From b0fb449b2268bc1e57fd99e00f3049175abd2126 Mon Sep 17 00:00:00 2001
From: Michael Ernst <mernst@cs.washington.edu>
Date: Wed, 20 Oct 2021 09:11:26 -0700
Subject: [PATCH 01/21] Improve JDK compatibility

---
 README-typetools.md      | 3 +++
 guava/cfMavenCentral.xml | 8 --------
 guava/pom.xml            | 6 +++---
 3 files changed, 6 insertions(+), 11 deletions(-)

diff --git a/README-typetools.md b/README-typetools.md
index 5c191148d14c..d0e748e7ea9e 100644
--- a/README-typetools.md
+++ b/README-typetools.md
@@ -68,6 +68,9 @@ Whenever a Checker Framework release is made:
 To update to a newer version of the upstream library
 ----------------------------------------------------
 
+First, update to use the latest Checker Framework by editing file
+`guava/pom.xml`.  Ensure that type-checking succeeds.
+
 Check for a release at
   https://github.com/google/guava/releases
 .  If there has been one since the last time this repository was pulled,
diff --git a/guava/cfMavenCentral.xml b/guava/cfMavenCentral.xml
index 117e82d48d2f..07bf025a9ca0 100644
--- a/guava/cfMavenCentral.xml
+++ b/guava/cfMavenCentral.xml
@@ -37,14 +37,6 @@
             <organizationUrl>https://www.cs.washington.edu/</organizationUrl>
         </developer>
 
-        <developer>
-            <id>wmdietl</id>
-            <name>Werner M. Dietl</name>
-            <email>wdietl@uwaterloo.ca</email>
-            <organization>University of Waterloo</organization>
-            <organizationUrl>http://uwaterloo.ca/</organizationUrl>
-        </developer>
-
         <developer>
             <id>Suzanne Millstein</id>
             <name>Suzanne Millstein</name>
diff --git a/guava/pom.xml b/guava/pom.xml
index f024d9ff58bd..0ab7ddb4c63d 100644
--- a/guava/pom.xml
+++ b/guava/pom.xml
@@ -74,7 +74,7 @@
     <dependency>
       <groupId>org.checkerframework</groupId>
       <artifactId>checker</artifactId>
-      <version>3.12.0</version>
+      <version>3.13.0</version>
     </dependency>
   </dependencies>
   <build>
@@ -376,9 +376,9 @@
       </build>
     </profile>
     <profile>
-      <id>jdk16</id>
+      <id>jdk17</id>
       <activation>
-        <jdk>16</jdk>
+        <jdk>[16,)</jdk>
       </activation>
       <build>
         <plugins>

From 615207f31f833c284880be0a7ee363da9aaba311 Mon Sep 17 00:00:00 2001
From: Michael Ernst <mernst@cs.washington.edu>
Date: Thu, 2 Dec 2021 16:36:56 -0800
Subject: [PATCH 02/21] Use Checker Framework version 3.19.0

---
 README-typetools.md | 3 ++-
 guava/pom.xml       | 2 +-
 pom.xml             | 2 +-
 3 files changed, 4 insertions(+), 3 deletions(-)

diff --git a/README-typetools.md b/README-typetools.md
index d0e748e7ea9e..4a2e614e9114 100644
--- a/README-typetools.md
+++ b/README-typetools.md
@@ -69,7 +69,8 @@ To update to a newer version of the upstream library
 ----------------------------------------------------
 
 First, update to use the latest Checker Framework by editing file
-`guava/pom.xml`.  Ensure that type-checking succeeds.
+`pom.xml` (for `checker-qual`) and `guava/pom.xml` (for `checker`).
+Make a pull request to ensure that type-checking succeeds.
 
 Check for a release at
   https://github.com/google/guava/releases
diff --git a/guava/pom.xml b/guava/pom.xml
index 0ab7ddb4c63d..ab65fb2e9a79 100644
--- a/guava/pom.xml
+++ b/guava/pom.xml
@@ -74,7 +74,7 @@
     <dependency>
       <groupId>org.checkerframework</groupId>
       <artifactId>checker</artifactId>
-      <version>3.13.0</version>
+      <version>3.19.0</version>
     </dependency>
   </dependencies>
   <build>
diff --git a/pom.xml b/pom.xml
index 74ebce71142b..eb05a1aa331f 100644
--- a/pom.xml
+++ b/pom.xml
@@ -274,7 +274,7 @@
       <dependency>
         <groupId>org.checkerframework</groupId>
         <artifactId>checker-qual</artifactId>
-        <version>3.12.0</version>
+        <version>3.19.0</version>
       </dependency>
       <dependency>
         <groupId>com.google.errorprone</groupId>

From b419ba82f9ad69a431723c73bb5912236767e494 Mon Sep 17 00:00:00 2001
From: Michael Ernst <mernst@cs.washington.edu>
Date: Tue, 31 Jan 2023 11:17:47 -0800
Subject: [PATCH 03/21] Expand note

---
 README-typetools.md | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/README-typetools.md b/README-typetools.md
index 4a2e614e9114..f552fdfd2b47 100644
--- a/README-typetools.md
+++ b/README-typetools.md
@@ -84,8 +84,9 @@ git pull https://github.com/google/guava
 ```
 
 and then re-build to ensure that typechecking still works.
-Doing this `git pull` permits incremental resolution of merge conflicts,
-but makes it difficult to re-release a given version of Guava.
+Note: Doing this `git pull` command
+makes it difficult to re-release a given version of Guava,
+compared to pulling in the tag corresponding to a release.
 
 If you wish to see a simplified diff between this fork of Guava and upstream (to make sure that you did not make any mistakes when resolving merge conflicts):
 

From 407e13feb22148907bbf1cc252a295578767ec75 Mon Sep 17 00:00:00 2001
From: Mark Roberts <markro@cs.washington.edu>
Date: Tue, 14 Feb 2023 10:53:17 -0800
Subject: [PATCH 04/21] update checker framework; clean up some suppressions

---
 guava/pom.xml                                 | 28 +++++++--
 .../com/google/common/base/CharMatcher.java   | 43 +------------
 .../google/common/base/SmallCharMatcher.java  |  2 +-
 guava/src/com/google/common/base/Strings.java | 15 -----
 .../com/google/common/cache/LongAdder.java    | 22 ++++---
 .../common/collect/CollectSpliterators.java   |  2 +-
 .../google/common/collect/CompactHashMap.java | 16 ++---
 .../google/common/collect/CompactHashSet.java | 14 +++--
 .../google/common/collect/ImmutableSet.java   |  1 +
 .../com/google/common/collect/Multiset.java   | 11 ++--
 .../src/com/google/common/collect/Table.java  | 18 +++---
 .../escape/ArrayBasedUnicodeEscaper.java      |  3 -
 .../google/common/escape/UnicodeEscaper.java  | 19 ------
 .../graph/DirectedGraphConnections.java       |  2 +-
 .../com/google/common/graph/Traverser.java    |  3 +-
 .../google/common/hash/AbstractHasher.java    |  9 +--
 .../AbstractNonStreamingHashFunction.java     | 10 +--
 .../common/hash/FarmHashFingerprint64.java    | 18 +-----
 guava/src/com/google/common/hash/Funnels.java | 13 ++--
 .../src/com/google/common/hash/HashCode.java  |  8 +--
 guava/src/com/google/common/hash/Hashing.java |  7 ++-
 .../src/com/google/common/hash/LongAdder.java | 23 ++++---
 .../hash/MessageDigestHashFunction.java       |  2 +-
 .../com/google/common/hash/PrimitiveSink.java |  2 +-
 .../com/google/common/io/BaseEncoding.java    | 29 +--------
 .../src/com/google/common/io/ByteSource.java  |  8 +--
 .../src/com/google/common/io/ByteStreams.java | 18 ++----
 .../common/io/FileBackedOutputStream.java     |  3 +-
 .../src/com/google/common/math/LongMath.java  | 62 +++++++------------
 .../src/com/google/common/math/Quantiles.java | 41 ++----------
 .../com/google/common/primitives/Ints.java    | 13 +---
 .../com/google/common/primitives/Longs.java   | 29 +++------
 .../common/primitives/UnsignedInteger.java    |  7 ++-
 .../common/primitives/UnsignedLong.java       | 34 +++++++---
 .../common/primitives/UnsignedLongs.java      | 16 ++++-
 .../common/util/concurrent/AtomicDouble.java  | 22 ++++---
 .../common/util/concurrent/ClosingFuture.java |  3 +-
 pom.xml                                       |  2 +-
 38 files changed, 224 insertions(+), 354 deletions(-)

diff --git a/guava/pom.xml b/guava/pom.xml
index ab65fb2e9a79..d0643e25e487 100644
--- a/guava/pom.xml
+++ b/guava/pom.xml
@@ -19,18 +19,33 @@
     <!-- Use -Dcheckerframework.checkers=checker to switch which checkers are run. -->
     <!-- Running the Index Checker takes very long but is needed to put implicit annotations in class files. -->
     <checkerframework.checkers>org.checkerframework.checker.index.IndexChecker,org.checkerframework.checker.nullness.NullnessChecker,org.checkerframework.checker.signedness.SignednessChecker</checkerframework.checkers>
+
     <!-- Index checker warnings are disabled by default, because not all code is annotated by index checker annotations. -->
     <checkerframework.suppress>index</checkerframework.suppress>
+
     <!-- Packages under com.google.common, that will be additionally checked by the Index Checker -->
     <checkerframework.index.packages>base|primitives|escape|math|io|hash</checkerframework.index.packages>
-    <!-- Additional argument passed to the java compiler. Use to pass additional arguments to the checker framework. Example: -Ashowchecks -->
+
+    <!-- Additional argument passed to the java compiler. Use to pass additional arguments
+         to the checker framework. Example: -Ashowchecks -->
     <checkerframework.extraargs></checkerframework.extraargs>
-    <!-- Additional argument passed to the java compiler. Use to pass additional arguments to the checker framework. Example: -Aannotations -->
+
+    <!-- Additional argument passed to the java compiler. Use to pass additional arguments
+         to the checker framework. Example: -Aannotations -->
     <checkerframework.extraargs2></checkerframework.extraargs2>
+
     <!-- The phase when the Index Checker is run. -->
     <check.index.phase>process-sources</check.index.phase>
+
     <!-- Additional argument passed to the Index Checker. Example: -Ashowchecks -->
     <index.only.arg></index.only.arg>
+
+    <!-- Use -Dmain-compile.skip=true to only run the check-index execution -->
+    <main-compile.skip>false</main-compile.skip>
+
+    <!-- Use -Djavac.verbose=true to compile with the verbose option.
+         This is used when you want to see stub parser warnings. -->
+    <javac.verbose>false</javac.verbose>
   </properties>
   <dependencies>
     <dependency>
@@ -74,7 +89,7 @@
     <dependency>
       <groupId>org.checkerframework</groupId>
       <artifactId>checker</artifactId>
-      <version>3.19.0</version>
+      <version>3.30.0</version>
     </dependency>
   </dependencies>
   <build>
@@ -131,7 +146,8 @@
               <Xmaxwarns>10000</Xmaxwarns>
             </compilerArguments>
             <showWarnings>true</showWarnings>
-	    <verbose>true</verbose>d
+            <!-- Default is verbose off, so you won't see stub parser warnings. -->
+            <verbose>${javac.verbose}</verbose>
             <annotationProcessors>
               <annotationProcessor>${checkerframework.checkers}</annotationProcessor>
             </annotationProcessors>
@@ -139,9 +155,12 @@
               <arg>${additionalargs}</arg>
               <arg>${checkerframework.extraargs}</arg>
               <arg>${checkerframework.extraargs2}</arg>
+              <!-- Default is supress all index checker warnings! -->
               <arg>-AsuppressWarnings=${checkerframework.suppress}</arg>
               <arg>-AuseDefaultsForUncheckedCode=source,bytecode</arg>
               <arg>-Awarns</arg>
+              <arg>-AshowSuppressWarningsStrings</arg>
+              <arg>-AwarnUnneededSuppressions</arg>
             </compilerArgs>
         </configuration>
         <executions>
@@ -194,6 +213,7 @@
               <goal>compile</goal>
             </goals>
             <configuration>
+              <skipMain>${main-compile.skip}</skipMain>
               <excludes>
                 <exclude>**/Java8Usage.java</exclude>
               </excludes>
diff --git a/guava/src/com/google/common/base/CharMatcher.java b/guava/src/com/google/common/base/CharMatcher.java
index 842a642e0fd4..f1d509c29262 100644
--- a/guava/src/com/google/common/base/CharMatcher.java
+++ b/guava/src/com/google/common/base/CharMatcher.java
@@ -319,7 +319,6 @@ public static CharMatcher isNot(final char match) {
    * The CharSequence is not mutated, therefore after checking its length,
    * accesses to lower indices are safe.
    */
-  @SuppressWarnings("upperbound:argument.type.incompatible") // https://github.com/kelloggm/checker-framework/issues/188
   public static CharMatcher anyOf(final CharSequence sequence) {
     switch (sequence.length()) {
       case 0:
@@ -453,7 +452,7 @@ public String toString() {
   /**
    * Helper method for {@link #precomputedInternal} that doesn't test if the negation is cheaper.
    */
-  @SuppressWarnings("index")  // table has bits if totalCharacters is sufficiently large
+  @SuppressWarnings("signedness:cast.unsafe")  // distance between true bits will fit in char
   @GwtIncompatible // SmallCharMatcher
   private static CharMatcher precomputedPositive(
       int totalCharacters, BitSet table, String description) {
@@ -608,7 +607,6 @@ public boolean matchesNoneOf(CharSequence sequence) {
   /*
    * count is incremented at most sequence.length() times
    */
-  @SuppressWarnings("unary.increment.type.incompatible") // variable incremented at most IndexOrHigh times
   public @IndexOrHigh("#1") int countIn(CharSequence sequence) {
     @IndexOrHigh("#1") int count = 0;
     for (int i = 0; i < sequence.length(); i++) {
@@ -629,20 +627,6 @@ public boolean matchesNoneOf(CharSequence sequence) {
    *
    * ... returns {@code "bzr"}.
    */
-  @SuppressWarnings({
-    /*
-     * at entry to OUT, pos is IndexFor("string"),
-     * and after each pos++, it is checked against chars.length
-     * if equal, pos is not incremented anymore
-     * therefore both pos++ are safe
-     */
-    "upperbound:unary.increment.type.incompatible", // index incremented in nested loop with break
-    "upperbound:array.access.unsafe.high", "upperbound:argument.type.incompatible", // https://github.com/kelloggm/checker-framework/issues/204
-    /*
-     * spread <= pos, therefore pos-spread >= 0
-     */
-    "lowerbound:array.access.unsafe.low", "lowerbound:argument.type.incompatible" // https://github.com/kelloggm/checker-framework/issues/158
-  })
   public String removeFrom(CharSequence sequence) {
     String string = sequence.toString();
     @GTENegativeOne @LTEqLengthOf("string") int pos = indexIn(string);
@@ -744,9 +728,6 @@ public String replaceFrom(CharSequence sequence, char replacement) {
    * replacementLen should be @IndexOrHigh("replacement")
    * indexIn should return @IndexOrLow("#1")
    */
-  @SuppressWarnings({
-    "upperbound:argument.type.incompatible", // https://github.com/kelloggm/checker-framework/issues/188
-  })
   public String replaceFrom(CharSequence sequence, CharSequence replacement) {
     int replacementLen = replacement.length();
     if (replacementLen == 0) {
@@ -879,7 +860,6 @@ public String trimTrailingFrom(CharSequence sequence) {
    * i should be @IndexOrHigh("sequence")
    * inside the loop, i is @IndexFor("sequence")
    */
-  @SuppressWarnings("upperbound:argument.type.incompatible") // refinement by inequality with expression referring to length in a local variable
   public String collapseFrom(CharSequence sequence, char replacement) {
     // This implementation avoids unnecessary allocation.
     int len = sequence.length();
@@ -909,9 +889,6 @@ public String collapseFrom(CharSequence sequence, char replacement) {
    * last should be @IndexFor("sequence")
    * last >= first
    */
-  @SuppressWarnings({
-    "lowerbound:argument.type.incompatible", // https://github.com/kelloggm/checker-framework/issues/158
-  })
   public String trimAndCollapseFrom(CharSequence sequence, char replacement) {
     // This implementation avoids unnecessary allocation.
     int len = sequence.length();
@@ -977,7 +954,6 @@ public String toString() {
    * Returns the Java Unicode escape sequence for the given {@code char}, in the form "\u12AB" where
    * "12AB" is the four hexadecimal digits representing the 16-bit code unit.
    */
-  @SuppressWarnings("index") // https://github.com/typetools/checker-framework/issues/2540
   private static String showCharacter(char c) {
     String hex = "0123456789ABCDEF";
     char[] tmp = {'\\', 'u', '\0', '\0', '\0', '\0'};
@@ -1048,7 +1024,6 @@ private BitSetMatcher(BitSet table, String description) {
     }
 
     @Override
-    @SuppressWarnings("lowerbound:argument.type.incompatible") // https://github.com/kelloggm/checker-framework/issues/192 char should be @NonNegative
     public boolean matches(char c) {
       return table.get(c);
     }
@@ -1078,7 +1053,6 @@ public boolean matches(char c) {
     /*
      * If length() != 0, then sequence is MinLen(1), so 0 is LTLengthOf(sequence)
      */
-    @SuppressWarnings("upperbound:return.type.incompatible") // https://github.com/kelloggm/checker-framework/issues/188
     @Override
     public @IndexOrLow("#1") int indexIn(CharSequence sequence) {
       return (sequence.length() == 0) ? -1 : 0;
@@ -1087,7 +1061,6 @@ public boolean matches(char c) {
     /*
      * If start != length(), then start is LTLengthOf(sequence)
      */
-    @SuppressWarnings("upperbound:return.type.incompatible") // Refine index by comparison to length method
     @Override
     public @IndexOrLow("#1") int indexIn(CharSequence sequence, @IndexOrHigh("#1") int start) {
       int length = sequence.length();
@@ -1292,14 +1265,12 @@ static final class Whitespace extends NamedFastMatcher {
     }
 
     @Override
-    @SuppressWarnings("index:argument.type.incompatible") // unsigned right shift on int
     public boolean matches(char c) {
       return TABLE.charAt((MULTIPLIER * c) >>> SHIFT) == c;
     }
 
     @GwtIncompatible // used only from other GwtIncompatible code
     @Override
-    @SuppressWarnings("lowerbound:argument.type.incompatible") // https://github.com/kelloggm/checker-framework/issues/192 char should be @NonNegative
     void setBits(BitSet table) {
       for (int i = 0; i < TABLE.length(); i++) {
         table.set(TABLE.charAt(i));
@@ -1410,7 +1381,6 @@ private static final class Digit extends RangesMatcher {
       return ZEROES.toCharArray();
     }
 
-    @SuppressWarnings("index") // https://github.com/typetools/checker-framework/issues/2540
     private static char @SameLen("ZEROES")[] nines() {
       char[] nines = new char[ZEROES.length()];
       for (int i = 0; i < ZEROES.length(); i++) {
@@ -1421,7 +1391,6 @@ private static final class Digit extends RangesMatcher {
 
     static final Digit INSTANCE = new Digit();
 
-    @SuppressWarnings("samelen:argument.type.incompatible") // SameLen on method calls
     private Digit() {
       super("CharMatcher.digit()", zeroes(), nines());
     }
@@ -1537,7 +1506,6 @@ private static final class Invisible extends RangesMatcher {
 
     static final Invisible INSTANCE = new Invisible();
 
-    @SuppressWarnings("samelen:argument.type.incompatible") // https://github.com/kelloggm/checker-framework/issues/179
     private Invisible() {
       super("CharMatcher.invisible()", RANGE_STARTS.toCharArray(), RANGE_ENDS.toCharArray());
     }
@@ -1548,7 +1516,6 @@ private static final class SingleWidth extends RangesMatcher {
 
     static final SingleWidth INSTANCE = new SingleWidth();
 
-    @SuppressWarnings("samelen:argument.type.incompatible") // https://github.com/kelloggm/checker-framework/issues/179
     private SingleWidth() {
       super(
           "CharMatcher.singleWidth()",
@@ -1584,7 +1551,6 @@ public boolean matchesNoneOf(CharSequence sequence) {
     }
 
     @Override
-    @SuppressWarnings("lowerbound:return.type.incompatible") // https://github.com/kelloggm/checker-framework/issues/193
     public @IndexOrHigh("#1") int countIn(CharSequence sequence) {
       return sequence.length() - original.countIn(sequence);
     }
@@ -1709,7 +1675,6 @@ public CharMatcher negate() {
 
     @GwtIncompatible // used only from other GwtIncompatible code
     @Override
-    @SuppressWarnings("lowerbound:argument.type.incompatible") // https://github.com/kelloggm/checker-framework/issues/192 char should be @NonNegative
     void setBits(BitSet table) {
       table.set(match);
     }
@@ -1746,7 +1711,6 @@ public CharMatcher or(CharMatcher other) {
 
     @GwtIncompatible // used only from other GwtIncompatible code
     @Override
-    @SuppressWarnings("lowerbound:argument.type.incompatible") // https://github.com/kelloggm/checker-framework/issues/192 char should be @NonNegative
     void setBits(BitSet table) {
       table.set(0, match);
       table.set(match + 1, Character.MAX_VALUE + 1);
@@ -1785,7 +1749,6 @@ public boolean matches(char c) {
 
     @GwtIncompatible // used only from other GwtIncompatible code
     @Override
-    @SuppressWarnings("lowerbound:argument.type.incompatible") // https://github.com/kelloggm/checker-framework/issues/192 char should be @NonNegative
     void setBits(BitSet table) {
       table.set(match1);
       table.set(match2);
@@ -1814,7 +1777,6 @@ public boolean matches(char c) {
 
     @Override
     @GwtIncompatible // used only from other GwtIncompatible code
-    @SuppressWarnings("lowerbound:argument.type.incompatible") // https://github.com/kelloggm/checker-framework/issues/192 char should be @NonNegative
     void setBits(BitSet table) {
       for (char c : chars) {
         table.set(c);
@@ -1851,7 +1813,6 @@ public boolean matches(char c) {
 
     @GwtIncompatible // used only from other GwtIncompatible code
     @Override
-    @SuppressWarnings("lowerbound:argument.type.incompatible") // https://github.com/kelloggm/checker-framework/issues/192 char should be @NonNegative
     void setBits(BitSet table) {
       table.set(startInclusive, endInclusive + 1);
     }
@@ -1880,8 +1841,8 @@ public boolean matches(char c) {
       return predicate.apply(c);
     }
 
-    @SuppressWarnings("deprecation") // intentional; deprecation is for callers primarily
     @Override
+    @SuppressWarnings("signedness:type.argument")
     public boolean apply(Character character) {
       return predicate.apply(checkNotNull(character));
     }
diff --git a/guava/src/com/google/common/base/SmallCharMatcher.java b/guava/src/com/google/common/base/SmallCharMatcher.java
index b57eef48d016..c0842c911b9f 100644
--- a/guava/src/com/google/common/base/SmallCharMatcher.java
+++ b/guava/src/com/google/common/base/SmallCharMatcher.java
@@ -90,7 +90,7 @@ private boolean checkFilter(int c) {
   /*
    * chars should be at most 65536 bits and not all zeroes
    */
-  @SuppressWarnings("value:argument.type.incompatible") // https://github.com/kelloggm/checker-framework/issues/197
+  @SuppressWarnings("value:argument") // size is in range as arg to chooseTableSize
   static CharMatcher from(BitSet chars, String description) {
     // Compute the filter.
     long filter = 0;
diff --git a/guava/src/com/google/common/base/Strings.java b/guava/src/com/google/common/base/Strings.java
index 67ef68200300..8d86b71cb1ef 100644
--- a/guava/src/com/google/common/base/Strings.java
+++ b/guava/src/com/google/common/base/Strings.java
@@ -145,16 +145,6 @@ public static String padEnd(String string, int minLength, char padChar) {
    *     {@code count} is zero)
    * @throws IllegalArgumentException if {@code count} is negative
    */
-  @SuppressWarnings({
-    "upperbound:argument.type.incompatible", "upperbound:assignment.type.incompatible", // https://github.com/kelloggm/checker-framework/issues/158
-    /*
-     * After checking that n < size - n, we know that 2*n < size,
-     * therefore n << 1 < size,
-     * therefore n <<= 1 does not break IndexOrHigh("array").
-     */
-    "upperbound:compound.assignment.type.incompatible", // multiply index by 2 using bit shift
-    "lowerbound:argument.type.incompatible", // https://github.com/kelloggm/checker-framework/issues/193
-  })
   public static String repeat(String string, @NonNegative int count) {
     checkNotNull(string); // eager for GWT.
 
@@ -188,7 +178,6 @@ public static String repeat(String string, @NonNegative int count) {
    *
    * @since 11.0
    */
-  @SuppressWarnings("index:unary.decrement.type.incompatible") // i-1 is @NonNegative means i-- is @NonNegative
   public static String commonPrefix(CharSequence a, CharSequence b) {
     checkNotNull(a);
     checkNotNull(b);
@@ -212,10 +201,6 @@ public static String commonPrefix(CharSequence a, CharSequence b) {
    *
    * @since 11.0
    */
-  @SuppressWarnings({
-    "lowerbound:argument.type.incompatible", // https://github.com/kelloggm/checker-framework/issues/193
-    "lowerbound:unary.decrement.type.incompatible" // i-1 is @NonNegative means i-- is @NonNegative
-  })
   public static String commonSuffix(CharSequence a, CharSequence b) {
     checkNotNull(a);
     checkNotNull(b);
diff --git a/guava/src/com/google/common/cache/LongAdder.java b/guava/src/com/google/common/cache/LongAdder.java
index f0c44ffbc697..9b09b63749e8 100644
--- a/guava/src/com/google/common/cache/LongAdder.java
+++ b/guava/src/com/google/common/cache/LongAdder.java
@@ -18,6 +18,8 @@
 import java.io.Serializable;
 import java.util.concurrent.atomic.AtomicLong;
 
+import org.checkerframework.common.value.qual.PolyValue;
+
 /**
  * One or more variables that together maintain an initially zero {@code long} sum. When updates
  * (method {@link #add}) are contended across threads, the set of variables may grow dynamically to
@@ -157,26 +159,30 @@ public String toString() {
    * @return the sum
    */
   @Override
-  public long longValue() {
-    return sum();
+  @SuppressWarnings("cast.unsafe")
+  public @PolyValue long longValue(@PolyValue LongAdder this) {
+    return (@PolyValue long) sum();
   }
 
   /** Returns the {@link #sum} as an {@code int} after a narrowing primitive conversion. */
   @Override
-  public int intValue() {
-    return (int) sum();
+  @SuppressWarnings("cast.unsafe")
+  public @PolyValue int intValue(@PolyValue LongAdder this) {
+    return (@PolyValue int) sum();
   }
 
   /** Returns the {@link #sum} as a {@code float} after a widening primitive conversion. */
   @Override
-  public float floatValue() {
-    return (float) sum();
+  @SuppressWarnings("cast.unsafe")
+  public @PolyValue float floatValue(@PolyValue LongAdder this) {
+    return (@PolyValue float) sum();
   }
 
   /** Returns the {@link #sum} as a {@code double} after a widening primitive conversion. */
   @Override
-  public double doubleValue() {
-    return (double) sum();
+  @SuppressWarnings("cast.unsafe")
+  public @PolyValue double doubleValue(@PolyValue LongAdder this) {
+    return (@PolyValue double) sum();
   }
 
   private void writeObject(ObjectOutputStream s) throws IOException {
diff --git a/guava/src/com/google/common/collect/CollectSpliterators.java b/guava/src/com/google/common/collect/CollectSpliterators.java
index 974f77fdc0ec..6bced4aa8e6e 100644
--- a/guava/src/com/google/common/collect/CollectSpliterators.java
+++ b/guava/src/com/google/common/collect/CollectSpliterators.java
@@ -302,7 +302,7 @@ OutSpliteratorT newFlatMapSpliterator(
           long estSplitSize);
     }
 
-    @Nullable @Weak OutSpliteratorT prefix;
+    @Weak @Nullable OutSpliteratorT prefix;
     final Spliterator<InElementT> from;
     final Function<? super InElementT, OutSpliteratorT> function;
     final Factory<InElementT, OutSpliteratorT> factory;
diff --git a/guava/src/com/google/common/collect/CompactHashMap.java b/guava/src/com/google/common/collect/CompactHashMap.java
index a68890e82b03..e44153aabfec 100644
--- a/guava/src/com/google/common/collect/CompactHashMap.java
+++ b/guava/src/com/google/common/collect/CompactHashMap.java
@@ -48,6 +48,9 @@
 import java.util.function.BiFunction;
 import java.util.function.Consumer;
 import org.checkerframework.checker.nullness.qual.Nullable;
+import org.checkerframework.checker.nullness.qual.PolyNull;
+import org.checkerframework.checker.signedness.qual.PolySigned;
+import org.checkerframework.checker.signedness.qual.UnknownSignedness;
 
 /**
  * CompactHashMap is an implementation of a Map. All optional operations (put and remove) are
@@ -138,7 +141,7 @@ public static <K, V> CompactHashMap<K, V> createWithExpectedSize(int expectedSiz
    *   <li>null, if no entries have yet been added to the map
    * </ul>
    */
-  @Nullable private transient Object table;
+  private transient @Nullable Object table;
 
   /**
    * Contains the logical entries, in the range of [0, size()). The high bits of each int are the
@@ -439,14 +442,14 @@ private int indexOf(@Nullable Object key) {
   }
 
   @Override
-  public boolean containsKey(@Nullable Object key) {
+  public boolean containsKey(@Nullable @UnknownSignedness Object key) {
     @Nullable Map<K, V> delegate = delegateOrNull();
     return (delegate != null) ? delegate.containsKey(key) : indexOf(key) != -1;
   }
 
   @SuppressWarnings("unchecked") // known to be a V
   @Override
-  public V get(@Nullable Object key) {
+  public V get(@Nullable @UnknownSignedness Object key) {
     @Nullable Map<K, V> delegate = delegateOrNull();
     if (delegate != null) {
       return delegate.get(key);
@@ -462,7 +465,7 @@ public V get(@Nullable Object key) {
   @CanIgnoreReturnValue
   @SuppressWarnings("unchecked") // known to be a V
   @Override
-  public @Nullable V remove(@Nullable Object key) {
+  public @Nullable V remove(@Nullable @UnknownSignedness Object key) {
     @Nullable Map<K, V> delegate = delegateOrNull();
     if (delegate != null) {
       return delegate.remove(key);
@@ -629,7 +632,7 @@ class KeySetView extends Maps.KeySet<K, V> {
     }
 
     @Override
-    public Object[] toArray() {
+    public @PolySigned Object[] toArray(CompactHashMap<@PolySigned K, @PolySigned V>.KeySetView this) {
       if (needsAllocArrays()) {
         return new Object[0];
       }
@@ -817,9 +820,8 @@ final class MapEntry extends AbstractMapEntry<K, V> {
       this.lastKnownIndex = index;
     }
 
-    @Nullable
     @Override
-    public K getKey() {
+    public @Nullable K getKey() {
       return key;
     }
 
diff --git a/guava/src/com/google/common/collect/CompactHashSet.java b/guava/src/com/google/common/collect/CompactHashSet.java
index d54e16648143..d344da6597c4 100644
--- a/guava/src/com/google/common/collect/CompactHashSet.java
+++ b/guava/src/com/google/common/collect/CompactHashSet.java
@@ -45,6 +45,8 @@
 import java.util.Spliterators;
 import java.util.function.Consumer;
 import org.checkerframework.checker.nullness.qual.Nullable;
+import org.checkerframework.checker.signedness.qual.PolySigned;
+import org.checkerframework.checker.signedness.qual.UnknownSignedness;
 
 /**
  * CompactHashSet is an implementation of a Set. All optional operations (adding and removing) are
@@ -155,7 +157,7 @@ public static <E> CompactHashSet<E> createWithExpectedSize(int expectedSize) {
    *   <li>null, if no entries have yet been added to the map
    * </ul>
    */
-  @Nullable private transient Object table;
+  private transient @Nullable Object table;
 
   /**
    * Contains the logical entries, in the range of [0, size()). The high bits of each int are the
@@ -300,6 +302,7 @@ public boolean add(@Nullable E object) {
 
     int newEntryIndex = this.size; // current size, and pointer to the entry to be appended
     int newSize = newEntryIndex + 1;
+    @SuppressWarnings("signedness:argument")
     int hash = smearedHash(object);
     int mask = hashTableMask();
     int tableIndex = hash & mask;
@@ -348,6 +351,7 @@ public boolean add(@Nullable E object) {
   /**
    * Creates a fresh entry with the specified object at the specified position in the entry arrays.
    */
+  @SuppressWarnings("signedness:assignment")
   void insertEntry(int entryIndex, @Nullable E object, int hash, int mask) {
     this.entries[entryIndex] = CompactHashing.maskCombine(hash, UNSET, mask);
     this.elements[entryIndex] = object;
@@ -413,7 +417,7 @@ private int resizeTable(int mask, int newCapacity, int targetHash, int targetEnt
   }
 
   @Override
-  public boolean contains(@Nullable Object object) {
+  public boolean contains(@Nullable @UnknownSignedness Object object) {
     if (needsAllocArrays()) {
       return false;
     }
@@ -442,7 +446,7 @@ public boolean contains(@Nullable Object object) {
 
   @CanIgnoreReturnValue
   @Override
-  public boolean remove(@Nullable Object object) {
+  public boolean remove(@Nullable @UnknownSignedness Object object) {
     if (needsAllocArrays()) {
       return false;
     }
@@ -610,7 +614,7 @@ public boolean isEmpty() {
   }
 
   @Override
-  public Object[] toArray() {
+  public @PolySigned Object[] toArray(CompactHashSet<@PolySigned E> this) {
     if (needsAllocArrays()) {
       return new Object[0];
     }
@@ -660,6 +664,7 @@ public void trimToSize() {
   }
 
   @Override
+  @SuppressWarnings("signedness:argument")
   public void clear() {
     if (needsAllocArrays()) {
       return;
@@ -680,6 +685,7 @@ public void clear() {
     }
   }
 
+  @SuppressWarnings("signedness:argument")
   private void writeObject(ObjectOutputStream stream) throws IOException {
     stream.defaultWriteObject();
     stream.writeInt(size());
diff --git a/guava/src/com/google/common/collect/ImmutableSet.java b/guava/src/com/google/common/collect/ImmutableSet.java
index f2a8724897bb..9ee2d958c184 100644
--- a/guava/src/com/google/common/collect/ImmutableSet.java
+++ b/guava/src/com/google/common/collect/ImmutableSet.java
@@ -639,6 +639,7 @@ SetBuilderImpl<E> review() {
   private static final double DESIRED_LOAD_FACTOR = 0.7;
 
   // If the set has this many elements, it will "max out" the table size
+  @SuppressWarnings("cast.unsafe") // cast float to int
   private static final int CUTOFF = (int) (MAX_TABLE_SIZE * DESIRED_LOAD_FACTOR);
 
   /**
diff --git a/guava/src/com/google/common/collect/Multiset.java b/guava/src/com/google/common/collect/Multiset.java
index 24e7b19f21da..b7fa165778ba 100644
--- a/guava/src/com/google/common/collect/Multiset.java
+++ b/guava/src/com/google/common/collect/Multiset.java
@@ -31,6 +31,7 @@
 import java.util.function.Consumer;
 import java.util.function.ObjIntConsumer;
 import org.checkerframework.checker.nullness.qual.Nullable;
+import org.checkerframework.checker.signedness.qual.UnknownSignedness;
 import org.checkerframework.dataflow.qual.Pure;
 import org.checkerframework.dataflow.qual.SideEffectFree;
 import org.checkerframework.framework.qual.AnnotatedFor;
@@ -111,7 +112,7 @@ public interface Multiset<E> extends Collection<E> {
    * @return the number of occurrences of the element in this multiset; possibly zero but never
    *     negative
    */
-  int count(@Nullable @CompatibleWith("E") Object element);
+  int count(@CompatibleWith("E") @Nullable Object element);
 
   // Bulk Operations
 
@@ -172,7 +173,7 @@ public interface Multiset<E> extends Collection<E> {
    * @throws IllegalArgumentException if {@code occurrences} is negative
    */
   @CanIgnoreReturnValue
-  int remove(@Nullable @CompatibleWith("E") Object element, int occurrences);
+  int remove(@CompatibleWith("E") @Nullable Object element, int occurrences);
 
   /**
    * Removes a <i>single</i> occurrence of the specified element from this multiset, if present.
@@ -188,7 +189,7 @@ public interface Multiset<E> extends Collection<E> {
    */
   @CanIgnoreReturnValue
   @Override
-  boolean remove(@Nullable Object element);
+  boolean remove(@Nullable @UnknownSignedness Object element);
 
   /**
    * Adds or removes the necessary occurrences of an element such that the element attains the
@@ -356,7 +357,7 @@ default void forEachEntry(ObjIntConsumer<? super E> action) {
   @Pure
   @Override
   // TODO(kevinb): caveats about equivalence-relation?
-  boolean equals(@Nullable Object object);
+  boolean equals(@Nullable @UnknownSignedness Object object);
 
   /**
    * Returns the hash code for this multiset. This is defined as the sum of
@@ -405,7 +406,7 @@ default void forEachEntry(ObjIntConsumer<? super E> action) {
    */
   @Pure
   @Override
-  boolean contains(@Nullable Object element);
+  boolean contains(@Nullable @UnknownSignedness Object element);
 
   /**
    * Returns {@code true} if this multiset contains at least one occurrence of each element in the
diff --git a/guava/src/com/google/common/collect/Table.java b/guava/src/com/google/common/collect/Table.java
index 136ec1742521..bb9448adc7ec 100644
--- a/guava/src/com/google/common/collect/Table.java
+++ b/guava/src/com/google/common/collect/Table.java
@@ -67,29 +67,29 @@ public interface Table<R, C, V> {
    * @param columnKey key of column to search for
    */
   boolean contains(
-      @Nullable @CompatibleWith("R") Object rowKey,
-      @Nullable @CompatibleWith("C") Object columnKey);
+      @CompatibleWith("R") @Nullable Object rowKey,
+      @CompatibleWith("C") @Nullable Object columnKey);
 
   /**
    * Returns {@code true} if the table contains a mapping with the specified row key.
    *
    * @param rowKey key of row to search for
    */
-  boolean containsRow(@Nullable @CompatibleWith("R") Object rowKey);
+  boolean containsRow(@CompatibleWith("R") @Nullable Object rowKey);
 
   /**
    * Returns {@code true} if the table contains a mapping with the specified column.
    *
    * @param columnKey key of column to search for
    */
-  boolean containsColumn(@Nullable @CompatibleWith("C") Object columnKey);
+  boolean containsColumn(@CompatibleWith("C") @Nullable Object columnKey);
 
   /**
    * Returns {@code true} if the table contains a mapping with the specified value.
    *
    * @param value value to search for
    */
-  boolean containsValue(@Nullable @CompatibleWith("V") Object value);
+  boolean containsValue(@CompatibleWith("V") @Nullable Object value);
 
   /**
    * Returns the value corresponding to the given row and column keys, or {@code null} if no such
@@ -100,8 +100,8 @@ boolean contains(
    */
   @Nullable
   V get(
-      @Nullable @CompatibleWith("R") Object rowKey,
-      @Nullable @CompatibleWith("C") Object columnKey);
+      @CompatibleWith("R") @Nullable Object rowKey,
+      @CompatibleWith("C") @Nullable Object columnKey);
 
   /** Returns {@code true} if the table contains no mappings. */
   boolean isEmpty();
@@ -160,8 +160,8 @@ V get(
   @CanIgnoreReturnValue
   @Nullable
   V remove(
-      @Nullable @CompatibleWith("R") Object rowKey,
-      @Nullable @CompatibleWith("C") Object columnKey);
+      @CompatibleWith("R") @Nullable Object rowKey,
+      @CompatibleWith("C") @Nullable Object columnKey);
 
   // Views
 
diff --git a/guava/src/com/google/common/escape/ArrayBasedUnicodeEscaper.java b/guava/src/com/google/common/escape/ArrayBasedUnicodeEscaper.java
index ce6a3ad27b56..d98ad0563ea7 100644
--- a/guava/src/com/google/common/escape/ArrayBasedUnicodeEscaper.java
+++ b/guava/src/com/google/common/escape/ArrayBasedUnicodeEscaper.java
@@ -96,7 +96,6 @@ protected ArrayBasedUnicodeEscaper(
    * @param unsafeReplacement the default replacement for unsafe characters or null if no default
    *     replacement is required
    */
-  @SuppressWarnings("index:assignment.type.incompatible") // implementation sets formal parameter
   protected ArrayBasedUnicodeEscaper(
       ArrayBasedEscaperMap escaperMap,
       @NonNegative int safeMin,
@@ -144,7 +143,6 @@ protected ArrayBasedUnicodeEscaper(
    * This is overridden to improve performance. Rough benchmarking shows that this almost doubles
    * the speed when processing strings that do not require any escaping.
    */
-  @SuppressWarnings("lowerbound:array.access.unsafe.low")//char types are non negative: https://github.com/kelloggm/checker-framework/issues/192
   @Override
   public final String escape(String s) {
     checkNotNull(s); // GWT specific check (do not optimize)
@@ -179,7 +177,6 @@ protected final char[] escape(@NonNegative int cp) {
   }
 
   /* Overridden for performance. */
-  @SuppressWarnings("lowerbound:array.access.unsafe.low")//char types are non negative: https://github.com/kelloggm/checker-framework/issues/192
   @Override
   protected final @IndexOrHigh("#1") int nextEscapeIndex(CharSequence csq, @IndexOrHigh("#1") int index, @IndexOrHigh("#1") int end) {
     while (index < end) {
diff --git a/guava/src/com/google/common/escape/UnicodeEscaper.java b/guava/src/com/google/common/escape/UnicodeEscaper.java
index 9cb8b7a2b0e8..ca956066627f 100644
--- a/guava/src/com/google/common/escape/UnicodeEscaper.java
+++ b/guava/src/com/google/common/escape/UnicodeEscaper.java
@@ -133,9 +133,6 @@ public String escape(String string) {
    * @throws IllegalArgumentException if the scanned sub-sequence of {@code csq} contains invalid
    *     surrogate pairs
    */
-  @SuppressWarnings("upperbound:compound.assignment.type.incompatible")/* (1) In char arrays and CharSequence and its subclasses, two chars are used to represent
-          unicode characters that are outside the range of a 16-bit char character. If cp is in the larger range then there is guaranteed to be another
-          character following the one located at index, which is the rest of the unicode character. */
   protected @IndexOrHigh("#1") int nextEscapeIndex(CharSequence csq, @IndexOrHigh("#1") int start, @IndexOrHigh("#1") int end) {
     @IndexOrHigh("#1") int index = start;
     while (index < end) {
@@ -163,18 +160,6 @@ public String escape(String string) {
    * @throws NullPointerException if {@code string} is null
    * @throws IllegalArgumentException if invalid surrogate characters are encountered
    */
-  @SuppressWarnings(value = {"upperbound:compound.assignment.type.incompatible",/*
-          (1): `destIndex` is always @LTEqLengthOf("dest") @LessThan("destSize + 1") because `dest` array
-          will always be regrow when `destSize` is less than `sizeNeeded` */
-          "upperbound:argument.type.incompatible",/*
-          (2): Because of System.arraycopy() method, `escaped.length` is required to be
-          @LTLengthOf(value={"escaped", "dest"}, offset={"-1", "destIndex - 1"}).
-          `escaped.length + destIndex - 1 < dest.length` is true because when `dest.length < sizeNeeded`,
-          `dest.length` regrow to new `destLength = destIndex + charsSkipped + escaped.length + (end - index) + DEST_PAD`
-          Since escaped.length is length of `escaped`, it should already be inferred to have length of @LTLengthOf(value="escaped", offset="-1") */
-          "upperbound:assignment.type.incompatible"/* (3): In char arrays and CharSequence and its subclasses, two chars are used to represent
-          unicode characters that are outside the range of a 16-bit char character. If cp is in the larger range then there is guaranteed to be another
-          character following the one located at index, which is the rest of the unicode character. */})
   protected final String escapeSlow(String s, @IndexOrHigh("#1") int index) {
     int end = s.length();
 
@@ -263,8 +248,6 @@ protected final String escapeSlow(String s, @IndexOrHigh("#1") int index) {
    * @return the Unicode code point for the given index or the negated value of the trailing high
    *     surrogate character at the end of the sequence
    */
-  @SuppressWarnings("upperbound:argument.type.incompatible")/* highest possible `end` value is `seq.length`,
-  `indexInternal` can't be >= seq.length in while loop.*/
   protected static int codePointAt(CharSequence seq, @IndexFor("#1") int index, @IndexOrHigh("#1") int end) {
     checkNotNull(seq);
     @IndexOrHigh("seq") int indexInternal = index;
@@ -313,8 +296,6 @@ protected static int codePointAt(CharSequence seq, @IndexFor("#1") int index, @I
    * Helper method to grow the character buffer as needed, this only happens once in a while so it's
    * ok if it's in a method call. If the index passed in is 0 then no copying will be done.
    */
-  @SuppressWarnings("upperbound:argument.type.incompatible")//upper bound checker does not infer size
-  //as size of the array. Issue: https://github.com/typetools/checker-framework/issues/2029
   private static char[] growBuffer(char[] dest,  @LTEqLengthOf("#1") @LessThan("#3 + 1") int index, int size) {
     if (size < 0) { // overflow - should be OutOfMemoryError but GWT/j2cl don't support it
       throw new AssertionError("Cannot increase internal buffer any further");
diff --git a/guava/src/com/google/common/graph/DirectedGraphConnections.java b/guava/src/com/google/common/graph/DirectedGraphConnections.java
index 3838bcfe8b74..ac5d08961a20 100644
--- a/guava/src/com/google/common/graph/DirectedGraphConnections.java
+++ b/guava/src/com/google/common/graph/DirectedGraphConnections.java
@@ -133,7 +133,7 @@ public int hashCode() {
    * LinkedHashMap combines two such edges into a single node-value pair, even though the edges may
    * not have been inserted consecutively.
    */
-  @Nullable private final List<NodeConnection<N>> orderedNodeConnections;
+  private final @Nullable List<NodeConnection<N>> orderedNodeConnections;
 
   private int predecessorCount;
   private int successorCount;
diff --git a/guava/src/com/google/common/graph/Traverser.java b/guava/src/com/google/common/graph/Traverser.java
index be0eecb5f6fd..b5e674950e5b 100644
--- a/guava/src/com/google/common/graph/Traverser.java
+++ b/guava/src/com/google/common/graph/Traverser.java
@@ -478,8 +478,7 @@ protected N computeNext() {
      * into {@code horizon} between calls to {@code visitNext()}. This causes them to receive
      * additional values interleaved with those shown above.)
      */
-    @Nullable
-    abstract N visitNext(Deque<Iterator<? extends N>> horizon);
+    abstract @Nullable N visitNext(Deque<Iterator<? extends N>> horizon);
   }
 
   /** Poor man's method reference for {@code Deque::addFirst} and {@code Deque::addLast}. */
diff --git a/guava/src/com/google/common/hash/AbstractHasher.java b/guava/src/com/google/common/hash/AbstractHasher.java
index 16e1b04ca948..8d658827c243 100644
--- a/guava/src/com/google/common/hash/AbstractHasher.java
+++ b/guava/src/com/google/common/hash/AbstractHasher.java
@@ -53,15 +53,12 @@ public Hasher putUnencodedChars(CharSequence charSequence) {
     return this;
   }
 
-  @SuppressWarnings("argument.type.incompatible")//Strings#getBytes() should be annotated as @PolyValue
   @Override
+  @SuppressWarnings("value:argument") // Strings#getBytes() should be annotated as @PolyValue
   public Hasher putString(@MinLen(1) CharSequence charSequence, Charset charset) {
     return putBytes(charSequence.toString().getBytes(charset));
   }
 
-  @SuppressWarnings("upperbound:argument.type.incompatible")/* `off` is required to be @LTLengthOf(value = "#1", offset = "len - 1"). Since `bytes.length` min value is 1,
-  `off = 0` + `bytes.length = 1" - 1 is still less than `bytes.length`
-  */
   @Override
   public Hasher putBytes(byte @MinLen(1)[] bytes) {
     return putBytes(bytes, 0, bytes.length);
@@ -77,8 +74,6 @@ public Hasher putBytes(byte[] bytes, @NonNegative @LTLengthOf(value = "#1", offs
   }
 
   @Override
-  @SuppressWarnings({"lowerbound:argument.type.incompatible" //  b.arrayOffset(), b.position() and b.remaining() all return non negative values.
-  })
   public Hasher putBytes(ByteBuffer b) {
     if (b.hasArray()) {
       putBytes(b.array(), b.arrayOffset() + b.position(), b.remaining());
@@ -108,6 +103,7 @@ public Hasher putInt(int i) {
   }
 
   @Override
+  @SuppressWarnings("signedness:shift.unsigned")
   public Hasher putLong(long l) {
     for (int i = 0; i < 64; i += 8) {
       putByte((byte) (l >>> i));
@@ -116,6 +112,7 @@ public Hasher putLong(long l) {
   }
 
   @Override
+  @SuppressWarnings("signedness:argument")
   public Hasher putChar(char c) {
     putByte((byte) c);
     putByte((byte) (c >>> 8));
diff --git a/guava/src/com/google/common/hash/AbstractNonStreamingHashFunction.java b/guava/src/com/google/common/hash/AbstractNonStreamingHashFunction.java
index 6d383622b89f..80af6d3ed278 100644
--- a/guava/src/com/google/common/hash/AbstractNonStreamingHashFunction.java
+++ b/guava/src/com/google/common/hash/AbstractNonStreamingHashFunction.java
@@ -46,7 +46,7 @@ public Hasher newHasher(@NonNegative int expectedInputSize) {
     return new BufferingHasher(expectedInputSize);
   }
 
-  @SuppressWarnings("value:argument.type.incompatible")/* Since ByteBuffer is a mutable length data structure, `ByteBuffer.allocate(4)`
+  @SuppressWarnings("value:argument") /* Since ByteBuffer is a mutable length data structure, `ByteBuffer.allocate(4)`
   returns the new byte buffer with 4 as capacity, therefore `ByteBuffer.allocate(8).order(ByteOrder.LITTLE_ENDIAN).putLong(input).array()`
   returns an array of length 4 */
   @Override
@@ -54,7 +54,7 @@ public HashCode hashInt(int input) {
     return hashBytes(ByteBuffer.allocate(4).order(ByteOrder.LITTLE_ENDIAN).putInt(input).array());
   }
 
-  @SuppressWarnings("value:argument.type.incompatible")/* Since ByteBuffer is a mutable length data structure, `ByteBuffer.allocate(8)`
+  @SuppressWarnings("value:argument") /* Since ByteBuffer is a mutable length data structure, `ByteBuffer.allocate(8)`
   returns the new byte buffer with 8 as capacity, therefore `ByteBuffer.allocate(8).order(ByteOrder.LITTLE_ENDIAN).putLong(input).array()`
   returns an array of length 8 */
   @Override
@@ -62,7 +62,7 @@ public HashCode hashLong(long input) {
     return hashBytes(ByteBuffer.allocate(8).order(ByteOrder.LITTLE_ENDIAN).putLong(input).array());
   }
 
-  @SuppressWarnings("value:argument.type.incompatible") /* Since ByteBuffer is a mutable length data structure and input
+  @SuppressWarnings("value:argument") /* Since ByteBuffer is a mutable length data structure and input
   has min length of 1,`ByteBuffer.allocate(len * 2)` returns the new byte buffer with min length of 2 as capacity,
   therefore ByteBuffer.allocate(len * 2).order(ByteOrder.LITTLE_ENDIAN) returns an array of non negative length */
   @Override
@@ -75,7 +75,7 @@ public HashCode hashUnencodedChars(@MinLen(1) CharSequence input) {
     return hashBytes(buffer.array());
   }
 
-  @SuppressWarnings("value:argument.type.incompatible")//If `input` has min of 1, since `getBytes(charset)`
+  @SuppressWarnings("value:argument") //If `input` has min of 1, since `getBytes(charset)`
   // the resultant byte array, the array returned also has min length of 1
   @Override
   public HashCode hashString(@MinLen(1) CharSequence input, Charset charset) {
@@ -146,7 +146,7 @@ void write(ByteBuffer input) {
       count += remaining;
     }
 
-    @SuppressWarnings("value:return.type.incompatible")//`buf` array in the pre-compiled class `ByteArrayOutputStream`
+    @SuppressWarnings("value:return") //`buf` array in the pre-compiled class `ByteArrayOutputStream`
       // should be annotated as @MinLen(1)
     byte @MinLen(1)[] byteArray() {
       return buf;
diff --git a/guava/src/com/google/common/hash/FarmHashFingerprint64.java b/guava/src/com/google/common/hash/FarmHashFingerprint64.java
index 14cdd90ceaad..c36f72c9bc61 100644
--- a/guava/src/com/google/common/hash/FarmHashFingerprint64.java
+++ b/guava/src/com/google/common/hash/FarmHashFingerprint64.java
@@ -84,10 +84,12 @@ static long fingerprint(byte[] bytes, @NonNegative @LTLengthOf(value = "#1", off
     }
   }
 
+  @SuppressWarnings("signedness:shift.unsigned")
   private static long shiftMix(long val) {
     return val ^ (val >>> 47);
   }
 
+  @SuppressWarnings("signedness:shift.unsigned")
   private static long hashLength16(long u, long v, long mul) {
     long a = (u ^ v) * mul;
     a ^= (a >>> 47);
@@ -119,12 +121,6 @@ private static void weakHashLength32WithSeeds(
     output[1] = seedB + c;
   }
 
-  @SuppressWarnings({"lowerbound:argument.type.incompatible",//(1): if length >= 8 and offset is non negative, offset + length - 8 >= 0.
-          "upperbound:argument.type.incompatible",//(2): if length >= 4 and offset + length - 1 < bytes.length, offset + 4 - 1 < bytes.length.
-          "upperbound:array.access.unsafe.high",/*(3): if 0 < length < 4, therefore offset + length - 1 < bytes.length,
-          offset + length / 2(length >> 2) - 1 < bytes.length and offset + length - 1 - 1 < bytes.length.
-          */
-  })
   private static long hashLength0to16(byte[] bytes, @NonNegative @LTLengthOf(value = "#1", offset = "#3 - 1") int offset, @IntRange(from = 0, to = 16) @LTLengthOf(value = "#1", offset = "#2 - 1") int length) {
     if (length >= 8) {
       long mul = K2 + length * 2;
@@ -150,9 +146,6 @@ private static long hashLength0to16(byte[] bytes, @NonNegative @LTLengthOf(value
     return K2;
   }
 
-  @SuppressWarnings(value = {"lowerbound:argument.type.incompatible"/*(1): if 17 <= length <= 32 and offset is non negative,
-          offset + length - 8 >= 0 and offset + length - 16 >= 0.
-          */})
   private static long hashLength17to32(byte[] bytes, @NonNegative @LTLengthOf(value = "#1", offset = "#3 - 1") int offset, @IntRange(from = 17, to = 32) @LTLengthOf(value = "#1", offset = "#2 - 1") int length) {
     long mul = K2 + length * 2;
     long a = load64(bytes, offset) * K1;
@@ -182,13 +175,6 @@ private static long hashLength33To64(byte[] bytes, @NonNegative  @LTLengthOf(val
   /*
    * Compute an 8-byte hash of a byte array of length greater than 64 bytes.
    */
-  @SuppressWarnings({"lowerbound:assignment.type.incompatible",/*(1): since length >= 65, `end` is non negative,
-  therefore `last64offset` is also non negative. */
-          "upperbound:assignment.type.incompatible",//(1): ?
-          "upperbound:compound.assignment.type.incompatible"/*(2): if length >= 65 and offset < bytes.length - length + 1,
-          offset += 64 < bytes.length.
-          */
-  })
   private static long hashLength65Plus(byte[] bytes, @NonNegative @LTLengthOf(value = "#1", offset = "#3 - 1") int offset, @IntRange(from = 65) @LTLengthOf(value = "#1", offset = "#2 - 1") int length) {
     final int seed = 81;
     // For strings over 64 bytes we loop. Internal state consists of 56 bytes: v, w, x, y, and z.
diff --git a/guava/src/com/google/common/hash/Funnels.java b/guava/src/com/google/common/hash/Funnels.java
index 157a821721d6..75691d8ebbc3 100644
--- a/guava/src/com/google/common/hash/Funnels.java
+++ b/guava/src/com/google/common/hash/Funnels.java
@@ -22,6 +22,7 @@
 import org.checkerframework.checker.index.qual.LTLengthOf;
 import org.checkerframework.checker.index.qual.NonNegative;
 import org.checkerframework.checker.nullness.qual.Nullable;
+import org.checkerframework.checker.signedness.qual.PolySigned;
 import org.checkerframework.common.value.qual.MinLen;
 
 /**
@@ -43,7 +44,7 @@ private enum ByteArrayFunnel implements Funnel<byte[]> {
     INSTANCE;
 
     @Override
-    public void funnel(byte @MinLen(1)[] from, PrimitiveSink into) {
+    public void funnel(byte [] from, PrimitiveSink into) {
       into.putBytes(from);
     }
 
@@ -68,7 +69,7 @@ private enum UnencodedCharsFunnel implements Funnel<CharSequence> {
     INSTANCE;
 
     @Override
-    public void funnel(@MinLen(1) CharSequence from, PrimitiveSink into) {
+    public void funnel(CharSequence from, PrimitiveSink into) {
       into.putUnencodedChars(from);
     }
 
@@ -96,7 +97,7 @@ private static class StringCharsetFunnel implements Funnel<CharSequence>, Serial
     }
 
     @Override
-    public void funnel(@MinLen(1) CharSequence from, PrimitiveSink into) {
+    public void funnel(CharSequence from, PrimitiveSink into) {
       into.putString(from, charset);
     }
 
@@ -250,18 +251,18 @@ private static class SinkAsStream extends OutputStream {
     }
 
     @Override
-    public void write(int b) {
+    public void write(@PolySigned int b) {
       sink.putByte((byte) b);
     }
 
-    @SuppressWarnings("override.param.invalid")//OutputStream#write() should be annotated as void write(byte @MinLen(1)[] bytes)
+    @SuppressWarnings("override.param") // OutputStream#write() should be annotated as void write(byte @MinLen(1)[] bytes)
     @Override
     public void write(byte @MinLen(1)[] bytes) {
       sink.putBytes(bytes);
     }
 
     @Override
-    public void write(byte[] bytes, @NonNegative @LTLengthOf(value = "#1", offset = "#3 - 1") int off, @NonNegative @LTLengthOf(value = "#1", offset = "#2 - 1") int len) {
+    public void write(@PolySigned byte[] bytes, @NonNegative @LTLengthOf(value = "#1", offset = "#3 - 1") int off, @NonNegative @LTLengthOf(value = "#1", offset = "#2 - 1") int len) {
       sink.putBytes(bytes, off, len);
     }
 
diff --git a/guava/src/com/google/common/hash/HashCode.java b/guava/src/com/google/common/hash/HashCode.java
index 99a6b64d6c11..c968589957f3 100644
--- a/guava/src/com/google/common/hash/HashCode.java
+++ b/guava/src/com/google/common/hash/HashCode.java
@@ -256,6 +256,7 @@ public static HashCode fromBytes(byte @MinLen(1)[] bytes) {
    * must be handed-off so as to preserve the immutability contract of {@code HashCode}.
    */
   static HashCode fromBytesNoCopy(byte @MinLen(1)[] bytes) {
+    checkArgument(bytes.length >= 1, "A HashCode must contain at least 1 byte.");
     return new BytesHashCode(bytes);
   }
 
@@ -347,12 +348,7 @@ boolean equalsSameBits(HashCode that) {
    *
    * @since 15.0
    */
-  @SuppressWarnings({"upperbound:argument.type.incompatible",/* (1): `string` min length is 2 and `string.length` must be a even number.
-  Since for loop increment by two each iteration, `i` is always < `string.length - 2` */
-          "upperbound:array.access.unsafe.high",/* Since `bytes.length = string.length / 2` and `i` is incremented by 2, range 0 - string.length()
-          `i / 2` is safe as indexes. */
-          "argument.type.incompatible"//(2) Since `string.length >= 2` and `bytes.length` init is `string.length / 2`, bytes has min length of 1.
-          })
+  @SuppressWarnings("value:argument") // fromBytesNoCopy verfies bytes contains at least 1 byte
   public static HashCode fromString(String string) {
     checkArgument(
         string.length() >= 2, "input string (%s) must have at least 2 characters", string);
diff --git a/guava/src/com/google/common/hash/Hashing.java b/guava/src/com/google/common/hash/Hashing.java
index 1eb6c8674372..36dc19a784b1 100644
--- a/guava/src/com/google/common/hash/Hashing.java
+++ b/guava/src/com/google/common/hash/Hashing.java
@@ -516,7 +516,7 @@ public static int consistentHash(long input, int buckets) {
    * @throws IllegalArgumentException if {@code hashCodes} is empty, or the hash codes do not all
    *     have the same bit length
    */
-  @SuppressWarnings("value:argument.type.incompatible")// `hashCode.asBytes()` return an array with min length of 1.
+  @SuppressWarnings("value:argument")// `hashCode.asBytes()` return an array with min length of 1.
   //Since nextBytes.length is checked to have same bit length with resultBytes.length, resultBytes also needs min length of 1.
   public static HashCode combineOrdered(Iterable<HashCode> hashCodes) {
     Iterator<HashCode> iterator = hashCodes.iterator();
@@ -543,7 +543,7 @@ public static HashCode combineOrdered(Iterable<HashCode> hashCodes) {
    * @throws IllegalArgumentException if {@code hashCodes} is empty, or the hash codes do not all
    *     have the same bit length
    */
-  @SuppressWarnings("value:argument.type.incompatible")// `hashCode.asBytes()` return an array with min length of 1.
+  @SuppressWarnings("value:argument")// `hashCode.asBytes()` return an array with min length of 1.
   //Since nextBytes.length is checked to have same bit length with resultBytes.length, resultBytes also needs min length of 1.
   public static HashCode combineUnordered(Iterable<HashCode> hashCodes) {
     Iterator<HashCode> iterator = hashCodes.iterator();
@@ -561,6 +561,7 @@ public static HashCode combineUnordered(Iterable<HashCode> hashCodes) {
   }
 
   /** Checks that the passed argument is positive, and ceils it to a multiple of 32. */
+  @SuppressWarnings("value:return")// code verifies positive and >= 32
   static @IntRange(from=32) int checkPositiveAndMakeMultipleOf32(int bits) {
     checkArgument(bits > 0, "Number of bits must be positive");
     return (bits + 31) & ~31;
@@ -621,6 +622,7 @@ private ConcatenatedHashFunction(HashFunction... functions) {
     }
 
     @Override
+    @SuppressWarnings("value:argument") // fromBytesNoCopy verfies bytes contains at least 1 byte
     HashCode makeHash(Hasher[] hashers) {
       byte[] bytes = new byte[bits() / 8];
       int i = 0;
@@ -666,6 +668,7 @@ public LinearCongruentialGenerator(long seed) {
       this.state = seed;
     }
 
+    @SuppressWarnings("signedness:shift.unsigned")
     public double nextDouble() {
       state = 2862933555777941757L * state + 1;
       return ((double) ((int) (state >>> 33) + 1)) / 0x1.0p31;
diff --git a/guava/src/com/google/common/hash/LongAdder.java b/guava/src/com/google/common/hash/LongAdder.java
index 674ba4d29965..e47b7366694a 100644
--- a/guava/src/com/google/common/hash/LongAdder.java
+++ b/guava/src/com/google/common/hash/LongAdder.java
@@ -17,6 +17,7 @@
 import java.io.Serializable;
 import java.util.concurrent.atomic.AtomicLong;
 import org.checkerframework.common.value.qual.MinLen;
+import org.checkerframework.common.value.qual.PolyValue;
 
 /**
  * One or more variables that together maintain an initially zero {@code long} sum. When updates
@@ -56,7 +57,7 @@ public LongAdder() {}
    *
    * @param x the value to add
    */
-  @SuppressWarnings("value:assignment.type.incompatible")// if `threadHashCode.get()` return an array of min length < 1,
+  @SuppressWarnings("value:assignment") // if `threadHashCode.get()` return an array of min length < 1,
   // other conditions will be computed.
   @Override
   public void add(long x) {
@@ -158,26 +159,30 @@ public String toString() {
    * @return the sum
    */
   @Override
-  public long longValue() {
-    return sum();
+  @SuppressWarnings("cast.unsafe")
+  public @PolyValue long longValue(@PolyValue LongAdder this) {
+    return (@PolyValue long)sum();
   }
 
   /** Returns the {@link #sum} as an {@code int} after a narrowing primitive conversion. */
   @Override
-  public int intValue() {
-    return (int) sum();
+  @SuppressWarnings("cast.unsafe")
+  public @PolyValue int intValue(@PolyValue LongAdder this) {
+    return (@PolyValue int) sum();
   }
 
   /** Returns the {@link #sum} as a {@code float} after a widening primitive conversion. */
   @Override
-  public float floatValue() {
-    return (float) sum();
+  @SuppressWarnings("cast.unsafe")
+  public @PolyValue float floatValue(@PolyValue LongAdder this) {
+    return (@PolyValue float) sum();
   }
 
   /** Returns the {@link #sum} as a {@code double} after a widening primitive conversion. */
   @Override
-  public double doubleValue() {
-    return (double) sum();
+  @SuppressWarnings("cast.unsafe")
+  public @PolyValue double doubleValue(@PolyValue LongAdder this) {
+    return (@PolyValue double) sum();
   }
 
   private void writeObject(ObjectOutputStream s) throws IOException {
diff --git a/guava/src/com/google/common/hash/MessageDigestHashFunction.java b/guava/src/com/google/common/hash/MessageDigestHashFunction.java
index 97c3a077c1cd..650d63948020 100644
--- a/guava/src/com/google/common/hash/MessageDigestHashFunction.java
+++ b/guava/src/com/google/common/hash/MessageDigestHashFunction.java
@@ -158,7 +158,7 @@ private void checkNotDone() {
       checkState(!done, "Cannot re-use a Hasher after calling hash() on it");
     }
 
-    @SuppressWarnings("value:argument.type.incompatible")/* `bytes` is positive, if `digest.getDigestLength()` returns
+    @SuppressWarnings("value:argument") /* `bytes` is positive, if `digest.getDigestLength()` returns
     a positive and equals to `bytes`, `digest.digest()` returns array with min length of 1.
     */
     @Override
diff --git a/guava/src/com/google/common/hash/PrimitiveSink.java b/guava/src/com/google/common/hash/PrimitiveSink.java
index 68122880e6a8..b737912c8f5a 100644
--- a/guava/src/com/google/common/hash/PrimitiveSink.java
+++ b/guava/src/com/google/common/hash/PrimitiveSink.java
@@ -47,7 +47,7 @@ public interface PrimitiveSink {
    * @param bytes a byte array
    * @return this instance
    */
-  PrimitiveSink putBytes(byte[] bytes);
+  PrimitiveSink putBytes(byte @MinLen(1)[] bytes);
 
   /**
    * Puts a chunk of an array of bytes into this sink. {@code bytes[off]} is the first byte written,
diff --git a/guava/src/com/google/common/io/BaseEncoding.java b/guava/src/com/google/common/io/BaseEncoding.java
index c2a3a4674be5..4bb682503a77 100644
--- a/guava/src/com/google/common/io/BaseEncoding.java
+++ b/guava/src/com/google/common/io/BaseEncoding.java
@@ -40,6 +40,7 @@
 import org.checkerframework.checker.index.qual.LTLengthOf;
 import org.checkerframework.checker.index.qual.NonNegative;
 import org.checkerframework.checker.nullness.qual.Nullable;
+import org.checkerframework.checker.signedness.qual.PolySigned;
 import org.checkerframework.common.value.qual.ArrayLen;
 import org.checkerframework.common.value.qual.MinLen;
 
@@ -434,8 +435,6 @@ private static final class Alphabet {
     private final byte[] decodabet;
     private final boolean[] validPadding;
 
-    @SuppressWarnings({"array.access.unsafe", "assignment.type.incompatible"}) /* c will be a valid index by the time decodabet is accessed with it. validPadding has
-    enough space because the loop stops when i = bytesPerChunk. chars is the same as this.chars, so the assignment of this.mask is safe.*/
     Alphabet(String name, char @MinLen(1) [] chars) {
       this.name = checkNotNull(name);
       this.chars = checkNotNull(chars);
@@ -449,7 +448,6 @@ private static final class Alphabet {
        * e.g. for base64, bitsPerChar == 6, charsPerChunk == 4, and bytesPerChunk == 3. This makes
        * for the smallest chunk size that still has charsPerChunk * bitsPerChar be a multiple of 8.
        */
-      @SuppressWarnings("assignment.type.incompatible") // lowestOneBit cannot return a value with first bit 1 when the value is non-negative
       @NonNegative int gcd = Math.min(8, Integer.lowestOneBit(bitsPerChar));
       try {
         this.charsPerChunk = 8 / gcd;
@@ -481,12 +479,10 @@ char encode(@IndexFor("this.chars") int bits) {
       return chars[bits];
     }
 
-    @SuppressWarnings("array.access.unsafe") // The index used is smaller than charsPerChunk, which is the length of validPadding
     boolean isValidPaddingStartPosition(@NonNegative int index) {
       return validPadding[index % charsPerChunk];
     }
 
-    @SuppressWarnings("array.access.unsafe") // decodabet won't be accessed with an invalid index because a char is greater than 0.
     boolean canDecode(char ch) {
       return ch <= Ascii.MAX && decodabet[ch] != -1;
     }
@@ -548,7 +544,6 @@ Alphabet lowerCase() {
       return new Alphabet(name + ".lowerCase()", lowerCased);
     }
 
-    @SuppressWarnings("array.access.unsafe") // if c is not a valid index for decodabet, the second operand will not be processed.
     public boolean matches(char c) {
       return c < decodabet.length && decodabet[c] != -1;
     }
@@ -593,7 +588,6 @@ static class StandardBaseEncoding extends BaseEncoding {
     }
 
     @Override
-    @SuppressWarnings("return.type.incompatible") // Every operand is non-negative
     @NonNegative int maxEncodedSize(@NonNegative int bytes) {
       return alphabet.charsPerChunk * divide(bytes, alphabet.bytesPerChunk, CEILING);
     }
@@ -608,7 +602,7 @@ public OutputStream encodingStream(final Writer out) {
         int writtenChars = 0;
 
         @Override
-        public void write(int b) throws IOException {
+        public void write(@PolySigned int b) throws IOException {
           bitBuffer <<= 8;
           bitBuffer |= b & 0xFF;
           bitBufferLength += 8;
@@ -644,7 +638,6 @@ public void close() throws IOException {
     }
 
     @Override
-    @SuppressWarnings("argument.type.incompatible") /* The offset and the length have been previously checked and the loop stops before the arguments become invalid*/
     void encodeTo(Appendable target, byte[] bytes, @IndexOrHigh("#2") int off, @NonNegative @LTLengthOf(value = "#2", offset = "#3 - 1") int len) throws IOException {
       checkNotNull(target);
       checkPositionIndexes(off, off + len, bytes.length);
@@ -679,7 +672,6 @@ void encodeChunkTo(Appendable target, byte[] bytes, @IndexOrHigh("#2") int off,
     }
 
     @Override
-    @SuppressWarnings("return.type.incompatible") // Every operand is non-negative
     @NonNegative int maxDecodedSize(@NonNegative int chars) {
       return (int) ((alphabet.bitsPerChar * (long) chars + 7L) / 8L);
     }
@@ -716,8 +708,6 @@ public boolean canDecode(CharSequence chars) {
     }
 
     @Override
-    @SuppressWarnings({"argument.type.incompatible", "array.access.unsafe", "return.type.incompatible"})
-    /* chars will not be accessed with an invalid index because of the loop stop condition. */
     @IndexFor("#1") int decodeTo(byte[] target, CharSequence chars) throws DecodingException {
       checkNotNull(target);
       chars = trimTrailingPadding(chars);
@@ -910,9 +900,6 @@ static final class Base16Encoding extends StandardBaseEncoding {
       this(new Alphabet(name, alphabetChars.toCharArray()));
     }
 
-    @SuppressWarnings({"array.access.unsafe", "argument.type.incompatible"}) /* Since encoding has a length of 512, it is safe to
-    access it with indexes from 0 to 255 and 256 to 511, respectively. The calls to encode are safe because it has been previously
-    verified that the length of chars array is exactly 16*/
     private Base16Encoding(Alphabet alphabet) {
       super(alphabet, null);
       checkArgument(alphabet.chars.length == 16);
@@ -923,7 +910,6 @@ private Base16Encoding(Alphabet alphabet) {
     }
 
     @Override
-    @SuppressWarnings("array.access.unsafe") // encoding has length 512, so it can be accessed with b + 256
     void encodeTo(Appendable target, byte[] bytes, @IndexOrHigh("#2") int off, @NonNegative @LTLengthOf(value = "#2", offset = "#3 - 1") int len) throws IOException {
       checkNotNull(target);
       checkPositionIndexes(off, off + len, bytes.length);
@@ -935,8 +921,6 @@ void encodeTo(Appendable target, byte[] bytes, @IndexOrHigh("#2") int off, @NonN
     }
 
     @Override
-    @SuppressWarnings({"return.type.incompatible", "array.access.unsafe"}) /* bytesWritten grows slower than i, which stops
-    when it exceeds the length of target */
     @IndexFor("#1") int decodeTo(byte[] target, CharSequence chars) throws DecodingException {
       checkNotNull(target);
       if (chars.length() % 2 == 1) {
@@ -944,7 +928,6 @@ void encodeTo(Appendable target, byte[] bytes, @IndexOrHigh("#2") int off, @NonN
       }
       int bytesWritten = 0;
       for (int i = 0; i < chars.length(); i += 2) {
-        @SuppressWarnings("argument.type.incompatible") // a char variable  is a valid index for chars.
         int decoded = alphabet.decode(chars.charAt(i)) << 4 | alphabet.decode(chars.charAt(i + 1));
         target[bytesWritten++] = (byte) decoded;
       }
@@ -968,14 +951,11 @@ private Base64Encoding(Alphabet alphabet, @Nullable Character paddingChar) {
     }
 
     @Override
-    @SuppressWarnings("argument.type.incompatible") /* i is between off and off + len, so the last method call is safe.
-    alphabet.chars has length 64, all arguments of encode() are 6-bits long */
     void encodeTo(Appendable target, byte[] bytes, @IndexOrHigh("#2") int off, @NonNegative @LTLengthOf(value = "#2", offset = "#3 - 1") int len) throws IOException {
       checkNotNull(target);
       checkPositionIndexes(off, off + len, bytes.length);
       int i = off;
       for (int remaining = len; remaining >= 3; remaining -= 3) {
-        @SuppressWarnings("array.access.unsafe") // i is a valid index because the parameters have been checked
         int chunk = (bytes[i++] & 0xFF) << 16 | (bytes[i++] & 0xFF) << 8 | bytes[i++] & 0xFF;
         target.append(alphabet.encode(chunk >>> 18));
         target.append(alphabet.encode((chunk >>> 12) & 0x3F));
@@ -988,9 +968,6 @@ void encodeTo(Appendable target, byte[] bytes, @IndexOrHigh("#2") int off, @NonN
     }
 
     @Override
-    @SuppressWarnings({"argument.type.incompatible", "array.access.unsafe", "return.type.incompatible"})
-    /* i will be a valid index for chars because it is verified at every step. charAt() returns a char value, which is known to be
-    a valid index for alphabet. bytesWritten grows just like variable i, so it will not exceed the length of chars. */
     @IndexFor("#1") int decodeTo(byte[] target, CharSequence chars) throws DecodingException {
       checkNotNull(target);
       chars = trimTrailingPadding(chars);
@@ -1084,6 +1061,7 @@ static Writer separatingWriter(
         separatingAppendable(delegate, separator, afterEveryChars);
     return new Writer() {
       @Override
+      @SuppressWarnings("signedness:cast.unsafe")  // can't prove c fits in a char???
       public void write(int c) throws IOException {
         separatingAppendable.append((char) c);
       }
@@ -1124,7 +1102,6 @@ CharSequence trimTrailingPadding(CharSequence chars) {
     }
 
     @Override
-    @SuppressWarnings("return.type.incompatible") // Every operand in the return expression is non-negative
     @NonNegative int maxEncodedSize(@NonNegative int bytes) {
       int unseparatedSize = delegate.maxEncodedSize(bytes);
       return unseparatedSize
diff --git a/guava/src/com/google/common/io/ByteSource.java b/guava/src/com/google/common/io/ByteSource.java
index 330860d27966..bb9e171e3b42 100644
--- a/guava/src/com/google/common/io/ByteSource.java
+++ b/guava/src/com/google/common/io/ByteSource.java
@@ -544,7 +544,7 @@ public boolean isEmpty() throws IOException {
     }
 
     @Override
-    @SuppressWarnings("return.type.incompatible") // off is at most equal to unslicedSize and length is non-negative
+    @SuppressWarnings("value:return") // off is at most equal to unslicedSize and length is non-negative
     public Optional<@NonNegative Long> sizeIfKnown() {
       Optional<@NonNegative Long> optionalUnslicedSize = ByteSource.this.sizeIfKnown();
       if (optionalUnslicedSize.isPresent()) {
@@ -571,8 +571,6 @@ private static class ByteArrayByteSource extends ByteSource {
       this(bytes, 0, bytes.length);
     }
 
-    // NOTE: Preconditions are enforced by slice, the only non-trivial caller.
-    @SuppressWarnings("assignment.type.incompatible") /* bytes is the same as this.bytes, and offset is the same as this.offset */
     ByteArrayByteSource(byte[] bytes, @IndexOrHigh("#1") int offset, @NonNegative @LTLengthOf(value = "#1", offset = "#2 - 1") int length) {
       this.bytes = bytes;
       this.offset = offset;
@@ -628,8 +626,6 @@ public HashCode hash(HashFunction hashFunction) throws IOException {
     }
 
     @Override
-    @SuppressWarnings({"assignment.type.incompatible", "argument.type.incompatible"}) /* length is valid because offset
-     is smaller than the this.length */
     public ByteSource slice(@NonNegative long offset, @NonNegative long length) {
       checkArgument(offset >= 0, "offset (%s) may not be negative", offset);
       checkArgument(length >= 0, "length (%s) may not be negative", length);
@@ -697,7 +693,7 @@ public boolean isEmpty() throws IOException {
     }
 
     @Override
-    @SuppressWarnings("return.type.incompatible") // Long.MAX_VALUE is non-negative
+    @SuppressWarnings("value:return") // Long.MAX_VALUE is non-negative
     public Optional<@NonNegative Long> sizeIfKnown() {
       if (!(sources instanceof Collection)) {
         // Infinite Iterables can cause problems here. Of course, it's true that most of the other
diff --git a/guava/src/com/google/common/io/ByteStreams.java b/guava/src/com/google/common/io/ByteStreams.java
index 201b6323c3cc..9809a873d660 100644
--- a/guava/src/com/google/common/io/ByteStreams.java
+++ b/guava/src/com/google/common/io/ByteStreams.java
@@ -47,6 +47,7 @@
 import org.checkerframework.checker.index.qual.LTLengthOf;
 import org.checkerframework.checker.index.qual.LessThan;
 import org.checkerframework.checker.index.qual.NonNegative;
+import org.checkerframework.checker.signedness.qual.PolySigned;
 import java.util.Deque;
 import java.util.Queue;
 
@@ -204,8 +205,6 @@ private static byte[] toByteArrayInternal(InputStream in, Queue<byte[]> bufs, @N
     }
   }
 
-  @SuppressWarnings("argument.type.incompatible") /* resultOffset is greater than 0 because remaining gets closer to 0
-  totalLen stays the same. bytesToCopy is valid because it can't exceed the length of buf */
   private static byte[] combineBuffers(Queue<byte[]> bufs, @NonNegative int totalLen) {
     byte[] result = new byte[totalLen];
     int remaining = totalLen;
@@ -246,10 +245,7 @@ static byte[] toByteArray(InputStream in, @NonNegative long expectedSize) throws
     @LessThan("expectedSize + 1") int remaining = (int) expectedSize;
 
     while (remaining > 0) {
-      @SuppressWarnings("assignment.type.incompatible") /* off can't go below 0 because remaining doesn't get bigger,
-      only smaller. It can't go beyond an index for bytes because the loop stops when remaining is negative */
       @IndexOrHigh("bytes") int off = (int) expectedSize - remaining;
-      @SuppressWarnings("argument.type.incompatible") /* off + remaining is at most expectedSize, which is the size of bytes. */
       int read = in.read(bytes, off, remaining);
       if (read == -1) {
         // end of stream before reading expectedSize bytes
@@ -307,8 +303,6 @@ public static ByteArrayDataInput newDataInput(byte[] bytes) {
    *     the array
    */
   @Beta
-  @SuppressWarnings("argument.type.incompatible") /* bytes.length - start is a correct length for the array because start
-  is smaller than bytes.length and it doesn't exceed bytes.length when start is added as offset.*/
   public static ByteArrayDataInput newDataInput(byte[] bytes, @IndexOrHigh("#1") int start) {
     checkPositionIndex(start, bytes.length);
     return newDataInput(new ByteArrayInputStream(bytes, start, bytes.length - start));
@@ -656,17 +650,17 @@ public byte[] toByteArray() {
       new OutputStream() {
         /** Discards the specified byte. */
         @Override
-        public void write(int b) {}
+        public void write(@PolySigned int b) {}
 
         /** Discards the specified byte array. */
         @Override
-        public void write(byte[] b) {
+        public void write(@PolySigned byte[] b) {
           checkNotNull(b);
         }
 
         /** Discards the specified byte array. */
         @Override
-        public void write(byte[] b, @IndexOrHigh("#1") int off, @NonNegative @LTLengthOf(value = "#1", offset = "#2 - 1") int len) {
+        public void write(@PolySigned byte[] b, @IndexOrHigh("#1") int off, @NonNegative @LTLengthOf(value = "#1", offset = "#2 - 1") int len) {
           checkNotNull(b);
         }
 
@@ -724,7 +718,6 @@ public synchronized void mark(@NonNegative int readLimit) {
     }
 
     @Override
-    @SuppressWarnings("compound.assignment.type.incompatible") /* left can't go below 0 because it was previously checked*/
     public @GTENegativeOne int read() throws IOException {
       if (left == 0) {
         return -1;
@@ -752,7 +745,6 @@ public synchronized void mark(@NonNegative int readLimit) {
     }
 
     @Override
-    @SuppressWarnings("assignment.type.incompatible") /* mark is surely non-negative because of the check before*/
     public synchronized void reset() throws IOException {
       if (!in.markSupported()) {
         throw new IOException("Mark not supported");
@@ -935,8 +927,6 @@ public static int read(InputStream in, byte[] b, @IndexOrHigh("#2") int off, @No
     checkPositionIndexes(off, off + len, b.length);
     int total = 0;
     while (total < len) {
-      @SuppressWarnings("argument.type.incompatible") /* if the offset and length passed to this method are invalid,
-      an exception would be thrown anyways, so there is no need to check them before */
       int result = in.read(b, off + total, len - total);
       if (result == -1) {
         break;
diff --git a/guava/src/com/google/common/io/FileBackedOutputStream.java b/guava/src/com/google/common/io/FileBackedOutputStream.java
index ab687adb180c..51a6a04e2939 100644
--- a/guava/src/com/google/common/io/FileBackedOutputStream.java
+++ b/guava/src/com/google/common/io/FileBackedOutputStream.java
@@ -58,7 +58,7 @@ public final class FileBackedOutputStream extends OutputStream {
   private final int fileThreshold;
   private final boolean resetOnFinalize;
   private final ByteSource source;
-  @Nullable private final File parentDirectory;
+  private final @Nullable File parentDirectory;
 
   @GuardedBy("this")
   private OutputStream out;
@@ -75,7 +75,6 @@ byte[] getBuffer() {
       return buf;
     }
 
-    @SuppressWarnings("return.type.incompatible") // this.getBuffer() is the same as this.buf
     @IndexOrHigh("this.getBuffer()") int getCount() {
       return count;
     }
diff --git a/guava/src/com/google/common/math/LongMath.java b/guava/src/com/google/common/math/LongMath.java
index aea5f914337a..d80056ce6af0 100644
--- a/guava/src/com/google/common/math/LongMath.java
+++ b/guava/src/com/google/common/math/LongMath.java
@@ -38,6 +38,7 @@
 import org.checkerframework.checker.index.qual.LTLengthOf;
 import org.checkerframework.checker.index.qual.NonNegative;
 import org.checkerframework.checker.index.qual.Positive;
+import org.checkerframework.checker.signedness.qual.Unsigned;
 import org.checkerframework.common.value.qual.IntRange;
 import org.checkerframework.common.value.qual.MinLen;
 
@@ -110,9 +111,7 @@ public static boolean isPowerOfTwo(long x) {
    * signed long. The implementation is branch-free, and benchmarks suggest it is measurably faster
    * than the straightforward ternary expression.
    */
-  @SuppressWarnings("value:return.type.incompatible")/* An int has 64 bits, the lestmost bit is 0 for positive values, and is 1 for negative values.
-  For shift right zero fill operator( >>> ), the left operands value is moved right by the number of bits specified by the right operand
-  and shifted values are filled up with zeros. Therefore if x > y, (x - y) return a positive value, when being shifted 63 bits, it returns 0, otherwise return 1. */
+  @SuppressWarnings("signedness:shift.unsigned")
   @VisibleForTesting
   static @IntRange(from = 0, to = 1) int lessThanBranchFree(long x, long y) {
     // Returns the sign bit of x - y.
@@ -147,6 +146,7 @@ public static int log2(long x, RoundingMode mode) {
       case HALF_EVEN:
         // Since sqrt(2) is irrational, log2(x) - logFloor cannot be exactly 0.5
         int leadingZeros = Long.numberOfLeadingZeros(x);
+        @SuppressWarnings("signedness:shift.unsigned")
         long cmp = MAX_POWER_OF_SQRT2_UNSIGNED >>> leadingZeros;
         // floor(2^(logFloor + 0.5))
         int logFloor = (Long.SIZE - 1) - leadingZeros;
@@ -195,20 +195,6 @@ public static int log10(@Positive long x, RoundingMode mode) {
   }
 
   @GwtIncompatible // TODO
-  @SuppressWarnings(value = {"lowerbound:return.type.incompatible",/* (2): `log10Floor()` returns a negative value if y is 0 and
-  `lessThanBranchFree(x, powersOf10[y])` returns 1( when x < powersOf10[y]). Since x is positive, y is 0 when 0 < x < 8( the array `maxLog10ForLeadingZeros` has 0 values at indexes: 61, 62, 63).
-  Since when 0 < x < 8, y is 0 and powersOf10[0] is 1, x can't be < `powersOf10[y]`, therefore `log10Floor()` won't return
-  a negative value. */
-          "upperbound:return.type.incompatible",/*(2) powersOf10.length is 19 and largest element in `maxLog10ForLeadingZeros` is 19 at index 0.
-          Since `log10Floor()` is a static method and only called by methods that take in positive `x` values, `Long.numberOfLeadingZeros(x)`
-          won't return 0 and cause an error */
-          "upperbound:assignment.type.incompatible",/*(2): except for element at index 0 in `maxLog10ForLeadingZeros`, the rest
-          can be indexed for `powersOf10` */
-          "upperbound:array.access.unsafe.high.range"/*(1): `Long.numberOfLeadingZeros(x)` can return an int range from 0 to 64,
-          therfore the array `maxLog10ForLeadingZeros` should have min length of 65. However, since param `x` is required to
-          be positive, the highest int from `Long.numberOfLeadingZeros(x)` is 63.
-          */
-          })
   static @IndexFor(value = {"powersOf10", "halfPowersOf10"}) int log10Floor(@Positive long x) {
     /*
      * Based on Hacker's Delight Fig. 11-5, the two-table-lookup, branch-free implementation.
@@ -289,7 +275,6 @@ public static int log10(@Positive long x, RoundingMode mode) {
    *
    * @throws IllegalArgumentException if {@code k < 0}
    */
-  @SuppressWarnings("index") // https://github.com/typetools/checker-framework/issues/2541
   @GwtIncompatible // TODO
   public static long pow(long b, int k) {
     checkNonNegative("exponent", k);
@@ -624,7 +609,6 @@ public static long checkedMultiply(long a, long b) {
    * @throws ArithmeticException if {@code b} to the {@code k}th power overflows in signed {@code
    *     long} arithmetic
    */
-  @SuppressWarnings("index") // https://github.com/typetools/checker-framework/issues/2541
   @GwtIncompatible // TODO
   public static long checkedPow(long b, int k) {
     checkNonNegative("exponent", k);
@@ -674,6 +658,7 @@ public static long checkedPow(long b, int k) {
    * @since 20.0
    */
   @Beta
+  @SuppressWarnings("signedness:shift.unsigned")
   public static long saturatedAdd(long a, long b) {
     long naiveSum = a + b;
     if ((a ^ b) < 0 | (a ^ naiveSum) >= 0) {
@@ -692,6 +677,7 @@ public static long saturatedAdd(long a, long b) {
    * @since 20.0
    */
   @Beta
+  @SuppressWarnings("signedness:shift.unsigned")
   public static long saturatedSubtract(long a, long b) {
     long naiveDifference = a - b;
     if ((a ^ b) >= 0 | (a ^ naiveDifference) >= 0) {
@@ -721,6 +707,7 @@ public static long saturatedMultiply(long a, long b) {
       return a * b;
     }
     // the return value if we will overflow (which we calculate by overflowing a long :) )
+    @SuppressWarnings("signedness:shift.unsigned")
     long limit = Long.MAX_VALUE + ((a ^ b) >>> (Long.SIZE - 1));
     if (leadingZeros < Long.SIZE | (a < 0 & b == Long.MIN_VALUE)) {
       // overflow
@@ -739,7 +726,6 @@ public static long saturatedMultiply(long a, long b) {
    *
    * @since 20.0
    */
-  @SuppressWarnings("index") // https://github.com/typetools/checker-framework/issues/2541
   @Beta
   public static long saturatedPow(long b, int k) {
     checkNonNegative("exponent", k);
@@ -767,6 +753,7 @@ public static long saturatedPow(long b, int k) {
     }
     long accum = 1;
     // if b is negative and k is odd then the limit is MIN otherwise the limit is MAX
+    @SuppressWarnings("signedness:shift.unsigned")
     long limit = Long.MAX_VALUE + ((b >>> Long.SIZE - 1) & (k & 1));
     while (true) {
       switch (k) {
@@ -833,9 +820,6 @@ public static long factorial(@NonNegative int n) {
    *
    * @throws IllegalArgumentException if {@code n < 0}, {@code k < 0}, or {@code k > n}
    */
-  @SuppressWarnings({"lowerbound:unary.decrement.type.incompatible", // k = n - k is non-negative
-                    "array.access.unsafe.low" // looks like a bug, possibly related to the above
-                    })
   public static long binomial(@NonNegative @LTLengthOf("this.factorials") int n, @NonNegative @LessThan("#1 + 1") int k) {
     checkNonNegative("n", n);
     checkNonNegative("k", k);
@@ -1070,7 +1054,7 @@ public static boolean isPrime(long n) {
       return true;
     }
 
-    for (long[] baseSet : millerRabinBaseSets) {
+    for (@Unsigned long[] baseSet : millerRabinBaseSets) {
       if (n <= baseSet[0]) {
         for (int i = 1; i < baseSet.length; i++) {
           if (!MillerRabinTester.test(baseSet[i], n)) {
@@ -1090,7 +1074,7 @@ public static boolean isPrime(long n) {
    * NOTE: We could get slightly better bases that would be treated as unsigned, but benchmarks
    * showed negligible performance improvements.
    */
-  private static final long[] @MinLen(1)[] millerRabinBaseSets = {
+  private static final @Unsigned long[] @MinLen(1)[] millerRabinBaseSets = {
     {291830, 126401071349994536L},
     {885594168, 725270293939359937L, 3569819667048198375L},
     {273919523040L, 15, 7363882082L, 992620450144556L},
@@ -1119,7 +1103,7 @@ private enum MillerRabinTester {
     /** Works for inputs ≤ FLOOR_SQRT_MAX_LONG. */
     SMALL {
       @Override
-      long mulMod(long a, long b, long m) {
+      @Unsigned long mulMod(@Unsigned long a, @Unsigned long b, @Unsigned long m) {
         /*
          * lowasser, 2015-Feb-12: Benchmarks suggest that changing this to UnsignedLongs.remainder
          * and increasing the threshold to 2^32 doesn't pay for itself, and adding another enum
@@ -1130,19 +1114,19 @@ long mulMod(long a, long b, long m) {
       }
 
       @Override
-      long squareMod(long a, long m) {
+      @Unsigned long squareMod(@Unsigned long a, @Unsigned long m) {
         return (a * a) % m;
       }
     },
     /** Works for all nonnegative signed longs. */
     LARGE {
       /** Returns (a + b) mod m. Precondition: {@code 0 <= a}, {@code b < m < 2^63}. */
-      private long plusMod(long a, long b, long m) {
+      private @Unsigned long plusMod(@Unsigned long a, @Unsigned long b, @Unsigned long m) {
         return (a >= m - b) ? (a + b - m) : (a + b);
       }
 
       /** Returns (a * 2^32) mod m. a may be any unsigned long. */
-      private long times2ToThe32Mod(long a, long m) {
+      private @Unsigned long times2ToThe32Mod(@Unsigned long a, @Unsigned long m) {
         int remainingPowersOf2 = 32;
         do {
           int shift = Math.min(remainingPowersOf2, Long.numberOfLeadingZeros(a));
@@ -1155,7 +1139,7 @@ private long times2ToThe32Mod(long a, long m) {
       }
 
       @Override
-      long mulMod(long a, long b, long m) {
+      @Unsigned long mulMod(@Unsigned long a, @Unsigned long b, @Unsigned long m) {
         long aHi = a >>> 32; // < 2^31
         long bHi = b >>> 32; // < 2^31
         long aLo = a & 0xFFFFFFFFL; // < 2^32
@@ -1169,7 +1153,7 @@ long mulMod(long a, long b, long m) {
          * unsigned long, we don't have to do a mod on every operation, only when intermediate
          * results can exceed 2^63.
          */
-        long result = times2ToThe32Mod(aHi * bHi /* < 2^62 */, m); // < m < 2^63
+        @Unsigned long result = times2ToThe32Mod(aHi * bHi /* < 2^62 */, m); // < m < 2^63
         result += aHi * bLo; // aHi * bLo < 2^63, result < 2^64
         if (result < 0) {
           result = UnsignedLongs.remainder(result, m);
@@ -1181,7 +1165,7 @@ long mulMod(long a, long b, long m) {
       }
 
       @Override
-      long squareMod(long a, long m) {
+      @Unsigned long squareMod(@Unsigned long a, @Unsigned long m) {
         long aHi = a >>> 32; // < 2^31
         long aLo = a & 0xFFFFFFFFL; // < 2^32
 
@@ -1204,21 +1188,21 @@ long squareMod(long a, long m) {
       }
     };
 
-    static boolean test(long base, long n) {
+    static boolean test(@Unsigned long base, @Unsigned long n) {
       // Since base will be considered % n, it's okay if base > FLOOR_SQRT_MAX_LONG,
       // so long as n <= FLOOR_SQRT_MAX_LONG.
       return ((n <= FLOOR_SQRT_MAX_LONG) ? SMALL : LARGE).testWitness(base, n);
     }
 
     /** Returns a * b mod m. */
-    abstract long mulMod(long a, long b, long m);
+    abstract @Unsigned long mulMod(@Unsigned long a, @Unsigned long b, @Unsigned long m);
 
     /** Returns a^2 mod m. */
-    abstract long squareMod(long a, long m);
+    abstract @Unsigned long squareMod(@Unsigned long a, @Unsigned long m);
 
     /** Returns a^p mod m. */
-    private long powMod(long a, long p, long m) {
-      long res = 1;
+    private @Unsigned long powMod(@Unsigned long a, @Unsigned long p, @Unsigned long m) {
+      @Unsigned long res = 1;
       for (; p != 0; p >>= 1) {
         if ((p & 1) != 0) {
           res = mulMod(res, a, m);
@@ -1229,7 +1213,7 @@ private long powMod(long a, long p, long m) {
     }
 
     /** Returns true if n is a strong probable prime relative to the specified base. */
-    private boolean testWitness(long base, long n) {
+    private boolean testWitness(@Unsigned long base, @Unsigned long n) {
       int r = Long.numberOfTrailingZeros(n - 1);
       long d = (n - 1) >> r;
       base %= n;
@@ -1237,7 +1221,7 @@ private boolean testWitness(long base, long n) {
         return true;
       }
       // Calculate a := base^d mod n.
-      long a = powMod(base, d, n);
+      @Unsigned long a = powMod(base, d, n);
       // n passes this test if
       //    base^d = 1 (mod n)
       // or base^(2^j * d) = -1 (mod n) for some 0 <= j < r.
diff --git a/guava/src/com/google/common/math/Quantiles.java b/guava/src/com/google/common/math/Quantiles.java
index b05afa4b17c8..cd8a424443b3 100644
--- a/guava/src/com/google/common/math/Quantiles.java
+++ b/guava/src/com/google/common/math/Quantiles.java
@@ -207,7 +207,7 @@ public ScaleAndIndexes indexes(@NonNegative int @MinLen(1)... indexes) {
      *     set will be snapshotted when this method is called
      * @throws IllegalArgumentException if {@code indexes} is empty
      */
-    @SuppressWarnings({"value:argument.type.incompatible", "lowerbound:argument.type.incompatible"})//parameter `indexes` is of mutable length data structures(Collection)
+    @SuppressWarnings("value:argument") // parameter `indexes` is of mutable length data structures(Collection)
     public ScaleAndIndexes indexes(Collection<Integer> indexes) {
       return new ScaleAndIndexes(scale, Ints.toArray(indexes));
     }
@@ -238,7 +238,7 @@ private ScaleAndIndex(@Positive int scale, @NonNegative int index) {
      *     this call (it is copied instead)
      * @return the quantile value
      */
-    @SuppressWarnings("value:argument.type.incompatible")// `dataset` is of mutable length data structures type( `Collection`)
+    @SuppressWarnings("value:argument") // `dataset` is of mutable length data structures type( `Collection`)
     //if `dataset` is not empty as specified in doc, method `Doubles.toArray()` return a non empty `dataset` as well
     public double compute(Collection<? extends Number> dataset) {
       return computeInPlace(Doubles.toArray(dataset));
@@ -285,12 +285,6 @@ public double compute(int @MinLen(1)... dataset) {
      *     be arbitrarily reordered by this method call
      * @return the quantile value
      */
-    @SuppressWarnings({"lowerbound:assignment.type.incompatible",// (0): Since index and (dataset.length - 1) are non-negative ints, numerator is non negative.
-            "upperbound:argument.type.incompatible", "upperbound:array.access.unsafe.high",/* (1): second argument in selectInPlace() is `dataset`,
-            therefore `quotient + 1` should be < dataset.length. If remainder is not zero,
-            quotient max value is `dataset.length - 2`*/
-            "upperbound:assignment.type.incompatible"/*(3) Since `numerator = index * (dataset.length - 1)`,
-            dividing it to scale will return a value less than dataset.length. */})
     public double computeInPlace(double @MinLen(1)... dataset) {
       checkArgument(dataset.length > 0, "Cannot calculate quantiles of an empty dataset");
       if (containsNaN(dataset)) {
@@ -352,7 +346,7 @@ private ScaleAndIndexes(int scale, @NonNegative int @MinLen(1)[] indexes) {
      *     indexes} method.
      */
 
-    @SuppressWarnings("value:argument.type.incompatible")// `dataset` is of mutable length data structures type( `Collection`)
+    @SuppressWarnings("value:argument") // `dataset` is of mutable length data structures type( `Collection`)
     //if `dataset` is not empty as specified in doc, method `Doubles.toArray()` return a non empty `dataset` as well
     public Map<Integer, Double> compute(Collection<? extends Number> dataset) {
       return computeInPlace(Doubles.toArray(dataset));
@@ -411,19 +405,6 @@ public Map<Integer, Double> compute(int @MinLen(1)... dataset) {
      *     map are ordered by quantile index in the same order that the indexes were passed to the
      *     {@code indexes} method.
      */
-    @SuppressWarnings({"upperbound:compound.assignment.type.incompatible",/* (1): Since `requiredSelections.length = indexes.length * 2`, and the for loop
-            iterate from 0 to indexes.length, increment on requiredSelectionsCount is safe thoughout the loop.
-            */
-            "lowerbound:argument.type.incompatible", "upperbound:argument.type.incompatible",/* (2): Since `indexes` is annotated to have at least length of 1,
-            `requiredSelections.length` will be at least 2, therefore larger than constant 0. */
-            "lowerbound:assignment.type.incompatible",/*(3): numerator is = (long) indexes[i] * (dataset.length - 1). Since indexes[i] are non negative
-            dataset has min length of 1, numerator is non negative */
-            "upperbound:assignment.type.incompatible",/* (3): Since scale is a positive int, index is in [0, scale],
-            and (dataset.length - 1) is non-negative int, we can do long-arithmetic on index * (dataset.length - 1) / scale to get a rounded ratio and a remainder
-             which can be expressed as ints, without risk of overflow */
-        "upperbound:array.access.unsafe.high", // (4) if `remainder` is not 0, highest possible value for quotient is `dataset.length - 2`
-        "unary.increment.type.incompatible"
-    })
     public Map<Integer, Double> computeInPlace(double @MinLen(1)... dataset) {
       checkArgument(dataset.length > 0, "Cannot calculate quantiles of an empty dataset");
       if (containsNaN(dataset)) {
@@ -557,9 +538,6 @@ private static void checkIndex(int index, int scale) {
    * ({@code required}, {@code to}] are greater than or equal to that value. Therefore, the value at
    * {@code required} is the value which would appear at that index in the sorted dataset.
    */
-  @SuppressWarnings(value = {"lowerbound:assignment.type.incompatible",/*(1): When entering the loop,
-          required > from and from >= 0, therefore required >= 1.
-          At the assignment, partitionPoint >= required, therefore partitionPoint - 1 >= 0. */})
   private static void selectInPlace(@IndexFor("#2") int required, double[] array, @IndexFor("#2") int from, @IndexFor("#2") int to) {
     // If we are looking for the least element in the range, we can just do a linear search for it.
     // (We will hit this whenever we are doing quantile interpolation: our first selection finds
@@ -599,9 +577,6 @@ private static void selectInPlace(@IndexFor("#2") int required, double[] array,
    * equal to the value at {@code ret} and the values with indexes in ({@code ret}, {@code to}] are
    * greater than or equal to that.
    */
-  @SuppressWarnings("lowerbound:unary.decrement.type.incompatible")/*(1): Both partitionPoint and i are initialized to the same value `to`.
-  partitionPoint is decremented at most one more time than i is decremented, therefore partitionPoint >= i-1.
-  i > from, therefore partitionPoint >= from. Since from is non-negative, therefore partitionPoint is non-negative. */
   private static @IndexFor("#1") int partition(double[] array, @IndexFor("#1") int from, @IndexFor("#1") int to) {
     // Select a pivot, and move it to the start of the slice i.e. to index from.
     movePivotToStartOfSlice(array, from, to);
@@ -654,14 +629,6 @@ private static void movePivotToStartOfSlice(double[] array, @IndexFor("#1") int
    * allRequired[i]} for {@code i} in the range [{@code requiredFrom}, {@code requiredTo}]. These
    * indexes must be sorted in the array and must all be in the range [{@code from}, {@code to}].
    */
-  @SuppressWarnings({"lowerbound:argument.type.incompatible",/*(1): Since allRequired is sorted, and requiredBelow < requiredChosen,
-  allRequired[requiredBelow] <= allRequired[requiredChosen], therefore allRequired[requiredBelow] is always <= required. Based on the condition
-  of if and while, allRequired[requiredBelow] != required. Because allRequired[requiredBelow] <= required, we know that allRequired[requiredBelow] < required,
-  since allRequired[requiredBelow] >= 0, then required > 0. */
-          "upperbound:argument.type.incompatible"/*(2): Since allRequired is sorted, and requiredAbove > requiredChosen,
-  allRequired[requiredAbove] >= allRequired[requiredChosen], therefore allRequired[requiredAbove] is always >= required. Based on the condition
-  of if and while, allRequired[requiredAbove] != required. Because allRequired[requiredAbove] >= required, we know that allRequired[requiredAbove] > required,
-  since array.length > allRequired[requiredAbove] > required, required + 1 < array.length. */})
   private static void selectAllInPlace(
       @IndexFor("#4") int[] allRequired, @IndexFor("#1") int requiredFrom, @IndexFor("#1") int requiredTo, double[] array, @IndexFor("#4") int from, @IndexFor("#4") int to) {
     // Choose the first selection to do...
@@ -700,7 +667,7 @@ private static void selectAllInPlace(
    * minimizes the size of the subranges from which the remaining selections must be done.
    */
   private static @IndexFor("#1") int chooseNextSelection(
-      int[] allRequired, @IndexFor("#1") int requiredFrom, @IndexFor("#1") int requiredTo, int from, int to) {
+      int[] allRequired, @IndexFor("#1") int requiredFrom, @IndexFor("#1") int requiredTo, @NonNegative int from, @NonNegative int to) {
     if (requiredFrom == requiredTo) {
       return requiredFrom; // only one thing to choose, so choose it
     }
diff --git a/guava/src/com/google/common/primitives/Ints.java b/guava/src/com/google/common/primitives/Ints.java
index 4eec9a632934..7da68b484f7a 100644
--- a/guava/src/com/google/common/primitives/Ints.java
+++ b/guava/src/com/google/common/primitives/Ints.java
@@ -111,7 +111,6 @@ public static int checkedCast(@IntRange(from = Integer.MIN_VALUE, to = Integer.M
    *     {@link Integer#MAX_VALUE} if it is too large, or {@link Integer#MIN_VALUE} if it is too
    *     small
    */
-  @SuppressWarnings("lowerbound:return.type.incompatible") // https://github.com/kelloggm/checker-framework/issues/190
   public static @PolyLowerBound int saturatedCast(@PolyLowerBound long value) {
     if (value > Integer.MAX_VALUE) {
       return Integer.MAX_VALUE;
@@ -186,7 +185,6 @@ public static boolean contains(int[] array, int target) {
    * @param array the array to search for the sequence {@code target}
    * @param target the array to search for as a sub-sequence of {@code array}
    */
-  @SuppressWarnings("substringindex:return.type.incompatible") // https://github.com/kelloggm/checker-framework/issues/206 https://github.com/kelloggm/checker-framework/issues/207 https://github.com/kelloggm/checker-framework/issues/208
   public static @LTEqLengthOf("#1") @SubstringIndexFor(value = "#1", offset="#2.length - 1") int indexOf(int[] array, int[] target) {
     checkNotNull(array, "array");
     checkNotNull(target, "target");
@@ -302,7 +300,6 @@ public static int constrainToRange(int value, int min, int max) {
    * pos is increased the same way as length, so pos points to a valid
    * range of length array.length in result.
    */
-  @SuppressWarnings("upperbound:argument.type.incompatible") // sum of lengths
   public static int[] concat(int[]... arrays) {
     int length = 0;
     for (int[] array : arrays) {
@@ -595,8 +592,6 @@ private static class IntArrayAsList extends AbstractList<Integer>
       this(array, 0, array.length);
     }
 
-    @SuppressWarnings(
-            "index") // these three fields need to be initialized in some order, and any ordering leads to the first two issuing errors - since each field is dependent on at least one of the others
     IntArrayAsList(int @MinLen(1)[] array, @IndexFor("#1") @LessThan("#3") int start, @IndexOrHigh("#1") int end) {
       this.array = array;
       this.start = start;
@@ -625,14 +620,14 @@ public Spliterator.OfInt spliterator() {
     }
 
     @Override
+    @SuppressWarnings("signedness:argument") // passing @UnknownSignedness Integer to @Signed int
     public boolean contains(Object target) {
       // Overridden to prevent a ton of boxing
       return (target instanceof Integer) && Ints.indexOf(array, (Integer) target, start, end) != -1;
     }
 
     @Override
-    @SuppressWarnings(
-            "lowerbound:return.type.incompatible") // needs https://github.com/kelloggm/checker-framework/issues/227 on static indexOf method
+    @SuppressWarnings("signedness:argument") // passing @UnknownSignedness Integer to @Signed int
     public @IndexOrLow("this") int indexOf(Object target) {
       // Overridden to prevent a ton of boxing
       if (target instanceof Integer) {
@@ -645,8 +640,7 @@ public boolean contains(Object target) {
     }
 
     @Override
-    @SuppressWarnings(
-            "lowerbound:return.type.incompatible") // needs https://github.com/kelloggm/checker-framework/issues/227 on static indexOf method
+    @SuppressWarnings("signedness:argument") // passing @UnknownSignedness Integer to @Signed int
     public @IndexOrLow("this")int lastIndexOf(Object target) {
       // Overridden to prevent a ton of boxing
       if (target instanceof Integer) {
@@ -668,7 +662,6 @@ public Integer set(@IndexFor("this") int index, Integer element) {
     }
 
     @Override
-    @SuppressWarnings("index") // needs https://github.com/kelloggm/checker-framework/issues/229
     public List<Integer> subList(@IndexOrHigh("this") int fromIndex, @IndexOrHigh("this") int toIndex) {
       int size = size();
       checkPositionIndexes(fromIndex, toIndex, size);
diff --git a/guava/src/com/google/common/primitives/Longs.java b/guava/src/com/google/common/primitives/Longs.java
index a7d0280a8c4a..6cd69b0fc8cc 100644
--- a/guava/src/com/google/common/primitives/Longs.java
+++ b/guava/src/com/google/common/primitives/Longs.java
@@ -42,6 +42,7 @@
 import org.checkerframework.checker.index.qual.SubstringIndexFor;
 import org.checkerframework.checker.index.qual.HasSubsequence;
 import org.checkerframework.checker.index.qual.LessThan;
+import org.checkerframework.checker.signedness.qual.Signed;
 import org.checkerframework.checker.nullness.qual.Nullable;
 import org.checkerframework.common.value.qual.IntRange;
 import org.checkerframework.common.value.qual.MinLen;
@@ -87,6 +88,7 @@ private Longs() {}
    * @param value a primitive {@code long} value
    * @return a hash code for the value
    */
+  @SuppressWarnings("signedness:shift.unsigned")  // value must be positive?
   public static int hashCode(long value) {
     return (int) (value ^ (value >>> 32));
   }
@@ -155,7 +157,6 @@ public static boolean contains(long[] array, long target) {
    * @param array the array to search for the sequence {@code target}
    * @param target the array to search for as a sub-sequence of {@code array}
    */
-  @SuppressWarnings("substringindex:return.type.incompatible") // https://github.com/kelloggm/checker-framework/issues/206 https://github.com/kelloggm/checker-framework/issues/207 https://github.com/kelloggm/checker-framework/issues/208
   public static @LTEqLengthOf("#1") @SubstringIndexFor(value = "#1", offset="#2.length - 1") int indexOf(long[] array, long[] target) {
     checkNotNull(array, "array");
     checkNotNull(target, "target");
@@ -267,7 +268,6 @@ public static long constrainToRange(long value, long min, long max) {
    * pos is increased the same way as length, so pos points to a valid
    * range of length array.length in result.
    */
-  @SuppressWarnings("upperbound:argument.type.incompatible") // sum of lengths
   public static long[] concat(long[]... arrays) {
     int length = 0;
     for (long[] array : arrays) {
@@ -351,30 +351,17 @@ private AsciiDigits() {}
       @IntRange(from = -1, to = 36) byte [] result = new byte[128];
       Arrays.fill(result, (byte) -1);
       for (int i = 0; i < 10; i++) {
-        @SuppressWarnings({
-          "unused",
-          "lessthan:cast.unsafe", // https://github.com/kelloggm/checker-framework/issues/222
-        })
         byte _unused3 = result['0' + i] = (byte) i;
       }
       for (int i = 0; i < 26; i++) {
-        @SuppressWarnings({
-          "unused",
-          "upperbound:array.access.unsafe.high.range", // https://github.com/typetools/checker-framework/issues/1669
-          "assignment.type.incompatible" // https://github.com/typetools/checker-framework/issues/1669
-        })
+        @SuppressWarnings("value:assignment") // 10 + i will be <= 36
         byte _unused1 = result['A' + i] = (byte) (10 + i);
-        @SuppressWarnings({
-          "unused",
-          "upperbound:array.access.unsafe.high", // https://github.com/typetools/checker-framework/issues/1669
-          "assignment.type.incompatible" // https://github.com/typetools/checker-framework/issues/1669
-        })
+        @SuppressWarnings("value:assignment") // 10 + i will be <= 36
         byte _unused2 = result['a' + i] = (byte) (10 + i);
       }
       asciiDigits = result;
     }
 
-    @SuppressWarnings("lowerbound:array.access.unsafe.low") // https://github.com/kelloggm/checker-framework/issues/192 char should be @NonNegative
     static @IntRange(from = -1, to = 36) int digit(char c) {
       return (c < 128) ? asciiDigits[c] : -1;
     }
@@ -423,7 +410,6 @@ private AsciiDigits() {}
    * @since 19.0
    */
   @Beta
-  @SuppressWarnings("upperbound") // annotation inferred by contract doesn't propagate through checkNotNull
   public static @Nullable Long tryParse(String string, @IntRange(from=2, to=36) int radix) {
     if (checkNotNull(string).isEmpty()) {
       return null;
@@ -733,14 +719,14 @@ public Spliterator.OfLong spliterator() {
     }
 
     @Override
+    @SuppressWarnings("signedness:argument") // target is signed Long
     public boolean contains(Object target) {
       // Overridden to prevent a ton of boxing
       return (target instanceof Long) && Longs.indexOf(array, (Long) target, start, end) != -1;
     }
 
     @Override
-    @SuppressWarnings(
-            "lowerbound:return.type.incompatible") // needs https://github.com/kelloggm/checker-framework/issues/227 on static indexOf method
+    @SuppressWarnings("signedness:argument") // target is signed Long
     public @IndexOrLow("this") int indexOf(Object target) {
       // Overridden to prevent a ton of boxing
       if (target instanceof Long) {
@@ -753,8 +739,7 @@ public boolean contains(Object target) {
     }
 
     @Override
-    @SuppressWarnings(
-            "lowerbound:return.type.incompatible") // needs https://github.com/kelloggm/checker-framework/issues/227 on static indexOf method
+    @SuppressWarnings("signedness:argument") // target is signed Long
     public @IndexOrLow("this") int lastIndexOf(Object target) {
       // Overridden to prevent a ton of boxing
       if (target instanceof Long) {
diff --git a/guava/src/com/google/common/primitives/UnsignedInteger.java b/guava/src/com/google/common/primitives/UnsignedInteger.java
index 1c7011c6c1d2..4cd3068c0b95 100644
--- a/guava/src/com/google/common/primitives/UnsignedInteger.java
+++ b/guava/src/com/google/common/primitives/UnsignedInteger.java
@@ -180,14 +180,16 @@ public UnsignedInteger mod(UnsignedInteger val) {
    * will be equal to {@code this - 2^32}.
    */
   @Override
+  @SuppressWarnings("cast.unsafe")
   public @PolyValue int intValue(@PolyValue UnsignedInteger this) {
-    return value;
+    return (@PolyValue int) value;
   }
 
   /** Returns the value of this {@code UnsignedInteger} as a {@code long}. */
   @Override
+  @SuppressWarnings("cast.unsafe")
   public @NonNegative @PolyValue long longValue(@PolyValue UnsignedInteger this) {
-    return toLong(value);
+    return (@PolyValue long) toLong(value);
   }
 
   /**
@@ -195,6 +197,7 @@ public UnsignedInteger mod(UnsignedInteger val) {
    * primitive conversion from {@code int} to {@code float}, and correctly rounded.
    */
   @Override
+  @SuppressWarnings("cast.unsafe")
   public @PolyValue float floatValue(@PolyValue UnsignedInteger this) {
     return longValue();
   }
diff --git a/guava/src/com/google/common/primitives/UnsignedLong.java b/guava/src/com/google/common/primitives/UnsignedLong.java
index e3efd8406dc0..07d8280fb3cd 100644
--- a/guava/src/com/google/common/primitives/UnsignedLong.java
+++ b/guava/src/com/google/common/primitives/UnsignedLong.java
@@ -23,7 +23,10 @@
 import java.math.BigInteger;
 import org.checkerframework.checker.index.qual.NonNegative;
 import org.checkerframework.checker.nullness.qual.Nullable;
+import org.checkerframework.checker.signedness.qual.Signed;
+import org.checkerframework.checker.signedness.qual.Unsigned;
 import org.checkerframework.common.value.qual.IntRange;
+import org.checkerframework.common.value.qual.PolyValue;
 
 /**
  * A wrapper class for unsigned {@code long} values, supporting arithmetic operations.
@@ -48,9 +51,9 @@ public final class UnsignedLong extends Number implements Comparable<UnsignedLon
   public static final UnsignedLong ONE = new UnsignedLong(1);
   public static final UnsignedLong MAX_VALUE = new UnsignedLong(-1L);
 
-  private final long value;
+  private final @Unsigned long value;
 
-  private UnsignedLong(long value) {
+  private UnsignedLong(@Unsigned long value) {
     this.value = value;
   }
 
@@ -67,7 +70,7 @@ private UnsignedLong(long value) {
    *
    * @since 14.0
    */
-  public static UnsignedLong fromLongBits(long bits) {
+  public static UnsignedLong fromLongBits(@Unsigned long bits) {
     // TODO(lowasser): consider caching small values, like Long.valueOf
     return new UnsignedLong(bits);
   }
@@ -91,13 +94,14 @@ public static UnsignedLong valueOf(@NonNegative long value) {
    * @throws IllegalArgumentException if {@code value} is negative or {@code value >= 2^64}
    */
   @CanIgnoreReturnValue
+  @SuppressWarnings("signedness:cast.unsafe")
   public static UnsignedLong valueOf(BigInteger value) {
     checkNotNull(value);
     checkArgument(
         value.signum() >= 0 && value.bitLength() <= Long.SIZE,
         "value (%s) is outside the range for an unsigned long value",
         value);
-    return fromLongBits(value.longValue());
+    return fromLongBits((@Unsigned long)value.longValue());
   }
 
   /**
@@ -175,7 +179,8 @@ public UnsignedLong mod(UnsignedLong val) {
 
   /** Returns the value of this {@code UnsignedLong} as an {@code int}. */
   @Override
-  public int intValue() {
+  @SuppressWarnings("return")
+  public @PolyValue int intValue(@PolyValue UnsignedLong this) {
     return (int) value;
   }
 
@@ -187,7 +192,8 @@ public int intValue() {
    * will be equal to {@code this - 2^64}.
    */
   @Override
-  public long longValue() {
+  @SuppressWarnings("return")
+  public @PolyValue long longValue(@PolyValue UnsignedLong this) {
     return value;
   }
 
@@ -196,8 +202,11 @@ public long longValue() {
    * primitive conversion from {@code long} to {@code float}, and correctly rounded.
    */
   @Override
-  public float floatValue() {
-    @SuppressWarnings("cast")
+  @SuppressWarnings({
+    "signedness:comparison", // unsigned compare
+    "value:return" // forDigit
+  })
+  public @PolyValue float floatValue(@PolyValue UnsignedLong this) {
     float fValue = (float) (value & UNSIGNED_MASK);
     if (value < 0) {
       fValue += 0x1.0p63f;
@@ -210,8 +219,11 @@ public float floatValue() {
    * primitive conversion from {@code long} to {@code double}, and correctly rounded.
    */
   @Override
-  public double doubleValue() {
-    @SuppressWarnings("cast")
+  @SuppressWarnings({
+    "signedness:comparison", // unsigned compare
+    "value:return" // forDigit
+  })
+  public @PolyValue double doubleValue(@PolyValue UnsignedLong this) {
     double dValue = (double) (value & UNSIGNED_MASK);
     if (value < 0) {
       dValue += 0x1.0p63;
@@ -220,6 +232,7 @@ public double doubleValue() {
   }
 
   /** Returns the value of this {@code UnsignedLong} as a {@link BigInteger}. */
+  @SuppressWarnings("signedness:comparison.unsignedlhs")
   public BigInteger bigIntegerValue() {
     BigInteger bigInt = BigInteger.valueOf(value & UNSIGNED_MASK);
     if (value < 0) {
@@ -235,6 +248,7 @@ public int compareTo(UnsignedLong o) {
   }
 
   @Override
+  @SuppressWarnings("signedness:argument")
   public int hashCode() {
     return Longs.hashCode(value);
   }
diff --git a/guava/src/com/google/common/primitives/UnsignedLongs.java b/guava/src/com/google/common/primitives/UnsignedLongs.java
index 73f7260f71ee..18c2da4fb41d 100644
--- a/guava/src/com/google/common/primitives/UnsignedLongs.java
+++ b/guava/src/com/google/common/primitives/UnsignedLongs.java
@@ -65,6 +65,7 @@ private UnsignedLongs() {}
    * longs, that is, {@code a <= b} as unsigned longs if and only if {@code flip(a) <= flip(b)} as
    * signed longs.
    */
+  @SuppressWarnings("signedness:return")
   private static @PolySigned long flip(@PolySigned long a) {
     return a ^ Long.MIN_VALUE;
   }
@@ -80,6 +81,7 @@ private UnsignedLongs() {}
    * @return a negative value if {@code a} is less than {@code b}; a positive value if {@code a} is
    *     greater than {@code b}; or zero if they are equal
    */
+  @SuppressWarnings("signedness:argument")
   public static int compare(@Unsigned long a, @Unsigned long b) {
     return Longs.compare(flip(a), flip(b));
   }
@@ -92,6 +94,7 @@ public static int compare(@Unsigned long a, @Unsigned long b) {
    *     the array according to {@link #compare}
    * @throws IllegalArgumentException if {@code array} is empty
    */
+  @SuppressWarnings("signedness:comparison")
   public static @Unsigned long min(@Unsigned long @MinLen(1)... array) {
     checkArgument(array.length > 0);
     long min = flip(array[0]);
@@ -112,6 +115,7 @@ public static int compare(@Unsigned long a, @Unsigned long b) {
    *     in the array according to {@link #compare}
    * @throws IllegalArgumentException if {@code array} is empty
    */
+  @SuppressWarnings("signedness:comparison")
   public static @Unsigned long max(@Unsigned long @MinLen(1)... array) {
     checkArgument(array.length > 0);
     long max = flip(array[0]);
@@ -198,6 +202,7 @@ public static void sort(@Unsigned long[] array) {
    *
    * @since 23.1
    */
+  @SuppressWarnings("signedness:argument")
   public static void sort(@Unsigned long[] array, @IndexOrHigh("#1") int fromIndex, @IndexOrHigh("#1") int toIndex) {
     checkNotNull(array);
     checkPositionIndexes(fromIndex, toIndex, array.length);
@@ -227,6 +232,7 @@ public static void sortDescending(@Unsigned long[] array) {
    *
    * @since 23.1
    */
+  @SuppressWarnings("signedness:argument")
   public static void sortDescending(@Unsigned long[] array, @IndexOrHigh("#1") int fromIndex, @IndexOrHigh("#1") int toIndex) {
     checkNotNull(array);
     checkPositionIndexes(fromIndex, toIndex, array.length);
@@ -249,6 +255,7 @@ public static void sortDescending(@Unsigned long[] array, @IndexOrHigh("#1") int
    * @param divisor the divisor (denominator)
    * @throws ArithmeticException if divisor is 0
    */
+  @SuppressWarnings("signedness:comparison")
   public static @Unsigned long divide(@Unsigned long dividend, @Unsigned long divisor) {
     if (divisor < 0) { // i.e., divisor >= 2^63:
       if (compare(dividend, divisor) < 0) {
@@ -269,6 +276,7 @@ public static void sortDescending(@Unsigned long[] array, @IndexOrHigh("#1") int
      * floor(floor(x)/i) == floor(x/i) for any real x and integer i != 0. The proof is not quite
      * trivial.
      */
+    @SuppressWarnings("signedness:operation")
     long quotient = ((dividend >>> 1) / divisor) << 1;
     long rem = dividend - quotient * divisor;
     return quotient + (compare(rem, divisor) >= 0 ? 1 : 0);
@@ -285,6 +293,7 @@ public static void sortDescending(@Unsigned long[] array, @IndexOrHigh("#1") int
    * @throws ArithmeticException if divisor is 0
    * @since 11.0
    */
+  @SuppressWarnings("signedness:comparison")
   public static @Unsigned long remainder(@Unsigned long dividend, @Unsigned long divisor) {
     if (divisor < 0) { // i.e., divisor >= 2^63:
       if (compare(dividend, divisor) < 0) {
@@ -305,6 +314,7 @@ public static void sortDescending(@Unsigned long[] array, @IndexOrHigh("#1") int
      * that floor(floor(x)/i) == floor(x/i) for any real x and integer i != 0. The proof is not
      * quite trivial.
      */
+    @SuppressWarnings("signedness:operation")
     long quotient = ((dividend >>> 1) / divisor) << 1;
     long rem = dividend - quotient * divisor;
     return rem - (compare(rem, divisor) >= 0 ? divisor : 0);
@@ -464,9 +474,9 @@ public static String toString(@Unsigned long x) {
    * Assuming that Character.MIN_RADIX == 2
    */
   @SuppressWarnings({
-    "lowerbound:argument.type.incompatible", // https://github.com/kelloggm/checker-framework/issues/193
-    "lowerbound:unary.decrement.type.incompatible",
-    "lowerbound:array.access.unsafe.low", "lowerbound:compound.assignment.type.incompatible" // ulong converted to string is at most 64 chars
+    "signedness:comparison", // unsigned compare
+    "signedness:operation", // unsigned divide
+    "signedness:argument" // forDigit
   })
   public static String toString(@Unsigned long x, @IntRange(from = Character.MIN_RADIX,to = Character.MAX_RADIX) int radix) {
     checkArgument(
diff --git a/guava/src/com/google/common/util/concurrent/AtomicDouble.java b/guava/src/com/google/common/util/concurrent/AtomicDouble.java
index 8f881dddff78..e57bdc7b95f4 100644
--- a/guava/src/com/google/common/util/concurrent/AtomicDouble.java
+++ b/guava/src/com/google/common/util/concurrent/AtomicDouble.java
@@ -22,6 +22,8 @@
 import com.google.j2objc.annotations.ReflectionSupport;
 import java.util.concurrent.atomic.AtomicLongFieldUpdater;
 
+import org.checkerframework.common.value.qual.PolyValue;
+
 /**
  * A {@code double} value that may be updated atomically. See the {@link
  * java.util.concurrent.atomic} package specification for description of the properties of atomic
@@ -199,8 +201,9 @@ public String toString() {
    * conversion.
    */
   @Override
-  public int intValue() {
-    return (int) get();
+  @SuppressWarnings("cast.unsafe")
+  public @PolyValue int intValue(@PolyValue AtomicDouble this) {
+    return (@PolyValue int) get();
   }
 
   /**
@@ -208,8 +211,9 @@ public int intValue() {
    * conversion.
    */
   @Override
-  public long longValue() {
-    return (long) get();
+  @SuppressWarnings("cast.unsafe")
+  public @PolyValue long longValue(@PolyValue AtomicDouble this) {
+    return (@PolyValue long) get();
   }
 
   /**
@@ -217,14 +221,16 @@ public long longValue() {
    * conversion.
    */
   @Override
-  public float floatValue() {
-    return (float) get();
+  @SuppressWarnings("cast.unsafe")
+  public @PolyValue float floatValue(@PolyValue AtomicDouble this) {
+    return (@PolyValue float) get();
   }
 
   /** Returns the value of this {@code AtomicDouble} as a {@code double}. */
   @Override
-  public double doubleValue() {
-    return get();
+  @SuppressWarnings("cast.unsafe")
+  public @PolyValue double doubleValue(@PolyValue AtomicDouble this) {
+    return (@PolyValue double) get();
   }
 
   /**
diff --git a/guava/src/com/google/common/util/concurrent/ClosingFuture.java b/guava/src/com/google/common/util/concurrent/ClosingFuture.java
index 09767dc00fd4..f2a315875395 100644
--- a/guava/src/com/google/common/util/concurrent/ClosingFuture.java
+++ b/guava/src/com/google/common/util/concurrent/ClosingFuture.java
@@ -341,8 +341,7 @@ public static final class ValueAndCloser<V> {
      * @throws CancellationException if the computation was cancelled
      * @throws ExecutionException if the computation threw an exception
      */
-    @Nullable
-    public V get() throws ExecutionException {
+    public @Nullable V get() throws ExecutionException {
       return getDone(closingFuture.future);
     }
 
diff --git a/pom.xml b/pom.xml
index eb05a1aa331f..13c549ef092d 100644
--- a/pom.xml
+++ b/pom.xml
@@ -274,7 +274,7 @@
       <dependency>
         <groupId>org.checkerframework</groupId>
         <artifactId>checker-qual</artifactId>
-        <version>3.19.0</version>
+        <version>3.30.0</version>
       </dependency>
       <dependency>
         <groupId>com.google.errorprone</groupId>

From 833a94056826ef06a3064ee02d09703316551757 Mon Sep 17 00:00:00 2001
From: Mark Roberts <markro@cs.washington.edu>
Date: Wed, 15 Feb 2023 16:09:38 -0800
Subject: [PATCH 05/21] turn on signedness checking

---
 azure-pipelines.yml                                       | 2 ++
 guava/src/com/google/common/math/LongMath.java            | 7 +++++++
 guava/src/com/google/common/primitives/UnsignedLongs.java | 5 ++++-
 typecheck.sh                                              | 2 ++
 4 files changed, 15 insertions(+), 1 deletion(-)

diff --git a/azure-pipelines.yml b/azure-pipelines.yml
index 68c2e35c9e04..86223ead9a35 100644
--- a/azure-pipelines.yml
+++ b/azure-pipelines.yml
@@ -30,6 +30,8 @@ jobs:
         typechecker: regex
       signatureJob:
         typechecker: signature
+      signednessJob:
+        typechecker: signedness
     maxParallel: 10
   steps:
   - checkout: self
diff --git a/guava/src/com/google/common/math/LongMath.java b/guava/src/com/google/common/math/LongMath.java
index d80056ce6af0..367d80f70111 100644
--- a/guava/src/com/google/common/math/LongMath.java
+++ b/guava/src/com/google/common/math/LongMath.java
@@ -1054,6 +1054,7 @@ public static boolean isPrime(long n) {
       return true;
     }
 
+    //@SuppressWarnings("signedness:comparison") // n is guaranteed to be positive
     for (@Unsigned long[] baseSet : millerRabinBaseSets) {
       if (n <= baseSet[0]) {
         for (int i = 1; i < baseSet.length; i++) {
@@ -1103,6 +1104,7 @@ private enum MillerRabinTester {
     /** Works for inputs ≤ FLOOR_SQRT_MAX_LONG. */
     SMALL {
       @Override
+      @SuppressWarnings("signedness:operation")
       @Unsigned long mulMod(@Unsigned long a, @Unsigned long b, @Unsigned long m) {
         /*
          * lowasser, 2015-Feb-12: Benchmarks suggest that changing this to UnsignedLongs.remainder
@@ -1114,6 +1116,7 @@ private enum MillerRabinTester {
       }
 
       @Override
+      @SuppressWarnings("signedness:operation")
       @Unsigned long squareMod(@Unsigned long a, @Unsigned long m) {
         return (a * a) % m;
       }
@@ -1121,6 +1124,7 @@ private enum MillerRabinTester {
     /** Works for all nonnegative signed longs. */
     LARGE {
       /** Returns (a + b) mod m. Precondition: {@code 0 <= a}, {@code b < m < 2^63}. */
+      @SuppressWarnings("signedness:comparison")
       private @Unsigned long plusMod(@Unsigned long a, @Unsigned long b, @Unsigned long m) {
         return (a >= m - b) ? (a + b - m) : (a + b);
       }
@@ -1139,6 +1143,7 @@ private enum MillerRabinTester {
       }
 
       @Override
+      @SuppressWarnings("signedness:comparison")
       @Unsigned long mulMod(@Unsigned long a, @Unsigned long b, @Unsigned long m) {
         long aHi = a >>> 32; // < 2^31
         long bHi = b >>> 32; // < 2^31
@@ -1165,6 +1170,7 @@ private enum MillerRabinTester {
       }
 
       @Override
+      @SuppressWarnings("signedness:comparison")
       @Unsigned long squareMod(@Unsigned long a, @Unsigned long m) {
         long aHi = a >>> 32; // < 2^31
         long aLo = a & 0xFFFFFFFFL; // < 2^32
@@ -1188,6 +1194,7 @@ private enum MillerRabinTester {
       }
     };
 
+    @SuppressWarnings("signedness:comparison")
     static boolean test(@Unsigned long base, @Unsigned long n) {
       // Since base will be considered % n, it's okay if base > FLOOR_SQRT_MAX_LONG,
       // so long as n <= FLOOR_SQRT_MAX_LONG.
diff --git a/guava/src/com/google/common/primitives/UnsignedLongs.java b/guava/src/com/google/common/primitives/UnsignedLongs.java
index 18c2da4fb41d..1542a4b8eade 100644
--- a/guava/src/com/google/common/primitives/UnsignedLongs.java
+++ b/guava/src/com/google/common/primitives/UnsignedLongs.java
@@ -27,8 +27,10 @@
 import org.checkerframework.checker.index.qual.IndexOrHigh;
 import org.checkerframework.common.value.qual.IntRange;
 import org.checkerframework.common.value.qual.MinLen;
-import org.checkerframework.checker.signedness.qual.Unsigned;
+import org.checkerframework.checker.signedness.qual.Signed;
 import org.checkerframework.checker.signedness.qual.PolySigned;
+import org.checkerframework.checker.signedness.qual.Unsigned;
+import org.checkerframework.framework.qual.AnnotatedFor;
 
 /**
  * Static utility methods pertaining to {@code long} primitives that interpret values as
@@ -53,6 +55,7 @@
  * @author Colin Evans
  * @since 10.0
  */
+@AnnotatedFor({"signedness"})
 @Beta
 @GwtCompatible
 public final class UnsignedLongs {
diff --git a/typecheck.sh b/typecheck.sh
index a30b7ecb91b9..c41441aecd5b 100755
--- a/typecheck.sh
+++ b/typecheck.sh
@@ -40,6 +40,8 @@ elif [[ "$1" == "regex" ]]; then
   (cd guava && mvn -B compile -P checkerframework-local -Dcheckerframework.checkers=org.checkerframework.checker.regex.RegexChecker)
 elif [[ "$1" == "signature" ]]; then
   (cd guava && mvn -B compile -P checkerframework-local -Dcheckerframework.checkers=org.checkerframework.checker.signature.SignatureChecker)
+elif [[ "$1" == "signedness" ]]; then
+  (cd guava && mvn -B compile -P checkerframework-local -Dcheckerframework.checkers=org.checkerframework.checker.signedness.SignednessChecker)
 elif [[ "$1" == "nothing" ]]; then
   true
 else

From 410394a72489163046f2f90318eb9b84a439cc70 Mon Sep 17 00:00:00 2001
From: Mark Roberts <markro49@users.noreply.github.com>
Date: Wed, 12 Apr 2023 10:23:57 -0700
Subject: [PATCH 06/21] Merge v31.1 source from google/guava

---
 .github/dependabot.yml                        |   16 +
 .github/workflows/ci.yml                      |   30 +-
 README-typetools.md                           |   23 +-
 README.md                                     |   39 +-
 android/guava-bom/pom.xml                     |    2 +-
 android/guava-testlib/pom.xml                 |    6 +-
 .../testing/AbstractContainerTester.java      |    4 +-
 .../collect/testing/AbstractMapTester.java    |    8 +-
 .../testing/CollectionTestSuiteBuilder.java   |    2 +
 .../testing/DerivedCollectionGenerators.java  |   13 +-
 .../FeatureSpecificTestSuiteBuilder.java      |   20 +-
 .../common/collect/testing/Helpers.java       |   18 +-
 .../collect/testing/ListTestSuiteBuilder.java |    2 +
 .../collect/testing/MapInterfaceTest.java     |  212 +--
 .../collect/testing/MapTestSuiteBuilder.java  |    8 +
 .../collect/testing/MinimalCollection.java    |    4 +-
 .../collect/testing/MinimalIterable.java      |    4 +-
 .../common/collect/testing/MinimalSet.java    |    4 +-
 .../testing/NavigableMapTestSuiteBuilder.java |    4 +-
 .../testing/NavigableSetTestSuiteBuilder.java |    9 +-
 .../collect/testing/OneSizeGenerator.java     |    2 +-
 .../ReserializingTestCollectionGenerator.java |    2 +-
 .../ReserializingTestSetGenerator.java        |    2 +-
 .../common/collect/testing/SafeTreeSet.java   |    8 +-
 .../collect/testing/SetTestSuiteBuilder.java  |    2 +
 .../testing/SortedMapInterfaceTest.java       |    6 +-
 .../testing/SortedMapTestSuiteBuilder.java    |   10 +-
 .../testing/SortedSetTestSuiteBuilder.java    |   13 +-
 .../collect/testing/features/FeatureUtil.java |    8 +-
 .../google/AbstractMultimapTester.java        |   10 +-
 .../testing/google/BiMapTestSuiteBuilder.java |    6 +
 .../DerivedGoogleCollectionGenerators.java    |    6 +-
 .../collect/testing/google/MapGenerators.java |   12 +-
 .../google/MultimapTestSuiteBuilder.java      |   12 +
 .../google/MultisetNavigationTester.java      |    2 +-
 .../google/MultisetTestSuiteBuilder.java      |    6 +
 .../google/SetMultimapAsMapTester.java        |    2 +-
 .../SortedMultisetTestSuiteBuilder.java       |   18 +-
 .../google/SortedSetMultimapAsMapTester.java  |    2 +-
 .../google/UnmodifiableCollectionTests.java   |    4 +-
 .../testers/CollectionIteratorTester.java     |    6 +-
 .../testers/CollectionToArrayTester.java      |    4 +-
 .../testers/NavigableSetNavigationTester.java |    2 +-
 .../common/escape/testing/EscaperAsserts.java |    2 -
 .../testing/AbstractPackageSanityTests.java   |   20 +-
 .../common/testing/ArbitraryInstances.java    |   12 +-
 .../common/testing/ClassSanityTester.java     |   10 +-
 .../google/common/testing/EqualsTester.java   |    4 +-
 .../common/testing/EquivalenceTester.java     |    7 +-
 .../com/google/common/testing/FakeTicker.java |    2 -
 .../testing/ForwardingWrapperTester.java      |    6 +-
 .../common/testing/FreshValueGenerator.java   |  243 ++--
 .../google/common/testing/GcFinalization.java |   35 +-
 .../common/testing/NullPointerTester.java     |   17 +-
 .../common/testing/RelationshipTester.java    |    2 +-
 .../common/testing/SerializableTester.java    |    3 -
 .../google/common/testing/TestLogHandler.java |    6 +-
 .../testing/AbstractListenableFutureTest.java |  109 +-
 .../testing/MockFutureListener.java           |    8 +-
 .../SameThreadScheduledExecutorService.java   |    4 +-
 .../concurrent/testing/TestingExecutors.java  |    6 +-
 .../FeatureSpecificTestSuiteBuilderTest.java  |    6 +-
 .../testing/MapTestSuiteBuilderTests.java     |   92 ++
 .../common/testing/ClassSanityTesterTest.java |   36 +-
 .../common/testing/EquivalenceTesterTest.java |    2 +-
 .../common/testing/NullPointerTesterTest.java |   78 +-
 .../common/base/StringsRepeatBenchmark.java   |    6 +-
 .../common/base/ToStringHelperBenchmark.java  |    2 +
 .../ConcurrentHashMultisetBenchmark.java      |   12 +-
 .../google/common/collect/MapBenchmark.java   |    2 +-
 .../concurrent/ExecutionListBenchmark.java    |    8 +-
 .../FuturesGetCheckedBenchmark.java           |    7 +-
 .../MonitorBasedArrayBlockingQueue.java       |   72 +-
 .../MonitorBasedPriorityBlockingQueue.java    |   68 +-
 android/guava-tests/pom.xml                   |    9 +-
 .../common/base/AbstractIteratorTest.java     |    2 +-
 .../com/google/common/base/AsciiTest.java     |   13 +-
 .../google/common/base/CharMatcherTest.java   |    2 +-
 .../com/google/common/base/OptionalTest.java  |    6 +
 .../google/common/base/PreconditionsTest.java |   19 +-
 .../common/base/ToStringHelperTest.java       |   38 +-
 .../com/google/common/base/VerifyTest.java    |    8 +-
 .../common/cache/CacheBuilderFactory.java     |    4 +-
 .../com/google/common/cache/CacheTesting.java |    4 +-
 .../google/common/cache/LocalCacheTest.java   |    2 +-
 .../common/cache/TestingCacheLoaders.java     |    4 +-
 .../common/collect/AbstractIteratorTest.java  |    1 +
 .../common/collect/AbstractMapEntryTest.java  |    3 +-
 .../common/collect/DiscreteDomainTest.java    |   44 +
 .../common/collect/FluentIterableTest.java    |    4 +-
 .../common/collect/ForwardingMapTest.java     |    2 +-
 .../collect/ForwardingSortedMultisetTest.java |   10 +-
 .../common/collect/ImmutableBiMapTest.java    |  173 ++-
 .../collect/ImmutableListMultimapTest.java    |   10 +
 .../common/collect/ImmutableMapTest.java      |  412 +++++-
 .../common/collect/ImmutableMultimapTest.java |   11 +
 .../common/collect/ImmutableRangeSetTest.java |    4 +
 .../collect/ImmutableSetMultimapTest.java     |   10 +
 .../collect/ImmutableSortedMapTest.java       |  140 +-
 .../collect/ImmutableSortedSetTest.java       |    2 +-
 .../google/common/collect/IteratorsTest.java  |    4 +
 .../collect/LinkedListMultimapTest.java       |   10 +
 .../com/google/common/collect/ListsTest.java  |   16 +-
 .../google/common/collect/MapMakerTest.java   |   41 +-
 .../common/collect/MapsCollectionTest.java    |    6 +-
 .../com/google/common/collect/MapsTest.java   |   10 +-
 .../collect/MapsTransformValuesTest.java      |    6 +-
 ...ansformValuesUnmodifiableIteratorTest.java |    6 +-
 .../google/common/collect/MultimapsTest.java  |   13 +-
 .../google/common/collect/OrderingTest.java   |    4 +-
 .../com/google/common/collect/RangeTest.java  |   10 +
 .../collect/RegularImmutableAsListTest.java   |    3 +-
 .../common/collect/SetOperationsTest.java     |  166 ++-
 .../com/google/common/collect/SetsTest.java   |    5 +-
 .../collect/SimpleAbstractMultisetTest.java   |    6 +-
 .../common/collect/SynchronizedDequeTest.java |    5 +-
 .../common/collect/SynchronizedMapTest.java   |   10 +-
 .../collect/SynchronizedMultimapTest.java     |   20 +-
 .../common/collect/SynchronizedQueueTest.java |    5 +-
 .../common/collect/SynchronizedSetTest.java   |   10 +-
 .../common/collect/SynchronizedTableTest.java |    6 +-
 .../common/collect/TopKSelectorTest.java      |   11 +
 .../collect/UnmodifiableIteratorTest.java     |    1 +
 .../collect/UnmodifiableListIteratorTest.java |    3 +
 .../google/common/escape/EscapersTest.java    |    2 +-
 .../common/eventbus/PackageSanityTests.java   |    4 +-
 .../google/common/eventbus/StringCatcher.java |    6 +-
 .../outside/AbstractEventBusTest.java         |   55 +
 .../AbstractNotAnnotatedInSuperclassTest.java |   61 +
 .../AnnotatedAndAbstractInSuperclassTest.java |   63 +
 .../AnnotatedNotAbstractInSuperclassTest.java |  116 ++
 .../AnnotatedSubscriberFinderTests.java       |  448 -------
 .../outside/BaseSubscriberFinderTest.java     |   53 +
 .../eventbus/outside/DeepInterfaceTest.java   |  153 +++
 ...rAbstractNorAnnotatedInSuperclassTest.java |   74 ++
 .../com/google/common/graph/MapCacheTest.java |   21 -
 .../google/common/hash/BloomFilterTest.java   |    9 +-
 .../common/hash/Fingerprint2011Test.java      |  233 ++++
 .../google/common/hash/HashFunctionEnum.java  |    1 +
 .../com/google/common/hash/HashTestUtils.java |    4 +-
 .../com/google/common/hash/HashingTest.java   |   19 +-
 .../google/common/hash/Murmur3Hash32Test.java |   79 +-
 .../google/common/io/BaseEncodingTest.java    |   14 +-
 .../com/google/common/io/ByteSourceTest.java  |    3 +-
 .../google/common/io/ByteSourceTester.java    |    2 +-
 .../com/google/common/io/ByteStreamsTest.java |   41 +-
 .../common/io/CharSequenceReaderTest.java     |    6 +-
 .../com/google/common/io/CharSourceTest.java  |    3 +-
 .../test/com/google/common/io/CloserTest.java |   10 +-
 .../io/LittleEndianDataInputStreamTest.java   |    1 +
 .../common/io/PatternFilenameFilterTest.java  |   13 +
 .../google/common/io/SourceSinkFactories.java |   10 +-
 .../google/common/io/SourceSinkTester.java    |    2 +-
 .../com/google/common/math/IntMathTest.java   |    7 +-
 .../common/math/MathPreconditionsTest.java    |   11 +
 .../common/math/QuantilesAlgorithm.java       |    4 +-
 .../com/google/common/math/QuantilesTest.java |   10 +-
 .../google/common/net/HostAndPortTest.java    |    7 +
 .../google/common/net/HostSpecifierTest.java  |    5 +-
 .../google/common/net/HttpHeadersTest.java    |    4 +-
 .../google/common/net/InetAddressesTest.java  |   28 +
 .../common/net/InternetDomainNameTest.java    |    4 +-
 .../com/google/common/net/MediaTypeTest.java  |    3 +-
 .../google/common/net/PercentEscaperTest.java |   13 +-
 .../common/primitives/BooleansTest.java       |    3 +-
 .../common/primitives/UnsignedLongTest.java   |   25 +-
 .../google/common/reflect/ElementTest.java    |  247 ----
 .../google/common/reflect/InvokableTest.java  |  199 ++-
 .../google/common/reflect/TypeTokenTest.java  |   16 +-
 .../AbstractAbstractFutureTest.java           |    1 -
 ...st.java => AbstractClosingFutureTest.java} |  193 +--
 .../AbstractExecutionThreadServiceTest.java   |    9 -
 .../concurrent/AbstractFutureBenchmarks.java  |   10 +-
 .../AbstractFutureCancellationCauseTest.java  |    1 +
 .../util/concurrent/AbstractFutureTest.java   |    2 +-
 .../concurrent/AbstractIdleServiceTest.java   |    1 -
 .../AbstractScheduledServiceTest.java         |   90 +-
 .../util/concurrent/AbstractServiceTest.java  |    9 -
 .../concurrent/AtomicDoubleArrayTest.java     |    2 -
 .../util/concurrent/AtomicDoubleTest.java     |    2 -
 .../concurrent/AtomicLongMapBasherTest.java   |   34 +-
 .../util/concurrent/AtomicLongMapTest.java    |    6 +-
 .../ClosingFutureFinishToFutureTest.java      |   94 ++
 ...osingFutureFinishToValueAndCloserTest.java |  148 +++
 .../CycleDetectingLockFactoryTest.java        |    3 -
 .../util/concurrent/ExecutionListTest.java    |    3 -
 .../concurrent/ExecutionSequencerTest.java    |    3 -
 .../util/concurrent/FluentFutureTest.java     |    1 -
 .../concurrent/ForwardingObjectTester.java    |    2 +-
 .../util/concurrent/FutureCallbackTest.java   |    6 +-
 .../concurrent/FuturesGetCheckedTest.java     |    5 +-
 .../common/util/concurrent/FuturesTest.java   |   35 +-
 .../concurrent/FuturesTransformAsyncTest.java |    1 -
 .../util/concurrent/GeneratedMonitorTest.java |    1 -
 .../concurrent/InterruptibleMonitorTest.java  |    1 -
 .../concurrent/InterruptibleTaskTest.java     |   54 +-
 .../util/concurrent/JSR166TestCase.java       |    2 +-
 .../concurrent/JdkFutureAdaptersTest.java     |    3 -
 .../concurrent/ListenableFutureTaskTest.java  |    3 -
 .../concurrent/ListenableFutureTester.java    |    6 +-
 .../concurrent/ListenerCallQueueTest.java     |    2 -
 .../util/concurrent/MonitorTestCase.java      |    1 -
 .../util/concurrent/MoreExecutorsTest.java    |   32 +-
 .../concurrent/SequentialExecutorTest.java    |   10 +-
 .../util/concurrent/ServiceManagerTest.java   |   22 +-
 .../util/concurrent/SettableFutureTest.java   |    4 -
 .../concurrent/SimpleTimeLimiterTest.java     |    1 -
 .../common/util/concurrent/StripedTest.java   |    6 +-
 .../concurrent/SupplementalMonitorTest.java   |    1 -
 .../common/util/concurrent/TestThread.java    |    6 +-
 .../concurrent/ThreadFactoryBuilderTest.java  |   10 -
 .../TrustedListenableFutureTaskTest.java      |    3 -
 .../UncaughtExceptionHandlersTest.java        |    1 -
 .../concurrent/UninterruptibleFutureTest.java |   11 -
 .../UninterruptibleMonitorTest.java           |    1 -
 .../util/concurrent/UninterruptiblesTest.java |    1 -
 android/guava/pom.xml                         |   43 +-
 .../src/com/google/common/base/Absent.java    |    7 +-
 .../google/common/base/AbstractIterator.java  |   16 +-
 .../src/com/google/common/base/Ascii.java     |    5 +-
 .../com/google/common/base/CaseFormat.java    |   10 +-
 .../com/google/common/base/CharMatcher.java   |    5 +-
 .../src/com/google/common/base/Charsets.java  |    1 +
 .../com/google/common/base/CommonMatcher.java |    1 +
 .../com/google/common/base/CommonPattern.java |    1 +
 .../src/com/google/common/base/Converter.java |  160 ++-
 .../src/com/google/common/base/Defaults.java  |   46 +-
 .../base/ElementTypesAreNonnullByDefault.java |   41 +
 .../src/com/google/common/base/Enums.java     |    9 +-
 .../com/google/common/base/Equivalence.java   |   83 +-
 .../base/ExtraObjectsMethodsForWeb.java       |    1 +
 .../base/FinalizablePhantomReference.java     |    4 +-
 .../common/base/FinalizableReference.java     |    1 +
 .../base/FinalizableReferenceQueue.java       |   13 +-
 .../common/base/FinalizableSoftReference.java |    4 +-
 .../common/base/FinalizableWeakReference.java |    4 +-
 .../src/com/google/common/base/Function.java  |   12 +-
 .../common/base/FunctionalEquivalence.java    |   11 +-
 .../src/com/google/common/base/Functions.java |  105 +-
 .../common/base/Java8Compatibility.java       |   44 +
 .../com/google/common/base/Java8Usage.java    |   45 -
 .../com/google/common/base/JdkPattern.java    |    1 +
 .../src/com/google/common/base/Joiner.java    |   82 +-
 .../com/google/common/base/MoreObjects.java   |  115 +-
 .../com/google/common/base/NullnessCasts.java |   60 +
 .../src/com/google/common/base/Objects.java   |    8 +-
 .../src/com/google/common/base/Optional.java  |   10 +-
 .../common/base/PairwiseEquivalence.java      |   16 +-
 .../common/base/ParametricNullness.java       |   52 +
 .../google/common/base/PatternCompiler.java   |    1 +
 .../src/com/google/common/base/Platform.java  |   10 +-
 .../com/google/common/base/Preconditions.java |  374 +++---
 .../src/com/google/common/base/Predicate.java |   10 +-
 .../com/google/common/base/Predicates.java    |  139 +-
 .../src/com/google/common/base/Present.java   |    7 +-
 .../google/common/base/SmallCharMatcher.java  |    1 +
 .../src/com/google/common/base/Splitter.java  |    3 +
 .../common/base/StandardSystemProperty.java   |    5 +-
 .../src/com/google/common/base/Stopwatch.java |    5 +-
 .../src/com/google/common/base/Strings.java   |   17 +-
 .../src/com/google/common/base/Supplier.java  |    5 +-
 .../src/com/google/common/base/Suppliers.java |   89 +-
 .../com/google/common/base/Throwables.java    |   60 +-
 .../src/com/google/common/base/Ticker.java    |    1 +
 .../src/com/google/common/base/Utf8.java      |    1 +
 .../src/com/google/common/base/Verify.java    |  120 +-
 .../google/common/base/VerifyException.java   |    9 +-
 .../common/base/internal/Finalizer.java       |   16 +-
 .../google/common/cache/AbstractCache.java    |   10 +-
 .../common/cache/AbstractLoadingCache.java    |    1 +
 .../src/com/google/common/cache/Cache.java    |   16 +-
 .../com/google/common/cache/CacheBuilder.java |   78 +-
 .../google/common/cache/CacheBuilderSpec.java |   64 +-
 .../com/google/common/cache/CacheLoader.java  |    1 +
 .../com/google/common/cache/CacheStats.java   |    5 +-
 .../ElementTypesAreNonnullByDefault.java      |   41 +
 .../google/common/cache/ForwardingCache.java  |   14 +-
 .../common/cache/ForwardingLoadingCache.java  |    1 +
 .../com/google/common/cache/LoadingCache.java |    3 +
 .../com/google/common/cache/LocalCache.java   |  162 +--
 .../com/google/common/cache/LongAddable.java  |    1 +
 .../com/google/common/cache/LongAddables.java |    4 +-
 .../com/google/common/cache/LongAdder.java    |    1 +
 .../common/cache/ParametricNullness.java      |   52 +
 .../google/common/cache/ReferenceEntry.java   |    8 +-
 .../com/google/common/cache/RemovalCause.java |    1 +
 .../google/common/cache/RemovalListener.java  |    1 +
 .../google/common/cache/RemovalListeners.java |   17 +-
 .../common/cache/RemovalNotification.java     |   13 +-
 .../com/google/common/cache/Striped64.java    |   10 +-
 .../src/com/google/common/cache/Weigher.java  |    1 +
 .../google/common/collect/AbstractBiMap.java  |  102 +-
 .../collect/AbstractIndexedListIterator.java  |    8 +-
 .../common/collect/AbstractIterator.java      |   19 +-
 .../common/collect/AbstractListMultimap.java  |   23 +-
 .../collect/AbstractMapBasedMultimap.java     |  274 ++--
 .../collect/AbstractMapBasedMultiset.java     |   30 +-
 .../common/collect/AbstractMapEntry.java      |   14 +-
 .../common/collect/AbstractMultimap.java      |   35 +-
 .../common/collect/AbstractMultiset.java      |   27 +-
 .../common/collect/AbstractNavigableMap.java  |   56 +-
 .../common/collect/AbstractRangeSet.java      |    6 +-
 .../collect/AbstractSequentialIterator.java   |   19 +-
 .../common/collect/AbstractSetMultimap.java   |   23 +-
 .../AbstractSortedKeySortedSetMultimap.java   |    6 +-
 .../collect/AbstractSortedMultiset.java       |   19 +-
 .../collect/AbstractSortedSetMultimap.java    |   19 +-
 .../google/common/collect/AbstractTable.java  |   39 +-
 .../common/collect/AllEqualOrdering.java      |   15 +-
 .../common/collect/ArrayListMultimap.java     |   16 +-
 .../com/google/common/collect/ArrayTable.java |  168 ++-
 .../common/collect/BaseImmutableMultimap.java |    1 +
 .../src/com/google/common/collect/BiMap.java  |   22 +-
 .../com/google/common/collect/BoundType.java  |    5 +-
 .../common/collect/ByFunctionOrdering.java    |   11 +-
 .../google/common/collect/CartesianList.java  |   13 +-
 .../common/collect/ClassToInstanceMap.java    |   24 +-
 .../common/collect/CollectPreconditions.java  |    1 +
 .../google/common/collect/Collections2.java   |   56 +-
 .../google/common/collect/CompactHashMap.java |  378 ++++--
 .../google/common/collect/CompactHashSet.java |  180 ++-
 .../google/common/collect/CompactHashing.java |   24 +-
 .../common/collect/CompactLinkedHashMap.java  |   61 +-
 .../common/collect/CompactLinkedHashSet.java  |   73 +-
 .../common/collect/ComparatorOrdering.java    |   11 +-
 .../google/common/collect/Comparators.java    |   25 +-
 .../common/collect/ComparisonChain.java       |   37 +-
 .../common/collect/CompoundOrdering.java      |   10 +-
 .../common/collect/ComputationException.java  |    5 +-
 .../collect/ConcurrentHashMultiset.java       |   48 +-
 .../collect/ConsumingQueueIterator.java       |   19 +-
 .../google/common/collect/ContiguousSet.java  |   24 +-
 .../src/com/google/common/collect/Count.java  |    5 +-
 .../src/com/google/common/collect/Cut.java    |   39 +-
 .../common/collect/DenseImmutableTable.java   |   33 +-
 .../DescendingImmutableSortedMultiset.java    |    7 +-
 .../collect/DescendingImmutableSortedSet.java |   11 +-
 .../common/collect/DescendingMultiset.java    |   33 +-
 .../google/common/collect/DiscreteDomain.java |   19 +-
 .../ElementTypesAreNonnullByDefault.java      |   41 +
 .../common/collect/EmptyContiguousSet.java    |   13 +-
 .../collect/EmptyImmutableListMultimap.java   |    1 +
 .../collect/EmptyImmutableSetMultimap.java    |    1 +
 .../com/google/common/collect/EnumBiMap.java  |    3 +-
 .../google/common/collect/EnumHashBiMap.java  |   25 +-
 .../google/common/collect/EnumMultiset.java   |   20 +-
 .../google/common/collect/EvictingQueue.java  |   27 +-
 .../common/collect/ExplicitOrdering.java      |    5 +-
 .../common/collect/FilteredEntryMultimap.java |   50 +-
 .../collect/FilteredEntrySetMultimap.java     |   13 +-
 .../collect/FilteredKeyListMultimap.java      |   14 +-
 .../common/collect/FilteredKeyMultimap.java   |   41 +-
 .../collect/FilteredKeySetMultimap.java       |   16 +-
 .../common/collect/FilteredMultimap.java      |    5 +-
 .../collect/FilteredMultimapValues.java       |   11 +-
 .../common/collect/FilteredSetMultimap.java   |    5 +-
 .../google/common/collect/FluentIterable.java |   76 +-
 .../collect/ForwardingBlockingDeque.java      |    5 +
 .../common/collect/ForwardingCollection.java  |   28 +-
 .../collect/ForwardingConcurrentMap.java      |    6 +-
 .../common/collect/ForwardingDeque.java       |   29 +-
 .../ForwardingImmutableCollection.java        |    1 +
 .../collect/ForwardingImmutableList.java      |    1 +
 .../collect/ForwardingImmutableMap.java       |    1 +
 .../collect/ForwardingImmutableSet.java       |    1 +
 .../common/collect/ForwardingIterator.java    |    6 +-
 .../google/common/collect/ForwardingList.java |   28 +-
 .../collect/ForwardingListIterator.java       |   11 +-
 .../collect/ForwardingListMultimap.java       |   14 +-
 .../google/common/collect/ForwardingMap.java  |   31 +-
 .../common/collect/ForwardingMapEntry.java    |   16 +-
 .../common/collect/ForwardingMultimap.java    |   27 +-
 .../common/collect/ForwardingMultiset.java    |   33 +-
 .../collect/ForwardingNavigableMap.java       |   91 +-
 .../collect/ForwardingNavigableSet.java       |   58 +-
 .../common/collect/ForwardingObject.java      |    1 +
 .../common/collect/ForwardingQueue.java       |   16 +-
 .../google/common/collect/ForwardingSet.java  |   11 +-
 .../common/collect/ForwardingSetMultimap.java |   14 +-
 .../common/collect/ForwardingSortedMap.java   |   41 +-
 .../collect/ForwardingSortedMultiset.java     |   29 +-
 .../common/collect/ForwardingSortedSet.java   |   52 +-
 .../collect/ForwardingSortedSetMultimap.java  |   16 +-
 .../common/collect/ForwardingTable.java       |   31 +-
 .../google/common/collect/GeneralRange.java   |   95 +-
 .../google/common/collect/GwtTransient.java   |    1 +
 .../google/common/collect/HashBasedTable.java |   43 +-
 .../com/google/common/collect/HashBiMap.java  |  210 +--
 .../google/common/collect/HashMultimap.java   |   17 +-
 .../google/common/collect/HashMultiset.java   |   15 +-
 .../com/google/common/collect/Hashing.java    |    5 +-
 .../common/collect/ImmutableAsList.java       |    4 +-
 .../google/common/collect/ImmutableBiMap.java |  221 +++-
 .../collect/ImmutableClassToInstanceMap.java  |   16 +-
 .../common/collect/ImmutableCollection.java   |   45 +-
 .../google/common/collect/ImmutableEntry.java |   19 +-
 .../common/collect/ImmutableEnumMap.java      |   10 +-
 .../common/collect/ImmutableEnumSet.java      |    6 +-
 .../google/common/collect/ImmutableList.java  |   32 +-
 .../common/collect/ImmutableListMultimap.java |   24 +-
 .../google/common/collect/ImmutableMap.java   |  453 ++++++-
 .../common/collect/ImmutableMapEntrySet.java  |    8 +-
 .../common/collect/ImmutableMapKeySet.java    |    5 +-
 .../common/collect/ImmutableMapValues.java    |    5 +-
 .../common/collect/ImmutableMultimap.java     |   68 +-
 .../common/collect/ImmutableMultiset.java     |   54 +-
 ...eMultisetGwtSerializationDependencies.java |    1 +
 .../common/collect/ImmutableRangeMap.java     |   15 +-
 .../common/collect/ImmutableRangeSet.java     |   23 +-
 .../google/common/collect/ImmutableSet.java   |   37 +-
 .../common/collect/ImmutableSetMultimap.java  |   44 +-
 .../common/collect/ImmutableSortedMap.java    |  296 ++++-
 .../ImmutableSortedMapFauxverideShim.java     |  157 +++
 .../collect/ImmutableSortedMultiset.java      |   19 +-
 ...ImmutableSortedMultisetFauxverideShim.java |   10 +
 .../common/collect/ImmutableSortedSet.java    |   33 +-
 .../ImmutableSortedSetFauxverideShim.java     |   11 +
 .../google/common/collect/ImmutableTable.java |   45 +-
 .../common/collect/IndexedImmutableSet.java   |    4 +-
 .../com/google/common/collect/Interner.java   |    3 +-
 .../com/google/common/collect/Interners.java  |   20 +-
 .../com/google/common/collect/Iterables.java  |  163 ++-
 .../com/google/common/collect/Iterators.java  |  258 ++--
 .../collect/LexicographicalOrdering.java      |    9 +-
 .../common/collect/LinkedHashMultimap.java    |  142 +-
 .../common/collect/LinkedHashMultiset.java    |   19 +-
 .../common/collect/LinkedListMultimap.java    |  184 +--
 .../google/common/collect/ListMultimap.java   |   18 +-
 .../src/com/google/common/collect/Lists.java  |  177 +--
 .../google/common/collect/MapDifference.java  |   14 +-
 .../com/google/common/collect/MapMaker.java   |    9 +-
 .../common/collect/MapMakerInternalMap.java   |  108 +-
 .../src/com/google/common/collect/Maps.java   | 1021 ++++++++++-----
 .../common/collect/MinMaxPriorityQueue.java   |   55 +-
 .../com/google/common/collect/Multimap.java   |   33 +-
 .../common/collect/MultimapBuilder.java       |  104 +-
 .../com/google/common/collect/Multimaps.java  |  330 +++--
 .../com/google/common/collect/Multiset.java   |   36 +-
 .../com/google/common/collect/Multisets.java  |  149 ++-
 .../collect/MutableClassToInstanceMap.java    |   27 +-
 .../common/collect/NaturalOrdering.java       |   32 +-
 .../google/common/collect/NullnessCasts.java  |   68 +
 .../common/collect/NullsFirstOrdering.java    |   22 +-
 .../common/collect/NullsLastOrdering.java     |   22 +-
 .../google/common/collect/ObjectArrays.java   |   36 +-
 .../common/collect/ObjectCountHashMap.java    |   47 +-
 .../collect/ObjectCountLinkedHashMap.java     |   18 +-
 .../com/google/common/collect/Ordering.java   |   54 +-
 .../common/collect/ParametricNullness.java    |   52 +
 .../common/collect/PeekingIterator.java       |    8 +-
 .../com/google/common/collect/Platform.java   |   36 +-
 .../src/com/google/common/collect/Queues.java |   18 +-
 .../src/com/google/common/collect/Range.java  |   26 +-
 .../com/google/common/collect/RangeMap.java   |   15 +-
 .../com/google/common/collect/RangeSet.java   |    8 +-
 .../common/collect/RegularContiguousSet.java  |   29 +-
 .../collect/RegularImmutableAsList.java       |    7 +-
 .../common/collect/RegularImmutableBiMap.java |   32 +-
 .../common/collect/RegularImmutableList.java  |   14 +-
 .../common/collect/RegularImmutableMap.java   |  248 +++-
 .../collect/RegularImmutableMultiset.java     |   14 +-
 .../common/collect/RegularImmutableSet.java   |   30 +-
 .../RegularImmutableSortedMultiset.java       |    7 +-
 .../collect/RegularImmutableSortedSet.java    |   18 +-
 .../common/collect/RegularImmutableTable.java |   38 +-
 .../collect/ReverseNaturalOrdering.java       |   25 +-
 .../common/collect/ReverseOrdering.java       |   21 +-
 .../google/common/collect/RowSortedTable.java |    6 +-
 .../google/common/collect/Serialization.java  |   35 +-
 .../google/common/collect/SetMultimap.java    |   21 +-
 .../src/com/google/common/collect/Sets.java   |  286 +++--
 .../common/collect/SingletonImmutableSet.java |   38 +-
 .../collect/SingletonImmutableTable.java      |    1 +
 .../google/common/collect/SortedIterable.java |    4 +-
 .../common/collect/SortedIterables.java       |    5 +-
 .../google/common/collect/SortedLists.java    |   58 +-
 .../common/collect/SortedMapDifference.java   |    5 +-
 .../google/common/collect/SortedMultiset.java |   22 +-
 .../common/collect/SortedMultisetBridge.java  |    4 +-
 .../common/collect/SortedMultisets.java       |   55 +-
 .../common/collect/SortedSetMultimap.java     |   21 +-
 .../common/collect/SparseImmutableTable.java  |   20 +-
 .../collect/StandardRowSortedTable.java       |    3 +
 .../google/common/collect/StandardTable.java  |  192 ++-
 .../google/common/collect/Synchronized.java   |  425 +++---
 .../src/com/google/common/collect/Table.java  |   52 +-
 .../src/com/google/common/collect/Tables.java |  153 ++-
 .../google/common/collect/TopKSelector.java   |   44 +-
 .../common/collect/TransformedIterator.java   |    9 +-
 .../collect/TransformedListIterator.java      |   11 +-
 .../google/common/collect/TreeBasedTable.java |   73 +-
 .../google/common/collect/TreeMultimap.java   |   17 +-
 .../google/common/collect/TreeMultiset.java   |  237 ++--
 .../google/common/collect/TreeRangeMap.java   |   74 +-
 .../google/common/collect/TreeRangeSet.java   |   78 +-
 .../google/common/collect/TreeTraverser.java  |    3 +
 .../common/collect/UnmodifiableIterator.java  |    4 +-
 .../collect/UnmodifiableListIterator.java     |   10 +-
 .../collect/UnmodifiableSortedMultiset.java   |   23 +-
 .../common/collect/UsingToStringOrdering.java |    1 +
 .../common/escape/ArrayBasedCharEscaper.java  |    8 +-
 .../common/escape/ArrayBasedEscaperMap.java   |    5 +-
 .../escape/ArrayBasedUnicodeEscaper.java      |   14 +-
 .../com/google/common/escape/CharEscaper.java |    5 +-
 .../common/escape/CharEscaperBuilder.java     |   12 +-
 .../ElementTypesAreNonnullByDefault.java      |   41 +
 .../src/com/google/common/escape/Escaper.java |    9 +-
 .../com/google/common/escape/Escapers.java    |   22 +-
 .../common/escape/ParametricNullness.java     |   52 +
 .../com/google/common/escape/Platform.java    |    1 +
 .../google/common/escape/UnicodeEscaper.java  |    5 +-
 .../eventbus/AllowConcurrentEvents.java       |    3 +-
 .../google/common/eventbus/AsyncEventBus.java |    3 +-
 .../com/google/common/eventbus/DeadEvent.java |    3 +-
 .../google/common/eventbus/Dispatcher.java    |    1 +
 .../ElementTypesAreNonnullByDefault.java      |   41 +
 .../com/google/common/eventbus/EventBus.java  |   59 +-
 .../common/eventbus/ParametricNullness.java   |   52 +
 .../com/google/common/eventbus/Subscribe.java |    3 +-
 .../google/common/eventbus/Subscriber.java    |   20 +-
 .../eventbus/SubscriberExceptionContext.java  |    5 +-
 .../eventbus/SubscriberExceptionHandler.java  |    2 +
 .../common/eventbus/SubscriberRegistry.java   |    5 +-
 .../common/graph/AbstractBaseGraph.java       |   29 +-
 .../AbstractDirectedNetworkConnections.java   |   22 +-
 .../google/common/graph/AbstractGraph.java    |    5 +-
 .../common/graph/AbstractGraphBuilder.java    |    1 +
 .../google/common/graph/AbstractNetwork.java  |   11 +-
 .../AbstractUndirectedNetworkConnections.java |   14 +-
 .../common/graph/AbstractValueGraph.java      |   10 +-
 .../com/google/common/graph/BaseGraph.java    |    1 +
 .../graph/DirectedGraphConnections.java       |   91 +-
 .../DirectedMultiNetworkConnections.java      |   13 +-
 .../graph/DirectedNetworkConnections.java     |    6 +-
 .../google/common/graph/EdgesConnecting.java  |    7 +-
 .../com/google/common/graph/ElementOrder.java |   19 +-
 .../ElementTypesAreNonnullByDefault.java      |   41 +
 .../com/google/common/graph/EndpointPair.java |   16 +-
 .../common/graph/EndpointPairIterator.java    |   30 +-
 .../google/common/graph/ForwardingGraph.java  |    3 +-
 .../common/graph/ForwardingNetwork.java       |    6 +-
 .../common/graph/ForwardingValueGraph.java    |   13 +-
 .../src/com/google/common/graph/Graph.java    |    5 +-
 .../com/google/common/graph/GraphBuilder.java |    3 +-
 .../google/common/graph/GraphConnections.java |    7 +-
 .../google/common/graph/GraphConstants.java   |    2 +
 .../src/com/google/common/graph/Graphs.java   |   34 +-
 .../google/common/graph/ImmutableGraph.java   |    5 +-
 .../google/common/graph/ImmutableNetwork.java |   34 +-
 .../common/graph/ImmutableValueGraph.java     |   18 +-
 .../google/common/graph/IncidentEdgeSet.java  |   11 +-
 .../google/common/graph/MapIteratorCache.java |   46 +-
 .../common/graph/MapRetrievalCache.java       |   22 +-
 .../common/graph/MultiEdgesConnecting.java    |    8 +-
 .../com/google/common/graph/MutableGraph.java |    1 +
 .../google/common/graph/MutableNetwork.java   |    1 +
 .../common/graph/MutableValueGraph.java       |    6 +
 .../src/com/google/common/graph/Network.java  |    9 +-
 .../google/common/graph/NetworkBuilder.java   |    1 +
 .../common/graph/NetworkConnections.java      |    3 +
 .../common/graph/ParametricNullness.java      |   52 +
 .../common/graph/PredecessorsFunction.java    |    1 +
 .../common/graph/StandardMutableGraph.java    |    3 +-
 .../common/graph/StandardMutableNetwork.java  |    7 +-
 .../graph/StandardMutableValueGraph.java      |   15 +-
 .../google/common/graph/StandardNetwork.java  |   18 +-
 .../common/graph/StandardValueGraph.java      |   41 +-
 .../common/graph/SuccessorsFunction.java      |    1 +
 .../com/google/common/graph/Traverser.java    |   47 +-
 .../graph/UndirectedGraphConnections.java     |   15 +-
 .../UndirectedMultiNetworkConnections.java    |   12 +-
 .../graph/UndirectedNetworkConnections.java   |    5 +-
 .../com/google/common/graph/ValueGraph.java   |   13 +-
 .../common/graph/ValueGraphBuilder.java       |    1 +
 .../common/hash/AbstractByteHasher.java       |    1 +
 .../hash/AbstractCompositeHashFunction.java   |    7 +-
 .../common/hash/AbstractHashFunction.java     |    5 +-
 .../google/common/hash/AbstractHasher.java    |    5 +-
 .../AbstractNonStreamingHashFunction.java     |    1 +
 .../common/hash/AbstractStreamingHasher.java  |    1 +
 .../com/google/common/hash/BloomFilter.java   |   59 +-
 .../common/hash/BloomFilterStrategies.java    |   77 +-
 .../common/hash/ChecksumHashFunction.java     |    1 +
 .../common/hash/Crc32cHashFunction.java       |    1 +
 .../hash/ElementTypesAreNonnullByDefault.java |   41 +
 .../common/hash/FarmHashFingerprint64.java    |    3 +-
 .../google/common/hash/Fingerprint2011.java   |  198 +++
 .../src/com/google/common/hash/Funnel.java    |    6 +-
 .../src/com/google/common/hash/Funnels.java   |   16 +-
 .../src/com/google/common/hash/HashCode.java  |    5 +-
 .../com/google/common/hash/HashFunction.java  |    7 +-
 .../src/com/google/common/hash/Hasher.java    |    5 +-
 .../src/com/google/common/hash/Hashing.java   |   90 +-
 .../common/hash/HashingInputStream.java       |    1 +
 .../common/hash/HashingOutputStream.java      |    1 +
 .../google/common/hash/ImmutableSupplier.java |    2 +
 .../common/hash/Java8Compatibility.java       |    1 +
 .../common/hash/LittleEndianByteArray.java    |    3 +-
 .../com/google/common/hash/LongAddable.java   |    2 +
 .../com/google/common/hash/LongAddables.java  |    4 +-
 .../src/com/google/common/hash/LongAdder.java |    1 +
 .../google/common/hash/MacHashFunction.java   |    3 +-
 .../hash/MessageDigestHashFunction.java       |    3 +-
 .../common/hash/Murmur3_128HashFunction.java  |    5 +-
 .../common/hash/Murmur3_32HashFunction.java   |   31 +-
 .../common/hash/ParametricNullness.java       |   52 +
 .../com/google/common/hash/PrimitiveSink.java |    1 +
 .../google/common/hash/SipHashFunction.java   |    5 +-
 .../src/com/google/common/hash/Striped64.java |   10 +-
 .../html/ElementTypesAreNonnullByDefault.java |   41 +
 .../com/google/common/html/HtmlEscapers.java  |    1 +
 .../common/html/ParametricNullness.java       |   52 +
 .../google/common/io/AppendableWriter.java    |   13 +-
 .../com/google/common/io/BaseEncoding.java    |   58 +-
 .../google/common/io/ByteArrayDataInput.java  |    3 +
 .../google/common/io/ByteArrayDataOutput.java |    1 +
 .../com/google/common/io/ByteProcessor.java   |    5 +-
 .../src/com/google/common/io/ByteSink.java    |    1 +
 .../src/com/google/common/io/ByteSource.java  |   21 +-
 .../src/com/google/common/io/ByteStreams.java |   45 +-
 .../google/common/io/CharSequenceReader.java  |   21 +-
 .../src/com/google/common/io/CharSink.java    |    1 +
 .../src/com/google/common/io/CharSource.java  |   26 +-
 .../src/com/google/common/io/CharStreams.java |   14 +-
 .../src/com/google/common/io/Closeables.java  |    9 +-
 .../src/com/google/common/io/Closer.java      |   41 +-
 .../google/common/io/CountingInputStream.java |    1 +
 .../common/io/CountingOutputStream.java       |    1 +
 .../io/ElementTypesAreNonnullByDefault.java   |   41 +
 .../common/io/FileBackedOutputStream.java     |   31 +-
 .../com/google/common/io/FileWriteMode.java   |    1 +
 .../guava/src/com/google/common/io/Files.java |   85 +-
 .../src/com/google/common/io/Flushables.java  |    1 +
 .../google/common/io/Java8Compatibility.java  |    9 +
 .../src/com/google/common/io/LineBuffer.java  |    1 +
 .../com/google/common/io/LineProcessor.java   |    5 +-
 .../src/com/google/common/io/LineReader.java  |    6 +-
 .../io/LittleEndianDataInputStream.java       |    1 +
 .../io/LittleEndianDataOutputStream.java      |    1 +
 .../google/common/io/MultiInputStream.java    |    8 +-
 .../src/com/google/common/io/MultiReader.java |   10 +-
 .../google/common/io/ParametricNullness.java  |   52 +
 .../common/io/PatternFilenameFilter.java      |   17 +-
 .../google/common/io/ReaderInputStream.java   |    1 +
 .../src/com/google/common/io/Resources.java   |   11 +-
 .../google/common/math/BigDecimalMath.java    |    1 +
 .../google/common/math/BigIntegerMath.java    |    1 +
 .../com/google/common/math/DoubleMath.java    |    3 +-
 .../com/google/common/math/DoubleUtils.java   |    1 +
 .../math/ElementTypesAreNonnullByDefault.java |   41 +
 .../src/com/google/common/math/IntMath.java   |    1 +
 .../common/math/LinearTransformation.java     |    6 +-
 .../src/com/google/common/math/LongMath.java  |    3 +-
 .../google/common/math/MathPreconditions.java |   16 +-
 .../com/google/common/math/PairedStats.java   |    5 +-
 .../common/math/PairedStatsAccumulator.java   |    1 +
 .../common/math/ParametricNullness.java       |   52 +
 .../src/com/google/common/math/Quantiles.java |    1 +
 .../src/com/google/common/math/Stats.java     |    5 +-
 .../google/common/math/StatsAccumulator.java  |    1 +
 .../google/common/math/ToDoubleRounder.java   |    1 +
 .../net/ElementTypesAreNonnullByDefault.java  |   41 +
 .../com/google/common/net/HostAndPort.java    |   22 +-
 .../com/google/common/net/HostSpecifier.java  |   19 +-
 .../com/google/common/net/HttpHeaders.java    |  187 ++-
 .../com/google/common/net/InetAddresses.java  |   63 +-
 .../google/common/net/InternetDomainName.java |   17 +-
 .../src/com/google/common/net/MediaType.java  |   38 +-
 .../google/common/net/ParametricNullness.java |   52 +
 .../com/google/common/net/PercentEscaper.java |    5 +-
 .../com/google/common/net/UrlEscapers.java    |    1 +
 .../com/google/common/net/package-info.java   |    2 +
 .../google/common/primitives/Booleans.java    |   11 +-
 .../com/google/common/primitives/Bytes.java   |   11 +-
 .../com/google/common/primitives/Chars.java   |   11 +-
 .../com/google/common/primitives/Doubles.java |   13 +-
 .../primitives/DoublesMethodsForWeb.java      |    1 +
 .../ElementTypesAreNonnullByDefault.java      |   41 +
 .../com/google/common/primitives/Floats.java  |   13 +-
 .../primitives/FloatsMethodsForWeb.java       |    1 +
 .../primitives/ImmutableDoubleArray.java      |   13 +-
 .../common/primitives/ImmutableIntArray.java  |   13 +-
 .../common/primitives/ImmutableLongArray.java |   13 +-
 .../com/google/common/primitives/Ints.java    |   15 +-
 .../common/primitives/IntsMethodsForWeb.java  |    1 +
 .../com/google/common/primitives/Longs.java   |   15 +-
 .../common/primitives/ParametricNullness.java |   52 +
 .../common/primitives/ParseRequest.java       |    1 +
 .../google/common/primitives/Platform.java    |    1 +
 .../google/common/primitives/Primitives.java  |    1 +
 .../com/google/common/primitives/Shorts.java  |   11 +-
 .../primitives/ShortsMethodsForWeb.java       |    1 +
 .../google/common/primitives/SignedBytes.java |    1 +
 .../common/primitives/UnsignedBytes.java      |    9 +-
 .../common/primitives/UnsignedInteger.java    |    5 +-
 .../common/primitives/UnsignedInts.java       |    1 +
 .../common/primitives/UnsignedLong.java       |   28 +-
 .../common/primitives/UnsignedLongs.java      |    1 +
 .../reflect/AbstractInvocationHandler.java    |   14 +-
 .../com/google/common/reflect/ClassPath.java  |   65 +-
 .../com/google/common/reflect/Element.java    |  178 ---
 .../ElementTypesAreNonnullByDefault.java      |   41 +
 .../reflect/ImmutableTypeToInstanceMap.java   |   17 +-
 .../com/google/common/reflect/Invokable.java  |  186 ++-
 .../reflect/MutableTypeToInstanceMap.java     |   53 +-
 .../com/google/common/reflect/Parameter.java  |   20 +-
 .../common/reflect/ParametricNullness.java    |   52 +
 .../com/google/common/reflect/Reflection.java |    3 +-
 .../google/common/reflect/TypeCapture.java    |    1 +
 .../google/common/reflect/TypeParameter.java  |   17 +-
 .../google/common/reflect/TypeResolver.java   |   25 +-
 .../common/reflect/TypeToInstanceMap.java     |   20 +-
 .../com/google/common/reflect/TypeToken.java  |   93 +-
 .../google/common/reflect/TypeVisitor.java    |    4 +-
 .../src/com/google/common/reflect/Types.java  |   56 +-
 .../concurrent/AbstractCatchingFuture.java    |   38 +-
 .../AbstractExecutionThreadService.java       |    1 +
 .../util/concurrent/AbstractFuture.java       |  260 +++-
 .../util/concurrent/AbstractIdleService.java  |    1 +
 .../AbstractListeningExecutorService.java     |   13 +-
 .../concurrent/AbstractScheduledService.java  |  178 ++-
 .../util/concurrent/AbstractService.java      |   15 +-
 .../concurrent/AbstractTransformFuture.java   |   39 +-
 .../util/concurrent/AggregateFuture.java      |  103 +-
 .../util/concurrent/AggregateFutureState.java |   41 +-
 .../common/util/concurrent/AsyncCallable.java |    6 +-
 .../common/util/concurrent/AsyncFunction.java |    7 +-
 .../common/util/concurrent/AtomicDouble.java  |    2 +
 .../util/concurrent/AtomicDoubleArray.java    |    6 +-
 .../common/util/concurrent/AtomicLongMap.java |    5 +-
 .../common/util/concurrent/Atomics.java       |   20 +-
 .../common/util/concurrent/Callables.java     |   73 +-
 .../common/util/concurrent/ClosingFuture.java |  317 +++--
 .../util/concurrent/CollectionFuture.java     |   34 +-
 .../util/concurrent/CombinedFuture.java       |   47 +-
 .../concurrent/CycleDetectingLockFactory.java |   39 +-
 .../util/concurrent/DirectExecutor.java       |    1 +
 .../ElementTypesAreNonnullByDefault.java      |   41 +
 .../util/concurrent/ExecutionError.java       |   15 +-
 .../common/util/concurrent/ExecutionList.java |   10 +-
 .../util/concurrent/ExecutionSequencer.java   |  168 ++-
 .../util/concurrent/FakeTimeLimiter.java      |   10 +-
 .../common/util/concurrent/FluentFuture.java  |   24 +-
 .../concurrent/ForwardingBlockingDeque.java   |    5 +
 .../concurrent/ForwardingBlockingQueue.java   |    3 +
 .../util/concurrent/ForwardingCondition.java  |    1 +
 .../concurrent/ForwardingExecutorService.java |   18 +-
 .../concurrent/ForwardingFluentFuture.java    |    6 +-
 .../util/concurrent/ForwardingFuture.java     |   10 +-
 .../ForwardingListenableFuture.java           |    8 +-
 .../ForwardingListeningExecutorService.java   |    7 +-
 .../util/concurrent/ForwardingLock.java       |    1 +
 .../util/concurrent/FutureCallback.java       |    7 +-
 .../common/util/concurrent/Futures.java       |  208 +--
 .../util/concurrent/FuturesGetChecked.java    |   59 +-
 ...GwtFluentFutureCatchingSpecialization.java |    5 +-
 .../GwtFuturesCatchingSpecialization.java     |    1 +
 .../util/concurrent/ImmediateFuture.java      |   20 +-
 .../util/concurrent/InterruptibleTask.java    |  203 +--
 .../util/concurrent/JdkFutureAdapters.java    |   43 +-
 .../util/concurrent/ListenableFuture.java     |   19 +-
 .../util/concurrent/ListenableFutureTask.java |   18 +-
 .../concurrent/ListenableScheduledFuture.java |    7 +-
 .../util/concurrent/ListenerCallQueue.java    |    3 +-
 .../concurrent/ListeningExecutorService.java  |   11 +-
 .../ListeningScheduledExecutorService.java    |    5 +-
 .../common/util/concurrent/Monitor.java       |   17 +-
 .../common/util/concurrent/MoreExecutors.java |   82 +-
 .../common/util/concurrent/NullnessCasts.java |   76 ++
 .../OverflowAvoidingLockSupport.java          |    5 +-
 .../util/concurrent/ParametricNullness.java   |   52 +
 .../common/util/concurrent/Partially.java     |    1 +
 .../common/util/concurrent/Platform.java      |    5 +-
 .../common/util/concurrent/RateLimiter.java   |    5 +-
 .../common/util/concurrent/Runnables.java     |    1 +
 .../util/concurrent/SequentialExecutor.java   |   10 +-
 .../common/util/concurrent/Service.java       |   46 +-
 .../util/concurrent/ServiceManager.java       |   10 +-
 .../util/concurrent/ServiceManagerBridge.java |    1 +
 .../util/concurrent/SettableFuture.java       |   12 +-
 .../util/concurrent/SimpleTimeLimiter.java    |   35 +-
 .../util/concurrent/SmoothRateLimiter.java    |    1 +
 .../common/util/concurrent/Striped.java       |   98 +-
 .../util/concurrent/ThreadFactoryBuilder.java |   28 +-
 .../common/util/concurrent/TimeLimiter.java   |    7 +-
 .../common/util/concurrent/TimeoutFuture.java |   19 +-
 .../TrustedListenableFutureTask.java          |   56 +-
 .../concurrent/UncaughtExceptionHandlers.java |    1 +
 .../UncheckedExecutionException.java          |   15 +-
 .../concurrent/UncheckedTimeoutException.java |    9 +-
 .../util/concurrent/Uninterruptibles.java     |   14 +-
 .../concurrent/WrappingExecutorService.java   |   40 +-
 .../WrappingScheduledExecutorService.java     |    5 +-
 .../xml/ElementTypesAreNonnullByDefault.java  |   41 +
 .../google/common/xml/ParametricNullness.java |   52 +
 .../com/google/common/xml/XmlEscapers.java    |    3 +-
 .../publicsuffix/PublicSuffixPatterns.java    |    6 +-
 .../thirdparty/publicsuffix/TrieParser.java   |    2 +-
 android/pom.xml                               |  104 +-
 azure-pipelines.yml                           |    2 +-
 .../util/concurrent/ListenableFuture.java     |   19 +-
 guava-bom/pom.xml                             |    2 +-
 guava-gwt/pom.xml                             |    8 +-
 .../com/google/common/cache/LocalCache.java   |    2 +-
 .../collect/ForwardingImmutableMap.java       |    4 +-
 .../google/common/collect/ImmutableBiMap.java |   96 +-
 .../google/common/collect/ImmutableMap.java   |  151 ++-
 .../google/common/collect/ImmutableSet.java   |   19 +
 .../common/collect/ImmutableSortedMap.java    |  126 ++
 .../com/google/common/collect/Platform.java   |   10 +
 .../common/collect/RegularImmutableMap.java   |    6 +-
 .../util/concurrent/AbstractFuture.java       |    3 +
 .../GwtFuturesCatchingSpecialization.java     |   20 -
 .../util/concurrent/InterruptibleTask.java    |   19 +-
 .../common/annotations/Annotations.gwt.xml    |   37 +-
 .../src/com/google/common/base/Base.gwt.xml   |   39 +-
 .../src/com/google/common/cache/Cache.gwt.xml |   38 +-
 .../com/google/common/collect/Collect.gwt.xml |   39 +-
 .../com/google/common/escape/Escape.gwt.xml   |   38 +-
 .../src/com/google/common/html/Html.gwt.xml   |   36 +-
 guava-gwt/src/com/google/common/io/Io.gwt.xml |   38 +-
 .../src/com/google/common/math/Math.gwt.xml   |   38 +-
 .../src/com/google/common/net/Net.gwt.xml     |   41 +-
 .../common/primitives/Primitives.gwt.xml      |   39 +-
 .../common/util/concurrent/Concurrent.gwt.xml |   40 +-
 .../src/com/google/common/xml/Xml.gwt.xml     |   36 +-
 .../publicsuffix/PublicSuffixPatterns.gwt.xml |   37 +-
 .../publicsuffix/PublicSuffixType.gwt.xml     |   35 +-
 .../common/collect/testing/Testing.gwt.xml    |   40 +-
 .../collect/testing/google/Google.gwt.xml     |   40 +-
 .../common/escape/testing/Testing.gwt.xml     |   37 +-
 .../com/google/common/testing/Testing.gwt.xml |   40 +-
 guava-testlib/README.md                       |    4 +-
 guava-testlib/pom.xml                         |    2 +-
 .../testing/AbstractContainerTester.java      |    4 +-
 .../collect/testing/AbstractMapTester.java    |    8 +-
 .../testing/CollectionTestSuiteBuilder.java   |    2 +
 .../testing/DerivedCollectionGenerators.java  |   13 +-
 .../FeatureSpecificTestSuiteBuilder.java      |   20 +-
 .../common/collect/testing/Helpers.java       |   18 +-
 .../collect/testing/ListTestSuiteBuilder.java |    2 +
 .../collect/testing/MapInterfaceTest.java     |  212 +--
 .../collect/testing/MapTestSuiteBuilder.java  |    8 +
 .../collect/testing/MinimalCollection.java    |    4 +-
 .../collect/testing/MinimalIterable.java      |    4 +-
 .../common/collect/testing/MinimalSet.java    |    4 +-
 .../testing/NavigableMapTestSuiteBuilder.java |    4 +-
 .../testing/NavigableSetTestSuiteBuilder.java |    9 +-
 .../collect/testing/OneSizeGenerator.java     |    2 +-
 .../ReserializingTestCollectionGenerator.java |    2 +-
 .../ReserializingTestSetGenerator.java        |    2 +-
 .../common/collect/testing/SafeTreeSet.java   |    8 +-
 .../collect/testing/SetTestSuiteBuilder.java  |    2 +
 .../testing/SortedMapInterfaceTest.java       |    6 +-
 .../testing/SortedMapTestSuiteBuilder.java    |   10 +-
 .../testing/SortedSetTestSuiteBuilder.java    |   13 +-
 .../collect/testing/SpliteratorTester.java    |    3 +-
 .../collect/testing/features/FeatureUtil.java |    8 +-
 .../google/AbstractMultimapTester.java        |   10 +-
 .../testing/google/BiMapTestSuiteBuilder.java |    6 +
 .../DerivedGoogleCollectionGenerators.java    |    6 +-
 .../collect/testing/google/MapGenerators.java |   12 +-
 .../google/MultimapTestSuiteBuilder.java      |   12 +
 .../google/MultisetNavigationTester.java      |    2 +-
 .../google/MultisetTestSuiteBuilder.java      |    6 +
 .../google/SetMultimapAsMapTester.java        |    2 +-
 .../SortedMultisetTestSuiteBuilder.java       |   18 +-
 .../google/SortedSetMultimapAsMapTester.java  |    2 +-
 .../google/UnmodifiableCollectionTests.java   |    4 +-
 .../testers/CollectionForEachTester.java      |    4 +-
 .../testers/CollectionIteratorTester.java     |    6 +-
 .../testers/CollectionToArrayTester.java      |    4 +-
 .../testing/testers/MapReplaceAllTester.java  |    4 +-
 .../testers/NavigableSetNavigationTester.java |    2 +-
 .../common/escape/testing/EscaperAsserts.java |    2 -
 .../testing/AbstractPackageSanityTests.java   |   20 +-
 .../common/testing/ArbitraryInstances.java    |    4 +-
 .../common/testing/CollectorTester.java       |    2 -
 .../google/common/testing/EqualsTester.java   |    4 +-
 .../common/testing/EquivalenceTester.java     |    7 +-
 .../com/google/common/testing/FakeTicker.java |    2 -
 .../testing/ForwardingWrapperTester.java      |    6 +-
 .../common/testing/FreshValueGenerator.java   |  242 ++--
 .../google/common/testing/GcFinalization.java |   35 +-
 .../common/testing/NullPointerTester.java     |   52 +-
 .../common/testing/RelationshipTester.java    |    2 +-
 .../common/testing/SerializableTester.java    |    3 -
 .../google/common/testing/TestLogHandler.java |    2 -
 .../testing/AbstractListenableFutureTest.java |  109 +-
 .../testing/MockFutureListener.java           |    8 +-
 .../SameThreadScheduledExecutorService.java   |    4 +-
 .../concurrent/testing/TestingExecutors.java  |    6 +-
 .../FeatureSpecificTestSuiteBuilderTest.java  |    6 +-
 .../testing/MapTestSuiteBuilderTests.java     |   92 ++
 .../common/testing/EquivalenceTesterTest.java |    2 +-
 .../common/testing/NullPointerTesterTest.java |   43 +
 .../common/base/StringsRepeatBenchmark.java   |    6 +-
 .../common/base/ToStringHelperBenchmark.java  |    2 +
 ...ableSetHashFloodingDetectionBenchmark.java |   44 +
 .../google/common/collect/MapBenchmark.java   |    2 +-
 .../FuturesGetCheckedBenchmark.java           |    7 +-
 .../MonitorBasedArrayBlockingQueue.java       |   66 +-
 .../MonitorBasedPriorityBlockingQueue.java    |   60 +-
 guava-tests/pom.xml                           |    5 +-
 .../common/base/AbstractIteratorTest.java     |    2 +-
 .../com/google/common/base/AsciiTest.java     |   13 +-
 .../google/common/base/CharMatcherTest.java   |    2 +-
 .../com/google/common/base/OptionalTest.java  |    6 +
 .../google/common/base/PreconditionsTest.java |   19 +-
 .../common/base/StopwatchJavaTimeTest.java    |   37 +
 .../com/google/common/base/StopwatchTest.java |   11 -
 .../common/base/ToStringHelperTest.java       |   38 +-
 .../com/google/common/base/VerifyTest.java    |    8 +-
 .../google/common/cache/LocalCacheTest.java   |    2 +-
 .../common/collect/AbstractIteratorTest.java  |    1 +
 .../common/collect/AbstractMapEntryTest.java  |    3 +-
 .../collect/CompactHashMapFloodingTest.java   |   28 +
 .../common/collect/CompactHashMapTest.java    |    9 -
 .../collect/CompactHashSetFloodingTest.java   |   28 +
 .../common/collect/CompactHashSetTest.java    |    9 -
 .../CompactLinkedHashMapFloodingTest.java     |   21 +-
 .../collect/CompactLinkedHashMapTest.java     |    9 -
 .../CompactLinkedHashSetFloodingTest.java     |   28 +
 .../collect/CompactLinkedHashSetTest.java     |    9 -
 .../common/collect/DiscreteDomainTest.java    |   44 +
 .../common/collect/ForwardingMapTest.java     |    2 +-
 .../common/collect/ImmutableBiMapTest.java    |  173 ++-
 .../collect/ImmutableListMultimapTest.java    |   10 +
 .../common/collect/ImmutableMapTest.java      |  478 ++++++-
 .../common/collect/ImmutableMultimapTest.java |   11 +
 .../common/collect/ImmutableRangeSetTest.java |    4 +
 .../collect/ImmutableSetMultimapTest.java     |   10 +
 .../common/collect/ImmutableSetTest.java      |    6 +
 .../collect/ImmutableSortedMapTest.java       |  140 +-
 .../collect/ImmutableSortedSetTest.java       |    2 +-
 .../google/common/collect/IteratorsTest.java  |    4 +
 .../com/google/common/collect/ListsTest.java  |   16 +-
 .../google/common/collect/MapMakerTest.java   |   41 +-
 .../com/google/common/collect/MapsTest.java   |  100 +-
 .../common/collect/MoreCollectorsTest.java    |    8 +
 .../google/common/collect/MultimapsTest.java  |    3 +-
 .../com/google/common/collect/RangeTest.java  |   10 +
 .../collect/RegularImmutableAsListTest.java   |    3 +-
 .../common/collect/SetOperationsTest.java     |  166 ++-
 .../com/google/common/collect/SetsTest.java   |    1 +
 .../common/collect/SynchronizedDequeTest.java |    5 +-
 .../common/collect/SynchronizedMapTest.java   |   10 +-
 .../common/collect/SynchronizedQueueTest.java |    5 +-
 .../common/collect/TableCollectorsTest.java   |  407 +++---
 .../common/collect/TopKSelectorTest.java      |   11 +
 .../collect/UnmodifiableIteratorTest.java     |    1 +
 .../collect/UnmodifiableListIteratorTest.java |    3 +
 .../google/common/escape/EscapersTest.java    |    2 +-
 .../outside/AbstractEventBusTest.java         |   55 +
 .../AbstractNotAnnotatedInSuperclassTest.java |   61 +
 .../AnnotatedAndAbstractInSuperclassTest.java |   63 +
 .../AnnotatedNotAbstractInSuperclassTest.java |  116 ++
 .../AnnotatedSubscriberFinderTests.java       |  448 -------
 .../outside/BaseSubscriberFinderTest.java     |   53 +
 .../eventbus/outside/DeepInterfaceTest.java   |  153 +++
 ...rAbstractNorAnnotatedInSuperclassTest.java |   74 ++
 .../com/google/common/graph/MapCacheTest.java |   21 -
 .../google/common/hash/BloomFilterTest.java   |    5 +-
 .../common/hash/Fingerprint2011Test.java      |  233 ++++
 .../google/common/hash/HashFunctionEnum.java  |    1 +
 .../com/google/common/hash/HashTestUtils.java |    4 +-
 .../com/google/common/hash/HashingTest.java   |   19 +-
 .../google/common/hash/Murmur3Hash32Test.java |   79 +-
 .../com/google/common/io/ByteSourceTest.java  |    3 +-
 .../google/common/io/ByteSourceTester.java    |    2 +-
 .../com/google/common/io/ByteStreamsTest.java |   41 +-
 .../common/io/CharSequenceReaderTest.java     |    6 +-
 .../com/google/common/io/CharSourceTest.java  |    3 +-
 .../test/com/google/common/io/CloserTest.java |    6 +-
 .../io/LittleEndianDataInputStreamTest.java   |    1 +
 .../com/google/common/io/MoreFilesTest.java   |   12 +
 .../common/io/PatternFilenameFilterTest.java  |   13 +
 .../google/common/io/SourceSinkFactories.java |    4 +-
 .../google/common/io/SourceSinkTester.java    |    2 +-
 .../com/google/common/math/IntMathTest.java   |    7 +-
 .../common/math/MathPreconditionsTest.java    |   11 +
 .../common/math/QuantilesAlgorithm.java       |    4 +-
 .../com/google/common/math/QuantilesTest.java |    6 +-
 .../google/common/net/HostAndPortTest.java    |    7 +
 .../google/common/net/HostSpecifierTest.java  |    5 +-
 .../google/common/net/HttpHeadersTest.java    |    4 +-
 .../google/common/net/InetAddressesTest.java  |   28 +
 .../common/net/InternetDomainNameTest.java    |    4 +-
 .../com/google/common/net/MediaTypeTest.java  |    3 +-
 .../google/common/net/PercentEscaperTest.java |   13 +-
 .../common/primitives/BooleansTest.java       |    3 +-
 .../common/primitives/UnsignedLongTest.java   |   25 +-
 .../google/common/reflect/ElementTest.java    |  247 ----
 .../google/common/reflect/InvokableTest.java  |  193 ++-
 .../google/common/reflect/TypeTokenTest.java  |   16 +-
 .../AbstractAbstractFutureTest.java           |    1 -
 ...st.java => AbstractClosingFutureTest.java} |  193 +--
 .../AbstractExecutionThreadServiceTest.java   |    9 -
 .../AbstractFutureCancellationCauseTest.java  |    1 +
 .../util/concurrent/AbstractFutureTest.java   |    2 +-
 .../concurrent/AbstractIdleServiceTest.java   |    1 -
 .../AbstractScheduledServiceTest.java         |   90 +-
 .../util/concurrent/AbstractServiceTest.java  |    9 -
 .../concurrent/AtomicDoubleArrayTest.java     |  138 +-
 .../util/concurrent/AtomicDoubleTest.java     |  107 +-
 .../concurrent/AtomicLongMapBasherTest.java   |   34 +-
 .../util/concurrent/AtomicLongMapTest.java    |    6 +-
 .../ClosingFutureFinishToFutureTest.java      |   94 ++
 ...osingFutureFinishToValueAndCloserTest.java |  148 +++
 .../CycleDetectingLockFactoryTest.java        |    3 -
 .../util/concurrent/ExecutionListTest.java    |    3 -
 .../concurrent/ExecutionSequencerTest.java    |    3 -
 .../util/concurrent/FluentFutureTest.java     |    1 -
 .../concurrent/ForwardingObjectTester.java    |    2 +-
 .../concurrent/FuturesGetCheckedTest.java     |    5 +-
 .../common/util/concurrent/FuturesTest.java   |   31 +-
 .../concurrent/FuturesTransformAsyncTest.java |    1 -
 .../util/concurrent/GeneratedMonitorTest.java |    1 -
 .../concurrent/InterruptibleMonitorTest.java  |    1 -
 .../concurrent/InterruptibleTaskTest.java     |   54 +-
 .../util/concurrent/JSR166TestCase.java       |    2 +-
 .../concurrent/JdkFutureAdaptersTest.java     |    3 -
 .../concurrent/ListenableFutureTaskTest.java  |    3 -
 .../concurrent/ListenerCallQueueTest.java     |    2 -
 .../util/concurrent/MonitorTestCase.java      |    1 -
 .../util/concurrent/MoreExecutorsTest.java    |   32 +-
 .../concurrent/SequentialExecutorTest.java    |   10 +-
 .../util/concurrent/ServiceManagerTest.java   |   32 +-
 .../util/concurrent/SettableFutureTest.java   |    4 -
 .../concurrent/SimpleTimeLimiterTest.java     |    1 -
 .../common/util/concurrent/StripedTest.java   |    6 +-
 .../concurrent/SupplementalMonitorTest.java   |    1 -
 .../concurrent/ThreadFactoryBuilderTest.java  |   10 -
 .../TrustedListenableFutureTaskTest.java      |    3 -
 .../UncaughtExceptionHandlersTest.java        |    1 -
 .../concurrent/UninterruptibleFutureTest.java |   11 -
 .../UninterruptibleMonitorTest.java           |    1 -
 .../util/concurrent/UninterruptiblesTest.java |    1 -
 guava/pom.xml                                 |   78 +-
 guava/src/com/google/common/base/Absent.java  |    7 +-
 .../google/common/base/AbstractIterator.java  |   15 +-
 guava/src/com/google/common/base/Ascii.java   |   19 +-
 .../com/google/common/base/CaseFormat.java    |   15 +-
 .../com/google/common/base/CharMatcher.java   |    7 +-
 .../src/com/google/common/base/Charsets.java  |    1 +
 .../com/google/common/base/CommonMatcher.java |    1 +
 .../com/google/common/base/CommonPattern.java |    1 +
 .../src/com/google/common/base/Converter.java |  157 ++-
 .../src/com/google/common/base/Defaults.java  |   47 +-
 .../base/ElementTypesAreNonnullByDefault.java |   41 +
 guava/src/com/google/common/base/Enums.java   |    8 +-
 .../com/google/common/base/Equivalence.java   |   84 +-
 .../base/ExtraObjectsMethodsForWeb.java       |    1 +
 .../base/FinalizablePhantomReference.java     |    4 +-
 .../common/base/FinalizableReference.java     |    1 +
 .../base/FinalizableReferenceQueue.java       |   16 +-
 .../common/base/FinalizableSoftReference.java |    4 +-
 .../common/base/FinalizableWeakReference.java |    4 +-
 .../src/com/google/common/base/Function.java  |   11 +-
 .../common/base/FunctionalEquivalence.java    |    9 +-
 .../src/com/google/common/base/Functions.java |  101 +-
 .../common/base/Java8Compatibility.java       |   44 +
 .../com/google/common/base/Java8Usage.java    |   45 -
 .../com/google/common/base/JdkPattern.java    |    1 +
 guava/src/com/google/common/base/Joiner.java  |   75 +-
 .../com/google/common/base/MoreObjects.java   |  125 +-
 .../com/google/common/base/NullnessCasts.java |   60 +
 guava/src/com/google/common/base/Objects.java |    6 +-
 .../src/com/google/common/base/Optional.java  |   28 +-
 .../common/base/PairwiseEquivalence.java      |   14 +-
 .../common/base/ParametricNullness.java       |   52 +
 .../google/common/base/PatternCompiler.java   |    1 +
 .../src/com/google/common/base/Platform.java  |   12 +-
 .../com/google/common/base/Preconditions.java |  309 +++--
 .../src/com/google/common/base/Predicate.java |   10 +-
 .../com/google/common/base/Predicates.java    |  137 +-
 guava/src/com/google/common/base/Present.java |    7 +-
 .../google/common/base/SmallCharMatcher.java  |    3 +-
 .../src/com/google/common/base/Splitter.java  |   12 +-
 .../common/base/StandardSystemProperty.java   |    6 +-
 .../src/com/google/common/base/Stopwatch.java |    3 +-
 guava/src/com/google/common/base/Strings.java |   20 +-
 .../src/com/google/common/base/Supplier.java  |    5 +-
 .../src/com/google/common/base/Suppliers.java |   87 +-
 .../com/google/common/base/Throwables.java    |   65 +-
 guava/src/com/google/common/base/Ticker.java  |    1 +
 guava/src/com/google/common/base/Utf8.java    |   10 +-
 guava/src/com/google/common/base/Verify.java  |  100 +-
 .../google/common/base/VerifyException.java   |    9 +-
 .../common/base/internal/Finalizer.java       |   21 +-
 .../google/common/cache/AbstractCache.java    |   10 +-
 .../common/cache/AbstractLoadingCache.java    |    1 +
 guava/src/com/google/common/cache/Cache.java  |   16 +-
 .../com/google/common/cache/CacheBuilder.java |   75 +-
 .../google/common/cache/CacheBuilderSpec.java |   63 +-
 .../com/google/common/cache/CacheLoader.java  |    1 +
 .../com/google/common/cache/CacheStats.java   |    5 +-
 .../ElementTypesAreNonnullByDefault.java      |   41 +
 .../google/common/cache/ForwardingCache.java  |   15 +-
 .../common/cache/ForwardingLoadingCache.java  |    1 +
 .../com/google/common/cache/LoadingCache.java |    3 +
 .../com/google/common/cache/LocalCache.java   |   22 +-
 .../com/google/common/cache/LongAddable.java  |    1 +
 .../com/google/common/cache/LongAddables.java |    4 +-
 .../com/google/common/cache/LongAdder.java    |    1 +
 .../common/cache/ParametricNullness.java      |   52 +
 .../google/common/cache/ReferenceEntry.java   |    8 +-
 .../com/google/common/cache/RemovalCause.java |    1 +
 .../google/common/cache/RemovalListener.java  |    1 +
 .../google/common/cache/RemovalListeners.java |   17 +-
 .../common/cache/RemovalNotification.java     |   11 +-
 .../com/google/common/cache/Striped64.java    |    8 +-
 .../src/com/google/common/cache/Weigher.java  |    1 +
 .../google/common/collect/AbstractBiMap.java  |  100 +-
 .../collect/AbstractIndexedListIterator.java  |    8 +-
 .../common/collect/AbstractIterator.java      |   17 +-
 .../common/collect/AbstractListMultimap.java  |   21 +-
 .../collect/AbstractMapBasedMultimap.java     |  274 ++--
 .../collect/AbstractMapBasedMultiset.java     |   42 +-
 .../common/collect/AbstractMapEntry.java      |   12 +-
 .../common/collect/AbstractMultimap.java      |   33 +-
 .../common/collect/AbstractMultiset.java      |   25 +-
 .../common/collect/AbstractNavigableMap.java  |   53 +-
 .../common/collect/AbstractRangeSet.java      |    6 +-
 .../collect/AbstractSequentialIterator.java   |   20 +-
 .../common/collect/AbstractSetMultimap.java   |   21 +-
 .../AbstractSortedKeySortedSetMultimap.java   |    6 +-
 .../collect/AbstractSortedMultiset.java       |   17 +-
 .../collect/AbstractSortedSetMultimap.java    |   17 +-
 .../google/common/collect/AbstractTable.java  |   37 +-
 .../common/collect/AllEqualOrdering.java      |   13 +-
 .../common/collect/ArrayListMultimap.java     |   15 +-
 .../com/google/common/collect/ArrayTable.java |  174 ++-
 .../common/collect/BaseImmutableMultimap.java |    1 +
 .../src/com/google/common/collect/BiMap.java  |   20 +-
 .../com/google/common/collect/BoundType.java  |    5 +-
 .../common/collect/ByFunctionOrdering.java    |    9 +-
 .../google/common/collect/CartesianList.java  |   13 +-
 .../common/collect/ClassToInstanceMap.java    |   23 +-
 .../common/collect/CollectCollectors.java     |  159 ++-
 .../common/collect/CollectPreconditions.java  |    1 +
 .../common/collect/CollectSpliterators.java   |  103 +-
 .../google/common/collect/Collections2.java   |   51 +-
 .../google/common/collect/CompactHashMap.java |  437 +++++--
 .../google/common/collect/CompactHashSet.java |  192 ++-
 .../google/common/collect/CompactHashing.java |   22 +-
 .../common/collect/CompactLinkedHashMap.java  |   69 +-
 .../common/collect/CompactLinkedHashSet.java  |   71 +-
 .../common/collect/ComparatorOrdering.java    |    9 +-
 .../google/common/collect/Comparators.java    |   39 +-
 .../common/collect/ComparisonChain.java       |   35 +-
 .../common/collect/CompoundOrdering.java      |    9 +-
 .../common/collect/ComputationException.java  |    4 +-
 .../collect/ConcurrentHashMultiset.java       |   42 +-
 .../collect/ConsumingQueueIterator.java       |   19 +-
 .../google/common/collect/ContiguousSet.java  |   24 +-
 .../src/com/google/common/collect/Count.java  |    5 +-
 guava/src/com/google/common/collect/Cut.java  |   39 +-
 .../common/collect/DenseImmutableTable.java   |   32 +-
 .../DescendingImmutableSortedMultiset.java    |    7 +-
 .../collect/DescendingImmutableSortedSet.java |   11 +-
 .../common/collect/DescendingMultiset.java    |   31 +-
 .../google/common/collect/DiscreteDomain.java |   20 +-
 .../ElementTypesAreNonnullByDefault.java      |   41 +
 .../common/collect/EmptyContiguousSet.java    |   13 +-
 .../collect/EmptyImmutableListMultimap.java   |    1 +
 .../collect/EmptyImmutableSetMultimap.java    |    1 +
 .../com/google/common/collect/EnumBiMap.java  |    3 +-
 .../google/common/collect/EnumHashBiMap.java  |   23 +-
 .../google/common/collect/EnumMultiset.java   |   19 +-
 .../google/common/collect/EvictingQueue.java  |   27 +-
 .../common/collect/ExplicitOrdering.java      |    4 +-
 .../common/collect/FilteredEntryMultimap.java |   48 +-
 .../collect/FilteredEntrySetMultimap.java     |   13 +-
 .../collect/FilteredKeyListMultimap.java      |   12 +-
 .../common/collect/FilteredKeyMultimap.java   |   39 +-
 .../collect/FilteredKeySetMultimap.java       |   14 +-
 .../common/collect/FilteredMultimap.java      |    5 +-
 .../collect/FilteredMultimapValues.java       |    9 +-
 .../common/collect/FilteredSetMultimap.java   |    5 +-
 .../google/common/collect/FluentIterable.java |   74 +-
 .../collect/ForwardingBlockingDeque.java      |    5 +
 .../common/collect/ForwardingCollection.java  |   30 +-
 .../collect/ForwardingConcurrentMap.java      |    9 +-
 .../common/collect/ForwardingDeque.java       |   29 +-
 .../ForwardingImmutableCollection.java        |    1 +
 .../collect/ForwardingImmutableList.java      |    1 +
 .../collect/ForwardingImmutableMap.java       |    1 +
 .../collect/ForwardingImmutableSet.java       |    1 +
 .../common/collect/ForwardingIterator.java    |    7 +-
 .../google/common/collect/ForwardingList.java |   29 +-
 .../collect/ForwardingListIterator.java       |   14 +-
 .../collect/ForwardingListMultimap.java       |   12 +-
 .../google/common/collect/ForwardingMap.java  |   39 +-
 .../common/collect/ForwardingMapEntry.java    |   15 +-
 .../common/collect/ForwardingMultimap.java    |   25 +-
 .../common/collect/ForwardingMultiset.java    |   31 +-
 .../collect/ForwardingNavigableMap.java       |   91 +-
 .../collect/ForwardingNavigableSet.java       |   58 +-
 .../common/collect/ForwardingObject.java      |    1 +
 .../common/collect/ForwardingQueue.java       |   16 +-
 .../google/common/collect/ForwardingSet.java  |    9 +-
 .../common/collect/ForwardingSetMultimap.java |   12 +-
 .../common/collect/ForwardingSortedMap.java   |   40 +-
 .../collect/ForwardingSortedMultiset.java     |   29 +-
 .../common/collect/ForwardingSortedSet.java   |   50 +-
 .../collect/ForwardingSortedSetMultimap.java  |   14 +-
 .../common/collect/ForwardingTable.java       |   31 +-
 .../google/common/collect/GeneralRange.java   |   93 +-
 .../google/common/collect/GwtTransient.java   |    1 +
 .../google/common/collect/HashBasedTable.java |   43 +-
 .../com/google/common/collect/HashBiMap.java  |  131 +-
 .../google/common/collect/HashMultimap.java   |   16 +-
 .../google/common/collect/HashMultiset.java   |   10 +-
 .../com/google/common/collect/Hashing.java    |    4 +-
 .../common/collect/ImmutableAsList.java       |    4 +-
 .../google/common/collect/ImmutableBiMap.java |  226 +++-
 .../collect/ImmutableBiMapFauxverideShim.java |   21 +-
 .../collect/ImmutableClassToInstanceMap.java  |   16 +-
 .../common/collect/ImmutableCollection.java   |   28 +-
 .../google/common/collect/ImmutableEntry.java |   19 +-
 .../common/collect/ImmutableEnumMap.java      |   10 +-
 .../common/collect/ImmutableEnumSet.java      |    6 +-
 .../google/common/collect/ImmutableList.java  |   67 +-
 .../common/collect/ImmutableListMultimap.java |   29 +-
 .../google/common/collect/ImmutableMap.java   |  444 +++++--
 .../common/collect/ImmutableMapEntry.java     |   36 +-
 .../common/collect/ImmutableMapEntrySet.java  |    8 +-
 .../common/collect/ImmutableMapKeySet.java    |    5 +-
 .../common/collect/ImmutableMapValues.java    |    5 +-
 .../common/collect/ImmutableMultimap.java     |   66 +-
 .../common/collect/ImmutableMultiset.java     |   52 +-
 ...eMultisetGwtSerializationDependencies.java |    1 +
 .../common/collect/ImmutableRangeMap.java     |   22 +-
 .../common/collect/ImmutableRangeSet.java     |   23 +-
 .../google/common/collect/ImmutableSet.java   |  385 ++++--
 .../common/collect/ImmutableSetMultimap.java  |   52 +-
 .../common/collect/ImmutableSortedAsList.java |   10 +-
 .../common/collect/ImmutableSortedMap.java    |  301 ++++-
 .../ImmutableSortedMapFauxverideShim.java     |  176 ++-
 .../collect/ImmutableSortedMultiset.java      |   29 +-
 ...ImmutableSortedMultisetFauxverideShim.java |   19 +-
 .../common/collect/ImmutableSortedSet.java    |   31 +-
 .../ImmutableSortedSetFauxverideShim.java     |   14 +-
 .../google/common/collect/ImmutableTable.java |   63 +-
 .../common/collect/IndexedImmutableSet.java   |    6 +-
 .../com/google/common/collect/Interner.java   |    3 +-
 .../com/google/common/collect/Interners.java  |   20 +-
 .../com/google/common/collect/Iterables.java  |  157 ++-
 .../com/google/common/collect/Iterators.java  |  254 ++--
 .../collect/JdkBackedImmutableBiMap.java      |   20 +-
 .../common/collect/JdkBackedImmutableMap.java |   56 +-
 .../collect/JdkBackedImmutableMultiset.java   |    9 +-
 .../common/collect/JdkBackedImmutableSet.java |    5 +-
 .../collect/LexicographicalOrdering.java      |    7 +-
 .../common/collect/LinkedHashMultimap.java    |  140 +-
 .../common/collect/LinkedHashMultiset.java    |   14 +-
 .../common/collect/LinkedListMultimap.java    |  181 +--
 .../google/common/collect/ListMultimap.java   |   16 +-
 .../src/com/google/common/collect/Lists.java  |  176 +--
 .../google/common/collect/MapDifference.java  |   12 +-
 .../com/google/common/collect/MapMaker.java   |    8 +-
 .../common/collect/MapMakerInternalMap.java   |    6 +-
 guava/src/com/google/common/collect/Maps.java | 1142 +++++++++++------
 .../common/collect/MinMaxPriorityQueue.java   |   53 +-
 .../google/common/collect/MoreCollectors.java |   36 +-
 .../com/google/common/collect/Multimap.java   |   29 +-
 .../common/collect/MultimapBuilder.java       |  104 +-
 .../com/google/common/collect/Multimaps.java  |  360 ++++--
 .../com/google/common/collect/Multiset.java   |   34 +-
 .../com/google/common/collect/Multisets.java  |  163 ++-
 .../collect/MutableClassToInstanceMap.java    |   26 +-
 .../common/collect/NaturalOrdering.java       |   30 +-
 .../google/common/collect/NullnessCasts.java  |   68 +
 .../common/collect/NullsFirstOrdering.java    |   20 +-
 .../common/collect/NullsLastOrdering.java     |   20 +-
 .../google/common/collect/ObjectArrays.java   |   23 +-
 .../com/google/common/collect/Ordering.java   |   48 +-
 .../common/collect/ParametricNullness.java    |   52 +
 .../common/collect/PeekingIterator.java       |    8 +-
 .../com/google/common/collect/Platform.java   |   42 +-
 .../src/com/google/common/collect/Queues.java |   18 +-
 .../src/com/google/common/collect/Range.java  |   26 +-
 .../com/google/common/collect/RangeMap.java   |   38 +-
 .../com/google/common/collect/RangeSet.java   |   10 +-
 .../common/collect/RegularContiguousSet.java  |   29 +-
 .../collect/RegularImmutableAsList.java       |    7 +-
 .../common/collect/RegularImmutableBiMap.java |   70 +-
 .../common/collect/RegularImmutableList.java  |    3 +-
 .../common/collect/RegularImmutableMap.java   |  181 ++-
 .../collect/RegularImmutableMultiset.java     |   56 +-
 .../common/collect/RegularImmutableSet.java   |   29 +-
 .../RegularImmutableSortedMultiset.java       |    7 +-
 .../collect/RegularImmutableSortedSet.java    |   15 +-
 .../common/collect/RegularImmutableTable.java |   38 +-
 .../collect/ReverseNaturalOrdering.java       |   25 +-
 .../common/collect/ReverseOrdering.java       |   19 +-
 .../google/common/collect/RowSortedTable.java |    6 +-
 .../google/common/collect/Serialization.java  |   35 +-
 .../google/common/collect/SetMultimap.java    |   19 +-
 guava/src/com/google/common/collect/Sets.java |  287 +++--
 .../collect/SingletonImmutableBiMap.java      |   14 +-
 .../collect/SingletonImmutableList.java       |    3 +-
 .../common/collect/SingletonImmutableSet.java |   39 +-
 .../collect/SingletonImmutableTable.java      |    1 +
 .../google/common/collect/SortedIterable.java |    4 +-
 .../common/collect/SortedIterables.java       |    5 +-
 .../google/common/collect/SortedLists.java    |   56 +-
 .../common/collect/SortedMapDifference.java   |    5 +-
 .../google/common/collect/SortedMultiset.java |   22 +-
 .../common/collect/SortedMultisetBridge.java  |    4 +-
 .../common/collect/SortedMultisets.java       |   53 +-
 .../common/collect/SortedSetMultimap.java     |   21 +-
 .../common/collect/SparseImmutableTable.java  |   20 +-
 .../collect/StandardRowSortedTable.java       |    3 +
 .../google/common/collect/StandardTable.java  |  198 ++-
 .../com/google/common/collect/Streams.java    |  140 +-
 .../google/common/collect/Synchronized.java   |  430 ++++---
 .../src/com/google/common/collect/Table.java  |   50 +-
 .../common/collect/TableCollectors.java       |   69 +-
 .../src/com/google/common/collect/Tables.java |  187 ++-
 .../google/common/collect/TopKSelector.java   |   44 +-
 .../common/collect/TransformedIterator.java   |    9 +-
 .../collect/TransformedListIterator.java      |   11 +-
 .../google/common/collect/TreeBasedTable.java |   73 +-
 .../google/common/collect/TreeMultimap.java   |   19 +-
 .../google/common/collect/TreeMultiset.java   |  240 ++--
 .../google/common/collect/TreeRangeMap.java   |   90 +-
 .../google/common/collect/TreeRangeSet.java   |   79 +-
 .../google/common/collect/TreeTraverser.java  |    3 +
 .../common/collect/UnmodifiableIterator.java  |    4 +-
 .../collect/UnmodifiableListIterator.java     |   10 +-
 .../collect/UnmodifiableSortedMultiset.java   |   21 +-
 .../common/collect/UsingToStringOrdering.java |    1 +
 .../common/escape/ArrayBasedCharEscaper.java  |    9 +-
 .../common/escape/ArrayBasedEscaperMap.java   |   11 +-
 .../escape/ArrayBasedUnicodeEscaper.java      |    8 +-
 .../com/google/common/escape/CharEscaper.java |   18 +-
 .../common/escape/CharEscaperBuilder.java     |   17 +-
 .../ElementTypesAreNonnullByDefault.java      |   41 +
 .../src/com/google/common/escape/Escaper.java |    9 +-
 .../com/google/common/escape/Escapers.java    |   18 +-
 .../common/escape/ParametricNullness.java     |   52 +
 .../com/google/common/escape/Platform.java    |    1 +
 .../google/common/escape/UnicodeEscaper.java  |    5 +-
 .../eventbus/AllowConcurrentEvents.java       |    3 +-
 .../google/common/eventbus/AsyncEventBus.java |    3 +-
 .../com/google/common/eventbus/DeadEvent.java |    3 +-
 .../google/common/eventbus/Dispatcher.java    |    1 +
 .../ElementTypesAreNonnullByDefault.java      |   41 +
 .../com/google/common/eventbus/EventBus.java  |   61 +-
 .../common/eventbus/ParametricNullness.java   |   52 +
 .../com/google/common/eventbus/Subscribe.java |    3 +-
 .../google/common/eventbus/Subscriber.java    |   20 +-
 .../eventbus/SubscriberExceptionContext.java  |    5 +-
 .../eventbus/SubscriberExceptionHandler.java  |    2 +
 .../common/eventbus/SubscriberRegistry.java   |    5 +-
 .../common/graph/AbstractBaseGraph.java       |   29 +-
 .../AbstractDirectedNetworkConnections.java   |   22 +-
 .../google/common/graph/AbstractGraph.java    |    5 +-
 .../common/graph/AbstractGraphBuilder.java    |    1 +
 .../google/common/graph/AbstractNetwork.java  |   13 +-
 .../AbstractUndirectedNetworkConnections.java |   14 +-
 .../common/graph/AbstractValueGraph.java      |   10 +-
 .../com/google/common/graph/BaseGraph.java    |    1 +
 .../graph/DirectedGraphConnections.java       |   91 +-
 .../DirectedMultiNetworkConnections.java      |   12 +-
 .../graph/DirectedNetworkConnections.java     |    6 +-
 .../google/common/graph/EdgesConnecting.java  |    8 +-
 .../com/google/common/graph/ElementOrder.java |   20 +-
 .../ElementTypesAreNonnullByDefault.java      |   41 +
 .../com/google/common/graph/EndpointPair.java |   16 +-
 .../common/graph/EndpointPairIterator.java    |   30 +-
 .../google/common/graph/ForwardingGraph.java  |    3 +-
 .../common/graph/ForwardingNetwork.java       |    6 +-
 .../common/graph/ForwardingValueGraph.java    |   11 +-
 guava/src/com/google/common/graph/Graph.java  |    5 +-
 .../com/google/common/graph/GraphBuilder.java |    3 +-
 .../google/common/graph/GraphConnections.java |    7 +-
 .../google/common/graph/GraphConstants.java   |   10 +-
 guava/src/com/google/common/graph/Graphs.java |   35 +-
 .../google/common/graph/ImmutableGraph.java   |    5 +-
 .../google/common/graph/ImmutableNetwork.java |   34 +-
 .../common/graph/ImmutableValueGraph.java     |   18 +-
 .../google/common/graph/IncidentEdgeSet.java  |   11 +-
 .../google/common/graph/MapIteratorCache.java |   46 +-
 .../common/graph/MapRetrievalCache.java       |   22 +-
 .../common/graph/MultiEdgesConnecting.java    |    8 +-
 .../com/google/common/graph/MutableGraph.java |    1 +
 .../google/common/graph/MutableNetwork.java   |    1 +
 .../common/graph/MutableValueGraph.java       |    6 +
 .../src/com/google/common/graph/Network.java  |    9 +-
 .../google/common/graph/NetworkBuilder.java   |    1 +
 .../common/graph/NetworkConnections.java      |    3 +
 .../common/graph/ParametricNullness.java      |   52 +
 .../common/graph/PredecessorsFunction.java    |    1 +
 .../common/graph/StandardMutableGraph.java    |    3 +-
 .../common/graph/StandardMutableNetwork.java  |    7 +-
 .../graph/StandardMutableValueGraph.java      |   15 +-
 .../google/common/graph/StandardNetwork.java  |   18 +-
 .../common/graph/StandardValueGraph.java      |   39 +-
 .../common/graph/SuccessorsFunction.java      |    1 +
 .../com/google/common/graph/Traverser.java    |   48 +-
 .../graph/UndirectedGraphConnections.java     |   15 +-
 .../UndirectedMultiNetworkConnections.java    |   11 +-
 .../graph/UndirectedNetworkConnections.java   |    5 +-
 .../com/google/common/graph/ValueGraph.java   |   13 +-
 .../common/graph/ValueGraphBuilder.java       |    1 +
 .../common/hash/AbstractByteHasher.java       |    7 +-
 .../hash/AbstractCompositeHashFunction.java   |    7 +-
 .../common/hash/AbstractHashFunction.java     |   10 +-
 .../google/common/hash/AbstractHasher.java    |    5 +-
 .../AbstractNonStreamingHashFunction.java     |   14 +-
 .../common/hash/AbstractStreamingHasher.java  |    1 +
 .../com/google/common/hash/BloomFilter.java   |   69 +-
 .../common/hash/BloomFilterStrategies.java    |   83 +-
 .../common/hash/ChecksumHashFunction.java     |    1 +
 .../common/hash/Crc32cHashFunction.java       |    1 +
 .../hash/ElementTypesAreNonnullByDefault.java |   41 +
 .../common/hash/FarmHashFingerprint64.java    |    3 +-
 .../google/common/hash/Fingerprint2011.java   |  198 +++
 guava/src/com/google/common/hash/Funnel.java  |    6 +-
 guava/src/com/google/common/hash/Funnels.java |   16 +-
 .../src/com/google/common/hash/HashCode.java  |   18 +-
 .../com/google/common/hash/HashFunction.java  |    7 +-
 guava/src/com/google/common/hash/Hasher.java  |    5 +-
 guava/src/com/google/common/hash/Hashing.java |   89 +-
 .../common/hash/HashingInputStream.java       |   12 +-
 .../common/hash/HashingOutputStream.java      |    1 +
 .../google/common/hash/ImmutableSupplier.java |    2 +
 .../common/hash/Java8Compatibility.java       |    1 +
 .../common/hash/LittleEndianByteArray.java    |    6 +-
 .../com/google/common/hash/LongAddable.java   |    2 +
 .../com/google/common/hash/LongAddables.java  |    4 +-
 .../src/com/google/common/hash/LongAdder.java |    1 +
 .../google/common/hash/MacHashFunction.java   |    7 +-
 .../hash/MessageDigestHashFunction.java       |    5 +-
 .../common/hash/Murmur3_128HashFunction.java  |    6 +-
 .../common/hash/Murmur3_32HashFunction.java   |   34 +-
 .../common/hash/ParametricNullness.java       |   52 +
 .../com/google/common/hash/PrimitiveSink.java |    1 +
 .../google/common/hash/SipHashFunction.java   |    4 +-
 .../src/com/google/common/hash/Striped64.java |   17 +-
 .../html/ElementTypesAreNonnullByDefault.java |   41 +
 .../com/google/common/html/HtmlEscapers.java  |    1 +
 .../common/html/ParametricNullness.java       |   52 +
 .../google/common/io/AppendableWriter.java    |   12 +-
 .../com/google/common/io/BaseEncoding.java    |   56 +-
 .../google/common/io/ByteArrayDataInput.java  |    3 +
 .../google/common/io/ByteArrayDataOutput.java |    1 +
 .../com/google/common/io/ByteProcessor.java   |    5 +-
 guava/src/com/google/common/io/ByteSink.java  |    1 +
 .../src/com/google/common/io/ByteSource.java  |   21 +-
 .../src/com/google/common/io/ByteStreams.java |   45 +-
 .../google/common/io/CharSequenceReader.java  |   29 +-
 guava/src/com/google/common/io/CharSink.java  |    1 +
 .../src/com/google/common/io/CharSource.java  |   25 +-
 .../src/com/google/common/io/CharStreams.java |   12 +-
 .../src/com/google/common/io/Closeables.java  |    9 +-
 guava/src/com/google/common/io/Closer.java    |   39 +-
 .../google/common/io/CountingInputStream.java |    1 +
 .../common/io/CountingOutputStream.java       |    1 +
 .../io/ElementTypesAreNonnullByDefault.java   |   41 +
 .../common/io/FileBackedOutputStream.java     |   31 +-
 .../com/google/common/io/FileWriteMode.java   |    1 +
 guava/src/com/google/common/io/Files.java     |   85 +-
 .../src/com/google/common/io/Flushables.java  |    1 +
 .../io/InsecureRecursiveDeleteException.java  |    5 +-
 .../google/common/io/Java8Compatibility.java  |    9 +
 .../src/com/google/common/io/LineBuffer.java  |   15 +-
 .../com/google/common/io/LineProcessor.java   |    5 +-
 .../src/com/google/common/io/LineReader.java  |    8 +-
 .../io/LittleEndianDataInputStream.java       |    3 +-
 .../io/LittleEndianDataOutputStream.java      |    1 +
 guava/src/com/google/common/io/MoreFiles.java |   96 +-
 .../google/common/io/MultiInputStream.java    |    7 +-
 .../src/com/google/common/io/MultiReader.java |    9 +-
 .../google/common/io/ParametricNullness.java  |   52 +
 .../common/io/PatternFilenameFilter.java      |   17 +-
 .../google/common/io/ReaderInputStream.java   |    5 +-
 .../common/io/RecursiveDeleteOption.java      |    1 +
 guava/src/com/google/common/io/Resources.java |   11 +-
 .../google/common/math/BigDecimalMath.java    |    1 +
 .../google/common/math/BigIntegerMath.java    |   11 +-
 .../com/google/common/math/DoubleMath.java    |    3 +-
 .../com/google/common/math/DoubleUtils.java   |    1 +
 .../math/ElementTypesAreNonnullByDefault.java |   41 +
 guava/src/com/google/common/math/IntMath.java |    5 +-
 .../common/math/LinearTransformation.java     |    6 +-
 .../src/com/google/common/math/LongMath.java  |   11 +-
 .../google/common/math/MathPreconditions.java |   16 +-
 .../com/google/common/math/PairedStats.java   |    5 +-
 .../common/math/PairedStatsAccumulator.java   |    1 +
 .../common/math/ParametricNullness.java       |   52 +
 .../src/com/google/common/math/Quantiles.java |    1 +
 guava/src/com/google/common/math/Stats.java   |    4 +-
 .../google/common/math/StatsAccumulator.java  |    1 +
 .../google/common/math/ToDoubleRounder.java   |    1 +
 .../net/ElementTypesAreNonnullByDefault.java  |   41 +
 .../com/google/common/net/HostAndPort.java    |   22 +-
 .../com/google/common/net/HostSpecifier.java  |   19 +-
 .../com/google/common/net/HttpHeaders.java    |  187 ++-
 .../com/google/common/net/InetAddresses.java  |   73 +-
 .../google/common/net/InternetDomainName.java |   17 +-
 .../src/com/google/common/net/MediaType.java  |   38 +-
 .../google/common/net/ParametricNullness.java |   52 +
 .../com/google/common/net/PercentEscaper.java |    5 +-
 .../com/google/common/net/UrlEscapers.java    |    1 +
 .../com/google/common/net/package-info.java   |    2 +
 .../google/common/primitives/Booleans.java    |   23 +-
 .../com/google/common/primitives/Bytes.java   |   20 +-
 .../com/google/common/primitives/Chars.java   |   20 +-
 .../com/google/common/primitives/Doubles.java |   23 +-
 .../primitives/DoublesMethodsForWeb.java      |    1 +
 .../ElementTypesAreNonnullByDefault.java      |   41 +
 .../com/google/common/primitives/Floats.java  |   23 +-
 .../primitives/FloatsMethodsForWeb.java       |    1 +
 .../primitives/ImmutableDoubleArray.java      |   23 +-
 .../common/primitives/ImmutableIntArray.java  |   23 +-
 .../common/primitives/ImmutableLongArray.java |   23 +-
 .../com/google/common/primitives/Ints.java    |   23 +-
 .../common/primitives/IntsMethodsForWeb.java  |    1 +
 .../com/google/common/primitives/Longs.java   |   21 +-
 .../common/primitives/ParametricNullness.java |   52 +
 .../common/primitives/ParseRequest.java       |    1 +
 .../google/common/primitives/Platform.java    |    1 +
 .../google/common/primitives/Primitives.java  |    1 +
 .../com/google/common/primitives/Shorts.java  |   20 +-
 .../primitives/ShortsMethodsForWeb.java       |    1 +
 .../google/common/primitives/SignedBytes.java |    1 +
 .../common/primitives/UnsignedBytes.java      |    9 +-
 .../common/primitives/UnsignedInteger.java    |    6 +-
 .../common/primitives/UnsignedInts.java       |    1 +
 .../common/primitives/UnsignedLong.java       |   26 +-
 .../common/primitives/UnsignedLongs.java      |    1 +
 .../reflect/AbstractInvocationHandler.java    |   12 +-
 .../com/google/common/reflect/ClassPath.java  |   67 +-
 .../com/google/common/reflect/Element.java    |  178 ---
 .../ElementTypesAreNonnullByDefault.java      |   41 +
 .../reflect/ImmutableTypeToInstanceMap.java   |   17 +-
 .../com/google/common/reflect/Invokable.java  |  184 ++-
 .../reflect/MutableTypeToInstanceMap.java     |   51 +-
 .../com/google/common/reflect/Parameter.java  |   20 +-
 .../common/reflect/ParametricNullness.java    |   52 +
 .../com/google/common/reflect/Reflection.java |    3 +-
 .../google/common/reflect/TypeCapture.java    |    1 +
 .../google/common/reflect/TypeParameter.java  |   17 +-
 .../google/common/reflect/TypeResolver.java   |   25 +-
 .../common/reflect/TypeToInstanceMap.java     |   20 +-
 .../com/google/common/reflect/TypeToken.java  |   98 +-
 .../google/common/reflect/TypeVisitor.java    |    4 +-
 .../src/com/google/common/reflect/Types.java  |   61 +-
 .../concurrent/AbstractCatchingFuture.java    |   37 +-
 .../AbstractExecutionThreadService.java       |    1 +
 .../util/concurrent/AbstractFuture.java       |  244 +++-
 .../util/concurrent/AbstractIdleService.java  |    1 +
 .../AbstractListeningExecutorService.java     |   11 +-
 .../concurrent/AbstractScheduledService.java  |  188 ++-
 .../util/concurrent/AbstractService.java      |   15 +-
 .../concurrent/AbstractTransformFuture.java   |   36 +-
 .../util/concurrent/AggregateFuture.java      |  101 +-
 .../util/concurrent/AggregateFutureState.java |   41 +-
 .../common/util/concurrent/AsyncCallable.java |    6 +-
 .../common/util/concurrent/AsyncFunction.java |    5 +-
 .../common/util/concurrent/AtomicDouble.java  |   68 +-
 .../util/concurrent/AtomicDoubleArray.java    |   80 +-
 .../common/util/concurrent/AtomicLongMap.java |    5 +-
 .../common/util/concurrent/Atomics.java       |   18 +-
 .../common/util/concurrent/Callables.java     |   71 +-
 .../common/util/concurrent/ClosingFuture.java |  173 ++-
 .../util/concurrent/CollectionFuture.java     |   32 +-
 .../util/concurrent/CombinedFuture.java       |   45 +-
 .../concurrent/CycleDetectingLockFactory.java |   40 +-
 .../util/concurrent/DirectExecutor.java       |    1 +
 .../ElementTypesAreNonnullByDefault.java      |   41 +
 .../util/concurrent/ExecutionError.java       |   15 +-
 .../common/util/concurrent/ExecutionList.java |   11 +-
 .../util/concurrent/ExecutionSequencer.java   |  168 ++-
 .../util/concurrent/FakeTimeLimiter.java      |   10 +-
 .../common/util/concurrent/FluentFuture.java  |   25 +-
 .../concurrent/ForwardingBlockingDeque.java   |    5 +
 .../concurrent/ForwardingBlockingQueue.java   |    3 +
 .../util/concurrent/ForwardingCondition.java  |    1 +
 .../concurrent/ForwardingExecutorService.java |   18 +-
 .../concurrent/ForwardingFluentFuture.java    |    6 +-
 .../util/concurrent/ForwardingFuture.java     |   10 +-
 .../ForwardingListenableFuture.java           |    8 +-
 .../ForwardingListeningExecutorService.java   |    7 +-
 .../util/concurrent/ForwardingLock.java       |    1 +
 .../util/concurrent/FutureCallback.java       |    5 +-
 .../common/util/concurrent/Futures.java       |  215 ++--
 .../util/concurrent/FuturesGetChecked.java    |   21 +-
 ...GwtFluentFutureCatchingSpecialization.java |    5 +-
 .../GwtFuturesCatchingSpecialization.java     |    1 +
 .../util/concurrent/IgnoreJRERequirement.java |   24 -
 .../util/concurrent/ImmediateFuture.java      |   18 +-
 .../common/util/concurrent/Internal.java      |    1 +
 .../util/concurrent/InterruptibleTask.java    |  201 ++-
 .../util/concurrent/JdkFutureAdapters.java    |   43 +-
 .../util/concurrent/ListenableFuture.java     |   19 +-
 .../util/concurrent/ListenableFutureTask.java |   16 +-
 .../concurrent/ListenableScheduledFuture.java |    7 +-
 .../util/concurrent/ListenerCallQueue.java    |    3 +-
 .../concurrent/ListeningExecutorService.java  |   11 +-
 .../ListeningScheduledExecutorService.java    |    8 +-
 .../common/util/concurrent/Monitor.java       |   17 +-
 .../common/util/concurrent/MoreExecutors.java |   85 +-
 .../common/util/concurrent/NullnessCasts.java |   76 ++
 .../OverflowAvoidingLockSupport.java          |    5 +-
 .../util/concurrent/ParametricNullness.java   |   52 +
 .../common/util/concurrent/Partially.java     |    1 +
 .../common/util/concurrent/Platform.java      |    5 +-
 .../common/util/concurrent/RateLimiter.java   |    5 +-
 .../common/util/concurrent/Runnables.java     |    1 +
 .../util/concurrent/SequentialExecutor.java   |   10 +-
 .../common/util/concurrent/Service.java       |   46 +-
 .../util/concurrent/ServiceManager.java       |   25 +-
 .../util/concurrent/ServiceManagerBridge.java |    1 +
 .../util/concurrent/SettableFuture.java       |   10 +-
 .../util/concurrent/SimpleTimeLimiter.java    |   35 +-
 .../util/concurrent/SmoothRateLimiter.java    |    1 +
 .../common/util/concurrent/Striped.java       |   98 +-
 .../util/concurrent/ThreadFactoryBuilder.java |   34 +-
 .../common/util/concurrent/TimeLimiter.java   |   13 +-
 .../common/util/concurrent/TimeoutFuture.java |   17 +-
 .../TrustedListenableFutureTask.java          |   54 +-
 .../concurrent/UncaughtExceptionHandlers.java |    1 +
 .../UncheckedExecutionException.java          |   15 +-
 .../concurrent/UncheckedTimeoutException.java |    9 +-
 .../util/concurrent/Uninterruptibles.java     |   28 +-
 .../concurrent/WrappingExecutorService.java   |   40 +-
 .../WrappingScheduledExecutorService.java     |    5 +-
 .../xml/ElementTypesAreNonnullByDefault.java  |   41 +
 .../google/common/xml/ParametricNullness.java |   52 +
 .../com/google/common/xml/XmlEscapers.java    |    3 +-
 .../publicsuffix/PublicSuffixPatterns.java    |    6 +-
 .../thirdparty/publicsuffix/TrieParser.java   |    2 +-
 pom.xml                                       |   98 +-
 1638 files changed, 37236 insertions(+), 18409 deletions(-)
 create mode 100644 .github/dependabot.yml
 create mode 100644 android/guava-tests/test/com/google/common/eventbus/outside/AbstractEventBusTest.java
 create mode 100644 android/guava-tests/test/com/google/common/eventbus/outside/AbstractNotAnnotatedInSuperclassTest.java
 create mode 100644 android/guava-tests/test/com/google/common/eventbus/outside/AnnotatedAndAbstractInSuperclassTest.java
 create mode 100644 android/guava-tests/test/com/google/common/eventbus/outside/AnnotatedNotAbstractInSuperclassTest.java
 delete mode 100644 android/guava-tests/test/com/google/common/eventbus/outside/AnnotatedSubscriberFinderTests.java
 create mode 100644 android/guava-tests/test/com/google/common/eventbus/outside/BaseSubscriberFinderTest.java
 create mode 100644 android/guava-tests/test/com/google/common/eventbus/outside/DeepInterfaceTest.java
 create mode 100644 android/guava-tests/test/com/google/common/eventbus/outside/NeitherAbstractNorAnnotatedInSuperclassTest.java
 create mode 100644 android/guava-tests/test/com/google/common/hash/Fingerprint2011Test.java
 delete mode 100644 android/guava-tests/test/com/google/common/reflect/ElementTest.java
 rename android/guava-tests/test/com/google/common/util/concurrent/{ClosingFutureTest.java => AbstractClosingFutureTest.java} (91%)
 create mode 100644 android/guava-tests/test/com/google/common/util/concurrent/ClosingFutureFinishToFutureTest.java
 create mode 100644 android/guava-tests/test/com/google/common/util/concurrent/ClosingFutureFinishToValueAndCloserTest.java
 create mode 100644 android/guava/src/com/google/common/base/ElementTypesAreNonnullByDefault.java
 create mode 100644 android/guava/src/com/google/common/base/Java8Compatibility.java
 delete mode 100755 android/guava/src/com/google/common/base/Java8Usage.java
 create mode 100644 android/guava/src/com/google/common/base/NullnessCasts.java
 create mode 100644 android/guava/src/com/google/common/base/ParametricNullness.java
 create mode 100644 android/guava/src/com/google/common/cache/ElementTypesAreNonnullByDefault.java
 create mode 100644 android/guava/src/com/google/common/cache/ParametricNullness.java
 create mode 100644 android/guava/src/com/google/common/collect/ElementTypesAreNonnullByDefault.java
 create mode 100644 android/guava/src/com/google/common/collect/NullnessCasts.java
 create mode 100644 android/guava/src/com/google/common/collect/ParametricNullness.java
 create mode 100644 android/guava/src/com/google/common/escape/ElementTypesAreNonnullByDefault.java
 create mode 100644 android/guava/src/com/google/common/escape/ParametricNullness.java
 create mode 100644 android/guava/src/com/google/common/eventbus/ElementTypesAreNonnullByDefault.java
 create mode 100644 android/guava/src/com/google/common/eventbus/ParametricNullness.java
 create mode 100644 android/guava/src/com/google/common/graph/ElementTypesAreNonnullByDefault.java
 create mode 100644 android/guava/src/com/google/common/graph/ParametricNullness.java
 create mode 100644 android/guava/src/com/google/common/hash/ElementTypesAreNonnullByDefault.java
 create mode 100644 android/guava/src/com/google/common/hash/Fingerprint2011.java
 create mode 100644 android/guava/src/com/google/common/hash/ParametricNullness.java
 create mode 100644 android/guava/src/com/google/common/html/ElementTypesAreNonnullByDefault.java
 create mode 100644 android/guava/src/com/google/common/html/ParametricNullness.java
 create mode 100644 android/guava/src/com/google/common/io/ElementTypesAreNonnullByDefault.java
 create mode 100644 android/guava/src/com/google/common/io/ParametricNullness.java
 create mode 100644 android/guava/src/com/google/common/math/ElementTypesAreNonnullByDefault.java
 create mode 100644 android/guava/src/com/google/common/math/ParametricNullness.java
 create mode 100644 android/guava/src/com/google/common/net/ElementTypesAreNonnullByDefault.java
 create mode 100644 android/guava/src/com/google/common/net/ParametricNullness.java
 create mode 100644 android/guava/src/com/google/common/primitives/ElementTypesAreNonnullByDefault.java
 create mode 100644 android/guava/src/com/google/common/primitives/ParametricNullness.java
 delete mode 100644 android/guava/src/com/google/common/reflect/Element.java
 create mode 100644 android/guava/src/com/google/common/reflect/ElementTypesAreNonnullByDefault.java
 create mode 100644 android/guava/src/com/google/common/reflect/ParametricNullness.java
 create mode 100644 android/guava/src/com/google/common/util/concurrent/ElementTypesAreNonnullByDefault.java
 create mode 100644 android/guava/src/com/google/common/util/concurrent/NullnessCasts.java
 create mode 100644 android/guava/src/com/google/common/util/concurrent/ParametricNullness.java
 create mode 100644 android/guava/src/com/google/common/xml/ElementTypesAreNonnullByDefault.java
 create mode 100644 android/guava/src/com/google/common/xml/ParametricNullness.java
 create mode 100644 guava-tests/test/com/google/common/base/StopwatchJavaTimeTest.java
 create mode 100644 guava-tests/test/com/google/common/collect/CompactHashMapFloodingTest.java
 create mode 100644 guava-tests/test/com/google/common/collect/CompactHashSetFloodingTest.java
 rename android/guava/src/com/google/common/util/concurrent/IgnoreJRERequirement.java => guava-tests/test/com/google/common/collect/CompactLinkedHashMapFloodingTest.java (56%)
 create mode 100644 guava-tests/test/com/google/common/collect/CompactLinkedHashSetFloodingTest.java
 create mode 100644 guava-tests/test/com/google/common/eventbus/outside/AbstractEventBusTest.java
 create mode 100644 guava-tests/test/com/google/common/eventbus/outside/AbstractNotAnnotatedInSuperclassTest.java
 create mode 100644 guava-tests/test/com/google/common/eventbus/outside/AnnotatedAndAbstractInSuperclassTest.java
 create mode 100644 guava-tests/test/com/google/common/eventbus/outside/AnnotatedNotAbstractInSuperclassTest.java
 delete mode 100644 guava-tests/test/com/google/common/eventbus/outside/AnnotatedSubscriberFinderTests.java
 create mode 100644 guava-tests/test/com/google/common/eventbus/outside/BaseSubscriberFinderTest.java
 create mode 100644 guava-tests/test/com/google/common/eventbus/outside/DeepInterfaceTest.java
 create mode 100644 guava-tests/test/com/google/common/eventbus/outside/NeitherAbstractNorAnnotatedInSuperclassTest.java
 create mode 100644 guava-tests/test/com/google/common/hash/Fingerprint2011Test.java
 delete mode 100644 guava-tests/test/com/google/common/reflect/ElementTest.java
 rename guava-tests/test/com/google/common/util/concurrent/{ClosingFutureTest.java => AbstractClosingFutureTest.java} (91%)
 create mode 100644 guava-tests/test/com/google/common/util/concurrent/ClosingFutureFinishToFutureTest.java
 create mode 100644 guava-tests/test/com/google/common/util/concurrent/ClosingFutureFinishToValueAndCloserTest.java
 create mode 100644 guava/src/com/google/common/base/ElementTypesAreNonnullByDefault.java
 create mode 100644 guava/src/com/google/common/base/Java8Compatibility.java
 delete mode 100644 guava/src/com/google/common/base/Java8Usage.java
 create mode 100644 guava/src/com/google/common/base/NullnessCasts.java
 create mode 100644 guava/src/com/google/common/base/ParametricNullness.java
 create mode 100644 guava/src/com/google/common/cache/ElementTypesAreNonnullByDefault.java
 create mode 100644 guava/src/com/google/common/cache/ParametricNullness.java
 create mode 100644 guava/src/com/google/common/collect/ElementTypesAreNonnullByDefault.java
 create mode 100644 guava/src/com/google/common/collect/NullnessCasts.java
 create mode 100644 guava/src/com/google/common/collect/ParametricNullness.java
 create mode 100644 guava/src/com/google/common/escape/ElementTypesAreNonnullByDefault.java
 create mode 100644 guava/src/com/google/common/escape/ParametricNullness.java
 create mode 100644 guava/src/com/google/common/eventbus/ElementTypesAreNonnullByDefault.java
 create mode 100644 guava/src/com/google/common/eventbus/ParametricNullness.java
 create mode 100644 guava/src/com/google/common/graph/ElementTypesAreNonnullByDefault.java
 create mode 100644 guava/src/com/google/common/graph/ParametricNullness.java
 create mode 100644 guava/src/com/google/common/hash/ElementTypesAreNonnullByDefault.java
 create mode 100644 guava/src/com/google/common/hash/Fingerprint2011.java
 create mode 100644 guava/src/com/google/common/hash/ParametricNullness.java
 create mode 100644 guava/src/com/google/common/html/ElementTypesAreNonnullByDefault.java
 create mode 100644 guava/src/com/google/common/html/ParametricNullness.java
 create mode 100644 guava/src/com/google/common/io/ElementTypesAreNonnullByDefault.java
 create mode 100644 guava/src/com/google/common/io/ParametricNullness.java
 create mode 100644 guava/src/com/google/common/math/ElementTypesAreNonnullByDefault.java
 create mode 100644 guava/src/com/google/common/math/ParametricNullness.java
 create mode 100644 guava/src/com/google/common/net/ElementTypesAreNonnullByDefault.java
 create mode 100644 guava/src/com/google/common/net/ParametricNullness.java
 create mode 100644 guava/src/com/google/common/primitives/ElementTypesAreNonnullByDefault.java
 create mode 100644 guava/src/com/google/common/primitives/ParametricNullness.java
 delete mode 100644 guava/src/com/google/common/reflect/Element.java
 create mode 100644 guava/src/com/google/common/reflect/ElementTypesAreNonnullByDefault.java
 create mode 100644 guava/src/com/google/common/reflect/ParametricNullness.java
 create mode 100644 guava/src/com/google/common/util/concurrent/ElementTypesAreNonnullByDefault.java
 delete mode 100644 guava/src/com/google/common/util/concurrent/IgnoreJRERequirement.java
 create mode 100644 guava/src/com/google/common/util/concurrent/NullnessCasts.java
 create mode 100644 guava/src/com/google/common/util/concurrent/ParametricNullness.java
 create mode 100644 guava/src/com/google/common/xml/ElementTypesAreNonnullByDefault.java
 create mode 100644 guava/src/com/google/common/xml/ParametricNullness.java

diff --git a/.github/dependabot.yml b/.github/dependabot.yml
new file mode 100644
index 000000000000..1e956d2faa00
--- /dev/null
+++ b/.github/dependabot.yml
@@ -0,0 +1,16 @@
+version: 2
+updates:
+# TODO(b/170636568): Enable Maven updates? Perhaps wait until we can more
+# easily import the generated PRs into our internal repo.
+#  - package-ecosystem: "maven"
+#    directory: "/"
+#    schedule:
+#      interval: "daily"
+#  - package-ecosystem: "maven"
+#    directory: "/android"
+#    schedule:
+#      interval: "daily"
+  - package-ecosystem: "github-actions"
+    directory: "/"
+    schedule:
+      interval: "daily"
diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
index f3e07268881d..e0907fc21b4e 100644
--- a/.github/workflows/ci.yml
+++ b/.github/workflows/ci.yml
@@ -13,28 +13,34 @@ jobs:
     name: "${{ matrix.root-pom }} on JDK ${{ matrix.java }}"
     strategy:
       matrix:
-        java: [ 8, 11 ]
+        java: [ 11, 17 ]
         root-pom: [ 'pom.xml', 'android/pom.xml' ]
     runs-on: ubuntu-latest
     env:
       ROOT_POM: ${{ matrix.root-pom }}
     steps:
+      # Cancel any previous runs for the same branch that are still running.
+      - name: 'Cancel previous runs'
+        uses: styfle/cancel-workflow-action@0.9.1
+        with:
+          access_token: ${{ github.token }}
       - name: 'Check out repository'
-        uses: actions/checkout@v2
+        uses: actions/checkout@v2.4.0
       - name: 'Cache local Maven repository'
-        uses: actions/cache@v2.1.4
+        uses: actions/cache@v2.1.7
         with:
           path: ~/.m2/repository
           key: maven-${{ hashFiles('**/pom.xml') }}
           restore-keys: |
             maven-
       - name: 'Set up JDK ${{ matrix.java }}'
-        uses: actions/setup-java@v1
+        uses: actions/setup-java@v2
         with:
           java-version: ${{ matrix.java }}
+          distribution: 'zulu'
       - name: 'Install'
         shell: bash
-        run: mvn -B -Dorg.slf4j.simpleLogger.log.org.apache.maven.cli.transfer.Slf4jMavenTransferListener=warn install -U -DskipTests=true -f $ROOT_POM
+        run: mvn -B -Dorg.slf4j.simpleLogger.log.org.apache.maven.cli.transfer.Slf4jMavenTransferListener=warn install -U -Dmaven.test.skip -Dmaven.javadoc.skip -f $ROOT_POM
       - name: 'Test'
         shell: bash
         run: MAVEN_OPTS=-Xmx6g mvn -B -P!standard-with-extra-repos verify -U -Dmaven.javadoc.skip=true -f $ROOT_POM
@@ -51,18 +57,19 @@ jobs:
     runs-on: ubuntu-latest
     steps:
       - name: 'Check out repository'
-        uses: actions/checkout@v2
+        uses: actions/checkout@v2.4.0
       - name: 'Cache local Maven repository'
-        uses: actions/cache@v2.1.4
+        uses: actions/cache@v2.1.7
         with:
           path: ~/.m2/repository
           key: maven-${{ hashFiles('**/pom.xml') }}
           restore-keys: |
             maven-
       - name: 'Set up JDK 11'
-        uses: actions/setup-java@v1
+        uses: actions/setup-java@v2
         with:
           java-version: 11
+          distribution: 'zulu'
           server-id: sonatype-nexus-snapshots
           server-username: CI_DEPLOY_USERNAME
           server-password: CI_DEPLOY_PASSWORD
@@ -79,18 +86,19 @@ jobs:
     runs-on: ubuntu-latest
     steps:
       - name: 'Check out repository'
-        uses: actions/checkout@v2
+        uses: actions/checkout@v2.4.0
       - name: 'Cache local Maven repository'
-        uses: actions/cache@v2.1.4
+        uses: actions/cache@v2.1.7
         with:
           path: ~/.m2/repository
           key: maven-${{ hashFiles('**/pom.xml') }}
           restore-keys: |
             maven-
       - name: 'Set up JDK 11'
-        uses: actions/setup-java@v1
+        uses: actions/setup-java@v2
         with:
           java-version: 11
+          distribution: 'zulu'
       - name: 'Generate latest docs'
         env:
           GITHUB_TOKEN: ${{ secrets.GITHUB_TOKEN }}
diff --git a/README-typetools.md b/README-typetools.md
index f552fdfd2b47..686bc55b429b 100644
--- a/README-typetools.md
+++ b/README-typetools.md
@@ -17,6 +17,27 @@ To use a locally-built Checker Framework, add `-P checkerframework-local`,
 or change `guava/pom.xml`.
 
 
+To run the Guava test suite
+---------------------------
+
+This not strictly necessary as the CI process will run them. But if you wish to do so,
+it is a two step process. This can take a long time: 20-30 minutes for the compile step
+and 30-35 minutes for the test step.  In order to shorten it a bit, the command lines
+below only run a single format checker.  First, you must run maven with the install
+target to get a copy of all the generated jar files in your local maven repository:
+
+mvn -V -B -U clean install -Dcheckerframework.checkers=org.checkerframework.checker.formatter.FormatterChecker  \
+    -Dcheck.value.phase=skip -Dmaven.test.skip -Dmaven.javadoc.skip
+
+Then you run the test suite:
+
+MAVEN_OPTS=-Xmx6g mvn -V -B -U verify -Dcheckerframework.checkers=org.checkerframework.checker.formatter.FormatterChecker \
+                      -Dcheck.value.phase=skip -Dmaven.javadoc.skip
+
+Running with the single FormatterChecker gets the total time down to about 20-25 minutes,
+almost all testing. (Over 850,000 tests are run.)
+
+
 Typechecking
 ------------
 
@@ -148,7 +169,7 @@ yet written.
 2. Pull in the latest Guava version (https://github.com/google/guava/releases):
 ```
 git fetch --tags https://github.com/google/guava
-git pull https://github.com/google/guava v30.1.1
+git pull https://github.com/google/guava v31.1
 ```
 
 3. Ensure that the project still builds:
diff --git a/README.md b/README.md
index 67b5a937d05a..8afda8fbb9e0 100644
--- a/README.md
+++ b/README.md
@@ -9,11 +9,11 @@ utilities for concurrency, I/O, hashing, caching, primitives, strings, and more!
 is widely used on most Java projects within Google, and widely used by many
 other companies as well.
 
-Guava comes in two flavors.
+Guava comes in two flavors:
 
 *   The JRE flavor requires JDK 1.8 or higher.
-*   If you need support for JDK 1.7 or Android, use the Android flavor. You can
-    find the Android Guava source in the [`android` directory].
+*   If you need support for Android, use the Android flavor. You can find the
+    Android Guava source in the [`android` directory].
 
 [`android` directory]: https://github.com/google/guava/tree/master/android
 
@@ -21,9 +21,9 @@ Guava comes in two flavors.
 
 Guava's Maven group ID is `com.google.guava`, and its artifact ID is `guava`.
 Guava provides two different "flavors": one for use on a (Java 8+) JRE and one
-for use on Android or Java 7 or by any library that wants to be compatible with
-either of those. These flavors are specified in the Maven version field as
-either `30.1-jre` or `30.1-android`. For more about depending on Guava, see
+for use on Android or by any library that wants to be compatible with Android.
+These flavors are specified in the Maven version field as either `31.1-jre` or
+`31.1-android`. For more about depending on Guava, see
 [using Guava in your build].
 
 To add a dependency on Guava using Maven, use the following:
@@ -32,9 +32,9 @@ To add a dependency on Guava using Maven, use the following:
 <dependency>
   <groupId>com.google.guava</groupId>
   <artifactId>guava</artifactId>
-  <version>30.1-jre</version>
+  <version>31.1-jre</version>
   <!-- or, for Android: -->
-  <version>30.1-android</version>
+  <version>31.1-android</version>
 </dependency>
 ```
 
@@ -45,16 +45,16 @@ dependencies {
   // Pick one:
 
   // 1. Use Guava in your implementation only:
-  implementation("com.google.guava:guava:30.1-jre")
+  implementation("com.google.guava:guava:31.1-jre")
 
   // 2. Use Guava types in your public API:
-  api("com.google.guava:guava:30.1-jre")
+  api("com.google.guava:guava:31.1-jre")
 
   // 3. Android - Use Guava in your implementation only:
-  implementation("com.google.guava:guava:30.1-android")
+  implementation("com.google.guava:guava:31.1-android")
 
   // 4. Android - Use Guava types in your public API:
-  api("com.google.guava:guava:30.1-android")
+  api("com.google.guava:guava:31.1-android")
 }
 ```
 
@@ -101,8 +101,10 @@ flavor.
     plans to start removing things again, but officially, we're leaving our
     options open in case of surprises (like, say, a serious security problem).
 
-3.  Guava has one dependency that is needed at runtime:
-    `com.google.guava:failureaccess:1.0.1`
+3.  Guava has one dependency that is needed for linkage at runtime:
+    `com.google.guava:failureaccess:1.0.1`. It also has
+    [some annotation-only dependencies][guava-deps], which we discuss in more
+    detail at that link.
 
 4.  Serialized forms of ALL objects are subject to change unless noted
     otherwise. Do not persist these and assume they can be read by a future
@@ -111,10 +113,10 @@ flavor.
 5.  Our classes are not designed to protect against a malicious caller. You
     should not use them for communication between trusted and untrusted code.
 
-6.  For the mainline flavor, we unit-test the libraries using only OpenJDK 1.8
-    on Linux. Some features, especially in `com.google.common.io`, may not work
-    correctly in other environments. For the Android flavor, our unit tests run
-    on API level 15 (Ice Cream Sandwich).
+6.  For the mainline flavor, we test the libraries using only OpenJDK 8 and
+    OpenJDK 11 on Linux. Some features, especially in `com.google.common.io`,
+    may not work correctly in other environments. For the Android flavor, our
+    unit tests also run on API level 15 (Ice Cream Sandwich).
 
 [guava-snapshot-api-docs]: https://guava.dev/releases/snapshot-jre/api/docs/
 [guava-snapshot-api-diffs]: https://guava.dev/releases/snapshot-jre/api/diffs/
@@ -125,3 +127,4 @@ flavor.
 
 [using Guava in your build]: https://github.com/google/guava/wiki/UseGuavaInYourBuild
 [repackage]: https://github.com/google/guava/wiki/UseGuavaInYourBuild#what-if-i-want-to-use-beta-apis-from-a-library-that-people-use-as-a-dependency
+[guava-deps]: https://github.com/google/guava/wiki/UseGuavaInYourBuild#what-about-guavas-own-dependencies
diff --git a/android/guava-bom/pom.xml b/android/guava-bom/pom.xml
index 8fde93d1a75a..736c02fd8044 100644
--- a/android/guava-bom/pom.xml
+++ b/android/guava-bom/pom.xml
@@ -8,7 +8,7 @@
 
   <groupId>com.google.guava</groupId>
   <artifactId>guava-bom</artifactId>
-  <version>HEAD-android-SNAPSHOT</version>
+  <version>31.1-android</version>
   <packaging>pom</packaging>
   
   <parent>
diff --git a/android/guava-testlib/pom.xml b/android/guava-testlib/pom.xml
index 79b05190ce85..1fcf058676ee 100644
--- a/android/guava-testlib/pom.xml
+++ b/android/guava-testlib/pom.xml
@@ -5,7 +5,7 @@
   <parent>
     <groupId>com.google.guava</groupId>
     <artifactId>guava-parent</artifactId>
-    <version>HEAD-android-SNAPSHOT</version>
+    <version>31.1-android</version>
   </parent>
   <artifactId>guava-testlib</artifactId>
   <name>Guava Testing Library</name>
@@ -18,10 +18,6 @@
       <groupId>com.google.code.findbugs</groupId>
       <artifactId>jsr305</artifactId>
     </dependency>
-    <dependency>
-      <groupId>org.checkerframework</groupId>
-      <artifactId>checker-compat-qual</artifactId>
-    </dependency>
     <dependency>
       <groupId>com.google.errorprone</groupId>
       <artifactId>error_prone_annotations</artifactId>
diff --git a/android/guava-testlib/src/com/google/common/collect/testing/AbstractContainerTester.java b/android/guava-testlib/src/com/google/common/collect/testing/AbstractContainerTester.java
index a5674d3db4d0..b86ef1750dee 100644
--- a/android/guava-testlib/src/com/google/common/collect/testing/AbstractContainerTester.java
+++ b/android/guava-testlib/src/com/google/common/collect/testing/AbstractContainerTester.java
@@ -188,7 +188,7 @@ protected ArrayWithDuplicate<E> createArrayWithDuplicateElement() {
     E[] elements = createSamplesArray();
     E duplicate = elements[(elements.length / 2) - 1];
     elements[(elements.length / 2) + 1] = duplicate;
-    return new ArrayWithDuplicate<E>(elements, duplicate);
+    return new ArrayWithDuplicate<>(elements, duplicate);
   }
 
   // Helper methods to improve readability of derived classes
@@ -211,7 +211,7 @@ protected Collection<E> getSampleElements() {
    * requirement {@link com.google.common.collect.testing.features.CollectionFeature#KNOWN_ORDER}.
    */
   protected List<E> getOrderedElements() {
-    List<E> list = new ArrayList<E>();
+    List<E> list = new ArrayList<>();
     for (E e : getSubjectGenerator().order(new ArrayList<E>(getSampleElements()))) {
       list.add(e);
     }
diff --git a/android/guava-testlib/src/com/google/common/collect/testing/AbstractMapTester.java b/android/guava-testlib/src/com/google/common/collect/testing/AbstractMapTester.java
index 090442edc4da..5e0de3ccc443 100644
--- a/android/guava-testlib/src/com/google/common/collect/testing/AbstractMapTester.java
+++ b/android/guava-testlib/src/com/google/common/collect/testing/AbstractMapTester.java
@@ -72,8 +72,8 @@ protected void expectMissingValues(V... elements) {
   /** @return an array of the proper size with {@code null} as the key of the middle element. */
   protected Entry<K, V>[] createArrayWithNullKey() {
     Entry<K, V>[] array = createSamplesArray();
-    final int nullKeyLocation = getNullLocation();
-    final Entry<K, V> oldEntry = array[nullKeyLocation];
+    int nullKeyLocation = getNullLocation();
+    Entry<K, V> oldEntry = array[nullKeyLocation];
     array[nullKeyLocation] = entry(null, oldEntry.getValue());
     return array;
   }
@@ -97,8 +97,8 @@ private Entry<K, V> getEntryNullReplaces() {
   /** @return an array of the proper size with {@code null} as the value of the middle element. */
   protected Entry<K, V>[] createArrayWithNullValue() {
     Entry<K, V>[] array = createSamplesArray();
-    final int nullValueLocation = getNullLocation();
-    final Entry<K, V> oldEntry = array[nullValueLocation];
+    int nullValueLocation = getNullLocation();
+    Entry<K, V> oldEntry = array[nullValueLocation];
     array[nullValueLocation] = entry(oldEntry.getKey(), null);
     return array;
   }
diff --git a/android/guava-testlib/src/com/google/common/collect/testing/CollectionTestSuiteBuilder.java b/android/guava-testlib/src/com/google/common/collect/testing/CollectionTestSuiteBuilder.java
index cf1ed23aa41e..5f9aff4f1c5f 100644
--- a/android/guava-testlib/src/com/google/common/collect/testing/CollectionTestSuiteBuilder.java
+++ b/android/guava-testlib/src/com/google/common/collect/testing/CollectionTestSuiteBuilder.java
@@ -57,6 +57,8 @@ protected List<TestSuite> createDerivedSuites(
               .named(getName() + " reserialized")
               .withFeatures(computeReserializedCollectionFeatures(parentBuilder.getFeatures()))
               .suppressing(parentBuilder.getSuppressedTests())
+              .withSetUp(parentBuilder.getSetUp())
+              .withTearDown(parentBuilder.getTearDown())
               .createTestSuite());
     }
     return derivedSuites;
diff --git a/android/guava-testlib/src/com/google/common/collect/testing/DerivedCollectionGenerators.java b/android/guava-testlib/src/com/google/common/collect/testing/DerivedCollectionGenerators.java
index 3588e856fa23..a04d3ffe300a 100644
--- a/android/guava-testlib/src/com/google/common/collect/testing/DerivedCollectionGenerators.java
+++ b/android/guava-testlib/src/com/google/common/collect/testing/DerivedCollectionGenerators.java
@@ -96,9 +96,9 @@ public static class MapKeySetGenerator<K, V> implements TestSetGenerator<K>, Der
 
     public MapKeySetGenerator(OneSizeTestContainerGenerator<Map<K, V>, Entry<K, V>> mapGenerator) {
       this.mapGenerator = mapGenerator;
-      final SampleElements<Entry<K, V>> mapSamples = this.mapGenerator.samples();
+      SampleElements<Entry<K, V>> mapSamples = this.mapGenerator.samples();
       this.samples =
-          new SampleElements<K>(
+          new SampleElements<>(
               mapSamples.e0().getKey(),
               mapSamples.e1().getKey(),
               mapSamples.e2().getKey(),
@@ -203,9 +203,9 @@ public static class MapValueCollectionGenerator<K, V>
     public MapValueCollectionGenerator(
         OneSizeTestContainerGenerator<Map<K, V>, Entry<K, V>> mapGenerator) {
       this.mapGenerator = mapGenerator;
-      final SampleElements<Entry<K, V>> mapSamples = this.mapGenerator.samples();
+      SampleElements<Entry<K, V>> mapSamples = this.mapGenerator.samples();
       this.samples =
-          new SampleElements<V>(
+          new SampleElements<>(
               mapSamples.e0().getValue(),
               mapSamples.e1().getValue(),
               mapSamples.e2().getValue(),
@@ -239,14 +239,13 @@ public Collection<V> create(Object... elements) {
     @Override
     public V[] createArray(int length) {
       // noinspection UnnecessaryLocalVariable
-      final V[] vs =
-          ((TestMapGenerator<K, V>) mapGenerator.getInnerGenerator()).createValueArray(length);
+      V[] vs = ((TestMapGenerator<K, V>) mapGenerator.getInnerGenerator()).createValueArray(length);
       return vs;
     }
 
     @Override
     public Iterable<V> order(List<V> insertionOrder) {
-      final List<Entry<K, V>> orderedEntries =
+      List<Entry<K, V>> orderedEntries =
           castOrCopyToList(mapGenerator.order(castOrCopyToList(mapGenerator.getSampleElements(5))));
       sort(
           insertionOrder,
diff --git a/android/guava-testlib/src/com/google/common/collect/testing/FeatureSpecificTestSuiteBuilder.java b/android/guava-testlib/src/com/google/common/collect/testing/FeatureSpecificTestSuiteBuilder.java
index 0d921a580896..db086aa3075e 100644
--- a/android/guava-testlib/src/com/google/common/collect/testing/FeatureSpecificTestSuiteBuilder.java
+++ b/android/guava-testlib/src/com/google/common/collect/testing/FeatureSpecificTestSuiteBuilder.java
@@ -81,7 +81,7 @@ public B withSetUp(Runnable setUp) {
     return self();
   }
 
-  protected Runnable getSetUp() {
+  public Runnable getSetUp() {
     return setUp;
   }
 
@@ -90,13 +90,13 @@ public B withTearDown(Runnable tearDown) {
     return self();
   }
 
-  protected Runnable getTearDown() {
+  public Runnable getTearDown() {
     return tearDown;
   }
 
   // Features
 
-  private Set<Feature<?>> features = new LinkedHashSet<>();
+  private final Set<Feature<?>> features = new LinkedHashSet<>();
 
   /**
    * Configures this builder to produce tests appropriate for the given features. This method may be
@@ -138,7 +138,7 @@ public String getName() {
 
   // Test suppression
 
-  private Set<Method> suppressedTests = new HashSet<>();
+  private final Set<Method> suppressedTests = new HashSet<>();
 
   /**
    * Prevents the given methods from being run as part of the test suite.
@@ -185,7 +185,7 @@ public TestSuite createTestSuite() {
 
     TestSuite suite = new TestSuite(name);
     for (Class<? extends AbstractTester> testerClass : testers) {
-      final TestSuite testerSuite =
+      TestSuite testerSuite =
           makeSuiteForTesterClass((Class<? extends AbstractTester<?>>) testerClass);
       if (testerSuite.countTestCases() > 0) {
         suite.addTest(testerSuite);
@@ -211,7 +211,7 @@ protected void checkCanCreate() {
   protected abstract List<Class<? extends AbstractTester>> getTesters();
 
   private boolean matches(Test test) {
-    final Method method;
+    Method method;
     try {
       method = extractMethod(test);
     } catch (IllegalArgumentException e) {
@@ -222,7 +222,7 @@ private boolean matches(Test test) {
       logger.finer(Platform.format("%s: excluding because it was explicitly suppressed.", test));
       return false;
     }
-    final TesterRequirements requirements;
+    TesterRequirements requirements;
     try {
       requirements = FeatureUtil.getTesterRequirements(method);
     } catch (ConflictingRequirementsException e) {
@@ -268,8 +268,8 @@ private static Method extractMethod(Test test) {
   }
 
   protected TestSuite makeSuiteForTesterClass(Class<? extends AbstractTester<?>> testerClass) {
-    final TestSuite candidateTests = new TestSuite(testerClass);
-    final TestSuite suite = filterSuite(candidateTests);
+    TestSuite candidateTests = new TestSuite(testerClass);
+    TestSuite suite = filterSuite(candidateTests);
 
     Enumeration<?> allTests = suite.tests();
     while (allTests.hasMoreElements()) {
@@ -286,7 +286,7 @@ protected TestSuite makeSuiteForTesterClass(Class<? extends AbstractTester<?>> t
 
   private TestSuite filterSuite(TestSuite suite) {
     TestSuite filtered = new TestSuite(suite.getName());
-    final Enumeration<?> tests = suite.tests();
+    Enumeration<?> tests = suite.tests();
     while (tests.hasMoreElements()) {
       Test test = (Test) tests.nextElement();
       if (matches(test)) {
diff --git a/android/guava-testlib/src/com/google/common/collect/testing/Helpers.java b/android/guava-testlib/src/com/google/common/collect/testing/Helpers.java
index 8efafc373525..aac71cc4efe3 100644
--- a/android/guava-testlib/src/com/google/common/collect/testing/Helpers.java
+++ b/android/guava-testlib/src/com/google/common/collect/testing/Helpers.java
@@ -49,7 +49,7 @@ static boolean equal(Object a, Object b) {
 
   // Clone of Lists.newArrayList
   public static <E> List<E> copyToList(Iterable<? extends E> elements) {
-    List<E> list = new ArrayList<E>();
+    List<E> list = new ArrayList<>();
     addAll(list, elements);
     return list;
   }
@@ -60,7 +60,7 @@ public static <E> List<E> copyToList(E[] elements) {
 
   // Clone of Sets.newLinkedHashSet
   public static <E> Set<E> copyToSet(Iterable<? extends E> elements) {
-    Set<E> set = new LinkedHashSet<E>();
+    Set<E> set = new LinkedHashSet<>();
     addAll(set, elements);
     return set;
   }
@@ -188,11 +188,11 @@ public static <E> boolean addAll(Collection<E> addTo, Iterable<? extends E> elem
     return modified;
   }
 
-  static <T> Iterable<T> reverse(final List<T> list) {
+  static <T> Iterable<T> reverse(List<T> list) {
     return new Iterable<T>() {
       @Override
       public Iterator<T> iterator() {
-        final ListIterator<T> listIter = list.listIterator(list.size());
+        ListIterator<T> listIter = list.listIterator(list.size());
         return new Iterator<T>() {
           @Override
           public boolean hasNext() {
@@ -213,7 +213,7 @@ public void remove() {
     };
   }
 
-  static <T> Iterator<T> cycle(final Iterable<T> iterable) {
+  static <T> Iterator<T> cycle(Iterable<T> iterable) {
     return new Iterator<T>() {
       Iterator<T> iterator = Collections.<T>emptySet().iterator();
 
@@ -251,7 +251,7 @@ static void fail(Throwable cause, Object message) {
   }
 
   public static <K, V> Comparator<Entry<K, V>> entryComparator(
-      final Comparator<? super K> keyComparator) {
+      Comparator<? super K> keyComparator) {
     return new Comparator<Entry<K, V>>() {
       @Override
       @SuppressWarnings("unchecked") // no less safe than putting it in the map!
@@ -345,7 +345,7 @@ public static <T extends Comparable<? super T>> void testCompareToAndEquals(
    * @param delta the difference between the true size of the collection and the values returned by
    *     the size method
    */
-  public static <T> Collection<T> misleadingSizeCollection(final int delta) {
+  public static <T> Collection<T> misleadingSizeCollection(int delta) {
     // It would be nice to be able to return a real concurrent
     // collection like ConcurrentLinkedQueue, so that e.g. concurrent
     // iteration would work, but that would not be GWT-compatible.
@@ -363,7 +363,7 @@ public int size() {
    * equals. This is used for testing unmodifiable collections of map entries; for example, it
    * should not be possible to access the raw (modifiable) map entry via a nefarious equals method.
    */
-  public static <K, V> Entry<K, V> nefariousMapEntry(final K key, final V value) {
+  public static <K, V> Entry<K, V> nefariousMapEntry(K key, V value) {
     return new Entry<K, V>() {
       @Override
       public K getKey() {
@@ -410,7 +410,7 @@ static <E> List<E> castOrCopyToList(Iterable<E> iterable) {
     if (iterable instanceof List) {
       return (List<E>) iterable;
     }
-    List<E> list = new ArrayList<E>();
+    List<E> list = new ArrayList<>();
     for (E e : iterable) {
       list.add(e);
     }
diff --git a/android/guava-testlib/src/com/google/common/collect/testing/ListTestSuiteBuilder.java b/android/guava-testlib/src/com/google/common/collect/testing/ListTestSuiteBuilder.java
index e01056459338..061e31038bda 100644
--- a/android/guava-testlib/src/com/google/common/collect/testing/ListTestSuiteBuilder.java
+++ b/android/guava-testlib/src/com/google/common/collect/testing/ListTestSuiteBuilder.java
@@ -112,6 +112,8 @@ protected List<TestSuite> createDerivedSuites(
               .named(getName() + " reserialized")
               .withFeatures(computeReserializedCollectionFeatures(parentBuilder.getFeatures()))
               .suppressing(parentBuilder.getSuppressedTests())
+              .withSetUp(parentBuilder.getSetUp())
+              .withTearDown(parentBuilder.getTearDown())
               .createTestSuite());
     }
     return derivedSuites;
diff --git a/android/guava-testlib/src/com/google/common/collect/testing/MapInterfaceTest.java b/android/guava-testlib/src/com/google/common/collect/testing/MapInterfaceTest.java
index b8b5c28fb936..48491387851f 100644
--- a/android/guava-testlib/src/com/google/common/collect/testing/MapInterfaceTest.java
+++ b/android/guava-testlib/src/com/google/common/collect/testing/MapInterfaceTest.java
@@ -149,7 +149,7 @@ protected final boolean supportsValuesHashCode(Map<K, V> map) {
     for (V value : values) {
       if (value != null) {
         try {
-          value.hashCode();
+          int unused = value.hashCode();
         } catch (Exception e) {
           return false;
         }
@@ -265,7 +265,7 @@ private void assertEntrySetNotContainsString(Set<Entry<K, V>> entrySet) {
   protected void assertMoreInvariants(Map<K, V> map) {}
 
   public void testClear() {
-    final Map<K, V> map;
+    Map<K, V> map;
     try {
       map = makePopulatedMap();
     } catch (UnsupportedOperationException e) {
@@ -286,8 +286,8 @@ public void testClear() {
   }
 
   public void testContainsKey() {
-    final Map<K, V> map;
-    final K unmappedKey;
+    Map<K, V> map;
+    K unmappedKey;
     try {
       map = makePopulatedMap();
       unmappedKey = getKeyNotInPopulatedMap();
@@ -312,8 +312,8 @@ public void testContainsKey() {
   }
 
   public void testContainsValue() {
-    final Map<K, V> map;
-    final V unmappedValue;
+    Map<K, V> map;
+    V unmappedValue;
     try {
       map = makePopulatedMap();
       unmappedValue = getValueNotInPopulatedMap();
@@ -334,8 +334,8 @@ public void testContainsValue() {
   }
 
   public void testEntrySet() {
-    final Map<K, V> map;
-    final Set<Entry<K, V>> entrySet;
+    Map<K, V> map;
+    Set<Entry<K, V>> entrySet;
     try {
       map = makePopulatedMap();
     } catch (UnsupportedOperationException e) {
@@ -344,8 +344,8 @@ public void testEntrySet() {
     assertInvariants(map);
 
     entrySet = map.entrySet();
-    final K unmappedKey;
-    final V unmappedValue;
+    K unmappedKey;
+    V unmappedValue;
     try {
       unmappedKey = getKeyNotInPopulatedMap();
       unmappedValue = getValueNotInPopulatedMap();
@@ -359,7 +359,7 @@ public void testEntrySet() {
   }
 
   public void testEntrySetForEmptyMap() {
-    final Map<K, V> map;
+    Map<K, V> map;
     try {
       map = makeEmptyMap();
     } catch (UnsupportedOperationException e) {
@@ -369,8 +369,8 @@ public void testEntrySetForEmptyMap() {
   }
 
   public void testEntrySetContainsEntryIncompatibleKey() {
-    final Map<K, V> map;
-    final Set<Entry<K, V>> entrySet;
+    Map<K, V> map;
+    Set<Entry<K, V>> entrySet;
     try {
       map = makeEitherMap();
     } catch (UnsupportedOperationException e) {
@@ -379,7 +379,7 @@ public void testEntrySetContainsEntryIncompatibleKey() {
     assertInvariants(map);
 
     entrySet = map.entrySet();
-    final V unmappedValue;
+    V unmappedValue;
     try {
       unmappedValue = getValueNotInPopulatedMap();
     } catch (UnsupportedOperationException e) {
@@ -396,8 +396,8 @@ public void testEntrySetContainsEntryNullKeyPresent() {
     if (!allowsNullKeys || !supportsPut) {
       return;
     }
-    final Map<K, V> map;
-    final Set<Entry<K, V>> entrySet;
+    Map<K, V> map;
+    Set<Entry<K, V>> entrySet;
     try {
       map = makeEitherMap();
     } catch (UnsupportedOperationException e) {
@@ -406,7 +406,7 @@ public void testEntrySetContainsEntryNullKeyPresent() {
     assertInvariants(map);
 
     entrySet = map.entrySet();
-    final V unmappedValue;
+    V unmappedValue;
     try {
       unmappedValue = getValueNotInPopulatedMap();
     } catch (UnsupportedOperationException e) {
@@ -420,8 +420,8 @@ public void testEntrySetContainsEntryNullKeyPresent() {
   }
 
   public void testEntrySetContainsEntryNullKeyMissing() {
-    final Map<K, V> map;
-    final Set<Entry<K, V>> entrySet;
+    Map<K, V> map;
+    Set<Entry<K, V>> entrySet;
     try {
       map = makeEitherMap();
     } catch (UnsupportedOperationException e) {
@@ -430,7 +430,7 @@ public void testEntrySetContainsEntryNullKeyMissing() {
     assertInvariants(map);
 
     entrySet = map.entrySet();
-    final V unmappedValue;
+    V unmappedValue;
     try {
       unmappedValue = getValueNotInPopulatedMap();
     } catch (UnsupportedOperationException e) {
@@ -450,7 +450,7 @@ public void testEntrySetContainsEntryNullKeyMissing() {
   }
 
   public void testEntrySetIteratorRemove() {
-    final Map<K, V> map;
+    Map<K, V> map;
     try {
       map = makePopulatedMap();
     } catch (UnsupportedOperationException e) {
@@ -488,7 +488,7 @@ public void testEntrySetIteratorRemove() {
   }
 
   public void testEntrySetRemove() {
-    final Map<K, V> map;
+    Map<K, V> map;
     try {
       map = makePopulatedMap();
     } catch (UnsupportedOperationException e) {
@@ -512,8 +512,8 @@ public void testEntrySetRemove() {
   }
 
   public void testEntrySetRemoveMissingKey() {
-    final Map<K, V> map;
-    final K key;
+    Map<K, V> map;
+    K key;
     try {
       map = makeEitherMap();
       key = getKeyNotInPopulatedMap();
@@ -540,7 +540,7 @@ public void testEntrySetRemoveMissingKey() {
   }
 
   public void testEntrySetRemoveDifferentValue() {
-    final Map<K, V> map;
+    Map<K, V> map;
     try {
       map = makePopulatedMap();
     } catch (UnsupportedOperationException e) {
@@ -570,8 +570,8 @@ public void testEntrySetRemoveNullKeyPresent() {
     if (!allowsNullKeys || !supportsPut || !supportsRemove) {
       return;
     }
-    final Map<K, V> map;
-    final Set<Entry<K, V>> entrySet;
+    Map<K, V> map;
+    Set<Entry<K, V>> entrySet;
     try {
       map = makeEitherMap();
     } catch (UnsupportedOperationException e) {
@@ -580,7 +580,7 @@ public void testEntrySetRemoveNullKeyPresent() {
     assertInvariants(map);
 
     entrySet = map.entrySet();
-    final V unmappedValue;
+    V unmappedValue;
     try {
       unmappedValue = getValueNotInPopulatedMap();
     } catch (UnsupportedOperationException e) {
@@ -597,7 +597,7 @@ public void testEntrySetRemoveNullKeyPresent() {
   }
 
   public void testEntrySetRemoveNullKeyMissing() {
-    final Map<K, V> map;
+    Map<K, V> map;
     try {
       map = makeEitherMap();
     } catch (UnsupportedOperationException e) {
@@ -626,7 +626,7 @@ public void testEntrySetRemoveNullKeyMissing() {
   }
 
   public void testEntrySetRemoveAll() {
-    final Map<K, V> map;
+    Map<K, V> map;
     try {
       map = makePopulatedMap();
     } catch (UnsupportedOperationException e) {
@@ -663,7 +663,7 @@ public void testEntrySetRemoveAll() {
   }
 
   public void testEntrySetRemoveAllNullFromEmpty() {
-    final Map<K, V> map;
+    Map<K, V> map;
     try {
       map = makeEmptyMap();
     } catch (UnsupportedOperationException e) {
@@ -689,7 +689,7 @@ public void testEntrySetRemoveAllNullFromEmpty() {
   }
 
   public void testEntrySetRetainAll() {
-    final Map<K, V> map;
+    Map<K, V> map;
     try {
       map = makePopulatedMap();
     } catch (UnsupportedOperationException e) {
@@ -717,7 +717,7 @@ public void testEntrySetRetainAll() {
   }
 
   public void testEntrySetRetainAllNullFromEmpty() {
-    final Map<K, V> map;
+    Map<K, V> map;
     try {
       map = makeEmptyMap();
     } catch (UnsupportedOperationException e) {
@@ -743,7 +743,7 @@ public void testEntrySetRetainAllNullFromEmpty() {
   }
 
   public void testEntrySetClear() {
-    final Map<K, V> map;
+    Map<K, V> map;
     try {
       map = makePopulatedMap();
     } catch (UnsupportedOperationException e) {
@@ -765,10 +765,10 @@ public void testEntrySetClear() {
   }
 
   public void testEntrySetAddAndAddAll() {
-    final Map<K, V> map = makeEitherMap();
+    Map<K, V> map = makeEitherMap();
 
     Set<Entry<K, V>> entrySet = map.entrySet();
-    final Entry<K, V> entryToAdd = mapEntry(null, null);
+    Entry<K, V> entryToAdd = mapEntry(null, null);
     try {
       entrySet.add(entryToAdd);
       fail("Expected UnsupportedOperationException or NullPointerException.");
@@ -793,8 +793,8 @@ public void testEntrySetSetValue() {
       return;
     }
 
-    final Map<K, V> map;
-    final V valueToSet;
+    Map<K, V> map;
+    V valueToSet;
     try {
       map = makePopulatedMap();
       valueToSet = getValueNotInPopulatedMap();
@@ -804,8 +804,8 @@ public void testEntrySetSetValue() {
 
     Set<Entry<K, V>> entrySet = map.entrySet();
     Entry<K, V> entry = entrySet.iterator().next();
-    final V oldValue = entry.getValue();
-    final V returnedValue = entry.setValue(valueToSet);
+    V oldValue = entry.getValue();
+    V returnedValue = entry.setValue(valueToSet);
     assertEquals(oldValue, returnedValue);
     assertTrue(entrySet.contains(mapEntry(entry.getKey(), valueToSet)));
     assertEquals(valueToSet, map.get(entry.getKey()));
@@ -819,7 +819,7 @@ public void testEntrySetSetValueSameValue() {
       return;
     }
 
-    final Map<K, V> map;
+    Map<K, V> map;
     try {
       map = makePopulatedMap();
     } catch (UnsupportedOperationException e) {
@@ -828,8 +828,8 @@ public void testEntrySetSetValueSameValue() {
 
     Set<Entry<K, V>> entrySet = map.entrySet();
     Entry<K, V> entry = entrySet.iterator().next();
-    final V oldValue = entry.getValue();
-    final V returnedValue = entry.setValue(oldValue);
+    V oldValue = entry.getValue();
+    V returnedValue = entry.setValue(oldValue);
     assertEquals(oldValue, returnedValue);
     assertTrue(entrySet.contains(mapEntry(entry.getKey(), oldValue)));
     assertEquals(oldValue, map.get(entry.getKey()));
@@ -837,15 +837,16 @@ public void testEntrySetSetValueSameValue() {
   }
 
   public void testEqualsForEqualMap() {
-    final Map<K, V> map;
+    Map<K, V> map;
     try {
       map = makePopulatedMap();
     } catch (UnsupportedOperationException e) {
       return;
     }
 
-    assertEquals(map, map);
-    assertEquals(makePopulatedMap(), map);
+    // Explicitly call `equals`; `assertEquals` might return fast
+    assertTrue(map.equals(map));
+    assertTrue(makePopulatedMap().equals(map));
     assertFalse(map.equals(Collections.emptyMap()));
     // no-inspection ObjectEqualsNull
     assertFalse(map.equals(null));
@@ -856,8 +857,8 @@ public void testEqualsForLargerMap() {
       return;
     }
 
-    final Map<K, V> map;
-    final Map<K, V> largerMap;
+    Map<K, V> map;
+    Map<K, V> largerMap;
     try {
       map = makePopulatedMap();
       largerMap = makePopulatedMap();
@@ -874,8 +875,8 @@ public void testEqualsForSmallerMap() {
       return;
     }
 
-    final Map<K, V> map;
-    final Map<K, V> smallerMap;
+    Map<K, V> map;
+    Map<K, V> smallerMap;
     try {
       map = makePopulatedMap();
       smallerMap = makePopulatedMap();
@@ -888,15 +889,16 @@ public void testEqualsForSmallerMap() {
   }
 
   public void testEqualsForEmptyMap() {
-    final Map<K, V> map;
+    Map<K, V> map;
     try {
       map = makeEmptyMap();
     } catch (UnsupportedOperationException e) {
       return;
     }
 
-    assertEquals(map, map);
-    assertEquals(makeEmptyMap(), map);
+    // Explicitly call `equals`; `assertEquals` might return fast
+    assertTrue(map.equals(map));
+    assertTrue(makeEmptyMap().equals(map));
     assertEquals(Collections.emptyMap(), map);
     assertFalse(map.equals(Collections.emptySet()));
     // noinspection ObjectEqualsNull
@@ -904,7 +906,7 @@ public void testEqualsForEmptyMap() {
   }
 
   public void testGet() {
-    final Map<K, V> map;
+    Map<K, V> map;
     try {
       map = makePopulatedMap();
     } catch (UnsupportedOperationException e) {
@@ -925,7 +927,7 @@ public void testGet() {
   }
 
   public void testGetForEmptyMap() {
-    final Map<K, V> map;
+    Map<K, V> map;
     K unmappedKey = null;
     try {
       map = makeEmptyMap();
@@ -954,7 +956,7 @@ public void testGetNull() {
   }
 
   public void testHashCode() {
-    final Map<K, V> map;
+    Map<K, V> map;
     try {
       map = makePopulatedMap();
     } catch (UnsupportedOperationException e) {
@@ -964,7 +966,7 @@ public void testHashCode() {
   }
 
   public void testHashCodeForEmptyMap() {
-    final Map<K, V> map;
+    Map<K, V> map;
     try {
       map = makeEmptyMap();
     } catch (UnsupportedOperationException e) {
@@ -974,9 +976,9 @@ public void testHashCodeForEmptyMap() {
   }
 
   public void testPutNewKey() {
-    final Map<K, V> map = makeEitherMap();
-    final K keyToPut;
-    final V valueToPut;
+    Map<K, V> map = makeEitherMap();
+    K keyToPut;
+    V valueToPut;
     try {
       keyToPut = getKeyNotInPopulatedMap();
       valueToPut = getValueNotInPopulatedMap();
@@ -1002,9 +1004,9 @@ public void testPutNewKey() {
   }
 
   public void testPutExistingKey() {
-    final Map<K, V> map;
-    final K keyToPut;
-    final V valueToPut;
+    Map<K, V> map;
+    K keyToPut;
+    V valueToPut;
     try {
       map = makePopulatedMap();
       valueToPut = getValueNotInPopulatedMap();
@@ -1033,16 +1035,16 @@ public void testPutNullKey() {
     if (!supportsPut) {
       return;
     }
-    final Map<K, V> map = makeEitherMap();
-    final V valueToPut;
+    Map<K, V> map = makeEitherMap();
+    V valueToPut;
     try {
       valueToPut = getValueNotInPopulatedMap();
     } catch (UnsupportedOperationException e) {
       return;
     }
     if (allowsNullKeys) {
-      final V oldValue = map.get(null);
-      final V returnedValue = map.put(null, valueToPut);
+      V oldValue = map.get(null);
+      V returnedValue = map.put(null, valueToPut);
       assertEquals(oldValue, returnedValue);
       assertEquals(valueToPut, map.get(null));
       assertTrue(map.containsKey(null));
@@ -1061,8 +1063,8 @@ public void testPutNullValue() {
     if (!supportsPut) {
       return;
     }
-    final Map<K, V> map = makeEitherMap();
-    final K keyToPut;
+    Map<K, V> map = makeEitherMap();
+    K keyToPut;
     try {
       keyToPut = getKeyNotInPopulatedMap();
     } catch (UnsupportedOperationException e) {
@@ -1070,8 +1072,8 @@ public void testPutNullValue() {
     }
     if (allowsNullValues) {
       int initialSize = map.size();
-      final V oldValue = map.get(keyToPut);
-      final V returnedValue = map.put(keyToPut, null);
+      V oldValue = map.get(keyToPut);
+      V returnedValue = map.put(keyToPut, null);
       assertEquals(oldValue, returnedValue);
       assertNull(map.get(keyToPut));
       assertTrue(map.containsKey(keyToPut));
@@ -1091,8 +1093,8 @@ public void testPutNullValueForExistingKey() {
     if (!supportsPut) {
       return;
     }
-    final Map<K, V> map;
-    final K keyToPut;
+    Map<K, V> map;
+    K keyToPut;
     try {
       map = makePopulatedMap();
       keyToPut = map.keySet().iterator().next();
@@ -1101,8 +1103,8 @@ public void testPutNullValueForExistingKey() {
     }
     if (allowsNullValues) {
       int initialSize = map.size();
-      final V oldValue = map.get(keyToPut);
-      final V returnedValue = map.put(keyToPut, null);
+      V oldValue = map.get(keyToPut);
+      V returnedValue = map.put(keyToPut, null);
       assertEquals(oldValue, returnedValue);
       assertNull(map.get(keyToPut));
       assertTrue(map.containsKey(keyToPut));
@@ -1119,16 +1121,16 @@ public void testPutNullValueForExistingKey() {
   }
 
   public void testPutAllNewKey() {
-    final Map<K, V> map = makeEitherMap();
-    final K keyToPut;
-    final V valueToPut;
+    Map<K, V> map = makeEitherMap();
+    K keyToPut;
+    V valueToPut;
     try {
       keyToPut = getKeyNotInPopulatedMap();
       valueToPut = getValueNotInPopulatedMap();
     } catch (UnsupportedOperationException e) {
       return;
     }
-    final Map<K, V> mapToPut = Collections.singletonMap(keyToPut, valueToPut);
+    Map<K, V> mapToPut = Collections.singletonMap(keyToPut, valueToPut);
     if (supportsPut) {
       int initialSize = map.size();
       map.putAll(mapToPut);
@@ -1147,9 +1149,9 @@ public void testPutAllNewKey() {
   }
 
   public void testPutAllExistingKey() {
-    final Map<K, V> map;
-    final K keyToPut;
-    final V valueToPut;
+    Map<K, V> map;
+    K keyToPut;
+    V valueToPut;
     try {
       map = makePopulatedMap();
       valueToPut = getValueNotInPopulatedMap();
@@ -1157,7 +1159,7 @@ public void testPutAllExistingKey() {
       return;
     }
     keyToPut = map.keySet().iterator().next();
-    final Map<K, V> mapToPut = Collections.singletonMap(keyToPut, valueToPut);
+    Map<K, V> mapToPut = Collections.singletonMap(keyToPut, valueToPut);
     int initialSize = map.size();
     if (supportsPut) {
       map.putAll(mapToPut);
@@ -1176,8 +1178,8 @@ public void testPutAllExistingKey() {
   }
 
   public void testRemove() {
-    final Map<K, V> map;
-    final K keyToRemove;
+    Map<K, V> map;
+    K keyToRemove;
     try {
       map = makePopulatedMap();
     } catch (UnsupportedOperationException e) {
@@ -1202,8 +1204,8 @@ public void testRemove() {
   }
 
   public void testRemoveMissingKey() {
-    final Map<K, V> map;
-    final K keyToRemove;
+    Map<K, V> map;
+    K keyToRemove;
     try {
       map = makePopulatedMap();
       keyToRemove = getKeyNotInPopulatedMap();
@@ -1229,7 +1231,7 @@ public void testSize() {
   }
 
   public void testKeySetRemove() {
-    final Map<K, V> map;
+    Map<K, V> map;
     try {
       map = makePopulatedMap();
     } catch (UnsupportedOperationException e) {
@@ -1254,7 +1256,7 @@ public void testKeySetRemove() {
   }
 
   public void testKeySetRemoveAll() {
-    final Map<K, V> map;
+    Map<K, V> map;
     try {
       map = makePopulatedMap();
     } catch (UnsupportedOperationException e) {
@@ -1279,7 +1281,7 @@ public void testKeySetRemoveAll() {
   }
 
   public void testKeySetRetainAll() {
-    final Map<K, V> map;
+    Map<K, V> map;
     try {
       map = makePopulatedMap();
     } catch (UnsupportedOperationException e) {
@@ -1303,7 +1305,7 @@ public void testKeySetRetainAll() {
   }
 
   public void testKeySetClear() {
-    final Map<K, V> map;
+    Map<K, V> map;
     try {
       map = makeEitherMap();
     } catch (UnsupportedOperationException e) {
@@ -1325,7 +1327,7 @@ public void testKeySetClear() {
   }
 
   public void testKeySetRemoveAllNullFromEmpty() {
-    final Map<K, V> map;
+    Map<K, V> map;
     try {
       map = makeEmptyMap();
     } catch (UnsupportedOperationException e) {
@@ -1351,7 +1353,7 @@ public void testKeySetRemoveAllNullFromEmpty() {
   }
 
   public void testKeySetRetainAllNullFromEmpty() {
-    final Map<K, V> map;
+    Map<K, V> map;
     try {
       map = makeEmptyMap();
     } catch (UnsupportedOperationException e) {
@@ -1377,8 +1379,8 @@ public void testKeySetRetainAllNullFromEmpty() {
   }
 
   public void testValues() {
-    final Map<K, V> map;
-    final Collection<V> valueCollection;
+    Map<K, V> map;
+    Collection<V> valueCollection;
     try {
       map = makePopulatedMap();
     } catch (UnsupportedOperationException e) {
@@ -1387,7 +1389,7 @@ public void testValues() {
     assertInvariants(map);
 
     valueCollection = map.values();
-    final V unmappedValue;
+    V unmappedValue;
     try {
       unmappedValue = getValueNotInPopulatedMap();
     } catch (UnsupportedOperationException e) {
@@ -1399,7 +1401,7 @@ public void testValues() {
   }
 
   public void testValuesIteratorRemove() {
-    final Map<K, V> map;
+    Map<K, V> map;
     try {
       map = makePopulatedMap();
     } catch (UnsupportedOperationException e) {
@@ -1434,7 +1436,7 @@ public void testValuesIteratorRemove() {
   }
 
   public void testValuesRemove() {
-    final Map<K, V> map;
+    Map<K, V> map;
     try {
       map = makePopulatedMap();
     } catch (UnsupportedOperationException e) {
@@ -1460,8 +1462,8 @@ public void testValuesRemove() {
   }
 
   public void testValuesRemoveMissing() {
-    final Map<K, V> map;
-    final V valueToRemove;
+    Map<K, V> map;
+    V valueToRemove;
     try {
       map = makeEitherMap();
       valueToRemove = getValueNotInPopulatedMap();
@@ -1485,7 +1487,7 @@ public void testValuesRemoveMissing() {
   }
 
   public void testValuesRemoveAll() {
-    final Map<K, V> map;
+    Map<K, V> map;
     try {
       map = makePopulatedMap();
     } catch (UnsupportedOperationException e) {
@@ -1513,7 +1515,7 @@ public void testValuesRemoveAll() {
   }
 
   public void testValuesRemoveAllNullFromEmpty() {
-    final Map<K, V> map;
+    Map<K, V> map;
     try {
       map = makeEmptyMap();
     } catch (UnsupportedOperationException e) {
@@ -1539,7 +1541,7 @@ public void testValuesRemoveAllNullFromEmpty() {
   }
 
   public void testValuesRetainAll() {
-    final Map<K, V> map;
+    Map<K, V> map;
     try {
       map = makePopulatedMap();
     } catch (UnsupportedOperationException e) {
@@ -1567,7 +1569,7 @@ public void testValuesRetainAll() {
   }
 
   public void testValuesRetainAllNullFromEmpty() {
-    final Map<K, V> map;
+    Map<K, V> map;
     try {
       map = makeEmptyMap();
     } catch (UnsupportedOperationException e) {
@@ -1593,7 +1595,7 @@ public void testValuesRetainAllNullFromEmpty() {
   }
 
   public void testValuesClear() {
-    final Map<K, V> map;
+    Map<K, V> map;
     try {
       map = makePopulatedMap();
     } catch (UnsupportedOperationException e) {
diff --git a/android/guava-testlib/src/com/google/common/collect/testing/MapTestSuiteBuilder.java b/android/guava-testlib/src/com/google/common/collect/testing/MapTestSuiteBuilder.java
index 7bb418f5a97b..7b8e40a2b1aa 100644
--- a/android/guava-testlib/src/com/google/common/collect/testing/MapTestSuiteBuilder.java
+++ b/android/guava-testlib/src/com/google/common/collect/testing/MapTestSuiteBuilder.java
@@ -101,6 +101,8 @@ protected List<TestSuite> createDerivedSuites(
               .withFeatures(computeReserializedMapFeatures(parentBuilder.getFeatures()))
               .named(parentBuilder.getName() + " reserialized")
               .suppressing(parentBuilder.getSuppressedTests())
+              .withSetUp(parentBuilder.getSetUp())
+              .withTearDown(parentBuilder.getTearDown())
               .createTestSuite());
     }
 
@@ -110,6 +112,8 @@ protected List<TestSuite> createDerivedSuites(
             .withFeatures(computeEntrySetFeatures(parentBuilder.getFeatures()))
             .named(parentBuilder.getName() + " entrySet")
             .suppressing(parentBuilder.getSuppressedTests())
+            .withSetUp(parentBuilder.getSetUp())
+            .withTearDown(parentBuilder.getTearDown())
             .createTestSuite());
 
     derivedSuites.add(
@@ -117,6 +121,8 @@ protected List<TestSuite> createDerivedSuites(
             .withFeatures(computeKeySetFeatures(parentBuilder.getFeatures()))
             .named(parentBuilder.getName() + " keys")
             .suppressing(parentBuilder.getSuppressedTests())
+            .withSetUp(parentBuilder.getSetUp())
+            .withTearDown(parentBuilder.getTearDown())
             .createTestSuite());
 
     derivedSuites.add(
@@ -125,6 +131,8 @@ protected List<TestSuite> createDerivedSuites(
             .named(parentBuilder.getName() + " values")
             .withFeatures(computeValuesCollectionFeatures(parentBuilder.getFeatures()))
             .suppressing(parentBuilder.getSuppressedTests())
+            .withSetUp(parentBuilder.getSetUp())
+            .withTearDown(parentBuilder.getTearDown())
             .createTestSuite());
 
     return derivedSuites;
diff --git a/android/guava-testlib/src/com/google/common/collect/testing/MinimalCollection.java b/android/guava-testlib/src/com/google/common/collect/testing/MinimalCollection.java
index a6ec93d1eca3..2adf0725147d 100644
--- a/android/guava-testlib/src/com/google/common/collect/testing/MinimalCollection.java
+++ b/android/guava-testlib/src/com/google/common/collect/testing/MinimalCollection.java
@@ -33,12 +33,12 @@ public class MinimalCollection<E> extends AbstractCollection<E> {
   // TODO: expose allow nulls parameter?
 
   public static <E> MinimalCollection<E> of(E... contents) {
-    return new MinimalCollection<E>(Object.class, true, contents);
+    return new MinimalCollection<>(Object.class, true, contents);
   }
 
   // TODO: use this
   public static <E> MinimalCollection<E> ofClassAndContents(Class<? super E> type, E... contents) {
-    return new MinimalCollection<E>(type, true, contents);
+    return new MinimalCollection<>(type, true, contents);
   }
 
   private final E[] contents;
diff --git a/android/guava-testlib/src/com/google/common/collect/testing/MinimalIterable.java b/android/guava-testlib/src/com/google/common/collect/testing/MinimalIterable.java
index c151c15e1319..15d48dbbd75b 100644
--- a/android/guava-testlib/src/com/google/common/collect/testing/MinimalIterable.java
+++ b/android/guava-testlib/src/com/google/common/collect/testing/MinimalIterable.java
@@ -51,7 +51,7 @@ public final class MinimalIterable<E> implements Iterable<E> {
   /** Returns an iterable whose iterator returns the given elements in order. */
   public static <E> MinimalIterable<E> of(E... elements) {
     // Make sure to get an unmodifiable iterator
-    return new MinimalIterable<E>(Arrays.asList(elements).iterator());
+    return new MinimalIterable<>(Arrays.asList(elements).iterator());
   }
 
   /**
@@ -59,7 +59,7 @@ public static <E> MinimalIterable<E> of(E... elements) {
    * out of the source collection at the time this method is called.
    */
   @SuppressWarnings("unchecked") // Es come in, Es go out
-  public static <E> MinimalIterable<E> from(final Collection<E> elements) {
+  public static <E> MinimalIterable<E> from(Collection<E> elements) {
     return (MinimalIterable) of(elements.toArray());
   }
 
diff --git a/android/guava-testlib/src/com/google/common/collect/testing/MinimalSet.java b/android/guava-testlib/src/com/google/common/collect/testing/MinimalSet.java
index 988dd3f95511..9a87d244d01f 100644
--- a/android/guava-testlib/src/com/google/common/collect/testing/MinimalSet.java
+++ b/android/guava-testlib/src/com/google/common/collect/testing/MinimalSet.java
@@ -45,13 +45,13 @@ public static <E> MinimalSet<E> from(Collection<? extends E> contents) {
 
   public static <E> MinimalSet<E> ofClassAndContents(
       Class<? super E> type, E[] emptyArrayForContents, Iterable<? extends E> contents) {
-    List<E> setContents = new ArrayList<E>();
+    List<E> setContents = new ArrayList<>();
     for (E e : contents) {
       if (!setContents.contains(e)) {
         setContents.add(e);
       }
     }
-    return new MinimalSet<E>(type, setContents.toArray(emptyArrayForContents));
+    return new MinimalSet<>(type, setContents.toArray(emptyArrayForContents));
   }
 
   private MinimalSet(Class<? super E> type, E... contents) {
diff --git a/android/guava-testlib/src/com/google/common/collect/testing/NavigableMapTestSuiteBuilder.java b/android/guava-testlib/src/com/google/common/collect/testing/NavigableMapTestSuiteBuilder.java
index 77a198454bd8..0e1a229208e8 100644
--- a/android/guava-testlib/src/com/google/common/collect/testing/NavigableMapTestSuiteBuilder.java
+++ b/android/guava-testlib/src/com/google/common/collect/testing/NavigableMapTestSuiteBuilder.java
@@ -116,10 +116,10 @@ public NavigableMapTestSuiteBuilder<K, V> newBuilderUsing(
 
   /** Create a suite whose maps are descending views of other maps. */
   private TestSuite createDescendingSuite(
-      final FeatureSpecificTestSuiteBuilder<
+      FeatureSpecificTestSuiteBuilder<
               ?, ? extends OneSizeTestContainerGenerator<Map<K, V>, Entry<K, V>>>
           parentBuilder) {
-    final TestSortedMapGenerator<K, V> delegate =
+    TestSortedMapGenerator<K, V> delegate =
         (TestSortedMapGenerator<K, V>) parentBuilder.getSubjectGenerator().getInnerGenerator();
 
     List<Feature<?>> features = new ArrayList<>();
diff --git a/android/guava-testlib/src/com/google/common/collect/testing/NavigableSetTestSuiteBuilder.java b/android/guava-testlib/src/com/google/common/collect/testing/NavigableSetTestSuiteBuilder.java
index 38eb56e09dee..4c86ab46206c 100644
--- a/android/guava-testlib/src/com/google/common/collect/testing/NavigableSetTestSuiteBuilder.java
+++ b/android/guava-testlib/src/com/google/common/collect/testing/NavigableSetTestSuiteBuilder.java
@@ -40,7 +40,7 @@
 @GwtIncompatible
 public final class NavigableSetTestSuiteBuilder<E> extends SortedSetTestSuiteBuilder<E> {
   public static <E> NavigableSetTestSuiteBuilder<E> using(TestSortedSetGenerator<E> generator) {
-    NavigableSetTestSuiteBuilder<E> builder = new NavigableSetTestSuiteBuilder<E>();
+    NavigableSetTestSuiteBuilder<E> builder = new NavigableSetTestSuiteBuilder<>();
     builder.usingGenerator(generator);
     return builder;
   }
@@ -99,10 +99,9 @@ public NavigableSetTestSuiteBuilder<E> newBuilderUsing(
 
   /** Create a suite whose maps are descending views of other maps. */
   private TestSuite createDescendingSuite(
-      final FeatureSpecificTestSuiteBuilder<
-              ?, ? extends OneSizeTestContainerGenerator<Collection<E>, E>>
+      FeatureSpecificTestSuiteBuilder<?, ? extends OneSizeTestContainerGenerator<Collection<E>, E>>
           parentBuilder) {
-    final TestSetGenerator<E> delegate =
+    TestSetGenerator<E> delegate =
         (TestSetGenerator<E>) parentBuilder.getSubjectGenerator().getInnerGenerator();
 
     List<Feature<?>> features = new ArrayList<>();
@@ -124,7 +123,7 @@ public E[] createArray(int length) {
 
               @Override
               public Iterable<E> order(List<E> insertionOrder) {
-                List<E> list = new ArrayList<E>();
+                List<E> list = new ArrayList<>();
                 for (E e : delegate.order(insertionOrder)) {
                   list.add(e);
                 }
diff --git a/android/guava-testlib/src/com/google/common/collect/testing/OneSizeGenerator.java b/android/guava-testlib/src/com/google/common/collect/testing/OneSizeGenerator.java
index 1b8924c07606..1ff3facc4fd4 100644
--- a/android/guava-testlib/src/com/google/common/collect/testing/OneSizeGenerator.java
+++ b/android/guava-testlib/src/com/google/common/collect/testing/OneSizeGenerator.java
@@ -70,7 +70,7 @@ public Collection<E> getSampleElements(int howMany) {
     @SuppressWarnings("unchecked")
     List<E> allSampleElements =
         Arrays.asList(samples.e0(), samples.e1(), samples.e2(), samples.e3(), samples.e4());
-    return new ArrayList<E>(allSampleElements.subList(0, howMany));
+    return new ArrayList<>(allSampleElements.subList(0, howMany));
   }
 
   @Override
diff --git a/android/guava-testlib/src/com/google/common/collect/testing/ReserializingTestCollectionGenerator.java b/android/guava-testlib/src/com/google/common/collect/testing/ReserializingTestCollectionGenerator.java
index 28d6f7917dd9..923f56fd45c0 100644
--- a/android/guava-testlib/src/com/google/common/collect/testing/ReserializingTestCollectionGenerator.java
+++ b/android/guava-testlib/src/com/google/common/collect/testing/ReserializingTestCollectionGenerator.java
@@ -42,7 +42,7 @@ public class ReserializingTestCollectionGenerator<E> implements TestCollectionGe
 
   public static <E> ReserializingTestCollectionGenerator<E> newInstance(
       TestCollectionGenerator<E> delegate) {
-    return new ReserializingTestCollectionGenerator<E>(delegate);
+    return new ReserializingTestCollectionGenerator<>(delegate);
   }
 
   @Override
diff --git a/android/guava-testlib/src/com/google/common/collect/testing/ReserializingTestSetGenerator.java b/android/guava-testlib/src/com/google/common/collect/testing/ReserializingTestSetGenerator.java
index c92a3ff20aca..555440adc172 100644
--- a/android/guava-testlib/src/com/google/common/collect/testing/ReserializingTestSetGenerator.java
+++ b/android/guava-testlib/src/com/google/common/collect/testing/ReserializingTestSetGenerator.java
@@ -35,7 +35,7 @@ public class ReserializingTestSetGenerator<E> extends ReserializingTestCollectio
   }
 
   public static <E> TestSetGenerator<E> newInstance(TestSetGenerator<E> delegate) {
-    return new ReserializingTestSetGenerator<E>(delegate);
+    return new ReserializingTestSetGenerator<>(delegate);
   }
 
   @Override
diff --git a/android/guava-testlib/src/com/google/common/collect/testing/SafeTreeSet.java b/android/guava-testlib/src/com/google/common/collect/testing/SafeTreeSet.java
index 8ed48107347c..91d9fd9f750d 100644
--- a/android/guava-testlib/src/com/google/common/collect/testing/SafeTreeSet.java
+++ b/android/guava-testlib/src/com/google/common/collect/testing/SafeTreeSet.java
@@ -117,7 +117,7 @@ public Iterator<E> descendingIterator() {
 
   @Override
   public NavigableSet<E> descendingSet() {
-    return new SafeTreeSet<E>(delegate.descendingSet());
+    return new SafeTreeSet<>(delegate.descendingSet());
   }
 
   @Override
@@ -137,7 +137,7 @@ public SortedSet<E> headSet(E toElement) {
 
   @Override
   public NavigableSet<E> headSet(E toElement, boolean inclusive) {
-    return new SafeTreeSet<E>(delegate.headSet(checkValid(toElement), inclusive));
+    return new SafeTreeSet<>(delegate.headSet(checkValid(toElement), inclusive));
   }
 
   @Override
@@ -198,7 +198,7 @@ public int size() {
   @Override
   public NavigableSet<E> subSet(
       E fromElement, boolean fromInclusive, E toElement, boolean toInclusive) {
-    return new SafeTreeSet<E>(
+    return new SafeTreeSet<>(
         delegate.subSet(
             checkValid(fromElement), fromInclusive, checkValid(toElement), toInclusive));
   }
@@ -215,7 +215,7 @@ public SortedSet<E> tailSet(E fromElement) {
 
   @Override
   public NavigableSet<E> tailSet(E fromElement, boolean inclusive) {
-    return new SafeTreeSet<E>(delegate.tailSet(checkValid(fromElement), inclusive));
+    return new SafeTreeSet<>(delegate.tailSet(checkValid(fromElement), inclusive));
   }
 
   @Override
diff --git a/android/guava-testlib/src/com/google/common/collect/testing/SetTestSuiteBuilder.java b/android/guava-testlib/src/com/google/common/collect/testing/SetTestSuiteBuilder.java
index 26a2870ca9d5..4ac51a4612f1 100644
--- a/android/guava-testlib/src/com/google/common/collect/testing/SetTestSuiteBuilder.java
+++ b/android/guava-testlib/src/com/google/common/collect/testing/SetTestSuiteBuilder.java
@@ -78,6 +78,8 @@ protected List<TestSuite> createDerivedSuites(
               .named(getName() + " reserialized")
               .withFeatures(computeReserializedCollectionFeatures(parentBuilder.getFeatures()))
               .suppressing(parentBuilder.getSuppressedTests())
+              .withSetUp(parentBuilder.getSetUp())
+              .withTearDown(parentBuilder.getTearDown())
               .createTestSuite());
     }
     return derivedSuites;
diff --git a/android/guava-testlib/src/com/google/common/collect/testing/SortedMapInterfaceTest.java b/android/guava-testlib/src/com/google/common/collect/testing/SortedMapInterfaceTest.java
index 829c4cc27874..03266ab4776d 100644
--- a/android/guava-testlib/src/com/google/common/collect/testing/SortedMapInterfaceTest.java
+++ b/android/guava-testlib/src/com/google/common/collect/testing/SortedMapInterfaceTest.java
@@ -56,7 +56,7 @@ protected SortedMap<K, V> makeEitherMap() {
   }
 
   public void testTailMapWriteThrough() {
-    final SortedMap<K, V> map;
+    SortedMap<K, V> map;
     try {
       map = makePopulatedMap();
     } catch (UnsupportedOperationException e) {
@@ -82,7 +82,7 @@ public void testTailMapWriteThrough() {
   }
 
   public void testTailMapRemoveThrough() {
-    final SortedMap<K, V> map;
+    SortedMap<K, V> map;
     try {
       map = makePopulatedMap();
     } catch (UnsupportedOperationException e) {
@@ -105,7 +105,7 @@ public void testTailMapRemoveThrough() {
   }
 
   public void testTailMapClearThrough() {
-    final SortedMap<K, V> map;
+    SortedMap<K, V> map;
     try {
       map = makePopulatedMap();
     } catch (UnsupportedOperationException e) {
diff --git a/android/guava-testlib/src/com/google/common/collect/testing/SortedMapTestSuiteBuilder.java b/android/guava-testlib/src/com/google/common/collect/testing/SortedMapTestSuiteBuilder.java
index e95383af64a6..7944aaa6a0b8 100644
--- a/android/guava-testlib/src/com/google/common/collect/testing/SortedMapTestSuiteBuilder.java
+++ b/android/guava-testlib/src/com/google/common/collect/testing/SortedMapTestSuiteBuilder.java
@@ -105,12 +105,12 @@ public Set<Feature<? super Void>> getImpliedFeatures() {
    * these extreme values rather than relying on their regular sort ordering.
    */
   final TestSuite createSubmapSuite(
-      final FeatureSpecificTestSuiteBuilder<
+      FeatureSpecificTestSuiteBuilder<
               ?, ? extends OneSizeTestContainerGenerator<Map<K, V>, Entry<K, V>>>
           parentBuilder,
-      final Bound from,
-      final Bound to) {
-    final TestSortedMapGenerator<K, V> delegate =
+      Bound from,
+      Bound to) {
+    TestSortedMapGenerator<K, V> delegate =
         (TestSortedMapGenerator<K, V>) parentBuilder.getSubjectGenerator().getInnerGenerator();
 
     List<Feature<?>> features = new ArrayList<>();
@@ -121,6 +121,8 @@ final TestSuite createSubmapSuite(
         .named(parentBuilder.getName() + " subMap " + from + "-" + to)
         .withFeatures(features)
         .suppressing(parentBuilder.getSuppressedTests())
+        .withSetUp(parentBuilder.getSetUp())
+        .withTearDown(parentBuilder.getTearDown())
         .createTestSuite();
   }
 
diff --git a/android/guava-testlib/src/com/google/common/collect/testing/SortedSetTestSuiteBuilder.java b/android/guava-testlib/src/com/google/common/collect/testing/SortedSetTestSuiteBuilder.java
index e97b08fc5537..2835769e33f7 100644
--- a/android/guava-testlib/src/com/google/common/collect/testing/SortedSetTestSuiteBuilder.java
+++ b/android/guava-testlib/src/com/google/common/collect/testing/SortedSetTestSuiteBuilder.java
@@ -34,7 +34,7 @@
 @GwtIncompatible
 public class SortedSetTestSuiteBuilder<E> extends SetTestSuiteBuilder<E> {
   public static <E> SortedSetTestSuiteBuilder<E> using(TestSortedSetGenerator<E> generator) {
-    SortedSetTestSuiteBuilder<E> builder = new SortedSetTestSuiteBuilder<E>();
+    SortedSetTestSuiteBuilder<E> builder = new SortedSetTestSuiteBuilder<>();
     builder.usingGenerator(generator);
     return builder;
   }
@@ -78,12 +78,11 @@ protected List<TestSuite> createDerivedSuites(
    * these extreme values rather than relying on their regular sort ordering.
    */
   final TestSuite createSubsetSuite(
-      final FeatureSpecificTestSuiteBuilder<
-              ?, ? extends OneSizeTestContainerGenerator<Collection<E>, E>>
+      FeatureSpecificTestSuiteBuilder<?, ? extends OneSizeTestContainerGenerator<Collection<E>, E>>
           parentBuilder,
-      final Bound from,
-      final Bound to) {
-    final TestSortedSetGenerator<E> delegate =
+      Bound from,
+      Bound to) {
+    TestSortedSetGenerator<E> delegate =
         (TestSortedSetGenerator<E>) parentBuilder.getSubjectGenerator().getInnerGenerator();
 
     List<Feature<?>> features = new ArrayList<>(parentBuilder.getFeatures());
@@ -94,6 +93,8 @@ final TestSuite createSubsetSuite(
         .named(parentBuilder.getName() + " subSet " + from + "-" + to)
         .withFeatures(features)
         .suppressing(parentBuilder.getSuppressedTests())
+        .withSetUp(parentBuilder.getSetUp())
+        .withTearDown(parentBuilder.getTearDown())
         .createTestSuite();
   }
 
diff --git a/android/guava-testlib/src/com/google/common/collect/testing/features/FeatureUtil.java b/android/guava-testlib/src/com/google/common/collect/testing/features/FeatureUtil.java
index 95cbc0b3d8be..2d11a0863494 100644
--- a/android/guava-testlib/src/com/google/common/collect/testing/features/FeatureUtil.java
+++ b/android/guava-testlib/src/com/google/common/collect/testing/features/FeatureUtil.java
@@ -139,12 +139,12 @@ public static TesterRequirements getTesterRequirements(Method testerMethod)
    */
   static TesterRequirements buildTesterRequirements(Class<?> testerClass)
       throws ConflictingRequirementsException {
-    final TesterRequirements declaredRequirements = buildDeclaredTesterRequirements(testerClass);
+    TesterRequirements declaredRequirements = buildDeclaredTesterRequirements(testerClass);
     Class<?> baseClass = testerClass.getSuperclass();
     if (baseClass == null) {
       return declaredRequirements;
     } else {
-      final TesterRequirements clonedBaseRequirements =
+      TesterRequirements clonedBaseRequirements =
           new TesterRequirements(getTesterRequirements(baseClass));
       return incorporateRequirements(clonedBaseRequirements, declaredRequirements, testerClass);
     }
@@ -176,8 +176,8 @@ static TesterRequirements buildTesterRequirements(Method testerMethod)
   private static TesterRequirements buildTesterRequirements(Annotation testerAnnotation)
       throws ConflictingRequirementsException {
     Class<? extends Annotation> annotationClass = testerAnnotation.annotationType();
-    final Feature<?>[] presentFeatures;
-    final Feature<?>[] absentFeatures;
+    Feature<?>[] presentFeatures;
+    Feature<?>[] absentFeatures;
     try {
       presentFeatures = (Feature[]) annotationClass.getMethod("value").invoke(testerAnnotation);
       absentFeatures = (Feature[]) annotationClass.getMethod("absent").invoke(testerAnnotation);
diff --git a/android/guava-testlib/src/com/google/common/collect/testing/google/AbstractMultimapTester.java b/android/guava-testlib/src/com/google/common/collect/testing/google/AbstractMultimapTester.java
index 7b7801db2633..7f649e757165 100644
--- a/android/guava-testlib/src/com/google/common/collect/testing/google/AbstractMultimapTester.java
+++ b/android/guava-testlib/src/com/google/common/collect/testing/google/AbstractMultimapTester.java
@@ -48,8 +48,8 @@ protected M multimap() {
   /** @return an array of the proper size with {@code null} as the key of the middle element. */
   protected Entry<K, V>[] createArrayWithNullKey() {
     Entry<K, V>[] array = createSamplesArray();
-    final int nullKeyLocation = getNullLocation();
-    final Entry<K, V> oldEntry = array[nullKeyLocation];
+    int nullKeyLocation = getNullLocation();
+    Entry<K, V> oldEntry = array[nullKeyLocation];
     array[nullKeyLocation] = Helpers.mapEntry(null, oldEntry.getValue());
     return array;
   }
@@ -57,8 +57,8 @@ protected Entry<K, V>[] createArrayWithNullKey() {
   /** @return an array of the proper size with {@code null} as the value of the middle element. */
   protected Entry<K, V>[] createArrayWithNullValue() {
     Entry<K, V>[] array = createSamplesArray();
-    final int nullValueLocation = getNullLocation();
-    final Entry<K, V> oldEntry = array[nullValueLocation];
+    int nullValueLocation = getNullLocation();
+    Entry<K, V> oldEntry = array[nullValueLocation];
     array[nullValueLocation] = Helpers.mapEntry(oldEntry.getKey(), null);
     return array;
   }
@@ -69,7 +69,7 @@ protected Entry<K, V>[] createArrayWithNullValue() {
    */
   protected Entry<K, V>[] createArrayWithNullKeyAndValue() {
     Entry<K, V>[] array = createSamplesArray();
-    final int nullValueLocation = getNullLocation();
+    int nullValueLocation = getNullLocation();
     array[nullValueLocation] = Helpers.mapEntry(null, null);
     return array;
   }
diff --git a/android/guava-testlib/src/com/google/common/collect/testing/google/BiMapTestSuiteBuilder.java b/android/guava-testlib/src/com/google/common/collect/testing/google/BiMapTestSuiteBuilder.java
index fa21a71a536d..0821fb0b554e 100644
--- a/android/guava-testlib/src/com/google/common/collect/testing/google/BiMapTestSuiteBuilder.java
+++ b/android/guava-testlib/src/com/google/common/collect/testing/google/BiMapTestSuiteBuilder.java
@@ -88,6 +88,8 @@ protected List<TestSuite> createDerivedSuites(
             .suppressing(parentBuilder.getSuppressedTests())
             .suppressing(SetCreationTester.class.getMethods())
             // BiMap.entrySet() duplicate-handling behavior is too confusing for SetCreationTester
+            .withSetUp(parentBuilder.getSetUp())
+            .withTearDown(parentBuilder.getTearDown())
             .createTestSuite());
     /*
      * TODO(cpovirk): the Map tests duplicate most of this effort by using a
@@ -101,6 +103,8 @@ protected List<TestSuite> createDerivedSuites(
             .suppressing(parentBuilder.getSuppressedTests())
             .suppressing(SetCreationTester.class.getMethods())
             // BiMap.values() duplicate-handling behavior is too confusing for SetCreationTester
+            .withSetUp(parentBuilder.getSetUp())
+            .withTearDown(parentBuilder.getTearDown())
             .createTestSuite());
     if (!parentBuilder.getFeatures().contains(NoRecurse.INVERSE)) {
       derived.add(
@@ -109,6 +113,8 @@ protected List<TestSuite> createDerivedSuites(
               .withFeatures(computeInverseFeatures(parentBuilder.getFeatures()))
               .named(parentBuilder.getName() + " inverse")
               .suppressing(parentBuilder.getSuppressedTests())
+              .withSetUp(parentBuilder.getSetUp())
+              .withTearDown(parentBuilder.getTearDown())
               .createTestSuite());
     }
 
diff --git a/android/guava-testlib/src/com/google/common/collect/testing/google/DerivedGoogleCollectionGenerators.java b/android/guava-testlib/src/com/google/common/collect/testing/google/DerivedGoogleCollectionGenerators.java
index bbeefd278e00..35579a01d758 100644
--- a/android/guava-testlib/src/com/google/common/collect/testing/google/DerivedGoogleCollectionGenerators.java
+++ b/android/guava-testlib/src/com/google/common/collect/testing/google/DerivedGoogleCollectionGenerators.java
@@ -159,9 +159,9 @@ public static class BiMapValueSetGenerator<K, V>
     public BiMapValueSetGenerator(
         OneSizeTestContainerGenerator<BiMap<K, V>, Entry<K, V>> mapGenerator) {
       this.mapGenerator = mapGenerator;
-      final SampleElements<Entry<K, V>> mapSamples = this.mapGenerator.samples();
+      SampleElements<Entry<K, V>> mapSamples = this.mapGenerator.samples();
       this.samples =
-          new SampleElements<V>(
+          new SampleElements<>(
               mapSamples.e0().getValue(),
               mapSamples.e1().getValue(),
               mapSamples.e2().getValue(),
@@ -194,7 +194,7 @@ public Set<V> create(Object... elements) {
 
     @Override
     public V[] createArray(int length) {
-      final V[] vs =
+      V[] vs =
           ((TestBiMapGenerator<K, V>) mapGenerator.getInnerGenerator()).createValueArray(length);
       return vs;
     }
diff --git a/android/guava-testlib/src/com/google/common/collect/testing/google/MapGenerators.java b/android/guava-testlib/src/com/google/common/collect/testing/google/MapGenerators.java
index bb84ea15f931..35063e815d0b 100644
--- a/android/guava-testlib/src/com/google/common/collect/testing/google/MapGenerators.java
+++ b/android/guava-testlib/src/com/google/common/collect/testing/google/MapGenerators.java
@@ -54,7 +54,7 @@ protected Map<String, String> create(Entry<String, String>[] entries) {
       for (Entry<String, String> entry : entries) {
         builder.put(entry.getKey(), entry.getValue());
       }
-      return builder.build();
+      return builder.buildOrThrow();
     }
   }
 
@@ -86,7 +86,7 @@ public Collection<UnhashableObject> create(UnhashableObject[] elements) {
       for (UnhashableObject value : elements) {
         builder.put(key++, value);
       }
-      return builder.build().values();
+      return builder.buildOrThrow().values();
     }
   }
 
@@ -97,7 +97,7 @@ public List<String> create(String[] elements) {
       for (int i = 0; i < elements.length; i++) {
         builder.put(elements[i], i);
       }
-      return builder.build().keySet().asList();
+      return builder.buildOrThrow().keySet().asList();
     }
   }
 
@@ -108,7 +108,7 @@ public List<String> create(String[] elements) {
       for (int i = 0; i < elements.length; i++) {
         builder.put(i, elements[i]);
       }
-      return builder.build().values().asList();
+      return builder.buildOrThrow().values().asList();
     }
   }
 
@@ -144,7 +144,7 @@ public List<Entry<String, Integer>> create(Object... elements) {
         Entry<String, Integer> entry = (Entry<String, Integer>) o;
         builder.put(entry);
       }
-      return builder.build().entrySet().asList();
+      return builder.buildOrThrow().entrySet().asList();
     }
   }
 
@@ -210,7 +210,7 @@ public Map<String, Collection<Integer>> create(Object... elements) {
         Integer value = Iterables.getOnlyElement(entry.getValue());
         builder.put(entry.getKey(), value);
       }
-      return builder.build().asMultimap().asMap();
+      return builder.buildOrThrow().asMultimap().asMap();
     }
 
     @Override
diff --git a/android/guava-testlib/src/com/google/common/collect/testing/google/MultimapTestSuiteBuilder.java b/android/guava-testlib/src/com/google/common/collect/testing/google/MultimapTestSuiteBuilder.java
index 8504940bb6fb..97c24c98d277 100644
--- a/android/guava-testlib/src/com/google/common/collect/testing/google/MultimapTestSuiteBuilder.java
+++ b/android/guava-testlib/src/com/google/common/collect/testing/google/MultimapTestSuiteBuilder.java
@@ -115,6 +115,8 @@ protected List<TestSuite> createDerivedSuites(
               .withFeatures(computeReserializedMultimapFeatures(parentBuilder.getFeatures()))
               .named(parentBuilder.getName() + " reserialized")
               .suppressing(parentBuilder.getSuppressedTests())
+              .withSetUp(parentBuilder.getSetUp())
+              .withTearDown(parentBuilder.getTearDown())
               .createTestSuite());
     }
 
@@ -123,6 +125,8 @@ protected List<TestSuite> createDerivedSuites(
             .withFeatures(computeAsMapFeatures(parentBuilder.getFeatures()))
             .named(parentBuilder.getName() + ".asMap")
             .suppressing(parentBuilder.getSuppressedTests())
+            .withSetUp(parentBuilder.getSetUp())
+            .withTearDown(parentBuilder.getTearDown())
             .createTestSuite());
 
     derivedSuites.add(computeEntriesTestSuite(parentBuilder));
@@ -153,6 +157,8 @@ TestSuite computeEntriesTestSuite(
         .withFeatures(computeEntriesFeatures(parentBuilder.getFeatures()))
         .named(parentBuilder.getName() + ".entries")
         .suppressing(parentBuilder.getSuppressedTests())
+        .withSetUp(parentBuilder.getSetUp())
+        .withTearDown(parentBuilder.getTearDown())
         .createTestSuite();
   }
 
@@ -164,6 +170,8 @@ TestSuite computeMultimapGetTestSuite(
         .withFeatures(computeMultimapGetFeatures(parentBuilder.getFeatures()))
         .named(parentBuilder.getName() + ".get[key]")
         .suppressing(parentBuilder.getSuppressedTests())
+        .withSetUp(parentBuilder.getSetUp())
+        .withTearDown(parentBuilder.getTearDown())
         .createTestSuite();
   }
 
@@ -179,6 +187,8 @@ TestSuite computeMultimapAsMapGetTestSuite(
           .withFeatures(features)
           .named(parentBuilder.getName() + ".asMap[].get[key]")
           .suppressing(parentBuilder.getSuppressedTests())
+          .withSetUp(parentBuilder.getSetUp())
+          .withTearDown(parentBuilder.getTearDown())
           .createTestSuite();
     }
   }
@@ -191,6 +201,8 @@ TestSuite computeKeysTestSuite(
         .withFeatures(computeKeysFeatures(parentBuilder.getFeatures()))
         .named(parentBuilder.getName() + ".keys")
         .suppressing(parentBuilder.getSuppressedTests())
+        .withSetUp(parentBuilder.getSetUp())
+        .withTearDown(parentBuilder.getTearDown())
         .createTestSuite();
   }
 
diff --git a/android/guava-testlib/src/com/google/common/collect/testing/google/MultisetNavigationTester.java b/android/guava-testlib/src/com/google/common/collect/testing/google/MultisetNavigationTester.java
index b65cd967ac0d..ce8e283a9c3e 100644
--- a/android/guava-testlib/src/com/google/common/collect/testing/google/MultisetNavigationTester.java
+++ b/android/guava-testlib/src/com/google/common/collect/testing/google/MultisetNavigationTester.java
@@ -82,7 +82,7 @@ public void setUp() throws Exception {
   @SuppressWarnings("unchecked")
   // Needed to stop Eclipse whining
   private void resetWithHole() {
-    List<E> container = new ArrayList<E>();
+    List<E> container = new ArrayList<>();
     container.addAll(Collections.nCopies(a.getCount(), a.getElement()));
     container.addAll(Collections.nCopies(c.getCount(), c.getElement()));
     super.resetContainer(getSubjectGenerator().create(container.toArray()));
diff --git a/android/guava-testlib/src/com/google/common/collect/testing/google/MultisetTestSuiteBuilder.java b/android/guava-testlib/src/com/google/common/collect/testing/google/MultisetTestSuiteBuilder.java
index 266daa4621b1..d6a665c14bd4 100644
--- a/android/guava-testlib/src/com/google/common/collect/testing/google/MultisetTestSuiteBuilder.java
+++ b/android/guava-testlib/src/com/google/common/collect/testing/google/MultisetTestSuiteBuilder.java
@@ -130,6 +130,8 @@ protected List<TestSuite> createDerivedSuites(
               .named(getName() + ".entrySet")
               .withFeatures(computeEntrySetFeatures(parentBuilder.getFeatures()))
               .suppressing(parentBuilder.getSuppressedTests())
+              .withSetUp(parentBuilder.getSetUp())
+              .withTearDown(parentBuilder.getTearDown())
               .createTestSuite());
     }
 
@@ -140,6 +142,8 @@ protected List<TestSuite> createDerivedSuites(
               .named(getName() + " reserialized")
               .withFeatures(computeReserializedMultisetFeatures(parentBuilder.getFeatures()))
               .suppressing(parentBuilder.getSuppressedTests())
+              .withSetUp(parentBuilder.getSetUp())
+              .withTearDown(parentBuilder.getTearDown())
               .createTestSuite());
     }
     return derivedSuites;
@@ -153,6 +157,8 @@ TestSuite createElementSetTestSuite(
         .named(getName() + ".elementSet")
         .withFeatures(computeElementSetFeatures(parentBuilder.getFeatures()))
         .suppressing(parentBuilder.getSuppressedTests())
+        .withSetUp(parentBuilder.getSetUp())
+        .withTearDown(parentBuilder.getTearDown())
         .createTestSuite();
   }
 
diff --git a/android/guava-testlib/src/com/google/common/collect/testing/google/SetMultimapAsMapTester.java b/android/guava-testlib/src/com/google/common/collect/testing/google/SetMultimapAsMapTester.java
index 49187dd1dffe..6e7995720846 100644
--- a/android/guava-testlib/src/com/google/common/collect/testing/google/SetMultimapAsMapTester.java
+++ b/android/guava-testlib/src/com/google/common/collect/testing/google/SetMultimapAsMapTester.java
@@ -58,7 +58,7 @@ public void testAsMapGetImplementsSet() {
 
   @MapFeature.Require(SUPPORTS_REMOVE)
   public void testAsMapRemoveImplementsSet() {
-    List<K> keys = new ArrayList<K>(multimap().keySet());
+    List<K> keys = new ArrayList<>(multimap().keySet());
     for (K key : keys) {
       resetCollection();
       assertTrue(multimap().asMap().remove(key) instanceof Set);
diff --git a/android/guava-testlib/src/com/google/common/collect/testing/google/SortedMultisetTestSuiteBuilder.java b/android/guava-testlib/src/com/google/common/collect/testing/google/SortedMultisetTestSuiteBuilder.java
index dafd52187df4..b44494b81ddf 100644
--- a/android/guava-testlib/src/com/google/common/collect/testing/google/SortedMultisetTestSuiteBuilder.java
+++ b/android/guava-testlib/src/com/google/common/collect/testing/google/SortedMultisetTestSuiteBuilder.java
@@ -56,7 +56,7 @@
 @GwtIncompatible
 public class SortedMultisetTestSuiteBuilder<E> extends MultisetTestSuiteBuilder<E> {
   public static <E> SortedMultisetTestSuiteBuilder<E> using(TestMultisetGenerator<E> generator) {
-    SortedMultisetTestSuiteBuilder<E> result = new SortedMultisetTestSuiteBuilder<E>();
+    SortedMultisetTestSuiteBuilder<E> result = new SortedMultisetTestSuiteBuilder<>();
     result.usingGenerator(generator);
     return result;
   }
@@ -138,8 +138,8 @@ List<TestSuite> createDerivedSuites(SortedMultisetTestSuiteBuilder<E> parentBuil
   }
 
   private TestSuite createSubMultisetSuite(
-      SortedMultisetTestSuiteBuilder<E> parentBuilder, final Bound from, final Bound to) {
-    final TestMultisetGenerator<E> delegate =
+      SortedMultisetTestSuiteBuilder<E> parentBuilder, Bound from, Bound to) {
+    TestMultisetGenerator<E> delegate =
         (TestMultisetGenerator<E>) parentBuilder.getSubjectGenerator();
 
     Set<Feature<?>> features = new HashSet<>();
@@ -152,15 +152,15 @@ private TestSuite createSubMultisetSuite(
     }
 
     SortedMultiset<E> emptyMultiset = (SortedMultiset<E>) delegate.create();
-    final Comparator<? super E> comparator = emptyMultiset.comparator();
+    Comparator<? super E> comparator = emptyMultiset.comparator();
     SampleElements<E> samples = delegate.samples();
     @SuppressWarnings("unchecked")
     List<E> samplesList =
         Arrays.asList(samples.e0(), samples.e1(), samples.e2(), samples.e3(), samples.e4());
 
     Collections.sort(samplesList, comparator);
-    final E firstInclusive = samplesList.get(0);
-    final E lastInclusive = samplesList.get(samplesList.size() - 1);
+    E firstInclusive = samplesList.get(0);
+    E lastInclusive = samplesList.get(samplesList.size() - 1);
 
     return SortedMultisetTestSuiteBuilder.using(
             new ForwardingTestMultisetGenerator<E>(delegate) {
@@ -187,7 +187,7 @@ public SortedMultiset<E> create(Object... entries) {
                 }
 
                 // the regular values should be visible after filtering
-                List<E> allEntries = new ArrayList<E>();
+                List<E> allEntries = new ArrayList<>();
                 allEntries.addAll(extremeValues);
                 allEntries.addAll(normalValues);
                 SortedMultiset<E> multiset =
@@ -234,7 +234,7 @@ private List<String> getExtremeValues() {
   }
 
   private TestSuite createDescendingSuite(SortedMultisetTestSuiteBuilder<E> parentBuilder) {
-    final TestMultisetGenerator<E> delegate =
+    TestMultisetGenerator<E> delegate =
         (TestMultisetGenerator<E>) parentBuilder.getSubjectGenerator();
 
     Set<Feature<?>> features = new HashSet<>();
@@ -263,7 +263,7 @@ public Iterable<E> order(List<E> insertionOrder) {
   }
 
   private TestSuite createReserializedSuite(SortedMultisetTestSuiteBuilder<E> parentBuilder) {
-    final TestMultisetGenerator<E> delegate =
+    TestMultisetGenerator<E> delegate =
         (TestMultisetGenerator<E>) parentBuilder.getSubjectGenerator();
 
     Set<Feature<?>> features = new HashSet<>(parentBuilder.getFeatures());
diff --git a/android/guava-testlib/src/com/google/common/collect/testing/google/SortedSetMultimapAsMapTester.java b/android/guava-testlib/src/com/google/common/collect/testing/google/SortedSetMultimapAsMapTester.java
index 1c00f0970102..e95b74f84b0c 100644
--- a/android/guava-testlib/src/com/google/common/collect/testing/google/SortedSetMultimapAsMapTester.java
+++ b/android/guava-testlib/src/com/google/common/collect/testing/google/SortedSetMultimapAsMapTester.java
@@ -52,7 +52,7 @@ public void testAsMapGetImplementsSortedSet() {
 
   @MapFeature.Require(SUPPORTS_REMOVE)
   public void testAsMapRemoveImplementsSortedSet() {
-    List<K> keys = new ArrayList<K>(multimap().keySet());
+    List<K> keys = new ArrayList<>(multimap().keySet());
     for (K key : keys) {
       resetCollection();
       SortedSet<V> valueSet = (SortedSet<V>) multimap().asMap().remove(key);
diff --git a/android/guava-testlib/src/com/google/common/collect/testing/google/UnmodifiableCollectionTests.java b/android/guava-testlib/src/com/google/common/collect/testing/google/UnmodifiableCollectionTests.java
index 005746f4be20..40b2c859d20c 100644
--- a/android/guava-testlib/src/com/google/common/collect/testing/google/UnmodifiableCollectionTests.java
+++ b/android/guava-testlib/src/com/google/common/collect/testing/google/UnmodifiableCollectionTests.java
@@ -201,7 +201,7 @@ public static <E> void assertSetIsUnmodifiable(Set<E> set, E sampleElement) {
    * @param sampleElement an element of the same type as that contained by {@code multiset}. {@code
    *     multiset} may or may not have {@code sampleElement} as a member.
    */
-  public static <E> void assertMultisetIsUnmodifiable(Multiset<E> multiset, final E sampleElement) {
+  public static <E> void assertMultisetIsUnmodifiable(Multiset<E> multiset, E sampleElement) {
     Multiset<E> copy = LinkedHashMultiset.create(multiset);
     assertCollectionsAreEquivalent(multiset, copy);
 
@@ -264,7 +264,7 @@ public E getElement() {
    *     multimap} may or may not have {@code sampleValue} as a key.
    */
   public static <K, V> void assertMultimapIsUnmodifiable(
-      Multimap<K, V> multimap, final K sampleKey, final V sampleValue) {
+      Multimap<K, V> multimap, K sampleKey, V sampleValue) {
     List<Entry<K, V>> originalEntries =
         Collections.unmodifiableList(Lists.newArrayList(multimap.entries()));
 
diff --git a/android/guava-testlib/src/com/google/common/collect/testing/testers/CollectionIteratorTester.java b/android/guava-testlib/src/com/google/common/collect/testing/testers/CollectionIteratorTester.java
index b17049709e81..1699fe19dced 100644
--- a/android/guava-testlib/src/com/google/common/collect/testing/testers/CollectionIteratorTester.java
+++ b/android/guava-testlib/src/com/google/common/collect/testing/testers/CollectionIteratorTester.java
@@ -51,7 +51,7 @@
 @Ignore // Affects only Android test runner, which respects JUnit 4 annotations on JUnit 3 tests.
 public class CollectionIteratorTester<E> extends AbstractCollectionTester<E> {
   public void testIterator() {
-    List<E> iteratorElements = new ArrayList<E>();
+    List<E> iteratorElements = new ArrayList<>();
     for (E element : collection) { // uses iterator()
       iteratorElements.add(element);
     }
@@ -60,7 +60,7 @@ public void testIterator() {
 
   @CollectionFeature.Require(KNOWN_ORDER)
   public void testIterationOrdering() {
-    List<E> iteratorElements = new ArrayList<E>();
+    List<E> iteratorElements = new ArrayList<>();
     for (E element : collection) { // uses iterator()
       iteratorElements.add(element);
     }
@@ -72,7 +72,7 @@ public void testIterationOrdering() {
   @CollectionSize.Require(absent = ZERO)
   public void testIterator_nullElement() {
     initCollectionWithNullElement();
-    List<E> iteratorElements = new ArrayList<E>();
+    List<E> iteratorElements = new ArrayList<>();
     for (E element : collection) { // uses iterator()
       iteratorElements.add(element);
     }
diff --git a/android/guava-testlib/src/com/google/common/collect/testing/testers/CollectionToArrayTester.java b/android/guava-testlib/src/com/google/common/collect/testing/testers/CollectionToArrayTester.java
index 83a4ceac869d..b40fc3636943 100644
--- a/android/guava-testlib/src/com/google/common/collect/testing/testers/CollectionToArrayTester.java
+++ b/android/guava-testlib/src/com/google/common/collect/testing/testers/CollectionToArrayTester.java
@@ -48,8 +48,8 @@ public void testToArray_noArgs() {
   }
 
   /**
-   * {@link Collection#toArray(Object[])} says: "Note that <tt>toArray(new Object[0])</tt> is
-   * identical in function to <tt>toArray()</tt>."
+   * {@link Collection#toArray(Object[])} says: "Note that {@code toArray(new Object[0])} is
+   * identical in function to {@code toArray()}."
    *
    * <p>For maximum effect, the collection under test should be created from an element array of a
    * type other than {@code Object[]}.
diff --git a/android/guava-testlib/src/com/google/common/collect/testing/testers/NavigableSetNavigationTester.java b/android/guava-testlib/src/com/google/common/collect/testing/testers/NavigableSetNavigationTester.java
index 39016169d986..8b056b4cb1a1 100644
--- a/android/guava-testlib/src/com/google/common/collect/testing/testers/NavigableSetNavigationTester.java
+++ b/android/guava-testlib/src/com/google/common/collect/testing/testers/NavigableSetNavigationTester.java
@@ -218,7 +218,7 @@ public void testPollLastUnsupported() {
 
   @CollectionSize.Require(SEVERAL)
   public void testDescendingNavigation() {
-    List<E> descending = new ArrayList<E>();
+    List<E> descending = new ArrayList<>();
     for (Iterator<E> i = navigableSet.descendingIterator(); i.hasNext(); ) {
       descending.add(i.next());
     }
diff --git a/android/guava-testlib/src/com/google/common/escape/testing/EscaperAsserts.java b/android/guava-testlib/src/com/google/common/escape/testing/EscaperAsserts.java
index 3920afe4c137..31ac2015dd04 100644
--- a/android/guava-testlib/src/com/google/common/escape/testing/EscaperAsserts.java
+++ b/android/guava-testlib/src/com/google/common/escape/testing/EscaperAsserts.java
@@ -18,7 +18,6 @@
 
 import static com.google.common.escape.Escapers.computeReplacement;
 
-import com.google.common.annotations.Beta;
 import com.google.common.annotations.GwtCompatible;
 import com.google.common.escape.CharEscaper;
 import com.google.common.escape.Escaper;
@@ -32,7 +31,6 @@
  * @author David Beaumont
  * @since 15.0
  */
-@Beta
 @GwtCompatible
 public final class EscaperAsserts {
   private EscaperAsserts() {}
diff --git a/android/guava-testlib/src/com/google/common/testing/AbstractPackageSanityTests.java b/android/guava-testlib/src/com/google/common/testing/AbstractPackageSanityTests.java
index 962b15f6d677..1e31bbfb408f 100644
--- a/android/guava-testlib/src/com/google/common/testing/AbstractPackageSanityTests.java
+++ b/android/guava-testlib/src/com/google/common/testing/AbstractPackageSanityTests.java
@@ -116,12 +116,7 @@ public abstract class AbstractPackageSanityTests extends TestCase {
    * @since 19.0
    */
   public static final Predicate<Class<?>> UNDERSCORE_IN_NAME =
-      new Predicate<Class<?>>() {
-        @Override
-        public boolean apply(Class<?> c) {
-          return c.getSimpleName().contains("_");
-        }
-      };
+      (Class<?> c) -> c.getSimpleName().contains("_");
 
   /* The names of the expected method that tests null checks. */
   private static final ImmutableList<String> NULL_TEST_METHOD_NAMES =
@@ -152,12 +147,7 @@ public boolean apply(Class<?> c) {
   private final ClassSanityTester tester = new ClassSanityTester();
   private Visibility visibility = Visibility.PACKAGE;
   private Predicate<Class<?>> classFilter =
-      new Predicate<Class<?>>() {
-        @Override
-        public boolean apply(Class<?> cls) {
-          return visibility.isVisible(cls.getModifiers());
-        }
-      };
+      (Class<?> cls) -> visibility.isVisible(cls.getModifiers());
 
   /**
    * Restricts the sanity tests for public API only. By default, package-private API are also
@@ -415,8 +405,8 @@ private static boolean isEqualsDefined(Class<?> cls) {
 
   abstract static class Chopper {
 
-    final Chopper or(final Chopper you) {
-      final Chopper i = this;
+    final Chopper or(Chopper you) {
+      Chopper i = this;
       return new Chopper() {
         @Override
         Optional<String> chop(String str) {
@@ -427,7 +417,7 @@ Optional<String> chop(String str) {
 
     abstract Optional<String> chop(String str);
 
-    static Chopper suffix(final String suffix) {
+    static Chopper suffix(String suffix) {
       return new Chopper() {
         @Override
         Optional<String> chop(String str) {
diff --git a/android/guava-testlib/src/com/google/common/testing/ArbitraryInstances.java b/android/guava-testlib/src/com/google/common/testing/ArbitraryInstances.java
index 01904d6c220c..26f4df4749af 100644
--- a/android/guava-testlib/src/com/google/common/testing/ArbitraryInstances.java
+++ b/android/guava-testlib/src/com/google/common/testing/ArbitraryInstances.java
@@ -18,7 +18,6 @@
 
 import static com.google.common.base.Preconditions.checkArgument;
 
-import com.google.common.annotations.Beta;
 import com.google.common.annotations.GwtIncompatible;
 import com.google.common.base.CharMatcher;
 import com.google.common.base.Charsets;
@@ -74,6 +73,7 @@
 import com.google.common.primitives.Primitives;
 import com.google.common.primitives.UnsignedInteger;
 import com.google.common.primitives.UnsignedLong;
+import com.google.errorprone.annotations.Keep;
 import java.io.ByteArrayInputStream;
 import java.io.ByteArrayOutputStream;
 import java.io.File;
@@ -142,7 +142,7 @@
 import java.util.regex.MatchResult;
 import java.util.regex.Matcher;
 import java.util.regex.Pattern;
-import org.checkerframework.checker.nullness.compatqual.NullableDecl;
+import javax.annotation.CheckForNull;
 
 /**
  * Supplies an arbitrary "default" instance for a wide range of types, often useful in testing
@@ -166,7 +166,6 @@
  * @author Ben Yu
  * @since 12.0
  */
-@Beta
 @GwtIncompatible
 public final class ArbitraryInstances {
 
@@ -327,7 +326,7 @@ private static <T> void setImplementation(Class<T> type, Class<? extends T> impl
   }
 
   @SuppressWarnings("unchecked") // it's a subtype map
-  @NullableDecl
+  @CheckForNull
   private static <T> Class<? extends T> getImplementation(Class<T> type) {
     return (Class<? extends T>) implementations.get(type);
   }
@@ -338,7 +337,7 @@ private static <T> Class<? extends T> getImplementation(Class<T> type) {
    * Returns an arbitrary instance for {@code type}, or {@code null} if no arbitrary instance can be
    * determined.
    */
-  @NullableDecl
+  @CheckForNull
   public static <T> T get(Class<T> type) {
     T defaultValue = DEFAULTS.getInstance(type);
     if (defaultValue != null) {
@@ -386,7 +385,7 @@ public static <T> T get(Class<T> type) {
     }
   }
 
-  @NullableDecl
+  @CheckForNull
   private static <T> T arbitraryConstantInstanceOrNull(Class<T> type) {
     Field[] fields = type.getDeclaredFields();
     Arrays.sort(fields, BY_FIELD_NAME);
@@ -430,6 +429,7 @@ public InMemoryPrintWriter() {
     }
 
     public static final class DeterministicRandom extends Random {
+      @Keep
       public DeterministicRandom() {
         super(0);
       }
diff --git a/android/guava-testlib/src/com/google/common/testing/ClassSanityTester.java b/android/guava-testlib/src/com/google/common/testing/ClassSanityTester.java
index 55f167eddd86..09317854571a 100644
--- a/android/guava-testlib/src/com/google/common/testing/ClassSanityTester.java
+++ b/android/guava-testlib/src/com/google/common/testing/ClassSanityTester.java
@@ -50,9 +50,9 @@
 import java.util.List;
 import java.util.Map.Entry;
 import java.util.Set;
+import javax.annotation.CheckForNull;
 import junit.framework.Assert;
 import junit.framework.AssertionFailedError;
-import org.checkerframework.checker.nullness.compatqual.NullableDecl;
 
 /**
  * Tester that runs automated sanity tests for any given class. A typical use case is to test static
@@ -334,7 +334,7 @@ void doTestEquals(Class<?> cls)
    * @return The instantiated instance, or {@code null} if the class has no non-private constructor
    *     or factory method to be constructed.
    */
-  @NullableDecl
+  @CheckForNull
   <T> T instantiate(Class<T> cls)
       throws ParameterNotInstantiableException, IllegalAccessException, InvocationTargetException,
           FactoryMethodReturnsNullException {
@@ -383,7 +383,7 @@ <T> T instantiate(Class<T> cls)
    *     class, preventing its methods from being accessible.
    * @throws InvocationTargetException if a static method threw exception.
    */
-  @NullableDecl
+  @CheckForNull
   private <T> T instantiate(Invokable<?, ? extends T> factory)
       throws ParameterNotInstantiableException, InvocationTargetException, IllegalAccessException {
     return invoke(factory, getDummyArguments(factory));
@@ -664,7 +664,7 @@ Object interfaceMethodCalled(Class<?> interfaceType, Method method) {
     return generator;
   }
 
-  @NullableDecl
+  @CheckForNull
   private static Object generateDummyArg(Parameter param, FreshValueGenerator generator)
       throws ParameterNotInstantiableException {
     if (isNullable(param)) {
@@ -761,7 +761,7 @@ private static <T> T createInstance(Invokable<?, ? extends T> factory, List<?> a
     return instance;
   }
 
-  @NullableDecl
+  @CheckForNull
   private static <T> T invoke(Invokable<?, ? extends T> factory, List<?> args)
       throws InvocationTargetException, IllegalAccessException {
     T returnValue = factory.invoke(null, args.toArray());
diff --git a/android/guava-testlib/src/com/google/common/testing/EqualsTester.java b/android/guava-testlib/src/com/google/common/testing/EqualsTester.java
index 2c8e08b87c57..9c93c9a492a1 100644
--- a/android/guava-testlib/src/com/google/common/testing/EqualsTester.java
+++ b/android/guava-testlib/src/com/google/common/testing/EqualsTester.java
@@ -20,7 +20,6 @@
 import static junit.framework.Assert.assertEquals;
 import static junit.framework.Assert.assertTrue;
 
-import com.google.common.annotations.Beta;
 import com.google.common.annotations.GwtCompatible;
 import com.google.common.base.Equivalence;
 import com.google.common.collect.ImmutableList;
@@ -74,7 +73,6 @@
  * @author Jige Yu
  * @since 10.0
  */
-@Beta
 @GwtCompatible
 public final class EqualsTester {
   private static final int REPETITIONS = 3;
@@ -122,7 +120,7 @@ private void testItems() {
       assertTrue(
           item + " must not be Object#equals to an arbitrary object of another class",
           !item.equals(NotAnInstance.EQUAL_TO_NOTHING));
-      assertEquals(item + " must be Object#equals to itself", item, item);
+      assertTrue(item + " must be Object#equals to itself", item.equals(item));
       assertEquals(
           "the Object#hashCode of " + item + " must be consistent",
           item.hashCode(),
diff --git a/android/guava-testlib/src/com/google/common/testing/EquivalenceTester.java b/android/guava-testlib/src/com/google/common/testing/EquivalenceTester.java
index ce1dc98c440e..8de2625d0ed6 100644
--- a/android/guava-testlib/src/com/google/common/testing/EquivalenceTester.java
+++ b/android/guava-testlib/src/com/google/common/testing/EquivalenceTester.java
@@ -20,7 +20,6 @@
 import static junit.framework.Assert.assertEquals;
 import static junit.framework.Assert.assertTrue;
 
-import com.google.common.annotations.Beta;
 import com.google.common.annotations.GwtCompatible;
 import com.google.common.base.Equivalence;
 import com.google.common.collect.ImmutableList;
@@ -49,7 +48,6 @@
  * @author Gregory Kick
  * @since 10.0
  */
-@Beta
 @GwtCompatible
 public final class EquivalenceTester<T> {
   private static final int REPETITIONS = 3;
@@ -60,12 +58,11 @@ public final class EquivalenceTester<T> {
 
   private EquivalenceTester(Equivalence<? super T> equivalence) {
     this.equivalence = checkNotNull(equivalence);
-    this.delegate =
-        new RelationshipTester<T>(equivalence, "equivalent", "hash", new ItemReporter());
+    this.delegate = new RelationshipTester<>(equivalence, "equivalent", "hash", new ItemReporter());
   }
 
   public static <T> EquivalenceTester<T> of(Equivalence<? super T> equivalence) {
-    return new EquivalenceTester<T>(equivalence);
+    return new EquivalenceTester<>(equivalence);
   }
 
   /**
diff --git a/android/guava-testlib/src/com/google/common/testing/FakeTicker.java b/android/guava-testlib/src/com/google/common/testing/FakeTicker.java
index 698db6a002d5..573635393e74 100644
--- a/android/guava-testlib/src/com/google/common/testing/FakeTicker.java
+++ b/android/guava-testlib/src/com/google/common/testing/FakeTicker.java
@@ -18,7 +18,6 @@
 
 import static com.google.common.base.Preconditions.checkArgument;
 
-import com.google.common.annotations.Beta;
 import com.google.common.annotations.GwtCompatible;
 import com.google.common.base.Ticker;
 import java.util.concurrent.TimeUnit;
@@ -35,7 +34,6 @@
  * @author Jige Yu
  * @since 10.0
  */
-@Beta
 @GwtCompatible
 public class FakeTicker extends Ticker {
 
diff --git a/android/guava-testlib/src/com/google/common/testing/ForwardingWrapperTester.java b/android/guava-testlib/src/com/google/common/testing/ForwardingWrapperTester.java
index 4ee461eb245f..605d3a055b28 100644
--- a/android/guava-testlib/src/com/google/common/testing/ForwardingWrapperTester.java
+++ b/android/guava-testlib/src/com/google/common/testing/ForwardingWrapperTester.java
@@ -22,7 +22,6 @@
 import static junit.framework.Assert.assertEquals;
 import static junit.framework.Assert.fail;
 
-import com.google.common.annotations.Beta;
 import com.google.common.annotations.GwtIncompatible;
 import com.google.common.base.Function;
 import com.google.common.base.Throwables;
@@ -53,7 +52,6 @@
  * @author Ben Yu
  * @since 14.0
  */
-@Beta
 @GwtIncompatible
 public final class ForwardingWrapperTester {
 
@@ -129,7 +127,7 @@ private static <T> void testSuccessfulForwarding(
 
   private static <T> void testExceptionPropagation(
       Class<T> interfaceType, Method method, Function<? super T, ? extends T> wrapperFunction) {
-    final RuntimeException exception = new RuntimeException();
+    RuntimeException exception = new RuntimeException();
     T proxy =
         Reflection.newProxy(
             interfaceType,
@@ -175,7 +173,7 @@ private static <T> void testToString(
 
   private static Object[] getParameterValues(Method method) {
     FreshValueGenerator paramValues = new FreshValueGenerator();
-    final List<Object> passedArgs = Lists.newArrayList();
+    List<Object> passedArgs = Lists.newArrayList();
     for (Class<?> paramType : method.getParameterTypes()) {
       passedArgs.add(paramValues.generateFresh(paramType));
     }
diff --git a/android/guava-testlib/src/com/google/common/testing/FreshValueGenerator.java b/android/guava-testlib/src/com/google/common/testing/FreshValueGenerator.java
index 21e25cb96c93..259f50c45214 100644
--- a/android/guava-testlib/src/com/google/common/testing/FreshValueGenerator.java
+++ b/android/guava-testlib/src/com/google/common/testing/FreshValueGenerator.java
@@ -118,7 +118,7 @@
 import java.util.concurrent.ConcurrentMap;
 import java.util.concurrent.atomic.AtomicInteger;
 import java.util.regex.Pattern;
-import org.checkerframework.checker.nullness.compatqual.NullableDecl;
+import javax.annotation.CheckForNull;
 
 /**
  * Generates fresh instances of types that are different from each other (if possible).
@@ -137,7 +137,7 @@ class FreshValueGenerator {
         builder.put(method.getReturnType(), method);
       }
     }
-    GENERATORS = builder.build();
+    GENERATORS = builder.buildOrThrow();
   }
 
   private static final ImmutableMap<Class<?>, Method> EMPTY_GENERATORS;
@@ -149,7 +149,7 @@ class FreshValueGenerator {
         builder.put(method.getReturnType(), method);
       }
     }
-    EMPTY_GENERATORS = builder.build();
+    EMPTY_GENERATORS = builder.buildOrThrow();
   }
 
   private final AtomicInteger freshness = new AtomicInteger(1);
@@ -175,7 +175,7 @@ final <T> void addSampleInstances(Class<T> type, Iterable<? extends T> instances
    *   <li>null if no value can be generated.
    * </ul>
    */
-  @NullableDecl
+  @CheckForNull
   final Object generateFresh(TypeToken<?> type) {
     Object generated = generate(type);
     if (generated != null) {
@@ -184,7 +184,7 @@ final Object generateFresh(TypeToken<?> type) {
     return generated;
   }
 
-  @NullableDecl
+  @CheckForNull
   final <T> T generateFresh(Class<T> type) {
     return Primitives.wrap(type).cast(generateFresh(TypeToken.of(type)));
   }
@@ -299,7 +299,7 @@ public int hashCode() {
     }
 
     @Override
-    public boolean equals(@NullableDecl Object obj) {
+    public boolean equals(@CheckForNull Object obj) {
       if (obj instanceof FreshInvocationHandler) {
         FreshInvocationHandler that = (FreshInvocationHandler) obj;
         return identity == that.identity;
@@ -354,7 +354,7 @@ private static String paramString(Class<?> type, int i) {
   private @interface Empty {}
 
   @Generates
-  private Class<?> generateClass() {
+  Class<?> generateClass() {
     return pickInstance(
         ImmutableList.of(
             int.class, long.class, void.class, Object.class, Object[].class, Iterable.class),
@@ -362,147 +362,147 @@ private Class<?> generateClass() {
   }
 
   @Generates
-  private Object generateObject() {
+  Object generateObject() {
     return generateString();
   }
 
   @Generates
-  private Number generateNumber() {
+  Number generateNumber() {
     return generateInt();
   }
 
   @Generates
-  private int generateInt() {
+  int generateInt() {
     return freshness.get();
   }
 
   @Generates
-  private Integer generateInteger() {
+  Integer generateInteger() {
     return new Integer(generateInt());
   }
 
   @Generates
-  private long generateLong() {
+  long generateLong() {
     return generateInt();
   }
 
   @Generates
-  private Long generateLongObject() {
+  Long generateLongObject() {
     return new Long(generateLong());
   }
 
   @Generates
-  private float generateFloat() {
+  float generateFloat() {
     return generateInt();
   }
 
   @Generates
-  private Float generateFloatObject() {
+  Float generateFloatObject() {
     return new Float(generateFloat());
   }
 
   @Generates
-  private double generateDouble() {
+  double generateDouble() {
     return generateInt();
   }
 
   @Generates
-  private Double generateDoubleObject() {
+  Double generateDoubleObject() {
     return new Double(generateDouble());
   }
 
   @Generates
-  private short generateShort() {
+  short generateShort() {
     return (short) generateInt();
   }
 
   @Generates
-  private Short generateShortObject() {
+  Short generateShortObject() {
     return new Short(generateShort());
   }
 
   @Generates
-  private byte generateByte() {
+  byte generateByte() {
     return (byte) generateInt();
   }
 
   @Generates
-  private Byte generateByteObject() {
+  Byte generateByteObject() {
     return new Byte(generateByte());
   }
 
   @Generates
-  private char generateChar() {
+  char generateChar() {
     return generateString().charAt(0);
   }
 
   @Generates
-  private Character generateCharacter() {
+  Character generateCharacter() {
     return new Character(generateChar());
   }
 
   @Generates
-  private boolean generateBoolean() {
+  boolean generateBoolean() {
     return generateInt() % 2 == 0;
   }
 
   @Generates
-  private Boolean generateBooleanObject() {
+  Boolean generateBooleanObject() {
     return new Boolean(generateBoolean());
   }
 
   @Generates
-  private UnsignedInteger generateUnsignedInteger() {
+  UnsignedInteger generateUnsignedInteger() {
     return UnsignedInteger.fromIntBits(generateInt());
   }
 
   @Generates
-  private UnsignedLong generateUnsignedLong() {
+  UnsignedLong generateUnsignedLong() {
     return UnsignedLong.fromLongBits(generateLong());
   }
 
   @Generates
-  private BigInteger generateBigInteger() {
+  BigInteger generateBigInteger() {
     return BigInteger.valueOf(generateInt());
   }
 
   @Generates
-  private BigDecimal generateBigDecimal() {
+  BigDecimal generateBigDecimal() {
     return BigDecimal.valueOf(generateInt());
   }
 
   @Generates
-  private CharSequence generateCharSequence() {
+  CharSequence generateCharSequence() {
     return generateString();
   }
 
   @Generates
-  private String generateString() {
+  String generateString() {
     return Integer.toString(generateInt());
   }
 
   @Generates
-  private Comparable<?> generateComparable() {
+  Comparable<?> generateComparable() {
     return generateString();
   }
 
   @Generates
-  private Pattern generatePattern() {
+  Pattern generatePattern() {
     return Pattern.compile(generateString());
   }
 
   @Generates
-  private Charset generateCharset() {
+  Charset generateCharset() {
     return pickInstance(Charset.availableCharsets().values(), Charsets.UTF_8);
   }
 
   @Generates
-  private Locale generateLocale() {
+  Locale generateLocale() {
     return pickInstance(Locale.getAvailableLocales(), Locale.US);
   }
 
   @Generates
-  private Currency generateCurrency() {
+  Currency generateCurrency() {
     try {
       Method method = Currency.class.getMethod("getAvailableCurrencies");
       @SuppressWarnings("unchecked") // getAvailableCurrencies() returns Set<Currency>.
@@ -538,27 +538,27 @@ private Currency preJava7FreshCurrency() {
 
   // common.base
   @Empty
-  private <T> com.google.common.base.Optional<T> generateGoogleOptional() {
+  <T> com.google.common.base.Optional<T> generateGoogleOptional() {
     return com.google.common.base.Optional.absent();
   }
 
   @Generates
-  private <T> com.google.common.base.Optional<T> generateGoogleOptional(T value) {
+  <T> com.google.common.base.Optional<T> generateGoogleOptional(T value) {
     return com.google.common.base.Optional.of(value);
   }
 
   @Generates
-  private Joiner generateJoiner() {
+  Joiner generateJoiner() {
     return Joiner.on(generateString());
   }
 
   @Generates
-  private Splitter generateSplitter() {
+  Splitter generateSplitter() {
     return Splitter.on(generateString());
   }
 
   @Generates
-  private <T> Equivalence<T> generateEquivalence() {
+  <T> Equivalence<T> generateEquivalence() {
     return new Equivalence<T>() {
       @Override
       protected boolean doEquivalent(T a, T b) {
@@ -580,7 +580,7 @@ public String toString() {
   }
 
   @Generates
-  private CharMatcher generateCharMatcher() {
+  CharMatcher generateCharMatcher() {
     return new CharMatcher() {
       @Override
       public boolean matches(char c) {
@@ -597,7 +597,7 @@ public String toString() {
   }
 
   @Generates
-  private Ticker generateTicker() {
+  Ticker generateTicker() {
     return new Ticker() {
       @Override
       public long read() {
@@ -615,12 +615,12 @@ public String toString() {
 
   // collect
   @Generates
-  private <T> Comparator<T> generateComparator() {
+  <T> Comparator<T> generateComparator() {
     return generateOrdering();
   }
 
   @Generates
-  private <T> Ordering<T> generateOrdering() {
+  <T> Ordering<T> generateOrdering() {
     return new Ordering<T>() {
       @Override
       public int compare(T left, T right) {
@@ -637,279 +637,283 @@ public String toString() {
   }
 
   @Empty
-  private static <C extends Comparable<?>> Range<C> generateRange() {
+  static <C extends Comparable<?>> Range<C> generateRange() {
     return Range.all();
   }
 
   @Generates
-  private static <C extends Comparable<?>> Range<C> generateRange(C freshElement) {
+  static <C extends Comparable<?>> Range<C> generateRange(C freshElement) {
     return Range.singleton(freshElement);
   }
 
   @Generates
-  private static <E> Iterable<E> generateIterable(E freshElement) {
+  static <E> Iterable<E> generateIterable(@CheckForNull E freshElement) {
     return generateList(freshElement);
   }
 
   @Generates
-  private static <E> Collection<E> generateCollection(E freshElement) {
+  static <E> Collection<E> generateCollection(@CheckForNull E freshElement) {
     return generateList(freshElement);
   }
 
   @Generates
-  private static <E> List<E> generateList(E freshElement) {
+  static <E> List<E> generateList(@CheckForNull E freshElement) {
     return generateArrayList(freshElement);
   }
 
   @Generates
-  private static <E> ArrayList<E> generateArrayList(E freshElement) {
+  static <E> ArrayList<E> generateArrayList(@CheckForNull E freshElement) {
     ArrayList<E> list = Lists.newArrayList();
     list.add(freshElement);
     return list;
   }
 
   @Generates
-  private static <E> LinkedList<E> generateLinkedList(E freshElement) {
+  static <E> LinkedList<E> generateLinkedList(@CheckForNull E freshElement) {
     LinkedList<E> list = Lists.newLinkedList();
     list.add(freshElement);
     return list;
   }
 
   @Generates
-  private static <E> ImmutableList<E> generateImmutableList(E freshElement) {
+  static <E> ImmutableList<E> generateImmutableList(E freshElement) {
     return ImmutableList.of(freshElement);
   }
 
   @Generates
-  private static <E> ImmutableCollection<E> generateImmutableCollection(E freshElement) {
+  static <E> ImmutableCollection<E> generateImmutableCollection(E freshElement) {
     return generateImmutableList(freshElement);
   }
 
   @Generates
-  private static <E> Set<E> generateSet(E freshElement) {
+  static <E> Set<E> generateSet(@CheckForNull E freshElement) {
     return generateHashSet(freshElement);
   }
 
   @Generates
-  private static <E> HashSet<E> generateHashSet(E freshElement) {
+  static <E> HashSet<E> generateHashSet(@CheckForNull E freshElement) {
     return generateLinkedHashSet(freshElement);
   }
 
   @Generates
-  private static <E> LinkedHashSet<E> generateLinkedHashSet(E freshElement) {
+  static <E> LinkedHashSet<E> generateLinkedHashSet(@CheckForNull E freshElement) {
     LinkedHashSet<E> set = Sets.newLinkedHashSet();
     set.add(freshElement);
     return set;
   }
 
   @Generates
-  private static <E> ImmutableSet<E> generateImmutableSet(E freshElement) {
+  static <E> ImmutableSet<E> generateImmutableSet(E freshElement) {
     return ImmutableSet.of(freshElement);
   }
 
   @Generates
-  private static <E extends Comparable<? super E>> SortedSet<E> generateSortedSet(E freshElement) {
+  static <E extends Comparable<? super E>> SortedSet<E> generateSortedSet(E freshElement) {
     return generateNavigableSet(freshElement);
   }
 
   @Generates
-  private static <E extends Comparable<? super E>> NavigableSet<E> generateNavigableSet(
-      E freshElement) {
+  static <E extends Comparable<? super E>> NavigableSet<E> generateNavigableSet(E freshElement) {
     return generateTreeSet(freshElement);
   }
 
   @Generates
-  private static <E extends Comparable<? super E>> TreeSet<E> generateTreeSet(E freshElement) {
+  static <E extends Comparable<? super E>> TreeSet<E> generateTreeSet(E freshElement) {
     TreeSet<E> set = Sets.newTreeSet();
     set.add(freshElement);
     return set;
   }
 
   @Generates
-  private static <E extends Comparable<? super E>> ImmutableSortedSet<E> generateImmutableSortedSet(
+  static <E extends Comparable<? super E>> ImmutableSortedSet<E> generateImmutableSortedSet(
       E freshElement) {
     return ImmutableSortedSet.of(freshElement);
   }
 
   @Generates
-  private static <E> Multiset<E> generateMultiset(E freshElement) {
+  static <E> Multiset<E> generateMultiset(@CheckForNull E freshElement) {
     return generateHashMultiset(freshElement);
   }
 
   @Generates
-  private static <E> HashMultiset<E> generateHashMultiset(E freshElement) {
+  static <E> HashMultiset<E> generateHashMultiset(@CheckForNull E freshElement) {
     HashMultiset<E> multiset = HashMultiset.create();
     multiset.add(freshElement);
     return multiset;
   }
 
   @Generates
-  private static <E> LinkedHashMultiset<E> generateLinkedHashMultiset(E freshElement) {
+  static <E> LinkedHashMultiset<E> generateLinkedHashMultiset(@CheckForNull E freshElement) {
     LinkedHashMultiset<E> multiset = LinkedHashMultiset.create();
     multiset.add(freshElement);
     return multiset;
   }
 
   @Generates
-  private static <E> ImmutableMultiset<E> generateImmutableMultiset(E freshElement) {
+  static <E> ImmutableMultiset<E> generateImmutableMultiset(E freshElement) {
     return ImmutableMultiset.of(freshElement);
   }
 
   @Generates
-  private static <E extends Comparable<E>> SortedMultiset<E> generateSortedMultiset(
-      E freshElement) {
+  static <E extends Comparable<E>> SortedMultiset<E> generateSortedMultiset(E freshElement) {
     return generateTreeMultiset(freshElement);
   }
 
   @Generates
-  private static <E extends Comparable<E>> TreeMultiset<E> generateTreeMultiset(E freshElement) {
+  static <E extends Comparable<E>> TreeMultiset<E> generateTreeMultiset(E freshElement) {
     TreeMultiset<E> multiset = TreeMultiset.create();
     multiset.add(freshElement);
     return multiset;
   }
 
   @Generates
-  private static <E extends Comparable<E>>
-      ImmutableSortedMultiset<E> generateImmutableSortedMultiset(E freshElement) {
+  static <E extends Comparable<E>> ImmutableSortedMultiset<E> generateImmutableSortedMultiset(
+      E freshElement) {
     return ImmutableSortedMultiset.of(freshElement);
   }
 
   @Generates
-  private static <K, V> Map<K, V> generateMap(K key, V value) {
+  static <K, V> Map<K, V> generateMap(@CheckForNull K key, @CheckForNull V value) {
     return generateHashdMap(key, value);
   }
 
   @Generates
-  private static <K, V> HashMap<K, V> generateHashdMap(K key, V value) {
+  static <K, V> HashMap<K, V> generateHashdMap(@CheckForNull K key, @CheckForNull V value) {
     return generateLinkedHashMap(key, value);
   }
 
   @Generates
-  private static <K, V> LinkedHashMap<K, V> generateLinkedHashMap(K key, V value) {
+  static <K, V> LinkedHashMap<K, V> generateLinkedHashMap(
+      @CheckForNull K key, @CheckForNull V value) {
     LinkedHashMap<K, V> map = Maps.newLinkedHashMap();
     map.put(key, value);
     return map;
   }
 
   @Generates
-  private static <K, V> ImmutableMap<K, V> generateImmutableMap(K key, V value) {
+  static <K, V> ImmutableMap<K, V> generateImmutableMap(K key, V value) {
     return ImmutableMap.of(key, value);
   }
 
   @Empty
-  private static <K, V> ConcurrentMap<K, V> generateConcurrentMap() {
+  static <K, V> ConcurrentMap<K, V> generateConcurrentMap() {
     return Maps.newConcurrentMap();
   }
 
   @Generates
-  private static <K, V> ConcurrentMap<K, V> generateConcurrentMap(K key, V value) {
+  static <K, V> ConcurrentMap<K, V> generateConcurrentMap(K key, V value) {
     ConcurrentMap<K, V> map = Maps.newConcurrentMap();
     map.put(key, value);
     return map;
   }
 
   @Generates
-  private static <K extends Comparable<? super K>, V> SortedMap<K, V> generateSortedMap(
-      K key, V value) {
+  static <K extends Comparable<? super K>, V> SortedMap<K, V> generateSortedMap(
+      K key, @CheckForNull V value) {
     return generateNavigableMap(key, value);
   }
 
   @Generates
-  private static <K extends Comparable<? super K>, V> NavigableMap<K, V> generateNavigableMap(
-      K key, V value) {
+  static <K extends Comparable<? super K>, V> NavigableMap<K, V> generateNavigableMap(
+      K key, @CheckForNull V value) {
     return generateTreeMap(key, value);
   }
 
   @Generates
-  private static <K extends Comparable<? super K>, V> TreeMap<K, V> generateTreeMap(
-      K key, V value) {
+  static <K extends Comparable<? super K>, V> TreeMap<K, V> generateTreeMap(
+      K key, @CheckForNull V value) {
     TreeMap<K, V> map = Maps.newTreeMap();
     map.put(key, value);
     return map;
   }
 
   @Generates
-  private static <K extends Comparable<? super K>, V>
-      ImmutableSortedMap<K, V> generateImmutableSortedMap(K key, V value) {
+  static <K extends Comparable<? super K>, V> ImmutableSortedMap<K, V> generateImmutableSortedMap(
+      K key, V value) {
     return ImmutableSortedMap.of(key, value);
   }
 
   @Generates
-  private static <K, V> Multimap<K, V> generateMultimap(K key, V value) {
+  static <K, V> Multimap<K, V> generateMultimap(@CheckForNull K key, @CheckForNull V value) {
     return generateListMultimap(key, value);
   }
 
   @Generates
-  private static <K, V> ImmutableMultimap<K, V> generateImmutableMultimap(K key, V value) {
+  static <K, V> ImmutableMultimap<K, V> generateImmutableMultimap(K key, V value) {
     return ImmutableMultimap.of(key, value);
   }
 
   @Generates
-  private static <K, V> ListMultimap<K, V> generateListMultimap(K key, V value) {
+  static <K, V> ListMultimap<K, V> generateListMultimap(
+      @CheckForNull K key, @CheckForNull V value) {
     return generateArrayListMultimap(key, value);
   }
 
   @Generates
-  private static <K, V> ArrayListMultimap<K, V> generateArrayListMultimap(K key, V value) {
+  static <K, V> ArrayListMultimap<K, V> generateArrayListMultimap(
+      @CheckForNull K key, @CheckForNull V value) {
     ArrayListMultimap<K, V> multimap = ArrayListMultimap.create();
     multimap.put(key, value);
     return multimap;
   }
 
   @Generates
-  private static <K, V> ImmutableListMultimap<K, V> generateImmutableListMultimap(K key, V value) {
+  static <K, V> ImmutableListMultimap<K, V> generateImmutableListMultimap(K key, V value) {
     return ImmutableListMultimap.of(key, value);
   }
 
   @Generates
-  private static <K, V> SetMultimap<K, V> generateSetMultimap(K key, V value) {
+  static <K, V> SetMultimap<K, V> generateSetMultimap(@CheckForNull K key, @CheckForNull V value) {
     return generateLinkedHashMultimap(key, value);
   }
 
   @Generates
-  private static <K, V> HashMultimap<K, V> generateHashMultimap(K key, V value) {
+  static <K, V> HashMultimap<K, V> generateHashMultimap(
+      @CheckForNull K key, @CheckForNull V value) {
     HashMultimap<K, V> multimap = HashMultimap.create();
     multimap.put(key, value);
     return multimap;
   }
 
   @Generates
-  private static <K, V> LinkedHashMultimap<K, V> generateLinkedHashMultimap(K key, V value) {
+  static <K, V> LinkedHashMultimap<K, V> generateLinkedHashMultimap(
+      @CheckForNull K key, @CheckForNull V value) {
     LinkedHashMultimap<K, V> multimap = LinkedHashMultimap.create();
     multimap.put(key, value);
     return multimap;
   }
 
   @Generates
-  private static <K, V> ImmutableSetMultimap<K, V> generateImmutableSetMultimap(K key, V value) {
+  static <K, V> ImmutableSetMultimap<K, V> generateImmutableSetMultimap(K key, V value) {
     return ImmutableSetMultimap.of(key, value);
   }
 
   @Generates
-  private static <K, V> BiMap<K, V> generateBimap(K key, V value) {
+  static <K, V> BiMap<K, V> generateBimap(@CheckForNull K key, @CheckForNull V value) {
     return generateHashBiMap(key, value);
   }
 
   @Generates
-  private static <K, V> HashBiMap<K, V> generateHashBiMap(K key, V value) {
+  static <K, V> HashBiMap<K, V> generateHashBiMap(@CheckForNull K key, @CheckForNull V value) {
     HashBiMap<K, V> bimap = HashBiMap.create();
     bimap.put(key, value);
     return bimap;
   }
 
   @Generates
-  private static <K, V> ImmutableBiMap<K, V> generateImmutableBimap(K key, V value) {
+  static <K, V> ImmutableBiMap<K, V> generateImmutableBimap(K key, V value) {
     return ImmutableBiMap.of(key, value);
   }
 
   @Generates
-  private static <R, C, V> Table<R, C, V> generateTable(R row, C column, V value) {
+  static <R, C, V> Table<R, C, V> generateTable(
+      @CheckForNull R row, @CheckForNull C column, @CheckForNull V value) {
     return generateHashBasedTable(row, column, value);
   }
 
   @Generates
-  private static <R, C, V> HashBasedTable<R, C, V> generateHashBasedTable(
-      R row, C column, V value) {
+  static <R, C, V> HashBasedTable<R, C, V> generateHashBasedTable(
+      @CheckForNull R row, @CheckForNull C column, @CheckForNull V value) {
     HashBasedTable<R, C, V> table = HashBasedTable.create();
     table.put(row, column, value);
     return table;
@@ -917,14 +921,14 @@ private static <R, C, V> HashBasedTable<R, C, V> generateHashBasedTable(
 
   @SuppressWarnings("rawtypes") // TreeBasedTable.create() is defined as such
   @Generates
-  private static <R extends Comparable, C extends Comparable, V>
+  static <R extends Comparable, C extends Comparable, V>
       RowSortedTable<R, C, V> generateRowSortedTable(R row, C column, V value) {
     return generateTreeBasedTable(row, column, value);
   }
 
   @SuppressWarnings("rawtypes") // TreeBasedTable.create() is defined as such
   @Generates
-  private static <R extends Comparable, C extends Comparable, V>
+  static <R extends Comparable, C extends Comparable, V>
       TreeBasedTable<R, C, V> generateTreeBasedTable(R row, C column, V value) {
     TreeBasedTable<R, C, V> table = TreeBasedTable.create();
     table.put(row, column, value);
@@ -932,85 +936,84 @@ TreeBasedTable<R, C, V> generateTreeBasedTable(R row, C column, V value) {
   }
 
   @Generates
-  private static <R, C, V> ImmutableTable<R, C, V> generateImmutableTable(
-      R row, C column, V value) {
+  static <R, C, V> ImmutableTable<R, C, V> generateImmutableTable(R row, C column, V value) {
     return ImmutableTable.of(row, column, value);
   }
 
   // common.reflect
   @Generates
-  private TypeToken<?> generateTypeToken() {
+  TypeToken<?> generateTypeToken() {
     return TypeToken.of(generateClass());
   }
 
   // io types
   @Generates
-  private File generateFile() {
+  File generateFile() {
     return new File(generateString());
   }
 
   @Generates
-  private static ByteArrayInputStream generateByteArrayInputStream() {
+  static ByteArrayInputStream generateByteArrayInputStream() {
     return new ByteArrayInputStream(new byte[0]);
   }
 
   @Generates
-  private static InputStream generateInputStream() {
+  static InputStream generateInputStream() {
     return generateByteArrayInputStream();
   }
 
   @Generates
-  private StringReader generateStringReader() {
+  StringReader generateStringReader() {
     return new StringReader(generateString());
   }
 
   @Generates
-  private Reader generateReader() {
+  Reader generateReader() {
     return generateStringReader();
   }
 
   @Generates
-  private Readable generateReadable() {
+  Readable generateReadable() {
     return generateReader();
   }
 
   @Generates
-  private Buffer generateBuffer() {
+  Buffer generateBuffer() {
     return generateCharBuffer();
   }
 
   @Generates
-  private CharBuffer generateCharBuffer() {
+  CharBuffer generateCharBuffer() {
     return CharBuffer.allocate(generateInt());
   }
 
   @Generates
-  private ByteBuffer generateByteBuffer() {
+  ByteBuffer generateByteBuffer() {
     return ByteBuffer.allocate(generateInt());
   }
 
   @Generates
-  private ShortBuffer generateShortBuffer() {
+  ShortBuffer generateShortBuffer() {
     return ShortBuffer.allocate(generateInt());
   }
 
   @Generates
-  private IntBuffer generateIntBuffer() {
+  IntBuffer generateIntBuffer() {
     return IntBuffer.allocate(generateInt());
   }
 
   @Generates
-  private LongBuffer generateLongBuffer() {
+  LongBuffer generateLongBuffer() {
     return LongBuffer.allocate(generateInt());
   }
 
   @Generates
-  private FloatBuffer generateFloatBuffer() {
+  FloatBuffer generateFloatBuffer() {
     return FloatBuffer.allocate(generateInt());
   }
 
   @Generates
-  private DoubleBuffer generateDoubleBuffer() {
+  DoubleBuffer generateDoubleBuffer() {
     return DoubleBuffer.allocate(generateInt());
   }
 }
diff --git a/android/guava-testlib/src/com/google/common/testing/GcFinalization.java b/android/guava-testlib/src/com/google/common/testing/GcFinalization.java
index 015afea54809..da6aa2211b49 100644
--- a/android/guava-testlib/src/com/google/common/testing/GcFinalization.java
+++ b/android/guava-testlib/src/com/google/common/testing/GcFinalization.java
@@ -18,7 +18,6 @@
 
 import static java.util.concurrent.TimeUnit.SECONDS;
 
-import com.google.common.annotations.Beta;
 import com.google.common.annotations.GwtIncompatible;
 import com.google.errorprone.annotations.DoNotMock;
 import com.google.j2objc.annotations.J2ObjCIncompatible;
@@ -103,7 +102,6 @@
  * @author Martin Buchholz
  * @since 11.0
  */
-@Beta
 @GwtIncompatible
 @J2ObjCIncompatible // gc
 public final class GcFinalization {
@@ -138,8 +136,8 @@ public static void awaitDone(Future<?> future) {
     if (future.isDone()) {
       return;
     }
-    final long timeoutSeconds = timeoutSeconds();
-    final long deadline = System.nanoTime() + SECONDS.toNanos(timeoutSeconds);
+    long timeoutSeconds = timeoutSeconds();
+    long deadline = System.nanoTime() + SECONDS.toNanos(timeoutSeconds);
     do {
       System.runFinalization();
       if (future.isDone()) {
@@ -170,8 +168,8 @@ public static void awaitDone(FinalizationPredicate predicate) {
     if (predicate.isDone()) {
       return;
     }
-    final long timeoutSeconds = timeoutSeconds();
-    final long deadline = System.nanoTime() + SECONDS.toNanos(timeoutSeconds);
+    long timeoutSeconds = timeoutSeconds();
+    long deadline = System.nanoTime() + SECONDS.toNanos(timeoutSeconds);
     do {
       System.runFinalization();
       if (predicate.isDone()) {
@@ -198,8 +196,8 @@ public static void await(CountDownLatch latch) {
     if (latch.getCount() == 0) {
       return;
     }
-    final long timeoutSeconds = timeoutSeconds();
-    final long deadline = System.nanoTime() + SECONDS.toNanos(timeoutSeconds);
+    long timeoutSeconds = timeoutSeconds();
+    long deadline = System.nanoTime() + SECONDS.toNanos(timeoutSeconds);
     do {
       System.runFinalization();
       if (latch.getCount() == 0) {
@@ -222,13 +220,14 @@ public static void await(CountDownLatch latch) {
    * Creates a garbage object that counts down the latch in its finalizer. Sequestered into a
    * separate method to make it somewhat more likely to be unreachable.
    */
-  private static void createUnreachableLatchFinalizer(final CountDownLatch latch) {
-    new Object() {
-      @Override
-      protected void finalize() {
-        latch.countDown();
-      }
-    };
+  private static void createUnreachableLatchFinalizer(CountDownLatch latch) {
+    Object unused =
+        new Object() {
+          @Override
+          protected void finalize() {
+            latch.countDown();
+          }
+        };
   }
 
   /**
@@ -263,7 +262,7 @@ public interface FinalizationPredicate {
    *
    * @throws RuntimeException if timed out or interrupted while waiting
    */
-  public static void awaitClear(final WeakReference<?> ref) {
+  public static void awaitClear(WeakReference<?> ref) {
     awaitDone(
         new FinalizationPredicate() {
           @Override
@@ -296,9 +295,9 @@ public boolean isDone() {
    * @since 12.0
    */
   public static void awaitFullGc() {
-    final CountDownLatch finalizerRan = new CountDownLatch(1);
+    CountDownLatch finalizerRan = new CountDownLatch(1);
     WeakReference<Object> ref =
-        new WeakReference<Object>(
+        new WeakReference<>(
             new Object() {
               @Override
               protected void finalize() {
diff --git a/android/guava-testlib/src/com/google/common/testing/NullPointerTester.java b/android/guava-testlib/src/com/google/common/testing/NullPointerTester.java
index a32a53b7b050..4c24c65e17a4 100644
--- a/android/guava-testlib/src/com/google/common/testing/NullPointerTester.java
+++ b/android/guava-testlib/src/com/google/common/testing/NullPointerTester.java
@@ -19,7 +19,6 @@
 import static com.google.common.base.Preconditions.checkArgument;
 import static com.google.common.base.Preconditions.checkNotNull;
 
-import com.google.common.annotations.Beta;
 import com.google.common.annotations.GwtIncompatible;
 import com.google.common.base.Converter;
 import com.google.common.base.Objects;
@@ -45,14 +44,14 @@
 import java.util.Arrays;
 import java.util.List;
 import java.util.concurrent.ConcurrentMap;
+import javax.annotation.CheckForNull;
 import junit.framework.Assert;
 import junit.framework.AssertionFailedError;
-import org.checkerframework.checker.nullness.compatqual.NullableDecl;
 
 /**
  * A test utility that verifies that your methods and constructors throw {@link
  * NullPointerException} or {@link UnsupportedOperationException} whenever null is passed to a
- * parameter that isn't annotated with an annotation with the simple name {@code Nullable}, {@lcode
+ * parameter that isn't annotated with an annotation with the simple name {@code Nullable}, {@code
  * CheckForNull}, {@link NullableType}, or {@link NullableDecl}.
  *
  * <p>The tested methods and constructors are invoked -- each time with one parameter being null and
@@ -66,7 +65,6 @@
  * @author Kevin Bourrillion
  * @since 10.0
  */
-@Beta
 @GwtIncompatible
 public final class NullPointerTester {
 
@@ -176,7 +174,7 @@ public void testAllPublicInstanceMethods(Object instance) {
    *
    * @param instance the instance to invoke {@code method} on, or null if {@code method} is static
    */
-  public void testMethod(@NullableDecl Object instance, Method method) {
+  public void testMethod(@CheckForNull Object instance, Method method) {
     Class<?>[] types = method.getParameterTypes();
     for (int nullIndex = 0; nullIndex < types.length; nullIndex++) {
       testMethodParameter(instance, method, nullIndex);
@@ -208,7 +206,7 @@ public void testConstructor(Constructor<?> ctor) {
    * @param instance the instance to invoke {@code method} on, or null if {@code method} is static
    */
   public void testMethodParameter(
-      @NullableDecl final Object instance, final Method method, int paramIndex) {
+      @CheckForNull final Object instance, final Method method, int paramIndex) {
     method.setAccessible(true);
     testParameter(instance, invokable(instance, method), paramIndex, method.getDeclaringClass());
   }
@@ -461,7 +459,7 @@ <R> R dummyReturnValue(TypeToken<R> returnType) {
     }.newProxy(type);
   }
 
-  private static Invokable<?, ?> invokable(@NullableDecl Object instance, Method method) {
+  private static Invokable<?, ?> invokable(@CheckForNull Object instance, Method method) {
     if (instance == null) {
       return Invokable.from(method);
     } else {
@@ -474,7 +472,8 @@ static boolean isPrimitiveOrNullable(Parameter param) {
   }
 
   private static final ImmutableSet<String> NULLABLE_ANNOTATION_SIMPLE_NAMES =
-      ImmutableSet.of("CheckForNull", "Nullable", "NullableDecl", "NullableType");
+      ImmutableSet.of(
+          "CheckForNull", "Nullable", "NullableDecl", "NullableType", "ParametricNullness");
 
   static boolean isNullable(AnnotatedElement e) {
     for (Annotation annotation : e.getAnnotations()) {
@@ -490,7 +489,7 @@ private boolean isIgnored(Member member) {
   }
 
   /**
-   * Returns true if the the given member is a method that overrides {@link Object#equals(Object)}.
+   * Returns true if the given member is a method that overrides {@link Object#equals(Object)}.
    *
    * <p>The documentation for {@link Object#equals} says it should accept null, so don't require an
    * explicit {@code @NullableDecl} annotation (see <a
diff --git a/android/guava-testlib/src/com/google/common/testing/RelationshipTester.java b/android/guava-testlib/src/com/google/common/testing/RelationshipTester.java
index 5adf01091a85..d5b9b6a18693 100644
--- a/android/guava-testlib/src/com/google/common/testing/RelationshipTester.java
+++ b/android/guava-testlib/src/com/google/common/testing/RelationshipTester.java
@@ -147,7 +147,7 @@ private void assertWithTemplate(String template, Item<T> item, Item<T> other, bo
   }
 
   private Item<T> getItem(int groupNumber, int itemNumber) {
-    return new Item<T>(groups.get(groupNumber).get(itemNumber), groupNumber, itemNumber);
+    return new Item<>(groups.get(groupNumber).get(itemNumber), groupNumber, itemNumber);
   }
 
   static final class Item<T> {
diff --git a/android/guava-testlib/src/com/google/common/testing/SerializableTester.java b/android/guava-testlib/src/com/google/common/testing/SerializableTester.java
index 62980764d65f..c4e6d236ee7e 100644
--- a/android/guava-testlib/src/com/google/common/testing/SerializableTester.java
+++ b/android/guava-testlib/src/com/google/common/testing/SerializableTester.java
@@ -16,7 +16,6 @@
 
 package com.google.common.testing;
 
-import com.google.common.annotations.Beta;
 import com.google.common.annotations.GwtCompatible;
 import junit.framework.Assert;
 import junit.framework.AssertionFailedError;
@@ -32,7 +31,6 @@
  * @author Mike Bostock
  * @since 10.0
  */
-@Beta
 @GwtCompatible // but no-op!
 public final class SerializableTester {
   private SerializableTester() {}
@@ -52,7 +50,6 @@ private SerializableTester() {}
    * @throws RuntimeException if the specified object was not successfully serialized or
    *     deserialized
    */
-  @SuppressWarnings("unchecked")
   public static <T> T reserialize(T object) {
     return Platform.reserialize(object);
   }
diff --git a/android/guava-testlib/src/com/google/common/testing/TestLogHandler.java b/android/guava-testlib/src/com/google/common/testing/TestLogHandler.java
index c03093be52f3..263f8908ac36 100644
--- a/android/guava-testlib/src/com/google/common/testing/TestLogHandler.java
+++ b/android/guava-testlib/src/com/google/common/testing/TestLogHandler.java
@@ -16,14 +16,13 @@
 
 package com.google.common.testing;
 
-import com.google.common.annotations.Beta;
 import com.google.common.annotations.GwtCompatible;
 import java.util.ArrayList;
 import java.util.Collections;
 import java.util.List;
 import java.util.logging.Handler;
 import java.util.logging.LogRecord;
-import org.checkerframework.checker.nullness.compatqual.NullableDecl;
+import javax.annotation.CheckForNull;
 
 /**
  * Tests may use this to intercept messages that are logged by the code under test. Example:
@@ -52,7 +51,6 @@
  * @author Kevin Bourrillion
  * @since 10.0
  */
-@Beta
 @GwtCompatible
 public class TestLogHandler extends Handler {
   /** We will keep a private list of all logged records */
@@ -60,7 +58,7 @@ public class TestLogHandler extends Handler {
 
   /** Adds the most recently logged record to our list. */
   @Override
-  public synchronized void publish(@NullableDecl LogRecord record) {
+  public synchronized void publish(@CheckForNull LogRecord record) {
     list.add(record);
   }
 
diff --git a/android/guava-testlib/src/com/google/common/util/concurrent/testing/AbstractListenableFutureTest.java b/android/guava-testlib/src/com/google/common/util/concurrent/testing/AbstractListenableFutureTest.java
index 2ba751537396..b5bec2c094bd 100644
--- a/android/guava-testlib/src/com/google/common/util/concurrent/testing/AbstractListenableFutureTest.java
+++ b/android/guava-testlib/src/com/google/common/util/concurrent/testing/AbstractListenableFutureTest.java
@@ -16,6 +16,9 @@
 
 package com.google.common.util.concurrent.testing;
 
+import static java.util.concurrent.TimeUnit.MILLISECONDS;
+import static java.util.concurrent.TimeUnit.SECONDS;
+
 import com.google.common.annotations.Beta;
 import com.google.common.annotations.GwtIncompatible;
 import com.google.common.util.concurrent.ListenableFuture;
@@ -68,21 +71,18 @@ public void testGetBlocksUntilValueAvailable() throws Throwable {
     assertFalse(future.isDone());
     assertFalse(future.isCancelled());
 
-    final CountDownLatch successLatch = new CountDownLatch(1);
-    final Throwable[] badness = new Throwable[1];
+    CountDownLatch successLatch = new CountDownLatch(1);
+    Throwable[] badness = new Throwable[1];
 
     // Wait on the future in a separate thread.
     new Thread(
-            new Runnable() {
-              @Override
-              public void run() {
-                try {
-                  assertSame(Boolean.TRUE, future.get());
-                  successLatch.countDown();
-                } catch (Throwable t) {
-                  t.printStackTrace();
-                  badness[0] = t;
-                }
+            () -> {
+              try {
+                assertSame(Boolean.TRUE, future.get());
+                successLatch.countDown();
+              } catch (Throwable t) {
+                t.printStackTrace();
+                badness[0] = t;
               }
             })
         .start();
@@ -90,7 +90,7 @@ public void run() {
     // Release the future value.
     latch.countDown();
 
-    assertTrue(successLatch.await(10, TimeUnit.SECONDS));
+    assertTrue(successLatch.await(10, SECONDS));
 
     if (badness[0] != null) {
       throw badness[0];
@@ -105,7 +105,7 @@ public void testTimeoutOnGetWorksCorrectly() throws InterruptedException, Execut
 
     // The task thread waits for the latch, so we expect a timeout here.
     try {
-      future.get(20, TimeUnit.MILLISECONDS);
+      future.get(20, MILLISECONDS);
       fail("Should have timed out trying to get the value.");
     } catch (TimeoutException expected) {
     } finally {
@@ -123,20 +123,17 @@ public void testCanceledFutureThrowsCancellation() throws Exception {
     assertFalse(future.isDone());
     assertFalse(future.isCancelled());
 
-    final CountDownLatch successLatch = new CountDownLatch(1);
+    CountDownLatch successLatch = new CountDownLatch(1);
 
     // Run cancellation in a separate thread as an extra thread-safety test.
     new Thread(
-            new Runnable() {
-              @Override
-              public void run() {
-                try {
-                  future.get();
-                } catch (CancellationException expected) {
-                  successLatch.countDown();
-                } catch (Exception ignored) {
-                  // All other errors are ignored, we expect a cancellation.
-                }
+            () -> {
+              try {
+                future.get();
+              } catch (CancellationException expected) {
+                successLatch.countDown();
+              } catch (Exception ignored) {
+                // All other errors are ignored, we expect a cancellation.
               }
             })
         .start();
@@ -149,37 +146,27 @@ public void run() {
     assertTrue(future.isDone());
     assertTrue(future.isCancelled());
 
-    assertTrue(successLatch.await(200, TimeUnit.MILLISECONDS));
+    assertTrue(successLatch.await(200, MILLISECONDS));
 
     latch.countDown();
   }
 
   public void testListenersNotifiedOnError() throws Exception {
-    final CountDownLatch successLatch = new CountDownLatch(1);
-    final CountDownLatch listenerLatch = new CountDownLatch(1);
+    CountDownLatch successLatch = new CountDownLatch(1);
+    CountDownLatch listenerLatch = new CountDownLatch(1);
 
     ExecutorService exec = Executors.newCachedThreadPool();
 
-    future.addListener(
-        new Runnable() {
-          @Override
-          public void run() {
-            listenerLatch.countDown();
-          }
-        },
-        exec);
+    future.addListener(listenerLatch::countDown, exec);
 
     new Thread(
-            new Runnable() {
-              @Override
-              public void run() {
-                try {
-                  future.get();
-                } catch (CancellationException expected) {
-                  successLatch.countDown();
-                } catch (Exception ignored) {
-                  // No success latch count down.
-                }
+            () -> {
+              try {
+                future.get();
+              } catch (CancellationException expected) {
+                successLatch.countDown();
+              } catch (Exception ignored) {
+                // No success latch count down.
               }
             })
         .start();
@@ -189,13 +176,13 @@ public void run() {
     assertTrue(future.isCancelled());
     assertTrue(future.isDone());
 
-    assertTrue(successLatch.await(200, TimeUnit.MILLISECONDS));
-    assertTrue(listenerLatch.await(200, TimeUnit.MILLISECONDS));
+    assertTrue(successLatch.await(200, MILLISECONDS));
+    assertTrue(listenerLatch.await(200, MILLISECONDS));
 
     latch.countDown();
 
     exec.shutdown();
-    exec.awaitTermination(100, TimeUnit.MILLISECONDS);
+    exec.awaitTermination(100, MILLISECONDS);
   }
 
   /**
@@ -209,7 +196,7 @@ public void testAllListenersCompleteSuccessfully()
     ExecutorService exec = Executors.newCachedThreadPool();
 
     int listenerCount = 20;
-    final CountDownLatch listenerLatch = new CountDownLatch(listenerCount);
+    CountDownLatch listenerLatch = new CountDownLatch(listenerCount);
 
     // Test that listeners added both before and after the value is available
     // get called correctly.
@@ -217,31 +204,17 @@ public void testAllListenersCompleteSuccessfully()
 
       // Right in the middle start up a thread to close the latch.
       if (i == 10) {
-        new Thread(
-                new Runnable() {
-                  @Override
-                  public void run() {
-                    latch.countDown();
-                  }
-                })
-            .start();
+        new Thread(() -> latch.countDown()).start();
       }
 
-      future.addListener(
-          new Runnable() {
-            @Override
-            public void run() {
-              listenerLatch.countDown();
-            }
-          },
-          exec);
+      future.addListener(listenerLatch::countDown, exec);
     }
 
     assertSame(Boolean.TRUE, future.get());
     // Wait for the listener latch to complete.
-    listenerLatch.await(500, TimeUnit.MILLISECONDS);
+    listenerLatch.await(500, MILLISECONDS);
 
     exec.shutdown();
-    exec.awaitTermination(500, TimeUnit.MILLISECONDS);
+    exec.awaitTermination(500, MILLISECONDS);
   }
 }
diff --git a/android/guava-testlib/src/com/google/common/util/concurrent/testing/MockFutureListener.java b/android/guava-testlib/src/com/google/common/util/concurrent/testing/MockFutureListener.java
index fc3ed21f1ba9..a2fe4f447a79 100644
--- a/android/guava-testlib/src/com/google/common/util/concurrent/testing/MockFutureListener.java
+++ b/android/guava-testlib/src/com/google/common/util/concurrent/testing/MockFutureListener.java
@@ -17,13 +17,13 @@
 package com.google.common.util.concurrent.testing;
 
 import static com.google.common.util.concurrent.MoreExecutors.directExecutor;
+import static java.util.concurrent.TimeUnit.SECONDS;
 
 import com.google.common.annotations.Beta;
 import com.google.common.annotations.GwtIncompatible;
 import com.google.common.util.concurrent.ListenableFuture;
 import java.util.concurrent.CountDownLatch;
 import java.util.concurrent.ExecutionException;
-import java.util.concurrent.TimeUnit;
 import junit.framework.Assert;
 
 /**
@@ -59,7 +59,7 @@ public void run() {
    */
   public void assertSuccess(Object expectedData) throws Throwable {
     // Verify that the listener executed in a reasonable amount of time.
-    Assert.assertTrue(countDownLatch.await(1L, TimeUnit.SECONDS));
+    Assert.assertTrue(countDownLatch.await(1L, SECONDS));
 
     try {
       Assert.assertEquals(expectedData, future.get());
@@ -75,7 +75,7 @@ public void assertSuccess(Object expectedData) throws Throwable {
    */
   public void assertException(Throwable expectedCause) throws Exception {
     // Verify that the listener executed in a reasonable amount of time.
-    Assert.assertTrue(countDownLatch.await(1L, TimeUnit.SECONDS));
+    Assert.assertTrue(countDownLatch.await(1L, SECONDS));
 
     try {
       future.get();
@@ -88,6 +88,6 @@ public void assertException(Throwable expectedCause) throws Exception {
   public void assertTimeout() throws Exception {
     // Verify that the listener does not get called in a reasonable amount of
     // time.
-    Assert.assertFalse(countDownLatch.await(1L, TimeUnit.SECONDS));
+    Assert.assertFalse(countDownLatch.await(1L, SECONDS));
   }
 }
diff --git a/android/guava-testlib/src/com/google/common/util/concurrent/testing/SameThreadScheduledExecutorService.java b/android/guava-testlib/src/com/google/common/util/concurrent/testing/SameThreadScheduledExecutorService.java
index c232218fb4bf..25b7ef791c00 100644
--- a/android/guava-testlib/src/com/google/common/util/concurrent/testing/SameThreadScheduledExecutorService.java
+++ b/android/guava-testlib/src/com/google/common/util/concurrent/testing/SameThreadScheduledExecutorService.java
@@ -140,11 +140,11 @@ public ListenableScheduledFuture<?> schedule(Runnable command, long delay, TimeU
 
   @Override
   public <V> ListenableScheduledFuture<V> schedule(
-      final Callable<V> callable, long delay, TimeUnit unit) {
+      Callable<V> callable, long delay, TimeUnit unit) {
     Preconditions.checkNotNull(callable, "callable must not be null!");
     Preconditions.checkNotNull(unit, "unit must not be null!");
     ListenableFuture<V> delegateFuture = submit(callable);
-    return new ImmediateScheduledFuture<V>(delegateFuture);
+    return new ImmediateScheduledFuture<>(delegateFuture);
   }
 
   private static class ImmediateScheduledFuture<V> extends SimpleForwardingListenableFuture<V>
diff --git a/android/guava-testlib/src/com/google/common/util/concurrent/testing/TestingExecutors.java b/android/guava-testlib/src/com/google/common/util/concurrent/testing/TestingExecutors.java
index 421243043245..dc2c40d37492 100644
--- a/android/guava-testlib/src/com/google/common/util/concurrent/testing/TestingExecutors.java
+++ b/android/guava-testlib/src/com/google/common/util/concurrent/testing/TestingExecutors.java
@@ -16,6 +16,8 @@
 
 package com.google.common.util.concurrent.testing;
 
+import static java.util.concurrent.TimeUnit.NANOSECONDS;
+
 import com.google.common.annotations.Beta;
 import com.google.common.annotations.GwtIncompatible;
 import com.google.common.collect.ImmutableList;
@@ -153,7 +155,7 @@ private static class NeverScheduledFuture<V> extends AbstractFuture<V>
         implements ListenableScheduledFuture<V> {
 
       static <V> NeverScheduledFuture<V> create() {
-        return new NeverScheduledFuture<V>();
+        return new NeverScheduledFuture<>();
       }
 
       @Override
@@ -163,7 +165,7 @@ public long getDelay(TimeUnit unit) {
 
       @Override
       public int compareTo(Delayed other) {
-        return Longs.compare(getDelay(TimeUnit.NANOSECONDS), other.getDelay(TimeUnit.NANOSECONDS));
+        return Longs.compare(getDelay(NANOSECONDS), other.getDelay(NANOSECONDS));
       }
     }
   }
diff --git a/android/guava-testlib/test/com/google/common/collect/testing/FeatureSpecificTestSuiteBuilderTest.java b/android/guava-testlib/test/com/google/common/collect/testing/FeatureSpecificTestSuiteBuilderTest.java
index dc0fe37b4471..4d617d64db09 100644
--- a/android/guava-testlib/test/com/google/common/collect/testing/FeatureSpecificTestSuiteBuilderTest.java
+++ b/android/guava-testlib/test/com/google/common/collect/testing/FeatureSpecificTestSuiteBuilderTest.java
@@ -27,7 +27,7 @@
 /** @author Max Ross */
 public class FeatureSpecificTestSuiteBuilderTest extends TestCase {
 
-  static boolean testWasRun;
+  private static boolean testWasRun;
 
   @Override
   protected void setUp() throws Exception {
@@ -52,7 +52,7 @@ protected List<Class<? extends AbstractTester>> getTesters() {
   }
 
   public void testLifecycle() {
-    final boolean setUp[] = {false};
+    boolean[] setUp = {false};
     Runnable setUpRunnable =
         new Runnable() {
           @Override
@@ -61,7 +61,7 @@ public void run() {
           }
         };
 
-    final boolean tearDown[] = {false};
+    boolean[] tearDown = {false};
     Runnable tearDownRunnable =
         new Runnable() {
           @Override
diff --git a/android/guava-testlib/test/com/google/common/collect/testing/MapTestSuiteBuilderTests.java b/android/guava-testlib/test/com/google/common/collect/testing/MapTestSuiteBuilderTests.java
index 1a54f6862ded..a4d216d1503c 100644
--- a/android/guava-testlib/test/com/google/common/collect/testing/MapTestSuiteBuilderTests.java
+++ b/android/guava-testlib/test/com/google/common/collect/testing/MapTestSuiteBuilderTests.java
@@ -26,6 +26,11 @@
 import com.google.common.collect.testing.features.CollectionSize;
 import com.google.common.collect.testing.features.Feature;
 import com.google.common.collect.testing.features.MapFeature;
+import com.google.common.reflect.Reflection;
+import java.io.Serializable;
+import java.lang.reflect.InvocationHandler;
+import java.lang.reflect.InvocationTargetException;
+import java.lang.reflect.Method;
 import java.util.AbstractMap;
 import java.util.AbstractSet;
 import java.util.Collection;
@@ -36,6 +41,7 @@
 import java.util.Map;
 import java.util.Map.Entry;
 import java.util.Set;
+import java.util.concurrent.atomic.AtomicBoolean;
 import junit.framework.Test;
 import junit.framework.TestCase;
 import junit.framework.TestSuite;
@@ -52,6 +58,7 @@ public static Test suite() {
     TestSuite suite = new TestSuite(MapTestSuiteBuilderTests.class.getSimpleName());
     suite.addTest(testsForHashMapNullKeysForbidden());
     suite.addTest(testsForHashMapNullValuesForbidden());
+    suite.addTest(testsForSetUpTearDown());
     return suite;
   }
 
@@ -252,4 +259,89 @@ public String put(String key, String value) {
         "HashMap w/out null values",
         ALLOWS_NULL_KEYS);
   }
+
+  /**
+   * Map generator that verifies that {@code setUp()} methods are called in all the test cases. The
+   * {@code setUpRan} parameter is set true by the {@code setUp} that every test case is supposed to
+   * have registered, and set false by the {@code tearDown}. We use a dynamic proxy to intercept all
+   * of the {@code Map} method calls and check that {@code setUpRan} is true.
+   */
+  private static class CheckSetUpHashMapGenerator extends WrappedHashMapGenerator {
+    private final AtomicBoolean setUpRan;
+
+    CheckSetUpHashMapGenerator(AtomicBoolean setUpRan) {
+      this.setUpRan = setUpRan;
+    }
+
+    @Override
+    Map<String, String> wrap(HashMap<String, String> map) {
+      @SuppressWarnings("unchecked")
+      Map<String, String> proxy =
+          Reflection.newProxy(Map.class, new CheckSetUpInvocationHandler(map, setUpRan));
+      return proxy;
+    }
+  }
+
+  /**
+   * Intercepts calls to a {@code Map} to check that {@code setUpRan} is true when they happen. Then
+   * forwards the calls to the underlying {@code Map}.
+   */
+  private static class CheckSetUpInvocationHandler implements InvocationHandler, Serializable {
+    private final Map<String, String> map;
+    private final AtomicBoolean setUpRan;
+
+    CheckSetUpInvocationHandler(Map<String, String> map, AtomicBoolean setUpRan) {
+      this.map = map;
+      this.setUpRan = setUpRan;
+    }
+
+    @Override
+    public Object invoke(Object target, Method method, Object[] args) throws Throwable {
+      assertTrue("setUp should have run", setUpRan.get());
+      try {
+        return method.invoke(map, args);
+      } catch (InvocationTargetException e) {
+        throw e.getCause();
+      } catch (IllegalAccessException e) {
+        throw newLinkageError(e);
+      }
+    }
+  }
+
+  /** Verifies that {@code setUp} and {@code tearDown} are called in all map test cases. */
+  private static Test testsForSetUpTearDown() {
+    final AtomicBoolean setUpRan = new AtomicBoolean();
+    Runnable setUp =
+        new Runnable() {
+          @Override
+          public void run() {
+            assertFalse("previous tearDown should have run before setUp", setUpRan.getAndSet(true));
+          }
+        };
+    Runnable tearDown =
+        new Runnable() {
+          @Override
+          public void run() {
+            assertTrue("setUp should have run", setUpRan.getAndSet(false));
+          }
+        };
+    return MapTestSuiteBuilder.using(new CheckSetUpHashMapGenerator(setUpRan))
+        .named("setUpTearDown")
+        .withFeatures(
+            MapFeature.GENERAL_PURPOSE,
+            MapFeature.ALLOWS_NULL_KEYS,
+            MapFeature.ALLOWS_NULL_VALUES,
+            CollectionFeature.SERIALIZABLE,
+            CollectionFeature.SUPPORTS_ITERATOR_REMOVE,
+            CollectionSize.ANY)
+        .withSetUp(setUp)
+        .withTearDown(tearDown)
+        .createTestSuite();
+  }
+
+  private static LinkageError newLinkageError(Throwable cause) {
+    LinkageError error = new LinkageError(cause.toString());
+    error.initCause(cause);
+    return error;
+  }
 }
diff --git a/android/guava-testlib/test/com/google/common/testing/ClassSanityTesterTest.java b/android/guava-testlib/test/com/google/common/testing/ClassSanityTesterTest.java
index 586eb284eb91..be1752d4793a 100644
--- a/android/guava-testlib/test/com/google/common/testing/ClassSanityTesterTest.java
+++ b/android/guava-testlib/test/com/google/common/testing/ClassSanityTesterTest.java
@@ -34,9 +34,9 @@
 import java.util.Map;
 import java.util.Set;
 import java.util.concurrent.TimeUnit;
+import javax.annotation.CheckForNull;
 import junit.framework.AssertionFailedError;
 import junit.framework.TestCase;
-import org.checkerframework.checker.nullness.compatqual.NullableDecl;
 
 /**
  * Unit tests for {@link ClassSanityTester}.
@@ -58,7 +58,7 @@ public static Object good(
         // oneConstantOnly doesn't matter since it's not nullable and can be only 1 value.
         @SuppressWarnings("unused") OneConstantEnum oneConstantOnly,
         // noConstant doesn't matter since it can only be null
-        @SuppressWarnings("unused") @NullableDecl NoConstantEnum noConstant) {
+        @SuppressWarnings("unused") @CheckForNull NoConstantEnum noConstant) {
       return new GoodEquals(a, b);
     }
     // instance method ignored
@@ -106,7 +106,7 @@ public void testEqualsOnReturnValues_bad() throws Exception {
   private static class BadEqualsFactory {
     /** oneConstantOnly matters now since it can be either null or the constant. */
     @SuppressWarnings("unused") // Called by reflection
-    public static Object bad(String a, int b, @NullableDecl OneConstantEnum oneConstantOnly) {
+    public static Object bad(String a, int b, @CheckForNull OneConstantEnum oneConstantOnly) {
       return new GoodEquals(a, b);
     }
   }
@@ -287,7 +287,7 @@ public void testEqualsAndSerializableForReturnValues_factoryReturnsNullAndAnnota
   }
 
   public static class FactoryThatReturnsNullAndAnnotated {
-    @NullableDecl
+    @CheckForNull
     public static Object bad() {
       return null;
     }
@@ -616,7 +616,7 @@ public HasAnInterface(AnInterface i) {
     }
 
     @Override
-    public boolean equals(@NullableDecl Object obj) {
+    public boolean equals(@CheckForNull Object obj) {
       if (obj instanceof HasAnInterface) {
         HasAnInterface that = (HasAnInterface) obj;
         return i.equals(that.i);
@@ -673,7 +673,7 @@ private abstract static class Wrapper {
     }
 
     @Override
-    public boolean equals(@NullableDecl Object obj) {
+    public boolean equals(@CheckForNull Object obj) {
       // In general getClass().isInstance() is bad for equals.
       // But here we fully control the subclasses to ensure symmetry.
       if (getClass().isInstance(obj)) {
@@ -753,13 +753,13 @@ static GoodEquals create(String a, int b) {
 
     // keep trying
     @SuppressWarnings("unused")
-    @NullableDecl
+    @CheckForNull
     public static GoodEquals createMayReturnNull(int a, int b) {
       return null;
     }
 
     @Override
-    public boolean equals(@NullableDecl Object obj) {
+    public boolean equals(@CheckForNull Object obj) {
       if (obj instanceof GoodEquals) {
         GoodEquals that = (GoodEquals) obj;
         return a.equals(that.a) && b == that.b;
@@ -778,12 +778,12 @@ static class BadEquals {
 
     public BadEquals() {} // ignored by testEquals() since it has less parameters.
 
-    public static BadEquals create(@SuppressWarnings("unused") @NullableDecl String s) {
+    public static BadEquals create(@SuppressWarnings("unused") @CheckForNull String s) {
       return new BadEquals();
     }
 
     @Override
-    public boolean equals(@NullableDecl Object obj) {
+    public boolean equals(@CheckForNull Object obj) {
       return obj instanceof BadEquals;
     }
 
@@ -1122,7 +1122,7 @@ public static BadEqualsWithParameterizedType create(
     }
 
     @Override
-    public boolean equals(@NullableDecl Object obj) {
+    public boolean equals(@CheckForNull Object obj) {
       return obj instanceof BadEqualsWithParameterizedType;
     }
 
@@ -1156,12 +1156,12 @@ public NoNullCheckNeededDespitNotInstantiable(NotInstantiable x) {
     void primitiveOnly(int i) {}
 
     @SuppressWarnings("unused") // reflected
-    void nullableOnly(@NullableDecl String s) {}
+    void nullableOnly(@CheckForNull String s) {}
 
     public void noParameter() {}
 
     @SuppressWarnings("unused") // reflected
-    void primitiveAndNullable(@NullableDecl String s, int i) {}
+    void primitiveAndNullable(@CheckForNull String s, int i) {}
   }
 
   static class FactoryMethodReturnsNullButNotAnnotated {
@@ -1175,7 +1175,7 @@ static FactoryMethodReturnsNullButNotAnnotated returnsNull() {
   static class FactoryMethodReturnsNullAndAnnotated {
     private FactoryMethodReturnsNullAndAnnotated() {}
 
-    @NullableDecl
+    @CheckForNull
     public static FactoryMethodReturnsNullAndAnnotated returnsNull() {
       return null;
     }
@@ -1189,7 +1189,7 @@ private FactoryMethodAcceptsNull(String name) {
       this.name = name;
     }
 
-    static FactoryMethodAcceptsNull create(@NullableDecl String name) {
+    static FactoryMethodAcceptsNull create(@CheckForNull String name) {
       return new FactoryMethodAcceptsNull(name);
     }
   }
@@ -1211,7 +1211,7 @@ static class ConstructorAcceptsNull {
 
     final String name;
 
-    public ConstructorAcceptsNull(@NullableDecl String name) {
+    public ConstructorAcceptsNull(@CheckForNull String name) {
       this.name = name;
     }
   }
@@ -1237,7 +1237,7 @@ public ConstructorParameterMapOfNotInstantiable(Map<NotInstantiable, NotInstanti
     }
 
     @Override
-    public boolean equals(@NullableDecl Object obj) {
+    public boolean equals(@CheckForNull Object obj) {
       if (obj instanceof ConstructorParameterMapOfNotInstantiable) {
         return m.equals(((ConstructorParameterMapOfNotInstantiable) obj).m);
       } else {
@@ -1258,7 +1258,7 @@ public ConstructorParameterWithOptionalNotInstantiable(Optional<NotInstantiable>
     }
 
     @Override
-    public boolean equals(@NullableDecl Object obj) {
+    public boolean equals(@CheckForNull Object obj) {
       throw new UnsupportedOperationException();
     }
 
diff --git a/android/guava-testlib/test/com/google/common/testing/EquivalenceTesterTest.java b/android/guava-testlib/test/com/google/common/testing/EquivalenceTesterTest.java
index d612b2c2c876..865c198e727f 100644
--- a/android/guava-testlib/test/com/google/common/testing/EquivalenceTesterTest.java
+++ b/android/guava-testlib/test/com/google/common/testing/EquivalenceTesterTest.java
@@ -237,7 +237,7 @@ void expectHash(Object object, int hash) {
     void replay() {
       checkRecording();
       equivalentExpectations = equivalentExpectationsBuilder.build();
-      hashExpectations = hashExpectationsBuilder.build();
+      hashExpectations = hashExpectationsBuilder.buildOrThrow();
     }
 
     @Override
diff --git a/android/guava-testlib/test/com/google/common/testing/NullPointerTesterTest.java b/android/guava-testlib/test/com/google/common/testing/NullPointerTesterTest.java
index d1dc49bf165b..218edef0a632 100644
--- a/android/guava-testlib/test/com/google/common/testing/NullPointerTesterTest.java
+++ b/android/guava-testlib/test/com/google/common/testing/NullPointerTesterTest.java
@@ -44,9 +44,9 @@
 import java.util.Map;
 import java.util.Set;
 import java.util.SortedSet;
+import javax.annotation.CheckForNull;
 import junit.framework.AssertionFailedError;
 import junit.framework.TestCase;
-import org.checkerframework.checker.nullness.compatqual.NullableDecl;
 
 /**
  * Unit test for {@link NullPointerTester}.
@@ -86,11 +86,11 @@ public static void staticOneArgCheckForNullCorrectlyDoesNotThrowNPE(
       // null?  no problem
     }
 
-    public static void staticOneArgJsr305NullableCorrectlyDoesNotThrowNPE(@NullableDecl String s) {
+    public static void staticOneArgJsr305NullableCorrectlyDoesNotThrowNPE(@CheckForNull String s) {
       // null?  no problem
     }
 
-    public static void staticOneArgNullableCorrectlyDoesNotThrowNPE(@NullableDecl String s) {
+    public static void staticOneArgNullableCorrectlyDoesNotThrowNPE(@CheckForNull String s) {
       // null?  no problem
     }
 
@@ -99,7 +99,7 @@ public static void staticOneArgCheckForNullCorrectlyThrowsOtherThanNPE(
       throw new FooException(); // ok, as long as it's not NullPointerException
     }
 
-    public static void staticOneArgNullableCorrectlyThrowsOtherThanNPE(@NullableDecl String s) {
+    public static void staticOneArgNullableCorrectlyThrowsOtherThanNPE(@CheckForNull String s) {
       throw new FooException(); // ok, as long as it's not NullPointerException
     }
 
@@ -107,7 +107,7 @@ public static void staticOneArgCheckForNullThrowsNPE(@javax.annotation.CheckForN
       checkNotNull(s); // doesn't check if you said you'd accept null, but you don't
     }
 
-    public static void staticOneArgNullableThrowsNPE(@NullableDecl String s) {
+    public static void staticOneArgNullableThrowsNPE(@CheckForNull String s) {
       checkNotNull(s); // doesn't check if you said you'd accept null, but you don't
     }
 
@@ -128,7 +128,7 @@ public void oneArgCheckForNullCorrectlyDoesNotThrowNPE(
       // null?  no problem
     }
 
-    public void oneArgNullableCorrectlyDoesNotThrowNPE(@NullableDecl String s) {
+    public void oneArgNullableCorrectlyDoesNotThrowNPE(@CheckForNull String s) {
       // null?  no problem
     }
 
@@ -137,7 +137,7 @@ public void oneArgCheckForNullCorrectlyThrowsOtherThanNPE(
       throw new FooException(); // ok, as long as it's not NullPointerException
     }
 
-    public void oneArgNullableCorrectlyThrowsOtherThanNPE(@NullableDecl String s) {
+    public void oneArgNullableCorrectlyThrowsOtherThanNPE(@CheckForNull String s) {
       throw new FooException(); // ok, as long as it's not NullPointerException
     }
 
@@ -145,7 +145,7 @@ public void oneArgCheckForNullThrowsNPE(@javax.annotation.CheckForNull String s)
       checkNotNull(s); // doesn't check if you said you'd accept null, but you don't
     }
 
-    public void oneArgNullableThrowsNPE(@NullableDecl String s) {
+    public void oneArgNullableThrowsNPE(@CheckForNull String s) {
       checkNotNull(s); // doesn't check if you said you'd accept null, but you don't
     }
   }
@@ -347,19 +347,19 @@ public void normalNormal(String first, Integer second) {
 
     /** Two-arg method with the second param Nullable. */
     @SuppressWarnings("GoodTime") // false positive; b/122617528
-    public void normalNullable(String first, @NullableDecl Integer second) {
+    public void normalNullable(String first, @CheckForNull Integer second) {
       reactToNullParameters(first, second);
     }
 
     /** Two-arg method with the first param Nullable. */
     @SuppressWarnings("GoodTime") // false positive; b/122617528
-    public void nullableNormal(@NullableDecl String first, Integer second) {
+    public void nullableNormal(@CheckForNull String first, Integer second) {
       reactToNullParameters(first, second);
     }
 
     /** Two-arg method with the both params Nullable. */
     @SuppressWarnings("GoodTime") // false positive; b/122617528
-    public void nullableNullable(@NullableDecl String first, @NullableDecl Integer second) {
+    public void nullableNullable(@CheckForNull String first, @CheckForNull Integer second) {
       reactToNullParameters(first, second);
     }
 
@@ -473,9 +473,9 @@ protected void protectedOneArg(String s) {
       checkNotNull(s);
     }
 
-    public void oneNullableArg(@NullableDecl String s) {}
+    public void oneNullableArg(@CheckForNull String s) {}
 
-    public void oneNullableArgThrows(@NullableDecl String s) {
+    public void oneNullableArgThrows(@CheckForNull String s) {
       doThrow(s);
     }
 
@@ -484,31 +484,31 @@ public void twoArg(String s, Integer i) {
       i.intValue();
     }
 
-    public void twoMixedArgs(String s, @NullableDecl Integer i) {
+    public void twoMixedArgs(String s, @CheckForNull Integer i) {
       checkNotNull(s);
     }
 
-    public void twoMixedArgs(@NullableDecl Integer i, String s) {
+    public void twoMixedArgs(@CheckForNull Integer i, String s) {
       checkNotNull(s);
     }
 
-    public void twoMixedArgsThrows(String s, @NullableDecl Integer i) {
+    public void twoMixedArgsThrows(String s, @CheckForNull Integer i) {
       checkNotNull(s);
       doThrow(i);
     }
 
-    public void twoMixedArgsThrows(@NullableDecl Integer i, String s) {
+    public void twoMixedArgsThrows(@CheckForNull Integer i, String s) {
       checkNotNull(s);
       doThrow(i);
     }
 
-    public void twoNullableArgs(@NullableDecl String s, @NullableDecl Integer i) {}
+    public void twoNullableArgs(@CheckForNull String s, @CheckForNull Integer i) {}
 
-    public void twoNullableArgsThrowsFirstArg(@NullableDecl String s, @NullableDecl Integer i) {
+    public void twoNullableArgsThrowsFirstArg(@CheckForNull String s, @CheckForNull Integer i) {
       doThrow(s);
     }
 
-    public void twoNullableArgsThrowsSecondArg(@NullableDecl String s, @NullableDecl Integer i) {
+    public void twoNullableArgsThrowsSecondArg(@CheckForNull String s, @CheckForNull Integer i) {
       doThrow(i);
     }
 
@@ -516,9 +516,9 @@ public static void staticOneArg(String s) {
       checkNotNull(s);
     }
 
-    public static void staticOneNullableArg(@NullableDecl String s) {}
+    public static void staticOneNullableArg(@CheckForNull String s) {}
 
-    public static void staticOneNullableArgThrows(@NullableDecl String s) {
+    public static void staticOneNullableArgThrows(@CheckForNull String s) {
       doThrow(s);
     }
   }
@@ -551,7 +551,7 @@ public void testFailOneArgThrowsWrongType() {
 
   private static class PassOneNullableArgThrowsNPE extends PassObject {
     @Override
-    public void oneNullableArg(@NullableDecl String s) {
+    public void oneNullableArg(@CheckForNull String s) {
       checkNotNull(s); // ok to throw NPE
     }
   }
@@ -610,7 +610,7 @@ public void testFailTwoArgsSecondArgThrowsWrongType() {
 
   private static class FailTwoMixedArgsFirstArgDoesntThrowNPE extends PassObject {
     @Override
-    public void twoMixedArgs(String s, @NullableDecl Integer i) {
+    public void twoMixedArgs(String s, @CheckForNull Integer i) {
       // Fail: missing NPE for s
     }
   }
@@ -621,7 +621,7 @@ public void testFailTwoMixedArgsFirstArgDoesntThrowNPE() {
 
   private static class FailTwoMixedArgsFirstArgThrowsWrongType extends PassObject {
     @Override
-    public void twoMixedArgs(String s, @NullableDecl Integer i) {
+    public void twoMixedArgs(String s, @CheckForNull Integer i) {
       doThrow(s); // Fail:  throwing non-NPE exception for null s
     }
   }
@@ -632,7 +632,7 @@ public void testFailTwoMixedArgsFirstArgThrowsWrongType() {
 
   private static class PassTwoMixedArgsNullableArgThrowsNPE extends PassObject {
     @Override
-    public void twoMixedArgs(String s, @NullableDecl Integer i) {
+    public void twoMixedArgs(String s, @CheckForNull Integer i) {
       checkNotNull(s);
       i.intValue(); // ok to throw NPE?
     }
@@ -644,7 +644,7 @@ public void testPassTwoMixedArgsNullableArgThrowsNPE() {
 
   private static class PassTwoMixedArgSecondNullableArgThrowsOther extends PassObject {
     @Override
-    public void twoMixedArgs(String s, @NullableDecl Integer i) {
+    public void twoMixedArgs(String s, @CheckForNull Integer i) {
       checkNotNull(s);
       doThrow(i); // ok to throw non-NPE exception for null i
     }
@@ -656,7 +656,7 @@ public void testPassTwoMixedArgSecondNullableArgThrowsOther() {
 
   private static class FailTwoMixedArgsSecondArgDoesntThrowNPE extends PassObject {
     @Override
-    public void twoMixedArgs(@NullableDecl Integer i, String s) {
+    public void twoMixedArgs(@CheckForNull Integer i, String s) {
       // Fail: missing NPE for null s
     }
   }
@@ -667,7 +667,7 @@ public void testFailTwoMixedArgsSecondArgDoesntThrowNPE() {
 
   private static class FailTwoMixedArgsSecondArgThrowsWrongType extends PassObject {
     @Override
-    public void twoMixedArgs(@NullableDecl Integer i, String s) {
+    public void twoMixedArgs(@CheckForNull Integer i, String s) {
       doThrow(s); // Fail:  throwing non-NPE exception for null s
     }
   }
@@ -678,7 +678,7 @@ public void testFailTwoMixedArgsSecondArgThrowsWrongType() {
 
   private static class PassTwoNullableArgsFirstThrowsNPE extends PassObject {
     @Override
-    public void twoNullableArgs(@NullableDecl String s, @NullableDecl Integer i) {
+    public void twoNullableArgs(@CheckForNull String s, @CheckForNull Integer i) {
       checkNotNull(s); // ok to throw NPE?
     }
   }
@@ -689,7 +689,7 @@ public void testPassTwoNullableArgsFirstThrowsNPE() {
 
   private static class PassTwoNullableArgsFirstThrowsOther extends PassObject {
     @Override
-    public void twoNullableArgs(@NullableDecl String s, @NullableDecl Integer i) {
+    public void twoNullableArgs(@CheckForNull String s, @CheckForNull Integer i) {
       doThrow(s); // ok to throw non-NPE exception for null s
     }
   }
@@ -700,7 +700,7 @@ public void testPassTwoNullableArgsFirstThrowsOther() {
 
   private static class PassTwoNullableArgsSecondThrowsNPE extends PassObject {
     @Override
-    public void twoNullableArgs(@NullableDecl String s, @NullableDecl Integer i) {
+    public void twoNullableArgs(@CheckForNull String s, @CheckForNull Integer i) {
       i.intValue(); // ok to throw NPE?
     }
   }
@@ -711,7 +711,7 @@ public void testPassTwoNullableArgsSecondThrowsNPE() {
 
   private static class PassTwoNullableArgsSecondThrowsOther extends PassObject {
     @Override
-    public void twoNullableArgs(@NullableDecl String s, @NullableDecl Integer i) {
+    public void twoNullableArgs(@CheckForNull String s, @CheckForNull Integer i) {
       doThrow(i); // ok to throw non-NPE exception for null i
     }
   }
@@ -722,7 +722,7 @@ public void testPassTwoNullableArgsSecondThrowsOther() {
 
   private static class PassTwoNullableArgsNeitherThrowsAnything extends PassObject {
     @Override
-    public void twoNullableArgs(@NullableDecl String s, @NullableDecl Integer i) {
+    public void twoNullableArgs(@CheckForNull String s, @CheckForNull Integer i) {
       // ok to do nothing
     }
   }
@@ -768,7 +768,7 @@ public void testSubclassWithBadSuperclassForPackageProtectedMethod() {
 
   private static class SubclassThatOverridesBadSuperclassMethod extends BaseClassThatFailsToThrow {
     @Override
-    public void oneArg(@NullableDecl String s) {}
+    public void oneArg(@CheckForNull String s) {}
   }
 
   public void testSubclassThatOverridesBadSuperclassMethod() {
@@ -777,7 +777,7 @@ public void testSubclassThatOverridesBadSuperclassMethod() {
 
   @SuppressWarnings("unused") // for NullPointerTester
   private static class SubclassOverridesTheWrongMethod extends BaseClassThatFailsToThrow {
-    public void oneArg(@NullableDecl CharSequence s) {}
+    public void oneArg(@CheckForNull CharSequence s) {}
   }
 
   public void testSubclassOverridesTheWrongMethod() {
@@ -801,7 +801,7 @@ public void testSubclassThatFailsToThrowForStatic() {
 
   private static class SubclassThatTriesToOverrideBadStaticMethod
       extends ClassThatFailsToThrowForStatic {
-    static void staticOneArg(@NullableDecl String s) {}
+    static void staticOneArg(@CheckForNull String s) {}
   }
 
   public void testSubclassThatTriesToOverrideBadStaticMethod() {
@@ -814,7 +814,7 @@ private HardToCreate(HardToCreate x) {}
 
   @SuppressWarnings("unused") // used by reflection
   private static class CanCreateDefault {
-    public void foo(@NullableDecl HardToCreate ignored, String required) {
+    public void foo(@CheckForNull HardToCreate ignored, String required) {
       checkNotNull(required);
     }
   }
@@ -877,7 +877,7 @@ private static void shouldFail(Class<?> cls) {
 
   @SuppressWarnings("unused") // used by reflection
   private static class PrivateClassWithPrivateConstructor {
-    private PrivateClassWithPrivateConstructor(@NullableDecl Integer argument) {}
+    private PrivateClassWithPrivateConstructor(@CheckForNull Integer argument) {}
   }
 
   public void testPrivateClass() {
diff --git a/android/guava-tests/benchmark/com/google/common/base/StringsRepeatBenchmark.java b/android/guava-tests/benchmark/com/google/common/base/StringsRepeatBenchmark.java
index 30261da5d8ff..16e00ef3d2e2 100644
--- a/android/guava-tests/benchmark/com/google/common/base/StringsRepeatBenchmark.java
+++ b/android/guava-tests/benchmark/com/google/common/base/StringsRepeatBenchmark.java
@@ -40,7 +40,7 @@ void setUp() {
   }
 
   @Benchmark
-  void oldRepeat(int reps) {
+  void oldRepeat(long reps) {
     for (int i = 0; i < reps; i++) {
       String x = oldRepeat(originalString, count);
       if (x.length() != (originalString.length() * count)) {
@@ -62,7 +62,7 @@ private static String oldRepeat(String string, int count) {
   }
 
   @Benchmark
-  void mikeRepeat(int reps) {
+  void mikeRepeat(long reps) {
     for (int i = 0; i < reps; i++) {
       String x = mikeRepeat(originalString, count);
       if (x.length() != (originalString.length() * count)) {
@@ -95,7 +95,7 @@ private static String mikeRepeat(String string, int count) {
   }
 
   @Benchmark
-  void martinRepeat(int reps) {
+  void martinRepeat(long reps) {
     for (int i = 0; i < reps; i++) {
       String x = martinRepeat(originalString, count);
       if (x.length() != (originalString.length() * count)) {
diff --git a/android/guava-tests/benchmark/com/google/common/base/ToStringHelperBenchmark.java b/android/guava-tests/benchmark/com/google/common/base/ToStringHelperBenchmark.java
index 2d7a447272b1..47dd8f46a154 100644
--- a/android/guava-tests/benchmark/com/google/common/base/ToStringHelperBenchmark.java
+++ b/android/guava-tests/benchmark/com/google/common/base/ToStringHelperBenchmark.java
@@ -136,4 +136,6 @@ int toString(int reps) {
     }
     return dummy;
   }
+
+  // When omitEmptyValues() is released, remove this method and add a new @Param "omitEmptyValues".
 }
diff --git a/android/guava-tests/benchmark/com/google/common/collect/ConcurrentHashMultisetBenchmark.java b/android/guava-tests/benchmark/com/google/common/collect/ConcurrentHashMultisetBenchmark.java
index 5b713f26b64f..086a634932f3 100644
--- a/android/guava-tests/benchmark/com/google/common/collect/ConcurrentHashMultisetBenchmark.java
+++ b/android/guava-tests/benchmark/com/google/common/collect/ConcurrentHashMultisetBenchmark.java
@@ -37,7 +37,7 @@
 import java.util.concurrent.ExecutorService;
 import java.util.concurrent.Executors;
 import java.util.concurrent.Future;
-import org.checkerframework.checker.nullness.compatqual.NullableDecl;
+import javax.annotation.CheckForNull;
 
 /**
  * Benchmarks for {@link ConcurrentHashMultiset}.
@@ -192,7 +192,7 @@ public static <E> OldConcurrentHashMultiset<E> create() {
      * @return the nonnegative number of occurrences of the element
      */
     @Override
-    public int count(@NullableDecl Object element) {
+    public int count(@CheckForNull Object element) {
       try {
         return unbox(countMap.get(element));
       } catch (NullPointerException | ClassCastException e) {
@@ -295,7 +295,7 @@ public int add(E element, int occurrences) {
      * @throws IllegalArgumentException if {@code occurrences} is negative
      */
     @Override
-    public int remove(@NullableDecl Object element, int occurrences) {
+    public int remove(@CheckForNull Object element, int occurrences) {
       if (occurrences == 0) {
         return count(element);
       }
@@ -330,7 +330,7 @@ public int remove(@NullableDecl Object element, int occurrences) {
      * @param element the element whose occurrences should all be removed
      * @return the number of occurrences successfully removed, possibly zero
      */
-    private int removeAllOccurrences(@NullableDecl Object element) {
+    private int removeAllOccurrences(@CheckForNull Object element) {
       try {
         return unbox(countMap.remove(element));
       } catch (NullPointerException | ClassCastException e) {
@@ -349,7 +349,7 @@ private int removeAllOccurrences(@NullableDecl Object element) {
      * @param occurrences the number of occurrences of {@code element} to remove
      * @return {@code true} if the removal was possible (including if {@code occurrences} is zero)
      */
-    public boolean removeExactly(@NullableDecl Object element, int occurrences) {
+    public boolean removeExactly(@CheckForNull Object element, int occurrences) {
       if (occurrences == 0) {
         return true;
       }
@@ -543,7 +543,7 @@ public int hashCode() {
     }
 
     /** We use a special form of unboxing that treats null as zero. */
-    private static int unbox(@NullableDecl Integer i) {
+    private static int unbox(@CheckForNull Integer i) {
       return (i == null) ? 0 : i;
     }
   }
diff --git a/android/guava-tests/benchmark/com/google/common/collect/MapBenchmark.java b/android/guava-tests/benchmark/com/google/common/collect/MapBenchmark.java
index f10b94ea6e10..cd8e24b1ef76 100644
--- a/android/guava-tests/benchmark/com/google/common/collect/MapBenchmark.java
+++ b/android/guava-tests/benchmark/com/google/common/collect/MapBenchmark.java
@@ -139,7 +139,7 @@ Map<Element, Element> create(Collection<Element> keys) {
         for (Element element : keys) {
           builder.put(element, element);
         }
-        return builder.build();
+        return builder.buildOrThrow();
       }
     },
     ImmutableSorted {
diff --git a/android/guava-tests/benchmark/com/google/common/util/concurrent/ExecutionListBenchmark.java b/android/guava-tests/benchmark/com/google/common/util/concurrent/ExecutionListBenchmark.java
index c9df7748336e..22053c8d696a 100644
--- a/android/guava-tests/benchmark/com/google/common/util/concurrent/ExecutionListBenchmark.java
+++ b/android/guava-tests/benchmark/com/google/common/util/concurrent/ExecutionListBenchmark.java
@@ -38,7 +38,7 @@
 import java.util.concurrent.atomic.AtomicInteger;
 import java.util.logging.Level;
 import java.util.logging.Logger;
-import org.checkerframework.checker.nullness.compatqual.NullableDecl;
+import javax.annotation.CheckForNull;
 
 /** Benchmarks for {@link ExecutionList}. */
 @VmOptions({"-Xms8g", "-Xmx8g"})
@@ -488,7 +488,7 @@ private static void executeListener(Runnable runnable, Executor executor) {
     private static final class RunnableExecutorPair {
       final Runnable runnable;
       final Executor executor;
-      @NullableDecl RunnableExecutorPair next;
+      @CheckForNull RunnableExecutorPair next;
 
       RunnableExecutorPair(Runnable runnable, Executor executor, RunnableExecutorPair next) {
         this.runnable = runnable;
@@ -563,7 +563,7 @@ private static void executeListener(Runnable runnable, Executor executor) {
     private static final class RunnableExecutorPair {
       Runnable runnable;
       Executor executor;
-      @NullableDecl RunnableExecutorPair next;
+      @CheckForNull RunnableExecutorPair next;
 
       RunnableExecutorPair(Runnable runnable, Executor executor) {
         this.runnable = runnable;
@@ -669,7 +669,7 @@ private static class RunnableExecutorPair {
       final Runnable runnable;
       final Executor executor;
       // Volatile because this is written on one thread and read on another with no synchronization.
-      @NullableDecl volatile RunnableExecutorPair next;
+      @CheckForNull volatile RunnableExecutorPair next;
 
       RunnableExecutorPair(Runnable runnable, Executor executor) {
         this.runnable = runnable;
diff --git a/android/guava-tests/benchmark/com/google/common/util/concurrent/FuturesGetCheckedBenchmark.java b/android/guava-tests/benchmark/com/google/common/util/concurrent/FuturesGetCheckedBenchmark.java
index dd1883bcb053..9129bfc2a9f1 100644
--- a/android/guava-tests/benchmark/com/google/common/util/concurrent/FuturesGetCheckedBenchmark.java
+++ b/android/guava-tests/benchmark/com/google/common/util/concurrent/FuturesGetCheckedBenchmark.java
@@ -21,7 +21,6 @@
 import static com.google.common.util.concurrent.Futures.immediateFailedFuture;
 import static com.google.common.util.concurrent.Futures.immediateFuture;
 import static com.google.common.util.concurrent.FuturesGetChecked.checkExceptionClassValidity;
-import static com.google.common.util.concurrent.FuturesGetChecked.classValueValidator;
 import static com.google.common.util.concurrent.FuturesGetChecked.getChecked;
 import static com.google.common.util.concurrent.FuturesGetChecked.isCheckedException;
 import static com.google.common.util.concurrent.FuturesGetChecked.weakSetValidator;
@@ -34,7 +33,7 @@
 import java.io.IOException;
 import java.net.URISyntaxException;
 import java.security.GeneralSecurityException;
-import java.security.acl.NotOwnerException;
+import java.security.KeyException;
 import java.util.List;
 import java.util.TooManyListenersException;
 import java.util.concurrent.BrokenBarrierException;
@@ -52,7 +51,7 @@ private enum Validator {
     NON_CACHING_WITH_CONSTRUCTOR_CHECK(nonCachingWithConstructorCheckValidator()),
     NON_CACHING_WITHOUT_CONSTRUCTOR_CHECK(nonCachingWithoutConstructorCheckValidator()),
     WEAK_SET(weakSetValidator()),
-    CLASS_VALUE(classValueValidator());
+    ;
 
     final GetCheckedTypeValidator validator;
 
@@ -92,7 +91,7 @@ private enum ExceptionType {
           ExecutionException.class,
           GeneralSecurityException.class,
           InvalidPreferencesFormatException.class,
-          NotOwnerException.class,
+          KeyException.class,
           RefreshFailedException.class,
           TimeoutException.class,
           TooManyListenersException.class,
diff --git a/android/guava-tests/benchmark/com/google/common/util/concurrent/MonitorBasedArrayBlockingQueue.java b/android/guava-tests/benchmark/com/google/common/util/concurrent/MonitorBasedArrayBlockingQueue.java
index 7998a729f3b9..2233fb47d978 100644
--- a/android/guava-tests/benchmark/com/google/common/util/concurrent/MonitorBasedArrayBlockingQueue.java
+++ b/android/guava-tests/benchmark/com/google/common/util/concurrent/MonitorBasedArrayBlockingQueue.java
@@ -25,7 +25,7 @@
 import java.util.NoSuchElementException;
 import java.util.concurrent.BlockingQueue;
 import java.util.concurrent.TimeUnit;
-import org.checkerframework.checker.nullness.compatqual.NullableDecl;
+import javax.annotation.CheckForNull;
 
 /**
  * A bounded {@linkplain BlockingQueue blocking queue} backed by an array. This queue orders
@@ -36,12 +36,12 @@
  *
  * <p>This is a classic &quot;bounded buffer&quot;, in which a fixed-sized array holds elements
  * inserted by producers and extracted by consumers. Once created, the capacity cannot be increased.
- * Attempts to <tt>put</tt> an element into a full queue will result in the operation blocking;
- * attempts to <tt>take</tt> an element from an empty queue will similarly block.
+ * Attempts to {@code put} an element into a full queue will result in the operation blocking;
+ * attempts to {@code take} an element from an empty queue will similarly block.
  *
  * <p>This class supports an optional fairness policy for ordering waiting producer and consumer
  * threads. By default, this ordering is not guaranteed. However, a queue constructed with fairness
- * set to <tt>true</tt> grants threads access in FIFO order. Fairness generally decreases throughput
+ * set to {@code true} grants threads access in FIFO order. Fairness generally decreases throughput
  * but reduces variability and avoids starvation.
  *
  * <p>This class and its iterator implement all of the <em>optional</em> methods of the {@link
@@ -139,24 +139,24 @@ void removeAt(int i) {
   }
 
   /**
-   * Creates an <tt>MonitorBasedArrayBlockingQueue</tt> with the given (fixed) capacity and default
+   * Creates an {@code MonitorBasedArrayBlockingQueue} with the given (fixed) capacity and default
    * access policy.
    *
    * @param capacity the capacity of this queue
-   * @throws IllegalArgumentException if <tt>capacity</tt> is less than 1
+   * @throws IllegalArgumentException if {@code capacity} is less than 1
    */
   public MonitorBasedArrayBlockingQueue(int capacity) {
     this(capacity, false);
   }
 
   /**
-   * Creates an <tt>MonitorBasedArrayBlockingQueue</tt> with the given (fixed) capacity and the
+   * Creates an {@code MonitorBasedArrayBlockingQueue} with the given (fixed) capacity and the
    * specified access policy.
    *
    * @param capacity the capacity of this queue
-   * @param fair if <tt>true</tt> then queue accesses for threads blocked on insertion or removal,
-   *     are processed in FIFO order; if <tt>false</tt> the access order is unspecified.
-   * @throws IllegalArgumentException if <tt>capacity</tt> is less than 1
+   * @param fair if {@code true} then queue accesses for threads blocked on insertion or removal,
+   *     are processed in FIFO order; if {@code false} the access order is unspecified.
+   * @throws IllegalArgumentException if {@code capacity} is less than 1
    */
   public MonitorBasedArrayBlockingQueue(int capacity, boolean fair) {
     if (capacity <= 0) throw new IllegalArgumentException();
@@ -179,15 +179,15 @@ public boolean isSatisfied() {
   }
 
   /**
-   * Creates an <tt>MonitorBasedArrayBlockingQueue</tt> with the given (fixed) capacity, the
+   * Creates an {@code MonitorBasedArrayBlockingQueue} with the given (fixed) capacity, the
    * specified access policy and initially containing the elements of the given collection, added in
    * traversal order of the collection's iterator.
    *
    * @param capacity the capacity of this queue
-   * @param fair if <tt>true</tt> then queue accesses for threads blocked on insertion or removal,
-   *     are processed in FIFO order; if <tt>false</tt> the access order is unspecified.
+   * @param fair if {@code true} then queue accesses for threads blocked on insertion or removal,
+   *     are processed in FIFO order; if {@code false} the access order is unspecified.
    * @param c the collection of elements to initially contain
-   * @throws IllegalArgumentException if <tt>capacity</tt> is less than <tt>c.size()</tt>, or less
+   * @throws IllegalArgumentException if {@code capacity} is less than {@code c.size()}, or less
    *     than 1.
    * @throws NullPointerException if the specified collection or any of its elements are null
    */
@@ -205,11 +205,11 @@ private static <E> E[] newEArray(int capacity) {
 
   /**
    * Inserts the specified element at the tail of this queue if it is possible to do so immediately
-   * without exceeding the queue's capacity, returning <tt>true</tt> upon success and throwing an
-   * <tt>IllegalStateException</tt> if this queue is full.
+   * without exceeding the queue's capacity, returning {@code true} upon success and throwing an
+   * {@code IllegalStateException} if this queue is full.
    *
    * @param e the element to add
-   * @return <tt>true</tt> (as specified by {@link Collection#add})
+   * @return {@code true} (as specified by {@link Collection#add})
    * @throws IllegalStateException if this queue is full
    * @throws NullPointerException if the specified element is null
    */
@@ -220,7 +220,7 @@ public boolean add(E e) {
 
   /**
    * Inserts the specified element at the tail of this queue if it is possible to do so immediately
-   * without exceeding the queue's capacity, returning <tt>true</tt> upon success and <tt>false</tt>
+   * without exceeding the queue's capacity, returning {@code true} upon success and {@code false}
    * if this queue is full. This method is generally preferable to method {@link #add}, which can
    * fail to insert an element only by throwing an exception.
    *
@@ -361,11 +361,11 @@ public int size() {
   /**
    * Returns the number of additional elements that this queue can ideally (in the absence of memory
    * or resource constraints) accept without blocking. This is always equal to the initial capacity
-   * of this queue less the current <tt>size</tt> of this queue.
+   * of this queue less the current {@code size} of this queue.
    *
    * <p>Note that you <em>cannot</em> always tell if an attempt to insert an element will succeed by
-   * inspecting <tt>remainingCapacity</tt> because it may be the case that another thread is about
-   * to insert or remove an element.
+   * inspecting {@code remainingCapacity} because it may be the case that another thread is about to
+   * insert or remove an element.
    */
   @Override
   public int remainingCapacity() {
@@ -380,15 +380,15 @@ public int remainingCapacity() {
 
   /**
    * Removes a single instance of the specified element from this queue, if it is present. More
-   * formally, removes an element <tt>e</tt> such that <tt>o.equals(e)</tt>, if this queue contains
-   * one or more such elements. Returns <tt>true</tt> if this queue contained the specified element
+   * formally, removes an element {@code e} such that {@code o.equals(e)}, if this queue contains
+   * one or more such elements. Returns {@code true} if this queue contained the specified element
    * (or equivalently, if this queue changed as a result of the call).
    *
    * @param o element to be removed from this queue, if present
-   * @return <tt>true</tt> if this queue changed as a result of the call
+   * @return {@code true} if this queue changed as a result of the call
    */
   @Override
-  public boolean remove(@NullableDecl Object o) {
+  public boolean remove(@CheckForNull Object o) {
     if (o == null) return false;
     final E[] items = this.items;
     final Monitor monitor = this.monitor;
@@ -410,15 +410,15 @@ public boolean remove(@NullableDecl Object o) {
   }
 
   /**
-   * Returns <tt>true</tt> if this queue contains the specified element. More formally, returns
-   * <tt>true</tt> if and only if this queue contains at least one element <tt>e</tt> such that
-   * <tt>o.equals(e)</tt>.
+   * Returns {@code true} if this queue contains the specified element. More formally, returns
+   * {@code true} if and only if this queue contains at least one element {@code e} such that {@code
+   * o.equals(e)}.
    *
    * @param o object to be checked for containment in this queue
-   * @return <tt>true</tt> if this queue contains the specified element
+   * @return {@code true} if this queue contains the specified element
    */
   @Override
-  public boolean contains(@NullableDecl Object o) {
+  public boolean contains(@CheckForNull Object o) {
     if (o == null) return false;
     final E[] items = this.items;
     final Monitor monitor = this.monitor;
@@ -474,19 +474,19 @@ public Object[] toArray() {
    *
    * <p>If this queue fits in the specified array with room to spare (i.e., the array has more
    * elements than this queue), the element in the array immediately following the end of the queue
-   * is set to <tt>null</tt>.
+   * is set to {@code null}.
    *
    * <p>Like the {@link #toArray()} method, this method acts as bridge between array-based and
    * collection-based APIs. Further, this method allows precise control over the runtime type of the
    * output array, and may, under certain circumstances, be used to save allocation costs.
    *
-   * <p>Suppose <tt>x</tt> is a queue known to contain only strings. The following code can be used
-   * to dump the queue into a newly allocated array of <tt>String</tt>:
+   * <p>Suppose {@code x} is a queue known to contain only strings. The following code can be used
+   * to dump the queue into a newly allocated array of {@code String}:
    *
    * <pre>
    *     String[] y = x.toArray(new String[0]);</pre>
    *
-   * <p>Note that <tt>toArray(new Object[0])</tt> is identical in function to <tt>toArray()</tt>.
+   * <p>Note that {@code toArray(new Object[0])} is identical in function to {@code toArray()}.
    *
    * @param a the array into which the elements of the queue are to be stored, if it is big enough;
    *     otherwise, a new array of the same runtime type is allocated for this purpose
@@ -626,8 +626,8 @@ public int drainTo(Collection<? super E> c, int maxElements) {
   }
 
   /**
-   * Returns an iterator over the elements in this queue in proper sequence. The returned
-   * <tt>Iterator</tt> is a "weakly consistent" iterator that will never throw {@link
+   * Returns an iterator over the elements in this queue in proper sequence. The returned {@code
+   * Iterator} is a "weakly consistent" iterator that will never throw {@link
    * ConcurrentModificationException}, and guarantees to traverse elements as they existed upon
    * construction of the iterator, and may (but is not guaranteed to) reflect any modifications
    * subsequent to construction.
diff --git a/android/guava-tests/benchmark/com/google/common/util/concurrent/MonitorBasedPriorityBlockingQueue.java b/android/guava-tests/benchmark/com/google/common/util/concurrent/MonitorBasedPriorityBlockingQueue.java
index 715a9c815097..f61885be2630 100644
--- a/android/guava-tests/benchmark/com/google/common/util/concurrent/MonitorBasedPriorityBlockingQueue.java
+++ b/android/guava-tests/benchmark/com/google/common/util/concurrent/MonitorBasedPriorityBlockingQueue.java
@@ -30,28 +30,28 @@
 import java.util.SortedSet;
 import java.util.concurrent.BlockingQueue;
 import java.util.concurrent.TimeUnit;
-import org.checkerframework.checker.nullness.compatqual.NullableDecl;
+import javax.annotation.CheckForNull;
 
 /**
  * An unbounded {@linkplain BlockingQueue blocking queue} that uses the same ordering rules as class
  * {@link PriorityQueue} and supplies blocking retrieval operations. While this queue is logically
- * unbounded, attempted additions may fail due to resource exhaustion (causing
- * <tt>OutOfMemoryError</tt>). This class does not permit <tt>null</tt> elements. A priority queue
- * relying on {@linkplain Comparable natural ordering} also does not permit insertion of
- * non-comparable objects (doing so results in <tt>ClassCastException</tt>).
+ * unbounded, attempted additions may fail due to resource exhaustion (causing {@code
+ * OutOfMemoryError}). This class does not permit {@code null} elements. A priority queue relying on
+ * {@linkplain Comparable natural ordering} also does not permit insertion of non-comparable objects
+ * (doing so results in {@code ClassCastException}).
  *
  * <p>This class and its iterator implement all of the <em>optional</em> methods of the {@link
  * Collection} and {@link Iterator} interfaces. The Iterator provided in method {@link #iterator()}
  * is <em>not</em> guaranteed to traverse the elements of the MonitorBasedPriorityBlockingQueue in
- * any particular order. If you need ordered traversal, consider using
- * <tt>Arrays.sort(pq.toArray())</tt>. Also, method <tt>drainTo</tt> can be used to <em>remove</em>
- * some or all elements in priority order and place them in another collection.
+ * any particular order. If you need ordered traversal, consider using {@code
+ * Arrays.sort(pq.toArray())}. Also, method {@code drainTo} can be used to <em>remove</em> some or
+ * all elements in priority order and place them in another collection.
  *
  * <p>Operations on this class make no guarantees about the ordering of elements with equal
  * priority. If you need to enforce an ordering, you can define custom classes or comparators that
  * use a secondary key to break ties in primary priority values. For example, here is a class that
  * applies first-in-first-out tie-breaking to comparable elements. To use it, you would insert a
- * <tt>new FIFOEntry(anEntry)</tt> instead of a plain entry object.
+ * {@code new FIFOEntry(anEntry)} instead of a plain entry object.
  *
  * <pre>
  * class FIFOEntry&lt;E extends Comparable&lt;? super E&gt;&gt;
@@ -96,40 +96,40 @@ public boolean isSatisfied() {
       };
 
   /**
-   * Creates a <tt>MonitorBasedPriorityBlockingQueue</tt> with the default initial capacity (11)
-   * that orders its elements according to their {@linkplain Comparable natural ordering}.
+   * Creates a {@code MonitorBasedPriorityBlockingQueue} with the default initial capacity (11) that
+   * orders its elements according to their {@linkplain Comparable natural ordering}.
    */
   public MonitorBasedPriorityBlockingQueue() {
     q = new PriorityQueue<E>();
   }
 
   /**
-   * Creates a <tt>MonitorBasedPriorityBlockingQueue</tt> with the specified initial capacity that
+   * Creates a {@code MonitorBasedPriorityBlockingQueue} with the specified initial capacity that
    * orders its elements according to their {@linkplain Comparable natural ordering}.
    *
    * @param initialCapacity the initial capacity for this priority queue
-   * @throws IllegalArgumentException if <tt>initialCapacity</tt> is less than 1
+   * @throws IllegalArgumentException if {@code initialCapacity} is less than 1
    */
   public MonitorBasedPriorityBlockingQueue(int initialCapacity) {
     q = new PriorityQueue<E>(initialCapacity, null);
   }
 
   /**
-   * Creates a <tt>MonitorBasedPriorityBlockingQueue</tt> with the specified initial capacity that
+   * Creates a {@code MonitorBasedPriorityBlockingQueue} with the specified initial capacity that
    * orders its elements according to the specified comparator.
    *
    * @param initialCapacity the initial capacity for this priority queue
    * @param comparator the comparator that will be used to order this priority queue. If {@code
    *     null}, the {@linkplain Comparable natural ordering} of the elements will be used.
-   * @throws IllegalArgumentException if <tt>initialCapacity</tt> is less than 1
+   * @throws IllegalArgumentException if {@code initialCapacity} is less than 1
    */
   public MonitorBasedPriorityBlockingQueue(
-      int initialCapacity, @NullableDecl Comparator<? super E> comparator) {
+      int initialCapacity, @CheckForNull Comparator<? super E> comparator) {
     q = new PriorityQueue<E>(initialCapacity, comparator);
   }
 
   /**
-   * Creates a <tt>MonitorBasedPriorityBlockingQueue</tt> containing the elements in the specified
+   * Creates a {@code MonitorBasedPriorityBlockingQueue} containing the elements in the specified
    * collection. If the specified collection is a {@link SortedSet} or a {@link PriorityQueue}, this
    * priority queue will be ordered according to the same ordering. Otherwise, this priority queue
    * will be ordered according to the {@linkplain Comparable natural ordering} of its elements.
@@ -147,7 +147,7 @@ public MonitorBasedPriorityBlockingQueue(Collection<? extends E> c) {
    * Inserts the specified element into this priority queue.
    *
    * @param e the element to add
-   * @return <tt>true</tt> (as specified by {@link Collection#add})
+   * @return {@code true} (as specified by {@link Collection#add})
    * @throws ClassCastException if the specified element cannot be compared with elements currently
    *     in the priority queue according to the priority queue's ordering
    * @throws NullPointerException if the specified element is null
@@ -161,7 +161,7 @@ public boolean add(E e) {
    * Inserts the specified element into this priority queue.
    *
    * @param e the element to add
-   * @return <tt>true</tt> (as specified by {@link Queue#offer})
+   * @return {@code true} (as specified by {@link Queue#offer})
    * @throws ClassCastException if the specified element cannot be compared with elements currently
    *     in the priority queue according to the priority queue's ordering
    * @throws NullPointerException if the specified element is null
@@ -188,7 +188,7 @@ public boolean offer(E e) {
    * @param e the element to add
    * @param timeout This parameter is ignored as the method never blocks
    * @param unit This parameter is ignored as the method never blocks
-   * @return <tt>true</tt>
+   * @return {@code true}
    * @throws ClassCastException if the specified element cannot be compared with elements currently
    *     in the priority queue according to the priority queue's ordering
    * @throws NullPointerException if the specified element is null
@@ -261,10 +261,10 @@ public E peek() {
   }
 
   /**
-   * Returns the comparator used to order the elements in this queue, or <tt>null</tt> if this queue
+   * Returns the comparator used to order the elements in this queue, or {@code null} if this queue
    * uses the {@linkplain Comparable natural ordering} of its elements.
    *
-   * @return the comparator used to order the elements in this queue, or <tt>null</tt> if this queue
+   * @return the comparator used to order the elements in this queue, or {@code null} if this queue
    *     uses the natural ordering of its elements
    */
   public Comparator<? super E> comparator() {
@@ -283,10 +283,10 @@ public int size() {
   }
 
   /**
-   * Always returns <tt>Integer.MAX_VALUE</tt> because a <tt>MonitorBasedPriorityBlockingQueue</tt>
-   * is not capacity constrained.
+   * Always returns {@code Integer.MAX_VALUE} because a {@code MonitorBasedPriorityBlockingQueue} is
+   * not capacity constrained.
    *
-   * @return <tt>Integer.MAX_VALUE</tt>
+   * @return {@code Integer.MAX_VALUE}
    */
   @Override
   public int remainingCapacity() {
@@ -300,10 +300,10 @@ public int remainingCapacity() {
    * specified element (or equivalently, if this queue changed as a result of the call).
    *
    * @param o element to be removed from this queue, if present
-   * @return <tt>true</tt> if this queue changed as a result of the call
+   * @return {@code true} if this queue changed as a result of the call
    */
   @Override
-  public boolean remove(@NullableDecl Object o) {
+  public boolean remove(@CheckForNull Object o) {
     final Monitor monitor = this.monitor;
     monitor.enter();
     try {
@@ -319,10 +319,10 @@ public boolean remove(@NullableDecl Object o) {
    * o.equals(e)}.
    *
    * @param o object to be checked for containment in this queue
-   * @return <tt>true</tt> if this queue contains the specified element
+   * @return {@code true} if this queue contains the specified element
    */
   @Override
-  public boolean contains(@NullableDecl Object o) {
+  public boolean contains(@CheckForNull Object o) {
     final Monitor monitor = this.monitor;
     monitor.enter();
     try {
@@ -363,19 +363,19 @@ public Object[] toArray() {
    *
    * <p>If this queue fits in the specified array with room to spare (i.e., the array has more
    * elements than this queue), the element in the array immediately following the end of the queue
-   * is set to <tt>null</tt>.
+   * is set to {@code null}.
    *
    * <p>Like the {@link #toArray()} method, this method acts as bridge between array-based and
    * collection-based APIs. Further, this method allows precise control over the runtime type of the
    * output array, and may, under certain circumstances, be used to save allocation costs.
    *
-   * <p>Suppose <tt>x</tt> is a queue known to contain only strings. The following code can be used
-   * to dump the queue into a newly allocated array of <tt>String</tt>:
+   * <p>Suppose {@code x} is a queue known to contain only strings. The following code can be used
+   * to dump the queue into a newly allocated array of {@code String}:
    *
    * <pre>
    *     String[] y = x.toArray(new String[0]);</pre>
    *
-   * <p>Note that <tt>toArray(new Object[0])</tt> is identical in function to <tt>toArray()</tt>.
+   * <p>Note that {@code toArray(new Object[0])} is identical in function to {@code toArray()}.
    *
    * @param a the array into which the elements of the queue are to be stored, if it is big enough;
    *     otherwise, a new array of the same runtime type is allocated for this purpose
@@ -474,7 +474,7 @@ public void clear() {
 
   /**
    * Returns an iterator over the elements in this queue. The iterator does not return the elements
-   * in any particular order. The returned <tt>Iterator</tt> is a "weakly consistent" iterator that
+   * in any particular order. The returned {@code Iterator} is a "weakly consistent" iterator that
    * will never throw {@link ConcurrentModificationException}, and guarantees to traverse elements
    * as they existed upon construction of the iterator, and may (but is not guaranteed to) reflect
    * any modifications subsequent to construction.
diff --git a/android/guava-tests/pom.xml b/android/guava-tests/pom.xml
index 5f56f4b3a0bd..13a8d8dc11f7 100644
--- a/android/guava-tests/pom.xml
+++ b/android/guava-tests/pom.xml
@@ -5,7 +5,7 @@
   <parent>
     <groupId>com.google.guava</groupId>
     <artifactId>guava-parent</artifactId>
-    <version>HEAD-android-SNAPSHOT</version>
+    <version>31.1-android</version>
   </parent>
   <artifactId>guava-tests</artifactId>
   <name>Guava Unit Tests</name>
@@ -25,10 +25,6 @@
       <groupId>com.google.code.findbugs</groupId>
       <artifactId>jsr305</artifactId>
     </dependency>
-    <dependency>
-      <groupId>org.checkerframework</groupId>
-      <artifactId>checker-compat-qual</artifactId>
-    </dependency>
     <dependency>
       <groupId>com.google.errorprone</groupId>
       <artifactId>error_prone_annotations</artifactId>
@@ -102,6 +98,9 @@
       <plugin>
         <groupId>org.codehaus.mojo</groupId>
         <artifactId>animal-sniffer-maven-plugin</artifactId>
+        <configuration>
+          <checkTestClasses>false</checkTestClasses> <!-- TODO(cpovirk): Consider checking them. -->
+        </configuration>
       </plugin>
       <plugin>
         <groupId>org.codehaus.mojo</groupId>
diff --git a/android/guava-tests/test/com/google/common/base/AbstractIteratorTest.java b/android/guava-tests/test/com/google/common/base/AbstractIteratorTest.java
index da732bf54946..ddb7d709739a 100644
--- a/android/guava-tests/test/com/google/common/base/AbstractIteratorTest.java
+++ b/android/guava-tests/test/com/google/common/base/AbstractIteratorTest.java
@@ -205,7 +205,7 @@ protected Integer computeNext() {
   // hasNext/next), but we'll cop out for now, knowing that
   // next() both start by invoking hasNext() anyway.
 
-  /** Throws a undeclared checked exception. */
+  /** Throws an undeclared checked exception. */
   private static void sneakyThrow(Throwable t) {
     class SneakyThrower<T extends Throwable> {
       @SuppressWarnings("unchecked") // intentionally unsafe for test
diff --git a/android/guava-tests/test/com/google/common/base/AsciiTest.java b/android/guava-tests/test/com/google/common/base/AsciiTest.java
index d3a1f8f6597e..9e6b0e41ab86 100644
--- a/android/guava-tests/test/com/google/common/base/AsciiTest.java
+++ b/android/guava-tests/test/com/google/common/base/AsciiTest.java
@@ -54,8 +54,8 @@ public void testToUpperCase() {
   public void testCharsIgnored() {
     for (char c : IGNORED.toCharArray()) {
       String str = String.valueOf(c);
-      assertTrue(str, c == Ascii.toLowerCase(c));
-      assertTrue(str, c == Ascii.toUpperCase(c));
+      assertEquals(str, c, Ascii.toLowerCase(c));
+      assertEquals(str, c, Ascii.toUpperCase(c));
       assertFalse(str, Ascii.isLowerCase(c));
       assertFalse(str, Ascii.isUpperCase(c));
     }
@@ -98,27 +98,26 @@ public void testTruncate() {
   }
 
   public void testTruncateIllegalArguments() {
-    String truncated = null;
     try {
-      truncated = Ascii.truncate("foobar", 2, "...");
+      Ascii.truncate("foobar", 2, "...");
       fail();
     } catch (IllegalArgumentException expected) {
     }
 
     try {
-      truncated = Ascii.truncate("foobar", 8, "1234567890");
+      Ascii.truncate("foobar", 8, "1234567890");
       fail();
     } catch (IllegalArgumentException expected) {
     }
 
     try {
-      truncated = Ascii.truncate("foobar", -1, "...");
+      Ascii.truncate("foobar", -1, "...");
       fail();
     } catch (IllegalArgumentException expected) {
     }
 
     try {
-      truncated = Ascii.truncate("foobar", -1, "");
+      Ascii.truncate("foobar", -1, "");
       fail();
     } catch (IllegalArgumentException expected) {
     }
diff --git a/android/guava-tests/test/com/google/common/base/CharMatcherTest.java b/android/guava-tests/test/com/google/common/base/CharMatcherTest.java
index 5412882c5641..49bdbbaffe25 100644
--- a/android/guava-tests/test/com/google/common/base/CharMatcherTest.java
+++ b/android/guava-tests/test/com/google/common/base/CharMatcherTest.java
@@ -386,7 +386,7 @@ private void reallyTestOneCharNoMatch(CharMatcher matcher, String s) {
     assertSame(s, matcher.replaceFrom(s, 'z'));
     assertSame(s, matcher.replaceFrom(s, "ZZ"));
     assertSame(s, matcher.trimFrom(s));
-    assertSame(0, matcher.countIn(s));
+    assertEquals(0, matcher.countIn(s));
   }
 
   private void reallyTestMatchThenNoMatch(CharMatcher matcher, String s) {
diff --git a/android/guava-tests/test/com/google/common/base/OptionalTest.java b/android/guava-tests/test/com/google/common/base/OptionalTest.java
index 1f542f02411a..74178e2e52ba 100644
--- a/android/guava-tests/test/com/google/common/base/OptionalTest.java
+++ b/android/guava-tests/test/com/google/common/base/OptionalTest.java
@@ -68,6 +68,7 @@ public void testIsPresent_no() {
     assertFalse(Optional.absent().isPresent());
   }
 
+  @SuppressWarnings("OptionalOfRedundantMethod") // Unit tests for Optional
   public void testIsPresent_yes() {
     assertTrue(Optional.of("training").isPresent());
   }
@@ -85,6 +86,7 @@ public void testGet_present() {
     assertEquals("training", Optional.of("training").get());
   }
 
+  @SuppressWarnings("OptionalOfRedundantMethod") // Unit tests for Optional
   public void testOr_T_present() {
     assertEquals("a", Optional.of("a").or("default"));
   }
@@ -93,6 +95,7 @@ public void testOr_T_absent() {
     assertEquals("default", Optional.absent().or("default"));
   }
 
+  @SuppressWarnings("OptionalOfRedundantMethod") // Unit tests for Optional
   public void testOr_supplier_present() {
     assertEquals("a", Optional.of("a").or(Suppliers.ofInstance("fallback")));
   }
@@ -111,11 +114,13 @@ public void testOr_nullSupplier_absent() {
     }
   }
 
+  @SuppressWarnings("OptionalOfRedundantMethod") // Unit tests for Optional
   public void testOr_nullSupplier_present() {
     Supplier<String> nullSupplier = Suppliers.ofInstance(null);
     assertEquals("a", Optional.of("a").or(nullSupplier));
   }
 
+  @SuppressWarnings("OptionalOfRedundantMethod") // Unit tests for Optional
   public void testOr_Optional_present() {
     assertEquals(Optional.of("a"), Optional.of("a").or(Optional.of("fallback")));
   }
@@ -124,6 +129,7 @@ public void testOr_Optional_absent() {
     assertEquals(Optional.of("fallback"), Optional.absent().or(Optional.of("fallback")));
   }
 
+  @SuppressWarnings("OptionalOfRedundantMethod") // Unit tests for Optional
   public void testOrNull_present() {
     assertEquals("a", Optional.of("a").orNull());
   }
diff --git a/android/guava-tests/test/com/google/common/base/PreconditionsTest.java b/android/guava-tests/test/com/google/common/base/PreconditionsTest.java
index 072649f99da1..1add44d32386 100644
--- a/android/guava-tests/test/com/google/common/base/PreconditionsTest.java
+++ b/android/guava-tests/test/com/google/common/base/PreconditionsTest.java
@@ -24,7 +24,6 @@
 import com.google.common.collect.ImmutableSet;
 import com.google.common.collect.Lists;
 import com.google.common.testing.ArbitraryInstances;
-import com.google.common.testing.NullPointerTester;
 import java.lang.reflect.InvocationTargetException;
 import java.lang.reflect.Method;
 import java.util.ArrayList;
@@ -539,8 +538,22 @@ public void overloadSelection() {
 
   @GwtIncompatible // NullPointerTester
   public void testNullPointers() {
-    NullPointerTester tester = new NullPointerTester();
-    tester.testAllPublicStaticMethods(Preconditions.class);
+    /*
+     * Don't bother testing: Preconditions defines a bunch of methods that accept a template (or
+     * even entire message) that simultaneously:
+     *
+     * - _shouldn't_ be null, so we don't annotate it with @Nullable
+     *
+     * - _can_ be null without causing a runtime failure (because we don't want the interesting
+     *   details of precondition failure to be hidden by an exception we throw about an unexpectedly
+     *   null _failure message_)
+     *
+     * That combination upsets NullPointerTester, which wants any call that passes null for a
+     * non-@Nullable parameter to trigger a NullPointerException.
+     *
+     * (We still define this empty method to keep PackageSanityTests from generating its own
+     * automated nullness tests, which would fail.)
+     */
   }
 
   private static final Object IGNORE_ME =
diff --git a/android/guava-tests/test/com/google/common/base/ToStringHelperTest.java b/android/guava-tests/test/com/google/common/base/ToStringHelperTest.java
index 3f1ef0f9e829..db15f2ef811c 100644
--- a/android/guava-tests/test/com/google/common/base/ToStringHelperTest.java
+++ b/android/guava-tests/test/com/google/common/base/ToStringHelperTest.java
@@ -116,15 +116,15 @@ class LocalInnerNestedClass {}
   @GwtIncompatible // Class names are obfuscated in GWT
   public void testToStringHelper_moreThanNineAnonymousClasses() {
     // The nth anonymous class has a name ending like "Outer.$n"
-    Object o1 = new Object() {};
-    Object o2 = new Object() {};
-    Object o3 = new Object() {};
-    Object o4 = new Object() {};
-    Object o5 = new Object() {};
-    Object o6 = new Object() {};
-    Object o7 = new Object() {};
-    Object o8 = new Object() {};
-    Object o9 = new Object() {};
+    Object unused1 = new Object() {};
+    Object unused2 = new Object() {};
+    Object unused3 = new Object() {};
+    Object unused4 = new Object() {};
+    Object unused5 = new Object() {};
+    Object unused6 = new Object() {};
+    Object unused7 = new Object() {};
+    Object unused8 = new Object() {};
+    Object unused9 = new Object() {};
     Object o10 = new Object() {};
     String toTest = MoreObjects.toStringHelper(o10).toString();
     assertEquals("{}", toTest);
@@ -132,15 +132,15 @@ public void testToStringHelper_moreThanNineAnonymousClasses() {
 
   public void testToStringHelperLenient_moreThanNineAnonymousClasses() {
     // The nth anonymous class has a name ending like "Outer.$n"
-    Object o1 = new Object() {};
-    Object o2 = new Object() {};
-    Object o3 = new Object() {};
-    Object o4 = new Object() {};
-    Object o5 = new Object() {};
-    Object o6 = new Object() {};
-    Object o7 = new Object() {};
-    Object o8 = new Object() {};
-    Object o9 = new Object() {};
+    Object unused1 = new Object() {};
+    Object unused2 = new Object() {};
+    Object unused3 = new Object() {};
+    Object unused4 = new Object() {};
+    Object unused5 = new Object() {};
+    Object unused6 = new Object() {};
+    Object unused7 = new Object() {};
+    Object unused8 = new Object() {};
+    Object unused9 = new Object() {};
     Object o10 = new Object() {};
     String toTest = MoreObjects.toStringHelper(o10).toString();
     assertTrue(toTest, toTest.matches(".*\\{\\}"));
@@ -357,7 +357,7 @@ public void testToStringOmitNullValues_manyFieldsLastNull() {
   }
 
   @GwtIncompatible // Class names are obfuscated in GWT
-  public void testToStringOmitNullValues_oneValue() {
+  public void testToStringOmitEmptyValues_oneValue() {
     String toTest =
         MoreObjects.toStringHelper(new TestClass()).omitNullValues().addValue(null).toString();
     assertEquals("TestClass{}", toTest);
diff --git a/android/guava-tests/test/com/google/common/base/VerifyTest.java b/android/guava-tests/test/com/google/common/base/VerifyTest.java
index 03d2c2ff4a28..37c6efc1a990 100644
--- a/android/guava-tests/test/com/google/common/base/VerifyTest.java
+++ b/android/guava-tests/test/com/google/common/base/VerifyTest.java
@@ -19,11 +19,12 @@
 import static com.google.common.truth.Truth.assertThat;
 
 import com.google.common.annotations.GwtCompatible;
+import com.google.common.annotations.GwtIncompatible;
 import junit.framework.AssertionFailedError;
 import junit.framework.TestCase;
 
 /** Unit test for {@link com.google.common.base.Verify}. */
-@GwtCompatible
+@GwtCompatible(emulated = true)
 public class VerifyTest extends TestCase {
   public void testVerify_simple_success() {
     verify(true);
@@ -92,6 +93,11 @@ public void testVerifyNotNull_simpleMessage_failure() {
     }
   }
 
+  @GwtIncompatible // NullPointerTester
+  public void testNullPointers() {
+    // Don't bother testing: Verify is like Preconditions. See the discussion on that class.
+  }
+
   private static final Object IGNORE_ME =
       new Object() {
         @Override
diff --git a/android/guava-tests/test/com/google/common/cache/CacheBuilderFactory.java b/android/guava-tests/test/com/google/common/cache/CacheBuilderFactory.java
index 04b6f1ef5d6a..948b4b560467 100644
--- a/android/guava-tests/test/com/google/common/cache/CacheBuilderFactory.java
+++ b/android/guava-tests/test/com/google/common/cache/CacheBuilderFactory.java
@@ -26,7 +26,7 @@
 import java.util.List;
 import java.util.Set;
 import java.util.concurrent.TimeUnit;
-import org.checkerframework.checker.nullness.compatqual.NullableDecl;
+import javax.annotation.CheckForNull;
 
 /**
  * Helper class for creating {@link CacheBuilder} instances with all combinations of several sets of
@@ -120,7 +120,7 @@ public CacheBuilder<Object, Object> apply(List<Object> combination) {
   private static final Function<Object, Optional<?>> NULLABLE_TO_OPTIONAL =
       new Function<Object, Optional<?>>() {
         @Override
-        public Optional<?> apply(@NullableDecl Object obj) {
+        public Optional<?> apply(@CheckForNull Object obj) {
           return Optional.fromNullable(obj);
         }
       };
diff --git a/android/guava-tests/test/com/google/common/cache/CacheTesting.java b/android/guava-tests/test/com/google/common/cache/CacheTesting.java
index 255a89480ff2..4c58ed50272c 100644
--- a/android/guava-tests/test/com/google/common/cache/CacheTesting.java
+++ b/android/guava-tests/test/com/google/common/cache/CacheTesting.java
@@ -44,7 +44,7 @@
 import java.util.concurrent.ConcurrentMap;
 import java.util.concurrent.TimeUnit;
 import java.util.concurrent.atomic.AtomicReferenceArray;
-import org.checkerframework.checker.nullness.compatqual.NullableDecl;
+import javax.annotation.CheckForNull;
 
 /**
  * A collection of utilities for {@link Cache} testing.
@@ -367,7 +367,7 @@ static void processPendingNotifications(Cache<?, ?> cache) {
   }
 
   interface Receiver<T> {
-    void accept(@NullableDecl T object);
+    void accept(@CheckForNull T object);
   }
 
   /**
diff --git a/android/guava-tests/test/com/google/common/cache/LocalCacheTest.java b/android/guava-tests/test/com/google/common/cache/LocalCacheTest.java
index 3c4529cafc0f..b8ec7dfe6882 100644
--- a/android/guava-tests/test/com/google/common/cache/LocalCacheTest.java
+++ b/android/guava-tests/test/com/google/common/cache/LocalCacheTest.java
@@ -232,7 +232,7 @@ public void tearDown() throws Exception {
 
   private Throwable popLoggedThrowable() {
     List<LogRecord> logRecords = logHandler.getStoredLogRecords();
-    assertSame(1, logRecords.size());
+    assertEquals(1, logRecords.size());
     LogRecord logRecord = logRecords.get(0);
     logHandler.clear();
     return logRecord.getThrown();
diff --git a/android/guava-tests/test/com/google/common/cache/TestingCacheLoaders.java b/android/guava-tests/test/com/google/common/cache/TestingCacheLoaders.java
index 8507e68f2eb9..6cc02602126e 100644
--- a/android/guava-tests/test/com/google/common/cache/TestingCacheLoaders.java
+++ b/android/guava-tests/test/com/google/common/cache/TestingCacheLoaders.java
@@ -23,7 +23,7 @@
 import com.google.common.util.concurrent.ListenableFuture;
 import java.util.Map;
 import java.util.concurrent.atomic.AtomicInteger;
-import org.checkerframework.checker.nullness.compatqual.NullableDecl;
+import javax.annotation.CheckForNull;
 
 /**
  * Utility {@link CacheLoader} implementations intended for use in testing.
@@ -57,7 +57,7 @@ public Map<K, V> loadAll(Iterable<? extends K> keys) throws Exception {
   }
 
   /** Returns a {@link CacheLoader} that returns the given {@code constant} for every request. */
-  static <K, V> ConstantLoader<K, V> constantLoader(@NullableDecl V constant) {
+  static <K, V> ConstantLoader<K, V> constantLoader(@CheckForNull V constant) {
     return new ConstantLoader<>(constant);
   }
 
diff --git a/android/guava-tests/test/com/google/common/collect/AbstractIteratorTest.java b/android/guava-tests/test/com/google/common/collect/AbstractIteratorTest.java
index 35922105f196..a76907cda7c7 100644
--- a/android/guava-tests/test/com/google/common/collect/AbstractIteratorTest.java
+++ b/android/guava-tests/test/com/google/common/collect/AbstractIteratorTest.java
@@ -250,6 +250,7 @@ public Integer computeNext() {
     }
   }
 
+  @SuppressWarnings("DoNotCall")
   public void testCantRemove() {
     Iterator<Integer> iter =
         new AbstractIterator<Integer>() {
diff --git a/android/guava-tests/test/com/google/common/collect/AbstractMapEntryTest.java b/android/guava-tests/test/com/google/common/collect/AbstractMapEntryTest.java
index 11c66a702375..63c17dedaeca 100644
--- a/android/guava-tests/test/com/google/common/collect/AbstractMapEntryTest.java
+++ b/android/guava-tests/test/com/google/common/collect/AbstractMapEntryTest.java
@@ -61,7 +61,8 @@ public void testToStringNull() {
 
   public void testEquals() {
     Entry<String, Integer> foo1 = entry("foo", 1);
-    assertEquals(foo1, foo1);
+    // Explicitly call `equals`; `assertEquals` might return fast
+    assertTrue(foo1.equals(foo1));
     assertEquals(control("foo", 1), foo1);
     assertEquals(control("bar", 2), entry("bar", 2));
     assertFalse(control("foo", 1).equals(entry("foo", 2)));
diff --git a/android/guava-tests/test/com/google/common/collect/DiscreteDomainTest.java b/android/guava-tests/test/com/google/common/collect/DiscreteDomainTest.java
index 5de3f8df2be1..b9e15fd9ca65 100644
--- a/android/guava-tests/test/com/google/common/collect/DiscreteDomainTest.java
+++ b/android/guava-tests/test/com/google/common/collect/DiscreteDomainTest.java
@@ -87,4 +87,48 @@ public void testBigIntegersOffsetExceptions() {
     } catch (IllegalArgumentException expected) {
     }
   }
+
+  public void testCustomOffsetExceptions() {
+    try {
+      new MyIntegerDomain().offset(0, -1);
+      fail();
+    } catch (IllegalArgumentException expected) {
+    }
+    try {
+      new MyIntegerDomain().offset(Integer.MAX_VALUE, 1);
+      fail();
+    } catch (IllegalArgumentException expected) {
+    }
+  }
+
+  private static final class MyIntegerDomain extends DiscreteDomain<Integer> {
+    static final DiscreteDomain<Integer> DELEGATE = DiscreteDomain.integers();
+
+    @Override
+    public Integer next(Integer value) {
+      return DELEGATE.next(value);
+    }
+
+    @Override
+    public Integer previous(Integer value) {
+      return DELEGATE.previous(value);
+    }
+
+    // Do *not* override offset() to delegate: We want to test the default implementation.
+
+    @Override
+    public long distance(Integer start, Integer end) {
+      return DELEGATE.distance(start, end);
+    }
+
+    @Override
+    public Integer minValue() {
+      return DELEGATE.minValue();
+    }
+
+    @Override
+    public Integer maxValue() {
+      return DELEGATE.maxValue();
+    }
+  }
 }
diff --git a/android/guava-tests/test/com/google/common/collect/FluentIterableTest.java b/android/guava-tests/test/com/google/common/collect/FluentIterableTest.java
index e623f31d2f36..b8427b1c8140 100644
--- a/android/guava-tests/test/com/google/common/collect/FluentIterableTest.java
+++ b/android/guava-tests/test/com/google/common/collect/FluentIterableTest.java
@@ -38,9 +38,9 @@
 import java.util.Set;
 import java.util.SortedSet;
 import java.util.concurrent.TimeUnit;
+import javax.annotation.CheckForNull;
 import junit.framework.AssertionFailedError;
 import junit.framework.TestCase;
-import org.checkerframework.checker.nullness.compatqual.NullableDecl;
 
 /**
  * Unit test for {@link FluentIterable}.
@@ -850,7 +850,7 @@ public void testUniqueIndex_nullValue() {
               .uniqueIndex(
                   new Function<Integer, Object>() {
                     @Override
-                    public Object apply(@NullableDecl Integer input) {
+                    public Object apply(@CheckForNull Integer input) {
                       return String.valueOf(input);
                     }
                   });
diff --git a/android/guava-tests/test/com/google/common/collect/ForwardingMapTest.java b/android/guava-tests/test/com/google/common/collect/ForwardingMapTest.java
index cc5d73967607..cf2ed0d3b5f1 100644
--- a/android/guava-tests/test/com/google/common/collect/ForwardingMapTest.java
+++ b/android/guava-tests/test/com/google/common/collect/ForwardingMapTest.java
@@ -170,7 +170,7 @@ protected Map<String, String> create(Entry<String, String>[] entries) {
                     for (Entry<String, String> entry : entries) {
                       builder.put(entry.getKey(), entry.getValue());
                     }
-                    return new StandardImplForwardingMap<>(builder.build());
+                    return new StandardImplForwardingMap<>(builder.buildOrThrow());
                   }
                 })
             .named("ForwardingMap[ImmutableMap] with standard implementations")
diff --git a/android/guava-tests/test/com/google/common/collect/ForwardingSortedMultisetTest.java b/android/guava-tests/test/com/google/common/collect/ForwardingSortedMultisetTest.java
index d0673f1d0d7c..2b77cd5e4b74 100644
--- a/android/guava-tests/test/com/google/common/collect/ForwardingSortedMultisetTest.java
+++ b/android/guava-tests/test/com/google/common/collect/ForwardingSortedMultisetTest.java
@@ -27,10 +27,10 @@
 import java.util.Iterator;
 import java.util.List;
 import java.util.NavigableSet;
+import javax.annotation.CheckForNull;
 import junit.framework.Test;
 import junit.framework.TestCase;
 import junit.framework.TestSuite;
-import org.checkerframework.checker.nullness.compatqual.NullableDecl;
 
 /**
  * Tests for {@link ForwardingSortedMultiset}.
@@ -93,12 +93,12 @@ public SortedMultiset<E> subMultiset(
     }
 
     @Override
-    public int count(@NullableDecl Object element) {
+    public int count(@CheckForNull Object element) {
       return standardCount(element);
     }
 
     @Override
-    public boolean equals(@NullableDecl Object object) {
+    public boolean equals(@CheckForNull Object object) {
       return standardEquals(object);
     }
 
@@ -123,7 +123,7 @@ public void clear() {
     }
 
     @Override
-    public boolean contains(@NullableDecl Object object) {
+    public boolean contains(@CheckForNull Object object) {
       return standardContains(object);
     }
 
@@ -143,7 +143,7 @@ public Iterator<E> iterator() {
     }
 
     @Override
-    public boolean remove(@NullableDecl Object object) {
+    public boolean remove(@CheckForNull Object object) {
       return standardRemove(object);
     }
 
diff --git a/android/guava-tests/test/com/google/common/collect/ImmutableBiMapTest.java b/android/guava-tests/test/com/google/common/collect/ImmutableBiMapTest.java
index b4f99725702a..e01b094fed93 100644
--- a/android/guava-tests/test/com/google/common/collect/ImmutableBiMapTest.java
+++ b/android/guava-tests/test/com/google/common/collect/ImmutableBiMapTest.java
@@ -32,6 +32,7 @@
 import com.google.common.collect.testing.google.BiMapInverseTester;
 import com.google.common.collect.testing.google.BiMapTestSuiteBuilder;
 import com.google.common.testing.SerializableTester;
+import java.util.AbstractMap;
 import java.util.Collections;
 import java.util.LinkedHashMap;
 import java.util.Map;
@@ -322,6 +323,7 @@ public void testBuilderPutNullValueViaPutAll() {
       }
     }
 
+    @SuppressWarnings("AlwaysThrows")
     public void testPuttingTheSameKeyTwiceThrowsOnBuild() {
       Builder<String, Integer> builder =
           new Builder<String, Integer>()
@@ -395,6 +397,136 @@ public void testOf() {
           "four",
           5,
           "five");
+      assertMapEquals(
+          ImmutableBiMap.of(
+              "one", 1,
+              "two", 2,
+              "three", 3,
+              "four", 4,
+              "five", 5,
+              "six", 6),
+          "one",
+          1,
+          "two",
+          2,
+          "three",
+          3,
+          "four",
+          4,
+          "five",
+          5,
+          "six",
+          6);
+      assertMapEquals(
+          ImmutableBiMap.of(
+              "one", 1,
+              "two", 2,
+              "three", 3,
+              "four", 4,
+              "five", 5,
+              "six", 6,
+              "seven", 7),
+          "one",
+          1,
+          "two",
+          2,
+          "three",
+          3,
+          "four",
+          4,
+          "five",
+          5,
+          "six",
+          6,
+          "seven",
+          7);
+      assertMapEquals(
+          ImmutableBiMap.of(
+              "one", 1,
+              "two", 2,
+              "three", 3,
+              "four", 4,
+              "five", 5,
+              "six", 6,
+              "seven", 7,
+              "eight", 8),
+          "one",
+          1,
+          "two",
+          2,
+          "three",
+          3,
+          "four",
+          4,
+          "five",
+          5,
+          "six",
+          6,
+          "seven",
+          7,
+          "eight",
+          8);
+      assertMapEquals(
+          ImmutableBiMap.of(
+              "one", 1,
+              "two", 2,
+              "three", 3,
+              "four", 4,
+              "five", 5,
+              "six", 6,
+              "seven", 7,
+              "eight", 8,
+              "nine", 9),
+          "one",
+          1,
+          "two",
+          2,
+          "three",
+          3,
+          "four",
+          4,
+          "five",
+          5,
+          "six",
+          6,
+          "seven",
+          7,
+          "eight",
+          8,
+          "nine",
+          9);
+      assertMapEquals(
+          ImmutableBiMap.of(
+              "one", 1,
+              "two", 2,
+              "three", 3,
+              "four", 4,
+              "five", 5,
+              "six", 6,
+              "seven", 7,
+              "eight", 8,
+              "nine", 9,
+              "ten", 10),
+          "one",
+          1,
+          "two",
+          2,
+          "three",
+          3,
+          "four",
+          4,
+          "five",
+          5,
+          "six",
+          6,
+          "seven",
+          7,
+          "eight",
+          8,
+          "nine",
+          9,
+          "ten",
+          10);
     }
 
     public void testOfNullKey() {
@@ -425,6 +557,7 @@ public void testOfNullValue() {
       }
     }
 
+    @SuppressWarnings("AlwaysThrows")
     public void testOfWithDuplicateKey() {
       try {
         ImmutableBiMap.of("one", 1, "one", 1);
@@ -434,6 +567,30 @@ public void testOfWithDuplicateKey() {
       }
     }
 
+    public void testOfEntries() {
+      assertMapEquals(
+          ImmutableBiMap.ofEntries(entry("one", 1), entry("two", 2)), "one", 1, "two", 2);
+    }
+
+    public void testOfEntriesNull() {
+      Entry<Integer, Integer> nullKey = entry(null, 23);
+      try {
+        ImmutableBiMap.ofEntries(nullKey);
+        fail();
+      } catch (NullPointerException expected) {
+      }
+      Entry<Integer, Integer> nullValue = entry(23, null);
+      try {
+        ImmutableBiMap.ofEntries(nullValue);
+        fail();
+      } catch (NullPointerException expected) {
+      }
+    }
+
+    private static <T> Entry<T, T> entry(T key, T value) {
+      return new AbstractMap.SimpleImmutableEntry<>(key, value);
+    }
+
     public void testCopyOfEmptyMap() {
       ImmutableBiMap<String, Integer> copy =
           ImmutableBiMap.copyOf(Collections.<String, Integer>emptyMap());
@@ -485,7 +642,7 @@ public void testFromImmutableMap() {
                   .put("three", 3)
                   .put("four", 4)
                   .put("five", 5)
-                  .build());
+                  .buildOrThrow());
       assertMapEquals(bimap, "one", 1, "two", 2, "three", 3, "four", 4, "five", 5);
       assertMapEquals(bimap.inverse(), 1, "one", 2, "two", 3, "three", 4, "four", 5, "five");
     }
@@ -497,13 +654,14 @@ public void testDuplicateValues() {
               .put("two", 2)
               .put("uno", 1)
               .put("dos", 2)
-              .build();
+              .buildOrThrow();
 
       try {
         ImmutableBiMap.copyOf(map);
         fail();
       } catch (IllegalArgumentException expected) {
-        assertThat(expected.getMessage()).contains("1");
+        assertThat(expected.getMessage()).containsMatch("1|2");
+        // We don't specify which of the two dups should be reported.
       }
     }
 
@@ -534,6 +692,7 @@ public void testToImmutableBiMap_exceptionOnDuplicateKey_java7_combine() {
 
   public static class BiMapSpecificTests extends TestCase {
 
+    @SuppressWarnings("DoNotCall")
     public void testForcePut() {
       BiMap<String, Integer> bimap = ImmutableBiMap.copyOf(ImmutableMap.of("one", 1, "two", 2));
       try {
@@ -593,11 +752,11 @@ public void testInverseSerialization() {
   }
 
   private static <K, V> void assertMapEquals(Map<K, V> map, Object... alternatingKeysAndValues) {
-    int i = 0;
-    for (Entry<K, V> entry : map.entrySet()) {
-      assertEquals(alternatingKeysAndValues[i++], entry.getKey());
-      assertEquals(alternatingKeysAndValues[i++], entry.getValue());
+    Map<Object, Object> expected = new LinkedHashMap<>();
+    for (int i = 0; i < alternatingKeysAndValues.length; i += 2) {
+      expected.put(alternatingKeysAndValues[i], alternatingKeysAndValues[i + 1]);
     }
+    assertThat(map).containsExactlyEntriesIn(expected).inOrder();
   }
 
   /** No-op test so that the class has at least one method, making Maven's test runner happy. */
diff --git a/android/guava-tests/test/com/google/common/collect/ImmutableListMultimapTest.java b/android/guava-tests/test/com/google/common/collect/ImmutableListMultimapTest.java
index 768ebecde560..126074004224 100644
--- a/android/guava-tests/test/com/google/common/collect/ImmutableListMultimapTest.java
+++ b/android/guava-tests/test/com/google/common/collect/ImmutableListMultimapTest.java
@@ -29,6 +29,7 @@
 import com.google.common.collect.testing.google.TestStringListMultimapGenerator;
 import com.google.common.collect.testing.google.UnmodifiableCollectionTests;
 import com.google.common.testing.EqualsTester;
+import com.google.common.testing.NullPointerTester;
 import com.google.common.testing.SerializableTester;
 import java.util.Arrays;
 import java.util.Collection;
@@ -571,4 +572,13 @@ public void testEmptySerialization() {
     Multimap<String, Integer> multimap = ImmutableListMultimap.of();
     assertSame(multimap, SerializableTester.reserialize(multimap));
   }
+
+  @GwtIncompatible // reflection
+  public void testNulls() throws Exception {
+    NullPointerTester tester = new NullPointerTester();
+    tester.testAllPublicStaticMethods(ImmutableListMultimap.class);
+    tester.ignore(ImmutableListMultimap.class.getMethod("get", Object.class));
+    tester.testAllPublicInstanceMethods(ImmutableListMultimap.of());
+    tester.testAllPublicInstanceMethods(ImmutableListMultimap.of("a", 1));
+  }
 }
diff --git a/android/guava-tests/test/com/google/common/collect/ImmutableMapTest.java b/android/guava-tests/test/com/google/common/collect/ImmutableMapTest.java
index fd27416c5922..898d2a4b490e 100644
--- a/android/guava-tests/test/com/google/common/collect/ImmutableMapTest.java
+++ b/android/guava-tests/test/com/google/common/collect/ImmutableMapTest.java
@@ -18,6 +18,7 @@
 
 import static com.google.common.testing.SerializableTester.reserialize;
 import static com.google.common.truth.Truth.assertThat;
+import static com.google.common.truth.Truth.assertWithMessage;
 
 import com.google.common.annotations.GwtCompatible;
 import com.google.common.annotations.GwtIncompatible;
@@ -49,12 +50,15 @@
 import java.io.ByteArrayOutputStream;
 import java.io.ObjectOutputStream;
 import java.io.Serializable;
+import java.util.AbstractMap;
 import java.util.Collection;
 import java.util.Collections;
 import java.util.LinkedHashMap;
 import java.util.Map;
 import java.util.Map.Entry;
 import java.util.Set;
+import java.util.regex.Matcher;
+import java.util.regex.Pattern;
 import junit.framework.Test;
 import junit.framework.TestCase;
 import junit.framework.TestSuite;
@@ -66,6 +70,7 @@
  * @author Jesse Wilson
  */
 @GwtCompatible(emulated = true)
+@SuppressWarnings("AlwaysThrows")
 public class ImmutableMapTest extends TestCase {
 
   @GwtIncompatible // suite
@@ -176,7 +181,7 @@ protected Map<K, V> makeEmptyMap() {
       throw new UnsupportedOperationException();
     }
 
-    private static final Joiner joiner = Joiner.on(", ");
+    private static final Joiner JOINER = Joiner.on(", ");
 
     @Override
     protected void assertMoreInvariants(Map<K, V> map) {
@@ -185,10 +190,10 @@ protected void assertMoreInvariants(Map<K, V> map) {
         assertEquals(entry.getKey() + "=" + entry.getValue(), entry.toString());
       }
 
-      assertEquals("{" + joiner.join(map.entrySet()) + "}", map.toString());
-      assertEquals("[" + joiner.join(map.entrySet()) + "]", map.entrySet().toString());
-      assertEquals("[" + joiner.join(map.keySet()) + "]", map.keySet().toString());
-      assertEquals("[" + joiner.join(map.values()) + "]", map.values().toString());
+      assertEquals("{" + JOINER.join(map.entrySet()) + "}", map.toString());
+      assertEquals("[" + JOINER.join(map.entrySet()) + "]", map.entrySet().toString());
+      assertEquals("[" + JOINER.join(map.keySet()) + "]", map.keySet().toString());
+      assertEquals("[" + JOINER.join(map.values()) + "]", map.values().toString());
 
       assertEquals(MinimalSet.from(map.entrySet()), map.entrySet());
       assertEquals(Sets.newHashSet(map.keySet()), map.keySet());
@@ -316,12 +321,13 @@ protected Map<Integer, UnhashableObject> makePopulatedMap() {
 
   public static class CreationTests extends TestCase {
     public void testEmptyBuilder() {
-      ImmutableMap<String, Integer> map = new Builder<String, Integer>().build();
+      ImmutableMap<String, Integer> map = new Builder<String, Integer>().buildOrThrow();
       assertEquals(Collections.<String, Integer>emptyMap(), map);
     }
 
     public void testSingletonBuilder() {
-      ImmutableMap<String, Integer> map = new Builder<String, Integer>().put("one", 1).build();
+      ImmutableMap<String, Integer> map =
+          new Builder<String, Integer>().put("one", 1).buildOrThrow();
       assertMapEquals(map, "one", 1);
     }
 
@@ -333,7 +339,7 @@ public void testBuilder() {
               .put("three", 3)
               .put("four", 4)
               .put("five", 5)
-              .build();
+              .buildOrThrow();
       assertMapEquals(map, "one", 1, "two", 2, "three", 3, "four", 4, "five", 5);
     }
 
@@ -346,7 +352,7 @@ public void testBuilderExactlySizedReusesArray() {
       }
       Object[] builderArrayAfterPuts = builder.alternatingKeysAndValues;
       RegularImmutableMap<Integer, Integer> map =
-          (RegularImmutableMap<Integer, Integer>) builder.build();
+          (RegularImmutableMap<Integer, Integer>) builder.buildOrThrow();
       Object[] mapInternalArray = map.alternatingKeysAndValues;
       assertSame(builderArray, builderArrayAfterPuts);
       assertSame(builderArray, mapInternalArray);
@@ -361,16 +367,16 @@ public void testBuilder_orderEntriesByValue() {
               .put("five", 5)
               .put("four", 4)
               .put("two", 2)
-              .build();
+              .buildOrThrow();
       assertMapEquals(map, "one", 1, "two", 2, "three", 3, "four", 4, "five", 5);
     }
 
     public void testBuilder_orderEntriesByValueAfterExactSizeBuild() {
       Builder<String, Integer> builder =
           new Builder<String, Integer>(2).put("four", 4).put("one", 1);
-      ImmutableMap<String, Integer> keyOrdered = builder.build();
+      ImmutableMap<String, Integer> keyOrdered = builder.buildOrThrow();
       ImmutableMap<String, Integer> valueOrdered =
-          builder.orderEntriesByValue(Ordering.natural()).build();
+          builder.orderEntriesByValue(Ordering.natural()).buildOrThrow();
       assertMapEquals(keyOrdered, "four", 4, "one", 1);
       assertMapEquals(valueOrdered, "one", 1, "four", 4);
     }
@@ -385,9 +391,45 @@ public void testBuilder_orderEntriesByValue_usedTwiceFails() {
       }
     }
 
+    @GwtIncompatible // we haven't implemented this
+    public void testBuilder_orderEntriesByValue_keepingLast() {
+      ImmutableMap.Builder<String, Integer> builder =
+          new Builder<String, Integer>()
+              .orderEntriesByValue(Ordering.natural())
+              .put("three", 3)
+              .put("one", 1)
+              .put("five", 5)
+              .put("four", 3)
+              .put("four", 5)
+              .put("four", 4) // this should win because it's last
+              .put("two", 2);
+      assertMapEquals(
+          builder.buildKeepingLast(), "one", 1, "two", 2, "three", 3, "four", 4, "five", 5);
+      try {
+        builder.buildOrThrow();
+        fail("Expected exception from duplicate keys");
+      } catch (IllegalArgumentException expected) {
+      }
+    }
+
+    @GwtIncompatible // we haven't implemented this
+    public void testBuilder_orderEntriesByValue_keepingLast_builderSizeFieldPreserved() {
+      ImmutableMap.Builder<String, Integer> builder =
+          new Builder<String, Integer>()
+              .orderEntriesByValue(Ordering.natural())
+              .put("one", 1)
+              .put("one", 1);
+      assertMapEquals(builder.buildKeepingLast(), "one", 1);
+      try {
+        builder.buildOrThrow();
+        fail("Expected exception from duplicate keys");
+      } catch (IllegalArgumentException expected) {
+      }
+    }
+
     public void testBuilder_withImmutableEntry() {
       ImmutableMap<String, Integer> map =
-          new Builder<String, Integer>().put(Maps.immutableEntry("one", 1)).build();
+          new Builder<String, Integer>().put(Maps.immutableEntry("one", 1)).buildOrThrow();
       assertMapEquals(map, "one", 1);
     }
 
@@ -428,12 +470,14 @@ public Integer getValue() {
 
       builder.put(entry);
       holder.string = "two";
-      assertMapEquals(builder.build(), "one", 1);
+      assertMapEquals(builder.buildOrThrow(), "one", 1);
     }
 
     public void testBuilderPutAllWithEmptyMap() {
       ImmutableMap<String, Integer> map =
-          new Builder<String, Integer>().putAll(Collections.<String, Integer>emptyMap()).build();
+          new Builder<String, Integer>()
+              .putAll(Collections.<String, Integer>emptyMap())
+              .buildOrThrow();
       assertEquals(Collections.<String, Integer>emptyMap(), map);
     }
 
@@ -447,14 +491,14 @@ public void testBuilderPutAll() {
       moreToPut.put("five", 5);
 
       ImmutableMap<String, Integer> map =
-          new Builder<String, Integer>().putAll(toPut).putAll(moreToPut).build();
+          new Builder<String, Integer>().putAll(toPut).putAll(moreToPut).buildOrThrow();
       assertMapEquals(map, "one", 1, "two", 2, "three", 3, "four", 4, "five", 5);
     }
 
     public void testBuilderReuse() {
       Builder<String, Integer> builder = new Builder<>();
-      ImmutableMap<String, Integer> mapOne = builder.put("one", 1).put("two", 2).build();
-      ImmutableMap<String, Integer> mapTwo = builder.put("three", 3).put("four", 4).build();
+      ImmutableMap<String, Integer> mapOne = builder.put("one", 1).put("two", 2).buildOrThrow();
+      ImmutableMap<String, Integer> mapTwo = builder.put("three", 3).put("four", 4).buildOrThrow();
 
       assertMapEquals(mapOne, "one", 1, "two", 2);
       assertMapEquals(mapTwo, "one", 1, "two", 2, "three", 3, "four", 4);
@@ -468,7 +512,7 @@ public void testBuilderPutNullKeyFailsAtomically() {
       } catch (NullPointerException expected) {
       }
       builder.put("foo", 2);
-      assertMapEquals(builder.build(), "foo", 2);
+      assertMapEquals(builder.buildOrThrow(), "foo", 2);
     }
 
     public void testBuilderPutImmutableEntryWithNullKeyFailsAtomically() {
@@ -479,7 +523,7 @@ public void testBuilderPutImmutableEntryWithNullKeyFailsAtomically() {
       } catch (NullPointerException expected) {
       }
       builder.put("foo", 2);
-      assertMapEquals(builder.build(), "foo", 2);
+      assertMapEquals(builder.buildOrThrow(), "foo", 2);
     }
 
     // for GWT compatibility
@@ -511,7 +555,7 @@ public void testBuilderPutMutableEntryWithNullKeyFailsAtomically() {
       } catch (NullPointerException expected) {
       }
       builder.put("foo", 2);
-      assertMapEquals(builder.build(), "foo", 2);
+      assertMapEquals(builder.buildOrThrow(), "foo", 2);
     }
 
     public void testBuilderPutNullKey() {
@@ -554,15 +598,108 @@ public void testPuttingTheSameKeyTwiceThrowsOnBuild() {
       Builder<String, Integer> builder =
           new Builder<String, Integer>()
               .put("one", 1)
-              .put("one", 1); // throwing on this line would be even better
+              .put("one", 1); // throwing on this line might be better but it's too late to change
 
       try {
-        builder.build();
+        builder.buildOrThrow();
         fail();
       } catch (IllegalArgumentException expected) {
       }
     }
 
+    public void testBuildKeepingLast_allowsOverwrite() {
+      Builder<Integer, String> builder =
+          new Builder<Integer, String>()
+              .put(1, "un")
+              .put(2, "deux")
+              .put(70, "soixante-dix")
+              .put(70, "septante")
+              .put(70, "seventy")
+              .put(1, "one")
+              .put(2, "two");
+      ImmutableMap<Integer, String> map = builder.buildKeepingLast();
+      assertMapEquals(map, 1, "one", 2, "two", 70, "seventy");
+    }
+
+    public void testBuildKeepingLast_smallTableSameHash() {
+      String key1 = "QED";
+      String key2 = "R&D";
+      assertThat(key1.hashCode()).isEqualTo(key2.hashCode());
+      ImmutableMap<String, Integer> map =
+          ImmutableMap.<String, Integer>builder()
+              .put(key1, 1)
+              .put(key2, 2)
+              .put(key1, 3)
+              .put(key2, 4)
+              .buildKeepingLast();
+      assertMapEquals(map, key1, 3, key2, 4);
+    }
+
+    // The java7 branch has different code depending on whether the entry indexes fit in a byte,
+    // short, or int. The small table in testBuildKeepingLast_allowsOverwrite will test the byte
+    // case. This method tests the short case.
+    public void testBuildKeepingLast_shortTable() {
+      Builder<Integer, String> builder = ImmutableMap.builder();
+      Map<Integer, String> expected = new LinkedHashMap<>();
+      for (int i = 0; i < 1000; i++) {
+        // Truncate to even key, so we have put(0, "0") then put(0, "1"). Half the entries are
+        // duplicates.
+        Integer key = i & ~1;
+        String value = String.valueOf(i);
+        builder.put(key, value);
+        expected.put(key, value);
+      }
+      ImmutableMap<Integer, String> map = builder.buildKeepingLast();
+      assertThat(map).hasSize(500);
+      assertThat(map).containsExactlyEntriesIn(expected).inOrder();
+    }
+
+    // This method tests the int case.
+    public void testBuildKeepingLast_bigTable() {
+      Builder<Integer, String> builder = ImmutableMap.builder();
+      Map<Integer, String> expected = new LinkedHashMap<>();
+      for (int i = 0; i < 200_000; i++) {
+        // Truncate to even key, so we have put(0, "0") then put(0, "1"). Half the entries are
+        // duplicates.
+        Integer key = i & ~1;
+        String value = String.valueOf(i);
+        builder.put(key, value);
+        expected.put(key, value);
+      }
+      ImmutableMap<Integer, String> map = builder.buildKeepingLast();
+      assertThat(map).hasSize(100_000);
+      assertThat(map).containsExactlyEntriesIn(expected).inOrder();
+    }
+
+    @GwtIncompatible // Pattern, Matcher
+    public void testBuilder_keepingLast_thenOrThrow() {
+      ImmutableMap.Builder<String, Integer> builder =
+          new Builder<String, Integer>()
+              .put("three", 3)
+              .put("one", 1)
+              .put("five", 5)
+              .put("four", 3)
+              .put("four", 5)
+              .put("four", 4) // this should win because it's last
+              .put("two", 2);
+      assertMapEquals(
+          builder.buildKeepingLast(), "three", 3, "one", 1, "five", 5, "four", 4, "two", 2);
+      try {
+        builder.buildOrThrow();
+        fail("Expected exception from duplicate keys");
+      } catch (IllegalArgumentException expected) {
+        // We don't really care which values the exception message contains, but they should be
+        // different from each other. If buildKeepingLast() collapsed duplicates, that might end up
+        // not being true.
+        Pattern pattern =
+            Pattern.compile("Multiple entries with same key: four=(.*) and four=(.*)");
+        assertThat(expected).hasMessageThat().matches(pattern);
+        Matcher matcher = pattern.matcher(expected.getMessage());
+        assertThat(matcher.matches()).isTrue();
+        assertThat(matcher.group(1)).isNotEqualTo(matcher.group(2));
+      }
+    }
+
     public void testOf() {
       assertMapEquals(ImmutableMap.of("one", 1), "one", 1);
       assertMapEquals(ImmutableMap.of("one", 1, "two", 2), "one", 1, "two", 2);
@@ -590,6 +727,136 @@ public void testOf() {
           4,
           "five",
           5);
+      assertMapEquals(
+          ImmutableMap.of(
+              "one", 1,
+              "two", 2,
+              "three", 3,
+              "four", 4,
+              "five", 5,
+              "six", 6),
+          "one",
+          1,
+          "two",
+          2,
+          "three",
+          3,
+          "four",
+          4,
+          "five",
+          5,
+          "six",
+          6);
+      assertMapEquals(
+          ImmutableMap.of(
+              "one", 1,
+              "two", 2,
+              "three", 3,
+              "four", 4,
+              "five", 5,
+              "six", 6,
+              "seven", 7),
+          "one",
+          1,
+          "two",
+          2,
+          "three",
+          3,
+          "four",
+          4,
+          "five",
+          5,
+          "six",
+          6,
+          "seven",
+          7);
+      assertMapEquals(
+          ImmutableMap.of(
+              "one", 1,
+              "two", 2,
+              "three", 3,
+              "four", 4,
+              "five", 5,
+              "six", 6,
+              "seven", 7,
+              "eight", 8),
+          "one",
+          1,
+          "two",
+          2,
+          "three",
+          3,
+          "four",
+          4,
+          "five",
+          5,
+          "six",
+          6,
+          "seven",
+          7,
+          "eight",
+          8);
+      assertMapEquals(
+          ImmutableMap.of(
+              "one", 1,
+              "two", 2,
+              "three", 3,
+              "four", 4,
+              "five", 5,
+              "six", 6,
+              "seven", 7,
+              "eight", 8,
+              "nine", 9),
+          "one",
+          1,
+          "two",
+          2,
+          "three",
+          3,
+          "four",
+          4,
+          "five",
+          5,
+          "six",
+          6,
+          "seven",
+          7,
+          "eight",
+          8,
+          "nine",
+          9);
+      assertMapEquals(
+          ImmutableMap.of(
+              "one", 1,
+              "two", 2,
+              "three", 3,
+              "four", 4,
+              "five", 5,
+              "six", 6,
+              "seven", 7,
+              "eight", 8,
+              "nine", 9,
+              "ten", 10),
+          "one",
+          1,
+          "two",
+          2,
+          "three",
+          3,
+          "four",
+          4,
+          "five",
+          5,
+          "six",
+          6,
+          "seven",
+          7,
+          "eight",
+          8,
+          "nine",
+          9,
+          "ten",
+          10);
     }
 
     public void testOfNullKey() {
@@ -745,12 +1012,11 @@ public void testNullPointers() {
   }
 
   private static <K, V> void assertMapEquals(Map<K, V> map, Object... alternatingKeysAndValues) {
-    assertEquals(map.size(), alternatingKeysAndValues.length / 2);
-    int i = 0;
-    for (Entry<K, V> entry : map.entrySet()) {
-      assertEquals(alternatingKeysAndValues[i++], entry.getKey());
-      assertEquals(alternatingKeysAndValues[i++], entry.getValue());
+    Map<Object, Object> expected = new LinkedHashMap<>();
+    for (int i = 0; i < alternatingKeysAndValues.length; i += 2) {
+      expected.put(alternatingKeysAndValues[i], alternatingKeysAndValues[i + 1]);
     }
+    assertThat(map).containsExactlyEntriesIn(expected).inOrder();
   }
 
   private static class IntHolder implements Serializable {
@@ -849,15 +1115,87 @@ public void ignore_testSerializationNoDuplication_regularImmutableMap() throws E
 
   public void testEquals() {
     new EqualsTester()
-        .addEqualityGroup(ImmutableMap.of(), ImmutableMap.builder().build())
-        .addEqualityGroup(ImmutableMap.of(1, 1), ImmutableMap.builder().put(1, 1).build())
-        .addEqualityGroup(ImmutableMap.of(1, 1, 2, 2))
-        .addEqualityGroup(ImmutableMap.of(1, 1, 2, 2, 3, 3))
-        .addEqualityGroup(ImmutableMap.of(1, 4, 2, 2, 3, 3))
-        .addEqualityGroup(ImmutableMap.of(1, 1, 2, 4, 3, 3))
-        .addEqualityGroup(ImmutableMap.of(1, 1, 2, 2, 3, 4))
-        .addEqualityGroup(ImmutableMap.of(1, 2, 2, 3, 3, 1))
-        .addEqualityGroup(ImmutableMap.of(1, 1, 2, 2, 3, 3, 4, 4))
+        .addEqualityGroup(
+            ImmutableMap.of(),
+            ImmutableMap.builder().buildOrThrow(),
+            ImmutableMap.ofEntries(),
+            map())
+        .addEqualityGroup(
+            ImmutableMap.of(1, 1),
+            ImmutableMap.builder().put(1, 1).buildOrThrow(),
+            ImmutableMap.ofEntries(entry(1, 1)),
+            map(1, 1))
+        .addEqualityGroup(
+            ImmutableMap.of(1, 1, 2, 2),
+            ImmutableMap.builder().put(1, 1).put(2, 2).buildOrThrow(),
+            ImmutableMap.ofEntries(entry(1, 1), entry(2, 2)),
+            map(1, 1, 2, 2))
+        .addEqualityGroup(
+            ImmutableMap.of(1, 1, 2, 2, 3, 3),
+            ImmutableMap.builder().put(1, 1).put(2, 2).put(3, 3).buildOrThrow(),
+            ImmutableMap.ofEntries(entry(1, 1), entry(2, 2), entry(3, 3)),
+            map(1, 1, 2, 2, 3, 3))
+        .addEqualityGroup(
+            ImmutableMap.of(1, 4, 2, 2, 3, 3),
+            ImmutableMap.builder().put(1, 4).put(2, 2).put(3, 3).buildOrThrow(),
+            ImmutableMap.ofEntries(entry(1, 4), entry(2, 2), entry(3, 3)),
+            map(1, 4, 2, 2, 3, 3))
+        .addEqualityGroup(
+            ImmutableMap.of(1, 1, 2, 4, 3, 3),
+            ImmutableMap.builder().put(1, 1).put(2, 4).put(3, 3).buildOrThrow(),
+            ImmutableMap.ofEntries(entry(1, 1), entry(2, 4), entry(3, 3)),
+            map(1, 1, 2, 4, 3, 3))
+        .addEqualityGroup(
+            ImmutableMap.of(1, 1, 2, 2, 3, 4),
+            ImmutableMap.builder().put(1, 1).put(2, 2).put(3, 4).buildOrThrow(),
+            ImmutableMap.ofEntries(entry(1, 1), entry(2, 2), entry(3, 4)),
+            map(1, 1, 2, 2, 3, 4))
+        .addEqualityGroup(
+            ImmutableMap.of(1, 2, 2, 3, 3, 1),
+            ImmutableMap.builder().put(1, 2).put(2, 3).put(3, 1).buildOrThrow(),
+            ImmutableMap.ofEntries(entry(1, 2), entry(2, 3), entry(3, 1)),
+            map(1, 2, 2, 3, 3, 1))
+        .addEqualityGroup(
+            ImmutableMap.of(1, 1, 2, 2, 3, 3, 4, 4),
+            ImmutableMap.builder().put(1, 1).put(2, 2).put(3, 3).put(4, 4).buildOrThrow(),
+            ImmutableMap.ofEntries(entry(1, 1), entry(2, 2), entry(3, 3), entry(4, 4)),
+            map(1, 1, 2, 2, 3, 3, 4, 4))
+        .addEqualityGroup(
+            ImmutableMap.of(1, 1, 2, 2, 3, 3, 4, 4, 5, 5),
+            ImmutableMap.builder().put(1, 1).put(2, 2).put(3, 3).put(4, 4).put(5, 5).buildOrThrow(),
+            ImmutableMap.ofEntries(entry(1, 1), entry(2, 2), entry(3, 3), entry(4, 4), entry(5, 5)),
+            map(1, 1, 2, 2, 3, 3, 4, 4, 5, 5))
         .testEquals();
   }
+
+  public void testOfEntriesNull() {
+    Entry<Integer, Integer> nullKey = entry(null, 23);
+    try {
+      ImmutableMap.ofEntries(nullKey);
+      fail();
+    } catch (NullPointerException expected) {
+    }
+    Entry<Integer, Integer> nullValue = entry(23, null);
+    try {
+      ImmutableMap.ofEntries(nullValue);
+      fail();
+    } catch (NullPointerException expected) {
+    }
+  }
+
+  private static <T> Map<T, T> map(T... keysAndValues) {
+    assertThat(keysAndValues.length % 2).isEqualTo(0);
+    LinkedHashMap<T, T> map = new LinkedHashMap<>();
+    for (int i = 0; i < keysAndValues.length; i += 2) {
+      T key = keysAndValues[i];
+      T value = keysAndValues[i + 1];
+      T old = map.put(key, value);
+      assertWithMessage("Key %s set to %s and %s", key, value, old).that(old).isNull();
+    }
+    return map;
+  }
+
+  private static <T> Entry<T, T> entry(T key, T value) {
+    return new AbstractMap.SimpleImmutableEntry<>(key, value);
+  }
 }
diff --git a/android/guava-tests/test/com/google/common/collect/ImmutableMultimapTest.java b/android/guava-tests/test/com/google/common/collect/ImmutableMultimapTest.java
index 52632580c3e8..ac09593bac1d 100644
--- a/android/guava-tests/test/com/google/common/collect/ImmutableMultimapTest.java
+++ b/android/guava-tests/test/com/google/common/collect/ImmutableMultimapTest.java
@@ -17,11 +17,13 @@
 package com.google.common.collect;
 
 import com.google.common.annotations.GwtCompatible;
+import com.google.common.annotations.GwtIncompatible;
 import com.google.common.collect.ImmutableMultimap.Builder;
 import com.google.common.collect.testing.SampleElements;
 import com.google.common.collect.testing.SampleElements.Unhashables;
 import com.google.common.collect.testing.UnhashableObject;
 import com.google.common.testing.EqualsTester;
+import com.google.common.testing.NullPointerTester;
 import java.util.Arrays;
 import java.util.Map.Entry;
 import junit.framework.TestCase;
@@ -124,4 +126,13 @@ public void testEquals() {
             ImmutableMultimap.of(1, "a", 2, "b"), ImmutableMultimap.of(2, "b", 1, "a"))
         .testEquals();
   }
+
+  @GwtIncompatible // reflection
+  public void testNulls() throws Exception {
+    NullPointerTester tester = new NullPointerTester();
+    tester.testAllPublicStaticMethods(ImmutableMultimap.class);
+    tester.ignore(ImmutableListMultimap.class.getMethod("get", Object.class));
+    tester.testAllPublicInstanceMethods(ImmutableMultimap.of());
+    tester.testAllPublicInstanceMethods(ImmutableMultimap.of("a", 1));
+  }
 }
diff --git a/android/guava-tests/test/com/google/common/collect/ImmutableRangeSetTest.java b/android/guava-tests/test/com/google/common/collect/ImmutableRangeSetTest.java
index 5ca1f586199d..4c2bf3f92a83 100644
--- a/android/guava-tests/test/com/google/common/collect/ImmutableRangeSetTest.java
+++ b/android/guava-tests/test/com/google/common/collect/ImmutableRangeSetTest.java
@@ -312,6 +312,7 @@ public void testMultipleBoundedAboveRanges() {
     assertEquals(expectedComplement, rangeSet.complement());
   }
 
+  @SuppressWarnings("DoNotCall")
   public void testAddUnsupported() {
     RangeSet<Integer> rangeSet =
         ImmutableRangeSet.<Integer>builder()
@@ -327,6 +328,7 @@ public void testAddUnsupported() {
     }
   }
 
+  @SuppressWarnings("DoNotCall")
   public void testAddAllUnsupported() {
     RangeSet<Integer> rangeSet =
         ImmutableRangeSet.<Integer>builder()
@@ -342,6 +344,7 @@ public void testAddAllUnsupported() {
     }
   }
 
+  @SuppressWarnings("DoNotCall")
   public void testRemoveUnsupported() {
     RangeSet<Integer> rangeSet =
         ImmutableRangeSet.<Integer>builder()
@@ -357,6 +360,7 @@ public void testRemoveUnsupported() {
     }
   }
 
+  @SuppressWarnings("DoNotCall")
   public void testRemoveAllUnsupported() {
     RangeSet<Integer> rangeSet =
         ImmutableRangeSet.<Integer>builder()
diff --git a/android/guava-tests/test/com/google/common/collect/ImmutableSetMultimapTest.java b/android/guava-tests/test/com/google/common/collect/ImmutableSetMultimapTest.java
index 8690e948bd15..33d4ec1aa356 100644
--- a/android/guava-tests/test/com/google/common/collect/ImmutableSetMultimapTest.java
+++ b/android/guava-tests/test/com/google/common/collect/ImmutableSetMultimapTest.java
@@ -29,6 +29,7 @@
 import com.google.common.collect.testing.google.TestStringSetMultimapGenerator;
 import com.google.common.collect.testing.google.UnmodifiableCollectionTests;
 import com.google.common.testing.EqualsTester;
+import com.google.common.testing.NullPointerTester;
 import com.google.common.testing.SerializableTester;
 import java.util.Arrays;
 import java.util.Collection;
@@ -592,4 +593,13 @@ private ImmutableSetMultimap<String, Integer> createMultimap() {
         .put("foo", 3)
         .build();
   }
+
+  @GwtIncompatible // reflection
+  public void testNulls() throws Exception {
+    NullPointerTester tester = new NullPointerTester();
+    tester.testAllPublicStaticMethods(ImmutableSetMultimap.class);
+    tester.ignore(ImmutableSetMultimap.class.getMethod("get", Object.class));
+    tester.testAllPublicInstanceMethods(ImmutableSetMultimap.of());
+    tester.testAllPublicInstanceMethods(ImmutableSetMultimap.of("a", 1));
+  }
 }
diff --git a/android/guava-tests/test/com/google/common/collect/ImmutableSortedMapTest.java b/android/guava-tests/test/com/google/common/collect/ImmutableSortedMapTest.java
index 9f3a7706cd86..4a9178b4af6e 100644
--- a/android/guava-tests/test/com/google/common/collect/ImmutableSortedMapTest.java
+++ b/android/guava-tests/test/com/google/common/collect/ImmutableSortedMapTest.java
@@ -56,6 +56,7 @@
  * @author Jared Levy
  */
 @GwtCompatible(emulated = true)
+@SuppressWarnings("AlwaysThrows")
 public class ImmutableSortedMapTest extends TestCase {
   // TODO: Avoid duplicating code in ImmutableMapTest
 
@@ -482,6 +483,136 @@ public void testOf() {
           3,
           "two",
           2);
+      assertMapEquals(
+          ImmutableSortedMap.of(
+              "one", 1,
+              "two", 2,
+              "three", 3,
+              "four", 4,
+              "five", 5,
+              "six", 6),
+          "five",
+          5,
+          "four",
+          4,
+          "one",
+          1,
+          "six",
+          6,
+          "three",
+          3,
+          "two",
+          2);
+      assertMapEquals(
+          ImmutableSortedMap.of(
+              "one", 1,
+              "two", 2,
+              "three", 3,
+              "four", 4,
+              "five", 5,
+              "six", 6,
+              "seven", 7),
+          "five",
+          5,
+          "four",
+          4,
+          "one",
+          1,
+          "seven",
+          7,
+          "six",
+          6,
+          "three",
+          3,
+          "two",
+          2);
+      assertMapEquals(
+          ImmutableSortedMap.of(
+              "one", 1,
+              "two", 2,
+              "three", 3,
+              "four", 4,
+              "five", 5,
+              "six", 6,
+              "seven", 7,
+              "eight", 8),
+          "eight",
+          8,
+          "five",
+          5,
+          "four",
+          4,
+          "one",
+          1,
+          "seven",
+          7,
+          "six",
+          6,
+          "three",
+          3,
+          "two",
+          2);
+      assertMapEquals(
+          ImmutableSortedMap.of(
+              "one", 1,
+              "two", 2,
+              "three", 3,
+              "four", 4,
+              "five", 5,
+              "six", 6,
+              "seven", 7,
+              "eight", 8,
+              "nine", 9),
+          "eight",
+          8,
+          "five",
+          5,
+          "four",
+          4,
+          "nine",
+          9,
+          "one",
+          1,
+          "seven",
+          7,
+          "six",
+          6,
+          "three",
+          3,
+          "two",
+          2);
+      assertMapEquals(
+          ImmutableSortedMap.of(
+              "one", 1,
+              "two", 2,
+              "three", 3,
+              "four", 4,
+              "five", 5,
+              "six", 6,
+              "seven", 7,
+              "eight", 8,
+              "nine", 9,
+              "ten", 10),
+          "eight",
+          8,
+          "five",
+          5,
+          "four",
+          4,
+          "nine",
+          9,
+          "one",
+          1,
+          "seven",
+          7,
+          "six",
+          6,
+          "ten",
+          10,
+          "three",
+          3,
+          "two",
+          2);
     }
 
     public void testOfNullKey() {
@@ -745,12 +876,11 @@ public void testNullValuesInCopyOfEntries() {
   }
 
   private static <K, V> void assertMapEquals(Map<K, V> map, Object... alternatingKeysAndValues) {
-    assertEquals(map.size(), alternatingKeysAndValues.length / 2);
-    int i = 0;
-    for (Entry<K, V> entry : map.entrySet()) {
-      assertEquals(alternatingKeysAndValues[i++], entry.getKey());
-      assertEquals(alternatingKeysAndValues[i++], entry.getValue());
+    Map<Object, Object> expected = new LinkedHashMap<>();
+    for (int i = 0; i < alternatingKeysAndValues.length; i += 2) {
+      expected.put(alternatingKeysAndValues[i], alternatingKeysAndValues[i + 1]);
     }
+    assertThat(map).containsExactlyEntriesIn(expected).inOrder();
   }
 
   private static class IntHolder implements Serializable {
diff --git a/android/guava-tests/test/com/google/common/collect/ImmutableSortedSetTest.java b/android/guava-tests/test/com/google/common/collect/ImmutableSortedSetTest.java
index 2ebff40fe97a..ea0e3a8d16bc 100644
--- a/android/guava-tests/test/com/google/common/collect/ImmutableSortedSetTest.java
+++ b/android/guava-tests/test/com/google/common/collect/ImmutableSortedSetTest.java
@@ -915,7 +915,7 @@ public void testLegacyComparable_builder_reverse() {
     assertTrue(Iterables.elementsEqual(LegacyComparable.VALUES_BACKWARD, set));
   }
 
-  @SuppressWarnings({"deprecation", "static-access"})
+  @SuppressWarnings({"deprecation", "static-access", "DoNotCall"})
   public void testBuilderMethod() {
     try {
       ImmutableSortedSet.builder();
diff --git a/android/guava-tests/test/com/google/common/collect/IteratorsTest.java b/android/guava-tests/test/com/google/common/collect/IteratorsTest.java
index 15f7ccc2040a..e71c8bd51eea 100644
--- a/android/guava-tests/test/com/google/common/collect/IteratorsTest.java
+++ b/android/guava-tests/test/com/google/common/collect/IteratorsTest.java
@@ -74,6 +74,7 @@ public static Test suite() {
     return suite;
   }
 
+  @SuppressWarnings("DoNotCall")
   public void testEmptyIterator() {
     Iterator<String> iterator = Iterators.emptyIterator();
     assertFalse(iterator.hasNext());
@@ -89,6 +90,7 @@ public void testEmptyIterator() {
     }
   }
 
+  @SuppressWarnings("DoNotCall")
   public void testEmptyListIterator() {
     ListIterator<String> iterator = Iterators.emptyListIterator();
     assertFalse(iterator.hasNext());
@@ -1119,6 +1121,7 @@ public void testForArrayEmpty() {
     }
   }
 
+  @SuppressWarnings("DoNotCall")
   public void testForArrayTypical() {
     String[] array = {"foo", "bar"};
     Iterator<String> iterator = Iterators.forArray(array);
@@ -1205,6 +1208,7 @@ public void testForEnumerationEmpty() {
     }
   }
 
+  @SuppressWarnings("DoNotCall")
   public void testForEnumerationSingleton() {
     Enumeration<Integer> enumer = enumerate(1);
     Iterator<Integer> iter = Iterators.forEnumeration(enumer);
diff --git a/android/guava-tests/test/com/google/common/collect/LinkedListMultimapTest.java b/android/guava-tests/test/com/google/common/collect/LinkedListMultimapTest.java
index d57d5c044c87..b0d48f0f4d66 100644
--- a/android/guava-tests/test/com/google/common/collect/LinkedListMultimapTest.java
+++ b/android/guava-tests/test/com/google/common/collect/LinkedListMultimapTest.java
@@ -35,6 +35,7 @@
 import com.google.common.collect.testing.google.ListMultimapTestSuiteBuilder;
 import com.google.common.collect.testing.google.TestStringListMultimapGenerator;
 import com.google.common.testing.EqualsTester;
+import com.google.common.testing.NullPointerTester;
 import java.util.Arrays;
 import java.util.Collection;
 import java.util.Collections;
@@ -496,4 +497,13 @@ public void testEquals() {
             LinkedListMultimap.create(), LinkedListMultimap.create(), LinkedListMultimap.create(1))
         .testEquals();
   }
+
+  @GwtIncompatible // reflection
+  public void testNulls() throws Exception {
+    NullPointerTester tester = new NullPointerTester();
+    tester.testAllPublicStaticMethods(LinkedListMultimap.class);
+    tester.ignore(LinkedListMultimap.class.getMethod("get", Object.class));
+    tester.ignore(LinkedListMultimap.class.getMethod("removeAll", Object.class));
+    tester.testAllPublicInstanceMethods(LinkedListMultimap.create());
+  }
 }
diff --git a/android/guava-tests/test/com/google/common/collect/ListsTest.java b/android/guava-tests/test/com/google/common/collect/ListsTest.java
index ef90e5493f96..33736d6d8116 100644
--- a/android/guava-tests/test/com/google/common/collect/ListsTest.java
+++ b/android/guava-tests/test/com/google/common/collect/ListsTest.java
@@ -619,14 +619,14 @@ public void testCartesianProduct_contains() {
 
   public void testCartesianProduct_indexOf() {
     List<List<Integer>> actual = Lists.cartesianProduct(list(1, 2), list(3, 4));
-    assertEquals(actual.indexOf(list(1, 3)), 0);
-    assertEquals(actual.indexOf(list(1, 4)), 1);
-    assertEquals(actual.indexOf(list(2, 3)), 2);
-    assertEquals(actual.indexOf(list(2, 4)), 3);
-    assertEquals(actual.indexOf(list(3, 1)), -1);
-
-    assertEquals(actual.indexOf(list(1)), -1);
-    assertEquals(actual.indexOf(list(1, 1, 1)), -1);
+    assertEquals(0, actual.indexOf(list(1, 3)));
+    assertEquals(1, actual.indexOf(list(1, 4)));
+    assertEquals(2, actual.indexOf(list(2, 3)));
+    assertEquals(3, actual.indexOf(list(2, 4)));
+    assertEquals(-1, actual.indexOf(list(3, 1)));
+
+    assertEquals(-1, actual.indexOf(list(1)));
+    assertEquals(-1, actual.indexOf(list(1, 1, 1)));
   }
 
   public void testCartesianProduct_lastIndexOf() {
diff --git a/android/guava-tests/test/com/google/common/collect/MapMakerTest.java b/android/guava-tests/test/com/google/common/collect/MapMakerTest.java
index 4b54f0dd5350..9669ded7c302 100644
--- a/android/guava-tests/test/com/google/common/collect/MapMakerTest.java
+++ b/android/guava-tests/test/com/google/common/collect/MapMakerTest.java
@@ -57,31 +57,28 @@ public T apply(T key) {
    * anywhere else
    */
 
-  /** Tests for the builder. */
-  public static class MakerTest extends TestCase {
-    public void testInitialCapacity_negative() {
-      MapMaker maker = new MapMaker();
-      try {
-        maker.initialCapacity(-1);
-        fail();
-      } catch (IllegalArgumentException expected) {
-      }
+  public void testInitialCapacity_negative() {
+    MapMaker maker = new MapMaker();
+    try {
+      maker.initialCapacity(-1);
+      fail();
+    } catch (IllegalArgumentException expected) {
     }
+  }
 
-    // TODO(cpovirk): enable when ready
-    public void xtestInitialCapacity_setTwice() {
-      MapMaker maker = new MapMaker().initialCapacity(16);
-      try {
-        // even to the same value is not allowed
-        maker.initialCapacity(16);
-        fail();
-      } catch (IllegalArgumentException expected) {
-      }
+  // TODO(cpovirk): enable when ready (apparently after a change to our GWT emulation)
+  public void xtestInitialCapacity_setTwice() {
+    MapMaker maker = new MapMaker().initialCapacity(16);
+    try {
+      // even to the same value is not allowed
+      maker.initialCapacity(16);
+      fail();
+    } catch (IllegalStateException expected) {
     }
+  }
 
-    public void testReturnsPlainConcurrentHashMapWhenPossible() {
-      Map<?, ?> map = new MapMaker().initialCapacity(5).makeMap();
-      assertTrue(map instanceof ConcurrentHashMap);
-    }
+  public void testReturnsPlainConcurrentHashMapWhenPossible() {
+    Map<?, ?> map = new MapMaker().initialCapacity(5).makeMap();
+    assertTrue(map instanceof ConcurrentHashMap);
   }
 }
diff --git a/android/guava-tests/test/com/google/common/collect/MapsCollectionTest.java b/android/guava-tests/test/com/google/common/collect/MapsCollectionTest.java
index 54aa1aa2e65e..9aa8e66b70fb 100644
--- a/android/guava-tests/test/com/google/common/collect/MapsCollectionTest.java
+++ b/android/guava-tests/test/com/google/common/collect/MapsCollectionTest.java
@@ -49,10 +49,10 @@
 import java.util.Set;
 import java.util.SortedMap;
 import java.util.SortedSet;
+import javax.annotation.CheckForNull;
 import junit.framework.Test;
 import junit.framework.TestCase;
 import junit.framework.TestSuite;
-import org.checkerframework.checker.nullness.compatqual.NullableDecl;
 
 /**
  * Test suites for wrappers in {@code Maps}.
@@ -561,7 +561,7 @@ static void putEntries(Map<String, String> map, Entry<String, String>[] entries)
   static final Predicate<String> FILTER_KEYS =
       new Predicate<String>() {
         @Override
-        public boolean apply(@NullableDecl String string) {
+        public boolean apply(@CheckForNull String string) {
           return !"banana".equals(string) && !"eggplant".equals(string);
         }
       };
@@ -569,7 +569,7 @@ public boolean apply(@NullableDecl String string) {
   static final Predicate<String> FILTER_VALUES =
       new Predicate<String>() {
         @Override
-        public boolean apply(@NullableDecl String string) {
+        public boolean apply(@CheckForNull String string) {
           return !"toast".equals(string) && !"spam".equals(string);
         }
       };
diff --git a/android/guava-tests/test/com/google/common/collect/MapsTest.java b/android/guava-tests/test/com/google/common/collect/MapsTest.java
index 76394c883498..d0f98386346d 100644
--- a/android/guava-tests/test/com/google/common/collect/MapsTest.java
+++ b/android/guava-tests/test/com/google/common/collect/MapsTest.java
@@ -1153,8 +1153,8 @@ public void testAsConverter_isAView() throws Exception {
     biMap.put("two", 2);
     Converter<String, Integer> converter = Maps.asConverter(biMap);
 
-    assertSame(1, converter.convert("one"));
-    assertSame(2, converter.convert("two"));
+    assertEquals((Integer) 1, converter.convert("one"));
+    assertEquals((Integer) 2, converter.convert("two"));
     try {
       converter.convert("three");
       fail();
@@ -1163,9 +1163,9 @@ public void testAsConverter_isAView() throws Exception {
 
     biMap.put("three", 3);
 
-    assertSame(1, converter.convert("one"));
-    assertSame(2, converter.convert("two"));
-    assertSame(3, converter.convert("three"));
+    assertEquals((Integer) 1, converter.convert("one"));
+    assertEquals((Integer) 2, converter.convert("two"));
+    assertEquals((Integer) 3, converter.convert("three"));
   }
 
   public void testAsConverter_withNullMapping() throws Exception {
diff --git a/android/guava-tests/test/com/google/common/collect/MapsTransformValuesTest.java b/android/guava-tests/test/com/google/common/collect/MapsTransformValuesTest.java
index d81f546c55cb..b4382dbcacd0 100644
--- a/android/guava-tests/test/com/google/common/collect/MapsTransformValuesTest.java
+++ b/android/guava-tests/test/com/google/common/collect/MapsTransformValuesTest.java
@@ -25,7 +25,7 @@
 import java.util.Map;
 import java.util.Map.Entry;
 import java.util.Set;
-import org.checkerframework.checker.nullness.compatqual.NullableDecl;
+import javax.annotation.CheckForNull;
 
 /**
  * Tests for {@link Maps#transformValues}.
@@ -156,7 +156,7 @@ public void testTransformEqualityOfMapsWithNullValues() {
             underlying,
             new Function<String, Boolean>() {
               @Override
-              public Boolean apply(@NullableDecl String from) {
+              public Boolean apply(@CheckForNull String from) {
                 return from == null;
               }
             });
@@ -274,7 +274,7 @@ public void testTransformEntrySetContains() {
             underlying,
             new Function<Boolean, Boolean>() {
               @Override
-              public Boolean apply(@NullableDecl Boolean from) {
+              public Boolean apply(@CheckForNull Boolean from) {
                 return (from == null) ? true : null;
               }
             });
diff --git a/android/guava-tests/test/com/google/common/collect/MapsTransformValuesUnmodifiableIteratorTest.java b/android/guava-tests/test/com/google/common/collect/MapsTransformValuesUnmodifiableIteratorTest.java
index 81a2d935bdbf..10739513f0c1 100644
--- a/android/guava-tests/test/com/google/common/collect/MapsTransformValuesUnmodifiableIteratorTest.java
+++ b/android/guava-tests/test/com/google/common/collect/MapsTransformValuesUnmodifiableIteratorTest.java
@@ -25,7 +25,7 @@
 import java.util.Map;
 import java.util.Map.Entry;
 import java.util.Set;
-import org.checkerframework.checker.nullness.compatqual.NullableDecl;
+import javax.annotation.CheckForNull;
 
 /**
  * Tests for {@link Maps#transformValues} when the backing map's views have iterators that don't
@@ -232,7 +232,7 @@ public void testTransformEqualityOfMapsWithNullValues() {
             underlying,
             new Function<String, Boolean>() {
               @Override
-              public Boolean apply(@NullableDecl String from) {
+              public Boolean apply(@CheckForNull String from) {
                 return from == null;
               }
             });
@@ -350,7 +350,7 @@ public void testTransformEntrySetContains() {
             underlying,
             new Function<Boolean, Boolean>() {
               @Override
-              public Boolean apply(@NullableDecl Boolean from) {
+              public Boolean apply(@CheckForNull Boolean from) {
                 return (from == null) ? true : null;
               }
             });
diff --git a/android/guava-tests/test/com/google/common/collect/MultimapsTest.java b/android/guava-tests/test/com/google/common/collect/MultimapsTest.java
index 1a8f84e5ab9e..02ea574bbc50 100644
--- a/android/guava-tests/test/com/google/common/collect/MultimapsTest.java
+++ b/android/guava-tests/test/com/google/common/collect/MultimapsTest.java
@@ -55,8 +55,8 @@
 import java.util.SortedMap;
 import java.util.SortedSet;
 import java.util.TreeSet;
+import javax.annotation.CheckForNull;
 import junit.framework.TestCase;
-import org.checkerframework.checker.nullness.compatqual.NullableDecl;
 
 /**
  * Unit test for {@code Multimaps}.
@@ -267,8 +267,8 @@ private static void checkUnmodifiableMultimap(
   private static void checkUnmodifiableMultimap(
       Multimap<String, Integer> multimap,
       boolean permitsDuplicates,
-      @NullableDecl String nullKey,
-      @NullableDecl Integer nullValue) {
+      @CheckForNull String nullKey,
+      @CheckForNull Integer nullValue) {
     Multimap<String, Integer> unmodifiable =
         prepareUnmodifiableTests(multimap, permitsDuplicates, nullKey, nullValue);
 
@@ -297,8 +297,8 @@ private static void checkUnmodifiableMultimap(
   private static Multimap<String, Integer> prepareUnmodifiableTests(
       Multimap<String, Integer> multimap,
       boolean permitsDuplicates,
-      @NullableDecl String nullKey,
-      @NullableDecl Integer nullValue) {
+      @CheckForNull String nullKey,
+      @CheckForNull Integer nullValue) {
     multimap.clear();
     multimap.put("foo", 1);
     multimap.put("foo", 2);
@@ -610,7 +610,8 @@ public void testNewMultimap() {
     assertEquals("[3, 1, 4]", ummodifiable.get(Color.BLUE).toString());
 
     Collection<Integer> collection = multimap.get(Color.BLUE);
-    assertEquals(collection, collection);
+    // Explicitly call `equals`; `assertEquals` might return fast
+    assertTrue(collection.equals(collection));
 
     assertFalse(multimap.keySet() instanceof SortedSet);
     assertFalse(multimap.asMap() instanceof SortedMap);
diff --git a/android/guava-tests/test/com/google/common/collect/OrderingTest.java b/android/guava-tests/test/com/google/common/collect/OrderingTest.java
index b449a29ee34c..7c4acc943159 100644
--- a/android/guava-tests/test/com/google/common/collect/OrderingTest.java
+++ b/android/guava-tests/test/com/google/common/collect/OrderingTest.java
@@ -40,8 +40,8 @@
 import java.util.List;
 import java.util.Random;
 import java.util.RandomAccess;
+import javax.annotation.CheckForNull;
 import junit.framework.TestCase;
-import org.checkerframework.checker.nullness.compatqual.NullableDecl;
 
 /**
  * Unit tests for {@code Ordering}.
@@ -1030,7 +1030,7 @@ <T> Scenario<?> mutate(final Scenario<T> scenario) {
             scenario.ordering.onResultOf(
                 new Function<Integer, T>() {
                   @Override
-                  public T apply(@NullableDecl Integer from) {
+                  public T apply(@CheckForNull Integer from) {
                     return scenario.strictlyOrderedList.get(from);
                   }
                 });
diff --git a/android/guava-tests/test/com/google/common/collect/RangeTest.java b/android/guava-tests/test/com/google/common/collect/RangeTest.java
index 9a2cd74161a8..e8578bfd199b 100644
--- a/android/guava-tests/test/com/google/common/collect/RangeTest.java
+++ b/android/guava-tests/test/com/google/common/collect/RangeTest.java
@@ -20,6 +20,7 @@
 import static com.google.common.collect.BoundType.OPEN;
 import static com.google.common.collect.DiscreteDomain.integers;
 import static com.google.common.testing.SerializableTester.reserializeAndAssert;
+import static com.google.common.truth.Truth.assertThat;
 import static java.util.Arrays.asList;
 
 import com.google.common.annotations.GwtCompatible;
@@ -349,11 +350,14 @@ public void testIntersection_empty() {
       range.intersection(Range.open(3, 5));
       fail();
     } catch (IllegalArgumentException expected) {
+      // TODO(kevinb): convert the rest of this file to Truth someday
+      assertThat(expected).hasMessageThat().contains("connected");
     }
     try {
       range.intersection(Range.closed(0, 2));
       fail();
     } catch (IllegalArgumentException expected) {
+      assertThat(expected).hasMessageThat().contains("connected");
     }
   }
 
@@ -368,11 +372,13 @@ public void testIntersection_deFactoEmpty() {
       range.intersection(Range.lessThan(3));
       fail();
     } catch (IllegalArgumentException expected) {
+      assertThat(expected).hasMessageThat().contains("connected");
     }
     try {
       range.intersection(Range.greaterThan(4));
       fail();
     } catch (IllegalArgumentException expected) {
+      assertThat(expected).hasMessageThat().contains("connected");
     }
 
     range = Range.closed(3, 4);
@@ -395,11 +401,13 @@ public void testIntersection_singleton() {
       range.intersection(Range.atLeast(4));
       fail();
     } catch (IllegalArgumentException expected) {
+      assertThat(expected).hasMessageThat().contains("connected");
     }
     try {
       range.intersection(Range.atMost(2));
       fail();
     } catch (IllegalArgumentException expected) {
+      assertThat(expected).hasMessageThat().contains("connected");
     }
   }
 
@@ -411,6 +419,7 @@ public void testIntersection_general() {
       range.intersection(Range.closed(0, 2));
       fail();
     } catch (IllegalArgumentException expected) {
+      assertThat(expected).hasMessageThat().contains("connected");
     }
 
     // adjacent below
@@ -451,6 +460,7 @@ public void testIntersection_general() {
       range.intersection(Range.closed(10, 12));
       fail();
     } catch (IllegalArgumentException expected) {
+      assertThat(expected).hasMessageThat().contains("connected");
     }
   }
 
diff --git a/android/guava-tests/test/com/google/common/collect/RegularImmutableAsListTest.java b/android/guava-tests/test/com/google/common/collect/RegularImmutableAsListTest.java
index b6c2358c590a..b0f9e16e4327 100644
--- a/android/guava-tests/test/com/google/common/collect/RegularImmutableAsListTest.java
+++ b/android/guava-tests/test/com/google/common/collect/RegularImmutableAsListTest.java
@@ -30,7 +30,8 @@ public class RegularImmutableAsListTest extends TestCase {
    */
   public void testDoesntCheckForNull() {
     ImmutableSet<Integer> set = ImmutableSet.of(1, 2, 3);
-    new RegularImmutableAsList<Integer>(set, new Object[] {null, null, null});
+    ImmutableList<Integer> unused =
+        new RegularImmutableAsList<Integer>(set, new Object[] {null, null, null});
     // shouldn't throw!
   }
 }
diff --git a/android/guava-tests/test/com/google/common/collect/SetOperationsTest.java b/android/guava-tests/test/com/google/common/collect/SetOperationsTest.java
index 7a1ec3a6590c..9a26f29457b3 100644
--- a/android/guava-tests/test/com/google/common/collect/SetOperationsTest.java
+++ b/android/guava-tests/test/com/google/common/collect/SetOperationsTest.java
@@ -291,92 +291,90 @@ protected Set<String> create(String[] elements) {
             .withFeatures(CollectionSize.ANY, CollectionFeature.ALLOWS_NULL_VALUES)
             .createTestSuite());
 
-    suite.addTestSuite(MoreTests.class);
+    suite.addTestSuite(SetOperationsTest.class);
     return suite;
   }
 
-  public static class MoreTests extends TestCase {
-    Set<String> friends;
-    Set<String> enemies;
-
-    @Override
-    public void setUp() {
-      friends = Sets.newHashSet("Tom", "Joe", "Dave");
-      enemies = Sets.newHashSet("Dick", "Harry", "Tom");
-    }
-
-    public void testUnion() {
-      Set<String> all = Sets.union(friends, enemies);
-      assertEquals(5, all.size());
-
-      ImmutableSet<String> immut = Sets.union(friends, enemies).immutableCopy();
-      HashSet<String> mut = Sets.union(friends, enemies).copyInto(new HashSet<String>());
-
-      enemies.add("Buck");
-      assertEquals(6, all.size());
-      assertEquals(5, immut.size());
-      assertEquals(5, mut.size());
-    }
-
-    public void testIntersection() {
-      Set<String> friends = Sets.newHashSet("Tom", "Joe", "Dave");
-      Set<String> enemies = Sets.newHashSet("Dick", "Harry", "Tom");
-
-      Set<String> frenemies = Sets.intersection(friends, enemies);
-      assertEquals(1, frenemies.size());
-
-      ImmutableSet<String> immut = Sets.intersection(friends, enemies).immutableCopy();
-      HashSet<String> mut = Sets.intersection(friends, enemies).copyInto(new HashSet<String>());
-
-      enemies.add("Joe");
-      assertEquals(2, frenemies.size());
-      assertEquals(1, immut.size());
-      assertEquals(1, mut.size());
-    }
-
-    public void testDifference() {
-      Set<String> friends = Sets.newHashSet("Tom", "Joe", "Dave");
-      Set<String> enemies = Sets.newHashSet("Dick", "Harry", "Tom");
-
-      Set<String> goodFriends = Sets.difference(friends, enemies);
-      assertEquals(2, goodFriends.size());
-
-      ImmutableSet<String> immut = Sets.difference(friends, enemies).immutableCopy();
-      HashSet<String> mut = Sets.difference(friends, enemies).copyInto(new HashSet<String>());
-
-      enemies.add("Dave");
-      assertEquals(1, goodFriends.size());
-      assertEquals(2, immut.size());
-      assertEquals(2, mut.size());
-    }
-
-    public void testSymmetricDifference() {
-      Set<String> friends = Sets.newHashSet("Tom", "Joe", "Dave");
-      Set<String> enemies = Sets.newHashSet("Dick", "Harry", "Tom");
-
-      Set<String> symmetricDifferenceFriendsFirst = Sets.symmetricDifference(friends, enemies);
-      assertEquals(4, symmetricDifferenceFriendsFirst.size());
-
-      Set<String> symmetricDifferenceEnemiesFirst = Sets.symmetricDifference(enemies, friends);
-      assertEquals(4, symmetricDifferenceEnemiesFirst.size());
-
-      assertEquals(symmetricDifferenceFriendsFirst, symmetricDifferenceEnemiesFirst);
-
-      ImmutableSet<String> immut = Sets.symmetricDifference(friends, enemies).immutableCopy();
-      HashSet<String> mut =
-          Sets.symmetricDifference(friends, enemies).copyInto(new HashSet<String>());
-
-      enemies.add("Dave");
-      assertEquals(3, symmetricDifferenceFriendsFirst.size());
-      assertEquals(4, immut.size());
-      assertEquals(4, mut.size());
-
-      immut = Sets.symmetricDifference(enemies, friends).immutableCopy();
-      mut = Sets.symmetricDifference(enemies, friends).copyInto(new HashSet<String>());
-      friends.add("Harry");
-      assertEquals(2, symmetricDifferenceEnemiesFirst.size());
-      assertEquals(3, immut.size());
-      assertEquals(3, mut.size());
-    }
+  Set<String> friends;
+  Set<String> enemies;
+
+  @Override
+  public void setUp() {
+    friends = Sets.newHashSet("Tom", "Joe", "Dave");
+    enemies = Sets.newHashSet("Dick", "Harry", "Tom");
+  }
+
+  public void testUnion() {
+    Set<String> all = Sets.union(friends, enemies);
+    assertEquals(5, all.size());
+
+    ImmutableSet<String> immut = Sets.union(friends, enemies).immutableCopy();
+    HashSet<String> mut = Sets.union(friends, enemies).copyInto(new HashSet<String>());
+
+    enemies.add("Buck");
+    assertEquals(6, all.size());
+    assertEquals(5, immut.size());
+    assertEquals(5, mut.size());
+  }
+
+  public void testIntersection() {
+    Set<String> friends = Sets.newHashSet("Tom", "Joe", "Dave");
+    Set<String> enemies = Sets.newHashSet("Dick", "Harry", "Tom");
+
+    Set<String> frenemies = Sets.intersection(friends, enemies);
+    assertEquals(1, frenemies.size());
+
+    ImmutableSet<String> immut = Sets.intersection(friends, enemies).immutableCopy();
+    HashSet<String> mut = Sets.intersection(friends, enemies).copyInto(new HashSet<String>());
+
+    enemies.add("Joe");
+    assertEquals(2, frenemies.size());
+    assertEquals(1, immut.size());
+    assertEquals(1, mut.size());
+  }
+
+  public void testDifference() {
+    Set<String> friends = Sets.newHashSet("Tom", "Joe", "Dave");
+    Set<String> enemies = Sets.newHashSet("Dick", "Harry", "Tom");
+
+    Set<String> goodFriends = Sets.difference(friends, enemies);
+    assertEquals(2, goodFriends.size());
+
+    ImmutableSet<String> immut = Sets.difference(friends, enemies).immutableCopy();
+    HashSet<String> mut = Sets.difference(friends, enemies).copyInto(new HashSet<String>());
+
+    enemies.add("Dave");
+    assertEquals(1, goodFriends.size());
+    assertEquals(2, immut.size());
+    assertEquals(2, mut.size());
+  }
+
+  public void testSymmetricDifference() {
+    Set<String> friends = Sets.newHashSet("Tom", "Joe", "Dave");
+    Set<String> enemies = Sets.newHashSet("Dick", "Harry", "Tom");
+
+    Set<String> symmetricDifferenceFriendsFirst = Sets.symmetricDifference(friends, enemies);
+    assertEquals(4, symmetricDifferenceFriendsFirst.size());
+
+    Set<String> symmetricDifferenceEnemiesFirst = Sets.symmetricDifference(enemies, friends);
+    assertEquals(4, symmetricDifferenceEnemiesFirst.size());
+
+    assertEquals(symmetricDifferenceFriendsFirst, symmetricDifferenceEnemiesFirst);
+
+    ImmutableSet<String> immut = Sets.symmetricDifference(friends, enemies).immutableCopy();
+    HashSet<String> mut =
+        Sets.symmetricDifference(friends, enemies).copyInto(new HashSet<String>());
+
+    enemies.add("Dave");
+    assertEquals(3, symmetricDifferenceFriendsFirst.size());
+    assertEquals(4, immut.size());
+    assertEquals(4, mut.size());
+
+    immut = Sets.symmetricDifference(enemies, friends).immutableCopy();
+    mut = Sets.symmetricDifference(enemies, friends).copyInto(new HashSet<String>());
+    friends.add("Harry");
+    assertEquals(2, symmetricDifferenceEnemiesFirst.size());
+    assertEquals(3, immut.size());
+    assertEquals(3, mut.size());
   }
 }
diff --git a/android/guava-tests/test/com/google/common/collect/SetsTest.java b/android/guava-tests/test/com/google/common/collect/SetsTest.java
index 8aa8d8312452..d7799cec0c8a 100644
--- a/android/guava-tests/test/com/google/common/collect/SetsTest.java
+++ b/android/guava-tests/test/com/google/common/collect/SetsTest.java
@@ -73,10 +73,10 @@
 import java.util.SortedSet;
 import java.util.TreeSet;
 import java.util.concurrent.CopyOnWriteArraySet;
+import javax.annotation.CheckForNull;
 import junit.framework.Test;
 import junit.framework.TestCase;
 import junit.framework.TestSuite;
-import org.checkerframework.checker.nullness.compatqual.NullableDecl;
 
 /**
  * Unit test for {@code Sets}.
@@ -325,6 +325,7 @@ private enum SomeEnum {
     D
   }
 
+  @SuppressWarnings("DoNotCall")
   public void testImmutableEnumSet() {
     Set<SomeEnum> units = Sets.immutableEnumSet(SomeEnum.D, SomeEnum.B);
 
@@ -1076,7 +1077,7 @@ private static <E> void verifyLinkedHashSetContents(
    * same as the given comparator.
    */
   private static <E> void verifySortedSetContents(
-      SortedSet<E> set, Iterable<E> iterable, @NullableDecl Comparator<E> comparator) {
+      SortedSet<E> set, Iterable<E> iterable, @CheckForNull Comparator<E> comparator) {
     assertSame(comparator, set.comparator());
     verifySetContents(set, iterable);
   }
diff --git a/android/guava-tests/test/com/google/common/collect/SimpleAbstractMultisetTest.java b/android/guava-tests/test/com/google/common/collect/SimpleAbstractMultisetTest.java
index 830536dfc5db..02ab44b9f5c3 100644
--- a/android/guava-tests/test/com/google/common/collect/SimpleAbstractMultisetTest.java
+++ b/android/guava-tests/test/com/google/common/collect/SimpleAbstractMultisetTest.java
@@ -28,10 +28,10 @@
 import java.util.Iterator;
 import java.util.Map;
 import java.util.concurrent.atomic.AtomicInteger;
+import javax.annotation.CheckForNull;
 import junit.framework.Test;
 import junit.framework.TestCase;
 import junit.framework.TestSuite;
-import org.checkerframework.checker.nullness.compatqual.NullableDecl;
 
 /**
  * Unit test for {@link AbstractMultiset}.
@@ -106,7 +106,7 @@ public void clear() {
     }
 
     @Override
-    public int count(@NullableDecl Object element) {
+    public int count(@CheckForNull Object element) {
       for (Entry<E> entry : entrySet()) {
         if (Objects.equal(entry.getElement(), element)) {
           return entry.getCount();
@@ -116,7 +116,7 @@ public int count(@NullableDecl Object element) {
     }
 
     @Override
-    public int add(@NullableDecl E element, int occurrences) {
+    public int add(@CheckForNull E element, int occurrences) {
       checkArgument(occurrences >= 0);
       Integer frequency = backingMap.get(element);
       if (frequency == null) {
diff --git a/android/guava-tests/test/com/google/common/collect/SynchronizedDequeTest.java b/android/guava-tests/test/com/google/common/collect/SynchronizedDequeTest.java
index 0a11b27ab9ba..1df6aa1bffd1 100644
--- a/android/guava-tests/test/com/google/common/collect/SynchronizedDequeTest.java
+++ b/android/guava-tests/test/com/google/common/collect/SynchronizedDequeTest.java
@@ -254,6 +254,7 @@ public Iterator<E> descendingIterator() {
     private static final long serialVersionUID = 0;
   }
 
+  @SuppressWarnings("CheckReturnValue")
   public void testHoldsLockOnAllOperations() {
     create().element();
     create().offer("foo");
@@ -263,8 +264,8 @@ public void testHoldsLockOnAllOperations() {
     create().add("foo");
     create().addAll(ImmutableList.of("foo"));
     create().clear();
-    boolean unused = create().contains("foo");
-    boolean unused2 = create().containsAll(ImmutableList.of("foo"));
+    create().contains("foo");
+    create().containsAll(ImmutableList.of("foo"));
     create().equals(new ArrayDeque<>(ImmutableList.of("foo")));
     create().hashCode();
     create().isEmpty();
diff --git a/android/guava-tests/test/com/google/common/collect/SynchronizedMapTest.java b/android/guava-tests/test/com/google/common/collect/SynchronizedMapTest.java
index 34d1c6f4a067..2e15eda327a5 100644
--- a/android/guava-tests/test/com/google/common/collect/SynchronizedMapTest.java
+++ b/android/guava-tests/test/com/google/common/collect/SynchronizedMapTest.java
@@ -159,11 +159,11 @@ public String toString() {
    */
 
   public void testSize() {
-    create().size();
+    int unused = create().size();
   }
 
   public void testIsEmpty() {
-    create().isEmpty();
+    boolean unused = create().isEmpty();
   }
 
   public void testRemove() {
@@ -216,15 +216,15 @@ public void testEntrySet() {
   }
 
   public void testEquals() {
-    create().equals(new HashMap<String, Integer>());
+    boolean unused = create().equals(new HashMap<String, Integer>());
   }
 
   public void testHashCode() {
-    create().hashCode();
+    int unused = create().hashCode();
   }
 
   public void testToString() {
-    create().toString();
+    String unused = create().toString();
   }
 
   public void testSerialization() {
diff --git a/android/guava-tests/test/com/google/common/collect/SynchronizedMultimapTest.java b/android/guava-tests/test/com/google/common/collect/SynchronizedMultimapTest.java
index 14111da785f4..3c4f1375a0ab 100644
--- a/android/guava-tests/test/com/google/common/collect/SynchronizedMultimapTest.java
+++ b/android/guava-tests/test/com/google/common/collect/SynchronizedMultimapTest.java
@@ -30,10 +30,10 @@
 import java.util.Map.Entry;
 import java.util.RandomAccess;
 import java.util.Set;
+import javax.annotation.CheckForNull;
 import junit.framework.Test;
 import junit.framework.TestCase;
 import junit.framework.TestSuite;
-import org.checkerframework.checker.nullness.compatqual.NullableDecl;
 
 /**
  * Tests for {@code Synchronized#multimap}.
@@ -89,7 +89,7 @@ public String toString() {
     }
 
     @Override
-    public boolean equals(@NullableDecl Object o) {
+    public boolean equals(@CheckForNull Object o) {
       assertTrue(Thread.holdsLock(mutex));
       return super.equals(o);
     }
@@ -113,25 +113,25 @@ public boolean isEmpty() {
     }
 
     @Override
-    public boolean containsKey(@NullableDecl Object key) {
+    public boolean containsKey(@CheckForNull Object key) {
       assertTrue(Thread.holdsLock(mutex));
       return super.containsKey(key);
     }
 
     @Override
-    public boolean containsValue(@NullableDecl Object value) {
+    public boolean containsValue(@CheckForNull Object value) {
       assertTrue(Thread.holdsLock(mutex));
       return super.containsValue(value);
     }
 
     @Override
-    public boolean containsEntry(@NullableDecl Object key, @NullableDecl Object value) {
+    public boolean containsEntry(@CheckForNull Object key, @CheckForNull Object value) {
       assertTrue(Thread.holdsLock(mutex));
       return super.containsEntry(key, value);
     }
 
     @Override
-    public Set<V> get(@NullableDecl K key) {
+    public Set<V> get(@CheckForNull K key) {
       assertTrue(Thread.holdsLock(mutex));
       /* TODO: verify that the Collection is also synchronized? */
       return super.get(key);
@@ -144,7 +144,7 @@ public boolean put(K key, V value) {
     }
 
     @Override
-    public boolean putAll(@NullableDecl K key, Iterable<? extends V> values) {
+    public boolean putAll(@CheckForNull K key, Iterable<? extends V> values) {
       assertTrue(Thread.holdsLock(mutex));
       return super.putAll(key, values);
     }
@@ -156,19 +156,19 @@ public boolean putAll(Multimap<? extends K, ? extends V> map) {
     }
 
     @Override
-    public Set<V> replaceValues(@NullableDecl K key, Iterable<? extends V> values) {
+    public Set<V> replaceValues(@CheckForNull K key, Iterable<? extends V> values) {
       assertTrue(Thread.holdsLock(mutex));
       return super.replaceValues(key, values);
     }
 
     @Override
-    public boolean remove(@NullableDecl Object key, @NullableDecl Object value) {
+    public boolean remove(@CheckForNull Object key, @CheckForNull Object value) {
       assertTrue(Thread.holdsLock(mutex));
       return super.remove(key, value);
     }
 
     @Override
-    public Set<V> removeAll(@NullableDecl Object key) {
+    public Set<V> removeAll(@CheckForNull Object key) {
       assertTrue(Thread.holdsLock(mutex));
       return super.removeAll(key);
     }
diff --git a/android/guava-tests/test/com/google/common/collect/SynchronizedQueueTest.java b/android/guava-tests/test/com/google/common/collect/SynchronizedQueueTest.java
index 70ff7740a114..f7b04fe2e864 100644
--- a/android/guava-tests/test/com/google/common/collect/SynchronizedQueueTest.java
+++ b/android/guava-tests/test/com/google/common/collect/SynchronizedQueueTest.java
@@ -152,6 +152,7 @@ public <T> T[] toArray(T[] array) {
     private static final long serialVersionUID = 0;
   }
 
+  @SuppressWarnings("CheckReturnValue")
   public void testHoldsLockOnAllOperations() {
     create().element();
     create().offer("foo");
@@ -161,8 +162,8 @@ public void testHoldsLockOnAllOperations() {
     create().add("foo");
     create().addAll(ImmutableList.of("foo"));
     create().clear();
-    boolean unused = create().contains("foo");
-    boolean unused2 = create().containsAll(ImmutableList.of("foo"));
+    create().contains("foo");
+    create().containsAll(ImmutableList.of("foo"));
     create().equals(new ArrayDeque<>(ImmutableList.of("foo")));
     create().hashCode();
     create().isEmpty();
diff --git a/android/guava-tests/test/com/google/common/collect/SynchronizedSetTest.java b/android/guava-tests/test/com/google/common/collect/SynchronizedSetTest.java
index 746ad3fc1cc6..5ffcf5d54bf7 100644
--- a/android/guava-tests/test/com/google/common/collect/SynchronizedSetTest.java
+++ b/android/guava-tests/test/com/google/common/collect/SynchronizedSetTest.java
@@ -27,9 +27,9 @@
 import java.util.Collections;
 import java.util.HashSet;
 import java.util.Set;
+import javax.annotation.CheckForNull;
 import junit.framework.Test;
 import junit.framework.TestCase;
-import org.checkerframework.checker.nullness.compatqual.NullableDecl;
 
 /**
  * Tests for {@code Synchronized#set}.
@@ -82,7 +82,7 @@ public String toString() {
     }
 
     @Override
-    public boolean equals(@NullableDecl Object o) {
+    public boolean equals(@CheckForNull Object o) {
       assertTrue(Thread.holdsLock(mutex));
       return super.equals(o);
     }
@@ -94,7 +94,7 @@ public int hashCode() {
     }
 
     @Override
-    public boolean add(@NullableDecl E o) {
+    public boolean add(@CheckForNull E o) {
       assertTrue(Thread.holdsLock(mutex));
       return super.add(o);
     }
@@ -112,7 +112,7 @@ public void clear() {
     }
 
     @Override
-    public boolean contains(@NullableDecl Object o) {
+    public boolean contains(@CheckForNull Object o) {
       assertTrue(Thread.holdsLock(mutex));
       return super.contains(o);
     }
@@ -132,7 +132,7 @@ public boolean isEmpty() {
     /* Don't test iterator(); it may or may not hold the mutex. */
 
     @Override
-    public boolean remove(@NullableDecl Object o) {
+    public boolean remove(@CheckForNull Object o) {
       assertTrue(Thread.holdsLock(mutex));
       return super.remove(o);
     }
diff --git a/android/guava-tests/test/com/google/common/collect/SynchronizedTableTest.java b/android/guava-tests/test/com/google/common/collect/SynchronizedTableTest.java
index f418367eae76..e1b45443660c 100644
--- a/android/guava-tests/test/com/google/common/collect/SynchronizedTableTest.java
+++ b/android/guava-tests/test/com/google/common/collect/SynchronizedTableTest.java
@@ -20,7 +20,7 @@
 import java.util.Collection;
 import java.util.Map;
 import java.util.Set;
-import org.checkerframework.checker.nullness.compatqual.NullableDecl;
+import javax.annotation.CheckForNull;
 
 public class SynchronizedTableTest extends AbstractTableTest {
   private static final class TestTable<R, C, V> implements Table<R, C, V>, Serializable {
@@ -34,7 +34,7 @@ public String toString() {
     }
 
     @Override
-    public boolean equals(@NullableDecl Object o) {
+    public boolean equals(@CheckForNull Object o) {
       assertTrue(Thread.holdsLock(mutex));
       return delegate.equals(o);
     }
@@ -58,7 +58,7 @@ public boolean isEmpty() {
     }
 
     @Override
-    public boolean containsValue(@NullableDecl Object value) {
+    public boolean containsValue(@CheckForNull Object value) {
       assertTrue(Thread.holdsLock(mutex));
       return delegate.containsValue(value);
     }
diff --git a/android/guava-tests/test/com/google/common/collect/TopKSelectorTest.java b/android/guava-tests/test/com/google/common/collect/TopKSelectorTest.java
index e21f81703c30..2cebdc338b08 100644
--- a/android/guava-tests/test/com/google/common/collect/TopKSelectorTest.java
+++ b/android/guava-tests/test/com/google/common/collect/TopKSelectorTest.java
@@ -18,6 +18,7 @@
 
 import static com.google.common.truth.Truth.assertThat;
 
+import com.google.common.annotations.GwtCompatible;
 import com.google.common.math.IntMath;
 import com.google.common.primitives.Ints;
 import java.math.RoundingMode;
@@ -31,6 +32,7 @@
  *
  * @author Louis Wasserman
  */
+@GwtCompatible
 public class TopKSelectorTest extends TestCase {
 
   public void testNegativeK() {
@@ -119,4 +121,13 @@ public int compare(Integer o1, Integer o2) {
     assertThat(top.topK()).containsExactlyElementsIn(Collections.nCopies(k, 0));
     assertThat(compareCalls[0]).isAtMost(10L * n * IntMath.log2(k, RoundingMode.CEILING));
   }
+
+  public void testExceedMaxIteration() {
+    /*
+     * Bug #5692 occurred when TopKSelector called Arrays.sort incorrectly.
+     */
+    TopKSelector<Integer> top = TopKSelector.least(7);
+    top.offerAll(Ints.asList(5, 7, 6, 2, 4, 3, 1, 0, 0, 0, 0, 0, 0, 0));
+    assertThat(top.topK()).isEqualTo(Ints.asList(0, 0, 0, 0, 0, 0, 0));
+  }
 }
diff --git a/android/guava-tests/test/com/google/common/collect/UnmodifiableIteratorTest.java b/android/guava-tests/test/com/google/common/collect/UnmodifiableIteratorTest.java
index 77ecbf730362..5e474aa70f67 100644
--- a/android/guava-tests/test/com/google/common/collect/UnmodifiableIteratorTest.java
+++ b/android/guava-tests/test/com/google/common/collect/UnmodifiableIteratorTest.java
@@ -29,6 +29,7 @@
 @GwtCompatible
 public class UnmodifiableIteratorTest extends TestCase {
 
+  @SuppressWarnings("DoNotCall")
   public void testRemove() {
     final String[] array = {"a", "b", "c"};
 
diff --git a/android/guava-tests/test/com/google/common/collect/UnmodifiableListIteratorTest.java b/android/guava-tests/test/com/google/common/collect/UnmodifiableListIteratorTest.java
index c9d3068e0773..36a017d45cb3 100644
--- a/android/guava-tests/test/com/google/common/collect/UnmodifiableListIteratorTest.java
+++ b/android/guava-tests/test/com/google/common/collect/UnmodifiableListIteratorTest.java
@@ -29,6 +29,7 @@
  */
 @GwtCompatible
 public class UnmodifiableListIteratorTest extends TestCase {
+  @SuppressWarnings("DoNotCall")
   public void testRemove() {
     Iterator<String> iterator = create();
 
@@ -41,6 +42,7 @@ public void testRemove() {
     }
   }
 
+  @SuppressWarnings("DoNotCall")
   public void testAdd() {
     ListIterator<String> iterator = create();
 
@@ -55,6 +57,7 @@ public void testAdd() {
     }
   }
 
+  @SuppressWarnings("DoNotCall")
   public void testSet() {
     ListIterator<String> iterator = create();
 
diff --git a/android/guava-tests/test/com/google/common/escape/EscapersTest.java b/android/guava-tests/test/com/google/common/escape/EscapersTest.java
index 245560af61d5..442232030e0d 100644
--- a/android/guava-tests/test/com/google/common/escape/EscapersTest.java
+++ b/android/guava-tests/test/com/google/common/escape/EscapersTest.java
@@ -85,7 +85,7 @@ public void testAsUnicodeEscaper() throws IOException {
                 .put('x', "<hello>".toCharArray())
                 .put('\uD800', "<hi>".toCharArray())
                 .put('\uDC00', "<lo>".toCharArray())
-                .build());
+                .buildOrThrow());
     UnicodeEscaper unicodeEscaper = Escapers.asUnicodeEscaper(charEscaper);
     EscaperAsserts.assertBasic(unicodeEscaper);
     assertEquals("<hello><hi><lo>", charEscaper.escape("x\uD800\uDC00"));
diff --git a/android/guava-tests/test/com/google/common/eventbus/PackageSanityTests.java b/android/guava-tests/test/com/google/common/eventbus/PackageSanityTests.java
index 5dee7ca45303..225e55500df3 100644
--- a/android/guava-tests/test/com/google/common/eventbus/PackageSanityTests.java
+++ b/android/guava-tests/test/com/google/common/eventbus/PackageSanityTests.java
@@ -18,7 +18,7 @@
 
 import com.google.common.testing.AbstractPackageSanityTests;
 import java.lang.reflect.Method;
-import org.checkerframework.checker.nullness.compatqual.NullableDecl;
+import javax.annotation.CheckForNull;
 
 /**
  * Basic sanity tests for the entire package.
@@ -41,7 +41,7 @@ private static class DummySubscriber {
     private final EventBus eventBus = new EventBus();
 
     @Subscribe
-    public void handle(@NullableDecl Object anything) {}
+    public void handle(@CheckForNull Object anything) {}
 
     Subscriber toSubscriber() throws Exception {
       return Subscriber.create(eventBus, this, subscriberMethod());
diff --git a/android/guava-tests/test/com/google/common/eventbus/StringCatcher.java b/android/guava-tests/test/com/google/common/eventbus/StringCatcher.java
index 282abe11bac3..198fa2eda8ca 100644
--- a/android/guava-tests/test/com/google/common/eventbus/StringCatcher.java
+++ b/android/guava-tests/test/com/google/common/eventbus/StringCatcher.java
@@ -18,8 +18,8 @@
 
 import com.google.common.collect.Lists;
 import java.util.List;
+import javax.annotation.CheckForNull;
 import junit.framework.Assert;
-import org.checkerframework.checker.nullness.compatqual.NullableDecl;
 
 /**
  * A simple EventSubscriber mock that records Strings.
@@ -33,11 +33,11 @@ public class StringCatcher {
   private List<String> events = Lists.newArrayList();
 
   @Subscribe
-  public void hereHaveAString(@NullableDecl String string) {
+  public void hereHaveAString(@CheckForNull String string) {
     events.add(string);
   }
 
-  public void methodWithoutAnnotation(@NullableDecl String string) {
+  public void methodWithoutAnnotation(@CheckForNull String string) {
     Assert.fail("Event bus must not call methods without @Subscribe!");
   }
 
diff --git a/android/guava-tests/test/com/google/common/eventbus/outside/AbstractEventBusTest.java b/android/guava-tests/test/com/google/common/eventbus/outside/AbstractEventBusTest.java
new file mode 100644
index 000000000000..f4af7a7516de
--- /dev/null
+++ b/android/guava-tests/test/com/google/common/eventbus/outside/AbstractEventBusTest.java
@@ -0,0 +1,55 @@
+/*
+ * Copyright (C) 2012 The Guava Authors
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package com.google.common.eventbus.outside;
+
+import com.google.common.eventbus.EventBus;
+import junit.framework.TestCase;
+
+/**
+ * Abstract base class for tests that EventBus finds the correct subscribers.
+ *
+ * <p>The actual tests are distributed among the other classes in this package based on whether they
+ * are annotated or abstract in the superclass.
+ *
+ * <p>This test must be outside the c.g.c.eventbus package to test correctly.
+ *
+ * @author Louis Wasserman
+ */
+abstract class AbstractEventBusTest<H> extends TestCase {
+  static final Object EVENT = new Object();
+
+  abstract H createSubscriber();
+
+  private H subscriber;
+
+  H getSubscriber() {
+    return subscriber;
+  }
+
+  @Override
+  protected void setUp() throws Exception {
+    subscriber = createSubscriber();
+    EventBus bus = new EventBus();
+    bus.register(subscriber);
+    bus.post(EVENT);
+  }
+
+  @Override
+  protected void tearDown() throws Exception {
+    subscriber = null;
+  }
+}
diff --git a/android/guava-tests/test/com/google/common/eventbus/outside/AbstractNotAnnotatedInSuperclassTest.java b/android/guava-tests/test/com/google/common/eventbus/outside/AbstractNotAnnotatedInSuperclassTest.java
new file mode 100644
index 000000000000..a391fcbad687
--- /dev/null
+++ b/android/guava-tests/test/com/google/common/eventbus/outside/AbstractNotAnnotatedInSuperclassTest.java
@@ -0,0 +1,61 @@
+/*
+ * Copyright (C) 2012 The Guava Authors
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package com.google.common.eventbus.outside;
+
+import static com.google.common.truth.Truth.assertThat;
+
+import com.google.common.collect.Lists;
+import com.google.common.eventbus.Subscribe;
+import com.google.common.eventbus.outside.AbstractNotAnnotatedInSuperclassTest.SubClass;
+import java.util.List;
+
+public class AbstractNotAnnotatedInSuperclassTest extends AbstractEventBusTest<SubClass> {
+  abstract static class SuperClass {
+    public abstract void overriddenInSubclassNowhereAnnotated(Object o);
+
+    public abstract void overriddenAndAnnotatedInSubclass(Object o);
+  }
+
+  static class SubClass extends SuperClass {
+    final List<Object> overriddenInSubclassNowhereAnnotatedEvents = Lists.newArrayList();
+    final List<Object> overriddenAndAnnotatedInSubclassEvents = Lists.newArrayList();
+
+    @Override
+    public void overriddenInSubclassNowhereAnnotated(Object o) {
+      overriddenInSubclassNowhereAnnotatedEvents.add(o);
+    }
+
+    @Subscribe
+    @Override
+    public void overriddenAndAnnotatedInSubclass(Object o) {
+      overriddenAndAnnotatedInSubclassEvents.add(o);
+    }
+  }
+
+  public void testOverriddenAndAnnotatedInSubclass() {
+    assertThat(getSubscriber().overriddenAndAnnotatedInSubclassEvents).contains(EVENT);
+  }
+
+  public void testOverriddenInSubclassNowhereAnnotated() {
+    assertThat(getSubscriber().overriddenInSubclassNowhereAnnotatedEvents).isEmpty();
+  }
+
+  @Override
+  SubClass createSubscriber() {
+    return new SubClass();
+  }
+}
diff --git a/android/guava-tests/test/com/google/common/eventbus/outside/AnnotatedAndAbstractInSuperclassTest.java b/android/guava-tests/test/com/google/common/eventbus/outside/AnnotatedAndAbstractInSuperclassTest.java
new file mode 100644
index 000000000000..aea17c3b41e7
--- /dev/null
+++ b/android/guava-tests/test/com/google/common/eventbus/outside/AnnotatedAndAbstractInSuperclassTest.java
@@ -0,0 +1,63 @@
+/*
+ * Copyright (C) 2012 The Guava Authors
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package com.google.common.eventbus.outside;
+
+import static com.google.common.truth.Truth.assertThat;
+
+import com.google.common.collect.Lists;
+import com.google.common.eventbus.Subscribe;
+import com.google.common.eventbus.outside.AnnotatedAndAbstractInSuperclassTest.SubClass;
+import java.util.List;
+
+public class AnnotatedAndAbstractInSuperclassTest extends AbstractEventBusTest<SubClass> {
+  abstract static class SuperClass {
+    @Subscribe
+    public abstract void overriddenAndAnnotatedInSubclass(Object o);
+
+    @Subscribe
+    public abstract void overriddenInSubclass(Object o);
+  }
+
+  static class SubClass extends SuperClass {
+    final List<Object> overriddenAndAnnotatedInSubclassEvents = Lists.newArrayList();
+    final List<Object> overriddenInSubclassEvents = Lists.newArrayList();
+
+    @Subscribe
+    @Override
+    public void overriddenAndAnnotatedInSubclass(Object o) {
+      overriddenAndAnnotatedInSubclassEvents.add(o);
+    }
+
+    @Override
+    public void overriddenInSubclass(Object o) {
+      overriddenInSubclassEvents.add(o);
+    }
+  }
+
+  public void testOverriddenAndAnnotatedInSubclass() {
+    assertThat(getSubscriber().overriddenAndAnnotatedInSubclassEvents).contains(EVENT);
+  }
+
+  public void testOverriddenNotAnnotatedInSubclass() {
+    assertThat(getSubscriber().overriddenInSubclassEvents).contains(EVENT);
+  }
+
+  @Override
+  SubClass createSubscriber() {
+    return new SubClass();
+  }
+}
diff --git a/android/guava-tests/test/com/google/common/eventbus/outside/AnnotatedNotAbstractInSuperclassTest.java b/android/guava-tests/test/com/google/common/eventbus/outside/AnnotatedNotAbstractInSuperclassTest.java
new file mode 100644
index 000000000000..3ec8ea4709f9
--- /dev/null
+++ b/android/guava-tests/test/com/google/common/eventbus/outside/AnnotatedNotAbstractInSuperclassTest.java
@@ -0,0 +1,116 @@
+/*
+ * Copyright (C) 2012 The Guava Authors
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package com.google.common.eventbus.outside;
+
+import static com.google.common.truth.Truth.assertThat;
+
+import com.google.common.collect.Lists;
+import com.google.common.eventbus.Subscribe;
+import com.google.common.eventbus.outside.AnnotatedNotAbstractInSuperclassTest.SubClass;
+import java.util.List;
+
+public class AnnotatedNotAbstractInSuperclassTest extends AbstractEventBusTest<SubClass> {
+  static class SuperClass {
+    final List<Object> notOverriddenInSubclassEvents = Lists.newArrayList();
+    final List<Object> overriddenNotAnnotatedInSubclassEvents = Lists.newArrayList();
+    final List<Object> overriddenAndAnnotatedInSubclassEvents = Lists.newArrayList();
+    final List<Object> differentlyOverriddenNotAnnotatedInSubclassBadEvents = Lists.newArrayList();
+    final List<Object> differentlyOverriddenAnnotatedInSubclassBadEvents = Lists.newArrayList();
+
+    @Subscribe
+    public void notOverriddenInSubclass(Object o) {
+      notOverriddenInSubclassEvents.add(o);
+    }
+
+    @Subscribe
+    public void overriddenNotAnnotatedInSubclass(Object o) {
+      overriddenNotAnnotatedInSubclassEvents.add(o);
+    }
+
+    @Subscribe
+    public void overriddenAndAnnotatedInSubclass(Object o) {
+      overriddenAndAnnotatedInSubclassEvents.add(o);
+    }
+
+    @Subscribe
+    public void differentlyOverriddenNotAnnotatedInSubclass(Object o) {
+      // the subclass overrides this and does *not* call super.dONAIS(o)
+      differentlyOverriddenNotAnnotatedInSubclassBadEvents.add(o);
+    }
+
+    @Subscribe
+    public void differentlyOverriddenAnnotatedInSubclass(Object o) {
+      // the subclass overrides this and does *not* call super.dOAIS(o)
+      differentlyOverriddenAnnotatedInSubclassBadEvents.add(o);
+    }
+  }
+
+  static class SubClass extends SuperClass {
+    final List<Object> differentlyOverriddenNotAnnotatedInSubclassGoodEvents = Lists.newArrayList();
+    final List<Object> differentlyOverriddenAnnotatedInSubclassGoodEvents = Lists.newArrayList();
+
+    @Override
+    public void overriddenNotAnnotatedInSubclass(Object o) {
+      super.overriddenNotAnnotatedInSubclass(o);
+    }
+
+    @Subscribe
+    @Override
+    public void overriddenAndAnnotatedInSubclass(Object o) {
+      super.overriddenAndAnnotatedInSubclass(o);
+    }
+
+    @Override
+    public void differentlyOverriddenNotAnnotatedInSubclass(Object o) {
+      differentlyOverriddenNotAnnotatedInSubclassGoodEvents.add(o);
+    }
+
+    @Subscribe
+    @Override
+    public void differentlyOverriddenAnnotatedInSubclass(Object o) {
+      differentlyOverriddenAnnotatedInSubclassGoodEvents.add(o);
+    }
+  }
+
+  public void testNotOverriddenInSubclass() {
+    assertThat(getSubscriber().notOverriddenInSubclassEvents).contains(EVENT);
+  }
+
+  public void testOverriddenNotAnnotatedInSubclass() {
+    assertThat(getSubscriber().overriddenNotAnnotatedInSubclassEvents).contains(EVENT);
+  }
+
+  public void testDifferentlyOverriddenNotAnnotatedInSubclass() {
+    assertThat(getSubscriber().differentlyOverriddenNotAnnotatedInSubclassGoodEvents)
+        .contains(EVENT);
+    assertThat(getSubscriber().differentlyOverriddenNotAnnotatedInSubclassBadEvents).isEmpty();
+  }
+
+  public void testOverriddenAndAnnotatedInSubclass() {
+    assertThat(getSubscriber().overriddenAndAnnotatedInSubclassEvents).contains(EVENT);
+  }
+
+  public void testDifferentlyOverriddenAndAnnotatedInSubclass() {
+    assertThat(getSubscriber().differentlyOverriddenAnnotatedInSubclassGoodEvents).contains(EVENT);
+    assertThat(getSubscriber().differentlyOverriddenAnnotatedInSubclassBadEvents).isEmpty();
+  }
+
+  @Override
+  SubClass createSubscriber() {
+    return new SubClass();
+  }
+}
diff --git a/android/guava-tests/test/com/google/common/eventbus/outside/AnnotatedSubscriberFinderTests.java b/android/guava-tests/test/com/google/common/eventbus/outside/AnnotatedSubscriberFinderTests.java
deleted file mode 100644
index a1cbb594481e..000000000000
--- a/android/guava-tests/test/com/google/common/eventbus/outside/AnnotatedSubscriberFinderTests.java
+++ /dev/null
@@ -1,448 +0,0 @@
-/*
- * Copyright (C) 2012 The Guava Authors
- *
- * Licensed under the Apache License, Version 2.0 (the "License");
- * you may not use this file except in compliance with the License.
- * You may obtain a copy of the License at
- *
- * http://www.apache.org/licenses/LICENSE-2.0
- *
- * Unless required by applicable law or agreed to in writing, software
- * distributed under the License is distributed on an "AS IS" BASIS,
- * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
- * See the License for the specific language governing permissions and
- * limitations under the License.
- */
-
-package com.google.common.eventbus.outside;
-
-import static com.google.common.truth.Truth.assertThat;
-
-import com.google.common.collect.Lists;
-import com.google.common.eventbus.EventBus;
-import com.google.common.eventbus.Subscribe;
-import java.util.List;
-import junit.framework.TestCase;
-
-/**
- * Test that EventBus finds the correct subscribers.
- *
- * <p>This test must be outside the c.g.c.eventbus package to test correctly.
- *
- * @author Louis Wasserman
- */
-public class AnnotatedSubscriberFinderTests {
-
-  private static final Object EVENT = new Object();
-
-  abstract static class AbstractEventBusTest<H> extends TestCase {
-    abstract H createSubscriber();
-
-    private H subscriber;
-
-    H getSubscriber() {
-      return subscriber;
-    }
-
-    @Override
-    protected void setUp() throws Exception {
-      subscriber = createSubscriber();
-      EventBus bus = new EventBus();
-      bus.register(subscriber);
-      bus.post(EVENT);
-    }
-
-    @Override
-    protected void tearDown() throws Exception {
-      subscriber = null;
-    }
-  }
-
-  /*
-   * We break the tests up based on whether they are annotated or abstract in the superclass.
-   */
-  public static class BaseSubscriberFinderTest
-      extends AbstractEventBusTest<BaseSubscriberFinderTest.Subscriber> {
-    static class Subscriber {
-      final List<Object> nonSubscriberEvents = Lists.newArrayList();
-      final List<Object> subscriberEvents = Lists.newArrayList();
-
-      public void notASubscriber(Object o) {
-        nonSubscriberEvents.add(o);
-      }
-
-      @Subscribe
-      public void subscriber(Object o) {
-        subscriberEvents.add(o);
-      }
-    }
-
-    public void testNonSubscriber() {
-      assertThat(getSubscriber().nonSubscriberEvents).isEmpty();
-    }
-
-    public void testSubscriber() {
-      assertThat(getSubscriber().subscriberEvents).contains(EVENT);
-    }
-
-    @Override
-    Subscriber createSubscriber() {
-      return new Subscriber();
-    }
-  }
-
-  public static class AnnotatedAndAbstractInSuperclassTest
-      extends AbstractEventBusTest<AnnotatedAndAbstractInSuperclassTest.SubClass> {
-    abstract static class SuperClass {
-      @Subscribe
-      public abstract void overriddenAndAnnotatedInSubclass(Object o);
-
-      @Subscribe
-      public abstract void overriddenInSubclass(Object o);
-    }
-
-    static class SubClass extends SuperClass {
-      final List<Object> overriddenAndAnnotatedInSubclassEvents = Lists.newArrayList();
-      final List<Object> overriddenInSubclassEvents = Lists.newArrayList();
-
-      @Subscribe
-      @Override
-      public void overriddenAndAnnotatedInSubclass(Object o) {
-        overriddenAndAnnotatedInSubclassEvents.add(o);
-      }
-
-      @Override
-      public void overriddenInSubclass(Object o) {
-        overriddenInSubclassEvents.add(o);
-      }
-    }
-
-    public void testOverriddenAndAnnotatedInSubclass() {
-      assertThat(getSubscriber().overriddenAndAnnotatedInSubclassEvents).contains(EVENT);
-    }
-
-    public void testOverriddenNotAnnotatedInSubclass() {
-      assertThat(getSubscriber().overriddenInSubclassEvents).contains(EVENT);
-    }
-
-    @Override
-    SubClass createSubscriber() {
-      return new SubClass();
-    }
-  }
-
-  public static class AnnotatedNotAbstractInSuperclassTest
-      extends AbstractEventBusTest<AnnotatedNotAbstractInSuperclassTest.SubClass> {
-    static class SuperClass {
-      final List<Object> notOverriddenInSubclassEvents = Lists.newArrayList();
-      final List<Object> overriddenNotAnnotatedInSubclassEvents = Lists.newArrayList();
-      final List<Object> overriddenAndAnnotatedInSubclassEvents = Lists.newArrayList();
-      final List<Object> differentlyOverriddenNotAnnotatedInSubclassBadEvents =
-          Lists.newArrayList();
-      final List<Object> differentlyOverriddenAnnotatedInSubclassBadEvents = Lists.newArrayList();
-
-      @Subscribe
-      public void notOverriddenInSubclass(Object o) {
-        notOverriddenInSubclassEvents.add(o);
-      }
-
-      @Subscribe
-      public void overriddenNotAnnotatedInSubclass(Object o) {
-        overriddenNotAnnotatedInSubclassEvents.add(o);
-      }
-
-      @Subscribe
-      public void overriddenAndAnnotatedInSubclass(Object o) {
-        overriddenAndAnnotatedInSubclassEvents.add(o);
-      }
-
-      @Subscribe
-      public void differentlyOverriddenNotAnnotatedInSubclass(Object o) {
-        // the subclass overrides this and does *not* call super.dONAIS(o)
-        differentlyOverriddenNotAnnotatedInSubclassBadEvents.add(o);
-      }
-
-      @Subscribe
-      public void differentlyOverriddenAnnotatedInSubclass(Object o) {
-        // the subclass overrides this and does *not* call super.dOAIS(o)
-        differentlyOverriddenAnnotatedInSubclassBadEvents.add(o);
-      }
-    }
-
-    static class SubClass extends SuperClass {
-      final List<Object> differentlyOverriddenNotAnnotatedInSubclassGoodEvents =
-          Lists.newArrayList();
-      final List<Object> differentlyOverriddenAnnotatedInSubclassGoodEvents = Lists.newArrayList();
-
-      @Override
-      public void overriddenNotAnnotatedInSubclass(Object o) {
-        super.overriddenNotAnnotatedInSubclass(o);
-      }
-
-      @Subscribe
-      @Override
-      public void overriddenAndAnnotatedInSubclass(Object o) {
-        super.overriddenAndAnnotatedInSubclass(o);
-      }
-
-      @Override
-      public void differentlyOverriddenNotAnnotatedInSubclass(Object o) {
-        differentlyOverriddenNotAnnotatedInSubclassGoodEvents.add(o);
-      }
-
-      @Subscribe
-      @Override
-      public void differentlyOverriddenAnnotatedInSubclass(Object o) {
-        differentlyOverriddenAnnotatedInSubclassGoodEvents.add(o);
-      }
-    }
-
-    public void testNotOverriddenInSubclass() {
-      assertThat(getSubscriber().notOverriddenInSubclassEvents).contains(EVENT);
-    }
-
-    public void testOverriddenNotAnnotatedInSubclass() {
-      assertThat(getSubscriber().overriddenNotAnnotatedInSubclassEvents).contains(EVENT);
-    }
-
-    public void testDifferentlyOverriddenNotAnnotatedInSubclass() {
-      assertThat(getSubscriber().differentlyOverriddenNotAnnotatedInSubclassGoodEvents)
-          .contains(EVENT);
-      assertThat(getSubscriber().differentlyOverriddenNotAnnotatedInSubclassBadEvents).isEmpty();
-    }
-
-    public void testOverriddenAndAnnotatedInSubclass() {
-      assertThat(getSubscriber().overriddenAndAnnotatedInSubclassEvents).contains(EVENT);
-    }
-
-    public void testDifferentlyOverriddenAndAnnotatedInSubclass() {
-      assertThat(getSubscriber().differentlyOverriddenAnnotatedInSubclassGoodEvents)
-          .contains(EVENT);
-      assertThat(getSubscriber().differentlyOverriddenAnnotatedInSubclassBadEvents).isEmpty();
-    }
-
-    @Override
-    SubClass createSubscriber() {
-      return new SubClass();
-    }
-  }
-
-  public static class AbstractNotAnnotatedInSuperclassTest
-      extends AbstractEventBusTest<AbstractNotAnnotatedInSuperclassTest.SubClass> {
-    abstract static class SuperClass {
-      public abstract void overriddenInSubclassNowhereAnnotated(Object o);
-
-      public abstract void overriddenAndAnnotatedInSubclass(Object o);
-    }
-
-    static class SubClass extends SuperClass {
-      final List<Object> overriddenInSubclassNowhereAnnotatedEvents = Lists.newArrayList();
-      final List<Object> overriddenAndAnnotatedInSubclassEvents = Lists.newArrayList();
-
-      @Override
-      public void overriddenInSubclassNowhereAnnotated(Object o) {
-        overriddenInSubclassNowhereAnnotatedEvents.add(o);
-      }
-
-      @Subscribe
-      @Override
-      public void overriddenAndAnnotatedInSubclass(Object o) {
-        overriddenAndAnnotatedInSubclassEvents.add(o);
-      }
-    }
-
-    public void testOverriddenAndAnnotatedInSubclass() {
-      assertThat(getSubscriber().overriddenAndAnnotatedInSubclassEvents).contains(EVENT);
-    }
-
-    public void testOverriddenInSubclassNowhereAnnotated() {
-      assertThat(getSubscriber().overriddenInSubclassNowhereAnnotatedEvents).isEmpty();
-    }
-
-    @Override
-    SubClass createSubscriber() {
-      return new SubClass();
-    }
-  }
-
-  public static class NeitherAbstractNorAnnotatedInSuperclassTest
-      extends AbstractEventBusTest<NeitherAbstractNorAnnotatedInSuperclassTest.SubClass> {
-    static class SuperClass {
-      final List<Object> neitherOverriddenNorAnnotatedEvents = Lists.newArrayList();
-      final List<Object> overriddenInSubclassNowhereAnnotatedEvents = Lists.newArrayList();
-      final List<Object> overriddenAndAnnotatedInSubclassEvents = Lists.newArrayList();
-
-      public void neitherOverriddenNorAnnotated(Object o) {
-        neitherOverriddenNorAnnotatedEvents.add(o);
-      }
-
-      public void overriddenInSubclassNowhereAnnotated(Object o) {
-        overriddenInSubclassNowhereAnnotatedEvents.add(o);
-      }
-
-      public void overriddenAndAnnotatedInSubclass(Object o) {
-        overriddenAndAnnotatedInSubclassEvents.add(o);
-      }
-    }
-
-    static class SubClass extends SuperClass {
-      @Override
-      public void overriddenInSubclassNowhereAnnotated(Object o) {
-        super.overriddenInSubclassNowhereAnnotated(o);
-      }
-
-      @Subscribe
-      @Override
-      public void overriddenAndAnnotatedInSubclass(Object o) {
-        super.overriddenAndAnnotatedInSubclass(o);
-      }
-    }
-
-    public void testNeitherOverriddenNorAnnotated() {
-      assertThat(getSubscriber().neitherOverriddenNorAnnotatedEvents).isEmpty();
-    }
-
-    public void testOverriddenInSubclassNowhereAnnotated() {
-      assertThat(getSubscriber().overriddenInSubclassNowhereAnnotatedEvents).isEmpty();
-    }
-
-    public void testOverriddenAndAnnotatedInSubclass() {
-      assertThat(getSubscriber().overriddenAndAnnotatedInSubclassEvents).contains(EVENT);
-    }
-
-    @Override
-    SubClass createSubscriber() {
-      return new SubClass();
-    }
-  }
-
-  public static class DeepInterfaceTest
-      extends AbstractEventBusTest<DeepInterfaceTest.SubscriberClass> {
-    interface Interface1 {
-      @Subscribe
-      void annotatedIn1(Object o);
-
-      @Subscribe
-      void annotatedIn1And2(Object o);
-
-      @Subscribe
-      void annotatedIn1And2AndClass(Object o);
-
-      void declaredIn1AnnotatedIn2(Object o);
-
-      void declaredIn1AnnotatedInClass(Object o);
-
-      void nowhereAnnotated(Object o);
-    }
-
-    interface Interface2 extends Interface1 {
-      @Override
-      @Subscribe
-      void declaredIn1AnnotatedIn2(Object o);
-
-      @Override
-      @Subscribe
-      void annotatedIn1And2(Object o);
-
-      @Override
-      @Subscribe
-      void annotatedIn1And2AndClass(Object o);
-
-      void declaredIn2AnnotatedInClass(Object o);
-
-      @Subscribe
-      void annotatedIn2(Object o);
-    }
-
-    static class SubscriberClass implements Interface2 {
-      final List<Object> annotatedIn1Events = Lists.newArrayList();
-      final List<Object> annotatedIn1And2Events = Lists.newArrayList();
-      final List<Object> annotatedIn1And2AndClassEvents = Lists.newArrayList();
-      final List<Object> declaredIn1AnnotatedIn2Events = Lists.newArrayList();
-      final List<Object> declaredIn1AnnotatedInClassEvents = Lists.newArrayList();
-      final List<Object> declaredIn2AnnotatedInClassEvents = Lists.newArrayList();
-      final List<Object> annotatedIn2Events = Lists.newArrayList();
-      final List<Object> nowhereAnnotatedEvents = Lists.newArrayList();
-
-      @Override
-      public void annotatedIn1(Object o) {
-        annotatedIn1Events.add(o);
-      }
-
-      @Subscribe
-      @Override
-      public void declaredIn1AnnotatedInClass(Object o) {
-        declaredIn1AnnotatedInClassEvents.add(o);
-      }
-
-      @Override
-      public void declaredIn1AnnotatedIn2(Object o) {
-        declaredIn1AnnotatedIn2Events.add(o);
-      }
-
-      @Override
-      public void annotatedIn1And2(Object o) {
-        annotatedIn1And2Events.add(o);
-      }
-
-      @Subscribe
-      @Override
-      public void annotatedIn1And2AndClass(Object o) {
-        annotatedIn1And2AndClassEvents.add(o);
-      }
-
-      @Subscribe
-      @Override
-      public void declaredIn2AnnotatedInClass(Object o) {
-        declaredIn2AnnotatedInClassEvents.add(o);
-      }
-
-      @Override
-      public void annotatedIn2(Object o) {
-        annotatedIn2Events.add(o);
-      }
-
-      @Override
-      public void nowhereAnnotated(Object o) {
-        nowhereAnnotatedEvents.add(o);
-      }
-    }
-
-    public void testAnnotatedIn1() {
-      assertThat(getSubscriber().annotatedIn1Events).contains(EVENT);
-    }
-
-    public void testAnnotatedIn2() {
-      assertThat(getSubscriber().annotatedIn2Events).contains(EVENT);
-    }
-
-    public void testAnnotatedIn1And2() {
-      assertThat(getSubscriber().annotatedIn1And2Events).contains(EVENT);
-    }
-
-    public void testAnnotatedIn1And2AndClass() {
-      assertThat(getSubscriber().annotatedIn1And2AndClassEvents).contains(EVENT);
-    }
-
-    public void testDeclaredIn1AnnotatedIn2() {
-      assertThat(getSubscriber().declaredIn1AnnotatedIn2Events).contains(EVENT);
-    }
-
-    public void testDeclaredIn1AnnotatedInClass() {
-      assertThat(getSubscriber().declaredIn1AnnotatedInClassEvents).contains(EVENT);
-    }
-
-    public void testDeclaredIn2AnnotatedInClass() {
-      assertThat(getSubscriber().declaredIn2AnnotatedInClassEvents).contains(EVENT);
-    }
-
-    public void testNowhereAnnotated() {
-      assertThat(getSubscriber().nowhereAnnotatedEvents).isEmpty();
-    }
-
-    @Override
-    SubscriberClass createSubscriber() {
-      return new SubscriberClass();
-    }
-  }
-}
diff --git a/android/guava-tests/test/com/google/common/eventbus/outside/BaseSubscriberFinderTest.java b/android/guava-tests/test/com/google/common/eventbus/outside/BaseSubscriberFinderTest.java
new file mode 100644
index 000000000000..461fb795b07d
--- /dev/null
+++ b/android/guava-tests/test/com/google/common/eventbus/outside/BaseSubscriberFinderTest.java
@@ -0,0 +1,53 @@
+/*
+ * Copyright (C) 2012 The Guava Authors
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package com.google.common.eventbus.outside;
+
+import static com.google.common.truth.Truth.assertThat;
+
+import com.google.common.collect.Lists;
+import com.google.common.eventbus.Subscribe;
+import com.google.common.eventbus.outside.BaseSubscriberFinderTest.Subscriber;
+import java.util.List;
+
+public class BaseSubscriberFinderTest extends AbstractEventBusTest<Subscriber> {
+  static class Subscriber {
+    final List<Object> nonSubscriberEvents = Lists.newArrayList();
+    final List<Object> subscriberEvents = Lists.newArrayList();
+
+    public void notASubscriber(Object o) {
+      nonSubscriberEvents.add(o);
+    }
+
+    @Subscribe
+    public void subscriber(Object o) {
+      subscriberEvents.add(o);
+    }
+  }
+
+  public void testNonSubscriber() {
+    assertThat(getSubscriber().nonSubscriberEvents).isEmpty();
+  }
+
+  public void testSubscriber() {
+    assertThat(getSubscriber().subscriberEvents).contains(EVENT);
+  }
+
+  @Override
+  Subscriber createSubscriber() {
+    return new Subscriber();
+  }
+}
diff --git a/android/guava-tests/test/com/google/common/eventbus/outside/DeepInterfaceTest.java b/android/guava-tests/test/com/google/common/eventbus/outside/DeepInterfaceTest.java
new file mode 100644
index 000000000000..4fefbc12ab15
--- /dev/null
+++ b/android/guava-tests/test/com/google/common/eventbus/outside/DeepInterfaceTest.java
@@ -0,0 +1,153 @@
+/*
+ * Copyright (C) 2012 The Guava Authors
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package com.google.common.eventbus.outside;
+
+import static com.google.common.truth.Truth.assertThat;
+
+import com.google.common.collect.Lists;
+import com.google.common.eventbus.Subscribe;
+import com.google.common.eventbus.outside.DeepInterfaceTest.SubscriberClass;
+import java.util.List;
+
+public class DeepInterfaceTest extends AbstractEventBusTest<SubscriberClass> {
+  interface Interface1 {
+    @Subscribe
+    void annotatedIn1(Object o);
+
+    @Subscribe
+    void annotatedIn1And2(Object o);
+
+    @Subscribe
+    void annotatedIn1And2AndClass(Object o);
+
+    void declaredIn1AnnotatedIn2(Object o);
+
+    void declaredIn1AnnotatedInClass(Object o);
+
+    void nowhereAnnotated(Object o);
+  }
+
+  interface Interface2 extends Interface1 {
+    @Override
+    @Subscribe
+    void declaredIn1AnnotatedIn2(Object o);
+
+    @Override
+    @Subscribe
+    void annotatedIn1And2(Object o);
+
+    @Override
+    @Subscribe
+    void annotatedIn1And2AndClass(Object o);
+
+    void declaredIn2AnnotatedInClass(Object o);
+
+    @Subscribe
+    void annotatedIn2(Object o);
+  }
+
+  static class SubscriberClass implements Interface2 {
+    final List<Object> annotatedIn1Events = Lists.newArrayList();
+    final List<Object> annotatedIn1And2Events = Lists.newArrayList();
+    final List<Object> annotatedIn1And2AndClassEvents = Lists.newArrayList();
+    final List<Object> declaredIn1AnnotatedIn2Events = Lists.newArrayList();
+    final List<Object> declaredIn1AnnotatedInClassEvents = Lists.newArrayList();
+    final List<Object> declaredIn2AnnotatedInClassEvents = Lists.newArrayList();
+    final List<Object> annotatedIn2Events = Lists.newArrayList();
+    final List<Object> nowhereAnnotatedEvents = Lists.newArrayList();
+
+    @Override
+    public void annotatedIn1(Object o) {
+      annotatedIn1Events.add(o);
+    }
+
+    @Subscribe
+    @Override
+    public void declaredIn1AnnotatedInClass(Object o) {
+      declaredIn1AnnotatedInClassEvents.add(o);
+    }
+
+    @Override
+    public void declaredIn1AnnotatedIn2(Object o) {
+      declaredIn1AnnotatedIn2Events.add(o);
+    }
+
+    @Override
+    public void annotatedIn1And2(Object o) {
+      annotatedIn1And2Events.add(o);
+    }
+
+    @Subscribe
+    @Override
+    public void annotatedIn1And2AndClass(Object o) {
+      annotatedIn1And2AndClassEvents.add(o);
+    }
+
+    @Subscribe
+    @Override
+    public void declaredIn2AnnotatedInClass(Object o) {
+      declaredIn2AnnotatedInClassEvents.add(o);
+    }
+
+    @Override
+    public void annotatedIn2(Object o) {
+      annotatedIn2Events.add(o);
+    }
+
+    @Override
+    public void nowhereAnnotated(Object o) {
+      nowhereAnnotatedEvents.add(o);
+    }
+  }
+
+  public void testAnnotatedIn1() {
+    assertThat(getSubscriber().annotatedIn1Events).contains(EVENT);
+  }
+
+  public void testAnnotatedIn2() {
+    assertThat(getSubscriber().annotatedIn2Events).contains(EVENT);
+  }
+
+  public void testAnnotatedIn1And2() {
+    assertThat(getSubscriber().annotatedIn1And2Events).contains(EVENT);
+  }
+
+  public void testAnnotatedIn1And2AndClass() {
+    assertThat(getSubscriber().annotatedIn1And2AndClassEvents).contains(EVENT);
+  }
+
+  public void testDeclaredIn1AnnotatedIn2() {
+    assertThat(getSubscriber().declaredIn1AnnotatedIn2Events).contains(EVENT);
+  }
+
+  public void testDeclaredIn1AnnotatedInClass() {
+    assertThat(getSubscriber().declaredIn1AnnotatedInClassEvents).contains(EVENT);
+  }
+
+  public void testDeclaredIn2AnnotatedInClass() {
+    assertThat(getSubscriber().declaredIn2AnnotatedInClassEvents).contains(EVENT);
+  }
+
+  public void testNowhereAnnotated() {
+    assertThat(getSubscriber().nowhereAnnotatedEvents).isEmpty();
+  }
+
+  @Override
+  SubscriberClass createSubscriber() {
+    return new SubscriberClass();
+  }
+}
diff --git a/android/guava-tests/test/com/google/common/eventbus/outside/NeitherAbstractNorAnnotatedInSuperclassTest.java b/android/guava-tests/test/com/google/common/eventbus/outside/NeitherAbstractNorAnnotatedInSuperclassTest.java
new file mode 100644
index 000000000000..a2aca555b499
--- /dev/null
+++ b/android/guava-tests/test/com/google/common/eventbus/outside/NeitherAbstractNorAnnotatedInSuperclassTest.java
@@ -0,0 +1,74 @@
+/*
+ * Copyright (C) 2012 The Guava Authors
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package com.google.common.eventbus.outside;
+
+import static com.google.common.truth.Truth.assertThat;
+
+import com.google.common.collect.Lists;
+import com.google.common.eventbus.Subscribe;
+import com.google.common.eventbus.outside.NeitherAbstractNorAnnotatedInSuperclassTest.SubClass;
+import java.util.List;
+
+public class NeitherAbstractNorAnnotatedInSuperclassTest extends AbstractEventBusTest<SubClass> {
+  static class SuperClass {
+    final List<Object> neitherOverriddenNorAnnotatedEvents = Lists.newArrayList();
+    final List<Object> overriddenInSubclassNowhereAnnotatedEvents = Lists.newArrayList();
+    final List<Object> overriddenAndAnnotatedInSubclassEvents = Lists.newArrayList();
+
+    public void neitherOverriddenNorAnnotated(Object o) {
+      neitherOverriddenNorAnnotatedEvents.add(o);
+    }
+
+    public void overriddenInSubclassNowhereAnnotated(Object o) {
+      overriddenInSubclassNowhereAnnotatedEvents.add(o);
+    }
+
+    public void overriddenAndAnnotatedInSubclass(Object o) {
+      overriddenAndAnnotatedInSubclassEvents.add(o);
+    }
+  }
+
+  static class SubClass extends SuperClass {
+    @Override
+    public void overriddenInSubclassNowhereAnnotated(Object o) {
+      super.overriddenInSubclassNowhereAnnotated(o);
+    }
+
+    @Subscribe
+    @Override
+    public void overriddenAndAnnotatedInSubclass(Object o) {
+      super.overriddenAndAnnotatedInSubclass(o);
+    }
+  }
+
+  public void testNeitherOverriddenNorAnnotated() {
+    assertThat(getSubscriber().neitherOverriddenNorAnnotatedEvents).isEmpty();
+  }
+
+  public void testOverriddenInSubclassNowhereAnnotated() {
+    assertThat(getSubscriber().overriddenInSubclassNowhereAnnotatedEvents).isEmpty();
+  }
+
+  public void testOverriddenAndAnnotatedInSubclass() {
+    assertThat(getSubscriber().overriddenAndAnnotatedInSubclassEvents).contains(EVENT);
+  }
+
+  @Override
+  SubClass createSubscriber() {
+    return new SubClass();
+  }
+}
diff --git a/android/guava-tests/test/com/google/common/graph/MapCacheTest.java b/android/guava-tests/test/com/google/common/graph/MapCacheTest.java
index f66b19b7d985..f04f010c84c9 100644
--- a/android/guava-tests/test/com/google/common/graph/MapCacheTest.java
+++ b/android/guava-tests/test/com/google/common/graph/MapCacheTest.java
@@ -90,25 +90,4 @@ public void testRemoveEqualKeyWithDifferentReference() {
     assertThat(mapCache.remove(fooReference2)).isEqualTo("bar");
     assertThat(mapCache.get(fooReference1)).isNull();
   }
-
-  @Test
-  public void testHandleNulls() {
-    mapCache.put("foo", "bar");
-    mapCache.put("non-null key", null);
-    mapCache.put(null, "non-null value");
-
-    assertThat(mapCache.get("foo")).isEqualTo("bar");
-    assertThat(mapCache.get("non-null key")).isNull();
-    assertThat(mapCache.get(null)).isEqualTo("non-null value");
-
-    assertThat(mapCache.containsKey("foo")).isTrue();
-    assertThat(mapCache.containsKey("bar")).isFalse();
-    assertThat(mapCache.containsKey("non-null key")).isTrue();
-    assertThat(mapCache.containsKey(null)).isTrue();
-
-    // Test again - in reverse order.
-    assertThat(mapCache.get(null)).isEqualTo("non-null value");
-    assertThat(mapCache.get("non-null key")).isNull();
-    assertThat(mapCache.get("foo")).isEqualTo("bar");
-  }
 }
diff --git a/android/guava-tests/test/com/google/common/hash/BloomFilterTest.java b/android/guava-tests/test/com/google/common/hash/BloomFilterTest.java
index f69b57853374..d99be0902708 100644
--- a/android/guava-tests/test/com/google/common/hash/BloomFilterTest.java
+++ b/android/guava-tests/test/com/google/common/hash/BloomFilterTest.java
@@ -36,8 +36,8 @@
 import java.util.List;
 import java.util.Random;
 import java.util.concurrent.TimeUnit;
+import javax.annotation.CheckForNull;
 import junit.framework.TestCase;
-import org.checkerframework.checker.nullness.compatqual.NullableDecl;
 
 /**
  * Tests for SimpleGenericBloomFilter and derived BloomFilter views.
@@ -408,7 +408,7 @@ public void funnel(Long value, PrimitiveSink into) {
     }
 
     @Override
-    public boolean equals(@NullableDecl Object object) {
+    public boolean equals(@CheckForNull Object object) {
       return (object instanceof CustomFunnel);
     }
 
@@ -506,7 +506,10 @@ public void testCustomSerialization() throws Exception {
     ByteArrayOutputStream out = new ByteArrayOutputStream();
     bf.writeTo(out);
 
-    assertEquals(bf, BloomFilter.readFrom(new ByteArrayInputStream(out.toByteArray()), funnel));
+    BloomFilter<byte[]> read =
+        BloomFilter.readFrom(new ByteArrayInputStream(out.toByteArray()), funnel);
+    assertThat(read).isEqualTo(bf);
+    assertThat(read.expectedFpp()).isGreaterThan(0);
   }
 
   /**
diff --git a/android/guava-tests/test/com/google/common/hash/Fingerprint2011Test.java b/android/guava-tests/test/com/google/common/hash/Fingerprint2011Test.java
new file mode 100644
index 000000000000..effa63291bf1
--- /dev/null
+++ b/android/guava-tests/test/com/google/common/hash/Fingerprint2011Test.java
@@ -0,0 +1,233 @@
+// Copyright 2011 Google Inc. All Rights Reserved.
+
+package com.google.common.hash;
+
+import static com.google.common.base.Charsets.ISO_8859_1;
+import static com.google.common.base.Charsets.UTF_8;
+import static com.google.common.truth.Truth.assertThat;
+
+import com.google.common.base.Strings;
+import com.google.common.collect.ImmutableSortedMap;
+import com.google.common.collect.Ordering;
+import com.google.common.primitives.UnsignedLong;
+import java.util.Arrays;
+import junit.framework.TestCase;
+
+/**
+ * Unit test for Fingerprint2011.
+ *
+ * @author kylemaddison@google.com (Kyle Maddison)
+ */
+public class Fingerprint2011Test extends TestCase {
+
+  // Length of the sample string to produce
+  private static final int MAX_BYTES = 1000;
+
+  // Map from sample string lengths to the fingerprint
+  private static final ImmutableSortedMap<Integer, Long> LENGTH_FINGERPRINTS =
+      new ImmutableSortedMap.Builder<Integer, Long>(Ordering.natural())
+          .put(1000, 0x433109b33e13e6edL)
+          .put(800, 0x5f2f123bfc815f81L)
+          .put(640, 0x6396fc6a67293cf4L)
+          .put(512, 0x45c01b4934ddbbbeL)
+          .put(409, 0xfcd19b617551db45L)
+          .put(327, 0x4eee69e12854871eL)
+          .put(261, 0xab753446a3bbd532L)
+          .put(208, 0x54242fe06a291c3fL)
+          .put(166, 0x4f7acff7703a635bL)
+          .put(132, 0xa784bd0a1f22cc7fL)
+          .put(105, 0xf19118e187456638L)
+          .put(84, 0x3e2e58f9196abfe5L)
+          .put(67, 0xd38ae3dec0107aeaL)
+          .put(53, 0xea3033885868e10eL)
+          .put(42, 0x1394a146d0d7e04bL)
+          .put(33, 0x9962499315d2e8daL)
+          .put(26, 0x0849f5cfa85489b5L)
+          .put(20, 0x83b395ff19bf2171L)
+          .put(16, 0x9d33dd141bd55d9aL)
+          .put(12, 0x196248eb0b02466aL)
+          .put(9, 0x1cf73a50ff120336L)
+          .put(7, 0xb451c339457dbf51L)
+          .put(5, 0x681982c5e7b74064L)
+          .put(4, 0xc5ce47450ca6c021L)
+          .put(3, 0x9fcc3c3fde4d5ff7L)
+          .put(2, 0x090966a836e5fa4bL)
+          .put(1, 0x8199675ecaa6fe64L)
+          .put(0, 0x23ad7c904aa665e3L)
+          .build();
+  private static final HashFunction HASH_FN = Hashing.fingerprint2011();
+
+  // If this test fails, all bets are off
+  public void testReallySimpleFingerprints() {
+    assertEquals(8473225671271759044L, fingerprint("test".getBytes(UTF_8)));
+    // 32 characters long
+    assertEquals(7345148637025587076L, fingerprint(Strings.repeat("test", 8).getBytes(UTF_8)));
+    // 256 characters long
+    assertEquals(4904844928629814570L, fingerprint(Strings.repeat("test", 64).getBytes(UTF_8)));
+  }
+
+  public void testStringsConsistency() {
+    for (String s : Arrays.asList("", "some", "test", "strings", "to", "try")) {
+      assertEquals(HASH_FN.newHasher().putUnencodedChars(s).hash(), HASH_FN.hashUnencodedChars(s));
+    }
+  }
+
+  public void testUtf8() {
+    char[] charsA = new char[128];
+    char[] charsB = new char[128];
+
+    for (int i = 0; i < charsA.length; i++) {
+      if (i < 100) {
+        charsA[i] = 'a';
+        charsB[i] = 'a';
+      } else {
+        // Both two-byte characters, but must be different
+        charsA[i] = (char) (0x0180 + i);
+        charsB[i] = (char) (0x0280 + i);
+      }
+    }
+
+    String stringA = new String(charsA);
+    String stringB = new String(charsB);
+    assertThat(stringA).isNotEqualTo(stringB);
+    assertThat(HASH_FN.hashUnencodedChars(stringA))
+        .isNotEqualTo(HASH_FN.hashUnencodedChars(stringB));
+    assertThat(fingerprint(stringA.getBytes(UTF_8)))
+        .isNotEqualTo(fingerprint(stringB.getBytes(UTF_8)));
+
+    // ISO 8859-1 only has 0-255 (ubyte) representation so throws away UTF-8 characters
+    // greater than 127 (ie with their top bit set).
+    // Don't attempt to do this in real code.
+    assertEquals(
+        fingerprint(stringA.getBytes(ISO_8859_1)), fingerprint(stringB.getBytes(ISO_8859_1)));
+  }
+
+  public void testMumurHash64() {
+    byte[] bytes = "test".getBytes(UTF_8);
+    assertEquals(
+        1618900948208871284L, Fingerprint2011.murmurHash64WithSeed(bytes, 0, bytes.length, 1));
+
+    bytes = "test test test".getBytes(UTF_8);
+    assertEquals(
+        UnsignedLong.valueOf("12313169684067793560").longValue(),
+        Fingerprint2011.murmurHash64WithSeed(bytes, 0, bytes.length, 1));
+  }
+
+  public void testPutNonChars() {
+    Hasher hasher = HASH_FN.newHasher();
+    // Expected data is 0x0100010100000000
+    hasher
+        .putBoolean(true)
+        .putBoolean(true)
+        .putBoolean(false)
+        .putBoolean(true)
+        .putBoolean(false)
+        .putBoolean(false)
+        .putBoolean(false)
+        .putBoolean(false);
+    final long hashCode = hasher.hash().asLong();
+
+    hasher = HASH_FN.newHasher();
+    hasher
+        .putByte((byte) 0x01)
+        .putByte((byte) 0x01)
+        .putByte((byte) 0x00)
+        .putByte((byte) 0x01)
+        .putByte((byte) 0x00)
+        .putByte((byte) 0x00)
+        .putByte((byte) 0x00)
+        .putByte((byte) 0x00);
+    assertEquals(hashCode, hasher.hash().asLong());
+
+    hasher = HASH_FN.newHasher();
+    hasher
+        .putChar((char) 0x0101)
+        .putChar((char) 0x0100)
+        .putChar((char) 0x0000)
+        .putChar((char) 0x0000);
+    assertEquals(hashCode, hasher.hash().asLong());
+
+    hasher = HASH_FN.newHasher();
+    hasher.putBytes(new byte[] {0x01, 0x01, 0x00, 0x01, 0x00, 0x00, 0x00, 0x00});
+    assertEquals(hashCode, hasher.hash().asLong());
+
+    hasher = HASH_FN.newHasher();
+    hasher.putLong(0x0000000001000101L);
+    assertEquals(hashCode, hasher.hash().asLong());
+
+    hasher = HASH_FN.newHasher();
+    hasher
+        .putShort((short) 0x0101)
+        .putShort((short) 0x0100)
+        .putShort((short) 0x0000)
+        .putShort((short) 0x0000);
+    assertEquals(hashCode, hasher.hash().asLong());
+  }
+
+  public void testHashFloatIsStable() {
+    // This is about the best we can do for floating-point
+    Hasher hasher = HASH_FN.newHasher();
+    hasher.putFloat(0x01000101f).putFloat(0f);
+    assertEquals(0x96a4f8cc6ecbf16L, hasher.hash().asLong());
+
+    hasher = HASH_FN.newHasher();
+    hasher.putDouble(0x0000000001000101d);
+    assertEquals(0xcf54171253fdc198L, hasher.hash().asLong());
+  }
+
+  /** Convenience method to compute a fingerprint on a full bytes array. */
+  private static long fingerprint(byte[] bytes) {
+    return fingerprint(bytes, bytes.length);
+  }
+
+  /** Convenience method to compute a fingerprint on a subset of a byte array. */
+  private static long fingerprint(byte[] bytes, int length) {
+    return HASH_FN.hashBytes(bytes, 0, length).asLong();
+  }
+
+  /**
+   * Tests that the Java port of Fingerprint2011 provides the same results on buffers up to 800
+   * bytes long as the original implementation in C++. See http://cl/106539598
+   */
+  public void testMultipleLengths() {
+    int iterations = 800;
+    byte[] buf = new byte[iterations * 4];
+    int bufLen = 0;
+    long h = 0;
+    for (int i = 0; i < iterations; ++i) {
+      h ^= fingerprint(buf, i);
+      h = remix(h);
+      buf[bufLen++] = getChar(h);
+
+      h ^= fingerprint(buf, i * i % bufLen);
+      h = remix(h);
+      buf[bufLen++] = getChar(h);
+
+      h ^= fingerprint(buf, i * i * i % bufLen);
+      h = remix(h);
+      buf[bufLen++] = getChar(h);
+
+      h ^= fingerprint(buf, bufLen);
+      h = remix(h);
+      buf[bufLen++] = getChar(h);
+
+      int x0 = buf[bufLen - 1] & 0xff;
+      int x1 = buf[bufLen - 2] & 0xff;
+      int x2 = buf[bufLen - 3] & 0xff;
+      int x3 = buf[bufLen / 2] & 0xff;
+      buf[((x0 << 16) + (x1 << 8) + x2) % bufLen] ^= x3;
+      buf[((x1 << 16) + (x2 << 8) + x3) % bufLen] ^= i % 256;
+    }
+    assertEquals(0xeaa3b1c985261632L, h);
+  }
+
+  private static long remix(long h) {
+    h ^= h >>> 41;
+    h *= 949921979;
+    return h;
+  }
+
+  private static byte getChar(long h) {
+    return (byte) ('a' + ((h & 0xfffff) % 26));
+  }
+}
diff --git a/android/guava-tests/test/com/google/common/hash/HashFunctionEnum.java b/android/guava-tests/test/com/google/common/hash/HashFunctionEnum.java
index 3a98fede9540..34717477e645 100644
--- a/android/guava-tests/test/com/google/common/hash/HashFunctionEnum.java
+++ b/android/guava-tests/test/com/google/common/hash/HashFunctionEnum.java
@@ -32,6 +32,7 @@ enum HashFunctionEnum {
   MD5(Hashing.md5()),
   MURMUR3_128(Hashing.murmur3_128()),
   MURMUR3_32(Hashing.murmur3_32()),
+  MURMUR3_32_FIXED(Hashing.murmur3_32_fixed()),
   SHA1(Hashing.sha1()),
   SHA256(Hashing.sha256()),
   SHA384(Hashing.sha384()),
diff --git a/android/guava-tests/test/com/google/common/hash/HashTestUtils.java b/android/guava-tests/test/com/google/common/hash/HashTestUtils.java
index 8dfbdb0cdf03..9e9944b5abfb 100644
--- a/android/guava-tests/test/com/google/common/hash/HashTestUtils.java
+++ b/android/guava-tests/test/com/google/common/hash/HashTestUtils.java
@@ -195,8 +195,8 @@ void performAction(Random random, Iterable<? extends PrimitiveSink> sinks) {
         int limit = pos + random.nextInt(value.length - pos + 1);
         for (PrimitiveSink sink : sinks) {
           ByteBuffer buffer = ByteBuffer.wrap(value);
-          buffer.position(pos);
-          buffer.limit(limit);
+          Java8Compatibility.position(buffer, pos);
+          Java8Compatibility.limit(buffer, limit);
           sink.putBytes(buffer);
           assertEquals(limit, buffer.limit());
           assertEquals(limit, buffer.position());
diff --git a/android/guava-tests/test/com/google/common/hash/HashingTest.java b/android/guava-tests/test/com/google/common/hash/HashingTest.java
index dc50299ea00f..aff5c254fac2 100644
--- a/android/guava-tests/test/com/google/common/hash/HashingTest.java
+++ b/android/guava-tests/test/com/google/common/hash/HashingTest.java
@@ -125,6 +125,15 @@ public void testSipHash24() {
         Hashing.sipHash24().toString());
   }
 
+  public void testFingerprint2011() {
+    HashTestUtils.check2BitAvalanche(Hashing.fingerprint2011(), 100, 0.4);
+    HashTestUtils.checkAvalanche(Hashing.fingerprint2011(), 100, 0.4);
+    HashTestUtils.checkNo2BitCharacteristics(Hashing.fingerprint2011());
+    HashTestUtils.checkNoFunnels(Hashing.fingerprint2011());
+    HashTestUtils.assertInvariants(Hashing.fingerprint2011());
+    assertEquals("Hashing.fingerprint2011()", Hashing.fingerprint2011().toString());
+  }
+
   @AndroidIncompatible // slow TODO(cpovirk): Maybe just reduce iterations under Android.
   public void testGoodFastHash() {
     for (int i = 1; i < 200; i += 17) {
@@ -146,7 +155,7 @@ public void testGoodFastHash32() {
   // goodFastHash(128) uses Murmur3_128. Use the same epsilon bounds.
   public void testGoodFastHash128() {
     HashTestUtils.check2BitAvalanche(Hashing.goodFastHash(128), 250, 0.20);
-    HashTestUtils.checkAvalanche(Hashing.goodFastHash(128), 250, 0.17);
+    HashTestUtils.checkAvalanche(Hashing.goodFastHash(128), 500, 0.17);
     HashTestUtils.checkNo2BitCharacteristics(Hashing.goodFastHash(128));
     HashTestUtils.checkNoFunnels(Hashing.goodFastHash(128));
     HashTestUtils.assertInvariants(Hashing.goodFastHash(128));
@@ -155,7 +164,7 @@ public void testGoodFastHash128() {
   // goodFastHash(256) uses Murmur3_128. Use the same epsilon bounds.
   public void testGoodFastHash256() {
     HashTestUtils.check2BitAvalanche(Hashing.goodFastHash(256), 250, 0.20);
-    HashTestUtils.checkAvalanche(Hashing.goodFastHash(256), 250, 0.17);
+    HashTestUtils.checkAvalanche(Hashing.goodFastHash(256), 500, 0.17);
     HashTestUtils.checkNo2BitCharacteristics(Hashing.goodFastHash(256));
     HashTestUtils.checkNoFunnels(Hashing.goodFastHash(256));
     HashTestUtils.assertInvariants(Hashing.goodFastHash(256));
@@ -432,6 +441,9 @@ public void testHashIntVsForLoop() {
           .put(Hashing.murmur3_32(), EMPTY_STRING, "00000000")
           .put(Hashing.murmur3_32(), TQBFJOTLD, "23f74f2e")
           .put(Hashing.murmur3_32(), TQBFJOTLDP, "fc8bc4d5")
+          .put(Hashing.murmur3_32_fixed(), EMPTY_STRING, "00000000")
+          .put(Hashing.murmur3_32_fixed(), TQBFJOTLD, "23f74f2e")
+          .put(Hashing.murmur3_32_fixed(), TQBFJOTLDP, "fc8bc4d5")
           .put(Hashing.sha1(), EMPTY_STRING, "da39a3ee5e6b4b0d3255bfef95601890afd80709")
           .put(Hashing.sha1(), TQBFJOTLD, "2fd4e1c67a2d28fced849ee1bb76e7391b93eb12")
           .put(Hashing.sha1(), TQBFJOTLDP, "408d94384216f890ff7a0c3528e8bed1e0b01621")
@@ -489,6 +501,9 @@ public void testHashIntVsForLoop() {
           .put(Hashing.farmHashFingerprint64(), EMPTY_STRING, "4f40902f3b6ae19a")
           .put(Hashing.farmHashFingerprint64(), TQBFJOTLD, "34511b3bf383beab")
           .put(Hashing.farmHashFingerprint64(), TQBFJOTLDP, "737d7e5f8660653e")
+          .put(Hashing.fingerprint2011(), EMPTY_STRING, "e365a64a907cad23")
+          .put(Hashing.fingerprint2011(), TQBFJOTLD, "c9688c84e813b089")
+          .put(Hashing.fingerprint2011(), TQBFJOTLDP, "a714d70f1d569cd0")
           .build();
 
   public void testAllHashFunctionsHaveKnownHashes() throws Exception {
diff --git a/android/guava-tests/test/com/google/common/hash/Murmur3Hash32Test.java b/android/guava-tests/test/com/google/common/hash/Murmur3Hash32Test.java
index de86e4bbd86b..181b2a7bb071 100644
--- a/android/guava-tests/test/com/google/common/hash/Murmur3Hash32Test.java
+++ b/android/guava-tests/test/com/google/common/hash/Murmur3Hash32Test.java
@@ -17,9 +17,11 @@
 package com.google.common.hash;
 
 import static com.google.common.hash.Hashing.murmur3_32;
+import static com.google.common.hash.Hashing.murmur3_32_fixed;
 
 import com.google.common.base.Charsets;
 import com.google.common.hash.HashTestUtils.HashFn;
+import java.nio.charset.Charset;
 import java.util.Random;
 import junit.framework.TestCase;
 
@@ -51,16 +53,53 @@ public void testKnownStringInputs() {
         -528633700, murmur3_32().hashUnencodedChars("The quick brown fox jumps over the lazy dog"));
   }
 
-  public void testKnownUtf8StringInputs() {
-    assertHash(0, murmur3_32().hashString("", Charsets.UTF_8));
-    assertHash(0xcfbda5d1, murmur3_32().hashString("k", Charsets.UTF_8));
-    assertHash(0xa167dbf3, murmur3_32().hashString("hell", Charsets.UTF_8));
-    assertHash(0x248bfa47, murmur3_32().hashString("hello", Charsets.UTF_8));
-    assertHash(0x3d41b97c, murmur3_32().hashString("http://www.google.com/", Charsets.UTF_8));
-    assertHash(
-        0x2e4ff723,
-        murmur3_32().hashString("The quick brown fox jumps over the lazy dog", Charsets.UTF_8));
-    assertHash(0xfc5ba834, murmur3_32().hashString("毎月１日,毎週月曜日", Charsets.UTF_8));
+  @SuppressWarnings("deprecation")
+  public void testKnownEncodedStringInputs() {
+    assertStringHash(0, "", Charsets.UTF_8);
+    assertStringHash(0xcfbda5d1, "k", Charsets.UTF_8);
+    assertStringHash(0xa167dbf3, "hell", Charsets.UTF_8);
+    assertStringHash(0x248bfa47, "hello", Charsets.UTF_8);
+    assertStringHash(0x3d41b97c, "http://www.google.com/", Charsets.UTF_8);
+    assertStringHash(0x2e4ff723, "The quick brown fox jumps over the lazy dog", Charsets.UTF_8);
+    assertStringHash(0xb5a4be05, "ABCDefGHI\u0799", Charsets.UTF_8);
+    assertStringHash(0xfc5ba834, "毎月１日,毎週月曜日", Charsets.UTF_8);
+    assertStringHash(0x8a5c3699, "surrogate pair: \uD83D\uDCB0", Charsets.UTF_8);
+
+    assertStringHash(0, "", Charsets.UTF_16LE);
+    assertStringHash(0x288418e4, "k", Charsets.UTF_16LE);
+    assertStringHash(0x5a0cb7c3, "hell", Charsets.UTF_16LE);
+    assertStringHash(0xd7c31989, "hello", Charsets.UTF_16LE);
+    assertStringHash(0x73564d8c, "http://www.google.com/", Charsets.UTF_16LE);
+    assertStringHash(0xe07db09c, "The quick brown fox jumps over the lazy dog", Charsets.UTF_16LE);
+    assertStringHash(0xfefa3e76, "ABCDefGHI\u0799", Charsets.UTF_16LE);
+    assertStringHash(0x6a7be132, "毎月１日,毎週月曜日", Charsets.UTF_16LE);
+    assertStringHash(0x5a2d41c7, "surrogate pair: \uD83D\uDCB0", Charsets.UTF_16LE);
+  }
+
+  @SuppressWarnings("deprecation")
+  private void assertStringHash(int expected, String string, Charset charset) {
+    if (allBmp(string)) {
+      assertHash(expected, murmur3_32().hashString(string, charset));
+    }
+    assertHash(expected, murmur3_32_fixed().hashString(string, charset));
+    assertHash(expected, murmur3_32().newHasher().putString(string, charset).hash());
+    assertHash(expected, murmur3_32_fixed().newHasher().putString(string, charset).hash());
+    assertHash(expected, murmur3_32().hashBytes(string.getBytes(charset)));
+    assertHash(expected, murmur3_32_fixed().hashBytes(string.getBytes(charset)));
+    assertHash(expected, murmur3_32().newHasher().putBytes(string.getBytes(charset)).hash());
+    assertHash(expected, murmur3_32_fixed().newHasher().putBytes(string.getBytes(charset)).hash());
+  }
+
+  private boolean allBmp(String string) {
+    // Ordinarily we'd use something like i += Character.charCount(string.codePointAt(i)) here. But
+    // we can get away with i++ because the whole point of this method is to return false if we find
+    // a code point that doesn't fit in a char.
+    for (int i = 0; i < string.length(); i++) {
+      if (string.codePointAt(i) > 0xffff) {
+        return false;
+      }
+    }
+    return true;
   }
 
   @SuppressWarnings("deprecation")
@@ -71,7 +110,7 @@ public void testSimpleStringUtf8() {
   }
 
   @SuppressWarnings("deprecation")
-  public void testStringInputsUtf8() {
+  public void testEncodedStringInputs() {
     Random rng = new Random(0);
     for (int z = 0; z < 100; z++) {
       String str;
@@ -88,9 +127,16 @@ public void testStringInputsUtf8() {
         builder.appendCodePoint(codePoints[i]);
       }
       str = builder.toString();
+      HashCode hashUtf8 = murmur3_32().hashBytes(str.getBytes(Charsets.UTF_8));
+      assertEquals(
+          hashUtf8, murmur3_32().newHasher().putBytes(str.getBytes(Charsets.UTF_8)).hash());
+      assertEquals(hashUtf8, murmur3_32().hashString(str, Charsets.UTF_8));
+      assertEquals(hashUtf8, murmur3_32().newHasher().putString(str, Charsets.UTF_8).hash());
+      HashCode hashUtf16 = murmur3_32().hashBytes(str.getBytes(Charsets.UTF_16));
       assertEquals(
-          murmur3_32().hashBytes(str.getBytes(Charsets.UTF_8)),
-          murmur3_32().hashString(str, Charsets.UTF_8));
+          hashUtf16, murmur3_32().newHasher().putBytes(str.getBytes(Charsets.UTF_16)).hash());
+      assertEquals(hashUtf16, murmur3_32().hashString(str, Charsets.UTF_16));
+      assertEquals(hashUtf16, murmur3_32().newHasher().putString(str, Charsets.UTF_16).hash());
     }
   }
 
@@ -138,8 +184,12 @@ public void testInvalidUnicodeHashString() {
     assertEquals(
         murmur3_32().hashBytes(str.getBytes(Charsets.UTF_8)),
         murmur3_32().hashString(str, Charsets.UTF_8));
+    assertEquals(
+        murmur3_32_fixed().hashBytes(str.getBytes(Charsets.UTF_8)),
+        murmur3_32().hashString(str, Charsets.UTF_8));
   }
 
+  @SuppressWarnings("deprecation")
   public void testInvalidUnicodeHasherPutString() {
     String str =
         new String(
@@ -147,5 +197,8 @@ public void testInvalidUnicodeHasherPutString() {
     assertEquals(
         murmur3_32().hashBytes(str.getBytes(Charsets.UTF_8)),
         murmur3_32().newHasher().putString(str, Charsets.UTF_8).hash());
+    assertEquals(
+        murmur3_32_fixed().hashBytes(str.getBytes(Charsets.UTF_8)),
+        murmur3_32_fixed().newHasher().putString(str, Charsets.UTF_8).hash());
   }
 }
diff --git a/android/guava-tests/test/com/google/common/io/BaseEncodingTest.java b/android/guava-tests/test/com/google/common/io/BaseEncodingTest.java
index 832fb0713fa9..c2fdf025731a 100644
--- a/android/guava-tests/test/com/google/common/io/BaseEncodingTest.java
+++ b/android/guava-tests/test/com/google/common/io/BaseEncodingTest.java
@@ -35,8 +35,8 @@
 import java.io.Reader;
 import java.io.StringReader;
 import java.io.StringWriter;
+import javax.annotation.CheckForNull;
 import junit.framework.TestCase;
-import org.checkerframework.checker.nullness.compatqual.NullableDecl;
 
 /**
  * Tests for {@code BaseEncoding}.
@@ -405,7 +405,7 @@ private static void assertFailsToDecode(BaseEncoding encoding, String cannotDeco
   }
 
   private static void assertFailsToDecode(
-      BaseEncoding encoding, String cannotDecode, @NullableDecl String expectedMessage) {
+      BaseEncoding encoding, String cannotDecode, @CheckForNull String expectedMessage) {
     // We use this somewhat weird pattern with an enum for each assertion we want to make as a way
     // of dealing with the fact that one of the assertions is @GwtIncompatible but we don't want to
     // have to have duplicate @GwtIncompatible test methods just to make that assertion.
@@ -419,7 +419,7 @@ enum AssertFailsToDecodeStrategy {
     DECODING_STREAM {
       @Override
       void assertFailsToDecode(
-          BaseEncoding encoding, String cannotDecode, @NullableDecl String expectedMessage) {
+          BaseEncoding encoding, String cannotDecode, @CheckForNull String expectedMessage) {
         // Regression test for case where DecodingException was swallowed by default implementation
         // of
         // InputStream.read(byte[], int, int)
@@ -440,14 +440,14 @@ void assertFailsToDecode(
     CAN_DECODE {
       @Override
       void assertFailsToDecode(
-          BaseEncoding encoding, String cannotDecode, @NullableDecl String expectedMessage) {
+          BaseEncoding encoding, String cannotDecode, @CheckForNull String expectedMessage) {
         assertFalse(encoding.canDecode(cannotDecode));
       }
     },
     DECODE {
       @Override
       void assertFailsToDecode(
-          BaseEncoding encoding, String cannotDecode, @NullableDecl String expectedMessage) {
+          BaseEncoding encoding, String cannotDecode, @CheckForNull String expectedMessage) {
         try {
           encoding.decode(cannotDecode);
           fail("Expected IllegalArgumentException");
@@ -461,7 +461,7 @@ void assertFailsToDecode(
     DECODE_CHECKED {
       @Override
       void assertFailsToDecode(
-          BaseEncoding encoding, String cannotDecode, @NullableDecl String expectedMessage) {
+          BaseEncoding encoding, String cannotDecode, @CheckForNull String expectedMessage) {
         try {
           encoding.decodeChecked(cannotDecode);
           fail("Expected DecodingException");
@@ -474,7 +474,7 @@ void assertFailsToDecode(
     };
 
     abstract void assertFailsToDecode(
-        BaseEncoding encoding, String cannotDecode, @NullableDecl String expectedMessage);
+        BaseEncoding encoding, String cannotDecode, @CheckForNull String expectedMessage);
   }
 
   @GwtIncompatible // Reader/Writer
diff --git a/android/guava-tests/test/com/google/common/io/ByteSourceTest.java b/android/guava-tests/test/com/google/common/io/ByteSourceTest.java
index f0ba829b22eb..3cf6cca44259 100644
--- a/android/guava-tests/test/com/google/common/io/ByteSourceTest.java
+++ b/android/guava-tests/test/com/google/common/io/ByteSourceTest.java
@@ -30,6 +30,7 @@
 import com.google.common.collect.ImmutableSet;
 import com.google.common.collect.Iterables;
 import com.google.common.hash.Hashing;
+import com.google.common.io.Closer.LoggingSuppressor;
 import com.google.common.primitives.UnsignedBytes;
 import com.google.common.testing.TestLogHandler;
 import java.io.ByteArrayOutputStream;
@@ -395,7 +396,7 @@ public void testConcat_infiniteIterable() throws IOException {
       ImmutableSet.of(BROKEN_CLOSE_SINK, BROKEN_OPEN_SINK, BROKEN_WRITE_SINK);
 
   public void testCopyExceptions() {
-    if (!Closer.SuppressingSuppressor.isAvailable()) {
+    if (Closer.create().suppressor instanceof LoggingSuppressor) {
       // test that exceptions are logged
 
       TestLogHandler logHandler = new TestLogHandler();
diff --git a/android/guava-tests/test/com/google/common/io/ByteSourceTester.java b/android/guava-tests/test/com/google/common/io/ByteSourceTester.java
index 490f1e6c5df7..75854125606a 100644
--- a/android/guava-tests/test/com/google/common/io/ByteSourceTester.java
+++ b/android/guava-tests/test/com/google/common/io/ByteSourceTester.java
@@ -38,7 +38,7 @@
 /**
  * A generator of {@code TestSuite} instances for testing {@code ByteSource} implementations.
  * Generates tests of a all methods on a {@code ByteSource} given various inputs the source is
- * expected to contain as well as as sub-suites for testing the {@code CharSource} view and {@code
+ * expected to contain as well as sub-suites for testing the {@code CharSource} view and {@code
  * slice()} views in the same way.
  *
  * @author Colin Decker
diff --git a/android/guava-tests/test/com/google/common/io/ByteStreamsTest.java b/android/guava-tests/test/com/google/common/io/ByteStreamsTest.java
index 3ae2c2559827..dddae1ffc21a 100644
--- a/android/guava-tests/test/com/google/common/io/ByteStreamsTest.java
+++ b/android/guava-tests/test/com/google/common/io/ByteStreamsTest.java
@@ -562,12 +562,49 @@ public void testNullOutputStream() throws Exception {
     // write to the output stream
     nos.write('n');
     String test = "Test string for NullOutputStream";
-    nos.write(test.getBytes());
-    nos.write(test.getBytes(), 2, 10);
+    byte[] bytes = test.getBytes(Charsets.US_ASCII);
+    nos.write(bytes);
+    nos.write(bytes, 2, 10);
+    nos.write(bytes, bytes.length - 5, 5);
     // nothing really to assert?
     assertSame(ByteStreams.nullOutputStream(), ByteStreams.nullOutputStream());
   }
 
+  public void testNullOutputStream_exceptions() throws Exception {
+    OutputStream nos = ByteStreams.nullOutputStream();
+    try {
+      nos.write(null);
+      fail();
+    } catch (NullPointerException expected) {
+    }
+    try {
+      nos.write(null, 0, 1);
+      fail();
+    } catch (NullPointerException expected) {
+    }
+    byte[] tenBytes = new byte[10];
+    try {
+      nos.write(tenBytes, -1, 1);
+      fail("Expected exception from negative offset");
+    } catch (IndexOutOfBoundsException expected) {
+    }
+    try {
+      nos.write(tenBytes, 1, -1);
+      fail("Expected exception from negative length");
+    } catch (IndexOutOfBoundsException expected) {
+    }
+    try {
+      nos.write(tenBytes, 9, 2);
+      fail("Expected exception from offset+length > array size");
+    } catch (IndexOutOfBoundsException expected) {
+    }
+    try {
+      nos.write(tenBytes, 9, 100);
+      fail("Expected exception from offset+length > array size");
+    } catch (IndexOutOfBoundsException expected) {
+    }
+  }
+
   public void testLimit() throws Exception {
     byte[] big = newPreFilledByteArray(5);
     InputStream bin = new ByteArrayInputStream(big);
diff --git a/android/guava-tests/test/com/google/common/io/CharSequenceReaderTest.java b/android/guava-tests/test/com/google/common/io/CharSequenceReaderTest.java
index 12bc17e588e3..dbe94fcf71fa 100644
--- a/android/guava-tests/test/com/google/common/io/CharSequenceReaderTest.java
+++ b/android/guava-tests/test/com/google/common/io/CharSequenceReaderTest.java
@@ -211,7 +211,7 @@ private static void assertReadsCorrectly(CharSequence charSequence) throws IOExc
     reader = new CharSequenceReader(charSequence);
     CharBuffer buf2 = CharBuffer.allocate(expected.length());
     assertEquals(expected.length() == 0 ? -1 : expected.length(), reader.read(buf2));
-    buf2.flip();
+    Java8Compatibility.flip(buf2);
     assertEquals(expected, buf2.toString());
     assertFullyRead(reader);
 
@@ -220,9 +220,9 @@ private static void assertReadsCorrectly(CharSequence charSequence) throws IOExc
     buf2 = CharBuffer.allocate(5);
     builder = new StringBuilder();
     while (reader.read(buf2) != -1) {
-      buf2.flip();
+      Java8Compatibility.flip(buf2);
       builder.append(buf2);
-      buf2.clear();
+      Java8Compatibility.clear(buf2);
     }
     assertEquals(expected, builder.toString());
     assertFullyRead(reader);
diff --git a/android/guava-tests/test/com/google/common/io/CharSourceTest.java b/android/guava-tests/test/com/google/common/io/CharSourceTest.java
index a1034904dd7c..6cc210b56c4e 100644
--- a/android/guava-tests/test/com/google/common/io/CharSourceTest.java
+++ b/android/guava-tests/test/com/google/common/io/CharSourceTest.java
@@ -25,6 +25,7 @@
 import com.google.common.collect.ImmutableSet;
 import com.google.common.collect.Iterables;
 import com.google.common.collect.Lists;
+import com.google.common.io.Closer.LoggingSuppressor;
 import com.google.common.testing.TestLogHandler;
 import java.io.BufferedReader;
 import java.io.IOException;
@@ -258,7 +259,7 @@ public void testConcat_infiniteIterable() throws IOException {
       ImmutableSet.of(BROKEN_CLOSE_SINK, BROKEN_OPEN_SINK, BROKEN_WRITE_SINK);
 
   public void testCopyExceptions() {
-    if (!Closer.SuppressingSuppressor.isAvailable()) {
+    if (Closer.create().suppressor instanceof LoggingSuppressor) {
       // test that exceptions are logged
 
       TestLogHandler logHandler = new TestLogHandler();
diff --git a/android/guava-tests/test/com/google/common/io/CloserTest.java b/android/guava-tests/test/com/google/common/io/CloserTest.java
index b97a3057698a..38ff700c8c14 100644
--- a/android/guava-tests/test/com/google/common/io/CloserTest.java
+++ b/android/guava-tests/test/com/google/common/io/CloserTest.java
@@ -24,14 +24,15 @@
 import com.google.common.collect.ImmutableList;
 import com.google.common.collect.ImmutableSet;
 import com.google.common.collect.Lists;
+import com.google.common.io.Closer.LoggingSuppressor;
 import com.google.common.testing.TestLogHandler;
 import java.io.Closeable;
 import java.io.IOException;
 import java.lang.reflect.Method;
 import java.util.List;
 import java.util.logging.LogRecord;
+import javax.annotation.CheckForNull;
 import junit.framework.TestCase;
-import org.checkerframework.checker.nullness.compatqual.NullableDecl;
 
 /**
  * Tests for {@link Closer}.
@@ -311,13 +312,12 @@ record = logHandler.getStoredLogRecords().get(1);
   }
 
   public static void testSuppressingSuppressorIfPossible() throws IOException {
+    Closer closer = Closer.create();
     // can't test the JDK7 suppressor when not running on JDK7
-    if (!Closer.SuppressingSuppressor.isAvailable()) {
+    if (closer.suppressor instanceof LoggingSuppressor) {
       return;
     }
 
-    Closer closer = new Closer(new Closer.SuppressingSuppressor());
-
     IOException thrownException = new IOException();
     IOException c1Exception = new IOException();
     RuntimeException c2Exception = new RuntimeException();
@@ -435,7 +435,7 @@ static TestCloseable throwsOnCreate() throws IOException {
       throw new IOException();
     }
 
-    private TestCloseable(@NullableDecl Throwable throwOnClose) {
+    private TestCloseable(@CheckForNull Throwable throwOnClose) {
       this.throwOnClose = throwOnClose;
     }
 
diff --git a/android/guava-tests/test/com/google/common/io/LittleEndianDataInputStreamTest.java b/android/guava-tests/test/com/google/common/io/LittleEndianDataInputStreamTest.java
index f8e40df25a98..160df410bed6 100644
--- a/android/guava-tests/test/com/google/common/io/LittleEndianDataInputStreamTest.java
+++ b/android/guava-tests/test/com/google/common/io/LittleEndianDataInputStreamTest.java
@@ -92,6 +92,7 @@ public void testReadUnsignedShort_eof() throws IOException {
     }
   }
 
+  @SuppressWarnings("DoNotCall")
   public void testReadLine() throws IOException {
     DataInput in = new LittleEndianDataInputStream(new ByteArrayInputStream(data));
     try {
diff --git a/android/guava-tests/test/com/google/common/io/PatternFilenameFilterTest.java b/android/guava-tests/test/com/google/common/io/PatternFilenameFilterTest.java
index 77ace52f2506..94ab1f01683a 100644
--- a/android/guava-tests/test/com/google/common/io/PatternFilenameFilterTest.java
+++ b/android/guava-tests/test/com/google/common/io/PatternFilenameFilterTest.java
@@ -16,6 +16,8 @@
 
 package com.google.common.io;
 
+import com.google.common.testing.NullPointerTester;
+import com.google.common.testing.NullPointerTester.Visibility;
 import java.io.File;
 import java.io.FilenameFilter;
 import java.util.regex.PatternSyntaxException;
@@ -46,4 +48,15 @@ public void testAccept() {
     // Show that dir is ignored
     assertTrue(filter.accept(null, "a"));
   }
+
+  public void testNulls() throws Exception {
+    NullPointerTester tester = new NullPointerTester();
+
+    tester.testConstructors(PatternFilenameFilter.class, Visibility.PACKAGE);
+    tester.testStaticMethods(PatternFilenameFilter.class, Visibility.PACKAGE); // currently none
+
+    // The reason that we skip this method is discussed in a comment on the method.
+    tester.ignore(PatternFilenameFilter.class.getMethod("accept", File.class, String.class));
+    tester.testInstanceMethods(new PatternFilenameFilter(".*"), Visibility.PACKAGE);
+  }
 }
diff --git a/android/guava-tests/test/com/google/common/io/SourceSinkFactories.java b/android/guava-tests/test/com/google/common/io/SourceSinkFactories.java
index 8bfa6e1ba12a..e70370e1d69b 100644
--- a/android/guava-tests/test/com/google/common/io/SourceSinkFactories.java
+++ b/android/guava-tests/test/com/google/common/io/SourceSinkFactories.java
@@ -37,7 +37,7 @@
 import java.nio.CharBuffer;
 import java.util.Arrays;
 import java.util.logging.Logger;
-import org.checkerframework.checker.nullness.compatqual.NullableDecl;
+import javax.annotation.CheckForNull;
 
 /**
  * {@link SourceSinkFactory} implementations.
@@ -305,7 +305,7 @@ private static class FileByteSinkFactory extends FileFactory implements ByteSink
 
     private final byte[] initialBytes;
 
-    private FileByteSinkFactory(@NullableDecl byte[] initialBytes) {
+    private FileByteSinkFactory(@CheckForNull byte[] initialBytes) {
       this.initialBytes = initialBytes;
     }
 
@@ -375,7 +375,7 @@ private static class FileCharSinkFactory extends FileFactory implements CharSink
 
     private final String initialString;
 
-    private FileCharSinkFactory(@NullableDecl String initialString) {
+    private FileCharSinkFactory(@CheckForNull String initialString) {
       this.initialString = initialString;
     }
 
@@ -407,9 +407,9 @@ public String getSinkContents() throws IOException {
       StringBuilder builder = new StringBuilder();
       CharBuffer buffer = CharBuffer.allocate(100);
       while (reader.read(buffer) != -1) {
-        buffer.flip();
+        Java8Compatibility.flip(buffer);
         builder.append(buffer);
-        buffer.clear();
+        Java8Compatibility.clear(buffer);
       }
       return builder.toString();
     }
diff --git a/android/guava-tests/test/com/google/common/io/SourceSinkTester.java b/android/guava-tests/test/com/google/common/io/SourceSinkTester.java
index 9b07355a6939..55a302f850c5 100644
--- a/android/guava-tests/test/com/google/common/io/SourceSinkTester.java
+++ b/android/guava-tests/test/com/google/common/io/SourceSinkTester.java
@@ -69,7 +69,7 @@ public class SourceSinkTester<S, T, F extends SourceSinkFactory<S, T>> extends T
           .put("\\n at EOF", "hello\nworld\n")
           .put("\\r at EOF", "hello\nworld\r")
           .put("lorem ipsum", LOREM_IPSUM)
-          .build();
+          .buildOrThrow();
 
   protected final F factory;
   protected final T data;
diff --git a/android/guava-tests/test/com/google/common/math/IntMathTest.java b/android/guava-tests/test/com/google/common/math/IntMathTest.java
index 12b23e214728..4db13adbddd5 100644
--- a/android/guava-tests/test/com/google/common/math/IntMathTest.java
+++ b/android/guava-tests/test/com/google/common/math/IntMathTest.java
@@ -137,10 +137,11 @@ public void testMaxLog10ForLeadingZeros() {
   @GwtIncompatible // BigIntegerMath // TODO(cpovirk): GWT-enable BigIntegerMath
   public void testConstantsHalfPowersOf10() {
     for (int i = 0; i < IntMath.halfPowersOf10.length; i++) {
-      assert IntMath.halfPowersOf10[i]
-          == Math.min(
+      assertEquals(
+          IntMath.halfPowersOf10[i],
+          Math.min(
               Integer.MAX_VALUE,
-              BigIntegerMath.sqrt(BigInteger.TEN.pow(2 * i + 1), FLOOR).longValue());
+              BigIntegerMath.sqrt(BigInteger.TEN.pow(2 * i + 1), FLOOR).longValue()));
     }
   }
 
diff --git a/android/guava-tests/test/com/google/common/math/MathPreconditionsTest.java b/android/guava-tests/test/com/google/common/math/MathPreconditionsTest.java
index 69719e013572..5dbe017c142d 100644
--- a/android/guava-tests/test/com/google/common/math/MathPreconditionsTest.java
+++ b/android/guava-tests/test/com/google/common/math/MathPreconditionsTest.java
@@ -289,4 +289,15 @@ public void testCheckNoOverflow_failure() {
       assertThat(expected).hasMessageThat().contains("testCheckNoOverflow_failure(0, 0)");
     }
   }
+
+  public void testNulls() {
+    /*
+     * Don't bother testing. All non-primitive parameters are used only to construct error messages.
+     * We never want to pass null for them, so we haven't annotated them to say that null is
+     * allowed. But at the same time, it seems wasteful to bother inserting the checkNotNull calls
+     * that NullPointerTester wants.
+     *
+     * (This empty method disables the automatic null testing provided by PackageSanityTests.)
+     */
+  }
 }
diff --git a/android/guava-tests/test/com/google/common/math/QuantilesAlgorithm.java b/android/guava-tests/test/com/google/common/math/QuantilesAlgorithm.java
index 54d310f0d2d6..ddb2064e20b6 100644
--- a/android/guava-tests/test/com/google/common/math/QuantilesAlgorithm.java
+++ b/android/guava-tests/test/com/google/common/math/QuantilesAlgorithm.java
@@ -53,7 +53,7 @@ Map<Integer, Double> multipleQuantiles(
       for (int index : indexes) {
         builder.put(index, singleQuantileFromSorted(index, scale, dataset));
       }
-      return builder.build();
+      return builder.buildOrThrow();
     }
 
     private double singleQuantileFromSorted(int index, int scale, double[] dataset) {
@@ -97,7 +97,7 @@ Map<Integer, Double> multipleQuantiles(
       for (int index : indexes) {
         builder.put(index, singleQuantile(index, scale, dataset));
       }
-      return builder.build();
+      return builder.buildOrThrow();
     }
   },
 
diff --git a/android/guava-tests/test/com/google/common/math/QuantilesTest.java b/android/guava-tests/test/com/google/common/math/QuantilesTest.java
index 5ac5f6e303e6..77c70207cdf9 100644
--- a/android/guava-tests/test/com/google/common/math/QuantilesTest.java
+++ b/android/guava-tests/test/com/google/common/math/QuantilesTest.java
@@ -41,8 +41,8 @@
 import java.util.Collections;
 import java.util.List;
 import java.util.Random;
+import javax.annotation.CheckForNull;
 import junit.framework.TestCase;
-import org.checkerframework.checker.nullness.compatqual.NullableDecl;
 
 /**
  * Tests for {@link Quantiles}.
@@ -92,7 +92,7 @@ public class QuantilesTest extends TestCase {
       Correspondence.from(
           new BinaryPredicate<Double, Double>() {
             @Override
-            public boolean apply(@NullableDecl Double actual, @NullableDecl Double expected) {
+            public boolean apply(@CheckForNull Double actual, @CheckForNull Double expected) {
               // Test for equality to allow non-finite values to match; otherwise, use the finite
               // test.
               return actual.equals(expected)
@@ -557,7 +557,7 @@ public void testPercentiles_indexes_varargsPairs_compute_doubleCollection() {
         }
         assertThat(percentiles().indexes(index1, index2).compute(PSEUDORANDOM_DATASET))
             .comparingValuesUsing(QUANTILE_CORRESPONDENCE)
-            .containsExactlyEntriesIn(expectedBuilder.build());
+            .containsExactlyEntriesIn(expectedBuilder.buildOrThrow());
       }
     }
   }
@@ -573,7 +573,7 @@ public void testPercentiles_indexes_varargsAll_compute_doubleCollection() {
     Collections.shuffle(indexes, random);
     assertThat(percentiles().indexes(Ints.toArray(indexes)).compute(PSEUDORANDOM_DATASET))
         .comparingValuesUsing(QUANTILE_CORRESPONDENCE)
-        .containsExactlyEntriesIn(expectedBuilder.build());
+        .containsExactlyEntriesIn(expectedBuilder.buildOrThrow());
   }
 
   @AndroidIncompatible // slow
@@ -589,7 +589,7 @@ public void testPercentiles_indexes_varargsAll_computeInPlace() {
     Collections.shuffle(indexes, random);
     assertThat(percentiles().indexes(Ints.toArray(indexes)).computeInPlace(dataset))
         .comparingValuesUsing(QUANTILE_CORRESPONDENCE)
-        .containsExactlyEntriesIn(expectedBuilder.build());
+        .containsExactlyEntriesIn(expectedBuilder.buildOrThrow());
     assertThat(dataset).usingExactEquality().containsExactlyElementsIn(PSEUDORANDOM_DATASET);
   }
 
diff --git a/android/guava-tests/test/com/google/common/net/HostAndPortTest.java b/android/guava-tests/test/com/google/common/net/HostAndPortTest.java
index 5e7eb2f73d71..65e80962bafa 100644
--- a/android/guava-tests/test/com/google/common/net/HostAndPortTest.java
+++ b/android/guava-tests/test/com/google/common/net/HostAndPortTest.java
@@ -59,6 +59,13 @@ public void testFromStringUnusedDefaultPort() {
     checkFromStringCase("[2001::2]:85", 77, "2001::2", 85, true);
   }
 
+  public void testFromStringNonAsciiDigits() {
+    // Same as testFromStringUnusedDefaultPort but with Gujarati digits for port numbers.
+    checkFromStringCase("gmail.com:૮1", 77, null, -1, false);
+    checkFromStringCase("192.0.2.2:૮૩", 77, null, -1, false);
+    checkFromStringCase("[2001::2]:૮૫", 77, null, -1, false);
+  }
+
   public void testFromStringBadPort() {
     // Out-of-range ports.
     checkFromStringCase("google.com:65536", 1, null, 99, false);
diff --git a/android/guava-tests/test/com/google/common/net/HostSpecifierTest.java b/android/guava-tests/test/com/google/common/net/HostSpecifierTest.java
index fadeff7aadf4..8112879a86d9 100644
--- a/android/guava-tests/test/com/google/common/net/HostSpecifierTest.java
+++ b/android/guava-tests/test/com/google/common/net/HostSpecifierTest.java
@@ -92,8 +92,9 @@ public void testNulls() {
   }
 
   private void assertGood(String spec) throws ParseException {
-    HostSpecifier.fromValid(spec); // Throws exception if not working correctly
-    HostSpecifier.from(spec);
+    // Throws exception if not working correctly
+    HostSpecifier unused = HostSpecifier.fromValid(spec);
+    unused = HostSpecifier.from(spec);
     assertTrue(HostSpecifier.isValid(spec));
   }
 
diff --git a/android/guava-tests/test/com/google/common/net/HttpHeadersTest.java b/android/guava-tests/test/com/google/common/net/HttpHeadersTest.java
index 9927e6b94e00..5361b3fcea61 100644
--- a/android/guava-tests/test/com/google/common/net/HttpHeadersTest.java
+++ b/android/guava-tests/test/com/google/common/net/HttpHeadersTest.java
@@ -50,8 +50,8 @@ public void testConstantNameMatchesString() throws Exception {
             .build();
     ImmutableSet<String> uppercaseAcronyms =
         ImmutableSet.of(
-            "CH", "ID", "DNT", "DNS", "HTTP2", "IP", "MD5", "P3P", "TE", "UA", "UID", "URL", "WWW",
-            "XSS");
+            "CH", "ID", "DNT", "DNS", "ECT", "HTTP2", "IP", "MD5", "P3P", "RTT", "TE", "UA", "UID",
+            "URL", "WWW", "XSS");
     assertConstantNameMatchesString(HttpHeaders.class, specialCases, uppercaseAcronyms);
   }
 
diff --git a/android/guava-tests/test/com/google/common/net/InetAddressesTest.java b/android/guava-tests/test/com/google/common/net/InetAddressesTest.java
index ed3aa272d3a6..be77e7b17f08 100644
--- a/android/guava-tests/test/com/google/common/net/InetAddressesTest.java
+++ b/android/guava-tests/test/com/google/common/net/InetAddressesTest.java
@@ -135,6 +135,20 @@ public void testForStringIPv4Input() throws UnknownHostException {
     assertTrue(InetAddresses.isInetAddress(ipStr));
   }
 
+  public void testForStringIPv4NonAsciiInput() throws UnknownHostException {
+    String ipStr = "૧૯૨.૧૬૮.૦.૧"; // 192.168.0.1 in Gujarati digits
+    // Shouldn't hit DNS, because it's an IP string literal.
+    InetAddress ipv4Addr;
+    try {
+      ipv4Addr = InetAddress.getByName(ipStr);
+    } catch (UnknownHostException e) {
+      // OK: this is probably Android, which is stricter.
+      return;
+    }
+    assertEquals(ipv4Addr, InetAddresses.forString(ipStr));
+    assertTrue(InetAddresses.isInetAddress(ipStr));
+  }
+
   public void testForStringIPv6Input() throws UnknownHostException {
     String ipStr = "3ffe::1";
     // Shouldn't hit DNS, because it's an IP string literal.
@@ -143,6 +157,20 @@ public void testForStringIPv6Input() throws UnknownHostException {
     assertTrue(InetAddresses.isInetAddress(ipStr));
   }
 
+  public void testForStringIPv6NonAsciiInput() throws UnknownHostException {
+    String ipStr = "૩ffe::૧"; // 3ffe::1 with Gujarati digits for 3 and 1
+    // Shouldn't hit DNS, because it's an IP string literal.
+    InetAddress ipv6Addr;
+    try {
+      ipv6Addr = InetAddress.getByName(ipStr);
+    } catch (UnknownHostException e) {
+      // OK: this is probably Android, which is stricter.
+      return;
+    }
+    assertEquals(ipv6Addr, InetAddresses.forString(ipStr));
+    assertTrue(InetAddresses.isInetAddress(ipStr));
+  }
+
   public void testForStringIPv6EightColons() throws UnknownHostException {
     ImmutableSet<String> eightColons =
         ImmutableSet.of("::7:6:5:4:3:2:1", "::7:6:5:4:3:2:0", "7:6:5:4:3:2:1::", "0:6:5:4:3:2:1::");
diff --git a/android/guava-tests/test/com/google/common/net/InternetDomainNameTest.java b/android/guava-tests/test/com/google/common/net/InternetDomainNameTest.java
index 7113fb45741a..c440ee53f509 100644
--- a/android/guava-tests/test/com/google/common/net/InternetDomainNameTest.java
+++ b/android/guava-tests/test/com/google/common/net/InternetDomainNameTest.java
@@ -232,7 +232,7 @@ public final class InternetDomainNameTest extends TestCase {
 
   public void testValid() {
     for (String name : VALID_NAME) {
-      InternetDomainName.from(name);
+      InternetDomainName unused = InternetDomainName.from(name);
     }
   }
 
@@ -392,7 +392,7 @@ public void testParentChild() {
     // These would throw an exception if leniency were not preserved during parent() and child()
     // calls.
     InternetDomainName child = parent.child(LOTS_OF_DELTAS);
-    child.child(LOTS_OF_DELTAS);
+    InternetDomainName unused = child.child(LOTS_OF_DELTAS);
   }
 
   public void testValidTopPrivateDomain() {
diff --git a/android/guava-tests/test/com/google/common/net/MediaTypeTest.java b/android/guava-tests/test/com/google/common/net/MediaTypeTest.java
index cec3cdd28cce..574db68e80b3 100644
--- a/android/guava-tests/test/com/google/common/net/MediaTypeTest.java
+++ b/android/guava-tests/test/com/google/common/net/MediaTypeTest.java
@@ -46,7 +46,6 @@
 import com.google.common.testing.NullPointerTester;
 import java.lang.reflect.Field;
 import java.nio.charset.Charset;
-import java.nio.charset.IllegalCharsetNameException;
 import java.nio.charset.UnsupportedCharsetException;
 import java.util.Arrays;
 import junit.framework.TestCase;
@@ -537,7 +536,7 @@ public void testGetCharset_illegalCharset() {
     try {
       mediaType.charset();
       fail();
-    } catch (IllegalCharsetNameException expected) {
+    } catch (IllegalArgumentException expected) {
     }
   }
 
diff --git a/android/guava-tests/test/com/google/common/net/PercentEscaperTest.java b/android/guava-tests/test/com/google/common/net/PercentEscaperTest.java
index 8443680e7f11..e600e4c7c1af 100644
--- a/android/guava-tests/test/com/google/common/net/PercentEscaperTest.java
+++ b/android/guava-tests/test/com/google/common/net/PercentEscaperTest.java
@@ -120,16 +120,11 @@ public void testBadArguments_badchars() {
     }
   }
 
-  /**
-   * Tests that if space is a safe character you cannot also specify 'plusForSpace' (throws {@link
-   * IllegalArgumentException}).
-   */
   public void testBadArguments_plusforspace() {
-    try {
-      new PercentEscaper(" ", false);
-    } catch (IllegalArgumentException e) {
-      fail("Space can be a 'safe' character if plusForSpace is false");
-    }
+    // space can be a safe char if plusForSpace is false
+    PercentEscaper unused = new PercentEscaper(" ", false);
+
+    // space cannot be a safe char is plusForSpace is true
     String msg = "plusForSpace cannot be specified when space is a 'safe' character";
     try {
       new PercentEscaper(" ", true);
diff --git a/android/guava-tests/test/com/google/common/primitives/BooleansTest.java b/android/guava-tests/test/com/google/common/primitives/BooleansTest.java
index 560c33700382..43ec04c4a4a4 100644
--- a/android/guava-tests/test/com/google/common/primitives/BooleansTest.java
+++ b/android/guava-tests/test/com/google/common/primitives/BooleansTest.java
@@ -299,7 +299,8 @@ public void testAsListEquals() {
     assertEquals(1, Booleans.asList(ARRAY_FALSE_TRUE).lastIndexOf(true));
     List<Boolean> reference = Booleans.asList(ARRAY_FALSE);
     assertEquals(Booleans.asList(ARRAY_FALSE), reference);
-    assertEquals(reference, reference);
+    // Explicitly call `equals`; `assertEquals` might return fast
+    assertTrue(reference.equals(reference));
   }
 
   public void testAsListHashcode() {
diff --git a/android/guava-tests/test/com/google/common/primitives/UnsignedLongTest.java b/android/guava-tests/test/com/google/common/primitives/UnsignedLongTest.java
index dd2a8ab88bfc..cfa2862573aa 100644
--- a/android/guava-tests/test/com/google/common/primitives/UnsignedLongTest.java
+++ b/android/guava-tests/test/com/google/common/primitives/UnsignedLongTest.java
@@ -36,13 +36,23 @@ public class UnsignedLongTest extends TestCase {
   static {
     ImmutableSet.Builder<Long> testLongsBuilder = ImmutableSet.builder();
     ImmutableSet.Builder<BigInteger> testBigIntegersBuilder = ImmutableSet.builder();
+
+    // The values here look like 111...11101...010 in binary, where the initial 111...1110 takes
+    // up exactly as many bits as can be represented in the significand (24 for float, 53 for
+    // double). That final 0 should be rounded up to 1 because the remaining bits make that number
+    // slightly nearer.
+    long floatConversionTest = 0xfffffe8000000002L;
+    long doubleConversionTest = 0xfffffffffffff402L;
+
     for (long i = -3; i <= 3; i++) {
       testLongsBuilder
           .add(i)
           .add(Long.MAX_VALUE + i)
           .add(Long.MIN_VALUE + i)
           .add(Integer.MIN_VALUE + i)
-          .add(Integer.MAX_VALUE + i);
+          .add(Integer.MAX_VALUE + i)
+          .add(floatConversionTest + i)
+          .add(doubleConversionTest + i);
       BigInteger bigI = BigInteger.valueOf(i);
       testBigIntegersBuilder
           .add(bigI)
@@ -130,17 +140,26 @@ public void testToStringRadixQuick() {
     }
   }
 
+  @AndroidIncompatible // b/28251030, re-enable when the fix is everywhere we run this test
   public void testFloatValue() {
     for (long value : TEST_LONGS) {
       UnsignedLong unsignedValue = UnsignedLong.fromLongBits(value);
-      assertEquals(unsignedValue.bigIntegerValue().floatValue(), unsignedValue.floatValue());
+      assertEquals(
+          "Float value of " + unsignedValue,
+          unsignedValue.bigIntegerValue().floatValue(),
+          unsignedValue.floatValue(),
+          0.0f);
     }
   }
 
   public void testDoubleValue() {
     for (long value : TEST_LONGS) {
       UnsignedLong unsignedValue = UnsignedLong.fromLongBits(value);
-      assertEquals(unsignedValue.bigIntegerValue().doubleValue(), unsignedValue.doubleValue());
+      assertEquals(
+          "Double value of " + unsignedValue,
+          unsignedValue.bigIntegerValue().doubleValue(),
+          unsignedValue.doubleValue(),
+          0.0);
     }
   }
 
diff --git a/android/guava-tests/test/com/google/common/reflect/ElementTest.java b/android/guava-tests/test/com/google/common/reflect/ElementTest.java
deleted file mode 100644
index abe63ba56163..000000000000
--- a/android/guava-tests/test/com/google/common/reflect/ElementTest.java
+++ /dev/null
@@ -1,247 +0,0 @@
-/*
- * Copyright (C) 2012 The Guava Authors
- *
- * Licensed under the Apache License, Version 2.0 (the "License");
- * you may not use this file except in compliance with the License.
- * You may obtain a copy of the License at
- *
- * http://www.apache.org/licenses/LICENSE-2.0
- *
- * Unless required by applicable law or agreed to in writing, software
- * distributed under the License is distributed on an "AS IS" BASIS,
- * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
- * See the License for the specific language governing permissions and
- * limitations under the License.
- */
-
-package com.google.common.reflect;
-
-import com.google.common.testing.EqualsTester;
-import com.google.common.testing.NullPointerTester;
-import java.lang.annotation.Retention;
-import java.lang.annotation.RetentionPolicy;
-import java.lang.reflect.Constructor;
-import junit.framework.TestCase;
-
-/**
- * Unit tests of {@link Element}.
- *
- * @author Ben Yu
- */
-public class ElementTest extends TestCase {
-
-  public void testPrivateField() throws Exception {
-    Element element = A.field("privateField");
-    assertTrue(element.isPrivate());
-    assertFalse(element.isAbstract());
-    assertFalse(element.isPackagePrivate());
-    assertFalse(element.isProtected());
-    assertFalse(element.isPublic());
-    assertFalse(element.isFinal());
-    assertFalse(element.isStatic());
-    assertTrue(element.isAnnotationPresent(Tested.class));
-  }
-
-  public void testPackagePrivateField() throws Exception {
-    Element element = A.field("packagePrivateField");
-    assertFalse(element.isPrivate());
-    assertTrue(element.isPackagePrivate());
-    assertFalse(element.isProtected());
-    assertFalse(element.isPublic());
-    assertFalse(element.isFinal());
-    assertFalse(element.isStatic());
-    assertTrue(element.isAnnotationPresent(Tested.class));
-  }
-
-  public void testProtectedField() throws Exception {
-    Element element = A.field("protectedField");
-    assertFalse(element.isPrivate());
-    assertFalse(element.isPackagePrivate());
-    assertTrue(element.isProtected());
-    assertFalse(element.isPublic());
-    assertFalse(element.isFinal());
-    assertFalse(element.isStatic());
-    assertTrue(element.isAnnotationPresent(Tested.class));
-  }
-
-  public void testPublicField() throws Exception {
-    Element element = A.field("publicField");
-    assertFalse(element.isPrivate());
-    assertFalse(element.isPackagePrivate());
-    assertFalse(element.isProtected());
-    assertTrue(element.isPublic());
-    assertFalse(element.isFinal());
-    assertFalse(element.isStatic());
-    assertTrue(element.isAnnotationPresent(Tested.class));
-  }
-
-  public void testFinalField() throws Exception {
-    Element element = A.field("finalField");
-    assertTrue(element.isFinal());
-    assertFalse(element.isStatic());
-    assertTrue(element.isAnnotationPresent(Tested.class));
-  }
-
-  public void testStaticField() throws Exception {
-    Element element = A.field("staticField");
-    assertTrue(element.isStatic());
-    assertTrue(element.isAnnotationPresent(Tested.class));
-  }
-
-  public void testVolatileField() throws Exception {
-    Element element = A.field("volatileField");
-    assertTrue(element.isVolatile());
-  }
-
-  public void testTransientField() throws Exception {
-    Element element = A.field("transientField");
-    assertTrue(element.isTransient());
-  }
-
-  public void testConstructor() throws Exception {
-    Element element = A.constructor();
-    assertTrue(element.isPublic());
-    assertFalse(element.isPackagePrivate());
-    assertFalse(element.isAbstract());
-    assertFalse(element.isStatic());
-    assertTrue(element.isAnnotationPresent(Tested.class));
-  }
-
-  public void testAbstractMethod() throws Exception {
-    Element element = A.method("abstractMethod");
-    assertTrue(element.isPackagePrivate());
-    assertTrue(element.isAbstract());
-    assertFalse(element.isFinal());
-    assertTrue(element.isAnnotationPresent(Tested.class));
-  }
-
-  public void testOverridableMethod() throws Exception {
-    Element element = A.method("overridableMethod");
-    assertTrue(element.isPackagePrivate());
-    assertFalse(element.isAbstract());
-    assertFalse(element.isFinal());
-    assertTrue(element.isAnnotationPresent(Tested.class));
-  }
-
-  public void testPrivateMethod() throws Exception {
-    Element element = A.method("privateMethod");
-    assertFalse(element.isAbstract());
-    assertTrue(element.isPrivate());
-    assertFalse(element.isPackagePrivate());
-    assertFalse(element.isPublic());
-    assertFalse(element.isProtected());
-    assertTrue(element.isAnnotationPresent(Tested.class));
-  }
-
-  public void testProtectedMethod() throws Exception {
-    Element element = A.method("protectedMethod");
-    assertFalse(element.isAbstract());
-    assertFalse(element.isPrivate());
-    assertFalse(element.isPackagePrivate());
-    assertFalse(element.isFinal());
-    assertFalse(element.isPublic());
-    assertTrue(element.isProtected());
-    assertTrue(element.isAnnotationPresent(Tested.class));
-  }
-
-  public void testFinalMethod() throws Exception {
-    Element element = A.method("publicFinalMethod");
-    assertFalse(element.isAbstract());
-    assertFalse(element.isPrivate());
-    assertTrue(element.isFinal());
-    assertTrue(element.isPublic());
-    assertTrue(element.isAnnotationPresent(Tested.class));
-  }
-
-  public void testNativeMethod() throws Exception {
-    Element element = A.method("nativeMethod");
-    assertTrue(element.isNative());
-    assertTrue(element.isPackagePrivate());
-  }
-
-  public void testSynchronizedMethod() throws Exception {
-    Element element = A.method("synchronizedMethod");
-    assertTrue(element.isSynchronized());
-  }
-
-  public void testUnannotatedMethod() throws Exception {
-    Element element = A.method("notAnnotatedMethod");
-    assertFalse(element.isAnnotationPresent(Tested.class));
-  }
-
-  public void testEquals() throws Exception {
-    new EqualsTester()
-        .addEqualityGroup(A.field("privateField"), A.field("privateField"))
-        .addEqualityGroup(A.field("publicField"))
-        .addEqualityGroup(A.constructor(), A.constructor())
-        .addEqualityGroup(A.method("privateMethod"), A.method("privateMethod"))
-        .addEqualityGroup(A.method("publicFinalMethod"))
-        .testEquals();
-  }
-
-  public void testNulls() {
-    new NullPointerTester().testAllPublicStaticMethods(Element.class);
-  }
-
-  @Retention(RetentionPolicy.RUNTIME)
-  private @interface Tested {}
-
-  private abstract static class A {
-    @Tested private boolean privateField;
-    @Tested int packagePrivateField;
-    @Tested protected int protectedField;
-    @Tested public String publicField;
-    @Tested private static Iterable<String> staticField;
-    @Tested private final Object finalField;
-    private volatile char volatileField;
-    private transient long transientField;
-
-    @Tested
-    public A(Object finalField) {
-      this.finalField = finalField;
-    }
-
-    @Tested
-    abstract void abstractMethod();
-
-    @Tested
-    void overridableMethod() {}
-
-    @Tested
-    protected void protectedMethod() {}
-
-    @Tested
-    private void privateMethod() {}
-
-    @Tested
-    public final void publicFinalMethod() {}
-
-    void notAnnotatedMethod() {}
-
-    static Element field(String name) throws Exception {
-      Element element = new Element(A.class.getDeclaredField(name));
-      assertEquals(name, element.getName());
-      assertEquals(A.class, element.getDeclaringClass());
-      return element;
-    }
-
-    static Element constructor() throws Exception {
-      Constructor<?> constructor = A.class.getDeclaredConstructor(Object.class);
-      Element element = new Element(constructor);
-      assertEquals(constructor.getName(), element.getName());
-      assertEquals(A.class, element.getDeclaringClass());
-      return element;
-    }
-
-    static Element method(String name, Class<?>... parameterTypes) throws Exception {
-      Element element = new Element(A.class.getDeclaredMethod(name, parameterTypes));
-      assertEquals(name, element.getName());
-      assertEquals(A.class, element.getDeclaringClass());
-      return element;
-    }
-
-    native void nativeMethod();
-
-    synchronized void synchronizedMethod() {}
-  }
-}
diff --git a/android/guava-tests/test/com/google/common/reflect/InvokableTest.java b/android/guava-tests/test/com/google/common/reflect/InvokableTest.java
index 816aed3326ee..e545bdd1b903 100644
--- a/android/guava-tests/test/com/google/common/reflect/InvokableTest.java
+++ b/android/guava-tests/test/com/google/common/reflect/InvokableTest.java
@@ -19,18 +19,21 @@
 import static com.google.common.truth.Truth.assertThat;
 
 import com.google.common.collect.ImmutableList;
+import com.google.common.collect.ImmutableSet;
 import com.google.common.collect.Iterables;
 import com.google.common.testing.EqualsTester;
 import com.google.common.testing.NullPointerTester;
 import java.lang.annotation.Retention;
 import java.lang.annotation.RetentionPolicy;
+import java.lang.reflect.AccessibleObject;
 import java.lang.reflect.Constructor;
 import java.lang.reflect.Method;
+import java.lang.reflect.Modifier;
 import java.lang.reflect.ParameterizedType;
 import java.lang.reflect.TypeVariable;
 import java.util.Collections;
+import javax.annotation.CheckForNull;
 import junit.framework.TestCase;
-import org.checkerframework.checker.nullness.compatqual.NullableDecl;
 
 /**
  * Unit tests for {@link Invokable}.
@@ -39,6 +42,180 @@
  */
 @AndroidIncompatible // lots of failures, possibly some related to bad equals() implementations?
 public class InvokableTest extends TestCase {
+  // Historically Invokable inherited from java.lang.reflect.AccessibleObject. That's no longer the
+  // case, but we do check that its API still has the same public methods. We exclude some methods
+  // that were added in Java 9 and that people probably weren't calling via Invokable, namely
+  // `boolean canAccess(Object)`.
+  public void testApiCompatibleWithAccessibleObject() {
+    ImmutableSet<String> invokableMethods =
+        publicMethodSignatures(Invokable.class, ImmutableSet.<String>of());
+    ImmutableSet<String> accesibleObjectMethods =
+        publicMethodSignatures(AccessibleObject.class, ImmutableSet.of("canAccess"));
+    assertThat(invokableMethods).containsAtLeastElementsIn(accesibleObjectMethods);
+    Class<?> genericDeclaration;
+    try {
+      genericDeclaration = Class.forName("java.lang.reflect.GenericDeclaration");
+      ImmutableSet<String> genericDeclarationMethods =
+          publicMethodSignatures(genericDeclaration, ImmutableSet.<String>of());
+      assertThat(invokableMethods).containsAtLeastElementsIn(genericDeclarationMethods);
+    } catch (ClassNotFoundException e) {
+      // OK: we're on Java 7, which doesn't have this class
+    }
+  }
+
+  private static ImmutableSet<String> publicMethodSignatures(
+      Class<?> c, ImmutableSet<String> ignore) {
+    ImmutableSet.Builder<String> methods = ImmutableSet.builder();
+    for (Method method : c.getMethods()) {
+      if (Modifier.isStatic(method.getModifiers()) || ignore.contains(method.getName())) {
+        continue;
+      }
+      StringBuilder signature =
+          new StringBuilder()
+              .append(typeName(method.getReturnType()))
+              .append(" ")
+              .append(method.getName())
+              .append("(");
+      String sep = "";
+      for (Class<?> param : method.getParameterTypes()) {
+        signature.append(sep).append(typeName(param));
+        sep = ", ";
+      }
+      methods.add(signature.append(")").toString());
+    }
+    return methods.build();
+  }
+
+  private static String typeName(Class<?> type) {
+    return type.isArray() ? typeName(type.getComponentType()) + "[]" : type.getName();
+  }
+
+  public void testConstructor() throws Exception {
+    Invokable<A, A> invokable = A.constructor();
+    assertTrue(invokable.isPublic());
+    assertFalse(invokable.isPackagePrivate());
+    assertFalse(invokable.isAbstract());
+    assertFalse(invokable.isStatic());
+    assertTrue(invokable.isAnnotationPresent(Tested.class));
+  }
+
+  public void testAbstractMethod() throws Exception {
+    Invokable<?, Object> invokable = A.method("abstractMethod");
+    assertTrue(invokable.isPackagePrivate());
+    assertTrue(invokable.isAbstract());
+    assertFalse(invokable.isFinal());
+    assertTrue(invokable.isAnnotationPresent(Tested.class));
+  }
+
+  public void testOverridableMethod() throws Exception {
+    Invokable<?, Object> invokable = A.method("overridableMethod");
+    assertTrue(invokable.isPackagePrivate());
+    assertFalse(invokable.isAbstract());
+    assertFalse(invokable.isFinal());
+    assertTrue(invokable.isAnnotationPresent(Tested.class));
+  }
+
+  public void testPrivateMethod() throws Exception {
+    Invokable<?, Object> invokable = A.method("privateMethod");
+    assertFalse(invokable.isAbstract());
+    assertTrue(invokable.isPrivate());
+    assertFalse(invokable.isPackagePrivate());
+    assertFalse(invokable.isPublic());
+    assertFalse(invokable.isProtected());
+    assertTrue(invokable.isAnnotationPresent(Tested.class));
+  }
+
+  public void testProtectedMethod() throws Exception {
+    Invokable<?, Object> invokable = A.method("protectedMethod");
+    assertFalse(invokable.isAbstract());
+    assertFalse(invokable.isPrivate());
+    assertFalse(invokable.isPackagePrivate());
+    assertFalse(invokable.isFinal());
+    assertFalse(invokable.isPublic());
+    assertTrue(invokable.isProtected());
+    assertTrue(invokable.isAnnotationPresent(Tested.class));
+  }
+
+  public void testFinalMethod() throws Exception {
+    Invokable<?, Object> invokable = A.method("publicFinalMethod");
+    assertFalse(invokable.isAbstract());
+    assertFalse(invokable.isPrivate());
+    assertTrue(invokable.isFinal());
+    assertTrue(invokable.isPublic());
+    assertTrue(invokable.isAnnotationPresent(Tested.class));
+  }
+
+  public void testNativeMethod() throws Exception {
+    Invokable<?, Object> invokable = A.method("nativeMethod");
+    assertTrue(invokable.isNative());
+    assertTrue(invokable.isPackagePrivate());
+  }
+
+  public void testSynchronizedMethod() throws Exception {
+    Invokable<?, Object> invokable = A.method("synchronizedMethod");
+    assertTrue(invokable.isSynchronized());
+  }
+
+  public void testUnannotatedMethod() throws Exception {
+    Invokable<?, Object> invokable = A.method("notAnnotatedMethod");
+    assertFalse(invokable.isAnnotationPresent(Tested.class));
+  }
+
+  @Retention(RetentionPolicy.RUNTIME)
+  private @interface Tested {}
+
+  private abstract static class A {
+    @Tested private boolean privateField;
+    @Tested int packagePrivateField;
+    @Tested protected int protectedField;
+    @Tested public String publicField;
+    @Tested private static Iterable<String> staticField;
+    @Tested private final Object finalField;
+    private volatile char volatileField;
+    private transient long transientField;
+
+    @Tested
+    public A(Object finalField) {
+      this.finalField = finalField;
+    }
+
+    @Tested
+    abstract void abstractMethod();
+
+    @Tested
+    void overridableMethod() {}
+
+    @Tested
+    protected void protectedMethod() {}
+
+    @Tested
+    private void privateMethod() {}
+
+    @Tested
+    public final void publicFinalMethod() {}
+
+    void notAnnotatedMethod() {}
+
+    static Invokable<A, A> constructor() throws Exception {
+      Constructor<A> constructor = A.class.getDeclaredConstructor(Object.class);
+      Invokable<A, A> invokable = Invokable.from(constructor);
+      assertEquals(constructor.getName(), invokable.getName());
+      assertEquals(A.class, invokable.getDeclaringClass());
+      return invokable;
+    }
+
+    static Invokable<?, Object> method(String name, Class<?>... parameterTypes) throws Exception {
+      Invokable<?, Object> invokable =
+          Invokable.from(A.class.getDeclaredMethod(name, parameterTypes));
+      assertEquals(name, invokable.getName());
+      assertEquals(A.class, invokable.getDeclaringClass());
+      return invokable;
+    }
+
+    native void nativeMethod();
+
+    synchronized void synchronizedMethod() {}
+  }
 
   public void testConstructor_returnType() throws Exception {
     assertEquals(Prepender.class, Prepender.constructor().getReturnType().getType());
@@ -74,7 +251,7 @@ public void testConstructor_exceptionTypes() throws Exception {
   public void testConstructor_typeParameters() throws Exception {
     TypeVariable<?>[] variables = Prepender.constructor().getTypeParameters();
     assertThat(variables).hasLength(1);
-    assertEquals("A", variables[0].getName());
+    assertEquals("T", variables[0].getName());
   }
 
   public void testConstructor_parameters() throws Exception {
@@ -343,7 +520,7 @@ public void testInnerClassWithOneParameterConstructor() {
 
   private class InnerWithAnnotatedConstructorParameter {
     @SuppressWarnings("unused") // called by reflection
-    InnerWithAnnotatedConstructorParameter(@NullableDecl String s) {}
+    InnerWithAnnotatedConstructorParameter(@CheckForNull String s) {}
   }
 
   public void testInnerClassWithAnnotatedConstructorParameter() {
@@ -424,7 +601,7 @@ public void run() {
   }
 
   public void testAnonymousClassInConstructor() {
-    new AnonymousClassInConstructor();
+    AnonymousClassInConstructor unused = new AnonymousClassInConstructor();
   }
 
   private static class AnonymousClassInConstructor {
@@ -444,7 +621,7 @@ public void run() {
   }
 
   public void testLocalClassInInstanceInitializer() {
-    new LocalClassInInstanceInitializer();
+    LocalClassInInstanceInitializer unused = new LocalClassInInstanceInitializer();
   }
 
   private static class LocalClassInInstanceInitializer {
@@ -456,7 +633,7 @@ class Local {}
   }
 
   public void testLocalClassInStaticInitializer() {
-    new LocalClassInStaticInitializer();
+    LocalClassInStaticInitializer unused = new LocalClassInStaticInitializer();
   }
 
   private static class LocalClassInStaticInitializer {
@@ -468,7 +645,8 @@ class Local {}
   }
 
   public void testLocalClassWithSeeminglyHiddenThisInStaticInitializer_BUG() {
-    new LocalClassWithSeeminglyHiddenThisInStaticInitializer();
+    LocalClassWithSeeminglyHiddenThisInStaticInitializer unused =
+        new LocalClassWithSeeminglyHiddenThisInStaticInitializer();
   }
 
   /**
@@ -506,7 +684,7 @@ public LocalWithOneParameterConstructor(String x) {
   public void testLocalClassWithAnnotatedConstructorParameter() throws Exception {
     class LocalWithAnnotatedConstructorParameter {
       @SuppressWarnings("unused") // called by reflection
-      LocalWithAnnotatedConstructorParameter(@NullableDecl String s) {}
+      LocalWithAnnotatedConstructorParameter(@CheckForNull String s) {}
     }
     Constructor<?> constructor =
         LocalWithAnnotatedConstructorParameter.class.getDeclaredConstructors()[0];
@@ -530,6 +708,9 @@ class LocalWithGenericConstructorParameter {
 
   public void testEquals() throws Exception {
     new EqualsTester()
+        .addEqualityGroup(A.constructor(), A.constructor())
+        .addEqualityGroup(A.method("privateMethod"), A.method("privateMethod"))
+        .addEqualityGroup(A.method("publicFinalMethod"))
         .addEqualityGroup(Prepender.constructor(), Prepender.constructor())
         .addEqualityGroup(Prepender.constructor(String.class, int.class))
         .addEqualityGroup(Prepender.method("privateMethod"), Prepender.method("privateMethod"))
@@ -562,7 +743,7 @@ private static class Prepender {
     }
 
     // just for testing
-    private <A> Prepender() {
+    private <T> Prepender() {
       this(null, 0);
     }
 
diff --git a/android/guava-tests/test/com/google/common/reflect/TypeTokenTest.java b/android/guava-tests/test/com/google/common/reflect/TypeTokenTest.java
index 171ef49fdb80..79732090a132 100644
--- a/android/guava-tests/test/com/google/common/reflect/TypeTokenTest.java
+++ b/android/guava-tests/test/com/google/common/reflect/TypeTokenTest.java
@@ -402,7 +402,7 @@ public <T> void testGetGenericSuperclass_typeVariable_unbounded() {
     assertEquals(TypeToken.of(Object.class), new TypeToken<T[]>() {}.getGenericSuperclass());
   }
 
-  public <T extends ArrayList<String> & CharSequence>
+  public <T extends ArrayList<String> & Serializable>
       void testGetGenericSuperclass_typeVariable_boundIsClass() {
     assertEquals(
         new TypeToken<ArrayList<String>>() {},
@@ -410,7 +410,7 @@ void testGetGenericSuperclass_typeVariable_boundIsClass() {
     assertEquals(TypeToken.of(Object.class), new TypeToken<T[]>() {}.getGenericSuperclass());
   }
 
-  public <T extends Enum<T> & CharSequence>
+  public <T extends Enum<T> & Serializable>
       void testGetGenericSuperclass_typeVariable_boundIsFBoundedClass() {
     assertEquals(
         new TypeToken<Enum<T>>() {},
@@ -418,13 +418,13 @@ void testGetGenericSuperclass_typeVariable_boundIsFBoundedClass() {
     assertEquals(TypeToken.of(Object.class), new TypeToken<T[]>() {}.getGenericSuperclass());
   }
 
-  public <T extends List<String> & CharSequence>
+  public <T extends List<String> & Serializable>
       void testGetGenericSuperclass_typeVariable_boundIsInterface() {
     assertNull(TypeToken.of(new TypeCapture<T>() {}.capture()).getGenericSuperclass());
     assertEquals(TypeToken.of(Object.class), new TypeToken<T[]>() {}.getGenericSuperclass());
   }
 
-  public <T extends ArrayList<String> & CharSequence, T1 extends T>
+  public <T extends ArrayList<String> & Serializable, T1 extends T>
       void testGetGenericSuperclass_typeVariable_boundIsTypeVariableAndClass() {
     assertEquals(
         TypeToken.of(new TypeCapture<T>() {}.capture()),
@@ -432,7 +432,7 @@ void testGetGenericSuperclass_typeVariable_boundIsTypeVariableAndClass() {
     assertEquals(TypeToken.of(Object.class), new TypeToken<T[]>() {}.getGenericSuperclass());
   }
 
-  public <T extends List<String> & CharSequence, T1 extends T>
+  public <T extends List<String> & Serializable, T1 extends T>
       void testGetGenericSuperclass_typeVariable_boundIsTypeVariableAndInterface() {
     assertNull(TypeToken.of(new TypeCapture<T1>() {}.capture()).getGenericSuperclass());
     assertEquals(TypeToken.of(Object.class), new TypeToken<T1[]>() {}.getGenericSuperclass());
@@ -1101,7 +1101,7 @@ public void testGetSupertype_withoutTypeVariable() {
   }
 
   public void testGetSupertype_chained() {
-    @SuppressWarnings("unchecked") // StringListIterable extensd ListIterable<String>
+    @SuppressWarnings("unchecked") // StringListIterable extends ListIterable<String>
     TypeToken<ListIterable<String>> listIterableType =
         (TypeToken<ListIterable<String>>)
             TypeToken.of(StringListIterable.class).getSupertype(ListIterable.class);
@@ -1793,7 +1793,7 @@ private abstract static class RawTypeConsistencyTester<T extends Enum<T> & CharS
 
     abstract <T2 extends CharSequence & Iterable<T2>> void acceptT2(T2 t2);
 
-    static void verifyConsitentRawType() {
+    static void verifyConsistentRawType() {
       for (Method method : RawTypeConsistencyTester.class.getDeclaredMethods()) {
         assertEquals(
             method.getReturnType(), TypeToken.of(method.getGenericReturnType()).getRawType());
@@ -1807,7 +1807,7 @@ static void verifyConsitentRawType() {
   }
 
   public void testRawTypes() {
-    RawTypeConsistencyTester.verifyConsitentRawType();
+    RawTypeConsistencyTester.verifyConsistentRawType();
     assertEquals(Object.class, TypeToken.of(Types.subtypeOf(Object.class)).getRawType());
     assertEquals(
         CharSequence.class, TypeToken.of(Types.subtypeOf(CharSequence.class)).getRawType());
diff --git a/android/guava-tests/test/com/google/common/util/concurrent/AbstractAbstractFutureTest.java b/android/guava-tests/test/com/google/common/util/concurrent/AbstractAbstractFutureTest.java
index f49b96245db4..991cada29a11 100644
--- a/android/guava-tests/test/com/google/common/util/concurrent/AbstractAbstractFutureTest.java
+++ b/android/guava-tests/test/com/google/common/util/concurrent/AbstractAbstractFutureTest.java
@@ -359,7 +359,6 @@ public void testNegativeTimeout() throws Exception {
   }
 
   @GwtIncompatible // threads
-
   public void testOverflowTimeout() throws Exception {
     // First, sanity check that naive multiplication would really overflow to a negative number:
     long nanosPerSecond = NANOSECONDS.convert(1, SECONDS);
diff --git a/android/guava-tests/test/com/google/common/util/concurrent/ClosingFutureTest.java b/android/guava-tests/test/com/google/common/util/concurrent/AbstractClosingFutureTest.java
similarity index 91%
rename from android/guava-tests/test/com/google/common/util/concurrent/ClosingFutureTest.java
rename to android/guava-tests/test/com/google/common/util/concurrent/AbstractClosingFutureTest.java
index f5f12db824ca..8f0fde236602 100644
--- a/android/guava-tests/test/com/google/common/util/concurrent/ClosingFutureTest.java
+++ b/android/guava-tests/test/com/google/common/util/concurrent/AbstractClosingFutureTest.java
@@ -81,7 +81,7 @@
  * ClosingFuture#finishToValueAndCloser(ValueAndCloserConsumer, Executor)} paths to complete a
  * {@link ClosingFuture} pipeline.
  */
-public abstract class ClosingFutureTest extends TestCase {
+public abstract class AbstractClosingFutureTest extends TestCase {
   // TODO(dpb): Use Expect once that supports JUnit 3, or we can use JUnit 4.
   final List<AssertionError> failures = new ArrayList<>();
   final StandardSubjectBuilder expect =
@@ -1616,7 +1616,7 @@ public Closeable call(DeferredCloser closer) throws Exception {
 
   /**
    * Marks the given step final and waits for it to fail. Expects the failure exception to match
-   * {@link ClosingFutureTest#exception}.
+   * {@link AbstractClosingFutureTest#exception}.
    */
   abstract void assertFinallyFailsWithException(ClosingFuture<?> closingFuture);
 
@@ -1628,191 +1628,6 @@ void waitUntilClosed(ClosingFuture<?> closingFuture) {
     assertTrue(awaitUninterruptibly(closingFuture.whenClosedCountDown(), 1, SECONDS));
   }
 
-  /** Tests for {@link ClosingFuture} that exercise {@link ClosingFuture#finishToFuture()}. */
-
-  public static class FinishToFutureTest extends ClosingFutureTest {
-
-    public void testFinishToFuture_throwsIfCalledTwice() throws Exception {
-      ClosingFuture<Closeable> closingFuture =
-          ClosingFuture.submit(
-              new ClosingCallable<Closeable>() {
-                @Override
-                public Closeable call(DeferredCloser closer) throws Exception {
-                  return closer.eventuallyClose(mockCloseable, executor);
-                }
-              },
-              executor);
-      FluentFuture<Closeable> unused = closingFuture.finishToFuture();
-      try {
-        FluentFuture<Closeable> unused2 = closingFuture.finishToFuture();
-        fail("should have thrown");
-      } catch (IllegalStateException expected) {
-      }
-    }
-
-    public void testFinishToFuture_throwsAfterCallingFinishToValueAndCloser() throws Exception {
-      ClosingFuture<Closeable> closingFuture =
-          ClosingFuture.submit(
-              new ClosingCallable<Closeable>() {
-                @Override
-                public Closeable call(DeferredCloser closer) throws Exception {
-                  return closer.eventuallyClose(mockCloseable, executor);
-                }
-              },
-              executor);
-      closingFuture.finishToValueAndCloser(new NoOpValueAndCloserConsumer<>(), directExecutor());
-      try {
-        FluentFuture<Closeable> unused = closingFuture.finishToFuture();
-        fail("should have thrown");
-      } catch (IllegalStateException expected) {
-      }
-    }
-
-    public void testFinishToFuture_preventsFurtherDerivation() {
-      ClosingFuture<String> closingFuture = ClosingFuture.from(immediateFuture("value1"));
-      FluentFuture<String> unused = closingFuture.finishToFuture();
-      assertDerivingThrowsIllegalStateException(closingFuture);
-    }
-
-    @Override
-    <T> T getFinalValue(ClosingFuture<T> closingFuture) throws ExecutionException {
-      return getUninterruptibly(closingFuture.finishToFuture());
-    }
-
-    @Override
-    void assertFinallyFailsWithException(ClosingFuture<?> closingFuture) {
-      assertThatFutureFailsWithException(closingFuture.finishToFuture());
-    }
-
-    @Override
-    void assertBecomesCanceled(ClosingFuture<?> closingFuture) throws ExecutionException {
-      assertThatFutureBecomesCancelled(closingFuture.finishToFuture());
-    }
-
-    @Override
-    void cancelFinalStepAndWait(ClosingFuture<TestCloseable> closingFuture) {
-      assertThat(closingFuture.finishToFuture().cancel(false)).isTrue();
-      waitUntilClosed(closingFuture);
-      futureCancelled.countDown();
-    }
-  }
-
-  /**
-   * Tests for {@link ClosingFuture} that exercise {@link
-   * ClosingFuture#finishToValueAndCloser(ValueAndCloserConsumer, Executor)}.
-   */
-
-  public static class FinishToValueAndCloserTest extends ClosingFutureTest {
-
-    private final ExecutorService finishToValueAndCloserExecutor = newSingleThreadExecutor();
-    private volatile ValueAndCloser<?> valueAndCloser;
-
-    @Override
-    protected void tearDown() throws Exception {
-      super.tearDown();
-      assertWithMessage("finishToValueAndCloserExecutor was shut down")
-          .that(shutdownAndAwaitTermination(finishToValueAndCloserExecutor, 10, SECONDS))
-          .isTrue();
-    }
-
-    public void testFinishToValueAndCloser_throwsIfCalledTwice() throws Exception {
-      ClosingFuture<Closeable> closingFuture =
-          ClosingFuture.submit(
-              new ClosingCallable<Closeable>() {
-                @Override
-                public Closeable call(DeferredCloser closer) throws Exception {
-                  return closer.eventuallyClose(mockCloseable, executor);
-                }
-              },
-              executor);
-      closingFuture.finishToValueAndCloser(
-          new NoOpValueAndCloserConsumer<>(), finishToValueAndCloserExecutor);
-      try {
-        closingFuture.finishToValueAndCloser(
-            new NoOpValueAndCloserConsumer<>(), finishToValueAndCloserExecutor);
-        fail("should have thrown");
-      } catch (IllegalStateException expected) {
-      }
-    }
-
-    public void testFinishToValueAndCloser_throwsAfterCallingFinishToFuture() throws Exception {
-      ClosingFuture<Closeable> closingFuture =
-          ClosingFuture.submit(
-              new ClosingCallable<Closeable>() {
-                @Override
-                public Closeable call(DeferredCloser closer) throws Exception {
-                  return closer.eventuallyClose(mockCloseable, executor);
-                }
-              },
-              executor);
-      FluentFuture<Closeable> unused = closingFuture.finishToFuture();
-      try {
-        closingFuture.finishToValueAndCloser(
-            new NoOpValueAndCloserConsumer<>(), finishToValueAndCloserExecutor);
-        fail("should have thrown");
-      } catch (IllegalStateException expected) {
-      }
-    }
-
-    @Override
-    <T> T getFinalValue(ClosingFuture<T> closingFuture) throws ExecutionException {
-      return finishToValueAndCloser(closingFuture).get();
-    }
-
-    @Override
-    void assertFinallyFailsWithException(ClosingFuture<?> closingFuture) {
-      assertThatFutureFailsWithException(closingFuture.statusFuture());
-      ValueAndCloser<?> valueAndCloser = finishToValueAndCloser(closingFuture);
-      try {
-        valueAndCloser.get();
-        fail();
-      } catch (ExecutionException expected) {
-        assertThat(expected).hasCauseThat().isSameInstanceAs(exception);
-      }
-      valueAndCloser.closeAsync();
-    }
-
-    @Override
-    void assertBecomesCanceled(ClosingFuture<?> closingFuture) throws ExecutionException {
-      assertThatFutureBecomesCancelled(closingFuture.statusFuture());
-    }
-
-    @Override
-    void waitUntilClosed(ClosingFuture<?> closingFuture) {
-      if (valueAndCloser != null) {
-        valueAndCloser.closeAsync();
-      }
-      super.waitUntilClosed(closingFuture);
-    }
-
-    @Override
-    void cancelFinalStepAndWait(ClosingFuture<TestCloseable> closingFuture) {
-      assertThat(closingFuture.cancel(false)).isTrue();
-      ValueAndCloser<?> unused = finishToValueAndCloser(closingFuture);
-      waitUntilClosed(closingFuture);
-      futureCancelled.countDown();
-    }
-
-    private <V> ValueAndCloser<V> finishToValueAndCloser(ClosingFuture<V> closingFuture) {
-      final CountDownLatch valueAndCloserSet = new CountDownLatch(1);
-      closingFuture.finishToValueAndCloser(
-          new ValueAndCloserConsumer<V>() {
-            @Override
-            public void accept(ValueAndCloser<V> valueAndCloser) {
-              FinishToValueAndCloserTest.this.valueAndCloser = valueAndCloser;
-              valueAndCloserSet.countDown();
-            }
-          },
-          finishToValueAndCloserExecutor);
-      assertWithMessage("valueAndCloser was set")
-          .that(awaitUninterruptibly(valueAndCloserSet, 10, SECONDS))
-          .isTrue();
-      @SuppressWarnings("unchecked")
-      ValueAndCloser<V> valueAndCloserWithType = (ValueAndCloser<V>) valueAndCloser;
-      return valueAndCloserWithType;
-    }
-  }
-
   void assertThatFutureFailsWithException(Future<?> future) {
     try {
       getUninterruptibly(future);
@@ -1822,7 +1637,7 @@ void assertThatFutureFailsWithException(Future<?> future) {
     }
   }
 
-  private static void assertThatFutureBecomesCancelled(Future<?> future) throws ExecutionException {
+  static void assertThatFutureBecomesCancelled(Future<?> future) throws ExecutionException {
     try {
       getUninterruptibly(future);
       fail("Expected future to be canceled: " + future);
@@ -1989,7 +1804,7 @@ void awaitReturned() {
     }
   }
 
-  private static final class NoOpValueAndCloserConsumer<V> implements ValueAndCloserConsumer<V> {
+  static final class NoOpValueAndCloserConsumer<V> implements ValueAndCloserConsumer<V> {
     @Override
     public void accept(ValueAndCloser<V> valueAndCloser) {}
   }
diff --git a/android/guava-tests/test/com/google/common/util/concurrent/AbstractExecutionThreadServiceTest.java b/android/guava-tests/test/com/google/common/util/concurrent/AbstractExecutionThreadServiceTest.java
index 557fc0b5f2fe..9b3f0f86757f 100644
--- a/android/guava-tests/test/com/google/common/util/concurrent/AbstractExecutionThreadServiceTest.java
+++ b/android/guava-tests/test/com/google/common/util/concurrent/AbstractExecutionThreadServiceTest.java
@@ -68,7 +68,6 @@ protected final void tearDown() {
         thrownByExecutionThread);
   }
 
-
   public void testServiceStartStop() throws Exception {
     WaitOnRunService service = new WaitOnRunService();
     assertFalse(service.startUpCalled);
@@ -85,7 +84,6 @@ public void testServiceStartStop() throws Exception {
     executionThread.join();
   }
 
-
   public void testServiceStopIdempotence() throws Exception {
     WaitOnRunService service = new WaitOnRunService();
 
@@ -102,7 +100,6 @@ public void testServiceStopIdempotence() throws Exception {
     executionThread.join();
   }
 
-
   public void testServiceExitingOnItsOwn() throws Exception {
     WaitOnRunService service = new WaitOnRunService();
     service.expectedShutdownState = Service.State.RUNNING;
@@ -173,7 +170,6 @@ protected Executor executor() {
     }
   }
 
-
   public void testServiceThrowOnStartUp() throws Exception {
     ThrowOnStartUpService service = new ThrowOnStartUpService();
     assertFalse(service.startUpCalled);
@@ -212,7 +208,6 @@ protected Executor executor() {
     }
   }
 
-
   public void testServiceThrowOnRun() throws Exception {
     ThrowOnRunService service = new ThrowOnRunService();
 
@@ -229,7 +224,6 @@ public void testServiceThrowOnRun() throws Exception {
     assertEquals(Service.State.FAILED, service.state());
   }
 
-
   public void testServiceThrowOnRunAndThenAgainOnShutDown() throws Exception {
     ThrowOnRunService service = new ThrowOnRunService();
     service.throwOnShutDown = true;
@@ -271,7 +265,6 @@ protected Executor executor() {
     }
   }
 
-
   public void testServiceThrowOnShutDown() throws Exception {
     ThrowOnShutDown service = new ThrowOnShutDown();
 
@@ -331,7 +324,6 @@ public void execute(Runnable command) {}
     protected void run() throws Exception {}
   }
 
-
   public void testStopWhileStarting_runNotCalled() throws Exception {
     final CountDownLatch started = new CountDownLatch(1);
     FakeService service =
@@ -361,7 +353,6 @@ public void testStop_noStart() {
     assertEquals(0, service.shutdownCalled);
   }
 
-
   public void testDefaultService() throws InterruptedException {
     WaitOnRunService service = new WaitOnRunService();
     service.startAsync().awaitRunning();
diff --git a/android/guava-tests/test/com/google/common/util/concurrent/AbstractFutureBenchmarks.java b/android/guava-tests/test/com/google/common/util/concurrent/AbstractFutureBenchmarks.java
index bf70aac25e72..ed5e6a96db0f 100644
--- a/android/guava-tests/test/com/google/common/util/concurrent/AbstractFutureBenchmarks.java
+++ b/android/guava-tests/test/com/google/common/util/concurrent/AbstractFutureBenchmarks.java
@@ -25,7 +25,7 @@
 import java.util.concurrent.TimeUnit;
 import java.util.concurrent.TimeoutException;
 import java.util.concurrent.locks.AbstractQueuedSynchronizer;
-import org.checkerframework.checker.nullness.compatqual.NullableDecl;
+import javax.annotation.CheckForNull;
 
 /** Utilities for the AbstractFutureBenchmarks */
 final class AbstractFutureBenchmarks {
@@ -218,7 +218,7 @@ public void addListener(Runnable listener, Executor exec) {
      * @return true if the state was successfully changed.
      */
     @CanIgnoreReturnValue
-    protected boolean set(@NullableDecl V value) {
+    protected boolean set(@CheckForNull V value) {
       boolean result = sync.set(value);
       if (result) {
         executionList.execute();
@@ -360,7 +360,7 @@ boolean wasInterrupted() {
       }
 
       /** Transition to the COMPLETED state and set the value. */
-      boolean set(@NullableDecl V v) {
+      boolean set(@CheckForNull V v) {
         return complete(v, null, COMPLETED);
       }
 
@@ -384,7 +384,7 @@ boolean cancel(boolean interrupt) {
        * @param t the exception to set as the result of the computation.
        * @param finalState the state to transition to.
        */
-      private boolean complete(@NullableDecl V v, @NullableDecl Throwable t, int finalState) {
+      private boolean complete(@CheckForNull V v, @CheckForNull Throwable t, int finalState) {
         boolean doCompletion = compareAndSetState(RUNNING, COMPLETING);
         if (doCompletion) {
           // If this thread successfully transitioned to COMPLETING, set the value
@@ -406,7 +406,7 @@ private boolean complete(@NullableDecl V v, @NullableDecl Throwable t, int final
     }
 
     static final CancellationException cancellationExceptionWithCause(
-        @NullableDecl String message, @NullableDecl Throwable cause) {
+        @CheckForNull String message, @CheckForNull Throwable cause) {
       CancellationException exception = new CancellationException(message);
       exception.initCause(cause);
       return exception;
diff --git a/android/guava-tests/test/com/google/common/util/concurrent/AbstractFutureCancellationCauseTest.java b/android/guava-tests/test/com/google/common/util/concurrent/AbstractFutureCancellationCauseTest.java
index 6c921b5b67d5..9aee78029f08 100644
--- a/android/guava-tests/test/com/google/common/util/concurrent/AbstractFutureCancellationCauseTest.java
+++ b/android/guava-tests/test/com/google/common/util/concurrent/AbstractFutureCancellationCauseTest.java
@@ -30,6 +30,7 @@
 import junit.framework.TestCase;
 
 /** Tests for {@link AbstractFuture} with the cancellation cause system property set */
+@AndroidIncompatible // custom classloading
 
 public class AbstractFutureCancellationCauseTest extends TestCase {
 
diff --git a/android/guava-tests/test/com/google/common/util/concurrent/AbstractFutureTest.java b/android/guava-tests/test/com/google/common/util/concurrent/AbstractFutureTest.java
index e55a31e725de..dc020fb20a0d 100644
--- a/android/guava-tests/test/com/google/common/util/concurrent/AbstractFutureTest.java
+++ b/android/guava-tests/test/com/google/common/util/concurrent/AbstractFutureTest.java
@@ -52,7 +52,6 @@
  *
  * @author Brian Stoler
  */
-
 public class AbstractFutureTest extends TestCase {
   public void testSuccess() throws ExecutionException, InterruptedException {
     final Object value = new Object();
@@ -292,6 +291,7 @@ public String pendingToString() {
    * derived from observing how much time actually passed for various operations.
    */
   @SuppressWarnings({"DeprecatedThreadMethods", "ThreadPriorityCheck"})
+  @AndroidIncompatible // Thread.suspend
   public void testToString_delayedTimeout() throws Exception {
     TimedWaiterThread thread =
         new TimedWaiterThread(new AbstractFuture<Object>() {}, 2, TimeUnit.SECONDS);
diff --git a/android/guava-tests/test/com/google/common/util/concurrent/AbstractIdleServiceTest.java b/android/guava-tests/test/com/google/common/util/concurrent/AbstractIdleServiceTest.java
index 7cad8b0fa712..2df5a4f3afa8 100644
--- a/android/guava-tests/test/com/google/common/util/concurrent/AbstractIdleServiceTest.java
+++ b/android/guava-tests/test/com/google/common/util/concurrent/AbstractIdleServiceTest.java
@@ -36,7 +36,6 @@ public class AbstractIdleServiceTest extends TestCase {
 
   // Functional tests using real thread. We only verify publicly visible state.
   // Interaction assertions are done by the single-threaded unit tests.
-
   public static class FunctionalTest extends TestCase {
 
     private static class DefaultService extends AbstractIdleService {
diff --git a/android/guava-tests/test/com/google/common/util/concurrent/AbstractScheduledServiceTest.java b/android/guava-tests/test/com/google/common/util/concurrent/AbstractScheduledServiceTest.java
index 158520b932ed..a05a838692b3 100644
--- a/android/guava-tests/test/com/google/common/util/concurrent/AbstractScheduledServiceTest.java
+++ b/android/guava-tests/test/com/google/common/util/concurrent/AbstractScheduledServiceTest.java
@@ -19,8 +19,11 @@
 import static com.google.common.truth.Truth.assertThat;
 import static com.google.common.util.concurrent.AbstractScheduledService.Scheduler.newFixedDelaySchedule;
 import static com.google.common.util.concurrent.MoreExecutors.directExecutor;
+import static java.util.concurrent.TimeUnit.MILLISECONDS;
+import static java.util.concurrent.TimeUnit.NANOSECONDS;
 import static java.util.concurrent.TimeUnit.SECONDS;
 
+import com.google.common.util.concurrent.AbstractScheduledService.Cancellable;
 import com.google.common.util.concurrent.AbstractScheduledService.Scheduler;
 import com.google.common.util.concurrent.Service.State;
 import com.google.common.util.concurrent.testing.TestingExecutors;
@@ -28,6 +31,7 @@
 import java.util.concurrent.CancellationException;
 import java.util.concurrent.CountDownLatch;
 import java.util.concurrent.CyclicBarrier;
+import java.util.concurrent.Delayed;
 import java.util.concurrent.Executors;
 import java.util.concurrent.Future;
 import java.util.concurrent.ScheduledExecutorService;
@@ -45,10 +49,9 @@
  *
  * @author Luke Sandberg
  */
-
 public class AbstractScheduledServiceTest extends TestCase {
 
-  volatile Scheduler configuration = newFixedDelaySchedule(0, 10, TimeUnit.MILLISECONDS);
+  volatile Scheduler configuration = newFixedDelaySchedule(0, 10, MILLISECONDS);
   volatile ScheduledFuture<?> future = null;
 
   volatile boolean atFixedRateCalled = false;
@@ -111,7 +114,7 @@ public void testFailOnExceptionFromStartUp() {
       service.startAsync().awaitRunning();
       fail();
     } catch (IllegalStateException e) {
-      assertEquals(service.startUpException, e.getCause());
+      assertThat(e).hasCauseThat().isEqualTo(service.startUpException);
     }
     assertEquals(0, service.numberOfTimesRunCalled.get());
     assertEquals(Service.State.FAILED, service.state());
@@ -154,7 +157,7 @@ public void testFailOnExceptionFromShutDown() throws Exception {
       service.awaitTerminated();
       fail();
     } catch (IllegalStateException e) {
-      assertEquals(service.shutDownException, e.getCause());
+      assertThat(e).hasCauseThat().isEqualTo(service.shutDownException);
     }
     assertEquals(Service.State.FAILED, service.state());
   }
@@ -206,7 +209,7 @@ protected ScheduledExecutorService executor() {
 
           @Override
           protected Scheduler scheduler() {
-            return newFixedDelaySchedule(0, 1, TimeUnit.MILLISECONDS);
+            return newFixedDelaySchedule(0, 1, MILLISECONDS);
           }
         };
 
@@ -215,7 +218,7 @@ protected Scheduler scheduler() {
     service.awaitRunning();
     service.stopAsync();
     service.awaitTerminated();
-    assertTrue(executor.get().awaitTermination(100, TimeUnit.MILLISECONDS));
+    assertTrue(executor.get().awaitTermination(100, MILLISECONDS));
   }
 
   public void testDefaultExecutorIsShutdownWhenServiceFails() throws Exception {
@@ -238,7 +241,7 @@ protected ScheduledExecutorService executor() {
 
           @Override
           protected Scheduler scheduler() {
-            return newFixedDelaySchedule(0, 1, TimeUnit.MILLISECONDS);
+            return newFixedDelaySchedule(0, 1, MILLISECONDS);
           }
         };
 
@@ -248,7 +251,7 @@ protected Scheduler scheduler() {
     } catch (IllegalStateException expected) {
     }
 
-    assertTrue(executor.get().awaitTermination(100, TimeUnit.MILLISECONDS));
+    assertTrue(executor.get().awaitTermination(100, MILLISECONDS));
   }
 
   public void testSchedulerOnlyCalledOnce() throws Exception {
@@ -275,7 +278,7 @@ public void testTimeout() {
         new AbstractScheduledService() {
           @Override
           protected Scheduler scheduler() {
-            return Scheduler.newFixedDelaySchedule(0, 1, TimeUnit.NANOSECONDS);
+            return Scheduler.newFixedDelaySchedule(0, 1, NANOSECONDS);
           }
 
           @Override
@@ -292,7 +295,7 @@ protected String serviceName() {
           }
         };
     try {
-      service.startAsync().awaitRunning(1, TimeUnit.MILLISECONDS);
+      service.startAsync().awaitRunning(1, MILLISECONDS);
       fail("Expected timeout");
     } catch (TimeoutException e) {
       assertThat(e)
@@ -364,9 +367,9 @@ protected Scheduler scheduler() {
   public static class SchedulerTest extends TestCase {
     // These constants are arbitrary and just used to make sure that the correct method is called
     // with the correct parameters.
-    private static final int initialDelay = 10;
-    private static final int delay = 20;
-    private static final TimeUnit unit = TimeUnit.MILLISECONDS;
+    private static final int INITIAL_DELAY = 10;
+    private static final int DELAY = 20;
+    private static final TimeUnit UNIT = MILLISECONDS;
 
     // Unique runnable object used for comparison.
     final Runnable testRunnable =
@@ -380,23 +383,23 @@ private void assertSingleCallWithCorrectParameters(
         Runnable command, long initialDelay, long delay, TimeUnit unit) {
       assertFalse(called); // only called once.
       called = true;
-      assertEquals(SchedulerTest.initialDelay, initialDelay);
-      assertEquals(SchedulerTest.delay, delay);
-      assertEquals(SchedulerTest.unit, unit);
+      assertEquals(INITIAL_DELAY, initialDelay);
+      assertEquals(DELAY, delay);
+      assertEquals(UNIT, unit);
       assertEquals(testRunnable, command);
     }
 
     public void testFixedRateSchedule() {
-      Scheduler schedule = Scheduler.newFixedRateSchedule(initialDelay, delay, unit);
-      Future<?> unused =
+      Scheduler schedule = Scheduler.newFixedRateSchedule(INITIAL_DELAY, DELAY, UNIT);
+      Cancellable unused =
           schedule.schedule(
               null,
               new ScheduledThreadPoolExecutor(1) {
                 @Override
                 public ScheduledFuture<?> scheduleAtFixedRate(
                     Runnable command, long initialDelay, long period, TimeUnit unit) {
-                  assertSingleCallWithCorrectParameters(command, initialDelay, delay, unit);
-                  return null;
+                  assertSingleCallWithCorrectParameters(command, initialDelay, period, unit);
+                  return new ThrowingScheduledFuture<>();
                 }
               },
               testRunnable);
@@ -404,8 +407,8 @@ public ScheduledFuture<?> scheduleAtFixedRate(
     }
 
     public void testFixedDelaySchedule() {
-      Scheduler schedule = newFixedDelaySchedule(initialDelay, delay, unit);
-      Future<?> unused =
+      Scheduler schedule = newFixedDelaySchedule(INITIAL_DELAY, DELAY, UNIT);
+      Cancellable unused =
           schedule.schedule(
               null,
               new ScheduledThreadPoolExecutor(10) {
@@ -413,13 +416,30 @@ public void testFixedDelaySchedule() {
                 public ScheduledFuture<?> scheduleWithFixedDelay(
                     Runnable command, long initialDelay, long delay, TimeUnit unit) {
                   assertSingleCallWithCorrectParameters(command, initialDelay, delay, unit);
-                  return null;
+                  return new ThrowingScheduledFuture<>();
                 }
               },
               testRunnable);
       assertTrue(called);
     }
 
+    private static final class ThrowingScheduledFuture<V> extends ForwardingFuture<V>
+        implements ScheduledFuture<V> {
+      @Override
+      protected Future<V> delegate() {
+        throw new UnsupportedOperationException("test should not care about this");
+      }
+
+      @Override
+      public long getDelay(TimeUnit unit) {
+        throw new UnsupportedOperationException("test should not care about this");
+      }
+
+      @Override
+      public int compareTo(Delayed other) {
+        throw new UnsupportedOperationException("test should not care about this");
+      }
+    }
 
     public void testFixedDelayScheduleFarFuturePotentiallyOverflowingScheduleIsNeverReached()
         throws Exception {
@@ -441,7 +461,6 @@ protected Scheduler scheduler() {
       service.awaitTerminated();
     }
 
-
     public void testCustomSchedulerFarFuturePotentiallyOverflowingScheduleIsNeverReached()
         throws Exception {
       TestAbstractScheduledCustomService service =
@@ -467,17 +486,16 @@ protected Schedule getNextSchedule() throws Exception {
       service.awaitTerminated();
     }
 
-    private class TestCustomScheduler extends AbstractScheduledService.CustomScheduler {
+    private static class TestCustomScheduler extends AbstractScheduledService.CustomScheduler {
       public AtomicInteger scheduleCounter = new AtomicInteger(0);
 
       @Override
       protected Schedule getNextSchedule() throws Exception {
         scheduleCounter.incrementAndGet();
-        return new Schedule(0, TimeUnit.SECONDS);
+        return new Schedule(0, SECONDS);
       }
     }
 
-
     public void testCustomSchedule_startStop() throws Exception {
       final CyclicBarrier firstBarrier = new CyclicBarrier(2);
       final CyclicBarrier secondBarrier = new CyclicBarrier(2);
@@ -497,7 +515,7 @@ public void run() {
             }
           };
       TestCustomScheduler scheduler = new TestCustomScheduler();
-      Future<?> future = scheduler.schedule(null, Executors.newScheduledThreadPool(10), task);
+      Cancellable future = scheduler.schedule(null, Executors.newScheduledThreadPool(10), task);
       firstBarrier.await();
       assertEquals(1, scheduler.scheduleCounter.get());
       secondBarrier.await();
@@ -508,7 +526,6 @@ public void run() {
       future.cancel(false);
     }
 
-
     public void testCustomSchedulerServiceStop() throws Exception {
       TestAbstractScheduledCustomService service = new TestAbstractScheduledCustomService();
       service.startAsync().awaitRunning();
@@ -518,11 +535,10 @@ public void testCustomSchedulerServiceStop() throws Exception {
       service.secondBarrier.await();
       service.awaitTerminated();
       // Sleep for a while just to ensure that our task wasn't called again.
-      Thread.sleep(unit.toMillis(3 * delay));
+      Thread.sleep(UNIT.toMillis(3 * DELAY));
       assertEquals(1, service.numIterations.get());
     }
 
-
     public void testCustomScheduler_deadlock() throws InterruptedException, BrokenBarrierException {
       final CyclicBarrier inGetNextSchedule = new CyclicBarrier(2);
       // This will flakily deadlock, so run it multiple times to increase the flake likelihood
@@ -542,7 +558,7 @@ protected Schedule getNextSchedule() throws Exception {
                       Thread.yield();
                       throw new RuntimeException("boom");
                     }
-                    return new Schedule(0, TimeUnit.NANOSECONDS);
+                    return new Schedule(0, NANOSECONDS);
                   }
                 };
               }
@@ -553,7 +569,6 @@ protected Schedule getNextSchedule() throws Exception {
       }
     }
 
-
     public void testBig() throws Exception {
       TestAbstractScheduledCustomService service =
           new TestAbstractScheduledCustomService() {
@@ -564,7 +579,7 @@ protected Scheduler scheduler() {
                 protected Schedule getNextSchedule() throws Exception {
                   // Explicitly yield to increase the probability of a pathological scheduling.
                   Thread.yield();
-                  return new Schedule(0, TimeUnit.SECONDS);
+                  return new Schedule(0, SECONDS);
                 }
               };
             }
@@ -607,13 +622,12 @@ protected Scheduler scheduler() {
         return new CustomScheduler() {
           @Override
           protected Schedule getNextSchedule() throws Exception {
-            return new Schedule(delay, unit);
+            return new Schedule(DELAY, UNIT);
           }
         };
       }
     }
 
-
     public void testCustomSchedulerFailure() throws Exception {
       TestFailingCustomScheduledService service = new TestFailingCustomScheduledService();
       service.startAsync().awaitRunning();
@@ -624,7 +638,7 @@ public void testCustomSchedulerFailure() throws Exception {
       }
       Thread.sleep(1000);
       try {
-        service.stopAsync().awaitTerminated(100, TimeUnit.SECONDS);
+        service.stopAsync().awaitTerminated(100, SECONDS);
         fail();
       } catch (IllegalStateException e) {
         assertEquals(State.FAILED, service.state());
@@ -657,7 +671,7 @@ protected Schedule getNextSchedule() throws Exception {
             if (numIterations.get() > 2) {
               throw new IllegalStateException("Failed");
             }
-            return new Schedule(delay, unit);
+            return new Schedule(DELAY, UNIT);
           }
         };
       }
diff --git a/android/guava-tests/test/com/google/common/util/concurrent/AbstractServiceTest.java b/android/guava-tests/test/com/google/common/util/concurrent/AbstractServiceTest.java
index e3c22a8673df..5f4210621ea8 100644
--- a/android/guava-tests/test/com/google/common/util/concurrent/AbstractServiceTest.java
+++ b/android/guava-tests/test/com/google/common/util/concurrent/AbstractServiceTest.java
@@ -330,7 +330,6 @@ protected void doStop() {
     }
   }
 
-
   public void testAwaitTerminated() throws Exception {
     final NoOpService service = new NoOpService();
     Thread waiter =
@@ -348,7 +347,6 @@ public void run() {
     assertFalse(waiter.isAlive());
   }
 
-
   public void testAwaitTerminated_FailedService() throws Exception {
     final ManualSwitchedService service = new ManualSwitchedService();
     final AtomicReference<Throwable> exception = Atomics.newReference();
@@ -376,7 +374,6 @@ public void run() {
     assertThat(exception.get()).hasCauseThat().isEqualTo(EXCEPTION);
   }
 
-
   public void testThreadedServiceStartAndWaitStopAndWait() throws Throwable {
     ThreadedService service = new ThreadedService();
     RecordingListener listener = RecordingListener.record(service);
@@ -394,7 +391,6 @@ public void testThreadedServiceStartAndWaitStopAndWait() throws Throwable {
         listener.getStateHistory());
   }
 
-
   public void testThreadedServiceStopIdempotence() throws Throwable {
     ThreadedService service = new ThreadedService();
 
@@ -410,7 +406,6 @@ public void testThreadedServiceStopIdempotence() throws Throwable {
     throwIfSet(thrownByExecutionThread);
   }
 
-
   public void testThreadedServiceStopIdempotenceAfterWait() throws Throwable {
     ThreadedService service = new ThreadedService();
 
@@ -428,7 +423,6 @@ public void testThreadedServiceStopIdempotenceAfterWait() throws Throwable {
     throwIfSet(thrownByExecutionThread);
   }
 
-
   public void testThreadedServiceStopIdempotenceDoubleWait() throws Throwable {
     ThreadedService service = new ThreadedService();
 
@@ -661,7 +655,6 @@ public void testFailureCause_throwsIfNotFailed() {
     }
   }
 
-
   public void testAddListenerAfterFailureDoesntCauseDeadlock() throws InterruptedException {
     final StartFailingService service = new StartFailingService();
     service.startAsync();
@@ -681,7 +674,6 @@ public void run() {
     assertFalse(thread + " is deadlocked", thread.isAlive());
   }
 
-
   public void testListenerDoesntDeadlockOnStartAndWaitFromRunning() throws Exception {
     final NoOpThreadedService service = new NoOpThreadedService();
     service.addListener(
@@ -696,7 +688,6 @@ public void running() {
     service.stopAsync();
   }
 
-
   public void testListenerDoesntDeadlockOnStopAndWaitFromTerminated() throws Exception {
     final NoOpThreadedService service = new NoOpThreadedService();
     service.addListener(
diff --git a/android/guava-tests/test/com/google/common/util/concurrent/AtomicDoubleArrayTest.java b/android/guava-tests/test/com/google/common/util/concurrent/AtomicDoubleArrayTest.java
index 70c186d345da..5bb1cb74e7cf 100644
--- a/android/guava-tests/test/com/google/common/util/concurrent/AtomicDoubleArrayTest.java
+++ b/android/guava-tests/test/com/google/common/util/concurrent/AtomicDoubleArrayTest.java
@@ -181,7 +181,6 @@ public void testCompareAndSet() {
   }
 
   /** compareAndSet in one thread enables another waiting for value to succeed */
-
   public void testCompareAndSetInMultipleThreads() throws InterruptedException {
     final AtomicDoubleArray a = new AtomicDoubleArray(1);
     a.set(0, 1.0);
@@ -294,7 +293,6 @@ public void realRun() {
    * Multiple threads using same array of counters successfully update a number of times equal to
    * total count
    */
-
   public void testCountingInMultipleThreads() throws InterruptedException {
     final AtomicDoubleArray aa = new AtomicDoubleArray(SIZE);
     for (int i = 0; i < SIZE; i++) {
diff --git a/android/guava-tests/test/com/google/common/util/concurrent/AtomicDoubleTest.java b/android/guava-tests/test/com/google/common/util/concurrent/AtomicDoubleTest.java
index fe68e009952f..fc06fd433e11 100644
--- a/android/guava-tests/test/com/google/common/util/concurrent/AtomicDoubleTest.java
+++ b/android/guava-tests/test/com/google/common/util/concurrent/AtomicDoubleTest.java
@@ -13,7 +13,6 @@
 
 package com.google.common.util.concurrent;
 
-
 /** Unit test for {@link AtomicDouble}. */
 public class AtomicDoubleTest extends JSR166TestCase {
 
@@ -97,7 +96,6 @@ public void testCompareAndSet() {
   }
 
   /** compareAndSet in one thread enables another waiting for value to succeed */
-
   public void testCompareAndSetInMultipleThreads() throws Exception {
     final AtomicDouble at = new AtomicDouble(1.0);
     Thread t =
diff --git a/android/guava-tests/test/com/google/common/util/concurrent/AtomicLongMapBasherTest.java b/android/guava-tests/test/com/google/common/util/concurrent/AtomicLongMapBasherTest.java
index 4765825855ba..b1e741a68118 100644
--- a/android/guava-tests/test/com/google/common/util/concurrent/AtomicLongMapBasherTest.java
+++ b/android/guava-tests/test/com/google/common/util/concurrent/AtomicLongMapBasherTest.java
@@ -16,13 +16,15 @@
 
 package com.google.common.util.concurrent;
 
+import static java.util.concurrent.TimeUnit.SECONDS;
+
 import com.google.common.annotations.GwtIncompatible;
+import java.util.ArrayList;
 import java.util.Random;
+import java.util.concurrent.Callable;
 import java.util.concurrent.ExecutorService;
 import java.util.concurrent.Executors;
 import java.util.concurrent.Future;
-import java.util.concurrent.TimeUnit;
-import java.util.concurrent.atomic.AtomicLong;
 import junit.framework.TestCase;
 
 /**
@@ -31,29 +33,27 @@
  * @author mike nonemacher
  */
 @GwtIncompatible // threads
-
 public class AtomicLongMapBasherTest extends TestCase {
   private final Random random = new Random(301);
 
-  public void testModify_basher() throws InterruptedException {
+  public void testModify_basher() throws Exception {
     int nTasks = 3000;
     int nThreads = 100;
     final int getsPerTask = 1000;
     final int deltaRange = 10000;
     final String key = "key";
 
-    final AtomicLong sum = new AtomicLong();
     final AtomicLongMap<String> map = AtomicLongMap.create();
 
     ExecutorService threadPool = Executors.newFixedThreadPool(nThreads);
+    ArrayList<Future<Long>> futures = new ArrayList<>();
     for (int i = 0; i < nTasks; i++) {
-      @SuppressWarnings("unused") // https://errorprone.info/bugpattern/FutureReturnValueIgnored
-      Future<?> possiblyIgnoredError =
+      futures.add(
           threadPool.submit(
-              new Runnable() {
+              new Callable<Long>() {
                 @Override
-                public void run() {
-                  int threadSum = 0;
+                public Long call() {
+                  long threadSum = 0;
                   for (int j = 0; j < getsPerTask; j++) {
                     long delta = random.nextInt(deltaRange);
                     int behavior = random.nextInt(10);
@@ -106,14 +106,16 @@ public void run() {
                         throw new AssertionError();
                     }
                   }
-                  sum.addAndGet(threadSum);
+                  return threadSum;
                 }
-              });
+              }));
     }
-
     threadPool.shutdown();
-    assertTrue(threadPool.awaitTermination(300, TimeUnit.SECONDS));
-
-    assertEquals(sum.get(), map.get(key));
+    assertTrue(threadPool.awaitTermination(300, SECONDS));
+    long sum = 0;
+    for (Future<Long> f : futures) {
+      sum += f.get();
+    }
+    assertEquals(sum, map.get(key));
   }
 }
diff --git a/android/guava-tests/test/com/google/common/util/concurrent/AtomicLongMapTest.java b/android/guava-tests/test/com/google/common/util/concurrent/AtomicLongMapTest.java
index 587a4ec21d72..878ea5ec87ac 100644
--- a/android/guava-tests/test/com/google/common/util/concurrent/AtomicLongMapTest.java
+++ b/android/guava-tests/test/com/google/common/util/concurrent/AtomicLongMapTest.java
@@ -52,7 +52,7 @@ public void testCreate_map() {
     Map<String, Long> in = ImmutableMap.of("1", 1L, "2", 2L, "3", 3L);
     AtomicLongMap<String> map = AtomicLongMap.create(in);
     assertFalse(map.isEmpty());
-    assertSame(3, map.size());
+    assertEquals(3, map.size());
     assertTrue(map.containsKey("1"));
     assertTrue(map.containsKey("2"));
     assertTrue(map.containsKey("3"));
@@ -302,7 +302,7 @@ public void testPutAll() {
     Map<String, Long> in = ImmutableMap.of("1", 1L, "2", 2L, "3", 3L);
     AtomicLongMap<String> map = AtomicLongMap.create();
     assertTrue(map.isEmpty());
-    assertSame(0, map.size());
+    assertEquals(0, map.size());
     assertFalse(map.containsKey("1"));
     assertFalse(map.containsKey("2"));
     assertFalse(map.containsKey("3"));
@@ -312,7 +312,7 @@ public void testPutAll() {
 
     map.putAll(in);
     assertFalse(map.isEmpty());
-    assertSame(3, map.size());
+    assertEquals(3, map.size());
     assertTrue(map.containsKey("1"));
     assertTrue(map.containsKey("2"));
     assertTrue(map.containsKey("3"));
diff --git a/android/guava-tests/test/com/google/common/util/concurrent/ClosingFutureFinishToFutureTest.java b/android/guava-tests/test/com/google/common/util/concurrent/ClosingFutureFinishToFutureTest.java
new file mode 100644
index 000000000000..79288eb2a0a9
--- /dev/null
+++ b/android/guava-tests/test/com/google/common/util/concurrent/ClosingFutureFinishToFutureTest.java
@@ -0,0 +1,94 @@
+/*
+ * Copyright (C) 2017 The Guava Authors
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package com.google.common.util.concurrent;
+
+import static com.google.common.truth.Truth.assertThat;
+import static com.google.common.util.concurrent.Futures.immediateFuture;
+import static com.google.common.util.concurrent.MoreExecutors.directExecutor;
+import static com.google.common.util.concurrent.Uninterruptibles.getUninterruptibly;
+
+import com.google.common.util.concurrent.ClosingFuture.ClosingCallable;
+import com.google.common.util.concurrent.ClosingFuture.DeferredCloser;
+import java.io.Closeable;
+import java.util.concurrent.ExecutionException;
+
+/** Tests for {@link ClosingFuture} that exercise {@link ClosingFuture#finishToFuture()}. */
+public class ClosingFutureFinishToFutureTest extends AbstractClosingFutureTest {
+  public void testFinishToFuture_throwsIfCalledTwice() throws Exception {
+    ClosingFuture<Closeable> closingFuture =
+        ClosingFuture.submit(
+            new ClosingCallable<Closeable>() {
+              @Override
+              public Closeable call(DeferredCloser closer) throws Exception {
+                return closer.eventuallyClose(mockCloseable, executor);
+              }
+            },
+            executor);
+    FluentFuture<Closeable> unused = closingFuture.finishToFuture();
+    try {
+      FluentFuture<Closeable> unused2 = closingFuture.finishToFuture();
+      fail("should have thrown");
+    } catch (IllegalStateException expected) {
+    }
+  }
+
+  public void testFinishToFuture_throwsAfterCallingFinishToValueAndCloser() throws Exception {
+    ClosingFuture<Closeable> closingFuture =
+        ClosingFuture.submit(
+            new ClosingCallable<Closeable>() {
+              @Override
+              public Closeable call(DeferredCloser closer) throws Exception {
+                return closer.eventuallyClose(mockCloseable, executor);
+              }
+            },
+            executor);
+    closingFuture.finishToValueAndCloser(new NoOpValueAndCloserConsumer<>(), directExecutor());
+    try {
+      FluentFuture<Closeable> unused = closingFuture.finishToFuture();
+      fail("should have thrown");
+    } catch (IllegalStateException expected) {
+    }
+  }
+
+  public void testFinishToFuture_preventsFurtherDerivation() {
+    ClosingFuture<String> closingFuture = ClosingFuture.from(immediateFuture("value1"));
+    FluentFuture<String> unused = closingFuture.finishToFuture();
+    assertDerivingThrowsIllegalStateException(closingFuture);
+  }
+
+  @Override
+  <T> T getFinalValue(ClosingFuture<T> closingFuture) throws ExecutionException {
+    return getUninterruptibly(closingFuture.finishToFuture());
+  }
+
+  @Override
+  void assertFinallyFailsWithException(ClosingFuture<?> closingFuture) {
+    assertThatFutureFailsWithException(closingFuture.finishToFuture());
+  }
+
+  @Override
+  void assertBecomesCanceled(ClosingFuture<?> closingFuture) throws ExecutionException {
+    assertThatFutureBecomesCancelled(closingFuture.finishToFuture());
+  }
+
+  @Override
+  void cancelFinalStepAndWait(ClosingFuture<TestCloseable> closingFuture) {
+    assertThat(closingFuture.finishToFuture().cancel(false)).isTrue();
+    waitUntilClosed(closingFuture);
+    futureCancelled.countDown();
+  }
+}
diff --git a/android/guava-tests/test/com/google/common/util/concurrent/ClosingFutureFinishToValueAndCloserTest.java b/android/guava-tests/test/com/google/common/util/concurrent/ClosingFutureFinishToValueAndCloserTest.java
new file mode 100644
index 000000000000..ac3cf556925f
--- /dev/null
+++ b/android/guava-tests/test/com/google/common/util/concurrent/ClosingFutureFinishToValueAndCloserTest.java
@@ -0,0 +1,148 @@
+/*
+ * Copyright (C) 2017 The Guava Authors
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package com.google.common.util.concurrent;
+
+import static com.google.common.truth.Truth.assertThat;
+import static com.google.common.truth.Truth.assertWithMessage;
+import static com.google.common.util.concurrent.MoreExecutors.shutdownAndAwaitTermination;
+import static com.google.common.util.concurrent.Uninterruptibles.awaitUninterruptibly;
+import static java.util.concurrent.Executors.newSingleThreadExecutor;
+import static java.util.concurrent.TimeUnit.SECONDS;
+
+import com.google.common.util.concurrent.ClosingFuture.ClosingCallable;
+import com.google.common.util.concurrent.ClosingFuture.DeferredCloser;
+import com.google.common.util.concurrent.ClosingFuture.ValueAndCloser;
+import com.google.common.util.concurrent.ClosingFuture.ValueAndCloserConsumer;
+import java.io.Closeable;
+import java.util.concurrent.CountDownLatch;
+import java.util.concurrent.ExecutionException;
+import java.util.concurrent.Executor;
+import java.util.concurrent.ExecutorService;
+
+/**
+ * Tests for {@link ClosingFuture} that exercise {@link
+ * ClosingFuture#finishToValueAndCloser(ValueAndCloserConsumer, Executor)}.
+ */
+public class ClosingFutureFinishToValueAndCloserTest extends AbstractClosingFutureTest {
+  private final ExecutorService finishToValueAndCloserExecutor = newSingleThreadExecutor();
+  private volatile ValueAndCloser<?> valueAndCloser;
+
+  @Override
+  protected void tearDown() throws Exception {
+    super.tearDown();
+    assertWithMessage("finishToValueAndCloserExecutor was shut down")
+        .that(shutdownAndAwaitTermination(finishToValueAndCloserExecutor, 10, SECONDS))
+        .isTrue();
+  }
+
+  public void testFinishToValueAndCloser_throwsIfCalledTwice() throws Exception {
+    ClosingFuture<Closeable> closingFuture =
+        ClosingFuture.submit(
+            new ClosingCallable<Closeable>() {
+              @Override
+              public Closeable call(DeferredCloser closer) throws Exception {
+                return closer.eventuallyClose(mockCloseable, executor);
+              }
+            },
+            executor);
+    closingFuture.finishToValueAndCloser(
+        new NoOpValueAndCloserConsumer<>(), finishToValueAndCloserExecutor);
+    try {
+      closingFuture.finishToValueAndCloser(
+          new NoOpValueAndCloserConsumer<>(), finishToValueAndCloserExecutor);
+      fail("should have thrown");
+    } catch (IllegalStateException expected) {
+    }
+  }
+
+  public void testFinishToValueAndCloser_throwsAfterCallingFinishToFuture() throws Exception {
+    ClosingFuture<Closeable> closingFuture =
+        ClosingFuture.submit(
+            new ClosingCallable<Closeable>() {
+              @Override
+              public Closeable call(DeferredCloser closer) throws Exception {
+                return closer.eventuallyClose(mockCloseable, executor);
+              }
+            },
+            executor);
+    FluentFuture<Closeable> unused = closingFuture.finishToFuture();
+    try {
+      closingFuture.finishToValueAndCloser(
+          new NoOpValueAndCloserConsumer<>(), finishToValueAndCloserExecutor);
+      fail("should have thrown");
+    } catch (IllegalStateException expected) {
+    }
+  }
+
+  @Override
+  <T> T getFinalValue(ClosingFuture<T> closingFuture) throws ExecutionException {
+    return finishToValueAndCloser(closingFuture).get();
+  }
+
+  @Override
+  void assertFinallyFailsWithException(ClosingFuture<?> closingFuture) {
+    assertThatFutureFailsWithException(closingFuture.statusFuture());
+    ValueAndCloser<?> valueAndCloser = finishToValueAndCloser(closingFuture);
+    try {
+      valueAndCloser.get();
+      fail();
+    } catch (ExecutionException expected) {
+      assertThat(expected).hasCauseThat().isSameInstanceAs(exception);
+    }
+    valueAndCloser.closeAsync();
+  }
+
+  @Override
+  void assertBecomesCanceled(ClosingFuture<?> closingFuture) throws ExecutionException {
+    assertThatFutureBecomesCancelled(closingFuture.statusFuture());
+  }
+
+  @Override
+  void waitUntilClosed(ClosingFuture<?> closingFuture) {
+    if (valueAndCloser != null) {
+      valueAndCloser.closeAsync();
+    }
+    super.waitUntilClosed(closingFuture);
+  }
+
+  @Override
+  void cancelFinalStepAndWait(ClosingFuture<TestCloseable> closingFuture) {
+    assertThat(closingFuture.cancel(false)).isTrue();
+    ValueAndCloser<?> unused = finishToValueAndCloser(closingFuture);
+    waitUntilClosed(closingFuture);
+    futureCancelled.countDown();
+  }
+
+  private <V> ValueAndCloser<V> finishToValueAndCloser(ClosingFuture<V> closingFuture) {
+    final CountDownLatch valueAndCloserSet = new CountDownLatch(1);
+    closingFuture.finishToValueAndCloser(
+        new ValueAndCloserConsumer<V>() {
+          @Override
+          public void accept(ValueAndCloser<V> valueAndCloser) {
+            ClosingFutureFinishToValueAndCloserTest.this.valueAndCloser = valueAndCloser;
+            valueAndCloserSet.countDown();
+          }
+        },
+        finishToValueAndCloserExecutor);
+    assertWithMessage("valueAndCloser was set")
+        .that(awaitUninterruptibly(valueAndCloserSet, 10, SECONDS))
+        .isTrue();
+    @SuppressWarnings("unchecked")
+    ValueAndCloser<V> valueAndCloserWithType = (ValueAndCloser<V>) valueAndCloser;
+    return valueAndCloserWithType;
+  }
+}
diff --git a/android/guava-tests/test/com/google/common/util/concurrent/CycleDetectingLockFactoryTest.java b/android/guava-tests/test/com/google/common/util/concurrent/CycleDetectingLockFactoryTest.java
index 18e69b10ee39..2b1dd2fa0881 100644
--- a/android/guava-tests/test/com/google/common/util/concurrent/CycleDetectingLockFactoryTest.java
+++ b/android/guava-tests/test/com/google/common/util/concurrent/CycleDetectingLockFactoryTest.java
@@ -442,7 +442,6 @@ public void testDifferentLockFactories_policyExecution() {
     lockD.lock();
   }
 
-
   public void testReentrantLock_tryLock() throws Exception {
     LockingThread thread = new LockingThread(lockA);
     thread.start();
@@ -454,7 +453,6 @@ public void testReentrantLock_tryLock() throws Exception {
     assertTrue(lockA.tryLock());
   }
 
-
   public void testReentrantWriteLock_tryLock() throws Exception {
     LockingThread thread = new LockingThread(writeLockA);
     thread.start();
@@ -468,7 +466,6 @@ public void testReentrantWriteLock_tryLock() throws Exception {
     assertTrue(readLockA.tryLock());
   }
 
-
   public void testReentrantReadLock_tryLock() throws Exception {
     LockingThread thread = new LockingThread(readLockA);
     thread.start();
diff --git a/android/guava-tests/test/com/google/common/util/concurrent/ExecutionListTest.java b/android/guava-tests/test/com/google/common/util/concurrent/ExecutionListTest.java
index 5bd3cf7f44da..34678ed256b8 100644
--- a/android/guava-tests/test/com/google/common/util/concurrent/ExecutionListTest.java
+++ b/android/guava-tests/test/com/google/common/util/concurrent/ExecutionListTest.java
@@ -36,7 +36,6 @@ public class ExecutionListTest extends TestCase {
 
   private final ExecutionList list = new ExecutionList();
 
-
   public void testRunOnPopulatedList() throws Exception {
     Executor exec = Executors.newCachedThreadPool();
     CountDownLatch countDownLatch = new CountDownLatch(3);
@@ -67,7 +66,6 @@ public void run() {
     assertEquals(1, runCalled.get());
   }
 
-
   public void testExecute_idempotentConcurrently() throws InterruptedException {
     final CountDownLatch okayToRun = new CountDownLatch(1);
     final AtomicInteger runCalled = new AtomicInteger();
@@ -103,7 +101,6 @@ public void run() {
     assertEquals(1, runCalled.get());
   }
 
-
   public void testAddAfterRun() throws Exception {
     // Run the previous test
     testRunOnPopulatedList();
diff --git a/android/guava-tests/test/com/google/common/util/concurrent/ExecutionSequencerTest.java b/android/guava-tests/test/com/google/common/util/concurrent/ExecutionSequencerTest.java
index 1c03f5ac4e57..068287c1986b 100644
--- a/android/guava-tests/test/com/google/common/util/concurrent/ExecutionSequencerTest.java
+++ b/android/guava-tests/test/com/google/common/util/concurrent/ExecutionSequencerTest.java
@@ -88,7 +88,6 @@ public void testCancellationDoesNotViolateSerialization() {
     assertThat(thirdCallable.called).isTrue();
   }
 
-
   public void testCancellationMultipleThreads() throws Exception {
     final BlockingCallable blockingCallable = new BlockingCallable();
     ListenableFuture<Void> unused = serializer.submit(blockingCallable, executor);
@@ -116,7 +115,6 @@ public Boolean call() {
     assertThat(getDone(future2)).isFalse();
   }
 
-
   public void testSecondTaskWaitsForFirstEvenIfCancelled() throws Exception {
     final BlockingCallable blockingCallable = new BlockingCallable();
     ListenableFuture<Void> future1 = serializer.submit(blockingCallable, executor);
@@ -327,7 +325,6 @@ private static final class LongHolder {
   private static final int DIRECT_EXECUTIONS_PER_THREAD = 100;
 
   @GwtIncompatible // threads
-
   public void testAvoidsStackOverflow_multipleThreads() throws Exception {
     final LongHolder holder = new LongHolder();
     final ArrayList<ListenableFuture<Integer>> lengthChecks = new ArrayList<>();
diff --git a/android/guava-tests/test/com/google/common/util/concurrent/FluentFutureTest.java b/android/guava-tests/test/com/google/common/util/concurrent/FluentFutureTest.java
index cc4751d0f217..ab53f538307e 100644
--- a/android/guava-tests/test/com/google/common/util/concurrent/FluentFutureTest.java
+++ b/android/guava-tests/test/com/google/common/util/concurrent/FluentFutureTest.java
@@ -132,7 +132,6 @@ public ListenableFuture<Integer> apply(Integer input) {
     assertThat(f.get()).isEqualTo(2);
   }
 
-
   @GwtIncompatible // withTimeout
   public void testWithTimeout() throws Exception {
     ScheduledExecutorService executor = newScheduledThreadPool(1);
diff --git a/android/guava-tests/test/com/google/common/util/concurrent/ForwardingObjectTester.java b/android/guava-tests/test/com/google/common/util/concurrent/ForwardingObjectTester.java
index 021d96de7436..84b0426a6830 100644
--- a/android/guava-tests/test/com/google/common/util/concurrent/ForwardingObjectTester.java
+++ b/android/guava-tests/test/com/google/common/util/concurrent/ForwardingObjectTester.java
@@ -61,7 +61,7 @@ static <T extends ForwardingObject> void testForwardingObject(final Class<T> for
             new Function<Object, T>() {
               @Override
               public T apply(Object delegate) {
-                T mock = mock(forwarderClass, CALLS_REAL_METHODS.get());
+                T mock = mock(forwarderClass, CALLS_REAL_METHODS);
                 try {
                   T stubber = doReturn(delegate).when(mock);
                   DELEGATE_METHOD.invoke(stubber);
diff --git a/android/guava-tests/test/com/google/common/util/concurrent/FutureCallbackTest.java b/android/guava-tests/test/com/google/common/util/concurrent/FutureCallbackTest.java
index 4febc5a8dcc5..5a1464d05ce7 100644
--- a/android/guava-tests/test/com/google/common/util/concurrent/FutureCallbackTest.java
+++ b/android/guava-tests/test/com/google/common/util/concurrent/FutureCallbackTest.java
@@ -24,8 +24,8 @@
 import com.google.common.annotations.GwtIncompatible;
 import java.util.concurrent.CancellationException;
 import java.util.concurrent.Executor;
+import javax.annotation.CheckForNull;
 import junit.framework.TestCase;
-import org.checkerframework.checker.nullness.compatqual.NullableDecl;
 import org.mockito.Mockito;
 
 /**
@@ -157,8 +157,8 @@ public void execute(Runnable command) {
   }
 
   private final class MockCallback implements FutureCallback<String> {
-    @NullableDecl private String value = null;
-    @NullableDecl private Throwable failure = null;
+    @CheckForNull private String value = null;
+    @CheckForNull private Throwable failure = null;
     private boolean wasCalled = false;
 
     MockCallback(String expectedValue) {
diff --git a/android/guava-tests/test/com/google/common/util/concurrent/FuturesGetCheckedTest.java b/android/guava-tests/test/com/google/common/util/concurrent/FuturesGetCheckedTest.java
index 72b5a46564b6..666a1892982f 100644
--- a/android/guava-tests/test/com/google/common/util/concurrent/FuturesGetCheckedTest.java
+++ b/android/guava-tests/test/com/google/common/util/concurrent/FuturesGetCheckedTest.java
@@ -353,7 +353,7 @@ public void testGetCheckedUntimed_exceptionClassUsedInitCause() {
 
   public static final class WillBeUnloadedException extends Exception {}
 
-
+  @AndroidIncompatible // "Parent ClassLoader may not be null"; maybe avoidable if we try?
   public void testGetChecked_classUnloading() throws Exception {
     WeakReference<?> classUsedByGetChecked = doTestClassUnloading();
     GcFinalization.awaitClear(classUsedByGetChecked);
@@ -381,5 +381,8 @@ private WeakReference<?> doTestClassUnloading() throws Exception {
    * environment that forces Futures.getChecked to its fallback WeakSetValidator. One awful way of
    * doing so would be to derive a separate test library by using remove_from_jar to strip out
    * ClassValueValidator.
+   *
+   * Fortunately, we get pretty good coverage "by accident": We run all these tests against the
+   * *backport*, where ClassValueValidator is not present.
    */
 }
diff --git a/android/guava-tests/test/com/google/common/util/concurrent/FuturesTest.java b/android/guava-tests/test/com/google/common/util/concurrent/FuturesTest.java
index fa3b14a26830..6fa2a32df1c7 100644
--- a/android/guava-tests/test/com/google/common/util/concurrent/FuturesTest.java
+++ b/android/guava-tests/test/com/google/common/util/concurrent/FuturesTest.java
@@ -53,6 +53,7 @@
 import static java.util.concurrent.Executors.newSingleThreadExecutor;
 import static java.util.concurrent.Executors.newSingleThreadScheduledExecutor;
 import static java.util.concurrent.TimeUnit.MILLISECONDS;
+import static java.util.concurrent.TimeUnit.NANOSECONDS;
 import static java.util.concurrent.TimeUnit.SECONDS;
 
 import com.google.common.annotations.GwtCompatible;
@@ -87,9 +88,9 @@
 import java.util.concurrent.atomic.AtomicBoolean;
 import java.util.logging.LogRecord;
 import java.util.logging.Logger;
+import javax.annotation.CheckForNull;
 import junit.framework.AssertionFailedError;
 import junit.framework.TestCase;
-import org.checkerframework.checker.nullness.compatqual.NullableDecl;
 
 /**
  * Unit tests for {@link Futures}.
@@ -410,7 +411,6 @@ public ListenableFuture<Bar> apply(Foo unused) {
   }
 
   @GwtIncompatible // threads
-
   public void testTransformAsync_interruptPropagatesToTransformingThread() throws Exception {
     SettableFuture<String> input = SettableFuture.create();
     final CountDownLatch inFunction = new CountDownLatch(1);
@@ -803,7 +803,6 @@ public void testTransform_Executor() throws Exception {
   }
 
   @GwtIncompatible // Threads
-
   public void testTransformAsync_functionToString() throws Exception {
     final CountDownLatch functionCalled = new CountDownLatch(1);
     final CountDownLatch functionBlocking = new CountDownLatch(1);
@@ -1132,7 +1131,6 @@ public ListenableFuture<Integer> apply(Throwable t) {
   }
 
   @GwtIncompatible // threads
-
   public void testCatchingAsync_interruptPropagatesToTransformingThread() throws Exception {
     SettableFuture<String> input = SettableFuture.create();
     final CountDownLatch inFunction = new CountDownLatch(1);
@@ -1172,7 +1170,6 @@ public ListenableFuture<String> apply(Throwable t) throws Exception {
   }
 
   @GwtIncompatible // Threads
-
   public void testCatchingAsync_functionToString() throws Exception {
     final CountDownLatch functionCalled = new CountDownLatch(1);
     final CountDownLatch functionBlocking = new CountDownLatch(1);
@@ -1749,7 +1746,6 @@ public void testTransformAsync_asyncFunction_nullInsteadOfFuture() throws Except
   }
 
   @GwtIncompatible // threads
-
   public void testTransformAsync_asyncFunction_cancelledWhileApplyingFunction()
       throws InterruptedException, ExecutionException {
     final CountDownLatch inFunction = new CountDownLatch(1);
@@ -1784,7 +1780,6 @@ public ListenableFuture<Integer> apply(String input) throws Exception {
   }
 
   @GwtIncompatible // threads
-
   public void testTransformAsync_asyncFunction_cancelledBeforeApplyingFunction()
       throws InterruptedException {
     final AtomicBoolean functionCalled = new AtomicBoolean();
@@ -1858,7 +1853,6 @@ public void testSubmitAsync_asyncCallable_nullInsteadOfFuture() throws Exception
   }
 
   @GwtIncompatible // threads
-
   public void testSubmitAsync_asyncCallable_cancelledWhileApplyingFunction()
       throws InterruptedException, ExecutionException {
     final CountDownLatch inFunction = new CountDownLatch(1);
@@ -1892,7 +1886,6 @@ public ListenableFuture<Integer> call() throws InterruptedException {
   }
 
   @GwtIncompatible // threads
-
   public void testSubmitAsync_asyncCallable_cancelledBeforeApplyingFunction()
       throws InterruptedException {
     final AtomicBoolean callableCalled = new AtomicBoolean();
@@ -1926,7 +1919,6 @@ public void run() {
   }
 
   @GwtIncompatible // threads
-
   public void testSubmitAsync_asyncCallable_returnsInterruptedFuture() throws InterruptedException {
     assertThat(Thread.interrupted()).isFalse();
     SettableFuture<Integer> cancelledFuture = SettableFuture.create();
@@ -2015,7 +2007,6 @@ public void run() {
   }
 
   @GwtIncompatible // threads
-
   public void testScheduleAsync_asyncCallable_error() throws InterruptedException {
     final Error error = new Error("deliberate");
     AsyncCallable<Integer> callable =
@@ -2037,14 +2028,10 @@ public ListenableFuture<Integer> call() {
   }
 
   @GwtIncompatible // threads
-
   public void testScheduleAsync_asyncCallable_nullInsteadOfFuture() throws Exception {
     ListenableFuture<?> chainedFuture =
         scheduleAsync(
-            constantAsyncCallable(null),
-            1,
-            TimeUnit.NANOSECONDS,
-            newSingleThreadScheduledExecutor());
+            constantAsyncCallable(null), 1, NANOSECONDS, newSingleThreadScheduledExecutor());
     try {
       chainedFuture.get();
       fail();
@@ -2059,7 +2046,6 @@ public void testScheduleAsync_asyncCallable_nullInsteadOfFuture() throws Excepti
   }
 
   @GwtIncompatible // threads
-
   public void testScheduleAsync_asyncCallable_cancelledWhileApplyingFunction()
       throws InterruptedException, ExecutionException {
     final CountDownLatch inFunction = new CountDownLatch(1);
@@ -2075,7 +2061,7 @@ public ListenableFuture<Integer> call() throws InterruptedException {
           }
         };
     ListenableFuture<Integer> future =
-        scheduleAsync(callable, 1, TimeUnit.NANOSECONDS, newSingleThreadScheduledExecutor());
+        scheduleAsync(callable, 1, NANOSECONDS, newSingleThreadScheduledExecutor());
     inFunction.await();
     future.cancel(false);
     callableDone.countDown();
@@ -2092,7 +2078,6 @@ public ListenableFuture<Integer> call() throws InterruptedException {
   }
 
   @GwtIncompatible // threads
-
   public void testScheduleAsync_asyncCallable_cancelledBeforeCallingFunction()
       throws InterruptedException {
     final AtomicBoolean callableCalled = new AtomicBoolean();
@@ -2114,7 +2099,7 @@ public void run() {
             awaitUninterruptibly(beforeFunction);
           }
         });
-    ListenableFuture<Integer> future = scheduleAsync(callable, 1, TimeUnit.NANOSECONDS, executor);
+    ListenableFuture<Integer> future = scheduleAsync(callable, 1, NANOSECONDS, executor);
     future.cancel(false);
 
     // Unpause the executor.
@@ -2547,7 +2532,6 @@ private static String createCombinedResult(Integer i, Boolean b) {
   }
 
   @GwtIncompatible // threads
-
   public void testWhenAllComplete_noLeakInterruption() throws Exception {
     final SettableFuture<String> stringFuture = SettableFuture.create();
     AsyncCallable<String> combiner =
@@ -2591,7 +2575,6 @@ public String call() throws Exception {
   }
 
   @GwtIncompatible // threads
-
   public void testWhenAllComplete_asyncResult() throws Exception {
     SettableFuture<Integer> futureInteger = SettableFuture.create();
     SettableFuture<Boolean> futureBoolean = SettableFuture.create();
@@ -2683,7 +2666,6 @@ public ListenableFuture<String> call() throws Exception {
   }
 
   @GwtIncompatible // threads
-
   public void testWhenAllComplete_cancelledNotInterrupted() throws Exception {
     SettableFuture<String> stringFuture = SettableFuture.create();
     SettableFuture<Boolean> booleanFuture = SettableFuture.create();
@@ -2722,7 +2704,6 @@ public ListenableFuture<String> call() throws Exception {
   }
 
   @GwtIncompatible // threads
-
   public void testWhenAllComplete_interrupted() throws Exception {
     SettableFuture<String> stringFuture = SettableFuture.create();
     SettableFuture<Boolean> booleanFuture = SettableFuture.create();
@@ -2815,7 +2796,6 @@ public void run() {
   }
 
   @GwtIncompatible // threads
-
   public void testWhenAllCompleteRunnable_resultCanceledWithoutInterrupt_doesNotInterruptRunnable()
       throws Exception {
     SettableFuture<String> stringFuture = SettableFuture.create();
@@ -2856,7 +2836,6 @@ public void run() {
   }
 
   @GwtIncompatible // threads
-
   public void testWhenAllCompleteRunnable_resultCanceledWithInterrupt_InterruptsRunnable()
       throws Exception {
     SettableFuture<String> stringFuture = SettableFuture.create();
@@ -3375,13 +3354,11 @@ private static List<String> conditionalPseudoTimedGetUninterruptibly(
         : pseudoTimedGetUninterruptibly(future, 2500, MILLISECONDS);
   }
 
-
   @GwtIncompatible // threads
   public void testAllAsList_extensive() throws InterruptedException {
     runExtensiveMergerTest(Merger.allMerger);
   }
 
-
   @GwtIncompatible // threads
   public void testSuccessfulAsList_extensive() throws InterruptedException {
     runExtensiveMergerTest(Merger.successMerger);
@@ -3700,7 +3677,7 @@ public void testNonCancellationPropagating_doesNotPropagate() throws Exception {
   @GwtIncompatible // used only in GwtIncompatible tests
   private static class TestException extends Exception {
 
-    TestException(@NullableDecl Throwable cause) {
+    TestException(@CheckForNull Throwable cause) {
       super(cause);
     }
   }
diff --git a/android/guava-tests/test/com/google/common/util/concurrent/FuturesTransformAsyncTest.java b/android/guava-tests/test/com/google/common/util/concurrent/FuturesTransformAsyncTest.java
index d0fcee2384be..24990200df04 100644
--- a/android/guava-tests/test/com/google/common/util/concurrent/FuturesTransformAsyncTest.java
+++ b/android/guava-tests/test/com/google/common/util/concurrent/FuturesTransformAsyncTest.java
@@ -131,7 +131,6 @@ public void testFutureCancellableBeforeOutputCompletion() throws Exception {
     }
   }
 
-
   public void testFutureCancellableBeforeFunctionCompletion() throws Exception {
     // Set the result in a separate thread since this test runs the function
     // (which will block) in the same thread.
diff --git a/android/guava-tests/test/com/google/common/util/concurrent/GeneratedMonitorTest.java b/android/guava-tests/test/com/google/common/util/concurrent/GeneratedMonitorTest.java
index 872197be8b91..adeb2d1aa7c3 100644
--- a/android/guava-tests/test/com/google/common/util/concurrent/GeneratedMonitorTest.java
+++ b/android/guava-tests/test/com/google/common/util/concurrent/GeneratedMonitorTest.java
@@ -43,7 +43,6 @@
  *
  * @author Justin T. Sampson
  */
-
 public class GeneratedMonitorTest extends TestCase {
 
   public static TestSuite suite() {
diff --git a/android/guava-tests/test/com/google/common/util/concurrent/InterruptibleMonitorTest.java b/android/guava-tests/test/com/google/common/util/concurrent/InterruptibleMonitorTest.java
index 4d7a45f9c46e..bb3b43b9d16b 100644
--- a/android/guava-tests/test/com/google/common/util/concurrent/InterruptibleMonitorTest.java
+++ b/android/guava-tests/test/com/google/common/util/concurrent/InterruptibleMonitorTest.java
@@ -22,7 +22,6 @@
  *
  * @author Justin T. Sampson
  */
-
 public class InterruptibleMonitorTest extends MonitorTestCase {
 
   public InterruptibleMonitorTest() {
diff --git a/android/guava-tests/test/com/google/common/util/concurrent/InterruptibleTaskTest.java b/android/guava-tests/test/com/google/common/util/concurrent/InterruptibleTaskTest.java
index a8e098955c36..fcfe744e05ac 100644
--- a/android/guava-tests/test/com/google/common/util/concurrent/InterruptibleTaskTest.java
+++ b/android/guava-tests/test/com/google/common/util/concurrent/InterruptibleTaskTest.java
@@ -17,13 +17,14 @@
 
 import static com.google.common.truth.Truth.assertThat;
 
+import java.lang.reflect.Method;
 import java.nio.channels.spi.AbstractInterruptibleChannel;
 import java.util.concurrent.CountDownLatch;
 import java.util.concurrent.TimeUnit;
+import java.util.concurrent.locks.AbstractOwnableSynchronizer;
 import java.util.concurrent.locks.LockSupport;
 import junit.framework.TestCase;
 
-
 public final class InterruptibleTaskTest extends TestCase {
 
   // Regression test for a deadlock where a task could be stuck busy waiting for the task to
@@ -52,7 +53,10 @@ String toPendingString() {
           }
 
           @Override
-          void afterRanInterruptibly(Void result, Throwable error) {}
+          void afterRanInterruptiblySuccess(Void result) {}
+
+          @Override
+          void afterRanInterruptiblyFailure(Throwable error) {}
         };
     Thread runner = new Thread(task);
     runner.start();
@@ -86,6 +90,14 @@ void doBegin() {
    * protect ourselves from that we want to make sure that tasks don't spin too much waiting for the
    * interrupting thread to complete the protocol.
    */
+  /*
+   * This test hangs (or maybe is just *very* slow) under Android.
+   *
+   * TODO(b/218700094): Ideally, get this to pass under Android. Failing that, convince ourselves
+   * that the test isn't exposing a real problem with InterruptibleTask, one that could matter in
+   * prod.
+   */
+  @AndroidIncompatible
   public void testInterruptIsSlow() throws Exception {
     final CountDownLatch isInterruptibleRegistered = new CountDownLatch(1);
     final SlowChannel slowChannel = new SlowChannel();
@@ -115,25 +127,38 @@ String toPendingString() {
           }
 
           @Override
-          void afterRanInterruptibly(Void result, Throwable error) {}
+          void afterRanInterruptiblySuccess(Void result) {}
+
+          @Override
+          void afterRanInterruptiblyFailure(Throwable error) {}
         };
     Thread runner = new Thread(task, "runner");
     runner.start();
     isInterruptibleRegistered.await();
     // trigger the interrupt on another thread since it will block
-    new Thread("Interrupter") {
-      @Override
-      public void run() {
-        task.interruptTask();
-      }
-    }.start();
+    Thread interrupter =
+        new Thread("Interrupter") {
+          @Override
+          public void run() {
+            task.interruptTask();
+          }
+        };
+    interrupter.start();
     // this will happen once the interrupt has been set which means that
     // 1. the runner has been woken up
     // 2. the interrupter is stuck in the call the Thread.interrupt()
 
     // after some period of time the runner thread should become blocked on the task because it is
     // waiting for the slow interrupting thread to complete Thread.interrupt
-    awaitBlockedOn(runner, task);
+    awaitBlockedOnInstanceOf(runner, InterruptibleTask.Blocker.class);
+
+    Object blocker = LockSupport.getBlocker(runner);
+    assertThat(blocker).isInstanceOf(AbstractOwnableSynchronizer.class);
+    Method getExclusiveOwnerThread =
+        AbstractOwnableSynchronizer.class.getDeclaredMethod("getExclusiveOwnerThread");
+    getExclusiveOwnerThread.setAccessible(true);
+    Thread owner = (Thread) getExclusiveOwnerThread.invoke(blocker);
+    assertThat(owner).isSameInstanceAs(interrupter);
 
     slowChannel.exitClose.countDown(); // release the interrupter
 
@@ -143,8 +168,9 @@ public void run() {
   }
 
   // waits for the given thread to be blocked on the given object
-  private static void awaitBlockedOn(Thread t, Object blocker) throws InterruptedException {
-    while (!isThreadBlockedOn(t, blocker)) {
+  private static void awaitBlockedOnInstanceOf(Thread t, Class<?> blocker)
+      throws InterruptedException {
+    while (!isThreadBlockedOnInstanceOf(t, blocker)) {
       if (t.getState() == Thread.State.TERMINATED) {
         throw new RuntimeException("Thread " + t + " exited unexpectedly");
       }
@@ -152,8 +178,8 @@ private static void awaitBlockedOn(Thread t, Object blocker) throws InterruptedE
     }
   }
 
-  private static boolean isThreadBlockedOn(Thread t, Object blocker) {
-    return t.getState() == Thread.State.WAITING && LockSupport.getBlocker(t) == blocker;
+  private static boolean isThreadBlockedOnInstanceOf(Thread t, Class<?> blocker) {
+    return t.getState() == Thread.State.WAITING && blocker.isInstance(LockSupport.getBlocker(t));
   }
 
   static final class SlowChannel extends AbstractInterruptibleChannel {
diff --git a/android/guava-tests/test/com/google/common/util/concurrent/JSR166TestCase.java b/android/guava-tests/test/com/google/common/util/concurrent/JSR166TestCase.java
index 0822ae14a8df..2f8e1b7355ac 100644
--- a/android/guava-tests/test/com/google/common/util/concurrent/JSR166TestCase.java
+++ b/android/guava-tests/test/com/google/common/util/concurrent/JSR166TestCase.java
@@ -675,7 +675,7 @@ void waitForThreadToEnterWaitState(Thread thread) {
 
   /**
    * Returns the number of milliseconds since time given by startNanoTime, which must have been
-   * previously returned from a call to {@link System.nanoTime()}.
+   * previously returned from a call to {@link System#nanoTime()}.
    */
   long millisElapsedSince(long startNanoTime) {
     return NANOSECONDS.toMillis(System.nanoTime() - startNanoTime);
diff --git a/android/guava-tests/test/com/google/common/util/concurrent/JdkFutureAdaptersTest.java b/android/guava-tests/test/com/google/common/util/concurrent/JdkFutureAdaptersTest.java
index 3bb819a349fd..741ff45de8c0 100644
--- a/android/guava-tests/test/com/google/common/util/concurrent/JdkFutureAdaptersTest.java
+++ b/android/guava-tests/test/com/google/common/util/concurrent/JdkFutureAdaptersTest.java
@@ -100,7 +100,6 @@ public void testListenInPoolThreadIgnoresExecutorWhenDelegateIsDone() throws Exc
     assertTrue(listenableFuture.isDone());
   }
 
-
   public void testListenInPoolThreadUsesGivenExecutor() throws Exception {
     ExecutorService executorService =
         newCachedThreadPool(new ThreadFactoryBuilder().setDaemon(true).build());
@@ -125,7 +124,6 @@ public void testListenInPoolThreadUsesGivenExecutor() throws Exception {
     assertTrue(listenableFuture.isDone());
   }
 
-
   public void testListenInPoolThreadCustomExecutorInterrupted() throws Exception {
     final CountDownLatch submitSuccessful = new CountDownLatch(1);
     ExecutorService executorService =
@@ -235,7 +233,6 @@ public synchronized void run() {
     }
   }
 
-
   @SuppressWarnings("IsInstanceIncompatibleType") // intentional.
   public void testListenInPoolThreadRunsListenerAfterRuntimeException() throws Exception {
     RuntimeExceptionThrowingFuture<String> input = new RuntimeExceptionThrowingFuture<>();
diff --git a/android/guava-tests/test/com/google/common/util/concurrent/ListenableFutureTaskTest.java b/android/guava-tests/test/com/google/common/util/concurrent/ListenableFutureTaskTest.java
index 8969a7574d04..fd51a7329fd7 100644
--- a/android/guava-tests/test/com/google/common/util/concurrent/ListenableFutureTaskTest.java
+++ b/android/guava-tests/test/com/google/common/util/concurrent/ListenableFutureTaskTest.java
@@ -80,7 +80,6 @@ protected void tearDown() throws Exception {
     super.tearDown();
   }
 
-
   public void testListenerDoesNotRunUntilTaskCompletes() throws Exception {
 
     // Test default state of not started.
@@ -106,7 +105,6 @@ public void testListenerDoesNotRunUntilTaskCompletes() throws Exception {
     assertFalse(task.isCancelled());
   }
 
-
   public void testListenerCalledOnException() throws Exception {
     throwException = true;
 
@@ -142,7 +140,6 @@ public void testListenerCalledOnCancelFromNotRunning() throws Exception {
     assertEquals(1, runLatch.getCount());
   }
 
-
   public void testListenerCalledOnCancelFromRunning() throws Exception {
     exec.execute(task);
     runLatch.await();
diff --git a/android/guava-tests/test/com/google/common/util/concurrent/ListenableFutureTester.java b/android/guava-tests/test/com/google/common/util/concurrent/ListenableFutureTester.java
index 2dcccdb1894f..575ed06567dd 100644
--- a/android/guava-tests/test/com/google/common/util/concurrent/ListenableFutureTester.java
+++ b/android/guava-tests/test/com/google/common/util/concurrent/ListenableFutureTester.java
@@ -29,7 +29,7 @@
 import java.util.concurrent.ExecutorService;
 import java.util.concurrent.Executors;
 import java.util.concurrent.TimeUnit;
-import org.checkerframework.checker.nullness.compatqual.NullableDecl;
+import javax.annotation.CheckForNull;
 
 /**
  * Used to test listenable future implementations.
@@ -67,7 +67,7 @@ public void tearDown() {
     exec.shutdown();
   }
 
-  public void testCompletedFuture(@NullableDecl Object expectedValue)
+  public void testCompletedFuture(@CheckForNull Object expectedValue)
       throws InterruptedException, ExecutionException {
     assertTrue(future.isDone());
     assertFalse(future.isCancelled());
@@ -94,7 +94,7 @@ public void testCancelledFuture() throws InterruptedException, ExecutionExceptio
     }
   }
 
-  public void testFailedFuture(@NullableDecl String message) throws InterruptedException {
+  public void testFailedFuture(@CheckForNull String message) throws InterruptedException {
     assertTrue(future.isDone());
     assertFalse(future.isCancelled());
 
diff --git a/android/guava-tests/test/com/google/common/util/concurrent/ListenerCallQueueTest.java b/android/guava-tests/test/com/google/common/util/concurrent/ListenerCallQueueTest.java
index 5fd9b950855b..e0eb32e6a54f 100644
--- a/android/guava-tests/test/com/google/common/util/concurrent/ListenerCallQueueTest.java
+++ b/android/guava-tests/test/com/google/common/util/concurrent/ListenerCallQueueTest.java
@@ -129,7 +129,6 @@ public void testEnqueueAndDispatch_withLabeledExceptions() {
         logHandler.getStoredLogRecords().get(0).getMessage());
   }
 
-
   public void testEnqueueAndDispatch_multithreaded() throws InterruptedException {
     Object listener = new Object();
     ExecutorService service = Executors.newFixedThreadPool(4);
@@ -153,7 +152,6 @@ public void testEnqueueAndDispatch_multithreaded() throws InterruptedException {
     }
   }
 
-
   public void testEnqueueAndDispatch_multithreaded_withThrowingRunnable()
       throws InterruptedException {
     Object listener = new Object();
diff --git a/android/guava-tests/test/com/google/common/util/concurrent/MonitorTestCase.java b/android/guava-tests/test/com/google/common/util/concurrent/MonitorTestCase.java
index 6d620ffc24cd..e355d35d7f81 100644
--- a/android/guava-tests/test/com/google/common/util/concurrent/MonitorTestCase.java
+++ b/android/guava-tests/test/com/google/common/util/concurrent/MonitorTestCase.java
@@ -26,7 +26,6 @@
  *
  * @author Justin T. Sampson
  */
-
 public abstract class MonitorTestCase extends TestCase {
 
   public class TestGuard extends Monitor.Guard {
diff --git a/android/guava-tests/test/com/google/common/util/concurrent/MoreExecutorsTest.java b/android/guava-tests/test/com/google/common/util/concurrent/MoreExecutorsTest.java
index fe4e7f540038..aac61735e998 100644
--- a/android/guava-tests/test/com/google/common/util/concurrent/MoreExecutorsTest.java
+++ b/android/guava-tests/test/com/google/common/util/concurrent/MoreExecutorsTest.java
@@ -88,7 +88,6 @@ public class MoreExecutorsTest extends JSR166TestCase {
         public void run() {}
       };
 
-
   public void testDirectExecutorServiceServiceInThreadExecution() throws Exception {
     final ListeningExecutorService executor = newDirectExecutorService();
     final ThreadLocal<Integer> threadLocalCount =
@@ -168,7 +167,6 @@ public Integer call() {
     assertEquals(10, threadLocalCount.get().intValue());
   }
 
-
   public void testDirectExecutorServiceServiceTermination() throws Exception {
     final ExecutorService executor = newDirectExecutorService();
     final CyclicBarrier barrier = new CyclicBarrier(2);
@@ -259,7 +257,6 @@ public Void call() throws Exception {
    * Test for a bug where threads weren't getting signaled when shutdown was called, only when tasks
    * completed.
    */
-
   public void testDirectExecutorService_awaitTermination_missedSignal() {
     final ExecutorService service = MoreExecutors.newDirectExecutorService();
     Thread waiter =
@@ -342,6 +339,7 @@ public void testListeningDecorator() throws Exception {
      */
   }
 
+  @AndroidIncompatible // Mocking ExecutorService is forbidden there. TODO(b/218700094): Don't mock.
   public void testListeningDecorator_noWrapExecuteTask() {
     ExecutorService delegate = mock(ExecutorService.class);
     ListeningExecutorService service = listeningDecorator(delegate);
@@ -354,7 +352,6 @@ public void run() {}
     verify(delegate).execute(task);
   }
 
-
   public void testListeningDecorator_scheduleSuccess() throws Exception {
     final CountDownLatch completed = new CountDownLatch(1);
     ScheduledThreadPoolExecutor delegate =
@@ -380,7 +377,6 @@ protected void afterExecute(Runnable r, Throwable t) {
     assertEquals(0, delegate.getQueue().size());
   }
 
-
   public void testListeningDecorator_scheduleFailure() throws Exception {
     ScheduledThreadPoolExecutor delegate = new ScheduledThreadPoolExecutor(1);
     ListeningScheduledExecutorService service = listeningDecorator(delegate);
@@ -391,7 +387,6 @@ public void testListeningDecorator_scheduleFailure() throws Exception {
     assertEquals(0, delegate.getQueue().size());
   }
 
-
   public void testListeningDecorator_schedulePeriodic() throws Exception {
     ScheduledThreadPoolExecutor delegate = new ScheduledThreadPoolExecutor(1);
     ListeningScheduledExecutorService service = listeningDecorator(delegate);
@@ -412,7 +407,6 @@ public void testListeningDecorator_schedulePeriodic() throws Exception {
     assertEquals(0, delegate.getQueue().size());
   }
 
-
   public void testListeningDecorator_cancelled() throws Exception {
     ScheduledThreadPoolExecutor delegate = new ScheduledThreadPoolExecutor(1);
     BlockingQueue<?> delegateQueue = delegate.getQueue();
@@ -566,7 +560,7 @@ public void run() {
     }
   }
 
-
+  @AndroidIncompatible // Mocking ExecutorService is forbidden there. TODO(b/218700094): Don't mock.
   public void testAddDelayedShutdownHook_success() throws InterruptedException {
     TestApplication application = new TestApplication();
     ExecutorService service = mock(ExecutorService.class);
@@ -578,7 +572,7 @@ public void testAddDelayedShutdownHook_success() throws InterruptedException {
     shutdownFirst.verify(service).awaitTermination(2, TimeUnit.SECONDS);
   }
 
-
+  @AndroidIncompatible // Mocking ExecutorService is forbidden there. TODO(b/218700094): Don't mock.
   public void testAddDelayedShutdownHook_interrupted() throws InterruptedException {
     TestApplication application = new TestApplication();
     ExecutorService service = mock(ExecutorService.class);
@@ -588,7 +582,6 @@ public void testAddDelayedShutdownHook_interrupted() throws InterruptedException
     verify(service).shutdown();
   }
 
-
   public void testGetExitingExecutorService_executorSetToUseDaemonThreads() {
     TestApplication application = new TestApplication();
     ThreadPoolExecutor executor =
@@ -597,7 +590,7 @@ public void testGetExitingExecutorService_executorSetToUseDaemonThreads() {
     assertTrue(executor.getThreadFactory().newThread(EMPTY_RUNNABLE).isDaemon());
   }
 
-
+  @AndroidIncompatible // Mocking ExecutorService is forbidden there. TODO(b/218700094): Don't mock.
   public void testGetExitingExecutorService_executorDelegatesToOriginal() {
     TestApplication application = new TestApplication();
     ThreadPoolExecutor executor = mock(ThreadPoolExecutor.class);
@@ -607,7 +600,7 @@ public void testGetExitingExecutorService_executorDelegatesToOriginal() {
     verify(executor).execute(EMPTY_RUNNABLE);
   }
 
-
+  @AndroidIncompatible // Mocking ExecutorService is forbidden there. TODO(b/218700094): Don't mock.
   public void testGetExitingExecutorService_shutdownHookRegistered() throws InterruptedException {
     TestApplication application = new TestApplication();
     ThreadPoolExecutor executor = mock(ThreadPoolExecutor.class);
@@ -618,7 +611,6 @@ public void testGetExitingExecutorService_shutdownHookRegistered() throws Interr
     verify(executor).shutdown();
   }
 
-
   public void testGetExitingScheduledExecutorService_executorSetToUseDaemonThreads() {
     TestApplication application = new TestApplication();
     ScheduledThreadPoolExecutor executor = new ScheduledThreadPoolExecutor(1);
@@ -626,7 +618,7 @@ public void testGetExitingScheduledExecutorService_executorSetToUseDaemonThreads
     assertTrue(executor.getThreadFactory().newThread(EMPTY_RUNNABLE).isDaemon());
   }
 
-
+  @AndroidIncompatible // Mocking ExecutorService is forbidden there. TODO(b/218700094): Don't mock.
   public void testGetExitingScheduledExecutorService_executorDelegatesToOriginal() {
     TestApplication application = new TestApplication();
     ScheduledThreadPoolExecutor executor = mock(ScheduledThreadPoolExecutor.class);
@@ -636,7 +628,7 @@ public void testGetExitingScheduledExecutorService_executorDelegatesToOriginal()
     verify(executor).execute(EMPTY_RUNNABLE);
   }
 
-
+  @AndroidIncompatible // Mocking ExecutorService is forbidden there. TODO(b/218700094): Don't mock.
   public void testGetScheduledExitingExecutorService_shutdownHookRegistered()
       throws InterruptedException {
     TestApplication application = new TestApplication();
@@ -669,7 +661,6 @@ public void run() {
     assertEquals(oldName, Thread.currentThread().getName());
   }
 
-
   public void testExecutors_nullCheck() throws Exception {
     new ClassSanityTester()
         .setDefault(RateLimiter.class, RateLimiter.create(1.0))
@@ -699,14 +690,13 @@ synchronized void shutdown() throws InterruptedException {
   /* Half of a 1-second timeout in nanoseconds */
   private static final long HALF_SECOND_NANOS = NANOSECONDS.convert(1L, SECONDS) / 2;
 
-
   public void testShutdownAndAwaitTermination_immediateShutdown() throws Exception {
     ExecutorService service = Executors.newSingleThreadExecutor();
     assertTrue(shutdownAndAwaitTermination(service, 1L, SECONDS));
     assertTrue(service.isTerminated());
   }
 
-
+  @AndroidIncompatible // Mocking ExecutorService is forbidden there. TODO(b/218700094): Don't mock.
   public void testShutdownAndAwaitTermination_immediateShutdownInternal() throws Exception {
     ExecutorService service = mock(ExecutorService.class);
     when(service.awaitTermination(HALF_SECOND_NANOS, NANOSECONDS)).thenReturn(true);
@@ -716,7 +706,7 @@ public void testShutdownAndAwaitTermination_immediateShutdownInternal() throws E
     verify(service).awaitTermination(HALF_SECOND_NANOS, NANOSECONDS);
   }
 
-
+  @AndroidIncompatible // Mocking ExecutorService is forbidden there. TODO(b/218700094): Don't mock.
   public void testShutdownAndAwaitTermination_forcedShutDownInternal() throws Exception {
     ExecutorService service = mock(ExecutorService.class);
     when(service.awaitTermination(HALF_SECOND_NANOS, NANOSECONDS))
@@ -729,7 +719,7 @@ public void testShutdownAndAwaitTermination_forcedShutDownInternal() throws Exce
     verify(service).shutdownNow();
   }
 
-
+  @AndroidIncompatible // Mocking ExecutorService is forbidden there. TODO(b/218700094): Don't mock.
   public void testShutdownAndAwaitTermination_nonTerminationInternal() throws Exception {
     ExecutorService service = mock(ExecutorService.class);
     when(service.awaitTermination(HALF_SECOND_NANOS, NANOSECONDS))
@@ -741,7 +731,7 @@ public void testShutdownAndAwaitTermination_nonTerminationInternal() throws Exce
     verify(service).shutdownNow();
   }
 
-
+  @AndroidIncompatible // Mocking ExecutorService is forbidden there. TODO(b/218700094): Don't mock.
   public void testShutdownAndAwaitTermination_interruptedInternal() throws Exception {
     final ExecutorService service = mock(ExecutorService.class);
     when(service.awaitTermination(HALF_SECOND_NANOS, NANOSECONDS))
diff --git a/android/guava-tests/test/com/google/common/util/concurrent/SequentialExecutorTest.java b/android/guava-tests/test/com/google/common/util/concurrent/SequentialExecutorTest.java
index 20209e8b80dc..80e7ab2e1241 100644
--- a/android/guava-tests/test/com/google/common/util/concurrent/SequentialExecutorTest.java
+++ b/android/guava-tests/test/com/google/common/util/concurrent/SequentialExecutorTest.java
@@ -274,7 +274,14 @@ public void run() {
     assertEquals(1, numCalls.get());
   }
 
-
+  /*
+   * Under Android, MyError propagates up and fails the test?
+   *
+   * TODO(b/218700094): Does this matter to prod users, or is it just a feature of our testing
+   * environment? If the latter, maybe write a custom Executor that avoids failing the test when it
+   * sees an Error?
+   */
+  @AndroidIncompatible
   public void testTaskThrowsError() throws Exception {
     class MyError extends Error {}
     final CyclicBarrier barrier = new CyclicBarrier(2);
@@ -313,7 +320,6 @@ public void run() {
     }
   }
 
-
   public void testRejectedExecutionThrownWithMultipleCalls() throws Exception {
     final CountDownLatch latch = new CountDownLatch(1);
     final SettableFuture<?> future = SettableFuture.create();
diff --git a/android/guava-tests/test/com/google/common/util/concurrent/ServiceManagerTest.java b/android/guava-tests/test/com/google/common/util/concurrent/ServiceManagerTest.java
index 2092aff52887..7db6b06aef35 100644
--- a/android/guava-tests/test/com/google/common/util/concurrent/ServiceManagerTest.java
+++ b/android/guava-tests/test/com/google/common/util/concurrent/ServiceManagerTest.java
@@ -119,21 +119,17 @@ protected void doStop() {
     }
   }
 
-
   public void testServiceStartupTimes() {
     Service a = new NoOpDelayedService(150);
     Service b = new NoOpDelayedService(353);
     ServiceManager serviceManager = new ServiceManager(asList(a, b));
     serviceManager.startAsync().awaitHealthy();
     ImmutableMap<Service, Long> startupTimes = serviceManager.startupTimes();
-    assertEquals(2, startupTimes.size());
-    // TODO(kak): Use assertThat(startupTimes.get(a)).isAtLeast(150);
-    assertTrue(startupTimes.get(a) >= 150);
-    // TODO(kak): Use assertThat(startupTimes.get(b)).isAtLeast(353);
-    assertTrue(startupTimes.get(b) >= 353);
+    assertThat(startupTimes).hasSize(2);
+    assertThat(startupTimes.get(a)).isAtLeast(150);
+    assertThat(startupTimes.get(b)).isAtLeast(353);
   }
 
-
   public void testServiceStartupTimes_selfStartingServices() {
     // This tests to ensure that:
     // 1. service times are accurate when the service is started by the manager
@@ -159,9 +155,8 @@ protected void doStart() {
     ServiceManager serviceManager = new ServiceManager(asList(a, b));
     serviceManager.startAsync().awaitHealthy();
     ImmutableMap<Service, Long> startupTimes = serviceManager.startupTimes();
-    assertEquals(2, startupTimes.size());
-    // TODO(kak): Use assertThat(startupTimes.get(a)).isAtLeast(150);
-    assertTrue(startupTimes.get(a) >= 150);
+    assertThat(startupTimes).hasSize(2);
+    assertThat(startupTimes.get(a)).isAtLeast(150);
     // Service b startup takes at least 353 millis, but starting the timer is delayed by at least
     // 150 milliseconds. so in a perfect world the timing would be 353-150=203ms, but since either
     // of our sleep calls can be arbitrarily delayed we should just assert that there is a time
@@ -169,7 +164,6 @@ protected void doStart() {
     assertThat(startupTimes.get(b)).isNotNull();
   }
 
-
   public void testServiceStartStop() {
     Service a = new NoOpService();
     Service b = new NoOpService();
@@ -191,7 +185,6 @@ public void testServiceStartStop() {
     assertTrue(listener.failedServices.isEmpty());
   }
 
-
   public void testFailStart() throws Exception {
     Service a = new NoOpService();
     Service b = new FailStartService();
@@ -219,7 +212,6 @@ public void testFailStart() throws Exception {
     assertTrue(listener.stoppedCalled);
   }
 
-
   public void testFailRun() throws Exception {
     Service a = new NoOpService();
     Service b = new FailRunService();
@@ -242,7 +234,6 @@ public void testFailRun() throws Exception {
     assertTrue(listener.stoppedCalled);
   }
 
-
   public void testFailStop() throws Exception {
     Service a = new NoOpService();
     Service b = new FailStopService();
@@ -271,7 +262,6 @@ public void testToString() throws Exception {
     assertThat(toString).contains("FailStartService");
   }
 
-
   public void testTimeouts() throws Exception {
     Service a = new NoOpDelayedService(50);
     ServiceManager manager = new ServiceManager(asList(a));
@@ -448,7 +438,6 @@ public String format(LogRecord record) {
    * Tests that a ServiceManager can be fully shut down if one of its failure listeners is slow or
    * even permanently blocked.
    */
-
   public void testListenerDeadlock() throws InterruptedException {
     final CountDownLatch failEnter = new CountDownLatch(1);
     final CountDownLatch failLeave = new CountDownLatch(1);
@@ -609,7 +598,6 @@ public final Throwable failureCause() {
    *
    * <p>Before the bug was fixed this test would fail at least 30% of the time.
    */
-
   public void testTransitionRace() throws TimeoutException {
     for (int k = 0; k < 1000; k++) {
       List<Service> services = Lists.newArrayList();
diff --git a/android/guava-tests/test/com/google/common/util/concurrent/SettableFutureTest.java b/android/guava-tests/test/com/google/common/util/concurrent/SettableFutureTest.java
index 9b8b88f27167..105e8de0410e 100644
--- a/android/guava-tests/test/com/google/common/util/concurrent/SettableFutureTest.java
+++ b/android/guava-tests/test/com/google/common/util/concurrent/SettableFutureTest.java
@@ -51,19 +51,16 @@ public void testDefaultState() throws Exception {
     }
   }
 
-
   public void testSetValue() throws Exception {
     assertTrue(future.set("value"));
     tester.testCompletedFuture("value");
   }
 
-
   public void testSetFailure() throws Exception {
     assertTrue(future.setException(new Exception("failure")));
     tester.testFailedFuture("failure");
   }
 
-
   public void testSetFailureNull() throws Exception {
     try {
       future.setException(null);
@@ -75,7 +72,6 @@ public void testSetFailureNull() throws Exception {
     tester.testFailedFuture("failure");
   }
 
-
   public void testCancel() throws Exception {
     assertTrue(future.cancel(true));
     tester.testCancelledFuture();
diff --git a/android/guava-tests/test/com/google/common/util/concurrent/SimpleTimeLimiterTest.java b/android/guava-tests/test/com/google/common/util/concurrent/SimpleTimeLimiterTest.java
index 04b824f823f9..35406864dce4 100644
--- a/android/guava-tests/test/com/google/common/util/concurrent/SimpleTimeLimiterTest.java
+++ b/android/guava-tests/test/com/google/common/util/concurrent/SimpleTimeLimiterTest.java
@@ -34,7 +34,6 @@
  * @author kevinb
  * @author Jens Nyman
  */
-
 public class SimpleTimeLimiterTest extends TestCase {
 
   private static final long DELAY_MS = 50;
diff --git a/android/guava-tests/test/com/google/common/util/concurrent/StripedTest.java b/android/guava-tests/test/com/google/common/util/concurrent/StripedTest.java
index fa9d87f752f2..688d6fd34ac0 100644
--- a/android/guava-tests/test/com/google/common/util/concurrent/StripedTest.java
+++ b/android/guava-tests/test/com/google/common/util/concurrent/StripedTest.java
@@ -129,7 +129,7 @@ public void testSizes() {
     assertTrue(Striped.lazyWeakLock(256).size() == 256);
   }
 
-
+  @AndroidIncompatible // Presumably GC doesn't trigger, despite our efforts.
   public void testWeakImplementations() {
     for (Striped<?> striped : weakImplementations()) {
       WeakReference<Object> weakRef = new WeakReference<>(striped.get(new Object()));
@@ -137,7 +137,7 @@ public void testWeakImplementations() {
     }
   }
 
-
+  @AndroidIncompatible // Presumably GC doesn't trigger, despite our efforts.
   public void testWeakReadWrite() {
     Striped<ReadWriteLock> striped = Striped.lazyWeakReadWriteLock(1000);
     Object key = new Object();
@@ -150,7 +150,7 @@ public void testWeakReadWrite() {
     readLock.unlock();
   }
 
-
+  @AndroidIncompatible // Presumably GC doesn't trigger, despite our efforts.
   public void testStrongImplementations() {
     for (Striped<?> striped : strongImplementations()) {
       WeakReference<Object> weakRef = new WeakReference<>(striped.get(new Object()));
diff --git a/android/guava-tests/test/com/google/common/util/concurrent/SupplementalMonitorTest.java b/android/guava-tests/test/com/google/common/util/concurrent/SupplementalMonitorTest.java
index 8a52ffeed591..5b77f9a59ef5 100644
--- a/android/guava-tests/test/com/google/common/util/concurrent/SupplementalMonitorTest.java
+++ b/android/guava-tests/test/com/google/common/util/concurrent/SupplementalMonitorTest.java
@@ -33,7 +33,6 @@
  *
  * @author Justin T. Sampson
  */
-
 public class SupplementalMonitorTest extends TestCase {
 
   public void testLeaveWithoutEnterThrowsIMSE() {
diff --git a/android/guava-tests/test/com/google/common/util/concurrent/TestThread.java b/android/guava-tests/test/com/google/common/util/concurrent/TestThread.java
index 1c3c88818e4b..f85d3134dd25 100644
--- a/android/guava-tests/test/com/google/common/util/concurrent/TestThread.java
+++ b/android/guava-tests/test/com/google/common/util/concurrent/TestThread.java
@@ -28,8 +28,8 @@
 import java.util.concurrent.SynchronousQueue;
 import java.util.concurrent.TimeUnit;
 import java.util.concurrent.TimeoutException;
+import javax.annotation.CheckForNull;
 import junit.framework.AssertionFailedError;
-import org.checkerframework.checker.nullness.compatqual.NullableDecl;
 
 /**
  * A helper for concurrency testing. One or more {@code TestThread} instances are instantiated in a
@@ -168,7 +168,7 @@ public void callAndAssertWaits(String methodName, Object conditionLikeObject) th
    * Asserts that a prior call that had caused this thread to block or wait has since returned
    * normally.
    */
-  public void assertPriorCallReturns(@NullableDecl String methodName) throws Exception {
+  public void assertPriorCallReturns(@CheckForNull String methodName) throws Exception {
     assertEquals(null, getResponse(methodName).getResult());
   }
 
@@ -176,7 +176,7 @@ public void assertPriorCallReturns(@NullableDecl String methodName) throws Excep
    * Asserts that a prior call that had caused this thread to block or wait has since returned the
    * expected boolean value.
    */
-  public void assertPriorCallReturns(boolean expected, @NullableDecl String methodName)
+  public void assertPriorCallReturns(boolean expected, @CheckForNull String methodName)
       throws Exception {
     assertEquals(expected, getResponse(methodName).getResult());
   }
diff --git a/android/guava-tests/test/com/google/common/util/concurrent/ThreadFactoryBuilderTest.java b/android/guava-tests/test/com/google/common/util/concurrent/ThreadFactoryBuilderTest.java
index 7684b963376a..a3a7b8e79dcc 100644
--- a/android/guava-tests/test/com/google/common/util/concurrent/ThreadFactoryBuilderTest.java
+++ b/android/guava-tests/test/com/google/common/util/concurrent/ThreadFactoryBuilderTest.java
@@ -56,7 +56,6 @@ public void setUp() {
     builder = new ThreadFactoryBuilder();
   }
 
-
   public void testThreadFactoryBuilder_defaults() throws InterruptedException {
     ThreadFactory threadFactory = builder.build();
     Thread thread = threadFactory.newThread(monitoredRunnable);
@@ -93,7 +92,6 @@ private static void checkThreadPoolName(Thread thread, int threadId) {
     assertThat(thread.getName()).matches("^pool-\\d+-thread-" + threadId + "$");
   }
 
-
   public void testNameFormatWithPercentS_custom() {
     String format = "super-duper-thread-%s";
     ThreadFactory factory = builder.setNameFormat(format).build();
@@ -102,7 +100,6 @@ public void testNameFormatWithPercentS_custom() {
     }
   }
 
-
   public void testNameFormatWithPercentD_custom() {
     String format = "super-duper-thread-%d";
     ThreadFactory factory = builder.setNameFormat(format).build();
@@ -111,21 +108,18 @@ public void testNameFormatWithPercentD_custom() {
     }
   }
 
-
   public void testDaemon_false() {
     ThreadFactory factory = builder.setDaemon(false).build();
     Thread thread = factory.newThread(monitoredRunnable);
     assertFalse(thread.isDaemon());
   }
 
-
   public void testDaemon_true() {
     ThreadFactory factory = builder.setDaemon(true).build();
     Thread thread = factory.newThread(monitoredRunnable);
     assertTrue(thread.isDaemon());
   }
 
-
   public void testPriority_custom() {
     for (int i = Thread.MIN_PRIORITY; i <= Thread.MAX_PRIORITY; i++) {
       ThreadFactory factory = builder.setPriority(i).build();
@@ -150,7 +144,6 @@ public void testPriority_tooHigh() {
     }
   }
 
-
   public void testUncaughtExceptionHandler_custom() {
     assertEquals(
         UNCAUGHT_EXCEPTION_HANDLER,
@@ -161,7 +154,6 @@ public void testUncaughtExceptionHandler_custom() {
             .getUncaughtExceptionHandler());
   }
 
-
   public void testBuildMutateBuild() {
     ThreadFactory factory1 = builder.setPriority(1).build();
     assertEquals(1, factory1.newThread(monitoredRunnable).getPriority());
@@ -177,7 +169,6 @@ public void testBuildTwice() {
     unused = builder.build(); // this is *also* allowed
   }
 
-
   public void testBuildMutate() {
     ThreadFactory factory1 = builder.setPriority(1).build();
     assertEquals(1, factory1.newThread(monitoredRunnable).getPriority());
@@ -186,7 +177,6 @@ public void testBuildMutate() {
     assertEquals(1, factory1.newThread(monitoredRunnable).getPriority());
   }
 
-
   public void testThreadFactory() throws InterruptedException {
     final String THREAD_NAME = "ludicrous speed";
     final int THREAD_PRIORITY = 1;
diff --git a/android/guava-tests/test/com/google/common/util/concurrent/TrustedListenableFutureTaskTest.java b/android/guava-tests/test/com/google/common/util/concurrent/TrustedListenableFutureTaskTest.java
index 157afa79d8a6..e735ae02a43c 100644
--- a/android/guava-tests/test/com/google/common/util/concurrent/TrustedListenableFutureTaskTest.java
+++ b/android/guava-tests/test/com/google/common/util/concurrent/TrustedListenableFutureTaskTest.java
@@ -84,7 +84,6 @@ public Integer call() throws Exception {
   }
 
   @GwtIncompatible // blocking wait
-
   public void testCancel_interrupted() throws Exception {
     final AtomicBoolean interruptedExceptionThrown = new AtomicBoolean();
     final CountDownLatch enterLatch = new CountDownLatch(1);
@@ -135,7 +134,6 @@ public void run() {
   }
 
   @GwtIncompatible // blocking wait
-
   public void testRunIdempotency() throws Exception {
     final int numThreads = 10;
     final ExecutorService executor = Executors.newFixedThreadPool(numThreads);
@@ -171,7 +169,6 @@ public void run() {
   }
 
   @GwtIncompatible // blocking wait
-
   public void testToString() throws Exception {
     final CountDownLatch enterLatch = new CountDownLatch(1);
     final CountDownLatch exitLatch = new CountDownLatch(1);
diff --git a/android/guava-tests/test/com/google/common/util/concurrent/UncaughtExceptionHandlersTest.java b/android/guava-tests/test/com/google/common/util/concurrent/UncaughtExceptionHandlersTest.java
index eb8455b18323..4a26b4976578 100644
--- a/android/guava-tests/test/com/google/common/util/concurrent/UncaughtExceptionHandlersTest.java
+++ b/android/guava-tests/test/com/google/common/util/concurrent/UncaughtExceptionHandlersTest.java
@@ -23,7 +23,6 @@
 import junit.framework.TestCase;
 
 /** @author Gregory Kick */
-
 public class UncaughtExceptionHandlersTest extends TestCase {
 
   private Runtime runtimeMock;
diff --git a/android/guava-tests/test/com/google/common/util/concurrent/UninterruptibleFutureTest.java b/android/guava-tests/test/com/google/common/util/concurrent/UninterruptibleFutureTest.java
index 0d24266074b0..3f91b8123bd3 100644
--- a/android/guava-tests/test/com/google/common/util/concurrent/UninterruptibleFutureTest.java
+++ b/android/guava-tests/test/com/google/common/util/concurrent/UninterruptibleFutureTest.java
@@ -77,7 +77,6 @@ protected void tearDown() {
    * This first test doesn't test anything in Uninterruptibles, just demonstrates some normal
    * behavior of futures so that you can contrast the next test with it.
    */
-
   public void testRegularFutureInterrupted() throws ExecutionException {
 
     /*
@@ -116,7 +115,6 @@ public void testRegularFutureInterrupted() throws ExecutionException {
     assertTrue(sleeper.completed);
   }
 
-
   public void testMakeUninterruptible_timeoutPreservedThroughInterruption()
       throws ExecutionException {
 
@@ -155,32 +153,26 @@ public void run() {
     }
   }
 
-
   public void testMakeUninterruptible_untimed_uninterrupted() throws Exception {
     runUntimedInterruptsTest(0);
   }
 
-
   public void testMakeUninterruptible_untimed_interrupted() throws Exception {
     runUntimedInterruptsTest(1);
   }
 
-
   public void testMakeUninterruptible_untimed_multiplyInterrupted() throws Exception {
     runUntimedInterruptsTest(38);
   }
 
-
   public void testMakeUninterruptible_timed_uninterrupted() throws Exception {
     runTimedInterruptsTest(0);
   }
 
-
   public void testMakeUninterruptible_timed_interrupted() throws Exception {
     runTimedInterruptsTest(1);
   }
 
-
   public void testMakeUninterruptible_timed_multiplyInterrupted() throws Exception {
     runTimedInterruptsTest(38);
   }
@@ -218,7 +210,6 @@ private static void runNInterruptsTest(
   /**
    * Confirms that the test code triggers {@link InterruptedException} in a standard {@link Future}.
    */
-
   public void testMakeUninterruptible_plainFutureSanityCheck() throws Exception {
     SettableFuture<String> future = SettableFuture.create();
     FutureTask<Boolean> wasInterrupted = untimedInterruptReporter(future, true);
@@ -235,7 +226,6 @@ public void testMakeUninterruptible_plainFutureSanityCheck() throws Exception {
     }
   }
 
-
   public void testMakeUninterruptible_timedGetZeroTimeoutAttempted()
       throws TimeoutException, ExecutionException {
     SettableFuture<String> future = SettableFuture.create();
@@ -248,7 +238,6 @@ public void testMakeUninterruptible_timedGetZeroTimeoutAttempted()
     assertEquals(RESULT, getUninterruptibly(future, 0, SECONDS));
   }
 
-
   public void testMakeUninterruptible_timedGetNegativeTimeoutAttempted()
       throws TimeoutException, ExecutionException {
     SettableFuture<String> future = SettableFuture.create();
diff --git a/android/guava-tests/test/com/google/common/util/concurrent/UninterruptibleMonitorTest.java b/android/guava-tests/test/com/google/common/util/concurrent/UninterruptibleMonitorTest.java
index 59bf80878849..3e775bab5676 100644
--- a/android/guava-tests/test/com/google/common/util/concurrent/UninterruptibleMonitorTest.java
+++ b/android/guava-tests/test/com/google/common/util/concurrent/UninterruptibleMonitorTest.java
@@ -22,7 +22,6 @@
  *
  * @author Justin T. Sampson
  */
-
 public class UninterruptibleMonitorTest extends MonitorTestCase {
 
   public UninterruptibleMonitorTest() {
diff --git a/android/guava-tests/test/com/google/common/util/concurrent/UninterruptiblesTest.java b/android/guava-tests/test/com/google/common/util/concurrent/UninterruptiblesTest.java
index e58cf6a60ef1..ab8d5b0a8bc2 100644
--- a/android/guava-tests/test/com/google/common/util/concurrent/UninterruptiblesTest.java
+++ b/android/guava-tests/test/com/google/common/util/concurrent/UninterruptiblesTest.java
@@ -54,7 +54,6 @@
  *
  * @author Anthony Zana
  */
-
 public class UninterruptiblesTest extends TestCase {
   private static final String EXPECTED_TAKE = "expectedTake";
 
diff --git a/android/guava/pom.xml b/android/guava/pom.xml
index 5deda6e057fc..39611d4c9e3b 100644
--- a/android/guava/pom.xml
+++ b/android/guava/pom.xml
@@ -5,11 +5,12 @@
   <parent>
     <groupId>com.google.guava</groupId>
     <artifactId>guava-parent</artifactId>
-    <version>HEAD-android-SNAPSHOT</version>
+    <version>31.1-android</version>
   </parent>
   <artifactId>guava</artifactId>
   <packaging>bundle</packaging>
   <name>Guava: Google Core Libraries for Java</name>
+  <url>https://github.com/google/guava</url>
   <description>
     Guava is a suite of core and expanded libraries that include
     utility classes, Google's collections, I/O classes, and
@@ -32,7 +33,7 @@
     </dependency>
     <dependency>
       <groupId>org.checkerframework</groupId>
-      <artifactId>checker-compat-qual</artifactId>
+      <artifactId>checker-qual</artifactId>
     </dependency>
     <dependency>
       <groupId>com.google.errorprone</groupId>
@@ -90,42 +91,6 @@
       </plugin>
       <plugin>
         <artifactId>maven-compiler-plugin</artifactId>
-        <executions>
-          <execution>
-            <!--
-                 The execution named default-compile happens first, regardless
-                 of the order of the executions in the source file. So, because
-                 Java8Usage is a dependency of the main sources, we need to call
-                 its compilation "default-compile," even though it's the special
-                 case.
-            -->
-            <id>default-compile</id>
-            <phase>compile</phase>
-            <goals>
-              <goal>compile</goal>
-            </goals>
-            <configuration>
-              <includes>
-                <include>**/Java8Usage.java</include>
-              </includes>
-              <!-- -source 8 -target 8 is a no-op in the mainline but matters in the backport. -->
-              <source>8</source>
-              <target>8</target>
-            </configuration>
-          </execution>
-          <execution>
-            <id>main-compile</id>
-            <phase>compile</phase>
-            <goals>
-              <goal>compile</goal>
-            </goals>
-            <configuration>
-              <excludes>
-                <exclude>**/Java8Usage.java</exclude>
-              </excludes>
-            </configuration>
-          </execution>
-        </executions>
       </plugin>
       <plugin>
         <artifactId>maven-source-plugin</artifactId>
@@ -164,7 +129,7 @@
           <!-- excludePackageNames requires specification of packages separately from "all subpackages".
                https://issues.apache.org/jira/browse/MJAVADOC-584 -->
           <excludePackageNames>
-            com.google.common.base.internal,com.google.common.base.internal.*,com.google.thirdparty.publicsuffix,com.google.thirdparty.publicsuffix.*,com.oracle.*,com.sun.*,java.*,javax.*,jdk,jdk.*,org.*,sun.*
+            com.azul.tooling.in,com.google.common.base.internal,com.google.common.base.internal.*,com.google.thirdparty.publicsuffix,com.google.thirdparty.publicsuffix.*,com.oracle.*,com.sun.*,java.*,javax.*,jdk,jdk.*,org.*,sun.*
           </excludePackageNames>
           <!-- Ignore some tags that are found in Java 11 sources but not recognized... under -source 8, I think it was? I can no longer reproduce the failure. -->
           <tags>
diff --git a/android/guava/src/com/google/common/base/Absent.java b/android/guava/src/com/google/common/base/Absent.java
index 86aec0516d26..f96136b5efac 100644
--- a/android/guava/src/com/google/common/base/Absent.java
+++ b/android/guava/src/com/google/common/base/Absent.java
@@ -19,10 +19,11 @@
 import com.google.common.annotations.GwtCompatible;
 import java.util.Collections;
 import java.util.Set;
-import org.checkerframework.checker.nullness.compatqual.NullableDecl;
+import javax.annotation.CheckForNull;
 
 /** Implementation of an {@link Optional} not containing a reference. */
 @GwtCompatible
+@ElementTypesAreNonnullByDefault
 final class Absent<T> extends Optional<T> {
   static final Absent<Object> INSTANCE = new Absent<>();
 
@@ -61,7 +62,7 @@ public T or(Supplier<? extends T> supplier) {
   }
 
   @Override
-  @NullableDecl
+  @CheckForNull
   public T orNull() {
     return null;
   }
@@ -78,7 +79,7 @@ public <V> Optional<V> transform(Function<? super T, V> function) {
   }
 
   @Override
-  public boolean equals(@NullableDecl Object object) {
+  public boolean equals(@CheckForNull Object object) {
     return object == this;
   }
 
diff --git a/android/guava/src/com/google/common/base/AbstractIterator.java b/android/guava/src/com/google/common/base/AbstractIterator.java
index f6f521e904a5..bb0a1d324978 100644
--- a/android/guava/src/com/google/common/base/AbstractIterator.java
+++ b/android/guava/src/com/google/common/base/AbstractIterator.java
@@ -14,20 +14,23 @@
 
 package com.google.common.base;
 
+import static com.google.common.base.NullnessCasts.uncheckedCastNullableTToT;
 import static com.google.common.base.Preconditions.checkState;
 
 import com.google.common.annotations.GwtCompatible;
 import com.google.errorprone.annotations.CanIgnoreReturnValue;
 import java.util.Iterator;
 import java.util.NoSuchElementException;
-import org.checkerframework.checker.nullness.compatqual.NullableDecl;
+import javax.annotation.CheckForNull;
+import org.checkerframework.checker.nullness.qual.Nullable;
 
 /**
  * Note this class is a copy of {@link com.google.common.collect.AbstractIterator} (for dependency
  * reasons).
  */
 @GwtCompatible
-abstract class AbstractIterator<T> implements Iterator<T> {
+@ElementTypesAreNonnullByDefault
+abstract class AbstractIterator<T extends @Nullable Object> implements Iterator<T> {
   private State state = State.NOT_READY;
 
   protected AbstractIterator() {}
@@ -39,12 +42,13 @@ private enum State {
     FAILED,
   }
 
-  @NullableDecl private T next;
+  @CheckForNull private T next;
 
+  @CheckForNull
   protected abstract T computeNext();
 
   @CanIgnoreReturnValue
-  @NullableDecl
+  @CheckForNull
   protected final T endOfData() {
     state = State.DONE;
     return null;
@@ -74,12 +78,14 @@ private boolean tryToComputeNext() {
   }
 
   @Override
+  @ParametricNullness
   public final T next() {
     if (!hasNext()) {
       throw new NoSuchElementException();
     }
     state = State.NOT_READY;
-    T result = next;
+    // Safe because hasNext() ensures that tryToComputeNext() has put a T into `next`.
+    T result = uncheckedCastNullableTToT(next);
     next = null;
     return result;
   }
diff --git a/android/guava/src/com/google/common/base/Ascii.java b/android/guava/src/com/google/common/base/Ascii.java
index 3a9558016de4..0c651bb27be4 100644
--- a/android/guava/src/com/google/common/base/Ascii.java
+++ b/android/guava/src/com/google/common/base/Ascii.java
@@ -37,6 +37,7 @@
  * @since 7.0
  */
 @GwtCompatible
+@ElementTypesAreNonnullByDefault
 public final class Ascii {
 
   private Ascii() {}
@@ -439,7 +440,7 @@ public static String toLowerCase(CharSequence chars) {
   }
 
   /**
-   * If the argument is an {@linkplain #isUpperCase(char) uppercase ASCII character} returns the
+   * If the argument is an {@linkplain #isUpperCase(char) uppercase ASCII character}, returns the
    * lowercase equivalent. Otherwise returns the argument.
    */
   public static char toLowerCase(char c) {
@@ -487,7 +488,7 @@ public static String toUpperCase(CharSequence chars) {
   }
 
   /**
-   * If the argument is a {@linkplain #isLowerCase(char) lowercase ASCII character} returns the
+   * If the argument is a {@linkplain #isLowerCase(char) lowercase ASCII character}, returns the
    * uppercase equivalent. Otherwise returns the argument.
    */
   public static char toUpperCase(char c) {
diff --git a/android/guava/src/com/google/common/base/CaseFormat.java b/android/guava/src/com/google/common/base/CaseFormat.java
index 5e24bc901b63..7b393ebd7e0f 100644
--- a/android/guava/src/com/google/common/base/CaseFormat.java
+++ b/android/guava/src/com/google/common/base/CaseFormat.java
@@ -15,10 +15,11 @@
 package com.google.common.base;
 
 import static com.google.common.base.Preconditions.checkNotNull;
+import static java.util.Objects.requireNonNull;
 
 import com.google.common.annotations.GwtCompatible;
 import java.io.Serializable;
-import org.checkerframework.checker.nullness.compatqual.NullableDecl;
+import javax.annotation.CheckForNull;
 
 /**
  * Utility class for converting between various ASCII case formats. Behavior is undefined for
@@ -28,6 +29,7 @@
  * @since 1.0
  */
 @GwtCompatible
+@ElementTypesAreNonnullByDefault
 public enum CaseFormat {
   /** Hyphenated variable naming convention, e.g., "lower-hyphen". */
   LOWER_HYPHEN(CharMatcher.is('-'), "-") {
@@ -138,14 +140,14 @@ String convert(CaseFormat format, String s) {
         out = new StringBuilder(s.length() + 4 * format.wordSeparator.length());
         out.append(format.normalizeFirstWord(s.substring(i, j)));
       } else {
-        out.append(format.normalizeWord(s.substring(i, j)));
+        requireNonNull(out).append(format.normalizeWord(s.substring(i, j)));
       }
       out.append(format.wordSeparator);
       i = j + wordSeparator.length();
     }
     return (i == 0)
         ? format.normalizeFirstWord(s)
-        : out.append(format.normalizeWord(s.substring(i))).toString();
+        : requireNonNull(out).append(format.normalizeWord(s.substring(i))).toString();
   }
 
   /**
@@ -179,7 +181,7 @@ protected String doBackward(String s) {
     }
 
     @Override
-    public boolean equals(@NullableDecl Object object) {
+    public boolean equals(@CheckForNull Object object) {
       if (object instanceof StringConverter) {
         StringConverter that = (StringConverter) object;
         return sourceFormat.equals(that.sourceFormat) && targetFormat.equals(that.targetFormat);
diff --git a/android/guava/src/com/google/common/base/CharMatcher.java b/android/guava/src/com/google/common/base/CharMatcher.java
index e17db17dad12..2a2a89447890 100644
--- a/android/guava/src/com/google/common/base/CharMatcher.java
+++ b/android/guava/src/com/google/common/base/CharMatcher.java
@@ -61,6 +61,7 @@
  * @since 1.0
  */
 @GwtCompatible(emulated = true)
+@ElementTypesAreNonnullByDefault
 public abstract class CharMatcher implements Predicate<Character> {
   /*
    *           N777777777NO
@@ -1460,10 +1461,10 @@ private static final class Invisible extends RangesMatcher {
     // [[[:Zs:][:Zl:][:Zp:][:Cc:][:Cf:][:Cs:][:Co:]]&[\u0000-\uFFFF]]
     // with the "Abbreviate" option, and get the ranges from there.
     private static final String RANGE_STARTS =
-        "\u0000\u007f\u00ad\u0600\u061c\u06dd\u070f\u08e2\u1680\u180e\u2000\u2028\u205f\u2066"
+        "\u0000\u007f\u00ad\u0600\u061c\u06dd\u070f\u0890\u08e2\u1680\u180e\u2000\u2028\u205f\u2066"
             + "\u3000\ud800\ufeff\ufff9";
     private static final String RANGE_ENDS = // inclusive ends
-        "\u0020\u00a0\u00ad\u0605\u061c\u06dd\u070f\u08e2\u1680\u180e\u200f\u202f\u2064\u206f"
+        "\u0020\u00a0\u00ad\u0605\u061c\u06dd\u070f\u0891\u08e2\u1680\u180e\u200f\u202f\u2064\u206f"
             + "\u3000\uf8ff\ufeff\ufffb";
 
     static final Invisible INSTANCE = new Invisible();
diff --git a/android/guava/src/com/google/common/base/Charsets.java b/android/guava/src/com/google/common/base/Charsets.java
index 2c9563d769c8..7aebea826c78 100644
--- a/android/guava/src/com/google/common/base/Charsets.java
+++ b/android/guava/src/com/google/common/base/Charsets.java
@@ -31,6 +31,7 @@
  * @since 1.0
  */
 @GwtCompatible(emulated = true)
+@ElementTypesAreNonnullByDefault
 public final class Charsets {
   private Charsets() {}
 
diff --git a/android/guava/src/com/google/common/base/CommonMatcher.java b/android/guava/src/com/google/common/base/CommonMatcher.java
index 6d14c6bc2630..d63b46b5d48f 100644
--- a/android/guava/src/com/google/common/base/CommonMatcher.java
+++ b/android/guava/src/com/google/common/base/CommonMatcher.java
@@ -22,6 +22,7 @@
  * javadoc for details.
  */
 @GwtCompatible
+@ElementTypesAreNonnullByDefault
 abstract class CommonMatcher {
   public abstract boolean matches();
 
diff --git a/android/guava/src/com/google/common/base/CommonPattern.java b/android/guava/src/com/google/common/base/CommonPattern.java
index 6be5b01408aa..c425d52609d6 100644
--- a/android/guava/src/com/google/common/base/CommonPattern.java
+++ b/android/guava/src/com/google/common/base/CommonPattern.java
@@ -22,6 +22,7 @@
  * javadoc for details.
  */
 @GwtCompatible
+@ElementTypesAreNonnullByDefault
 abstract class CommonPattern {
   public abstract CommonMatcher matcher(CharSequence t);
 
diff --git a/android/guava/src/com/google/common/base/Converter.java b/android/guava/src/com/google/common/base/Converter.java
index ea86bb69fde5..422480d164a2 100644
--- a/android/guava/src/com/google/common/base/Converter.java
+++ b/android/guava/src/com/google/common/base/Converter.java
@@ -14,16 +14,19 @@
 
 package com.google.common.base;
 
+import static com.google.common.base.NullnessCasts.uncheckedCastNullableTToT;
 import static com.google.common.base.Preconditions.checkNotNull;
 
 import com.google.common.annotations.GwtCompatible;
 import com.google.errorprone.annotations.CanIgnoreReturnValue;
+import com.google.errorprone.annotations.CheckReturnValue;
 import com.google.errorprone.annotations.ForOverride;
+import com.google.errorprone.annotations.InlineMe;
 import com.google.errorprone.annotations.concurrent.LazyInit;
 import com.google.j2objc.annotations.RetainedWith;
 import java.io.Serializable;
 import java.util.Iterator;
-import org.checkerframework.checker.nullness.compatqual.NullableDecl;
+import javax.annotation.CheckForNull;
 
 /**
  * A function from {@code A} to {@code B} with an associated <i>reverse</i> function from {@code B}
@@ -113,11 +116,36 @@
  * @since 16.0
  */
 @GwtCompatible
+@ElementTypesAreNonnullByDefault
+/*
+ * 1. The type parameter is <T> rather than <T extends @Nullable> so that we can use T in the
+ * doForward and doBackward methods to indicate that the parameter cannot be null. (We also take
+ * advantage of that for convertAll, as discussed on that method.)
+ *
+ * 2. The supertype of this class could be `Function<@Nullable A, @Nullable B>`, since
+ * Converter.apply (like Converter.convert) is capable of accepting null inputs. However, a
+ * supertype of `Function<A, B>` turns out to be massively more useful to callers in practice: They
+ * want their output to be non-null in operations like `stream.map(myConverter)`, and we can
+ * guarantee that as long as we also require the input type to be non-null[*] (which is a
+ * requirement that existing callers already fulfill).
+ *
+ * Disclaimer: Part of the reason that callers are so well adapted to `Function<A, B>` may be that
+ * that is how the signature looked even prior to this comment! So naturally any change can break
+ * existing users, but it can't *fix* existing users because any users who needed
+ * `Function<@Nullable A, @Nullable B>` already had to find a workaround. Still, there is a *ton* of
+ * fallout from trying to switch. I would be shocked if the switch would offer benefits to anywhere
+ * near enough users to justify the costs.
+ *
+ * Fortunately, if anyone does want to use a Converter as a `Function<@Nullable A, @Nullable B>`,
+ * it's easy to get one: `converter::convert`.
+ *
+ * [*] In annotating this class, we're ignoring LegacyConverter.
+ */
 public abstract class Converter<A, B> implements Function<A, B> {
   private final boolean handleNullAutomatically;
 
   // We lazily cache the reverse view to avoid allocating on every call to reverse().
-  @LazyInit @RetainedWith @NullableDecl private transient Converter<B, A> reverse;
+  @LazyInit @RetainedWith @CheckForNull private transient Converter<B, A> reverse;
 
   /** Constructor for use by subclasses. */
   protected Converter() {
@@ -164,31 +192,67 @@ protected Converter() {
    * @return the converted value; is null <i>if and only if</i> {@code a} is null
    */
   @CanIgnoreReturnValue
-  @NullableDecl
-  public final B convert(@NullableDecl A a) {
+  @CheckForNull
+  public final B convert(@CheckForNull A a) {
     return correctedDoForward(a);
   }
 
-  @NullableDecl
-  B correctedDoForward(@NullableDecl A a) {
+  @CheckForNull
+  B correctedDoForward(@CheckForNull A a) {
     if (handleNullAutomatically) {
       // TODO(kevinb): we shouldn't be checking for a null result at runtime. Assert?
       return a == null ? null : checkNotNull(doForward(a));
     } else {
-      return doForward(a);
+      return unsafeDoForward(a);
     }
   }
 
-  @NullableDecl
-  A correctedDoBackward(@NullableDecl B b) {
+  @CheckForNull
+  A correctedDoBackward(@CheckForNull B b) {
     if (handleNullAutomatically) {
       // TODO(kevinb): we shouldn't be checking for a null result at runtime. Assert?
       return b == null ? null : checkNotNull(doBackward(b));
     } else {
-      return doBackward(b);
+      return unsafeDoBackward(b);
     }
   }
 
+  /*
+   * LegacyConverter violates the contract of Converter by allowing its doForward and doBackward
+   * methods to accept null. We could avoid having unchecked casts in Converter.java itself if we
+   * could perform a cast to LegacyConverter, but we can't because it's an internal-only class.
+   *
+   * TODO(cpovirk): So make it part of the open-source build, albeit package-private there?
+   *
+   * So we use uncheckedCastNullableTToT here. This is a weird usage of that method: The method is
+   * documented as being for use with type parameters that have parametric nullness. But Converter's
+   * type parameters do not. Still, we use it here so that we can suppress a warning at a smaller
+   * level than the whole method but without performing a runtime null check. That way, we can still
+   * pass null inputs to LegacyConverter, and it can violate the contract of Converter.
+   *
+   * TODO(cpovirk): Could this be simplified if we modified implementations of LegacyConverter to
+   * override methods (probably called "unsafeDoForward" and "unsafeDoBackward") with the same
+   * signatures as the methods below, rather than overriding the same doForward and doBackward
+   * methods as implementations of normal converters do?
+   *
+   * But no matter what we do, it's worth remembering that the resulting code is going to be unsound
+   * in the presence of LegacyConverter, at least in the case of users who view the converter as a
+   * Function<A, B> or who call convertAll (and for any checkers that apply @PolyNull-like semantics
+   * to Converter.convert). So maybe we don't want to think too hard about how to prevent our
+   * checkers from issuing errors related to LegacyConverter, since it turns out that
+   * LegacyConverter does violate the assumptions we make elsewhere.
+   */
+
+  @CheckForNull
+  private B unsafeDoForward(@CheckForNull A a) {
+    return doForward(uncheckedCastNullableTToT(a));
+  }
+
+  @CheckForNull
+  private A unsafeDoBackward(@CheckForNull B b) {
+    return doBackward(uncheckedCastNullableTToT(b));
+  }
+
   /**
    * Returns an iterable that applies {@code convert} to each element of {@code fromIterable}. The
    * conversion is done lazily.
@@ -198,7 +262,17 @@ A correctedDoBackward(@NullableDecl B b) {
    * element.
    */
   @CanIgnoreReturnValue
-  public Iterable<B> convertAll(final Iterable<? extends A> fromIterable) {
+  /*
+   * Just as Converter could implement `Function<@Nullable A, @Nullable B>` instead of `Function<A,
+   * B>`, convertAll could accept and return iterables with nullable element types. In both cases,
+   * we've chosen to instead use a signature that benefits existing users -- and is still safe.
+   *
+   * For convertAll, I haven't looked as closely at *how* much existing users benefit, so we should
+   * keep an eye out for problems that new users encounter. Note also that convertAll could support
+   * both use cases by using @PolyNull. (By contrast, we can't use @PolyNull for our superinterface
+   * (`implements Function<@PolyNull A, @PolyNull B>`), at least as far as I know.)
+   */
+  public Iterable<B> convertAll(Iterable<? extends A> fromIterable) {
     checkNotNull(fromIterable, "fromIterable");
     return new Iterable<B>() {
       @Override
@@ -212,6 +286,8 @@ public boolean hasNext() {
           }
 
           @Override
+          @SuppressWarnings("nullness") // See code comments on convertAll and Converter.apply.
+          @CheckForNull
           public B next() {
             return convert(fromIterator.next());
           }
@@ -233,7 +309,7 @@ public void remove() {
    *
    * <p><b>Note:</b> you should not override this method. It is non-final for legacy reasons.
    */
-  @CanIgnoreReturnValue
+  @CheckReturnValue
   public Converter<B, A> reverse() {
     Converter<B, A> result = reverse;
     return (result == null) ? reverse = new ReverseConverter<>(this) : result;
@@ -265,14 +341,14 @@ protected B doBackward(A a) {
     }
 
     @Override
-    @NullableDecl
-    A correctedDoForward(@NullableDecl B b) {
+    @CheckForNull
+    A correctedDoForward(@CheckForNull B b) {
       return original.correctedDoBackward(b);
     }
 
     @Override
-    @NullableDecl
-    B correctedDoBackward(@NullableDecl A a) {
+    @CheckForNull
+    B correctedDoBackward(@CheckForNull A a) {
       return original.correctedDoForward(a);
     }
 
@@ -282,7 +358,7 @@ public Converter<A, B> reverse() {
     }
 
     @Override
-    public boolean equals(@NullableDecl Object object) {
+    public boolean equals(@CheckForNull Object object) {
       if (object instanceof ReverseConverter) {
         ReverseConverter<?, ?> that = (ReverseConverter<?, ?>) object;
         return this.original.equals(that.original);
@@ -347,19 +423,19 @@ protected A doBackward(C c) {
     }
 
     @Override
-    @NullableDecl
-    C correctedDoForward(@NullableDecl A a) {
+    @CheckForNull
+    C correctedDoForward(@CheckForNull A a) {
       return second.correctedDoForward(first.correctedDoForward(a));
     }
 
     @Override
-    @NullableDecl
-    A correctedDoBackward(@NullableDecl C c) {
+    @CheckForNull
+    A correctedDoBackward(@CheckForNull C c) {
       return first.correctedDoBackward(second.correctedDoBackward(c));
     }
 
     @Override
-    public boolean equals(@NullableDecl Object object) {
+    public boolean equals(@CheckForNull Object object) {
       if (object instanceof ConverterComposition) {
         ConverterComposition<?, ?, ?> that = (ConverterComposition<?, ?, ?>) object;
         return this.first.equals(that.first) && this.second.equals(that.second);
@@ -386,8 +462,40 @@ public String toString() {
   @Deprecated
   @Override
   @CanIgnoreReturnValue
-  @NullableDecl
-  public final B apply(@NullableDecl A a) {
+  /*
+   * Even though we implement `Function<A, B>` instead of `Function<@Nullable A, @Nullable B>` (as
+   * discussed in a code comment at the top of the class), we declare our override of Function.apply
+   * to accept and return null. This requires a suppression, but it's safe:
+   *
+   * - Callers who use Converter as a Function<A, B> will neither pass null nor have it returned to
+   *   them. (Or, if they're not using nullness checking, they might be able to pass null and thus
+   *   have null returned to them. But our signature isn't making their existing nullness type error
+   *   any worse.)
+   * - In the relatively unlikely event that anyone calls Converter.apply directly, that caller is
+   *   allowed to pass null but is also forced to deal with a potentially null return.
+   * - Perhaps more important than actual *callers* of this method are various tools that look at
+   *   bytecode. Notably, NullPointerTester expects a method to throw NPE when passed null unless it
+   *   is annotated in a way that identifies its parameter type as potentially including null. (And
+   *   this method does not throw NPE -- nor do we want to enact a dangerous change to make it begin
+   *   doing so.) We can even imagine tools that rewrite bytecode to insert null checks before and
+   *   after calling methods with allegedly non-nullable parameters[*]. If we didn't annotate the
+   *   parameter and return type here, then anyone who used such a tool (and managed to pass null to
+   *   this method, presumably because that user doesn't run a normal nullness checker) could see
+   *   NullPointerException.
+   *
+   * [*] Granted, such tools could conceivably be smart enough to recognize that the apply() method
+   * on a a Function<Foo, Bar> should never allow null inputs and never produce null outputs even if
+   * this specific subclass claims otherwise. Such tools might still produce NPE for calls to this
+   * method. And that is one reason that we should be nervous about "lying" by extending Function<A,
+   * B> in the first place. But for now, we're giving it a try, since extending Function<@Nullable
+   * A, @Nullable B> will cause issues *today*, whereas extending Function<A, B> causes problems in
+   * various hypothetical futures. (Plus, a tool that were that smart would likely already introduce
+   * problems with LegacyConverter.)
+   */
+  @SuppressWarnings("nullness")
+  @CheckForNull
+  @InlineMe(replacement = "this.convert(a)")
+  public final B apply(@CheckForNull A a) {
     return convert(a);
   }
 
@@ -403,7 +511,7 @@ public final B apply(@NullableDecl A a) {
    * interchangeable.
    */
   @Override
-  public boolean equals(@NullableDecl Object object) {
+  public boolean equals(@CheckForNull Object object) {
     return super.equals(object);
   }
 
@@ -452,7 +560,7 @@ protected A doBackward(B b) {
     }
 
     @Override
-    public boolean equals(@NullableDecl Object object) {
+    public boolean equals(@CheckForNull Object object) {
       if (object instanceof FunctionBasedConverter) {
         FunctionBasedConverter<?, ?> that = (FunctionBasedConverter<?, ?>) object;
         return this.forwardFunction.equals(that.forwardFunction)
diff --git a/android/guava/src/com/google/common/base/Defaults.java b/android/guava/src/com/google/common/base/Defaults.java
index 00adbdefa12f..5d12343ed241 100644
--- a/android/guava/src/com/google/common/base/Defaults.java
+++ b/android/guava/src/com/google/common/base/Defaults.java
@@ -17,7 +17,7 @@
 import static com.google.common.base.Preconditions.checkNotNull;
 
 import com.google.common.annotations.GwtIncompatible;
-import org.checkerframework.checker.nullness.compatqual.NullableDecl;
+import javax.annotation.CheckForNull;
 
 /**
  * This class provides default values for all Java types, as defined by the JLS.
@@ -26,11 +26,12 @@
  * @since 1.0
  */
 @GwtIncompatible
+@ElementTypesAreNonnullByDefault
 public final class Defaults {
   private Defaults() {}
 
-  private static final Double DOUBLE_DEFAULT = Double.valueOf(0d);
-  private static final Float FLOAT_DEFAULT = Float.valueOf(0f);
+  private static final Double DOUBLE_DEFAULT = 0d;
+  private static final Float FLOAT_DEFAULT = 0f;
 
   /**
    * Returns the default value of {@code type} as defined by JLS --- {@code 0} for numbers, {@code
@@ -38,27 +39,28 @@ private Defaults() {}
    * {@code void}, {@code null} is returned.
    */
   @SuppressWarnings("unchecked")
-  @NullableDecl
+  @CheckForNull
   public static <T> T defaultValue(Class<T> type) {
     checkNotNull(type);
-    if (type == boolean.class) {
-      return (T) Boolean.FALSE;
-    } else if (type == char.class) {
-      return (T) Character.valueOf('\0');
-    } else if (type == byte.class) {
-      return (T) Byte.valueOf((byte) 0);
-    } else if (type == short.class) {
-      return (T) Short.valueOf((short) 0);
-    } else if (type == int.class) {
-      return (T) Integer.valueOf(0);
-    } else if (type == long.class) {
-      return (T) Long.valueOf(0L);
-    } else if (type == float.class) {
-      return (T) FLOAT_DEFAULT;
-    } else if (type == double.class) {
-      return (T) DOUBLE_DEFAULT;
-    } else {
-      return null;
+    if (type.isPrimitive()) {
+      if (type == boolean.class) {
+        return (T) Boolean.FALSE;
+      } else if (type == char.class) {
+        return (T) Character.valueOf('\0');
+      } else if (type == byte.class) {
+        return (T) Byte.valueOf((byte) 0);
+      } else if (type == short.class) {
+        return (T) Short.valueOf((short) 0);
+      } else if (type == int.class) {
+        return (T) Integer.valueOf(0);
+      } else if (type == long.class) {
+        return (T) Long.valueOf(0L);
+      } else if (type == float.class) {
+        return (T) FLOAT_DEFAULT;
+      } else if (type == double.class) {
+        return (T) DOUBLE_DEFAULT;
+      }
     }
+    return null;
   }
 }
diff --git a/android/guava/src/com/google/common/base/ElementTypesAreNonnullByDefault.java b/android/guava/src/com/google/common/base/ElementTypesAreNonnullByDefault.java
new file mode 100644
index 000000000000..890e3a36062a
--- /dev/null
+++ b/android/guava/src/com/google/common/base/ElementTypesAreNonnullByDefault.java
@@ -0,0 +1,41 @@
+/*
+ * Copyright (C) 2021 The Guava Authors
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package com.google.common.base;
+
+import static java.lang.annotation.ElementType.FIELD;
+import static java.lang.annotation.ElementType.METHOD;
+import static java.lang.annotation.ElementType.PARAMETER;
+import static java.lang.annotation.ElementType.TYPE;
+import static java.lang.annotation.RetentionPolicy.RUNTIME;
+
+import com.google.common.annotations.GwtCompatible;
+import java.lang.annotation.Retention;
+import java.lang.annotation.Target;
+import javax.annotation.Nonnull;
+import javax.annotation.meta.TypeQualifierDefault;
+
+/**
+ * Marks all "top-level" types as non-null in a way that is recognized by Kotlin. Note that this
+ * unfortunately includes type-variable usages, so we also provide {@link ParametricNullness} to
+ * "undo" it as best we can.
+ */
+@GwtCompatible
+@Retention(RUNTIME)
+@Target(TYPE)
+@TypeQualifierDefault({FIELD, METHOD, PARAMETER})
+@Nonnull
+@interface ElementTypesAreNonnullByDefault {}
diff --git a/android/guava/src/com/google/common/base/Enums.java b/android/guava/src/com/google/common/base/Enums.java
index 247fa6ed2ecf..5c55b65942cd 100644
--- a/android/guava/src/com/google/common/base/Enums.java
+++ b/android/guava/src/com/google/common/base/Enums.java
@@ -25,7 +25,7 @@
 import java.util.HashMap;
 import java.util.Map;
 import java.util.WeakHashMap;
-import org.checkerframework.checker.nullness.compatqual.NullableDecl;
+import javax.annotation.CheckForNull;
 
 /**
  * Utility methods for working with {@link Enum} instances.
@@ -34,6 +34,7 @@
  * @since 9.0
  */
 @GwtCompatible(emulated = true)
+@ElementTypesAreNonnullByDefault
 public final class Enums {
 
   private Enums() {}
@@ -104,8 +105,8 @@ static <T extends Enum<T>> Map<String, WeakReference<? extends Enum<?>>> getEnum
    *
    * @since 16.0
    */
-  public static <T extends Enum<T>> Converter<String, T> stringConverter(final Class<T> enumClass) {
-    return new StringConverter<T>(enumClass);
+  public static <T extends Enum<T>> Converter<String, T> stringConverter(Class<T> enumClass) {
+    return new StringConverter<>(enumClass);
   }
 
   private static final class StringConverter<T extends Enum<T>> extends Converter<String, T>
@@ -128,7 +129,7 @@ protected String doBackward(T enumValue) {
     }
 
     @Override
-    public boolean equals(@NullableDecl Object object) {
+    public boolean equals(@CheckForNull Object object) {
       if (object instanceof StringConverter) {
         StringConverter<?> that = (StringConverter<?>) object;
         return this.enumClass.equals(that.enumClass);
diff --git a/android/guava/src/com/google/common/base/Equivalence.java b/android/guava/src/com/google/common/base/Equivalence.java
index 436444839f48..1bf7f98998f2 100644
--- a/android/guava/src/com/google/common/base/Equivalence.java
+++ b/android/guava/src/com/google/common/base/Equivalence.java
@@ -19,7 +19,8 @@
 import com.google.common.annotations.GwtCompatible;
 import com.google.errorprone.annotations.ForOverride;
 import java.io.Serializable;
-import org.checkerframework.checker.nullness.compatqual.NullableDecl;
+import javax.annotation.CheckForNull;
+import org.checkerframework.checker.nullness.qual.Nullable;
 
 /**
  * A strategy for determining whether two instances are considered equivalent, and for computing
@@ -38,6 +39,11 @@
  *     source-compatible</a> since 4.0)
  */
 @GwtCompatible
+@ElementTypesAreNonnullByDefault
+/*
+ * The type parameter is <T> rather than <T extends @Nullable> so that we can use T in the
+ * doEquivalent and doHash methods to indicate that the parameter cannot be null.
+ */
 public abstract class Equivalence<T> {
   /** Constructor for use by subclasses. */
   protected Equivalence() {}
@@ -59,7 +65,7 @@ protected Equivalence() {}
    * <p>Note that all calls to {@code equivalent(x, y)} are expected to return the same result as
    * long as neither {@code x} nor {@code y} is modified.
    */
-  public final boolean equivalent(@NullableDecl T a, @NullableDecl T b) {
+  public final boolean equivalent(@CheckForNull T a, @CheckForNull T b) {
     if (a == b) {
       return true;
     }
@@ -70,8 +76,6 @@ public final boolean equivalent(@NullableDecl T a, @NullableDecl T b) {
   }
 
   /**
-   * This method should not be called except by {@link #equivalent}. When {@link #equivalent} calls
-   * this method, {@code a} and {@code b} are guaranteed to be distinct, non-null instances.
    *
    * @since 10.0 (previously, subclasses would override equivalent())
    */
@@ -95,7 +99,7 @@ public final boolean equivalent(@NullableDecl T a, @NullableDecl T b) {
    *   <li>{@code hash(null)} is {@code 0}.
    * </ul>
    */
-  public final int hash(@NullableDecl T t) {
+  public final int hash(@CheckForNull T t) {
     if (t == null) {
       return 0;
     }
@@ -137,7 +141,7 @@ public final int hash(@NullableDecl T t) {
    *
    * @since 10.0
    */
-  public final <F> Equivalence<F> onResultOf(Function<F, ? extends T> function) {
+  public final <F> Equivalence<F> onResultOf(Function<? super F, ? extends @Nullable T> function) {
     return new FunctionalEquivalence<>(function, this);
   }
 
@@ -148,8 +152,44 @@ public final <F> Equivalence<F> onResultOf(Function<F, ? extends T> function) {
    *
    * @since 10.0
    */
-  public final <S extends T> Wrapper<S> wrap(@NullableDecl S reference) {
-    return new Wrapper<S>(this, reference);
+  public final <S extends @Nullable T> Wrapper<S> wrap(@ParametricNullness S reference) {
+    /*
+     * I'm pretty sure that this warning "makes sense" but doesn't indicate a real problem.
+     *
+     * Why it "makes sense": If we pass a `@Nullable Foo`, then we should also pass an
+     * `Equivalence<? super @Nullable Foo>`. And there's no such thing because Equivalence doesn't
+     * permit nullable type arguments.
+     *
+     * Why there's no real problem: Every Equivalence can handle null.
+     *
+     * We could work around this by giving Wrapper 2 type parameters. In the terms of this method,
+     * that would be both the T parameter (from the class) and the S parameter (from this method).
+     * However, such a change would be source-incompatible. (Plus, there's no reason for the S
+     * parameter from the user's perspective, so it would be a wart.)
+     *
+     * We could probably also work around this by making Wrapper non-final and putting the
+     * implementation into a subclass with those 2 type parameters. But we like `final`, if only to
+     * deter users from using mocking frameworks to construct instances. (And could also complicate
+     * serialization, which is discussed more in the next paragraph.)
+     *
+     * We could probably also work around this by having Wrapper accept an instance of a new
+     * WrapperGuts class, which would then be the class that would declare the 2 type parameters.
+     * But that would break deserialization of previously serialized Wrapper instances. And while we
+     * specifically say not to rely on serialization across Guava versions, users sometimes do. So
+     * we'd rather not break them without a good enough reason.
+     *
+     * (We could work around the serialization problem by writing custom serialization code. But
+     * even that helps only the case of serializing with an old version and deserializing with a
+     * new, not vice versa -- unless we introduce WrapperGuts and the logic to handle it today, wait
+     * until "everyone" has picked up a version of Guava with that code, and *then* change to use
+     * WrapperGuts.)
+     *
+     * Anyway, a suppression isn't really a big deal. But I have tried to do some due diligence on
+     * avoiding it :)
+     */
+    @SuppressWarnings("nullness")
+    Wrapper<S> w = new Wrapper<>(this, reference);
+    return w;
   }
 
   /**
@@ -172,17 +212,17 @@ public final <S extends T> Wrapper<S> wrap(@NullableDecl S reference) {
    *
    * @since 10.0
    */
-  public static final class Wrapper<T> implements Serializable {
+  public static final class Wrapper<T extends @Nullable Object> implements Serializable {
     private final Equivalence<? super T> equivalence;
-    @NullableDecl private final T reference;
+    @ParametricNullness private final T reference;
 
-    private Wrapper(Equivalence<? super T> equivalence, @NullableDecl T reference) {
+    private Wrapper(Equivalence<? super T> equivalence, @ParametricNullness T reference) {
       this.equivalence = checkNotNull(equivalence);
       this.reference = reference;
     }
 
     /** Returns the (possibly null) reference wrapped by this instance. */
-    @NullableDecl
+    @ParametricNullness
     public T get() {
       return reference;
     }
@@ -193,7 +233,7 @@ public T get() {
      * equivalence.
      */
     @Override
-    public boolean equals(@NullableDecl Object obj) {
+    public boolean equals(@CheckForNull Object obj) {
       if (obj == this) {
         return true;
       }
@@ -243,10 +283,10 @@ public String toString() {
    * @since 10.0
    */
   @GwtCompatible(serializable = true)
-  public final <S extends T> Equivalence<Iterable<S>> pairwise() {
+  public final <S extends @Nullable T> Equivalence<Iterable<S>> pairwise() {
     // Ideally, the returned equivalence would support Iterable<? extends T>. However,
     // the need for this is so rare that it's not worth making callers deal with the ugly wildcard.
-    return new PairwiseEquivalence<S>(this);
+    return new PairwiseEquivalence<>(this);
   }
 
   /**
@@ -255,27 +295,28 @@ public final <S extends T> Equivalence<Iterable<S>> pairwise() {
    *
    * @since 10.0
    */
-  public final Predicate<T> equivalentTo(@NullableDecl T target) {
+  public final Predicate<@Nullable T> equivalentTo(@CheckForNull T target) {
     return new EquivalentToPredicate<T>(this, target);
   }
 
-  private static final class EquivalentToPredicate<T> implements Predicate<T>, Serializable {
+  private static final class EquivalentToPredicate<T>
+      implements Predicate<@Nullable T>, Serializable {
 
     private final Equivalence<T> equivalence;
-    @NullableDecl private final T target;
+    @CheckForNull private final T target;
 
-    EquivalentToPredicate(Equivalence<T> equivalence, @NullableDecl T target) {
+    EquivalentToPredicate(Equivalence<T> equivalence, @CheckForNull T target) {
       this.equivalence = checkNotNull(equivalence);
       this.target = target;
     }
 
     @Override
-    public boolean apply(@NullableDecl T input) {
+    public boolean apply(@CheckForNull T input) {
       return equivalence.equivalent(input, target);
     }
 
     @Override
-    public boolean equals(@NullableDecl Object obj) {
+    public boolean equals(@CheckForNull Object obj) {
       if (this == obj) {
         return true;
       }
diff --git a/android/guava/src/com/google/common/base/ExtraObjectsMethodsForWeb.java b/android/guava/src/com/google/common/base/ExtraObjectsMethodsForWeb.java
index 21cca2c109d6..677075522028 100644
--- a/android/guava/src/com/google/common/base/ExtraObjectsMethodsForWeb.java
+++ b/android/guava/src/com/google/common/base/ExtraObjectsMethodsForWeb.java
@@ -21,4 +21,5 @@
  * version.
  */
 @GwtCompatible(emulated = true)
+@ElementTypesAreNonnullByDefault
 abstract class ExtraObjectsMethodsForWeb {}
diff --git a/android/guava/src/com/google/common/base/FinalizablePhantomReference.java b/android/guava/src/com/google/common/base/FinalizablePhantomReference.java
index f92057588a30..4f9399669569 100644
--- a/android/guava/src/com/google/common/base/FinalizablePhantomReference.java
+++ b/android/guava/src/com/google/common/base/FinalizablePhantomReference.java
@@ -17,6 +17,7 @@
 import com.google.common.annotations.GwtIncompatible;
 import java.lang.ref.PhantomReference;
 import java.lang.ref.ReferenceQueue;
+import javax.annotation.CheckForNull;
 
 /**
  * Phantom reference with a {@code finalizeReferent()} method which a background thread invokes
@@ -29,6 +30,7 @@
  * @since 2.0
  */
 @GwtIncompatible
+@ElementTypesAreNonnullByDefault
 public abstract class FinalizablePhantomReference<T> extends PhantomReference<T>
     implements FinalizableReference {
   /**
@@ -37,7 +39,7 @@ public abstract class FinalizablePhantomReference<T> extends PhantomReference<T>
    * @param referent to phantom reference
    * @param queue that should finalize the referent
    */
-  protected FinalizablePhantomReference(T referent, FinalizableReferenceQueue queue) {
+  protected FinalizablePhantomReference(@CheckForNull T referent, FinalizableReferenceQueue queue) {
     super(referent, queue.queue);
     queue.cleanUp();
   }
diff --git a/android/guava/src/com/google/common/base/FinalizableReference.java b/android/guava/src/com/google/common/base/FinalizableReference.java
index 848e7ee586d2..73753c9b3520 100644
--- a/android/guava/src/com/google/common/base/FinalizableReference.java
+++ b/android/guava/src/com/google/common/base/FinalizableReference.java
@@ -26,6 +26,7 @@
  */
 @DoNotMock("Use an instance of one of the Finalizable*Reference classes")
 @GwtIncompatible
+@ElementTypesAreNonnullByDefault
 public interface FinalizableReference {
   /**
    * Invoked on a background thread after the referent has been garbage collected unless security
diff --git a/android/guava/src/com/google/common/base/FinalizableReferenceQueue.java b/android/guava/src/com/google/common/base/FinalizableReferenceQueue.java
index 40dfd462b81c..7447b8051d31 100644
--- a/android/guava/src/com/google/common/base/FinalizableReferenceQueue.java
+++ b/android/guava/src/com/google/common/base/FinalizableReferenceQueue.java
@@ -27,7 +27,7 @@
 import java.net.URLClassLoader;
 import java.util.logging.Level;
 import java.util.logging.Logger;
-import org.checkerframework.checker.nullness.compatqual.NullableDecl;
+import javax.annotation.CheckForNull;
 
 /**
  * A reference queue with an associated background thread that dequeues references and invokes
@@ -37,7 +37,7 @@
  * finalized. If this object is garbage collected earlier, the backing thread will not invoke {@code
  * finalizeReferent()} on the remaining references.
  *
- * <p>As an example of how this is used, imagine you have a class {@code MyServer} that creates a a
+ * <p>As an example of how this is used, imagine you have a class {@code MyServer} that creates a
  * {@link java.net.ServerSocket ServerSocket}, and you would like to ensure that the {@code
  * ServerSocket} is closed even if the {@code MyServer} object is garbage-collected without calling
  * its {@code close} method. You <em>could</em> use a finalizer to accomplish this, but that has a
@@ -89,6 +89,7 @@
  * @since 2.0
  */
 @GwtIncompatible
+@ElementTypesAreNonnullByDefault
 public class FinalizableReferenceQueue implements Closeable {
   /*
    * The Finalizer thread keeps a phantom reference to this object. When the client (for example, a
@@ -155,7 +156,7 @@ public class FinalizableReferenceQueue implements Closeable {
   public FinalizableReferenceQueue() {
     // We could start the finalizer lazily, but I'd rather it blow up early.
     queue = new ReferenceQueue<>();
-    frqRef = new PhantomReference<Object>(this, queue);
+    frqRef = new PhantomReference<>(this, queue);
     boolean threadStarted = false;
     try {
       startFinalizer.invoke(null, FinalizableReference.class, queue, frqRef);
@@ -228,7 +229,7 @@ interface FinalizerLoader {
      *
      * @throws SecurityException if we don't have the appropriate privileges
      */
-    @NullableDecl
+    @CheckForNull
     Class<?> loadFinalizer();
   }
 
@@ -242,7 +243,7 @@ static class SystemLoader implements FinalizerLoader {
     @VisibleForTesting static boolean disabled;
 
     @Override
-    @NullableDecl
+    @CheckForNull
     public Class<?> loadFinalizer() {
       if (disabled) {
         return null;
@@ -280,7 +281,7 @@ static class DecoupledLoader implements FinalizerLoader {
             + "issue, or move Guava to your system class path.";
 
     @Override
-    @NullableDecl
+    @CheckForNull
     public Class<?> loadFinalizer() {
       try {
         /*
diff --git a/android/guava/src/com/google/common/base/FinalizableSoftReference.java b/android/guava/src/com/google/common/base/FinalizableSoftReference.java
index 45ecc656c0d4..c0e9b6bae041 100644
--- a/android/guava/src/com/google/common/base/FinalizableSoftReference.java
+++ b/android/guava/src/com/google/common/base/FinalizableSoftReference.java
@@ -17,6 +17,7 @@
 import com.google.common.annotations.GwtIncompatible;
 import java.lang.ref.ReferenceQueue;
 import java.lang.ref.SoftReference;
+import javax.annotation.CheckForNull;
 
 /**
  * Soft reference with a {@code finalizeReferent()} method which a background thread invokes after
@@ -27,6 +28,7 @@
  * @since 2.0
  */
 @GwtIncompatible
+@ElementTypesAreNonnullByDefault
 public abstract class FinalizableSoftReference<T> extends SoftReference<T>
     implements FinalizableReference {
   /**
@@ -35,7 +37,7 @@ public abstract class FinalizableSoftReference<T> extends SoftReference<T>
    * @param referent to softly reference
    * @param queue that should finalize the referent
    */
-  protected FinalizableSoftReference(T referent, FinalizableReferenceQueue queue) {
+  protected FinalizableSoftReference(@CheckForNull T referent, FinalizableReferenceQueue queue) {
     super(referent, queue.queue);
     queue.cleanUp();
   }
diff --git a/android/guava/src/com/google/common/base/FinalizableWeakReference.java b/android/guava/src/com/google/common/base/FinalizableWeakReference.java
index fb3b09bb7dc4..9cca92ed5310 100644
--- a/android/guava/src/com/google/common/base/FinalizableWeakReference.java
+++ b/android/guava/src/com/google/common/base/FinalizableWeakReference.java
@@ -17,6 +17,7 @@
 import com.google.common.annotations.GwtIncompatible;
 import java.lang.ref.ReferenceQueue;
 import java.lang.ref.WeakReference;
+import javax.annotation.CheckForNull;
 
 /**
  * Weak reference with a {@code finalizeReferent()} method which a background thread invokes after
@@ -27,6 +28,7 @@
  * @since 2.0
  */
 @GwtIncompatible
+@ElementTypesAreNonnullByDefault
 public abstract class FinalizableWeakReference<T> extends WeakReference<T>
     implements FinalizableReference {
   /**
@@ -35,7 +37,7 @@ public abstract class FinalizableWeakReference<T> extends WeakReference<T>
    * @param referent to weakly reference
    * @param queue that should finalize the referent
    */
-  protected FinalizableWeakReference(T referent, FinalizableReferenceQueue queue) {
+  protected FinalizableWeakReference(@CheckForNull T referent, FinalizableReferenceQueue queue) {
     super(referent, queue.queue);
     queue.cleanUp();
   }
diff --git a/android/guava/src/com/google/common/base/Function.java b/android/guava/src/com/google/common/base/Function.java
index 05831867fef8..7d633af21c61 100644
--- a/android/guava/src/com/google/common/base/Function.java
+++ b/android/guava/src/com/google/common/base/Function.java
@@ -16,7 +16,8 @@
 
 import com.google.common.annotations.GwtCompatible;
 import com.google.errorprone.annotations.CanIgnoreReturnValue;
-import org.checkerframework.checker.nullness.compatqual.NullableDecl;
+import javax.annotation.CheckForNull;
+import org.checkerframework.checker.nullness.qual.Nullable;
 
 /**
  * Determines an output value based on an input value; a pre-Java-8 version of {@link
@@ -44,7 +45,8 @@
  * @since 2.0
  */
 @GwtCompatible
-public interface Function<F, T> {
+@ElementTypesAreNonnullByDefault
+public interface Function<F extends @Nullable Object, T extends @Nullable Object> {
   /**
    * Returns the result of applying this function to {@code input}. This method is <i>generally
    * expected</i>, but not absolutely required, to have the following properties:
@@ -60,8 +62,8 @@ public interface Function<F, T> {
    *     arguments
    */
   @CanIgnoreReturnValue // TODO(kevinb): remove this
-  @NullableDecl
-  T apply(@NullableDecl F input);
+  @ParametricNullness
+  T apply(@ParametricNullness F input);
 
   /**
    * <i>May</i> return {@code true} if {@code object} is a {@code Function} that behaves identically
@@ -75,5 +77,5 @@ public interface Function<F, T> {
    * disappear. It is best not to depend on it.
    */
   @Override
-  boolean equals(@NullableDecl Object object);
+  boolean equals(@CheckForNull Object object);
 }
diff --git a/android/guava/src/com/google/common/base/FunctionalEquivalence.java b/android/guava/src/com/google/common/base/FunctionalEquivalence.java
index 17dd40078124..4383f4f36c1a 100644
--- a/android/guava/src/com/google/common/base/FunctionalEquivalence.java
+++ b/android/guava/src/com/google/common/base/FunctionalEquivalence.java
@@ -19,7 +19,8 @@
 import com.google.common.annotations.Beta;
 import com.google.common.annotations.GwtCompatible;
 import java.io.Serializable;
-import org.checkerframework.checker.nullness.compatqual.NullableDecl;
+import javax.annotation.CheckForNull;
+import org.checkerframework.checker.nullness.qual.Nullable;
 
 /**
  * Equivalence applied on functional result.
@@ -29,14 +30,16 @@
  */
 @Beta
 @GwtCompatible
+@ElementTypesAreNonnullByDefault
 final class FunctionalEquivalence<F, T> extends Equivalence<F> implements Serializable {
 
   private static final long serialVersionUID = 0;
 
-  private final Function<F, ? extends T> function;
+  private final Function<? super F, ? extends @Nullable T> function;
   private final Equivalence<T> resultEquivalence;
 
-  FunctionalEquivalence(Function<F, ? extends T> function, Equivalence<T> resultEquivalence) {
+  FunctionalEquivalence(
+      Function<? super F, ? extends @Nullable T> function, Equivalence<T> resultEquivalence) {
     this.function = checkNotNull(function);
     this.resultEquivalence = checkNotNull(resultEquivalence);
   }
@@ -52,7 +55,7 @@ protected int doHash(F a) {
   }
 
   @Override
-  public boolean equals(@NullableDecl Object obj) {
+  public boolean equals(@CheckForNull Object obj) {
     if (obj == this) {
       return true;
     }
diff --git a/android/guava/src/com/google/common/base/Functions.java b/android/guava/src/com/google/common/base/Functions.java
index 805f15c73727..78785047eb82 100644
--- a/android/guava/src/com/google/common/base/Functions.java
+++ b/android/guava/src/com/google/common/base/Functions.java
@@ -14,13 +14,15 @@
 
 package com.google.common.base;
 
+import static com.google.common.base.NullnessCasts.uncheckedCastNullableTToT;
 import static com.google.common.base.Preconditions.checkArgument;
 import static com.google.common.base.Preconditions.checkNotNull;
 
 import com.google.common.annotations.GwtCompatible;
 import java.io.Serializable;
 import java.util.Map;
-import org.checkerframework.checker.nullness.compatqual.NullableDecl;
+import javax.annotation.CheckForNull;
+import org.checkerframework.checker.nullness.qual.Nullable;
 
 /**
  * Static utility methods pertaining to {@code com.google.common.base.Function} instances; see that
@@ -36,6 +38,7 @@
  * @since 2.0
  */
 @GwtCompatible
+@ElementTypesAreNonnullByDefault
 public final class Functions {
   private Functions() {}
 
@@ -79,17 +82,17 @@ public String toString() {
   /** Returns the identity function. */
   // implementation is "fully variant"; E has become a "pass-through" type
   @SuppressWarnings("unchecked")
-  public static <E> Function<E, E> identity() {
+  public static <E extends @Nullable Object> Function<E, E> identity() {
     return (Function<E, E>) IdentityFunction.INSTANCE;
   }
 
   // enum singleton pattern
-  private enum IdentityFunction implements Function<Object, Object> {
+  private enum IdentityFunction implements Function<@Nullable Object, @Nullable Object> {
     INSTANCE;
 
     @Override
-    @NullableDecl
-    public Object apply(@NullableDecl Object o) {
+    @CheckForNull
+    public Object apply(@CheckForNull Object o) {
       return o;
     }
 
@@ -112,7 +115,8 @@ public String toString() {
    * key (instead of an exception being thrown), you can use the method reference {@code map::get}
    * instead.
    */
-  public static <K, V> Function<K, V> forMap(Map<K, V> map) {
+  public static <K extends @Nullable Object, V extends @Nullable Object> Function<K, V> forMap(
+      Map<K, V> map) {
     return new FunctionForMapNoDefault<>(map);
   }
 
@@ -129,12 +133,14 @@ public static <K, V> Function<K, V> forMap(Map<K, V> map) {
    * @return function that returns {@code map.get(a)} when {@code a} is a key, or {@code
    *     defaultValue} otherwise
    */
-  public static <K, V> Function<K, V> forMap(
-      Map<K, ? extends V> map, @NullableDecl V defaultValue) {
+  public static <K extends @Nullable Object, V extends @Nullable Object> Function<K, V> forMap(
+      Map<K, ? extends V> map, @ParametricNullness V defaultValue) {
     return new ForMapWithDefault<>(map, defaultValue);
   }
 
-  private static class FunctionForMapNoDefault<K, V> implements Function<K, V>, Serializable {
+  private static class FunctionForMapNoDefault<
+          K extends @Nullable Object, V extends @Nullable Object>
+      implements Function<K, V>, Serializable {
     final Map<K, V> map;
 
     FunctionForMapNoDefault(Map<K, V> map) {
@@ -142,14 +148,16 @@ private static class FunctionForMapNoDefault<K, V> implements Function<K, V>, Se
     }
 
     @Override
-    public V apply(@NullableDecl K key) {
+    @ParametricNullness
+    public V apply(@ParametricNullness K key) {
       V result = map.get(key);
       checkArgument(result != null || map.containsKey(key), "Key '%s' not present in map", key);
-      return result;
+      // The unchecked cast is safe because of the containsKey check.
+      return uncheckedCastNullableTToT(result);
     }
 
     @Override
-    public boolean equals(@NullableDecl Object o) {
+    public boolean equals(@CheckForNull Object o) {
       if (o instanceof FunctionForMapNoDefault) {
         FunctionForMapNoDefault<?, ?> that = (FunctionForMapNoDefault<?, ?>) o;
         return map.equals(that.map);
@@ -170,23 +178,28 @@ public String toString() {
     private static final long serialVersionUID = 0;
   }
 
-  private static class ForMapWithDefault<K, V> implements Function<K, V>, Serializable {
+  private static class ForMapWithDefault<K extends @Nullable Object, V extends @Nullable Object>
+      implements Function<K, V>, Serializable {
     final Map<K, ? extends V> map;
-    @NullableDecl final V defaultValue;
+    @ParametricNullness final V defaultValue;
 
-    ForMapWithDefault(Map<K, ? extends V> map, @NullableDecl V defaultValue) {
+    ForMapWithDefault(Map<K, ? extends V> map, @ParametricNullness V defaultValue) {
       this.map = checkNotNull(map);
       this.defaultValue = defaultValue;
     }
 
     @Override
-    public V apply(@NullableDecl K key) {
+    @ParametricNullness
+    public V apply(@ParametricNullness K key) {
       V result = map.get(key);
-      return (result != null || map.containsKey(key)) ? result : defaultValue;
+      // The unchecked cast is safe because of the containsKey check.
+      return (result != null || map.containsKey(key))
+          ? uncheckedCastNullableTToT(result)
+          : defaultValue;
     }
 
     @Override
-    public boolean equals(@NullableDecl Object o) {
+    public boolean equals(@CheckForNull Object o) {
       if (o instanceof ForMapWithDefault) {
         ForMapWithDefault<?, ?> that = (ForMapWithDefault<?, ?>) o;
         return map.equals(that.map) && Objects.equal(defaultValue, that.defaultValue);
@@ -220,11 +233,14 @@ public String toString() {
    * @return the composition of {@code f} and {@code g}
    * @see <a href="//en.wikipedia.org/wiki/Function_composition">function composition</a>
    */
-  public static <A, B, C> Function<A, C> compose(Function<B, C> g, Function<A, ? extends B> f) {
+  public static <A extends @Nullable Object, B extends @Nullable Object, C extends @Nullable Object>
+      Function<A, C> compose(Function<B, C> g, Function<A, ? extends B> f) {
     return new FunctionComposition<>(g, f);
   }
 
-  private static class FunctionComposition<A, B, C> implements Function<A, C>, Serializable {
+  private static class FunctionComposition<
+          A extends @Nullable Object, B extends @Nullable Object, C extends @Nullable Object>
+      implements Function<A, C>, Serializable {
     private final Function<B, C> g;
     private final Function<A, ? extends B> f;
 
@@ -234,12 +250,13 @@ public FunctionComposition(Function<B, C> g, Function<A, ? extends B> f) {
     }
 
     @Override
-    public C apply(@NullableDecl A a) {
+    @ParametricNullness
+    public C apply(@ParametricNullness A a) {
       return g.apply(f.apply(a));
     }
 
     @Override
-    public boolean equals(@NullableDecl Object obj) {
+    public boolean equals(@CheckForNull Object obj) {
       if (obj instanceof FunctionComposition) {
         FunctionComposition<?, ?, ?> that = (FunctionComposition<?, ?, ?>) obj;
         return f.equals(that.f) && g.equals(that.g);
@@ -269,12 +286,14 @@ public String toString() {
    *
    * <p><b>Java 8 users:</b> use the method reference {@code predicate::test} instead.
    */
-  public static <T> Function<T, Boolean> forPredicate(Predicate<T> predicate) {
-    return new PredicateFunction<T>(predicate);
+  public static <T extends @Nullable Object> Function<T, Boolean> forPredicate(
+      Predicate<T> predicate) {
+    return new PredicateFunction<>(predicate);
   }
 
   /** @see Functions#forPredicate */
-  private static class PredicateFunction<T> implements Function<T, Boolean>, Serializable {
+  private static class PredicateFunction<T extends @Nullable Object>
+      implements Function<T, Boolean>, Serializable {
     private final Predicate<T> predicate;
 
     private PredicateFunction(Predicate<T> predicate) {
@@ -282,12 +301,12 @@ private PredicateFunction(Predicate<T> predicate) {
     }
 
     @Override
-    public Boolean apply(@NullableDecl T t) {
+    public Boolean apply(@ParametricNullness T t) {
       return predicate.apply(t);
     }
 
     @Override
-    public boolean equals(@NullableDecl Object obj) {
+    public boolean equals(@CheckForNull Object obj) {
       if (obj instanceof PredicateFunction) {
         PredicateFunction<?> that = (PredicateFunction<?>) obj;
         return predicate.equals(that.predicate);
@@ -316,24 +335,27 @@ public String toString() {
    * @param value the constant value for the function to return
    * @return a function that always returns {@code value}
    */
-  public static <E> Function<Object, E> constant(@NullableDecl E value) {
-    return new ConstantFunction<E>(value);
+  public static <E extends @Nullable Object> Function<@Nullable Object, E> constant(
+      @ParametricNullness E value) {
+    return new ConstantFunction<>(value);
   }
 
-  private static class ConstantFunction<E> implements Function<Object, E>, Serializable {
-    @NullableDecl private final E value;
+  private static class ConstantFunction<E extends @Nullable Object>
+      implements Function<@Nullable Object, E>, Serializable {
+    @ParametricNullness private final E value;
 
-    public ConstantFunction(@NullableDecl E value) {
+    public ConstantFunction(@ParametricNullness E value) {
       this.value = value;
     }
 
     @Override
-    public E apply(@NullableDecl Object from) {
+    @ParametricNullness
+    public E apply(@CheckForNull Object from) {
       return value;
     }
 
     @Override
-    public boolean equals(@NullableDecl Object obj) {
+    public boolean equals(@CheckForNull Object obj) {
       if (obj instanceof ConstantFunction) {
         ConstantFunction<?> that = (ConstantFunction<?>) obj;
         return Objects.equal(value, that.value);
@@ -361,12 +383,14 @@ public String toString() {
    *
    * @since 10.0
    */
-  public static <T> Function<Object, T> forSupplier(Supplier<T> supplier) {
-    return new SupplierFunction<T>(supplier);
+  public static <F extends @Nullable Object, T extends @Nullable Object> Function<F, T> forSupplier(
+      Supplier<T> supplier) {
+    return new SupplierFunction<>(supplier);
   }
 
   /** @see Functions#forSupplier */
-  private static class SupplierFunction<T> implements Function<Object, T>, Serializable {
+  private static class SupplierFunction<F extends @Nullable Object, T extends @Nullable Object>
+      implements Function<F, T>, Serializable {
 
     private final Supplier<T> supplier;
 
@@ -375,14 +399,15 @@ private SupplierFunction(Supplier<T> supplier) {
     }
 
     @Override
-    public T apply(@NullableDecl Object input) {
+    @ParametricNullness
+    public T apply(@ParametricNullness F input) {
       return supplier.get();
     }
 
     @Override
-    public boolean equals(@NullableDecl Object obj) {
+    public boolean equals(@CheckForNull Object obj) {
       if (obj instanceof SupplierFunction) {
-        SupplierFunction<?> that = (SupplierFunction<?>) obj;
+        SupplierFunction<?, ?> that = (SupplierFunction<?, ?>) obj;
         return this.supplier.equals(that.supplier);
       }
       return false;
diff --git a/android/guava/src/com/google/common/base/Java8Compatibility.java b/android/guava/src/com/google/common/base/Java8Compatibility.java
new file mode 100644
index 000000000000..edc8b73bdd10
--- /dev/null
+++ b/android/guava/src/com/google/common/base/Java8Compatibility.java
@@ -0,0 +1,44 @@
+/*
+ * Copyright (C) 2020 The Guava Authors
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file except
+ * in compliance with the License. You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software distributed under the License
+ * is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express
+ * or implied. See the License for the specific language governing permissions and limitations under
+ * the License.
+ */
+
+package com.google.common.base;
+
+import com.google.common.annotations.GwtIncompatible;
+import java.nio.Buffer;
+
+/**
+ * Wrappers around {@link Buffer} methods that are covariantly overridden in Java 9+. See
+ * https://github.com/google/guava/issues/3990
+ */
+@GwtIncompatible
+@ElementTypesAreNonnullByDefault
+final class Java8Compatibility {
+  static void clear(Buffer b) {
+    b.clear();
+  }
+
+  static void flip(Buffer b) {
+    b.flip();
+  }
+
+  static void limit(Buffer b, int limit) {
+    b.limit(limit);
+  }
+
+  static void position(Buffer b, int position) {
+    b.position(position);
+  }
+
+  private Java8Compatibility() {}
+}
diff --git a/android/guava/src/com/google/common/base/Java8Usage.java b/android/guava/src/com/google/common/base/Java8Usage.java
deleted file mode 100755
index 78130cf676d9..000000000000
--- a/android/guava/src/com/google/common/base/Java8Usage.java
+++ /dev/null
@@ -1,45 +0,0 @@
-/*
- * Copyright (C) 2020 The Guava Authors
- *
- * Licensed under the Apache License, Version 2.0 (the "License");
- * you may not use this file except in compliance with the License.
- * You may obtain a copy of the License at
- *
- * http://www.apache.org/licenses/LICENSE-2.0
- *
- * Unless required by applicable law or agreed to in writing, software
- * distributed under the License is distributed on an "AS IS" BASIS,
- * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
- * See the License for the specific language governing permissions and
- * limitations under the License.
- */
-
-package com.google.common.base;
-
-import com.google.errorprone.annotations.CanIgnoreReturnValue;
-
-/**
- * A class that uses a couple Java 8 features but doesn't really do anything. This lets us attempt
- * to load it and log a warning if that fails, giving users advance notice of our dropping Java 8
- * support.
- */
-/*
- * This class should be annotated @GwtCompatible. But if we annotate it @GwtCompatible, then we need
- * to build GwtCompatible.java (-source 7 -target 7 in the Android flavor) before we build
- * Java8Usage.java (-source 8 target 8, which we already need to build before the rest of
- * common.base). We could configure Maven to do that, but it's easier to just skip the annotation.
- */
-final class Java8Usage {
-  @java.lang.annotation.Target(java.lang.annotation.ElementType.TYPE_USE)
-  @java.lang.annotation.Retention(java.lang.annotation.RetentionPolicy.RUNTIME)
-  private @interface SomeTypeAnnotation {}
-
-  @CanIgnoreReturnValue
-  static @SomeTypeAnnotation String performCheck() {
-    Runnable r = () -> {};
-    r.run();
-    return "";
-  }
-
-  private Java8Usage() {}
-}
diff --git a/android/guava/src/com/google/common/base/JdkPattern.java b/android/guava/src/com/google/common/base/JdkPattern.java
index f7791dba6e95..4788398b7c20 100644
--- a/android/guava/src/com/google/common/base/JdkPattern.java
+++ b/android/guava/src/com/google/common/base/JdkPattern.java
@@ -20,6 +20,7 @@
 import java.util.regex.Pattern;
 
 /** A regex pattern implementation which is backed by the {@link Pattern}. */
+@ElementTypesAreNonnullByDefault
 @GwtIncompatible
 final class JdkPattern extends CommonPattern implements Serializable {
   private final Pattern pattern;
diff --git a/android/guava/src/com/google/common/base/Joiner.java b/android/guava/src/com/google/common/base/Joiner.java
index f74f02feba0a..8b29f68f8ad1 100644
--- a/android/guava/src/com/google/common/base/Joiner.java
+++ b/android/guava/src/com/google/common/base/Joiner.java
@@ -15,6 +15,7 @@
 package com.google.common.base;
 
 import static com.google.common.base.Preconditions.checkNotNull;
+import static java.util.Objects.requireNonNull;
 
 import com.google.common.annotations.Beta;
 import com.google.common.annotations.GwtCompatible;
@@ -25,7 +26,8 @@
 import java.util.Iterator;
 import java.util.Map;
 import java.util.Map.Entry;
-import org.checkerframework.checker.nullness.compatqual.NullableDecl;
+import javax.annotation.CheckForNull;
+import org.checkerframework.checker.nullness.qual.Nullable;
 
 /**
  * An object which joins pieces of text (specified as an array, {@link Iterable}, varargs or even a
@@ -63,6 +65,7 @@
  * @since 2.0
  */
 @GwtCompatible
+@ElementTypesAreNonnullByDefault
 public class Joiner {
   /** Returns a joiner which automatically places {@code separator} between consecutive elements. */
   public static Joiner on(String separator) {
@@ -84,12 +87,19 @@ private Joiner(Joiner prototype) {
     this.separator = prototype.separator;
   }
 
+  /*
+   * In this file, we use <? extends @Nullable Object> instead of <?> to work around a Kotlin bug
+   * (see b/189937072 until we file a bug against Kotlin itself). (The two should be equivalent, so
+   * we normally prefer the shorter one.)
+   */
+
   /**
    * Appends the string representation of each of {@code parts}, using the previously configured
    * separator between each, to {@code appendable}.
    */
   @CanIgnoreReturnValue
-  public <A extends Appendable> A appendTo(A appendable, Iterable<?> parts) throws IOException {
+  public <A extends Appendable> A appendTo(A appendable, Iterable<? extends @Nullable Object> parts)
+      throws IOException {
     return appendTo(appendable, parts.iterator());
   }
 
@@ -100,7 +110,8 @@ public <A extends Appendable> A appendTo(A appendable, Iterable<?> parts) throws
    * @since 11.0
    */
   @CanIgnoreReturnValue
-  public <A extends Appendable> A appendTo(A appendable, Iterator<?> parts) throws IOException {
+  public <A extends Appendable> A appendTo(A appendable, Iterator<? extends @Nullable Object> parts)
+      throws IOException {
     checkNotNull(appendable);
     if (parts.hasNext()) {
       appendable.append(toString(parts.next()));
@@ -117,14 +128,18 @@ public <A extends Appendable> A appendTo(A appendable, Iterator<?> parts) throws
    * separator between each, to {@code appendable}.
    */
   @CanIgnoreReturnValue
-  public final <A extends Appendable> A appendTo(A appendable, Object[] parts) throws IOException {
+  public final <A extends Appendable> A appendTo(A appendable, @Nullable Object[] parts)
+      throws IOException {
     return appendTo(appendable, Arrays.asList(parts));
   }
 
   /** Appends to {@code appendable} the string representation of each of the remaining arguments. */
   @CanIgnoreReturnValue
   public final <A extends Appendable> A appendTo(
-      A appendable, @NullableDecl Object first, @NullableDecl Object second, Object... rest)
+      A appendable,
+      @CheckForNull Object first,
+      @CheckForNull Object second,
+      @Nullable Object... rest)
       throws IOException {
     return appendTo(appendable, iterable(first, second, rest));
   }
@@ -135,7 +150,8 @@ public final <A extends Appendable> A appendTo(
    * Iterable)}, except that it does not throw {@link IOException}.
    */
   @CanIgnoreReturnValue
-  public final StringBuilder appendTo(StringBuilder builder, Iterable<?> parts) {
+  public final StringBuilder appendTo(
+      StringBuilder builder, Iterable<? extends @Nullable Object> parts) {
     return appendTo(builder, parts.iterator());
   }
 
@@ -147,7 +163,8 @@ public final StringBuilder appendTo(StringBuilder builder, Iterable<?> parts) {
    * @since 11.0
    */
   @CanIgnoreReturnValue
-  public final StringBuilder appendTo(StringBuilder builder, Iterator<?> parts) {
+  public final StringBuilder appendTo(
+      StringBuilder builder, Iterator<? extends @Nullable Object> parts) {
     try {
       appendTo((Appendable) builder, parts);
     } catch (IOException impossible) {
@@ -162,7 +179,7 @@ public final StringBuilder appendTo(StringBuilder builder, Iterator<?> parts) {
    * Iterable)}, except that it does not throw {@link IOException}.
    */
   @CanIgnoreReturnValue
-  public final StringBuilder appendTo(StringBuilder builder, Object[] parts) {
+  public final StringBuilder appendTo(StringBuilder builder, @Nullable Object[] parts) {
     return appendTo(builder, Arrays.asList(parts));
   }
 
@@ -174,9 +191,9 @@ public final StringBuilder appendTo(StringBuilder builder, Object[] parts) {
   @CanIgnoreReturnValue
   public final StringBuilder appendTo(
       StringBuilder builder,
-      @NullableDecl Object first,
-      @NullableDecl Object second,
-      Object... rest) {
+      @CheckForNull Object first,
+      @CheckForNull Object second,
+      @Nullable Object... rest) {
     return appendTo(builder, iterable(first, second, rest));
   }
 
@@ -184,7 +201,7 @@ public final StringBuilder appendTo(
    * Returns a string containing the string representation of each of {@code parts}, using the
    * previously configured separator between each.
    */
-  public final String join(Iterable<?> parts) {
+  public final String join(Iterable<? extends @Nullable Object> parts) {
     return join(parts.iterator());
   }
 
@@ -194,7 +211,7 @@ public final String join(Iterable<?> parts) {
    *
    * @since 11.0
    */
-  public final String join(Iterator<?> parts) {
+  public final String join(Iterator<? extends @Nullable Object> parts) {
     return appendTo(new StringBuilder(), parts).toString();
   }
 
@@ -202,7 +219,7 @@ public final String join(Iterator<?> parts) {
    * Returns a string containing the string representation of each of {@code parts}, using the
    * previously configured separator between each.
    */
-  public final String join(Object[] parts) {
+  public final String join(@Nullable Object[] parts) {
     return join(Arrays.asList(parts));
   }
 
@@ -211,7 +228,7 @@ public final String join(Object[] parts) {
    * configured separator between each.
    */
   public final String join(
-      @NullableDecl Object first, @NullableDecl Object second, Object... rest) {
+      @CheckForNull Object first, @CheckForNull Object second, @Nullable Object... rest) {
     return join(iterable(first, second, rest));
   }
 
@@ -219,11 +236,11 @@ public final String join(
    * Returns a joiner with the same behavior as this one, except automatically substituting {@code
    * nullText} for any provided null elements.
    */
-  public Joiner useForNull(final String nullText) {
+  public Joiner useForNull(String nullText) {
     checkNotNull(nullText);
     return new Joiner(this) {
       @Override
-      CharSequence toString(@NullableDecl Object part) {
+      CharSequence toString(@CheckForNull Object part) {
         return (part == null) ? nullText : Joiner.this.toString(part);
       }
 
@@ -246,7 +263,8 @@ public Joiner skipNulls() {
   public Joiner skipNulls() {
     return new Joiner(this) {
       @Override
-      public <A extends Appendable> A appendTo(A appendable, Iterator<?> parts) throws IOException {
+      public <A extends Appendable> A appendTo(
+          A appendable, Iterator<? extends @Nullable Object> parts) throws IOException {
         checkNotNull(appendable, "appendable");
         checkNotNull(parts, "parts");
         while (parts.hasNext()) {
@@ -452,21 +470,39 @@ public MapJoiner useForNull(String nullText) {
     }
   }
 
-  CharSequence toString(Object part) {
-    checkNotNull(part); // checkNotNull for GWT (do not optimize).
+  CharSequence toString(@CheckForNull Object part) {
+    /*
+     * requireNonNull is not safe: Joiner.on(...).join(somethingThatContainsNull) will indeed throw.
+     * However, Joiner.on(...).useForNull(...).join(somethingThatContainsNull) *is* safe -- because
+     * it returns a subclass of Joiner that overrides this method to tolerate null inputs.
+     *
+     * Unfortunately, we don't distinguish between these two cases in our public API: Joiner.on(...)
+     * and Joiner.on(...).useForNull(...) both declare the same return type: plain Joiner. To ensure
+     * that users *can* pass null arguments to Joiner, we annotate it as if it always tolerates null
+     * inputs, rather than as if it never tolerates them.
+     *
+     * We rely on checkers to implement special cases to catch dangerous calls to join(), etc. based
+     * on what they know about the particular Joiner instances the calls are performed on.
+     *
+     * (In addition to useForNull, we also offer skipNulls. It, too, tolerates null inputs, but its
+     * tolerance is implemented differently: Its implementation avoids calling this toString(Object)
+     * method in the first place.)
+     */
+    requireNonNull(part);
     return (part instanceof CharSequence) ? (CharSequence) part : part.toString();
   }
 
-  private static Iterable<Object> iterable(
-      final Object first, final Object second, final Object[] rest) {
+  private static Iterable<@Nullable Object> iterable(
+      @CheckForNull Object first, @CheckForNull Object second, @Nullable Object[] rest) {
     checkNotNull(rest);
-    return new AbstractList<Object>() {
+    return new AbstractList<@Nullable Object>() {
       @Override
       public int size() {
         return rest.length + 2;
       }
 
       @Override
+      @CheckForNull
       public Object get(int index) {
         switch (index) {
           case 0:
diff --git a/android/guava/src/com/google/common/base/MoreObjects.java b/android/guava/src/com/google/common/base/MoreObjects.java
index a56b2a69def0..da976242479b 100644
--- a/android/guava/src/com/google/common/base/MoreObjects.java
+++ b/android/guava/src/com/google/common/base/MoreObjects.java
@@ -18,8 +18,11 @@
 
 import com.google.common.annotations.GwtCompatible;
 import com.google.errorprone.annotations.CanIgnoreReturnValue;
+import java.lang.reflect.Array;
 import java.util.Arrays;
-import org.checkerframework.checker.nullness.compatqual.NullableDecl;
+import java.util.Collection;
+import java.util.Map;
+import javax.annotation.CheckForNull;
 
 /**
  * Helper functions that operate on any {@code Object}, and are not already provided in {@link
@@ -33,6 +36,7 @@
  * @since 18.0 (since 2.0 as {@code Objects})
  */
 @GwtCompatible
+@ElementTypesAreNonnullByDefault
 public final class MoreObjects {
   /**
    * Returns the first of two given parameters that is not {@code null}, if either is, or otherwise
@@ -54,7 +58,24 @@ public final class MoreObjects {
    * @throws NullPointerException if both {@code first} and {@code second} are null
    * @since 18.0 (since 3.0 as {@code Objects.firstNonNull()}).
    */
-  public static <T> T firstNonNull(@NullableDecl T first, @NullableDecl T second) {
+  /*
+   * We annotate firstNonNull in a way that protects against NullPointerException at the cost of
+   * forbidding some reasonable calls.
+   *
+   * The more permissive signature would be to accept (@CheckForNull T first, @CheckForNull T
+   * second), since it's OK for `second` to be null as long as `first` is not also null. But we
+   * expect for that flexibility to be useful relatively rarely: The more common use case is to
+   * supply a clearly non-null default, like `firstNonNull(someString, "")`. And users who really
+   * know that `first` is guaranteed non-null when `second` is null can write the logic out
+   * longhand, including a requireNonNull call, which calls attention to the fact that the static
+   * analyzer can't prove that the operation is safe.
+   *
+   * This matches the signature we currently have for requireNonNullElse in our own checker. (And
+   * that in turn matches that method's signature under the Checker Framework.) As always, we could
+   * consider the more flexible signature if we judge it worth the risks. If we do, we would likely
+   * update both methods so that they continue to match.
+   */
+  public static <T> T firstNonNull(@CheckForNull T first, T second) {
     if (first != null) {
       return first;
     }
@@ -145,6 +166,7 @@ public static final class ToStringHelper {
     private final ValueHolder holderHead = new ValueHolder();
     private ValueHolder holderTail = holderHead;
     private boolean omitNullValues = false;
+    private boolean omitEmptyValues = false;
 
     /** Use {@link MoreObjects#toStringHelper(Object)} to create an instance. */
     private ToStringHelper(String className) {
@@ -170,7 +192,7 @@ public ToStringHelper omitNullValues() {
      * called, in which case this name/value pair will not be added.
      */
     @CanIgnoreReturnValue
-    public ToStringHelper add(String name, @NullableDecl Object value) {
+    public ToStringHelper add(String name, @CheckForNull Object value) {
       return addHolder(name, value);
     }
 
@@ -181,7 +203,7 @@ public ToStringHelper add(String name, @NullableDecl Object value) {
      */
     @CanIgnoreReturnValue
     public ToStringHelper add(String name, boolean value) {
-      return addHolder(name, String.valueOf(value));
+      return addUnconditionalHolder(name, String.valueOf(value));
     }
 
     /**
@@ -191,7 +213,7 @@ public ToStringHelper add(String name, boolean value) {
      */
     @CanIgnoreReturnValue
     public ToStringHelper add(String name, char value) {
-      return addHolder(name, String.valueOf(value));
+      return addUnconditionalHolder(name, String.valueOf(value));
     }
 
     /**
@@ -201,7 +223,7 @@ public ToStringHelper add(String name, char value) {
      */
     @CanIgnoreReturnValue
     public ToStringHelper add(String name, double value) {
-      return addHolder(name, String.valueOf(value));
+      return addUnconditionalHolder(name, String.valueOf(value));
     }
 
     /**
@@ -211,7 +233,7 @@ public ToStringHelper add(String name, double value) {
      */
     @CanIgnoreReturnValue
     public ToStringHelper add(String name, float value) {
-      return addHolder(name, String.valueOf(value));
+      return addUnconditionalHolder(name, String.valueOf(value));
     }
 
     /**
@@ -221,7 +243,7 @@ public ToStringHelper add(String name, float value) {
      */
     @CanIgnoreReturnValue
     public ToStringHelper add(String name, int value) {
-      return addHolder(name, String.valueOf(value));
+      return addUnconditionalHolder(name, String.valueOf(value));
     }
 
     /**
@@ -231,7 +253,7 @@ public ToStringHelper add(String name, int value) {
      */
     @CanIgnoreReturnValue
     public ToStringHelper add(String name, long value) {
-      return addHolder(name, String.valueOf(value));
+      return addUnconditionalHolder(name, String.valueOf(value));
     }
 
     /**
@@ -241,7 +263,7 @@ public ToStringHelper add(String name, long value) {
      * readable name.
      */
     @CanIgnoreReturnValue
-    public ToStringHelper addValue(@NullableDecl Object value) {
+    public ToStringHelper addValue(@CheckForNull Object value) {
       return addHolder(value);
     }
 
@@ -255,7 +277,7 @@ public ToStringHelper addValue(@NullableDecl Object value) {
      */
     @CanIgnoreReturnValue
     public ToStringHelper addValue(boolean value) {
-      return addHolder(String.valueOf(value));
+      return addUnconditionalHolder(String.valueOf(value));
     }
 
     /**
@@ -268,7 +290,7 @@ public ToStringHelper addValue(boolean value) {
      */
     @CanIgnoreReturnValue
     public ToStringHelper addValue(char value) {
-      return addHolder(String.valueOf(value));
+      return addUnconditionalHolder(String.valueOf(value));
     }
 
     /**
@@ -281,7 +303,7 @@ public ToStringHelper addValue(char value) {
      */
     @CanIgnoreReturnValue
     public ToStringHelper addValue(double value) {
-      return addHolder(String.valueOf(value));
+      return addUnconditionalHolder(String.valueOf(value));
     }
 
     /**
@@ -294,7 +316,7 @@ public ToStringHelper addValue(double value) {
      */
     @CanIgnoreReturnValue
     public ToStringHelper addValue(float value) {
-      return addHolder(String.valueOf(value));
+      return addUnconditionalHolder(String.valueOf(value));
     }
 
     /**
@@ -307,7 +329,7 @@ public ToStringHelper addValue(float value) {
      */
     @CanIgnoreReturnValue
     public ToStringHelper addValue(int value) {
-      return addHolder(String.valueOf(value));
+      return addUnconditionalHolder(String.valueOf(value));
     }
 
     /**
@@ -320,7 +342,23 @@ public ToStringHelper addValue(int value) {
      */
     @CanIgnoreReturnValue
     public ToStringHelper addValue(long value) {
-      return addHolder(String.valueOf(value));
+      return addUnconditionalHolder(String.valueOf(value));
+    }
+
+    private static boolean isEmpty(Object value) {
+      // Put types estimated to be most frequent first.
+      if (value instanceof CharSequence) {
+        return ((CharSequence) value).length() == 0;
+      } else if (value instanceof Collection) {
+        return ((Collection<?>) value).isEmpty();
+      } else if (value instanceof Map) {
+        return ((Map<?, ?>) value).isEmpty();
+      } else if (value instanceof Optional) {
+        return !((Optional) value).isPresent();
+      } else if (value.getClass().isArray()) {
+        return Array.getLength(value) == 0;
+      }
+      return false;
     }
 
     /**
@@ -335,13 +373,17 @@ public ToStringHelper addValue(long value) {
     public String toString() {
       // create a copy to keep it consistent in case value changes
       boolean omitNullValuesSnapshot = omitNullValues;
+      boolean omitEmptyValuesSnapshot = omitEmptyValues;
       String nextSeparator = "";
       StringBuilder builder = new StringBuilder(32).append(className).append('{');
       for (ValueHolder valueHolder = holderHead.next;
           valueHolder != null;
           valueHolder = valueHolder.next) {
         Object value = valueHolder.value;
-        if (!omitNullValuesSnapshot || value != null) {
+        if (valueHolder instanceof UnconditionalValueHolder
+            || (value == null
+                ? !omitNullValuesSnapshot
+                : (!omitEmptyValuesSnapshot || !isEmpty(value)))) {
           builder.append(nextSeparator);
           nextSeparator = ", ";
 
@@ -366,24 +408,51 @@ private ValueHolder addHolder() {
       return valueHolder;
     }
 
-    private ToStringHelper addHolder(@NullableDecl Object value) {
+    private ToStringHelper addHolder(@CheckForNull Object value) {
       ValueHolder valueHolder = addHolder();
       valueHolder.value = value;
       return this;
     }
 
-    private ToStringHelper addHolder(String name, @NullableDecl Object value) {
+    private ToStringHelper addHolder(String name, @CheckForNull Object value) {
       ValueHolder valueHolder = addHolder();
       valueHolder.value = value;
       valueHolder.name = checkNotNull(name);
       return this;
     }
 
-    private static final class ValueHolder {
-      @NullableDecl String name;
-      @NullableDecl Object value;
-      @NullableDecl ValueHolder next;
+    private UnconditionalValueHolder addUnconditionalHolder() {
+      UnconditionalValueHolder valueHolder = new UnconditionalValueHolder();
+      holderTail = holderTail.next = valueHolder;
+      return valueHolder;
+    }
+
+    private ToStringHelper addUnconditionalHolder(Object value) {
+      UnconditionalValueHolder valueHolder = addUnconditionalHolder();
+      valueHolder.value = value;
+      return this;
+    }
+
+    private ToStringHelper addUnconditionalHolder(String name, Object value) {
+      UnconditionalValueHolder valueHolder = addUnconditionalHolder();
+      valueHolder.value = value;
+      valueHolder.name = checkNotNull(name);
+      return this;
+    }
+
+    // Holder object for values that might be null and/or empty.
+    private static class ValueHolder {
+      @CheckForNull String name;
+      @CheckForNull Object value;
+      @CheckForNull ValueHolder next;
     }
+
+    /**
+     * Holder object for values that cannot be null or empty (will be printed unconditionally). This
+     * helps to shortcut most calls to isEmpty(), which is important because the check for emptiness
+     * is relatively expensive. Use a subtype so this also doesn't need any extra storage.
+     */
+    private static final class UnconditionalValueHolder extends ValueHolder {}
   }
 
   private MoreObjects() {}
diff --git a/android/guava/src/com/google/common/base/NullnessCasts.java b/android/guava/src/com/google/common/base/NullnessCasts.java
new file mode 100644
index 000000000000..1ada6bf26148
--- /dev/null
+++ b/android/guava/src/com/google/common/base/NullnessCasts.java
@@ -0,0 +1,60 @@
+/*
+ * Copyright (C) 2021 The Guava Authors
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file except
+ * in compliance with the License. You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software distributed under the License
+ * is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express
+ * or implied. See the License for the specific language governing permissions and limitations under
+ * the License.
+ */
+
+package com.google.common.base;
+
+import com.google.common.annotations.GwtCompatible;
+import javax.annotation.CheckForNull;
+import org.checkerframework.checker.nullness.qual.Nullable;
+
+/** A utility method to perform unchecked casts to suppress errors produced by nullness analyses. */
+@GwtCompatible
+@ElementTypesAreNonnullByDefault
+final class NullnessCasts {
+  /**
+   * Accepts a {@code @Nullable T} and returns a plain {@code T}, without performing any check that
+   * that conversion is safe.
+   *
+   * <p>This method is intended to help with usages of type parameters that have {@linkplain
+   * ParametricNullness parametric nullness}. If a type parameter instead ranges over only non-null
+   * types (or if the type is a non-variable type, like {@code String}), then code should almost
+   * never use this method, preferring instead to call {@code requireNonNull} so as to benefit from
+   * its runtime check.
+   *
+   * <p>An example use case for this method is in implementing an {@code Iterator<T>} whose {@code
+   * next} field is lazily initialized. The type of that field would be {@code @Nullable T}, and the
+   * code would be responsible for populating a "real" {@code T} (which might still be the value
+   * {@code null}!) before returning it to callers. Depending on how the code is structured, a
+   * nullness analysis might not understand that the field has been populated. To avoid that problem
+   * without having to add {@code @SuppressWarnings}, the code can call this method.
+   *
+   * <p>Why <i>not</i> just add {@code SuppressWarnings}? The problem is that this method is
+   * typically useful for {@code return} statements. That leaves the code with two options: Either
+   * add the suppression to the whole method (which turns off checking for a large section of code),
+   * or extract a variable, and put the suppression on that. However, a local variable typically
+   * doesn't work: Because nullness analyses typically infer the nullness of local variables,
+   * there's no way to assign a {@code @Nullable T} to a field {@code T foo;} and instruct the
+   * analysis that that means "plain {@code T}" rather than the inferred type {@code @Nullable T}.
+   * (Even if supported added {@code @NonNull}, that would not help, since the problem case
+   * addressed by this method is the case in which {@code T} has parametric nullness -- and thus its
+   * value may be legitimately {@code null}.)
+   */
+  @ParametricNullness
+  @SuppressWarnings("nullness")
+  static <T extends @Nullable Object> T uncheckedCastNullableTToT(@CheckForNull T t) {
+    return t;
+  }
+
+  private NullnessCasts() {}
+}
diff --git a/android/guava/src/com/google/common/base/Objects.java b/android/guava/src/com/google/common/base/Objects.java
index 1a409a68df02..bd6b0d94c5f0 100644
--- a/android/guava/src/com/google/common/base/Objects.java
+++ b/android/guava/src/com/google/common/base/Objects.java
@@ -16,7 +16,8 @@
 
 import com.google.common.annotations.GwtCompatible;
 import java.util.Arrays;
-import org.checkerframework.checker.nullness.compatqual.NullableDecl;
+import javax.annotation.CheckForNull;
+import org.checkerframework.checker.nullness.qual.Nullable;
 
 /**
  * Helper functions that can operate on any {@code Object}.
@@ -29,6 +30,7 @@
  * @since 2.0
  */
 @GwtCompatible
+@ElementTypesAreNonnullByDefault
 public final class Objects extends ExtraObjectsMethodsForWeb {
   private Objects() {}
 
@@ -48,7 +50,7 @@ private Objects() {}
    * <p><b>Note for Java 7 and later:</b> This method should be treated as deprecated; use {@link
    * java.util.Objects#equals} instead.
    */
-  public static boolean equal(@NullableDecl Object a, @NullableDecl Object b) {
+  public static boolean equal(@CheckForNull Object a, @CheckForNull Object b) {
     return a == b || (a != null && a.equals(b));
   }
 
@@ -73,7 +75,7 @@ public static boolean equal(@NullableDecl Object a, @NullableDecl Object b) {
    * <p><b>Note for Java 7 and later:</b> This method should be treated as deprecated; use {@link
    * java.util.Objects#hash} instead.
    */
-  public static int hashCode(@NullableDecl Object... objects) {
+  public static int hashCode(@CheckForNull @Nullable Object... objects) {
     return Arrays.hashCode(objects);
   }
 }
diff --git a/android/guava/src/com/google/common/base/Optional.java b/android/guava/src/com/google/common/base/Optional.java
index 611ba54942b0..a7a0b3d72038 100644
--- a/android/guava/src/com/google/common/base/Optional.java
+++ b/android/guava/src/com/google/common/base/Optional.java
@@ -22,7 +22,7 @@
 import java.io.Serializable;
 import java.util.Iterator;
 import java.util.Set;
-import org.checkerframework.checker.nullness.compatqual.NullableDecl;
+import javax.annotation.CheckForNull;
 
 /**
  * An immutable object that may contain a non-null reference to another object. Each instance of
@@ -82,6 +82,7 @@
  */
 @DoNotMock("Use Optional.of(value) or Optional.absent()")
 @GwtCompatible(serializable = true)
+@ElementTypesAreNonnullByDefault
 public abstract class Optional<T> implements Serializable {
   /**
    * Returns an {@code Optional} instance with no contained reference.
@@ -112,7 +113,7 @@ public static <T> Optional<T> of(T reference) {
    * <p><b>Comparison to {@code java.util.Optional}:</b> this method is equivalent to Java 8's
    * {@code Optional.ofNullable}.
    */
-  public static <T> Optional<T> fromNullable(@NullableDecl T nullableReference) {
+  public static <T> Optional<T> fromNullable(@CheckForNull T nullableReference) {
     return (nullableReference == null) ? Optional.<T>absent() : new Present<T>(nullableReference);
   }
 
@@ -206,7 +207,7 @@ public static <T> Optional<T> fromNullable(@NullableDecl T nullableReference) {
    * <p><b>Comparison to {@code java.util.Optional}:</b> this method is equivalent to Java 8's
    * {@code Optional.orElse(null)}.
    */
-  @NullableDecl
+  @CheckForNull
   public abstract T orNull();
 
   /**
@@ -255,7 +256,7 @@ public static <T> Optional<T> fromNullable(@NullableDecl T nullableReference) {
    * <p><b>Comparison to {@code java.util.Optional}:</b> no differences.
    */
   @Override
-  public abstract boolean equals(@NullableDecl Object object);
+  public abstract boolean equals(@CheckForNull Object object);
 
   /**
    * Returns a hash code for this instance.
@@ -300,6 +301,7 @@ public Iterator<T> iterator() {
               checkNotNull(optionals.iterator());
 
           @Override
+          @CheckForNull
           protected T computeNext() {
             while (iterator.hasNext()) {
               Optional<? extends T> optional = iterator.next();
diff --git a/android/guava/src/com/google/common/base/PairwiseEquivalence.java b/android/guava/src/com/google/common/base/PairwiseEquivalence.java
index cb7d784f016c..74be27fd7c6f 100644
--- a/android/guava/src/com/google/common/base/PairwiseEquivalence.java
+++ b/android/guava/src/com/google/common/base/PairwiseEquivalence.java
@@ -17,14 +17,16 @@
 import com.google.common.annotations.GwtCompatible;
 import java.io.Serializable;
 import java.util.Iterator;
-import org.checkerframework.checker.nullness.compatqual.NullableDecl;
+import javax.annotation.CheckForNull;
+import org.checkerframework.checker.nullness.qual.Nullable;
 
 @GwtCompatible(serializable = true)
-final class PairwiseEquivalence<T> extends Equivalence<Iterable<T>> implements Serializable {
+@ElementTypesAreNonnullByDefault
+final class PairwiseEquivalence<E, T extends @Nullable E> extends Equivalence<Iterable<T>>
+    implements Serializable {
+  final Equivalence<E> elementEquivalence;
 
-  final Equivalence<? super T> elementEquivalence;
-
-  PairwiseEquivalence(Equivalence<? super T> elementEquivalence) {
+  PairwiseEquivalence(Equivalence<E> elementEquivalence) {
     this.elementEquivalence = Preconditions.checkNotNull(elementEquivalence);
   }
 
@@ -52,9 +54,9 @@ protected int doHash(Iterable<T> iterable) {
   }
 
   @Override
-  public boolean equals(@NullableDecl Object object) {
+  public boolean equals(@CheckForNull Object object) {
     if (object instanceof PairwiseEquivalence) {
-      PairwiseEquivalence<?> that = (PairwiseEquivalence<?>) object;
+      PairwiseEquivalence<?, ?> that = (PairwiseEquivalence<?, ?>) object;
       return this.elementEquivalence.equals(that.elementEquivalence);
     }
 
diff --git a/android/guava/src/com/google/common/base/ParametricNullness.java b/android/guava/src/com/google/common/base/ParametricNullness.java
new file mode 100644
index 000000000000..5b595adb3ffb
--- /dev/null
+++ b/android/guava/src/com/google/common/base/ParametricNullness.java
@@ -0,0 +1,52 @@
+/*
+ * Copyright (C) 2021 The Guava Authors
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package com.google.common.base;
+
+import static java.lang.annotation.ElementType.FIELD;
+import static java.lang.annotation.ElementType.METHOD;
+import static java.lang.annotation.ElementType.PARAMETER;
+import static java.lang.annotation.RetentionPolicy.RUNTIME;
+
+import com.google.common.annotations.GwtCompatible;
+import java.lang.annotation.Retention;
+import java.lang.annotation.Target;
+
+/**
+ * Marks a "top-level" type-variable usage as the closest we can get to "non-nullable when
+ * non-nullable; nullable when nullable" (like the Android <a
+ * href="https://android.googlesource.com/platform/libcore/+/master/luni/src/main/java/libcore/util/NullFromTypeParam.java">{@code
+ * NullFromTypeParam}</a>).
+ *
+ * <p>Consumers of this annotation include:
+ *
+ * <ul>
+ *   <li>Kotlin, for which it makes the type-variable usage (a) a Kotlin platform type when the type
+ *       argument is non-nullable and (b) nullable when the type argument is nullable. We use this
+ *       to "undo" {@link ElementTypesAreNonnullByDefault}.
+ *   <li><a href="https://developers.google.com/j2objc">J2ObjC</a>
+ *   <li>{@code NullPointerTester}, at least in the Android backport (where the type-use annotations
+ *       {@code NullPointerTester} would need are not available) and in case of <a
+ *       href="https://bugs.openjdk.java.net/browse/JDK-8202469">JDK-8202469</a>
+ * </ul>
+ *
+ */
+@GwtCompatible
+@Retention(RUNTIME)
+@Target({FIELD, METHOD, PARAMETER})
+@javax.annotation.meta.TypeQualifierNickname
+@javax.annotation.Nonnull(when = javax.annotation.meta.When.UNKNOWN)
+@interface ParametricNullness {}
diff --git a/android/guava/src/com/google/common/base/PatternCompiler.java b/android/guava/src/com/google/common/base/PatternCompiler.java
index 813a25f65b86..72a45faae963 100644
--- a/android/guava/src/com/google/common/base/PatternCompiler.java
+++ b/android/guava/src/com/google/common/base/PatternCompiler.java
@@ -22,6 +22,7 @@
  * java.util.ServiceLoader} mechanism.
  */
 @GwtIncompatible
+@ElementTypesAreNonnullByDefault
 interface PatternCompiler {
   /**
    * Compiles the given pattern.
diff --git a/android/guava/src/com/google/common/base/Platform.java b/android/guava/src/com/google/common/base/Platform.java
index 896e9db83033..703b8605b1d5 100644
--- a/android/guava/src/com/google/common/base/Platform.java
+++ b/android/guava/src/com/google/common/base/Platform.java
@@ -21,7 +21,7 @@
 import java.util.logging.Level;
 import java.util.logging.Logger;
 import java.util.regex.Pattern;
-import org.checkerframework.checker.nullness.compatqual.NullableDecl;
+import javax.annotation.CheckForNull;
 
 /**
  * Methods factored out so that they can be emulated differently in GWT.
@@ -29,6 +29,7 @@
  * @author Jesse Wilson
  */
 @GwtCompatible(emulated = true)
+@ElementTypesAreNonnullByDefault
 final class Platform {
   private static final Logger logger = Logger.getLogger(Platform.class.getName());
   private static final PatternCompiler patternCompiler = loadPatternCompiler();
@@ -54,7 +55,7 @@ static String formatCompact4Digits(double value) {
     return String.format(Locale.ROOT, "%.4g", value);
   }
 
-  static boolean stringIsNullOrEmpty(@NullableDecl String string) {
+  static boolean stringIsNullOrEmpty(@CheckForNull String string) {
     return string == null || string.isEmpty();
   }
 
@@ -64,7 +65,7 @@ static boolean stringIsNullOrEmpty(@NullableDecl String string) {
    * @param string the string to test and possibly return
    * @return {@code string} if it is not null; {@code ""} otherwise
    */
-  static String nullToEmpty(@NullableDecl String string) {
+  static String nullToEmpty(@CheckForNull String string) {
     return (string == null) ? "" : string;
   }
 
@@ -74,7 +75,8 @@ static String nullToEmpty(@NullableDecl String string) {
    * @param string the string to test and possibly return
    * @return {@code string} if it is not empty; {@code null} otherwise
    */
-  static String emptyToNull(@NullableDecl String string) {
+  @CheckForNull
+  static String emptyToNull(@CheckForNull String string) {
     return stringIsNullOrEmpty(string) ? null : string;
   }
 
diff --git a/android/guava/src/com/google/common/base/Preconditions.java b/android/guava/src/com/google/common/base/Preconditions.java
index 38f665463f7a..13ff77b7f78d 100644
--- a/android/guava/src/com/google/common/base/Preconditions.java
+++ b/android/guava/src/com/google/common/base/Preconditions.java
@@ -15,13 +15,11 @@
 package com.google.common.base;
 
 import static com.google.common.base.Strings.lenientFormat;
-import static java.util.logging.Level.WARNING;
 
 import com.google.common.annotations.GwtCompatible;
 import com.google.errorprone.annotations.CanIgnoreReturnValue;
-import java.util.logging.Logger;
-import org.checkerframework.checker.nullness.compatqual.NonNullDecl;
-import org.checkerframework.checker.nullness.compatqual.NullableDecl;
+import javax.annotation.CheckForNull;
+import org.checkerframework.checker.nullness.qual.Nullable;
 
 /**
  * Static convenience methods that help a method or constructor check whether it was invoked
@@ -116,9 +114,12 @@
  * @since 2.0
  */
 @GwtCompatible
+@ElementTypesAreNonnullByDefault
 public final class Preconditions {
   private Preconditions() {}
 
+  // TODO(cpovirk): Standardize parameter names (expression vs. b, reference vs. obj).
+
   /**
    * Ensures the truth of an expression involving one or more parameters to the calling method.
    *
@@ -139,7 +140,7 @@ public static void checkArgument(boolean expression) {
    *     string using {@link String#valueOf(Object)}
    * @throws IllegalArgumentException if {@code expression} is false
    */
-  public static void checkArgument(boolean expression, @NullableDecl Object errorMessage) {
+  public static void checkArgument(boolean expression, @CheckForNull Object errorMessage) {
     if (!expression) {
       throw new IllegalArgumentException(String.valueOf(errorMessage));
     }
@@ -160,8 +161,8 @@ public static void checkArgument(boolean expression, @NullableDecl Object errorM
    */
   public static void checkArgument(
       boolean expression,
-      @NullableDecl String errorMessageTemplate,
-      @NullableDecl Object... errorMessageArgs) {
+      String errorMessageTemplate,
+      @CheckForNull @Nullable Object... errorMessageArgs) {
     if (!expression) {
       throw new IllegalArgumentException(lenientFormat(errorMessageTemplate, errorMessageArgs));
     }
@@ -174,7 +175,7 @@ public static void checkArgument(
    *
    * @since 20.0 (varargs overload since 2.0)
    */
-  public static void checkArgument(boolean b, @NullableDecl String errorMessageTemplate, char p1) {
+  public static void checkArgument(boolean b, String errorMessageTemplate, char p1) {
     if (!b) {
       throw new IllegalArgumentException(lenientFormat(errorMessageTemplate, p1));
     }
@@ -187,7 +188,7 @@ public static void checkArgument(boolean b, @NullableDecl String errorMessageTem
    *
    * @since 20.0 (varargs overload since 2.0)
    */
-  public static void checkArgument(boolean b, @NullableDecl String errorMessageTemplate, int p1) {
+  public static void checkArgument(boolean b, String errorMessageTemplate, int p1) {
     if (!b) {
       throw new IllegalArgumentException(lenientFormat(errorMessageTemplate, p1));
     }
@@ -200,7 +201,7 @@ public static void checkArgument(boolean b, @NullableDecl String errorMessageTem
    *
    * @since 20.0 (varargs overload since 2.0)
    */
-  public static void checkArgument(boolean b, @NullableDecl String errorMessageTemplate, long p1) {
+  public static void checkArgument(boolean b, String errorMessageTemplate, long p1) {
     if (!b) {
       throw new IllegalArgumentException(lenientFormat(errorMessageTemplate, p1));
     }
@@ -214,7 +215,7 @@ public static void checkArgument(boolean b, @NullableDecl String errorMessageTem
    * @since 20.0 (varargs overload since 2.0)
    */
   public static void checkArgument(
-      boolean b, @NullableDecl String errorMessageTemplate, @NullableDecl Object p1) {
+      boolean b, String errorMessageTemplate, @CheckForNull Object p1) {
     if (!b) {
       throw new IllegalArgumentException(lenientFormat(errorMessageTemplate, p1));
     }
@@ -227,8 +228,7 @@ public static void checkArgument(
    *
    * @since 20.0 (varargs overload since 2.0)
    */
-  public static void checkArgument(
-      boolean b, @NullableDecl String errorMessageTemplate, char p1, char p2) {
+  public static void checkArgument(boolean b, String errorMessageTemplate, char p1, char p2) {
     if (!b) {
       throw new IllegalArgumentException(lenientFormat(errorMessageTemplate, p1, p2));
     }
@@ -241,8 +241,7 @@ public static void checkArgument(
    *
    * @since 20.0 (varargs overload since 2.0)
    */
-  public static void checkArgument(
-      boolean b, @NullableDecl String errorMessageTemplate, char p1, int p2) {
+  public static void checkArgument(boolean b, String errorMessageTemplate, char p1, int p2) {
     if (!b) {
       throw new IllegalArgumentException(lenientFormat(errorMessageTemplate, p1, p2));
     }
@@ -255,8 +254,7 @@ public static void checkArgument(
    *
    * @since 20.0 (varargs overload since 2.0)
    */
-  public static void checkArgument(
-      boolean b, @NullableDecl String errorMessageTemplate, char p1, long p2) {
+  public static void checkArgument(boolean b, String errorMessageTemplate, char p1, long p2) {
     if (!b) {
       throw new IllegalArgumentException(lenientFormat(errorMessageTemplate, p1, p2));
     }
@@ -270,7 +268,7 @@ public static void checkArgument(
    * @since 20.0 (varargs overload since 2.0)
    */
   public static void checkArgument(
-      boolean b, @NullableDecl String errorMessageTemplate, char p1, @NullableDecl Object p2) {
+      boolean b, String errorMessageTemplate, char p1, @CheckForNull Object p2) {
     if (!b) {
       throw new IllegalArgumentException(lenientFormat(errorMessageTemplate, p1, p2));
     }
@@ -283,8 +281,7 @@ public static void checkArgument(
    *
    * @since 20.0 (varargs overload since 2.0)
    */
-  public static void checkArgument(
-      boolean b, @NullableDecl String errorMessageTemplate, int p1, char p2) {
+  public static void checkArgument(boolean b, String errorMessageTemplate, int p1, char p2) {
     if (!b) {
       throw new IllegalArgumentException(lenientFormat(errorMessageTemplate, p1, p2));
     }
@@ -297,8 +294,7 @@ public static void checkArgument(
    *
    * @since 20.0 (varargs overload since 2.0)
    */
-  public static void checkArgument(
-      boolean b, @NullableDecl String errorMessageTemplate, int p1, int p2) {
+  public static void checkArgument(boolean b, String errorMessageTemplate, int p1, int p2) {
     if (!b) {
       throw new IllegalArgumentException(lenientFormat(errorMessageTemplate, p1, p2));
     }
@@ -311,8 +307,7 @@ public static void checkArgument(
    *
    * @since 20.0 (varargs overload since 2.0)
    */
-  public static void checkArgument(
-      boolean b, @NullableDecl String errorMessageTemplate, int p1, long p2) {
+  public static void checkArgument(boolean b, String errorMessageTemplate, int p1, long p2) {
     if (!b) {
       throw new IllegalArgumentException(lenientFormat(errorMessageTemplate, p1, p2));
     }
@@ -326,7 +321,7 @@ public static void checkArgument(
    * @since 20.0 (varargs overload since 2.0)
    */
   public static void checkArgument(
-      boolean b, @NullableDecl String errorMessageTemplate, int p1, @NullableDecl Object p2) {
+      boolean b, String errorMessageTemplate, int p1, @CheckForNull Object p2) {
     if (!b) {
       throw new IllegalArgumentException(lenientFormat(errorMessageTemplate, p1, p2));
     }
@@ -339,8 +334,7 @@ public static void checkArgument(
    *
    * @since 20.0 (varargs overload since 2.0)
    */
-  public static void checkArgument(
-      boolean b, @NullableDecl String errorMessageTemplate, long p1, char p2) {
+  public static void checkArgument(boolean b, String errorMessageTemplate, long p1, char p2) {
     if (!b) {
       throw new IllegalArgumentException(lenientFormat(errorMessageTemplate, p1, p2));
     }
@@ -353,8 +347,7 @@ public static void checkArgument(
    *
    * @since 20.0 (varargs overload since 2.0)
    */
-  public static void checkArgument(
-      boolean b, @NullableDecl String errorMessageTemplate, long p1, int p2) {
+  public static void checkArgument(boolean b, String errorMessageTemplate, long p1, int p2) {
     if (!b) {
       throw new IllegalArgumentException(lenientFormat(errorMessageTemplate, p1, p2));
     }
@@ -367,8 +360,7 @@ public static void checkArgument(
    *
    * @since 20.0 (varargs overload since 2.0)
    */
-  public static void checkArgument(
-      boolean b, @NullableDecl String errorMessageTemplate, long p1, long p2) {
+  public static void checkArgument(boolean b, String errorMessageTemplate, long p1, long p2) {
     if (!b) {
       throw new IllegalArgumentException(lenientFormat(errorMessageTemplate, p1, p2));
     }
@@ -382,7 +374,7 @@ public static void checkArgument(
    * @since 20.0 (varargs overload since 2.0)
    */
   public static void checkArgument(
-      boolean b, @NullableDecl String errorMessageTemplate, long p1, @NullableDecl Object p2) {
+      boolean b, String errorMessageTemplate, long p1, @CheckForNull Object p2) {
     if (!b) {
       throw new IllegalArgumentException(lenientFormat(errorMessageTemplate, p1, p2));
     }
@@ -396,7 +388,7 @@ public static void checkArgument(
    * @since 20.0 (varargs overload since 2.0)
    */
   public static void checkArgument(
-      boolean b, @NullableDecl String errorMessageTemplate, @NullableDecl Object p1, char p2) {
+      boolean b, String errorMessageTemplate, @CheckForNull Object p1, char p2) {
     if (!b) {
       throw new IllegalArgumentException(lenientFormat(errorMessageTemplate, p1, p2));
     }
@@ -410,7 +402,7 @@ public static void checkArgument(
    * @since 20.0 (varargs overload since 2.0)
    */
   public static void checkArgument(
-      boolean b, @NullableDecl String errorMessageTemplate, @NullableDecl Object p1, int p2) {
+      boolean b, String errorMessageTemplate, @CheckForNull Object p1, int p2) {
     if (!b) {
       throw new IllegalArgumentException(lenientFormat(errorMessageTemplate, p1, p2));
     }
@@ -424,7 +416,7 @@ public static void checkArgument(
    * @since 20.0 (varargs overload since 2.0)
    */
   public static void checkArgument(
-      boolean b, @NullableDecl String errorMessageTemplate, @NullableDecl Object p1, long p2) {
+      boolean b, String errorMessageTemplate, @CheckForNull Object p1, long p2) {
     if (!b) {
       throw new IllegalArgumentException(lenientFormat(errorMessageTemplate, p1, p2));
     }
@@ -438,10 +430,7 @@ public static void checkArgument(
    * @since 20.0 (varargs overload since 2.0)
    */
   public static void checkArgument(
-      boolean b,
-      @NullableDecl String errorMessageTemplate,
-      @NullableDecl Object p1,
-      @NullableDecl Object p2) {
+      boolean b, String errorMessageTemplate, @CheckForNull Object p1, @CheckForNull Object p2) {
     if (!b) {
       throw new IllegalArgumentException(lenientFormat(errorMessageTemplate, p1, p2));
     }
@@ -456,10 +445,10 @@ public static void checkArgument(
    */
   public static void checkArgument(
       boolean b,
-      @NullableDecl String errorMessageTemplate,
-      @NullableDecl Object p1,
-      @NullableDecl Object p2,
-      @NullableDecl Object p3) {
+      String errorMessageTemplate,
+      @CheckForNull Object p1,
+      @CheckForNull Object p2,
+      @CheckForNull Object p3) {
     if (!b) {
       throw new IllegalArgumentException(lenientFormat(errorMessageTemplate, p1, p2, p3));
     }
@@ -474,11 +463,11 @@ public static void checkArgument(
    */
   public static void checkArgument(
       boolean b,
-      @NullableDecl String errorMessageTemplate,
-      @NullableDecl Object p1,
-      @NullableDecl Object p2,
-      @NullableDecl Object p3,
-      @NullableDecl Object p4) {
+      String errorMessageTemplate,
+      @CheckForNull Object p1,
+      @CheckForNull Object p2,
+      @CheckForNull Object p3,
+      @CheckForNull Object p4) {
     if (!b) {
       throw new IllegalArgumentException(lenientFormat(errorMessageTemplate, p1, p2, p3, p4));
     }
@@ -508,7 +497,7 @@ public static void checkState(boolean expression) {
    * @throws IllegalStateException if {@code expression} is false
    * @see Verify#verify Verify.verify()
    */
-  public static void checkState(boolean expression, @NullableDecl Object errorMessage) {
+  public static void checkState(boolean expression, @CheckForNull Object errorMessage) {
     if (!expression) {
       throw new IllegalStateException(String.valueOf(errorMessage));
     }
@@ -531,8 +520,16 @@ public static void checkState(boolean expression, @NullableDecl Object errorMess
    */
   public static void checkState(
       boolean expression,
-      @NullableDecl String errorMessageTemplate,
-      @NullableDecl Object... errorMessageArgs) {
+      /*
+       * TODO(cpovirk): Consider removing @CheckForNull here, as we've done with the other methods'
+       * errorMessageTemplate parameters: It it unlikely that callers intend for their string
+       * template to be null (though we do handle that case gracefully at runtime). I've left this
+       * one as it is because one of our users has defined a wrapper API around Preconditions,
+       * declaring a checkState method that accepts a possibly null template. So we'd need to update
+       * that user first.
+       */
+      @CheckForNull String errorMessageTemplate,
+      @CheckForNull @Nullable Object... errorMessageArgs) {
     if (!expression) {
       throw new IllegalStateException(lenientFormat(errorMessageTemplate, errorMessageArgs));
     }
@@ -546,7 +543,7 @@ public static void checkState(
    *
    * @since 20.0 (varargs overload since 2.0)
    */
-  public static void checkState(boolean b, @NullableDecl String errorMessageTemplate, char p1) {
+  public static void checkState(boolean b, String errorMessageTemplate, char p1) {
     if (!b) {
       throw new IllegalStateException(lenientFormat(errorMessageTemplate, p1));
     }
@@ -560,7 +557,7 @@ public static void checkState(boolean b, @NullableDecl String errorMessageTempla
    *
    * @since 20.0 (varargs overload since 2.0)
    */
-  public static void checkState(boolean b, @NullableDecl String errorMessageTemplate, int p1) {
+  public static void checkState(boolean b, String errorMessageTemplate, int p1) {
     if (!b) {
       throw new IllegalStateException(lenientFormat(errorMessageTemplate, p1));
     }
@@ -574,7 +571,7 @@ public static void checkState(boolean b, @NullableDecl String errorMessageTempla
    *
    * @since 20.0 (varargs overload since 2.0)
    */
-  public static void checkState(boolean b, @NullableDecl String errorMessageTemplate, long p1) {
+  public static void checkState(boolean b, String errorMessageTemplate, long p1) {
     if (!b) {
       throw new IllegalStateException(lenientFormat(errorMessageTemplate, p1));
     }
@@ -588,8 +585,7 @@ public static void checkState(boolean b, @NullableDecl String errorMessageTempla
    *
    * @since 20.0 (varargs overload since 2.0)
    */
-  public static void checkState(
-      boolean b, @NullableDecl String errorMessageTemplate, @NullableDecl Object p1) {
+  public static void checkState(boolean b, String errorMessageTemplate, @CheckForNull Object p1) {
     if (!b) {
       throw new IllegalStateException(lenientFormat(errorMessageTemplate, p1));
     }
@@ -603,8 +599,7 @@ public static void checkState(
    *
    * @since 20.0 (varargs overload since 2.0)
    */
-  public static void checkState(
-      boolean b, @NullableDecl String errorMessageTemplate, char p1, char p2) {
+  public static void checkState(boolean b, String errorMessageTemplate, char p1, char p2) {
     if (!b) {
       throw new IllegalStateException(lenientFormat(errorMessageTemplate, p1, p2));
     }
@@ -618,8 +613,7 @@ public static void checkState(
    *
    * @since 20.0 (varargs overload since 2.0)
    */
-  public static void checkState(
-      boolean b, @NullableDecl String errorMessageTemplate, char p1, int p2) {
+  public static void checkState(boolean b, String errorMessageTemplate, char p1, int p2) {
     if (!b) {
       throw new IllegalStateException(lenientFormat(errorMessageTemplate, p1, p2));
     }
@@ -633,8 +627,7 @@ public static void checkState(
    *
    * @since 20.0 (varargs overload since 2.0)
    */
-  public static void checkState(
-      boolean b, @NullableDecl String errorMessageTemplate, char p1, long p2) {
+  public static void checkState(boolean b, String errorMessageTemplate, char p1, long p2) {
     if (!b) {
       throw new IllegalStateException(lenientFormat(errorMessageTemplate, p1, p2));
     }
@@ -649,7 +642,7 @@ public static void checkState(
    * @since 20.0 (varargs overload since 2.0)
    */
   public static void checkState(
-      boolean b, @NullableDecl String errorMessageTemplate, char p1, @NullableDecl Object p2) {
+      boolean b, String errorMessageTemplate, char p1, @CheckForNull Object p2) {
     if (!b) {
       throw new IllegalStateException(lenientFormat(errorMessageTemplate, p1, p2));
     }
@@ -663,8 +656,7 @@ public static void checkState(
    *
    * @since 20.0 (varargs overload since 2.0)
    */
-  public static void checkState(
-      boolean b, @NullableDecl String errorMessageTemplate, int p1, char p2) {
+  public static void checkState(boolean b, String errorMessageTemplate, int p1, char p2) {
     if (!b) {
       throw new IllegalStateException(lenientFormat(errorMessageTemplate, p1, p2));
     }
@@ -678,8 +670,7 @@ public static void checkState(
    *
    * @since 20.0 (varargs overload since 2.0)
    */
-  public static void checkState(
-      boolean b, @NullableDecl String errorMessageTemplate, int p1, int p2) {
+  public static void checkState(boolean b, String errorMessageTemplate, int p1, int p2) {
     if (!b) {
       throw new IllegalStateException(lenientFormat(errorMessageTemplate, p1, p2));
     }
@@ -693,8 +684,7 @@ public static void checkState(
    *
    * @since 20.0 (varargs overload since 2.0)
    */
-  public static void checkState(
-      boolean b, @NullableDecl String errorMessageTemplate, int p1, long p2) {
+  public static void checkState(boolean b, String errorMessageTemplate, int p1, long p2) {
     if (!b) {
       throw new IllegalStateException(lenientFormat(errorMessageTemplate, p1, p2));
     }
@@ -709,7 +699,7 @@ public static void checkState(
    * @since 20.0 (varargs overload since 2.0)
    */
   public static void checkState(
-      boolean b, @NullableDecl String errorMessageTemplate, int p1, @NullableDecl Object p2) {
+      boolean b, String errorMessageTemplate, int p1, @CheckForNull Object p2) {
     if (!b) {
       throw new IllegalStateException(lenientFormat(errorMessageTemplate, p1, p2));
     }
@@ -723,8 +713,7 @@ public static void checkState(
    *
    * @since 20.0 (varargs overload since 2.0)
    */
-  public static void checkState(
-      boolean b, @NullableDecl String errorMessageTemplate, long p1, char p2) {
+  public static void checkState(boolean b, String errorMessageTemplate, long p1, char p2) {
     if (!b) {
       throw new IllegalStateException(lenientFormat(errorMessageTemplate, p1, p2));
     }
@@ -738,8 +727,7 @@ public static void checkState(
    *
    * @since 20.0 (varargs overload since 2.0)
    */
-  public static void checkState(
-      boolean b, @NullableDecl String errorMessageTemplate, long p1, int p2) {
+  public static void checkState(boolean b, String errorMessageTemplate, long p1, int p2) {
     if (!b) {
       throw new IllegalStateException(lenientFormat(errorMessageTemplate, p1, p2));
     }
@@ -753,8 +741,7 @@ public static void checkState(
    *
    * @since 20.0 (varargs overload since 2.0)
    */
-  public static void checkState(
-      boolean b, @NullableDecl String errorMessageTemplate, long p1, long p2) {
+  public static void checkState(boolean b, String errorMessageTemplate, long p1, long p2) {
     if (!b) {
       throw new IllegalStateException(lenientFormat(errorMessageTemplate, p1, p2));
     }
@@ -769,7 +756,7 @@ public static void checkState(
    * @since 20.0 (varargs overload since 2.0)
    */
   public static void checkState(
-      boolean b, @NullableDecl String errorMessageTemplate, long p1, @NullableDecl Object p2) {
+      boolean b, String errorMessageTemplate, long p1, @CheckForNull Object p2) {
     if (!b) {
       throw new IllegalStateException(lenientFormat(errorMessageTemplate, p1, p2));
     }
@@ -784,7 +771,7 @@ public static void checkState(
    * @since 20.0 (varargs overload since 2.0)
    */
   public static void checkState(
-      boolean b, @NullableDecl String errorMessageTemplate, @NullableDecl Object p1, char p2) {
+      boolean b, String errorMessageTemplate, @CheckForNull Object p1, char p2) {
     if (!b) {
       throw new IllegalStateException(lenientFormat(errorMessageTemplate, p1, p2));
     }
@@ -799,7 +786,7 @@ public static void checkState(
    * @since 20.0 (varargs overload since 2.0)
    */
   public static void checkState(
-      boolean b, @NullableDecl String errorMessageTemplate, @NullableDecl Object p1, int p2) {
+      boolean b, String errorMessageTemplate, @CheckForNull Object p1, int p2) {
     if (!b) {
       throw new IllegalStateException(lenientFormat(errorMessageTemplate, p1, p2));
     }
@@ -814,7 +801,7 @@ public static void checkState(
    * @since 20.0 (varargs overload since 2.0)
    */
   public static void checkState(
-      boolean b, @NullableDecl String errorMessageTemplate, @NullableDecl Object p1, long p2) {
+      boolean b, String errorMessageTemplate, @CheckForNull Object p1, long p2) {
     if (!b) {
       throw new IllegalStateException(lenientFormat(errorMessageTemplate, p1, p2));
     }
@@ -829,10 +816,7 @@ public static void checkState(
    * @since 20.0 (varargs overload since 2.0)
    */
   public static void checkState(
-      boolean b,
-      @NullableDecl String errorMessageTemplate,
-      @NullableDecl Object p1,
-      @NullableDecl Object p2) {
+      boolean b, String errorMessageTemplate, @CheckForNull Object p1, @CheckForNull Object p2) {
     if (!b) {
       throw new IllegalStateException(lenientFormat(errorMessageTemplate, p1, p2));
     }
@@ -848,10 +832,10 @@ public static void checkState(
    */
   public static void checkState(
       boolean b,
-      @NullableDecl String errorMessageTemplate,
-      @NullableDecl Object p1,
-      @NullableDecl Object p2,
-      @NullableDecl Object p3) {
+      String errorMessageTemplate,
+      @CheckForNull Object p1,
+      @CheckForNull Object p2,
+      @CheckForNull Object p3) {
     if (!b) {
       throw new IllegalStateException(lenientFormat(errorMessageTemplate, p1, p2, p3));
     }
@@ -867,16 +851,30 @@ public static void checkState(
    */
   public static void checkState(
       boolean b,
-      @NullableDecl String errorMessageTemplate,
-      @NullableDecl Object p1,
-      @NullableDecl Object p2,
-      @NullableDecl Object p3,
-      @NullableDecl Object p4) {
+      String errorMessageTemplate,
+      @CheckForNull Object p1,
+      @CheckForNull Object p2,
+      @CheckForNull Object p3,
+      @CheckForNull Object p4) {
     if (!b) {
       throw new IllegalStateException(lenientFormat(errorMessageTemplate, p1, p2, p3, p4));
     }
   }
 
+  /*
+   * Preconditions.checkNotNull is *intended* for performing eager null checks on parameters that a
+   * nullness checker can already "prove" are non-null. That means that the first parameter to
+   * checkNotNull *should* be annotated to require it to be non-null.
+   *
+   * However, for a variety of reasons, Google developers have written a ton of code over the past
+   * decade that assumes that they can use checkNotNull for non-precondition checks. I had hoped to
+   * take a principled stand on this, but the amount of such code is simply overwhelming. To avoid
+   * creating a lot of compile errors that users would not find to be informative, we're giving in
+   * and allowing callers to pass arguments that a nullness checker believes could be null.
+   *
+   * We still encourage people to use requireNonNull over checkNotNull for non-precondition checks.
+   */
+
   /**
    * Ensures that an object reference passed as a parameter to the calling method is not null.
    *
@@ -886,8 +884,7 @@ public static void checkState(
    * @see Verify#verifyNotNull Verify.verifyNotNull()
    */
   @CanIgnoreReturnValue
-  @NonNullDecl
-  public static <T extends Object> T checkNotNull(@NonNullDecl T reference) {
+  public static <T> T checkNotNull(@CheckForNull T reference) {
     if (reference == null) {
       throw new NullPointerException();
     }
@@ -905,9 +902,7 @@ public static <T extends Object> T checkNotNull(@NonNullDecl T reference) {
    * @see Verify#verifyNotNull Verify.verifyNotNull()
    */
   @CanIgnoreReturnValue
-  @NonNullDecl
-  public static <T extends Object> T checkNotNull(
-      @NonNullDecl T reference, @NullableDecl Object errorMessage) {
+  public static <T> T checkNotNull(@CheckForNull T reference, @CheckForNull Object errorMessage) {
     if (reference == null) {
       throw new NullPointerException(String.valueOf(errorMessage));
     }
@@ -930,11 +925,10 @@ public static <T extends Object> T checkNotNull(
    * @see Verify#verifyNotNull Verify.verifyNotNull()
    */
   @CanIgnoreReturnValue
-  @NonNullDecl
-  public static <T extends Object> T checkNotNull(
-      @NonNullDecl T reference,
-      @NullableDecl String errorMessageTemplate,
-      @NullableDecl Object... errorMessageArgs) {
+  public static <T> T checkNotNull(
+      @CheckForNull T reference,
+      String errorMessageTemplate,
+      @CheckForNull @Nullable Object... errorMessageArgs) {
     if (reference == null) {
       throw new NullPointerException(lenientFormat(errorMessageTemplate, errorMessageArgs));
     }
@@ -949,9 +943,7 @@ public static <T extends Object> T checkNotNull(
    * @since 20.0 (varargs overload since 2.0)
    */
   @CanIgnoreReturnValue
-  @NonNullDecl
-  public static <T extends Object> T checkNotNull(
-      @NonNullDecl T obj, @NullableDecl String errorMessageTemplate, char p1) {
+  public static <T> T checkNotNull(@CheckForNull T obj, String errorMessageTemplate, char p1) {
     if (obj == null) {
       throw new NullPointerException(lenientFormat(errorMessageTemplate, p1));
     }
@@ -966,9 +958,7 @@ public static <T extends Object> T checkNotNull(
    * @since 20.0 (varargs overload since 2.0)
    */
   @CanIgnoreReturnValue
-  @NonNullDecl
-  public static <T extends Object> T checkNotNull(
-      @NonNullDecl T obj, @NullableDecl String errorMessageTemplate, int p1) {
+  public static <T> T checkNotNull(@CheckForNull T obj, String errorMessageTemplate, int p1) {
     if (obj == null) {
       throw new NullPointerException(lenientFormat(errorMessageTemplate, p1));
     }
@@ -983,9 +973,7 @@ public static <T extends Object> T checkNotNull(
    * @since 20.0 (varargs overload since 2.0)
    */
   @CanIgnoreReturnValue
-  @NonNullDecl
-  public static <T extends Object> T checkNotNull(
-      @NonNullDecl T obj, @NullableDecl String errorMessageTemplate, long p1) {
+  public static <T> T checkNotNull(@CheckForNull T obj, String errorMessageTemplate, long p1) {
     if (obj == null) {
       throw new NullPointerException(lenientFormat(errorMessageTemplate, p1));
     }
@@ -1000,9 +988,8 @@ public static <T extends Object> T checkNotNull(
    * @since 20.0 (varargs overload since 2.0)
    */
   @CanIgnoreReturnValue
-  @NonNullDecl
-  public static <T extends Object> T checkNotNull(
-      @NonNullDecl T obj, @NullableDecl String errorMessageTemplate, @NullableDecl Object p1) {
+  public static <T> T checkNotNull(
+      @CheckForNull T obj, String errorMessageTemplate, @CheckForNull Object p1) {
     if (obj == null) {
       throw new NullPointerException(lenientFormat(errorMessageTemplate, p1));
     }
@@ -1017,9 +1004,8 @@ public static <T extends Object> T checkNotNull(
    * @since 20.0 (varargs overload since 2.0)
    */
   @CanIgnoreReturnValue
-  @NonNullDecl
-  public static <T extends Object> T checkNotNull(
-      @NonNullDecl T obj, @NullableDecl String errorMessageTemplate, char p1, char p2) {
+  public static <T> T checkNotNull(
+      @CheckForNull T obj, String errorMessageTemplate, char p1, char p2) {
     if (obj == null) {
       throw new NullPointerException(lenientFormat(errorMessageTemplate, p1, p2));
     }
@@ -1034,9 +1020,8 @@ public static <T extends Object> T checkNotNull(
    * @since 20.0 (varargs overload since 2.0)
    */
   @CanIgnoreReturnValue
-  @NonNullDecl
-  public static <T extends Object> T checkNotNull(
-      @NonNullDecl T obj, @NullableDecl String errorMessageTemplate, char p1, int p2) {
+  public static <T> T checkNotNull(
+      @CheckForNull T obj, String errorMessageTemplate, char p1, int p2) {
     if (obj == null) {
       throw new NullPointerException(lenientFormat(errorMessageTemplate, p1, p2));
     }
@@ -1051,9 +1036,8 @@ public static <T extends Object> T checkNotNull(
    * @since 20.0 (varargs overload since 2.0)
    */
   @CanIgnoreReturnValue
-  @NonNullDecl
-  public static <T extends Object> T checkNotNull(
-      @NonNullDecl T obj, @NullableDecl String errorMessageTemplate, char p1, long p2) {
+  public static <T> T checkNotNull(
+      @CheckForNull T obj, String errorMessageTemplate, char p1, long p2) {
     if (obj == null) {
       throw new NullPointerException(lenientFormat(errorMessageTemplate, p1, p2));
     }
@@ -1068,12 +1052,8 @@ public static <T extends Object> T checkNotNull(
    * @since 20.0 (varargs overload since 2.0)
    */
   @CanIgnoreReturnValue
-  @NonNullDecl
-  public static <T extends Object> T checkNotNull(
-      @NonNullDecl T obj,
-      @NullableDecl String errorMessageTemplate,
-      char p1,
-      @NullableDecl Object p2) {
+  public static <T> T checkNotNull(
+      @CheckForNull T obj, String errorMessageTemplate, char p1, @CheckForNull Object p2) {
     if (obj == null) {
       throw new NullPointerException(lenientFormat(errorMessageTemplate, p1, p2));
     }
@@ -1088,9 +1068,8 @@ public static <T extends Object> T checkNotNull(
    * @since 20.0 (varargs overload since 2.0)
    */
   @CanIgnoreReturnValue
-  @NonNullDecl
-  public static <T extends Object> T checkNotNull(
-      @NonNullDecl T obj, @NullableDecl String errorMessageTemplate, int p1, char p2) {
+  public static <T> T checkNotNull(
+      @CheckForNull T obj, String errorMessageTemplate, int p1, char p2) {
     if (obj == null) {
       throw new NullPointerException(lenientFormat(errorMessageTemplate, p1, p2));
     }
@@ -1105,9 +1084,8 @@ public static <T extends Object> T checkNotNull(
    * @since 20.0 (varargs overload since 2.0)
    */
   @CanIgnoreReturnValue
-  @NonNullDecl
-  public static <T extends Object> T checkNotNull(
-      @NonNullDecl T obj, @NullableDecl String errorMessageTemplate, int p1, int p2) {
+  public static <T> T checkNotNull(
+      @CheckForNull T obj, String errorMessageTemplate, int p1, int p2) {
     if (obj == null) {
       throw new NullPointerException(lenientFormat(errorMessageTemplate, p1, p2));
     }
@@ -1122,9 +1100,8 @@ public static <T extends Object> T checkNotNull(
    * @since 20.0 (varargs overload since 2.0)
    */
   @CanIgnoreReturnValue
-  @NonNullDecl
-  public static <T extends Object> T checkNotNull(
-      @NonNullDecl T obj, @NullableDecl String errorMessageTemplate, int p1, long p2) {
+  public static <T> T checkNotNull(
+      @CheckForNull T obj, String errorMessageTemplate, int p1, long p2) {
     if (obj == null) {
       throw new NullPointerException(lenientFormat(errorMessageTemplate, p1, p2));
     }
@@ -1139,12 +1116,8 @@ public static <T extends Object> T checkNotNull(
    * @since 20.0 (varargs overload since 2.0)
    */
   @CanIgnoreReturnValue
-  @NonNullDecl
-  public static <T extends Object> T checkNotNull(
-      @NonNullDecl T obj,
-      @NullableDecl String errorMessageTemplate,
-      int p1,
-      @NullableDecl Object p2) {
+  public static <T> T checkNotNull(
+      @CheckForNull T obj, String errorMessageTemplate, int p1, @CheckForNull Object p2) {
     if (obj == null) {
       throw new NullPointerException(lenientFormat(errorMessageTemplate, p1, p2));
     }
@@ -1159,9 +1132,8 @@ public static <T extends Object> T checkNotNull(
    * @since 20.0 (varargs overload since 2.0)
    */
   @CanIgnoreReturnValue
-  @NonNullDecl
-  public static <T extends Object> T checkNotNull(
-      @NonNullDecl T obj, @NullableDecl String errorMessageTemplate, long p1, char p2) {
+  public static <T> T checkNotNull(
+      @CheckForNull T obj, String errorMessageTemplate, long p1, char p2) {
     if (obj == null) {
       throw new NullPointerException(lenientFormat(errorMessageTemplate, p1, p2));
     }
@@ -1176,9 +1148,8 @@ public static <T extends Object> T checkNotNull(
    * @since 20.0 (varargs overload since 2.0)
    */
   @CanIgnoreReturnValue
-  @NonNullDecl
-  public static <T extends Object> T checkNotNull(
-      @NonNullDecl T obj, @NullableDecl String errorMessageTemplate, long p1, int p2) {
+  public static <T> T checkNotNull(
+      @CheckForNull T obj, String errorMessageTemplate, long p1, int p2) {
     if (obj == null) {
       throw new NullPointerException(lenientFormat(errorMessageTemplate, p1, p2));
     }
@@ -1193,9 +1164,8 @@ public static <T extends Object> T checkNotNull(
    * @since 20.0 (varargs overload since 2.0)
    */
   @CanIgnoreReturnValue
-  @NonNullDecl
-  public static <T extends Object> T checkNotNull(
-      @NonNullDecl T obj, @NullableDecl String errorMessageTemplate, long p1, long p2) {
+  public static <T> T checkNotNull(
+      @CheckForNull T obj, String errorMessageTemplate, long p1, long p2) {
     if (obj == null) {
       throw new NullPointerException(lenientFormat(errorMessageTemplate, p1, p2));
     }
@@ -1210,12 +1180,8 @@ public static <T extends Object> T checkNotNull(
    * @since 20.0 (varargs overload since 2.0)
    */
   @CanIgnoreReturnValue
-  @NonNullDecl
-  public static <T extends Object> T checkNotNull(
-      @NonNullDecl T obj,
-      @NullableDecl String errorMessageTemplate,
-      long p1,
-      @NullableDecl Object p2) {
+  public static <T> T checkNotNull(
+      @CheckForNull T obj, String errorMessageTemplate, long p1, @CheckForNull Object p2) {
     if (obj == null) {
       throw new NullPointerException(lenientFormat(errorMessageTemplate, p1, p2));
     }
@@ -1230,12 +1196,8 @@ public static <T extends Object> T checkNotNull(
    * @since 20.0 (varargs overload since 2.0)
    */
   @CanIgnoreReturnValue
-  @NonNullDecl
-  public static <T extends Object> T checkNotNull(
-      @NonNullDecl T obj,
-      @NullableDecl String errorMessageTemplate,
-      @NullableDecl Object p1,
-      char p2) {
+  public static <T> T checkNotNull(
+      @CheckForNull T obj, String errorMessageTemplate, @CheckForNull Object p1, char p2) {
     if (obj == null) {
       throw new NullPointerException(lenientFormat(errorMessageTemplate, p1, p2));
     }
@@ -1250,12 +1212,8 @@ public static <T extends Object> T checkNotNull(
    * @since 20.0 (varargs overload since 2.0)
    */
   @CanIgnoreReturnValue
-  @NonNullDecl
-  public static <T extends Object> T checkNotNull(
-      @NonNullDecl T obj,
-      @NullableDecl String errorMessageTemplate,
-      @NullableDecl Object p1,
-      int p2) {
+  public static <T> T checkNotNull(
+      @CheckForNull T obj, String errorMessageTemplate, @CheckForNull Object p1, int p2) {
     if (obj == null) {
       throw new NullPointerException(lenientFormat(errorMessageTemplate, p1, p2));
     }
@@ -1270,12 +1228,8 @@ public static <T extends Object> T checkNotNull(
    * @since 20.0 (varargs overload since 2.0)
    */
   @CanIgnoreReturnValue
-  @NonNullDecl
-  public static <T extends Object> T checkNotNull(
-      @NonNullDecl T obj,
-      @NullableDecl String errorMessageTemplate,
-      @NullableDecl Object p1,
-      long p2) {
+  public static <T> T checkNotNull(
+      @CheckForNull T obj, String errorMessageTemplate, @CheckForNull Object p1, long p2) {
     if (obj == null) {
       throw new NullPointerException(lenientFormat(errorMessageTemplate, p1, p2));
     }
@@ -1290,12 +1244,11 @@ public static <T extends Object> T checkNotNull(
    * @since 20.0 (varargs overload since 2.0)
    */
   @CanIgnoreReturnValue
-  @NonNullDecl
-  public static <T extends Object> T checkNotNull(
-      @NonNullDecl T obj,
-      @NullableDecl String errorMessageTemplate,
-      @NullableDecl Object p1,
-      @NullableDecl Object p2) {
+  public static <T> T checkNotNull(
+      @CheckForNull T obj,
+      String errorMessageTemplate,
+      @CheckForNull Object p1,
+      @CheckForNull Object p2) {
     if (obj == null) {
       throw new NullPointerException(lenientFormat(errorMessageTemplate, p1, p2));
     }
@@ -1310,13 +1263,12 @@ public static <T extends Object> T checkNotNull(
    * @since 20.0 (varargs overload since 2.0)
    */
   @CanIgnoreReturnValue
-  @NonNullDecl
-  public static <T extends Object> T checkNotNull(
-      @NonNullDecl T obj,
-      @NullableDecl String errorMessageTemplate,
-      @NullableDecl Object p1,
-      @NullableDecl Object p2,
-      @NullableDecl Object p3) {
+  public static <T> T checkNotNull(
+      @CheckForNull T obj,
+      String errorMessageTemplate,
+      @CheckForNull Object p1,
+      @CheckForNull Object p2,
+      @CheckForNull Object p3) {
     if (obj == null) {
       throw new NullPointerException(lenientFormat(errorMessageTemplate, p1, p2, p3));
     }
@@ -1331,14 +1283,13 @@ public static <T extends Object> T checkNotNull(
    * @since 20.0 (varargs overload since 2.0)
    */
   @CanIgnoreReturnValue
-  @NonNullDecl
-  public static <T extends Object> T checkNotNull(
-      @NonNullDecl T obj,
-      @NullableDecl String errorMessageTemplate,
-      @NullableDecl Object p1,
-      @NullableDecl Object p2,
-      @NullableDecl Object p3,
-      @NullableDecl Object p4) {
+  public static <T> T checkNotNull(
+      @CheckForNull T obj,
+      String errorMessageTemplate,
+      @CheckForNull Object p1,
+      @CheckForNull Object p2,
+      @CheckForNull Object p3,
+      @CheckForNull Object p4) {
     if (obj == null) {
       throw new NullPointerException(lenientFormat(errorMessageTemplate, p1, p2, p3, p4));
     }
@@ -1398,7 +1349,7 @@ public static int checkElementIndex(int index, int size) {
    * @throws IllegalArgumentException if {@code size} is negative
    */
   @CanIgnoreReturnValue
-  public static int checkElementIndex(int index, int size, @NullableDecl String desc) {
+  public static int checkElementIndex(int index, int size, String desc) {
     // Carefully optimized for execution by hotspot (explanatory comment above)
     if (index < 0 || index >= size) {
       throw new IndexOutOfBoundsException(badElementIndex(index, size, desc));
@@ -1406,7 +1357,7 @@ public static int checkElementIndex(int index, int size, @NullableDecl String de
     return index;
   }
 
-  private static String badElementIndex(int index, int size, @NullableDecl String desc) {
+  private static String badElementIndex(int index, int size, String desc) {
     if (index < 0) {
       return lenientFormat("%s (%s) must not be negative", desc, index);
     } else if (size < 0) {
@@ -1443,7 +1394,7 @@ public static int checkPositionIndex(int index, int size) {
    * @throws IllegalArgumentException if {@code size} is negative
    */
   @CanIgnoreReturnValue
-  public static int checkPositionIndex(int index, int size, @NullableDecl String desc) {
+  public static int checkPositionIndex(int index, int size, String desc) {
     // Carefully optimized for execution by hotspot (explanatory comment above)
     if (index < 0 || index > size) {
       throw new IndexOutOfBoundsException(badPositionIndex(index, size, desc));
@@ -1451,7 +1402,7 @@ public static int checkPositionIndex(int index, int size, @NullableDecl String d
     return index;
   }
 
-  private static String badPositionIndex(int index, int size, @NullableDecl String desc) {
+  private static String badPositionIndex(int index, int size, String desc) {
     if (index < 0) {
       return lenientFormat("%s (%s) must not be negative", desc, index);
     } else if (size < 0) {
@@ -1490,21 +1441,4 @@ private static String badPositionIndexes(int start, int end, int size) {
     // end < start
     return lenientFormat("end index (%s) must not be less than start index (%s)", end, start);
   }
-
-  static {
-    try {
-      Java8Usage.performCheck();
-    } catch (Throwable underlying) {
-      Exception toLog =
-          new Exception(
-              "Guava will drop support for Java 7 in 2021. Please let us know if this will cause"
-                  + " you problems: https://github.com/google/guava/issues/5269",
-              underlying);
-      Logger.getLogger(Preconditions.class.getName())
-          .log(
-              WARNING,
-              "Java 7 compatibility warning: See https://github.com/google/guava/issues/5269",
-              toLog);
-    }
-  }
 }
diff --git a/android/guava/src/com/google/common/base/Predicate.java b/android/guava/src/com/google/common/base/Predicate.java
index e0627255012f..35d57a6018a2 100644
--- a/android/guava/src/com/google/common/base/Predicate.java
+++ b/android/guava/src/com/google/common/base/Predicate.java
@@ -16,7 +16,8 @@
 
 import com.google.common.annotations.GwtCompatible;
 import com.google.errorprone.annotations.CanIgnoreReturnValue;
-import org.checkerframework.checker.nullness.compatqual.NullableDecl;
+import javax.annotation.CheckForNull;
+import org.checkerframework.checker.nullness.qual.Nullable;
 
 /**
  * Determines a true or false value for a given input; a pre-Java-8 version of {@link
@@ -45,7 +46,8 @@
  * @since 2.0
  */
 @GwtCompatible
-public interface Predicate<T> {
+@ElementTypesAreNonnullByDefault
+public interface Predicate<T extends @Nullable Object> {
   /**
    * Returns the result of applying this predicate to {@code input} (Java 8 users, see notes in the
    * class documentation above). This method is <i>generally expected</i>, but not absolutely
@@ -62,7 +64,7 @@ public interface Predicate<T> {
    *     arguments
    */
   @CanIgnoreReturnValue
-  boolean apply(@NullableDecl T input);
+  boolean apply(@ParametricNullness T input);
 
   /**
    * Indicates whether another object is equal to this predicate.
@@ -75,5 +77,5 @@ public interface Predicate<T> {
    * predicates are known <i>not</i> to be interchangeable.
    */
   @Override
-  boolean equals(@NullableDecl Object object);
+  boolean equals(@CheckForNull Object object);
 }
diff --git a/android/guava/src/com/google/common/base/Predicates.java b/android/guava/src/com/google/common/base/Predicates.java
index 9c8f1e5ea256..dc487fc56ffa 100644
--- a/android/guava/src/com/google/common/base/Predicates.java
+++ b/android/guava/src/com/google/common/base/Predicates.java
@@ -25,7 +25,8 @@
 import java.util.Collection;
 import java.util.List;
 import java.util.regex.Pattern;
-import org.checkerframework.checker.nullness.compatqual.NullableDecl;
+import javax.annotation.CheckForNull;
+import org.checkerframework.checker.nullness.qual.Nullable;
 
 /**
  * Static utility methods pertaining to {@code Predicate} instances.
@@ -39,6 +40,7 @@
  * @since 2.0
  */
 @GwtCompatible(emulated = true)
+@ElementTypesAreNonnullByDefault
 public final class Predicates {
   private Predicates() {}
 
@@ -47,13 +49,13 @@ private Predicates() {}
 
   /** Returns a predicate that always evaluates to {@code true}. */
   @GwtCompatible(serializable = true)
-  public static <T> Predicate<T> alwaysTrue() {
+  public static <T extends @Nullable Object> Predicate<T> alwaysTrue() {
     return ObjectPredicate.ALWAYS_TRUE.withNarrowedType();
   }
 
   /** Returns a predicate that always evaluates to {@code false}. */
   @GwtCompatible(serializable = true)
-  public static <T> Predicate<T> alwaysFalse() {
+  public static <T extends @Nullable Object> Predicate<T> alwaysFalse() {
     return ObjectPredicate.ALWAYS_FALSE.withNarrowedType();
   }
 
@@ -62,7 +64,7 @@ public static <T> Predicate<T> alwaysFalse() {
    * null.
    */
   @GwtCompatible(serializable = true)
-  public static <T> Predicate<T> isNull() {
+  public static <T extends @Nullable Object> Predicate<T> isNull() {
     return ObjectPredicate.IS_NULL.withNarrowedType();
   }
 
@@ -71,7 +73,7 @@ public static <T> Predicate<T> isNull() {
    * null.
    */
   @GwtCompatible(serializable = true)
-  public static <T> Predicate<T> notNull() {
+  public static <T extends @Nullable Object> Predicate<T> notNull() {
     return ObjectPredicate.NOT_NULL.withNarrowedType();
   }
 
@@ -79,8 +81,8 @@ public static <T> Predicate<T> notNull() {
    * Returns a predicate that evaluates to {@code true} if the given predicate evaluates to {@code
    * false}.
    */
-  public static <T> Predicate<T> not(Predicate<T> predicate) {
-    return new NotPredicate<T>(predicate);
+  public static <T extends @Nullable Object> Predicate<T> not(Predicate<T> predicate) {
+    return new NotPredicate<>(predicate);
   }
 
   /**
@@ -90,8 +92,9 @@ public static <T> Predicate<T> not(Predicate<T> predicate) {
    * changes to it won't alter the behavior of this predicate. If {@code components} is empty, the
    * returned predicate will always evaluate to {@code true}.
    */
-  public static <T> Predicate<T> and(Iterable<? extends Predicate<? super T>> components) {
-    return new AndPredicate<T>(defensiveCopy(components));
+  public static <T extends @Nullable Object> Predicate<T> and(
+      Iterable<? extends Predicate<? super T>> components) {
+    return new AndPredicate<>(defensiveCopy(components));
   }
 
   /**
@@ -102,7 +105,7 @@ public static <T> Predicate<T> and(Iterable<? extends Predicate<? super T>> comp
    * returned predicate will always evaluate to {@code true}.
    */
   @SafeVarargs
-  public static <T> Predicate<T> and(Predicate<? super T>... components) {
+  public static <T extends @Nullable Object> Predicate<T> and(Predicate<? super T>... components) {
     return new AndPredicate<T>(defensiveCopy(components));
   }
 
@@ -111,8 +114,9 @@ public static <T> Predicate<T> and(Predicate<? super T>... components) {
    * true}. The components are evaluated in order, and evaluation will be "short-circuited" as soon
    * as a false predicate is found.
    */
-  public static <T> Predicate<T> and(Predicate<? super T> first, Predicate<? super T> second) {
-    return new AndPredicate<T>(Predicates.<T>asList(checkNotNull(first), checkNotNull(second)));
+  public static <T extends @Nullable Object> Predicate<T> and(
+      Predicate<? super T> first, Predicate<? super T> second) {
+    return new AndPredicate<>(Predicates.<T>asList(checkNotNull(first), checkNotNull(second)));
   }
 
   /**
@@ -122,8 +126,9 @@ public static <T> Predicate<T> and(Predicate<? super T> first, Predicate<? super
    * changes to it won't alter the behavior of this predicate. If {@code components} is empty, the
    * returned predicate will always evaluate to {@code false}.
    */
-  public static <T> Predicate<T> or(Iterable<? extends Predicate<? super T>> components) {
-    return new OrPredicate<T>(defensiveCopy(components));
+  public static <T extends @Nullable Object> Predicate<T> or(
+      Iterable<? extends Predicate<? super T>> components) {
+    return new OrPredicate<>(defensiveCopy(components));
   }
 
   /**
@@ -134,7 +139,7 @@ public static <T> Predicate<T> or(Iterable<? extends Predicate<? super T>> compo
    * returned predicate will always evaluate to {@code false}.
    */
   @SafeVarargs
-  public static <T> Predicate<T> or(Predicate<? super T>... components) {
+  public static <T extends @Nullable Object> Predicate<T> or(Predicate<? super T>... components) {
     return new OrPredicate<T>(defensiveCopy(components));
   }
 
@@ -143,16 +148,19 @@ public static <T> Predicate<T> or(Predicate<? super T>... components) {
    * {@code true}. The components are evaluated in order, and evaluation will be "short-circuited"
    * as soon as a true predicate is found.
    */
-  public static <T> Predicate<T> or(Predicate<? super T> first, Predicate<? super T> second) {
-    return new OrPredicate<T>(Predicates.<T>asList(checkNotNull(first), checkNotNull(second)));
+  public static <T extends @Nullable Object> Predicate<T> or(
+      Predicate<? super T> first, Predicate<? super T> second) {
+    return new OrPredicate<>(Predicates.<T>asList(checkNotNull(first), checkNotNull(second)));
   }
 
   /**
    * Returns a predicate that evaluates to {@code true} if the object being tested {@code equals()}
    * the given target or both are null.
    */
-  public static <T> Predicate<T> equalTo(@NullableDecl T target) {
-    return (target == null) ? Predicates.<T>isNull() : new IsEqualToPredicate<T>(target);
+  public static <T extends @Nullable Object> Predicate<T> equalTo(@ParametricNullness T target) {
+    return (target == null)
+        ? Predicates.<T>isNull()
+        : new IsEqualToPredicate(target).withNarrowedType();
   }
 
   /**
@@ -169,8 +177,8 @@ public static <T> Predicate<T> equalTo(@NullableDecl T target) {
    * instances {@code Lists.newArrayList(1)} and {@code Arrays.asList(1)}.
    */
   @GwtIncompatible // Class.isInstance
-  public static Predicate<Object> instanceOf(Class<?> clazz) {
-    return new InstanceOfPredicate(clazz);
+  public static <T extends @Nullable Object> Predicate<T> instanceOf(Class<?> clazz) {
+    return new InstanceOfPredicate<>(clazz);
   }
 
   /**
@@ -204,8 +212,8 @@ public static Predicate<Class<?>> subtypeOf(Class<?> clazz) {
    *
    * @param target the collection that may contain the function input
    */
-  public static <T> Predicate<T> in(Collection<? extends T> target) {
-    return new InPredicate<T>(target);
+  public static <T extends @Nullable Object> Predicate<T> in(Collection<? extends T> target) {
+    return new InPredicate<>(target);
   }
 
   /**
@@ -214,7 +222,7 @@ public static <T> Predicate<T> in(Collection<? extends T> target) {
    *
    * @return the composition of the provided function and predicate
    */
-  public static <A, B> Predicate<A> compose(
+  public static <A extends @Nullable Object, B extends @Nullable Object> Predicate<A> compose(
       Predicate<B> predicate, Function<A, ? extends B> function) {
     return new CompositionPredicate<>(predicate, function);
   }
@@ -247,11 +255,11 @@ public static Predicate<CharSequence> contains(Pattern pattern) {
   // End public API, begin private implementation classes.
 
   // Package private for GWT serialization.
-  enum ObjectPredicate implements Predicate<Object> {
+  enum ObjectPredicate implements Predicate<@Nullable Object> {
     /** @see Predicates#alwaysTrue() */
     ALWAYS_TRUE {
       @Override
-      public boolean apply(@NullableDecl Object o) {
+      public boolean apply(@CheckForNull Object o) {
         return true;
       }
 
@@ -263,7 +271,7 @@ public String toString() {
     /** @see Predicates#alwaysFalse() */
     ALWAYS_FALSE {
       @Override
-      public boolean apply(@NullableDecl Object o) {
+      public boolean apply(@CheckForNull Object o) {
         return false;
       }
 
@@ -275,7 +283,7 @@ public String toString() {
     /** @see Predicates#isNull() */
     IS_NULL {
       @Override
-      public boolean apply(@NullableDecl Object o) {
+      public boolean apply(@CheckForNull Object o) {
         return o == null;
       }
 
@@ -287,7 +295,7 @@ public String toString() {
     /** @see Predicates#notNull() */
     NOT_NULL {
       @Override
-      public boolean apply(@NullableDecl Object o) {
+      public boolean apply(@CheckForNull Object o) {
         return o != null;
       }
 
@@ -298,13 +306,14 @@ public String toString() {
     };
 
     @SuppressWarnings("unchecked") // safe contravariant cast
-    <T> Predicate<T> withNarrowedType() {
+    <T extends @Nullable Object> Predicate<T> withNarrowedType() {
       return (Predicate<T>) this;
     }
   }
 
   /** @see Predicates#not(Predicate) */
-  private static class NotPredicate<T> implements Predicate<T>, Serializable {
+  private static class NotPredicate<T extends @Nullable Object>
+      implements Predicate<T>, Serializable {
     final Predicate<T> predicate;
 
     NotPredicate(Predicate<T> predicate) {
@@ -312,7 +321,7 @@ private static class NotPredicate<T> implements Predicate<T>, Serializable {
     }
 
     @Override
-    public boolean apply(@NullableDecl T t) {
+    public boolean apply(@ParametricNullness T t) {
       return !predicate.apply(t);
     }
 
@@ -322,7 +331,7 @@ public int hashCode() {
     }
 
     @Override
-    public boolean equals(@NullableDecl Object obj) {
+    public boolean equals(@CheckForNull Object obj) {
       if (obj instanceof NotPredicate) {
         NotPredicate<?> that = (NotPredicate<?>) obj;
         return predicate.equals(that.predicate);
@@ -339,7 +348,8 @@ public String toString() {
   }
 
   /** @see Predicates#and(Iterable) */
-  private static class AndPredicate<T> implements Predicate<T>, Serializable {
+  private static class AndPredicate<T extends @Nullable Object>
+      implements Predicate<T>, Serializable {
     private final List<? extends Predicate<? super T>> components;
 
     private AndPredicate(List<? extends Predicate<? super T>> components) {
@@ -347,7 +357,7 @@ private AndPredicate(List<? extends Predicate<? super T>> components) {
     }
 
     @Override
-    public boolean apply(@NullableDecl T t) {
+    public boolean apply(@ParametricNullness T t) {
       // Avoid using the Iterator to avoid generating garbage (issue 820).
       for (int i = 0; i < components.size(); i++) {
         if (!components.get(i).apply(t)) {
@@ -364,7 +374,7 @@ public int hashCode() {
     }
 
     @Override
-    public boolean equals(@NullableDecl Object obj) {
+    public boolean equals(@CheckForNull Object obj) {
       if (obj instanceof AndPredicate) {
         AndPredicate<?> that = (AndPredicate<?>) obj;
         return components.equals(that.components);
@@ -381,7 +391,8 @@ public String toString() {
   }
 
   /** @see Predicates#or(Iterable) */
-  private static class OrPredicate<T> implements Predicate<T>, Serializable {
+  private static class OrPredicate<T extends @Nullable Object>
+      implements Predicate<T>, Serializable {
     private final List<? extends Predicate<? super T>> components;
 
     private OrPredicate(List<? extends Predicate<? super T>> components) {
@@ -389,7 +400,7 @@ private OrPredicate(List<? extends Predicate<? super T>> components) {
     }
 
     @Override
-    public boolean apply(@NullableDecl T t) {
+    public boolean apply(@ParametricNullness T t) {
       // Avoid using the Iterator to avoid generating garbage (issue 820).
       for (int i = 0; i < components.size(); i++) {
         if (components.get(i).apply(t)) {
@@ -406,7 +417,7 @@ public int hashCode() {
     }
 
     @Override
-    public boolean equals(@NullableDecl Object obj) {
+    public boolean equals(@CheckForNull Object obj) {
       if (obj instanceof OrPredicate) {
         OrPredicate<?> that = (OrPredicate<?>) obj;
         return components.equals(that.components);
@@ -436,16 +447,16 @@ private static String toStringHelper(String methodName, Iterable<?> components)
   }
 
   /** @see Predicates#equalTo(Object) */
-  private static class IsEqualToPredicate<T> implements Predicate<T>, Serializable {
-    private final T target;
+  private static class IsEqualToPredicate implements Predicate<@Nullable Object>, Serializable {
+    private final Object target;
 
-    private IsEqualToPredicate(T target) {
+    private IsEqualToPredicate(Object target) {
       this.target = target;
     }
 
     @Override
-    public boolean apply(T t) {
-      return target.equals(t);
+    public boolean apply(@CheckForNull Object o) {
+      return target.equals(o);
     }
 
     @Override
@@ -454,9 +465,9 @@ public int hashCode() {
     }
 
     @Override
-    public boolean equals(@NullableDecl Object obj) {
+    public boolean equals(@CheckForNull Object obj) {
       if (obj instanceof IsEqualToPredicate) {
-        IsEqualToPredicate<?> that = (IsEqualToPredicate<?>) obj;
+        IsEqualToPredicate that = (IsEqualToPredicate) obj;
         return target.equals(that.target);
       }
       return false;
@@ -468,11 +479,17 @@ public String toString() {
     }
 
     private static final long serialVersionUID = 0;
+
+    @SuppressWarnings("unchecked") // safe contravariant cast
+    <T extends @Nullable Object> Predicate<T> withNarrowedType() {
+      return (Predicate<T>) this;
+    }
   }
 
   /** @see Predicates#instanceOf(Class) */
   @GwtIncompatible // Class.isInstance
-  private static class InstanceOfPredicate implements Predicate<Object>, Serializable {
+  private static class InstanceOfPredicate<T extends @Nullable Object>
+      implements Predicate<T>, Serializable {
     private final Class<?> clazz;
 
     private InstanceOfPredicate(Class<?> clazz) {
@@ -480,7 +497,7 @@ private InstanceOfPredicate(Class<?> clazz) {
     }
 
     @Override
-    public boolean apply(@NullableDecl Object o) {
+    public boolean apply(@ParametricNullness T o) {
       return clazz.isInstance(o);
     }
 
@@ -490,9 +507,9 @@ public int hashCode() {
     }
 
     @Override
-    public boolean equals(@NullableDecl Object obj) {
+    public boolean equals(@CheckForNull Object obj) {
       if (obj instanceof InstanceOfPredicate) {
-        InstanceOfPredicate that = (InstanceOfPredicate) obj;
+        InstanceOfPredicate<?> that = (InstanceOfPredicate<?>) obj;
         return clazz == that.clazz;
       }
       return false;
@@ -526,7 +543,7 @@ public int hashCode() {
     }
 
     @Override
-    public boolean equals(@NullableDecl Object obj) {
+    public boolean equals(@CheckForNull Object obj) {
       if (obj instanceof SubtypeOfPredicate) {
         SubtypeOfPredicate that = (SubtypeOfPredicate) obj;
         return clazz == that.clazz;
@@ -543,7 +560,8 @@ public String toString() {
   }
 
   /** @see Predicates#in(Collection) */
-  private static class InPredicate<T> implements Predicate<T>, Serializable {
+  private static class InPredicate<T extends @Nullable Object>
+      implements Predicate<T>, Serializable {
     private final Collection<?> target;
 
     private InPredicate(Collection<?> target) {
@@ -551,7 +569,7 @@ private InPredicate(Collection<?> target) {
     }
 
     @Override
-    public boolean apply(@NullableDecl T t) {
+    public boolean apply(@ParametricNullness T t) {
       try {
         return target.contains(t);
       } catch (NullPointerException | ClassCastException e) {
@@ -560,7 +578,7 @@ public boolean apply(@NullableDecl T t) {
     }
 
     @Override
-    public boolean equals(@NullableDecl Object obj) {
+    public boolean equals(@CheckForNull Object obj) {
       if (obj instanceof InPredicate) {
         InPredicate<?> that = (InPredicate<?>) obj;
         return target.equals(that.target);
@@ -582,7 +600,8 @@ public String toString() {
   }
 
   /** @see Predicates#compose(Predicate, Function) */
-  private static class CompositionPredicate<A, B> implements Predicate<A>, Serializable {
+  private static class CompositionPredicate<A extends @Nullable Object, B extends @Nullable Object>
+      implements Predicate<A>, Serializable {
     final Predicate<B> p;
     final Function<A, ? extends B> f;
 
@@ -592,12 +611,12 @@ private CompositionPredicate(Predicate<B> p, Function<A, ? extends B> f) {
     }
 
     @Override
-    public boolean apply(@NullableDecl A a) {
+    public boolean apply(@ParametricNullness A a) {
       return p.apply(f.apply(a));
     }
 
     @Override
-    public boolean equals(@NullableDecl Object obj) {
+    public boolean equals(@CheckForNull Object obj) {
       if (obj instanceof CompositionPredicate) {
         CompositionPredicate<?, ?> that = (CompositionPredicate<?, ?>) obj;
         return f.equals(that.f) && p.equals(that.p);
@@ -642,7 +661,7 @@ public int hashCode() {
     }
 
     @Override
-    public boolean equals(@NullableDecl Object obj) {
+    public boolean equals(@CheckForNull Object obj) {
       if (obj instanceof ContainsPatternPredicate) {
         ContainsPatternPredicate that = (ContainsPatternPredicate) obj;
 
@@ -683,7 +702,7 @@ public String toString() {
     private static final long serialVersionUID = 0;
   }
 
-  private static <T> List<Predicate<? super T>> asList(
+  private static <T extends @Nullable Object> List<Predicate<? super T>> asList(
       Predicate<? super T> first, Predicate<? super T> second) {
     // TODO(kevinb): understand why we still get a warning despite @SafeVarargs!
     return Arrays.<Predicate<? super T>>asList(first, second);
@@ -694,7 +713,7 @@ private static <T> List<T> defensiveCopy(T... array) {
   }
 
   static <T> List<T> defensiveCopy(Iterable<T> iterable) {
-    ArrayList<T> list = new ArrayList<T>();
+    ArrayList<T> list = new ArrayList<>();
     for (T element : iterable) {
       list.add(checkNotNull(element));
     }
diff --git a/android/guava/src/com/google/common/base/Present.java b/android/guava/src/com/google/common/base/Present.java
index d33eb8e38567..4e62da29e93b 100644
--- a/android/guava/src/com/google/common/base/Present.java
+++ b/android/guava/src/com/google/common/base/Present.java
@@ -19,10 +19,11 @@
 import com.google.common.annotations.GwtCompatible;
 import java.util.Collections;
 import java.util.Set;
-import org.checkerframework.checker.nullness.compatqual.NullableDecl;
+import javax.annotation.CheckForNull;
 
 /** Implementation of an {@link Optional} containing a reference. */
 @GwtCompatible
+@ElementTypesAreNonnullByDefault
 final class Present<T> extends Optional<T> {
   private final T reference;
 
@@ -70,14 +71,14 @@ public Set<T> asSet() {
 
   @Override
   public <V> Optional<V> transform(Function<? super T, V> function) {
-    return new Present<V>(
+    return new Present<>(
         checkNotNull(
             function.apply(reference),
             "the Function passed to Optional.transform() must not return null."));
   }
 
   @Override
-  public boolean equals(@NullableDecl Object object) {
+  public boolean equals(@CheckForNull Object object) {
     if (object instanceof Present) {
       Present<?> other = (Present<?>) object;
       return reference.equals(other.reference);
diff --git a/android/guava/src/com/google/common/base/SmallCharMatcher.java b/android/guava/src/com/google/common/base/SmallCharMatcher.java
index 1e565c858b96..f0e801b67118 100644
--- a/android/guava/src/com/google/common/base/SmallCharMatcher.java
+++ b/android/guava/src/com/google/common/base/SmallCharMatcher.java
@@ -26,6 +26,7 @@
  * @author Christopher Swenson
  */
 @GwtIncompatible // no precomputation is done in GWT
+@ElementTypesAreNonnullByDefault
 final class SmallCharMatcher extends NamedFastMatcher {
   static final int MAX_SIZE = 1023;
   private final char[] table;
diff --git a/android/guava/src/com/google/common/base/Splitter.java b/android/guava/src/com/google/common/base/Splitter.java
index 150c2fe4d09c..bde2e0ec42f8 100644
--- a/android/guava/src/com/google/common/base/Splitter.java
+++ b/android/guava/src/com/google/common/base/Splitter.java
@@ -27,6 +27,7 @@
 import java.util.List;
 import java.util.Map;
 import java.util.regex.Pattern;
+import javax.annotation.CheckForNull;
 
 /**
  * Extracts non-overlapping substrings from an input string, typically by recognizing appearances of
@@ -97,6 +98,7 @@
  * @since 1.0
  */
 @GwtCompatible(emulated = true)
+@ElementTypesAreNonnullByDefault
 public final class Splitter {
   private final CharMatcher trimmer;
   private final boolean omitEmptyStrings;
@@ -547,6 +549,7 @@ protected SplittingIterator(Splitter splitter, CharSequence toSplit) {
       this.toSplit = toSplit;
     }
 
+    @CheckForNull
     @Override
     protected String computeNext() {
       /*
diff --git a/android/guava/src/com/google/common/base/StandardSystemProperty.java b/android/guava/src/com/google/common/base/StandardSystemProperty.java
index bf86128e81a6..dc29792de782 100644
--- a/android/guava/src/com/google/common/base/StandardSystemProperty.java
+++ b/android/guava/src/com/google/common/base/StandardSystemProperty.java
@@ -15,7 +15,7 @@
 package com.google.common.base;
 
 import com.google.common.annotations.GwtIncompatible;
-import org.checkerframework.checker.nullness.compatqual.NullableDecl;
+import javax.annotation.CheckForNull;
 
 /**
  * Represents a {@linkplain System#getProperties() standard system property}.
@@ -24,6 +24,7 @@
  * @since 15.0
  */
 @GwtIncompatible // java.lang.System#getProperty
+@ElementTypesAreNonnullByDefault
 public enum StandardSystemProperty {
 
   /** Java Runtime Environment version. */
@@ -152,7 +153,7 @@ public String key() {
    *   <li>{@code jdk.module.*} (added in Java 9, optional)
    * </ul>
    */
-  @NullableDecl
+  @CheckForNull
   public String value() {
     return System.getProperty(key);
   }
diff --git a/android/guava/src/com/google/common/base/Stopwatch.java b/android/guava/src/com/google/common/base/Stopwatch.java
index 4a6767d15e57..f76c098613a9 100644
--- a/android/guava/src/com/google/common/base/Stopwatch.java
+++ b/android/guava/src/com/google/common/base/Stopwatch.java
@@ -77,7 +77,7 @@
  * Stopwatch.createStarted(
  *      new Ticker() {
  *        public long read() {
- *          return android.os.SystemClock.elapsedRealtimeNanos();
+ *          return android.os.SystemClock.elapsedRealtimeNanos(); // requires API Level 17
  *        }
  *      });
  * }</pre>
@@ -85,8 +85,9 @@
  * @author Kevin Bourrillion
  * @since 10.0
  */
-@GwtCompatible
+@GwtCompatible(emulated = true)
 @SuppressWarnings("GoodTime") // lots of violations
+@ElementTypesAreNonnullByDefault
 public final class Stopwatch {
   private final Ticker ticker;
   private boolean isRunning;
diff --git a/android/guava/src/com/google/common/base/Strings.java b/android/guava/src/com/google/common/base/Strings.java
index 475851706e71..fa3626648d10 100644
--- a/android/guava/src/com/google/common/base/Strings.java
+++ b/android/guava/src/com/google/common/base/Strings.java
@@ -21,7 +21,8 @@
 import com.google.common.annotations.GwtCompatible;
 import com.google.common.annotations.VisibleForTesting;
 import java.util.logging.Logger;
-import org.checkerframework.checker.nullness.compatqual.NullableDecl;
+import javax.annotation.CheckForNull;
+import org.checkerframework.checker.nullness.qual.Nullable;
 
 /**
  * Static utility methods pertaining to {@code String} or {@code CharSequence} instances.
@@ -30,6 +31,7 @@
  * @since 3.0
  */
 @GwtCompatible
+@ElementTypesAreNonnullByDefault
 public final class Strings {
   private Strings() {}
 
@@ -39,7 +41,7 @@ private Strings() {}
    * @param string the string to test and possibly return
    * @return {@code string} itself if it is non-null; {@code ""} if it is null
    */
-  public static String nullToEmpty(@NullableDecl String string) {
+  public static String nullToEmpty(@CheckForNull String string) {
     return Platform.nullToEmpty(string);
   }
 
@@ -49,8 +51,8 @@ public static String nullToEmpty(@NullableDecl String string) {
    * @param string the string to test and possibly return
    * @return {@code string} itself if it is nonempty; {@code null} if it is empty or null
    */
-  @NullableDecl
-  public static String emptyToNull(@NullableDecl String string) {
+  @CheckForNull
+  public static String emptyToNull(@CheckForNull String string) {
     return Platform.emptyToNull(string);
   }
 
@@ -65,7 +67,7 @@ public static String emptyToNull(@NullableDecl String string) {
    * @param string a string reference to check
    * @return {@code true} if the string is null or is the empty string
    */
-  public static boolean isNullOrEmpty(@NullableDecl String string) {
+  public static boolean isNullOrEmpty(@CheckForNull String string) {
     return Platform.stringIsNullOrEmpty(string);
   }
 
@@ -257,7 +259,8 @@ static boolean validSurrogatePairAt(CharSequence string, int index) {
    * @since 25.1
    */
   // TODO(diamondm) consider using Arrays.toString() for array parameters
-  public static String lenientFormat(@NullableDecl String template, @NullableDecl Object... args) {
+  public static String lenientFormat(
+      @CheckForNull String template, @CheckForNull @Nullable Object... args) {
     template = String.valueOf(template); // null -> "null"
 
     if (args == null) {
@@ -297,7 +300,7 @@ public static String lenientFormat(@NullableDecl String template, @NullableDecl
     return builder.toString();
   }
 
-  private static String lenientToString(@NullableDecl Object o) {
+  private static String lenientToString(@CheckForNull Object o) {
     if (o == null) {
       return "null";
     }
diff --git a/android/guava/src/com/google/common/base/Supplier.java b/android/guava/src/com/google/common/base/Supplier.java
index 662bf1f664df..f9e1e34f17a0 100644
--- a/android/guava/src/com/google/common/base/Supplier.java
+++ b/android/guava/src/com/google/common/base/Supplier.java
@@ -16,6 +16,7 @@
 
 import com.google.common.annotations.GwtCompatible;
 import com.google.errorprone.annotations.CanIgnoreReturnValue;
+import org.checkerframework.checker.nullness.qual.Nullable;
 
 /**
  * A class that can supply objects of a single type; a pre-Java-8 version of {@link
@@ -45,7 +46,8 @@
  * @since 2.0
  */
 @GwtCompatible
-public interface Supplier<T> {
+@ElementTypesAreNonnullByDefault
+public interface Supplier<T extends @Nullable Object> {
   /**
    * Retrieves an instance of the appropriate type. The returned object may or may not be a new
    * instance, depending on the implementation.
@@ -53,5 +55,6 @@ public interface Supplier<T> {
    * @return an instance of the appropriate type
    */
   @CanIgnoreReturnValue
+  @ParametricNullness
   T get();
 }
diff --git a/android/guava/src/com/google/common/base/Suppliers.java b/android/guava/src/com/google/common/base/Suppliers.java
index da1490da2d7c..6ced905b988d 100644
--- a/android/guava/src/com/google/common/base/Suppliers.java
+++ b/android/guava/src/com/google/common/base/Suppliers.java
@@ -14,14 +14,17 @@
 
 package com.google.common.base;
 
+import static com.google.common.base.NullnessCasts.uncheckedCastNullableTToT;
 import static com.google.common.base.Preconditions.checkArgument;
 import static com.google.common.base.Preconditions.checkNotNull;
+import static java.util.Objects.requireNonNull;
 
 import com.google.common.annotations.GwtCompatible;
 import com.google.common.annotations.VisibleForTesting;
 import java.io.Serializable;
 import java.util.concurrent.TimeUnit;
-import org.checkerframework.checker.nullness.compatqual.NullableDecl;
+import javax.annotation.CheckForNull;
+import org.checkerframework.checker.nullness.qual.Nullable;
 
 /**
  * Useful suppliers.
@@ -33,6 +36,7 @@
  * @since 2.0
  */
 @GwtCompatible
+@ElementTypesAreNonnullByDefault
 public final class Suppliers {
   private Suppliers() {}
 
@@ -42,11 +46,13 @@ private Suppliers() {}
    * and then applying {@code function} to that value. Note that the resulting supplier will not
    * call {@code supplier} or invoke {@code function} until it is called.
    */
-  public static <F, T> Supplier<T> compose(Function<? super F, T> function, Supplier<F> supplier) {
+  public static <F extends @Nullable Object, T extends @Nullable Object> Supplier<T> compose(
+      Function<? super F, T> function, Supplier<F> supplier) {
     return new SupplierComposition<>(function, supplier);
   }
 
-  private static class SupplierComposition<F, T> implements Supplier<T>, Serializable {
+  private static class SupplierComposition<F extends @Nullable Object, T extends @Nullable Object>
+      implements Supplier<T>, Serializable {
     final Function<? super F, T> function;
     final Supplier<F> supplier;
 
@@ -56,12 +62,13 @@ private static class SupplierComposition<F, T> implements Supplier<T>, Serializa
     }
 
     @Override
+    @ParametricNullness
     public T get() {
       return function.apply(supplier.get());
     }
 
     @Override
-    public boolean equals(@NullableDecl Object obj) {
+    public boolean equals(@CheckForNull Object obj) {
       if (obj instanceof SupplierComposition) {
         SupplierComposition<?, ?> that = (SupplierComposition<?, ?>) obj;
         return function.equals(that.function) && supplier.equals(that.supplier);
@@ -98,7 +105,7 @@ public String toString() {
    * <p>If {@code delegate} is an instance created by an earlier call to {@code memoize}, it is
    * returned directly.
    */
-  public static <T> Supplier<T> memoize(Supplier<T> delegate) {
+  public static <T extends @Nullable Object> Supplier<T> memoize(Supplier<T> delegate) {
     if (delegate instanceof NonSerializableMemoizingSupplier
         || delegate instanceof MemoizingSupplier) {
       return delegate;
@@ -109,18 +116,19 @@ public static <T> Supplier<T> memoize(Supplier<T> delegate) {
   }
 
   @VisibleForTesting
-  static class MemoizingSupplier<T> implements Supplier<T>, Serializable {
+  static class MemoizingSupplier<T extends @Nullable Object> implements Supplier<T>, Serializable {
     final Supplier<T> delegate;
     transient volatile boolean initialized;
     // "value" does not need to be volatile; visibility piggy-backs
     // on volatile read of "initialized".
-    @NullableDecl transient T value;
+    @CheckForNull transient T value;
 
     MemoizingSupplier(Supplier<T> delegate) {
       this.delegate = checkNotNull(delegate);
     }
 
     @Override
+    @ParametricNullness
     public T get() {
       // A 2-field variant of Double Checked Locking.
       if (!initialized) {
@@ -133,7 +141,8 @@ public T get() {
           }
         }
       }
-      return value;
+      // This is safe because we checked `initialized.`
+      return uncheckedCastNullableTToT(value);
     }
 
     @Override
@@ -147,24 +156,31 @@ public String toString() {
   }
 
   @VisibleForTesting
-  static class NonSerializableMemoizingSupplier<T> implements Supplier<T> {
-    volatile Supplier<T> delegate;
+  static class NonSerializableMemoizingSupplier<T extends @Nullable Object> implements Supplier<T> {
+    @CheckForNull volatile Supplier<T> delegate;
     volatile boolean initialized;
     // "value" does not need to be volatile; visibility piggy-backs
     // on volatile read of "initialized".
-    @NullableDecl T value;
+    @CheckForNull T value;
 
     NonSerializableMemoizingSupplier(Supplier<T> delegate) {
       this.delegate = checkNotNull(delegate);
     }
 
     @Override
+    @ParametricNullness
     public T get() {
       // A 2-field variant of Double Checked Locking.
       if (!initialized) {
         synchronized (this) {
           if (!initialized) {
-            T t = delegate.get();
+            /*
+             * requireNonNull is safe because we read and write `delegate` under synchronization.
+             *
+             * TODO(cpovirk): To avoid having to check for null, replace `delegate` with a singleton
+             * `Supplier` that always throws an exception.
+             */
+            T t = requireNonNull(delegate).get();
             value = t;
             initialized = true;
             // Release the delegate to GC.
@@ -173,7 +189,8 @@ public T get() {
           }
         }
       }
-      return value;
+      // This is safe because we checked `initialized.`
+      return uncheckedCastNullableTToT(value);
     }
 
     @Override
@@ -207,17 +224,18 @@ public String toString() {
    * @since 2.0
    */
   @SuppressWarnings("GoodTime") // should accept a java.time.Duration
-  public static <T> Supplier<T> memoizeWithExpiration(
+  public static <T extends @Nullable Object> Supplier<T> memoizeWithExpiration(
       Supplier<T> delegate, long duration, TimeUnit unit) {
-    return new ExpiringMemoizingSupplier<T>(delegate, duration, unit);
+    return new ExpiringMemoizingSupplier<>(delegate, duration, unit);
   }
 
   @VisibleForTesting
   @SuppressWarnings("GoodTime") // lots of violations
-  static class ExpiringMemoizingSupplier<T> implements Supplier<T>, Serializable {
+  static class ExpiringMemoizingSupplier<T extends @Nullable Object>
+      implements Supplier<T>, Serializable {
     final Supplier<T> delegate;
     final long durationNanos;
-    @NullableDecl transient volatile T value;
+    @CheckForNull transient volatile T value;
     // The special value 0 means "not yet initialized".
     transient volatile long expirationNanos;
 
@@ -228,6 +246,7 @@ static class ExpiringMemoizingSupplier<T> implements Supplier<T>, Serializable {
     }
 
     @Override
+    @ParametricNullness
     public T get() {
       // Another variant of Double Checked Locking.
       //
@@ -250,7 +269,8 @@ public T get() {
           }
         }
       }
-      return value;
+      // This is safe because we checked `expirationNanos.`
+      return uncheckedCastNullableTToT(value);
     }
 
     @Override
@@ -264,24 +284,27 @@ public String toString() {
   }
 
   /** Returns a supplier that always supplies {@code instance}. */
-  public static <T> Supplier<T> ofInstance(@NullableDecl T instance) {
-    return new SupplierOfInstance<T>(instance);
+  public static <T extends @Nullable Object> Supplier<T> ofInstance(
+      @ParametricNullness T instance) {
+    return new SupplierOfInstance<>(instance);
   }
 
-  private static class SupplierOfInstance<T> implements Supplier<T>, Serializable {
-    @NullableDecl final T instance;
+  private static class SupplierOfInstance<T extends @Nullable Object>
+      implements Supplier<T>, Serializable {
+    @ParametricNullness final T instance;
 
-    SupplierOfInstance(@NullableDecl T instance) {
+    SupplierOfInstance(@ParametricNullness T instance) {
       this.instance = instance;
     }
 
     @Override
+    @ParametricNullness
     public T get() {
       return instance;
     }
 
     @Override
-    public boolean equals(@NullableDecl Object obj) {
+    public boolean equals(@CheckForNull Object obj) {
       if (obj instanceof SupplierOfInstance) {
         SupplierOfInstance<?> that = (SupplierOfInstance<?>) obj;
         return Objects.equal(instance, that.instance);
@@ -306,11 +329,13 @@ public String toString() {
    * Returns a supplier whose {@code get()} method synchronizes on {@code delegate} before calling
    * it, making it thread-safe.
    */
-  public static <T> Supplier<T> synchronizedSupplier(Supplier<T> delegate) {
-    return new ThreadSafeSupplier<T>(delegate);
+  public static <T extends @Nullable Object> Supplier<T> synchronizedSupplier(
+      Supplier<T> delegate) {
+    return new ThreadSafeSupplier<>(delegate);
   }
 
-  private static class ThreadSafeSupplier<T> implements Supplier<T>, Serializable {
+  private static class ThreadSafeSupplier<T extends @Nullable Object>
+      implements Supplier<T>, Serializable {
     final Supplier<T> delegate;
 
     ThreadSafeSupplier(Supplier<T> delegate) {
@@ -318,6 +343,7 @@ private static class ThreadSafeSupplier<T> implements Supplier<T>, Serializable
     }
 
     @Override
+    @ParametricNullness
     public T get() {
       synchronized (delegate) {
         return delegate.get();
@@ -340,20 +366,21 @@ public String toString() {
    *
    * @since 8.0
    */
-  public static <T> Function<Supplier<T>, T> supplierFunction() {
+  public static <T extends @Nullable Object> Function<Supplier<T>, T> supplierFunction() {
     @SuppressWarnings("unchecked") // implementation is "fully variant"
     SupplierFunction<T> sf = (SupplierFunction<T>) SupplierFunctionImpl.INSTANCE;
     return sf;
   }
 
-  private interface SupplierFunction<T> extends Function<Supplier<T>, T> {}
+  private interface SupplierFunction<T extends @Nullable Object> extends Function<Supplier<T>, T> {}
 
-  private enum SupplierFunctionImpl implements SupplierFunction<Object> {
+  private enum SupplierFunctionImpl implements SupplierFunction<@Nullable Object> {
     INSTANCE;
 
     // Note: This makes T a "pass-through type"
     @Override
-    public Object apply(Supplier<Object> input) {
+    @CheckForNull
+    public Object apply(Supplier<@Nullable Object> input) {
       return input.get();
     }
 
diff --git a/android/guava/src/com/google/common/base/Throwables.java b/android/guava/src/com/google/common/base/Throwables.java
index b2abb504402f..e45ce800cb63 100644
--- a/android/guava/src/com/google/common/base/Throwables.java
+++ b/android/guava/src/com/google/common/base/Throwables.java
@@ -17,8 +17,8 @@
 import static com.google.common.base.Preconditions.checkNotNull;
 import static java.util.Arrays.asList;
 import static java.util.Collections.unmodifiableList;
+import static java.util.Objects.requireNonNull;
 
-import com.google.common.annotations.Beta;
 import com.google.common.annotations.GwtCompatible;
 import com.google.common.annotations.GwtIncompatible;
 import com.google.common.annotations.VisibleForTesting;
@@ -32,7 +32,7 @@
 import java.util.ArrayList;
 import java.util.Collections;
 import java.util.List;
-import org.checkerframework.checker.nullness.compatqual.NullableDecl;
+import javax.annotation.CheckForNull;
 
 /**
  * Static utility methods pertaining to instances of {@link Throwable}.
@@ -45,6 +45,7 @@
  * @since 1.0
  */
 @GwtCompatible(emulated = true)
+@ElementTypesAreNonnullByDefault
 public final class Throwables {
   private Throwables() {}
 
@@ -99,7 +100,7 @@ public static <X extends Throwable> void throwIfInstanceOf(
   @Deprecated
   @GwtIncompatible // throwIfInstanceOf
   public static <X extends Throwable> void propagateIfInstanceOf(
-      @NullableDecl Throwable throwable, Class<X> declaredType) throws X {
+      @CheckForNull Throwable throwable, Class<X> declaredType) throws X {
     if (throwable != null) {
       throwIfInstanceOf(throwable, declaredType);
     }
@@ -154,7 +155,7 @@ public static void throwIfUnchecked(Throwable throwable) {
    */
   @Deprecated
   @GwtIncompatible
-  public static void propagateIfPossible(@NullableDecl Throwable throwable) {
+  public static void propagateIfPossible(@CheckForNull Throwable throwable) {
     if (throwable != null) {
       throwIfUnchecked(throwable);
     }
@@ -180,7 +181,7 @@ public static void propagateIfPossible(@NullableDecl Throwable throwable) {
    */
   @GwtIncompatible // propagateIfInstanceOf
   public static <X extends Throwable> void propagateIfPossible(
-      @NullableDecl Throwable throwable, Class<X> declaredType) throws X {
+      @CheckForNull Throwable throwable, Class<X> declaredType) throws X {
     propagateIfInstanceOf(throwable, declaredType);
     propagateIfPossible(throwable);
   }
@@ -198,7 +199,7 @@ public static <X extends Throwable> void propagateIfPossible(
    */
   @GwtIncompatible // propagateIfInstanceOf
   public static <X1 extends Throwable, X2 extends Throwable> void propagateIfPossible(
-      @NullableDecl Throwable throwable, Class<X1> declaredType1, Class<X2> declaredType2)
+      @CheckForNull Throwable throwable, Class<X1> declaredType1, Class<X2> declaredType2)
       throws X1, X2 {
     checkNotNull(declaredType2);
     propagateIfInstanceOf(throwable, declaredType1);
@@ -288,7 +289,6 @@ public static Throwable getRootCause(Throwable throwable) {
    * @return an unmodifiable list containing the cause chain starting with {@code throwable}
    * @throws IllegalArgumentException if there is a loop in the causal chain
    */
-  @Beta // TODO(kevinb): decide best return type
   public static List<Throwable> getCausalChain(Throwable throwable) {
     checkNotNull(throwable);
     List<Throwable> causes = new ArrayList<>(4);
@@ -328,8 +328,8 @@ public static List<Throwable> getCausalChain(Throwable throwable) {
    *     ClassCastException}'s cause is {@code throwable}.
    * @since 22.0
    */
-  @Beta
   @GwtIncompatible // Class.cast(Object)
+  @CheckForNull
   public static <X extends Throwable> X getCauseAs(
       Throwable throwable, Class<X> expectedCauseType) {
     try {
@@ -379,11 +379,12 @@ public static String getStackTraceAsString(Throwable throwable) {
    * exception's creation.
    *
    * @since 19.0
+   * @deprecated This method is equivalent to {@link Throwable#getStackTrace()} on JDK versions past
+   *     JDK 8 and on all Android versions. Use {@link Throwable#getStackTrace()} directly, or where
+   *     possible use the {@code java.lang.StackWalker.walk} method introduced in JDK 9.
    */
-  // TODO(cpovirk): Say something about the possibility that List access could fail at runtime?
-  @Beta
+  @Deprecated
   @GwtIncompatible // lazyStackTraceIsLazy, jlaStackTrace
-  // TODO(cpovirk): Consider making this available under GWT (slow implementation only).
   public static List<StackTraceElement> lazyStackTrace(Throwable throwable) {
     return lazyStackTraceIsLazy()
         ? jlaStackTrace(throwable)
@@ -395,15 +396,17 @@ public static List<StackTraceElement> lazyStackTrace(Throwable throwable) {
    * documentation.
    *
    * @since 19.0
+   * @deprecated This method always returns false on JDK versions past JDK 8 and on all Android
+   *     versions.
    */
-  @Beta
+  @Deprecated
   @GwtIncompatible // getStackTraceElementMethod
   public static boolean lazyStackTraceIsLazy() {
     return getStackTraceElementMethod != null && getStackTraceDepthMethod != null;
   }
 
   @GwtIncompatible // invokeAccessibleNonThrowingMethod
-  private static List<StackTraceElement> jlaStackTrace(final Throwable t) {
+  private static List<StackTraceElement> jlaStackTrace(Throwable t) {
     checkNotNull(t);
     /*
      * TODO(cpovirk): Consider optimizing iterator() to catch IOOBE instead of doing bounds checks.
@@ -412,15 +415,22 @@ private static List<StackTraceElement> jlaStackTrace(final Throwable t) {
      * AOSP grief.
      */
     return new AbstractList<StackTraceElement>() {
+      /*
+       * The following requireNonNull calls are safe because we use jlaStackTrace() only if
+       * lazyStackTraceIsLazy() returns true.
+       */
       @Override
       public StackTraceElement get(int n) {
         return (StackTraceElement)
-            invokeAccessibleNonThrowingMethod(getStackTraceElementMethod, jla, t, n);
+            invokeAccessibleNonThrowingMethod(
+                requireNonNull(getStackTraceElementMethod), requireNonNull(jla), t, n);
       }
 
       @Override
       public int size() {
-        return (Integer) invokeAccessibleNonThrowingMethod(getStackTraceDepthMethod, jla, t);
+        return (Integer)
+            invokeAccessibleNonThrowingMethod(
+                requireNonNull(getStackTraceDepthMethod), requireNonNull(jla), t);
       }
     };
   }
@@ -448,7 +458,7 @@ private static Object invokeAccessibleNonThrowingMethod(
 
   /** Access to some fancy internal JVM internals. */
   @GwtIncompatible // java.lang.reflect
-  @NullableDecl
+  @CheckForNull
   private static final Object jla = getJLA();
 
   /**
@@ -456,7 +466,7 @@ private static Object invokeAccessibleNonThrowingMethod(
    * find it when available. When this is null, use the slow way.
    */
   @GwtIncompatible // java.lang.reflect
-  @NullableDecl
+  @CheckForNull
   private static final Method getStackTraceElementMethod = (jla == null) ? null : getGetMethod();
 
   /**
@@ -464,15 +474,15 @@ private static Object invokeAccessibleNonThrowingMethod(
    * when available. When this is null, use the slow way.
    */
   @GwtIncompatible // java.lang.reflect
-  @NullableDecl
-  private static final Method getStackTraceDepthMethod = (jla == null) ? null : getSizeMethod();
+  @CheckForNull
+  private static final Method getStackTraceDepthMethod = (jla == null) ? null : getSizeMethod(jla);
 
   /**
    * Returns the JavaLangAccess class that is present in all Sun JDKs. It is not allowed in
    * AppEngine, and not present in non-Sun JDKs.
    */
   @GwtIncompatible // java.lang.reflect
-  @NullableDecl
+  @CheckForNull
   private static Object getJLA() {
     try {
       /*
@@ -498,7 +508,7 @@ private static Object getJLA() {
    * method cannot be found (it is only to be found in fairly recent JDKs).
    */
   @GwtIncompatible // java.lang.reflect
-  @NullableDecl
+  @CheckForNull
   private static Method getGetMethod() {
     return getJlaMethod("getStackTraceElement", Throwable.class, int.class);
   }
@@ -513,14 +523,14 @@ private static Method getGetMethod() {
    * UnsupportedOperationException</a>.
    */
   @GwtIncompatible // java.lang.reflect
-  @NullableDecl
-  private static Method getSizeMethod() {
+  @CheckForNull
+  private static Method getSizeMethod(Object jla) {
     try {
       Method getStackTraceDepth = getJlaMethod("getStackTraceDepth", Throwable.class);
       if (getStackTraceDepth == null) {
         return null;
       }
-      getStackTraceDepth.invoke(getJLA(), new Throwable());
+      getStackTraceDepth.invoke(jla, new Throwable());
       return getStackTraceDepth;
     } catch (UnsupportedOperationException | IllegalAccessException | InvocationTargetException e) {
       return null;
@@ -528,7 +538,7 @@ private static Method getSizeMethod() {
   }
 
   @GwtIncompatible // java.lang.reflect
-  @NullableDecl
+  @CheckForNull
   private static Method getJlaMethod(String name, Class<?>... parameterTypes) throws ThreadDeath {
     try {
       return Class.forName(JAVA_LANG_ACCESS_CLASSNAME, false, null).getMethod(name, parameterTypes);
diff --git a/android/guava/src/com/google/common/base/Ticker.java b/android/guava/src/com/google/common/base/Ticker.java
index a53883b46ed7..d898735c028f 100644
--- a/android/guava/src/com/google/common/base/Ticker.java
+++ b/android/guava/src/com/google/common/base/Ticker.java
@@ -28,6 +28,7 @@
  *     source-compatible</a> since 9.0)
  */
 @GwtCompatible
+@ElementTypesAreNonnullByDefault
 public abstract class Ticker {
   /** Constructor for use by subclasses. */
   protected Ticker() {}
diff --git a/android/guava/src/com/google/common/base/Utf8.java b/android/guava/src/com/google/common/base/Utf8.java
index 8a2fbb743cf3..bb945a35f095 100644
--- a/android/guava/src/com/google/common/base/Utf8.java
+++ b/android/guava/src/com/google/common/base/Utf8.java
@@ -38,6 +38,7 @@
  */
 @Beta
 @GwtCompatible(emulated = true)
+@ElementTypesAreNonnullByDefault
 public final class Utf8 {
   /**
    * Returns the number of bytes in the UTF-8-encoded form of {@code sequence}. For a string, this
diff --git a/android/guava/src/com/google/common/base/Verify.java b/android/guava/src/com/google/common/base/Verify.java
index 843a77fe91f0..b2e9f5f04faf 100644
--- a/android/guava/src/com/google/common/base/Verify.java
+++ b/android/guava/src/com/google/common/base/Verify.java
@@ -18,7 +18,8 @@
 
 import com.google.common.annotations.GwtCompatible;
 import com.google.errorprone.annotations.CanIgnoreReturnValue;
-import org.checkerframework.checker.nullness.compatqual.NullableDecl;
+import javax.annotation.CheckForNull;
+import org.checkerframework.checker.nullness.qual.Nullable;
 
 /**
  * Static convenience methods that serve the same purpose as Java language <a
@@ -87,6 +88,7 @@
  * @since 17.0
  */
 @GwtCompatible
+@ElementTypesAreNonnullByDefault
 public final class Verify {
   /**
    * Ensures that {@code expression} is {@code true}, throwing a {@code VerifyException} with no
@@ -118,8 +120,8 @@ public static void verify(boolean expression) {
    */
   public static void verify(
       boolean expression,
-      @NullableDecl String errorMessageTemplate,
-      @NullableDecl Object... errorMessageArgs) {
+      String errorMessageTemplate,
+      @CheckForNull @Nullable Object... errorMessageArgs) {
     if (!expression) {
       throw new VerifyException(lenientFormat(errorMessageTemplate, errorMessageArgs));
     }
@@ -133,8 +135,7 @@ public static void verify(
    *
    * @since 23.1 (varargs overload since 17.0)
    */
-  public static void verify(
-      boolean expression, @NullableDecl String errorMessageTemplate, char p1) {
+  public static void verify(boolean expression, String errorMessageTemplate, char p1) {
     if (!expression) {
       throw new VerifyException(lenientFormat(errorMessageTemplate, p1));
     }
@@ -148,7 +149,7 @@ public static void verify(
    *
    * @since 23.1 (varargs overload since 17.0)
    */
-  public static void verify(boolean expression, @NullableDecl String errorMessageTemplate, int p1) {
+  public static void verify(boolean expression, String errorMessageTemplate, int p1) {
     if (!expression) {
       throw new VerifyException(lenientFormat(errorMessageTemplate, p1));
     }
@@ -162,8 +163,7 @@ public static void verify(boolean expression, @NullableDecl String errorMessageT
    *
    * @since 23.1 (varargs overload since 17.0)
    */
-  public static void verify(
-      boolean expression, @NullableDecl String errorMessageTemplate, long p1) {
+  public static void verify(boolean expression, String errorMessageTemplate, long p1) {
     if (!expression) {
       throw new VerifyException(lenientFormat(errorMessageTemplate, p1));
     }
@@ -178,7 +178,7 @@ public static void verify(
    * @since 23.1 (varargs overload since 17.0)
    */
   public static void verify(
-      boolean expression, @NullableDecl String errorMessageTemplate, @NullableDecl Object p1) {
+      boolean expression, String errorMessageTemplate, @CheckForNull Object p1) {
     if (!expression) {
       throw new VerifyException(lenientFormat(errorMessageTemplate, p1));
     }
@@ -192,8 +192,7 @@ public static void verify(
    *
    * @since 23.1 (varargs overload since 17.0)
    */
-  public static void verify(
-      boolean expression, @NullableDecl String errorMessageTemplate, char p1, char p2) {
+  public static void verify(boolean expression, String errorMessageTemplate, char p1, char p2) {
     if (!expression) {
       throw new VerifyException(lenientFormat(errorMessageTemplate, p1, p2));
     }
@@ -207,8 +206,7 @@ public static void verify(
    *
    * @since 23.1 (varargs overload since 17.0)
    */
-  public static void verify(
-      boolean expression, @NullableDecl String errorMessageTemplate, int p1, char p2) {
+  public static void verify(boolean expression, String errorMessageTemplate, int p1, char p2) {
     if (!expression) {
       throw new VerifyException(lenientFormat(errorMessageTemplate, p1, p2));
     }
@@ -222,8 +220,7 @@ public static void verify(
    *
    * @since 23.1 (varargs overload since 17.0)
    */
-  public static void verify(
-      boolean expression, @NullableDecl String errorMessageTemplate, long p1, char p2) {
+  public static void verify(boolean expression, String errorMessageTemplate, long p1, char p2) {
     if (!expression) {
       throw new VerifyException(lenientFormat(errorMessageTemplate, p1, p2));
     }
@@ -238,10 +235,7 @@ public static void verify(
    * @since 23.1 (varargs overload since 17.0)
    */
   public static void verify(
-      boolean expression,
-      @NullableDecl String errorMessageTemplate,
-      @NullableDecl Object p1,
-      char p2) {
+      boolean expression, String errorMessageTemplate, @CheckForNull Object p1, char p2) {
     if (!expression) {
       throw new VerifyException(lenientFormat(errorMessageTemplate, p1, p2));
     }
@@ -255,8 +249,7 @@ public static void verify(
    *
    * @since 23.1 (varargs overload since 17.0)
    */
-  public static void verify(
-      boolean expression, @NullableDecl String errorMessageTemplate, char p1, int p2) {
+  public static void verify(boolean expression, String errorMessageTemplate, char p1, int p2) {
     if (!expression) {
       throw new VerifyException(lenientFormat(errorMessageTemplate, p1, p2));
     }
@@ -270,8 +263,7 @@ public static void verify(
    *
    * @since 23.1 (varargs overload since 17.0)
    */
-  public static void verify(
-      boolean expression, @NullableDecl String errorMessageTemplate, int p1, int p2) {
+  public static void verify(boolean expression, String errorMessageTemplate, int p1, int p2) {
     if (!expression) {
       throw new VerifyException(lenientFormat(errorMessageTemplate, p1, p2));
     }
@@ -285,8 +277,7 @@ public static void verify(
    *
    * @since 23.1 (varargs overload since 17.0)
    */
-  public static void verify(
-      boolean expression, @NullableDecl String errorMessageTemplate, long p1, int p2) {
+  public static void verify(boolean expression, String errorMessageTemplate, long p1, int p2) {
     if (!expression) {
       throw new VerifyException(lenientFormat(errorMessageTemplate, p1, p2));
     }
@@ -301,10 +292,7 @@ public static void verify(
    * @since 23.1 (varargs overload since 17.0)
    */
   public static void verify(
-      boolean expression,
-      @NullableDecl String errorMessageTemplate,
-      @NullableDecl Object p1,
-      int p2) {
+      boolean expression, String errorMessageTemplate, @CheckForNull Object p1, int p2) {
     if (!expression) {
       throw new VerifyException(lenientFormat(errorMessageTemplate, p1, p2));
     }
@@ -318,8 +306,7 @@ public static void verify(
    *
    * @since 23.1 (varargs overload since 17.0)
    */
-  public static void verify(
-      boolean expression, @NullableDecl String errorMessageTemplate, char p1, long p2) {
+  public static void verify(boolean expression, String errorMessageTemplate, char p1, long p2) {
     if (!expression) {
       throw new VerifyException(lenientFormat(errorMessageTemplate, p1, p2));
     }
@@ -333,8 +320,7 @@ public static void verify(
    *
    * @since 23.1 (varargs overload since 17.0)
    */
-  public static void verify(
-      boolean expression, @NullableDecl String errorMessageTemplate, int p1, long p2) {
+  public static void verify(boolean expression, String errorMessageTemplate, int p1, long p2) {
     if (!expression) {
       throw new VerifyException(lenientFormat(errorMessageTemplate, p1, p2));
     }
@@ -348,8 +334,7 @@ public static void verify(
    *
    * @since 23.1 (varargs overload since 17.0)
    */
-  public static void verify(
-      boolean expression, @NullableDecl String errorMessageTemplate, long p1, long p2) {
+  public static void verify(boolean expression, String errorMessageTemplate, long p1, long p2) {
     if (!expression) {
       throw new VerifyException(lenientFormat(errorMessageTemplate, p1, p2));
     }
@@ -364,10 +349,7 @@ public static void verify(
    * @since 23.1 (varargs overload since 17.0)
    */
   public static void verify(
-      boolean expression,
-      @NullableDecl String errorMessageTemplate,
-      @NullableDecl Object p1,
-      long p2) {
+      boolean expression, String errorMessageTemplate, @CheckForNull Object p1, long p2) {
     if (!expression) {
       throw new VerifyException(lenientFormat(errorMessageTemplate, p1, p2));
     }
@@ -382,10 +364,7 @@ public static void verify(
    * @since 23.1 (varargs overload since 17.0)
    */
   public static void verify(
-      boolean expression,
-      @NullableDecl String errorMessageTemplate,
-      char p1,
-      @NullableDecl Object p2) {
+      boolean expression, String errorMessageTemplate, char p1, @CheckForNull Object p2) {
     if (!expression) {
       throw new VerifyException(lenientFormat(errorMessageTemplate, p1, p2));
     }
@@ -400,10 +379,7 @@ public static void verify(
    * @since 23.1 (varargs overload since 17.0)
    */
   public static void verify(
-      boolean expression,
-      @NullableDecl String errorMessageTemplate,
-      int p1,
-      @NullableDecl Object p2) {
+      boolean expression, String errorMessageTemplate, int p1, @CheckForNull Object p2) {
     if (!expression) {
       throw new VerifyException(lenientFormat(errorMessageTemplate, p1, p2));
     }
@@ -418,10 +394,7 @@ public static void verify(
    * @since 23.1 (varargs overload since 17.0)
    */
   public static void verify(
-      boolean expression,
-      @NullableDecl String errorMessageTemplate,
-      long p1,
-      @NullableDecl Object p2) {
+      boolean expression, String errorMessageTemplate, long p1, @CheckForNull Object p2) {
     if (!expression) {
       throw new VerifyException(lenientFormat(errorMessageTemplate, p1, p2));
     }
@@ -437,9 +410,9 @@ public static void verify(
    */
   public static void verify(
       boolean expression,
-      @NullableDecl String errorMessageTemplate,
-      @NullableDecl Object p1,
-      @NullableDecl Object p2) {
+      String errorMessageTemplate,
+      @CheckForNull Object p1,
+      @CheckForNull Object p2) {
     if (!expression) {
       throw new VerifyException(lenientFormat(errorMessageTemplate, p1, p2));
     }
@@ -455,10 +428,10 @@ public static void verify(
    */
   public static void verify(
       boolean expression,
-      @NullableDecl String errorMessageTemplate,
-      @NullableDecl Object p1,
-      @NullableDecl Object p2,
-      @NullableDecl Object p3) {
+      String errorMessageTemplate,
+      @CheckForNull Object p1,
+      @CheckForNull Object p2,
+      @CheckForNull Object p3) {
     if (!expression) {
       throw new VerifyException(lenientFormat(errorMessageTemplate, p1, p2, p3));
     }
@@ -474,16 +447,25 @@ public static void verify(
    */
   public static void verify(
       boolean expression,
-      @NullableDecl String errorMessageTemplate,
-      @NullableDecl Object p1,
-      @NullableDecl Object p2,
-      @NullableDecl Object p3,
-      @NullableDecl Object p4) {
+      String errorMessageTemplate,
+      @CheckForNull Object p1,
+      @CheckForNull Object p2,
+      @CheckForNull Object p3,
+      @CheckForNull Object p4) {
     if (!expression) {
       throw new VerifyException(lenientFormat(errorMessageTemplate, p1, p2, p3, p4));
     }
   }
 
+  /*
+   * For a discussion of the signature of verifyNotNull, see the discussion above
+   * Preconditions.checkNotNull.
+   *
+   * (verifyNotNull has many fewer "problem" callers, so we could try to be stricter. On the other
+   * hand, verifyNotNull arguably has more reason to accept nullable arguments in the first
+   * place....)
+   */
+
   /**
    * Ensures that {@code reference} is non-null, throwing a {@code VerifyException} with a default
    * message otherwise.
@@ -493,7 +475,7 @@ public static void verify(
    * @see Preconditions#checkNotNull Preconditions.checkNotNull()
    */
   @CanIgnoreReturnValue
-  public static <T> T verifyNotNull(@NullableDecl T reference) {
+  public static <T> T verifyNotNull(@CheckForNull T reference) {
     return verifyNotNull(reference, "expected a non-null reference");
   }
 
@@ -514,10 +496,12 @@ public static <T> T verifyNotNull(@NullableDecl T reference) {
    */
   @CanIgnoreReturnValue
   public static <T> T verifyNotNull(
-      @NullableDecl T reference,
-      @NullableDecl String errorMessageTemplate,
-      @NullableDecl Object... errorMessageArgs) {
-    verify(reference != null, errorMessageTemplate, errorMessageArgs);
+      @CheckForNull T reference,
+      String errorMessageTemplate,
+      @CheckForNull @Nullable Object... errorMessageArgs) {
+    if (reference == null) {
+      throw new VerifyException(lenientFormat(errorMessageTemplate, errorMessageArgs));
+    }
     return reference;
   }
 
diff --git a/android/guava/src/com/google/common/base/VerifyException.java b/android/guava/src/com/google/common/base/VerifyException.java
index eed5c6df2996..10b99dee722b 100644
--- a/android/guava/src/com/google/common/base/VerifyException.java
+++ b/android/guava/src/com/google/common/base/VerifyException.java
@@ -15,7 +15,7 @@
 package com.google.common.base;
 
 import com.google.common.annotations.GwtCompatible;
-import org.checkerframework.checker.nullness.compatqual.NullableDecl;
+import javax.annotation.CheckForNull;
 
 /**
  * Exception thrown upon the failure of a <a
@@ -25,12 +25,13 @@
  * @since 17.0
  */
 @GwtCompatible
+@ElementTypesAreNonnullByDefault
 public class VerifyException extends RuntimeException {
   /** Constructs a {@code VerifyException} with no message. */
   public VerifyException() {}
 
   /** Constructs a {@code VerifyException} with the message {@code message}. */
-  public VerifyException(@NullableDecl String message) {
+  public VerifyException(@CheckForNull String message) {
     super(message);
   }
 
@@ -40,7 +41,7 @@ public VerifyException(@NullableDecl String message) {
    *
    * @since 19.0
    */
-  public VerifyException(@NullableDecl Throwable cause) {
+  public VerifyException(@CheckForNull Throwable cause) {
     super(cause);
   }
 
@@ -50,7 +51,7 @@ public VerifyException(@NullableDecl Throwable cause) {
    *
    * @since 19.0
    */
-  public VerifyException(@NullableDecl String message, @NullableDecl Throwable cause) {
+  public VerifyException(@CheckForNull String message, @CheckForNull Throwable cause) {
     super(message, cause);
   }
 }
diff --git a/android/guava/src/com/google/common/base/internal/Finalizer.java b/android/guava/src/com/google/common/base/internal/Finalizer.java
index 0da22069e338..b45ec157879d 100644
--- a/android/guava/src/com/google/common/base/internal/Finalizer.java
+++ b/android/guava/src/com/google/common/base/internal/Finalizer.java
@@ -23,7 +23,7 @@
 import java.lang.reflect.Method;
 import java.util.logging.Level;
 import java.util.logging.Logger;
-import org.checkerframework.checker.nullness.compatqual.NullableDecl;
+import javax.annotation.CheckForNull;
 
 /**
  * Thread that finalizes referents. All references should implement {@code
@@ -43,6 +43,7 @@
  * collected, and this class can detect when the main class loader has been garbage collected and
  * stop itself.
  */
+// no @ElementTypesAreNonNullByDefault for the reasons discussed above
 public class Finalizer implements Runnable {
 
   private static final Logger logger = Logger.getLogger(Finalizer.class.getName());
@@ -116,10 +117,10 @@ public static void startFinalizer(
   // By preference, we will use the Thread constructor that has an `inheritThreadLocals` parameter.
   // But before Java 9, our only way not to inherit ThreadLocals is to zap them after the thread
   // is created, by accessing a private field.
-  @NullableDecl
+  @CheckForNull
   private static final Constructor<Thread> bigThreadConstructor = getBigThreadConstructor();
 
-  @NullableDecl
+  @CheckForNull
   private static final Field inheritableThreadLocals =
       (bigThreadConstructor == null) ? getInheritableThreadLocalsField() : null;
 
@@ -130,8 +131,7 @@ private Finalizer(
       PhantomReference<Object> frqReference) {
     this.queue = queue;
 
-    this.finalizableReferenceClassReference =
-        new WeakReference<Class<?>>(finalizableReferenceClass);
+    this.finalizableReferenceClassReference = new WeakReference<>(finalizableReferenceClass);
 
     // Keep track of the FRQ that started us so we know when to stop.
     this.frqReference = frqReference;
@@ -192,7 +192,7 @@ private boolean cleanUp(Reference<?> reference) {
   }
 
   /** Looks up FinalizableReference.finalizeReferent() method. */
-  @NullableDecl
+  @CheckForNull
   private Method getFinalizeReferentMethod() {
     Class<?> finalizableReferenceClass = finalizableReferenceClassReference.get();
     if (finalizableReferenceClass == null) {
@@ -211,7 +211,7 @@ private Method getFinalizeReferentMethod() {
     }
   }
 
-  @NullableDecl
+  @CheckForNull
   private static Field getInheritableThreadLocalsField() {
     try {
       Field inheritableThreadLocals = Thread.class.getDeclaredField("inheritableThreadLocals");
@@ -226,7 +226,7 @@ private static Field getInheritableThreadLocalsField() {
     }
   }
 
-  @NullableDecl
+  @CheckForNull
   private static Constructor<Thread> getBigThreadConstructor() {
     try {
       return Thread.class.getConstructor(
diff --git a/android/guava/src/com/google/common/cache/AbstractCache.java b/android/guava/src/com/google/common/cache/AbstractCache.java
index d8ef0323a81d..eec5fdc34f56 100644
--- a/android/guava/src/com/google/common/cache/AbstractCache.java
+++ b/android/guava/src/com/google/common/cache/AbstractCache.java
@@ -38,6 +38,7 @@
  * @since 10.0
  */
 @GwtCompatible
+@ElementTypesAreNonnullByDefault
 public abstract class AbstractCache<K, V> implements Cache<K, V> {
 
   /** Constructor for use by subclasses. */
@@ -58,8 +59,12 @@ public V get(K key, Callable<? extends V> valueLoader) throws ExecutionException
    *
    * @since 11.0
    */
+  /*
+   * <? extends Object> is mostly the same as <?> to plain Java. But to nullness checkers, they
+   * differ: <? extends Object> means "non-null types," while <?> means "all types."
+   */
   @Override
-  public ImmutableMap<K, V> getAllPresent(Iterable<?> keys) {
+  public ImmutableMap<K, V> getAllPresent(Iterable<? extends Object> keys) {
     Map<K, V> result = Maps.newLinkedHashMap();
     for (Object key : keys) {
       if (!result.containsKey(key)) {
@@ -103,7 +108,8 @@ public void invalidate(Object key) {
 
   /** @since 11.0 */
   @Override
-  public void invalidateAll(Iterable<?> keys) {
+  // For discussion of <? extends Object>, see getAllPresent.
+  public void invalidateAll(Iterable<? extends Object> keys) {
     for (Object key : keys) {
       invalidate(key);
     }
diff --git a/android/guava/src/com/google/common/cache/AbstractLoadingCache.java b/android/guava/src/com/google/common/cache/AbstractLoadingCache.java
index 38b97747915e..489597c51843 100644
--- a/android/guava/src/com/google/common/cache/AbstractLoadingCache.java
+++ b/android/guava/src/com/google/common/cache/AbstractLoadingCache.java
@@ -38,6 +38,7 @@
  * @since 11.0
  */
 @GwtIncompatible
+@ElementTypesAreNonnullByDefault
 public abstract class AbstractLoadingCache<K, V> extends AbstractCache<K, V>
     implements LoadingCache<K, V> {
 
diff --git a/android/guava/src/com/google/common/cache/Cache.java b/android/guava/src/com/google/common/cache/Cache.java
index a47c4fe47b3e..1234bb6a3e96 100644
--- a/android/guava/src/com/google/common/cache/Cache.java
+++ b/android/guava/src/com/google/common/cache/Cache.java
@@ -25,7 +25,7 @@
 import java.util.concurrent.Callable;
 import java.util.concurrent.ConcurrentMap;
 import java.util.concurrent.ExecutionException;
-import org.checkerframework.checker.nullness.compatqual.NullableDecl;
+import javax.annotation.CheckForNull;
 
 /**
  * A semi-persistent mapping from keys to values. Cache entries are manually added using {@link
@@ -35,11 +35,14 @@
  * <p>Implementations of this interface are expected to be thread-safe, and can be safely accessed
  * by multiple concurrent threads.
  *
+ * @param <K> the type of the cache's keys, which are not permitted to be null
+ * @param <V> the type of the cache's values, which are not permitted to be null
  * @author Charles Fry
  * @since 10.0
  */
 @DoNotMock("Use CacheBuilder.newBuilder().build()")
 @GwtCompatible
+@ElementTypesAreNonnullByDefault
 public interface Cache<K, V> {
 
   /**
@@ -48,7 +51,7 @@ public interface Cache<K, V> {
    *
    * @since 11.0
    */
-  @NullableDecl
+  @CheckForNull
   V getIfPresent(@CompatibleWith("K") Object key);
 
   /**
@@ -105,7 +108,11 @@ public interface Cache<K, V> {
    *
    * @since 11.0
    */
-  ImmutableMap<K, V> getAllPresent(Iterable<?> keys);
+  /*
+   * <? extends Object> is mostly the same as <?> to plain Java. But to nullness checkers, they
+   * differ: <? extends Object> means "non-null types," while <?> means "all types."
+   */
+  ImmutableMap<K, V> getAllPresent(Iterable<? extends Object> keys);
 
   /**
    * Associates {@code value} with {@code key} in this cache. If the cache previously contained a
@@ -136,7 +143,8 @@ public interface Cache<K, V> {
    *
    * @since 11.0
    */
-  void invalidateAll(Iterable<?> keys);
+  // For discussion of <? extends Object>, see getAllPresent.
+  void invalidateAll(Iterable<? extends Object> keys);
 
   /** Discards all entries in the cache. */
   void invalidateAll();
diff --git a/android/guava/src/com/google/common/cache/CacheBuilder.java b/android/guava/src/com/google/common/cache/CacheBuilder.java
index c46779b5a926..b690973b2505 100644
--- a/android/guava/src/com/google/common/cache/CacheBuilder.java
+++ b/android/guava/src/com/google/common/cache/CacheBuilder.java
@@ -39,15 +39,57 @@
 import java.util.concurrent.TimeUnit;
 import java.util.logging.Level;
 import java.util.logging.Logger;
-import org.checkerframework.checker.nullness.compatqual.NullableDecl;
+import org.checkerframework.checker.nullness.qual.Nullable;
 
 /**
- * A builder of {@link LoadingCache} and {@link Cache} instances having any combination of the
- * following features:
+ * A builder of {@link LoadingCache} and {@link Cache} instances.
+ *
+ * <h2>Prefer <a href="https://github.com/ben-manes/caffeine/wiki">Caffeine</a> over Guava's caching
+ * API</h2>
+ *
+ * <p>The successor to Guava's caching API is <a
+ * href="https://github.com/ben-manes/caffeine/wiki">Caffeine</a>. Its API is designed to make it a
+ * nearly drop-in replacement -- though it requires Java 8 APIs, is not available for Android or
+ * GWT/j2cl, and may have <a href="https://github.com/ben-manes/caffeine/wiki/Guava">different
+ * (usually better) behavior</a> when multiple threads attempt concurrent mutations. Its equivalent
+ * to {@code CacheBuilder} is its <a
+ * href="https://www.javadoc.io/doc/com.github.ben-manes.caffeine/caffeine/latest/com.github.benmanes.caffeine/com/github/benmanes/caffeine/cache/Caffeine.html">{@code
+ * Caffeine}</a> class. Caffeine offers better performance, more features (including asynchronous
+ * loading), and fewer <a
+ * href="https://github.com/google/guava/issues?q=is%3Aopen+is%3Aissue+label%3Apackage%3Dcache+label%3Atype%3Ddefect">bugs</a>.
+ *
+ * <p>Caffeine defines its own interfaces (<a
+ * href="https://www.javadoc.io/doc/com.github.ben-manes.caffeine/caffeine/latest/com.github.benmanes.caffeine/com/github/benmanes/caffeine/cache/Cache.html">{@code
+ * Cache}</a>, <a
+ * href="https://www.javadoc.io/doc/com.github.ben-manes.caffeine/caffeine/latest/com.github.benmanes.caffeine/com/github/benmanes/caffeine/cache/LoadingCache.html">{@code
+ * LoadingCache}</a>, <a
+ * href="https://www.javadoc.io/doc/com.github.ben-manes.caffeine/caffeine/latest/com.github.benmanes.caffeine/com/github/benmanes/caffeine/cache/CacheLoader.html">{@code
+ * CacheLoader}</a>, etc.), so you can use Caffeine without needing to use any Guava types.
+ * Caffeine's types are better than Guava's, especially for <a
+ * href="https://www.javadoc.io/doc/com.github.ben-manes.caffeine/caffeine/latest/com.github.benmanes.caffeine/com/github/benmanes/caffeine/cache/AsyncLoadingCache.html">their
+ * deep support for asynchronous operations</a>. But if you want to migrate to Caffeine with minimal
+ * code changes, you can use <a
+ * href="https://www.javadoc.io/doc/com.github.ben-manes.caffeine/guava/latest/com.github.benmanes.caffeine.guava/com/github/benmanes/caffeine/guava/CaffeinatedGuava.html">its
+ * {@code CaffeinatedGuava} adapter class</a>, which lets you build a Guava {@code Cache} or a Guava
+ * {@code LoadingCache} backed by a Guava {@code CacheLoader}.
+ *
+ * <p>Caffeine's API for asynchronous operations uses {@code CompletableFuture}: <a
+ * href="https://www.javadoc.io/doc/com.github.ben-manes.caffeine/caffeine/latest/com.github.benmanes.caffeine/com/github/benmanes/caffeine/cache/AsyncLoadingCache.html#get(K)">{@code
+ * AsyncLoadingCache.get}</a> returns a {@code CompletableFuture}, and implementations of <a
+ * href="https://www.javadoc.io/doc/com.github.ben-manes.caffeine/caffeine/latest/com.github.benmanes.caffeine/com/github/benmanes/caffeine/cache/AsyncCacheLoader.html#asyncLoad(K,java.util.concurrent.Executor)">{@code
+ * AsyncCacheLoader.asyncLoad}</a> must return a {@code CompletableFuture}. Users of Guava's {@link
+ * com.google.common.util.concurrent.ListenableFuture} can adapt between the two {@code Future}
+ * types by using <a href="https://github.com/lukas-krecan/future-converter#java8-guava">{@code
+ * net.javacrumbs.futureconverter.java8guava.FutureConverter}</a>.
+ *
+ * <h2>More on {@code CacheBuilder}</h2>
+ *
+ * {@code CacheBuilder} builds caches with any combination of the following features:
  *
  * <ul>
  *   <li>automatic loading of entries into the cache
- *   <li>least-recently-used eviction when a maximum size is exceeded
+ *   <li>least-recently-used eviction when a maximum size is exceeded (note that the cache is
+ *       divided into segments, each of which does LRU internally)
  *   <li>time-based expiration of entries, measured since last access or last write
  *   <li>keys automatically wrapped in {@code WeakReference}
  *   <li>values automatically wrapped in {@code WeakReference} or {@code SoftReference}
@@ -142,15 +184,16 @@
  *
  * @param <K> the most general key type this builder will be able to create caches for. This is
  *     normally {@code Object} unless it is constrained by using a method like {@code
- *     #removalListener}
+ *     #removalListener}. Cache keys may not be null.
  * @param <V> the most general value type this builder will be able to create caches for. This is
  *     normally {@code Object} unless it is constrained by using a method like {@code
- *     #removalListener}
+ *     #removalListener}. Cache values may not be null.
  * @author Charles Fry
  * @author Kevin Bourrillion
  * @since 10.0
  */
 @GwtCompatible(emulated = true)
+@ElementTypesAreNonnullByDefault
 public final class CacheBuilder<K, V> {
   private static final int DEFAULT_INITIAL_CAPACITY = 16;
   private static final int DEFAULT_CONCURRENCY_LEVEL = 4;
@@ -230,10 +273,10 @@ public long read() {
   int concurrencyLevel = UNSET_INT;
   long maximumSize = UNSET_INT;
   long maximumWeight = UNSET_INT;
-  @NullableDecl Weigher<? super K, ? super V> weigher;
+  @Nullable Weigher<? super K, ? super V> weigher;
 
-  @NullableDecl Strength keyStrength;
-  @NullableDecl Strength valueStrength;
+  @Nullable Strength keyStrength;
+  @Nullable Strength valueStrength;
 
   @SuppressWarnings("GoodTime") // should be a java.time.Duration
   long expireAfterWriteNanos = UNSET_INT;
@@ -244,11 +287,11 @@ public long read() {
   @SuppressWarnings("GoodTime") // should be a java.time.Duration
   long refreshNanos = UNSET_INT;
 
-  @NullableDecl Equivalence<Object> keyEquivalence;
-  @NullableDecl Equivalence<Object> valueEquivalence;
+  @Nullable Equivalence<Object> keyEquivalence;
+  @Nullable Equivalence<Object> valueEquivalence;
 
-  @NullableDecl RemovalListener<? super K, ? super V> removalListener;
-  @NullableDecl Ticker ticker;
+  @Nullable RemovalListener<? super K, ? super V> removalListener;
+  @Nullable Ticker ticker;
 
   Supplier<? extends StatsCounter> statsCounterSupplier = NULL_STATS_COUNTER;
 
@@ -650,7 +693,7 @@ Strength getValueStrength() {
    * @param unit the unit that {@code duration} is expressed in
    * @return this {@code CacheBuilder} instance (for chaining)
    * @throws IllegalArgumentException if {@code duration} is negative
-   * @throws IllegalStateException if the time to live or time to idle was already set
+   * @throws IllegalStateException if {@link #expireAfterWrite} was already set
    */
   @SuppressWarnings("GoodTime") // should accept a java.time.Duration
   public CacheBuilder<K, V> expireAfterWrite(long duration, TimeUnit unit) {
@@ -690,7 +733,7 @@ long getExpireAfterWriteNanos() {
    * @param unit the unit that {@code duration} is expressed in
    * @return this {@code CacheBuilder} instance (for chaining)
    * @throws IllegalArgumentException if {@code duration} is negative
-   * @throws IllegalStateException if the time to idle or time to live was already set
+   * @throws IllegalStateException if {@link #expireAfterAccess} was already set
    */
   @SuppressWarnings("GoodTime") // should accept a java.time.Duration
   public CacheBuilder<K, V> expireAfterAccess(long duration, TimeUnit unit) {
@@ -722,7 +765,8 @@ long getExpireAfterAccessNanos() {
    * operations.
    *
    * <p>Currently automatic refreshes are performed when the first stale request for an entry
-   * occurs. The request triggering refresh will make a blocking call to {@link CacheLoader#reload}
+   * occurs. The request triggering refresh will make a synchronous call to {@link
+   * CacheLoader#reload}
    * and immediately return the new value if the returned future is complete, and the old value
    * otherwise.
    *
@@ -733,7 +777,7 @@ long getExpireAfterAccessNanos() {
    * @param unit the unit that {@code duration} is expressed in
    * @return this {@code CacheBuilder} instance (for chaining)
    * @throws IllegalArgumentException if {@code duration} is negative
-   * @throws IllegalStateException if the refresh interval was already set
+   * @throws IllegalStateException if {@link #refreshAfterWrite} was already set
    * @since 11.0
    */
   @GwtIncompatible // To be supported (synchronously).
diff --git a/android/guava/src/com/google/common/cache/CacheBuilderSpec.java b/android/guava/src/com/google/common/cache/CacheBuilderSpec.java
index e804866903d8..7757f3bc49a5 100644
--- a/android/guava/src/com/google/common/cache/CacheBuilderSpec.java
+++ b/android/guava/src/com/google/common/cache/CacheBuilderSpec.java
@@ -15,6 +15,7 @@
 package com.google.common.cache;
 
 import static com.google.common.base.Preconditions.checkArgument;
+import static com.google.common.base.Strings.isNullOrEmpty;
 
 import com.google.common.annotations.GwtIncompatible;
 import com.google.common.annotations.VisibleForTesting;
@@ -27,7 +28,8 @@
 import java.util.List;
 import java.util.Locale;
 import java.util.concurrent.TimeUnit;
-import org.checkerframework.checker.nullness.compatqual.NullableDecl;
+import javax.annotation.CheckForNull;
+import org.checkerframework.checker.nullness.qual.Nullable;
 
 /**
  * A specification of a {@link CacheBuilder} configuration.
@@ -78,10 +80,11 @@
  */
 @SuppressWarnings("GoodTime") // lots of violations (nanosecond math)
 @GwtIncompatible
+@ElementTypesAreNonnullByDefault
 public final class CacheBuilderSpec {
   /** Parses a single value. */
   private interface ValueParser {
-    void parse(CacheBuilderSpec spec, String key, @NullableDecl String value);
+    void parse(CacheBuilderSpec spec, String key, @CheckForNull String value);
   }
 
   /** Splits each key-value pair. */
@@ -105,21 +108,21 @@ private interface ValueParser {
           .put("expireAfterWrite", new WriteDurationParser())
           .put("refreshAfterWrite", new RefreshDurationParser())
           .put("refreshInterval", new RefreshDurationParser())
-          .build();
-
-  @VisibleForTesting @NullableDecl Integer initialCapacity;
-  @VisibleForTesting @NullableDecl Long maximumSize;
-  @VisibleForTesting @NullableDecl Long maximumWeight;
-  @VisibleForTesting @NullableDecl Integer concurrencyLevel;
-  @VisibleForTesting @NullableDecl Strength keyStrength;
-  @VisibleForTesting @NullableDecl Strength valueStrength;
-  @VisibleForTesting @NullableDecl Boolean recordStats;
+          .buildOrThrow();
+
+  @VisibleForTesting @CheckForNull Integer initialCapacity;
+  @VisibleForTesting @CheckForNull Long maximumSize;
+  @VisibleForTesting @CheckForNull Long maximumWeight;
+  @VisibleForTesting @CheckForNull Integer concurrencyLevel;
+  @VisibleForTesting @CheckForNull Strength keyStrength;
+  @VisibleForTesting @CheckForNull Strength valueStrength;
+  @VisibleForTesting @CheckForNull Boolean recordStats;
   @VisibleForTesting long writeExpirationDuration;
-  @VisibleForTesting @NullableDecl TimeUnit writeExpirationTimeUnit;
+  @VisibleForTesting @CheckForNull TimeUnit writeExpirationTimeUnit;
   @VisibleForTesting long accessExpirationDuration;
-  @VisibleForTesting @NullableDecl TimeUnit accessExpirationTimeUnit;
+  @VisibleForTesting @CheckForNull TimeUnit accessExpirationTimeUnit;
   @VisibleForTesting long refreshDuration;
-  @VisibleForTesting @NullableDecl TimeUnit refreshTimeUnit;
+  @VisibleForTesting @CheckForNull TimeUnit refreshTimeUnit;
   /** Specification; used for toParseableString(). */
   private final String specification;
 
@@ -248,7 +251,7 @@ public int hashCode() {
   }
 
   @Override
-  public boolean equals(@NullableDecl Object obj) {
+  public boolean equals(@CheckForNull Object obj) {
     if (this == obj) {
       return true;
     }
@@ -278,8 +281,8 @@ public boolean equals(@NullableDecl Object obj) {
    * Converts an expiration duration/unit pair into a single Long for hashing and equality. Uses
    * nanos to match CacheBuilder implementation.
    */
-  @NullableDecl
-  private static Long durationInNanos(long duration, @NullableDecl TimeUnit unit) {
+  @CheckForNull
+  private static Long durationInNanos(long duration, @CheckForNull TimeUnit unit) {
     return (unit == null) ? null : unit.toNanos(duration);
   }
 
@@ -288,8 +291,10 @@ abstract static class IntegerParser implements ValueParser {
     protected abstract void parseInteger(CacheBuilderSpec spec, int value);
 
     @Override
-    public void parse(CacheBuilderSpec spec, String key, String value) {
-      checkArgument(value != null && !value.isEmpty(), "value of key %s omitted", key);
+    public void parse(CacheBuilderSpec spec, String key, @Nullable String value) {
+      if (isNullOrEmpty(value)) {
+        throw new IllegalArgumentException("value of key " + key + " omitted");
+      }
       try {
         parseInteger(spec, Integer.parseInt(value));
       } catch (NumberFormatException e) {
@@ -304,8 +309,10 @@ abstract static class LongParser implements ValueParser {
     protected abstract void parseLong(CacheBuilderSpec spec, long value);
 
     @Override
-    public void parse(CacheBuilderSpec spec, String key, String value) {
-      checkArgument(value != null && !value.isEmpty(), "value of key %s omitted", key);
+    public void parse(CacheBuilderSpec spec, String key, @Nullable String value) {
+      if (isNullOrEmpty(value)) {
+        throw new IllegalArgumentException("value of key " + key + " omitted");
+      }
       try {
         parseLong(spec, Long.parseLong(value));
       } catch (NumberFormatException e) {
@@ -370,7 +377,7 @@ public KeyStrengthParser(Strength strength) {
     }
 
     @Override
-    public void parse(CacheBuilderSpec spec, String key, @NullableDecl String value) {
+    public void parse(CacheBuilderSpec spec, String key, @CheckForNull String value) {
       checkArgument(value == null, "key %s does not take values", key);
       checkArgument(spec.keyStrength == null, "%s was already set to %s", key, spec.keyStrength);
       spec.keyStrength = strength;
@@ -386,7 +393,7 @@ public ValueStrengthParser(Strength strength) {
     }
 
     @Override
-    public void parse(CacheBuilderSpec spec, String key, @NullableDecl String value) {
+    public void parse(CacheBuilderSpec spec, String key, @CheckForNull String value) {
       checkArgument(value == null, "key %s does not take values", key);
       checkArgument(
           spec.valueStrength == null, "%s was already set to %s", key, spec.valueStrength);
@@ -399,7 +406,7 @@ public void parse(CacheBuilderSpec spec, String key, @NullableDecl String value)
   static class RecordStatsParser implements ValueParser {
 
     @Override
-    public void parse(CacheBuilderSpec spec, String key, @NullableDecl String value) {
+    public void parse(CacheBuilderSpec spec, String key, @CheckForNull String value) {
       checkArgument(value == null, "recordStats does not take values");
       checkArgument(spec.recordStats == null, "recordStats already set");
       spec.recordStats = true;
@@ -411,8 +418,10 @@ abstract static class DurationParser implements ValueParser {
     protected abstract void parseDuration(CacheBuilderSpec spec, long duration, TimeUnit unit);
 
     @Override
-    public void parse(CacheBuilderSpec spec, String key, String value) {
-      checkArgument(value != null && !value.isEmpty(), "value of key %s omitted", key);
+    public void parse(CacheBuilderSpec spec, String key, @CheckForNull String value) {
+      if (isNullOrEmpty(value)) {
+        throw new IllegalArgumentException("value of key " + key + " omitted");
+      }
       try {
         char lastChar = value.charAt(value.length() - 1);
         TimeUnit timeUnit;
@@ -431,8 +440,7 @@ public void parse(CacheBuilderSpec spec, String key, String value) {
             break;
           default:
             throw new IllegalArgumentException(
-                format(
-                    "key %s invalid format.  was %s, must end with one of [dDhHmMsS]", key, value));
+                format("key %s invalid unit: was %s, must end with one of [dhms]", key, value));
         }
 
         long duration = Long.parseLong(value.substring(0, value.length() - 1));
diff --git a/android/guava/src/com/google/common/cache/CacheLoader.java b/android/guava/src/com/google/common/cache/CacheLoader.java
index aa1da922b90b..bb544cdcdc01 100644
--- a/android/guava/src/com/google/common/cache/CacheLoader.java
+++ b/android/guava/src/com/google/common/cache/CacheLoader.java
@@ -57,6 +57,7 @@
  * @since 10.0
  */
 @GwtCompatible(emulated = true)
+@ElementTypesAreNonnullByDefault
 public abstract class CacheLoader<K, V> {
   /** Constructor for use by subclasses. */
   protected CacheLoader() {}
diff --git a/android/guava/src/com/google/common/cache/CacheStats.java b/android/guava/src/com/google/common/cache/CacheStats.java
index e0c39c3d7e67..8307e942a818 100644
--- a/android/guava/src/com/google/common/cache/CacheStats.java
+++ b/android/guava/src/com/google/common/cache/CacheStats.java
@@ -22,7 +22,7 @@
 import com.google.common.base.MoreObjects;
 import com.google.common.base.Objects;
 import java.util.concurrent.Callable;
-import org.checkerframework.checker.nullness.compatqual.NullableDecl;
+import javax.annotation.CheckForNull;
 
 /**
  * Statistics about the performance of a {@link Cache}. Instances of this class are immutable.
@@ -57,6 +57,7 @@
  * @since 10.0
  */
 @GwtCompatible
+@ElementTypesAreNonnullByDefault
 public final class CacheStats {
   private final long hitCount;
   private final long missCount;
@@ -276,7 +277,7 @@ public int hashCode() {
   }
 
   @Override
-  public boolean equals(@NullableDecl Object object) {
+  public boolean equals(@CheckForNull Object object) {
     if (object instanceof CacheStats) {
       CacheStats other = (CacheStats) object;
       return hitCount == other.hitCount
diff --git a/android/guava/src/com/google/common/cache/ElementTypesAreNonnullByDefault.java b/android/guava/src/com/google/common/cache/ElementTypesAreNonnullByDefault.java
new file mode 100644
index 000000000000..bcf0fcef1c48
--- /dev/null
+++ b/android/guava/src/com/google/common/cache/ElementTypesAreNonnullByDefault.java
@@ -0,0 +1,41 @@
+/*
+ * Copyright (C) 2021 The Guava Authors
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package com.google.common.cache;
+
+import static java.lang.annotation.ElementType.FIELD;
+import static java.lang.annotation.ElementType.METHOD;
+import static java.lang.annotation.ElementType.PARAMETER;
+import static java.lang.annotation.ElementType.TYPE;
+import static java.lang.annotation.RetentionPolicy.RUNTIME;
+
+import com.google.common.annotations.GwtCompatible;
+import java.lang.annotation.Retention;
+import java.lang.annotation.Target;
+import javax.annotation.Nonnull;
+import javax.annotation.meta.TypeQualifierDefault;
+
+/**
+ * Marks all "top-level" types as non-null in a way that is recognized by Kotlin. Note that this
+ * unfortunately includes type-variable usages, so we also provide {@link ParametricNullness} to
+ * "undo" it as best we can.
+ */
+@GwtCompatible
+@Retention(RUNTIME)
+@Target(TYPE)
+@TypeQualifierDefault({FIELD, METHOD, PARAMETER})
+@Nonnull
+@interface ElementTypesAreNonnullByDefault {}
diff --git a/android/guava/src/com/google/common/cache/ForwardingCache.java b/android/guava/src/com/google/common/cache/ForwardingCache.java
index 217042b099e1..f118977b09a3 100644
--- a/android/guava/src/com/google/common/cache/ForwardingCache.java
+++ b/android/guava/src/com/google/common/cache/ForwardingCache.java
@@ -22,7 +22,7 @@
 import java.util.concurrent.Callable;
 import java.util.concurrent.ConcurrentMap;
 import java.util.concurrent.ExecutionException;
-import org.checkerframework.checker.nullness.compatqual.NullableDecl;
+import javax.annotation.CheckForNull;
 
 /**
  * A cache which forwards all its method calls to another cache. Subclasses should override one or
@@ -33,6 +33,7 @@
  * @since 10.0
  */
 @GwtIncompatible
+@ElementTypesAreNonnullByDefault
 public abstract class ForwardingCache<K, V> extends ForwardingObject implements Cache<K, V> {
 
   /** Constructor for use by subclasses. */
@@ -43,7 +44,7 @@ protected ForwardingCache() {}
 
   /** @since 11.0 */
   @Override
-  @NullableDecl
+  @CheckForNull
   public V getIfPresent(Object key) {
     return delegate().getIfPresent(key);
   }
@@ -56,7 +57,11 @@ public V get(K key, Callable<? extends V> valueLoader) throws ExecutionException
 
   /** @since 11.0 */
   @Override
-  public ImmutableMap<K, V> getAllPresent(Iterable<?> keys) {
+  /*
+   * <? extends Object> is mostly the same as <?> to plain Java. But to nullness checkers, they
+   * differ: <? extends Object> means "non-null types," while <?> means "all types."
+   */
+  public ImmutableMap<K, V> getAllPresent(Iterable<? extends Object> keys) {
     return delegate().getAllPresent(keys);
   }
 
@@ -79,7 +84,8 @@ public void invalidate(Object key) {
 
   /** @since 11.0 */
   @Override
-  public void invalidateAll(Iterable<?> keys) {
+  // For discussion of <? extends Object>, see getAllPresent.
+  public void invalidateAll(Iterable<? extends Object> keys) {
     delegate().invalidateAll(keys);
   }
 
diff --git a/android/guava/src/com/google/common/cache/ForwardingLoadingCache.java b/android/guava/src/com/google/common/cache/ForwardingLoadingCache.java
index ba88ded9bbc1..ecd44ca8d8a9 100644
--- a/android/guava/src/com/google/common/cache/ForwardingLoadingCache.java
+++ b/android/guava/src/com/google/common/cache/ForwardingLoadingCache.java
@@ -31,6 +31,7 @@
  * @since 11.0
  */
 @GwtIncompatible
+@ElementTypesAreNonnullByDefault
 public abstract class ForwardingLoadingCache<K, V> extends ForwardingCache<K, V>
     implements LoadingCache<K, V> {
 
diff --git a/android/guava/src/com/google/common/cache/LoadingCache.java b/android/guava/src/com/google/common/cache/LoadingCache.java
index 9e812c3ac9bf..e338ac4c3733 100644
--- a/android/guava/src/com/google/common/cache/LoadingCache.java
+++ b/android/guava/src/com/google/common/cache/LoadingCache.java
@@ -33,10 +33,13 @@
  * <p>When evaluated as a {@link Function}, a cache yields the same result as invoking {@link
  * #getUnchecked}.
  *
+ * @param <K> the type of the cache's keys, which are not permitted to be null
+ * @param <V> the type of the cache's values, which are not permitted to be null
  * @author Charles Fry
  * @since 11.0
  */
 @GwtCompatible
+@ElementTypesAreNonnullByDefault
 public interface LoadingCache<K, V> extends Cache<K, V>, Function<K, V> {
 
   /**
diff --git a/android/guava/src/com/google/common/cache/LocalCache.java b/android/guava/src/com/google/common/cache/LocalCache.java
index 4ec9320153cb..f3744e59cbff 100644
--- a/android/guava/src/com/google/common/cache/LocalCache.java
+++ b/android/guava/src/com/google/common/cache/LocalCache.java
@@ -21,6 +21,7 @@
 import static com.google.common.util.concurrent.Futures.transform;
 import static com.google.common.util.concurrent.MoreExecutors.directExecutor;
 import static com.google.common.util.concurrent.Uninterruptibles.getUninterruptibly;
+import static java.util.Collections.unmodifiableSet;
 import static java.util.concurrent.TimeUnit.NANOSECONDS;
 
 import com.google.common.annotations.GwtCompatible;
@@ -36,6 +37,7 @@
 import com.google.common.cache.CacheBuilder.OneWeigher;
 import com.google.common.cache.CacheLoader.InvalidCacheLoadException;
 import com.google.common.cache.CacheLoader.UnsupportedLoadingOperationException;
+import com.google.common.cache.LocalCache.AbstractCacheSet;
 import com.google.common.collect.AbstractSequentialIterator;
 import com.google.common.collect.ImmutableMap;
 import com.google.common.collect.ImmutableSet;
@@ -81,7 +83,7 @@
 import java.util.concurrent.locks.ReentrantLock;
 import java.util.logging.Level;
 import java.util.logging.Logger;
-import org.checkerframework.checker.nullness.compatqual.NullableDecl;
+import javax.annotation.CheckForNull;
 
 /**
  * The concurrent hash map implementation built by {@link CacheBuilder}.
@@ -93,8 +95,12 @@
  * @author Bob Lee ({@code com.google.common.collect.MapMaker})
  * @author Doug Lea ({@code ConcurrentHashMap})
  */
-@SuppressWarnings("GoodTime") // lots of violations (nanosecond math)
+@SuppressWarnings({
+  "GoodTime", // lots of violations (nanosecond math)
+  "nullness", // too much trouble for the payoff
+})
 @GwtCompatible(emulated = true)
+// TODO(cpovirk): Annotate for nullness.
 class LocalCache<K, V> extends AbstractMap<K, V> implements ConcurrentMap<K, V> {
 
   /*
@@ -226,13 +232,13 @@ class LocalCache<K, V> extends AbstractMap<K, V> implements ConcurrentMap<K, V>
   final StatsCounter globalStatsCounter;
 
   /** The default cache loader to use on loading operations. */
-  @NullableDecl final CacheLoader<? super K, V> defaultLoader;
+  @CheckForNull final CacheLoader<? super K, V> defaultLoader;
 
   /**
    * Creates a new, empty map with the specified strategy, initial capacity and concurrency level.
    */
   LocalCache(
-      CacheBuilder<? super K, ? super V> builder, @NullableDecl CacheLoader<? super K, V> loader) {
+      CacheBuilder<? super K, ? super V> builder, @CheckForNull CacheLoader<? super K, V> loader) {
     concurrencyLevel = Math.min(builder.getConcurrencyLevel(), MAX_SEGMENTS);
 
     keyStrength = builder.getKeyStrength();
@@ -436,14 +442,14 @@ enum EntryFactory {
     STRONG {
       @Override
       <K, V> ReferenceEntry<K, V> newEntry(
-          Segment<K, V> segment, K key, int hash, @NullableDecl ReferenceEntry<K, V> next) {
+          Segment<K, V> segment, K key, int hash, @CheckForNull ReferenceEntry<K, V> next) {
         return new StrongEntry<>(key, hash, next);
       }
     },
     STRONG_ACCESS {
       @Override
       <K, V> ReferenceEntry<K, V> newEntry(
-          Segment<K, V> segment, K key, int hash, @NullableDecl ReferenceEntry<K, V> next) {
+          Segment<K, V> segment, K key, int hash, @CheckForNull ReferenceEntry<K, V> next) {
         return new StrongAccessEntry<>(key, hash, next);
       }
 
@@ -458,7 +464,7 @@ <K, V> ReferenceEntry<K, V> copyEntry(
     STRONG_WRITE {
       @Override
       <K, V> ReferenceEntry<K, V> newEntry(
-          Segment<K, V> segment, K key, int hash, @NullableDecl ReferenceEntry<K, V> next) {
+          Segment<K, V> segment, K key, int hash, @CheckForNull ReferenceEntry<K, V> next) {
         return new StrongWriteEntry<>(key, hash, next);
       }
 
@@ -473,7 +479,7 @@ <K, V> ReferenceEntry<K, V> copyEntry(
     STRONG_ACCESS_WRITE {
       @Override
       <K, V> ReferenceEntry<K, V> newEntry(
-          Segment<K, V> segment, K key, int hash, @NullableDecl ReferenceEntry<K, V> next) {
+          Segment<K, V> segment, K key, int hash, @CheckForNull ReferenceEntry<K, V> next) {
         return new StrongAccessWriteEntry<>(key, hash, next);
       }
 
@@ -489,14 +495,14 @@ <K, V> ReferenceEntry<K, V> copyEntry(
     WEAK {
       @Override
       <K, V> ReferenceEntry<K, V> newEntry(
-          Segment<K, V> segment, K key, int hash, @NullableDecl ReferenceEntry<K, V> next) {
+          Segment<K, V> segment, K key, int hash, @CheckForNull ReferenceEntry<K, V> next) {
         return new WeakEntry<>(segment.keyReferenceQueue, key, hash, next);
       }
     },
     WEAK_ACCESS {
       @Override
       <K, V> ReferenceEntry<K, V> newEntry(
-          Segment<K, V> segment, K key, int hash, @NullableDecl ReferenceEntry<K, V> next) {
+          Segment<K, V> segment, K key, int hash, @CheckForNull ReferenceEntry<K, V> next) {
         return new WeakAccessEntry<>(segment.keyReferenceQueue, key, hash, next);
       }
 
@@ -511,7 +517,7 @@ <K, V> ReferenceEntry<K, V> copyEntry(
     WEAK_WRITE {
       @Override
       <K, V> ReferenceEntry<K, V> newEntry(
-          Segment<K, V> segment, K key, int hash, @NullableDecl ReferenceEntry<K, V> next) {
+          Segment<K, V> segment, K key, int hash, @CheckForNull ReferenceEntry<K, V> next) {
         return new WeakWriteEntry<>(segment.keyReferenceQueue, key, hash, next);
       }
 
@@ -526,7 +532,7 @@ <K, V> ReferenceEntry<K, V> copyEntry(
     WEAK_ACCESS_WRITE {
       @Override
       <K, V> ReferenceEntry<K, V> newEntry(
-          Segment<K, V> segment, K key, int hash, @NullableDecl ReferenceEntry<K, V> next) {
+          Segment<K, V> segment, K key, int hash, @CheckForNull ReferenceEntry<K, V> next) {
         return new WeakAccessWriteEntry<>(segment.keyReferenceQueue, key, hash, next);
       }
 
@@ -576,7 +582,7 @@ static EntryFactory getFactory(
      * @param next entry in the same bucket
      */
     abstract <K, V> ReferenceEntry<K, V> newEntry(
-        Segment<K, V> segment, K key, int hash, @NullableDecl ReferenceEntry<K, V> next);
+        Segment<K, V> segment, K key, int hash, @CheckForNull ReferenceEntry<K, V> next);
 
     /**
      * Copies an entry, assigning it a new {@code next} entry.
@@ -618,7 +624,7 @@ <K, V> void copyWriteEntry(ReferenceEntry<K, V> original, ReferenceEntry<K, V> n
   /** A reference to a value. */
   interface ValueReference<K, V> {
     /** Returns the value. Does not block or throw exceptions. */
-    @NullableDecl
+    @CheckForNull
     V get();
 
     /**
@@ -637,7 +643,7 @@ interface ValueReference<K, V> {
      * Returns the entry associated with this value reference, or {@code null} if this value
      * reference is independent of any entry.
      */
-    @NullableDecl
+    @CheckForNull
     ReferenceEntry<K, V> getEntry();
 
     /**
@@ -646,13 +652,13 @@ interface ValueReference<K, V> {
      * <p>{@code value} may be null only for a loading reference.
      */
     ValueReference<K, V> copyFor(
-        ReferenceQueue<V> queue, @NullableDecl V value, ReferenceEntry<K, V> entry);
+        ReferenceQueue<V> queue, @CheckForNull V value, ReferenceEntry<K, V> entry);
 
     /**
      * Notify pending loads that a new value was set. This is only relevant to loading value
      * references.
      */
-    void notifyNewValue(@NullableDecl V newValue);
+    void notifyNewValue(@CheckForNull V newValue);
 
     /**
      * Returns true if a new value is currently loading, regardless of whether or not there is an
@@ -692,7 +698,7 @@ public ReferenceEntry<Object, Object> getEntry() {
         @Override
         public ValueReference<Object, Object> copyFor(
             ReferenceQueue<Object> queue,
-            @NullableDecl Object value,
+            @CheckForNull Object value,
             ReferenceEntry<Object, Object> entry) {
           return this;
         }
@@ -935,7 +941,7 @@ static <E> Queue<E> discardingQueue() {
   static class StrongEntry<K, V> extends AbstractReferenceEntry<K, V> {
     final K key;
 
-    StrongEntry(K key, int hash, @NullableDecl ReferenceEntry<K, V> next) {
+    StrongEntry(K key, int hash, @CheckForNull ReferenceEntry<K, V> next) {
       this.key = key;
       this.hash = hash;
       this.next = next;
@@ -949,7 +955,7 @@ public K getKey() {
     // The code below is exactly the same for each entry type.
 
     final int hash;
-    @NullableDecl final ReferenceEntry<K, V> next;
+    @CheckForNull final ReferenceEntry<K, V> next;
     volatile ValueReference<K, V> valueReference = unset();
 
     @Override
@@ -974,7 +980,7 @@ public ReferenceEntry<K, V> getNext() {
   }
 
   static final class StrongAccessEntry<K, V> extends StrongEntry<K, V> {
-    StrongAccessEntry(K key, int hash, @NullableDecl ReferenceEntry<K, V> next) {
+    StrongAccessEntry(K key, int hash, @CheckForNull ReferenceEntry<K, V> next) {
       super(key, hash, next);
     }
 
@@ -1020,7 +1026,7 @@ public void setPreviousInAccessQueue(ReferenceEntry<K, V> previous) {
   }
 
   static final class StrongWriteEntry<K, V> extends StrongEntry<K, V> {
-    StrongWriteEntry(K key, int hash, @NullableDecl ReferenceEntry<K, V> next) {
+    StrongWriteEntry(K key, int hash, @CheckForNull ReferenceEntry<K, V> next) {
       super(key, hash, next);
     }
 
@@ -1066,7 +1072,7 @@ public void setPreviousInWriteQueue(ReferenceEntry<K, V> previous) {
   }
 
   static final class StrongAccessWriteEntry<K, V> extends StrongEntry<K, V> {
-    StrongAccessWriteEntry(K key, int hash, @NullableDecl ReferenceEntry<K, V> next) {
+    StrongAccessWriteEntry(K key, int hash, @CheckForNull ReferenceEntry<K, V> next) {
       super(key, hash, next);
     }
 
@@ -1153,7 +1159,7 @@ public void setPreviousInWriteQueue(ReferenceEntry<K, V> previous) {
 
   /** Used for weakly-referenced keys. */
   static class WeakEntry<K, V> extends WeakReference<K> implements ReferenceEntry<K, V> {
-    WeakEntry(ReferenceQueue<K> queue, K key, int hash, @NullableDecl ReferenceEntry<K, V> next) {
+    WeakEntry(ReferenceQueue<K> queue, K key, int hash, @CheckForNull ReferenceEntry<K, V> next) {
       super(key, queue);
       this.hash = hash;
       this.next = next;
@@ -1236,7 +1242,7 @@ public void setPreviousInWriteQueue(ReferenceEntry<K, V> previous) {
     // The code below is exactly the same for each entry type.
 
     final int hash;
-    @NullableDecl final ReferenceEntry<K, V> next;
+    @CheckForNull final ReferenceEntry<K, V> next;
     volatile ValueReference<K, V> valueReference = unset();
 
     @Override
@@ -1262,7 +1268,7 @@ public ReferenceEntry<K, V> getNext() {
 
   static final class WeakAccessEntry<K, V> extends WeakEntry<K, V> {
     WeakAccessEntry(
-        ReferenceQueue<K> queue, K key, int hash, @NullableDecl ReferenceEntry<K, V> next) {
+        ReferenceQueue<K> queue, K key, int hash, @CheckForNull ReferenceEntry<K, V> next) {
       super(queue, key, hash, next);
     }
 
@@ -1309,7 +1315,7 @@ public void setPreviousInAccessQueue(ReferenceEntry<K, V> previous) {
 
   static final class WeakWriteEntry<K, V> extends WeakEntry<K, V> {
     WeakWriteEntry(
-        ReferenceQueue<K> queue, K key, int hash, @NullableDecl ReferenceEntry<K, V> next) {
+        ReferenceQueue<K> queue, K key, int hash, @CheckForNull ReferenceEntry<K, V> next) {
       super(queue, key, hash, next);
     }
 
@@ -1356,7 +1362,7 @@ public void setPreviousInWriteQueue(ReferenceEntry<K, V> previous) {
 
   static final class WeakAccessWriteEntry<K, V> extends WeakEntry<K, V> {
     WeakAccessWriteEntry(
-        ReferenceQueue<K> queue, K key, int hash, @NullableDecl ReferenceEntry<K, V> next) {
+        ReferenceQueue<K> queue, K key, int hash, @CheckForNull ReferenceEntry<K, V> next) {
       super(queue, key, hash, next);
     }
 
@@ -1660,7 +1666,7 @@ static int rehash(int h) {
    * This method is a convenience for testing. Code should call {@link Segment#newEntry} directly.
    */
   @VisibleForTesting
-  ReferenceEntry<K, V> newEntry(K key, int hash, @NullableDecl ReferenceEntry<K, V> next) {
+  ReferenceEntry<K, V> newEntry(K key, int hash, @CheckForNull ReferenceEntry<K, V> next) {
     Segment<K, V> segment = segmentFor(hash);
     segment.lock();
     try {
@@ -1691,7 +1697,7 @@ ValueReference<K, V> newValueReference(ReferenceEntry<K, V> entry, V value, int
     return valueStrength.referenceValue(segmentFor(hash), entry, checkNotNull(value), weight);
   }
 
-  int hash(@NullableDecl Object key) {
+  int hash(@CheckForNull Object key) {
     int h = keyEquivalence.hash(key);
     return rehash(h);
   }
@@ -1738,7 +1744,7 @@ Segment<K, V> createSegment(
    * cleanup stale entries. As such it should only be called outside of a segment context, such as
    * during iteration.
    */
-  @NullableDecl
+  @CheckForNull
   V getLiveValue(ReferenceEntry<K, V> entry, long now) {
     if (entry.getKey() == null) {
       return null;
@@ -1883,7 +1889,7 @@ static class Segment<K, V> extends ReentrantLock {
     int threshold;
 
     /** The per-segment table. */
-    @NullableDecl volatile AtomicReferenceArray<ReferenceEntry<K, V>> table;
+    @CheckForNull volatile AtomicReferenceArray<ReferenceEntry<K, V>> table;
 
     /** The maximum weight of this segment. UNSET_INT if there is no maximum. */
     final long maxSegmentWeight;
@@ -1892,13 +1898,13 @@ static class Segment<K, V> extends ReentrantLock {
      * The key reference queue contains entries whose keys have been garbage collected, and which
      * need to be cleaned up internally.
      */
-    @NullableDecl final ReferenceQueue<K> keyReferenceQueue;
+    @CheckForNull final ReferenceQueue<K> keyReferenceQueue;
 
     /**
      * The value reference queue contains value references whose values have been garbage collected,
      * and which need to be cleaned up internally.
      */
-    @NullableDecl final ReferenceQueue<V> valueReferenceQueue;
+    @CheckForNull final ReferenceQueue<V> valueReferenceQueue;
 
     /**
      * The recency queue is used to record which entries were accessed for updating the access
@@ -1974,7 +1980,7 @@ void initTable(AtomicReferenceArray<ReferenceEntry<K, V>> newTable) {
     }
 
     @GuardedBy("this")
-    ReferenceEntry<K, V> newEntry(K key, int hash, @NullableDecl ReferenceEntry<K, V> next) {
+    ReferenceEntry<K, V> newEntry(K key, int hash, @CheckForNull ReferenceEntry<K, V> next) {
       return map.entryFactory.newEntry(this, checkNotNull(key), hash, next);
     }
 
@@ -2054,7 +2060,7 @@ V get(K key, int hash, CacheLoader<? super K, V> loader) throws ExecutionExcepti
       }
     }
 
-    @NullableDecl
+    @CheckForNull
     V get(Object key, int hash) {
       try {
         if (count != 0) { // read-volatile
@@ -2265,7 +2271,7 @@ V scheduleRefresh(
      * {@code null} if another thread is performing the refresh or if an error occurs during
      * refresh.
      */
-    @NullableDecl
+    @CheckForNull
     V refresh(K key, int hash, CacheLoader<? super K, V> loader, boolean checkTime) {
       final LoadingValueReference<K, V> loadingValueReference =
           insertLoadingValueReference(key, hash, checkTime);
@@ -2288,7 +2294,7 @@ V refresh(K key, int hash, CacheLoader<? super K, V> loader, boolean checkTime)
      * Returns a newly inserted {@code LoadingValueReference}, or null if the live value reference
      * is already loading.
      */
-    @NullableDecl
+    @CheckForNull
     LoadingValueReference<K, V> insertLoadingValueReference(
         final K key, final int hash, boolean checkTime) {
       ReferenceEntry<K, V> e = null;
@@ -2518,7 +2524,7 @@ void expireEntries(long now) {
 
     @GuardedBy("this")
     void enqueueNotification(
-        @NullableDecl K key, int hash, @NullableDecl V value, int weight, RemovalCause cause) {
+        @CheckForNull K key, int hash, @CheckForNull V value, int weight, RemovalCause cause) {
       totalWeight -= weight;
       if (cause.wasEvicted()) {
         statsCounter.recordEviction();
@@ -2580,7 +2586,7 @@ ReferenceEntry<K, V> getFirst(int hash) {
 
     // Specialized implementations of map methods
 
-    @NullableDecl
+    @CheckForNull
     ReferenceEntry<K, V> getEntry(Object key, int hash) {
       for (ReferenceEntry<K, V> e = getFirst(hash); e != null; e = e.getNext()) {
         if (e.getHash() != hash) {
@@ -2601,7 +2607,7 @@ ReferenceEntry<K, V> getEntry(Object key, int hash) {
       return null;
     }
 
-    @NullableDecl
+    @CheckForNull
     ReferenceEntry<K, V> getLiveEntry(Object key, int hash, long now) {
       ReferenceEntry<K, V> e = getEntry(key, hash);
       if (e == null) {
@@ -2682,7 +2688,7 @@ boolean containsValue(Object value) {
       }
     }
 
-    @NullableDecl
+    @CheckForNull
     V put(K key, int hash, V value, boolean onlyIfAbsent) {
       lock();
       try {
@@ -2888,7 +2894,7 @@ boolean replace(K key, int hash, V oldValue, V newValue) {
       }
     }
 
-    @NullableDecl
+    @CheckForNull
     V replace(K key, int hash, V newValue) {
       lock();
       try {
@@ -2943,7 +2949,7 @@ V replace(K key, int hash, V newValue) {
       }
     }
 
-    @NullableDecl
+    @CheckForNull
     V remove(Object key, int hash) {
       lock();
       try {
@@ -3135,11 +3141,11 @@ void clear() {
     }
 
     @GuardedBy("this")
-    @NullableDecl
+    @CheckForNull
     ReferenceEntry<K, V> removeValueFromChain(
         ReferenceEntry<K, V> first,
         ReferenceEntry<K, V> entry,
-        @NullableDecl K key,
+        @CheckForNull K key,
         int hash,
         V value,
         ValueReference<K, V> valueReference,
@@ -3157,7 +3163,7 @@ ReferenceEntry<K, V> removeValueFromChain(
     }
 
     @GuardedBy("this")
-    @NullableDecl
+    @CheckForNull
     ReferenceEntry<K, V> removeEntryFromChain(
         ReferenceEntry<K, V> first, ReferenceEntry<K, V> entry) {
       int newCount = count;
@@ -3411,7 +3417,7 @@ public int getWeight() {
       return oldValue.getWeight();
     }
 
-    public boolean set(@NullableDecl V newValue) {
+    public boolean set(@CheckForNull V newValue) {
       return futureValue.set(newValue);
     }
 
@@ -3424,7 +3430,7 @@ private ListenableFuture<V> fullyFailedFuture(Throwable t) {
     }
 
     @Override
-    public void notifyNewValue(@NullableDecl V newValue) {
+    public void notifyNewValue(@CheckForNull V newValue) {
       if (newValue != null) {
         // The pending load was clobbered by a manual write.
         // Unblock all pending gets, and have them return the new value.
@@ -3495,7 +3501,7 @@ public ReferenceEntry<K, V> getEntry() {
 
     @Override
     public ValueReference<K, V> copyFor(
-        ReferenceQueue<V> queue, @NullableDecl V value, ReferenceEntry<K, V> entry) {
+        ReferenceQueue<V> queue, @CheckForNull V value, ReferenceEntry<K, V> entry) {
       return this;
     }
   }
@@ -3835,8 +3841,8 @@ public int size() {
   }
 
   @Override
-  @NullableDecl
-  public V get(@NullableDecl Object key) {
+  @CheckForNull
+  public V get(@CheckForNull Object key) {
     if (key == null) {
       return null;
     }
@@ -3849,7 +3855,7 @@ V get(K key, CacheLoader<? super K, V> loader) throws ExecutionException {
     return segmentFor(hash).get(key, hash, loader);
   }
 
-  @NullableDecl
+  @CheckForNull
   public V getIfPresent(Object key) {
     int hash = hash(checkNotNull(key));
     V value = segmentFor(hash).get(key, hash);
@@ -3862,8 +3868,8 @@ public V getIfPresent(Object key) {
   }
 
   @SuppressWarnings("MissingOverride") // Supermethod will not exist if we build with --release 7.
-  @NullableDecl
-  public V getOrDefault(@NullableDecl Object key, @NullableDecl V defaultValue) {
+  @CheckForNull
+  public V getOrDefault(@CheckForNull Object key, @CheckForNull V defaultValue) {
     V result = get(key);
     return (result != null) ? result : defaultValue;
   }
@@ -3876,7 +3882,7 @@ ImmutableMap<K, V> getAllPresent(Iterable<?> keys) {
     int hits = 0;
     int misses = 0;
 
-    Map<K, V> result = Maps.newLinkedHashMap();
+    ImmutableMap.Builder<K, V> result = ImmutableMap.builder();
     for (Object key : keys) {
       V value = get(key);
       if (value == null) {
@@ -3891,7 +3897,7 @@ ImmutableMap<K, V> getAllPresent(Iterable<?> keys) {
     }
     globalStatsCounter.recordHits(hits);
     globalStatsCounter.recordMisses(misses);
-    return ImmutableMap.copyOf(result);
+    return result.buildKeepingLast();
   }
 
   ImmutableMap<K, V> getAll(Iterable<? extends K> keys) throws ExecutionException {
@@ -3916,7 +3922,7 @@ ImmutableMap<K, V> getAll(Iterable<? extends K> keys) throws ExecutionException
     try {
       if (!keysToLoad.isEmpty()) {
         try {
-          Map<K, V> newEntries = loadAll(keysToLoad, defaultLoader);
+          Map<K, V> newEntries = loadAll(unmodifiableSet(keysToLoad), defaultLoader);
           for (K key : keysToLoad) {
             V value = newEntries.get(key);
             if (value == null) {
@@ -3943,7 +3949,7 @@ ImmutableMap<K, V> getAll(Iterable<? extends K> keys) throws ExecutionException
    * Returns the result of calling {@link CacheLoader#loadAll}, or null if {@code loader} doesn't
    * implement {@code loadAll}.
    */
-  @NullableDecl
+  @CheckForNull
   Map<K, V> loadAll(Set<? extends K> keys, CacheLoader<? super K, V> loader)
       throws ExecutionException {
     checkNotNull(loader);
@@ -4007,7 +4013,7 @@ Map<K, V> loadAll(Set<? extends K> keys, CacheLoader<? super K, V> loader)
    * Returns the internal entry for the specified key. The entry may be loading, expired, or
    * partially collected.
    */
-  ReferenceEntry<K, V> getEntry(@NullableDecl Object key) {
+  ReferenceEntry<K, V> getEntry(@CheckForNull Object key) {
     // does not impact recency ordering
     if (key == null) {
       return null;
@@ -4022,7 +4028,7 @@ void refresh(K key) {
   }
 
   @Override
-  public boolean containsKey(@NullableDecl Object key) {
+  public boolean containsKey(@CheckForNull Object key) {
     // does not impact recency ordering
     if (key == null) {
       return false;
@@ -4032,7 +4038,7 @@ public boolean containsKey(@NullableDecl Object key) {
   }
 
   @Override
-  public boolean containsValue(@NullableDecl Object value) {
+  public boolean containsValue(@CheckForNull Object value) {
     // does not impact recency ordering
     if (value == null) {
       return false;
@@ -4095,7 +4101,7 @@ public void putAll(Map<? extends K, ? extends V> m) {
   }
 
   @Override
-  public V remove(@NullableDecl Object key) {
+  public V remove(@CheckForNull Object key) {
     if (key == null) {
       return null;
     }
@@ -4104,7 +4110,7 @@ public V remove(@NullableDecl Object key) {
   }
 
   @Override
-  public boolean remove(@NullableDecl Object key, @NullableDecl Object value) {
+  public boolean remove(@CheckForNull Object key, @CheckForNull Object value) {
     if (key == null || value == null) {
       return false;
     }
@@ -4113,7 +4119,7 @@ public boolean remove(@NullableDecl Object key, @NullableDecl Object value) {
   }
 
   @Override
-  public boolean replace(K key, @NullableDecl V oldValue, V newValue) {
+  public boolean replace(K key, @CheckForNull V oldValue, V newValue) {
     checkNotNull(key);
     checkNotNull(newValue);
     if (oldValue == null) {
@@ -4145,7 +4151,7 @@ void invalidateAll(Iterable<?> keys) {
     }
   }
 
-  @RetainedWith @NullableDecl Set<K> keySet;
+  @RetainedWith @CheckForNull Set<K> keySet;
 
   @Override
   public Set<K> keySet() {
@@ -4154,7 +4160,7 @@ public Set<K> keySet() {
     return (ks != null) ? ks : (keySet = new KeySet());
   }
 
-  @RetainedWith @NullableDecl Collection<V> values;
+  @RetainedWith @CheckForNull Collection<V> values;
 
   @Override
   public Collection<V> values() {
@@ -4163,7 +4169,7 @@ public Collection<V> values() {
     return (vs != null) ? vs : (values = new Values());
   }
 
-  @RetainedWith @NullableDecl Set<Entry<K, V>> entrySet;
+  @RetainedWith @CheckForNull Set<Entry<K, V>> entrySet;
 
   @Override
   @GwtIncompatible // Not supported.
@@ -4179,11 +4185,11 @@ abstract class HashIterator<T> implements Iterator<T> {
 
     int nextSegmentIndex;
     int nextTableIndex;
-    @NullableDecl Segment<K, V> currentSegment;
-    @NullableDecl AtomicReferenceArray<ReferenceEntry<K, V>> currentTable;
-    @NullableDecl ReferenceEntry<K, V> nextEntry;
-    @NullableDecl WriteThroughEntry nextExternal;
-    @NullableDecl WriteThroughEntry lastReturned;
+    @CheckForNull Segment<K, V> currentSegment;
+    @CheckForNull AtomicReferenceArray<ReferenceEntry<K, V>> currentTable;
+    @CheckForNull ReferenceEntry<K, V> nextEntry;
+    @CheckForNull WriteThroughEntry nextExternal;
+    @CheckForNull WriteThroughEntry lastReturned;
 
     HashIterator() {
       nextSegmentIndex = segments.length - 1;
@@ -4324,7 +4330,7 @@ public V getValue() {
     }
 
     @Override
-    public boolean equals(@NullableDecl Object object) {
+    public boolean equals(@CheckForNull Object object) {
       // Cannot use key and value equivalence
       if (object instanceof Entry) {
         Entry<?, ?> that = (Entry<?, ?>) object;
@@ -4512,10 +4518,10 @@ static class ManualSerializationProxy<K, V> extends ForwardingCache<K, V>
     final Weigher<K, V> weigher;
     final int concurrencyLevel;
     final RemovalListener<? super K, ? super V> removalListener;
-    @NullableDecl final Ticker ticker;
+    @CheckForNull final Ticker ticker;
     final CacheLoader<? super K, V> loader;
 
-    @NullableDecl transient Cache<K, V> delegate;
+    @CheckForNull transient Cache<K, V> delegate;
 
     ManualSerializationProxy(LocalCache<K, V> cache) {
       this(
@@ -4620,7 +4626,7 @@ static final class LoadingSerializationProxy<K, V> extends ManualSerializationPr
       implements LoadingCache<K, V>, Serializable {
     private static final long serialVersionUID = 1;
 
-    @NullableDecl transient LoadingCache<K, V> autoDelegate;
+    @CheckForNull transient LoadingCache<K, V> autoDelegate;
 
     LoadingSerializationProxy(LocalCache<K, V> cache) {
       super(cache);
@@ -4676,7 +4682,7 @@ private LocalManualCache(LocalCache<K, V> localCache) {
     // Cache methods
 
     @Override
-    @NullableDecl
+    @CheckForNull
     public V getIfPresent(Object key) {
       return localCache.getIfPresent(key);
     }
diff --git a/android/guava/src/com/google/common/cache/LongAddable.java b/android/guava/src/com/google/common/cache/LongAddable.java
index eaa641467738..9851052d6817 100644
--- a/android/guava/src/com/google/common/cache/LongAddable.java
+++ b/android/guava/src/com/google/common/cache/LongAddable.java
@@ -22,6 +22,7 @@
  * @author Louis Wasserman
  */
 @GwtCompatible
+@ElementTypesAreNonnullByDefault
 interface LongAddable {
   void increment();
 
diff --git a/android/guava/src/com/google/common/cache/LongAddables.java b/android/guava/src/com/google/common/cache/LongAddables.java
index 203d2ef731a8..249c6e149d95 100644
--- a/android/guava/src/com/google/common/cache/LongAddables.java
+++ b/android/guava/src/com/google/common/cache/LongAddables.java
@@ -24,13 +24,15 @@
  * @author Louis Wasserman
  */
 @GwtCompatible(emulated = true)
+@ElementTypesAreNonnullByDefault
 final class LongAddables {
   private static final Supplier<LongAddable> SUPPLIER;
 
   static {
     Supplier<LongAddable> supplier;
     try {
-      new LongAdder(); // trigger static initialization of the LongAdder class, which may fail
+      // trigger static initialization of the LongAdder class, which may fail
+      LongAdder unused = new LongAdder();
       supplier =
           new Supplier<LongAddable>() {
             @Override
diff --git a/android/guava/src/com/google/common/cache/LongAdder.java b/android/guava/src/com/google/common/cache/LongAdder.java
index f0c44ffbc697..7ead7e8eccd3 100644
--- a/android/guava/src/com/google/common/cache/LongAdder.java
+++ b/android/guava/src/com/google/common/cache/LongAdder.java
@@ -40,6 +40,7 @@
  * @author Doug Lea
  */
 @GwtCompatible(emulated = true)
+@ElementTypesAreNonnullByDefault
 final class LongAdder extends Striped64 implements Serializable, LongAddable {
   private static final long serialVersionUID = 7249069246863182397L;
 
diff --git a/android/guava/src/com/google/common/cache/ParametricNullness.java b/android/guava/src/com/google/common/cache/ParametricNullness.java
new file mode 100644
index 000000000000..64682de55333
--- /dev/null
+++ b/android/guava/src/com/google/common/cache/ParametricNullness.java
@@ -0,0 +1,52 @@
+/*
+ * Copyright (C) 2021 The Guava Authors
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package com.google.common.cache;
+
+import static java.lang.annotation.ElementType.FIELD;
+import static java.lang.annotation.ElementType.METHOD;
+import static java.lang.annotation.ElementType.PARAMETER;
+import static java.lang.annotation.RetentionPolicy.RUNTIME;
+
+import com.google.common.annotations.GwtCompatible;
+import java.lang.annotation.Retention;
+import java.lang.annotation.Target;
+
+/**
+ * Marks a "top-level" type-variable usage as the closest we can get to "non-nullable when
+ * non-nullable; nullable when nullable" (like the Android <a
+ * href="https://android.googlesource.com/platform/libcore/+/master/luni/src/main/java/libcore/util/NullFromTypeParam.java">{@code
+ * NullFromTypeParam}</a>).
+ *
+ * <p>Consumers of this annotation include:
+ *
+ * <ul>
+ *   <li>Kotlin, for which it makes the type-variable usage (a) a Kotlin platform type when the type
+ *       argument is non-nullable and (b) nullable when the type argument is nullable. We use this
+ *       to "undo" {@link ElementTypesAreNonnullByDefault}.
+ *   <li><a href="https://developers.google.com/j2objc">J2ObjC</a>
+ *   <li>{@code NullPointerTester}, at least in the Android backport (where the type-use annotations
+ *       {@code NullPointerTester} would need are not available) and in case of <a
+ *       href="https://bugs.openjdk.java.net/browse/JDK-8202469">JDK-8202469</a>
+ * </ul>
+ *
+ */
+@GwtCompatible
+@Retention(RUNTIME)
+@Target({FIELD, METHOD, PARAMETER})
+@javax.annotation.meta.TypeQualifierNickname
+@javax.annotation.Nonnull(when = javax.annotation.meta.When.UNKNOWN)
+@interface ParametricNullness {}
diff --git a/android/guava/src/com/google/common/cache/ReferenceEntry.java b/android/guava/src/com/google/common/cache/ReferenceEntry.java
index f9027ab641d9..8ff2e6c9b4ff 100644
--- a/android/guava/src/com/google/common/cache/ReferenceEntry.java
+++ b/android/guava/src/com/google/common/cache/ReferenceEntry.java
@@ -16,7 +16,7 @@
 
 import com.google.common.annotations.GwtIncompatible;
 import com.google.common.cache.LocalCache.ValueReference;
-import org.checkerframework.checker.nullness.compatqual.NullableDecl;
+import javax.annotation.CheckForNull;
 
 /**
  * An entry in a reference map.
@@ -39,22 +39,24 @@
  * </ul>
  */
 @GwtIncompatible
+@ElementTypesAreNonnullByDefault
 interface ReferenceEntry<K, V> {
   /** Returns the value reference from this entry. */
+  @CheckForNull
   ValueReference<K, V> getValueReference();
 
   /** Sets the value reference for this entry. */
   void setValueReference(ValueReference<K, V> valueReference);
 
   /** Returns the next entry in the chain. */
-  @NullableDecl
+  @CheckForNull
   ReferenceEntry<K, V> getNext();
 
   /** Returns the entry's hash. */
   int getHash();
 
   /** Returns the key for this entry. */
-  @NullableDecl
+  @CheckForNull
   K getKey();
 
   /*
diff --git a/android/guava/src/com/google/common/cache/RemovalCause.java b/android/guava/src/com/google/common/cache/RemovalCause.java
index 8ecc1d662736..2e68e68b582c 100644
--- a/android/guava/src/com/google/common/cache/RemovalCause.java
+++ b/android/guava/src/com/google/common/cache/RemovalCause.java
@@ -26,6 +26,7 @@
  * @since 10.0
  */
 @GwtCompatible
+@ElementTypesAreNonnullByDefault
 public enum RemovalCause {
   /**
    * The entry was manually removed by the user. This can result from the user invoking {@link
diff --git a/android/guava/src/com/google/common/cache/RemovalListener.java b/android/guava/src/com/google/common/cache/RemovalListener.java
index 5e738bfa3c19..a7472d74c6c7 100644
--- a/android/guava/src/com/google/common/cache/RemovalListener.java
+++ b/android/guava/src/com/google/common/cache/RemovalListener.java
@@ -33,6 +33,7 @@
  * @since 10.0
  */
 @GwtCompatible
+@ElementTypesAreNonnullByDefault
 public interface RemovalListener<K, V> {
   /**
    * Notifies the listener that a removal occurred at some point in the past.
diff --git a/android/guava/src/com/google/common/cache/RemovalListeners.java b/android/guava/src/com/google/common/cache/RemovalListeners.java
index c82b0941207f..38edf35287af 100644
--- a/android/guava/src/com/google/common/cache/RemovalListeners.java
+++ b/android/guava/src/com/google/common/cache/RemovalListeners.java
@@ -26,6 +26,7 @@
  * @since 10.0
  */
 @GwtIncompatible
+@ElementTypesAreNonnullByDefault
 public final class RemovalListeners {
 
   private RemovalListeners() {}
@@ -38,20 +39,10 @@ private RemovalListeners() {}
    * @param executor the executor with which removal notifications are asynchronously executed
    */
   public static <K, V> RemovalListener<K, V> asynchronous(
-      final RemovalListener<K, V> listener, final Executor executor) {
+      RemovalListener<K, V> listener, Executor executor) {
     checkNotNull(listener);
     checkNotNull(executor);
-    return new RemovalListener<K, V>() {
-      @Override
-      public void onRemoval(final RemovalNotification<K, V> notification) {
-        executor.execute(
-            new Runnable() {
-              @Override
-              public void run() {
-                listener.onRemoval(notification);
-              }
-            });
-      }
-    };
+    return (RemovalNotification<K, V> notification) ->
+        executor.execute(() -> listener.onRemoval(notification));
   }
 }
diff --git a/android/guava/src/com/google/common/cache/RemovalNotification.java b/android/guava/src/com/google/common/cache/RemovalNotification.java
index e30ec0c05dec..b96fc570911f 100644
--- a/android/guava/src/com/google/common/cache/RemovalNotification.java
+++ b/android/guava/src/com/google/common/cache/RemovalNotification.java
@@ -18,7 +18,8 @@
 
 import com.google.common.annotations.GwtCompatible;
 import java.util.AbstractMap.SimpleImmutableEntry;
-import org.checkerframework.checker.nullness.compatqual.NullableDecl;
+import javax.annotation.CheckForNull;
+import org.checkerframework.checker.nullness.qual.Nullable;
 
 /**
  * A notification of the removal of a single entry. The key and/or value may be null if they were
@@ -32,7 +33,9 @@
  * @since 10.0
  */
 @GwtCompatible
-public final class RemovalNotification<K, V> extends SimpleImmutableEntry<K, V> {
+@ElementTypesAreNonnullByDefault
+public final class RemovalNotification<K, V>
+    extends SimpleImmutableEntry<@Nullable K, @Nullable V> {
   private final RemovalCause cause;
 
   /**
@@ -43,11 +46,11 @@ public final class RemovalNotification<K, V> extends SimpleImmutableEntry<K, V>
    * @since 19.0
    */
   public static <K, V> RemovalNotification<K, V> create(
-      @NullableDecl K key, @NullableDecl V value, RemovalCause cause) {
-    return new RemovalNotification(key, value, cause);
+      @CheckForNull K key, @CheckForNull V value, RemovalCause cause) {
+    return new RemovalNotification<>(key, value, cause);
   }
 
-  private RemovalNotification(@NullableDecl K key, @NullableDecl V value, RemovalCause cause) {
+  private RemovalNotification(@CheckForNull K key, @CheckForNull V value, RemovalCause cause) {
     super(key, value);
     this.cause = checkNotNull(cause);
   }
diff --git a/android/guava/src/com/google/common/cache/Striped64.java b/android/guava/src/com/google/common/cache/Striped64.java
index 676e09aa6bc5..0d2d75b9f384 100644
--- a/android/guava/src/com/google/common/cache/Striped64.java
+++ b/android/guava/src/com/google/common/cache/Striped64.java
@@ -13,7 +13,8 @@
 
 import com.google.common.annotations.GwtIncompatible;
 import java.util.Random;
-import org.checkerframework.checker.nullness.compatqual.NullableDecl;
+import javax.annotation.CheckForNull;
+import org.checkerframework.checker.nullness.qual.Nullable;
 
 /**
  * A package-local class holding common representation and mechanics for classes supporting dynamic
@@ -21,6 +22,7 @@
  * so.
  */
 @GwtIncompatible
+@ElementTypesAreNonnullByDefault
 abstract class Striped64 extends Number {
   /*
    * This class maintains a lazily-initialized table of atomically
@@ -125,7 +127,7 @@ final boolean cas(long cmp, long val) {
    * class, we use a suboptimal int[] representation to avoid introducing a new type that can impede
    * class-unloading when ThreadLocals are not removed.
    */
-  static final ThreadLocal<int[]> threadHashCode = new ThreadLocal<>();
+  static final ThreadLocal<int @Nullable []> threadHashCode = new ThreadLocal<>();
 
   /** Generator of new random hash codes */
   static final Random rng = new Random();
@@ -134,7 +136,7 @@ final boolean cas(long cmp, long val) {
   static final int NCPU = Runtime.getRuntime().availableProcessors();
 
   /** Table of cells. When non-null, size is a power of 2. */
-  @NullableDecl transient volatile Cell[] cells;
+  @CheckForNull transient volatile Cell[] cells;
 
   /**
    * Base value, used mainly when there is no contention, but also as a fallback during table
@@ -177,7 +179,7 @@ final boolean casBusy() {
    * @param hc the hash code holder
    * @param wasUncontended false if CAS failed before call
    */
-  final void retryUpdate(long x, int[] hc, boolean wasUncontended) {
+  final void retryUpdate(long x, @CheckForNull int[] hc, boolean wasUncontended) {
     int h;
     if (hc == null) {
       threadHashCode.set(hc = new int[1]); // Initialize randomly
diff --git a/android/guava/src/com/google/common/cache/Weigher.java b/android/guava/src/com/google/common/cache/Weigher.java
index cf552d44ec11..d5bcd5b21472 100644
--- a/android/guava/src/com/google/common/cache/Weigher.java
+++ b/android/guava/src/com/google/common/cache/Weigher.java
@@ -23,6 +23,7 @@
  * @since 11.0
  */
 @GwtCompatible
+@ElementTypesAreNonnullByDefault
 public interface Weigher<K, V> {
 
   /**
diff --git a/android/guava/src/com/google/common/collect/AbstractBiMap.java b/android/guava/src/com/google/common/collect/AbstractBiMap.java
index 0b314ae4bf3f..151764be8491 100644
--- a/android/guava/src/com/google/common/collect/AbstractBiMap.java
+++ b/android/guava/src/com/google/common/collect/AbstractBiMap.java
@@ -18,7 +18,7 @@
 
 import static com.google.common.base.Preconditions.checkArgument;
 import static com.google.common.base.Preconditions.checkState;
-import static com.google.common.collect.CollectPreconditions.checkRemove;
+import static com.google.common.collect.NullnessCasts.uncheckedCastNullableTToT;
 
 import com.google.common.annotations.GwtCompatible;
 import com.google.common.annotations.GwtIncompatible;
@@ -34,7 +34,8 @@
 import java.util.Iterator;
 import java.util.Map;
 import java.util.Set;
-import org.checkerframework.checker.nullness.compatqual.NullableDecl;
+import javax.annotation.CheckForNull;
+import org.checkerframework.checker.nullness.qual.Nullable;
 
 /**
  * A general-purpose bimap implementation using any two backing {@code Map} instances.
@@ -46,11 +47,12 @@
  * @author Mike Bostock
  */
 @GwtCompatible(emulated = true)
-abstract class AbstractBiMap<K, V> extends ForwardingMap<K, V>
-    implements BiMap<K, V>, Serializable {
+@ElementTypesAreNonnullByDefault
+abstract class AbstractBiMap<K extends @Nullable Object, V extends @Nullable Object>
+    extends ForwardingMap<K, V> implements BiMap<K, V>, Serializable {
 
-  @NullableDecl private transient Map<K, V> delegate;
-  @RetainedWith @NullableDecl transient AbstractBiMap<V, K> inverse;
+  private transient Map<K, V> delegate;
+  @RetainedWith transient AbstractBiMap<V, K> inverse;
 
   /** Package-private constructor for creating a map-backed bimap. */
   AbstractBiMap(Map<K, V> forward, Map<V, K> backward) {
@@ -70,13 +72,15 @@ protected Map<K, V> delegate() {
 
   /** Returns its input, or throws an exception if this is not a valid key. */
   @CanIgnoreReturnValue
-  K checkKey(@NullableDecl K key) {
+  @ParametricNullness
+  K checkKey(@ParametricNullness K key) {
     return key;
   }
 
   /** Returns its input, or throws an exception if this is not a valid value. */
   @CanIgnoreReturnValue
-  V checkValue(@NullableDecl V value) {
+  @ParametricNullness
+  V checkValue(@ParametricNullness V value) {
     return value;
   }
 
@@ -105,7 +109,7 @@ void setInverse(AbstractBiMap<V, K> inverse) {
   // Query Operations (optimizations)
 
   @Override
-  public boolean containsValue(@NullableDecl Object value) {
+  public boolean containsValue(@CheckForNull Object value) {
     return inverse.containsKey(value);
   }
 
@@ -113,17 +117,20 @@ public boolean containsValue(@NullableDecl Object value) {
 
   @CanIgnoreReturnValue
   @Override
-  public V put(@NullableDecl K key, @NullableDecl V value) {
+  @CheckForNull
+  public V put(@ParametricNullness K key, @ParametricNullness V value) {
     return putInBothMaps(key, value, false);
   }
 
   @CanIgnoreReturnValue
   @Override
-  public V forcePut(@NullableDecl K key, @NullableDecl V value) {
+  @CheckForNull
+  public V forcePut(@ParametricNullness K key, @ParametricNullness V value) {
     return putInBothMaps(key, value, true);
   }
 
-  private V putInBothMaps(@NullableDecl K key, @NullableDecl V value, boolean force) {
+  @CheckForNull
+  private V putInBothMaps(@ParametricNullness K key, @ParametricNullness V value, boolean force) {
     checkKey(key);
     checkValue(value);
     boolean containedKey = containsKey(key);
@@ -140,27 +147,35 @@ private V putInBothMaps(@NullableDecl K key, @NullableDecl V value, boolean forc
     return oldValue;
   }
 
-  private void updateInverseMap(K key, boolean containedKey, V oldValue, V newValue) {
+  private void updateInverseMap(
+      @ParametricNullness K key,
+      boolean containedKey,
+      @CheckForNull V oldValue,
+      @ParametricNullness V newValue) {
     if (containedKey) {
-      removeFromInverseMap(oldValue);
+      // The cast is safe because of the containedKey check.
+      removeFromInverseMap(uncheckedCastNullableTToT(oldValue));
     }
     inverse.delegate.put(newValue, key);
   }
 
   @CanIgnoreReturnValue
   @Override
-  public V remove(@NullableDecl Object key) {
+  @CheckForNull
+  public V remove(@CheckForNull Object key) {
     return containsKey(key) ? removeFromBothMaps(key) : null;
   }
 
   @CanIgnoreReturnValue
-  private V removeFromBothMaps(Object key) {
-    V oldValue = delegate.remove(key);
+  @ParametricNullness
+  private V removeFromBothMaps(@CheckForNull Object key) {
+    // The cast is safe because the callers of this method first check that the key is present.
+    V oldValue = uncheckedCastNullableTToT(delegate.remove(key));
     removeFromInverseMap(oldValue);
     return oldValue;
   }
 
-  private void removeFromInverseMap(V oldValue) {
+  private void removeFromInverseMap(@ParametricNullness V oldValue) {
     inverse.delegate.remove(oldValue);
   }
 
@@ -186,7 +201,7 @@ public BiMap<V, K> inverse() {
     return inverse;
   }
 
-  @NullableDecl private transient Set<K> keySet;
+  @CheckForNull private transient Set<K> keySet;
 
   @Override
   public Set<K> keySet() {
@@ -207,7 +222,7 @@ public void clear() {
     }
 
     @Override
-    public boolean remove(Object key) {
+    public boolean remove(@CheckForNull Object key) {
       if (!contains(key)) {
         return false;
       }
@@ -231,7 +246,7 @@ public Iterator<K> iterator() {
     }
   }
 
-  @NullableDecl private transient Set<V> valueSet;
+  @CheckForNull private transient Set<V> valueSet;
 
   @Override
   public Set<V> values() {
@@ -258,12 +273,13 @@ public Iterator<V> iterator() {
     }
 
     @Override
-    public Object[] toArray() {
+    public @Nullable Object[] toArray() {
       return standardToArray();
     }
 
     @Override
-    public <T> T[] toArray(T[] array) {
+    @SuppressWarnings("nullness") // bug in our checker's handling of toArray signatures
+    public <T extends @Nullable Object> T[] toArray(T[] array) {
       return standardToArray(array);
     }
 
@@ -273,7 +289,7 @@ public String toString() {
     }
   }
 
-  @NullableDecl private transient Set<Entry<K, V>> entrySet;
+  @CheckForNull private transient Set<Entry<K, V>> entrySet;
 
   @Override
   public Set<Entry<K, V>> entrySet() {
@@ -313,7 +329,7 @@ public V setValue(V value) {
   Iterator<Entry<K, V>> entrySetIterator() {
     final Iterator<Entry<K, V>> iterator = delegate.entrySet().iterator();
     return new Iterator<Entry<K, V>>() {
-      @NullableDecl Entry<K, V> entry;
+      @CheckForNull Entry<K, V> entry;
 
       @Override
       public boolean hasNext() {
@@ -328,7 +344,9 @@ public Entry<K, V> next() {
 
       @Override
       public void remove() {
-        checkRemove(entry != null);
+        if (entry == null) {
+          throw new IllegalStateException("no calls to next() since the last call to remove()");
+        }
         V value = entry.getValue();
         iterator.remove();
         removeFromInverseMap(value);
@@ -352,12 +370,15 @@ public void clear() {
     }
 
     @Override
-    public boolean remove(Object object) {
-      if (!esDelegate.contains(object)) {
+    public boolean remove(@CheckForNull Object object) {
+      /*
+       * `o instanceof Entry` is guaranteed by `contains`, but we check it here to satisfy our
+       * nullness checker.
+       */
+      if (!esDelegate.contains(object) || !(object instanceof Entry)) {
         return false;
       }
 
-      // safe because esDelegate.contains(object).
       Entry<?, ?> entry = (Entry<?, ?>) object;
       inverse.delegate.remove(entry.getValue());
       /*
@@ -378,16 +399,24 @@ public Iterator<Entry<K, V>> iterator() {
 
     @Override
     public Object[] toArray() {
-      return standardToArray();
+      /*
+       * standardToArray returns `@Nullable Object[]` rather than `Object[]` but only because it can
+       * be used with collections that may contain null. This collection never contains nulls, so we
+       * can treat it as a plain `Object[]`.
+       */
+      @SuppressWarnings("nullness")
+      Object[] result = standardToArray();
+      return result;
     }
 
     @Override
-    public <T> T[] toArray(T[] array) {
+    @SuppressWarnings("nullness") // bug in our checker's handling of toArray signatures
+    public <T extends @Nullable Object> T[] toArray(T[] array) {
       return standardToArray(array);
     }
 
     @Override
-    public boolean contains(Object o) {
+    public boolean contains(@CheckForNull Object o) {
       return Maps.containsEntryImpl(delegate(), o);
     }
 
@@ -408,7 +437,8 @@ public boolean retainAll(Collection<?> c) {
   }
 
   /** The inverse of any other {@code AbstractBiMap} subclass. */
-  static class Inverse<K, V> extends AbstractBiMap<K, V> {
+  static class Inverse<K extends @Nullable Object, V extends @Nullable Object>
+      extends AbstractBiMap<K, V> {
     Inverse(Map<K, V> backward, AbstractBiMap<V, K> forward) {
       super(backward, forward);
     }
@@ -423,12 +453,14 @@ static class Inverse<K, V> extends AbstractBiMap<K, V> {
      */
 
     @Override
-    K checkKey(K key) {
+    @ParametricNullness
+    K checkKey(@ParametricNullness K key) {
       return inverse.checkValue(key);
     }
 
     @Override
-    V checkValue(V value) {
+    @ParametricNullness
+    V checkValue(@ParametricNullness V value) {
       return inverse.checkKey(value);
     }
 
diff --git a/android/guava/src/com/google/common/collect/AbstractIndexedListIterator.java b/android/guava/src/com/google/common/collect/AbstractIndexedListIterator.java
index 855fb1c5fd0b..abb3960b261e 100644
--- a/android/guava/src/com/google/common/collect/AbstractIndexedListIterator.java
+++ b/android/guava/src/com/google/common/collect/AbstractIndexedListIterator.java
@@ -21,6 +21,7 @@
 import com.google.common.annotations.GwtCompatible;
 import java.util.ListIterator;
 import java.util.NoSuchElementException;
+import org.checkerframework.checker.nullness.qual.Nullable;
 
 /**
  * This class provides a skeletal implementation of the {@link ListIterator} interface across a
@@ -30,11 +31,14 @@
  * @author Jared Levy
  */
 @GwtCompatible
-abstract class AbstractIndexedListIterator<E> extends UnmodifiableListIterator<E> {
+@ElementTypesAreNonnullByDefault
+abstract class AbstractIndexedListIterator<E extends @Nullable Object>
+    extends UnmodifiableListIterator<E> {
   private final int size;
   private int position;
 
   /** Returns the element with the specified index. This method is called by {@link #next()}. */
+  @ParametricNullness
   protected abstract E get(int index);
 
   /**
@@ -70,6 +74,7 @@ public final boolean hasNext() {
   }
 
   @Override
+  @ParametricNullness
   public final E next() {
     if (!hasNext()) {
       throw new NoSuchElementException();
@@ -88,6 +93,7 @@ public final boolean hasPrevious() {
   }
 
   @Override
+  @ParametricNullness
   public final E previous() {
     if (!hasPrevious()) {
       throw new NoSuchElementException();
diff --git a/android/guava/src/com/google/common/collect/AbstractIterator.java b/android/guava/src/com/google/common/collect/AbstractIterator.java
index ea5ea7a58326..66273f438da5 100644
--- a/android/guava/src/com/google/common/collect/AbstractIterator.java
+++ b/android/guava/src/com/google/common/collect/AbstractIterator.java
@@ -17,11 +17,13 @@
 package com.google.common.collect;
 
 import static com.google.common.base.Preconditions.checkState;
+import static com.google.common.collect.NullnessCasts.uncheckedCastNullableTToT;
 
 import com.google.common.annotations.GwtCompatible;
 import com.google.errorprone.annotations.CanIgnoreReturnValue;
 import java.util.NoSuchElementException;
-import org.checkerframework.checker.nullness.compatqual.NullableDecl;
+import javax.annotation.CheckForNull;
+import org.checkerframework.checker.nullness.qual.Nullable;
 
 /**
  * This class provides a skeletal implementation of the {@code Iterator} interface, to make this
@@ -61,7 +63,8 @@
 // When making changes to this class, please also update the copy at
 // com.google.common.base.AbstractIterator
 @GwtCompatible
-public abstract class AbstractIterator<T> extends UnmodifiableIterator<T> {
+@ElementTypesAreNonnullByDefault
+public abstract class AbstractIterator<T extends @Nullable Object> extends UnmodifiableIterator<T> {
   private State state = State.NOT_READY;
 
   /** Constructor for use by subclasses. */
@@ -81,7 +84,7 @@ private enum State {
     FAILED,
   }
 
-  @NullableDecl private T next;
+  @CheckForNull private T next;
 
   /**
    * Returns the next element. <b>Note:</b> the implementation must call {@link #endOfData()} when
@@ -107,6 +110,7 @@ private enum State {
    *     this method. Any further attempts to use the iterator will result in an {@link
    *     IllegalStateException}.
    */
+  @CheckForNull
   protected abstract T computeNext();
 
   /**
@@ -117,6 +121,7 @@ private enum State {
    *     simple statement {@code return endOfData();}
    */
   @CanIgnoreReturnValue
+  @CheckForNull
   protected final T endOfData() {
     state = State.DONE;
     return null;
@@ -148,12 +153,14 @@ private boolean tryToComputeNext() {
 
   @CanIgnoreReturnValue // TODO(kak): Should we remove this?
   @Override
+  @ParametricNullness
   public final T next() {
     if (!hasNext()) {
       throw new NoSuchElementException();
     }
     state = State.NOT_READY;
-    T result = next;
+    // Safe because hasNext() ensures that tryToComputeNext() has put a T into `next`.
+    T result = uncheckedCastNullableTToT(next);
     next = null;
     return result;
   }
@@ -165,10 +172,12 @@ public final T next() {
    * <p>Implementations of {@code AbstractIterator} that wish to expose this functionality should
    * implement {@code PeekingIterator}.
    */
+  @ParametricNullness
   public final T peek() {
     if (!hasNext()) {
       throw new NoSuchElementException();
     }
-    return next;
+    // Safe because hasNext() ensures that tryToComputeNext() has put a T into `next`.
+    return uncheckedCastNullableTToT(next);
   }
 }
diff --git a/android/guava/src/com/google/common/collect/AbstractListMultimap.java b/android/guava/src/com/google/common/collect/AbstractListMultimap.java
index 4f075d1aebb6..46c4ee2448db 100644
--- a/android/guava/src/com/google/common/collect/AbstractListMultimap.java
+++ b/android/guava/src/com/google/common/collect/AbstractListMultimap.java
@@ -22,7 +22,8 @@
 import java.util.Collections;
 import java.util.List;
 import java.util.Map;
-import org.checkerframework.checker.nullness.compatqual.NullableDecl;
+import javax.annotation.CheckForNull;
+import org.checkerframework.checker.nullness.qual.Nullable;
 
 /**
  * Basic implementation of the {@link ListMultimap} interface. It's a wrapper around {@link
@@ -33,8 +34,9 @@
  * @since 2.0
  */
 @GwtCompatible
-abstract class AbstractListMultimap<K, V> extends AbstractMapBasedMultimap<K, V>
-    implements ListMultimap<K, V> {
+@ElementTypesAreNonnullByDefault
+abstract class AbstractListMultimap<K extends @Nullable Object, V extends @Nullable Object>
+    extends AbstractMapBasedMultimap<K, V> implements ListMultimap<K, V> {
   /**
    * Creates a new multimap that uses the provided map.
    *
@@ -53,12 +55,13 @@ List<V> createUnmodifiableEmptyCollection() {
   }
 
   @Override
-  <E> Collection<E> unmodifiableCollectionSubclass(Collection<E> collection) {
+  <E extends @Nullable Object> Collection<E> unmodifiableCollectionSubclass(
+      Collection<E> collection) {
     return Collections.unmodifiableList((List<E>) collection);
   }
 
   @Override
-  Collection<V> wrapCollection(K key, Collection<V> collection) {
+  Collection<V> wrapCollection(@ParametricNullness K key, Collection<V> collection) {
     return wrapList(key, (List<V>) collection, null);
   }
 
@@ -72,7 +75,7 @@ Collection<V> wrapCollection(K key, Collection<V> collection) {
    * Multimap} interface.
    */
   @Override
-  public List<V> get(@NullableDecl K key) {
+  public List<V> get(@ParametricNullness K key) {
     return (List<V>) super.get(key);
   }
 
@@ -85,7 +88,7 @@ public List<V> get(@NullableDecl K key) {
    */
   @CanIgnoreReturnValue
   @Override
-  public List<V> removeAll(@NullableDecl Object key) {
+  public List<V> removeAll(@CheckForNull Object key) {
     return (List<V>) super.removeAll(key);
   }
 
@@ -98,7 +101,7 @@ public List<V> removeAll(@NullableDecl Object key) {
    */
   @CanIgnoreReturnValue
   @Override
-  public List<V> replaceValues(@NullableDecl K key, Iterable<? extends V> values) {
+  public List<V> replaceValues(@ParametricNullness K key, Iterable<? extends V> values) {
     return (List<V>) super.replaceValues(key, values);
   }
 
@@ -111,7 +114,7 @@ public List<V> replaceValues(@NullableDecl K key, Iterable<? extends V> values)
    */
   @CanIgnoreReturnValue
   @Override
-  public boolean put(@NullableDecl K key, @NullableDecl V value) {
+  public boolean put(@ParametricNullness K key, @ParametricNullness V value) {
     return super.put(key, value);
   }
 
@@ -133,7 +136,7 @@ public Map<K, Collection<V>> asMap() {
    * in the same order. If the value orderings disagree, the multimaps will not be considered equal.
    */
   @Override
-  public boolean equals(@NullableDecl Object object) {
+  public boolean equals(@CheckForNull Object object) {
     return super.equals(object);
   }
 
diff --git a/android/guava/src/com/google/common/collect/AbstractMapBasedMultimap.java b/android/guava/src/com/google/common/collect/AbstractMapBasedMultimap.java
index b72f13559331..72cf8f1eea5e 100644
--- a/android/guava/src/com/google/common/collect/AbstractMapBasedMultimap.java
+++ b/android/guava/src/com/google/common/collect/AbstractMapBasedMultimap.java
@@ -18,7 +18,9 @@
 
 import static com.google.common.base.Preconditions.checkArgument;
 import static com.google.common.base.Preconditions.checkNotNull;
-import static com.google.common.collect.CollectPreconditions.checkRemove;
+import static com.google.common.base.Preconditions.checkState;
+import static com.google.common.collect.NullnessCasts.uncheckedCastNullableTToT;
+import static java.util.Objects.requireNonNull;
 
 import com.google.common.annotations.GwtCompatible;
 import com.google.common.collect.Maps.ViewCachingAbstractMap;
@@ -40,7 +42,8 @@
 import java.util.Set;
 import java.util.SortedMap;
 import java.util.SortedSet;
-import org.checkerframework.checker.nullness.compatqual.NullableDecl;
+import javax.annotation.CheckForNull;
+import org.checkerframework.checker.nullness.qual.Nullable;
 
 /**
  * Basic implementation of the {@link Multimap} interface. This class represents a multimap as a map
@@ -81,8 +84,9 @@
  * @author Louis Wasserman
  */
 @GwtCompatible
-abstract class AbstractMapBasedMultimap<K, V> extends AbstractMultimap<K, V>
-    implements Serializable {
+@ElementTypesAreNonnullByDefault
+abstract class AbstractMapBasedMultimap<K extends @Nullable Object, V extends @Nullable Object>
+    extends AbstractMultimap<K, V> implements Serializable {
   /*
    * Here's an outline of the overall design.
    *
@@ -155,7 +159,7 @@ Collection<V> createUnmodifiableEmptyCollection() {
    * @param key key to associate with values in the collection
    * @return an empty collection of values
    */
-  Collection<V> createCollection(@NullableDecl K key) {
+  Collection<V> createCollection(@ParametricNullness K key) {
     return createCollection();
   }
 
@@ -171,14 +175,14 @@ public int size() {
   }
 
   @Override
-  public boolean containsKey(@NullableDecl Object key) {
+  public boolean containsKey(@CheckForNull Object key) {
     return map.containsKey(key);
   }
 
   // Modification Operations
 
   @Override
-  public boolean put(@NullableDecl K key, @NullableDecl V value) {
+  public boolean put(@ParametricNullness K key, @ParametricNullness V value) {
     Collection<V> collection = map.get(key);
     if (collection == null) {
       collection = createCollection(key);
@@ -197,7 +201,7 @@ public boolean put(@NullableDecl K key, @NullableDecl V value) {
     }
   }
 
-  private Collection<V> getOrCreateCollection(@NullableDecl K key) {
+  private Collection<V> getOrCreateCollection(@ParametricNullness K key) {
     Collection<V> collection = map.get(key);
     if (collection == null) {
       collection = createCollection(key);
@@ -214,7 +218,7 @@ private Collection<V> getOrCreateCollection(@NullableDecl K key) {
    * <p>The returned collection is immutable.
    */
   @Override
-  public Collection<V> replaceValues(@NullableDecl K key, Iterable<? extends V> values) {
+  public Collection<V> replaceValues(@ParametricNullness K key, Iterable<? extends V> values) {
     Iterator<? extends V> iterator = values.iterator();
     if (!iterator.hasNext()) {
       return removeAll(key);
@@ -243,7 +247,7 @@ public Collection<V> replaceValues(@NullableDecl K key, Iterable<? extends V> va
    * <p>The returned collection is immutable.
    */
   @Override
-  public Collection<V> removeAll(@NullableDecl Object key) {
+  public Collection<V> removeAll(@CheckForNull Object key) {
     Collection<V> collection = map.remove(key);
 
     if (collection == null) {
@@ -258,7 +262,8 @@ public Collection<V> removeAll(@NullableDecl Object key) {
     return unmodifiableCollectionSubclass(output);
   }
 
-  <E> Collection<E> unmodifiableCollectionSubclass(Collection<E> collection) {
+  <E extends @Nullable Object> Collection<E> unmodifiableCollectionSubclass(
+      Collection<E> collection) {
     return Collections.unmodifiableCollection(collection);
   }
 
@@ -280,7 +285,7 @@ public void clear() {
    * <p>The returned collection is not serializable.
    */
   @Override
-  public Collection<V> get(@NullableDecl K key) {
+  public Collection<V> get(@ParametricNullness K key) {
     Collection<V> collection = map.get(key);
     if (collection == null) {
       collection = createCollection(key);
@@ -292,12 +297,12 @@ public Collection<V> get(@NullableDecl K key) {
    * Generates a decorated collection that remains consistent with the values in the multimap for
    * the provided key. Changes to the multimap may alter the returned collection, and vice versa.
    */
-  Collection<V> wrapCollection(@NullableDecl K key, Collection<V> collection) {
+  Collection<V> wrapCollection(@ParametricNullness K key, Collection<V> collection) {
     return new WrappedCollection(key, collection, null);
   }
 
   final List<V> wrapList(
-      @NullableDecl K key, List<V> list, @NullableDecl WrappedCollection ancestor) {
+      @ParametricNullness K key, List<V> list, @CheckForNull WrappedCollection ancestor) {
     return (list instanceof RandomAccess)
         ? new RandomAccessWrappedList(key, list, ancestor)
         : new WrappedList(key, list, ancestor);
@@ -320,13 +325,15 @@ final List<V> wrapList(
    */
   @WeakOuter
   class WrappedCollection extends AbstractCollection<V> {
-    @NullableDecl final K key;
+    @ParametricNullness final K key;
     Collection<V> delegate;
-    @NullableDecl final WrappedCollection ancestor;
-    @NullableDecl final Collection<V> ancestorDelegate;
+    @CheckForNull final WrappedCollection ancestor;
+    @CheckForNull final Collection<V> ancestorDelegate;
 
     WrappedCollection(
-        @NullableDecl K key, Collection<V> delegate, @NullableDecl WrappedCollection ancestor) {
+        @ParametricNullness K key,
+        Collection<V> delegate,
+        @CheckForNull WrappedCollection ancestor) {
       this.key = key;
       this.delegate = delegate;
       this.ancestor = ancestor;
@@ -366,6 +373,7 @@ void removeIfEmpty() {
       }
     }
 
+    @ParametricNullness
     K getKey() {
       return key;
     }
@@ -391,7 +399,7 @@ public int size() {
     }
 
     @Override
-    public boolean equals(@NullableDecl Object object) {
+    public boolean equals(@CheckForNull Object object) {
       if (object == this) {
         return true;
       }
@@ -451,6 +459,7 @@ public boolean hasNext() {
       }
 
       @Override
+      @ParametricNullness
       public V next() {
         validateIterator();
         return delegateIterator.next();
@@ -470,7 +479,7 @@ Iterator<V> getDelegateIterator() {
     }
 
     @Override
-    public boolean add(V value) {
+    public boolean add(@ParametricNullness V value) {
       refreshIfEmpty();
       boolean wasEmpty = delegate.isEmpty();
       boolean changed = delegate.add(value);
@@ -483,6 +492,7 @@ public boolean add(V value) {
       return changed;
     }
 
+    @CheckForNull
     WrappedCollection getAncestor() {
       return ancestor;
     }
@@ -507,7 +517,7 @@ public boolean addAll(Collection<? extends V> collection) {
     }
 
     @Override
-    public boolean contains(Object o) {
+    public boolean contains(@CheckForNull Object o) {
       refreshIfEmpty();
       return delegate.contains(o);
     }
@@ -530,7 +540,7 @@ public void clear() {
     }
 
     @Override
-    public boolean remove(Object o) {
+    public boolean remove(@CheckForNull Object o) {
       refreshIfEmpty();
       boolean changed = delegate.remove(o);
       if (changed) {
@@ -569,7 +579,8 @@ public boolean retainAll(Collection<?> c) {
     }
   }
 
-  private static <E> Iterator<E> iteratorOrListIterator(Collection<E> collection) {
+  private static <E extends @Nullable Object> Iterator<E> iteratorOrListIterator(
+      Collection<E> collection) {
     return (collection instanceof List)
         ? ((List<E>) collection).listIterator()
         : collection.iterator();
@@ -578,7 +589,7 @@ private static <E> Iterator<E> iteratorOrListIterator(Collection<E> collection)
   /** Set decorator that stays in sync with the multimap values for a key. */
   @WeakOuter
   class WrappedSet extends WrappedCollection implements Set<V> {
-    WrappedSet(@NullableDecl K key, Set<V> delegate) {
+    WrappedSet(@ParametricNullness K key, Set<V> delegate) {
       super(key, delegate, null);
     }
 
@@ -606,7 +617,9 @@ public boolean removeAll(Collection<?> c) {
   @WeakOuter
   class WrappedSortedSet extends WrappedCollection implements SortedSet<V> {
     WrappedSortedSet(
-        @NullableDecl K key, SortedSet<V> delegate, @NullableDecl WrappedCollection ancestor) {
+        @ParametricNullness K key,
+        SortedSet<V> delegate,
+        @CheckForNull WrappedCollection ancestor) {
       super(key, delegate, ancestor);
     }
 
@@ -615,24 +628,27 @@ SortedSet<V> getSortedSetDelegate() {
     }
 
     @Override
+    @CheckForNull
     public Comparator<? super V> comparator() {
       return getSortedSetDelegate().comparator();
     }
 
     @Override
+    @ParametricNullness
     public V first() {
       refreshIfEmpty();
       return getSortedSetDelegate().first();
     }
 
     @Override
+    @ParametricNullness
     public V last() {
       refreshIfEmpty();
       return getSortedSetDelegate().last();
     }
 
     @Override
-    public SortedSet<V> headSet(V toElement) {
+    public SortedSet<V> headSet(@ParametricNullness V toElement) {
       refreshIfEmpty();
       return new WrappedSortedSet(
           getKey(),
@@ -641,7 +657,7 @@ public SortedSet<V> headSet(V toElement) {
     }
 
     @Override
-    public SortedSet<V> subSet(V fromElement, V toElement) {
+    public SortedSet<V> subSet(@ParametricNullness V fromElement, @ParametricNullness V toElement) {
       refreshIfEmpty();
       return new WrappedSortedSet(
           getKey(),
@@ -650,7 +666,7 @@ public SortedSet<V> subSet(V fromElement, V toElement) {
     }
 
     @Override
-    public SortedSet<V> tailSet(V fromElement) {
+    public SortedSet<V> tailSet(@ParametricNullness V fromElement) {
       refreshIfEmpty();
       return new WrappedSortedSet(
           getKey(),
@@ -662,7 +678,9 @@ public SortedSet<V> tailSet(V fromElement) {
   @WeakOuter
   class WrappedNavigableSet extends WrappedSortedSet implements NavigableSet<V> {
     WrappedNavigableSet(
-        @NullableDecl K key, NavigableSet<V> delegate, @NullableDecl WrappedCollection ancestor) {
+        @ParametricNullness K key,
+        NavigableSet<V> delegate,
+        @CheckForNull WrappedCollection ancestor) {
       super(key, delegate, ancestor);
     }
 
@@ -672,31 +690,37 @@ NavigableSet<V> getSortedSetDelegate() {
     }
 
     @Override
-    public V lower(V v) {
+    @CheckForNull
+    public V lower(@ParametricNullness V v) {
       return getSortedSetDelegate().lower(v);
     }
 
     @Override
-    public V floor(V v) {
+    @CheckForNull
+    public V floor(@ParametricNullness V v) {
       return getSortedSetDelegate().floor(v);
     }
 
     @Override
-    public V ceiling(V v) {
+    @CheckForNull
+    public V ceiling(@ParametricNullness V v) {
       return getSortedSetDelegate().ceiling(v);
     }
 
     @Override
-    public V higher(V v) {
+    @CheckForNull
+    public V higher(@ParametricNullness V v) {
       return getSortedSetDelegate().higher(v);
     }
 
     @Override
+    @CheckForNull
     public V pollFirst() {
       return Iterators.pollNext(iterator());
     }
 
     @Override
+    @CheckForNull
     public V pollLast() {
       return Iterators.pollNext(descendingIterator());
     }
@@ -717,18 +741,21 @@ public Iterator<V> descendingIterator() {
 
     @Override
     public NavigableSet<V> subSet(
-        V fromElement, boolean fromInclusive, V toElement, boolean toInclusive) {
+        @ParametricNullness V fromElement,
+        boolean fromInclusive,
+        @ParametricNullness V toElement,
+        boolean toInclusive) {
       return wrap(
           getSortedSetDelegate().subSet(fromElement, fromInclusive, toElement, toInclusive));
     }
 
     @Override
-    public NavigableSet<V> headSet(V toElement, boolean inclusive) {
+    public NavigableSet<V> headSet(@ParametricNullness V toElement, boolean inclusive) {
       return wrap(getSortedSetDelegate().headSet(toElement, inclusive));
     }
 
     @Override
-    public NavigableSet<V> tailSet(V fromElement, boolean inclusive) {
+    public NavigableSet<V> tailSet(@ParametricNullness V fromElement, boolean inclusive) {
       return wrap(getSortedSetDelegate().tailSet(fromElement, inclusive));
     }
   }
@@ -736,7 +763,8 @@ public NavigableSet<V> tailSet(V fromElement, boolean inclusive) {
   /** List decorator that stays in sync with the multimap values for a key. */
   @WeakOuter
   class WrappedList extends WrappedCollection implements List<V> {
-    WrappedList(@NullableDecl K key, List<V> delegate, @NullableDecl WrappedCollection ancestor) {
+    WrappedList(
+        @ParametricNullness K key, List<V> delegate, @CheckForNull WrappedCollection ancestor) {
       super(key, delegate, ancestor);
     }
 
@@ -762,19 +790,21 @@ public boolean addAll(int index, Collection<? extends V> c) {
     }
 
     @Override
+    @ParametricNullness
     public V get(int index) {
       refreshIfEmpty();
       return getListDelegate().get(index);
     }
 
     @Override
-    public V set(int index, V element) {
+    @ParametricNullness
+    public V set(int index, @ParametricNullness V element) {
       refreshIfEmpty();
       return getListDelegate().set(index, element);
     }
 
     @Override
-    public void add(int index, V element) {
+    public void add(int index, @ParametricNullness V element) {
       refreshIfEmpty();
       boolean wasEmpty = getDelegate().isEmpty();
       getListDelegate().add(index, element);
@@ -785,6 +815,7 @@ public void add(int index, V element) {
     }
 
     @Override
+    @ParametricNullness
     public V remove(int index) {
       refreshIfEmpty();
       V value = getListDelegate().remove(index);
@@ -794,13 +825,13 @@ public V remove(int index) {
     }
 
     @Override
-    public int indexOf(Object o) {
+    public int indexOf(@CheckForNull Object o) {
       refreshIfEmpty();
       return getListDelegate().indexOf(o);
     }
 
     @Override
-    public int lastIndexOf(Object o) {
+    public int lastIndexOf(@CheckForNull Object o) {
       refreshIfEmpty();
       return getListDelegate().lastIndexOf(o);
     }
@@ -844,6 +875,7 @@ public boolean hasPrevious() {
       }
 
       @Override
+      @ParametricNullness
       public V previous() {
         return getDelegateListIterator().previous();
       }
@@ -859,12 +891,12 @@ public int previousIndex() {
       }
 
       @Override
-      public void set(V value) {
+      public void set(@ParametricNullness V value) {
         getDelegateListIterator().set(value);
       }
 
       @Override
-      public void add(V value) {
+      public void add(@ParametricNullness V value) {
         boolean wasEmpty = isEmpty();
         getDelegateListIterator().add(value);
         totalSize++;
@@ -881,7 +913,7 @@ public void add(V value) {
    */
   private class RandomAccessWrappedList extends WrappedList implements RandomAccess {
     RandomAccessWrappedList(
-        @NullableDecl K key, List<V> delegate, @NullableDecl WrappedCollection ancestor) {
+        @ParametricNullness K key, List<V> delegate, @CheckForNull WrappedCollection ancestor) {
       super(key, delegate, ancestor);
     }
   }
@@ -911,7 +943,7 @@ private class KeySet extends Maps.KeySet<K, Collection<V>> {
     public Iterator<K> iterator() {
       final Iterator<Entry<K, Collection<V>>> entryIterator = map().entrySet().iterator();
       return new Iterator<K>() {
-        @NullableDecl Entry<K, Collection<V>> entry;
+        @CheckForNull Entry<K, Collection<V>> entry;
 
         @Override
         public boolean hasNext() {
@@ -919,6 +951,7 @@ public boolean hasNext() {
         }
 
         @Override
+        @ParametricNullness
         public K next() {
           entry = entryIterator.next();
           return entry.getKey();
@@ -926,7 +959,7 @@ public K next() {
 
         @Override
         public void remove() {
-          checkRemove(entry != null);
+          checkState(entry != null, "no calls to next() since the last call to remove()");
           Collection<V> collection = entry.getValue();
           entryIterator.remove();
           totalSize -= collection.size();
@@ -939,7 +972,7 @@ public void remove() {
     // The following methods are included for better performance.
 
     @Override
-    public boolean remove(Object key) {
+    public boolean remove(@CheckForNull Object key) {
       int count = 0;
       Collection<V> collection = map().remove(key);
       if (collection != null) {
@@ -961,7 +994,7 @@ public boolean containsAll(Collection<?> c) {
     }
 
     @Override
-    public boolean equals(@NullableDecl Object object) {
+    public boolean equals(@CheckForNull Object object) {
       return this == object || this.map().keySet().equals(object);
     }
 
@@ -983,32 +1016,35 @@ SortedMap<K, Collection<V>> sortedMap() {
     }
 
     @Override
+    @CheckForNull
     public Comparator<? super K> comparator() {
       return sortedMap().comparator();
     }
 
     @Override
+    @ParametricNullness
     public K first() {
       return sortedMap().firstKey();
     }
 
     @Override
-    public SortedSet<K> headSet(K toElement) {
+    public SortedSet<K> headSet(@ParametricNullness K toElement) {
       return new SortedKeySet(sortedMap().headMap(toElement));
     }
 
     @Override
+    @ParametricNullness
     public K last() {
       return sortedMap().lastKey();
     }
 
     @Override
-    public SortedSet<K> subSet(K fromElement, K toElement) {
+    public SortedSet<K> subSet(@ParametricNullness K fromElement, @ParametricNullness K toElement) {
       return new SortedKeySet(sortedMap().subMap(fromElement, toElement));
     }
 
     @Override
-    public SortedSet<K> tailSet(K fromElement) {
+    public SortedSet<K> tailSet(@ParametricNullness K fromElement) {
       return new SortedKeySet(sortedMap().tailMap(fromElement));
     }
   }
@@ -1025,31 +1061,37 @@ NavigableMap<K, Collection<V>> sortedMap() {
     }
 
     @Override
-    public K lower(K k) {
+    @CheckForNull
+    public K lower(@ParametricNullness K k) {
       return sortedMap().lowerKey(k);
     }
 
     @Override
-    public K floor(K k) {
+    @CheckForNull
+    public K floor(@ParametricNullness K k) {
       return sortedMap().floorKey(k);
     }
 
     @Override
-    public K ceiling(K k) {
+    @CheckForNull
+    public K ceiling(@ParametricNullness K k) {
       return sortedMap().ceilingKey(k);
     }
 
     @Override
-    public K higher(K k) {
+    @CheckForNull
+    public K higher(@ParametricNullness K k) {
       return sortedMap().higherKey(k);
     }
 
     @Override
+    @CheckForNull
     public K pollFirst() {
       return Iterators.pollNext(iterator());
     }
 
     @Override
+    @CheckForNull
     public K pollLast() {
       return Iterators.pollNext(descendingIterator());
     }
@@ -1065,40 +1107,44 @@ public Iterator<K> descendingIterator() {
     }
 
     @Override
-    public NavigableSet<K> headSet(K toElement) {
+    public NavigableSet<K> headSet(@ParametricNullness K toElement) {
       return headSet(toElement, false);
     }
 
     @Override
-    public NavigableSet<K> headSet(K toElement, boolean inclusive) {
+    public NavigableSet<K> headSet(@ParametricNullness K toElement, boolean inclusive) {
       return new NavigableKeySet(sortedMap().headMap(toElement, inclusive));
     }
 
     @Override
-    public NavigableSet<K> subSet(K fromElement, K toElement) {
+    public NavigableSet<K> subSet(
+        @ParametricNullness K fromElement, @ParametricNullness K toElement) {
       return subSet(fromElement, true, toElement, false);
     }
 
     @Override
     public NavigableSet<K> subSet(
-        K fromElement, boolean fromInclusive, K toElement, boolean toInclusive) {
+        @ParametricNullness K fromElement,
+        boolean fromInclusive,
+        @ParametricNullness K toElement,
+        boolean toInclusive) {
       return new NavigableKeySet(
           sortedMap().subMap(fromElement, fromInclusive, toElement, toInclusive));
     }
 
     @Override
-    public NavigableSet<K> tailSet(K fromElement) {
+    public NavigableSet<K> tailSet(@ParametricNullness K fromElement) {
       return tailSet(fromElement, true);
     }
 
     @Override
-    public NavigableSet<K> tailSet(K fromElement, boolean inclusive) {
+    public NavigableSet<K> tailSet(@ParametricNullness K fromElement, boolean inclusive) {
       return new NavigableKeySet(sortedMap().tailMap(fromElement, inclusive));
     }
   }
 
   /** Removes all values for the provided key. */
-  private void removeValuesForKey(Object key) {
+  private void removeValuesForKey(@CheckForNull Object key) {
     Collection<V> collection = Maps.safeRemove(map, key);
 
     if (collection != null) {
@@ -1108,10 +1154,10 @@ private void removeValuesForKey(Object key) {
     }
   }
 
-  private abstract class Itr<T> implements Iterator<T> {
+  private abstract class Itr<T extends @Nullable Object> implements Iterator<T> {
     final Iterator<Entry<K, Collection<V>>> keyIterator;
-    @NullableDecl K key;
-    @NullableDecl Collection<V> collection;
+    @CheckForNull K key;
+    @CheckForNull Collection<V> collection;
     Iterator<V> valueIterator;
 
     Itr() {
@@ -1121,7 +1167,7 @@ private abstract class Itr<T> implements Iterator<T> {
       valueIterator = Iterators.emptyModifiableIterator();
     }
 
-    abstract T output(K key, V value);
+    abstract T output(@ParametricNullness K key, @ParametricNullness V value);
 
     @Override
     public boolean hasNext() {
@@ -1136,13 +1182,21 @@ public T next() {
         collection = mapEntry.getValue();
         valueIterator = collection.iterator();
       }
-      return output(key, valueIterator.next());
+      /*
+       * uncheckedCastNullableTToT is safe: The first call to this method always enters the !hasNext() case and
+       * populates key, after which it's never cleared.
+       */
+      return output(uncheckedCastNullableTToT(key), valueIterator.next());
     }
 
     @Override
     public void remove() {
       valueIterator.remove();
-      if (collection.isEmpty()) {
+      /*
+       * requireNonNull is safe because we've already initialized `collection`. If we hadn't, then
+       * valueIterator.remove() would have failed.
+       */
+      if (requireNonNull(collection).isEmpty()) {
         keyIterator.remove();
       }
       totalSize--;
@@ -1169,7 +1223,8 @@ Collection<V> createValues() {
   Iterator<V> valueIterator() {
     return new Itr<V>() {
       @Override
-      V output(K key, V value) {
+      @ParametricNullness
+      V output(@ParametricNullness K key, @ParametricNullness V value) {
         return value;
       }
     };
@@ -1221,7 +1276,7 @@ Collection<Entry<K, V>> createEntries() {
   Iterator<Entry<K, V>> entryIterator() {
     return new Itr<Entry<K, V>>() {
       @Override
-      Entry<K, V> output(K key, V value) {
+      Entry<K, V> output(@ParametricNullness K key, @ParametricNullness V value) {
         return Maps.immutableEntry(key, value);
       }
     };
@@ -1262,12 +1317,13 @@ protected Set<Entry<K, Collection<V>>> createEntrySet() {
     // The following methods are included for performance.
 
     @Override
-    public boolean containsKey(Object key) {
+    public boolean containsKey(@CheckForNull Object key) {
       return Maps.safeContainsKey(submap, key);
     }
 
     @Override
-    public Collection<V> get(Object key) {
+    @CheckForNull
+    public Collection<V> get(@CheckForNull Object key) {
       Collection<V> collection = Maps.safeGet(submap, key);
       if (collection == null) {
         return null;
@@ -1288,7 +1344,8 @@ public int size() {
     }
 
     @Override
-    public Collection<V> remove(Object key) {
+    @CheckForNull
+    public Collection<V> remove(@CheckForNull Object key) {
       Collection<V> collection = submap.remove(key);
       if (collection == null) {
         return null;
@@ -1302,7 +1359,7 @@ public Collection<V> remove(Object key) {
     }
 
     @Override
-    public boolean equals(@NullableDecl Object object) {
+    public boolean equals(@CheckForNull Object object) {
       return this == object || submap.equals(object);
     }
 
@@ -1345,16 +1402,17 @@ public Iterator<Entry<K, Collection<V>>> iterator() {
       // The following methods are included for performance.
 
       @Override
-      public boolean contains(Object o) {
+      public boolean contains(@CheckForNull Object o) {
         return Collections2.safeContains(submap.entrySet(), o);
       }
 
       @Override
-      public boolean remove(Object o) {
+      public boolean remove(@CheckForNull Object o) {
         if (!contains(o)) {
           return false;
         }
-        Entry<?, ?> entry = (Entry<?, ?>) o;
+        // requireNonNull is safe because of the contains check.
+        Entry<?, ?> entry = requireNonNull((Entry<?, ?>) o);
         removeValuesForKey(entry.getKey());
         return true;
       }
@@ -1363,7 +1421,7 @@ public boolean remove(Object o) {
     /** Iterator across all keys and value collections. */
     class AsMapIterator implements Iterator<Entry<K, Collection<V>>> {
       final Iterator<Entry<K, Collection<V>>> delegateIterator = submap.entrySet().iterator();
-      @NullableDecl Collection<V> collection;
+      @CheckForNull Collection<V> collection;
 
       @Override
       public boolean hasNext() {
@@ -1379,7 +1437,7 @@ public Entry<K, Collection<V>> next() {
 
       @Override
       public void remove() {
-        checkRemove(collection != null);
+        checkState(collection != null, "no calls to next() since the last call to remove()");
         delegateIterator.remove();
         totalSize -= collection.size();
         collection.clear();
@@ -1399,36 +1457,40 @@ SortedMap<K, Collection<V>> sortedMap() {
     }
 
     @Override
+    @CheckForNull
     public Comparator<? super K> comparator() {
       return sortedMap().comparator();
     }
 
     @Override
+    @ParametricNullness
     public K firstKey() {
       return sortedMap().firstKey();
     }
 
     @Override
+    @ParametricNullness
     public K lastKey() {
       return sortedMap().lastKey();
     }
 
     @Override
-    public SortedMap<K, Collection<V>> headMap(K toKey) {
+    public SortedMap<K, Collection<V>> headMap(@ParametricNullness K toKey) {
       return new SortedAsMap(sortedMap().headMap(toKey));
     }
 
     @Override
-    public SortedMap<K, Collection<V>> subMap(K fromKey, K toKey) {
+    public SortedMap<K, Collection<V>> subMap(
+        @ParametricNullness K fromKey, @ParametricNullness K toKey) {
       return new SortedAsMap(sortedMap().subMap(fromKey, toKey));
     }
 
     @Override
-    public SortedMap<K, Collection<V>> tailMap(K fromKey) {
+    public SortedMap<K, Collection<V>> tailMap(@ParametricNullness K fromKey) {
       return new SortedAsMap(sortedMap().tailMap(fromKey));
     }
 
-    @NullableDecl SortedSet<K> sortedKeySet;
+    @CheckForNull SortedSet<K> sortedKeySet;
 
     // returns a SortedSet, even though returning a Set would be sufficient to
     // satisfy the SortedMap.keySet() interface
@@ -1456,71 +1518,84 @@ NavigableMap<K, Collection<V>> sortedMap() {
     }
 
     @Override
-    public Entry<K, Collection<V>> lowerEntry(K key) {
+    @CheckForNull
+    public Entry<K, Collection<V>> lowerEntry(@ParametricNullness K key) {
       Entry<K, Collection<V>> entry = sortedMap().lowerEntry(key);
       return (entry == null) ? null : wrapEntry(entry);
     }
 
     @Override
-    public K lowerKey(K key) {
+    @CheckForNull
+    public K lowerKey(@ParametricNullness K key) {
       return sortedMap().lowerKey(key);
     }
 
     @Override
-    public Entry<K, Collection<V>> floorEntry(K key) {
+    @CheckForNull
+    public Entry<K, Collection<V>> floorEntry(@ParametricNullness K key) {
       Entry<K, Collection<V>> entry = sortedMap().floorEntry(key);
       return (entry == null) ? null : wrapEntry(entry);
     }
 
     @Override
-    public K floorKey(K key) {
+    @CheckForNull
+    public K floorKey(@ParametricNullness K key) {
       return sortedMap().floorKey(key);
     }
 
     @Override
-    public Entry<K, Collection<V>> ceilingEntry(K key) {
+    @CheckForNull
+    public Entry<K, Collection<V>> ceilingEntry(@ParametricNullness K key) {
       Entry<K, Collection<V>> entry = sortedMap().ceilingEntry(key);
       return (entry == null) ? null : wrapEntry(entry);
     }
 
     @Override
-    public K ceilingKey(K key) {
+    @CheckForNull
+    public K ceilingKey(@ParametricNullness K key) {
       return sortedMap().ceilingKey(key);
     }
 
     @Override
-    public Entry<K, Collection<V>> higherEntry(K key) {
+    @CheckForNull
+    public Entry<K, Collection<V>> higherEntry(@ParametricNullness K key) {
       Entry<K, Collection<V>> entry = sortedMap().higherEntry(key);
       return (entry == null) ? null : wrapEntry(entry);
     }
 
     @Override
-    public K higherKey(K key) {
+    @CheckForNull
+    public K higherKey(@ParametricNullness K key) {
       return sortedMap().higherKey(key);
     }
 
     @Override
+    @CheckForNull
     public Entry<K, Collection<V>> firstEntry() {
       Entry<K, Collection<V>> entry = sortedMap().firstEntry();
       return (entry == null) ? null : wrapEntry(entry);
     }
 
     @Override
+    @CheckForNull
     public Entry<K, Collection<V>> lastEntry() {
       Entry<K, Collection<V>> entry = sortedMap().lastEntry();
       return (entry == null) ? null : wrapEntry(entry);
     }
 
     @Override
+    @CheckForNull
     public Entry<K, Collection<V>> pollFirstEntry() {
       return pollAsMapEntry(entrySet().iterator());
     }
 
     @Override
+    @CheckForNull
     public Entry<K, Collection<V>> pollLastEntry() {
       return pollAsMapEntry(descendingMap().entrySet().iterator());
     }
 
+    @CheckForNull
     Entry<K, Collection<V>> pollAsMapEntry(Iterator<Entry<K, Collection<V>>> entryIterator) {
       if (!entryIterator.hasNext()) {
         return null;
@@ -1558,33 +1633,38 @@ public NavigableSet<K> descendingKeySet() {
     }
 
     @Override
-    public NavigableMap<K, Collection<V>> subMap(K fromKey, K toKey) {
+    public NavigableMap<K, Collection<V>> subMap(
+        @ParametricNullness K fromKey, @ParametricNullness K toKey) {
       return subMap(fromKey, true, toKey, false);
     }
 
     @Override
     public NavigableMap<K, Collection<V>> subMap(
-        K fromKey, boolean fromInclusive, K toKey, boolean toInclusive) {
+        @ParametricNullness K fromKey,
+        boolean fromInclusive,
+        @ParametricNullness K toKey,
+        boolean toInclusive) {
       return new NavigableAsMap(sortedMap().subMap(fromKey, fromInclusive, toKey, toInclusive));
     }
 
     @Override
-    public NavigableMap<K, Collection<V>> headMap(K toKey) {
+    public NavigableMap<K, Collection<V>> headMap(@ParametricNullness K toKey) {
       return headMap(toKey, false);
     }
 
     @Override
-    public NavigableMap<K, Collection<V>> headMap(K toKey, boolean inclusive) {
+    public NavigableMap<K, Collection<V>> headMap(@ParametricNullness K toKey, boolean inclusive) {
       return new NavigableAsMap(sortedMap().headMap(toKey, inclusive));
     }
 
     @Override
-    public NavigableMap<K, Collection<V>> tailMap(K fromKey) {
+    public NavigableMap<K, Collection<V>> tailMap(@ParametricNullness K fromKey) {
       return tailMap(fromKey, true);
     }
 
     @Override
-    public NavigableMap<K, Collection<V>> tailMap(K fromKey, boolean inclusive) {
+    public NavigableMap<K, Collection<V>> tailMap(
+        @ParametricNullness K fromKey, boolean inclusive) {
       return new NavigableAsMap(sortedMap().tailMap(fromKey, inclusive));
     }
   }
diff --git a/android/guava/src/com/google/common/collect/AbstractMapBasedMultiset.java b/android/guava/src/com/google/common/collect/AbstractMapBasedMultiset.java
index 3ff472a9fc25..8c71e682da31 100644
--- a/android/guava/src/com/google/common/collect/AbstractMapBasedMultiset.java
+++ b/android/guava/src/com/google/common/collect/AbstractMapBasedMultiset.java
@@ -31,11 +31,12 @@
 import java.util.ConcurrentModificationException;
 import java.util.Iterator;
 import java.util.NoSuchElementException;
-import org.checkerframework.checker.nullness.compatqual.NullableDecl;
+import javax.annotation.CheckForNull;
+import org.checkerframework.checker.nullness.qual.Nullable;
 
 /**
  * Basic implementation of {@code Multiset<E>} backed by an instance of {@code
- * AbstractObjectCountMap<E>}.
+ * ObjectCountHashMap<E>}.
  *
  * <p>For serialization to work, the subclass must specify explicit {@code readObject} and {@code
  * writeObject} methods.
@@ -43,19 +44,21 @@
  * @author Kevin Bourrillion
  */
 @GwtCompatible(emulated = true)
-abstract class AbstractMapBasedMultiset<E> extends AbstractMultiset<E> implements Serializable {
+@ElementTypesAreNonnullByDefault
+abstract class AbstractMapBasedMultiset<E extends @Nullable Object> extends AbstractMultiset<E>
+    implements Serializable {
 
   transient ObjectCountHashMap<E> backingMap;
   transient long size;
 
   AbstractMapBasedMultiset(int distinctElements) {
-    init(distinctElements);
+    backingMap = newBackingMap(distinctElements);
   }
 
-  abstract void init(int distinctElements);
+  abstract ObjectCountHashMap<E> newBackingMap(int distinctElements);
 
   @Override
-  public final int count(@NullableDecl Object element) {
+  public final int count(@CheckForNull Object element) {
     return backingMap.get(element);
   }
 
@@ -69,7 +72,7 @@ public final int count(@NullableDecl Object element) {
    */
   @CanIgnoreReturnValue
   @Override
-  public final int add(@NullableDecl E element, int occurrences) {
+  public final int add(@ParametricNullness E element, int occurrences) {
     if (occurrences == 0) {
       return count(element);
     }
@@ -90,7 +93,7 @@ public final int add(@NullableDecl E element, int occurrences) {
 
   @CanIgnoreReturnValue
   @Override
-  public final int remove(@NullableDecl Object element, int occurrences) {
+  public final int remove(@CheckForNull Object element, int occurrences) {
     if (occurrences == 0) {
       return count(element);
     }
@@ -114,7 +117,7 @@ public final int remove(@NullableDecl Object element, int occurrences) {
 
   @CanIgnoreReturnValue
   @Override
-  public final int setCount(@NullableDecl E element, int count) {
+  public final int setCount(@ParametricNullness E element, int count) {
     checkNonnegative(count, "count");
     int oldCount = (count == 0) ? backingMap.remove(element) : backingMap.put(element, count);
     size += (count - oldCount);
@@ -122,7 +125,7 @@ public final int setCount(@NullableDecl E element, int count) {
   }
 
   @Override
-  public final boolean setCount(@NullableDecl E element, int oldCount, int newCount) {
+  public final boolean setCount(@ParametricNullness E element, int oldCount, int newCount) {
     checkNonnegative(oldCount, "oldCount");
     checkNonnegative(newCount, "newCount");
     int entryIndex = backingMap.indexOf(element);
@@ -160,11 +163,12 @@ public final void clear() {
    * Skeleton of per-entry iterators. We could push this down and win a few bytes, but it's complex
    * enough it's not especially worth it.
    */
-  abstract class Itr<T> implements Iterator<T> {
+  abstract class Itr<T extends @Nullable Object> implements Iterator<T> {
     int entryIndex = backingMap.firstIndex();
     int toRemove = -1;
     int expectedModCount = backingMap.modCount;
 
+    @ParametricNullness
     abstract T result(int entryIndex);
 
     private void checkForConcurrentModification() {
@@ -180,6 +184,7 @@ public boolean hasNext() {
     }
 
     @Override
+    @ParametricNullness
     public T next() {
       if (!hasNext()) {
         throw new NoSuchElementException();
@@ -205,6 +210,7 @@ public void remove() {
   final Iterator<E> elementIterator() {
     return new Itr<E>() {
       @Override
+      @ParametricNullness
       E result(int entryIndex) {
         return backingMap.getKey(entryIndex);
       }
@@ -258,7 +264,7 @@ private void writeObject(ObjectOutputStream stream) throws IOException {
   private void readObject(ObjectInputStream stream) throws IOException, ClassNotFoundException {
     stream.defaultReadObject();
     int distinctElements = Serialization.readCount(stream);
-    init(ObjectCountHashMap.DEFAULT_SIZE);
+    backingMap = newBackingMap(ObjectCountHashMap.DEFAULT_SIZE);
     Serialization.populateMultiset(this, stream, distinctElements);
   }
 
diff --git a/android/guava/src/com/google/common/collect/AbstractMapEntry.java b/android/guava/src/com/google/common/collect/AbstractMapEntry.java
index 27ea432ba3de..e9accf0592c2 100644
--- a/android/guava/src/com/google/common/collect/AbstractMapEntry.java
+++ b/android/guava/src/com/google/common/collect/AbstractMapEntry.java
@@ -19,7 +19,8 @@
 import com.google.common.annotations.GwtCompatible;
 import com.google.common.base.Objects;
 import java.util.Map.Entry;
-import org.checkerframework.checker.nullness.compatqual.NullableDecl;
+import javax.annotation.CheckForNull;
+import org.checkerframework.checker.nullness.qual.Nullable;
 
 /**
  * Implementation of the {@code equals}, {@code hashCode}, and {@code toString} methods of {@code
@@ -28,21 +29,26 @@
  * @author Jared Levy
  */
 @GwtCompatible
-abstract class AbstractMapEntry<K, V> implements Entry<K, V> {
+@ElementTypesAreNonnullByDefault
+abstract class AbstractMapEntry<K extends @Nullable Object, V extends @Nullable Object>
+    implements Entry<K, V> {
 
   @Override
+  @ParametricNullness
   public abstract K getKey();
 
   @Override
+  @ParametricNullness
   public abstract V getValue();
 
   @Override
-  public V setValue(V value) {
+  @ParametricNullness
+  public V setValue(@ParametricNullness V value) {
     throw new UnsupportedOperationException();
   }
 
   @Override
-  public boolean equals(@NullableDecl Object object) {
+  public boolean equals(@CheckForNull Object object) {
     if (object instanceof Entry) {
       Entry<?, ?> that = (Entry<?, ?>) object;
       return Objects.equal(this.getKey(), that.getKey())
diff --git a/android/guava/src/com/google/common/collect/AbstractMultimap.java b/android/guava/src/com/google/common/collect/AbstractMultimap.java
index a9952172d104..17e84a62a855 100644
--- a/android/guava/src/com/google/common/collect/AbstractMultimap.java
+++ b/android/guava/src/com/google/common/collect/AbstractMultimap.java
@@ -28,7 +28,8 @@
 import java.util.Map;
 import java.util.Map.Entry;
 import java.util.Set;
-import org.checkerframework.checker.nullness.compatqual.NullableDecl;
+import javax.annotation.CheckForNull;
+import org.checkerframework.checker.nullness.qual.Nullable;
 
 /**
  * A skeleton {@code Multimap} implementation, not necessarily in terms of a {@code Map}.
@@ -36,14 +37,16 @@
  * @author Louis Wasserman
  */
 @GwtCompatible
-abstract class AbstractMultimap<K, V> implements Multimap<K, V> {
+@ElementTypesAreNonnullByDefault
+abstract class AbstractMultimap<K extends @Nullable Object, V extends @Nullable Object>
+    implements Multimap<K, V> {
   @Override
   public boolean isEmpty() {
     return size() == 0;
   }
 
   @Override
-  public boolean containsValue(@NullableDecl Object value) {
+  public boolean containsValue(@CheckForNull Object value) {
     for (Collection<V> collection : asMap().values()) {
       if (collection.contains(value)) {
         return true;
@@ -54,27 +57,27 @@ public boolean containsValue(@NullableDecl Object value) {
   }
 
   @Override
-  public boolean containsEntry(@NullableDecl Object key, @NullableDecl Object value) {
+  public boolean containsEntry(@CheckForNull Object key, @CheckForNull Object value) {
     Collection<V> collection = asMap().get(key);
     return collection != null && collection.contains(value);
   }
 
   @CanIgnoreReturnValue
   @Override
-  public boolean remove(@NullableDecl Object key, @NullableDecl Object value) {
+  public boolean remove(@CheckForNull Object key, @CheckForNull Object value) {
     Collection<V> collection = asMap().get(key);
     return collection != null && collection.remove(value);
   }
 
   @CanIgnoreReturnValue
   @Override
-  public boolean put(@NullableDecl K key, @NullableDecl V value) {
+  public boolean put(@ParametricNullness K key, @ParametricNullness V value) {
     return get(key).add(value);
   }
 
   @CanIgnoreReturnValue
   @Override
-  public boolean putAll(@NullableDecl K key, Iterable<? extends V> values) {
+  public boolean putAll(@ParametricNullness K key, Iterable<? extends V> values) {
     checkNotNull(values);
     // make sure we only call values.iterator() once
     // and we only call get(key) if values is nonempty
@@ -99,14 +102,14 @@ public boolean putAll(Multimap<? extends K, ? extends V> multimap) {
 
   @CanIgnoreReturnValue
   @Override
-  public Collection<V> replaceValues(@NullableDecl K key, Iterable<? extends V> values) {
+  public Collection<V> replaceValues(@ParametricNullness K key, Iterable<? extends V> values) {
     checkNotNull(values);
     Collection<V> result = removeAll(key);
     putAll(key, values);
     return result;
   }
 
-  @LazyInit @NullableDecl private transient Collection<Entry<K, V>> entries;
+  @LazyInit @CheckForNull private transient Collection<Entry<K, V>> entries;
 
   @Override
   public Collection<Entry<K, V>> entries() {
@@ -137,14 +140,14 @@ public int hashCode() {
     }
 
     @Override
-    public boolean equals(@NullableDecl Object obj) {
+    public boolean equals(@CheckForNull Object obj) {
       return Sets.equalsImpl(this, obj);
     }
   }
 
   abstract Iterator<Entry<K, V>> entryIterator();
 
-  @LazyInit @NullableDecl private transient Set<K> keySet;
+  @LazyInit @CheckForNull private transient Set<K> keySet;
 
   @Override
   public Set<K> keySet() {
@@ -154,7 +157,7 @@ public Set<K> keySet() {
 
   abstract Set<K> createKeySet();
 
-  @LazyInit @NullableDecl private transient Multiset<K> keys;
+  @LazyInit @CheckForNull private transient Multiset<K> keys;
 
   @Override
   public Multiset<K> keys() {
@@ -164,7 +167,7 @@ public Multiset<K> keys() {
 
   abstract Multiset<K> createKeys();
 
-  @LazyInit @NullableDecl private transient Collection<V> values;
+  @LazyInit @CheckForNull private transient Collection<V> values;
 
   @Override
   public Collection<V> values() {
@@ -187,7 +190,7 @@ public int size() {
     }
 
     @Override
-    public boolean contains(@NullableDecl Object o) {
+    public boolean contains(@CheckForNull Object o) {
       return AbstractMultimap.this.containsValue(o);
     }
 
@@ -201,7 +204,7 @@ Iterator<V> valueIterator() {
     return Maps.valueIterator(entries().iterator());
   }
 
-  @LazyInit @NullableDecl private transient Map<K, Collection<V>> asMap;
+  @LazyInit @CheckForNull private transient Map<K, Collection<V>> asMap;
 
   @Override
   public Map<K, Collection<V>> asMap() {
@@ -214,7 +217,7 @@ public Map<K, Collection<V>> asMap() {
   // Comparison and hashing
 
   @Override
-  public boolean equals(@NullableDecl Object object) {
+  public boolean equals(@CheckForNull Object object) {
     return Multimaps.equalsImpl(this, object);
   }
 
diff --git a/android/guava/src/com/google/common/collect/AbstractMultiset.java b/android/guava/src/com/google/common/collect/AbstractMultiset.java
index c0a7f5e384ce..8203e44598a0 100644
--- a/android/guava/src/com/google/common/collect/AbstractMultiset.java
+++ b/android/guava/src/com/google/common/collect/AbstractMultiset.java
@@ -26,7 +26,8 @@
 import java.util.Collection;
 import java.util.Iterator;
 import java.util.Set;
-import org.checkerframework.checker.nullness.compatqual.NullableDecl;
+import javax.annotation.CheckForNull;
+import org.checkerframework.checker.nullness.qual.Nullable;
 
 /**
  * This class provides a skeletal implementation of the {@link Multiset} interface. A new multiset
@@ -42,7 +43,9 @@
  * @author Louis Wasserman
  */
 @GwtCompatible
-abstract class AbstractMultiset<E> extends AbstractCollection<E> implements Multiset<E> {
+@ElementTypesAreNonnullByDefault
+abstract class AbstractMultiset<E extends @Nullable Object> extends AbstractCollection<E>
+    implements Multiset<E> {
   // Query Operations
 
   @Override
@@ -51,45 +54,45 @@ public boolean isEmpty() {
   }
 
   @Override
-  public boolean contains(@NullableDecl Object element) {
+  public boolean contains(@CheckForNull Object element) {
     return count(element) > 0;
   }
 
   // Modification Operations
   @CanIgnoreReturnValue
   @Override
-  public final boolean add(@NullableDecl E element) {
+  public final boolean add(@ParametricNullness E element) {
     add(element, 1);
     return true;
   }
 
   @CanIgnoreReturnValue
   @Override
-  public int add(@NullableDecl E element, int occurrences) {
+  public int add(@ParametricNullness E element, int occurrences) {
     throw new UnsupportedOperationException();
   }
 
   @CanIgnoreReturnValue
   @Override
-  public final boolean remove(@NullableDecl Object element) {
+  public final boolean remove(@CheckForNull Object element) {
     return remove(element, 1) > 0;
   }
 
   @CanIgnoreReturnValue
   @Override
-  public int remove(@NullableDecl Object element, int occurrences) {
+  public int remove(@CheckForNull Object element, int occurrences) {
     throw new UnsupportedOperationException();
   }
 
   @CanIgnoreReturnValue
   @Override
-  public int setCount(@NullableDecl E element, int count) {
+  public int setCount(@ParametricNullness E element, int count) {
     return setCountImpl(this, element, count);
   }
 
   @CanIgnoreReturnValue
   @Override
-  public boolean setCount(@NullableDecl E element, int oldCount, int newCount) {
+  public boolean setCount(@ParametricNullness E element, int oldCount, int newCount) {
     return setCountImpl(this, element, oldCount, newCount);
   }
 
@@ -124,7 +127,7 @@ public final boolean retainAll(Collection<?> elementsToRetain) {
 
   // Views
 
-  @LazyInit @NullableDecl private transient Set<E> elementSet;
+  @LazyInit @CheckForNull private transient Set<E> elementSet;
 
   @Override
   public Set<E> elementSet() {
@@ -158,7 +161,7 @@ public Iterator<E> iterator() {
 
   abstract Iterator<E> elementIterator();
 
-  @LazyInit @NullableDecl private transient Set<Entry<E>> entrySet;
+  @LazyInit @CheckForNull private transient Set<Entry<E>> entrySet;
 
   @Override
   public Set<Entry<E>> entrySet() {
@@ -204,7 +207,7 @@ Set<Entry<E>> createEntrySet() {
    * and if, for each element, the two multisets have the same count.
    */
   @Override
-  public final boolean equals(@NullableDecl Object object) {
+  public final boolean equals(@CheckForNull Object object) {
     return Multisets.equalsImpl(this, object);
   }
 
diff --git a/android/guava/src/com/google/common/collect/AbstractNavigableMap.java b/android/guava/src/com/google/common/collect/AbstractNavigableMap.java
index e5259e829e4e..47048d06ac49 100644
--- a/android/guava/src/com/google/common/collect/AbstractNavigableMap.java
+++ b/android/guava/src/com/google/common/collect/AbstractNavigableMap.java
@@ -24,7 +24,8 @@
 import java.util.NoSuchElementException;
 import java.util.Set;
 import java.util.SortedMap;
-import org.checkerframework.checker.nullness.compatqual.NullableDecl;
+import javax.annotation.CheckForNull;
+import org.checkerframework.checker.nullness.qual.Nullable;
 
 /**
  * Skeletal implementation of {@link NavigableMap}.
@@ -32,38 +33,40 @@
  * @author Louis Wasserman
  */
 @GwtIncompatible
-abstract class AbstractNavigableMap<K, V> extends IteratorBasedAbstractMap<K, V>
-    implements NavigableMap<K, V> {
+@ElementTypesAreNonnullByDefault
+abstract class AbstractNavigableMap<K extends @Nullable Object, V extends @Nullable Object>
+    extends IteratorBasedAbstractMap<K, V> implements NavigableMap<K, V> {
 
   @Override
-  @NullableDecl
-  public abstract V get(@NullableDecl Object key);
+  @CheckForNull
+  public abstract V get(@CheckForNull Object key);
 
   @Override
-  @NullableDecl
+  @CheckForNull
   public Entry<K, V> firstEntry() {
     return Iterators.getNext(entryIterator(), null);
   }
 
   @Override
-  @NullableDecl
+  @CheckForNull
   public Entry<K, V> lastEntry() {
     return Iterators.getNext(descendingEntryIterator(), null);
   }
 
   @Override
-  @NullableDecl
+  @CheckForNull
   public Entry<K, V> pollFirstEntry() {
     return Iterators.pollNext(entryIterator());
   }
 
   @Override
-  @NullableDecl
+  @CheckForNull
   public Entry<K, V> pollLastEntry() {
     return Iterators.pollNext(descendingEntryIterator());
   }
 
   @Override
+  @ParametricNullness
   public K firstKey() {
     Entry<K, V> entry = firstEntry();
     if (entry == null) {
@@ -74,6 +77,7 @@ public K firstKey() {
   }
 
   @Override
+  @ParametricNullness
   public K lastKey() {
     Entry<K, V> entry = lastEntry();
     if (entry == null) {
@@ -84,63 +88,67 @@ public K lastKey() {
   }
 
   @Override
-  @NullableDecl
-  public Entry<K, V> lowerEntry(K key) {
+  @CheckForNull
+  public Entry<K, V> lowerEntry(@ParametricNullness K key) {
     return headMap(key, false).lastEntry();
   }
 
   @Override
-  @NullableDecl
-  public Entry<K, V> floorEntry(K key) {
+  @CheckForNull
+  public Entry<K, V> floorEntry(@ParametricNullness K key) {
     return headMap(key, true).lastEntry();
   }
 
   @Override
-  @NullableDecl
-  public Entry<K, V> ceilingEntry(K key) {
+  @CheckForNull
+  public Entry<K, V> ceilingEntry(@ParametricNullness K key) {
     return tailMap(key, true).firstEntry();
   }
 
   @Override
-  @NullableDecl
-  public Entry<K, V> higherEntry(K key) {
+  @CheckForNull
+  public Entry<K, V> higherEntry(@ParametricNullness K key) {
     return tailMap(key, false).firstEntry();
   }
 
   @Override
-  public K lowerKey(K key) {
+  @CheckForNull
+  public K lowerKey(@ParametricNullness K key) {
     return Maps.keyOrNull(lowerEntry(key));
   }
 
   @Override
-  public K floorKey(K key) {
+  @CheckForNull
+  public K floorKey(@ParametricNullness K key) {
     return Maps.keyOrNull(floorEntry(key));
   }
 
   @Override
-  public K ceilingKey(K key) {
+  @CheckForNull
+  public K ceilingKey(@ParametricNullness K key) {
     return Maps.keyOrNull(ceilingEntry(key));
   }
 
   @Override
-  public K higherKey(K key) {
+  @CheckForNull
+  public K higherKey(@ParametricNullness K key) {
     return Maps.keyOrNull(higherEntry(key));
   }
 
   abstract Iterator<Entry<K, V>> descendingEntryIterator();
 
   @Override
-  public SortedMap<K, V> subMap(K fromKey, K toKey) {
+  public SortedMap<K, V> subMap(@ParametricNullness K fromKey, @ParametricNullness K toKey) {
     return subMap(fromKey, true, toKey, false);
   }
 
   @Override
-  public SortedMap<K, V> headMap(K toKey) {
+  public SortedMap<K, V> headMap(@ParametricNullness K toKey) {
     return headMap(toKey, false);
   }
 
   @Override
-  public SortedMap<K, V> tailMap(K fromKey) {
+  public SortedMap<K, V> tailMap(@ParametricNullness K fromKey) {
     return tailMap(fromKey, true);
   }
 
diff --git a/android/guava/src/com/google/common/collect/AbstractRangeSet.java b/android/guava/src/com/google/common/collect/AbstractRangeSet.java
index 42ae89380186..032be3d5b03e 100644
--- a/android/guava/src/com/google/common/collect/AbstractRangeSet.java
+++ b/android/guava/src/com/google/common/collect/AbstractRangeSet.java
@@ -15,7 +15,7 @@
 package com.google.common.collect;
 
 import com.google.common.annotations.GwtIncompatible;
-import org.checkerframework.checker.nullness.compatqual.NullableDecl;
+import javax.annotation.CheckForNull;
 
 /**
  * A skeletal implementation of {@code RangeSet}.
@@ -23,6 +23,7 @@
  * @author Louis Wasserman
  */
 @GwtIncompatible
+@ElementTypesAreNonnullByDefault
 abstract class AbstractRangeSet<C extends Comparable> implements RangeSet<C> {
   AbstractRangeSet() {}
 
@@ -32,6 +33,7 @@ public boolean contains(C value) {
   }
 
   @Override
+  @CheckForNull
   public abstract Range<C> rangeContaining(C value);
 
   @Override
@@ -102,7 +104,7 @@ public boolean intersects(Range<C> otherRange) {
   public abstract boolean encloses(Range<C> otherRange);
 
   @Override
-  public boolean equals(@NullableDecl Object obj) {
+  public boolean equals(@CheckForNull Object obj) {
     if (obj == this) {
       return true;
     } else if (obj instanceof RangeSet) {
diff --git a/android/guava/src/com/google/common/collect/AbstractSequentialIterator.java b/android/guava/src/com/google/common/collect/AbstractSequentialIterator.java
index bda06924fcaa..172fe356cb78 100644
--- a/android/guava/src/com/google/common/collect/AbstractSequentialIterator.java
+++ b/android/guava/src/com/google/common/collect/AbstractSequentialIterator.java
@@ -18,7 +18,7 @@
 
 import com.google.common.annotations.GwtCompatible;
 import java.util.NoSuchElementException;
-import org.checkerframework.checker.nullness.compatqual.NullableDecl;
+import javax.annotation.CheckForNull;
 
 /**
  * This class provides a skeletal implementation of the {@code Iterator} interface for sequences
@@ -40,14 +40,15 @@
  * @since 12.0 (in Guava as {@code AbstractLinkedIterator} since 8.0)
  */
 @GwtCompatible
+@ElementTypesAreNonnullByDefault
 public abstract class AbstractSequentialIterator<T> extends UnmodifiableIterator<T> {
-  @NullableDecl private T nextOrNull;
+  @CheckForNull private T nextOrNull;
 
   /**
    * Creates a new iterator with the given first element, or, if {@code firstOrNull} is null,
    * creates a new empty iterator.
    */
-  protected AbstractSequentialIterator(@NullableDecl T firstOrNull) {
+  protected AbstractSequentialIterator(@CheckForNull T firstOrNull) {
     this.nextOrNull = firstOrNull;
   }
 
@@ -56,7 +57,7 @@ protected AbstractSequentialIterator(@NullableDecl T firstOrNull) {
    * remain. This method is invoked during each call to {@link #next()} in order to compute the
    * result of a <i>future</i> call to {@code next()}.
    */
-  @NullableDecl
+  @CheckForNull
   protected abstract T computeNext(T previous);
 
   @Override
@@ -66,13 +67,11 @@ public final boolean hasNext() {
 
   @Override
   public final T next() {
-    if (!hasNext()) {
+    if (nextOrNull == null) {
       throw new NoSuchElementException();
     }
-    try {
-      return nextOrNull;
-    } finally {
-      nextOrNull = computeNext(nextOrNull);
-    }
+    T oldNext = nextOrNull;
+    nextOrNull = computeNext(oldNext);
+    return oldNext;
   }
 }
diff --git a/android/guava/src/com/google/common/collect/AbstractSetMultimap.java b/android/guava/src/com/google/common/collect/AbstractSetMultimap.java
index 2779d1cbde5d..90aa9dcb2f79 100644
--- a/android/guava/src/com/google/common/collect/AbstractSetMultimap.java
+++ b/android/guava/src/com/google/common/collect/AbstractSetMultimap.java
@@ -23,7 +23,8 @@
 import java.util.Map;
 import java.util.Map.Entry;
 import java.util.Set;
-import org.checkerframework.checker.nullness.compatqual.NullableDecl;
+import javax.annotation.CheckForNull;
+import org.checkerframework.checker.nullness.qual.Nullable;
 
 /**
  * Basic implementation of the {@link SetMultimap} interface. It's a wrapper around {@link
@@ -33,8 +34,9 @@
  * @author Jared Levy
  */
 @GwtCompatible
-abstract class AbstractSetMultimap<K, V> extends AbstractMapBasedMultimap<K, V>
-    implements SetMultimap<K, V> {
+@ElementTypesAreNonnullByDefault
+abstract class AbstractSetMultimap<K extends @Nullable Object, V extends @Nullable Object>
+    extends AbstractMapBasedMultimap<K, V> implements SetMultimap<K, V> {
   /**
    * Creates a new multimap that uses the provided map.
    *
@@ -53,12 +55,13 @@ Set<V> createUnmodifiableEmptyCollection() {
   }
 
   @Override
-  <E> Collection<E> unmodifiableCollectionSubclass(Collection<E> collection) {
+  <E extends @Nullable Object> Collection<E> unmodifiableCollectionSubclass(
+      Collection<E> collection) {
     return Collections.unmodifiableSet((Set<E>) collection);
   }
 
   @Override
-  Collection<V> wrapCollection(K key, Collection<V> collection) {
+  Collection<V> wrapCollection(@ParametricNullness K key, Collection<V> collection) {
     return new WrappedSet(key, (Set<V>) collection);
   }
 
@@ -71,7 +74,7 @@ Collection<V> wrapCollection(K key, Collection<V> collection) {
    * {@link Set}, instead of the {@link Collection} specified in the {@link Multimap} interface.
    */
   @Override
-  public Set<V> get(@NullableDecl K key) {
+  public Set<V> get(@ParametricNullness K key) {
     return (Set<V>) super.get(key);
   }
 
@@ -94,7 +97,7 @@ public Set<Entry<K, V>> entries() {
    */
   @CanIgnoreReturnValue
   @Override
-  public Set<V> removeAll(@NullableDecl Object key) {
+  public Set<V> removeAll(@CheckForNull Object key) {
     return (Set<V>) super.removeAll(key);
   }
 
@@ -108,7 +111,7 @@ public Set<V> removeAll(@NullableDecl Object key) {
    */
   @CanIgnoreReturnValue
   @Override
-  public Set<V> replaceValues(@NullableDecl K key, Iterable<? extends V> values) {
+  public Set<V> replaceValues(@ParametricNullness K key, Iterable<? extends V> values) {
     return (Set<V>) super.replaceValues(key, values);
   }
 
@@ -133,7 +136,7 @@ public Map<K, Collection<V>> asMap() {
    */
   @CanIgnoreReturnValue
   @Override
-  public boolean put(@NullableDecl K key, @NullableDecl V value) {
+  public boolean put(@ParametricNullness K key, @ParametricNullness V value) {
     return super.put(key, value);
   }
 
@@ -144,7 +147,7 @@ public boolean put(@NullableDecl K key, @NullableDecl V value) {
    * Equality does not depend on the ordering of keys or values.
    */
   @Override
-  public boolean equals(@NullableDecl Object object) {
+  public boolean equals(@CheckForNull Object object) {
     return super.equals(object);
   }
 
diff --git a/android/guava/src/com/google/common/collect/AbstractSortedKeySortedSetMultimap.java b/android/guava/src/com/google/common/collect/AbstractSortedKeySortedSetMultimap.java
index 0ee6edb1e090..676936f0578e 100644
--- a/android/guava/src/com/google/common/collect/AbstractSortedKeySortedSetMultimap.java
+++ b/android/guava/src/com/google/common/collect/AbstractSortedKeySortedSetMultimap.java
@@ -21,6 +21,7 @@
 import java.util.Set;
 import java.util.SortedMap;
 import java.util.SortedSet;
+import org.checkerframework.checker.nullness.qual.Nullable;
 
 /**
  * Basic implementation of a {@link SortedSetMultimap} with a sorted key set.
@@ -31,7 +32,10 @@
  * @author Louis Wasserman
  */
 @GwtCompatible
-abstract class AbstractSortedKeySortedSetMultimap<K, V> extends AbstractSortedSetMultimap<K, V> {
+@ElementTypesAreNonnullByDefault
+abstract class AbstractSortedKeySortedSetMultimap<
+        K extends @Nullable Object, V extends @Nullable Object>
+    extends AbstractSortedSetMultimap<K, V> {
 
   AbstractSortedKeySortedSetMultimap(SortedMap<K, Collection<V>> map) {
     super(map);
diff --git a/android/guava/src/com/google/common/collect/AbstractSortedMultiset.java b/android/guava/src/com/google/common/collect/AbstractSortedMultiset.java
index 091bb8cbce47..621e8f98a5e2 100644
--- a/android/guava/src/com/google/common/collect/AbstractSortedMultiset.java
+++ b/android/guava/src/com/google/common/collect/AbstractSortedMultiset.java
@@ -21,7 +21,8 @@
 import java.util.Comparator;
 import java.util.Iterator;
 import java.util.NavigableSet;
-import org.checkerframework.checker.nullness.compatqual.NullableDecl;
+import javax.annotation.CheckForNull;
+import org.checkerframework.checker.nullness.qual.Nullable;
 
 /**
  * This class provides a skeletal implementation of the {@link SortedMultiset} interface.
@@ -33,7 +34,9 @@
  * @author Louis Wasserman
  */
 @GwtCompatible(emulated = true)
-abstract class AbstractSortedMultiset<E> extends AbstractMultiset<E> implements SortedMultiset<E> {
+@ElementTypesAreNonnullByDefault
+abstract class AbstractSortedMultiset<E extends @Nullable Object> extends AbstractMultiset<E>
+    implements SortedMultiset<E> {
   @GwtTransient final Comparator<? super E> comparator;
 
   // needed for serialization
@@ -53,7 +56,7 @@ public NavigableSet<E> elementSet() {
 
   @Override
   NavigableSet<E> createElementSet() {
-    return new SortedMultisets.NavigableElementSet<E>(this);
+    return new SortedMultisets.NavigableElementSet<>(this);
   }
 
   @Override
@@ -62,18 +65,21 @@ public Comparator<? super E> comparator() {
   }
 
   @Override
+  @CheckForNull
   public Entry<E> firstEntry() {
     Iterator<Entry<E>> entryIterator = entryIterator();
     return entryIterator.hasNext() ? entryIterator.next() : null;
   }
 
   @Override
+  @CheckForNull
   public Entry<E> lastEntry() {
     Iterator<Entry<E>> entryIterator = descendingEntryIterator();
     return entryIterator.hasNext() ? entryIterator.next() : null;
   }
 
   @Override
+  @CheckForNull
   public Entry<E> pollFirstEntry() {
     Iterator<Entry<E>> entryIterator = entryIterator();
     if (entryIterator.hasNext()) {
@@ -86,6 +92,7 @@ public Entry<E> pollFirstEntry() {
   }
 
   @Override
+  @CheckForNull
   public Entry<E> pollLastEntry() {
     Iterator<Entry<E>> entryIterator = descendingEntryIterator();
     if (entryIterator.hasNext()) {
@@ -99,9 +106,9 @@ public Entry<E> pollLastEntry() {
 
   @Override
   public SortedMultiset<E> subMultiset(
-      @NullableDecl E fromElement,
+      @ParametricNullness E fromElement,
       BoundType fromBoundType,
-      @NullableDecl E toElement,
+      @ParametricNullness E toElement,
       BoundType toBoundType) {
     // These are checked elsewhere, but NullPointerTester wants them checked eagerly.
     checkNotNull(fromBoundType);
@@ -115,7 +122,7 @@ Iterator<E> descendingIterator() {
     return Multisets.iteratorImpl(descendingMultiset());
   }
 
-  @NullableDecl private transient SortedMultiset<E> descendingMultiset;
+  @CheckForNull private transient SortedMultiset<E> descendingMultiset;
 
   @Override
   public SortedMultiset<E> descendingMultiset() {
diff --git a/android/guava/src/com/google/common/collect/AbstractSortedSetMultimap.java b/android/guava/src/com/google/common/collect/AbstractSortedSetMultimap.java
index 6254a6e62980..32316133a051 100644
--- a/android/guava/src/com/google/common/collect/AbstractSortedSetMultimap.java
+++ b/android/guava/src/com/google/common/collect/AbstractSortedSetMultimap.java
@@ -23,7 +23,8 @@
 import java.util.Map;
 import java.util.NavigableSet;
 import java.util.SortedSet;
-import org.checkerframework.checker.nullness.compatqual.NullableDecl;
+import javax.annotation.CheckForNull;
+import org.checkerframework.checker.nullness.qual.Nullable;
 
 /**
  * Basic implementation of the {@link SortedSetMultimap} interface. It's a wrapper around {@link
@@ -33,8 +34,9 @@
  * @author Jared Levy
  */
 @GwtCompatible
-abstract class AbstractSortedSetMultimap<K, V> extends AbstractSetMultimap<K, V>
-    implements SortedSetMultimap<K, V> {
+@ElementTypesAreNonnullByDefault
+abstract class AbstractSortedSetMultimap<K extends @Nullable Object, V extends @Nullable Object>
+    extends AbstractSetMultimap<K, V> implements SortedSetMultimap<K, V> {
   /**
    * Creates a new multimap that uses the provided map.
    *
@@ -53,7 +55,8 @@ SortedSet<V> createUnmodifiableEmptyCollection() {
   }
 
   @Override
-  <E> SortedSet<E> unmodifiableCollectionSubclass(Collection<E> collection) {
+  <E extends @Nullable Object> SortedSet<E> unmodifiableCollectionSubclass(
+      Collection<E> collection) {
     if (collection instanceof NavigableSet) {
       return Sets.unmodifiableNavigableSet((NavigableSet<E>) collection);
     } else {
@@ -62,7 +65,7 @@ <E> SortedSet<E> unmodifiableCollectionSubclass(Collection<E> collection) {
   }
 
   @Override
-  Collection<V> wrapCollection(K key, Collection<V> collection) {
+  Collection<V> wrapCollection(@ParametricNullness K key, Collection<V> collection) {
     if (collection instanceof NavigableSet) {
       return new WrappedNavigableSet(key, (NavigableSet<V>) collection, null);
     } else {
@@ -83,7 +86,7 @@ Collection<V> wrapCollection(K key, Collection<V> collection) {
    * Multimap} interface.
    */
   @Override
-  public SortedSet<V> get(@NullableDecl K key) {
+  public SortedSet<V> get(@ParametricNullness K key) {
     return (SortedSet<V>) super.get(key);
   }
 
@@ -96,7 +99,7 @@ public SortedSet<V> get(@NullableDecl K key) {
    */
   @CanIgnoreReturnValue
   @Override
-  public SortedSet<V> removeAll(@NullableDecl Object key) {
+  public SortedSet<V> removeAll(@CheckForNull Object key) {
     return (SortedSet<V>) super.removeAll(key);
   }
 
@@ -112,7 +115,7 @@ public SortedSet<V> removeAll(@NullableDecl Object key) {
    */
   @CanIgnoreReturnValue
   @Override
-  public SortedSet<V> replaceValues(@NullableDecl K key, Iterable<? extends V> values) {
+  public SortedSet<V> replaceValues(@ParametricNullness K key, Iterable<? extends V> values) {
     return (SortedSet<V>) super.replaceValues(key, values);
   }
 
diff --git a/android/guava/src/com/google/common/collect/AbstractTable.java b/android/guava/src/com/google/common/collect/AbstractTable.java
index 7cb34a61bb9a..fe1d4e77fedf 100644
--- a/android/guava/src/com/google/common/collect/AbstractTable.java
+++ b/android/guava/src/com/google/common/collect/AbstractTable.java
@@ -24,7 +24,8 @@
 import java.util.Iterator;
 import java.util.Map;
 import java.util.Set;
-import org.checkerframework.checker.nullness.compatqual.NullableDecl;
+import javax.annotation.CheckForNull;
+import org.checkerframework.checker.nullness.qual.Nullable;
 
 /**
  * Skeletal, implementation-agnostic implementation of the {@link Table} interface.
@@ -32,15 +33,18 @@
  * @author Louis Wasserman
  */
 @GwtCompatible
-abstract class AbstractTable<R, C, V> implements Table<R, C, V> {
+@ElementTypesAreNonnullByDefault
+abstract class AbstractTable<
+        R extends @Nullable Object, C extends @Nullable Object, V extends @Nullable Object>
+    implements Table<R, C, V> {
 
   @Override
-  public boolean containsRow(@NullableDecl Object rowKey) {
+  public boolean containsRow(@CheckForNull Object rowKey) {
     return Maps.safeContainsKey(rowMap(), rowKey);
   }
 
   @Override
-  public boolean containsColumn(@NullableDecl Object columnKey) {
+  public boolean containsColumn(@CheckForNull Object columnKey) {
     return Maps.safeContainsKey(columnMap(), columnKey);
   }
 
@@ -55,7 +59,7 @@ public Set<C> columnKeySet() {
   }
 
   @Override
-  public boolean containsValue(@NullableDecl Object value) {
+  public boolean containsValue(@CheckForNull Object value) {
     for (Map<C, V> row : rowMap().values()) {
       if (row.containsValue(value)) {
         return true;
@@ -65,13 +69,14 @@ public boolean containsValue(@NullableDecl Object value) {
   }
 
   @Override
-  public boolean contains(@NullableDecl Object rowKey, @NullableDecl Object columnKey) {
+  public boolean contains(@CheckForNull Object rowKey, @CheckForNull Object columnKey) {
     Map<C, V> row = Maps.safeGet(rowMap(), rowKey);
     return row != null && Maps.safeContainsKey(row, columnKey);
   }
 
   @Override
-  public V get(@NullableDecl Object rowKey, @NullableDecl Object columnKey) {
+  @CheckForNull
+  public V get(@CheckForNull Object rowKey, @CheckForNull Object columnKey) {
     Map<C, V> row = Maps.safeGet(rowMap(), rowKey);
     return (row == null) ? null : Maps.safeGet(row, columnKey);
   }
@@ -88,14 +93,17 @@ public void clear() {
 
   @CanIgnoreReturnValue
   @Override
-  public V remove(@NullableDecl Object rowKey, @NullableDecl Object columnKey) {
+  @CheckForNull
+  public V remove(@CheckForNull Object rowKey, @CheckForNull Object columnKey) {
     Map<C, V> row = Maps.safeGet(rowMap(), rowKey);
     return (row == null) ? null : Maps.safeRemove(row, columnKey);
   }
 
   @CanIgnoreReturnValue
   @Override
-  public V put(R rowKey, C columnKey, V value) {
+  @CheckForNull
+  public V put(
+      @ParametricNullness R rowKey, @ParametricNullness C columnKey, @ParametricNullness V value) {
     return row(rowKey).put(columnKey, value);
   }
 
@@ -106,7 +114,7 @@ public void putAll(Table<? extends R, ? extends C, ? extends V> table) {
     }
   }
 
-  @LazyInit @NullableDecl private transient Set<Cell<R, C, V>> cellSet;
+  @LazyInit @CheckForNull private transient Set<Cell<R, C, V>> cellSet;
 
   @Override
   public Set<Cell<R, C, V>> cellSet() {
@@ -123,7 +131,7 @@ Set<Cell<R, C, V>> createCellSet() {
   @WeakOuter
   class CellSet extends AbstractSet<Cell<R, C, V>> {
     @Override
-    public boolean contains(Object o) {
+    public boolean contains(@CheckForNull Object o) {
       if (o instanceof Cell) {
         Cell<?, ?, ?> cell = (Cell<?, ?, ?>) o;
         Map<C, V> row = Maps.safeGet(rowMap(), cell.getRowKey());
@@ -135,7 +143,7 @@ public boolean contains(Object o) {
     }
 
     @Override
-    public boolean remove(@NullableDecl Object o) {
+    public boolean remove(@CheckForNull Object o) {
       if (o instanceof Cell) {
         Cell<?, ?, ?> cell = (Cell<?, ?, ?>) o;
         Map<C, V> row = Maps.safeGet(rowMap(), cell.getRowKey());
@@ -162,7 +170,7 @@ public int size() {
     }
   }
 
-  @LazyInit @NullableDecl private transient Collection<V> values;
+  @LazyInit @CheckForNull private transient Collection<V> values;
 
   @Override
   public Collection<V> values() {
@@ -177,6 +185,7 @@ Collection<V> createValues() {
   Iterator<V> valuesIterator() {
     return new TransformedIterator<Cell<R, C, V>, V>(cellSet().iterator()) {
       @Override
+      @ParametricNullness
       V transform(Cell<R, C, V> cell) {
         return cell.getValue();
       }
@@ -191,7 +200,7 @@ public Iterator<V> iterator() {
     }
 
     @Override
-    public boolean contains(Object o) {
+    public boolean contains(@CheckForNull Object o) {
       return containsValue(o);
     }
 
@@ -207,7 +216,7 @@ public int size() {
   }
 
   @Override
-  public boolean equals(@NullableDecl Object obj) {
+  public boolean equals(@CheckForNull Object obj) {
     return Tables.equalsImpl(this, obj);
   }
 
diff --git a/android/guava/src/com/google/common/collect/AllEqualOrdering.java b/android/guava/src/com/google/common/collect/AllEqualOrdering.java
index bbcd19e01f85..f6ca6faff797 100644
--- a/android/guava/src/com/google/common/collect/AllEqualOrdering.java
+++ b/android/guava/src/com/google/common/collect/AllEqualOrdering.java
@@ -19,7 +19,8 @@
 import com.google.common.annotations.GwtCompatible;
 import java.io.Serializable;
 import java.util.List;
-import org.checkerframework.checker.nullness.compatqual.NullableDecl;
+import javax.annotation.CheckForNull;
+import org.checkerframework.checker.nullness.qual.Nullable;
 
 /**
  * An ordering that treats all references as equals, even nulls.
@@ -27,27 +28,29 @@
  * @author Emily Soldal
  */
 @GwtCompatible(serializable = true)
-final class AllEqualOrdering extends Ordering<Object> implements Serializable {
+@ElementTypesAreNonnullByDefault
+final class AllEqualOrdering extends Ordering<@Nullable Object> implements Serializable {
   static final AllEqualOrdering INSTANCE = new AllEqualOrdering();
 
   @Override
-  public int compare(@NullableDecl Object left, @NullableDecl Object right) {
+  public int compare(@CheckForNull Object left, @CheckForNull Object right) {
     return 0;
   }
 
   @Override
-  public <E> List<E> sortedCopy(Iterable<E> iterable) {
+  public <E extends @Nullable Object> List<E> sortedCopy(Iterable<E> iterable) {
     return Lists.newArrayList(iterable);
   }
 
   @Override
-  public <E> ImmutableList<E> immutableSortedCopy(Iterable<E> iterable) {
+  @SuppressWarnings("nullness") // unsafe: see supertype
+  public <E extends @Nullable Object> ImmutableList<E> immutableSortedCopy(Iterable<E> iterable) {
     return ImmutableList.copyOf(iterable);
   }
 
   @SuppressWarnings("unchecked")
   @Override
-  public <S> Ordering<S> reverse() {
+  public <S extends @Nullable Object> Ordering<S> reverse() {
     return (Ordering<S>) this;
   }
 
diff --git a/android/guava/src/com/google/common/collect/ArrayListMultimap.java b/android/guava/src/com/google/common/collect/ArrayListMultimap.java
index 1faf476c6576..349f40770736 100644
--- a/android/guava/src/com/google/common/collect/ArrayListMultimap.java
+++ b/android/guava/src/com/google/common/collect/ArrayListMultimap.java
@@ -29,6 +29,7 @@
 import java.util.HashMap;
 import java.util.List;
 import java.util.Map;
+import org.checkerframework.checker.nullness.qual.Nullable;
 
 /**
  * Implementation of {@code Multimap} that uses an {@code ArrayList} to store the values for a given
@@ -52,14 +53,14 @@
  * with a call to {@link Multimaps#synchronizedListMultimap}.
  *
  * <p>See the Guava User Guide article on <a href=
- * "https://github.com/google/guava/wiki/NewCollectionTypesExplained#multimap"> {@code
- * Multimap}</a>.
+ * "https://github.com/google/guava/wiki/NewCollectionTypesExplained#multimap">{@code Multimap}</a>.
  *
  * @author Jared Levy
  * @since 2.0
  */
 @GwtCompatible(serializable = true, emulated = true)
-public final class ArrayListMultimap<K, V>
+@ElementTypesAreNonnullByDefault
+public final class ArrayListMultimap<K extends @Nullable Object, V extends @Nullable Object>
     extends ArrayListMultimapGwtSerializationDependencies<K, V> {
   // Default from ArrayList
   private static final int DEFAULT_VALUES_PER_KEY = 3;
@@ -72,7 +73,8 @@ public final class ArrayListMultimap<K, V>
    * <p>This method will soon be deprecated in favor of {@code
    * MultimapBuilder.hashKeys().arrayListValues().build()}.
    */
-  public static <K, V> ArrayListMultimap<K, V> create() {
+  public static <K extends @Nullable Object, V extends @Nullable Object>
+      ArrayListMultimap<K, V> create() {
     return new ArrayListMultimap<>();
   }
 
@@ -88,7 +90,8 @@ public static <K, V> ArrayListMultimap<K, V> create() {
    * @throws IllegalArgumentException if {@code expectedKeys} or {@code expectedValuesPerKey} is
    *     negative
    */
-  public static <K, V> ArrayListMultimap<K, V> create(int expectedKeys, int expectedValuesPerKey) {
+  public static <K extends @Nullable Object, V extends @Nullable Object>
+      ArrayListMultimap<K, V> create(int expectedKeys, int expectedValuesPerKey) {
     return new ArrayListMultimap<>(expectedKeys, expectedValuesPerKey);
   }
 
@@ -100,7 +103,8 @@ public static <K, V> ArrayListMultimap<K, V> create(int expectedKeys, int expect
    *
    * @param multimap the multimap whose contents are copied to this multimap
    */
-  public static <K, V> ArrayListMultimap<K, V> create(Multimap<? extends K, ? extends V> multimap) {
+  public static <K extends @Nullable Object, V extends @Nullable Object>
+      ArrayListMultimap<K, V> create(Multimap<? extends K, ? extends V> multimap) {
     return new ArrayListMultimap<>(multimap);
   }
 
diff --git a/android/guava/src/com/google/common/collect/ArrayTable.java b/android/guava/src/com/google/common/collect/ArrayTable.java
index 340ee72b3fc8..aa042877c87e 100644
--- a/android/guava/src/com/google/common/collect/ArrayTable.java
+++ b/android/guava/src/com/google/common/collect/ArrayTable.java
@@ -19,6 +19,7 @@
 import static com.google.common.base.Preconditions.checkArgument;
 import static com.google.common.base.Preconditions.checkElementIndex;
 import static com.google.common.base.Preconditions.checkNotNull;
+import static java.util.Collections.emptyMap;
 
 import com.google.common.annotations.Beta;
 import com.google.common.annotations.GwtCompatible;
@@ -35,11 +36,22 @@
 import java.util.Iterator;
 import java.util.Map;
 import java.util.Set;
-import org.checkerframework.checker.nullness.compatqual.NullableDecl;
+import javax.annotation.CheckForNull;
+import org.checkerframework.checker.nullness.qual.Nullable;
 
 /**
  * Fixed-size {@link Table} implementation backed by a two-dimensional array.
  *
+ * <p><b>Warning:</b> {@code ArrayTable} is rarely the {@link Table} implementation you want. First,
+ * it requires that the complete universe of rows and columns be specified at construction time.
+ * Second, it is always backed by an array large enough to hold a value for every possible
+ * combination of row and column keys. (This is rarely optimal unless the table is extremely dense.)
+ * Finally, every possible combination of row and column keys is always considered to have a value
+ * associated with it: It is not possible to "remove" a value, only to replace it with {@code null},
+ * which will still appear when iterating over the table's contents in a foreach loop or a call to a
+ * null-hostile method like {@link ImmutableTable#copyOf}. For alternatives, please see <a
+ * href="https://github.com/google/guava/wiki/NewCollectionTypesExplained#table">the wiki</a>.
+ *
  * <p>The allowed row and column keys must be supplied when the table is created. The table always
  * contains a mapping for every row key / column pair. The value corresponding to a given row and
  * column is null unless another value is provided.
@@ -71,14 +83,16 @@
  * thread that reads from another.
  *
  * <p>See the Guava User Guide article on <a href=
- * "https://github.com/google/guava/wiki/NewCollectionTypesExplained#table"> {@code Table}</a>.
+ * "https://github.com/google/guava/wiki/NewCollectionTypesExplained#table">{@code Table}</a>.
  *
  * @author Jared Levy
  * @since 10.0
  */
 @Beta
 @GwtCompatible(emulated = true)
-public final class ArrayTable<R, C, V> extends AbstractTable<R, C, V> implements Serializable {
+@ElementTypesAreNonnullByDefault
+public final class ArrayTable<R, C, V> extends AbstractTable<R, C, @Nullable V>
+    implements Serializable {
 
   /**
    * Creates an {@code ArrayTable} filled with {@code null}.
@@ -118,8 +132,8 @@ public static <R, C, V> ArrayTable<R, C, V> create(
    *
    * @throws NullPointerException if {@code table} has a null key
    */
-  public static <R, C, V> ArrayTable<R, C, V> create(Table<R, C, V> table) {
-    return (table instanceof ArrayTable<?, ?, ?>)
+  public static <R, C, V> ArrayTable<R, C, V> create(Table<R, C, ? extends @Nullable V> table) {
+    return (table instanceof ArrayTable)
         ? new ArrayTable<R, C, V>((ArrayTable<R, C, V>) table)
         : new ArrayTable<R, C, V>(table);
   }
@@ -130,7 +144,7 @@ public static <R, C, V> ArrayTable<R, C, V> create(Table<R, C, V> table) {
   // TODO(jlevy): Add getters returning rowKeyToIndex and columnKeyToIndex?
   private final ImmutableMap<R, Integer> rowKeyToIndex;
   private final ImmutableMap<C, Integer> columnKeyToIndex;
-  private final V[][] array;
+  private final @Nullable V[][] array;
 
   private ArrayTable(Iterable<? extends R> rowKeys, Iterable<? extends C> columnKeys) {
     this.rowList = ImmutableList.copyOf(rowKeys);
@@ -147,13 +161,14 @@ private ArrayTable(Iterable<? extends R> rowKeys, Iterable<? extends C> columnKe
     columnKeyToIndex = Maps.indexMap(columnList);
 
     @SuppressWarnings("unchecked")
-    V[][] tmpArray = (V[][]) new Object[rowList.size()][columnList.size()];
+    @Nullable
+    V[][] tmpArray = (@Nullable V[][]) new Object[rowList.size()][columnList.size()];
     array = tmpArray;
     // Necessary because in GWT the arrays are initialized with "undefined" instead of null.
     eraseAll();
   }
 
-  private ArrayTable(Table<R, C, V> table) {
+  private ArrayTable(Table<R, C, ? extends @Nullable V> table) {
     this(table.rowKeySet(), table.columnKeySet());
     putAll(table);
   }
@@ -164,14 +179,16 @@ private ArrayTable(ArrayTable<R, C, V> table) {
     rowKeyToIndex = table.rowKeyToIndex;
     columnKeyToIndex = table.columnKeyToIndex;
     @SuppressWarnings("unchecked")
-    V[][] copy = (V[][]) new Object[rowList.size()][columnList.size()];
+    @Nullable
+    V[][] copy = (@Nullable V[][]) new Object[rowList.size()][columnList.size()];
     array = copy;
     for (int i = 0; i < rowList.size(); i++) {
       System.arraycopy(table.array[i], 0, copy[i], 0, table.array[i].length);
     }
   }
 
-  private abstract static class ArrayMap<K, V> extends IteratorBasedAbstractMap<K, V> {
+  private abstract static class ArrayMap<K, V extends @Nullable Object>
+      extends IteratorBasedAbstractMap<K, V> {
     private final ImmutableMap<K, Integer> keyIndex;
 
     private ArrayMap(ImmutableMap<K, Integer> keyIndex) {
@@ -189,11 +206,11 @@ K getKey(int index) {
 
     abstract String getKeyRole();
 
-    @NullableDecl
+    @ParametricNullness
     abstract V getValue(int index);
 
-    @NullableDecl
-    abstract V setValue(int index, V newValue);
+    @ParametricNullness
+    abstract V setValue(int index, @ParametricNullness V newValue);
 
     @Override
     public int size() {
@@ -214,12 +231,14 @@ public K getKey() {
         }
 
         @Override
+        @ParametricNullness
         public V getValue() {
           return ArrayMap.this.getValue(index);
         }
 
         @Override
-        public V setValue(V value) {
+        @ParametricNullness
+        public V setValue(@ParametricNullness V value) {
           return ArrayMap.this.setValue(index, value);
         }
       };
@@ -238,12 +257,13 @@ protected Entry<K, V> get(final int index) {
     // TODO(lowasser): consider an optimized values() implementation
 
     @Override
-    public boolean containsKey(@NullableDecl Object key) {
+    public boolean containsKey(@CheckForNull Object key) {
       return keyIndex.containsKey(key);
     }
 
+    @CheckForNull
     @Override
-    public V get(@NullableDecl Object key) {
+    public V get(@CheckForNull Object key) {
       Integer index = keyIndex.get(key);
       if (index == null) {
         return null;
@@ -253,7 +273,8 @@ public V get(@NullableDecl Object key) {
     }
 
     @Override
-    public V put(K key, V value) {
+    @CheckForNull
+    public V put(K key, @ParametricNullness V value) {
       Integer index = keyIndex.get(key);
       if (index == null) {
         throw new IllegalArgumentException(
@@ -263,7 +284,8 @@ public V put(K key, V value) {
     }
 
     @Override
-    public V remove(Object key) {
+    @CheckForNull
+    public V remove(@CheckForNull Object key) {
       throw new UnsupportedOperationException();
     }
 
@@ -301,6 +323,7 @@ public ImmutableList<C> columnKeyList() {
    *     or equal to the number of allowed row keys, or {@code columnIndex} is greater than or equal
    *     to the number of allowed column keys
    */
+  @CheckForNull
   public V at(int rowIndex, int columnIndex) {
     // In GWT array access never throws IndexOutOfBoundsException.
     checkElementIndex(rowIndex, rowList.size());
@@ -322,7 +345,8 @@ public V at(int rowIndex, int columnIndex) {
    *     to the number of allowed column keys
    */
   @CanIgnoreReturnValue
-  public V set(int rowIndex, int columnIndex, @NullableDecl V value) {
+  @CheckForNull
+  public V set(int rowIndex, int columnIndex, @CheckForNull V value) {
     // In GWT array access never throws IndexOutOfBoundsException.
     checkElementIndex(rowIndex, rowList.size());
     checkElementIndex(columnIndex, columnList.size());
@@ -341,9 +365,10 @@ public V set(int rowIndex, int columnIndex, @NullableDecl V value) {
    * @param valueClass class of values stored in the returned array
    */
   @GwtIncompatible // reflection
-  public V[][] toArray(Class<V> valueClass) {
+  public @Nullable V[][] toArray(Class<V> valueClass) {
     @SuppressWarnings("unchecked") // TODO: safe?
-    V[][] copy = (V[][]) Array.newInstance(valueClass, rowList.size(), columnList.size());
+    @Nullable
+    V[][] copy = (@Nullable V[][]) Array.newInstance(valueClass, rowList.size(), columnList.size());
     for (int i = 0; i < rowList.size(); i++) {
       System.arraycopy(array[i], 0, copy[i], 0, array[i].length);
     }
@@ -365,7 +390,7 @@ public void clear() {
 
   /** Associates the value {@code null} with every pair of allowed row and column keys. */
   public void eraseAll() {
-    for (V[] row : array) {
+    for (@Nullable V[] row : array) {
       Arrays.fill(row, null);
     }
   }
@@ -375,7 +400,7 @@ public void eraseAll() {
    * constructed.
    */
   @Override
-  public boolean contains(@NullableDecl Object rowKey, @NullableDecl Object columnKey) {
+  public boolean contains(@CheckForNull Object rowKey, @CheckForNull Object columnKey) {
     return containsRow(rowKey) && containsColumn(columnKey);
   }
 
@@ -384,7 +409,7 @@ public boolean contains(@NullableDecl Object rowKey, @NullableDecl Object column
    * table was constructed.
    */
   @Override
-  public boolean containsColumn(@NullableDecl Object columnKey) {
+  public boolean containsColumn(@CheckForNull Object columnKey) {
     return columnKeyToIndex.containsKey(columnKey);
   }
 
@@ -393,13 +418,13 @@ public boolean containsColumn(@NullableDecl Object columnKey) {
    * constructed.
    */
   @Override
-  public boolean containsRow(@NullableDecl Object rowKey) {
+  public boolean containsRow(@CheckForNull Object rowKey) {
     return rowKeyToIndex.containsKey(rowKey);
   }
 
   @Override
-  public boolean containsValue(@NullableDecl Object value) {
-    for (V[] row : array) {
+  public boolean containsValue(@CheckForNull Object value) {
+    for (@Nullable V[] row : array) {
       for (V element : row) {
         if (Objects.equal(value, element)) {
           return true;
@@ -410,7 +435,8 @@ public boolean containsValue(@NullableDecl Object value) {
   }
 
   @Override
-  public V get(@NullableDecl Object rowKey, @NullableDecl Object columnKey) {
+  @CheckForNull
+  public V get(@CheckForNull Object rowKey, @CheckForNull Object columnKey) {
     Integer rowIndex = rowKeyToIndex.get(rowKey);
     Integer columnIndex = columnKeyToIndex.get(columnKey);
     return (rowIndex == null || columnIndex == null) ? null : at(rowIndex, columnIndex);
@@ -432,7 +458,8 @@ public boolean isEmpty() {
    */
   @CanIgnoreReturnValue
   @Override
-  public V put(R rowKey, C columnKey, @NullableDecl V value) {
+  @CheckForNull
+  public V put(R rowKey, C columnKey, @CheckForNull V value) {
     checkNotNull(rowKey);
     checkNotNull(columnKey);
     Integer rowIndex = rowKeyToIndex.get(rowKey);
@@ -458,7 +485,7 @@ public V put(R rowKey, C columnKey, @NullableDecl V value) {
    *     in {@link #rowKeySet()} or {@link #columnKeySet()}
    */
   @Override
-  public void putAll(Table<? extends R, ? extends C, ? extends V> table) {
+  public void putAll(Table<? extends R, ? extends C, ? extends @Nullable V> table) {
     super.putAll(table);
   }
 
@@ -472,7 +499,8 @@ public void putAll(Table<? extends R, ? extends C, ? extends V> table) {
   @CanIgnoreReturnValue
   @Override
   @Deprecated
-  public V remove(Object rowKey, Object columnKey) {
+  @CheckForNull
+  public V remove(@CheckForNull Object rowKey, @CheckForNull Object columnKey) {
     throw new UnsupportedOperationException();
   }
 
@@ -490,7 +518,8 @@ public V remove(Object rowKey, Object columnKey) {
    *     for the keys
    */
   @CanIgnoreReturnValue
-  public V erase(@NullableDecl Object rowKey, @NullableDecl Object columnKey) {
+  @CheckForNull
+  public V erase(@CheckForNull Object rowKey, @CheckForNull Object columnKey) {
     Integer rowIndex = rowKeyToIndex.get(rowKey);
     Integer columnIndex = columnKeyToIndex.get(columnKey);
     if (rowIndex == null || columnIndex == null) {
@@ -518,22 +547,22 @@ public int size() {
    * @return set of table cells consisting of row key / column key / value triplets
    */
   @Override
-  public Set<Cell<R, C, V>> cellSet() {
+  public Set<Cell<R, C, @Nullable V>> cellSet() {
     return super.cellSet();
   }
 
   @Override
-  Iterator<Cell<R, C, V>> cellIterator() {
-    return new AbstractIndexedListIterator<Cell<R, C, V>>(size()) {
+  Iterator<Cell<R, C, @Nullable V>> cellIterator() {
+    return new AbstractIndexedListIterator<Cell<R, C, @Nullable V>>(size()) {
       @Override
-      protected Cell<R, C, V> get(final int index) {
+      protected Cell<R, C, @Nullable V> get(final int index) {
         return getCell(index);
       }
     };
   }
 
-  private Cell<R, C, V> getCell(final int index) {
-    return new Tables.AbstractCell<R, C, V>() {
+  private Cell<R, C, @Nullable V> getCell(final int index) {
+    return new Tables.AbstractCell<R, C, @Nullable V>() {
       final int rowIndex = index / columnList.size();
       final int columnIndex = index % columnList.size();
 
@@ -548,12 +577,14 @@ public C getColumnKey() {
       }
 
       @Override
+      @CheckForNull
       public V getValue() {
         return at(rowIndex, columnIndex);
       }
     };
   }
 
+  @CheckForNull
   private V getValue(int index) {
     int rowIndex = index / columnList.size();
     int columnIndex = index % columnList.size();
@@ -572,13 +603,17 @@ private V getValue(int index) {
    * @return the corresponding map from row keys to values
    */
   @Override
-  public Map<R, V> column(C columnKey) {
+  public Map<R, @Nullable V> column(C columnKey) {
     checkNotNull(columnKey);
     Integer columnIndex = columnKeyToIndex.get(columnKey);
-    return (columnIndex == null) ? ImmutableMap.<R, V>of() : new Column(columnIndex);
+    if (columnIndex == null) {
+      return emptyMap();
+    } else {
+      return new Column(columnIndex);
+    }
   }
 
-  private class Column extends ArrayMap<R, V> {
+  private class Column extends ArrayMap<R, @Nullable V> {
     final int columnIndex;
 
     Column(int columnIndex) {
@@ -592,12 +627,14 @@ String getKeyRole() {
     }
 
     @Override
+    @CheckForNull
     V getValue(int index) {
       return at(index, columnIndex);
     }
 
     @Override
-    V setValue(int index, V newValue) {
+    @CheckForNull
+    V setValue(int index, @CheckForNull V newValue) {
       return set(index, columnIndex, newValue);
     }
   }
@@ -613,16 +650,16 @@ public ImmutableSet<C> columnKeySet() {
     return columnKeyToIndex.keySet();
   }
 
-  @NullableDecl private transient ColumnMap columnMap;
+  @CheckForNull private transient ColumnMap columnMap;
 
   @Override
-  public Map<C, Map<R, V>> columnMap() {
+  public Map<C, Map<R, @Nullable V>> columnMap() {
     ColumnMap map = columnMap;
     return (map == null) ? columnMap = new ColumnMap() : map;
   }
 
   @WeakOuter
-  private class ColumnMap extends ArrayMap<C, Map<R, V>> {
+  private class ColumnMap extends ArrayMap<C, Map<R, @Nullable V>> {
     private ColumnMap() {
       super(columnKeyToIndex);
     }
@@ -633,17 +670,18 @@ String getKeyRole() {
     }
 
     @Override
-    Map<R, V> getValue(int index) {
+    Map<R, @Nullable V> getValue(int index) {
       return new Column(index);
     }
 
     @Override
-    Map<R, V> setValue(int index, Map<R, V> newValue) {
+    Map<R, @Nullable V> setValue(int index, Map<R, @Nullable V> newValue) {
       throw new UnsupportedOperationException();
     }
 
     @Override
-    public Map<R, V> put(C key, Map<R, V> value) {
+    @CheckForNull
+    public Map<R, @Nullable V> put(C key, Map<R, @Nullable V> value) {
       throw new UnsupportedOperationException();
     }
   }
@@ -660,13 +698,17 @@ public Map<R, V> put(C key, Map<R, V> value) {
    * @return the corresponding map from column keys to values
    */
   @Override
-  public Map<C, V> row(R rowKey) {
+  public Map<C, @Nullable V> row(R rowKey) {
     checkNotNull(rowKey);
     Integer rowIndex = rowKeyToIndex.get(rowKey);
-    return (rowIndex == null) ? ImmutableMap.<C, V>of() : new Row(rowIndex);
+    if (rowIndex == null) {
+      return emptyMap();
+    } else {
+      return new Row(rowIndex);
+    }
   }
 
-  private class Row extends ArrayMap<C, V> {
+  private class Row extends ArrayMap<C, @Nullable V> {
     final int rowIndex;
 
     Row(int rowIndex) {
@@ -680,12 +722,14 @@ String getKeyRole() {
     }
 
     @Override
+    @CheckForNull
     V getValue(int index) {
       return at(rowIndex, index);
     }
 
     @Override
-    V setValue(int index, V newValue) {
+    @CheckForNull
+    V setValue(int index, @CheckForNull V newValue) {
       return set(rowIndex, index, newValue);
     }
   }
@@ -701,16 +745,16 @@ public ImmutableSet<R> rowKeySet() {
     return rowKeyToIndex.keySet();
   }
 
-  @NullableDecl private transient RowMap rowMap;
+  @CheckForNull private transient RowMap rowMap;
 
   @Override
-  public Map<R, Map<C, V>> rowMap() {
+  public Map<R, Map<C, @Nullable V>> rowMap() {
     RowMap map = rowMap;
     return (map == null) ? rowMap = new RowMap() : map;
   }
 
   @WeakOuter
-  private class RowMap extends ArrayMap<R, Map<C, V>> {
+  private class RowMap extends ArrayMap<R, Map<C, @Nullable V>> {
     private RowMap() {
       super(rowKeyToIndex);
     }
@@ -721,17 +765,18 @@ String getKeyRole() {
     }
 
     @Override
-    Map<C, V> getValue(int index) {
+    Map<C, @Nullable V> getValue(int index) {
       return new Row(index);
     }
 
     @Override
-    Map<C, V> setValue(int index, Map<C, V> newValue) {
+    Map<C, @Nullable V> setValue(int index, Map<C, @Nullable V> newValue) {
       throw new UnsupportedOperationException();
     }
 
     @Override
-    public Map<C, V> put(R key, Map<C, V> value) {
+    @CheckForNull
+    public Map<C, @Nullable V> put(R key, Map<C, @Nullable V> value) {
       throw new UnsupportedOperationException();
     }
   }
@@ -746,14 +791,15 @@ public Map<C, V> put(R key, Map<C, V> value) {
    * @return collection of values
    */
   @Override
-  public Collection<V> values() {
+  public Collection<@Nullable V> values() {
     return super.values();
   }
 
   @Override
-  Iterator<V> valuesIterator() {
-    return new AbstractIndexedListIterator<V>(size()) {
+  Iterator<@Nullable V> valuesIterator() {
+    return new AbstractIndexedListIterator<@Nullable V>(size()) {
       @Override
+      @CheckForNull
       protected V get(int index) {
         return getValue(index);
       }
diff --git a/android/guava/src/com/google/common/collect/BaseImmutableMultimap.java b/android/guava/src/com/google/common/collect/BaseImmutableMultimap.java
index 6ebdf14f52fa..2e69c2a92e39 100644
--- a/android/guava/src/com/google/common/collect/BaseImmutableMultimap.java
+++ b/android/guava/src/com/google/common/collect/BaseImmutableMultimap.java
@@ -22,4 +22,5 @@
  * retaining additional implementation details of {@link ImmutableMultimap}.
  */
 @GwtCompatible
+@ElementTypesAreNonnullByDefault
 abstract class BaseImmutableMultimap<K, V> extends AbstractMultimap<K, V> {}
diff --git a/android/guava/src/com/google/common/collect/BiMap.java b/android/guava/src/com/google/common/collect/BiMap.java
index 0fd75c0a1e5e..12eb4e3e1b61 100644
--- a/android/guava/src/com/google/common/collect/BiMap.java
+++ b/android/guava/src/com/google/common/collect/BiMap.java
@@ -20,7 +20,8 @@
 import com.google.errorprone.annotations.CanIgnoreReturnValue;
 import java.util.Map;
 import java.util.Set;
-import org.checkerframework.checker.nullness.compatqual.NullableDecl;
+import javax.annotation.CheckForNull;
+import org.checkerframework.checker.nullness.qual.Nullable;
 
 /**
  * A bimap (or "bidirectional map") is a map that preserves the uniqueness of its values as well as
@@ -28,13 +29,14 @@
  * bimap containing the same entries as this bimap but with reversed keys and values.
  *
  * <p>See the Guava User Guide article on <a href=
- * "https://github.com/google/guava/wiki/NewCollectionTypesExplained#bimap"> {@code BiMap}</a>.
+ * "https://github.com/google/guava/wiki/NewCollectionTypesExplained#bimap">{@code BiMap}</a>.
  *
  * @author Kevin Bourrillion
  * @since 2.0
  */
 @GwtCompatible
-public interface BiMap<K, V> extends Map<K, V> {
+@ElementTypesAreNonnullByDefault
+public interface BiMap<K extends @Nullable Object, V extends @Nullable Object> extends Map<K, V> {
   // Modification Operations
 
   /**
@@ -46,8 +48,8 @@ public interface BiMap<K, V> extends Map<K, V> {
    */
   @CanIgnoreReturnValue
   @Override
-  @NullableDecl
-  V put(@NullableDecl K key, @NullableDecl V value);
+  @CheckForNull
+  V put(@ParametricNullness K key, @ParametricNullness V value);
 
   /**
    * An alternate form of {@code put} that silently removes any existing entry with the value {@code
@@ -62,12 +64,14 @@ public interface BiMap<K, V> extends Map<K, V> {
    *
    * @param key the key with which the specified value is to be associated
    * @param value the value to be associated with the specified key
-   * @return the value which was previously associated with the key, which may be {@code null}, or
-   *     {@code null} if there was no previous entry
+   * @return the value that was previously associated with the key, or {@code null} if there was no
+   *     previous entry. (If the bimap contains null values, then {@code forcePut}, like {@code
+   *     put}, returns {@code null} both if the key is absent and if it is present with a null
+   *     value.)
    */
   @CanIgnoreReturnValue
-  @NullableDecl
-  V forcePut(@NullableDecl K key, @NullableDecl V value);
+  @CheckForNull
+  V forcePut(@ParametricNullness K key, @ParametricNullness V value);
 
   // Bulk Operations
 
diff --git a/android/guava/src/com/google/common/collect/BoundType.java b/android/guava/src/com/google/common/collect/BoundType.java
index ce038026a078..00ac08c5182c 100644
--- a/android/guava/src/com/google/common/collect/BoundType.java
+++ b/android/guava/src/com/google/common/collect/BoundType.java
@@ -24,6 +24,7 @@
  * @since 10.0
  */
 @GwtCompatible
+@ElementTypesAreNonnullByDefault
 public enum BoundType {
   /** The endpoint value <i>is not</i> considered part of the set ("exclusive"). */
   OPEN(false),
@@ -39,8 +40,4 @@ public enum BoundType {
   static BoundType forBoolean(boolean inclusive) {
     return inclusive ? CLOSED : OPEN;
   }
-
-  BoundType flip() {
-    return forBoolean(!inclusive);
-  }
 }
diff --git a/android/guava/src/com/google/common/collect/ByFunctionOrdering.java b/android/guava/src/com/google/common/collect/ByFunctionOrdering.java
index 9e8671b12583..43ebdddf62b3 100644
--- a/android/guava/src/com/google/common/collect/ByFunctionOrdering.java
+++ b/android/guava/src/com/google/common/collect/ByFunctionOrdering.java
@@ -22,14 +22,17 @@
 import com.google.common.base.Function;
 import com.google.common.base.Objects;
 import java.io.Serializable;
-import org.checkerframework.checker.nullness.compatqual.NullableDecl;
+import javax.annotation.CheckForNull;
+import org.checkerframework.checker.nullness.qual.Nullable;
 
 /**
  * An ordering that orders elements by applying an order to the result of a function on those
  * elements.
  */
 @GwtCompatible(serializable = true)
-final class ByFunctionOrdering<F, T> extends Ordering<F> implements Serializable {
+@ElementTypesAreNonnullByDefault
+final class ByFunctionOrdering<F extends @Nullable Object, T extends @Nullable Object>
+    extends Ordering<F> implements Serializable {
   final Function<F, ? extends T> function;
   final Ordering<T> ordering;
 
@@ -39,12 +42,12 @@ final class ByFunctionOrdering<F, T> extends Ordering<F> implements Serializable
   }
 
   @Override
-  public int compare(F left, F right) {
+  public int compare(@ParametricNullness F left, @ParametricNullness F right) {
     return ordering.compare(function.apply(left), function.apply(right));
   }
 
   @Override
-  public boolean equals(@NullableDecl Object object) {
+  public boolean equals(@CheckForNull Object object) {
     if (object == this) {
       return true;
     }
diff --git a/android/guava/src/com/google/common/collect/CartesianList.java b/android/guava/src/com/google/common/collect/CartesianList.java
index 63c7f1a3efe2..4c31b12998e5 100644
--- a/android/guava/src/com/google/common/collect/CartesianList.java
+++ b/android/guava/src/com/google/common/collect/CartesianList.java
@@ -22,7 +22,7 @@
 import java.util.List;
 import java.util.ListIterator;
 import java.util.RandomAccess;
-import org.checkerframework.checker.nullness.compatqual.NullableDecl;
+import javax.annotation.CheckForNull;
 
 /**
  * Implementation of {@link Lists#cartesianProduct(List)}.
@@ -30,6 +30,7 @@
  * @author Louis Wasserman
  */
 @GwtCompatible
+@ElementTypesAreNonnullByDefault
 final class CartesianList<E> extends AbstractList<List<E>> implements RandomAccess {
 
   private final transient ImmutableList<List<E>> axes;
@@ -44,7 +45,7 @@ static <E> List<List<E>> create(List<? extends List<? extends E>> lists) {
       }
       axesBuilder.add(copy);
     }
-    return new CartesianList<E>(axesBuilder.build());
+    return new CartesianList<>(axesBuilder.build());
   }
 
   CartesianList(ImmutableList<List<E>> axes) {
@@ -67,7 +68,7 @@ private int getAxisIndexForProductIndex(int index, int axis) {
   }
 
   @Override
-  public int indexOf(Object o) {
+  public int indexOf(@CheckForNull Object o) {
     if (!(o instanceof List)) {
       return -1;
     }
@@ -89,7 +90,7 @@ public int indexOf(Object o) {
   }
 
   @Override
-  public int lastIndexOf(Object o) {
+  public int lastIndexOf(@CheckForNull Object o) {
     if (!(o instanceof List)) {
       return -1;
     }
@@ -111,7 +112,7 @@ public int lastIndexOf(Object o) {
   }
 
   @Override
-  public ImmutableList<E> get(final int index) {
+  public ImmutableList<E> get(int index) {
     checkElementIndex(index, size());
     return new ImmutableList<E>() {
 
@@ -140,7 +141,7 @@ public int size() {
   }
 
   @Override
-  public boolean contains(@NullableDecl Object object) {
+  public boolean contains(@CheckForNull Object object) {
     if (!(object instanceof List)) {
       return false;
     }
diff --git a/android/guava/src/com/google/common/collect/ClassToInstanceMap.java b/android/guava/src/com/google/common/collect/ClassToInstanceMap.java
index 8d454c0c6869..9bd826fd92f6 100644
--- a/android/guava/src/com/google/common/collect/ClassToInstanceMap.java
+++ b/android/guava/src/com/google/common/collect/ClassToInstanceMap.java
@@ -20,7 +20,7 @@
 import com.google.errorprone.annotations.CanIgnoreReturnValue;
 import com.google.errorprone.annotations.DoNotMock;
 import java.util.Map;
-import org.checkerframework.checker.nullness.compatqual.NullableDecl;
+import javax.annotation.CheckForNull;
 
 /**
  * A map, each entry of which maps a Java <a href="http://tinyurl.com/2cmwkz">raw type</a> to an
@@ -30,8 +30,19 @@
  * <p>Like any other {@code Map<Class, Object>}, this map may contain entries for primitive types,
  * and a primitive type and its corresponding wrapper type may map to different values.
  *
+ * <p>This class's support for {@code null} requires some explanation: From release 31.0 onward,
+ * Guava specifies the nullness of its types through annotations. In the case of {@code
+ * ClassToInstanceMap}, it specifies that both the key and value types are restricted to
+ * non-nullable types. This specification is reasonable for <i>keys</i>, which must be non-null
+ * classes. This is in contrast to the specification for <i>values</i>: Null values <i>are</i>
+ * supported by the implementation {@link MutableClassToInstanceMap}, even though that
+ * implementation and this interface specify otherwise. Thus, if you use a nullness checker, you can
+ * safely suppress any warnings it produces when you write null values into a {@code
+ * MutableClassToInstanceMap}. Just be sure to be prepared for null values when reading from it,
+ * since nullness checkers will assume that vaules are non-null then, too.
+ *
  * <p>See the Guava User Guide article on <a href=
- * "https://github.com/google/guava/wiki/NewCollectionTypesExplained#classtoinstancemap"> {@code
+ * "https://github.com/google/guava/wiki/NewCollectionTypesExplained#classtoinstancemap">{@code
  * ClassToInstanceMap}</a>.
  *
  * <p>To map a generic type to an instance of that type, use {@link
@@ -43,12 +54,18 @@
  */
 @DoNotMock("Use ImmutableClassToInstanceMap or MutableClassToInstanceMap")
 @GwtCompatible
+@ElementTypesAreNonnullByDefault
+// If we ever support non-null projections (https://github.com/jspecify/jspecify/issues/86), we
+// we might annotate this as...
+// ClassToInstanceMap<B extends @Nullable Object> extends Map<Class<? extends @Nonnull B>, B>
+// ...and change its methods similarly (<T extends @Nonnull B> or Class<@Nonnull T>).
 public interface ClassToInstanceMap<B> extends Map<Class<? extends B>, B> {
   /**
    * Returns the value the specified class is mapped to, or {@code null} if no entry for this class
    * is present. This will only return a value that was bound to this specific class, not a value
    * that may have been bound to a subtype.
    */
+  @CheckForNull
   <T extends B> T getInstance(Class<T> type);
 
   /**
@@ -59,5 +76,6 @@ public interface ClassToInstanceMap<B> extends Map<Class<? extends B>, B> {
    *     null} if there was no previous entry.
    */
   @CanIgnoreReturnValue
-  <T extends B> T putInstance(Class<T> type, @NullableDecl T value);
+  @CheckForNull
+  <T extends B> T putInstance(Class<T> type, T value);
 }
diff --git a/android/guava/src/com/google/common/collect/CollectPreconditions.java b/android/guava/src/com/google/common/collect/CollectPreconditions.java
index 98b30c6d5e7b..c649b03233e3 100644
--- a/android/guava/src/com/google/common/collect/CollectPreconditions.java
+++ b/android/guava/src/com/google/common/collect/CollectPreconditions.java
@@ -23,6 +23,7 @@
 
 /** Precondition checks useful in collection implementations. */
 @GwtCompatible
+@ElementTypesAreNonnullByDefault
 final class CollectPreconditions {
 
   static void checkEntryNotNull(Object key, Object value) {
diff --git a/android/guava/src/com/google/common/collect/Collections2.java b/android/guava/src/com/google/common/collect/Collections2.java
index 56b7a5b1d5cd..8d799d5932b8 100644
--- a/android/guava/src/com/google/common/collect/Collections2.java
+++ b/android/guava/src/com/google/common/collect/Collections2.java
@@ -19,6 +19,7 @@
 import static com.google.common.base.Preconditions.checkArgument;
 import static com.google.common.base.Preconditions.checkNotNull;
 import static com.google.common.collect.CollectPreconditions.checkNonnegative;
+import static java.util.Objects.requireNonNull;
 
 import com.google.common.annotations.Beta;
 import com.google.common.annotations.GwtCompatible;
@@ -35,7 +36,8 @@
 import java.util.Comparator;
 import java.util.Iterator;
 import java.util.List;
-import org.checkerframework.checker.nullness.compatqual.NullableDecl;
+import javax.annotation.CheckForNull;
+import org.checkerframework.checker.nullness.qual.Nullable;
 
 /**
  * Provides static methods for working with {@code Collection} instances.
@@ -51,6 +53,7 @@
  * @since 2.0
  */
 @GwtCompatible
+@ElementTypesAreNonnullByDefault
 public final class Collections2 {
   private Collections2() {}
 
@@ -81,7 +84,8 @@ private Collections2() {}
    */
   // TODO(kevinb): how can we omit that Iterables link when building gwt
   // javadoc?
-  public static <E> Collection<E> filter(Collection<E> unfiltered, Predicate<? super E> predicate) {
+  public static <E extends @Nullable Object> Collection<E> filter(
+      Collection<E> unfiltered, Predicate<? super E> predicate) {
     if (unfiltered instanceof FilteredCollection) {
       // Support clear(), removeAll(), and retainAll() when filtering a filtered
       // collection.
@@ -95,7 +99,7 @@ public static <E> Collection<E> filter(Collection<E> unfiltered, Predicate<? sup
    * Delegates to {@link Collection#contains}. Returns {@code false} if the {@code contains} method
    * throws a {@code ClassCastException} or {@code NullPointerException}.
    */
-  static boolean safeContains(Collection<?> collection, @NullableDecl Object object) {
+  static boolean safeContains(Collection<?> collection, @CheckForNull Object object) {
     checkNotNull(collection);
     try {
       return collection.contains(object);
@@ -108,7 +112,7 @@ static boolean safeContains(Collection<?> collection, @NullableDecl Object objec
    * Delegates to {@link Collection#remove}. Returns {@code false} if the {@code remove} method
    * throws a {@code ClassCastException} or {@code NullPointerException}.
    */
-  static boolean safeRemove(Collection<?> collection, @NullableDecl Object object) {
+  static boolean safeRemove(Collection<?> collection, @CheckForNull Object object) {
     checkNotNull(collection);
     try {
       return collection.remove(object);
@@ -117,7 +121,7 @@ static boolean safeRemove(Collection<?> collection, @NullableDecl Object object)
     }
   }
 
-  static class FilteredCollection<E> extends AbstractCollection<E> {
+  static class FilteredCollection<E extends @Nullable Object> extends AbstractCollection<E> {
     final Collection<E> unfiltered;
     final Predicate<? super E> predicate;
 
@@ -132,7 +136,7 @@ FilteredCollection<E> createCombined(Predicate<? super E> newPredicate) {
     }
 
     @Override
-    public boolean add(E element) {
+    public boolean add(@ParametricNullness E element) {
       checkArgument(predicate.apply(element));
       return unfiltered.add(element);
     }
@@ -151,7 +155,7 @@ public void clear() {
     }
 
     @Override
-    public boolean contains(@NullableDecl Object element) {
+    public boolean contains(@CheckForNull Object element) {
       if (safeContains(unfiltered, element)) {
         @SuppressWarnings("unchecked") // element is in unfiltered, so it must be an E
         E e = (E) element;
@@ -176,7 +180,7 @@ public Iterator<E> iterator() {
     }
 
     @Override
-    public boolean remove(Object element) {
+    public boolean remove(@CheckForNull Object element) {
       return contains(element) && unfiltered.remove(element);
     }
 
@@ -220,13 +224,14 @@ public int size() {
     }
 
     @Override
-    public Object[] toArray() {
+    public @Nullable Object[] toArray() {
       // creating an ArrayList so filtering happens once
       return Lists.newArrayList(iterator()).toArray();
     }
 
     @Override
-    public <T> T[] toArray(T[] array) {
+    @SuppressWarnings("nullness") // b/192354773 in our checker affects toArray declarations
+    public <T extends @Nullable Object> T[] toArray(T[] array) {
       return Lists.newArrayList(iterator()).toArray(array);
     }
   }
@@ -250,12 +255,13 @@ public <T> T[] toArray(T[] array) {
    *
    * <p><b>{@code Stream} equivalent:</b> {@link java.util.stream.Stream#map Stream.map}.
    */
-  public static <F, T> Collection<T> transform(
+  public static <F extends @Nullable Object, T extends @Nullable Object> Collection<T> transform(
       Collection<F> fromCollection, Function<? super F, T> function) {
     return new TransformedCollection<>(fromCollection, function);
   }
 
-  static class TransformedCollection<F, T> extends AbstractCollection<T> {
+  static class TransformedCollection<F extends @Nullable Object, T extends @Nullable Object>
+      extends AbstractCollection<T> {
     final Collection<F> fromCollection;
     final Function<? super F, ? extends T> function;
 
@@ -466,7 +472,7 @@ public Iterator<List<E>> iterator() {
     }
 
     @Override
-    public boolean contains(@NullableDecl Object obj) {
+    public boolean contains(@CheckForNull Object obj) {
       if (obj instanceof List) {
         List<?> list = (List<?>) obj;
         return isPermutation(inputList, list);
@@ -481,7 +487,7 @@ public String toString() {
   }
 
   private static final class OrderedPermutationIterator<E> extends AbstractIterator<List<E>> {
-    @NullableDecl List<E> nextPermutation;
+    @CheckForNull List<E> nextPermutation;
     final Comparator<? super E> comparator;
 
     OrderedPermutationIterator(List<E> list, Comparator<? super E> comparator) {
@@ -490,6 +496,7 @@ private static final class OrderedPermutationIterator<E> extends AbstractIterato
     }
 
     @Override
+    @CheckForNull
     protected List<E> computeNext() {
       if (nextPermutation == null) {
         return endOfData();
@@ -505,6 +512,11 @@ void calculateNextPermutation() {
         nextPermutation = null;
         return;
       }
+      /*
+       * requireNonNull is safe because we don't clear nextPermutation until we're done calling this
+       * method.
+       */
+      requireNonNull(nextPermutation);
 
       int l = findNextL(j);
       Collections.swap(nextPermutation, j, l);
@@ -513,6 +525,11 @@ void calculateNextPermutation() {
     }
 
     int findNextJ() {
+      /*
+       * requireNonNull is safe because we don't clear nextPermutation until we're done calling this
+       * method.
+       */
+      requireNonNull(nextPermutation);
       for (int k = nextPermutation.size() - 2; k >= 0; k--) {
         if (comparator.compare(nextPermutation.get(k), nextPermutation.get(k + 1)) < 0) {
           return k;
@@ -522,6 +539,11 @@ int findNextJ() {
     }
 
     int findNextL(int j) {
+      /*
+       * requireNonNull is safe because we don't clear nextPermutation until we're done calling this
+       * method.
+       */
+      requireNonNull(nextPermutation);
       E ak = nextPermutation.get(j);
       for (int l = nextPermutation.size() - 1; l > j; l--) {
         if (comparator.compare(ak, nextPermutation.get(l)) < 0) {
@@ -577,7 +599,7 @@ public Iterator<List<E>> iterator() {
     }
 
     @Override
-    public boolean contains(@NullableDecl Object obj) {
+    public boolean contains(@CheckForNull Object obj) {
       if (obj instanceof List) {
         List<?> list = (List<?>) obj;
         return isPermutation(inputList, list);
@@ -608,6 +630,7 @@ private static class PermutationIterator<E> extends AbstractIterator<List<E>> {
     }
 
     @Override
+    @CheckForNull
     protected List<E> computeNext() {
       if (j <= 0) {
         return endOfData();
@@ -672,7 +695,8 @@ private static boolean isPermutation(List<?> first, List<?> second) {
     return true;
   }
 
-  private static <E> ObjectCountHashMap<E> counts(Collection<E> collection) {
+  private static <E extends @Nullable Object> ObjectCountHashMap<E> counts(
+      Collection<E> collection) {
     ObjectCountHashMap<E> map = new ObjectCountHashMap<>();
     for (E e : collection) {
       map.put(e, map.get(e) + 1);
diff --git a/android/guava/src/com/google/common/collect/CompactHashMap.java b/android/guava/src/com/google/common/collect/CompactHashMap.java
index 1fa4f96f0762..e70596dd222d 100644
--- a/android/guava/src/com/google/common/collect/CompactHashMap.java
+++ b/android/guava/src/com/google/common/collect/CompactHashMap.java
@@ -19,6 +19,9 @@
 import static com.google.common.collect.CollectPreconditions.checkRemove;
 import static com.google.common.collect.CompactHashing.UNSET;
 import static com.google.common.collect.Hashing.smearedHash;
+import static com.google.common.collect.NullnessCasts.uncheckedCastNullableTToT;
+import static com.google.common.collect.NullnessCasts.unsafeNull;
+import static java.util.Objects.requireNonNull;
 
 import com.google.common.annotations.GwtIncompatible;
 import com.google.common.annotations.VisibleForTesting;
@@ -43,7 +46,8 @@
 import java.util.Map;
 import java.util.NoSuchElementException;
 import java.util.Set;
-import org.checkerframework.checker.nullness.compatqual.NullableDecl;
+import javax.annotation.CheckForNull;
+import org.checkerframework.checker.nullness.qual.Nullable;
 
 /**
  * CompactHashMap is an implementation of a Map. All optional operations (put and remove) are
@@ -72,7 +76,9 @@
  * @author Jon Noack
  */
 @GwtIncompatible // not worth using in GWT for now
-class CompactHashMap<K, V> extends AbstractMap<K, V> implements Serializable {
+@ElementTypesAreNonnullByDefault
+class CompactHashMap<K extends @Nullable Object, V extends @Nullable Object>
+    extends AbstractMap<K, V> implements Serializable {
   /*
    * TODO: Make this a drop-in replacement for j.u. versions, actually drop them in, and test the
    * world. Figure out what sort of space-time tradeoff we're actually going to get here with the
@@ -82,7 +88,8 @@ class CompactHashMap<K, V> extends AbstractMap<K, V> implements Serializable {
    */
 
   /** Creates an empty {@code CompactHashMap} instance. */
-  public static <K, V> CompactHashMap<K, V> create() {
+  public static <K extends @Nullable Object, V extends @Nullable Object>
+      CompactHashMap<K, V> create() {
     return new CompactHashMap<>();
   }
 
@@ -95,7 +102,8 @@ public static <K, V> CompactHashMap<K, V> create() {
    *     elements without resizing
    * @throws IllegalArgumentException if {@code expectedSize} is negative
    */
-  public static <K, V> CompactHashMap<K, V> createWithExpectedSize(int expectedSize) {
+  public static <K extends @Nullable Object, V extends @Nullable Object>
+      CompactHashMap<K, V> createWithExpectedSize(int expectedSize) {
     return new CompactHashMap<>(expectedSize);
   }
 
@@ -115,6 +123,46 @@ public static <K, V> CompactHashMap<K, V> createWithExpectedSize(int expectedSiz
    */
   private static final int MAX_HASH_BUCKET_LENGTH = 9;
 
+  // The way the `table`, `entries`, `keys`, and `values` arrays work together is as follows.
+  //
+  // The `table` array always has a size that is a power of 2. The hashcode of a key in the map
+  // is masked in order to correspond to the current table size. For example, if the table size
+  // is 128 then the mask is 127 == 0x7f, keeping the bottom 7 bits of the hash value.
+  // If a key hashes to 0x89abcdef the mask reduces it to 0x89abcdef & 0x7f == 0x6f. We'll call this
+  // the "short hash".
+  //
+  // The `keys`, `values`, and `entries` arrays always have the same size as each other. They can be
+  // seen as fields of an imaginary `Entry` object like this:
+  //
+  // class Entry {
+  //    int hash;
+  //    Entry next;
+  //    K key;
+  //    V value;
+  // }
+  //
+  // The imaginary `hash` and `next` values are combined into a single `int` value in the `entries`
+  // array. The top bits of this value are the remaining bits of the hash value that were not used
+  // in the short hash. We saw that a mask of 0x7f would keep the 7-bit value 0x6f from a full
+  // hashcode of 0x89abcdef. The imaginary `hash` value would then be the remaining top 25 bits,
+  // 0x89abcd80. To this is added (or'd) the `next` value, which is an index within `entries`
+  // (and therefore within `keys` and `values`) of another entry that has the same short hash
+  // value. In our example, it would be another entry for a key whose short hash is also 0x6f.
+  //
+  // Essentially, then, `table[h]` gives us the start of a linked list in `entries`, where every
+  // element of the list has the short hash value h.
+  //
+  // A wrinkle here is that the value 0 (called UNSET in the code) is used as the equivalent of a
+  // null pointer. If `table[h] == 0` that means there are no keys in the map whose short hash is h.
+  // If the `next` bits in `entries[i]` are 0 that means there are no further entries for the given
+  // short hash. But 0 is also a valid index in `entries`, so we add 1 to these indices before
+  // putting them in `table` or in `next` bits, and subtract 1 again when we need an index value.
+  //
+  // The elements of `keys`, `values`, and `entries` are added sequentially, so that elements 0 to
+  // `size() - 1` are used and remaining elements are not. This makes iteration straightforward.
+  // Removing an entry generally involves moving the last element of each array to where the removed
+  // entry was, and adjusting index links accordingly.
+
   /**
    * The hashtable object. This can be either:
    *
@@ -134,7 +182,7 @@ public static <K, V> CompactHashMap<K, V> createWithExpectedSize(int expectedSiz
    *   <li>null, if no entries have yet been added to the map
    * </ul>
    */
-  @NullableDecl private transient Object table;
+  @CheckForNull private transient Object table;
 
   /**
    * Contains the logical entries, in the range of [0, size()). The high bits of each int are the
@@ -144,32 +192,38 @@ public static <K, V> CompactHashMap<K, V> createWithExpectedSize(int expectedSiz
    *
    * <pre>
    * hash  = aaaaaaaa
-   * mask  = 0000ffff
-   * next  = 0000bbbb
-   * entry = aaaabbbb
+   * mask  = 00000fff
+   * next  = 00000bbb
+   * entry = aaaaabbb
    * </pre>
    *
    * <p>The pointers in [size(), entries.length) are all "null" (UNSET).
    */
-  @VisibleForTesting @NullableDecl transient int[] entries;
+  @VisibleForTesting @CheckForNull transient int[] entries;
 
   /**
    * The keys of the entries in the map, in the range of [0, size()). The keys in [size(),
    * keys.length) are all {@code null}.
    */
-  @VisibleForTesting @NullableDecl transient Object[] keys;
+  @VisibleForTesting @CheckForNull transient @Nullable Object[] keys;
 
   /**
    * The values of the entries in the map, in the range of [0, size()). The values in [size(),
    * values.length) are all {@code null}.
    */
-  @VisibleForTesting @NullableDecl transient Object[] values;
+  @VisibleForTesting @CheckForNull transient @Nullable Object[] values;
 
   /**
    * Keeps track of metadata like the number of hash table bits and modifications of this data
    * structure (to make it possible to throw ConcurrentModificationException in the iterator). Note
    * that we choose not to make this volatile, so we do less of a "best effort" to track such
    * errors, for better performance.
+   *
+   * <p>For a new instance, where the arrays above have not yet been allocated, the value of {@code
+   * metadata} is the size that the arrays should be allocated with. Once the arrays have been
+   * allocated, the value of {@code metadata} combines the number of bits in the "short hash", in
+   * its bottom {@value CompactHashing#HASH_TABLE_BITS_MAX_BITS} bits, with a modification count in
+   * the remaining bits that is used to detect concurrent modification during iteration.
    */
   private transient int metadata;
 
@@ -223,7 +277,7 @@ int allocArrays() {
 
   @SuppressWarnings("unchecked")
   @VisibleForTesting
-  @NullableDecl
+  @CheckForNull
   Map<K, V> delegateOrNull() {
     if (table instanceof Map) {
       return (Map<K, V>) table;
@@ -235,13 +289,12 @@ Map<K, V> createHashFloodingResistantDelegate(int tableSize) {
     return new LinkedHashMap<>(tableSize, 1.0f);
   }
 
-  @SuppressWarnings("unchecked")
   @VisibleForTesting
   @CanIgnoreReturnValue
   Map<K, V> convertToHashFloodingResistantImplementation() {
     Map<K, V> newDelegate = createHashFloodingResistantDelegate(hashTableMask() + 1);
     for (int i = firstEntryIndex(); i >= 0; i = getSuccessor(i)) {
-      newDelegate.put((K) keys[i], (V) values[i]);
+      newDelegate.put(key(i), value(i));
     }
     this.table = newDelegate;
     this.entries = null;
@@ -277,31 +330,31 @@ void accessEntry(int index) {
 
   @CanIgnoreReturnValue
   @Override
-  @NullableDecl
-  public V put(@NullableDecl K key, @NullableDecl V value) {
+  @CheckForNull
+  public V put(@ParametricNullness K key, @ParametricNullness V value) {
     if (needsAllocArrays()) {
       allocArrays();
     }
-    @NullableDecl Map<K, V> delegate = delegateOrNull();
+    Map<K, V> delegate = delegateOrNull();
     if (delegate != null) {
       return delegate.put(key, value);
     }
-    int[] entries = this.entries;
-    Object[] keys = this.keys;
-    Object[] values = this.values;
+    int[] entries = requireEntries();
+    @Nullable Object[] keys = requireKeys();
+    @Nullable Object[] values = requireValues();
 
     int newEntryIndex = this.size; // current size, and pointer to the entry to be appended
     int newSize = newEntryIndex + 1;
     int hash = smearedHash(key);
     int mask = hashTableMask();
     int tableIndex = hash & mask;
-    int next = CompactHashing.tableGet(table, tableIndex);
+    int next = CompactHashing.tableGet(requireTable(), tableIndex);
     if (next == UNSET) { // uninitialized bucket
       if (newSize > mask) {
         // Resize and add new entry
         mask = resizeTable(mask, CompactHashing.newCapacity(mask), hash, newEntryIndex);
       } else {
-        CompactHashing.tableSet(table, tableIndex, newEntryIndex + 1);
+        CompactHashing.tableSet(requireTable(), tableIndex, newEntryIndex + 1);
       }
     } else {
       int entryIndex;
@@ -314,7 +367,6 @@ public V put(@NullableDecl K key, @NullableDecl V value) {
         if (CompactHashing.getHashPrefix(entry, mask) == hashPrefix
             && Objects.equal(key, keys[entryIndex])) {
           @SuppressWarnings("unchecked") // known to be a V
-          @NullableDecl
           V oldValue = (V) values[entryIndex];
 
           values[entryIndex] = value;
@@ -346,15 +398,16 @@ public V put(@NullableDecl K key, @NullableDecl V value) {
   /**
    * Creates a fresh entry with the specified object at the specified position in the entry arrays.
    */
-  void insertEntry(int entryIndex, @NullableDecl K key, @NullableDecl V value, int hash, int mask) {
-    this.entries[entryIndex] = CompactHashing.maskCombine(hash, UNSET, mask);
-    this.keys[entryIndex] = key;
-    this.values[entryIndex] = value;
+  void insertEntry(
+      int entryIndex, @ParametricNullness K key, @ParametricNullness V value, int hash, int mask) {
+    this.setEntry(entryIndex, CompactHashing.maskCombine(hash, UNSET, mask));
+    this.setKey(entryIndex, key);
+    this.setValue(entryIndex, value);
   }
 
   /** Resizes the entries storage if necessary. */
   private void resizeMeMaybe(int newSize) {
-    int entriesSize = entries.length;
+    int entriesSize = requireEntries().length;
     if (newSize > entriesSize) {
       // 1.5x but round up to nearest odd (this is optimal for memory consumption on Android)
       int newCapacity =
@@ -370,13 +423,13 @@ private void resizeMeMaybe(int newSize) {
    * the current capacity.
    */
   void resizeEntries(int newCapacity) {
-    this.entries = Arrays.copyOf(entries, newCapacity);
-    this.keys = Arrays.copyOf(keys, newCapacity);
-    this.values = Arrays.copyOf(values, newCapacity);
+    this.entries = Arrays.copyOf(requireEntries(), newCapacity);
+    this.keys = Arrays.copyOf(requireKeys(), newCapacity);
+    this.values = Arrays.copyOf(requireValues(), newCapacity);
   }
 
   @CanIgnoreReturnValue
-  private int resizeTable(int mask, int newCapacity, int targetHash, int targetEntryIndex) {
+  private int resizeTable(int oldMask, int newCapacity, int targetHash, int targetEntryIndex) {
     Object newTable = CompactHashing.createTable(newCapacity);
     int newMask = newCapacity - 1;
 
@@ -385,25 +438,35 @@ private int resizeTable(int mask, int newCapacity, int targetHash, int targetEnt
       CompactHashing.tableSet(newTable, targetHash & newMask, targetEntryIndex + 1);
     }
 
-    Object table = this.table;
-    int[] entries = this.entries;
-
-    // Loop over current hashtable
-    for (int tableIndex = 0; tableIndex <= mask; tableIndex++) {
-      int next = CompactHashing.tableGet(table, tableIndex);
-      while (next != UNSET) {
-        int entryIndex = next - 1;
-        int entry = entries[entryIndex];
-
-        // Rebuild hash using entry hashPrefix and tableIndex ("hashSuffix")
-        int hash = CompactHashing.getHashPrefix(entry, mask) | tableIndex;
+    Object oldTable = requireTable();
+    int[] entries = requireEntries();
+
+    // Loop over `oldTable` to construct its replacement, ``newTable`. The entries do not move, so
+    // the `keys` and `values` arrays do not need to change. But because the "short hash" now has a
+    // different number of bits, we must rewrite each element of `entries` so that its contribution
+    // to the full hashcode reflects the change, and so that its `next` link corresponds to the new
+    // linked list of entries with the new short hash.
+    for (int oldTableIndex = 0; oldTableIndex <= oldMask; oldTableIndex++) {
+      int oldNext = CompactHashing.tableGet(oldTable, oldTableIndex);
+      // Each element of `oldTable` is the head of a (possibly empty) linked list of elements in
+      // `entries`. The `oldNext` loop is going to traverse that linked list.
+      // We need to rewrite the `next` link of each of the elements so that it is in the appropriate
+      // linked list starting from `newTable`. In general, each element from the old linked list
+      // belongs to a different linked list from `newTable`. We insert each element in turn at the
+      // head of its appropriate `newTable` linked list.
+      while (oldNext != UNSET) {
+        int entryIndex = oldNext - 1;
+        int oldEntry = entries[entryIndex];
+
+        // Rebuild the full 32-bit hash using entry hashPrefix and oldTableIndex ("hashSuffix").
+        int hash = CompactHashing.getHashPrefix(oldEntry, oldMask) | oldTableIndex;
 
         int newTableIndex = hash & newMask;
         int newNext = CompactHashing.tableGet(newTable, newTableIndex);
-        CompactHashing.tableSet(newTable, newTableIndex, next);
+        CompactHashing.tableSet(newTable, newTableIndex, oldNext);
         entries[entryIndex] = CompactHashing.maskCombine(hash, newNext, newMask);
 
-        next = CompactHashing.getNext(entry, mask);
+        oldNext = CompactHashing.getNext(oldEntry, oldMask);
       }
     }
 
@@ -412,22 +475,22 @@ private int resizeTable(int mask, int newCapacity, int targetHash, int targetEnt
     return newMask;
   }
 
-  private int indexOf(@NullableDecl Object key) {
+  private int indexOf(@CheckForNull Object key) {
     if (needsAllocArrays()) {
       return -1;
     }
     int hash = smearedHash(key);
     int mask = hashTableMask();
-    int next = CompactHashing.tableGet(table, hash & mask);
+    int next = CompactHashing.tableGet(requireTable(), hash & mask);
     if (next == UNSET) {
       return -1;
     }
     int hashPrefix = CompactHashing.getHashPrefix(hash, mask);
     do {
       int entryIndex = next - 1;
-      int entry = entries[entryIndex];
+      int entry = entry(entryIndex);
       if (CompactHashing.getHashPrefix(entry, mask) == hashPrefix
-          && Objects.equal(key, keys[entryIndex])) {
+          && Objects.equal(key, key(entryIndex))) {
         return entryIndex;
       }
       next = CompactHashing.getNext(entry, mask);
@@ -436,15 +499,15 @@ private int indexOf(@NullableDecl Object key) {
   }
 
   @Override
-  public boolean containsKey(@NullableDecl Object key) {
-    @NullableDecl Map<K, V> delegate = delegateOrNull();
+  public boolean containsKey(@CheckForNull Object key) {
+    Map<K, V> delegate = delegateOrNull();
     return (delegate != null) ? delegate.containsKey(key) : indexOf(key) != -1;
   }
 
-  @SuppressWarnings("unchecked") // known to be a V
   @Override
-  public V get(@NullableDecl Object key) {
-    @NullableDecl Map<K, V> delegate = delegateOrNull();
+  @CheckForNull
+  public V get(@CheckForNull Object key) {
+    Map<K, V> delegate = delegateOrNull();
     if (delegate != null) {
       return delegate.get(key);
     }
@@ -453,15 +516,15 @@ public V get(@NullableDecl Object key) {
       return null;
     }
     accessEntry(index);
-    return (V) values[index];
+    return value(index);
   }
 
   @CanIgnoreReturnValue
   @SuppressWarnings("unchecked") // known to be a V
   @Override
-  @NullableDecl
-  public V remove(@NullableDecl Object key) {
-    @NullableDecl Map<K, V> delegate = delegateOrNull();
+  @CheckForNull
+  public V remove(@CheckForNull Object key) {
+    Map<K, V> delegate = delegateOrNull();
     if (delegate != null) {
       return delegate.remove(key);
     }
@@ -469,20 +532,25 @@ public V remove(@NullableDecl Object key) {
     return (oldValue == NOT_FOUND) ? null : (V) oldValue;
   }
 
-  @NullableDecl
-  private Object removeHelper(@NullableDecl Object key) {
+  private @Nullable Object removeHelper(@CheckForNull Object key) {
     if (needsAllocArrays()) {
       return NOT_FOUND;
     }
     int mask = hashTableMask();
     int index =
         CompactHashing.remove(
-            key, /* value= */ null, mask, table, entries, keys, /* values= */ null);
+            key,
+            /* value= */ null,
+            mask,
+            requireTable(),
+            requireEntries(),
+            requireKeys(),
+            /* values= */ null);
     if (index == -1) {
       return NOT_FOUND;
     }
 
-    @NullableDecl Object oldValue = values[index];
+    Object oldValue = value(index);
 
     moveLastEntry(index, mask);
     size--;
@@ -495,10 +563,14 @@ private Object removeHelper(@NullableDecl Object key) {
    * Moves the last entry in the entry array into {@code dstIndex}, and nulls out its old position.
    */
   void moveLastEntry(int dstIndex, int mask) {
+    Object table = requireTable();
+    int[] entries = requireEntries();
+    @Nullable Object[] keys = requireKeys();
+    @Nullable Object[] values = requireValues();
     int srcIndex = size() - 1;
     if (dstIndex < srcIndex) {
       // move last entry to deleted spot
-      @NullableDecl Object key = keys[srcIndex];
+      Object key = keys[srcIndex];
       keys[dstIndex] = key;
       values[dstIndex] = values[srcIndex];
       keys[srcIndex] = null;
@@ -551,7 +623,7 @@ int adjustAfterRemove(int indexBeforeRemove, @SuppressWarnings("unused") int ind
     return indexBeforeRemove - 1;
   }
 
-  private abstract class Itr<T> implements Iterator<T> {
+  private abstract class Itr<T extends @Nullable Object> implements Iterator<T> {
     int expectedMetadata = metadata;
     int currentIndex = firstEntryIndex();
     int indexToRemove = -1;
@@ -561,9 +633,11 @@ public boolean hasNext() {
       return currentIndex >= 0;
     }
 
+    @ParametricNullness
     abstract T getOutput(int entry);
 
     @Override
+    @ParametricNullness
     public T next() {
       checkForConcurrentModification();
       if (!hasNext()) {
@@ -580,7 +654,7 @@ public void remove() {
       checkForConcurrentModification();
       checkRemove(indexToRemove >= 0);
       incrementExpectedModCount();
-      CompactHashMap.this.remove(keys[indexToRemove]);
+      CompactHashMap.this.remove(key(indexToRemove));
       currentIndex = adjustAfterRemove(currentIndex, indexToRemove);
       indexToRemove = -1;
     }
@@ -596,7 +670,7 @@ private void checkForConcurrentModification() {
     }
   }
 
-  @NullableDecl private transient Set<K> keySetView;
+  @CheckForNull private transient Set<K> keySetView;
 
   @Override
   public Set<K> keySet() {
@@ -615,13 +689,13 @@ public int size() {
     }
 
     @Override
-    public boolean contains(Object o) {
+    public boolean contains(@CheckForNull Object o) {
       return CompactHashMap.this.containsKey(o);
     }
 
     @Override
-    public boolean remove(@NullableDecl Object o) {
-      @NullableDecl Map<K, V> delegate = delegateOrNull();
+    public boolean remove(@CheckForNull Object o) {
+      Map<K, V> delegate = delegateOrNull();
       return (delegate != null)
           ? delegate.keySet().remove(o)
           : CompactHashMap.this.removeHelper(o) != NOT_FOUND;
@@ -639,20 +713,20 @@ public void clear() {
   }
 
   Iterator<K> keySetIterator() {
-    @NullableDecl Map<K, V> delegate = delegateOrNull();
+    Map<K, V> delegate = delegateOrNull();
     if (delegate != null) {
       return delegate.keySet().iterator();
     }
     return new Itr<K>() {
-      @SuppressWarnings("unchecked") // known to be a K
       @Override
+      @ParametricNullness
       K getOutput(int entry) {
-        return (K) keys[entry];
+        return key(entry);
       }
     };
   }
 
-  @NullableDecl private transient Set<Entry<K, V>> entrySetView;
+  @CheckForNull private transient Set<Entry<K, V>> entrySetView;
 
   @Override
   public Set<Entry<K, V>> entrySet() {
@@ -682,21 +756,21 @@ public Iterator<Entry<K, V>> iterator() {
     }
 
     @Override
-    public boolean contains(@NullableDecl Object o) {
-      @NullableDecl Map<K, V> delegate = delegateOrNull();
+    public boolean contains(@CheckForNull Object o) {
+      Map<K, V> delegate = delegateOrNull();
       if (delegate != null) {
         return delegate.entrySet().contains(o);
       } else if (o instanceof Entry) {
         Entry<?, ?> entry = (Entry<?, ?>) o;
         int index = indexOf(entry.getKey());
-        return index != -1 && Objects.equal(values[index], entry.getValue());
+        return index != -1 && Objects.equal(value(index), entry.getValue());
       }
       return false;
     }
 
     @Override
-    public boolean remove(@NullableDecl Object o) {
-      @NullableDecl Map<K, V> delegate = delegateOrNull();
+    public boolean remove(@CheckForNull Object o) {
+      Map<K, V> delegate = delegateOrNull();
       if (delegate != null) {
         return delegate.entrySet().remove(o);
       } else if (o instanceof Entry) {
@@ -707,7 +781,13 @@ public boolean remove(@NullableDecl Object o) {
         int mask = hashTableMask();
         int index =
             CompactHashing.remove(
-                entry.getKey(), entry.getValue(), mask, table, entries, keys, values);
+                entry.getKey(),
+                entry.getValue(),
+                mask,
+                requireTable(),
+                requireEntries(),
+                requireKeys(),
+                requireValues());
         if (index == -1) {
           return false;
         }
@@ -723,7 +803,7 @@ public boolean remove(@NullableDecl Object o) {
   }
 
   Iterator<Entry<K, V>> entrySetIterator() {
-    @NullableDecl Map<K, V> delegate = delegateOrNull();
+    Map<K, V> delegate = delegateOrNull();
     if (delegate != null) {
       return delegate.entrySet().iterator();
     }
@@ -736,18 +816,17 @@ Entry<K, V> getOutput(int entry) {
   }
 
   final class MapEntry extends AbstractMapEntry<K, V> {
-    @NullableDecl private final K key;
+    @ParametricNullness private final K key;
 
     private int lastKnownIndex;
 
-    @SuppressWarnings("unchecked") // known to be a K
     MapEntry(int index) {
-      this.key = (K) keys[index];
+      this.key = key(index);
       this.lastKnownIndex = index;
     }
 
-    @NullableDecl
     @Override
+    @ParametricNullness
     public K getKey() {
       return key;
     }
@@ -755,37 +834,48 @@ public K getKey() {
     private void updateLastKnownIndex() {
       if (lastKnownIndex == -1
           || lastKnownIndex >= size()
-          || !Objects.equal(key, keys[lastKnownIndex])) {
+          || !Objects.equal(key, key(lastKnownIndex))) {
         lastKnownIndex = indexOf(key);
       }
     }
 
-    @SuppressWarnings("unchecked") // known to be a V
     @Override
-    @NullableDecl
+    @ParametricNullness
     public V getValue() {
-      @NullableDecl Map<K, V> delegate = delegateOrNull();
+      Map<K, V> delegate = delegateOrNull();
       if (delegate != null) {
-        return delegate.get(key);
+        /*
+         * The cast is safe because the entry is present in the map. Or, if it has been removed by a
+         * concurrent modification, behavior is undefined.
+         */
+        return uncheckedCastNullableTToT(delegate.get(key));
       }
       updateLastKnownIndex();
-      return (lastKnownIndex == -1) ? null : (V) values[lastKnownIndex];
+      /*
+       * If the entry has been removed from the map, we return null, even though that might not be a
+       * valid value. That's the best we can do, short of holding a reference to the most recently
+       * seen value. And while we *could* do that, we aren't required to: Map.Entry explicitly says
+       * that behavior is undefined when the backing map is modified through another API. (It even
+       * permits us to throw IllegalStateException. Maybe we should have done that, but we probably
+       * shouldn't change now for fear of breaking people.)
+       */
+      return (lastKnownIndex == -1) ? unsafeNull() : value(lastKnownIndex);
     }
 
-    @SuppressWarnings("unchecked") // known to be a V
     @Override
-    public V setValue(V value) {
-      @NullableDecl Map<K, V> delegate = delegateOrNull();
+    @ParametricNullness
+    public V setValue(@ParametricNullness V value) {
+      Map<K, V> delegate = delegateOrNull();
       if (delegate != null) {
-        return delegate.put(key, value);
+        return uncheckedCastNullableTToT(delegate.put(key, value)); // See discussion in getValue().
       }
       updateLastKnownIndex();
       if (lastKnownIndex == -1) {
         put(key, value);
-        return null;
+        return unsafeNull(); // See discussion in getValue().
       } else {
-        V old = (V) values[lastKnownIndex];
-        values[lastKnownIndex] = value;
+        V old = value(lastKnownIndex);
+        CompactHashMap.this.setValue(lastKnownIndex, value);
         return old;
       }
     }
@@ -793,7 +883,7 @@ public V setValue(V value) {
 
   @Override
   public int size() {
-    @NullableDecl Map<K, V> delegate = delegateOrNull();
+    Map<K, V> delegate = delegateOrNull();
     return (delegate != null) ? delegate.size() : size;
   }
 
@@ -803,20 +893,20 @@ public boolean isEmpty() {
   }
 
   @Override
-  public boolean containsValue(@NullableDecl Object value) {
-    @NullableDecl Map<K, V> delegate = delegateOrNull();
+  public boolean containsValue(@CheckForNull Object value) {
+    Map<K, V> delegate = delegateOrNull();
     if (delegate != null) {
       return delegate.containsValue(value);
     }
     for (int i = 0; i < size; i++) {
-      if (Objects.equal(value, values[i])) {
+      if (Objects.equal(value, value(i))) {
         return true;
       }
     }
     return false;
   }
 
-  @NullableDecl private transient Collection<V> valuesView;
+  @CheckForNull private transient Collection<V> valuesView;
 
   @Override
   public Collection<V> values() {
@@ -846,15 +936,15 @@ public Iterator<V> iterator() {
   }
 
   Iterator<V> valuesIterator() {
-    @NullableDecl Map<K, V> delegate = delegateOrNull();
+    Map<K, V> delegate = delegateOrNull();
     if (delegate != null) {
       return delegate.values().iterator();
     }
     return new Itr<V>() {
-      @SuppressWarnings("unchecked") // known to be a V
       @Override
+      @ParametricNullness
       V getOutput(int entry) {
-        return (V) values[entry];
+        return value(entry);
       }
     };
   }
@@ -867,7 +957,7 @@ public void trimToSize() {
     if (needsAllocArrays()) {
       return;
     }
-    @NullableDecl Map<K, V> delegate = delegateOrNull();
+    Map<K, V> delegate = delegateOrNull();
     if (delegate != null) {
       Map<K, V> newDelegate = createHashFloodingResistantDelegate(size());
       newDelegate.putAll(delegate);
@@ -875,7 +965,7 @@ public void trimToSize() {
       return;
     }
     int size = this.size;
-    if (size < entries.length) {
+    if (size < requireEntries().length) {
       resizeEntries(size);
     }
     int minimumTableSize = CompactHashing.tableSize(size);
@@ -891,7 +981,7 @@ public void clear() {
       return;
     }
     incrementModCount();
-    @NullableDecl Map<K, V> delegate = delegateOrNull();
+    Map<K, V> delegate = delegateOrNull();
     if (delegate != null) {
       metadata =
           Ints.constrainToRange(size(), CompactHashing.DEFAULT_SIZE, CompactHashing.MAX_SIZE);
@@ -899,10 +989,10 @@ public void clear() {
       table = null;
       size = 0;
     } else {
-      Arrays.fill(keys, 0, size, null);
-      Arrays.fill(values, 0, size, null);
-      CompactHashing.tableClear(table);
-      Arrays.fill(entries, 0, size, 0);
+      Arrays.fill(requireKeys(), 0, size, null);
+      Arrays.fill(requireValues(), 0, size, null);
+      CompactHashing.tableClear(requireTable());
+      Arrays.fill(requireEntries(), 0, size, 0);
       this.size = 0;
     }
   }
@@ -932,4 +1022,66 @@ private void readObject(ObjectInputStream stream) throws IOException, ClassNotFo
       put(key, value);
     }
   }
+
+  /*
+   * The following methods are safe to call as long as both of the following hold:
+   *
+   * - allocArrays() has been called. Callers can confirm this by checking needsAllocArrays().
+   *
+   * - The map has not switched to delegating to a java.util implementation to mitigate hash
+   *   flooding. Callers can confirm this by null-checking delegateOrNull().
+   *
+   * In an ideal world, we would document why we know those things are true every time we call these
+   * methods. But that is a bit too painful....
+   */
+
+  private Object requireTable() {
+    return requireNonNull(table);
+  }
+
+  private int[] requireEntries() {
+    return requireNonNull(entries);
+  }
+
+  private @Nullable Object[] requireKeys() {
+    return requireNonNull(keys);
+  }
+
+  private @Nullable Object[] requireValues() {
+    return requireNonNull(values);
+  }
+
+  /*
+   * The following methods are safe to call as long as the conditions in the *previous* comment are
+   * met *and* the index is less than size().
+   *
+   * (The above explains when these methods are safe from a `nullness` perspective. From an
+   * `unchecked` perspective, they're safe because we put only K/V elements into each array.)
+   */
+
+  @SuppressWarnings("unchecked")
+  private K key(int i) {
+    return (K) requireKeys()[i];
+  }
+
+  @SuppressWarnings("unchecked")
+  private V value(int i) {
+    return (V) requireValues()[i];
+  }
+
+  private int entry(int i) {
+    return requireEntries()[i];
+  }
+
+  private void setKey(int i, K key) {
+    requireKeys()[i] = key;
+  }
+
+  private void setValue(int i, V value) {
+    requireValues()[i] = value;
+  }
+
+  private void setEntry(int i, int value) {
+    requireEntries()[i] = value;
+  }
 }
diff --git a/android/guava/src/com/google/common/collect/CompactHashSet.java b/android/guava/src/com/google/common/collect/CompactHashSet.java
index d4c585cf5140..08c729423fe4 100644
--- a/android/guava/src/com/google/common/collect/CompactHashSet.java
+++ b/android/guava/src/com/google/common/collect/CompactHashSet.java
@@ -19,6 +19,7 @@
 import static com.google.common.collect.CollectPreconditions.checkRemove;
 import static com.google.common.collect.CompactHashing.UNSET;
 import static com.google.common.collect.Hashing.smearedHash;
+import static java.util.Objects.requireNonNull;
 
 import com.google.common.annotations.GwtIncompatible;
 import com.google.common.annotations.VisibleForTesting;
@@ -40,7 +41,8 @@
 import java.util.LinkedHashSet;
 import java.util.NoSuchElementException;
 import java.util.Set;
-import org.checkerframework.checker.nullness.compatqual.NullableDecl;
+import javax.annotation.CheckForNull;
+import org.checkerframework.checker.nullness.qual.Nullable;
 
 /**
  * CompactHashSet is an implementation of a Set. All optional operations (adding and removing) are
@@ -70,11 +72,12 @@
  * @author Jon Noack
  */
 @GwtIncompatible // not worth using in GWT for now
-class CompactHashSet<E> extends AbstractSet<E> implements Serializable {
+@ElementTypesAreNonnullByDefault
+class CompactHashSet<E extends @Nullable Object> extends AbstractSet<E> implements Serializable {
   // TODO(user): cache all field accesses in local vars
 
   /** Creates an empty {@code CompactHashSet} instance. */
-  public static <E> CompactHashSet<E> create() {
+  public static <E extends @Nullable Object> CompactHashSet<E> create() {
     return new CompactHashSet<>();
   }
 
@@ -85,7 +88,8 @@ public static <E> CompactHashSet<E> create() {
    * @param collection the elements that the set should contain
    * @return a new {@code CompactHashSet} containing those elements (minus duplicates)
    */
-  public static <E> CompactHashSet<E> create(Collection<? extends E> collection) {
+  public static <E extends @Nullable Object> CompactHashSet<E> create(
+      Collection<? extends E> collection) {
     CompactHashSet<E> set = createWithExpectedSize(collection.size());
     set.addAll(collection);
     return set;
@@ -99,7 +103,7 @@ public static <E> CompactHashSet<E> create(Collection<? extends E> collection) {
    * @return a new {@code CompactHashSet} containing those elements (minus duplicates)
    */
   @SafeVarargs
-  public static <E> CompactHashSet<E> create(E... elements) {
+  public static <E extends @Nullable Object> CompactHashSet<E> create(E... elements) {
     CompactHashSet<E> set = createWithExpectedSize(elements.length);
     Collections.addAll(set, elements);
     return set;
@@ -114,7 +118,8 @@ public static <E> CompactHashSet<E> create(E... elements) {
    *     elements without resizing
    * @throws IllegalArgumentException if {@code expectedSize} is negative
    */
-  public static <E> CompactHashSet<E> createWithExpectedSize(int expectedSize) {
+  public static <E extends @Nullable Object> CompactHashSet<E> createWithExpectedSize(
+      int expectedSize) {
     return new CompactHashSet<>(expectedSize);
   }
 
@@ -132,6 +137,10 @@ public static <E> CompactHashSet<E> createWithExpectedSize(int expectedSize) {
    */
   private static final int MAX_HASH_BUCKET_LENGTH = 9;
 
+  // See CompactHashMap for a detailed description of how the following fields work. That
+  // description talks about `keys`, `values`, and `entries`; here the `keys` and `values` arrays
+  // are replaced by a single `elements` array but everything else works similarly.
+
   /**
    * The hashtable object. This can be either:
    *
@@ -151,7 +160,7 @@ public static <E> CompactHashSet<E> createWithExpectedSize(int expectedSize) {
    *   <li>null, if no entries have yet been added to the map
    * </ul>
    */
-  @NullableDecl private transient Object table;
+  @CheckForNull private transient Object table;
 
   /**
    * Contains the logical entries, in the range of [0, size()). The high bits of each int are the
@@ -161,20 +170,20 @@ public static <E> CompactHashSet<E> createWithExpectedSize(int expectedSize) {
    *
    * <pre>
    * hash  = aaaaaaaa
-   * mask  = 0000ffff
-   * next  = 0000bbbb
-   * entry = aaaabbbb
+   * mask  = 00000fff
+   * next  = 00000bbb
+   * entry = aaaaabbb
    * </pre>
    *
    * <p>The pointers in [size(), entries.length) are all "null" (UNSET).
    */
-  @NullableDecl private transient int[] entries;
+  @CheckForNull private transient int[] entries;
 
   /**
    * The elements contained in the set, in the range of [0, size()). The elements in [size(),
    * elements.length) are all {@code null}.
    */
-  @VisibleForTesting @NullableDecl transient Object[] elements;
+  @VisibleForTesting @CheckForNull transient @Nullable Object[] elements;
 
   /**
    * Keeps track of metadata like the number of hash table bits and modifications of this data
@@ -233,7 +242,7 @@ int allocArrays() {
 
   @SuppressWarnings("unchecked")
   @VisibleForTesting
-  @NullableDecl
+  @CheckForNull
   Set<E> delegateOrNull() {
     if (table instanceof Set) {
       return (Set<E>) table;
@@ -245,13 +254,12 @@ private Set<E> createHashFloodingResistantDelegate(int tableSize) {
     return new LinkedHashSet<>(tableSize, 1.0f);
   }
 
-  @SuppressWarnings("unchecked")
   @VisibleForTesting
   @CanIgnoreReturnValue
   Set<E> convertToHashFloodingResistantImplementation() {
     Set<E> newDelegate = createHashFloodingResistantDelegate(hashTableMask() + 1);
     for (int i = firstEntryIndex(); i >= 0; i = getSuccessor(i)) {
-      newDelegate.add((E) elements[i]);
+      newDelegate.add(element(i));
     }
     this.table = newDelegate;
     this.entries = null;
@@ -283,29 +291,29 @@ void incrementModCount() {
 
   @CanIgnoreReturnValue
   @Override
-  public boolean add(@NullableDecl E object) {
+  public boolean add(@ParametricNullness E object) {
     if (needsAllocArrays()) {
       allocArrays();
     }
-    @NullableDecl Set<E> delegate = delegateOrNull();
+    Set<E> delegate = delegateOrNull();
     if (delegate != null) {
       return delegate.add(object);
     }
-    int[] entries = this.entries;
-    Object[] elements = this.elements;
+    int[] entries = requireEntries();
+    @Nullable Object[] elements = requireElements();
 
     int newEntryIndex = this.size; // current size, and pointer to the entry to be appended
     int newSize = newEntryIndex + 1;
     int hash = smearedHash(object);
     int mask = hashTableMask();
     int tableIndex = hash & mask;
-    int next = CompactHashing.tableGet(table, tableIndex);
+    int next = CompactHashing.tableGet(requireTable(), tableIndex);
     if (next == UNSET) { // uninitialized bucket
       if (newSize > mask) {
         // Resize and add new entry
         mask = resizeTable(mask, CompactHashing.newCapacity(mask), hash, newEntryIndex);
       } else {
-        CompactHashing.tableSet(table, tableIndex, newEntryIndex + 1);
+        CompactHashing.tableSet(requireTable(), tableIndex, newEntryIndex + 1);
       }
     } else {
       int entryIndex;
@@ -344,14 +352,14 @@ public boolean add(@NullableDecl E object) {
   /**
    * Creates a fresh entry with the specified object at the specified position in the entry arrays.
    */
-  void insertEntry(int entryIndex, @NullableDecl E object, int hash, int mask) {
-    this.entries[entryIndex] = CompactHashing.maskCombine(hash, UNSET, mask);
-    this.elements[entryIndex] = object;
+  void insertEntry(int entryIndex, @ParametricNullness E object, int hash, int mask) {
+    setEntry(entryIndex, CompactHashing.maskCombine(hash, UNSET, mask));
+    setElement(entryIndex, object);
   }
 
   /** Resizes the entries storage if necessary. */
   private void resizeMeMaybe(int newSize) {
-    int entriesSize = entries.length;
+    int entriesSize = requireEntries().length;
     if (newSize > entriesSize) {
       // 1.5x but round up to nearest odd (this is optimal for memory consumption on Android)
       int newCapacity =
@@ -367,12 +375,12 @@ private void resizeMeMaybe(int newSize) {
    * the current capacity.
    */
   void resizeEntries(int newCapacity) {
-    this.entries = Arrays.copyOf(entries, newCapacity);
-    this.elements = Arrays.copyOf(elements, newCapacity);
+    this.entries = Arrays.copyOf(requireEntries(), newCapacity);
+    this.elements = Arrays.copyOf(requireElements(), newCapacity);
   }
 
   @CanIgnoreReturnValue
-  private int resizeTable(int mask, int newCapacity, int targetHash, int targetEntryIndex) {
+  private int resizeTable(int oldMask, int newCapacity, int targetHash, int targetEntryIndex) {
     Object newTable = CompactHashing.createTable(newCapacity);
     int newMask = newCapacity - 1;
 
@@ -381,25 +389,25 @@ private int resizeTable(int mask, int newCapacity, int targetHash, int targetEnt
       CompactHashing.tableSet(newTable, targetHash & newMask, targetEntryIndex + 1);
     }
 
-    Object table = this.table;
-    int[] entries = this.entries;
+    Object oldTable = requireTable();
+    int[] entries = requireEntries();
 
     // Loop over current hashtable
-    for (int tableIndex = 0; tableIndex <= mask; tableIndex++) {
-      int next = CompactHashing.tableGet(table, tableIndex);
-      while (next != UNSET) {
-        int entryIndex = next - 1;
-        int entry = entries[entryIndex];
+    for (int oldTableIndex = 0; oldTableIndex <= oldMask; oldTableIndex++) {
+      int oldNext = CompactHashing.tableGet(oldTable, oldTableIndex);
+      while (oldNext != UNSET) {
+        int entryIndex = oldNext - 1;
+        int oldEntry = entries[entryIndex];
 
         // Rebuild hash using entry hashPrefix and tableIndex ("hashSuffix")
-        int hash = CompactHashing.getHashPrefix(entry, mask) | tableIndex;
+        int hash = CompactHashing.getHashPrefix(oldEntry, oldMask) | oldTableIndex;
 
         int newTableIndex = hash & newMask;
         int newNext = CompactHashing.tableGet(newTable, newTableIndex);
-        CompactHashing.tableSet(newTable, newTableIndex, next);
+        CompactHashing.tableSet(newTable, newTableIndex, oldNext);
         entries[entryIndex] = CompactHashing.maskCombine(hash, newNext, newMask);
 
-        next = CompactHashing.getNext(entry, mask);
+        oldNext = CompactHashing.getNext(oldEntry, oldMask);
       }
     }
 
@@ -409,26 +417,26 @@ private int resizeTable(int mask, int newCapacity, int targetHash, int targetEnt
   }
 
   @Override
-  public boolean contains(@NullableDecl Object object) {
+  public boolean contains(@CheckForNull Object object) {
     if (needsAllocArrays()) {
       return false;
     }
-    @NullableDecl Set<E> delegate = delegateOrNull();
+    Set<E> delegate = delegateOrNull();
     if (delegate != null) {
       return delegate.contains(object);
     }
     int hash = smearedHash(object);
     int mask = hashTableMask();
-    int next = CompactHashing.tableGet(table, hash & mask);
+    int next = CompactHashing.tableGet(requireTable(), hash & mask);
     if (next == UNSET) {
       return false;
     }
     int hashPrefix = CompactHashing.getHashPrefix(hash, mask);
     do {
       int entryIndex = next - 1;
-      int entry = entries[entryIndex];
+      int entry = entry(entryIndex);
       if (CompactHashing.getHashPrefix(entry, mask) == hashPrefix
-          && Objects.equal(object, elements[entryIndex])) {
+          && Objects.equal(object, element(entryIndex))) {
         return true;
       }
       next = CompactHashing.getNext(entry, mask);
@@ -438,18 +446,24 @@ public boolean contains(@NullableDecl Object object) {
 
   @CanIgnoreReturnValue
   @Override
-  public boolean remove(@NullableDecl Object object) {
+  public boolean remove(@CheckForNull Object object) {
     if (needsAllocArrays()) {
       return false;
     }
-    @NullableDecl Set<E> delegate = delegateOrNull();
+    Set<E> delegate = delegateOrNull();
     if (delegate != null) {
       return delegate.remove(object);
     }
     int mask = hashTableMask();
     int index =
         CompactHashing.remove(
-            object, /* value= */ null, mask, table, entries, elements, /* values= */ null);
+            object,
+            /* value= */ null,
+            mask,
+            requireTable(),
+            requireEntries(),
+            requireElements(),
+            /* values= */ null);
     if (index == -1) {
       return false;
     }
@@ -465,10 +479,13 @@ public boolean remove(@NullableDecl Object object) {
    * Moves the last entry in the entry array into {@code dstIndex}, and nulls out its old position.
    */
   void moveLastEntry(int dstIndex, int mask) {
+    Object table = requireTable();
+    int[] entries = requireEntries();
+    @Nullable Object[] elements = requireElements();
     int srcIndex = size() - 1;
     if (dstIndex < srcIndex) {
       // move last entry to deleted spot
-      @NullableDecl Object object = elements[srcIndex];
+      Object object = elements[srcIndex];
       elements[dstIndex] = object;
       elements[srcIndex] = null;
 
@@ -520,7 +537,7 @@ int adjustAfterRemove(int indexBeforeRemove, @SuppressWarnings("unused") int ind
 
   @Override
   public Iterator<E> iterator() {
-    @NullableDecl Set<E> delegate = delegateOrNull();
+    Set<E> delegate = delegateOrNull();
     if (delegate != null) {
       return delegate.iterator();
     }
@@ -534,15 +551,15 @@ public boolean hasNext() {
         return currentIndex >= 0;
       }
 
-      @SuppressWarnings("unchecked") // known to be Es
       @Override
+      @ParametricNullness
       public E next() {
         checkForConcurrentModification();
         if (!hasNext()) {
           throw new NoSuchElementException();
         }
         indexToRemove = currentIndex;
-        E result = (E) elements[currentIndex];
+        E result = element(currentIndex);
         currentIndex = getSuccessor(currentIndex);
         return result;
       }
@@ -552,7 +569,7 @@ public void remove() {
         checkForConcurrentModification();
         checkRemove(indexToRemove >= 0);
         incrementExpectedModCount();
-        CompactHashSet.this.remove(elements[indexToRemove]);
+        CompactHashSet.this.remove(element(indexToRemove));
         currentIndex = adjustAfterRemove(currentIndex, indexToRemove);
         indexToRemove = -1;
       }
@@ -571,7 +588,7 @@ private void checkForConcurrentModification() {
 
   @Override
   public int size() {
-    @NullableDecl Set<E> delegate = delegateOrNull();
+    Set<E> delegate = delegateOrNull();
     return (delegate != null) ? delegate.size() : size;
   }
 
@@ -581,27 +598,28 @@ public boolean isEmpty() {
   }
 
   @Override
-  public Object[] toArray() {
+  public @Nullable Object[] toArray() {
     if (needsAllocArrays()) {
       return new Object[0];
     }
-    @NullableDecl Set<E> delegate = delegateOrNull();
-    return (delegate != null) ? delegate.toArray() : Arrays.copyOf(elements, size);
+    Set<E> delegate = delegateOrNull();
+    return (delegate != null) ? delegate.toArray() : Arrays.copyOf(requireElements(), size);
   }
 
   @CanIgnoreReturnValue
   @Override
-  public <T> T[] toArray(T[] a) {
+  @SuppressWarnings("nullness") // b/192354773 in our checker affects toArray declarations
+  public <T extends @Nullable Object> T[] toArray(T[] a) {
     if (needsAllocArrays()) {
       if (a.length > 0) {
         a[0] = null;
       }
       return a;
     }
-    @NullableDecl Set<E> delegate = delegateOrNull();
+    Set<E> delegate = delegateOrNull();
     return (delegate != null)
         ? delegate.toArray(a)
-        : ObjectArrays.toArrayImpl(elements, 0, size, a);
+        : ObjectArrays.toArrayImpl(requireElements(), 0, size, a);
   }
 
   /**
@@ -612,7 +630,7 @@ public void trimToSize() {
     if (needsAllocArrays()) {
       return;
     }
-    @NullableDecl Set<E> delegate = delegateOrNull();
+    Set<E> delegate = delegateOrNull();
     if (delegate != null) {
       Set<E> newDelegate = createHashFloodingResistantDelegate(size());
       newDelegate.addAll(delegate);
@@ -620,7 +638,7 @@ public void trimToSize() {
       return;
     }
     int size = this.size;
-    if (size < entries.length) {
+    if (size < requireEntries().length) {
       resizeEntries(size);
     }
     int minimumTableSize = CompactHashing.tableSize(size);
@@ -636,7 +654,7 @@ public void clear() {
       return;
     }
     incrementModCount();
-    @NullableDecl Set<E> delegate = delegateOrNull();
+    Set<E> delegate = delegateOrNull();
     if (delegate != null) {
       metadata =
           Ints.constrainToRange(size(), CompactHashing.DEFAULT_SIZE, CompactHashing.MAX_SIZE);
@@ -644,9 +662,9 @@ public void clear() {
       table = null;
       size = 0;
     } else {
-      Arrays.fill(elements, 0, size, null);
-      CompactHashing.tableClear(table);
-      Arrays.fill(entries, 0, size, 0);
+      Arrays.fill(requireElements(), 0, size, null);
+      CompactHashing.tableClear(requireTable());
+      Arrays.fill(requireEntries(), 0, size, 0);
       this.size = 0;
     }
   }
@@ -672,4 +690,38 @@ private void readObject(ObjectInputStream stream) throws IOException, ClassNotFo
       add(element);
     }
   }
+
+  /*
+   * For discussion of the safety of the following methods, see the comments near the end of
+   * CompactHashMap.
+   */
+
+  private Object requireTable() {
+    return requireNonNull(table);
+  }
+
+  private int[] requireEntries() {
+    return requireNonNull(entries);
+  }
+
+  private @Nullable Object[] requireElements() {
+    return requireNonNull(elements);
+  }
+
+  @SuppressWarnings("unchecked")
+  private E element(int i) {
+    return (E) requireElements()[i];
+  }
+
+  private int entry(int i) {
+    return requireEntries()[i];
+  }
+
+  private void setElement(int i, E value) {
+    requireElements()[i] = value;
+  }
+
+  private void setEntry(int i, int value) {
+    requireEntries()[i] = value;
+  }
 }
diff --git a/android/guava/src/com/google/common/collect/CompactHashing.java b/android/guava/src/com/google/common/collect/CompactHashing.java
index 7e83a05faa41..a8fe90214c78 100644
--- a/android/guava/src/com/google/common/collect/CompactHashing.java
+++ b/android/guava/src/com/google/common/collect/CompactHashing.java
@@ -20,7 +20,8 @@
 import com.google.common.base.Objects;
 import com.google.common.primitives.Ints;
 import java.util.Arrays;
-import org.checkerframework.checker.nullness.compatqual.NullableDecl;
+import javax.annotation.CheckForNull;
+import org.checkerframework.checker.nullness.qual.Nullable;
 
 /**
  * Helper classes and static methods for implementing compact hash-based collections.
@@ -28,6 +29,7 @@
  * @author Jon Noack
  */
 @GwtIncompatible
+@ElementTypesAreNonnullByDefault
 final class CompactHashing {
   private CompactHashing() {}
 
@@ -96,6 +98,11 @@ static void tableClear(Object table) {
     }
   }
 
+  /**
+   * Returns {@code table[index]}, where {@code table} is actually a {@code byte[]}, {@code
+   * short[]}, or {@code int[]}. When it is a {@code byte[]} or {@code short[]}, the returned value
+   * is unsigned, so the range of possible returned values is 0–255 or 0–65535, respectively.
+   */
   static int tableGet(Object table, int index) {
     if (table instanceof byte[]) {
       return ((byte[]) table)[index] & BYTE_MASK; // unsigned read
@@ -106,6 +113,13 @@ static int tableGet(Object table, int index) {
     }
   }
 
+  /**
+   * Sets {@code table[index]} to {@code entry}, where {@code table} is actually a {@code byte[]},
+   * {@code short[]}, or {@code int[]}. The value of {@code entry} should fit in the size of the
+   * assigned array element, when seen as an unsigned value. So if {@code table} is a {@code byte[]}
+   * then we should have {@code 0 ≤ entry ≤ 255}, and if {@code table} is a {@code short[]} then we
+   * should have {@code 0 ≤ entry ≤ 65535}. It is the caller's responsibility to ensure this.
+   */
   static void tableSet(Object table, int index, int entry) {
     if (table instanceof byte[]) {
       ((byte[]) table)[index] = (byte) entry; // unsigned write
@@ -143,13 +157,13 @@ static int maskCombine(int prefix, int suffix, int mask) {
   }
 
   static int remove(
-      @NullableDecl Object key,
-      @NullableDecl Object value,
+      @CheckForNull Object key,
+      @CheckForNull Object value,
       int mask,
       Object table,
       int[] entries,
-      Object[] keys,
-      @NullableDecl Object[] values) {
+      @Nullable Object[] keys,
+      @CheckForNull @Nullable Object[] values) {
     int hash = Hashing.smearedHash(key);
     int tableIndex = hash & mask;
     int next = tableGet(table, tableIndex);
diff --git a/android/guava/src/com/google/common/collect/CompactLinkedHashMap.java b/android/guava/src/com/google/common/collect/CompactLinkedHashMap.java
index 9135524677b3..fb648a7a4f1b 100644
--- a/android/guava/src/com/google/common/collect/CompactLinkedHashMap.java
+++ b/android/guava/src/com/google/common/collect/CompactLinkedHashMap.java
@@ -16,13 +16,16 @@
 
 package com.google.common.collect;
 
+import static java.util.Objects.requireNonNull;
+
 import com.google.common.annotations.GwtIncompatible;
 import com.google.common.annotations.VisibleForTesting;
 import com.google.errorprone.annotations.CanIgnoreReturnValue;
 import java.util.Arrays;
 import java.util.LinkedHashMap;
 import java.util.Map;
-import org.checkerframework.checker.nullness.compatqual.NullableDecl;
+import javax.annotation.CheckForNull;
+import org.checkerframework.checker.nullness.qual.Nullable;
 
 /**
  * CompactLinkedHashMap is an implementation of a Map with insertion or LRU iteration order,
@@ -45,11 +48,14 @@
  * @author Louis Wasserman
  */
 @GwtIncompatible // not worth using in GWT for now
-class CompactLinkedHashMap<K, V> extends CompactHashMap<K, V> {
+@ElementTypesAreNonnullByDefault
+class CompactLinkedHashMap<K extends @Nullable Object, V extends @Nullable Object>
+    extends CompactHashMap<K, V> {
   // TODO(lowasser): implement removeEldestEntry so this can be used as a drop-in replacement
 
   /** Creates an empty {@code CompactLinkedHashMap} instance. */
-  public static <K, V> CompactLinkedHashMap<K, V> create() {
+  public static <K extends @Nullable Object, V extends @Nullable Object>
+      CompactLinkedHashMap<K, V> create() {
     return new CompactLinkedHashMap<>();
   }
 
@@ -62,7 +68,8 @@ public static <K, V> CompactLinkedHashMap<K, V> create() {
    *     expectedSize} elements without resizing
    * @throws IllegalArgumentException if {@code expectedSize} is negative
    */
-  public static <K, V> CompactLinkedHashMap<K, V> createWithExpectedSize(int expectedSize) {
+  public static <K extends @Nullable Object, V extends @Nullable Object>
+      CompactLinkedHashMap<K, V> createWithExpectedSize(int expectedSize) {
     return new CompactLinkedHashMap<>(expectedSize);
   }
 
@@ -77,7 +84,7 @@ public static <K, V> CompactLinkedHashMap<K, V> createWithExpectedSize(int expec
    * <p>A node with "prev" pointer equal to {@code ENDPOINT} is the first node in the linked list,
    * and a node with "next" pointer equal to {@code ENDPOINT} is the last node.
    */
-  @VisibleForTesting @NullableDecl transient long[] links;
+  @CheckForNull @VisibleForTesting transient long[] links;
 
   /** Pointer to the first node in the linked list, or {@code ENDPOINT} if there are no entries. */
   private transient int firstEntry;
@@ -127,23 +134,29 @@ Map<K, V> convertToHashFloodingResistantImplementation() {
     return result;
   }
 
+  /*
+   * For discussion of the safety of the following methods for operating on predecessors and
+   * successors, see the comments near the end of CompactHashMap, noting that the methods here call
+   * link(), which is defined at the end of this file.
+   */
+
   private int getPredecessor(int entry) {
-    return ((int) (links[entry] >>> 32)) - 1;
+    return ((int) (link(entry) >>> 32)) - 1;
   }
 
   @Override
   int getSuccessor(int entry) {
-    return ((int) links[entry]) - 1;
+    return ((int) link(entry)) - 1;
   }
 
   private void setSuccessor(int entry, int succ) {
     long succMask = (~0L) >>> 32;
-    links[entry] = (links[entry] & ~succMask) | ((succ + 1) & succMask);
+    setLink(entry, (link(entry) & ~succMask) | ((succ + 1) & succMask));
   }
 
   private void setPredecessor(int entry, int pred) {
     long predMask = ~0L << 32;
-    links[entry] = (links[entry] & ~predMask) | ((long) (pred + 1) << 32);
+    setLink(entry, (link(entry) & ~predMask) | ((long) (pred + 1) << 32));
   }
 
   private void setSucceeds(int pred, int succ) {
@@ -161,7 +174,8 @@ private void setSucceeds(int pred, int succ) {
   }
 
   @Override
-  void insertEntry(int entryIndex, @NullableDecl K key, @NullableDecl V value, int hash, int mask) {
+  void insertEntry(
+      int entryIndex, @ParametricNullness K key, @ParametricNullness V value, int hash, int mask) {
     super.insertEntry(entryIndex, key, value, hash, mask);
     setSucceeds(lastEntry, entryIndex);
     setSucceeds(entryIndex, ENDPOINT);
@@ -189,13 +203,13 @@ void moveLastEntry(int dstIndex, int mask) {
       setSucceeds(getPredecessor(srcIndex), dstIndex);
       setSucceeds(dstIndex, getSuccessor(srcIndex));
     }
-    links[srcIndex] = 0;
+    setLink(srcIndex, 0);
   }
 
   @Override
   void resizeEntries(int newCapacity) {
     super.resizeEntries(newCapacity);
-    links = Arrays.copyOf(links, newCapacity);
+    links = Arrays.copyOf(requireLinks(), newCapacity);
   }
 
   @Override
@@ -220,4 +234,27 @@ public void clear() {
     }
     super.clear();
   }
+
+  /*
+   * For discussion of the safety of the following methods, see the comments near the end of
+   * CompactHashMap.
+   */
+
+  private long[] requireLinks() {
+    return requireNonNull(links);
+  }
+
+  private long link(int i) {
+    return requireLinks()[i];
+  }
+
+  private void setLink(int i, long value) {
+    requireLinks()[i] = value;
+  }
+
+  /*
+   * We don't define getPredecessor+getSuccessor and setPredecessor+setSuccessor here because
+   * they're defined above -- including logic to add and subtract 1 to map between the values stored
+   * in the predecessor/successor arrays and the indexes in the elements array that they identify.
+   */
 }
diff --git a/android/guava/src/com/google/common/collect/CompactLinkedHashSet.java b/android/guava/src/com/google/common/collect/CompactLinkedHashSet.java
index 4f9aa4a0c137..21d48058ad72 100644
--- a/android/guava/src/com/google/common/collect/CompactLinkedHashSet.java
+++ b/android/guava/src/com/google/common/collect/CompactLinkedHashSet.java
@@ -16,13 +16,16 @@
 
 package com.google.common.collect;
 
+import static java.util.Objects.requireNonNull;
+
 import com.google.common.annotations.GwtIncompatible;
 import com.google.errorprone.annotations.CanIgnoreReturnValue;
 import java.util.Arrays;
 import java.util.Collection;
 import java.util.Collections;
 import java.util.Set;
-import org.checkerframework.checker.nullness.compatqual.NullableDecl;
+import javax.annotation.CheckForNull;
+import org.checkerframework.checker.nullness.qual.Nullable;
 
 /**
  * CompactLinkedHashSet is an implementation of a Set, which a predictable iteration order that
@@ -46,10 +49,11 @@
  * @author Louis Wasserman
  */
 @GwtIncompatible // not worth using in GWT for now
-class CompactLinkedHashSet<E> extends CompactHashSet<E> {
+@ElementTypesAreNonnullByDefault
+class CompactLinkedHashSet<E extends @Nullable Object> extends CompactHashSet<E> {
 
   /** Creates an empty {@code CompactLinkedHashSet} instance. */
-  public static <E> CompactLinkedHashSet<E> create() {
+  public static <E extends @Nullable Object> CompactLinkedHashSet<E> create() {
     return new CompactLinkedHashSet<>();
   }
 
@@ -60,7 +64,8 @@ public static <E> CompactLinkedHashSet<E> create() {
    * @param collection the elements that the set should contain
    * @return a new {@code CompactLinkedHashSet} containing those elements (minus duplicates)
    */
-  public static <E> CompactLinkedHashSet<E> create(Collection<? extends E> collection) {
+  public static <E extends @Nullable Object> CompactLinkedHashSet<E> create(
+      Collection<? extends E> collection) {
     CompactLinkedHashSet<E> set = createWithExpectedSize(collection.size());
     set.addAll(collection);
     return set;
@@ -74,7 +79,7 @@ public static <E> CompactLinkedHashSet<E> create(Collection<? extends E> collect
    * @return a new {@code CompactLinkedHashSet} containing those elements (minus duplicates)
    */
   @SafeVarargs
-  public static <E> CompactLinkedHashSet<E> create(E... elements) {
+  public static <E extends @Nullable Object> CompactLinkedHashSet<E> create(E... elements) {
     CompactLinkedHashSet<E> set = createWithExpectedSize(elements.length);
     Collections.addAll(set, elements);
     return set;
@@ -89,7 +94,8 @@ public static <E> CompactLinkedHashSet<E> create(E... elements) {
    *     expectedSize} elements without resizing
    * @throws IllegalArgumentException if {@code expectedSize} is negative
    */
-  public static <E> CompactLinkedHashSet<E> createWithExpectedSize(int expectedSize) {
+  public static <E extends @Nullable Object> CompactLinkedHashSet<E> createWithExpectedSize(
+      int expectedSize) {
     return new CompactLinkedHashSet<>(expectedSize);
   }
 
@@ -103,13 +109,13 @@ public static <E> CompactLinkedHashSet<E> createWithExpectedSize(int expectedSiz
    * Pointer to the predecessor of an entry in insertion order. ENDPOINT indicates a node is the
    * first node in insertion order; all values at indices ≥ {@link #size()} are UNSET.
    */
-  @NullableDecl private transient int[] predecessor;
+  @CheckForNull private transient int[] predecessor;
 
   /**
    * Pointer to the successor of an entry in insertion order. ENDPOINT indicates a node is the last
    * node in insertion order; all values at indices ≥ {@link #size()} are UNSET.
    */
-  @NullableDecl private transient int[] successor;
+  @CheckForNull private transient int[] successor;
 
   /** Pointer to the first node in the linked list, or {@code ENDPOINT} if there are no entries. */
   private transient int firstEntry;
@@ -149,21 +155,27 @@ Set<E> convertToHashFloodingResistantImplementation() {
     return result;
   }
 
+  /*
+   * For discussion of the safety of the following methods for operating on predecessors and
+   * successors, see the comments near the end of CompactHashMap, noting that the methods here call
+   * requirePredecessors() and requireSuccessors(), which are defined at the end of this file.
+   */
+
   private int getPredecessor(int entry) {
-    return predecessor[entry] - 1;
+    return requirePredecessors()[entry] - 1;
   }
 
   @Override
   int getSuccessor(int entry) {
-    return successor[entry] - 1;
+    return requireSuccessors()[entry] - 1;
   }
 
   private void setSuccessor(int entry, int succ) {
-    successor[entry] = succ + 1;
+    requireSuccessors()[entry] = succ + 1;
   }
 
   private void setPredecessor(int entry, int pred) {
-    predecessor[entry] = pred + 1;
+    requirePredecessors()[entry] = pred + 1;
   }
 
   private void setSucceeds(int pred, int succ) {
@@ -181,7 +193,7 @@ private void setSucceeds(int pred, int succ) {
   }
 
   @Override
-  void insertEntry(int entryIndex, @NullableDecl E object, int hash, int mask) {
+  void insertEntry(int entryIndex, @ParametricNullness E object, int hash, int mask) {
     super.insertEntry(entryIndex, object, hash, mask);
     setSucceeds(lastEntry, entryIndex);
     setSucceeds(entryIndex, ENDPOINT);
@@ -197,15 +209,15 @@ void moveLastEntry(int dstIndex, int mask) {
       setSucceeds(getPredecessor(srcIndex), dstIndex);
       setSucceeds(dstIndex, getSuccessor(srcIndex));
     }
-    predecessor[srcIndex] = 0;
-    successor[srcIndex] = 0;
+    requirePredecessors()[srcIndex] = 0;
+    requireSuccessors()[srcIndex] = 0;
   }
 
   @Override
   void resizeEntries(int newCapacity) {
     super.resizeEntries(newCapacity);
-    predecessor = Arrays.copyOf(predecessor, newCapacity);
-    successor = Arrays.copyOf(successor, newCapacity);
+    predecessor = Arrays.copyOf(requirePredecessors(), newCapacity);
+    successor = Arrays.copyOf(requireSuccessors(), newCapacity);
   }
 
   @Override
@@ -219,12 +231,13 @@ int adjustAfterRemove(int indexBeforeRemove, int indexRemoved) {
   }
 
   @Override
-  public Object[] toArray() {
+  public @Nullable Object[] toArray() {
     return ObjectArrays.toArrayImpl(this);
   }
 
   @Override
-  public <T> T[] toArray(T[] a) {
+  @SuppressWarnings("nullness") // b/192354773 in our checker affects toArray declarations
+  public <T extends @Nullable Object> T[] toArray(T[] a) {
     return ObjectArrays.toArrayImpl(this, a);
   }
 
@@ -235,10 +248,30 @@ public void clear() {
     }
     this.firstEntry = ENDPOINT;
     this.lastEntry = ENDPOINT;
-    if (predecessor != null) {
+    // Either both arrays are null or neither is, but we check both to satisfy the nullness checker.
+    if (predecessor != null && successor != null) {
       Arrays.fill(predecessor, 0, size(), 0);
       Arrays.fill(successor, 0, size(), 0);
     }
     super.clear();
   }
+
+  /*
+   * For discussion of the safety of the following methods, see the comments near the end of
+   * CompactHashMap.
+   */
+
+  private int[] requirePredecessors() {
+    return requireNonNull(predecessor);
+  }
+
+  private int[] requireSuccessors() {
+    return requireNonNull(successor);
+  }
+
+  /*
+   * We don't define getPredecessor+getSuccessor and setPredecessor+setSuccessor here because
+   * they're defined above -- including logic to add and subtract 1 to map between the values stored
+   * in the predecessor/successor arrays and the indexes in the elements array that they identify.
+   */
 }
diff --git a/android/guava/src/com/google/common/collect/ComparatorOrdering.java b/android/guava/src/com/google/common/collect/ComparatorOrdering.java
index a40892003e64..8b3407074421 100644
--- a/android/guava/src/com/google/common/collect/ComparatorOrdering.java
+++ b/android/guava/src/com/google/common/collect/ComparatorOrdering.java
@@ -21,11 +21,14 @@
 import com.google.common.annotations.GwtCompatible;
 import java.io.Serializable;
 import java.util.Comparator;
-import org.checkerframework.checker.nullness.compatqual.NullableDecl;
+import javax.annotation.CheckForNull;
+import org.checkerframework.checker.nullness.qual.Nullable;
 
 /** An ordering for a pre-existing comparator. */
 @GwtCompatible(serializable = true)
-final class ComparatorOrdering<T> extends Ordering<T> implements Serializable {
+@ElementTypesAreNonnullByDefault
+final class ComparatorOrdering<T extends @Nullable Object> extends Ordering<T>
+    implements Serializable {
   final Comparator<T> comparator;
 
   ComparatorOrdering(Comparator<T> comparator) {
@@ -33,12 +36,12 @@ final class ComparatorOrdering<T> extends Ordering<T> implements Serializable {
   }
 
   @Override
-  public int compare(T a, T b) {
+  public int compare(@ParametricNullness T a, @ParametricNullness T b) {
     return comparator.compare(a, b);
   }
 
   @Override
-  public boolean equals(@NullableDecl Object object) {
+  public boolean equals(@CheckForNull Object object) {
     if (object == this) {
       return true;
     }
diff --git a/android/guava/src/com/google/common/collect/Comparators.java b/android/guava/src/com/google/common/collect/Comparators.java
index 555e5b80bfaa..0c79a8c29b34 100644
--- a/android/guava/src/com/google/common/collect/Comparators.java
+++ b/android/guava/src/com/google/common/collect/Comparators.java
@@ -18,11 +18,10 @@
 
 import static com.google.common.base.Preconditions.checkNotNull;
 
-import com.google.common.annotations.Beta;
 import com.google.common.annotations.GwtCompatible;
 import java.util.Comparator;
 import java.util.Iterator;
-import org.checkerframework.checker.nullness.compatqual.NullableDecl;
+import org.checkerframework.checker.nullness.qual.Nullable;
 
 /**
  * Provides static methods for working with {@link Comparator} instances. For many other helpful
@@ -39,8 +38,8 @@
  * @since 21.0
  * @author Louis Wasserman
  */
-@Beta
 @GwtCompatible
+@ElementTypesAreNonnullByDefault
 public final class Comparators {
   private Comparators() {}
 
@@ -58,7 +57,8 @@ private Comparators() {}
   // Note: 90% of the time we don't add type parameters or wildcards that serve only to "tweak" the
   // desired return type. However, *nested* generics introduce a special class of problems that we
   // think tip it over into being worthwhile.
-  public static <T, S extends T> Comparator<Iterable<S>> lexicographical(Comparator<T> comparator) {
+  public static <T extends @Nullable Object, S extends T> Comparator<Iterable<S>> lexicographical(
+      Comparator<T> comparator) {
     return new LexicographicalOrdering<S>(checkNotNull(comparator));
   }
 
@@ -67,7 +67,8 @@ public static <T, S extends T> Comparator<Iterable<S>> lexicographical(Comparato
    * equal to the element that preceded it, according to the specified comparator. Note that this is
    * always true when the iterable has fewer than two elements.
    */
-  public static <T> boolean isInOrder(Iterable<? extends T> iterable, Comparator<T> comparator) {
+  public static <T extends @Nullable Object> boolean isInOrder(
+      Iterable<? extends T> iterable, Comparator<T> comparator) {
     checkNotNull(comparator);
     Iterator<? extends T> it = iterable.iterator();
     if (it.hasNext()) {
@@ -88,7 +89,7 @@ public static <T> boolean isInOrder(Iterable<? extends T> iterable, Comparator<T
    * greater than the element that preceded it, according to the specified comparator. Note that
    * this is always true when the iterable has fewer than two elements.
    */
-  public static <T> boolean isInStrictOrder(
+  public static <T extends @Nullable Object> boolean isInStrictOrder(
       Iterable<? extends T> iterable, Comparator<T> comparator) {
     checkNotNull(comparator);
     Iterator<? extends T> it = iterable.iterator();
@@ -118,7 +119,6 @@ public static <T> boolean isInStrictOrder(
    * @throws ClassCastException if the parameters are not <i>mutually comparable</i>.
    * @since 30.0
    */
-  @Beta
   public static <T extends Comparable<? super T>> T min(T a, T b) {
     return (a.compareTo(b) <= 0) ? a : b;
   }
@@ -138,8 +138,9 @@ public static <T extends Comparable<? super T>> T min(T a, T b) {
    *     comparator.
    * @since 30.0
    */
-  @Beta
-  public static <T> T min(@NullableDecl T a, @NullableDecl T b, Comparator<T> comparator) {
+  @ParametricNullness
+  public static <T extends @Nullable Object> T min(
+      @ParametricNullness T a, @ParametricNullness T b, Comparator<T> comparator) {
     return (comparator.compare(a, b) <= 0) ? a : b;
   }
 
@@ -156,7 +157,6 @@ public static <T> T min(@NullableDecl T a, @NullableDecl T b, Comparator<T> comp
    * @throws ClassCastException if the parameters are not <i>mutually comparable</i>.
    * @since 30.0
    */
-  @Beta
   public static <T extends Comparable<? super T>> T max(T a, T b) {
     return (a.compareTo(b) >= 0) ? a : b;
   }
@@ -176,8 +176,9 @@ public static <T extends Comparable<? super T>> T max(T a, T b) {
    *     comparator.
    * @since 30.0
    */
-  @Beta
-  public static <T> T max(@NullableDecl T a, @NullableDecl T b, Comparator<T> comparator) {
+  @ParametricNullness
+  public static <T extends @Nullable Object> T max(
+      @ParametricNullness T a, @ParametricNullness T b, Comparator<T> comparator) {
     return (comparator.compare(a, b) >= 0) ? a : b;
   }
 }
diff --git a/android/guava/src/com/google/common/collect/ComparisonChain.java b/android/guava/src/com/google/common/collect/ComparisonChain.java
index 2f748961949a..9c05205ec01d 100644
--- a/android/guava/src/com/google/common/collect/ComparisonChain.java
+++ b/android/guava/src/com/google/common/collect/ComparisonChain.java
@@ -21,7 +21,7 @@
 import com.google.common.primitives.Ints;
 import com.google.common.primitives.Longs;
 import java.util.Comparator;
-import org.checkerframework.checker.nullness.compatqual.NullableDecl;
+import org.checkerframework.checker.nullness.qual.Nullable;
 
 /**
  * A utility for performing a chained comparison statement. For example:
@@ -49,7 +49,7 @@
  * the presence of expensive {@code compareTo} and {@code compare} implementations.
  *
  * <p>See the Guava User Guide article on <a href=
- * "https://github.com/google/guava/wiki/CommonObjectUtilitiesExplained#comparecompareto"> {@code
+ * "https://github.com/google/guava/wiki/CommonObjectUtilitiesExplained#comparecompareto">{@code
  * ComparisonChain}</a>.
  *
  * @author Mark Davis
@@ -57,6 +57,7 @@
  * @since 2.0
  */
 @GwtCompatible
+@ElementTypesAreNonnullByDefault
 public abstract class ComparisonChain {
   private ComparisonChain() {}
 
@@ -67,15 +68,15 @@ public static ComparisonChain start() {
 
   private static final ComparisonChain ACTIVE =
       new ComparisonChain() {
-        @SuppressWarnings("unchecked")
+        @SuppressWarnings("unchecked") // unsafe; see discussion on supertype
         @Override
-        public ComparisonChain compare(Comparable left, Comparable right) {
-          return classify(left.compareTo(right));
+        public ComparisonChain compare(Comparable<?> left, Comparable<?> right) {
+          return classify(((Comparable<Object>) left).compareTo(right));
         }
 
         @Override
-        public <T> ComparisonChain compare(
-            @NullableDecl T left, @NullableDecl T right, Comparator<T> comparator) {
+        public <T extends @Nullable Object> ComparisonChain compare(
+            @ParametricNullness T left, @ParametricNullness T right, Comparator<T> comparator) {
           return classify(comparator.compare(left, right));
         }
 
@@ -131,13 +132,13 @@ private static final class InactiveComparisonChain extends ComparisonChain {
     }
 
     @Override
-    public ComparisonChain compare(@NullableDecl Comparable left, @NullableDecl Comparable right) {
+    public ComparisonChain compare(Comparable<?> left, Comparable<?> right) {
       return this;
     }
 
     @Override
-    public <T> ComparisonChain compare(
-        @NullableDecl T left, @NullableDecl T right, @NullableDecl Comparator<T> comparator) {
+    public <T extends @Nullable Object> ComparisonChain compare(
+        @ParametricNullness T left, @ParametricNullness T right, Comparator<T> comparator) {
       return this;
     }
 
@@ -180,6 +181,18 @@ public int result() {
   /**
    * Compares two comparable objects as specified by {@link Comparable#compareTo}, <i>if</i> the
    * result of this comparison chain has not already been determined.
+   *
+   * <p>This method is declared to accept any 2 {@code Comparable} objects, even if they are not <a
+   * href="https://docs.oracle.com/javase/tutorial/collections/interfaces/order.html">mutually
+   * comparable</a>. If you pass objects that are not mutually comparable, this method may throw an
+   * exception. (The reason for this decision is lost to time, but the reason <i>might</i> be that
+   * we wanted to support legacy classes that implement the raw type {@code Comparable} (instead of
+   * implementing {@code Comparable<Foo>}) without producing warnings. If so, we would prefer today
+   * to produce warnings in that case, and we may change this method to do so in the future. Support
+   * for raw {@code Comparable} types in Guava in general is tracked as <a
+   * href="https://github.com/google/guava/issues/989">#989</a>.)
+   *
+   * @throws ClassCastException if the parameters are not mutually comparable
    */
   public abstract ComparisonChain compare(Comparable<?> left, Comparable<?> right);
 
@@ -187,8 +200,8 @@ public int result() {
    * Compares two objects using a comparator, <i>if</i> the result of this comparison chain has not
    * already been determined.
    */
-  public abstract <T> ComparisonChain compare(
-      @NullableDecl T left, @NullableDecl T right, Comparator<T> comparator);
+  public abstract <T extends @Nullable Object> ComparisonChain compare(
+      @ParametricNullness T left, @ParametricNullness T right, Comparator<T> comparator);
 
   /**
    * Compares two {@code int} values as specified by {@link Ints#compare}, <i>if</i> the result of
diff --git a/android/guava/src/com/google/common/collect/CompoundOrdering.java b/android/guava/src/com/google/common/collect/CompoundOrdering.java
index e803acb4fbb7..42feed373193 100644
--- a/android/guava/src/com/google/common/collect/CompoundOrdering.java
+++ b/android/guava/src/com/google/common/collect/CompoundOrdering.java
@@ -20,10 +20,14 @@
 import java.io.Serializable;
 import java.util.Arrays;
 import java.util.Comparator;
+import javax.annotation.CheckForNull;
+import org.checkerframework.checker.nullness.qual.Nullable;
 
 /** An ordering that tries several comparators in order. */
 @GwtCompatible(serializable = true)
-final class CompoundOrdering<T> extends Ordering<T> implements Serializable {
+@ElementTypesAreNonnullByDefault
+final class CompoundOrdering<T extends @Nullable Object> extends Ordering<T>
+    implements Serializable {
   final Comparator<? super T>[] comparators;
 
   CompoundOrdering(Comparator<? super T> primary, Comparator<? super T> secondary) {
@@ -35,7 +39,7 @@ final class CompoundOrdering<T> extends Ordering<T> implements Serializable {
   }
 
   @Override
-  public int compare(T left, T right) {
+  public int compare(@ParametricNullness T left, @ParametricNullness T right) {
     for (int i = 0; i < comparators.length; i++) {
       int result = comparators[i].compare(left, right);
       if (result != 0) {
@@ -46,7 +50,7 @@ public int compare(T left, T right) {
   }
 
   @Override
-  public boolean equals(Object object) {
+  public boolean equals(@CheckForNull Object object) {
     if (object == this) {
       return true;
     }
diff --git a/android/guava/src/com/google/common/collect/ComputationException.java b/android/guava/src/com/google/common/collect/ComputationException.java
index dc569da3544b..b05577c412cc 100644
--- a/android/guava/src/com/google/common/collect/ComputationException.java
+++ b/android/guava/src/com/google/common/collect/ComputationException.java
@@ -17,7 +17,7 @@
 package com.google.common.collect;
 
 import com.google.common.annotations.GwtCompatible;
-import org.checkerframework.checker.nullness.compatqual.NullableDecl;
+import javax.annotation.CheckForNull;
 
 /**
  * Wraps an exception that occurred during a computation.
@@ -34,9 +34,10 @@
  */
 @Deprecated
 @GwtCompatible
+@ElementTypesAreNonnullByDefault
 public class ComputationException extends RuntimeException {
   /** Creates a new instance with the given cause. */
-  public ComputationException(@NullableDecl Throwable cause) {
+  public ComputationException(@CheckForNull Throwable cause) {
     super(cause);
   }
 
diff --git a/android/guava/src/com/google/common/collect/ConcurrentHashMultiset.java b/android/guava/src/com/google/common/collect/ConcurrentHashMultiset.java
index 8bdfca32d0d4..47248412bffa 100644
--- a/android/guava/src/com/google/common/collect/ConcurrentHashMultiset.java
+++ b/android/guava/src/com/google/common/collect/ConcurrentHashMultiset.java
@@ -18,8 +18,8 @@
 
 import static com.google.common.base.Preconditions.checkArgument;
 import static com.google.common.base.Preconditions.checkNotNull;
+import static com.google.common.base.Preconditions.checkState;
 import static com.google.common.collect.CollectPreconditions.checkNonnegative;
-import static com.google.common.collect.CollectPreconditions.checkRemove;
 
 import com.google.common.annotations.Beta;
 import com.google.common.annotations.GwtIncompatible;
@@ -41,21 +41,22 @@
 import java.util.concurrent.ConcurrentHashMap;
 import java.util.concurrent.ConcurrentMap;
 import java.util.concurrent.atomic.AtomicInteger;
-import org.checkerframework.checker.nullness.compatqual.NullableDecl;
+import javax.annotation.CheckForNull;
+import org.checkerframework.checker.nullness.qual.Nullable;
 
 /**
  * A multiset that supports concurrent modifications and that provides atomic versions of most
  * {@code Multiset} operations (exceptions where noted). Null elements are not supported.
  *
  * <p>See the Guava User Guide article on <a href=
- * "https://github.com/google/guava/wiki/NewCollectionTypesExplained#multiset"> {@code
- * Multiset}</a>.
+ * "https://github.com/google/guava/wiki/NewCollectionTypesExplained#multiset">{@code Multiset}</a>.
  *
  * @author Cliff L. Biffle
  * @author mike nonemacher
  * @since 2.0
  */
 @GwtIncompatible
+@ElementTypesAreNonnullByDefault
 public final class ConcurrentHashMultiset<E> extends AbstractMultiset<E> implements Serializable {
 
   /*
@@ -86,7 +87,7 @@ public static <E> ConcurrentHashMultiset<E> create() {
     // TODO(schmoe): provide a way to use this class with other (possibly arbitrary)
     // ConcurrentMap implementors. One possibility is to extract most of this class into
     // an AbstractConcurrentMapMultiset.
-    return new ConcurrentHashMultiset<E>(new ConcurrentHashMap<E, AtomicInteger>());
+    return new ConcurrentHashMultiset<>(new ConcurrentHashMap<E, AtomicInteger>());
   }
 
   /**
@@ -119,7 +120,7 @@ public static <E> ConcurrentHashMultiset<E> create(Iterable<? extends E> element
    */
   @Beta
   public static <E> ConcurrentHashMultiset<E> create(ConcurrentMap<E, AtomicInteger> countMap) {
-    return new ConcurrentHashMultiset<E>(countMap);
+    return new ConcurrentHashMultiset<>(countMap);
   }
 
   @VisibleForTesting
@@ -137,7 +138,7 @@ public static <E> ConcurrentHashMultiset<E> create(ConcurrentMap<E, AtomicIntege
    * @return the nonnegative number of occurrences of the element
    */
   @Override
-  public int count(@NullableDecl Object element) {
+  public int count(@CheckForNull Object element) {
     AtomicInteger existingCounter = Maps.safeGet(countMap, element);
     return (existingCounter == null) ? 0 : existingCounter.get();
   }
@@ -168,7 +169,8 @@ public Object[] toArray() {
   }
 
   @Override
-  public <T> T[] toArray(T[] array) {
+  @SuppressWarnings("nullness") // b/192354773 in our checker affects toArray declarations
+  public <T extends @Nullable Object> T[] toArray(T[] array) {
     return snapshot().toArray(array);
   }
 
@@ -205,7 +207,7 @@ public int add(E element, int occurrences) {
     if (occurrences == 0) {
       return count(element);
     }
-    CollectPreconditions.checkPositive(occurrences, "occurences");
+    CollectPreconditions.checkPositive(occurrences, "occurrences");
 
     while (true) {
       AtomicInteger existingCounter = Maps.safeGet(countMap, element);
@@ -261,17 +263,17 @@ public int add(E element, int occurrences) {
    * if occurrences == 0. This satisfies both NullPointerTester and
    * CollectionRemoveTester.testRemove_nullAllowed, but it's not clear that it's
    * a good policy, especially because, in order for the test to pass, the
-   * parameter must be misleadingly annotated as @NullableDecl. I suspect that
-   * we'll want to remove @NullableDecl, add an eager checkNotNull, and loosen up
+   * parameter must be misleadingly annotated as @Nullable. I suspect that
+   * we'll want to remove @Nullable, add an eager checkNotNull, and loosen up
    * testRemove_nullAllowed.
    */
   @CanIgnoreReturnValue
   @Override
-  public int remove(@NullableDecl Object element, int occurrences) {
+  public int remove(@CheckForNull Object element, int occurrences) {
     if (occurrences == 0) {
       return count(element);
     }
-    CollectPreconditions.checkPositive(occurrences, "occurences");
+    CollectPreconditions.checkPositive(occurrences, "occurrences");
 
     AtomicInteger existingCounter = Maps.safeGet(countMap, element);
     if (existingCounter == null) {
@@ -308,11 +310,11 @@ public int remove(@NullableDecl Object element, int occurrences) {
    * @throws IllegalArgumentException if {@code occurrences} is negative
    */
   @CanIgnoreReturnValue
-  public boolean removeExactly(@NullableDecl Object element, int occurrences) {
+  public boolean removeExactly(@CheckForNull Object element, int occurrences) {
     if (occurrences == 0) {
       return true;
     }
-    CollectPreconditions.checkPositive(occurrences, "occurences");
+    CollectPreconditions.checkPositive(occurrences, "occurrences");
 
     AtomicInteger existingCounter = Maps.safeGet(countMap, element);
     if (existingCounter == null) {
@@ -446,7 +448,7 @@ public boolean setCount(E element, int expectedOldCount, int newCount) {
 
   @Override
   Set<E> createElementSet() {
-    final Set<E> delegate = countMap.keySet();
+    Set<E> delegate = countMap.keySet();
     return new ForwardingSet<E>() {
       @Override
       protected Set<E> delegate() {
@@ -454,7 +456,7 @@ protected Set<E> delegate() {
       }
 
       @Override
-      public boolean contains(@NullableDecl Object object) {
+      public boolean contains(@CheckForNull Object object) {
         return object != null && Collections2.safeContains(delegate, object);
       }
 
@@ -464,7 +466,7 @@ public boolean containsAll(Collection<?> collection) {
       }
 
       @Override
-      public boolean remove(Object object) {
+      public boolean remove(@CheckForNull Object object) {
         return object != null && Collections2.safeRemove(delegate, object);
       }
 
@@ -501,12 +503,13 @@ public boolean isEmpty() {
   Iterator<Entry<E>> entryIterator() {
     // AbstractIterator makes this fairly clean, but it doesn't support remove(). To support
     // remove(), we create an AbstractIterator, and then use ForwardingIterator to delegate to it.
-    final Iterator<Entry<E>> readOnlyIterator =
+    Iterator<Entry<E>> readOnlyIterator =
         new AbstractIterator<Entry<E>>() {
           private final Iterator<Map.Entry<E, AtomicInteger>> mapEntries =
               countMap.entrySet().iterator();
 
           @Override
+          @CheckForNull
           protected Entry<E> computeNext() {
             while (true) {
               if (!mapEntries.hasNext()) {
@@ -522,7 +525,7 @@ protected Entry<E> computeNext() {
         };
 
     return new ForwardingIterator<Entry<E>>() {
-      @NullableDecl private Entry<E> last;
+      @CheckForNull private Entry<E> last;
 
       @Override
       protected Iterator<Entry<E>> delegate() {
@@ -537,7 +540,7 @@ public Entry<E> next() {
 
       @Override
       public void remove() {
-        checkRemove(last != null);
+        checkState(last != null, "no calls to next() since the last call to remove()");
         ConcurrentHashMultiset.this.setCount(last.getElement(), 0);
         last = null;
       }
@@ -572,7 +575,8 @@ public Object[] toArray() {
     }
 
     @Override
-    public <T> T[] toArray(T[] array) {
+    @SuppressWarnings("nullness") // b/192354773 in our checker affects toArray declarations
+    public <T extends @Nullable Object> T[] toArray(T[] array) {
       return snapshot().toArray(array);
     }
 
diff --git a/android/guava/src/com/google/common/collect/ConsumingQueueIterator.java b/android/guava/src/com/google/common/collect/ConsumingQueueIterator.java
index 2f288f041f4e..7721e1277ca8 100644
--- a/android/guava/src/com/google/common/collect/ConsumingQueueIterator.java
+++ b/android/guava/src/com/google/common/collect/ConsumingQueueIterator.java
@@ -17,29 +17,30 @@
 import static com.google.common.base.Preconditions.checkNotNull;
 
 import com.google.common.annotations.GwtCompatible;
-import java.util.ArrayDeque;
-import java.util.Collections;
 import java.util.Queue;
+import javax.annotation.CheckForNull;
+import org.checkerframework.checker.nullness.qual.Nullable;
 
 /**
  * An Iterator implementation which draws elements from a queue, removing them from the queue as it
  * iterates.
  */
 @GwtCompatible
-class ConsumingQueueIterator<T> extends AbstractIterator<T> {
+@ElementTypesAreNonnullByDefault
+final class ConsumingQueueIterator<T extends @Nullable Object> extends AbstractIterator<T> {
   private final Queue<T> queue;
 
-  ConsumingQueueIterator(T... elements) {
-    this.queue = new ArrayDeque<T>(elements.length);
-    Collections.addAll(queue, elements);
-  }
-
   ConsumingQueueIterator(Queue<T> queue) {
     this.queue = checkNotNull(queue);
   }
 
   @Override
+  @CheckForNull
   public T computeNext() {
-    return queue.isEmpty() ? endOfData() : queue.remove();
+    // TODO(b/192579700): Use a ternary once it no longer confuses our nullness checker.
+    if (queue.isEmpty()) {
+      return endOfData();
+    }
+    return queue.remove();
   }
 }
diff --git a/android/guava/src/com/google/common/collect/ContiguousSet.java b/android/guava/src/com/google/common/collect/ContiguousSet.java
index 9002b8e47684..b3e4889d7cf7 100644
--- a/android/guava/src/com/google/common/collect/ContiguousSet.java
+++ b/android/guava/src/com/google/common/collect/ContiguousSet.java
@@ -16,6 +16,7 @@
 
 import static com.google.common.base.Preconditions.checkArgument;
 import static com.google.common.base.Preconditions.checkNotNull;
+import static java.util.Objects.requireNonNull;
 
 import com.google.common.annotations.Beta;
 import com.google.common.annotations.GwtCompatible;
@@ -49,6 +50,7 @@
  */
 @GwtCompatible(emulated = true)
 @SuppressWarnings("rawtypes") // allow ungenerified Comparable types
+@ElementTypesAreNonnullByDefault
 public abstract class ContiguousSet<C extends Comparable> extends ImmutableSortedSet<C> {
   /**
    * Returns a {@code ContiguousSet} containing the same values in the given domain {@linkplain
@@ -74,13 +76,19 @@ public static <C extends Comparable> ContiguousSet<C> create(
       throw new IllegalArgumentException(e);
     }
 
-    // Per class spec, we are allowed to throw CCE if necessary
-    boolean empty =
-        effectiveRange.isEmpty()
-            || Range.compareOrThrow(
-                    range.lowerBound.leastValueAbove(domain),
-                    range.upperBound.greatestValueBelow(domain))
-                > 0;
+    boolean empty;
+    if (effectiveRange.isEmpty()) {
+      empty = true;
+    } else {
+      /*
+       * requireNonNull is safe because the effectiveRange operations above would have thrown or
+       * effectiveRange.isEmpty() would have returned true.
+       */
+      C afterLower = requireNonNull(range.lowerBound.leastValueAbove(domain));
+      C beforeUpper = requireNonNull(range.upperBound.greatestValueBelow(domain));
+      // Per class spec, we are allowed to throw CCE if necessary
+      empty = Range.compareOrThrow(afterLower, beforeUpper) > 0;
+    }
 
     return empty
         ? new EmptyContiguousSet<C>(domain)
@@ -234,7 +242,7 @@ abstract ContiguousSet<C> subSetImpl(
   @Override
   @GwtIncompatible // NavigableSet
   ImmutableSortedSet<C> createDescendingSet() {
-    return new DescendingImmutableSortedSet<C>(this);
+    return new DescendingImmutableSortedSet<>(this);
   }
 
   /** Returns a short-hand representation of the contents such as {@code "[1..100]"}. */
diff --git a/android/guava/src/com/google/common/collect/Count.java b/android/guava/src/com/google/common/collect/Count.java
index 9a0ea41d9cba..7aa555080135 100644
--- a/android/guava/src/com/google/common/collect/Count.java
+++ b/android/guava/src/com/google/common/collect/Count.java
@@ -16,7 +16,7 @@
 
 import com.google.common.annotations.GwtCompatible;
 import java.io.Serializable;
-import org.checkerframework.checker.nullness.compatqual.NullableDecl;
+import javax.annotation.CheckForNull;
 
 /**
  * A mutable value of type {@code int}, for multisets to use in tracking counts of values.
@@ -24,6 +24,7 @@
  * @author Louis Wasserman
  */
 @GwtCompatible
+@ElementTypesAreNonnullByDefault
 final class Count implements Serializable {
   private int value;
 
@@ -59,7 +60,7 @@ public int hashCode() {
   }
 
   @Override
-  public boolean equals(@NullableDecl Object obj) {
+  public boolean equals(@CheckForNull Object obj) {
     return obj instanceof Count && ((Count) obj).value == value;
   }
 
diff --git a/android/guava/src/com/google/common/collect/Cut.java b/android/guava/src/com/google/common/collect/Cut.java
index b792d84e0403..21fe5ff2dd9f 100644
--- a/android/guava/src/com/google/common/collect/Cut.java
+++ b/android/guava/src/com/google/common/collect/Cut.java
@@ -20,7 +20,7 @@
 import com.google.common.primitives.Booleans;
 import java.io.Serializable;
 import java.util.NoSuchElementException;
-import org.checkerframework.checker.nullness.compatqual.NullableDecl;
+import javax.annotation.CheckForNull;
 
 /**
  * Implementation detail for the internal structure of {@link Range} instances. Represents a unique
@@ -32,10 +32,11 @@
  * @author Kevin Bourrillion
  */
 @GwtCompatible
+@ElementTypesAreNonnullByDefault
 abstract class Cut<C extends Comparable> implements Comparable<Cut<C>>, Serializable {
-  @NullableDecl final C endpoint;
+  final C endpoint;
 
-  Cut(@NullableDecl C endpoint) {
+  Cut(C endpoint) {
     this.endpoint = endpoint;
   }
 
@@ -53,8 +54,10 @@ abstract class Cut<C extends Comparable> implements Comparable<Cut<C>>, Serializ
 
   abstract void describeAsUpperBound(StringBuilder sb);
 
+  @CheckForNull
   abstract C leastValueAbove(DiscreteDomain<C> domain);
 
+  @CheckForNull
   abstract C greatestValueBelow(DiscreteDomain<C> domain);
 
   /*
@@ -88,14 +91,15 @@ C endpoint() {
 
   @SuppressWarnings("unchecked") // catching CCE
   @Override
-  public boolean equals(Object obj) {
+  public boolean equals(@CheckForNull Object obj) {
     if (obj instanceof Cut) {
       // It might not really be a Cut<C>, but we'll catch a CCE if it's not
       Cut<C> that = (Cut<C>) obj;
       try {
         int compareResult = compareTo(that);
         return compareResult == 0;
-      } catch (ClassCastException ignored) {
+      } catch (ClassCastException wastNotComparableToOurType) {
+        return false;
       }
     }
     return false;
@@ -120,7 +124,13 @@ private static final class BelowAll extends Cut<Comparable<?>> {
     private static final BelowAll INSTANCE = new BelowAll();
 
     private BelowAll() {
-      super(null);
+      /*
+       * No code ever sees this bogus value for `endpoint`: This class overrides both methods that
+       * use the `endpoint` field, compareTo() and endpoint(). Additionally, the main implementation
+       * of Cut.compareTo checks for belowAll before reading accessing `endpoint` on another Cut
+       * instance.
+       */
+      super("");
     }
 
     @Override
@@ -219,7 +229,8 @@ private static final class AboveAll extends Cut<Comparable<?>> {
     private static final AboveAll INSTANCE = new AboveAll();
 
     private AboveAll() {
-      super(null);
+      // For discussion of "", see BelowAll.
+      super("");
     }
 
     @Override
@@ -297,7 +308,7 @@ private Object readResolve() {
   }
 
   static <C extends Comparable> Cut<C> belowValue(C endpoint) {
-    return new BelowValue<C>(endpoint);
+    return new BelowValue<>(endpoint);
   }
 
   private static final class BelowValue<C extends Comparable> extends Cut<C> {
@@ -326,7 +337,7 @@ Cut<C> withLowerBoundType(BoundType boundType, DiscreteDomain<C> domain) {
         case CLOSED:
           return this;
         case OPEN:
-          @NullableDecl C previous = domain.previous(endpoint);
+          C previous = domain.previous(endpoint);
           return (previous == null) ? Cut.<C>belowAll() : new AboveValue<C>(previous);
         default:
           throw new AssertionError();
@@ -337,7 +348,7 @@ Cut<C> withLowerBoundType(BoundType boundType, DiscreteDomain<C> domain) {
     Cut<C> withUpperBoundType(BoundType boundType, DiscreteDomain<C> domain) {
       switch (boundType) {
         case CLOSED:
-          @NullableDecl C previous = domain.previous(endpoint);
+          C previous = domain.previous(endpoint);
           return (previous == null) ? Cut.<C>aboveAll() : new AboveValue<C>(previous);
         case OPEN:
           return this;
@@ -362,6 +373,7 @@ C leastValueAbove(DiscreteDomain<C> domain) {
     }
 
     @Override
+    @CheckForNull
     C greatestValueBelow(DiscreteDomain<C> domain) {
       return domain.previous(endpoint);
     }
@@ -380,7 +392,7 @@ public String toString() {
   }
 
   static <C extends Comparable> Cut<C> aboveValue(C endpoint) {
-    return new AboveValue<C>(endpoint);
+    return new AboveValue<>(endpoint);
   }
 
   private static final class AboveValue<C extends Comparable> extends Cut<C> {
@@ -409,7 +421,7 @@ Cut<C> withLowerBoundType(BoundType boundType, DiscreteDomain<C> domain) {
         case OPEN:
           return this;
         case CLOSED:
-          @NullableDecl C next = domain.next(endpoint);
+          C next = domain.next(endpoint);
           return (next == null) ? Cut.<C>belowAll() : belowValue(next);
         default:
           throw new AssertionError();
@@ -420,7 +432,7 @@ Cut<C> withLowerBoundType(BoundType boundType, DiscreteDomain<C> domain) {
     Cut<C> withUpperBoundType(BoundType boundType, DiscreteDomain<C> domain) {
       switch (boundType) {
         case OPEN:
-          @NullableDecl C next = domain.next(endpoint);
+          C next = domain.next(endpoint);
           return (next == null) ? Cut.<C>aboveAll() : belowValue(next);
         case CLOSED:
           return this;
@@ -440,6 +452,7 @@ void describeAsUpperBound(StringBuilder sb) {
     }
 
     @Override
+    @CheckForNull
     C leastValueAbove(DiscreteDomain<C> domain) {
       return domain.next(endpoint);
     }
diff --git a/android/guava/src/com/google/common/collect/DenseImmutableTable.java b/android/guava/src/com/google/common/collect/DenseImmutableTable.java
index 4e28c899ae4a..9de77c57f213 100644
--- a/android/guava/src/com/google/common/collect/DenseImmutableTable.java
+++ b/android/guava/src/com/google/common/collect/DenseImmutableTable.java
@@ -14,16 +14,20 @@
 
 package com.google.common.collect;
 
+import static java.util.Objects.requireNonNull;
+
 import com.google.common.annotations.GwtCompatible;
 import com.google.common.collect.ImmutableMap.IteratorBasedImmutableMap;
 import com.google.errorprone.annotations.Immutable;
 import com.google.j2objc.annotations.WeakOuter;
 import java.util.Map;
-import org.checkerframework.checker.nullness.compatqual.NullableDecl;
+import javax.annotation.CheckForNull;
+import org.checkerframework.checker.nullness.qual.Nullable;
 
 /** A {@code RegularImmutableTable} optimized for dense data. */
 @GwtCompatible
 @Immutable(containerOf = {"R", "C", "V"})
+@ElementTypesAreNonnullByDefault
 final class DenseImmutableTable<R, C, V> extends RegularImmutableTable<R, C, V> {
   private final ImmutableMap<R, Integer> rowKeyToIndex;
   private final ImmutableMap<C, Integer> columnKeyToIndex;
@@ -37,7 +41,7 @@ final class DenseImmutableTable<R, C, V> extends RegularImmutableTable<R, C, V>
   private final int[] columnCounts;
 
   @SuppressWarnings("Immutable") // We don't modify this after construction.
-  private final V[][] values;
+  private final @Nullable V[][] values;
 
   // For each cell in iteration order, the index of that cell's row key in the row key list.
   @SuppressWarnings("Immutable") // We don't modify this after construction.
@@ -52,7 +56,8 @@ final class DenseImmutableTable<R, C, V> extends RegularImmutableTable<R, C, V>
       ImmutableSet<R> rowSpace,
       ImmutableSet<C> columnSpace) {
     @SuppressWarnings("unchecked")
-    V[][] array = (V[][]) new Object[rowSpace.size()][columnSpace.size()];
+    @Nullable
+    V[][] array = (@Nullable V[][]) new Object[rowSpace.size()][columnSpace.size()];
     this.values = array;
     this.rowKeyToIndex = Maps.indexMap(rowSpace);
     this.columnKeyToIndex = Maps.indexMap(columnSpace);
@@ -64,8 +69,9 @@ final class DenseImmutableTable<R, C, V> extends RegularImmutableTable<R, C, V>
       Cell<R, C, V> cell = cellList.get(i);
       R rowKey = cell.getRowKey();
       C columnKey = cell.getColumnKey();
-      int rowIndex = rowKeyToIndex.get(rowKey);
-      int columnIndex = columnKeyToIndex.get(columnKey);
+      // The requireNonNull calls are safe because we construct the indexes with indexMap.
+      int rowIndex = requireNonNull(rowKeyToIndex.get(rowKey));
+      int columnIndex = requireNonNull(columnKeyToIndex.get(columnKey));
       V existingValue = values[rowIndex][columnIndex];
       checkNoDuplicate(rowKey, columnKey, existingValue, cell.getValue());
       values[rowIndex][columnIndex] = cell.getValue();
@@ -99,7 +105,7 @@ K getKey(int index) {
       return keyToIndex().keySet().asList().get(index);
     }
 
-    @NullableDecl
+    @CheckForNull
     abstract V getValue(int keyIndex);
 
     @Override
@@ -113,7 +119,8 @@ public int size() {
     }
 
     @Override
-    public V get(@NullableDecl Object key) {
+    @CheckForNull
+    public V get(@CheckForNull Object key) {
       Integer keyIndex = keyToIndex().get(key);
       return (keyIndex == null) ? null : getValue(keyIndex);
     }
@@ -125,6 +132,7 @@ UnmodifiableIterator<Entry<K, V>> entryIterator() {
         private final int maxIndex = keyToIndex().size();
 
         @Override
+        @CheckForNull
         protected Entry<K, V> computeNext() {
           for (index++; index < maxIndex; index++) {
             V value = getValue(index);
@@ -152,6 +160,7 @@ ImmutableMap<C, Integer> keyToIndex() {
     }
 
     @Override
+    @CheckForNull
     V getValue(int keyIndex) {
       return values[rowIndex][keyIndex];
     }
@@ -176,6 +185,7 @@ ImmutableMap<R, Integer> keyToIndex() {
     }
 
     @Override
+    @CheckForNull
     V getValue(int keyIndex) {
       return values[keyIndex][columnIndex];
     }
@@ -245,7 +255,8 @@ public ImmutableMap<R, Map<C, V>> rowMap() {
   }
 
   @Override
-  public V get(@NullableDecl Object rowKey, @NullableDecl Object columnKey) {
+  @CheckForNull
+  public V get(@CheckForNull Object rowKey, @CheckForNull Object columnKey) {
     Integer rowIndex = rowKeyToIndex.get(rowKey);
     Integer columnIndex = columnKeyToIndex.get(columnKey);
     return ((rowIndex == null) || (columnIndex == null)) ? null : values[rowIndex][columnIndex];
@@ -262,13 +273,15 @@ Cell<R, C, V> getCell(int index) {
     int columnIndex = cellColumnIndices[index];
     R rowKey = rowKeySet().asList().get(rowIndex);
     C columnKey = columnKeySet().asList().get(columnIndex);
-    V value = values[rowIndex][columnIndex];
+    // requireNonNull is safe because we use indexes that were populated by the constructor.
+    V value = requireNonNull(values[rowIndex][columnIndex]);
     return cellOf(rowKey, columnKey, value);
   }
 
   @Override
   V getValue(int index) {
-    return values[cellRowIndices[index]][cellColumnIndices[index]];
+    // requireNonNull is safe because we use indexes that were populated by the constructor.
+    return requireNonNull(values[cellRowIndices[index]][cellColumnIndices[index]]);
   }
 
   @Override
diff --git a/android/guava/src/com/google/common/collect/DescendingImmutableSortedMultiset.java b/android/guava/src/com/google/common/collect/DescendingImmutableSortedMultiset.java
index 189acdb5fd26..181731cc4896 100644
--- a/android/guava/src/com/google/common/collect/DescendingImmutableSortedMultiset.java
+++ b/android/guava/src/com/google/common/collect/DescendingImmutableSortedMultiset.java
@@ -15,7 +15,7 @@
 package com.google.common.collect;
 
 import com.google.common.annotations.GwtIncompatible;
-import org.checkerframework.checker.nullness.compatqual.NullableDecl;
+import javax.annotation.CheckForNull;
 
 /**
  * A descending wrapper around an {@code ImmutableSortedMultiset}
@@ -24,6 +24,7 @@
  */
 @SuppressWarnings("serial") // uses writeReplace, not default serialization
 @GwtIncompatible
+@ElementTypesAreNonnullByDefault
 final class DescendingImmutableSortedMultiset<E> extends ImmutableSortedMultiset<E> {
   private final transient ImmutableSortedMultiset<E> forward;
 
@@ -32,16 +33,18 @@ final class DescendingImmutableSortedMultiset<E> extends ImmutableSortedMultiset
   }
 
   @Override
-  public int count(@NullableDecl Object element) {
+  public int count(@CheckForNull Object element) {
     return forward.count(element);
   }
 
   @Override
+  @CheckForNull
   public Entry<E> firstEntry() {
     return forward.lastEntry();
   }
 
   @Override
+  @CheckForNull
   public Entry<E> lastEntry() {
     return forward.firstEntry();
   }
diff --git a/android/guava/src/com/google/common/collect/DescendingImmutableSortedSet.java b/android/guava/src/com/google/common/collect/DescendingImmutableSortedSet.java
index 64e3e89acb07..88c7d6b5cca0 100644
--- a/android/guava/src/com/google/common/collect/DescendingImmutableSortedSet.java
+++ b/android/guava/src/com/google/common/collect/DescendingImmutableSortedSet.java
@@ -17,7 +17,7 @@
 package com.google.common.collect;
 
 import com.google.common.annotations.GwtIncompatible;
-import org.checkerframework.checker.nullness.compatqual.NullableDecl;
+import javax.annotation.CheckForNull;
 
 /**
  * Skeletal implementation of {@link ImmutableSortedSet#descendingSet()}.
@@ -25,6 +25,7 @@
  * @author Louis Wasserman
  */
 @GwtIncompatible
+@ElementTypesAreNonnullByDefault
 final class DescendingImmutableSortedSet<E> extends ImmutableSortedSet<E> {
   private final ImmutableSortedSet<E> forward;
 
@@ -34,7 +35,7 @@ final class DescendingImmutableSortedSet<E> extends ImmutableSortedSet<E> {
   }
 
   @Override
-  public boolean contains(@NullableDecl Object object) {
+  public boolean contains(@CheckForNull Object object) {
     return forward.contains(object);
   }
 
@@ -83,27 +84,31 @@ ImmutableSortedSet<E> createDescendingSet() {
   }
 
   @Override
+  @CheckForNull
   public E lower(E element) {
     return forward.higher(element);
   }
 
   @Override
+  @CheckForNull
   public E floor(E element) {
     return forward.ceiling(element);
   }
 
   @Override
+  @CheckForNull
   public E ceiling(E element) {
     return forward.floor(element);
   }
 
   @Override
+  @CheckForNull
   public E higher(E element) {
     return forward.lower(element);
   }
 
   @Override
-  int indexOf(@NullableDecl Object target) {
+  int indexOf(@CheckForNull Object target) {
     int index = forward.indexOf(target);
     if (index == -1) {
       return index;
diff --git a/android/guava/src/com/google/common/collect/DescendingMultiset.java b/android/guava/src/com/google/common/collect/DescendingMultiset.java
index 72a88af8ad2b..7db0fbbd4916 100644
--- a/android/guava/src/com/google/common/collect/DescendingMultiset.java
+++ b/android/guava/src/com/google/common/collect/DescendingMultiset.java
@@ -22,7 +22,8 @@
 import java.util.Iterator;
 import java.util.NavigableSet;
 import java.util.Set;
-import org.checkerframework.checker.nullness.compatqual.NullableDecl;
+import javax.annotation.CheckForNull;
+import org.checkerframework.checker.nullness.qual.Nullable;
 
 /**
  * A skeleton implementation of a descending multiset. Only needs {@code forwardMultiset()} and
@@ -31,10 +32,12 @@
  * @author Louis Wasserman
  */
 @GwtCompatible(emulated = true)
-abstract class DescendingMultiset<E> extends ForwardingMultiset<E> implements SortedMultiset<E> {
+@ElementTypesAreNonnullByDefault
+abstract class DescendingMultiset<E extends @Nullable Object> extends ForwardingMultiset<E>
+    implements SortedMultiset<E> {
   abstract SortedMultiset<E> forwardMultiset();
 
-  @NullableDecl private transient Comparator<? super E> comparator;
+  @CheckForNull private transient Comparator<? super E> comparator;
 
   @Override
   public Comparator<? super E> comparator() {
@@ -45,42 +48,47 @@ public Comparator<? super E> comparator() {
     return result;
   }
 
-  @NullableDecl private transient NavigableSet<E> elementSet;
+  @CheckForNull private transient NavigableSet<E> elementSet;
 
   @Override
   public NavigableSet<E> elementSet() {
     NavigableSet<E> result = elementSet;
     if (result == null) {
-      return elementSet = new SortedMultisets.NavigableElementSet<E>(this);
+      return elementSet = new SortedMultisets.NavigableElementSet<>(this);
     }
     return result;
   }
 
   @Override
+  @CheckForNull
   public Entry<E> pollFirstEntry() {
     return forwardMultiset().pollLastEntry();
   }
 
   @Override
+  @CheckForNull
   public Entry<E> pollLastEntry() {
     return forwardMultiset().pollFirstEntry();
   }
 
   @Override
-  public SortedMultiset<E> headMultiset(E toElement, BoundType boundType) {
+  public SortedMultiset<E> headMultiset(@ParametricNullness E toElement, BoundType boundType) {
     return forwardMultiset().tailMultiset(toElement, boundType).descendingMultiset();
   }
 
   @Override
   public SortedMultiset<E> subMultiset(
-      E fromElement, BoundType fromBoundType, E toElement, BoundType toBoundType) {
+      @ParametricNullness E fromElement,
+      BoundType fromBoundType,
+      @ParametricNullness E toElement,
+      BoundType toBoundType) {
     return forwardMultiset()
         .subMultiset(toElement, toBoundType, fromElement, fromBoundType)
         .descendingMultiset();
   }
 
   @Override
-  public SortedMultiset<E> tailMultiset(E fromElement, BoundType boundType) {
+  public SortedMultiset<E> tailMultiset(@ParametricNullness E fromElement, BoundType boundType) {
     return forwardMultiset().headMultiset(fromElement, boundType).descendingMultiset();
   }
 
@@ -95,18 +103,20 @@ public SortedMultiset<E> descendingMultiset() {
   }
 
   @Override
+  @CheckForNull
   public Entry<E> firstEntry() {
     return forwardMultiset().lastEntry();
   }
 
   @Override
+  @CheckForNull
   public Entry<E> lastEntry() {
     return forwardMultiset().firstEntry();
   }
 
   abstract Iterator<Entry<E>> entryIterator();
 
-  @NullableDecl private transient Set<Entry<E>> entrySet;
+  @CheckForNull private transient Set<Entry<E>> entrySet;
 
   @Override
   public Set<Entry<E>> entrySet() {
@@ -141,12 +151,13 @@ public Iterator<E> iterator() {
   }
 
   @Override
-  public Object[] toArray() {
+  public @Nullable Object[] toArray() {
     return standardToArray();
   }
 
   @Override
-  public <T> T[] toArray(T[] array) {
+  @SuppressWarnings("nullness") // b/192354773 in our checker affects toArray declarations
+  public <T extends @Nullable Object> T[] toArray(T[] array) {
     return standardToArray(array);
   }
 
diff --git a/android/guava/src/com/google/common/collect/DiscreteDomain.java b/android/guava/src/com/google/common/collect/DiscreteDomain.java
index 3777a6d4bbc9..222ebe5283f3 100644
--- a/android/guava/src/com/google/common/collect/DiscreteDomain.java
+++ b/android/guava/src/com/google/common/collect/DiscreteDomain.java
@@ -25,6 +25,7 @@
 import java.io.Serializable;
 import java.math.BigInteger;
 import java.util.NoSuchElementException;
+import javax.annotation.CheckForNull;
 
 /**
  * A descriptor for a <i>discrete</i> {@code Comparable} domain such as all {@link Integer}
@@ -36,13 +37,14 @@
  * represent partial domains such as "prime integers" or "strings of length 5."
  *
  * <p>See the Guava User Guide section on <a href=
- * "https://github.com/google/guava/wiki/RangesExplained#discrete-domains"> {@code
+ * "https://github.com/google/guava/wiki/RangesExplained#discrete-domains">{@code
  * DiscreteDomain}</a>.
  *
  * @author Kevin Bourrillion
  * @since 10.0
  */
 @GwtCompatible
+@ElementTypesAreNonnullByDefault
 public abstract class DiscreteDomain<C extends Comparable> {
 
   /**
@@ -62,12 +64,14 @@ private static final class IntegerDomain extends DiscreteDomain<Integer> impleme
     }
 
     @Override
+    @CheckForNull
     public Integer next(Integer value) {
       int i = value;
       return (i == Integer.MAX_VALUE) ? null : i + 1;
     }
 
     @Override
+    @CheckForNull
     public Integer previous(Integer value) {
       int i = value;
       return (i == Integer.MIN_VALUE) ? null : i - 1;
@@ -123,12 +127,14 @@ private static final class LongDomain extends DiscreteDomain<Long> implements Se
     }
 
     @Override
+    @CheckForNull
     public Long next(Long value) {
       long l = value;
       return (l == Long.MAX_VALUE) ? null : l + 1;
     }
 
     @Override
+    @CheckForNull
     public Long previous(Long value) {
       long l = value;
       return (l == Long.MIN_VALUE) ? null : l - 1;
@@ -248,11 +254,16 @@ private DiscreteDomain(boolean supportsFastOffset) {
    * #next} on {@code origin} {@code distance} times.
    */
   C offset(C origin, long distance) {
+    C current = origin;
     checkNonnegative(distance, "distance");
     for (long i = 0; i < distance; i++) {
-      origin = next(origin);
+      current = next(current);
+      if (current == null) {
+        throw new IllegalArgumentException(
+            "overflowed computing offset(" + origin + ", " + distance + ")");
+      }
     }
-    return origin;
+    return current;
   }
 
   /**
@@ -263,6 +274,7 @@ C offset(C origin, long distance) {
    * @return the least value greater than {@code value}, or {@code null} if {@code value} is {@code
    *     maxValue()}
    */
+  @CheckForNull
   public abstract C next(C value);
 
   /**
@@ -273,6 +285,7 @@ C offset(C origin, long distance) {
    * @return the greatest value less than {@code value}, or {@code null} if {@code value} is {@code
    *     minValue()}
    */
+  @CheckForNull
   public abstract C previous(C value);
 
   /**
diff --git a/android/guava/src/com/google/common/collect/ElementTypesAreNonnullByDefault.java b/android/guava/src/com/google/common/collect/ElementTypesAreNonnullByDefault.java
new file mode 100644
index 000000000000..e1c640ff5db4
--- /dev/null
+++ b/android/guava/src/com/google/common/collect/ElementTypesAreNonnullByDefault.java
@@ -0,0 +1,41 @@
+/*
+ * Copyright (C) 2021 The Guava Authors
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package com.google.common.collect;
+
+import static java.lang.annotation.ElementType.FIELD;
+import static java.lang.annotation.ElementType.METHOD;
+import static java.lang.annotation.ElementType.PARAMETER;
+import static java.lang.annotation.ElementType.TYPE;
+import static java.lang.annotation.RetentionPolicy.RUNTIME;
+
+import com.google.common.annotations.GwtCompatible;
+import java.lang.annotation.Retention;
+import java.lang.annotation.Target;
+import javax.annotation.Nonnull;
+import javax.annotation.meta.TypeQualifierDefault;
+
+/**
+ * Marks all "top-level" types as non-null in a way that is recognized by Kotlin. Note that this
+ * unfortunately includes type-variable usages, so we also provide {@link ParametricNullness} to
+ * "undo" it as best we can.
+ */
+@GwtCompatible
+@Retention(RUNTIME)
+@Target(TYPE)
+@TypeQualifierDefault({FIELD, METHOD, PARAMETER})
+@Nonnull
+@interface ElementTypesAreNonnullByDefault {}
diff --git a/android/guava/src/com/google/common/collect/EmptyContiguousSet.java b/android/guava/src/com/google/common/collect/EmptyContiguousSet.java
index 8043ef7880da..50d7b126a27a 100644
--- a/android/guava/src/com/google/common/collect/EmptyContiguousSet.java
+++ b/android/guava/src/com/google/common/collect/EmptyContiguousSet.java
@@ -18,7 +18,7 @@
 import java.io.Serializable;
 import java.util.NoSuchElementException;
 import java.util.Set;
-import org.checkerframework.checker.nullness.compatqual.NullableDecl;
+import javax.annotation.CheckForNull;
 
 /**
  * An empty contiguous set.
@@ -27,6 +27,7 @@
  */
 @GwtCompatible(emulated = true)
 @SuppressWarnings("rawtypes") // allow ungenerified Comparable types
+@ElementTypesAreNonnullByDefault
 final class EmptyContiguousSet<C extends Comparable> extends ContiguousSet<C> {
   EmptyContiguousSet(DiscreteDomain<C> domain) {
     super(domain);
@@ -79,13 +80,13 @@ ContiguousSet<C> tailSetImpl(C fromElement, boolean fromInclusive) {
   }
 
   @Override
-  public boolean contains(Object object) {
+  public boolean contains(@CheckForNull Object object) {
     return false;
   }
 
   @GwtIncompatible // not used by GWT emulation
   @Override
-  int indexOf(Object target) {
+  int indexOf(@CheckForNull Object target) {
     return -1;
   }
 
@@ -121,7 +122,7 @@ public String toString() {
   }
 
   @Override
-  public boolean equals(@NullableDecl Object object) {
+  public boolean equals(@CheckForNull Object object) {
     if (object instanceof Set) {
       Set<?> that = (Set<?>) object;
       return that.isEmpty();
@@ -149,7 +150,7 @@ private SerializedForm(DiscreteDomain<C> domain) {
     }
 
     private Object readResolve() {
-      return new EmptyContiguousSet<C>(domain);
+      return new EmptyContiguousSet<>(domain);
     }
 
     private static final long serialVersionUID = 0;
@@ -158,7 +159,7 @@ private Object readResolve() {
   @GwtIncompatible // serialization
   @Override
   Object writeReplace() {
-    return new SerializedForm<C>(domain);
+    return new SerializedForm<>(domain);
   }
 
   @GwtIncompatible // NavigableSet
diff --git a/android/guava/src/com/google/common/collect/EmptyImmutableListMultimap.java b/android/guava/src/com/google/common/collect/EmptyImmutableListMultimap.java
index 9b167fb38772..10d030fbda05 100644
--- a/android/guava/src/com/google/common/collect/EmptyImmutableListMultimap.java
+++ b/android/guava/src/com/google/common/collect/EmptyImmutableListMultimap.java
@@ -24,6 +24,7 @@
  * @author Jared Levy
  */
 @GwtCompatible(serializable = true)
+@ElementTypesAreNonnullByDefault
 class EmptyImmutableListMultimap extends ImmutableListMultimap<Object, Object> {
   static final EmptyImmutableListMultimap INSTANCE = new EmptyImmutableListMultimap();
 
diff --git a/android/guava/src/com/google/common/collect/EmptyImmutableSetMultimap.java b/android/guava/src/com/google/common/collect/EmptyImmutableSetMultimap.java
index ec2ce2e192b8..bd0a67aa087b 100644
--- a/android/guava/src/com/google/common/collect/EmptyImmutableSetMultimap.java
+++ b/android/guava/src/com/google/common/collect/EmptyImmutableSetMultimap.java
@@ -24,6 +24,7 @@
  * @author Mike Ward
  */
 @GwtCompatible(serializable = true)
+@ElementTypesAreNonnullByDefault
 class EmptyImmutableSetMultimap extends ImmutableSetMultimap<Object, Object> {
   static final EmptyImmutableSetMultimap INSTANCE = new EmptyImmutableSetMultimap();
 
diff --git a/android/guava/src/com/google/common/collect/EnumBiMap.java b/android/guava/src/com/google/common/collect/EnumBiMap.java
index f72b8b96f706..97d3c2e7cd09 100644
--- a/android/guava/src/com/google/common/collect/EnumBiMap.java
+++ b/android/guava/src/com/google/common/collect/EnumBiMap.java
@@ -32,12 +32,13 @@
  * An {@code EnumBiMap} and its inverse are both serializable.
  *
  * <p>See the Guava User Guide article on <a href=
- * "https://github.com/google/guava/wiki/NewCollectionTypesExplained#bimap"> {@code BiMap}</a>.
+ * "https://github.com/google/guava/wiki/NewCollectionTypesExplained#bimap">{@code BiMap}</a>.
  *
  * @author Mike Bostock
  * @since 2.0
  */
 @GwtCompatible(emulated = true)
+@ElementTypesAreNonnullByDefault
 public final class EnumBiMap<K extends Enum<K>, V extends Enum<V>> extends AbstractBiMap<K, V> {
   private transient Class<K> keyType;
   private transient Class<V> valueType;
diff --git a/android/guava/src/com/google/common/collect/EnumHashBiMap.java b/android/guava/src/com/google/common/collect/EnumHashBiMap.java
index 0a7e52e12756..5fbbb70c6303 100644
--- a/android/guava/src/com/google/common/collect/EnumHashBiMap.java
+++ b/android/guava/src/com/google/common/collect/EnumHashBiMap.java
@@ -27,7 +27,8 @@
 import java.util.EnumMap;
 import java.util.HashMap;
 import java.util.Map;
-import org.checkerframework.checker.nullness.compatqual.NullableDecl;
+import javax.annotation.CheckForNull;
+import org.checkerframework.checker.nullness.qual.Nullable;
 
 /**
  * A {@code BiMap} backed by an {@code EnumMap} instance for keys-to-values, and a {@code HashMap}
@@ -35,13 +36,15 @@
  * EnumHashBiMap} and its inverse are both serializable.
  *
  * <p>See the Guava User Guide article on <a href=
- * "https://github.com/google/guava/wiki/NewCollectionTypesExplained#bimap"> {@code BiMap}</a>.
+ * "https://github.com/google/guava/wiki/NewCollectionTypesExplained#bimap">{@code BiMap}</a>.
  *
  * @author Mike Bostock
  * @since 2.0
  */
 @GwtCompatible(emulated = true)
-public final class EnumHashBiMap<K extends Enum<K>, V> extends AbstractBiMap<K, V> {
+@ElementTypesAreNonnullByDefault
+public final class EnumHashBiMap<K extends Enum<K>, V extends @Nullable Object>
+    extends AbstractBiMap<K, V> {
   private transient Class<K> keyType;
 
   /**
@@ -49,7 +52,8 @@ public final class EnumHashBiMap<K extends Enum<K>, V> extends AbstractBiMap<K,
    *
    * @param keyType the key type
    */
-  public static <K extends Enum<K>, V> EnumHashBiMap<K, V> create(Class<K> keyType) {
+  public static <K extends Enum<K>, V extends @Nullable Object> EnumHashBiMap<K, V> create(
+      Class<K> keyType) {
     return new EnumHashBiMap<>(keyType);
   }
 
@@ -63,7 +67,8 @@ public static <K extends Enum<K>, V> EnumHashBiMap<K, V> create(Class<K> keyType
    * @throws IllegalArgumentException if map is not an {@code EnumBiMap} or an {@code EnumHashBiMap}
    *     instance and contains no mappings
    */
-  public static <K extends Enum<K>, V> EnumHashBiMap<K, V> create(Map<K, ? extends V> map) {
+  public static <K extends Enum<K>, V extends @Nullable Object> EnumHashBiMap<K, V> create(
+      Map<K, ? extends V> map) {
     EnumHashBiMap<K, V> bimap = create(EnumBiMap.inferKeyType(map));
     bimap.putAll(map);
     return bimap;
@@ -85,13 +90,19 @@ K checkKey(K key) {
 
   @CanIgnoreReturnValue
   @Override
-  public V put(K key, @NullableDecl V value) {
+  @SuppressWarnings("RedundantOverride") // b/192446478: RedundantOverride ignores some annotations.
+  // TODO(b/192446998): Remove this override after tools understand nullness better.
+  @CheckForNull
+  public V put(K key, @ParametricNullness V value) {
     return super.put(key, value);
   }
 
   @CanIgnoreReturnValue
   @Override
-  public V forcePut(K key, @NullableDecl V value) {
+  @SuppressWarnings("RedundantOverride") // b/192446478: RedundantOverride ignores some annotations.
+  // TODO(b/192446998): Remove this override after tools understand nullness better.
+  @CheckForNull
+  public V forcePut(K key, @ParametricNullness V value) {
     return super.forcePut(key, value);
   }
 
diff --git a/android/guava/src/com/google/common/collect/EnumMultiset.java b/android/guava/src/com/google/common/collect/EnumMultiset.java
index af0deef21bce..57a3a873e12e 100644
--- a/android/guava/src/com/google/common/collect/EnumMultiset.java
+++ b/android/guava/src/com/google/common/collect/EnumMultiset.java
@@ -30,20 +30,20 @@
 import java.util.Arrays;
 import java.util.Iterator;
 import java.util.NoSuchElementException;
-import org.checkerframework.checker.nullness.compatqual.NullableDecl;
+import javax.annotation.CheckForNull;
 
 /**
  * Multiset implementation specialized for enum elements, supporting all single-element operations
  * in O(1).
  *
  * <p>See the Guava User Guide article on <a href=
- * "https://github.com/google/guava/wiki/NewCollectionTypesExplained#multiset"> {@code
- * Multiset}</a>.
+ * "https://github.com/google/guava/wiki/NewCollectionTypesExplained#multiset">{@code Multiset}</a>.
  *
  * @author Jared Levy
  * @since 2.0
  */
 @GwtCompatible(emulated = true)
+@ElementTypesAreNonnullByDefault
 public final class EnumMultiset<E extends Enum<E>> extends AbstractMultiset<E>
     implements Serializable {
   /** Creates an empty {@code EnumMultiset}. */
@@ -93,7 +93,7 @@ private EnumMultiset(Class<E> type) {
     this.counts = new int[enumConstants.length];
   }
 
-  private boolean isActuallyE(@NullableDecl Object o) {
+  private boolean isActuallyE(@CheckForNull Object o) {
     if (o instanceof Enum) {
       Enum<?> e = (Enum<?>) o;
       int index = e.ordinal();
@@ -106,7 +106,7 @@ private boolean isActuallyE(@NullableDecl Object o) {
    * Returns {@code element} cast to {@code E}, if it actually is a nonnull E. Otherwise, throws
    * either a NullPointerException or a ClassCastException as appropriate.
    */
-  void checkIsE(@NullableDecl Object element) {
+  private void checkIsE(Object element) {
     checkNotNull(element);
     if (!isActuallyE(element)) {
       throw new ClassCastException("Expected an " + type + " but got " + element);
@@ -124,8 +124,9 @@ public int size() {
   }
 
   @Override
-  public int count(@NullableDecl Object element) {
-    if (!isActuallyE(element)) {
+  public int count(@CheckForNull Object element) {
+    // isActuallyE checks for null, but we check explicitly to help nullness checkers.
+    if (element == null || !isActuallyE(element)) {
       return 0;
     }
     Enum<?> e = (Enum<?>) element;
@@ -156,8 +157,9 @@ public int add(E element, int occurrences) {
   // Modification Operations
   @CanIgnoreReturnValue
   @Override
-  public int remove(@NullableDecl Object element, int occurrences) {
-    if (!isActuallyE(element)) {
+  public int remove(@CheckForNull Object element, int occurrences) {
+    // isActuallyE checks for null, but we check explicitly to help nullness checkers.
+    if (element == null || !isActuallyE(element)) {
       return 0;
     }
     Enum<?> e = (Enum<?>) element;
diff --git a/android/guava/src/com/google/common/collect/EvictingQueue.java b/android/guava/src/com/google/common/collect/EvictingQueue.java
index 37a65f3e0deb..5667dfa8c054 100644
--- a/android/guava/src/com/google/common/collect/EvictingQueue.java
+++ b/android/guava/src/com/google/common/collect/EvictingQueue.java
@@ -45,6 +45,7 @@
  */
 @Beta
 @GwtCompatible
+@ElementTypesAreNonnullByDefault
 public final class EvictingQueue<E> extends ForwardingQueue<E> implements Serializable {
 
   private final Queue<E> delegate;
@@ -53,7 +54,7 @@ public final class EvictingQueue<E> extends ForwardingQueue<E> implements Serial
 
   private EvictingQueue(int maxSize) {
     checkArgument(maxSize >= 0, "maxSize (%s) must >= 0", maxSize);
-    this.delegate = new ArrayDeque<E>(maxSize);
+    this.delegate = new ArrayDeque<>(maxSize);
     this.maxSize = maxSize;
   }
 
@@ -64,7 +65,7 @@ private EvictingQueue(int maxSize) {
    * queue.
    */
   public static <E> EvictingQueue<E> create(int maxSize) {
-    return new EvictingQueue<E>(maxSize);
+    return new EvictingQueue<>(maxSize);
   }
 
   /**
@@ -126,17 +127,19 @@ public boolean addAll(Collection<? extends E> collection) {
   }
 
   @Override
-  public boolean contains(Object object) {
-    return delegate().contains(checkNotNull(object));
+  public Object[] toArray() {
+    /*
+     * If we could, we'd declare the no-arg `Collection.toArray()` to return "Object[] but elements
+     * have the same nullness as E." Since we can't, we declare it to return nullable elements, and
+     * we can override it in our non-null-guaranteeing subtypes to present a better signature to
+     * their users.
+     *
+     * However, the checker *we* use has this special knowledge about `Collection.toArray()` anyway,
+     * so in our implementation code, we can rely on that. That's why the expression below
+     * type-checks.
+     */
+    return super.toArray();
   }
 
-  @Override
-  @CanIgnoreReturnValue
-  public boolean remove(Object object) {
-    return delegate().remove(checkNotNull(object));
-  }
-
-  // TODO(kak): Do we want to checkNotNull each element in containsAll, removeAll, and retainAll?
-
   private static final long serialVersionUID = 0L;
 }
diff --git a/android/guava/src/com/google/common/collect/ExplicitOrdering.java b/android/guava/src/com/google/common/collect/ExplicitOrdering.java
index 710c1aea0722..383318af5bb4 100644
--- a/android/guava/src/com/google/common/collect/ExplicitOrdering.java
+++ b/android/guava/src/com/google/common/collect/ExplicitOrdering.java
@@ -19,10 +19,11 @@
 import com.google.common.annotations.GwtCompatible;
 import java.io.Serializable;
 import java.util.List;
-import org.checkerframework.checker.nullness.compatqual.NullableDecl;
+import javax.annotation.CheckForNull;
 
 /** An ordering that compares objects according to a given order. */
 @GwtCompatible(serializable = true)
+@ElementTypesAreNonnullByDefault
 final class ExplicitOrdering<T> extends Ordering<T> implements Serializable {
   final ImmutableMap<T, Integer> rankMap;
 
@@ -48,7 +49,7 @@ private int rank(T value) {
   }
 
   @Override
-  public boolean equals(@NullableDecl Object object) {
+  public boolean equals(@CheckForNull Object object) {
     if (object instanceof ExplicitOrdering) {
       ExplicitOrdering<?> that = (ExplicitOrdering<?>) object;
       return this.rankMap.equals(that.rankMap);
diff --git a/android/guava/src/com/google/common/collect/FilteredEntryMultimap.java b/android/guava/src/com/google/common/collect/FilteredEntryMultimap.java
index 5860d885c625..de946a215f42 100644
--- a/android/guava/src/com/google/common/collect/FilteredEntryMultimap.java
+++ b/android/guava/src/com/google/common/collect/FilteredEntryMultimap.java
@@ -33,7 +33,8 @@
 import java.util.Map;
 import java.util.Map.Entry;
 import java.util.Set;
-import org.checkerframework.checker.nullness.compatqual.NullableDecl;
+import javax.annotation.CheckForNull;
+import org.checkerframework.checker.nullness.qual.Nullable;
 
 /**
  * Implementation of {@link Multimaps#filterEntries(Multimap, Predicate)}.
@@ -42,7 +43,9 @@
  * @author Louis Wasserman
  */
 @GwtCompatible
-class FilteredEntryMultimap<K, V> extends AbstractMultimap<K, V> implements FilteredMultimap<K, V> {
+@ElementTypesAreNonnullByDefault
+class FilteredEntryMultimap<K extends @Nullable Object, V extends @Nullable Object>
+    extends AbstractMultimap<K, V> implements FilteredMultimap<K, V> {
   final Multimap<K, V> unfiltered;
   final Predicate<? super Entry<K, V>> predicate;
 
@@ -66,24 +69,24 @@ public int size() {
     return entries().size();
   }
 
-  private boolean satisfies(K key, V value) {
+  private boolean satisfies(@ParametricNullness K key, @ParametricNullness V value) {
     return predicate.apply(Maps.immutableEntry(key, value));
   }
 
   final class ValuePredicate implements Predicate<V> {
-    private final K key;
+    @ParametricNullness private final K key;
 
-    ValuePredicate(K key) {
+    ValuePredicate(@ParametricNullness K key) {
       this.key = key;
     }
 
     @Override
-    public boolean apply(@NullableDecl V value) {
+    public boolean apply(@ParametricNullness V value) {
       return satisfies(key, value);
     }
   }
 
-  static <E> Collection<E> filterCollection(
+  static <E extends @Nullable Object> Collection<E> filterCollection(
       Collection<E> collection, Predicate<? super E> predicate) {
     if (collection instanceof Set) {
       return Sets.filter((Set<E>) collection, predicate);
@@ -93,12 +96,12 @@ static <E> Collection<E> filterCollection(
   }
 
   @Override
-  public boolean containsKey(@NullableDecl Object key) {
+  public boolean containsKey(@CheckForNull Object key) {
     return asMap().get(key) != null;
   }
 
   @Override
-  public Collection<V> removeAll(@NullableDecl Object key) {
+  public Collection<V> removeAll(@CheckForNull Object key) {
     return MoreObjects.firstNonNull(asMap().remove(key), unmodifiableEmptyCollection());
   }
 
@@ -115,7 +118,7 @@ public void clear() {
   }
 
   @Override
-  public Collection<V> get(final K key) {
+  public Collection<V> get(@ParametricNullness K key) {
     return filterCollection(unfiltered.get(key), new ValuePredicate(key));
   }
 
@@ -166,7 +169,7 @@ boolean removeEntriesIf(Predicate<? super Entry<K, Collection<V>>> predicate) {
   @WeakOuter
   class AsMap extends ViewCachingAbstractMap<K, Collection<V>> {
     @Override
-    public boolean containsKey(@NullableDecl Object key) {
+    public boolean containsKey(@CheckForNull Object key) {
       return get(key) != null;
     }
 
@@ -176,7 +179,8 @@ public void clear() {
     }
 
     @Override
-    public Collection<V> get(@NullableDecl Object key) {
+    @CheckForNull
+    public Collection<V> get(@CheckForNull Object key) {
       Collection<V> result = unfiltered.asMap().get(key);
       if (result == null) {
         return null;
@@ -188,7 +192,8 @@ public Collection<V> get(@NullableDecl Object key) {
     }
 
     @Override
-    public Collection<V> remove(@NullableDecl Object key) {
+    @CheckForNull
+    public Collection<V> remove(@CheckForNull Object key) {
       Collection<V> collection = unfiltered.asMap().get(key);
       if (collection == null) {
         return null;
@@ -232,7 +237,7 @@ public boolean retainAll(Collection<?> c) {
         }
 
         @Override
-        public boolean remove(@NullableDecl Object o) {
+        public boolean remove(@CheckForNull Object o) {
           return AsMap.this.remove(o) != null;
         }
       }
@@ -255,6 +260,7 @@ public Iterator<Entry<K, Collection<V>>> iterator() {
                 unfiltered.asMap().entrySet().iterator();
 
             @Override
+            @CheckForNull
             protected Entry<K, Collection<V>> computeNext() {
               while (backingIterator.hasNext()) {
                 Entry<K, Collection<V>> entry = backingIterator.next();
@@ -297,7 +303,7 @@ class ValuesImpl extends Maps.Values<K, Collection<V>> {
         }
 
         @Override
-        public boolean remove(@NullableDecl Object o) {
+        public boolean remove(@CheckForNull Object o) {
           if (o instanceof Collection) {
             Collection<?> c = (Collection<?>) o;
             Iterator<Entry<K, Collection<V>>> entryIterator =
@@ -346,7 +352,7 @@ class Keys extends Multimaps.Keys<K, V> {
     }
 
     @Override
-    public int remove(@NullableDecl Object key, int occurrences) {
+    public int remove(@CheckForNull Object key, int occurrences) {
       checkNonnegative(occurrences, "occurrences");
       if (occurrences == 0) {
         return count(key);
@@ -390,15 +396,11 @@ public int size() {
           return FilteredEntryMultimap.this.keySet().size();
         }
 
-        private boolean removeEntriesIf(final Predicate<? super Multiset.Entry<K>> predicate) {
+        private boolean removeEntriesIf(Predicate<? super Multiset.Entry<K>> predicate) {
           return FilteredEntryMultimap.this.removeEntriesIf(
-              new Predicate<Map.Entry<K, Collection<V>>>() {
-                @Override
-                public boolean apply(Map.Entry<K, Collection<V>> entry) {
-                  return predicate.apply(
-                      Multisets.immutableEntry(entry.getKey(), entry.getValue().size()));
-                }
-              });
+              (Map.Entry<K, Collection<V>> entry) ->
+                  predicate.apply(
+                      Multisets.immutableEntry(entry.getKey(), entry.getValue().size())));
         }
 
         @Override
diff --git a/android/guava/src/com/google/common/collect/FilteredEntrySetMultimap.java b/android/guava/src/com/google/common/collect/FilteredEntrySetMultimap.java
index 94740a4cf1a6..20413f8c4096 100644
--- a/android/guava/src/com/google/common/collect/FilteredEntrySetMultimap.java
+++ b/android/guava/src/com/google/common/collect/FilteredEntrySetMultimap.java
@@ -20,6 +20,8 @@
 import com.google.common.base.Predicate;
 import java.util.Map.Entry;
 import java.util.Set;
+import javax.annotation.CheckForNull;
+import org.checkerframework.checker.nullness.qual.Nullable;
 
 /**
  * Implementation of {@link Multimaps#filterEntries(SetMultimap, Predicate)}.
@@ -27,8 +29,9 @@
  * @author Louis Wasserman
  */
 @GwtCompatible
-final class FilteredEntrySetMultimap<K, V> extends FilteredEntryMultimap<K, V>
-    implements FilteredSetMultimap<K, V> {
+@ElementTypesAreNonnullByDefault
+final class FilteredEntrySetMultimap<K extends @Nullable Object, V extends @Nullable Object>
+    extends FilteredEntryMultimap<K, V> implements FilteredSetMultimap<K, V> {
 
   FilteredEntrySetMultimap(SetMultimap<K, V> unfiltered, Predicate<? super Entry<K, V>> predicate) {
     super(unfiltered, predicate);
@@ -40,17 +43,17 @@ public SetMultimap<K, V> unfiltered() {
   }
 
   @Override
-  public Set<V> get(K key) {
+  public Set<V> get(@ParametricNullness K key) {
     return (Set<V>) super.get(key);
   }
 
   @Override
-  public Set<V> removeAll(Object key) {
+  public Set<V> removeAll(@CheckForNull Object key) {
     return (Set<V>) super.removeAll(key);
   }
 
   @Override
-  public Set<V> replaceValues(K key, Iterable<? extends V> values) {
+  public Set<V> replaceValues(@ParametricNullness K key, Iterable<? extends V> values) {
     return (Set<V>) super.replaceValues(key, values);
   }
 
diff --git a/android/guava/src/com/google/common/collect/FilteredKeyListMultimap.java b/android/guava/src/com/google/common/collect/FilteredKeyListMultimap.java
index 2a5522541222..c82c8daf770d 100644
--- a/android/guava/src/com/google/common/collect/FilteredKeyListMultimap.java
+++ b/android/guava/src/com/google/common/collect/FilteredKeyListMultimap.java
@@ -19,7 +19,8 @@
 import com.google.common.annotations.GwtCompatible;
 import com.google.common.base.Predicate;
 import java.util.List;
-import org.checkerframework.checker.nullness.compatqual.NullableDecl;
+import javax.annotation.CheckForNull;
+import org.checkerframework.checker.nullness.qual.Nullable;
 
 /**
  * Implementation of {@link Multimaps#filterKeys(ListMultimap, Predicate)}.
@@ -27,8 +28,9 @@
  * @author Louis Wasserman
  */
 @GwtCompatible
-final class FilteredKeyListMultimap<K, V> extends FilteredKeyMultimap<K, V>
-    implements ListMultimap<K, V> {
+@ElementTypesAreNonnullByDefault
+final class FilteredKeyListMultimap<K extends @Nullable Object, V extends @Nullable Object>
+    extends FilteredKeyMultimap<K, V> implements ListMultimap<K, V> {
   FilteredKeyListMultimap(ListMultimap<K, V> unfiltered, Predicate<? super K> keyPredicate) {
     super(unfiltered, keyPredicate);
   }
@@ -39,17 +41,17 @@ public ListMultimap<K, V> unfiltered() {
   }
 
   @Override
-  public List<V> get(K key) {
+  public List<V> get(@ParametricNullness K key) {
     return (List<V>) super.get(key);
   }
 
   @Override
-  public List<V> removeAll(@NullableDecl Object key) {
+  public List<V> removeAll(@CheckForNull Object key) {
     return (List<V>) super.removeAll(key);
   }
 
   @Override
-  public List<V> replaceValues(K key, Iterable<? extends V> values) {
+  public List<V> replaceValues(@ParametricNullness K key, Iterable<? extends V> values) {
     return (List<V>) super.replaceValues(key, values);
   }
 }
diff --git a/android/guava/src/com/google/common/collect/FilteredKeyMultimap.java b/android/guava/src/com/google/common/collect/FilteredKeyMultimap.java
index 2a3003d15c92..68fad75b1445 100644
--- a/android/guava/src/com/google/common/collect/FilteredKeyMultimap.java
+++ b/android/guava/src/com/google/common/collect/FilteredKeyMultimap.java
@@ -16,6 +16,8 @@
 
 import static com.google.common.base.Preconditions.checkNotNull;
 import static com.google.common.base.Preconditions.checkPositionIndex;
+import static java.util.Collections.emptyList;
+import static java.util.Collections.emptySet;
 
 import com.google.common.annotations.GwtCompatible;
 import com.google.common.base.Predicate;
@@ -28,7 +30,8 @@
 import java.util.Map;
 import java.util.Map.Entry;
 import java.util.Set;
-import org.checkerframework.checker.nullness.compatqual.NullableDecl;
+import javax.annotation.CheckForNull;
+import org.checkerframework.checker.nullness.qual.Nullable;
 
 /**
  * Implementation of {@link Multimaps#filterKeys(Multimap, Predicate)}.
@@ -36,7 +39,9 @@
  * @author Louis Wasserman
  */
 @GwtCompatible
-class FilteredKeyMultimap<K, V> extends AbstractMultimap<K, V> implements FilteredMultimap<K, V> {
+@ElementTypesAreNonnullByDefault
+class FilteredKeyMultimap<K extends @Nullable Object, V extends @Nullable Object>
+    extends AbstractMultimap<K, V> implements FilteredMultimap<K, V> {
   final Multimap<K, V> unfiltered;
   final Predicate<? super K> keyPredicate;
 
@@ -65,7 +70,7 @@ public int size() {
   }
 
   @Override
-  public boolean containsKey(@NullableDecl Object key) {
+  public boolean containsKey(@CheckForNull Object key) {
     if (unfiltered.containsKey(key)) {
       @SuppressWarnings("unchecked") // k is equal to a K, if not one itself
       K k = (K) key;
@@ -75,15 +80,15 @@ public boolean containsKey(@NullableDecl Object key) {
   }
 
   @Override
-  public Collection<V> removeAll(Object key) {
+  public Collection<V> removeAll(@CheckForNull Object key) {
     return containsKey(key) ? unfiltered.removeAll(key) : unmodifiableEmptyCollection();
   }
 
   Collection<V> unmodifiableEmptyCollection() {
     if (unfiltered instanceof SetMultimap) {
-      return ImmutableSet.of();
+      return emptySet();
     } else {
-      return ImmutableList.of();
+      return emptyList();
     }
   }
 
@@ -98,7 +103,7 @@ Set<K> createKeySet() {
   }
 
   @Override
-  public Collection<V> get(K key) {
+  public Collection<V> get(@ParametricNullness K key) {
     if (keyPredicate.apply(key)) {
       return unfiltered.get(key);
     } else if (unfiltered instanceof SetMultimap) {
@@ -108,15 +113,16 @@ public Collection<V> get(K key) {
     }
   }
 
-  static class AddRejectingSet<K, V> extends ForwardingSet<V> {
-    final K key;
+  static class AddRejectingSet<K extends @Nullable Object, V extends @Nullable Object>
+      extends ForwardingSet<V> {
+    @ParametricNullness final K key;
 
-    AddRejectingSet(K key) {
+    AddRejectingSet(@ParametricNullness K key) {
       this.key = key;
     }
 
     @Override
-    public boolean add(V element) {
+    public boolean add(@ParametricNullness V element) {
       throw new IllegalArgumentException("Key does not satisfy predicate: " + key);
     }
 
@@ -132,21 +138,22 @@ protected Set<V> delegate() {
     }
   }
 
-  static class AddRejectingList<K, V> extends ForwardingList<V> {
-    final K key;
+  static class AddRejectingList<K extends @Nullable Object, V extends @Nullable Object>
+      extends ForwardingList<V> {
+    @ParametricNullness final K key;
 
-    AddRejectingList(K key) {
+    AddRejectingList(@ParametricNullness K key) {
       this.key = key;
     }
 
     @Override
-    public boolean add(V v) {
+    public boolean add(@ParametricNullness V v) {
       add(0, v);
       return true;
     }
 
     @Override
-    public void add(int index, V element) {
+    public void add(int index, @ParametricNullness V element) {
       checkPositionIndex(index, 0);
       throw new IllegalArgumentException("Key does not satisfy predicate: " + key);
     }
@@ -190,7 +197,7 @@ protected Collection<Entry<K, V>> delegate() {
 
     @Override
     @SuppressWarnings("unchecked")
-    public boolean remove(@NullableDecl Object o) {
+    public boolean remove(@CheckForNull Object o) {
       if (o instanceof Entry) {
         Entry<?, ?> entry = (Entry<?, ?>) o;
         if (unfiltered.containsKey(entry.getKey())
diff --git a/android/guava/src/com/google/common/collect/FilteredKeySetMultimap.java b/android/guava/src/com/google/common/collect/FilteredKeySetMultimap.java
index 1ec8e6532e39..e492a5c1dea9 100644
--- a/android/guava/src/com/google/common/collect/FilteredKeySetMultimap.java
+++ b/android/guava/src/com/google/common/collect/FilteredKeySetMultimap.java
@@ -20,7 +20,8 @@
 import com.google.common.base.Predicate;
 import java.util.Map.Entry;
 import java.util.Set;
-import org.checkerframework.checker.nullness.compatqual.NullableDecl;
+import javax.annotation.CheckForNull;
+import org.checkerframework.checker.nullness.qual.Nullable;
 
 /**
  * Implementation of {@link Multimaps#filterKeys(SetMultimap, Predicate)}.
@@ -28,8 +29,9 @@
  * @author Louis Wasserman
  */
 @GwtCompatible
-final class FilteredKeySetMultimap<K, V> extends FilteredKeyMultimap<K, V>
-    implements FilteredSetMultimap<K, V> {
+@ElementTypesAreNonnullByDefault
+final class FilteredKeySetMultimap<K extends @Nullable Object, V extends @Nullable Object>
+    extends FilteredKeyMultimap<K, V> implements FilteredSetMultimap<K, V> {
 
   FilteredKeySetMultimap(SetMultimap<K, V> unfiltered, Predicate<? super K> keyPredicate) {
     super(unfiltered, keyPredicate);
@@ -41,17 +43,17 @@ public SetMultimap<K, V> unfiltered() {
   }
 
   @Override
-  public Set<V> get(K key) {
+  public Set<V> get(@ParametricNullness K key) {
     return (Set<V>) super.get(key);
   }
 
   @Override
-  public Set<V> removeAll(Object key) {
+  public Set<V> removeAll(@CheckForNull Object key) {
     return (Set<V>) super.removeAll(key);
   }
 
   @Override
-  public Set<V> replaceValues(K key, Iterable<? extends V> values) {
+  public Set<V> replaceValues(@ParametricNullness K key, Iterable<? extends V> values) {
     return (Set<V>) super.replaceValues(key, values);
   }
 
@@ -72,7 +74,7 @@ public int hashCode() {
     }
 
     @Override
-    public boolean equals(@NullableDecl Object o) {
+    public boolean equals(@CheckForNull Object o) {
       return Sets.equalsImpl(this, o);
     }
   }
diff --git a/android/guava/src/com/google/common/collect/FilteredMultimap.java b/android/guava/src/com/google/common/collect/FilteredMultimap.java
index ef5ed4ab26f3..4e1fa066f80b 100644
--- a/android/guava/src/com/google/common/collect/FilteredMultimap.java
+++ b/android/guava/src/com/google/common/collect/FilteredMultimap.java
@@ -19,6 +19,7 @@
 import com.google.common.annotations.GwtCompatible;
 import com.google.common.base.Predicate;
 import java.util.Map.Entry;
+import org.checkerframework.checker.nullness.qual.Nullable;
 
 /**
  * An interface for all filtered multimap types.
@@ -26,7 +27,9 @@
  * @author Louis Wasserman
  */
 @GwtCompatible
-interface FilteredMultimap<K, V> extends Multimap<K, V> {
+@ElementTypesAreNonnullByDefault
+interface FilteredMultimap<K extends @Nullable Object, V extends @Nullable Object>
+    extends Multimap<K, V> {
   Multimap<K, V> unfiltered();
 
   Predicate<? super Entry<K, V>> entryPredicate();
diff --git a/android/guava/src/com/google/common/collect/FilteredMultimapValues.java b/android/guava/src/com/google/common/collect/FilteredMultimapValues.java
index b92707af5d57..ecbfab2a1d11 100644
--- a/android/guava/src/com/google/common/collect/FilteredMultimapValues.java
+++ b/android/guava/src/com/google/common/collect/FilteredMultimapValues.java
@@ -25,7 +25,8 @@
 import java.util.Collection;
 import java.util.Iterator;
 import java.util.Map.Entry;
-import org.checkerframework.checker.nullness.compatqual.NullableDecl;
+import javax.annotation.CheckForNull;
+import org.checkerframework.checker.nullness.qual.Nullable;
 
 /**
  * Implementation for {@link FilteredMultimap#values()}.
@@ -33,7 +34,9 @@
  * @author Louis Wasserman
  */
 @GwtCompatible
-final class FilteredMultimapValues<K, V> extends AbstractCollection<V> {
+@ElementTypesAreNonnullByDefault
+final class FilteredMultimapValues<K extends @Nullable Object, V extends @Nullable Object>
+    extends AbstractCollection<V> {
   @Weak private final FilteredMultimap<K, V> multimap;
 
   FilteredMultimapValues(FilteredMultimap<K, V> multimap) {
@@ -46,7 +49,7 @@ public Iterator<V> iterator() {
   }
 
   @Override
-  public boolean contains(@NullableDecl Object o) {
+  public boolean contains(@CheckForNull Object o) {
     return multimap.containsValue(o);
   }
 
@@ -56,7 +59,7 @@ public int size() {
   }
 
   @Override
-  public boolean remove(@NullableDecl Object o) {
+  public boolean remove(@CheckForNull Object o) {
     Predicate<? super Entry<K, V>> entryPredicate = multimap.entryPredicate();
     for (Iterator<Entry<K, V>> unfilteredItr = multimap.unfiltered().entries().iterator();
         unfilteredItr.hasNext(); ) {
diff --git a/android/guava/src/com/google/common/collect/FilteredSetMultimap.java b/android/guava/src/com/google/common/collect/FilteredSetMultimap.java
index a0a149fd7d5b..8e2ff7c0c1a6 100644
--- a/android/guava/src/com/google/common/collect/FilteredSetMultimap.java
+++ b/android/guava/src/com/google/common/collect/FilteredSetMultimap.java
@@ -17,6 +17,7 @@
 package com.google.common.collect;
 
 import com.google.common.annotations.GwtCompatible;
+import org.checkerframework.checker.nullness.qual.Nullable;
 
 /**
  * A supertype for filtered {@link SetMultimap} implementations.
@@ -24,7 +25,9 @@
  * @author Louis Wasserman
  */
 @GwtCompatible
-interface FilteredSetMultimap<K, V> extends FilteredMultimap<K, V>, SetMultimap<K, V> {
+@ElementTypesAreNonnullByDefault
+interface FilteredSetMultimap<K extends @Nullable Object, V extends @Nullable Object>
+    extends FilteredMultimap<K, V>, SetMultimap<K, V> {
   @Override
   SetMultimap<K, V> unfiltered();
 }
diff --git a/android/guava/src/com/google/common/collect/FluentIterable.java b/android/guava/src/com/google/common/collect/FluentIterable.java
index 66ae0986b037..72401d752ab9 100644
--- a/android/guava/src/com/google/common/collect/FluentIterable.java
+++ b/android/guava/src/com/google/common/collect/FluentIterable.java
@@ -24,13 +24,16 @@
 import com.google.common.base.Optional;
 import com.google.common.base.Predicate;
 import com.google.errorprone.annotations.CanIgnoreReturnValue;
+import com.google.errorprone.annotations.InlineMe;
 import java.util.Arrays;
 import java.util.Collection;
+import java.util.Collections;
 import java.util.Comparator;
 import java.util.Iterator;
 import java.util.List;
 import java.util.SortedSet;
-import org.checkerframework.checker.nullness.compatqual.NullableDecl;
+import javax.annotation.CheckForNull;
+import org.checkerframework.checker.nullness.qual.Nullable;
 
 /**
  * An expanded {@code Iterable} API, providing functionality similar to Java 8's powerful <a href=
@@ -109,11 +112,12 @@
  * @since 12.0
  */
 @GwtCompatible(emulated = true)
-public abstract class FluentIterable<E> implements Iterable<E> {
+@ElementTypesAreNonnullByDefault
+public abstract class FluentIterable<E extends @Nullable Object> implements Iterable<E> {
   // We store 'iterable' and use it instead of 'this' to allow Iterables to perform instanceof
   // checks on the _original_ iterable when FluentIterable.from is used.
   // To avoid a self retain cycle under j2objc, we store Optional.absent() instead of
-  // Optional.of(this). To access the iterator delegate, call #getDelegate(), which converts to
+  // Optional.of(this). To access the delegate iterable, call #getDelegate(), which converts to
   // absent() back to 'this'.
   private final Optional<Iterable<E>> iterableDelegate;
 
@@ -123,8 +127,7 @@ protected FluentIterable() {
   }
 
   FluentIterable(Iterable<E> iterable) {
-    checkNotNull(iterable);
-    this.iterableDelegate = Optional.fromNullable(this != iterable ? iterable : null);
+    this.iterableDelegate = Optional.of(iterable);
   }
 
   private Iterable<E> getDelegate() {
@@ -138,7 +141,7 @@ private Iterable<E> getDelegate() {
    * <p><b>{@code Stream} equivalent:</b> {@code iterable.stream()} if {@code iterable} is a {@link
    * Collection}; {@code StreamSupport.stream(iterable.spliterator(), false)} otherwise.
    */
-  public static <E> FluentIterable<E> from(final Iterable<E> iterable) {
+  public static <E extends @Nullable Object> FluentIterable<E> from(final Iterable<E> iterable) {
     return (iterable instanceof FluentIterable)
         ? (FluentIterable<E>) iterable
         : new FluentIterable<E>(iterable) {
@@ -160,7 +163,7 @@ public Iterator<E> iterator() {
    * @since 20.0 (since 18.0 as an overload of {@code of})
    */
   @Beta
-  public static <E> FluentIterable<E> from(E[] elements) {
+  public static <E extends @Nullable Object> FluentIterable<E> from(E[] elements) {
     return from(Arrays.asList(elements));
   }
 
@@ -173,7 +176,10 @@ public static <E> FluentIterable<E> from(E[] elements) {
    *     FluentIterable}
    */
   @Deprecated
-  public static <E> FluentIterable<E> from(FluentIterable<E> iterable) {
+  @InlineMe(
+      replacement = "checkNotNull(iterable)",
+      staticImports = {"com.google.common.base.Preconditions.checkNotNull"})
+  public static <E extends @Nullable Object> FluentIterable<E> from(FluentIterable<E> iterable) {
     return checkNotNull(iterable);
   }
 
@@ -190,7 +196,8 @@ public static <E> FluentIterable<E> from(FluentIterable<E> iterable) {
    * @since 20.0
    */
   @Beta
-  public static <T> FluentIterable<T> concat(Iterable<? extends T> a, Iterable<? extends T> b) {
+  public static <T extends @Nullable Object> FluentIterable<T> concat(
+      Iterable<? extends T> a, Iterable<? extends T> b) {
     return concatNoDefensiveCopy(a, b);
   }
 
@@ -208,7 +215,7 @@ public static <T> FluentIterable<T> concat(Iterable<? extends T> a, Iterable<? e
    * @since 20.0
    */
   @Beta
-  public static <T> FluentIterable<T> concat(
+  public static <T extends @Nullable Object> FluentIterable<T> concat(
       Iterable<? extends T> a, Iterable<? extends T> b, Iterable<? extends T> c) {
     return concatNoDefensiveCopy(a, b, c);
   }
@@ -228,7 +235,7 @@ public static <T> FluentIterable<T> concat(
    * @since 20.0
    */
   @Beta
-  public static <T> FluentIterable<T> concat(
+  public static <T extends @Nullable Object> FluentIterable<T> concat(
       Iterable<? extends T> a,
       Iterable<? extends T> b,
       Iterable<? extends T> c,
@@ -252,7 +259,8 @@ public static <T> FluentIterable<T> concat(
    * @since 20.0
    */
   @Beta
-  public static <T> FluentIterable<T> concat(Iterable<? extends T>... inputs) {
+  public static <T extends @Nullable Object> FluentIterable<T> concat(
+      Iterable<? extends T>... inputs) {
     return concatNoDefensiveCopy(Arrays.copyOf(inputs, inputs.length));
   }
 
@@ -271,7 +279,7 @@ public static <T> FluentIterable<T> concat(Iterable<? extends T>... inputs) {
    * @since 20.0
    */
   @Beta
-  public static <T> FluentIterable<T> concat(
+  public static <T extends @Nullable Object> FluentIterable<T> concat(
       final Iterable<? extends Iterable<? extends T>> inputs) {
     checkNotNull(inputs);
     return new FluentIterable<T>() {
@@ -283,7 +291,7 @@ public Iterator<T> iterator() {
   }
 
   /** Concatenates a varargs array of iterables without making a defensive copy of the array. */
-  private static <T> FluentIterable<T> concatNoDefensiveCopy(
+  private static <T extends @Nullable Object> FluentIterable<T> concatNoDefensiveCopy(
       final Iterable<? extends T>... inputs) {
     for (Iterable<? extends T> input : inputs) {
       checkNotNull(input);
@@ -311,8 +319,8 @@ public Iterator<? extends T> get(int i) {
    * @since 20.0
    */
   @Beta
-  public static <E> FluentIterable<E> of() {
-    return FluentIterable.from(ImmutableList.<E>of());
+  public static <E extends @Nullable Object> FluentIterable<E> of() {
+    return FluentIterable.from(Collections.<E>emptyList());
   }
 
   /**
@@ -324,7 +332,8 @@ public static <E> FluentIterable<E> of() {
    * @since 20.0
    */
   @Beta
-  public static <E> FluentIterable<E> of(@NullableDecl E element, E... elements) {
+  public static <E extends @Nullable Object> FluentIterable<E> of(
+      @ParametricNullness E element, E... elements) {
     return from(Lists.asList(element, elements));
   }
 
@@ -355,7 +364,7 @@ public final int size() {
    *
    * <p><b>{@code Stream} equivalent:</b> {@code stream.anyMatch(Predicate.isEqual(target))}.
    */
-  public final boolean contains(@NullableDecl Object target) {
+  public final boolean contains(@CheckForNull Object target) {
     return Iterables.contains(getDelegate(), target);
   }
 
@@ -465,6 +474,7 @@ public final boolean allMatch(Predicate<? super E> predicate) {
    *
    * <p><b>{@code Stream} equivalent:</b> {@code stream.filter(predicate).findFirst()}.
    */
+  @SuppressWarnings("nullness") // Unsafe, but we can't do much about it now.
   public final Optional<E> firstMatch(Predicate<? super E> predicate) {
     return Iterables.tryFind(getDelegate(), predicate);
   }
@@ -479,7 +489,8 @@ public final Optional<E> firstMatch(Predicate<? super E> predicate) {
    *
    * <p><b>{@code Stream} equivalent:</b> {@link Stream#map}.
    */
-  public final <T> FluentIterable<T> transform(Function<? super E, T> function) {
+  public final <T extends @Nullable Object> FluentIterable<T> transform(
+      Function<? super E, T> function) {
     return from(Iterables.transform(getDelegate(), function));
   }
 
@@ -496,7 +507,7 @@ public final <T> FluentIterable<T> transform(Function<? super E, T> function) {
    *
    * @since 13.0 (required {@code Function<E, Iterable<T>>} until 14.0)
    */
-  public <T> FluentIterable<T> transformAndConcat(
+  public <T extends @Nullable Object> FluentIterable<T> transformAndConcat(
       Function<? super E, ? extends Iterable<? extends T>> function) {
     return FluentIterable.concat(transform(function));
   }
@@ -511,6 +522,7 @@ public <T> FluentIterable<T> transformAndConcat(
    * @throws NullPointerException if the first element is null; if this is a possibility, use {@code
    *     iterator().next()} or {@link Iterables#getFirst} instead.
    */
+  @SuppressWarnings("nullness") // Unsafe, but we can't do much about it now.
   public final Optional<E> first() {
     Iterator<E> iterator = getDelegate().iterator();
     return iterator.hasNext() ? Optional.of(iterator.next()) : Optional.<E>absent();
@@ -527,6 +539,7 @@ public final Optional<E> first() {
    * @throws NullPointerException if the last element is null; if this is a possibility, use {@link
    *     Iterables#getLast} instead.
    */
+  @SuppressWarnings("nullness") // Unsafe, but we can't do much about it now.
   public final Optional<E> last() {
     // Iterables#getLast was inlined here so we don't have to throw/catch a NSEE
 
@@ -616,6 +629,7 @@ public final boolean isEmpty() {
    * @throws NullPointerException if any element is {@code null}
    * @since 14.0 (since 12.0 as {@code toImmutableList()}).
    */
+  @SuppressWarnings("nullness") // Unsafe, but we can't do much about it now.
   public final ImmutableList<E> toList() {
     return ImmutableList.copyOf(getDelegate());
   }
@@ -633,6 +647,7 @@ public final ImmutableList<E> toList() {
    * @throws NullPointerException if any element of this iterable is {@code null}
    * @since 14.0 (since 13.0 as {@code toSortedImmutableList()}).
    */
+  @SuppressWarnings("nullness") // Unsafe, but we can't do much about it now.
   public final ImmutableList<E> toSortedList(Comparator<? super E> comparator) {
     return Ordering.from(comparator).immutableSortedCopy(getDelegate());
   }
@@ -647,6 +662,7 @@ public final ImmutableList<E> toSortedList(Comparator<? super E> comparator) {
    * @throws NullPointerException if any element is {@code null}
    * @since 14.0 (since 12.0 as {@code toImmutableSet()}).
    */
+  @SuppressWarnings("nullness") // Unsafe, but we can't do much about it now.
   public final ImmutableSet<E> toSet() {
     return ImmutableSet.copyOf(getDelegate());
   }
@@ -665,6 +681,7 @@ public final ImmutableSet<E> toSet() {
    * @throws NullPointerException if any element of this iterable is {@code null}
    * @since 14.0 (since 12.0 as {@code toImmutableSortedSet()}).
    */
+  @SuppressWarnings("nullness") // Unsafe, but we can't do much about it now.
   public final ImmutableSortedSet<E> toSortedSet(Comparator<? super E> comparator) {
     return ImmutableSortedSet.copyOf(comparator, getDelegate());
   }
@@ -678,6 +695,7 @@ public final ImmutableSortedSet<E> toSortedSet(Comparator<? super E> comparator)
    * @throws NullPointerException if any element is null
    * @since 19.0
    */
+  @SuppressWarnings("nullness") // Unsafe, but we can't do much about it now.
   public final ImmutableMultiset<E> toMultiset() {
     return ImmutableMultiset.copyOf(getDelegate());
   }
@@ -699,6 +717,7 @@ public final ImmutableMultiset<E> toMultiset() {
    *     valueFunction} produces {@code null} for any key
    * @since 14.0
    */
+  @SuppressWarnings("nullness") // Unsafe, but we can't do much about it now.
   public final <V> ImmutableMap<E, V> toMap(Function<? super E, V> valueFunction) {
     return Maps.toMap(getDelegate(), valueFunction);
   }
@@ -721,6 +740,7 @@ public final <V> ImmutableMap<E, V> toMap(Function<? super E, V> valueFunction)
    *     keyFunction} produces {@code null} for any key
    * @since 14.0
    */
+  @SuppressWarnings("nullness") // Unsafe, but we can't do much about it now.
   public final <K> ImmutableListMultimap<K, E> index(Function<? super E, K> keyFunction) {
     return Multimaps.index(getDelegate(), keyFunction);
   }
@@ -757,6 +777,7 @@ public final <K> ImmutableListMultimap<K, E> index(Function<? super E, K> keyFun
    *     keyFunction} produces {@code null} for any key
    * @since 14.0
    */
+  @SuppressWarnings("nullness") // Unsafe, but we can't do much about it now.
   public final <K> ImmutableMap<K, E> uniqueIndex(Function<? super E, K> keyFunction) {
     return Maps.uniqueIndex(getDelegate(), keyFunction);
   }
@@ -774,7 +795,15 @@ public final <K> ImmutableMap<K, E> uniqueIndex(Function<? super E, K> keyFuncti
    *     copied
    */
   @GwtIncompatible // Array.newArray(Class, int)
-  public final E[] toArray(Class<E> type) {
+  /*
+   * Both the declaration of our Class<E> parameter and its usage in a call to Iterables.toArray
+   * produce a nullness error: E may be a nullable type, and our nullness checker has Class's type
+   * parameter bounded to non-null types. To avoid that, we'd use Class<@Nonnull E> if we could.
+   * (Granted, this is only one of many nullness-checking problems that arise from letting
+   * FluentIterable support null elements, and most of the other produce outright unsoundness.)
+   */
+  @SuppressWarnings("nullness")
+  public final @Nullable E[] toArray(Class<E> type) {
     return Iterables.toArray(getDelegate(), type);
   }
 
@@ -830,13 +859,14 @@ public final String join(Joiner joiner) {
    * @throws IndexOutOfBoundsException if {@code position} is negative or greater than or equal to
    *     the size of this fluent iterable
    */
-  // TODO(kevinb): add @NullableDecl?
+  @ParametricNullness
   public final E get(int position) {
     return Iterables.get(getDelegate(), position);
   }
 
   /** Function that transforms {@code Iterable<E>} into a fluent iterable. */
-  private static class FromIterableFunction<E> implements Function<Iterable<E>, FluentIterable<E>> {
+  private static class FromIterableFunction<E extends @Nullable Object>
+      implements Function<Iterable<E>, FluentIterable<E>> {
     @Override
     public FluentIterable<E> apply(Iterable<E> fromObject) {
       return FluentIterable.from(fromObject);
diff --git a/android/guava/src/com/google/common/collect/ForwardingBlockingDeque.java b/android/guava/src/com/google/common/collect/ForwardingBlockingDeque.java
index 7d3895d01502..49d4bcf6c232 100644
--- a/android/guava/src/com/google/common/collect/ForwardingBlockingDeque.java
+++ b/android/guava/src/com/google/common/collect/ForwardingBlockingDeque.java
@@ -20,6 +20,7 @@
 import java.util.Collection;
 import java.util.concurrent.BlockingDeque;
 import java.util.concurrent.TimeUnit;
+import javax.annotation.CheckForNull;
 
 /**
  * A {@link BlockingDeque} which forwards all its method calls to another {@code BlockingDeque}.
@@ -46,6 +47,7 @@
  */
 @Deprecated
 @GwtIncompatible
+@ElementTypesAreNonnullByDefault
 public abstract class ForwardingBlockingDeque<E> extends ForwardingDeque<E>
     implements BlockingDeque<E> {
 
@@ -91,11 +93,13 @@ public E takeLast() throws InterruptedException {
   }
 
   @Override
+  @CheckForNull
   public E pollFirst(long timeout, TimeUnit unit) throws InterruptedException {
     return delegate().pollFirst(timeout, unit);
   }
 
   @Override
+  @CheckForNull
   public E pollLast(long timeout, TimeUnit unit) throws InterruptedException {
     return delegate().pollLast(timeout, unit);
   }
@@ -116,6 +120,7 @@ public E take() throws InterruptedException {
   }
 
   @Override
+  @CheckForNull
   public E poll(long timeout, TimeUnit unit) throws InterruptedException {
     return delegate().poll(timeout, unit);
   }
diff --git a/android/guava/src/com/google/common/collect/ForwardingCollection.java b/android/guava/src/com/google/common/collect/ForwardingCollection.java
index 416ff968a715..ca1edc118303 100644
--- a/android/guava/src/com/google/common/collect/ForwardingCollection.java
+++ b/android/guava/src/com/google/common/collect/ForwardingCollection.java
@@ -21,7 +21,8 @@
 import com.google.errorprone.annotations.CanIgnoreReturnValue;
 import java.util.Collection;
 import java.util.Iterator;
-import org.checkerframework.checker.nullness.compatqual.NullableDecl;
+import javax.annotation.CheckForNull;
+import org.checkerframework.checker.nullness.qual.Nullable;
 
 /**
  * A collection which forwards all its method calls to another collection. Subclasses should
@@ -46,7 +47,9 @@
  * @since 2.0
  */
 @GwtCompatible
-public abstract class ForwardingCollection<E> extends ForwardingObject implements Collection<E> {
+@ElementTypesAreNonnullByDefault
+public abstract class ForwardingCollection<E extends @Nullable Object> extends ForwardingObject
+    implements Collection<E> {
   // TODO(lowasser): identify places where thread safety is actually lost
 
   /** Constructor for use by subclasses. */
@@ -77,19 +80,19 @@ public boolean isEmpty() {
   }
 
   @Override
-  public boolean contains(Object object) {
+  public boolean contains(@CheckForNull Object object) {
     return delegate().contains(object);
   }
 
   @CanIgnoreReturnValue
   @Override
-  public boolean add(E element) {
+  public boolean add(@ParametricNullness E element) {
     return delegate().add(element);
   }
 
   @CanIgnoreReturnValue
   @Override
-  public boolean remove(Object object) {
+  public boolean remove(@CheckForNull Object object) {
     return delegate().remove(object);
   }
 
@@ -116,13 +119,14 @@ public void clear() {
   }
 
   @Override
-  public Object[] toArray() {
+  public @Nullable Object[] toArray() {
     return delegate().toArray();
   }
 
   @CanIgnoreReturnValue
   @Override
-  public <T> T[] toArray(T[] array) {
+  @SuppressWarnings("nullness") // b/192354773 in our checker affects toArray declarations
+  public <T extends @Nullable Object> T[] toArray(T[] array) {
     return delegate().toArray(array);
   }
 
@@ -133,7 +137,7 @@ public <T> T[] toArray(T[] array) {
    *
    * @since 7.0
    */
-  protected boolean standardContains(@NullableDecl Object object) {
+  protected boolean standardContains(@CheckForNull Object object) {
     return Iterators.contains(iterator(), object);
   }
 
@@ -165,7 +169,7 @@ protected boolean standardAddAll(Collection<? extends E> collection) {
    *
    * @since 7.0
    */
-  protected boolean standardRemove(@NullableDecl Object object) {
+  protected boolean standardRemove(@CheckForNull Object object) {
     Iterator<E> iterator = iterator();
     while (iterator.hasNext()) {
       if (Objects.equal(iterator.next(), object)) {
@@ -238,8 +242,8 @@ protected String standardToString() {
    *
    * @since 7.0
    */
-  protected Object[] standardToArray() {
-    Object[] newArray = new Object[size()];
+  protected @Nullable Object[] standardToArray() {
+    @Nullable Object[] newArray = new @Nullable Object[size()];
     return toArray(newArray);
   }
 
@@ -250,7 +254,7 @@ protected Object[] standardToArray() {
    *
    * @since 7.0
    */
-  protected <T> T[] standardToArray(T[] array) {
+  protected <T extends @Nullable Object> T[] standardToArray(T[] array) {
     return ObjectArrays.toArrayImpl(this, array);
   }
 }
diff --git a/android/guava/src/com/google/common/collect/ForwardingConcurrentMap.java b/android/guava/src/com/google/common/collect/ForwardingConcurrentMap.java
index 0910424b7e58..b662b0774a0f 100644
--- a/android/guava/src/com/google/common/collect/ForwardingConcurrentMap.java
+++ b/android/guava/src/com/google/common/collect/ForwardingConcurrentMap.java
@@ -19,6 +19,7 @@
 import com.google.common.annotations.GwtCompatible;
 import com.google.errorprone.annotations.CanIgnoreReturnValue;
 import java.util.concurrent.ConcurrentMap;
+import javax.annotation.CheckForNull;
 
 /**
  * A concurrent map which forwards all its method calls to another concurrent map. Subclasses should
@@ -36,6 +37,7 @@
  * @since 2.0
  */
 @GwtCompatible
+@ElementTypesAreNonnullByDefault
 public abstract class ForwardingConcurrentMap<K, V> extends ForwardingMap<K, V>
     implements ConcurrentMap<K, V> {
 
@@ -47,18 +49,20 @@ protected ForwardingConcurrentMap() {}
 
   @CanIgnoreReturnValue
   @Override
+  @CheckForNull
   public V putIfAbsent(K key, V value) {
     return delegate().putIfAbsent(key, value);
   }
 
   @CanIgnoreReturnValue
   @Override
-  public boolean remove(Object key, Object value) {
+  public boolean remove(@CheckForNull Object key, @CheckForNull Object value) {
     return delegate().remove(key, value);
   }
 
   @CanIgnoreReturnValue
   @Override
+  @CheckForNull
   public V replace(K key, V value) {
     return delegate().replace(key, value);
   }
diff --git a/android/guava/src/com/google/common/collect/ForwardingDeque.java b/android/guava/src/com/google/common/collect/ForwardingDeque.java
index 87ac71bd67ec..571535cab917 100644
--- a/android/guava/src/com/google/common/collect/ForwardingDeque.java
+++ b/android/guava/src/com/google/common/collect/ForwardingDeque.java
@@ -20,6 +20,8 @@
 import com.google.errorprone.annotations.CanIgnoreReturnValue;
 import java.util.Deque;
 import java.util.Iterator;
+import javax.annotation.CheckForNull;
+import org.checkerframework.checker.nullness.qual.Nullable;
 
 /**
  * A deque which forwards all its method calls to another deque. Subclasses should override one or
@@ -39,7 +41,9 @@
  * @since 12.0
  */
 @GwtIncompatible
-public abstract class ForwardingDeque<E> extends ForwardingQueue<E> implements Deque<E> {
+@ElementTypesAreNonnullByDefault
+public abstract class ForwardingDeque<E extends @Nullable Object> extends ForwardingQueue<E>
+    implements Deque<E> {
 
   /** Constructor for use by subclasses. */
   protected ForwardingDeque() {}
@@ -48,12 +52,12 @@ protected ForwardingDeque() {}
   protected abstract Deque<E> delegate();
 
   @Override
-  public void addFirst(E e) {
+  public void addFirst(@ParametricNullness E e) {
     delegate().addFirst(e);
   }
 
   @Override
-  public void addLast(E e) {
+  public void addLast(@ParametricNullness E e) {
     delegate().addLast(e);
   }
 
@@ -63,81 +67,90 @@ public Iterator<E> descendingIterator() {
   }
 
   @Override
+  @ParametricNullness
   public E getFirst() {
     return delegate().getFirst();
   }
 
   @Override
+  @ParametricNullness
   public E getLast() {
     return delegate().getLast();
   }
 
   @CanIgnoreReturnValue // TODO(cpovirk): Consider removing this?
   @Override
-  public boolean offerFirst(E e) {
+  public boolean offerFirst(@ParametricNullness E e) {
     return delegate().offerFirst(e);
   }
 
   @CanIgnoreReturnValue // TODO(cpovirk): Consider removing this?
   @Override
-  public boolean offerLast(E e) {
+  public boolean offerLast(@ParametricNullness E e) {
     return delegate().offerLast(e);
   }
 
   @Override
+  @CheckForNull
   public E peekFirst() {
     return delegate().peekFirst();
   }
 
   @Override
+  @CheckForNull
   public E peekLast() {
     return delegate().peekLast();
   }
 
   @CanIgnoreReturnValue // TODO(cpovirk): Consider removing this?
   @Override
+  @CheckForNull
   public E pollFirst() {
     return delegate().pollFirst();
   }
 
   @CanIgnoreReturnValue // TODO(cpovirk): Consider removing this?
   @Override
+  @CheckForNull
   public E pollLast() {
     return delegate().pollLast();
   }
 
   @CanIgnoreReturnValue
   @Override
+  @ParametricNullness
   public E pop() {
     return delegate().pop();
   }
 
   @Override
-  public void push(E e) {
+  public void push(@ParametricNullness E e) {
     delegate().push(e);
   }
 
   @CanIgnoreReturnValue
   @Override
+  @ParametricNullness
   public E removeFirst() {
     return delegate().removeFirst();
   }
 
   @CanIgnoreReturnValue
   @Override
+  @ParametricNullness
   public E removeLast() {
     return delegate().removeLast();
   }
 
   @CanIgnoreReturnValue
   @Override
-  public boolean removeFirstOccurrence(Object o) {
+  public boolean removeFirstOccurrence(@CheckForNull Object o) {
     return delegate().removeFirstOccurrence(o);
   }
 
   @CanIgnoreReturnValue
   @Override
-  public boolean removeLastOccurrence(Object o) {
+  public boolean removeLastOccurrence(@CheckForNull Object o) {
     return delegate().removeLastOccurrence(o);
   }
 }
diff --git a/android/guava/src/com/google/common/collect/ForwardingImmutableCollection.java b/android/guava/src/com/google/common/collect/ForwardingImmutableCollection.java
index c0b9c5e54d74..043fe5863593 100644
--- a/android/guava/src/com/google/common/collect/ForwardingImmutableCollection.java
+++ b/android/guava/src/com/google/common/collect/ForwardingImmutableCollection.java
@@ -24,6 +24,7 @@
  * @author Hayward Chan
  */
 @GwtCompatible(emulated = true)
+@ElementTypesAreNonnullByDefault
 class ForwardingImmutableCollection {
   private ForwardingImmutableCollection() {}
 }
diff --git a/android/guava/src/com/google/common/collect/ForwardingImmutableList.java b/android/guava/src/com/google/common/collect/ForwardingImmutableList.java
index 2b9092ea4c93..bd5480d589c4 100644
--- a/android/guava/src/com/google/common/collect/ForwardingImmutableList.java
+++ b/android/guava/src/com/google/common/collect/ForwardingImmutableList.java
@@ -24,6 +24,7 @@
  * @author Chris Povirk
  */
 @GwtCompatible(emulated = true)
+@ElementTypesAreNonnullByDefault
 abstract class ForwardingImmutableList<E> {
   private ForwardingImmutableList() {}
 }
diff --git a/android/guava/src/com/google/common/collect/ForwardingImmutableMap.java b/android/guava/src/com/google/common/collect/ForwardingImmutableMap.java
index a36715743f0a..22cc9ff8711c 100644
--- a/android/guava/src/com/google/common/collect/ForwardingImmutableMap.java
+++ b/android/guava/src/com/google/common/collect/ForwardingImmutableMap.java
@@ -24,6 +24,7 @@
  * @author Chris Povirk
  */
 @GwtCompatible(emulated = true)
+@ElementTypesAreNonnullByDefault
 abstract class ForwardingImmutableMap<K, V> {
   private ForwardingImmutableMap() {}
 }
diff --git a/android/guava/src/com/google/common/collect/ForwardingImmutableSet.java b/android/guava/src/com/google/common/collect/ForwardingImmutableSet.java
index c7d7bf6d778b..047d5fd32216 100644
--- a/android/guava/src/com/google/common/collect/ForwardingImmutableSet.java
+++ b/android/guava/src/com/google/common/collect/ForwardingImmutableSet.java
@@ -24,6 +24,7 @@
  * @author Chris Povirk
  */
 @GwtCompatible(emulated = true)
+@ElementTypesAreNonnullByDefault
 abstract class ForwardingImmutableSet<E> {
   private ForwardingImmutableSet() {}
 }
diff --git a/android/guava/src/com/google/common/collect/ForwardingIterator.java b/android/guava/src/com/google/common/collect/ForwardingIterator.java
index 5ecd3d293126..1f5a8f110eaf 100644
--- a/android/guava/src/com/google/common/collect/ForwardingIterator.java
+++ b/android/guava/src/com/google/common/collect/ForwardingIterator.java
@@ -19,6 +19,7 @@
 import com.google.common.annotations.GwtCompatible;
 import com.google.errorprone.annotations.CanIgnoreReturnValue;
 import java.util.Iterator;
+import org.checkerframework.checker.nullness.qual.Nullable;
 
 /**
  * An iterator which forwards all its method calls to another iterator. Subclasses should override
@@ -36,7 +37,9 @@
  * @since 2.0
  */
 @GwtCompatible
-public abstract class ForwardingIterator<T> extends ForwardingObject implements Iterator<T> {
+@ElementTypesAreNonnullByDefault
+public abstract class ForwardingIterator<T extends @Nullable Object> extends ForwardingObject
+    implements Iterator<T> {
 
   /** Constructor for use by subclasses. */
   protected ForwardingIterator() {}
@@ -51,6 +54,7 @@ public boolean hasNext() {
 
   @CanIgnoreReturnValue
   @Override
+  @ParametricNullness
   public T next() {
     return delegate().next();
   }
diff --git a/android/guava/src/com/google/common/collect/ForwardingList.java b/android/guava/src/com/google/common/collect/ForwardingList.java
index bfd208313410..4b4551e5e367 100644
--- a/android/guava/src/com/google/common/collect/ForwardingList.java
+++ b/android/guava/src/com/google/common/collect/ForwardingList.java
@@ -23,7 +23,8 @@
 import java.util.Iterator;
 import java.util.List;
 import java.util.ListIterator;
-import org.checkerframework.checker.nullness.compatqual.NullableDecl;
+import javax.annotation.CheckForNull;
+import org.checkerframework.checker.nullness.qual.Nullable;
 
 /**
  * A list which forwards all its method calls to another list. Subclasses should override one or
@@ -51,7 +52,9 @@
  * @since 2.0
  */
 @GwtCompatible
-public abstract class ForwardingList<E> extends ForwardingCollection<E> implements List<E> {
+@ElementTypesAreNonnullByDefault
+public abstract class ForwardingList<E extends @Nullable Object> extends ForwardingCollection<E>
+    implements List<E> {
   // TODO(lowasser): identify places where thread safety is actually lost
 
   /** Constructor for use by subclasses. */
@@ -61,7 +64,7 @@ protected ForwardingList() {}
   protected abstract List<E> delegate();
 
   @Override
-  public void add(int index, E element) {
+  public void add(int index, @ParametricNullness E element) {
     delegate().add(index, element);
   }
 
@@ -72,17 +75,18 @@ public boolean addAll(int index, Collection<? extends E> elements) {
   }
 
   @Override
+  @ParametricNullness
   public E get(int index) {
     return delegate().get(index);
   }
 
   @Override
-  public int indexOf(Object element) {
+  public int indexOf(@CheckForNull Object element) {
     return delegate().indexOf(element);
   }
 
   @Override
-  public int lastIndexOf(Object element) {
+  public int lastIndexOf(@CheckForNull Object element) {
     return delegate().lastIndexOf(element);
   }
 
@@ -98,13 +102,15 @@ public ListIterator<E> listIterator(int index) {
 
   @CanIgnoreReturnValue
   @Override
+  @ParametricNullness
   public E remove(int index) {
     return delegate().remove(index);
   }
 
   @CanIgnoreReturnValue
   @Override
-  public E set(int index, E element) {
+  @ParametricNullness
+  public E set(int index, @ParametricNullness E element) {
     return delegate().set(index, element);
   }
 
@@ -114,7 +120,7 @@ public List<E> subList(int fromIndex, int toIndex) {
   }
 
   @Override
-  public boolean equals(@NullableDecl Object object) {
+  public boolean equals(@CheckForNull Object object) {
     return object == this || delegate().equals(object);
   }
 
@@ -130,7 +136,7 @@ public int hashCode() {
    *
    * @since 7.0
    */
-  protected boolean standardAdd(E element) {
+  protected boolean standardAdd(@ParametricNullness E element) {
     add(size(), element);
     return true;
   }
@@ -153,7 +159,7 @@ protected boolean standardAddAll(int index, Iterable<? extends E> elements) {
    *
    * @since 7.0
    */
-  protected int standardIndexOf(@NullableDecl Object element) {
+  protected int standardIndexOf(@CheckForNull Object element) {
     return Lists.indexOfImpl(this, element);
   }
 
@@ -164,7 +170,7 @@ protected int standardIndexOf(@NullableDecl Object element) {
    *
    * @since 7.0
    */
-  protected int standardLastIndexOf(@NullableDecl Object element) {
+  protected int standardLastIndexOf(@CheckForNull Object element) {
     return Lists.lastIndexOfImpl(this, element);
   }
 
@@ -222,7 +228,7 @@ protected List<E> standardSubList(int fromIndex, int toIndex) {
    * @since 7.0
    */
   @Beta
-  protected boolean standardEquals(@NullableDecl Object object) {
+  protected boolean standardEquals(@CheckForNull Object object) {
     return Lists.equalsImpl(this, object);
   }
 
diff --git a/android/guava/src/com/google/common/collect/ForwardingListIterator.java b/android/guava/src/com/google/common/collect/ForwardingListIterator.java
index bc2a5ad4ff58..a2ac32b6fad9 100644
--- a/android/guava/src/com/google/common/collect/ForwardingListIterator.java
+++ b/android/guava/src/com/google/common/collect/ForwardingListIterator.java
@@ -19,6 +19,7 @@
 import com.google.common.annotations.GwtCompatible;
 import com.google.errorprone.annotations.CanIgnoreReturnValue;
 import java.util.ListIterator;
+import org.checkerframework.checker.nullness.qual.Nullable;
 
 /**
  * A list iterator which forwards all its method calls to another list iterator. Subclasses should
@@ -36,8 +37,9 @@
  * @since 2.0
  */
 @GwtCompatible
-public abstract class ForwardingListIterator<E> extends ForwardingIterator<E>
-    implements ListIterator<E> {
+@ElementTypesAreNonnullByDefault
+public abstract class ForwardingListIterator<E extends @Nullable Object>
+    extends ForwardingIterator<E> implements ListIterator<E> {
 
   /** Constructor for use by subclasses. */
   protected ForwardingListIterator() {}
@@ -46,7 +48,7 @@ protected ForwardingListIterator() {}
   protected abstract ListIterator<E> delegate();
 
   @Override
-  public void add(E element) {
+  public void add(@ParametricNullness E element) {
     delegate().add(element);
   }
 
@@ -62,6 +64,7 @@ public int nextIndex() {
 
   @CanIgnoreReturnValue
   @Override
+  @ParametricNullness
   public E previous() {
     return delegate().previous();
   }
@@ -72,7 +75,7 @@ public int previousIndex() {
   }
 
   @Override
-  public void set(E element) {
+  public void set(@ParametricNullness E element) {
     delegate().set(element);
   }
 }
diff --git a/android/guava/src/com/google/common/collect/ForwardingListMultimap.java b/android/guava/src/com/google/common/collect/ForwardingListMultimap.java
index 8cf3d703b483..11779c0bb826 100644
--- a/android/guava/src/com/google/common/collect/ForwardingListMultimap.java
+++ b/android/guava/src/com/google/common/collect/ForwardingListMultimap.java
@@ -19,7 +19,8 @@
 import com.google.common.annotations.GwtCompatible;
 import com.google.errorprone.annotations.CanIgnoreReturnValue;
 import java.util.List;
-import org.checkerframework.checker.nullness.compatqual.NullableDecl;
+import javax.annotation.CheckForNull;
+import org.checkerframework.checker.nullness.qual.Nullable;
 
 /**
  * A list multimap which forwards all its method calls to another list multimap. Subclasses should
@@ -34,8 +35,9 @@
  * @since 3.0
  */
 @GwtCompatible
-public abstract class ForwardingListMultimap<K, V> extends ForwardingMultimap<K, V>
-    implements ListMultimap<K, V> {
+@ElementTypesAreNonnullByDefault
+public abstract class ForwardingListMultimap<K extends @Nullable Object, V extends @Nullable Object>
+    extends ForwardingMultimap<K, V> implements ListMultimap<K, V> {
 
   /** Constructor for use by subclasses. */
   protected ForwardingListMultimap() {}
@@ -44,19 +46,19 @@ protected ForwardingListMultimap() {}
   protected abstract ListMultimap<K, V> delegate();
 
   @Override
-  public List<V> get(@NullableDecl K key) {
+  public List<V> get(@ParametricNullness K key) {
     return delegate().get(key);
   }
 
   @CanIgnoreReturnValue
   @Override
-  public List<V> removeAll(@NullableDecl Object key) {
+  public List<V> removeAll(@CheckForNull Object key) {
     return delegate().removeAll(key);
   }
 
   @CanIgnoreReturnValue
   @Override
-  public List<V> replaceValues(K key, Iterable<? extends V> values) {
+  public List<V> replaceValues(@ParametricNullness K key, Iterable<? extends V> values) {
     return delegate().replaceValues(key, values);
   }
 }
diff --git a/android/guava/src/com/google/common/collect/ForwardingMap.java b/android/guava/src/com/google/common/collect/ForwardingMap.java
index 4032bf9e6190..315a4fabca3d 100644
--- a/android/guava/src/com/google/common/collect/ForwardingMap.java
+++ b/android/guava/src/com/google/common/collect/ForwardingMap.java
@@ -24,7 +24,8 @@
 import java.util.Iterator;
 import java.util.Map;
 import java.util.Set;
-import org.checkerframework.checker.nullness.compatqual.NullableDecl;
+import javax.annotation.CheckForNull;
+import org.checkerframework.checker.nullness.qual.Nullable;
 
 /**
  * A map which forwards all its method calls to another map. Subclasses should override one or more
@@ -55,7 +56,9 @@
  * @since 2.0
  */
 @GwtCompatible
-public abstract class ForwardingMap<K, V> extends ForwardingObject implements Map<K, V> {
+@ElementTypesAreNonnullByDefault
+public abstract class ForwardingMap<K extends @Nullable Object, V extends @Nullable Object>
+    extends ForwardingObject implements Map<K, V> {
   // TODO(lowasser): identify places where thread safety is actually lost
 
   /** Constructor for use by subclasses. */
@@ -76,7 +79,8 @@ public boolean isEmpty() {
 
   @CanIgnoreReturnValue
   @Override
-  public V remove(Object key) {
+  @CheckForNull
+  public V remove(@CheckForNull Object key) {
     return delegate().remove(key);
   }
 
@@ -86,23 +90,25 @@ public void clear() {
   }
 
   @Override
-  public boolean containsKey(@NullableDecl Object key) {
+  public boolean containsKey(@CheckForNull Object key) {
     return delegate().containsKey(key);
   }
 
   @Override
-  public boolean containsValue(@NullableDecl Object value) {
+  public boolean containsValue(@CheckForNull Object value) {
     return delegate().containsValue(value);
   }
 
   @Override
-  public V get(@NullableDecl Object key) {
+  @CheckForNull
+  public V get(@CheckForNull Object key) {
     return delegate().get(key);
   }
 
   @CanIgnoreReturnValue
   @Override
-  public V put(K key, V value) {
+  @CheckForNull
+  public V put(@ParametricNullness K key, @ParametricNullness V value) {
     return delegate().put(key, value);
   }
 
@@ -127,7 +133,7 @@ public Set<Entry<K, V>> entrySet() {
   }
 
   @Override
-  public boolean equals(@NullableDecl Object object) {
+  public boolean equals(@CheckForNull Object object) {
     return object == this || delegate().equals(object);
   }
 
@@ -158,7 +164,8 @@ protected void standardPutAll(Map<? extends K, ? extends V> map) {
    * @since 7.0
    */
   @Beta
-  protected V standardRemove(@NullableDecl Object key) {
+  @CheckForNull
+  protected V standardRemove(@CheckForNull Object key) {
     Iterator<Entry<K, V>> entryIterator = entrySet().iterator();
     while (entryIterator.hasNext()) {
       Entry<K, V> entry = entryIterator.next();
@@ -207,7 +214,7 @@ public StandardKeySet() {
    * @since 7.0
    */
   @Beta
-  protected boolean standardContainsKey(@NullableDecl Object key) {
+  protected boolean standardContainsKey(@CheckForNull Object key) {
     return Maps.containsKeyImpl(this, key);
   }
 
@@ -235,7 +242,7 @@ public StandardValues() {
    *
    * @since 7.0
    */
-  protected boolean standardContainsValue(@NullableDecl Object value) {
+  protected boolean standardContainsValue(@CheckForNull Object value) {
     return Maps.containsValueImpl(this, value);
   }
 
@@ -277,7 +284,7 @@ protected boolean standardIsEmpty() {
    *
    * @since 7.0
    */
-  protected boolean standardEquals(@NullableDecl Object object) {
+  protected boolean standardEquals(@CheckForNull Object object) {
     return Maps.equalsImpl(this, object);
   }
 
diff --git a/android/guava/src/com/google/common/collect/ForwardingMapEntry.java b/android/guava/src/com/google/common/collect/ForwardingMapEntry.java
index 198b94bd5506..6816ccbbefce 100644
--- a/android/guava/src/com/google/common/collect/ForwardingMapEntry.java
+++ b/android/guava/src/com/google/common/collect/ForwardingMapEntry.java
@@ -21,7 +21,8 @@
 import com.google.common.base.Objects;
 import java.util.Map;
 import java.util.Map.Entry;
-import org.checkerframework.checker.nullness.compatqual.NullableDecl;
+import javax.annotation.CheckForNull;
+import org.checkerframework.checker.nullness.qual.Nullable;
 
 /**
  * A map entry which forwards all its method calls to another map entry. Subclasses should override
@@ -47,7 +48,9 @@
  * @since 2.0
  */
 @GwtCompatible
-public abstract class ForwardingMapEntry<K, V> extends ForwardingObject implements Map.Entry<K, V> {
+@ElementTypesAreNonnullByDefault
+public abstract class ForwardingMapEntry<K extends @Nullable Object, V extends @Nullable Object>
+    extends ForwardingObject implements Map.Entry<K, V> {
   // TODO(lowasser): identify places where thread safety is actually lost
 
   /** Constructor for use by subclasses. */
@@ -57,22 +60,25 @@ protected ForwardingMapEntry() {}
   protected abstract Entry<K, V> delegate();
 
   @Override
+  @ParametricNullness
   public K getKey() {
     return delegate().getKey();
   }
 
   @Override
+  @ParametricNullness
   public V getValue() {
     return delegate().getValue();
   }
 
   @Override
-  public V setValue(V value) {
+  @ParametricNullness
+  public V setValue(@ParametricNullness V value) {
     return delegate().setValue(value);
   }
 
   @Override
-  public boolean equals(@NullableDecl Object object) {
+  public boolean equals(@CheckForNull Object object) {
     return delegate().equals(object);
   }
 
@@ -88,7 +94,7 @@ public int hashCode() {
    *
    * @since 7.0
    */
-  protected boolean standardEquals(@NullableDecl Object object) {
+  protected boolean standardEquals(@CheckForNull Object object) {
     if (object instanceof Entry) {
       Entry<?, ?> that = (Entry<?, ?>) object;
       return Objects.equal(this.getKey(), that.getKey())
diff --git a/android/guava/src/com/google/common/collect/ForwardingMultimap.java b/android/guava/src/com/google/common/collect/ForwardingMultimap.java
index 991d0cf9a089..a3db0618ed80 100644
--- a/android/guava/src/com/google/common/collect/ForwardingMultimap.java
+++ b/android/guava/src/com/google/common/collect/ForwardingMultimap.java
@@ -22,7 +22,8 @@
 import java.util.Map;
 import java.util.Map.Entry;
 import java.util.Set;
-import org.checkerframework.checker.nullness.compatqual.NullableDecl;
+import javax.annotation.CheckForNull;
+import org.checkerframework.checker.nullness.qual.Nullable;
 
 /**
  * A multimap which forwards all its method calls to another multimap. Subclasses should override
@@ -37,7 +38,9 @@
  * @since 2.0
  */
 @GwtCompatible
-public abstract class ForwardingMultimap<K, V> extends ForwardingObject implements Multimap<K, V> {
+@ElementTypesAreNonnullByDefault
+public abstract class ForwardingMultimap<K extends @Nullable Object, V extends @Nullable Object>
+    extends ForwardingObject implements Multimap<K, V> {
 
   /** Constructor for use by subclasses. */
   protected ForwardingMultimap() {}
@@ -56,17 +59,17 @@ public void clear() {
   }
 
   @Override
-  public boolean containsEntry(@NullableDecl Object key, @NullableDecl Object value) {
+  public boolean containsEntry(@CheckForNull Object key, @CheckForNull Object value) {
     return delegate().containsEntry(key, value);
   }
 
   @Override
-  public boolean containsKey(@NullableDecl Object key) {
+  public boolean containsKey(@CheckForNull Object key) {
     return delegate().containsKey(key);
   }
 
   @Override
-  public boolean containsValue(@NullableDecl Object value) {
+  public boolean containsValue(@CheckForNull Object value) {
     return delegate().containsValue(value);
   }
 
@@ -76,7 +79,7 @@ public Collection<Entry<K, V>> entries() {
   }
 
   @Override
-  public Collection<V> get(@NullableDecl K key) {
+  public Collection<V> get(@ParametricNullness K key) {
     return delegate().get(key);
   }
 
@@ -97,13 +100,13 @@ public Set<K> keySet() {
 
   @CanIgnoreReturnValue
   @Override
-  public boolean put(K key, V value) {
+  public boolean put(@ParametricNullness K key, @ParametricNullness V value) {
     return delegate().put(key, value);
   }
 
   @CanIgnoreReturnValue
   @Override
-  public boolean putAll(K key, Iterable<? extends V> values) {
+  public boolean putAll(@ParametricNullness K key, Iterable<? extends V> values) {
     return delegate().putAll(key, values);
   }
 
@@ -115,19 +118,19 @@ public boolean putAll(Multimap<? extends K, ? extends V> multimap) {
 
   @CanIgnoreReturnValue
   @Override
-  public boolean remove(@NullableDecl Object key, @NullableDecl Object value) {
+  public boolean remove(@CheckForNull Object key, @CheckForNull Object value) {
     return delegate().remove(key, value);
   }
 
   @CanIgnoreReturnValue
   @Override
-  public Collection<V> removeAll(@NullableDecl Object key) {
+  public Collection<V> removeAll(@CheckForNull Object key) {
     return delegate().removeAll(key);
   }
 
   @CanIgnoreReturnValue
   @Override
-  public Collection<V> replaceValues(K key, Iterable<? extends V> values) {
+  public Collection<V> replaceValues(@ParametricNullness K key, Iterable<? extends V> values) {
     return delegate().replaceValues(key, values);
   }
 
@@ -142,7 +145,7 @@ public Collection<V> values() {
   }
 
   @Override
-  public boolean equals(@NullableDecl Object object) {
+  public boolean equals(@CheckForNull Object object) {
     return object == this || delegate().equals(object);
   }
 
diff --git a/android/guava/src/com/google/common/collect/ForwardingMultiset.java b/android/guava/src/com/google/common/collect/ForwardingMultiset.java
index 9a7084f54950..857b9aec7bbe 100644
--- a/android/guava/src/com/google/common/collect/ForwardingMultiset.java
+++ b/android/guava/src/com/google/common/collect/ForwardingMultiset.java
@@ -23,7 +23,8 @@
 import java.util.Collection;
 import java.util.Iterator;
 import java.util.Set;
-import org.checkerframework.checker.nullness.compatqual.NullableDecl;
+import javax.annotation.CheckForNull;
+import org.checkerframework.checker.nullness.qual.Nullable;
 
 /**
  * A multiset which forwards all its method calls to another multiset. Subclasses should override
@@ -48,7 +49,9 @@
  * @since 2.0
  */
 @GwtCompatible
-public abstract class ForwardingMultiset<E> extends ForwardingCollection<E> implements Multiset<E> {
+@ElementTypesAreNonnullByDefault
+public abstract class ForwardingMultiset<E extends @Nullable Object> extends ForwardingCollection<E>
+    implements Multiset<E> {
 
   /** Constructor for use by subclasses. */
   protected ForwardingMultiset() {}
@@ -57,19 +60,19 @@ protected ForwardingMultiset() {}
   protected abstract Multiset<E> delegate();
 
   @Override
-  public int count(Object element) {
+  public int count(@CheckForNull Object element) {
     return delegate().count(element);
   }
 
   @CanIgnoreReturnValue
   @Override
-  public int add(E element, int occurrences) {
+  public int add(@ParametricNullness E element, int occurrences) {
     return delegate().add(element, occurrences);
   }
 
   @CanIgnoreReturnValue
   @Override
-  public int remove(Object element, int occurrences) {
+  public int remove(@CheckForNull Object element, int occurrences) {
     return delegate().remove(element, occurrences);
   }
 
@@ -84,7 +87,7 @@ public Set<Entry<E>> entrySet() {
   }
 
   @Override
-  public boolean equals(@NullableDecl Object object) {
+  public boolean equals(@CheckForNull Object object) {
     return object == this || delegate().equals(object);
   }
 
@@ -95,13 +98,13 @@ public int hashCode() {
 
   @CanIgnoreReturnValue
   @Override
-  public int setCount(E element, int count) {
+  public int setCount(@ParametricNullness E element, int count) {
     return delegate().setCount(element, count);
   }
 
   @CanIgnoreReturnValue
   @Override
-  public boolean setCount(E element, int oldCount, int newCount) {
+  public boolean setCount(@ParametricNullness E element, int oldCount, int newCount) {
     return delegate().setCount(element, oldCount, newCount);
   }
 
@@ -112,7 +115,7 @@ public boolean setCount(E element, int oldCount, int newCount) {
    * @since 7.0
    */
   @Override
-  protected boolean standardContains(@NullableDecl Object object) {
+  protected boolean standardContains(@CheckForNull Object object) {
     return count(object) > 0;
   }
 
@@ -136,7 +139,7 @@ protected void standardClear() {
    * @since 7.0
    */
   @Beta
-  protected int standardCount(@NullableDecl Object object) {
+  protected int standardCount(@CheckForNull Object object) {
     for (Entry<?> entry : this.entrySet()) {
       if (Objects.equal(entry.getElement(), object)) {
         return entry.getCount();
@@ -152,7 +155,7 @@ protected int standardCount(@NullableDecl Object object) {
    *
    * @since 7.0
    */
-  protected boolean standardAdd(E element) {
+  protected boolean standardAdd(@ParametricNullness E element) {
     add(element, 1);
     return true;
   }
@@ -178,7 +181,7 @@ protected boolean standardAddAll(Collection<? extends E> elementsToAdd) {
    * @since 7.0
    */
   @Override
-  protected boolean standardRemove(Object element) {
+  protected boolean standardRemove(@CheckForNull Object element) {
     return remove(element, 1) > 0;
   }
 
@@ -214,7 +217,7 @@ protected boolean standardRetainAll(Collection<?> elementsToRetain) {
    *
    * @since 7.0
    */
-  protected int standardSetCount(E element, int count) {
+  protected int standardSetCount(@ParametricNullness E element, int count) {
     return Multisets.setCountImpl(this, element, count);
   }
 
@@ -225,7 +228,7 @@ protected int standardSetCount(E element, int count) {
    *
    * @since 7.0
    */
-  protected boolean standardSetCount(E element, int oldCount, int newCount) {
+  protected boolean standardSetCount(@ParametricNullness E element, int oldCount, int newCount) {
     return Multisets.setCountImpl(this, element, oldCount, newCount);
   }
 
@@ -285,7 +288,7 @@ protected int standardSize() {
    *
    * @since 7.0
    */
-  protected boolean standardEquals(@NullableDecl Object object) {
+  protected boolean standardEquals(@CheckForNull Object object) {
     return Multisets.equalsImpl(this, object);
   }
 
diff --git a/android/guava/src/com/google/common/collect/ForwardingNavigableMap.java b/android/guava/src/com/google/common/collect/ForwardingNavigableMap.java
index c8d0fd54b62d..e0e1c39e8ef3 100644
--- a/android/guava/src/com/google/common/collect/ForwardingNavigableMap.java
+++ b/android/guava/src/com/google/common/collect/ForwardingNavigableMap.java
@@ -16,7 +16,6 @@
 
 package com.google.common.collect;
 
-import static com.google.common.collect.CollectPreconditions.checkRemove;
 import static com.google.common.collect.Maps.keyOrNull;
 
 import com.google.common.annotations.Beta;
@@ -26,6 +25,8 @@
 import java.util.NavigableSet;
 import java.util.NoSuchElementException;
 import java.util.SortedMap;
+import javax.annotation.CheckForNull;
+import org.checkerframework.checker.nullness.qual.Nullable;
 
 /**
  * A navigable map which forwards all its method calls to another navigable map. Subclasses should
@@ -54,8 +55,9 @@
  * @since 12.0
  */
 @GwtIncompatible
-public abstract class ForwardingNavigableMap<K, V> extends ForwardingSortedMap<K, V>
-    implements NavigableMap<K, V> {
+@ElementTypesAreNonnullByDefault
+public abstract class ForwardingNavigableMap<K extends @Nullable Object, V extends @Nullable Object>
+    extends ForwardingSortedMap<K, V> implements NavigableMap<K, V> {
 
   /** Constructor for use by subclasses. */
   protected ForwardingNavigableMap() {}
@@ -64,7 +66,8 @@ protected ForwardingNavigableMap() {}
   protected abstract NavigableMap<K, V> delegate();
 
   @Override
-  public Entry<K, V> lowerEntry(K key) {
+  @CheckForNull
+  public Entry<K, V> lowerEntry(@ParametricNullness K key) {
     return delegate().lowerEntry(key);
   }
 
@@ -73,12 +76,14 @@ public Entry<K, V> lowerEntry(K key) {
    * #headMap(Object, boolean)}. If you override {@code headMap}, you may wish to override {@code
    * lowerEntry} to forward to this implementation.
    */
-  protected Entry<K, V> standardLowerEntry(K key) {
+  @CheckForNull
+  protected Entry<K, V> standardLowerEntry(@ParametricNullness K key) {
     return headMap(key, false).lastEntry();
   }
 
   @Override
-  public K lowerKey(K key) {
+  @CheckForNull
+  public K lowerKey(@ParametricNullness K key) {
     return delegate().lowerKey(key);
   }
 
@@ -87,12 +92,14 @@ public K lowerKey(K key) {
    * {@link #lowerEntry}, you may wish to override {@code lowerKey} to forward to this
    * implementation.
    */
-  protected K standardLowerKey(K key) {
+  @CheckForNull
+  protected K standardLowerKey(@ParametricNullness K key) {
     return keyOrNull(lowerEntry(key));
   }
 
   @Override
-  public Entry<K, V> floorEntry(K key) {
+  @CheckForNull
+  public Entry<K, V> floorEntry(@ParametricNullness K key) {
     return delegate().floorEntry(key);
   }
 
@@ -101,12 +108,14 @@ public Entry<K, V> floorEntry(K key) {
    * #headMap(Object, boolean)}. If you override {@code headMap}, you may wish to override {@code
    * floorEntry} to forward to this implementation.
    */
-  protected Entry<K, V> standardFloorEntry(K key) {
+  @CheckForNull
+  protected Entry<K, V> standardFloorEntry(@ParametricNullness K key) {
     return headMap(key, true).lastEntry();
   }
 
   @Override
-  public K floorKey(K key) {
+  @CheckForNull
+  public K floorKey(@ParametricNullness K key) {
     return delegate().floorKey(key);
   }
 
@@ -115,12 +124,14 @@ public K floorKey(K key) {
    * {@code floorEntry}, you may wish to override {@code floorKey} to forward to this
    * implementation.
    */
-  protected K standardFloorKey(K key) {
+  @CheckForNull
+  protected K standardFloorKey(@ParametricNullness K key) {
     return keyOrNull(floorEntry(key));
   }
 
   @Override
-  public Entry<K, V> ceilingEntry(K key) {
+  @CheckForNull
+  public Entry<K, V> ceilingEntry(@ParametricNullness K key) {
     return delegate().ceilingEntry(key);
   }
 
@@ -129,12 +140,14 @@ public Entry<K, V> ceilingEntry(K key) {
    * #tailMap(Object, boolean)}. If you override {@code tailMap}, you may wish to override {@code
    * ceilingEntry} to forward to this implementation.
    */
-  protected Entry<K, V> standardCeilingEntry(K key) {
+  @CheckForNull
+  protected Entry<K, V> standardCeilingEntry(@ParametricNullness K key) {
     return tailMap(key, true).firstEntry();
   }
 
   @Override
-  public K ceilingKey(K key) {
+  @CheckForNull
+  public K ceilingKey(@ParametricNullness K key) {
     return delegate().ceilingKey(key);
   }
 
@@ -143,12 +156,14 @@ public K ceilingKey(K key) {
    * {@code ceilingEntry}, you may wish to override {@code ceilingKey} to forward to this
    * implementation.
    */
-  protected K standardCeilingKey(K key) {
+  @CheckForNull
+  protected K standardCeilingKey(@ParametricNullness K key) {
     return keyOrNull(ceilingEntry(key));
   }
 
   @Override
-  public Entry<K, V> higherEntry(K key) {
+  @CheckForNull
+  public Entry<K, V> higherEntry(@ParametricNullness K key) {
     return delegate().higherEntry(key);
   }
 
@@ -157,12 +172,14 @@ public Entry<K, V> higherEntry(K key) {
    * #tailMap(Object, boolean)}. If you override {@code tailMap}, you may wish to override {@code
    * higherEntry} to forward to this implementation.
    */
-  protected Entry<K, V> standardHigherEntry(K key) {
+  @CheckForNull
+  protected Entry<K, V> standardHigherEntry(@ParametricNullness K key) {
     return tailMap(key, false).firstEntry();
   }
 
   @Override
-  public K higherKey(K key) {
+  @CheckForNull
+  public K higherKey(@ParametricNullness K key) {
     return delegate().higherKey(key);
   }
 
@@ -171,11 +188,13 @@ public K higherKey(K key) {
    * {@code higherEntry}, you may wish to override {@code higherKey} to forward to this
    * implementation.
    */
-  protected K standardHigherKey(K key) {
+  @CheckForNull
+  protected K standardHigherKey(@ParametricNullness K key) {
     return keyOrNull(higherEntry(key));
   }
 
   @Override
+  @CheckForNull
   public Entry<K, V> firstEntry() {
     return delegate().firstEntry();
   }
@@ -185,6 +204,7 @@ public Entry<K, V> firstEntry() {
    * #entrySet}. If you override {@code entrySet}, you may wish to override {@code firstEntry} to
    * forward to this implementation.
    */
+  @CheckForNull
   protected Entry<K, V> standardFirstEntry() {
     return Iterables.getFirst(entrySet(), null);
   }
@@ -204,6 +224,7 @@ protected K standardFirstKey() {
   }
 
   @Override
+  @CheckForNull
   public Entry<K, V> lastEntry() {
     return delegate().lastEntry();
   }
@@ -213,6 +234,7 @@ public Entry<K, V> lastEntry() {
    * #entrySet} of {@link #descendingMap}. If you override {@code descendingMap}, you may wish to
    * override {@code lastEntry} to forward to this implementation.
    */
+  @CheckForNull
   protected Entry<K, V> standardLastEntry() {
     return Iterables.getFirst(descendingMap().entrySet(), null);
   }
@@ -231,6 +253,7 @@ protected K standardLastKey() {
   }
 
   @Override
+  @CheckForNull
   public Entry<K, V> pollFirstEntry() {
     return delegate().pollFirstEntry();
   }
@@ -240,11 +263,13 @@ public Entry<K, V> pollFirstEntry() {
    * entrySet}. If you override {@code entrySet}, you may wish to override {@code pollFirstEntry} to
    * forward to this implementation.
    */
+  @CheckForNull
   protected Entry<K, V> standardPollFirstEntry() {
     return Iterators.pollNext(entrySet().iterator());
   }
 
   @Override
+  @CheckForNull
   public Entry<K, V> pollLastEntry() {
     return delegate().pollLastEntry();
   }
@@ -254,6 +279,7 @@ public Entry<K, V> pollLastEntry() {
    * entrySet} of {@code descendingMap}. If you override {@code descendingMap}, you may wish to
    * override {@code pollFirstEntry} to forward to this implementation.
    */
+  @CheckForNull
   protected Entry<K, V> standardPollLastEntry() {
     return Iterators.pollNext(descendingMap().entrySet().iterator());
   }
@@ -287,8 +313,8 @@ NavigableMap<K, V> forward() {
     @Override
     protected Iterator<Entry<K, V>> entryIterator() {
       return new Iterator<Entry<K, V>>() {
-        private Entry<K, V> toRemove = null;
-        private Entry<K, V> nextOrNull = forward().lastEntry();
+        @CheckForNull private Entry<K, V> toRemove = null;
+        @CheckForNull private Entry<K, V> nextOrNull = forward().lastEntry();
 
         @Override
         public boolean hasNext() {
@@ -297,7 +323,7 @@ public boolean hasNext() {
 
         @Override
         public java.util.Map.Entry<K, V> next() {
-          if (!hasNext()) {
+          if (nextOrNull == null) {
             throw new NoSuchElementException();
           }
           try {
@@ -310,7 +336,9 @@ public java.util.Map.Entry<K, V> next() {
 
         @Override
         public void remove() {
-          checkRemove(toRemove != null);
+          if (toRemove == null) {
+            throw new IllegalStateException("no calls to next() since the last call to remove()");
+          }
           forward().remove(toRemove.getKey());
           toRemove = null;
         }
@@ -362,22 +390,27 @@ protected NavigableSet<K> standardDescendingKeySet() {
    * wish to override {@code subMap} to forward to this implementation.
    */
   @Override
-  protected SortedMap<K, V> standardSubMap(K fromKey, K toKey) {
+  protected SortedMap<K, V> standardSubMap(
+      @ParametricNullness K fromKey, @ParametricNullness K toKey) {
     return subMap(fromKey, true, toKey, false);
   }
 
   @Override
-  public NavigableMap<K, V> subMap(K fromKey, boolean fromInclusive, K toKey, boolean toInclusive) {
+  public NavigableMap<K, V> subMap(
+      @ParametricNullness K fromKey,
+      boolean fromInclusive,
+      @ParametricNullness K toKey,
+      boolean toInclusive) {
     return delegate().subMap(fromKey, fromInclusive, toKey, toInclusive);
   }
 
   @Override
-  public NavigableMap<K, V> headMap(K toKey, boolean inclusive) {
+  public NavigableMap<K, V> headMap(@ParametricNullness K toKey, boolean inclusive) {
     return delegate().headMap(toKey, inclusive);
   }
 
   @Override
-  public NavigableMap<K, V> tailMap(K fromKey, boolean inclusive) {
+  public NavigableMap<K, V> tailMap(@ParametricNullness K fromKey, boolean inclusive) {
     return delegate().tailMap(fromKey, inclusive);
   }
 
@@ -386,7 +419,7 @@ public NavigableMap<K, V> tailMap(K fromKey, boolean inclusive) {
    * boolean)}. If you override {@code headMap(K, boolean)}, you may wish to override {@code
    * headMap} to forward to this implementation.
    */
-  protected SortedMap<K, V> standardHeadMap(K toKey) {
+  protected SortedMap<K, V> standardHeadMap(@ParametricNullness K toKey) {
     return headMap(toKey, false);
   }
 
@@ -395,7 +428,7 @@ protected SortedMap<K, V> standardHeadMap(K toKey) {
    * boolean)}. If you override {@code tailMap(K, boolean)}, you may wish to override {@code
    * tailMap} to forward to this implementation.
    */
-  protected SortedMap<K, V> standardTailMap(K fromKey) {
+  protected SortedMap<K, V> standardTailMap(@ParametricNullness K fromKey) {
     return tailMap(fromKey, true);
   }
 }
diff --git a/android/guava/src/com/google/common/collect/ForwardingNavigableSet.java b/android/guava/src/com/google/common/collect/ForwardingNavigableSet.java
index 827698edd545..6822aa87d4fc 100644
--- a/android/guava/src/com/google/common/collect/ForwardingNavigableSet.java
+++ b/android/guava/src/com/google/common/collect/ForwardingNavigableSet.java
@@ -21,6 +21,8 @@
 import java.util.Iterator;
 import java.util.NavigableSet;
 import java.util.SortedSet;
+import javax.annotation.CheckForNull;
+import org.checkerframework.checker.nullness.qual.Nullable;
 
 /**
  * A navigable set which forwards all its method calls to another navigable set. Subclasses should
@@ -49,8 +51,9 @@
  * @since 12.0
  */
 @GwtIncompatible
-public abstract class ForwardingNavigableSet<E> extends ForwardingSortedSet<E>
-    implements NavigableSet<E> {
+@ElementTypesAreNonnullByDefault
+public abstract class ForwardingNavigableSet<E extends @Nullable Object>
+    extends ForwardingSortedSet<E> implements NavigableSet<E> {
 
   /** Constructor for use by subclasses. */
   protected ForwardingNavigableSet() {}
@@ -59,7 +62,8 @@ protected ForwardingNavigableSet() {}
   protected abstract NavigableSet<E> delegate();
 
   @Override
-  public E lower(E e) {
+  @CheckForNull
+  public E lower(@ParametricNullness E e) {
     return delegate().lower(e);
   }
 
@@ -68,12 +72,14 @@ public E lower(E e) {
    * {@link #headSet(Object, boolean)}. If you override {@link #headSet(Object, boolean)}, you may
    * wish to override {@link #lower} to forward to this implementation.
    */
-  protected E standardLower(E e) {
+  @CheckForNull
+  protected E standardLower(@ParametricNullness E e) {
     return Iterators.getNext(headSet(e, false).descendingIterator(), null);
   }
 
   @Override
-  public E floor(E e) {
+  @CheckForNull
+  public E floor(@ParametricNullness E e) {
     return delegate().floor(e);
   }
 
@@ -82,12 +88,14 @@ public E floor(E e) {
    * {@link #headSet(Object, boolean)}. If you override {@link #headSet(Object, boolean)}, you may
    * wish to override {@link #floor} to forward to this implementation.
    */
-  protected E standardFloor(E e) {
+  @CheckForNull
+  protected E standardFloor(@ParametricNullness E e) {
     return Iterators.getNext(headSet(e, true).descendingIterator(), null);
   }
 
   @Override
-  public E ceiling(E e) {
+  @CheckForNull
+  public E ceiling(@ParametricNullness E e) {
     return delegate().ceiling(e);
   }
 
@@ -96,12 +104,14 @@ public E ceiling(E e) {
    * #tailSet(Object, boolean)}. If you override {@link #tailSet(Object, boolean)}, you may wish to
    * override {@link #ceiling} to forward to this implementation.
    */
-  protected E standardCeiling(E e) {
+  @CheckForNull
+  protected E standardCeiling(@ParametricNullness E e) {
     return Iterators.getNext(tailSet(e, true).iterator(), null);
   }
 
   @Override
-  public E higher(E e) {
+  @CheckForNull
+  public E higher(@ParametricNullness E e) {
     return delegate().higher(e);
   }
 
@@ -110,11 +120,13 @@ public E higher(E e) {
    * #tailSet(Object, boolean)}. If you override {@link #tailSet(Object, boolean)}, you may wish to
    * override {@link #higher} to forward to this implementation.
    */
-  protected E standardHigher(E e) {
+  @CheckForNull
+  protected E standardHigher(@ParametricNullness E e) {
     return Iterators.getNext(tailSet(e, false).iterator(), null);
   }
 
   @Override
+  @CheckForNull
   public E pollFirst() {
     return delegate().pollFirst();
   }
@@ -124,11 +136,13 @@ public E pollFirst() {
    * override {@link #iterator} you may wish to override {@link #pollFirst} to forward to this
    * implementation.
    */
+  @CheckForNull
   protected E standardPollFirst() {
     return Iterators.pollNext(iterator());
   }
 
   @Override
+  @CheckForNull
   public E pollLast() {
     return delegate().pollLast();
   }
@@ -138,14 +152,17 @@ public E pollLast() {
    * If you override {@link #descendingIterator} you may wish to override {@link #pollLast} to
    * forward to this implementation.
    */
+  @CheckForNull
   protected E standardPollLast() {
     return Iterators.pollNext(descendingIterator());
   }
 
+  @ParametricNullness
   protected E standardFirst() {
     return iterator().next();
   }
 
+  @ParametricNullness
   protected E standardLast() {
     return descendingIterator().next();
   }
@@ -179,7 +196,10 @@ public Iterator<E> descendingIterator() {
 
   @Override
   public NavigableSet<E> subSet(
-      E fromElement, boolean fromInclusive, E toElement, boolean toInclusive) {
+      @ParametricNullness E fromElement,
+      boolean fromInclusive,
+      @ParametricNullness E toElement,
+      boolean toInclusive) {
     return delegate().subSet(fromElement, fromInclusive, toElement, toInclusive);
   }
 
@@ -190,7 +210,10 @@ public NavigableSet<E> subSet(
    */
   @Beta
   protected NavigableSet<E> standardSubSet(
-      E fromElement, boolean fromInclusive, E toElement, boolean toInclusive) {
+      @ParametricNullness E fromElement,
+      boolean fromInclusive,
+      @ParametricNullness E toElement,
+      boolean toInclusive) {
     return tailSet(fromElement, fromInclusive).headSet(toElement, toInclusive);
   }
 
@@ -201,12 +224,13 @@ protected NavigableSet<E> standardSubSet(
    * implementation.
    */
   @Override
-  protected SortedSet<E> standardSubSet(E fromElement, E toElement) {
+  protected SortedSet<E> standardSubSet(
+      @ParametricNullness E fromElement, @ParametricNullness E toElement) {
     return subSet(fromElement, true, toElement, false);
   }
 
   @Override
-  public NavigableSet<E> headSet(E toElement, boolean inclusive) {
+  public NavigableSet<E> headSet(@ParametricNullness E toElement, boolean inclusive) {
     return delegate().headSet(toElement, inclusive);
   }
 
@@ -215,12 +239,12 @@ public NavigableSet<E> headSet(E toElement, boolean inclusive) {
    * boolean)} method. If you override {@link #headSet(Object, boolean)}, you may wish to override
    * {@link #headSet(Object)} to forward to this implementation.
    */
-  protected SortedSet<E> standardHeadSet(E toElement) {
+  protected SortedSet<E> standardHeadSet(@ParametricNullness E toElement) {
     return headSet(toElement, false);
   }
 
   @Override
-  public NavigableSet<E> tailSet(E fromElement, boolean inclusive) {
+  public NavigableSet<E> tailSet(@ParametricNullness E fromElement, boolean inclusive) {
     return delegate().tailSet(fromElement, inclusive);
   }
 
@@ -229,7 +253,7 @@ public NavigableSet<E> tailSet(E fromElement, boolean inclusive) {
    * boolean)} method. If you override {@link #tailSet(Object, boolean)}, you may wish to override
    * {@link #tailSet(Object)} to forward to this implementation.
    */
-  protected SortedSet<E> standardTailSet(E fromElement) {
+  protected SortedSet<E> standardTailSet(@ParametricNullness E fromElement) {
     return tailSet(fromElement, true);
   }
 }
diff --git a/android/guava/src/com/google/common/collect/ForwardingObject.java b/android/guava/src/com/google/common/collect/ForwardingObject.java
index 712b14fa1343..64af9082d224 100644
--- a/android/guava/src/com/google/common/collect/ForwardingObject.java
+++ b/android/guava/src/com/google/common/collect/ForwardingObject.java
@@ -44,6 +44,7 @@
  * @since 2.0
  */
 @GwtCompatible
+@ElementTypesAreNonnullByDefault
 public abstract class ForwardingObject {
 
   /** Constructor for use by subclasses. */
diff --git a/android/guava/src/com/google/common/collect/ForwardingQueue.java b/android/guava/src/com/google/common/collect/ForwardingQueue.java
index f77e5608d3ff..43c2eaafb56d 100644
--- a/android/guava/src/com/google/common/collect/ForwardingQueue.java
+++ b/android/guava/src/com/google/common/collect/ForwardingQueue.java
@@ -20,6 +20,8 @@
 import com.google.errorprone.annotations.CanIgnoreReturnValue;
 import java.util.NoSuchElementException;
 import java.util.Queue;
+import javax.annotation.CheckForNull;
+import org.checkerframework.checker.nullness.qual.Nullable;
 
 /**
  * A queue which forwards all its method calls to another queue. Subclasses should override one or
@@ -44,7 +46,9 @@
  * @since 2.0
  */
 @GwtCompatible
-public abstract class ForwardingQueue<E> extends ForwardingCollection<E> implements Queue<E> {
+@ElementTypesAreNonnullByDefault
+public abstract class ForwardingQueue<E extends @Nullable Object> extends ForwardingCollection<E>
+    implements Queue<E> {
 
   /** Constructor for use by subclasses. */
   protected ForwardingQueue() {}
@@ -54,28 +58,32 @@ protected ForwardingQueue() {}
 
   @CanIgnoreReturnValue // TODO(cpovirk): Consider removing this?
   @Override
-  public boolean offer(E o) {
+  public boolean offer(@ParametricNullness E o) {
     return delegate().offer(o);
   }
 
   @CanIgnoreReturnValue // TODO(cpovirk): Consider removing this?
   @Override
+  @CheckForNull
   public E poll() {
     return delegate().poll();
   }
 
   @CanIgnoreReturnValue
   @Override
+  @ParametricNullness
   public E remove() {
     return delegate().remove();
   }
 
   @Override
+  @CheckForNull
   public E peek() {
     return delegate().peek();
   }
 
   @Override
+  @ParametricNullness
   public E element() {
     return delegate().element();
   }
@@ -86,7 +94,7 @@ public E element() {
    *
    * @since 7.0
    */
-  protected boolean standardOffer(E e) {
+  protected boolean standardOffer(@ParametricNullness E e) {
     try {
       return add(e);
     } catch (IllegalStateException caught) {
@@ -100,6 +108,7 @@ protected boolean standardOffer(E e) {
    *
    * @since 7.0
    */
+  @CheckForNull
   protected E standardPeek() {
     try {
       return element();
@@ -114,6 +123,7 @@ protected E standardPeek() {
    *
    * @since 7.0
    */
+  @CheckForNull
   protected E standardPoll() {
     try {
       return remove();
diff --git a/android/guava/src/com/google/common/collect/ForwardingSet.java b/android/guava/src/com/google/common/collect/ForwardingSet.java
index 73b1413a3c5d..bc27272b0267 100644
--- a/android/guava/src/com/google/common/collect/ForwardingSet.java
+++ b/android/guava/src/com/google/common/collect/ForwardingSet.java
@@ -21,7 +21,8 @@
 import com.google.common.annotations.GwtCompatible;
 import java.util.Collection;
 import java.util.Set;
-import org.checkerframework.checker.nullness.compatqual.NullableDecl;
+import javax.annotation.CheckForNull;
+import org.checkerframework.checker.nullness.qual.Nullable;
 
 /**
  * A set which forwards all its method calls to another set. Subclasses should override one or more
@@ -46,7 +47,9 @@
  * @since 2.0
  */
 @GwtCompatible
-public abstract class ForwardingSet<E> extends ForwardingCollection<E> implements Set<E> {
+@ElementTypesAreNonnullByDefault
+public abstract class ForwardingSet<E extends @Nullable Object> extends ForwardingCollection<E>
+    implements Set<E> {
   // TODO(lowasser): identify places where thread safety is actually lost
 
   /** Constructor for use by subclasses. */
@@ -56,7 +59,7 @@ protected ForwardingSet() {}
   protected abstract Set<E> delegate();
 
   @Override
-  public boolean equals(@NullableDecl Object object) {
+  public boolean equals(@CheckForNull Object object) {
     return object == this || delegate().equals(object);
   }
 
@@ -84,7 +87,7 @@ protected boolean standardRemoveAll(Collection<?> collection) {
    *
    * @since 7.0
    */
-  protected boolean standardEquals(@NullableDecl Object object) {
+  protected boolean standardEquals(@CheckForNull Object object) {
     return Sets.equalsImpl(this, object);
   }
 
diff --git a/android/guava/src/com/google/common/collect/ForwardingSetMultimap.java b/android/guava/src/com/google/common/collect/ForwardingSetMultimap.java
index 61a0de2bd19b..5077c6803cf9 100644
--- a/android/guava/src/com/google/common/collect/ForwardingSetMultimap.java
+++ b/android/guava/src/com/google/common/collect/ForwardingSetMultimap.java
@@ -20,7 +20,8 @@
 import com.google.errorprone.annotations.CanIgnoreReturnValue;
 import java.util.Map.Entry;
 import java.util.Set;
-import org.checkerframework.checker.nullness.compatqual.NullableDecl;
+import javax.annotation.CheckForNull;
+import org.checkerframework.checker.nullness.qual.Nullable;
 
 /**
  * A set multimap which forwards all its method calls to another set multimap. Subclasses should
@@ -35,8 +36,9 @@
  * @since 3.0
  */
 @GwtCompatible
-public abstract class ForwardingSetMultimap<K, V> extends ForwardingMultimap<K, V>
-    implements SetMultimap<K, V> {
+@ElementTypesAreNonnullByDefault
+public abstract class ForwardingSetMultimap<K extends @Nullable Object, V extends @Nullable Object>
+    extends ForwardingMultimap<K, V> implements SetMultimap<K, V> {
 
   @Override
   protected abstract SetMultimap<K, V> delegate();
@@ -47,19 +49,19 @@ public Set<Entry<K, V>> entries() {
   }
 
   @Override
-  public Set<V> get(@NullableDecl K key) {
+  public Set<V> get(@ParametricNullness K key) {
     return delegate().get(key);
   }
 
   @CanIgnoreReturnValue
   @Override
-  public Set<V> removeAll(@NullableDecl Object key) {
+  public Set<V> removeAll(@CheckForNull Object key) {
     return delegate().removeAll(key);
   }
 
   @CanIgnoreReturnValue
   @Override
-  public Set<V> replaceValues(K key, Iterable<? extends V> values) {
+  public Set<V> replaceValues(@ParametricNullness K key, Iterable<? extends V> values) {
     return delegate().replaceValues(key, values);
   }
 }
diff --git a/android/guava/src/com/google/common/collect/ForwardingSortedMap.java b/android/guava/src/com/google/common/collect/ForwardingSortedMap.java
index 4866fb9850b6..e0882abc7aa9 100644
--- a/android/guava/src/com/google/common/collect/ForwardingSortedMap.java
+++ b/android/guava/src/com/google/common/collect/ForwardingSortedMap.java
@@ -23,7 +23,8 @@
 import java.util.Comparator;
 import java.util.NoSuchElementException;
 import java.util.SortedMap;
-import org.checkerframework.checker.nullness.compatqual.NullableDecl;
+import javax.annotation.CheckForNull;
+import org.checkerframework.checker.nullness.qual.Nullable;
 
 /**
  * A sorted map which forwards all its method calls to another sorted map. Subclasses should
@@ -51,8 +52,9 @@
  * @since 2.0
  */
 @GwtCompatible
-public abstract class ForwardingSortedMap<K, V> extends ForwardingMap<K, V>
-    implements SortedMap<K, V> {
+@ElementTypesAreNonnullByDefault
+public abstract class ForwardingSortedMap<K extends @Nullable Object, V extends @Nullable Object>
+    extends ForwardingMap<K, V> implements SortedMap<K, V> {
   // TODO(lowasser): identify places where thread safety is actually lost
 
   /** Constructor for use by subclasses. */
@@ -62,32 +64,35 @@ protected ForwardingSortedMap() {}
   protected abstract SortedMap<K, V> delegate();
 
   @Override
+  @CheckForNull
   public Comparator<? super K> comparator() {
     return delegate().comparator();
   }
 
   @Override
+  @ParametricNullness
   public K firstKey() {
     return delegate().firstKey();
   }
 
   @Override
-  public SortedMap<K, V> headMap(K toKey) {
+  public SortedMap<K, V> headMap(@ParametricNullness K toKey) {
     return delegate().headMap(toKey);
   }
 
   @Override
+  @ParametricNullness
   public K lastKey() {
     return delegate().lastKey();
   }
 
   @Override
-  public SortedMap<K, V> subMap(K fromKey, K toKey) {
+  public SortedMap<K, V> subMap(@ParametricNullness K fromKey, @ParametricNullness K toKey) {
     return delegate().subMap(fromKey, toKey);
   }
 
   @Override
-  public SortedMap<K, V> tailMap(K fromKey) {
+  public SortedMap<K, V> tailMap(@ParametricNullness K fromKey) {
     return delegate().tailMap(fromKey);
   }
 
@@ -106,14 +111,14 @@ public StandardKeySet() {
     }
   }
 
-  // unsafe, but worst case is a CCE is thrown, which callers will be expecting
-  @SuppressWarnings("unchecked")
-  private int unsafeCompare(Object k1, Object k2) {
-    Comparator<? super K> comparator = comparator();
+  // unsafe, but worst case is a CCE or NPE is thrown, which callers will be expecting
+  @SuppressWarnings({"unchecked", "nullness"})
+  static int unsafeCompare(
+      @CheckForNull Comparator<?> comparator, @CheckForNull Object o1, @CheckForNull Object o2) {
     if (comparator == null) {
-      return ((Comparable<Object>) k1).compareTo(k2);
+      return ((Comparable<@Nullable Object>) o1).compareTo(o2);
     } else {
-      return ((Comparator<Object>) comparator).compare(k1, k2);
+      return ((Comparator<@Nullable Object>) comparator).compare(o1, o2);
     }
   }
 
@@ -126,13 +131,13 @@ private int unsafeCompare(Object k1, Object k2) {
    */
   @Override
   @Beta
-  protected boolean standardContainsKey(@NullableDecl Object key) {
+  protected boolean standardContainsKey(@CheckForNull Object key) {
     try {
-      // any CCE will be caught
-      @SuppressWarnings("unchecked")
-      SortedMap<Object, V> self = (SortedMap<Object, V>) this;
+      // any CCE or NPE will be caught
+      @SuppressWarnings({"unchecked", "nullness"})
+      SortedMap<@Nullable Object, V> self = (SortedMap<@Nullable Object, V>) this;
       Object ceilingKey = self.tailMap(key).firstKey();
-      return unsafeCompare(ceilingKey, key) == 0;
+      return unsafeCompare(comparator(), ceilingKey, key) == 0;
     } catch (ClassCastException | NoSuchElementException | NullPointerException e) {
       return false;
     }
@@ -147,7 +152,7 @@ protected boolean standardContainsKey(@NullableDecl Object key) {
    */
   @Beta
   protected SortedMap<K, V> standardSubMap(K fromKey, K toKey) {
-    checkArgument(unsafeCompare(fromKey, toKey) <= 0, "fromKey must be <= toKey");
+    checkArgument(unsafeCompare(comparator(), fromKey, toKey) <= 0, "fromKey must be <= toKey");
     return tailMap(fromKey).headMap(toKey);
   }
 }
diff --git a/android/guava/src/com/google/common/collect/ForwardingSortedMultiset.java b/android/guava/src/com/google/common/collect/ForwardingSortedMultiset.java
index 1d34fb3d559f..4626d3193a58 100644
--- a/android/guava/src/com/google/common/collect/ForwardingSortedMultiset.java
+++ b/android/guava/src/com/google/common/collect/ForwardingSortedMultiset.java
@@ -19,6 +19,8 @@
 import java.util.Comparator;
 import java.util.Iterator;
 import java.util.NavigableSet;
+import javax.annotation.CheckForNull;
+import org.checkerframework.checker.nullness.qual.Nullable;
 
 /**
  * A sorted multiset which forwards all its method calls to another sorted multiset. Subclasses
@@ -44,8 +46,9 @@
  */
 @Beta
 @GwtCompatible(emulated = true)
-public abstract class ForwardingSortedMultiset<E> extends ForwardingMultiset<E>
-    implements SortedMultiset<E> {
+@ElementTypesAreNonnullByDefault
+public abstract class ForwardingSortedMultiset<E extends @Nullable Object>
+    extends ForwardingMultiset<E> implements SortedMultiset<E> {
   /** Constructor for use by subclasses. */
   protected ForwardingSortedMultiset() {}
 
@@ -110,6 +113,7 @@ SortedMultiset<E> forwardMultiset() {
   }
 
   @Override
+  @CheckForNull
   public Entry<E> firstEntry() {
     return delegate().firstEntry();
   }
@@ -120,6 +124,7 @@ public Entry<E> firstEntry() {
    * <p>If you override {@link #entrySet()}, you may wish to override {@link #firstEntry()} to
    * forward to this implementation.
    */
+  @CheckForNull
   protected Entry<E> standardFirstEntry() {
     Iterator<Entry<E>> entryIterator = entrySet().iterator();
     if (!entryIterator.hasNext()) {
@@ -130,6 +135,7 @@ protected Entry<E> standardFirstEntry() {
   }
 
   @Override
+  @CheckForNull
   public Entry<E> lastEntry() {
     return delegate().lastEntry();
   }
@@ -141,6 +147,7 @@ public Entry<E> lastEntry() {
    * <p>If you override {@link #descendingMultiset} or {@link #entrySet()}, you may wish to override
    * {@link #firstEntry()} to forward to this implementation.
    */
+  @CheckForNull
   protected Entry<E> standardLastEntry() {
     Iterator<Entry<E>> entryIterator = descendingMultiset().entrySet().iterator();
     if (!entryIterator.hasNext()) {
@@ -151,6 +158,7 @@ protected Entry<E> standardLastEntry() {
   }
 
   @Override
+  @CheckForNull
   public Entry<E> pollFirstEntry() {
     return delegate().pollFirstEntry();
   }
@@ -161,6 +169,7 @@ public Entry<E> pollFirstEntry() {
    * <p>If you override {@link #entrySet()}, you may wish to override {@link #pollFirstEntry()} to
    * forward to this implementation.
    */
+  @CheckForNull
   protected Entry<E> standardPollFirstEntry() {
     Iterator<Entry<E>> entryIterator = entrySet().iterator();
     if (!entryIterator.hasNext()) {
@@ -173,6 +182,7 @@ protected Entry<E> standardPollFirstEntry() {
   }
 
   @Override
+  @CheckForNull
   public Entry<E> pollLastEntry() {
     return delegate().pollLastEntry();
   }
@@ -184,6 +194,7 @@ public Entry<E> pollLastEntry() {
    * <p>If you override {@link #descendingMultiset()} or {@link #entrySet()}, you may wish to
    * override {@link #pollLastEntry()} to forward to this implementation.
    */
+  @CheckForNull
   protected Entry<E> standardPollLastEntry() {
     Iterator<Entry<E>> entryIterator = descendingMultiset().entrySet().iterator();
     if (!entryIterator.hasNext()) {
@@ -196,13 +207,16 @@ protected Entry<E> standardPollLastEntry() {
   }
 
   @Override
-  public SortedMultiset<E> headMultiset(E upperBound, BoundType boundType) {
+  public SortedMultiset<E> headMultiset(@ParametricNullness E upperBound, BoundType boundType) {
     return delegate().headMultiset(upperBound, boundType);
   }
 
   @Override
   public SortedMultiset<E> subMultiset(
-      E lowerBound, BoundType lowerBoundType, E upperBound, BoundType upperBoundType) {
+      @ParametricNullness E lowerBound,
+      BoundType lowerBoundType,
+      @ParametricNullness E upperBound,
+      BoundType upperBoundType) {
     return delegate().subMultiset(lowerBound, lowerBoundType, upperBound, upperBoundType);
   }
 
@@ -215,12 +229,15 @@ public SortedMultiset<E> subMultiset(
    * #subMultiset(Object, BoundType, Object, BoundType)} to forward to this implementation.
    */
   protected SortedMultiset<E> standardSubMultiset(
-      E lowerBound, BoundType lowerBoundType, E upperBound, BoundType upperBoundType) {
+      @ParametricNullness E lowerBound,
+      BoundType lowerBoundType,
+      @ParametricNullness E upperBound,
+      BoundType upperBoundType) {
     return tailMultiset(lowerBound, lowerBoundType).headMultiset(upperBound, upperBoundType);
   }
 
   @Override
-  public SortedMultiset<E> tailMultiset(E lowerBound, BoundType boundType) {
+  public SortedMultiset<E> tailMultiset(@ParametricNullness E lowerBound, BoundType boundType) {
     return delegate().tailMultiset(lowerBound, boundType);
   }
 }
diff --git a/android/guava/src/com/google/common/collect/ForwardingSortedSet.java b/android/guava/src/com/google/common/collect/ForwardingSortedSet.java
index 9879944838e8..32625afd161f 100644
--- a/android/guava/src/com/google/common/collect/ForwardingSortedSet.java
+++ b/android/guava/src/com/google/common/collect/ForwardingSortedSet.java
@@ -16,13 +16,16 @@
 
 package com.google.common.collect;
 
+import static com.google.common.collect.ForwardingSortedMap.unsafeCompare;
+
 import com.google.common.annotations.Beta;
 import com.google.common.annotations.GwtCompatible;
 import java.util.Comparator;
 import java.util.Iterator;
 import java.util.NoSuchElementException;
 import java.util.SortedSet;
-import org.checkerframework.checker.nullness.compatqual.NullableDecl;
+import javax.annotation.CheckForNull;
+import org.checkerframework.checker.nullness.qual.Nullable;
 
 /**
  * A sorted set which forwards all its method calls to another sorted set. Subclasses should
@@ -52,7 +55,9 @@
  * @since 2.0
  */
 @GwtCompatible
-public abstract class ForwardingSortedSet<E> extends ForwardingSet<E> implements SortedSet<E> {
+@ElementTypesAreNonnullByDefault
+public abstract class ForwardingSortedSet<E extends @Nullable Object> extends ForwardingSet<E>
+    implements SortedSet<E> {
 
   /** Constructor for use by subclasses. */
   protected ForwardingSortedSet() {}
@@ -61,44 +66,38 @@ protected ForwardingSortedSet() {}
   protected abstract SortedSet<E> delegate();
 
   @Override
+  @CheckForNull
   public Comparator<? super E> comparator() {
     return delegate().comparator();
   }
 
   @Override
+  @ParametricNullness
   public E first() {
     return delegate().first();
   }
 
   @Override
-  public SortedSet<E> headSet(E toElement) {
+  public SortedSet<E> headSet(@ParametricNullness E toElement) {
     return delegate().headSet(toElement);
   }
 
   @Override
+  @ParametricNullness
   public E last() {
     return delegate().last();
   }
 
   @Override
-  public SortedSet<E> subSet(E fromElement, E toElement) {
+  public SortedSet<E> subSet(@ParametricNullness E fromElement, @ParametricNullness E toElement) {
     return delegate().subSet(fromElement, toElement);
   }
 
   @Override
-  public SortedSet<E> tailSet(E fromElement) {
+  public SortedSet<E> tailSet(@ParametricNullness E fromElement) {
     return delegate().tailSet(fromElement);
   }
 
-  // unsafe, but worst case is a CCE is thrown, which callers will be expecting
-  @SuppressWarnings("unchecked")
-  private int unsafeCompare(@NullableDecl Object o1, @NullableDecl Object o2) {
-    Comparator<? super E> comparator = comparator();
-    return (comparator == null)
-        ? ((Comparable<Object>) o1).compareTo(o2)
-        : ((Comparator<Object>) comparator).compare(o1, o2);
-  }
-
   /**
    * A sensible definition of {@link #contains} in terms of the {@code first()} method of {@link
    * #tailSet}. If you override {@link #tailSet}, you may wish to override {@link #contains} to
@@ -108,13 +107,13 @@ private int unsafeCompare(@NullableDecl Object o1, @NullableDecl Object o2) {
    */
   @Override
   @Beta
-  protected boolean standardContains(@NullableDecl Object object) {
+  protected boolean standardContains(@CheckForNull Object object) {
     try {
-      // any ClassCastExceptions are caught
-      @SuppressWarnings("unchecked")
-      SortedSet<Object> self = (SortedSet<Object>) this;
+      // any ClassCastExceptions and NullPointerExceptions are caught
+      @SuppressWarnings({"unchecked", "nullness"})
+      SortedSet<@Nullable Object> self = (SortedSet<@Nullable Object>) this;
       Object ceiling = self.tailSet(object).first();
-      return unsafeCompare(ceiling, object) == 0;
+      return unsafeCompare(comparator(), ceiling, object) == 0;
     } catch (ClassCastException | NoSuchElementException | NullPointerException e) {
       return false;
     }
@@ -129,15 +128,15 @@ protected boolean standardContains(@NullableDecl Object object) {
    */
   @Override
   @Beta
-  protected boolean standardRemove(@NullableDecl Object object) {
+  protected boolean standardRemove(@CheckForNull Object object) {
     try {
-      // any ClassCastExceptions are caught
-      @SuppressWarnings("unchecked")
-      SortedSet<Object> self = (SortedSet<Object>) this;
-      Iterator<Object> iterator = self.tailSet(object).iterator();
+      // any ClassCastExceptions and NullPointerExceptions are caught
+      @SuppressWarnings({"unchecked", "nullness"})
+      SortedSet<@Nullable Object> self = (SortedSet<@Nullable Object>) this;
+      Iterator<?> iterator = self.tailSet(object).iterator();
       if (iterator.hasNext()) {
         Object ceiling = iterator.next();
-        if (unsafeCompare(ceiling, object) == 0) {
+        if (unsafeCompare(comparator(), ceiling, object) == 0) {
           iterator.remove();
           return true;
         }
@@ -156,7 +155,8 @@ protected boolean standardRemove(@NullableDecl Object object) {
    * @since 7.0
    */
   @Beta
-  protected SortedSet<E> standardSubSet(E fromElement, E toElement) {
+  protected SortedSet<E> standardSubSet(
+      @ParametricNullness E fromElement, @ParametricNullness E toElement) {
     return tailSet(fromElement).headSet(toElement);
   }
 }
diff --git a/android/guava/src/com/google/common/collect/ForwardingSortedSetMultimap.java b/android/guava/src/com/google/common/collect/ForwardingSortedSetMultimap.java
index 78319a7732db..b91a68b3445a 100644
--- a/android/guava/src/com/google/common/collect/ForwardingSortedSetMultimap.java
+++ b/android/guava/src/com/google/common/collect/ForwardingSortedSetMultimap.java
@@ -19,7 +19,8 @@
 import com.google.common.annotations.GwtCompatible;
 import java.util.Comparator;
 import java.util.SortedSet;
-import org.checkerframework.checker.nullness.compatqual.NullableDecl;
+import javax.annotation.CheckForNull;
+import org.checkerframework.checker.nullness.qual.Nullable;
 
 /**
  * A sorted set multimap which forwards all its method calls to another sorted set multimap.
@@ -34,8 +35,10 @@
  * @since 3.0
  */
 @GwtCompatible
-public abstract class ForwardingSortedSetMultimap<K, V> extends ForwardingSetMultimap<K, V>
-    implements SortedSetMultimap<K, V> {
+@ElementTypesAreNonnullByDefault
+public abstract class ForwardingSortedSetMultimap<
+        K extends @Nullable Object, V extends @Nullable Object>
+    extends ForwardingSetMultimap<K, V> implements SortedSetMultimap<K, V> {
 
   /** Constructor for use by subclasses. */
   protected ForwardingSortedSetMultimap() {}
@@ -44,21 +47,22 @@ protected ForwardingSortedSetMultimap() {}
   protected abstract SortedSetMultimap<K, V> delegate();
 
   @Override
-  public SortedSet<V> get(@NullableDecl K key) {
+  public SortedSet<V> get(@ParametricNullness K key) {
     return delegate().get(key);
   }
 
   @Override
-  public SortedSet<V> removeAll(@NullableDecl Object key) {
+  public SortedSet<V> removeAll(@CheckForNull Object key) {
     return delegate().removeAll(key);
   }
 
   @Override
-  public SortedSet<V> replaceValues(K key, Iterable<? extends V> values) {
+  public SortedSet<V> replaceValues(@ParametricNullness K key, Iterable<? extends V> values) {
     return delegate().replaceValues(key, values);
   }
 
   @Override
+  @CheckForNull
   public Comparator<? super V> valueComparator() {
     return delegate().valueComparator();
   }
diff --git a/android/guava/src/com/google/common/collect/ForwardingTable.java b/android/guava/src/com/google/common/collect/ForwardingTable.java
index 71a54cfbcfea..4fcb858b725f 100644
--- a/android/guava/src/com/google/common/collect/ForwardingTable.java
+++ b/android/guava/src/com/google/common/collect/ForwardingTable.java
@@ -21,6 +21,8 @@
 import java.util.Collection;
 import java.util.Map;
 import java.util.Set;
+import javax.annotation.CheckForNull;
+import org.checkerframework.checker.nullness.qual.Nullable;
 
 /**
  * A table which forwards all its method calls to another table. Subclasses should override one or
@@ -31,7 +33,10 @@
  * @since 7.0
  */
 @GwtCompatible
-public abstract class ForwardingTable<R, C, V> extends ForwardingObject implements Table<R, C, V> {
+@ElementTypesAreNonnullByDefault
+public abstract class ForwardingTable<
+        R extends @Nullable Object, C extends @Nullable Object, V extends @Nullable Object>
+    extends ForwardingObject implements Table<R, C, V> {
   /** Constructor for use by subclasses. */
   protected ForwardingTable() {}
 
@@ -49,7 +54,7 @@ public void clear() {
   }
 
   @Override
-  public Map<R, V> column(C columnKey) {
+  public Map<R, V> column(@ParametricNullness C columnKey) {
     return delegate().column(columnKey);
   }
 
@@ -64,27 +69,28 @@ public Map<C, Map<R, V>> columnMap() {
   }
 
   @Override
-  public boolean contains(Object rowKey, Object columnKey) {
+  public boolean contains(@CheckForNull Object rowKey, @CheckForNull Object columnKey) {
     return delegate().contains(rowKey, columnKey);
   }
 
   @Override
-  public boolean containsColumn(Object columnKey) {
+  public boolean containsColumn(@CheckForNull Object columnKey) {
     return delegate().containsColumn(columnKey);
   }
 
   @Override
-  public boolean containsRow(Object rowKey) {
+  public boolean containsRow(@CheckForNull Object rowKey) {
     return delegate().containsRow(rowKey);
   }
 
   @Override
-  public boolean containsValue(Object value) {
+  public boolean containsValue(@CheckForNull Object value) {
     return delegate().containsValue(value);
   }
 
   @Override
-  public V get(Object rowKey, Object columnKey) {
+  @CheckForNull
+  public V get(@CheckForNull Object rowKey, @CheckForNull Object columnKey) {
     return delegate().get(rowKey, columnKey);
   }
 
@@ -95,7 +101,9 @@ public boolean isEmpty() {
 
   @CanIgnoreReturnValue
   @Override
-  public V put(R rowKey, C columnKey, V value) {
+  @CheckForNull
+  public V put(
+      @ParametricNullness R rowKey, @ParametricNullness C columnKey, @ParametricNullness V value) {
     return delegate().put(rowKey, columnKey, value);
   }
 
@@ -106,12 +114,13 @@ public void putAll(Table<? extends R, ? extends C, ? extends V> table) {
 
   @CanIgnoreReturnValue
   @Override
-  public V remove(Object rowKey, Object columnKey) {
+  @CheckForNull
+  public V remove(@CheckForNull Object rowKey, @CheckForNull Object columnKey) {
     return delegate().remove(rowKey, columnKey);
   }
 
   @Override
-  public Map<C, V> row(R rowKey) {
+  public Map<C, V> row(@ParametricNullness R rowKey) {
     return delegate().row(rowKey);
   }
 
@@ -136,7 +145,7 @@ public Collection<V> values() {
   }
 
   @Override
-  public boolean equals(Object obj) {
+  public boolean equals(@CheckForNull Object obj) {
     return (obj == this) || delegate().equals(obj);
   }
 
diff --git a/android/guava/src/com/google/common/collect/GeneralRange.java b/android/guava/src/com/google/common/collect/GeneralRange.java
index 69561872bde8..3d7256ff811f 100644
--- a/android/guava/src/com/google/common/collect/GeneralRange.java
+++ b/android/guava/src/com/google/common/collect/GeneralRange.java
@@ -18,12 +18,14 @@
 import static com.google.common.base.Preconditions.checkNotNull;
 import static com.google.common.collect.BoundType.CLOSED;
 import static com.google.common.collect.BoundType.OPEN;
+import static com.google.common.collect.NullnessCasts.uncheckedCastNullableTToT;
 
 import com.google.common.annotations.GwtCompatible;
 import com.google.common.base.Objects;
 import java.io.Serializable;
 import java.util.Comparator;
-import org.checkerframework.checker.nullness.compatqual.NullableDecl;
+import javax.annotation.CheckForNull;
+import org.checkerframework.checker.nullness.qual.Nullable;
 
 /**
  * A generalized interval on any ordering, for internal use. Supports {@code null}. Unlike {@link
@@ -35,15 +37,16 @@
  * @author Louis Wasserman
  */
 @GwtCompatible(serializable = true)
-final class GeneralRange<T> implements Serializable {
+@ElementTypesAreNonnullByDefault
+final class GeneralRange<T extends @Nullable Object> implements Serializable {
   /** Converts a Range to a GeneralRange. */
   static <T extends Comparable> GeneralRange<T> from(Range<T> range) {
-    @NullableDecl T lowerEndpoint = range.hasLowerBound() ? range.lowerEndpoint() : null;
+    T lowerEndpoint = range.hasLowerBound() ? range.lowerEndpoint() : null;
     BoundType lowerBoundType = range.hasLowerBound() ? range.lowerBoundType() : OPEN;
 
-    @NullableDecl T upperEndpoint = range.hasUpperBound() ? range.upperEndpoint() : null;
+    T upperEndpoint = range.hasUpperBound() ? range.upperEndpoint() : null;
     BoundType upperBoundType = range.hasUpperBound() ? range.upperBoundType() : OPEN;
-    return new GeneralRange<T>(
+    return new GeneralRange<>(
         Ordering.natural(),
         range.hasLowerBound(),
         lowerEndpoint,
@@ -54,56 +57,56 @@ static <T extends Comparable> GeneralRange<T> from(Range<T> range) {
   }
 
   /** Returns the whole range relative to the specified comparator. */
-  static <T> GeneralRange<T> all(Comparator<? super T> comparator) {
-    return new GeneralRange<T>(comparator, false, null, OPEN, false, null, OPEN);
+  static <T extends @Nullable Object> GeneralRange<T> all(Comparator<? super T> comparator) {
+    return new GeneralRange<>(comparator, false, null, OPEN, false, null, OPEN);
   }
 
   /**
    * Returns everything above the endpoint relative to the specified comparator, with the specified
    * endpoint behavior.
    */
-  static <T> GeneralRange<T> downTo(
-      Comparator<? super T> comparator, @NullableDecl T endpoint, BoundType boundType) {
-    return new GeneralRange<T>(comparator, true, endpoint, boundType, false, null, OPEN);
+  static <T extends @Nullable Object> GeneralRange<T> downTo(
+      Comparator<? super T> comparator, @ParametricNullness T endpoint, BoundType boundType) {
+    return new GeneralRange<>(comparator, true, endpoint, boundType, false, null, OPEN);
   }
 
   /**
    * Returns everything below the endpoint relative to the specified comparator, with the specified
    * endpoint behavior.
    */
-  static <T> GeneralRange<T> upTo(
-      Comparator<? super T> comparator, @NullableDecl T endpoint, BoundType boundType) {
-    return new GeneralRange<T>(comparator, false, null, OPEN, true, endpoint, boundType);
+  static <T extends @Nullable Object> GeneralRange<T> upTo(
+      Comparator<? super T> comparator, @ParametricNullness T endpoint, BoundType boundType) {
+    return new GeneralRange<>(comparator, false, null, OPEN, true, endpoint, boundType);
   }
 
   /**
    * Returns everything between the endpoints relative to the specified comparator, with the
    * specified endpoint behavior.
    */
-  static <T> GeneralRange<T> range(
+  static <T extends @Nullable Object> GeneralRange<T> range(
       Comparator<? super T> comparator,
-      @NullableDecl T lower,
+      @ParametricNullness T lower,
       BoundType lowerType,
-      @NullableDecl T upper,
+      @ParametricNullness T upper,
       BoundType upperType) {
-    return new GeneralRange<T>(comparator, true, lower, lowerType, true, upper, upperType);
+    return new GeneralRange<>(comparator, true, lower, lowerType, true, upper, upperType);
   }
 
   private final Comparator<? super T> comparator;
   private final boolean hasLowerBound;
-  @NullableDecl private final T lowerEndpoint;
+  @CheckForNull private final T lowerEndpoint;
   private final BoundType lowerBoundType;
   private final boolean hasUpperBound;
-  @NullableDecl private final T upperEndpoint;
+  @CheckForNull private final T upperEndpoint;
   private final BoundType upperBoundType;
 
   private GeneralRange(
       Comparator<? super T> comparator,
       boolean hasLowerBound,
-      @NullableDecl T lowerEndpoint,
+      @CheckForNull T lowerEndpoint,
       BoundType lowerBoundType,
       boolean hasUpperBound,
-      @NullableDecl T upperEndpoint,
+      @CheckForNull T upperEndpoint,
       BoundType upperBoundType) {
     this.comparator = checkNotNull(comparator);
     this.hasLowerBound = hasLowerBound;
@@ -113,19 +116,29 @@ private GeneralRange(
     this.upperEndpoint = upperEndpoint;
     this.upperBoundType = checkNotNull(upperBoundType);
 
+    // Trigger any exception that the comparator would throw for the endpoints.
+    /*
+     * uncheckedCastNullableTToT is safe as long as the callers are careful to pass a "real" T
+     * whenever they pass `true` for the matching `has*Bound` parameter.
+     */
     if (hasLowerBound) {
-      comparator.compare(lowerEndpoint, lowerEndpoint);
+      comparator.compare(
+          uncheckedCastNullableTToT(lowerEndpoint), uncheckedCastNullableTToT(lowerEndpoint));
     }
     if (hasUpperBound) {
-      comparator.compare(upperEndpoint, upperEndpoint);
+      comparator.compare(
+          uncheckedCastNullableTToT(upperEndpoint), uncheckedCastNullableTToT(upperEndpoint));
     }
+
     if (hasLowerBound && hasUpperBound) {
-      int cmp = comparator.compare(lowerEndpoint, upperEndpoint);
+      int cmp =
+          comparator.compare(
+              uncheckedCastNullableTToT(lowerEndpoint), uncheckedCastNullableTToT(upperEndpoint));
       // be consistent with Range
       checkArgument(
           cmp <= 0, "lowerEndpoint (%s) > upperEndpoint (%s)", lowerEndpoint, upperEndpoint);
       if (cmp == 0) {
-        checkArgument(lowerBoundType != OPEN | upperBoundType != OPEN);
+        checkArgument(lowerBoundType != OPEN || upperBoundType != OPEN);
       }
     }
   }
@@ -143,41 +156,45 @@ boolean hasUpperBound() {
   }
 
   boolean isEmpty() {
-    return (hasUpperBound() && tooLow(getUpperEndpoint()))
-        || (hasLowerBound() && tooHigh(getLowerEndpoint()));
+    // The casts are safe because of the has*Bound() checks.
+    return (hasUpperBound() && tooLow(uncheckedCastNullableTToT(getUpperEndpoint())))
+        || (hasLowerBound() && tooHigh(uncheckedCastNullableTToT(getLowerEndpoint())));
   }
 
-  boolean tooLow(@NullableDecl T t) {
+  boolean tooLow(@ParametricNullness T t) {
     if (!hasLowerBound()) {
       return false;
     }
-    T lbound = getLowerEndpoint();
+    // The cast is safe because of the hasLowerBound() check.
+    T lbound = uncheckedCastNullableTToT(getLowerEndpoint());
     int cmp = comparator.compare(t, lbound);
     return cmp < 0 | (cmp == 0 & getLowerBoundType() == OPEN);
   }
 
-  boolean tooHigh(@NullableDecl T t) {
+  boolean tooHigh(@ParametricNullness T t) {
     if (!hasUpperBound()) {
       return false;
     }
-    T ubound = getUpperEndpoint();
+    // The cast is safe because of the hasUpperBound() check.
+    T ubound = uncheckedCastNullableTToT(getUpperEndpoint());
     int cmp = comparator.compare(t, ubound);
     return cmp > 0 | (cmp == 0 & getUpperBoundType() == OPEN);
   }
 
-  boolean contains(@NullableDecl T t) {
+  boolean contains(@ParametricNullness T t) {
     return !tooLow(t) && !tooHigh(t);
   }
 
   /**
    * Returns the intersection of the two ranges, or an empty range if their intersection is empty.
    */
+  @SuppressWarnings("nullness") // TODO(cpovirk): Add casts as needed. Will be noisy and annoying...
   GeneralRange<T> intersect(GeneralRange<T> other) {
     checkNotNull(other);
     checkArgument(comparator.equals(other.comparator));
 
     boolean hasLowBound = this.hasLowerBound;
-    @NullableDecl T lowEnd = getLowerEndpoint();
+    T lowEnd = getLowerEndpoint();
     BoundType lowType = getLowerBoundType();
     if (!hasLowerBound()) {
       hasLowBound = other.hasLowerBound;
@@ -192,7 +209,7 @@ GeneralRange<T> intersect(GeneralRange<T> other) {
     }
 
     boolean hasUpBound = this.hasUpperBound;
-    @NullableDecl T upEnd = getUpperEndpoint();
+    T upEnd = getUpperEndpoint();
     BoundType upType = getUpperBoundType();
     if (!hasUpperBound()) {
       hasUpBound = other.hasUpperBound;
@@ -216,11 +233,11 @@ GeneralRange<T> intersect(GeneralRange<T> other) {
       }
     }
 
-    return new GeneralRange<T>(comparator, hasLowBound, lowEnd, lowType, hasUpBound, upEnd, upType);
+    return new GeneralRange<>(comparator, hasLowBound, lowEnd, lowType, hasUpBound, upEnd, upType);
   }
 
   @Override
-  public boolean equals(@NullableDecl Object obj) {
+  public boolean equals(@CheckForNull Object obj) {
     if (obj instanceof GeneralRange) {
       GeneralRange<?> r = (GeneralRange<?>) obj;
       return comparator.equals(r.comparator)
@@ -244,14 +261,14 @@ public int hashCode() {
         getUpperBoundType());
   }
 
-  @NullableDecl private transient GeneralRange<T> reverse;
+  @CheckForNull private transient GeneralRange<T> reverse;
 
   /** Returns the same range relative to the reversed comparator. */
   GeneralRange<T> reverse() {
     GeneralRange<T> result = reverse;
     if (result == null) {
       result =
-          new GeneralRange<T>(
+          new GeneralRange<>(
               Ordering.from(comparator).reverse(),
               hasUpperBound,
               getUpperEndpoint(),
@@ -276,6 +293,7 @@ public String toString() {
         + (upperBoundType == CLOSED ? ']' : ')');
   }
 
+  @CheckForNull
   T getLowerEndpoint() {
     return lowerEndpoint;
   }
@@ -284,6 +302,7 @@ BoundType getLowerBoundType() {
     return lowerBoundType;
   }
 
+  @CheckForNull
   T getUpperEndpoint() {
     return upperEndpoint;
   }
diff --git a/android/guava/src/com/google/common/collect/GwtTransient.java b/android/guava/src/com/google/common/collect/GwtTransient.java
index 9c09c53c946f..ce5ea48848c9 100644
--- a/android/guava/src/com/google/common/collect/GwtTransient.java
+++ b/android/guava/src/com/google/common/collect/GwtTransient.java
@@ -33,4 +33,5 @@
 @GwtCompatible
 @Retention(RUNTIME)
 @Target(FIELD)
+@ElementTypesAreNonnullByDefault
 @interface GwtTransient {}
diff --git a/android/guava/src/com/google/common/collect/HashBasedTable.java b/android/guava/src/com/google/common/collect/HashBasedTable.java
index 07c144f6d28b..21882e62d406 100644
--- a/android/guava/src/com/google/common/collect/HashBasedTable.java
+++ b/android/guava/src/com/google/common/collect/HashBasedTable.java
@@ -20,11 +20,9 @@
 
 import com.google.common.annotations.GwtCompatible;
 import com.google.common.base.Supplier;
-import com.google.errorprone.annotations.CanIgnoreReturnValue;
 import java.io.Serializable;
 import java.util.LinkedHashMap;
 import java.util.Map;
-import org.checkerframework.checker.nullness.compatqual.NullableDecl;
 
 /**
  * Implementation of {@link Table} using linked hash tables. This guarantees predictable iteration
@@ -43,12 +41,13 @@
  * concurrently and one of the threads modifies the table, it must be synchronized externally.
  *
  * <p>See the Guava User Guide article on <a href=
- * "https://github.com/google/guava/wiki/NewCollectionTypesExplained#table"> {@code Table}</a>.
+ * "https://github.com/google/guava/wiki/NewCollectionTypesExplained#table">{@code Table}</a>.
  *
  * @author Jared Levy
  * @since 7.0
  */
 @GwtCompatible(serializable = true)
+@ElementTypesAreNonnullByDefault
 public class HashBasedTable<R, C, V> extends StandardTable<R, C, V> {
   private static class Factory<C, V> implements Supplier<Map<C, V>>, Serializable {
     final int expectedSize;
@@ -103,43 +102,5 @@ public static <R, C, V> HashBasedTable<R, C, V> create(
     super(backingMap, factory);
   }
 
-  // Overriding so NullPointerTester test passes.
-
-  @Override
-  public boolean contains(@NullableDecl Object rowKey, @NullableDecl Object columnKey) {
-    return super.contains(rowKey, columnKey);
-  }
-
-  @Override
-  public boolean containsColumn(@NullableDecl Object columnKey) {
-    return super.containsColumn(columnKey);
-  }
-
-  @Override
-  public boolean containsRow(@NullableDecl Object rowKey) {
-    return super.containsRow(rowKey);
-  }
-
-  @Override
-  public boolean containsValue(@NullableDecl Object value) {
-    return super.containsValue(value);
-  }
-
-  @Override
-  public V get(@NullableDecl Object rowKey, @NullableDecl Object columnKey) {
-    return super.get(rowKey, columnKey);
-  }
-
-  @Override
-  public boolean equals(@NullableDecl Object obj) {
-    return super.equals(obj);
-  }
-
-  @CanIgnoreReturnValue
-  @Override
-  public V remove(@NullableDecl Object rowKey, @NullableDecl Object columnKey) {
-    return super.remove(rowKey, columnKey);
-  }
-
   private static final long serialVersionUID = 0;
 }
diff --git a/android/guava/src/com/google/common/collect/HashBiMap.java b/android/guava/src/com/google/common/collect/HashBiMap.java
index 18951fe08be9..8639cb071057 100644
--- a/android/guava/src/com/google/common/collect/HashBiMap.java
+++ b/android/guava/src/com/google/common/collect/HashBiMap.java
@@ -15,6 +15,8 @@
 package com.google.common.collect;
 
 import static com.google.common.base.Preconditions.checkArgument;
+import static com.google.common.collect.NullnessCasts.uncheckedCastNullableTToT;
+import static com.google.common.collect.NullnessCasts.unsafeNull;
 
 import com.google.common.annotations.GwtCompatible;
 import com.google.common.annotations.GwtIncompatible;
@@ -34,7 +36,8 @@
 import java.util.Map;
 import java.util.NoSuchElementException;
 import java.util.Set;
-import org.checkerframework.checker.nullness.compatqual.NullableDecl;
+import javax.annotation.CheckForNull;
+import org.checkerframework.checker.nullness.qual.Nullable;
 
 /**
  * A {@link BiMap} backed by two hash tables. This implementation allows null keys and values. A
@@ -43,17 +46,19 @@
  * <p>This implementation guarantees insertion-based iteration order of its keys.
  *
  * <p>See the Guava User Guide article on <a href=
- * "https://github.com/google/guava/wiki/NewCollectionTypesExplained#bimap"> {@code BiMap} </a>.
+ * "https://github.com/google/guava/wiki/NewCollectionTypesExplained#bimap">{@code BiMap} </a>.
  *
  * @author Louis Wasserman
  * @author Mike Bostock
  * @since 2.0
  */
 @GwtCompatible
-public final class HashBiMap<K, V> extends AbstractMap<K, V> implements BiMap<K, V>, Serializable {
+@ElementTypesAreNonnullByDefault
+public final class HashBiMap<K extends @Nullable Object, V extends @Nullable Object>
+    extends AbstractMap<K, V> implements BiMap<K, V>, Serializable {
 
   /** Returns a new, empty {@code HashBiMap} with the default initial capacity (16). */
-  public static <K, V> HashBiMap<K, V> create() {
+  public static <K extends @Nullable Object, V extends @Nullable Object> HashBiMap<K, V> create() {
     return create(16);
   }
 
@@ -63,7 +68,8 @@ public static <K, V> HashBiMap<K, V> create() {
    * @param expectedSize the expected number of entries
    * @throws IllegalArgumentException if the specified expected size is negative
    */
-  public static <K, V> HashBiMap<K, V> create(int expectedSize) {
+  public static <K extends @Nullable Object, V extends @Nullable Object> HashBiMap<K, V> create(
+      int expectedSize) {
     return new HashBiMap<>(expectedSize);
   }
 
@@ -71,7 +77,8 @@ public static <K, V> HashBiMap<K, V> create(int expectedSize) {
    * Constructs a new bimap containing initial values from {@code map}. The bimap is created with an
    * initial capacity sufficient to hold the mappings in the specified map.
    */
-  public static <K, V> HashBiMap<K, V> create(Map<? extends K, ? extends V> map) {
+  public static <K extends @Nullable Object, V extends @Nullable Object> HashBiMap<K, V> create(
+      Map<? extends K, ? extends V> map) {
     HashBiMap<K, V> bimap = create(map.size());
     bimap.putAll(map);
     return bimap;
@@ -81,9 +88,9 @@ public static <K, V> HashBiMap<K, V> create(Map<? extends K, ? extends V> map) {
   private static final int ENDPOINT = -2;
 
   /** Maps an "entry" to the key of that entry. */
-  transient K[] keys;
+  transient @Nullable K[] keys;
   /** Maps an "entry" to the value of that entry. */
-  transient V[] values;
+  transient @Nullable V[] values;
 
   transient int size;
   transient int modCount;
@@ -96,9 +103,9 @@ public static <K, V> HashBiMap<K, V> create(Map<? extends K, ? extends V> map) {
   /** Maps an "entry" to the "entry" that follows it in its bucket. */
   private transient int[] nextInBucketVToK;
   /** The "entry" of the first element in insertion order. */
-  @NullableDecl private transient int firstInInsertionOrder;
+  private transient int firstInInsertionOrder;
   /** The "entry" of the last element in insertion order. */
-  @NullableDecl private transient int lastInInsertionOrder;
+  private transient int lastInInsertionOrder;
   /** Maps an "entry" to the "entry" that precedes it in insertion order. */
   private transient int[] prevInInsertionOrder;
   /** Maps an "entry" to the "entry" that follows it in insertion order. */
@@ -193,19 +200,19 @@ private int bucket(int hash) {
   }
 
   /** Given a key, returns the index of the entry in the tables, or ABSENT if not found. */
-  int findEntryByKey(@NullableDecl Object key) {
+  int findEntryByKey(@CheckForNull Object key) {
     return findEntryByKey(key, Hashing.smearedHash(key));
   }
 
   /**
    * Given a key and its hash, returns the index of the entry in the tables, or ABSENT if not found.
    */
-  int findEntryByKey(@NullableDecl Object key, int keyHash) {
+  int findEntryByKey(@CheckForNull Object key, int keyHash) {
     return findEntry(key, keyHash, hashTableKToV, nextInBucketKToV, keys);
   }
 
   /** Given a value, returns the index of the entry in the tables, or ABSENT if not found. */
-  int findEntryByValue(@NullableDecl Object value) {
+  int findEntryByValue(@CheckForNull Object value) {
     return findEntryByValue(value, Hashing.smearedHash(value));
   }
 
@@ -213,12 +220,16 @@ int findEntryByValue(@NullableDecl Object value) {
    * Given a value and its hash, returns the index of the entry in the tables, or ABSENT if not
    * found.
    */
-  int findEntryByValue(@NullableDecl Object value, int valueHash) {
+  int findEntryByValue(@CheckForNull Object value, int valueHash) {
     return findEntry(value, valueHash, hashTableVToK, nextInBucketVToK, values);
   }
 
   int findEntry(
-      @NullableDecl Object o, int oHash, int[] hashTable, int[] nextInBucket, Object[] array) {
+      @CheckForNull Object o,
+      int oHash,
+      int[] hashTable,
+      int[] nextInBucket,
+      @Nullable Object[] array) {
     for (int entry = hashTable[bucket(oHash)]; entry != ABSENT; entry = nextInBucket[entry]) {
       if (Objects.equal(array[entry], o)) {
         return entry;
@@ -228,7 +239,7 @@ int findEntry(
   }
 
   @Override
-  public boolean containsKey(@NullableDecl Object key) {
+  public boolean containsKey(@CheckForNull Object key) {
     return findEntryByKey(key) != ABSENT;
   }
 
@@ -243,31 +254,32 @@ public boolean containsKey(@NullableDecl Object key) {
    * @return true if a mapping exists from a key to the specified value
    */
   @Override
-  public boolean containsValue(@NullableDecl Object value) {
+  public boolean containsValue(@CheckForNull Object value) {
     return findEntryByValue(value) != ABSENT;
   }
 
   @Override
-  @NullableDecl
-  public V get(@NullableDecl Object key) {
+  @CheckForNull
+  public V get(@CheckForNull Object key) {
     int entry = findEntryByKey(key);
     return (entry == ABSENT) ? null : values[entry];
   }
 
-  @NullableDecl
-  K getInverse(@NullableDecl Object value) {
+  @CheckForNull
+  K getInverse(@CheckForNull Object value) {
     int entry = findEntryByValue(value);
     return (entry == ABSENT) ? null : keys[entry];
   }
 
   @Override
   @CanIgnoreReturnValue
-  public V put(@NullableDecl K key, @NullableDecl V value) {
+  @CheckForNull
+  public V put(@ParametricNullness K key, @ParametricNullness V value) {
     return put(key, value, false);
   }
 
-  @NullableDecl
-  V put(@NullableDecl K key, @NullableDecl V value, boolean force) {
+  @CheckForNull
+  V put(@ParametricNullness K key, @ParametricNullness V value, boolean force) {
     int keyHash = Hashing.smearedHash(key);
     int entryForKey = findEntryByKey(key, keyHash);
     if (entryForKey != ABSENT) {
@@ -306,13 +318,14 @@ V put(@NullableDecl K key, @NullableDecl V value, boolean force) {
 
   @Override
   @CanIgnoreReturnValue
-  @NullableDecl
-  public V forcePut(@NullableDecl K key, @NullableDecl V value) {
+  @CheckForNull
+  public V forcePut(@ParametricNullness K key, @ParametricNullness V value) {
     return put(key, value, true);
   }
 
-  @NullableDecl
-  K putInverse(@NullableDecl V value, @NullableDecl K key, boolean force) {
+  @CanIgnoreReturnValue
+  @CheckForNull
+  K putInverse(@ParametricNullness V value, @ParametricNullness K key, boolean force) {
     int valueHash = Hashing.smearedHash(value);
     int entryForValue = findEntryByValue(value, valueHash);
     if (entryForValue != ABSENT) {
@@ -457,7 +470,7 @@ private void deleteFromTableVToK(int entry, int valueHash) {
    * Updates the specified entry to point to the new value: removes the old value from the V-to-K
    * mapping and puts the new one in. The entry does not move in the insertion order of the bimap.
    */
-  private void replaceValueInEntry(int entry, @NullableDecl V newValue, boolean force) {
+  private void replaceValueInEntry(int entry, @ParametricNullness V newValue, boolean force) {
     checkArgument(entry != ABSENT);
     int newValueHash = Hashing.smearedHash(newValue);
     int newValueIndex = findEntryByValue(newValue, newValueHash);
@@ -482,7 +495,7 @@ private void replaceValueInEntry(int entry, @NullableDecl V newValue, boolean fo
    * mapping and puts the new one in. The entry is moved to the end of the insertion order, or to
    * the position of the new key if it was previously present.
    */
-  private void replaceKeyInEntry(int entry, @NullableDecl K newKey, boolean force) {
+  private void replaceKeyInEntry(int entry, @ParametricNullness K newKey, boolean force) {
     checkArgument(entry != ABSENT);
     int newKeyHash = Hashing.smearedHash(newKey);
     int newKeyIndex = findEntryByKey(newKey, newKeyHash);
@@ -528,27 +541,27 @@ private void replaceKeyInEntry(int entry, @NullableDecl K newKey, boolean force)
 
   @Override
   @CanIgnoreReturnValue
-  @NullableDecl
-  public V remove(@NullableDecl Object key) {
+  @CheckForNull
+  public V remove(@CheckForNull Object key) {
     int keyHash = Hashing.smearedHash(key);
     int entry = findEntryByKey(key, keyHash);
     if (entry == ABSENT) {
       return null;
     } else {
-      @NullableDecl V value = values[entry];
+      V value = values[entry];
       removeEntryKeyHashKnown(entry, keyHash);
       return value;
     }
   }
 
-  @NullableDecl
-  K removeInverse(@NullableDecl Object value) {
+  @CheckForNull
+  K removeInverse(@CheckForNull Object value) {
     int valueHash = Hashing.smearedHash(value);
     int entry = findEntryByValue(value, valueHash);
     if (entry == ABSENT) {
       return null;
     } else {
-      @NullableDecl K key = keys[entry];
+      K key = keys[entry];
       removeEntryValueHashKnown(entry, valueHash);
       return key;
     }
@@ -663,13 +676,16 @@ public void clear() {
   }
 
   /** Shared supertype of keySet, values, entrySet, and inverse.entrySet. */
-  abstract static class View<K, V, T> extends AbstractSet<T> {
+  abstract static class View<
+          K extends @Nullable Object, V extends @Nullable Object, T extends @Nullable Object>
+      extends AbstractSet<T> {
     final HashBiMap<K, V> biMap;
 
     View(HashBiMap<K, V> biMap) {
       this.biMap = biMap;
     }
 
+    @ParametricNullness
     abstract T forEntry(int entry);
 
     @Override
@@ -696,6 +712,7 @@ public boolean hasNext() {
         }
 
         @Override
+        @ParametricNullness
         public T next() {
           if (!hasNext()) {
             throw new NoSuchElementException();
@@ -746,17 +763,19 @@ final class KeySet extends View<K, V, K> {
     }
 
     @Override
+    @ParametricNullness
     K forEntry(int entry) {
-      return keys[entry];
+      // The cast is safe because we call forEntry only for indexes that contain entries.
+      return uncheckedCastNullableTToT(keys[entry]);
     }
 
     @Override
-    public boolean contains(@NullableDecl Object o) {
+    public boolean contains(@CheckForNull Object o) {
       return HashBiMap.this.containsKey(o);
     }
 
     @Override
-    public boolean remove(@NullableDecl Object o) {
+    public boolean remove(@CheckForNull Object o) {
       int oHash = Hashing.smearedHash(o);
       int entry = findEntryByKey(o, oHash);
       if (entry != ABSENT) {
@@ -782,17 +801,19 @@ final class ValueSet extends View<K, V, V> {
     }
 
     @Override
+    @ParametricNullness
     V forEntry(int entry) {
-      return values[entry];
+      // The cast is safe because we call forEntry only for indexes that contain entries.
+      return uncheckedCastNullableTToT(values[entry]);
     }
 
     @Override
-    public boolean contains(@NullableDecl Object o) {
+    public boolean contains(@CheckForNull Object o) {
       return HashBiMap.this.containsValue(o);
     }
 
     @Override
-    public boolean remove(@NullableDecl Object o) {
+    public boolean remove(@CheckForNull Object o) {
       int oHash = Hashing.smearedHash(o);
       int entry = findEntryByValue(o, oHash);
       if (entry != ABSENT) {
@@ -818,11 +839,11 @@ final class EntrySet extends View<K, V, Entry<K, V>> {
     }
 
     @Override
-    public boolean contains(@NullableDecl Object o) {
+    public boolean contains(@CheckForNull Object o) {
       if (o instanceof Entry) {
         Entry<?, ?> e = (Entry<?, ?>) o;
-        @NullableDecl Object k = e.getKey();
-        @NullableDecl Object v = e.getValue();
+        Object k = e.getKey();
+        Object v = e.getValue();
         int eIndex = findEntryByKey(k);
         return eIndex != ABSENT && Objects.equal(v, values[eIndex]);
       }
@@ -831,11 +852,11 @@ public boolean contains(@NullableDecl Object o) {
 
     @Override
     @CanIgnoreReturnValue
-    public boolean remove(@NullableDecl Object o) {
+    public boolean remove(@CheckForNull Object o) {
       if (o instanceof Entry) {
         Entry<?, ?> e = (Entry<?, ?>) o;
-        @NullableDecl Object k = e.getKey();
-        @NullableDecl Object v = e.getValue();
+        Object k = e.getKey();
+        Object v = e.getValue();
         int kHash = Hashing.smearedHash(k);
         int eIndex = findEntryByKey(k, kHash);
         if (eIndex != ABSENT && Objects.equal(v, values[eIndex])) {
@@ -855,14 +876,17 @@ Entry<K, V> forEntry(int entry) {
   /**
    * An {@code Entry} implementation that attempts to follow its key around the map -- that is, if
    * the key is moved, deleted, or reinserted, it will account for that -- while not doing any extra
-   * work if the key has not moved.
+   * work if the key has not moved. One quirk: The {@link #getValue()} method can return {@code
+   * null} even for a map which supposedly does not contain null elements, if the key is not present
+   * when {@code getValue()} is called.
    */
   final class EntryForKey extends AbstractMapEntry<K, V> {
-    @NullableDecl final K key;
+    @ParametricNullness final K key;
     int index;
 
     EntryForKey(int index) {
-      this.key = keys[index];
+      // The cast is safe because we call forEntry only for indexes that contain entries.
+      this.key = uncheckedCastNullableTToT(keys[index]);
       this.index = index;
     }
 
@@ -873,24 +897,43 @@ void updateIndex() {
     }
 
     @Override
+    @ParametricNullness
     public K getKey() {
       return key;
     }
 
     @Override
-    @NullableDecl
+    @ParametricNullness
     public V getValue() {
       updateIndex();
-      return (index == ABSENT) ? null : values[index];
+      /*
+       * If the entry has been removed from the map, we return null, even though that might not be a
+       * valid value. That's the best we can do, short of holding a reference to the most recently
+       * seen value. And while we *could* do that, we aren't required to: Map.Entry explicitly says
+       * that behavior is undefined when the backing map is modified through another API. (It even
+       * permits us to throw IllegalStateException. Maybe we should have done that, but we probably
+       * shouldn't change now for fear of breaking people.)
+       *
+       * If the entry is still in the map, then updateIndex ensured that `index` points to the right
+       * element. Because that element is present, uncheckedCastNullableTToT is safe.
+       */
+      return (index == ABSENT) ? unsafeNull() : uncheckedCastNullableTToT(values[index]);
     }
 
     @Override
-    public V setValue(V value) {
+    @ParametricNullness
+    public V setValue(@ParametricNullness V value) {
       updateIndex();
       if (index == ABSENT) {
-        return HashBiMap.this.put(key, value);
+        HashBiMap.this.put(key, value);
+        return unsafeNull(); // See the discussion in getValue().
       }
-      V oldValue = values[index];
+      /*
+       * The cast is safe because updateIndex found the entry for this key. (If it hadn't, then we
+       * would have returned above.) Thus, we know that it and its corresponding value are in
+       * position `index`.
+       */
+      V oldValue = uncheckedCastNullableTToT(values[index]);
       if (Objects.equal(oldValue, value)) {
         return value;
       }
@@ -899,7 +942,7 @@ public V setValue(V value) {
     }
   }
 
-  @LazyInit @RetainedWith @NullableDecl private transient BiMap<V, K> inverse;
+  @LazyInit @RetainedWith @CheckForNull private transient BiMap<V, K> inverse;
 
   @Override
   public BiMap<V, K> inverse() {
@@ -907,7 +950,8 @@ public BiMap<V, K> inverse() {
     return (result == null) ? inverse = new Inverse<K, V>(this) : result;
   }
 
-  static class Inverse<K, V> extends AbstractMap<V, K> implements BiMap<V, K>, Serializable {
+  static class Inverse<K extends @Nullable Object, V extends @Nullable Object>
+      extends AbstractMap<V, K> implements BiMap<V, K>, Serializable {
     private final HashBiMap<K, V> forward;
 
     Inverse(HashBiMap<K, V> forward) {
@@ -920,32 +964,32 @@ public int size() {
     }
 
     @Override
-    public boolean containsKey(@NullableDecl Object key) {
+    public boolean containsKey(@CheckForNull Object key) {
       return forward.containsValue(key);
     }
 
     @Override
-    @NullableDecl
-    public K get(@NullableDecl Object key) {
+    @CheckForNull
+    public K get(@CheckForNull Object key) {
       return forward.getInverse(key);
     }
 
     @Override
-    public boolean containsValue(@NullableDecl Object value) {
+    public boolean containsValue(@CheckForNull Object value) {
       return forward.containsKey(value);
     }
 
     @Override
     @CanIgnoreReturnValue
-    @NullableDecl
-    public K put(@NullableDecl V value, @NullableDecl K key) {
+    @CheckForNull
+    public K put(@ParametricNullness V value, @ParametricNullness K key) {
       return forward.putInverse(value, key, false);
     }
 
     @Override
     @CanIgnoreReturnValue
-    @NullableDecl
-    public K forcePut(@NullableDecl V value, @NullableDecl K key) {
+    @CheckForNull
+    public K forcePut(@ParametricNullness V value, @ParametricNullness K key) {
       return forward.putInverse(value, key, true);
     }
 
@@ -956,8 +1000,8 @@ public BiMap<K, V> inverse() {
 
     @Override
     @CanIgnoreReturnValue
-    @NullableDecl
-    public K remove(@NullableDecl Object value) {
+    @CheckForNull
+    public K remove(@CheckForNull Object value) {
       return forward.removeInverse(value);
     }
 
@@ -991,13 +1035,14 @@ private void readObject(ObjectInputStream in) throws ClassNotFoundException, IOE
     }
   }
 
-  static class InverseEntrySet<K, V> extends View<K, V, Entry<V, K>> {
+  static class InverseEntrySet<K extends @Nullable Object, V extends @Nullable Object>
+      extends View<K, V, Entry<V, K>> {
     InverseEntrySet(HashBiMap<K, V> biMap) {
       super(biMap);
     }
 
     @Override
-    public boolean contains(@NullableDecl Object o) {
+    public boolean contains(@CheckForNull Object o) {
       if (o instanceof Entry) {
         Entry<?, ?> e = (Entry<?, ?>) o;
         Object v = e.getKey();
@@ -1009,7 +1054,7 @@ public boolean contains(@NullableDecl Object o) {
     }
 
     @Override
-    public boolean remove(Object o) {
+    public boolean remove(@CheckForNull Object o) {
       if (o instanceof Entry) {
         Entry<?, ?> e = (Entry<?, ?>) o;
         Object v = e.getKey();
@@ -1035,14 +1080,16 @@ Entry<V, K> forEntry(int entry) {
    * the value is moved, deleted, or reinserted, it will account for that -- while not doing any
    * extra work if the value has not moved.
    */
-  static final class EntryForValue<K, V> extends AbstractMapEntry<V, K> {
+  static final class EntryForValue<K extends @Nullable Object, V extends @Nullable Object>
+      extends AbstractMapEntry<V, K> {
     final HashBiMap<K, V> biMap;
-    final V value;
+    @ParametricNullness final V value;
     int index;
 
     EntryForValue(HashBiMap<K, V> biMap, int index) {
       this.biMap = biMap;
-      this.value = biMap.values[index];
+      // The cast is safe because we call forEntry only for indexes that contain entries.
+      this.value = uncheckedCastNullableTToT(biMap.values[index]);
       this.index = index;
     }
 
@@ -1053,23 +1100,28 @@ private void updateIndex() {
     }
 
     @Override
+    @ParametricNullness
     public V getKey() {
       return value;
     }
 
     @Override
+    @ParametricNullness
     public K getValue() {
       updateIndex();
-      return (index == ABSENT) ? null : biMap.keys[index];
+      // For discussion of unsafeNull() and uncheckedCastNullableTToT(), see EntryForKey.getValue().
+      return (index == ABSENT) ? unsafeNull() : uncheckedCastNullableTToT(biMap.keys[index]);
     }
 
     @Override
-    public K setValue(K key) {
+    @ParametricNullness
+    public K setValue(@ParametricNullness K key) {
       updateIndex();
       if (index == ABSENT) {
-        return biMap.putInverse(value, key, false);
+        biMap.putInverse(value, key, false);
+        return unsafeNull(); // see EntryForKey.setValue()
       }
-      K oldKey = biMap.keys[index];
+      K oldKey = uncheckedCastNullableTToT(biMap.keys[index]); // see EntryForKey.setValue()
       if (Objects.equal(oldKey, key)) {
         return key;
       }
diff --git a/android/guava/src/com/google/common/collect/HashMultimap.java b/android/guava/src/com/google/common/collect/HashMultimap.java
index 92972608ecde..9e4c1c2233f1 100644
--- a/android/guava/src/com/google/common/collect/HashMultimap.java
+++ b/android/guava/src/com/google/common/collect/HashMultimap.java
@@ -26,6 +26,7 @@
 import java.util.Collection;
 import java.util.Map;
 import java.util.Set;
+import org.checkerframework.checker.nullness.qual.Nullable;
 
 /**
  * Implementation of {@link Multimap} using hash tables.
@@ -41,11 +42,16 @@
  * concurrent update operations, wrap your multimap with a call to {@link
  * Multimaps#synchronizedSetMultimap}.
  *
+ * <p><b>Warning:</b> Do not modify either a key <i>or a value</i> of a {@code HashMultimap} in a
+ * way that affects its {@link Object#equals} behavior. Undefined behavior and bugs will result.
+ *
  * @author Jared Levy
  * @since 2.0
  */
 @GwtCompatible(serializable = true, emulated = true)
-public final class HashMultimap<K, V> extends HashMultimapGwtSerializationDependencies<K, V> {
+@ElementTypesAreNonnullByDefault
+public final class HashMultimap<K extends @Nullable Object, V extends @Nullable Object>
+    extends HashMultimapGwtSerializationDependencies<K, V> {
   private static final int DEFAULT_VALUES_PER_KEY = 2;
 
   @VisibleForTesting transient int expectedValuesPerKey = DEFAULT_VALUES_PER_KEY;
@@ -56,7 +62,8 @@ public final class HashMultimap<K, V> extends HashMultimapGwtSerializationDepend
    * <p>This method will soon be deprecated in favor of {@code
    * MultimapBuilder.hashKeys().hashSetValues().build()}.
    */
-  public static <K, V> HashMultimap<K, V> create() {
+  public static <K extends @Nullable Object, V extends @Nullable Object>
+      HashMultimap<K, V> create() {
     return new HashMultimap<>();
   }
 
@@ -72,7 +79,8 @@ public static <K, V> HashMultimap<K, V> create() {
    * @throws IllegalArgumentException if {@code expectedKeys} or {@code expectedValuesPerKey} is
    *     negative
    */
-  public static <K, V> HashMultimap<K, V> create(int expectedKeys, int expectedValuesPerKey) {
+  public static <K extends @Nullable Object, V extends @Nullable Object> HashMultimap<K, V> create(
+      int expectedKeys, int expectedValuesPerKey) {
     return new HashMultimap<>(expectedKeys, expectedValuesPerKey);
   }
 
@@ -86,7 +94,8 @@ public static <K, V> HashMultimap<K, V> create(int expectedKeys, int expectedVal
    *
    * @param multimap the multimap whose contents are copied to this multimap
    */
-  public static <K, V> HashMultimap<K, V> create(Multimap<? extends K, ? extends V> multimap) {
+  public static <K extends @Nullable Object, V extends @Nullable Object> HashMultimap<K, V> create(
+      Multimap<? extends K, ? extends V> multimap) {
     return new HashMultimap<>(multimap);
   }
 
diff --git a/android/guava/src/com/google/common/collect/HashMultiset.java b/android/guava/src/com/google/common/collect/HashMultiset.java
index a78c6915e26c..0748e68be4d9 100644
--- a/android/guava/src/com/google/common/collect/HashMultiset.java
+++ b/android/guava/src/com/google/common/collect/HashMultiset.java
@@ -18,6 +18,7 @@
 
 import com.google.common.annotations.GwtCompatible;
 import com.google.common.annotations.GwtIncompatible;
+import org.checkerframework.checker.nullness.qual.Nullable;
 
 /**
  * Multiset implementation that uses hashing for key and entry access.
@@ -27,10 +28,11 @@
  * @since 2.0
  */
 @GwtCompatible(serializable = true, emulated = true)
-public class HashMultiset<E> extends AbstractMapBasedMultiset<E> {
+@ElementTypesAreNonnullByDefault
+public final class HashMultiset<E extends @Nullable Object> extends AbstractMapBasedMultiset<E> {
 
   /** Creates a new, empty {@code HashMultiset} using the default initial capacity. */
-  public static <E> HashMultiset<E> create() {
+  public static <E extends @Nullable Object> HashMultiset<E> create() {
     return create(ObjectCountHashMap.DEFAULT_SIZE);
   }
 
@@ -41,7 +43,7 @@ public static <E> HashMultiset<E> create() {
    * @param distinctElements the expected number of distinct elements
    * @throws IllegalArgumentException if {@code distinctElements} is negative
    */
-  public static <E> HashMultiset<E> create(int distinctElements) {
+  public static <E extends @Nullable Object> HashMultiset<E> create(int distinctElements) {
     return new HashMultiset<E>(distinctElements);
   }
 
@@ -52,7 +54,8 @@ public static <E> HashMultiset<E> create(int distinctElements) {
    *
    * @param elements the elements that the multiset should contain
    */
-  public static <E> HashMultiset<E> create(Iterable<? extends E> elements) {
+  public static <E extends @Nullable Object> HashMultiset<E> create(
+      Iterable<? extends E> elements) {
     HashMultiset<E> multiset = create(Multisets.inferDistinctElements(elements));
     Iterables.addAll(multiset, elements);
     return multiset;
@@ -63,8 +66,8 @@ public static <E> HashMultiset<E> create(Iterable<? extends E> elements) {
   }
 
   @Override
-  void init(int distinctElements) {
-    backingMap = new ObjectCountHashMap<>(distinctElements);
+  ObjectCountHashMap<E> newBackingMap(int distinctElements) {
+    return new ObjectCountHashMap<>(distinctElements);
   }
 
   @GwtIncompatible // Not needed in emulated source.
diff --git a/android/guava/src/com/google/common/collect/Hashing.java b/android/guava/src/com/google/common/collect/Hashing.java
index d5cab1faf1e0..81ef67ebbc76 100644
--- a/android/guava/src/com/google/common/collect/Hashing.java
+++ b/android/guava/src/com/google/common/collect/Hashing.java
@@ -18,7 +18,7 @@
 
 import com.google.common.annotations.GwtCompatible;
 import com.google.common.primitives.Ints;
-import org.checkerframework.checker.nullness.compatqual.NullableDecl;
+import javax.annotation.CheckForNull;
 
 /**
  * Static methods for implementing hash-based collections.
@@ -28,6 +28,7 @@
  * @author Austin Appleby
  */
 @GwtCompatible
+@ElementTypesAreNonnullByDefault
 final class Hashing {
   private Hashing() {}
 
@@ -50,7 +51,7 @@ static int smear(int hashCode) {
     return (int) (C2 * Integer.rotateLeft((int) (hashCode * C1), 15));
   }
 
-  static int smearedHash(@NullableDecl Object o) {
+  static int smearedHash(@CheckForNull Object o) {
     return smear((o == null) ? 0 : o.hashCode());
   }
 
diff --git a/android/guava/src/com/google/common/collect/ImmutableAsList.java b/android/guava/src/com/google/common/collect/ImmutableAsList.java
index 528a8dca1f85..c39747931796 100644
--- a/android/guava/src/com/google/common/collect/ImmutableAsList.java
+++ b/android/guava/src/com/google/common/collect/ImmutableAsList.java
@@ -21,6 +21,7 @@
 import java.io.InvalidObjectException;
 import java.io.ObjectInputStream;
 import java.io.Serializable;
+import javax.annotation.CheckForNull;
 
 /**
  * List returned by {@link ImmutableCollection#asList} that delegates {@code contains} checks to the
@@ -31,11 +32,12 @@
  */
 @GwtCompatible(serializable = true, emulated = true)
 @SuppressWarnings("serial")
+@ElementTypesAreNonnullByDefault
 abstract class ImmutableAsList<E> extends ImmutableList<E> {
   abstract ImmutableCollection<E> delegateCollection();
 
   @Override
-  public boolean contains(Object target) {
+  public boolean contains(@CheckForNull Object target) {
     // The collection's contains() is at least as fast as ImmutableList's
     // and is often faster.
     return delegateCollection().contains(target);
diff --git a/android/guava/src/com/google/common/collect/ImmutableBiMap.java b/android/guava/src/com/google/common/collect/ImmutableBiMap.java
index ed7559fcc494..1de5bd10f073 100644
--- a/android/guava/src/com/google/common/collect/ImmutableBiMap.java
+++ b/android/guava/src/com/google/common/collect/ImmutableBiMap.java
@@ -23,9 +23,11 @@
 import com.google.common.annotations.GwtCompatible;
 import com.google.errorprone.annotations.CanIgnoreReturnValue;
 import com.google.errorprone.annotations.DoNotCall;
+import java.util.Arrays;
 import java.util.Collection;
 import java.util.Comparator;
 import java.util.Map;
+import javax.annotation.CheckForNull;
 
 /**
  * A {@link BiMap} whose contents will never change, with many other important properties detailed
@@ -35,9 +37,14 @@
  * @since 2.0
  */
 @GwtCompatible(serializable = true, emulated = true)
+@ElementTypesAreNonnullByDefault
 public abstract class ImmutableBiMap<K, V> extends ImmutableMap<K, V> implements BiMap<K, V> {
 
-  /** Returns the empty bimap. */
+  /**
+   * Returns the empty bimap.
+   *
+   * <p><b>Performance note:</b> the instance returned is a singleton.
+   */
   // Casting to any type is safe because the set will never hold any elements.
   @SuppressWarnings("unchecked")
   public static <K, V> ImmutableBiMap<K, V> of() {
@@ -102,7 +109,170 @@ public static <K, V> ImmutableBiMap<K, V> of(
         new Object[] {k1, v1, k2, v2, k3, v3, k4, v4, k5, v5}, 5);
   }
 
-  // looking for of() with > 5 entries? Use the builder instead.
+  /**
+   * Returns an immutable map containing the given entries, in order.
+   *
+   * @throws IllegalArgumentException if duplicate keys or values are added
+   * @since 31.0
+   */
+  public static <K, V> ImmutableBiMap<K, V> of(
+      K k1, V v1, K k2, V v2, K k3, V v3, K k4, V v4, K k5, V v5, K k6, V v6) {
+    checkEntryNotNull(k1, v1);
+    checkEntryNotNull(k2, v2);
+    checkEntryNotNull(k3, v3);
+    checkEntryNotNull(k4, v4);
+    checkEntryNotNull(k5, v5);
+    checkEntryNotNull(k6, v6);
+    return new RegularImmutableBiMap<K, V>(
+        new Object[] {k1, v1, k2, v2, k3, v3, k4, v4, k5, v5, k6, v6}, 6);
+  }
+  /**
+   * Returns an immutable map containing the given entries, in order.
+   *
+   * @throws IllegalArgumentException if duplicate keys or values are added
+   * @since 31.0
+   */
+  public static <K, V> ImmutableBiMap<K, V> of(
+      K k1, V v1, K k2, V v2, K k3, V v3, K k4, V v4, K k5, V v5, K k6, V v6, K k7, V v7) {
+    checkEntryNotNull(k1, v1);
+    checkEntryNotNull(k2, v2);
+    checkEntryNotNull(k3, v3);
+    checkEntryNotNull(k4, v4);
+    checkEntryNotNull(k5, v5);
+    checkEntryNotNull(k6, v6);
+    checkEntryNotNull(k7, v7);
+    return new RegularImmutableBiMap<K, V>(
+        new Object[] {k1, v1, k2, v2, k3, v3, k4, v4, k5, v5, k6, v6, k7, v7}, 7);
+  }
+  /**
+   * Returns an immutable map containing the given entries, in order.
+   *
+   * @throws IllegalArgumentException if duplicate keys or values are added
+   * @since 31.0
+   */
+  public static <K, V> ImmutableBiMap<K, V> of(
+      K k1,
+      V v1,
+      K k2,
+      V v2,
+      K k3,
+      V v3,
+      K k4,
+      V v4,
+      K k5,
+      V v5,
+      K k6,
+      V v6,
+      K k7,
+      V v7,
+      K k8,
+      V v8) {
+    checkEntryNotNull(k1, v1);
+    checkEntryNotNull(k2, v2);
+    checkEntryNotNull(k3, v3);
+    checkEntryNotNull(k4, v4);
+    checkEntryNotNull(k5, v5);
+    checkEntryNotNull(k6, v6);
+    checkEntryNotNull(k7, v7);
+    checkEntryNotNull(k8, v8);
+    return new RegularImmutableBiMap<K, V>(
+        new Object[] {k1, v1, k2, v2, k3, v3, k4, v4, k5, v5, k6, v6, k7, v7, k8, v8}, 8);
+  }
+  /**
+   * Returns an immutable map containing the given entries, in order.
+   *
+   * @throws IllegalArgumentException if duplicate keys or values are added
+   * @since 31.0
+   */
+  public static <K, V> ImmutableBiMap<K, V> of(
+      K k1,
+      V v1,
+      K k2,
+      V v2,
+      K k3,
+      V v3,
+      K k4,
+      V v4,
+      K k5,
+      V v5,
+      K k6,
+      V v6,
+      K k7,
+      V v7,
+      K k8,
+      V v8,
+      K k9,
+      V v9) {
+    checkEntryNotNull(k1, v1);
+    checkEntryNotNull(k2, v2);
+    checkEntryNotNull(k3, v3);
+    checkEntryNotNull(k4, v4);
+    checkEntryNotNull(k5, v5);
+    checkEntryNotNull(k6, v6);
+    checkEntryNotNull(k7, v7);
+    checkEntryNotNull(k8, v8);
+    checkEntryNotNull(k9, v9);
+    return new RegularImmutableBiMap<K, V>(
+        new Object[] {k1, v1, k2, v2, k3, v3, k4, v4, k5, v5, k6, v6, k7, v7, k8, v8, k9, v9}, 9);
+  }
+  /**
+   * Returns an immutable map containing the given entries, in order.
+   *
+   * @throws IllegalArgumentException if duplicate keys or values are added
+   * @since 31.0
+   */
+  public static <K, V> ImmutableBiMap<K, V> of(
+      K k1,
+      V v1,
+      K k2,
+      V v2,
+      K k3,
+      V v3,
+      K k4,
+      V v4,
+      K k5,
+      V v5,
+      K k6,
+      V v6,
+      K k7,
+      V v7,
+      K k8,
+      V v8,
+      K k9,
+      V v9,
+      K k10,
+      V v10) {
+    checkEntryNotNull(k1, v1);
+    checkEntryNotNull(k2, v2);
+    checkEntryNotNull(k3, v3);
+    checkEntryNotNull(k4, v4);
+    checkEntryNotNull(k5, v5);
+    checkEntryNotNull(k6, v6);
+    checkEntryNotNull(k7, v7);
+    checkEntryNotNull(k8, v8);
+    checkEntryNotNull(k9, v9);
+    checkEntryNotNull(k10, v10);
+    return new RegularImmutableBiMap<K, V>(
+        new Object[] {
+          k1, v1, k2, v2, k3, v3, k4, v4, k5, v5, k6, v6, k7, v7, k8, v8, k9, v9, k10, v10
+        },
+        10);
+  }
+
+  // looking for of() with > 10 entries? Use the builder or ofEntries instead.
+
+  /**
+   * Returns an immutable map containing the given entries, in order.
+   *
+   * @throws IllegalArgumentException if duplicate keys or values are provided
+   * @since 31.0
+   */
+  @SafeVarargs
+  public static <K, V> ImmutableBiMap<K, V> ofEntries(Entry<? extends K, ? extends V>... entries) {
+    @SuppressWarnings("unchecked") // we will only ever read these
+    Entry<K, V>[] entries2 = (Entry<K, V>[]) entries;
+    return copyOf(Arrays.asList(entries2));
+  }
 
   /**
    * Returns a new builder. The generated builder is equivalent to the builder created by the {@link
@@ -140,7 +310,7 @@ public static <K, V> Builder<K, V> builderWithExpectedSize(int expectedSize) {
    *         .put("one", 1)
    *         .put("two", 2)
    *         .put("three", 3)
-   *         .build();
+   *         .buildOrThrow();
    * }</pre>
    *
    * <p>For <i>small</i> immutable bimaps, the {@code ImmutableBiMap.of()} methods are even more
@@ -153,8 +323,8 @@ public static <K, V> Builder<K, V> builderWithExpectedSize(int expectedSize) {
    * want a different order, consider using {@link #orderEntriesByValue(Comparator)}, which changes
    * this builder to sort entries by value.
    *
-   * <p>Builder instances can be reused - it is safe to call {@link #build} multiple times to build
-   * multiple bimaps in series. Each bimap is a superset of the bimaps created before it.
+   * <p>Builder instances can be reused - it is safe to call {@link #buildOrThrow} multiple times to
+   * build multiple bimaps in series. Each bimap is a superset of the bimaps created before it.
    *
    * @since 2.0
    */
@@ -253,17 +423,55 @@ Builder<K, V> combine(ImmutableMap.Builder<K, V> builder) {
      * order in which entries were inserted into the builder, unless {@link #orderEntriesByValue}
      * was called, in which case entries are sorted by value.
      *
+     * <p>Prefer the equivalent method {@link #buildOrThrow()} to make it explicit that the method
+     * will throw an exception if there are duplicate keys or values. The {@code build()} method
+     * will soon be deprecated.
+     *
      * @throws IllegalArgumentException if duplicate keys or values were added
      */
     @Override
     public ImmutableBiMap<K, V> build() {
+      return buildOrThrow();
+    }
+
+    /**
+     * Returns a newly-created immutable bimap, or throws an exception if any key or value was added
+     * more than once. The iteration order of the returned bimap is the order in which entries were
+     * inserted into the builder, unless {@link #orderEntriesByValue} was called, in which case
+     * entries are sorted by value.
+     *
+     * @throws IllegalArgumentException if duplicate keys or values were added
+     * @since 31.0
+     */
+    @Override
+    public ImmutableBiMap<K, V> buildOrThrow() {
       if (size == 0) {
         return of();
       }
-      sortEntries();
+      if (valueComparator != null) {
+        if (entriesUsed) {
+          alternatingKeysAndValues = Arrays.copyOf(alternatingKeysAndValues, 2 * size);
+        }
+        sortEntries(alternatingKeysAndValues, size, valueComparator);
+      }
       entriesUsed = true;
       return new RegularImmutableBiMap<K, V>(alternatingKeysAndValues, size);
     }
+
+    /**
+     * Throws {@link UnsupportedOperationException}. This method is inherited from {@link
+     * ImmutableMap.Builder}, but it does not make sense for bimaps.
+     *
+     * @throws UnsupportedOperationException always
+     * @deprecated This method does not make sense for bimaps and should not be called.
+     * @since 31.1
+     */
+    @DoNotCall
+    @Deprecated
+    @Override
+    public ImmutableBiMap<K, V> buildKeepingLast() {
+      throw new UnsupportedOperationException("Not supported for bimaps");
+    }
   }
 
   /**
@@ -348,6 +556,7 @@ final ImmutableSet<V> createValues() {
   @Deprecated
   @Override
   @DoNotCall("Always throws UnsupportedOperationException")
+  @CheckForNull
   public final V forcePut(K key, V value) {
     throw new UnsupportedOperationException();
   }
diff --git a/android/guava/src/com/google/common/collect/ImmutableClassToInstanceMap.java b/android/guava/src/com/google/common/collect/ImmutableClassToInstanceMap.java
index 21691d2ff19d..c59e9fdaba8e 100644
--- a/android/guava/src/com/google/common/collect/ImmutableClassToInstanceMap.java
+++ b/android/guava/src/com/google/common/collect/ImmutableClassToInstanceMap.java
@@ -25,7 +25,7 @@
 import com.google.errorprone.annotations.Immutable;
 import java.io.Serializable;
 import java.util.Map;
-import org.checkerframework.checker.nullness.compatqual.NullableDecl;
+import javax.annotation.CheckForNull;
 
 /**
  * A {@link ClassToInstanceMap} whose contents will never change, with many other important
@@ -36,6 +36,7 @@
  */
 @Immutable(containerOf = "B")
 @GwtIncompatible
+@ElementTypesAreNonnullByDefault
 public final class ImmutableClassToInstanceMap<B> extends ForwardingMap<Class<? extends B>, B>
     implements ClassToInstanceMap<B>, Serializable {
 
@@ -45,6 +46,8 @@ public final class ImmutableClassToInstanceMap<B> extends ForwardingMap<Class<?
   /**
    * Returns an empty {@code ImmutableClassToInstanceMap}.
    *
+   * <p><b>Performance note:</b> the instance returned is a singleton.
+   *
    * @since 19.0
    */
   @SuppressWarnings("unchecked")
@@ -59,7 +62,7 @@ public static <B> ImmutableClassToInstanceMap<B> of() {
    */
   public static <B, T extends B> ImmutableClassToInstanceMap<B> of(Class<T> type, T value) {
     ImmutableMap<Class<? extends B>, B> map = ImmutableMap.<Class<? extends B>, B>of(type, value);
-    return new ImmutableClassToInstanceMap<B>(map);
+    return new ImmutableClassToInstanceMap<>(map);
   }
 
   /**
@@ -67,7 +70,7 @@ public static <B, T extends B> ImmutableClassToInstanceMap<B> of(Class<T> type,
    * Builder} constructor.
    */
   public static <B> Builder<B> builder() {
-    return new Builder<B>();
+    return new Builder<>();
   }
 
   /**
@@ -128,11 +131,11 @@ private static <B, T extends B> T cast(Class<T> type, B value) {
      * @throws IllegalArgumentException if duplicate keys were added
      */
     public ImmutableClassToInstanceMap<B> build() {
-      ImmutableMap<Class<? extends B>, B> map = mapBuilder.build();
+      ImmutableMap<Class<? extends B>, B> map = mapBuilder.buildOrThrow();
       if (map.isEmpty()) {
         return of();
       } else {
-        return new ImmutableClassToInstanceMap<B>(map);
+        return new ImmutableClassToInstanceMap<>(map);
       }
     }
   }
@@ -171,7 +174,7 @@ protected Map<Class<? extends B>, B> delegate() {
 
   @Override
   @SuppressWarnings("unchecked") // value could not get in if not a T
-  @NullableDecl
+  @CheckForNull
   public <T extends B> T getInstance(Class<T> type) {
     return (T) delegate.get(checkNotNull(type));
   }
@@ -186,6 +189,7 @@ public <T extends B> T getInstance(Class<T> type) {
   @Deprecated
   @Override
   @DoNotCall("Always throws UnsupportedOperationException")
+  @CheckForNull
   public <T extends B> T putInstance(Class<T> type, T value) {
     throw new UnsupportedOperationException();
   }
diff --git a/android/guava/src/com/google/common/collect/ImmutableCollection.java b/android/guava/src/com/google/common/collect/ImmutableCollection.java
index 23d9eca944b0..d5420e040100 100644
--- a/android/guava/src/com/google/common/collect/ImmutableCollection.java
+++ b/android/guava/src/com/google/common/collect/ImmutableCollection.java
@@ -32,7 +32,8 @@
 import java.util.HashSet;
 import java.util.Iterator;
 import java.util.List;
-import org.checkerframework.checker.nullness.compatqual.NullableDecl;
+import javax.annotation.CheckForNull;
+import org.checkerframework.checker.nullness.qual.Nullable;
 
 /**
  * A {@link Collection} whose contents will never change, and which offers a few additional
@@ -155,13 +156,14 @@
  * <h3>See also</h3>
  *
  * <p>See the Guava User Guide article on <a href=
- * "https://github.com/google/guava/wiki/ImmutableCollectionsExplained"> immutable collections</a>.
+ * "https://github.com/google/guava/wiki/ImmutableCollectionsExplained">immutable collections</a>.
  *
  * @since 2.0
  */
 @DoNotMock("Use ImmutableList.of or another implementation")
 @GwtCompatible(emulated = true)
 @SuppressWarnings("serial") // we're overriding default serialization
+@ElementTypesAreNonnullByDefault
 // TODO(kevinb): I think we should push everything down to "BaseImmutableCollection" or something,
 // just to do everything we can to emphasize the "practically an interface" nature of this class.
 public abstract class ImmutableCollection<E> extends AbstractCollection<E> implements Serializable {
@@ -181,7 +183,20 @@ public final Object[] toArray() {
 
   @CanIgnoreReturnValue
   @Override
-  public final <T> T[] toArray(T[] other) {
+  /*
+   * This suppression is here for two reasons:
+   *
+   * 1. b/192354773 in our checker affects toArray declarations.
+   *
+   * 2. `other[size] = null` is unsound. We could "fix" this by requiring callers to pass in an
+   * array with a nullable element type. But probably they usually want an array with a non-nullable
+   * type. That said, we could *accept* a `@Nullable T[]` (which, given that we treat arrays as
+   * covariant, would still permit a plain `T[]`) and return a plain `T[]`. But of course that would
+   * require its own suppression, since it is also unsound. toArray(T[]) is just a mess from a
+   * nullness perspective. The signature below at least has the virtue of being relatively simple.
+   */
+  @SuppressWarnings("nullness")
+  public final <T extends @Nullable Object> T[] toArray(T[] other) {
     checkNotNull(other);
     int size = size();
 
@@ -199,7 +214,8 @@ public final <T> T[] toArray(T[] other) {
   }
 
   /** If this collection is backed by an array of its elements in insertion order, returns it. */
-  @NullableDecl
+  @CheckForNull
+  @Nullable
   Object[] internalArray() {
     return null;
   }
@@ -221,7 +237,7 @@ int internalArrayEnd() {
   }
 
   @Override
-  public abstract boolean contains(@NullableDecl Object object);
+  public abstract boolean contains(@CheckForNull Object object);
 
   /**
    * Guaranteed to throw an exception and leave the collection unmodified.
@@ -247,7 +263,7 @@ public final boolean add(E e) {
   @Deprecated
   @Override
   @DoNotCall("Always throws UnsupportedOperationException")
-  public final boolean remove(Object object) {
+  public final boolean remove(@CheckForNull Object object) {
     throw new UnsupportedOperationException();
   }
 
@@ -333,7 +349,7 @@ public ImmutableList<E> asList() {
    * offset. Returns {@code offset + size()}.
    */
   @CanIgnoreReturnValue
-  int copyIntoArray(Object[] dst, int offset) {
+  int copyIntoArray(@Nullable Object[] dst, int offset) {
     for (E e : this) {
       dst[offset++] = e;
     }
@@ -449,13 +465,14 @@ public Builder<E> addAll(Iterator<? extends E> elements) {
   }
 
   abstract static class ArrayBasedBuilder<E> extends ImmutableCollection.Builder<E> {
-    Object[] contents;
+    // The first `size` elements are non-null.
+    @Nullable Object[] contents;
     int size;
     boolean forceCopy;
 
     ArrayBasedBuilder(int initialCapacity) {
       checkNonnegative(initialCapacity, "initialCapacity");
-      this.contents = new Object[initialCapacity];
+      this.contents = new @Nullable Object[initialCapacity];
       this.size = 0;
     }
 
@@ -491,9 +508,17 @@ public Builder<E> add(E... elements) {
       return this;
     }
 
-    final void addAll(Object[] elements, int n) {
+    final void addAll(@Nullable Object[] elements, int n) {
       checkElementsNotNull(elements, n);
       getReadyToExpandTo(size + n);
+      /*
+       * The following call is not statically checked, since arraycopy accepts plain Object for its
+       * parameters. If it were statically checked, the checker would still be OK with it, since
+       * we're copying into a `contents` array whose type allows it to contain nulls. Still, it's
+       * worth noting that we promise not to put nulls into the array in the first `size` elements.
+       * We uphold that promise here because our callers promise that `elements` will not contain
+       * nulls in its first `n` elements.
+       */
       System.arraycopy(elements, 0, contents, size, n);
       size += n;
     }
diff --git a/android/guava/src/com/google/common/collect/ImmutableEntry.java b/android/guava/src/com/google/common/collect/ImmutableEntry.java
index cc869b31aa21..edc25f490fd5 100644
--- a/android/guava/src/com/google/common/collect/ImmutableEntry.java
+++ b/android/guava/src/com/google/common/collect/ImmutableEntry.java
@@ -18,33 +18,36 @@
 
 import com.google.common.annotations.GwtCompatible;
 import java.io.Serializable;
-import org.checkerframework.checker.nullness.compatqual.NullableDecl;
+import org.checkerframework.checker.nullness.qual.Nullable;
 
 /** @see com.google.common.collect.Maps#immutableEntry(Object, Object) */
 @GwtCompatible(serializable = true)
-class ImmutableEntry<K, V> extends AbstractMapEntry<K, V> implements Serializable {
-  @NullableDecl final K key;
-  @NullableDecl final V value;
+@ElementTypesAreNonnullByDefault
+class ImmutableEntry<K extends @Nullable Object, V extends @Nullable Object>
+    extends AbstractMapEntry<K, V> implements Serializable {
+  @ParametricNullness final K key;
+  @ParametricNullness final V value;
 
-  ImmutableEntry(@NullableDecl K key, @NullableDecl V value) {
+  ImmutableEntry(@ParametricNullness K key, @ParametricNullness V value) {
     this.key = key;
     this.value = value;
   }
 
   @Override
-  @NullableDecl
+  @ParametricNullness
   public final K getKey() {
     return key;
   }
 
   @Override
-  @NullableDecl
+  @ParametricNullness
   public final V getValue() {
     return value;
   }
 
   @Override
-  public final V setValue(V value) {
+  @ParametricNullness
+  public final V setValue(@ParametricNullness V value) {
     throw new UnsupportedOperationException();
   }
 
diff --git a/android/guava/src/com/google/common/collect/ImmutableEnumMap.java b/android/guava/src/com/google/common/collect/ImmutableEnumMap.java
index beab47a9a0f7..66680f0e909e 100644
--- a/android/guava/src/com/google/common/collect/ImmutableEnumMap.java
+++ b/android/guava/src/com/google/common/collect/ImmutableEnumMap.java
@@ -22,7 +22,7 @@
 import com.google.common.collect.ImmutableMap.IteratorBasedImmutableMap;
 import java.io.Serializable;
 import java.util.EnumMap;
-import org.checkerframework.checker.nullness.compatqual.NullableDecl;
+import javax.annotation.CheckForNull;
 
 /**
  * Implementation of {@link ImmutableMap} backed by a non-empty {@link java.util.EnumMap}.
@@ -31,6 +31,7 @@
  */
 @GwtCompatible(serializable = true, emulated = true)
 @SuppressWarnings("serial") // we're overriding default serialization
+@ElementTypesAreNonnullByDefault
 final class ImmutableEnumMap<K extends Enum<K>, V> extends IteratorBasedImmutableMap<K, V> {
   static <K extends Enum<K>, V> ImmutableMap<K, V> asImmutable(EnumMap<K, V> map) {
     switch (map.size()) {
@@ -62,17 +63,18 @@ public int size() {
   }
 
   @Override
-  public boolean containsKey(@NullableDecl Object key) {
+  public boolean containsKey(@CheckForNull Object key) {
     return delegate.containsKey(key);
   }
 
   @Override
-  public V get(Object key) {
+  @CheckForNull
+  public V get(@CheckForNull Object key) {
     return delegate.get(key);
   }
 
   @Override
-  public boolean equals(Object object) {
+  public boolean equals(@CheckForNull Object object) {
     if (object == this) {
       return true;
     }
diff --git a/android/guava/src/com/google/common/collect/ImmutableEnumSet.java b/android/guava/src/com/google/common/collect/ImmutableEnumSet.java
index 4e189ffd0ade..90787e5d6349 100644
--- a/android/guava/src/com/google/common/collect/ImmutableEnumSet.java
+++ b/android/guava/src/com/google/common/collect/ImmutableEnumSet.java
@@ -21,6 +21,7 @@
 import java.io.Serializable;
 import java.util.Collection;
 import java.util.EnumSet;
+import javax.annotation.CheckForNull;
 
 /**
  * Implementation of {@link ImmutableSet} backed by a non-empty {@link java.util.EnumSet}.
@@ -29,6 +30,7 @@
  */
 @GwtCompatible(serializable = true, emulated = true)
 @SuppressWarnings("serial") // we're overriding default serialization
+@ElementTypesAreNonnullByDefault
 final class ImmutableEnumSet<E extends Enum<E>> extends ImmutableSet<E> {
   @SuppressWarnings("rawtypes") // necessary to compile against Java 8
   static ImmutableSet asImmutable(EnumSet set) {
@@ -72,7 +74,7 @@ public int size() {
   }
 
   @Override
-  public boolean contains(Object object) {
+  public boolean contains(@CheckForNull Object object) {
     return delegate.contains(object);
   }
 
@@ -90,7 +92,7 @@ public boolean isEmpty() {
   }
 
   @Override
-  public boolean equals(Object object) {
+  public boolean equals(@CheckForNull Object object) {
     if (object == this) {
       return true;
     }
diff --git a/android/guava/src/com/google/common/collect/ImmutableList.java b/android/guava/src/com/google/common/collect/ImmutableList.java
index c468336e769b..e336424f61e8 100644
--- a/android/guava/src/com/google/common/collect/ImmutableList.java
+++ b/android/guava/src/com/google/common/collect/ImmutableList.java
@@ -29,6 +29,7 @@
 import com.google.common.annotations.GwtCompatible;
 import com.google.errorprone.annotations.CanIgnoreReturnValue;
 import com.google.errorprone.annotations.DoNotCall;
+import com.google.errorprone.annotations.InlineMe;
 import java.io.InvalidObjectException;
 import java.io.ObjectInputStream;
 import java.io.Serializable;
@@ -39,14 +40,15 @@
 import java.util.Iterator;
 import java.util.List;
 import java.util.RandomAccess;
-import org.checkerframework.checker.nullness.compatqual.NullableDecl;
+import javax.annotation.CheckForNull;
+import org.checkerframework.checker.nullness.qual.Nullable;
 
 /**
  * A {@link List} whose contents will never change, with many other important properties detailed at
  * {@link ImmutableCollection}.
  *
  * <p>See the Guava User Guide article on <a href=
- * "https://github.com/google/guava/wiki/ImmutableCollectionsExplained"> immutable collections</a>.
+ * "https://github.com/google/guava/wiki/ImmutableCollectionsExplained">immutable collections</a>.
  *
  * @see ImmutableMap
  * @see ImmutableSet
@@ -55,12 +57,15 @@
  */
 @GwtCompatible(serializable = true, emulated = true)
 @SuppressWarnings("serial") // we're overriding default serialization
+@ElementTypesAreNonnullByDefault
 public abstract class ImmutableList<E> extends ImmutableCollection<E>
     implements List<E>, RandomAccess {
   /**
    * Returns the empty immutable list. This list behaves and performs comparably to {@link
    * Collections#emptyList}, and is preferable mainly for consistency and maintainability of your
    * code.
+   *
+   * <p><b>Performance note:</b> the instance returned is a singleton.
    */
   // Casting to any type is safe because the list will never hold any elements.
   @SuppressWarnings("unchecked")
@@ -337,7 +342,7 @@ static <E> ImmutableList<E> asImmutableList(Object[] elements) {
   }
 
   /** Views the array as an immutable list. Does not check for nulls. */
-  static <E> ImmutableList<E> asImmutableList(Object[] elements, int length) {
+  static <E> ImmutableList<E> asImmutableList(@Nullable Object[] elements, int length) {
     if (length == 0) {
       return of();
     }
@@ -388,17 +393,17 @@ protected E get(int index) {
   }
 
   @Override
-  public int indexOf(@NullableDecl Object object) {
+  public int indexOf(@CheckForNull Object object) {
     return (object == null) ? -1 : Lists.indexOfImpl(this, object);
   }
 
   @Override
-  public int lastIndexOf(@NullableDecl Object object) {
+  public int lastIndexOf(@CheckForNull Object object) {
     return (object == null) ? -1 : Lists.lastIndexOfImpl(this, object);
   }
 
   @Override
-  public boolean contains(@NullableDecl Object object) {
+  public boolean contains(@CheckForNull Object object) {
     return indexOf(object) >= 0;
   }
 
@@ -445,6 +450,8 @@ public int size() {
     }
 
     @Override
+    @CheckForNull
+    @Nullable
     Object[] internalArray() {
       return ImmutableList.this.internalArray();
     }
@@ -536,14 +543,17 @@ public final E remove(int index) {
    * Returns this list instance.
    *
    * @since 2.0
+   * @deprecated There is no reason to use this; it always returns {@code this}.
    */
+  @InlineMe(replacement = "this")
+  @Deprecated
   @Override
   public final ImmutableList<E> asList() {
     return this;
   }
 
   @Override
-  int copyIntoArray(Object[] dst, int offset) {
+  int copyIntoArray(@Nullable Object[] dst, int offset) {
     // this loop is faster for RandomAccess instances, which ImmutableLists are
     int size = size();
     for (int i = 0; i < size; i++) {
@@ -584,18 +594,18 @@ public ImmutableList<E> reverse() {
     }
 
     @Override
-    public boolean contains(@NullableDecl Object object) {
+    public boolean contains(@CheckForNull Object object) {
       return forwardList.contains(object);
     }
 
     @Override
-    public int indexOf(@NullableDecl Object object) {
+    public int indexOf(@CheckForNull Object object) {
       int index = forwardList.lastIndexOf(object);
       return (index >= 0) ? reverseIndex(index) : -1;
     }
 
     @Override
-    public int lastIndexOf(@NullableDecl Object object) {
+    public int lastIndexOf(@CheckForNull Object object) {
       int index = forwardList.indexOf(object);
       return (index >= 0) ? reverseIndex(index) : -1;
     }
@@ -624,7 +634,7 @@ boolean isPartialView() {
   }
 
   @Override
-  public boolean equals(@NullableDecl Object obj) {
+  public boolean equals(@CheckForNull Object obj) {
     return Lists.equalsImpl(this, obj);
   }
 
diff --git a/android/guava/src/com/google/common/collect/ImmutableListMultimap.java b/android/guava/src/com/google/common/collect/ImmutableListMultimap.java
index 027b252cd6d2..20408db80b1f 100644
--- a/android/guava/src/com/google/common/collect/ImmutableListMultimap.java
+++ b/android/guava/src/com/google/common/collect/ImmutableListMultimap.java
@@ -31,23 +31,29 @@
 import java.util.Comparator;
 import java.util.Map;
 import java.util.Map.Entry;
-import org.checkerframework.checker.nullness.compatqual.NullableDecl;
+import javax.annotation.CheckForNull;
+import org.checkerframework.checker.nullness.qual.Nullable;
 
 /**
  * A {@link ListMultimap} whose contents will never change, with many other important properties
  * detailed at {@link ImmutableCollection}.
  *
  * <p>See the Guava User Guide article on <a href=
- * "https://github.com/google/guava/wiki/ImmutableCollectionsExplained"> immutable collections</a>.
+ * "https://github.com/google/guava/wiki/ImmutableCollectionsExplained">immutable collections</a>.
  *
  * @author Jared Levy
  * @since 2.0
  */
 @GwtCompatible(serializable = true, emulated = true)
+@ElementTypesAreNonnullByDefault
 public class ImmutableListMultimap<K, V> extends ImmutableMultimap<K, V>
     implements ListMultimap<K, V> {
 
-  /** Returns the empty multimap. */
+  /**
+   * Returns the empty multimap.
+   *
+   * <p><b>Performance note:</b> the instance returned is a singleton.
+   */
   // Casting is safe because the multimap will never hold any elements.
   @SuppressWarnings("unchecked")
   public static <K, V> ImmutableListMultimap<K, V> of() {
@@ -274,7 +280,7 @@ public static <K, V> ImmutableListMultimap<K, V> copyOf(
   /** Creates an ImmutableListMultimap from an asMap.entrySet. */
   static <K, V> ImmutableListMultimap<K, V> fromMapEntries(
       Collection<? extends Map.Entry<? extends K, ? extends Collection<? extends V>>> mapEntries,
-      @NullableDecl Comparator<? super V> valueComparator) {
+      @Nullable Comparator<? super V> valueComparator) {
     if (mapEntries.isEmpty()) {
       return of();
     }
@@ -295,7 +301,7 @@ static <K, V> ImmutableListMultimap<K, V> fromMapEntries(
       }
     }
 
-    return new ImmutableListMultimap<>(builder.build(), size);
+    return new ImmutableListMultimap<>(builder.buildOrThrow(), size);
   }
 
   ImmutableListMultimap(ImmutableMap<K, ImmutableList<V>> map, int size) {
@@ -310,13 +316,13 @@ static <K, V> ImmutableListMultimap<K, V> fromMapEntries(
    * parameters used to build this multimap.
    */
   @Override
-  public ImmutableList<V> get(@NullableDecl K key) {
+  public ImmutableList<V> get(K key) {
     // This cast is safe as its type is known in constructor.
     ImmutableList<V> list = (ImmutableList<V>) map.get(key);
     return (list == null) ? ImmutableList.<V>of() : list;
   }
 
-  @LazyInit @RetainedWith private transient ImmutableListMultimap<V, K> inverse;
+  @LazyInit @RetainedWith @CheckForNull private transient ImmutableListMultimap<V, K> inverse;
 
   /**
    * {@inheritDoc}
@@ -353,7 +359,7 @@ private ImmutableListMultimap<V, K> invert() {
   @Deprecated
   @Override
   @DoNotCall("Always throws UnsupportedOperationException")
-  public final ImmutableList<V> removeAll(Object key) {
+  public final ImmutableList<V> removeAll(@CheckForNull Object key) {
     throw new UnsupportedOperationException();
   }
 
@@ -408,7 +414,7 @@ private void readObject(ObjectInputStream stream) throws IOException, ClassNotFo
 
     ImmutableMap<Object, ImmutableList<Object>> tmpMap;
     try {
-      tmpMap = builder.build();
+      tmpMap = builder.buildOrThrow();
     } catch (IllegalArgumentException e) {
       throw (InvalidObjectException) new InvalidObjectException(e.getMessage()).initCause(e);
     }
diff --git a/android/guava/src/com/google/common/collect/ImmutableMap.java b/android/guava/src/com/google/common/collect/ImmutableMap.java
index 958fa2efc632..1746ae0b41f3 100644
--- a/android/guava/src/com/google/common/collect/ImmutableMap.java
+++ b/android/guava/src/com/google/common/collect/ImmutableMap.java
@@ -20,6 +20,7 @@
 import static com.google.common.base.Preconditions.checkState;
 import static com.google.common.collect.CollectPreconditions.checkEntryNotNull;
 import static com.google.common.collect.CollectPreconditions.checkNonnegative;
+import static java.util.Objects.requireNonNull;
 
 import com.google.common.annotations.Beta;
 import com.google.common.annotations.GwtCompatible;
@@ -32,21 +33,25 @@
 import java.io.Serializable;
 import java.util.AbstractMap;
 import java.util.Arrays;
+import java.util.BitSet;
 import java.util.Collection;
 import java.util.Collections;
 import java.util.Comparator;
+import java.util.HashSet;
 import java.util.Iterator;
 import java.util.Map;
 import java.util.Map.Entry;
+import java.util.Set;
 import java.util.SortedMap;
-import org.checkerframework.checker.nullness.compatqual.NullableDecl;
+import javax.annotation.CheckForNull;
+import org.checkerframework.checker.nullness.qual.Nullable;
 
 /**
  * A {@link Map} whose contents will never change, with many other important properties detailed at
  * {@link ImmutableCollection}.
  *
  * <p>See the Guava User Guide article on <a href=
- * "https://github.com/google/guava/wiki/ImmutableCollectionsExplained"> immutable collections</a>.
+ * "https://github.com/google/guava/wiki/ImmutableCollectionsExplained">immutable collections</a>.
  *
  * @author Jesse Wilson
  * @author Kevin Bourrillion
@@ -55,12 +60,15 @@
 @DoNotMock("Use ImmutableMap.of or another implementation")
 @GwtCompatible(serializable = true, emulated = true)
 @SuppressWarnings("serial") // we're overriding default serialization
+@ElementTypesAreNonnullByDefault
 public abstract class ImmutableMap<K, V> implements Map<K, V>, Serializable {
 
   /**
    * Returns the empty map. This map behaves and performs comparably to {@link
    * Collections#emptyMap}, and is preferable mainly for consistency and maintainability of your
    * code.
+   *
+   * <p><b>Performance note:</b> the instance returned is a singleton.
    */
   @SuppressWarnings("unchecked")
   public static <K, V> ImmutableMap<K, V> of() {
@@ -128,7 +136,170 @@ public static <K, V> ImmutableMap<K, V> of(
     return RegularImmutableMap.create(5, new Object[] {k1, v1, k2, v2, k3, v3, k4, v4, k5, v5});
   }
 
-  // looking for of() with > 5 entries? Use the builder instead.
+  /**
+   * Returns an immutable map containing the given entries, in order.
+   *
+   * @throws IllegalArgumentException if duplicate keys are provided
+   * @since 31.0
+   */
+  public static <K, V> ImmutableMap<K, V> of(
+      K k1, V v1, K k2, V v2, K k3, V v3, K k4, V v4, K k5, V v5, K k6, V v6) {
+    checkEntryNotNull(k1, v1);
+    checkEntryNotNull(k2, v2);
+    checkEntryNotNull(k3, v3);
+    checkEntryNotNull(k4, v4);
+    checkEntryNotNull(k5, v5);
+    checkEntryNotNull(k6, v6);
+    return RegularImmutableMap.create(
+        6, new Object[] {k1, v1, k2, v2, k3, v3, k4, v4, k5, v5, k6, v6});
+  }
+  /**
+   * Returns an immutable map containing the given entries, in order.
+   *
+   * @throws IllegalArgumentException if duplicate keys are provided
+   * @since 31.0
+   */
+  public static <K, V> ImmutableMap<K, V> of(
+      K k1, V v1, K k2, V v2, K k3, V v3, K k4, V v4, K k5, V v5, K k6, V v6, K k7, V v7) {
+    checkEntryNotNull(k1, v1);
+    checkEntryNotNull(k2, v2);
+    checkEntryNotNull(k3, v3);
+    checkEntryNotNull(k4, v4);
+    checkEntryNotNull(k5, v5);
+    checkEntryNotNull(k6, v6);
+    checkEntryNotNull(k7, v7);
+    return RegularImmutableMap.create(
+        7, new Object[] {k1, v1, k2, v2, k3, v3, k4, v4, k5, v5, k6, v6, k7, v7});
+  }
+  /**
+   * Returns an immutable map containing the given entries, in order.
+   *
+   * @throws IllegalArgumentException if duplicate keys are provided
+   * @since 31.0
+   */
+  public static <K, V> ImmutableMap<K, V> of(
+      K k1,
+      V v1,
+      K k2,
+      V v2,
+      K k3,
+      V v3,
+      K k4,
+      V v4,
+      K k5,
+      V v5,
+      K k6,
+      V v6,
+      K k7,
+      V v7,
+      K k8,
+      V v8) {
+    checkEntryNotNull(k1, v1);
+    checkEntryNotNull(k2, v2);
+    checkEntryNotNull(k3, v3);
+    checkEntryNotNull(k4, v4);
+    checkEntryNotNull(k5, v5);
+    checkEntryNotNull(k6, v6);
+    checkEntryNotNull(k7, v7);
+    checkEntryNotNull(k8, v8);
+    return RegularImmutableMap.create(
+        8, new Object[] {k1, v1, k2, v2, k3, v3, k4, v4, k5, v5, k6, v6, k7, v7, k8, v8});
+  }
+  /**
+   * Returns an immutable map containing the given entries, in order.
+   *
+   * @throws IllegalArgumentException if duplicate keys are provided
+   * @since 31.0
+   */
+  public static <K, V> ImmutableMap<K, V> of(
+      K k1,
+      V v1,
+      K k2,
+      V v2,
+      K k3,
+      V v3,
+      K k4,
+      V v4,
+      K k5,
+      V v5,
+      K k6,
+      V v6,
+      K k7,
+      V v7,
+      K k8,
+      V v8,
+      K k9,
+      V v9) {
+    checkEntryNotNull(k1, v1);
+    checkEntryNotNull(k2, v2);
+    checkEntryNotNull(k3, v3);
+    checkEntryNotNull(k4, v4);
+    checkEntryNotNull(k5, v5);
+    checkEntryNotNull(k6, v6);
+    checkEntryNotNull(k7, v7);
+    checkEntryNotNull(k8, v8);
+    checkEntryNotNull(k9, v9);
+    return RegularImmutableMap.create(
+        9, new Object[] {k1, v1, k2, v2, k3, v3, k4, v4, k5, v5, k6, v6, k7, v7, k8, v8, k9, v9});
+  }
+  /**
+   * Returns an immutable map containing the given entries, in order.
+   *
+   * @throws IllegalArgumentException if duplicate keys are provided
+   * @since 31.0
+   */
+  public static <K, V> ImmutableMap<K, V> of(
+      K k1,
+      V v1,
+      K k2,
+      V v2,
+      K k3,
+      V v3,
+      K k4,
+      V v4,
+      K k5,
+      V v5,
+      K k6,
+      V v6,
+      K k7,
+      V v7,
+      K k8,
+      V v8,
+      K k9,
+      V v9,
+      K k10,
+      V v10) {
+    checkEntryNotNull(k1, v1);
+    checkEntryNotNull(k2, v2);
+    checkEntryNotNull(k3, v3);
+    checkEntryNotNull(k4, v4);
+    checkEntryNotNull(k5, v5);
+    checkEntryNotNull(k6, v6);
+    checkEntryNotNull(k7, v7);
+    checkEntryNotNull(k8, v8);
+    checkEntryNotNull(k9, v9);
+    checkEntryNotNull(k10, v10);
+    return RegularImmutableMap.create(
+        10,
+        new Object[] {
+          k1, v1, k2, v2, k3, v3, k4, v4, k5, v5, k6, v6, k7, v7, k8, v8, k9, v9, k10, v10
+        });
+  }
+
+  // looking for of() with > 10 entries? Use the builder or ofEntries instead.
+
+  /**
+   * Returns an immutable map containing the given entries, in order.
+   *
+   * @throws IllegalArgumentException if duplicate keys are provided
+   * @since 31.0
+   */
+  @SafeVarargs
+  public static <K, V> ImmutableMap<K, V> ofEntries(Entry<? extends K, ? extends V>... entries) {
+    @SuppressWarnings("unchecked") // we will only ever read these
+    Entry<K, V>[] entries2 = (Entry<K, V>[]) entries;
+    return copyOf(Arrays.asList(entries2));
+  }
 
   /**
    * Verifies that {@code key} and {@code value} are non-null, and returns a new immutable entry
@@ -169,7 +340,7 @@ public static <K, V> Builder<K, V> builderWithExpectedSize(int expectedSize) {
   }
 
   static void checkNoConflict(
-      boolean safe, String conflictDescription, Entry<?, ?> entry1, Entry<?, ?> entry2) {
+      boolean safe, String conflictDescription, Object entry1, Object entry2) {
     if (!safe) {
       throw conflictException(conflictDescription, entry1, entry2);
     }
@@ -191,7 +362,7 @@ static IllegalArgumentException conflictException(
    *         .put("one", 1)
    *         .put("two", 2)
    *         .put("three", 3)
-   *         .build();
+   *         .buildOrThrow();
    * }</pre>
    *
    * <p>For <i>small</i> immutable maps, the {@code ImmutableMap.of()} methods are even more
@@ -205,17 +376,22 @@ static IllegalArgumentException conflictException(
    * sort by keys, or call {@link #orderEntriesByValue(Comparator)}, which changes this builder to
    * sort entries by value.
    *
-   * <p>Builder instances can be reused - it is safe to call {@link #build} multiple times to build
-   * multiple maps in series. Each map is a superset of the maps created before it.
+   * <p>Builder instances can be reused - it is safe to call {@link #buildOrThrow} multiple times to
+   * build multiple maps in series. Each map is a superset of the maps created before it.
    *
    * @since 2.0
    */
   @DoNotMock
   public static class Builder<K, V> {
-    @NullableDecl Comparator<? super V> valueComparator;
-    Object[] alternatingKeysAndValues;
+    @CheckForNull Comparator<? super V> valueComparator;
+    @Nullable Object[] alternatingKeysAndValues;
     int size;
     boolean entriesUsed;
+    /**
+     * If non-null, a duplicate key we found in a previous buildKeepingLast() or buildOrThrow()
+     * call. A later buildOrThrow() can simply report this duplicate immediately.
+     */
+    @Nullable DuplicateKey duplicateKey;
 
     /**
      * Creates a new builder. The returned builder is equivalent to the builder generated by {@link
@@ -225,9 +401,9 @@ public Builder() {
       this(ImmutableCollection.Builder.DEFAULT_INITIAL_CAPACITY);
     }
 
-    @SuppressWarnings("unchecked")
+    @SuppressWarnings({"unchecked", "rawtypes"})
     Builder(int initialCapacity) {
-      this.alternatingKeysAndValues = new Object[2 * initialCapacity];
+      this.alternatingKeysAndValues = new @Nullable Object[2 * initialCapacity];
       this.size = 0;
       this.entriesUsed = false;
     }
@@ -244,8 +420,9 @@ private void ensureCapacity(int minCapacity) {
     }
 
     /**
-     * Associates {@code key} with {@code value} in the built map. Duplicate keys are not allowed,
-     * and will cause {@link #build} to fail.
+     * Associates {@code key} with {@code value} in the built map. If the same key is put more than
+     * once, {@link #buildOrThrow} will fail, while {@link #buildKeepingLast} will keep the last
+     * value put for that key.
      */
     @CanIgnoreReturnValue
     public Builder<K, V> put(K key, V value) {
@@ -258,8 +435,9 @@ public Builder<K, V> put(K key, V value) {
     }
 
     /**
-     * Adds the given {@code entry} to the map, making it immutable if necessary. Duplicate keys are
-     * not allowed, and will cause {@link #build} to fail.
+     * Adds the given {@code entry} to the map, making it immutable if necessary. If the same key is
+     * put more than once, {@link #buildOrThrow} will fail, while {@link #buildKeepingLast} will
+     * keep the last value put for that key.
      *
      * @since 11.0
      */
@@ -269,8 +447,9 @@ public Builder<K, V> put(Entry<? extends K, ? extends V> entry) {
     }
 
     /**
-     * Associates all of the given map's keys and values in the built map. Duplicate keys are not
-     * allowed, and will cause {@link #build} to fail.
+     * Associates all of the given map's keys and values in the built map. If the same key is put
+     * more than once, {@link #buildOrThrow} will fail, while {@link #buildKeepingLast} will keep
+     * the last value put for that key.
      *
      * @throws NullPointerException if any key or value in {@code map} is null
      */
@@ -280,8 +459,9 @@ public Builder<K, V> putAll(Map<? extends K, ? extends V> map) {
     }
 
     /**
-     * Adds all of the given entries to the built map. Duplicate keys are not allowed, and will
-     * cause {@link #build} to fail.
+     * Adds all of the given entries to the built map. If the same key is put more than once, {@link
+     * #buildOrThrow} will fail, while {@link #buildKeepingLast} will keep the last value put for
+     * that key.
      *
      * @throws NullPointerException if any key, value, or entry is null
      * @since 19.0
@@ -330,50 +510,157 @@ Builder<K, V> combine(Builder<K, V> other) {
       return this;
     }
 
-    /*
-     * TODO(kevinb): Should build() and the ImmutableBiMap & ImmutableSortedMap
-     * versions throw an IllegalStateException instead?
-     */
+    private ImmutableMap<K, V> build(boolean throwIfDuplicateKeys) {
+      if (throwIfDuplicateKeys && duplicateKey != null) {
+        throw duplicateKey.exception();
+      }
+      /*
+       * If entries is full, then this implementation may end up using the entries array
+       * directly and writing over the entry objects with non-terminal entries, but this is
+       * safe; if this Builder is used further, it will grow the entries array (so it can't
+       * affect the original array), and future build() calls will always copy any entry
+       * objects that cannot be safely reused.
+       */
+      // localAlternatingKeysAndValues is an alias for the alternatingKeysAndValues field, except if
+      // we end up removing duplicates in a copy of the array.
+      @Nullable Object[] localAlternatingKeysAndValues;
+      int localSize = size;
+      if (valueComparator == null) {
+        localAlternatingKeysAndValues = alternatingKeysAndValues;
+      } else {
+        if (entriesUsed) {
+          alternatingKeysAndValues = Arrays.copyOf(alternatingKeysAndValues, 2 * size);
+        }
+        localAlternatingKeysAndValues = alternatingKeysAndValues;
+        if (!throwIfDuplicateKeys) {
+          // We want to retain only the last-put value for any given key, before sorting.
+          // This could be improved, but orderEntriesByValue is rather rarely used anyway.
+          localAlternatingKeysAndValues = lastEntryForEachKey(localAlternatingKeysAndValues, size);
+          if (localAlternatingKeysAndValues.length < alternatingKeysAndValues.length) {
+            localSize = localAlternatingKeysAndValues.length >>> 1;
+          }
+        }
+        sortEntries(localAlternatingKeysAndValues, localSize, valueComparator);
+      }
+      entriesUsed = true;
+      ImmutableMap<K, V> map =
+          RegularImmutableMap.create(localSize, localAlternatingKeysAndValues, this);
+      if (throwIfDuplicateKeys && duplicateKey != null) {
+        throw duplicateKey.exception();
+      }
+      return map;
+    }
 
     /**
      * Returns a newly-created immutable map. The iteration order of the returned map is the order
      * in which entries were inserted into the builder, unless {@link #orderEntriesByValue} was
      * called, in which case entries are sorted by value.
      *
+     * <p>Prefer the equivalent method {@link #buildOrThrow()} to make it explicit that the method
+     * will throw an exception if there are duplicate keys. The {@code build()} method will soon be
+     * deprecated.
+     *
      * @throws IllegalArgumentException if duplicate keys were added
      */
-    @SuppressWarnings("unchecked")
     public ImmutableMap<K, V> build() {
-      /*
-       * If entries is full, then this implementation may end up using the entries array
-       * directly and writing over the entry objects with non-terminal entries, but this is
-       * safe; if this Builder is used further, it will grow the entries array (so it can't
-       * affect the original array), and future build() calls will always copy any entry
-       * objects that cannot be safely reused.
-       */
-      sortEntries();
-      entriesUsed = true;
-      return RegularImmutableMap.create(size, alternatingKeysAndValues);
+      return buildOrThrow();
     }
 
-    void sortEntries() {
-      if (valueComparator != null) {
-        if (entriesUsed) {
-          alternatingKeysAndValues = Arrays.copyOf(alternatingKeysAndValues, 2 * size);
-        }
-        Entry<K, V>[] entries = new Entry[size];
-        for (int i = 0; i < size; i++) {
-          entries[i] =
-              new AbstractMap.SimpleImmutableEntry<K, V>(
-                  (K) alternatingKeysAndValues[2 * i], (V) alternatingKeysAndValues[2 * i + 1]);
+    /**
+     * Returns a newly-created immutable map, or throws an exception if any key was added more than
+     * once. The iteration order of the returned map is the order in which entries were inserted
+     * into the builder, unless {@link #orderEntriesByValue} was called, in which case entries are
+     * sorted by value.
+     *
+     * @throws IllegalArgumentException if duplicate keys were added
+     * @since 31.0
+     */
+    public ImmutableMap<K, V> buildOrThrow() {
+      return build(true);
+    }
+
+    /**
+     * Returns a newly-created immutable map, using the last value for any key that was added more
+     * than once. The iteration order of the returned map is the order in which entries were
+     * inserted into the builder, unless {@link #orderEntriesByValue} was called, in which case
+     * entries are sorted by value. If a key was added more than once, it appears in iteration order
+     * based on the first time it was added, again unless {@link #orderEntriesByValue} was called.
+     *
+     * <p>In the current implementation, all values associated with a given key are stored in the
+     * {@code Builder} object, even though only one of them will be used in the built map. If there
+     * can be many repeated keys, it may be more space-efficient to use a {@link
+     * java.util.LinkedHashMap LinkedHashMap} and {@link ImmutableMap#copyOf(Map)} rather than
+     * {@code ImmutableMap.Builder}.
+     *
+     * @since 31.1
+     */
+    public ImmutableMap<K, V> buildKeepingLast() {
+      return build(false);
+    }
+
+    static <V> void sortEntries(
+        @Nullable Object[] alternatingKeysAndValues,
+        int size,
+        Comparator<? super V> valueComparator) {
+      @SuppressWarnings({"rawtypes", "unchecked"})
+      Entry<Object, V>[] entries = new Entry[size];
+      for (int i = 0; i < size; i++) {
+        // requireNonNull is safe because the first `2*size` elements have been filled in.
+        Object key = requireNonNull(alternatingKeysAndValues[2 * i]);
+        @SuppressWarnings("unchecked")
+        V value = (V) requireNonNull(alternatingKeysAndValues[2 * i + 1]);
+        entries[i] = new AbstractMap.SimpleImmutableEntry<Object, V>(key, value);
+      }
+      Arrays.sort(
+          entries, 0, size, Ordering.from(valueComparator).onResultOf(Maps.<V>valueFunction()));
+      for (int i = 0; i < size; i++) {
+        alternatingKeysAndValues[2 * i] = entries[i].getKey();
+        alternatingKeysAndValues[2 * i + 1] = entries[i].getValue();
+      }
+    }
+
+    private @Nullable Object[] lastEntryForEachKey(
+        @Nullable Object[] localAlternatingKeysAndValues, int size) {
+      Set<Object> seenKeys = new HashSet<>();
+      BitSet dups = new BitSet(); // slots that are overridden by a later duplicate key
+      for (int i = size - 1; i >= 0; i--) {
+        Object key = requireNonNull(localAlternatingKeysAndValues[2 * i]);
+        if (!seenKeys.add(key)) {
+          dups.set(i);
         }
-        Arrays.sort(
-            entries, 0, size, Ordering.from(valueComparator).onResultOf(Maps.<V>valueFunction()));
-        for (int i = 0; i < size; i++) {
-          alternatingKeysAndValues[2 * i] = entries[i].getKey();
-          alternatingKeysAndValues[2 * i + 1] = entries[i].getValue();
+      }
+      if (dups.isEmpty()) {
+        return localAlternatingKeysAndValues;
+      }
+      Object[] newAlternatingKeysAndValues = new Object[(size - dups.cardinality()) * 2];
+      for (int inI = 0, outI = 0; inI < size * 2; ) {
+        if (dups.get(inI >>> 1)) {
+          inI += 2;
+        } else {
+          newAlternatingKeysAndValues[outI++] =
+              requireNonNull(localAlternatingKeysAndValues[inI++]);
+          newAlternatingKeysAndValues[outI++] =
+              requireNonNull(localAlternatingKeysAndValues[inI++]);
         }
       }
+      return newAlternatingKeysAndValues;
+    }
+
+    static final class DuplicateKey {
+      private final Object key;
+      private final Object value1;
+      private final Object value2;
+
+      DuplicateKey(Object key, Object value1, Object value2) {
+        this.key = key;
+        this.value1 = value1;
+        this.value2 = value2;
+      }
+
+      IllegalArgumentException exception() {
+        return new IllegalArgumentException(
+            "Multiple entries with same key: " + key + "=" + value1 + " and " + key + "=" + value2);
+      }
     }
   }
 
@@ -464,6 +751,7 @@ ImmutableCollection<V> createValues() {
   @Deprecated
   @Override
   @DoNotCall("Always throws UnsupportedOperationException")
+  @CheckForNull
   public final V put(K k, V v) {
     throw new UnsupportedOperationException();
   }
@@ -477,7 +765,8 @@ public final V put(K k, V v) {
   @CanIgnoreReturnValue
   @Deprecated
   @Override
-  public final V remove(Object o) {
+  @CheckForNull
+  public final V remove(@CheckForNull Object o) {
     throw new UnsupportedOperationException();
   }
 
@@ -513,18 +802,19 @@ public boolean isEmpty() {
   }
 
   @Override
-  public boolean containsKey(@NullableDecl Object key) {
+  public boolean containsKey(@CheckForNull Object key) {
     return get(key) != null;
   }
 
   @Override
-  public boolean containsValue(@NullableDecl Object value) {
+  public boolean containsValue(@CheckForNull Object value) {
     return values().contains(value);
   }
 
   // Overriding to mark it Nullable
   @Override
-  public abstract V get(@NullableDecl Object key);
+  @CheckForNull
+  public abstract V get(@CheckForNull Object key);
 
   /**
    * {@inheritDoc}
@@ -538,12 +828,43 @@ public boolean containsValue(@NullableDecl Object value) {
    *     Note that API Level 24 users can call this method with any version of Guava.
    */
   // @Override under Java 8 / API Level 24
-  public final V getOrDefault(@NullableDecl Object key, @NullableDecl V defaultValue) {
+  @CheckForNull
+  public final V getOrDefault(@CheckForNull Object key, @CheckForNull V defaultValue) {
+    /*
+     * Even though it's weird to pass a defaultValue that is null, some callers do so. Those who
+     * pass a literal "null" should probably just use `get`, but I would expect other callers to
+     * pass an expression that *might* be null. This could happen with:
+     *
+     * - a `getFooOrDefault(@CheckForNull Foo defaultValue)` method that returns
+     *   `map.getOrDefault(FOO_KEY, defaultValue)`
+     *
+     * - a call that consults a chain of maps, as in `mapA.getOrDefault(key, mapB.getOrDefault(key,
+     *   ...))`
+     *
+     * So it makes sense for the parameter (and thus the return type) to be @CheckForNull.
+     *
+     * Two other points:
+     *
+     * 1. We'll want to use something like @PolyNull once we can make that work for the various
+     * platforms we target.
+     *
+     * 2. Kotlin's Map type has a getOrDefault method that accepts and returns a "plain V," in
+     * contrast to the "V?" type that we're using. As a result, Kotlin sees a conflict between the
+     * nullness annotations in ImmutableMap and those in its own Map type. In response, it considers
+     * the parameter and return type both to be platform types. As a result, Kotlin permits calls
+     * that can lead to NullPointerException. That's unfortunate. But hopefully most Kotlin callers
+     * use `get(key) ?: defaultValue` instead of this method, anyway.
+     */
     V result = get(key);
-    return (result != null) ? result : defaultValue;
+    // TODO(b/192579700): Use a ternary once it no longer confuses our nullness checker.
+    if (result != null) {
+      return result;
+    } else {
+      return defaultValue;
+    }
   }
 
-  @LazyInit @RetainedWith private transient ImmutableSet<Entry<K, V>> entrySet;
+  @LazyInit @RetainedWith @CheckForNull private transient ImmutableSet<Entry<K, V>> entrySet;
 
   /**
    * Returns an immutable set of the mappings in this map. The iteration order is specified by the
@@ -557,7 +878,7 @@ public ImmutableSet<Entry<K, V>> entrySet() {
 
   abstract ImmutableSet<Entry<K, V>> createEntrySet();
 
-  @LazyInit @RetainedWith private transient ImmutableSet<K> keySet;
+  @LazyInit @RetainedWith @CheckForNull private transient ImmutableSet<K> keySet;
 
   /**
    * Returns an immutable set of the keys in this map, in the same order that they appear in {@link
@@ -591,7 +912,7 @@ public K next() {
     };
   }
 
-  @LazyInit @RetainedWith private transient ImmutableCollection<V> values;
+  @LazyInit @RetainedWith @CheckForNull private transient ImmutableCollection<V> values;
 
   /**
    * Returns an immutable collection of the values in this map, in the same order that they appear
@@ -611,7 +932,7 @@ public ImmutableCollection<V> values() {
   abstract ImmutableCollection<V> createValues();
 
   // cached so that this.multimapView().inverse() only computes inverse once
-  @LazyInit private transient ImmutableSetMultimap<K, V> multimapView;
+  @LazyInit @CheckForNull private transient ImmutableSetMultimap<K, V> multimapView;
 
   /**
    * Returns a multimap view of the map.
@@ -644,12 +965,13 @@ ImmutableSet<K> createKeySet() {
     }
 
     @Override
-    public boolean containsKey(@NullableDecl Object key) {
+    public boolean containsKey(@CheckForNull Object key) {
       return ImmutableMap.this.containsKey(key);
     }
 
     @Override
-    public ImmutableSet<V> get(@NullableDecl Object key) {
+    @CheckForNull
+    public ImmutableSet<V> get(@CheckForNull Object key) {
       V outerValue = ImmutableMap.this.get(key);
       return (outerValue == null) ? null : ImmutableSet.of(outerValue);
     }
@@ -699,7 +1021,7 @@ public ImmutableSet<V> getValue() {
   }
 
   @Override
-  public boolean equals(@NullableDecl Object object) {
+  public boolean equals(@CheckForNull Object object) {
     return Maps.equalsImpl(this, object);
   }
 
@@ -740,7 +1062,8 @@ static class SerializedForm<K, V> implements Serializable {
         Object[] keys = new Object[map.size()];
         Object[] values = new Object[map.size()];
         int i = 0;
-        for (Entry<?, ?> entry : map.entrySet()) {
+        // "extends Object" works around https://github.com/typetools/checker-framework/issues/3013
+        for (Entry<? extends Object, ? extends Object> entry : map.entrySet()) {
           keys[i] = entry.getKey();
           values[i] = entry.getValue();
           i++;
@@ -771,7 +1094,7 @@ final Object readResolve() {
         builder.put(keyIter.next(), valueIter.next());
       }
 
-      return builder.build();
+      return builder.buildOrThrow();
     }
 
     @SuppressWarnings("unchecked")
@@ -784,7 +1107,7 @@ final Object legacyReadResolve() {
       for (int i = 0; i < keys.length; i++) {
         builder.put(keys[i], values[i]);
       }
-      return builder.build();
+      return builder.buildOrThrow();
     }
 
     /**
diff --git a/android/guava/src/com/google/common/collect/ImmutableMapEntrySet.java b/android/guava/src/com/google/common/collect/ImmutableMapEntrySet.java
index 72fc5cf3c91d..7ae6422e2dfb 100644
--- a/android/guava/src/com/google/common/collect/ImmutableMapEntrySet.java
+++ b/android/guava/src/com/google/common/collect/ImmutableMapEntrySet.java
@@ -20,7 +20,8 @@
 import com.google.common.annotations.GwtIncompatible;
 import java.io.Serializable;
 import java.util.Map.Entry;
-import org.checkerframework.checker.nullness.compatqual.NullableDecl;
+import javax.annotation.CheckForNull;
+import org.checkerframework.checker.nullness.qual.Nullable;
 
 /**
  * {@code entrySet()} implementation for {@link ImmutableMap}.
@@ -29,6 +30,7 @@
  * @author Kevin Bourrillion
  */
 @GwtCompatible(emulated = true)
+@ElementTypesAreNonnullByDefault
 abstract class ImmutableMapEntrySet<K, V> extends ImmutableSet<Entry<K, V>> {
   static final class RegularEntrySet<K, V> extends ImmutableMapEntrySet<K, V> {
     private final transient ImmutableMap<K, V> map;
@@ -50,7 +52,7 @@ ImmutableMap<K, V> map() {
 
     @Override
     @GwtIncompatible("not used in GWT")
-    int copyIntoArray(Object[] dst, int offset) {
+    int copyIntoArray(@Nullable Object[] dst, int offset) {
       return entries.copyIntoArray(dst, offset);
     }
 
@@ -75,7 +77,7 @@ public int size() {
   }
 
   @Override
-  public boolean contains(@NullableDecl Object object) {
+  public boolean contains(@CheckForNull Object object) {
     if (object instanceof Entry) {
       Entry<?, ?> entry = (Entry<?, ?>) object;
       V value = map().get(entry.getKey());
diff --git a/android/guava/src/com/google/common/collect/ImmutableMapKeySet.java b/android/guava/src/com/google/common/collect/ImmutableMapKeySet.java
index 77babc276e5d..9bd1d43386b8 100644
--- a/android/guava/src/com/google/common/collect/ImmutableMapKeySet.java
+++ b/android/guava/src/com/google/common/collect/ImmutableMapKeySet.java
@@ -19,7 +19,7 @@
 import com.google.common.annotations.GwtCompatible;
 import com.google.common.annotations.GwtIncompatible;
 import java.io.Serializable;
-import org.checkerframework.checker.nullness.compatqual.NullableDecl;
+import javax.annotation.CheckForNull;
 
 /**
  * {@code keySet()} implementation for {@link ImmutableMap}.
@@ -28,6 +28,7 @@
  * @author Kevin Bourrillion
  */
 @GwtCompatible(emulated = true)
+@ElementTypesAreNonnullByDefault
 final class ImmutableMapKeySet<K, V> extends IndexedImmutableSet<K> {
   private final ImmutableMap<K, V> map;
 
@@ -46,7 +47,7 @@ public UnmodifiableIterator<K> iterator() {
   }
 
   @Override
-  public boolean contains(@NullableDecl Object object) {
+  public boolean contains(@CheckForNull Object object) {
     return map.containsKey(object);
   }
 
diff --git a/android/guava/src/com/google/common/collect/ImmutableMapValues.java b/android/guava/src/com/google/common/collect/ImmutableMapValues.java
index 4a0e3960d581..8b7284d1e33c 100644
--- a/android/guava/src/com/google/common/collect/ImmutableMapValues.java
+++ b/android/guava/src/com/google/common/collect/ImmutableMapValues.java
@@ -20,7 +20,7 @@
 import com.google.common.annotations.GwtIncompatible;
 import java.io.Serializable;
 import java.util.Map.Entry;
-import org.checkerframework.checker.nullness.compatqual.NullableDecl;
+import javax.annotation.CheckForNull;
 
 /**
  * {@code values()} implementation for {@link ImmutableMap}.
@@ -29,6 +29,7 @@
  * @author Kevin Bourrillion
  */
 @GwtCompatible(emulated = true)
+@ElementTypesAreNonnullByDefault
 final class ImmutableMapValues<K, V> extends ImmutableCollection<V> {
   private final ImmutableMap<K, V> map;
 
@@ -59,7 +60,7 @@ public V next() {
   }
 
   @Override
-  public boolean contains(@NullableDecl Object object) {
+  public boolean contains(@CheckForNull Object object) {
     return object != null && Iterators.contains(iterator(), object);
   }
 
diff --git a/android/guava/src/com/google/common/collect/ImmutableMultimap.java b/android/guava/src/com/google/common/collect/ImmutableMultimap.java
index 9234b1cf1679..fa1f3a4c2ff4 100644
--- a/android/guava/src/com/google/common/collect/ImmutableMultimap.java
+++ b/android/guava/src/com/google/common/collect/ImmutableMultimap.java
@@ -18,11 +18,14 @@
 
 import static com.google.common.base.Preconditions.checkNotNull;
 import static com.google.common.collect.CollectPreconditions.checkEntryNotNull;
+import static com.google.common.collect.Maps.immutableEntry;
+import static java.util.Objects.requireNonNull;
 
 import com.google.common.annotations.Beta;
 import com.google.common.annotations.GwtCompatible;
 import com.google.common.annotations.GwtIncompatible;
 import com.google.errorprone.annotations.CanIgnoreReturnValue;
+import com.google.errorprone.annotations.DoNotCall;
 import com.google.errorprone.annotations.DoNotMock;
 import com.google.j2objc.annotations.Weak;
 import com.google.j2objc.annotations.WeakOuter;
@@ -35,7 +38,8 @@
 import java.util.Map;
 import java.util.Map.Entry;
 import java.util.Set;
-import org.checkerframework.checker.nullness.compatqual.NullableDecl;
+import javax.annotation.CheckForNull;
+import org.checkerframework.checker.nullness.qual.Nullable;
 
 /**
  * A {@link Multimap} whose contents will never change, with many other important properties
@@ -58,16 +62,21 @@
  * immediately after the last entry having that key.
  *
  * <p>See the Guava User Guide article on <a href=
- * "https://github.com/google/guava/wiki/ImmutableCollectionsExplained"> immutable collections</a>.
+ * "https://github.com/google/guava/wiki/ImmutableCollectionsExplained">immutable collections</a>.
  *
  * @author Jared Levy
  * @since 2.0
  */
 @GwtCompatible(emulated = true)
+@ElementTypesAreNonnullByDefault
 public abstract class ImmutableMultimap<K, V> extends BaseImmutableMultimap<K, V>
     implements Serializable {
 
-  /** Returns an empty multimap. */
+  /**
+   * Returns an empty multimap.
+   *
+   * <p><b>Performance note:</b> the instance returned is a singleton.
+   */
   public static <K, V> ImmutableMultimap<K, V> of() {
     return ImmutableListMultimap.of();
   }
@@ -138,9 +147,9 @@ public static <K, V> Builder<K, V> builder() {
    */
   @DoNotMock
   public static class Builder<K, V> {
-    Map<K, Collection<V>> builderMap;
-    @NullableDecl Comparator<? super K> keyComparator;
-    @NullableDecl Comparator<? super V> valueComparator;
+    final Map<K, Collection<V>> builderMap;
+    @CheckForNull Comparator<? super K> keyComparator;
+    @CheckForNull Comparator<? super V> valueComparator;
 
     /**
      * Creates a new builder. The returned builder is equivalent to the builder generated by {@link
@@ -356,7 +365,11 @@ static class FieldSettersHolder {
   @CanIgnoreReturnValue
   @Deprecated
   @Override
-  public ImmutableCollection<V> removeAll(Object key) {
+  @DoNotCall("Always throws UnsupportedOperationException")
+  // DoNotCall wants this to be final, but we want to override it to return more specific types.
+  // Inheritance is closed, and all subtypes are @DoNotCall, so this is safe to suppress.
+  @SuppressWarnings("DoNotCall")
+  public ImmutableCollection<V> removeAll(@CheckForNull Object key) {
     throw new UnsupportedOperationException();
   }
 
@@ -369,6 +382,10 @@ public ImmutableCollection<V> removeAll(Object key) {
   @CanIgnoreReturnValue
   @Deprecated
   @Override
+  @DoNotCall("Always throws UnsupportedOperationException")
+  // DoNotCall wants this to be final, but we want to override it to return more specific types.
+  // Inheritance is closed, and all subtypes are @DoNotCall, so this is safe to suppress.
+  @SuppressWarnings("DoNotCall")
   public ImmutableCollection<V> replaceValues(K key, Iterable<? extends V> values) {
     throw new UnsupportedOperationException();
   }
@@ -381,7 +398,8 @@ public ImmutableCollection<V> replaceValues(K key, Iterable<? extends V> values)
    */
   @Deprecated
   @Override
-  public void clear() {
+  @DoNotCall("Always throws UnsupportedOperationException")
+  public final void clear() {
     throw new UnsupportedOperationException();
   }
 
@@ -410,7 +428,8 @@ public void clear() {
   @CanIgnoreReturnValue
   @Deprecated
   @Override
-  public boolean put(K key, V value) {
+  @DoNotCall("Always throws UnsupportedOperationException")
+  public final boolean put(K key, V value) {
     throw new UnsupportedOperationException();
   }
 
@@ -423,7 +442,8 @@ public boolean put(K key, V value) {
   @CanIgnoreReturnValue
   @Deprecated
   @Override
-  public boolean putAll(K key, Iterable<? extends V> values) {
+  @DoNotCall("Always throws UnsupportedOperationException")
+  public final boolean putAll(K key, Iterable<? extends V> values) {
     throw new UnsupportedOperationException();
   }
 
@@ -436,7 +456,8 @@ public boolean putAll(K key, Iterable<? extends V> values) {
   @CanIgnoreReturnValue
   @Deprecated
   @Override
-  public boolean putAll(Multimap<? extends K, ? extends V> multimap) {
+  @DoNotCall("Always throws UnsupportedOperationException")
+  public final boolean putAll(Multimap<? extends K, ? extends V> multimap) {
     throw new UnsupportedOperationException();
   }
 
@@ -449,7 +470,8 @@ public boolean putAll(Multimap<? extends K, ? extends V> multimap) {
   @CanIgnoreReturnValue
   @Deprecated
   @Override
-  public boolean remove(Object key, Object value) {
+  @DoNotCall("Always throws UnsupportedOperationException")
+  public final boolean remove(@CheckForNull Object key, @CheckForNull Object value) {
     throw new UnsupportedOperationException();
   }
 
@@ -466,12 +488,12 @@ boolean isPartialView() {
   // accessors
 
   @Override
-  public boolean containsKey(@NullableDecl Object key) {
+  public boolean containsKey(@CheckForNull Object key) {
     return map.containsKey(key);
   }
 
   @Override
-  public boolean containsValue(@NullableDecl Object value) {
+  public boolean containsValue(@CheckForNull Object value) {
     return value != null && super.containsValue(value);
   }
 
@@ -545,7 +567,7 @@ public int size() {
     }
 
     @Override
-    public boolean contains(Object object) {
+    public boolean contains(@CheckForNull Object object) {
       if (object instanceof Entry) {
         Entry<?, ?> entry = (Entry<?, ?>) object;
         return multimap.containsEntry(entry.getKey(), entry.getValue());
@@ -561,7 +583,7 @@ UnmodifiableIterator<Entry<K, V>> entryIterator() {
     return new UnmodifiableIterator<Entry<K, V>>() {
       final Iterator<? extends Entry<K, ? extends ImmutableCollection<V>>> asMapItr =
           map.entrySet().iterator();
-      K currentKey = null;
+      @CheckForNull K currentKey = null;
       Iterator<V> valueItr = Iterators.emptyIterator();
 
       @Override
@@ -576,7 +598,11 @@ public Entry<K, V> next() {
           currentKey = entry.getKey();
           valueItr = entry.getValue().iterator();
         }
-        return Maps.immutableEntry(currentKey, valueItr.next());
+        /*
+         * requireNonNull is safe: The first call to this method always enters the !hasNext() case
+         * and populates currentKey, after which it's never cleared.
+         */
+        return immutableEntry(requireNonNull(currentKey), valueItr.next());
       }
     };
   }
@@ -600,12 +626,12 @@ ImmutableMultiset<K> createKeys() {
   @WeakOuter
   class Keys extends ImmutableMultiset<K> {
     @Override
-    public boolean contains(@NullableDecl Object object) {
+    public boolean contains(@CheckForNull Object object) {
       return containsKey(object);
     }
 
     @Override
-    public int count(@NullableDecl Object element) {
+    public int count(@CheckForNull Object element) {
       Collection<V> values = map.get(element);
       return (values == null) ? 0 : values.size();
     }
@@ -694,7 +720,7 @@ private static final class Values<K, V> extends ImmutableCollection<V> {
     }
 
     @Override
-    public boolean contains(@NullableDecl Object object) {
+    public boolean contains(@CheckForNull Object object) {
       return multimap.containsValue(object);
     }
 
@@ -705,7 +731,7 @@ public UnmodifiableIterator<V> iterator() {
 
     @GwtIncompatible // not present in emulated superclass
     @Override
-    int copyIntoArray(Object[] dst, int offset) {
+    int copyIntoArray(@Nullable Object[] dst, int offset) {
       for (ImmutableCollection<V> valueCollection : multimap.map.values()) {
         offset = valueCollection.copyIntoArray(dst, offset);
       }
diff --git a/android/guava/src/com/google/common/collect/ImmutableMultiset.java b/android/guava/src/com/google/common/collect/ImmutableMultiset.java
index 7dc7daa8389a..ab281d4b3b3f 100644
--- a/android/guava/src/com/google/common/collect/ImmutableMultiset.java
+++ b/android/guava/src/com/google/common/collect/ImmutableMultiset.java
@@ -17,6 +17,7 @@
 package com.google.common.collect;
 
 import static com.google.common.base.Preconditions.checkNotNull;
+import static java.util.Objects.requireNonNull;
 
 import com.google.common.annotations.GwtCompatible;
 import com.google.common.annotations.GwtIncompatible;
@@ -29,7 +30,8 @@
 import java.util.Collection;
 import java.util.Iterator;
 import java.util.Set;
-import org.checkerframework.checker.nullness.compatqual.NullableDecl;
+import javax.annotation.CheckForNull;
+import org.checkerframework.checker.nullness.qual.Nullable;
 
 /**
  * A {@link Multiset} whose contents will never change, with many other important properties
@@ -40,7 +42,7 @@
  * element when the multiset was created.
  *
  * <p>See the Guava User Guide article on <a href=
- * "https://github.com/google/guava/wiki/ImmutableCollectionsExplained"> immutable collections</a>.
+ * "https://github.com/google/guava/wiki/ImmutableCollectionsExplained">immutable collections</a>.
  *
  * @author Jared Levy
  * @author Louis Wasserman
@@ -48,9 +50,14 @@
  */
 @GwtCompatible(serializable = true, emulated = true)
 @SuppressWarnings("serial") // we're overriding default serialization
+@ElementTypesAreNonnullByDefault
 public abstract class ImmutableMultiset<E> extends ImmutableMultisetGwtSerializationDependencies<E>
     implements Multiset<E> {
-  /** Returns the empty immutable multiset. */
+  /**
+   * Returns the empty immutable multiset.
+   *
+   * <p><b>Performance note:</b> the instance returned is a singleton.
+   */
   @SuppressWarnings("unchecked") // all supported methods are covariant
   public static <E> ImmutableMultiset<E> of() {
     return (ImmutableMultiset<E>) RegularImmutableMultiset.EMPTY;
@@ -62,7 +69,6 @@ public static <E> ImmutableMultiset<E> of() {
    * @throws NullPointerException if {@code element} is null
    * @since 6.0 (source-compatible since 2.0)
    */
-  @SuppressWarnings("unchecked") // generic array created but never written
   public static <E> ImmutableMultiset<E> of(E element) {
     return copyFromElements(element);
   }
@@ -73,7 +79,6 @@ public static <E> ImmutableMultiset<E> of(E element) {
    * @throws NullPointerException if any element is null
    * @since 6.0 (source-compatible since 2.0)
    */
-  @SuppressWarnings("unchecked") //
   public static <E> ImmutableMultiset<E> of(E e1, E e2) {
     return copyFromElements(e1, e2);
   }
@@ -85,7 +90,6 @@ public static <E> ImmutableMultiset<E> of(E e1, E e2) {
    * @throws NullPointerException if any element is null
    * @since 6.0 (source-compatible since 2.0)
    */
-  @SuppressWarnings("unchecked") //
   public static <E> ImmutableMultiset<E> of(E e1, E e2, E e3) {
     return copyFromElements(e1, e2, e3);
   }
@@ -97,7 +101,6 @@ public static <E> ImmutableMultiset<E> of(E e1, E e2, E e3) {
    * @throws NullPointerException if any element is null
    * @since 6.0 (source-compatible since 2.0)
    */
-  @SuppressWarnings("unchecked") //
   public static <E> ImmutableMultiset<E> of(E e1, E e2, E e3, E e4) {
     return copyFromElements(e1, e2, e3, e4);
   }
@@ -109,7 +112,6 @@ public static <E> ImmutableMultiset<E> of(E e1, E e2, E e3, E e4) {
    * @throws NullPointerException if any element is null
    * @since 6.0 (source-compatible since 2.0)
    */
-  @SuppressWarnings("unchecked") //
   public static <E> ImmutableMultiset<E> of(E e1, E e2, E e3, E e4, E e5) {
     return copyFromElements(e1, e2, e3, e4, e5);
   }
@@ -121,7 +123,6 @@ public static <E> ImmutableMultiset<E> of(E e1, E e2, E e3, E e4, E e5) {
    * @throws NullPointerException if any element is null
    * @since 6.0 (source-compatible since 2.0)
    */
-  @SuppressWarnings("unchecked") //
   public static <E> ImmutableMultiset<E> of(E e1, E e2, E e3, E e4, E e5, E e6, E... others) {
     return new Builder<E>().add(e1).add(e2).add(e3).add(e4).add(e5).add(e6).add(others).build();
   }
@@ -187,7 +188,7 @@ public UnmodifiableIterator<E> iterator() {
     final Iterator<Entry<E>> entryIterator = entrySet().iterator();
     return new UnmodifiableIterator<E>() {
       int remaining;
-      @NullableDecl E element;
+      @CheckForNull E element;
 
       @Override
       public boolean hasNext() {
@@ -202,12 +203,16 @@ public E next() {
           remaining = entry.getCount();
         }
         remaining--;
-        return element;
+        /*
+         * requireNonNull is safe because `remaining` starts at 0, forcing us to initialize
+         * `element` above. After that, we never clear it.
+         */
+        return requireNonNull(element);
       }
     };
   }
 
-  @LazyInit private transient ImmutableList<E> asList;
+  @LazyInit @CheckForNull private transient ImmutableList<E> asList;
 
   @Override
   public ImmutableList<E> asList() {
@@ -216,7 +221,7 @@ public ImmutableList<E> asList() {
   }
 
   @Override
-  public boolean contains(@NullableDecl Object object) {
+  public boolean contains(@CheckForNull Object object) {
     return count(object) > 0;
   }
 
@@ -244,7 +249,7 @@ public final int add(E element, int occurrences) {
   @Deprecated
   @Override
   @DoNotCall("Always throws UnsupportedOperationException")
-  public final int remove(Object element, int occurrences) {
+  public final int remove(@CheckForNull Object element, int occurrences) {
     throw new UnsupportedOperationException();
   }
 
@@ -278,7 +283,7 @@ public final boolean setCount(E element, int oldCount, int newCount) {
 
   @GwtIncompatible // not present in emulated superclass
   @Override
-  int copyIntoArray(Object[] dst, int offset) {
+  int copyIntoArray(@Nullable Object[] dst, int offset) {
     for (Multiset.Entry<E> entry : entrySet()) {
       Arrays.fill(dst, offset, offset + entry.getCount(), entry.getElement());
       offset += entry.getCount();
@@ -287,7 +292,7 @@ int copyIntoArray(Object[] dst, int offset) {
   }
 
   @Override
-  public boolean equals(@NullableDecl Object object) {
+  public boolean equals(@CheckForNull Object object) {
     return Multisets.equalsImpl(this, object);
   }
 
@@ -305,7 +310,7 @@ public String toString() {
   @Override
   public abstract ImmutableSet<E> elementSet();
 
-  @LazyInit private transient ImmutableSet<Entry<E>> entrySet;
+  @LazyInit @CheckForNull private transient ImmutableSet<Entry<E>> entrySet;
 
   @Override
   public ImmutableSet<Entry<E>> entrySet() {
@@ -337,7 +342,7 @@ public int size() {
     }
 
     @Override
-    public boolean contains(Object o) {
+    public boolean contains(@CheckForNull Object o) {
       if (o instanceof Entry) {
         Entry<?> entry = (Entry<?>) o;
         if (entry.getCount() <= 0) {
@@ -408,7 +413,12 @@ public static <E> Builder<E> builder() {
    * @since 2.0
    */
   public static class Builder<E> extends ImmutableCollection.Builder<E> {
-    ObjectCountHashMap<E> contents;
+    /*
+     * `contents` is null only for instances of the subclass, ImmutableSortedMultiset.Builder. That
+     * subclass overrides all the methods that access it here. Thus, all the methods here can safely
+     * assume that this field is non-null.
+     */
+    @CheckForNull ObjectCountHashMap<E> contents;
 
     /**
      * If build() has been called on the current contents multiset, we need to copy it on any future
@@ -479,6 +489,7 @@ public Builder<E> add(E... elements) {
      */
     @CanIgnoreReturnValue
     public Builder<E> addCopies(E element, int occurrences) {
+      requireNonNull(contents); // see the comment on the field
       if (occurrences == 0) {
         return this;
       }
@@ -504,6 +515,7 @@ public Builder<E> addCopies(E element, int occurrences) {
      */
     @CanIgnoreReturnValue
     public Builder<E> setCount(E element, int count) {
+      requireNonNull(contents); // see the comment on the field
       if (count == 0 && !isLinkedHash) {
         contents = new ObjectCountLinkedHashMap<E>(contents);
         isLinkedHash = true;
@@ -533,6 +545,7 @@ public Builder<E> setCount(E element, int count) {
     @CanIgnoreReturnValue
     @Override
     public Builder<E> addAll(Iterable<? extends E> elements) {
+      requireNonNull(contents); // see the comment on the field
       if (elements instanceof Multiset) {
         Multiset<? extends E> multiset = Multisets.cast(elements);
         ObjectCountHashMap<? extends E> backingMap = tryGetMap(multiset);
@@ -573,7 +586,7 @@ public Builder<E> addAll(Iterator<? extends E> elements) {
      * efficient to iterate over it by index rather than an entry iterator, which will need to
      * allocate an object for each entry, so we check for that.
      */
-    @NullableDecl
+    @CheckForNull
     static <T> ObjectCountHashMap<T> tryGetMap(Iterable<T> multiset) {
       if (multiset instanceof RegularImmutableMultiset) {
         return ((RegularImmutableMultiset<T>) multiset).contents;
@@ -590,6 +603,7 @@ static <T> ObjectCountHashMap<T> tryGetMap(Iterable<T> multiset) {
      */
     @Override
     public ImmutableMultiset<E> build() {
+      requireNonNull(contents); // see the comment on the field
       if (contents.size() == 0) {
         return of();
       }
diff --git a/android/guava/src/com/google/common/collect/ImmutableMultisetGwtSerializationDependencies.java b/android/guava/src/com/google/common/collect/ImmutableMultisetGwtSerializationDependencies.java
index a8b1899d280c..2469a188a2a6 100644
--- a/android/guava/src/com/google/common/collect/ImmutableMultisetGwtSerializationDependencies.java
+++ b/android/guava/src/com/google/common/collect/ImmutableMultisetGwtSerializationDependencies.java
@@ -37,4 +37,5 @@
  * and make types non-final.
  */
 @GwtCompatible(emulated = true)
+@ElementTypesAreNonnullByDefault
 abstract class ImmutableMultisetGwtSerializationDependencies<E> extends ImmutableCollection<E> {}
diff --git a/android/guava/src/com/google/common/collect/ImmutableRangeMap.java b/android/guava/src/com/google/common/collect/ImmutableRangeMap.java
index 694a380e5035..8a477961989d 100644
--- a/android/guava/src/com/google/common/collect/ImmutableRangeMap.java
+++ b/android/guava/src/com/google/common/collect/ImmutableRangeMap.java
@@ -31,7 +31,7 @@
 import java.util.Map;
 import java.util.Map.Entry;
 import java.util.NoSuchElementException;
-import org.checkerframework.checker.nullness.compatqual.NullableDecl;
+import javax.annotation.CheckForNull;
 
 /**
  * A {@link RangeMap} whose contents will never change, with many other important properties
@@ -42,12 +42,17 @@
  */
 @Beta
 @GwtIncompatible // NavigableMap
+@ElementTypesAreNonnullByDefault
 public class ImmutableRangeMap<K extends Comparable<?>, V> implements RangeMap<K, V>, Serializable {
 
   private static final ImmutableRangeMap<Comparable<?>, Object> EMPTY =
       new ImmutableRangeMap<>(ImmutableList.<Range<Comparable<?>>>of(), ImmutableList.of());
 
-  /** Returns an empty immutable range map. */
+  /**
+   * Returns an empty immutable range map.
+   *
+   * <p><b>Performance note:</b> the instance returned is a singleton.
+   */
   @SuppressWarnings("unchecked")
   public static <K extends Comparable<?>, V> ImmutableRangeMap<K, V> of() {
     return (ImmutableRangeMap<K, V>) EMPTY;
@@ -156,7 +161,7 @@ public ImmutableRangeMap<K, V> build() {
   }
 
   @Override
-  @NullableDecl
+  @CheckForNull
   public V get(K key) {
     int index =
         SortedLists.binarySearch(
@@ -174,7 +179,7 @@ public V get(K key) {
   }
 
   @Override
-  @NullableDecl
+  @CheckForNull
   public Entry<Range<K>, V> getEntry(K key) {
     int index =
         SortedLists.binarySearch(
@@ -353,7 +358,7 @@ public int hashCode() {
   }
 
   @Override
-  public boolean equals(@NullableDecl Object o) {
+  public boolean equals(@CheckForNull Object o) {
     if (o instanceof RangeMap) {
       RangeMap<?, ?> rangeMap = (RangeMap<?, ?>) o;
       return asMapOfRanges().equals(rangeMap.asMapOfRanges());
diff --git a/android/guava/src/com/google/common/collect/ImmutableRangeSet.java b/android/guava/src/com/google/common/collect/ImmutableRangeSet.java
index 8c1946fa1eef..a0eb5b5efb08 100644
--- a/android/guava/src/com/google/common/collect/ImmutableRangeSet.java
+++ b/android/guava/src/com/google/common/collect/ImmutableRangeSet.java
@@ -20,6 +20,7 @@
 import static com.google.common.collect.SortedLists.KeyAbsentBehavior.NEXT_HIGHER;
 import static com.google.common.collect.SortedLists.KeyAbsentBehavior.NEXT_LOWER;
 import static com.google.common.collect.SortedLists.KeyPresentBehavior.ANY_PRESENT;
+import static java.util.Objects.requireNonNull;
 
 import com.google.common.annotations.Beta;
 import com.google.common.annotations.GwtIncompatible;
@@ -35,7 +36,7 @@
 import java.util.List;
 import java.util.NoSuchElementException;
 import java.util.Set;
-import org.checkerframework.checker.nullness.compatqual.NullableDecl;
+import javax.annotation.CheckForNull;
 
 /**
  * A {@link RangeSet} whose contents will never change, with many other important properties
@@ -46,6 +47,7 @@
  */
 @Beta
 @GwtIncompatible
+@ElementTypesAreNonnullByDefault
 public final class ImmutableRangeSet<C extends Comparable> extends AbstractRangeSet<C>
     implements Serializable {
 
@@ -55,7 +57,11 @@ public final class ImmutableRangeSet<C extends Comparable> extends AbstractRange
   private static final ImmutableRangeSet<Comparable<?>> ALL =
       new ImmutableRangeSet<>(ImmutableList.of(Range.<Comparable<?>>all()));
 
-  /** Returns an empty immutable range set. */
+  /**
+   * Returns an empty immutable range set.
+   *
+   * <p><b>Performance note:</b> the instance returned is a singleton.
+   */
   @SuppressWarnings("unchecked")
   public static <C extends Comparable> ImmutableRangeSet<C> of() {
     return (ImmutableRangeSet<C>) EMPTY;
@@ -169,6 +175,7 @@ public boolean encloses(Range<C> otherRange) {
   }
 
   @Override
+  @CheckForNull
   public Range<C> rangeContaining(C value) {
     int index =
         SortedLists.binarySearch(
@@ -292,7 +299,7 @@ public ImmutableSet<Range<C>> asDescendingSetOfRanges() {
     return new RegularImmutableSortedSet<>(ranges.reverse(), Range.<C>rangeLexOrdering().reverse());
   }
 
-  @LazyInit private transient ImmutableRangeSet<C> complement;
+  @LazyInit @CheckForNull private transient ImmutableRangeSet<C> complement;
 
   private final class ComplementRanges extends ImmutableList<Range<C>> {
     // True if the "positive" range set is empty or bounded below.
@@ -534,7 +541,7 @@ private final class AsSet extends ImmutableSortedSet<C> {
       this.domain = domain;
     }
 
-    @NullableDecl private transient Integer size;
+    @CheckForNull private transient Integer size;
 
     @Override
     public int size() {
@@ -560,6 +567,7 @@ public UnmodifiableIterator<C> iterator() {
         Iterator<C> elemItr = Iterators.emptyIterator();
 
         @Override
+        @CheckForNull
         protected C computeNext() {
           while (!elemItr.hasNext()) {
             if (rangeItr.hasNext()) {
@@ -581,6 +589,7 @@ public UnmodifiableIterator<C> descendingIterator() {
         Iterator<C> elemItr = Iterators.emptyIterator();
 
         @Override
+        @CheckForNull
         protected C computeNext() {
           while (!elemItr.hasNext()) {
             if (rangeItr.hasNext()) {
@@ -621,7 +630,7 @@ ImmutableSortedSet<C> tailSetImpl(C fromElement, boolean inclusive) {
     }
 
     @Override
-    public boolean contains(@NullableDecl Object o) {
+    public boolean contains(@CheckForNull Object o) {
       if (o == null) {
         return false;
       }
@@ -635,10 +644,10 @@ public boolean contains(@NullableDecl Object o) {
     }
 
     @Override
-    int indexOf(Object target) {
+    int indexOf(@CheckForNull Object target) {
       if (contains(target)) {
         @SuppressWarnings("unchecked") // if it's contained, it's definitely a C
-        C c = (C) target;
+        C c = (C) requireNonNull(target);
         long total = 0;
         for (Range<C> range : ranges) {
           if (range.contains(c)) {
diff --git a/android/guava/src/com/google/common/collect/ImmutableSet.java b/android/guava/src/com/google/common/collect/ImmutableSet.java
index b2519819bf3b..1ff54e205baf 100644
--- a/android/guava/src/com/google/common/collect/ImmutableSet.java
+++ b/android/guava/src/com/google/common/collect/ImmutableSet.java
@@ -20,6 +20,7 @@
 import static com.google.common.base.Preconditions.checkNotNull;
 import static com.google.common.collect.CollectPreconditions.checkNonnegative;
 import static com.google.common.collect.ObjectArrays.checkElementNotNull;
+import static java.util.Objects.requireNonNull;
 
 import com.google.common.annotations.Beta;
 import com.google.common.annotations.GwtCompatible;
@@ -35,7 +36,8 @@
 import java.util.Iterator;
 import java.util.Set;
 import java.util.SortedSet;
-import org.checkerframework.checker.nullness.compatqual.NullableDecl;
+import javax.annotation.CheckForNull;
+import org.checkerframework.checker.nullness.qual.Nullable;
 
 /**
  * A {@link Set} whose contents will never change, with many other important properties detailed at
@@ -45,10 +47,13 @@
  */
 @GwtCompatible(serializable = true, emulated = true)
 @SuppressWarnings("serial") // we're overriding default serialization
+@ElementTypesAreNonnullByDefault
 public abstract class ImmutableSet<E> extends ImmutableCollection<E> implements Set<E> {
   /**
    * Returns the empty immutable set. Preferred over {@link Collections#emptySet} for code
    * consistency, and because the return type conveys the immutability guarantee.
+   *
+   * <p><b>Performance note:</b> the instance returned is a singleton.
    */
   @SuppressWarnings({"unchecked"}) // fully variant implementation (never actually produces any Es)
   public static <E> ImmutableSet<E> of() {
@@ -138,13 +143,14 @@ public static <E> ImmutableSet<E> of(E e1, E e2, E e3, E e4, E e5, E e6, E... ot
    *
    * @throws NullPointerException if any of the first {@code n} elements of {@code elements} is null
    */
-  private static <E> ImmutableSet<E> construct(int n, Object... elements) {
+  private static <E> ImmutableSet<E> construct(int n, @Nullable Object... elements) {
     switch (n) {
       case 0:
         return of();
       case 1:
         @SuppressWarnings("unchecked") // safe; elements contains only E's
-        E elem = (E) elements[0];
+        // requireNonNull is safe because the first `n` elements are non-null.
+        E elem = (E) requireNonNull(elements[0]);
         return of(elem);
       default:
         // continue below to handle the general case
@@ -175,12 +181,14 @@ private static <E> ImmutableSet<E> construct(int n, Object... elements) {
     if (uniques == 1) {
       // There is only one element or elements are all duplicates
       @SuppressWarnings("unchecked") // we are careful to only pass in E
-      E element = (E) elements[0];
-      return new SingletonImmutableSet<E>(element, hashCode);
+      // requireNonNull is safe because the first `uniques` elements are non-null.
+      E element = (E) requireNonNull(elements[0]);
+      return new SingletonImmutableSet<E>(element);
     } else if (chooseTableSize(uniques) < tableSize / 2) {
       // Resize the table when the array includes too many duplicates.
       return construct(uniques, elements);
     } else {
+      @Nullable
       Object[] uniqueElements =
           shouldTrim(uniques, elements.length) ? Arrays.copyOf(elements, uniques) : elements;
       return new RegularImmutableSet<E>(uniqueElements, hashCode, table, mask, uniques);
@@ -315,7 +323,7 @@ boolean isHashCodeFast() {
   }
 
   @Override
-  public boolean equals(@NullableDecl Object object) {
+  public boolean equals(@CheckForNull Object object) {
     if (object == this) {
       return true;
     }
@@ -338,7 +346,7 @@ public int hashCode() {
   @Override
   public abstract UnmodifiableIterator<E> iterator();
 
-  @LazyInit @RetainedWith @NullableDecl private transient ImmutableList<E> asList;
+  @LazyInit @RetainedWith @CheckForNull private transient ImmutableList<E> asList;
 
   @Override
   public ImmutableList<E> asList() {
@@ -421,7 +429,7 @@ public static <E> Builder<E> builderWithExpectedSize(int expectedSize) {
    * @since 2.0
    */
   public static class Builder<E> extends ImmutableCollection.ArrayBasedBuilder<E> {
-    @NullableDecl @VisibleForTesting Object[] hashTable;
+    @VisibleForTesting @CheckForNull @Nullable Object[] hashTable;
     private int hashCode;
 
     /**
@@ -434,7 +442,7 @@ public Builder() {
 
     Builder(int capacity) {
       super(capacity);
-      this.hashTable = new Object[chooseTableSize(capacity)];
+      this.hashTable = new @Nullable Object[chooseTableSize(capacity)];
     }
 
     /**
@@ -482,6 +490,7 @@ public Builder<E> add(E... elements) {
     }
 
     private void addDeduping(E element) {
+      requireNonNull(hashTable); // safe because we check for null before calling this method
       int mask = hashTable.length - 1;
       int hash = element.hashCode();
       for (int i = Hashing.smear(hash); ; i++) {
@@ -543,7 +552,8 @@ public Builder<E> addAll(Iterator<? extends E> elements) {
     Builder<E> combine(Builder<E> other) {
       if (hashTable != null) {
         for (int i = 0; i < other.size; ++i) {
-          add((E) other.contents[i]);
+          // requireNonNull is safe because the first `size` elements are non-null.
+          add((E) requireNonNull(other.contents[i]));
         }
       } else {
         addAll(other.contents, other.size);
@@ -561,10 +571,15 @@ public ImmutableSet<E> build() {
         case 0:
           return of();
         case 1:
-          return (ImmutableSet<E>) of(contents[0]);
+          /*
+           * requireNonNull is safe because we ensure that the first `size` elements have been
+           * populated.
+           */
+          return (ImmutableSet<E>) of(requireNonNull(contents[0]));
         default:
           ImmutableSet<E> result;
           if (hashTable != null && chooseTableSize(size) == hashTable.length) {
+            @Nullable
             Object[] uniqueElements =
                 shouldTrim(size, contents.length) ? Arrays.copyOf(contents, size) : contents;
             result =
diff --git a/android/guava/src/com/google/common/collect/ImmutableSetMultimap.java b/android/guava/src/com/google/common/collect/ImmutableSetMultimap.java
index 99267da25ff8..1f655e27a177 100644
--- a/android/guava/src/com/google/common/collect/ImmutableSetMultimap.java
+++ b/android/guava/src/com/google/common/collect/ImmutableSetMultimap.java
@@ -36,23 +36,32 @@
 import java.util.Comparator;
 import java.util.Map;
 import java.util.Map.Entry;
-import org.checkerframework.checker.nullness.compatqual.NullableDecl;
+import javax.annotation.CheckForNull;
 
 /**
  * A {@link SetMultimap} whose contents will never change, with many other important properties
  * detailed at {@link ImmutableCollection}.
  *
+ * <p><b>Warning:</b> As in all {@link SetMultimap}s, do not modify either a key <i>or a value</i>
+ * of a {@code ImmutableSetMultimap} in a way that affects its {@link Object#equals} behavior.
+ * Undefined behavior and bugs will result.
+ *
  * <p>See the Guava User Guide article on <a href=
- * "https://github.com/google/guava/wiki/ImmutableCollectionsExplained"> immutable collections</a>.
+ * "https://github.com/google/guava/wiki/ImmutableCollectionsExplained">immutable collections</a>.
  *
  * @author Mike Ward
  * @since 2.0
  */
 @GwtCompatible(serializable = true, emulated = true)
+@ElementTypesAreNonnullByDefault
 public class ImmutableSetMultimap<K, V> extends ImmutableMultimap<K, V>
     implements SetMultimap<K, V> {
 
-  /** Returns the empty multimap. */
+  /**
+   * Returns the empty multimap.
+   *
+   * <p><b>Performance note:</b> the instance returned is a singleton.
+   */
   // Casting is safe because the multimap will never hold any elements.
   @SuppressWarnings("unchecked")
   public static <K, V> ImmutableSetMultimap<K, V> of() {
@@ -280,7 +289,8 @@ public static <K, V> ImmutableSetMultimap<K, V> copyOf(
   }
 
   private static <K, V> ImmutableSetMultimap<K, V> copyOf(
-      Multimap<? extends K, ? extends V> multimap, Comparator<? super V> valueComparator) {
+      Multimap<? extends K, ? extends V> multimap,
+      @CheckForNull Comparator<? super V> valueComparator) {
     checkNotNull(multimap); // eager for GWT
     if (multimap.isEmpty() && valueComparator == null) {
       return of();
@@ -315,7 +325,7 @@ public static <K, V> ImmutableSetMultimap<K, V> copyOf(
   /** Creates an ImmutableSetMultimap from an asMap.entrySet. */
   static <K, V> ImmutableSetMultimap<K, V> fromMapEntries(
       Collection<? extends Map.Entry<? extends K, ? extends Collection<? extends V>>> mapEntries,
-      @NullableDecl Comparator<? super V> valueComparator) {
+      @CheckForNull Comparator<? super V> valueComparator) {
     if (mapEntries.isEmpty()) {
       return of();
     }
@@ -333,7 +343,7 @@ static <K, V> ImmutableSetMultimap<K, V> fromMapEntries(
       }
     }
 
-    return new ImmutableSetMultimap<>(builder.build(), size, valueComparator);
+    return new ImmutableSetMultimap<>(builder.buildOrThrow(), size, valueComparator);
   }
 
   /**
@@ -345,7 +355,7 @@ static <K, V> ImmutableSetMultimap<K, V> fromMapEntries(
   ImmutableSetMultimap(
       ImmutableMap<K, ImmutableSet<V>> map,
       int size,
-      @NullableDecl Comparator<? super V> valueComparator) {
+      @CheckForNull Comparator<? super V> valueComparator) {
     super(map, size);
     this.emptySet = emptySet(valueComparator);
   }
@@ -358,13 +368,13 @@ static <K, V> ImmutableSetMultimap<K, V> fromMapEntries(
    * parameters used to build this multimap.
    */
   @Override
-  public ImmutableSet<V> get(@NullableDecl K key) {
+  public ImmutableSet<V> get(K key) {
     // This cast is safe as its type is known in constructor.
     ImmutableSet<V> set = (ImmutableSet<V>) map.get(key);
     return MoreObjects.firstNonNull(set, emptySet);
   }
 
-  @LazyInit @RetainedWith @NullableDecl private transient ImmutableSetMultimap<V, K> inverse;
+  @LazyInit @RetainedWith @CheckForNull private transient ImmutableSetMultimap<V, K> inverse;
 
   /**
    * {@inheritDoc}
@@ -399,7 +409,7 @@ private ImmutableSetMultimap<V, K> invert() {
   @Deprecated
   @Override
   @DoNotCall("Always throws UnsupportedOperationException")
-  public final ImmutableSet<V> removeAll(Object key) {
+  public final ImmutableSet<V> removeAll(@CheckForNull Object key) {
     throw new UnsupportedOperationException();
   }
 
@@ -417,7 +427,7 @@ public final ImmutableSet<V> replaceValues(K key, Iterable<? extends V> values)
     throw new UnsupportedOperationException();
   }
 
-  @LazyInit @RetainedWith @NullableDecl private transient ImmutableSet<Entry<K, V>> entries;
+  @LazyInit @RetainedWith @CheckForNull private transient ImmutableSet<Entry<K, V>> entries;
 
   /**
    * Returns an immutable collection of all key-value pairs in the multimap. Its iterator traverses
@@ -437,7 +447,7 @@ private static final class EntrySet<K, V> extends ImmutableSet<Entry<K, V>> {
     }
 
     @Override
-    public boolean contains(@NullableDecl Object object) {
+    public boolean contains(@CheckForNull Object object) {
       if (object instanceof Entry) {
         Entry<?, ?> entry = (Entry<?, ?>) object;
         return multimap.containsEntry(entry.getKey(), entry.getValue());
@@ -462,20 +472,20 @@ boolean isPartialView() {
   }
 
   private static <V> ImmutableSet<V> valueSet(
-      @NullableDecl Comparator<? super V> valueComparator, Collection<? extends V> values) {
+      @CheckForNull Comparator<? super V> valueComparator, Collection<? extends V> values) {
     return (valueComparator == null)
         ? ImmutableSet.copyOf(values)
         : ImmutableSortedSet.copyOf(valueComparator, values);
   }
 
-  private static <V> ImmutableSet<V> emptySet(@NullableDecl Comparator<? super V> valueComparator) {
+  private static <V> ImmutableSet<V> emptySet(@CheckForNull Comparator<? super V> valueComparator) {
     return (valueComparator == null)
         ? ImmutableSet.<V>of()
         : ImmutableSortedSet.<V>emptySet(valueComparator);
   }
 
   private static <V> ImmutableSet.Builder<V> valuesBuilder(
-      @NullableDecl Comparator<? super V> valueComparator) {
+      @CheckForNull Comparator<? super V> valueComparator) {
     return (valueComparator == null)
         ? new ImmutableSet.Builder<V>()
         : new ImmutableSortedSet.Builder<V>(valueComparator);
@@ -492,7 +502,7 @@ private void writeObject(ObjectOutputStream stream) throws IOException {
     Serialization.writeMultimap(this, stream);
   }
 
-  @NullableDecl
+  @CheckForNull
   Comparator<? super V> valueComparator() {
     return emptySet instanceof ImmutableSortedSet
         ? ((ImmutableSortedSet<V>) emptySet).comparator()
@@ -539,7 +549,7 @@ private void readObject(ObjectInputStream stream) throws IOException, ClassNotFo
 
     ImmutableMap<Object, ImmutableSet<Object>> tmpMap;
     try {
-      tmpMap = builder.build();
+      tmpMap = builder.buildOrThrow();
     } catch (IllegalArgumentException e) {
       throw (InvalidObjectException) new InvalidObjectException(e.getMessage()).initCause(e);
     }
diff --git a/android/guava/src/com/google/common/collect/ImmutableSortedMap.java b/android/guava/src/com/google/common/collect/ImmutableSortedMap.java
index 15be18821a46..709504eb28f1 100644
--- a/android/guava/src/com/google/common/collect/ImmutableSortedMap.java
+++ b/android/guava/src/com/google/common/collect/ImmutableSortedMap.java
@@ -20,6 +20,7 @@
 import static com.google.common.base.Preconditions.checkNotNull;
 import static com.google.common.collect.CollectPreconditions.checkEntryNotNull;
 import static com.google.common.collect.Maps.keyOrNull;
+import static java.util.Objects.requireNonNull;
 
 import com.google.common.annotations.Beta;
 import com.google.common.annotations.GwtCompatible;
@@ -32,7 +33,8 @@
 import java.util.NavigableMap;
 import java.util.SortedMap;
 import java.util.TreeMap;
-import org.checkerframework.checker.nullness.compatqual.NullableDecl;
+import javax.annotation.CheckForNull;
+import org.checkerframework.checker.nullness.qual.Nullable;
 
 /**
  * A {@link NavigableMap} whose contents will never change, with many other important properties
@@ -45,13 +47,14 @@
  * not correctly obey its specification.
  *
  * <p>See the Guava User Guide article on <a href=
- * "https://github.com/google/guava/wiki/ImmutableCollectionsExplained"> immutable collections</a>.
+ * "https://github.com/google/guava/wiki/ImmutableCollectionsExplained">immutable collections</a>.
  *
  * @author Jared Levy
  * @author Louis Wasserman
  * @since 2.0 (implements {@code NavigableMap} since 12.0)
  */
 @GwtCompatible(serializable = true, emulated = true)
+@ElementTypesAreNonnullByDefault
 public final class ImmutableSortedMap<K, V> extends ImmutableSortedMapFauxverideShim<K, V>
     implements NavigableMap<K, V> {
 
@@ -74,7 +77,11 @@ static <K, V> ImmutableSortedMap<K, V> emptyMap(Comparator<? super K> comparator
     }
   }
 
-  /** Returns the empty sorted map. */
+  /**
+   * Returns the empty sorted map.
+   *
+   * <p><b>Performance note:</b> the instance returned is a singleton.
+   */
   @SuppressWarnings("unchecked")
   // unsafe, comparator() returns a comparator on the specified type
   // TODO(kevinb): evaluate whether or not of().comparator() should return null
@@ -103,7 +110,7 @@ private static <K, V> ImmutableSortedMap<K, V> of(Comparator<? super K> comparat
   @SuppressWarnings("unchecked")
   public static <K extends Comparable<? super K>, V> ImmutableSortedMap<K, V> of(
       K k1, V v1, K k2, V v2) {
-    return ofEntries(entryOf(k1, v1), entryOf(k2, v2));
+    return fromEntries(entryOf(k1, v1), entryOf(k2, v2));
   }
 
   /**
@@ -115,7 +122,7 @@ public static <K extends Comparable<? super K>, V> ImmutableSortedMap<K, V> of(
   @SuppressWarnings("unchecked")
   public static <K extends Comparable<? super K>, V> ImmutableSortedMap<K, V> of(
       K k1, V v1, K k2, V v2, K k3, V v3) {
-    return ofEntries(entryOf(k1, v1), entryOf(k2, v2), entryOf(k3, v3));
+    return fromEntries(entryOf(k1, v1), entryOf(k2, v2), entryOf(k3, v3));
   }
 
   /**
@@ -127,7 +134,7 @@ public static <K extends Comparable<? super K>, V> ImmutableSortedMap<K, V> of(
   @SuppressWarnings("unchecked")
   public static <K extends Comparable<? super K>, V> ImmutableSortedMap<K, V> of(
       K k1, V v1, K k2, V v2, K k3, V v3, K k4, V v4) {
-    return ofEntries(entryOf(k1, v1), entryOf(k2, v2), entryOf(k3, v3), entryOf(k4, v4));
+    return fromEntries(entryOf(k1, v1), entryOf(k2, v2), entryOf(k3, v3), entryOf(k4, v4));
   }
 
   /**
@@ -139,13 +146,164 @@ public static <K extends Comparable<? super K>, V> ImmutableSortedMap<K, V> of(
   @SuppressWarnings("unchecked")
   public static <K extends Comparable<? super K>, V> ImmutableSortedMap<K, V> of(
       K k1, V v1, K k2, V v2, K k3, V v3, K k4, V v4, K k5, V v5) {
-    return ofEntries(
+    return fromEntries(
         entryOf(k1, v1), entryOf(k2, v2), entryOf(k3, v3), entryOf(k4, v4), entryOf(k5, v5));
   }
 
-  private static <K extends Comparable<? super K>, V> ImmutableSortedMap<K, V> ofEntries(
-      Entry<K, V>... entries) {
-    return fromEntries(Ordering.natural(), false, entries, entries.length);
+  /**
+   * Returns an immutable sorted map containing the given entries, sorted by the natural ordering of
+   * their keys.
+   *
+   * @throws IllegalArgumentException if any two keys are equal according to their natural ordering
+   * @since 31.0
+   */
+  @SuppressWarnings("unchecked")
+  public static <K extends Comparable<? super K>, V> ImmutableSortedMap<K, V> of(
+      K k1, V v1, K k2, V v2, K k3, V v3, K k4, V v4, K k5, V v5, K k6, V v6) {
+    return fromEntries(
+        entryOf(k1, v1),
+        entryOf(k2, v2),
+        entryOf(k3, v3),
+        entryOf(k4, v4),
+        entryOf(k5, v5),
+        entryOf(k6, v6));
+  }
+
+  /**
+   * Returns an immutable sorted map containing the given entries, sorted by the natural ordering of
+   * their keys.
+   *
+   * @throws IllegalArgumentException if any two keys are equal according to their natural ordering
+   * @since 31.0
+   */
+  @SuppressWarnings("unchecked")
+  public static <K extends Comparable<? super K>, V> ImmutableSortedMap<K, V> of(
+      K k1, V v1, K k2, V v2, K k3, V v3, K k4, V v4, K k5, V v5, K k6, V v6, K k7, V v7) {
+    return fromEntries(
+        entryOf(k1, v1),
+        entryOf(k2, v2),
+        entryOf(k3, v3),
+        entryOf(k4, v4),
+        entryOf(k5, v5),
+        entryOf(k6, v6),
+        entryOf(k7, v7));
+  }
+
+  /**
+   * Returns an immutable sorted map containing the given entries, sorted by the natural ordering of
+   * their keys.
+   *
+   * @throws IllegalArgumentException if any two keys are equal according to their natural ordering
+   * @since 31.0
+   */
+  @SuppressWarnings("unchecked")
+  public static <K extends Comparable<? super K>, V> ImmutableSortedMap<K, V> of(
+      K k1,
+      V v1,
+      K k2,
+      V v2,
+      K k3,
+      V v3,
+      K k4,
+      V v4,
+      K k5,
+      V v5,
+      K k6,
+      V v6,
+      K k7,
+      V v7,
+      K k8,
+      V v8) {
+    return fromEntries(
+        entryOf(k1, v1),
+        entryOf(k2, v2),
+        entryOf(k3, v3),
+        entryOf(k4, v4),
+        entryOf(k5, v5),
+        entryOf(k6, v6),
+        entryOf(k7, v7),
+        entryOf(k8, v8));
+  }
+
+  /**
+   * Returns an immutable sorted map containing the given entries, sorted by the natural ordering of
+   * their keys.
+   *
+   * @throws IllegalArgumentException if any two keys are equal according to their natural ordering
+   * @since 31.0
+   */
+  @SuppressWarnings("unchecked")
+  public static <K extends Comparable<? super K>, V> ImmutableSortedMap<K, V> of(
+      K k1,
+      V v1,
+      K k2,
+      V v2,
+      K k3,
+      V v3,
+      K k4,
+      V v4,
+      K k5,
+      V v5,
+      K k6,
+      V v6,
+      K k7,
+      V v7,
+      K k8,
+      V v8,
+      K k9,
+      V v9) {
+    return fromEntries(
+        entryOf(k1, v1),
+        entryOf(k2, v2),
+        entryOf(k3, v3),
+        entryOf(k4, v4),
+        entryOf(k5, v5),
+        entryOf(k6, v6),
+        entryOf(k7, v7),
+        entryOf(k8, v8),
+        entryOf(k9, v9));
+  }
+
+  /**
+   * Returns an immutable sorted map containing the given entries, sorted by the natural ordering of
+   * their keys.
+   *
+   * @throws IllegalArgumentException if any two keys are equal according to their natural ordering
+   * @since 31.0
+   */
+  @SuppressWarnings("unchecked")
+  public static <K extends Comparable<? super K>, V> ImmutableSortedMap<K, V> of(
+      K k1,
+      V v1,
+      K k2,
+      V v2,
+      K k3,
+      V v3,
+      K k4,
+      V v4,
+      K k5,
+      V v5,
+      K k6,
+      V v6,
+      K k7,
+      V v7,
+      K k8,
+      V v8,
+      K k9,
+      V v9,
+      K k10,
+      V v10) {
+    return fromEntries(
+        entryOf(k1, v1),
+        entryOf(k2, v2),
+        entryOf(k3, v3),
+        entryOf(k4, v4),
+        entryOf(k5, v5),
+        entryOf(k6, v6),
+        entryOf(k7, v7),
+        entryOf(k8, v8),
+        entryOf(k9, v9),
+        entryOf(k10, v10));
   }
 
   /**
@@ -275,6 +433,11 @@ private static <K, V> ImmutableSortedMap<K, V> copyOfInternal(
     return fromEntries(comparator, sameComparator, map.entrySet());
   }
 
+  private static <K extends Comparable<? super K>, V> ImmutableSortedMap<K, V> fromEntries(
+      Entry<K, V>... entries) {
+    return fromEntries(Ordering.natural(), false, entries, entries.length);
+  }
+
   /**
    * Accepts a collection of possibly-null entries. If {@code sameComparator}, then it is assumed
    * that they do not need to be sorted or checked for dupes.
@@ -294,22 +457,25 @@ private static <K, V> ImmutableSortedMap<K, V> fromEntries(
   private static <K, V> ImmutableSortedMap<K, V> fromEntries(
       final Comparator<? super K> comparator,
       boolean sameComparator,
-      Entry<K, V>[] entryArray,
+      @Nullable Entry<K, V>[] entryArray,
       int size) {
     switch (size) {
       case 0:
         return emptyMap(comparator);
       case 1:
-        return ImmutableSortedMap.<K, V>of(
-            comparator, entryArray[0].getKey(), entryArray[0].getValue());
+        // requireNonNull is safe because the first `size` elements have been filled in.
+        Entry<K, V> onlyEntry = requireNonNull(entryArray[0]);
+        return of(comparator, onlyEntry.getKey(), onlyEntry.getValue());
       default:
         Object[] keys = new Object[size];
         Object[] values = new Object[size];
         if (sameComparator) {
           // Need to check for nulls, but don't need to sort or validate.
           for (int i = 0; i < size; i++) {
-            Object key = entryArray[i].getKey();
-            Object value = entryArray[i].getValue();
+            // requireNonNull is safe because the first `size` elements have been filled in.
+            Entry<K, V> entry = requireNonNull(entryArray[i]);
+            Object key = entry.getKey();
+            Object value = entry.getValue();
             checkEntryNotNull(key, value);
             keys[i] = key;
             values[i] = value;
@@ -322,24 +488,31 @@ private static <K, V> ImmutableSortedMap<K, V> fromEntries(
               entryArray,
               0,
               size,
-              new Comparator<Entry<K, V>>() {
+              new Comparator<@Nullable Entry<K, V>>() {
                 @Override
-                public int compare(Entry<K, V> e1, Entry<K, V> e2) {
+                public int compare(@CheckForNull Entry<K, V> e1, @CheckForNull Entry<K, V> e2) {
+                  // requireNonNull is safe because the first `size` elements have been filled in.
+                  requireNonNull(e1);
+                  requireNonNull(e2);
                   return comparator.compare(e1.getKey(), e2.getKey());
                 }
               });
-          K prevKey = entryArray[0].getKey();
+          // requireNonNull is safe because the first `size` elements have been filled in.
+          Entry<K, V> firstEntry = requireNonNull(entryArray[0]);
+          K prevKey = firstEntry.getKey();
           keys[0] = prevKey;
-          values[0] = entryArray[0].getValue();
+          values[0] = firstEntry.getValue();
           checkEntryNotNull(keys[0], values[0]);
           for (int i = 1; i < size; i++) {
-            K key = entryArray[i].getKey();
-            V value = entryArray[i].getValue();
+            // requireNonNull is safe because the first `size` elements have been filled in.
+            Entry<K, V> prevEntry = requireNonNull(entryArray[i - 1]);
+            Entry<K, V> entry = requireNonNull(entryArray[i]);
+            K key = entry.getKey();
+            V value = entry.getValue();
             checkEntryNotNull(key, value);
             keys[i] = key;
             values[i] = value;
-            checkNoConflict(
-                comparator.compare(prevKey, key) != 0, "key", entryArray[i - 1], entryArray[i]);
+            checkNoConflict(comparator.compare(prevKey, key) != 0, "key", prevEntry, entry);
             prevKey = key;
           }
         }
@@ -387,20 +560,20 @@ public static <K extends Comparable<?>, V> Builder<K, V> reverseOrder() {
    *         .put(1, "one")
    *         .put(2, "two")
    *         .put(3, "three")
-   *         .build();
+   *         .buildOrThrow();
    * }</pre>
    *
    * <p>For <i>small</i> immutable sorted maps, the {@code ImmutableSortedMap.of()} methods are even
    * more convenient.
    *
-   * <p>Builder instances can be reused - it is safe to call {@link #build} multiple times to build
-   * multiple maps in series. Each map is a superset of the maps created before it.
+   * <p>Builder instances can be reused - it is safe to call {@link #buildOrThrow} multiple times to
+   * build multiple maps in series. Each map is a superset of the maps created before it.
    *
    * @since 2.0
    */
   public static class Builder<K, V> extends ImmutableMap.Builder<K, V> {
-    private transient Object[] keys;
-    private transient Object[] values;
+    private transient @Nullable Object[] keys;
+    private transient @Nullable Object[] values;
     private final Comparator<? super K> comparator;
 
     /**
@@ -414,8 +587,8 @@ public Builder(Comparator<? super K> comparator) {
 
     private Builder(Comparator<? super K> comparator, int initialCapacity) {
       this.comparator = checkNotNull(comparator);
-      this.keys = new Object[initialCapacity];
-      this.values = new Object[initialCapacity];
+      this.keys = new @Nullable Object[initialCapacity];
+      this.values = new @Nullable Object[initialCapacity];
     }
 
     private void ensureCapacity(int minCapacity) {
@@ -513,16 +686,34 @@ Builder<K, V> combine(ImmutableSortedMap.Builder<K, V> other) {
     /**
      * Returns a newly-created immutable sorted map.
      *
+     * <p>Prefer the equivalent method {@link #buildOrThrow()} to make it explicit that the method
+     * will throw an exception if there are duplicate keys. The {@code build()} method will soon be
+     * deprecated.
+     *
      * @throws IllegalArgumentException if any two keys are equal according to the comparator (which
      *     might be the keys' natural order)
      */
     @Override
     public ImmutableSortedMap<K, V> build() {
+      return buildOrThrow();
+    }
+
+    /**
+     * Returns a newly-created immutable sorted map, or throws an exception if any two keys are
+     * equal.
+     *
+     * @throws IllegalArgumentException if any two keys are equal according to the comparator (which
+     *     might be the keys' natural order)
+     * @since 31.0
+     */
+    @Override
+    public ImmutableSortedMap<K, V> buildOrThrow() {
       switch (size) {
         case 0:
           return emptyMap(comparator);
         case 1:
-          return of(comparator, (K) keys[0], (V) values[0]);
+          // requireNonNull is safe because the first `size` elements have been filled in.
+          return of(comparator, (K) requireNonNull(keys[0]), (V) requireNonNull(values[0]));
         default:
           Object[] sortedKeys = Arrays.copyOf(keys, size);
           Arrays.sort((K[]) sortedKeys, comparator);
@@ -540,8 +731,10 @@ public ImmutableSortedMap<K, V> build() {
                       + " and "
                       + sortedKeys[i]);
             }
-            int index = Arrays.binarySearch((K[]) sortedKeys, (K) keys[i], comparator);
-            sortedValues[index] = values[i];
+            // requireNonNull is safe because the first `size` elements have been filled in.
+            int index =
+                Arrays.binarySearch((K[]) sortedKeys, (K) requireNonNull(keys[i]), comparator);
+            sortedValues[index] = requireNonNull(values[i]);
           }
           return new ImmutableSortedMap<K, V>(
               new RegularImmutableSortedSet<K>(
@@ -549,11 +742,29 @@ public ImmutableSortedMap<K, V> build() {
               ImmutableList.<V>asImmutableList(sortedValues));
       }
     }
+
+    /**
+     * Throws UnsupportedOperationException. A future version may support this operation. Then the
+     * value for any given key will be the one that was last supplied in a {@code put} operation for
+     * that key.
+     *
+     * @throws UnsupportedOperationException always
+     * @since 31.1
+     * @deprecated This method is not currently implemented, and may never be.
+     */
+    @DoNotCall
+    @Deprecated
+    @Override
+    public final ImmutableSortedMap<K, V> buildKeepingLast() {
+      // TODO(emcmanus): implement
+      throw new UnsupportedOperationException(
+          "ImmutableSortedMap.Builder does not yet implement buildKeepingLast()");
+    }
   }
 
   private final transient RegularImmutableSortedSet<K> keySet;
   private final transient ImmutableList<V> valueList;
-  private transient ImmutableSortedMap<K, V> descendingMap;
+  @CheckForNull private transient ImmutableSortedMap<K, V> descendingMap;
 
   ImmutableSortedMap(RegularImmutableSortedSet<K> keySet, ImmutableList<V> valueList) {
     this(keySet, valueList, null);
@@ -562,7 +773,7 @@ public ImmutableSortedMap<K, V> build() {
   ImmutableSortedMap(
       RegularImmutableSortedSet<K> keySet,
       ImmutableList<V> valueList,
-      ImmutableSortedMap<K, V> descendingMap) {
+      @CheckForNull ImmutableSortedMap<K, V> descendingMap) {
     this.keySet = keySet;
     this.valueList = valueList;
     this.descendingMap = descendingMap;
@@ -574,7 +785,8 @@ public int size() {
   }
 
   @Override
-  public V get(@NullableDecl Object key) {
+  @CheckForNull
+  public V get(@CheckForNull Object key) {
     int index = keySet.indexOf(key);
     return (index == -1) ? null : valueList.get(index);
   }
@@ -785,51 +997,61 @@ public ImmutableSortedMap<K, V> tailMap(K fromKey, boolean inclusive) {
   }
 
   @Override
+  @CheckForNull
   public Entry<K, V> lowerEntry(K key) {
     return headMap(key, false).lastEntry();
   }
 
   @Override
+  @CheckForNull
   public K lowerKey(K key) {
     return keyOrNull(lowerEntry(key));
   }
 
   @Override
+  @CheckForNull
   public Entry<K, V> floorEntry(K key) {
     return headMap(key, true).lastEntry();
   }
 
   @Override
+  @CheckForNull
   public K floorKey(K key) {
     return keyOrNull(floorEntry(key));
   }
 
   @Override
+  @CheckForNull
   public Entry<K, V> ceilingEntry(K key) {
     return tailMap(key, true).firstEntry();
   }
 
   @Override
+  @CheckForNull
   public K ceilingKey(K key) {
     return keyOrNull(ceilingEntry(key));
   }
 
   @Override
+  @CheckForNull
   public Entry<K, V> higherEntry(K key) {
     return tailMap(key, false).firstEntry();
   }
 
   @Override
+  @CheckForNull
   public K higherKey(K key) {
     return keyOrNull(higherEntry(key));
   }
 
   @Override
+  @CheckForNull
   public Entry<K, V> firstEntry() {
     return isEmpty() ? null : entrySet().asList().get(0);
   }
 
   @Override
+  @CheckForNull
   public Entry<K, V> lastEntry() {
     return isEmpty() ? null : entrySet().asList().get(size() - 1);
   }
@@ -844,6 +1066,7 @@ public Entry<K, V> lastEntry() {
   @Deprecated
   @Override
   @DoNotCall("Always throws UnsupportedOperationException")
+  @CheckForNull
   public final Entry<K, V> pollFirstEntry() {
     throw new UnsupportedOperationException();
   }
@@ -858,6 +1081,7 @@ public final Entry<K, V> pollFirstEntry() {
   @Deprecated
   @Override
   @DoNotCall("Always throws UnsupportedOperationException")
+  @CheckForNull
   public final Entry<K, V> pollLastEntry() {
     throw new UnsupportedOperationException();
   }
diff --git a/android/guava/src/com/google/common/collect/ImmutableSortedMapFauxverideShim.java b/android/guava/src/com/google/common/collect/ImmutableSortedMapFauxverideShim.java
index 1e875a3b0ca3..9b40f556f466 100644
--- a/android/guava/src/com/google/common/collect/ImmutableSortedMapFauxverideShim.java
+++ b/android/guava/src/com/google/common/collect/ImmutableSortedMapFauxverideShim.java
@@ -17,6 +17,7 @@
 package com.google.common.collect;
 
 import com.google.common.annotations.GwtIncompatible;
+import com.google.errorprone.annotations.DoNotCall;
 
 /**
  * "Overrides" the {@link ImmutableMap} static methods that lack {@link ImmutableSortedMap}
@@ -26,6 +27,7 @@
  * @author Chris Povirk
  */
 @GwtIncompatible
+@ElementTypesAreNonnullByDefault
 abstract class ImmutableSortedMapFauxverideShim<K, V> extends ImmutableMap<K, V> {
   /**
    * Not supported. Use {@link ImmutableSortedMap#naturalOrder}, which offers better type-safety,
@@ -35,6 +37,7 @@ abstract class ImmutableSortedMapFauxverideShim<K, V> extends ImmutableMap<K, V>
    * @throws UnsupportedOperationException always
    * @deprecated Use {@link ImmutableSortedMap#naturalOrder}, which offers better type-safety.
    */
+  @DoNotCall("Use naturalOrder")
   @Deprecated
   public static <K, V> ImmutableSortedMap.Builder<K, V> builder() {
     throw new UnsupportedOperationException();
@@ -46,6 +49,7 @@ public static <K, V> ImmutableSortedMap.Builder<K, V> builder() {
    * @throws UnsupportedOperationException always
    * @deprecated Not supported for ImmutableSortedMap.
    */
+  @DoNotCall("Use naturalOrder (which does not accept an expected size)")
   @Deprecated
   public static <K, V> ImmutableSortedMap.Builder<K, V> builderWithExpectedSize(int expectedSize) {
     throw new UnsupportedOperationException();
@@ -60,6 +64,7 @@ public static <K, V> ImmutableSortedMap.Builder<K, V> builderWithExpectedSize(in
    * @deprecated <b>Pass a key of type {@code Comparable} to use {@link
    *     ImmutableSortedMap#of(Comparable, Object)}.</b>
    */
+  @DoNotCall("Pass a key of type Comparable")
   @Deprecated
   public static <K, V> ImmutableSortedMap<K, V> of(K k1, V v1) {
     throw new UnsupportedOperationException();
@@ -74,6 +79,7 @@ public static <K, V> ImmutableSortedMap<K, V> of(K k1, V v1) {
    * @deprecated <b>Pass keys of type {@code Comparable} to use {@link
    *     ImmutableSortedMap#of(Comparable, Object, Comparable, Object)}.</b>
    */
+  @DoNotCall("Pass keys of type Comparable")
   @Deprecated
   public static <K, V> ImmutableSortedMap<K, V> of(K k1, V v1, K k2, V v2) {
     throw new UnsupportedOperationException();
@@ -88,6 +94,7 @@ public static <K, V> ImmutableSortedMap<K, V> of(K k1, V v1, K k2, V v2) {
    * @deprecated <b>Pass keys of type {@code Comparable} to use {@link
    *     ImmutableSortedMap#of(Comparable, Object, Comparable, Object, Comparable, Object)}.</b>
    */
+  @DoNotCall("Pass keys of type Comparable")
   @Deprecated
   public static <K, V> ImmutableSortedMap<K, V> of(K k1, V v1, K k2, V v2, K k3, V v3) {
     throw new UnsupportedOperationException();
@@ -103,6 +110,7 @@ public static <K, V> ImmutableSortedMap<K, V> of(K k1, V v1, K k2, V v2, K k3, V
    *     ImmutableSortedMap#of(Comparable, Object, Comparable, Object, Comparable, Object,
    *     Comparable, Object)}.</b>
    */
+  @DoNotCall("Pass keys of type Comparable")
   @Deprecated
   public static <K, V> ImmutableSortedMap<K, V> of(K k1, V v1, K k2, V v2, K k3, V v3, K k4, V v4) {
     throw new UnsupportedOperationException();
@@ -118,11 +126,160 @@ public static <K, V> ImmutableSortedMap<K, V> of(K k1, V v1, K k2, V v2, K k3, V
    *     ImmutableSortedMap#of(Comparable, Object, Comparable, Object, Comparable, Object,
    *     Comparable, Object, Comparable, Object)}.</b>
    */
+  @DoNotCall("Pass keys of type Comparable")
   @Deprecated
   public static <K, V> ImmutableSortedMap<K, V> of(
       K k1, V v1, K k2, V v2, K k3, V v3, K k4, V v4, K k5, V v5) {
     throw new UnsupportedOperationException();
   }
 
+  /**
+   * Not supported. <b>You are attempting to create a map that may contain non-{@code Comparable}
+   * keys.</b> Proper calls will resolve to the version in {@code ImmutableSortedMap}, not this
+   * dummy version.
+   *
+   * @throws UnsupportedOperationException always
+   * @deprecated <b>Pass keys of type {@code Comparable} to use {@link
+   *     ImmutableSortedMap#of(Comparable, Object, Comparable, Object, Comparable, Object,
+   *     Comparable, Object, Comparable, Object)}.</b>
+   */
+  @DoNotCall("Pass keys of type Comparable")
+  @Deprecated
+  public static <K, V> ImmutableSortedMap<K, V> of(
+      K k1, V v1, K k2, V v2, K k3, V v3, K k4, V v4, K k5, V v5, K k6, V v6) {
+    throw new UnsupportedOperationException();
+  }
+
+  /**
+   * Not supported. <b>You are attempting to create a map that may contain non-{@code Comparable}
+   * keys.</b> Proper calls will resolve to the version in {@code ImmutableSortedMap}, not this
+   * dummy version.
+   *
+   * @throws UnsupportedOperationException always
+   * @deprecated <b>Pass keys of type {@code Comparable} to use {@link
+   *     ImmutableSortedMap#of(Comparable, Object, Comparable, Object, Comparable, Object,
+   *     Comparable, Object, Comparable, Object)}.</b>
+   */
+  @DoNotCall("Pass keys of type Comparable")
+  @Deprecated
+  public static <K, V> ImmutableSortedMap<K, V> of(
+      K k1, V v1, K k2, V v2, K k3, V v3, K k4, V v4, K k5, V v5, K k6, V v6, K k7, V v7) {
+    throw new UnsupportedOperationException();
+  }
+
+  /**
+   * Not supported. <b>You are attempting to create a map that may contain non-{@code Comparable}
+   * keys.</b> Proper calls will resolve to the version in {@code ImmutableSortedMap}, not this
+   * dummy version.
+   *
+   * @throws UnsupportedOperationException always
+   * @deprecated <b>Pass keys of type {@code Comparable} to use {@link
+   *     ImmutableSortedMap#of(Comparable, Object, Comparable, Object, Comparable, Object,
+   *     Comparable, Object, Comparable, Object)}.</b>
+   */
+  @DoNotCall("Pass keys of type Comparable")
+  @Deprecated
+  public static <K, V> ImmutableSortedMap<K, V> of(
+      K k1,
+      V v1,
+      K k2,
+      V v2,
+      K k3,
+      V v3,
+      K k4,
+      V v4,
+      K k5,
+      V v5,
+      K k6,
+      V v6,
+      K k7,
+      V v7,
+      K k8,
+      V v8) {
+    throw new UnsupportedOperationException();
+  }
+
+  /**
+   * Not supported. <b>You are attempting to create a map that may contain non-{@code Comparable}
+   * keys.</b> Proper calls will resolve to the version in {@code ImmutableSortedMap}, not this
+   * dummy version.
+   *
+   * @throws UnsupportedOperationException always
+   * @deprecated <b>Pass keys of type {@code Comparable} to use {@link
+   *     ImmutableSortedMap#of(Comparable, Object, Comparable, Object, Comparable, Object,
+   *     Comparable, Object, Comparable, Object)}.</b>
+   */
+  @DoNotCall("Pass keys of type Comparable")
+  @Deprecated
+  public static <K, V> ImmutableSortedMap<K, V> of(
+      K k1,
+      V v1,
+      K k2,
+      V v2,
+      K k3,
+      V v3,
+      K k4,
+      V v4,
+      K k5,
+      V v5,
+      K k6,
+      V v6,
+      K k7,
+      V v7,
+      K k8,
+      V v8,
+      K k9,
+      V v9) {
+    throw new UnsupportedOperationException();
+  }
+
+  /**
+   * Not supported. <b>You are attempting to create a map that may contain non-{@code Comparable}
+   * keys.</b> Proper calls will resolve to the version in {@code ImmutableSortedMap}, not this
+   * dummy version.
+   *
+   * @throws UnsupportedOperationException always
+   * @deprecated <b>Pass keys of type {@code Comparable} to use {@link
+   *     ImmutableSortedMap#of(Comparable, Object, Comparable, Object, Comparable, Object,
+   *     Comparable, Object, Comparable, Object)}.</b>
+   */
+  @DoNotCall("Pass keys of type Comparable")
+  @Deprecated
+  public static <K, V> ImmutableSortedMap<K, V> of(
+      K k1,
+      V v1,
+      K k2,
+      V v2,
+      K k3,
+      V v3,
+      K k4,
+      V v4,
+      K k5,
+      V v5,
+      K k6,
+      V v6,
+      K k7,
+      V v7,
+      K k8,
+      V v8,
+      K k9,
+      V v9,
+      K k10,
+      V v10) {
+    throw new UnsupportedOperationException();
+  }
+
+  /**
+   * Not supported. Use {@code ImmutableSortedMap.copyOf(ImmutableMap.ofEntries(...))}.
+   *
+   * @deprecated Use {@code ImmutableSortedMap.copyOf(ImmutableMap.ofEntries(...))}.
+   */
+  @DoNotCall("ImmutableSortedMap.ofEntries not currently available; use ImmutableSortedMap.copyOf")
+  @Deprecated
+  public static <K, V> ImmutableSortedMap<K, V> ofEntries(
+      Entry<? extends K, ? extends V>... entries) {
+    throw new UnsupportedOperationException();
+  }
+
   // No copyOf() fauxveride; see ImmutableSortedSetFauxverideShim.
 }
diff --git a/android/guava/src/com/google/common/collect/ImmutableSortedMultiset.java b/android/guava/src/com/google/common/collect/ImmutableSortedMultiset.java
index ca3e306cd4b1..2889a50ccfb6 100644
--- a/android/guava/src/com/google/common/collect/ImmutableSortedMultiset.java
+++ b/android/guava/src/com/google/common/collect/ImmutableSortedMultiset.java
@@ -30,6 +30,7 @@
 import java.util.Comparator;
 import java.util.Iterator;
 import java.util.List;
+import javax.annotation.CheckForNull;
 
 /**
  * A {@link SortedMultiset} whose contents will never change, with many other important properties
@@ -42,17 +43,22 @@
  * collection will not correctly obey its specification.
  *
  * <p>See the Guava User Guide article on <a href=
- * "https://github.com/google/guava/wiki/ImmutableCollectionsExplained"> immutable collections</a>.
+ * "https://github.com/google/guava/wiki/ImmutableCollectionsExplained">immutable collections</a>.
  *
  * @author Louis Wasserman
  * @since 12.0
  */
 @GwtIncompatible // hasn't been tested yet
+@ElementTypesAreNonnullByDefault
 public abstract class ImmutableSortedMultiset<E> extends ImmutableSortedMultisetFauxverideShim<E>
     implements SortedMultiset<E> {
   // TODO(lowasser): GWT compatibility
 
-  /** Returns the empty immutable sorted multiset. */
+  /**
+   * Returns the empty immutable sorted multiset.
+   *
+   * <p><b>Performance note:</b> the instance returned is a singleton.
+   */
   @SuppressWarnings("unchecked")
   public static <E> ImmutableSortedMultiset<E> of() {
     return (ImmutableSortedMultiset) RegularImmutableSortedMultiset.NATURAL_EMPTY_MULTISET;
@@ -72,7 +78,6 @@ public static <E extends Comparable<? super E>> ImmutableSortedMultiset<E> of(E
    *
    * @throws NullPointerException if any element is null
    */
-  @SuppressWarnings("unchecked")
   public static <E extends Comparable<? super E>> ImmutableSortedMultiset<E> of(E e1, E e2) {
     return copyOf(Ordering.natural(), Arrays.asList(e1, e2));
   }
@@ -83,7 +88,6 @@ public static <E extends Comparable<? super E>> ImmutableSortedMultiset<E> of(E
    *
    * @throws NullPointerException if any element is null
    */
-  @SuppressWarnings("unchecked")
   public static <E extends Comparable<? super E>> ImmutableSortedMultiset<E> of(E e1, E e2, E e3) {
     return copyOf(Ordering.natural(), Arrays.asList(e1, e2, e3));
   }
@@ -94,7 +98,6 @@ public static <E extends Comparable<? super E>> ImmutableSortedMultiset<E> of(E
    *
    * @throws NullPointerException if any element is null
    */
-  @SuppressWarnings("unchecked")
   public static <E extends Comparable<? super E>> ImmutableSortedMultiset<E> of(
       E e1, E e2, E e3, E e4) {
     return copyOf(Ordering.natural(), Arrays.asList(e1, e2, e3, e4));
@@ -106,7 +109,6 @@ public static <E extends Comparable<? super E>> ImmutableSortedMultiset<E> of(
    *
    * @throws NullPointerException if any element is null
    */
-  @SuppressWarnings("unchecked")
   public static <E extends Comparable<? super E>> ImmutableSortedMultiset<E> of(
       E e1, E e2, E e3, E e4, E e5) {
     return copyOf(Ordering.natural(), Arrays.asList(e1, e2, e3, e4, e5));
@@ -118,7 +120,6 @@ public static <E extends Comparable<? super E>> ImmutableSortedMultiset<E> of(
    *
    * @throws NullPointerException if any element is null
    */
-  @SuppressWarnings("unchecked")
   public static <E extends Comparable<? super E>> ImmutableSortedMultiset<E> of(
       E e1, E e2, E e3, E e4, E e5, E e6, E... remaining) {
     int size = remaining.length + 6;
@@ -282,7 +283,7 @@ public final Comparator<? super E> comparator() {
   @Override
   public abstract ImmutableSortedSet<E> elementSet();
 
-  @LazyInit transient ImmutableSortedMultiset<E> descendingMultiset;
+  @LazyInit @CheckForNull transient ImmutableSortedMultiset<E> descendingMultiset;
 
   @Override
   public ImmutableSortedMultiset<E> descendingMultiset() {
@@ -308,6 +309,7 @@ public ImmutableSortedMultiset<E> descendingMultiset() {
   @Deprecated
   @Override
   @DoNotCall("Always throws UnsupportedOperationException")
+  @CheckForNull
   public final Entry<E> pollFirstEntry() {
     throw new UnsupportedOperationException();
   }
@@ -324,6 +326,7 @@ public final Entry<E> pollFirstEntry() {
   @Deprecated
   @Override
   @DoNotCall("Always throws UnsupportedOperationException")
+  @CheckForNull
   public final Entry<E> pollLastEntry() {
     throw new UnsupportedOperationException();
   }
diff --git a/android/guava/src/com/google/common/collect/ImmutableSortedMultisetFauxverideShim.java b/android/guava/src/com/google/common/collect/ImmutableSortedMultisetFauxverideShim.java
index 39d41ed26c5c..c8a7ed782fc4 100644
--- a/android/guava/src/com/google/common/collect/ImmutableSortedMultisetFauxverideShim.java
+++ b/android/guava/src/com/google/common/collect/ImmutableSortedMultisetFauxverideShim.java
@@ -15,6 +15,7 @@
 package com.google.common.collect;
 
 import com.google.common.annotations.GwtIncompatible;
+import com.google.errorprone.annotations.DoNotCall;
 
 /**
  * "Overrides" the {@link ImmutableMultiset} static methods that lack {@link
@@ -34,6 +35,7 @@
  * @author Louis Wasserman
  */
 @GwtIncompatible
+@ElementTypesAreNonnullByDefault
 abstract class ImmutableSortedMultisetFauxverideShim<E> extends ImmutableMultiset<E> {
   /**
    * Not supported. Use {@link ImmutableSortedMultiset#naturalOrder}, which offers better
@@ -43,6 +45,7 @@ abstract class ImmutableSortedMultisetFauxverideShim<E> extends ImmutableMultise
    * @throws UnsupportedOperationException always
    * @deprecated Use {@link ImmutableSortedMultiset#naturalOrder}, which offers better type-safety.
    */
+  @DoNotCall("Use naturalOrder.")
   @Deprecated
   public static <E> ImmutableSortedMultiset.Builder<E> builder() {
     throw new UnsupportedOperationException();
@@ -57,6 +60,7 @@ public static <E> ImmutableSortedMultiset.Builder<E> builder() {
    * @deprecated <b>Pass a parameter of type {@code Comparable} to use {@link
    *     ImmutableSortedMultiset#of(Comparable)}.</b>
    */
+  @DoNotCall("Elements must be Comparable. (Or, pass a Comparator to orderedBy or copyOf.)")
   @Deprecated
   public static <E> ImmutableSortedMultiset<E> of(E element) {
     throw new UnsupportedOperationException();
@@ -71,6 +75,7 @@ public static <E> ImmutableSortedMultiset<E> of(E element) {
    * @deprecated <b>Pass the parameters of type {@code Comparable} to use {@link
    *     ImmutableSortedMultiset#of(Comparable, Comparable)}.</b>
    */
+  @DoNotCall("Elements must be Comparable. (Or, pass a Comparator to orderedBy or copyOf.)")
   @Deprecated
   public static <E> ImmutableSortedMultiset<E> of(E e1, E e2) {
     throw new UnsupportedOperationException();
@@ -85,6 +90,7 @@ public static <E> ImmutableSortedMultiset<E> of(E e1, E e2) {
    * @deprecated <b>Pass the parameters of type {@code Comparable} to use {@link
    *     ImmutableSortedMultiset#of(Comparable, Comparable, Comparable)}.</b>
    */
+  @DoNotCall("Elements must be Comparable. (Or, pass a Comparator to orderedBy or copyOf.)")
   @Deprecated
   public static <E> ImmutableSortedMultiset<E> of(E e1, E e2, E e3) {
     throw new UnsupportedOperationException();
@@ -99,6 +105,7 @@ public static <E> ImmutableSortedMultiset<E> of(E e1, E e2, E e3) {
    * @deprecated <b>Pass the parameters of type {@code Comparable} to use {@link
    *     ImmutableSortedMultiset#of(Comparable, Comparable, Comparable, Comparable)}. </b>
    */
+  @DoNotCall("Elements must be Comparable. (Or, pass a Comparator to orderedBy or copyOf.)")
   @Deprecated
   public static <E> ImmutableSortedMultiset<E> of(E e1, E e2, E e3, E e4) {
     throw new UnsupportedOperationException();
@@ -114,6 +121,7 @@ public static <E> ImmutableSortedMultiset<E> of(E e1, E e2, E e3, E e4) {
    *     ImmutableSortedMultiset#of(Comparable, Comparable, Comparable, Comparable, Comparable)} .
    *     </b>
    */
+  @DoNotCall("Elements must be Comparable. (Or, pass a Comparator to orderedBy or copyOf.)")
   @Deprecated
   public static <E> ImmutableSortedMultiset<E> of(E e1, E e2, E e3, E e4, E e5) {
     throw new UnsupportedOperationException();
@@ -129,6 +137,7 @@ public static <E> ImmutableSortedMultiset<E> of(E e1, E e2, E e3, E e4, E e5) {
    *     ImmutableSortedMultiset#of(Comparable, Comparable, Comparable, Comparable, Comparable,
    *     Comparable, Comparable...)} . </b>
    */
+  @DoNotCall("Elements must be Comparable. (Or, pass a Comparator to orderedBy or copyOf.)")
   @Deprecated
   public static <E> ImmutableSortedMultiset<E> of(
       E e1, E e2, E e3, E e4, E e5, E e6, E... remaining) {
@@ -144,6 +153,7 @@ public static <E> ImmutableSortedMultiset<E> of(
    * @deprecated <b>Pass parameters of type {@code Comparable} to use {@link
    *     ImmutableSortedMultiset#copyOf(Comparable[])}.</b>
    */
+  @DoNotCall("Elements must be Comparable. (Or, pass a Comparator to orderedBy or copyOf.)")
   @Deprecated
   public static <E> ImmutableSortedMultiset<E> copyOf(E[] elements) {
     throw new UnsupportedOperationException();
diff --git a/android/guava/src/com/google/common/collect/ImmutableSortedSet.java b/android/guava/src/com/google/common/collect/ImmutableSortedSet.java
index ee5038930d7b..a21227debb1b 100644
--- a/android/guava/src/com/google/common/collect/ImmutableSortedSet.java
+++ b/android/guava/src/com/google/common/collect/ImmutableSortedSet.java
@@ -35,7 +35,8 @@
 import java.util.Iterator;
 import java.util.NavigableSet;
 import java.util.SortedSet;
-import org.checkerframework.checker.nullness.compatqual.NullableDecl;
+import javax.annotation.CheckForNull;
+import org.checkerframework.checker.nullness.qual.Nullable;
 
 /**
  * A {@link NavigableSet} whose contents will never change, with many other important properties
@@ -48,7 +49,7 @@
  * collection will not correctly obey its specification.
  *
  * <p>See the Guava User Guide article on <a href=
- * "https://github.com/google/guava/wiki/ImmutableCollectionsExplained"> immutable collections</a>.
+ * "https://github.com/google/guava/wiki/ImmutableCollectionsExplained">immutable collections</a>.
  *
  * @author Jared Levy
  * @author Louis Wasserman
@@ -57,6 +58,7 @@
 // TODO(benyu): benchmark and optimize all creation paths, which are a mess now
 @GwtCompatible(serializable = true, emulated = true)
 @SuppressWarnings("serial") // we're overriding default serialization
+@ElementTypesAreNonnullByDefault
 public abstract class ImmutableSortedSet<E> extends ImmutableSortedSetFauxverideShim<E>
     implements NavigableSet<E>, SortedIterable<E> {
   static <E> RegularImmutableSortedSet<E> emptySet(Comparator<? super E> comparator) {
@@ -67,7 +69,11 @@ static <E> RegularImmutableSortedSet<E> emptySet(Comparator<? super E> comparato
     }
   }
 
-  /** Returns the empty immutable sorted set. */
+  /**
+   * Returns the empty immutable sorted set.
+   *
+   * <p><b>Performance note:</b> the instance returned is a singleton.
+   */
   public static <E> ImmutableSortedSet<E> of() {
     return (ImmutableSortedSet<E>) RegularImmutableSortedSet.NATURAL_EMPTY_SET;
   }
@@ -503,16 +509,16 @@ public ImmutableSortedSet<E> build() {
     }
   }
 
-  int unsafeCompare(Object a, Object b) {
+  int unsafeCompare(Object a, @CheckForNull Object b) {
     return unsafeCompare(comparator, a, b);
   }
 
-  static int unsafeCompare(Comparator<?> comparator, Object a, Object b) {
+  static int unsafeCompare(Comparator<?> comparator, Object a, @CheckForNull Object b) {
     // Pretend the comparator can compare anything. If it turns out it can't
-    // compare a and b, we should get a CCE on the subsequent line. Only methods
-    // that are spec'd to throw CCE should call this.
-    @SuppressWarnings("unchecked")
-    Comparator<Object> unsafeComparator = (Comparator<Object>) comparator;
+    // compare a and b, we should get a CCE or NPE on the subsequent line. Only methods
+    // that are spec'd to throw CCE and NPE should call this.
+    @SuppressWarnings({"unchecked", "nullness"})
+    Comparator<@Nullable Object> unsafeComparator = (Comparator<@Nullable Object>) comparator;
     return unsafeComparator.compare(a, b);
   }
 
@@ -619,18 +625,21 @@ abstract ImmutableSortedSet<E> subSetImpl(
   /** @since 12.0 */
   @GwtIncompatible // NavigableSet
   @Override
+  @CheckForNull
   public E lower(E e) {
     return Iterators.getNext(headSet(e, false).descendingIterator(), null);
   }
 
   /** @since 12.0 */
   @Override
+  @CheckForNull
   public E floor(E e) {
     return Iterators.getNext(headSet(e, true).descendingIterator(), null);
   }
 
   /** @since 12.0 */
   @Override
+  @CheckForNull
   public E ceiling(E e) {
     return Iterables.getFirst(tailSet(e, true), null);
   }
@@ -638,6 +647,7 @@ public E ceiling(E e) {
   /** @since 12.0 */
   @GwtIncompatible // NavigableSet
   @Override
+  @CheckForNull
   public E higher(E e) {
     return Iterables.getFirst(tailSet(e, false), null);
   }
@@ -664,6 +674,7 @@ public E last() {
   @GwtIncompatible // NavigableSet
   @Override
   @DoNotCall("Always throws UnsupportedOperationException")
+  @CheckForNull
   public final E pollFirst() {
     throw new UnsupportedOperationException();
   }
@@ -680,12 +691,14 @@ public final E pollFirst() {
   @GwtIncompatible // NavigableSet
   @Override
   @DoNotCall("Always throws UnsupportedOperationException")
+  @CheckForNull
   public final E pollLast() {
     throw new UnsupportedOperationException();
   }
 
   @GwtIncompatible // NavigableSet
   @LazyInit
+  @CheckForNull
   transient ImmutableSortedSet<E> descendingSet;
 
   /** @since 12.0 */
@@ -713,7 +726,7 @@ public ImmutableSortedSet<E> descendingSet() {
   public abstract UnmodifiableIterator<E> descendingIterator();
 
   /** Returns the position of an element within the set, or -1 if not present. */
-  abstract int indexOf(@NullableDecl Object target);
+  abstract int indexOf(@CheckForNull Object target);
 
   /*
    * This class is used to serialize all ImmutableSortedSet instances,
diff --git a/android/guava/src/com/google/common/collect/ImmutableSortedSetFauxverideShim.java b/android/guava/src/com/google/common/collect/ImmutableSortedSetFauxverideShim.java
index 9d2af2c18106..ca19d79db194 100644
--- a/android/guava/src/com/google/common/collect/ImmutableSortedSetFauxverideShim.java
+++ b/android/guava/src/com/google/common/collect/ImmutableSortedSetFauxverideShim.java
@@ -17,6 +17,7 @@
 package com.google.common.collect;
 
 import com.google.common.annotations.GwtIncompatible;
+import com.google.errorprone.annotations.DoNotCall;
 
 /**
  * "Overrides" the {@link ImmutableSet} static methods that lack {@link ImmutableSortedSet}
@@ -36,6 +37,7 @@
  * @author Chris Povirk
  */
 @GwtIncompatible
+@ElementTypesAreNonnullByDefault
 abstract class ImmutableSortedSetFauxverideShim<E> extends ImmutableSet<E> {
   /**
    * Not supported. Use {@link ImmutableSortedSet#naturalOrder}, which offers better type-safety,
@@ -45,6 +47,7 @@ abstract class ImmutableSortedSetFauxverideShim<E> extends ImmutableSet<E> {
    * @throws UnsupportedOperationException always
    * @deprecated Use {@link ImmutableSortedSet#naturalOrder}, which offers better type-safety.
    */
+  @DoNotCall("Use naturalOrder")
   @Deprecated
   public static <E> ImmutableSortedSet.Builder<E> builder() {
     throw new UnsupportedOperationException();
@@ -57,6 +60,7 @@ public static <E> ImmutableSortedSet.Builder<E> builder() {
    * @throws UnsupportedOperationException always
    * @deprecated Not supported by ImmutableSortedSet.
    */
+  @DoNotCall("Use naturalOrder (which does not accept an expected size)")
   @Deprecated
   public static <E> ImmutableSortedSet.Builder<E> builderWithExpectedSize(int expectedSize) {
     throw new UnsupportedOperationException();
@@ -71,6 +75,7 @@ public static <E> ImmutableSortedSet.Builder<E> builderWithExpectedSize(int expe
    * @deprecated <b>Pass a parameter of type {@code Comparable} to use {@link
    *     ImmutableSortedSet#of(Comparable)}.</b>
    */
+  @DoNotCall("Pass a parameter of type Comparable")
   @Deprecated
   public static <E> ImmutableSortedSet<E> of(E element) {
     throw new UnsupportedOperationException();
@@ -85,6 +90,7 @@ public static <E> ImmutableSortedSet<E> of(E element) {
    * @deprecated <b>Pass the parameters of type {@code Comparable} to use {@link
    *     ImmutableSortedSet#of(Comparable, Comparable)}.</b>
    */
+  @DoNotCall("Pass parameters of type Comparable")
   @Deprecated
   public static <E> ImmutableSortedSet<E> of(E e1, E e2) {
     throw new UnsupportedOperationException();
@@ -99,6 +105,7 @@ public static <E> ImmutableSortedSet<E> of(E e1, E e2) {
    * @deprecated <b>Pass the parameters of type {@code Comparable} to use {@link
    *     ImmutableSortedSet#of(Comparable, Comparable, Comparable)}.</b>
    */
+  @DoNotCall("Pass parameters of type Comparable")
   @Deprecated
   public static <E> ImmutableSortedSet<E> of(E e1, E e2, E e3) {
     throw new UnsupportedOperationException();
@@ -113,6 +120,7 @@ public static <E> ImmutableSortedSet<E> of(E e1, E e2, E e3) {
    * @deprecated <b>Pass the parameters of type {@code Comparable} to use {@link
    *     ImmutableSortedSet#of(Comparable, Comparable, Comparable, Comparable)}. </b>
    */
+  @DoNotCall("Pass parameters of type Comparable")
   @Deprecated
   public static <E> ImmutableSortedSet<E> of(E e1, E e2, E e3, E e4) {
     throw new UnsupportedOperationException();
@@ -127,6 +135,7 @@ public static <E> ImmutableSortedSet<E> of(E e1, E e2, E e3, E e4) {
    * @deprecated <b>Pass the parameters of type {@code Comparable} to use {@link
    *     ImmutableSortedSet#of( Comparable, Comparable, Comparable, Comparable, Comparable)}. </b>
    */
+  @DoNotCall("Pass parameters of type Comparable")
   @Deprecated
   public static <E> ImmutableSortedSet<E> of(E e1, E e2, E e3, E e4, E e5) {
     throw new UnsupportedOperationException();
@@ -142,6 +151,7 @@ public static <E> ImmutableSortedSet<E> of(E e1, E e2, E e3, E e4, E e5) {
    *     ImmutableSortedSet#of(Comparable, Comparable, Comparable, Comparable, Comparable,
    *     Comparable, Comparable...)}. </b>
    */
+  @DoNotCall("Pass parameters of type Comparable")
   @Deprecated
   public static <E> ImmutableSortedSet<E> of(E e1, E e2, E e3, E e4, E e5, E e6, E... remaining) {
     throw new UnsupportedOperationException();
@@ -156,6 +166,7 @@ public static <E> ImmutableSortedSet<E> of(E e1, E e2, E e3, E e4, E e5, E e6, E
    * @deprecated <b>Pass parameters of type {@code Comparable} to use {@link
    *     ImmutableSortedSet#copyOf(Comparable[])}.</b>
    */
+  @DoNotCall("Pass parameters of type Comparable")
   @Deprecated
   public static <E> ImmutableSortedSet<E> copyOf(E[] elements) {
     throw new UnsupportedOperationException();
diff --git a/android/guava/src/com/google/common/collect/ImmutableTable.java b/android/guava/src/com/google/common/collect/ImmutableTable.java
index 47030762cf8a..224df09c5b30 100644
--- a/android/guava/src/com/google/common/collect/ImmutableTable.java
+++ b/android/guava/src/com/google/common/collect/ImmutableTable.java
@@ -28,22 +28,28 @@
 import java.util.Iterator;
 import java.util.List;
 import java.util.Map;
-import org.checkerframework.checker.nullness.compatqual.NullableDecl;
+import javax.annotation.CheckForNull;
 
 /**
  * A {@link Table} whose contents will never change, with many other important properties detailed
  * at {@link ImmutableCollection}.
  *
  * <p>See the Guava User Guide article on <a href=
- * "https://github.com/google/guava/wiki/ImmutableCollectionsExplained"> immutable collections</a>.
+ * "https://github.com/google/guava/wiki/ImmutableCollectionsExplained">immutable collections</a>.
  *
  * @author Gregory Kick
  * @since 11.0
  */
 @GwtCompatible
+@ElementTypesAreNonnullByDefault
 public abstract class ImmutableTable<R, C, V> extends AbstractTable<R, C, V>
     implements Serializable {
-  /** Returns an empty immutable table. */
+
+  /**
+   * Returns an empty immutable table.
+   *
+   * <p><b>Performance note:</b> the instance returned is a singleton.
+   */
   @SuppressWarnings("unchecked")
   public static <R, C, V> ImmutableTable<R, C, V> of() {
     return (ImmutableTable<R, C, V>) SparseImmutableTable.EMPTY;
@@ -116,7 +122,7 @@ static <R, C, V> Cell<R, C, V> cellOf(R rowKey, C columnKey, V value) {
    *         .put(1, 'A', "foo")
    *         .put(1, 'B', "bar")
    *         .put(2, 'A', "baz")
-   *         .build();
+   *         .buildOrThrow();
    * }</pre>
    *
    * <p>By default, the order in which cells are added to the builder determines the iteration
@@ -127,16 +133,16 @@ static <R, C, V> Cell<R, C, V> cellOf(R rowKey, C columnKey, V value) {
    * <p>For empty or single-cell immutable tables, {@link #of()} and {@link #of(Object, Object,
    * Object)} are even more convenient.
    *
-   * <p>Builder instances can be reused - it is safe to call {@link #build} multiple times to build
-   * multiple tables in series. Each table is a superset of the tables created before it.
+   * <p>Builder instances can be reused - it is safe to call {@link #buildOrThrow} multiple times to
+   * build multiple tables in series. Each table is a superset of the tables created before it.
    *
    * @since 11.0
    */
   @DoNotMock
   public static final class Builder<R, C, V> {
     private final List<Cell<R, C, V>> cells = Lists.newArrayList();
-    @NullableDecl private Comparator<? super R> rowComparator;
-    @NullableDecl private Comparator<? super C> columnComparator;
+    @CheckForNull private Comparator<? super R> rowComparator;
+    @CheckForNull private Comparator<? super C> columnComparator;
 
     /**
      * Creates a new builder. The returned builder is equivalent to the builder generated by {@link
@@ -210,9 +216,24 @@ Builder<R, C, V> combine(Builder<R, C, V> other) {
     /**
      * Returns a newly-created immutable table.
      *
+     * <p>Prefer the equivalent method {@link #buildOrThrow()} to make it explicit that the method
+     * will throw an exception if there are duplicate key pairs. The {@code build()} method will
+     * soon be deprecated.
+     *
      * @throws IllegalArgumentException if duplicate key pairs were added
      */
     public ImmutableTable<R, C, V> build() {
+      return buildOrThrow();
+    }
+
+    /**
+     * Returns a newly-created immutable table, or throws an exception if duplicate key pairs were
+     * added.
+     *
+     * @throws IllegalArgumentException if duplicate key pairs were added
+     * @since 31.0
+     */
+    public ImmutableTable<R, C, V> buildOrThrow() {
       int size = cells.size();
       switch (size) {
         case 0:
@@ -306,12 +327,12 @@ public ImmutableSet<R> rowKeySet() {
   public abstract ImmutableMap<R, Map<C, V>> rowMap();
 
   @Override
-  public boolean contains(@NullableDecl Object rowKey, @NullableDecl Object columnKey) {
+  public boolean contains(@CheckForNull Object rowKey, @CheckForNull Object columnKey) {
     return get(rowKey, columnKey) != null;
   }
 
   @Override
-  public boolean containsValue(@NullableDecl Object value) {
+  public boolean containsValue(@CheckForNull Object value) {
     return values().contains(value);
   }
 
@@ -338,6 +359,7 @@ public final void clear() {
   @Deprecated
   @Override
   @DoNotCall("Always throws UnsupportedOperationException")
+  @CheckForNull
   public final V put(R rowKey, C columnKey, V value) {
     throw new UnsupportedOperationException();
   }
@@ -365,7 +387,8 @@ public final void putAll(Table<? extends R, ? extends C, ? extends V> table) {
   @Deprecated
   @Override
   @DoNotCall("Always throws UnsupportedOperationException")
-  public final V remove(Object rowKey, Object columnKey) {
+  @CheckForNull
+  public final V remove(@CheckForNull Object rowKey, @CheckForNull Object columnKey) {
     throw new UnsupportedOperationException();
   }
 
diff --git a/android/guava/src/com/google/common/collect/IndexedImmutableSet.java b/android/guava/src/com/google/common/collect/IndexedImmutableSet.java
index a31d3b28648d..25aae94e8b96 100644
--- a/android/guava/src/com/google/common/collect/IndexedImmutableSet.java
+++ b/android/guava/src/com/google/common/collect/IndexedImmutableSet.java
@@ -18,8 +18,10 @@
 
 import com.google.common.annotations.GwtCompatible;
 import com.google.common.annotations.GwtIncompatible;
+import org.checkerframework.checker.nullness.qual.Nullable;
 
 @GwtCompatible(emulated = true)
+@ElementTypesAreNonnullByDefault
 abstract class IndexedImmutableSet<E> extends ImmutableSet<E> {
   abstract E get(int index);
 
@@ -30,7 +32,7 @@ public UnmodifiableIterator<E> iterator() {
 
   @Override
   @GwtIncompatible
-  int copyIntoArray(Object[] dst, int offset) {
+  int copyIntoArray(@Nullable Object[] dst, int offset) {
     return asList().copyIntoArray(dst, offset);
   }
 
diff --git a/android/guava/src/com/google/common/collect/Interner.java b/android/guava/src/com/google/common/collect/Interner.java
index 310bfca6f0b3..bfc2035f101b 100644
--- a/android/guava/src/com/google/common/collect/Interner.java
+++ b/android/guava/src/com/google/common/collect/Interner.java
@@ -16,7 +16,6 @@
 
 package com.google.common.collect;
 
-import com.google.common.annotations.Beta;
 import com.google.common.annotations.GwtIncompatible;
 import com.google.errorprone.annotations.CanIgnoreReturnValue;
 import com.google.errorprone.annotations.DoNotMock;
@@ -32,9 +31,9 @@
  * @author Kevin Bourrillion
  * @since 3.0
  */
-@Beta
 @DoNotMock("Use Interners.new*Interner")
 @GwtIncompatible
+@ElementTypesAreNonnullByDefault
 public interface Interner<E> {
   /**
    * Chooses and returns the representative instance for any of a collection of instances that are
diff --git a/android/guava/src/com/google/common/collect/Interners.java b/android/guava/src/com/google/common/collect/Interners.java
index 061a1cfc7c73..10ae2746332b 100644
--- a/android/guava/src/com/google/common/collect/Interners.java
+++ b/android/guava/src/com/google/common/collect/Interners.java
@@ -16,13 +16,13 @@
 
 import static com.google.common.base.Preconditions.checkNotNull;
 
-import com.google.common.annotations.Beta;
 import com.google.common.annotations.GwtIncompatible;
 import com.google.common.annotations.VisibleForTesting;
 import com.google.common.base.Equivalence;
 import com.google.common.base.Function;
 import com.google.common.collect.MapMaker.Dummy;
 import com.google.common.collect.MapMakerInternalMap.InternalEntry;
+import javax.annotation.CheckForNull;
 
 /**
  * Contains static methods pertaining to instances of {@link Interner}.
@@ -30,8 +30,8 @@
  * @author Kevin Bourrillion
  * @since 3.0
  */
-@Beta
 @GwtIncompatible
+@ElementTypesAreNonnullByDefault
 public final class Interners {
   private Interners() {}
 
@@ -81,7 +81,7 @@ public <E> Interner<E> build() {
       if (!strong) {
         mapMaker.weakKeys();
       }
-      return new InternerImpl<E>(mapMaker);
+      return new InternerImpl<>(mapMaker);
     }
   }
 
@@ -124,11 +124,15 @@ private InternerImpl(MapMaker mapMaker) {
     public E intern(E sample) {
       while (true) {
         // trying to read the canonical...
-        InternalEntry<E, Dummy, ?> entry = map.getEntry(sample);
+        @SuppressWarnings("rawtypes") // using raw types to avoid a bug in our nullness checker :(
+        InternalEntry entry = map.getEntry(sample);
         if (entry != null) {
-          E canonical = entry.getKey();
+          Object canonical = entry.getKey();
           if (canonical != null) { // only matters if weak/soft keys are used
-            return canonical;
+            // The compiler would know this is safe if not for our use of raw types (see above).
+            @SuppressWarnings("unchecked")
+            E result = (E) canonical;
+            return result;
           }
         }
 
@@ -154,7 +158,7 @@ public E intern(E sample) {
    * @since 8.0
    */
   public static <E> Function<E, E> asFunction(Interner<E> interner) {
-    return new InternerFunction<E>(checkNotNull(interner));
+    return new InternerFunction<>(checkNotNull(interner));
   }
 
   private static class InternerFunction<E> implements Function<E, E> {
@@ -176,7 +180,7 @@ public int hashCode() {
     }
 
     @Override
-    public boolean equals(Object other) {
+    public boolean equals(@CheckForNull Object other) {
       if (other instanceof InternerFunction) {
         InternerFunction<?> that = (InternerFunction<?>) other;
         return interner.equals(that.interner);
diff --git a/android/guava/src/com/google/common/collect/Iterables.java b/android/guava/src/com/google/common/collect/Iterables.java
index 08df7f28d580..08f8d45a1a17 100644
--- a/android/guava/src/com/google/common/collect/Iterables.java
+++ b/android/guava/src/com/google/common/collect/Iterables.java
@@ -36,7 +36,8 @@
 import java.util.Queue;
 import java.util.RandomAccess;
 import java.util.Set;
-import org.checkerframework.checker.nullness.compatqual.NullableDecl;
+import javax.annotation.CheckForNull;
+import org.checkerframework.checker.nullness.qual.Nullable;
 
 /**
  * An assortment of mainly legacy static utility methods that operate on or return objects of type
@@ -53,7 +54,7 @@
  * absolutely necessary.
  *
  * <p>See the Guava User Guide article on <a href=
- * "https://github.com/google/guava/wiki/CollectionUtilitiesExplained#iterables"> {@code
+ * "https://github.com/google/guava/wiki/CollectionUtilitiesExplained#iterables">{@code
  * Iterables}</a>.
  *
  * @author Kevin Bourrillion
@@ -61,11 +62,13 @@
  * @since 2.0
  */
 @GwtCompatible(emulated = true)
+@ElementTypesAreNonnullByDefault
 public final class Iterables {
   private Iterables() {}
 
   /** Returns an unmodifiable view of {@code iterable}. */
-  public static <T> Iterable<T> unmodifiableIterable(final Iterable<? extends T> iterable) {
+  public static <T extends @Nullable Object> Iterable<T> unmodifiableIterable(
+      final Iterable<? extends T> iterable) {
     checkNotNull(iterable);
     if (iterable instanceof UnmodifiableIterable || iterable instanceof ImmutableCollection) {
       @SuppressWarnings("unchecked") // Since it's unmodifiable, the covariant cast is safe
@@ -86,7 +89,8 @@ public static <E> Iterable<E> unmodifiableIterable(ImmutableCollection<E> iterab
     return checkNotNull(iterable);
   }
 
-  private static final class UnmodifiableIterable<T> extends FluentIterable<T> {
+  private static final class UnmodifiableIterable<T extends @Nullable Object>
+      extends FluentIterable<T> {
     private final Iterable<? extends T> iterable;
 
     private UnmodifiableIterable(Iterable<? extends T> iterable) {
@@ -118,7 +122,9 @@ public static int size(Iterable<?> iterable) {
    * cases where {@link Collection#contains} might throw {@link NullPointerException} or {@link
    * ClassCastException}.
    */
-  public static boolean contains(Iterable<?> iterable, @NullableDecl Object element) {
+  // <? extends @Nullable Object> instead of <?> because of Kotlin b/189937072, discussed in Joiner.
+  public static boolean contains(
+      Iterable<? extends @Nullable Object> iterable, @CheckForNull Object element) {
     if (iterable instanceof Collection) {
       Collection<?> collection = (Collection<?>) iterable;
       return Collections2.safeContains(collection, element);
@@ -174,14 +180,15 @@ public static boolean retainAll(Iterable<?> removeFrom, Collection<?> elementsTo
    * @since 2.0
    */
   @CanIgnoreReturnValue
-  public static <T> boolean removeIf(Iterable<T> removeFrom, Predicate<? super T> predicate) {
+  public static <T extends @Nullable Object> boolean removeIf(
+      Iterable<T> removeFrom, Predicate<? super T> predicate) {
     if (removeFrom instanceof RandomAccess && removeFrom instanceof List) {
       return removeIfFromRandomAccessList((List<T>) removeFrom, checkNotNull(predicate));
     }
     return Iterators.removeIf(removeFrom.iterator(), predicate);
   }
 
-  private static <T> boolean removeIfFromRandomAccessList(
+  private static <T extends @Nullable Object> boolean removeIfFromRandomAccessList(
       List<T> list, Predicate<? super T> predicate) {
     // Note: Not all random access lists support set(). Additionally, it's possible
     // for a list to reject setting an element, such as when the list does not permit
@@ -213,7 +220,7 @@ private static <T> boolean removeIfFromRandomAccessList(
     return from != to;
   }
 
-  private static <T> void slowRemoveIfForRemainingElements(
+  private static <T extends @Nullable Object> void slowRemoveIfForRemainingElements(
       List<T> list, Predicate<? super T> predicate, int to, int from) {
     // Here we know that:
     // * (to < from) and that both are valid indices.
@@ -237,8 +244,9 @@ private static <T> void slowRemoveIfForRemainingElements(
   }
 
   /** Removes and returns the first matching element, or returns {@code null} if there is none. */
-  @NullableDecl
-  static <T> T removeFirstMatching(Iterable<T> removeFrom, Predicate<? super T> predicate) {
+  @CheckForNull
+  static <T extends @Nullable Object> T removeFirstMatching(
+      Iterable<T> removeFrom, Predicate<? super T> predicate) {
     checkNotNull(predicate);
     Iterator<T> iterator = removeFrom.iterator();
     while (iterator.hasNext()) {
@@ -288,7 +296,8 @@ public static String toString(Iterable<?> iterable) {
    * @throws NoSuchElementException if the iterable is empty
    * @throws IllegalArgumentException if the iterable contains multiple elements
    */
-  public static <T> T getOnlyElement(Iterable<T> iterable) {
+  @ParametricNullness
+  public static <T extends @Nullable Object> T getOnlyElement(Iterable<T> iterable) {
     return Iterators.getOnlyElement(iterable.iterator());
   }
 
@@ -301,8 +310,9 @@ public static <T> T getOnlyElement(Iterable<T> iterable) {
    *
    * @throws IllegalArgumentException if the iterator contains multiple elements
    */
-  @NullableDecl
-  public static <T> T getOnlyElement(Iterable<? extends T> iterable, @NullableDecl T defaultValue) {
+  @ParametricNullness
+  public static <T extends @Nullable Object> T getOnlyElement(
+      Iterable<? extends T> iterable, @ParametricNullness T defaultValue) {
     return Iterators.getOnlyElement(iterable.iterator(), defaultValue);
   }
 
@@ -314,11 +324,16 @@ public static <T> T getOnlyElement(Iterable<? extends T> iterable, @NullableDecl
    * @return a newly-allocated array into which all the elements of the iterable have been copied
    */
   @GwtIncompatible // Array.newInstance(Class, int)
-  public static <T> T[] toArray(Iterable<? extends T> iterable, Class<T> type) {
+  /*
+   * If we could express Class<@Nonnull T>, we could generalize the type parameter to <T extends
+   * @Nullable Object>, and then we could accept an Iterable<? extends T> and return a plain T[]
+   * instead of a @Nullable T[].
+   */
+  public static <T> @Nullable T[] toArray(Iterable<? extends @Nullable T> iterable, Class<T> type) {
     return toArray(iterable, ObjectArrays.newArray(type, 0));
   }
 
-  static <T> T[] toArray(Iterable<? extends T> iterable, T[] array) {
+  static <T extends @Nullable Object> T[] toArray(Iterable<? extends T> iterable, T[] array) {
     Collection<? extends T> collection = castOrCopyToCollection(iterable);
     return collection.toArray(array);
   }
@@ -329,7 +344,7 @@ static <T> T[] toArray(Iterable<? extends T> iterable, T[] array) {
    * @param iterable the iterable to copy
    * @return a newly-allocated array into which all the elements of the iterable have been copied
    */
-  static Object[] toArray(Iterable<?> iterable) {
+  static @Nullable Object[] toArray(Iterable<?> iterable) {
     return castOrCopyToCollection(iterable).toArray();
   }
 
@@ -338,7 +353,8 @@ static Object[] toArray(Iterable<?> iterable) {
    * returned. Otherwise, an {@link java.util.ArrayList} is created with the contents of the
    * iterable in the same iteration order.
    */
-  private static <E> Collection<E> castOrCopyToCollection(Iterable<E> iterable) {
+  private static <E extends @Nullable Object> Collection<E> castOrCopyToCollection(
+      Iterable<E> iterable) {
     return (iterable instanceof Collection)
         ? (Collection<E>) iterable
         : Lists.newArrayList(iterable.iterator());
@@ -350,7 +366,8 @@ private static <E> Collection<E> castOrCopyToCollection(Iterable<E> iterable) {
    * @return {@code true} if {@code collection} was modified as a result of this operation.
    */
   @CanIgnoreReturnValue
-  public static <T> boolean addAll(Collection<T> addTo, Iterable<? extends T> elementsToAdd) {
+  public static <T extends @Nullable Object> boolean addAll(
+      Collection<T> addTo, Iterable<? extends T> elementsToAdd) {
     if (elementsToAdd instanceof Collection) {
       Collection<? extends T> c = (Collection<? extends T>) elementsToAdd;
       return addTo.addAll(c);
@@ -369,7 +386,7 @@ public static <T> boolean addAll(Collection<T> addTo, Iterable<? extends T> elem
    * @see java.util.Collections#frequency(Collection, Object) Collections.frequency(Collection,
    *     Object)
    */
-  public static int frequency(Iterable<?> iterable, @NullableDecl Object element) {
+  public static int frequency(Iterable<?> iterable, @CheckForNull Object element) {
     if ((iterable instanceof Multiset)) {
       return ((Multiset<?>) iterable).count(element);
     } else if ((iterable instanceof Set)) {
@@ -396,7 +413,7 @@ public static int frequency(Iterable<?> iterable, @NullableDecl Object element)
    * <p><b>Java 8 users:</b> The {@code Stream} equivalent of this method is {@code
    * Stream.generate(() -> iterable).flatMap(Streams::stream)}.
    */
-  public static <T> Iterable<T> cycle(final Iterable<T> iterable) {
+  public static <T extends @Nullable Object> Iterable<T> cycle(final Iterable<T> iterable) {
     checkNotNull(iterable);
     return new FluentIterable<T>() {
       @Override
@@ -432,7 +449,7 @@ public String toString() {
    * and use {@code Stream.generate(() -> collection).flatMap(Collection::stream)}.
    */
   @SafeVarargs
-  public static <T> Iterable<T> cycle(T... elements) {
+  public static <T extends @Nullable Object> Iterable<T> cycle(T... elements) {
     return cycle(Lists.newArrayList(elements));
   }
 
@@ -447,7 +464,8 @@ public static <T> Iterable<T> cycle(T... elements) {
    * <p><b>Java 8 users:</b> The {@code Stream} equivalent of this method is {@code Stream.concat(a,
    * b)}.
    */
-  public static <T> Iterable<T> concat(Iterable<? extends T> a, Iterable<? extends T> b) {
+  public static <T extends @Nullable Object> Iterable<T> concat(
+      Iterable<? extends T> a, Iterable<? extends T> b) {
     return FluentIterable.concat(a, b);
   }
 
@@ -462,7 +480,7 @@ public static <T> Iterable<T> concat(Iterable<? extends T> a, Iterable<? extends
    * <p><b>Java 8 users:</b> The {@code Stream} equivalent of this method is {@code
    * Streams.concat(a, b, c)}.
    */
-  public static <T> Iterable<T> concat(
+  public static <T extends @Nullable Object> Iterable<T> concat(
       Iterable<? extends T> a, Iterable<? extends T> b, Iterable<? extends T> c) {
     return FluentIterable.concat(a, b, c);
   }
@@ -479,7 +497,7 @@ public static <T> Iterable<T> concat(
    * <p><b>Java 8 users:</b> The {@code Stream} equivalent of this method is {@code
    * Streams.concat(a, b, c, d)}.
    */
-  public static <T> Iterable<T> concat(
+  public static <T extends @Nullable Object> Iterable<T> concat(
       Iterable<? extends T> a,
       Iterable<? extends T> b,
       Iterable<? extends T> c,
@@ -501,7 +519,7 @@ public static <T> Iterable<T> concat(
    * @throws NullPointerException if any of the provided iterables is null
    */
   @SafeVarargs
-  public static <T> Iterable<T> concat(Iterable<? extends T>... inputs) {
+  public static <T extends @Nullable Object> Iterable<T> concat(Iterable<? extends T>... inputs) {
     return FluentIterable.concat(inputs);
   }
 
@@ -517,7 +535,8 @@ public static <T> Iterable<T> concat(Iterable<? extends T>... inputs) {
    * <p><b>Java 8 users:</b> The {@code Stream} equivalent of this method is {@code
    * streamOfStreams.flatMap(s -> s)}.
    */
-  public static <T> Iterable<T> concat(Iterable<? extends Iterable<? extends T>> inputs) {
+  public static <T extends @Nullable Object> Iterable<T> concat(
+      Iterable<? extends Iterable<? extends T>> inputs) {
     return FluentIterable.concat(inputs);
   }
 
@@ -530,6 +549,10 @@ public static <T> Iterable<T> concat(Iterable<? extends Iterable<? extends T>> i
    * <p>Iterators returned by the returned iterable do not support the {@link Iterator#remove()}
    * method. The returned lists implement {@link RandomAccess}, whether or not the input list does.
    *
+   * <p><b>Note:</b> The current implementation eagerly allocates storage for {@code size} elements.
+   * As a consequence, passing values like {@code Integer.MAX_VALUE} can lead to {@link
+   * OutOfMemoryError}.
+   *
    * <p><b>Note:</b> if {@code iterable} is a {@link List}, use {@link Lists#partition(List, int)}
    * instead.
    *
@@ -539,7 +562,8 @@ public static <T> Iterable<T> concat(Iterable<? extends Iterable<? extends T>> i
    *     into partitions
    * @throws IllegalArgumentException if {@code size} is nonpositive
    */
-  public static <T> Iterable<List<T>> partition(final Iterable<T> iterable, final int size) {
+  public static <T extends @Nullable Object> Iterable<List<T>> partition(
+      final Iterable<T> iterable, final int size) {
     checkNotNull(iterable);
     checkArgument(size > 0);
     return new FluentIterable<List<T>>() {
@@ -565,12 +589,13 @@ public Iterator<List<T>> iterator() {
    *     into partitions (the final iterable may have trailing null elements)
    * @throws IllegalArgumentException if {@code size} is nonpositive
    */
-  public static <T> Iterable<List<T>> paddedPartition(final Iterable<T> iterable, final int size) {
+  public static <T extends @Nullable Object> Iterable<List<@Nullable T>> paddedPartition(
+      final Iterable<T> iterable, final int size) {
     checkNotNull(iterable);
     checkArgument(size > 0);
-    return new FluentIterable<List<T>>() {
+    return new FluentIterable<List<@Nullable T>>() {
       @Override
-      public Iterator<List<T>> iterator() {
+      public Iterator<List<@Nullable T>> iterator() {
         return Iterators.paddedPartition(iterable.iterator(), size);
       }
     };
@@ -582,7 +607,7 @@ public Iterator<List<T>> iterator() {
    *
    * <p><b>{@code Stream} equivalent:</b> {@link Stream#filter}.
    */
-  public static <T> Iterable<T> filter(
+  public static <T extends @Nullable Object> Iterable<T> filter(
       final Iterable<T> unfiltered, final Predicate<? super T> retainIfTrue) {
     checkNotNull(unfiltered);
     checkNotNull(retainIfTrue);
@@ -621,7 +646,8 @@ public static <T> Iterable<T> filter(final Iterable<?> unfiltered, final Class<T
    *
    * <p><b>{@code Stream} equivalent:</b> {@link Stream#anyMatch}.
    */
-  public static <T> boolean any(Iterable<T> iterable, Predicate<? super T> predicate) {
+  public static <T extends @Nullable Object> boolean any(
+      Iterable<T> iterable, Predicate<? super T> predicate) {
     return Iterators.any(iterable.iterator(), predicate);
   }
 
@@ -631,7 +657,8 @@ public static <T> boolean any(Iterable<T> iterable, Predicate<? super T> predica
    *
    * <p><b>{@code Stream} equivalent:</b> {@link Stream#allMatch}.
    */
-  public static <T> boolean all(Iterable<T> iterable, Predicate<? super T> predicate) {
+  public static <T extends @Nullable Object> boolean all(
+      Iterable<T> iterable, Predicate<? super T> predicate) {
     return Iterators.all(iterable.iterator(), predicate);
   }
 
@@ -644,7 +671,9 @@ public static <T> boolean all(Iterable<T> iterable, Predicate<? super T> predica
    *
    * @throws NoSuchElementException if no element in {@code iterable} matches the given predicate
    */
-  public static <T> T find(Iterable<T> iterable, Predicate<? super T> predicate) {
+  @ParametricNullness
+  public static <T extends @Nullable Object> T find(
+      Iterable<T> iterable, Predicate<? super T> predicate) {
     return Iterators.find(iterable.iterator(), predicate);
   }
 
@@ -658,11 +687,26 @@ public static <T> T find(Iterable<T> iterable, Predicate<? super T> predicate) {
    *
    * @since 7.0
    */
-  @NullableDecl
-  public static <T> T find(
+  // The signature we really want here is...
+  //
+  // <T extends @Nullable Object> @JointlyNullable T find(
+  //     Iterable<? extends T> iterable,
+  //     Predicate<? super T> predicate,
+  //     @JointlyNullable T defaultValue);
+  //
+  // ...where "@JointlyNullable" is similar to @PolyNull but slightly different:
+  //
+  // - @PolyNull means "@Nullable or @Nonnull"
+  //   (That would be unsound for an input Iterable<@Nullable Foo>. So, if we wanted to use
+  //   @PolyNull, we would have to restrict this method to non-null <T>. But it has users who pass
+  //   iterables with null elements.)
+  //
+  // - @JointlyNullable means "@Nullable or no annotation"
+  @CheckForNull
+  public static <T extends @Nullable Object> T find(
       Iterable<? extends T> iterable,
       Predicate<? super T> predicate,
-      @NullableDecl T defaultValue) {
+      @CheckForNull T defaultValue) {
     return Iterators.find(iterable.iterator(), predicate, defaultValue);
   }
 
@@ -691,7 +735,8 @@ public static <T> Optional<T> tryFind(Iterable<T> iterable, Predicate<? super T>
    *
    * @since 2.0
    */
-  public static <T> int indexOf(Iterable<T> iterable, Predicate<? super T> predicate) {
+  public static <T extends @Nullable Object> int indexOf(
+      Iterable<T> iterable, Predicate<? super T> predicate) {
     return Iterators.indexOf(iterable.iterator(), predicate);
   }
 
@@ -708,7 +753,7 @@ public static <T> int indexOf(Iterable<T> iterable, Predicate<? super T> predica
    *
    * <p><b>{@code Stream} equivalent:</b> {@link Stream#map}
    */
-  public static <F, T> Iterable<T> transform(
+  public static <F extends @Nullable Object, T extends @Nullable Object> Iterable<T> transform(
       final Iterable<F> fromIterable, final Function<? super F, ? extends T> function) {
     checkNotNull(fromIterable);
     checkNotNull(function);
@@ -731,7 +776,8 @@ public Iterator<T> iterator() {
    * @throws IndexOutOfBoundsException if {@code position} is negative or greater than or equal to
    *     the size of {@code iterable}
    */
-  public static <T> T get(Iterable<T> iterable, int position) {
+  @ParametricNullness
+  public static <T extends @Nullable Object> T get(Iterable<T> iterable, int position) {
     checkNotNull(iterable);
     return (iterable instanceof List)
         ? ((List<T>) iterable).get(position)
@@ -753,9 +799,9 @@ public static <T> T get(Iterable<T> iterable, int position) {
    * @throws IndexOutOfBoundsException if {@code position} is negative
    * @since 4.0
    */
-  @NullableDecl
-  public static <T> T get(
-      Iterable<? extends T> iterable, int position, @NullableDecl T defaultValue) {
+  @ParametricNullness
+  public static <T extends @Nullable Object> T get(
+      Iterable<? extends T> iterable, int position, @ParametricNullness T defaultValue) {
     checkNotNull(iterable);
     Iterators.checkNonnegative(position);
     if (iterable instanceof List) {
@@ -785,8 +831,9 @@ public static <T> T get(
    * @return the first element of {@code iterable} or the default value
    * @since 7.0
    */
-  @NullableDecl
-  public static <T> T getFirst(Iterable<? extends T> iterable, @NullableDecl T defaultValue) {
+  @ParametricNullness
+  public static <T extends @Nullable Object> T getFirst(
+      Iterable<? extends T> iterable, @ParametricNullness T defaultValue) {
     return Iterators.getNext(iterable.iterator(), defaultValue);
   }
 
@@ -799,7 +846,8 @@ public static <T> T getFirst(Iterable<? extends T> iterable, @NullableDecl T def
    * @return the last element of {@code iterable}
    * @throws NoSuchElementException if the iterable is empty
    */
-  public static <T> T getLast(Iterable<T> iterable) {
+  @ParametricNullness
+  public static <T extends @Nullable Object> T getLast(Iterable<T> iterable) {
     // TODO(kevinb): Support a concurrently modified collection?
     if (iterable instanceof List) {
       List<T> list = (List<T>) iterable;
@@ -823,8 +871,9 @@ public static <T> T getLast(Iterable<T> iterable) {
    * @return the last element of {@code iterable} or the default value
    * @since 3.0
    */
-  @NullableDecl
-  public static <T> T getLast(Iterable<? extends T> iterable, @NullableDecl T defaultValue) {
+  @ParametricNullness
+  public static <T extends @Nullable Object> T getLast(
+      Iterable<? extends T> iterable, @ParametricNullness T defaultValue) {
     if (iterable instanceof Collection) {
       Collection<? extends T> c = (Collection<? extends T>) iterable;
       if (c.isEmpty()) {
@@ -837,7 +886,8 @@ public static <T> T getLast(Iterable<? extends T> iterable, @NullableDecl T defa
     return Iterators.getLast(iterable.iterator(), defaultValue);
   }
 
-  private static <T> T getLastInNonemptyList(List<T> list) {
+  @ParametricNullness
+  private static <T extends @Nullable Object> T getLastInNonemptyList(List<T> list) {
     return list.get(list.size() - 1);
   }
 
@@ -860,7 +910,8 @@ private static <T> T getLastInNonemptyList(List<T> list) {
    *
    * @since 3.0
    */
-  public static <T> Iterable<T> skip(final Iterable<T> iterable, final int numberToSkip) {
+  public static <T extends @Nullable Object> Iterable<T> skip(
+      final Iterable<T> iterable, final int numberToSkip) {
     checkNotNull(iterable);
     checkArgument(numberToSkip >= 0, "number to skip cannot be negative");
 
@@ -890,6 +941,7 @@ public boolean hasNext() {
           }
 
           @Override
+          @ParametricNullness
           public T next() {
             T result = iterator.next();
             atStart = false; // not called if next() fails
@@ -919,7 +971,8 @@ public void remove() {
    * @throws IllegalArgumentException if {@code limitSize} is negative
    * @since 3.0
    */
-  public static <T> Iterable<T> limit(final Iterable<T> iterable, final int limitSize) {
+  public static <T extends @Nullable Object> Iterable<T> limit(
+      final Iterable<T> iterable, final int limitSize) {
     checkNotNull(iterable);
     checkArgument(limitSize >= 0, "limit is negative");
     return new FluentIterable<T>() {
@@ -946,7 +999,8 @@ public Iterator<T> iterator() {
    * @see Iterators#consumingIterator(Iterator)
    * @since 2.0
    */
-  public static <T> Iterable<T> consumingIterable(final Iterable<T> iterable) {
+  public static <T extends @Nullable Object> Iterable<T> consumingIterable(
+      final Iterable<T> iterable) {
     checkNotNull(iterable);
 
     return new FluentIterable<T>() {
@@ -997,7 +1051,7 @@ public static boolean isEmpty(Iterable<?> iterable) {
    * @since 11.0
    */
   @Beta
-  public static <T> Iterable<T> mergeSorted(
+  public static <T extends @Nullable Object> Iterable<T> mergeSorted(
       final Iterable<? extends Iterable<? extends T>> iterables,
       final Comparator<? super T> comparator) {
     checkNotNull(iterables, "iterables");
@@ -1015,7 +1069,8 @@ public Iterator<T> iterator() {
 
   // TODO(user): Is this the best place for this? Move to fluent functions?
   // Useful as a public method?
-  static <T> Function<Iterable<? extends T>, Iterator<? extends T>> toIterator() {
+  static <T extends @Nullable Object>
+      Function<Iterable<? extends T>, Iterator<? extends T>> toIterator() {
     return new Function<Iterable<? extends T>, Iterator<? extends T>>() {
       @Override
       public Iterator<? extends T> apply(Iterable<? extends T> iterable) {
diff --git a/android/guava/src/com/google/common/collect/Iterators.java b/android/guava/src/com/google/common/collect/Iterators.java
index ac36b202c3ab..2f9fd3b4aa11 100644
--- a/android/guava/src/com/google/common/collect/Iterators.java
+++ b/android/guava/src/com/google/common/collect/Iterators.java
@@ -21,6 +21,8 @@
 import static com.google.common.base.Preconditions.checkState;
 import static com.google.common.base.Predicates.instanceOf;
 import static com.google.common.collect.CollectPreconditions.checkRemove;
+import static com.google.common.collect.NullnessCasts.uncheckedCastNullableTToT;
+import static java.util.Objects.requireNonNull;
 
 import com.google.common.annotations.Beta;
 import com.google.common.annotations.GwtCompatible;
@@ -45,7 +47,8 @@
 import java.util.NoSuchElementException;
 import java.util.PriorityQueue;
 import java.util.Queue;
-import org.checkerframework.checker.nullness.compatqual.NullableDecl;
+import javax.annotation.CheckForNull;
+import org.checkerframework.checker.nullness.qual.Nullable;
 
 /**
  * This class contains static utility methods that operate on or return objects of type {@link
@@ -57,7 +60,7 @@
  * necessary.
  *
  * <p>See the Guava User Guide section on <a href=
- * "https://github.com/google/guava/wiki/CollectionUtilitiesExplained#iterables"> {@code
+ * "https://github.com/google/guava/wiki/CollectionUtilitiesExplained#iterables">{@code
  * Iterators}</a>.
  *
  * @author Kevin Bourrillion
@@ -65,6 +68,7 @@
  * @since 2.0
  */
 @GwtCompatible(emulated = true)
+@ElementTypesAreNonnullByDefault
 public final class Iterators {
   private Iterators() {}
 
@@ -73,7 +77,7 @@ private Iterators() {}
    *
    * <p>The {@link Iterable} equivalent of this method is {@link ImmutableSet#of()}.
    */
-  static <T> UnmodifiableIterator<T> emptyIterator() {
+  static <T extends @Nullable Object> UnmodifiableIterator<T> emptyIterator() {
     return emptyListIterator();
   }
 
@@ -84,7 +88,7 @@ static <T> UnmodifiableIterator<T> emptyIterator() {
    */
   // Casting to any type is safe since there are no actual elements.
   @SuppressWarnings("unchecked")
-  static <T> UnmodifiableListIterator<T> emptyListIterator() {
+  static <T extends @Nullable Object> UnmodifiableListIterator<T> emptyListIterator() {
     return (UnmodifiableListIterator<T>) ArrayItr.EMPTY;
   }
 
@@ -117,13 +121,13 @@ public void remove() {
    */
   // Casting to any type is safe since there are no actual elements.
   @SuppressWarnings("unchecked")
-  static <T> Iterator<T> emptyModifiableIterator() {
+  static <T extends @Nullable Object> Iterator<T> emptyModifiableIterator() {
     return (Iterator<T>) EmptyModifiableIterator.INSTANCE;
   }
 
   /** Returns an unmodifiable view of {@code iterator}. */
-  public static <T> UnmodifiableIterator<T> unmodifiableIterator(
-      final Iterator<? extends T> iterator) {
+  public static <T extends @Nullable Object> UnmodifiableIterator<T> unmodifiableIterator(
+      Iterator<? extends T> iterator) {
     checkNotNull(iterator);
     if (iterator instanceof UnmodifiableIterator) {
       @SuppressWarnings("unchecked") // Since it's unmodifiable, the covariant cast is safe
@@ -137,6 +141,7 @@ public boolean hasNext() {
       }
 
       @Override
+      @ParametricNullness
       public T next() {
         return iterator.next();
       }
@@ -150,7 +155,8 @@ public T next() {
    * @since 10.0
    */
   @Deprecated
-  public static <T> UnmodifiableIterator<T> unmodifiableIterator(UnmodifiableIterator<T> iterator) {
+  public static <T extends @Nullable Object> UnmodifiableIterator<T> unmodifiableIterator(
+      UnmodifiableIterator<T> iterator) {
     return checkNotNull(iterator);
   }
 
@@ -168,7 +174,7 @@ public static int size(Iterator<?> iterator) {
   }
 
   /** Returns {@code true} if {@code iterator} contains {@code element}. */
-  public static boolean contains(Iterator<?> iterator, @NullableDecl Object element) {
+  public static boolean contains(Iterator<?> iterator, @CheckForNull Object element) {
     if (element == null) {
       while (iterator.hasNext()) {
         if (iterator.next() == null) {
@@ -216,7 +222,8 @@ public static boolean removeAll(Iterator<?> removeFrom, Collection<?> elementsTo
    * @since 2.0
    */
   @CanIgnoreReturnValue
-  public static <T> boolean removeIf(Iterator<T> removeFrom, Predicate<? super T> predicate) {
+  public static <T extends @Nullable Object> boolean removeIf(
+      Iterator<T> removeFrom, Predicate<? super T> predicate) {
     checkNotNull(predicate);
     boolean modified = false;
     while (removeFrom.hasNext()) {
@@ -297,7 +304,8 @@ public static String toString(Iterator<?> iterator) {
    * @throws IllegalArgumentException if the iterator contains multiple elements. The state of the
    *     iterator is unspecified.
    */
-  public static <T> T getOnlyElement(Iterator<T> iterator) {
+  @ParametricNullness
+  public static <T extends @Nullable Object> T getOnlyElement(Iterator<T> iterator) {
     T first = iterator.next();
     if (!iterator.hasNext()) {
       return first;
@@ -322,8 +330,9 @@ public static <T> T getOnlyElement(Iterator<T> iterator) {
    * @throws IllegalArgumentException if the iterator contains multiple elements. The state of the
    *     iterator is unspecified.
    */
-  @NullableDecl
-  public static <T> T getOnlyElement(Iterator<? extends T> iterator, @NullableDecl T defaultValue) {
+  @ParametricNullness
+  public static <T extends @Nullable Object> T getOnlyElement(
+      Iterator<? extends T> iterator, @ParametricNullness T defaultValue) {
     return iterator.hasNext() ? getOnlyElement(iterator) : defaultValue;
   }
 
@@ -336,8 +345,9 @@ public static <T> T getOnlyElement(Iterator<? extends T> iterator, @NullableDecl
    * @return a newly-allocated array into which all the elements of the iterator have been copied
    */
   @GwtIncompatible // Array.newInstance(Class, int)
-  public static <T> T[] toArray(Iterator<? extends T> iterator, Class<T> type) {
-    List<T> list = Lists.newArrayList(iterator);
+  // For discussion of this signature, see the corresponding overload of *Iterables*.toArray.
+  public static <T> @Nullable T[] toArray(Iterator<? extends @Nullable T> iterator, Class<T> type) {
+    List<@Nullable T> list = Lists.newArrayList(iterator);
     return Iterables.toArray(list, type);
   }
 
@@ -348,7 +358,8 @@ public static <T> T[] toArray(Iterator<? extends T> iterator, Class<T> type) {
    * @return {@code true} if {@code collection} was modified as a result of this operation
    */
   @CanIgnoreReturnValue
-  public static <T> boolean addAll(Collection<T> addTo, Iterator<? extends T> iterator) {
+  public static <T extends @Nullable Object> boolean addAll(
+      Collection<T> addTo, Iterator<? extends T> iterator) {
     checkNotNull(addTo);
     checkNotNull(iterator);
     boolean wasModified = false;
@@ -364,7 +375,7 @@ public static <T> boolean addAll(Collection<T> addTo, Iterator<? extends T> iter
    *
    * @see Collections#frequency
    */
-  public static int frequency(Iterator<?> iterator, @NullableDecl Object element) {
+  public static int frequency(Iterator<?> iterator, @CheckForNull Object element) {
     int count = 0;
     while (contains(iterator, element)) {
       // Since it lives in the same class, we know contains gets to the element and then stops,
@@ -386,7 +397,7 @@ public static int frequency(Iterator<?> iterator, @NullableDecl Object element)
    * should use an explicit {@code break} or be certain that you will eventually remove all the
    * elements.
    */
-  public static <T> Iterator<T> cycle(final Iterable<T> iterable) {
+  public static <T extends @Nullable Object> Iterator<T> cycle(Iterable<T> iterable) {
     checkNotNull(iterable);
     return new Iterator<T>() {
       Iterator<T> iterator = emptyModifiableIterator();
@@ -406,6 +417,7 @@ public boolean hasNext() {
       }
 
       @Override
+      @ParametricNullness
       public T next() {
         if (!iterator.hasNext()) {
           iterator = iterable.iterator();
@@ -436,7 +448,7 @@ public void remove() {
    * elements.
    */
   @SafeVarargs
-  public static <T> Iterator<T> cycle(T... elements) {
+  public static <T extends @Nullable Object> Iterator<T> cycle(T... elements) {
     return cycle(Lists.newArrayList(elements));
   }
 
@@ -444,10 +456,14 @@ public static <T> Iterator<T> cycle(T... elements) {
    * Returns an Iterator that walks the specified array, nulling out elements behind it. This can
    * avoid memory leaks when an element is no longer necessary.
    *
+   * <p>This method accepts an array with element type {@code @Nullable T}, but callers must pass an
+   * array whose contents are initially non-null. The {@code @Nullable} annotation indicates that
+   * this method will write nulls into the array during iteration.
+   *
    * <p>This is mainly just to avoid the intermediate ArrayDeque in ConsumingQueueIterator.
    */
-  private static <T> Iterator<T> consumingForArray(final T... elements) {
-    return new UnmodifiableIterator<T>() {
+  private static <I extends Iterator<?>> Iterator<I> consumingForArray(@Nullable I... elements) {
+    return new UnmodifiableIterator<I>() {
       int index = 0;
 
       @Override
@@ -456,11 +472,15 @@ public boolean hasNext() {
       }
 
       @Override
-      public T next() {
+      public I next() {
         if (!hasNext()) {
           throw new NoSuchElementException();
         }
-        T result = elements[index];
+        /*
+         * requireNonNull is safe because our callers always pass non-null arguments. Each element
+         * of the array becomes null only when we iterate past it and then clear it.
+         */
+        I result = requireNonNull(elements[index]);
         elements[index] = null;
         index++;
         return result;
@@ -476,7 +496,8 @@ public T next() {
    * <p>The returned iterator supports {@code remove()} when the corresponding input iterator
    * supports it.
    */
-  public static <T> Iterator<T> concat(Iterator<? extends T> a, Iterator<? extends T> b) {
+  public static <T extends @Nullable Object> Iterator<T> concat(
+      Iterator<? extends T> a, Iterator<? extends T> b) {
     checkNotNull(a);
     checkNotNull(b);
     return concat(consumingForArray(a, b));
@@ -490,7 +511,7 @@ public static <T> Iterator<T> concat(Iterator<? extends T> a, Iterator<? extends
    * <p>The returned iterator supports {@code remove()} when the corresponding input iterator
    * supports it.
    */
-  public static <T> Iterator<T> concat(
+  public static <T extends @Nullable Object> Iterator<T> concat(
       Iterator<? extends T> a, Iterator<? extends T> b, Iterator<? extends T> c) {
     checkNotNull(a);
     checkNotNull(b);
@@ -507,7 +528,7 @@ public static <T> Iterator<T> concat(
    * <p>The returned iterator supports {@code remove()} when the corresponding input iterator
    * supports it.
    */
-  public static <T> Iterator<T> concat(
+  public static <T extends @Nullable Object> Iterator<T> concat(
       Iterator<? extends T> a,
       Iterator<? extends T> b,
       Iterator<? extends T> c,
@@ -529,7 +550,7 @@ public static <T> Iterator<T> concat(
    *
    * @throws NullPointerException if any of the provided iterators is null
    */
-  public static <T> Iterator<T> concat(Iterator<? extends T>... inputs) {
+  public static <T extends @Nullable Object> Iterator<T> concat(Iterator<? extends T>... inputs) {
     return concatNoDefensiveCopy(Arrays.copyOf(inputs, inputs.length));
   }
 
@@ -542,12 +563,14 @@ public static <T> Iterator<T> concat(Iterator<? extends T>... inputs) {
    * supports it. The methods of the returned iterator may throw {@code NullPointerException} if any
    * of the input iterators is null.
    */
-  public static <T> Iterator<T> concat(Iterator<? extends Iterator<? extends T>> inputs) {
-    return new ConcatenatedIterator<T>(inputs);
+  public static <T extends @Nullable Object> Iterator<T> concat(
+      Iterator<? extends Iterator<? extends T>> inputs) {
+    return new ConcatenatedIterator<>(inputs);
   }
 
   /** Concats a varargs array of iterators without making a defensive copy of the array. */
-  static <T> Iterator<T> concatNoDefensiveCopy(Iterator<? extends T>... inputs) {
+  static <T extends @Nullable Object> Iterator<T> concatNoDefensiveCopy(
+      Iterator<? extends T>... inputs) {
     for (Iterator<? extends T> input : checkNotNull(inputs)) {
       checkNotNull(input);
     }
@@ -562,13 +585,18 @@ static <T> Iterator<T> concatNoDefensiveCopy(Iterator<? extends T>... inputs) {
    *
    * <p>The returned lists implement {@link java.util.RandomAccess}.
    *
+   * <p><b>Note:</b> The current implementation eagerly allocates storage for {@code size} elements.
+   * As a consequence, passing values like {@code Integer.MAX_VALUE} can lead to {@link
+   * OutOfMemoryError}.
+   *
    * @param iterator the iterator to return a partitioned view of
    * @param size the desired size of each partition (the last may be smaller)
    * @return an iterator of immutable lists containing the elements of {@code iterator} divided into
    *     partitions
    * @throws IllegalArgumentException if {@code size} is nonpositive
    */
-  public static <T> UnmodifiableIterator<List<T>> partition(Iterator<T> iterator, int size) {
+  public static <T extends @Nullable Object> UnmodifiableIterator<List<T>> partition(
+      Iterator<T> iterator, int size) {
     return partitionImpl(iterator, size, false);
   }
 
@@ -586,26 +614,29 @@ public static <T> UnmodifiableIterator<List<T>> partition(Iterator<T> iterator,
    *     partitions (the final iterable may have trailing null elements)
    * @throws IllegalArgumentException if {@code size} is nonpositive
    */
-  public static <T> UnmodifiableIterator<List<T>> paddedPartition(Iterator<T> iterator, int size) {
+  public static <T extends @Nullable Object>
+      UnmodifiableIterator<List<@Nullable T>> paddedPartition(Iterator<T> iterator, int size) {
     return partitionImpl(iterator, size, true);
   }
 
-  private static <T> UnmodifiableIterator<List<T>> partitionImpl(
-      final Iterator<T> iterator, final int size, final boolean pad) {
+  private static <T extends @Nullable Object> UnmodifiableIterator<List<@Nullable T>> partitionImpl(
+      Iterator<T> iterator, int size, boolean pad) {
     checkNotNull(iterator);
     checkArgument(size > 0);
-    return new UnmodifiableIterator<List<T>>() {
+    return new UnmodifiableIterator<List<@Nullable T>>() {
       @Override
       public boolean hasNext() {
         return iterator.hasNext();
       }
 
       @Override
-      public List<T> next() {
+      public List<@Nullable T> next() {
         if (!hasNext()) {
           throw new NoSuchElementException();
         }
-        Object[] array = new Object[size];
+        @SuppressWarnings("unchecked") // we only put Ts in it
+        @Nullable
+        T[] array = (@Nullable T[]) new Object[size];
         int count = 0;
         for (; count < size && iterator.hasNext(); count++) {
           array[count] = iterator.next();
@@ -614,9 +645,13 @@ public List<T> next() {
           array[i] = null; // for GWT
         }
 
-        @SuppressWarnings("unchecked") // we only put Ts in it
-        List<T> list = Collections.unmodifiableList((List<T>) Arrays.asList(array));
-        return (pad || count == size) ? list : list.subList(0, count);
+        List<@Nullable T> list = Collections.unmodifiableList(Arrays.asList(array));
+        // TODO(b/192579700): Use a ternary once it no longer confuses our nullness checker.
+        if (pad || count == size) {
+          return list;
+        } else {
+          return list.subList(0, count);
+        }
       }
     };
   }
@@ -625,12 +660,13 @@ public List<T> next() {
    * Returns a view of {@code unfiltered} containing all elements that satisfy the input predicate
    * {@code retainIfTrue}.
    */
-  public static <T> UnmodifiableIterator<T> filter(
-      final Iterator<T> unfiltered, final Predicate<? super T> retainIfTrue) {
+  public static <T extends @Nullable Object> UnmodifiableIterator<T> filter(
+      Iterator<T> unfiltered, Predicate<? super T> retainIfTrue) {
     checkNotNull(unfiltered);
     checkNotNull(retainIfTrue);
     return new AbstractIterator<T>() {
       @Override
+      @CheckForNull
       protected T computeNext() {
         while (unfiltered.hasNext()) {
           T element = unfiltered.next();
@@ -657,7 +693,8 @@ public static <T> UnmodifiableIterator<T> filter(Iterator<?> unfiltered, Class<T
    * Returns {@code true} if one or more elements returned by {@code iterator} satisfy the given
    * predicate.
    */
-  public static <T> boolean any(Iterator<T> iterator, Predicate<? super T> predicate) {
+  public static <T extends @Nullable Object> boolean any(
+      Iterator<T> iterator, Predicate<? super T> predicate) {
     return indexOf(iterator, predicate) != -1;
   }
 
@@ -665,7 +702,8 @@ public static <T> boolean any(Iterator<T> iterator, Predicate<? super T> predica
    * Returns {@code true} if every element returned by {@code iterator} satisfies the given
    * predicate. If {@code iterator} is empty, {@code true} is returned.
    */
-  public static <T> boolean all(Iterator<T> iterator, Predicate<? super T> predicate) {
+  public static <T extends @Nullable Object> boolean all(
+      Iterator<T> iterator, Predicate<? super T> predicate) {
     checkNotNull(predicate);
     while (iterator.hasNext()) {
       T element = iterator.next();
@@ -685,7 +723,9 @@ public static <T> boolean all(Iterator<T> iterator, Predicate<? super T> predica
    *
    * @throws NoSuchElementException if no element in {@code iterator} matches the given predicate
    */
-  public static <T> T find(Iterator<T> iterator, Predicate<? super T> predicate) {
+  @ParametricNullness
+  public static <T extends @Nullable Object> T find(
+      Iterator<T> iterator, Predicate<? super T> predicate) {
     checkNotNull(iterator);
     checkNotNull(predicate);
     while (iterator.hasNext()) {
@@ -705,11 +745,12 @@ public static <T> T find(Iterator<T> iterator, Predicate<? super T> predicate) {
    *
    * @since 7.0
    */
-  @NullableDecl
-  public static <T> T find(
+  // For discussion of this signature, see the corresponding overload of *Iterables*.find.
+  @CheckForNull
+  public static <T extends @Nullable Object> T find(
       Iterator<? extends T> iterator,
       Predicate<? super T> predicate,
-      @NullableDecl T defaultValue) {
+      @CheckForNull T defaultValue) {
     checkNotNull(iterator);
     checkNotNull(predicate);
     while (iterator.hasNext()) {
@@ -758,7 +799,8 @@ public static <T> Optional<T> tryFind(Iterator<T> iterator, Predicate<? super T>
    *
    * @since 2.0
    */
-  public static <T> int indexOf(Iterator<T> iterator, Predicate<? super T> predicate) {
+  public static <T extends @Nullable Object> int indexOf(
+      Iterator<T> iterator, Predicate<? super T> predicate) {
     checkNotNull(predicate, "predicate");
     for (int i = 0; iterator.hasNext(); i++) {
       T current = iterator.next();
@@ -777,12 +819,13 @@ public static <T> int indexOf(Iterator<T> iterator, Predicate<? super T> predica
    * successful {@code remove()} call, {@code fromIterator} no longer contains the corresponding
    * element.
    */
-  public static <F, T> Iterator<T> transform(
-      final Iterator<F> fromIterator, final Function<? super F, ? extends T> function) {
+  public static <F extends @Nullable Object, T extends @Nullable Object> Iterator<T> transform(
+      Iterator<F> fromIterator, Function<? super F, ? extends T> function) {
     checkNotNull(function);
     return new TransformedIterator<F, T>(fromIterator) {
+      @ParametricNullness
       @Override
-      T transform(F from) {
+      T transform(@ParametricNullness F from) {
         return function.apply(from);
       }
     };
@@ -797,7 +840,8 @@ T transform(F from) {
    * @throws IndexOutOfBoundsException if {@code position} is negative or greater than or equal to
    *     the number of elements remaining in {@code iterator}
    */
-  public static <T> T get(Iterator<T> iterator, int position) {
+  @ParametricNullness
+  public static <T extends @Nullable Object> T get(Iterator<T> iterator, int position) {
     checkNonnegative(position);
     int skipped = advance(iterator, position);
     if (!iterator.hasNext()) {
@@ -823,9 +867,9 @@ public static <T> T get(Iterator<T> iterator, int position) {
    * @throws IndexOutOfBoundsException if {@code position} is negative
    * @since 4.0
    */
-  @NullableDecl
-  public static <T> T get(
-      Iterator<? extends T> iterator, int position, @NullableDecl T defaultValue) {
+  @ParametricNullness
+  public static <T extends @Nullable Object> T get(
+      Iterator<? extends T> iterator, int position, @ParametricNullness T defaultValue) {
     checkNonnegative(position);
     advance(iterator, position);
     return getNext(iterator, defaultValue);
@@ -845,8 +889,9 @@ static void checkNonnegative(int position) {
    * @return the next element of {@code iterator} or the default value
    * @since 7.0
    */
-  @NullableDecl
-  public static <T> T getNext(Iterator<? extends T> iterator, @NullableDecl T defaultValue) {
+  @ParametricNullness
+  public static <T extends @Nullable Object> T getNext(
+      Iterator<? extends T> iterator, @ParametricNullness T defaultValue) {
     return iterator.hasNext() ? iterator.next() : defaultValue;
   }
 
@@ -856,7 +901,8 @@ public static <T> T getNext(Iterator<? extends T> iterator, @NullableDecl T defa
    * @return the last element of {@code iterator}
    * @throws NoSuchElementException if the iterator is empty
    */
-  public static <T> T getLast(Iterator<T> iterator) {
+  @ParametricNullness
+  public static <T extends @Nullable Object> T getLast(Iterator<T> iterator) {
     while (true) {
       T current = iterator.next();
       if (!iterator.hasNext()) {
@@ -873,8 +919,9 @@ public static <T> T getLast(Iterator<T> iterator) {
    * @return the last element of {@code iterator}
    * @since 3.0
    */
-  @NullableDecl
-  public static <T> T getLast(Iterator<? extends T> iterator, @NullableDecl T defaultValue) {
+  @ParametricNullness
+  public static <T extends @Nullable Object> T getLast(
+      Iterator<? extends T> iterator, @ParametricNullness T defaultValue) {
     return iterator.hasNext() ? getLast(iterator) : defaultValue;
   }
 
@@ -907,7 +954,8 @@ public static int advance(Iterator<?> iterator, int numberToAdvance) {
    * @throws IllegalArgumentException if {@code limitSize} is negative
    * @since 3.0
    */
-  public static <T> Iterator<T> limit(final Iterator<T> iterator, final int limitSize) {
+  public static <T extends @Nullable Object> Iterator<T> limit(
+      Iterator<T> iterator, int limitSize) {
     checkNotNull(iterator);
     checkArgument(limitSize >= 0, "limit is negative");
     return new Iterator<T>() {
@@ -919,6 +967,7 @@ public boolean hasNext() {
       }
 
       @Override
+      @ParametricNullness
       public T next() {
         if (!hasNext()) {
           throw new NoSuchElementException();
@@ -945,7 +994,7 @@ public void remove() {
    * @return an iterator that removes and returns elements from the supplied iterator
    * @since 2.0
    */
-  public static <T> Iterator<T> consumingIterator(final Iterator<T> iterator) {
+  public static <T extends @Nullable Object> Iterator<T> consumingIterator(Iterator<T> iterator) {
     checkNotNull(iterator);
     return new UnmodifiableIterator<T>() {
       @Override
@@ -954,6 +1003,7 @@ public boolean hasNext() {
       }
 
       @Override
+      @ParametricNullness
       public T next() {
         T next = iterator.next();
         iterator.remove();
@@ -971,8 +1021,8 @@ public String toString() {
    * Deletes and returns the next value from the iterator, or returns {@code null} if there is no
    * such value.
    */
-  @NullableDecl
-  static <T> T pollNext(Iterator<T> iterator) {
+  @CheckForNull
+  static <T extends @Nullable Object> T pollNext(Iterator<T> iterator) {
     if (iterator.hasNext()) {
       T result = iterator.next();
       iterator.remove();
@@ -1004,7 +1054,7 @@ static void clear(Iterator<?> iterator) {
    * {@link ImmutableList#copyOf(Object[])}}, or {@link ImmutableList#of}.
    */
   @SafeVarargs
-  public static <T> UnmodifiableIterator<T> forArray(final T... array) {
+  public static <T extends @Nullable Object> UnmodifiableIterator<T> forArray(T... array) {
     return forArray(array, 0, array.length, 0);
   }
 
@@ -1015,8 +1065,8 @@ public static <T> UnmodifiableIterator<T> forArray(final T... array) {
    * <p>The {@code Iterable} equivalent of this method is {@code
    * Arrays.asList(array).subList(offset, offset + length).listIterator(index)}.
    */
-  static <T> UnmodifiableListIterator<T> forArray(
-      final T[] array, final int offset, int length, int index) {
+  static <T extends @Nullable Object> UnmodifiableListIterator<T> forArray(
+      T[] array, int offset, int length, int index) {
     checkArgument(length >= 0);
     int end = offset + length;
 
@@ -1026,10 +1076,11 @@ static <T> UnmodifiableListIterator<T> forArray(
     if (length == 0) {
       return emptyListIterator();
     }
-    return new ArrayItr<T>(array, offset, length, index);
+    return new ArrayItr<>(array, offset, length, index);
   }
 
-  private static final class ArrayItr<T> extends AbstractIndexedListIterator<T> {
+  private static final class ArrayItr<T extends @Nullable Object>
+      extends AbstractIndexedListIterator<T> {
     static final UnmodifiableListIterator<Object> EMPTY = new ArrayItr<>(new Object[0], 0, 0, 0);
 
     private final T[] array;
@@ -1042,6 +1093,7 @@ private static final class ArrayItr<T> extends AbstractIndexedListIterator<T> {
     }
 
     @Override
+    @ParametricNullness
     protected T get(int index) {
       return array[offset + index];
     }
@@ -1052,7 +1104,8 @@ protected T get(int index) {
    *
    * <p>The {@link Iterable} equivalent of this method is {@link Collections#singleton}.
    */
-  public static <T> UnmodifiableIterator<T> singletonIterator(@NullableDecl final T value) {
+  public static <T extends @Nullable Object> UnmodifiableIterator<T> singletonIterator(
+      @ParametricNullness T value) {
     return new UnmodifiableIterator<T>() {
       boolean done;
 
@@ -1062,6 +1115,7 @@ public boolean hasNext() {
       }
 
       @Override
+      @ParametricNullness
       public T next() {
         if (done) {
           throw new NoSuchElementException();
@@ -1082,7 +1136,8 @@ public T next() {
    * <p><b>Java 9 users:</b> use {@code enumeration.asIterator()} instead, unless it is important to
    * return an {@code UnmodifiableIterator} instead of a plain {@code Iterator}.
    */
-  public static <T> UnmodifiableIterator<T> forEnumeration(final Enumeration<T> enumeration) {
+  public static <T extends @Nullable Object> UnmodifiableIterator<T> forEnumeration(
+      Enumeration<T> enumeration) {
     checkNotNull(enumeration);
     return new UnmodifiableIterator<T>() {
       @Override
@@ -1091,6 +1146,7 @@ public boolean hasNext() {
       }
 
       @Override
+      @ParametricNullness
       public T next() {
         return enumeration.nextElement();
       }
@@ -1103,7 +1159,7 @@ public T next() {
    * <p>The {@code Iterable} equivalent of this method is either {@link Collections#enumeration} (if
    * you have a {@link Collection}), or {@code Iterators.asEnumeration(collection.iterator())}.
    */
-  public static <T> Enumeration<T> asEnumeration(final Iterator<T> iterator) {
+  public static <T extends @Nullable Object> Enumeration<T> asEnumeration(Iterator<T> iterator) {
     checkNotNull(iterator);
     return new Enumeration<T>() {
       @Override
@@ -1112,6 +1168,7 @@ public boolean hasMoreElements() {
       }
 
       @Override
+      @ParametricNullness
       public T nextElement() {
         return iterator.next();
       }
@@ -1119,11 +1176,11 @@ public T nextElement() {
   }
 
   /** Implementation of PeekingIterator that avoids peeking unless necessary. */
-  private static class PeekingImpl<E> implements PeekingIterator<E> {
+  private static class PeekingImpl<E extends @Nullable Object> implements PeekingIterator<E> {
 
     private final Iterator<? extends E> iterator;
     private boolean hasPeeked;
-    @NullableDecl private E peekedElement;
+    @CheckForNull private E peekedElement;
 
     public PeekingImpl(Iterator<? extends E> iterator) {
       this.iterator = checkNotNull(iterator);
@@ -1135,11 +1192,13 @@ public boolean hasNext() {
     }
 
     @Override
+    @ParametricNullness
     public E next() {
       if (!hasPeeked) {
         return iterator.next();
       }
-      E result = peekedElement;
+      // The cast is safe because of the hasPeeked check.
+      E result = uncheckedCastNullableTToT(peekedElement);
       hasPeeked = false;
       peekedElement = null;
       return result;
@@ -1152,12 +1211,14 @@ public void remove() {
     }
 
     @Override
+    @ParametricNullness
     public E peek() {
       if (!hasPeeked) {
         peekedElement = iterator.next();
         hasPeeked = true;
       }
-      return peekedElement;
+      // The cast is safe because of the hasPeeked check.
+      return uncheckedCastNullableTToT(peekedElement);
     }
   }
 
@@ -1197,7 +1258,8 @@ public E peek() {
    * @return a peeking iterator backed by that iterator. Apart from the additional {@link
    *     PeekingIterator#peek()} method, this iterator behaves exactly the same as {@code iterator}.
    */
-  public static <T> PeekingIterator<T> peekingIterator(Iterator<? extends T> iterator) {
+  public static <T extends @Nullable Object> PeekingIterator<T> peekingIterator(
+      Iterator<? extends T> iterator) {
     if (iterator instanceof PeekingImpl) {
       // Safe to cast <? extends T> to <T> because PeekingImpl only uses T
       // covariantly (and cannot be subclassed to add non-covariant uses).
@@ -1205,7 +1267,7 @@ public static <T> PeekingIterator<T> peekingIterator(Iterator<? extends T> itera
       PeekingImpl<T> peeking = (PeekingImpl<T>) iterator;
       return peeking;
     }
-    return new PeekingImpl<T>(iterator);
+    return new PeekingImpl<>(iterator);
   }
 
   /**
@@ -1215,7 +1277,8 @@ public static <T> PeekingIterator<T> peekingIterator(Iterator<? extends T> itera
    * @since 10.0
    */
   @Deprecated
-  public static <T> PeekingIterator<T> peekingIterator(PeekingIterator<T> iterator) {
+  public static <T extends @Nullable Object> PeekingIterator<T> peekingIterator(
+      PeekingIterator<T> iterator) {
     return checkNotNull(iterator);
   }
 
@@ -1232,12 +1295,12 @@ public static <T> PeekingIterator<T> peekingIterator(PeekingIterator<T> iterator
    * @since 11.0
    */
   @Beta
-  public static <T> UnmodifiableIterator<T> mergeSorted(
+  public static <T extends @Nullable Object> UnmodifiableIterator<T> mergeSorted(
       Iterable<? extends Iterator<? extends T>> iterators, Comparator<? super T> comparator) {
     checkNotNull(iterators, "iterators");
     checkNotNull(comparator, "comparator");
 
-    return new MergingIterator<T>(iterators, comparator);
+    return new MergingIterator<>(iterators, comparator);
   }
 
   /**
@@ -1249,21 +1312,16 @@ public static <T> UnmodifiableIterator<T> mergeSorted(
    * iterators. (Retrieving all elements takes approximately O(N*log(M)) time, where N is the total
    * number of elements.)
    */
-  private static class MergingIterator<T> extends UnmodifiableIterator<T> {
+  private static class MergingIterator<T extends @Nullable Object> extends UnmodifiableIterator<T> {
     final Queue<PeekingIterator<T>> queue;
 
     public MergingIterator(
-        Iterable<? extends Iterator<? extends T>> iterators,
-        final Comparator<? super T> itemComparator) {
+        Iterable<? extends Iterator<? extends T>> iterators, Comparator<? super T> itemComparator) {
       // A comparator that's used by the heap, allowing the heap
       // to be sorted based on the top of each iterator.
       Comparator<PeekingIterator<T>> heapComparator =
-          new Comparator<PeekingIterator<T>>() {
-            @Override
-            public int compare(PeekingIterator<T> o1, PeekingIterator<T> o2) {
-              return itemComparator.compare(o1.peek(), o2.peek());
-            }
-          };
+          (PeekingIterator<T> o1, PeekingIterator<T> o2) ->
+              itemComparator.compare(o1.peek(), o2.peek());
 
       queue = new PriorityQueue<>(2, heapComparator);
 
@@ -1280,6 +1338,7 @@ public boolean hasNext() {
     }
 
     @Override
+    @ParametricNullness
     public T next() {
       PeekingIterator<T> nextIter = queue.remove();
       T next = nextIter.next();
@@ -1290,9 +1349,9 @@ public T next() {
     }
   }
 
-  private static class ConcatenatedIterator<T> implements Iterator<T> {
+  private static class ConcatenatedIterator<T extends @Nullable Object> implements Iterator<T> {
     /* The last iterator to return an element.  Calls to remove() go to this iterator. */
-    @NullableDecl private Iterator<? extends T> toRemove;
+    @CheckForNull private Iterator<? extends T> toRemove;
 
     /* The iterator currently returning elements. */
     private Iterator<? extends T> iterator;
@@ -1304,10 +1363,10 @@ private static class ConcatenatedIterator<T> implements Iterator<T> {
      * operation O(1).
      */
 
-    private Iterator<? extends Iterator<? extends T>> topMetaIterator;
+    @CheckForNull private Iterator<? extends Iterator<? extends T>> topMetaIterator;
 
     // Only becomes nonnull if we encounter nested concatenations.
-    @NullableDecl private Deque<Iterator<? extends Iterator<? extends T>>> metaIterators;
+    @CheckForNull private Deque<Iterator<? extends Iterator<? extends T>>> metaIterators;
 
     ConcatenatedIterator(Iterator<? extends Iterator<? extends T>> metaIterator) {
       iterator = emptyIterator();
@@ -1315,7 +1374,7 @@ private static class ConcatenatedIterator<T> implements Iterator<T> {
     }
 
     // Returns a nonempty meta-iterator or, if all meta-iterators are empty, null.
-    @NullableDecl
+    @CheckForNull
     private Iterator<? extends Iterator<? extends T>> getTopMetaIterator() {
       while (topMetaIterator == null || !topMetaIterator.hasNext()) {
         if (metaIterators != null && !metaIterators.isEmpty()) {
@@ -1366,6 +1425,7 @@ public boolean hasNext() {
     }
 
     @Override
+    @ParametricNullness
     public T next() {
       if (hasNext()) {
         toRemove = iterator;
@@ -1377,14 +1437,16 @@ public T next() {
 
     @Override
     public void remove() {
-      CollectPreconditions.checkRemove(toRemove != null);
+      if (toRemove == null) {
+        throw new IllegalStateException("no calls to next() since the last call to remove()");
+      }
       toRemove.remove();
       toRemove = null;
     }
   }
 
   /** Used to avoid http://bugs.sun.com/view_bug.do?bug_id=6558557 */
-  static <T> ListIterator<T> cast(Iterator<T> iterator) {
+  static <T extends @Nullable Object> ListIterator<T> cast(Iterator<T> iterator) {
     return (ListIterator<T>) iterator;
   }
 }
diff --git a/android/guava/src/com/google/common/collect/LexicographicalOrdering.java b/android/guava/src/com/google/common/collect/LexicographicalOrdering.java
index 0e6c19652abf..91fc7bf7241c 100644
--- a/android/guava/src/com/google/common/collect/LexicographicalOrdering.java
+++ b/android/guava/src/com/google/common/collect/LexicographicalOrdering.java
@@ -20,11 +20,14 @@
 import java.io.Serializable;
 import java.util.Comparator;
 import java.util.Iterator;
-import org.checkerframework.checker.nullness.compatqual.NullableDecl;
+import javax.annotation.CheckForNull;
+import org.checkerframework.checker.nullness.qual.Nullable;
 
 /** An ordering which sorts iterables by comparing corresponding elements pairwise. */
 @GwtCompatible(serializable = true)
-final class LexicographicalOrdering<T> extends Ordering<Iterable<T>> implements Serializable {
+@ElementTypesAreNonnullByDefault
+final class LexicographicalOrdering<T extends @Nullable Object> extends Ordering<Iterable<T>>
+    implements Serializable {
   final Comparator<? super T> elementOrder;
 
   LexicographicalOrdering(Comparator<? super T> elementOrder) {
@@ -51,7 +54,7 @@ public int compare(Iterable<T> leftIterable, Iterable<T> rightIterable) {
   }
 
   @Override
-  public boolean equals(@NullableDecl Object object) {
+  public boolean equals(@CheckForNull Object object) {
     if (object == this) {
       return true;
     }
diff --git a/android/guava/src/com/google/common/collect/LinkedHashMultimap.java b/android/guava/src/com/google/common/collect/LinkedHashMultimap.java
index 361661705d55..11cddc383749 100644
--- a/android/guava/src/com/google/common/collect/LinkedHashMultimap.java
+++ b/android/guava/src/com/google/common/collect/LinkedHashMultimap.java
@@ -16,8 +16,9 @@
 
 package com.google.common.collect;
 
+import static com.google.common.base.Preconditions.checkState;
 import static com.google.common.collect.CollectPreconditions.checkNonnegative;
-import static com.google.common.collect.CollectPreconditions.checkRemove;
+import static java.util.Objects.requireNonNull;
 
 import com.google.common.annotations.GwtCompatible;
 import com.google.common.annotations.GwtIncompatible;
@@ -36,7 +37,8 @@
 import java.util.Map.Entry;
 import java.util.NoSuchElementException;
 import java.util.Set;
-import org.checkerframework.checker.nullness.compatqual.NullableDecl;
+import javax.annotation.CheckForNull;
+import org.checkerframework.checker.nullness.qual.Nullable;
 
 /**
  * Implementation of {@code Multimap} that does not allow duplicate key-value entries and that
@@ -65,20 +67,25 @@
  * read operations will work correctly. To allow concurrent update operations, wrap your multimap
  * with a call to {@link Multimaps#synchronizedSetMultimap}.
  *
+ * <p><b>Warning:</b> Do not modify either a key <i>or a value</i> of a {@code LinkedHashMultimap}
+ * in a way that affects its {@link Object#equals} behavior. Undefined behavior and bugs will
+ * result.
+ *
  * <p>See the Guava User Guide article on <a href=
- * "https://github.com/google/guava/wiki/NewCollectionTypesExplained#multimap"> {@code
- * Multimap}</a>.
+ * "https://github.com/google/guava/wiki/NewCollectionTypesExplained#multimap">{@code Multimap}</a>.
  *
  * @author Jared Levy
  * @author Louis Wasserman
  * @since 2.0
  */
 @GwtCompatible(serializable = true, emulated = true)
-public final class LinkedHashMultimap<K, V>
+@ElementTypesAreNonnullByDefault
+public final class LinkedHashMultimap<K extends @Nullable Object, V extends @Nullable Object>
     extends LinkedHashMultimapGwtSerializationDependencies<K, V> {
 
   /** Creates a new, empty {@code LinkedHashMultimap} with the default initial capacities. */
-  public static <K, V> LinkedHashMultimap<K, V> create() {
+  public static <K extends @Nullable Object, V extends @Nullable Object>
+      LinkedHashMultimap<K, V> create() {
     return new LinkedHashMultimap<>(DEFAULT_KEY_CAPACITY, DEFAULT_VALUE_SET_CAPACITY);
   }
 
@@ -91,7 +98,8 @@ public static <K, V> LinkedHashMultimap<K, V> create() {
    * @throws IllegalArgumentException if {@code expectedKeys} or {@code expectedValuesPerKey} is
    *     negative
    */
-  public static <K, V> LinkedHashMultimap<K, V> create(int expectedKeys, int expectedValuesPerKey) {
+  public static <K extends @Nullable Object, V extends @Nullable Object>
+      LinkedHashMultimap<K, V> create(int expectedKeys, int expectedValuesPerKey) {
     return new LinkedHashMultimap<>(
         Maps.capacity(expectedKeys), Maps.capacity(expectedValuesPerKey));
   }
@@ -104,14 +112,14 @@ public static <K, V> LinkedHashMultimap<K, V> create(int expectedKeys, int expec
    *
    * @param multimap the multimap whose contents are copied to this multimap
    */
-  public static <K, V> LinkedHashMultimap<K, V> create(
-      Multimap<? extends K, ? extends V> multimap) {
+  public static <K extends @Nullable Object, V extends @Nullable Object>
+      LinkedHashMultimap<K, V> create(Multimap<? extends K, ? extends V> multimap) {
     LinkedHashMultimap<K, V> result = create(multimap.keySet().size(), DEFAULT_VALUE_SET_CAPACITY);
     result.putAll(multimap);
     return result;
   }
 
-  private interface ValueSetLink<K, V> {
+  private interface ValueSetLink<K extends @Nullable Object, V extends @Nullable Object> {
     ValueSetLink<K, V> getPredecessorInValueSet();
 
     ValueSetLink<K, V> getSuccessorInValueSet();
@@ -121,21 +129,25 @@ private interface ValueSetLink<K, V> {
     void setSuccessorInValueSet(ValueSetLink<K, V> entry);
   }
 
-  private static <K, V> void succeedsInValueSet(ValueSetLink<K, V> pred, ValueSetLink<K, V> succ) {
+  private static <K extends @Nullable Object, V extends @Nullable Object> void succeedsInValueSet(
+      ValueSetLink<K, V> pred, ValueSetLink<K, V> succ) {
     pred.setSuccessorInValueSet(succ);
     succ.setPredecessorInValueSet(pred);
   }
 
-  private static <K, V> void succeedsInMultimap(ValueEntry<K, V> pred, ValueEntry<K, V> succ) {
+  private static <K extends @Nullable Object, V extends @Nullable Object> void succeedsInMultimap(
+      ValueEntry<K, V> pred, ValueEntry<K, V> succ) {
     pred.setSuccessorInMultimap(succ);
     succ.setPredecessorInMultimap(pred);
   }
 
-  private static <K, V> void deleteFromValueSet(ValueSetLink<K, V> entry) {
+  private static <K extends @Nullable Object, V extends @Nullable Object> void deleteFromValueSet(
+      ValueSetLink<K, V> entry) {
     succeedsInValueSet(entry.getPredecessorInValueSet(), entry.getSuccessorInValueSet());
   }
 
-  private static <K, V> void deleteFromMultimap(ValueEntry<K, V> entry) {
+  private static <K extends @Nullable Object, V extends @Nullable Object> void deleteFromMultimap(
+      ValueEntry<K, V> entry) {
     succeedsInMultimap(entry.getPredecessorInMultimap(), entry.getSuccessorInMultimap());
   }
 
@@ -146,39 +158,69 @@ private static <K, V> void deleteFromMultimap(ValueEntry<K, V> entry) {
    * whole.
    */
   @VisibleForTesting
-  static final class ValueEntry<K, V> extends ImmutableEntry<K, V> implements ValueSetLink<K, V> {
+  static final class ValueEntry<K extends @Nullable Object, V extends @Nullable Object>
+      extends ImmutableEntry<K, V> implements ValueSetLink<K, V> {
     final int smearedValueHash;
 
-    @NullableDecl ValueEntry<K, V> nextInValueBucket;
+    @CheckForNull ValueEntry<K, V> nextInValueBucket;
+    /*
+     * The *InValueSet and *InMultimap fields below are null after construction, but we almost
+     * always call succeedsIn*() to initialize them immediately thereafter.
+     *
+     * The exception is the *InValueSet fields of multimapHeaderEntry, which are never set. (That
+     * works out fine as long as we continue to be careful not to try delete them or iterate past
+     * them.)
+     *
+     * We could consider "lying" and omitting @CheckNotNull from all these fields. Normally, I'm not
+     * a fan of that: What if we someday implement (presumably to be enabled during tests only)
+     * bytecode rewriting that checks for any null value that passes through an API with a
+     * known-non-null type? But that particular problem might not arise here, since we're not
+     * actually reading from the fields in any case in which they might be null (as proven by the
+     * requireNonNull checks below). Plus, we're *already* lying here, since newHeader passes a null
+     * key and value, which we pass to the superconstructor, even though the key and value type for
+     * a given entry might not include null. The right fix for the header problems is probably to
+     * define a separate MultimapLink interface with a separate "header" implementation, which
+     * hopefully could avoid implementing Entry or ValueSetLink at all. (But note that that approach
+     * requires us to define extra classes -- unfortunate under Android.) *Then* we could consider
+     * lying about the fields below on the grounds that we always initialize them just after the
+     * constructor -- an example of the kind of lying that our hypotheticaly bytecode rewriter would
+     * already have to deal with, thanks to DI frameworks that perform field and method injection,
+     * frameworks like Android that define post-construct hooks like Activity.onCreate, etc.
+     */
 
-    @NullableDecl ValueSetLink<K, V> predecessorInValueSet;
-    @NullableDecl ValueSetLink<K, V> successorInValueSet;
+    @CheckForNull ValueSetLink<K, V> predecessorInValueSet;
+    @CheckForNull ValueSetLink<K, V> successorInValueSet;
 
-    @NullableDecl ValueEntry<K, V> predecessorInMultimap;
-    @NullableDecl ValueEntry<K, V> successorInMultimap;
+    @CheckForNull ValueEntry<K, V> predecessorInMultimap;
+    @CheckForNull ValueEntry<K, V> successorInMultimap;
 
     ValueEntry(
-        @NullableDecl K key,
-        @NullableDecl V value,
+        @ParametricNullness K key,
+        @ParametricNullness V value,
         int smearedValueHash,
-        @NullableDecl ValueEntry<K, V> nextInValueBucket) {
+        @CheckForNull ValueEntry<K, V> nextInValueBucket) {
       super(key, value);
       this.smearedValueHash = smearedValueHash;
       this.nextInValueBucket = nextInValueBucket;
     }
 
-    boolean matchesValue(@NullableDecl Object v, int smearedVHash) {
+    @SuppressWarnings("nullness") // see the comment on the class fields, especially about newHeader
+    static <K extends @Nullable Object, V extends @Nullable Object> ValueEntry<K, V> newHeader() {
+      return new ValueEntry<>(null, null, 0, null);
+    }
+
+    boolean matchesValue(@CheckForNull Object v, int smearedVHash) {
       return smearedValueHash == smearedVHash && Objects.equal(getValue(), v);
     }
 
     @Override
     public ValueSetLink<K, V> getPredecessorInValueSet() {
-      return predecessorInValueSet;
+      return requireNonNull(predecessorInValueSet); // see the comment on the class fields
     }
 
     @Override
     public ValueSetLink<K, V> getSuccessorInValueSet() {
-      return successorInValueSet;
+      return requireNonNull(successorInValueSet); // see the comment on the class fields
     }
 
     @Override
@@ -192,11 +234,11 @@ public void setSuccessorInValueSet(ValueSetLink<K, V> entry) {
     }
 
     public ValueEntry<K, V> getPredecessorInMultimap() {
-      return predecessorInMultimap;
+      return requireNonNull(predecessorInMultimap); // see the comment on the class fields
     }
 
     public ValueEntry<K, V> getSuccessorInMultimap() {
-      return successorInMultimap;
+      return requireNonNull(successorInMultimap); // see the comment on the class fields
     }
 
     public void setSuccessorInMultimap(ValueEntry<K, V> multimapSuccessor) {
@@ -220,7 +262,7 @@ private LinkedHashMultimap(int keyCapacity, int valueSetCapacity) {
     checkNonnegative(valueSetCapacity, "expectedValuesPerKey");
 
     this.valueSetCapacity = valueSetCapacity;
-    this.multimapHeaderEntry = new ValueEntry<>(null, null, 0, null);
+    this.multimapHeaderEntry = ValueEntry.newHeader();
     succeedsInMultimap(multimapHeaderEntry, multimapHeaderEntry);
   }
 
@@ -246,7 +288,7 @@ Set<V> createCollection() {
    * @return a new decorated set containing a collection of values for one key
    */
   @Override
-  Collection<V> createCollection(K key) {
+  Collection<V> createCollection(@ParametricNullness K key) {
     return new ValueSet(key, valueSetCapacity);
   }
 
@@ -259,7 +301,7 @@ Collection<V> createCollection(K key) {
    */
   @CanIgnoreReturnValue
   @Override
-  public Set<V> replaceValues(@NullableDecl K key, Iterable<? extends V> values) {
+  public Set<V> replaceValues(@ParametricNullness K key, Iterable<? extends V> values) {
     return super.replaceValues(key, values);
   }
 
@@ -314,8 +356,8 @@ final class ValueSet extends Sets.ImprovedAbstractSet<V> implements ValueSetLink
      * consumption.
      */
 
-    private final K key;
-    @VisibleForTesting ValueEntry<K, V>[] hashTable;
+    @ParametricNullness private final K key;
+    @VisibleForTesting @Nullable ValueEntry<K, V>[] hashTable;
     private int size = 0;
     private int modCount = 0;
 
@@ -324,15 +366,16 @@ final class ValueSet extends Sets.ImprovedAbstractSet<V> implements ValueSetLink
     private ValueSetLink<K, V> firstEntry;
     private ValueSetLink<K, V> lastEntry;
 
-    ValueSet(K key, int expectedValues) {
+    ValueSet(@ParametricNullness K key, int expectedValues) {
       this.key = key;
       this.firstEntry = this;
       this.lastEntry = this;
       // Round expected values up to a power of 2 to get the table size.
       int tableSize = Hashing.closedTableSize(expectedValues, VALUE_SET_LOAD_FACTOR);
 
-      @SuppressWarnings("unchecked")
-      ValueEntry<K, V>[] hashTable = new ValueEntry[tableSize];
+      @SuppressWarnings({"rawtypes", "unchecked"})
+      @Nullable
+      ValueEntry<K, V>[] hashTable = new @Nullable ValueEntry[tableSize];
       this.hashTable = hashTable;
     }
 
@@ -364,7 +407,7 @@ public void setSuccessorInValueSet(ValueSetLink<K, V> entry) {
     public Iterator<V> iterator() {
       return new Iterator<V>() {
         ValueSetLink<K, V> nextEntry = firstEntry;
-        @NullableDecl ValueEntry<K, V> toRemove;
+        @CheckForNull ValueEntry<K, V> toRemove;
         int expectedModCount = modCount;
 
         private void checkForComodification() {
@@ -380,6 +423,7 @@ public boolean hasNext() {
         }
 
         @Override
+        @ParametricNullness
         public V next() {
           if (!hasNext()) {
             throw new NoSuchElementException();
@@ -394,7 +438,7 @@ public V next() {
         @Override
         public void remove() {
           checkForComodification();
-          checkRemove(toRemove != null);
+          checkState(toRemove != null, "no calls to next() since the last call to remove()");
           ValueSet.this.remove(toRemove.getValue());
           expectedModCount = modCount;
           toRemove = null;
@@ -408,7 +452,7 @@ public int size() {
     }
 
     @Override
-    public boolean contains(@NullableDecl Object o) {
+    public boolean contains(@CheckForNull Object o) {
       int smearedHash = Hashing.smearedHash(o);
       for (ValueEntry<K, V> entry = hashTable[smearedHash & mask()];
           entry != null;
@@ -421,7 +465,7 @@ public boolean contains(@NullableDecl Object o) {
     }
 
     @Override
-    public boolean add(@NullableDecl V value) {
+    public boolean add(@ParametricNullness V value) {
       int smearedHash = Hashing.smearedHash(value);
       int bucket = smearedHash & mask();
       ValueEntry<K, V> rowHead = hashTable[bucket];
@@ -462,7 +506,7 @@ private void rehashIfNecessary() {
 
     @CanIgnoreReturnValue
     @Override
-    public boolean remove(@NullableDecl Object o) {
+    public boolean remove(@CheckForNull Object o) {
       int smearedHash = Hashing.smearedHash(o);
       int bucket = smearedHash & mask();
       ValueEntry<K, V> prev = null;
@@ -504,8 +548,8 @@ public void clear() {
   @Override
   Iterator<Entry<K, V>> entryIterator() {
     return new Iterator<Entry<K, V>>() {
-      ValueEntry<K, V> nextEntry = multimapHeaderEntry.successorInMultimap;
-      @NullableDecl ValueEntry<K, V> toRemove;
+      ValueEntry<K, V> nextEntry = multimapHeaderEntry.getSuccessorInMultimap();
+      @CheckForNull ValueEntry<K, V> toRemove;
 
       @Override
       public boolean hasNext() {
@@ -519,13 +563,13 @@ public Entry<K, V> next() {
         }
         ValueEntry<K, V> result = nextEntry;
         toRemove = result;
-        nextEntry = nextEntry.successorInMultimap;
+        nextEntry = nextEntry.getSuccessorInMultimap();
         return result;
       }
 
       @Override
       public void remove() {
-        checkRemove(toRemove != null);
+        checkState(toRemove != null, "no calls to next() since the last call to remove()");
         LinkedHashMultimap.this.remove(toRemove.getKey(), toRemove.getValue());
         toRemove = null;
       }
@@ -564,7 +608,7 @@ private void writeObject(ObjectOutputStream stream) throws IOException {
   @GwtIncompatible // java.io.ObjectInputStream
   private void readObject(ObjectInputStream stream) throws IOException, ClassNotFoundException {
     stream.defaultReadObject();
-    multimapHeaderEntry = new ValueEntry<>(null, null, 0, null);
+    multimapHeaderEntry = ValueEntry.newHeader();
     succeedsInMultimap(multimapHeaderEntry, multimapHeaderEntry);
     valueSetCapacity = DEFAULT_VALUE_SET_CAPACITY;
     int distinctKeys = stream.readInt();
@@ -580,7 +624,11 @@ private void readObject(ObjectInputStream stream) throws IOException, ClassNotFo
       K key = (K) stream.readObject();
       @SuppressWarnings("unchecked")
       V value = (V) stream.readObject();
-      map.get(key).add(value);
+      /*
+       * requireNonNull is safe for a properly serialized multimap: We've already inserted a
+       * collection for each key that we expect.
+       */
+      requireNonNull(map.get(key)).add(value);
     }
     setMap(map);
   }
diff --git a/android/guava/src/com/google/common/collect/LinkedHashMultiset.java b/android/guava/src/com/google/common/collect/LinkedHashMultiset.java
index 6f95d4d2dc4f..97595a9e0dde 100644
--- a/android/guava/src/com/google/common/collect/LinkedHashMultiset.java
+++ b/android/guava/src/com/google/common/collect/LinkedHashMultiset.java
@@ -17,6 +17,7 @@
 package com.google.common.collect;
 
 import com.google.common.annotations.GwtCompatible;
+import org.checkerframework.checker.nullness.qual.Nullable;
 
 /**
  * A {@code Multiset} implementation with predictable iteration order. Its iterator orders elements
@@ -26,18 +27,19 @@
  * element will appear at the end of the iteration.
  *
  * <p>See the Guava User Guide article on <a href=
- * "https://github.com/google/guava/wiki/NewCollectionTypesExplained#multiset"> {@code
- * Multiset}</a>.
+ * "https://github.com/google/guava/wiki/NewCollectionTypesExplained#multiset">{@code Multiset}</a>.
  *
  * @author Kevin Bourrillion
  * @author Jared Levy
  * @since 2.0
  */
 @GwtCompatible(serializable = true, emulated = true)
-public final class LinkedHashMultiset<E> extends AbstractMapBasedMultiset<E> {
+@ElementTypesAreNonnullByDefault
+public final class LinkedHashMultiset<E extends @Nullable Object>
+    extends AbstractMapBasedMultiset<E> {
 
   /** Creates a new, empty {@code LinkedHashMultiset} using the default initial capacity. */
-  public static <E> LinkedHashMultiset<E> create() {
+  public static <E extends @Nullable Object> LinkedHashMultiset<E> create() {
     return create(ObjectCountHashMap.DEFAULT_SIZE);
   }
 
@@ -48,7 +50,7 @@ public static <E> LinkedHashMultiset<E> create() {
    * @param distinctElements the expected number of distinct elements
    * @throws IllegalArgumentException if {@code distinctElements} is negative
    */
-  public static <E> LinkedHashMultiset<E> create(int distinctElements) {
+  public static <E extends @Nullable Object> LinkedHashMultiset<E> create(int distinctElements) {
     return new LinkedHashMultiset<E>(distinctElements);
   }
 
@@ -59,7 +61,8 @@ public static <E> LinkedHashMultiset<E> create(int distinctElements) {
    *
    * @param elements the elements that the multiset should contain
    */
-  public static <E> LinkedHashMultiset<E> create(Iterable<? extends E> elements) {
+  public static <E extends @Nullable Object> LinkedHashMultiset<E> create(
+      Iterable<? extends E> elements) {
     LinkedHashMultiset<E> multiset = create(Multisets.inferDistinctElements(elements));
     Iterables.addAll(multiset, elements);
     return multiset;
@@ -70,7 +73,7 @@ public static <E> LinkedHashMultiset<E> create(Iterable<? extends E> elements) {
   }
 
   @Override
-  void init(int distinctElements) {
-    backingMap = new ObjectCountLinkedHashMap<>(distinctElements);
+  ObjectCountHashMap<E> newBackingMap(int distinctElements) {
+    return new ObjectCountLinkedHashMap<>(distinctElements);
   }
 }
diff --git a/android/guava/src/com/google/common/collect/LinkedListMultimap.java b/android/guava/src/com/google/common/collect/LinkedListMultimap.java
index 3aa1efdabe36..338c5474246e 100644
--- a/android/guava/src/com/google/common/collect/LinkedListMultimap.java
+++ b/android/guava/src/com/google/common/collect/LinkedListMultimap.java
@@ -18,8 +18,8 @@
 
 import static com.google.common.base.Preconditions.checkPositionIndex;
 import static com.google.common.base.Preconditions.checkState;
-import static com.google.common.collect.CollectPreconditions.checkRemove;
 import static java.util.Collections.unmodifiableList;
+import static java.util.Objects.requireNonNull;
 
 import com.google.common.annotations.GwtCompatible;
 import com.google.common.annotations.GwtIncompatible;
@@ -39,7 +39,8 @@
 import java.util.Map.Entry;
 import java.util.NoSuchElementException;
 import java.util.Set;
-import org.checkerframework.checker.nullness.compatqual.NullableDecl;
+import javax.annotation.CheckForNull;
+import org.checkerframework.checker.nullness.qual.Nullable;
 
 /**
  * An implementation of {@code ListMultimap} that supports deterministic iteration order for both
@@ -87,15 +88,15 @@
  * with a call to {@link Multimaps#synchronizedListMultimap}.
  *
  * <p>See the Guava User Guide article on <a href=
- * "https://github.com/google/guava/wiki/NewCollectionTypesExplained#multimap"> {@code
- * Multimap}</a>.
+ * "https://github.com/google/guava/wiki/NewCollectionTypesExplained#multimap">{@code Multimap}</a>.
  *
  * @author Mike Bostock
  * @since 2.0
  */
 @GwtCompatible(serializable = true, emulated = true)
-public class LinkedListMultimap<K, V> extends AbstractMultimap<K, V>
-    implements ListMultimap<K, V>, Serializable {
+@ElementTypesAreNonnullByDefault
+public class LinkedListMultimap<K extends @Nullable Object, V extends @Nullable Object>
+    extends AbstractMultimap<K, V> implements ListMultimap<K, V>, Serializable {
   /*
    * Order is maintained using a linked list containing all key-value pairs. In
    * addition, a series of disjoint linked lists of "siblings", each containing
@@ -103,38 +104,42 @@ public class LinkedListMultimap<K, V> extends AbstractMultimap<K, V>
    * ValueForKeyIterator} in constant time.
    */
 
-  private static final class Node<K, V> extends AbstractMapEntry<K, V> {
-    @NullableDecl final K key;
-    @NullableDecl V value;
-    @NullableDecl Node<K, V> next; // the next node (with any key)
-    @NullableDecl Node<K, V> previous; // the previous node (with any key)
-    @NullableDecl Node<K, V> nextSibling; // the next node with the same key
-    @NullableDecl Node<K, V> previousSibling; // the previous node with the same key
+  private static final class Node<K extends @Nullable Object, V extends @Nullable Object>
+      extends AbstractMapEntry<K, V> {
+    @ParametricNullness final K key;
+    @ParametricNullness V value;
+    @CheckForNull Node<K, V> next; // the next node (with any key)
+    @CheckForNull Node<K, V> previous; // the previous node (with any key)
+    @CheckForNull Node<K, V> nextSibling; // the next node with the same key
+    @CheckForNull Node<K, V> previousSibling; // the previous node with the same key
 
-    Node(@NullableDecl K key, @NullableDecl V value) {
+    Node(@ParametricNullness K key, @ParametricNullness V value) {
       this.key = key;
       this.value = value;
     }
 
     @Override
+    @ParametricNullness
     public K getKey() {
       return key;
     }
 
     @Override
+    @ParametricNullness
     public V getValue() {
       return value;
     }
 
     @Override
-    public V setValue(@NullableDecl V newValue) {
+    @ParametricNullness
+    public V setValue(@ParametricNullness V newValue) {
       V result = value;
       this.value = newValue;
       return result;
     }
   }
 
-  private static class KeyList<K, V> {
+  private static class KeyList<K extends @Nullable Object, V extends @Nullable Object> {
     Node<K, V> head;
     Node<K, V> tail;
     int count;
@@ -148,8 +153,8 @@ private static class KeyList<K, V> {
     }
   }
 
-  @NullableDecl private transient Node<K, V> head; // the head for all keys
-  @NullableDecl private transient Node<K, V> tail; // the tail for all keys
+  @CheckForNull private transient Node<K, V> head; // the head for all keys
+  @CheckForNull private transient Node<K, V> tail; // the tail for all keys
   private transient Map<K, KeyList<K, V>> keyToKeyList;
   private transient int size;
 
@@ -161,7 +166,8 @@ private static class KeyList<K, V> {
   private transient int modCount;
 
   /** Creates a new, empty {@code LinkedListMultimap} with the default initial capacity. */
-  public static <K, V> LinkedListMultimap<K, V> create() {
+  public static <K extends @Nullable Object, V extends @Nullable Object>
+      LinkedListMultimap<K, V> create() {
     return new LinkedListMultimap<>();
   }
 
@@ -172,7 +178,8 @@ public static <K, V> LinkedListMultimap<K, V> create() {
    * @param expectedKeys the expected number of distinct keys
    * @throws IllegalArgumentException if {@code expectedKeys} is negative
    */
-  public static <K, V> LinkedListMultimap<K, V> create(int expectedKeys) {
+  public static <K extends @Nullable Object, V extends @Nullable Object>
+      LinkedListMultimap<K, V> create(int expectedKeys) {
     return new LinkedListMultimap<>(expectedKeys);
   }
 
@@ -183,8 +190,8 @@ public static <K, V> LinkedListMultimap<K, V> create(int expectedKeys) {
    *
    * @param multimap the multimap whose contents are copied to this multimap
    */
-  public static <K, V> LinkedListMultimap<K, V> create(
-      Multimap<? extends K, ? extends V> multimap) {
+  public static <K extends @Nullable Object, V extends @Nullable Object>
+      LinkedListMultimap<K, V> create(Multimap<? extends K, ? extends V> multimap) {
     return new LinkedListMultimap<>(multimap);
   }
 
@@ -208,14 +215,17 @@ private LinkedListMultimap(Multimap<? extends K, ? extends V> multimap) {
    */
   @CanIgnoreReturnValue
   private Node<K, V> addNode(
-      @NullableDecl K key, @NullableDecl V value, @NullableDecl Node<K, V> nextSibling) {
+      @ParametricNullness K key,
+      @ParametricNullness V value,
+      @CheckForNull Node<K, V> nextSibling) {
     Node<K, V> node = new Node<>(key, value);
     if (head == null) { // empty list
       head = tail = node;
       keyToKeyList.put(key, new KeyList<K, V>(node));
       modCount++;
     } else if (nextSibling == null) { // non-empty list, add to tail
-      tail.next = node;
+      // requireNonNull is safe because the list is non-empty.
+      requireNonNull(tail).next = node;
       node.previous = tail;
       tail = node;
       KeyList<K, V> keyList = keyToKeyList.get(key);
@@ -230,14 +240,19 @@ private Node<K, V> addNode(
         keyList.tail = node;
       }
     } else { // non-empty list, insert before nextSibling
-      KeyList<K, V> keyList = keyToKeyList.get(key);
+      /*
+       * requireNonNull is safe as long as callers pass a nextSibling that (a) has the same key and
+       * (b) is present in the multimap. (And they do, except maybe in case of concurrent
+       * modification, in which case all bets are off.)
+       */
+      KeyList<K, V> keyList = requireNonNull(keyToKeyList.get(key));
       keyList.count++;
       node.previous = nextSibling.previous;
       node.previousSibling = nextSibling.previousSibling;
       node.next = nextSibling;
       node.nextSibling = nextSibling;
       if (nextSibling.previousSibling == null) { // nextSibling was key head
-        keyToKeyList.get(key).head = node;
+        keyList.head = node;
       } else {
         nextSibling.previousSibling.nextSibling = node;
       }
@@ -269,21 +284,29 @@ private void removeNode(Node<K, V> node) {
       tail = node.previous;
     }
     if (node.previousSibling == null && node.nextSibling == null) {
-      KeyList<K, V> keyList = keyToKeyList.remove(node.key);
+      /*
+       * requireNonNull is safe as long as we call removeNode only for nodes that are still in the
+       * Multimap. This should be the case (except in case of concurrent modification, when all bets
+       * are off).
+       */
+      KeyList<K, V> keyList = requireNonNull(keyToKeyList.remove(node.key));
       keyList.count = 0;
       modCount++;
     } else {
-      KeyList<K, V> keyList = keyToKeyList.get(node.key);
+      // requireNonNull is safe (under the conditions listed in the comment in the branch above).
+      KeyList<K, V> keyList = requireNonNull(keyToKeyList.get(node.key));
       keyList.count--;
 
       if (node.previousSibling == null) {
-        keyList.head = node.nextSibling;
+        // requireNonNull is safe because we checked that not *both* siblings were null.
+        keyList.head = requireNonNull(node.nextSibling);
       } else {
         node.previousSibling.nextSibling = node.nextSibling;
       }
 
       if (node.nextSibling == null) {
-        keyList.tail = node.previousSibling;
+        // requireNonNull is safe because we checked that not *both* siblings were null.
+        keyList.tail = requireNonNull(node.previousSibling);
       } else {
         node.nextSibling.previousSibling = node.previousSibling;
       }
@@ -292,23 +315,16 @@ private void removeNode(Node<K, V> node) {
   }
 
   /** Removes all nodes for the specified key. */
-  private void removeAllNodes(@NullableDecl Object key) {
+  private void removeAllNodes(@ParametricNullness K key) {
     Iterators.clear(new ValueForKeyIterator(key));
   }
 
-  /** Helper method for verifying that an iterator element is present. */
-  private static void checkElement(@NullableDecl Object node) {
-    if (node == null) {
-      throw new NoSuchElementException();
-    }
-  }
-
   /** An {@code Iterator} over all nodes. */
   private class NodeIterator implements ListIterator<Entry<K, V>> {
     int nextIndex;
-    @NullableDecl Node<K, V> next;
-    @NullableDecl Node<K, V> current;
-    @NullableDecl Node<K, V> previous;
+    @CheckForNull Node<K, V> next;
+    @CheckForNull Node<K, V> current;
+    @CheckForNull Node<K, V> previous;
     int expectedModCount = modCount;
 
     NodeIterator(int index) {
@@ -345,7 +361,9 @@ public boolean hasNext() {
     @Override
     public Node<K, V> next() {
       checkForConcurrentModification();
-      checkElement(next);
+      if (next == null) {
+        throw new NoSuchElementException();
+      }
       previous = current = next;
       next = next.next;
       nextIndex++;
@@ -355,7 +373,7 @@ public Node<K, V> next() {
     @Override
     public void remove() {
       checkForConcurrentModification();
-      checkRemove(current != null);
+      checkState(current != null, "no calls to next() since the last call to remove()");
       if (current != next) { // after call to next()
         previous = current.previous;
         nextIndex--;
@@ -377,7 +395,9 @@ public boolean hasPrevious() {
     @Override
     public Node<K, V> previous() {
       checkForConcurrentModification();
-      checkElement(previous);
+      if (previous == null) {
+        throw new NoSuchElementException();
+      }
       next = current = previous;
       previous = previous.previous;
       nextIndex--;
@@ -404,7 +424,7 @@ public void add(Entry<K, V> e) {
       throw new UnsupportedOperationException();
     }
 
-    void setValue(V value) {
+    void setValue(@ParametricNullness V value) {
       checkState(current != null);
       current.value = value;
     }
@@ -413,8 +433,8 @@ void setValue(V value) {
   /** An {@code Iterator} over distinct keys in key head order. */
   private class DistinctKeyIterator implements Iterator<K> {
     final Set<K> seenKeys = Sets.<K>newHashSetWithExpectedSize(keySet().size());
-    Node<K, V> next = head;
-    @NullableDecl Node<K, V> current;
+    @CheckForNull Node<K, V> next = head;
+    @CheckForNull Node<K, V> current;
     int expectedModCount = modCount;
 
     private void checkForConcurrentModification() {
@@ -430,9 +450,12 @@ public boolean hasNext() {
     }
 
     @Override
+    @ParametricNullness
     public K next() {
       checkForConcurrentModification();
-      checkElement(next);
+      if (next == null) {
+        throw new NoSuchElementException();
+      }
       current = next;
       seenKeys.add(current.key);
       do { // skip ahead to next unseen key
@@ -444,7 +467,7 @@ public K next() {
     @Override
     public void remove() {
       checkForConcurrentModification();
-      checkRemove(current != null);
+      checkState(current != null, "no calls to next() since the last call to remove()");
       removeAllNodes(current.key);
       current = null;
       expectedModCount = modCount;
@@ -453,14 +476,14 @@ public void remove() {
 
   /** A {@code ListIterator} over values for a specified key. */
   private class ValueForKeyIterator implements ListIterator<V> {
-    @NullableDecl final Object key;
+    @ParametricNullness final K key;
     int nextIndex;
-    @NullableDecl Node<K, V> next;
-    @NullableDecl Node<K, V> current;
-    @NullableDecl Node<K, V> previous;
+    @CheckForNull Node<K, V> next;
+    @CheckForNull Node<K, V> current;
+    @CheckForNull Node<K, V> previous;
 
     /** Constructs a new iterator over all values for the specified key. */
-    ValueForKeyIterator(@NullableDecl Object key) {
+    ValueForKeyIterator(@ParametricNullness K key) {
       this.key = key;
       KeyList<K, V> keyList = keyToKeyList.get(key);
       next = (keyList == null) ? null : keyList.head;
@@ -474,7 +497,7 @@ private class ValueForKeyIterator implements ListIterator<V> {
      *
      * @throws IndexOutOfBoundsException if index is invalid
      */
-    public ValueForKeyIterator(@NullableDecl Object key, int index) {
+    public ValueForKeyIterator(@ParametricNullness K key, int index) {
       KeyList<K, V> keyList = keyToKeyList.get(key);
       int size = (keyList == null) ? 0 : keyList.count;
       checkPositionIndex(index, size);
@@ -501,8 +524,11 @@ public boolean hasNext() {
 
     @CanIgnoreReturnValue
     @Override
+    @ParametricNullness
     public V next() {
-      checkElement(next);
+      if (next == null) {
+        throw new NoSuchElementException();
+      }
       previous = current = next;
       next = next.nextSibling;
       nextIndex++;
@@ -516,8 +542,11 @@ public boolean hasPrevious() {
 
     @CanIgnoreReturnValue
     @Override
+    @ParametricNullness
     public V previous() {
-      checkElement(previous);
+      if (previous == null) {
+        throw new NoSuchElementException();
+      }
       next = current = previous;
       previous = previous.previousSibling;
       nextIndex--;
@@ -536,7 +565,7 @@ public int previousIndex() {
 
     @Override
     public void remove() {
-      checkRemove(current != null);
+      checkState(current != null, "no calls to next() since the last call to remove()");
       if (current != next) { // after call to next()
         previous = current.previousSibling;
         nextIndex--;
@@ -548,15 +577,14 @@ public void remove() {
     }
 
     @Override
-    public void set(V value) {
+    public void set(@ParametricNullness V value) {
       checkState(current != null);
       current.value = value;
     }
 
     @Override
-    @SuppressWarnings("unchecked")
-    public void add(V value) {
-      previous = addNode((K) key, value, next);
+    public void add(@ParametricNullness V value) {
+      previous = addNode(key, value, next);
       nextIndex++;
       current = null;
     }
@@ -575,12 +603,12 @@ public boolean isEmpty() {
   }
 
   @Override
-  public boolean containsKey(@NullableDecl Object key) {
+  public boolean containsKey(@CheckForNull Object key) {
     return keyToKeyList.containsKey(key);
   }
 
   @Override
-  public boolean containsValue(@NullableDecl Object value) {
+  public boolean containsValue(@CheckForNull Object value) {
     return values().contains(value);
   }
 
@@ -595,7 +623,7 @@ public boolean containsValue(@NullableDecl Object value) {
    */
   @CanIgnoreReturnValue
   @Override
-  public boolean put(@NullableDecl K key, @NullableDecl V value) {
+  public boolean put(@ParametricNullness K key, @ParametricNullness V value) {
     addNode(key, value, null);
     return true;
   }
@@ -612,7 +640,7 @@ public boolean put(@NullableDecl K key, @NullableDecl V value) {
    */
   @CanIgnoreReturnValue
   @Override
-  public List<V> replaceValues(@NullableDecl K key, Iterable<? extends V> values) {
+  public List<V> replaceValues(@ParametricNullness K key, Iterable<? extends V> values) {
     List<V> oldValues = getCopy(key);
     ListIterator<V> keyValues = new ValueForKeyIterator(key);
     Iterator<? extends V> newValues = values.iterator();
@@ -637,7 +665,7 @@ public List<V> replaceValues(@NullableDecl K key, Iterable<? extends V> values)
     return oldValues;
   }
 
-  private List<V> getCopy(@NullableDecl Object key) {
+  private List<V> getCopy(@ParametricNullness K key) {
     return unmodifiableList(Lists.newArrayList(new ValueForKeyIterator(key)));
   }
 
@@ -648,9 +676,16 @@ private List<V> getCopy(@NullableDecl Object key) {
    */
   @CanIgnoreReturnValue
   @Override
-  public List<V> removeAll(@NullableDecl Object key) {
-    List<V> oldValues = getCopy(key);
-    removeAllNodes(key);
+  public List<V> removeAll(@Nullable Object key) {
+    /*
+     * Safe because all we do is remove values for the key, not add them. (If we wanted to make sure
+     * to call getCopy and removeAllNodes only with a true K, then we could check containsKey first.
+     * But that check wouldn't eliminate the warnings.)
+     */
+    @SuppressWarnings({"unchecked", "nullness"})
+    K castKey = (K) key;
+    List<V> oldValues = getCopy(castKey);
+    removeAllNodes(castKey);
     return oldValues;
   }
 
@@ -675,7 +710,7 @@ public void clear() {
    * <p>The returned list is not serializable and does not have random access.
    */
   @Override
-  public List<V> get(@NullableDecl final K key) {
+  public List<V> get(@ParametricNullness final K key) {
     return new AbstractSequentialList<V>() {
       @Override
       public int size() {
@@ -705,12 +740,12 @@ public Iterator<K> iterator() {
       }
 
       @Override
-      public boolean contains(Object key) { // for performance
+      public boolean contains(@CheckForNull Object key) { // for performance
         return containsKey(key);
       }
 
       @Override
-      public boolean remove(Object o) { // for performance
+      public boolean remove(@CheckForNull Object o) { // for performance
         return !LinkedListMultimap.this.removeAll(o).isEmpty();
       }
     }
@@ -749,12 +784,13 @@ public ListIterator<V> listIterator(int index) {
         final NodeIterator nodeItr = new NodeIterator(index);
         return new TransformedListIterator<Entry<K, V>, V>(nodeItr) {
           @Override
+          @ParametricNullness
           V transform(Entry<K, V> entry) {
             return entry.getValue();
           }
 
           @Override
-          public void set(V value) {
+          public void set(@ParametricNullness V value) {
             nodeItr.setValue(value);
           }
         };
diff --git a/android/guava/src/com/google/common/collect/ListMultimap.java b/android/guava/src/com/google/common/collect/ListMultimap.java
index 46c18ac38614..29e58077cdaa 100644
--- a/android/guava/src/com/google/common/collect/ListMultimap.java
+++ b/android/guava/src/com/google/common/collect/ListMultimap.java
@@ -21,7 +21,8 @@
 import java.util.Collection;
 import java.util.List;
 import java.util.Map;
-import org.checkerframework.checker.nullness.compatqual.NullableDecl;
+import javax.annotation.CheckForNull;
+import org.checkerframework.checker.nullness.qual.Nullable;
 
 /**
  * A {@code Multimap} that can hold duplicate key-value pairs and that maintains the insertion
@@ -33,14 +34,15 @@
  * {@link #asMap} has {@code List} values.
  *
  * <p>See the Guava User Guide article on <a href=
- * "https://github.com/google/guava/wiki/NewCollectionTypesExplained#multimap"> {@code
- * Multimap}</a>.
+ * "https://github.com/google/guava/wiki/NewCollectionTypesExplained#multimap">{@code Multimap}</a>.
  *
  * @author Jared Levy
  * @since 2.0
  */
 @GwtCompatible
-public interface ListMultimap<K, V> extends Multimap<K, V> {
+@ElementTypesAreNonnullByDefault
+public interface ListMultimap<K extends @Nullable Object, V extends @Nullable Object>
+    extends Multimap<K, V> {
   /**
    * {@inheritDoc}
    *
@@ -49,7 +51,7 @@ public interface ListMultimap<K, V> extends Multimap<K, V> {
    * the {@link Multimap} interface.
    */
   @Override
-  List<V> get(@NullableDecl K key);
+  List<V> get(@ParametricNullness K key);
 
   /**
    * {@inheritDoc}
@@ -60,7 +62,7 @@ public interface ListMultimap<K, V> extends Multimap<K, V> {
    */
   @CanIgnoreReturnValue
   @Override
-  List<V> removeAll(@NullableDecl Object key);
+  List<V> removeAll(@CheckForNull Object key);
 
   /**
    * {@inheritDoc}
@@ -71,7 +73,7 @@ public interface ListMultimap<K, V> extends Multimap<K, V> {
    */
   @CanIgnoreReturnValue
   @Override
-  List<V> replaceValues(K key, Iterable<? extends V> values);
+  List<V> replaceValues(@ParametricNullness K key, Iterable<? extends V> values);
 
   /**
    * {@inheritDoc}
@@ -93,5 +95,5 @@ public interface ListMultimap<K, V> extends Multimap<K, V> {
    * empty {@code SetMultimap}.
    */
   @Override
-  boolean equals(@NullableDecl Object obj);
+  boolean equals(@CheckForNull Object obj);
 }
diff --git a/android/guava/src/com/google/common/collect/Lists.java b/android/guava/src/com/google/common/collect/Lists.java
index 33f65339bff4..34fc2258cfe0 100644
--- a/android/guava/src/com/google/common/collect/Lists.java
+++ b/android/guava/src/com/google/common/collect/Lists.java
@@ -48,14 +48,15 @@
 import java.util.NoSuchElementException;
 import java.util.RandomAccess;
 import java.util.concurrent.CopyOnWriteArrayList;
-import org.checkerframework.checker.nullness.compatqual.NullableDecl;
+import javax.annotation.CheckForNull;
+import org.checkerframework.checker.nullness.qual.Nullable;
 
 /**
  * Static utility methods pertaining to {@link List} instances. Also see this class's counterparts
  * {@link Sets}, {@link Maps} and {@link Queues}.
  *
  * <p>See the Guava User Guide article on <a href=
- * "https://github.com/google/guava/wiki/CollectionUtilitiesExplained#lists"> {@code Lists}</a>.
+ * "https://github.com/google/guava/wiki/CollectionUtilitiesExplained#lists">{@code Lists}</a>.
  *
  * @author Kevin Bourrillion
  * @author Mike Bostock
@@ -63,6 +64,7 @@
  * @since 2.0
  */
 @GwtCompatible(emulated = true)
+@ElementTypesAreNonnullByDefault
 public final class Lists {
   private Lists() {}
 
@@ -73,12 +75,12 @@ private Lists() {}
    *
    * <p><b>Note:</b> if mutability is not required, use {@link ImmutableList#of()} instead.
    *
-   * <p><b>Note for Java 7 and later:</b> this method is now unnecessary and should be treated as
-   * deprecated. Instead, use the {@code ArrayList} {@linkplain ArrayList#ArrayList() constructor}
-   * directly, taking advantage of the new <a href="http://goo.gl/iz2Wi">"diamond" syntax</a>.
+   * <p><b>Note:</b> this method is now unnecessary and should be treated as deprecated. Instead,
+   * use the {@code ArrayList} {@linkplain ArrayList#ArrayList() constructor} directly, taking
+   * advantage of <a href="http://goo.gl/iz2Wi">"diamond" syntax</a>.
    */
   @GwtCompatible(serializable = true)
-  public static <E> ArrayList<E> newArrayList() {
+  public static <E extends @Nullable Object> ArrayList<E> newArrayList() {
     return new ArrayList<>();
   }
 
@@ -98,7 +100,7 @@ public static <E> ArrayList<E> newArrayList() {
    */
   @SafeVarargs
   @GwtCompatible(serializable = true)
-  public static <E> ArrayList<E> newArrayList(E... elements) {
+  public static <E extends @Nullable Object> ArrayList<E> newArrayList(E... elements) {
     checkNotNull(elements); // for GWT
     // Avoid integer overflow when a large array is passed in
     int capacity = computeArrayListCapacity(elements.length);
@@ -115,13 +117,13 @@ public static <E> ArrayList<E> newArrayList(E... elements) {
    * ImmutableList#copyOf(Iterable)} instead. (Or, change {@code elements} to be a {@link
    * FluentIterable} and call {@code elements.toList()}.)
    *
-   * <p><b>Note for Java 7 and later:</b> if {@code elements} is a {@link Collection}, you don't
-   * need this method. Use the {@code ArrayList} {@linkplain ArrayList#ArrayList(Collection)
-   * constructor} directly, taking advantage of the new <a href="http://goo.gl/iz2Wi">"diamond"
-   * syntax</a>.
+   * <p><b>Note:</b> if {@code elements} is a {@link Collection}, you don't need this method. Use
+   * the {@code ArrayList} {@linkplain ArrayList#ArrayList(Collection) constructor} directly, taking
+   * advantage of <a href="http://goo.gl/iz2Wi">"diamond" syntax</a>.
    */
   @GwtCompatible(serializable = true)
-  public static <E> ArrayList<E> newArrayList(Iterable<? extends E> elements) {
+  public static <E extends @Nullable Object> ArrayList<E> newArrayList(
+      Iterable<? extends E> elements) {
     checkNotNull(elements); // for GWT
     // Let ArrayList's sizing logic work, if possible
     return (elements instanceof Collection)
@@ -137,7 +139,8 @@ public static <E> ArrayList<E> newArrayList(Iterable<? extends E> elements) {
    * ImmutableList#copyOf(Iterator)} instead.
    */
   @GwtCompatible(serializable = true)
-  public static <E> ArrayList<E> newArrayList(Iterator<? extends E> elements) {
+  public static <E extends @Nullable Object> ArrayList<E> newArrayList(
+      Iterator<? extends E> elements) {
     ArrayList<E> list = newArrayList();
     Iterators.addAll(list, elements);
     return list;
@@ -155,11 +158,11 @@ static int computeArrayListCapacity(int arraySize) {
    * Creates an {@code ArrayList} instance backed by an array with the specified initial size;
    * simply delegates to {@link ArrayList#ArrayList(int)}.
    *
-   * <p><b>Note for Java 7 and later:</b> this method is now unnecessary and should be treated as
-   * deprecated. Instead, use {@code new }{@link ArrayList#ArrayList(int) ArrayList}{@code <>(int)}
-   * directly, taking advantage of the new <a href="http://goo.gl/iz2Wi">"diamond" syntax</a>.
-   * (Unlike here, there is no risk of overload ambiguity, since the {@code ArrayList} constructors
-   * very wisely did not accept varargs.)
+   * <p><b>Note:</b> this method is now unnecessary and should be treated as deprecated. Instead,
+   * use {@code new }{@link ArrayList#ArrayList(int) ArrayList}{@code <>(int)} directly, taking
+   * advantage of <a href="http://goo.gl/iz2Wi">"diamond" syntax</a>. (Unlike here, there is no risk
+   * of overload ambiguity, since the {@code ArrayList} constructors very wisely did not accept
+   * varargs.)
    *
    * @param initialArraySize the exact size of the initial backing array for the returned array list
    *     ({@code ArrayList} documentation calls this value the "capacity")
@@ -168,7 +171,8 @@ static int computeArrayListCapacity(int arraySize) {
    * @throws IllegalArgumentException if {@code initialArraySize} is negative
    */
   @GwtCompatible(serializable = true)
-  public static <E> ArrayList<E> newArrayListWithCapacity(int initialArraySize) {
+  public static <E extends @Nullable Object> ArrayList<E> newArrayListWithCapacity(
+      int initialArraySize) {
     checkNonnegative(initialArraySize, "initialArraySize"); // for GWT.
     return new ArrayList<>(initialArraySize);
   }
@@ -187,7 +191,8 @@ public static <E> ArrayList<E> newArrayListWithCapacity(int initialArraySize) {
    * @throws IllegalArgumentException if {@code estimatedSize} is negative
    */
   @GwtCompatible(serializable = true)
-  public static <E> ArrayList<E> newArrayListWithExpectedSize(int estimatedSize) {
+  public static <E extends @Nullable Object> ArrayList<E> newArrayListWithExpectedSize(
+      int estimatedSize) {
     return new ArrayList<>(computeArrayListCapacity(estimatedSize));
   }
 
@@ -203,13 +208,12 @@ public static <E> ArrayList<E> newArrayListWithExpectedSize(int estimatedSize) {
    * outperform {@code LinkedList} except in certain rare and specific situations. Unless you have
    * spent a lot of time benchmarking your specific needs, use one of those instead.
    *
-   * <p><b>Note for Java 7 and later:</b> this method is now unnecessary and should be treated as
-   * deprecated. Instead, use the {@code LinkedList} {@linkplain LinkedList#LinkedList()
-   * constructor} directly, taking advantage of the new <a href="http://goo.gl/iz2Wi">"diamond"
-   * syntax</a>.
+   * <p><b>Note:</b> this method is now unnecessary and should be treated as deprecated. Instead,
+   * use the {@code LinkedList} {@linkplain LinkedList#LinkedList() constructor} directly, taking
+   * advantage of <a href="http://goo.gl/iz2Wi">"diamond" syntax</a>.
    */
   @GwtCompatible(serializable = true)
-  public static <E> LinkedList<E> newLinkedList() {
+  public static <E extends @Nullable Object> LinkedList<E> newLinkedList() {
     return new LinkedList<>();
   }
 
@@ -225,13 +229,13 @@ public static <E> LinkedList<E> newLinkedList() {
    * outperform {@code LinkedList} except in certain rare and specific situations. Unless you have
    * spent a lot of time benchmarking your specific needs, use one of those instead.
    *
-   * <p><b>Note for Java 7 and later:</b> if {@code elements} is a {@link Collection}, you don't
-   * need this method. Use the {@code LinkedList} {@linkplain LinkedList#LinkedList(Collection)
-   * constructor} directly, taking advantage of the new <a href="http://goo.gl/iz2Wi">"diamond"
-   * syntax</a>.
+   * <p><b>Note:</b> if {@code elements} is a {@link Collection}, you don't need this method. Use
+   * the {@code LinkedList} {@linkplain LinkedList#LinkedList(Collection) constructor} directly,
+   * taking advantage of <a href="http://goo.gl/iz2Wi">"diamond" syntax</a>.
    */
   @GwtCompatible(serializable = true)
-  public static <E> LinkedList<E> newLinkedList(Iterable<? extends E> elements) {
+  public static <E extends @Nullable Object> LinkedList<E> newLinkedList(
+      Iterable<? extends E> elements) {
     LinkedList<E> list = newLinkedList();
     Iterables.addAll(list, elements);
     return list;
@@ -247,7 +251,7 @@ public static <E> LinkedList<E> newLinkedList(Iterable<? extends E> elements) {
    * @since 12.0
    */
   @GwtIncompatible // CopyOnWriteArrayList
-  public static <E> CopyOnWriteArrayList<E> newCopyOnWriteArrayList() {
+  public static <E extends @Nullable Object> CopyOnWriteArrayList<E> newCopyOnWriteArrayList() {
     return new CopyOnWriteArrayList<>();
   }
 
@@ -259,7 +263,7 @@ public static <E> CopyOnWriteArrayList<E> newCopyOnWriteArrayList() {
    * @since 12.0
    */
   @GwtIncompatible // CopyOnWriteArrayList
-  public static <E> CopyOnWriteArrayList<E> newCopyOnWriteArrayList(
+  public static <E extends @Nullable Object> CopyOnWriteArrayList<E> newCopyOnWriteArrayList(
       Iterable<? extends E> elements) {
     // We copy elements to an ArrayList first, rather than incurring the
     // quadratic cost of adding them to the COWAL directly.
@@ -284,7 +288,7 @@ public static <E> CopyOnWriteArrayList<E> newCopyOnWriteArrayList(
    * @param rest an array of additional elements, possibly empty
    * @return an unmodifiable list containing the specified elements
    */
-  public static <E> List<E> asList(@NullableDecl E first, E[] rest) {
+  public static <E extends @Nullable Object> List<E> asList(@ParametricNullness E first, E[] rest) {
     return new OnePlusArrayList<>(first, rest);
   }
 
@@ -304,17 +308,18 @@ public static <E> List<E> asList(@NullableDecl E first, E[] rest) {
    * @param rest an array of additional elements, possibly empty
    * @return an unmodifiable list containing the specified elements
    */
-  public static <E> List<E> asList(@NullableDecl E first, @NullableDecl E second, E[] rest) {
+  public static <E extends @Nullable Object> List<E> asList(
+      @ParametricNullness E first, @ParametricNullness E second, E[] rest) {
     return new TwoPlusArrayList<>(first, second, rest);
   }
 
   /** @see Lists#asList(Object, Object[]) */
-  private static class OnePlusArrayList<E> extends AbstractList<E>
+  private static class OnePlusArrayList<E extends @Nullable Object> extends AbstractList<E>
       implements Serializable, RandomAccess {
-    @NullableDecl final E first;
+    @ParametricNullness final E first;
     final E[] rest;
 
-    OnePlusArrayList(@NullableDecl E first, E[] rest) {
+    OnePlusArrayList(@ParametricNullness E first, E[] rest) {
       this.first = first;
       this.rest = checkNotNull(rest);
     }
@@ -325,6 +330,7 @@ public int size() {
     }
 
     @Override
+    @ParametricNullness
     public E get(int index) {
       // check explicitly so the IOOBE will have the right message
       checkElementIndex(index, size());
@@ -335,13 +341,13 @@ public E get(int index) {
   }
 
   /** @see Lists#asList(Object, Object, Object[]) */
-  private static class TwoPlusArrayList<E> extends AbstractList<E>
+  private static class TwoPlusArrayList<E extends @Nullable Object> extends AbstractList<E>
       implements Serializable, RandomAccess {
-    @NullableDecl final E first;
-    @NullableDecl final E second;
+    @ParametricNullness final E first;
+    @ParametricNullness final E second;
     final E[] rest;
 
-    TwoPlusArrayList(@NullableDecl E first, @NullableDecl E second, E[] rest) {
+    TwoPlusArrayList(@ParametricNullness E first, @ParametricNullness E second, E[] rest) {
       this.first = first;
       this.second = second;
       this.rest = checkNotNull(rest);
@@ -353,6 +359,7 @@ public int size() {
     }
 
     @Override
+    @ParametricNullness
     public E get(int index) {
       switch (index) {
         case 0:
@@ -518,7 +525,7 @@ public static <B> List<List<B>> cartesianProduct(List<? extends B>... lists) {
    * java.util.stream.Stream#map}. This method is not being deprecated, but we gently encourage you
    * to migrate to streams.
    */
-  public static <F, T> List<T> transform(
+  public static <F extends @Nullable Object, T extends @Nullable Object> List<T> transform(
       List<F> fromList, Function<? super F, ? extends T> function) {
     return (fromList instanceof RandomAccess)
         ? new TransformingRandomAccessList<>(fromList, function)
@@ -530,8 +537,9 @@ public static <F, T> List<T> transform(
    *
    * @see Lists#transform
    */
-  private static class TransformingSequentialList<F, T> extends AbstractSequentialList<T>
-      implements Serializable {
+  private static class TransformingSequentialList<
+          F extends @Nullable Object, T extends @Nullable Object>
+      extends AbstractSequentialList<T> implements Serializable {
     final List<F> fromList;
     final Function<? super F, ? extends T> function;
 
@@ -558,7 +566,8 @@ public int size() {
     public ListIterator<T> listIterator(final int index) {
       return new TransformedListIterator<F, T>(fromList.listIterator(index)) {
         @Override
-        T transform(F from) {
+        @ParametricNullness
+        T transform(@ParametricNullness F from) {
           return function.apply(from);
         }
       };
@@ -574,8 +583,9 @@ T transform(F from) {
    *
    * @see Lists#transform
    */
-  private static class TransformingRandomAccessList<F, T> extends AbstractList<T>
-      implements RandomAccess, Serializable {
+  private static class TransformingRandomAccessList<
+          F extends @Nullable Object, T extends @Nullable Object>
+      extends AbstractList<T> implements RandomAccess, Serializable {
     final List<F> fromList;
     final Function<? super F, ? extends T> function;
 
@@ -590,6 +600,7 @@ public void clear() {
     }
 
     @Override
+    @ParametricNullness
     public T get(int index) {
       return function.apply(fromList.get(index));
     }
@@ -642,7 +653,7 @@ public int size() {
    * @return a list of consecutive sublists
    * @throws IllegalArgumentException if {@code partitionSize} is nonpositive
    */
-  public static <T> List<List<T>> partition(List<T> list, int size) {
+  public static <T extends @Nullable Object> List<List<T>> partition(List<T> list, int size) {
     checkNotNull(list);
     checkArgument(size > 0);
     return (list instanceof RandomAccess)
@@ -650,7 +661,7 @@ public static <T> List<List<T>> partition(List<T> list, int size) {
         : new Partition<>(list, size);
   }
 
-  private static class Partition<T> extends AbstractList<List<T>> {
+  private static class Partition<T extends @Nullable Object> extends AbstractList<List<T>> {
     final List<T> list;
     final int size;
 
@@ -678,7 +689,8 @@ public boolean isEmpty() {
     }
   }
 
-  private static class RandomAccessPartition<T> extends Partition<T> implements RandomAccess {
+  private static class RandomAccessPartition<T extends @Nullable Object> extends Partition<T>
+      implements RandomAccess {
     RandomAccessPartition(List<T> list, int size) {
       super(list, size);
     }
@@ -717,12 +729,12 @@ private static final class StringAsImmutableList extends ImmutableList<Character
     }
 
     @Override
-    public int indexOf(@NullableDecl Object object) {
+    public int indexOf(@CheckForNull Object object) {
       return (object instanceof Character) ? string.indexOf((Character) object) : -1;
     }
 
     @Override
-    public int lastIndexOf(@NullableDecl Object object) {
+    public int lastIndexOf(@CheckForNull Object object) {
       return (object instanceof Character) ? string.lastIndexOf((Character) object) : -1;
     }
 
@@ -779,9 +791,13 @@ public int size() {
    *
    * @since 7.0
    */
-  public static <T> List<T> reverse(List<T> list) {
+  public static <T extends @Nullable Object> List<T> reverse(List<T> list) {
     if (list instanceof ImmutableList) {
-      return ((ImmutableList<T>) list).reverse();
+      // Avoid nullness warnings.
+      List<?> reversed = ((ImmutableList<?>) list).reverse();
+      @SuppressWarnings("unchecked")
+      List<T> result = (List<T>) reversed;
+      return result;
     } else if (list instanceof ReverseList) {
       return ((ReverseList<T>) list).getForwardList();
     } else if (list instanceof RandomAccess) {
@@ -791,7 +807,7 @@ public static <T> List<T> reverse(List<T> list) {
     }
   }
 
-  private static class ReverseList<T> extends AbstractList<T> {
+  private static class ReverseList<T extends @Nullable Object> extends AbstractList<T> {
     private final List<T> forwardList;
 
     ReverseList(List<T> forwardList) {
@@ -815,7 +831,7 @@ private int reversePosition(int index) {
     }
 
     @Override
-    public void add(int index, @NullableDecl T element) {
+    public void add(int index, @ParametricNullness T element) {
       forwardList.add(reversePosition(index), element);
     }
 
@@ -825,6 +841,7 @@ public void clear() {
     }
 
     @Override
+    @ParametricNullness
     public T remove(int index) {
       return forwardList.remove(reverseIndex(index));
     }
@@ -835,11 +852,13 @@ protected void removeRange(int fromIndex, int toIndex) {
     }
 
     @Override
-    public T set(int index, @NullableDecl T element) {
+    @ParametricNullness
+    public T set(int index, @ParametricNullness T element) {
       return forwardList.set(reverseIndex(index), element);
     }
 
     @Override
+    @ParametricNullness
     public T get(int index) {
       return forwardList.get(reverseIndex(index));
     }
@@ -869,7 +888,7 @@ public ListIterator<T> listIterator(int index) {
         boolean canRemoveOrSet;
 
         @Override
-        public void add(T e) {
+        public void add(@ParametricNullness T e) {
           forwardIterator.add(e);
           forwardIterator.previous();
           canRemoveOrSet = false;
@@ -886,6 +905,7 @@ public boolean hasPrevious() {
         }
 
         @Override
+        @ParametricNullness
         public T next() {
           if (!hasNext()) {
             throw new NoSuchElementException();
@@ -900,6 +920,7 @@ public int nextIndex() {
         }
 
         @Override
+        @ParametricNullness
         public T previous() {
           if (!hasPrevious()) {
             throw new NoSuchElementException();
@@ -921,7 +942,7 @@ public void remove() {
         }
 
         @Override
-        public void set(T e) {
+        public void set(@ParametricNullness T e) {
           checkState(canRemoveOrSet);
           forwardIterator.set(e);
         }
@@ -929,7 +950,8 @@ public void set(T e) {
     }
   }
 
-  private static class RandomAccessReverseList<T> extends ReverseList<T> implements RandomAccess {
+  private static class RandomAccessReverseList<T extends @Nullable Object> extends ReverseList<T>
+      implements RandomAccess {
     RandomAccessReverseList(List<T> forwardList) {
       super(forwardList);
     }
@@ -949,7 +971,7 @@ static int hashCodeImpl(List<?> list) {
   }
 
   /** An implementation of {@link List#equals(Object)}. */
-  static boolean equalsImpl(List<?> thisList, @NullableDecl Object other) {
+  static boolean equalsImpl(List<?> thisList, @CheckForNull Object other) {
     if (other == checkNotNull(thisList)) {
       return true;
     }
@@ -975,7 +997,8 @@ static boolean equalsImpl(List<?> thisList, @NullableDecl Object other) {
   }
 
   /** An implementation of {@link List#addAll(int, Collection)}. */
-  static <E> boolean addAllImpl(List<E> list, int index, Iterable<? extends E> elements) {
+  static <E extends @Nullable Object> boolean addAllImpl(
+      List<E> list, int index, Iterable<? extends E> elements) {
     boolean changed = false;
     ListIterator<E> listIterator = list.listIterator(index);
     for (E e : elements) {
@@ -986,7 +1009,7 @@ static <E> boolean addAllImpl(List<E> list, int index, Iterable<? extends E> ele
   }
 
   /** An implementation of {@link List#indexOf(Object)}. */
-  static int indexOfImpl(List<?> list, @NullableDecl Object element) {
+  static int indexOfImpl(List<?> list, @CheckForNull Object element) {
     if (list instanceof RandomAccess) {
       return indexOfRandomAccess(list, element);
     } else {
@@ -1000,7 +1023,7 @@ static int indexOfImpl(List<?> list, @NullableDecl Object element) {
     }
   }
 
-  private static int indexOfRandomAccess(List<?> list, @NullableDecl Object element) {
+  private static int indexOfRandomAccess(List<?> list, @CheckForNull Object element) {
     int size = list.size();
     if (element == null) {
       for (int i = 0; i < size; i++) {
@@ -1019,7 +1042,7 @@ private static int indexOfRandomAccess(List<?> list, @NullableDecl Object elemen
   }
 
   /** An implementation of {@link List#lastIndexOf(Object)}. */
-  static int lastIndexOfImpl(List<?> list, @NullableDecl Object element) {
+  static int lastIndexOfImpl(List<?> list, @CheckForNull Object element) {
     if (list instanceof RandomAccess) {
       return lastIndexOfRandomAccess(list, element);
     } else {
@@ -1033,7 +1056,7 @@ static int lastIndexOfImpl(List<?> list, @NullableDecl Object element) {
     }
   }
 
-  private static int lastIndexOfRandomAccess(List<?> list, @NullableDecl Object element) {
+  private static int lastIndexOfRandomAccess(List<?> list, @CheckForNull Object element) {
     if (element == null) {
       for (int i = list.size() - 1; i >= 0; i--) {
         if (list.get(i) == null) {
@@ -1051,12 +1074,13 @@ private static int lastIndexOfRandomAccess(List<?> list, @NullableDecl Object el
   }
 
   /** Returns an implementation of {@link List#listIterator(int)}. */
-  static <E> ListIterator<E> listIteratorImpl(List<E> list, int index) {
+  static <E extends @Nullable Object> ListIterator<E> listIteratorImpl(List<E> list, int index) {
     return new AbstractListWrapper<>(list).listIterator(index);
   }
 
   /** An implementation of {@link List#subList(int, int)}. */
-  static <E> List<E> subListImpl(final List<E> list, int fromIndex, int toIndex) {
+  static <E extends @Nullable Object> List<E> subListImpl(
+      final List<E> list, int fromIndex, int toIndex) {
     List<E> wrapper;
     if (list instanceof RandomAccess) {
       wrapper =
@@ -1082,7 +1106,7 @@ public ListIterator<E> listIterator(int index) {
     return wrapper.subList(fromIndex, toIndex);
   }
 
-  private static class AbstractListWrapper<E> extends AbstractList<E> {
+  private static class AbstractListWrapper<E extends @Nullable Object> extends AbstractList<E> {
     final List<E> backingList;
 
     AbstractListWrapper(List<E> backingList) {
@@ -1090,7 +1114,7 @@ private static class AbstractListWrapper<E> extends AbstractList<E> {
     }
 
     @Override
-    public void add(int index, E element) {
+    public void add(int index, @ParametricNullness E element) {
       backingList.add(index, element);
     }
 
@@ -1100,22 +1124,25 @@ public boolean addAll(int index, Collection<? extends E> c) {
     }
 
     @Override
+    @ParametricNullness
     public E get(int index) {
       return backingList.get(index);
     }
 
     @Override
+    @ParametricNullness
     public E remove(int index) {
       return backingList.remove(index);
     }
 
     @Override
-    public E set(int index, E element) {
+    @ParametricNullness
+    public E set(int index, @ParametricNullness E element) {
       return backingList.set(index, element);
     }
 
     @Override
-    public boolean contains(Object o) {
+    public boolean contains(@CheckForNull Object o) {
       return backingList.contains(o);
     }
 
@@ -1125,15 +1152,15 @@ public int size() {
     }
   }
 
-  private static class RandomAccessListWrapper<E> extends AbstractListWrapper<E>
-      implements RandomAccess {
+  private static class RandomAccessListWrapper<E extends @Nullable Object>
+      extends AbstractListWrapper<E> implements RandomAccess {
     RandomAccessListWrapper(List<E> backingList) {
       super(backingList);
     }
   }
 
   /** Used to avoid http://bugs.sun.com/view_bug.do?bug_id=6558557 */
-  static <T> List<T> cast(Iterable<T> iterable) {
+  static <T extends @Nullable Object> List<T> cast(Iterable<T> iterable) {
     return (List<T>) iterable;
   }
 }
diff --git a/android/guava/src/com/google/common/collect/MapDifference.java b/android/guava/src/com/google/common/collect/MapDifference.java
index 9933770cb4e4..5000e4b527c1 100644
--- a/android/guava/src/com/google/common/collect/MapDifference.java
+++ b/android/guava/src/com/google/common/collect/MapDifference.java
@@ -19,7 +19,8 @@
 import com.google.common.annotations.GwtCompatible;
 import com.google.errorprone.annotations.DoNotMock;
 import java.util.Map;
-import org.checkerframework.checker.nullness.compatqual.NullableDecl;
+import javax.annotation.CheckForNull;
+import org.checkerframework.checker.nullness.qual.Nullable;
 
 /**
  * An object representing the differences between two maps.
@@ -29,7 +30,8 @@
  */
 @DoNotMock("Use Maps.difference")
 @GwtCompatible
-public interface MapDifference<K, V> {
+@ElementTypesAreNonnullByDefault
+public interface MapDifference<K extends @Nullable Object, V extends @Nullable Object> {
   /**
    * Returns {@code true} if there are no differences between the two maps; that is, if the maps are
    * equal.
@@ -67,7 +69,7 @@ public interface MapDifference<K, V> {
    * #entriesDiffering()} of the two instances are equal.
    */
   @Override
-  boolean equals(@NullableDecl Object object);
+  boolean equals(@CheckForNull Object object);
 
   /**
    * Returns the hash code for this instance. This is defined as the hash code of
@@ -87,11 +89,13 @@ public interface MapDifference<K, V> {
    * @since 2.0
    */
   @DoNotMock("Use Maps.difference")
-  interface ValueDifference<V> {
+  interface ValueDifference<V extends @Nullable Object> {
     /** Returns the value from the left map (possibly null). */
+    @ParametricNullness
     V leftValue();
 
     /** Returns the value from the right map (possibly null). */
+    @ParametricNullness
     V rightValue();
 
     /**
@@ -99,7 +103,7 @@ interface ValueDifference<V> {
      * {@link #rightValue()} values are also equal.
      */
     @Override
-    boolean equals(@NullableDecl Object other);
+    boolean equals(@CheckForNull Object other);
 
     /**
      * The hash code equals the value {@code Arrays.asList(leftValue(), rightValue()).hashCode()}.
diff --git a/android/guava/src/com/google/common/collect/MapMaker.java b/android/guava/src/com/google/common/collect/MapMaker.java
index 4f837a0d3306..a2612c1bd286 100644
--- a/android/guava/src/com/google/common/collect/MapMaker.java
+++ b/android/guava/src/com/google/common/collect/MapMaker.java
@@ -30,7 +30,7 @@
 import java.util.Map;
 import java.util.concurrent.ConcurrentHashMap;
 import java.util.concurrent.ConcurrentMap;
-import org.checkerframework.checker.nullness.compatqual.NullableDecl;
+import javax.annotation.CheckForNull;
 
 /**
  * A builder of {@link ConcurrentMap} instances that can have keys or values automatically wrapped
@@ -86,6 +86,7 @@
  * @since 2.0
  */
 @GwtCompatible(emulated = true)
+@ElementTypesAreNonnullByDefault
 public final class MapMaker {
   private static final int DEFAULT_INITIAL_CAPACITY = 16;
   private static final int DEFAULT_CONCURRENCY_LEVEL = 4;
@@ -98,10 +99,10 @@ public final class MapMaker {
   int initialCapacity = UNSET_INT;
   int concurrencyLevel = UNSET_INT;
 
-  @NullableDecl Strength keyStrength;
-  @NullableDecl Strength valueStrength;
+  @CheckForNull Strength keyStrength;
+  @CheckForNull Strength valueStrength;
 
-  @NullableDecl Equivalence<Object> keyEquivalence;
+  @CheckForNull Equivalence<Object> keyEquivalence;
 
   /**
    * Constructs a new {@code MapMaker} instance with default settings, including strong keys, strong
diff --git a/android/guava/src/com/google/common/collect/MapMakerInternalMap.java b/android/guava/src/com/google/common/collect/MapMakerInternalMap.java
index b72d0ea54371..bdef10ebc9e4 100644
--- a/android/guava/src/com/google/common/collect/MapMakerInternalMap.java
+++ b/android/guava/src/com/google/common/collect/MapMakerInternalMap.java
@@ -47,7 +47,7 @@
 import java.util.concurrent.atomic.AtomicInteger;
 import java.util.concurrent.atomic.AtomicReferenceArray;
 import java.util.concurrent.locks.ReentrantLock;
-import org.checkerframework.checker.nullness.compatqual.NullableDecl;
+import javax.annotation.CheckForNull;
 
 /**
  * The concurrent hash map implementation built by {@link MapMaker}.
@@ -65,7 +65,11 @@
  */
 // TODO(kak): Consider removing @CanIgnoreReturnValue from this class.
 @GwtIncompatible
-@SuppressWarnings("GuardedBy") // TODO(b/35466881): Fix or suppress.
+@SuppressWarnings({
+  "GuardedBy", // TODO(b/35466881): Fix or suppress.
+  "nullness", // too much trouble for the payoff
+})
+// TODO(cpovirk): Annotate for nullness.
 class MapMakerInternalMap<
         K,
         V,
@@ -291,13 +295,13 @@ interface InternalEntryHelper<
     /**
      * Returns a freshly created entry, typed at the {@code E} type, for the given {@code segment}.
      */
-    E newEntry(S segment, K key, int hash, @NullableDecl E next);
+    E newEntry(S segment, K key, int hash, @CheckForNull E next);
 
     /**
      * Returns a freshly created entry, typed at the {@code E} type, for the given {@code segment},
      * that is a copy of the given {@code entry}.
      */
-    E copy(S segment, E entry, @NullableDecl E newNext);
+    E copy(S segment, E entry, @CheckForNull E newNext);
 
     /**
      * Sets the value of the given {@code entry} in the given {@code segment} to be the given {@code
@@ -339,9 +343,9 @@ abstract static class AbstractStrongKeyEntry<K, V, E extends InternalEntry<K, V,
       implements InternalEntry<K, V, E> {
     final K key;
     final int hash;
-    @NullableDecl final E next;
+    @CheckForNull final E next;
 
-    AbstractStrongKeyEntry(K key, int hash, @NullableDecl E next) {
+    AbstractStrongKeyEntry(K key, int hash, @CheckForNull E next) {
       this.key = key;
       this.hash = hash;
       this.next = next;
@@ -389,14 +393,14 @@ WeakValueReference<K, V, E> unsetWeakValueReference() {
   static final class StrongKeyStrongValueEntry<K, V>
       extends AbstractStrongKeyEntry<K, V, StrongKeyStrongValueEntry<K, V>>
       implements StrongValueEntry<K, V, StrongKeyStrongValueEntry<K, V>> {
-    @NullableDecl private volatile V value = null;
+    @CheckForNull private volatile V value = null;
 
-    StrongKeyStrongValueEntry(K key, int hash, @NullableDecl StrongKeyStrongValueEntry<K, V> next) {
+    StrongKeyStrongValueEntry(K key, int hash, @CheckForNull StrongKeyStrongValueEntry<K, V> next) {
       super(key, hash, next);
     }
 
     @Override
-    @NullableDecl
+    @CheckForNull
     public V getValue() {
       return value;
     }
@@ -447,7 +451,7 @@ public StrongKeyStrongValueSegment<K, V> newSegment(
       public StrongKeyStrongValueEntry<K, V> copy(
           StrongKeyStrongValueSegment<K, V> segment,
           StrongKeyStrongValueEntry<K, V> entry,
-          @NullableDecl StrongKeyStrongValueEntry<K, V> newNext) {
+          @CheckForNull StrongKeyStrongValueEntry<K, V> newNext) {
         return entry.copy(newNext);
       }
 
@@ -464,7 +468,7 @@ public StrongKeyStrongValueEntry<K, V> newEntry(
           StrongKeyStrongValueSegment<K, V> segment,
           K key,
           int hash,
-          @NullableDecl StrongKeyStrongValueEntry<K, V> next) {
+          @CheckForNull StrongKeyStrongValueEntry<K, V> next) {
         return new StrongKeyStrongValueEntry<>(key, hash, next);
       }
     }
@@ -477,7 +481,7 @@ static final class StrongKeyWeakValueEntry<K, V>
     private volatile WeakValueReference<K, V, StrongKeyWeakValueEntry<K, V>> valueReference =
         unsetWeakValueReference();
 
-    StrongKeyWeakValueEntry(K key, int hash, @NullableDecl StrongKeyWeakValueEntry<K, V> next) {
+    StrongKeyWeakValueEntry(K key, int hash, @CheckForNull StrongKeyWeakValueEntry<K, V> next) {
       super(key, hash, next);
     }
 
@@ -543,7 +547,7 @@ public StrongKeyWeakValueSegment<K, V> newSegment(
       public StrongKeyWeakValueEntry<K, V> copy(
           StrongKeyWeakValueSegment<K, V> segment,
           StrongKeyWeakValueEntry<K, V> entry,
-          @NullableDecl StrongKeyWeakValueEntry<K, V> newNext) {
+          @CheckForNull StrongKeyWeakValueEntry<K, V> newNext) {
         if (Segment.isCollected(entry)) {
           return null;
         }
@@ -561,7 +565,7 @@ public StrongKeyWeakValueEntry<K, V> newEntry(
           StrongKeyWeakValueSegment<K, V> segment,
           K key,
           int hash,
-          @NullableDecl StrongKeyWeakValueEntry<K, V> next) {
+          @CheckForNull StrongKeyWeakValueEntry<K, V> next) {
         return new StrongKeyWeakValueEntry<>(key, hash, next);
       }
     }
@@ -571,7 +575,7 @@ public StrongKeyWeakValueEntry<K, V> newEntry(
   static final class StrongKeyDummyValueEntry<K>
       extends AbstractStrongKeyEntry<K, Dummy, StrongKeyDummyValueEntry<K>>
       implements StrongValueEntry<K, Dummy, StrongKeyDummyValueEntry<K>> {
-    StrongKeyDummyValueEntry(K key, int hash, @NullableDecl StrongKeyDummyValueEntry<K> next) {
+    StrongKeyDummyValueEntry(K key, int hash, @CheckForNull StrongKeyDummyValueEntry<K> next) {
       super(key, hash, next);
     }
 
@@ -623,7 +627,7 @@ public StrongKeyDummyValueSegment<K> newSegment(
       public StrongKeyDummyValueEntry<K> copy(
           StrongKeyDummyValueSegment<K> segment,
           StrongKeyDummyValueEntry<K> entry,
-          @NullableDecl StrongKeyDummyValueEntry<K> newNext) {
+          @CheckForNull StrongKeyDummyValueEntry<K> newNext) {
         return entry.copy(newNext);
       }
 
@@ -636,7 +640,7 @@ public StrongKeyDummyValueEntry<K> newEntry(
           StrongKeyDummyValueSegment<K> segment,
           K key,
           int hash,
-          @NullableDecl StrongKeyDummyValueEntry<K> next) {
+          @CheckForNull StrongKeyDummyValueEntry<K> next) {
         return new StrongKeyDummyValueEntry<K>(key, hash, next);
       }
     }
@@ -646,9 +650,9 @@ public StrongKeyDummyValueEntry<K> newEntry(
   abstract static class AbstractWeakKeyEntry<K, V, E extends InternalEntry<K, V, E>>
       extends WeakReference<K> implements InternalEntry<K, V, E> {
     final int hash;
-    @NullableDecl final E next;
+    @CheckForNull final E next;
 
-    AbstractWeakKeyEntry(ReferenceQueue<K> queue, K key, int hash, @NullableDecl E next) {
+    AbstractWeakKeyEntry(ReferenceQueue<K> queue, K key, int hash, @CheckForNull E next) {
       super(key, queue);
       this.hash = hash;
       this.next = next;
@@ -675,7 +679,7 @@ static final class WeakKeyDummyValueEntry<K>
       extends AbstractWeakKeyEntry<K, Dummy, WeakKeyDummyValueEntry<K>>
       implements StrongValueEntry<K, Dummy, WeakKeyDummyValueEntry<K>> {
     WeakKeyDummyValueEntry(
-        ReferenceQueue<K> queue, K key, int hash, @NullableDecl WeakKeyDummyValueEntry<K> next) {
+        ReferenceQueue<K> queue, K key, int hash, @CheckForNull WeakKeyDummyValueEntry<K> next) {
       super(queue, key, hash, next);
     }
 
@@ -727,7 +731,7 @@ public WeakKeyDummyValueSegment<K> newSegment(
       public WeakKeyDummyValueEntry<K> copy(
           WeakKeyDummyValueSegment<K> segment,
           WeakKeyDummyValueEntry<K> entry,
-          @NullableDecl WeakKeyDummyValueEntry<K> newNext) {
+          @CheckForNull WeakKeyDummyValueEntry<K> newNext) {
         if (entry.getKey() == null) {
           // key collected
           return null;
@@ -744,7 +748,7 @@ public WeakKeyDummyValueEntry<K> newEntry(
           WeakKeyDummyValueSegment<K> segment,
           K key,
           int hash,
-          @NullableDecl WeakKeyDummyValueEntry<K> next) {
+          @CheckForNull WeakKeyDummyValueEntry<K> next) {
         return new WeakKeyDummyValueEntry<K>(segment.queueForKeys, key, hash, next);
       }
     }
@@ -754,18 +758,18 @@ public WeakKeyDummyValueEntry<K> newEntry(
   static final class WeakKeyStrongValueEntry<K, V>
       extends AbstractWeakKeyEntry<K, V, WeakKeyStrongValueEntry<K, V>>
       implements StrongValueEntry<K, V, WeakKeyStrongValueEntry<K, V>> {
-    @NullableDecl private volatile V value = null;
+    @CheckForNull private volatile V value = null;
 
     WeakKeyStrongValueEntry(
         ReferenceQueue<K> queue,
         K key,
         int hash,
-        @NullableDecl WeakKeyStrongValueEntry<K, V> next) {
+        @CheckForNull WeakKeyStrongValueEntry<K, V> next) {
       super(queue, key, hash, next);
     }
 
     @Override
-    @NullableDecl
+    @CheckForNull
     public V getValue() {
       return value;
     }
@@ -816,7 +820,7 @@ public WeakKeyStrongValueSegment<K, V> newSegment(
       public WeakKeyStrongValueEntry<K, V> copy(
           WeakKeyStrongValueSegment<K, V> segment,
           WeakKeyStrongValueEntry<K, V> entry,
-          @NullableDecl WeakKeyStrongValueEntry<K, V> newNext) {
+          @CheckForNull WeakKeyStrongValueEntry<K, V> newNext) {
         if (entry.getKey() == null) {
           // key collected
           return null;
@@ -835,7 +839,7 @@ public WeakKeyStrongValueEntry<K, V> newEntry(
           WeakKeyStrongValueSegment<K, V> segment,
           K key,
           int hash,
-          @NullableDecl WeakKeyStrongValueEntry<K, V> next) {
+          @CheckForNull WeakKeyStrongValueEntry<K, V> next) {
         return new WeakKeyStrongValueEntry<>(segment.queueForKeys, key, hash, next);
       }
     }
@@ -849,7 +853,7 @@ static final class WeakKeyWeakValueEntry<K, V>
         unsetWeakValueReference();
 
     WeakKeyWeakValueEntry(
-        ReferenceQueue<K> queue, K key, int hash, @NullableDecl WeakKeyWeakValueEntry<K, V> next) {
+        ReferenceQueue<K> queue, K key, int hash, @CheckForNull WeakKeyWeakValueEntry<K, V> next) {
       super(queue, key, hash, next);
     }
 
@@ -917,7 +921,7 @@ public WeakKeyWeakValueSegment<K, V> newSegment(
       public WeakKeyWeakValueEntry<K, V> copy(
           WeakKeyWeakValueSegment<K, V> segment,
           WeakKeyWeakValueEntry<K, V> entry,
-          @NullableDecl WeakKeyWeakValueEntry<K, V> newNext) {
+          @CheckForNull WeakKeyWeakValueEntry<K, V> newNext) {
         if (entry.getKey() == null) {
           // key collected
           return null;
@@ -939,7 +943,7 @@ public WeakKeyWeakValueEntry<K, V> newEntry(
           WeakKeyWeakValueSegment<K, V> segment,
           K key,
           int hash,
-          @NullableDecl WeakKeyWeakValueEntry<K, V> next) {
+          @CheckForNull WeakKeyWeakValueEntry<K, V> next) {
         return new WeakKeyWeakValueEntry<>(segment.queueForKeys, key, hash, next);
       }
     }
@@ -951,7 +955,7 @@ interface WeakValueReference<K, V, E extends InternalEntry<K, V, E>> {
      * Returns the current value being referenced, or {@code null} if there is none (e.g. because
      * either it got collected, or {@link #clear} was called, or it wasn't set in the first place).
      */
-    @NullableDecl
+    @CheckForNull
     V get();
 
     /** Returns the entry which contains this {@link WeakValueReference}. */
@@ -1193,7 +1197,7 @@ abstract static class Segment<
     int threshold;
 
     /** The per-segment table. */
-    @NullableDecl volatile AtomicReferenceArray<E> table;
+    @CheckForNull volatile AtomicReferenceArray<E> table;
 
     /** The maximum size of this map. MapMaker.UNSET_INT if there is no maximum. */
     final int maxSegmentSize;
@@ -1301,7 +1305,7 @@ void setTableEntryForTesting(int i, InternalEntry<K, V, ?> entry) {
     }
 
     /** Unsafely returns a copy of the given entry. */
-    E copyForTesting(InternalEntry<K, V, ?> entry, @NullableDecl InternalEntry<K, V, ?> newNext) {
+    E copyForTesting(InternalEntry<K, V, ?> entry, @CheckForNull InternalEntry<K, V, ?> newNext) {
       return this.map.entryHelper.copy(self(), castForTesting(entry), castForTesting(newNext));
     }
 
@@ -1311,7 +1315,7 @@ void setValueForTesting(InternalEntry<K, V, ?> entry, V value) {
     }
 
     /** Unsafely returns a fresh entry. */
-    E newEntryForTesting(K key, int hash, @NullableDecl InternalEntry<K, V, ?> next) {
+    E newEntryForTesting(K key, int hash, @CheckForNull InternalEntry<K, V, ?> next) {
       return this.map.entryHelper.newEntry(self(), key, hash, castForTesting(next));
     }
 
@@ -1329,7 +1333,7 @@ E removeFromChainForTesting(InternalEntry<K, V, ?> first, InternalEntry<K, V, ?>
     /**
      * Unsafely returns the value of the given entry if it's still live, or {@code null} otherwise.
      */
-    @NullableDecl
+    @CheckForNull
     V getLiveValueForTesting(InternalEntry<K, V, ?> entry) {
       return getLiveValue(castForTesting(entry));
     }
@@ -1944,7 +1948,7 @@ static <K, V, E extends InternalEntry<K, V, E>> boolean isCollected(E entry) {
      * Gets the value from an entry. Returns {@code null} if the entry is invalid or
      * partially-collected.
      */
-    @NullableDecl
+    @CheckForNull
     V getLiveValue(E entry) {
       if (entry.getKey() == null) {
         tryDrainReferenceQueues();
@@ -2335,7 +2339,7 @@ public int size() {
   }
 
   @Override
-  public V get(@NullableDecl Object key) {
+  public V get(@CheckForNull Object key) {
     if (key == null) {
       return null;
     }
@@ -2347,7 +2351,7 @@ public V get(@NullableDecl Object key) {
    * Returns the internal entry for the specified key. The entry may be computing or partially
    * collected. Does not impact recency ordering.
    */
-  E getEntry(@NullableDecl Object key) {
+  E getEntry(@CheckForNull Object key) {
     if (key == null) {
       return null;
     }
@@ -2356,7 +2360,7 @@ E getEntry(@NullableDecl Object key) {
   }
 
   @Override
-  public boolean containsKey(@NullableDecl Object key) {
+  public boolean containsKey(@CheckForNull Object key) {
     if (key == null) {
       return false;
     }
@@ -2365,7 +2369,7 @@ public boolean containsKey(@NullableDecl Object key) {
   }
 
   @Override
-  public boolean containsValue(@NullableDecl Object value) {
+  public boolean containsValue(@CheckForNull Object value) {
     if (value == null) {
       return false;
     }
@@ -2429,7 +2433,7 @@ public void putAll(Map<? extends K, ? extends V> m) {
 
   @CanIgnoreReturnValue
   @Override
-  public V remove(@NullableDecl Object key) {
+  public V remove(@CheckForNull Object key) {
     if (key == null) {
       return null;
     }
@@ -2439,7 +2443,7 @@ public V remove(@NullableDecl Object key) {
 
   @CanIgnoreReturnValue
   @Override
-  public boolean remove(@NullableDecl Object key, @NullableDecl Object value) {
+  public boolean remove(@CheckForNull Object key, @CheckForNull Object value) {
     if (key == null || value == null) {
       return false;
     }
@@ -2449,7 +2453,7 @@ public boolean remove(@NullableDecl Object key, @NullableDecl Object value) {
 
   @CanIgnoreReturnValue
   @Override
-  public boolean replace(K key, @NullableDecl V oldValue, V newValue) {
+  public boolean replace(K key, @CheckForNull V oldValue, V newValue) {
     checkNotNull(key);
     checkNotNull(newValue);
     if (oldValue == null) {
@@ -2475,7 +2479,7 @@ public void clear() {
     }
   }
 
-  @NullableDecl transient Set<K> keySet;
+  @CheckForNull transient Set<K> keySet;
 
   @Override
   public Set<K> keySet() {
@@ -2483,7 +2487,7 @@ public Set<K> keySet() {
     return (ks != null) ? ks : (keySet = new KeySet());
   }
 
-  @NullableDecl transient Collection<V> values;
+  @CheckForNull transient Collection<V> values;
 
   @Override
   public Collection<V> values() {
@@ -2491,7 +2495,7 @@ public Collection<V> values() {
     return (vs != null) ? vs : (values = new Values());
   }
 
-  @NullableDecl transient Set<Entry<K, V>> entrySet;
+  @CheckForNull transient Set<Entry<K, V>> entrySet;
 
   @Override
   public Set<Entry<K, V>> entrySet() {
@@ -2505,11 +2509,11 @@ abstract class HashIterator<T> implements Iterator<T> {
 
     int nextSegmentIndex;
     int nextTableIndex;
-    @NullableDecl Segment<K, V, E, S> currentSegment;
-    @NullableDecl AtomicReferenceArray<E> currentTable;
-    @NullableDecl E nextEntry;
-    @NullableDecl WriteThroughEntry nextExternal;
-    @NullableDecl WriteThroughEntry lastReturned;
+    @CheckForNull Segment<K, V, E, S> currentSegment;
+    @CheckForNull AtomicReferenceArray<E> currentTable;
+    @CheckForNull E nextEntry;
+    @CheckForNull WriteThroughEntry nextExternal;
+    @CheckForNull WriteThroughEntry lastReturned;
 
     HashIterator() {
       nextSegmentIndex = segments.length - 1;
@@ -2649,7 +2653,7 @@ public V getValue() {
     }
 
     @Override
-    public boolean equals(@NullableDecl Object object) {
+    public boolean equals(@CheckForNull Object object) {
       // Cannot use key and value equivalence
       if (object instanceof Entry) {
         Entry<?, ?> that = (Entry<?, ?>) object;
diff --git a/android/guava/src/com/google/common/collect/Maps.java b/android/guava/src/com/google/common/collect/Maps.java
index f0bac2ad0196..76e69abb79c0 100644
--- a/android/guava/src/com/google/common/collect/Maps.java
+++ b/android/guava/src/com/google/common/collect/Maps.java
@@ -21,6 +21,8 @@
 import static com.google.common.base.Predicates.compose;
 import static com.google.common.collect.CollectPreconditions.checkEntryNotNull;
 import static com.google.common.collect.CollectPreconditions.checkNonnegative;
+import static com.google.common.collect.NullnessCasts.uncheckedCastNullableTToT;
+import static java.util.Objects.requireNonNull;
 
 import com.google.common.annotations.Beta;
 import com.google.common.annotations.GwtCompatible;
@@ -61,7 +63,8 @@
 import java.util.TreeMap;
 import java.util.concurrent.ConcurrentHashMap;
 import java.util.concurrent.ConcurrentMap;
-import org.checkerframework.checker.nullness.compatqual.NullableDecl;
+import javax.annotation.CheckForNull;
+import org.checkerframework.checker.nullness.qual.Nullable;
 
 /**
  * Static utility methods pertaining to {@link Map} instances (including instances of {@link
@@ -69,7 +72,7 @@
  * and {@link Queues}.
  *
  * <p>See the Guava User Guide article on <a href=
- * "https://github.com/google/guava/wiki/CollectionUtilitiesExplained#maps"> {@code Maps}</a>.
+ * "https://github.com/google/guava/wiki/CollectionUtilitiesExplained#maps">{@code Maps}</a>.
  *
  * @author Kevin Bourrillion
  * @author Mike Bostock
@@ -78,20 +81,21 @@
  * @since 2.0
  */
 @GwtCompatible(emulated = true)
+@ElementTypesAreNonnullByDefault
 public final class Maps {
   private Maps() {}
 
-  private enum EntryFunction implements Function<Entry<?, ?>, Object> {
+  private enum EntryFunction implements Function<Entry<?, ?>, @Nullable Object> {
     KEY {
       @Override
-      @NullableDecl
+      @CheckForNull
       public Object apply(Entry<?, ?> entry) {
         return entry.getKey();
       }
     },
     VALUE {
       @Override
-      @NullableDecl
+      @CheckForNull
       public Object apply(Entry<?, ?> entry) {
         return entry.getValue();
       }
@@ -99,27 +103,31 @@ public Object apply(Entry<?, ?> entry) {
   }
 
   @SuppressWarnings("unchecked")
-  static <K> Function<Entry<K, ?>, K> keyFunction() {
+  static <K extends @Nullable Object> Function<Entry<K, ?>, K> keyFunction() {
     return (Function) EntryFunction.KEY;
   }
 
   @SuppressWarnings("unchecked")
-  static <V> Function<Entry<?, V>, V> valueFunction() {
+  static <V extends @Nullable Object> Function<Entry<?, V>, V> valueFunction() {
     return (Function) EntryFunction.VALUE;
   }
 
-  static <K, V> Iterator<K> keyIterator(Iterator<Entry<K, V>> entryIterator) {
+  static <K extends @Nullable Object, V extends @Nullable Object> Iterator<K> keyIterator(
+      Iterator<Entry<K, V>> entryIterator) {
     return new TransformedIterator<Entry<K, V>, K>(entryIterator) {
       @Override
+      @ParametricNullness
       K transform(Entry<K, V> entry) {
         return entry.getKey();
       }
     };
   }
 
-  static <K, V> Iterator<V> valueIterator(Iterator<Entry<K, V>> entryIterator) {
+  static <K extends @Nullable Object, V extends @Nullable Object> Iterator<V> valueIterator(
+      Iterator<Entry<K, V>> entryIterator) {
     return new TransformedIterator<Entry<K, V>, V>(entryIterator) {
       @Override
+      @ParametricNullness
       V transform(Entry<K, V> entry) {
         return entry.getValue();
       }
@@ -173,13 +181,14 @@ public static <K extends Enum<K>, V> ImmutableMap<K, V> immutableEnumMap(
    *
    * <p><b>Note:</b> if {@code K} is an {@code enum} type, use {@link #newEnumMap} instead.
    *
-   * <p><b>Note for Java 7 and later:</b> this method is now unnecessary and should be treated as
-   * deprecated. Instead, use the {@code HashMap} constructor directly, taking advantage of the new
-   * <a href="http://goo.gl/iz2Wi">"diamond" syntax</a>.
+   * <p><b>Note:</b> this method is now unnecessary and should be treated as deprecated. Instead,
+   * use the {@code HashMap} constructor directly, taking advantage of <a
+   * href="http://goo.gl/iz2Wi">"diamond" syntax</a>.
    *
    * @return a new, empty {@code HashMap}
    */
-  public static <K, V> HashMap<K, V> newHashMap() {
+  public static <K extends @Nullable Object, V extends @Nullable Object>
+      HashMap<K, V> newHashMap() {
     return new HashMap<>();
   }
 
@@ -190,14 +199,15 @@ public static <K, V> HashMap<K, V> newHashMap() {
    *
    * <p><b>Note:</b> if {@code K} is an {@link Enum} type, use {@link #newEnumMap} instead.
    *
-   * <p><b>Note for Java 7 and later:</b> this method is now unnecessary and should be treated as
-   * deprecated. Instead, use the {@code HashMap} constructor directly, taking advantage of the new
-   * <a href="http://goo.gl/iz2Wi">"diamond" syntax</a>.
+   * <p><b>Note:</b> this method is now unnecessary and should be treated as deprecated. Instead,
+   * use the {@code HashMap} constructor directly, taking advantage of <a
+   * href="http://goo.gl/iz2Wi">"diamond" syntax</a>.
    *
    * @param map the mappings to be placed in the new map
    * @return a new {@code HashMap} initialized with the mappings from {@code map}
    */
-  public static <K, V> HashMap<K, V> newHashMap(Map<? extends K, ? extends V> map) {
+  public static <K extends @Nullable Object, V extends @Nullable Object> HashMap<K, V> newHashMap(
+      Map<? extends K, ? extends V> map) {
     return new HashMap<>(map);
   }
 
@@ -212,7 +222,8 @@ public static <K, V> HashMap<K, V> newHashMap(Map<? extends K, ? extends V> map)
    *     without resizing
    * @throws IllegalArgumentException if {@code expectedSize} is negative
    */
-  public static <K, V> HashMap<K, V> newHashMapWithExpectedSize(int expectedSize) {
+  public static <K extends @Nullable Object, V extends @Nullable Object>
+      HashMap<K, V> newHashMapWithExpectedSize(int expectedSize) {
     return new HashMap<>(capacity(expectedSize));
   }
 
@@ -239,13 +250,14 @@ static int capacity(int expectedSize) {
    *
    * <p><b>Note:</b> if mutability is not required, use {@link ImmutableMap#of()} instead.
    *
-   * <p><b>Note for Java 7 and later:</b> this method is now unnecessary and should be treated as
-   * deprecated. Instead, use the {@code LinkedHashMap} constructor directly, taking advantage of
-   * the new <a href="http://goo.gl/iz2Wi">"diamond" syntax</a>.
+   * <p><b>Note:</b> this method is now unnecessary and should be treated as deprecated. Instead,
+   * use the {@code LinkedHashMap} constructor directly, taking advantage of <a
+   * href="http://goo.gl/iz2Wi">"diamond" syntax</a>.
    *
    * @return a new, empty {@code LinkedHashMap}
    */
-  public static <K, V> LinkedHashMap<K, V> newLinkedHashMap() {
+  public static <K extends @Nullable Object, V extends @Nullable Object>
+      LinkedHashMap<K, V> newLinkedHashMap() {
     return new LinkedHashMap<>();
   }
 
@@ -255,14 +267,15 @@ public static <K, V> LinkedHashMap<K, V> newLinkedHashMap() {
    *
    * <p><b>Note:</b> if mutability is not required, use {@link ImmutableMap#copyOf(Map)} instead.
    *
-   * <p><b>Note for Java 7 and later:</b> this method is now unnecessary and should be treated as
-   * deprecated. Instead, use the {@code LinkedHashMap} constructor directly, taking advantage of
-   * the new <a href="http://goo.gl/iz2Wi">"diamond" syntax</a>.
+   * <p><b>Note:</b> this method is now unnecessary and should be treated as deprecated. Instead,
+   * use the {@code LinkedHashMap} constructor directly, taking advantage of <a
+   * href="http://goo.gl/iz2Wi">"diamond" syntax</a>.
    *
    * @param map the mappings to be placed in the new map
    * @return a new, {@code LinkedHashMap} initialized with the mappings from {@code map}
    */
-  public static <K, V> LinkedHashMap<K, V> newLinkedHashMap(Map<? extends K, ? extends V> map) {
+  public static <K extends @Nullable Object, V extends @Nullable Object>
+      LinkedHashMap<K, V> newLinkedHashMap(Map<? extends K, ? extends V> map) {
     return new LinkedHashMap<>(map);
   }
 
@@ -278,7 +291,8 @@ public static <K, V> LinkedHashMap<K, V> newLinkedHashMap(Map<? extends K, ? ext
    * @throws IllegalArgumentException if {@code expectedSize} is negative
    * @since 19.0
    */
-  public static <K, V> LinkedHashMap<K, V> newLinkedHashMapWithExpectedSize(int expectedSize) {
+  public static <K extends @Nullable Object, V extends @Nullable Object>
+      LinkedHashMap<K, V> newLinkedHashMapWithExpectedSize(int expectedSize) {
     return new LinkedHashMap<>(capacity(expectedSize));
   }
 
@@ -297,13 +311,13 @@ public static <K, V> ConcurrentMap<K, V> newConcurrentMap() {
    *
    * <p><b>Note:</b> if mutability is not required, use {@link ImmutableSortedMap#of()} instead.
    *
-   * <p><b>Note for Java 7 and later:</b> this method is now unnecessary and should be treated as
-   * deprecated. Instead, use the {@code TreeMap} constructor directly, taking advantage of the new
-   * <a href="http://goo.gl/iz2Wi">"diamond" syntax</a>.
+   * <p><b>Note:</b> this method is now unnecessary and should be treated as deprecated. Instead,
+   * use the {@code TreeMap} constructor directly, taking advantage of <a
+   * href="http://goo.gl/iz2Wi">"diamond" syntax</a>.
    *
    * @return a new, empty {@code TreeMap}
    */
-  public static <K extends Comparable, V> TreeMap<K, V> newTreeMap() {
+  public static <K extends Comparable, V extends @Nullable Object> TreeMap<K, V> newTreeMap() {
     return new TreeMap<>();
   }
 
@@ -314,16 +328,17 @@ public static <K extends Comparable, V> TreeMap<K, V> newTreeMap() {
    * <p><b>Note:</b> if mutability is not required, use {@link
    * ImmutableSortedMap#copyOfSorted(SortedMap)} instead.
    *
-   * <p><b>Note for Java 7 and later:</b> this method is now unnecessary and should be treated as
-   * deprecated. Instead, use the {@code TreeMap} constructor directly, taking advantage of the new
-   * <a href="http://goo.gl/iz2Wi">"diamond" syntax</a>.
+   * <p><b>Note:</b> this method is now unnecessary and should be treated as deprecated. Instead,
+   * use the {@code TreeMap} constructor directly, taking advantage of <a
+   * href="http://goo.gl/iz2Wi">"diamond" syntax</a>.
    *
    * @param map the sorted map whose mappings are to be placed in the new map and whose comparator
    *     is to be used to sort the new map
    * @return a new {@code TreeMap} initialized with the mappings from {@code map} and using the
    *     comparator of {@code map}
    */
-  public static <K, V> TreeMap<K, V> newTreeMap(SortedMap<K, ? extends V> map) {
+  public static <K extends @Nullable Object, V extends @Nullable Object> TreeMap<K, V> newTreeMap(
+      SortedMap<K, ? extends V> map) {
     return new TreeMap<>(map);
   }
 
@@ -333,15 +348,15 @@ public static <K, V> TreeMap<K, V> newTreeMap(SortedMap<K, ? extends V> map) {
    * <p><b>Note:</b> if mutability is not required, use {@code
    * ImmutableSortedMap.orderedBy(comparator).build()} instead.
    *
-   * <p><b>Note for Java 7 and later:</b> this method is now unnecessary and should be treated as
-   * deprecated. Instead, use the {@code TreeMap} constructor directly, taking advantage of the new
-   * <a href="http://goo.gl/iz2Wi">"diamond" syntax</a>.
+   * <p><b>Note:</b> this method is now unnecessary and should be treated as deprecated. Instead,
+   * use the {@code TreeMap} constructor directly, taking advantage of <a
+   * href="http://goo.gl/iz2Wi">"diamond" syntax</a>.
    *
    * @param comparator the comparator to sort the keys with
    * @return a new, empty {@code TreeMap}
    */
-  public static <C, K extends C, V> TreeMap<K, V> newTreeMap(
-      @NullableDecl Comparator<C> comparator) {
+  public static <C extends @Nullable Object, K extends C, V extends @Nullable Object>
+      TreeMap<K, V> newTreeMap(@CheckForNull Comparator<C> comparator) {
     // Ideally, the extra type parameter "C" shouldn't be necessary. It is a
     // work-around of a compiler type inference quirk that prevents the
     // following code from being compiled:
@@ -356,36 +371,39 @@ public static <C, K extends C, V> TreeMap<K, V> newTreeMap(
    * @param type the key type for this map
    * @return a new, empty {@code EnumMap}
    */
-  public static <K extends Enum<K>, V> EnumMap<K, V> newEnumMap(Class<K> type) {
+  public static <K extends Enum<K>, V extends @Nullable Object> EnumMap<K, V> newEnumMap(
+      Class<K> type) {
     return new EnumMap<>(checkNotNull(type));
   }
 
   /**
    * Creates an {@code EnumMap} with the same mappings as the specified map.
    *
-   * <p><b>Note for Java 7 and later:</b> this method is now unnecessary and should be treated as
-   * deprecated. Instead, use the {@code EnumMap} constructor directly, taking advantage of the new
-   * <a href="http://goo.gl/iz2Wi">"diamond" syntax</a>.
+   * <p><b>Note:</b> this method is now unnecessary and should be treated as deprecated. Instead,
+   * use the {@code EnumMap} constructor directly, taking advantage of <a
+   * href="http://goo.gl/iz2Wi">"diamond" syntax</a>.
    *
    * @param map the map from which to initialize this {@code EnumMap}
    * @return a new {@code EnumMap} initialized with the mappings from {@code map}
    * @throws IllegalArgumentException if {@code m} is not an {@code EnumMap} instance and contains
    *     no mappings
    */
-  public static <K extends Enum<K>, V> EnumMap<K, V> newEnumMap(Map<K, ? extends V> map) {
+  public static <K extends Enum<K>, V extends @Nullable Object> EnumMap<K, V> newEnumMap(
+      Map<K, ? extends V> map) {
     return new EnumMap<>(map);
   }
 
   /**
    * Creates an {@code IdentityHashMap} instance.
    *
-   * <p><b>Note for Java 7 and later:</b> this method is now unnecessary and should be treated as
-   * deprecated. Instead, use the {@code IdentityHashMap} constructor directly, taking advantage of
-   * the new <a href="http://goo.gl/iz2Wi">"diamond" syntax</a>.
+   * <p><b>Note:</b> this method is now unnecessary and should be treated as deprecated. Instead,
+   * use the {@code IdentityHashMap} constructor directly, taking advantage of <a
+   * href="http://goo.gl/iz2Wi">"diamond" syntax</a>.
    *
    * @return a new, empty {@code IdentityHashMap}
    */
-  public static <K, V> IdentityHashMap<K, V> newIdentityHashMap() {
+  public static <K extends @Nullable Object, V extends @Nullable Object>
+      IdentityHashMap<K, V> newIdentityHashMap() {
     return new IdentityHashMap<>();
   }
 
@@ -405,13 +423,27 @@ public static <K, V> IdentityHashMap<K, V> newIdentityHashMap() {
    * @return the difference between the two maps
    */
   @SuppressWarnings("unchecked")
-  public static <K, V> MapDifference<K, V> difference(
-      Map<? extends K, ? extends V> left, Map<? extends K, ? extends V> right) {
+  public static <K extends @Nullable Object, V extends @Nullable Object>
+      MapDifference<K, V> difference(
+          Map<? extends K, ? extends V> left, Map<? extends K, ? extends V> right) {
     if (left instanceof SortedMap) {
       SortedMap<K, ? extends V> sortedLeft = (SortedMap<K, ? extends V>) left;
       return difference(sortedLeft, right);
     }
-    return difference(left, right, Equivalence.equals());
+    /*
+     * This cast is safe: The Equivalence-accepting overload of difference() (which we call below)
+     * has a weird signature because Equivalence is itself a little weird. Still, we know that
+     * Equivalence.equals() can handle all inputs, and we know that the resulting MapDifference will
+     * contain only Ks and Vs (as opposed to possibly containing @Nullable objects even when K and V
+     * are *not* @Nullable).
+     *
+     * An alternative to suppressing the warning would be to inline the body of the other
+     * difference() method into this one.
+     */
+    @SuppressWarnings("nullness")
+    MapDifference<K, V> result =
+        (MapDifference<K, V>) difference(left, right, Equivalence.equals());
+    return result;
   }
 
   /**
@@ -428,7 +460,33 @@ public static <K, V> MapDifference<K, V> difference(
    * @return the difference between the two maps
    * @since 10.0
    */
-  public static <K, V> MapDifference<K, V> difference(
+  /*
+   * This method should really be annotated to accept maps with @Nullable value types. Fortunately,
+   * no existing Google callers appear to pass null values (much less pass null values *and* run a
+   * nullness checker).
+   *
+   * Still, if we decide that we want to make that work, we'd need to introduce a new type parameter
+   * for the Equivalence input type:
+   *
+   * <E, K extends @Nullable Object, V extends @Nullable E> ... difference(..., Equivalence<E> ...)
+   *
+   * Maybe we should, even though it will break source compatibility.
+   *
+   * Alternatively, this is a case in which it would be useful to be able to express Equivalence<?
+   * super @Nonnull T>).
+   *
+   * As things stand now, though, we have to either:
+   *
+   * - require non-null inputs so that we can guarantee non-null outputs
+   *
+   * - accept nullable inputs but force users to cope with nullable outputs
+   *
+   * And the non-null option is far more useful to existing users.
+   *
+   * (Vaguely related: Another thing we could consider is an overload that accepts a BiPredicate:
+   * https://github.com/google/guava/issues/3913)
+   */
+  public static <K extends @Nullable Object, V> MapDifference<K, V> difference(
       Map<? extends K, ? extends V> left,
       Map<? extends K, ? extends V> right,
       Equivalence<? super V> valueEquivalence) {
@@ -459,8 +517,9 @@ public static <K, V> MapDifference<K, V> difference(
    * @return the difference between the two maps
    * @since 11.0
    */
-  public static <K, V> SortedMapDifference<K, V> difference(
-      SortedMap<K, ? extends V> left, Map<? extends K, ? extends V> right) {
+  public static <K extends @Nullable Object, V extends @Nullable Object>
+      SortedMapDifference<K, V> difference(
+          SortedMap<K, ? extends V> left, Map<? extends K, ? extends V> right) {
     checkNotNull(left);
     checkNotNull(right);
     Comparator<? super K> comparator = orNaturalOrder(left.comparator());
@@ -469,11 +528,24 @@ public static <K, V> SortedMapDifference<K, V> difference(
     onlyOnRight.putAll(right); // will whittle it down
     SortedMap<K, V> onBoth = Maps.newTreeMap(comparator);
     SortedMap<K, MapDifference.ValueDifference<V>> differences = Maps.newTreeMap(comparator);
-    doDifference(left, right, Equivalence.equals(), onlyOnLeft, onlyOnRight, onBoth, differences);
+
+    /*
+     * V is a possibly nullable type, but we decided to declare Equivalence with a type parameter
+     * that is restricted to non-nullable types. Still, this code is safe: We made that decision
+     * about Equivalence not because Equivalence is null-hostile but because *every* Equivalence can
+     * handle null inputs -- and thus it would be meaningless for the type system to distinguish
+     * between "an Equivalence for nullable Foo" and "an Equivalence for non-nullable Foo."
+     *
+     * (And the unchecked cast is safe because Equivalence is contravariant.)
+     */
+    @SuppressWarnings({"nullness", "unchecked"})
+    Equivalence<V> equalsEquivalence = (Equivalence<V>) Equivalence.equals();
+
+    doDifference(left, right, equalsEquivalence, onlyOnLeft, onlyOnRight, onBoth, differences);
     return new SortedMapDifferenceImpl<>(onlyOnLeft, onlyOnRight, onBoth, differences);
   }
 
-  private static <K, V> void doDifference(
+  private static <K extends @Nullable Object, V extends @Nullable Object> void doDifference(
       Map<? extends K, ? extends V> left,
       Map<? extends K, ? extends V> right,
       Equivalence<? super V> valueEquivalence,
@@ -485,7 +557,17 @@ private static <K, V> void doDifference(
       K leftKey = entry.getKey();
       V leftValue = entry.getValue();
       if (right.containsKey(leftKey)) {
-        V rightValue = onlyOnRight.remove(leftKey);
+        /*
+         * The cast is safe because onlyOnRight contains all the keys of right.
+         *
+         * TODO(cpovirk): Consider checking onlyOnRight.containsKey instead of right.containsKey.
+         * That could change behavior if the input maps use different equivalence relations (and so
+         * a key that appears once in `right` might appear multiple times in `left`). We don't
+         * guarantee behavior in that case, anyway, and the current behavior is likely undesirable.
+         * So that's either a reason to feel free to change it or a reason to not bother thinking
+         * further about this.
+         */
+        V rightValue = uncheckedCastNullableTToT(onlyOnRight.remove(leftKey));
         if (valueEquivalence.equivalent(leftValue, rightValue)) {
           onBoth.put(leftKey, leftValue);
         } else {
@@ -497,7 +579,8 @@ private static <K, V> void doDifference(
     }
   }
 
-  private static <K, V> Map<K, V> unmodifiableMap(Map<K, ? extends V> map) {
+  private static <K extends @Nullable Object, V extends @Nullable Object> Map<K, V> unmodifiableMap(
+      Map<K, ? extends V> map) {
     if (map instanceof SortedMap) {
       return Collections.unmodifiableSortedMap((SortedMap<K, ? extends V>) map);
     } else {
@@ -505,7 +588,8 @@ private static <K, V> Map<K, V> unmodifiableMap(Map<K, ? extends V> map) {
     }
   }
 
-  static class MapDifferenceImpl<K, V> implements MapDifference<K, V> {
+  static class MapDifferenceImpl<K extends @Nullable Object, V extends @Nullable Object>
+      implements MapDifference<K, V> {
     final Map<K, V> onlyOnLeft;
     final Map<K, V> onlyOnRight;
     final Map<K, V> onBoth;
@@ -548,7 +632,7 @@ public Map<K, ValueDifference<V>> entriesDiffering() {
     }
 
     @Override
-    public boolean equals(Object object) {
+    public boolean equals(@CheckForNull Object object) {
       if (object == this) {
         return true;
       }
@@ -588,31 +672,35 @@ public String toString() {
     }
   }
 
-  static class ValueDifferenceImpl<V> implements MapDifference.ValueDifference<V> {
-    @NullableDecl private final V left;
-    @NullableDecl private final V right;
+  static class ValueDifferenceImpl<V extends @Nullable Object>
+      implements MapDifference.ValueDifference<V> {
+    @ParametricNullness private final V left;
+    @ParametricNullness private final V right;
 
-    static <V> ValueDifference<V> create(@NullableDecl V left, @NullableDecl V right) {
+    static <V extends @Nullable Object> ValueDifference<V> create(
+        @ParametricNullness V left, @ParametricNullness V right) {
       return new ValueDifferenceImpl<V>(left, right);
     }
 
-    private ValueDifferenceImpl(@NullableDecl V left, @NullableDecl V right) {
+    private ValueDifferenceImpl(@ParametricNullness V left, @ParametricNullness V right) {
       this.left = left;
       this.right = right;
     }
 
     @Override
+    @ParametricNullness
     public V leftValue() {
       return left;
     }
 
     @Override
+    @ParametricNullness
     public V rightValue() {
       return right;
     }
 
     @Override
-    public boolean equals(@NullableDecl Object object) {
+    public boolean equals(@CheckForNull Object object) {
       if (object instanceof MapDifference.ValueDifference) {
         MapDifference.ValueDifference<?> that = (MapDifference.ValueDifference<?>) object;
         return Objects.equal(this.left, that.leftValue())
@@ -632,8 +720,8 @@ public String toString() {
     }
   }
 
-  static class SortedMapDifferenceImpl<K, V> extends MapDifferenceImpl<K, V>
-      implements SortedMapDifference<K, V> {
+  static class SortedMapDifferenceImpl<K extends @Nullable Object, V extends @Nullable Object>
+      extends MapDifferenceImpl<K, V> implements SortedMapDifference<K, V> {
     SortedMapDifferenceImpl(
         SortedMap<K, V> onlyOnLeft,
         SortedMap<K, V> onlyOnRight,
@@ -669,7 +757,8 @@ public SortedMap<K, V> entriesOnlyOnRight() {
    * ugly type-casting in one place.
    */
   @SuppressWarnings("unchecked")
-  static <E> Comparator<? super E> orNaturalOrder(@NullableDecl Comparator<? super E> comparator) {
+  static <E extends @Nullable Object> Comparator<? super E> orNaturalOrder(
+      @CheckForNull Comparator<? super E> comparator) {
     if (comparator != null) { // can't use ? : because of javac bug 5080917
       return comparator;
     }
@@ -700,7 +789,8 @@ static <E> Comparator<? super E> orNaturalOrder(@NullableDecl Comparator<? super
    *
    * @since 14.0
    */
-  public static <K, V> Map<K, V> asMap(Set<K> set, Function<? super K, V> function) {
+  public static <K extends @Nullable Object, V extends @Nullable Object> Map<K, V> asMap(
+      Set<K> set, Function<? super K, V> function) {
     return new AsMapView<>(set, function);
   }
 
@@ -727,7 +817,8 @@ public static <K, V> Map<K, V> asMap(Set<K> set, Function<? super K, V> function
    *
    * @since 14.0
    */
-  public static <K, V> SortedMap<K, V> asMap(SortedSet<K> set, Function<? super K, V> function) {
+  public static <K extends @Nullable Object, V extends @Nullable Object> SortedMap<K, V> asMap(
+      SortedSet<K> set, Function<? super K, V> function) {
     return new SortedAsMapView<>(set, function);
   }
 
@@ -755,12 +846,13 @@ public static <K, V> SortedMap<K, V> asMap(SortedSet<K> set, Function<? super K,
    * @since 14.0
    */
   @GwtIncompatible // NavigableMap
-  public static <K, V> NavigableMap<K, V> asMap(
+  public static <K extends @Nullable Object, V extends @Nullable Object> NavigableMap<K, V> asMap(
       NavigableSet<K> set, Function<? super K, V> function) {
     return new NavigableAsMapView<>(set, function);
   }
 
-  private static class AsMapView<K, V> extends ViewCachingAbstractMap<K, V> {
+  private static class AsMapView<K extends @Nullable Object, V extends @Nullable Object>
+      extends ViewCachingAbstractMap<K, V> {
 
     private final Set<K> set;
     final Function<? super K, V> function;
@@ -790,12 +882,13 @@ public int size() {
     }
 
     @Override
-    public boolean containsKey(@NullableDecl Object key) {
+    public boolean containsKey(@CheckForNull Object key) {
       return backingSet().contains(key);
     }
 
     @Override
-    public V get(@NullableDecl Object key) {
+    @CheckForNull
+    public V get(@CheckForNull Object key) {
       if (Collections2.safeContains(backingSet(), key)) {
         @SuppressWarnings("unchecked") // unsafe, but Javadoc warns about it
         K k = (K) key;
@@ -806,7 +899,8 @@ public V get(@NullableDecl Object key) {
     }
 
     @Override
-    public V remove(@NullableDecl Object key) {
+    @CheckForNull
+    public V remove(@CheckForNull Object key) {
       if (backingSet().remove(key)) {
         @SuppressWarnings("unchecked") // unsafe, but Javadoc warns about it
         K k = (K) key;
@@ -839,17 +933,18 @@ public Iterator<Entry<K, V>> iterator() {
     }
   }
 
-  static <K, V> Iterator<Entry<K, V>> asMapEntryIterator(
-      Set<K> set, final Function<? super K, V> function) {
+  static <K extends @Nullable Object, V extends @Nullable Object>
+      Iterator<Entry<K, V>> asMapEntryIterator(Set<K> set, final Function<? super K, V> function) {
     return new TransformedIterator<K, Entry<K, V>>(set.iterator()) {
       @Override
-      Entry<K, V> transform(final K key) {
+      Entry<K, V> transform(@ParametricNullness final K key) {
         return immutableEntry(key, function.apply(key));
       }
     };
   }
 
-  private static class SortedAsMapView<K, V> extends AsMapView<K, V> implements SortedMap<K, V> {
+  private static class SortedAsMapView<K extends @Nullable Object, V extends @Nullable Object>
+      extends AsMapView<K, V> implements SortedMap<K, V> {
 
     SortedAsMapView(SortedSet<K> set, Function<? super K, V> function) {
       super(set, function);
@@ -861,6 +956,7 @@ SortedSet<K> backingSet() {
     }
 
     @Override
+    @CheckForNull
     public Comparator<? super K> comparator() {
       return backingSet().comparator();
     }
@@ -871,33 +967,37 @@ public Set<K> keySet() {
     }
 
     @Override
-    public SortedMap<K, V> subMap(K fromKey, K toKey) {
+    public SortedMap<K, V> subMap(@ParametricNullness K fromKey, @ParametricNullness K toKey) {
       return asMap(backingSet().subSet(fromKey, toKey), function);
     }
 
     @Override
-    public SortedMap<K, V> headMap(K toKey) {
+    public SortedMap<K, V> headMap(@ParametricNullness K toKey) {
       return asMap(backingSet().headSet(toKey), function);
     }
 
     @Override
-    public SortedMap<K, V> tailMap(K fromKey) {
+    public SortedMap<K, V> tailMap(@ParametricNullness K fromKey) {
       return asMap(backingSet().tailSet(fromKey), function);
     }
 
     @Override
+    @ParametricNullness
     public K firstKey() {
       return backingSet().first();
     }
 
     @Override
+    @ParametricNullness
     public K lastKey() {
       return backingSet().last();
     }
   }
 
   @GwtIncompatible // NavigableMap
-  private static final class NavigableAsMapView<K, V> extends AbstractNavigableMap<K, V> {
+  private static final class NavigableAsMapView<
+          K extends @Nullable Object, V extends @Nullable Object>
+      extends AbstractNavigableMap<K, V> {
     /*
      * Using AbstractNavigableMap is simpler than extending SortedAsMapView and rewriting all the
      * NavigableMap methods.
@@ -913,28 +1013,32 @@ private static final class NavigableAsMapView<K, V> extends AbstractNavigableMap
 
     @Override
     public NavigableMap<K, V> subMap(
-        K fromKey, boolean fromInclusive, K toKey, boolean toInclusive) {
+        @ParametricNullness K fromKey,
+        boolean fromInclusive,
+        @ParametricNullness K toKey,
+        boolean toInclusive) {
       return asMap(set.subSet(fromKey, fromInclusive, toKey, toInclusive), function);
     }
 
     @Override
-    public NavigableMap<K, V> headMap(K toKey, boolean inclusive) {
+    public NavigableMap<K, V> headMap(@ParametricNullness K toKey, boolean inclusive) {
       return asMap(set.headSet(toKey, inclusive), function);
     }
 
     @Override
-    public NavigableMap<K, V> tailMap(K fromKey, boolean inclusive) {
+    public NavigableMap<K, V> tailMap(@ParametricNullness K fromKey, boolean inclusive) {
       return asMap(set.tailSet(fromKey, inclusive), function);
     }
 
     @Override
+    @CheckForNull
     public Comparator<? super K> comparator() {
       return set.comparator();
     }
 
     @Override
-    @NullableDecl
-    public V get(@NullableDecl Object key) {
+    @CheckForNull
+    public V get(@CheckForNull Object key) {
       if (Collections2.safeContains(set, key)) {
         @SuppressWarnings("unchecked") // unsafe, but Javadoc warns about it
         K k = (K) key;
@@ -975,7 +1079,7 @@ public NavigableMap<K, V> descendingMap() {
     }
   }
 
-  private static <E> Set<E> removeOnlySet(final Set<E> set) {
+  private static <E extends @Nullable Object> Set<E> removeOnlySet(final Set<E> set) {
     return new ForwardingSet<E>() {
       @Override
       protected Set<E> delegate() {
@@ -983,7 +1087,7 @@ protected Set<E> delegate() {
       }
 
       @Override
-      public boolean add(E element) {
+      public boolean add(@ParametricNullness E element) {
         throw new UnsupportedOperationException();
       }
 
@@ -994,7 +1098,8 @@ public boolean addAll(Collection<? extends E> es) {
     };
   }
 
-  private static <E> SortedSet<E> removeOnlySortedSet(final SortedSet<E> set) {
+  private static <E extends @Nullable Object> SortedSet<E> removeOnlySortedSet(
+      final SortedSet<E> set) {
     return new ForwardingSortedSet<E>() {
       @Override
       protected SortedSet<E> delegate() {
@@ -1002,7 +1107,7 @@ protected SortedSet<E> delegate() {
       }
 
       @Override
-      public boolean add(E element) {
+      public boolean add(@ParametricNullness E element) {
         throw new UnsupportedOperationException();
       }
 
@@ -1012,24 +1117,26 @@ public boolean addAll(Collection<? extends E> es) {
       }
 
       @Override
-      public SortedSet<E> headSet(E toElement) {
+      public SortedSet<E> headSet(@ParametricNullness E toElement) {
         return removeOnlySortedSet(super.headSet(toElement));
       }
 
       @Override
-      public SortedSet<E> subSet(E fromElement, E toElement) {
+      public SortedSet<E> subSet(
+          @ParametricNullness E fromElement, @ParametricNullness E toElement) {
         return removeOnlySortedSet(super.subSet(fromElement, toElement));
       }
 
       @Override
-      public SortedSet<E> tailSet(E fromElement) {
+      public SortedSet<E> tailSet(@ParametricNullness E fromElement) {
         return removeOnlySortedSet(super.tailSet(fromElement));
       }
     };
   }
 
   @GwtIncompatible // NavigableSet
-  private static <E> NavigableSet<E> removeOnlyNavigableSet(final NavigableSet<E> set) {
+  private static <E extends @Nullable Object> NavigableSet<E> removeOnlyNavigableSet(
+      final NavigableSet<E> set) {
     return new ForwardingNavigableSet<E>() {
       @Override
       protected NavigableSet<E> delegate() {
@@ -1037,7 +1144,7 @@ protected NavigableSet<E> delegate() {
       }
 
       @Override
-      public boolean add(E element) {
+      public boolean add(@ParametricNullness E element) {
         throw new UnsupportedOperationException();
       }
 
@@ -1047,34 +1154,38 @@ public boolean addAll(Collection<? extends E> es) {
       }
 
       @Override
-      public SortedSet<E> headSet(E toElement) {
+      public SortedSet<E> headSet(@ParametricNullness E toElement) {
         return removeOnlySortedSet(super.headSet(toElement));
       }
 
       @Override
-      public NavigableSet<E> headSet(E toElement, boolean inclusive) {
+      public NavigableSet<E> headSet(@ParametricNullness E toElement, boolean inclusive) {
         return removeOnlyNavigableSet(super.headSet(toElement, inclusive));
       }
 
       @Override
-      public SortedSet<E> subSet(E fromElement, E toElement) {
+      public SortedSet<E> subSet(
+          @ParametricNullness E fromElement, @ParametricNullness E toElement) {
         return removeOnlySortedSet(super.subSet(fromElement, toElement));
       }
 
       @Override
       public NavigableSet<E> subSet(
-          E fromElement, boolean fromInclusive, E toElement, boolean toInclusive) {
+          @ParametricNullness E fromElement,
+          boolean fromInclusive,
+          @ParametricNullness E toElement,
+          boolean toInclusive) {
         return removeOnlyNavigableSet(
             super.subSet(fromElement, fromInclusive, toElement, toInclusive));
       }
 
       @Override
-      public SortedSet<E> tailSet(E fromElement) {
+      public SortedSet<E> tailSet(@ParametricNullness E fromElement) {
         return removeOnlySortedSet(super.tailSet(fromElement));
       }
 
       @Override
-      public NavigableSet<E> tailSet(E fromElement, boolean inclusive) {
+      public NavigableSet<E> tailSet(@ParametricNullness E fromElement, boolean inclusive) {
         return removeOnlyNavigableSet(super.tailSet(fromElement, inclusive));
       }
 
@@ -1122,13 +1233,13 @@ public static <K, V> ImmutableMap<K, V> toMap(
   public static <K, V> ImmutableMap<K, V> toMap(
       Iterator<K> keys, Function<? super K, V> valueFunction) {
     checkNotNull(valueFunction);
-    // Using LHM instead of a builder so as not to fail on duplicate keys
-    Map<K, V> builder = newLinkedHashMap();
+    ImmutableMap.Builder<K, V> builder = ImmutableMap.builder();
     while (keys.hasNext()) {
       K key = keys.next();
       builder.put(key, valueFunction.apply(key));
     }
-    return ImmutableMap.copyOf(builder);
+    // Using buildKeepingLast() so as not to fail on duplicate keys
+    return builder.buildKeepingLast();
   }
 
   /**
@@ -1205,7 +1316,7 @@ public static <K, V> ImmutableMap<K, V> uniqueIndex(
       builder.put(keyFunction.apply(value), value);
     }
     try {
-      return builder.build();
+      return builder.buildOrThrow();
     } catch (IllegalArgumentException duplicateKeys) {
       throw new IllegalArgumentException(
           duplicateKeys.getMessage()
@@ -1220,19 +1331,45 @@ public static <K, V> ImmutableMap<K, V> uniqueIndex(
    *
    * @param properties a {@code Properties} object to be converted
    * @return an immutable map containing all the entries in {@code properties}
-   * @throws ClassCastException if any key in {@code Properties} is not a {@code String}
-   * @throws NullPointerException if any key or value in {@code Properties} is null
+   * @throws ClassCastException if any key in {@code properties} is not a {@code String}
+   * @throws NullPointerException if any key or value in {@code properties} is null
    */
   @GwtIncompatible // java.util.Properties
   public static ImmutableMap<String, String> fromProperties(Properties properties) {
     ImmutableMap.Builder<String, String> builder = ImmutableMap.builder();
 
     for (Enumeration<?> e = properties.propertyNames(); e.hasMoreElements(); ) {
-      String key = (String) e.nextElement();
-      builder.put(key, properties.getProperty(key));
-    }
-
-    return builder.build();
+      /*
+       * requireNonNull is safe because propertyNames contains only non-null elements.
+       *
+       * Accordingly, we have it annotated as returning `Enumeration<? extends Object>` in our
+       * prototype checker's JDK. However, the checker still sees the return type as plain
+       * `Enumeration<?>`, probably because of one of the following two bugs (and maybe those two
+       * bugs are themselves just symptoms of the same underlying problem):
+       *
+       * https://github.com/typetools/checker-framework/issues/3030
+       *
+       * https://github.com/typetools/checker-framework/issues/3236
+       */
+      String key = (String) requireNonNull(e.nextElement());
+      /*
+       * requireNonNull is safe because the key came from propertyNames...
+       *
+       * ...except that it's possible for users to insert a string key with a non-string value, and
+       * in that case, getProperty *will* return null.
+       *
+       * TODO(b/192002623): Handle that case: Either:
+       *
+       * - Skip non-string keys and values entirely, as proposed in the linked bug.
+       *
+       * - Throw ClassCastException instead of NullPointerException, as documented in the current
+       *   Javadoc. (Note that we can't necessarily "just" change our call to `getProperty` to `get`
+       *   because `get` does not consult the default properties.)
+       */
+      builder.put(key, requireNonNull(properties.getProperty(key)));
+    }
+
+    return builder.buildOrThrow();
   }
 
   /**
@@ -1248,7 +1385,8 @@ public static ImmutableMap<String, String> fromProperties(Properties properties)
    * @param value the value to be associated with the returned entry
    */
   @GwtCompatible(serializable = true)
-  public static <K, V> Entry<K, V> immutableEntry(@NullableDecl K key, @NullableDecl V value) {
+  public static <K extends @Nullable Object, V extends @Nullable Object> Entry<K, V> immutableEntry(
+      @ParametricNullness K key, @ParametricNullness V value) {
     return new ImmutableEntry<>(key, value);
   }
 
@@ -1260,7 +1398,8 @@ public static <K, V> Entry<K, V> immutableEntry(@NullableDecl K key, @NullableDe
    * @param entrySet the entries for which to return an unmodifiable view
    * @return an unmodifiable view of the entries
    */
-  static <K, V> Set<Entry<K, V>> unmodifiableEntrySet(Set<Entry<K, V>> entrySet) {
+  static <K extends @Nullable Object, V extends @Nullable Object>
+      Set<Entry<K, V>> unmodifiableEntrySet(Set<Entry<K, V>> entrySet) {
     return new UnmodifiableEntrySet<>(Collections.unmodifiableSet(entrySet));
   }
 
@@ -1273,23 +1412,27 @@ static <K, V> Set<Entry<K, V>> unmodifiableEntrySet(Set<Entry<K, V>> entrySet) {
    * @param entry the entry for which to return an unmodifiable view
    * @return an unmodifiable view of the entry
    */
-  static <K, V> Entry<K, V> unmodifiableEntry(final Entry<? extends K, ? extends V> entry) {
+  static <K extends @Nullable Object, V extends @Nullable Object> Entry<K, V> unmodifiableEntry(
+      final Entry<? extends K, ? extends V> entry) {
     checkNotNull(entry);
     return new AbstractMapEntry<K, V>() {
       @Override
+      @ParametricNullness
       public K getKey() {
         return entry.getKey();
       }
 
       @Override
+      @ParametricNullness
       public V getValue() {
         return entry.getValue();
       }
     };
   }
 
-  static <K, V> UnmodifiableIterator<Entry<K, V>> unmodifiableEntryIterator(
-      final Iterator<Entry<K, V>> entryIterator) {
+  static <K extends @Nullable Object, V extends @Nullable Object>
+      UnmodifiableIterator<Entry<K, V>> unmodifiableEntryIterator(
+          final Iterator<Entry<K, V>> entryIterator) {
     return new UnmodifiableIterator<Entry<K, V>>() {
       @Override
       public boolean hasNext() {
@@ -1304,7 +1447,8 @@ public Entry<K, V> next() {
   }
 
   /** @see Multimaps#unmodifiableEntries */
-  static class UnmodifiableEntries<K, V> extends ForwardingCollection<Entry<K, V>> {
+  static class UnmodifiableEntries<K extends @Nullable Object, V extends @Nullable Object>
+      extends ForwardingCollection<Entry<K, V>> {
     private final Collection<Entry<K, V>> entries;
 
     UnmodifiableEntries(Collection<Entry<K, V>> entries) {
@@ -1325,18 +1469,26 @@ public Iterator<Entry<K, V>> iterator() {
 
     @Override
     public Object[] toArray() {
-      return standardToArray();
+      /*
+       * standardToArray returns `@Nullable Object[]` rather than `Object[]` but only because it can
+       * be used with collections that may contain null. This collection never contains nulls, so we
+       * can treat it as a plain `Object[]`.
+       */
+      @SuppressWarnings("nullness")
+      Object[] result = standardToArray();
+      return result;
     }
 
     @Override
-    public <T> T[] toArray(T[] array) {
+    @SuppressWarnings("nullness") // b/192354773 in our checker affects toArray declarations
+    public <T extends @Nullable Object> T[] toArray(T[] array) {
       return standardToArray(array);
     }
   }
 
   /** @see Maps#unmodifiableEntrySet(Set) */
-  static class UnmodifiableEntrySet<K, V> extends UnmodifiableEntries<K, V>
-      implements Set<Entry<K, V>> {
+  static class UnmodifiableEntrySet<K extends @Nullable Object, V extends @Nullable Object>
+      extends UnmodifiableEntries<K, V> implements Set<Entry<K, V>> {
     UnmodifiableEntrySet(Set<Entry<K, V>> entries) {
       super(entries);
     }
@@ -1344,7 +1496,7 @@ static class UnmodifiableEntrySet<K, V> extends UnmodifiableEntries<K, V>
     // See java.util.Collections.UnmodifiableEntrySet for details on attacks.
 
     @Override
-    public boolean equals(@NullableDecl Object object) {
+    public boolean equals(@CheckForNull Object object) {
       return Sets.equalsImpl(this, object);
     }
 
@@ -1392,7 +1544,7 @@ private static <X, Y> Y convert(BiMap<X, Y> bimap, X input) {
     }
 
     @Override
-    public boolean equals(@NullableDecl Object object) {
+    public boolean equals(@CheckForNull Object object) {
       if (object instanceof BiMapConverter) {
         BiMapConverter<?, ?> that = (BiMapConverter<?, ?>) object;
         return this.bimap.equals(that.bimap);
@@ -1443,7 +1595,8 @@ public String toString() {
    * @param bimap the bimap to be wrapped in a synchronized view
    * @return a synchronized view of the specified bimap
    */
-  public static <K, V> BiMap<K, V> synchronizedBiMap(BiMap<K, V> bimap) {
+  public static <K extends @Nullable Object, V extends @Nullable Object>
+      BiMap<K, V> synchronizedBiMap(BiMap<K, V> bimap) {
     return Synchronized.biMap(bimap, null);
   }
 
@@ -1458,19 +1611,20 @@ public static <K, V> BiMap<K, V> synchronizedBiMap(BiMap<K, V> bimap) {
    * @param bimap the bimap for which an unmodifiable view is to be returned
    * @return an unmodifiable view of the specified bimap
    */
-  public static <K, V> BiMap<K, V> unmodifiableBiMap(BiMap<? extends K, ? extends V> bimap) {
+  public static <K extends @Nullable Object, V extends @Nullable Object>
+      BiMap<K, V> unmodifiableBiMap(BiMap<? extends K, ? extends V> bimap) {
     return new UnmodifiableBiMap<>(bimap, null);
   }
 
   /** @see Maps#unmodifiableBiMap(BiMap) */
-  private static class UnmodifiableBiMap<K, V> extends ForwardingMap<K, V>
-      implements BiMap<K, V>, Serializable {
+  private static class UnmodifiableBiMap<K extends @Nullable Object, V extends @Nullable Object>
+      extends ForwardingMap<K, V> implements BiMap<K, V>, Serializable {
     final Map<K, V> unmodifiableMap;
     final BiMap<? extends K, ? extends V> delegate;
-    @RetainedWith @NullableDecl BiMap<V, K> inverse;
-    @NullableDecl transient Set<V> values;
+    @RetainedWith @CheckForNull BiMap<V, K> inverse;
+    @CheckForNull transient Set<V> values;
 
-    UnmodifiableBiMap(BiMap<? extends K, ? extends V> delegate, @NullableDecl BiMap<V, K> inverse) {
+    UnmodifiableBiMap(BiMap<? extends K, ? extends V> delegate, @CheckForNull BiMap<V, K> inverse) {
       unmodifiableMap = Collections.unmodifiableMap(delegate);
       this.delegate = delegate;
       this.inverse = inverse;
@@ -1482,7 +1636,8 @@ protected Map<K, V> delegate() {
     }
 
     @Override
-    public V forcePut(K key, V value) {
+    @CheckForNull
+    public V forcePut(@ParametricNullness K key, @ParametricNullness V value) {
       throw new UnsupportedOperationException();
     }
 
@@ -1536,8 +1691,9 @@ public Set<V> values() {
    * function} should be fast. To avoid lazy evaluation when the returned map doesn't need to be a
    * view, copy the returned map into a new map of your choosing.
    */
-  public static <K, V1, V2> Map<K, V2> transformValues(
-      Map<K, V1> fromMap, Function<? super V1, V2> function) {
+  public static <
+          K extends @Nullable Object, V1 extends @Nullable Object, V2 extends @Nullable Object>
+      Map<K, V2> transformValues(Map<K, V1> fromMap, Function<? super V1, V2> function) {
     return transformEntries(fromMap, asEntryTransformer(function));
   }
 
@@ -1577,8 +1733,10 @@ public static <K, V1, V2> Map<K, V2> transformValues(
    *
    * @since 11.0
    */
-  public static <K, V1, V2> SortedMap<K, V2> transformValues(
-      SortedMap<K, V1> fromMap, Function<? super V1, V2> function) {
+  public static <
+          K extends @Nullable Object, V1 extends @Nullable Object, V2 extends @Nullable Object>
+      SortedMap<K, V2> transformValues(
+          SortedMap<K, V1> fromMap, Function<? super V1, V2> function) {
     return transformEntries(fromMap, asEntryTransformer(function));
   }
 
@@ -1621,8 +1779,10 @@ public static <K, V1, V2> SortedMap<K, V2> transformValues(
    * @since 13.0
    */
   @GwtIncompatible // NavigableMap
-  public static <K, V1, V2> NavigableMap<K, V2> transformValues(
-      NavigableMap<K, V1> fromMap, Function<? super V1, V2> function) {
+  public static <
+          K extends @Nullable Object, V1 extends @Nullable Object, V2 extends @Nullable Object>
+      NavigableMap<K, V2> transformValues(
+          NavigableMap<K, V1> fromMap, Function<? super V1, V2> function) {
     return transformEntries(fromMap, asEntryTransformer(function));
   }
 
@@ -1673,8 +1833,10 @@ public static <K, V1, V2> NavigableMap<K, V2> transformValues(
    *
    * @since 7.0
    */
-  public static <K, V1, V2> Map<K, V2> transformEntries(
-      Map<K, V1> fromMap, EntryTransformer<? super K, ? super V1, V2> transformer) {
+  public static <
+          K extends @Nullable Object, V1 extends @Nullable Object, V2 extends @Nullable Object>
+      Map<K, V2> transformEntries(
+          Map<K, V1> fromMap, EntryTransformer<? super K, ? super V1, V2> transformer) {
     return new TransformedEntriesMap<>(fromMap, transformer);
   }
 
@@ -1725,8 +1887,10 @@ public static <K, V1, V2> Map<K, V2> transformEntries(
    *
    * @since 11.0
    */
-  public static <K, V1, V2> SortedMap<K, V2> transformEntries(
-      SortedMap<K, V1> fromMap, EntryTransformer<? super K, ? super V1, V2> transformer) {
+  public static <
+          K extends @Nullable Object, V1 extends @Nullable Object, V2 extends @Nullable Object>
+      SortedMap<K, V2> transformEntries(
+          SortedMap<K, V1> fromMap, EntryTransformer<? super K, ? super V1, V2> transformer) {
     return new TransformedEntriesSortedMap<>(fromMap, transformer);
   }
 
@@ -1779,8 +1943,10 @@ public static <K, V1, V2> SortedMap<K, V2> transformEntries(
    * @since 13.0
    */
   @GwtIncompatible // NavigableMap
-  public static <K, V1, V2> NavigableMap<K, V2> transformEntries(
-      NavigableMap<K, V1> fromMap, EntryTransformer<? super K, ? super V1, V2> transformer) {
+  public static <
+          K extends @Nullable Object, V1 extends @Nullable Object, V2 extends @Nullable Object>
+      NavigableMap<K, V2> transformEntries(
+          NavigableMap<K, V1> fromMap, EntryTransformer<? super K, ? super V1, V2> transformer) {
     return new TransformedEntriesNavigableMap<>(fromMap, transformer);
   }
 
@@ -1793,7 +1959,8 @@ public static <K, V1, V2> NavigableMap<K, V2> transformEntries(
    * @param <V2> the value type of the output entry
    * @since 7.0
    */
-  public interface EntryTransformer<K, V1, V2> {
+  public interface EntryTransformer<
+      K extends @Nullable Object, V1 extends @Nullable Object, V2 extends @Nullable Object> {
     /**
      * Determines an output value based on a key-value pair. This method is <i>generally
      * expected</i>, but not absolutely required, to have the following properties:
@@ -1808,38 +1975,43 @@ public interface EntryTransformer<K, V1, V2> {
      * @throws NullPointerException if the key or value is null and this transformer does not accept
      *     null arguments
      */
-    V2 transformEntry(@NullableDecl K key, @NullableDecl V1 value);
+    V2 transformEntry(@ParametricNullness K key, @ParametricNullness V1 value);
   }
 
   /** Views a function as an entry transformer that ignores the entry key. */
-  static <K, V1, V2> EntryTransformer<K, V1, V2> asEntryTransformer(
-      final Function<? super V1, V2> function) {
+  static <K extends @Nullable Object, V1 extends @Nullable Object, V2 extends @Nullable Object>
+      EntryTransformer<K, V1, V2> asEntryTransformer(final Function<? super V1, V2> function) {
     checkNotNull(function);
     return new EntryTransformer<K, V1, V2>() {
       @Override
-      public V2 transformEntry(K key, V1 value) {
+      @ParametricNullness
+      public V2 transformEntry(@ParametricNullness K key, @ParametricNullness V1 value) {
         return function.apply(value);
       }
     };
   }
 
-  static <K, V1, V2> Function<V1, V2> asValueToValueFunction(
-      final EntryTransformer<? super K, V1, V2> transformer, final K key) {
+  static <K extends @Nullable Object, V1 extends @Nullable Object, V2 extends @Nullable Object>
+      Function<V1, V2> asValueToValueFunction(
+          final EntryTransformer<? super K, V1, V2> transformer, @ParametricNullness final K key) {
     checkNotNull(transformer);
     return new Function<V1, V2>() {
       @Override
-      public V2 apply(@NullableDecl V1 v1) {
+      @ParametricNullness
+      public V2 apply(@ParametricNullness V1 v1) {
         return transformer.transformEntry(key, v1);
       }
     };
   }
 
   /** Views an entry transformer as a function from {@code Entry} to values. */
-  static <K, V1, V2> Function<Entry<K, V1>, V2> asEntryToValueFunction(
-      final EntryTransformer<? super K, ? super V1, V2> transformer) {
+  static <K extends @Nullable Object, V1 extends @Nullable Object, V2 extends @Nullable Object>
+      Function<Entry<K, V1>, V2> asEntryToValueFunction(
+          final EntryTransformer<? super K, ? super V1, V2> transformer) {
     checkNotNull(transformer);
     return new Function<Entry<K, V1>, V2>() {
       @Override
+      @ParametricNullness
       public V2 apply(Entry<K, V1> entry) {
         return transformer.transformEntry(entry.getKey(), entry.getValue());
       }
@@ -1847,17 +2019,20 @@ public V2 apply(Entry<K, V1> entry) {
   }
 
   /** Returns a view of an entry transformed by the specified transformer. */
-  static <V2, K, V1> Entry<K, V2> transformEntry(
-      final EntryTransformer<? super K, ? super V1, V2> transformer, final Entry<K, V1> entry) {
+  static <V2 extends @Nullable Object, K extends @Nullable Object, V1 extends @Nullable Object>
+      Entry<K, V2> transformEntry(
+          final EntryTransformer<? super K, ? super V1, V2> transformer, final Entry<K, V1> entry) {
     checkNotNull(transformer);
     checkNotNull(entry);
     return new AbstractMapEntry<K, V2>() {
       @Override
+      @ParametricNullness
       public K getKey() {
         return entry.getKey();
       }
 
       @Override
+      @ParametricNullness
       public V2 getValue() {
         return transformer.transformEntry(entry.getKey(), entry.getValue());
       }
@@ -1865,8 +2040,9 @@ public V2 getValue() {
   }
 
   /** Views an entry transformer as a function from entries to entries. */
-  static <K, V1, V2> Function<Entry<K, V1>, Entry<K, V2>> asEntryToEntryFunction(
-      final EntryTransformer<? super K, ? super V1, V2> transformer) {
+  static <K extends @Nullable Object, V1 extends @Nullable Object, V2 extends @Nullable Object>
+      Function<Entry<K, V1>, Entry<K, V2>> asEntryToEntryFunction(
+          final EntryTransformer<? super K, ? super V1, V2> transformer) {
     checkNotNull(transformer);
     return new Function<Entry<K, V1>, Entry<K, V2>>() {
       @Override
@@ -1876,7 +2052,9 @@ public Entry<K, V2> apply(final Entry<K, V1> entry) {
     };
   }
 
-  static class TransformedEntriesMap<K, V1, V2> extends IteratorBasedAbstractMap<K, V2> {
+  static class TransformedEntriesMap<
+          K extends @Nullable Object, V1 extends @Nullable Object, V2 extends @Nullable Object>
+      extends IteratorBasedAbstractMap<K, V2> {
     final Map<K, V1> fromMap;
     final EntryTransformer<? super K, ? super V1, V2> transformer;
 
@@ -1892,26 +2070,31 @@ public int size() {
     }
 
     @Override
-    public boolean containsKey(Object key) {
+    public boolean containsKey(@CheckForNull Object key) {
       return fromMap.containsKey(key);
     }
 
     // safe as long as the user followed the <b>Warning</b> in the javadoc
     @SuppressWarnings("unchecked")
     @Override
-    public V2 get(Object key) {
+    @CheckForNull
+    public V2 get(@CheckForNull Object key) {
       V1 value = fromMap.get(key);
-      return (value != null || fromMap.containsKey(key))
-          ? transformer.transformEntry((K) key, value)
-          : null;
+      if (value != null || fromMap.containsKey(key)) {
+        // The cast is safe because of the containsKey check.
+        return transformer.transformEntry((K) key, uncheckedCastNullableTToT(value));
+      }
+      return null;
     }
 
     // safe as long as the user followed the <b>Warning</b> in the javadoc
     @SuppressWarnings("unchecked")
     @Override
-    public V2 remove(Object key) {
+    @CheckForNull
+    public V2 remove(@CheckForNull Object key) {
       return fromMap.containsKey(key)
-          ? transformer.transformEntry((K) key, fromMap.remove(key))
+          // The cast is safe because of the containsKey check.
+          ? transformer.transformEntry((K) key, uncheckedCastNullableTToT(fromMap.remove(key)))
           : null;
     }
 
@@ -1937,8 +2120,9 @@ public Collection<V2> values() {
     }
   }
 
-  static class TransformedEntriesSortedMap<K, V1, V2> extends TransformedEntriesMap<K, V1, V2>
-      implements SortedMap<K, V2> {
+  static class TransformedEntriesSortedMap<
+          K extends @Nullable Object, V1 extends @Nullable Object, V2 extends @Nullable Object>
+      extends TransformedEntriesMap<K, V1, V2> implements SortedMap<K, V2> {
 
     protected SortedMap<K, V1> fromMap() {
       return (SortedMap<K, V1>) fromMap;
@@ -1950,38 +2134,42 @@ protected SortedMap<K, V1> fromMap() {
     }
 
     @Override
+    @CheckForNull
     public Comparator<? super K> comparator() {
       return fromMap().comparator();
     }
 
     @Override
+    @ParametricNullness
     public K firstKey() {
       return fromMap().firstKey();
     }
 
     @Override
-    public SortedMap<K, V2> headMap(K toKey) {
+    public SortedMap<K, V2> headMap(@ParametricNullness K toKey) {
       return transformEntries(fromMap().headMap(toKey), transformer);
     }
 
     @Override
+    @ParametricNullness
     public K lastKey() {
       return fromMap().lastKey();
     }
 
     @Override
-    public SortedMap<K, V2> subMap(K fromKey, K toKey) {
+    public SortedMap<K, V2> subMap(@ParametricNullness K fromKey, @ParametricNullness K toKey) {
       return transformEntries(fromMap().subMap(fromKey, toKey), transformer);
     }
 
     @Override
-    public SortedMap<K, V2> tailMap(K fromKey) {
+    public SortedMap<K, V2> tailMap(@ParametricNullness K fromKey) {
       return transformEntries(fromMap().tailMap(fromKey), transformer);
     }
   }
 
   @GwtIncompatible // NavigableMap
-  private static class TransformedEntriesNavigableMap<K, V1, V2>
+  private static class TransformedEntriesNavigableMap<
+          K extends @Nullable Object, V1 extends @Nullable Object, V2 extends @Nullable Object>
       extends TransformedEntriesSortedMap<K, V1, V2> implements NavigableMap<K, V2> {
 
     TransformedEntriesNavigableMap(
@@ -1990,12 +2178,14 @@ private static class TransformedEntriesNavigableMap<K, V1, V2>
     }
 
     @Override
-    public Entry<K, V2> ceilingEntry(K key) {
+    @CheckForNull
+    public Entry<K, V2> ceilingEntry(@ParametricNullness K key) {
       return transformEntry(fromMap().ceilingEntry(key));
     }
 
     @Override
-    public K ceilingKey(K key) {
+    @CheckForNull
+    public K ceilingKey(@ParametricNullness K key) {
       return fromMap().ceilingKey(key);
     }
 
@@ -2010,52 +2200,60 @@ public NavigableMap<K, V2> descendingMap() {
     }
 
     @Override
+    @CheckForNull
     public Entry<K, V2> firstEntry() {
       return transformEntry(fromMap().firstEntry());
     }
 
     @Override
-    public Entry<K, V2> floorEntry(K key) {
+    @CheckForNull
+    public Entry<K, V2> floorEntry(@ParametricNullness K key) {
       return transformEntry(fromMap().floorEntry(key));
     }
 
     @Override
-    public K floorKey(K key) {
+    @CheckForNull
+    public K floorKey(@ParametricNullness K key) {
       return fromMap().floorKey(key);
     }
 
     @Override
-    public NavigableMap<K, V2> headMap(K toKey) {
+    public NavigableMap<K, V2> headMap(@ParametricNullness K toKey) {
       return headMap(toKey, false);
     }
 
     @Override
-    public NavigableMap<K, V2> headMap(K toKey, boolean inclusive) {
+    public NavigableMap<K, V2> headMap(@ParametricNullness K toKey, boolean inclusive) {
       return transformEntries(fromMap().headMap(toKey, inclusive), transformer);
     }
 
     @Override
-    public Entry<K, V2> higherEntry(K key) {
+    @CheckForNull
+    public Entry<K, V2> higherEntry(@ParametricNullness K key) {
       return transformEntry(fromMap().higherEntry(key));
     }
 
     @Override
-    public K higherKey(K key) {
+    @CheckForNull
+    public K higherKey(@ParametricNullness K key) {
       return fromMap().higherKey(key);
     }
 
     @Override
+    @CheckForNull
     public Entry<K, V2> lastEntry() {
       return transformEntry(fromMap().lastEntry());
     }
 
     @Override
-    public Entry<K, V2> lowerEntry(K key) {
+    @CheckForNull
+    public Entry<K, V2> lowerEntry(@ParametricNullness K key) {
       return transformEntry(fromMap().lowerEntry(key));
     }
 
     @Override
-    public K lowerKey(K key) {
+    @CheckForNull
+    public K lowerKey(@ParametricNullness K key) {
       return fromMap().lowerKey(key);
     }
 
@@ -2065,39 +2263,44 @@ public NavigableSet<K> navigableKeySet() {
     }
 
     @Override
+    @CheckForNull
     public Entry<K, V2> pollFirstEntry() {
       return transformEntry(fromMap().pollFirstEntry());
     }
 
     @Override
+    @CheckForNull
     public Entry<K, V2> pollLastEntry() {
       return transformEntry(fromMap().pollLastEntry());
     }
 
     @Override
     public NavigableMap<K, V2> subMap(
-        K fromKey, boolean fromInclusive, K toKey, boolean toInclusive) {
+        @ParametricNullness K fromKey,
+        boolean fromInclusive,
+        @ParametricNullness K toKey,
+        boolean toInclusive) {
       return transformEntries(
           fromMap().subMap(fromKey, fromInclusive, toKey, toInclusive), transformer);
     }
 
     @Override
-    public NavigableMap<K, V2> subMap(K fromKey, K toKey) {
+    public NavigableMap<K, V2> subMap(@ParametricNullness K fromKey, @ParametricNullness K toKey) {
       return subMap(fromKey, true, toKey, false);
     }
 
     @Override
-    public NavigableMap<K, V2> tailMap(K fromKey) {
+    public NavigableMap<K, V2> tailMap(@ParametricNullness K fromKey) {
       return tailMap(fromKey, true);
     }
 
     @Override
-    public NavigableMap<K, V2> tailMap(K fromKey, boolean inclusive) {
+    public NavigableMap<K, V2> tailMap(@ParametricNullness K fromKey, boolean inclusive) {
       return transformEntries(fromMap().tailMap(fromKey, inclusive), transformer);
     }
 
-    @NullableDecl
-    private Entry<K, V2> transformEntry(@NullableDecl Entry<K, V1> entry) {
+    @CheckForNull
+    private Entry<K, V2> transformEntry(@CheckForNull Entry<K, V1> entry) {
       return (entry == null) ? null : Maps.transformEntry(transformer, entry);
     }
 
@@ -2107,11 +2310,13 @@ protected NavigableMap<K, V1> fromMap() {
     }
   }
 
-  static <K> Predicate<Entry<K, ?>> keyPredicateOnEntries(Predicate<? super K> keyPredicate) {
+  static <K extends @Nullable Object> Predicate<Entry<K, ?>> keyPredicateOnEntries(
+      Predicate<? super K> keyPredicate) {
     return compose(keyPredicate, Maps.<K>keyFunction());
   }
 
-  static <V> Predicate<Entry<?, V>> valuePredicateOnEntries(Predicate<? super V> valuePredicate) {
+  static <V extends @Nullable Object> Predicate<Entry<?, V>> valuePredicateOnEntries(
+      Predicate<? super V> valuePredicate) {
     return compose(valuePredicate, Maps.<V>valueFunction());
   }
 
@@ -2138,7 +2343,7 @@ static <V> Predicate<Entry<?, V>> valuePredicateOnEntries(Predicate<? super V> v
    * {@link Predicate#apply}. Do not provide a predicate such as {@code
    * Predicates.instanceOf(ArrayList.class)}, which is inconsistent with equals.
    */
-  public static <K, V> Map<K, V> filterKeys(
+  public static <K extends @Nullable Object, V extends @Nullable Object> Map<K, V> filterKeys(
       Map<K, V> unfiltered, final Predicate<? super K> keyPredicate) {
     checkNotNull(keyPredicate);
     Predicate<Entry<K, ?>> entryPredicate = keyPredicateOnEntries(keyPredicate);
@@ -2173,7 +2378,7 @@ public static <K, V> Map<K, V> filterKeys(
    *
    * @since 11.0
    */
-  public static <K, V> SortedMap<K, V> filterKeys(
+  public static <K extends @Nullable Object, V extends @Nullable Object> SortedMap<K, V> filterKeys(
       SortedMap<K, V> unfiltered, final Predicate<? super K> keyPredicate) {
     // TODO(lowasser): Return a subclass of Maps.FilteredKeyMap for slightly better
     // performance.
@@ -2207,8 +2412,9 @@ public static <K, V> SortedMap<K, V> filterKeys(
    * @since 14.0
    */
   @GwtIncompatible // NavigableMap
-  public static <K, V> NavigableMap<K, V> filterKeys(
-      NavigableMap<K, V> unfiltered, final Predicate<? super K> keyPredicate) {
+  public static <K extends @Nullable Object, V extends @Nullable Object>
+      NavigableMap<K, V> filterKeys(
+          NavigableMap<K, V> unfiltered, final Predicate<? super K> keyPredicate) {
     // TODO(lowasser): Return a subclass of Maps.FilteredKeyMap for slightly better
     // performance.
     return filterEntries(unfiltered, Maps.<K>keyPredicateOnEntries(keyPredicate));
@@ -2238,7 +2444,7 @@ public static <K, V> NavigableMap<K, V> filterKeys(
    *
    * @since 14.0
    */
-  public static <K, V> BiMap<K, V> filterKeys(
+  public static <K extends @Nullable Object, V extends @Nullable Object> BiMap<K, V> filterKeys(
       BiMap<K, V> unfiltered, final Predicate<? super K> keyPredicate) {
     checkNotNull(keyPredicate);
     return filterEntries(unfiltered, Maps.<K>keyPredicateOnEntries(keyPredicate));
@@ -2267,7 +2473,7 @@ public static <K, V> BiMap<K, V> filterKeys(
    * at {@link Predicate#apply}. Do not provide a predicate such as {@code
    * Predicates.instanceOf(ArrayList.class)}, which is inconsistent with equals.
    */
-  public static <K, V> Map<K, V> filterValues(
+  public static <K extends @Nullable Object, V extends @Nullable Object> Map<K, V> filterValues(
       Map<K, V> unfiltered, final Predicate<? super V> valuePredicate) {
     return filterEntries(unfiltered, Maps.<V>valuePredicateOnEntries(valuePredicate));
   }
@@ -2298,8 +2504,9 @@ public static <K, V> Map<K, V> filterValues(
    *
    * @since 11.0
    */
-  public static <K, V> SortedMap<K, V> filterValues(
-      SortedMap<K, V> unfiltered, final Predicate<? super V> valuePredicate) {
+  public static <K extends @Nullable Object, V extends @Nullable Object>
+      SortedMap<K, V> filterValues(
+          SortedMap<K, V> unfiltered, final Predicate<? super V> valuePredicate) {
     return filterEntries(unfiltered, Maps.<V>valuePredicateOnEntries(valuePredicate));
   }
 
@@ -2330,8 +2537,9 @@ public static <K, V> SortedMap<K, V> filterValues(
    * @since 14.0
    */
   @GwtIncompatible // NavigableMap
-  public static <K, V> NavigableMap<K, V> filterValues(
-      NavigableMap<K, V> unfiltered, final Predicate<? super V> valuePredicate) {
+  public static <K extends @Nullable Object, V extends @Nullable Object>
+      NavigableMap<K, V> filterValues(
+          NavigableMap<K, V> unfiltered, final Predicate<? super V> valuePredicate) {
     return filterEntries(unfiltered, Maps.<V>valuePredicateOnEntries(valuePredicate));
   }
 
@@ -2362,7 +2570,7 @@ public static <K, V> NavigableMap<K, V> filterValues(
    *
    * @since 14.0
    */
-  public static <K, V> BiMap<K, V> filterValues(
+  public static <K extends @Nullable Object, V extends @Nullable Object> BiMap<K, V> filterValues(
       BiMap<K, V> unfiltered, final Predicate<? super V> valuePredicate) {
     return filterEntries(unfiltered, Maps.<V>valuePredicateOnEntries(valuePredicate));
   }
@@ -2391,7 +2599,7 @@ public static <K, V> BiMap<K, V> filterValues(
    * <p><b>Warning:</b> {@code entryPredicate} must be <i>consistent with equals</i>, as documented
    * at {@link Predicate#apply}.
    */
-  public static <K, V> Map<K, V> filterEntries(
+  public static <K extends @Nullable Object, V extends @Nullable Object> Map<K, V> filterEntries(
       Map<K, V> unfiltered, Predicate<? super Entry<K, V>> entryPredicate) {
     checkNotNull(entryPredicate);
     return (unfiltered instanceof AbstractFilteredMap)
@@ -2425,8 +2633,9 @@ public static <K, V> Map<K, V> filterEntries(
    *
    * @since 11.0
    */
-  public static <K, V> SortedMap<K, V> filterEntries(
-      SortedMap<K, V> unfiltered, Predicate<? super Entry<K, V>> entryPredicate) {
+  public static <K extends @Nullable Object, V extends @Nullable Object>
+      SortedMap<K, V> filterEntries(
+          SortedMap<K, V> unfiltered, Predicate<? super Entry<K, V>> entryPredicate) {
     checkNotNull(entryPredicate);
     return (unfiltered instanceof FilteredEntrySortedMap)
         ? filterFiltered((FilteredEntrySortedMap<K, V>) unfiltered, entryPredicate)
@@ -2460,8 +2669,9 @@ public static <K, V> SortedMap<K, V> filterEntries(
    * @since 14.0
    */
   @GwtIncompatible // NavigableMap
-  public static <K, V> NavigableMap<K, V> filterEntries(
-      NavigableMap<K, V> unfiltered, Predicate<? super Entry<K, V>> entryPredicate) {
+  public static <K extends @Nullable Object, V extends @Nullable Object>
+      NavigableMap<K, V> filterEntries(
+          NavigableMap<K, V> unfiltered, Predicate<? super Entry<K, V>> entryPredicate) {
     checkNotNull(entryPredicate);
     return (unfiltered instanceof FilteredEntryNavigableMap)
         ? filterFiltered((FilteredEntryNavigableMap<K, V>) unfiltered, entryPredicate)
@@ -2495,7 +2705,7 @@ public static <K, V> NavigableMap<K, V> filterEntries(
    *
    * @since 14.0
    */
-  public static <K, V> BiMap<K, V> filterEntries(
+  public static <K extends @Nullable Object, V extends @Nullable Object> BiMap<K, V> filterEntries(
       BiMap<K, V> unfiltered, Predicate<? super Entry<K, V>> entryPredicate) {
     checkNotNull(unfiltered);
     checkNotNull(entryPredicate);
@@ -2508,7 +2718,7 @@ public static <K, V> BiMap<K, V> filterEntries(
    * Support {@code clear()}, {@code removeAll()}, and {@code retainAll()} when filtering a filtered
    * map.
    */
-  private static <K, V> Map<K, V> filterFiltered(
+  private static <K extends @Nullable Object, V extends @Nullable Object> Map<K, V> filterFiltered(
       AbstractFilteredMap<K, V> map, Predicate<? super Entry<K, V>> entryPredicate) {
     return new FilteredEntryMap<>(
         map.unfiltered, Predicates.<Entry<K, V>>and(map.predicate, entryPredicate));
@@ -2518,8 +2728,9 @@ private static <K, V> Map<K, V> filterFiltered(
    * Support {@code clear()}, {@code removeAll()}, and {@code retainAll()} when filtering a filtered
    * sorted map.
    */
-  private static <K, V> SortedMap<K, V> filterFiltered(
-      FilteredEntrySortedMap<K, V> map, Predicate<? super Entry<K, V>> entryPredicate) {
+  private static <K extends @Nullable Object, V extends @Nullable Object>
+      SortedMap<K, V> filterFiltered(
+          FilteredEntrySortedMap<K, V> map, Predicate<? super Entry<K, V>> entryPredicate) {
     Predicate<Entry<K, V>> predicate = Predicates.<Entry<K, V>>and(map.predicate, entryPredicate);
     return new FilteredEntrySortedMap<>(map.sortedMap(), predicate);
   }
@@ -2529,8 +2740,9 @@ private static <K, V> SortedMap<K, V> filterFiltered(
    * navigable map.
    */
   @GwtIncompatible // NavigableMap
-  private static <K, V> NavigableMap<K, V> filterFiltered(
-      FilteredEntryNavigableMap<K, V> map, Predicate<? super Entry<K, V>> entryPredicate) {
+  private static <K extends @Nullable Object, V extends @Nullable Object>
+      NavigableMap<K, V> filterFiltered(
+          FilteredEntryNavigableMap<K, V> map, Predicate<? super Entry<K, V>> entryPredicate) {
     Predicate<Entry<K, V>> predicate =
         Predicates.<Entry<K, V>>and(map.entryPredicate, entryPredicate);
     return new FilteredEntryNavigableMap<>(map.unfiltered, predicate);
@@ -2540,13 +2752,16 @@ private static <K, V> NavigableMap<K, V> filterFiltered(
    * Support {@code clear()}, {@code removeAll()}, and {@code retainAll()} when filtering a filtered
    * map.
    */
-  private static <K, V> BiMap<K, V> filterFiltered(
-      FilteredEntryBiMap<K, V> map, Predicate<? super Entry<K, V>> entryPredicate) {
+  private static <K extends @Nullable Object, V extends @Nullable Object>
+      BiMap<K, V> filterFiltered(
+          FilteredEntryBiMap<K, V> map, Predicate<? super Entry<K, V>> entryPredicate) {
     Predicate<Entry<K, V>> predicate = Predicates.<Entry<K, V>>and(map.predicate, entryPredicate);
     return new FilteredEntryBiMap<>(map.unfiltered(), predicate);
   }
 
-  private abstract static class AbstractFilteredMap<K, V> extends ViewCachingAbstractMap<K, V> {
+  private abstract static class AbstractFilteredMap<
+          K extends @Nullable Object, V extends @Nullable Object>
+      extends ViewCachingAbstractMap<K, V> {
     final Map<K, V> unfiltered;
     final Predicate<? super Entry<K, V>> predicate;
 
@@ -2555,16 +2770,17 @@ private abstract static class AbstractFilteredMap<K, V> extends ViewCachingAbstr
       this.predicate = predicate;
     }
 
-    boolean apply(@NullableDecl Object key, @NullableDecl V value) {
-      // This method is called only when the key is in the map, implying that
-      // key is a K.
-      @SuppressWarnings("unchecked")
+    boolean apply(@CheckForNull Object key, @ParametricNullness V value) {
+      // This method is called only when the key is in the map (or about to be added to the map),
+      // implying that key is a K.
+      @SuppressWarnings({"unchecked", "nullness"})
       K k = (K) key;
       return predicate.apply(Maps.immutableEntry(k, value));
     }
 
     @Override
-    public V put(K key, V value) {
+    @CheckForNull
+    public V put(@ParametricNullness K key, @ParametricNullness V value) {
       checkArgument(apply(key, value));
       return unfiltered.put(key, value);
     }
@@ -2578,12 +2794,13 @@ public void putAll(Map<? extends K, ? extends V> map) {
     }
 
     @Override
-    public boolean containsKey(Object key) {
+    public boolean containsKey(@CheckForNull Object key) {
       return unfiltered.containsKey(key) && apply(key, unfiltered.get(key));
     }
 
     @Override
-    public V get(Object key) {
+    @CheckForNull
+    public V get(@CheckForNull Object key) {
       V value = unfiltered.get(key);
       return ((value != null) && apply(key, value)) ? value : null;
     }
@@ -2594,7 +2811,8 @@ public boolean isEmpty() {
     }
 
     @Override
-    public V remove(Object key) {
+    @CheckForNull
+    public V remove(@CheckForNull Object key) {
       return containsKey(key) ? unfiltered.remove(key) : null;
     }
 
@@ -2604,7 +2822,9 @@ Collection<V> createValues() {
     }
   }
 
-  private static final class FilteredMapValues<K, V> extends Maps.Values<K, V> {
+  private static final class FilteredMapValues<
+          K extends @Nullable Object, V extends @Nullable Object>
+      extends Maps.Values<K, V> {
     final Map<K, V> unfiltered;
     final Predicate<? super Entry<K, V>> predicate;
 
@@ -2616,7 +2836,7 @@ private static final class FilteredMapValues<K, V> extends Maps.Values<K, V> {
     }
 
     @Override
-    public boolean remove(Object o) {
+    public boolean remove(@CheckForNull Object o) {
       Iterator<Entry<K, V>> entryItr = unfiltered.entrySet().iterator();
       while (entryItr.hasNext()) {
         Entry<K, V> entry = entryItr.next();
@@ -2657,18 +2877,20 @@ public boolean retainAll(Collection<?> collection) {
     }
 
     @Override
-    public Object[] toArray() {
+    public @Nullable Object[] toArray() {
       // creating an ArrayList so filtering happens once
       return Lists.newArrayList(iterator()).toArray();
     }
 
     @Override
-    public <T> T[] toArray(T[] array) {
+    @SuppressWarnings("nullness") // b/192354773 in our checker affects toArray declarations
+    public <T extends @Nullable Object> T[] toArray(T[] array) {
       return Lists.newArrayList(iterator()).toArray(array);
     }
   }
 
-  private static class FilteredKeyMap<K, V> extends AbstractFilteredMap<K, V> {
+  private static class FilteredKeyMap<K extends @Nullable Object, V extends @Nullable Object>
+      extends AbstractFilteredMap<K, V> {
     final Predicate<? super K> keyPredicate;
 
     FilteredKeyMap(
@@ -2693,12 +2915,13 @@ Set<K> createKeySet() {
     // that key is a K.
     @Override
     @SuppressWarnings("unchecked")
-    public boolean containsKey(Object key) {
+    public boolean containsKey(@CheckForNull Object key) {
       return unfiltered.containsKey(key) && keyPredicate.apply((K) key);
     }
   }
 
-  static class FilteredEntryMap<K, V> extends AbstractFilteredMap<K, V> {
+  static class FilteredEntryMap<K extends @Nullable Object, V extends @Nullable Object>
+      extends AbstractFilteredMap<K, V> {
     /**
      * Entries in this set satisfy the predicate, but they don't validate the input to {@code
      * Entry.setValue()}.
@@ -2734,7 +2957,8 @@ protected Entry<K, V> delegate() {
               }
 
               @Override
-              public V setValue(V newValue) {
+              @ParametricNullness
+              public V setValue(@ParametricNullness V newValue) {
                 checkArgument(apply(getKey(), newValue));
                 return super.setValue(newValue);
               }
@@ -2749,7 +2973,7 @@ Set<K> createKeySet() {
       return new KeySet();
     }
 
-    static <K, V> boolean removeAllKeys(
+    static <K extends @Nullable Object, V extends @Nullable Object> boolean removeAllKeys(
         Map<K, V> map, Predicate<? super Entry<K, V>> entryPredicate, Collection<?> keyCollection) {
       Iterator<Entry<K, V>> entryItr = map.entrySet().iterator();
       boolean result = false;
@@ -2763,7 +2987,7 @@ static <K, V> boolean removeAllKeys(
       return result;
     }
 
-    static <K, V> boolean retainAllKeys(
+    static <K extends @Nullable Object, V extends @Nullable Object> boolean retainAllKeys(
         Map<K, V> map, Predicate<? super Entry<K, V>> entryPredicate, Collection<?> keyCollection) {
       Iterator<Entry<K, V>> entryItr = map.entrySet().iterator();
       boolean result = false;
@@ -2784,7 +3008,7 @@ class KeySet extends Maps.KeySet<K, V> {
       }
 
       @Override
-      public boolean remove(Object o) {
+      public boolean remove(@CheckForNull Object o) {
         if (containsKey(o)) {
           unfiltered.remove(o);
           return true;
@@ -2803,20 +3027,22 @@ public boolean retainAll(Collection<?> collection) {
       }
 
       @Override
-      public Object[] toArray() {
+      public @Nullable Object[] toArray() {
         // creating an ArrayList so filtering happens once
         return Lists.newArrayList(iterator()).toArray();
       }
 
       @Override
-      public <T> T[] toArray(T[] array) {
+      @SuppressWarnings("nullness") // b/192354773 in our checker affects toArray declarations
+      public <T extends @Nullable Object> T[] toArray(T[] array) {
         return Lists.newArrayList(iterator()).toArray(array);
       }
     }
   }
 
-  private static class FilteredEntrySortedMap<K, V> extends FilteredEntryMap<K, V>
-      implements SortedMap<K, V> {
+  private static class FilteredEntrySortedMap<
+          K extends @Nullable Object, V extends @Nullable Object>
+      extends FilteredEntryMap<K, V> implements SortedMap<K, V> {
 
     FilteredEntrySortedMap(
         SortedMap<K, V> unfiltered, Predicate<? super Entry<K, V>> entryPredicate) {
@@ -2840,54 +3066,62 @@ SortedSet<K> createKeySet() {
     @WeakOuter
     class SortedKeySet extends KeySet implements SortedSet<K> {
       @Override
+      @CheckForNull
       public Comparator<? super K> comparator() {
         return sortedMap().comparator();
       }
 
       @Override
-      public SortedSet<K> subSet(K fromElement, K toElement) {
+      public SortedSet<K> subSet(
+          @ParametricNullness K fromElement, @ParametricNullness K toElement) {
         return (SortedSet<K>) subMap(fromElement, toElement).keySet();
       }
 
       @Override
-      public SortedSet<K> headSet(K toElement) {
+      public SortedSet<K> headSet(@ParametricNullness K toElement) {
         return (SortedSet<K>) headMap(toElement).keySet();
       }
 
       @Override
-      public SortedSet<K> tailSet(K fromElement) {
+      public SortedSet<K> tailSet(@ParametricNullness K fromElement) {
         return (SortedSet<K>) tailMap(fromElement).keySet();
       }
 
       @Override
+      @ParametricNullness
       public K first() {
         return firstKey();
       }
 
       @Override
+      @ParametricNullness
       public K last() {
         return lastKey();
       }
     }
 
     @Override
+    @CheckForNull
     public Comparator<? super K> comparator() {
       return sortedMap().comparator();
     }
 
     @Override
+    @ParametricNullness
     public K firstKey() {
       // correctly throws NoSuchElementException when filtered map is empty.
       return keySet().iterator().next();
     }
 
     @Override
+    @ParametricNullness
     public K lastKey() {
       SortedMap<K, V> headMap = sortedMap();
       while (true) {
         // correctly throws NoSuchElementException when filtered map is empty.
         K key = headMap.lastKey();
-        if (apply(key, unfiltered.get(key))) {
+        // The cast is safe because the key is taken from the map.
+        if (apply(key, uncheckedCastNullableTToT(unfiltered.get(key)))) {
           return key;
         }
         headMap = sortedMap().headMap(key);
@@ -2895,23 +3129,25 @@ public K lastKey() {
     }
 
     @Override
-    public SortedMap<K, V> headMap(K toKey) {
+    public SortedMap<K, V> headMap(@ParametricNullness K toKey) {
       return new FilteredEntrySortedMap<>(sortedMap().headMap(toKey), predicate);
     }
 
     @Override
-    public SortedMap<K, V> subMap(K fromKey, K toKey) {
+    public SortedMap<K, V> subMap(@ParametricNullness K fromKey, @ParametricNullness K toKey) {
       return new FilteredEntrySortedMap<>(sortedMap().subMap(fromKey, toKey), predicate);
     }
 
     @Override
-    public SortedMap<K, V> tailMap(K fromKey) {
+    public SortedMap<K, V> tailMap(@ParametricNullness K fromKey) {
       return new FilteredEntrySortedMap<>(sortedMap().tailMap(fromKey), predicate);
     }
   }
 
   @GwtIncompatible // NavigableMap
-  private static class FilteredEntryNavigableMap<K, V> extends AbstractNavigableMap<K, V> {
+  private static class FilteredEntryNavigableMap<
+          K extends @Nullable Object, V extends @Nullable Object>
+      extends AbstractNavigableMap<K, V> {
     /*
      * It's less code to extend AbstractNavigableMap and forward the filtering logic to
      * FilteredEntryMap than to extend FilteredEntrySortedMap and reimplement all the NavigableMap
@@ -2930,6 +3166,7 @@ private static class FilteredEntryNavigableMap<K, V> extends AbstractNavigableMa
     }
 
     @Override
+    @CheckForNull
     public Comparator<? super K> comparator() {
       return unfiltered.comparator();
     }
@@ -2975,23 +3212,25 @@ public boolean isEmpty() {
     }
 
     @Override
-    @NullableDecl
-    public V get(@NullableDecl Object key) {
+    @CheckForNull
+    public V get(@CheckForNull Object key) {
       return filteredDelegate.get(key);
     }
 
     @Override
-    public boolean containsKey(@NullableDecl Object key) {
+    public boolean containsKey(@CheckForNull Object key) {
       return filteredDelegate.containsKey(key);
     }
 
     @Override
-    public V put(K key, V value) {
+    @CheckForNull
+    public V put(@ParametricNullness K key, @ParametricNullness V value) {
       return filteredDelegate.put(key, value);
     }
 
     @Override
-    public V remove(@NullableDecl Object key) {
+    @CheckForNull
+    public V remove(@CheckForNull Object key) {
       return filteredDelegate.remove(key);
     }
 
@@ -3011,11 +3250,13 @@ public Set<Entry<K, V>> entrySet() {
     }
 
     @Override
+    @CheckForNull
     public Entry<K, V> pollFirstEntry() {
       return Iterables.removeFirstMatching(unfiltered.entrySet(), entryPredicate);
     }
 
     @Override
+    @CheckForNull
     public Entry<K, V> pollLastEntry() {
       return Iterables.removeFirstMatching(unfiltered.descendingMap().entrySet(), entryPredicate);
     }
@@ -3027,28 +3268,32 @@ public NavigableMap<K, V> descendingMap() {
 
     @Override
     public NavigableMap<K, V> subMap(
-        K fromKey, boolean fromInclusive, K toKey, boolean toInclusive) {
+        @ParametricNullness K fromKey,
+        boolean fromInclusive,
+        @ParametricNullness K toKey,
+        boolean toInclusive) {
       return filterEntries(
           unfiltered.subMap(fromKey, fromInclusive, toKey, toInclusive), entryPredicate);
     }
 
     @Override
-    public NavigableMap<K, V> headMap(K toKey, boolean inclusive) {
+    public NavigableMap<K, V> headMap(@ParametricNullness K toKey, boolean inclusive) {
       return filterEntries(unfiltered.headMap(toKey, inclusive), entryPredicate);
     }
 
     @Override
-    public NavigableMap<K, V> tailMap(K fromKey, boolean inclusive) {
+    public NavigableMap<K, V> tailMap(@ParametricNullness K fromKey, boolean inclusive) {
       return filterEntries(unfiltered.tailMap(fromKey, inclusive), entryPredicate);
     }
   }
 
-  static final class FilteredEntryBiMap<K, V> extends FilteredEntryMap<K, V>
-      implements BiMap<K, V> {
+  static final class FilteredEntryBiMap<K extends @Nullable Object, V extends @Nullable Object>
+      extends FilteredEntryMap<K, V> implements BiMap<K, V> {
     @RetainedWith private final BiMap<V, K> inverse;
 
-    private static <K, V> Predicate<Entry<V, K>> inversePredicate(
-        final Predicate<? super Entry<K, V>> forwardPredicate) {
+    private static <K extends @Nullable Object, V extends @Nullable Object>
+        Predicate<Entry<V, K>> inversePredicate(
+            final Predicate<? super Entry<K, V>> forwardPredicate) {
       return new Predicate<Entry<V, K>>() {
         @Override
         public boolean apply(Entry<V, K> input) {
@@ -3074,7 +3319,8 @@ BiMap<K, V> unfiltered() {
     }
 
     @Override
-    public V forcePut(@NullableDecl K key, @NullableDecl V value) {
+    @CheckForNull
+    public V forcePut(@ParametricNullness K key, @ParametricNullness V value) {
       checkArgument(apply(key, value));
       return unfiltered().forcePut(key, value);
     }
@@ -3109,8 +3355,8 @@ public Set<V> values() {
    * @since 12.0
    */
   @GwtIncompatible // NavigableMap
-  public static <K, V> NavigableMap<K, V> unmodifiableNavigableMap(
-      NavigableMap<K, ? extends V> map) {
+  public static <K extends @Nullable Object, V extends @Nullable Object>
+      NavigableMap<K, V> unmodifiableNavigableMap(NavigableMap<K, ? extends V> map) {
     checkNotNull(map);
     if (map instanceof UnmodifiableNavigableMap) {
       @SuppressWarnings("unchecked") // covariant
@@ -3121,14 +3367,15 @@ public static <K, V> NavigableMap<K, V> unmodifiableNavigableMap(
     }
   }
 
-  @NullableDecl
-  private static <K, V> Entry<K, V> unmodifiableOrNull(@NullableDecl Entry<K, ? extends V> entry) {
+  @CheckForNull
+  private static <K extends @Nullable Object, V extends @Nullable Object>
+      Entry<K, V> unmodifiableOrNull(@CheckForNull Entry<K, ? extends V> entry) {
     return (entry == null) ? null : Maps.unmodifiableEntry(entry);
   }
 
   @GwtIncompatible // NavigableMap
-  static class UnmodifiableNavigableMap<K, V> extends ForwardingSortedMap<K, V>
-      implements NavigableMap<K, V>, Serializable {
+  static class UnmodifiableNavigableMap<K extends @Nullable Object, V extends @Nullable Object>
+      extends ForwardingSortedMap<K, V> implements NavigableMap<K, V>, Serializable {
     private final NavigableMap<K, ? extends V> delegate;
 
     UnmodifiableNavigableMap(NavigableMap<K, ? extends V> delegate) {
@@ -3147,66 +3394,78 @@ protected SortedMap<K, V> delegate() {
     }
 
     @Override
-    public Entry<K, V> lowerEntry(K key) {
+    @CheckForNull
+    public Entry<K, V> lowerEntry(@ParametricNullness K key) {
       return unmodifiableOrNull(delegate.lowerEntry(key));
     }
 
     @Override
-    public K lowerKey(K key) {
+    @CheckForNull
+    public K lowerKey(@ParametricNullness K key) {
       return delegate.lowerKey(key);
     }
 
     @Override
-    public Entry<K, V> floorEntry(K key) {
+    @CheckForNull
+    public Entry<K, V> floorEntry(@ParametricNullness K key) {
       return unmodifiableOrNull(delegate.floorEntry(key));
     }
 
     @Override
-    public K floorKey(K key) {
+    @CheckForNull
+    public K floorKey(@ParametricNullness K key) {
       return delegate.floorKey(key);
     }
 
     @Override
-    public Entry<K, V> ceilingEntry(K key) {
+    @CheckForNull
+    public Entry<K, V> ceilingEntry(@ParametricNullness K key) {
       return unmodifiableOrNull(delegate.ceilingEntry(key));
     }
 
     @Override
-    public K ceilingKey(K key) {
+    @CheckForNull
+    public K ceilingKey(@ParametricNullness K key) {
       return delegate.ceilingKey(key);
     }
 
     @Override
-    public Entry<K, V> higherEntry(K key) {
+    @CheckForNull
+    public Entry<K, V> higherEntry(@ParametricNullness K key) {
       return unmodifiableOrNull(delegate.higherEntry(key));
     }
 
     @Override
-    public K higherKey(K key) {
+    @CheckForNull
+    public K higherKey(@ParametricNullness K key) {
       return delegate.higherKey(key);
     }
 
     @Override
+    @CheckForNull
     public Entry<K, V> firstEntry() {
       return unmodifiableOrNull(delegate.firstEntry());
     }
 
     @Override
+    @CheckForNull
     public Entry<K, V> lastEntry() {
       return unmodifiableOrNull(delegate.lastEntry());
     }
 
     @Override
+    @CheckForNull
     public final Entry<K, V> pollFirstEntry() {
       throw new UnsupportedOperationException();
     }
 
     @Override
+    @CheckForNull
     public final Entry<K, V> pollLastEntry() {
       throw new UnsupportedOperationException();
     }
 
-    @NullableDecl private transient UnmodifiableNavigableMap<K, V> descendingMap;
+    @CheckForNull private transient UnmodifiableNavigableMap<K, V> descendingMap;
 
     @Override
     public NavigableMap<K, V> descendingMap() {
@@ -3232,34 +3491,37 @@ public NavigableSet<K> descendingKeySet() {
     }
 
     @Override
-    public SortedMap<K, V> subMap(K fromKey, K toKey) {
+    public SortedMap<K, V> subMap(@ParametricNullness K fromKey, @ParametricNullness K toKey) {
       return subMap(fromKey, true, toKey, false);
     }
 
     @Override
     public NavigableMap<K, V> subMap(
-        K fromKey, boolean fromInclusive, K toKey, boolean toInclusive) {
+        @ParametricNullness K fromKey,
+        boolean fromInclusive,
+        @ParametricNullness K toKey,
+        boolean toInclusive) {
       return Maps.unmodifiableNavigableMap(
           delegate.subMap(fromKey, fromInclusive, toKey, toInclusive));
     }
 
     @Override
-    public SortedMap<K, V> headMap(K toKey) {
+    public SortedMap<K, V> headMap(@ParametricNullness K toKey) {
       return headMap(toKey, false);
     }
 
     @Override
-    public NavigableMap<K, V> headMap(K toKey, boolean inclusive) {
+    public NavigableMap<K, V> headMap(@ParametricNullness K toKey, boolean inclusive) {
       return Maps.unmodifiableNavigableMap(delegate.headMap(toKey, inclusive));
     }
 
     @Override
-    public SortedMap<K, V> tailMap(K fromKey) {
+    public SortedMap<K, V> tailMap(@ParametricNullness K fromKey) {
       return tailMap(fromKey, true);
     }
 
     @Override
-    public NavigableMap<K, V> tailMap(K fromKey, boolean inclusive) {
+    public NavigableMap<K, V> tailMap(@ParametricNullness K fromKey, boolean inclusive) {
       return Maps.unmodifiableNavigableMap(delegate.tailMap(fromKey, inclusive));
     }
   }
@@ -3314,8 +3576,8 @@ public NavigableMap<K, V> tailMap(K fromKey, boolean inclusive) {
    * @since 13.0
    */
   @GwtIncompatible // NavigableMap
-  public static <K, V> NavigableMap<K, V> synchronizedNavigableMap(
-      NavigableMap<K, V> navigableMap) {
+  public static <K extends @Nullable Object, V extends @Nullable Object>
+      NavigableMap<K, V> synchronizedNavigableMap(NavigableMap<K, V> navigableMap) {
     return Synchronized.navigableMap(navigableMap);
   }
 
@@ -3324,14 +3586,16 @@ public static <K, V> NavigableMap<K, V> synchronizedNavigableMap(
    * entrySet views.
    */
   @GwtCompatible
-  abstract static class ViewCachingAbstractMap<K, V> extends AbstractMap<K, V> {
+  abstract static class ViewCachingAbstractMap<
+          K extends @Nullable Object, V extends @Nullable Object>
+      extends AbstractMap<K, V> {
     /**
      * Creates the entry set to be returned by {@link #entrySet()}. This method is invoked at most
      * once on a given map, at the time when {@code entrySet} is first called.
      */
     abstract Set<Entry<K, V>> createEntrySet();
 
-    @NullableDecl private transient Set<Entry<K, V>> entrySet;
+    @CheckForNull private transient Set<Entry<K, V>> entrySet;
 
     @Override
     public Set<Entry<K, V>> entrySet() {
@@ -3339,7 +3603,7 @@ public Set<Entry<K, V>> entrySet() {
       return (result == null) ? entrySet = createEntrySet() : result;
     }
 
-    @NullableDecl private transient Set<K> keySet;
+    @CheckForNull private transient Set<K> keySet;
 
     @Override
     public Set<K> keySet() {
@@ -3351,7 +3615,7 @@ Set<K> createKeySet() {
       return new KeySet<>(this);
     }
 
-    @NullableDecl private transient Collection<V> values;
+    @CheckForNull private transient Collection<V> values;
 
     @Override
     public Collection<V> values() {
@@ -3364,7 +3628,9 @@ Collection<V> createValues() {
     }
   }
 
-  abstract static class IteratorBasedAbstractMap<K, V> extends AbstractMap<K, V> {
+  abstract static class IteratorBasedAbstractMap<
+          K extends @Nullable Object, V extends @Nullable Object>
+      extends AbstractMap<K, V> {
     @Override
     public abstract int size();
 
@@ -3395,7 +3661,8 @@ public void clear() {
    * Delegates to {@link Map#get}. Returns {@code null} on {@code ClassCastException} and {@code
    * NullPointerException}.
    */
-  static <V> V safeGet(Map<?, V> map, @NullableDecl Object key) {
+  @CheckForNull
+  static <V extends @Nullable Object> V safeGet(Map<?, V> map, @CheckForNull Object key) {
     checkNotNull(map);
     try {
       return map.get(key);
@@ -3408,7 +3675,7 @@ static <V> V safeGet(Map<?, V> map, @NullableDecl Object key) {
    * Delegates to {@link Map#containsKey}. Returns {@code false} on {@code ClassCastException} and
    * {@code NullPointerException}.
    */
-  static boolean safeContainsKey(Map<?, ?> map, Object key) {
+  static boolean safeContainsKey(Map<?, ?> map, @CheckForNull Object key) {
     checkNotNull(map);
     try {
       return map.containsKey(key);
@@ -3421,7 +3688,8 @@ static boolean safeContainsKey(Map<?, ?> map, Object key) {
    * Delegates to {@link Map#remove}. Returns {@code null} on {@code ClassCastException} and {@code
    * NullPointerException}.
    */
-  static <V> V safeRemove(Map<?, V> map, Object key) {
+  @CheckForNull
+  static <V extends @Nullable Object> V safeRemove(Map<?, V> map, @CheckForNull Object key) {
     checkNotNull(map);
     try {
       return map.remove(key);
@@ -3431,12 +3699,12 @@ static <V> V safeRemove(Map<?, V> map, Object key) {
   }
 
   /** An admittedly inefficient implementation of {@link Map#containsKey}. */
-  static boolean containsKeyImpl(Map<?, ?> map, @NullableDecl Object key) {
+  static boolean containsKeyImpl(Map<?, ?> map, @CheckForNull Object key) {
     return Iterators.contains(keyIterator(map.entrySet().iterator()), key);
   }
 
   /** An implementation of {@link Map#containsValue}. */
-  static boolean containsValueImpl(Map<?, ?> map, @NullableDecl Object value) {
+  static boolean containsValueImpl(Map<?, ?> map, @CheckForNull Object value) {
     return Iterators.contains(valueIterator(map.entrySet().iterator()), value);
   }
 
@@ -3452,7 +3720,8 @@ static boolean containsValueImpl(Map<?, ?> map, @NullableDecl Object value) {
    * @param o the object that might be contained in {@code c}
    * @return {@code true} if {@code c} contains {@code o}
    */
-  static <K, V> boolean containsEntryImpl(Collection<Entry<K, V>> c, Object o) {
+  static <K extends @Nullable Object, V extends @Nullable Object> boolean containsEntryImpl(
+      Collection<Entry<K, V>> c, @CheckForNull Object o) {
     if (!(o instanceof Entry)) {
       return false;
     }
@@ -3470,7 +3739,8 @@ static <K, V> boolean containsEntryImpl(Collection<Entry<K, V>> c, Object o) {
    * @param o the object to remove from {@code c}
    * @return {@code true} if {@code c} was changed
    */
-  static <K, V> boolean removeEntryImpl(Collection<Entry<K, V>> c, Object o) {
+  static <K extends @Nullable Object, V extends @Nullable Object> boolean removeEntryImpl(
+      Collection<Entry<K, V>> c, @CheckForNull Object o) {
     if (!(o instanceof Entry)) {
       return false;
     }
@@ -3478,7 +3748,7 @@ static <K, V> boolean removeEntryImpl(Collection<Entry<K, V>> c, Object o) {
   }
 
   /** An implementation of {@link Map#equals}. */
-  static boolean equalsImpl(Map<?, ?> map, Object object) {
+  static boolean equalsImpl(Map<?, ?> map, @CheckForNull Object object) {
     if (map == object) {
       return true;
     } else if (object instanceof Map) {
@@ -3503,13 +3773,15 @@ static String toStringImpl(Map<?, ?> map) {
   }
 
   /** An implementation of {@link Map#putAll}. */
-  static <K, V> void putAllImpl(Map<K, V> self, Map<? extends K, ? extends V> map) {
+  static <K extends @Nullable Object, V extends @Nullable Object> void putAllImpl(
+      Map<K, V> self, Map<? extends K, ? extends V> map) {
     for (Entry<? extends K, ? extends V> entry : map.entrySet()) {
       self.put(entry.getKey(), entry.getValue());
     }
   }
 
-  static class KeySet<K, V> extends Sets.ImprovedAbstractSet<K> {
+  static class KeySet<K extends @Nullable Object, V extends @Nullable Object>
+      extends Sets.ImprovedAbstractSet<K> {
     @Weak final Map<K, V> map;
 
     KeySet(Map<K, V> map) {
@@ -3536,12 +3808,12 @@ public boolean isEmpty() {
     }
 
     @Override
-    public boolean contains(Object o) {
+    public boolean contains(@CheckForNull Object o) {
       return map().containsKey(o);
     }
 
     @Override
-    public boolean remove(Object o) {
+    public boolean remove(@CheckForNull Object o) {
       if (contains(o)) {
         map().remove(o);
         return true;
@@ -3555,17 +3827,18 @@ public void clear() {
     }
   }
 
-  @NullableDecl
-  static <K> K keyOrNull(@NullableDecl Entry<K, ?> entry) {
+  @CheckForNull
+  static <K extends @Nullable Object> K keyOrNull(@CheckForNull Entry<K, ?> entry) {
     return (entry == null) ? null : entry.getKey();
   }
 
-  @NullableDecl
-  static <V> V valueOrNull(@NullableDecl Entry<?, V> entry) {
+  @CheckForNull
+  static <V extends @Nullable Object> V valueOrNull(@CheckForNull Entry<?, V> entry) {
     return (entry == null) ? null : entry.getValue();
   }
 
-  static class SortedKeySet<K, V> extends KeySet<K, V> implements SortedSet<K> {
+  static class SortedKeySet<K extends @Nullable Object, V extends @Nullable Object>
+      extends KeySet<K, V> implements SortedSet<K> {
     SortedKeySet(SortedMap<K, V> map) {
       super(map);
     }
@@ -3576,38 +3849,42 @@ SortedMap<K, V> map() {
     }
 
     @Override
+    @CheckForNull
     public Comparator<? super K> comparator() {
       return map().comparator();
     }
 
     @Override
-    public SortedSet<K> subSet(K fromElement, K toElement) {
+    public SortedSet<K> subSet(@ParametricNullness K fromElement, @ParametricNullness K toElement) {
       return new SortedKeySet<>(map().subMap(fromElement, toElement));
     }
 
     @Override
-    public SortedSet<K> headSet(K toElement) {
+    public SortedSet<K> headSet(@ParametricNullness K toElement) {
       return new SortedKeySet<>(map().headMap(toElement));
     }
 
     @Override
-    public SortedSet<K> tailSet(K fromElement) {
+    public SortedSet<K> tailSet(@ParametricNullness K fromElement) {
       return new SortedKeySet<>(map().tailMap(fromElement));
     }
 
     @Override
+    @ParametricNullness
     public K first() {
       return map().firstKey();
     }
 
     @Override
+    @ParametricNullness
     public K last() {
       return map().lastKey();
     }
   }
 
   @GwtIncompatible // NavigableMap
-  static class NavigableKeySet<K, V> extends SortedKeySet<K, V> implements NavigableSet<K> {
+  static class NavigableKeySet<K extends @Nullable Object, V extends @Nullable Object>
+      extends SortedKeySet<K, V> implements NavigableSet<K> {
     NavigableKeySet(NavigableMap<K, V> map) {
       super(map);
     }
@@ -3618,31 +3895,37 @@ NavigableMap<K, V> map() {
     }
 
     @Override
-    public K lower(K e) {
+    @CheckForNull
+    public K lower(@ParametricNullness K e) {
       return map().lowerKey(e);
     }
 
     @Override
-    public K floor(K e) {
+    @CheckForNull
+    public K floor(@ParametricNullness K e) {
       return map().floorKey(e);
     }
 
     @Override
-    public K ceiling(K e) {
+    @CheckForNull
+    public K ceiling(@ParametricNullness K e) {
       return map().ceilingKey(e);
     }
 
     @Override
-    public K higher(K e) {
+    @CheckForNull
+    public K higher(@ParametricNullness K e) {
       return map().higherKey(e);
     }
 
     @Override
+    @CheckForNull
     public K pollFirst() {
       return keyOrNull(map().pollFirstEntry());
     }
 
     @Override
+    @CheckForNull
     public K pollLast() {
       return keyOrNull(map().pollLastEntry());
     }
@@ -3659,37 +3942,41 @@ public Iterator<K> descendingIterator() {
 
     @Override
     public NavigableSet<K> subSet(
-        K fromElement, boolean fromInclusive, K toElement, boolean toInclusive) {
+        @ParametricNullness K fromElement,
+        boolean fromInclusive,
+        @ParametricNullness K toElement,
+        boolean toInclusive) {
       return map().subMap(fromElement, fromInclusive, toElement, toInclusive).navigableKeySet();
     }
 
     @Override
-    public SortedSet<K> subSet(K fromElement, K toElement) {
+    public SortedSet<K> subSet(@ParametricNullness K fromElement, @ParametricNullness K toElement) {
       return subSet(fromElement, true, toElement, false);
     }
 
     @Override
-    public NavigableSet<K> headSet(K toElement, boolean inclusive) {
+    public NavigableSet<K> headSet(@ParametricNullness K toElement, boolean inclusive) {
       return map().headMap(toElement, inclusive).navigableKeySet();
     }
 
     @Override
-    public SortedSet<K> headSet(K toElement) {
+    public SortedSet<K> headSet(@ParametricNullness K toElement) {
       return headSet(toElement, false);
     }
 
     @Override
-    public NavigableSet<K> tailSet(K fromElement, boolean inclusive) {
+    public NavigableSet<K> tailSet(@ParametricNullness K fromElement, boolean inclusive) {
       return map().tailMap(fromElement, inclusive).navigableKeySet();
     }
 
     @Override
-    public SortedSet<K> tailSet(K fromElement) {
+    public SortedSet<K> tailSet(@ParametricNullness K fromElement) {
       return tailSet(fromElement, true);
     }
   }
 
-  static class Values<K, V> extends AbstractCollection<V> {
+  static class Values<K extends @Nullable Object, V extends @Nullable Object>
+      extends AbstractCollection<V> {
     @Weak final Map<K, V> map;
 
     Values(Map<K, V> map) {
@@ -3706,7 +3993,7 @@ public Iterator<V> iterator() {
     }
 
     @Override
-    public boolean remove(Object o) {
+    public boolean remove(@CheckForNull Object o) {
       try {
         return super.remove(o);
       } catch (UnsupportedOperationException e) {
@@ -3761,7 +4048,7 @@ public boolean isEmpty() {
     }
 
     @Override
-    public boolean contains(@NullableDecl Object o) {
+    public boolean contains(@CheckForNull Object o) {
       return map().containsValue(o);
     }
 
@@ -3771,7 +4058,8 @@ public void clear() {
     }
   }
 
-  abstract static class EntrySet<K, V> extends Sets.ImprovedAbstractSet<Entry<K, V>> {
+  abstract static class EntrySet<K extends @Nullable Object, V extends @Nullable Object>
+      extends Sets.ImprovedAbstractSet<Entry<K, V>> {
     abstract Map<K, V> map();
 
     @Override
@@ -3785,7 +4073,7 @@ public void clear() {
     }
 
     @Override
-    public boolean contains(Object o) {
+    public boolean contains(@CheckForNull Object o) {
       if (o instanceof Entry) {
         Entry<?, ?> entry = (Entry<?, ?>) o;
         Object key = entry.getKey();
@@ -3801,8 +4089,12 @@ public boolean isEmpty() {
     }
 
     @Override
-    public boolean remove(Object o) {
-      if (contains(o)) {
+    public boolean remove(@CheckForNull Object o) {
+      /*
+       * `o instanceof Entry` is guaranteed by `contains`, but we check it here to satisfy our
+       * nullness checker.
+       */
+      if (contains(o) && o instanceof Entry) {
         Entry<?, ?> entry = (Entry<?, ?>) o;
         return map().keySet().remove(entry.getKey());
       }
@@ -3825,9 +4117,13 @@ public boolean retainAll(Collection<?> c) {
         return super.retainAll(checkNotNull(c));
       } catch (UnsupportedOperationException e) {
         // if the iterators don't support remove
-        Set<Object> keys = Sets.newHashSetWithExpectedSize(c.size());
+        Set<@Nullable Object> keys = Sets.newHashSetWithExpectedSize(c.size());
         for (Object o : c) {
-          if (contains(o)) {
+          /*
+           * `o instanceof Entry` is guaranteed by `contains`, but we check it here to satisfy our
+           * nullness checker.
+           */
+          if (contains(o) && o instanceof Entry) {
             Entry<?, ?> entry = (Entry<?, ?>) o;
             keys.add(entry.getKey());
           }
@@ -3838,8 +4134,8 @@ public boolean retainAll(Collection<?> c) {
   }
 
   @GwtIncompatible // NavigableMap
-  abstract static class DescendingMap<K, V> extends ForwardingMap<K, V>
-      implements NavigableMap<K, V> {
+  abstract static class DescendingMap<K extends @Nullable Object, V extends @Nullable Object>
+      extends ForwardingMap<K, V> implements NavigableMap<K, V> {
 
     abstract NavigableMap<K, V> forward();
 
@@ -3848,7 +4144,7 @@ protected final Map<K, V> delegate() {
       return forward();
     }
 
-    @NullableDecl private transient Comparator<? super K> comparator;
+    @CheckForNull private transient Comparator<? super K> comparator;
 
     @SuppressWarnings("unchecked")
     @Override
@@ -3865,76 +4161,90 @@ public Comparator<? super K> comparator() {
     }
 
     // If we inline this, we get a javac error.
-    private static <T> Ordering<T> reverse(Comparator<T> forward) {
+    private static <T extends @Nullable Object> Ordering<T> reverse(Comparator<T> forward) {
       return Ordering.from(forward).reverse();
     }
 
     @Override
+    @ParametricNullness
     public K firstKey() {
       return forward().lastKey();
     }
 
     @Override
+    @ParametricNullness
     public K lastKey() {
       return forward().firstKey();
     }
 
     @Override
-    public Entry<K, V> lowerEntry(K key) {
+    @CheckForNull
+    public Entry<K, V> lowerEntry(@ParametricNullness K key) {
       return forward().higherEntry(key);
     }
 
     @Override
-    public K lowerKey(K key) {
+    @CheckForNull
+    public K lowerKey(@ParametricNullness K key) {
       return forward().higherKey(key);
     }
 
     @Override
-    public Entry<K, V> floorEntry(K key) {
+    @CheckForNull
+    public Entry<K, V> floorEntry(@ParametricNullness K key) {
       return forward().ceilingEntry(key);
     }
 
     @Override
-    public K floorKey(K key) {
+    @CheckForNull
+    public K floorKey(@ParametricNullness K key) {
       return forward().ceilingKey(key);
     }
 
     @Override
-    public Entry<K, V> ceilingEntry(K key) {
+    @CheckForNull
+    public Entry<K, V> ceilingEntry(@ParametricNullness K key) {
       return forward().floorEntry(key);
     }
 
     @Override
-    public K ceilingKey(K key) {
+    @CheckForNull
+    public K ceilingKey(@ParametricNullness K key) {
       return forward().floorKey(key);
     }
 
     @Override
-    public Entry<K, V> higherEntry(K key) {
+    @CheckForNull
+    public Entry<K, V> higherEntry(@ParametricNullness K key) {
       return forward().lowerEntry(key);
     }
 
     @Override
-    public K higherKey(K key) {
+    @CheckForNull
+    public K higherKey(@ParametricNullness K key) {
       return forward().lowerKey(key);
     }
 
     @Override
+    @CheckForNull
     public Entry<K, V> firstEntry() {
       return forward().lastEntry();
     }
 
     @Override
+    @CheckForNull
     public Entry<K, V> lastEntry() {
       return forward().firstEntry();
     }
 
     @Override
+    @CheckForNull
     public Entry<K, V> pollFirstEntry() {
       return forward().pollLastEntry();
     }
 
     @Override
+    @CheckForNull
     public Entry<K, V> pollLastEntry() {
       return forward().pollFirstEntry();
     }
@@ -3944,7 +4254,7 @@ public NavigableMap<K, V> descendingMap() {
       return forward();
     }
 
-    @NullableDecl private transient Set<Entry<K, V>> entrySet;
+    @CheckForNull private transient Set<Entry<K, V>> entrySet;
 
     @Override
     public Set<Entry<K, V>> entrySet() {
@@ -3975,7 +4285,7 @@ public Set<K> keySet() {
       return navigableKeySet();
     }
 
-    @NullableDecl private transient NavigableSet<K> navigableKeySet;
+    @CheckForNull private transient NavigableSet<K> navigableKeySet;
 
     @Override
     public NavigableSet<K> navigableKeySet() {
@@ -3990,32 +4300,35 @@ public NavigableSet<K> descendingKeySet() {
 
     @Override
     public NavigableMap<K, V> subMap(
-        K fromKey, boolean fromInclusive, K toKey, boolean toInclusive) {
+        @ParametricNullness K fromKey,
+        boolean fromInclusive,
+        @ParametricNullness K toKey,
+        boolean toInclusive) {
       return forward().subMap(toKey, toInclusive, fromKey, fromInclusive).descendingMap();
     }
 
     @Override
-    public SortedMap<K, V> subMap(K fromKey, K toKey) {
+    public SortedMap<K, V> subMap(@ParametricNullness K fromKey, @ParametricNullness K toKey) {
       return subMap(fromKey, true, toKey, false);
     }
 
     @Override
-    public NavigableMap<K, V> headMap(K toKey, boolean inclusive) {
+    public NavigableMap<K, V> headMap(@ParametricNullness K toKey, boolean inclusive) {
       return forward().tailMap(toKey, inclusive).descendingMap();
     }
 
     @Override
-    public SortedMap<K, V> headMap(K toKey) {
+    public SortedMap<K, V> headMap(@ParametricNullness K toKey) {
       return headMap(toKey, false);
     }
 
     @Override
-    public NavigableMap<K, V> tailMap(K fromKey, boolean inclusive) {
+    public NavigableMap<K, V> tailMap(@ParametricNullness K fromKey, boolean inclusive) {
       return forward().headMap(fromKey, inclusive).descendingMap();
     }
 
     @Override
-    public SortedMap<K, V> tailMap(K fromKey) {
+    public SortedMap<K, V> tailMap(@ParametricNullness K fromKey) {
       return tailMap(fromKey, true);
     }
 
@@ -4037,7 +4350,7 @@ static <E> ImmutableMap<E, Integer> indexMap(Collection<E> list) {
     for (E e : list) {
       builder.put(e, i++);
     }
-    return builder.build();
+    return builder.buildOrThrow();
   }
 
   /**
@@ -4058,8 +4371,8 @@ static <E> ImmutableMap<E, Integer> indexMap(Collection<E> list) {
    */
   @Beta
   @GwtIncompatible // NavigableMap
-  public static <K extends Comparable<? super K>, V> NavigableMap<K, V> subMap(
-      NavigableMap<K, V> map, Range<K> range) {
+  public static <K extends Comparable<? super K>, V extends @Nullable Object>
+      NavigableMap<K, V> subMap(NavigableMap<K, V> map, Range<K> range) {
     if (map.comparator() != null
         && map.comparator() != Ordering.natural()
         && range.hasLowerBound()
diff --git a/android/guava/src/com/google/common/collect/MinMaxPriorityQueue.java b/android/guava/src/com/google/common/collect/MinMaxPriorityQueue.java
index 639775c5bedf..181b3fbb50b3 100644
--- a/android/guava/src/com/google/common/collect/MinMaxPriorityQueue.java
+++ b/android/guava/src/com/google/common/collect/MinMaxPriorityQueue.java
@@ -21,6 +21,7 @@
 import static com.google.common.base.Preconditions.checkPositionIndex;
 import static com.google.common.base.Preconditions.checkState;
 import static com.google.common.collect.CollectPreconditions.checkRemove;
+import static java.util.Objects.requireNonNull;
 
 import com.google.common.annotations.Beta;
 import com.google.common.annotations.GwtCompatible;
@@ -41,7 +42,8 @@
 import java.util.NoSuchElementException;
 import java.util.PriorityQueue;
 import java.util.Queue;
-import org.checkerframework.checker.nullness.compatqual.NullableDecl;
+import javax.annotation.CheckForNull;
+import org.checkerframework.checker.nullness.qual.Nullable;
 
 /**
  * A double-ended priority queue, which provides constant-time access to both its least element and
@@ -98,6 +100,7 @@
  */
 @Beta
 @GwtCompatible
+@ElementTypesAreNonnullByDefault
 public final class MinMaxPriorityQueue<E> extends AbstractQueue<E> {
 
   /**
@@ -121,8 +124,14 @@ public static <E extends Comparable<E>> MinMaxPriorityQueue<E> create(
    * Creates and returns a new builder, configured to build {@code MinMaxPriorityQueue} instances
    * that use {@code comparator} to determine the least and greatest elements.
    */
+  /*
+   * TODO(cpovirk): Change to Comparator<? super B> to permit Comparator<@Nullable ...> and
+   * Comparator<SupertypeOfB>? What we have here matches the immutable collections, but those also
+   * expose a public Builder constructor that accepts "? super." So maybe we should do *that*
+   * instead.
+   */
   public static <B> Builder<B> orderedBy(Comparator<B> comparator) {
-    return new Builder<B>(comparator);
+    return new Builder<>(comparator);
   }
 
   /**
@@ -207,7 +216,7 @@ public <T extends B> MinMaxPriorityQueue<T> create() {
      */
     public <T extends B> MinMaxPriorityQueue<T> create(Iterable<? extends T> initialContents) {
       MinMaxPriorityQueue<T> queue =
-          new MinMaxPriorityQueue<T>(
+          new MinMaxPriorityQueue<>(
               this, initialQueueSize(expectedSize, maximumSize, initialContents));
       for (T element : initialContents) {
         queue.offer(element);
@@ -224,7 +233,7 @@ private <T extends B> Ordering<T> ordering() {
   private final Heap minHeap;
   private final Heap maxHeap;
   @VisibleForTesting final int maximumSize;
-  private Object[] queue;
+  private @Nullable Object[] queue;
   private int size;
   private int modCount;
 
@@ -292,16 +301,22 @@ public boolean offer(E element) {
 
   @CanIgnoreReturnValue
   @Override
+  @CheckForNull
   public E poll() {
     return isEmpty() ? null : removeAndGet(0);
   }
 
   @SuppressWarnings("unchecked") // we must carefully only allow Es to get in
   E elementData(int index) {
-    return (E) queue[index];
+    /*
+     * requireNonNull is safe as long as we're careful to call this method only with populated
+     * indexes.
+     */
+    return (E) requireNonNull(queue[index]);
   }
 
   @Override
+  @CheckForNull
   public E peek() {
     return isEmpty() ? null : elementData(0);
   }
@@ -325,6 +340,7 @@ private int getMaxElementIndex() {
    * empty.
    */
   @CanIgnoreReturnValue
+  @CheckForNull
   public E pollFirst() {
     return poll();
   }
@@ -343,6 +359,7 @@ public E removeFirst() {
    * Retrieves, but does not remove, the least element of this queue, or returns {@code null} if the
    * queue is empty.
    */
+  @CheckForNull
   public E peekFirst() {
     return peek();
   }
@@ -352,6 +369,7 @@ public E peekFirst() {
    * empty.
    */
   @CanIgnoreReturnValue
+  @CheckForNull
   public E pollLast() {
     return isEmpty() ? null : removeAndGet(getMaxElementIndex());
   }
@@ -373,6 +391,7 @@ public E removeLast() {
    * Retrieves, but does not remove, the greatest element of this queue, or returns {@code null} if
    * the queue is empty.
    */
+  @CheckForNull
   public E peekLast() {
     return isEmpty() ? null : elementData(getMaxElementIndex());
   }
@@ -392,6 +411,7 @@ public E peekLast() {
    */
   @VisibleForTesting
   @CanIgnoreReturnValue
+  @CheckForNull
   MoveDesc<E> removeAt(int index) {
     checkPositionIndex(index, size);
     modCount++;
@@ -416,17 +436,18 @@ MoveDesc<E> removeAt(int index) {
       // Last element is moved to before index, swapped with trickled element.
       if (changes == null) {
         // The trickled element is still after index.
-        return new MoveDesc<E>(actualLastElement, toTrickle);
+        return new MoveDesc<>(actualLastElement, toTrickle);
       } else {
         // The trickled element is back before index, but the replaced element
         // has now been moved after index.
-        return new MoveDesc<E>(actualLastElement, changes.replaced);
+        return new MoveDesc<>(actualLastElement, changes.replaced);
       }
     }
     // Trickled element was after index to begin with, no adjustment needed.
     return changes;
   }
 
+  @CheckForNull
   private MoveDesc<E> fillHole(int index, E toTrickle) {
     Heap heap = heapForIndex(index);
     // We consider elementData(index) a "hole", and we want to fill it
@@ -504,7 +525,7 @@ boolean isIntact() {
   @WeakOuter
   private class Heap {
     final Ordering<E> ordering;
-    @Weak @NullableDecl Heap otherHeap;
+    @Weak Heap otherHeap; // always initialized immediately after construction
 
     Heap(Ordering<E> ordering) {
       this.ordering = ordering;
@@ -518,6 +539,7 @@ int compareElements(int a, int b) {
      * Tries to move {@code toTrickle} from a min to a max level and bubble up there. If it moved
      * before {@code removeIndex} this method returns a pair as described in {@link #removeAt}.
      */
+    @CheckForNull
     MoveDesc<E> tryCrossOverAndBubbleUp(int removeIndex, int vacated, E toTrickle) {
       int crossOver = crossOver(vacated, toTrickle);
       if (crossOver == vacated) {
@@ -538,7 +560,7 @@ MoveDesc<E> tryCrossOverAndBubbleUp(int removeIndex, int vacated, E toTrickle) {
       }
       // bubble it up the opposite heap
       if (otherHeap.bubbleUpAlternatingLevels(crossOver, toTrickle) < removeIndex) {
-        return new MoveDesc<E>(toTrickle, parent);
+        return new MoveDesc<>(toTrickle, parent);
       } else {
         return null;
       }
@@ -751,9 +773,9 @@ private class QueueIterator implements Iterator<E> {
     private int expectedModCount = modCount;
     // The same element is not allowed in both forgetMeNot and skipMe, but duplicates are allowed in
     // either of them, up to the same multiplicity as the queue.
-    @NullableDecl private Queue<E> forgetMeNot;
-    @NullableDecl private List<E> skipMe;
-    @NullableDecl private E lastFromForgetMeNot;
+    @CheckForNull private Queue<E> forgetMeNot;
+    @CheckForNull private List<E> skipMe;
+    @CheckForNull private E lastFromForgetMeNot;
     private boolean canRemove;
 
     @Override
@@ -791,9 +813,10 @@ public void remove() {
       if (cursor < size()) {
         MoveDesc<E> moved = removeAt(cursor);
         if (moved != null) {
-          if (forgetMeNot == null) {
-            forgetMeNot = new ArrayDeque<E>();
-            skipMe = new ArrayList<E>(3);
+          // Either both are null or neither is, but we check both to satisfy the nullness checker.
+          if (forgetMeNot == null || skipMe == null) {
+            forgetMeNot = new ArrayDeque<>();
+            skipMe = new ArrayList<>(3);
           }
           if (!foundAndRemovedExactReference(skipMe, moved.toTrickle)) {
             forgetMeNot.add(moved.toTrickle);
@@ -805,7 +828,7 @@ public void remove() {
         cursor--;
         nextCursor--;
       } else { // we must have set lastFromForgetMeNot in next()
-        checkState(removeExact(lastFromForgetMeNot));
+        checkState(removeExact(requireNonNull(lastFromForgetMeNot)));
         lastFromForgetMeNot = null;
       }
     }
diff --git a/android/guava/src/com/google/common/collect/Multimap.java b/android/guava/src/com/google/common/collect/Multimap.java
index cdfa0f6906dd..41aed97f1b8a 100644
--- a/android/guava/src/com/google/common/collect/Multimap.java
+++ b/android/guava/src/com/google/common/collect/Multimap.java
@@ -25,7 +25,8 @@
 import java.util.Map;
 import java.util.Map.Entry;
 import java.util.Set;
-import org.checkerframework.checker.nullness.compatqual.NullableDecl;
+import javax.annotation.CheckForNull;
+import org.checkerframework.checker.nullness.qual.Nullable;
 
 /**
  * A collection that maps keys to values, similar to {@link Map}, but in which each key may be
@@ -150,15 +151,15 @@
  * {@link UnsupportedOperationException}.
  *
  * <p>See the Guava User Guide article on <a href=
- * "https://github.com/google/guava/wiki/NewCollectionTypesExplained#multimap"> {@code
- * Multimap}</a>.
+ * "https://github.com/google/guava/wiki/NewCollectionTypesExplained#multimap">{@code Multimap}</a>.
  *
  * @author Jared Levy
  * @since 2.0
  */
 @DoNotMock("Use ImmutableMultimap, HashMultimap, or another implementation")
 @GwtCompatible
-public interface Multimap<K, V> {
+@ElementTypesAreNonnullByDefault
+public interface Multimap<K extends @Nullable Object, V extends @Nullable Object> {
   // Query Operations
 
   /**
@@ -180,21 +181,21 @@ public interface Multimap<K, V> {
    * Returns {@code true} if this multimap contains at least one key-value pair with the key {@code
    * key}.
    */
-  boolean containsKey(@CompatibleWith("K") @NullableDecl Object key);
+  boolean containsKey(@CompatibleWith("K") @CheckForNull Object key);
 
   /**
    * Returns {@code true} if this multimap contains at least one key-value pair with the value
    * {@code value}.
    */
-  boolean containsValue(@CompatibleWith("V") @NullableDecl Object value);
+  boolean containsValue(@CompatibleWith("V") @CheckForNull Object value);
 
   /**
    * Returns {@code true} if this multimap contains at least one key-value pair with the key {@code
    * key} and the value {@code value}.
    */
   boolean containsEntry(
-      @CompatibleWith("K") @NullableDecl Object key,
-      @CompatibleWith("V") @NullableDecl Object value);
+      @CompatibleWith("K") @CheckForNull Object key,
+      @CompatibleWith("V") @CheckForNull Object value);
 
   // Modification Operations
 
@@ -209,7 +210,7 @@ boolean containsEntry(
    *     multimap already contained the key-value pair and doesn't allow duplicates
    */
   @CanIgnoreReturnValue
-  boolean put(@NullableDecl K key, @NullableDecl V value);
+  boolean put(@ParametricNullness K key, @ParametricNullness V value);
 
   /**
    * Removes a single key-value pair with the key {@code key} and the value {@code value} from this
@@ -220,8 +221,8 @@ boolean containsEntry(
    */
   @CanIgnoreReturnValue
   boolean remove(
-      @CompatibleWith("K") @NullableDecl Object key,
-      @CompatibleWith("V") @NullableDecl Object value);
+      @CompatibleWith("K") @CheckForNull Object key,
+      @CompatibleWith("V") @CheckForNull Object value);
 
   // Bulk Operations
 
@@ -240,7 +241,7 @@ boolean remove(
    * @return {@code true} if the multimap changed
    */
   @CanIgnoreReturnValue
-  boolean putAll(@NullableDecl K key, Iterable<? extends V> values);
+  boolean putAll(@ParametricNullness K key, Iterable<? extends V> values);
 
   /**
    * Stores all key-value pairs of {@code multimap} in this multimap, in the order returned by
@@ -261,7 +262,7 @@ boolean remove(
    *     no effect on the multimap.
    */
   @CanIgnoreReturnValue
-  Collection<V> replaceValues(@NullableDecl K key, Iterable<? extends V> values);
+  Collection<V> replaceValues(@ParametricNullness K key, Iterable<? extends V> values);
 
   /**
    * Removes all values associated with the key {@code key}.
@@ -273,7 +274,7 @@ boolean remove(
    *     modifiable, but updating it will have no effect on the multimap.
    */
   @CanIgnoreReturnValue
-  Collection<V> removeAll(@CompatibleWith("K") @NullableDecl Object key);
+  Collection<V> removeAll(@CompatibleWith("K") @CheckForNull Object key);
 
   /** Removes all key-value pairs from the multimap, leaving it {@linkplain #isEmpty empty}. */
   void clear();
@@ -287,7 +288,7 @@ boolean remove(
    *
    * <p>Changes to the returned collection will update the underlying multimap, and vice versa.
    */
-  Collection<V> get(@NullableDecl K key);
+  Collection<V> get(@ParametricNullness K key);
 
   /**
    * Returns a view collection of all <i>distinct</i> keys contained in this multimap. Note that the
@@ -354,7 +355,7 @@ boolean remove(
    * multimaps are equal, because they both have empty {@link #asMap} views.
    */
   @Override
-  boolean equals(@NullableDecl Object obj);
+  boolean equals(@CheckForNull Object obj);
 
   /**
    * Returns the hash code for this multimap.
diff --git a/android/guava/src/com/google/common/collect/MultimapBuilder.java b/android/guava/src/com/google/common/collect/MultimapBuilder.java
index 161c29d170ee..3d6278aaec9d 100644
--- a/android/guava/src/com/google/common/collect/MultimapBuilder.java
+++ b/android/guava/src/com/google/common/collect/MultimapBuilder.java
@@ -34,6 +34,7 @@
 import java.util.SortedSet;
 import java.util.TreeMap;
 import java.util.TreeSet;
+import org.checkerframework.checker.nullness.qual.Nullable;
 
 /**
  * A builder for a multimap implementation that allows customization of the backing map and value
@@ -61,7 +62,8 @@
  * @since 16.0
  */
 @GwtCompatible
-public abstract class MultimapBuilder<K0, V0> {
+@ElementTypesAreNonnullByDefault
+public abstract class MultimapBuilder<K0 extends @Nullable Object, V0 extends @Nullable Object> {
   /*
    * Leaving K and V as upper bounds rather than the actual key and value types allows type
    * parameters to be left implicit more often. CacheBuilder uses the same technique.
@@ -72,7 +74,7 @@ private MultimapBuilder() {}
   private static final int DEFAULT_EXPECTED_KEYS = 8;
 
   /** Uses a hash table to map keys to value collections. */
-  public static MultimapBuilderWithKeys<Object> hashKeys() {
+  public static MultimapBuilderWithKeys<@Nullable Object> hashKeys() {
     return hashKeys(DEFAULT_EXPECTED_KEYS);
   }
 
@@ -82,11 +84,11 @@ public static MultimapBuilderWithKeys<Object> hashKeys() {
    *
    * @throws IllegalArgumentException if {@code expectedKeys < 0}
    */
-  public static MultimapBuilderWithKeys<Object> hashKeys(final int expectedKeys) {
+  public static MultimapBuilderWithKeys<@Nullable Object> hashKeys(int expectedKeys) {
     checkNonnegative(expectedKeys, "expectedKeys");
-    return new MultimapBuilderWithKeys<Object>() {
+    return new MultimapBuilderWithKeys<@Nullable Object>() {
       @Override
-      <K, V> Map<K, Collection<V>> createMap() {
+      <K extends @Nullable Object, V extends @Nullable Object> Map<K, Collection<V>> createMap() {
         return Platform.newHashMapWithExpectedSize(expectedKeys);
       }
     };
@@ -100,7 +102,7 @@ <K, V> Map<K, Collection<V>> createMap() {
    * multimap, save that if all values associated with a key are removed and then the key is added
    * back into the multimap, that key will come last in the key iteration order.
    */
-  public static MultimapBuilderWithKeys<Object> linkedHashKeys() {
+  public static MultimapBuilderWithKeys<@Nullable Object> linkedHashKeys() {
     return linkedHashKeys(DEFAULT_EXPECTED_KEYS);
   }
 
@@ -113,11 +115,11 @@ public static MultimapBuilderWithKeys<Object> linkedHashKeys() {
    * multimap, save that if all values associated with a key are removed and then the key is added
    * back into the multimap, that key will come last in the key iteration order.
    */
-  public static MultimapBuilderWithKeys<Object> linkedHashKeys(final int expectedKeys) {
+  public static MultimapBuilderWithKeys<@Nullable Object> linkedHashKeys(int expectedKeys) {
     checkNonnegative(expectedKeys, "expectedKeys");
-    return new MultimapBuilderWithKeys<Object>() {
+    return new MultimapBuilderWithKeys<@Nullable Object>() {
       @Override
-      <K, V> Map<K, Collection<V>> createMap() {
+      <K extends @Nullable Object, V extends @Nullable Object> Map<K, Collection<V>> createMap() {
         return Platform.newLinkedHashMapWithExpectedSize(expectedKeys);
       }
     };
@@ -151,11 +153,12 @@ public static MultimapBuilderWithKeys<Comparable> treeKeys() {
    * <p>Multimaps generated by the resulting builder will not be serializable if {@code comparator}
    * is not serializable.
    */
-  public static <K0> MultimapBuilderWithKeys<K0> treeKeys(final Comparator<K0> comparator) {
+  public static <K0 extends @Nullable Object> MultimapBuilderWithKeys<K0> treeKeys(
+      Comparator<K0> comparator) {
     checkNotNull(comparator);
     return new MultimapBuilderWithKeys<K0>() {
       @Override
-      <K extends K0, V> Map<K, Collection<V>> createMap() {
+      <K extends K0, V extends @Nullable Object> Map<K, Collection<V>> createMap() {
         return new TreeMap<>(comparator);
       }
     };
@@ -166,13 +169,12 @@ <K extends K0, V> Map<K, Collection<V>> createMap() {
    *
    * @since 16.0
    */
-  public static <K0 extends Enum<K0>> MultimapBuilderWithKeys<K0> enumKeys(
-      final Class<K0> keyClass) {
+  public static <K0 extends Enum<K0>> MultimapBuilderWithKeys<K0> enumKeys(Class<K0> keyClass) {
     checkNotNull(keyClass);
     return new MultimapBuilderWithKeys<K0>() {
       @SuppressWarnings("unchecked")
       @Override
-      <K extends K0, V> Map<K, Collection<V>> createMap() {
+      <K extends K0, V extends @Nullable Object> Map<K, Collection<V>> createMap() {
         // K must actually be K0, since enums are effectively final
         // (their subclasses are inaccessible)
         return (Map<K, Collection<V>>) new EnumMap<K0, Collection<V>>(keyClass);
@@ -180,7 +182,8 @@ <K extends K0, V> Map<K, Collection<V>> createMap() {
     };
   }
 
-  private static final class ArrayListSupplier<V> implements Supplier<List<V>>, Serializable {
+  private static final class ArrayListSupplier<V extends @Nullable Object>
+      implements Supplier<List<V>>, Serializable {
     private final int expectedValuesPerKey;
 
     ArrayListSupplier(int expectedValuesPerKey) {
@@ -189,14 +192,14 @@ private static final class ArrayListSupplier<V> implements Supplier<List<V>>, Se
 
     @Override
     public List<V> get() {
-      return new ArrayList<V>(expectedValuesPerKey);
+      return new ArrayList<>(expectedValuesPerKey);
     }
   }
 
-  private enum LinkedListSupplier implements Supplier<List<Object>> {
+  private enum LinkedListSupplier implements Supplier<List<?>> {
     INSTANCE;
 
-    public static <V> Supplier<List<V>> instance() {
+    public static <V extends @Nullable Object> Supplier<List<V>> instance() {
       // Each call generates a fresh LinkedList, which can serve as a List<V> for any V.
       @SuppressWarnings({"rawtypes", "unchecked"})
       Supplier<List<V>> result = (Supplier) INSTANCE;
@@ -204,12 +207,13 @@ public static <V> Supplier<List<V>> instance() {
     }
 
     @Override
-    public List<Object> get() {
+    public List<?> get() {
       return new LinkedList<>();
     }
   }
 
-  private static final class HashSetSupplier<V> implements Supplier<Set<V>>, Serializable {
+  private static final class HashSetSupplier<V extends @Nullable Object>
+      implements Supplier<Set<V>>, Serializable {
     private final int expectedValuesPerKey;
 
     HashSetSupplier(int expectedValuesPerKey) {
@@ -222,7 +226,8 @@ public Set<V> get() {
     }
   }
 
-  private static final class LinkedHashSetSupplier<V> implements Supplier<Set<V>>, Serializable {
+  private static final class LinkedHashSetSupplier<V extends @Nullable Object>
+      implements Supplier<Set<V>>, Serializable {
     private final int expectedValuesPerKey;
 
     LinkedHashSetSupplier(int expectedValuesPerKey) {
@@ -235,7 +240,8 @@ public Set<V> get() {
     }
   }
 
-  private static final class TreeSetSupplier<V> implements Supplier<SortedSet<V>>, Serializable {
+  private static final class TreeSetSupplier<V extends @Nullable Object>
+      implements Supplier<SortedSet<V>>, Serializable {
     private final Comparator<? super V> comparator;
 
     TreeSetSupplier(Comparator<? super V> comparator) {
@@ -244,7 +250,7 @@ private static final class TreeSetSupplier<V> implements Supplier<SortedSet<V>>,
 
     @Override
     public SortedSet<V> get() {
-      return new TreeSet<V>(comparator);
+      return new TreeSet<>(comparator);
     }
   }
 
@@ -269,16 +275,16 @@ public Set<V> get() {
    * @param <K0> The upper bound on the key type of the generated multimap.
    * @since 16.0
    */
-  public abstract static class MultimapBuilderWithKeys<K0> {
+  public abstract static class MultimapBuilderWithKeys<K0 extends @Nullable Object> {
 
     private static final int DEFAULT_EXPECTED_VALUES_PER_KEY = 2;
 
     MultimapBuilderWithKeys() {}
 
-    abstract <K extends K0, V> Map<K, Collection<V>> createMap();
+    abstract <K extends K0, V extends @Nullable Object> Map<K, Collection<V>> createMap();
 
     /** Uses an {@link ArrayList} to store value collections. */
-    public ListMultimapBuilder<K0, Object> arrayListValues() {
+    public ListMultimapBuilder<K0, @Nullable Object> arrayListValues() {
       return arrayListValues(DEFAULT_EXPECTED_VALUES_PER_KEY);
     }
 
@@ -288,11 +294,11 @@ public ListMultimapBuilder<K0, Object> arrayListValues() {
      *
      * @throws IllegalArgumentException if {@code expectedValuesPerKey < 0}
      */
-    public ListMultimapBuilder<K0, Object> arrayListValues(final int expectedValuesPerKey) {
+    public ListMultimapBuilder<K0, @Nullable Object> arrayListValues(int expectedValuesPerKey) {
       checkNonnegative(expectedValuesPerKey, "expectedValuesPerKey");
-      return new ListMultimapBuilder<K0, Object>() {
+      return new ListMultimapBuilder<K0, @Nullable Object>() {
         @Override
-        public <K extends K0, V> ListMultimap<K, V> build() {
+        public <K extends K0, V extends @Nullable Object> ListMultimap<K, V> build() {
           return Multimaps.newListMultimap(
               MultimapBuilderWithKeys.this.<K, V>createMap(),
               new ArrayListSupplier<V>(expectedValuesPerKey));
@@ -301,10 +307,10 @@ public <K extends K0, V> ListMultimap<K, V> build() {
     }
 
     /** Uses a {@link LinkedList} to store value collections. */
-    public ListMultimapBuilder<K0, Object> linkedListValues() {
-      return new ListMultimapBuilder<K0, Object>() {
+    public ListMultimapBuilder<K0, @Nullable Object> linkedListValues() {
+      return new ListMultimapBuilder<K0, @Nullable Object>() {
         @Override
-        public <K extends K0, V> ListMultimap<K, V> build() {
+        public <K extends K0, V extends @Nullable Object> ListMultimap<K, V> build() {
           return Multimaps.newListMultimap(
               MultimapBuilderWithKeys.this.<K, V>createMap(), LinkedListSupplier.<V>instance());
         }
@@ -312,7 +318,7 @@ public <K extends K0, V> ListMultimap<K, V> build() {
     }
 
     /** Uses a hash-based {@code Set} to store value collections. */
-    public SetMultimapBuilder<K0, Object> hashSetValues() {
+    public SetMultimapBuilder<K0, @Nullable Object> hashSetValues() {
       return hashSetValues(DEFAULT_EXPECTED_VALUES_PER_KEY);
     }
 
@@ -322,11 +328,11 @@ public SetMultimapBuilder<K0, Object> hashSetValues() {
      *
      * @throws IllegalArgumentException if {@code expectedValuesPerKey < 0}
      */
-    public SetMultimapBuilder<K0, Object> hashSetValues(final int expectedValuesPerKey) {
+    public SetMultimapBuilder<K0, @Nullable Object> hashSetValues(int expectedValuesPerKey) {
       checkNonnegative(expectedValuesPerKey, "expectedValuesPerKey");
-      return new SetMultimapBuilder<K0, Object>() {
+      return new SetMultimapBuilder<K0, @Nullable Object>() {
         @Override
-        public <K extends K0, V> SetMultimap<K, V> build() {
+        public <K extends K0, V extends @Nullable Object> SetMultimap<K, V> build() {
           return Multimaps.newSetMultimap(
               MultimapBuilderWithKeys.this.<K, V>createMap(),
               new HashSetSupplier<V>(expectedValuesPerKey));
@@ -335,7 +341,7 @@ public <K extends K0, V> SetMultimap<K, V> build() {
     }
 
     /** Uses an insertion-ordered hash-based {@code Set} to store value collections. */
-    public SetMultimapBuilder<K0, Object> linkedHashSetValues() {
+    public SetMultimapBuilder<K0, @Nullable Object> linkedHashSetValues() {
       return linkedHashSetValues(DEFAULT_EXPECTED_VALUES_PER_KEY);
     }
 
@@ -345,11 +351,11 @@ public SetMultimapBuilder<K0, Object> linkedHashSetValues() {
      *
      * @throws IllegalArgumentException if {@code expectedValuesPerKey < 0}
      */
-    public SetMultimapBuilder<K0, Object> linkedHashSetValues(final int expectedValuesPerKey) {
+    public SetMultimapBuilder<K0, @Nullable Object> linkedHashSetValues(int expectedValuesPerKey) {
       checkNonnegative(expectedValuesPerKey, "expectedValuesPerKey");
-      return new SetMultimapBuilder<K0, Object>() {
+      return new SetMultimapBuilder<K0, @Nullable Object>() {
         @Override
-        public <K extends K0, V> SetMultimap<K, V> build() {
+        public <K extends K0, V extends @Nullable Object> SetMultimap<K, V> build() {
           return Multimaps.newSetMultimap(
               MultimapBuilderWithKeys.this.<K, V>createMap(),
               new LinkedHashSetSupplier<V>(expectedValuesPerKey));
@@ -369,7 +375,8 @@ public SortedSetMultimapBuilder<K0, Comparable> treeSetValues() {
      * <p>Multimaps generated by the resulting builder will not be serializable if {@code
      * comparator} is not serializable.
      */
-    public <V0> SortedSetMultimapBuilder<K0, V0> treeSetValues(final Comparator<V0> comparator) {
+    public <V0 extends @Nullable Object> SortedSetMultimapBuilder<K0, V0> treeSetValues(
+        Comparator<V0> comparator) {
       checkNotNull(comparator, "comparator");
       return new SortedSetMultimapBuilder<K0, V0>() {
         @Override
@@ -381,8 +388,7 @@ public <K extends K0, V extends V0> SortedSetMultimap<K, V> build() {
     }
 
     /** Uses an {@link EnumSet} to store value collections. */
-    public <V0 extends Enum<V0>> SetMultimapBuilder<K0, V0> enumSetValues(
-        final Class<V0> valueClass) {
+    public <V0 extends Enum<V0>> SetMultimapBuilder<K0, V0> enumSetValues(Class<V0> valueClass) {
       checkNotNull(valueClass, "valueClass");
       return new SetMultimapBuilder<K0, V0>() {
         @Override
@@ -416,7 +422,9 @@ public <K extends K0, V extends V0> Multimap<K, V> build(
    *
    * @since 16.0
    */
-  public abstract static class ListMultimapBuilder<K0, V0> extends MultimapBuilder<K0, V0> {
+  public abstract static class ListMultimapBuilder<
+          K0 extends @Nullable Object, V0 extends @Nullable Object>
+      extends MultimapBuilder<K0, V0> {
     ListMultimapBuilder() {}
 
     @Override
@@ -434,7 +442,9 @@ public <K extends K0, V extends V0> ListMultimap<K, V> build(
    *
    * @since 16.0
    */
-  public abstract static class SetMultimapBuilder<K0, V0> extends MultimapBuilder<K0, V0> {
+  public abstract static class SetMultimapBuilder<
+          K0 extends @Nullable Object, V0 extends @Nullable Object>
+      extends MultimapBuilder<K0, V0> {
     SetMultimapBuilder() {}
 
     @Override
@@ -452,7 +462,9 @@ public <K extends K0, V extends V0> SetMultimap<K, V> build(
    *
    * @since 16.0
    */
-  public abstract static class SortedSetMultimapBuilder<K0, V0> extends SetMultimapBuilder<K0, V0> {
+  public abstract static class SortedSetMultimapBuilder<
+          K0 extends @Nullable Object, V0 extends @Nullable Object>
+      extends SetMultimapBuilder<K0, V0> {
     SortedSetMultimapBuilder() {}
 
     @Override
diff --git a/android/guava/src/com/google/common/collect/Multimaps.java b/android/guava/src/com/google/common/collect/Multimaps.java
index b3b09ef73595..9976b4a66cd6 100644
--- a/android/guava/src/com/google/common/collect/Multimaps.java
+++ b/android/guava/src/com/google/common/collect/Multimaps.java
@@ -19,6 +19,8 @@
 import static com.google.common.base.Preconditions.checkNotNull;
 import static com.google.common.collect.CollectPreconditions.checkNonnegative;
 import static com.google.common.collect.CollectPreconditions.checkRemove;
+import static com.google.common.collect.NullnessCasts.uncheckedCastNullableTToT;
+import static java.util.Objects.requireNonNull;
 
 import com.google.common.annotations.Beta;
 import com.google.common.annotations.GwtCompatible;
@@ -49,13 +51,14 @@
 import java.util.NoSuchElementException;
 import java.util.Set;
 import java.util.SortedSet;
-import org.checkerframework.checker.nullness.compatqual.NullableDecl;
+import javax.annotation.CheckForNull;
+import org.checkerframework.checker.nullness.qual.Nullable;
 
 /**
  * Provides static methods acting on or generating a {@code Multimap}.
  *
  * <p>See the Guava User Guide article on <a href=
- * "https://github.com/google/guava/wiki/CollectionUtilitiesExplained#multimaps"> {@code
+ * "https://github.com/google/guava/wiki/CollectionUtilitiesExplained#multimaps">{@code
  * Multimaps}</a>.
  *
  * @author Jared Levy
@@ -65,6 +68,7 @@
  * @since 2.0
  */
 @GwtCompatible(emulated = true)
+@ElementTypesAreNonnullByDefault
 public final class Multimaps {
   private Multimaps() {}
 
@@ -104,12 +108,13 @@ private Multimaps() {}
    *     key
    * @throws IllegalArgumentException if {@code map} is not empty
    */
-  public static <K, V> Multimap<K, V> newMultimap(
+  public static <K extends @Nullable Object, V extends @Nullable Object> Multimap<K, V> newMultimap(
       Map<K, Collection<V>> map, final Supplier<? extends Collection<V>> factory) {
     return new CustomMultimap<>(map, factory);
   }
 
-  private static class CustomMultimap<K, V> extends AbstractMapBasedMultimap<K, V> {
+  private static class CustomMultimap<K extends @Nullable Object, V extends @Nullable Object>
+      extends AbstractMapBasedMultimap<K, V> {
     transient Supplier<? extends Collection<V>> factory;
 
     CustomMultimap(Map<K, Collection<V>> map, Supplier<? extends Collection<V>> factory) {
@@ -133,7 +138,8 @@ protected Collection<V> createCollection() {
     }
 
     @Override
-    <E> Collection<E> unmodifiableCollectionSubclass(Collection<E> collection) {
+    <E extends @Nullable Object> Collection<E> unmodifiableCollectionSubclass(
+        Collection<E> collection) {
       if (collection instanceof NavigableSet) {
         return Sets.unmodifiableNavigableSet((NavigableSet<E>) collection);
       } else if (collection instanceof SortedSet) {
@@ -148,7 +154,7 @@ <E> Collection<E> unmodifiableCollectionSubclass(Collection<E> collection) {
     }
 
     @Override
-    Collection<V> wrapCollection(K key, Collection<V> collection) {
+    Collection<V> wrapCollection(@ParametricNullness K key, Collection<V> collection) {
       if (collection instanceof List) {
         return wrapList(key, (List<V>) collection, null);
       } else if (collection instanceof NavigableSet) {
@@ -216,12 +222,14 @@ private void readObject(ObjectInputStream stream) throws IOException, ClassNotFo
    * @param factory supplier of new, empty lists that will each hold all values for a given key
    * @throws IllegalArgumentException if {@code map} is not empty
    */
-  public static <K, V> ListMultimap<K, V> newListMultimap(
-      Map<K, Collection<V>> map, final Supplier<? extends List<V>> factory) {
+  public static <K extends @Nullable Object, V extends @Nullable Object>
+      ListMultimap<K, V> newListMultimap(
+          Map<K, Collection<V>> map, final Supplier<? extends List<V>> factory) {
     return new CustomListMultimap<>(map, factory);
   }
 
-  private static class CustomListMultimap<K, V> extends AbstractListMultimap<K, V> {
+  private static class CustomListMultimap<K extends @Nullable Object, V extends @Nullable Object>
+      extends AbstractListMultimap<K, V> {
     transient Supplier<? extends List<V>> factory;
 
     CustomListMultimap(Map<K, Collection<V>> map, Supplier<? extends List<V>> factory) {
@@ -294,12 +302,14 @@ private void readObject(ObjectInputStream stream) throws IOException, ClassNotFo
    * @param factory supplier of new, empty sets that will each hold all values for a given key
    * @throws IllegalArgumentException if {@code map} is not empty
    */
-  public static <K, V> SetMultimap<K, V> newSetMultimap(
-      Map<K, Collection<V>> map, final Supplier<? extends Set<V>> factory) {
+  public static <K extends @Nullable Object, V extends @Nullable Object>
+      SetMultimap<K, V> newSetMultimap(
+          Map<K, Collection<V>> map, final Supplier<? extends Set<V>> factory) {
     return new CustomSetMultimap<>(map, factory);
   }
 
-  private static class CustomSetMultimap<K, V> extends AbstractSetMultimap<K, V> {
+  private static class CustomSetMultimap<K extends @Nullable Object, V extends @Nullable Object>
+      extends AbstractSetMultimap<K, V> {
     transient Supplier<? extends Set<V>> factory;
 
     CustomSetMultimap(Map<K, Collection<V>> map, Supplier<? extends Set<V>> factory) {
@@ -323,7 +333,8 @@ protected Set<V> createCollection() {
     }
 
     @Override
-    <E> Collection<E> unmodifiableCollectionSubclass(Collection<E> collection) {
+    <E extends @Nullable Object> Collection<E> unmodifiableCollectionSubclass(
+        Collection<E> collection) {
       if (collection instanceof NavigableSet) {
         return Sets.unmodifiableNavigableSet((NavigableSet<E>) collection);
       } else if (collection instanceof SortedSet) {
@@ -334,7 +345,7 @@ <E> Collection<E> unmodifiableCollectionSubclass(Collection<E> collection) {
     }
 
     @Override
-    Collection<V> wrapCollection(K key, Collection<V> collection) {
+    Collection<V> wrapCollection(@ParametricNullness K key, Collection<V> collection) {
       if (collection instanceof NavigableSet) {
         return new WrappedNavigableSet(key, (NavigableSet<V>) collection, null);
       } else if (collection instanceof SortedSet) {
@@ -394,14 +405,17 @@ private void readObject(ObjectInputStream stream) throws IOException, ClassNotFo
    *     key
    * @throws IllegalArgumentException if {@code map} is not empty
    */
-  public static <K, V> SortedSetMultimap<K, V> newSortedSetMultimap(
-      Map<K, Collection<V>> map, final Supplier<? extends SortedSet<V>> factory) {
+  public static <K extends @Nullable Object, V extends @Nullable Object>
+      SortedSetMultimap<K, V> newSortedSetMultimap(
+          Map<K, Collection<V>> map, final Supplier<? extends SortedSet<V>> factory) {
     return new CustomSortedSetMultimap<>(map, factory);
   }
 
-  private static class CustomSortedSetMultimap<K, V> extends AbstractSortedSetMultimap<K, V> {
+  private static class CustomSortedSetMultimap<
+          K extends @Nullable Object, V extends @Nullable Object>
+      extends AbstractSortedSetMultimap<K, V> {
     transient Supplier<? extends SortedSet<V>> factory;
-    transient Comparator<? super V> valueComparator;
+    @CheckForNull transient Comparator<? super V> valueComparator;
 
     CustomSortedSetMultimap(Map<K, Collection<V>> map, Supplier<? extends SortedSet<V>> factory) {
       super(map);
@@ -425,6 +439,7 @@ protected SortedSet<V> createCollection() {
     }
 
     @Override
+    @CheckForNull
     public Comparator<? super V> valueComparator() {
       return valueComparator;
     }
@@ -463,8 +478,8 @@ private void readObject(ObjectInputStream stream) throws IOException, ClassNotFo
    * @return {@code dest}
    */
   @CanIgnoreReturnValue
-  public static <K, V, M extends Multimap<K, V>> M invertFrom(
-      Multimap<? extends V, ? extends K> source, M dest) {
+  public static <K extends @Nullable Object, V extends @Nullable Object, M extends Multimap<K, V>>
+      M invertFrom(Multimap<? extends V, ? extends K> source, M dest) {
     checkNotNull(dest);
     for (Map.Entry<? extends V, ? extends K> entry : source.entries()) {
       dest.put(entry.getValue(), entry.getKey());
@@ -504,7 +519,8 @@ public static <K, V, M extends Multimap<K, V>> M invertFrom(
    * @param multimap the multimap to be wrapped in a synchronized view
    * @return a synchronized view of the specified multimap
    */
-  public static <K, V> Multimap<K, V> synchronizedMultimap(Multimap<K, V> multimap) {
+  public static <K extends @Nullable Object, V extends @Nullable Object>
+      Multimap<K, V> synchronizedMultimap(Multimap<K, V> multimap) {
     return Synchronized.multimap(multimap, null);
   }
 
@@ -519,7 +535,8 @@ public static <K, V> Multimap<K, V> synchronizedMultimap(Multimap<K, V> multimap
    * @param delegate the multimap for which an unmodifiable view is to be returned
    * @return an unmodifiable view of the specified multimap
    */
-  public static <K, V> Multimap<K, V> unmodifiableMultimap(Multimap<K, V> delegate) {
+  public static <K extends @Nullable Object, V extends @Nullable Object>
+      Multimap<K, V> unmodifiableMultimap(Multimap<K, V> delegate) {
     if (delegate instanceof UnmodifiableMultimap || delegate instanceof ImmutableMultimap) {
       return delegate;
     }
@@ -537,14 +554,14 @@ public static <K, V> Multimap<K, V> unmodifiableMultimap(ImmutableMultimap<K, V>
     return checkNotNull(delegate);
   }
 
-  private static class UnmodifiableMultimap<K, V> extends ForwardingMultimap<K, V>
-      implements Serializable {
+  private static class UnmodifiableMultimap<K extends @Nullable Object, V extends @Nullable Object>
+      extends ForwardingMultimap<K, V> implements Serializable {
     final Multimap<K, V> delegate;
-    @LazyInit @NullableDecl transient Collection<Entry<K, V>> entries;
-    @LazyInit @NullableDecl transient Multiset<K> keys;
-    @LazyInit @NullableDecl transient Set<K> keySet;
-    @LazyInit @NullableDecl transient Collection<V> values;
-    @LazyInit @NullableDecl transient Map<K, Collection<V>> map;
+    @LazyInit @CheckForNull transient Collection<Entry<K, V>> entries;
+    @LazyInit @CheckForNull transient Multiset<K> keys;
+    @LazyInit @CheckForNull transient Set<K> keySet;
+    @LazyInit @CheckForNull transient Collection<V> values;
+    @LazyInit @CheckForNull transient Map<K, Collection<V>> map;
 
     UnmodifiableMultimap(final Multimap<K, V> delegate) {
       this.delegate = checkNotNull(delegate);
@@ -589,7 +606,7 @@ public Collection<Entry<K, V>> entries() {
     }
 
     @Override
-    public Collection<V> get(K key) {
+    public Collection<V> get(@ParametricNullness K key) {
       return unmodifiableValueCollection(delegate.get(key));
     }
 
@@ -612,12 +629,12 @@ public Set<K> keySet() {
     }
 
     @Override
-    public boolean put(K key, V value) {
+    public boolean put(@ParametricNullness K key, @ParametricNullness V value) {
       throw new UnsupportedOperationException();
     }
 
     @Override
-    public boolean putAll(K key, Iterable<? extends V> values) {
+    public boolean putAll(@ParametricNullness K key, Iterable<? extends V> values) {
       throw new UnsupportedOperationException();
     }
 
@@ -627,17 +644,17 @@ public boolean putAll(Multimap<? extends K, ? extends V> multimap) {
     }
 
     @Override
-    public boolean remove(Object key, Object value) {
+    public boolean remove(@CheckForNull Object key, @CheckForNull Object value) {
       throw new UnsupportedOperationException();
     }
 
     @Override
-    public Collection<V> removeAll(Object key) {
+    public Collection<V> removeAll(@CheckForNull Object key) {
       throw new UnsupportedOperationException();
     }
 
     @Override
-    public Collection<V> replaceValues(K key, Iterable<? extends V> values) {
+    public Collection<V> replaceValues(@ParametricNullness K key, Iterable<? extends V> values) {
       throw new UnsupportedOperationException();
     }
 
@@ -653,8 +670,9 @@ public Collection<V> values() {
     private static final long serialVersionUID = 0;
   }
 
-  private static class UnmodifiableListMultimap<K, V> extends UnmodifiableMultimap<K, V>
-      implements ListMultimap<K, V> {
+  private static class UnmodifiableListMultimap<
+          K extends @Nullable Object, V extends @Nullable Object>
+      extends UnmodifiableMultimap<K, V> implements ListMultimap<K, V> {
     UnmodifiableListMultimap(ListMultimap<K, V> delegate) {
       super(delegate);
     }
@@ -665,25 +683,26 @@ public ListMultimap<K, V> delegate() {
     }
 
     @Override
-    public List<V> get(K key) {
+    public List<V> get(@ParametricNullness K key) {
       return Collections.unmodifiableList(delegate().get(key));
     }
 
     @Override
-    public List<V> removeAll(Object key) {
+    public List<V> removeAll(@CheckForNull Object key) {
       throw new UnsupportedOperationException();
     }
 
     @Override
-    public List<V> replaceValues(K key, Iterable<? extends V> values) {
+    public List<V> replaceValues(@ParametricNullness K key, Iterable<? extends V> values) {
       throw new UnsupportedOperationException();
     }
 
     private static final long serialVersionUID = 0;
   }
 
-  private static class UnmodifiableSetMultimap<K, V> extends UnmodifiableMultimap<K, V>
-      implements SetMultimap<K, V> {
+  private static class UnmodifiableSetMultimap<
+          K extends @Nullable Object, V extends @Nullable Object>
+      extends UnmodifiableMultimap<K, V> implements SetMultimap<K, V> {
     UnmodifiableSetMultimap(SetMultimap<K, V> delegate) {
       super(delegate);
     }
@@ -694,7 +713,7 @@ public SetMultimap<K, V> delegate() {
     }
 
     @Override
-    public Set<V> get(K key) {
+    public Set<V> get(@ParametricNullness K key) {
       /*
        * Note that this doesn't return a SortedSet when delegate is a
        * SortedSetMultiset, unlike (SortedSet<V>) super.get().
@@ -708,20 +727,21 @@ public Set<Map.Entry<K, V>> entries() {
     }
 
     @Override
-    public Set<V> removeAll(Object key) {
+    public Set<V> removeAll(@CheckForNull Object key) {
       throw new UnsupportedOperationException();
     }
 
     @Override
-    public Set<V> replaceValues(K key, Iterable<? extends V> values) {
+    public Set<V> replaceValues(@ParametricNullness K key, Iterable<? extends V> values) {
       throw new UnsupportedOperationException();
     }
 
     private static final long serialVersionUID = 0;
   }
 
-  private static class UnmodifiableSortedSetMultimap<K, V> extends UnmodifiableSetMultimap<K, V>
-      implements SortedSetMultimap<K, V> {
+  private static class UnmodifiableSortedSetMultimap<
+          K extends @Nullable Object, V extends @Nullable Object>
+      extends UnmodifiableSetMultimap<K, V> implements SortedSetMultimap<K, V> {
     UnmodifiableSortedSetMultimap(SortedSetMultimap<K, V> delegate) {
       super(delegate);
     }
@@ -732,21 +752,22 @@ public SortedSetMultimap<K, V> delegate() {
     }
 
     @Override
-    public SortedSet<V> get(K key) {
+    public SortedSet<V> get(@ParametricNullness K key) {
       return Collections.unmodifiableSortedSet(delegate().get(key));
     }
 
     @Override
-    public SortedSet<V> removeAll(Object key) {
+    public SortedSet<V> removeAll(@CheckForNull Object key) {
       throw new UnsupportedOperationException();
     }
 
     @Override
-    public SortedSet<V> replaceValues(K key, Iterable<? extends V> values) {
+    public SortedSet<V> replaceValues(@ParametricNullness K key, Iterable<? extends V> values) {
       throw new UnsupportedOperationException();
     }
 
     @Override
+    @CheckForNull
     public Comparator<? super V> valueComparator() {
       return delegate().valueComparator();
     }
@@ -764,7 +785,8 @@ public Comparator<? super V> valueComparator() {
    * @param multimap the multimap to be wrapped
    * @return a synchronized view of the specified multimap
    */
-  public static <K, V> SetMultimap<K, V> synchronizedSetMultimap(SetMultimap<K, V> multimap) {
+  public static <K extends @Nullable Object, V extends @Nullable Object>
+      SetMultimap<K, V> synchronizedSetMultimap(SetMultimap<K, V> multimap) {
     return Synchronized.setMultimap(multimap, null);
   }
 
@@ -779,7 +801,8 @@ public static <K, V> SetMultimap<K, V> synchronizedSetMultimap(SetMultimap<K, V>
    * @param delegate the multimap for which an unmodifiable view is to be returned
    * @return an unmodifiable view of the specified multimap
    */
-  public static <K, V> SetMultimap<K, V> unmodifiableSetMultimap(SetMultimap<K, V> delegate) {
+  public static <K extends @Nullable Object, V extends @Nullable Object>
+      SetMultimap<K, V> unmodifiableSetMultimap(SetMultimap<K, V> delegate) {
     if (delegate instanceof UnmodifiableSetMultimap || delegate instanceof ImmutableSetMultimap) {
       return delegate;
     }
@@ -809,8 +832,8 @@ public static <K, V> SetMultimap<K, V> unmodifiableSetMultimap(
    * @param multimap the multimap to be wrapped
    * @return a synchronized view of the specified multimap
    */
-  public static <K, V> SortedSetMultimap<K, V> synchronizedSortedSetMultimap(
-      SortedSetMultimap<K, V> multimap) {
+  public static <K extends @Nullable Object, V extends @Nullable Object>
+      SortedSetMultimap<K, V> synchronizedSortedSetMultimap(SortedSetMultimap<K, V> multimap) {
     return Synchronized.sortedSetMultimap(multimap, null);
   }
 
@@ -825,8 +848,8 @@ public static <K, V> SortedSetMultimap<K, V> synchronizedSortedSetMultimap(
    * @param delegate the multimap for which an unmodifiable view is to be returned
    * @return an unmodifiable view of the specified multimap
    */
-  public static <K, V> SortedSetMultimap<K, V> unmodifiableSortedSetMultimap(
-      SortedSetMultimap<K, V> delegate) {
+  public static <K extends @Nullable Object, V extends @Nullable Object>
+      SortedSetMultimap<K, V> unmodifiableSortedSetMultimap(SortedSetMultimap<K, V> delegate) {
     if (delegate instanceof UnmodifiableSortedSetMultimap) {
       return delegate;
     }
@@ -841,7 +864,8 @@ public static <K, V> SortedSetMultimap<K, V> unmodifiableSortedSetMultimap(
    * @param multimap the multimap to be wrapped
    * @return a synchronized view of the specified multimap
    */
-  public static <K, V> ListMultimap<K, V> synchronizedListMultimap(ListMultimap<K, V> multimap) {
+  public static <K extends @Nullable Object, V extends @Nullable Object>
+      ListMultimap<K, V> synchronizedListMultimap(ListMultimap<K, V> multimap) {
     return Synchronized.listMultimap(multimap, null);
   }
 
@@ -856,7 +880,8 @@ public static <K, V> ListMultimap<K, V> synchronizedListMultimap(ListMultimap<K,
    * @param delegate the multimap for which an unmodifiable view is to be returned
    * @return an unmodifiable view of the specified multimap
    */
-  public static <K, V> ListMultimap<K, V> unmodifiableListMultimap(ListMultimap<K, V> delegate) {
+  public static <K extends @Nullable Object, V extends @Nullable Object>
+      ListMultimap<K, V> unmodifiableListMultimap(ListMultimap<K, V> delegate) {
     if (delegate instanceof UnmodifiableListMultimap || delegate instanceof ImmutableListMultimap) {
       return delegate;
     }
@@ -883,7 +908,8 @@ public static <K, V> ListMultimap<K, V> unmodifiableListMultimap(
    * @param collection the collection for which to return an unmodifiable view
    * @return an unmodifiable view of the collection
    */
-  private static <V> Collection<V> unmodifiableValueCollection(Collection<V> collection) {
+  private static <V extends @Nullable Object> Collection<V> unmodifiableValueCollection(
+      Collection<V> collection) {
     if (collection instanceof SortedSet) {
       return Collections.unmodifiableSortedSet((SortedSet<V>) collection);
     } else if (collection instanceof Set) {
@@ -902,8 +928,8 @@ private static <V> Collection<V> unmodifiableValueCollection(Collection<V> colle
    * @param entries the entries for which to return an unmodifiable view
    * @return an unmodifiable view of the entries
    */
-  private static <K, V> Collection<Entry<K, V>> unmodifiableEntries(
-      Collection<Entry<K, V>> entries) {
+  private static <K extends @Nullable Object, V extends @Nullable Object>
+      Collection<Entry<K, V>> unmodifiableEntries(Collection<Entry<K, V>> entries) {
     if (entries instanceof Set) {
       return Maps.unmodifiableEntrySet((Set<Entry<K, V>>) entries);
     }
@@ -919,7 +945,8 @@ private static <K, V> Collection<Entry<K, V>> unmodifiableEntries(
   @Beta
   @SuppressWarnings("unchecked")
   // safe by specification of ListMultimap.asMap()
-  public static <K, V> Map<K, List<V>> asMap(ListMultimap<K, V> multimap) {
+  public static <K extends @Nullable Object, V extends @Nullable Object> Map<K, List<V>> asMap(
+      ListMultimap<K, V> multimap) {
     return (Map<K, List<V>>) (Map<K, ?>) multimap.asMap();
   }
 
@@ -932,7 +959,8 @@ public static <K, V> Map<K, List<V>> asMap(ListMultimap<K, V> multimap) {
   @Beta
   @SuppressWarnings("unchecked")
   // safe by specification of SetMultimap.asMap()
-  public static <K, V> Map<K, Set<V>> asMap(SetMultimap<K, V> multimap) {
+  public static <K extends @Nullable Object, V extends @Nullable Object> Map<K, Set<V>> asMap(
+      SetMultimap<K, V> multimap) {
     return (Map<K, Set<V>>) (Map<K, ?>) multimap.asMap();
   }
 
@@ -945,7 +973,8 @@ public static <K, V> Map<K, Set<V>> asMap(SetMultimap<K, V> multimap) {
   @Beta
   @SuppressWarnings("unchecked")
   // safe by specification of SortedSetMultimap.asMap()
-  public static <K, V> Map<K, SortedSet<V>> asMap(SortedSetMultimap<K, V> multimap) {
+  public static <K extends @Nullable Object, V extends @Nullable Object> Map<K, SortedSet<V>> asMap(
+      SortedSetMultimap<K, V> multimap) {
     return (Map<K, SortedSet<V>>) (Map<K, ?>) multimap.asMap();
   }
 
@@ -956,7 +985,8 @@ public static <K, V> Map<K, SortedSet<V>> asMap(SortedSetMultimap<K, V> multimap
    * @since 15.0
    */
   @Beta
-  public static <K, V> Map<K, Collection<V>> asMap(Multimap<K, V> multimap) {
+  public static <K extends @Nullable Object, V extends @Nullable Object>
+      Map<K, Collection<V>> asMap(Multimap<K, V> multimap) {
     return multimap.asMap();
   }
 
@@ -975,13 +1005,14 @@ public static <K, V> Map<K, Collection<V>> asMap(Multimap<K, V> multimap) {
    *
    * @param map the backing map for the returned multimap view
    */
-  public static <K, V> SetMultimap<K, V> forMap(Map<K, V> map) {
+  public static <K extends @Nullable Object, V extends @Nullable Object> SetMultimap<K, V> forMap(
+      Map<K, V> map) {
     return new MapMultimap<>(map);
   }
 
   /** @see Multimaps#forMap */
-  private static class MapMultimap<K, V> extends AbstractMultimap<K, V>
-      implements SetMultimap<K, V>, Serializable {
+  private static class MapMultimap<K extends @Nullable Object, V extends @Nullable Object>
+      extends AbstractMultimap<K, V> implements SetMultimap<K, V>, Serializable {
     final Map<K, V> map;
 
     MapMultimap(Map<K, V> map) {
@@ -994,22 +1025,22 @@ public int size() {
     }
 
     @Override
-    public boolean containsKey(Object key) {
+    public boolean containsKey(@CheckForNull Object key) {
       return map.containsKey(key);
     }
 
     @Override
-    public boolean containsValue(Object value) {
+    public boolean containsValue(@CheckForNull Object value) {
       return map.containsValue(value);
     }
 
     @Override
-    public boolean containsEntry(Object key, Object value) {
+    public boolean containsEntry(@CheckForNull Object key, @CheckForNull Object value) {
       return map.entrySet().contains(Maps.immutableEntry(key, value));
     }
 
     @Override
-    public Set<V> get(final K key) {
+    public Set<V> get(@ParametricNullness final K key) {
       return new Sets.ImprovedAbstractSet<V>() {
         @Override
         public Iterator<V> iterator() {
@@ -1022,12 +1053,17 @@ public boolean hasNext() {
             }
 
             @Override
+            @ParametricNullness
             public V next() {
               if (!hasNext()) {
                 throw new NoSuchElementException();
               }
               i++;
-              return map.get(key);
+              /*
+               * The cast is safe because of the containsKey check in hasNext(). (That means it's
+               * unsafe under concurrent modification, but all bets are off then, anyway.)
+               */
+              return uncheckedCastNullableTToT(map.get(key));
             }
 
             @Override
@@ -1047,12 +1083,12 @@ public int size() {
     }
 
     @Override
-    public boolean put(K key, V value) {
+    public boolean put(@ParametricNullness K key, @ParametricNullness V value) {
       throw new UnsupportedOperationException();
     }
 
     @Override
-    public boolean putAll(K key, Iterable<? extends V> values) {
+    public boolean putAll(@ParametricNullness K key, Iterable<? extends V> values) {
       throw new UnsupportedOperationException();
     }
 
@@ -1062,17 +1098,17 @@ public boolean putAll(Multimap<? extends K, ? extends V> multimap) {
     }
 
     @Override
-    public Set<V> replaceValues(K key, Iterable<? extends V> values) {
+    public Set<V> replaceValues(@ParametricNullness K key, Iterable<? extends V> values) {
       throw new UnsupportedOperationException();
     }
 
     @Override
-    public boolean remove(Object key, Object value) {
+    public boolean remove(@CheckForNull Object key, @CheckForNull Object value) {
       return map.entrySet().remove(Maps.immutableEntry(key, value));
     }
 
     @Override
-    public Set<V> removeAll(Object key) {
+    public Set<V> removeAll(@CheckForNull Object key) {
       Set<V> values = new HashSet<V>(2);
       if (!map.containsKey(key)) {
         return values;
@@ -1170,8 +1206,10 @@ public int hashCode() {
    *
    * @since 7.0
    */
-  public static <K, V1, V2> Multimap<K, V2> transformValues(
-      Multimap<K, V1> fromMultimap, final Function<? super V1, V2> function) {
+  public static <
+          K extends @Nullable Object, V1 extends @Nullable Object, V2 extends @Nullable Object>
+      Multimap<K, V2> transformValues(
+          Multimap<K, V1> fromMultimap, final Function<? super V1, V2> function) {
     checkNotNull(function);
     EntryTransformer<K, V1, V2> transformer = Maps.asEntryTransformer(function);
     return transformEntries(fromMultimap, transformer);
@@ -1217,8 +1255,10 @@ public static <K, V1, V2> Multimap<K, V2> transformValues(
    *
    * @since 7.0
    */
-  public static <K, V1, V2> ListMultimap<K, V2> transformValues(
-      ListMultimap<K, V1> fromMultimap, final Function<? super V1, V2> function) {
+  public static <
+          K extends @Nullable Object, V1 extends @Nullable Object, V2 extends @Nullable Object>
+      ListMultimap<K, V2> transformValues(
+          ListMultimap<K, V1> fromMultimap, final Function<? super V1, V2> function) {
     checkNotNull(function);
     EntryTransformer<K, V1, V2> transformer = Maps.asEntryTransformer(function);
     return transformEntries(fromMultimap, transformer);
@@ -1275,8 +1315,10 @@ public static <K, V1, V2> ListMultimap<K, V2> transformValues(
    *
    * @since 7.0
    */
-  public static <K, V1, V2> Multimap<K, V2> transformEntries(
-      Multimap<K, V1> fromMap, EntryTransformer<? super K, ? super V1, V2> transformer) {
+  public static <
+          K extends @Nullable Object, V1 extends @Nullable Object, V2 extends @Nullable Object>
+      Multimap<K, V2> transformEntries(
+          Multimap<K, V1> fromMap, EntryTransformer<? super K, ? super V1, V2> transformer) {
     return new TransformedEntriesMultimap<>(fromMap, transformer);
   }
 
@@ -1328,12 +1370,16 @@ public static <K, V1, V2> Multimap<K, V2> transformEntries(
    *
    * @since 7.0
    */
-  public static <K, V1, V2> ListMultimap<K, V2> transformEntries(
-      ListMultimap<K, V1> fromMap, EntryTransformer<? super K, ? super V1, V2> transformer) {
+  public static <
+          K extends @Nullable Object, V1 extends @Nullable Object, V2 extends @Nullable Object>
+      ListMultimap<K, V2> transformEntries(
+          ListMultimap<K, V1> fromMap, EntryTransformer<? super K, ? super V1, V2> transformer) {
     return new TransformedEntriesListMultimap<>(fromMap, transformer);
   }
 
-  private static class TransformedEntriesMultimap<K, V1, V2> extends AbstractMultimap<K, V2> {
+  private static class TransformedEntriesMultimap<
+          K extends @Nullable Object, V1 extends @Nullable Object, V2 extends @Nullable Object>
+      extends AbstractMultimap<K, V2> {
     final Multimap<K, V1> fromMultimap;
     final EntryTransformer<? super K, ? super V1, V2> transformer;
 
@@ -1344,7 +1390,7 @@ private static class TransformedEntriesMultimap<K, V1, V2> extends AbstractMulti
       this.transformer = checkNotNull(transformer);
     }
 
-    Collection<V2> transform(K key, Collection<V1> values) {
+    Collection<V2> transform(@ParametricNullness K key, Collection<V1> values) {
       Function<? super V1, V2> function = Maps.asValueToValueFunction(transformer, key);
       if (values instanceof List) {
         return Lists.transform((List<V1>) values, function);
@@ -1359,7 +1405,7 @@ Map<K, Collection<V2>> createAsMap() {
           fromMultimap.asMap(),
           new EntryTransformer<K, Collection<V1>, Collection<V2>>() {
             @Override
-            public Collection<V2> transformEntry(K key, Collection<V1> value) {
+            public Collection<V2> transformEntry(@ParametricNullness K key, Collection<V1> value) {
               return transform(key, value);
             }
           });
@@ -1371,7 +1417,7 @@ public void clear() {
     }
 
     @Override
-    public boolean containsKey(Object key) {
+    public boolean containsKey(@CheckForNull Object key) {
       return fromMultimap.containsKey(key);
     }
 
@@ -1387,7 +1433,7 @@ Iterator<Entry<K, V2>> entryIterator() {
     }
 
     @Override
-    public Collection<V2> get(final K key) {
+    public Collection<V2> get(@ParametricNullness final K key) {
       return transform(key, fromMultimap.get(key));
     }
 
@@ -1407,12 +1453,12 @@ Multiset<K> createKeys() {
     }
 
     @Override
-    public boolean put(K key, V2 value) {
+    public boolean put(@ParametricNullness K key, @ParametricNullness V2 value) {
       throw new UnsupportedOperationException();
     }
 
     @Override
-    public boolean putAll(K key, Iterable<? extends V2> values) {
+    public boolean putAll(@ParametricNullness K key, Iterable<? extends V2> values) {
       throw new UnsupportedOperationException();
     }
 
@@ -1423,18 +1469,18 @@ public boolean putAll(Multimap<? extends K, ? extends V2> multimap) {
 
     @SuppressWarnings("unchecked")
     @Override
-    public boolean remove(Object key, Object value) {
+    public boolean remove(@CheckForNull Object key, @CheckForNull Object value) {
       return get((K) key).remove(value);
     }
 
     @SuppressWarnings("unchecked")
     @Override
-    public Collection<V2> removeAll(Object key) {
+    public Collection<V2> removeAll(@CheckForNull Object key) {
       return transform((K) key, fromMultimap.removeAll(key));
     }
 
     @Override
-    public Collection<V2> replaceValues(K key, Iterable<? extends V2> values) {
+    public Collection<V2> replaceValues(@ParametricNullness K key, Iterable<? extends V2> values) {
       throw new UnsupportedOperationException();
     }
 
@@ -1450,7 +1496,8 @@ Collection<V2> createValues() {
     }
   }
 
-  private static final class TransformedEntriesListMultimap<K, V1, V2>
+  private static final class TransformedEntriesListMultimap<
+          K extends @Nullable Object, V1 extends @Nullable Object, V2 extends @Nullable Object>
       extends TransformedEntriesMultimap<K, V1, V2> implements ListMultimap<K, V2> {
 
     TransformedEntriesListMultimap(
@@ -1459,23 +1506,23 @@ private static final class TransformedEntriesListMultimap<K, V1, V2>
     }
 
     @Override
-    List<V2> transform(K key, Collection<V1> values) {
+    List<V2> transform(@ParametricNullness K key, Collection<V1> values) {
       return Lists.transform((List<V1>) values, Maps.asValueToValueFunction(transformer, key));
     }
 
     @Override
-    public List<V2> get(K key) {
+    public List<V2> get(@ParametricNullness K key) {
       return transform(key, fromMultimap.get(key));
     }
 
     @SuppressWarnings("unchecked")
     @Override
-    public List<V2> removeAll(Object key) {
+    public List<V2> removeAll(@CheckForNull Object key) {
       return transform((K) key, fromMultimap.removeAll(key));
     }
 
     @Override
-    public List<V2> replaceValues(K key, Iterable<? extends V2> values) {
+    public List<V2> replaceValues(@ParametricNullness K key, Iterable<? extends V2> values) {
       throw new UnsupportedOperationException();
     }
   }
@@ -1568,7 +1615,8 @@ public static <K, V> ImmutableListMultimap<K, V> index(
     return builder.build();
   }
 
-  static class Keys<K, V> extends AbstractMultiset<K> {
+  static class Keys<K extends @Nullable Object, V extends @Nullable Object>
+      extends AbstractMultiset<K> {
     @Weak final Multimap<K, V> multimap;
 
     Keys(Multimap<K, V> multimap) {
@@ -1583,6 +1631,7 @@ Iterator<Multiset.Entry<K>> entryIterator() {
         Multiset.Entry<K> transform(final Map.Entry<K, Collection<V>> backingEntry) {
           return new Multisets.AbstractEntry<K>() {
             @Override
+            @ParametricNullness
             public K getElement() {
               return backingEntry.getKey();
             }
@@ -1607,7 +1656,7 @@ public int size() {
     }
 
     @Override
-    public boolean contains(@NullableDecl Object element) {
+    public boolean contains(@CheckForNull Object element) {
       return multimap.containsKey(element);
     }
 
@@ -1617,13 +1666,13 @@ public Iterator<K> iterator() {
     }
 
     @Override
-    public int count(@NullableDecl Object element) {
+    public int count(@CheckForNull Object element) {
       Collection<V> values = Maps.safeGet(multimap.asMap(), element);
       return (values == null) ? 0 : values.size();
     }
 
     @Override
-    public int remove(@NullableDecl Object element, int occurrences) {
+    public int remove(@CheckForNull Object element, int occurrences) {
       checkNonnegative(occurrences, "occurrences");
       if (occurrences == 0) {
         return count(element);
@@ -1665,7 +1714,8 @@ Iterator<K> elementIterator() {
   }
 
   /** A skeleton implementation of {@link Multimap#entries()}. */
-  abstract static class Entries<K, V> extends AbstractCollection<Map.Entry<K, V>> {
+  abstract static class Entries<K extends @Nullable Object, V extends @Nullable Object>
+      extends AbstractCollection<Map.Entry<K, V>> {
     abstract Multimap<K, V> multimap();
 
     @Override
@@ -1674,7 +1724,7 @@ public int size() {
     }
 
     @Override
-    public boolean contains(@NullableDecl Object o) {
+    public boolean contains(@CheckForNull Object o) {
       if (o instanceof Map.Entry) {
         Map.Entry<?, ?> entry = (Map.Entry<?, ?>) o;
         return multimap().containsEntry(entry.getKey(), entry.getValue());
@@ -1683,7 +1733,7 @@ public boolean contains(@NullableDecl Object o) {
     }
 
     @Override
-    public boolean remove(@NullableDecl Object o) {
+    public boolean remove(@CheckForNull Object o) {
       if (o instanceof Map.Entry) {
         Map.Entry<?, ?> entry = (Map.Entry<?, ?>) o;
         return multimap().remove(entry.getKey(), entry.getValue());
@@ -1698,7 +1748,8 @@ public void clear() {
   }
 
   /** A skeleton implementation of {@link Multimap#asMap()}. */
-  static final class AsMap<K, V> extends Maps.ViewCachingAbstractMap<K, Collection<V>> {
+  static final class AsMap<K extends @Nullable Object, V extends @Nullable Object>
+      extends Maps.ViewCachingAbstractMap<K, Collection<V>> {
     @Weak private final Multimap<K, V> multimap;
 
     AsMap(Multimap<K, V> multimap) {
@@ -1715,7 +1766,7 @@ protected Set<Entry<K, Collection<V>>> createEntrySet() {
       return new EntrySet();
     }
 
-    void removeValuesForKey(Object key) {
+    void removeValuesForKey(@CheckForNull Object key) {
       multimap.keySet().remove(key);
     }
 
@@ -1732,18 +1783,19 @@ public Iterator<Entry<K, Collection<V>>> iterator() {
             multimap.keySet(),
             new Function<K, Collection<V>>() {
               @Override
-              public Collection<V> apply(K key) {
+              public Collection<V> apply(@ParametricNullness K key) {
                 return multimap.get(key);
               }
             });
       }
 
       @Override
-      public boolean remove(Object o) {
+      public boolean remove(@CheckForNull Object o) {
         if (!contains(o)) {
           return false;
         }
-        Map.Entry<?, ?> entry = (Map.Entry<?, ?>) o;
+        // requireNonNull is safe because of the contains check.
+        Map.Entry<?, ?> entry = requireNonNull((Map.Entry<?, ?>) o);
         removeValuesForKey(entry.getKey());
         return true;
       }
@@ -1751,12 +1803,14 @@ public boolean remove(Object o) {
 
     @SuppressWarnings("unchecked")
     @Override
-    public Collection<V> get(Object key) {
+    @CheckForNull
+    public Collection<V> get(@CheckForNull Object key) {
       return containsKey(key) ? multimap.get((K) key) : null;
     }
 
     @Override
-    public Collection<V> remove(Object key) {
+    @CheckForNull
+    public Collection<V> remove(@CheckForNull Object key) {
       return containsKey(key) ? multimap.removeAll(key) : null;
     }
 
@@ -1771,7 +1825,7 @@ public boolean isEmpty() {
     }
 
     @Override
-    public boolean containsKey(Object key) {
+    public boolean containsKey(@CheckForNull Object key) {
       return multimap.containsKey(key);
     }
 
@@ -1808,7 +1862,7 @@ public void clear() {
    *
    * @since 11.0
    */
-  public static <K, V> Multimap<K, V> filterKeys(
+  public static <K extends @Nullable Object, V extends @Nullable Object> Multimap<K, V> filterKeys(
       Multimap<K, V> unfiltered, final Predicate<? super K> keyPredicate) {
     if (unfiltered instanceof SetMultimap) {
       return filterKeys((SetMultimap<K, V>) unfiltered, keyPredicate);
@@ -1853,8 +1907,9 @@ public static <K, V> Multimap<K, V> filterKeys(
    *
    * @since 14.0
    */
-  public static <K, V> SetMultimap<K, V> filterKeys(
-      SetMultimap<K, V> unfiltered, final Predicate<? super K> keyPredicate) {
+  public static <K extends @Nullable Object, V extends @Nullable Object>
+      SetMultimap<K, V> filterKeys(
+          SetMultimap<K, V> unfiltered, final Predicate<? super K> keyPredicate) {
     if (unfiltered instanceof FilteredKeySetMultimap) {
       FilteredKeySetMultimap<K, V> prev = (FilteredKeySetMultimap<K, V>) unfiltered;
       return new FilteredKeySetMultimap<>(
@@ -1894,8 +1949,9 @@ public static <K, V> SetMultimap<K, V> filterKeys(
    *
    * @since 14.0
    */
-  public static <K, V> ListMultimap<K, V> filterKeys(
-      ListMultimap<K, V> unfiltered, final Predicate<? super K> keyPredicate) {
+  public static <K extends @Nullable Object, V extends @Nullable Object>
+      ListMultimap<K, V> filterKeys(
+          ListMultimap<K, V> unfiltered, final Predicate<? super K> keyPredicate) {
     if (unfiltered instanceof FilteredKeyListMultimap) {
       FilteredKeyListMultimap<K, V> prev = (FilteredKeyListMultimap<K, V>) unfiltered;
       return new FilteredKeyListMultimap<>(
@@ -1932,8 +1988,9 @@ public static <K, V> ListMultimap<K, V> filterKeys(
    *
    * @since 11.0
    */
-  public static <K, V> Multimap<K, V> filterValues(
-      Multimap<K, V> unfiltered, final Predicate<? super V> valuePredicate) {
+  public static <K extends @Nullable Object, V extends @Nullable Object>
+      Multimap<K, V> filterValues(
+          Multimap<K, V> unfiltered, final Predicate<? super V> valuePredicate) {
     return filterEntries(unfiltered, Maps.<V>valuePredicateOnEntries(valuePredicate));
   }
 
@@ -1964,8 +2021,9 @@ public static <K, V> Multimap<K, V> filterValues(
    *
    * @since 14.0
    */
-  public static <K, V> SetMultimap<K, V> filterValues(
-      SetMultimap<K, V> unfiltered, final Predicate<? super V> valuePredicate) {
+  public static <K extends @Nullable Object, V extends @Nullable Object>
+      SetMultimap<K, V> filterValues(
+          SetMultimap<K, V> unfiltered, final Predicate<? super V> valuePredicate) {
     return filterEntries(unfiltered, Maps.<V>valuePredicateOnEntries(valuePredicate));
   }
 
@@ -1994,8 +2052,9 @@ public static <K, V> SetMultimap<K, V> filterValues(
    *
    * @since 11.0
    */
-  public static <K, V> Multimap<K, V> filterEntries(
-      Multimap<K, V> unfiltered, Predicate<? super Entry<K, V>> entryPredicate) {
+  public static <K extends @Nullable Object, V extends @Nullable Object>
+      Multimap<K, V> filterEntries(
+          Multimap<K, V> unfiltered, Predicate<? super Entry<K, V>> entryPredicate) {
     checkNotNull(entryPredicate);
     if (unfiltered instanceof SetMultimap) {
       return filterEntries((SetMultimap<K, V>) unfiltered, entryPredicate);
@@ -2030,8 +2089,9 @@ public static <K, V> Multimap<K, V> filterEntries(
    *
    * @since 14.0
    */
-  public static <K, V> SetMultimap<K, V> filterEntries(
-      SetMultimap<K, V> unfiltered, Predicate<? super Entry<K, V>> entryPredicate) {
+  public static <K extends @Nullable Object, V extends @Nullable Object>
+      SetMultimap<K, V> filterEntries(
+          SetMultimap<K, V> unfiltered, Predicate<? super Entry<K, V>> entryPredicate) {
     checkNotNull(entryPredicate);
     return (unfiltered instanceof FilteredSetMultimap)
         ? filterFiltered((FilteredSetMultimap<K, V>) unfiltered, entryPredicate)
@@ -2044,8 +2104,9 @@ public static <K, V> SetMultimap<K, V> filterEntries(
    * lead to a multimap whose removal operations would fail. This method combines the predicates to
    * avoid that problem.
    */
-  private static <K, V> Multimap<K, V> filterFiltered(
-      FilteredMultimap<K, V> multimap, Predicate<? super Entry<K, V>> entryPredicate) {
+  private static <K extends @Nullable Object, V extends @Nullable Object>
+      Multimap<K, V> filterFiltered(
+          FilteredMultimap<K, V> multimap, Predicate<? super Entry<K, V>> entryPredicate) {
     Predicate<Entry<K, V>> predicate =
         Predicates.<Entry<K, V>>and(multimap.entryPredicate(), entryPredicate);
     return new FilteredEntryMultimap<>(multimap.unfiltered(), predicate);
@@ -2057,14 +2118,15 @@ private static <K, V> Multimap<K, V> filterFiltered(
    * lead to a multimap whose removal operations would fail. This method combines the predicates to
    * avoid that problem.
    */
-  private static <K, V> SetMultimap<K, V> filterFiltered(
-      FilteredSetMultimap<K, V> multimap, Predicate<? super Entry<K, V>> entryPredicate) {
+  private static <K extends @Nullable Object, V extends @Nullable Object>
+      SetMultimap<K, V> filterFiltered(
+          FilteredSetMultimap<K, V> multimap, Predicate<? super Entry<K, V>> entryPredicate) {
     Predicate<Entry<K, V>> predicate =
         Predicates.<Entry<K, V>>and(multimap.entryPredicate(), entryPredicate);
     return new FilteredEntrySetMultimap<>(multimap.unfiltered(), predicate);
   }
 
-  static boolean equalsImpl(Multimap<?, ?> multimap, @NullableDecl Object object) {
+  static boolean equalsImpl(Multimap<?, ?> multimap, @CheckForNull Object object) {
     if (object == multimap) {
       return true;
     }
diff --git a/android/guava/src/com/google/common/collect/Multiset.java b/android/guava/src/com/google/common/collect/Multiset.java
index faedb56071e5..f60046fa4f69 100644
--- a/android/guava/src/com/google/common/collect/Multiset.java
+++ b/android/guava/src/com/google/common/collect/Multiset.java
@@ -24,7 +24,8 @@
 import java.util.Iterator;
 import java.util.List;
 import java.util.Set;
-import org.checkerframework.checker.nullness.compatqual.NullableDecl;
+import javax.annotation.CheckForNull;
+import org.checkerframework.checker.nullness.qual.Nullable;
 
 /**
  * A collection that supports order-independent equality, like {@link Set}, but may have duplicate
@@ -61,6 +62,10 @@
  * <p>A multiset uses {@link Object#equals} to determine whether two instances should be considered
  * "the same," <i>unless specified otherwise</i> by the implementation.
  *
+ * <p><b>Warning:</b> as with normal {@link Set}s, it is almost always a bad idea to modify an
+ * element (in a way that affects its {@link Object#equals} behavior) while it is contained in a
+ * multiset. Undefined behavior and bugs will result.
+ *
  * <p>Common implementations include {@link ImmutableMultiset}, {@link HashMultiset}, and {@link
  * ConcurrentHashMultiset}.
  *
@@ -69,14 +74,14 @@
  * {@code Multiset}, {@code AtomicLongMap} does not automatically remove zeros.
  *
  * <p>See the Guava User Guide article on <a href=
- * "https://github.com/google/guava/wiki/NewCollectionTypesExplained#multiset"> {@code
- * Multiset}</a>.
+ * "https://github.com/google/guava/wiki/NewCollectionTypesExplained#multiset">{@code Multiset}</a>.
  *
  * @author Kevin Bourrillion
  * @since 2.0
  */
 @GwtCompatible
-public interface Multiset<E> extends Collection<E> {
+@ElementTypesAreNonnullByDefault
+public interface Multiset<E extends @Nullable Object> extends Collection<E> {
   // Query Operations
 
   /**
@@ -101,7 +106,7 @@ public interface Multiset<E> extends Collection<E> {
    * @return the number of occurrences of the element in this multiset; possibly zero but never
    *     negative
    */
-  int count(@NullableDecl @CompatibleWith("E") Object element);
+  int count(@CompatibleWith("E") @CheckForNull Object element);
 
   // Bulk Operations
 
@@ -124,7 +129,7 @@ public interface Multiset<E> extends Collection<E> {
    *     return normally.
    */
   @CanIgnoreReturnValue
-  int add(@NullableDecl E element, int occurrences);
+  int add(@ParametricNullness E element, int occurrences);
 
   /**
    * Adds a single occurrence of the specified element to this multiset.
@@ -147,7 +152,7 @@ public interface Multiset<E> extends Collection<E> {
    */
   @CanIgnoreReturnValue
   @Override
-  boolean add(E element);
+  boolean add(@ParametricNullness E element);
 
   /**
    * Removes a number of occurrences of the specified element from this multiset. If the multiset
@@ -162,7 +167,7 @@ public interface Multiset<E> extends Collection<E> {
    * @throws IllegalArgumentException if {@code occurrences} is negative
    */
   @CanIgnoreReturnValue
-  int remove(@NullableDecl @CompatibleWith("E") Object element, int occurrences);
+  int remove(@CompatibleWith("E") @CheckForNull Object element, int occurrences);
 
   /**
    * Removes a <i>single</i> occurrence of the specified element from this multiset, if present.
@@ -178,7 +183,7 @@ public interface Multiset<E> extends Collection<E> {
    */
   @CanIgnoreReturnValue
   @Override
-  boolean remove(@NullableDecl Object element);
+  boolean remove(@CheckForNull Object element);
 
   /**
    * Adds or removes the necessary occurrences of an element such that the element attains the
@@ -194,7 +199,7 @@ public interface Multiset<E> extends Collection<E> {
    *     zero instead.
    */
   @CanIgnoreReturnValue
-  int setCount(E element, int count);
+  int setCount(@ParametricNullness E element, int count);
 
   /**
    * Conditionally sets the count of an element to a new value, as described in {@link
@@ -213,7 +218,7 @@ public interface Multiset<E> extends Collection<E> {
    *     implementor may optionally return {@code true} instead.
    */
   @CanIgnoreReturnValue
-  boolean setCount(E element, int oldCount, int newCount);
+  boolean setCount(@ParametricNullness E element, int oldCount, int newCount);
 
   // Views
 
@@ -259,7 +264,7 @@ public interface Multiset<E> extends Collection<E> {
    *
    * @since 2.0
    */
-  interface Entry<E> {
+  interface Entry<E extends @Nullable Object> {
 
     /**
      * Returns the multiset element corresponding to this entry. Multiple calls to this method
@@ -267,6 +272,7 @@ interface Entry<E> {
      *
      * @return the element corresponding to this entry
      */
+    @ParametricNullness
     E getElement();
 
     /**
@@ -294,7 +300,7 @@ interface Entry<E> {
      */
     @Override
     // TODO(kevinb): check this wrt TreeMultiset?
-    boolean equals(Object o);
+    boolean equals(@CheckForNull Object o);
 
     /**
      * {@inheritDoc}
@@ -328,7 +334,7 @@ interface Entry<E> {
    */
   @Override
   // TODO(kevinb): caveats about equivalence-relation?
-  boolean equals(@NullableDecl Object object);
+  boolean equals(@CheckForNull Object object);
 
   /**
    * Returns the hash code for this multiset. This is defined as the sum of
@@ -374,7 +380,7 @@ interface Entry<E> {
    * @return {@code true} if this multiset contains at least one occurrence of the element
    */
   @Override
-  boolean contains(@NullableDecl Object element);
+  boolean contains(@CheckForNull Object element);
 
   /**
    * Returns {@code true} if this multiset contains at least one occurrence of each element in the
diff --git a/android/guava/src/com/google/common/collect/Multisets.java b/android/guava/src/com/google/common/collect/Multisets.java
index 0f31b7420e45..a9bcb04289e9 100644
--- a/android/guava/src/com/google/common/collect/Multisets.java
+++ b/android/guava/src/com/google/common/collect/Multisets.java
@@ -20,6 +20,7 @@
 import static com.google.common.base.Preconditions.checkNotNull;
 import static com.google.common.collect.CollectPreconditions.checkNonnegative;
 import static com.google.common.collect.CollectPreconditions.checkRemove;
+import static java.util.Objects.requireNonNull;
 
 import com.google.common.annotations.Beta;
 import com.google.common.annotations.GwtCompatible;
@@ -38,13 +39,14 @@
 import java.util.Iterator;
 import java.util.NoSuchElementException;
 import java.util.Set;
-import org.checkerframework.checker.nullness.compatqual.NullableDecl;
+import javax.annotation.CheckForNull;
+import org.checkerframework.checker.nullness.qual.Nullable;
 
 /**
  * Provides static utility methods for creating and working with {@link Multiset} instances.
  *
  * <p>See the Guava User Guide article on <a href=
- * "https://github.com/google/guava/wiki/CollectionUtilitiesExplained#multisets"> {@code
+ * "https://github.com/google/guava/wiki/CollectionUtilitiesExplained#multisets">{@code
  * Multisets}</a>.
  *
  * @author Kevin Bourrillion
@@ -53,6 +55,7 @@
  * @since 2.0
  */
 @GwtCompatible
+@ElementTypesAreNonnullByDefault
 public final class Multisets {
   private Multisets() {}
 
@@ -66,7 +69,8 @@ private Multisets() {}
    * @param multiset the multiset for which an unmodifiable view is to be generated
    * @return an unmodifiable view of the multiset
    */
-  public static <E> Multiset<E> unmodifiableMultiset(Multiset<? extends E> multiset) {
+  public static <E extends @Nullable Object> Multiset<E> unmodifiableMultiset(
+      Multiset<? extends E> multiset) {
     if (multiset instanceof UnmodifiableMultiset || multiset instanceof ImmutableMultiset) {
       @SuppressWarnings("unchecked") // Since it's unmodifiable, the covariant cast is safe
       Multiset<E> result = (Multiset<E>) multiset;
@@ -86,7 +90,8 @@ public static <E> Multiset<E> unmodifiableMultiset(ImmutableMultiset<E> multiset
     return checkNotNull(multiset);
   }
 
-  static class UnmodifiableMultiset<E> extends ForwardingMultiset<E> implements Serializable {
+  static class UnmodifiableMultiset<E extends @Nullable Object> extends ForwardingMultiset<E>
+      implements Serializable {
     final Multiset<? extends E> delegate;
 
     UnmodifiableMultiset(Multiset<? extends E> delegate) {
@@ -100,7 +105,7 @@ protected Multiset<E> delegate() {
       return (Multiset<E>) delegate;
     }
 
-    @NullableDecl transient Set<E> elementSet;
+    @CheckForNull transient Set<E> elementSet;
 
     Set<E> createElementSet() {
       return Collections.<E>unmodifiableSet(delegate.elementSet());
@@ -112,7 +117,7 @@ public Set<E> elementSet() {
       return (es == null) ? elementSet = createElementSet() : es;
     }
 
-    @NullableDecl transient Set<Multiset.Entry<E>> entrySet;
+    @CheckForNull transient Set<Multiset.Entry<E>> entrySet;
 
     @SuppressWarnings("unchecked")
     @Override
@@ -131,12 +136,12 @@ public Iterator<E> iterator() {
     }
 
     @Override
-    public boolean add(E element) {
+    public boolean add(@ParametricNullness E element) {
       throw new UnsupportedOperationException();
     }
 
     @Override
-    public int add(E element, int occurences) {
+    public int add(@ParametricNullness E element, int occurrences) {
       throw new UnsupportedOperationException();
     }
 
@@ -146,12 +151,12 @@ public boolean addAll(Collection<? extends E> elementsToAdd) {
     }
 
     @Override
-    public boolean remove(Object element) {
+    public boolean remove(@CheckForNull Object element) {
       throw new UnsupportedOperationException();
     }
 
     @Override
-    public int remove(Object element, int occurrences) {
+    public int remove(@CheckForNull Object element, int occurrences) {
       throw new UnsupportedOperationException();
     }
 
@@ -171,12 +176,12 @@ public void clear() {
     }
 
     @Override
-    public int setCount(E element, int count) {
+    public int setCount(@ParametricNullness E element, int count) {
       throw new UnsupportedOperationException();
     }
 
     @Override
-    public boolean setCount(E element, int oldCount, int newCount) {
+    public boolean setCount(@ParametricNullness E element, int oldCount, int newCount) {
       throw new UnsupportedOperationException();
     }
 
@@ -195,7 +200,8 @@ public boolean setCount(E element, int oldCount, int newCount) {
    * @since 11.0
    */
   @Beta
-  public static <E> SortedMultiset<E> unmodifiableSortedMultiset(SortedMultiset<E> sortedMultiset) {
+  public static <E extends @Nullable Object> SortedMultiset<E> unmodifiableSortedMultiset(
+      SortedMultiset<E> sortedMultiset) {
     // it's in its own file so it can be emulated for GWT
     return new UnmodifiableSortedMultiset<E>(checkNotNull(sortedMultiset));
   }
@@ -208,22 +214,24 @@ public static <E> SortedMultiset<E> unmodifiableSortedMultiset(SortedMultiset<E>
    * @param n the count to be associated with the returned entry
    * @throws IllegalArgumentException if {@code n} is negative
    */
-  public static <E> Multiset.Entry<E> immutableEntry(@NullableDecl E e, int n) {
+  public static <E extends @Nullable Object> Multiset.Entry<E> immutableEntry(
+      @ParametricNullness E e, int n) {
     return new ImmutableEntry<E>(e, n);
   }
 
-  static class ImmutableEntry<E> extends AbstractEntry<E> implements Serializable {
-    @NullableDecl private final E element;
+  static class ImmutableEntry<E extends @Nullable Object> extends AbstractEntry<E>
+      implements Serializable {
+    @ParametricNullness private final E element;
     private final int count;
 
-    ImmutableEntry(@NullableDecl E element, int count) {
+    ImmutableEntry(@ParametricNullness E element, int count) {
       this.element = element;
       this.count = count;
       checkNonnegative(count, "count");
     }
 
     @Override
-    @NullableDecl
+    @ParametricNullness
     public final E getElement() {
       return element;
     }
@@ -233,6 +241,7 @@ public final int getCount() {
       return count;
     }
 
+    @CheckForNull
     public ImmutableEntry<E> nextInBucket() {
       return null;
     }
@@ -266,7 +275,8 @@ public ImmutableEntry<E> nextInBucket() {
    * @since 14.0
    */
   @Beta
-  public static <E> Multiset<E> filter(Multiset<E> unfiltered, Predicate<? super E> predicate) {
+  public static <E extends @Nullable Object> Multiset<E> filter(
+      Multiset<E> unfiltered, Predicate<? super E> predicate) {
     if (unfiltered instanceof FilteredMultiset) {
       // Support clear(), removeAll(), and retainAll() when filtering a filtered
       // collection.
@@ -277,7 +287,7 @@ public static <E> Multiset<E> filter(Multiset<E> unfiltered, Predicate<? super E
     return new FilteredMultiset<E>(unfiltered, predicate);
   }
 
-  private static final class FilteredMultiset<E> extends ViewMultiset<E> {
+  private static final class FilteredMultiset<E extends @Nullable Object> extends ViewMultiset<E> {
     final Multiset<E> unfiltered;
     final Predicate<? super E> predicate;
 
@@ -319,7 +329,7 @@ Iterator<Entry<E>> entryIterator() {
     }
 
     @Override
-    public int count(@NullableDecl Object element) {
+    public int count(@CheckForNull Object element) {
       int count = unfiltered.count(element);
       if (count > 0) {
         @SuppressWarnings("unchecked") // element is equal to an E
@@ -330,14 +340,14 @@ public int count(@NullableDecl Object element) {
     }
 
     @Override
-    public int add(@NullableDecl E element, int occurrences) {
+    public int add(@ParametricNullness E element, int occurrences) {
       checkArgument(
           predicate.apply(element), "Element %s does not match predicate %s", element, predicate);
       return unfiltered.add(element, occurrences);
     }
 
     @Override
-    public int remove(@NullableDecl Object element, int occurrences) {
+    public int remove(@CheckForNull Object element, int occurrences) {
       checkNonnegative(occurrences, "occurrences");
       if (occurrences == 0) {
         return count(element);
@@ -372,14 +382,14 @@ static int inferDistinctElements(Iterable<?> elements) {
    * @since 14.0
    */
   @Beta
-  public static <E> Multiset<E> union(
+  public static <E extends @Nullable Object> Multiset<E> union(
       final Multiset<? extends E> multiset1, final Multiset<? extends E> multiset2) {
     checkNotNull(multiset1);
     checkNotNull(multiset2);
 
     return new ViewMultiset<E>() {
       @Override
-      public boolean contains(@NullableDecl Object element) {
+      public boolean contains(@CheckForNull Object element) {
         return multiset1.contains(element) || multiset2.contains(element);
       }
 
@@ -389,7 +399,7 @@ public boolean isEmpty() {
       }
 
       @Override
-      public int count(Object element) {
+      public int count(@CheckForNull Object element) {
         return Math.max(multiset1.count(element), multiset2.count(element));
       }
 
@@ -410,6 +420,7 @@ Iterator<Entry<E>> entryIterator() {
         // TODO(lowasser): consider making the entries live views
         return new AbstractIterator<Entry<E>>() {
           @Override
+          @CheckForNull
           protected Entry<E> computeNext() {
             if (iterator1.hasNext()) {
               Entry<? extends E> entry1 = iterator1.next();
@@ -443,14 +454,14 @@ protected Entry<E> computeNext() {
    *
    * @since 2.0
    */
-  public static <E> Multiset<E> intersection(
+  public static <E extends @Nullable Object> Multiset<E> intersection(
       final Multiset<E> multiset1, final Multiset<?> multiset2) {
     checkNotNull(multiset1);
     checkNotNull(multiset2);
 
     return new ViewMultiset<E>() {
       @Override
-      public int count(Object element) {
+      public int count(@CheckForNull Object element) {
         int count1 = multiset1.count(element);
         return (count1 == 0) ? 0 : Math.min(count1, multiset2.count(element));
       }
@@ -471,6 +482,7 @@ Iterator<Entry<E>> entryIterator() {
         // TODO(lowasser): consider making the entries live views
         return new AbstractIterator<Entry<E>>() {
           @Override
+          @CheckForNull
           protected Entry<E> computeNext() {
             while (iterator1.hasNext()) {
               Entry<E> entry1 = iterator1.next();
@@ -500,7 +512,7 @@ protected Entry<E> computeNext() {
    * @since 14.0
    */
   @Beta
-  public static <E> Multiset<E> sum(
+  public static <E extends @Nullable Object> Multiset<E> sum(
       final Multiset<? extends E> multiset1, final Multiset<? extends E> multiset2) {
     checkNotNull(multiset1);
     checkNotNull(multiset2);
@@ -508,7 +520,7 @@ public static <E> Multiset<E> sum(
     // TODO(lowasser): consider making the entries live views
     return new ViewMultiset<E>() {
       @Override
-      public boolean contains(@NullableDecl Object element) {
+      public boolean contains(@CheckForNull Object element) {
         return multiset1.contains(element) || multiset2.contains(element);
       }
 
@@ -523,7 +535,7 @@ public int size() {
       }
 
       @Override
-      public int count(Object element) {
+      public int count(@CheckForNull Object element) {
         return multiset1.count(element) + multiset2.count(element);
       }
 
@@ -543,6 +555,7 @@ Iterator<Entry<E>> entryIterator() {
         final Iterator<? extends Entry<? extends E>> iterator2 = multiset2.entrySet().iterator();
         return new AbstractIterator<Entry<E>>() {
           @Override
+          @CheckForNull
           protected Entry<E> computeNext() {
             if (iterator1.hasNext()) {
               Entry<? extends E> entry1 = iterator1.next();
@@ -577,7 +590,7 @@ protected Entry<E> computeNext() {
    * @since 14.0
    */
   @Beta
-  public static <E> Multiset<E> difference(
+  public static <E extends @Nullable Object> Multiset<E> difference(
       final Multiset<E> multiset1, final Multiset<?> multiset2) {
     checkNotNull(multiset1);
     checkNotNull(multiset2);
@@ -585,7 +598,7 @@ public static <E> Multiset<E> difference(
     // TODO(lowasser): consider making the entries live views
     return new ViewMultiset<E>() {
       @Override
-      public int count(@NullableDecl Object element) {
+      public int count(@CheckForNull Object element) {
         int count1 = multiset1.count(element);
         return (count1 == 0) ? 0 : Math.max(0, count1 - multiset2.count(element));
       }
@@ -600,6 +613,7 @@ Iterator<E> elementIterator() {
         final Iterator<Entry<E>> iterator1 = multiset1.entrySet().iterator();
         return new AbstractIterator<E>() {
           @Override
+          @CheckForNull
           protected E computeNext() {
             while (iterator1.hasNext()) {
               Entry<E> entry1 = iterator1.next();
@@ -618,6 +632,7 @@ Iterator<Entry<E>> entryIterator() {
         final Iterator<Entry<E>> iterator1 = multiset1.entrySet().iterator();
         return new AbstractIterator<Entry<E>>() {
           @Override
+          @CheckForNull
           protected Entry<E> computeNext() {
             while (iterator1.hasNext()) {
               Entry<E> entry1 = iterator1.next();
@@ -681,7 +696,7 @@ public static boolean retainOccurrences(
   }
 
   /** Delegate implementation which cares about the element type. */
-  private static <E> boolean retainOccurrencesImpl(
+  private static <E extends @Nullable Object> boolean retainOccurrencesImpl(
       Multiset<E> multisetToModify, Multiset<?> occurrencesToRetain) {
     checkNotNull(multisetToModify);
     checkNotNull(occurrencesToRetain);
@@ -789,13 +804,13 @@ public static boolean removeOccurrences(
    * Implementation of the {@code equals}, {@code hashCode}, and {@code toString} methods of {@link
    * Multiset.Entry}.
    */
-  abstract static class AbstractEntry<E> implements Multiset.Entry<E> {
+  abstract static class AbstractEntry<E extends @Nullable Object> implements Multiset.Entry<E> {
     /**
      * Indicates whether an object equals this entry, following the behavior specified in {@link
      * Multiset.Entry#equals}.
      */
     @Override
-    public boolean equals(@NullableDecl Object object) {
+    public boolean equals(@CheckForNull Object object) {
       if (object instanceof Multiset.Entry) {
         Multiset.Entry<?> that = (Multiset.Entry<?>) object;
         return this.getCount() == that.getCount()
@@ -829,7 +844,7 @@ public String toString() {
   }
 
   /** An implementation of {@link Multiset#equals}. */
-  static boolean equalsImpl(Multiset<?> multiset, @NullableDecl Object object) {
+  static boolean equalsImpl(Multiset<?> multiset, @CheckForNull Object object) {
     if (object == multiset) {
       return true;
     }
@@ -855,7 +870,8 @@ static boolean equalsImpl(Multiset<?> multiset, @NullableDecl Object object) {
   }
 
   /** An implementation of {@link Multiset#addAll}. */
-  static <E> boolean addAllImpl(Multiset<E> self, Collection<? extends E> elements) {
+  static <E extends @Nullable Object> boolean addAllImpl(
+      Multiset<E> self, Collection<? extends E> elements) {
     checkNotNull(self);
     checkNotNull(elements);
     if (elements instanceof Multiset) {
@@ -868,7 +884,8 @@ static <E> boolean addAllImpl(Multiset<E> self, Collection<? extends E> elements
   }
 
   /** A specialization of {@code addAllImpl} for when {@code elements} is itself a Multiset. */
-  private static <E> boolean addAllImpl(Multiset<E> self, Multiset<? extends E> elements) {
+  private static <E extends @Nullable Object> boolean addAllImpl(
+      Multiset<E> self, Multiset<? extends E> elements) {
     // It'd be nice if we could specialize for ImmutableMultiset here without also retaining
     // its code when it's not in scope...
     if (elements instanceof AbstractMapBasedMultiset) {
@@ -887,7 +904,7 @@ private static <E> boolean addAllImpl(Multiset<E> self, Multiset<? extends E> el
    * A specialization of {@code addAllImpl} for when {@code elements} is an
    * AbstractMapBasedMultiset.
    */
-  private static <E> boolean addAllImpl(
+  private static <E extends @Nullable Object> boolean addAllImpl(
       Multiset<E> self, AbstractMapBasedMultiset<? extends E> elements) {
     if (elements.isEmpty()) {
       return false;
@@ -918,7 +935,8 @@ static boolean retainAllImpl(Multiset<?> self, Collection<?> elementsToRetain) {
   }
 
   /** An implementation of {@link Multiset#setCount(Object, int)}. */
-  static <E> int setCountImpl(Multiset<E> self, E element, int count) {
+  static <E extends @Nullable Object> int setCountImpl(
+      Multiset<E> self, @ParametricNullness E element, int count) {
     checkNonnegative(count, "count");
 
     int oldCount = self.count(element);
@@ -934,7 +952,8 @@ static <E> int setCountImpl(Multiset<E> self, E element, int count) {
   }
 
   /** An implementation of {@link Multiset#setCount(Object, int, int)}. */
-  static <E> boolean setCountImpl(Multiset<E> self, E element, int oldCount, int newCount) {
+  static <E extends @Nullable Object> boolean setCountImpl(
+      Multiset<E> self, @ParametricNullness E element, int oldCount, int newCount) {
     checkNonnegative(oldCount, "oldCount");
     checkNonnegative(newCount, "newCount");
 
@@ -946,16 +965,18 @@ static <E> boolean setCountImpl(Multiset<E> self, E element, int oldCount, int n
     }
   }
 
-  static <E> Iterator<E> elementIterator(Iterator<Entry<E>> entryIterator) {
+  static <E extends @Nullable Object> Iterator<E> elementIterator(
+      Iterator<Entry<E>> entryIterator) {
     return new TransformedIterator<Entry<E>, E>(entryIterator) {
       @Override
+      @ParametricNullness
       E transform(Entry<E> entry) {
         return entry.getElement();
       }
     };
   }
 
-  abstract static class ElementSet<E> extends Sets.ImprovedAbstractSet<E> {
+  abstract static class ElementSet<E extends @Nullable Object> extends Sets.ImprovedAbstractSet<E> {
     abstract Multiset<E> multiset();
 
     @Override
@@ -964,7 +985,7 @@ public void clear() {
     }
 
     @Override
-    public boolean contains(Object o) {
+    public boolean contains(@CheckForNull Object o) {
       return multiset().contains(o);
     }
 
@@ -982,7 +1003,7 @@ public boolean isEmpty() {
     public abstract Iterator<E> iterator();
 
     @Override
-    public boolean remove(Object o) {
+    public boolean remove(@CheckForNull Object o) {
       return multiset().remove(o, Integer.MAX_VALUE) > 0;
     }
 
@@ -992,11 +1013,12 @@ public int size() {
     }
   }
 
-  abstract static class EntrySet<E> extends Sets.ImprovedAbstractSet<Entry<E>> {
+  abstract static class EntrySet<E extends @Nullable Object>
+      extends Sets.ImprovedAbstractSet<Entry<E>> {
     abstract Multiset<E> multiset();
 
     @Override
-    public boolean contains(@NullableDecl Object o) {
+    public boolean contains(@CheckForNull Object o) {
       if (o instanceof Entry) {
         /*
          * The GWT compiler wrongly issues a warning here.
@@ -1015,15 +1037,16 @@ public boolean contains(@NullableDecl Object o) {
     // GWT compiler warning; see contains().
     @SuppressWarnings("cast")
     @Override
-    public boolean remove(Object object) {
+    public boolean remove(@CheckForNull Object object) {
       if (object instanceof Multiset.Entry) {
         Entry<?> entry = (Entry<?>) object;
         Object element = entry.getElement();
         int entryCount = entry.getCount();
         if (entryCount != 0) {
           // Safe as long as we never add a new entry, which we won't.
-          @SuppressWarnings("unchecked")
-          Multiset<Object> multiset = (Multiset<Object>) multiset();
+          // (Presumably it can still throw CCE/NPE but only if the underlying Multiset does.)
+          @SuppressWarnings({"unchecked", "nullness"})
+          Multiset<@Nullable Object> multiset = (Multiset<@Nullable Object>) multiset();
           return multiset.setCount(element, entryCount, 0);
         }
       }
@@ -1037,14 +1060,14 @@ public void clear() {
   }
 
   /** An implementation of {@link Multiset#iterator}. */
-  static <E> Iterator<E> iteratorImpl(Multiset<E> multiset) {
+  static <E extends @Nullable Object> Iterator<E> iteratorImpl(Multiset<E> multiset) {
     return new MultisetIteratorImpl<E>(multiset, multiset.entrySet().iterator());
   }
 
-  static final class MultisetIteratorImpl<E> implements Iterator<E> {
+  static final class MultisetIteratorImpl<E extends @Nullable Object> implements Iterator<E> {
     private final Multiset<E> multiset;
     private final Iterator<Entry<E>> entryIterator;
-    @NullableDecl private Entry<E> currentEntry;
+    @CheckForNull private Entry<E> currentEntry;
 
     /** Count of subsequent elements equal to current element */
     private int laterCount;
@@ -1065,6 +1088,7 @@ public boolean hasNext() {
     }
 
     @Override
+    @ParametricNullness
     public E next() {
       if (!hasNext()) {
         throw new NoSuchElementException();
@@ -1075,7 +1099,11 @@ public E next() {
       }
       laterCount--;
       canRemove = true;
-      return currentEntry.getElement();
+      /*
+       * requireNonNull is safe because laterCount starts at 0, forcing us to initialize
+       * currentEntry above. After that, we never clear it.
+       */
+      return requireNonNull(currentEntry).getElement();
     }
 
     @Override
@@ -1084,7 +1112,11 @@ public void remove() {
       if (totalCount == 1) {
         entryIterator.remove();
       } else {
-        multiset.remove(currentEntry.getElement());
+        /*
+         * requireNonNull is safe because canRemove is set to true only after we initialize
+         * currentEntry (which we never subsequently clear).
+         */
+        multiset.remove(requireNonNull(currentEntry).getElement());
       }
       totalCount--;
       canRemove = false;
@@ -1101,7 +1133,7 @@ static int linearTimeSizeImpl(Multiset<?> multiset) {
   }
 
   /** Used to avoid http://bugs.sun.com/view_bug.do?bug_id=6558557 */
-  static <T> Multiset<T> cast(Iterable<T> iterable) {
+  static <T extends @Nullable Object> Multiset<T> cast(Iterable<T> iterable) {
     return (Multiset<T>) iterable;
   }
 
@@ -1131,7 +1163,8 @@ public int compare(Entry<?> entry1, Entry<?> entry2) {
    * An {@link AbstractMultiset} with additional default implementations, some of them linear-time
    * implementations in terms of {@code elementSet} and {@code entrySet}.
    */
-  private abstract static class ViewMultiset<E> extends AbstractMultiset<E> {
+  private abstract static class ViewMultiset<E extends @Nullable Object>
+      extends AbstractMultiset<E> {
     @Override
     public int size() {
       return linearTimeSizeImpl(this);
diff --git a/android/guava/src/com/google/common/collect/MutableClassToInstanceMap.java b/android/guava/src/com/google/common/collect/MutableClassToInstanceMap.java
index 1f228a8f61b1..2fcf0d664e3d 100644
--- a/android/guava/src/com/google/common/collect/MutableClassToInstanceMap.java
+++ b/android/guava/src/com/google/common/collect/MutableClassToInstanceMap.java
@@ -27,20 +27,26 @@
 import java.util.LinkedHashMap;
 import java.util.Map;
 import java.util.Set;
+import javax.annotation.CheckForNull;
+import org.checkerframework.checker.nullness.qual.Nullable;
 
 /**
  * A mutable class-to-instance map backed by an arbitrary user-provided map. See also {@link
  * ImmutableClassToInstanceMap}.
  *
  * <p>See the Guava User Guide article on <a href=
- * "https://github.com/google/guava/wiki/NewCollectionTypesExplained#classtoinstancemap"> {@code
+ * "https://github.com/google/guava/wiki/NewCollectionTypesExplained#classtoinstancemap">{@code
  * ClassToInstanceMap}</a>.
  *
+ * <p>This implementation <i>does</i> support null values, despite how it is annotated; see
+ * discussion at {@link ClassToInstanceMap}.
+ *
  * @author Kevin Bourrillion
  * @since 2.0
  */
 @GwtIncompatible
 @SuppressWarnings("serial") // using writeReplace instead of standard serialization
+@ElementTypesAreNonnullByDefault
 public final class MutableClassToInstanceMap<B> extends ForwardingMap<Class<? extends B>, B>
     implements ClassToInstanceMap<B>, Serializable {
 
@@ -108,11 +114,20 @@ Entry<Class<? extends B>, B> transform(Entry<Class<? extends B>, B> from) {
 
       @Override
       public Object[] toArray() {
-        return standardToArray();
+        /*
+         * standardToArray returns `@Nullable Object[]` rather than `Object[]` but only because it
+         * can be used with collections that may contain null. This collection is a collection of
+         * non-null Entry objects (Entry objects that might contain null values but are not
+         * themselves null), so we can treat it as a plain `Object[]`.
+         */
+        @SuppressWarnings("nullness")
+        Object[] result = standardToArray();
+        return result;
       }
 
       @Override
-      public <T> T[] toArray(T[] array) {
+      @SuppressWarnings("nullness") // b/192354773 in our checker affects toArray declarations
+      public <T extends @Nullable Object> T[] toArray(T[] array) {
         return standardToArray(array);
       }
     };
@@ -120,6 +135,7 @@ public <T> T[] toArray(T[] array) {
 
   @Override
   @CanIgnoreReturnValue
+  @CheckForNull
   public B put(Class<? extends B> key, B value) {
     return super.put(key, cast(key, value));
   }
@@ -135,17 +151,20 @@ public void putAll(Map<? extends Class<? extends B>, ? extends B> map) {
 
   @CanIgnoreReturnValue
   @Override
+  @CheckForNull
   public <T extends B> T putInstance(Class<T> type, T value) {
     return cast(type, put(type, value));
   }
 
   @Override
+  @CheckForNull
   public <T extends B> T getInstance(Class<T> type) {
     return cast(type, get(type));
   }
 
   @CanIgnoreReturnValue
-  private static <B, T extends B> T cast(Class<T> type, B value) {
+  @CheckForNull
+  private static <B, T extends B> T cast(Class<T> type, @CheckForNull B value) {
     return Primitives.wrap(type).cast(value);
   }
 
diff --git a/android/guava/src/com/google/common/collect/NaturalOrdering.java b/android/guava/src/com/google/common/collect/NaturalOrdering.java
index d9792766b67b..8cb8aef9a0da 100644
--- a/android/guava/src/com/google/common/collect/NaturalOrdering.java
+++ b/android/guava/src/com/google/common/collect/NaturalOrdering.java
@@ -20,44 +20,46 @@
 
 import com.google.common.annotations.GwtCompatible;
 import java.io.Serializable;
-import org.checkerframework.checker.nullness.compatqual.NullableDecl;
+import javax.annotation.CheckForNull;
+import org.checkerframework.checker.nullness.qual.Nullable;
 
 /** An ordering that uses the natural order of the values. */
 @GwtCompatible(serializable = true)
 @SuppressWarnings({"unchecked", "rawtypes"}) // TODO(kevinb): the right way to explain this??
-final class NaturalOrdering extends Ordering<Comparable> implements Serializable {
+@ElementTypesAreNonnullByDefault
+final class NaturalOrdering extends Ordering<Comparable<?>> implements Serializable {
   static final NaturalOrdering INSTANCE = new NaturalOrdering();
 
-  @NullableDecl private transient Ordering<Comparable> nullsFirst;
-  @NullableDecl private transient Ordering<Comparable> nullsLast;
+  @CheckForNull private transient Ordering<@Nullable Comparable<?>> nullsFirst;
+  @CheckForNull private transient Ordering<@Nullable Comparable<?>> nullsLast;
 
   @Override
-  public int compare(Comparable left, Comparable right) {
+  public int compare(Comparable<?> left, Comparable<?> right) {
     checkNotNull(left); // for GWT
     checkNotNull(right);
-    return left.compareTo(right);
+    return ((Comparable<Object>) left).compareTo(right);
   }
 
   @Override
-  public <S extends Comparable> Ordering<S> nullsFirst() {
-    Ordering<Comparable> result = nullsFirst;
+  public <S extends Comparable<?>> Ordering<@Nullable S> nullsFirst() {
+    Ordering<@Nullable Comparable<?>> result = nullsFirst;
     if (result == null) {
-      result = nullsFirst = super.nullsFirst();
+      result = nullsFirst = super.<Comparable<?>>nullsFirst();
     }
-    return (Ordering<S>) result;
+    return (Ordering<@Nullable S>) result;
   }
 
   @Override
-  public <S extends Comparable> Ordering<S> nullsLast() {
-    Ordering<Comparable> result = nullsLast;
+  public <S extends Comparable<?>> Ordering<@Nullable S> nullsLast() {
+    Ordering<@Nullable Comparable<?>> result = nullsLast;
     if (result == null) {
-      result = nullsLast = super.nullsLast();
+      result = nullsLast = super.<Comparable<?>>nullsLast();
     }
-    return (Ordering<S>) result;
+    return (Ordering<@Nullable S>) result;
   }
 
   @Override
-  public <S extends Comparable> Ordering<S> reverse() {
+  public <S extends Comparable<?>> Ordering<S> reverse() {
     return (Ordering<S>) ReverseNaturalOrdering.INSTANCE;
   }
 
diff --git a/android/guava/src/com/google/common/collect/NullnessCasts.java b/android/guava/src/com/google/common/collect/NullnessCasts.java
new file mode 100644
index 000000000000..4f894dbd3139
--- /dev/null
+++ b/android/guava/src/com/google/common/collect/NullnessCasts.java
@@ -0,0 +1,68 @@
+/*
+ * Copyright (C) 2021 The Guava Authors
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file except
+ * in compliance with the License. You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software distributed under the License
+ * is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express
+ * or implied. See the License for the specific language governing permissions and limitations under
+ * the License.
+ */
+
+package com.google.common.collect;
+
+import com.google.common.annotations.GwtCompatible;
+import javax.annotation.CheckForNull;
+import org.checkerframework.checker.nullness.qual.Nullable;
+
+/** A utility method to perform unchecked casts to suppress errors produced by nullness analyses. */
+@GwtCompatible
+@ElementTypesAreNonnullByDefault
+final class NullnessCasts {
+  /**
+   * Accepts a {@code @Nullable T} and returns a plain {@code T}, without performing any check that
+   * that conversion is safe.
+   *
+   * <p>This method is intended to help with usages of type parameters that have {@linkplain
+   * ParametricNullness parametric nullness}. If a type parameter instead ranges over only non-null
+   * types (or if the type is a non-variable type, like {@code String}), then code should almost
+   * never use this method, preferring instead to call {@code requireNonNull} so as to benefit from
+   * its runtime check.
+   *
+   * <p>An example use case for this method is in implementing an {@code Iterator<T>} whose {@code
+   * next} field is lazily initialized. The type of that field would be {@code @Nullable T}, and the
+   * code would be responsible for populating a "real" {@code T} (which might still be the value
+   * {@code null}!) before returning it to callers. Depending on how the code is structured, a
+   * nullness analysis might not understand that the field has been populated. To avoid that problem
+   * without having to add {@code @SuppressWarnings}, the code can call this method.
+   *
+   * <p>Why <i>not</i> just add {@code SuppressWarnings}? The problem is that this method is
+   * typically useful for {@code return} statements. That leaves the code with two options: Either
+   * add the suppression to the whole method (which turns off checking for a large section of code),
+   * or extract a variable, and put the suppression on that. However, a local variable typically
+   * doesn't work: Because nullness analyses typically infer the nullness of local variables,
+   * there's no way to assign a {@code @Nullable T} to a field {@code T foo;} and instruct the
+   * analysis that that means "plain {@code T}" rather than the inferred type {@code @Nullable T}.
+   * (Even if supported added {@code @NonNull}, that would not help, since the problem case
+   * addressed by this method is the case in which {@code T} has parametric nullness -- and thus its
+   * value may be legitimately {@code null}.)
+   */
+  @ParametricNullness
+  @SuppressWarnings("nullness")
+  static <T extends @Nullable Object> T uncheckedCastNullableTToT(@CheckForNull T t) {
+    return t;
+  }
+
+  /** Returns {@code null} as any type, even one that does not include {@code null}. */
+  @SuppressWarnings({"nullness", "TypeParameterUnusedInFormals", "ReturnMissingNullable"})
+  // The warnings are legitimate. Each time we use this method, we document why.
+  @ParametricNullness
+  static <T extends @Nullable Object> T unsafeNull() {
+    return null;
+  }
+
+  private NullnessCasts() {}
+}
diff --git a/android/guava/src/com/google/common/collect/NullsFirstOrdering.java b/android/guava/src/com/google/common/collect/NullsFirstOrdering.java
index 21540360eb3b..ce8be2fa3cc5 100644
--- a/android/guava/src/com/google/common/collect/NullsFirstOrdering.java
+++ b/android/guava/src/com/google/common/collect/NullsFirstOrdering.java
@@ -18,11 +18,14 @@
 
 import com.google.common.annotations.GwtCompatible;
 import java.io.Serializable;
-import org.checkerframework.checker.nullness.compatqual.NullableDecl;
+import javax.annotation.CheckForNull;
+import org.checkerframework.checker.nullness.qual.Nullable;
 
 /** An ordering that treats {@code null} as less than all other values. */
 @GwtCompatible(serializable = true)
-final class NullsFirstOrdering<T> extends Ordering<T> implements Serializable {
+@ElementTypesAreNonnullByDefault
+final class NullsFirstOrdering<T extends @Nullable Object> extends Ordering<@Nullable T>
+    implements Serializable {
   final Ordering<? super T> ordering;
 
   NullsFirstOrdering(Ordering<? super T> ordering) {
@@ -30,7 +33,7 @@ final class NullsFirstOrdering<T> extends Ordering<T> implements Serializable {
   }
 
   @Override
-  public int compare(@NullableDecl T left, @NullableDecl T right) {
+  public int compare(@CheckForNull T left, @CheckForNull T right) {
     if (left == right) {
       return 0;
     }
@@ -44,24 +47,25 @@ public int compare(@NullableDecl T left, @NullableDecl T right) {
   }
 
   @Override
-  public <S extends T> Ordering<S> reverse() {
+  @SuppressWarnings("nullness") // should be safe, but not sure if we can avoid the warning
+  public <S extends @Nullable T> Ordering<S> reverse() {
     // ordering.reverse() might be optimized, so let it do its thing
     return ordering.reverse().nullsLast();
   }
 
   @SuppressWarnings("unchecked") // still need the right way to explain this
   @Override
-  public <S extends T> Ordering<S> nullsFirst() {
-    return (Ordering<S>) this;
+  public <S extends T> Ordering<@Nullable S> nullsFirst() {
+    return (Ordering<@Nullable S>) this;
   }
 
   @Override
-  public <S extends T> Ordering<S> nullsLast() {
-    return ordering.nullsLast();
+  public <S extends T> Ordering<@Nullable S> nullsLast() {
+    return ordering.<S>nullsLast();
   }
 
   @Override
-  public boolean equals(@NullableDecl Object object) {
+  public boolean equals(@CheckForNull Object object) {
     if (object == this) {
       return true;
     }
diff --git a/android/guava/src/com/google/common/collect/NullsLastOrdering.java b/android/guava/src/com/google/common/collect/NullsLastOrdering.java
index 5dd8950c9f8a..6f8f74cdd623 100644
--- a/android/guava/src/com/google/common/collect/NullsLastOrdering.java
+++ b/android/guava/src/com/google/common/collect/NullsLastOrdering.java
@@ -18,11 +18,14 @@
 
 import com.google.common.annotations.GwtCompatible;
 import java.io.Serializable;
-import org.checkerframework.checker.nullness.compatqual.NullableDecl;
+import javax.annotation.CheckForNull;
+import org.checkerframework.checker.nullness.qual.Nullable;
 
 /** An ordering that treats {@code null} as greater than all other values. */
 @GwtCompatible(serializable = true)
-final class NullsLastOrdering<T> extends Ordering<T> implements Serializable {
+@ElementTypesAreNonnullByDefault
+final class NullsLastOrdering<T extends @Nullable Object> extends Ordering<@Nullable T>
+    implements Serializable {
   final Ordering<? super T> ordering;
 
   NullsLastOrdering(Ordering<? super T> ordering) {
@@ -30,7 +33,7 @@ final class NullsLastOrdering<T> extends Ordering<T> implements Serializable {
   }
 
   @Override
-  public int compare(@NullableDecl T left, @NullableDecl T right) {
+  public int compare(@CheckForNull T left, @CheckForNull T right) {
     if (left == right) {
       return 0;
     }
@@ -44,24 +47,25 @@ public int compare(@NullableDecl T left, @NullableDecl T right) {
   }
 
   @Override
-  public <S extends T> Ordering<S> reverse() {
+  @SuppressWarnings("nullness") // should be safe, but not sure if we can avoid the warning
+  public <S extends @Nullable T> Ordering<S> reverse() {
     // ordering.reverse() might be optimized, so let it do its thing
     return ordering.reverse().nullsFirst();
   }
 
   @Override
-  public <S extends T> Ordering<S> nullsFirst() {
-    return ordering.nullsFirst();
+  public <S extends T> Ordering<@Nullable S> nullsFirst() {
+    return ordering.<S>nullsFirst();
   }
 
   @SuppressWarnings("unchecked") // still need the right way to explain this
   @Override
-  public <S extends T> Ordering<S> nullsLast() {
-    return (Ordering<S>) this;
+  public <S extends T> Ordering<@Nullable S> nullsLast() {
+    return (Ordering<@Nullable S>) this;
   }
 
   @Override
-  public boolean equals(@NullableDecl Object object) {
+  public boolean equals(@CheckForNull Object object) {
     if (object == this) {
       return true;
     }
diff --git a/android/guava/src/com/google/common/collect/ObjectArrays.java b/android/guava/src/com/google/common/collect/ObjectArrays.java
index e09fc69a3b85..0f928e170275 100644
--- a/android/guava/src/com/google/common/collect/ObjectArrays.java
+++ b/android/guava/src/com/google/common/collect/ObjectArrays.java
@@ -24,7 +24,8 @@
 import java.lang.reflect.Array;
 import java.util.Arrays;
 import java.util.Collection;
-import org.checkerframework.checker.nullness.compatqual.NullableDecl;
+import javax.annotation.CheckForNull;
+import org.checkerframework.checker.nullness.qual.Nullable;
 
 /**
  * Static utility methods pertaining to object arrays.
@@ -33,6 +34,7 @@
  * @since 2.0
  */
 @GwtCompatible(emulated = true)
+@ElementTypesAreNonnullByDefault
 public final class ObjectArrays {
 
   private ObjectArrays() {}
@@ -55,7 +57,7 @@ public static <T> T[] newArray(Class<T> type, int length) {
    * @param reference any array of the desired type
    * @param length the length of the new array
    */
-  public static <T> T[] newArray(T[] reference, int length) {
+  public static <T extends @Nullable Object> T[] newArray(T[] reference, int length) {
     return Platform.newArray(reference, length);
   }
 
@@ -82,7 +84,7 @@ public static <T> T[] concat(T[] first, T[] second, Class<T> type) {
    * @return an array whose size is one larger than {@code array}, with {@code element} occupying
    *     the first position, and the elements of {@code array} occupying the remaining elements.
    */
-  public static <T> T[] concat(@NullableDecl T element, T[] array) {
+  public static <T extends @Nullable Object> T[] concat(@ParametricNullness T element, T[] array) {
     T[] result = newArray(array, array.length + 1);
     result[0] = element;
     System.arraycopy(array, 0, result, 1, array.length);
@@ -97,7 +99,7 @@ public static <T> T[] concat(@NullableDecl T element, T[] array) {
    * @return an array whose size is one larger than {@code array}, with the same contents as {@code
    *     array}, plus {@code element} occupying the last position.
    */
-  public static <T> T[] concat(T[] array, @NullableDecl T element) {
+  public static <T extends @Nullable Object> T[] concat(T[] array, @ParametricNullness T element) {
     T[] result = Arrays.copyOf(array, array.length + 1);
     result[array.length] = element;
     return result;
@@ -124,14 +126,15 @@ public static <T> T[] concat(T[] array, @NullableDecl T element) {
    * @throws ArrayStoreException if the runtime type of the specified array is not a supertype of
    *     the runtime type of every element in the specified collection
    */
-  static <T> T[] toArrayImpl(Collection<?> c, T[] array) {
+  static <T extends @Nullable Object> T[] toArrayImpl(Collection<?> c, T[] array) {
     int size = c.size();
     if (array.length < size) {
       array = newArray(array, size);
     }
     fillArray(c, array);
     if (array.length > size) {
-      array[size] = null;
+      @Nullable Object[] unsoundlyCovariantArray = array;
+      unsoundlyCovariantArray[size] = null;
     }
     return array;
   }
@@ -147,12 +150,14 @@ static <T> T[] toArrayImpl(Collection<?> c, T[] array) {
    * collection is set to {@code null}. This is useful in determining the length of the collection
    * <i>only</i> if the caller knows that the collection does not contain any null elements.
    */
-  static <T> T[] toArrayImpl(Object[] src, int offset, int len, T[] dst) {
+  static <T extends @Nullable Object> T[] toArrayImpl(
+      @Nullable Object[] src, int offset, int len, T[] dst) {
     checkPositionIndexes(offset, offset + len, src.length);
     if (dst.length < len) {
       dst = newArray(dst, len);
     } else if (dst.length > len) {
-      dst[len] = null;
+      @Nullable Object[] unsoundlyCovariantArray = dst;
+      unsoundlyCovariantArray[len] = null;
     }
     System.arraycopy(src, offset, dst, 0, len);
     return dst;
@@ -170,7 +175,7 @@ static <T> T[] toArrayImpl(Object[] src, int offset, int len, T[] dst) {
    *
    * @param c the collection for which to return an array of elements
    */
-  static Object[] toArrayImpl(Collection<?> c) {
+  static @Nullable Object[] toArrayImpl(Collection<?> c) {
     return fillArray(c, new Object[c.size()]);
   }
 
@@ -178,18 +183,18 @@ static Object[] toArrayImpl(Collection<?> c) {
    * Returns a copy of the specified subrange of the specified array that is literally an Object[],
    * and not e.g. a {@code String[]}.
    */
-  static Object[] copyAsObjectArray(Object[] elements, int offset, int length) {
+  static @Nullable Object[] copyAsObjectArray(@Nullable Object[] elements, int offset, int length) {
     checkPositionIndexes(offset, offset + length, elements.length);
     if (length == 0) {
       return new Object[0];
     }
-    Object[] result = new Object[length];
+    @Nullable Object[] result = new Object[length];
     System.arraycopy(elements, offset, result, 0, length);
     return result;
   }
 
   @CanIgnoreReturnValue
-  private static Object[] fillArray(Iterable<?> elements, Object[] array) {
+  private static @Nullable Object[] fillArray(Iterable<?> elements, @Nullable Object[] array) {
     int i = 0;
     for (Object element : elements) {
       array[i++] = element;
@@ -206,11 +211,12 @@ static void swap(Object[] array, int i, int j) {
 
   @CanIgnoreReturnValue
   static Object[] checkElementsNotNull(Object... array) {
-    return checkElementsNotNull(array, array.length);
+    checkElementsNotNull(array, array.length);
+    return array;
   }
 
   @CanIgnoreReturnValue
-  static Object[] checkElementsNotNull(Object[] array, int length) {
+  static @Nullable Object[] checkElementsNotNull(@Nullable Object[] array, int length) {
     for (int i = 0; i < length; i++) {
       checkElementNotNull(array[i], i);
     }
@@ -220,7 +226,7 @@ static Object[] checkElementsNotNull(Object[] array, int length) {
   // We do this instead of Preconditions.checkNotNull to save boxing and array
   // creation cost.
   @CanIgnoreReturnValue
-  static Object checkElementNotNull(Object element, int index) {
+  static Object checkElementNotNull(@CheckForNull Object element, int index) {
     if (element == null) {
       throw new NullPointerException("at index " + index);
     }
diff --git a/android/guava/src/com/google/common/collect/ObjectCountHashMap.java b/android/guava/src/com/google/common/collect/ObjectCountHashMap.java
index 8f6003f2ce1d..29d5bcde4039 100644
--- a/android/guava/src/com/google/common/collect/ObjectCountHashMap.java
+++ b/android/guava/src/com/google/common/collect/ObjectCountHashMap.java
@@ -28,21 +28,22 @@
 import com.google.common.collect.Multisets.AbstractEntry;
 import com.google.errorprone.annotations.CanIgnoreReturnValue;
 import java.util.Arrays;
-import org.checkerframework.checker.nullness.compatqual.NullableDecl;
+import javax.annotation.CheckForNull;
+import org.checkerframework.checker.nullness.qual.Nullable;
 
 /**
- * ObjectCountHashMap is an implementation of {@code AbstractObjectCountMap} that uses arrays to
- * store key objects and count values. Comparing to using a traditional {@code HashMap}
- * implementation which stores keys and count values as map entries, {@code ObjectCountHashMap}
- * minimizes object allocation and reduces memory footprint.
+ * {@code ObjectCountHashMap} uses arrays to store key objects and count values. Comparing to using
+ * a traditional {@code HashMap} implementation which stores keys and count values as map entries,
+ * {@code ObjectCountHashMap} minimizes object allocation and reduces memory footprint.
  *
  * <p>In the absence of element deletions, this will iterate over elements in insertion order.
  */
 @GwtCompatible(serializable = true, emulated = true)
-class ObjectCountHashMap<K> {
+@ElementTypesAreNonnullByDefault
+class ObjectCountHashMap<K extends @Nullable Object> {
 
   /** Creates an empty {@code ObjectCountHashMap} instance. */
-  public static <K> ObjectCountHashMap<K> create() {
+  static <K extends @Nullable Object> ObjectCountHashMap<K> create() {
     return new ObjectCountHashMap<K>();
   }
 
@@ -55,7 +56,8 @@ public static <K> ObjectCountHashMap<K> create() {
    *     expectedSize} elements without resizing
    * @throws IllegalArgumentException if {@code expectedSize} is negative
    */
-  public static <K> ObjectCountHashMap<K> createWithExpectedSize(int expectedSize) {
+  static <K extends @Nullable Object> ObjectCountHashMap<K> createWithExpectedSize(
+      int expectedSize) {
     return new ObjectCountHashMap<K>(expectedSize);
   }
 
@@ -74,8 +76,13 @@ public static <K> ObjectCountHashMap<K> createWithExpectedSize(int expectedSize)
   // used to indicate blank table entries
   static final int UNSET = -1;
 
+  /*
+   * The array fields below are not initialized directly in the constructor, but they're initialized
+   * by init(), which the constructor calls.
+   */
+
   /** The keys of the entries in the map. */
-  transient Object[] keys;
+  transient @Nullable Object[] keys;
 
   /** The values of the entries in the map. */
   transient int[] values;
@@ -140,7 +147,7 @@ void init(int expectedSize, float loadFactor) {
     this.table = newTable(buckets);
     this.loadFactor = loadFactor;
 
-    this.keys = new Object[expectedSize];
+    this.keys = new @Nullable Object[expectedSize];
     this.values = new int[expectedSize];
 
     this.entries = newEntries(expectedSize);
@@ -180,6 +187,7 @@ int size() {
   }
 
   @SuppressWarnings("unchecked")
+  @ParametricNullness
   K getKey(int index) {
     checkElementIndex(index, size);
     return (K) keys[index];
@@ -201,7 +209,7 @@ Entry<K> getEntry(int index) {
   }
 
   class MapEntry extends AbstractEntry<K> {
-    @NullableDecl final K key;
+    @ParametricNullness final K key;
 
     int lastKnownIndex;
 
@@ -212,6 +220,7 @@ class MapEntry extends AbstractEntry<K> {
     }
 
     @Override
+    @ParametricNullness
     public K getElement() {
       return key;
     }
@@ -271,10 +280,10 @@ void ensureCapacity(int minCapacity) {
   }
 
   @CanIgnoreReturnValue
-  public int put(@NullableDecl K key, int value) {
+  public int put(@ParametricNullness K key, int value) {
     checkPositive(value, "count");
     long[] entries = this.entries;
-    Object[] keys = this.keys;
+    @Nullable Object[] keys = this.keys;
     int[] values = this.values;
 
     int hash = smearedHash(key);
@@ -316,7 +325,7 @@ public int put(@NullableDecl K key, int value) {
   /**
    * Creates a fresh entry with the specified object at the specified position in the entry array.
    */
-  void insertEntry(int entryIndex, @NullableDecl K key, int value, int hash) {
+  void insertEntry(int entryIndex, @ParametricNullness K key, int value, int hash) {
     this.entries[entryIndex] = ((long) hash << 32) | (NEXT_MASK & UNSET);
     this.keys[entryIndex] = key;
     this.values[entryIndex] = value;
@@ -377,7 +386,7 @@ private void resizeTable(int newCapacity) { // newCapacity always a power of two
     this.table = newTable;
   }
 
-  int indexOf(@NullableDecl Object key) {
+  int indexOf(@CheckForNull Object key) {
     int hash = smearedHash(key);
     int next = table[hash & hashTableMask()];
     while (next != UNSET) {
@@ -390,21 +399,21 @@ int indexOf(@NullableDecl Object key) {
     return -1;
   }
 
-  public boolean containsKey(@NullableDecl Object key) {
+  public boolean containsKey(@CheckForNull Object key) {
     return indexOf(key) != -1;
   }
 
-  public int get(@NullableDecl Object key) {
+  public int get(@CheckForNull Object key) {
     int index = indexOf(key);
     return (index == -1) ? 0 : values[index];
   }
 
   @CanIgnoreReturnValue
-  public int remove(@NullableDecl Object key) {
+  public int remove(@CheckForNull Object key) {
     return remove(key, smearedHash(key));
   }
 
-  private int remove(@NullableDecl Object key, int hash) {
+  private int remove(@CheckForNull Object key, int hash) {
     int tableIndex = hash & hashTableMask();
     int next = table[tableIndex];
     if (next == UNSET) { // empty bucket
diff --git a/android/guava/src/com/google/common/collect/ObjectCountLinkedHashMap.java b/android/guava/src/com/google/common/collect/ObjectCountLinkedHashMap.java
index 5a5a4766a40d..266606a153fc 100644
--- a/android/guava/src/com/google/common/collect/ObjectCountLinkedHashMap.java
+++ b/android/guava/src/com/google/common/collect/ObjectCountLinkedHashMap.java
@@ -18,18 +18,20 @@
 import com.google.common.annotations.GwtCompatible;
 import com.google.common.annotations.VisibleForTesting;
 import java.util.Arrays;
+import org.checkerframework.checker.nullness.qual.Nullable;
 
 /**
- * ObjectCountLinkedHashMap is an implementation of {@code AbstractObjectCountMap} with insertion
+ * {@code ObjectCountLinkedHashMap} is a subclass of {@code ObjectCountHashMap} with insertion
  * iteration order, and uses arrays to store key objects and count values. Comparing to using a
  * traditional {@code LinkedHashMap} implementation which stores keys and count values as map
  * entries, {@code ObjectCountLinkedHashMap} minimizes object allocation and reduces memory
  * footprint.
  */
 @GwtCompatible(serializable = true, emulated = true)
-class ObjectCountLinkedHashMap<K> extends ObjectCountHashMap<K> {
+@ElementTypesAreNonnullByDefault
+class ObjectCountLinkedHashMap<K extends @Nullable Object> extends ObjectCountHashMap<K> {
   /** Creates an empty {@code ObjectCountLinkedHashMap} instance. */
-  public static <K> ObjectCountLinkedHashMap<K> create() {
+  static <K extends @Nullable Object> ObjectCountLinkedHashMap<K> create() {
     return new ObjectCountLinkedHashMap<K>();
   }
 
@@ -42,12 +44,18 @@ public static <K> ObjectCountLinkedHashMap<K> create() {
    *     expectedSize} elements without resizing
    * @throws IllegalArgumentException if {@code expectedSize} is negative
    */
-  public static <K> ObjectCountLinkedHashMap<K> createWithExpectedSize(int expectedSize) {
+  static <K extends @Nullable Object> ObjectCountLinkedHashMap<K> createWithExpectedSize(
+      int expectedSize) {
     return new ObjectCountLinkedHashMap<K>(expectedSize);
   }
 
   private static final int ENDPOINT = -2;
 
+  /*
+   * The links field is not initialized directly in the constructor, but it's initialized by init(),
+   * which the superconstructor calls.
+   */
+
   /**
    * Contains the link pointers corresponding with the entries, in the range of [0, size()). The
    * high 32 bits of each long is the "prev" pointer, whereas the low 32 bits is the "succ" pointer
@@ -141,7 +149,7 @@ private void setSucceeds(int pred, int succ) {
   }
 
   @Override
-  void insertEntry(int entryIndex, K key, int value, int hash) {
+  void insertEntry(int entryIndex, @ParametricNullness K key, int value, int hash) {
     super.insertEntry(entryIndex, key, value, hash);
     setSucceeds(lastEntry, entryIndex);
     setSucceeds(entryIndex, ENDPOINT);
diff --git a/android/guava/src/com/google/common/collect/Ordering.java b/android/guava/src/com/google/common/collect/Ordering.java
index 187aacf8fd67..025f95fb7053 100644
--- a/android/guava/src/com/google/common/collect/Ordering.java
+++ b/android/guava/src/com/google/common/collect/Ordering.java
@@ -38,7 +38,8 @@
 import java.util.TreeSet;
 import java.util.concurrent.ConcurrentMap;
 import java.util.concurrent.atomic.AtomicInteger;
-import org.checkerframework.checker.nullness.compatqual.NullableDecl;
+import javax.annotation.CheckForNull;
+import org.checkerframework.checker.nullness.qual.Nullable;
 
 /**
  * A comparator, with additional methods to support common operations. This is an "enriched" version
@@ -144,7 +145,8 @@
  * @since 2.0
  */
 @GwtCompatible
-public abstract class Ordering<T> implements Comparator<T> {
+@ElementTypesAreNonnullByDefault
+public abstract class Ordering<T extends @Nullable Object> implements Comparator<T> {
   // Natural order
 
   /**
@@ -178,7 +180,7 @@ public static <C extends Comparable> Ordering<C> natural() {
    *     wraps that comparator
    */
   @GwtCompatible(serializable = true)
-  public static <T> Ordering<T> from(Comparator<T> comparator) {
+  public static <T extends @Nullable Object> Ordering<T> from(Comparator<T> comparator) {
     return (comparator instanceof Ordering)
         ? (Ordering<T>) comparator
         : new ComparatorOrdering<T>(comparator);
@@ -191,7 +193,7 @@ public static <T> Ordering<T> from(Comparator<T> comparator) {
    */
   @GwtCompatible(serializable = true)
   @Deprecated
-  public static <T> Ordering<T> from(Ordering<T> ordering) {
+  public static <T extends @Nullable Object> Ordering<T> from(Ordering<T> ordering) {
     return checkNotNull(ordering);
   }
 
@@ -278,7 +280,7 @@ public static <T> Ordering<T> explicit(T leastValue, T... remainingValuesInOrder
    */
   @GwtCompatible(serializable = true)
   @SuppressWarnings("unchecked")
-  public static Ordering<Object> allEqual() {
+  public static Ordering<@Nullable Object> allEqual() {
     return AllEqualOrdering.INSTANCE;
   }
 
@@ -311,16 +313,16 @@ public static Ordering<Object> usingToString() {
    * @since 2.0
    */
   // TODO(kevinb): copy to Comparators, etc.
-  public static Ordering<Object> arbitrary() {
+  public static Ordering<@Nullable Object> arbitrary() {
     return ArbitraryOrderingHolder.ARBITRARY_ORDERING;
   }
 
   private static class ArbitraryOrderingHolder {
-    static final Ordering<Object> ARBITRARY_ORDERING = new ArbitraryOrdering();
+    static final Ordering<@Nullable Object> ARBITRARY_ORDERING = new ArbitraryOrdering();
   }
 
   @VisibleForTesting
-  static class ArbitraryOrdering extends Ordering<Object> {
+  static class ArbitraryOrdering extends Ordering<@Nullable Object> {
 
     private final AtomicInteger counter = new AtomicInteger(0);
     private final ConcurrentMap<Object, Integer> uids =
@@ -342,7 +344,7 @@ private Integer getUid(Object obj) {
     }
 
     @Override
-    public int compare(Object left, Object right) {
+    public int compare(@CheckForNull Object left, @CheckForNull Object right) {
       if (left == right) {
         return 0;
       } else if (left == null) {
@@ -414,7 +416,7 @@ public <S extends T> Ordering<S> reverse() {
   // type parameter <S> lets us avoid the extra <String> in statements like:
   // Ordering<String> o = Ordering.<String>natural().nullsFirst();
   @GwtCompatible(serializable = true)
-  public <S extends T> Ordering<S> nullsFirst() {
+  public <S extends T> Ordering<@Nullable S> nullsFirst() {
     return new NullsFirstOrdering<S>(this);
   }
 
@@ -427,7 +429,7 @@ public <S extends T> Ordering<S> nullsFirst() {
   // type parameter <S> lets us avoid the extra <String> in statements like:
   // Ordering<String> o = Ordering.<String>natural().nullsLast();
   @GwtCompatible(serializable = true)
-  public <S extends T> Ordering<S> nullsLast() {
+  public <S extends T> Ordering<@Nullable S> nullsLast() {
     return new NullsLastOrdering<S>(this);
   }
 
@@ -445,7 +447,7 @@ public <S extends T> Ordering<S> nullsLast() {
    * can omit the comparator if it is the natural order).
    */
   @GwtCompatible(serializable = true)
-  public <F> Ordering<F> onResultOf(Function<F, ? extends T> function) {
+  public <F extends @Nullable Object> Ordering<F> onResultOf(Function<F, ? extends T> function) {
     return new ByFunctionOrdering<>(function, this);
   }
 
@@ -491,7 +493,8 @@ public <U extends T> Ordering<U> compound(Comparator<? super U> secondaryCompara
    * @param comparators the comparators to try in order
    */
   @GwtCompatible(serializable = true)
-  public static <T> Ordering<T> compound(Iterable<? extends Comparator<? super T>> comparators) {
+  public static <T extends @Nullable Object> Ordering<T> compound(
+      Iterable<? extends Comparator<? super T>> comparators) {
     return new CompoundOrdering<T>(comparators);
   }
 
@@ -527,10 +530,9 @@ public <S extends T> Ordering<Iterable<S>> lexicographical() {
 
   // Regular instance methods
 
-  // Override to add @NullableDecl
   @CanIgnoreReturnValue // TODO(kak): Consider removing this
   @Override
-  public abstract int compare(@NullableDecl T left, @NullableDecl T right);
+  public abstract int compare(@ParametricNullness T left, @ParametricNullness T right);
 
   /**
    * Returns the least of the specified values according to this ordering. If there are multiple
@@ -546,6 +548,7 @@ public <S extends T> Ordering<Iterable<S>> lexicographical() {
    *     ordering.
    * @since 11.0
    */
+  @ParametricNullness
   public <E extends T> E min(Iterator<E> iterator) {
     // let this throw NoSuchElementException as necessary
     E minSoFar = iterator.next();
@@ -571,6 +574,7 @@ public <E extends T> E min(Iterator<E> iterator) {
    * @throws ClassCastException if the parameters are not <i>mutually comparable</i> under this
    *     ordering.
    */
+  @ParametricNullness
   public <E extends T> E min(Iterable<E> iterable) {
     return min(iterable.iterator());
   }
@@ -590,7 +594,8 @@ public <E extends T> E min(Iterable<E> iterable) {
    * @throws ClassCastException if the parameters are not <i>mutually comparable</i> under this
    *     ordering.
    */
-  public <E extends T> E min(@NullableDecl E a, @NullableDecl E b) {
+  @ParametricNullness
+  public <E extends T> E min(@ParametricNullness E a, @ParametricNullness E b) {
     return (compare(a, b) <= 0) ? a : b;
   }
 
@@ -608,7 +613,9 @@ public <E extends T> E min(@NullableDecl E a, @NullableDecl E b) {
    * @throws ClassCastException if the parameters are not <i>mutually comparable</i> under this
    *     ordering.
    */
-  public <E extends T> E min(@NullableDecl E a, @NullableDecl E b, @NullableDecl E c, E... rest) {
+  @ParametricNullness
+  public <E extends T> E min(
+      @ParametricNullness E a, @ParametricNullness E b, @ParametricNullness E c, E... rest) {
     E minSoFar = min(min(a, b), c);
 
     for (E r : rest) {
@@ -632,6 +639,7 @@ public <E extends T> E min(@NullableDecl E a, @NullableDecl E b, @NullableDecl E
    *     ordering.
    * @since 11.0
    */
+  @ParametricNullness
   public <E extends T> E max(Iterator<E> iterator) {
     // let this throw NoSuchElementException as necessary
     E maxSoFar = iterator.next();
@@ -657,6 +665,7 @@ public <E extends T> E max(Iterator<E> iterator) {
    * @throws ClassCastException if the parameters are not <i>mutually comparable</i> under this
    *     ordering.
    */
+  @ParametricNullness
   public <E extends T> E max(Iterable<E> iterable) {
     return max(iterable.iterator());
   }
@@ -676,7 +685,8 @@ public <E extends T> E max(Iterable<E> iterable) {
    * @throws ClassCastException if the parameters are not <i>mutually comparable</i> under this
    *     ordering.
    */
-  public <E extends T> E max(@NullableDecl E a, @NullableDecl E b) {
+  @ParametricNullness
+  public <E extends T> E max(@ParametricNullness E a, @ParametricNullness E b) {
     return (compare(a, b) >= 0) ? a : b;
   }
 
@@ -694,7 +704,9 @@ public <E extends T> E max(@NullableDecl E a, @NullableDecl E b) {
    * @throws ClassCastException if the parameters are not <i>mutually comparable</i> under this
    *     ordering.
    */
-  public <E extends T> E max(@NullableDecl E a, @NullableDecl E b, @NullableDecl E c, E... rest) {
+  @ParametricNullness
+  public <E extends T> E max(
+      @ParametricNullness E a, @ParametricNullness E b, @ParametricNullness E c, E... rest) {
     E maxSoFar = max(max(a, b), c);
 
     for (E r : rest) {
@@ -859,6 +871,7 @@ public <E extends T> List<E> sortedCopy(Iterable<E> elements) {
    * @since 3.0
    */
   // TODO(kevinb): rerun benchmarks including new options
+  @SuppressWarnings("nullness") // unsafe, but there's not much we can do about it now
   public <E extends T> ImmutableList<E> immutableSortedCopy(Iterable<E> elements) {
     return ImmutableList.sortedCopyOf(this, elements);
   }
@@ -920,7 +933,8 @@ public boolean isStrictlyOrdered(Iterable<? extends T> iterable) {
    * @deprecated Use {@link Collections#binarySearch(List, Object, Comparator)} directly.
    */
   @Deprecated
-  public int binarySearch(List<? extends T> sortedList, @NullableDecl T key) {
+  public int binarySearch(
+      List<? extends T> sortedList, @ParametricNullness T key) {
     return Collections.binarySearch(sortedList, key, this);
   }
 
diff --git a/android/guava/src/com/google/common/collect/ParametricNullness.java b/android/guava/src/com/google/common/collect/ParametricNullness.java
new file mode 100644
index 000000000000..94b1bcd3aaa2
--- /dev/null
+++ b/android/guava/src/com/google/common/collect/ParametricNullness.java
@@ -0,0 +1,52 @@
+/*
+ * Copyright (C) 2021 The Guava Authors
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package com.google.common.collect;
+
+import static java.lang.annotation.ElementType.FIELD;
+import static java.lang.annotation.ElementType.METHOD;
+import static java.lang.annotation.ElementType.PARAMETER;
+import static java.lang.annotation.RetentionPolicy.RUNTIME;
+
+import com.google.common.annotations.GwtCompatible;
+import java.lang.annotation.Retention;
+import java.lang.annotation.Target;
+
+/**
+ * Marks a "top-level" type-variable usage as the closest we can get to "non-nullable when
+ * non-nullable; nullable when nullable" (like the Android <a
+ * href="https://android.googlesource.com/platform/libcore/+/master/luni/src/main/java/libcore/util/NullFromTypeParam.java">{@code
+ * NullFromTypeParam}</a>).
+ *
+ * <p>Consumers of this annotation include:
+ *
+ * <ul>
+ *   <li>Kotlin, for which it makes the type-variable usage (a) a Kotlin platform type when the type
+ *       argument is non-nullable and (b) nullable when the type argument is nullable. We use this
+ *       to "undo" {@link ElementTypesAreNonnullByDefault}.
+ *   <li><a href="https://developers.google.com/j2objc">J2ObjC</a>
+ *   <li>{@code NullPointerTester}, at least in the Android backport (where the type-use annotations
+ *       {@code NullPointerTester} would need are not available) and in case of <a
+ *       href="https://bugs.openjdk.java.net/browse/JDK-8202469">JDK-8202469</a>
+ * </ul>
+ *
+ */
+@GwtCompatible
+@Retention(RUNTIME)
+@Target({FIELD, METHOD, PARAMETER})
+@javax.annotation.meta.TypeQualifierNickname
+@javax.annotation.Nonnull(when = javax.annotation.meta.When.UNKNOWN)
+@interface ParametricNullness {}
diff --git a/android/guava/src/com/google/common/collect/PeekingIterator.java b/android/guava/src/com/google/common/collect/PeekingIterator.java
index 5a6c60b2bec4..8524ed7514dc 100644
--- a/android/guava/src/com/google/common/collect/PeekingIterator.java
+++ b/android/guava/src/com/google/common/collect/PeekingIterator.java
@@ -21,12 +21,13 @@
 import com.google.errorprone.annotations.DoNotMock;
 import java.util.Iterator;
 import java.util.NoSuchElementException;
+import org.checkerframework.checker.nullness.qual.Nullable;
 
 /**
  * An iterator that supports a one-element lookahead while iterating.
  *
  * <p>See the Guava User Guide article on <a href=
- * "https://github.com/google/guava/wiki/CollectionHelpersExplained#peekingiterator"> {@code
+ * "https://github.com/google/guava/wiki/CollectionHelpersExplained#peekingiterator">{@code
  * PeekingIterator}</a>.
  *
  * @author Mick Killianey
@@ -34,7 +35,8 @@
  */
 @DoNotMock("Use Iterators.peekingIterator")
 @GwtCompatible
-public interface PeekingIterator<E> extends Iterator<E> {
+@ElementTypesAreNonnullByDefault
+public interface PeekingIterator<E extends @Nullable Object> extends Iterator<E> {
   /**
    * Returns the next element in the iteration, without advancing the iteration.
    *
@@ -44,6 +46,7 @@ public interface PeekingIterator<E> extends Iterator<E> {
    * @throws NoSuchElementException if the iteration has no more elements according to {@link
    *     #hasNext()}
    */
+  @ParametricNullness
   E peek();
 
   /**
@@ -54,6 +57,7 @@ public interface PeekingIterator<E> extends Iterator<E> {
    */
   @CanIgnoreReturnValue
   @Override
+  @ParametricNullness
   E next();
 
   /**
diff --git a/android/guava/src/com/google/common/collect/Platform.java b/android/guava/src/com/google/common/collect/Platform.java
index e4d1c4c5fd15..0b18e1ff396e 100644
--- a/android/guava/src/com/google/common/collect/Platform.java
+++ b/android/guava/src/com/google/common/collect/Platform.java
@@ -21,6 +21,7 @@
 import java.util.Arrays;
 import java.util.Map;
 import java.util.Set;
+import org.checkerframework.checker.nullness.qual.Nullable;
 
 /**
  * Methods factored out so that they can be emulated differently in GWT.
@@ -28,9 +29,11 @@
  * @author Hayward Chan
  */
 @GwtCompatible(emulated = true)
+@ElementTypesAreNonnullByDefault
 final class Platform {
   /** Returns the platform preferred implementation of a map based on a hash table. */
-  static <K, V> Map<K, V> newHashMapWithExpectedSize(int expectedSize) {
+  static <K extends @Nullable Object, V extends @Nullable Object>
+      Map<K, V> newHashMapWithExpectedSize(int expectedSize) {
     return CompactHashMap.createWithExpectedSize(expectedSize);
   }
 
@@ -38,12 +41,13 @@ static <K, V> Map<K, V> newHashMapWithExpectedSize(int expectedSize) {
    * Returns the platform preferred implementation of an insertion ordered map based on a hash
    * table.
    */
-  static <K, V> Map<K, V> newLinkedHashMapWithExpectedSize(int expectedSize) {
+  static <K extends @Nullable Object, V extends @Nullable Object>
+      Map<K, V> newLinkedHashMapWithExpectedSize(int expectedSize) {
     return CompactLinkedHashMap.createWithExpectedSize(expectedSize);
   }
 
   /** Returns the platform preferred implementation of a set based on a hash table. */
-  static <E> Set<E> newHashSetWithExpectedSize(int expectedSize) {
+  static <E extends @Nullable Object> Set<E> newHashSetWithExpectedSize(int expectedSize) {
     return CompactHashSet.createWithExpectedSize(expectedSize);
   }
 
@@ -51,7 +55,7 @@ static <E> Set<E> newHashSetWithExpectedSize(int expectedSize) {
    * Returns the platform preferred implementation of an insertion ordered set based on a hash
    * table.
    */
-  static <E> Set<E> newLinkedHashSetWithExpectedSize(int expectedSize) {
+  static <E extends @Nullable Object> Set<E> newLinkedHashSetWithExpectedSize(int expectedSize) {
     return CompactLinkedHashSet.createWithExpectedSize(expectedSize);
   }
 
@@ -59,7 +63,8 @@ static <E> Set<E> newLinkedHashSetWithExpectedSize(int expectedSize) {
    * Returns the platform preferred map implementation that preserves insertion order when used only
    * for insertions.
    */
-  static <K, V> Map<K, V> preservesInsertionOrderOnPutsMap() {
+  static <K extends @Nullable Object, V extends @Nullable Object>
+      Map<K, V> preservesInsertionOrderOnPutsMap() {
     return CompactHashMap.create();
   }
 
@@ -67,7 +72,7 @@ static <K, V> Map<K, V> preservesInsertionOrderOnPutsMap() {
    * Returns the platform preferred set implementation that preserves insertion order when used only
    * for insertions.
    */
-  static <E> Set<E> preservesInsertionOrderOnAddsSet() {
+  static <E extends @Nullable Object> Set<E> preservesInsertionOrderOnAddsSet() {
     return CompactHashSet.create();
   }
 
@@ -77,7 +82,13 @@ static <E> Set<E> preservesInsertionOrderOnAddsSet() {
    * @param reference any array of the desired type
    * @param length the length of the new array
    */
-  static <T> T[] newArray(T[] reference, int length) {
+  /*
+   * The new array contains nulls, even if the old array did not. If we wanted to be accurate, we
+   * would declare a return type of `@Nullable T[]`. However, we've decided not to think too hard
+   * about arrays for now, as they're a mess. (We previously discussed this in the review of
+   * ObjectArrays, which is the main caller of this method.)
+   */
+  static <T extends @Nullable Object> T[] newArray(T[] reference, int length) {
     Class<?> type = reference.getClass().getComponentType();
 
     // the cast is safe because
@@ -88,7 +99,16 @@ static <T> T[] newArray(T[] reference, int length) {
   }
 
   /** Equivalent to Arrays.copyOfRange(source, from, to, arrayOfType.getClass()). */
-  static <T> T[] copy(Object[] source, int from, int to, T[] arrayOfType) {
+  /*
+   * Arrays are a mess from a nullness perspective, and Class instances for object-array types are
+   * even worse. For now, we just suppress and move on with our lives.
+   *
+   * - https://github.com/jspecify/jspecify/issues/65
+   *
+   * - https://github.com/jspecify/jdk/commit/71d826792b8c7ef95d492c50a274deab938f2552
+   */
+  @SuppressWarnings("nullness")
+  static <T extends @Nullable Object> T[] copy(Object[] source, int from, int to, T[] arrayOfType) {
     return Arrays.copyOfRange(source, from, to, (Class<? extends T[]>) arrayOfType.getClass());
   }
 
diff --git a/android/guava/src/com/google/common/collect/Queues.java b/android/guava/src/com/google/common/collect/Queues.java
index fdeb369097ca..6a4dbd227ec0 100644
--- a/android/guava/src/com/google/common/collect/Queues.java
+++ b/android/guava/src/com/google/common/collect/Queues.java
@@ -32,6 +32,7 @@
 import java.util.concurrent.PriorityBlockingQueue;
 import java.util.concurrent.SynchronousQueue;
 import java.util.concurrent.TimeUnit;
+import org.checkerframework.checker.nullness.qual.Nullable;
 
 /**
  * Static utility methods pertaining to {@link Queue} and {@link Deque} instances. Also see this
@@ -41,6 +42,7 @@
  * @since 11.0
  */
 @GwtCompatible(emulated = true)
+@ElementTypesAreNonnullByDefault
 public final class Queues {
   private Queues() {}
 
@@ -188,7 +190,8 @@ public static <E> LinkedBlockingQueue<E> newLinkedBlockingQueue(Iterable<? exten
    * Creates an empty {@code PriorityBlockingQueue} with the ordering given by its elements' natural
    * ordering.
    *
-   * @since 11.0 (requires that {@code E} be {@code Comparable} since 15.0).
+   * @since 11.0 (but the bound of {@code E} was changed from {@code Object} to {@code Comparable}
+   *     in 15.0)
    */
   @GwtIncompatible // PriorityBlockingQueue
   public static <E extends Comparable> PriorityBlockingQueue<E> newPriorityBlockingQueue() {
@@ -201,7 +204,8 @@ public static <E extends Comparable> PriorityBlockingQueue<E> newPriorityBlockin
    * <p><b>Note:</b> If the specified iterable is a {@code SortedSet} or a {@code PriorityQueue},
    * this priority queue will be ordered according to the same ordering.
    *
-   * @since 11.0 (requires that {@code E} be {@code Comparable} since 15.0).
+   * @since 11.0 (but the bound of {@code E} was changed from {@code Object} to {@code Comparable}
+   *     in 15.0)
    */
   @GwtIncompatible // PriorityBlockingQueue
   public static <E extends Comparable> PriorityBlockingQueue<E> newPriorityBlockingQueue(
@@ -220,7 +224,8 @@ public static <E extends Comparable> PriorityBlockingQueue<E> newPriorityBlockin
    * Creates an empty {@code PriorityQueue} with the ordering given by its elements' natural
    * ordering.
    *
-   * @since 11.0 (requires that {@code E} be {@code Comparable} since 15.0).
+   * @since 11.0 (but the bound of {@code E} was changed from {@code Object} to {@code Comparable}
+   *     in 15.0)
    */
   public static <E extends Comparable> PriorityQueue<E> newPriorityQueue() {
     return new PriorityQueue<E>();
@@ -232,7 +237,8 @@ public static <E extends Comparable> PriorityQueue<E> newPriorityQueue() {
    * <p><b>Note:</b> If the specified iterable is a {@code SortedSet} or a {@code PriorityQueue},
    * this priority queue will be ordered according to the same ordering.
    *
-   * @since 11.0 (requires that {@code E} be {@code Comparable} since 15.0).
+   * @since 11.0 (but the bound of {@code E} was changed from {@code Object} to {@code Comparable}
+   *     in 15.0)
    */
   public static <E extends Comparable> PriorityQueue<E> newPriorityQueue(
       Iterable<? extends E> elements) {
@@ -385,7 +391,7 @@ public static <E> int drainUninterruptibly(
    * @return a synchronized view of the specified queue
    * @since 14.0
    */
-  public static <E> Queue<E> synchronizedQueue(Queue<E> queue) {
+  public static <E extends @Nullable Object> Queue<E> synchronizedQueue(Queue<E> queue) {
     return Synchronized.queue(queue, null);
   }
 
@@ -418,7 +424,7 @@ public static <E> Queue<E> synchronizedQueue(Queue<E> queue) {
    * @return a synchronized view of the specified deque
    * @since 15.0
    */
-  public static <E> Deque<E> synchronizedDeque(Deque<E> deque) {
+  public static <E extends @Nullable Object> Deque<E> synchronizedDeque(Deque<E> deque) {
     return Synchronized.deque(deque, null);
   }
 }
diff --git a/android/guava/src/com/google/common/collect/Range.java b/android/guava/src/com/google/common/collect/Range.java
index 5300b772ce82..2a5d464dc2a8 100644
--- a/android/guava/src/com/google/common/collect/Range.java
+++ b/android/guava/src/com/google/common/collect/Range.java
@@ -16,6 +16,7 @@
 
 package com.google.common.collect;
 
+import static com.google.common.base.Preconditions.checkArgument;
 import static com.google.common.base.Preconditions.checkNotNull;
 
 import com.google.common.annotations.GwtCompatible;
@@ -27,7 +28,7 @@
 import java.util.Iterator;
 import java.util.NoSuchElementException;
 import java.util.SortedSet;
-import org.checkerframework.checker.nullness.compatqual.NullableDecl;
+import javax.annotation.CheckForNull;
 
 /**
  * A range (or "interval") defines the <i>boundaries</i> around a contiguous span of values of some
@@ -117,6 +118,7 @@
  */
 @GwtCompatible
 @SuppressWarnings("rawtypes")
+@ElementTypesAreNonnullByDefault
 public final class Range<C extends Comparable> extends RangeGwtSerializationDependencies
     implements Predicate<C>, Serializable {
 
@@ -153,7 +155,7 @@ static <C extends Comparable<?>> Ordering<Range<C>> rangeLexOrdering() {
   }
 
   static <C extends Comparable<?>> Range<C> create(Cut<C> lowerBound, Cut<C> upperBound) {
-    return new Range<C>(lowerBound, upperBound);
+    return new Range<>(lowerBound, upperBound);
   }
 
   /**
@@ -329,7 +331,7 @@ public static <C extends Comparable<?>> Range<C> singleton(C value) {
   public static <C extends Comparable<?>> Range<C> encloseAll(Iterable<C> values) {
     checkNotNull(values);
     if (values instanceof SortedSet) {
-      SortedSet<? extends C> set = cast(values);
+      SortedSet<C> set = (SortedSet<C>) values;
       Comparator<?> comparator = set.comparator();
       if (Ordering.natural().equals(comparator) || comparator == null) {
         return closed(set.first(), set.last());
@@ -456,7 +458,7 @@ public boolean containsAll(Iterable<? extends C> values) {
 
     // this optimizes testing equality of two range-backed sets
     if (values instanceof SortedSet) {
-      SortedSet<? extends C> set = cast(values);
+      SortedSet<? extends C> set = (SortedSet<? extends C>) values;
       Comparator<?> comparator = set.comparator();
       if (Ordering.natural().equals(comparator) || comparator == null) {
         return contains(set.first()) && contains(set.last());
@@ -555,6 +557,15 @@ public Range<C> intersection(Range<C> connectedRange) {
     } else {
       Cut<C> newLower = (lowerCmp >= 0) ? lowerBound : connectedRange.lowerBound;
       Cut<C> newUpper = (upperCmp <= 0) ? upperBound : connectedRange.upperBound;
+
+      // create() would catch this, but give a confusing error message
+      checkArgument(
+          newLower.compareTo(newUpper) <= 0,
+          "intersection is undefined for disconnected ranges %s and %s",
+          this,
+          connectedRange);
+
+      // TODO(kevinb): all the precondition checks in the constructor are redundant...
       return create(newLower, newUpper);
     }
   }
@@ -663,7 +674,7 @@ public Range<C> canonical(DiscreteDomain<C> domain) {
    * {@code [3..3)}, {@code (3..3]}, {@code (4..4]} are all unequal.
    */
   @Override
-  public boolean equals(@NullableDecl Object object) {
+  public boolean equals(@CheckForNull Object object) {
     if (object instanceof Range) {
       Range<?> other = (Range<?>) object;
       return lowerBound.equals(other.lowerBound) && upperBound.equals(other.upperBound);
@@ -694,11 +705,6 @@ private static String toString(Cut<?> lowerBound, Cut<?> upperBound) {
     return sb.toString();
   }
 
-  /** Used to avoid http://bugs.sun.com/view_bug.do?bug_id=6558557 */
-  private static <T> SortedSet<T> cast(Iterable<T> iterable) {
-    return (SortedSet<T>) iterable;
-  }
-
   Object readResolve() {
     if (this.equals(ALL)) {
       return all();
diff --git a/android/guava/src/com/google/common/collect/RangeMap.java b/android/guava/src/com/google/common/collect/RangeMap.java
index e6c902e9c9b4..14adb00c18c0 100644
--- a/android/guava/src/com/google/common/collect/RangeMap.java
+++ b/android/guava/src/com/google/common/collect/RangeMap.java
@@ -23,7 +23,7 @@
 import java.util.Map;
 import java.util.Map.Entry;
 import java.util.NoSuchElementException;
-import org.checkerframework.checker.nullness.compatqual.NullableDecl;
+import javax.annotation.CheckForNull;
 
 /**
  * A mapping from disjoint nonempty ranges to non-null values. Queries look up the value associated
@@ -38,21 +38,27 @@
 @Beta
 @DoNotMock("Use ImmutableRangeMap or TreeRangeMap")
 @GwtIncompatible
+@ElementTypesAreNonnullByDefault
 public interface RangeMap<K extends Comparable, V> {
+  /*
+   * TODO(cpovirk): These docs sometimes say "map" and sometimes say "range map." Pick one, or at
+   * least decide on a policy for when to use which.
+   */
+
   /**
    * Returns the value associated with the specified key, or {@code null} if there is no such value.
    *
    * <p>Specifically, if any range in this range map contains the specified key, the value
    * associated with that range is returned.
    */
-  @NullableDecl
+  @CheckForNull
   V get(K key);
 
   /**
    * Returns the range containing this key and its associated value, if such a range is present in
    * the range map, or {@code null} otherwise.
    */
-  @NullableDecl
+  @CheckForNull
   Entry<Range<K>, V> getEntry(K key);
 
   /**
@@ -146,6 +152,7 @@ public interface RangeMap<K extends Comparable, V> {
    * <p>The returned range map will throw an {@link IllegalArgumentException} on an attempt to
    * insert a range not {@linkplain Range#encloses(Range) enclosed} by {@code range}.
    */
+  // TODO(cpovirk): Consider documenting that IAE on the various methods that can throw it.
   RangeMap<K, V> subRangeMap(Range<K> range);
 
   /**
@@ -153,7 +160,7 @@ public interface RangeMap<K extends Comparable, V> {
    * #asMapOfRanges()}.
    */
   @Override
-  boolean equals(@NullableDecl Object o);
+  boolean equals(@CheckForNull Object o);
 
   /** Returns {@code asMapOfRanges().hashCode()}. */
   @Override
diff --git a/android/guava/src/com/google/common/collect/RangeSet.java b/android/guava/src/com/google/common/collect/RangeSet.java
index 06c149cc1b59..8d61cf351aed 100644
--- a/android/guava/src/com/google/common/collect/RangeSet.java
+++ b/android/guava/src/com/google/common/collect/RangeSet.java
@@ -19,7 +19,7 @@
 import com.google.errorprone.annotations.DoNotMock;
 import java.util.NoSuchElementException;
 import java.util.Set;
-import org.checkerframework.checker.nullness.compatqual.NullableDecl;
+import javax.annotation.CheckForNull;
 
 /**
  * A set comprising zero or more {@linkplain Range#isEmpty nonempty}, {@linkplain
@@ -43,7 +43,7 @@
  * <p>For a {@link Set} whose contents are specified by a {@link Range}, see {@link ContiguousSet}.
  *
  * <p>See the Guava User Guide article on <a href=
- * "https://github.com/google/guava/wiki/NewCollectionTypesExplained#rangeset"> RangeSets</a>.
+ * "https://github.com/google/guava/wiki/NewCollectionTypesExplained#rangeset">RangeSets</a>.
  *
  * @author Kevin Bourrillion
  * @author Louis Wasserman
@@ -52,6 +52,7 @@
 @Beta
 @DoNotMock("Use ImmutableRangeSet or TreeRangeSet")
 @GwtIncompatible
+@ElementTypesAreNonnullByDefault
 public interface RangeSet<C extends Comparable> {
 
   // Query methods
@@ -63,6 +64,7 @@ public interface RangeSet<C extends Comparable> {
    * Returns the unique range from this range set that {@linkplain Range#contains contains} {@code
    * value}, or {@code null} if this range set does not contain {@code value}.
    */
+  @CheckForNull
   Range<C> rangeContaining(C value);
 
   /**
@@ -246,7 +248,7 @@ public interface RangeSet<C extends Comparable> {
    * according to {@link Range#equals(Object)}.
    */
   @Override
-  boolean equals(@NullableDecl Object obj);
+  boolean equals(@CheckForNull Object obj);
 
   /** Returns {@code asRanges().hashCode()}. */
   @Override
diff --git a/android/guava/src/com/google/common/collect/RegularContiguousSet.java b/android/guava/src/com/google/common/collect/RegularContiguousSet.java
index d9a63306a8e2..787606eb1f81 100644
--- a/android/guava/src/com/google/common/collect/RegularContiguousSet.java
+++ b/android/guava/src/com/google/common/collect/RegularContiguousSet.java
@@ -18,12 +18,13 @@
 import static com.google.common.base.Preconditions.checkElementIndex;
 import static com.google.common.base.Preconditions.checkNotNull;
 import static com.google.common.collect.BoundType.CLOSED;
+import static java.util.Objects.requireNonNull;
 
 import com.google.common.annotations.GwtCompatible;
 import com.google.common.annotations.GwtIncompatible;
 import java.io.Serializable;
 import java.util.Collection;
-import org.checkerframework.checker.nullness.compatqual.NullableDecl;
+import javax.annotation.CheckForNull;
 
 /**
  * An implementation of {@link ContiguousSet} that contains one or more elements.
@@ -32,6 +33,7 @@
  */
 @GwtCompatible(emulated = true)
 @SuppressWarnings("unchecked") // allow ungenerified Comparable types
+@ElementTypesAreNonnullByDefault
 final class RegularContiguousSet<C extends Comparable> extends ContiguousSet<C> {
   private final Range<C> range;
 
@@ -56,7 +58,7 @@ ContiguousSet<C> subSetImpl(
       C fromElement, boolean fromInclusive, C toElement, boolean toInclusive) {
     if (fromElement.compareTo(toElement) == 0 && !fromInclusive && !toInclusive) {
       // Range would reject our attempt to create (x, x).
-      return new EmptyContiguousSet<C>(domain);
+      return new EmptyContiguousSet<>(domain);
     }
     return intersectionInCurrentDomain(
         Range.range(
@@ -71,8 +73,9 @@ ContiguousSet<C> tailSetImpl(C fromElement, boolean inclusive) {
 
   @GwtIncompatible // not used by GWT emulation
   @Override
-  int indexOf(Object target) {
-    return contains(target) ? (int) domain.distance(first(), (C) target) : -1;
+  int indexOf(@CheckForNull Object target) {
+    // requireNonNull is safe because of the contains check.
+    return contains(target) ? (int) domain.distance(first(), (C) requireNonNull(target)) : -1;
   }
 
   @Override
@@ -81,6 +84,7 @@ public UnmodifiableIterator<C> iterator() {
       final C last = last();
 
       @Override
+      @CheckForNull
       protected C computeNext(C previous) {
         return equalsOrThrow(previous, last) ? null : domain.next(previous);
       }
@@ -94,13 +98,14 @@ public UnmodifiableIterator<C> descendingIterator() {
       final C first = first();
 
       @Override
+      @CheckForNull
       protected C computeNext(C previous) {
         return equalsOrThrow(previous, first) ? null : domain.previous(previous);
       }
     };
   }
 
-  private static boolean equalsOrThrow(Comparable<?> left, @NullableDecl Comparable<?> right) {
+  private static boolean equalsOrThrow(Comparable<?> left, @CheckForNull Comparable<?> right) {
     return right != null && Range.compareOrThrow(left, right) == 0;
   }
 
@@ -111,12 +116,14 @@ boolean isPartialView() {
 
   @Override
   public C first() {
-    return range.lowerBound.leastValueAbove(domain);
+    // requireNonNull is safe because we checked the range is not empty in ContiguousSet.create.
+    return requireNonNull(range.lowerBound.leastValueAbove(domain));
   }
 
   @Override
   public C last() {
-    return range.upperBound.greatestValueBelow(domain);
+    // requireNonNull is safe because we checked the range is not empty in ContiguousSet.create.
+    return requireNonNull(range.upperBound.greatestValueBelow(domain));
   }
 
   @Override
@@ -146,7 +153,7 @@ public int size() {
   }
 
   @Override
-  public boolean contains(@NullableDecl Object object) {
+  public boolean contains(@CheckForNull Object object) {
     if (object == null) {
       return false;
     }
@@ -195,7 +202,7 @@ public Range<C> range(BoundType lowerBoundType, BoundType upperBoundType) {
   }
 
   @Override
-  public boolean equals(@NullableDecl Object object) {
+  public boolean equals(@CheckForNull Object object) {
     if (object == this) {
       return true;
     } else if (object instanceof RegularContiguousSet) {
@@ -224,14 +231,14 @@ private SerializedForm(Range<C> range, DiscreteDomain<C> domain) {
     }
 
     private Object readResolve() {
-      return new RegularContiguousSet<C>(range, domain);
+      return new RegularContiguousSet<>(range, domain);
     }
   }
 
   @GwtIncompatible // serialization
   @Override
   Object writeReplace() {
-    return new SerializedForm<C>(range, domain);
+    return new SerializedForm<>(range, domain);
   }
 
   private static final long serialVersionUID = 0;
diff --git a/android/guava/src/com/google/common/collect/RegularImmutableAsList.java b/android/guava/src/com/google/common/collect/RegularImmutableAsList.java
index 01e5ddd3f00c..e344db1eab17 100644
--- a/android/guava/src/com/google/common/collect/RegularImmutableAsList.java
+++ b/android/guava/src/com/google/common/collect/RegularImmutableAsList.java
@@ -18,6 +18,8 @@
 
 import com.google.common.annotations.GwtCompatible;
 import com.google.common.annotations.GwtIncompatible;
+import javax.annotation.CheckForNull;
+import org.checkerframework.checker.nullness.qual.Nullable;
 
 /**
  * An {@link ImmutableAsList} implementation specialized for when the delegate collection is already
@@ -27,6 +29,7 @@
  */
 @GwtCompatible(emulated = true)
 @SuppressWarnings("serial") // uses writeReplace, not default serialization
+@ElementTypesAreNonnullByDefault
 class RegularImmutableAsList<E> extends ImmutableAsList<E> {
   private final ImmutableCollection<E> delegate;
   private final ImmutableList<? extends E> delegateList;
@@ -61,11 +64,13 @@ public UnmodifiableListIterator<E> listIterator(int index) {
 
   @GwtIncompatible // not present in emulated superclass
   @Override
-  int copyIntoArray(Object[] dst, int offset) {
+  int copyIntoArray(@Nullable Object[] dst, int offset) {
     return delegateList.copyIntoArray(dst, offset);
   }
 
   @Override
+  @CheckForNull
+  @Nullable
   Object[] internalArray() {
     return delegateList.internalArray();
   }
diff --git a/android/guava/src/com/google/common/collect/RegularImmutableBiMap.java b/android/guava/src/com/google/common/collect/RegularImmutableBiMap.java
index 2bdaf8b3abdd..2ee752cebab4 100644
--- a/android/guava/src/com/google/common/collect/RegularImmutableBiMap.java
+++ b/android/guava/src/com/google/common/collect/RegularImmutableBiMap.java
@@ -18,7 +18,8 @@
 
 import com.google.common.annotations.GwtCompatible;
 import com.google.common.annotations.VisibleForTesting;
-import org.checkerframework.checker.nullness.compatqual.NullableDecl;
+import javax.annotation.CheckForNull;
+import org.checkerframework.checker.nullness.qual.Nullable;
 
 /**
  * Bimap with zero or more mappings.
@@ -27,11 +28,12 @@
  */
 @GwtCompatible(serializable = true, emulated = true)
 @SuppressWarnings("serial") // uses writeReplace(), not default serialization
+@ElementTypesAreNonnullByDefault
 final class RegularImmutableBiMap<K, V> extends ImmutableBiMap<K, V> {
   static final RegularImmutableBiMap<Object, Object> EMPTY = new RegularImmutableBiMap<>();
 
-  private final transient Object keyHashTable;
-  @VisibleForTesting final transient Object[] alternatingKeysAndValues;
+  @CheckForNull private final transient Object keyHashTable;
+  @VisibleForTesting final transient @Nullable Object[] alternatingKeysAndValues;
   private final transient int keyOffset; // 0 for K-to-V, 1 for V-to-K
   private final transient int size;
   private final transient RegularImmutableBiMap<V, K> inverse;
@@ -47,23 +49,23 @@ private RegularImmutableBiMap() {
   }
 
   /** K-to-V constructor. */
-  RegularImmutableBiMap(Object[] alternatingKeysAndValues, int size) {
+  RegularImmutableBiMap(@Nullable Object[] alternatingKeysAndValues, int size) {
     this.alternatingKeysAndValues = alternatingKeysAndValues;
     this.size = size;
     this.keyOffset = 0;
     int tableSize = (size >= 2) ? ImmutableSet.chooseTableSize(size) : 0;
     this.keyHashTable =
-        RegularImmutableMap.createHashTable(alternatingKeysAndValues, size, tableSize, 0);
+        RegularImmutableMap.createHashTableOrThrow(alternatingKeysAndValues, size, tableSize, 0);
     Object valueHashTable =
-        RegularImmutableMap.createHashTable(alternatingKeysAndValues, size, tableSize, 1);
+        RegularImmutableMap.createHashTableOrThrow(alternatingKeysAndValues, size, tableSize, 1);
     this.inverse =
         new RegularImmutableBiMap<V, K>(valueHashTable, alternatingKeysAndValues, size, this);
   }
 
   /** V-to-K constructor. */
   private RegularImmutableBiMap(
-      Object valueHashTable,
-      Object[] alternatingKeysAndValues,
+      @CheckForNull Object valueHashTable,
+      @Nullable Object[] alternatingKeysAndValues,
       int size,
       RegularImmutableBiMap<V, K> inverse) {
     this.keyHashTable = valueHashTable;
@@ -85,9 +87,19 @@ public ImmutableBiMap<V, K> inverse() {
 
   @SuppressWarnings("unchecked")
   @Override
-  public V get(@NullableDecl Object key) {
-    return (V)
+  @CheckForNull
+  public V get(@CheckForNull Object key) {
+    Object result =
         RegularImmutableMap.get(keyHashTable, alternatingKeysAndValues, size, keyOffset, key);
+    /*
+     * We can't simply cast the result of `RegularImmutableMap.get` to V because of a bug in our
+     * nullness checker (resulting from https://github.com/jspecify/checker-framework/issues/8).
+     */
+    if (result == null) {
+      return null;
+    } else {
+      return (V) result;
+    }
   }
 
   @Override
diff --git a/android/guava/src/com/google/common/collect/RegularImmutableList.java b/android/guava/src/com/google/common/collect/RegularImmutableList.java
index 44cbab761950..baf1d66ed804 100644
--- a/android/guava/src/com/google/common/collect/RegularImmutableList.java
+++ b/android/guava/src/com/google/common/collect/RegularImmutableList.java
@@ -17,9 +17,11 @@
 package com.google.common.collect;
 
 import static com.google.common.base.Preconditions.checkElementIndex;
+import static java.util.Objects.requireNonNull;
 
 import com.google.common.annotations.GwtCompatible;
 import com.google.common.annotations.VisibleForTesting;
+import org.checkerframework.checker.nullness.qual.Nullable;
 
 /**
  * Implementation of {@link ImmutableList} backed by a simple array.
@@ -28,13 +30,15 @@
  */
 @GwtCompatible(serializable = true, emulated = true)
 @SuppressWarnings("serial") // uses writeReplace(), not default serialization
+@ElementTypesAreNonnullByDefault
 class RegularImmutableList<E> extends ImmutableList<E> {
   static final ImmutableList<Object> EMPTY = new RegularImmutableList<>(new Object[0], 0);
 
-  @VisibleForTesting final transient Object[] array;
+  // The first `size` elements are non-null.
+  @VisibleForTesting final transient @Nullable Object[] array;
   private final transient int size;
 
-  RegularImmutableList(Object[] array, int size) {
+  RegularImmutableList(@Nullable Object[] array, int size) {
     this.array = array;
     this.size = size;
   }
@@ -50,6 +54,7 @@ boolean isPartialView() {
   }
 
   @Override
+  @Nullable
   Object[] internalArray() {
     return array;
   }
@@ -65,7 +70,7 @@ int internalArrayEnd() {
   }
 
   @Override
-  int copyIntoArray(Object[] dst, int dstOff) {
+  int copyIntoArray(@Nullable Object[] dst, int dstOff) {
     System.arraycopy(array, 0, dst, dstOff, size);
     return dstOff + size;
   }
@@ -75,7 +80,8 @@ int copyIntoArray(Object[] dst, int dstOff) {
   @SuppressWarnings("unchecked")
   public E get(int index) {
     checkElementIndex(index, size);
-    return (E) array[index];
+    // requireNonNull is safe because we guarantee that the first `size` elements are non-null.
+    return (E) requireNonNull(array[index]);
   }
 
   // TODO(lowasser): benchmark optimizations for equals() and see if they're worthwhile
diff --git a/android/guava/src/com/google/common/collect/RegularImmutableMap.java b/android/guava/src/com/google/common/collect/RegularImmutableMap.java
index 4e1681ef0249..fc8082c7bbb2 100644
--- a/android/guava/src/com/google/common/collect/RegularImmutableMap.java
+++ b/android/guava/src/com/google/common/collect/RegularImmutableMap.java
@@ -19,13 +19,15 @@
 import static com.google.common.base.Preconditions.checkElementIndex;
 import static com.google.common.base.Preconditions.checkPositionIndex;
 import static com.google.common.collect.CollectPreconditions.checkEntryNotNull;
+import static java.util.Objects.requireNonNull;
 
 import com.google.common.annotations.GwtCompatible;
 import com.google.common.annotations.VisibleForTesting;
 import java.util.AbstractMap;
 import java.util.Arrays;
 import java.util.Map.Entry;
-import org.checkerframework.checker.nullness.compatqual.NullableDecl;
+import javax.annotation.CheckForNull;
+import org.checkerframework.checker.nullness.qual.Nullable;
 
 /**
  * A hash-based implementation of {@link ImmutableMap}.
@@ -33,6 +35,7 @@
  * @author Louis Wasserman
  */
 @GwtCompatible(serializable = true, emulated = true)
+@ElementTypesAreNonnullByDefault
 final class RegularImmutableMap<K, V> extends ImmutableMap<K, V> {
   private static final byte ABSENT = -1;
 
@@ -64,37 +67,99 @@ final class RegularImmutableMap<K, V> extends ImmutableMap<K, V> {
    * & (table.length - 1) instead of % table.length, though.
    */
 
-  private final transient Object hashTable;
-  @VisibleForTesting final transient Object[] alternatingKeysAndValues;
+  @CheckForNull private final transient Object hashTable;
+  @VisibleForTesting final transient @Nullable Object[] alternatingKeysAndValues;
   private final transient int size;
 
-  @SuppressWarnings("unchecked")
-  static <K, V> RegularImmutableMap<K, V> create(int n, Object[] alternatingKeysAndValues) {
+  /*
+   * We have some considerable complexity in these create methods because of
+   * Builder.buildKeepingLast(). The same Builder might be called with buildKeepingLast() and then
+   * buildOrThrow(), or vice versa. So in particular, if we modify alternatingKeysAndValues to
+   * eliminate duplicate keys (for buildKeepingLast()) then we have to ensure that a later call to
+   * buildOrThrow() will still throw as if the duplicates had not been eliminated. And the exception
+   * message must mention two values that were associated with the duplicate key in two different
+   * calls to Builder.put (though we don't really care *which* two values if there were more than
+   * two). These considerations lead us to have a field of type DuplicateKey in the Builder, which
+   * will remember the first duplicate key we encountered. All later calls to buildOrThrow() can
+   * mention that key with its values. Further duplicates might be added in the meantime but since
+   * builders only ever accumulate entries it will always be valid to throw from buildOrThrow() with
+   * the first duplicate.
+   */
+
+  // This entry point is for callers other than ImmutableMap.Builder.
+  static <K, V> RegularImmutableMap<K, V> create(
+      int n, @Nullable Object[] alternatingKeysAndValues) {
+    return create(n, alternatingKeysAndValues, /* builder= */ null);
+  }
+
+  // This entry point is used by the other create method but also directly by
+  // ImmutableMap.Builder, so that it can remember any DuplicateKey encountered and produce an
+  // exception for a later buildOrThrow(). If builder is null that means that a duplicate
+  // key will lead to an immediate exception. If it is not null then a duplicate key will instead be
+  // stored in the builder, which may use it to throw an exception later.
+  static <K, V> RegularImmutableMap<K, V> create(
+      int n, @Nullable Object[] alternatingKeysAndValues, @Nullable Builder<K, V> builder) {
     if (n == 0) {
-      return (RegularImmutableMap<K, V>) EMPTY;
+      @SuppressWarnings("unchecked")
+      RegularImmutableMap<K, V> empty = (RegularImmutableMap<K, V>) EMPTY;
+      return empty;
     } else if (n == 1) {
-      checkEntryNotNull(alternatingKeysAndValues[0], alternatingKeysAndValues[1]);
+      // requireNonNull is safe because the first `2*n` elements have been filled in.
+      checkEntryNotNull(
+          requireNonNull(alternatingKeysAndValues[0]), requireNonNull(alternatingKeysAndValues[1]));
       return new RegularImmutableMap<K, V>(null, alternatingKeysAndValues, 1);
     }
     checkPositionIndex(n, alternatingKeysAndValues.length >> 1);
     int tableSize = ImmutableSet.chooseTableSize(n);
-    Object hashTable = createHashTable(alternatingKeysAndValues, n, tableSize, 0);
+    // If there are no duplicate keys, hashTablePlus is the final hashTable value. If there *are*
+    // duplicate keys, hashTablePlus consists of 3 elements: [0] the hashTable; [1] the number of
+    // entries in alternatingKeysAndValues that are still valid after rewriting to remove
+    // duplicates; [2] a Builder.DuplicateKey that records the first duplicate key we encountered
+    // for possible later use in exceptions, perhaps straight away.
+    Object hashTablePlus = createHashTable(alternatingKeysAndValues, n, tableSize, 0);
+    Object hashTable;
+    if (hashTablePlus instanceof Object[]) {
+      Object[] hashTableAndSizeAndDuplicate = (Object[]) hashTablePlus;
+      Builder.DuplicateKey duplicateKey = (Builder.DuplicateKey) hashTableAndSizeAndDuplicate[2];
+      if (builder == null) {
+        throw duplicateKey.exception();
+      }
+      builder.duplicateKey = duplicateKey;
+      hashTable = hashTableAndSizeAndDuplicate[0];
+      n = (Integer) hashTableAndSizeAndDuplicate[1];
+      alternatingKeysAndValues = Arrays.copyOf(alternatingKeysAndValues, n * 2);
+    } else {
+      hashTable = hashTablePlus;
+    }
     return new RegularImmutableMap<K, V>(hashTable, alternatingKeysAndValues, n);
   }
 
   /**
    * Returns a hash table for the specified keys and values, and ensures that neither keys nor
-   * values are null.
+   * values are null. This method may update {@code alternatingKeysAndValues} if there are duplicate
+   * keys. If so, the return value will indicate how many entries are still valid, and will also
+   * include a {@link Builder.DuplicateKey} in case duplicate keys are not allowed now or will not
+   * be allowed on a later {@link Builder#buildOrThrow()} call.
+   *
+   * @param keyOffset 1 if this is the reverse direction of a BiMap, 0 otherwise.
+   * @return an {@code Object} that is a {@code byte[]}, {@code short[]}, or {@code int[]}, the
+   *     smallest possible to fit {@code tableSize}; or an {@code Object[]} where [0] is one of
+   *     these; [1] indicates how many element pairs in {@code alternatingKeysAndValues} are valid;
+   *     and [2] is a {@link Builder.DuplicateKey} for the first duplicate key encountered.
    */
-  static Object createHashTable(
-      Object[] alternatingKeysAndValues, int n, int tableSize, int keyOffset) {
+  @CheckForNull
+  private static Object createHashTable(
+      @Nullable Object[] alternatingKeysAndValues, int n, int tableSize, int keyOffset) {
     if (n == 1) {
       // for n=1 we don't create a hash table, but we need to do the checkEntryNotNull check!
+      // requireNonNull is safe because the first `2*n` elements have been filled in.
       checkEntryNotNull(
-          alternatingKeysAndValues[keyOffset], alternatingKeysAndValues[keyOffset ^ 1]);
+          requireNonNull(alternatingKeysAndValues[keyOffset]),
+          requireNonNull(alternatingKeysAndValues[keyOffset ^ 1]));
       return null;
     }
     int mask = tableSize - 1;
+    Builder.DuplicateKey duplicateKey = null;
     if (tableSize <= BYTE_MAX_SIZE) {
       /*
        * Use 8 bits per entry. The value is unsigned to allow use up to a size of 2^8.
@@ -105,23 +170,36 @@ static Object createHashTable(
       byte[] hashTable = new byte[tableSize];
       Arrays.fill(hashTable, ABSENT);
 
+      int outI = 0;
+      entries:
       for (int i = 0; i < n; i++) {
         int keyIndex = 2 * i + keyOffset;
-        Object key = alternatingKeysAndValues[keyIndex];
-        Object value = alternatingKeysAndValues[keyIndex ^ 1];
+        int outKeyIndex = 2 * outI + keyOffset;
+        // requireNonNull is safe because the first `2*n` elements have been filled in.
+        Object key = requireNonNull(alternatingKeysAndValues[keyIndex]);
+        Object value = requireNonNull(alternatingKeysAndValues[keyIndex ^ 1]);
         checkEntryNotNull(key, value);
         for (int h = Hashing.smear(key.hashCode()); ; h++) {
           h &= mask;
           int previousKeyIndex = hashTable[h] & BYTE_MASK; // unsigned read
           if (previousKeyIndex == BYTE_MASK) { // -1 signed becomes 255 unsigned
-            hashTable[h] = (byte) keyIndex;
+            hashTable[h] = (byte) outKeyIndex;
             break;
-          } else if (alternatingKeysAndValues[previousKeyIndex].equals(key)) {
-            throw duplicateKeyException(key, value, alternatingKeysAndValues, previousKeyIndex);
+          } else if (key.equals(alternatingKeysAndValues[previousKeyIndex])) {
+            duplicateKey =
+                new Builder.DuplicateKey(
+                    key, value, requireNonNull(alternatingKeysAndValues[previousKeyIndex ^ 1]));
+            alternatingKeysAndValues[previousKeyIndex ^ 1] = value;
+            continue entries;
           }
         }
+        if (outI < i) { // if outI == i don't bother writing the values back where they came from
+          alternatingKeysAndValues[outKeyIndex] = key;
+          alternatingKeysAndValues[outKeyIndex ^ 1] = value;
+        }
+        outI++;
       }
-      return hashTable;
+      return outI == n ? hashTable : new Object[] {hashTable, outI, duplicateKey};
     } else if (tableSize <= SHORT_MAX_SIZE) {
       /*
        * Use 16 bits per entry. The value is unsigned to allow use up to a size of 2^16.
@@ -132,23 +210,36 @@ static Object createHashTable(
       short[] hashTable = new short[tableSize];
       Arrays.fill(hashTable, ABSENT);
 
+      int outI = 0;
+      entries:
       for (int i = 0; i < n; i++) {
         int keyIndex = 2 * i + keyOffset;
-        Object key = alternatingKeysAndValues[keyIndex];
-        Object value = alternatingKeysAndValues[keyIndex ^ 1];
+        int outKeyIndex = 2 * outI + keyOffset;
+        // requireNonNull is safe because the first `2*n` elements have been filled in.
+        Object key = requireNonNull(alternatingKeysAndValues[keyIndex]);
+        Object value = requireNonNull(alternatingKeysAndValues[keyIndex ^ 1]);
         checkEntryNotNull(key, value);
         for (int h = Hashing.smear(key.hashCode()); ; h++) {
           h &= mask;
           int previousKeyIndex = hashTable[h] & SHORT_MASK; // unsigned read
           if (previousKeyIndex == SHORT_MASK) { // -1 signed becomes 65_535 unsigned
-            hashTable[h] = (short) keyIndex;
+            hashTable[h] = (short) outKeyIndex;
             break;
-          } else if (alternatingKeysAndValues[previousKeyIndex].equals(key)) {
-            throw duplicateKeyException(key, value, alternatingKeysAndValues, previousKeyIndex);
+          } else if (key.equals(alternatingKeysAndValues[previousKeyIndex])) {
+            duplicateKey =
+                new Builder.DuplicateKey(
+                    key, value, requireNonNull(alternatingKeysAndValues[previousKeyIndex ^ 1]));
+            alternatingKeysAndValues[previousKeyIndex ^ 1] = value;
+            continue entries;
           }
         }
+        if (outI < i) { // if outI == i don't bother writing the values back where they came from
+          alternatingKeysAndValues[outKeyIndex] = key;
+          alternatingKeysAndValues[outKeyIndex ^ 1] = value;
+        }
+        outI++;
       }
-      return hashTable;
+      return outI == n ? hashTable : new Object[] {hashTable, outI, duplicateKey};
     } else {
       /*
        * Use 32 bits per entry.
@@ -156,40 +247,53 @@ static Object createHashTable(
       int[] hashTable = new int[tableSize];
       Arrays.fill(hashTable, ABSENT);
 
+      int outI = 0;
+      entries:
       for (int i = 0; i < n; i++) {
         int keyIndex = 2 * i + keyOffset;
-        Object key = alternatingKeysAndValues[keyIndex];
-        Object value = alternatingKeysAndValues[keyIndex ^ 1];
+        int outKeyIndex = 2 * outI + keyOffset;
+        // requireNonNull is safe because the first `2*n` elements have been filled in.
+        Object key = requireNonNull(alternatingKeysAndValues[keyIndex]);
+        Object value = requireNonNull(alternatingKeysAndValues[keyIndex ^ 1]);
         checkEntryNotNull(key, value);
         for (int h = Hashing.smear(key.hashCode()); ; h++) {
           h &= mask;
           int previousKeyIndex = hashTable[h];
           if (previousKeyIndex == ABSENT) {
-            hashTable[h] = keyIndex;
+            hashTable[h] = outKeyIndex;
             break;
-          } else if (alternatingKeysAndValues[previousKeyIndex].equals(key)) {
-            throw duplicateKeyException(key, value, alternatingKeysAndValues, previousKeyIndex);
+          } else if (key.equals(alternatingKeysAndValues[previousKeyIndex])) {
+            duplicateKey =
+                new Builder.DuplicateKey(
+                    key, value, requireNonNull(alternatingKeysAndValues[previousKeyIndex ^ 1]));
+            alternatingKeysAndValues[previousKeyIndex ^ 1] = value;
+            continue entries;
           }
         }
+        if (outI < i) { // if outI == i don't bother writing the values back where they came from
+          alternatingKeysAndValues[outKeyIndex] = key;
+          alternatingKeysAndValues[outKeyIndex ^ 1] = value;
+        }
+        outI++;
       }
-      return hashTable;
+      return outI == n ? hashTable : new Object[] {hashTable, outI, duplicateKey};
     }
   }
 
-  private static IllegalArgumentException duplicateKeyException(
-      Object key, Object value, Object[] alternatingKeysAndValues, int previousKeyIndex) {
-    return new IllegalArgumentException(
-        "Multiple entries with same key: "
-            + key
-            + "="
-            + value
-            + " and "
-            + alternatingKeysAndValues[previousKeyIndex]
-            + "="
-            + alternatingKeysAndValues[previousKeyIndex ^ 1]);
+  @CheckForNull
+  static Object createHashTableOrThrow(
+      @Nullable Object[] alternatingKeysAndValues, int n, int tableSize, int keyOffset) {
+    Object hashTablePlus = createHashTable(alternatingKeysAndValues, n, tableSize, keyOffset);
+    if (hashTablePlus instanceof Object[]) {
+      Object[] hashTableAndSizeAndDuplicate = (Object[]) hashTablePlus;
+      Builder.DuplicateKey duplicateKey = (Builder.DuplicateKey) hashTableAndSizeAndDuplicate[2];
+      throw duplicateKey.exception();
+    }
+    return hashTablePlus;
   }
 
-  private RegularImmutableMap(Object hashTable, Object[] alternatingKeysAndValues, int size) {
+  private RegularImmutableMap(
+      @CheckForNull Object hashTable, @Nullable Object[] alternatingKeysAndValues, int size) {
     this.hashTable = hashTable;
     this.alternatingKeysAndValues = alternatingKeysAndValues;
     this.size = size;
@@ -202,22 +306,33 @@ public int size() {
 
   @SuppressWarnings("unchecked")
   @Override
-  @NullableDecl
-  public V get(@NullableDecl Object key) {
-    return (V) get(hashTable, alternatingKeysAndValues, size, 0, key);
+  @CheckForNull
+  public V get(@CheckForNull Object key) {
+    Object result = get(hashTable, alternatingKeysAndValues, size, 0, key);
+    /*
+     * We can't simply cast the result of `RegularImmutableMap.get` to V because of a bug in our
+     * nullness checker (resulting from https://github.com/jspecify/checker-framework/issues/8).
+     */
+    if (result == null) {
+      return null;
+    } else {
+      return (V) result;
+    }
   }
 
+  @CheckForNull
   static Object get(
-      @NullableDecl Object hashTableObject,
-      @NullableDecl Object[] alternatingKeysAndValues,
+      @CheckForNull Object hashTableObject,
+      @Nullable Object[] alternatingKeysAndValues,
       int size,
       int keyOffset,
-      @NullableDecl Object key) {
+      @CheckForNull Object key) {
     if (key == null) {
       return null;
     } else if (size == 1) {
-      return alternatingKeysAndValues[keyOffset].equals(key)
-          ? alternatingKeysAndValues[keyOffset ^ 1]
+      // requireNonNull is safe because the first 2 elements have been filled in.
+      return requireNonNull(alternatingKeysAndValues[keyOffset]).equals(key)
+          ? requireNonNull(alternatingKeysAndValues[keyOffset ^ 1])
           : null;
     } else if (hashTableObject == null) {
       return null;
@@ -230,7 +345,7 @@ static Object get(
         int keyIndex = hashTable[h] & BYTE_MASK; // unsigned read
         if (keyIndex == BYTE_MASK) { // -1 signed becomes 255 unsigned
           return null;
-        } else if (alternatingKeysAndValues[keyIndex].equals(key)) {
+        } else if (key.equals(alternatingKeysAndValues[keyIndex])) {
           return alternatingKeysAndValues[keyIndex ^ 1];
         }
       }
@@ -242,7 +357,7 @@ static Object get(
         int keyIndex = hashTable[h] & SHORT_MASK; // unsigned read
         if (keyIndex == SHORT_MASK) { // -1 signed becomes 65_535 unsigned
           return null;
-        } else if (alternatingKeysAndValues[keyIndex].equals(key)) {
+        } else if (key.equals(alternatingKeysAndValues[keyIndex])) {
           return alternatingKeysAndValues[keyIndex ^ 1];
         }
       }
@@ -254,7 +369,7 @@ static Object get(
         int keyIndex = hashTable[h];
         if (keyIndex == ABSENT) {
           return null;
-        } else if (alternatingKeysAndValues[keyIndex].equals(key)) {
+        } else if (key.equals(alternatingKeysAndValues[keyIndex])) {
           return alternatingKeysAndValues[keyIndex ^ 1];
         }
       }
@@ -268,11 +383,15 @@ ImmutableSet<Entry<K, V>> createEntrySet() {
 
   static class EntrySet<K, V> extends ImmutableSet<Entry<K, V>> {
     private final transient ImmutableMap<K, V> map;
-    private final transient Object[] alternatingKeysAndValues;
+    private final transient @Nullable Object[] alternatingKeysAndValues;
     private final transient int keyOffset;
     private final transient int size;
 
-    EntrySet(ImmutableMap<K, V> map, Object[] alternatingKeysAndValues, int keyOffset, int size) {
+    EntrySet(
+        ImmutableMap<K, V> map,
+        @Nullable Object[] alternatingKeysAndValues,
+        int keyOffset,
+        int size) {
       this.map = map;
       this.alternatingKeysAndValues = alternatingKeysAndValues;
       this.keyOffset = keyOffset;
@@ -295,10 +414,14 @@ ImmutableList<Entry<K, V>> createAsList() {
         @Override
         public Entry<K, V> get(int index) {
           checkElementIndex(index, size);
+          /*
+           * requireNonNull is safe because the first `2*(size+keyOffset)` elements have been filled
+           * in.
+           */
           @SuppressWarnings("unchecked")
-          K key = (K) alternatingKeysAndValues[2 * index + keyOffset];
+          K key = (K) requireNonNull(alternatingKeysAndValues[2 * index + keyOffset]);
           @SuppressWarnings("unchecked")
-          V value = (V) alternatingKeysAndValues[2 * index + (keyOffset ^ 1)];
+          V value = (V) requireNonNull(alternatingKeysAndValues[2 * index + (keyOffset ^ 1)]);
           return new AbstractMap.SimpleImmutableEntry<K, V>(key, value);
         }
 
@@ -315,7 +438,7 @@ public boolean isPartialView() {
     }
 
     @Override
-    public boolean contains(Object object) {
+    public boolean contains(@CheckForNull Object object) {
       if (object instanceof Entry) {
         Entry<?, ?> entry = (Entry<?, ?>) object;
         Object k = entry.getKey();
@@ -345,11 +468,11 @@ ImmutableSet<K> createKeySet() {
   }
 
   static final class KeysOrValuesAsList extends ImmutableList<Object> {
-    private final transient Object[] alternatingKeysAndValues;
+    private final transient @Nullable Object[] alternatingKeysAndValues;
     private final transient int offset;
     private final transient int size;
 
-    KeysOrValuesAsList(Object[] alternatingKeysAndValues, int offset, int size) {
+    KeysOrValuesAsList(@Nullable Object[] alternatingKeysAndValues, int offset, int size) {
       this.alternatingKeysAndValues = alternatingKeysAndValues;
       this.offset = offset;
       this.size = size;
@@ -358,7 +481,8 @@ static final class KeysOrValuesAsList extends ImmutableList<Object> {
     @Override
     public Object get(int index) {
       checkElementIndex(index, size);
-      return alternatingKeysAndValues[2 * index + offset];
+      // requireNonNull is safe because the first `2*(size+offset)` elements have been filled in.
+      return requireNonNull(alternatingKeysAndValues[2 * index + offset]);
     }
 
     @Override
@@ -397,7 +521,7 @@ public ImmutableList<K> asList() {
     }
 
     @Override
-    public boolean contains(@NullableDecl Object object) {
+    public boolean contains(@CheckForNull Object object) {
       return map.get(object) != null;
     }
 
diff --git a/android/guava/src/com/google/common/collect/RegularImmutableMultiset.java b/android/guava/src/com/google/common/collect/RegularImmutableMultiset.java
index 3beec6fcfc8a..6fbc099c8708 100644
--- a/android/guava/src/com/google/common/collect/RegularImmutableMultiset.java
+++ b/android/guava/src/com/google/common/collect/RegularImmutableMultiset.java
@@ -21,7 +21,7 @@
 import com.google.errorprone.annotations.concurrent.LazyInit;
 import com.google.j2objc.annotations.WeakOuter;
 import java.io.Serializable;
-import org.checkerframework.checker.nullness.compatqual.NullableDecl;
+import javax.annotation.CheckForNull;
 
 /**
  * Implementation of {@link ImmutableMultiset} with zero or more elements.
@@ -31,6 +31,7 @@
  */
 @GwtCompatible(emulated = true, serializable = true)
 @SuppressWarnings("serial") // uses writeReplace(), not default serialization
+@ElementTypesAreNonnullByDefault
 class RegularImmutableMultiset<E> extends ImmutableMultiset<E> {
   static final RegularImmutableMultiset<Object> EMPTY =
       new RegularImmutableMultiset<>(ObjectCountHashMap.create());
@@ -38,7 +39,7 @@ class RegularImmutableMultiset<E> extends ImmutableMultiset<E> {
   final transient ObjectCountHashMap<E> contents;
   private final transient int size;
 
-  @LazyInit private transient ImmutableSet<E> elementSet;
+  @LazyInit @CheckForNull private transient ImmutableSet<E> elementSet;
 
   RegularImmutableMultiset(ObjectCountHashMap<E> contents) {
     this.contents = contents;
@@ -55,7 +56,7 @@ boolean isPartialView() {
   }
 
   @Override
-  public int count(@NullableDecl Object element) {
+  public int count(@CheckForNull Object element) {
     return contents.get(element);
   }
 
@@ -79,7 +80,7 @@ E get(int index) {
     }
 
     @Override
-    public boolean contains(@NullableDecl Object object) {
+    public boolean contains(@CheckForNull Object object) {
       return RegularImmutableMultiset.this.contains(object);
     }
 
@@ -104,12 +105,13 @@ private static class SerializedForm implements Serializable {
     final Object[] elements;
     final int[] counts;
 
-    SerializedForm(Multiset<?> multiset) {
+    // "extends Object" works around https://github.com/typetools/checker-framework/issues/3013
+    SerializedForm(Multiset<? extends Object> multiset) {
       int distinct = multiset.entrySet().size();
       elements = new Object[distinct];
       counts = new int[distinct];
       int i = 0;
-      for (Entry<?> entry : multiset.entrySet()) {
+      for (Entry<? extends Object> entry : multiset.entrySet()) {
         elements[i] = entry.getElement();
         counts[i] = entry.getCount();
         i++;
diff --git a/android/guava/src/com/google/common/collect/RegularImmutableSet.java b/android/guava/src/com/google/common/collect/RegularImmutableSet.java
index b7202f84d2fe..2382ef62e798 100644
--- a/android/guava/src/com/google/common/collect/RegularImmutableSet.java
+++ b/android/guava/src/com/google/common/collect/RegularImmutableSet.java
@@ -18,7 +18,8 @@
 
 import com.google.common.annotations.GwtCompatible;
 import com.google.common.annotations.VisibleForTesting;
-import org.checkerframework.checker.nullness.compatqual.NullableDecl;
+import javax.annotation.CheckForNull;
+import org.checkerframework.checker.nullness.qual.Nullable;
 
 /**
  * Implementation of {@link ImmutableSet} with two or more elements.
@@ -27,30 +28,34 @@
  */
 @GwtCompatible(serializable = true, emulated = true)
 @SuppressWarnings("serial") // uses writeReplace(), not default serialization
+@ElementTypesAreNonnullByDefault
 final class RegularImmutableSet<E> extends ImmutableSet<E> {
+  private static final Object[] EMPTY_ARRAY = new Object[0];
   static final RegularImmutableSet<Object> EMPTY =
-      new RegularImmutableSet<>(new Object[0], 0, null, 0, 0);
+      new RegularImmutableSet<>(EMPTY_ARRAY, 0, EMPTY_ARRAY, 0, 0);
 
-  @VisibleForTesting final transient Object[] elements;
-  // the same elements in hashed positions (plus nulls)
-  @VisibleForTesting final transient Object[] table;
+  // The first `size` elements are non-null.
+  @VisibleForTesting final transient @Nullable Object[] elements;
+  private final transient int hashCode;
+  // the same values as `elements` in hashed positions (plus nulls)
+  @VisibleForTesting final transient @Nullable Object[] table;
   // 'and' with an int to get a valid table index.
   private final transient int mask;
-  private final transient int hashCode;
   private final transient int size;
 
-  RegularImmutableSet(Object[] elements, int hashCode, Object[] table, int mask, int size) {
+  RegularImmutableSet(
+      @Nullable Object[] elements, int hashCode, @Nullable Object[] table, int mask, int size) {
     this.elements = elements;
+    this.hashCode = hashCode;
     this.table = table;
     this.mask = mask;
-    this.hashCode = hashCode;
     this.size = size;
   }
 
   @Override
-  public boolean contains(@NullableDecl Object target) {
-    Object[] table = this.table;
-    if (target == null || table == null) {
+  public boolean contains(@CheckForNull Object target) {
+    @Nullable Object[] table = this.table;
+    if (target == null || table.length == 0) {
       return false;
     }
     for (int i = Hashing.smearedHash(target); ; i++) {
@@ -75,6 +80,7 @@ public UnmodifiableIterator<E> iterator() {
   }
 
   @Override
+  @Nullable
   Object[] internalArray() {
     return elements;
   }
@@ -90,7 +96,7 @@ int internalArrayEnd() {
   }
 
   @Override
-  int copyIntoArray(Object[] dst, int offset) {
+  int copyIntoArray(@Nullable Object[] dst, int offset) {
     System.arraycopy(elements, 0, dst, offset, size);
     return offset + size;
   }
diff --git a/android/guava/src/com/google/common/collect/RegularImmutableSortedMultiset.java b/android/guava/src/com/google/common/collect/RegularImmutableSortedMultiset.java
index c1d739fd9c2d..3b6d79c44c34 100644
--- a/android/guava/src/com/google/common/collect/RegularImmutableSortedMultiset.java
+++ b/android/guava/src/com/google/common/collect/RegularImmutableSortedMultiset.java
@@ -22,7 +22,7 @@
 import com.google.common.annotations.VisibleForTesting;
 import com.google.common.primitives.Ints;
 import java.util.Comparator;
-import org.checkerframework.checker.nullness.compatqual.NullableDecl;
+import javax.annotation.CheckForNull;
 
 /**
  * An immutable sorted multiset with one or more distinct elements.
@@ -31,6 +31,7 @@
  */
 @SuppressWarnings("serial") // uses writeReplace, not default serialization
 @GwtIncompatible
+@ElementTypesAreNonnullByDefault
 final class RegularImmutableSortedMultiset<E> extends ImmutableSortedMultiset<E> {
   private static final long[] ZERO_CUMULATIVE_COUNTS = {0};
 
@@ -67,17 +68,19 @@ Entry<E> getEntry(int index) {
   }
 
   @Override
+  @CheckForNull
   public Entry<E> firstEntry() {
     return isEmpty() ? null : getEntry(0);
   }
 
   @Override
+  @CheckForNull
   public Entry<E> lastEntry() {
     return isEmpty() ? null : getEntry(length - 1);
   }
 
   @Override
-  public int count(@NullableDecl Object element) {
+  public int count(@CheckForNull Object element) {
     int index = elementSet.indexOf(element);
     return (index >= 0) ? getCount(index) : 0;
   }
diff --git a/android/guava/src/com/google/common/collect/RegularImmutableSortedSet.java b/android/guava/src/com/google/common/collect/RegularImmutableSortedSet.java
index d70d8fb74c12..ef0fbb37857e 100644
--- a/android/guava/src/com/google/common/collect/RegularImmutableSortedSet.java
+++ b/android/guava/src/com/google/common/collect/RegularImmutableSortedSet.java
@@ -27,7 +27,8 @@
 import java.util.Iterator;
 import java.util.NoSuchElementException;
 import java.util.Set;
-import org.checkerframework.checker.nullness.compatqual.NullableDecl;
+import javax.annotation.CheckForNull;
+import org.checkerframework.checker.nullness.qual.Nullable;
 
 /**
  * An immutable sorted set with one or more elements. TODO(jlevy): Consider separate class for a
@@ -38,6 +39,7 @@
  */
 @GwtCompatible(serializable = true, emulated = true)
 @SuppressWarnings({"serial", "rawtypes"})
+@ElementTypesAreNonnullByDefault
 final class RegularImmutableSortedSet<E> extends ImmutableSortedSet<E> {
   static final RegularImmutableSortedSet<Comparable> NATURAL_EMPTY_SET =
       new RegularImmutableSortedSet<>(ImmutableList.<Comparable>of(), Ordering.natural());
@@ -50,6 +52,8 @@ final class RegularImmutableSortedSet<E> extends ImmutableSortedSet<E> {
   }
 
   @Override
+  @CheckForNull
+  @Nullable
   Object[] internalArray() {
     return elements.internalArray();
   }
@@ -81,7 +85,7 @@ public int size() {
   }
 
   @Override
-  public boolean contains(@NullableDecl Object o) {
+  public boolean contains(@CheckForNull Object o) {
     try {
       return o != null && unsafeBinarySearch(o) >= 0;
     } catch (ClassCastException e) {
@@ -151,12 +155,12 @@ boolean isPartialView() {
   }
 
   @Override
-  int copyIntoArray(Object[] dst, int offset) {
+  int copyIntoArray(@Nullable Object[] dst, int offset) {
     return elements.copyIntoArray(dst, offset);
   }
 
   @Override
-  public boolean equals(@NullableDecl Object object) {
+  public boolean equals(@CheckForNull Object object) {
     if (object == this) {
       return true;
     }
@@ -209,24 +213,28 @@ public E last() {
   }
 
   @Override
+  @CheckForNull
   public E lower(E element) {
     int index = headIndex(element, false) - 1;
     return (index == -1) ? null : elements.get(index);
   }
 
   @Override
+  @CheckForNull
   public E floor(E element) {
     int index = headIndex(element, true) - 1;
     return (index == -1) ? null : elements.get(index);
   }
 
   @Override
+  @CheckForNull
   public E ceiling(E element) {
     int index = tailIndex(element, true);
     return (index == size()) ? null : elements.get(index);
   }
 
   @Override
+  @CheckForNull
   public E higher(E element) {
     int index = tailIndex(element, false);
     return (index == size()) ? null : elements.get(index);
@@ -286,7 +294,7 @@ RegularImmutableSortedSet<E> getSubSet(int newFromIndex, int newToIndex) {
   }
 
   @Override
-  int indexOf(@NullableDecl Object target) {
+  int indexOf(@CheckForNull Object target) {
     if (target == null) {
       return -1;
     }
diff --git a/android/guava/src/com/google/common/collect/RegularImmutableTable.java b/android/guava/src/com/google/common/collect/RegularImmutableTable.java
index 6c35ee47cba3..337f123b698d 100644
--- a/android/guava/src/com/google/common/collect/RegularImmutableTable.java
+++ b/android/guava/src/com/google/common/collect/RegularImmutableTable.java
@@ -24,7 +24,7 @@
 import java.util.LinkedHashSet;
 import java.util.List;
 import java.util.Set;
-import org.checkerframework.checker.nullness.compatqual.NullableDecl;
+import javax.annotation.CheckForNull;
 
 /**
  * An implementation of {@link ImmutableTable} holding an arbitrary number of cells.
@@ -32,6 +32,7 @@
  * @author Gregory Kick
  */
 @GwtCompatible
+@ElementTypesAreNonnullByDefault
 abstract class RegularImmutableTable<R, C, V> extends ImmutableTable<R, C, V> {
   RegularImmutableTable() {}
 
@@ -55,7 +56,7 @@ Cell<R, C, V> get(int index) {
     }
 
     @Override
-    public boolean contains(@NullableDecl Object object) {
+    public boolean contains(@CheckForNull Object object) {
       if (object instanceof Cell) {
         Cell<?, ?, ?> cell = (Cell<?, ?, ?>) object;
         Object value = RegularImmutableTable.this.get(cell.getRowKey(), cell.getColumnKey());
@@ -97,8 +98,8 @@ boolean isPartialView() {
 
   static <R, C, V> RegularImmutableTable<R, C, V> forCells(
       List<Cell<R, C, V>> cells,
-      @NullableDecl final Comparator<? super R> rowComparator,
-      @NullableDecl final Comparator<? super C> columnComparator) {
+      @CheckForNull Comparator<? super R> rowComparator,
+      @CheckForNull Comparator<? super C> columnComparator) {
     checkNotNull(cells);
     if (rowComparator != null || columnComparator != null) {
       /*
@@ -109,20 +110,17 @@ static <R, C, V> RegularImmutableTable<R, C, V> forCells(
        * column, the rows in the second column, etc.
        */
       Comparator<Cell<R, C, V>> comparator =
-          new Comparator<Cell<R, C, V>>() {
-            @Override
-            public int compare(Cell<R, C, V> cell1, Cell<R, C, V> cell2) {
-              int rowCompare =
-                  (rowComparator == null)
-                      ? 0
-                      : rowComparator.compare(cell1.getRowKey(), cell2.getRowKey());
-              if (rowCompare != 0) {
-                return rowCompare;
-              }
-              return (columnComparator == null)
-                  ? 0
-                  : columnComparator.compare(cell1.getColumnKey(), cell2.getColumnKey());
+          (Cell<R, C, V> cell1, Cell<R, C, V> cell2) -> {
+            int rowCompare =
+                (rowComparator == null)
+                    ? 0
+                    : rowComparator.compare(cell1.getRowKey(), cell2.getRowKey());
+            if (rowCompare != 0) {
+              return rowCompare;
             }
+            return (columnComparator == null)
+                ? 0
+                : columnComparator.compare(cell1.getColumnKey(), cell2.getColumnKey());
           };
       Collections.sort(cells, comparator);
     }
@@ -135,8 +133,8 @@ static <R, C, V> RegularImmutableTable<R, C, V> forCells(Iterable<Cell<R, C, V>>
 
   private static <R, C, V> RegularImmutableTable<R, C, V> forCellsInternal(
       Iterable<Cell<R, C, V>> cells,
-      @NullableDecl Comparator<? super R> rowComparator,
-      @NullableDecl Comparator<? super C> columnComparator) {
+      @CheckForNull Comparator<? super R> rowComparator,
+      @CheckForNull Comparator<? super C> columnComparator) {
     Set<R> rowSpaceBuilder = new LinkedHashSet<>();
     Set<C> columnSpaceBuilder = new LinkedHashSet<>();
     ImmutableList<Cell<R, C, V>> cellList = ImmutableList.copyOf(cells);
@@ -174,7 +172,7 @@ static <R, C, V> RegularImmutableTable<R, C, V> forOrderedComponents(
    * We could have declared this method 'static' but the additional compile-time checks achieved by
    * referencing the type variables seem worthwhile.
    */
-  final void checkNoDuplicate(R rowKey, C columnKey, V existingValue, V newValue) {
+  final void checkNoDuplicate(R rowKey, C columnKey, @CheckForNull V existingValue, V newValue) {
     checkArgument(
         existingValue == null,
         "Duplicate key: (row=%s, column=%s), values: [%s, %s].",
diff --git a/android/guava/src/com/google/common/collect/ReverseNaturalOrdering.java b/android/guava/src/com/google/common/collect/ReverseNaturalOrdering.java
index 612d846a7727..f0c40cb61262 100644
--- a/android/guava/src/com/google/common/collect/ReverseNaturalOrdering.java
+++ b/android/guava/src/com/google/common/collect/ReverseNaturalOrdering.java
@@ -25,63 +25,64 @@
 /** An ordering that uses the reverse of the natural order of the values. */
 @GwtCompatible(serializable = true)
 @SuppressWarnings({"unchecked", "rawtypes"}) // TODO(kevinb): the right way to explain this??
-final class ReverseNaturalOrdering extends Ordering<Comparable> implements Serializable {
+@ElementTypesAreNonnullByDefault
+final class ReverseNaturalOrdering extends Ordering<Comparable<?>> implements Serializable {
   static final ReverseNaturalOrdering INSTANCE = new ReverseNaturalOrdering();
 
   @Override
-  public int compare(Comparable left, Comparable right) {
+  public int compare(Comparable<?> left, Comparable<?> right) {
     checkNotNull(left); // right null is caught later
     if (left == right) {
       return 0;
     }
 
-    return right.compareTo(left);
+    return ((Comparable<Object>) right).compareTo(left);
   }
 
   @Override
-  public <S extends Comparable> Ordering<S> reverse() {
+  public <S extends Comparable<?>> Ordering<S> reverse() {
     return Ordering.natural();
   }
 
   // Override the min/max methods to "hoist" delegation outside loops
 
   @Override
-  public <E extends Comparable> E min(E a, E b) {
+  public <E extends Comparable<?>> E min(E a, E b) {
     return NaturalOrdering.INSTANCE.max(a, b);
   }
 
   @Override
-  public <E extends Comparable> E min(E a, E b, E c, E... rest) {
+  public <E extends Comparable<?>> E min(E a, E b, E c, E... rest) {
     return NaturalOrdering.INSTANCE.max(a, b, c, rest);
   }
 
   @Override
-  public <E extends Comparable> E min(Iterator<E> iterator) {
+  public <E extends Comparable<?>> E min(Iterator<E> iterator) {
     return NaturalOrdering.INSTANCE.max(iterator);
   }
 
   @Override
-  public <E extends Comparable> E min(Iterable<E> iterable) {
+  public <E extends Comparable<?>> E min(Iterable<E> iterable) {
     return NaturalOrdering.INSTANCE.max(iterable);
   }
 
   @Override
-  public <E extends Comparable> E max(E a, E b) {
+  public <E extends Comparable<?>> E max(E a, E b) {
     return NaturalOrdering.INSTANCE.min(a, b);
   }
 
   @Override
-  public <E extends Comparable> E max(E a, E b, E c, E... rest) {
+  public <E extends Comparable<?>> E max(E a, E b, E c, E... rest) {
     return NaturalOrdering.INSTANCE.min(a, b, c, rest);
   }
 
   @Override
-  public <E extends Comparable> E max(Iterator<E> iterator) {
+  public <E extends Comparable<?>> E max(Iterator<E> iterator) {
     return NaturalOrdering.INSTANCE.min(iterator);
   }
 
   @Override
-  public <E extends Comparable> E max(Iterable<E> iterable) {
+  public <E extends Comparable<?>> E max(Iterable<E> iterable) {
     return NaturalOrdering.INSTANCE.min(iterable);
   }
 
diff --git a/android/guava/src/com/google/common/collect/ReverseOrdering.java b/android/guava/src/com/google/common/collect/ReverseOrdering.java
index 9f65e5976034..6c1e74dd73d5 100644
--- a/android/guava/src/com/google/common/collect/ReverseOrdering.java
+++ b/android/guava/src/com/google/common/collect/ReverseOrdering.java
@@ -21,11 +21,14 @@
 import com.google.common.annotations.GwtCompatible;
 import java.io.Serializable;
 import java.util.Iterator;
-import org.checkerframework.checker.nullness.compatqual.NullableDecl;
+import javax.annotation.CheckForNull;
+import org.checkerframework.checker.nullness.qual.Nullable;
 
 /** An ordering that uses the reverse of a given order. */
 @GwtCompatible(serializable = true)
-final class ReverseOrdering<T> extends Ordering<T> implements Serializable {
+@ElementTypesAreNonnullByDefault
+final class ReverseOrdering<T extends @Nullable Object> extends Ordering<T>
+    implements Serializable {
   final Ordering<? super T> forwardOrder;
 
   ReverseOrdering(Ordering<? super T> forwardOrder) {
@@ -33,7 +36,7 @@ final class ReverseOrdering<T> extends Ordering<T> implements Serializable {
   }
 
   @Override
-  public int compare(T a, T b) {
+  public int compare(@ParametricNullness T a, @ParametricNullness T b) {
     return forwardOrder.compare(b, a);
   }
 
@@ -46,12 +49,13 @@ public <S extends T> Ordering<S> reverse() {
   // Override the min/max methods to "hoist" delegation outside loops
 
   @Override
-  public <E extends T> E min(E a, E b) {
+  public <E extends T> E min(@ParametricNullness E a, @ParametricNullness E b) {
     return forwardOrder.max(a, b);
   }
 
   @Override
-  public <E extends T> E min(E a, E b, E c, E... rest) {
+  public <E extends T> E min(
+      @ParametricNullness E a, @ParametricNullness E b, @ParametricNullness E c, E... rest) {
     return forwardOrder.max(a, b, c, rest);
   }
 
@@ -66,12 +70,13 @@ public <E extends T> E min(Iterable<E> iterable) {
   }
 
   @Override
-  public <E extends T> E max(E a, E b) {
+  public <E extends T> E max(@ParametricNullness E a, @ParametricNullness E b) {
     return forwardOrder.min(a, b);
   }
 
   @Override
-  public <E extends T> E max(E a, E b, E c, E... rest) {
+  public <E extends T> E max(
+      @ParametricNullness E a, @ParametricNullness E b, @ParametricNullness E c, E... rest) {
     return forwardOrder.min(a, b, c, rest);
   }
 
@@ -91,7 +96,7 @@ public int hashCode() {
   }
 
   @Override
-  public boolean equals(@NullableDecl Object object) {
+  public boolean equals(@CheckForNull Object object) {
     if (object == this) {
       return true;
     }
diff --git a/android/guava/src/com/google/common/collect/RowSortedTable.java b/android/guava/src/com/google/common/collect/RowSortedTable.java
index 9cdae791946d..2c2d773f78db 100644
--- a/android/guava/src/com/google/common/collect/RowSortedTable.java
+++ b/android/guava/src/com/google/common/collect/RowSortedTable.java
@@ -21,6 +21,7 @@
 import java.util.Set;
 import java.util.SortedMap;
 import java.util.SortedSet;
+import org.checkerframework.checker.nullness.qual.Nullable;
 
 /**
  * Interface that extends {@code Table} and whose rows are sorted.
@@ -33,7 +34,10 @@
  * @since 8.0
  */
 @GwtCompatible
-public interface RowSortedTable<R, C, V> extends Table<R, C, V> {
+@ElementTypesAreNonnullByDefault
+public interface RowSortedTable<
+        R extends @Nullable Object, C extends @Nullable Object, V extends @Nullable Object>
+    extends Table<R, C, V> {
   /**
    * {@inheritDoc}
    *
diff --git a/android/guava/src/com/google/common/collect/Serialization.java b/android/guava/src/com/google/common/collect/Serialization.java
index 929a48f01c15..4ab53f2d7808 100644
--- a/android/guava/src/com/google/common/collect/Serialization.java
+++ b/android/guava/src/com/google/common/collect/Serialization.java
@@ -23,6 +23,7 @@
 import java.lang.reflect.Field;
 import java.util.Collection;
 import java.util.Map;
+import org.checkerframework.checker.nullness.qual.Nullable;
 
 /**
  * Provides static methods for serializing collection classes.
@@ -33,6 +34,7 @@
  * @author Jared Levy
  */
 @GwtIncompatible
+@ElementTypesAreNonnullByDefault
 final class Serialization {
   private Serialization() {}
 
@@ -54,7 +56,8 @@ static int readCount(ObjectInputStream stream) throws IOException {
    * <p>The serialized output consists of the number of entries, first key, first value, second key,
    * second value, and so on.
    */
-  static <K, V> void writeMap(Map<K, V> map, ObjectOutputStream stream) throws IOException {
+  static <K extends @Nullable Object, V extends @Nullable Object> void writeMap(
+      Map<K, V> map, ObjectOutputStream stream) throws IOException {
     stream.writeInt(map.size());
     for (Map.Entry<K, V> entry : map.entrySet()) {
       stream.writeObject(entry.getKey());
@@ -66,8 +69,8 @@ static <K, V> void writeMap(Map<K, V> map, ObjectOutputStream stream) throws IOE
    * Populates a map by reading an input stream, as part of deserialization. See {@link #writeMap}
    * for the data format.
    */
-  static <K, V> void populateMap(Map<K, V> map, ObjectInputStream stream)
-      throws IOException, ClassNotFoundException {
+  static <K extends @Nullable Object, V extends @Nullable Object> void populateMap(
+      Map<K, V> map, ObjectInputStream stream) throws IOException, ClassNotFoundException {
     int size = stream.readInt();
     populateMap(map, stream, size);
   }
@@ -76,7 +79,8 @@ static <K, V> void populateMap(Map<K, V> map, ObjectInputStream stream)
    * Populates a map by reading an input stream, as part of deserialization. See {@link #writeMap}
    * for the data format. The size is determined by a prior call to {@link #readCount}.
    */
-  static <K, V> void populateMap(Map<K, V> map, ObjectInputStream stream, int size)
+  static <K extends @Nullable Object, V extends @Nullable Object> void populateMap(
+      Map<K, V> map, ObjectInputStream stream, int size)
       throws IOException, ClassNotFoundException {
     for (int i = 0; i < size; i++) {
       @SuppressWarnings("unchecked") // reading data stored by writeMap
@@ -94,8 +98,8 @@ static <K, V> void populateMap(Map<K, V> map, ObjectInputStream stream, int size
    * <p>The serialized output consists of the number of distinct elements, the first element, its
    * count, the second element, its count, and so on.
    */
-  static <E> void writeMultiset(Multiset<E> multiset, ObjectOutputStream stream)
-      throws IOException {
+  static <E extends @Nullable Object> void writeMultiset(
+      Multiset<E> multiset, ObjectOutputStream stream) throws IOException {
     int entryCount = multiset.entrySet().size();
     stream.writeInt(entryCount);
     for (Multiset.Entry<E> entry : multiset.entrySet()) {
@@ -108,8 +112,8 @@ static <E> void writeMultiset(Multiset<E> multiset, ObjectOutputStream stream)
    * Populates a multiset by reading an input stream, as part of deserialization. See {@link
    * #writeMultiset} for the data format.
    */
-  static <E> void populateMultiset(Multiset<E> multiset, ObjectInputStream stream)
-      throws IOException, ClassNotFoundException {
+  static <E extends @Nullable Object> void populateMultiset(
+      Multiset<E> multiset, ObjectInputStream stream) throws IOException, ClassNotFoundException {
     int distinctElements = stream.readInt();
     populateMultiset(multiset, stream, distinctElements);
   }
@@ -119,7 +123,7 @@ static <E> void populateMultiset(Multiset<E> multiset, ObjectInputStream stream)
    * #writeMultiset} for the data format. The number of distinct elements is determined by a prior
    * call to {@link #readCount}.
    */
-  static <E> void populateMultiset(
+  static <E extends @Nullable Object> void populateMultiset(
       Multiset<E> multiset, ObjectInputStream stream, int distinctElements)
       throws IOException, ClassNotFoundException {
     for (int i = 0; i < distinctElements; i++) {
@@ -138,8 +142,8 @@ static <E> void populateMultiset(
    * <p>The serialized output consists of the number of distinct keys, and then for each distinct
    * key: the key, the number of values for that key, and the key's values.
    */
-  static <K, V> void writeMultimap(Multimap<K, V> multimap, ObjectOutputStream stream)
-      throws IOException {
+  static <K extends @Nullable Object, V extends @Nullable Object> void writeMultimap(
+      Multimap<K, V> multimap, ObjectOutputStream stream) throws IOException {
     stream.writeInt(multimap.asMap().size());
     for (Map.Entry<K, Collection<V>> entry : multimap.asMap().entrySet()) {
       stream.writeObject(entry.getKey());
@@ -154,7 +158,8 @@ static <K, V> void writeMultimap(Multimap<K, V> multimap, ObjectOutputStream str
    * Populates a multimap by reading an input stream, as part of deserialization. See {@link
    * #writeMultimap} for the data format.
    */
-  static <K, V> void populateMultimap(Multimap<K, V> multimap, ObjectInputStream stream)
+  static <K extends @Nullable Object, V extends @Nullable Object> void populateMultimap(
+      Multimap<K, V> multimap, ObjectInputStream stream)
       throws IOException, ClassNotFoundException {
     int distinctKeys = stream.readInt();
     populateMultimap(multimap, stream, distinctKeys);
@@ -165,7 +170,7 @@ static <K, V> void populateMultimap(Multimap<K, V> multimap, ObjectInputStream s
    * #writeMultimap} for the data format. The number of distinct keys is determined by a prior call
    * to {@link #readCount}.
    */
-  static <K, V> void populateMultimap(
+  static <K extends @Nullable Object, V extends @Nullable Object> void populateMultimap(
       Multimap<K, V> multimap, ObjectInputStream stream, int distinctKeys)
       throws IOException, ClassNotFoundException {
     for (int i = 0; i < distinctKeys; i++) {
@@ -182,10 +187,10 @@ static <K, V> void populateMultimap(
   }
 
   // Secret sauce for setting final fields; don't make it public.
-  static <T> FieldSetter<T> getFieldSetter(final Class<T> clazz, String fieldName) {
+  static <T> FieldSetter<T> getFieldSetter(Class<T> clazz, String fieldName) {
     try {
       Field field = clazz.getDeclaredField(fieldName);
-      return new FieldSetter<T>(field);
+      return new FieldSetter<>(field);
     } catch (NoSuchFieldException e) {
       throw new AssertionError(e); // programmer error
     }
diff --git a/android/guava/src/com/google/common/collect/SetMultimap.java b/android/guava/src/com/google/common/collect/SetMultimap.java
index f2c6b57a2ad2..b7a54570a496 100644
--- a/android/guava/src/com/google/common/collect/SetMultimap.java
+++ b/android/guava/src/com/google/common/collect/SetMultimap.java
@@ -22,7 +22,8 @@
 import java.util.Map;
 import java.util.Map.Entry;
 import java.util.Set;
-import org.checkerframework.checker.nullness.compatqual.NullableDecl;
+import javax.annotation.CheckForNull;
+import org.checkerframework.checker.nullness.qual.Nullable;
 
 /**
  * A {@code Multimap} that cannot hold duplicate key-value pairs. Adding a key-value pair that's
@@ -41,15 +42,19 @@
  * {@code equals} comparisons. Use caution if mutable objects are used as keys or values in a {@code
  * SetMultimap}.
  *
+ * <p><b>Warning:</b> Do not modify either a key <i>or a value</i> of a {@code SetMultimap} in a way
+ * that affects its {@link Object#equals} behavior. Undefined behavior and bugs will result.
+ *
  * <p>See the Guava User Guide article on <a href=
- * "https://github.com/google/guava/wiki/NewCollectionTypesExplained#multimap"> {@code
- * Multimap}</a>.
+ * "https://github.com/google/guava/wiki/NewCollectionTypesExplained#multimap">{@code Multimap}</a>.
  *
  * @author Jared Levy
  * @since 2.0
  */
 @GwtCompatible
-public interface SetMultimap<K, V> extends Multimap<K, V> {
+@ElementTypesAreNonnullByDefault
+public interface SetMultimap<K extends @Nullable Object, V extends @Nullable Object>
+    extends Multimap<K, V> {
   /**
    * {@inheritDoc}
    *
@@ -58,7 +63,7 @@ public interface SetMultimap<K, V> extends Multimap<K, V> {
    * interface.
    */
   @Override
-  Set<V> get(@NullableDecl K key);
+  Set<V> get(@ParametricNullness K key);
 
   /**
    * {@inheritDoc}
@@ -69,7 +74,7 @@ public interface SetMultimap<K, V> extends Multimap<K, V> {
    */
   @CanIgnoreReturnValue
   @Override
-  Set<V> removeAll(@NullableDecl Object key);
+  Set<V> removeAll(@CheckForNull Object key);
 
   /**
    * {@inheritDoc}
@@ -82,7 +87,7 @@ public interface SetMultimap<K, V> extends Multimap<K, V> {
    */
   @CanIgnoreReturnValue
   @Override
-  Set<V> replaceValues(K key, Iterable<? extends V> values);
+  Set<V> replaceValues(@ParametricNullness K key, Iterable<? extends V> values);
 
   /**
    * {@inheritDoc}
@@ -114,5 +119,5 @@ public interface SetMultimap<K, V> extends Multimap<K, V> {
    * empty {@code ListMultimap}.
    */
   @Override
-  boolean equals(@NullableDecl Object obj);
+  boolean equals(@CheckForNull Object obj);
 }
diff --git a/android/guava/src/com/google/common/collect/Sets.java b/android/guava/src/com/google/common/collect/Sets.java
index 3fe27ba9a8f3..9948630998dd 100644
--- a/android/guava/src/com/google/common/collect/Sets.java
+++ b/android/guava/src/com/google/common/collect/Sets.java
@@ -28,6 +28,7 @@
 import com.google.common.collect.Collections2.FilteredCollection;
 import com.google.common.math.IntMath;
 import com.google.errorprone.annotations.CanIgnoreReturnValue;
+import com.google.errorprone.annotations.DoNotCall;
 import java.io.Serializable;
 import java.util.AbstractSet;
 import java.util.Arrays;
@@ -48,14 +49,15 @@
 import java.util.TreeSet;
 import java.util.concurrent.ConcurrentHashMap;
 import java.util.concurrent.CopyOnWriteArraySet;
-import org.checkerframework.checker.nullness.compatqual.NullableDecl;
+import javax.annotation.CheckForNull;
+import org.checkerframework.checker.nullness.qual.Nullable;
 
 /**
  * Static utility methods pertaining to {@link Set} instances. Also see this class's counterparts
  * {@link Lists}, {@link Maps} and {@link Queues}.
  *
  * <p>See the Guava User Guide article on <a href=
- * "https://github.com/google/guava/wiki/CollectionUtilitiesExplained#sets"> {@code Sets}</a>.
+ * "https://github.com/google/guava/wiki/CollectionUtilitiesExplained#sets">{@code Sets}</a>.
  *
  * @author Kevin Bourrillion
  * @author Jared Levy
@@ -63,6 +65,7 @@
  * @since 2.0
  */
 @GwtCompatible(emulated = true)
+@ElementTypesAreNonnullByDefault
 public final class Sets {
   private Sets() {}
 
@@ -70,7 +73,7 @@ private Sets() {}
    * {@link AbstractSet} substitute without the potentially-quadratic {@code removeAll}
    * implementation.
    */
-  abstract static class ImprovedAbstractSet<E> extends AbstractSet<E> {
+  abstract static class ImprovedAbstractSet<E extends @Nullable Object> extends AbstractSet<E> {
     @Override
     public boolean removeAll(Collection<?> c) {
       return removeAllImpl(this, c);
@@ -156,11 +159,11 @@ public static <E extends Enum<E>> EnumSet<E> newEnumSet(
    * using a {@code LinkedHashSet} instead, at the cost of increased memory footprint, to get
    * deterministic iteration behavior.
    *
-   * <p><b>Note for Java 7 and later:</b> this method is now unnecessary and should be treated as
-   * deprecated. Instead, use the {@code HashSet} constructor directly, taking advantage of the new
-   * <a href="http://goo.gl/iz2Wi">"diamond" syntax</a>.
+   * <p><b>Note:</b> this method is now unnecessary and should be treated as deprecated. Instead,
+   * use the {@code HashSet} constructor directly, taking advantage of <a
+   * href="http://goo.gl/iz2Wi">"diamond" syntax</a>.
    */
-  public static <E> HashSet<E> newHashSet() {
+  public static <E extends @Nullable Object> HashSet<E> newHashSet() {
     return new HashSet<E>();
   }
 
@@ -177,7 +180,7 @@ public static <E> HashSet<E> newHashSet() {
    * asList}{@code (...))}, or for creating an empty set then calling {@link Collections#addAll}.
    * This method is not actually very useful and will likely be deprecated in the future.
    */
-  public static <E> HashSet<E> newHashSet(E... elements) {
+  public static <E extends @Nullable Object> HashSet<E> newHashSet(E... elements) {
     HashSet<E> set = newHashSetWithExpectedSize(elements.length);
     Collections.addAll(set, elements);
     return set;
@@ -195,13 +198,13 @@ public static <E> HashSet<E> newHashSet(E... elements) {
    * <p><b>Note:</b> if {@code E} is an {@link Enum} type, use {@link #newEnumSet(Iterable, Class)}
    * instead.
    *
-   * <p><b>Note for Java 7 and later:</b> if {@code elements} is a {@link Collection}, you don't
-   * need this method. Instead, use the {@code HashSet} constructor directly, taking advantage of
-   * the new <a href="http://goo.gl/iz2Wi">"diamond" syntax</a>.
+   * <p><b>Note:</b> if {@code elements} is a {@link Collection}, you don't need this method.
+   * Instead, use the {@code HashSet} constructor directly, taking advantage of <a
+   * href="http://goo.gl/iz2Wi">"diamond" syntax</a>.
    *
    * <p>Overall, this method is not very useful and will likely be deprecated in the future.
    */
-  public static <E> HashSet<E> newHashSet(Iterable<? extends E> elements) {
+  public static <E extends @Nullable Object> HashSet<E> newHashSet(Iterable<? extends E> elements) {
     return (elements instanceof Collection)
         ? new HashSet<E>((Collection<? extends E>) elements)
         : newHashSet(elements.iterator());
@@ -219,7 +222,7 @@ public static <E> HashSet<E> newHashSet(Iterable<? extends E> elements) {
    *
    * <p>Overall, this method is not very useful and will likely be deprecated in the future.
    */
-  public static <E> HashSet<E> newHashSet(Iterator<? extends E> elements) {
+  public static <E extends @Nullable Object> HashSet<E> newHashSet(Iterator<? extends E> elements) {
     HashSet<E> set = newHashSet();
     Iterators.addAll(set, elements);
     return set;
@@ -237,7 +240,8 @@ public static <E> HashSet<E> newHashSet(Iterator<? extends E> elements) {
    *     without resizing
    * @throws IllegalArgumentException if {@code expectedSize} is negative
    */
-  public static <E> HashSet<E> newHashSetWithExpectedSize(int expectedSize) {
+  public static <E extends @Nullable Object> HashSet<E> newHashSetWithExpectedSize(
+      int expectedSize) {
     return new HashSet<E>(Maps.capacity(expectedSize));
   }
 
@@ -281,13 +285,13 @@ public static <E> Set<E> newConcurrentHashSet(Iterable<? extends E> elements) {
    *
    * <p><b>Note:</b> if mutability is not required, use {@link ImmutableSet#of()} instead.
    *
-   * <p><b>Note for Java 7 and later:</b> this method is now unnecessary and should be treated as
-   * deprecated. Instead, use the {@code LinkedHashSet} constructor directly, taking advantage of
-   * the new <a href="http://goo.gl/iz2Wi">"diamond" syntax</a>.
+   * <p><b>Note:</b> this method is now unnecessary and should be treated as deprecated. Instead,
+   * use the {@code LinkedHashSet} constructor directly, taking advantage of <a
+   * href="http://goo.gl/iz2Wi">"diamond" syntax</a>.
    *
    * @return a new, empty {@code LinkedHashSet}
    */
-  public static <E> LinkedHashSet<E> newLinkedHashSet() {
+  public static <E extends @Nullable Object> LinkedHashSet<E> newLinkedHashSet() {
     return new LinkedHashSet<E>();
   }
 
@@ -297,16 +301,17 @@ public static <E> LinkedHashSet<E> newLinkedHashSet() {
    * <p><b>Note:</b> if mutability is not required and the elements are non-null, use {@link
    * ImmutableSet#copyOf(Iterable)} instead.
    *
-   * <p><b>Note for Java 7 and later:</b> if {@code elements} is a {@link Collection}, you don't
-   * need this method. Instead, use the {@code LinkedHashSet} constructor directly, taking advantage
-   * of the new <a href="http://goo.gl/iz2Wi">"diamond" syntax</a>.
+   * <p><b>Note:</b> if {@code elements} is a {@link Collection}, you don't need this method.
+   * Instead, use the {@code LinkedHashSet} constructor directly, taking advantage of <a
+   * href="http://goo.gl/iz2Wi">"diamond" syntax</a>.
    *
    * <p>Overall, this method is not very useful and will likely be deprecated in the future.
    *
    * @param elements the elements that the set should contain, in order
    * @return a new {@code LinkedHashSet} containing those elements (minus duplicates)
    */
-  public static <E> LinkedHashSet<E> newLinkedHashSet(Iterable<? extends E> elements) {
+  public static <E extends @Nullable Object> LinkedHashSet<E> newLinkedHashSet(
+      Iterable<? extends E> elements) {
     if (elements instanceof Collection) {
       return new LinkedHashSet<E>((Collection<? extends E>) elements);
     }
@@ -327,7 +332,8 @@ public static <E> LinkedHashSet<E> newLinkedHashSet(Iterable<? extends E> elemen
    * @throws IllegalArgumentException if {@code expectedSize} is negative
    * @since 11.0
    */
-  public static <E> LinkedHashSet<E> newLinkedHashSetWithExpectedSize(int expectedSize) {
+  public static <E extends @Nullable Object> LinkedHashSet<E> newLinkedHashSetWithExpectedSize(
+      int expectedSize) {
     return new LinkedHashSet<E>(Maps.capacity(expectedSize));
   }
 
@@ -339,9 +345,9 @@ public static <E> LinkedHashSet<E> newLinkedHashSetWithExpectedSize(int expected
    *
    * <p><b>Note:</b> if mutability is not required, use {@link ImmutableSortedSet#of()} instead.
    *
-   * <p><b>Note for Java 7 and later:</b> this method is now unnecessary and should be treated as
-   * deprecated. Instead, use the {@code TreeSet} constructor directly, taking advantage of the new
-   * <a href="http://goo.gl/iz2Wi">"diamond" syntax</a>.
+   * <p><b>Note:</b> this method is now unnecessary and should be treated as deprecated. Instead,
+   * use the {@code TreeSet} constructor directly, taking advantage of <a
+   * href="http://goo.gl/iz2Wi">"diamond" syntax</a>.
    *
    * @return a new, empty {@code TreeSet}
    */
@@ -360,9 +366,9 @@ public static <E extends Comparable> TreeSet<E> newTreeSet() {
    * method has different behavior than {@link TreeSet#TreeSet(SortedSet)}, which returns a {@code
    * TreeSet} with that comparator.
    *
-   * <p><b>Note for Java 7 and later:</b> this method is now unnecessary and should be treated as
-   * deprecated. Instead, use the {@code TreeSet} constructor directly, taking advantage of the new
-   * <a href="http://goo.gl/iz2Wi">"diamond" syntax</a>.
+   * <p><b>Note:</b> this method is now unnecessary and should be treated as deprecated. Instead,
+   * use the {@code TreeSet} constructor directly, taking advantage of <a
+   * href="http://goo.gl/iz2Wi">"diamond" syntax</a>.
    *
    * <p>This method is just a small convenience for creating an empty set and then calling {@link
    * Iterables#addAll}. This method is not very useful and will likely be deprecated in the future.
@@ -382,17 +388,18 @@ public static <E extends Comparable> TreeSet<E> newTreeSet(Iterable<? extends E>
    * <p><b>Note:</b> if mutability is not required, use {@code
    * ImmutableSortedSet.orderedBy(comparator).build()} instead.
    *
-   * <p><b>Note for Java 7 and later:</b> this method is now unnecessary and should be treated as
-   * deprecated. Instead, use the {@code TreeSet} constructor directly, taking advantage of the new
-   * <a href="http://goo.gl/iz2Wi">"diamond" syntax</a>. One caveat to this is that the {@code
-   * TreeSet} constructor uses a null {@code Comparator} to mean "natural ordering," whereas this
-   * factory rejects null. Clean your code accordingly.
+   * <p><b>Note:</b> this method is now unnecessary and should be treated as deprecated. Instead,
+   * use the {@code TreeSet} constructor directly, taking advantage of <a
+   * href="http://goo.gl/iz2Wi">"diamond" syntax</a>. One caveat to this is that the {@code TreeSet}
+   * constructor uses a null {@code Comparator} to mean "natural ordering," whereas this factory
+   * rejects null. Clean your code accordingly.
    *
    * @param comparator the comparator to use to sort the set
    * @return a new, empty {@code TreeSet}
    * @throws NullPointerException if {@code comparator} is null
    */
-  public static <E> TreeSet<E> newTreeSet(Comparator<? super E> comparator) {
+  public static <E extends @Nullable Object> TreeSet<E> newTreeSet(
+      Comparator<? super E> comparator) {
     return new TreeSet<E>(checkNotNull(comparator));
   }
 
@@ -405,7 +412,7 @@ public static <E> TreeSet<E> newTreeSet(Comparator<? super E> comparator) {
    *
    * @since 8.0
    */
-  public static <E> Set<E> newIdentityHashSet() {
+  public static <E extends @Nullable Object> Set<E> newIdentityHashSet() {
     return Collections.newSetFromMap(Maps.<E, Boolean>newIdentityHashMap());
   }
 
@@ -419,7 +426,7 @@ public static <E> Set<E> newIdentityHashSet() {
    * @since 12.0
    */
   @GwtIncompatible // CopyOnWriteArraySet
-  public static <E> CopyOnWriteArraySet<E> newCopyOnWriteArraySet() {
+  public static <E extends @Nullable Object> CopyOnWriteArraySet<E> newCopyOnWriteArraySet() {
     return new CopyOnWriteArraySet<E>();
   }
 
@@ -431,7 +438,8 @@ public static <E> CopyOnWriteArraySet<E> newCopyOnWriteArraySet() {
    * @since 12.0
    */
   @GwtIncompatible // CopyOnWriteArraySet
-  public static <E> CopyOnWriteArraySet<E> newCopyOnWriteArraySet(Iterable<? extends E> elements) {
+  public static <E extends @Nullable Object> CopyOnWriteArraySet<E> newCopyOnWriteArraySet(
+      Iterable<? extends E> elements) {
     // We copy elements to an ArrayList first, rather than incurring the
     // quadratic cost of adding them to the COWAS directly.
     Collection<? extends E> elementsCollection =
@@ -519,7 +527,8 @@ private static <E extends Enum<E>> EnumSet<E> makeComplementByHand(
    * @deprecated Use {@link Collections#newSetFromMap} instead.
    */
   @Deprecated
-  public static <E> Set<E> newSetFromMap(Map<E, Boolean> map) {
+  public static <E extends @Nullable Object> Set<E> newSetFromMap(
+      Map<E, Boolean> map) {
     return Collections.newSetFromMap(map);
   }
 
@@ -532,7 +541,7 @@ public static <E> Set<E> newSetFromMap(Map<E, Boolean> map) {
    *
    * @since 2.0
    */
-  public abstract static class SetView<E> extends AbstractSet<E> {
+  public abstract static class SetView<E extends @Nullable Object> extends AbstractSet<E> {
     private SetView() {} // no subclasses but our own
 
     /**
@@ -543,6 +552,7 @@ private SetView() {} // no subclasses but our own
      * nonstandard notion of equivalence, for example if it is a {@link TreeSet} using a comparator
      * that is inconsistent with {@link Object#equals(Object)}.
      */
+    @SuppressWarnings("nullness") // Unsafe, but we can't fix it now.
     public ImmutableSet<E> immutableCopy() {
       return ImmutableSet.copyOf(this);
     }
@@ -571,7 +581,8 @@ public <S extends Set<E>> S copyInto(S set) {
     @CanIgnoreReturnValue
     @Deprecated
     @Override
-    public final boolean add(E e) {
+    @DoNotCall("Always throws UnsupportedOperationException")
+    public final boolean add(@ParametricNullness E e) {
       throw new UnsupportedOperationException();
     }
 
@@ -584,7 +595,8 @@ public final boolean add(E e) {
     @CanIgnoreReturnValue
     @Deprecated
     @Override
-    public final boolean remove(Object object) {
+    @DoNotCall("Always throws UnsupportedOperationException")
+    public final boolean remove(@CheckForNull Object object) {
       throw new UnsupportedOperationException();
     }
 
@@ -597,6 +609,7 @@ public final boolean remove(Object object) {
     @CanIgnoreReturnValue
     @Deprecated
     @Override
+    @DoNotCall("Always throws UnsupportedOperationException")
     public final boolean addAll(Collection<? extends E> newElements) {
       throw new UnsupportedOperationException();
     }
@@ -610,6 +623,7 @@ public final boolean addAll(Collection<? extends E> newElements) {
     @CanIgnoreReturnValue
     @Deprecated
     @Override
+    @DoNotCall("Always throws UnsupportedOperationException")
     public final boolean removeAll(Collection<?> oldElements) {
       throw new UnsupportedOperationException();
     }
@@ -623,6 +637,7 @@ public final boolean removeAll(Collection<?> oldElements) {
     @CanIgnoreReturnValue
     @Deprecated
     @Override
+    @DoNotCall("Always throws UnsupportedOperationException")
     public final boolean retainAll(Collection<?> elementsToKeep) {
       throw new UnsupportedOperationException();
     }
@@ -635,6 +650,7 @@ public final boolean retainAll(Collection<?> elementsToKeep) {
      */
     @Deprecated
     @Override
+    @DoNotCall("Always throws UnsupportedOperationException")
     public final void clear() {
       throw new UnsupportedOperationException();
     }
@@ -655,10 +671,11 @@ public final void clear() {
    * that is not contained in {@code set1}.
    *
    * <p>Results are undefined if {@code set1} and {@code set2} are sets based on different
-   * equivalence relations (as {@link HashSet}, {@link TreeSet}, and the {@link Map#keySet} of an
-   * {@code IdentityHashMap} all are).
+   * equivalence relations, for example if {@code set1} is a {@link HashSet} and {@code set2} is a
+   * {@link TreeSet} or the {@link Map#keySet} of an {@code IdentityHashMap}.
    */
-  public static <E> SetView<E> union(final Set<? extends E> set1, final Set<? extends E> set2) {
+  public static <E extends @Nullable Object> SetView<E> union(
+      final Set<? extends E> set1, final Set<? extends E> set2) {
     checkNotNull(set1, "set1");
     checkNotNull(set2, "set2");
 
@@ -686,6 +703,7 @@ public UnmodifiableIterator<E> iterator() {
           final Iterator<? extends E> itr2 = set2.iterator();
 
           @Override
+          @CheckForNull
           protected E computeNext() {
             if (itr1.hasNext()) {
               return itr1.next();
@@ -702,7 +720,7 @@ protected E computeNext() {
       }
 
       @Override
-      public boolean contains(Object object) {
+      public boolean contains(@CheckForNull Object object) {
         return set1.contains(object) || set2.contains(object);
       }
 
@@ -714,6 +732,7 @@ public <S extends Set<E>> S copyInto(S set) {
       }
 
       @Override
+      @SuppressWarnings("nullness") // see supertype
       public ImmutableSet<E> immutableCopy() {
         return new ImmutableSet.Builder<E>().addAll(set1).addAll(set2).build();
       }
@@ -726,8 +745,8 @@ public ImmutableSet<E> immutableCopy() {
    * matches that of {@code set1}.
    *
    * <p>Results are undefined if {@code set1} and {@code set2} are sets based on different
-   * equivalence relations (as {@code HashSet}, {@code TreeSet}, and the keySet of an {@code
-   * IdentityHashMap} all are).
+   * equivalence relations, for example if {@code set1} is a {@link HashSet} and {@code set2} is a
+   * {@link TreeSet} or the {@link Map#keySet} of an {@code IdentityHashMap}.
    *
    * <p><b>Note:</b> The returned view performs slightly better when {@code set1} is the smaller of
    * the two sets. If you have reason to believe one of your sets will generally be smaller than the
@@ -747,7 +766,8 @@ public ImmutableSet<E> immutableCopy() {
    *
    * <p>This is unfortunate, but should come up only very rarely.
    */
-  public static <E> SetView<E> intersection(final Set<E> set1, final Set<?> set2) {
+  public static <E extends @Nullable Object> SetView<E> intersection(
+      final Set<E> set1, final Set<?> set2) {
     checkNotNull(set1, "set1");
     checkNotNull(set2, "set2");
 
@@ -758,6 +778,7 @@ public UnmodifiableIterator<E> iterator() {
           final Iterator<E> itr = set1.iterator();
 
           @Override
+          @CheckForNull
           protected E computeNext() {
             while (itr.hasNext()) {
               E e = itr.next();
@@ -787,7 +808,7 @@ public boolean isEmpty() {
       }
 
       @Override
-      public boolean contains(Object object) {
+      public boolean contains(@CheckForNull Object object) {
         return set1.contains(object) && set2.contains(object);
       }
 
@@ -805,10 +826,11 @@ public boolean containsAll(Collection<?> collection) {
    * order of the returned set matches that of {@code set1}.
    *
    * <p>Results are undefined if {@code set1} and {@code set2} are sets based on different
-   * equivalence relations (as {@code HashSet}, {@code TreeSet}, and the keySet of an {@code
-   * IdentityHashMap} all are).
+   * equivalence relations, for example if {@code set1} is a {@link HashSet} and {@code set2} is a
+   * {@link TreeSet} or the {@link Map#keySet} of an {@code IdentityHashMap}.
    */
-  public static <E> SetView<E> difference(final Set<E> set1, final Set<?> set2) {
+  public static <E extends @Nullable Object> SetView<E> difference(
+      final Set<E> set1, final Set<?> set2) {
     checkNotNull(set1, "set1");
     checkNotNull(set2, "set2");
 
@@ -819,6 +841,7 @@ public UnmodifiableIterator<E> iterator() {
           final Iterator<E> itr = set1.iterator();
 
           @Override
+          @CheckForNull
           protected E computeNext() {
             while (itr.hasNext()) {
               E e = itr.next();
@@ -848,7 +871,7 @@ public boolean isEmpty() {
       }
 
       @Override
-      public boolean contains(Object element) {
+      public boolean contains(@CheckForNull Object element) {
         return set1.contains(element) && !set2.contains(element);
       }
     };
@@ -860,12 +883,12 @@ public boolean contains(Object element) {
    * both. The iteration order of the returned set is undefined.
    *
    * <p>Results are undefined if {@code set1} and {@code set2} are sets based on different
-   * equivalence relations (as {@code HashSet}, {@code TreeSet}, and the keySet of an {@code
-   * IdentityHashMap} all are).
+   * equivalence relations, for example if {@code set1} is a {@link HashSet} and {@code set2} is a
+   * {@link TreeSet} or the {@link Map#keySet} of an {@code IdentityHashMap}.
    *
    * @since 3.0
    */
-  public static <E> SetView<E> symmetricDifference(
+  public static <E extends @Nullable Object> SetView<E> symmetricDifference(
       final Set<? extends E> set1, final Set<? extends E> set2) {
     checkNotNull(set1, "set1");
     checkNotNull(set2, "set2");
@@ -877,6 +900,7 @@ public UnmodifiableIterator<E> iterator() {
         final Iterator<? extends E> itr2 = set2.iterator();
         return new AbstractIterator<E>() {
           @Override
+          @CheckForNull
           public E computeNext() {
             while (itr1.hasNext()) {
               E elem1 = itr1.next();
@@ -917,7 +941,7 @@ public boolean isEmpty() {
       }
 
       @Override
-      public boolean contains(Object element) {
+      public boolean contains(@CheckForNull Object element) {
         return set1.contains(element) ^ set2.contains(element);
       }
     };
@@ -950,7 +974,8 @@ public boolean contains(Object element) {
    * you to migrate to streams.
    */
   // TODO(kevinb): how to omit that last sentence when building GWT javadoc?
-  public static <E> Set<E> filter(Set<E> unfiltered, Predicate<? super E> predicate) {
+  public static <E extends @Nullable Object> Set<E> filter(
+      Set<E> unfiltered, Predicate<? super E> predicate) {
     if (unfiltered instanceof SortedSet) {
       return filter((SortedSet<E>) unfiltered, predicate);
     }
@@ -989,7 +1014,8 @@ public static <E> Set<E> filter(Set<E> unfiltered, Predicate<? super E> predicat
    *
    * @since 11.0
    */
-  public static <E> SortedSet<E> filter(SortedSet<E> unfiltered, Predicate<? super E> predicate) {
+  public static <E extends @Nullable Object> SortedSet<E> filter(
+      SortedSet<E> unfiltered, Predicate<? super E> predicate) {
     if (unfiltered instanceof FilteredSet) {
       // Support clear(), removeAll(), and retainAll() when filtering a filtered
       // collection.
@@ -1027,7 +1053,7 @@ public static <E> SortedSet<E> filter(SortedSet<E> unfiltered, Predicate<? super
    */
   @GwtIncompatible // NavigableSet
   @SuppressWarnings("unchecked")
-  public static <E> NavigableSet<E> filter(
+  public static <E extends @Nullable Object> NavigableSet<E> filter(
       NavigableSet<E> unfiltered, Predicate<? super E> predicate) {
     if (unfiltered instanceof FilteredSet) {
       // Support clear(), removeAll(), and retainAll() when filtering a filtered
@@ -1040,13 +1066,14 @@ public static <E> NavigableSet<E> filter(
     return new FilteredNavigableSet<E>(checkNotNull(unfiltered), checkNotNull(predicate));
   }
 
-  private static class FilteredSet<E> extends FilteredCollection<E> implements Set<E> {
+  private static class FilteredSet<E extends @Nullable Object> extends FilteredCollection<E>
+      implements Set<E> {
     FilteredSet(Set<E> unfiltered, Predicate<? super E> predicate) {
       super(unfiltered, predicate);
     }
 
     @Override
-    public boolean equals(@NullableDecl Object object) {
+    public boolean equals(@CheckForNull Object object) {
       return equalsImpl(this, object);
     }
 
@@ -1056,39 +1083,43 @@ public int hashCode() {
     }
   }
 
-  private static class FilteredSortedSet<E> extends FilteredSet<E> implements SortedSet<E> {
+  private static class FilteredSortedSet<E extends @Nullable Object> extends FilteredSet<E>
+      implements SortedSet<E> {
 
     FilteredSortedSet(SortedSet<E> unfiltered, Predicate<? super E> predicate) {
       super(unfiltered, predicate);
     }
 
     @Override
+    @CheckForNull
     public Comparator<? super E> comparator() {
       return ((SortedSet<E>) unfiltered).comparator();
     }
 
     @Override
-    public SortedSet<E> subSet(E fromElement, E toElement) {
+    public SortedSet<E> subSet(@ParametricNullness E fromElement, @ParametricNullness E toElement) {
       return new FilteredSortedSet<E>(
           ((SortedSet<E>) unfiltered).subSet(fromElement, toElement), predicate);
     }
 
     @Override
-    public SortedSet<E> headSet(E toElement) {
+    public SortedSet<E> headSet(@ParametricNullness E toElement) {
       return new FilteredSortedSet<E>(((SortedSet<E>) unfiltered).headSet(toElement), predicate);
     }
 
     @Override
-    public SortedSet<E> tailSet(E fromElement) {
+    public SortedSet<E> tailSet(@ParametricNullness E fromElement) {
       return new FilteredSortedSet<E>(((SortedSet<E>) unfiltered).tailSet(fromElement), predicate);
     }
 
     @Override
+    @ParametricNullness
     public E first() {
       return Iterators.find(unfiltered.iterator(), predicate);
     }
 
     @Override
+    @ParametricNullness
     public E last() {
       SortedSet<E> sortedUnfiltered = (SortedSet<E>) unfiltered;
       while (true) {
@@ -1102,7 +1133,7 @@ public E last() {
   }
 
   @GwtIncompatible // NavigableSet
-  private static class FilteredNavigableSet<E> extends FilteredSortedSet<E>
+  private static class FilteredNavigableSet<E extends @Nullable Object> extends FilteredSortedSet<E>
       implements NavigableSet<E> {
     FilteredNavigableSet(NavigableSet<E> unfiltered, Predicate<? super E> predicate) {
       super(unfiltered, predicate);
@@ -1113,33 +1144,37 @@ NavigableSet<E> unfiltered() {
     }
 
     @Override
-    @NullableDecl
-    public E lower(E e) {
+    @CheckForNull
+    public E lower(@ParametricNullness E e) {
       return Iterators.find(unfiltered().headSet(e, false).descendingIterator(), predicate, null);
     }
 
     @Override
-    @NullableDecl
-    public E floor(E e) {
+    @CheckForNull
+    public E floor(@ParametricNullness E e) {
       return Iterators.find(unfiltered().headSet(e, true).descendingIterator(), predicate, null);
     }
 
     @Override
-    public E ceiling(E e) {
+    @CheckForNull
+    public E ceiling(@ParametricNullness E e) {
       return Iterables.find(unfiltered().tailSet(e, true), predicate, null);
     }
 
     @Override
-    public E higher(E e) {
+    @CheckForNull
+    public E higher(@ParametricNullness E e) {
       return Iterables.find(unfiltered().tailSet(e, false), predicate, null);
     }
 
     @Override
+    @CheckForNull
     public E pollFirst() {
       return Iterables.removeFirstMatching(unfiltered(), predicate);
     }
 
     @Override
+    @CheckForNull
     public E pollLast() {
       return Iterables.removeFirstMatching(unfiltered().descendingSet(), predicate);
     }
@@ -1155,24 +1190,28 @@ public Iterator<E> descendingIterator() {
     }
 
     @Override
+    @ParametricNullness
     public E last() {
       return Iterators.find(unfiltered().descendingIterator(), predicate);
     }
 
     @Override
     public NavigableSet<E> subSet(
-        E fromElement, boolean fromInclusive, E toElement, boolean toInclusive) {
+        @ParametricNullness E fromElement,
+        boolean fromInclusive,
+        @ParametricNullness E toElement,
+        boolean toInclusive) {
       return filter(
           unfiltered().subSet(fromElement, fromInclusive, toElement, toInclusive), predicate);
     }
 
     @Override
-    public NavigableSet<E> headSet(E toElement, boolean inclusive) {
+    public NavigableSet<E> headSet(@ParametricNullness E toElement, boolean inclusive) {
       return filter(unfiltered().headSet(toElement, inclusive), predicate);
     }
 
     @Override
-    public NavigableSet<E> tailSet(E fromElement, boolean inclusive) {
+    public NavigableSet<E> tailSet(@ParametricNullness E fromElement, boolean inclusive) {
       return filter(unfiltered().tailSet(fromElement, inclusive), predicate);
     }
   }
@@ -1338,7 +1377,7 @@ protected Collection<List<E>> delegate() {
     }
 
     @Override
-    public boolean contains(@NullableDecl Object object) {
+    public boolean contains(@CheckForNull Object object) {
       if (!(object instanceof List)) {
         return false;
       }
@@ -1357,7 +1396,7 @@ public boolean contains(@NullableDecl Object object) {
     }
 
     @Override
-    public boolean equals(@NullableDecl Object object) {
+    public boolean equals(@CheckForNull Object object) {
       // Warning: this is broken if size() == 0, so it is critical that we
       // substitute an empty ImmutableSet to the user in place of this
       if (object instanceof CartesianSet) {
@@ -1457,7 +1496,7 @@ public int size() {
     }
 
     @Override
-    public boolean contains(@NullableDecl Object o) {
+    public boolean contains(@CheckForNull Object o) {
       Integer index = inputSet.get(o);
       return index != null && (mask & (1 << index)) != 0;
     }
@@ -1493,7 +1532,7 @@ protected Set<E> get(final int setBits) {
     }
 
     @Override
-    public boolean contains(@NullableDecl Object obj) {
+    public boolean contains(@CheckForNull Object obj) {
       if (obj instanceof Set) {
         Set<?> set = (Set<?>) obj;
         return inputSet.keySet().containsAll(set);
@@ -1502,7 +1541,7 @@ public boolean contains(@NullableDecl Object obj) {
     }
 
     @Override
-    public boolean equals(@NullableDecl Object obj) {
+    public boolean equals(@CheckForNull Object obj) {
       if (obj instanceof PowerSet) {
         PowerSet<?> that = (PowerSet<?>) obj;
         return inputSet.keySet().equals(that.inputSet.keySet());
@@ -1562,7 +1601,7 @@ public static <E> Set<Set<E>> combinations(Set<E> set, final int size) {
     }
     return new AbstractSet<Set<E>>() {
       @Override
-      public boolean contains(@NullableDecl Object o) {
+      public boolean contains(@CheckForNull Object o) {
         if (o instanceof Set) {
           Set<?> s = (Set<?>) o;
           return s.size() == size && index.keySet().containsAll(s);
@@ -1576,6 +1615,7 @@ public Iterator<Set<E>> iterator() {
           final BitSet bits = new BitSet(index.size());
 
           @Override
+          @CheckForNull
           protected Set<E> computeNext() {
             if (bits.isEmpty()) {
               bits.set(0, size);
@@ -1606,7 +1646,7 @@ protected Set<E> computeNext() {
             final BitSet copy = (BitSet) bits.clone();
             return new AbstractSet<E>() {
               @Override
-              public boolean contains(@NullableDecl Object o) {
+              public boolean contains(@CheckForNull Object o) {
                 Integer i = index.get(o);
                 return i != null && copy.get(i);
               }
@@ -1617,6 +1657,7 @@ public Iterator<E> iterator() {
                   int i = -1;
 
                   @Override
+                  @CheckForNull
                   protected E computeNext() {
                     i = copy.nextSetBit(i + 1);
                     if (i == -1) {
@@ -1661,7 +1702,7 @@ static int hashCodeImpl(Set<?> s) {
   }
 
   /** An implementation for {@link Set#equals(Object)}. */
-  static boolean equalsImpl(Set<?> s, @NullableDecl Object object) {
+  static boolean equalsImpl(Set<?> s, @CheckForNull Object object) {
     if (s == object) {
       return true;
     }
@@ -1690,15 +1731,16 @@ static boolean equalsImpl(Set<?> s, @NullableDecl Object object) {
    * @return an unmodifiable view of the specified navigable set
    * @since 12.0
    */
-  public static <E> NavigableSet<E> unmodifiableNavigableSet(NavigableSet<E> set) {
+  public static <E extends @Nullable Object> NavigableSet<E> unmodifiableNavigableSet(
+      NavigableSet<E> set) {
     if (set instanceof ImmutableCollection || set instanceof UnmodifiableNavigableSet) {
       return set;
     }
     return new UnmodifiableNavigableSet<E>(set);
   }
 
-  static final class UnmodifiableNavigableSet<E> extends ForwardingSortedSet<E>
-      implements NavigableSet<E>, Serializable {
+  static final class UnmodifiableNavigableSet<E extends @Nullable Object>
+      extends ForwardingSortedSet<E> implements NavigableSet<E>, Serializable {
     private final NavigableSet<E> delegate;
     private final SortedSet<E> unmodifiableDelegate;
 
@@ -1713,36 +1755,42 @@ protected SortedSet<E> delegate() {
     }
 
     @Override
-    public E lower(E e) {
+    @CheckForNull
+    public E lower(@ParametricNullness E e) {
       return delegate.lower(e);
     }
 
     @Override
-    public E floor(E e) {
+    @CheckForNull
+    public E floor(@ParametricNullness E e) {
       return delegate.floor(e);
     }
 
     @Override
-    public E ceiling(E e) {
+    @CheckForNull
+    public E ceiling(@ParametricNullness E e) {
       return delegate.ceiling(e);
     }
 
     @Override
-    public E higher(E e) {
+    @CheckForNull
+    public E higher(@ParametricNullness E e) {
       return delegate.higher(e);
     }
 
     @Override
+    @CheckForNull
     public E pollFirst() {
       throw new UnsupportedOperationException();
     }
 
     @Override
+    @CheckForNull
     public E pollLast() {
       throw new UnsupportedOperationException();
     }
 
-    @NullableDecl private transient UnmodifiableNavigableSet<E> descendingSet;
+    @CheckForNull private transient UnmodifiableNavigableSet<E> descendingSet;
 
     @Override
     public NavigableSet<E> descendingSet() {
@@ -1761,18 +1809,21 @@ public Iterator<E> descendingIterator() {
 
     @Override
     public NavigableSet<E> subSet(
-        E fromElement, boolean fromInclusive, E toElement, boolean toInclusive) {
+        @ParametricNullness E fromElement,
+        boolean fromInclusive,
+        @ParametricNullness E toElement,
+        boolean toInclusive) {
       return unmodifiableNavigableSet(
           delegate.subSet(fromElement, fromInclusive, toElement, toInclusive));
     }
 
     @Override
-    public NavigableSet<E> headSet(E toElement, boolean inclusive) {
+    public NavigableSet<E> headSet(@ParametricNullness E toElement, boolean inclusive) {
       return unmodifiableNavigableSet(delegate.headSet(toElement, inclusive));
     }
 
     @Override
-    public NavigableSet<E> tailSet(E fromElement, boolean inclusive) {
+    public NavigableSet<E> tailSet(@ParametricNullness E fromElement, boolean inclusive) {
       return unmodifiableNavigableSet(delegate.tailSet(fromElement, inclusive));
     }
 
@@ -1825,7 +1876,8 @@ public NavigableSet<E> tailSet(E fromElement, boolean inclusive) {
    * @since 13.0
    */
   @GwtIncompatible // NavigableSet
-  public static <E> NavigableSet<E> synchronizedNavigableSet(NavigableSet<E> navigableSet) {
+  public static <E extends @Nullable Object> NavigableSet<E> synchronizedNavigableSet(
+      NavigableSet<E> navigableSet) {
     return Synchronized.navigableSet(navigableSet);
   }
 
@@ -1858,7 +1910,7 @@ static boolean removeAllImpl(Set<?> set, Collection<?> collection) {
   }
 
   @GwtIncompatible // NavigableSet
-  static class DescendingSet<E> extends ForwardingNavigableSet<E> {
+  static class DescendingSet<E extends @Nullable Object> extends ForwardingNavigableSet<E> {
     private final NavigableSet<E> forward;
 
     DescendingSet(NavigableSet<E> forward) {
@@ -1871,31 +1923,37 @@ protected NavigableSet<E> delegate() {
     }
 
     @Override
-    public E lower(E e) {
+    @CheckForNull
+    public E lower(@ParametricNullness E e) {
       return forward.higher(e);
     }
 
     @Override
-    public E floor(E e) {
+    @CheckForNull
+    public E floor(@ParametricNullness E e) {
       return forward.ceiling(e);
     }
 
     @Override
-    public E ceiling(E e) {
+    @CheckForNull
+    public E ceiling(@ParametricNullness E e) {
       return forward.floor(e);
     }
 
     @Override
-    public E higher(E e) {
+    @CheckForNull
+    public E higher(@ParametricNullness E e) {
       return forward.lower(e);
     }
 
     @Override
+    @CheckForNull
     public E pollFirst() {
       return forward.pollLast();
     }
 
     @Override
+    @CheckForNull
     public E pollLast() {
       return forward.pollFirst();
     }
@@ -1912,32 +1970,35 @@ public Iterator<E> descendingIterator() {
 
     @Override
     public NavigableSet<E> subSet(
-        E fromElement, boolean fromInclusive, E toElement, boolean toInclusive) {
+        @ParametricNullness E fromElement,
+        boolean fromInclusive,
+        @ParametricNullness E toElement,
+        boolean toInclusive) {
       return forward.subSet(toElement, toInclusive, fromElement, fromInclusive).descendingSet();
     }
 
     @Override
-    public SortedSet<E> subSet(E fromElement, E toElement) {
+    public SortedSet<E> subSet(@ParametricNullness E fromElement, @ParametricNullness E toElement) {
       return standardSubSet(fromElement, toElement);
     }
 
     @Override
-    public NavigableSet<E> headSet(E toElement, boolean inclusive) {
+    public NavigableSet<E> headSet(@ParametricNullness E toElement, boolean inclusive) {
       return forward.tailSet(toElement, inclusive).descendingSet();
     }
 
     @Override
-    public SortedSet<E> headSet(E toElement) {
+    public SortedSet<E> headSet(@ParametricNullness E toElement) {
       return standardHeadSet(toElement);
     }
 
     @Override
-    public NavigableSet<E> tailSet(E fromElement, boolean inclusive) {
+    public NavigableSet<E> tailSet(@ParametricNullness E fromElement, boolean inclusive) {
       return forward.headSet(fromElement, inclusive).descendingSet();
     }
 
     @Override
-    public SortedSet<E> tailSet(E fromElement) {
+    public SortedSet<E> tailSet(@ParametricNullness E fromElement) {
       return standardTailSet(fromElement);
     }
 
@@ -1953,16 +2014,18 @@ public Comparator<? super E> comparator() {
     }
 
     // If we inline this, we get a javac error.
-    private static <T> Ordering<T> reverse(Comparator<T> forward) {
+    private static <T extends @Nullable Object> Ordering<T> reverse(Comparator<T> forward) {
       return Ordering.from(forward).reverse();
     }
 
     @Override
+    @ParametricNullness
     public E first() {
       return forward.last();
     }
 
     @Override
+    @ParametricNullness
     public E last() {
       return forward.first();
     }
@@ -1973,12 +2036,13 @@ public Iterator<E> iterator() {
     }
 
     @Override
-    public Object[] toArray() {
+    public @Nullable Object[] toArray() {
       return standardToArray();
     }
 
     @Override
-    public <T> T[] toArray(T[] array) {
+    @SuppressWarnings("nullness") // b/192354773 in our checker affects toArray declarations
+    public <T extends @Nullable Object> T[] toArray(T[] array) {
       return standardToArray(array);
     }
 
diff --git a/android/guava/src/com/google/common/collect/SingletonImmutableSet.java b/android/guava/src/com/google/common/collect/SingletonImmutableSet.java
index 0f882b3eaad9..088cb802f27f 100644
--- a/android/guava/src/com/google/common/collect/SingletonImmutableSet.java
+++ b/android/guava/src/com/google/common/collect/SingletonImmutableSet.java
@@ -18,7 +18,8 @@
 
 import com.google.common.annotations.GwtCompatible;
 import com.google.common.base.Preconditions;
-import com.google.errorprone.annotations.concurrent.LazyInit;
+import javax.annotation.CheckForNull;
+import org.checkerframework.checker.nullness.qual.Nullable;
 
 /**
  * Implementation of {@link ImmutableSet} with exactly one element.
@@ -28,35 +29,24 @@
  */
 @GwtCompatible(serializable = true, emulated = true)
 @SuppressWarnings("serial") // uses writeReplace(), not default serialization
+@ElementTypesAreNonnullByDefault
 final class SingletonImmutableSet<E> extends ImmutableSet<E> {
+  // We deliberately avoid caching the asList and hashCode here, to ensure that with
+  // compressed oops, a SingletonImmutableSet packs all the way down to the optimal 16 bytes.
 
   final transient E element;
-  // This is transient because it will be recalculated on the first
-  // call to hashCode().
-  //
-  // A race condition is avoided since threads will either see that the value
-  // is zero and recalculate it themselves, or two threads will see it at
-  // the same time, and both recalculate it.  If the cachedHashCode is 0,
-  // it will always be recalculated, unfortunately.
-  @LazyInit private transient int cachedHashCode;
 
   SingletonImmutableSet(E element) {
     this.element = Preconditions.checkNotNull(element);
   }
 
-  SingletonImmutableSet(E element, int hashCode) {
-    // Guaranteed to be non-null by the presence of the pre-computed hash code.
-    this.element = element;
-    cachedHashCode = hashCode;
-  }
-
   @Override
   public int size() {
     return 1;
   }
 
   @Override
-  public boolean contains(Object target) {
+  public boolean contains(@CheckForNull Object target) {
     return element.equals(target);
   }
 
@@ -66,7 +56,7 @@ public UnmodifiableIterator<E> iterator() {
   }
 
   @Override
-  ImmutableList<E> createAsList() {
+  public ImmutableList<E> asList() {
     return ImmutableList.of(element);
   }
 
@@ -76,24 +66,14 @@ boolean isPartialView() {
   }
 
   @Override
-  int copyIntoArray(Object[] dst, int offset) {
+  int copyIntoArray(@Nullable Object[] dst, int offset) {
     dst[offset] = element;
     return offset + 1;
   }
 
   @Override
   public final int hashCode() {
-    // Racy single-check.
-    int code = cachedHashCode;
-    if (code == 0) {
-      cachedHashCode = code = element.hashCode();
-    }
-    return code;
-  }
-
-  @Override
-  boolean isHashCodeFast() {
-    return cachedHashCode != 0;
+    return element.hashCode();
   }
 
   @Override
diff --git a/android/guava/src/com/google/common/collect/SingletonImmutableTable.java b/android/guava/src/com/google/common/collect/SingletonImmutableTable.java
index 58a182cccd3e..cfaeadb41df7 100644
--- a/android/guava/src/com/google/common/collect/SingletonImmutableTable.java
+++ b/android/guava/src/com/google/common/collect/SingletonImmutableTable.java
@@ -27,6 +27,7 @@
  * @author Gregory Kick
  */
 @GwtCompatible
+@ElementTypesAreNonnullByDefault
 class SingletonImmutableTable<R, C, V> extends ImmutableTable<R, C, V> {
   final R singleRowKey;
   final C singleColumnKey;
diff --git a/android/guava/src/com/google/common/collect/SortedIterable.java b/android/guava/src/com/google/common/collect/SortedIterable.java
index d46e8afcd9c5..64ec08ef315b 100644
--- a/android/guava/src/com/google/common/collect/SortedIterable.java
+++ b/android/guava/src/com/google/common/collect/SortedIterable.java
@@ -17,6 +17,7 @@
 import com.google.common.annotations.GwtCompatible;
 import java.util.Comparator;
 import java.util.Iterator;
+import org.checkerframework.checker.nullness.qual.Nullable;
 
 /**
  * An {@code Iterable} whose elements are sorted relative to a {@code Comparator}, typically
@@ -25,7 +26,8 @@
  * @author Louis Wasserman
  */
 @GwtCompatible
-interface SortedIterable<T> extends Iterable<T> {
+@ElementTypesAreNonnullByDefault
+interface SortedIterable<T extends @Nullable Object> extends Iterable<T> {
   /**
    * Returns the {@code Comparator} by which the elements of this iterable are ordered, or {@code
    * Ordering.natural()} if the elements are ordered by their natural ordering.
diff --git a/android/guava/src/com/google/common/collect/SortedIterables.java b/android/guava/src/com/google/common/collect/SortedIterables.java
index 2c0aa7ccac89..68b231a381e5 100644
--- a/android/guava/src/com/google/common/collect/SortedIterables.java
+++ b/android/guava/src/com/google/common/collect/SortedIterables.java
@@ -19,6 +19,7 @@
 import com.google.common.annotations.GwtCompatible;
 import java.util.Comparator;
 import java.util.SortedSet;
+import org.checkerframework.checker.nullness.qual.Nullable;
 
 /**
  * Utilities for dealing with sorted collections of all types.
@@ -26,6 +27,7 @@
  * @author Louis Wasserman
  */
 @GwtCompatible
+@ElementTypesAreNonnullByDefault
 final class SortedIterables {
   private SortedIterables() {}
 
@@ -49,7 +51,8 @@ public static boolean hasSameComparator(Comparator<?> comparator, Iterable<?> el
 
   @SuppressWarnings("unchecked")
   // if sortedSet.comparator() is null, the set must be naturally ordered
-  public static <E> Comparator<? super E> comparator(SortedSet<E> sortedSet) {
+  public static <E extends @Nullable Object> Comparator<? super E> comparator(
+      SortedSet<E> sortedSet) {
     Comparator<? super E> result = sortedSet.comparator();
     if (result == null) {
       result = (Comparator<? super E>) Ordering.natural();
diff --git a/android/guava/src/com/google/common/collect/SortedLists.java b/android/guava/src/com/google/common/collect/SortedLists.java
index 744a458409c2..0ebaab20f938 100644
--- a/android/guava/src/com/google/common/collect/SortedLists.java
+++ b/android/guava/src/com/google/common/collect/SortedLists.java
@@ -23,7 +23,7 @@
 import java.util.Comparator;
 import java.util.List;
 import java.util.RandomAccess;
-import org.checkerframework.checker.nullness.compatqual.NullableDecl;
+import org.checkerframework.checker.nullness.qual.Nullable;
 
 /**
  * Static methods pertaining to sorted {@link List} instances.
@@ -36,6 +36,7 @@
  */
 @GwtCompatible
 @Beta
+@ElementTypesAreNonnullByDefault
 final class SortedLists {
   private SortedLists() {}
 
@@ -50,16 +51,22 @@ enum KeyPresentBehavior {
      */
     ANY_PRESENT {
       @Override
-      <E> int resultIndex(
-          Comparator<? super E> comparator, E key, List<? extends E> list, int foundIndex) {
+      <E extends @Nullable Object> int resultIndex(
+          Comparator<? super E> comparator,
+          @ParametricNullness E key,
+          List<? extends E> list,
+          int foundIndex) {
         return foundIndex;
       }
     },
     /** Return the index of the last list element that compares as equal to the key. */
     LAST_PRESENT {
       @Override
-      <E> int resultIndex(
-          Comparator<? super E> comparator, E key, List<? extends E> list, int foundIndex) {
+      <E extends @Nullable Object> int resultIndex(
+          Comparator<? super E> comparator,
+          @ParametricNullness E key,
+          List<? extends E> list,
+          int foundIndex) {
         // Of course, we have to use binary search to find the precise
         // breakpoint...
         int lower = foundIndex;
@@ -80,8 +87,11 @@ <E> int resultIndex(
     /** Return the index of the first list element that compares as equal to the key. */
     FIRST_PRESENT {
       @Override
-      <E> int resultIndex(
-          Comparator<? super E> comparator, E key, List<? extends E> list, int foundIndex) {
+      <E extends @Nullable Object> int resultIndex(
+          Comparator<? super E> comparator,
+          @ParametricNullness E key,
+          List<? extends E> list,
+          int foundIndex) {
         // Of course, we have to use binary search to find the precise
         // breakpoint...
         int lower = 0;
@@ -106,8 +116,11 @@ <E> int resultIndex(
      */
     FIRST_AFTER {
       @Override
-      public <E> int resultIndex(
-          Comparator<? super E> comparator, E key, List<? extends E> list, int foundIndex) {
+      public <E extends @Nullable Object> int resultIndex(
+          Comparator<? super E> comparator,
+          @ParametricNullness E key,
+          List<? extends E> list,
+          int foundIndex) {
         return LAST_PRESENT.resultIndex(comparator, key, list, foundIndex) + 1;
       }
     },
@@ -117,14 +130,20 @@ public <E> int resultIndex(
      */
     LAST_BEFORE {
       @Override
-      public <E> int resultIndex(
-          Comparator<? super E> comparator, E key, List<? extends E> list, int foundIndex) {
+      public <E extends @Nullable Object> int resultIndex(
+          Comparator<? super E> comparator,
+          @ParametricNullness E key,
+          List<? extends E> list,
+          int foundIndex) {
         return FIRST_PRESENT.resultIndex(comparator, key, list, foundIndex) - 1;
       }
     };
 
-    abstract <E> int resultIndex(
-        Comparator<? super E> comparator, E key, List<? extends E> list, int foundIndex);
+    abstract <E extends @Nullable Object> int resultIndex(
+        Comparator<? super E> comparator,
+        @ParametricNullness E key,
+        List<? extends E> list,
+        int foundIndex);
   }
 
   /**
@@ -196,12 +215,13 @@ public static <E extends Comparable> int binarySearch(
    * <p>Equivalent to {@link #binarySearch(List, Function, Object, Comparator, KeyPresentBehavior,
    * KeyAbsentBehavior)} using {@link Ordering#natural}.
    */
-  public static <E, K extends Comparable> int binarySearch(
+  public static <E extends @Nullable Object, K extends Comparable> int binarySearch(
       List<E> list,
       Function<? super E, K> keyFunction,
-      @NullableDecl K key,
+      K key,
       KeyPresentBehavior presentBehavior,
       KeyAbsentBehavior absentBehavior) {
+    checkNotNull(key);
     return binarySearch(
         list, keyFunction, key, Ordering.natural(), presentBehavior, absentBehavior);
   }
@@ -213,10 +233,10 @@ public static <E, K extends Comparable> int binarySearch(
    * KeyAbsentBehavior)} using {@link Lists#transform(List, Function) Lists.transform(list,
    * keyFunction)}.
    */
-  public static <E, K> int binarySearch(
+  public static <E extends @Nullable Object, K extends @Nullable Object> int binarySearch(
       List<E> list,
       Function<? super E, K> keyFunction,
-      @NullableDecl K key,
+      @ParametricNullness K key,
       Comparator<? super K> keyComparator,
       KeyPresentBehavior presentBehavior,
       KeyAbsentBehavior absentBehavior) {
@@ -247,9 +267,9 @@ public static <E, K> int binarySearch(
    * @return the index determined by the {@code KeyPresentBehavior}, if the key is in the list;
    *     otherwise the index determined by the {@code KeyAbsentBehavior}.
    */
-  public static <E> int binarySearch(
+  public static <E extends @Nullable Object> int binarySearch(
       List<? extends E> list,
-      @NullableDecl E key,
+      @ParametricNullness E key,
       Comparator<? super E> comparator,
       KeyPresentBehavior presentBehavior,
       KeyAbsentBehavior absentBehavior) {
diff --git a/android/guava/src/com/google/common/collect/SortedMapDifference.java b/android/guava/src/com/google/common/collect/SortedMapDifference.java
index 4715e93e5c9c..46cac8a3da54 100644
--- a/android/guava/src/com/google/common/collect/SortedMapDifference.java
+++ b/android/guava/src/com/google/common/collect/SortedMapDifference.java
@@ -18,6 +18,7 @@
 
 import com.google.common.annotations.GwtCompatible;
 import java.util.SortedMap;
+import org.checkerframework.checker.nullness.qual.Nullable;
 
 /**
  * An object representing the differences between two sorted maps.
@@ -26,7 +27,9 @@
  * @since 8.0
  */
 @GwtCompatible
-public interface SortedMapDifference<K, V> extends MapDifference<K, V> {
+@ElementTypesAreNonnullByDefault
+public interface SortedMapDifference<K extends @Nullable Object, V extends @Nullable Object>
+    extends MapDifference<K, V> {
 
   @Override
   SortedMap<K, V> entriesOnlyOnLeft();
diff --git a/android/guava/src/com/google/common/collect/SortedMultiset.java b/android/guava/src/com/google/common/collect/SortedMultiset.java
index 2635b37ede33..7cc512d8ee2e 100644
--- a/android/guava/src/com/google/common/collect/SortedMultiset.java
+++ b/android/guava/src/com/google/common/collect/SortedMultiset.java
@@ -22,6 +22,8 @@
 import java.util.Iterator;
 import java.util.NavigableSet;
 import java.util.Set;
+import javax.annotation.CheckForNull;
+import org.checkerframework.checker.nullness.qual.Nullable;
 
 /**
  * A {@link Multiset} which maintains the ordering of its elements, according to either their
@@ -35,14 +37,15 @@
  * Collection} contract, which is specified in terms of {@link Object#equals}.
  *
  * <p>See the Guava User Guide article on <a href=
- * "https://github.com/google/guava/wiki/NewCollectionTypesExplained#multiset"> {@code
- * Multiset}</a>.
+ * "https://github.com/google/guava/wiki/NewCollectionTypesExplained#multiset">{@code Multiset}</a>.
  *
  * @author Louis Wasserman
  * @since 11.0
  */
 @GwtCompatible(emulated = true)
-public interface SortedMultiset<E> extends SortedMultisetBridge<E>, SortedIterable<E> {
+@ElementTypesAreNonnullByDefault
+public interface SortedMultiset<E extends @Nullable Object>
+    extends SortedMultisetBridge<E>, SortedIterable<E> {
   /**
    * Returns the comparator that orders this multiset, or {@link Ordering#natural()} if the natural
    * ordering of the elements is used.
@@ -54,24 +57,28 @@ public interface SortedMultiset<E> extends SortedMultisetBridge<E>, SortedIterab
    * Returns the entry of the first element in this multiset, or {@code null} if this multiset is
    * empty.
    */
+  @CheckForNull
   Entry<E> firstEntry();
 
   /**
    * Returns the entry of the last element in this multiset, or {@code null} if this multiset is
    * empty.
    */
+  @CheckForNull
   Entry<E> lastEntry();
 
   /**
    * Returns and removes the entry associated with the lowest element in this multiset, or returns
    * {@code null} if this multiset is empty.
    */
+  @CheckForNull
   Entry<E> pollFirstEntry();
 
   /**
    * Returns and removes the entry associated with the greatest element in this multiset, or returns
    * {@code null} if this multiset is empty.
    */
+  @CheckForNull
   Entry<E> pollLastEntry();
 
   /**
@@ -115,7 +122,7 @@ public interface SortedMultiset<E> extends SortedMultisetBridge<E>, SortedIterab
    * <p>The returned multiset will throw an {@link IllegalArgumentException} on attempts to add
    * elements outside its range.
    */
-  SortedMultiset<E> headMultiset(E upperBound, BoundType boundType);
+  SortedMultiset<E> headMultiset(@ParametricNullness E upperBound, BoundType boundType);
 
   /**
    * Returns a view of this multiset restricted to the range between {@code lowerBound} and {@code
@@ -130,7 +137,10 @@ public interface SortedMultiset<E> extends SortedMultisetBridge<E>, SortedIterab
    * lowerBoundType).headMultiset(upperBound, upperBoundType)}.
    */
   SortedMultiset<E> subMultiset(
-      E lowerBound, BoundType lowerBoundType, E upperBound, BoundType upperBoundType);
+      @ParametricNullness E lowerBound,
+      BoundType lowerBoundType,
+      @ParametricNullness E upperBound,
+      BoundType upperBoundType);
 
   /**
    * Returns a view of this multiset restricted to the elements greater than {@code lowerBound},
@@ -141,5 +151,5 @@ SortedMultiset<E> subMultiset(
    * <p>The returned multiset will throw an {@link IllegalArgumentException} on attempts to add
    * elements outside its range.
    */
-  SortedMultiset<E> tailMultiset(E lowerBound, BoundType boundType);
+  SortedMultiset<E> tailMultiset(@ParametricNullness E lowerBound, BoundType boundType);
 }
diff --git a/android/guava/src/com/google/common/collect/SortedMultisetBridge.java b/android/guava/src/com/google/common/collect/SortedMultisetBridge.java
index 064cb7588f5d..72d50beb692f 100644
--- a/android/guava/src/com/google/common/collect/SortedMultisetBridge.java
+++ b/android/guava/src/com/google/common/collect/SortedMultisetBridge.java
@@ -18,6 +18,7 @@
 
 import com.google.common.annotations.GwtIncompatible;
 import java.util.SortedSet;
+import org.checkerframework.checker.nullness.qual.Nullable;
 
 /**
  * Superinterface of {@link SortedMultiset} to introduce a bridge method for {@code elementSet()},
@@ -27,7 +28,8 @@
  * @author Louis Wasserman
  */
 @GwtIncompatible
-interface SortedMultisetBridge<E> extends Multiset<E> {
+@ElementTypesAreNonnullByDefault
+interface SortedMultisetBridge<E extends @Nullable Object> extends Multiset<E> {
   @Override
   SortedSet<E> elementSet();
 }
diff --git a/android/guava/src/com/google/common/collect/SortedMultisets.java b/android/guava/src/com/google/common/collect/SortedMultisets.java
index 3c45c9f02e0f..f602a42a1145 100644
--- a/android/guava/src/com/google/common/collect/SortedMultisets.java
+++ b/android/guava/src/com/google/common/collect/SortedMultisets.java
@@ -28,7 +28,8 @@
 import java.util.NavigableSet;
 import java.util.NoSuchElementException;
 import java.util.SortedSet;
-import org.checkerframework.checker.nullness.compatqual.NullableDecl;
+import javax.annotation.CheckForNull;
+import org.checkerframework.checker.nullness.qual.Nullable;
 
 /**
  * Provides static utility methods for creating and working with {@link SortedMultiset} instances.
@@ -36,11 +37,14 @@
  * @author Louis Wasserman
  */
 @GwtCompatible(emulated = true)
+@ElementTypesAreNonnullByDefault
 final class SortedMultisets {
   private SortedMultisets() {}
 
   /** A skeleton implementation for {@link SortedMultiset#elementSet}. */
-  static class ElementSet<E> extends Multisets.ElementSet<E> implements SortedSet<E> {
+  @SuppressWarnings("JdkObsolete") // TODO(b/6160855): Switch GWT emulations to NavigableSet.
+  static class ElementSet<E extends @Nullable Object> extends Multisets.ElementSet<E>
+      implements SortedSet<E> {
     @Weak private final SortedMultiset<E> multiset;
 
     ElementSet(SortedMultiset<E> multiset) {
@@ -63,26 +67,28 @@ public Comparator<? super E> comparator() {
     }
 
     @Override
-    public SortedSet<E> subSet(E fromElement, E toElement) {
+    public SortedSet<E> subSet(@ParametricNullness E fromElement, @ParametricNullness E toElement) {
       return multiset().subMultiset(fromElement, CLOSED, toElement, OPEN).elementSet();
     }
 
     @Override
-    public SortedSet<E> headSet(E toElement) {
+    public SortedSet<E> headSet(@ParametricNullness E toElement) {
       return multiset().headMultiset(toElement, OPEN).elementSet();
     }
 
     @Override
-    public SortedSet<E> tailSet(E fromElement) {
+    public SortedSet<E> tailSet(@ParametricNullness E fromElement) {
       return multiset().tailMultiset(fromElement, CLOSED).elementSet();
     }
 
     @Override
+    @ParametricNullness
     public E first() {
       return getElementOrThrow(multiset().firstEntry());
     }
 
     @Override
+    @ParametricNullness
     public E last() {
       return getElementOrThrow(multiset().lastEntry());
     }
@@ -90,34 +96,39 @@ public E last() {
 
   /** A skeleton navigable implementation for {@link SortedMultiset#elementSet}. */
   @GwtIncompatible // Navigable
-  static class NavigableElementSet<E> extends ElementSet<E> implements NavigableSet<E> {
+  static class NavigableElementSet<E extends @Nullable Object> extends ElementSet<E>
+      implements NavigableSet<E> {
     NavigableElementSet(SortedMultiset<E> multiset) {
       super(multiset);
     }
 
     @Override
-    public E lower(E e) {
+    @CheckForNull
+    public E lower(@ParametricNullness E e) {
       return getElementOrNull(multiset().headMultiset(e, OPEN).lastEntry());
     }
 
     @Override
-    public E floor(E e) {
+    @CheckForNull
+    public E floor(@ParametricNullness E e) {
       return getElementOrNull(multiset().headMultiset(e, CLOSED).lastEntry());
     }
 
     @Override
-    public E ceiling(E e) {
+    @CheckForNull
+    public E ceiling(@ParametricNullness E e) {
       return getElementOrNull(multiset().tailMultiset(e, CLOSED).firstEntry());
     }
 
     @Override
-    public E higher(E e) {
+    @CheckForNull
+    public E higher(@ParametricNullness E e) {
       return getElementOrNull(multiset().tailMultiset(e, OPEN).firstEntry());
     }
 
     @Override
     public NavigableSet<E> descendingSet() {
-      return new NavigableElementSet<E>(multiset().descendingMultiset());
+      return new NavigableElementSet<>(multiset().descendingMultiset());
     }
 
     @Override
@@ -126,19 +137,24 @@ public Iterator<E> descendingIterator() {
     }
 
     @Override
+    @CheckForNull
     public E pollFirst() {
       return getElementOrNull(multiset().pollFirstEntry());
     }
 
     @Override
+    @CheckForNull
     public E pollLast() {
       return getElementOrNull(multiset().pollLastEntry());
     }
 
     @Override
     public NavigableSet<E> subSet(
-        E fromElement, boolean fromInclusive, E toElement, boolean toInclusive) {
-      return new NavigableElementSet<E>(
+        @ParametricNullness E fromElement,
+        boolean fromInclusive,
+        @ParametricNullness E toElement,
+        boolean toInclusive) {
+      return new NavigableElementSet<>(
           multiset()
               .subMultiset(
                   fromElement, BoundType.forBoolean(fromInclusive),
@@ -146,26 +162,27 @@ public NavigableSet<E> subSet(
     }
 
     @Override
-    public NavigableSet<E> headSet(E toElement, boolean inclusive) {
-      return new NavigableElementSet<E>(
+    public NavigableSet<E> headSet(@ParametricNullness E toElement, boolean inclusive) {
+      return new NavigableElementSet<>(
           multiset().headMultiset(toElement, BoundType.forBoolean(inclusive)));
     }
 
     @Override
-    public NavigableSet<E> tailSet(E fromElement, boolean inclusive) {
-      return new NavigableElementSet<E>(
+    public NavigableSet<E> tailSet(@ParametricNullness E fromElement, boolean inclusive) {
+      return new NavigableElementSet<>(
           multiset().tailMultiset(fromElement, BoundType.forBoolean(inclusive)));
     }
   }
 
-  private static <E> E getElementOrThrow(Entry<E> entry) {
+  private static <E extends @Nullable Object> E getElementOrThrow(@CheckForNull Entry<E> entry) {
     if (entry == null) {
       throw new NoSuchElementException();
     }
     return entry.getElement();
   }
 
-  private static <E> E getElementOrNull(@NullableDecl Entry<E> entry) {
+  @CheckForNull
+  private static <E extends @Nullable Object> E getElementOrNull(@CheckForNull Entry<E> entry) {
     return (entry == null) ? null : entry.getElement();
   }
 }
diff --git a/android/guava/src/com/google/common/collect/SortedSetMultimap.java b/android/guava/src/com/google/common/collect/SortedSetMultimap.java
index 33be3d0cb29c..8454aeccb60e 100644
--- a/android/guava/src/com/google/common/collect/SortedSetMultimap.java
+++ b/android/guava/src/com/google/common/collect/SortedSetMultimap.java
@@ -24,7 +24,8 @@
 import java.util.Set;
 import java.util.SortedMap;
 import java.util.SortedSet;
-import org.checkerframework.checker.nullness.compatqual.NullableDecl;
+import javax.annotation.CheckForNull;
+import org.checkerframework.checker.nullness.qual.Nullable;
 
 /**
  * A {@code SetMultimap} whose set of values for a given key are kept sorted; that is, they comprise
@@ -37,15 +38,20 @@
  * Though the method signature doesn't say so explicitly, the map returned by {@link #asMap} has
  * {@code SortedSet} values.
  *
+ * <p><b>Warning:</b> As in all {@link SetMultimap}s, do not modify either a key <i>or a value</i>
+ * of a {@code SortedSetMultimap} in a way that affects its {@link Object#equals} behavior (or its
+ * position in the order of the values). Undefined behavior and bugs will result.
+ *
  * <p>See the Guava User Guide article on <a href=
- * "https://github.com/google/guava/wiki/NewCollectionTypesExplained#multimap"> {@code
- * Multimap}</a>.
+ * "https://github.com/google/guava/wiki/NewCollectionTypesExplained#multimap">{@code Multimap}</a>.
  *
  * @author Jared Levy
  * @since 2.0
  */
 @GwtCompatible
-public interface SortedSetMultimap<K, V> extends SetMultimap<K, V> {
+@ElementTypesAreNonnullByDefault
+public interface SortedSetMultimap<K extends @Nullable Object, V extends @Nullable Object>
+    extends SetMultimap<K, V> {
   // Following Javadoc copied from Multimap.
 
   /**
@@ -59,7 +65,7 @@ public interface SortedSetMultimap<K, V> extends SetMultimap<K, V> {
    * {@link Multimap} interface.
    */
   @Override
-  SortedSet<V> get(@NullableDecl K key);
+  SortedSet<V> get(@ParametricNullness K key);
 
   /**
    * Removes all values associated with a given key.
@@ -70,7 +76,7 @@ public interface SortedSetMultimap<K, V> extends SetMultimap<K, V> {
    */
   @CanIgnoreReturnValue
   @Override
-  SortedSet<V> removeAll(@NullableDecl Object key);
+  SortedSet<V> removeAll(@CheckForNull Object key);
 
   /**
    * Stores a collection of values with the same key, replacing any existing values for that key.
@@ -83,7 +89,7 @@ public interface SortedSetMultimap<K, V> extends SetMultimap<K, V> {
    */
   @CanIgnoreReturnValue
   @Override
-  SortedSet<V> replaceValues(K key, Iterable<? extends V> values);
+  SortedSet<V> replaceValues(@ParametricNullness K key, Iterable<? extends V> values);
 
   /**
    * Returns a map view that associates each key with the corresponding values in the multimap.
@@ -109,5 +115,6 @@ public interface SortedSetMultimap<K, V> extends SetMultimap<K, V> {
    * Returns the comparator that orders the multimap values, with {@code null} indicating that
    * natural ordering is used.
    */
+  @CheckForNull
   Comparator<? super V> valueComparator();
 }
diff --git a/android/guava/src/com/google/common/collect/SparseImmutableTable.java b/android/guava/src/com/google/common/collect/SparseImmutableTable.java
index a7fe85debd1c..44881fde7f73 100644
--- a/android/guava/src/com/google/common/collect/SparseImmutableTable.java
+++ b/android/guava/src/com/google/common/collect/SparseImmutableTable.java
@@ -14,6 +14,8 @@
 
 package com.google.common.collect;
 
+import static java.util.Objects.requireNonNull;
+
 import com.google.common.annotations.GwtCompatible;
 import com.google.errorprone.annotations.Immutable;
 import java.util.LinkedHashMap;
@@ -23,6 +25,7 @@
 /** A {@code RegularImmutableTable} optimized for sparse data. */
 @GwtCompatible
 @Immutable(containerOf = {"R", "C", "V"})
+@ElementTypesAreNonnullByDefault
 final class SparseImmutableTable<R, C, V> extends RegularImmutableTable<R, C, V> {
   static final ImmutableTable<Object, Object, Object> EMPTY =
       new SparseImmutableTable<>(
@@ -61,12 +64,16 @@ final class SparseImmutableTable<R, C, V> extends RegularImmutableTable<R, C, V>
       C columnKey = cell.getColumnKey();
       V value = cell.getValue();
 
-      cellRowIndices[i] = rowIndex.get(rowKey);
-      Map<C, V> thisRow = rows.get(rowKey);
+      /*
+       * These requireNonNull calls are safe because we construct the maps to hold all the provided
+       * cells.
+       */
+      cellRowIndices[i] = requireNonNull(rowIndex.get(rowKey));
+      Map<C, V> thisRow = requireNonNull(rows.get(rowKey));
       cellColumnInRowIndices[i] = thisRow.size();
       V oldValue = thisRow.put(columnKey, value);
       checkNoDuplicate(rowKey, columnKey, oldValue, value);
-      columns.get(columnKey).put(rowKey, value);
+      requireNonNull(columns.get(columnKey)).put(rowKey, value);
     }
     this.cellRowIndices = cellRowIndices;
     this.cellColumnInRowIndices = cellColumnInRowIndices;
@@ -75,14 +82,14 @@ final class SparseImmutableTable<R, C, V> extends RegularImmutableTable<R, C, V>
     for (Entry<R, Map<C, V>> row : rows.entrySet()) {
       rowBuilder.put(row.getKey(), ImmutableMap.copyOf(row.getValue()));
     }
-    this.rowMap = rowBuilder.build();
+    this.rowMap = rowBuilder.buildOrThrow();
 
     ImmutableMap.Builder<C, ImmutableMap<R, V>> columnBuilder =
         new ImmutableMap.Builder<>(columns.size());
     for (Entry<C, Map<R, V>> col : columns.entrySet()) {
       columnBuilder.put(col.getKey(), ImmutableMap.copyOf(col.getValue()));
     }
-    this.columnMap = columnBuilder.build();
+    this.columnMap = columnBuilder.buildOrThrow();
   }
 
   @Override
@@ -128,7 +135,8 @@ SerializedForm createSerializedForm() {
     int[] cellColumnIndices = new int[cellSet().size()];
     int i = 0;
     for (Cell<R, C, V> cell : cellSet()) {
-      cellColumnIndices[i++] = columnKeyToIndex.get(cell.getColumnKey());
+      // requireNonNull is safe because the cell exists in the table.
+      cellColumnIndices[i++] = requireNonNull(columnKeyToIndex.get(cell.getColumnKey()));
     }
     return SerializedForm.create(this, cellRowIndices, cellColumnIndices);
   }
diff --git a/android/guava/src/com/google/common/collect/StandardRowSortedTable.java b/android/guava/src/com/google/common/collect/StandardRowSortedTable.java
index 19a14c38533f..bea5b7bb3a86 100644
--- a/android/guava/src/com/google/common/collect/StandardRowSortedTable.java
+++ b/android/guava/src/com/google/common/collect/StandardRowSortedTable.java
@@ -26,6 +26,7 @@
 import java.util.Set;
 import java.util.SortedMap;
 import java.util.SortedSet;
+import javax.annotation.CheckForNull;
 
 /**
  * Implementation of {@code Table} whose iteration ordering across row keys is sorted by their
@@ -45,6 +46,7 @@
  * @author Jared Levy
  */
 @GwtCompatible
+@ElementTypesAreNonnullByDefault
 class StandardRowSortedTable<R, C, V> extends StandardTable<R, C, V>
     implements RowSortedTable<R, C, V> {
   /*
@@ -102,6 +104,7 @@ SortedSet<R> createKeySet() {
     }
 
     @Override
+    @CheckForNull
     public Comparator<? super R> comparator() {
       return sortedBackingMap().comparator();
     }
diff --git a/android/guava/src/com/google/common/collect/StandardTable.java b/android/guava/src/com/google/common/collect/StandardTable.java
index efed27a3451b..4c1ffe1843a3 100644
--- a/android/guava/src/com/google/common/collect/StandardTable.java
+++ b/android/guava/src/com/google/common/collect/StandardTable.java
@@ -23,6 +23,8 @@
 import static com.google.common.base.Predicates.not;
 import static com.google.common.collect.Maps.safeContainsKey;
 import static com.google.common.collect.Maps.safeGet;
+import static com.google.common.collect.NullnessCasts.uncheckedCastNullableTToT;
+import static java.util.Objects.requireNonNull;
 
 import com.google.common.annotations.GwtCompatible;
 import com.google.common.base.Function;
@@ -40,7 +42,7 @@
 import java.util.Map;
 import java.util.Map.Entry;
 import java.util.Set;
-import org.checkerframework.checker.nullness.compatqual.NullableDecl;
+import javax.annotation.CheckForNull;
 
 /**
  * {@link Table} implementation backed by a map that associates row keys with column key / value
@@ -62,6 +64,7 @@
  * @author Jared Levy
  */
 @GwtCompatible
+@ElementTypesAreNonnullByDefault
 class StandardTable<R, C, V> extends AbstractTable<R, C, V> implements Serializable {
   @GwtTransient final Map<R, Map<C, V>> backingMap;
   @GwtTransient final Supplier<? extends Map<C, V>> factory;
@@ -74,12 +77,12 @@ class StandardTable<R, C, V> extends AbstractTable<R, C, V> implements Serializa
   // Accessors
 
   @Override
-  public boolean contains(@NullableDecl Object rowKey, @NullableDecl Object columnKey) {
+  public boolean contains(@CheckForNull Object rowKey, @CheckForNull Object columnKey) {
     return rowKey != null && columnKey != null && super.contains(rowKey, columnKey);
   }
 
   @Override
-  public boolean containsColumn(@NullableDecl Object columnKey) {
+  public boolean containsColumn(@CheckForNull Object columnKey) {
     if (columnKey == null) {
       return false;
     }
@@ -92,17 +95,18 @@ public boolean containsColumn(@NullableDecl Object columnKey) {
   }
 
   @Override
-  public boolean containsRow(@NullableDecl Object rowKey) {
+  public boolean containsRow(@CheckForNull Object rowKey) {
     return rowKey != null && safeContainsKey(backingMap, rowKey);
   }
 
   @Override
-  public boolean containsValue(@NullableDecl Object value) {
+  public boolean containsValue(@CheckForNull Object value) {
     return value != null && super.containsValue(value);
   }
 
   @Override
-  public V get(@NullableDecl Object rowKey, @NullableDecl Object columnKey) {
+  @CheckForNull
+  public V get(@CheckForNull Object rowKey, @CheckForNull Object columnKey) {
     return (rowKey == null || columnKey == null) ? null : super.get(rowKey, columnKey);
   }
 
@@ -138,6 +142,7 @@ private Map<C, V> getOrCreate(R rowKey) {
 
   @CanIgnoreReturnValue
   @Override
+  @CheckForNull
   public V put(R rowKey, C columnKey, V value) {
     checkNotNull(rowKey);
     checkNotNull(columnKey);
@@ -147,7 +152,8 @@ public V put(R rowKey, C columnKey, V value) {
 
   @CanIgnoreReturnValue
   @Override
-  public V remove(@NullableDecl Object rowKey, @NullableDecl Object columnKey) {
+  @CheckForNull
+  public V remove(@CheckForNull Object rowKey, @CheckForNull Object columnKey) {
     if ((rowKey == null) || (columnKey == null)) {
       return null;
     }
@@ -163,7 +169,7 @@ public V remove(@NullableDecl Object rowKey, @NullableDecl Object columnKey) {
   }
 
   @CanIgnoreReturnValue
-  private Map<R, V> removeColumn(Object column) {
+  private Map<R, V> removeColumn(@CheckForNull Object column) {
     Map<R, V> output = new LinkedHashMap<>();
     Iterator<Entry<R, Map<C, V>>> iterator = backingMap.entrySet().iterator();
     while (iterator.hasNext()) {
@@ -179,12 +185,14 @@ private Map<R, V> removeColumn(Object column) {
     return output;
   }
 
-  private boolean containsMapping(Object rowKey, Object columnKey, Object value) {
+  private boolean containsMapping(
+      @CheckForNull Object rowKey, @CheckForNull Object columnKey, @CheckForNull Object value) {
     return value != null && value.equals(get(rowKey, columnKey));
   }
 
   /** Remove a row key / column key / value mapping, if present. */
-  private boolean removeMapping(Object rowKey, Object columnKey, Object value) {
+  private boolean removeMapping(
+      @CheckForNull Object rowKey, @CheckForNull Object columnKey, @CheckForNull Object value) {
     if (containsMapping(rowKey, columnKey, value)) {
       remove(rowKey, columnKey);
       return true;
@@ -232,7 +240,7 @@ Iterator<Cell<R, C, V>> cellIterator() {
 
   private class CellIterator implements Iterator<Cell<R, C, V>> {
     final Iterator<Entry<R, Map<C, V>>> rowIterator = backingMap.entrySet().iterator();
-    @NullableDecl Entry<R, Map<C, V>> rowEntry;
+    @CheckForNull Entry<R, Map<C, V>> rowEntry;
     Iterator<Entry<C, V>> columnIterator = Iterators.emptyModifiableIterator();
 
     @Override
@@ -246,6 +254,20 @@ public Cell<R, C, V> next() {
         rowEntry = rowIterator.next();
         columnIterator = rowEntry.getValue().entrySet().iterator();
       }
+      /*
+       * requireNonNull is safe because:
+       *
+       * - columnIterator started off pointing to an empty iterator, so we must have entered the
+       *   `if` body above at least once. Thus, if we got this far, that `if` body initialized
+       *   rowEntry at least once.
+       *
+       * - The only case in which rowEntry is cleared (during remove() below) happens only if the
+       *   caller removed every element from columnIterator. During that process, we would have had
+       *   to iterate it to exhaustion. Then we can apply the logic above about an empty
+       *   columnIterator. (This assumes no concurrent modification, but behavior under concurrent
+       *   modification is undefined, anyway.)
+       */
+      requireNonNull(rowEntry);
       Entry<C, V> columnEntry = columnIterator.next();
       return Tables.immutableCell(rowEntry.getKey(), columnEntry.getKey(), columnEntry.getValue());
     }
@@ -253,7 +275,17 @@ public Cell<R, C, V> next() {
     @Override
     public void remove() {
       columnIterator.remove();
-      if (rowEntry.getValue().isEmpty()) {
+      /*
+       * requireNonNull is safe because:
+       *
+       * - columnIterator.remove() succeeded, so it must have returned a value, so it must have been
+       * initialized by next() -- which initializes rowEntry, too.
+       *
+       * - rowEntry isn't cleared except below. If it was cleared below, then either
+       *   columnIterator.remove() would have failed above (if the user hasn't called next() since
+       *   then) or rowEntry would have been initialized by next() (as discussed above).
+       */
+      if (requireNonNull(rowEntry).getValue().isEmpty()) {
         rowIterator.remove();
         rowEntry = null;
       }
@@ -272,39 +304,43 @@ class Row extends IteratorBasedAbstractMap<C, V> {
       this.rowKey = checkNotNull(rowKey);
     }
 
-    @NullableDecl Map<C, V> backingRowMap;
+    @CheckForNull Map<C, V> backingRowMap;
 
-    Map<C, V> backingRowMap() {
-      return (backingRowMap == null || (backingRowMap.isEmpty() && backingMap.containsKey(rowKey)))
-          ? backingRowMap = computeBackingRowMap()
-          : backingRowMap;
+    final void updateBackingRowMapField() {
+      if (backingRowMap == null || (backingRowMap.isEmpty() && backingMap.containsKey(rowKey))) {
+        backingRowMap = computeBackingRowMap();
+      }
     }
 
+    @CheckForNull
     Map<C, V> computeBackingRowMap() {
       return backingMap.get(rowKey);
     }
 
     // Call this every time we perform a removal.
     void maintainEmptyInvariant() {
-      if (backingRowMap() != null && backingRowMap.isEmpty()) {
+      updateBackingRowMapField();
+      if (backingRowMap != null && backingRowMap.isEmpty()) {
         backingMap.remove(rowKey);
         backingRowMap = null;
       }
     }
 
     @Override
-    public boolean containsKey(Object key) {
-      Map<C, V> backingRowMap = backingRowMap();
+    public boolean containsKey(@CheckForNull Object key) {
+      updateBackingRowMapField();
       return (key != null && backingRowMap != null) && Maps.safeContainsKey(backingRowMap, key);
     }
 
     @Override
-    public V get(Object key) {
-      Map<C, V> backingRowMap = backingRowMap();
+    @CheckForNull
+    public V get(@CheckForNull Object key) {
+      updateBackingRowMapField();
       return (key != null && backingRowMap != null) ? Maps.safeGet(backingRowMap, key) : null;
     }
 
     @Override
+    @CheckForNull
     public V put(C key, V value) {
       checkNotNull(key);
       checkNotNull(value);
@@ -315,8 +351,9 @@ public V put(C key, V value) {
     }
 
     @Override
-    public V remove(Object key) {
-      Map<C, V> backingRowMap = backingRowMap();
+    @CheckForNull
+    public V remove(@CheckForNull Object key) {
+      updateBackingRowMapField();
       if (backingRowMap == null) {
         return null;
       }
@@ -327,7 +364,7 @@ public V remove(Object key) {
 
     @Override
     public void clear() {
-      Map<C, V> backingRowMap = backingRowMap();
+      updateBackingRowMapField();
       if (backingRowMap != null) {
         backingRowMap.clear();
       }
@@ -336,17 +373,17 @@ public void clear() {
 
     @Override
     public int size() {
-      Map<C, V> map = backingRowMap();
-      return (map == null) ? 0 : map.size();
+      updateBackingRowMapField();
+      return (backingRowMap == null) ? 0 : backingRowMap.size();
     }
 
     @Override
     Iterator<Entry<C, V>> entryIterator() {
-      final Map<C, V> map = backingRowMap();
-      if (map == null) {
+      updateBackingRowMapField();
+      if (backingRowMap == null) {
         return Iterators.emptyModifiableIterator();
       }
-      final Iterator<Entry<C, V>> iterator = map.entrySet().iterator();
+      final Iterator<Entry<C, V>> iterator = backingRowMap.entrySet().iterator();
       return new Iterator<Entry<C, V>>() {
         @Override
         public boolean hasNext() {
@@ -379,7 +416,7 @@ public V setValue(V value) {
         }
 
         @Override
-        public boolean equals(Object object) {
+        public boolean equals(@CheckForNull Object object) {
           // TODO(lowasser): identify why this affects GWT tests
           return standardEquals(object);
         }
@@ -405,22 +442,25 @@ private class Column extends ViewCachingAbstractMap<R, V> {
     }
 
     @Override
+    @CheckForNull
     public V put(R key, V value) {
       return StandardTable.this.put(key, columnKey, value);
     }
 
     @Override
-    public V get(Object key) {
+    @CheckForNull
+    public V get(@CheckForNull Object key) {
       return StandardTable.this.get(key, columnKey);
     }
 
     @Override
-    public boolean containsKey(Object key) {
+    public boolean containsKey(@CheckForNull Object key) {
       return StandardTable.this.contains(key, columnKey);
     }
 
     @Override
-    public V remove(Object key) {
+    @CheckForNull
+    public V remove(@CheckForNull Object key) {
       return StandardTable.this.remove(key, columnKey);
     }
 
@@ -478,7 +518,7 @@ public void clear() {
       }
 
       @Override
-      public boolean contains(Object o) {
+      public boolean contains(@CheckForNull Object o) {
         if (o instanceof Entry) {
           Entry<?, ?> entry = (Entry<?, ?>) o;
           return containsMapping(entry.getKey(), columnKey, entry.getValue());
@@ -487,7 +527,7 @@ public boolean contains(Object o) {
       }
 
       @Override
-      public boolean remove(Object obj) {
+      public boolean remove(@CheckForNull Object obj) {
         if (obj instanceof Entry) {
           Entry<?, ?> entry = (Entry<?, ?>) obj;
           return removeMapping(entry.getKey(), columnKey, entry.getValue());
@@ -505,6 +545,7 @@ private class EntrySetIterator extends AbstractIterator<Entry<R, V>> {
       final Iterator<Entry<R, Map<C, V>>> iterator = backingMap.entrySet().iterator();
 
       @Override
+      @CheckForNull
       protected Entry<R, V> computeNext() {
         while (iterator.hasNext()) {
           final Entry<R, Map<C, V>> entry = iterator.next();
@@ -523,7 +564,22 @@ public V getValue() {
 
               @Override
               public V setValue(V value) {
-                return entry.getValue().put(columnKey, checkNotNull(value));
+                /*
+                 * The cast is safe because of the containsKey check above. (Well, it's possible for
+                 * the map to change between that call and this one. But if that happens, the
+                 * behavior is undefined because of the concurrent mutation.)
+                 *
+                 * (Our prototype checker happens to be "smart" enough to understand this for the
+                 * *get* call in getValue but not for the *put* call here.)
+                 *
+                 * (Arguably we should use requireNonNull rather than uncheckedCastNullableTToT: We
+                 * know that V is a non-null type because that's the only kind of value type that
+                 * StandardTable supports. Thus, requireNonNull is safe as long as the cell is still
+                 * present. (And if it's not present, behavior is undefined.) However, that's a
+                 * behavior change relative to the old code, so it didn't seem worth risking.)
+                 */
+                return uncheckedCastNullableTToT(
+                    entry.getValue().put(columnKey, checkNotNull(value)));
               }
             }
             return new EntryImpl();
@@ -545,12 +601,12 @@ private class KeySet extends Maps.KeySet<R, V> {
       }
 
       @Override
-      public boolean contains(Object obj) {
+      public boolean contains(@CheckForNull Object obj) {
         return StandardTable.this.contains(obj, columnKey);
       }
 
       @Override
-      public boolean remove(Object obj) {
+      public boolean remove(@CheckForNull Object obj) {
         return StandardTable.this.remove(obj, columnKey) != null;
       }
 
@@ -572,7 +628,7 @@ private class Values extends Maps.Values<R, V> {
       }
 
       @Override
-      public boolean remove(Object obj) {
+      public boolean remove(@CheckForNull Object obj) {
         return obj != null && removeFromColumnIf(Maps.<V>valuePredicateOnEntries(equalTo(obj)));
       }
 
@@ -593,7 +649,7 @@ public Set<R> rowKeySet() {
     return rowMap().keySet();
   }
 
-  @NullableDecl private transient Set<C> columnKeySet;
+  @CheckForNull private transient Set<C> columnKeySet;
 
   /**
    * {@inheritDoc}
@@ -622,7 +678,7 @@ public int size() {
     }
 
     @Override
-    public boolean remove(Object obj) {
+    public boolean remove(@CheckForNull Object obj) {
       if (obj == null) {
         return false;
       }
@@ -677,7 +733,7 @@ public boolean retainAll(Collection<?> c) {
     }
 
     @Override
-    public boolean contains(Object obj) {
+    public boolean contains(@CheckForNull Object obj) {
       return containsColumn(obj);
     }
   }
@@ -695,6 +751,7 @@ private class ColumnKeyIterator extends AbstractIterator<C> {
     Iterator<Entry<C, V>> entryIterator = Iterators.emptyIterator();
 
     @Override
+    @CheckForNull
     protected C computeNext() {
       while (true) {
         if (entryIterator.hasNext()) {
@@ -723,7 +780,7 @@ public Collection<V> values() {
     return super.values();
   }
 
-  @NullableDecl private transient Map<R, Map<C, V>> rowMap;
+  @CheckForNull private transient Map<R, Map<C, V>> rowMap;
 
   @Override
   public Map<R, Map<C, V>> rowMap() {
@@ -738,19 +795,22 @@ Map<R, Map<C, V>> createRowMap() {
   @WeakOuter
   class RowMap extends ViewCachingAbstractMap<R, Map<C, V>> {
     @Override
-    public boolean containsKey(Object key) {
+    public boolean containsKey(@CheckForNull Object key) {
       return containsRow(key);
     }
 
     // performing cast only when key is in backing map and has the correct type
     @SuppressWarnings("unchecked")
     @Override
-    public Map<C, V> get(Object key) {
-      return containsRow(key) ? row((R) key) : null;
+    @CheckForNull
+    public Map<C, V> get(@CheckForNull Object key) {
+      // requireNonNull is safe because of the containsRow check.
+      return containsRow(key) ? row((R) requireNonNull(key)) : null;
     }
 
     @Override
-    public Map<C, V> remove(Object key) {
+    @CheckForNull
+    public Map<C, V> remove(@CheckForNull Object key) {
       return (key == null) ? null : backingMap.remove(key);
     }
 
@@ -779,7 +839,7 @@ public int size() {
       }
 
       @Override
-      public boolean contains(Object obj) {
+      public boolean contains(@CheckForNull Object obj) {
         if (obj instanceof Entry) {
           Entry<?, ?> entry = (Entry<?, ?>) obj;
           return entry.getKey() != null
@@ -790,7 +850,7 @@ public boolean contains(Object obj) {
       }
 
       @Override
-      public boolean remove(Object obj) {
+      public boolean remove(@CheckForNull Object obj) {
         if (obj instanceof Entry) {
           Entry<?, ?> entry = (Entry<?, ?>) obj;
           return entry.getKey() != null
@@ -802,7 +862,7 @@ public boolean remove(Object obj) {
     }
   }
 
-  @NullableDecl private transient ColumnMap columnMap;
+  @CheckForNull private transient ColumnMap columnMap;
 
   @Override
   public Map<C, Map<R, V>> columnMap() {
@@ -816,17 +876,20 @@ private class ColumnMap extends ViewCachingAbstractMap<C, Map<R, V>> {
     // has the correct type.
     @SuppressWarnings("unchecked")
     @Override
-    public Map<R, V> get(Object key) {
-      return containsColumn(key) ? column((C) key) : null;
+    @CheckForNull
+    public Map<R, V> get(@CheckForNull Object key) {
+      // requireNonNull is safe because of the containsColumn check.
+      return containsColumn(key) ? column((C) requireNonNull(key)) : null;
     }
 
     @Override
-    public boolean containsKey(Object key) {
+    public boolean containsKey(@CheckForNull Object key) {
       return containsColumn(key);
     }
 
     @Override
-    public Map<R, V> remove(Object key) {
+    @CheckForNull
+    public Map<R, V> remove(@CheckForNull Object key) {
       return containsColumn(key) ? removeColumn(key) : null;
     }
 
@@ -865,23 +928,24 @@ public int size() {
       }
 
       @Override
-      public boolean contains(Object obj) {
+      public boolean contains(@CheckForNull Object obj) {
         if (obj instanceof Entry) {
           Entry<?, ?> entry = (Entry<?, ?>) obj;
           if (containsColumn(entry.getKey())) {
-            // The cast to C occurs only when the key is in the map, implying
-            // that it has the correct type.
-            @SuppressWarnings("unchecked")
-            C columnKey = (C) entry.getKey();
-            return get(columnKey).equals(entry.getValue());
+            // requireNonNull is safe because of the containsColumn check.
+            return requireNonNull(get(entry.getKey())).equals(entry.getValue());
           }
         }
         return false;
       }
 
       @Override
-      public boolean remove(Object obj) {
-        if (contains(obj)) {
+      public boolean remove(@CheckForNull Object obj) {
+        /*
+         * `o instanceof Entry` is guaranteed by `contains`, but we check it here to satisfy our
+         * nullness checker.
+         */
+        if (contains(obj) && obj instanceof Entry) {
           Entry<?, ?> entry = (Entry<?, ?>) obj;
           removeColumn(entry.getKey());
           return true;
@@ -922,7 +986,7 @@ private class ColumnMapValues extends Maps.Values<C, Map<R, V>> {
       }
 
       @Override
-      public boolean remove(Object obj) {
+      public boolean remove(@CheckForNull Object obj) {
         for (Entry<C, Map<R, V>> entry : ColumnMap.this.entrySet()) {
           if (entry.getValue().equals(obj)) {
             removeColumn(entry.getKey());
diff --git a/android/guava/src/com/google/common/collect/Synchronized.java b/android/guava/src/com/google/common/collect/Synchronized.java
index c4cdb1795f84..42bf6114c840 100644
--- a/android/guava/src/com/google/common/collect/Synchronized.java
+++ b/android/guava/src/com/google/common/collect/Synchronized.java
@@ -32,7 +32,6 @@
 import java.util.List;
 import java.util.ListIterator;
 import java.util.Map;
-import java.util.Map.Entry;
 import java.util.NavigableMap;
 import java.util.NavigableSet;
 import java.util.Queue;
@@ -40,7 +39,8 @@
 import java.util.Set;
 import java.util.SortedMap;
 import java.util.SortedSet;
-import org.checkerframework.checker.nullness.compatqual.NullableDecl;
+import javax.annotation.CheckForNull;
+import org.checkerframework.checker.nullness.qual.Nullable;
 
 /**
  * Synchronized collection views. The returned synchronized collection views are serializable if the
@@ -55,6 +55,16 @@
  * @author Jared Levy
  */
 @GwtCompatible(emulated = true)
+@ElementTypesAreNonnullByDefault
+/*
+ * I have decided not to bother adding @ParametricNullness annotations in this class. Adding them is
+ * a lot of busy work, and the annotation matters only when the APIs to be annotated are visible to
+ * Kotlin code. In this class, nothing is publicly visible (nor exposed indirectly through a
+ * publicly visible subclass), and I doubt any of our current or future Kotlin extensions for the
+ * package will refer to the class. Plus, @ParametricNullness is only a temporary workaround,
+ * anyway, so we just need to get by without the annotations here until Kotlin better understands
+ * our other nullness annotations.
+ */
 final class Synchronized {
   private Synchronized() {}
 
@@ -62,7 +72,7 @@ static class SynchronizedObject implements Serializable {
     final Object delegate;
     final Object mutex;
 
-    SynchronizedObject(Object delegate, @NullableDecl Object mutex) {
+    SynchronizedObject(Object delegate, @CheckForNull Object mutex) {
       this.delegate = checkNotNull(delegate);
       this.mutex = (mutex == null) ? this : mutex;
     }
@@ -96,14 +106,15 @@ private void writeObject(ObjectOutputStream stream) throws IOException {
     private static final long serialVersionUID = 0;
   }
 
-  private static <E> Collection<E> collection(
-      Collection<E> collection, @NullableDecl Object mutex) {
+  private static <E extends @Nullable Object> Collection<E> collection(
+      Collection<E> collection, @CheckForNull Object mutex) {
     return new SynchronizedCollection<E>(collection, mutex);
   }
 
   @VisibleForTesting
-  static class SynchronizedCollection<E> extends SynchronizedObject implements Collection<E> {
-    private SynchronizedCollection(Collection<E> delegate, @NullableDecl Object mutex) {
+  static class SynchronizedCollection<E extends @Nullable Object> extends SynchronizedObject
+      implements Collection<E> {
+    private SynchronizedCollection(Collection<E> delegate, @CheckForNull Object mutex) {
       super(delegate, mutex);
     }
 
@@ -135,7 +146,7 @@ public void clear() {
     }
 
     @Override
-    public boolean contains(Object o) {
+    public boolean contains(@CheckForNull Object o) {
       synchronized (mutex) {
         return delegate().contains(o);
       }
@@ -161,7 +172,7 @@ public Iterator<E> iterator() {
     }
 
     @Override
-    public boolean remove(Object o) {
+    public boolean remove(@CheckForNull Object o) {
       synchronized (mutex) {
         return delegate().remove(o);
       }
@@ -189,14 +200,15 @@ public int size() {
     }
 
     @Override
-    public Object[] toArray() {
+    public @Nullable Object[] toArray() {
       synchronized (mutex) {
         return delegate().toArray();
       }
     }
 
     @Override
-    public <T> T[] toArray(T[] a) {
+    @SuppressWarnings("nullness") // b/192354773 in our checker affects toArray declarations
+    public <T extends @Nullable Object> T[] toArray(T[] a) {
       synchronized (mutex) {
         return delegate().toArray(a);
       }
@@ -206,13 +218,14 @@ public <T> T[] toArray(T[] a) {
   }
 
   @VisibleForTesting
-  static <E> Set<E> set(Set<E> set, @NullableDecl Object mutex) {
+  static <E extends @Nullable Object> Set<E> set(Set<E> set, @CheckForNull Object mutex) {
     return new SynchronizedSet<E>(set, mutex);
   }
 
-  static class SynchronizedSet<E> extends SynchronizedCollection<E> implements Set<E> {
+  static class SynchronizedSet<E extends @Nullable Object> extends SynchronizedCollection<E>
+      implements Set<E> {
 
-    SynchronizedSet(Set<E> delegate, @NullableDecl Object mutex) {
+    SynchronizedSet(Set<E> delegate, @CheckForNull Object mutex) {
       super(delegate, mutex);
     }
 
@@ -222,7 +235,7 @@ Set<E> delegate() {
     }
 
     @Override
-    public boolean equals(Object o) {
+    public boolean equals(@CheckForNull Object o) {
       if (o == this) {
         return true;
       }
@@ -241,12 +254,14 @@ public int hashCode() {
     private static final long serialVersionUID = 0;
   }
 
-  private static <E> SortedSet<E> sortedSet(SortedSet<E> set, @NullableDecl Object mutex) {
+  private static <E extends @Nullable Object> SortedSet<E> sortedSet(
+      SortedSet<E> set, @CheckForNull Object mutex) {
     return new SynchronizedSortedSet<E>(set, mutex);
   }
 
-  static class SynchronizedSortedSet<E> extends SynchronizedSet<E> implements SortedSet<E> {
-    SynchronizedSortedSet(SortedSet<E> delegate, @NullableDecl Object mutex) {
+  static class SynchronizedSortedSet<E extends @Nullable Object> extends SynchronizedSet<E>
+      implements SortedSet<E> {
+    SynchronizedSortedSet(SortedSet<E> delegate, @CheckForNull Object mutex) {
       super(delegate, mutex);
     }
 
@@ -256,6 +271,7 @@ SortedSet<E> delegate() {
     }
 
     @Override
+    @CheckForNull
     public Comparator<? super E> comparator() {
       synchronized (mutex) {
         return delegate().comparator();
@@ -300,14 +316,16 @@ public E last() {
     private static final long serialVersionUID = 0;
   }
 
-  private static <E> List<E> list(List<E> list, @NullableDecl Object mutex) {
+  private static <E extends @Nullable Object> List<E> list(
+      List<E> list, @CheckForNull Object mutex) {
     return (list instanceof RandomAccess)
         ? new SynchronizedRandomAccessList<E>(list, mutex)
         : new SynchronizedList<E>(list, mutex);
   }
 
-  private static class SynchronizedList<E> extends SynchronizedCollection<E> implements List<E> {
-    SynchronizedList(List<E> delegate, @NullableDecl Object mutex) {
+  private static class SynchronizedList<E extends @Nullable Object>
+      extends SynchronizedCollection<E> implements List<E> {
+    SynchronizedList(List<E> delegate, @CheckForNull Object mutex) {
       super(delegate, mutex);
     }
 
@@ -338,14 +356,14 @@ public E get(int index) {
     }
 
     @Override
-    public int indexOf(Object o) {
+    public int indexOf(@CheckForNull Object o) {
       synchronized (mutex) {
         return delegate().indexOf(o);
       }
     }
 
     @Override
-    public int lastIndexOf(Object o) {
+    public int lastIndexOf(@CheckForNull Object o) {
       synchronized (mutex) {
         return delegate().lastIndexOf(o);
       }
@@ -383,7 +401,7 @@ public List<E> subList(int fromIndex, int toIndex) {
     }
 
     @Override
-    public boolean equals(Object o) {
+    public boolean equals(@CheckForNull Object o) {
       if (o == this) {
         return true;
       }
@@ -402,28 +420,29 @@ public int hashCode() {
     private static final long serialVersionUID = 0;
   }
 
-  private static class SynchronizedRandomAccessList<E> extends SynchronizedList<E>
-      implements RandomAccess {
-    SynchronizedRandomAccessList(List<E> list, @NullableDecl Object mutex) {
+  private static class SynchronizedRandomAccessList<E extends @Nullable Object>
+      extends SynchronizedList<E> implements RandomAccess {
+    SynchronizedRandomAccessList(List<E> list, @CheckForNull Object mutex) {
       super(list, mutex);
     }
 
     private static final long serialVersionUID = 0;
   }
 
-  static <E> Multiset<E> multiset(Multiset<E> multiset, @NullableDecl Object mutex) {
+  static <E extends @Nullable Object> Multiset<E> multiset(
+      Multiset<E> multiset, @CheckForNull Object mutex) {
     if (multiset instanceof SynchronizedMultiset || multiset instanceof ImmutableMultiset) {
       return multiset;
     }
     return new SynchronizedMultiset<E>(multiset, mutex);
   }
 
-  private static class SynchronizedMultiset<E> extends SynchronizedCollection<E>
-      implements Multiset<E> {
-    @NullableDecl transient Set<E> elementSet;
-    @NullableDecl transient Set<Entry<E>> entrySet;
+  private static class SynchronizedMultiset<E extends @Nullable Object>
+      extends SynchronizedCollection<E> implements Multiset<E> {
+    @CheckForNull transient Set<E> elementSet;
+    @CheckForNull transient Set<Multiset.Entry<E>> entrySet;
 
-    SynchronizedMultiset(Multiset<E> delegate, @NullableDecl Object mutex) {
+    SynchronizedMultiset(Multiset<E> delegate, @CheckForNull Object mutex) {
       super(delegate, mutex);
     }
 
@@ -433,7 +452,7 @@ Multiset<E> delegate() {
     }
 
     @Override
-    public int count(Object o) {
+    public int count(@CheckForNull Object o) {
       synchronized (mutex) {
         return delegate().count(o);
       }
@@ -447,7 +466,7 @@ public int add(E e, int n) {
     }
 
     @Override
-    public int remove(Object o, int n) {
+    public int remove(@CheckForNull Object o, int n) {
       synchronized (mutex) {
         return delegate().remove(o, n);
       }
@@ -478,7 +497,7 @@ public Set<E> elementSet() {
     }
 
     @Override
-    public Set<Entry<E>> entrySet() {
+    public Set<Multiset.Entry<E>> entrySet() {
       synchronized (mutex) {
         if (entrySet == null) {
           entrySet = typePreservingSet(delegate().entrySet(), mutex);
@@ -488,7 +507,7 @@ public Set<Entry<E>> entrySet() {
     }
 
     @Override
-    public boolean equals(Object o) {
+    public boolean equals(@CheckForNull Object o) {
       if (o == this) {
         return true;
       }
@@ -507,20 +526,21 @@ public int hashCode() {
     private static final long serialVersionUID = 0;
   }
 
-  static <K, V> Multimap<K, V> multimap(Multimap<K, V> multimap, @NullableDecl Object mutex) {
+  static <K extends @Nullable Object, V extends @Nullable Object> Multimap<K, V> multimap(
+      Multimap<K, V> multimap, @CheckForNull Object mutex) {
     if (multimap instanceof SynchronizedMultimap || multimap instanceof BaseImmutableMultimap) {
       return multimap;
     }
     return new SynchronizedMultimap<>(multimap, mutex);
   }
 
-  private static class SynchronizedMultimap<K, V> extends SynchronizedObject
-      implements Multimap<K, V> {
-    @NullableDecl transient Set<K> keySet;
-    @NullableDecl transient Collection<V> valuesCollection;
-    @NullableDecl transient Collection<Entry<K, V>> entries;
-    @NullableDecl transient Map<K, Collection<V>> asMap;
-    @NullableDecl transient Multiset<K> keys;
+  private static class SynchronizedMultimap<K extends @Nullable Object, V extends @Nullable Object>
+      extends SynchronizedObject implements Multimap<K, V> {
+    @CheckForNull transient Set<K> keySet;
+    @CheckForNull transient Collection<V> valuesCollection;
+    @CheckForNull transient Collection<Map.Entry<K, V>> entries;
+    @CheckForNull transient Map<K, Collection<V>> asMap;
+    @CheckForNull transient Multiset<K> keys;
 
     @SuppressWarnings("unchecked")
     @Override
@@ -528,7 +548,7 @@ Multimap<K, V> delegate() {
       return (Multimap<K, V>) super.delegate();
     }
 
-    SynchronizedMultimap(Multimap<K, V> delegate, @NullableDecl Object mutex) {
+    SynchronizedMultimap(Multimap<K, V> delegate, @CheckForNull Object mutex) {
       super(delegate, mutex);
     }
 
@@ -547,21 +567,21 @@ public boolean isEmpty() {
     }
 
     @Override
-    public boolean containsKey(Object key) {
+    public boolean containsKey(@CheckForNull Object key) {
       synchronized (mutex) {
         return delegate().containsKey(key);
       }
     }
 
     @Override
-    public boolean containsValue(Object value) {
+    public boolean containsValue(@CheckForNull Object value) {
       synchronized (mutex) {
         return delegate().containsValue(value);
       }
     }
 
     @Override
-    public boolean containsEntry(Object key, Object value) {
+    public boolean containsEntry(@CheckForNull Object key, @CheckForNull Object value) {
       synchronized (mutex) {
         return delegate().containsEntry(key, value);
       }
@@ -603,14 +623,14 @@ public Collection<V> replaceValues(K key, Iterable<? extends V> values) {
     }
 
     @Override
-    public boolean remove(Object key, Object value) {
+    public boolean remove(@CheckForNull Object key, @CheckForNull Object value) {
       synchronized (mutex) {
         return delegate().remove(key, value);
       }
     }
 
     @Override
-    public Collection<V> removeAll(Object key) {
+    public Collection<V> removeAll(@CheckForNull Object key) {
       synchronized (mutex) {
         return delegate().removeAll(key); // copy not synchronized
       }
@@ -644,7 +664,7 @@ public Collection<V> values() {
     }
 
     @Override
-    public Collection<Entry<K, V>> entries() {
+    public Collection<Map.Entry<K, V>> entries() {
       synchronized (mutex) {
         if (entries == null) {
           entries = typePreservingCollection(delegate().entries(), mutex);
@@ -674,7 +694,7 @@ public Multiset<K> keys() {
     }
 
     @Override
-    public boolean equals(Object o) {
+    public boolean equals(@CheckForNull Object o) {
       if (o == this) {
         return true;
       }
@@ -693,17 +713,18 @@ public int hashCode() {
     private static final long serialVersionUID = 0;
   }
 
-  static <K, V> ListMultimap<K, V> listMultimap(
-      ListMultimap<K, V> multimap, @NullableDecl Object mutex) {
+  static <K extends @Nullable Object, V extends @Nullable Object> ListMultimap<K, V> listMultimap(
+      ListMultimap<K, V> multimap, @CheckForNull Object mutex) {
     if (multimap instanceof SynchronizedListMultimap || multimap instanceof BaseImmutableMultimap) {
       return multimap;
     }
     return new SynchronizedListMultimap<>(multimap, mutex);
   }
 
-  private static class SynchronizedListMultimap<K, V> extends SynchronizedMultimap<K, V>
-      implements ListMultimap<K, V> {
-    SynchronizedListMultimap(ListMultimap<K, V> delegate, @NullableDecl Object mutex) {
+  private static class SynchronizedListMultimap<
+          K extends @Nullable Object, V extends @Nullable Object>
+      extends SynchronizedMultimap<K, V> implements ListMultimap<K, V> {
+    SynchronizedListMultimap(ListMultimap<K, V> delegate, @CheckForNull Object mutex) {
       super(delegate, mutex);
     }
 
@@ -720,7 +741,7 @@ public List<V> get(K key) {
     }
 
     @Override
-    public List<V> removeAll(Object key) {
+    public List<V> removeAll(@CheckForNull Object key) {
       synchronized (mutex) {
         return delegate().removeAll(key); // copy not synchronized
       }
@@ -736,19 +757,20 @@ public List<V> replaceValues(K key, Iterable<? extends V> values) {
     private static final long serialVersionUID = 0;
   }
 
-  static <K, V> SetMultimap<K, V> setMultimap(
-      SetMultimap<K, V> multimap, @NullableDecl Object mutex) {
+  static <K extends @Nullable Object, V extends @Nullable Object> SetMultimap<K, V> setMultimap(
+      SetMultimap<K, V> multimap, @CheckForNull Object mutex) {
     if (multimap instanceof SynchronizedSetMultimap || multimap instanceof BaseImmutableMultimap) {
       return multimap;
     }
     return new SynchronizedSetMultimap<>(multimap, mutex);
   }
 
-  private static class SynchronizedSetMultimap<K, V> extends SynchronizedMultimap<K, V>
-      implements SetMultimap<K, V> {
-    @NullableDecl transient Set<Entry<K, V>> entrySet;
+  private static class SynchronizedSetMultimap<
+          K extends @Nullable Object, V extends @Nullable Object>
+      extends SynchronizedMultimap<K, V> implements SetMultimap<K, V> {
+    @CheckForNull transient Set<Map.Entry<K, V>> entrySet;
 
-    SynchronizedSetMultimap(SetMultimap<K, V> delegate, @NullableDecl Object mutex) {
+    SynchronizedSetMultimap(SetMultimap<K, V> delegate, @CheckForNull Object mutex) {
       super(delegate, mutex);
     }
 
@@ -765,7 +787,7 @@ public Set<V> get(K key) {
     }
 
     @Override
-    public Set<V> removeAll(Object key) {
+    public Set<V> removeAll(@CheckForNull Object key) {
       synchronized (mutex) {
         return delegate().removeAll(key); // copy not synchronized
       }
@@ -779,7 +801,7 @@ public Set<V> replaceValues(K key, Iterable<? extends V> values) {
     }
 
     @Override
-    public Set<Entry<K, V>> entries() {
+    public Set<Map.Entry<K, V>> entries() {
       synchronized (mutex) {
         if (entrySet == null) {
           entrySet = set(delegate().entries(), mutex);
@@ -791,17 +813,19 @@ public Set<Entry<K, V>> entries() {
     private static final long serialVersionUID = 0;
   }
 
-  static <K, V> SortedSetMultimap<K, V> sortedSetMultimap(
-      SortedSetMultimap<K, V> multimap, @NullableDecl Object mutex) {
+  static <K extends @Nullable Object, V extends @Nullable Object>
+      SortedSetMultimap<K, V> sortedSetMultimap(
+          SortedSetMultimap<K, V> multimap, @CheckForNull Object mutex) {
     if (multimap instanceof SynchronizedSortedSetMultimap) {
       return multimap;
     }
     return new SynchronizedSortedSetMultimap<>(multimap, mutex);
   }
 
-  private static class SynchronizedSortedSetMultimap<K, V> extends SynchronizedSetMultimap<K, V>
-      implements SortedSetMultimap<K, V> {
-    SynchronizedSortedSetMultimap(SortedSetMultimap<K, V> delegate, @NullableDecl Object mutex) {
+  private static class SynchronizedSortedSetMultimap<
+          K extends @Nullable Object, V extends @Nullable Object>
+      extends SynchronizedSetMultimap<K, V> implements SortedSetMultimap<K, V> {
+    SynchronizedSortedSetMultimap(SortedSetMultimap<K, V> delegate, @CheckForNull Object mutex) {
       super(delegate, mutex);
     }
 
@@ -818,7 +842,7 @@ public SortedSet<V> get(K key) {
     }
 
     @Override
-    public SortedSet<V> removeAll(Object key) {
+    public SortedSet<V> removeAll(@CheckForNull Object key) {
       synchronized (mutex) {
         return delegate().removeAll(key); // copy not synchronized
       }
@@ -832,6 +856,7 @@ public SortedSet<V> replaceValues(K key, Iterable<? extends V> values) {
     }
 
     @Override
+    @CheckForNull
     public Comparator<? super V> valueComparator() {
       synchronized (mutex) {
         return delegate().valueComparator();
@@ -841,8 +866,8 @@ public Comparator<? super V> valueComparator() {
     private static final long serialVersionUID = 0;
   }
 
-  private static <E> Collection<E> typePreservingCollection(
-      Collection<E> collection, @NullableDecl Object mutex) {
+  private static <E extends @Nullable Object> Collection<E> typePreservingCollection(
+      Collection<E> collection, @CheckForNull Object mutex) {
     if (collection instanceof SortedSet) {
       return sortedSet((SortedSet<E>) collection, mutex);
     }
@@ -855,7 +880,8 @@ private static <E> Collection<E> typePreservingCollection(
     return collection(collection, mutex);
   }
 
-  private static <E> Set<E> typePreservingSet(Set<E> set, @NullableDecl Object mutex) {
+  private static <E extends @Nullable Object> Set<E> typePreservingSet(
+      Set<E> set, @CheckForNull Object mutex) {
     if (set instanceof SortedSet) {
       return sortedSet((SortedSet<E>) set, mutex);
     } else {
@@ -863,22 +889,24 @@ private static <E> Set<E> typePreservingSet(Set<E> set, @NullableDecl Object mut
     }
   }
 
-  private static class SynchronizedAsMapEntries<K, V>
-      extends SynchronizedSet<Entry<K, Collection<V>>> {
-    SynchronizedAsMapEntries(Set<Entry<K, Collection<V>>> delegate, @NullableDecl Object mutex) {
+  private static class SynchronizedAsMapEntries<
+          K extends @Nullable Object, V extends @Nullable Object>
+      extends SynchronizedSet<Map.Entry<K, Collection<V>>> {
+    SynchronizedAsMapEntries(
+        Set<Map.Entry<K, Collection<V>>> delegate, @CheckForNull Object mutex) {
       super(delegate, mutex);
     }
 
     @Override
-    public Iterator<Entry<K, Collection<V>>> iterator() {
+    public Iterator<Map.Entry<K, Collection<V>>> iterator() {
       // Must be manually synchronized.
-      return new TransformedIterator<Entry<K, Collection<V>>, Entry<K, Collection<V>>>(
+      return new TransformedIterator<Map.Entry<K, Collection<V>>, Map.Entry<K, Collection<V>>>(
           super.iterator()) {
         @Override
-        Entry<K, Collection<V>> transform(final Entry<K, Collection<V>> entry) {
+        Map.Entry<K, Collection<V>> transform(final Map.Entry<K, Collection<V>> entry) {
           return new ForwardingMapEntry<K, Collection<V>>() {
             @Override
-            protected Entry<K, Collection<V>> delegate() {
+            protected Map.Entry<K, Collection<V>> delegate() {
               return entry;
             }
 
@@ -896,19 +924,27 @@ public Collection<V> getValue() {
     @Override
     public Object[] toArray() {
       synchronized (mutex) {
-        return ObjectArrays.toArrayImpl(delegate());
+        /*
+         * toArrayImpl returns `@Nullable Object[]` rather than `Object[]` but only because it can
+         * be used with collections that may contain null. This collection never contains nulls, so
+         * we can treat it as a plain `Object[]`.
+         */
+        @SuppressWarnings("nullness")
+        Object[] result = (Object[]) ObjectArrays.toArrayImpl(delegate());
+        return result;
       }
     }
 
     @Override
-    public <T> T[] toArray(T[] array) {
+    @SuppressWarnings("nullness") // b/192354773 in our checker affects toArray declarations
+    public <T extends @Nullable Object> T[] toArray(T[] array) {
       synchronized (mutex) {
         return ObjectArrays.toArrayImpl(delegate(), array);
       }
     }
 
     @Override
-    public boolean contains(Object o) {
+    public boolean contains(@CheckForNull Object o) {
       synchronized (mutex) {
         return Maps.containsEntryImpl(delegate(), o);
       }
@@ -922,7 +958,7 @@ public boolean containsAll(Collection<?> c) {
     }
 
     @Override
-    public boolean equals(Object o) {
+    public boolean equals(@CheckForNull Object o) {
       if (o == this) {
         return true;
       }
@@ -932,7 +968,7 @@ public boolean equals(Object o) {
     }
 
     @Override
-    public boolean remove(Object o) {
+    public boolean remove(@CheckForNull Object o) {
       synchronized (mutex) {
         return Maps.removeEntryImpl(delegate(), o);
       }
@@ -956,16 +992,18 @@ public boolean retainAll(Collection<?> c) {
   }
 
   @VisibleForTesting
-  static <K, V> Map<K, V> map(Map<K, V> map, @NullableDecl Object mutex) {
+  static <K extends @Nullable Object, V extends @Nullable Object> Map<K, V> map(
+      Map<K, V> map, @CheckForNull Object mutex) {
     return new SynchronizedMap<>(map, mutex);
   }
 
-  private static class SynchronizedMap<K, V> extends SynchronizedObject implements Map<K, V> {
-    @NullableDecl transient Set<K> keySet;
-    @NullableDecl transient Collection<V> values;
-    @NullableDecl transient Set<Entry<K, V>> entrySet;
+  private static class SynchronizedMap<K extends @Nullable Object, V extends @Nullable Object>
+      extends SynchronizedObject implements Map<K, V> {
+    @CheckForNull transient Set<K> keySet;
+    @CheckForNull transient Collection<V> values;
+    @CheckForNull transient Set<Map.Entry<K, V>> entrySet;
 
-    SynchronizedMap(Map<K, V> delegate, @NullableDecl Object mutex) {
+    SynchronizedMap(Map<K, V> delegate, @CheckForNull Object mutex) {
       super(delegate, mutex);
     }
 
@@ -983,21 +1021,21 @@ public void clear() {
     }
 
     @Override
-    public boolean containsKey(Object key) {
+    public boolean containsKey(@CheckForNull Object key) {
       synchronized (mutex) {
         return delegate().containsKey(key);
       }
     }
 
     @Override
-    public boolean containsValue(Object value) {
+    public boolean containsValue(@CheckForNull Object value) {
       synchronized (mutex) {
         return delegate().containsValue(value);
       }
     }
 
     @Override
-    public Set<Entry<K, V>> entrySet() {
+    public Set<Map.Entry<K, V>> entrySet() {
       synchronized (mutex) {
         if (entrySet == null) {
           entrySet = set(delegate().entrySet(), mutex);
@@ -1007,7 +1045,8 @@ public Set<Entry<K, V>> entrySet() {
     }
 
     @Override
-    public V get(Object key) {
+    @CheckForNull
+    public V get(@CheckForNull Object key) {
       synchronized (mutex) {
         return delegate().get(key);
       }
@@ -1031,6 +1070,7 @@ public Set<K> keySet() {
     }
 
     @Override
+    @CheckForNull
     public V put(K key, V value) {
       synchronized (mutex) {
         return delegate().put(key, value);
@@ -1045,7 +1085,8 @@ public void putAll(Map<? extends K, ? extends V> map) {
     }
 
     @Override
-    public V remove(Object key) {
+    @CheckForNull
+    public V remove(@CheckForNull Object key) {
       synchronized (mutex) {
         return delegate().remove(key);
       }
@@ -1069,7 +1110,7 @@ public Collection<V> values() {
     }
 
     @Override
-    public boolean equals(Object o) {
+    public boolean equals(@CheckForNull Object o) {
       if (o == this) {
         return true;
       }
@@ -1088,14 +1129,15 @@ public int hashCode() {
     private static final long serialVersionUID = 0;
   }
 
-  static <K, V> SortedMap<K, V> sortedMap(SortedMap<K, V> sortedMap, @NullableDecl Object mutex) {
+  static <K extends @Nullable Object, V extends @Nullable Object> SortedMap<K, V> sortedMap(
+      SortedMap<K, V> sortedMap, @CheckForNull Object mutex) {
     return new SynchronizedSortedMap<>(sortedMap, mutex);
   }
 
-  static class SynchronizedSortedMap<K, V> extends SynchronizedMap<K, V>
-      implements SortedMap<K, V> {
+  static class SynchronizedSortedMap<K extends @Nullable Object, V extends @Nullable Object>
+      extends SynchronizedMap<K, V> implements SortedMap<K, V> {
 
-    SynchronizedSortedMap(SortedMap<K, V> delegate, @NullableDecl Object mutex) {
+    SynchronizedSortedMap(SortedMap<K, V> delegate, @CheckForNull Object mutex) {
       super(delegate, mutex);
     }
 
@@ -1105,6 +1147,7 @@ SortedMap<K, V> delegate() {
     }
 
     @Override
+    @CheckForNull
     public Comparator<? super K> comparator() {
       synchronized (mutex) {
         return delegate().comparator();
@@ -1149,7 +1192,8 @@ public SortedMap<K, V> tailMap(K fromKey) {
     private static final long serialVersionUID = 0;
   }
 
-  static <K, V> BiMap<K, V> biMap(BiMap<K, V> bimap, @NullableDecl Object mutex) {
+  static <K extends @Nullable Object, V extends @Nullable Object> BiMap<K, V> biMap(
+      BiMap<K, V> bimap, @CheckForNull Object mutex) {
     if (bimap instanceof SynchronizedBiMap || bimap instanceof ImmutableBiMap) {
       return bimap;
     }
@@ -1157,13 +1201,13 @@ static <K, V> BiMap<K, V> biMap(BiMap<K, V> bimap, @NullableDecl Object mutex) {
   }
 
   @VisibleForTesting
-  static class SynchronizedBiMap<K, V> extends SynchronizedMap<K, V>
-      implements BiMap<K, V>, Serializable {
-    @NullableDecl private transient Set<V> valueSet;
-    @RetainedWith @NullableDecl private transient BiMap<V, K> inverse;
+  static class SynchronizedBiMap<K extends @Nullable Object, V extends @Nullable Object>
+      extends SynchronizedMap<K, V> implements BiMap<K, V>, Serializable {
+    @CheckForNull private transient Set<V> valueSet;
+    @RetainedWith @CheckForNull private transient BiMap<V, K> inverse;
 
     private SynchronizedBiMap(
-        BiMap<K, V> delegate, @NullableDecl Object mutex, @NullableDecl BiMap<V, K> inverse) {
+        BiMap<K, V> delegate, @CheckForNull Object mutex, @CheckForNull BiMap<V, K> inverse) {
       super(delegate, mutex);
       this.inverse = inverse;
     }
@@ -1184,6 +1228,7 @@ public Set<V> values() {
     }
 
     @Override
+    @CheckForNull
     public V forcePut(K key, V value) {
       synchronized (mutex) {
         return delegate().forcePut(key, value);
@@ -1203,16 +1248,18 @@ public BiMap<V, K> inverse() {
     private static final long serialVersionUID = 0;
   }
 
-  private static class SynchronizedAsMap<K, V> extends SynchronizedMap<K, Collection<V>> {
-    @NullableDecl transient Set<Entry<K, Collection<V>>> asMapEntrySet;
-    @NullableDecl transient Collection<Collection<V>> asMapValues;
+  private static class SynchronizedAsMap<K extends @Nullable Object, V extends @Nullable Object>
+      extends SynchronizedMap<K, Collection<V>> {
+    @CheckForNull transient Set<Map.Entry<K, Collection<V>>> asMapEntrySet;
+    @CheckForNull transient Collection<Collection<V>> asMapValues;
 
-    SynchronizedAsMap(Map<K, Collection<V>> delegate, @NullableDecl Object mutex) {
+    SynchronizedAsMap(Map<K, Collection<V>> delegate, @CheckForNull Object mutex) {
       super(delegate, mutex);
     }
 
     @Override
-    public Collection<V> get(Object key) {
+    @CheckForNull
+    public Collection<V> get(@CheckForNull Object key) {
       synchronized (mutex) {
         Collection<V> collection = super.get(key);
         return (collection == null) ? null : typePreservingCollection(collection, mutex);
@@ -1220,7 +1267,7 @@ public Collection<V> get(Object key) {
     }
 
     @Override
-    public Set<Entry<K, Collection<V>>> entrySet() {
+    public Set<Map.Entry<K, Collection<V>>> entrySet() {
       synchronized (mutex) {
         if (asMapEntrySet == null) {
           asMapEntrySet = new SynchronizedAsMapEntries<>(delegate().entrySet(), mutex);
@@ -1240,7 +1287,7 @@ public Collection<Collection<V>> values() {
     }
 
     @Override
-    public boolean containsValue(Object o) {
+    public boolean containsValue(@CheckForNull Object o) {
       // values() and its contains() method are both synchronized.
       return values().contains(o);
     }
@@ -1248,8 +1295,9 @@ public boolean containsValue(Object o) {
     private static final long serialVersionUID = 0;
   }
 
-  private static class SynchronizedAsMapValues<V> extends SynchronizedCollection<Collection<V>> {
-    SynchronizedAsMapValues(Collection<Collection<V>> delegate, @NullableDecl Object mutex) {
+  private static class SynchronizedAsMapValues<V extends @Nullable Object>
+      extends SynchronizedCollection<Collection<V>> {
+    SynchronizedAsMapValues(Collection<Collection<V>> delegate, @CheckForNull Object mutex) {
       super(delegate, mutex);
     }
 
@@ -1269,9 +1317,9 @@ Collection<V> transform(Collection<V> from) {
 
   @GwtIncompatible // NavigableSet
   @VisibleForTesting
-  static class SynchronizedNavigableSet<E> extends SynchronizedSortedSet<E>
+  static class SynchronizedNavigableSet<E extends @Nullable Object> extends SynchronizedSortedSet<E>
       implements NavigableSet<E> {
-    SynchronizedNavigableSet(NavigableSet<E> delegate, @NullableDecl Object mutex) {
+    SynchronizedNavigableSet(NavigableSet<E> delegate, @CheckForNull Object mutex) {
       super(delegate, mutex);
     }
 
@@ -1281,6 +1329,7 @@ NavigableSet<E> delegate() {
     }
 
     @Override
+    @CheckForNull
     public E ceiling(E e) {
       synchronized (mutex) {
         return delegate().ceiling(e);
@@ -1292,7 +1341,7 @@ public Iterator<E> descendingIterator() {
       return delegate().descendingIterator(); // manually synchronized
     }
 
-    @NullableDecl transient NavigableSet<E> descendingSet;
+    @CheckForNull transient NavigableSet<E> descendingSet;
 
     @Override
     public NavigableSet<E> descendingSet() {
@@ -1307,6 +1356,7 @@ public NavigableSet<E> descendingSet() {
     }
 
     @Override
+    @CheckForNull
     public E floor(E e) {
       synchronized (mutex) {
         return delegate().floor(e);
@@ -1326,6 +1376,7 @@ public SortedSet<E> headSet(E toElement) {
     }
 
     @Override
+    @CheckForNull
     public E higher(E e) {
       synchronized (mutex) {
         return delegate().higher(e);
@@ -1333,6 +1384,7 @@ public E higher(E e) {
     }
 
     @Override
+    @CheckForNull
     public E lower(E e) {
       synchronized (mutex) {
         return delegate().lower(e);
@@ -1340,6 +1392,7 @@ public E lower(E e) {
     }
 
     @Override
+    @CheckForNull
     public E pollFirst() {
       synchronized (mutex) {
         return delegate().pollFirst();
@@ -1347,6 +1400,7 @@ public E pollFirst() {
     }
 
     @Override
+    @CheckForNull
     public E pollLast() {
       synchronized (mutex) {
         return delegate().pollLast();
@@ -1383,33 +1437,34 @@ public SortedSet<E> tailSet(E fromElement) {
   }
 
   @GwtIncompatible // NavigableSet
-  static <E> NavigableSet<E> navigableSet(
-      NavigableSet<E> navigableSet, @NullableDecl Object mutex) {
+  static <E extends @Nullable Object> NavigableSet<E> navigableSet(
+      NavigableSet<E> navigableSet, @CheckForNull Object mutex) {
     return new SynchronizedNavigableSet<E>(navigableSet, mutex);
   }
 
   @GwtIncompatible // NavigableSet
-  static <E> NavigableSet<E> navigableSet(NavigableSet<E> navigableSet) {
+  static <E extends @Nullable Object> NavigableSet<E> navigableSet(NavigableSet<E> navigableSet) {
     return navigableSet(navigableSet, null);
   }
 
   @GwtIncompatible // NavigableMap
-  static <K, V> NavigableMap<K, V> navigableMap(NavigableMap<K, V> navigableMap) {
+  static <K extends @Nullable Object, V extends @Nullable Object> NavigableMap<K, V> navigableMap(
+      NavigableMap<K, V> navigableMap) {
     return navigableMap(navigableMap, null);
   }
 
   @GwtIncompatible // NavigableMap
-  static <K, V> NavigableMap<K, V> navigableMap(
-      NavigableMap<K, V> navigableMap, @NullableDecl Object mutex) {
+  static <K extends @Nullable Object, V extends @Nullable Object> NavigableMap<K, V> navigableMap(
+      NavigableMap<K, V> navigableMap, @CheckForNull Object mutex) {
     return new SynchronizedNavigableMap<>(navigableMap, mutex);
   }
 
   @GwtIncompatible // NavigableMap
   @VisibleForTesting
-  static class SynchronizedNavigableMap<K, V> extends SynchronizedSortedMap<K, V>
-      implements NavigableMap<K, V> {
+  static class SynchronizedNavigableMap<K extends @Nullable Object, V extends @Nullable Object>
+      extends SynchronizedSortedMap<K, V> implements NavigableMap<K, V> {
 
-    SynchronizedNavigableMap(NavigableMap<K, V> delegate, @NullableDecl Object mutex) {
+    SynchronizedNavigableMap(NavigableMap<K, V> delegate, @CheckForNull Object mutex) {
       super(delegate, mutex);
     }
 
@@ -1419,20 +1474,22 @@ NavigableMap<K, V> delegate() {
     }
 
     @Override
-    public Entry<K, V> ceilingEntry(K key) {
+    @CheckForNull
+    public Map.Entry<K, V> ceilingEntry(K key) {
       synchronized (mutex) {
         return nullableSynchronizedEntry(delegate().ceilingEntry(key), mutex);
       }
     }
 
     @Override
+    @CheckForNull
     public K ceilingKey(K key) {
       synchronized (mutex) {
         return delegate().ceilingKey(key);
       }
     }
 
-    @NullableDecl transient NavigableSet<K> descendingKeySet;
+    @CheckForNull transient NavigableSet<K> descendingKeySet;
 
     @Override
     public NavigableSet<K> descendingKeySet() {
@@ -1444,7 +1501,7 @@ public NavigableSet<K> descendingKeySet() {
       }
     }
 
-    @NullableDecl transient NavigableMap<K, V> descendingMap;
+    @CheckForNull transient NavigableMap<K, V> descendingMap;
 
     @Override
     public NavigableMap<K, V> descendingMap() {
@@ -1457,20 +1514,23 @@ public NavigableMap<K, V> descendingMap() {
     }
 
     @Override
-    public Entry<K, V> firstEntry() {
+    @CheckForNull
+    public Map.Entry<K, V> firstEntry() {
       synchronized (mutex) {
         return nullableSynchronizedEntry(delegate().firstEntry(), mutex);
       }
     }
 
     @Override
-    public Entry<K, V> floorEntry(K key) {
+    @CheckForNull
+    public Map.Entry<K, V> floorEntry(K key) {
       synchronized (mutex) {
         return nullableSynchronizedEntry(delegate().floorEntry(key), mutex);
       }
     }
 
     @Override
+    @CheckForNull
     public K floorKey(K key) {
       synchronized (mutex) {
         return delegate().floorKey(key);
@@ -1490,13 +1550,15 @@ public SortedMap<K, V> headMap(K toKey) {
     }
 
     @Override
-    public Entry<K, V> higherEntry(K key) {
+    @CheckForNull
+    public Map.Entry<K, V> higherEntry(K key) {
       synchronized (mutex) {
         return nullableSynchronizedEntry(delegate().higherEntry(key), mutex);
       }
     }
 
     @Override
+    @CheckForNull
     public K higherKey(K key) {
       synchronized (mutex) {
         return delegate().higherKey(key);
@@ -1504,20 +1566,23 @@ public K higherKey(K key) {
     }
 
     @Override
-    public Entry<K, V> lastEntry() {
+    @CheckForNull
+    public Map.Entry<K, V> lastEntry() {
       synchronized (mutex) {
         return nullableSynchronizedEntry(delegate().lastEntry(), mutex);
       }
     }
 
     @Override
-    public Entry<K, V> lowerEntry(K key) {
+    @CheckForNull
+    public Map.Entry<K, V> lowerEntry(K key) {
       synchronized (mutex) {
         return nullableSynchronizedEntry(delegate().lowerEntry(key), mutex);
       }
     }
 
     @Override
+    @CheckForNull
     public K lowerKey(K key) {
       synchronized (mutex) {
         return delegate().lowerKey(key);
@@ -1529,7 +1594,7 @@ public Set<K> keySet() {
       return navigableKeySet();
     }
 
-    @NullableDecl transient NavigableSet<K> navigableKeySet;
+    @CheckForNull transient NavigableSet<K> navigableKeySet;
 
     @Override
     public NavigableSet<K> navigableKeySet() {
@@ -1542,14 +1607,16 @@ public NavigableSet<K> navigableKeySet() {
     }
 
     @Override
-    public Entry<K, V> pollFirstEntry() {
+    @CheckForNull
+    public Map.Entry<K, V> pollFirstEntry() {
       synchronized (mutex) {
         return nullableSynchronizedEntry(delegate().pollFirstEntry(), mutex);
       }
     }
 
     @Override
-    public Entry<K, V> pollLastEntry() {
+    @CheckForNull
+    public Map.Entry<K, V> pollLastEntry() {
       synchronized (mutex) {
         return nullableSynchronizedEntry(delegate().pollLastEntry(), mutex);
       }
@@ -1584,8 +1651,10 @@ public SortedMap<K, V> tailMap(K fromKey) {
   }
 
   @GwtIncompatible // works but is needed only for NavigableMap
-  private static <K, V> Entry<K, V> nullableSynchronizedEntry(
-      @NullableDecl Entry<K, V> entry, @NullableDecl Object mutex) {
+  @CheckForNull
+  private static <K extends @Nullable Object, V extends @Nullable Object>
+      Map.Entry<K, V> nullableSynchronizedEntry(
+          @CheckForNull Map.Entry<K, V> entry, @CheckForNull Object mutex) {
     if (entry == null) {
       return null;
     }
@@ -1593,20 +1662,21 @@ private static <K, V> Entry<K, V> nullableSynchronizedEntry(
   }
 
   @GwtIncompatible // works but is needed only for NavigableMap
-  private static class SynchronizedEntry<K, V> extends SynchronizedObject implements Entry<K, V> {
+  private static class SynchronizedEntry<K extends @Nullable Object, V extends @Nullable Object>
+      extends SynchronizedObject implements Map.Entry<K, V> {
 
-    SynchronizedEntry(Entry<K, V> delegate, @NullableDecl Object mutex) {
+    SynchronizedEntry(Map.Entry<K, V> delegate, @CheckForNull Object mutex) {
       super(delegate, mutex);
     }
 
     @SuppressWarnings("unchecked") // guaranteed by the constructor
     @Override
-    Entry<K, V> delegate() {
-      return (Entry<K, V>) super.delegate();
+    Map.Entry<K, V> delegate() {
+      return (Map.Entry<K, V>) super.delegate();
     }
 
     @Override
-    public boolean equals(Object obj) {
+    public boolean equals(@CheckForNull Object obj) {
       synchronized (mutex) {
         return delegate().equals(obj);
       }
@@ -1643,13 +1713,14 @@ public V setValue(V value) {
     private static final long serialVersionUID = 0;
   }
 
-  static <E> Queue<E> queue(Queue<E> queue, @NullableDecl Object mutex) {
+  static <E extends @Nullable Object> Queue<E> queue(Queue<E> queue, @CheckForNull Object mutex) {
     return (queue instanceof SynchronizedQueue) ? queue : new SynchronizedQueue<E>(queue, mutex);
   }
 
-  private static class SynchronizedQueue<E> extends SynchronizedCollection<E> implements Queue<E> {
+  private static class SynchronizedQueue<E extends @Nullable Object>
+      extends SynchronizedCollection<E> implements Queue<E> {
 
-    SynchronizedQueue(Queue<E> delegate, @NullableDecl Object mutex) {
+    SynchronizedQueue(Queue<E> delegate, @CheckForNull Object mutex) {
       super(delegate, mutex);
     }
 
@@ -1673,6 +1744,7 @@ public boolean offer(E e) {
     }
 
     @Override
+    @CheckForNull
     public E peek() {
       synchronized (mutex) {
         return delegate().peek();
@@ -1680,6 +1752,7 @@ public E peek() {
     }
 
     @Override
+    @CheckForNull
     public E poll() {
       synchronized (mutex) {
         return delegate().poll();
@@ -1696,13 +1769,14 @@ public E remove() {
     private static final long serialVersionUID = 0;
   }
 
-  static <E> Deque<E> deque(Deque<E> deque, @NullableDecl Object mutex) {
+  static <E extends @Nullable Object> Deque<E> deque(Deque<E> deque, @CheckForNull Object mutex) {
     return new SynchronizedDeque<E>(deque, mutex);
   }
 
-  private static final class SynchronizedDeque<E> extends SynchronizedQueue<E> implements Deque<E> {
+  private static final class SynchronizedDeque<E extends @Nullable Object>
+      extends SynchronizedQueue<E> implements Deque<E> {
 
-    SynchronizedDeque(Deque<E> delegate, @NullableDecl Object mutex) {
+    SynchronizedDeque(Deque<E> delegate, @CheckForNull Object mutex) {
       super(delegate, mutex);
     }
 
@@ -1754,6 +1828,7 @@ public E removeLast() {
     }
 
     @Override
+    @CheckForNull
     public E pollFirst() {
       synchronized (mutex) {
         return delegate().pollFirst();
@@ -1761,6 +1836,7 @@ public E pollFirst() {
     }
 
     @Override
+    @CheckForNull
     public E pollLast() {
       synchronized (mutex) {
         return delegate().pollLast();
@@ -1782,6 +1858,7 @@ public E getLast() {
     }
 
     @Override
+    @CheckForNull
     public E peekFirst() {
       synchronized (mutex) {
         return delegate().peekFirst();
@@ -1789,6 +1866,7 @@ public E peekFirst() {
     }
 
     @Override
+    @CheckForNull
     public E peekLast() {
       synchronized (mutex) {
         return delegate().peekLast();
@@ -1796,14 +1874,14 @@ public E peekLast() {
     }
 
     @Override
-    public boolean removeFirstOccurrence(Object o) {
+    public boolean removeFirstOccurrence(@CheckForNull Object o) {
       synchronized (mutex) {
         return delegate().removeFirstOccurrence(o);
       }
     }
 
     @Override
-    public boolean removeLastOccurrence(Object o) {
+    public boolean removeLastOccurrence(@CheckForNull Object o) {
       synchronized (mutex) {
         return delegate().removeLastOccurrence(o);
       }
@@ -1833,14 +1911,16 @@ public Iterator<E> descendingIterator() {
     private static final long serialVersionUID = 0;
   }
 
-  static <R, C, V> Table<R, C, V> table(Table<R, C, V> table, Object mutex) {
+  static <R extends @Nullable Object, C extends @Nullable Object, V extends @Nullable Object>
+      Table<R, C, V> table(Table<R, C, V> table, @CheckForNull Object mutex) {
     return new SynchronizedTable<>(table, mutex);
   }
 
-  private static final class SynchronizedTable<R, C, V> extends SynchronizedObject
-      implements Table<R, C, V> {
+  private static final class SynchronizedTable<
+          R extends @Nullable Object, C extends @Nullable Object, V extends @Nullable Object>
+      extends SynchronizedObject implements Table<R, C, V> {
 
-    SynchronizedTable(Table<R, C, V> delegate, Object mutex) {
+    SynchronizedTable(Table<R, C, V> delegate, @CheckForNull Object mutex) {
       super(delegate, mutex);
     }
 
@@ -1851,35 +1931,36 @@ Table<R, C, V> delegate() {
     }
 
     @Override
-    public boolean contains(@NullableDecl Object rowKey, @NullableDecl Object columnKey) {
+    public boolean contains(@CheckForNull Object rowKey, @CheckForNull Object columnKey) {
       synchronized (mutex) {
         return delegate().contains(rowKey, columnKey);
       }
     }
 
     @Override
-    public boolean containsRow(@NullableDecl Object rowKey) {
+    public boolean containsRow(@CheckForNull Object rowKey) {
       synchronized (mutex) {
         return delegate().containsRow(rowKey);
       }
     }
 
     @Override
-    public boolean containsColumn(@NullableDecl Object columnKey) {
+    public boolean containsColumn(@CheckForNull Object columnKey) {
       synchronized (mutex) {
         return delegate().containsColumn(columnKey);
       }
     }
 
     @Override
-    public boolean containsValue(@NullableDecl Object value) {
+    public boolean containsValue(@CheckForNull Object value) {
       synchronized (mutex) {
         return delegate().containsValue(value);
       }
     }
 
     @Override
-    public V get(@NullableDecl Object rowKey, @NullableDecl Object columnKey) {
+    @CheckForNull
+    public V get(@CheckForNull Object rowKey, @CheckForNull Object columnKey) {
       synchronized (mutex) {
         return delegate().get(rowKey, columnKey);
       }
@@ -1907,7 +1988,8 @@ public void clear() {
     }
 
     @Override
-    public V put(@NullableDecl R rowKey, @NullableDecl C columnKey, @NullableDecl V value) {
+    @CheckForNull
+    public V put(R rowKey, C columnKey, V value) {
       synchronized (mutex) {
         return delegate().put(rowKey, columnKey, value);
       }
@@ -1921,21 +2003,22 @@ public void putAll(Table<? extends R, ? extends C, ? extends V> table) {
     }
 
     @Override
-    public V remove(@NullableDecl Object rowKey, @NullableDecl Object columnKey) {
+    @CheckForNull
+    public V remove(@CheckForNull Object rowKey, @CheckForNull Object columnKey) {
       synchronized (mutex) {
         return delegate().remove(rowKey, columnKey);
       }
     }
 
     @Override
-    public Map<C, V> row(@NullableDecl R rowKey) {
+    public Map<C, V> row(R rowKey) {
       synchronized (mutex) {
         return map(delegate().row(rowKey), mutex);
       }
     }
 
     @Override
-    public Map<R, V> column(@NullableDecl C columnKey) {
+    public Map<R, V> column(C columnKey) {
       synchronized (mutex) {
         return map(delegate().column(columnKey), mutex);
       }
@@ -2009,7 +2092,7 @@ public int hashCode() {
     }
 
     @Override
-    public boolean equals(@NullableDecl Object obj) {
+    public boolean equals(@CheckForNull Object obj) {
       if (this == obj) {
         return true;
       }
diff --git a/android/guava/src/com/google/common/collect/Table.java b/android/guava/src/com/google/common/collect/Table.java
index 13487941f47b..3c9e7ec7a471 100644
--- a/android/guava/src/com/google/common/collect/Table.java
+++ b/android/guava/src/com/google/common/collect/Table.java
@@ -24,7 +24,8 @@
 import java.util.Collection;
 import java.util.Map;
 import java.util.Set;
-import org.checkerframework.checker.nullness.compatqual.NullableDecl;
+import javax.annotation.CheckForNull;
+import org.checkerframework.checker.nullness.qual.Nullable;
 
 /**
  * A collection that associates an ordered pair of keys, called a row key and a column key, with a
@@ -45,7 +46,7 @@
  * UnsupportedOperationException}.
  *
  * <p>See the Guava User Guide article on <a href=
- * "https://github.com/google/guava/wiki/NewCollectionTypesExplained#table"> {@code Table}</a>.
+ * "https://github.com/google/guava/wiki/NewCollectionTypesExplained#table">{@code Table}</a>.
  *
  * @author Jared Levy
  * @param <R> the type of the table row keys
@@ -55,7 +56,9 @@
  */
 @DoNotMock("Use ImmutableTable, HashBasedTable, or another implementation")
 @GwtCompatible
-public interface Table<R, C, V> {
+@ElementTypesAreNonnullByDefault
+public interface Table<
+    R extends @Nullable Object, C extends @Nullable Object, V extends @Nullable Object> {
   // TODO(jlevy): Consider adding methods similar to ConcurrentMap methods.
 
   // Accessors
@@ -67,29 +70,29 @@ public interface Table<R, C, V> {
    * @param columnKey key of column to search for
    */
   boolean contains(
-      @NullableDecl @CompatibleWith("R") Object rowKey,
-      @NullableDecl @CompatibleWith("C") Object columnKey);
+      @CompatibleWith("R") @CheckForNull Object rowKey,
+      @CompatibleWith("C") @CheckForNull Object columnKey);
 
   /**
    * Returns {@code true} if the table contains a mapping with the specified row key.
    *
    * @param rowKey key of row to search for
    */
-  boolean containsRow(@NullableDecl @CompatibleWith("R") Object rowKey);
+  boolean containsRow(@CompatibleWith("R") @CheckForNull Object rowKey);
 
   /**
    * Returns {@code true} if the table contains a mapping with the specified column.
    *
    * @param columnKey key of column to search for
    */
-  boolean containsColumn(@NullableDecl @CompatibleWith("C") Object columnKey);
+  boolean containsColumn(@CompatibleWith("C") @CheckForNull Object columnKey);
 
   /**
    * Returns {@code true} if the table contains a mapping with the specified value.
    *
    * @param value value to search for
    */
-  boolean containsValue(@NullableDecl @CompatibleWith("V") Object value);
+  boolean containsValue(@CompatibleWith("V") @CheckForNull Object value);
 
   /**
    * Returns the value corresponding to the given row and column keys, or {@code null} if no such
@@ -98,10 +101,10 @@ boolean contains(
    * @param rowKey key of row to search for
    * @param columnKey key of column to search for
    */
-  @NullableDecl
+  @CheckForNull
   V get(
-      @NullableDecl @CompatibleWith("R") Object rowKey,
-      @NullableDecl @CompatibleWith("C") Object columnKey);
+      @CompatibleWith("R") @CheckForNull Object rowKey,
+      @CompatibleWith("C") @CheckForNull Object columnKey);
 
   /** Returns {@code true} if the table contains no mappings. */
   boolean isEmpty();
@@ -114,7 +117,7 @@ V get(
    * cell views, as returned by {@link #cellSet}, are equal.
    */
   @Override
-  boolean equals(@NullableDecl Object obj);
+  boolean equals(@CheckForNull Object obj);
 
   /**
    * Returns the hash code for this table. The hash code of a table is defined as the hash code of
@@ -139,8 +142,8 @@ V get(
    *     for the keys
    */
   @CanIgnoreReturnValue
-  @NullableDecl
-  V put(R rowKey, C columnKey, V value);
+  @CheckForNull
+  V put(@ParametricNullness R rowKey, @ParametricNullness C columnKey, @ParametricNullness V value);
 
   /**
    * Copies all mappings from the specified table to this table. The effect is equivalent to calling
@@ -158,10 +161,10 @@ V get(
    * @return the value previously associated with the keys, or {@code null} if no such value existed
    */
   @CanIgnoreReturnValue
-  @NullableDecl
+  @CheckForNull
   V remove(
-      @NullableDecl @CompatibleWith("R") Object rowKey,
-      @NullableDecl @CompatibleWith("C") Object columnKey);
+      @CompatibleWith("R") @CheckForNull Object rowKey,
+      @CompatibleWith("C") @CheckForNull Object columnKey);
 
   // Views
 
@@ -175,7 +178,7 @@ V remove(
    * @param rowKey key of row to search for in the table
    * @return the corresponding map from column keys to values
    */
-  Map<C, V> row(R rowKey);
+  Map<C, V> row(@ParametricNullness R rowKey);
 
   /**
    * Returns a view of all mappings that have the given column key. For each row key / column key /
@@ -187,7 +190,7 @@ V remove(
    * @param columnKey key of column to search for in the table
    * @return the corresponding map from row keys to values
    */
-  Map<R, V> column(C columnKey);
+  Map<R, V> column(@ParametricNullness C columnKey);
 
   /**
    * Returns a set of all row key / column key / value triplets. Changes to the returned set will
@@ -253,17 +256,18 @@ V remove(
    *
    * @since 7.0
    */
-  interface Cell<R, C, V> {
+  interface Cell<
+      R extends @Nullable Object, C extends @Nullable Object, V extends @Nullable Object> {
     /** Returns the row key of this cell. */
-    @NullableDecl
+    @ParametricNullness
     R getRowKey();
 
     /** Returns the column key of this cell. */
-    @NullableDecl
+    @ParametricNullness
     C getColumnKey();
 
     /** Returns the value of this cell. */
-    @NullableDecl
+    @ParametricNullness
     V getValue();
 
     /**
@@ -271,7 +275,7 @@ interface Cell<R, C, V> {
      * equal row keys, column keys, and values.
      */
     @Override
-    boolean equals(@NullableDecl Object obj);
+    boolean equals(@CheckForNull Object obj);
 
     /**
      * Returns the hash code of this cell.
diff --git a/android/guava/src/com/google/common/collect/Tables.java b/android/guava/src/com/google/common/collect/Tables.java
index 77c920cda220..ab67fae9fabd 100644
--- a/android/guava/src/com/google/common/collect/Tables.java
+++ b/android/guava/src/com/google/common/collect/Tables.java
@@ -18,6 +18,7 @@
 
 import static com.google.common.base.Preconditions.checkArgument;
 import static com.google.common.base.Preconditions.checkNotNull;
+import static com.google.common.collect.NullnessCasts.uncheckedCastNullableTToT;
 
 import com.google.common.annotations.Beta;
 import com.google.common.annotations.GwtCompatible;
@@ -33,19 +34,21 @@
 import java.util.Set;
 import java.util.SortedMap;
 import java.util.SortedSet;
-import org.checkerframework.checker.nullness.compatqual.NullableDecl;
+import javax.annotation.CheckForNull;
+import org.checkerframework.checker.nullness.qual.Nullable;
 
 /**
  * Provides static methods that involve a {@code Table}.
  *
  * <p>See the Guava User Guide article on <a href=
- * "https://github.com/google/guava/wiki/CollectionUtilitiesExplained#tables"> {@code Tables}</a>.
+ * "https://github.com/google/guava/wiki/CollectionUtilitiesExplained#tables">{@code Tables}</a>.
  *
  * @author Jared Levy
  * @author Louis Wasserman
  * @since 7.0
  */
 @GwtCompatible
+@ElementTypesAreNonnullByDefault
 public final class Tables {
   private Tables() {}
 
@@ -58,33 +61,44 @@ private Tables() {}
    * @param columnKey the column key to be associated with the returned cell
    * @param value the value to be associated with the returned cell
    */
-  public static <R, C, V> Cell<R, C, V> immutableCell(
-      @NullableDecl R rowKey, @NullableDecl C columnKey, @NullableDecl V value) {
+  public static <R extends @Nullable Object, C extends @Nullable Object, V extends @Nullable Object>
+      Cell<R, C, V> immutableCell(
+          @ParametricNullness R rowKey,
+          @ParametricNullness C columnKey,
+          @ParametricNullness V value) {
     return new ImmutableCell<>(rowKey, columnKey, value);
   }
 
-  static final class ImmutableCell<R, C, V> extends AbstractCell<R, C, V> implements Serializable {
-    @NullableDecl private final R rowKey;
-    @NullableDecl private final C columnKey;
-    @NullableDecl private final V value;
-
-    ImmutableCell(@NullableDecl R rowKey, @NullableDecl C columnKey, @NullableDecl V value) {
+  static final class ImmutableCell<
+          R extends @Nullable Object, C extends @Nullable Object, V extends @Nullable Object>
+      extends AbstractCell<R, C, V> implements Serializable {
+    @ParametricNullness private final R rowKey;
+    @ParametricNullness private final C columnKey;
+    @ParametricNullness private final V value;
+
+    ImmutableCell(
+        @ParametricNullness R rowKey,
+        @ParametricNullness C columnKey,
+        @ParametricNullness V value) {
       this.rowKey = rowKey;
       this.columnKey = columnKey;
       this.value = value;
     }
 
     @Override
+    @ParametricNullness
     public R getRowKey() {
       return rowKey;
     }
 
     @Override
+    @ParametricNullness
     public C getColumnKey() {
       return columnKey;
     }
 
     @Override
+    @ParametricNullness
     public V getValue() {
       return value;
     }
@@ -92,12 +106,14 @@ public V getValue() {
     private static final long serialVersionUID = 0;
   }
 
-  abstract static class AbstractCell<R, C, V> implements Cell<R, C, V> {
+  abstract static class AbstractCell<
+          R extends @Nullable Object, C extends @Nullable Object, V extends @Nullable Object>
+      implements Cell<R, C, V> {
     // needed for serialization
     AbstractCell() {}
 
     @Override
-    public boolean equals(Object obj) {
+    public boolean equals(@CheckForNull Object obj) {
       if (obj == this) {
         return true;
       }
@@ -133,13 +149,16 @@ public String toString() {
    * columnKeySet().iterator()} doesn't. With a transposed {@link HashBasedTable}, it's the other
    * way around.
    */
-  public static <R, C, V> Table<C, R, V> transpose(Table<R, C, V> table) {
+  public static <R extends @Nullable Object, C extends @Nullable Object, V extends @Nullable Object>
+      Table<C, R, V> transpose(Table<R, C, V> table) {
     return (table instanceof TransposeTable)
         ? ((TransposeTable<R, C, V>) table).original
         : new TransposeTable<C, R, V>(table);
   }
 
-  private static class TransposeTable<C, R, V> extends AbstractTable<C, R, V> {
+  private static class TransposeTable<
+          C extends @Nullable Object, R extends @Nullable Object, V extends @Nullable Object>
+      extends AbstractTable<C, R, V> {
     final Table<R, C, V> original;
 
     TransposeTable(Table<R, C, V> original) {
@@ -152,7 +171,7 @@ public void clear() {
     }
 
     @Override
-    public Map<C, V> column(R columnKey) {
+    public Map<C, V> column(@ParametricNullness R columnKey) {
       return original.row(columnKey);
     }
 
@@ -167,32 +186,37 @@ public Map<R, Map<C, V>> columnMap() {
     }
 
     @Override
-    public boolean contains(@NullableDecl Object rowKey, @NullableDecl Object columnKey) {
+    public boolean contains(@CheckForNull Object rowKey, @CheckForNull Object columnKey) {
       return original.contains(columnKey, rowKey);
     }
 
     @Override
-    public boolean containsColumn(@NullableDecl Object columnKey) {
+    public boolean containsColumn(@CheckForNull Object columnKey) {
       return original.containsRow(columnKey);
     }
 
     @Override
-    public boolean containsRow(@NullableDecl Object rowKey) {
+    public boolean containsRow(@CheckForNull Object rowKey) {
       return original.containsColumn(rowKey);
     }
 
     @Override
-    public boolean containsValue(@NullableDecl Object value) {
+    public boolean containsValue(@CheckForNull Object value) {
       return original.containsValue(value);
     }
 
     @Override
-    public V get(@NullableDecl Object rowKey, @NullableDecl Object columnKey) {
+    @CheckForNull
+    public V get(@CheckForNull Object rowKey, @CheckForNull Object columnKey) {
       return original.get(columnKey, rowKey);
     }
 
     @Override
-    public V put(C rowKey, R columnKey, V value) {
+    @CheckForNull
+    public V put(
+        @ParametricNullness C rowKey,
+        @ParametricNullness R columnKey,
+        @ParametricNullness V value) {
       return original.put(columnKey, rowKey, value);
     }
 
@@ -202,12 +226,13 @@ public void putAll(Table<? extends C, ? extends R, ? extends V> table) {
     }
 
     @Override
-    public V remove(@NullableDecl Object rowKey, @NullableDecl Object columnKey) {
+    @CheckForNull
+    public V remove(@CheckForNull Object rowKey, @CheckForNull Object columnKey) {
       return original.remove(columnKey, rowKey);
     }
 
     @Override
-    public Map<R, V> row(C rowKey) {
+    public Map<R, V> row(@ParametricNullness C rowKey) {
       return original.column(rowKey);
     }
 
@@ -316,12 +341,22 @@ public static <R, C, V> Table<R, C, V> newCustomTable(
    * @since 10.0
    */
   @Beta
-  public static <R, C, V1, V2> Table<R, C, V2> transformValues(
-      Table<R, C, V1> fromTable, Function<? super V1, V2> function) {
+  public static <
+          R extends @Nullable Object,
+          C extends @Nullable Object,
+          V1 extends @Nullable Object,
+          V2 extends @Nullable Object>
+      Table<R, C, V2> transformValues(
+          Table<R, C, V1> fromTable, Function<? super V1, V2> function) {
     return new TransformedTable<>(fromTable, function);
   }
 
-  private static class TransformedTable<R, C, V1, V2> extends AbstractTable<R, C, V2> {
+  private static class TransformedTable<
+          R extends @Nullable Object,
+          C extends @Nullable Object,
+          V1 extends @Nullable Object,
+          V2 extends @Nullable Object>
+      extends AbstractTable<R, C, V2> {
     final Table<R, C, V1> fromTable;
     final Function<? super V1, V2> function;
 
@@ -331,15 +366,19 @@ private static class TransformedTable<R, C, V1, V2> extends AbstractTable<R, C,
     }
 
     @Override
-    public boolean contains(Object rowKey, Object columnKey) {
+    public boolean contains(@CheckForNull Object rowKey, @CheckForNull Object columnKey) {
       return fromTable.contains(rowKey, columnKey);
     }
 
     @Override
-    public V2 get(Object rowKey, Object columnKey) {
+    @CheckForNull
+    public V2 get(@CheckForNull Object rowKey, @CheckForNull Object columnKey) {
       // The function is passed a null input only when the table contains a null
       // value.
-      return contains(rowKey, columnKey) ? function.apply(fromTable.get(rowKey, columnKey)) : null;
+      // The cast is safe because of the contains() check.
+      return contains(rowKey, columnKey)
+          ? function.apply(uncheckedCastNullableTToT(fromTable.get(rowKey, columnKey)))
+          : null;
     }
 
     @Override
@@ -353,7 +392,11 @@ public void clear() {
     }
 
     @Override
-    public V2 put(R rowKey, C columnKey, V2 value) {
+    @CheckForNull
+    public V2 put(
+        @ParametricNullness R rowKey,
+        @ParametricNullness C columnKey,
+        @ParametricNullness V2 value) {
       throw new UnsupportedOperationException();
     }
 
@@ -363,19 +406,21 @@ public void putAll(Table<? extends R, ? extends C, ? extends V2> table) {
     }
 
     @Override
-    public V2 remove(Object rowKey, Object columnKey) {
+    @CheckForNull
+    public V2 remove(@CheckForNull Object rowKey, @CheckForNull Object columnKey) {
       return contains(rowKey, columnKey)
-          ? function.apply(fromTable.remove(rowKey, columnKey))
+          // The cast is safe because of the contains() check.
+          ? function.apply(uncheckedCastNullableTToT(fromTable.remove(rowKey, columnKey)))
           : null;
     }
 
     @Override
-    public Map<C, V2> row(R rowKey) {
+    public Map<C, V2> row(@ParametricNullness R rowKey) {
       return Maps.transformValues(fromTable.row(rowKey), function);
     }
 
     @Override
-    public Map<R, V2> column(C columnKey) {
+    public Map<R, V2> column(@ParametricNullness C columnKey) {
       return Maps.transformValues(fromTable.column(columnKey), function);
     }
 
@@ -446,13 +491,14 @@ public Map<R, V2> apply(Map<R, V1> column) {
    *
    * @since 11.0
    */
-  public static <R, C, V> Table<R, C, V> unmodifiableTable(
-      Table<? extends R, ? extends C, ? extends V> table) {
+  public static <R extends @Nullable Object, C extends @Nullable Object, V extends @Nullable Object>
+      Table<R, C, V> unmodifiableTable(Table<? extends R, ? extends C, ? extends V> table) {
     return new UnmodifiableTable<>(table);
   }
 
-  private static class UnmodifiableTable<R, C, V> extends ForwardingTable<R, C, V>
-      implements Serializable {
+  private static class UnmodifiableTable<
+          R extends @Nullable Object, C extends @Nullable Object, V extends @Nullable Object>
+      extends ForwardingTable<R, C, V> implements Serializable {
     final Table<? extends R, ? extends C, ? extends V> delegate;
 
     UnmodifiableTable(Table<? extends R, ? extends C, ? extends V> delegate) {
@@ -476,7 +522,7 @@ public void clear() {
     }
 
     @Override
-    public Map<R, V> column(@NullableDecl C columnKey) {
+    public Map<R, V> column(@ParametricNullness C columnKey) {
       return Collections.unmodifiableMap(super.column(columnKey));
     }
 
@@ -492,7 +538,11 @@ public Map<C, Map<R, V>> columnMap() {
     }
 
     @Override
-    public V put(@NullableDecl R rowKey, @NullableDecl C columnKey, @NullableDecl V value) {
+    @CheckForNull
+    public V put(
+        @ParametricNullness R rowKey,
+        @ParametricNullness C columnKey,
+        @ParametricNullness V value) {
       throw new UnsupportedOperationException();
     }
 
@@ -502,12 +552,13 @@ public void putAll(Table<? extends R, ? extends C, ? extends V> table) {
     }
 
     @Override
-    public V remove(@NullableDecl Object rowKey, @NullableDecl Object columnKey) {
+    @CheckForNull
+    public V remove(@CheckForNull Object rowKey, @CheckForNull Object columnKey) {
       throw new UnsupportedOperationException();
     }
 
     @Override
-    public Map<C, V> row(@NullableDecl R rowKey) {
+    public Map<C, V> row(@ParametricNullness R rowKey) {
       return Collections.unmodifiableMap(super.row(rowKey));
     }
 
@@ -543,8 +594,9 @@ public Collection<V> values() {
    * @since 11.0
    */
   @Beta
-  public static <R, C, V> RowSortedTable<R, C, V> unmodifiableRowSortedTable(
-      RowSortedTable<R, ? extends C, ? extends V> table) {
+  public static <R extends @Nullable Object, C extends @Nullable Object, V extends @Nullable Object>
+      RowSortedTable<R, C, V> unmodifiableRowSortedTable(
+          RowSortedTable<R, ? extends C, ? extends V> table) {
     /*
      * It's not ? extends R, because it's technically not covariant in R. Specifically,
      * table.rowMap().comparator() could return a comparator that only works for the ? extends R.
@@ -553,8 +605,9 @@ public static <R, C, V> RowSortedTable<R, C, V> unmodifiableRowSortedTable(
     return new UnmodifiableRowSortedMap<>(table);
   }
 
-  static final class UnmodifiableRowSortedMap<R, C, V> extends UnmodifiableTable<R, C, V>
-      implements RowSortedTable<R, C, V> {
+  static final class UnmodifiableRowSortedMap<
+          R extends @Nullable Object, C extends @Nullable Object, V extends @Nullable Object>
+      extends UnmodifiableTable<R, C, V> implements RowSortedTable<R, C, V> {
 
     public UnmodifiableRowSortedMap(RowSortedTable<R, ? extends C, ? extends V> delegate) {
       super(delegate);
@@ -580,7 +633,8 @@ public SortedSet<R> rowKeySet() {
   }
 
   @SuppressWarnings("unchecked")
-  private static <K, V> Function<Map<K, V>, Map<K, V>> unmodifiableWrapper() {
+  private static <K extends @Nullable Object, V extends @Nullable Object>
+      Function<Map<K, V>, Map<K, V>> unmodifiableWrapper() {
     return (Function) UNMODIFIABLE_WRAPPER;
   }
 
@@ -621,11 +675,12 @@ public Map<Object, Object> apply(Map<Object, Object> input) {
    * @return a synchronized view of the specified table
    * @since 22.0
    */
-  public static <R, C, V> Table<R, C, V> synchronizedTable(Table<R, C, V> table) {
+  public static <R extends @Nullable Object, C extends @Nullable Object, V extends @Nullable Object>
+      Table<R, C, V> synchronizedTable(Table<R, C, V> table) {
     return Synchronized.table(table, null);
   }
 
-  static boolean equalsImpl(Table<?, ?, ?> table, @NullableDecl Object obj) {
+  static boolean equalsImpl(Table<?, ?, ?> table, @CheckForNull Object obj) {
     if (obj == table) {
       return true;
     } else if (obj instanceof Table) {
diff --git a/android/guava/src/com/google/common/collect/TopKSelector.java b/android/guava/src/com/google/common/collect/TopKSelector.java
index 10b31bdfbb4b..32959630bdda 100644
--- a/android/guava/src/com/google/common/collect/TopKSelector.java
+++ b/android/guava/src/com/google/common/collect/TopKSelector.java
@@ -18,6 +18,7 @@
 
 import static com.google.common.base.Preconditions.checkArgument;
 import static com.google.common.base.Preconditions.checkNotNull;
+import static com.google.common.collect.NullnessCasts.uncheckedCastNullableTToT;
 
 import com.google.common.annotations.GwtCompatible;
 import com.google.common.math.IntMath;
@@ -27,7 +28,8 @@
 import java.util.Comparator;
 import java.util.Iterator;
 import java.util.List;
-import org.checkerframework.checker.nullness.compatqual.NullableDecl;
+import javax.annotation.CheckForNull;
+import org.checkerframework.checker.nullness.qual.Nullable;
 
 /**
  * An accumulator that selects the "top" {@code k} elements added to it, relative to a provided
@@ -51,7 +53,9 @@
  * @author Louis Wasserman
  */
 @GwtCompatible
-final class TopKSelector<T> {
+@ElementTypesAreNonnullByDefault
+final class TopKSelector<
+    T extends @Nullable Object> {
 
   /**
    * Returns a {@code TopKSelector} that collects the lowest {@code k} elements added to it,
@@ -70,7 +74,8 @@ public static <T extends Comparable<? super T>> TopKSelector<T> least(int k) {
    *
    * @throws IllegalArgumentException if {@code k < 0} or {@code k > Integer.MAX_VALUE / 2}
    */
-  public static <T> TopKSelector<T> least(int k, Comparator<? super T> comparator) {
+  public static <T extends @Nullable Object> TopKSelector<T> least(
+      int k, Comparator<? super T> comparator) {
     return new TopKSelector<T>(comparator, k);
   }
 
@@ -91,7 +96,8 @@ public static <T extends Comparable<? super T>> TopKSelector<T> greatest(int k)
    *
    * @throws IllegalArgumentException if {@code k < 0} or {@code k > Integer.MAX_VALUE / 2}
    */
-  public static <T> TopKSelector<T> greatest(int k, Comparator<? super T> comparator) {
+  public static <T extends @Nullable Object> TopKSelector<T> greatest(
+      int k, Comparator<? super T> comparator) {
     return new TopKSelector<T>(Ordering.from(comparator).reverse(), k);
   }
 
@@ -103,14 +109,14 @@ public static <T> TopKSelector<T> greatest(int k, Comparator<? super T> comparat
    * for the top k elements. Whenever the buffer is filled, we quickselect the top k elements to the
    * range [0, k) and ignore the remaining elements.
    */
-  private final T[] buffer;
+  private final @Nullable T[] buffer;
   private int bufferSize;
 
   /**
    * The largest of the lowest k elements we've seen so far relative to this comparator. If
    * bufferSize ≥ k, then we can ignore any elements greater than this value.
    */
-  @NullableDecl private T threshold;
+  @CheckForNull private T threshold;
 
   private TopKSelector(Comparator<? super T> comparator, int k) {
     this.comparator = checkNotNull(comparator, "comparator");
@@ -126,7 +132,7 @@ private TopKSelector(Comparator<? super T> comparator, int k) {
    * Adds {@code elem} as a candidate for the top {@code k} elements. This operation takes amortized
    * O(1) time.
    */
-  public void offer(@NullableDecl T elem) {
+  public void offer(@ParametricNullness T elem) {
     if (k == 0) {
       return;
     } else if (bufferSize == 0) {
@@ -135,10 +141,12 @@ public void offer(@NullableDecl T elem) {
       bufferSize = 1;
     } else if (bufferSize < k) {
       buffer[bufferSize++] = elem;
-      if (comparator.compare(elem, threshold) > 0) {
+      // uncheckedCastNullableTToT is safe because bufferSize > 0.
+      if (comparator.compare(elem, uncheckedCastNullableTToT(threshold)) > 0) {
         threshold = elem;
       }
-    } else if (comparator.compare(elem, threshold) < 0) {
+      // uncheckedCastNullableTToT is safe because bufferSize > 0.
+    } else if (comparator.compare(elem, uncheckedCastNullableTToT(threshold)) < 0) {
       // Otherwise, we can ignore elem; we've seen k better elements.
       buffer[bufferSize++] = elem;
       if (bufferSize == 2 * k) {
@@ -176,16 +184,20 @@ private void trim() {
       }
       iterations++;
       if (iterations >= maxIterations) {
+        @SuppressWarnings("nullness") // safe because we pass sort() a range that contains real Ts
+        T[] castBuffer = (T[]) buffer;
         // We've already taken O(k log k), let's make sure we don't take longer than O(k log k).
-        Arrays.sort(buffer, left, right, comparator);
+        Arrays.sort(castBuffer, left, right + 1, comparator);
         break;
       }
     }
     bufferSize = k;
 
-    threshold = buffer[minThresholdPosition];
+    threshold = uncheckedCastNullableTToT(buffer[minThresholdPosition]);
     for (int i = minThresholdPosition + 1; i < k; i++) {
-      if (comparator.compare(buffer[i], threshold) > 0) {
+      if (comparator.compare(
+              uncheckedCastNullableTToT(buffer[i]), uncheckedCastNullableTToT(threshold))
+          > 0) {
         threshold = buffer[i];
       }
     }
@@ -198,12 +210,12 @@ private void trim() {
    * (pivotNewIndex, right] is greater than pivotValue.
    */
   private int partition(int left, int right, int pivotIndex) {
-    T pivotValue = buffer[pivotIndex];
+    T pivotValue = uncheckedCastNullableTToT(buffer[pivotIndex]);
     buffer[pivotIndex] = buffer[right];
 
     int pivotNewIndex = left;
     for (int i = left; i < right; i++) {
-      if (comparator.compare(buffer[i], pivotValue) < 0) {
+      if (comparator.compare(uncheckedCastNullableTToT(buffer[i]), pivotValue) < 0) {
         swap(pivotNewIndex, i);
         pivotNewIndex++;
       }
@@ -253,7 +265,9 @@ public void offerAll(Iterator<? extends T> elements) {
    * this {@code TopKSelector}. This method returns in O(k log k) time.
    */
   public List<T> topK() {
-    Arrays.sort(buffer, 0, bufferSize, comparator);
+    @SuppressWarnings("nullness") // safe because we pass sort() a range that contains real Ts
+    T[] castBuffer = (T[]) buffer;
+    Arrays.sort(castBuffer, 0, bufferSize, comparator);
     if (bufferSize > k) {
       Arrays.fill(buffer, k, buffer.length, null);
       bufferSize = k;
diff --git a/android/guava/src/com/google/common/collect/TransformedIterator.java b/android/guava/src/com/google/common/collect/TransformedIterator.java
index b7214b8abd75..2456cecde991 100644
--- a/android/guava/src/com/google/common/collect/TransformedIterator.java
+++ b/android/guava/src/com/google/common/collect/TransformedIterator.java
@@ -20,6 +20,7 @@
 
 import com.google.common.annotations.GwtCompatible;
 import java.util.Iterator;
+import org.checkerframework.checker.nullness.qual.Nullable;
 
 /**
  * An iterator that transforms a backing iterator; for internal use. This avoids the object overhead
@@ -28,14 +29,17 @@
  * @author Louis Wasserman
  */
 @GwtCompatible
-abstract class TransformedIterator<F, T> implements Iterator<T> {
+@ElementTypesAreNonnullByDefault
+abstract class TransformedIterator<F extends @Nullable Object, T extends @Nullable Object>
+    implements Iterator<T> {
   final Iterator<? extends F> backingIterator;
 
   TransformedIterator(Iterator<? extends F> backingIterator) {
     this.backingIterator = checkNotNull(backingIterator);
   }
 
-  abstract T transform(F from);
+  @ParametricNullness
+  abstract T transform(@ParametricNullness F from);
 
   @Override
   public final boolean hasNext() {
@@ -43,6 +47,7 @@ public final boolean hasNext() {
   }
 
   @Override
+  @ParametricNullness
   public final T next() {
     return transform(backingIterator.next());
   }
diff --git a/android/guava/src/com/google/common/collect/TransformedListIterator.java b/android/guava/src/com/google/common/collect/TransformedListIterator.java
index ac2eea1e1516..66b42e4c6048 100644
--- a/android/guava/src/com/google/common/collect/TransformedListIterator.java
+++ b/android/guava/src/com/google/common/collect/TransformedListIterator.java
@@ -19,6 +19,7 @@
 import com.google.common.annotations.GwtCompatible;
 import com.google.common.base.Function;
 import java.util.ListIterator;
+import org.checkerframework.checker.nullness.qual.Nullable;
 
 /**
  * An iterator that transforms a backing list iterator; for internal use. This avoids the object
@@ -27,8 +28,9 @@
  * @author Louis Wasserman
  */
 @GwtCompatible
-abstract class TransformedListIterator<F, T> extends TransformedIterator<F, T>
-    implements ListIterator<T> {
+@ElementTypesAreNonnullByDefault
+abstract class TransformedListIterator<F extends @Nullable Object, T extends @Nullable Object>
+    extends TransformedIterator<F, T> implements ListIterator<T> {
   TransformedListIterator(ListIterator<? extends F> backingIterator) {
     super(backingIterator);
   }
@@ -43,6 +45,7 @@ public final boolean hasPrevious() {
   }
 
   @Override
+  @ParametricNullness
   public final T previous() {
     return transform(backingIterator().previous());
   }
@@ -58,12 +61,12 @@ public final int previousIndex() {
   }
 
   @Override
-  public void set(T element) {
+  public void set(@ParametricNullness T element) {
     throw new UnsupportedOperationException();
   }
 
   @Override
-  public void add(T element) {
+  public void add(@ParametricNullness T element) {
     throw new UnsupportedOperationException();
   }
 }
diff --git a/android/guava/src/com/google/common/collect/TreeBasedTable.java b/android/guava/src/com/google/common/collect/TreeBasedTable.java
index dc665eb24e9c..9ef210a54a62 100644
--- a/android/guava/src/com/google/common/collect/TreeBasedTable.java
+++ b/android/guava/src/com/google/common/collect/TreeBasedTable.java
@@ -18,9 +18,9 @@
 
 import static com.google.common.base.Preconditions.checkArgument;
 import static com.google.common.base.Preconditions.checkNotNull;
+import static java.util.Objects.requireNonNull;
 
 import com.google.common.annotations.GwtCompatible;
-import com.google.common.base.Function;
 import com.google.common.base.Supplier;
 import java.io.Serializable;
 import java.util.Comparator;
@@ -31,7 +31,7 @@
 import java.util.SortedMap;
 import java.util.SortedSet;
 import java.util.TreeMap;
-import org.checkerframework.checker.nullness.compatqual.NullableDecl;
+import javax.annotation.CheckForNull;
 
 /**
  * Implementation of {@code Table} whose row keys and column keys are ordered by their natural
@@ -59,13 +59,14 @@
  * concurrently and one of the threads modifies the table, it must be synchronized externally.
  *
  * <p>See the Guava User Guide article on <a href=
- * "https://github.com/google/guava/wiki/NewCollectionTypesExplained#table"> {@code Table}</a>.
+ * "https://github.com/google/guava/wiki/NewCollectionTypesExplained#table">{@code Table}</a>.
  *
  * @author Jared Levy
  * @author Louis Wasserman
  * @since 7.0
  */
 @GwtCompatible(serializable = true)
+@ElementTypesAreNonnullByDefault
 public class TreeBasedTable<R, C, V> extends StandardRowSortedTable<R, C, V> {
   private final Comparator<? super C> columnComparator;
 
@@ -135,7 +136,11 @@ public static <R, C, V> TreeBasedTable<R, C, V> create(TreeBasedTable<R, C, ? ex
    */
   @Deprecated
   public Comparator<? super R> rowComparator() {
-    return rowKeySet().comparator();
+    /*
+     * requireNonNull is safe because the factories require non-null Comparators, which they pass on
+     * to the backing collections.
+     */
+    return requireNonNull(rowKeySet().comparator());
   }
 
   /**
@@ -169,14 +174,14 @@ public SortedMap<C, V> row(R rowKey) {
   }
 
   private class TreeRow extends Row implements SortedMap<C, V> {
-    @NullableDecl final C lowerBound;
-    @NullableDecl final C upperBound;
+    @CheckForNull final C lowerBound;
+    @CheckForNull final C upperBound;
 
     TreeRow(R rowKey) {
       this(rowKey, null, null);
     }
 
-    TreeRow(R rowKey, @NullableDecl C lowerBound, @NullableDecl C upperBound) {
+    TreeRow(R rowKey, @CheckForNull C lowerBound, @CheckForNull C upperBound) {
       super(rowKey);
       this.lowerBound = lowerBound;
       this.upperBound = upperBound;
@@ -201,7 +206,7 @@ int compare(Object a, Object b) {
       return cmp.compare(a, b);
     }
 
-    boolean rangeContains(@NullableDecl Object o) {
+    boolean rangeContains(@CheckForNull Object o) {
       return o != null
           && (lowerBound == null || compare(lowerBound, o) <= 0)
           && (upperBound == null || compare(upperBound, o) > 0);
@@ -227,43 +232,36 @@ public SortedMap<C, V> tailMap(C fromKey) {
 
     @Override
     public C firstKey() {
-      SortedMap<C, V> backing = backingRowMap();
-      if (backing == null) {
+      updateBackingRowMapField();
+      if (backingRowMap == null) {
         throw new NoSuchElementException();
       }
-      return backingRowMap().firstKey();
+      return ((SortedMap<C, V>) backingRowMap).firstKey();
     }
 
     @Override
     public C lastKey() {
-      SortedMap<C, V> backing = backingRowMap();
-      if (backing == null) {
+      updateBackingRowMapField();
+      if (backingRowMap == null) {
         throw new NoSuchElementException();
       }
-      return backingRowMap().lastKey();
+      return ((SortedMap<C, V>) backingRowMap).lastKey();
     }
 
-    @NullableDecl transient SortedMap<C, V> wholeRow;
+    @CheckForNull transient SortedMap<C, V> wholeRow;
 
-    /*
-     * If the row was previously empty, we check if there's a new row here every
-     * time we're queried.
-     */
-    SortedMap<C, V> wholeRow() {
+    // If the row was previously empty, we check if there's a new row here every time we're queried.
+    void updateWholeRowField() {
       if (wholeRow == null || (wholeRow.isEmpty() && backingMap.containsKey(rowKey))) {
         wholeRow = (SortedMap<C, V>) backingMap.get(rowKey);
       }
-      return wholeRow;
-    }
-
-    @Override
-    SortedMap<C, V> backingRowMap() {
-      return (SortedMap<C, V>) super.backingRowMap();
     }
 
     @Override
+    @CheckForNull
     SortedMap<C, V> computeBackingRowMap() {
-      SortedMap<C, V> map = wholeRow();
+      updateWholeRowField();
+      SortedMap<C, V> map = wholeRow;
       if (map != null) {
         if (lowerBound != null) {
           map = map.tailMap(lowerBound);
@@ -278,7 +276,8 @@ SortedMap<C, V> computeBackingRowMap() {
 
     @Override
     void maintainEmptyInvariant() {
-      if (wholeRow() != null && wholeRow.isEmpty()) {
+      updateWholeRowField();
+      if (wholeRow != null && wholeRow.isEmpty()) {
         backingMap.remove(rowKey);
         wholeRow = null;
         backingRowMap = null;
@@ -286,11 +285,12 @@ void maintainEmptyInvariant() {
     }
 
     @Override
-    public boolean containsKey(Object key) {
+    public boolean containsKey(@CheckForNull Object key) {
       return rangeContains(key) && super.containsKey(key);
     }
 
     @Override
+    @CheckForNull
     public V put(C key, V value) {
       checkArgument(rangeContains(checkNotNull(key)));
       return super.put(key, value);
@@ -312,24 +312,19 @@ public SortedMap<R, Map<C, V>> rowMap() {
   /** Overridden column iterator to return columns values in globally sorted order. */
   @Override
   Iterator<C> createColumnKeyIterator() {
-    final Comparator<? super C> comparator = columnComparator();
+    Comparator<? super C> comparator = columnComparator();
 
-    final Iterator<C> merged =
+    Iterator<C> merged =
         Iterators.mergeSorted(
             Iterables.transform(
-                backingMap.values(),
-                new Function<Map<C, V>, Iterator<C>>() {
-                  @Override
-                  public Iterator<C> apply(Map<C, V> input) {
-                    return input.keySet().iterator();
-                  }
-                }),
+                backingMap.values(), (Map<C, V> input) -> input.keySet().iterator()),
             comparator);
 
     return new AbstractIterator<C>() {
-      @NullableDecl C lastValue;
+      @CheckForNull C lastValue;
 
       @Override
+      @CheckForNull
       protected C computeNext() {
         while (merged.hasNext()) {
           C next = merged.next();
diff --git a/android/guava/src/com/google/common/collect/TreeMultimap.java b/android/guava/src/com/google/common/collect/TreeMultimap.java
index 85531e3e3b33..dd0c2f833c43 100644
--- a/android/guava/src/com/google/common/collect/TreeMultimap.java
+++ b/android/guava/src/com/google/common/collect/TreeMultimap.java
@@ -31,7 +31,7 @@
 import java.util.SortedSet;
 import java.util.TreeMap;
 import java.util.TreeSet;
-import org.checkerframework.checker.nullness.compatqual.NullableDecl;
+import org.checkerframework.checker.nullness.qual.Nullable;
 
 /**
  * Implementation of {@code Multimap} whose keys and values are ordered by their natural ordering or
@@ -64,15 +64,16 @@
  * with a call to {@link Multimaps#synchronizedSortedSetMultimap}.
  *
  * <p>See the Guava User Guide article on <a href=
- * "https://github.com/google/guava/wiki/NewCollectionTypesExplained#multimap"> {@code
- * Multimap}</a>.
+ * "https://github.com/google/guava/wiki/NewCollectionTypesExplained#multimap">{@code Multimap}</a>.
  *
  * @author Jared Levy
  * @author Louis Wasserman
  * @since 2.0
  */
 @GwtCompatible(serializable = true, emulated = true)
-public class TreeMultimap<K, V> extends AbstractSortedKeySortedSetMultimap<K, V> {
+@ElementTypesAreNonnullByDefault
+public class TreeMultimap<K extends @Nullable Object, V extends @Nullable Object>
+    extends AbstractSortedKeySortedSetMultimap<K, V> {
   private transient Comparator<? super K> keyComparator;
   private transient Comparator<? super V> valueComparator;
 
@@ -90,7 +91,7 @@ public static <K extends Comparable, V extends Comparable> TreeMultimap<K, V> cr
    * @param keyComparator the comparator that determines the key ordering
    * @param valueComparator the comparator that determines the value ordering
    */
-  public static <K, V> TreeMultimap<K, V> create(
+  public static <K extends @Nullable Object, V extends @Nullable Object> TreeMultimap<K, V> create(
       Comparator<? super K> keyComparator, Comparator<? super V> valueComparator) {
     return new TreeMultimap<>(checkNotNull(keyComparator), checkNotNull(valueComparator));
   }
@@ -134,11 +135,11 @@ Map<K, Collection<V>> createAsMap() {
    */
   @Override
   SortedSet<V> createCollection() {
-    return new TreeSet<V>(valueComparator);
+    return new TreeSet<>(valueComparator);
   }
 
   @Override
-  Collection<V> createCollection(@NullableDecl K key) {
+  Collection<V> createCollection(@ParametricNullness K key) {
     if (key == null) {
       keyComparator().compare(key, key);
     }
@@ -163,7 +164,7 @@ public Comparator<? super V> valueComparator() {
   /** @since 14.0 (present with return type {@code SortedSet} since 2.0) */
   @Override
   @GwtIncompatible // NavigableSet
-  public NavigableSet<V> get(@NullableDecl K key) {
+  public NavigableSet<V> get(@ParametricNullness K key) {
     return (NavigableSet<V>) super.get(key);
   }
 
diff --git a/android/guava/src/com/google/common/collect/TreeMultiset.java b/android/guava/src/com/google/common/collect/TreeMultiset.java
index dac0eab8869a..bcaa10881145 100644
--- a/android/guava/src/com/google/common/collect/TreeMultiset.java
+++ b/android/guava/src/com/google/common/collect/TreeMultiset.java
@@ -19,7 +19,8 @@
 import static com.google.common.base.Preconditions.checkArgument;
 import static com.google.common.base.Preconditions.checkState;
 import static com.google.common.collect.CollectPreconditions.checkNonnegative;
-import static com.google.common.collect.CollectPreconditions.checkRemove;
+import static com.google.common.collect.NullnessCasts.uncheckedCastNullableTToT;
+import static java.util.Objects.requireNonNull;
 
 import com.google.common.annotations.GwtCompatible;
 import com.google.common.annotations.GwtIncompatible;
@@ -34,7 +35,8 @@
 import java.util.ConcurrentModificationException;
 import java.util.Iterator;
 import java.util.NoSuchElementException;
-import org.checkerframework.checker.nullness.compatqual.NullableDecl;
+import javax.annotation.CheckForNull;
+import org.checkerframework.checker.nullness.qual.Nullable;
 
 /**
  * A multiset which maintains the ordering of its elements, according to either their natural order
@@ -47,15 +49,16 @@
  * java.util.Collection} contract, which is specified in terms of {@link Object#equals}.
  *
  * <p>See the Guava User Guide article on <a href=
- * "https://github.com/google/guava/wiki/NewCollectionTypesExplained#multiset"> {@code
- * Multiset}</a>.
+ * "https://github.com/google/guava/wiki/NewCollectionTypesExplained#multiset">{@code Multiset}</a>.
  *
  * @author Louis Wasserman
  * @author Jared Levy
  * @since 2.0
  */
 @GwtCompatible(emulated = true)
-public final class TreeMultiset<E> extends AbstractSortedMultiset<E> implements Serializable {
+@ElementTypesAreNonnullByDefault
+public final class TreeMultiset<E extends @Nullable Object> extends AbstractSortedMultiset<E>
+    implements Serializable {
 
   /**
    * Creates a new, empty multiset, sorted according to the elements' natural order. All elements
@@ -85,7 +88,8 @@ public static <E extends Comparable> TreeMultiset<E> create() {
    *     indicates that the elements' <i>natural ordering</i> should be used.
    */
   @SuppressWarnings("unchecked")
-  public static <E> TreeMultiset<E> create(@NullableDecl Comparator<? super E> comparator) {
+  public static <E extends @Nullable Object> TreeMultiset<E> create(
+      @CheckForNull Comparator<? super E> comparator) {
     return (comparator == null)
         ? new TreeMultiset<E>((Comparator) Ordering.natural())
         : new TreeMultiset<E>(comparator);
@@ -120,7 +124,7 @@ public static <E extends Comparable> TreeMultiset<E> create(Iterable<? extends E
   TreeMultiset(Comparator<? super E> comparator) {
     super(comparator);
     this.range = GeneralRange.all(comparator);
-    this.header = new AvlNode<E>(null, 1);
+    this.header = new AvlNode<>();
     successor(header, header);
     this.rootReference = new Reference<>();
   }
@@ -134,7 +138,7 @@ int nodeAggregate(AvlNode<?> node) {
       }
 
       @Override
-      long treeAggregate(@NullableDecl AvlNode<?> root) {
+      long treeAggregate(@CheckForNull AvlNode<?> root) {
         return (root == null) ? 0 : root.totalCount;
       }
     },
@@ -145,14 +149,14 @@ int nodeAggregate(AvlNode<?> node) {
       }
 
       @Override
-      long treeAggregate(@NullableDecl AvlNode<?> root) {
+      long treeAggregate(@CheckForNull AvlNode<?> root) {
         return (root == null) ? 0 : root.distinctElements;
       }
     };
 
     abstract int nodeAggregate(AvlNode<?> node);
 
-    abstract long treeAggregate(@NullableDecl AvlNode<?> root);
+    abstract long treeAggregate(@CheckForNull AvlNode<?> root);
   }
 
   private long aggregateForEntries(Aggregate aggr) {
@@ -167,11 +171,14 @@ private long aggregateForEntries(Aggregate aggr) {
     return total;
   }
 
-  private long aggregateBelowRange(Aggregate aggr, @NullableDecl AvlNode<E> node) {
+  private long aggregateBelowRange(Aggregate aggr, @CheckForNull AvlNode<E> node) {
     if (node == null) {
       return 0;
     }
-    int cmp = comparator().compare(range.getLowerEndpoint(), node.elem);
+    // The cast is safe because we call this method only if hasLowerBound().
+    int cmp =
+        comparator()
+            .compare(uncheckedCastNullableTToT(range.getLowerEndpoint()), node.getElement());
     if (cmp < 0) {
       return aggregateBelowRange(aggr, node.left);
     } else if (cmp == 0) {
@@ -190,11 +197,14 @@ private long aggregateBelowRange(Aggregate aggr, @NullableDecl AvlNode<E> node)
     }
   }
 
-  private long aggregateAboveRange(Aggregate aggr, @NullableDecl AvlNode<E> node) {
+  private long aggregateAboveRange(Aggregate aggr, @CheckForNull AvlNode<E> node) {
     if (node == null) {
       return 0;
     }
-    int cmp = comparator().compare(range.getUpperEndpoint(), node.elem);
+    // The cast is safe because we call this method only if hasUpperBound().
+    int cmp =
+        comparator()
+            .compare(uncheckedCastNullableTToT(range.getUpperEndpoint()), node.getElement());
     if (cmp > 0) {
       return aggregateAboveRange(aggr, node.right);
     } else if (cmp == 0) {
@@ -223,12 +233,12 @@ int distinctElements() {
     return Ints.saturatedCast(aggregateForEntries(Aggregate.DISTINCT));
   }
 
-  static int distinctElements(@NullableDecl AvlNode<?> node) {
+  static int distinctElements(@CheckForNull AvlNode<?> node) {
     return (node == null) ? 0 : node.distinctElements;
   }
 
   @Override
-  public int count(@NullableDecl Object element) {
+  public int count(@CheckForNull Object element) {
     try {
       @SuppressWarnings("unchecked")
       E e = (E) element;
@@ -244,7 +254,7 @@ public int count(@NullableDecl Object element) {
 
   @CanIgnoreReturnValue
   @Override
-  public int add(@NullableDecl E element, int occurrences) {
+  public int add(@ParametricNullness E element, int occurrences) {
     checkNonnegative(occurrences, "occurrences");
     if (occurrences == 0) {
       return count(element);
@@ -266,7 +276,7 @@ public int add(@NullableDecl E element, int occurrences) {
 
   @CanIgnoreReturnValue
   @Override
-  public int remove(@NullableDecl Object element, int occurrences) {
+  public int remove(@CheckForNull Object element, int occurrences) {
     checkNonnegative(occurrences, "occurrences");
     if (occurrences == 0) {
       return count(element);
@@ -290,7 +300,7 @@ public int remove(@NullableDecl Object element, int occurrences) {
 
   @CanIgnoreReturnValue
   @Override
-  public int setCount(@NullableDecl E element, int count) {
+  public int setCount(@ParametricNullness E element, int count) {
     checkNonnegative(count, "count");
     if (!range.contains(element)) {
       checkArgument(count == 0);
@@ -312,7 +322,7 @@ public int setCount(@NullableDecl E element, int count) {
 
   @CanIgnoreReturnValue
   @Override
-  public boolean setCount(@NullableDecl E element, int oldCount, int newCount) {
+  public boolean setCount(@ParametricNullness E element, int oldCount, int newCount) {
     checkNonnegative(newCount, "newCount");
     checkNonnegative(oldCount, "oldCount");
     checkArgument(range.contains(element));
@@ -338,8 +348,8 @@ public boolean setCount(@NullableDecl E element, int oldCount, int newCount) {
   public void clear() {
     if (!range.hasLowerBound() && !range.hasUpperBound()) {
       // We can do this in O(n) rather than removing one by one, which could force rebalancing.
-      for (AvlNode<E> current = header.succ; current != header; ) {
-        AvlNode<E> next = current.succ;
+      for (AvlNode<E> current = header.succ(); current != header; ) {
+        AvlNode<E> next = current.succ();
 
         current.elemCount = 0;
         // Also clear these fields so that one deleted Entry doesn't retain all elements.
@@ -361,6 +371,7 @@ public void clear() {
   private Entry<E> wrapEntry(final AvlNode<E> baseEntry) {
     return new Multisets.AbstractEntry<E>() {
       @Override
+      @ParametricNullness
       public E getElement() {
         return baseEntry.getElement();
       }
@@ -378,7 +389,7 @@ public int getCount() {
   }
 
   /** Returns the first node in the tree that is in range. */
-  @NullableDecl
+  @CheckForNull
   private AvlNode<E> firstNode() {
     AvlNode<E> root = rootReference.get();
     if (root == null) {
@@ -386,22 +397,23 @@ private AvlNode<E> firstNode() {
     }
     AvlNode<E> node;
     if (range.hasLowerBound()) {
-      E endpoint = range.getLowerEndpoint();
-      node = rootReference.get().ceiling(comparator(), endpoint);
+      // The cast is safe because of the hasLowerBound check.
+      E endpoint = uncheckedCastNullableTToT(range.getLowerEndpoint());
+      node = root.ceiling(comparator(), endpoint);
       if (node == null) {
         return null;
       }
       if (range.getLowerBoundType() == BoundType.OPEN
           && comparator().compare(endpoint, node.getElement()) == 0) {
-        node = node.succ;
+        node = node.succ();
       }
     } else {
-      node = header.succ;
+      node = header.succ();
     }
     return (node == header || !range.contains(node.getElement())) ? null : node;
   }
 
-  @NullableDecl
+  @CheckForNull
   private AvlNode<E> lastNode() {
     AvlNode<E> root = rootReference.get();
     if (root == null) {
@@ -409,17 +421,18 @@ private AvlNode<E> lastNode() {
     }
     AvlNode<E> node;
     if (range.hasUpperBound()) {
-      E endpoint = range.getUpperEndpoint();
-      node = rootReference.get().floor(comparator(), endpoint);
+      // The cast is safe because of the hasUpperBound check.
+      E endpoint = uncheckedCastNullableTToT(range.getUpperEndpoint());
+      node = root.floor(comparator(), endpoint);
       if (node == null) {
         return null;
       }
       if (range.getUpperBoundType() == BoundType.OPEN
           && comparator().compare(endpoint, node.getElement()) == 0) {
-        node = node.pred;
+        node = node.pred();
       }
     } else {
-      node = header.pred;
+      node = header.pred();
     }
     return (node == header || !range.contains(node.getElement())) ? null : node;
   }
@@ -432,8 +445,8 @@ Iterator<E> elementIterator() {
   @Override
   Iterator<Entry<E>> entryIterator() {
     return new Iterator<Entry<E>>() {
-      AvlNode<E> current = firstNode();
-      @NullableDecl Entry<E> prevEntry;
+      @CheckForNull AvlNode<E> current = firstNode();
+      @CheckForNull Entry<E> prevEntry;
 
       @Override
       public boolean hasNext() {
@@ -452,19 +465,20 @@ public Entry<E> next() {
         if (!hasNext()) {
           throw new NoSuchElementException();
         }
-        Entry<E> result = wrapEntry(current);
+        // requireNonNull is safe because current is only nulled out after iteration is complete.
+        Entry<E> result = wrapEntry(requireNonNull(current));
         prevEntry = result;
-        if (current.succ == header) {
+        if (current.succ() == header) {
           current = null;
         } else {
-          current = current.succ;
+          current = current.succ();
         }
         return result;
       }
 
       @Override
       public void remove() {
-        checkRemove(prevEntry != null);
+        checkState(prevEntry != null, "no calls to next() since the last call to remove()");
         setCount(prevEntry.getElement(), 0);
         prevEntry = null;
       }
@@ -474,8 +488,8 @@ public void remove() {
   @Override
   Iterator<Entry<E>> descendingEntryIterator() {
     return new Iterator<Entry<E>>() {
-      AvlNode<E> current = lastNode();
-      Entry<E> prevEntry = null;
+      @CheckForNull AvlNode<E> current = lastNode();
+      @CheckForNull Entry<E> prevEntry = null;
 
       @Override
       public boolean hasNext() {
@@ -494,19 +508,21 @@ public Entry<E> next() {
         if (!hasNext()) {
           throw new NoSuchElementException();
         }
+        // requireNonNull is safe because current is only nulled out after iteration is complete.
+        requireNonNull(current);
         Entry<E> result = wrapEntry(current);
         prevEntry = result;
-        if (current.pred == header) {
+        if (current.pred() == header) {
           current = null;
         } else {
-          current = current.pred;
+          current = current.pred();
         }
         return result;
       }
 
       @Override
       public void remove() {
-        checkRemove(prevEntry != null);
+        checkState(prevEntry != null, "no calls to next() since the last call to remove()");
         setCount(prevEntry.getElement(), 0);
         prevEntry = null;
       }
@@ -519,7 +535,7 @@ public Iterator<E> iterator() {
   }
 
   @Override
-  public SortedMultiset<E> headMultiset(@NullableDecl E upperBound, BoundType boundType) {
+  public SortedMultiset<E> headMultiset(@ParametricNullness E upperBound, BoundType boundType) {
     return new TreeMultiset<E>(
         rootReference,
         range.intersect(GeneralRange.upTo(comparator(), upperBound, boundType)),
@@ -527,7 +543,7 @@ public SortedMultiset<E> headMultiset(@NullableDecl E upperBound, BoundType boun
   }
 
   @Override
-  public SortedMultiset<E> tailMultiset(@NullableDecl E lowerBound, BoundType boundType) {
+  public SortedMultiset<E> tailMultiset(@ParametricNullness E lowerBound, BoundType boundType) {
     return new TreeMultiset<E>(
         rootReference,
         range.intersect(GeneralRange.downTo(comparator(), lowerBound, boundType)),
@@ -535,14 +551,14 @@ public SortedMultiset<E> tailMultiset(@NullableDecl E lowerBound, BoundType boun
   }
 
   private static final class Reference<T> {
-    @NullableDecl private T value;
+    @CheckForNull private T value;
 
-    @NullableDecl
+    @CheckForNull
     public T get() {
       return value;
     }
 
-    public void checkAndSet(@NullableDecl T expected, T newValue) {
+    public void checkAndSet(@CheckForNull T expected, @CheckForNull T newValue) {
       if (value != expected) {
         throw new ConcurrentModificationException();
       }
@@ -554,8 +570,18 @@ void clear() {
     }
   }
 
-  private static final class AvlNode<E> {
-    @NullableDecl private final E elem;
+  private static final class AvlNode<E extends @Nullable Object> {
+    /*
+     * For "normal" nodes, the type of this field is `E`, not `@Nullable E` (though note that E is a
+     * type that can include null, as in a TreeMultiset<@Nullable String>).
+     *
+     * For the header node, though, this field contains `null`, regardless of the type of the
+     * multiset.
+     *
+     * Most code that operates on an AvlNode never operates on the header node. Such code can access
+     * the elem field without a null check by calling getElement().
+     */
+    @CheckForNull private final E elem;
 
     // elemCount is 0 iff this node has been deleted.
     private int elemCount;
@@ -563,12 +589,23 @@ private static final class AvlNode<E> {
     private int distinctElements;
     private long totalCount;
     private int height;
-    @NullableDecl private AvlNode<E> left;
-    @NullableDecl private AvlNode<E> right;
-    @NullableDecl private AvlNode<E> pred;
-    @NullableDecl private AvlNode<E> succ;
-
-    AvlNode(@NullableDecl E elem, int elemCount) {
+    @CheckForNull private AvlNode<E> left;
+    @CheckForNull private AvlNode<E> right;
+    /*
+     * pred and succ are nullable after construction, but we always call successor() to initialize
+     * them immediately thereafter.
+     *
+     * They may be subsequently nulled out by TreeMultiset.clear(). I think that the only place that
+     * we can reference a node whose fields have been cleared is inside the iterator (and presumably
+     * only under concurrent modification).
+     *
+     * To access these fields when you know that they are not null, call the pred() and succ()
+     * methods, which perform null checks before returning the fields.
+     */
+    @CheckForNull private AvlNode<E> pred;
+    @CheckForNull private AvlNode<E> succ;
+
+    AvlNode(@ParametricNullness E elem, int elemCount) {
       checkArgument(elemCount > 0);
       this.elem = elem;
       this.elemCount = elemCount;
@@ -579,8 +616,24 @@ private static final class AvlNode<E> {
       this.right = null;
     }
 
-    public int count(Comparator<? super E> comparator, E e) {
-      int cmp = comparator.compare(e, elem);
+    /** Constructor for the header node. */
+    AvlNode() {
+      this.elem = null;
+      this.elemCount = 1;
+    }
+
+    // For discussion of pred() and succ(), see the comment on the pred and succ fields.
+
+    private AvlNode<E> pred() {
+      return requireNonNull(pred);
+    }
+
+    private AvlNode<E> succ() {
+      return requireNonNull(succ);
+    }
+
+    int count(Comparator<? super E> comparator, @ParametricNullness E e) {
+      int cmp = comparator.compare(e, getElement());
       if (cmp < 0) {
         return (left == null) ? 0 : left.count(comparator, e);
       } else if (cmp > 0) {
@@ -590,30 +643,31 @@ public int count(Comparator<? super E> comparator, E e) {
       }
     }
 
-    private AvlNode<E> addRightChild(E e, int count) {
+    private AvlNode<E> addRightChild(@ParametricNullness E e, int count) {
       right = new AvlNode<E>(e, count);
-      successor(this, right, succ);
+      successor(this, right, succ());
       height = Math.max(2, height);
       distinctElements++;
       totalCount += count;
       return this;
     }
 
-    private AvlNode<E> addLeftChild(E e, int count) {
+    private AvlNode<E> addLeftChild(@ParametricNullness E e, int count) {
       left = new AvlNode<E>(e, count);
-      successor(pred, left, this);
+      successor(pred(), left, this);
       height = Math.max(2, height);
       distinctElements++;
       totalCount += count;
       return this;
     }
 
-    AvlNode<E> add(Comparator<? super E> comparator, @NullableDecl E e, int count, int[] result) {
+    AvlNode<E> add(
+        Comparator<? super E> comparator, @ParametricNullness E e, int count, int[] result) {
       /*
        * It speeds things up considerably to unconditionally add count to totalCount here,
        * but that destroys failure atomicity in the case of count overflow. =(
        */
-      int cmp = comparator.compare(e, elem);
+      int cmp = comparator.compare(e, getElement());
       if (cmp < 0) {
         AvlNode<E> initLeft = left;
         if (initLeft == null) {
@@ -653,9 +707,10 @@ AvlNode<E> add(Comparator<? super E> comparator, @NullableDecl E e, int count, i
       return this;
     }
 
+    @CheckForNull
     AvlNode<E> remove(
-        Comparator<? super E> comparator, @NullableDecl E e, int count, int[] result) {
-      int cmp = comparator.compare(e, elem);
+        Comparator<? super E> comparator, @ParametricNullness E e, int count, int[] result) {
+      int cmp = comparator.compare(e, getElement());
       if (cmp < 0) {
         AvlNode<E> initLeft = left;
         if (initLeft == null) {
@@ -705,9 +760,10 @@ AvlNode<E> remove(
       }
     }
 
+    @CheckForNull
     AvlNode<E> setCount(
-        Comparator<? super E> comparator, @NullableDecl E e, int count, int[] result) {
-      int cmp = comparator.compare(e, elem);
+        Comparator<? super E> comparator, @ParametricNullness E e, int count, int[] result) {
+      int cmp = comparator.compare(e, getElement());
       if (cmp < 0) {
         AvlNode<E> initLeft = left;
         if (initLeft == null) {
@@ -754,13 +810,14 @@ AvlNode<E> setCount(
       return this;
     }
 
+    @CheckForNull
     AvlNode<E> setCount(
         Comparator<? super E> comparator,
-        @NullableDecl E e,
+        @ParametricNullness E e,
         int expectedCount,
         int newCount,
         int[] result) {
-      int cmp = comparator.compare(e, elem);
+      int cmp = comparator.compare(e, getElement());
       if (cmp < 0) {
         AvlNode<E> initLeft = left;
         if (initLeft == null) {
@@ -817,16 +874,17 @@ AvlNode<E> setCount(
       return this;
     }
 
+    @CheckForNull
     private AvlNode<E> deleteMe() {
       int oldElemCount = this.elemCount;
       this.elemCount = 0;
-      successor(pred, succ);
+      successor(pred(), succ());
       if (left == null) {
         return right;
       } else if (right == null) {
         return left;
       } else if (left.height >= right.height) {
-        AvlNode<E> newTop = pred;
+        AvlNode<E> newTop = pred();
         // newTop is the maximum node in my left subtree
         newTop.left = left.removeMax(newTop);
         newTop.right = right;
@@ -834,7 +892,7 @@ private AvlNode<E> deleteMe() {
         newTop.totalCount = totalCount - oldElemCount;
         return newTop.rebalance();
       } else {
-        AvlNode<E> newTop = succ;
+        AvlNode<E> newTop = succ();
         newTop.right = right.removeMin(newTop);
         newTop.left = left;
         newTop.distinctElements = distinctElements - 1;
@@ -844,6 +902,7 @@ private AvlNode<E> deleteMe() {
     }
 
     // Removes the minimum node from this subtree to be reused elsewhere
+    @CheckForNull
     private AvlNode<E> removeMin(AvlNode<E> node) {
       if (left == null) {
         return right;
@@ -856,6 +915,7 @@ private AvlNode<E> removeMin(AvlNode<E> node) {
     }
 
     // Removes the maximum node from this subtree to be reused elsewhere
+    @CheckForNull
     private AvlNode<E> removeMax(AvlNode<E> node) {
       if (right == null) {
         return left;
@@ -885,11 +945,15 @@ private void recompute() {
     private AvlNode<E> rebalance() {
       switch (balanceFactor()) {
         case -2:
+          // requireNonNull is safe because right must exist in order to get a negative factor.
+          requireNonNull(right);
           if (right.balanceFactor() > 0) {
             right = right.rotateRight();
           }
           return rotateLeft();
         case 2:
+          // requireNonNull is safe because left must exist in order to get a positive factor.
+          requireNonNull(left);
           if (left.balanceFactor() < 0) {
             left = left.rotateLeft();
           }
@@ -928,17 +992,17 @@ private AvlNode<E> rotateRight() {
       return newTop;
     }
 
-    private static long totalCount(@NullableDecl AvlNode<?> node) {
+    private static long totalCount(@CheckForNull AvlNode<?> node) {
       return (node == null) ? 0 : node.totalCount;
     }
 
-    private static int height(@NullableDecl AvlNode<?> node) {
+    private static int height(@CheckForNull AvlNode<?> node) {
       return (node == null) ? 0 : node.height;
     }
 
-    @NullableDecl
-    private AvlNode<E> ceiling(Comparator<? super E> comparator, E e) {
-      int cmp = comparator.compare(e, elem);
+    @CheckForNull
+    private AvlNode<E> ceiling(Comparator<? super E> comparator, @ParametricNullness E e) {
+      int cmp = comparator.compare(e, getElement());
       if (cmp < 0) {
         return (left == null) ? this : MoreObjects.firstNonNull(left.ceiling(comparator, e), this);
       } else if (cmp == 0) {
@@ -948,9 +1012,9 @@ private AvlNode<E> ceiling(Comparator<? super E> comparator, E e) {
       }
     }
 
-    @NullableDecl
-    private AvlNode<E> floor(Comparator<? super E> comparator, E e) {
-      int cmp = comparator.compare(e, elem);
+    @CheckForNull
+    private AvlNode<E> floor(Comparator<? super E> comparator, @ParametricNullness E e) {
+      int cmp = comparator.compare(e, getElement());
       if (cmp > 0) {
         return (right == null) ? this : MoreObjects.firstNonNull(right.floor(comparator, e), this);
       } else if (cmp == 0) {
@@ -960,8 +1024,10 @@ private AvlNode<E> floor(Comparator<? super E> comparator, E e) {
       }
     }
 
+    @ParametricNullness
     E getElement() {
-      return elem;
+      // For discussion of this cast, see the comment on the elem field.
+      return uncheckedCastNullableTToT(elem);
     }
 
     int getCount() {
@@ -974,12 +1040,13 @@ public String toString() {
     }
   }
 
-  private static <T> void successor(AvlNode<T> a, AvlNode<T> b) {
+  private static <T extends @Nullable Object> void successor(AvlNode<T> a, AvlNode<T> b) {
     a.succ = b;
     b.pred = a;
   }
 
-  private static <T> void successor(AvlNode<T> a, AvlNode<T> b, AvlNode<T> c) {
+  private static <T extends @Nullable Object> void successor(
+      AvlNode<T> a, AvlNode<T> b, AvlNode<T> c) {
     successor(a, b);
     successor(b, c);
   }
@@ -1012,7 +1079,7 @@ private void readObject(ObjectInputStream stream) throws IOException, ClassNotFo
         .set(this, GeneralRange.all(comparator));
     Serialization.getFieldSetter(TreeMultiset.class, "rootReference")
         .set(this, new Reference<AvlNode<E>>());
-    AvlNode<E> header = new AvlNode<E>(null, 1);
+    AvlNode<E> header = new AvlNode<>();
     Serialization.getFieldSetter(TreeMultiset.class, "header").set(this, header);
     successor(header, header);
     Serialization.populateMultiset(this, stream);
diff --git a/android/guava/src/com/google/common/collect/TreeRangeMap.java b/android/guava/src/com/google/common/collect/TreeRangeMap.java
index 8cb31b715453..0ce8e89551cf 100644
--- a/android/guava/src/com/google/common/collect/TreeRangeMap.java
+++ b/android/guava/src/com/google/common/collect/TreeRangeMap.java
@@ -21,6 +21,7 @@
 import static com.google.common.base.Predicates.compose;
 import static com.google.common.base.Predicates.in;
 import static com.google.common.base.Predicates.not;
+import static java.util.Objects.requireNonNull;
 
 import com.google.common.annotations.Beta;
 import com.google.common.annotations.GwtIncompatible;
@@ -37,7 +38,7 @@
 import java.util.NavigableMap;
 import java.util.NoSuchElementException;
 import java.util.Set;
-import org.checkerframework.checker.nullness.compatqual.NullableDecl;
+import javax.annotation.CheckForNull;
 
 /**
  * An implementation of {@code RangeMap} based on a {@code TreeMap}, supporting all optional
@@ -50,6 +51,7 @@
  */
 @Beta
 @GwtIncompatible // NavigableMap
+@ElementTypesAreNonnullByDefault
 public final class TreeRangeMap<K extends Comparable, V> implements RangeMap<K, V> {
 
   private final NavigableMap<Cut<K>, RangeMapEntry<K, V>> entriesByLowerBound;
@@ -100,14 +102,14 @@ Cut<K> getUpperBound() {
   }
 
   @Override
-  @NullableDecl
+  @CheckForNull
   public V get(K key) {
     Entry<Range<K>, V> entry = getEntry(key);
     return (entry == null) ? null : entry.getValue();
   }
 
   @Override
-  @NullableDecl
+  @CheckForNull
   public Entry<Range<K>, V> getEntry(K key) {
     Entry<Cut<K>, RangeMapEntry<K, V>> mapEntry =
         entriesByLowerBound.floorEntry(Cut.belowValue(key));
@@ -155,7 +157,7 @@ private Range<K> coalescedRange(Range<K> range, V value) {
 
   /** Returns the range that spans the given range and entry, if the entry can be coalesced. */
   private static <K extends Comparable, V> Range<K> coalesce(
-      Range<K> range, V value, @NullableDecl Entry<Cut<K>, RangeMapEntry<K, V>> entry) {
+      Range<K> range, V value, @CheckForNull Entry<Cut<K>, RangeMapEntry<K, V>> entry) {
     if (entry != null
         && entry.getValue().getKey().isConnected(range)
         && entry.getValue().getValue().equals(value)) {
@@ -180,7 +182,8 @@ public void clear() {
   public Range<K> span() {
     Entry<Cut<K>, RangeMapEntry<K, V>> firstEntry = entriesByLowerBound.firstEntry();
     Entry<Cut<K>, RangeMapEntry<K, V>> lastEntry = entriesByLowerBound.lastEntry();
-    if (firstEntry == null) {
+    // Either both are null or neither is, but we check both to satisfy the nullness checker.
+    if (firstEntry == null || lastEntry == null) {
       throw new NoSuchElementException();
     }
     return Range.create(
@@ -261,12 +264,13 @@ private final class AsMapOfRanges extends IteratorBasedAbstractMap<Range<K>, V>
     }
 
     @Override
-    public boolean containsKey(@NullableDecl Object key) {
+    public boolean containsKey(@CheckForNull Object key) {
       return get(key) != null;
     }
 
     @Override
-    public V get(@NullableDecl Object key) {
+    @CheckForNull
+    public V get(@CheckForNull Object key) {
       if (key instanceof Range) {
         Range<?> range = (Range<?>) key;
         RangeMapEntry<K, V> rangeMapEntry = entriesByLowerBound.get(range.lowerBound);
@@ -299,44 +303,45 @@ public RangeMap<K, V> subRangeMap(Range<K> subRange) {
 
   @SuppressWarnings("unchecked")
   private RangeMap<K, V> emptySubRangeMap() {
-    return EMPTY_SUB_RANGE_MAP;
+    return (RangeMap<K, V>) (RangeMap<?, ?>) EMPTY_SUB_RANGE_MAP;
   }
 
-  private static final RangeMap EMPTY_SUB_RANGE_MAP =
-      new RangeMap() {
+  @SuppressWarnings("ConstantCaseForConstants") // This RangeMap is immutable.
+  private static final RangeMap<Comparable<?>, Object> EMPTY_SUB_RANGE_MAP =
+      new RangeMap<Comparable<?>, Object>() {
         @Override
-        @NullableDecl
-        public Object get(Comparable key) {
+        @CheckForNull
+        public Object get(Comparable<?> key) {
           return null;
         }
 
         @Override
-        @NullableDecl
-        public Entry<Range, Object> getEntry(Comparable key) {
+        @CheckForNull
+        public Entry<Range<Comparable<?>>, Object> getEntry(Comparable<?> key) {
           return null;
         }
 
         @Override
-        public Range span() {
+        public Range<Comparable<?>> span() {
           throw new NoSuchElementException();
         }
 
         @Override
-        public void put(Range range, Object value) {
+        public void put(Range<Comparable<?>> range, Object value) {
           checkNotNull(range);
           throw new IllegalArgumentException(
               "Cannot insert range " + range + " into an empty subRangeMap");
         }
 
         @Override
-        public void putCoalescing(Range range, Object value) {
+        public void putCoalescing(Range<Comparable<?>> range, Object value) {
           checkNotNull(range);
           throw new IllegalArgumentException(
               "Cannot insert range " + range + " into an empty subRangeMap");
         }
 
         @Override
-        public void putAll(RangeMap rangeMap) {
+        public void putAll(RangeMap<Comparable<?>, Object> rangeMap) {
           if (!rangeMap.asMapOfRanges().isEmpty()) {
             throw new IllegalArgumentException(
                 "Cannot putAll(nonEmptyRangeMap) into an empty subRangeMap");
@@ -347,22 +352,22 @@ public void putAll(RangeMap rangeMap) {
         public void clear() {}
 
         @Override
-        public void remove(Range range) {
+        public void remove(Range<Comparable<?>> range) {
           checkNotNull(range);
         }
 
         @Override
-        public Map<Range, Object> asMapOfRanges() {
+        public Map<Range<Comparable<?>>, Object> asMapOfRanges() {
           return Collections.emptyMap();
         }
 
         @Override
-        public Map<Range, Object> asDescendingMapOfRanges() {
+        public Map<Range<Comparable<?>>, Object> asDescendingMapOfRanges() {
           return Collections.emptyMap();
         }
 
         @Override
-        public RangeMap subRangeMap(Range range) {
+        public RangeMap<Comparable<?>, Object> subRangeMap(Range<Comparable<?>> range) {
           checkNotNull(range);
           return this;
         }
@@ -377,13 +382,13 @@ private class SubRangeMap implements RangeMap<K, V> {
     }
 
     @Override
-    @NullableDecl
+    @CheckForNull
     public V get(K key) {
       return subRange.contains(key) ? TreeRangeMap.this.get(key) : null;
     }
 
     @Override
-    @NullableDecl
+    @CheckForNull
     public Entry<Range<K>, V> getEntry(K key) {
       if (subRange.contains(key)) {
         Entry<Range<K>, V> entry = TreeRangeMap.this.getEntry(key);
@@ -499,6 +504,7 @@ Iterator<Entry<Range<K>, V>> entryIterator() {
           return new AbstractIterator<Entry<Range<K>, V>>() {
 
             @Override
+            @CheckForNull
             protected Entry<Range<K>, V> computeNext() {
               if (backingItr.hasNext()) {
                 RangeMapEntry<K, V> entry = backingItr.next();
@@ -515,7 +521,7 @@ protected Entry<Range<K>, V> computeNext() {
     }
 
     @Override
-    public boolean equals(@NullableDecl Object o) {
+    public boolean equals(@CheckForNull Object o) {
       if (o instanceof RangeMap) {
         RangeMap<?, ?> rangeMap = (RangeMap<?, ?>) o;
         return asMapOfRanges().equals(rangeMap.asMapOfRanges());
@@ -536,12 +542,13 @@ public String toString() {
     class SubRangeMapAsMap extends AbstractMap<Range<K>, V> {
 
       @Override
-      public boolean containsKey(Object key) {
+      public boolean containsKey(@CheckForNull Object key) {
         return get(key) != null;
       }
 
       @Override
-      public V get(Object key) {
+      @CheckForNull
+      public V get(@CheckForNull Object key) {
         try {
           if (key instanceof Range) {
             @SuppressWarnings("unchecked") // we catch ClassCastExceptions
@@ -574,11 +581,13 @@ public V get(Object key) {
       }
 
       @Override
-      public V remove(Object key) {
+      @CheckForNull
+      public V remove(@CheckForNull Object key) {
         V value = get(key);
         if (value != null) {
-          @SuppressWarnings("unchecked") // it's definitely in the map, so safe
-          Range<K> range = (Range<K>) key;
+          // it's definitely in the map, so the cast and requireNonNull are safe
+          @SuppressWarnings("unchecked")
+          Range<K> range = (Range<K>) requireNonNull(key);
           TreeRangeMap.this.remove(range);
           return value;
         }
@@ -607,7 +616,7 @@ private boolean removeEntryIf(Predicate<? super Entry<Range<K>, V>> predicate) {
       public Set<Range<K>> keySet() {
         return new Maps.KeySet<Range<K>, V>(SubRangeMapAsMap.this) {
           @Override
-          public boolean remove(@NullableDecl Object o) {
+          public boolean remove(@CheckForNull Object o) {
             return SubRangeMapAsMap.this.remove(o) != null;
           }
 
@@ -660,6 +669,7 @@ Iterator<Entry<Range<K>, V>> entryIterator() {
         return new AbstractIterator<Entry<Range<K>, V>>() {
 
           @Override
+          @CheckForNull
           protected Entry<Range<K>, V> computeNext() {
             while (backingItr.hasNext()) {
               RangeMapEntry<K, V> entry = backingItr.next();
@@ -693,7 +703,7 @@ public boolean retainAll(Collection<?> c) {
   }
 
   @Override
-  public boolean equals(@NullableDecl Object o) {
+  public boolean equals(@CheckForNull Object o) {
     if (o instanceof RangeMap) {
       RangeMap<?, ?> rangeMap = (RangeMap<?, ?>) o;
       return asMapOfRanges().equals(rangeMap.asMapOfRanges());
diff --git a/android/guava/src/com/google/common/collect/TreeRangeSet.java b/android/guava/src/com/google/common/collect/TreeRangeSet.java
index c5a438a998ff..7ba71139eb96 100644
--- a/android/guava/src/com/google/common/collect/TreeRangeSet.java
+++ b/android/guava/src/com/google/common/collect/TreeRangeSet.java
@@ -30,7 +30,7 @@
 import java.util.NoSuchElementException;
 import java.util.Set;
 import java.util.TreeMap;
-import org.checkerframework.checker.nullness.compatqual.NullableDecl;
+import javax.annotation.CheckForNull;
 
 /**
  * An implementation of {@link RangeSet} backed by a {@link TreeMap}.
@@ -40,6 +40,7 @@
  */
 @Beta
 @GwtIncompatible // uses NavigableMap
+@ElementTypesAreNonnullByDefault
 public class TreeRangeSet<C extends Comparable<?>> extends AbstractRangeSet<C>
     implements Serializable {
 
@@ -47,7 +48,7 @@ public class TreeRangeSet<C extends Comparable<?>> extends AbstractRangeSet<C>
 
   /** Creates an empty {@code TreeRangeSet} instance. */
   public static <C extends Comparable<?>> TreeRangeSet<C> create() {
-    return new TreeRangeSet<C>(new TreeMap<Cut<C>, Range<C>>());
+    return new TreeRangeSet<>(new TreeMap<Cut<C>, Range<C>>());
   }
 
   /** Returns a {@code TreeRangeSet} initialized with the ranges in the specified range set. */
@@ -76,8 +77,8 @@ private TreeRangeSet(NavigableMap<Cut<C>, Range<C>> rangesByLowerCut) {
     this.rangesByLowerBound = rangesByLowerCut;
   }
 
-  @NullableDecl private transient Set<Range<C>> asRanges;
-  @NullableDecl private transient Set<Range<C>> asDescendingSetOfRanges;
+  @CheckForNull private transient Set<Range<C>> asRanges;
+  @CheckForNull private transient Set<Range<C>> asDescendingSetOfRanges;
 
   @Override
   public Set<Range<C>> asRanges() {
@@ -112,13 +113,13 @@ public int hashCode() {
     }
 
     @Override
-    public boolean equals(@NullableDecl Object o) {
+    public boolean equals(@CheckForNull Object o) {
       return Sets.equalsImpl(this, o);
     }
   }
 
   @Override
-  @NullableDecl
+  @CheckForNull
   public Range<C> rangeContaining(C value) {
     checkNotNull(value);
     Entry<Cut<C>, Range<C>> floorEntry = rangesByLowerBound.floorEntry(Cut.belowValue(value));
@@ -152,7 +153,7 @@ public boolean encloses(Range<C> range) {
     return floorEntry != null && floorEntry.getValue().encloses(range);
   }
 
-  @NullableDecl
+  @CheckForNull
   private Range<C> rangeEnclosing(Range<C> range) {
     checkNotNull(range);
     Entry<Cut<C>, Range<C>> floorEntry = rangesByLowerBound.floorEntry(range.lowerBound);
@@ -165,7 +166,11 @@ private Range<C> rangeEnclosing(Range<C> range) {
   public Range<C> span() {
     Entry<Cut<C>, Range<C>> firstEntry = rangesByLowerBound.firstEntry();
     Entry<Cut<C>, Range<C>> lastEntry = rangesByLowerBound.lastEntry();
-    if (firstEntry == null) {
+    if (firstEntry == null || lastEntry == null) {
+      /*
+       * Either both are null or neither is: Either the set is empty, or it's not. But we check both
+       * to make the nullness checker happy.
+       */
       throw new NoSuchElementException();
     }
     return Range.create(firstEntry.getValue().lowerBound, lastEntry.getValue().upperBound);
@@ -269,7 +274,7 @@ private void replaceRangeWithSameLowerBound(Range<C> range) {
     }
   }
 
-  @NullableDecl private transient RangeSet<C> complement;
+  @CheckForNull private transient RangeSet<C> complement;
 
   @Override
   public RangeSet<C> complement() {
@@ -301,7 +306,7 @@ private RangesByUpperBound(
 
     private NavigableMap<Cut<C>, Range<C>> subMap(Range<Cut<C>> window) {
       if (window.isConnected(upperBoundWindow)) {
-        return new RangesByUpperBound<C>(rangesByLowerBound, window.intersection(upperBoundWindow));
+        return new RangesByUpperBound<>(rangesByLowerBound, window.intersection(upperBoundWindow));
       } else {
         return ImmutableSortedMap.of();
       }
@@ -332,12 +337,13 @@ public Comparator<? super Cut<C>> comparator() {
     }
 
     @Override
-    public boolean containsKey(@NullableDecl Object key) {
+    public boolean containsKey(@CheckForNull Object key) {
       return get(key) != null;
     }
 
     @Override
-    public Range<C> get(@NullableDecl Object key) {
+    @CheckForNull
+    public Range<C> get(@CheckForNull Object key) {
       if (key instanceof Cut) {
         try {
           @SuppressWarnings("unchecked") // we catch CCEs
@@ -362,7 +368,7 @@ Iterator<Entry<Cut<C>, Range<C>>> entryIterator() {
        * We want to start the iteration at the first range where the upper bound is in
        * upperBoundWindow.
        */
-      final Iterator<Range<C>> backingItr;
+      Iterator<Range<C>> backingItr;
       if (!upperBoundWindow.hasLowerBound()) {
         backingItr = rangesByLowerBound.values().iterator();
       } else {
@@ -382,6 +388,7 @@ Iterator<Entry<Cut<C>, Range<C>>> entryIterator() {
       }
       return new AbstractIterator<Entry<Cut<C>, Range<C>>>() {
         @Override
+        @CheckForNull
         protected Entry<Cut<C>, Range<C>> computeNext() {
           if (!backingItr.hasNext()) {
             return endOfData();
@@ -408,13 +415,14 @@ Iterator<Entry<Cut<C>, Range<C>>> descendingEntryIterator() {
       } else {
         candidates = rangesByLowerBound.descendingMap().values();
       }
-      final PeekingIterator<Range<C>> backingItr = Iterators.peekingIterator(candidates.iterator());
+      PeekingIterator<Range<C>> backingItr = Iterators.peekingIterator(candidates.iterator());
       if (backingItr.hasNext()
           && upperBoundWindow.upperBound.isLessThan(backingItr.peek().upperBound)) {
         backingItr.next();
       }
       return new AbstractIterator<Entry<Cut<C>, Range<C>>>() {
         @Override
+        @CheckForNull
         protected Entry<Cut<C>, Range<C>> computeNext() {
           if (!backingItr.hasNext()) {
             return endOfData();
@@ -462,7 +470,7 @@ private static final class ComplementRangesByLowerBound<C extends Comparable<?>>
     private ComplementRangesByLowerBound(
         NavigableMap<Cut<C>, Range<C>> positiveRangesByLowerBound, Range<Cut<C>> window) {
       this.positiveRangesByLowerBound = positiveRangesByLowerBound;
-      this.positiveRangesByUpperBound = new RangesByUpperBound<C>(positiveRangesByLowerBound);
+      this.positiveRangesByUpperBound = new RangesByUpperBound<>(positiveRangesByLowerBound);
       this.complementLowerBoundWindow = window;
     }
 
@@ -471,7 +479,7 @@ private NavigableMap<Cut<C>, Range<C>> subMap(Range<Cut<C>> subWindow) {
         return ImmutableSortedMap.of();
       } else {
         subWindow = subWindow.intersection(complementLowerBoundWindow);
-        return new ComplementRangesByLowerBound<C>(positiveRangesByLowerBound, subWindow);
+        return new ComplementRangesByLowerBound<>(positiveRangesByLowerBound, subWindow);
       }
     }
 
@@ -521,9 +529,8 @@ Iterator<Entry<Cut<C>, Range<C>>> entryIterator() {
       } else {
         positiveRanges = positiveRangesByUpperBound.values();
       }
-      final PeekingIterator<Range<C>> positiveItr =
-          Iterators.peekingIterator(positiveRanges.iterator());
-      final Cut<C> firstComplementRangeLowerBound;
+      PeekingIterator<Range<C>> positiveItr = Iterators.peekingIterator(positiveRanges.iterator());
+      Cut<C> firstComplementRangeLowerBound;
       if (complementLowerBoundWindow.contains(Cut.<C>belowAll())
           && (!positiveItr.hasNext() || positiveItr.peek().lowerBound != Cut.<C>belowAll())) {
         firstComplementRangeLowerBound = Cut.belowAll();
@@ -536,6 +543,7 @@ Iterator<Entry<Cut<C>, Range<C>>> entryIterator() {
         Cut<C> nextComplementRangeLowerBound = firstComplementRangeLowerBound;
 
         @Override
+        @CheckForNull
         protected Entry<Cut<C>, Range<C>> computeNext() {
           if (complementLowerBoundWindow.upperBound.isLessThan(nextComplementRangeLowerBound)
               || nextComplementRangeLowerBound == Cut.<C>aboveAll()) {
@@ -572,7 +580,7 @@ Iterator<Entry<Cut<C>, Range<C>>> descendingEntryIterator() {
       boolean inclusive =
           complementLowerBoundWindow.hasUpperBound()
               && complementLowerBoundWindow.upperBoundType() == BoundType.CLOSED;
-      final PeekingIterator<Range<C>> positiveItr =
+      PeekingIterator<Range<C>> positiveItr =
           Iterators.peekingIterator(
               positiveRangesByUpperBound
                   .headMap(startingPoint, inclusive)
@@ -591,12 +599,12 @@ Iterator<Entry<Cut<C>, Range<C>>> descendingEntryIterator() {
       } else {
         cut = positiveRangesByLowerBound.higherKey(Cut.<C>belowAll());
       }
-      final Cut<C> firstComplementRangeUpperBound =
-          MoreObjects.firstNonNull(cut, Cut.<C>aboveAll());
+      Cut<C> firstComplementRangeUpperBound = MoreObjects.firstNonNull(cut, Cut.<C>aboveAll());
       return new AbstractIterator<Entry<Cut<C>, Range<C>>>() {
         Cut<C> nextComplementRangeUpperBound = firstComplementRangeUpperBound;
 
         @Override
+        @CheckForNull
         protected Entry<Cut<C>, Range<C>> computeNext() {
           if (nextComplementRangeUpperBound == Cut.<C>belowAll()) {
             return endOfData();
@@ -624,8 +632,8 @@ public int size() {
     }
 
     @Override
-    @NullableDecl
-    public Range<C> get(Object key) {
+    @CheckForNull
+    public Range<C> get(@CheckForNull Object key) {
       if (key instanceof Cut) {
         try {
           @SuppressWarnings("unchecked")
@@ -643,7 +651,7 @@ public Range<C> get(Object key) {
     }
 
     @Override
-    public boolean containsKey(Object key) {
+    public boolean containsKey(@CheckForNull Object key) {
       return get(key) != null;
     }
   }
@@ -698,14 +706,14 @@ private SubRangeSetRangesByLowerBound(
       this.lowerBoundWindow = checkNotNull(lowerBoundWindow);
       this.restriction = checkNotNull(restriction);
       this.rangesByLowerBound = checkNotNull(rangesByLowerBound);
-      this.rangesByUpperBound = new RangesByUpperBound<C>(rangesByLowerBound);
+      this.rangesByUpperBound = new RangesByUpperBound<>(rangesByLowerBound);
     }
 
     private NavigableMap<Cut<C>, Range<C>> subMap(Range<Cut<C>> window) {
       if (!window.isConnected(lowerBoundWindow)) {
         return ImmutableSortedMap.of();
       } else {
-        return new SubRangeSetRangesByLowerBound<C>(
+        return new SubRangeSetRangesByLowerBound<>(
             lowerBoundWindow.intersection(window), restriction, rangesByLowerBound);
       }
     }
@@ -737,13 +745,13 @@ public Comparator<? super Cut<C>> comparator() {
     }
 
     @Override
-    public boolean containsKey(@NullableDecl Object key) {
+    public boolean containsKey(@CheckForNull Object key) {
       return get(key) != null;
     }
 
     @Override
-    @NullableDecl
-    public Range<C> get(@NullableDecl Object key) {
+    @CheckForNull
+    public Range<C> get(@CheckForNull Object key) {
       if (key instanceof Cut) {
         try {
           @SuppressWarnings("unchecked") // we catch CCE's
@@ -776,7 +784,7 @@ Iterator<Entry<Cut<C>, Range<C>>> entryIterator() {
       if (restriction.isEmpty()) {
         return Iterators.emptyIterator();
       }
-      final Iterator<Range<C>> completeRangeItr;
+      Iterator<Range<C>> completeRangeItr;
       if (lowerBoundWindow.upperBound.isLessThan(restriction.lowerBound)) {
         return Iterators.emptyIterator();
       } else if (lowerBoundWindow.lowerBound.isLessThan(restriction.lowerBound)) {
@@ -793,11 +801,12 @@ Iterator<Entry<Cut<C>, Range<C>>> entryIterator() {
                 .values()
                 .iterator();
       }
-      final Cut<Cut<C>> upperBoundOnLowerBounds =
+      Cut<Cut<C>> upperBoundOnLowerBounds =
           Ordering.natural()
               .min(lowerBoundWindow.upperBound, Cut.belowValue(restriction.upperBound));
       return new AbstractIterator<Entry<Cut<C>, Range<C>>>() {
         @Override
+        @CheckForNull
         protected Entry<Cut<C>, Range<C>> computeNext() {
           if (!completeRangeItr.hasNext()) {
             return endOfData();
@@ -821,7 +830,7 @@ Iterator<Entry<Cut<C>, Range<C>>> descendingEntryIterator() {
       Cut<Cut<C>> upperBoundOnLowerBounds =
           Ordering.natural()
               .min(lowerBoundWindow.upperBound, Cut.belowValue(restriction.upperBound));
-      final Iterator<Range<C>> completeRangeItr =
+      Iterator<Range<C>> completeRangeItr =
           rangesByLowerBound
               .headMap(
                   upperBoundOnLowerBounds.endpoint(),
@@ -831,6 +840,7 @@ Iterator<Entry<Cut<C>, Range<C>>> descendingEntryIterator() {
               .iterator();
       return new AbstractIterator<Entry<Cut<C>, Range<C>>>() {
         @Override
+        @CheckForNull
         protected Entry<Cut<C>, Range<C>> computeNext() {
           if (!completeRangeItr.hasNext()) {
             return endOfData();
@@ -880,7 +890,7 @@ public boolean encloses(Range<C> range) {
     }
 
     @Override
-    @NullableDecl
+    @CheckForNull
     public Range<C> rangeContaining(C value) {
       if (!restriction.contains(value)) {
         return null;
diff --git a/android/guava/src/com/google/common/collect/TreeTraverser.java b/android/guava/src/com/google/common/collect/TreeTraverser.java
index 550cdfc72efb..73f8154f2a79 100644
--- a/android/guava/src/com/google/common/collect/TreeTraverser.java
+++ b/android/guava/src/com/google/common/collect/TreeTraverser.java
@@ -25,6 +25,7 @@
 import java.util.Deque;
 import java.util.Iterator;
 import java.util.Queue;
+import javax.annotation.CheckForNull;
 
 /**
  * Views elements of a type {@code T} as nodes in a tree, and provides methods to traverse the trees
@@ -73,6 +74,7 @@
 @Deprecated
 @Beta
 @GwtCompatible
+@ElementTypesAreNonnullByDefault
 public abstract class TreeTraverser<T> {
 
   /**
@@ -197,6 +199,7 @@ private final class PostOrderIterator extends AbstractIterator<T> {
     }
 
     @Override
+    @CheckForNull
     protected T computeNext() {
       while (!stack.isEmpty()) {
         PostOrderNode<T> top = stack.getLast();
diff --git a/android/guava/src/com/google/common/collect/UnmodifiableIterator.java b/android/guava/src/com/google/common/collect/UnmodifiableIterator.java
index 71196dcb3e7d..03e52aa2037d 100644
--- a/android/guava/src/com/google/common/collect/UnmodifiableIterator.java
+++ b/android/guava/src/com/google/common/collect/UnmodifiableIterator.java
@@ -19,6 +19,7 @@
 import com.google.common.annotations.GwtCompatible;
 import com.google.errorprone.annotations.DoNotCall;
 import java.util.Iterator;
+import org.checkerframework.checker.nullness.qual.Nullable;
 
 /**
  * An iterator that does not support {@link #remove}.
@@ -31,7 +32,8 @@
  * @since 2.0
  */
 @GwtCompatible
-public abstract class UnmodifiableIterator<E> implements Iterator<E> {
+@ElementTypesAreNonnullByDefault
+public abstract class UnmodifiableIterator<E extends @Nullable Object> implements Iterator<E> {
   /** Constructor for use by subclasses. */
   protected UnmodifiableIterator() {}
 
diff --git a/android/guava/src/com/google/common/collect/UnmodifiableListIterator.java b/android/guava/src/com/google/common/collect/UnmodifiableListIterator.java
index 4369ea102a3b..f3d3b921b7dc 100644
--- a/android/guava/src/com/google/common/collect/UnmodifiableListIterator.java
+++ b/android/guava/src/com/google/common/collect/UnmodifiableListIterator.java
@@ -19,6 +19,7 @@
 import com.google.common.annotations.GwtCompatible;
 import com.google.errorprone.annotations.DoNotCall;
 import java.util.ListIterator;
+import org.checkerframework.checker.nullness.qual.Nullable;
 
 /**
  * A list iterator that does not support {@link #remove}, {@link #add}, or {@link #set}.
@@ -27,8 +28,9 @@
  * @author Louis Wasserman
  */
 @GwtCompatible
-public abstract class UnmodifiableListIterator<E> extends UnmodifiableIterator<E>
-    implements ListIterator<E> {
+@ElementTypesAreNonnullByDefault
+public abstract class UnmodifiableListIterator<E extends @Nullable Object>
+    extends UnmodifiableIterator<E> implements ListIterator<E> {
   /** Constructor for use by subclasses. */
   protected UnmodifiableListIterator() {}
 
@@ -41,7 +43,7 @@ protected UnmodifiableListIterator() {}
   @Deprecated
   @Override
   @DoNotCall("Always throws UnsupportedOperationException")
-  public final void add(E e) {
+  public final void add(@ParametricNullness E e) {
     throw new UnsupportedOperationException();
   }
 
@@ -54,7 +56,7 @@ public final void add(E e) {
   @Deprecated
   @Override
   @DoNotCall("Always throws UnsupportedOperationException")
-  public final void set(E e) {
+  public final void set(@ParametricNullness E e) {
     throw new UnsupportedOperationException();
   }
 }
diff --git a/android/guava/src/com/google/common/collect/UnmodifiableSortedMultiset.java b/android/guava/src/com/google/common/collect/UnmodifiableSortedMultiset.java
index 20286afe1156..31f3c7197776 100644
--- a/android/guava/src/com/google/common/collect/UnmodifiableSortedMultiset.java
+++ b/android/guava/src/com/google/common/collect/UnmodifiableSortedMultiset.java
@@ -20,7 +20,8 @@
 import com.google.common.collect.Multisets.UnmodifiableMultiset;
 import java.util.Comparator;
 import java.util.NavigableSet;
-import org.checkerframework.checker.nullness.compatqual.NullableDecl;
+import javax.annotation.CheckForNull;
+import org.checkerframework.checker.nullness.qual.Nullable;
 
 /**
  * Implementation of {@link Multisets#unmodifiableSortedMultiset(SortedMultiset)}, split out into
@@ -30,7 +31,8 @@
  * @author Louis Wasserman
  */
 @GwtCompatible(emulated = true)
-final class UnmodifiableSortedMultiset<E> extends UnmodifiableMultiset<E>
+@ElementTypesAreNonnullByDefault
+final class UnmodifiableSortedMultiset<E extends @Nullable Object> extends UnmodifiableMultiset<E>
     implements SortedMultiset<E> {
   UnmodifiableSortedMultiset(SortedMultiset<E> delegate) {
     super(delegate);
@@ -56,13 +58,13 @@ public NavigableSet<E> elementSet() {
     return (NavigableSet<E>) super.elementSet();
   }
 
-  @NullableDecl private transient UnmodifiableSortedMultiset<E> descendingMultiset;
+  @CheckForNull private transient UnmodifiableSortedMultiset<E> descendingMultiset;
 
   @Override
   public SortedMultiset<E> descendingMultiset() {
     UnmodifiableSortedMultiset<E> result = descendingMultiset;
     if (result == null) {
-      result = new UnmodifiableSortedMultiset<E>(delegate().descendingMultiset());
+      result = new UnmodifiableSortedMultiset<>(delegate().descendingMultiset());
       result.descendingMultiset = this;
       return descendingMultiset = result;
     }
@@ -70,39 +72,46 @@ public SortedMultiset<E> descendingMultiset() {
   }
 
   @Override
+  @CheckForNull
   public Entry<E> firstEntry() {
     return delegate().firstEntry();
   }
 
   @Override
+  @CheckForNull
   public Entry<E> lastEntry() {
     return delegate().lastEntry();
   }
 
   @Override
+  @CheckForNull
   public Entry<E> pollFirstEntry() {
     throw new UnsupportedOperationException();
   }
 
   @Override
+  @CheckForNull
   public Entry<E> pollLastEntry() {
     throw new UnsupportedOperationException();
   }
 
   @Override
-  public SortedMultiset<E> headMultiset(E upperBound, BoundType boundType) {
+  public SortedMultiset<E> headMultiset(@ParametricNullness E upperBound, BoundType boundType) {
     return Multisets.unmodifiableSortedMultiset(delegate().headMultiset(upperBound, boundType));
   }
 
   @Override
   public SortedMultiset<E> subMultiset(
-      E lowerBound, BoundType lowerBoundType, E upperBound, BoundType upperBoundType) {
+      @ParametricNullness E lowerBound,
+      BoundType lowerBoundType,
+      @ParametricNullness E upperBound,
+      BoundType upperBoundType) {
     return Multisets.unmodifiableSortedMultiset(
         delegate().subMultiset(lowerBound, lowerBoundType, upperBound, upperBoundType));
   }
 
   @Override
-  public SortedMultiset<E> tailMultiset(E lowerBound, BoundType boundType) {
+  public SortedMultiset<E> tailMultiset(@ParametricNullness E lowerBound, BoundType boundType) {
     return Multisets.unmodifiableSortedMultiset(delegate().tailMultiset(lowerBound, boundType));
   }
 
diff --git a/android/guava/src/com/google/common/collect/UsingToStringOrdering.java b/android/guava/src/com/google/common/collect/UsingToStringOrdering.java
index 3167946b1582..3443b43e7223 100644
--- a/android/guava/src/com/google/common/collect/UsingToStringOrdering.java
+++ b/android/guava/src/com/google/common/collect/UsingToStringOrdering.java
@@ -21,6 +21,7 @@
 
 /** An ordering that uses the natural order of the string representation of the values. */
 @GwtCompatible(serializable = true)
+@ElementTypesAreNonnullByDefault
 final class UsingToStringOrdering extends Ordering<Object> implements Serializable {
   static final UsingToStringOrdering INSTANCE = new UsingToStringOrdering();
 
diff --git a/android/guava/src/com/google/common/escape/ArrayBasedCharEscaper.java b/android/guava/src/com/google/common/escape/ArrayBasedCharEscaper.java
index 91e48e6c9c6b..dbe6e3568035 100644
--- a/android/guava/src/com/google/common/escape/ArrayBasedCharEscaper.java
+++ b/android/guava/src/com/google/common/escape/ArrayBasedCharEscaper.java
@@ -16,9 +16,9 @@
 
 import static com.google.common.base.Preconditions.checkNotNull;
 
-import com.google.common.annotations.Beta;
 import com.google.common.annotations.GwtCompatible;
 import java.util.Map;
+import javax.annotation.CheckForNull;
 
 /**
  * A {@link CharEscaper} that uses an array to quickly look up replacement characters for a given
@@ -40,8 +40,8 @@
  * @author David Beaumont
  * @since 15.0
  */
-@Beta
 @GwtCompatible
+@ElementTypesAreNonnullByDefault
 public abstract class ArrayBasedCharEscaper extends CharEscaper {
   // The replacement array (see ArrayBasedEscaperMap).
   private final char[][] replacements;
@@ -117,8 +117,11 @@ public final String escape(String s) {
    * Escapes a single character using the replacement array and safe range values. If the given
    * character does not have an explicit replacement and lies outside the safe range then {@link
    * #escapeUnsafe} is called.
+   *
+   * @return the replacement characters, or {@code null} if no escaping was required
    */
   @Override
+  @CheckForNull
   protected final char[] escape(char c) {
     if (c < replacementsLength) {
       char[] chars = replacements[c];
@@ -145,5 +148,6 @@ protected final char[] escape(char c) {
    * @return the replacement characters, or {@code null} if no escaping was required
    */
   // TODO(dbeaumont,cpovirk): Rename this something better once refactoring done
+  @CheckForNull
   protected abstract char[] escapeUnsafe(char c);
 }
diff --git a/android/guava/src/com/google/common/escape/ArrayBasedEscaperMap.java b/android/guava/src/com/google/common/escape/ArrayBasedEscaperMap.java
index 400c3b13546e..efc77d058bb4 100644
--- a/android/guava/src/com/google/common/escape/ArrayBasedEscaperMap.java
+++ b/android/guava/src/com/google/common/escape/ArrayBasedEscaperMap.java
@@ -16,7 +16,6 @@
 
 import static com.google.common.base.Preconditions.checkNotNull;
 
-import com.google.common.annotations.Beta;
 import com.google.common.annotations.GwtCompatible;
 import com.google.common.annotations.VisibleForTesting;
 import java.util.Collections;
@@ -36,8 +35,8 @@
  * @author David Beaumont
  * @since 15.0
  */
-@Beta
 @GwtCompatible
+@ElementTypesAreNonnullByDefault
 public final class ArrayBasedEscaperMap {
   /**
    * Returns a new ArrayBasedEscaperMap for creating ArrayBasedCharEscaper or
@@ -73,7 +72,7 @@ static char[][] createReplacementArray(Map<Character, String> map) {
     }
     char max = Collections.max(map.keySet());
     char[][] replacements = new char[max + 1][];
-    for (char c : map.keySet()) {
+    for (Character c : map.keySet()) {
       replacements[c] = map.get(c).toCharArray();
     }
     return replacements;
diff --git a/android/guava/src/com/google/common/escape/ArrayBasedUnicodeEscaper.java b/android/guava/src/com/google/common/escape/ArrayBasedUnicodeEscaper.java
index 46057e95eb11..355faaa10d06 100644
--- a/android/guava/src/com/google/common/escape/ArrayBasedUnicodeEscaper.java
+++ b/android/guava/src/com/google/common/escape/ArrayBasedUnicodeEscaper.java
@@ -16,10 +16,10 @@
 
 import static com.google.common.base.Preconditions.checkNotNull;
 
-import com.google.common.annotations.Beta;
 import com.google.common.annotations.GwtCompatible;
 import java.util.Map;
-import org.checkerframework.checker.nullness.compatqual.NullableDecl;
+import javax.annotation.CheckForNull;
+import org.checkerframework.checker.nullness.qual.Nullable;
 
 /**
  * A {@link UnicodeEscaper} that uses an array to quickly look up replacement characters for a given
@@ -40,8 +40,8 @@
  * @author David Beaumont
  * @since 15.0
  */
-@Beta
 @GwtCompatible
+@ElementTypesAreNonnullByDefault
 public abstract class ArrayBasedUnicodeEscaper extends UnicodeEscaper {
   // The replacement array (see ArrayBasedEscaperMap).
   private final char[][] replacements;
@@ -73,7 +73,7 @@ protected ArrayBasedUnicodeEscaper(
       Map<Character, String> replacementMap,
       int safeMin,
       int safeMax,
-      @NullableDecl String unsafeReplacement) {
+      @Nullable String unsafeReplacement) {
     this(ArrayBasedEscaperMap.create(replacementMap), safeMin, safeMax, unsafeReplacement);
   }
 
@@ -96,7 +96,7 @@ protected ArrayBasedUnicodeEscaper(
       ArrayBasedEscaperMap escaperMap,
       int safeMin,
       int safeMax,
-      @NullableDecl String unsafeReplacement) {
+      @Nullable String unsafeReplacement) {
     checkNotNull(escaperMap); // GWT specific check (do not optimize)
     this.replacements = escaperMap.getReplacementArray();
     this.replacementsLength = replacements.length;
@@ -157,8 +157,11 @@ public final String escape(String s) {
    * Escapes a single Unicode code point using the replacement array and safe range values. If the
    * given character does not have an explicit replacement and lies outside the safe range then
    * {@link #escapeUnsafe} is called.
+   *
+   * @return the replacement characters, or {@code null} if no escaping was required
    */
   @Override
+  @CheckForNull
   protected final char[] escape(int cp) {
     if (cp < replacementsLength) {
       char[] chars = replacements[cp];
@@ -199,5 +202,6 @@ protected final int nextEscapeIndex(CharSequence csq, int index, int end) {
    * @param cp the Unicode code point to escape
    * @return the replacement characters, or {@code null} if no escaping was required
    */
+  @CheckForNull
   protected abstract char[] escapeUnsafe(int cp);
 }
diff --git a/android/guava/src/com/google/common/escape/CharEscaper.java b/android/guava/src/com/google/common/escape/CharEscaper.java
index b8ffee3a978a..136240ec639e 100644
--- a/android/guava/src/com/google/common/escape/CharEscaper.java
+++ b/android/guava/src/com/google/common/escape/CharEscaper.java
@@ -16,8 +16,8 @@
 
 import static com.google.common.base.Preconditions.checkNotNull;
 
-import com.google.common.annotations.Beta;
 import com.google.common.annotations.GwtCompatible;
+import javax.annotation.CheckForNull;
 
 /**
  * An object that converts literal text into a format safe for inclusion in a particular context
@@ -39,8 +39,8 @@
  * @author Sven Mawson
  * @since 15.0
  */
-@Beta
 @GwtCompatible
+@ElementTypesAreNonnullByDefault
 public abstract class CharEscaper extends Escaper {
   /** Constructor for use by subclasses. */
   protected CharEscaper() {}
@@ -80,6 +80,7 @@ public String escape(String string) {
    * @param c the character to escape if necessary
    * @return the replacement characters, or {@code null} if no escaping was needed
    */
+  @CheckForNull
   protected abstract char[] escape(char c);
 
   /**
diff --git a/android/guava/src/com/google/common/escape/CharEscaperBuilder.java b/android/guava/src/com/google/common/escape/CharEscaperBuilder.java
index dba855f36b8a..97528cb569c1 100644
--- a/android/guava/src/com/google/common/escape/CharEscaperBuilder.java
+++ b/android/guava/src/com/google/common/escape/CharEscaperBuilder.java
@@ -16,12 +16,13 @@
 
 import static com.google.common.base.Preconditions.checkNotNull;
 
-import com.google.common.annotations.Beta;
 import com.google.common.annotations.GwtCompatible;
 import com.google.errorprone.annotations.CanIgnoreReturnValue;
 import java.util.HashMap;
 import java.util.Map;
 import java.util.Map.Entry;
+import javax.annotation.CheckForNull;
+import org.checkerframework.checker.nullness.qual.Nullable;
 
 /**
  * Simple helper class to build a "sparse" array of objects based on the indexes that were added to
@@ -32,18 +33,18 @@
  * @author Sven Mawson
  * @since 15.0
  */
-@Beta
 @GwtCompatible
+@ElementTypesAreNonnullByDefault
 public final class CharEscaperBuilder {
   /**
    * Simple decorator that turns an array of replacement char[]s into a CharEscaper, this results in
    * a very fast escape method.
    */
   private static class CharArrayDecorator extends CharEscaper {
-    private final char[][] replacements;
+    private final char[] @Nullable [] replacements;
     private final int replaceLength;
 
-    CharArrayDecorator(char[][] replacements) {
+    CharArrayDecorator(char[] @Nullable [] replacements) {
       this.replacements = replacements;
       this.replaceLength = replacements.length;
     }
@@ -65,6 +66,7 @@ public String escape(String s) {
     }
 
     @Override
+    @CheckForNull
     protected char[] escape(char c) {
       return c < replaceLength ? replacements[c] : null;
     }
@@ -108,7 +110,7 @@ public CharEscaperBuilder addEscapes(char[] cs, String r) {
    *
    * @return a "sparse" array that holds the replacement mappings.
    */
-  public char[][] toArray() {
+  public char[] @Nullable [] toArray() {
     char[][] result = new char[max + 1][];
     for (Entry<Character, String> entry : map.entrySet()) {
       result[entry.getKey()] = entry.getValue().toCharArray();
diff --git a/android/guava/src/com/google/common/escape/ElementTypesAreNonnullByDefault.java b/android/guava/src/com/google/common/escape/ElementTypesAreNonnullByDefault.java
new file mode 100644
index 000000000000..992c9a3e4d84
--- /dev/null
+++ b/android/guava/src/com/google/common/escape/ElementTypesAreNonnullByDefault.java
@@ -0,0 +1,41 @@
+/*
+ * Copyright (C) 2021 The Guava Authors
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package com.google.common.escape;
+
+import static java.lang.annotation.ElementType.FIELD;
+import static java.lang.annotation.ElementType.METHOD;
+import static java.lang.annotation.ElementType.PARAMETER;
+import static java.lang.annotation.ElementType.TYPE;
+import static java.lang.annotation.RetentionPolicy.RUNTIME;
+
+import com.google.common.annotations.GwtCompatible;
+import java.lang.annotation.Retention;
+import java.lang.annotation.Target;
+import javax.annotation.Nonnull;
+import javax.annotation.meta.TypeQualifierDefault;
+
+/**
+ * Marks all "top-level" types as non-null in a way that is recognized by Kotlin. Note that this
+ * unfortunately includes type-variable usages, so we also provide {@link ParametricNullness} to
+ * "undo" it as best we can.
+ */
+@GwtCompatible
+@Retention(RUNTIME)
+@Target(TYPE)
+@TypeQualifierDefault({FIELD, METHOD, PARAMETER})
+@Nonnull
+@interface ElementTypesAreNonnullByDefault {}
diff --git a/android/guava/src/com/google/common/escape/Escaper.java b/android/guava/src/com/google/common/escape/Escaper.java
index 0d32a09a1e18..31b7df0e64ab 100644
--- a/android/guava/src/com/google/common/escape/Escaper.java
+++ b/android/guava/src/com/google/common/escape/Escaper.java
@@ -56,6 +56,7 @@
  */
 @DoNotMock("Use Escapers.nullEscaper() or another methods from the *Escapers classes")
 @GwtCompatible
+@ElementTypesAreNonnullByDefault
 public abstract class Escaper {
   // TODO(dbeaumont): evaluate custom implementations, considering package private constructor.
   /** Constructor for use by subclasses. */
@@ -84,13 +85,7 @@ protected Escaper() {}
    */
   public abstract String escape(String string);
 
-  private final Function<String, String> asFunction =
-      new Function<String, String>() {
-        @Override
-        public String apply(String from) {
-          return escape(from);
-        }
-      };
+  private final Function<String, String> asFunction = this::escape;
 
   /** Returns a {@link Function} that invokes {@link #escape(String)} on this escaper. */
   public final Function<String, String> asFunction() {
diff --git a/android/guava/src/com/google/common/escape/Escapers.java b/android/guava/src/com/google/common/escape/Escapers.java
index 5de338a98663..acfb82ce29ae 100644
--- a/android/guava/src/com/google/common/escape/Escapers.java
+++ b/android/guava/src/com/google/common/escape/Escapers.java
@@ -16,12 +16,12 @@
 
 import static com.google.common.base.Preconditions.checkNotNull;
 
-import com.google.common.annotations.Beta;
 import com.google.common.annotations.GwtCompatible;
 import com.google.errorprone.annotations.CanIgnoreReturnValue;
 import java.util.HashMap;
 import java.util.Map;
-import org.checkerframework.checker.nullness.compatqual.NullableDecl;
+import javax.annotation.CheckForNull;
+import org.checkerframework.checker.nullness.qual.Nullable;
 
 /**
  * Static utility methods pertaining to {@link Escaper} instances.
@@ -30,8 +30,8 @@
  * @author David Beaumont
  * @since 15.0
  */
-@Beta
 @GwtCompatible
+@ElementTypesAreNonnullByDefault
 public final class Escapers {
   private Escapers() {}
 
@@ -52,6 +52,7 @@ public String escape(String string) {
         }
 
         @Override
+        @CheckForNull
         protected char[] escape(char c) {
           // TODO: Fix tests not to call this directly and make it throw an error.
           return null;
@@ -90,12 +91,11 @@ public static Builder builder() {
    * @author David Beaumont
    * @since 15.0
    */
-  @Beta
   public static final class Builder {
     private final Map<Character, String> replacementMap = new HashMap<>();
     private char safeMin = Character.MIN_VALUE;
     private char safeMax = Character.MAX_VALUE;
-    private String unsafeReplacement = null;
+    @CheckForNull private String unsafeReplacement = null;
 
     // The constructor is exposed via the builder() method above.
     private Builder() {}
@@ -125,7 +125,7 @@ public Builder setSafeRange(char safeMin, char safeMax) {
      * @return the builder instance
      */
     @CanIgnoreReturnValue
-    public Builder setUnsafeReplacement(@NullableDecl String unsafeReplacement) {
+    public Builder setUnsafeReplacement(@Nullable String unsafeReplacement) {
       this.unsafeReplacement = unsafeReplacement;
       return this;
     }
@@ -151,10 +151,12 @@ public Builder addEscape(char c, String replacement) {
     /** Returns a new escaper based on the current state of the builder. */
     public Escaper build() {
       return new ArrayBasedCharEscaper(replacementMap, safeMin, safeMax) {
+        @CheckForNull
         private final char[] replacementChars =
             unsafeReplacement != null ? unsafeReplacement.toCharArray() : null;
 
         @Override
+        @CheckForNull
         protected char[] escapeUnsafe(char c) {
           return replacementChars;
         }
@@ -198,6 +200,7 @@ static UnicodeEscaper asUnicodeEscaper(Escaper escaper) {
    * @param c the character to escape if necessary
    * @return the replacement string, or {@code null} if no escaping was needed
    */
+  @CheckForNull
   public static String computeReplacement(CharEscaper escaper, char c) {
     return stringOrNull(escaper.escape(c));
   }
@@ -211,18 +214,21 @@ public static String computeReplacement(CharEscaper escaper, char c) {
    * @param cp the Unicode code point to escape if necessary
    * @return the replacement string, or {@code null} if no escaping was needed
    */
+  @CheckForNull
   public static String computeReplacement(UnicodeEscaper escaper, int cp) {
     return stringOrNull(escaper.escape(cp));
   }
 
-  private static String stringOrNull(char[] in) {
+  @CheckForNull
+  private static String stringOrNull(@CheckForNull char[] in) {
     return (in == null) ? null : new String(in);
   }
 
   /** Private helper to wrap a CharEscaper as a UnicodeEscaper. */
-  private static UnicodeEscaper wrap(final CharEscaper escaper) {
+  private static UnicodeEscaper wrap(CharEscaper escaper) {
     return new UnicodeEscaper() {
       @Override
+      @CheckForNull
       protected char[] escape(int cp) {
         // If a code point maps to a single character, just escape that.
         if (cp < Character.MIN_SUPPLEMENTARY_CODE_POINT) {
diff --git a/android/guava/src/com/google/common/escape/ParametricNullness.java b/android/guava/src/com/google/common/escape/ParametricNullness.java
new file mode 100644
index 000000000000..d9412065ffd9
--- /dev/null
+++ b/android/guava/src/com/google/common/escape/ParametricNullness.java
@@ -0,0 +1,52 @@
+/*
+ * Copyright (C) 2021 The Guava Authors
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package com.google.common.escape;
+
+import static java.lang.annotation.ElementType.FIELD;
+import static java.lang.annotation.ElementType.METHOD;
+import static java.lang.annotation.ElementType.PARAMETER;
+import static java.lang.annotation.RetentionPolicy.RUNTIME;
+
+import com.google.common.annotations.GwtCompatible;
+import java.lang.annotation.Retention;
+import java.lang.annotation.Target;
+
+/**
+ * Marks a "top-level" type-variable usage as the closest we can get to "non-nullable when
+ * non-nullable; nullable when nullable" (like the Android <a
+ * href="https://android.googlesource.com/platform/libcore/+/master/luni/src/main/java/libcore/util/NullFromTypeParam.java">{@code
+ * NullFromTypeParam}</a>).
+ *
+ * <p>Consumers of this annotation include:
+ *
+ * <ul>
+ *   <li>Kotlin, for which it makes the type-variable usage (a) a Kotlin platform type when the type
+ *       argument is non-nullable and (b) nullable when the type argument is nullable. We use this
+ *       to "undo" {@link ElementTypesAreNonnullByDefault}.
+ *   <li><a href="https://developers.google.com/j2objc">J2ObjC</a>
+ *   <li>{@code NullPointerTester}, at least in the Android backport (where the type-use annotations
+ *       {@code NullPointerTester} would need are not available) and in case of <a
+ *       href="https://bugs.openjdk.java.net/browse/JDK-8202469">JDK-8202469</a>
+ * </ul>
+ *
+ */
+@GwtCompatible
+@Retention(RUNTIME)
+@Target({FIELD, METHOD, PARAMETER})
+@javax.annotation.meta.TypeQualifierNickname
+@javax.annotation.Nonnull(when = javax.annotation.meta.When.UNKNOWN)
+@interface ParametricNullness {}
diff --git a/android/guava/src/com/google/common/escape/Platform.java b/android/guava/src/com/google/common/escape/Platform.java
index 99a7d4f0f237..dc6610c041bb 100644
--- a/android/guava/src/com/google/common/escape/Platform.java
+++ b/android/guava/src/com/google/common/escape/Platform.java
@@ -22,6 +22,7 @@
  * @author Jesse Wilson
  */
 @GwtCompatible(emulated = true)
+@ElementTypesAreNonnullByDefault
 final class Platform {
   private Platform() {}
 
diff --git a/android/guava/src/com/google/common/escape/UnicodeEscaper.java b/android/guava/src/com/google/common/escape/UnicodeEscaper.java
index 06421624ff1b..280915c7551e 100644
--- a/android/guava/src/com/google/common/escape/UnicodeEscaper.java
+++ b/android/guava/src/com/google/common/escape/UnicodeEscaper.java
@@ -16,8 +16,8 @@
 
 import static com.google.common.base.Preconditions.checkNotNull;
 
-import com.google.common.annotations.Beta;
 import com.google.common.annotations.GwtCompatible;
+import javax.annotation.CheckForNull;
 
 /**
  * An {@link Escaper} that converts literal text into a format safe for inclusion in a particular
@@ -49,8 +49,8 @@
  * @author David Beaumont
  * @since 15.0
  */
-@Beta
 @GwtCompatible
+@ElementTypesAreNonnullByDefault
 public abstract class UnicodeEscaper extends Escaper {
   /** The amount of padding (chars) to use when growing the escape buffer. */
   private static final int DEST_PAD = 32;
@@ -77,6 +77,7 @@ protected UnicodeEscaper() {}
    * @param cp the Unicode code point to escape if necessary
    * @return the replacement characters, or {@code null} if no escaping was needed
    */
+  @CheckForNull
   protected abstract char[] escape(int cp);
 
   /**
diff --git a/android/guava/src/com/google/common/eventbus/AllowConcurrentEvents.java b/android/guava/src/com/google/common/eventbus/AllowConcurrentEvents.java
index 4c749b401991..28bc4b23e0c3 100644
--- a/android/guava/src/com/google/common/eventbus/AllowConcurrentEvents.java
+++ b/android/guava/src/com/google/common/eventbus/AllowConcurrentEvents.java
@@ -14,7 +14,6 @@
 
 package com.google.common.eventbus;
 
-import com.google.common.annotations.Beta;
 import java.lang.annotation.ElementType;
 import java.lang.annotation.Retention;
 import java.lang.annotation.RetentionPolicy;
@@ -31,5 +30,5 @@
  */
 @Retention(RetentionPolicy.RUNTIME)
 @Target(ElementType.METHOD)
-@Beta
+@ElementTypesAreNonnullByDefault
 public @interface AllowConcurrentEvents {}
diff --git a/android/guava/src/com/google/common/eventbus/AsyncEventBus.java b/android/guava/src/com/google/common/eventbus/AsyncEventBus.java
index 8650a8d86eea..4f387a712841 100644
--- a/android/guava/src/com/google/common/eventbus/AsyncEventBus.java
+++ b/android/guava/src/com/google/common/eventbus/AsyncEventBus.java
@@ -14,7 +14,6 @@
 
 package com.google.common.eventbus;
 
-import com.google.common.annotations.Beta;
 import java.util.concurrent.Executor;
 
 /**
@@ -24,7 +23,7 @@
  * @author Cliff Biffle
  * @since 10.0
  */
-@Beta
+@ElementTypesAreNonnullByDefault
 public class AsyncEventBus extends EventBus {
 
   /**
diff --git a/android/guava/src/com/google/common/eventbus/DeadEvent.java b/android/guava/src/com/google/common/eventbus/DeadEvent.java
index 6dbfee527dbc..2cdb23f712d7 100644
--- a/android/guava/src/com/google/common/eventbus/DeadEvent.java
+++ b/android/guava/src/com/google/common/eventbus/DeadEvent.java
@@ -16,7 +16,6 @@
 
 import static com.google.common.base.Preconditions.checkNotNull;
 
-import com.google.common.annotations.Beta;
 import com.google.common.base.MoreObjects;
 
 /**
@@ -28,7 +27,7 @@
  * @author Cliff Biffle
  * @since 10.0
  */
-@Beta
+@ElementTypesAreNonnullByDefault
 public class DeadEvent {
 
   private final Object source;
diff --git a/android/guava/src/com/google/common/eventbus/Dispatcher.java b/android/guava/src/com/google/common/eventbus/Dispatcher.java
index 11e2de191c70..ff1ae2a197a4 100644
--- a/android/guava/src/com/google/common/eventbus/Dispatcher.java
+++ b/android/guava/src/com/google/common/eventbus/Dispatcher.java
@@ -31,6 +31,7 @@
  *
  * @author Colin Decker
  */
+@ElementTypesAreNonnullByDefault
 abstract class Dispatcher {
 
   /**
diff --git a/android/guava/src/com/google/common/eventbus/ElementTypesAreNonnullByDefault.java b/android/guava/src/com/google/common/eventbus/ElementTypesAreNonnullByDefault.java
new file mode 100644
index 000000000000..e8542bba63ec
--- /dev/null
+++ b/android/guava/src/com/google/common/eventbus/ElementTypesAreNonnullByDefault.java
@@ -0,0 +1,41 @@
+/*
+ * Copyright (C) 2021 The Guava Authors
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package com.google.common.eventbus;
+
+import static java.lang.annotation.ElementType.FIELD;
+import static java.lang.annotation.ElementType.METHOD;
+import static java.lang.annotation.ElementType.PARAMETER;
+import static java.lang.annotation.ElementType.TYPE;
+import static java.lang.annotation.RetentionPolicy.RUNTIME;
+
+import com.google.common.annotations.GwtCompatible;
+import java.lang.annotation.Retention;
+import java.lang.annotation.Target;
+import javax.annotation.Nonnull;
+import javax.annotation.meta.TypeQualifierDefault;
+
+/**
+ * Marks all "top-level" types as non-null in a way that is recognized by Kotlin. Note that this
+ * unfortunately includes type-variable usages, so we also provide {@link ParametricNullness} to
+ * "undo" it as best we can.
+ */
+@GwtCompatible
+@Retention(RUNTIME)
+@Target(TYPE)
+@TypeQualifierDefault({FIELD, METHOD, PARAMETER})
+@Nonnull
+@interface ElementTypesAreNonnullByDefault {}
diff --git a/android/guava/src/com/google/common/eventbus/EventBus.java b/android/guava/src/com/google/common/eventbus/EventBus.java
index e5053990b757..4afc19775627 100644
--- a/android/guava/src/com/google/common/eventbus/EventBus.java
+++ b/android/guava/src/com/google/common/eventbus/EventBus.java
@@ -16,7 +16,6 @@
 
 import static com.google.common.base.Preconditions.checkNotNull;
 
-import com.google.common.annotations.Beta;
 import com.google.common.base.MoreObjects;
 import com.google.common.util.concurrent.MoreExecutors;
 import java.lang.reflect.Method;
@@ -29,6 +28,62 @@
 /**
  * Dispatches events to listeners, and provides ways for listeners to register themselves.
  *
+ * <h2>Avoid EventBus</h2>
+ *
+ * <p><b>We recommend against using EventBus.</b> It was designed many years ago, and newer
+ * libraries offer better ways to decouple components and react to events.
+ *
+ * <p>To decouple components, we recommend a dependency-injection framework. For Android code, most
+ * apps use <a href="https://dagger.dev">Dagger</a>. For server code, common options include <a
+ * href="https://github.com/google/guice/wiki/Motivation">Guice</a> and <a
+ * href="https://docs.spring.io/spring-framework/docs/current/reference/html/core.html#beans-introduction">Spring</a>.
+ * Frameworks typically offer a way to register multiple listeners independently and then request
+ * them together as a set (<a href="https://dagger.dev/dev-guide/multibindings">Dagger</a>, <a
+ * href="https://github.com/google/guice/wiki/Multibindings">Guice</a>, <a
+ * href="https://docs.spring.io/spring-framework/docs/current/reference/html/core.html#beans-autowired-annotation">Spring</a>).
+ *
+ * <p>To react to events, we recommend a reactive-streams framework like <a
+ * href="https://github.com/ReactiveX/RxJava/wiki">RxJava</a> (supplemented with its <a
+ * href="https://github.com/ReactiveX/RxAndroid">RxAndroid</a> extension if you are building for
+ * Android) or <a href="https://projectreactor.io/">Project Reactor</a>. (For the basics of
+ * translating code from using an event bus to using a reactive-streams framework, see these two
+ * guides: <a href="https://blog.jkl.gg/implementing-an-event-bus-with-rxjava-rxbus/">1</a>, <a
+ * href="https://lorentzos.com/rxjava-as-event-bus-the-right-way-10a36bdd49ba">2</a>.) Some usages
+ * of EventBus may be better written using <a
+ * href="https://kotlinlang.org/docs/coroutines-guide.html">Kotlin coroutines</a>, including <a
+ * href="https://kotlinlang.org/docs/flow.html">Flow</a> and <a
+ * href="https://kotlinlang.org/docs/channels.html">Channels</a>. Yet other usages are better served
+ * by individual libraries that provide specialized support for particular use cases.
+ *
+ * <p>Disadvantages of EventBus include:
+ *
+ * <ul>
+ *   <li>It makes the cross-references between producer and subscriber harder to find. This can
+ *       complicate debugging, lead to unintentional reentrant calls, and force apps to eagerly
+ *       initialize all possible subscribers at startup time.
+ *   <li>It uses reflection in ways that break when code is processed by optimizers/minimizers like
+ *       <a href="https://developer.android.com/studio/build/shrink-code">R8 and Proguard</a>.
+ *   <li>It doesn't offer a way to wait for multiple events before taking action. For example, it
+ *       doesn't offer a way to wait for multiple producers to all report that they're "ready," nor
+ *       does it offer a way to batch multiple events from a single producer together.
+ *   <li>It doesn't support backpressure and other features needed for resilience.
+ *   <li>It doesn't provide much control of threading.
+ *   <li>It doesn't offer much monitoring.
+ *   <li>It doesn't propagate exceptions, so apps don't have a way to react to them.
+ *   <li>It doesn't interoperate well with RxJava, coroutines, and other more commonly used
+ *       alternatives.
+ *   <li>It imposes requirements on the lifecycle of its subscribers. For example, if an event
+ *       occurs between when one subscriber is removed and the next subscriber is added, the event
+ *       is dropped.
+ *   <li>Its performance is suboptimal, especially under Android.
+ *   <li>It <a href="https://github.com/google/guava/issues/1431">doesn't support parameterized
+ *       types</a>.
+ *   <li>With the introduction of lambdas in Java 8, EventBus went from less verbose than listeners
+ *       to <a href="https://github.com/google/guava/issues/3311">more verbose</a>.
+ * </ul>
+ *
+ * <h2>EventBus Summary</h2>
+ *
  * <p>The EventBus allows publish-subscribe-style communication between components without requiring
  * the components to explicitly register with one another (and thus be aware of each other). It is
  * designed exclusively to replace traditional Java in-process event distribution using explicit
@@ -92,7 +147,7 @@
  * @author Cliff Biffle
  * @since 10.0
  */
-@Beta
+@ElementTypesAreNonnullByDefault
 public class EventBus {
 
   private static final Logger logger = Logger.getLogger(EventBus.class.getName());
diff --git a/android/guava/src/com/google/common/eventbus/ParametricNullness.java b/android/guava/src/com/google/common/eventbus/ParametricNullness.java
new file mode 100644
index 000000000000..ac91392f75eb
--- /dev/null
+++ b/android/guava/src/com/google/common/eventbus/ParametricNullness.java
@@ -0,0 +1,52 @@
+/*
+ * Copyright (C) 2021 The Guava Authors
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package com.google.common.eventbus;
+
+import static java.lang.annotation.ElementType.FIELD;
+import static java.lang.annotation.ElementType.METHOD;
+import static java.lang.annotation.ElementType.PARAMETER;
+import static java.lang.annotation.RetentionPolicy.RUNTIME;
+
+import com.google.common.annotations.GwtCompatible;
+import java.lang.annotation.Retention;
+import java.lang.annotation.Target;
+
+/**
+ * Marks a "top-level" type-variable usage as the closest we can get to "non-nullable when
+ * non-nullable; nullable when nullable" (like the Android <a
+ * href="https://android.googlesource.com/platform/libcore/+/master/luni/src/main/java/libcore/util/NullFromTypeParam.java">{@code
+ * NullFromTypeParam}</a>).
+ *
+ * <p>Consumers of this annotation include:
+ *
+ * <ul>
+ *   <li>Kotlin, for which it makes the type-variable usage (a) a Kotlin platform type when the type
+ *       argument is non-nullable and (b) nullable when the type argument is nullable. We use this
+ *       to "undo" {@link ElementTypesAreNonnullByDefault}.
+ *   <li><a href="https://developers.google.com/j2objc">J2ObjC</a>
+ *   <li>{@code NullPointerTester}, at least in the Android backport (where the type-use annotations
+ *       {@code NullPointerTester} would need are not available) and in case of <a
+ *       href="https://bugs.openjdk.java.net/browse/JDK-8202469">JDK-8202469</a>
+ * </ul>
+ *
+ */
+@GwtCompatible
+@Retention(RUNTIME)
+@Target({FIELD, METHOD, PARAMETER})
+@javax.annotation.meta.TypeQualifierNickname
+@javax.annotation.Nonnull(when = javax.annotation.meta.When.UNKNOWN)
+@interface ParametricNullness {}
diff --git a/android/guava/src/com/google/common/eventbus/Subscribe.java b/android/guava/src/com/google/common/eventbus/Subscribe.java
index 52b999d98f87..88477f1bae75 100644
--- a/android/guava/src/com/google/common/eventbus/Subscribe.java
+++ b/android/guava/src/com/google/common/eventbus/Subscribe.java
@@ -14,7 +14,6 @@
 
 package com.google.common.eventbus;
 
-import com.google.common.annotations.Beta;
 import java.lang.annotation.ElementType;
 import java.lang.annotation.Retention;
 import java.lang.annotation.RetentionPolicy;
@@ -36,5 +35,5 @@
  */
 @Retention(RetentionPolicy.RUNTIME)
 @Target(ElementType.METHOD)
-@Beta
+@ElementTypesAreNonnullByDefault
 public @interface Subscribe {}
diff --git a/android/guava/src/com/google/common/eventbus/Subscriber.java b/android/guava/src/com/google/common/eventbus/Subscriber.java
index 42a63f2aa986..71ee197c9b25 100644
--- a/android/guava/src/com/google/common/eventbus/Subscriber.java
+++ b/android/guava/src/com/google/common/eventbus/Subscriber.java
@@ -21,7 +21,7 @@
 import java.lang.reflect.InvocationTargetException;
 import java.lang.reflect.Method;
 import java.util.concurrent.Executor;
-import org.checkerframework.checker.nullness.compatqual.NullableDecl;
+import javax.annotation.CheckForNull;
 
 /**
  * A subscriber method on a specific object, plus the executor that should be used for dispatching
@@ -32,6 +32,7 @@
  *
  * @author Colin Decker
  */
+@ElementTypesAreNonnullByDefault
 class Subscriber {
 
   /** Creates a {@code Subscriber} for {@code method} on {@code listener}. */
@@ -63,16 +64,13 @@ private Subscriber(EventBus bus, Object target, Method method) {
   }
 
   /** Dispatches {@code event} to this subscriber using the proper executor. */
-  final void dispatchEvent(final Object event) {
+  final void dispatchEvent(Object event) {
     executor.execute(
-        new Runnable() {
-          @Override
-          public void run() {
-            try {
-              invokeSubscriberMethod(event);
-            } catch (InvocationTargetException e) {
-              bus.handleSubscriberException(e.getCause(), context(event));
-            }
+        () -> {
+          try {
+            invokeSubscriberMethod(event);
+          } catch (InvocationTargetException e) {
+            bus.handleSubscriberException(e.getCause(), context(event));
           }
         });
   }
@@ -108,7 +106,7 @@ public final int hashCode() {
   }
 
   @Override
-  public final boolean equals(@NullableDecl Object obj) {
+  public final boolean equals(@CheckForNull Object obj) {
     if (obj instanceof Subscriber) {
       Subscriber that = (Subscriber) obj;
       // Use == so that different equal instances will still receive events.
diff --git a/android/guava/src/com/google/common/eventbus/SubscriberExceptionContext.java b/android/guava/src/com/google/common/eventbus/SubscriberExceptionContext.java
index 6ddd86f21198..63c7d557fec9 100644
--- a/android/guava/src/com/google/common/eventbus/SubscriberExceptionContext.java
+++ b/android/guava/src/com/google/common/eventbus/SubscriberExceptionContext.java
@@ -23,6 +23,7 @@
  *
  * @since 16.0
  */
+@ElementTypesAreNonnullByDefault
 public class SubscriberExceptionContext {
   private final EventBus eventBus;
   private final Object event;
@@ -31,7 +32,7 @@ public class SubscriberExceptionContext {
 
   /**
    * @param eventBus The {@link EventBus} that handled the event and the subscriber. Useful for
-   *     broadcasting a a new event based on the error.
+   *     broadcasting a new event based on the error.
    * @param event The event object that caused the subscriber to throw.
    * @param subscriber The source subscriber context.
    * @param subscriberMethod the subscribed method.
@@ -46,7 +47,7 @@ public class SubscriberExceptionContext {
 
   /**
    * @return The {@link EventBus} that handled the event and the subscriber. Useful for broadcasting
-   *     a a new event based on the error.
+   *     a new event based on the error.
    */
   public EventBus getEventBus() {
     return eventBus;
diff --git a/android/guava/src/com/google/common/eventbus/SubscriberExceptionHandler.java b/android/guava/src/com/google/common/eventbus/SubscriberExceptionHandler.java
index c239ad74fc87..1c2fbb109adb 100644
--- a/android/guava/src/com/google/common/eventbus/SubscriberExceptionHandler.java
+++ b/android/guava/src/com/google/common/eventbus/SubscriberExceptionHandler.java
@@ -14,11 +14,13 @@
 
 package com.google.common.eventbus;
 
+
 /**
  * Handler for exceptions thrown by event subscribers.
  *
  * @since 16.0
  */
+@ElementTypesAreNonnullByDefault
 public interface SubscriberExceptionHandler {
   /** Handles exceptions thrown by subscribers. */
   void handleException(Throwable exception, SubscriberExceptionContext context);
diff --git a/android/guava/src/com/google/common/eventbus/SubscriberRegistry.java b/android/guava/src/com/google/common/eventbus/SubscriberRegistry.java
index 6a6ceac1872e..46e982016c55 100644
--- a/android/guava/src/com/google/common/eventbus/SubscriberRegistry.java
+++ b/android/guava/src/com/google/common/eventbus/SubscriberRegistry.java
@@ -46,13 +46,14 @@
 import java.util.Set;
 import java.util.concurrent.ConcurrentMap;
 import java.util.concurrent.CopyOnWriteArraySet;
-import org.checkerframework.checker.nullness.compatqual.NullableDecl;
+import javax.annotation.CheckForNull;
 
 /**
  * Registry of subscribers to a single event bus.
  *
  * @author Colin Decker
  */
+@ElementTypesAreNonnullByDefault
 final class SubscriberRegistry {
 
   /**
@@ -258,7 +259,7 @@ public int hashCode() {
     }
 
     @Override
-    public boolean equals(@NullableDecl Object o) {
+    public boolean equals(@CheckForNull Object o) {
       if (o instanceof MethodIdentifier) {
         MethodIdentifier ident = (MethodIdentifier) o;
         return name.equals(ident.name) && parameterTypes.equals(ident.parameterTypes);
diff --git a/android/guava/src/com/google/common/graph/AbstractBaseGraph.java b/android/guava/src/com/google/common/graph/AbstractBaseGraph.java
index b68656b3d6e9..797468b7aa92 100644
--- a/android/guava/src/com/google/common/graph/AbstractBaseGraph.java
+++ b/android/guava/src/com/google/common/graph/AbstractBaseGraph.java
@@ -21,7 +21,6 @@
 import static com.google.common.base.Preconditions.checkState;
 import static com.google.common.graph.GraphConstants.ENDPOINTS_MISMATCH;
 
-import com.google.common.base.Function;
 import com.google.common.collect.ImmutableSet;
 import com.google.common.collect.Iterators;
 import com.google.common.collect.Sets;
@@ -30,7 +29,7 @@
 import com.google.common.primitives.Ints;
 import java.util.AbstractSet;
 import java.util.Set;
-import org.checkerframework.checker.nullness.compatqual.NullableDecl;
+import javax.annotation.CheckForNull;
 
 /**
  * This class provides a skeletal implementation of {@link BaseGraph}.
@@ -41,6 +40,7 @@
  * @author James Sexton
  * @param <N> Node parameter type
  */
+@ElementTypesAreNonnullByDefault
 abstract class AbstractBaseGraph<N> implements BaseGraph<N> {
 
   /**
@@ -76,7 +76,7 @@ public int size() {
       }
 
       @Override
-      public boolean remove(Object o) {
+      public boolean remove(@CheckForNull Object o) {
         throw new UnsupportedOperationException();
       }
 
@@ -85,7 +85,7 @@ public boolean remove(Object o) {
       // Graph<LinkedList>.
       @SuppressWarnings("unchecked")
       @Override
-      public boolean contains(@NullableDecl Object obj) {
+      public boolean contains(@CheckForNull Object obj) {
         if (!(obj instanceof EndpointPair)) {
           return false;
         }
@@ -114,31 +114,16 @@ public UnmodifiableIterator<EndpointPair<N>> iterator() {
               Iterators.concat(
                   Iterators.transform(
                       graph.predecessors(node).iterator(),
-                      new Function<N, EndpointPair<N>>() {
-                        @Override
-                        public EndpointPair<N> apply(N predecessor) {
-                          return EndpointPair.ordered(predecessor, node);
-                        }
-                      }),
+                      (N predecessor) -> EndpointPair.ordered(predecessor, node)),
                   Iterators.transform(
                       // filter out 'node' from successors (already covered by predecessors, above)
                       Sets.difference(graph.successors(node), ImmutableSet.of(node)).iterator(),
-                      new Function<N, EndpointPair<N>>() {
-                        @Override
-                        public EndpointPair<N> apply(N successor) {
-                          return EndpointPair.ordered(node, successor);
-                        }
-                      })));
+                      (N successor) -> EndpointPair.ordered(node, successor))));
         } else {
           return Iterators.unmodifiableIterator(
               Iterators.transform(
                   graph.adjacentNodes(node).iterator(),
-                  new Function<N, EndpointPair<N>>() {
-                    @Override
-                    public EndpointPair<N> apply(N adjacentNode) {
-                      return EndpointPair.unordered(node, adjacentNode);
-                    }
-                  }));
+                  (N adjacentNode) -> EndpointPair.unordered(node, adjacentNode)));
         }
       }
     };
diff --git a/android/guava/src/com/google/common/graph/AbstractDirectedNetworkConnections.java b/android/guava/src/com/google/common/graph/AbstractDirectedNetworkConnections.java
index 8335d0c5f345..ac452d4d610a 100644
--- a/android/guava/src/com/google/common/graph/AbstractDirectedNetworkConnections.java
+++ b/android/guava/src/com/google/common/graph/AbstractDirectedNetworkConnections.java
@@ -20,6 +20,7 @@
 import static com.google.common.base.Preconditions.checkState;
 import static com.google.common.graph.Graphs.checkNonNegative;
 import static com.google.common.graph.Graphs.checkPositive;
+import static java.util.Objects.requireNonNull;
 
 import com.google.common.collect.Iterables;
 import com.google.common.collect.Iterators;
@@ -30,7 +31,7 @@
 import java.util.Collections;
 import java.util.Map;
 import java.util.Set;
-import org.checkerframework.checker.nullness.compatqual.NullableDecl;
+import javax.annotation.CheckForNull;
 
 /**
  * A base implementation of {@link NetworkConnections} for directed networks.
@@ -39,17 +40,17 @@
  * @param <N> Node parameter type
  * @param <E> Edge parameter type
  */
+@ElementTypesAreNonnullByDefault
 abstract class AbstractDirectedNetworkConnections<N, E> implements NetworkConnections<N, E> {
   /** Keys are edges incoming to the origin node, values are the source node. */
-  protected final Map<E, N> inEdgeMap;
+  final Map<E, N> inEdgeMap;
 
   /** Keys are edges outgoing from the origin node, values are the target node. */
-  protected final Map<E, N> outEdgeMap;
+  final Map<E, N> outEdgeMap;
 
   private int selfLoopCount;
 
-  protected AbstractDirectedNetworkConnections(
-      Map<E, N> inEdgeMap, Map<E, N> outEdgeMap, int selfLoopCount) {
+  AbstractDirectedNetworkConnections(Map<E, N> inEdgeMap, Map<E, N> outEdgeMap, int selfLoopCount) {
     this.inEdgeMap = checkNotNull(inEdgeMap);
     this.outEdgeMap = checkNotNull(outEdgeMap);
     this.selfLoopCount = checkNonNegative(selfLoopCount);
@@ -79,7 +80,7 @@ public int size() {
       }
 
       @Override
-      public boolean contains(@NullableDecl Object obj) {
+      public boolean contains(@CheckForNull Object obj) {
         return inEdgeMap.containsKey(obj) || outEdgeMap.containsKey(obj);
       }
     };
@@ -99,7 +100,8 @@ public Set<E> outEdges() {
   public N adjacentNode(E edge) {
     // Since the reference node is defined to be 'source' for directed graphs,
     // we can assume this edge lives in the set of outgoing edges.
-    return checkNotNull(outEdgeMap.get(edge));
+    // (We're relying on callers to call this method only with an edge that's in the graph.)
+    return requireNonNull(outEdgeMap.get(edge));
   }
 
   @Override
@@ -108,13 +110,15 @@ public N removeInEdge(E edge, boolean isSelfLoop) {
       checkNonNegative(--selfLoopCount);
     }
     N previousNode = inEdgeMap.remove(edge);
-    return checkNotNull(previousNode);
+    // We're relying on callers to call this method only with an edge that's in the graph.
+    return requireNonNull(previousNode);
   }
 
   @Override
   public N removeOutEdge(E edge) {
     N previousNode = outEdgeMap.remove(edge);
-    return checkNotNull(previousNode);
+    // We're relying on callers to call this method only with an edge that's in the graph.
+    return requireNonNull(previousNode);
   }
 
   @Override
diff --git a/android/guava/src/com/google/common/graph/AbstractGraph.java b/android/guava/src/com/google/common/graph/AbstractGraph.java
index fc71345ff6a6..9402be5d9360 100644
--- a/android/guava/src/com/google/common/graph/AbstractGraph.java
+++ b/android/guava/src/com/google/common/graph/AbstractGraph.java
@@ -17,7 +17,7 @@
 package com.google.common.graph;
 
 import com.google.common.annotations.Beta;
-import org.checkerframework.checker.nullness.compatqual.NullableDecl;
+import javax.annotation.CheckForNull;
 
 /**
  * This class provides a skeletal implementation of {@link Graph}. It is recommended to extend this
@@ -28,10 +28,11 @@
  * @since 20.0
  */
 @Beta
+@ElementTypesAreNonnullByDefault
 public abstract class AbstractGraph<N> extends AbstractBaseGraph<N> implements Graph<N> {
 
   @Override
-  public final boolean equals(@NullableDecl Object obj) {
+  public final boolean equals(@CheckForNull Object obj) {
     if (obj == this) {
       return true;
     }
diff --git a/android/guava/src/com/google/common/graph/AbstractGraphBuilder.java b/android/guava/src/com/google/common/graph/AbstractGraphBuilder.java
index 84e461a46c37..a4e1543f1d63 100644
--- a/android/guava/src/com/google/common/graph/AbstractGraphBuilder.java
+++ b/android/guava/src/com/google/common/graph/AbstractGraphBuilder.java
@@ -23,6 +23,7 @@
  *
  * @author James Sexton
  */
+@ElementTypesAreNonnullByDefault
 abstract class AbstractGraphBuilder<N> {
   final boolean directed;
   boolean allowsSelfLoops = false;
diff --git a/android/guava/src/com/google/common/graph/AbstractNetwork.java b/android/guava/src/com/google/common/graph/AbstractNetwork.java
index fad15145f3b5..9afbb0377b81 100644
--- a/android/guava/src/com/google/common/graph/AbstractNetwork.java
+++ b/android/guava/src/com/google/common/graph/AbstractNetwork.java
@@ -34,7 +34,7 @@
 import java.util.Iterator;
 import java.util.Map;
 import java.util.Set;
-import org.checkerframework.checker.nullness.compatqual.NullableDecl;
+import javax.annotation.CheckForNull;
 
 /**
  * This class provides a skeletal implementation of {@link Network}. It is recommended to extend
@@ -49,6 +49,7 @@
  * @since 20.0
  */
 @Beta
+@ElementTypesAreNonnullByDefault
 public abstract class AbstractNetwork<N, E> implements Network<N, E> {
 
   @Override
@@ -89,7 +90,7 @@ public int size() {
           // Network<LinkedList>.
           @SuppressWarnings("unchecked")
           @Override
-          public boolean contains(@NullableDecl Object obj) {
+          public boolean contains(@CheckForNull Object obj) {
             if (!(obj instanceof EndpointPair)) {
               return false;
             }
@@ -194,7 +195,7 @@ public boolean apply(E edge) {
   }
 
   @Override
-  @NullableDecl
+  @CheckForNull
   public E edgeConnectingOrNull(N nodeU, N nodeV) {
     Set<E> edgesConnecting = edgesConnecting(nodeU, nodeV);
     switch (edgesConnecting.size()) {
@@ -208,7 +209,7 @@ public E edgeConnectingOrNull(N nodeU, N nodeV) {
   }
 
   @Override
-  @NullableDecl
+  @CheckForNull
   public E edgeConnectingOrNull(EndpointPair<N> endpoints) {
     validateEndpoints(endpoints);
     return edgeConnectingOrNull(endpoints.nodeU(), endpoints.nodeV());
@@ -244,7 +245,7 @@ protected final boolean isOrderingCompatible(EndpointPair<?> endpoints) {
   }
 
   @Override
-  public final boolean equals(@NullableDecl Object obj) {
+  public final boolean equals(@CheckForNull Object obj) {
     if (obj == this) {
       return true;
     }
diff --git a/android/guava/src/com/google/common/graph/AbstractUndirectedNetworkConnections.java b/android/guava/src/com/google/common/graph/AbstractUndirectedNetworkConnections.java
index 03279d068ec0..8f736d7baa23 100644
--- a/android/guava/src/com/google/common/graph/AbstractUndirectedNetworkConnections.java
+++ b/android/guava/src/com/google/common/graph/AbstractUndirectedNetworkConnections.java
@@ -18,10 +18,12 @@
 
 import static com.google.common.base.Preconditions.checkNotNull;
 import static com.google.common.base.Preconditions.checkState;
+import static java.util.Objects.requireNonNull;
 
 import java.util.Collections;
 import java.util.Map;
 import java.util.Set;
+import javax.annotation.CheckForNull;
 
 /**
  * A base implementation of {@link NetworkConnections} for undirected networks.
@@ -30,11 +32,12 @@
  * @param <N> Node parameter type
  * @param <E> Edge parameter type
  */
+@ElementTypesAreNonnullByDefault
 abstract class AbstractUndirectedNetworkConnections<N, E> implements NetworkConnections<N, E> {
   /** Keys are edges incident to the origin node, values are the node at the other end. */
-  protected final Map<E, N> incidentEdgeMap;
+  final Map<E, N> incidentEdgeMap;
 
-  protected AbstractUndirectedNetworkConnections(Map<E, N> incidentEdgeMap) {
+  AbstractUndirectedNetworkConnections(Map<E, N> incidentEdgeMap) {
     this.incidentEdgeMap = checkNotNull(incidentEdgeMap);
   }
 
@@ -65,10 +68,12 @@ public Set<E> outEdges() {
 
   @Override
   public N adjacentNode(E edge) {
-    return checkNotNull(incidentEdgeMap.get(edge));
+    // We're relying on callers to call this method only with an edge that's in the graph.
+    return requireNonNull(incidentEdgeMap.get(edge));
   }
 
   @Override
+  @CheckForNull
   public N removeInEdge(E edge, boolean isSelfLoop) {
     if (!isSelfLoop) {
       return removeOutEdge(edge);
@@ -79,7 +84,8 @@ public N removeInEdge(E edge, boolean isSelfLoop) {
   @Override
   public N removeOutEdge(E edge) {
     N previousNode = incidentEdgeMap.remove(edge);
-    return checkNotNull(previousNode);
+    // We're relying on callers to call this method only with an edge that's in the graph.
+    return requireNonNull(previousNode);
   }
 
   @Override
diff --git a/android/guava/src/com/google/common/graph/AbstractValueGraph.java b/android/guava/src/com/google/common/graph/AbstractValueGraph.java
index be2b7cce4bc0..940aeffc525d 100644
--- a/android/guava/src/com/google/common/graph/AbstractValueGraph.java
+++ b/android/guava/src/com/google/common/graph/AbstractValueGraph.java
@@ -16,12 +16,14 @@
 
 package com.google.common.graph;
 
+import static java.util.Objects.requireNonNull;
+
 import com.google.common.annotations.Beta;
 import com.google.common.base.Function;
 import com.google.common.collect.Maps;
 import java.util.Map;
 import java.util.Set;
-import org.checkerframework.checker.nullness.compatqual.NullableDecl;
+import javax.annotation.CheckForNull;
 
 /**
  * This class provides a skeletal implementation of {@link ValueGraph}. It is recommended to extend
@@ -36,6 +38,7 @@
  * @since 20.0
  */
 @Beta
+@ElementTypesAreNonnullByDefault
 public abstract class AbstractValueGraph<N, V> extends AbstractBaseGraph<N>
     implements ValueGraph<N, V> {
 
@@ -105,7 +108,7 @@ public int outDegree(N node) {
   }
 
   @Override
-  public final boolean equals(@NullableDecl Object obj) {
+  public final boolean equals(@CheckForNull Object obj) {
     if (obj == this) {
       return true;
     }
@@ -142,7 +145,8 @@ private static <N, V> Map<EndpointPair<N>, V> edgeValueMap(final ValueGraph<N, V
         new Function<EndpointPair<N>, V>() {
           @Override
           public V apply(EndpointPair<N> edge) {
-            return graph.edgeValueOrDefault(edge.nodeU(), edge.nodeV(), null);
+            // requireNonNull is safe because the endpoint pair comes from the graph.
+            return requireNonNull(graph.edgeValueOrDefault(edge.nodeU(), edge.nodeV(), null));
           }
         };
     return Maps.asMap(graph.edges(), edgeToValueFn);
diff --git a/android/guava/src/com/google/common/graph/BaseGraph.java b/android/guava/src/com/google/common/graph/BaseGraph.java
index 1df5de7f174e..68813e18a76d 100644
--- a/android/guava/src/com/google/common/graph/BaseGraph.java
+++ b/android/guava/src/com/google/common/graph/BaseGraph.java
@@ -24,6 +24,7 @@
  * @author James Sexton
  * @param <N> Node parameter type
  */
+@ElementTypesAreNonnullByDefault
 interface BaseGraph<N> extends SuccessorsFunction<N>, PredecessorsFunction<N> {
   //
   // Graph-level accessors
diff --git a/android/guava/src/com/google/common/graph/DirectedGraphConnections.java b/android/guava/src/com/google/common/graph/DirectedGraphConnections.java
index 12887b739ecf..0feb973f3f79 100644
--- a/android/guava/src/com/google/common/graph/DirectedGraphConnections.java
+++ b/android/guava/src/com/google/common/graph/DirectedGraphConnections.java
@@ -40,7 +40,7 @@
 import java.util.Map.Entry;
 import java.util.Set;
 import java.util.concurrent.atomic.AtomicBoolean;
-import org.checkerframework.checker.nullness.compatqual.NullableDecl;
+import javax.annotation.CheckForNull;
 
 /**
  * An implementation of {@link GraphConnections} for directed graphs.
@@ -50,6 +50,7 @@
  * @param <N> Node parameter type
  * @param <V> Value parameter type
  */
+@ElementTypesAreNonnullByDefault
 final class DirectedGraphConnections<N, V> implements GraphConnections<N, V> {
   /**
    * A wrapper class to indicate a node is both a predecessor and successor while still providing
@@ -82,7 +83,7 @@ static final class Pred<N> extends NodeConnection<N> {
       }
 
       @Override
-      public boolean equals(Object that) {
+      public boolean equals(@CheckForNull Object that) {
         if (that instanceof Pred) {
           return this.node.equals(((Pred<?>) that).node);
         } else {
@@ -103,7 +104,7 @@ static final class Succ<N> extends NodeConnection<N> {
       }
 
       @Override
-      public boolean equals(Object that) {
+      public boolean equals(@CheckForNull Object that) {
         if (that instanceof Succ) {
           return this.node.equals(((Succ<?>) that).node);
         } else {
@@ -133,14 +134,14 @@ public int hashCode() {
    * LinkedHashMap combines two such edges into a single node-value pair, even though the edges may
    * not have been inserted consecutively.
    */
-  @NullableDecl private final List<NodeConnection<N>> orderedNodeConnections;
+  @CheckForNull private final List<NodeConnection<N>> orderedNodeConnections;
 
   private int predecessorCount;
   private int successorCount;
 
   private DirectedGraphConnections(
       Map<N, Object> adjacentNodeValues,
-      @NullableDecl List<NodeConnection<N>> orderedNodeConnections,
+      @CheckForNull List<NodeConnection<N>> orderedNodeConnections,
       int predecessorCount,
       int successorCount) {
     this.adjacentNodeValues = checkNotNull(adjacentNodeValues);
@@ -162,13 +163,13 @@ static <N, V> DirectedGraphConnections<N, V> of(ElementOrder<N> incidentEdgeOrde
         orderedNodeConnections = null;
         break;
       case STABLE:
-        orderedNodeConnections = new ArrayList<NodeConnection<N>>();
+        orderedNodeConnections = new ArrayList<>();
         break;
       default:
         throw new AssertionError(incidentEdgeOrder.type());
     }
 
-    return new DirectedGraphConnections<N, V>(
+    return new DirectedGraphConnections<>(
         /* adjacentNodeValues = */ new HashMap<N, Object>(initialCapacity, INNER_LOAD_FACTOR),
         orderedNodeConnections,
         /* predecessorCount = */ 0,
@@ -238,10 +239,11 @@ public Set<N> adjacentNodes() {
       return new AbstractSet<N>() {
         @Override
         public UnmodifiableIterator<N> iterator() {
-          final Iterator<NodeConnection<N>> nodeConnections = orderedNodeConnections.iterator();
-          final Set<N> seenNodes = new HashSet<>();
+          Iterator<NodeConnection<N>> nodeConnections = orderedNodeConnections.iterator();
+          Set<N> seenNodes = new HashSet<>();
           return new AbstractIterator<N>() {
             @Override
+            @CheckForNull
             protected N computeNext() {
               while (nodeConnections.hasNext()) {
                 NodeConnection<N> nodeConnection = nodeConnections.next();
@@ -261,7 +263,7 @@ public int size() {
         }
 
         @Override
-        public boolean contains(@NullableDecl Object obj) {
+        public boolean contains(@CheckForNull Object obj) {
           return adjacentNodeValues.containsKey(obj);
         }
       };
@@ -274,9 +276,10 @@ public Set<N> predecessors() {
       @Override
       public UnmodifiableIterator<N> iterator() {
         if (orderedNodeConnections == null) {
-          final Iterator<Entry<N, Object>> entries = adjacentNodeValues.entrySet().iterator();
+          Iterator<Entry<N, Object>> entries = adjacentNodeValues.entrySet().iterator();
           return new AbstractIterator<N>() {
             @Override
+            @CheckForNull
             protected N computeNext() {
               while (entries.hasNext()) {
                 Entry<N, Object> entry = entries.next();
@@ -288,9 +291,10 @@ protected N computeNext() {
             }
           };
         } else {
-          final Iterator<NodeConnection<N>> nodeConnections = orderedNodeConnections.iterator();
+          Iterator<NodeConnection<N>> nodeConnections = orderedNodeConnections.iterator();
           return new AbstractIterator<N>() {
             @Override
+            @CheckForNull
             protected N computeNext() {
               while (nodeConnections.hasNext()) {
                 NodeConnection<N> nodeConnection = nodeConnections.next();
@@ -310,7 +314,7 @@ public int size() {
       }
 
       @Override
-      public boolean contains(@NullableDecl Object obj) {
+      public boolean contains(@CheckForNull Object obj) {
         return isPredecessor(adjacentNodeValues.get(obj));
       }
     };
@@ -322,9 +326,10 @@ public Set<N> successors() {
       @Override
       public UnmodifiableIterator<N> iterator() {
         if (orderedNodeConnections == null) {
-          final Iterator<Entry<N, Object>> entries = adjacentNodeValues.entrySet().iterator();
+          Iterator<Entry<N, Object>> entries = adjacentNodeValues.entrySet().iterator();
           return new AbstractIterator<N>() {
             @Override
+            @CheckForNull
             protected N computeNext() {
               while (entries.hasNext()) {
                 Entry<N, Object> entry = entries.next();
@@ -336,9 +341,10 @@ protected N computeNext() {
             }
           };
         } else {
-          final Iterator<NodeConnection<N>> nodeConnections = orderedNodeConnections.iterator();
+          Iterator<NodeConnection<N>> nodeConnections = orderedNodeConnections.iterator();
           return new AbstractIterator<N>() {
             @Override
+            @CheckForNull
             protected N computeNext() {
               while (nodeConnections.hasNext()) {
                 NodeConnection<N> nodeConnection = nodeConnections.next();
@@ -358,55 +364,43 @@ public int size() {
       }
 
       @Override
-      public boolean contains(@NullableDecl Object obj) {
+      public boolean contains(@CheckForNull Object obj) {
         return isSuccessor(adjacentNodeValues.get(obj));
       }
     };
   }
 
   @Override
-  public Iterator<EndpointPair<N>> incidentEdgeIterator(final N thisNode) {
+  public Iterator<EndpointPair<N>> incidentEdgeIterator(N thisNode) {
     checkNotNull(thisNode);
 
-    final Iterator<EndpointPair<N>> resultWithDoubleSelfLoop;
+    Iterator<EndpointPair<N>> resultWithDoubleSelfLoop;
     if (orderedNodeConnections == null) {
       resultWithDoubleSelfLoop =
           Iterators.concat(
               Iterators.transform(
                   predecessors().iterator(),
-                  new Function<N, EndpointPair<N>>() {
-                    @Override
-                    public EndpointPair<N> apply(N predecessor) {
-                      return EndpointPair.ordered(predecessor, thisNode);
-                    }
-                  }),
+                  (N predecessor) -> EndpointPair.ordered(predecessor, thisNode)),
               Iterators.transform(
                   successors().iterator(),
-                  new Function<N, EndpointPair<N>>() {
-                    @Override
-                    public EndpointPair<N> apply(N successor) {
-                      return EndpointPair.ordered(thisNode, successor);
-                    }
-                  }));
+                  (N successor) -> EndpointPair.ordered(thisNode, successor)));
     } else {
       resultWithDoubleSelfLoop =
           Iterators.transform(
               orderedNodeConnections.iterator(),
-              new Function<NodeConnection<N>, EndpointPair<N>>() {
-                @Override
-                public EndpointPair<N> apply(NodeConnection<N> connection) {
-                  if (connection instanceof NodeConnection.Succ) {
-                    return EndpointPair.ordered(thisNode, connection.node);
-                  } else {
-                    return EndpointPair.ordered(connection.node, thisNode);
-                  }
+              (NodeConnection<N> connection) -> {
+                if (connection instanceof NodeConnection.Succ) {
+                  return EndpointPair.ordered(thisNode, connection.node);
+                } else {
+                  return EndpointPair.ordered(connection.node, thisNode);
                 }
               });
     }
 
-    final AtomicBoolean alreadySeenSelfLoop = new AtomicBoolean(false);
+    AtomicBoolean alreadySeenSelfLoop = new AtomicBoolean(false);
     return new AbstractIterator<EndpointPair<N>>() {
       @Override
+      @CheckForNull
       protected EndpointPair<N> computeNext() {
         while (resultWithDoubleSelfLoop.hasNext()) {
           EndpointPair<N> edge = resultWithDoubleSelfLoop.next();
@@ -425,6 +419,7 @@ protected EndpointPair<N> computeNext() {
 
   @SuppressWarnings("unchecked")
   @Override
+  @CheckForNull
   public V value(N node) {
     checkNotNull(node);
     Object value = adjacentNodeValues.get(node);
@@ -466,6 +461,7 @@ public void removePredecessor(N node) {
 
   @SuppressWarnings("unchecked")
   @Override
+  @CheckForNull
   public V removeSuccessor(Object node) {
     checkNotNull(node);
     Object previousValue = adjacentNodeValues.get(node);
@@ -489,7 +485,14 @@ public V removeSuccessor(Object node) {
       }
     }
 
-    return (V) removedValue;
+    /*
+     * TODO(cpovirk): `return (V) removedValue` once our checker permits that.
+     *
+     * (We promoted a class of warnings into errors because sometimes they indicate real problems.
+     * But now we need to "undo" some instance of spurious errors, as discussed in
+     * https://github.com/jspecify/checker-framework/issues/8.)
+     */
+    return removedValue == null ? null : (V) removedValue;
   }
 
   @Override
@@ -522,6 +525,7 @@ public void addPredecessor(N node, V unused) {
 
   @SuppressWarnings("unchecked")
   @Override
+  @CheckForNull
   public V addSuccessor(N node, V value) {
     Object previousValue = adjacentNodeValues.put(node, value);
     Object previousSuccessor;
@@ -546,14 +550,15 @@ public V addSuccessor(N node, V value) {
       }
     }
 
-    return (V) previousSuccessor;
+    // See the comment on the similar cast in removeSuccessor.
+    return previousSuccessor == null ? null : (V) previousSuccessor;
   }
 
-  private static boolean isPredecessor(@NullableDecl Object value) {
+  private static boolean isPredecessor(@CheckForNull Object value) {
     return (value == PRED) || (value instanceof PredAndSucc);
   }
 
-  private static boolean isSuccessor(@NullableDecl Object value) {
+  private static boolean isSuccessor(@CheckForNull Object value) {
     return (value != PRED) && (value != null);
   }
 }
diff --git a/android/guava/src/com/google/common/graph/DirectedMultiNetworkConnections.java b/android/guava/src/com/google/common/graph/DirectedMultiNetworkConnections.java
index e1ed3cc4d923..bd0e546f26e3 100644
--- a/android/guava/src/com/google/common/graph/DirectedMultiNetworkConnections.java
+++ b/android/guava/src/com/google/common/graph/DirectedMultiNetworkConnections.java
@@ -30,7 +30,7 @@
 import java.util.HashMap;
 import java.util.Map;
 import java.util.Set;
-import org.checkerframework.checker.nullness.compatqual.NullableDecl;
+import javax.annotation.CheckForNull;
 
 /**
  * An implementation of {@link NetworkConnections} for directed networks with parallel edges.
@@ -39,6 +39,7 @@
  * @param <N> Node parameter type
  * @param <E> Edge parameter type
  */
+@ElementTypesAreNonnullByDefault
 final class DirectedMultiNetworkConnections<N, E> extends AbstractDirectedNetworkConnections<N, E> {
 
   private DirectedMultiNetworkConnections(
@@ -59,7 +60,7 @@ static <N, E> DirectedMultiNetworkConnections<N, E> ofImmutable(
         ImmutableMap.copyOf(inEdges), ImmutableMap.copyOf(outEdges), selfLoopCount);
   }
 
-  @LazyInit private transient Reference<Multiset<N>> predecessorsReference;
+  @CheckForNull @LazyInit private transient Reference<Multiset<N>> predecessorsReference;
 
   @Override
   public Set<N> predecessors() {
@@ -75,7 +76,7 @@ private Multiset<N> predecessorsMultiset() {
     return predecessors;
   }
 
-  @LazyInit private transient Reference<Multiset<N>> successorsReference;
+  @CheckForNull @LazyInit private transient Reference<Multiset<N>> successorsReference;
 
   @Override
   public Set<N> successors() {
@@ -92,7 +93,7 @@ private Multiset<N> successorsMultiset() {
   }
 
   @Override
-  public Set<E> edgesConnecting(final N node) {
+  public Set<E> edgesConnecting(N node) {
     return new MultiEdgesConnecting<E>(outEdgeMap, node) {
       @Override
       public int size() {
@@ -139,8 +140,8 @@ public void addOutEdge(E edge, N node) {
     }
   }
 
-  @NullableDecl
-  private static <T> T getReference(@NullableDecl Reference<T> reference) {
+  @CheckForNull
+  private static <T> T getReference(@CheckForNull Reference<T> reference) {
     return (reference == null) ? null : reference.get();
   }
 }
diff --git a/android/guava/src/com/google/common/graph/DirectedNetworkConnections.java b/android/guava/src/com/google/common/graph/DirectedNetworkConnections.java
index 2a0b010d0998..e1db65708eb0 100644
--- a/android/guava/src/com/google/common/graph/DirectedNetworkConnections.java
+++ b/android/guava/src/com/google/common/graph/DirectedNetworkConnections.java
@@ -32,10 +32,10 @@
  * @param <N> Node parameter type
  * @param <E> Edge parameter type
  */
+@ElementTypesAreNonnullByDefault
 final class DirectedNetworkConnections<N, E> extends AbstractDirectedNetworkConnections<N, E> {
 
-  protected DirectedNetworkConnections(
-      Map<E, N> inEdgeMap, Map<E, N> outEdgeMap, int selfLoopCount) {
+  DirectedNetworkConnections(Map<E, N> inEdgeMap, Map<E, N> outEdgeMap, int selfLoopCount) {
     super(inEdgeMap, outEdgeMap, selfLoopCount);
   }
 
@@ -62,6 +62,6 @@ public Set<N> successors() {
 
   @Override
   public Set<E> edgesConnecting(N node) {
-    return new EdgesConnecting<E>(((BiMap<E, N>) outEdgeMap).inverse(), node);
+    return new EdgesConnecting<>(((BiMap<E, N>) outEdgeMap).inverse(), node);
   }
 }
diff --git a/android/guava/src/com/google/common/graph/EdgesConnecting.java b/android/guava/src/com/google/common/graph/EdgesConnecting.java
index d62eefaee59e..797970ba29c1 100644
--- a/android/guava/src/com/google/common/graph/EdgesConnecting.java
+++ b/android/guava/src/com/google/common/graph/EdgesConnecting.java
@@ -23,7 +23,7 @@
 import com.google.common.collect.UnmodifiableIterator;
 import java.util.AbstractSet;
 import java.util.Map;
-import org.checkerframework.checker.nullness.compatqual.NullableDecl;
+import javax.annotation.CheckForNull;
 
 /**
  * A class to represent the set of edges connecting an (implicit) origin node to a target node.
@@ -34,6 +34,7 @@
  * @author James Sexton
  * @param <E> Edge parameter type
  */
+@ElementTypesAreNonnullByDefault
 final class EdgesConnecting<E> extends AbstractSet<E> {
 
   private final Map<?, E> nodeToOutEdge;
@@ -58,12 +59,12 @@ public int size() {
   }
 
   @Override
-  public boolean contains(@NullableDecl Object edge) {
+  public boolean contains(@CheckForNull Object edge) {
     E connectingEdge = getConnectingEdge();
     return (connectingEdge != null && connectingEdge.equals(edge));
   }
 
-  @NullableDecl
+  @CheckForNull
   private E getConnectingEdge() {
     return nodeToOutEdge.get(targetNode);
   }
diff --git a/android/guava/src/com/google/common/graph/ElementOrder.java b/android/guava/src/com/google/common/graph/ElementOrder.java
index 568fb42b49e2..b5985a280b86 100644
--- a/android/guava/src/com/google/common/graph/ElementOrder.java
+++ b/android/guava/src/com/google/common/graph/ElementOrder.java
@@ -28,7 +28,7 @@
 import com.google.errorprone.annotations.Immutable;
 import java.util.Comparator;
 import java.util.Map;
-import org.checkerframework.checker.nullness.compatqual.NullableDecl;
+import javax.annotation.CheckForNull;
 
 /**
  * Used to represent the order of elements in a data structure that supports different options for
@@ -46,11 +46,12 @@
  */
 @Beta
 @Immutable
+@ElementTypesAreNonnullByDefault
 public final class ElementOrder<T> {
   private final Type type;
 
   @SuppressWarnings("Immutable") // Hopefully the comparator provided is immutable!
-  @NullableDecl
+  @CheckForNull
   private final Comparator<T> comparator;
 
   /**
@@ -71,7 +72,7 @@ public enum Type {
     SORTED
   }
 
-  private ElementOrder(Type type, @NullableDecl Comparator<T> comparator) {
+  private ElementOrder(Type type, @CheckForNull Comparator<T> comparator) {
     this.type = checkNotNull(type);
     this.comparator = comparator;
     checkState((type == Type.SORTED) == (comparator != null));
@@ -79,7 +80,7 @@ private ElementOrder(Type type, @NullableDecl Comparator<T> comparator) {
 
   /** Returns an instance which specifies that no ordering is guaranteed. */
   public static <S> ElementOrder<S> unordered() {
-    return new ElementOrder<S>(Type.UNORDERED, null);
+    return new ElementOrder<>(Type.UNORDERED, null);
   }
 
   /**
@@ -119,19 +120,19 @@ public static <S> ElementOrder<S> unordered() {
    * @since 29.0
    */
   public static <S> ElementOrder<S> stable() {
-    return new ElementOrder<S>(Type.STABLE, null);
+    return new ElementOrder<>(Type.STABLE, null);
   }
 
   /** Returns an instance which specifies that insertion ordering is guaranteed. */
   public static <S> ElementOrder<S> insertion() {
-    return new ElementOrder<S>(Type.INSERTION, null);
+    return new ElementOrder<>(Type.INSERTION, null);
   }
 
   /**
    * Returns an instance which specifies that the natural ordering of the elements is guaranteed.
    */
   public static <S extends Comparable<? super S>> ElementOrder<S> natural() {
-    return new ElementOrder<S>(Type.SORTED, Ordering.<S>natural());
+    return new ElementOrder<>(Type.SORTED, Ordering.<S>natural());
   }
 
   /**
@@ -139,7 +140,7 @@ public static <S extends Comparable<? super S>> ElementOrder<S> natural() {
    * determined by {@code comparator}.
    */
   public static <S> ElementOrder<S> sorted(Comparator<S> comparator) {
-    return new ElementOrder<S>(Type.SORTED, checkNotNull(comparator));
+    return new ElementOrder<>(Type.SORTED, checkNotNull(comparator));
   }
 
   /** Returns the type of ordering used. */
@@ -160,7 +161,7 @@ public Comparator<T> comparator() {
   }
 
   @Override
-  public boolean equals(@NullableDecl Object obj) {
+  public boolean equals(@CheckForNull Object obj) {
     if (obj == this) {
       return true;
     }
diff --git a/android/guava/src/com/google/common/graph/ElementTypesAreNonnullByDefault.java b/android/guava/src/com/google/common/graph/ElementTypesAreNonnullByDefault.java
new file mode 100644
index 000000000000..0798de0c9883
--- /dev/null
+++ b/android/guava/src/com/google/common/graph/ElementTypesAreNonnullByDefault.java
@@ -0,0 +1,41 @@
+/*
+ * Copyright (C) 2021 The Guava Authors
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package com.google.common.graph;
+
+import static java.lang.annotation.ElementType.FIELD;
+import static java.lang.annotation.ElementType.METHOD;
+import static java.lang.annotation.ElementType.PARAMETER;
+import static java.lang.annotation.ElementType.TYPE;
+import static java.lang.annotation.RetentionPolicy.RUNTIME;
+
+import com.google.common.annotations.GwtCompatible;
+import java.lang.annotation.Retention;
+import java.lang.annotation.Target;
+import javax.annotation.Nonnull;
+import javax.annotation.meta.TypeQualifierDefault;
+
+/**
+ * Marks all "top-level" types as non-null in a way that is recognized by Kotlin. Note that this
+ * unfortunately includes type-variable usages, so we also provide {@link ParametricNullness} to
+ * "undo" it as best we can.
+ */
+@GwtCompatible
+@Retention(RUNTIME)
+@Target(TYPE)
+@TypeQualifierDefault({FIELD, METHOD, PARAMETER})
+@Nonnull
+@interface ElementTypesAreNonnullByDefault {}
diff --git a/android/guava/src/com/google/common/graph/EndpointPair.java b/android/guava/src/com/google/common/graph/EndpointPair.java
index 7caa43bb4888..fe2397c6b97b 100644
--- a/android/guava/src/com/google/common/graph/EndpointPair.java
+++ b/android/guava/src/com/google/common/graph/EndpointPair.java
@@ -24,7 +24,7 @@
 import com.google.common.collect.Iterators;
 import com.google.common.collect.UnmodifiableIterator;
 import com.google.errorprone.annotations.Immutable;
-import org.checkerframework.checker.nullness.compatqual.NullableDecl;
+import javax.annotation.CheckForNull;
 
 /**
  * An immutable pair representing the two endpoints of an edge in a graph. The {@link EndpointPair}
@@ -39,6 +39,7 @@
  */
 @Beta
 @Immutable(containerOf = {"N"})
+@ElementTypesAreNonnullByDefault
 public abstract class EndpointPair<N> implements Iterable<N> {
   private final N nodeU;
   private final N nodeV;
@@ -50,13 +51,13 @@ private EndpointPair(N nodeU, N nodeV) {
 
   /** Returns an {@link EndpointPair} representing the endpoints of a directed edge. */
   public static <N> EndpointPair<N> ordered(N source, N target) {
-    return new Ordered<N>(source, target);
+    return new Ordered<>(source, target);
   }
 
   /** Returns an {@link EndpointPair} representing the endpoints of an undirected edge. */
   public static <N> EndpointPair<N> unordered(N nodeU, N nodeV) {
     // Swap nodes on purpose to prevent callers from relying on the "ordering" of an unordered pair.
-    return new Unordered<N>(nodeV, nodeU);
+    return new Unordered<>(nodeV, nodeU);
   }
 
   /** Returns an {@link EndpointPair} representing the endpoints of an edge in {@code graph}. */
@@ -103,8 +104,9 @@ public final N nodeV() {
    * Returns the node that is adjacent to {@code node} along the origin edge.
    *
    * @throws IllegalArgumentException if this {@link EndpointPair} does not contain {@code node}
+   * @since 20.0 (but the argument type was changed from {@code Object} to {@code N} in 31.0)
    */
-  public final N adjacentNode(Object node) {
+  public final N adjacentNode(N node) {
     if (node.equals(nodeU)) {
       return nodeV;
     } else if (node.equals(nodeV)) {
@@ -132,7 +134,7 @@ public final UnmodifiableIterator<N> iterator() {
    * ordered {@link EndpointPair} is never equal to an unordered {@link EndpointPair}.
    */
   @Override
-  public abstract boolean equals(@NullableDecl Object obj);
+  public abstract boolean equals(@CheckForNull Object obj);
 
   /**
    * The hashcode of an ordered {@link EndpointPair} is equal to {@code Objects.hashCode(source(),
@@ -163,7 +165,7 @@ public boolean isOrdered() {
     }
 
     @Override
-    public boolean equals(@NullableDecl Object obj) {
+    public boolean equals(@CheckForNull Object obj) {
       if (obj == this) {
         return true;
       }
@@ -211,7 +213,7 @@ public boolean isOrdered() {
     }
 
     @Override
-    public boolean equals(@NullableDecl Object obj) {
+    public boolean equals(@CheckForNull Object obj) {
       if (obj == this) {
         return true;
       }
diff --git a/android/guava/src/com/google/common/graph/EndpointPairIterator.java b/android/guava/src/com/google/common/graph/EndpointPairIterator.java
index c4e6e073e93d..7096dbe3da2a 100644
--- a/android/guava/src/com/google/common/graph/EndpointPairIterator.java
+++ b/android/guava/src/com/google/common/graph/EndpointPairIterator.java
@@ -17,24 +17,30 @@
 package com.google.common.graph;
 
 import static com.google.common.base.Preconditions.checkState;
+import static java.util.Objects.requireNonNull;
 
 import com.google.common.collect.AbstractIterator;
 import com.google.common.collect.ImmutableSet;
 import com.google.common.collect.Sets;
 import java.util.Iterator;
 import java.util.Set;
+import javax.annotation.CheckForNull;
+import org.checkerframework.checker.nullness.qual.Nullable;
 
 /**
  * A class to facilitate the set returned by {@link Graph#edges()}.
  *
  * @author James Sexton
  */
+@ElementTypesAreNonnullByDefault
 abstract class EndpointPairIterator<N> extends AbstractIterator<EndpointPair<N>> {
   private final BaseGraph<N> graph;
   private final Iterator<N> nodeIterator;
 
-  protected N node = null; // null is safe as an initial value because graphs don't allow null nodes
-  protected Iterator<N> successorIterator = ImmutableSet.<N>of().iterator();
+  @CheckForNull
+  N node = null; // null is safe as an initial value because graphs don't allow null nodes
+
+  Iterator<N> successorIterator = ImmutableSet.<N>of().iterator();
 
   static <N> EndpointPairIterator<N> of(BaseGraph<N> graph) {
     return graph.isDirected() ? new Directed<N>(graph) : new Undirected<N>(graph);
@@ -49,7 +55,7 @@ private EndpointPairIterator(BaseGraph<N> graph) {
    * Called after {@link #successorIterator} is exhausted. Advances {@link #node} to the next node
    * and updates {@link #successorIterator} to iterate through the successors of {@link #node}.
    */
-  protected final boolean advance() {
+  final boolean advance() {
     checkState(!successorIterator.hasNext());
     if (!nodeIterator.hasNext()) {
       return false;
@@ -69,10 +75,12 @@ private Directed(BaseGraph<N> graph) {
     }
 
     @Override
+    @CheckForNull
     protected EndpointPair<N> computeNext() {
       while (true) {
         if (successorIterator.hasNext()) {
-          return EndpointPair.ordered(node, successorIterator.next());
+          // requireNonNull is safe because successorIterator is empty until we set this.node.
+          return EndpointPair.ordered(requireNonNull(node), successorIterator.next());
         }
         if (!advance()) {
           return endOfData();
@@ -108,20 +116,28 @@ protected EndpointPair<N> computeNext() {
    * </pre>
    */
   private static final class Undirected<N> extends EndpointPairIterator<N> {
-    private Set<N> visitedNodes;
+    // It's a little weird that we add `null` to this set, but it makes for slightly simpler code.
+    @CheckForNull private Set<@Nullable N> visitedNodes;
 
     private Undirected(BaseGraph<N> graph) {
       super(graph);
-      this.visitedNodes = Sets.newHashSetWithExpectedSize(graph.nodes().size());
+      this.visitedNodes = Sets.newHashSetWithExpectedSize(graph.nodes().size() + 1);
     }
 
     @Override
+    @CheckForNull
     protected EndpointPair<N> computeNext() {
       while (true) {
+        /*
+         * requireNonNull is safe because visitedNodes isn't cleared until this method calls
+         * endOfData() (after which this method is never called again).
+         */
+        requireNonNull(visitedNodes);
         while (successorIterator.hasNext()) {
           N otherNode = successorIterator.next();
           if (!visitedNodes.contains(otherNode)) {
-            return EndpointPair.unordered(node, otherNode);
+            // requireNonNull is safe because successorIterator is empty until we set node.
+            return EndpointPair.unordered(requireNonNull(node), otherNode);
           }
         }
         // Add to visited set *after* processing neighbors so we still include self-loops.
diff --git a/android/guava/src/com/google/common/graph/ForwardingGraph.java b/android/guava/src/com/google/common/graph/ForwardingGraph.java
index 4a3ab8c77b3b..f4ddf425db29 100644
--- a/android/guava/src/com/google/common/graph/ForwardingGraph.java
+++ b/android/guava/src/com/google/common/graph/ForwardingGraph.java
@@ -24,9 +24,10 @@
  *
  * @author James Sexton
  */
+@ElementTypesAreNonnullByDefault
 abstract class ForwardingGraph<N> extends AbstractGraph<N> {
 
-  protected abstract BaseGraph<N> delegate();
+  abstract BaseGraph<N> delegate();
 
   @Override
   public Set<N> nodes() {
diff --git a/android/guava/src/com/google/common/graph/ForwardingNetwork.java b/android/guava/src/com/google/common/graph/ForwardingNetwork.java
index 89766dc984b6..fd211524efb0 100644
--- a/android/guava/src/com/google/common/graph/ForwardingNetwork.java
+++ b/android/guava/src/com/google/common/graph/ForwardingNetwork.java
@@ -17,6 +17,7 @@
 package com.google.common.graph;
 
 import java.util.Set;
+import javax.annotation.CheckForNull;
 
 /**
  * A class to allow {@link Network} implementations to be backed by a provided delegate. This is not
@@ -25,9 +26,10 @@
  * @author James Sexton
  * @author Joshua O'Madadhain
  */
+@ElementTypesAreNonnullByDefault
 abstract class ForwardingNetwork<N, E> extends AbstractNetwork<N, E> {
 
-  protected abstract Network<N, E> delegate();
+  abstract Network<N, E> delegate();
 
   @Override
   public Set<N> nodes() {
@@ -130,11 +132,13 @@ public Set<E> edgesConnecting(EndpointPair<N> endpoints) {
   }
 
   @Override
+  @CheckForNull
   public E edgeConnectingOrNull(N nodeU, N nodeV) {
     return delegate().edgeConnectingOrNull(nodeU, nodeV);
   }
 
   @Override
+  @CheckForNull
   public E edgeConnectingOrNull(EndpointPair<N> endpoints) {
     return delegate().edgeConnectingOrNull(endpoints);
   }
diff --git a/android/guava/src/com/google/common/graph/ForwardingValueGraph.java b/android/guava/src/com/google/common/graph/ForwardingValueGraph.java
index 2507890ea480..70ed6e5595f3 100644
--- a/android/guava/src/com/google/common/graph/ForwardingValueGraph.java
+++ b/android/guava/src/com/google/common/graph/ForwardingValueGraph.java
@@ -17,7 +17,7 @@
 package com.google.common.graph;
 
 import java.util.Set;
-import org.checkerframework.checker.nullness.compatqual.NullableDecl;
+import javax.annotation.CheckForNull;
 
 /**
  * A class to allow {@link ValueGraph} implementations to be backed by a provided delegate. This is
@@ -26,9 +26,10 @@
  * @author James Sexton
  * @author Joshua O'Madadhain
  */
+@ElementTypesAreNonnullByDefault
 abstract class ForwardingValueGraph<N, V> extends AbstractValueGraph<N, V> {
 
-  protected abstract ValueGraph<N, V> delegate();
+  abstract ValueGraph<N, V> delegate();
 
   @Override
   public Set<N> nodes() {
@@ -105,14 +106,14 @@ public boolean hasEdgeConnecting(EndpointPair<N> endpoints) {
   }
 
   @Override
-  @NullableDecl
-  public V edgeValueOrDefault(N nodeU, N nodeV, @NullableDecl V defaultValue) {
+  @CheckForNull
+  public V edgeValueOrDefault(N nodeU, N nodeV, @CheckForNull V defaultValue) {
     return delegate().edgeValueOrDefault(nodeU, nodeV, defaultValue);
   }
 
   @Override
-  @NullableDecl
-  public V edgeValueOrDefault(EndpointPair<N> endpoints, @NullableDecl V defaultValue) {
+  @CheckForNull
+  public V edgeValueOrDefault(EndpointPair<N> endpoints, @CheckForNull V defaultValue) {
     return delegate().edgeValueOrDefault(endpoints, defaultValue);
   }
 }
diff --git a/android/guava/src/com/google/common/graph/Graph.java b/android/guava/src/com/google/common/graph/Graph.java
index 8ed35fb9afa0..5dc0e71faf6d 100644
--- a/android/guava/src/com/google/common/graph/Graph.java
+++ b/android/guava/src/com/google/common/graph/Graph.java
@@ -20,7 +20,7 @@
 import com.google.errorprone.annotations.DoNotMock;
 import java.util.Collection;
 import java.util.Set;
-import org.checkerframework.checker.nullness.compatqual.NullableDecl;
+import javax.annotation.CheckForNull;
 
 /**
  * An interface for <a
@@ -103,6 +103,7 @@
  */
 @Beta
 @DoNotMock("Use GraphBuilder to create a real instance")
+@ElementTypesAreNonnullByDefault
 public interface Graph<N> extends BaseGraph<N> {
   //
   // Graph-level accessors
@@ -289,7 +290,7 @@ public interface Graph<N> extends BaseGraph<N> {
    * <p>A reference implementation of this is provided by {@link AbstractGraph#equals(Object)}.
    */
   @Override
-  boolean equals(@NullableDecl Object object);
+  boolean equals(@CheckForNull Object object);
 
   /**
    * Returns the hash code for this graph. The hash code of a graph is defined as the hash code of
diff --git a/android/guava/src/com/google/common/graph/GraphBuilder.java b/android/guava/src/com/google/common/graph/GraphBuilder.java
index f00d7b1f93be..8c0871b467d1 100644
--- a/android/guava/src/com/google/common/graph/GraphBuilder.java
+++ b/android/guava/src/com/google/common/graph/GraphBuilder.java
@@ -64,6 +64,7 @@
  */
 @Beta
 @DoNotMock
+@ElementTypesAreNonnullByDefault
 public final class GraphBuilder<N> extends AbstractGraphBuilder<N> {
 
   /** Creates a new instance with the specified edge directionality. */
@@ -170,7 +171,7 @@ public <N1 extends N> GraphBuilder<N1> incidentEdgeOrder(ElementOrder<N1> incide
 
   /** Returns an empty {@link MutableGraph} with the properties of this {@link GraphBuilder}. */
   public <N1 extends N> MutableGraph<N1> build() {
-    return new StandardMutableGraph<N1>(this);
+    return new StandardMutableGraph<>(this);
   }
 
   GraphBuilder<N> copy() {
diff --git a/android/guava/src/com/google/common/graph/GraphConnections.java b/android/guava/src/com/google/common/graph/GraphConnections.java
index d783c782616c..7d4f8f0cf02b 100644
--- a/android/guava/src/com/google/common/graph/GraphConnections.java
+++ b/android/guava/src/com/google/common/graph/GraphConnections.java
@@ -19,7 +19,7 @@
 import com.google.errorprone.annotations.CanIgnoreReturnValue;
 import java.util.Iterator;
 import java.util.Set;
-import org.checkerframework.checker.nullness.compatqual.NullableDecl;
+import javax.annotation.CheckForNull;
 
 /**
  * An interface for representing and manipulating an origin node's adjacent nodes and edge values in
@@ -29,6 +29,7 @@
  * @param <N> Node parameter type
  * @param <V> Value parameter type
  */
+@ElementTypesAreNonnullByDefault
 interface GraphConnections<N, V> {
 
   Set<N> adjacentNodes();
@@ -48,7 +49,7 @@ interface GraphConnections<N, V> {
    * Returns the value associated with the edge connecting the origin node to {@code node}, or null
    * if there is no such edge.
    */
-  @NullableDecl
+  @CheckForNull
   V value(N node);
 
   /** Remove {@code node} from the set of predecessors. */
@@ -59,6 +60,7 @@ interface GraphConnections<N, V> {
    * the edge connecting the two nodes.
    */
   @CanIgnoreReturnValue
+  @CheckForNull
   V removeSuccessor(N node);
 
   /**
@@ -73,5 +75,6 @@ interface GraphConnections<N, V> {
    * the value previously associated with the edge connecting the two nodes.
    */
   @CanIgnoreReturnValue
+  @CheckForNull
   V addSuccessor(N node, V value);
 }
diff --git a/android/guava/src/com/google/common/graph/GraphConstants.java b/android/guava/src/com/google/common/graph/GraphConstants.java
index 224c6d2486f7..ae224fdd2252 100644
--- a/android/guava/src/com/google/common/graph/GraphConstants.java
+++ b/android/guava/src/com/google/common/graph/GraphConstants.java
@@ -16,7 +16,9 @@
 
 package com.google.common.graph;
 
+
 /** A utility class to hold various constants used by the Guava Graph library. */
+@ElementTypesAreNonnullByDefault
 final class GraphConstants {
 
   private GraphConstants() {}
diff --git a/android/guava/src/com/google/common/graph/Graphs.java b/android/guava/src/com/google/common/graph/Graphs.java
index c278c7198eb1..bad8580ac859 100644
--- a/android/guava/src/com/google/common/graph/Graphs.java
+++ b/android/guava/src/com/google/common/graph/Graphs.java
@@ -18,6 +18,7 @@
 
 import static com.google.common.base.Preconditions.checkArgument;
 import static com.google.common.graph.GraphConstants.NODE_NOT_IN_GRAPH;
+import static java.util.Objects.requireNonNull;
 
 import com.google.common.annotations.Beta;
 import com.google.common.base.Function;
@@ -32,7 +33,7 @@
 import java.util.Iterator;
 import java.util.Map;
 import java.util.Set;
-import org.checkerframework.checker.nullness.compatqual.NullableDecl;
+import javax.annotation.CheckForNull;
 
 /**
  * Static utility methods for {@link Graph}, {@link ValueGraph}, and {@link Network} instances.
@@ -42,6 +43,7 @@
  * @since 20.0
  */
 @Beta
+@ElementTypesAreNonnullByDefault
 public final class Graphs {
 
   private Graphs() {}
@@ -101,7 +103,7 @@ private static <N> boolean subgraphHasCycle(
       Graph<N> graph,
       Map<Object, NodeVisitState> visitedNodes,
       N node,
-      @NullableDecl N previousNode) {
+      @CheckForNull N previousNode) {
     NodeVisitState state = visitedNodes.get(node);
     if (state == NodeVisitState.COMPLETE) {
       return false;
@@ -128,7 +130,7 @@ && subgraphHasCycle(graph, visitedNodes, nextNode, node)) {
    * from B to A).
    */
   private static boolean canTraverseWithoutReusingEdge(
-      Graph<?> graph, Object nextNode, @NullableDecl Object previousNode) {
+      Graph<?> graph, Object nextNode, @CheckForNull Object previousNode) {
     if (graph.isDirected() || !Objects.equal(previousNode, nextNode)) {
       return true;
     }
@@ -265,7 +267,7 @@ private static class TransposedGraph<N> extends ForwardingGraph<N> {
     }
 
     @Override
-    protected Graph<N> delegate() {
+    Graph<N> delegate() {
       return graph;
     }
 
@@ -327,7 +329,7 @@ private static class TransposedValueGraph<N, V> extends ForwardingValueGraph<N,
     }
 
     @Override
-    protected ValueGraph<N, V> delegate() {
+    ValueGraph<N, V> delegate() {
       return graph;
     }
 
@@ -362,14 +364,14 @@ public boolean hasEdgeConnecting(EndpointPair<N> endpoints) {
     }
 
     @Override
-    @NullableDecl
-    public V edgeValueOrDefault(N nodeU, N nodeV, @NullableDecl V defaultValue) {
+    @CheckForNull
+    public V edgeValueOrDefault(N nodeU, N nodeV, @CheckForNull V defaultValue) {
       return delegate().edgeValueOrDefault(nodeV, nodeU, defaultValue); // transpose
     }
 
     @Override
-    @NullableDecl
-    public V edgeValueOrDefault(EndpointPair<N> endpoints, @NullableDecl V defaultValue) {
+    @CheckForNull
+    public V edgeValueOrDefault(EndpointPair<N> endpoints, @CheckForNull V defaultValue) {
       return delegate().edgeValueOrDefault(transpose(endpoints), defaultValue);
     }
   }
@@ -382,7 +384,7 @@ private static class TransposedNetwork<N, E> extends ForwardingNetwork<N, E> {
     }
 
     @Override
-    protected Network<N, E> delegate() {
+    Network<N, E> delegate() {
       return network;
     }
 
@@ -433,11 +435,13 @@ public Set<E> edgesConnecting(EndpointPair<N> endpoints) {
     }
 
     @Override
+    @CheckForNull
     public E edgeConnectingOrNull(N nodeU, N nodeV) {
       return delegate().edgeConnectingOrNull(nodeV, nodeU); // transpose
     }
 
     @Override
+    @CheckForNull
     public E edgeConnectingOrNull(EndpointPair<N> endpoints) {
       return delegate().edgeConnectingOrNull(transpose(endpoints));
     }
@@ -500,8 +504,11 @@ public static <N, V> MutableValueGraph<N, V> inducedSubgraph(
     for (N node : subgraph.nodes()) {
       for (N successorNode : graph.successors(node)) {
         if (subgraph.nodes().contains(successorNode)) {
+          // requireNonNull is safe because the endpoint pair comes from the graph.
           subgraph.putEdgeValue(
-              node, successorNode, graph.edgeValueOrDefault(node, successorNode, null));
+              node,
+              successorNode,
+              requireNonNull(graph.edgeValueOrDefault(node, successorNode, null)));
         }
       }
     }
@@ -556,8 +563,11 @@ public static <N, V> MutableValueGraph<N, V> copyOf(ValueGraph<N, V> graph) {
       copy.addNode(node);
     }
     for (EndpointPair<N> edge : graph.edges()) {
+      // requireNonNull is safe because the endpoint pair comes from the graph.
       copy.putEdgeValue(
-          edge.nodeU(), edge.nodeV(), graph.edgeValueOrDefault(edge.nodeU(), edge.nodeV(), null));
+          edge.nodeU(),
+          edge.nodeV(),
+          requireNonNull(graph.edgeValueOrDefault(edge.nodeU(), edge.nodeV(), null)));
     }
     return copy;
   }
diff --git a/android/guava/src/com/google/common/graph/ImmutableGraph.java b/android/guava/src/com/google/common/graph/ImmutableGraph.java
index 4027ca83de29..f829e9699993 100644
--- a/android/guava/src/com/google/common/graph/ImmutableGraph.java
+++ b/android/guava/src/com/google/common/graph/ImmutableGraph.java
@@ -45,6 +45,7 @@
  */
 @Beta
 @Immutable(containerOf = {"N"})
+@ElementTypesAreNonnullByDefault
 public class ImmutableGraph<N> extends ForwardingGraph<N> {
   @SuppressWarnings("Immutable") // The backing graph must be immutable.
   private final BaseGraph<N> backingGraph;
@@ -86,7 +87,7 @@ private static <N> ImmutableMap<N, GraphConnections<N, Presence>> getNodeConnect
     for (N node : graph.nodes()) {
       nodeConnections.put(node, connectionsOf(graph, node));
     }
-    return nodeConnections.build();
+    return nodeConnections.buildOrThrow();
   }
 
   @SuppressWarnings("unchecked")
@@ -100,7 +101,7 @@ private static <N> GraphConnections<N, Presence> connectionsOf(Graph<N> graph, N
   }
 
   @Override
-  protected BaseGraph<N> delegate() {
+  BaseGraph<N> delegate() {
     return backingGraph;
   }
 
diff --git a/android/guava/src/com/google/common/graph/ImmutableNetwork.java b/android/guava/src/com/google/common/graph/ImmutableNetwork.java
index b35d7220817d..c29f8a392813 100644
--- a/android/guava/src/com/google/common/graph/ImmutableNetwork.java
+++ b/android/guava/src/com/google/common/graph/ImmutableNetwork.java
@@ -46,6 +46,7 @@
 @Beta
 @Immutable(containerOf = {"N", "E"})
 @SuppressWarnings("Immutable") // Extends StandardNetwork but uses ImmutableMaps.
+@ElementTypesAreNonnullByDefault
 public final class ImmutableNetwork<N, E> extends StandardNetwork<N, E> {
 
   private ImmutableNetwork(Network<N, E> network) {
@@ -72,7 +73,7 @@ public static <N, E> ImmutableNetwork<N, E> copyOf(ImmutableNetwork<N, E> networ
 
   @Override
   public ImmutableGraph<N> asGraph() {
-    return new ImmutableGraph<N>(super.asGraph()); // safe because the view is effectively immutable
+    return new ImmutableGraph<>(super.asGraph()); // safe because the view is effectively immutable
   }
 
   private static <N, E> Map<N, NetworkConnections<N, E>> getNodeConnections(Network<N, E> network) {
@@ -83,7 +84,7 @@ private static <N, E> Map<N, NetworkConnections<N, E>> getNodeConnections(Networ
     for (N node : network.nodes()) {
       nodeConnections.put(node, connectionsOf(network, node));
     }
-    return nodeConnections.build();
+    return nodeConnections.buildOrThrow();
   }
 
   private static <N, E> Map<E, N> getEdgeToReferenceNode(Network<N, E> network) {
@@ -94,7 +95,7 @@ private static <N, E> Map<E, N> getEdgeToReferenceNode(Network<N, E> network) {
     for (E edge : network.edges()) {
       edgeToReferenceNode.put(edge, network.incidentNodes(edge).nodeU());
     }
-    return edgeToReferenceNode.build();
+    return edgeToReferenceNode.buildOrThrow();
   }
 
   private static <N, E> NetworkConnections<N, E> connectionsOf(Network<N, E> network, N node) {
@@ -114,31 +115,16 @@ private static <N, E> NetworkConnections<N, E> connectionsOf(Network<N, E> netwo
     }
   }
 
-  private static <N, E> Function<E, N> sourceNodeFn(final Network<N, E> network) {
-    return new Function<E, N>() {
-      @Override
-      public N apply(E edge) {
-        return network.incidentNodes(edge).source();
-      }
-    };
+  private static <N, E> Function<E, N> sourceNodeFn(Network<N, E> network) {
+    return (E edge) -> network.incidentNodes(edge).source();
   }
 
-  private static <N, E> Function<E, N> targetNodeFn(final Network<N, E> network) {
-    return new Function<E, N>() {
-      @Override
-      public N apply(E edge) {
-        return network.incidentNodes(edge).target();
-      }
-    };
+  private static <N, E> Function<E, N> targetNodeFn(Network<N, E> network) {
+    return (E edge) -> network.incidentNodes(edge).target();
   }
 
-  private static <N, E> Function<E, N> adjacentNodeFn(final Network<N, E> network, final N node) {
-    return new Function<E, N>() {
-      @Override
-      public N apply(E edge) {
-        return network.incidentNodes(edge).adjacentNode(node);
-      }
-    };
+  private static <N, E> Function<E, N> adjacentNodeFn(Network<N, E> network, N node) {
+    return (E edge) -> network.incidentNodes(edge).adjacentNode(node);
   }
 
   /**
diff --git a/android/guava/src/com/google/common/graph/ImmutableValueGraph.java b/android/guava/src/com/google/common/graph/ImmutableValueGraph.java
index f2e2386340eb..eb17067fca43 100644
--- a/android/guava/src/com/google/common/graph/ImmutableValueGraph.java
+++ b/android/guava/src/com/google/common/graph/ImmutableValueGraph.java
@@ -17,6 +17,7 @@
 package com.google.common.graph;
 
 import static com.google.common.base.Preconditions.checkNotNull;
+import static java.util.Objects.requireNonNull;
 
 import com.google.common.annotations.Beta;
 import com.google.common.base.Function;
@@ -43,6 +44,7 @@
 @Beta
 @Immutable(containerOf = {"N", "V"})
 @SuppressWarnings("Immutable") // Extends StandardValueGraph but uses ImmutableMaps.
+@ElementTypesAreNonnullByDefault
 public final class ImmutableValueGraph<N, V> extends StandardValueGraph<N, V> {
 
   private ImmutableValueGraph(ValueGraph<N, V> graph) {
@@ -73,7 +75,7 @@ public ElementOrder<N> incidentEdgeOrder() {
 
   @Override
   public ImmutableGraph<N> asGraph() {
-    return new ImmutableGraph<N>(this); // safe because the view is effectively immutable
+    return new ImmutableGraph<>(this); // safe because the view is effectively immutable
   }
 
   private static <N, V> ImmutableMap<N, GraphConnections<N, V>> getNodeConnections(
@@ -85,18 +87,14 @@ private static <N, V> ImmutableMap<N, GraphConnections<N, V>> getNodeConnections
     for (N node : graph.nodes()) {
       nodeConnections.put(node, connectionsOf(graph, node));
     }
-    return nodeConnections.build();
+    return nodeConnections.buildOrThrow();
   }
 
-  private static <N, V> GraphConnections<N, V> connectionsOf(
-      final ValueGraph<N, V> graph, final N node) {
+  private static <N, V> GraphConnections<N, V> connectionsOf(ValueGraph<N, V> graph, N node) {
     Function<N, V> successorNodeToValueFn =
-        new Function<N, V>() {
-          @Override
-          public V apply(N successorNode) {
-            return graph.edgeValueOrDefault(node, successorNode, null);
-          }
-        };
+        (N successorNode) ->
+            // requireNonNull is safe because the endpoint pair comes from the graph.
+            requireNonNull(graph.edgeValueOrDefault(node, successorNode, null));
     return graph.isDirected()
         ? DirectedGraphConnections.ofImmutable(
             node, graph.incidentEdges(node), successorNodeToValueFn)
diff --git a/android/guava/src/com/google/common/graph/IncidentEdgeSet.java b/android/guava/src/com/google/common/graph/IncidentEdgeSet.java
index ba91c3b861c3..ac94b65779d4 100644
--- a/android/guava/src/com/google/common/graph/IncidentEdgeSet.java
+++ b/android/guava/src/com/google/common/graph/IncidentEdgeSet.java
@@ -18,15 +18,16 @@
 
 import java.util.AbstractSet;
 import java.util.Set;
-import org.checkerframework.checker.nullness.compatqual.NullableDecl;
+import javax.annotation.CheckForNull;
 
 /**
  * Abstract base class for an incident edges set that allows different implementations of {@link
  * AbstractSet#iterator()}.
  */
+@ElementTypesAreNonnullByDefault
 abstract class IncidentEdgeSet<N> extends AbstractSet<EndpointPair<N>> {
-  protected final N node;
-  protected final BaseGraph<N> graph;
+  final N node;
+  final BaseGraph<N> graph;
 
   IncidentEdgeSet(BaseGraph<N> graph, N node) {
     this.graph = graph;
@@ -34,7 +35,7 @@ abstract class IncidentEdgeSet<N> extends AbstractSet<EndpointPair<N>> {
   }
 
   @Override
-  public boolean remove(Object o) {
+  public boolean remove(@CheckForNull Object o) {
     throw new UnsupportedOperationException();
   }
 
@@ -50,7 +51,7 @@ public int size() {
   }
 
   @Override
-  public boolean contains(@NullableDecl Object obj) {
+  public boolean contains(@CheckForNull Object obj) {
     if (!(obj instanceof EndpointPair)) {
       return false;
     }
diff --git a/android/guava/src/com/google/common/graph/MapIteratorCache.java b/android/guava/src/com/google/common/graph/MapIteratorCache.java
index e53a7cd403a4..05cdde8c3f12 100644
--- a/android/guava/src/com/google/common/graph/MapIteratorCache.java
+++ b/android/guava/src/com/google/common/graph/MapIteratorCache.java
@@ -25,7 +25,7 @@
 import java.util.Map;
 import java.util.Map.Entry;
 import java.util.Set;
-import org.checkerframework.checker.nullness.compatqual.NullableDecl;
+import javax.annotation.CheckForNull;
 
 /**
  * A map-like data structure that wraps a backing map and caches values while iterating through
@@ -41,6 +41,7 @@
  *
  * @author James Sexton
  */
+@ElementTypesAreNonnullByDefault
 class MapIteratorCache<K, V> {
   private final Map<K, V> backingMap;
 
@@ -53,47 +54,61 @@ class MapIteratorCache<K, V> {
    * while writing to it in another. All it does is help with _reading_ from multiple threads
    * concurrently. For more information, see AbstractNetworkTest.concurrentIteration.
    */
-  @NullableDecl private transient volatile Entry<K, V> cacheEntry;
+  @CheckForNull private transient volatile Entry<K, V> cacheEntry;
 
   MapIteratorCache(Map<K, V> backingMap) {
     this.backingMap = checkNotNull(backingMap);
   }
 
   @CanIgnoreReturnValue
-  public final V put(@NullableDecl K key, @NullableDecl V value) {
+  @CheckForNull
+  final V put(K key, V value) {
+    checkNotNull(key);
+    checkNotNull(value);
     clearCache();
     return backingMap.put(key, value);
   }
 
   @CanIgnoreReturnValue
-  public final V remove(@NullableDecl Object key) {
+  @CheckForNull
+  final V remove(Object key) {
+    checkNotNull(key);
     clearCache();
     return backingMap.remove(key);
   }
 
-  public final void clear() {
+  final void clear() {
     clearCache();
     backingMap.clear();
   }
 
-  public V get(@NullableDecl Object key) {
+  @CheckForNull
+  V get(Object key) {
+    checkNotNull(key);
     V value = getIfCached(key);
-    return (value != null) ? value : getWithoutCaching(key);
+    // TODO(b/192579700): Use a ternary once it no longer confuses our nullness checker.
+    if (value == null) {
+      return getWithoutCaching(key);
+    } else {
+      return value;
+    }
   }
 
-  public final V getWithoutCaching(@NullableDecl Object key) {
+  @CheckForNull
+  final V getWithoutCaching(Object key) {
+    checkNotNull(key);
     return backingMap.get(key);
   }
 
-  public final boolean containsKey(@NullableDecl Object key) {
+  final boolean containsKey(@CheckForNull Object key) {
     return getIfCached(key) != null || backingMap.containsKey(key);
   }
 
-  public final Set<K> unmodifiableKeySet() {
+  final Set<K> unmodifiableKeySet() {
     return new AbstractSet<K>() {
       @Override
       public UnmodifiableIterator<K> iterator() {
-        final Iterator<Entry<K, V>> entryIterator = backingMap.entrySet().iterator();
+        Iterator<Entry<K, V>> entryIterator = backingMap.entrySet().iterator();
 
         return new UnmodifiableIterator<K>() {
           @Override
@@ -116,15 +131,16 @@ public int size() {
       }
 
       @Override
-      public boolean contains(@NullableDecl Object key) {
+      public boolean contains(@CheckForNull Object key) {
         return containsKey(key);
       }
     };
   }
 
-  // Internal methods ('protected' is still package-visible, but treat as only subclass-visible)
+  // Internal methods (package-visible, but treat as only subclass-visible)
 
-  protected V getIfCached(@NullableDecl Object key) {
+  @CheckForNull
+  V getIfCached(@CheckForNull Object key) {
     Entry<K, V> entry = cacheEntry; // store local reference for thread-safety
 
     // Check cache. We use == on purpose because it's cheaper and a cache miss is ok.
@@ -134,7 +150,7 @@ protected V getIfCached(@NullableDecl Object key) {
     return null;
   }
 
-  protected void clearCache() {
+  void clearCache() {
     cacheEntry = null;
   }
 }
diff --git a/android/guava/src/com/google/common/graph/MapRetrievalCache.java b/android/guava/src/com/google/common/graph/MapRetrievalCache.java
index 01c45f7d8536..ada78f28414d 100644
--- a/android/guava/src/com/google/common/graph/MapRetrievalCache.java
+++ b/android/guava/src/com/google/common/graph/MapRetrievalCache.java
@@ -16,8 +16,10 @@
 
 package com.google.common.graph;
 
+import static com.google.common.base.Preconditions.checkNotNull;
+
 import java.util.Map;
-import org.checkerframework.checker.nullness.compatqual.NullableDecl;
+import javax.annotation.CheckForNull;
 
 /**
  * A {@link MapIteratorCache} that adds additional caching. In addition to the caching provided by
@@ -25,10 +27,11 @@
  *
  * @author James Sexton
  */
-class MapRetrievalCache<K, V> extends MapIteratorCache<K, V> {
+@ElementTypesAreNonnullByDefault
+final class MapRetrievalCache<K, V> extends MapIteratorCache<K, V> {
   // See the note about volatile in the superclass.
-  @NullableDecl private transient volatile CacheEntry<K, V> cacheEntry1;
-  @NullableDecl private transient volatile CacheEntry<K, V> cacheEntry2;
+  @CheckForNull private transient volatile CacheEntry<K, V> cacheEntry1;
+  @CheckForNull private transient volatile CacheEntry<K, V> cacheEntry2;
 
   MapRetrievalCache(Map<K, V> backingMap) {
     super(backingMap);
@@ -36,7 +39,9 @@ class MapRetrievalCache<K, V> extends MapIteratorCache<K, V> {
 
   @SuppressWarnings("unchecked") // Safe because we only cast if key is found in map.
   @Override
-  public V get(@NullableDecl Object key) {
+  @CheckForNull
+  V get(Object key) {
+    checkNotNull(key);
     V value = getIfCached(key);
     if (value != null) {
       return value;
@@ -49,10 +54,11 @@ public V get(@NullableDecl Object key) {
     return value;
   }
 
-  // Internal methods ('protected' is still package-visible, but treat as only subclass-visible)
+  // Internal methods (package-visible, but treat as only subclass-visible)
 
   @Override
-  protected V getIfCached(@NullableDecl Object key) {
+  @CheckForNull
+  V getIfCached(@CheckForNull Object key) {
     V value = super.getIfCached(key);
     if (value != null) {
       return value;
@@ -78,7 +84,7 @@ protected V getIfCached(@NullableDecl Object key) {
   }
 
   @Override
-  protected void clearCache() {
+  void clearCache() {
     super.clearCache();
     cacheEntry1 = null;
     cacheEntry2 = null;
diff --git a/android/guava/src/com/google/common/graph/MultiEdgesConnecting.java b/android/guava/src/com/google/common/graph/MultiEdgesConnecting.java
index 916c6dd09a9e..620f986a555a 100644
--- a/android/guava/src/com/google/common/graph/MultiEdgesConnecting.java
+++ b/android/guava/src/com/google/common/graph/MultiEdgesConnecting.java
@@ -24,7 +24,7 @@
 import java.util.Iterator;
 import java.util.Map;
 import java.util.Map.Entry;
-import org.checkerframework.checker.nullness.compatqual.NullableDecl;
+import javax.annotation.CheckForNull;
 
 /**
  * A class to represent the set of edges connecting an (implicit) origin node to a target node.
@@ -35,6 +35,7 @@
  * @author James Sexton
  * @param <E> Edge parameter type
  */
+@ElementTypesAreNonnullByDefault
 abstract class MultiEdgesConnecting<E> extends AbstractSet<E> {
 
   private final Map<E, ?> outEdgeToNode;
@@ -47,9 +48,10 @@ abstract class MultiEdgesConnecting<E> extends AbstractSet<E> {
 
   @Override
   public UnmodifiableIterator<E> iterator() {
-    final Iterator<? extends Entry<E, ?>> entries = outEdgeToNode.entrySet().iterator();
+    Iterator<? extends Entry<E, ?>> entries = outEdgeToNode.entrySet().iterator();
     return new AbstractIterator<E>() {
       @Override
+      @CheckForNull
       protected E computeNext() {
         while (entries.hasNext()) {
           Entry<E, ?> entry = entries.next();
@@ -63,7 +65,7 @@ protected E computeNext() {
   }
 
   @Override
-  public boolean contains(@NullableDecl Object edge) {
+  public boolean contains(@CheckForNull Object edge) {
     return targetNode.equals(outEdgeToNode.get(edge));
   }
 }
diff --git a/android/guava/src/com/google/common/graph/MutableGraph.java b/android/guava/src/com/google/common/graph/MutableGraph.java
index 8324079f6c08..b1f3359cab58 100644
--- a/android/guava/src/com/google/common/graph/MutableGraph.java
+++ b/android/guava/src/com/google/common/graph/MutableGraph.java
@@ -29,6 +29,7 @@
  * @since 20.0
  */
 @Beta
+@ElementTypesAreNonnullByDefault
 public interface MutableGraph<N> extends Graph<N> {
 
   /**
diff --git a/android/guava/src/com/google/common/graph/MutableNetwork.java b/android/guava/src/com/google/common/graph/MutableNetwork.java
index d702903604cf..64acb13162af 100644
--- a/android/guava/src/com/google/common/graph/MutableNetwork.java
+++ b/android/guava/src/com/google/common/graph/MutableNetwork.java
@@ -30,6 +30,7 @@
  * @since 20.0
  */
 @Beta
+@ElementTypesAreNonnullByDefault
 public interface MutableNetwork<N, E> extends Network<N, E> {
 
   /**
diff --git a/android/guava/src/com/google/common/graph/MutableValueGraph.java b/android/guava/src/com/google/common/graph/MutableValueGraph.java
index 70b286dee185..f32d2ee7a38c 100644
--- a/android/guava/src/com/google/common/graph/MutableValueGraph.java
+++ b/android/guava/src/com/google/common/graph/MutableValueGraph.java
@@ -18,6 +18,7 @@
 
 import com.google.common.annotations.Beta;
 import com.google.errorprone.annotations.CanIgnoreReturnValue;
+import javax.annotation.CheckForNull;
 
 /**
  * A subinterface of {@link ValueGraph} which adds mutation methods. When mutation is not required,
@@ -29,6 +30,7 @@
  * @since 20.0
  */
 @Beta
+@ElementTypesAreNonnullByDefault
 public interface MutableValueGraph<N, V> extends ValueGraph<N, V> {
 
   /**
@@ -59,6 +61,7 @@ public interface MutableValueGraph<N, V> extends ValueGraph<N, V> {
    *     #allowsSelfLoops()}
    */
   @CanIgnoreReturnValue
+  @CheckForNull
   V putEdgeValue(N nodeU, N nodeV, V value);
 
   /**
@@ -83,6 +86,7 @@ public interface MutableValueGraph<N, V> extends ValueGraph<N, V> {
    * @since 27.1
    */
   @CanIgnoreReturnValue
+  @CheckForNull
   V putEdgeValue(EndpointPair<N> endpoints, V value);
 
   /**
@@ -100,6 +104,7 @@ public interface MutableValueGraph<N, V> extends ValueGraph<N, V> {
    *     nodeV}, or null if there was no such edge.
    */
   @CanIgnoreReturnValue
+  @CheckForNull
   V removeEdge(N nodeU, N nodeV);
 
   /**
@@ -112,5 +117,6 @@ public interface MutableValueGraph<N, V> extends ValueGraph<N, V> {
    * @since 27.1
    */
   @CanIgnoreReturnValue
+  @CheckForNull
   V removeEdge(EndpointPair<N> endpoints);
 }
diff --git a/android/guava/src/com/google/common/graph/Network.java b/android/guava/src/com/google/common/graph/Network.java
index a7c90865b1c6..70e39cdc083c 100644
--- a/android/guava/src/com/google/common/graph/Network.java
+++ b/android/guava/src/com/google/common/graph/Network.java
@@ -19,7 +19,7 @@
 import com.google.common.annotations.Beta;
 import com.google.errorprone.annotations.DoNotMock;
 import java.util.Set;
-import org.checkerframework.checker.nullness.compatqual.NullableDecl;
+import javax.annotation.CheckForNull;
 
 /**
  * An interface for <a
@@ -103,6 +103,7 @@
  */
 @Beta
 @DoNotMock("Use NetworkBuilder to create a real instance")
+@ElementTypesAreNonnullByDefault
 public interface Network<N, E> extends SuccessorsFunction<N>, PredecessorsFunction<N> {
   //
   // Network-level accessors
@@ -318,7 +319,7 @@ public interface Network<N, E> extends SuccessorsFunction<N>, PredecessorsFuncti
    *     network
    * @since 23.0
    */
-  @NullableDecl
+  @CheckForNull
   E edgeConnectingOrNull(N nodeU, N nodeV);
 
   /**
@@ -333,7 +334,7 @@ public interface Network<N, E> extends SuccessorsFunction<N>, PredecessorsFuncti
    * @throws IllegalArgumentException if the endpoints are unordered and the graph is directed
    * @since 27.1
    */
-  @NullableDecl
+  @CheckForNull
   E edgeConnectingOrNull(EndpointPair<N> endpoints);
 
   /**
@@ -385,7 +386,7 @@ public interface Network<N, E> extends SuccessorsFunction<N>, PredecessorsFuncti
    * <p>A reference implementation of this is provided by {@link AbstractNetwork#equals(Object)}.
    */
   @Override
-  boolean equals(@NullableDecl Object object);
+  boolean equals(@CheckForNull Object object);
 
   /**
    * Returns the hash code for this network. The hash code of a network is defined as the hash code
diff --git a/android/guava/src/com/google/common/graph/NetworkBuilder.java b/android/guava/src/com/google/common/graph/NetworkBuilder.java
index d289ee2d53d6..968944493c7b 100644
--- a/android/guava/src/com/google/common/graph/NetworkBuilder.java
+++ b/android/guava/src/com/google/common/graph/NetworkBuilder.java
@@ -67,6 +67,7 @@
  * @since 20.0
  */
 @Beta
+@ElementTypesAreNonnullByDefault
 public final class NetworkBuilder<N, E> extends AbstractGraphBuilder<N> {
   boolean allowsParallelEdges = false;
   ElementOrder<? super E> edgeOrder = ElementOrder.insertion();
diff --git a/android/guava/src/com/google/common/graph/NetworkConnections.java b/android/guava/src/com/google/common/graph/NetworkConnections.java
index 16a68d6cb830..94d1780d3135 100644
--- a/android/guava/src/com/google/common/graph/NetworkConnections.java
+++ b/android/guava/src/com/google/common/graph/NetworkConnections.java
@@ -18,6 +18,7 @@
 
 import com.google.errorprone.annotations.CanIgnoreReturnValue;
 import java.util.Set;
+import javax.annotation.CheckForNull;
 
 /**
  * An interface for representing and manipulating an origin node's adjacent nodes and incident edges
@@ -27,6 +28,7 @@
  * @param <N> Node parameter type
  * @param <E> Edge parameter type
  */
+@ElementTypesAreNonnullByDefault
 interface NetworkConnections<N, E> {
 
   Set<N> adjacentNodes();
@@ -60,6 +62,7 @@ interface NetworkConnections<N, E> {
    * <p>In the undirected case, returns {@code null} if {@code isSelfLoop} is true.
    */
   @CanIgnoreReturnValue
+  @CheckForNull
   N removeInEdge(E edge, boolean isSelfLoop);
 
   /** Remove {@code edge} from the set of outgoing edges. Returns the former successor node. */
diff --git a/android/guava/src/com/google/common/graph/ParametricNullness.java b/android/guava/src/com/google/common/graph/ParametricNullness.java
new file mode 100644
index 000000000000..87ff930a4aac
--- /dev/null
+++ b/android/guava/src/com/google/common/graph/ParametricNullness.java
@@ -0,0 +1,52 @@
+/*
+ * Copyright (C) 2021 The Guava Authors
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package com.google.common.graph;
+
+import static java.lang.annotation.ElementType.FIELD;
+import static java.lang.annotation.ElementType.METHOD;
+import static java.lang.annotation.ElementType.PARAMETER;
+import static java.lang.annotation.RetentionPolicy.RUNTIME;
+
+import com.google.common.annotations.GwtCompatible;
+import java.lang.annotation.Retention;
+import java.lang.annotation.Target;
+
+/**
+ * Marks a "top-level" type-variable usage as the closest we can get to "non-nullable when
+ * non-nullable; nullable when nullable" (like the Android <a
+ * href="https://android.googlesource.com/platform/libcore/+/master/luni/src/main/java/libcore/util/NullFromTypeParam.java">{@code
+ * NullFromTypeParam}</a>).
+ *
+ * <p>Consumers of this annotation include:
+ *
+ * <ul>
+ *   <li>Kotlin, for which it makes the type-variable usage (a) a Kotlin platform type when the type
+ *       argument is non-nullable and (b) nullable when the type argument is nullable. We use this
+ *       to "undo" {@link ElementTypesAreNonnullByDefault}.
+ *   <li><a href="https://developers.google.com/j2objc">J2ObjC</a>
+ *   <li>{@code NullPointerTester}, at least in the Android backport (where the type-use annotations
+ *       {@code NullPointerTester} would need are not available) and in case of <a
+ *       href="https://bugs.openjdk.java.net/browse/JDK-8202469">JDK-8202469</a>
+ * </ul>
+ *
+ */
+@GwtCompatible
+@Retention(RUNTIME)
+@Target({FIELD, METHOD, PARAMETER})
+@javax.annotation.meta.TypeQualifierNickname
+@javax.annotation.Nonnull(when = javax.annotation.meta.When.UNKNOWN)
+@interface ParametricNullness {}
diff --git a/android/guava/src/com/google/common/graph/PredecessorsFunction.java b/android/guava/src/com/google/common/graph/PredecessorsFunction.java
index f9ca48ae77b9..750a8acd603b 100644
--- a/android/guava/src/com/google/common/graph/PredecessorsFunction.java
+++ b/android/guava/src/com/google/common/graph/PredecessorsFunction.java
@@ -80,6 +80,7 @@
  */
 @Beta
 @DoNotMock("Implement with a lambda, or use GraphBuilder to build a Graph with the desired edges")
+@ElementTypesAreNonnullByDefault
 public interface PredecessorsFunction<N> {
 
   /**
diff --git a/android/guava/src/com/google/common/graph/StandardMutableGraph.java b/android/guava/src/com/google/common/graph/StandardMutableGraph.java
index 41acccff5963..1be9640f419e 100644
--- a/android/guava/src/com/google/common/graph/StandardMutableGraph.java
+++ b/android/guava/src/com/google/common/graph/StandardMutableGraph.java
@@ -28,6 +28,7 @@
  * @author James Sexton
  * @param <N> Node parameter type
  */
+@ElementTypesAreNonnullByDefault
 final class StandardMutableGraph<N> extends ForwardingGraph<N> implements MutableGraph<N> {
   private final MutableValueGraph<N, Presence> backingValueGraph;
 
@@ -37,7 +38,7 @@ final class StandardMutableGraph<N> extends ForwardingGraph<N> implements Mutabl
   }
 
   @Override
-  protected BaseGraph<N> delegate() {
+  BaseGraph<N> delegate() {
     return backingValueGraph;
   }
 
diff --git a/android/guava/src/com/google/common/graph/StandardMutableNetwork.java b/android/guava/src/com/google/common/graph/StandardMutableNetwork.java
index 8cfe9c526021..c58b6d39093e 100644
--- a/android/guava/src/com/google/common/graph/StandardMutableNetwork.java
+++ b/android/guava/src/com/google/common/graph/StandardMutableNetwork.java
@@ -22,6 +22,7 @@
 import static com.google.common.graph.GraphConstants.PARALLEL_EDGES_NOT_ALLOWED;
 import static com.google.common.graph.GraphConstants.REUSING_EDGE;
 import static com.google.common.graph.GraphConstants.SELF_LOOPS_NOT_ALLOWED;
+import static java.util.Objects.requireNonNull;
 
 import com.google.common.collect.ImmutableList;
 import com.google.errorprone.annotations.CanIgnoreReturnValue;
@@ -39,6 +40,7 @@
  * @param <N> Node parameter type
  * @param <E> Edge parameter type
  */
+@ElementTypesAreNonnullByDefault
 final class StandardMutableNetwork<N, E> extends StandardNetwork<N, E>
     implements MutableNetwork<N, E> {
 
@@ -152,9 +154,10 @@ public boolean removeEdge(E edge) {
       return false;
     }
 
-    NetworkConnections<N, E> connectionsU = nodeConnections.get(nodeU);
+    // requireNonNull is safe because of the edgeToReferenceNode check above.
+    NetworkConnections<N, E> connectionsU = requireNonNull(nodeConnections.get(nodeU));
     N nodeV = connectionsU.adjacentNode(edge);
-    NetworkConnections<N, E> connectionsV = nodeConnections.get(nodeV);
+    NetworkConnections<N, E> connectionsV = requireNonNull(nodeConnections.get(nodeV));
     connectionsU.removeOutEdge(edge);
     connectionsV.removeInEdge(edge, allowsSelfLoops() && nodeU.equals(nodeV));
     edgeToReferenceNode.remove(edge);
diff --git a/android/guava/src/com/google/common/graph/StandardMutableValueGraph.java b/android/guava/src/com/google/common/graph/StandardMutableValueGraph.java
index 558d8d60976e..0ea641a5b1cd 100644
--- a/android/guava/src/com/google/common/graph/StandardMutableValueGraph.java
+++ b/android/guava/src/com/google/common/graph/StandardMutableValueGraph.java
@@ -22,8 +22,10 @@
 import static com.google.common.graph.GraphConstants.SELF_LOOPS_NOT_ALLOWED;
 import static com.google.common.graph.Graphs.checkNonNegative;
 import static com.google.common.graph.Graphs.checkPositive;
+import static java.util.Objects.requireNonNull;
 
 import com.google.errorprone.annotations.CanIgnoreReturnValue;
+import javax.annotation.CheckForNull;
 
 /**
  * Standard implementation of {@link MutableValueGraph} that supports both directed and undirected
@@ -38,6 +40,7 @@
  * @param <N> Node parameter type
  * @param <V> Value parameter type
  */
+@ElementTypesAreNonnullByDefault
 final class StandardMutableValueGraph<N, V> extends StandardValueGraph<N, V>
     implements MutableValueGraph<N, V> {
 
@@ -81,6 +84,7 @@ private GraphConnections<N, V> addNodeInternal(N node) {
 
   @Override
   @CanIgnoreReturnValue
+  @CheckForNull
   public V putEdgeValue(N nodeU, N nodeV, V value) {
     checkNotNull(nodeU, "nodeU");
     checkNotNull(nodeV, "nodeV");
@@ -108,6 +112,7 @@ public V putEdgeValue(N nodeU, N nodeV, V value) {
 
   @Override
   @CanIgnoreReturnValue
+  @CheckForNull
   public V putEdgeValue(EndpointPair<N> endpoints, V value) {
     validateEndpoints(endpoints);
     return putEdgeValue(endpoints.nodeU(), endpoints.nodeV(), value);
@@ -132,12 +137,16 @@ public boolean removeNode(N node) {
     }
 
     for (N successor : connections.successors()) {
-      nodeConnections.getWithoutCaching(successor).removePredecessor(node);
+      // requireNonNull is safe because the node is a successor.
+      requireNonNull(nodeConnections.getWithoutCaching(successor)).removePredecessor(node);
       --edgeCount;
     }
     if (isDirected()) { // In undirected graphs, the successor and predecessor sets are equal.
       for (N predecessor : connections.predecessors()) {
-        checkState(nodeConnections.getWithoutCaching(predecessor).removeSuccessor(node) != null);
+        // requireNonNull is safe because the node is a predecessor.
+        checkState(
+            requireNonNull(nodeConnections.getWithoutCaching(predecessor)).removeSuccessor(node)
+                != null);
         --edgeCount;
       }
     }
@@ -148,6 +157,7 @@ public boolean removeNode(N node) {
 
   @Override
   @CanIgnoreReturnValue
+  @CheckForNull
   public V removeEdge(N nodeU, N nodeV) {
     checkNotNull(nodeU, "nodeU");
     checkNotNull(nodeV, "nodeV");
@@ -168,6 +178,7 @@ public V removeEdge(N nodeU, N nodeV) {
 
   @Override
   @CanIgnoreReturnValue
+  @CheckForNull
   public V removeEdge(EndpointPair<N> endpoints) {
     validateEndpoints(endpoints);
     return removeEdge(endpoints.nodeU(), endpoints.nodeV());
diff --git a/android/guava/src/com/google/common/graph/StandardNetwork.java b/android/guava/src/com/google/common/graph/StandardNetwork.java
index 0fc292bfab56..2aa103f99683 100644
--- a/android/guava/src/com/google/common/graph/StandardNetwork.java
+++ b/android/guava/src/com/google/common/graph/StandardNetwork.java
@@ -22,12 +22,12 @@
 import static com.google.common.graph.GraphConstants.DEFAULT_NODE_COUNT;
 import static com.google.common.graph.GraphConstants.EDGE_NOT_IN_GRAPH;
 import static com.google.common.graph.GraphConstants.NODE_NOT_IN_GRAPH;
+import static java.util.Objects.requireNonNull;
 
 import com.google.common.collect.ImmutableSet;
 import java.util.Map;
 import java.util.Set;
 import java.util.TreeMap;
-import org.checkerframework.checker.nullness.compatqual.NullableDecl;
 
 /**
  * Standard implementation of {@link Network} that supports the options supplied by {@link
@@ -48,6 +48,7 @@
  * @param <N> Node parameter type
  * @param <E> Edge parameter type
  */
+@ElementTypesAreNonnullByDefault
 class StandardNetwork<N, E> extends AbstractNetwork<N, E> {
   private final boolean isDirected;
   private final boolean allowsParallelEdges;
@@ -55,11 +56,11 @@ class StandardNetwork<N, E> extends AbstractNetwork<N, E> {
   private final ElementOrder<N> nodeOrder;
   private final ElementOrder<E> edgeOrder;
 
-  protected final MapIteratorCache<N, NetworkConnections<N, E>> nodeConnections;
+  final MapIteratorCache<N, NetworkConnections<N, E>> nodeConnections;
 
   // We could make this a Map<E, EndpointPair<N>>. It would make incidentNodes(edge) slightly
   // faster, but also make Networks consume 5 to 20+% (increasing with average degree) more memory.
-  protected final MapIteratorCache<E, N> edgeToReferenceNode; // referenceNode == source if directed
+  final MapIteratorCache<E, N> edgeToReferenceNode; // referenceNode == source if directed
 
   /** Constructs a graph with the properties specified in {@code builder}. */
   StandardNetwork(NetworkBuilder<? super N, ? super E> builder) {
@@ -135,7 +136,8 @@ public Set<E> incidentEdges(N node) {
   @Override
   public EndpointPair<N> incidentNodes(E edge) {
     N nodeU = checkedReferenceNode(edge);
-    N nodeV = nodeConnections.get(nodeU).adjacentNode(edge);
+    // requireNonNull is safe because checkedReferenceNode made sure the edge is in the network.
+    N nodeV = requireNonNull(nodeConnections.get(nodeU)).adjacentNode(edge);
     return EndpointPair.of(this, nodeU, nodeV);
   }
 
@@ -174,7 +176,7 @@ public Set<N> successors(N node) {
     return checkedConnections(node).successors();
   }
 
-  protected final NetworkConnections<N, E> checkedConnections(N node) {
+  final NetworkConnections<N, E> checkedConnections(N node) {
     NetworkConnections<N, E> connections = nodeConnections.get(node);
     if (connections == null) {
       checkNotNull(node);
@@ -183,7 +185,7 @@ protected final NetworkConnections<N, E> checkedConnections(N node) {
     return connections;
   }
 
-  protected final N checkedReferenceNode(E edge) {
+  final N checkedReferenceNode(E edge) {
     N referenceNode = edgeToReferenceNode.get(edge);
     if (referenceNode == null) {
       checkNotNull(edge);
@@ -192,11 +194,11 @@ protected final N checkedReferenceNode(E edge) {
     return referenceNode;
   }
 
-  protected final boolean containsNode(@NullableDecl N node) {
+  final boolean containsNode(N node) {
     return nodeConnections.containsKey(node);
   }
 
-  protected final boolean containsEdge(@NullableDecl E edge) {
+  final boolean containsEdge(E edge) {
     return edgeToReferenceNode.containsKey(edge);
   }
 }
diff --git a/android/guava/src/com/google/common/graph/StandardValueGraph.java b/android/guava/src/com/google/common/graph/StandardValueGraph.java
index 4eed0bee4460..ab3ae582b55e 100644
--- a/android/guava/src/com/google/common/graph/StandardValueGraph.java
+++ b/android/guava/src/com/google/common/graph/StandardValueGraph.java
@@ -24,7 +24,7 @@
 import java.util.Map;
 import java.util.Set;
 import java.util.TreeMap;
-import org.checkerframework.checker.nullness.compatqual.NullableDecl;
+import javax.annotation.CheckForNull;
 
 /**
  * Standard implementation of {@link ValueGraph} that supports the options supplied by {@link
@@ -43,14 +43,15 @@
  * @param <N> Node parameter type
  * @param <V> Value parameter type
  */
+@ElementTypesAreNonnullByDefault
 class StandardValueGraph<N, V> extends AbstractValueGraph<N, V> {
   private final boolean isDirected;
   private final boolean allowsSelfLoops;
   private final ElementOrder<N> nodeOrder;
 
-  protected final MapIteratorCache<N, GraphConnections<N, V>> nodeConnections;
+  final MapIteratorCache<N, GraphConnections<N, V>> nodeConnections;
 
-  protected long edgeCount; // must be updated when edges are added or removed
+  long edgeCount; // must be updated when edges are added or removed
 
   /** Constructs a graph with the properties specified in {@code builder}. */
   StandardValueGraph(AbstractGraphBuilder<? super N> builder) {
@@ -117,7 +118,7 @@ public Set<N> successors(N node) {
 
   @Override
   public Set<EndpointPair<N>> incidentEdges(N node) {
-    final GraphConnections<N, V> connections = checkedConnections(node);
+    GraphConnections<N, V> connections = checkedConnections(node);
 
     return new IncidentEdgeSet<N>(this, node) {
       @Override
@@ -129,27 +130,27 @@ public Iterator<EndpointPair<N>> iterator() {
 
   @Override
   public boolean hasEdgeConnecting(N nodeU, N nodeV) {
-    return hasEdgeConnecting_internal(checkNotNull(nodeU), checkNotNull(nodeV));
+    return hasEdgeConnectingInternal(checkNotNull(nodeU), checkNotNull(nodeV));
   }
 
   @Override
   public boolean hasEdgeConnecting(EndpointPair<N> endpoints) {
     checkNotNull(endpoints);
     return isOrderingCompatible(endpoints)
-        && hasEdgeConnecting_internal(endpoints.nodeU(), endpoints.nodeV());
+        && hasEdgeConnectingInternal(endpoints.nodeU(), endpoints.nodeV());
   }
 
   @Override
-  @NullableDecl
-  public V edgeValueOrDefault(N nodeU, N nodeV, @NullableDecl V defaultValue) {
-    return edgeValueOrDefault_internal(checkNotNull(nodeU), checkNotNull(nodeV), defaultValue);
+  @CheckForNull
+  public V edgeValueOrDefault(N nodeU, N nodeV, @CheckForNull V defaultValue) {
+    return edgeValueOrDefaultInternal(checkNotNull(nodeU), checkNotNull(nodeV), defaultValue);
   }
 
   @Override
-  @NullableDecl
-  public V edgeValueOrDefault(EndpointPair<N> endpoints, @NullableDecl V defaultValue) {
+  @CheckForNull
+  public V edgeValueOrDefault(EndpointPair<N> endpoints, @CheckForNull V defaultValue) {
     validateEndpoints(endpoints);
-    return edgeValueOrDefault_internal(endpoints.nodeU(), endpoints.nodeV(), defaultValue);
+    return edgeValueOrDefaultInternal(endpoints.nodeU(), endpoints.nodeV(), defaultValue);
   }
 
   @Override
@@ -157,7 +158,7 @@ protected long edgeCount() {
     return edgeCount;
   }
 
-  protected final GraphConnections<N, V> checkedConnections(N node) {
+  private final GraphConnections<N, V> checkedConnections(N node) {
     GraphConnections<N, V> connections = nodeConnections.get(node);
     if (connections == null) {
       checkNotNull(node);
@@ -166,18 +167,24 @@ protected final GraphConnections<N, V> checkedConnections(N node) {
     return connections;
   }
 
-  protected final boolean containsNode(@NullableDecl N node) {
+  final boolean containsNode(@CheckForNull N node) {
     return nodeConnections.containsKey(node);
   }
 
-  protected final boolean hasEdgeConnecting_internal(N nodeU, N nodeV) {
+  private final boolean hasEdgeConnectingInternal(N nodeU, N nodeV) {
     GraphConnections<N, V> connectionsU = nodeConnections.get(nodeU);
     return (connectionsU != null) && connectionsU.successors().contains(nodeV);
   }
 
-  protected final V edgeValueOrDefault_internal(N nodeU, N nodeV, V defaultValue) {
+  @CheckForNull
+  private final V edgeValueOrDefaultInternal(N nodeU, N nodeV, @CheckForNull V defaultValue) {
     GraphConnections<N, V> connectionsU = nodeConnections.get(nodeU);
     V value = (connectionsU == null) ? null : connectionsU.value(nodeV);
-    return value == null ? defaultValue : value;
+    // TODO(b/192579700): Use a ternary once it no longer confuses our nullness checker.
+    if (value == null) {
+      return defaultValue;
+    } else {
+      return value;
+    }
   }
 }
diff --git a/android/guava/src/com/google/common/graph/SuccessorsFunction.java b/android/guava/src/com/google/common/graph/SuccessorsFunction.java
index f74f437c2937..c29bb4b94360 100644
--- a/android/guava/src/com/google/common/graph/SuccessorsFunction.java
+++ b/android/guava/src/com/google/common/graph/SuccessorsFunction.java
@@ -80,6 +80,7 @@
  */
 @Beta
 @DoNotMock("Implement with a lambda, or use GraphBuilder to build a Graph with the desired edges")
+@ElementTypesAreNonnullByDefault
 public interface SuccessorsFunction<N> {
 
   /**
diff --git a/android/guava/src/com/google/common/graph/Traverser.java b/android/guava/src/com/google/common/graph/Traverser.java
index 0d8e6f97fa32..fb594b440365 100644
--- a/android/guava/src/com/google/common/graph/Traverser.java
+++ b/android/guava/src/com/google/common/graph/Traverser.java
@@ -18,6 +18,7 @@
 
 import static com.google.common.base.Preconditions.checkArgument;
 import static com.google.common.base.Preconditions.checkNotNull;
+import static java.util.Objects.requireNonNull;
 
 import com.google.common.annotations.Beta;
 import com.google.common.collect.AbstractIterator;
@@ -28,7 +29,7 @@
 import java.util.HashSet;
 import java.util.Iterator;
 import java.util.Set;
-import org.checkerframework.checker.nullness.compatqual.NullableDecl;
+import javax.annotation.CheckForNull;
 
 /**
  * An object that can traverse the nodes that are reachable from a specified (set of) start node(s)
@@ -63,6 +64,7 @@
 @DoNotMock(
     "Call forGraph or forTree, passing a lambda or a Graph with the desired edges (built with"
         + " GraphBuilder)")
+@ElementTypesAreNonnullByDefault
 public abstract class Traverser<N> {
   private final SuccessorsFunction<N> successorFunction;
 
@@ -94,7 +96,7 @@ private Traverser(SuccessorsFunction<N> successorFunction) {
    *
    * @param graph {@link SuccessorsFunction} representing a general graph that may have cycles.
    */
-  public static <N> Traverser<N> forGraph(final SuccessorsFunction<N> graph) {
+  public static <N> Traverser<N> forGraph(SuccessorsFunction<N> graph) {
     return new Traverser<N>(graph) {
       @Override
       Traversal<N> newTraversal() {
@@ -176,7 +178,7 @@ Traversal<N> newTraversal() {
    * @param tree {@link SuccessorsFunction} representing a directed acyclic graph that has at most
    *     one path between any two nodes
    */
-  public static <N> Traverser<N> forTree(final SuccessorsFunction<N> tree) {
+  public static <N> Traverser<N> forTree(SuccessorsFunction<N> tree) {
     if (tree instanceof BaseGraph) {
       checkArgument(((BaseGraph<?>) tree).isDirected(), "Undirected graphs can never be trees.");
     }
@@ -237,7 +239,7 @@ public final Iterable<N> breadthFirst(N startNode) {
    * @since 24.1
    */
   public final Iterable<N> breadthFirst(Iterable<? extends N> startNodes) {
-    final ImmutableSet<N> validated = validate(startNodes);
+    ImmutableSet<N> validated = validate(startNodes);
     return new Iterable<N>() {
       @Override
       public Iterator<N> iterator() {
@@ -292,7 +294,7 @@ public final Iterable<N> depthFirstPreOrder(N startNode) {
    * @since 24.1
    */
   public final Iterable<N> depthFirstPreOrder(Iterable<? extends N> startNodes) {
-    final ImmutableSet<N> validated = validate(startNodes);
+    ImmutableSet<N> validated = validate(startNodes);
     return new Iterable<N>() {
       @Override
       public Iterator<N> iterator() {
@@ -347,7 +349,7 @@ public final Iterable<N> depthFirstPostOrder(N startNode) {
    * @since 24.1
    */
   public final Iterable<N> depthFirstPostOrder(Iterable<? extends N> startNodes) {
-    final ImmutableSet<N> validated = validate(startNodes);
+    ImmutableSet<N> validated = validate(startNodes);
     return new Iterable<N>() {
       @Override
       public Iterator<N> iterator() {
@@ -380,13 +382,23 @@ private abstract static class Traversal<N> {
     }
 
     static <N> Traversal<N> inGraph(SuccessorsFunction<N> graph) {
-      final Set<N> visited = new HashSet<>();
+      Set<N> visited = new HashSet<>();
       return new Traversal<N>(graph) {
         @Override
+        @CheckForNull
         N visitNext(Deque<Iterator<? extends N>> horizon) {
           Iterator<? extends N> top = horizon.getFirst();
           while (top.hasNext()) {
-            N element = checkNotNull(top.next());
+            N element = top.next();
+            // requireNonNull is safe because horizon contains only graph nodes.
+            /*
+             * TODO(cpovirk): Replace these two statements with one (`N element =
+             * requireNonNull(top.next())`) once our checker supports it.
+             *
+             * (The problem is likely
+             * https://github.com/jspecify/nullness-checker-for-checker-framework/blob/61aafa4ae52594830cfc2d61c8b113009dbdb045/src/main/java/com/google/jspecify/nullness/NullSpecAnnotatedTypeFactory.java#L896)
+             */
+            requireNonNull(element);
             if (visited.add(element)) {
               return element;
             }
@@ -399,6 +411,7 @@ N visitNext(Deque<Iterator<? extends N>> horizon) {
 
     static <N> Traversal<N> inTree(SuccessorsFunction<N> tree) {
       return new Traversal<N>(tree) {
+        @CheckForNull
         @Override
         N visitNext(Deque<Iterator<? extends N>> horizon) {
           Iterator<? extends N> top = horizon.getFirst();
@@ -425,11 +438,12 @@ final Iterator<N> preOrder(Iterator<? extends N> startNodes) {
      * determined by the {@code InsertionOrder} parameter: nieces are placed at the FRONT before
      * aunts for pre-order; while in BFS they are placed at the BACK after aunts.
      */
-    private Iterator<N> topDown(Iterator<? extends N> startNodes, final InsertionOrder order) {
-      final Deque<Iterator<? extends N>> horizon = new ArrayDeque<>();
+    private Iterator<N> topDown(Iterator<? extends N> startNodes, InsertionOrder order) {
+      Deque<Iterator<? extends N>> horizon = new ArrayDeque<>();
       horizon.add(startNodes);
       return new AbstractIterator<N>() {
         @Override
+        @CheckForNull
         protected N computeNext() {
           do {
             N next = visitNext(horizon);
@@ -449,11 +463,12 @@ protected N computeNext() {
     }
 
     final Iterator<N> postOrder(Iterator<? extends N> startNodes) {
-      final Deque<N> ancestorStack = new ArrayDeque<>();
-      final Deque<Iterator<? extends N>> horizon = new ArrayDeque<>();
+      Deque<N> ancestorStack = new ArrayDeque<>();
+      Deque<Iterator<? extends N>> horizon = new ArrayDeque<>();
       horizon.add(startNodes);
       return new AbstractIterator<N>() {
         @Override
+        @CheckForNull
         protected N computeNext() {
           for (N next = visitNext(horizon); next != null; next = visitNext(horizon)) {
             Iterator<? extends N> successors = successorFunction.successors(next).iterator();
@@ -463,7 +478,11 @@ protected N computeNext() {
             horizon.addFirst(successors);
             ancestorStack.push(next);
           }
-          return ancestorStack.isEmpty() ? endOfData() : ancestorStack.pop();
+          // TODO(b/192579700): Use a ternary once it no longer confuses our nullness checker.
+          if (!ancestorStack.isEmpty()) {
+            return ancestorStack.pop();
+          }
+          return endOfData();
         }
       };
     }
@@ -478,7 +497,7 @@ protected N computeNext() {
      * into {@code horizon} between calls to {@code visitNext()}. This causes them to receive
      * additional values interleaved with those shown above.)
      */
-    @NullableDecl
+    @CheckForNull
     abstract N visitNext(Deque<Iterator<? extends N>> horizon);
   }
 
diff --git a/android/guava/src/com/google/common/graph/UndirectedGraphConnections.java b/android/guava/src/com/google/common/graph/UndirectedGraphConnections.java
index 49689f9d8aec..4eeb2328fe0e 100644
--- a/android/guava/src/com/google/common/graph/UndirectedGraphConnections.java
+++ b/android/guava/src/com/google/common/graph/UndirectedGraphConnections.java
@@ -20,7 +20,6 @@
 import static com.google.common.graph.GraphConstants.INNER_CAPACITY;
 import static com.google.common.graph.GraphConstants.INNER_LOAD_FACTOR;
 
-import com.google.common.base.Function;
 import com.google.common.collect.ImmutableMap;
 import com.google.common.collect.Iterators;
 import java.util.Collections;
@@ -29,6 +28,7 @@
 import java.util.LinkedHashMap;
 import java.util.Map;
 import java.util.Set;
+import javax.annotation.CheckForNull;
 
 /**
  * An implementation of {@link GraphConnections} for undirected graphs.
@@ -37,6 +37,7 @@
  * @param <N> Node parameter type
  * @param <V> Value parameter type
  */
+@ElementTypesAreNonnullByDefault
 final class UndirectedGraphConnections<N, V> implements GraphConnections<N, V> {
   private final Map<N, V> adjacentNodeValues;
 
@@ -77,18 +78,14 @@ public Set<N> successors() {
   }
 
   @Override
-  public Iterator<EndpointPair<N>> incidentEdgeIterator(final N thisNode) {
+  public Iterator<EndpointPair<N>> incidentEdgeIterator(N thisNode) {
     return Iterators.transform(
         adjacentNodeValues.keySet().iterator(),
-        new Function<N, EndpointPair<N>>() {
-          @Override
-          public EndpointPair<N> apply(N incidentNode) {
-            return EndpointPair.unordered(thisNode, incidentNode);
-          }
-        });
+        (N incidentNode) -> EndpointPair.unordered(thisNode, incidentNode));
   }
 
   @Override
+  @CheckForNull
   public V value(N node) {
     return adjacentNodeValues.get(node);
   }
@@ -100,6 +97,7 @@ public void removePredecessor(N node) {
   }
 
   @Override
+  @CheckForNull
   public V removeSuccessor(N node) {
     return adjacentNodeValues.remove(node);
   }
@@ -111,6 +109,7 @@ public void addPredecessor(N node, V value) {
   }
 
   @Override
+  @CheckForNull
   public V addSuccessor(N node, V value) {
     return adjacentNodeValues.put(node, value);
   }
diff --git a/android/guava/src/com/google/common/graph/UndirectedMultiNetworkConnections.java b/android/guava/src/com/google/common/graph/UndirectedMultiNetworkConnections.java
index a3913799a11d..6caac3b715dd 100644
--- a/android/guava/src/com/google/common/graph/UndirectedMultiNetworkConnections.java
+++ b/android/guava/src/com/google/common/graph/UndirectedMultiNetworkConnections.java
@@ -30,7 +30,7 @@
 import java.util.HashMap;
 import java.util.Map;
 import java.util.Set;
-import org.checkerframework.checker.nullness.compatqual.NullableDecl;
+import javax.annotation.CheckForNull;
 
 /**
  * An implementation of {@link NetworkConnections} for undirected networks with parallel edges.
@@ -39,6 +39,7 @@
  * @param <N> Node parameter type
  * @param <E> Edge parameter type
  */
+@ElementTypesAreNonnullByDefault
 final class UndirectedMultiNetworkConnections<N, E>
     extends AbstractUndirectedNetworkConnections<N, E> {
 
@@ -55,7 +56,7 @@ static <N, E> UndirectedMultiNetworkConnections<N, E> ofImmutable(Map<E, N> inci
     return new UndirectedMultiNetworkConnections<>(ImmutableMap.copyOf(incidentEdges));
   }
 
-  @LazyInit private transient Reference<Multiset<N>> adjacentNodesReference;
+  @CheckForNull @LazyInit private transient Reference<Multiset<N>> adjacentNodesReference;
 
   @Override
   public Set<N> adjacentNodes() {
@@ -72,7 +73,7 @@ private Multiset<N> adjacentNodesMultiset() {
   }
 
   @Override
-  public Set<E> edgesConnecting(final N node) {
+  public Set<E> edgesConnecting(N node) {
     return new MultiEdgesConnecting<E>(incidentEdgeMap, node) {
       @Override
       public int size() {
@@ -82,6 +83,7 @@ public int size() {
   }
 
   @Override
+  @CheckForNull
   public N removeInEdge(E edge, boolean isSelfLoop) {
     if (!isSelfLoop) {
       return removeOutEdge(edge);
@@ -115,8 +117,8 @@ public void addOutEdge(E edge, N node) {
     }
   }
 
-  @NullableDecl
-  private static <T> T getReference(@NullableDecl Reference<T> reference) {
+  @CheckForNull
+  private static <T> T getReference(@CheckForNull Reference<T> reference) {
     return (reference == null) ? null : reference.get();
   }
 }
diff --git a/android/guava/src/com/google/common/graph/UndirectedNetworkConnections.java b/android/guava/src/com/google/common/graph/UndirectedNetworkConnections.java
index 1e253dd05703..190897f8825d 100644
--- a/android/guava/src/com/google/common/graph/UndirectedNetworkConnections.java
+++ b/android/guava/src/com/google/common/graph/UndirectedNetworkConnections.java
@@ -32,9 +32,10 @@
  * @param <N> Node parameter type
  * @param <E> Edge parameter type
  */
+@ElementTypesAreNonnullByDefault
 final class UndirectedNetworkConnections<N, E> extends AbstractUndirectedNetworkConnections<N, E> {
 
-  protected UndirectedNetworkConnections(Map<E, N> incidentEdgeMap) {
+  UndirectedNetworkConnections(Map<E, N> incidentEdgeMap) {
     super(incidentEdgeMap);
   }
 
@@ -53,6 +54,6 @@ public Set<N> adjacentNodes() {
 
   @Override
   public Set<E> edgesConnecting(N node) {
-    return new EdgesConnecting<E>(((BiMap<E, N>) incidentEdgeMap).inverse(), node);
+    return new EdgesConnecting<>(((BiMap<E, N>) incidentEdgeMap).inverse(), node);
   }
 }
diff --git a/android/guava/src/com/google/common/graph/ValueGraph.java b/android/guava/src/com/google/common/graph/ValueGraph.java
index b7dd61c92b83..bd3cf36401e3 100644
--- a/android/guava/src/com/google/common/graph/ValueGraph.java
+++ b/android/guava/src/com/google/common/graph/ValueGraph.java
@@ -19,7 +19,7 @@
 import com.google.common.annotations.Beta;
 import java.util.Collection;
 import java.util.Set;
-import org.checkerframework.checker.nullness.compatqual.NullableDecl;
+import javax.annotation.CheckForNull;
 
 /**
  * An interface for <a
@@ -107,6 +107,7 @@
  * @since 20.0
  */
 @Beta
+@ElementTypesAreNonnullByDefault
 public interface ValueGraph<N, V> extends BaseGraph<N> {
   //
   // ValueGraph-level accessors
@@ -285,8 +286,8 @@ public interface ValueGraph<N, V> extends BaseGraph<N> {
    * @throws IllegalArgumentException if {@code nodeU} or {@code nodeV} is not an element of this
    *     graph
    */
-  @NullableDecl
-  V edgeValueOrDefault(N nodeU, N nodeV, @NullableDecl V defaultValue);
+  @CheckForNull
+  V edgeValueOrDefault(N nodeU, N nodeV, @CheckForNull V defaultValue);
 
   /**
    * Returns the value of the edge that connects {@code endpoints} (in the order, if any, specified
@@ -298,8 +299,8 @@ public interface ValueGraph<N, V> extends BaseGraph<N> {
    * @throws IllegalArgumentException if the endpoints are unordered and the graph is directed
    * @since 27.1
    */
-  @NullableDecl
-  V edgeValueOrDefault(EndpointPair<N> endpoints, @NullableDecl V defaultValue);
+  @CheckForNull
+  V edgeValueOrDefault(EndpointPair<N> endpoints, @CheckForNull V defaultValue);
 
   //
   // ValueGraph identity
@@ -326,7 +327,7 @@ public interface ValueGraph<N, V> extends BaseGraph<N> {
    * <p>A reference implementation of this is provided by {@link AbstractValueGraph#equals(Object)}.
    */
   @Override
-  boolean equals(@NullableDecl Object object);
+  boolean equals(@CheckForNull Object object);
 
   /**
    * Returns the hash code for this graph. The hash code of a graph is defined as the hash code of a
diff --git a/android/guava/src/com/google/common/graph/ValueGraphBuilder.java b/android/guava/src/com/google/common/graph/ValueGraphBuilder.java
index 4fc752da1f4a..ce146c325504 100644
--- a/android/guava/src/com/google/common/graph/ValueGraphBuilder.java
+++ b/android/guava/src/com/google/common/graph/ValueGraphBuilder.java
@@ -66,6 +66,7 @@
  * @since 20.0
  */
 @Beta
+@ElementTypesAreNonnullByDefault
 public final class ValueGraphBuilder<N, V> extends AbstractGraphBuilder<N> {
 
   /** Creates a new instance with the specified edge directionality. */
diff --git a/android/guava/src/com/google/common/hash/AbstractByteHasher.java b/android/guava/src/com/google/common/hash/AbstractByteHasher.java
index 48d48c489bf8..9f7e041909f5 100644
--- a/android/guava/src/com/google/common/hash/AbstractByteHasher.java
+++ b/android/guava/src/com/google/common/hash/AbstractByteHasher.java
@@ -32,6 +32,7 @@
  * @author Colin Decker
  */
 @CanIgnoreReturnValue
+@ElementTypesAreNonnullByDefault
 abstract class AbstractByteHasher extends AbstractHasher {
   private final ByteBuffer scratch = ByteBuffer.allocate(8).order(ByteOrder.LITTLE_ENDIAN);
 
diff --git a/android/guava/src/com/google/common/hash/AbstractCompositeHashFunction.java b/android/guava/src/com/google/common/hash/AbstractCompositeHashFunction.java
index 048e6c23587a..820fe963bf84 100644
--- a/android/guava/src/com/google/common/hash/AbstractCompositeHashFunction.java
+++ b/android/guava/src/com/google/common/hash/AbstractCompositeHashFunction.java
@@ -20,6 +20,7 @@
 import com.google.errorprone.annotations.Immutable;
 import java.nio.ByteBuffer;
 import java.nio.charset.Charset;
+import org.checkerframework.checker.nullness.qual.Nullable;
 
 /**
  * An abstract composition of multiple hash functions. {@linkplain #newHasher()} delegates to the
@@ -29,6 +30,7 @@
  * @author Dimitris Andreou
  */
 @Immutable
+@ElementTypesAreNonnullByDefault
 abstract class AbstractCompositeHashFunction extends AbstractHashFunction {
 
   @SuppressWarnings("Immutable") // array not modified after creation
@@ -68,7 +70,7 @@ public Hasher newHasher(int expectedInputSize) {
     return fromHashers(hashers);
   }
 
-  private Hasher fromHashers(final Hasher[] hashers) {
+  private Hasher fromHashers(Hasher[] hashers) {
     return new Hasher() {
       @Override
       public Hasher putByte(byte b) {
@@ -177,7 +179,8 @@ public Hasher putString(CharSequence chars, Charset charset) {
       }
 
       @Override
-      public <T> Hasher putObject(T instance, Funnel<? super T> funnel) {
+      public <T extends @Nullable Object> Hasher putObject(
+          @ParametricNullness T instance, Funnel<? super T> funnel) {
         for (Hasher hasher : hashers) {
           hasher.putObject(instance, funnel);
         }
diff --git a/android/guava/src/com/google/common/hash/AbstractHashFunction.java b/android/guava/src/com/google/common/hash/AbstractHashFunction.java
index 61841894aafc..73085560024f 100644
--- a/android/guava/src/com/google/common/hash/AbstractHashFunction.java
+++ b/android/guava/src/com/google/common/hash/AbstractHashFunction.java
@@ -20,6 +20,7 @@
 import com.google.errorprone.annotations.Immutable;
 import java.nio.ByteBuffer;
 import java.nio.charset.Charset;
+import org.checkerframework.checker.nullness.qual.Nullable;
 
 /**
  * Skeleton implementation of {@link HashFunction} in terms of {@link #newHasher()}.
@@ -27,9 +28,11 @@
  * <p>TODO(lowasser): make public
  */
 @Immutable
+@ElementTypesAreNonnullByDefault
 abstract class AbstractHashFunction implements HashFunction {
   @Override
-  public <T> HashCode hashObject(T instance, Funnel<? super T> funnel) {
+  public <T extends @Nullable Object> HashCode hashObject(
+      @ParametricNullness T instance, Funnel<? super T> funnel) {
     return newHasher().putObject(instance, funnel).hash();
   }
 
diff --git a/android/guava/src/com/google/common/hash/AbstractHasher.java b/android/guava/src/com/google/common/hash/AbstractHasher.java
index 326aa8df657f..c72e05be05e3 100644
--- a/android/guava/src/com/google/common/hash/AbstractHasher.java
+++ b/android/guava/src/com/google/common/hash/AbstractHasher.java
@@ -18,6 +18,7 @@
 import com.google.errorprone.annotations.CanIgnoreReturnValue;
 import java.nio.ByteBuffer;
 import java.nio.charset.Charset;
+import org.checkerframework.checker.nullness.qual.Nullable;
 
 /**
  * An abstract implementation of {@link Hasher}, which only requires subtypes to implement {@link
@@ -26,6 +27,7 @@
  * @author Dimitris Andreou
  */
 @CanIgnoreReturnValue
+@ElementTypesAreNonnullByDefault
 abstract class AbstractHasher implements Hasher {
   @Override
   public final Hasher putBoolean(boolean b) {
@@ -114,7 +116,8 @@ public Hasher putChar(char c) {
   }
 
   @Override
-  public <T> Hasher putObject(T instance, Funnel<? super T> funnel) {
+  public <T extends @Nullable Object> Hasher putObject(
+      @ParametricNullness T instance, Funnel<? super T> funnel) {
     funnel.funnel(instance, this);
     return this;
   }
diff --git a/android/guava/src/com/google/common/hash/AbstractNonStreamingHashFunction.java b/android/guava/src/com/google/common/hash/AbstractNonStreamingHashFunction.java
index 54c76de19564..4969e35b22ba 100644
--- a/android/guava/src/com/google/common/hash/AbstractNonStreamingHashFunction.java
+++ b/android/guava/src/com/google/common/hash/AbstractNonStreamingHashFunction.java
@@ -30,6 +30,7 @@
  * @author Dimitris Andreou
  */
 @Immutable
+@ElementTypesAreNonnullByDefault
 abstract class AbstractNonStreamingHashFunction extends AbstractHashFunction {
   @Override
   public Hasher newHasher() {
diff --git a/android/guava/src/com/google/common/hash/AbstractStreamingHasher.java b/android/guava/src/com/google/common/hash/AbstractStreamingHasher.java
index 67de74baf599..a987b48c35f7 100644
--- a/android/guava/src/com/google/common/hash/AbstractStreamingHasher.java
+++ b/android/guava/src/com/google/common/hash/AbstractStreamingHasher.java
@@ -29,6 +29,7 @@
  */
 // TODO(kevinb): this class still needs some design-and-document-for-inheritance love
 @CanIgnoreReturnValue
+@ElementTypesAreNonnullByDefault
 abstract class AbstractStreamingHasher extends AbstractHasher {
   /** Buffer via which we pass data to the hash algorithm (the implementor) */
   private final ByteBuffer buffer;
diff --git a/android/guava/src/com/google/common/hash/BloomFilter.java b/android/guava/src/com/google/common/hash/BloomFilter.java
index 27187f7ea219..331d160dc0ce 100644
--- a/android/guava/src/com/google/common/hash/BloomFilter.java
+++ b/android/guava/src/com/google/common/hash/BloomFilter.java
@@ -23,6 +23,7 @@
 import com.google.common.base.Predicate;
 import com.google.common.hash.BloomFilterStrategies.LockFreeBitArray;
 import com.google.common.math.DoubleMath;
+import com.google.common.math.LongMath;
 import com.google.common.primitives.SignedBytes;
 import com.google.common.primitives.UnsignedBytes;
 import com.google.errorprone.annotations.CanIgnoreReturnValue;
@@ -33,7 +34,8 @@
 import java.io.OutputStream;
 import java.io.Serializable;
 import java.math.RoundingMode;
-import org.checkerframework.checker.nullness.compatqual.NullableDecl;
+import javax.annotation.CheckForNull;
+import org.checkerframework.checker.nullness.qual.Nullable;
 
 /**
  * A Bloom filter for instances of {@code T}. A Bloom filter offers an approximate containment test
@@ -41,7 +43,7 @@
  * but if it claims that an element is <i>not</i> contained in it, then this is definitely true.
  *
  * <p>If you are unfamiliar with Bloom filters, this nice <a
- * href="http://llimllib.github.com/bloomfilter-tutorial/">tutorial</a> may help you understand how
+ * href="http://llimllib.github.io/bloomfilter-tutorial/">tutorial</a> may help you understand how
  * they work.
  *
  * <p>The false positive probability ({@code FPP}) of a Bloom filter is defined as the probability
@@ -63,7 +65,8 @@
  * @since 11.0 (thread-safe since 23.0)
  */
 @Beta
-public final class BloomFilter<T> implements Predicate<T>, Serializable {
+@ElementTypesAreNonnullByDefault
+public final class BloomFilter<T extends @Nullable Object> implements Predicate<T>, Serializable {
   /**
    * A strategy to translate T instances, to {@code numHashFunctions} bit indexes.
    *
@@ -76,15 +79,21 @@ interface Strategy extends java.io.Serializable {
      *
      * <p>Returns whether any bits changed as a result of this operation.
      */
-    <T> boolean put(
-        T object, Funnel<? super T> funnel, int numHashFunctions, LockFreeBitArray bits);
+    <T extends @Nullable Object> boolean put(
+        @ParametricNullness T object,
+        Funnel<? super T> funnel,
+        int numHashFunctions,
+        LockFreeBitArray bits);
 
     /**
      * Queries {@code numHashFunctions} bits of the given bit array, by hashing a user element;
      * returns {@code true} if and only if all selected bits are set.
      */
-    <T> boolean mightContain(
-        T object, Funnel<? super T> funnel, int numHashFunctions, LockFreeBitArray bits);
+    <T extends @Nullable Object> boolean mightContain(
+        @ParametricNullness T object,
+        Funnel<? super T> funnel,
+        int numHashFunctions,
+        LockFreeBitArray bits);
 
     /**
      * Identifier used to encode this strategy, when marshalled as part of a BloomFilter. Only
@@ -134,7 +143,7 @@ public BloomFilter<T> copy() {
    * Returns {@code true} if the element <i>might</i> have been put in this Bloom filter, {@code
    * false} if this is <i>definitely</i> not the case.
    */
-  public boolean mightContain(T object) {
+  public boolean mightContain(@ParametricNullness T object) {
     return strategy.mightContain(object, funnel, numHashFunctions, bits);
   }
 
@@ -144,7 +153,7 @@ public boolean mightContain(T object) {
    */
   @Deprecated
   @Override
-  public boolean apply(T input) {
+  public boolean apply(@ParametricNullness T input) {
     return mightContain(input);
   }
 
@@ -160,7 +169,7 @@ public boolean apply(T input) {
    * @since 12.0 (present in 11.0 with {@code void} return type})
    */
   @CanIgnoreReturnValue
-  public boolean put(T object) {
+  public boolean put(@ParametricNullness T object) {
     return strategy.put(object, funnel, numHashFunctions, bits);
   }
 
@@ -267,7 +276,7 @@ public void putAll(BloomFilter<T> that) {
   }
 
   @Override
-  public boolean equals(@NullableDecl Object object) {
+  public boolean equals(@CheckForNull Object object) {
     if (object == this) {
       return true;
     }
@@ -306,7 +315,7 @@ public int hashCode() {
    * @param fpp the desired false positive probability (must be positive and less than 1.0)
    * @return a {@code BloomFilter}
    */
-  public static <T> BloomFilter<T> create(
+  public static <T extends @Nullable Object> BloomFilter<T> create(
       Funnel<? super T> funnel, int expectedInsertions, double fpp) {
     return create(funnel, (long) expectedInsertions, fpp);
   }
@@ -332,13 +341,13 @@ public static <T> BloomFilter<T> create(
    * @return a {@code BloomFilter}
    * @since 19.0
    */
-  public static <T> BloomFilter<T> create(
+  public static <T extends @Nullable Object> BloomFilter<T> create(
       Funnel<? super T> funnel, long expectedInsertions, double fpp) {
     return create(funnel, expectedInsertions, fpp, BloomFilterStrategies.MURMUR128_MITZ_64);
   }
 
   @VisibleForTesting
-  static <T> BloomFilter<T> create(
+  static <T extends @Nullable Object> BloomFilter<T> create(
       Funnel<? super T> funnel, long expectedInsertions, double fpp, Strategy strategy) {
     checkNotNull(funnel);
     checkArgument(
@@ -383,7 +392,8 @@ static <T> BloomFilter<T> create(
    *     BloomFilter}; must be positive
    * @return a {@code BloomFilter}
    */
-  public static <T> BloomFilter<T> create(Funnel<? super T> funnel, int expectedInsertions) {
+  public static <T extends @Nullable Object> BloomFilter<T> create(
+      Funnel<? super T> funnel, int expectedInsertions) {
     return create(funnel, (long) expectedInsertions);
   }
 
@@ -407,7 +417,8 @@ public static <T> BloomFilter<T> create(Funnel<? super T> funnel, int expectedIn
    * @return a {@code BloomFilter}
    * @since 19.0
    */
-  public static <T> BloomFilter<T> create(Funnel<? super T> funnel, long expectedInsertions) {
+  public static <T extends @Nullable Object> BloomFilter<T> create(
+      Funnel<? super T> funnel, long expectedInsertions) {
     return create(funnel, expectedInsertions, 0.03); // FYI, for 3%, we always get 5 hash functions
   }
 
@@ -460,7 +471,7 @@ private Object writeReplace() {
     return new SerialForm<T>(this);
   }
 
-  private static class SerialForm<T> implements Serializable {
+  private static class SerialForm<T extends @Nullable Object> implements Serializable {
     final long[] data;
     final int numHashFunctions;
     final Funnel<? super T> funnel;
@@ -513,8 +524,8 @@ public void writeTo(OutputStream out) throws IOException {
    * @throws IOException if the InputStream throws an {@code IOException}, or if its data does not
    *     appear to be a BloomFilter serialized using the {@linkplain #writeTo(OutputStream)} method.
    */
-  public static <T> BloomFilter<T> readFrom(InputStream in, Funnel<? super T> funnel)
-      throws IOException {
+  public static <T extends @Nullable Object> BloomFilter<T> readFrom(
+      InputStream in, Funnel<? super T> funnel) throws IOException {
     checkNotNull(in, "InputStream");
     checkNotNull(funnel, "Funnel");
     int strategyOrdinal = -1;
@@ -530,11 +541,13 @@ public static <T> BloomFilter<T> readFrom(InputStream in, Funnel<? super T> funn
       dataLength = din.readInt();
 
       Strategy strategy = BloomFilterStrategies.values()[strategyOrdinal];
-      long[] data = new long[dataLength];
-      for (int i = 0; i < data.length; i++) {
-        data[i] = din.readLong();
+
+      LockFreeBitArray dataArray = new LockFreeBitArray(LongMath.checkedMultiply(dataLength, 64L));
+      for (int i = 0; i < dataLength; i++) {
+        dataArray.putData(i, din.readLong());
       }
-      return new BloomFilter<T>(new LockFreeBitArray(data), numHashFunctions, funnel, strategy);
+
+      return new BloomFilter<T>(dataArray, numHashFunctions, funnel, strategy);
     } catch (RuntimeException e) {
       String message =
           "Unable to deserialize BloomFilter from InputStream."
diff --git a/android/guava/src/com/google/common/hash/BloomFilterStrategies.java b/android/guava/src/com/google/common/hash/BloomFilterStrategies.java
index ade2940f320f..876269e9ce2b 100644
--- a/android/guava/src/com/google/common/hash/BloomFilterStrategies.java
+++ b/android/guava/src/com/google/common/hash/BloomFilterStrategies.java
@@ -22,7 +22,8 @@
 import java.math.RoundingMode;
 import java.util.Arrays;
 import java.util.concurrent.atomic.AtomicLongArray;
-import org.checkerframework.checker.nullness.compatqual.NullableDecl;
+import javax.annotation.CheckForNull;
+import org.checkerframework.checker.nullness.qual.Nullable;
 
 /**
  * Collections of strategies of generating the k * log(M) bits required for an element to be mapped
@@ -36,6 +37,7 @@
  * @author Dimitris Andreou
  * @author Kurt Alfred Kluever
  */
+@ElementTypesAreNonnullByDefault
 enum BloomFilterStrategies implements BloomFilter.Strategy {
   /**
    * See "Less Hashing, Same Performance: Building a Better Bloom Filter" by Adam Kirsch and Michael
@@ -44,8 +46,11 @@ enum BloomFilterStrategies implements BloomFilter.Strategy {
    */
   MURMUR128_MITZ_32() {
     @Override
-    public <T> boolean put(
-        T object, Funnel<? super T> funnel, int numHashFunctions, LockFreeBitArray bits) {
+    public <T extends @Nullable Object> boolean put(
+        @ParametricNullness T object,
+        Funnel<? super T> funnel,
+        int numHashFunctions,
+        LockFreeBitArray bits) {
       long bitSize = bits.bitSize();
       long hash64 = Hashing.murmur3_128().hashObject(object, funnel).asLong();
       int hash1 = (int) hash64;
@@ -64,8 +69,11 @@ public <T> boolean put(
     }
 
     @Override
-    public <T> boolean mightContain(
-        T object, Funnel<? super T> funnel, int numHashFunctions, LockFreeBitArray bits) {
+    public <T extends @Nullable Object> boolean mightContain(
+        @ParametricNullness T object,
+        Funnel<? super T> funnel,
+        int numHashFunctions,
+        LockFreeBitArray bits) {
       long bitSize = bits.bitSize();
       long hash64 = Hashing.murmur3_128().hashObject(object, funnel).asLong();
       int hash1 = (int) hash64;
@@ -92,8 +100,11 @@ public <T> boolean mightContain(
    */
   MURMUR128_MITZ_64() {
     @Override
-    public <T> boolean put(
-        T object, Funnel<? super T> funnel, int numHashFunctions, LockFreeBitArray bits) {
+    public <T extends @Nullable Object> boolean put(
+        @ParametricNullness T object,
+        Funnel<? super T> funnel,
+        int numHashFunctions,
+        LockFreeBitArray bits) {
       long bitSize = bits.bitSize();
       byte[] bytes = Hashing.murmur3_128().hashObject(object, funnel).getBytesInternal();
       long hash1 = lowerEight(bytes);
@@ -110,8 +121,11 @@ public <T> boolean put(
     }
 
     @Override
-    public <T> boolean mightContain(
-        T object, Funnel<? super T> funnel, int numHashFunctions, LockFreeBitArray bits) {
+    public <T extends @Nullable Object> boolean mightContain(
+        @ParametricNullness T object,
+        Funnel<? super T> funnel,
+        int numHashFunctions,
+        LockFreeBitArray bits) {
       long bitSize = bits.bitSize();
       byte[] bytes = Hashing.murmur3_128().hashObject(object, funnel).getBytesInternal();
       long hash1 = lowerEight(bytes);
@@ -249,29 +263,40 @@ void putAll(LockFreeBitArray other) {
           data.length(),
           other.data.length());
       for (int i = 0; i < data.length(); i++) {
-        long otherLong = other.data.get(i);
-
-        long ourLongOld;
-        long ourLongNew;
-        boolean changedAnyBits = true;
-        do {
-          ourLongOld = data.get(i);
-          ourLongNew = ourLongOld | otherLong;
-          if (ourLongOld == ourLongNew) {
-            changedAnyBits = false;
-            break;
-          }
-        } while (!data.compareAndSet(i, ourLongOld, ourLongNew));
+        putData(i, other.data.get(i));
+      }
+    }
 
-        if (changedAnyBits) {
-          int bitsAdded = Long.bitCount(ourLongNew) - Long.bitCount(ourLongOld);
-          bitCount.add(bitsAdded);
+    /**
+     * ORs the bits encoded in the {@code i}th {@code long} in the underlying {@link
+     * AtomicLongArray} with the given value.
+     */
+    void putData(int i, long longValue) {
+      long ourLongOld;
+      long ourLongNew;
+      boolean changedAnyBits = true;
+      do {
+        ourLongOld = data.get(i);
+        ourLongNew = ourLongOld | longValue;
+        if (ourLongOld == ourLongNew) {
+          changedAnyBits = false;
+          break;
         }
+      } while (!data.compareAndSet(i, ourLongOld, ourLongNew));
+
+      if (changedAnyBits) {
+        int bitsAdded = Long.bitCount(ourLongNew) - Long.bitCount(ourLongOld);
+        bitCount.add(bitsAdded);
       }
     }
 
+    /** Returns the number of {@code long}s in the underlying {@link AtomicLongArray}. */
+    int dataLength() {
+      return data.length();
+    }
+
     @Override
-    public boolean equals(@NullableDecl Object o) {
+    public boolean equals(@CheckForNull Object o) {
       if (o instanceof LockFreeBitArray) {
         LockFreeBitArray lockFreeBitArray = (LockFreeBitArray) o;
         // TODO(lowasser): avoid allocation here
diff --git a/android/guava/src/com/google/common/hash/ChecksumHashFunction.java b/android/guava/src/com/google/common/hash/ChecksumHashFunction.java
index 380c3a39ab6e..159adbb8194b 100644
--- a/android/guava/src/com/google/common/hash/ChecksumHashFunction.java
+++ b/android/guava/src/com/google/common/hash/ChecksumHashFunction.java
@@ -27,6 +27,7 @@
  * @author Colin Decker
  */
 @Immutable
+@ElementTypesAreNonnullByDefault
 final class ChecksumHashFunction extends AbstractHashFunction implements Serializable {
   private final ImmutableSupplier<? extends Checksum> checksumSupplier;
   private final int bits;
diff --git a/android/guava/src/com/google/common/hash/Crc32cHashFunction.java b/android/guava/src/com/google/common/hash/Crc32cHashFunction.java
index f965178dddef..8e17e6538c21 100644
--- a/android/guava/src/com/google/common/hash/Crc32cHashFunction.java
+++ b/android/guava/src/com/google/common/hash/Crc32cHashFunction.java
@@ -24,6 +24,7 @@
  * @author Kurt Alfred Kluever
  */
 @Immutable
+@ElementTypesAreNonnullByDefault
 final class Crc32cHashFunction extends AbstractHashFunction {
   static final HashFunction CRC_32_C = new Crc32cHashFunction();
 
diff --git a/android/guava/src/com/google/common/hash/ElementTypesAreNonnullByDefault.java b/android/guava/src/com/google/common/hash/ElementTypesAreNonnullByDefault.java
new file mode 100644
index 000000000000..a2382b3514cc
--- /dev/null
+++ b/android/guava/src/com/google/common/hash/ElementTypesAreNonnullByDefault.java
@@ -0,0 +1,41 @@
+/*
+ * Copyright (C) 2021 The Guava Authors
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package com.google.common.hash;
+
+import static java.lang.annotation.ElementType.FIELD;
+import static java.lang.annotation.ElementType.METHOD;
+import static java.lang.annotation.ElementType.PARAMETER;
+import static java.lang.annotation.ElementType.TYPE;
+import static java.lang.annotation.RetentionPolicy.RUNTIME;
+
+import com.google.common.annotations.GwtCompatible;
+import java.lang.annotation.Retention;
+import java.lang.annotation.Target;
+import javax.annotation.Nonnull;
+import javax.annotation.meta.TypeQualifierDefault;
+
+/**
+ * Marks all "top-level" types as non-null in a way that is recognized by Kotlin. Note that this
+ * unfortunately includes type-variable usages, so we also provide {@link ParametricNullness} to
+ * "undo" it as best we can.
+ */
+@GwtCompatible
+@Retention(RUNTIME)
+@Target(TYPE)
+@TypeQualifierDefault({FIELD, METHOD, PARAMETER})
+@Nonnull
+@interface ElementTypesAreNonnullByDefault {}
diff --git a/android/guava/src/com/google/common/hash/FarmHashFingerprint64.java b/android/guava/src/com/google/common/hash/FarmHashFingerprint64.java
index 30eab5fadf8e..3437b00a2167 100644
--- a/android/guava/src/com/google/common/hash/FarmHashFingerprint64.java
+++ b/android/guava/src/com/google/common/hash/FarmHashFingerprint64.java
@@ -38,6 +38,7 @@
  * @author Kyle Maddison
  * @author Geoff Pike
  */
+@ElementTypesAreNonnullByDefault
 final class FarmHashFingerprint64 extends AbstractNonStreamingHashFunction {
   static final HashFunction FARMHASH_FINGERPRINT_64 = new FarmHashFingerprint64();
 
@@ -169,7 +170,7 @@ private static long hashLength33To64(byte[] bytes, int offset, int length) {
    * Compute an 8-byte hash of a byte array of length greater than 64 bytes.
    */
   private static long hashLength65Plus(byte[] bytes, int offset, int length) {
-    final int seed = 81;
+    int seed = 81;
     // For strings over 64 bytes we loop. Internal state consists of 56 bytes: v, w, x, y, and z.
     long x = seed;
     @SuppressWarnings("ConstantOverflow")
diff --git a/android/guava/src/com/google/common/hash/Fingerprint2011.java b/android/guava/src/com/google/common/hash/Fingerprint2011.java
new file mode 100644
index 000000000000..1b01e0092418
--- /dev/null
+++ b/android/guava/src/com/google/common/hash/Fingerprint2011.java
@@ -0,0 +1,198 @@
+// Copyright 2011 Google Inc. All Rights Reserved.
+
+package com.google.common.hash;
+
+import static com.google.common.base.Preconditions.checkPositionIndexes;
+import static com.google.common.hash.LittleEndianByteArray.load64;
+import static com.google.common.hash.LittleEndianByteArray.load64Safely;
+import static java.lang.Long.rotateRight;
+
+import com.google.common.annotations.VisibleForTesting;
+
+/**
+ * Implementation of Geoff Pike's fingerprint2011 hash function. See {@link Hashing#fingerprint2011}
+ * for information on the behaviour of the algorithm.
+ *
+ * <p>On Intel Core2 2.66, on 1000 bytes, fingerprint2011 takes 0.9 microseconds compared to
+ * fingerprint at 4.0 microseconds and md5 at 4.5 microseconds.
+ *
+ * <p>Note to maintainers: This implementation relies on signed arithmetic being bit-wise equivalent
+ * to unsigned arithmetic in all cases except:
+ *
+ * <ul>
+ *   <li>comparisons (signed values can be negative)
+ *   <li>division (avoided here)
+ *   <li>shifting (right shift must be unsigned)
+ * </ul>
+ *
+ * @author kylemaddison@google.com (Kyle Maddison)
+ * @author gpike@google.com (Geoff Pike)
+ */
+@ElementTypesAreNonnullByDefault
+final class Fingerprint2011 extends AbstractNonStreamingHashFunction {
+  static final HashFunction FINGERPRINT_2011 = new Fingerprint2011();
+
+  // Some primes between 2^63 and 2^64 for various uses.
+  private static final long K0 = 0xa5b85c5e198ed849L;
+  private static final long K1 = 0x8d58ac26afe12e47L;
+  private static final long K2 = 0xc47b6e9e3a970ed3L;
+  private static final long K3 = 0xc6a4a7935bd1e995L;
+
+  @Override
+  public HashCode hashBytes(byte[] input, int off, int len) {
+    checkPositionIndexes(off, off + len, input.length);
+    return HashCode.fromLong(fingerprint(input, off, len));
+  }
+
+  @Override
+  public int bits() {
+    return 64;
+  }
+
+  @Override
+  public String toString() {
+    return "Hashing.fingerprint2011()";
+  }
+
+  // End of public functions.
+
+  @VisibleForTesting
+  static long fingerprint(byte[] bytes, int offset, int length) {
+    long result;
+
+    if (length <= 32) {
+      result = murmurHash64WithSeed(bytes, offset, length, K0 ^ K1 ^ K2);
+    } else if (length <= 64) {
+      result = hashLength33To64(bytes, offset, length);
+    } else {
+      result = fullFingerprint(bytes, offset, length);
+    }
+
+    long u = length >= 8 ? load64(bytes, offset) : K0;
+    long v = length >= 9 ? load64(bytes, offset + length - 8) : K0;
+    result = hash128to64(result + v, u);
+    return result == 0 || result == 1 ? result + ~1 : result;
+  }
+
+  private static long shiftMix(long val) {
+    return val ^ (val >>> 47);
+  }
+
+  /** Implementation of Hash128to64 from util/hash/hash128to64.h */
+  @VisibleForTesting
+  static long hash128to64(long high, long low) {
+    long a = (low ^ high) * K3;
+    a ^= (a >>> 47);
+    long b = (high ^ a) * K3;
+    b ^= (b >>> 47);
+    b *= K3;
+    return b;
+  }
+
+  /**
+   * Computes intermediate hash of 32 bytes of byte array from the given offset. Results are
+   * returned in the output array - this is 12% faster than allocating new arrays every time.
+   */
+  private static void weakHashLength32WithSeeds(
+      byte[] bytes, int offset, long seedA, long seedB, long[] output) {
+    long part1 = load64(bytes, offset);
+    long part2 = load64(bytes, offset + 8);
+    long part3 = load64(bytes, offset + 16);
+    long part4 = load64(bytes, offset + 24);
+
+    seedA += part1;
+    seedB = rotateRight(seedB + seedA + part4, 51);
+    long c = seedA;
+    seedA += part2;
+    seedA += part3;
+    seedB += rotateRight(seedA, 23);
+    output[0] = seedA + part4;
+    output[1] = seedB + c;
+  }
+
+  /*
+   * Compute an 8-byte hash of a byte array of length greater than 64 bytes.
+   */
+  private static long fullFingerprint(byte[] bytes, int offset, int length) {
+    // For lengths over 64 bytes we hash the end first, and then as we
+    // loop we keep 56 bytes of state: v, w, x, y, and z.
+    long x = load64(bytes, offset);
+    long y = load64(bytes, offset + length - 16) ^ K1;
+    long z = load64(bytes, offset + length - 56) ^ K0;
+    long[] v = new long[2];
+    long[] w = new long[2];
+    weakHashLength32WithSeeds(bytes, offset + length - 64, length, y, v);
+    weakHashLength32WithSeeds(bytes, offset + length - 32, length * K1, K0, w);
+    z += shiftMix(v[1]) * K1;
+    x = rotateRight(z + x, 39) * K1;
+    y = rotateRight(y, 33) * K1;
+
+    // Decrease length to the nearest multiple of 64, and operate on 64-byte chunks.
+    length = (length - 1) & ~63;
+    do {
+      x = rotateRight(x + y + v[0] + load64(bytes, offset + 16), 37) * K1;
+      y = rotateRight(y + v[1] + load64(bytes, offset + 48), 42) * K1;
+      x ^= w[1];
+      y ^= v[0];
+      z = rotateRight(z ^ w[0], 33);
+      weakHashLength32WithSeeds(bytes, offset, v[1] * K1, x + w[0], v);
+      weakHashLength32WithSeeds(bytes, offset + 32, z + w[1], y, w);
+      long tmp = z;
+      z = x;
+      x = tmp;
+      offset += 64;
+      length -= 64;
+    } while (length != 0);
+    return hash128to64(hash128to64(v[0], w[0]) + shiftMix(y) * K1 + z, hash128to64(v[1], w[1]) + x);
+  }
+
+  private static long hashLength33To64(byte[] bytes, int offset, int length) {
+    long z = load64(bytes, offset + 24);
+    long a = load64(bytes, offset) + (length + load64(bytes, offset + length - 16)) * K0;
+    long b = rotateRight(a + z, 52);
+    long c = rotateRight(a, 37);
+    a += load64(bytes, offset + 8);
+    c += rotateRight(a, 7);
+    a += load64(bytes, offset + 16);
+    long vf = a + z;
+    long vs = b + rotateRight(a, 31) + c;
+    a = load64(bytes, offset + 16) + load64(bytes, offset + length - 32);
+    z = load64(bytes, offset + length - 8);
+    b = rotateRight(a + z, 52);
+    c = rotateRight(a, 37);
+    a += load64(bytes, offset + length - 24);
+    c += rotateRight(a, 7);
+    a += load64(bytes, offset + length - 16);
+    long wf = a + z;
+    long ws = b + rotateRight(a, 31) + c;
+    long r = shiftMix((vf + ws) * K2 + (wf + vs) * K0);
+    return shiftMix(r * K0 + vs) * K2;
+  }
+
+  @VisibleForTesting
+  static long murmurHash64WithSeed(byte[] bytes, int offset, int length, long seed) {
+    long mul = K3;
+    int topBit = 0x7;
+
+    int lengthAligned = length & ~topBit;
+    int lengthRemainder = length & topBit;
+    long hash = seed ^ (length * mul);
+
+    for (int i = 0; i < lengthAligned; i += 8) {
+      long loaded = load64(bytes, offset + i);
+      long data = shiftMix(loaded * mul) * mul;
+      hash ^= data;
+      hash *= mul;
+    }
+
+    if (lengthRemainder != 0) {
+      long data = load64Safely(bytes, offset + lengthAligned, lengthRemainder);
+      hash ^= data;
+      hash *= mul;
+    }
+
+    hash = shiftMix(hash) * mul;
+    hash = shiftMix(hash);
+    return hash;
+  }
+}
diff --git a/android/guava/src/com/google/common/hash/Funnel.java b/android/guava/src/com/google/common/hash/Funnel.java
index 2c6a7b9820f5..9d80dabcf6ed 100644
--- a/android/guava/src/com/google/common/hash/Funnel.java
+++ b/android/guava/src/com/google/common/hash/Funnel.java
@@ -17,6 +17,7 @@
 import com.google.common.annotations.Beta;
 import com.google.errorprone.annotations.DoNotMock;
 import java.io.Serializable;
+import org.checkerframework.checker.nullness.qual.Nullable;
 
 /**
  * An object which can send data from an object of type {@code T} into a {@code PrimitiveSink}.
@@ -43,7 +44,8 @@
  */
 @Beta
 @DoNotMock("Implement with a lambda")
-public interface Funnel<T> extends Serializable {
+@ElementTypesAreNonnullByDefault
+public interface Funnel<T extends @Nullable Object> extends Serializable {
 
   /**
    * Sends a stream of data from the {@code from} object into the sink {@code into}. There is no
@@ -51,5 +53,5 @@ public interface Funnel<T> extends Serializable {
    *
    * @since 12.0 (in Guava 11.0, {@code PrimitiveSink} was named {@code Sink})
    */
-  void funnel(T from, PrimitiveSink into);
+  void funnel(@ParametricNullness T from, PrimitiveSink into);
 }
diff --git a/android/guava/src/com/google/common/hash/Funnels.java b/android/guava/src/com/google/common/hash/Funnels.java
index afe60c176385..b8e63d504ddb 100644
--- a/android/guava/src/com/google/common/hash/Funnels.java
+++ b/android/guava/src/com/google/common/hash/Funnels.java
@@ -19,7 +19,8 @@
 import java.io.OutputStream;
 import java.io.Serializable;
 import java.nio.charset.Charset;
-import org.checkerframework.checker.nullness.compatqual.NullableDecl;
+import javax.annotation.CheckForNull;
+import org.checkerframework.checker.nullness.qual.Nullable;
 
 /**
  * Funnels for common types. All implementations are serializable.
@@ -28,6 +29,7 @@
  * @since 11.0
  */
 @Beta
+@ElementTypesAreNonnullByDefault
 public final class Funnels {
   private Funnels() {}
 
@@ -103,7 +105,7 @@ public String toString() {
     }
 
     @Override
-    public boolean equals(@NullableDecl Object o) {
+    public boolean equals(@CheckForNull Object o) {
       if (o instanceof StringCharsetFunnel) {
         StringCharsetFunnel funnel = (StringCharsetFunnel) o;
         return this.charset.equals(funnel.charset);
@@ -164,11 +166,13 @@ public String toString() {
    *
    * @since 15.0
    */
-  public static <E> Funnel<Iterable<? extends E>> sequentialFunnel(Funnel<E> elementFunnel) {
-    return new SequentialFunnel<E>(elementFunnel);
+  public static <E extends @Nullable Object> Funnel<Iterable<? extends E>> sequentialFunnel(
+      Funnel<E> elementFunnel) {
+    return new SequentialFunnel<>(elementFunnel);
   }
 
-  private static class SequentialFunnel<E> implements Funnel<Iterable<? extends E>>, Serializable {
+  private static class SequentialFunnel<E extends @Nullable Object>
+      implements Funnel<Iterable<? extends E>>, Serializable {
     private final Funnel<E> elementFunnel;
 
     SequentialFunnel(Funnel<E> elementFunnel) {
@@ -188,7 +192,7 @@ public String toString() {
     }
 
     @Override
-    public boolean equals(@NullableDecl Object o) {
+    public boolean equals(@CheckForNull Object o) {
       if (o instanceof SequentialFunnel) {
         SequentialFunnel<?> funnel = (SequentialFunnel<?>) o;
         return elementFunnel.equals(funnel.elementFunnel);
diff --git a/android/guava/src/com/google/common/hash/HashCode.java b/android/guava/src/com/google/common/hash/HashCode.java
index 44eb9a12e34d..fde2a86d6466 100644
--- a/android/guava/src/com/google/common/hash/HashCode.java
+++ b/android/guava/src/com/google/common/hash/HashCode.java
@@ -23,7 +23,7 @@
 import com.google.common.primitives.UnsignedInts;
 import com.google.errorprone.annotations.CanIgnoreReturnValue;
 import java.io.Serializable;
-import org.checkerframework.checker.nullness.compatqual.NullableDecl;
+import javax.annotation.CheckForNull;
 
 /**
  * An immutable hash code of arbitrary bit length.
@@ -32,6 +32,7 @@
  * @author Kurt Alfred Kluever
  * @since 11.0
  */
+@ElementTypesAreNonnullByDefault
 public abstract class HashCode {
   HashCode() {}
 
@@ -367,7 +368,7 @@ private static int decode(char ch) {
    * to protect against <a href="http://en.wikipedia.org/wiki/Timing_attack">timing attacks</a>.
    */
   @Override
-  public final boolean equals(@NullableDecl Object object) {
+  public final boolean equals(@CheckForNull Object object) {
     if (object instanceof HashCode) {
       HashCode that = (HashCode) object;
       return bits() == that.bits() && equalsSameBits(that);
diff --git a/android/guava/src/com/google/common/hash/HashFunction.java b/android/guava/src/com/google/common/hash/HashFunction.java
index 78842595f692..d4b7f8a01fcc 100644
--- a/android/guava/src/com/google/common/hash/HashFunction.java
+++ b/android/guava/src/com/google/common/hash/HashFunction.java
@@ -14,11 +14,11 @@
 
 package com.google.common.hash;
 
-import com.google.common.annotations.Beta;
 import com.google.common.primitives.Ints;
 import com.google.errorprone.annotations.Immutable;
 import java.nio.ByteBuffer;
 import java.nio.charset.Charset;
+import org.checkerframework.checker.nullness.qual.Nullable;
 
 /**
  * A hash function is a collision-averse pure function that maps an arbitrary block of data to a
@@ -115,8 +115,8 @@
  * @author Kevin Bourrillion
  * @since 11.0
  */
-@Beta
 @Immutable
+@ElementTypesAreNonnullByDefault
 public interface HashFunction {
   /**
    * Begins a new hash code computation by returning an initialized, stateful {@code Hasher}
@@ -211,7 +211,8 @@ public interface HashFunction {
    *
    * @since 14.0
    */
-  <T> HashCode hashObject(T instance, Funnel<? super T> funnel);
+  <T extends @Nullable Object> HashCode hashObject(
+      @ParametricNullness T instance, Funnel<? super T> funnel);
 
   /**
    * Returns the number of bits (a multiple of 32) that each hash code produced by this hash
diff --git a/android/guava/src/com/google/common/hash/Hasher.java b/android/guava/src/com/google/common/hash/Hasher.java
index ae9ae5f68ff6..b3f24fa282b9 100644
--- a/android/guava/src/com/google/common/hash/Hasher.java
+++ b/android/guava/src/com/google/common/hash/Hasher.java
@@ -18,6 +18,7 @@
 import com.google.errorprone.annotations.CanIgnoreReturnValue;
 import java.nio.ByteBuffer;
 import java.nio.charset.Charset;
+import org.checkerframework.checker.nullness.qual.Nullable;
 
 /**
  * A {@link PrimitiveSink} that can compute a hash code after reading the input. Each hasher should
@@ -54,6 +55,7 @@
  */
 @Beta
 @CanIgnoreReturnValue
+@ElementTypesAreNonnullByDefault
 public interface Hasher extends PrimitiveSink {
   @Override
   Hasher putByte(byte b);
@@ -119,7 +121,8 @@ public interface Hasher extends PrimitiveSink {
   Hasher putString(CharSequence charSequence, Charset charset);
 
   /** A simple convenience for {@code funnel.funnel(object, this)}. */
-  <T> Hasher putObject(T instance, Funnel<? super T> funnel);
+  <T extends @Nullable Object> Hasher putObject(
+      @ParametricNullness T instance, Funnel<? super T> funnel);
 
   /**
    * Computes a hash code based on the data that have been provided to this hasher. The result is
diff --git a/android/guava/src/com/google/common/hash/Hashing.java b/android/guava/src/com/google/common/hash/Hashing.java
index 4119056a9efb..afff20c74937 100644
--- a/android/guava/src/com/google/common/hash/Hashing.java
+++ b/android/guava/src/com/google/common/hash/Hashing.java
@@ -17,18 +17,18 @@
 import static com.google.common.base.Preconditions.checkArgument;
 import static com.google.common.base.Preconditions.checkNotNull;
 
-import com.google.common.annotations.Beta;
 import com.google.errorprone.annotations.Immutable;
 import java.security.Key;
 import java.util.ArrayList;
 import java.util.Arrays;
+import java.util.Collections;
 import java.util.Iterator;
 import java.util.List;
 import java.util.zip.Adler32;
 import java.util.zip.CRC32;
 import java.util.zip.Checksum;
+import javax.annotation.CheckForNull;
 import javax.crypto.spec.SecretKeySpec;
-import org.checkerframework.checker.nullness.compatqual.NullableDecl;
 
 /**
  * Static methods to obtain {@link HashFunction} instances, and other static hashing-related
@@ -42,7 +42,7 @@
  * @author Kurt Alfred Kluever
  * @since 11.0
  */
-@Beta
+@ElementTypesAreNonnullByDefault
 public final class Hashing {
   /**
    * Returns a general-purpose, <b>temporary-use</b>, non-cryptographic hash function. The algorithm
@@ -90,15 +90,56 @@ public static HashFunction goodFastHash(int minimumBits) {
   @SuppressWarnings("GoodTime") // reading system time without TimeSource
   static final int GOOD_FAST_HASH_SEED = (int) System.currentTimeMillis();
 
+  /**
+   * Returns a hash function implementing the <a
+   * href="https://github.com/aappleby/smhasher/blob/master/src/MurmurHash3.cpp">32-bit murmur3
+   * algorithm, x86 variant</a> (little-endian variant), using the given seed value, <b>with a known
+   * bug</b> as described in the deprecation text.
+   *
+   * <p>The C++ equivalent is the MurmurHash3_x86_32 function (Murmur3A), which however does not
+   * have the bug.
+   *
+   * @deprecated This implementation produces incorrect hash values from the {@link
+   *     HashFunction#hashString} method if the string contains non-BMP characters. Use {@link
+   *     #murmur3_32_fixed(int)} instead.
+   */
+  @Deprecated
+  public static HashFunction murmur3_32(int seed) {
+    return new Murmur3_32HashFunction(seed, /* supplementaryPlaneFix= */ false);
+  }
+
+  /**
+   * Returns a hash function implementing the <a
+   * href="https://github.com/aappleby/smhasher/blob/master/src/MurmurHash3.cpp">32-bit murmur3
+   * algorithm, x86 variant</a> (little-endian variant), using the given seed value, <b>with a known
+   * bug</b> as described in the deprecation text.
+   *
+   * <p>The C++ equivalent is the MurmurHash3_x86_32 function (Murmur3A), which however does not
+   * have the bug.
+   *
+   * @deprecated This implementation produces incorrect hash values from the {@link
+   *     HashFunction#hashString} method if the string contains non-BMP characters. Use {@link
+   *     #murmur3_32_fixed()} instead.
+   */
+  @Deprecated
+  public static HashFunction murmur3_32() {
+    return Murmur3_32HashFunction.MURMUR3_32;
+  }
+
   /**
    * Returns a hash function implementing the <a
    * href="https://github.com/aappleby/smhasher/blob/master/src/MurmurHash3.cpp">32-bit murmur3
    * algorithm, x86 variant</a> (little-endian variant), using the given seed value.
    *
    * <p>The exact C++ equivalent is the MurmurHash3_x86_32 function (Murmur3A).
+   *
+   * <p>This method is called {@code murmur3_32_fixed} because it fixes a bug in the {@code
+   * HashFunction} returned by the original {@code murmur3_32} method.
+   *
+   * @since 31.0
    */
-  public static HashFunction murmur3_32(int seed) {
-    return new Murmur3_32HashFunction(seed);
+  public static HashFunction murmur3_32_fixed(int seed) {
+    return new Murmur3_32HashFunction(seed, /* supplementaryPlaneFix= */ true);
   }
 
   /**
@@ -107,9 +148,14 @@ public static HashFunction murmur3_32(int seed) {
    * algorithm, x86 variant</a> (little-endian variant), using a seed value of zero.
    *
    * <p>The exact C++ equivalent is the MurmurHash3_x86_32 function (Murmur3A).
+   *
+   * <p>This method is called {@code murmur3_32_fixed} because it fixes a bug in the {@code
+   * HashFunction} returned by the original {@code murmur3_32} method.
+   *
+   * @since 31.0
    */
-  public static HashFunction murmur3_32() {
-    return Murmur3_32HashFunction.MURMUR3_32;
+  public static HashFunction murmur3_32_fixed() {
+    return Murmur3_32HashFunction.MURMUR3_32_FIXED;
   }
 
   /**
@@ -422,6 +468,30 @@ public static HashFunction farmHashFingerprint64() {
     return FarmHashFingerprint64.FARMHASH_FINGERPRINT_64;
   }
 
+  /**
+   * Returns a hash function implementing the Fingerprint2011 hashing function (64 hash bits).
+   *
+   * <p>This is designed for generating persistent fingerprints of strings. It isn't
+   * cryptographically secure, but it produces a high-quality hash with few collisions. Fingerprints
+   * generated using this are byte-wise identical to those created using the C++ version, but note
+   * that this uses unsigned integers (see {@link com.google.common.primitives.UnsignedInts}).
+   * Comparisons between the two should take this into account.
+   *
+   * <p>Fingerprint2011() is a form of Murmur2 on strings up to 32 bytes and a form of CityHash for
+   * longer strings. It could have been one or the other throughout. The main advantage of the
+   * combination is that CityHash has a bunch of special cases for short strings that don't need to
+   * be replicated here. The result will never be 0 or 1.
+   *
+   * <p>This function is best understood as a <a
+   * href="https://en.wikipedia.org/wiki/Fingerprint_(computing)">fingerprint</a> rather than a true
+   * <a href="https://en.wikipedia.org/wiki/Hash_function">hash function</a>.
+   *
+   * @since 31.1
+   */
+  public static HashFunction fingerprint2011() {
+    return Fingerprint2011.FINGERPRINT_2011;
+  }
+
   /**
    * Assigns to {@code hashCode} a "bucket" in the range {@code [0, buckets)}, in a uniform manner
    * that minimizes the need for remapping as {@code buckets} grows. That is, {@code
@@ -574,7 +644,7 @@ public static HashFunction concatenating(
     List<HashFunction> list = new ArrayList<>();
     list.add(first);
     list.add(second);
-    list.addAll(Arrays.asList(rest));
+    Collections.addAll(list, rest);
     return new ConcatenatedHashFunction(list.toArray(new HashFunction[0]));
   }
 
@@ -595,7 +665,7 @@ public static HashFunction concatenating(Iterable<HashFunction> hashFunctions) {
     for (HashFunction hashFunction : hashFunctions) {
       list.add(hashFunction);
     }
-    checkArgument(list.size() > 0, "number of hash functions (%s) must be > 0", list.size());
+    checkArgument(!list.isEmpty(), "number of hash functions (%s) must be > 0", list.size());
     return new ConcatenatedHashFunction(list.toArray(new HashFunction[0]));
   }
 
@@ -633,7 +703,7 @@ public int bits() {
     }
 
     @Override
-    public boolean equals(@NullableDecl Object object) {
+    public boolean equals(@CheckForNull Object object) {
       if (object instanceof ConcatenatedHashFunction) {
         ConcatenatedHashFunction other = (ConcatenatedHashFunction) object;
         return Arrays.equals(functions, other.functions);
diff --git a/android/guava/src/com/google/common/hash/HashingInputStream.java b/android/guava/src/com/google/common/hash/HashingInputStream.java
index f49dfd62daa5..bf9464ce5573 100644
--- a/android/guava/src/com/google/common/hash/HashingInputStream.java
+++ b/android/guava/src/com/google/common/hash/HashingInputStream.java
@@ -29,6 +29,7 @@
  * @since 16.0
  */
 @Beta
+@ElementTypesAreNonnullByDefault
 public final class HashingInputStream extends FilterInputStream {
   private final Hasher hasher;
 
diff --git a/android/guava/src/com/google/common/hash/HashingOutputStream.java b/android/guava/src/com/google/common/hash/HashingOutputStream.java
index 7a1c8d8ae0db..f138bba15050 100644
--- a/android/guava/src/com/google/common/hash/HashingOutputStream.java
+++ b/android/guava/src/com/google/common/hash/HashingOutputStream.java
@@ -28,6 +28,7 @@
  * @since 16.0
  */
 @Beta
+@ElementTypesAreNonnullByDefault
 public final class HashingOutputStream extends FilterOutputStream {
   private final Hasher hasher;
 
diff --git a/android/guava/src/com/google/common/hash/ImmutableSupplier.java b/android/guava/src/com/google/common/hash/ImmutableSupplier.java
index f90352afca75..24f711a313fa 100644
--- a/android/guava/src/com/google/common/hash/ImmutableSupplier.java
+++ b/android/guava/src/com/google/common/hash/ImmutableSupplier.java
@@ -21,5 +21,7 @@
  * Explicitly named subinterface of {@link Supplier} that can be marked {@literal @}{@link
  * Immutable}.
  */
+// TODO(cpovirk): Should we just use ChecksumType directly instead of defining this type?
 @Immutable
+@ElementTypesAreNonnullByDefault
 interface ImmutableSupplier<T> extends Supplier<T> {}
diff --git a/android/guava/src/com/google/common/hash/Java8Compatibility.java b/android/guava/src/com/google/common/hash/Java8Compatibility.java
index 52f71e788558..c15f2b3cc575 100644
--- a/android/guava/src/com/google/common/hash/Java8Compatibility.java
+++ b/android/guava/src/com/google/common/hash/Java8Compatibility.java
@@ -22,6 +22,7 @@
  * https://github.com/google/guava/issues/3990
  */
 @GwtIncompatible
+@ElementTypesAreNonnullByDefault
 final class Java8Compatibility {
   static void clear(Buffer b) {
     b.clear();
diff --git a/android/guava/src/com/google/common/hash/LittleEndianByteArray.java b/android/guava/src/com/google/common/hash/LittleEndianByteArray.java
index 22ef4f044f02..625201547d1c 100644
--- a/android/guava/src/com/google/common/hash/LittleEndianByteArray.java
+++ b/android/guava/src/com/google/common/hash/LittleEndianByteArray.java
@@ -24,6 +24,7 @@
  * @author Kevin Damm
  * @author Kyle Maddison
  */
+@ElementTypesAreNonnullByDefault
 final class LittleEndianByteArray {
 
   /** The instance that actually does the work; delegates to Unsafe or a pure-Java fallback. */
@@ -242,7 +243,7 @@ public void putLongLittleEndian(byte[] sink, int offset, long value) {
        * which will have an efficient native implementation in JDK 9.
        *
        */
-      final String arch = System.getProperty("os.arch");
+      String arch = System.getProperty("os.arch");
       if ("amd64".equals(arch)) {
         theGetter =
             ByteOrder.nativeOrder().equals(ByteOrder.LITTLE_ENDIAN)
diff --git a/android/guava/src/com/google/common/hash/LongAddable.java b/android/guava/src/com/google/common/hash/LongAddable.java
index a95eece2e1ff..5c6a7f0c7db8 100644
--- a/android/guava/src/com/google/common/hash/LongAddable.java
+++ b/android/guava/src/com/google/common/hash/LongAddable.java
@@ -14,11 +14,13 @@
 
 package com.google.common.hash;
 
+
 /**
  * Abstract interface for objects that can concurrently add longs.
  *
  * @author Louis Wasserman
  */
+@ElementTypesAreNonnullByDefault
 interface LongAddable {
   void increment();
 
diff --git a/android/guava/src/com/google/common/hash/LongAddables.java b/android/guava/src/com/google/common/hash/LongAddables.java
index d2768bcf5c42..7c371ec88fdc 100644
--- a/android/guava/src/com/google/common/hash/LongAddables.java
+++ b/android/guava/src/com/google/common/hash/LongAddables.java
@@ -22,13 +22,15 @@
  *
  * @author Louis Wasserman
  */
+@ElementTypesAreNonnullByDefault
 final class LongAddables {
   private static final Supplier<LongAddable> SUPPLIER;
 
   static {
     Supplier<LongAddable> supplier;
     try {
-      new LongAdder(); // trigger static initialization of the LongAdder class, which may fail
+      // trigger static initialization of the LongAdder class, which may fail
+      LongAdder unused = new LongAdder();
       supplier =
           new Supplier<LongAddable>() {
             @Override
diff --git a/android/guava/src/com/google/common/hash/LongAdder.java b/android/guava/src/com/google/common/hash/LongAdder.java
index bd08428ff3a4..dc864aa9a417 100644
--- a/android/guava/src/com/google/common/hash/LongAdder.java
+++ b/android/guava/src/com/google/common/hash/LongAdder.java
@@ -38,6 +38,7 @@
  * @since 1.8
  * @author Doug Lea
  */
+@ElementTypesAreNonnullByDefault
 final class LongAdder extends Striped64 implements Serializable, LongAddable {
   private static final long serialVersionUID = 7249069246863182397L;
 
diff --git a/android/guava/src/com/google/common/hash/MacHashFunction.java b/android/guava/src/com/google/common/hash/MacHashFunction.java
index ed1841c36b18..6d53a54c39e2 100644
--- a/android/guava/src/com/google/common/hash/MacHashFunction.java
+++ b/android/guava/src/com/google/common/hash/MacHashFunction.java
@@ -30,6 +30,7 @@
  * @author Kurt Alfred Kluever
  */
 @Immutable
+@ElementTypesAreNonnullByDefault
 final class MacHashFunction extends AbstractHashFunction {
 
   @SuppressWarnings("Immutable") // cloned before each use
@@ -57,7 +58,7 @@ public int bits() {
 
   private static boolean supportsClone(Mac mac) {
     try {
-      mac.clone();
+      Object unused = mac.clone();
       return true;
     } catch (CloneNotSupportedException e) {
       return false;
diff --git a/android/guava/src/com/google/common/hash/MessageDigestHashFunction.java b/android/guava/src/com/google/common/hash/MessageDigestHashFunction.java
index 5c48c7d7f3ab..43fc087f28ad 100644
--- a/android/guava/src/com/google/common/hash/MessageDigestHashFunction.java
+++ b/android/guava/src/com/google/common/hash/MessageDigestHashFunction.java
@@ -32,6 +32,7 @@
  * @author Dimitris Andreou
  */
 @Immutable
+@ElementTypesAreNonnullByDefault
 final class MessageDigestHashFunction extends AbstractHashFunction implements Serializable {
 
   @SuppressWarnings("Immutable") // cloned before each use
@@ -60,7 +61,7 @@ final class MessageDigestHashFunction extends AbstractHashFunction implements Se
 
   private static boolean supportsClone(MessageDigest digest) {
     try {
-      digest.clone();
+      Object unused = digest.clone();
       return true;
     } catch (CloneNotSupportedException e) {
       return false;
diff --git a/android/guava/src/com/google/common/hash/Murmur3_128HashFunction.java b/android/guava/src/com/google/common/hash/Murmur3_128HashFunction.java
index 4403b20c6f84..d1304f8273c5 100644
--- a/android/guava/src/com/google/common/hash/Murmur3_128HashFunction.java
+++ b/android/guava/src/com/google/common/hash/Murmur3_128HashFunction.java
@@ -31,7 +31,7 @@
 import java.io.Serializable;
 import java.nio.ByteBuffer;
 import java.nio.ByteOrder;
-import org.checkerframework.checker.nullness.compatqual.NullableDecl;
+import javax.annotation.CheckForNull;
 
 /**
  * See MurmurHash3_x64_128 in <a href="http://smhasher.googlecode.com/svn/trunk/MurmurHash3.cpp">the
@@ -41,6 +41,7 @@
  * @author Dimitris Andreou
  */
 @Immutable
+@ElementTypesAreNonnullByDefault
 final class Murmur3_128HashFunction extends AbstractHashFunction implements Serializable {
   static final HashFunction MURMUR3_128 = new Murmur3_128HashFunction(0);
 
@@ -70,7 +71,7 @@ public String toString() {
   }
 
   @Override
-  public boolean equals(@NullableDecl Object object) {
+  public boolean equals(@CheckForNull Object object) {
     if (object instanceof Murmur3_128HashFunction) {
       Murmur3_128HashFunction other = (Murmur3_128HashFunction) object;
       return seed == other.seed;
diff --git a/android/guava/src/com/google/common/hash/Murmur3_32HashFunction.java b/android/guava/src/com/google/common/hash/Murmur3_32HashFunction.java
index 373117e9614e..a47184be58b9 100644
--- a/android/guava/src/com/google/common/hash/Murmur3_32HashFunction.java
+++ b/android/guava/src/com/google/common/hash/Murmur3_32HashFunction.java
@@ -39,7 +39,7 @@
 import java.nio.ByteBuffer;
 import java.nio.ByteOrder;
 import java.nio.charset.Charset;
-import org.checkerframework.checker.nullness.compatqual.NullableDecl;
+import javax.annotation.CheckForNull;
 
 /**
  * See MurmurHash3_x86_32 in <a
@@ -51,11 +51,17 @@
  * @author Kurt Alfred Kluever
  */
 @Immutable
+@ElementTypesAreNonnullByDefault
 final class Murmur3_32HashFunction extends AbstractHashFunction implements Serializable {
-  static final HashFunction MURMUR3_32 = new Murmur3_32HashFunction(0);
+  static final HashFunction MURMUR3_32 =
+      new Murmur3_32HashFunction(0, /* supplementaryPlaneFix= */ false);
+  static final HashFunction MURMUR3_32_FIXED =
+      new Murmur3_32HashFunction(0, /* supplementaryPlaneFix= */ true);
 
+  // We can include the non-BMP fix here because Hashing.goodFastHash stresses that the hash is a
+  // temporary-use one. Therefore it shouldn't be persisted.
   static final HashFunction GOOD_FAST_HASH_32 =
-      new Murmur3_32HashFunction(Hashing.GOOD_FAST_HASH_SEED);
+      new Murmur3_32HashFunction(Hashing.GOOD_FAST_HASH_SEED, /* supplementaryPlaneFix= */ true);
 
   private static final int CHUNK_SIZE = 4;
 
@@ -63,9 +69,11 @@ final class Murmur3_32HashFunction extends AbstractHashFunction implements Seria
   private static final int C2 = 0x1b873593;
 
   private final int seed;
+  private final boolean supplementaryPlaneFix;
 
-  Murmur3_32HashFunction(int seed) {
+  Murmur3_32HashFunction(int seed, boolean supplementaryPlaneFix) {
     this.seed = seed;
+    this.supplementaryPlaneFix = supplementaryPlaneFix;
   }
 
   @Override
@@ -84,10 +92,10 @@ public String toString() {
   }
 
   @Override
-  public boolean equals(@NullableDecl Object object) {
+  public boolean equals(@CheckForNull Object object) {
     if (object instanceof Murmur3_32HashFunction) {
       Murmur3_32HashFunction other = (Murmur3_32HashFunction) object;
-      return seed == other.seed;
+      return seed == other.seed && supplementaryPlaneFix == other.supplementaryPlaneFix;
     }
     return false;
   }
@@ -190,6 +198,9 @@ public HashCode hashString(CharSequence input, Charset charset) {
           }
           i++;
           buffer |= codePointToFourUtf8Bytes(codePoint) << shift;
+          if (supplementaryPlaneFix) { // bug compatibility: earlier versions did not have this add
+            shift += 32;
+          }
           len += 4;
         }
 
@@ -391,20 +402,22 @@ public HashCode hash() {
   }
 
   private static long codePointToFourUtf8Bytes(int codePoint) {
-    return (((0xFL << 4) | (codePoint >>> 18)) & 0xFF)
+    // codePoint has at most 21 bits
+    return ((0xFL << 4) | (codePoint >>> 18))
         | ((0x80L | (0x3F & (codePoint >>> 12))) << 8)
         | ((0x80L | (0x3F & (codePoint >>> 6))) << 16)
         | ((0x80L | (0x3F & codePoint)) << 24);
   }
 
   private static long charToThreeUtf8Bytes(char c) {
-    return (((0xF << 5) | (c >>> 12)) & 0xFF)
+    return ((0x7L << 5) | (c >>> 12))
         | ((0x80 | (0x3F & (c >>> 6))) << 8)
         | ((0x80 | (0x3F & c)) << 16);
   }
 
   private static long charToTwoUtf8Bytes(char c) {
-    return (((0xF << 6) | (c >>> 6)) & 0xFF) | ((0x80 | (0x3F & c)) << 8);
+    // c has at most 11 bits
+    return ((0x3L << 6) | (c >>> 6)) | ((0x80 | (0x3F & c)) << 8);
   }
 
   private static final long serialVersionUID = 0L;
diff --git a/android/guava/src/com/google/common/hash/ParametricNullness.java b/android/guava/src/com/google/common/hash/ParametricNullness.java
new file mode 100644
index 000000000000..460106c092ea
--- /dev/null
+++ b/android/guava/src/com/google/common/hash/ParametricNullness.java
@@ -0,0 +1,52 @@
+/*
+ * Copyright (C) 2021 The Guava Authors
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package com.google.common.hash;
+
+import static java.lang.annotation.ElementType.FIELD;
+import static java.lang.annotation.ElementType.METHOD;
+import static java.lang.annotation.ElementType.PARAMETER;
+import static java.lang.annotation.RetentionPolicy.RUNTIME;
+
+import com.google.common.annotations.GwtCompatible;
+import java.lang.annotation.Retention;
+import java.lang.annotation.Target;
+
+/**
+ * Marks a "top-level" type-variable usage as the closest we can get to "non-nullable when
+ * non-nullable; nullable when nullable" (like the Android <a
+ * href="https://android.googlesource.com/platform/libcore/+/master/luni/src/main/java/libcore/util/NullFromTypeParam.java">{@code
+ * NullFromTypeParam}</a>).
+ *
+ * <p>Consumers of this annotation include:
+ *
+ * <ul>
+ *   <li>Kotlin, for which it makes the type-variable usage (a) a Kotlin platform type when the type
+ *       argument is non-nullable and (b) nullable when the type argument is nullable. We use this
+ *       to "undo" {@link ElementTypesAreNonnullByDefault}.
+ *   <li><a href="https://developers.google.com/j2objc">J2ObjC</a>
+ *   <li>{@code NullPointerTester}, at least in the Android backport (where the type-use annotations
+ *       {@code NullPointerTester} would need are not available) and in case of <a
+ *       href="https://bugs.openjdk.java.net/browse/JDK-8202469">JDK-8202469</a>
+ * </ul>
+ *
+ */
+@GwtCompatible
+@Retention(RUNTIME)
+@Target({FIELD, METHOD, PARAMETER})
+@javax.annotation.meta.TypeQualifierNickname
+@javax.annotation.Nonnull(when = javax.annotation.meta.When.UNKNOWN)
+@interface ParametricNullness {}
diff --git a/android/guava/src/com/google/common/hash/PrimitiveSink.java b/android/guava/src/com/google/common/hash/PrimitiveSink.java
index ffeb8fdbca6d..a29ba4e13609 100644
--- a/android/guava/src/com/google/common/hash/PrimitiveSink.java
+++ b/android/guava/src/com/google/common/hash/PrimitiveSink.java
@@ -27,6 +27,7 @@
  */
 @Beta
 @CanIgnoreReturnValue
+@ElementTypesAreNonnullByDefault
 public interface PrimitiveSink {
   /**
    * Puts a byte into this sink.
diff --git a/android/guava/src/com/google/common/hash/SipHashFunction.java b/android/guava/src/com/google/common/hash/SipHashFunction.java
index 546fae274b8c..a226b61a50b9 100644
--- a/android/guava/src/com/google/common/hash/SipHashFunction.java
+++ b/android/guava/src/com/google/common/hash/SipHashFunction.java
@@ -24,7 +24,7 @@
 import com.google.errorprone.annotations.Immutable;
 import java.io.Serializable;
 import java.nio.ByteBuffer;
-import org.checkerframework.checker.nullness.compatqual.NullableDecl;
+import javax.annotation.CheckForNull;
 
 /**
  * {@link HashFunction} implementation of SipHash-c-d.
@@ -34,6 +34,7 @@
  * @author Daniel J. Bernstein
  */
 @Immutable
+@ElementTypesAreNonnullByDefault
 final class SipHashFunction extends AbstractHashFunction implements Serializable {
   static final HashFunction SIP_HASH_24 =
       new SipHashFunction(2, 4, 0x0706050403020100L, 0x0f0e0d0c0b0a0908L);
@@ -81,7 +82,7 @@ public String toString() {
   }
 
   @Override
-  public boolean equals(@NullableDecl Object object) {
+  public boolean equals(@CheckForNull Object object) {
     if (object instanceof SipHashFunction) {
       SipHashFunction other = (SipHashFunction) object;
       return (c == other.c) && (d == other.d) && (k0 == other.k0) && (k1 == other.k1);
diff --git a/android/guava/src/com/google/common/hash/Striped64.java b/android/guava/src/com/google/common/hash/Striped64.java
index 9542bef5a77c..1a0671c9d7c5 100644
--- a/android/guava/src/com/google/common/hash/Striped64.java
+++ b/android/guava/src/com/google/common/hash/Striped64.java
@@ -13,7 +13,8 @@
 
 import com.google.common.annotations.GwtIncompatible;
 import java.util.Random;
-import org.checkerframework.checker.nullness.compatqual.NullableDecl;
+import javax.annotation.CheckForNull;
+import org.checkerframework.checker.nullness.qual.Nullable;
 
 /**
  * A package-local class holding common representation and mechanics for classes supporting dynamic
@@ -21,6 +22,7 @@
  * so.
  */
 @GwtIncompatible
+@ElementTypesAreNonnullByDefault
 abstract class Striped64 extends Number {
   /*
    * This class maintains a lazily-initialized table of atomically
@@ -125,7 +127,7 @@ final boolean cas(long cmp, long val) {
    * class, we use a suboptimal int[] representation to avoid introducing a new type that can impede
    * class-unloading when ThreadLocals are not removed.
    */
-  static final ThreadLocal<int[]> threadHashCode = new ThreadLocal<>();
+  static final ThreadLocal<int @Nullable []> threadHashCode = new ThreadLocal<>();
 
   /** Generator of new random hash codes */
   static final Random rng = new Random();
@@ -134,7 +136,7 @@ final boolean cas(long cmp, long val) {
   static final int NCPU = Runtime.getRuntime().availableProcessors();
 
   /** Table of cells. When non-null, size is a power of 2. */
-  @NullableDecl transient volatile Cell[] cells;
+  @CheckForNull transient volatile Cell[] cells;
 
   /**
    * Base value, used mainly when there is no contention, but also as a fallback during table
@@ -177,7 +179,7 @@ final boolean casBusy() {
    * @param hc the hash code holder
    * @param wasUncontended false if CAS failed before call
    */
-  final void retryUpdate(long x, @NullableDecl int[] hc, boolean wasUncontended) {
+  final void retryUpdate(long x, @CheckForNull int[] hc, boolean wasUncontended) {
     int h;
     if (hc == null) {
       threadHashCode.set(hc = new int[1]); // Initialize randomly
diff --git a/android/guava/src/com/google/common/html/ElementTypesAreNonnullByDefault.java b/android/guava/src/com/google/common/html/ElementTypesAreNonnullByDefault.java
new file mode 100644
index 000000000000..a28b716632d4
--- /dev/null
+++ b/android/guava/src/com/google/common/html/ElementTypesAreNonnullByDefault.java
@@ -0,0 +1,41 @@
+/*
+ * Copyright (C) 2021 The Guava Authors
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package com.google.common.html;
+
+import static java.lang.annotation.ElementType.FIELD;
+import static java.lang.annotation.ElementType.METHOD;
+import static java.lang.annotation.ElementType.PARAMETER;
+import static java.lang.annotation.ElementType.TYPE;
+import static java.lang.annotation.RetentionPolicy.RUNTIME;
+
+import com.google.common.annotations.GwtCompatible;
+import java.lang.annotation.Retention;
+import java.lang.annotation.Target;
+import javax.annotation.Nonnull;
+import javax.annotation.meta.TypeQualifierDefault;
+
+/**
+ * Marks all "top-level" types as non-null in a way that is recognized by Kotlin. Note that this
+ * unfortunately includes type-variable usages, so we also provide {@link ParametricNullness} to
+ * "undo" it as best we can.
+ */
+@GwtCompatible
+@Retention(RUNTIME)
+@Target(TYPE)
+@TypeQualifierDefault({FIELD, METHOD, PARAMETER})
+@Nonnull
+@interface ElementTypesAreNonnullByDefault {}
diff --git a/android/guava/src/com/google/common/html/HtmlEscapers.java b/android/guava/src/com/google/common/html/HtmlEscapers.java
index 29eebe8aaa46..c42638871507 100644
--- a/android/guava/src/com/google/common/html/HtmlEscapers.java
+++ b/android/guava/src/com/google/common/html/HtmlEscapers.java
@@ -35,6 +35,7 @@
  * @since 15.0
  */
 @GwtCompatible
+@ElementTypesAreNonnullByDefault
 public final class HtmlEscapers {
   /**
    * Returns an {@link Escaper} instance that escapes HTML metacharacters as specified by <a
diff --git a/android/guava/src/com/google/common/html/ParametricNullness.java b/android/guava/src/com/google/common/html/ParametricNullness.java
new file mode 100644
index 000000000000..61b44616462b
--- /dev/null
+++ b/android/guava/src/com/google/common/html/ParametricNullness.java
@@ -0,0 +1,52 @@
+/*
+ * Copyright (C) 2021 The Guava Authors
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package com.google.common.html;
+
+import static java.lang.annotation.ElementType.FIELD;
+import static java.lang.annotation.ElementType.METHOD;
+import static java.lang.annotation.ElementType.PARAMETER;
+import static java.lang.annotation.RetentionPolicy.RUNTIME;
+
+import com.google.common.annotations.GwtCompatible;
+import java.lang.annotation.Retention;
+import java.lang.annotation.Target;
+
+/**
+ * Marks a "top-level" type-variable usage as the closest we can get to "non-nullable when
+ * non-nullable; nullable when nullable" (like the Android <a
+ * href="https://android.googlesource.com/platform/libcore/+/master/luni/src/main/java/libcore/util/NullFromTypeParam.java">{@code
+ * NullFromTypeParam}</a>).
+ *
+ * <p>Consumers of this annotation include:
+ *
+ * <ul>
+ *   <li>Kotlin, for which it makes the type-variable usage (a) a Kotlin platform type when the type
+ *       argument is non-nullable and (b) nullable when the type argument is nullable. We use this
+ *       to "undo" {@link ElementTypesAreNonnullByDefault}.
+ *   <li><a href="https://developers.google.com/j2objc">J2ObjC</a>
+ *   <li>{@code NullPointerTester}, at least in the Android backport (where the type-use annotations
+ *       {@code NullPointerTester} would need are not available) and in case of <a
+ *       href="https://bugs.openjdk.java.net/browse/JDK-8202469">JDK-8202469</a>
+ * </ul>
+ *
+ */
+@GwtCompatible
+@Retention(RUNTIME)
+@Target({FIELD, METHOD, PARAMETER})
+@javax.annotation.meta.TypeQualifierNickname
+@javax.annotation.Nonnull(when = javax.annotation.meta.When.UNKNOWN)
+@interface ParametricNullness {}
diff --git a/android/guava/src/com/google/common/io/AppendableWriter.java b/android/guava/src/com/google/common/io/AppendableWriter.java
index 6090bd30da77..d9aab342f29e 100644
--- a/android/guava/src/com/google/common/io/AppendableWriter.java
+++ b/android/guava/src/com/google/common/io/AppendableWriter.java
@@ -21,7 +21,7 @@
 import java.io.Flushable;
 import java.io.IOException;
 import java.io.Writer;
-import org.checkerframework.checker.nullness.compatqual.NullableDecl;
+import javax.annotation.CheckForNull;
 
 /**
  * Writer that places all output on an {@link Appendable} target. If the target is {@link Flushable}
@@ -32,6 +32,7 @@
  * @since 1.0
  */
 @GwtIncompatible
+@ElementTypesAreNonnullByDefault
 class AppendableWriter extends Writer {
   private final Appendable target;
   private boolean closed;
@@ -68,13 +69,15 @@ public void write(int c) throws IOException {
   }
 
   @Override
-  public void write(@NullableDecl String str) throws IOException {
+  public void write(String str) throws IOException {
+    checkNotNull(str);
     checkNotClosed();
     target.append(str);
   }
 
   @Override
-  public void write(@NullableDecl String str, int off, int len) throws IOException {
+  public void write(String str, int off, int len) throws IOException {
+    checkNotNull(str);
     checkNotClosed();
     // tricky: append takes start, end pair...
     target.append(str, off, off + len);
@@ -104,14 +107,14 @@ public Writer append(char c) throws IOException {
   }
 
   @Override
-  public Writer append(@NullableDecl CharSequence charSeq) throws IOException {
+  public Writer append(@CheckForNull CharSequence charSeq) throws IOException {
     checkNotClosed();
     target.append(charSeq);
     return this;
   }
 
   @Override
-  public Writer append(@NullableDecl CharSequence charSeq, int start, int end) throws IOException {
+  public Writer append(@CheckForNull CharSequence charSeq, int start, int end) throws IOException {
     checkNotClosed();
     target.append(charSeq, start, end);
     return this;
diff --git a/android/guava/src/com/google/common/io/BaseEncoding.java b/android/guava/src/com/google/common/io/BaseEncoding.java
index 16e406dedbac..0d6f2e068068 100644
--- a/android/guava/src/com/google/common/io/BaseEncoding.java
+++ b/android/guava/src/com/google/common/io/BaseEncoding.java
@@ -35,7 +35,7 @@
 import java.io.Reader;
 import java.io.Writer;
 import java.util.Arrays;
-import org.checkerframework.checker.nullness.compatqual.NullableDecl;
+import javax.annotation.CheckForNull;
 
 /**
  * A binary encoding scheme for reversibly translating between byte sequences and printable ASCII
@@ -122,6 +122,7 @@
  * @since 14.0
  */
 @GwtCompatible(emulated = true)
+@ElementTypesAreNonnullByDefault
 public abstract class BaseEncoding {
   // TODO(lowasser): consider making encodeTo(Appendable, byte[], int, int) public.
 
@@ -175,7 +176,7 @@ public final String encode(byte[] bytes, int off, int len) {
    * Returns a {@code ByteSink} that writes base-encoded bytes to the specified {@code CharSink}.
    */
   @GwtIncompatible // ByteSink,CharSink
-  public final ByteSink encodingSink(final CharSink encodedSink) {
+  public final ByteSink encodingSink(CharSink encodedSink) {
     checkNotNull(encodedSink);
     return new ByteSink() {
       @Override
@@ -246,7 +247,7 @@ final byte[] decodeChecked(CharSequence chars)
    * CharSource}.
    */
   @GwtIncompatible // ByteSource,CharSource
-  public final ByteSource decodingSource(final CharSource encodedSource) {
+  public final ByteSource decodingSource(CharSource encodedSource) {
     checkNotNull(encodedSource);
     return new ByteSource() {
       @Override
@@ -547,7 +548,7 @@ public String toString() {
     }
 
     @Override
-    public boolean equals(@NullableDecl Object other) {
+    public boolean equals(@CheckForNull Object other) {
       if (other instanceof Alphabet) {
         Alphabet that = (Alphabet) other;
         return Arrays.equals(this.chars, that.chars);
@@ -565,13 +566,13 @@ static class StandardBaseEncoding extends BaseEncoding {
     // TODO(lowasser): provide a useful toString
     final Alphabet alphabet;
 
-    @NullableDecl final Character paddingChar;
+    @CheckForNull final Character paddingChar;
 
-    StandardBaseEncoding(String name, String alphabetChars, @NullableDecl Character paddingChar) {
+    StandardBaseEncoding(String name, String alphabetChars, @CheckForNull Character paddingChar) {
       this(new Alphabet(name, alphabetChars.toCharArray()), paddingChar);
     }
 
-    StandardBaseEncoding(Alphabet alphabet, @NullableDecl Character paddingChar) {
+    StandardBaseEncoding(Alphabet alphabet, @CheckForNull Character paddingChar) {
       this.alphabet = checkNotNull(alphabet);
       checkArgument(
           paddingChar == null || !alphabet.matches(paddingChar),
@@ -587,7 +588,7 @@ int maxEncodedSize(int bytes) {
 
     @GwtIncompatible // Writer,OutputStream
     @Override
-    public OutputStream encodingStream(final Writer out) {
+    public OutputStream encodingStream(Writer out) {
       checkNotNull(out);
       return new OutputStream() {
         int bitBuffer = 0;
@@ -649,7 +650,7 @@ void encodeChunkTo(Appendable target, byte[] bytes, int off, int len) throws IOE
         bitBuffer <<= 8; // Add additional zero byte in the end.
       }
       // Position of first character is length of bitBuffer minus bitsPerChar.
-      final int bitOffset = (len + 1) * 8 - alphabet.bitsPerChar;
+      int bitOffset = (len + 1) * 8 - alphabet.bitsPerChar;
       int bitsProcessed = 0;
       while (bitsProcessed < len * 8) {
         int charIndex = (int) (bitBuffer >>> (bitOffset - bitsProcessed)) & alphabet.mask;
@@ -717,7 +718,7 @@ int decodeTo(byte[] target, CharSequence chars) throws DecodingException {
             chunk |= alphabet.decode(chars.charAt(charIdx + charsProcessed++));
           }
         }
-        final int minOffset = alphabet.bytesPerChunk * 8 - charsProcessed * alphabet.bitsPerChar;
+        int minOffset = alphabet.bytesPerChunk * 8 - charsProcessed * alphabet.bitsPerChar;
         for (int offset = (alphabet.bytesPerChunk - 1) * 8; offset >= minOffset; offset -= 8) {
           target[bytesWritten++] = (byte) ((chunk >>> offset) & 0xFF);
         }
@@ -727,7 +728,7 @@ int decodeTo(byte[] target, CharSequence chars) throws DecodingException {
 
     @Override
     @GwtIncompatible // Reader,InputStream
-    public InputStream decodingStream(final Reader reader) {
+    public InputStream decodingStream(Reader reader) {
       checkNotNull(reader);
       return new InputStream() {
         int bitBuffer = 0;
@@ -829,8 +830,8 @@ public BaseEncoding withSeparator(String separator, int afterEveryChars) {
       return new SeparatedBaseEncoding(this, separator, afterEveryChars);
     }
 
-    @LazyInit @NullableDecl private transient BaseEncoding upperCase;
-    @LazyInit @NullableDecl private transient BaseEncoding lowerCase;
+    @LazyInit @CheckForNull private transient BaseEncoding upperCase;
+    @LazyInit @CheckForNull private transient BaseEncoding lowerCase;
 
     @Override
     public BaseEncoding upperCase() {
@@ -852,7 +853,7 @@ public BaseEncoding lowerCase() {
       return result;
     }
 
-    BaseEncoding newInstance(Alphabet alphabet, @NullableDecl Character paddingChar) {
+    BaseEncoding newInstance(Alphabet alphabet, @CheckForNull Character paddingChar) {
       return new StandardBaseEncoding(alphabet, paddingChar);
     }
 
@@ -871,7 +872,7 @@ public String toString() {
     }
 
     @Override
-    public boolean equals(@NullableDecl Object other) {
+    public boolean equals(@CheckForNull Object other) {
       if (other instanceof StandardBaseEncoding) {
         StandardBaseEncoding that = (StandardBaseEncoding) other;
         return this.alphabet.equals(that.alphabet)
@@ -928,17 +929,17 @@ int decodeTo(byte[] target, CharSequence chars) throws DecodingException {
     }
 
     @Override
-    BaseEncoding newInstance(Alphabet alphabet, @NullableDecl Character paddingChar) {
+    BaseEncoding newInstance(Alphabet alphabet, @CheckForNull Character paddingChar) {
       return new Base16Encoding(alphabet);
     }
   }
 
   static final class Base64Encoding extends StandardBaseEncoding {
-    Base64Encoding(String name, String alphabetChars, @NullableDecl Character paddingChar) {
+    Base64Encoding(String name, String alphabetChars, @CheckForNull Character paddingChar) {
       this(new Alphabet(name, alphabetChars.toCharArray()), paddingChar);
     }
 
-    private Base64Encoding(Alphabet alphabet, @NullableDecl Character paddingChar) {
+    private Base64Encoding(Alphabet alphabet, @CheckForNull Character paddingChar) {
       super(alphabet, paddingChar);
       checkArgument(alphabet.chars.length == 64);
     }
@@ -985,13 +986,13 @@ int decodeTo(byte[] target, CharSequence chars) throws DecodingException {
     }
 
     @Override
-    BaseEncoding newInstance(Alphabet alphabet, @NullableDecl Character paddingChar) {
+    BaseEncoding newInstance(Alphabet alphabet, @CheckForNull Character paddingChar) {
       return new Base64Encoding(alphabet, paddingChar);
     }
   }
 
   @GwtIncompatible
-  static Reader ignoringReader(final Reader delegate, final String toIgnore) {
+  static Reader ignoringReader(Reader delegate, String toIgnore) {
     checkNotNull(delegate);
     checkNotNull(toIgnore);
     return new Reader() {
@@ -1017,7 +1018,7 @@ public void close() throws IOException {
   }
 
   static Appendable separatingAppendable(
-      final Appendable delegate, final String separator, final int afterEveryChars) {
+      Appendable delegate, String separator, int afterEveryChars) {
     checkNotNull(delegate);
     checkNotNull(separator);
     checkArgument(afterEveryChars > 0);
@@ -1036,23 +1037,20 @@ public Appendable append(char c) throws IOException {
       }
 
       @Override
-      public Appendable append(@NullableDecl CharSequence chars, int off, int len)
-          throws IOException {
+      public Appendable append(@CheckForNull CharSequence chars, int off, int len) {
         throw new UnsupportedOperationException();
       }
 
       @Override
-      public Appendable append(@NullableDecl CharSequence chars) throws IOException {
+      public Appendable append(@CheckForNull CharSequence chars) {
         throw new UnsupportedOperationException();
       }
     };
   }
 
   @GwtIncompatible // Writer
-  static Writer separatingWriter(
-      final Writer delegate, final String separator, final int afterEveryChars) {
-    final Appendable separatingAppendable =
-        separatingAppendable(delegate, separator, afterEveryChars);
+  static Writer separatingWriter(Writer delegate, String separator, int afterEveryChars) {
+    Appendable separatingAppendable = separatingAppendable(delegate, separator, afterEveryChars);
     return new Writer() {
       @Override
       public void write(int c) throws IOException {
@@ -1103,7 +1101,7 @@ int maxEncodedSize(int bytes) {
 
     @GwtIncompatible // Writer,OutputStream
     @Override
-    public OutputStream encodingStream(final Writer output) {
+    public OutputStream encodingStream(Writer output) {
       return delegate.encodingStream(separatingWriter(output, separator, afterEveryChars));
     }
 
@@ -1143,7 +1141,7 @@ int decodeTo(byte[] target, CharSequence chars) throws DecodingException {
 
     @Override
     @GwtIncompatible // Reader,InputStream
-    public InputStream decodingStream(final Reader reader) {
+    public InputStream decodingStream(Reader reader) {
       return delegate.decodingStream(ignoringReader(reader, separator));
     }
 
diff --git a/android/guava/src/com/google/common/io/ByteArrayDataInput.java b/android/guava/src/com/google/common/io/ByteArrayDataInput.java
index bef1431e2b23..cf84fcc136b7 100644
--- a/android/guava/src/com/google/common/io/ByteArrayDataInput.java
+++ b/android/guava/src/com/google/common/io/ByteArrayDataInput.java
@@ -18,6 +18,7 @@
 import com.google.errorprone.annotations.CanIgnoreReturnValue;
 import java.io.DataInput;
 import java.io.IOException;
+import javax.annotation.CheckForNull;
 
 /**
  * An extension of {@code DataInput} for reading from in-memory byte arrays; its methods offer
@@ -32,6 +33,7 @@
  * @since 1.0
  */
 @GwtIncompatible
+@ElementTypesAreNonnullByDefault
 public interface ByteArrayDataInput extends DataInput {
   @Override
   void readFully(byte b[]);
@@ -86,6 +88,7 @@ public interface ByteArrayDataInput extends DataInput {
 
   @CanIgnoreReturnValue // to skip a line
   @Override
+  @CheckForNull
   String readLine();
 
   @CanIgnoreReturnValue // to skip a field
diff --git a/android/guava/src/com/google/common/io/ByteArrayDataOutput.java b/android/guava/src/com/google/common/io/ByteArrayDataOutput.java
index e1ad6ab2f5f7..373907361d8c 100644
--- a/android/guava/src/com/google/common/io/ByteArrayDataOutput.java
+++ b/android/guava/src/com/google/common/io/ByteArrayDataOutput.java
@@ -26,6 +26,7 @@
  * @since 1.0
  */
 @GwtIncompatible
+@ElementTypesAreNonnullByDefault
 public interface ByteArrayDataOutput extends DataOutput {
   @Override
   void write(int b);
diff --git a/android/guava/src/com/google/common/io/ByteProcessor.java b/android/guava/src/com/google/common/io/ByteProcessor.java
index 115c73571555..98ea3ffbb27d 100644
--- a/android/guava/src/com/google/common/io/ByteProcessor.java
+++ b/android/guava/src/com/google/common/io/ByteProcessor.java
@@ -19,6 +19,7 @@
 import com.google.errorprone.annotations.CanIgnoreReturnValue;
 import com.google.errorprone.annotations.DoNotMock;
 import java.io.IOException;
+import org.checkerframework.checker.nullness.qual.Nullable;
 
 /**
  * A callback interface to process bytes from a stream.
@@ -32,7 +33,8 @@
 @Beta
 @DoNotMock("Implement it normally")
 @GwtIncompatible
-public interface ByteProcessor<T> {
+@ElementTypesAreNonnullByDefault
+public interface ByteProcessor<T extends @Nullable Object> {
   /**
    * This method will be called for each chunk of bytes in an input stream. The implementation
    * should process the bytes from {@code buf[off]} through {@code buf[off + len - 1]} (inclusive).
@@ -46,5 +48,6 @@ public interface ByteProcessor<T> {
   boolean processBytes(byte[] buf, int off, int len) throws IOException;
 
   /** Return the result of processing all the bytes. */
+  @ParametricNullness
   T getResult();
 }
diff --git a/android/guava/src/com/google/common/io/ByteSink.java b/android/guava/src/com/google/common/io/ByteSink.java
index ffba6e0a928c..7a6af6fc588b 100644
--- a/android/guava/src/com/google/common/io/ByteSink.java
+++ b/android/guava/src/com/google/common/io/ByteSink.java
@@ -46,6 +46,7 @@
  * @author Colin Decker
  */
 @GwtIncompatible
+@ElementTypesAreNonnullByDefault
 public abstract class ByteSink {
 
   /** Constructor for use by subclasses. */
diff --git a/android/guava/src/com/google/common/io/ByteSource.java b/android/guava/src/com/google/common/io/ByteSource.java
index 19f3a43027de..c8da9678b812 100644
--- a/android/guava/src/com/google/common/io/ByteSource.java
+++ b/android/guava/src/com/google/common/io/ByteSource.java
@@ -40,6 +40,7 @@
 import java.util.Arrays;
 import java.util.Collection;
 import java.util.Iterator;
+import org.checkerframework.checker.nullness.qual.Nullable;
 
 /**
  * A readable source of bytes, such as a file. Unlike an {@link InputStream}, a {@code ByteSource}
@@ -57,10 +58,23 @@
  *       doing something and finally closing the stream that was opened.
  * </ul>
  *
+ * <p><b>Note:</b> In general, {@code ByteSource} is intended to be used for "file-like" sources
+ * that provide streams that are:
+ *
+ * <ul>
+ *   <li><b>Finite:</b> Many operations, such as {@link #size()} and {@link #read()}, will either
+ *       block indefinitely or fail if the source creates an infinite stream.
+ *   <li><b>Non-destructive:</b> A <i>destructive</i> stream will consume or otherwise alter the
+ *       bytes of the source as they are read from it. A source that provides such streams will not
+ *       be reusable, and operations that read from the stream (including {@link #size()}, in some
+ *       implementations) will prevent further operations from completing as expected.
+ * </ul>
+ *
  * @since 14.0
  * @author Colin Decker
  */
 @GwtIncompatible
+@ElementTypesAreNonnullByDefault
 public abstract class ByteSource {
 
   /** Constructor for use by subclasses. */
@@ -302,7 +316,7 @@ public byte[] read() throws IOException {
    */
   @Beta
   @CanIgnoreReturnValue // some processors won't return a useful result
-  public <T> T read(ByteProcessor<T> processor) throws IOException {
+  public <T extends @Nullable Object> T read(ByteProcessor<T> processor) throws IOException {
     checkNotNull(processor);
 
     Closer closer = Closer.create();
@@ -416,7 +430,7 @@ public static ByteSource concat(ByteSource... sources) {
    * Returns a view of the given byte array as a {@link ByteSource}. To view only a specific range
    * in the array, use {@code ByteSource.wrap(b).slice(offset, length)}.
    *
-   * <p>Note that the given byte array may be be passed directly to methods on, for example, {@code
+   * <p>Note that the given byte array may be passed directly to methods on, for example, {@code
    * OutputStream} (when {@code copyTo(OutputStream)} is called on the resulting {@code
    * ByteSource}). This could allow a malicious {@code OutputStream} implementation to modify the
    * contents of the array, but provides better performance in the normal case.
@@ -606,7 +620,8 @@ public byte[] read() {
 
     @SuppressWarnings("CheckReturnValue") // it doesn't matter what processBytes returns here
     @Override
-    public <T> T read(ByteProcessor<T> processor) throws IOException {
+    @ParametricNullness
+    public <T extends @Nullable Object> T read(ByteProcessor<T> processor) throws IOException {
       processor.processBytes(bytes, offset, length);
       return processor.getResult();
     }
diff --git a/android/guava/src/com/google/common/io/ByteStreams.java b/android/guava/src/com/google/common/io/ByteStreams.java
index bdb24dbcc7d3..99213bf16bef 100644
--- a/android/guava/src/com/google/common/io/ByteStreams.java
+++ b/android/guava/src/com/google/common/io/ByteStreams.java
@@ -18,6 +18,8 @@
 import static com.google.common.base.Preconditions.checkNotNull;
 import static com.google.common.base.Preconditions.checkPositionIndex;
 import static com.google.common.base.Preconditions.checkPositionIndexes;
+import static java.lang.Math.max;
+import static java.lang.Math.min;
 
 import com.google.common.annotations.Beta;
 import com.google.common.annotations.GwtIncompatible;
@@ -41,6 +43,8 @@
 import java.util.ArrayDeque;
 import java.util.Arrays;
 import java.util.Queue;
+import javax.annotation.CheckForNull;
+import org.checkerframework.checker.nullness.qual.Nullable;
 
 /**
  * Provides utility methods for working with byte arrays and I/O streams.
@@ -50,6 +54,7 @@
  * @since 1.0
  */
 @GwtIncompatible
+@ElementTypesAreNonnullByDefault
 public final class ByteStreams {
 
   private static final int BUFFER_SIZE = 8192;
@@ -167,13 +172,18 @@ public static long copy(ReadableByteChannel from, WritableByteChannel to) throws
    */
   private static byte[] toByteArrayInternal(InputStream in, Queue<byte[]> bufs, int totalLen)
       throws IOException {
-    // Starting with an 8k buffer, double the size of each successive buffer. Buffers are retained
-    // in a deque so that there's no copying between buffers while reading and so all of the bytes
-    // in each new allocated buffer are available for reading from the stream.
-    for (int bufSize = BUFFER_SIZE;
+    // Roughly size to match what has been read already. Some file systems, such as procfs, return 0
+    // as their length. These files are very small, so it's wasteful to allocate an 8KB buffer.
+    int initialBufferSize = min(BUFFER_SIZE, max(128, Integer.highestOneBit(totalLen) * 2));
+    // Starting with an 8k buffer, double the size of each successive buffer. Smaller buffers
+    // quadruple in size until they reach 8k, to minimize the number of small reads for longer
+    // streams. Buffers are retained in a deque so that there's no copying between buffers while
+    // reading and so all of the bytes in each new allocated buffer are available for reading from
+    // the stream.
+    for (int bufSize = initialBufferSize;
         totalLen < MAX_ARRAY_LEN;
-        bufSize = IntMath.saturatedMultiply(bufSize, 2)) {
-      byte[] buf = new byte[Math.min(bufSize, MAX_ARRAY_LEN - totalLen)];
+        bufSize = IntMath.saturatedMultiply(bufSize, bufSize < 4096 ? 4 : 2)) {
+      byte[] buf = new byte[min(bufSize, MAX_ARRAY_LEN - totalLen)];
       bufs.add(buf);
       int off = 0;
       while (off < buf.length) {
@@ -197,11 +207,18 @@ private static byte[] toByteArrayInternal(InputStream in, Queue<byte[]> bufs, in
   }
 
   private static byte[] combineBuffers(Queue<byte[]> bufs, int totalLen) {
-    byte[] result = new byte[totalLen];
-    int remaining = totalLen;
+    if (bufs.isEmpty()) {
+      return new byte[0];
+    }
+    byte[] result = bufs.remove();
+    if (result.length == totalLen) {
+      return result;
+    }
+    int remaining = totalLen - result.length;
+    result = Arrays.copyOf(result, totalLen);
     while (remaining > 0) {
       byte[] buf = bufs.remove();
-      int bytesToCopy = Math.min(remaining, buf.length);
+      int bytesToCopy = min(remaining, buf.length);
       int resultOffset = totalLen - remaining;
       System.arraycopy(buf, 0, result, resultOffset, bytesToCopy);
       remaining -= bytesToCopy;
@@ -253,7 +270,7 @@ static byte[] toByteArray(InputStream in, long expectedSize) throws IOException
     }
 
     // the stream was longer, so read the rest normally
-    Queue<byte[]> bufs = new ArrayDeque<byte[]>(TO_BYTE_ARRAY_DEQUE_SIZE + 2);
+    Queue<byte[]> bufs = new ArrayDeque<>(TO_BYTE_ARRAY_DEQUE_SIZE + 2);
     bufs.add(bytes);
     bufs.add(new byte[] {(byte) b});
     return toByteArrayInternal(in, bufs, bytes.length + 1);
@@ -438,6 +455,7 @@ public double readDouble() {
     }
 
     @Override
+    @CheckForNull
     public String readLine() {
       try {
         return input.readLine();
@@ -653,6 +671,7 @@ public void write(byte[] b) {
         @Override
         public void write(byte[] b, int off, int len) {
           checkNotNull(b);
+          checkPositionIndexes(off, off + len, b.length);
         }
 
         @Override
@@ -815,7 +834,7 @@ public static void skipFully(InputStream in, long n) throws IOException {
    * either the full amount has been skipped or until the end of the stream is reached, whichever
    * happens first. Returns the total number of bytes skipped.
    */
-  static long skipUpTo(InputStream in, final long n) throws IOException {
+  static long skipUpTo(InputStream in, long n) throws IOException {
     long totalSkipped = 0;
     // A buffer is allocated if skipSafely does not skip any bytes.
     byte[] buf = null;
@@ -869,7 +888,9 @@ private static long skipSafely(InputStream in, long n) throws IOException {
    */
   @Beta
   @CanIgnoreReturnValue // some processors won't return a useful result
-  public static <T> T readBytes(InputStream input, ByteProcessor<T> processor) throws IOException {
+  @ParametricNullness
+  public static <T extends @Nullable Object> T readBytes(
+      InputStream input, ByteProcessor<T> processor) throws IOException {
     checkNotNull(input);
     checkNotNull(processor);
 
diff --git a/android/guava/src/com/google/common/io/CharSequenceReader.java b/android/guava/src/com/google/common/io/CharSequenceReader.java
index 4cbeda1fb365..790e26623625 100644
--- a/android/guava/src/com/google/common/io/CharSequenceReader.java
+++ b/android/guava/src/com/google/common/io/CharSequenceReader.java
@@ -17,11 +17,13 @@
 import static com.google.common.base.Preconditions.checkArgument;
 import static com.google.common.base.Preconditions.checkNotNull;
 import static com.google.common.base.Preconditions.checkPositionIndexes;
+import static java.util.Objects.requireNonNull;
 
 import com.google.common.annotations.GwtIncompatible;
 import java.io.IOException;
 import java.io.Reader;
 import java.nio.CharBuffer;
+import javax.annotation.CheckForNull;
 
 /**
  * A {@link Reader} that reads the characters in a {@link CharSequence}. Like {@code StringReader},
@@ -31,9 +33,10 @@
  */
 // TODO(cgdecker): make this public? as a type, or a method in CharStreams?
 @GwtIncompatible
+@ElementTypesAreNonnullByDefault
 final class CharSequenceReader extends Reader {
 
-  private CharSequence seq;
+  @CheckForNull private CharSequence seq;
   private int pos;
   private int mark;
 
@@ -53,13 +56,27 @@ private boolean hasRemaining() {
   }
 
   private int remaining() {
+    requireNonNull(seq); // safe as long as we call this only after checkOpen
     return seq.length() - pos;
   }
 
+  /*
+   * To avoid the need to call requireNonNull so much, we could consider more clever approaches,
+   * such as:
+   *
+   * - Make checkOpen return the non-null `seq`. Then callers can assign that to a local variable or
+   *   even back to `this.seq`. However, that may suggest that we're defending against concurrent
+   *   mutation, which is not an actual risk because we use `synchronized`.
+   * - Make `remaining` require a non-null `seq` argument. But this is a bit weird because the
+   *   method, while it would avoid the instance field `seq` would still access the instance field
+   *   `pos`.
+   */
+
   @Override
   public synchronized int read(CharBuffer target) throws IOException {
     checkNotNull(target);
     checkOpen();
+    requireNonNull(seq); // safe because of checkOpen
     if (!hasRemaining()) {
       return -1;
     }
@@ -73,6 +90,7 @@ public synchronized int read(CharBuffer target) throws IOException {
   @Override
   public synchronized int read() throws IOException {
     checkOpen();
+    requireNonNull(seq); // safe because of checkOpen
     return hasRemaining() ? seq.charAt(pos++) : -1;
   }
 
@@ -80,6 +98,7 @@ public synchronized int read() throws IOException {
   public synchronized int read(char[] cbuf, int off, int len) throws IOException {
     checkPositionIndexes(off, off + len, cbuf.length);
     checkOpen();
+    requireNonNull(seq); // safe because of checkOpen
     if (!hasRemaining()) {
       return -1;
     }
diff --git a/android/guava/src/com/google/common/io/CharSink.java b/android/guava/src/com/google/common/io/CharSink.java
index e615662d336d..bdf5f38c3c32 100644
--- a/android/guava/src/com/google/common/io/CharSink.java
+++ b/android/guava/src/com/google/common/io/CharSink.java
@@ -48,6 +48,7 @@
  * @author Colin Decker
  */
 @GwtIncompatible
+@ElementTypesAreNonnullByDefault
 public abstract class CharSink {
 
   /** Constructor for use by subclasses. */
diff --git a/android/guava/src/com/google/common/io/CharSource.java b/android/guava/src/com/google/common/io/CharSource.java
index 82110dac7d46..b7623ff62176 100644
--- a/android/guava/src/com/google/common/io/CharSource.java
+++ b/android/guava/src/com/google/common/io/CharSource.java
@@ -34,7 +34,8 @@
 import java.nio.charset.Charset;
 import java.util.Iterator;
 import java.util.List;
-import org.checkerframework.checker.nullness.compatqual.NullableDecl;
+import javax.annotation.CheckForNull;
+import org.checkerframework.checker.nullness.qual.Nullable;
 
 /**
  * A readable source of characters, such as a text file. Unlike a {@link Reader}, a {@code
@@ -60,10 +61,23 @@
  * <p>Any {@link ByteSource} containing text encoded with a specific {@linkplain Charset character
  * encoding} may be viewed as a {@code CharSource} using {@link ByteSource#asCharSource(Charset)}.
  *
+ * <p><b>Note:</b> In general, {@code CharSource} is intended to be used for "file-like" sources
+ * that provide readers that are:
+ *
+ * <ul>
+ *   <li><b>Finite:</b> Many operations, such as {@link #length()} and {@link #read()}, will either
+ *       block indefinitely or fail if the source creates an infinite reader.
+ *   <li><b>Non-destructive:</b> A <i>destructive</i> reader will consume or otherwise alter the
+ *       source as they are read from it. A source that provides such readers will not be reusable,
+ *       and operations that read from the stream (including {@link #length()}, in some
+ *       implementations) will prevent further operations from completing as expected.
+ * </ul>
+ *
  * @since 14.0
  * @author Colin Decker
  */
 @GwtIncompatible
+@ElementTypesAreNonnullByDefault
 public abstract class CharSource {
 
   /** Constructor for use by subclasses. */
@@ -248,7 +262,7 @@ public String read() throws IOException {
    *
    * @throws IOException if an I/O error occurs while reading from this source
    */
-  @NullableDecl
+  @CheckForNull
   public String readFirstLine() throws IOException {
     Closer closer = Closer.create();
     try {
@@ -305,7 +319,8 @@ public ImmutableList<String> readLines() throws IOException {
    */
   @Beta
   @CanIgnoreReturnValue // some processors won't return a useful result
-  public <T> T readLines(LineProcessor<T> processor) throws IOException {
+  @ParametricNullness
+  public <T extends @Nullable Object> T readLines(LineProcessor<T> processor) throws IOException {
     checkNotNull(processor);
 
     Closer closer = Closer.create();
@@ -494,6 +509,7 @@ private Iterator<String> linesIterator() {
         Iterator<String> lines = LINE_SPLITTER.split(seq).iterator();
 
         @Override
+        @CheckForNull
         protected String computeNext() {
           if (lines.hasNext()) {
             String next = lines.next();
@@ -508,6 +524,7 @@ protected String computeNext() {
     }
 
     @Override
+    @CheckForNull
     public String readFirstLine() {
       Iterator<String> lines = linesIterator();
       return lines.hasNext() ? lines.next() : null;
@@ -519,7 +536,8 @@ public ImmutableList<String> readLines() {
     }
 
     @Override
-    public <T> T readLines(LineProcessor<T> processor) throws IOException {
+    @ParametricNullness
+    public <T extends @Nullable Object> T readLines(LineProcessor<T> processor) throws IOException {
       Iterator<String> lines = linesIterator();
       while (lines.hasNext()) {
         if (!processor.processLine(lines.next())) {
diff --git a/android/guava/src/com/google/common/io/CharStreams.java b/android/guava/src/com/google/common/io/CharStreams.java
index c700691b1c11..d36f9a3c5cd6 100644
--- a/android/guava/src/com/google/common/io/CharStreams.java
+++ b/android/guava/src/com/google/common/io/CharStreams.java
@@ -28,13 +28,12 @@
 import java.nio.CharBuffer;
 import java.util.ArrayList;
 import java.util.List;
-import org.checkerframework.checker.nullness.compatqual.NullableDecl;
+import javax.annotation.CheckForNull;
+import org.checkerframework.checker.nullness.qual.Nullable;
 
 /**
  * Provides utility methods for working with character streams.
  *
- * <p>All method parameters must be non-null unless documented otherwise.
- *
  * <p>Some of the methods in this class take arguments with a generic type of {@code Readable &
  * Closeable}. A {@link java.io.Reader} implements both of those interfaces. Similarly for {@code
  * Appendable & Closeable} and {@link java.io.Writer}.
@@ -45,6 +44,7 @@
  * @since 1.0
  */
 @GwtIncompatible
+@ElementTypesAreNonnullByDefault
 public final class CharStreams {
 
   // 2K chars (4K bytes)
@@ -215,7 +215,9 @@ public static List<String> readLines(Readable r) throws IOException {
    */
   @Beta
   @CanIgnoreReturnValue // some processors won't return a useful result
-  public static <T> T readLines(Readable readable, LineProcessor<T> processor) throws IOException {
+  @ParametricNullness
+  public static <T extends @Nullable Object> T readLines(
+      Readable readable, LineProcessor<T> processor) throws IOException {
     checkNotNull(readable);
     checkNotNull(processor);
 
@@ -307,12 +309,12 @@ public void write(String str, int off, int len) {
     }
 
     @Override
-    public Writer append(@NullableDecl CharSequence csq) {
+    public Writer append(@CheckForNull CharSequence csq) {
       return this;
     }
 
     @Override
-    public Writer append(@NullableDecl CharSequence csq, int start, int end) {
+    public Writer append(@CheckForNull CharSequence csq, int start, int end) {
       checkPositionIndexes(start, end, csq == null ? "null".length() : csq.length());
       return this;
     }
diff --git a/android/guava/src/com/google/common/io/Closeables.java b/android/guava/src/com/google/common/io/Closeables.java
index e7489a7b3091..b45f5f0fde65 100644
--- a/android/guava/src/com/google/common/io/Closeables.java
+++ b/android/guava/src/com/google/common/io/Closeables.java
@@ -23,7 +23,7 @@
 import java.io.Reader;
 import java.util.logging.Level;
 import java.util.logging.Logger;
-import org.checkerframework.checker.nullness.compatqual.NullableDecl;
+import javax.annotation.CheckForNull;
 
 /**
  * Utility methods for working with {@link Closeable} objects.
@@ -33,6 +33,7 @@
  */
 @Beta
 @GwtIncompatible
+@ElementTypesAreNonnullByDefault
 public final class Closeables {
   @VisibleForTesting static final Logger logger = Logger.getLogger(Closeables.class.getName());
 
@@ -69,7 +70,7 @@ private Closeables() {}
    * @throws IOException if {@code swallowIOException} is false and {@code close} throws an {@code
    *     IOException}.
    */
-  public static void close(@NullableDecl Closeable closeable, boolean swallowIOException)
+  public static void close(@CheckForNull Closeable closeable, boolean swallowIOException)
       throws IOException {
     if (closeable == null) {
       return;
@@ -99,7 +100,7 @@ public static void close(@NullableDecl Closeable closeable, boolean swallowIOExc
    *     does nothing
    * @since 17.0
    */
-  public static void closeQuietly(@NullableDecl InputStream inputStream) {
+  public static void closeQuietly(@CheckForNull InputStream inputStream) {
     try {
       close(inputStream, true);
     } catch (IOException impossible) {
@@ -120,7 +121,7 @@ public static void closeQuietly(@NullableDecl InputStream inputStream) {
    * @param reader the reader to be closed, or {@code null} in which case this method does nothing
    * @since 17.0
    */
-  public static void closeQuietly(@NullableDecl Reader reader) {
+  public static void closeQuietly(@CheckForNull Reader reader) {
     try {
       close(reader, true);
     } catch (IOException impossible) {
diff --git a/android/guava/src/com/google/common/io/Closer.java b/android/guava/src/com/google/common/io/Closer.java
index ff5db89b233e..12998eff95bb 100644
--- a/android/guava/src/com/google/common/io/Closer.java
+++ b/android/guava/src/com/google/common/io/Closer.java
@@ -27,7 +27,8 @@
 import java.util.ArrayDeque;
 import java.util.Deque;
 import java.util.logging.Level;
-import org.checkerframework.checker.nullness.compatqual.NullableDecl;
+import javax.annotation.CheckForNull;
+import org.checkerframework.checker.nullness.qual.Nullable;
 
 /**
  * A {@link Closeable} that collects {@code Closeable} resources and closes them all when it is
@@ -88,13 +89,16 @@
 // Coffee's for {@link Closer closers} only.
 @Beta
 @GwtIncompatible
+@ElementTypesAreNonnullByDefault
 public final class Closer implements Closeable {
 
   /** The suppressor implementation to use for the current Java version. */
-  private static final Suppressor SUPPRESSOR =
-      SuppressingSuppressor.isAvailable()
-          ? SuppressingSuppressor.INSTANCE
-          : LoggingSuppressor.INSTANCE;
+  private static final Suppressor SUPPRESSOR;
+
+  static {
+    SuppressingSuppressor suppressingSuppressor = SuppressingSuppressor.tryCreate();
+    SUPPRESSOR = suppressingSuppressor == null ? LoggingSuppressor.INSTANCE : suppressingSuppressor;
+  }
 
   /** Creates a new {@link Closer}. */
   public static Closer create() {
@@ -105,7 +109,7 @@ public static Closer create() {
 
   // only need space for 2 elements in most cases, so try to use the smallest array possible
   private final Deque<Closeable> stack = new ArrayDeque<>(4);
-  @NullableDecl private Throwable thrown;
+  @CheckForNull private Throwable thrown;
 
   @VisibleForTesting
   Closer(Suppressor suppressor) {
@@ -120,7 +124,8 @@ public static Closer create() {
    */
   // close. this word no longer has any meaning to me.
   @CanIgnoreReturnValue
-  public <C extends Closeable> C register(@NullableDecl C closeable) {
+  @ParametricNullness
+  public <C extends @Nullable Closeable> C register(@ParametricNullness C closeable) {
     if (closeable != null) {
       stack.addFirst(closeable);
     }
@@ -257,21 +262,21 @@ public void suppress(Closeable closeable, Throwable thrown, Throwable suppressed
    */
   @VisibleForTesting
   static final class SuppressingSuppressor implements Suppressor {
-
-    static final SuppressingSuppressor INSTANCE = new SuppressingSuppressor();
-
-    static boolean isAvailable() {
-      return addSuppressed != null;
-    }
-
-    static final Method addSuppressed = addSuppressedMethodOrNull();
-
-    private static Method addSuppressedMethodOrNull() {
+    @CheckForNull
+    static SuppressingSuppressor tryCreate() {
+      Method addSuppressed;
       try {
-        return Throwable.class.getMethod("addSuppressed", Throwable.class);
+        addSuppressed = Throwable.class.getMethod("addSuppressed", Throwable.class);
       } catch (Throwable e) {
         return null;
       }
+      return new SuppressingSuppressor(addSuppressed);
+    }
+
+    private final Method addSuppressed;
+
+    private SuppressingSuppressor(Method addSuppressed) {
+      this.addSuppressed = addSuppressed;
     }
 
     @Override
diff --git a/android/guava/src/com/google/common/io/CountingInputStream.java b/android/guava/src/com/google/common/io/CountingInputStream.java
index b015aca4bf01..a37807ae7341 100644
--- a/android/guava/src/com/google/common/io/CountingInputStream.java
+++ b/android/guava/src/com/google/common/io/CountingInputStream.java
@@ -30,6 +30,7 @@
  */
 @Beta
 @GwtIncompatible
+@ElementTypesAreNonnullByDefault
 public final class CountingInputStream extends FilterInputStream {
 
   private long count;
diff --git a/android/guava/src/com/google/common/io/CountingOutputStream.java b/android/guava/src/com/google/common/io/CountingOutputStream.java
index 5d67a093dd23..cf62b9c377a4 100644
--- a/android/guava/src/com/google/common/io/CountingOutputStream.java
+++ b/android/guava/src/com/google/common/io/CountingOutputStream.java
@@ -28,6 +28,7 @@
  * @since 1.0
  */
 @GwtIncompatible
+@ElementTypesAreNonnullByDefault
 public final class CountingOutputStream extends FilterOutputStream {
 
   private long count;
diff --git a/android/guava/src/com/google/common/io/ElementTypesAreNonnullByDefault.java b/android/guava/src/com/google/common/io/ElementTypesAreNonnullByDefault.java
new file mode 100644
index 000000000000..48bc10f192a1
--- /dev/null
+++ b/android/guava/src/com/google/common/io/ElementTypesAreNonnullByDefault.java
@@ -0,0 +1,41 @@
+/*
+ * Copyright (C) 2021 The Guava Authors
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package com.google.common.io;
+
+import static java.lang.annotation.ElementType.FIELD;
+import static java.lang.annotation.ElementType.METHOD;
+import static java.lang.annotation.ElementType.PARAMETER;
+import static java.lang.annotation.ElementType.TYPE;
+import static java.lang.annotation.RetentionPolicy.RUNTIME;
+
+import com.google.common.annotations.GwtCompatible;
+import java.lang.annotation.Retention;
+import java.lang.annotation.Target;
+import javax.annotation.Nonnull;
+import javax.annotation.meta.TypeQualifierDefault;
+
+/**
+ * Marks all "top-level" types as non-null in a way that is recognized by Kotlin. Note that this
+ * unfortunately includes type-variable usages, so we also provide {@link ParametricNullness} to
+ * "undo" it as best we can.
+ */
+@GwtCompatible
+@Retention(RUNTIME)
+@Target(TYPE)
+@TypeQualifierDefault({FIELD, METHOD, PARAMETER})
+@Nonnull
+@interface ElementTypesAreNonnullByDefault {}
diff --git a/android/guava/src/com/google/common/io/FileBackedOutputStream.java b/android/guava/src/com/google/common/io/FileBackedOutputStream.java
index d8c4189546fe..9912e2fcd19c 100644
--- a/android/guava/src/com/google/common/io/FileBackedOutputStream.java
+++ b/android/guava/src/com/google/common/io/FileBackedOutputStream.java
@@ -14,6 +14,7 @@
 
 package com.google.common.io;
 
+import static java.util.Objects.requireNonNull;
 
 import com.google.common.annotations.Beta;
 import com.google.common.annotations.GwtIncompatible;
@@ -27,7 +28,7 @@
 import java.io.IOException;
 import java.io.InputStream;
 import java.io.OutputStream;
-import org.checkerframework.checker.nullness.compatqual.NullableDecl;
+import javax.annotation.CheckForNull;
 
 /**
  * An {@link OutputStream} that starts buffering to a byte array, but switches to file buffering
@@ -51,20 +52,22 @@
  */
 @Beta
 @GwtIncompatible
+@ElementTypesAreNonnullByDefault
 public final class FileBackedOutputStream extends OutputStream {
   private final int fileThreshold;
   private final boolean resetOnFinalize;
   private final ByteSource source;
-  @NullableDecl private final File parentDirectory;
+  @CheckForNull private final File parentDirectory;
 
   @GuardedBy("this")
   private OutputStream out;
 
   @GuardedBy("this")
+  @CheckForNull
   private MemoryOutput memory;
 
   @GuardedBy("this")
-  @NullableDecl
+  @CheckForNull
   private File file;
 
   /** ByteArrayOutputStream that exposes its internals. */
@@ -80,6 +83,7 @@ int getCount() {
 
   /** Returns the file holding the data (possibly null). */
   @VisibleForTesting
+  @CheckForNull
   synchronized File getFile() {
     return file;
   }
@@ -107,7 +111,7 @@ public FileBackedOutputStream(int fileThreshold, boolean resetOnFinalize) {
   }
 
   private FileBackedOutputStream(
-      int fileThreshold, boolean resetOnFinalize, @NullableDecl File parentDirectory) {
+      int fileThreshold, boolean resetOnFinalize, @CheckForNull File parentDirectory) {
     this.fileThreshold = fileThreshold;
     this.resetOnFinalize = resetOnFinalize;
     this.parentDirectory = parentDirectory;
@@ -155,6 +159,8 @@ private synchronized InputStream openInputStream() throws IOException {
     if (file != null) {
       return new FileInputStream(file);
     } else {
+      // requireNonNull is safe because we always have either `file` or `memory`.
+      requireNonNull(memory);
       return new ByteArrayInputStream(memory.getBuffer(), 0, memory.getCount());
     }
   }
@@ -218,19 +224,24 @@ public synchronized void flush() throws IOException {
    */
   @GuardedBy("this")
   private void update(int len) throws IOException {
-    if (file == null && (memory.getCount() + len > fileThreshold)) {
+    if (memory != null && (memory.getCount() + len > fileThreshold)) {
       File temp = File.createTempFile("FileBackedOutputStream", null, parentDirectory);
       if (resetOnFinalize) {
         // Finalizers are not guaranteed to be called on system shutdown;
         // this is insurance.
         temp.deleteOnExit();
       }
-      FileOutputStream transfer = new FileOutputStream(temp);
-      transfer.write(memory.getBuffer(), 0, memory.getCount());
-      transfer.flush();
+      try {
+        FileOutputStream transfer = new FileOutputStream(temp);
+        transfer.write(memory.getBuffer(), 0, memory.getCount());
+        transfer.flush();
+        // We've successfully transferred the data; switch to writing to file
+        out = transfer;
+      } catch (IOException e) {
+        temp.delete();
+        throw e;
+      }
 
-      // We've successfully transferred the data; switch to writing to file
-      out = transfer;
       file = temp;
       memory = null;
     }
diff --git a/android/guava/src/com/google/common/io/FileWriteMode.java b/android/guava/src/com/google/common/io/FileWriteMode.java
index 2c69a2edb63b..86872d1badb2 100644
--- a/android/guava/src/com/google/common/io/FileWriteMode.java
+++ b/android/guava/src/com/google/common/io/FileWriteMode.java
@@ -23,6 +23,7 @@
  * @author Colin Decker
  */
 @GwtIncompatible
+@ElementTypesAreNonnullByDefault
 public enum FileWriteMode {
   /** Specifies that writes to the opened file should append to the end of the file. */
   APPEND
diff --git a/android/guava/src/com/google/common/io/Files.java b/android/guava/src/com/google/common/io/Files.java
index 73eb656602df..ba5528ff81dd 100644
--- a/android/guava/src/com/google/common/io/Files.java
+++ b/android/guava/src/com/google/common/io/Files.java
@@ -32,6 +32,7 @@
 import com.google.common.hash.HashCode;
 import com.google.common.hash.HashFunction;
 import com.google.errorprone.annotations.CanIgnoreReturnValue;
+import com.google.errorprone.annotations.InlineMe;
 import java.io.BufferedReader;
 import java.io.BufferedWriter;
 import java.io.File;
@@ -52,6 +53,8 @@
 import java.util.Arrays;
 import java.util.Collections;
 import java.util.List;
+import javax.annotation.CheckForNull;
+import org.checkerframework.checker.nullness.qual.Nullable;
 
 /**
  * Provides utility methods for working with {@linkplain File files}.
@@ -64,6 +67,7 @@
  * @since 1.0
  */
 @GwtIncompatible
+@ElementTypesAreNonnullByDefault
 public final class Files {
 
   /** Maximum loop count when creating temp directories. */
@@ -82,7 +86,6 @@ private Files() {}
    *     helpful predefined constants
    * @return the buffered reader
    */
-  @Beta
   public static BufferedReader newReader(File file, Charset charset) throws FileNotFoundException {
     checkNotNull(file);
     checkNotNull(charset);
@@ -101,7 +104,6 @@ public static BufferedReader newReader(File file, Charset charset) throws FileNo
    *     helpful predefined constants
    * @return the buffered writer
    */
-  @Beta
   public static BufferedWriter newWriter(File file, Charset charset) throws FileNotFoundException {
     checkNotNull(file);
     checkNotNull(charset);
@@ -232,7 +234,6 @@ public static CharSink asCharSink(File file, Charset charset, FileWriteMode... m
    *     (2^31 - 1)
    * @throws IOException if an I/O error occurs
    */
-  @Beta
   public static byte[] toByteArray(File file) throws IOException {
     return asByteSource(file).read();
   }
@@ -245,11 +246,12 @@ public static byte[] toByteArray(File file) throws IOException {
    *     helpful predefined constants
    * @return a string containing all the characters from the file
    * @throws IOException if an I/O error occurs
-   * @deprecated Prefer {@code asCharSource(file, charset).read()}. This method is scheduled to be
-   *     removed in October 2019.
+   * @deprecated Prefer {@code asCharSource(file, charset).read()}.
    */
-  @Beta
   @Deprecated
+  @InlineMe(
+      replacement = "Files.asCharSource(file, charset).read()",
+      imports = "com.google.common.io.Files")
   public static String toString(File file, Charset charset) throws IOException {
     return asCharSource(file, charset).read();
   }
@@ -264,7 +266,6 @@ public static String toString(File file, Charset charset) throws IOException {
    * @param to the destination file
    * @throws IOException if an I/O error occurs
    */
-  @Beta
   public static void write(byte[] from, File to) throws IOException {
     asByteSink(to).write(from);
   }
@@ -277,11 +278,12 @@ public static void write(byte[] from, File to) throws IOException {
    * @param charset the charset used to encode the output stream; see {@link StandardCharsets} for
    *     helpful predefined constants
    * @throws IOException if an I/O error occurs
-   * @deprecated Prefer {@code asCharSink(to, charset).write(from)}. This method is scheduled to be
-   *     removed in October 2019.
+   * @deprecated Prefer {@code asCharSink(to, charset).write(from)}.
    */
-  @Beta
   @Deprecated
+  @InlineMe(
+      replacement = "Files.asCharSink(to, charset).write(from)",
+      imports = "com.google.common.io.Files")
   public static void write(CharSequence from, File to, Charset charset) throws IOException {
     asCharSink(to, charset).write(from);
   }
@@ -296,7 +298,6 @@ public static void write(CharSequence from, File to, Charset charset) throws IOE
    * @param to the output stream
    * @throws IOException if an I/O error occurs
    */
-  @Beta
   public static void copy(File from, OutputStream to) throws IOException {
     asByteSource(from).copyTo(to);
   }
@@ -320,7 +321,6 @@ public static void copy(File from, OutputStream to) throws IOException {
    * @throws IOException if an I/O error occurs
    * @throws IllegalArgumentException if {@code from.equals(to)}
    */
-  @Beta
   public static void copy(File from, File to) throws IOException {
     checkArgument(!from.equals(to), "Source %s and destination %s must be different", from, to);
     asByteSource(from).copyTo(asByteSink(to));
@@ -334,11 +334,12 @@ public static void copy(File from, File to) throws IOException {
    *     helpful predefined constants
    * @param to the appendable object
    * @throws IOException if an I/O error occurs
-   * @deprecated Prefer {@code asCharSource(from, charset).copyTo(to)}. This method is scheduled to
-   *     be removed in October 2019.
+   * @deprecated Prefer {@code asCharSource(from, charset).copyTo(to)}.
    */
-  @Beta
   @Deprecated
+  @InlineMe(
+      replacement = "Files.asCharSource(from, charset).copyTo(to)",
+      imports = "com.google.common.io.Files")
   public
   static void copy(File from, Charset charset, Appendable to) throws IOException {
     asCharSource(from, charset).copyTo(to);
@@ -355,8 +356,10 @@ static void copy(File from, Charset charset, Appendable to) throws IOException {
    * @deprecated Prefer {@code asCharSink(to, charset, FileWriteMode.APPEND).write(from)}. This
    *     method is scheduled to be removed in October 2019.
    */
-  @Beta
   @Deprecated
+  @InlineMe(
+      replacement = "Files.asCharSink(to, charset, FileWriteMode.APPEND).write(from)",
+      imports = {"com.google.common.io.FileWriteMode", "com.google.common.io.Files"})
   public
   static void append(CharSequence from, File to, Charset charset) throws IOException {
     asCharSink(to, charset, FileWriteMode.APPEND).write(from);
@@ -367,7 +370,6 @@ static void append(CharSequence from, File to, Charset charset) throws IOExcepti
    *
    * @throws IOException if an I/O error occurs
    */
-  @Beta
   public static boolean equal(File file1, File file2) throws IOException {
     checkNotNull(file1);
     checkNotNull(file2);
@@ -449,7 +451,6 @@ public static File createTempDir() {
    * @param file the file to create or update
    * @throws IOException if an I/O error occurs
    */
-  @Beta
   @SuppressWarnings("GoodTime") // reading system time without TimeSource
   public static void touch(File file) throws IOException {
     checkNotNull(file);
@@ -467,7 +468,6 @@ public static void touch(File file) throws IOException {
    *     directories of the specified file could not be created.
    * @since 4.0
    */
-  @Beta
   public static void createParentDirs(File file) throws IOException {
     checkNotNull(file);
     File parent = file.getCanonicalFile().getParentFile();
@@ -498,7 +498,6 @@ public static void createParentDirs(File file) throws IOException {
    * @throws IOException if an I/O error occurs
    * @throws IllegalArgumentException if {@code from.equals(to)}
    */
-  @Beta
   public static void move(File from, File to) throws IOException {
     checkNotNull(from);
     checkNotNull(to);
@@ -524,11 +523,13 @@ public static void move(File from, File to) throws IOException {
    *     helpful predefined constants
    * @return the first line, or null if the file is empty
    * @throws IOException if an I/O error occurs
-   * @deprecated Prefer {@code asCharSource(file, charset).readFirstLine()}. This method is
-   *     scheduled to be removed in October 2019.
+   * @deprecated Prefer {@code asCharSource(file, charset).readFirstLine()}.
    */
-  @Beta
   @Deprecated
+  @InlineMe(
+      replacement = "Files.asCharSource(file, charset).readFirstLine()",
+      imports = "com.google.common.io.Files")
+  @CheckForNull
   public
   static String readFirstLine(File file, Charset charset) throws IOException {
     return asCharSource(file, charset).readFirstLine();
@@ -550,7 +551,6 @@ static String readFirstLine(File file, Charset charset) throws IOException {
    * @return a mutable {@link List} containing all the lines
    * @throws IOException if an I/O error occurs
    */
-  @Beta
   public static List<String> readLines(File file, Charset charset) throws IOException {
     // don't use asCharSource(file, charset).readLines() because that returns
     // an immutable list, which would change the behavior of this method
@@ -582,14 +582,17 @@ public List<String> getResult() {
    * @param callback the {@link LineProcessor} to use to handle the lines
    * @return the output of processing the lines
    * @throws IOException if an I/O error occurs
-   * @deprecated Prefer {@code asCharSource(file, charset).readLines(callback)}. This method is
-   *     scheduled to be removed in October 2019.
+   * @deprecated Prefer {@code asCharSource(file, charset).readLines(callback)}.
    */
-  @Beta
   @Deprecated
+  @InlineMe(
+      replacement = "Files.asCharSource(file, charset).readLines(callback)",
+      imports = "com.google.common.io.Files")
   @CanIgnoreReturnValue // some processors won't return a useful result
+  @ParametricNullness
   public
-  static <T> T readLines(File file, Charset charset, LineProcessor<T> callback) throws IOException {
+  static <T extends @Nullable Object> T readLines(
+      File file, Charset charset, LineProcessor<T> callback) throws IOException {
     return asCharSource(file, charset).readLines(callback);
   }
 
@@ -602,14 +605,17 @@ static <T> T readLines(File file, Charset charset, LineProcessor<T> callback) th
    * @param processor the object to which the bytes of the file are passed.
    * @return the result of the byte processor
    * @throws IOException if an I/O error occurs
-   * @deprecated Prefer {@code asByteSource(file).read(processor)}. This method is scheduled to be
-   *     removed in October 2019.
+   * @deprecated Prefer {@code asByteSource(file).read(processor)}.
    */
-  @Beta
   @Deprecated
+  @InlineMe(
+      replacement = "Files.asByteSource(file).read(processor)",
+      imports = "com.google.common.io.Files")
   @CanIgnoreReturnValue // some processors won't return a useful result
+  @ParametricNullness
   public
-  static <T> T readBytes(File file, ByteProcessor<T> processor) throws IOException {
+  static <T extends @Nullable Object> T readBytes(File file, ByteProcessor<T> processor)
+      throws IOException {
     return asByteSource(file).read(processor);
   }
 
@@ -621,11 +627,12 @@ static <T> T readBytes(File file, ByteProcessor<T> processor) throws IOException
    * @return the {@link HashCode} of all of the bytes in the file
    * @throws IOException if an I/O error occurs
    * @since 12.0
-   * @deprecated Prefer {@code asByteSource(file).hash(hashFunction)}. This method is scheduled to
-   *     be removed in October 2019.
+   * @deprecated Prefer {@code asByteSource(file).hash(hashFunction)}.
    */
-  @Beta
   @Deprecated
+  @InlineMe(
+      replacement = "Files.asByteSource(file).hash(hashFunction)",
+      imports = "com.google.common.io.Files")
   public
   static HashCode hash(File file, HashFunction hashFunction) throws IOException {
     return asByteSource(file).hash(hashFunction);
@@ -646,7 +653,6 @@ static HashCode hash(File file, HashFunction hashFunction) throws IOException {
    * @see FileChannel#map(MapMode, long, long)
    * @since 2.0
    */
-  @Beta
   public static MappedByteBuffer map(File file) throws IOException {
     checkNotNull(file);
     return map(file, MapMode.READ_ONLY);
@@ -669,7 +675,6 @@ public static MappedByteBuffer map(File file) throws IOException {
    * @see FileChannel#map(MapMode, long, long)
    * @since 2.0
    */
-  @Beta
   public static MappedByteBuffer map(File file, MapMode mode) throws IOException {
     return mapInternal(file, mode, -1);
   }
@@ -693,7 +698,6 @@ public static MappedByteBuffer map(File file, MapMode mode) throws IOException {
    * @see FileChannel#map(MapMode, long, long)
    * @since 2.0
    */
-  @Beta
   public static MappedByteBuffer map(File file, MapMode mode, long size) throws IOException {
     checkArgument(size >= 0, "size (%s) may not be negative", size);
     return mapInternal(file, mode, size);
@@ -737,7 +741,6 @@ private static MappedByteBuffer mapInternal(File file, MapMode mode, long size)
    *
    * @since 11.0
    */
-  @Beta
   public static String simplifyPath(String pathname) {
     checkNotNull(pathname);
     if (pathname.length() == 0) {
@@ -798,7 +801,6 @@ public static String simplifyPath(String pathname) {
    *
    * @since 11.0
    */
-  @Beta
   public static String getFileExtension(String fullName) {
     checkNotNull(fullName);
     String fileName = new File(fullName).getName();
@@ -816,7 +818,6 @@ public static String getFileExtension(String fullName) {
    * @return The file name without its path or extension.
    * @since 14.0
    */
-  @Beta
   public static String getNameWithoutExtension(String file) {
     checkNotNull(file);
     String fileName = new File(file).getName();
@@ -872,7 +873,6 @@ public Iterable<File> successors(File file) {
    *
    * @since 15.0
    */
-  @Beta
   public static Predicate<File> isDirectory() {
     return FilePredicate.IS_DIRECTORY;
   }
@@ -882,7 +882,6 @@ public static Predicate<File> isDirectory() {
    *
    * @since 15.0
    */
-  @Beta
   public static Predicate<File> isFile() {
     return FilePredicate.IS_FILE;
   }
diff --git a/android/guava/src/com/google/common/io/Flushables.java b/android/guava/src/com/google/common/io/Flushables.java
index 9b1d6a096136..1f795a24ab24 100644
--- a/android/guava/src/com/google/common/io/Flushables.java
+++ b/android/guava/src/com/google/common/io/Flushables.java
@@ -29,6 +29,7 @@
  */
 @Beta
 @GwtIncompatible
+@ElementTypesAreNonnullByDefault
 public final class Flushables {
   private static final Logger logger = Logger.getLogger(Flushables.class.getName());
 
diff --git a/android/guava/src/com/google/common/io/Java8Compatibility.java b/android/guava/src/com/google/common/io/Java8Compatibility.java
index 62b5c2ea5b7f..705d97b4dfa5 100644
--- a/android/guava/src/com/google/common/io/Java8Compatibility.java
+++ b/android/guava/src/com/google/common/io/Java8Compatibility.java
@@ -22,6 +22,7 @@
  * https://github.com/google/guava/issues/3990
  */
 @GwtIncompatible
+@ElementTypesAreNonnullByDefault
 final class Java8Compatibility {
   static void clear(Buffer b) {
     b.clear();
@@ -35,9 +36,17 @@ static void limit(Buffer b, int limit) {
     b.limit(limit);
   }
 
+  static void mark(Buffer b) {
+    b.mark();
+  }
+
   static void position(Buffer b, int position) {
     b.position(position);
   }
 
+  static void reset(Buffer b) {
+    b.reset();
+  }
+
   private Java8Compatibility() {}
 }
diff --git a/android/guava/src/com/google/common/io/LineBuffer.java b/android/guava/src/com/google/common/io/LineBuffer.java
index a8e775c72bdf..f944abc49099 100644
--- a/android/guava/src/com/google/common/io/LineBuffer.java
+++ b/android/guava/src/com/google/common/io/LineBuffer.java
@@ -30,6 +30,7 @@
  * @since 1.0
  */
 @GwtIncompatible
+@ElementTypesAreNonnullByDefault
 abstract class LineBuffer {
   /** Holds partial line contents. */
   private StringBuilder line = new StringBuilder();
diff --git a/android/guava/src/com/google/common/io/LineProcessor.java b/android/guava/src/com/google/common/io/LineProcessor.java
index 65ded53a4701..e28bebcc5f2b 100644
--- a/android/guava/src/com/google/common/io/LineProcessor.java
+++ b/android/guava/src/com/google/common/io/LineProcessor.java
@@ -18,6 +18,7 @@
 import com.google.common.annotations.GwtIncompatible;
 import com.google.errorprone.annotations.CanIgnoreReturnValue;
 import java.io.IOException;
+import org.checkerframework.checker.nullness.qual.Nullable;
 
 /**
  * A callback to be used with the streaming {@code readLines} methods.
@@ -30,7 +31,8 @@
  */
 @Beta
 @GwtIncompatible
-public interface LineProcessor<T> {
+@ElementTypesAreNonnullByDefault
+public interface LineProcessor<T extends @Nullable Object> {
 
   /**
    * This method will be called once for each line.
@@ -42,5 +44,6 @@ public interface LineProcessor<T> {
   boolean processLine(String line) throws IOException;
 
   /** Return the result of processing all the lines. */
+  @ParametricNullness
   T getResult();
 }
diff --git a/android/guava/src/com/google/common/io/LineReader.java b/android/guava/src/com/google/common/io/LineReader.java
index 55d00b14a4b4..2c57ac4546b7 100644
--- a/android/guava/src/com/google/common/io/LineReader.java
+++ b/android/guava/src/com/google/common/io/LineReader.java
@@ -25,7 +25,7 @@
 import java.nio.CharBuffer;
 import java.util.ArrayDeque;
 import java.util.Queue;
-import org.checkerframework.checker.nullness.compatqual.NullableDecl;
+import javax.annotation.CheckForNull;
 
 /**
  * A class for reading lines of text. Provides the same functionality as {@link
@@ -37,9 +37,10 @@
  */
 @Beta
 @GwtIncompatible
+@ElementTypesAreNonnullByDefault
 public final class LineReader {
   private final Readable readable;
-  @NullableDecl private final Reader reader;
+  @CheckForNull private final Reader reader;
   private final CharBuffer cbuf = createBuffer();
   private final char[] buf = cbuf.array();
 
@@ -68,6 +69,7 @@ public LineReader(Readable readable) {
    * @throws IOException if an I/O error occurs
    */
   @CanIgnoreReturnValue // to skip a line
+  @CheckForNull
   public String readLine() throws IOException {
     while (lines.peek() == null) {
       Java8Compatibility.clear(cbuf);
diff --git a/android/guava/src/com/google/common/io/LittleEndianDataInputStream.java b/android/guava/src/com/google/common/io/LittleEndianDataInputStream.java
index 8f5f23da41ed..88c8e27bc3f9 100644
--- a/android/guava/src/com/google/common/io/LittleEndianDataInputStream.java
+++ b/android/guava/src/com/google/common/io/LittleEndianDataInputStream.java
@@ -41,6 +41,7 @@
  */
 @Beta
 @GwtIncompatible
+@ElementTypesAreNonnullByDefault
 public final class LittleEndianDataInputStream extends FilterInputStream implements DataInput {
 
   /**
diff --git a/android/guava/src/com/google/common/io/LittleEndianDataOutputStream.java b/android/guava/src/com/google/common/io/LittleEndianDataOutputStream.java
index e5e398f615ba..6e51aff49d92 100644
--- a/android/guava/src/com/google/common/io/LittleEndianDataOutputStream.java
+++ b/android/guava/src/com/google/common/io/LittleEndianDataOutputStream.java
@@ -37,6 +37,7 @@
  */
 @Beta
 @GwtIncompatible
+@ElementTypesAreNonnullByDefault
 public final class LittleEndianDataOutputStream extends FilterOutputStream implements DataOutput {
 
   /**
diff --git a/android/guava/src/com/google/common/io/MultiInputStream.java b/android/guava/src/com/google/common/io/MultiInputStream.java
index bae8e391964a..9a7e0fd1c0e7 100644
--- a/android/guava/src/com/google/common/io/MultiInputStream.java
+++ b/android/guava/src/com/google/common/io/MultiInputStream.java
@@ -20,7 +20,7 @@
 import java.io.IOException;
 import java.io.InputStream;
 import java.util.Iterator;
-import org.checkerframework.checker.nullness.compatqual.NullableDecl;
+import javax.annotation.CheckForNull;
 
 /**
  * An {@link InputStream} that concatenates multiple substreams. At most one stream will be open at
@@ -30,10 +30,11 @@
  * @since 1.0
  */
 @GwtIncompatible
+@ElementTypesAreNonnullByDefault
 final class MultiInputStream extends InputStream {
 
   private Iterator<? extends ByteSource> it;
-  @NullableDecl private InputStream in;
+  @CheckForNull private InputStream in;
 
   /**
    * Creates a new instance.
@@ -90,7 +91,8 @@ public int read() throws IOException {
   }
 
   @Override
-  public int read(@NullableDecl byte[] b, int off, int len) throws IOException {
+  public int read(byte[] b, int off, int len) throws IOException {
+    checkNotNull(b);
     while (in != null) {
       int result = in.read(b, off, len);
       if (result != -1) {
diff --git a/android/guava/src/com/google/common/io/MultiReader.java b/android/guava/src/com/google/common/io/MultiReader.java
index d075727ef08f..cc36e527b620 100644
--- a/android/guava/src/com/google/common/io/MultiReader.java
+++ b/android/guava/src/com/google/common/io/MultiReader.java
@@ -14,12 +14,14 @@
 
 package com.google.common.io;
 
+import static com.google.common.base.Preconditions.checkNotNull;
+
 import com.google.common.annotations.GwtIncompatible;
 import com.google.common.base.Preconditions;
 import java.io.IOException;
 import java.io.Reader;
 import java.util.Iterator;
-import org.checkerframework.checker.nullness.compatqual.NullableDecl;
+import javax.annotation.CheckForNull;
 
 /**
  * A {@link Reader} that concatenates multiple readers.
@@ -28,9 +30,10 @@
  * @since 1.0
  */
 @GwtIncompatible
+@ElementTypesAreNonnullByDefault
 class MultiReader extends Reader {
   private final Iterator<? extends CharSource> it;
-  @NullableDecl private Reader current;
+  @CheckForNull private Reader current;
 
   MultiReader(Iterator<? extends CharSource> readers) throws IOException {
     this.it = readers;
@@ -46,7 +49,8 @@ private void advance() throws IOException {
   }
 
   @Override
-  public int read(@NullableDecl char[] cbuf, int off, int len) throws IOException {
+  public int read(char[] cbuf, int off, int len) throws IOException {
+    checkNotNull(cbuf);
     if (current == null) {
       return -1;
     }
diff --git a/android/guava/src/com/google/common/io/ParametricNullness.java b/android/guava/src/com/google/common/io/ParametricNullness.java
new file mode 100644
index 000000000000..98da765852b6
--- /dev/null
+++ b/android/guava/src/com/google/common/io/ParametricNullness.java
@@ -0,0 +1,52 @@
+/*
+ * Copyright (C) 2021 The Guava Authors
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package com.google.common.io;
+
+import static java.lang.annotation.ElementType.FIELD;
+import static java.lang.annotation.ElementType.METHOD;
+import static java.lang.annotation.ElementType.PARAMETER;
+import static java.lang.annotation.RetentionPolicy.RUNTIME;
+
+import com.google.common.annotations.GwtCompatible;
+import java.lang.annotation.Retention;
+import java.lang.annotation.Target;
+
+/**
+ * Marks a "top-level" type-variable usage as the closest we can get to "non-nullable when
+ * non-nullable; nullable when nullable" (like the Android <a
+ * href="https://android.googlesource.com/platform/libcore/+/master/luni/src/main/java/libcore/util/NullFromTypeParam.java">{@code
+ * NullFromTypeParam}</a>).
+ *
+ * <p>Consumers of this annotation include:
+ *
+ * <ul>
+ *   <li>Kotlin, for which it makes the type-variable usage (a) a Kotlin platform type when the type
+ *       argument is non-nullable and (b) nullable when the type argument is nullable. We use this
+ *       to "undo" {@link ElementTypesAreNonnullByDefault}.
+ *   <li><a href="https://developers.google.com/j2objc">J2ObjC</a>
+ *   <li>{@code NullPointerTester}, at least in the Android backport (where the type-use annotations
+ *       {@code NullPointerTester} would need are not available) and in case of <a
+ *       href="https://bugs.openjdk.java.net/browse/JDK-8202469">JDK-8202469</a>
+ * </ul>
+ *
+ */
+@GwtCompatible
+@Retention(RUNTIME)
+@Target({FIELD, METHOD, PARAMETER})
+@javax.annotation.meta.TypeQualifierNickname
+@javax.annotation.Nonnull(when = javax.annotation.meta.When.UNKNOWN)
+@interface ParametricNullness {}
diff --git a/android/guava/src/com/google/common/io/PatternFilenameFilter.java b/android/guava/src/com/google/common/io/PatternFilenameFilter.java
index 43e4f30154fa..3cb2371e2fd4 100644
--- a/android/guava/src/com/google/common/io/PatternFilenameFilter.java
+++ b/android/guava/src/com/google/common/io/PatternFilenameFilter.java
@@ -21,7 +21,6 @@
 import java.io.FilenameFilter;
 import java.util.regex.Pattern;
 import java.util.regex.PatternSyntaxException;
-import org.checkerframework.checker.nullness.compatqual.NullableDecl;
 
 /**
  * File name filter that only accepts files matching a regular expression. This class is thread-safe
@@ -32,6 +31,7 @@
  */
 @Beta
 @GwtIncompatible
+@ElementTypesAreNonnullByDefault
 public final class PatternFilenameFilter implements FilenameFilter {
 
   private final Pattern pattern;
@@ -55,8 +55,21 @@ public PatternFilenameFilter(Pattern pattern) {
     this.pattern = Preconditions.checkNotNull(pattern);
   }
 
+  /*
+   * Our implementation works fine with a null `dir`. However, there's nothing in the documentation
+   * of the supertype that suggests that implementations are expected to tolerate null. That said, I
+   * see calls in Google code that pass a null `dir` to a FilenameFilter.... So let's declare the
+   * parameter as non-nullable (since passing null to a FilenameFilter is unsafe in general), but if
+   * someone still manages to pass null, let's continue to have the method work.
+   *
+   * (PatternFilenameFilter is of course one of those classes that shouldn't be a publicly visible
+   * class to begin with but rather something returned from a static factory method whose declared
+   * return type is plain FilenameFilter. If we made such a change, then the annotation we choose
+   * here would have no significance to end users, who would be forced to conform to the signature
+   * used in FilenameFilter.)
+   */
   @Override
-  public boolean accept(@NullableDecl File dir, String fileName) {
+  public boolean accept(File dir, String fileName) {
     return pattern.matcher(fileName).matches();
   }
 }
diff --git a/android/guava/src/com/google/common/io/ReaderInputStream.java b/android/guava/src/com/google/common/io/ReaderInputStream.java
index eeb64e4e0d8c..75f8a3e1e39b 100644
--- a/android/guava/src/com/google/common/io/ReaderInputStream.java
+++ b/android/guava/src/com/google/common/io/ReaderInputStream.java
@@ -44,6 +44,7 @@
  * @author Chris Nokleberg
  */
 @GwtIncompatible
+@ElementTypesAreNonnullByDefault
 final class ReaderInputStream extends InputStream {
   private final Reader reader;
   private final CharsetEncoder encoder;
diff --git a/android/guava/src/com/google/common/io/Resources.java b/android/guava/src/com/google/common/io/Resources.java
index d64bf3d51d65..d1e37070a91c 100644
--- a/android/guava/src/com/google/common/io/Resources.java
+++ b/android/guava/src/com/google/common/io/Resources.java
@@ -17,7 +17,6 @@
 import static com.google.common.base.Preconditions.checkArgument;
 import static com.google.common.base.Preconditions.checkNotNull;
 
-import com.google.common.annotations.Beta;
 import com.google.common.annotations.GwtIncompatible;
 import com.google.common.base.Charsets;
 import com.google.common.base.MoreObjects;
@@ -29,21 +28,20 @@
 import java.net.URL;
 import java.nio.charset.Charset;
 import java.util.List;
+import org.checkerframework.checker.nullness.qual.Nullable;
 
 /**
  * Provides utility methods for working with resources in the classpath. Note that even though these
  * methods use {@link URL} parameters, they are usually not appropriate for HTTP or other
  * non-classpath resources.
  *
- * <p>All method parameters must be non-null unless documented otherwise.
- *
  * @author Chris Nokleberg
  * @author Ben Yu
  * @author Colin Decker
  * @since 1.0
  */
-@Beta
 @GwtIncompatible
+@ElementTypesAreNonnullByDefault
 public final class Resources {
   private Resources() {}
 
@@ -121,8 +119,9 @@ public static String toString(URL url, Charset charset) throws IOException {
    * @throws IOException if an I/O error occurs
    */
   @CanIgnoreReturnValue // some processors won't return a useful result
-  public static <T> T readLines(URL url, Charset charset, LineProcessor<T> callback)
-      throws IOException {
+  @ParametricNullness
+  public static <T extends @Nullable Object> T readLines(
+      URL url, Charset charset, LineProcessor<T> callback) throws IOException {
     return asCharSource(url, charset).readLines(callback);
   }
 
diff --git a/android/guava/src/com/google/common/math/BigDecimalMath.java b/android/guava/src/com/google/common/math/BigDecimalMath.java
index b5c23f8dd993..33a55d356312 100644
--- a/android/guava/src/com/google/common/math/BigDecimalMath.java
+++ b/android/guava/src/com/google/common/math/BigDecimalMath.java
@@ -25,6 +25,7 @@
  * @since 30.0
  */
 @GwtIncompatible
+@ElementTypesAreNonnullByDefault
 public class BigDecimalMath {
   private BigDecimalMath() {}
 
diff --git a/android/guava/src/com/google/common/math/BigIntegerMath.java b/android/guava/src/com/google/common/math/BigIntegerMath.java
index bf443e9b145b..6ef1e81ed4d7 100644
--- a/android/guava/src/com/google/common/math/BigIntegerMath.java
+++ b/android/guava/src/com/google/common/math/BigIntegerMath.java
@@ -48,6 +48,7 @@
  * @since 11.0
  */
 @GwtCompatible(emulated = true)
+@ElementTypesAreNonnullByDefault
 public final class BigIntegerMath {
   /**
    * Returns the smallest power of two greater than or equal to {@code x}. This is equivalent to
diff --git a/android/guava/src/com/google/common/math/DoubleMath.java b/android/guava/src/com/google/common/math/DoubleMath.java
index 8745e41ba643..cdd0a4b39e3b 100644
--- a/android/guava/src/com/google/common/math/DoubleMath.java
+++ b/android/guava/src/com/google/common/math/DoubleMath.java
@@ -46,6 +46,7 @@
  * @since 11.0
  */
 @GwtCompatible(emulated = true)
+@ElementTypesAreNonnullByDefault
 public final class DoubleMath {
   /*
    * This method returns a value y such that rounding y DOWN (towards zero) gives the same result as
@@ -432,7 +433,7 @@ public static double mean(double... values) {
   @Deprecated
   public static double mean(int... values) {
     checkArgument(values.length > 0, "Cannot take mean of 0 values");
-    // The upper bound on the the length of an array and the bounds on the int values mean that, in
+    // The upper bound on the length of an array and the bounds on the int values mean that, in
     // this case only, we can compute the sum as a long without risking overflow or loss of
     // precision. So we do that, as it's slightly quicker than the Knuth algorithm.
     long sum = 0;
diff --git a/android/guava/src/com/google/common/math/DoubleUtils.java b/android/guava/src/com/google/common/math/DoubleUtils.java
index 4183195fc714..d4a07e9dfcfe 100644
--- a/android/guava/src/com/google/common/math/DoubleUtils.java
+++ b/android/guava/src/com/google/common/math/DoubleUtils.java
@@ -33,6 +33,7 @@
  * @author Louis Wasserman
  */
 @GwtIncompatible
+@ElementTypesAreNonnullByDefault
 final class DoubleUtils {
   private DoubleUtils() {}
 
diff --git a/android/guava/src/com/google/common/math/ElementTypesAreNonnullByDefault.java b/android/guava/src/com/google/common/math/ElementTypesAreNonnullByDefault.java
new file mode 100644
index 000000000000..84999ea49499
--- /dev/null
+++ b/android/guava/src/com/google/common/math/ElementTypesAreNonnullByDefault.java
@@ -0,0 +1,41 @@
+/*
+ * Copyright (C) 2021 The Guava Authors
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package com.google.common.math;
+
+import static java.lang.annotation.ElementType.FIELD;
+import static java.lang.annotation.ElementType.METHOD;
+import static java.lang.annotation.ElementType.PARAMETER;
+import static java.lang.annotation.ElementType.TYPE;
+import static java.lang.annotation.RetentionPolicy.RUNTIME;
+
+import com.google.common.annotations.GwtCompatible;
+import java.lang.annotation.Retention;
+import java.lang.annotation.Target;
+import javax.annotation.Nonnull;
+import javax.annotation.meta.TypeQualifierDefault;
+
+/**
+ * Marks all "top-level" types as non-null in a way that is recognized by Kotlin. Note that this
+ * unfortunately includes type-variable usages, so we also provide {@link ParametricNullness} to
+ * "undo" it as best we can.
+ */
+@GwtCompatible
+@Retention(RUNTIME)
+@Target(TYPE)
+@TypeQualifierDefault({FIELD, METHOD, PARAMETER})
+@Nonnull
+@interface ElementTypesAreNonnullByDefault {}
diff --git a/android/guava/src/com/google/common/math/IntMath.java b/android/guava/src/com/google/common/math/IntMath.java
index 78aedda98db4..17a18c69999a 100644
--- a/android/guava/src/com/google/common/math/IntMath.java
+++ b/android/guava/src/com/google/common/math/IntMath.java
@@ -48,6 +48,7 @@
  * @since 11.0
  */
 @GwtCompatible(emulated = true)
+@ElementTypesAreNonnullByDefault
 public final class IntMath {
   // NOTE: Whenever both tests are cheap and functional, it's faster to use &, | instead of &&, ||
 
diff --git a/android/guava/src/com/google/common/math/LinearTransformation.java b/android/guava/src/com/google/common/math/LinearTransformation.java
index 485b04660902..4cc1eb87dbe9 100644
--- a/android/guava/src/com/google/common/math/LinearTransformation.java
+++ b/android/guava/src/com/google/common/math/LinearTransformation.java
@@ -21,6 +21,7 @@
 import com.google.common.annotations.Beta;
 import com.google.common.annotations.GwtIncompatible;
 import com.google.errorprone.annotations.concurrent.LazyInit;
+import javax.annotation.CheckForNull;
 
 /**
  * The representation of a linear transformation between real numbers {@code x} and {@code y}.
@@ -35,6 +36,7 @@
  */
 @Beta
 @GwtIncompatible
+@ElementTypesAreNonnullByDefault
 public abstract class LinearTransformation {
 
   /**
@@ -161,7 +163,7 @@ private static final class RegularLinearTransformation extends LinearTransformat
     final double slope;
     final double yIntercept;
 
-    @LazyInit LinearTransformation inverse;
+    @CheckForNull @LazyInit LinearTransformation inverse;
 
     RegularLinearTransformation(double slope, double yIntercept) {
       this.slope = slope;
@@ -219,7 +221,7 @@ private static final class VerticalLinearTransformation extends LinearTransforma
 
     final double x;
 
-    @LazyInit LinearTransformation inverse;
+    @CheckForNull @LazyInit LinearTransformation inverse;
 
     VerticalLinearTransformation(double x) {
       this.x = x;
diff --git a/android/guava/src/com/google/common/math/LongMath.java b/android/guava/src/com/google/common/math/LongMath.java
index 420b48a9b453..dd5ff069423b 100644
--- a/android/guava/src/com/google/common/math/LongMath.java
+++ b/android/guava/src/com/google/common/math/LongMath.java
@@ -49,6 +49,7 @@
  * @since 11.0
  */
 @GwtCompatible(emulated = true)
+@ElementTypesAreNonnullByDefault
 public final class LongMath {
   // NOTE: Whenever both tests are cheap and functional, it's faster to use &, | instead of &&, ||
 
@@ -424,7 +425,7 @@ public static long divide(long p, long q, RoundingMode mode) {
         // subtracting two nonnegative longs can't overflow
         // cmpRemToHalfDivisor has the same sign as compare(abs(rem), abs(q) / 2).
         if (cmpRemToHalfDivisor == 0) { // exactly on the half mark
-          increment = (mode == HALF_UP | (mode == HALF_EVEN & (div & 1) != 0));
+          increment = (mode == HALF_UP || (mode == HALF_EVEN && (div & 1) != 0));
         } else {
           increment = cmpRemToHalfDivisor > 0; // closer to the UP value
         }
diff --git a/android/guava/src/com/google/common/math/MathPreconditions.java b/android/guava/src/com/google/common/math/MathPreconditions.java
index 5f925d38d774..37d608a82329 100644
--- a/android/guava/src/com/google/common/math/MathPreconditions.java
+++ b/android/guava/src/com/google/common/math/MathPreconditions.java
@@ -18,7 +18,6 @@
 import com.google.errorprone.annotations.CanIgnoreReturnValue;
 import java.math.BigInteger;
 import java.math.RoundingMode;
-import org.checkerframework.checker.nullness.compatqual.NullableDecl;
 
 /**
  * A collection of preconditions for math functions.
@@ -27,50 +26,51 @@
  */
 @GwtCompatible
 @CanIgnoreReturnValue
+@ElementTypesAreNonnullByDefault
 final class MathPreconditions {
-  static int checkPositive(@NullableDecl String role, int x) {
+  static int checkPositive(String role, int x) {
     if (x <= 0) {
       throw new IllegalArgumentException(role + " (" + x + ") must be > 0");
     }
     return x;
   }
 
-  static long checkPositive(@NullableDecl String role, long x) {
+  static long checkPositive(String role, long x) {
     if (x <= 0) {
       throw new IllegalArgumentException(role + " (" + x + ") must be > 0");
     }
     return x;
   }
 
-  static BigInteger checkPositive(@NullableDecl String role, BigInteger x) {
+  static BigInteger checkPositive(String role, BigInteger x) {
     if (x.signum() <= 0) {
       throw new IllegalArgumentException(role + " (" + x + ") must be > 0");
     }
     return x;
   }
 
-  static int checkNonNegative(@NullableDecl String role, int x) {
+  static int checkNonNegative(String role, int x) {
     if (x < 0) {
       throw new IllegalArgumentException(role + " (" + x + ") must be >= 0");
     }
     return x;
   }
 
-  static long checkNonNegative(@NullableDecl String role, long x) {
+  static long checkNonNegative(String role, long x) {
     if (x < 0) {
       throw new IllegalArgumentException(role + " (" + x + ") must be >= 0");
     }
     return x;
   }
 
-  static BigInteger checkNonNegative(@NullableDecl String role, BigInteger x) {
+  static BigInteger checkNonNegative(String role, BigInteger x) {
     if (x.signum() < 0) {
       throw new IllegalArgumentException(role + " (" + x + ") must be >= 0");
     }
     return x;
   }
 
-  static double checkNonNegative(@NullableDecl String role, double x) {
+  static double checkNonNegative(String role, double x) {
     if (!(x >= 0)) { // not x < 0, to work with NaN.
       throw new IllegalArgumentException(role + " (" + x + ") must be >= 0");
     }
diff --git a/android/guava/src/com/google/common/math/PairedStats.java b/android/guava/src/com/google/common/math/PairedStats.java
index a636e51d3160..31ab9b71966f 100644
--- a/android/guava/src/com/google/common/math/PairedStats.java
+++ b/android/guava/src/com/google/common/math/PairedStats.java
@@ -28,7 +28,7 @@
 import java.io.Serializable;
 import java.nio.ByteBuffer;
 import java.nio.ByteOrder;
-import org.checkerframework.checker.nullness.compatqual.NullableDecl;
+import javax.annotation.CheckForNull;
 
 /**
  * An immutable value object capturing some basic statistics about a collection of paired double
@@ -39,6 +39,7 @@
  */
 @Beta
 @GwtIncompatible
+@ElementTypesAreNonnullByDefault
 public final class PairedStats implements Serializable {
 
   private final Stats xStats;
@@ -213,7 +214,7 @@ public LinearTransformation leastSquaresFit() {
    * guarantees {@code strictfp}-like semantics.)
    */
   @Override
-  public boolean equals(@NullableDecl Object obj) {
+  public boolean equals(@CheckForNull Object obj) {
     if (obj == null) {
       return false;
     }
diff --git a/android/guava/src/com/google/common/math/PairedStatsAccumulator.java b/android/guava/src/com/google/common/math/PairedStatsAccumulator.java
index a9884959a04a..072ef13b3b17 100644
--- a/android/guava/src/com/google/common/math/PairedStatsAccumulator.java
+++ b/android/guava/src/com/google/common/math/PairedStatsAccumulator.java
@@ -32,6 +32,7 @@
  */
 @Beta
 @GwtIncompatible
+@ElementTypesAreNonnullByDefault
 public final class PairedStatsAccumulator {
 
   // These fields must satisfy the requirements of PairedStats' constructor as well as those of the
diff --git a/android/guava/src/com/google/common/math/ParametricNullness.java b/android/guava/src/com/google/common/math/ParametricNullness.java
new file mode 100644
index 000000000000..8e57826e4335
--- /dev/null
+++ b/android/guava/src/com/google/common/math/ParametricNullness.java
@@ -0,0 +1,52 @@
+/*
+ * Copyright (C) 2021 The Guava Authors
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package com.google.common.math;
+
+import static java.lang.annotation.ElementType.FIELD;
+import static java.lang.annotation.ElementType.METHOD;
+import static java.lang.annotation.ElementType.PARAMETER;
+import static java.lang.annotation.RetentionPolicy.RUNTIME;
+
+import com.google.common.annotations.GwtCompatible;
+import java.lang.annotation.Retention;
+import java.lang.annotation.Target;
+
+/**
+ * Marks a "top-level" type-variable usage as the closest we can get to "non-nullable when
+ * non-nullable; nullable when nullable" (like the Android <a
+ * href="https://android.googlesource.com/platform/libcore/+/master/luni/src/main/java/libcore/util/NullFromTypeParam.java">{@code
+ * NullFromTypeParam}</a>).
+ *
+ * <p>Consumers of this annotation include:
+ *
+ * <ul>
+ *   <li>Kotlin, for which it makes the type-variable usage (a) a Kotlin platform type when the type
+ *       argument is non-nullable and (b) nullable when the type argument is nullable. We use this
+ *       to "undo" {@link ElementTypesAreNonnullByDefault}.
+ *   <li><a href="https://developers.google.com/j2objc">J2ObjC</a>
+ *   <li>{@code NullPointerTester}, at least in the Android backport (where the type-use annotations
+ *       {@code NullPointerTester} would need are not available) and in case of <a
+ *       href="https://bugs.openjdk.java.net/browse/JDK-8202469">JDK-8202469</a>
+ * </ul>
+ *
+ */
+@GwtCompatible
+@Retention(RUNTIME)
+@Target({FIELD, METHOD, PARAMETER})
+@javax.annotation.meta.TypeQualifierNickname
+@javax.annotation.Nonnull(when = javax.annotation.meta.When.UNKNOWN)
+@interface ParametricNullness {}
diff --git a/android/guava/src/com/google/common/math/Quantiles.java b/android/guava/src/com/google/common/math/Quantiles.java
index 7aac58f077ea..6ddea9bcfdc7 100644
--- a/android/guava/src/com/google/common/math/Quantiles.java
+++ b/android/guava/src/com/google/common/math/Quantiles.java
@@ -128,6 +128,7 @@
  */
 @Beta
 @GwtIncompatible
+@ElementTypesAreNonnullByDefault
 public final class Quantiles {
 
   /** Specifies the computation of a median (i.e. the 1st 2-quantile). */
diff --git a/android/guava/src/com/google/common/math/Stats.java b/android/guava/src/com/google/common/math/Stats.java
index 94939383a430..c0837496dec3 100644
--- a/android/guava/src/com/google/common/math/Stats.java
+++ b/android/guava/src/com/google/common/math/Stats.java
@@ -32,7 +32,7 @@
 import java.nio.ByteBuffer;
 import java.nio.ByteOrder;
 import java.util.Iterator;
-import org.checkerframework.checker.nullness.compatqual.NullableDecl;
+import javax.annotation.CheckForNull;
 
 /**
  * A bundle of statistical summary values -- sum, count, mean/average, min and max, and several
@@ -60,6 +60,7 @@
  */
 @Beta
 @GwtIncompatible
+@ElementTypesAreNonnullByDefault
 public final class Stats implements Serializable {
 
   private final long count;
@@ -340,7 +341,7 @@ public double max() {
    * {@code strictfp}-like semantics.)
    */
   @Override
-  public boolean equals(@NullableDecl Object obj) {
+  public boolean equals(@CheckForNull Object obj) {
     if (obj == null) {
       return false;
     }
diff --git a/android/guava/src/com/google/common/math/StatsAccumulator.java b/android/guava/src/com/google/common/math/StatsAccumulator.java
index 54468cf4f963..f7d7a629032d 100644
--- a/android/guava/src/com/google/common/math/StatsAccumulator.java
+++ b/android/guava/src/com/google/common/math/StatsAccumulator.java
@@ -34,6 +34,7 @@
  */
 @Beta
 @GwtIncompatible
+@ElementTypesAreNonnullByDefault
 public final class StatsAccumulator {
 
   // These fields must satisfy the requirements of Stats' constructor as well as those of the stat
diff --git a/android/guava/src/com/google/common/math/ToDoubleRounder.java b/android/guava/src/com/google/common/math/ToDoubleRounder.java
index 7525e3f990f1..2e7e7fae0944 100644
--- a/android/guava/src/com/google/common/math/ToDoubleRounder.java
+++ b/android/guava/src/com/google/common/math/ToDoubleRounder.java
@@ -25,6 +25,7 @@
  * a {@link RoundingMode}.
  */
 @GwtIncompatible
+@ElementTypesAreNonnullByDefault
 abstract class ToDoubleRounder<X extends Number & Comparable<X>> {
   /**
    * Returns x rounded to either the greatest double less than or equal to the precise value of x,
diff --git a/android/guava/src/com/google/common/net/ElementTypesAreNonnullByDefault.java b/android/guava/src/com/google/common/net/ElementTypesAreNonnullByDefault.java
new file mode 100644
index 000000000000..d8cfd7377d0e
--- /dev/null
+++ b/android/guava/src/com/google/common/net/ElementTypesAreNonnullByDefault.java
@@ -0,0 +1,41 @@
+/*
+ * Copyright (C) 2021 The Guava Authors
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package com.google.common.net;
+
+import static java.lang.annotation.ElementType.FIELD;
+import static java.lang.annotation.ElementType.METHOD;
+import static java.lang.annotation.ElementType.PARAMETER;
+import static java.lang.annotation.ElementType.TYPE;
+import static java.lang.annotation.RetentionPolicy.RUNTIME;
+
+import com.google.common.annotations.GwtCompatible;
+import java.lang.annotation.Retention;
+import java.lang.annotation.Target;
+import javax.annotation.Nonnull;
+import javax.annotation.meta.TypeQualifierDefault;
+
+/**
+ * Marks all "top-level" types as non-null in a way that is recognized by Kotlin. Note that this
+ * unfortunately includes type-variable usages, so we also provide {@link ParametricNullness} to
+ * "undo" it as best we can.
+ */
+@GwtCompatible
+@Retention(RUNTIME)
+@Target(TYPE)
+@TypeQualifierDefault({FIELD, METHOD, PARAMETER})
+@Nonnull
+@interface ElementTypesAreNonnullByDefault {}
diff --git a/android/guava/src/com/google/common/net/HostAndPort.java b/android/guava/src/com/google/common/net/HostAndPort.java
index df8ded405349..a27eb65ff3ba 100644
--- a/android/guava/src/com/google/common/net/HostAndPort.java
+++ b/android/guava/src/com/google/common/net/HostAndPort.java
@@ -18,13 +18,14 @@
 import static com.google.common.base.Preconditions.checkNotNull;
 import static com.google.common.base.Preconditions.checkState;
 
-import com.google.common.annotations.Beta;
 import com.google.common.annotations.GwtCompatible;
+import com.google.common.base.CharMatcher;
 import com.google.common.base.Objects;
 import com.google.common.base.Strings;
+import com.google.errorprone.annotations.CanIgnoreReturnValue;
 import com.google.errorprone.annotations.Immutable;
 import java.io.Serializable;
-import org.checkerframework.checker.nullness.compatqual.NullableDecl;
+import javax.annotation.CheckForNull;
 
 /**
  * An immutable representation of a host and port.
@@ -59,9 +60,9 @@
  * @author Paul Marks
  * @since 10.0
  */
-@Beta
 @Immutable
 @GwtCompatible
+@ElementTypesAreNonnullByDefault
 public final class HostAndPort implements Serializable {
   /** Magic value indicating the absence of a port number. */
   private static final int NO_PORT = -1;
@@ -162,6 +163,7 @@ public static HostAndPort fromHost(String host) {
    * @return if parsing was successful, a populated HostAndPort object.
    * @throws IllegalArgumentException if nothing meaningful could be parsed.
    */
+  @CanIgnoreReturnValue // TODO(b/219820829): consider removing
   public static HostAndPort fromString(String hostPortString) {
     checkNotNull(hostPortString);
     String host;
@@ -189,7 +191,10 @@ public static HostAndPort fromString(String hostPortString) {
     if (!Strings.isNullOrEmpty(portString)) {
       // Try to parse the whole port string as a number.
       // JDK7 accepts leading plus signs. We don't want to.
-      checkArgument(!portString.startsWith("+"), "Unparseable port number: %s", hostPortString);
+      checkArgument(
+          !portString.startsWith("+") && CharMatcher.ascii().matchesAllOf(portString),
+          "Unparseable port number: %s",
+          hostPortString);
       try {
         port = Integer.parseInt(portString);
       } catch (NumberFormatException e) {
@@ -209,14 +214,12 @@ public static HostAndPort fromString(String hostPortString) {
    * @throws IllegalArgumentException if parsing the bracketed host-port string fails.
    */
   private static String[] getHostAndPortFromBracketedHost(String hostPortString) {
-    int colonIndex = 0;
-    int closeBracketIndex = 0;
     checkArgument(
         hostPortString.charAt(0) == '[',
         "Bracketed host-port string must start with a bracket: %s",
         hostPortString);
-    colonIndex = hostPortString.indexOf(':');
-    closeBracketIndex = hostPortString.lastIndexOf(']');
+    int colonIndex = hostPortString.indexOf(':');
+    int closeBracketIndex = hostPortString.lastIndexOf(']');
     checkArgument(
         colonIndex > -1 && closeBracketIndex > colonIndex,
         "Invalid bracketed host/port: %s",
@@ -271,13 +274,14 @@ public HostAndPort withDefaultPort(int defaultPort) {
    * @return {@code this}, to enable chaining of calls.
    * @throws IllegalArgumentException if bracketless IPv6 is detected.
    */
+  @CanIgnoreReturnValue
   public HostAndPort requireBracketsForIPv6() {
     checkArgument(!hasBracketlessColons, "Possible bracketless IPv6 literal: %s", host);
     return this;
   }
 
   @Override
-  public boolean equals(@NullableDecl Object other) {
+  public boolean equals(@CheckForNull Object other) {
     if (this == other) {
       return true;
     }
diff --git a/android/guava/src/com/google/common/net/HostSpecifier.java b/android/guava/src/com/google/common/net/HostSpecifier.java
index 3f6f5690961e..c57f3d97593c 100644
--- a/android/guava/src/com/google/common/net/HostSpecifier.java
+++ b/android/guava/src/com/google/common/net/HostSpecifier.java
@@ -14,12 +14,12 @@
 
 package com.google.common.net;
 
-import com.google.common.annotations.Beta;
 import com.google.common.annotations.GwtIncompatible;
 import com.google.common.base.Preconditions;
+import com.google.errorprone.annotations.CanIgnoreReturnValue;
 import java.net.InetAddress;
 import java.text.ParseException;
-import org.checkerframework.checker.nullness.compatqual.NullableDecl;
+import javax.annotation.CheckForNull;
 
 /**
  * A syntactically valid host specifier, suitable for use in a URI. This may be either a numeric IP
@@ -41,8 +41,8 @@
  * @author Craig Berry
  * @since 5.0
  */
-@Beta
 @GwtIncompatible
+@ElementTypesAreNonnullByDefault
 public final class HostSpecifier {
 
   private final String canonicalForm;
@@ -70,9 +70,9 @@ private HostSpecifier(String canonicalForm) {
   public static HostSpecifier fromValid(String specifier) {
     // Verify that no port was specified, and strip optional brackets from
     // IPv6 literals.
-    final HostAndPort parsedHost = HostAndPort.fromString(specifier);
+    HostAndPort parsedHost = HostAndPort.fromString(specifier);
     Preconditions.checkArgument(!parsedHost.hasPort());
-    final String host = parsedHost.getHost();
+    String host = parsedHost.getHost();
 
     // Try to interpret the specifier as an IP address. Note we build
     // the address rather than using the .is* methods because we want to
@@ -92,7 +92,7 @@ public static HostSpecifier fromValid(String specifier) {
     // It is not any kind of IP address; must be a domain name or invalid.
 
     // TODO(user): different versions of this for different factories?
-    final InternetDomainName domain = InternetDomainName.from(host);
+    InternetDomainName domain = InternetDomainName.from(host);
 
     if (domain.hasPublicSuffix()) {
       return new HostSpecifier(domain.toString());
@@ -109,6 +109,7 @@ public static HostSpecifier fromValid(String specifier) {
    *
    * @throws ParseException if the specifier is not valid.
    */
+  @CanIgnoreReturnValue // TODO(b/219820829): consider removing
   public static HostSpecifier from(String specifier) throws ParseException {
     try {
       return fromValid(specifier);
@@ -129,7 +130,7 @@ public static HostSpecifier from(String specifier) throws ParseException {
    */
   public static boolean isValid(String specifier) {
     try {
-      fromValid(specifier);
+      HostSpecifier unused = fromValid(specifier);
       return true;
     } catch (IllegalArgumentException e) {
       return false;
@@ -137,13 +138,13 @@ public static boolean isValid(String specifier) {
   }
 
   @Override
-  public boolean equals(@NullableDecl Object other) {
+  public boolean equals(@CheckForNull Object other) {
     if (this == other) {
       return true;
     }
 
     if (other instanceof HostSpecifier) {
-      final HostSpecifier that = (HostSpecifier) other;
+      HostSpecifier that = (HostSpecifier) other;
       return this.canonicalForm.equals(that.canonicalForm);
     }
 
diff --git a/android/guava/src/com/google/common/net/HttpHeaders.java b/android/guava/src/com/google/common/net/HttpHeaders.java
index 2755a8fc9d2c..2ecbfaa8cb48 100644
--- a/android/guava/src/com/google/common/net/HttpHeaders.java
+++ b/android/guava/src/com/google/common/net/HttpHeaders.java
@@ -14,7 +14,6 @@
 
 package com.google.common.net;
 
-import com.google.common.annotations.Beta;
 import com.google.common.annotations.GwtCompatible;
 
 /**
@@ -32,6 +31,7 @@
  * @since 11.0
  */
 @GwtCompatible
+@ElementTypesAreNonnullByDefault
 public final class HttpHeaders {
   private HttpHeaders() {}
 
@@ -101,7 +101,6 @@ private HttpHeaders() {}
    *
    * @since 17.0
    */
-  @Beta
   public static final String FOLLOW_ONLY_WHEN_PRERENDER_SHOWN = "Follow-Only-When-Prerender-Shown";
   /** The HTTP {@code Host} header field name. */
   public static final String HOST = "Host";
@@ -200,6 +199,14 @@ private ReferrerPolicyValues() {}
   public static final String ACCESS_CONTROL_ALLOW_METHODS = "Access-Control-Allow-Methods";
   /** The HTTP {@code Access-Control-Allow-Origin} header field name. */
   public static final String ACCESS_CONTROL_ALLOW_ORIGIN = "Access-Control-Allow-Origin";
+  /**
+   * The HTTP <a href="https://wicg.github.io/private-network-access/#headers">{@code
+   * Access-Control-Allow-Private-Network}</a> header field name.
+   *
+   * @since 31.1
+   */
+  public static final String ACCESS_CONTROL_ALLOW_PRIVATE_NETWORK =
+      "Access-Control-Allow-Private-Network";
   /** The HTTP {@code Access-Control-Allow-Credentials} header field name. */
   public static final String ACCESS_CONTROL_ALLOW_CREDENTIALS = "Access-Control-Allow-Credentials";
   /** The HTTP {@code Access-Control-Expose-Headers} header field name. */
@@ -303,6 +310,12 @@ private ReferrerPolicyValues() {}
   public static final String LINK = "Link";
   /** The HTTP {@code Location} header field name. */
   public static final String LOCATION = "Location";
+  /**
+   * The HTTP {@code Keep-Alive} header field name.
+   *
+   * @since 31.0
+   */
+  public static final String KEEP_ALIVE = "Keep-Alive";
   /**
    * The HTTP <a href="https://googlechrome.github.io/OriginTrials/#header">{@code Origin-Trial}</a>
    * header field name.
@@ -350,7 +363,7 @@ private ReferrerPolicyValues() {}
    *
    * @since 27.1
    */
-  @Beta public static final String SOURCE_MAP = "SourceMap";
+  public static final String SOURCE_MAP = "SourceMap";
 
   /**
    * The HTTP <a href="http://tools.ietf.org/html/rfc6797#section-6.1">{@code
@@ -381,6 +394,45 @@ private ReferrerPolicyValues() {}
   public static final String DNT = "DNT";
   /** The HTTP {@code X-Content-Type-Options} header field name. */
   public static final String X_CONTENT_TYPE_OPTIONS = "X-Content-Type-Options";
+  /**
+   * The HTTP <a
+   * href="https://iabtechlab.com/wp-content/uploads/2019/06/VAST_4.2_final_june26.pdf">{@code
+   * X-Device-IP}</a> header field name. Header used for VAST requests to provide the IP address of
+   * the device on whose behalf the request is being made.
+   *
+   * @since 31.0
+   */
+  public static final String X_DEVICE_IP = "X-Device-IP";
+  /**
+   * The HTTP <a
+   * href="https://iabtechlab.com/wp-content/uploads/2019/06/VAST_4.2_final_june26.pdf">{@code
+   * X-Device-Referer}</a> header field name. Header used for VAST requests to provide the {@link
+   * #REFERER} header value that the on-behalf-of client would have used when making a request
+   * itself.
+   *
+   * @since 31.0
+   */
+  public static final String X_DEVICE_REFERER = "X-Device-Referer";
+  /**
+   * The HTTP <a
+   * href="https://iabtechlab.com/wp-content/uploads/2019/06/VAST_4.2_final_june26.pdf">{@code
+   * X-Device-Accept-Language}</a> header field name. Header used for VAST requests to provide the
+   * {@link #ACCEPT_LANGUAGE} header value that the on-behalf-of client would have used when making
+   * a request itself.
+   *
+   * @since 31.0
+   */
+  public static final String X_DEVICE_ACCEPT_LANGUAGE = "X-Device-Accept-Language";
+  /**
+   * The HTTP <a
+   * href="https://iabtechlab.com/wp-content/uploads/2019/06/VAST_4.2_final_june26.pdf">{@code
+   * X-Device-Requested-With}</a> header field name. Header used for VAST requests to provide the
+   * {@link #X_REQUESTED_WITH} header value that the on-behalf-of client would have used when making
+   * a request itself.
+   *
+   * @since 31.0
+   */
+  public static final String X_DEVICE_REQUESTED_WITH = "X-Device-Requested-With";
   /** The HTTP {@code X-Do-Not-Track} header field name. */
   public static final String X_DO_NOT_TRACK = "X-Do-Not-Track";
   /** The HTTP {@code X-Forwarded-For} header field name (superseded by {@code Forwarded}). */
@@ -409,14 +461,14 @@ private ReferrerPolicyValues() {}
    *
    * @since 15.0
    */
-  @Beta public static final String PUBLIC_KEY_PINS = "Public-Key-Pins";
+  public static final String PUBLIC_KEY_PINS = "Public-Key-Pins";
   /**
    * The HTTP <a href="http://tools.ietf.org/html/draft-evans-palmer-key-pinning">{@code
    * Public-Key-Pins-Report-Only}</a> header field name.
    *
    * @since 15.0
    */
-  @Beta public static final String PUBLIC_KEY_PINS_REPORT_ONLY = "Public-Key-Pins-Report-Only";
+  public static final String PUBLIC_KEY_PINS_REPORT_ONLY = "Public-Key-Pins-Report-Only";
   /**
    * The HTTP {@code X-Request-ID} header field name.
    *
@@ -436,7 +488,7 @@ private ReferrerPolicyValues() {}
    *
    * @since 24.1
    */
-  @Beta public static final String X_DOWNLOAD_OPTIONS = "X-Download-Options";
+  public static final String X_DOWNLOAD_OPTIONS = "X-Download-Options";
   /** The HTTP {@code X-XSS-Protection} header field name. */
   public static final String X_XSS_PROTECTION = "X-XSS-Protection";
   /**
@@ -486,6 +538,100 @@ private ReferrerPolicyValues() {}
    */
   public static final String X_MOZ = "X-Moz";
 
+  /**
+   * The HTTP <a
+   * href="https://developer.mozilla.org/en-US/docs/Web/HTTP/Headers/Device-Memory">{@code
+   * Device-Memory}</a> header field name.
+   *
+   * @since 31.0
+   */
+  public static final String DEVICE_MEMORY = "Device-Memory";
+
+  /**
+   * The HTTP <a href="https://developer.mozilla.org/en-US/docs/Web/HTTP/Headers/Downlink">{@code
+   * Downlink}</a> header field name.
+   *
+   * @since 31.0
+   */
+  public static final String DOWNLINK = "Downlink";
+
+  /**
+   * The HTTP <a href="https://developer.mozilla.org/en-US/docs/Web/HTTP/Headers/ECT">{@code
+   * ECT}</a> header field name.
+   *
+   * @since 31.0
+   */
+  public static final String ECT = "ECT";
+
+  /**
+   * The HTTP <a href="https://developer.mozilla.org/en-US/docs/Web/HTTP/Headers/RTT">{@code
+   * RTT}</a> header field name.
+   *
+   * @since 31.0
+   */
+  public static final String RTT = "RTT";
+
+  /**
+   * The HTTP <a href="https://developer.mozilla.org/en-US/docs/Web/HTTP/Headers/Save-Data">{@code
+   * Save-Data}</a> header field name.
+   *
+   * @since 31.0
+   */
+  public static final String SAVE_DATA = "Save-Data";
+
+  /**
+   * The HTTP <a
+   * href="https://developer.mozilla.org/en-US/docs/Web/HTTP/Headers/Viewport-Width">{@code
+   * Viewport-Width}</a> header field name.
+   *
+   * @since 31.0
+   */
+  public static final String VIEWPORT_WIDTH = "Viewport-Width";
+
+  /**
+   * The HTTP <a href="https://developer.mozilla.org/en-US/docs/Web/HTTP/Headers/Width">{@code
+   * Width}</a> header field name.
+   *
+   * @since 31.0
+   */
+  public static final String WIDTH = "Width";
+
+  /**
+   * The HTTP <a href="https://www.w3.org/TR/permissions-policy-1/">{@code Permissions-Policy}</a>
+   * header field name.
+   *
+   * @since 31.0
+   */
+  public static final String PERMISSIONS_POLICY = "Permissions-Policy";
+
+  /**
+   * The HTTP <a
+   * href="https://wicg.github.io/user-preference-media-features-headers/#sec-ch-prefers-color-scheme">{@code
+   * Sec-CH-Prefers-Color-Scheme}</a> header field name.
+   *
+   * <p>This header is experimental.
+   *
+   * @since 31.0
+   */
+  public static final String SEC_CH_PREFERS_COLOR_SCHEME = "Sec-CH-Prefers-Color-Scheme";
+
+  /**
+   * The HTTP <a
+   * href="https://www.rfc-editor.org/rfc/rfc8942#name-the-accept-ch-response-head">{@code
+   * Accept-CH}</a> header field name.
+   *
+   * @since 31.0
+   */
+  public static final String ACCEPT_CH = "Accept-CH";
+  /**
+   * The HTTP <a
+   * href="https://datatracker.ietf.org/doc/html/draft-davidben-http-client-hint-reliability-03.txt#section-3">{@code
+   * Critical-CH}</a> header field name.
+   *
+   * @since 31.0
+   */
+  public static final String CRITICAL_CH = "Critical-CH";
+
   /**
    * The HTTP <a href="https://wicg.github.io/ua-client-hints/#sec-ch-ua">{@code Sec-CH-UA}</a>
    * header field name.
@@ -494,47 +640,62 @@ private ReferrerPolicyValues() {}
    */
   public static final String SEC_CH_UA = "Sec-CH-UA";
   /**
-   * The HTTP <a href="https://wicg.github.io/ua-client-hints/#sec-ch-arch">{@code
+   * The HTTP <a href="https://wicg.github.io/ua-client-hints/#sec-ch-ua-arch">{@code
    * Sec-CH-UA-Arch}</a> header field name.
    *
    * @since 30.0
    */
   public static final String SEC_CH_UA_ARCH = "Sec-CH-UA-Arch";
   /**
-   * The HTTP <a href="https://wicg.github.io/ua-client-hints/#sec-ch-model">{@code
+   * The HTTP <a href="https://wicg.github.io/ua-client-hints/#sec-ch-ua-model">{@code
    * Sec-CH-UA-Model}</a> header field name.
    *
    * @since 30.0
    */
   public static final String SEC_CH_UA_MODEL = "Sec-CH-UA-Model";
   /**
-   * The HTTP <a href="https://wicg.github.io/ua-client-hints/#sec-ch-platform">{@code
+   * The HTTP <a href="https://wicg.github.io/ua-client-hints/#sec-ch-ua-platform">{@code
    * Sec-CH-UA-Platform}</a> header field name.
    *
    * @since 30.0
    */
   public static final String SEC_CH_UA_PLATFORM = "Sec-CH-UA-Platform";
   /**
-   * The HTTP <a href="https://wicg.github.io/ua-client-hints/#sec-ch-platform-version">{@code
+   * The HTTP <a href="https://wicg.github.io/ua-client-hints/#sec-ch-ua-platform-version">{@code
    * Sec-CH-UA-Platform-Version}</a> header field name.
    *
    * @since 30.0
    */
   public static final String SEC_CH_UA_PLATFORM_VERSION = "Sec-CH-UA-Platform-Version";
   /**
-   * The HTTP <a href="https://wicg.github.io/ua-client-hints/#sec-ch-full-version">{@code
+   * The HTTP <a href="https://wicg.github.io/ua-client-hints/#sec-ch-ua-full-version">{@code
    * Sec-CH-UA-Full-Version}</a> header field name.
    *
+   * @deprecated Prefer {@link SEC_CH_UA_FULL_VERSION_LIST}.
    * @since 30.0
    */
-  public static final String SEC_CH_UA_FULL_VERSION = "Sec-CH-UA-Full-Version";
+  @Deprecated public static final String SEC_CH_UA_FULL_VERSION = "Sec-CH-UA-Full-Version";
   /**
-   * The HTTP <a href="https://wicg.github.io/ua-client-hints/#sec-ch-mobile">{@code
+   * The HTTP <a href="https://wicg.github.io/ua-client-hints/#sec-ch-ua-full-version-list">{@code
+   * Sec-CH-UA-Full-Version}</a> header field name.
+   *
+   * @since 31.1
+   */
+  public static final String SEC_CH_UA_FULL_VERSION_LIST = "Sec-CH-UA-Full-Version-List";
+  /**
+   * The HTTP <a href="https://wicg.github.io/ua-client-hints/#sec-ch-ua-mobile">{@code
    * Sec-CH-UA-Mobile}</a> header field name.
    *
    * @since 30.0
    */
   public static final String SEC_CH_UA_MOBILE = "Sec-CH-UA-Mobile";
+  /**
+   * The HTTP <a href="https://wicg.github.io/ua-client-hints/#sec-ch-ua-bitness">{@code
+   * Sec-CH-UA-Bitness}</a> header field name.
+   *
+   * @since 31.0
+   */
+  public static final String SEC_CH_UA_BITNESS = "Sec-CH-UA-Bitness";
 
   /**
    * The HTTP <a href="https://w3c.github.io/webappsec-fetch-metadata/">{@code Sec-Fetch-Dest}</a>
diff --git a/android/guava/src/com/google/common/net/InetAddresses.java b/android/guava/src/com/google/common/net/InetAddresses.java
index a4a16e2b36ea..d3e68db8ac6f 100644
--- a/android/guava/src/com/google/common/net/InetAddresses.java
+++ b/android/guava/src/com/google/common/net/InetAddresses.java
@@ -17,13 +17,13 @@
 import static com.google.common.base.Preconditions.checkArgument;
 import static com.google.common.base.Preconditions.checkNotNull;
 
-import com.google.common.annotations.Beta;
 import com.google.common.annotations.GwtIncompatible;
 import com.google.common.base.CharMatcher;
 import com.google.common.base.MoreObjects;
 import com.google.common.hash.Hashing;
 import com.google.common.io.ByteStreams;
 import com.google.common.primitives.Ints;
+import com.google.errorprone.annotations.CanIgnoreReturnValue;
 import java.math.BigInteger;
 import java.net.Inet4Address;
 import java.net.Inet6Address;
@@ -32,7 +32,7 @@
 import java.nio.ByteBuffer;
 import java.util.Arrays;
 import java.util.Locale;
-import org.checkerframework.checker.nullness.compatqual.NullableDecl;
+import javax.annotation.CheckForNull;
 
 /**
  * Static utility methods pertaining to {@link InetAddress} instances.
@@ -95,8 +95,8 @@
  * @author Erik Kline
  * @since 5.0
  */
-@Beta
 @GwtIncompatible
+@ElementTypesAreNonnullByDefault
 public final class InetAddresses {
   private static final int IPV4_PART_COUNT = 4;
   private static final int IPV6_PART_COUNT = 8;
@@ -133,11 +133,17 @@ private static Inet4Address getInet4Address(byte[] bytes) {
    *
    * <p>Anything after a {@code %} in an IPv6 address is ignored (assumed to be a Scope ID).
    *
+   * <p>This method accepts non-ASCII digits, for example {@code "１９２.１６８.０.１"} (those are fullwidth
+   * characters). That is consistent with {@link InetAddress}, but not with various RFCs. If you
+   * want to accept ASCII digits only, you can use something like {@code
+   * CharMatcher.ascii().matchesAllOf(ipString)}.
+   *
    * @param ipString {@code String} containing an IPv4 or IPv6 string literal, e.g. {@code
    *     "192.168.0.1"} or {@code "2001:db8::1"}
    * @return {@link InetAddress} representing the argument
    * @throws IllegalArgumentException if the argument is not a valid IP string literal
    */
+  @CanIgnoreReturnValue // TODO(b/219820829): consider removing
   public static InetAddress forString(String ipString) {
     byte[] addr = ipStringToBytes(ipString);
 
@@ -153,6 +159,11 @@ public static InetAddress forString(String ipString) {
    * Returns {@code true} if the supplied string is a valid IP string literal, {@code false}
    * otherwise.
    *
+   * <p>This method accepts non-ASCII digits, for example {@code "１９２.１６８.０.１"} (those are fullwidth
+   * characters). That is consistent with {@link InetAddress}, but not with various RFCs. If you
+   * want to accept ASCII digits only, you can use something like {@code
+   * CharMatcher.ascii().matchesAllOf(ipString)}.
+   *
    * @param ipString {@code String} to evaluated as an IP string literal
    * @return {@code true} if the argument is a valid IP string literal
    */
@@ -161,8 +172,9 @@ public static boolean isInetAddress(String ipString) {
   }
 
   /** Returns {@code null} if unable to parse into a {@code byte[]}. */
-  @NullableDecl
-  private static byte[] ipStringToBytes(String ipString) {
+  @CheckForNull
+  private static byte[] ipStringToBytes(String ipStringParam) {
+    String ipString = ipStringParam;
     // Make a first pass to categorize the characters in this string.
     boolean hasColon = false;
     boolean hasDot = false;
@@ -205,7 +217,7 @@ private static byte[] ipStringToBytes(String ipString) {
     return null;
   }
 
-  @NullableDecl
+  @CheckForNull
   private static byte[] textToNumericFormatV4(String ipString) {
     if (IPV4_DELIMITER_MATCHER.countIn(ipString) + 1 != IPV4_PART_COUNT) {
       return null; // Wrong number of parts
@@ -231,7 +243,7 @@ private static byte[] textToNumericFormatV4(String ipString) {
     return bytes;
   }
 
-  @NullableDecl
+  @CheckForNull
   private static byte[] textToNumericFormatV6(String ipString) {
     // An address can have [2..8] colons.
     int delimiterCount = IPV6_DELIMITER_MATCHER.countIn(ipString);
@@ -302,7 +314,7 @@ private static byte[] textToNumericFormatV6(String ipString) {
     return rawBytes.array();
   }
 
-  @NullableDecl
+  @CheckForNull
   private static String convertDottedQuadToHex(String ipString) {
     int lastColon = ipString.lastIndexOf(':');
     String initialPart = ipString.substring(0, lastColon + 1);
@@ -500,10 +512,15 @@ public static String toUriString(InetAddress ip) {
    * Returns an InetAddress representing the literal IPv4 or IPv6 host portion of a URL, encoded in
    * the format specified by RFC 3986 section 3.2.2.
    *
-   * <p>This function is similar to {@link InetAddresses#forString(String)}, however, it requires
-   * that IPv6 addresses are surrounded by square brackets.
+   * <p>This method is similar to {@link InetAddresses#forString(String)}, however, it requires that
+   * IPv6 addresses are surrounded by square brackets.
+   *
+   * <p>This method is the inverse of {@link InetAddresses#toUriString(java.net.InetAddress)}.
    *
-   * <p>This function is the inverse of {@link InetAddresses#toUriString(java.net.InetAddress)}.
+   * <p>This method accepts non-ASCII digits, for example {@code "１９２.１６８.０.１"} (those are fullwidth
+   * characters). That is consistent with {@link InetAddress}, but not with various RFCs. If you
+   * want to accept ASCII digits only, you can use something like {@code
+   * CharMatcher.ascii().matchesAllOf(ipString)}.
    *
    * @param hostAddr A RFC 3986 section 3.2.2 encoded IPv4 or IPv6 address
    * @return an InetAddress representing the address in {@code hostAddr}
@@ -519,7 +536,7 @@ public static InetAddress forUriString(String hostAddr) {
     return addr;
   }
 
-  @NullableDecl
+  @CheckForNull
   private static InetAddress forUriStringNoThrow(String hostAddr) {
     checkNotNull(hostAddr);
 
@@ -547,6 +564,11 @@ private static InetAddress forUriStringNoThrow(String hostAddr) {
    * Returns {@code true} if the supplied string is a valid URI IP string literal, {@code false}
    * otherwise.
    *
+   * <p>This method accepts non-ASCII digits, for example {@code "１９２.１６８.０.１"} (those are fullwidth
+   * characters). That is consistent with {@link InetAddress}, but not with various RFCs. If you
+   * want to accept ASCII digits only, you can use something like {@code
+   * CharMatcher.ascii().matchesAllOf(ipString)}.
+   *
    * @param ipString {@code String} to evaluated as an IP URI host string literal
    * @return {@code true} if the argument is a valid IP URI host
    */
@@ -645,7 +667,6 @@ public static Inet4Address get6to4IPv4Address(Inet6Address ip) {
    *
    * @since 5.0
    */
-  @Beta
   public static final class TeredoInfo {
     private final Inet4Address server;
     private final Inet4Address client;
@@ -663,7 +684,7 @@ public static final class TeredoInfo {
      */
     // TODO: why is this public?
     public TeredoInfo(
-        @NullableDecl Inet4Address server, @NullableDecl Inet4Address client, int port, int flags) {
+        @CheckForNull Inet4Address server, @CheckForNull Inet4Address client, int port, int flags) {
       checkArgument(
           (port >= 0) && (port <= 0xffff), "port '%s' is out of range (0 <= port <= 0xffff)", port);
       checkArgument(
@@ -842,6 +863,10 @@ public static Inet4Address getEmbeddedIPv4ClientAddress(Inet6Address ip) {
    * obscure {@link Inet6Address} methods, but it would be unwise to depend on such a
    * poorly-documented feature.)
    *
+   * <p>This method accepts non-ASCII digits. That is consistent with {@link InetAddress}, but not
+   * with various RFCs. If you want to accept ASCII digits only, you can use something like {@code
+   * CharMatcher.ascii().matchesAllOf(ipString)}.
+   *
    * @param ipString {@code String} to be examined for embedded IPv4-mapped IPv6 address format
    * @return {@code true} if the argument is a valid "mapped" address
    * @since 10.0
@@ -869,7 +894,7 @@ public static boolean isMappedIPv4Address(String ipString) {
    *
    * <p>HACK: As long as applications continue to use IPv4 addresses for indexing into tables,
    * accounting, et cetera, it may be necessary to <b>coerce</b> IPv6 addresses into IPv4 addresses.
-   * This function does so by hashing 64 bits of the IPv6 address into {@code 224.0.0.0/3} (64 bits
+   * This method does so by hashing 64 bits of the IPv6 address into {@code 224.0.0.0/3} (64 bits
    * into 29 bits):
    *
    * <ul>
@@ -879,7 +904,7 @@ public static boolean isMappedIPv4Address(String ipString) {
    *
    * <p>A "coerced" IPv4 address is equivalent to itself.
    *
-   * <p>NOTE: This function is failsafe for security purposes: ALL IPv6 addresses (except localhost
+   * <p>NOTE: This method is failsafe for security purposes: ALL IPv6 addresses (except localhost
    * (::1)) are hashed to avoid the security risk associated with extracting an embedded IPv4
    * address that might permit elevated privileges.
    *
@@ -917,7 +942,7 @@ public static Inet4Address getCoercedIPv4Address(InetAddress ip) {
     }
 
     // Many strategies for hashing are possible. This might suffice for now.
-    int coercedHash = Hashing.murmur3_32().hashLong(addressAsLong).asInt();
+    int coercedHash = Hashing.murmur3_32_fixed().hashLong(addressAsLong).asInt();
 
     // Squash into 224/4 Multicast and 240/4 Reserved space (i.e. 224/3).
     coercedHash |= 0xe0000000;
@@ -1115,8 +1140,8 @@ public static InetAddress increment(InetAddress address) {
    */
   public static boolean isMaximum(InetAddress address) {
     byte[] addr = address.getAddress();
-    for (int i = 0; i < addr.length; i++) {
-      if (addr[i] != (byte) 0xff) {
+    for (byte b : addr) {
+      if (b != (byte) 0xff) {
         return false;
       }
     }
diff --git a/android/guava/src/com/google/common/net/InternetDomainName.java b/android/guava/src/com/google/common/net/InternetDomainName.java
index 4cc505696820..d71a9d5c3c6c 100644
--- a/android/guava/src/com/google/common/net/InternetDomainName.java
+++ b/android/guava/src/com/google/common/net/InternetDomainName.java
@@ -18,7 +18,6 @@
 import static com.google.common.base.Preconditions.checkNotNull;
 import static com.google.common.base.Preconditions.checkState;
 
-import com.google.common.annotations.Beta;
 import com.google.common.annotations.GwtCompatible;
 import com.google.common.base.Ascii;
 import com.google.common.base.CharMatcher;
@@ -26,11 +25,12 @@
 import com.google.common.base.Optional;
 import com.google.common.base.Splitter;
 import com.google.common.collect.ImmutableList;
+import com.google.errorprone.annotations.CanIgnoreReturnValue;
 import com.google.errorprone.annotations.Immutable;
 import com.google.thirdparty.publicsuffix.PublicSuffixPatterns;
 import com.google.thirdparty.publicsuffix.PublicSuffixType;
 import java.util.List;
-import org.checkerframework.checker.nullness.compatqual.NullableDecl;
+import javax.annotation.CheckForNull;
 
 /**
  * An immutable well-formed internet domain name, such as {@code com} or {@code foo.co.uk}. Only
@@ -71,9 +71,9 @@
  * @author Catherine Berry
  * @since 5.0
  */
-@Beta
 @GwtCompatible(emulated = true)
 @Immutable
+@ElementTypesAreNonnullByDefault
 public final class InternetDomainName {
 
   private static final CharMatcher DOTS_MATCHER = CharMatcher.anyOf(".\u3002\uFF0E\uFF61");
@@ -162,7 +162,7 @@ public final class InternetDomainName {
    * Otherwise, it finds the first suffix of any type.
    */
   private int findSuffixOfType(Optional<PublicSuffixType> desiredType) {
-    final int partsSize = parts.size();
+    int partsSize = parts.size();
 
     for (int i = 0; i < partsSize; i++) {
       String ancestorName = DOT_JOINER.join(parts.subList(i, partsSize));
@@ -205,6 +205,7 @@ private int findSuffixOfType(Optional<PublicSuffixType> desiredType) {
    *     {@link #isValid}
    * @since 10.0 (previously named {@code fromLenient})
    */
+  @CanIgnoreReturnValue // TODO(b/219820829): consider removing
   public static InternetDomainName from(String domain) {
     return new InternetDomainName(checkNotNull(domain));
   }
@@ -216,7 +217,7 @@ public static InternetDomainName from(String domain) {
    * @return Is the domain name syntactically valid?
    */
   private static boolean validateSyntax(List<String> parts) {
-    final int lastIndex = parts.size() - 1;
+    int lastIndex = parts.size() - 1;
 
     // Validate the last part specially, as it has different syntax rules.
 
@@ -353,6 +354,7 @@ public boolean hasPublicSuffix() {
    *
    * @since 6.0
    */
+  @CheckForNull
   public InternetDomainName publicSuffix() {
     return hasPublicSuffix() ? ancestor(publicSuffixIndex) : null;
   }
@@ -461,6 +463,7 @@ public boolean hasRegistrySuffix() {
    *
    * @since 23.3
    */
+  @CheckForNull
   public InternetDomainName registrySuffix() {
     return hasRegistrySuffix() ? ancestor(registrySuffixIndex) : null;
   }
@@ -581,7 +584,7 @@ public InternetDomainName child(String leftParts) {
    */
   public static boolean isValid(String name) {
     try {
-      from(name);
+      InternetDomainName unused = from(name);
       return true;
     } catch (IllegalArgumentException e) {
       return false;
@@ -621,7 +624,7 @@ public String toString() {
    * version of the same domain name would not be considered equal.
    */
   @Override
-  public boolean equals(@NullableDecl Object object) {
+  public boolean equals(@CheckForNull Object object) {
     if (object == this) {
       return true;
     }
diff --git a/android/guava/src/com/google/common/net/MediaType.java b/android/guava/src/com/google/common/net/MediaType.java
index a5b710f85315..a713d0b17ae5 100644
--- a/android/guava/src/com/google/common/net/MediaType.java
+++ b/android/guava/src/com/google/common/net/MediaType.java
@@ -21,11 +21,9 @@
 import static com.google.common.base.Preconditions.checkNotNull;
 import static com.google.common.base.Preconditions.checkState;
 
-import com.google.common.annotations.Beta;
 import com.google.common.annotations.GwtCompatible;
 import com.google.common.base.Ascii;
 import com.google.common.base.CharMatcher;
-import com.google.common.base.Function;
 import com.google.common.base.Joiner;
 import com.google.common.base.Joiner.MapJoiner;
 import com.google.common.base.MoreObjects;
@@ -37,15 +35,15 @@
 import com.google.common.collect.Maps;
 import com.google.common.collect.Multimap;
 import com.google.common.collect.Multimaps;
+import com.google.errorprone.annotations.CanIgnoreReturnValue;
 import com.google.errorprone.annotations.Immutable;
 import com.google.errorprone.annotations.concurrent.LazyInit;
 import java.nio.charset.Charset;
 import java.nio.charset.IllegalCharsetNameException;
 import java.nio.charset.UnsupportedCharsetException;
-import java.util.Collection;
 import java.util.Map;
 import java.util.Map.Entry;
-import org.checkerframework.checker.nullness.compatqual.NullableDecl;
+import javax.annotation.CheckForNull;
 
 /**
  * Represents an <a href="http://en.wikipedia.org/wiki/Internet_media_type">Internet Media Type</a>
@@ -72,9 +70,9 @@
  * @since 12.0
  * @author Gregory Kick
  */
-@Beta
 @GwtCompatible
 @Immutable
+@ElementTypesAreNonnullByDefault
 public final class MediaType {
   private static final String CHARSET_ATTRIBUTE = "charset";
   private static final ImmutableListMultimap<String, String> UTF_8_CONSTANT_PARAMETERS =
@@ -763,11 +761,11 @@ private static MediaType addKnownType(MediaType mediaType) {
   private final String subtype;
   private final ImmutableListMultimap<String, String> parameters;
 
-  @LazyInit private String toString;
+  @LazyInit @CheckForNull private String toString;
 
   @LazyInit private int hashCode;
 
-  @LazyInit private Optional<Charset> parsedCharset;
+  @LazyInit @CheckForNull private Optional<Charset> parsedCharset;
 
   private MediaType(String type, String subtype, ImmutableListMultimap<String, String> parameters) {
     this.type = type;
@@ -791,14 +789,7 @@ public ImmutableListMultimap<String, String> parameters() {
   }
 
   private Map<String, ImmutableMultiset<String>> parametersAsMap() {
-    return Maps.transformValues(
-        parameters.asMap(),
-        new Function<Collection<String>, ImmutableMultiset<String>>() {
-          @Override
-          public ImmutableMultiset<String> apply(Collection<String> input) {
-            return ImmutableMultiset.copyOf(input);
-          }
-        });
+    return Maps.transformValues(parameters.asMap(), ImmutableMultiset::copyOf);
   }
 
   /**
@@ -1048,6 +1039,7 @@ private static String normalizeParameterValue(String attribute, String value) {
    *
    * @throws IllegalArgumentException if the input is not parsable
    */
+  @CanIgnoreReturnValue // TODO(b/219820829): consider removing
   public static MediaType parse(String input) {
     checkNotNull(input);
     Tokenizer tokenizer = new Tokenizer(input);
@@ -1062,7 +1054,7 @@ public static MediaType parse(String input) {
         tokenizer.consumeTokenIfPresent(LINEAR_WHITE_SPACE);
         String attribute = tokenizer.consumeToken(TOKEN_MATCHER);
         tokenizer.consumeCharacter('=');
-        final String value;
+        String value;
         if ('"' == tokenizer.previewChar()) {
           tokenizer.consumeCharacter('"');
           StringBuilder valueBuilder = new StringBuilder();
@@ -1095,6 +1087,7 @@ private static final class Tokenizer {
       this.input = input;
     }
 
+    @CanIgnoreReturnValue
     String consumeTokenIfPresent(CharMatcher matcher) {
       checkState(hasMore());
       int startPosition = position;
@@ -1117,6 +1110,7 @@ char consumeCharacter(CharMatcher matcher) {
       return c;
     }
 
+    @CanIgnoreReturnValue
     char consumeCharacter(char c) {
       checkState(hasMore());
       checkState(previewChar() == c);
@@ -1135,7 +1129,7 @@ boolean hasMore() {
   }
 
   @Override
-  public boolean equals(@NullableDecl Object obj) {
+  public boolean equals(@CheckForNull Object obj) {
     if (obj == this) {
       return true;
     } else if (obj instanceof MediaType) {
@@ -1184,14 +1178,10 @@ private String computeToString() {
       Multimap<String, String> quotedParameters =
           Multimaps.transformValues(
               parameters,
-              new Function<String, String>() {
-                @Override
-                public String apply(String value) {
-                  return (TOKEN_MATCHER.matchesAllOf(value) && !value.isEmpty())
+              (String value) ->
+                  (TOKEN_MATCHER.matchesAllOf(value) && !value.isEmpty())
                       ? value
-                      : escapeAndQuote(value);
-                }
-              });
+                      : escapeAndQuote(value));
       PARAMETER_JOINER.appendTo(builder, quotedParameters.entries());
     }
     return builder.toString();
diff --git a/android/guava/src/com/google/common/net/ParametricNullness.java b/android/guava/src/com/google/common/net/ParametricNullness.java
new file mode 100644
index 000000000000..1ad2e27c0f4f
--- /dev/null
+++ b/android/guava/src/com/google/common/net/ParametricNullness.java
@@ -0,0 +1,52 @@
+/*
+ * Copyright (C) 2021 The Guava Authors
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package com.google.common.net;
+
+import static java.lang.annotation.ElementType.FIELD;
+import static java.lang.annotation.ElementType.METHOD;
+import static java.lang.annotation.ElementType.PARAMETER;
+import static java.lang.annotation.RetentionPolicy.RUNTIME;
+
+import com.google.common.annotations.GwtCompatible;
+import java.lang.annotation.Retention;
+import java.lang.annotation.Target;
+
+/**
+ * Marks a "top-level" type-variable usage as the closest we can get to "non-nullable when
+ * non-nullable; nullable when nullable" (like the Android <a
+ * href="https://android.googlesource.com/platform/libcore/+/master/luni/src/main/java/libcore/util/NullFromTypeParam.java">{@code
+ * NullFromTypeParam}</a>).
+ *
+ * <p>Consumers of this annotation include:
+ *
+ * <ul>
+ *   <li>Kotlin, for which it makes the type-variable usage (a) a Kotlin platform type when the type
+ *       argument is non-nullable and (b) nullable when the type argument is nullable. We use this
+ *       to "undo" {@link ElementTypesAreNonnullByDefault}.
+ *   <li><a href="https://developers.google.com/j2objc">J2ObjC</a>
+ *   <li>{@code NullPointerTester}, at least in the Android backport (where the type-use annotations
+ *       {@code NullPointerTester} would need are not available) and in case of <a
+ *       href="https://bugs.openjdk.java.net/browse/JDK-8202469">JDK-8202469</a>
+ * </ul>
+ *
+ */
+@GwtCompatible
+@Retention(RUNTIME)
+@Target({FIELD, METHOD, PARAMETER})
+@javax.annotation.meta.TypeQualifierNickname
+@javax.annotation.Nonnull(when = javax.annotation.meta.When.UNKNOWN)
+@interface ParametricNullness {}
diff --git a/android/guava/src/com/google/common/net/PercentEscaper.java b/android/guava/src/com/google/common/net/PercentEscaper.java
index 554d04d78d7a..92901473123c 100644
--- a/android/guava/src/com/google/common/net/PercentEscaper.java
+++ b/android/guava/src/com/google/common/net/PercentEscaper.java
@@ -16,9 +16,9 @@
 
 import static com.google.common.base.Preconditions.checkNotNull;
 
-import com.google.common.annotations.Beta;
 import com.google.common.annotations.GwtCompatible;
 import com.google.common.escape.UnicodeEscaper;
+import javax.annotation.CheckForNull;
 
 /**
  * A {@code UnicodeEscaper} that escapes some set of Java characters using a UTF-8 based percent
@@ -49,8 +49,8 @@
  * @author David Beaumont
  * @since 15.0
  */
-@Beta
 @GwtCompatible
+@ElementTypesAreNonnullByDefault
 public final class PercentEscaper extends UnicodeEscaper {
 
   // In some escapers spaces are escaped to '+'
@@ -155,6 +155,7 @@ public String escape(String s) {
 
   /** Escapes the given Unicode code point in UTF-8. */
   @Override
+  @CheckForNull
   protected char[] escape(int cp) {
     // We should never get negative values here but if we do it will throw an
     // IndexOutOfBoundsException, so at least it will get spotted.
diff --git a/android/guava/src/com/google/common/net/UrlEscapers.java b/android/guava/src/com/google/common/net/UrlEscapers.java
index 28da2e337753..c7e15efc6d91 100644
--- a/android/guava/src/com/google/common/net/UrlEscapers.java
+++ b/android/guava/src/com/google/common/net/UrlEscapers.java
@@ -29,6 +29,7 @@
  * @since 15.0
  */
 @GwtCompatible
+@ElementTypesAreNonnullByDefault
 public final class UrlEscapers {
   private UrlEscapers() {}
 
diff --git a/android/guava/src/com/google/common/net/package-info.java b/android/guava/src/com/google/common/net/package-info.java
index d9db26637974..d55642d9431b 100644
--- a/android/guava/src/com/google/common/net/package-info.java
+++ b/android/guava/src/com/google/common/net/package-info.java
@@ -21,7 +21,9 @@
  *
  * @author Craig Berry
  */
+@CheckReturnValue
 @ParametersAreNonnullByDefault
 package com.google.common.net;
 
+import com.google.errorprone.annotations.CheckReturnValue;
 import javax.annotation.ParametersAreNonnullByDefault;
diff --git a/android/guava/src/com/google/common/primitives/Booleans.java b/android/guava/src/com/google/common/primitives/Booleans.java
index 787766db87e1..522049bfe3eb 100644
--- a/android/guava/src/com/google/common/primitives/Booleans.java
+++ b/android/guava/src/com/google/common/primitives/Booleans.java
@@ -29,7 +29,7 @@
 import java.util.Comparator;
 import java.util.List;
 import java.util.RandomAccess;
-import org.checkerframework.checker.nullness.compatqual.NullableDecl;
+import javax.annotation.CheckForNull;
 
 /**
  * Static utility methods pertaining to {@code boolean} primitives, that are not already found in
@@ -42,6 +42,7 @@
  * @since 1.0
  */
 @GwtCompatible
+@ElementTypesAreNonnullByDefault
 public final class Booleans {
   private Booleans() {}
 
@@ -408,14 +409,14 @@ public Boolean get(int index) {
     }
 
     @Override
-    public boolean contains(Object target) {
+    public boolean contains(@CheckForNull Object target) {
       // Overridden to prevent a ton of boxing
       return (target instanceof Boolean)
           && Booleans.indexOf(array, (Boolean) target, start, end) != -1;
     }
 
     @Override
-    public int indexOf(Object target) {
+    public int indexOf(@CheckForNull Object target) {
       // Overridden to prevent a ton of boxing
       if (target instanceof Boolean) {
         int i = Booleans.indexOf(array, (Boolean) target, start, end);
@@ -427,7 +428,7 @@ public int indexOf(Object target) {
     }
 
     @Override
-    public int lastIndexOf(Object target) {
+    public int lastIndexOf(@CheckForNull Object target) {
       // Overridden to prevent a ton of boxing
       if (target instanceof Boolean) {
         int i = Booleans.lastIndexOf(array, (Boolean) target, start, end);
@@ -458,7 +459,7 @@ public List<Boolean> subList(int fromIndex, int toIndex) {
     }
 
     @Override
-    public boolean equals(@NullableDecl Object object) {
+    public boolean equals(@CheckForNull Object object) {
       if (object == this) {
         return true;
       }
diff --git a/android/guava/src/com/google/common/primitives/Bytes.java b/android/guava/src/com/google/common/primitives/Bytes.java
index 1071a0e7b896..62997f34aac7 100644
--- a/android/guava/src/com/google/common/primitives/Bytes.java
+++ b/android/guava/src/com/google/common/primitives/Bytes.java
@@ -27,7 +27,7 @@
 import java.util.Collections;
 import java.util.List;
 import java.util.RandomAccess;
-import org.checkerframework.checker.nullness.compatqual.NullableDecl;
+import javax.annotation.CheckForNull;
 
 /**
  * Static utility methods pertaining to {@code byte} primitives, that are not already found in
@@ -44,6 +44,7 @@
 // TODO(kevinb): how to prevent warning on UnsignedBytes when building GWT
 // javadoc?
 @GwtCompatible
+@ElementTypesAreNonnullByDefault
 public final class Bytes {
   private Bytes() {}
 
@@ -270,13 +271,13 @@ public Byte get(int index) {
     }
 
     @Override
-    public boolean contains(Object target) {
+    public boolean contains(@CheckForNull Object target) {
       // Overridden to prevent a ton of boxing
       return (target instanceof Byte) && Bytes.indexOf(array, (Byte) target, start, end) != -1;
     }
 
     @Override
-    public int indexOf(Object target) {
+    public int indexOf(@CheckForNull Object target) {
       // Overridden to prevent a ton of boxing
       if (target instanceof Byte) {
         int i = Bytes.indexOf(array, (Byte) target, start, end);
@@ -288,7 +289,7 @@ public int indexOf(Object target) {
     }
 
     @Override
-    public int lastIndexOf(Object target) {
+    public int lastIndexOf(@CheckForNull Object target) {
       // Overridden to prevent a ton of boxing
       if (target instanceof Byte) {
         int i = Bytes.lastIndexOf(array, (Byte) target, start, end);
@@ -319,7 +320,7 @@ public List<Byte> subList(int fromIndex, int toIndex) {
     }
 
     @Override
-    public boolean equals(@NullableDecl Object object) {
+    public boolean equals(@CheckForNull Object object) {
       if (object == this) {
         return true;
       }
diff --git a/android/guava/src/com/google/common/primitives/Chars.java b/android/guava/src/com/google/common/primitives/Chars.java
index 07fc62f62416..4a2e3a3449cb 100644
--- a/android/guava/src/com/google/common/primitives/Chars.java
+++ b/android/guava/src/com/google/common/primitives/Chars.java
@@ -30,7 +30,7 @@
 import java.util.Comparator;
 import java.util.List;
 import java.util.RandomAccess;
-import org.checkerframework.checker.nullness.compatqual.NullableDecl;
+import javax.annotation.CheckForNull;
 
 /**
  * Static utility methods pertaining to {@code char} primitives, that are not already found in
@@ -46,6 +46,7 @@
  * @since 1.0
  */
 @GwtCompatible(emulated = true)
+@ElementTypesAreNonnullByDefault
 public final class Chars {
   private Chars() {}
 
@@ -540,14 +541,14 @@ public Character get(int index) {
     }
 
     @Override
-    public boolean contains(Object target) {
+    public boolean contains(@CheckForNull Object target) {
       // Overridden to prevent a ton of boxing
       return (target instanceof Character)
           && Chars.indexOf(array, (Character) target, start, end) != -1;
     }
 
     @Override
-    public int indexOf(Object target) {
+    public int indexOf(@CheckForNull Object target) {
       // Overridden to prevent a ton of boxing
       if (target instanceof Character) {
         int i = Chars.indexOf(array, (Character) target, start, end);
@@ -559,7 +560,7 @@ public int indexOf(Object target) {
     }
 
     @Override
-    public int lastIndexOf(Object target) {
+    public int lastIndexOf(@CheckForNull Object target) {
       // Overridden to prevent a ton of boxing
       if (target instanceof Character) {
         int i = Chars.lastIndexOf(array, (Character) target, start, end);
@@ -590,7 +591,7 @@ public List<Character> subList(int fromIndex, int toIndex) {
     }
 
     @Override
-    public boolean equals(@NullableDecl Object object) {
+    public boolean equals(@CheckForNull Object object) {
       if (object == this) {
         return true;
       }
diff --git a/android/guava/src/com/google/common/primitives/Doubles.java b/android/guava/src/com/google/common/primitives/Doubles.java
index a886fe92519b..ce5df2e394db 100644
--- a/android/guava/src/com/google/common/primitives/Doubles.java
+++ b/android/guava/src/com/google/common/primitives/Doubles.java
@@ -34,7 +34,7 @@
 import java.util.Comparator;
 import java.util.List;
 import java.util.RandomAccess;
-import org.checkerframework.checker.nullness.compatqual.NullableDecl;
+import javax.annotation.CheckForNull;
 
 /**
  * Static utility methods pertaining to {@code double} primitives, that are not already found in
@@ -47,6 +47,7 @@
  * @since 1.0
  */
 @GwtCompatible(emulated = true)
+@ElementTypesAreNonnullByDefault
 public final class Doubles extends DoublesMethodsForWeb {
   private Doubles() {}
 
@@ -553,14 +554,14 @@ public Double get(int index) {
     }
 
     @Override
-    public boolean contains(Object target) {
+    public boolean contains(@CheckForNull Object target) {
       // Overridden to prevent a ton of boxing
       return (target instanceof Double)
           && Doubles.indexOf(array, (Double) target, start, end) != -1;
     }
 
     @Override
-    public int indexOf(Object target) {
+    public int indexOf(@CheckForNull Object target) {
       // Overridden to prevent a ton of boxing
       if (target instanceof Double) {
         int i = Doubles.indexOf(array, (Double) target, start, end);
@@ -572,7 +573,7 @@ public int indexOf(Object target) {
     }
 
     @Override
-    public int lastIndexOf(Object target) {
+    public int lastIndexOf(@CheckForNull Object target) {
       // Overridden to prevent a ton of boxing
       if (target instanceof Double) {
         int i = Doubles.lastIndexOf(array, (Double) target, start, end);
@@ -603,7 +604,7 @@ public List<Double> subList(int fromIndex, int toIndex) {
     }
 
     @Override
-    public boolean equals(@NullableDecl Object object) {
+    public boolean equals(@CheckForNull Object object) {
       if (object == this) {
         return true;
       }
@@ -702,7 +703,7 @@ public String toString() {
    */
   @Beta
   @GwtIncompatible // regular expressions
-  @NullableDecl
+  @CheckForNull
   public static Double tryParse(String string) {
     if (FLOATING_POINT_PATTERN.matcher(string).matches()) {
       // TODO(lowasser): could be potentially optimized, but only with
diff --git a/android/guava/src/com/google/common/primitives/DoublesMethodsForWeb.java b/android/guava/src/com/google/common/primitives/DoublesMethodsForWeb.java
index 04d96512211d..949cbe0f5a6b 100644
--- a/android/guava/src/com/google/common/primitives/DoublesMethodsForWeb.java
+++ b/android/guava/src/com/google/common/primitives/DoublesMethodsForWeb.java
@@ -21,4 +21,5 @@
  * version.
  */
 @GwtCompatible(emulated = true)
+@ElementTypesAreNonnullByDefault
 abstract class DoublesMethodsForWeb {}
diff --git a/android/guava/src/com/google/common/primitives/ElementTypesAreNonnullByDefault.java b/android/guava/src/com/google/common/primitives/ElementTypesAreNonnullByDefault.java
new file mode 100644
index 000000000000..44f6869c7cda
--- /dev/null
+++ b/android/guava/src/com/google/common/primitives/ElementTypesAreNonnullByDefault.java
@@ -0,0 +1,41 @@
+/*
+ * Copyright (C) 2021 The Guava Authors
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package com.google.common.primitives;
+
+import static java.lang.annotation.ElementType.FIELD;
+import static java.lang.annotation.ElementType.METHOD;
+import static java.lang.annotation.ElementType.PARAMETER;
+import static java.lang.annotation.ElementType.TYPE;
+import static java.lang.annotation.RetentionPolicy.RUNTIME;
+
+import com.google.common.annotations.GwtCompatible;
+import java.lang.annotation.Retention;
+import java.lang.annotation.Target;
+import javax.annotation.Nonnull;
+import javax.annotation.meta.TypeQualifierDefault;
+
+/**
+ * Marks all "top-level" types as non-null in a way that is recognized by Kotlin. Note that this
+ * unfortunately includes type-variable usages, so we also provide {@link ParametricNullness} to
+ * "undo" it as best we can.
+ */
+@GwtCompatible
+@Retention(RUNTIME)
+@Target(TYPE)
+@TypeQualifierDefault({FIELD, METHOD, PARAMETER})
+@Nonnull
+@interface ElementTypesAreNonnullByDefault {}
diff --git a/android/guava/src/com/google/common/primitives/Floats.java b/android/guava/src/com/google/common/primitives/Floats.java
index e379ebd30393..b038cb289636 100644
--- a/android/guava/src/com/google/common/primitives/Floats.java
+++ b/android/guava/src/com/google/common/primitives/Floats.java
@@ -34,7 +34,7 @@
 import java.util.Comparator;
 import java.util.List;
 import java.util.RandomAccess;
-import org.checkerframework.checker.nullness.compatqual.NullableDecl;
+import javax.annotation.CheckForNull;
 
 /**
  * Static utility methods pertaining to {@code float} primitives, that are not already found in
@@ -47,6 +47,7 @@
  * @since 1.0
  */
 @GwtCompatible(emulated = true)
+@ElementTypesAreNonnullByDefault
 public final class Floats extends FloatsMethodsForWeb {
   private Floats() {}
 
@@ -547,13 +548,13 @@ public Float get(int index) {
     }
 
     @Override
-    public boolean contains(Object target) {
+    public boolean contains(@CheckForNull Object target) {
       // Overridden to prevent a ton of boxing
       return (target instanceof Float) && Floats.indexOf(array, (Float) target, start, end) != -1;
     }
 
     @Override
-    public int indexOf(Object target) {
+    public int indexOf(@CheckForNull Object target) {
       // Overridden to prevent a ton of boxing
       if (target instanceof Float) {
         int i = Floats.indexOf(array, (Float) target, start, end);
@@ -565,7 +566,7 @@ public int indexOf(Object target) {
     }
 
     @Override
-    public int lastIndexOf(Object target) {
+    public int lastIndexOf(@CheckForNull Object target) {
       // Overridden to prevent a ton of boxing
       if (target instanceof Float) {
         int i = Floats.lastIndexOf(array, (Float) target, start, end);
@@ -596,7 +597,7 @@ public List<Float> subList(int fromIndex, int toIndex) {
     }
 
     @Override
-    public boolean equals(@NullableDecl Object object) {
+    public boolean equals(@CheckForNull Object object) {
       if (object == this) {
         return true;
       }
@@ -661,7 +662,7 @@ float[] toFloatArray() {
    */
   @Beta
   @GwtIncompatible // regular expressions
-  @NullableDecl
+  @CheckForNull
   public static Float tryParse(String string) {
     if (Doubles.FLOATING_POINT_PATTERN.matcher(string).matches()) {
       // TODO(lowasser): could be potentially optimized, but only with
diff --git a/android/guava/src/com/google/common/primitives/FloatsMethodsForWeb.java b/android/guava/src/com/google/common/primitives/FloatsMethodsForWeb.java
index acdb42f275b1..801e2f3ef110 100644
--- a/android/guava/src/com/google/common/primitives/FloatsMethodsForWeb.java
+++ b/android/guava/src/com/google/common/primitives/FloatsMethodsForWeb.java
@@ -21,4 +21,5 @@
  * version.
  */
 @GwtCompatible(emulated = true)
+@ElementTypesAreNonnullByDefault
 abstract class FloatsMethodsForWeb {}
diff --git a/android/guava/src/com/google/common/primitives/ImmutableDoubleArray.java b/android/guava/src/com/google/common/primitives/ImmutableDoubleArray.java
index 63efc45b5981..1627fab2baa8 100644
--- a/android/guava/src/com/google/common/primitives/ImmutableDoubleArray.java
+++ b/android/guava/src/com/google/common/primitives/ImmutableDoubleArray.java
@@ -28,7 +28,7 @@
 import java.util.Collection;
 import java.util.List;
 import java.util.RandomAccess;
-import org.checkerframework.checker.nullness.compatqual.NullableDecl;
+import javax.annotation.CheckForNull;
 
 /**
  * An immutable array of {@code double} values, with an API resembling {@link List}.
@@ -80,6 +80,7 @@
 @Beta
 @GwtCompatible
 @Immutable
+@ElementTypesAreNonnullByDefault
 public final class ImmutableDoubleArray implements Serializable {
   private static final ImmutableDoubleArray EMPTY = new ImmutableDoubleArray(new double[0]);
 
@@ -437,17 +438,17 @@ public Double get(int index) {
     }
 
     @Override
-    public boolean contains(Object target) {
+    public boolean contains(@CheckForNull Object target) {
       return indexOf(target) >= 0;
     }
 
     @Override
-    public int indexOf(Object target) {
+    public int indexOf(@CheckForNull Object target) {
       return target instanceof Double ? parent.indexOf((Double) target) : -1;
     }
 
     @Override
-    public int lastIndexOf(Object target) {
+    public int lastIndexOf(@CheckForNull Object target) {
       return target instanceof Double ? parent.lastIndexOf((Double) target) : -1;
     }
 
@@ -457,7 +458,7 @@ public List<Double> subList(int fromIndex, int toIndex) {
     }
 
     @Override
-    public boolean equals(@NullableDecl Object object) {
+    public boolean equals(@CheckForNull Object object) {
       if (object instanceof AsList) {
         AsList that = (AsList) object;
         return this.parent.equals(that.parent);
@@ -497,7 +498,7 @@ public String toString() {
    * values as this one, in the same order. Values are compared as if by {@link Double#equals}.
    */
   @Override
-  public boolean equals(@NullableDecl Object object) {
+  public boolean equals(@CheckForNull Object object) {
     if (object == this) {
       return true;
     }
diff --git a/android/guava/src/com/google/common/primitives/ImmutableIntArray.java b/android/guava/src/com/google/common/primitives/ImmutableIntArray.java
index 02d9b508a0e2..8f972c49b4fc 100644
--- a/android/guava/src/com/google/common/primitives/ImmutableIntArray.java
+++ b/android/guava/src/com/google/common/primitives/ImmutableIntArray.java
@@ -28,7 +28,7 @@
 import java.util.Collection;
 import java.util.List;
 import java.util.RandomAccess;
-import org.checkerframework.checker.nullness.compatqual.NullableDecl;
+import javax.annotation.CheckForNull;
 
 /**
  * An immutable array of {@code int} values, with an API resembling {@link List}.
@@ -80,6 +80,7 @@
 @Beta
 @GwtCompatible
 @Immutable
+@ElementTypesAreNonnullByDefault
 public final class ImmutableIntArray implements Serializable {
   private static final ImmutableIntArray EMPTY = new ImmutableIntArray(new int[0]);
 
@@ -432,17 +433,17 @@ public Integer get(int index) {
     }
 
     @Override
-    public boolean contains(Object target) {
+    public boolean contains(@CheckForNull Object target) {
       return indexOf(target) >= 0;
     }
 
     @Override
-    public int indexOf(Object target) {
+    public int indexOf(@CheckForNull Object target) {
       return target instanceof Integer ? parent.indexOf((Integer) target) : -1;
     }
 
     @Override
-    public int lastIndexOf(Object target) {
+    public int lastIndexOf(@CheckForNull Object target) {
       return target instanceof Integer ? parent.lastIndexOf((Integer) target) : -1;
     }
 
@@ -452,7 +453,7 @@ public List<Integer> subList(int fromIndex, int toIndex) {
     }
 
     @Override
-    public boolean equals(@NullableDecl Object object) {
+    public boolean equals(@CheckForNull Object object) {
       if (object instanceof AsList) {
         AsList that = (AsList) object;
         return this.parent.equals(that.parent);
@@ -492,7 +493,7 @@ public String toString() {
    * values as this one, in the same order.
    */
   @Override
-  public boolean equals(@NullableDecl Object object) {
+  public boolean equals(@CheckForNull Object object) {
     if (object == this) {
       return true;
     }
diff --git a/android/guava/src/com/google/common/primitives/ImmutableLongArray.java b/android/guava/src/com/google/common/primitives/ImmutableLongArray.java
index ce0e4b6dd80f..4ebf5b406fb9 100644
--- a/android/guava/src/com/google/common/primitives/ImmutableLongArray.java
+++ b/android/guava/src/com/google/common/primitives/ImmutableLongArray.java
@@ -28,7 +28,7 @@
 import java.util.Collection;
 import java.util.List;
 import java.util.RandomAccess;
-import org.checkerframework.checker.nullness.compatqual.NullableDecl;
+import javax.annotation.CheckForNull;
 
 /**
  * An immutable array of {@code long} values, with an API resembling {@link List}.
@@ -80,6 +80,7 @@
 @Beta
 @GwtCompatible
 @Immutable
+@ElementTypesAreNonnullByDefault
 public final class ImmutableLongArray implements Serializable {
   private static final ImmutableLongArray EMPTY = new ImmutableLongArray(new long[0]);
 
@@ -434,17 +435,17 @@ public Long get(int index) {
     }
 
     @Override
-    public boolean contains(Object target) {
+    public boolean contains(@CheckForNull Object target) {
       return indexOf(target) >= 0;
     }
 
     @Override
-    public int indexOf(Object target) {
+    public int indexOf(@CheckForNull Object target) {
       return target instanceof Long ? parent.indexOf((Long) target) : -1;
     }
 
     @Override
-    public int lastIndexOf(Object target) {
+    public int lastIndexOf(@CheckForNull Object target) {
       return target instanceof Long ? parent.lastIndexOf((Long) target) : -1;
     }
 
@@ -454,7 +455,7 @@ public List<Long> subList(int fromIndex, int toIndex) {
     }
 
     @Override
-    public boolean equals(@NullableDecl Object object) {
+    public boolean equals(@CheckForNull Object object) {
       if (object instanceof AsList) {
         AsList that = (AsList) object;
         return this.parent.equals(that.parent);
@@ -494,7 +495,7 @@ public String toString() {
    * values as this one, in the same order.
    */
   @Override
-  public boolean equals(@NullableDecl Object object) {
+  public boolean equals(@CheckForNull Object object) {
     if (object == this) {
       return true;
     }
diff --git a/android/guava/src/com/google/common/primitives/Ints.java b/android/guava/src/com/google/common/primitives/Ints.java
index 93b5ba0ac7b0..e07bdd88d93e 100644
--- a/android/guava/src/com/google/common/primitives/Ints.java
+++ b/android/guava/src/com/google/common/primitives/Ints.java
@@ -31,7 +31,7 @@
 import java.util.Comparator;
 import java.util.List;
 import java.util.RandomAccess;
-import org.checkerframework.checker.nullness.compatqual.NullableDecl;
+import javax.annotation.CheckForNull;
 
 /**
  * Static utility methods pertaining to {@code int} primitives, that are not already found in either
@@ -44,6 +44,7 @@
  * @since 1.0
  */
 @GwtCompatible(emulated = true)
+@ElementTypesAreNonnullByDefault
 public final class Ints extends IntsMethodsForWeb {
   private Ints() {}
 
@@ -593,13 +594,13 @@ public Integer get(int index) {
     }
 
     @Override
-    public boolean contains(Object target) {
+    public boolean contains(@CheckForNull Object target) {
       // Overridden to prevent a ton of boxing
       return (target instanceof Integer) && Ints.indexOf(array, (Integer) target, start, end) != -1;
     }
 
     @Override
-    public int indexOf(Object target) {
+    public int indexOf(@CheckForNull Object target) {
       // Overridden to prevent a ton of boxing
       if (target instanceof Integer) {
         int i = Ints.indexOf(array, (Integer) target, start, end);
@@ -611,7 +612,7 @@ public int indexOf(Object target) {
     }
 
     @Override
-    public int lastIndexOf(Object target) {
+    public int lastIndexOf(@CheckForNull Object target) {
       // Overridden to prevent a ton of boxing
       if (target instanceof Integer) {
         int i = Ints.lastIndexOf(array, (Integer) target, start, end);
@@ -642,7 +643,7 @@ public List<Integer> subList(int fromIndex, int toIndex) {
     }
 
     @Override
-    public boolean equals(@NullableDecl Object object) {
+    public boolean equals(@CheckForNull Object object) {
       if (object == this) {
         return true;
       }
@@ -706,7 +707,7 @@ int[] toIntArray() {
    * @since 11.0
    */
   @Beta
-  @NullableDecl
+  @CheckForNull
   public static Integer tryParse(String string) {
     return tryParse(string, 10);
   }
@@ -732,7 +733,7 @@ public static Integer tryParse(String string) {
    * @since 19.0
    */
   @Beta
-  @NullableDecl
+  @CheckForNull
   public static Integer tryParse(String string, int radix) {
     Long result = Longs.tryParse(string, radix);
     if (result == null || result.longValue() != result.intValue()) {
diff --git a/android/guava/src/com/google/common/primitives/IntsMethodsForWeb.java b/android/guava/src/com/google/common/primitives/IntsMethodsForWeb.java
index cb87bd2929f8..c59c6b05862d 100644
--- a/android/guava/src/com/google/common/primitives/IntsMethodsForWeb.java
+++ b/android/guava/src/com/google/common/primitives/IntsMethodsForWeb.java
@@ -21,4 +21,5 @@
  * version.
  */
 @GwtCompatible(emulated = true)
+@ElementTypesAreNonnullByDefault
 abstract class IntsMethodsForWeb {}
diff --git a/android/guava/src/com/google/common/primitives/Longs.java b/android/guava/src/com/google/common/primitives/Longs.java
index 81838ce61cdc..6f60656bcb1a 100644
--- a/android/guava/src/com/google/common/primitives/Longs.java
+++ b/android/guava/src/com/google/common/primitives/Longs.java
@@ -30,7 +30,7 @@
 import java.util.Comparator;
 import java.util.List;
 import java.util.RandomAccess;
-import org.checkerframework.checker.nullness.compatqual.NullableDecl;
+import javax.annotation.CheckForNull;
 
 /**
  * Static utility methods pertaining to {@code long} primitives, that are not already found in
@@ -43,6 +43,7 @@
  * @since 1.0
  */
 @GwtCompatible
+@ElementTypesAreNonnullByDefault
 public final class Longs {
   private Longs() {}
 
@@ -361,7 +362,7 @@ static int digit(char c) {
    * @since 14.0
    */
   @Beta
-  @NullableDecl
+  @CheckForNull
   public static Long tryParse(String string) {
     return tryParse(string, 10);
   }
@@ -387,7 +388,7 @@ public static Long tryParse(String string) {
    * @since 19.0
    */
   @Beta
-  @NullableDecl
+  @CheckForNull
   public static Long tryParse(String string, int radix) {
     if (checkNotNull(string).isEmpty()) {
       return null;
@@ -689,13 +690,13 @@ public Long get(int index) {
     }
 
     @Override
-    public boolean contains(Object target) {
+    public boolean contains(@CheckForNull Object target) {
       // Overridden to prevent a ton of boxing
       return (target instanceof Long) && Longs.indexOf(array, (Long) target, start, end) != -1;
     }
 
     @Override
-    public int indexOf(Object target) {
+    public int indexOf(@CheckForNull Object target) {
       // Overridden to prevent a ton of boxing
       if (target instanceof Long) {
         int i = Longs.indexOf(array, (Long) target, start, end);
@@ -707,7 +708,7 @@ public int indexOf(Object target) {
     }
 
     @Override
-    public int lastIndexOf(Object target) {
+    public int lastIndexOf(@CheckForNull Object target) {
       // Overridden to prevent a ton of boxing
       if (target instanceof Long) {
         int i = Longs.lastIndexOf(array, (Long) target, start, end);
@@ -738,7 +739,7 @@ public List<Long> subList(int fromIndex, int toIndex) {
     }
 
     @Override
-    public boolean equals(@NullableDecl Object object) {
+    public boolean equals(@CheckForNull Object object) {
       if (object == this) {
         return true;
       }
diff --git a/android/guava/src/com/google/common/primitives/ParametricNullness.java b/android/guava/src/com/google/common/primitives/ParametricNullness.java
new file mode 100644
index 000000000000..4289b9b164f1
--- /dev/null
+++ b/android/guava/src/com/google/common/primitives/ParametricNullness.java
@@ -0,0 +1,52 @@
+/*
+ * Copyright (C) 2021 The Guava Authors
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package com.google.common.primitives;
+
+import static java.lang.annotation.ElementType.FIELD;
+import static java.lang.annotation.ElementType.METHOD;
+import static java.lang.annotation.ElementType.PARAMETER;
+import static java.lang.annotation.RetentionPolicy.RUNTIME;
+
+import com.google.common.annotations.GwtCompatible;
+import java.lang.annotation.Retention;
+import java.lang.annotation.Target;
+
+/**
+ * Marks a "top-level" type-variable usage as the closest we can get to "non-nullable when
+ * non-nullable; nullable when nullable" (like the Android <a
+ * href="https://android.googlesource.com/platform/libcore/+/master/luni/src/main/java/libcore/util/NullFromTypeParam.java">{@code
+ * NullFromTypeParam}</a>).
+ *
+ * <p>Consumers of this annotation include:
+ *
+ * <ul>
+ *   <li>Kotlin, for which it makes the type-variable usage (a) a Kotlin platform type when the type
+ *       argument is non-nullable and (b) nullable when the type argument is nullable. We use this
+ *       to "undo" {@link ElementTypesAreNonnullByDefault}.
+ *   <li><a href="https://developers.google.com/j2objc">J2ObjC</a>
+ *   <li>{@code NullPointerTester}, at least in the Android backport (where the type-use annotations
+ *       {@code NullPointerTester} would need are not available) and in case of <a
+ *       href="https://bugs.openjdk.java.net/browse/JDK-8202469">JDK-8202469</a>
+ * </ul>
+ *
+ */
+@GwtCompatible
+@Retention(RUNTIME)
+@Target({FIELD, METHOD, PARAMETER})
+@javax.annotation.meta.TypeQualifierNickname
+@javax.annotation.Nonnull(when = javax.annotation.meta.When.UNKNOWN)
+@interface ParametricNullness {}
diff --git a/android/guava/src/com/google/common/primitives/ParseRequest.java b/android/guava/src/com/google/common/primitives/ParseRequest.java
index 97b0f1b57abc..a102d69b06e1 100644
--- a/android/guava/src/com/google/common/primitives/ParseRequest.java
+++ b/android/guava/src/com/google/common/primitives/ParseRequest.java
@@ -18,6 +18,7 @@
 
 /** A string to be parsed as a number and the radix to interpret it in. */
 @GwtCompatible
+@ElementTypesAreNonnullByDefault
 final class ParseRequest {
   final String rawValue;
   final int radix;
diff --git a/android/guava/src/com/google/common/primitives/Platform.java b/android/guava/src/com/google/common/primitives/Platform.java
index 82b902b9ccba..83b248517993 100644
--- a/android/guava/src/com/google/common/primitives/Platform.java
+++ b/android/guava/src/com/google/common/primitives/Platform.java
@@ -18,6 +18,7 @@
 
 /** Methods factored out so that they can be emulated differently in GWT. */
 @GwtCompatible(emulated = true)
+@ElementTypesAreNonnullByDefault
 final class Platform {
   static void checkGwtRpcEnabled() {}
 
diff --git a/android/guava/src/com/google/common/primitives/Primitives.java b/android/guava/src/com/google/common/primitives/Primitives.java
index 1bdc7400f330..7ceed036555a 100644
--- a/android/guava/src/com/google/common/primitives/Primitives.java
+++ b/android/guava/src/com/google/common/primitives/Primitives.java
@@ -30,6 +30,7 @@
  * @since 1.0
  */
 @GwtIncompatible
+@ElementTypesAreNonnullByDefault
 public final class Primitives {
   private Primitives() {}
 
diff --git a/android/guava/src/com/google/common/primitives/Shorts.java b/android/guava/src/com/google/common/primitives/Shorts.java
index dc58138814b8..09e0f7cfc312 100644
--- a/android/guava/src/com/google/common/primitives/Shorts.java
+++ b/android/guava/src/com/google/common/primitives/Shorts.java
@@ -31,7 +31,7 @@
 import java.util.Comparator;
 import java.util.List;
 import java.util.RandomAccess;
-import org.checkerframework.checker.nullness.compatqual.NullableDecl;
+import javax.annotation.CheckForNull;
 
 /**
  * Static utility methods pertaining to {@code short} primitives, that are not already found in
@@ -44,6 +44,7 @@
  * @since 1.0
  */
 @GwtCompatible(emulated = true)
+@ElementTypesAreNonnullByDefault
 public final class Shorts extends ShortsMethodsForWeb {
   private Shorts() {}
 
@@ -592,13 +593,13 @@ public Short get(int index) {
     }
 
     @Override
-    public boolean contains(@NullableDecl Object target) {
+    public boolean contains(@CheckForNull Object target) {
       // Overridden to prevent a ton of boxing
       return (target instanceof Short) && Shorts.indexOf(array, (Short) target, start, end) != -1;
     }
 
     @Override
-    public int indexOf(@NullableDecl Object target) {
+    public int indexOf(@CheckForNull Object target) {
       // Overridden to prevent a ton of boxing
       if (target instanceof Short) {
         int i = Shorts.indexOf(array, (Short) target, start, end);
@@ -610,7 +611,7 @@ public int indexOf(@NullableDecl Object target) {
     }
 
     @Override
-    public int lastIndexOf(@NullableDecl Object target) {
+    public int lastIndexOf(@CheckForNull Object target) {
       // Overridden to prevent a ton of boxing
       if (target instanceof Short) {
         int i = Shorts.lastIndexOf(array, (Short) target, start, end);
@@ -641,7 +642,7 @@ public List<Short> subList(int fromIndex, int toIndex) {
     }
 
     @Override
-    public boolean equals(@NullableDecl Object object) {
+    public boolean equals(@CheckForNull Object object) {
       if (object == this) {
         return true;
       }
diff --git a/android/guava/src/com/google/common/primitives/ShortsMethodsForWeb.java b/android/guava/src/com/google/common/primitives/ShortsMethodsForWeb.java
index c36276838cc6..bb0ff103ce2f 100644
--- a/android/guava/src/com/google/common/primitives/ShortsMethodsForWeb.java
+++ b/android/guava/src/com/google/common/primitives/ShortsMethodsForWeb.java
@@ -21,4 +21,5 @@
  * version.
  */
 @GwtCompatible(emulated = true)
+@ElementTypesAreNonnullByDefault
 abstract class ShortsMethodsForWeb {}
diff --git a/android/guava/src/com/google/common/primitives/SignedBytes.java b/android/guava/src/com/google/common/primitives/SignedBytes.java
index e475c41fe049..5fabaab6bd93 100644
--- a/android/guava/src/com/google/common/primitives/SignedBytes.java
+++ b/android/guava/src/com/google/common/primitives/SignedBytes.java
@@ -36,6 +36,7 @@
 // TODO(kevinb): how to prevent warning on UnsignedBytes when building GWT
 // javadoc?
 @GwtCompatible
+@ElementTypesAreNonnullByDefault
 public final class SignedBytes {
   private SignedBytes() {}
 
diff --git a/android/guava/src/com/google/common/primitives/UnsignedBytes.java b/android/guava/src/com/google/common/primitives/UnsignedBytes.java
index 4275f8a6ecc5..db4f489e491f 100644
--- a/android/guava/src/com/google/common/primitives/UnsignedBytes.java
+++ b/android/guava/src/com/google/common/primitives/UnsignedBytes.java
@@ -17,6 +17,7 @@
 import static com.google.common.base.Preconditions.checkArgument;
 import static com.google.common.base.Preconditions.checkNotNull;
 import static com.google.common.base.Preconditions.checkPositionIndexes;
+import static java.util.Objects.requireNonNull;
 
 import com.google.common.annotations.Beta;
 import com.google.common.annotations.GwtIncompatible;
@@ -43,6 +44,7 @@
  * @since 1.0
  */
 @GwtIncompatible
+@ElementTypesAreNonnullByDefault
 public final class UnsignedBytes {
   private UnsignedBytes() {}
 
@@ -363,7 +365,7 @@ public sun.misc.Unsafe run() throws Exception {
 
       @Override
       public int compare(byte[] left, byte[] right) {
-        final int stride = 8;
+        int stride = 8;
         int minLength = Math.min(left.length, right.length);
         int strideLimit = minLength & ~(stride - 1);
         int i;
@@ -437,9 +439,12 @@ static Comparator<byte[]> getBestComparator() {
       try {
         Class<?> theClass = Class.forName(UNSAFE_COMPARATOR_NAME);
 
+        // requireNonNull is safe because the class is an enum.
+        Object[] constants = requireNonNull(theClass.getEnumConstants());
+
         // yes, UnsafeComparator does implement Comparator<byte[]>
         @SuppressWarnings("unchecked")
-        Comparator<byte[]> comparator = (Comparator<byte[]>) theClass.getEnumConstants()[0];
+        Comparator<byte[]> comparator = (Comparator<byte[]>) constants[0];
         return comparator;
       } catch (Throwable t) { // ensure we really catch *everything*
         return lexicographicalComparatorJavaImpl();
diff --git a/android/guava/src/com/google/common/primitives/UnsignedInteger.java b/android/guava/src/com/google/common/primitives/UnsignedInteger.java
index 74740e9b92cf..0b30cef3f4c6 100644
--- a/android/guava/src/com/google/common/primitives/UnsignedInteger.java
+++ b/android/guava/src/com/google/common/primitives/UnsignedInteger.java
@@ -23,7 +23,7 @@
 import com.google.common.annotations.GwtCompatible;
 import com.google.common.annotations.GwtIncompatible;
 import java.math.BigInteger;
-import org.checkerframework.checker.nullness.compatqual.NullableDecl;
+import javax.annotation.CheckForNull;
 
 /**
  * A wrapper class for unsigned {@code int} values, supporting arithmetic operations.
@@ -39,6 +39,7 @@
  * @since 11.0
  */
 @GwtCompatible(emulated = true)
+@ElementTypesAreNonnullByDefault
 public final class UnsignedInteger extends Number implements Comparable<UnsignedInteger> {
   public static final UnsignedInteger ZERO = fromIntBits(0);
   public static final UnsignedInteger ONE = fromIntBits(1);
@@ -226,7 +227,7 @@ public int hashCode() {
   }
 
   @Override
-  public boolean equals(@NullableDecl Object obj) {
+  public boolean equals(@CheckForNull Object obj) {
     if (obj instanceof UnsignedInteger) {
       UnsignedInteger other = (UnsignedInteger) obj;
       return value == other.value;
diff --git a/android/guava/src/com/google/common/primitives/UnsignedInts.java b/android/guava/src/com/google/common/primitives/UnsignedInts.java
index 9eda96928fa5..ec6474e20f8a 100644
--- a/android/guava/src/com/google/common/primitives/UnsignedInts.java
+++ b/android/guava/src/com/google/common/primitives/UnsignedInts.java
@@ -47,6 +47,7 @@
  */
 @Beta
 @GwtCompatible
+@ElementTypesAreNonnullByDefault
 public final class UnsignedInts {
   static final long INT_MASK = 0xffffffffL;
 
diff --git a/android/guava/src/com/google/common/primitives/UnsignedLong.java b/android/guava/src/com/google/common/primitives/UnsignedLong.java
index 448579071d25..d803634f4946 100644
--- a/android/guava/src/com/google/common/primitives/UnsignedLong.java
+++ b/android/guava/src/com/google/common/primitives/UnsignedLong.java
@@ -21,7 +21,7 @@
 import com.google.errorprone.annotations.CanIgnoreReturnValue;
 import java.io.Serializable;
 import java.math.BigInteger;
-import org.checkerframework.checker.nullness.compatqual.NullableDecl;
+import javax.annotation.CheckForNull;
 
 /**
  * A wrapper class for unsigned {@code long} values, supporting arithmetic operations.
@@ -38,6 +38,7 @@
  * @since 11.0
  */
 @GwtCompatible(serializable = true)
+@ElementTypesAreNonnullByDefault
 public final class UnsignedLong extends Number implements Comparable<UnsignedLong>, Serializable {
 
   private static final long UNSIGNED_MASK = 0x7fffffffffffffffL;
@@ -195,12 +196,12 @@ public long longValue() {
    */
   @Override
   public float floatValue() {
-    @SuppressWarnings("cast")
-    float fValue = (float) (value & UNSIGNED_MASK);
-    if (value < 0) {
-      fValue += 0x1.0p63f;
+    if (value >= 0) {
+      return (float) value;
     }
-    return fValue;
+    // The top bit is set, which means that the float value is going to come from the top 24 bits.
+    // So we can ignore the bottom 8, except for rounding. See doubleValue() for more.
+    return (float) ((value >>> 1) | (value & 1)) * 2f;
   }
 
   /**
@@ -209,12 +210,15 @@ public float floatValue() {
    */
   @Override
   public double doubleValue() {
-    @SuppressWarnings("cast")
-    double dValue = (double) (value & UNSIGNED_MASK);
-    if (value < 0) {
-      dValue += 0x1.0p63;
+    if (value >= 0) {
+      return (double) value;
     }
-    return dValue;
+    // The top bit is set, which means that the double value is going to come from the top 53 bits.
+    // So we can ignore the bottom 11, except for rounding. We can unsigned-shift right 1, aka
+    // unsigned-divide by 2, and convert that. Then we'll get exactly half of the desired double
+    // value. But in the specific case where the bottom two bits of the original number are 01, we
+    // want to replace that with 1 in the shifted value for correct rounding.
+    return (double) ((value >>> 1) | (value & 1)) * 2.0;
   }
 
   /** Returns the value of this {@code UnsignedLong} as a {@link BigInteger}. */
@@ -238,7 +242,7 @@ public int hashCode() {
   }
 
   @Override
-  public boolean equals(@NullableDecl Object obj) {
+  public boolean equals(@CheckForNull Object obj) {
     if (obj instanceof UnsignedLong) {
       UnsignedLong other = (UnsignedLong) obj;
       return value == other.value;
diff --git a/android/guava/src/com/google/common/primitives/UnsignedLongs.java b/android/guava/src/com/google/common/primitives/UnsignedLongs.java
index a1fccc2b968f..31c51cc3464d 100644
--- a/android/guava/src/com/google/common/primitives/UnsignedLongs.java
+++ b/android/guava/src/com/google/common/primitives/UnsignedLongs.java
@@ -50,6 +50,7 @@
  */
 @Beta
 @GwtCompatible
+@ElementTypesAreNonnullByDefault
 public final class UnsignedLongs {
   private UnsignedLongs() {}
 
diff --git a/android/guava/src/com/google/common/reflect/AbstractInvocationHandler.java b/android/guava/src/com/google/common/reflect/AbstractInvocationHandler.java
index 67655da9c1d3..ff921959db39 100644
--- a/android/guava/src/com/google/common/reflect/AbstractInvocationHandler.java
+++ b/android/guava/src/com/google/common/reflect/AbstractInvocationHandler.java
@@ -14,12 +14,12 @@
 
 package com.google.common.reflect;
 
-import com.google.common.annotations.Beta;
 import java.lang.reflect.InvocationHandler;
 import java.lang.reflect.Method;
 import java.lang.reflect.Proxy;
 import java.util.Arrays;
-import org.checkerframework.checker.nullness.compatqual.NullableDecl;
+import javax.annotation.CheckForNull;
+import org.checkerframework.checker.nullness.qual.Nullable;
 
 /**
  * Abstract implementation of {@link InvocationHandler} that handles {@link Object#equals}, {@link
@@ -38,7 +38,7 @@
  * @author Ben Yu
  * @since 12.0
  */
-@Beta
+@ElementTypesAreNonnullByDefault
 public abstract class AbstractInvocationHandler implements InvocationHandler {
 
   private static final Object[] NO_ARGS = {};
@@ -59,7 +59,8 @@ public abstract class AbstractInvocationHandler implements InvocationHandler {
    * </ul>
    */
   @Override
-  public final Object invoke(Object proxy, Method method, @NullableDecl Object[] args)
+  @CheckForNull
+  public final Object invoke(Object proxy, Method method, @CheckForNull @Nullable Object[] args)
       throws Throwable {
     if (args == null) {
       args = NO_ARGS;
@@ -94,7 +95,8 @@ public final Object invoke(Object proxy, Method method, @NullableDecl Object[] a
    * <p>Unlike {@link #invoke}, {@code args} will never be null. When the method has no parameter,
    * an empty array is passed in.
    */
-  protected abstract Object handleInvocation(Object proxy, Method method, Object[] args)
+  @CheckForNull
+  protected abstract Object handleInvocation(Object proxy, Method method, @Nullable Object[] args)
       throws Throwable;
 
   /**
@@ -109,7 +111,7 @@ protected abstract Object handleInvocation(Object proxy, Method method, Object[]
    * <p>Subclasses can override this method to provide custom equality.
    */
   @Override
-  public boolean equals(Object obj) {
+  public boolean equals(@CheckForNull Object obj) {
     return super.equals(obj);
   }
 
diff --git a/android/guava/src/com/google/common/reflect/ClassPath.java b/android/guava/src/com/google/common/reflect/ClassPath.java
index 206d5b8af475..d15bb5055d33 100644
--- a/android/guava/src/com/google/common/reflect/ClassPath.java
+++ b/android/guava/src/com/google/common/reflect/ClassPath.java
@@ -20,10 +20,8 @@
 import static com.google.common.base.StandardSystemProperty.PATH_SEPARATOR;
 import static java.util.logging.Level.WARNING;
 
-import com.google.common.annotations.Beta;
 import com.google.common.annotations.VisibleForTesting;
 import com.google.common.base.CharMatcher;
-import com.google.common.base.Predicate;
 import com.google.common.base.Splitter;
 import com.google.common.collect.FluentIterable;
 import com.google.common.collect.ImmutableList;
@@ -51,19 +49,40 @@
 import java.util.jar.JarFile;
 import java.util.jar.Manifest;
 import java.util.logging.Logger;
-import org.checkerframework.checker.nullness.compatqual.NullableDecl;
+import javax.annotation.CheckForNull;
 
 /**
  * Scans the source of a {@link ClassLoader} and finds all loadable classes and resources.
  *
- * <p><b>Warning:</b> Current limitations:
+ * <h2>Prefer <a href="https://github.com/classgraph/classgraph/wiki">ClassGraph</a> over {@code
+ * ClassPath}</h2>
+ *
+ * <p>We recommend using <a href="https://github.com/classgraph/classgraph/wiki">ClassGraph</a>
+ * instead of {@code ClassPath}. ClassGraph improves upon {@code ClassPath} in several ways,
+ * including addressing many of its limitations. Limitations of {@code ClassPath} include:
  *
  * <ul>
- *   <li>Looks only for files and JARs in URLs available from {@link URLClassLoader} instances or
- *       the {@linkplain ClassLoader#getSystemClassLoader() system class loader}.
- *   <li>Only understands {@code file:} URLs.
+ *   <li>It looks only for files and JARs in URLs available from {@link URLClassLoader} instances or
+ *       the {@linkplain ClassLoader#getSystemClassLoader() system class loader}. This means it does
+ *       not look for classes in the <i>module path</i>.
+ *   <li>It understands only {@code file:} URLs. This means that it does not understand <a
+ *       href="https://openjdk.java.net/jeps/220">{@code jrt:/} URLs</a>, among <a
+ *       href="https://github.com/classgraph/classgraph/wiki/Classpath-specification-mechanisms">others</a>.
+ *   <li>It does not know how to look for classes when running under an Android VM. (ClassGraph does
+ *       not support this directly, either, but ClassGraph documents how to <a
+ *       href="https://github.com/classgraph/classgraph/wiki/Build-Time-Scanning">perform build-time
+ *       classpath scanning and make the results available to an Android app</a>.)
+ *   <li>Like all of Guava, it is not tested under Windows. We have gotten <a
+ *       href="https://github.com/google/guava/issues/2130">a report of a specific bug under
+ *       Windows</a>.
+ *   <li>It <a href="https://github.com/google/guava/issues/2712">returns only one resource for a
+ *       given path</a>, even if resources with that path appear in multiple jars or directories.
+ *   <li>It assumes that <a href="https://github.com/google/guava/issues/3349">any class with a
+ *       {@code $} in its name is a nested class</a>.
  * </ul>
  *
+ * <h2>{@code ClassPath} and symlinks</h2>
+ *
  * <p>In the case of directory classloaders, symlinks are supported but cycles are not traversed.
  * This guarantees discovery of each <em>unique</em> loadable resource. However, not all possible
  * aliases for resources on cyclic paths will be listed.
@@ -71,7 +90,7 @@
  * @author Ben Yu
  * @since 14.0
  */
-@Beta
+@ElementTypesAreNonnullByDefault
 public final class ClassPath {
   private static final Logger logger = Logger.getLogger(ClassPath.class.getName());
 
@@ -145,13 +164,7 @@ public ImmutableSet<ClassInfo> getAllClasses() {
   public ImmutableSet<ClassInfo> getTopLevelClasses() {
     return FluentIterable.from(resources)
         .filter(ClassInfo.class)
-        .filter(
-            new Predicate<ClassInfo>() {
-              @Override
-              public boolean apply(ClassInfo info) {
-                return info.isTopLevel();
-              }
-            })
+        .filter(ClassInfo::isTopLevel)
         .toSet();
   }
 
@@ -189,7 +202,6 @@ public ImmutableSet<ClassInfo> getTopLevelClassesRecursive(String packageName) {
    *
    * @since 14.0
    */
-  @Beta
   public static class ResourceInfo {
     private final File file;
     private final String resourceName;
@@ -265,7 +277,7 @@ public int hashCode() {
     }
 
     @Override
-    public boolean equals(Object obj) {
+    public boolean equals(@CheckForNull Object obj) {
       if (obj instanceof ResourceInfo) {
         ResourceInfo that = (ResourceInfo) obj;
         return resourceName.equals(that.resourceName) && loader == that.loader;
@@ -285,7 +297,6 @@ public String toString() {
    *
    * @since 14.0
    */
-  @Beta
   public static final class ClassInfo extends ResourceInfo {
     private final String className;
 
@@ -297,8 +308,13 @@ public static final class ClassInfo extends ResourceInfo {
     /**
      * Returns the package name of the class, without attempting to load the class.
      *
-     * <p>Behaves identically to {@link Package#getName()} but does not require the class (or
-     * package) to be loaded.
+     * <p>Behaves similarly to {@code class.getPackage().}{@link Package#getName() getName()} but
+     * does not require the class (or package) to be loaded.
+     *
+     * <p>But note that this method may behave differently for a class in the default package: For
+     * such classes, this method always returns an empty string. But under some version of Java,
+     * {@code class.getPackage().getName()} produces a {@code NullPointerException} because {@code
+     * class.getPackage()} returns {@code null}.
      */
     public String getPackageName() {
       return Reflection.getPackageName(className);
@@ -307,8 +323,11 @@ public String getPackageName() {
     /**
      * Returns the simple name of the underlying class as given in the source code.
      *
-     * <p>Behaves identically to {@link Class#getSimpleName()} but does not require the class to be
+     * <p>Behaves similarly to {@link Class#getSimpleName()} but does not require the class to be
      * loaded.
+     *
+     * <p>But note that this class uses heuristics to identify the simple name. See a related
+     * discussion in <a href="https://github.com/google/guava/issues/3349">issue 3349</a>.
      */
     public String getSimpleName() {
       int lastDollarSign = className.lastIndexOf('$');
@@ -531,7 +550,7 @@ private void scanDirectory(
     }
 
     @Override
-    public boolean equals(Object obj) {
+    public boolean equals(@CheckForNull Object obj) {
       if (obj instanceof LocationInfo) {
         LocationInfo that = (LocationInfo) obj;
         return home.equals(that.home) && classloader.equals(that.classloader);
@@ -559,7 +578,7 @@ public String toString() {
    */
   @VisibleForTesting
   static ImmutableSet<File> getClassPathFromManifest(
-      File jarFile, @NullableDecl Manifest manifest) {
+      File jarFile, @CheckForNull Manifest manifest) {
     if (manifest == null) {
       return ImmutableSet.of();
     }
diff --git a/android/guava/src/com/google/common/reflect/Element.java b/android/guava/src/com/google/common/reflect/Element.java
deleted file mode 100644
index e2b9652353be..000000000000
--- a/android/guava/src/com/google/common/reflect/Element.java
+++ /dev/null
@@ -1,178 +0,0 @@
-/*
- * Copyright (C) 2012 The Guava Authors
- *
- * Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file except
- * in compliance with the License. You may obtain a copy of the License at
- *
- * http://www.apache.org/licenses/LICENSE-2.0
- *
- * Unless required by applicable law or agreed to in writing, software distributed under the License
- * is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express
- * or implied. See the License for the specific language governing permissions and limitations under
- * the License.
- */
-
-package com.google.common.reflect;
-
-import static com.google.common.base.Preconditions.checkNotNull;
-
-import java.lang.annotation.Annotation;
-import java.lang.reflect.AccessibleObject;
-import java.lang.reflect.Constructor;
-import java.lang.reflect.Field;
-import java.lang.reflect.Member;
-import java.lang.reflect.Method;
-import java.lang.reflect.Modifier;
-import org.checkerframework.checker.nullness.compatqual.NullableDecl;
-
-/**
- * Represents either a {@link Field}, a {@link Method} or a {@link Constructor}. Provides
- * convenience methods such as {@link #isPublic} and {@link #isPackagePrivate}.
- *
- * @author Ben Yu
- */
-class Element extends AccessibleObject implements Member {
-
-  private final AccessibleObject accessibleObject;
-  private final Member member;
-
-  <M extends AccessibleObject & Member> Element(M member) {
-    checkNotNull(member);
-    this.accessibleObject = member;
-    this.member = member;
-  }
-
-  public TypeToken<?> getOwnerType() {
-    return TypeToken.of(getDeclaringClass());
-  }
-
-  @Override
-  public final boolean isAnnotationPresent(Class<? extends Annotation> annotationClass) {
-    return accessibleObject.isAnnotationPresent(annotationClass);
-  }
-
-  @Override
-  public final <A extends Annotation> A getAnnotation(Class<A> annotationClass) {
-    return accessibleObject.getAnnotation(annotationClass);
-  }
-
-  @Override
-  public final Annotation[] getAnnotations() {
-    return accessibleObject.getAnnotations();
-  }
-
-  @Override
-  public final Annotation[] getDeclaredAnnotations() {
-    return accessibleObject.getDeclaredAnnotations();
-  }
-
-  @Override
-  public final void setAccessible(boolean flag) throws SecurityException {
-    accessibleObject.setAccessible(flag);
-  }
-
-  @Override
-  public final boolean isAccessible() {
-    return accessibleObject.isAccessible();
-  }
-
-  @Override
-  public Class<?> getDeclaringClass() {
-    return member.getDeclaringClass();
-  }
-
-  @Override
-  public final String getName() {
-    return member.getName();
-  }
-
-  @Override
-  public final int getModifiers() {
-    return member.getModifiers();
-  }
-
-  @Override
-  public final boolean isSynthetic() {
-    return member.isSynthetic();
-  }
-
-  /** Returns true if the element is public. */
-  public final boolean isPublic() {
-    return Modifier.isPublic(getModifiers());
-  }
-
-  /** Returns true if the element is protected. */
-  public final boolean isProtected() {
-    return Modifier.isProtected(getModifiers());
-  }
-
-  /** Returns true if the element is package-private. */
-  public final boolean isPackagePrivate() {
-    return !isPrivate() && !isPublic() && !isProtected();
-  }
-
-  /** Returns true if the element is private. */
-  public final boolean isPrivate() {
-    return Modifier.isPrivate(getModifiers());
-  }
-
-  /** Returns true if the element is static. */
-  public final boolean isStatic() {
-    return Modifier.isStatic(getModifiers());
-  }
-
-  /**
-   * Returns {@code true} if this method is final, per {@code Modifier.isFinal(getModifiers())}.
-   *
-   * <p>Note that a method may still be effectively "final", or non-overridable when it has no
-   * {@code final} keyword. For example, it could be private, or it could be declared by a final
-   * class. To tell whether a method is overridable, use {@link Invokable#isOverridable}.
-   */
-  public final boolean isFinal() {
-    return Modifier.isFinal(getModifiers());
-  }
-
-  /** Returns true if the method is abstract. */
-  public final boolean isAbstract() {
-    return Modifier.isAbstract(getModifiers());
-  }
-
-  /** Returns true if the element is native. */
-  public final boolean isNative() {
-    return Modifier.isNative(getModifiers());
-  }
-
-  /** Returns true if the method is synchronized. */
-  public final boolean isSynchronized() {
-    return Modifier.isSynchronized(getModifiers());
-  }
-
-  /** Returns true if the field is volatile. */
-  final boolean isVolatile() {
-    return Modifier.isVolatile(getModifiers());
-  }
-
-  /** Returns true if the field is transient. */
-  final boolean isTransient() {
-    return Modifier.isTransient(getModifiers());
-  }
-
-  @Override
-  public boolean equals(@NullableDecl Object obj) {
-    if (obj instanceof Element) {
-      Element that = (Element) obj;
-      return getOwnerType().equals(that.getOwnerType()) && member.equals(that.member);
-    }
-    return false;
-  }
-
-  @Override
-  public int hashCode() {
-    return member.hashCode();
-  }
-
-  @Override
-  public String toString() {
-    return member.toString();
-  }
-}
diff --git a/android/guava/src/com/google/common/reflect/ElementTypesAreNonnullByDefault.java b/android/guava/src/com/google/common/reflect/ElementTypesAreNonnullByDefault.java
new file mode 100644
index 000000000000..0e8ef3cb7bcb
--- /dev/null
+++ b/android/guava/src/com/google/common/reflect/ElementTypesAreNonnullByDefault.java
@@ -0,0 +1,41 @@
+/*
+ * Copyright (C) 2021 The Guava Authors
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package com.google.common.reflect;
+
+import static java.lang.annotation.ElementType.FIELD;
+import static java.lang.annotation.ElementType.METHOD;
+import static java.lang.annotation.ElementType.PARAMETER;
+import static java.lang.annotation.ElementType.TYPE;
+import static java.lang.annotation.RetentionPolicy.RUNTIME;
+
+import com.google.common.annotations.GwtCompatible;
+import java.lang.annotation.Retention;
+import java.lang.annotation.Target;
+import javax.annotation.Nonnull;
+import javax.annotation.meta.TypeQualifierDefault;
+
+/**
+ * Marks all "top-level" types as non-null in a way that is recognized by Kotlin. Note that this
+ * unfortunately includes type-variable usages, so we also provide {@link ParametricNullness} to
+ * "undo" it as best we can.
+ */
+@GwtCompatible
+@Retention(RUNTIME)
+@Target(TYPE)
+@TypeQualifierDefault({FIELD, METHOD, PARAMETER})
+@Nonnull
+@interface ElementTypesAreNonnullByDefault {}
diff --git a/android/guava/src/com/google/common/reflect/ImmutableTypeToInstanceMap.java b/android/guava/src/com/google/common/reflect/ImmutableTypeToInstanceMap.java
index 7fad5ded3bdf..6273704a1072 100644
--- a/android/guava/src/com/google/common/reflect/ImmutableTypeToInstanceMap.java
+++ b/android/guava/src/com/google/common/reflect/ImmutableTypeToInstanceMap.java
@@ -14,12 +14,12 @@
 
 package com.google.common.reflect;
 
-import com.google.common.annotations.Beta;
 import com.google.common.collect.ForwardingMap;
 import com.google.common.collect.ImmutableMap;
 import com.google.errorprone.annotations.CanIgnoreReturnValue;
 import com.google.errorprone.annotations.DoNotCall;
 import java.util.Map;
+import javax.annotation.CheckForNull;
 
 /**
  * A type-to-instance map backed by an {@link ImmutableMap}. See also {@link
@@ -28,18 +28,18 @@
  * @author Ben Yu
  * @since 13.0
  */
-@Beta
+@ElementTypesAreNonnullByDefault
 public final class ImmutableTypeToInstanceMap<B> extends ForwardingMap<TypeToken<? extends B>, B>
     implements TypeToInstanceMap<B> {
 
   /** Returns an empty type to instance map. */
   public static <B> ImmutableTypeToInstanceMap<B> of() {
-    return new ImmutableTypeToInstanceMap<B>(ImmutableMap.<TypeToken<? extends B>, B>of());
+    return new ImmutableTypeToInstanceMap<>(ImmutableMap.<TypeToken<? extends B>, B>of());
   }
 
   /** Returns a new builder. */
   public static <B> Builder<B> builder() {
-    return new Builder<B>();
+    return new Builder<>();
   }
 
   /**
@@ -58,7 +58,6 @@ public static <B> Builder<B> builder() {
    *
    * @since 13.0
    */
-  @Beta
   public static final class Builder<B> {
     private final ImmutableMap.Builder<TypeToken<? extends B>, B> mapBuilder =
         ImmutableMap.builder();
@@ -91,7 +90,7 @@ public <T extends B> Builder<B> put(TypeToken<T> key, T value) {
      * @throws IllegalArgumentException if duplicate keys were added
      */
     public ImmutableTypeToInstanceMap<B> build() {
-      return new ImmutableTypeToInstanceMap<B>(mapBuilder.build());
+      return new ImmutableTypeToInstanceMap<>(mapBuilder.buildOrThrow());
     }
   }
 
@@ -102,11 +101,13 @@ private ImmutableTypeToInstanceMap(ImmutableMap<TypeToken<? extends B>, B> deleg
   }
 
   @Override
+  @CheckForNull
   public <T extends B> T getInstance(TypeToken<T> type) {
     return trustedGet(type.rejectTypeVariables());
   }
 
   @Override
+  @CheckForNull
   public <T extends B> T getInstance(Class<T> type) {
     return trustedGet(TypeToken.of(type));
   }
@@ -121,6 +122,7 @@ public <T extends B> T getInstance(Class<T> type) {
   @Deprecated
   @Override
   @DoNotCall("Always throws UnsupportedOperationException")
+  @CheckForNull
   public <T extends B> T putInstance(TypeToken<T> type, T value) {
     throw new UnsupportedOperationException();
   }
@@ -135,6 +137,7 @@ public <T extends B> T putInstance(TypeToken<T> type, T value) {
   @Deprecated
   @Override
   @DoNotCall("Always throws UnsupportedOperationException")
+  @CheckForNull
   public <T extends B> T putInstance(Class<T> type, T value) {
     throw new UnsupportedOperationException();
   }
@@ -149,6 +152,7 @@ public <T extends B> T putInstance(Class<T> type, T value) {
   @Deprecated
   @Override
   @DoNotCall("Always throws UnsupportedOperationException")
+  @CheckForNull
   public B put(TypeToken<? extends B> key, B value) {
     throw new UnsupportedOperationException();
   }
@@ -172,6 +176,7 @@ protected Map<TypeToken<? extends B>, B> delegate() {
   }
 
   @SuppressWarnings("unchecked") // value could not get in if not a T
+  @CheckForNull
   private <T extends B> T trustedGet(TypeToken<T> type) {
     return (T) delegate.get(type);
   }
diff --git a/android/guava/src/com/google/common/reflect/Invokable.java b/android/guava/src/com/google/common/reflect/Invokable.java
index 3900244ae4c4..8e75aa856a3e 100644
--- a/android/guava/src/com/google/common/reflect/Invokable.java
+++ b/android/guava/src/com/google/common/reflect/Invokable.java
@@ -21,8 +21,8 @@
 import com.google.errorprone.annotations.CanIgnoreReturnValue;
 import java.lang.annotation.Annotation;
 import java.lang.reflect.AccessibleObject;
+import java.lang.reflect.AnnotatedElement;
 import java.lang.reflect.Constructor;
-import java.lang.reflect.GenericDeclaration;
 import java.lang.reflect.InvocationTargetException;
 import java.lang.reflect.Member;
 import java.lang.reflect.Method;
@@ -30,7 +30,8 @@
 import java.lang.reflect.Type;
 import java.lang.reflect.TypeVariable;
 import java.util.Arrays;
-import org.checkerframework.checker.nullness.compatqual.NullableDecl;
+import javax.annotation.CheckForNull;
+import org.checkerframework.checker.nullness.qual.Nullable;
 
 /**
  * Wrapper around either a {@link Method} or a {@link Constructor}. Convenience API is provided to
@@ -48,17 +49,29 @@
  * assertEquals(new TypeToken<List<String>>() {}, invokable.getOwnerType());
  * }</pre>
  *
+ * <p><b>Note:</b> earlier versions of this class inherited from {@link
+ * java.lang.reflect.AccessibleObject AccessibleObject} and {@link
+ * java.lang.reflect.GenericDeclaration GenericDeclaration}. Since version 31.0 that is no longer
+ * the case. However, most methods from those types are present with the same signature in this
+ * class.
+ *
  * @param <T> the type that owns this method or constructor.
  * @param <R> the return type of (or supertype thereof) the method or the declaring type of the
  *     constructor.
  * @author Ben Yu
- * @since 14.0
+ * @since 14.0 (no longer implements {@link AccessibleObject} or {@code GenericDeclaration} since
+ *     31.0)
  */
 @Beta
-public abstract class Invokable<T, R> extends Element implements GenericDeclaration {
+@ElementTypesAreNonnullByDefault
+public abstract class Invokable<T, R> implements AnnotatedElement, Member {
+  private final AccessibleObject accessibleObject;
+  private final Member member;
 
   <M extends AccessibleObject & Member> Invokable(M member) {
-    super(member);
+    checkNotNull(member);
+    this.accessibleObject = member;
+    this.member = member;
   }
 
   /** Returns {@link Invokable} of {@code method}. */
@@ -71,6 +84,151 @@ public static <T> Invokable<T, T> from(Constructor<T> constructor) {
     return new ConstructorInvokable<T>(constructor);
   }
 
+  @Override
+  public final boolean isAnnotationPresent(Class<? extends Annotation> annotationClass) {
+    return accessibleObject.isAnnotationPresent(annotationClass);
+  }
+
+  @Override
+  @CheckForNull
+  public final <A extends Annotation> A getAnnotation(Class<A> annotationClass) {
+    return accessibleObject.getAnnotation(annotationClass);
+  }
+
+  @Override
+  public final Annotation[] getAnnotations() {
+    return accessibleObject.getAnnotations();
+  }
+
+  @Override
+  public final Annotation[] getDeclaredAnnotations() {
+    return accessibleObject.getDeclaredAnnotations();
+  }
+
+  // We ought to be able to implement GenericDeclaration instead its parent AnnotatedElement.
+  // That would give us this method declaration. But for some reason, implementing
+  // GenericDeclaration leads to weird errors in Android tests:
+  // IncompatibleClassChangeError: interface not implemented
+  /** See {@link java.lang.reflect.GenericDeclaration#getTypeParameters()}. */
+  public abstract TypeVariable<?>[] getTypeParameters();
+
+  /** See {@link java.lang.reflect.AccessibleObject#setAccessible(boolean)}. */
+  public final void setAccessible(boolean flag) {
+    accessibleObject.setAccessible(flag);
+  }
+
+  /** See {@link java.lang.reflect.AccessibleObject#trySetAccessible()}. */
+  public final boolean trySetAccessible() {
+    // We can't call accessibleObject.trySetAccessible since that was added in Java 9 and this code
+    // should work on Java 8. So we emulate it this way.
+    try {
+      accessibleObject.setAccessible(true);
+      return true;
+    } catch (RuntimeException e) {
+      return false;
+    }
+  }
+
+  /** See {@link java.lang.reflect.AccessibleObject#isAccessible()}. */
+  public final boolean isAccessible() {
+    return accessibleObject.isAccessible();
+  }
+
+  @Override
+  public final String getName() {
+    return member.getName();
+  }
+
+  @Override
+  public final int getModifiers() {
+    return member.getModifiers();
+  }
+
+  @Override
+  public final boolean isSynthetic() {
+    return member.isSynthetic();
+  }
+
+  /** Returns true if the element is public. */
+  public final boolean isPublic() {
+    return Modifier.isPublic(getModifiers());
+  }
+
+  /** Returns true if the element is protected. */
+  public final boolean isProtected() {
+    return Modifier.isProtected(getModifiers());
+  }
+
+  /** Returns true if the element is package-private. */
+  public final boolean isPackagePrivate() {
+    return !isPrivate() && !isPublic() && !isProtected();
+  }
+
+  /** Returns true if the element is private. */
+  public final boolean isPrivate() {
+    return Modifier.isPrivate(getModifiers());
+  }
+
+  /** Returns true if the element is static. */
+  public final boolean isStatic() {
+    return Modifier.isStatic(getModifiers());
+  }
+
+  /**
+   * Returns {@code true} if this method is final, per {@code Modifier.isFinal(getModifiers())}.
+   *
+   * <p>Note that a method may still be effectively "final", or non-overridable when it has no
+   * {@code final} keyword. For example, it could be private, or it could be declared by a final
+   * class. To tell whether a method is overridable, use {@link Invokable#isOverridable}.
+   */
+  public final boolean isFinal() {
+    return Modifier.isFinal(getModifiers());
+  }
+
+  /** Returns true if the method is abstract. */
+  public final boolean isAbstract() {
+    return Modifier.isAbstract(getModifiers());
+  }
+
+  /** Returns true if the element is native. */
+  public final boolean isNative() {
+    return Modifier.isNative(getModifiers());
+  }
+
+  /** Returns true if the method is synchronized. */
+  public final boolean isSynchronized() {
+    return Modifier.isSynchronized(getModifiers());
+  }
+
+  /** Returns true if the field is volatile. */
+  final boolean isVolatile() {
+    return Modifier.isVolatile(getModifiers());
+  }
+
+  /** Returns true if the field is transient. */
+  final boolean isTransient() {
+    return Modifier.isTransient(getModifiers());
+  }
+
+  @Override
+  public boolean equals(@CheckForNull Object obj) {
+    if (obj instanceof Invokable) {
+      Invokable<?, ?> that = (Invokable<?, ?>) obj;
+      return getOwnerType().equals(that.getOwnerType()) && member.equals(that.member);
+    }
+    return false;
+  }
+
+  @Override
+  public int hashCode() {
+    return member.hashCode();
+  }
+
+  @Override
+  public String toString() {
+    return member.toString();
+  }
+
   /**
    * Returns {@code true} if this is an overridable method. Constructors, private, static or final
    * methods, or methods declared by final classes are not overridable.
@@ -93,10 +251,11 @@ public static <T> Invokable<T, T> from(Constructor<T> constructor) {
    *     invocation conversion.
    * @throws InvocationTargetException if the underlying method or constructor throws an exception.
    */
-  // All subclasses are owned by us and we'll make sure to get the R type right.
-  @SuppressWarnings("unchecked")
+  // All subclasses are owned by us and we'll make sure to get the R type right, including nullness.
+  @SuppressWarnings({"unchecked", "nullness"})
   @CanIgnoreReturnValue
-  public final R invoke(@NullableDecl T receiver, Object... args)
+  @CheckForNull
+  public final R invoke(@CheckForNull T receiver, @Nullable Object... args)
       throws InvocationTargetException, IllegalAccessException {
     return (R) invokeInternal(receiver, checkNotNull(args));
   }
@@ -162,18 +321,18 @@ public final <R1 extends R> Invokable<T, R1> returning(TypeToken<R1> returnType)
   @SuppressWarnings("unchecked") // The declaring class is T's raw class, or one of its supertypes.
   @Override
   public final Class<? super T> getDeclaringClass() {
-    return (Class<? super T>) super.getDeclaringClass();
+    return (Class<? super T>) member.getDeclaringClass();
   }
 
   /** Returns the type of {@code T}. */
   // Overridden in TypeToken#method() and TypeToken#constructor()
   @SuppressWarnings("unchecked") // The declaring class is T.
-  @Override
   public TypeToken<T> getOwnerType() {
     return (TypeToken<T>) TypeToken.of(getDeclaringClass());
   }
 
-  abstract Object invokeInternal(@NullableDecl Object receiver, Object[] args)
+  @CheckForNull
+  abstract Object invokeInternal(@CheckForNull Object receiver, @Nullable Object[] args)
       throws InvocationTargetException, IllegalAccessException;
 
   abstract Type[] getGenericParameterTypes();
@@ -195,7 +354,8 @@ static class MethodInvokable<T> extends Invokable<T, Object> {
     }
 
     @Override
-    final Object invokeInternal(@NullableDecl Object receiver, Object[] args)
+    @CheckForNull
+    final Object invokeInternal(@CheckForNull Object receiver, @Nullable Object[] args)
         throws InvocationTargetException, IllegalAccessException {
       return method.invoke(receiver, args);
     }
@@ -249,7 +409,7 @@ static class ConstructorInvokable<T> extends Invokable<T, T> {
     }
 
     @Override
-    final Object invokeInternal(@NullableDecl Object receiver, Object[] args)
+    final Object invokeInternal(@CheckForNull Object receiver, @Nullable Object[] args)
         throws InvocationTargetException, IllegalAccessException {
       try {
         return constructor.newInstance(args);
diff --git a/android/guava/src/com/google/common/reflect/MutableTypeToInstanceMap.java b/android/guava/src/com/google/common/reflect/MutableTypeToInstanceMap.java
index dccd2983b32c..9542e0a7ed51 100644
--- a/android/guava/src/com/google/common/reflect/MutableTypeToInstanceMap.java
+++ b/android/guava/src/com/google/common/reflect/MutableTypeToInstanceMap.java
@@ -16,8 +16,6 @@
 
 import static com.google.common.base.Preconditions.checkNotNull;
 
-import com.google.common.annotations.Beta;
-import com.google.common.base.Function;
 import com.google.common.collect.ForwardingMap;
 import com.google.common.collect.ForwardingMapEntry;
 import com.google.common.collect.ForwardingSet;
@@ -28,43 +26,47 @@
 import java.util.Iterator;
 import java.util.Map;
 import java.util.Set;
-import org.checkerframework.checker.nullness.compatqual.NullableDecl;
+import javax.annotation.CheckForNull;
+import org.checkerframework.checker.nullness.qual.Nullable;
 
 /**
  * A mutable type-to-instance map. See also {@link ImmutableTypeToInstanceMap}.
  *
+ * <p>This implementation <i>does</i> support null values, despite how it is annotated; see
+ * discussion at {@link TypeToInstanceMap}.
+ *
  * @author Ben Yu
  * @since 13.0
  */
-@Beta
+@ElementTypesAreNonnullByDefault
 public final class MutableTypeToInstanceMap<B> extends ForwardingMap<TypeToken<? extends B>, B>
     implements TypeToInstanceMap<B> {
 
   private final Map<TypeToken<? extends B>, B> backingMap = Maps.newHashMap();
 
   @Override
-  @NullableDecl
+  @CheckForNull
   public <T extends B> T getInstance(Class<T> type) {
     return trustedGet(TypeToken.of(type));
   }
 
   @Override
-  @NullableDecl
+  @CheckForNull
   public <T extends B> T getInstance(TypeToken<T> type) {
     return trustedGet(type.rejectTypeVariables());
   }
 
   @Override
   @CanIgnoreReturnValue
-  @NullableDecl
-  public <T extends B> T putInstance(Class<T> type, @NullableDecl T value) {
+  @CheckForNull
+  public <T extends B> T putInstance(Class<T> type, T value) {
     return trustedPut(TypeToken.of(type), value);
   }
 
   @Override
   @CanIgnoreReturnValue
-  @NullableDecl
-  public <T extends B> T putInstance(TypeToken<T> type, @NullableDecl T value) {
+  @CheckForNull
+  public <T extends B> T putInstance(TypeToken<T> type, T value) {
     return trustedPut(type.rejectTypeVariables(), value);
   }
 
@@ -78,6 +80,7 @@ public <T extends B> T putInstance(TypeToken<T> type, @NullableDecl T value) {
   @Deprecated
   @Override
   @DoNotCall("Always throws UnsupportedOperationException")
+  @CheckForNull
   public B put(TypeToken<? extends B> key, B value) {
     throw new UnsupportedOperationException("Please use putInstance() instead.");
   }
@@ -106,13 +109,13 @@ protected Map<TypeToken<? extends B>, B> delegate() {
   }
 
   @SuppressWarnings("unchecked") // value could not get in if not a T
-  @NullableDecl
-  private <T extends B> T trustedPut(TypeToken<T> type, @NullableDecl T value) {
+  @CheckForNull
+  private <T extends B> T trustedPut(TypeToken<T> type, T value) {
     return (T) backingMap.put(type, value);
   }
 
   @SuppressWarnings("unchecked") // value could not get in if not a T
-  @NullableDecl
+  @CheckForNull
   private <T extends B> T trustedGet(TypeToken<T> type) {
     return (T) backingMap.get(type);
   }
@@ -121,7 +124,7 @@ private static final class UnmodifiableEntry<K, V> extends ForwardingMapEntry<K,
 
     private final Entry<K, V> delegate;
 
-    static <K, V> Set<Entry<K, V>> transformEntries(final Set<Entry<K, V>> entries) {
+    static <K, V> Set<Entry<K, V>> transformEntries(Set<Entry<K, V>> entries) {
       return new ForwardingSet<Map.Entry<K, V>>() {
         @Override
         protected Set<Entry<K, V>> delegate() {
@@ -135,25 +138,27 @@ public Iterator<Entry<K, V>> iterator() {
 
         @Override
         public Object[] toArray() {
-          return standardToArray();
+          /*
+           * standardToArray returns `@Nullable Object[]` rather than `Object[]` but only because it
+           * can be used with collections that may contain null. This collection is a collection of
+           * non-null Entry objects (Entry objects that might contain null values but are not
+           * themselves null), so we can treat it as a plain `Object[]`.
+           */
+          @SuppressWarnings("nullness")
+          Object[] result = standardToArray();
+          return result;
         }
 
         @Override
-        public <T> T[] toArray(T[] array) {
+        @SuppressWarnings("nullness") // b/192354773 in our checker affects toArray declarations
+        public <T extends @Nullable Object> T[] toArray(T[] array) {
           return standardToArray(array);
         }
       };
     }
 
     private static <K, V> Iterator<Entry<K, V>> transformEntries(Iterator<Entry<K, V>> entries) {
-      return Iterators.transform(
-          entries,
-          new Function<Entry<K, V>, Entry<K, V>>() {
-            @Override
-            public Entry<K, V> apply(Entry<K, V> entry) {
-              return new UnmodifiableEntry<>(entry);
-            }
-          });
+      return Iterators.transform(entries, UnmodifiableEntry::new);
     }
 
     private UnmodifiableEntry(java.util.Map.Entry<K, V> delegate) {
diff --git a/android/guava/src/com/google/common/reflect/Parameter.java b/android/guava/src/com/google/common/reflect/Parameter.java
index 8f05ef6c22c8..a5be09d41d70 100644
--- a/android/guava/src/com/google/common/reflect/Parameter.java
+++ b/android/guava/src/com/google/common/reflect/Parameter.java
@@ -21,15 +21,21 @@
 import com.google.common.collect.ImmutableList;
 import java.lang.annotation.Annotation;
 import java.lang.reflect.AnnotatedElement;
-import org.checkerframework.checker.nullness.compatqual.NullableDecl;
+import javax.annotation.CheckForNull;
+import org.checkerframework.checker.nullness.qual.Nullable;
 
 /**
  * Represents a method or constructor parameter.
  *
+ * <p><b>Note:</b> Since Java 8 introduced {@link java.lang.reflect.Parameter} to represent method
+ * and constructor parameters, this class is no longer necessary. We intend to deprecate it in a
+ * future version.
+ *
  * @author Ben Yu
  * @since 14.0
  */
 @Beta
+@ElementTypesAreNonnullByDefault
 public final class Parameter implements AnnotatedElement {
 
   private final Invokable<?, ?> declaration;
@@ -61,7 +67,7 @@ public boolean isAnnotationPresent(Class<? extends Annotation> annotationType) {
   }
 
   @Override
-  @NullableDecl
+  @CheckForNull
   public <A extends Annotation> A getAnnotation(Class<A> annotationType) {
     checkNotNull(annotationType);
     for (Annotation annotation : annotations) {
@@ -92,7 +98,7 @@ public Annotation[] getDeclaredAnnotations() {
 
   /** @since 18.0 */
   // @Override on JDK8
-  @NullableDecl
+  @CheckForNull
   public <A extends Annotation> A getDeclaredAnnotation(Class<A> annotationType) {
     checkNotNull(annotationType);
     return FluentIterable.from(annotations).filter(annotationType).first().orNull();
@@ -101,11 +107,15 @@ public <A extends Annotation> A getDeclaredAnnotation(Class<A> annotationType) {
   /** @since 18.0 */
   // @Override on JDK8
   public <A extends Annotation> A[] getDeclaredAnnotationsByType(Class<A> annotationType) {
-    return FluentIterable.from(annotations).filter(annotationType).toArray(annotationType);
+    @Nullable
+    A[] result = FluentIterable.from(annotations).filter(annotationType).toArray(annotationType);
+    @SuppressWarnings("nullness") // safe because the input list contains no nulls
+    A[] cast = (A[]) result;
+    return cast;
   }
 
   @Override
-  public boolean equals(@NullableDecl Object obj) {
+  public boolean equals(@CheckForNull Object obj) {
     if (obj instanceof Parameter) {
       Parameter that = (Parameter) obj;
       return position == that.position && declaration.equals(that.declaration);
diff --git a/android/guava/src/com/google/common/reflect/ParametricNullness.java b/android/guava/src/com/google/common/reflect/ParametricNullness.java
new file mode 100644
index 000000000000..b6331ac26b0b
--- /dev/null
+++ b/android/guava/src/com/google/common/reflect/ParametricNullness.java
@@ -0,0 +1,52 @@
+/*
+ * Copyright (C) 2021 The Guava Authors
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package com.google.common.reflect;
+
+import static java.lang.annotation.ElementType.FIELD;
+import static java.lang.annotation.ElementType.METHOD;
+import static java.lang.annotation.ElementType.PARAMETER;
+import static java.lang.annotation.RetentionPolicy.RUNTIME;
+
+import com.google.common.annotations.GwtCompatible;
+import java.lang.annotation.Retention;
+import java.lang.annotation.Target;
+
+/**
+ * Marks a "top-level" type-variable usage as the closest we can get to "non-nullable when
+ * non-nullable; nullable when nullable" (like the Android <a
+ * href="https://android.googlesource.com/platform/libcore/+/master/luni/src/main/java/libcore/util/NullFromTypeParam.java">{@code
+ * NullFromTypeParam}</a>).
+ *
+ * <p>Consumers of this annotation include:
+ *
+ * <ul>
+ *   <li>Kotlin, for which it makes the type-variable usage (a) a Kotlin platform type when the type
+ *       argument is non-nullable and (b) nullable when the type argument is nullable. We use this
+ *       to "undo" {@link ElementTypesAreNonnullByDefault}.
+ *   <li><a href="https://developers.google.com/j2objc">J2ObjC</a>
+ *   <li>{@code NullPointerTester}, at least in the Android backport (where the type-use annotations
+ *       {@code NullPointerTester} would need are not available) and in case of <a
+ *       href="https://bugs.openjdk.java.net/browse/JDK-8202469">JDK-8202469</a>
+ * </ul>
+ *
+ */
+@GwtCompatible
+@Retention(RUNTIME)
+@Target({FIELD, METHOD, PARAMETER})
+@javax.annotation.meta.TypeQualifierNickname
+@javax.annotation.Nonnull(when = javax.annotation.meta.When.UNKNOWN)
+@interface ParametricNullness {}
diff --git a/android/guava/src/com/google/common/reflect/Reflection.java b/android/guava/src/com/google/common/reflect/Reflection.java
index 4ad5dff78a72..9544963481d9 100644
--- a/android/guava/src/com/google/common/reflect/Reflection.java
+++ b/android/guava/src/com/google/common/reflect/Reflection.java
@@ -17,7 +17,6 @@
 import static com.google.common.base.Preconditions.checkArgument;
 import static com.google.common.base.Preconditions.checkNotNull;
 
-import com.google.common.annotations.Beta;
 import java.lang.reflect.InvocationHandler;
 import java.lang.reflect.Proxy;
 
@@ -26,7 +25,7 @@
  *
  * @since 12.0
  */
-@Beta
+@ElementTypesAreNonnullByDefault
 public final class Reflection {
 
   /**
diff --git a/android/guava/src/com/google/common/reflect/TypeCapture.java b/android/guava/src/com/google/common/reflect/TypeCapture.java
index effb382b2826..2be7b4fddad1 100644
--- a/android/guava/src/com/google/common/reflect/TypeCapture.java
+++ b/android/guava/src/com/google/common/reflect/TypeCapture.java
@@ -24,6 +24,7 @@
  *
  * @author Ben Yu
  */
+@ElementTypesAreNonnullByDefault
 abstract class TypeCapture<T> {
 
   /** Returns the captured type. */
diff --git a/android/guava/src/com/google/common/reflect/TypeParameter.java b/android/guava/src/com/google/common/reflect/TypeParameter.java
index 283494107d93..69cd8291a909 100644
--- a/android/guava/src/com/google/common/reflect/TypeParameter.java
+++ b/android/guava/src/com/google/common/reflect/TypeParameter.java
@@ -16,10 +16,9 @@
 
 import static com.google.common.base.Preconditions.checkArgument;
 
-import com.google.common.annotations.Beta;
 import java.lang.reflect.Type;
 import java.lang.reflect.TypeVariable;
-import org.checkerframework.checker.nullness.compatqual.NullableDecl;
+import javax.annotation.CheckForNull;
 
 /**
  * Captures a free type variable that can be used in {@link TypeToken#where}. For example:
@@ -34,7 +33,17 @@
  * @author Ben Yu
  * @since 12.0
  */
-@Beta
+@ElementTypesAreNonnullByDefault
+/*
+ * A nullable bound would let users create a TypeParameter instance for a parameter with a nullable
+ * bound. However, it would also let them create `new TypeParameter<@Nullable T>() {}`, which
+ * wouldn't behave as users might expect. Additionally, it's not clear how the TypeToken API could
+ * support even a "normal" `TypeParameter<T>` when `<T>` has a nullable bound. (See the discussion
+ * on TypeToken.where.) So, in the interest of failing fast and encouraging the user to switch to a
+ * non-null bound if possible, let's require a non-null bound here.
+ *
+ * TODO(cpovirk): Elaborate on "wouldn't behave as users might expect."
+ */
 public abstract class TypeParameter<T> extends TypeCapture<T> {
 
   final TypeVariable<?> typeVariable;
@@ -51,7 +60,7 @@ public final int hashCode() {
   }
 
   @Override
-  public final boolean equals(@NullableDecl Object o) {
+  public final boolean equals(@CheckForNull Object o) {
     if (o instanceof TypeParameter) {
       TypeParameter<?> that = (TypeParameter<?>) o;
       return typeVariable.equals(that.typeVariable);
diff --git a/android/guava/src/com/google/common/reflect/TypeResolver.java b/android/guava/src/com/google/common/reflect/TypeResolver.java
index 0c18a1dbee07..32517eb8782f 100644
--- a/android/guava/src/com/google/common/reflect/TypeResolver.java
+++ b/android/guava/src/com/google/common/reflect/TypeResolver.java
@@ -19,7 +19,6 @@
 import static com.google.common.base.Preconditions.checkState;
 import static java.util.Arrays.asList;
 
-import com.google.common.annotations.Beta;
 import com.google.common.base.Joiner;
 import com.google.common.base.Objects;
 import com.google.common.collect.ImmutableMap;
@@ -35,7 +34,7 @@
 import java.util.Map.Entry;
 import java.util.Set;
 import java.util.concurrent.atomic.AtomicInteger;
-import org.checkerframework.checker.nullness.compatqual.NullableDecl;
+import javax.annotation.CheckForNull;
 
 /**
  * An object of this class encapsulates type mappings from type variables. Mappings are established
@@ -51,7 +50,7 @@
  * @author Ben Yu
  * @since 15.0
  */
-@Beta
+@ElementTypesAreNonnullByDefault
 public final class TypeResolver {
 
   private final TypeTable typeTable;
@@ -122,7 +121,7 @@ TypeResolver where(Map<TypeVariableKey, ? extends Type> mappings) {
   }
 
   private static void populateTypeMappings(
-      final Map<TypeVariableKey, Type> mappings, final Type from, final Type to) {
+      Map<TypeVariableKey, Type> mappings, Type from, Type to) {
     if (from.equals(to)) {
       return;
     }
@@ -295,11 +294,11 @@ final TypeTable where(Map<TypeVariableKey, ? extends Type> mappings) {
         checkArgument(!variable.equalsType(type), "Type variable %s bound to itself", variable);
         builder.put(variable, type);
       }
-      return new TypeTable(builder.build());
+      return new TypeTable(builder.buildOrThrow());
     }
 
-    final Type resolve(final TypeVariable<?> var) {
-      final TypeTable unguarded = this;
+    final Type resolve(TypeVariable<?> var) {
+      TypeTable unguarded = this;
       TypeTable guarded =
           new TypeTable() {
             @Override
@@ -413,7 +412,7 @@ void visitWildcardType(WildcardType t) {
       visit(t.getUpperBounds());
     }
 
-    private void map(final TypeVariableKey var, final Type arg) {
+    private void map(TypeVariableKey var, Type arg) {
       if (mappings.containsKey(var)) {
         // Mapping already established
         // This is possible when following both superClass -> enclosingClass
@@ -503,12 +502,12 @@ TypeVariable<?> captureAsTypeVariable(Type[] upperBounds) {
       return Types.newArtificialTypeVariable(WildcardCapturer.class, name, upperBounds);
     }
 
-    private WildcardCapturer forTypeVariable(final TypeVariable<?> typeParam) {
+    private WildcardCapturer forTypeVariable(TypeVariable<?> typeParam) {
       return new WildcardCapturer(id) {
         @Override
         TypeVariable<?> captureAsTypeVariable(Type[] upperBounds) {
           Set<Type> combined = new LinkedHashSet<>(asList(upperBounds));
-          // Since this is an artifically generated type variable, we don't bother checking
+          // Since this is an artificially generated type variable, we don't bother checking
           // subtyping between declared type bound and actual type bound. So it's possible that we
           // may generate something like <capture#1-of ? extends Foo&SubFoo>.
           // Checking subtype between declared and actual type bounds
@@ -527,7 +526,8 @@ private WildcardCapturer notForTypeVariable() {
       return new WildcardCapturer(id);
     }
 
-    private Type captureNullable(@NullableDecl Type type) {
+    @CheckForNull
+    private Type captureNullable(@CheckForNull Type type) {
       if (type == null) {
         return null;
       }
@@ -561,7 +561,7 @@ public int hashCode() {
     }
 
     @Override
-    public boolean equals(Object obj) {
+    public boolean equals(@CheckForNull Object obj) {
       if (obj instanceof TypeVariableKey) {
         TypeVariableKey that = (TypeVariableKey) obj;
         return equalsTypeVariable(that.var);
@@ -576,6 +576,7 @@ public String toString() {
     }
 
     /** Wraps {@code t} in a {@code TypeVariableKey} if it's a type variable. */
+    @CheckForNull
     static TypeVariableKey forLookup(Type t) {
       if (t instanceof TypeVariable) {
         return new TypeVariableKey((TypeVariable<?>) t);
diff --git a/android/guava/src/com/google/common/reflect/TypeToInstanceMap.java b/android/guava/src/com/google/common/reflect/TypeToInstanceMap.java
index 80396bc7893f..8a418df2a4d3 100644
--- a/android/guava/src/com/google/common/reflect/TypeToInstanceMap.java
+++ b/android/guava/src/com/google/common/reflect/TypeToInstanceMap.java
@@ -14,11 +14,10 @@
 
 package com.google.common.reflect;
 
-import com.google.common.annotations.Beta;
 import com.google.errorprone.annotations.CanIgnoreReturnValue;
 import com.google.errorprone.annotations.DoNotMock;
 import java.util.Map;
-import org.checkerframework.checker.nullness.compatqual.NullableDecl;
+import javax.annotation.CheckForNull;
 
 /**
  * A map, each entry of which maps a {@link TypeToken} to an instance of that type. In addition to
@@ -35,12 +34,15 @@
  * <p>Like any other {@code Map<Class, Object>}, this map may contain entries for primitive types,
  * and a primitive type and its corresponding wrapper type may map to different values.
  *
+ * <p>This class's support for {@code null} requires some explanation. For details, see {@link
+ * ClassToInstanceMap}. Its explanation applies equally well to {@code TypeToInstanceMap}.
+ *
  * @param <B> the common supertype that all entries must share; often this is simply {@link Object}
  * @author Ben Yu
  * @since 13.0
  */
-@Beta
 @DoNotMock("Use ImmutableTypeToInstanceMap or MutableTypeToInstanceMap")
+@ElementTypesAreNonnullByDefault
 public interface TypeToInstanceMap<B> extends Map<TypeToken<? extends B>, B> {
 
   /**
@@ -51,7 +53,7 @@ public interface TypeToInstanceMap<B> extends Map<TypeToken<? extends B>, B> {
    * <p>{@code getInstance(Foo.class)} is equivalent to {@code
    * getInstance(TypeToken.of(Foo.class))}.
    */
-  @NullableDecl
+  @CheckForNull
   <T extends B> T getInstance(Class<T> type);
 
   /**
@@ -59,7 +61,7 @@ public interface TypeToInstanceMap<B> extends Map<TypeToken<? extends B>, B> {
    * present. This will only return a value that was bound to this specific type, not a value that
    * may have been bound to a subtype.
    */
-  @NullableDecl
+  @CheckForNull
   <T extends B> T getInstance(TypeToken<T> type);
 
   /**
@@ -73,8 +75,8 @@ public interface TypeToInstanceMap<B> extends Map<TypeToken<? extends B>, B> {
    *     null} if there was no previous entry.
    */
   @CanIgnoreReturnValue
-  @NullableDecl
-  <T extends B> T putInstance(Class<T> type, @NullableDecl T value);
+  @CheckForNull
+  <T extends B> T putInstance(Class<T> type, T value);
 
   /**
    * Maps the specified type to the specified value. Does <i>not</i> associate this value with any
@@ -84,6 +86,6 @@ public interface TypeToInstanceMap<B> extends Map<TypeToken<? extends B>, B> {
    *     if there was no previous entry.
    */
   @CanIgnoreReturnValue
-  @NullableDecl
-  <T extends B> T putInstance(TypeToken<T> type, @NullableDecl T value);
+  @CheckForNull
+  <T extends B> T putInstance(TypeToken<T> type, T value);
 }
diff --git a/android/guava/src/com/google/common/reflect/TypeToken.java b/android/guava/src/com/google/common/reflect/TypeToken.java
index daf498c3db49..fea1d53a2fab 100644
--- a/android/guava/src/com/google/common/reflect/TypeToken.java
+++ b/android/guava/src/com/google/common/reflect/TypeToken.java
@@ -17,6 +17,7 @@
 import static com.google.common.base.Preconditions.checkArgument;
 import static com.google.common.base.Preconditions.checkNotNull;
 import static com.google.common.base.Preconditions.checkState;
+import static java.util.Objects.requireNonNull;
 
 import com.google.common.annotations.Beta;
 import com.google.common.annotations.VisibleForTesting;
@@ -46,7 +47,7 @@
 import java.util.List;
 import java.util.Map;
 import java.util.Set;
-import org.checkerframework.checker.nullness.compatqual.NullableDecl;
+import javax.annotation.CheckForNull;
 
 /**
  * A {@link Type} with generics.
@@ -96,17 +97,17 @@
  * @author Ben Yu
  * @since 12.0
  */
-@Beta
 @SuppressWarnings("serial") // SimpleTypeToken is the serialized form.
+@ElementTypesAreNonnullByDefault
 public abstract class TypeToken<T> extends TypeCapture<T> implements Serializable {
 
   private final Type runtimeType;
 
   /** Resolver for resolving parameter and field types with {@link #runtimeType} as context. */
-  @NullableDecl private transient TypeResolver invariantTypeResolver;
+  @CheckForNull private transient TypeResolver invariantTypeResolver;
 
   /** Resolver for resolving covariant types with {@link #runtimeType} as context. */
-  @NullableDecl private transient TypeResolver covariantTypeResolver;
+  @CheckForNull private transient TypeResolver covariantTypeResolver;
 
   /**
    * Constructs a new type token of {@code T}.
@@ -166,7 +167,7 @@ private TypeToken(Type type) {
 
   /** Returns an instance of type token that wraps {@code type}. */
   public static <T> TypeToken<T> of(Class<T> type) {
-    return new SimpleTypeToken<T>(type);
+    return new SimpleTypeToken<>(type);
   }
 
   /** Returns an instance of type token that wraps {@code type}. */
@@ -220,6 +221,17 @@ public final Type getType() {
    * @param typeParam the parameter type variable
    * @param typeArg the actual type to substitute
    */
+  /*
+   * TODO(cpovirk): Is there any way for us to support TypeParameter instances for type parameters
+   * that have nullable bounds? Unfortunately, if we change the parameter to TypeParameter<? extends
+   * @Nullable X>, then users might pass a TypeParameter<Y>, where Y is a subtype of X, while still
+   * passing a TypeToken<X>. This would be invalid. Maybe we could accept a TypeParameter<@PolyNull
+   * X> if we support such a thing? It would be weird or misleading for users to be able to pass
+   * `new TypeParameter<@Nullable T>() {}` and have it act as a plain `TypeParameter<T>`, but
+   * hopefully no one would do that, anyway. See also the comment on TypeParameter itself.
+   *
+   * TODO(cpovirk): Elaborate on this / merge with other comment?
+   */
   public final <X> TypeToken<T> where(TypeParameter<X> typeParam, TypeToken<X> typeArg) {
     TypeResolver resolver =
         new TypeResolver()
@@ -227,7 +239,7 @@ public final <X> TypeToken<T> where(TypeParameter<X> typeParam, TypeToken<X> typ
                 ImmutableMap.of(
                     new TypeResolver.TypeVariableKey(typeParam.typeVariable), typeArg.runtimeType));
     // If there's any type error, we'd report now rather than later.
-    return new SimpleTypeToken<T>(resolver.resolveType(runtimeType));
+    return new SimpleTypeToken<>(resolver.resolveType(runtimeType));
   }
 
   /**
@@ -248,6 +260,10 @@ public final <X> TypeToken<T> where(TypeParameter<X> typeParam, TypeToken<X> typ
    * @param typeParam the parameter type variable
    * @param typeArg the actual type to substitute
    */
+  /*
+   * TODO(cpovirk): Is there any way for us to support TypeParameter instances for type parameters
+   * that have nullable bounds? See discussion on the other overload of this method.
+   */
   public final <X> TypeToken<T> where(TypeParameter<X> typeParam, Class<X> typeArg) {
     return where(typeParam, of(typeArg));
   }
@@ -288,7 +304,7 @@ private TypeToken<?> resolveSupertype(Type type) {
    * if the bound is a class or extends from a class. This means that the returned type could be a
    * type variable too.
    */
-  @NullableDecl
+  @CheckForNull
   final TypeToken<? super T> getGenericSuperclass() {
     if (runtimeType instanceof TypeVariable) {
       // First bound is always the super class, if one exists.
@@ -307,7 +323,7 @@ final TypeToken<? super T> getGenericSuperclass() {
     return superToken;
   }
 
-  @NullableDecl
+  @CheckForNull
   private TypeToken<? super T> boundAsSuperclass(Type bound) {
     TypeToken<?> token = of(bound);
     if (token.getRawType().isInterface()) {
@@ -560,7 +576,7 @@ public final TypeToken<T> unwrap() {
    * Returns the array component type if this type represents an array ({@code int[]}, {@code T[]},
    * {@code <? extends Map<String, Integer>[]>} etc.), or else {@code null} is returned.
    */
-  @NullableDecl
+  @CheckForNull
   public final TypeToken<?> getComponentType() {
     Type componentType = Types.getComponentType(runtimeType);
     if (componentType == null) {
@@ -574,6 +590,7 @@ public final TypeToken<?> getComponentType() {
    *
    * @since 14.0
    */
+  @Beta
   public final Invokable<T, Object> method(Method method) {
     checkArgument(
         this.someRawTypeIsSubclassOf(method.getDeclaringClass()),
@@ -613,6 +630,7 @@ public String toString() {
    *
    * @since 14.0
    */
+  @Beta
   public final Invokable<T, T> constructor(Constructor<?> constructor) {
     checkArgument(
         constructor.getDeclaringClass() == getRawType(),
@@ -655,7 +673,7 @@ public String toString() {
    */
   public class TypeSet extends ForwardingSet<TypeToken<? super T>> implements Serializable {
 
-    @NullableDecl private transient ImmutableSet<TypeToken<? super T>> types;
+    @CheckForNull private transient ImmutableSet<TypeToken<? super T>> types;
 
     TypeSet() {}
 
@@ -701,7 +719,7 @@ public Set<Class<? super T>> rawTypes() {
   private final class InterfaceSet extends TypeSet {
 
     private final transient TypeSet allTypes;
-    @NullableDecl private transient ImmutableSet<TypeToken<? super T>> interfaces;
+    @CheckForNull private transient ImmutableSet<TypeToken<? super T>> interfaces;
 
     InterfaceSet(TypeSet allTypes) {
       this.allTypes = allTypes;
@@ -729,15 +747,7 @@ public Set<Class<? super T>> rawTypes() {
       @SuppressWarnings({"unchecked", "rawtypes"})
       ImmutableList<Class<? super T>> collectedTypes =
           (ImmutableList) TypeCollector.FOR_RAW_TYPE.collectTypes(getRawTypes());
-      return FluentIterable.from(collectedTypes)
-          .filter(
-              new Predicate<Class<?>>() {
-                @Override
-                public boolean apply(Class<?> type) {
-                  return type.isInterface();
-                }
-              })
-          .toSet();
+      return FluentIterable.from(collectedTypes).filter(Class::isInterface).toSet();
     }
 
     @Override
@@ -754,7 +764,7 @@ private Object readResolve() {
 
   private final class ClassSet extends TypeSet {
 
-    @NullableDecl private transient ImmutableSet<TypeToken<? super T>> classes;
+    @CheckForNull private transient ImmutableSet<TypeToken<? super T>> classes;
 
     @Override
     protected Set<TypeToken<? super T>> delegate() {
@@ -819,7 +829,7 @@ public boolean apply(TypeToken<?> type) {
    * Returns true if {@code o} is another {@code TypeToken} that represents the same {@link Type}.
    */
   @Override
-  public boolean equals(@NullableDecl Object o) {
+  public boolean equals(@CheckForNull Object o) {
     if (o instanceof TypeToken) {
       TypeToken<?> that = (TypeToken<?>) o;
       return runtimeType.equals(that.runtimeType);
@@ -1086,7 +1096,7 @@ boolean isSupertypeOf(Type subtype) {
   }
 
   private ImmutableSet<Class<? super T>> getRawTypes() {
-    final ImmutableSet.Builder<Class<?>> builder = ImmutableSet.builder();
+    ImmutableSet.Builder<Class<?>> builder = ImmutableSet.builder();
     new TypeVisitor() {
       @Override
       void visitTypeVariable(TypeVariable<?> t) {
@@ -1133,7 +1143,7 @@ private boolean isOwnedBySubtypeOf(Type supertype) {
    * Returns the owner type of a {@link ParameterizedType} or enclosing class of a {@link Class}, or
    * null otherwise.
    */
-  @NullableDecl
+  @CheckForNull
   private Type getOwnerTypeIfPresent() {
     if (runtimeType instanceof ParameterizedType) {
       return ((ParameterizedType) runtimeType).getOwnerType();
@@ -1223,11 +1233,19 @@ private TypeToken<? super T> getArraySupertype(Class<? super T> supertype) {
     // with component type, we have lost generic type information
     // Use raw type so that compiler allows us to call getSupertype()
     @SuppressWarnings("rawtypes")
-    TypeToken componentType =
-        checkNotNull(getComponentType(), "%s isn't a super type of %s", supertype, this);
+    TypeToken componentType = getComponentType();
+    // TODO(cpovirk): checkArgument?
+    if (componentType == null) {
+      throw new IllegalArgumentException(supertype + " isn't a super type of " + this);
+    }
     // array is covariant. component type is super type, so is the array type.
     @SuppressWarnings("unchecked") // going from raw type back to generics
-    TypeToken<?> componentSupertype = componentType.getSupertype(supertype.getComponentType());
+    /*
+     * requireNonNull is safe because we call getArraySupertype only after checking
+     * supertype.isArray().
+     */
+    TypeToken<?> componentSupertype =
+        componentType.getSupertype(requireNonNull(supertype.getComponentType()));
     @SuppressWarnings("unchecked") // component type is super type, so is array type.
     TypeToken<? super T> result =
         (TypeToken<? super T>)
@@ -1237,8 +1255,14 @@ private TypeToken<? super T> getArraySupertype(Class<? super T> supertype) {
   }
 
   private TypeToken<? extends T> getArraySubtype(Class<?> subclass) {
+    Class<?> subclassComponentType = subclass.getComponentType();
+    if (subclassComponentType == null) {
+      throw new IllegalArgumentException(subclass + " does not appear to be a subtype of " + this);
+    }
     // array is covariant. component type is subtype, so is the array type.
-    TypeToken<?> componentSubtype = getComponentType().getSubtype(subclass.getComponentType());
+    // requireNonNull is safe because we call getArraySubtype only when isArray().
+    TypeToken<?> componentSubtype =
+        requireNonNull(getComponentType()).getSubtype(subclassComponentType);
     @SuppressWarnings("unchecked") // component type is subtype, so is array type.
     TypeToken<? extends T> result =
         (TypeToken<? extends T>)
@@ -1311,7 +1335,7 @@ Iterable<? extends TypeToken<?>> getInterfaces(TypeToken<?> type) {
           }
 
           @Override
-          @NullableDecl
+          @CheckForNull
           TypeToken<?> getSuperclass(TypeToken<?> type) {
             return type.getGenericSuperclass();
           }
@@ -1330,7 +1354,7 @@ Iterable<? extends Class<?>> getInterfaces(Class<?> type) {
           }
 
           @Override
-          @NullableDecl
+          @CheckForNull
           Class<?> getSuperclass(Class<?> type) {
             return type.getSuperclass();
           }
@@ -1397,12 +1421,14 @@ private int collectTypes(K type, Map<? super K, Integer> map) {
     }
 
     private static <K, V> ImmutableList<K> sortKeysByValue(
-        final Map<K, V> map, final Comparator<? super V> valueComparator) {
+        Map<K, V> map, Comparator<? super V> valueComparator) {
       Ordering<K> keyOrdering =
           new Ordering<K>() {
             @Override
             public int compare(K left, K right) {
-              return valueComparator.compare(map.get(left), map.get(right));
+              // requireNonNull is safe because we are passing keys in the map.
+              return valueComparator.compare(
+                  requireNonNull(map.get(left)), requireNonNull(map.get(right)));
             }
           };
       return keyOrdering.immutableSortedCopy(map.keySet());
@@ -1412,7 +1438,7 @@ public int compare(K left, K right) {
 
     abstract Iterable<? extends K> getInterfaces(K type);
 
-    @NullableDecl
+    @CheckForNull
     abstract K getSuperclass(K type);
 
     private static class ForwardingTypeCollector<K> extends TypeCollector<K> {
@@ -1434,6 +1460,7 @@ Iterable<? extends K> getInterfaces(K type) {
       }
 
       @Override
+      @CheckForNull
       K getSuperclass(K type) {
         return delegate.getSuperclass(type);
       }
diff --git a/android/guava/src/com/google/common/reflect/TypeVisitor.java b/android/guava/src/com/google/common/reflect/TypeVisitor.java
index 3e8436dad189..416397bc77d6 100644
--- a/android/guava/src/com/google/common/reflect/TypeVisitor.java
+++ b/android/guava/src/com/google/common/reflect/TypeVisitor.java
@@ -21,6 +21,7 @@
 import java.lang.reflect.TypeVariable;
 import java.lang.reflect.WildcardType;
 import java.util.Set;
+import org.checkerframework.checker.nullness.qual.Nullable;
 
 /**
  * Based on what a {@link Type} is, dispatch it to the corresponding {@code visit*} method. By
@@ -53,6 +54,7 @@
  *
  * @author Ben Yu
  */
+@ElementTypesAreNonnullByDefault
 abstract class TypeVisitor {
 
   private final Set<Type> visited = Sets.newHashSet();
@@ -61,7 +63,7 @@ abstract class TypeVisitor {
    * Visits the given types. Null types are ignored. This allows subclasses to call {@code
    * visit(parameterizedType.getOwnerType())} safely without having to check nulls.
    */
-  public final void visit(Type... types) {
+  public final void visit(@Nullable Type... types) {
     for (Type type : types) {
       if (type == null || !visited.add(type)) {
         // null owner type, or already visited;
diff --git a/android/guava/src/com/google/common/reflect/Types.java b/android/guava/src/com/google/common/reflect/Types.java
index 4fc39109ae3b..e69b42a8e8a0 100644
--- a/android/guava/src/com/google/common/reflect/Types.java
+++ b/android/guava/src/com/google/common/reflect/Types.java
@@ -17,9 +17,9 @@
 import static com.google.common.base.Preconditions.checkArgument;
 import static com.google.common.base.Preconditions.checkNotNull;
 import static com.google.common.collect.Iterables.transform;
+import static java.util.Objects.requireNonNull;
 
 import com.google.common.annotations.VisibleForTesting;
-import com.google.common.base.Function;
 import com.google.common.base.Joiner;
 import com.google.common.base.Objects;
 import com.google.common.base.Predicates;
@@ -44,24 +44,18 @@
 import java.util.Collection;
 import java.util.Map.Entry;
 import java.util.concurrent.atomic.AtomicReference;
-import org.checkerframework.checker.nullness.compatqual.NullableDecl;
+import javax.annotation.CheckForNull;
+import org.checkerframework.checker.nullness.qual.Nullable;
 
 /**
  * Utilities for working with {@link Type}.
  *
  * @author Ben Yu
  */
+@ElementTypesAreNonnullByDefault
 final class Types {
 
   /** Class#toString without the "class " and "interface " prefixes */
-  private static final Function<Type, String> TYPE_NAME =
-      new Function<Type, String>() {
-        @Override
-        public String apply(Type from) {
-          return JavaVersion.CURRENT.typeName(from);
-        }
-      };
-
   private static final Joiner COMMA_JOINER = Joiner.on(", ").useForNull("null");
 
   /** Returns the array type of {@code componentType}. */
@@ -86,7 +80,7 @@ static Type newArrayType(Type componentType) {
    * {@code ownerType}.
    */
   static ParameterizedType newParameterizedTypeWithOwner(
-      @NullableDecl Type ownerType, Class<?> rawType, Type... arguments) {
+      @CheckForNull Type ownerType, Class<?> rawType, Type... arguments) {
     if (ownerType == null) {
       return newParameterizedType(rawType, arguments);
     }
@@ -106,14 +100,14 @@ static ParameterizedType newParameterizedType(Class<?> rawType, Type... argument
   private enum ClassOwnership {
     OWNED_BY_ENCLOSING_CLASS {
       @Override
-      @NullableDecl
+      @CheckForNull
       Class<?> getOwnerType(Class<?> rawType) {
         return rawType.getEnclosingClass();
       }
     },
     LOCAL_CLASS_HAS_NO_OWNER {
       @Override
-      @NullableDecl
+      @CheckForNull
       Class<?> getOwnerType(Class<?> rawType) {
         if (rawType.isLocalClass()) {
           return null;
@@ -123,7 +117,7 @@ Class<?> getOwnerType(Class<?> rawType) {
       }
     };
 
-    @NullableDecl
+    @CheckForNull
     abstract Class<?> getOwnerType(Class<?> rawType);
 
     static final ClassOwnership JVM_BEHAVIOR = detectJvmBehavior();
@@ -131,7 +125,9 @@ Class<?> getOwnerType(Class<?> rawType) {
     private static ClassOwnership detectJvmBehavior() {
       class LocalClass<T> {}
       Class<?> subclass = new LocalClass<String>() {}.getClass();
-      ParameterizedType parameterizedType = (ParameterizedType) subclass.getGenericSuperclass();
+      // requireNonNull is safe because we're examining a type that's known to have a superclass.
+      ParameterizedType parameterizedType =
+          requireNonNull((ParameterizedType) subclass.getGenericSuperclass());
       for (ClassOwnership behavior : ClassOwnership.values()) {
         if (behavior.getOwnerType(LocalClass.class) == parameterizedType.getOwnerType()) {
           return behavior;
@@ -172,10 +168,10 @@ static String toString(Type type) {
     return (type instanceof Class) ? ((Class<?>) type).getName() : type.toString();
   }
 
-  @NullableDecl
+  @CheckForNull
   static Type getComponentType(Type type) {
     checkNotNull(type);
-    final AtomicReference<Type> result = new AtomicReference<>();
+    AtomicReference<@Nullable Type> result = new AtomicReference<>();
     new TypeVisitor() {
       @Override
       void visitTypeVariable(TypeVariable<?> t) {
@@ -204,7 +200,7 @@ void visitClass(Class<?> t) {
    * Returns {@code ? extends X} if any of {@code bounds} is a subtype of {@code X[]}; or null
    * otherwise.
    */
-  @NullableDecl
+  @CheckForNull
   private static Type subtypeOfComponentType(Type[] bounds) {
     for (Type bound : bounds) {
       Type componentType = getComponentType(bound);
@@ -247,7 +243,7 @@ public int hashCode() {
     }
 
     @Override
-    public boolean equals(Object obj) {
+    public boolean equals(@CheckForNull Object obj) {
       if (obj instanceof GenericArrayType) {
         GenericArrayType that = (GenericArrayType) obj;
         return Objects.equal(getGenericComponentType(), that.getGenericComponentType());
@@ -260,11 +256,11 @@ public boolean equals(Object obj) {
 
   private static final class ParameterizedTypeImpl implements ParameterizedType, Serializable {
 
-    @NullableDecl private final Type ownerType;
+    @CheckForNull private final Type ownerType;
     private final ImmutableList<Type> argumentsList;
     private final Class<?> rawType;
 
-    ParameterizedTypeImpl(@NullableDecl Type ownerType, Class<?> rawType, Type[] typeArguments) {
+    ParameterizedTypeImpl(@CheckForNull Type ownerType, Class<?> rawType, Type[] typeArguments) {
       checkNotNull(rawType);
       checkArgument(typeArguments.length == rawType.getTypeParameters().length);
       disallowPrimitiveType(typeArguments, "type parameter");
@@ -284,6 +280,7 @@ public Type getRawType() {
     }
 
     @Override
+    @CheckForNull
     public Type getOwnerType() {
       return ownerType;
     }
@@ -297,7 +294,7 @@ public String toString() {
       return builder
           .append(rawType.getName())
           .append('<')
-          .append(COMMA_JOINER.join(transform(argumentsList, TYPE_NAME)))
+          .append(COMMA_JOINER.join(transform(argumentsList, JavaVersion.CURRENT::typeName)))
           .append('>')
           .toString();
     }
@@ -310,7 +307,7 @@ public int hashCode() {
     }
 
     @Override
-    public boolean equals(Object other) {
+    public boolean equals(@CheckForNull Object other) {
       if (!(other instanceof ParameterizedType)) {
         return false;
       }
@@ -325,8 +322,7 @@ public boolean equals(Object other) {
 
   private static <D extends GenericDeclaration> TypeVariable<D> newTypeVariableImpl(
       D genericDeclaration, String name, Type[] bounds) {
-    TypeVariableImpl<D> typeVariableImpl =
-        new TypeVariableImpl<D>(genericDeclaration, name, bounds);
+    TypeVariableImpl<D> typeVariableImpl = new TypeVariableImpl<>(genericDeclaration, name, bounds);
     @SuppressWarnings("unchecked")
     TypeVariable<D> typeVariable =
         Reflection.newProxy(
@@ -376,7 +372,7 @@ private static final class TypeVariableInvocationHandler implements InvocationHa
           builder.put(method.getName(), method);
         }
       }
-      typeVariableMethods = builder.build();
+      typeVariableMethods = builder.buildKeepingLast();
     }
 
     private final TypeVariableImpl<?> typeVariableImpl;
@@ -386,7 +382,9 @@ private static final class TypeVariableInvocationHandler implements InvocationHa
     }
 
     @Override
-    public Object invoke(Object proxy, Method method, Object[] args) throws Throwable {
+    @CheckForNull
+    public Object invoke(Object proxy, Method method, @CheckForNull @Nullable Object[] args)
+        throws Throwable {
       String methodName = method.getName();
       Method typeVariableMethod = typeVariableMethods.get(methodName);
       if (typeVariableMethod == null) {
@@ -441,7 +439,7 @@ public int hashCode() {
     }
 
     @Override
-    public boolean equals(Object obj) {
+    public boolean equals(@CheckForNull Object obj) {
       if (NativeTypeVariableEquals.NATIVE_TYPE_VARIABLE_ONLY) {
         // equal only to our TypeVariable implementation with identical bounds
         if (obj != null
@@ -490,7 +488,7 @@ public Type[] getUpperBounds() {
     }
 
     @Override
-    public boolean equals(Object obj) {
+    public boolean equals(@CheckForNull Object obj) {
       if (obj instanceof WildcardType) {
         WildcardType that = (WildcardType) obj;
         return lowerBounds.equals(Arrays.asList(that.getLowerBounds()))
diff --git a/android/guava/src/com/google/common/util/concurrent/AbstractCatchingFuture.java b/android/guava/src/com/google/common/util/concurrent/AbstractCatchingFuture.java
index 740a0d535ee6..76eada214052 100644
--- a/android/guava/src/com/google/common/util/concurrent/AbstractCatchingFuture.java
+++ b/android/guava/src/com/google/common/util/concurrent/AbstractCatchingFuture.java
@@ -17,6 +17,7 @@
 import static com.google.common.base.Preconditions.checkNotNull;
 import static com.google.common.util.concurrent.Futures.getDone;
 import static com.google.common.util.concurrent.MoreExecutors.rejectionPropagatingExecutor;
+import static com.google.common.util.concurrent.NullnessCasts.uncheckedCastNullableTToT;
 import static com.google.common.util.concurrent.Platform.isInstanceOfThrowableClass;
 
 import com.google.common.annotations.GwtCompatible;
@@ -26,13 +27,17 @@
 import com.google.errorprone.annotations.ForOverride;
 import java.util.concurrent.ExecutionException;
 import java.util.concurrent.Executor;
-import org.checkerframework.checker.nullness.compatqual.NullableDecl;
+import javax.annotation.CheckForNull;
+import org.checkerframework.checker.nullness.qual.Nullable;
 
 /** Implementations of {@code Futures.catching*}. */
 @GwtCompatible
-abstract class AbstractCatchingFuture<V, X extends Throwable, F, T>
+@ElementTypesAreNonnullByDefault
+@SuppressWarnings("nullness") // TODO(b/147136275): Remove once our checker understands & and |.
+abstract class AbstractCatchingFuture<
+        V extends @Nullable Object, X extends Throwable, F, T extends @Nullable Object>
     extends FluentFuture.TrustedFuture<V> implements Runnable {
-  static <V, X extends Throwable> ListenableFuture<V> create(
+  static <V extends @Nullable Object, X extends Throwable> ListenableFuture<V> create(
       ListenableFuture<? extends V> input,
       Class<X> exceptionType,
       Function<? super X, ? extends V> fallback,
@@ -42,7 +47,7 @@ static <V, X extends Throwable> ListenableFuture<V> create(
     return future;
   }
 
-  static <X extends Throwable, V> ListenableFuture<V> create(
+  static <X extends Throwable, V extends @Nullable Object> ListenableFuture<V> create(
       ListenableFuture<? extends V> input,
       Class<X> exceptionType,
       AsyncFunction<? super X, ? extends V> fallback,
@@ -56,9 +61,9 @@ static <X extends Throwable, V> ListenableFuture<V> create(
    * In certain circumstances, this field might theoretically not be visible to an afterDone() call
    * triggered by cancel(). For details, see the comments on the fields of TimeoutFuture.
    */
-  @NullableDecl ListenableFuture<? extends V> inputFuture;
-  @NullableDecl Class<X> exceptionType;
-  @NullableDecl F fallback;
+  @CheckForNull ListenableFuture<? extends V> inputFuture;
+  @CheckForNull Class<X> exceptionType;
+  @CheckForNull F fallback;
 
   AbstractCatchingFuture(
       ListenableFuture<? extends V> inputFuture, Class<X> exceptionType, F fallback) {
@@ -107,7 +112,11 @@ public final void run() {
     }
 
     if (throwable == null) {
-      set(sourceResult);
+      /*
+       * The cast is safe: There was no exception, so the assignment from getDone must have
+       * succeeded.
+       */
+      set(uncheckedCastNullableTToT(sourceResult));
       return;
     }
 
@@ -134,6 +143,7 @@ public final void run() {
   }
 
   @Override
+  @CheckForNull
   protected String pendingToString() {
     ListenableFuture<? extends V> localInputFuture = inputFuture;
     Class<X> localExceptionType = exceptionType;
@@ -158,12 +168,12 @@ protected String pendingToString() {
 
   /** Template method for subtypes to actually run the fallback. */
   @ForOverride
-  @NullableDecl
+  @ParametricNullness
   abstract T doFallback(F fallback, X throwable) throws Exception;
 
   /** Template method for subtypes to actually set the result. */
   @ForOverride
-  abstract void setResult(@NullableDecl T result);
+  abstract void setResult(@ParametricNullness T result);
 
   @Override
   protected final void afterDone() {
@@ -177,7 +187,7 @@ protected final void afterDone() {
    * An {@link AbstractCatchingFuture} that delegates to an {@link AsyncFunction} and {@link
    * #setFuture(ListenableFuture)}.
    */
-  private static final class AsyncCatchingFuture<V, X extends Throwable>
+  private static final class AsyncCatchingFuture<V extends @Nullable Object, X extends Throwable>
       extends AbstractCatchingFuture<
           V, X, AsyncFunction<? super X, ? extends V>, ListenableFuture<? extends V>> {
     AsyncCatchingFuture(
@@ -209,7 +219,7 @@ void setResult(ListenableFuture<? extends V> result) {
    * An {@link AbstractCatchingFuture} that delegates to a {@link Function} and {@link
    * #set(Object)}.
    */
-  private static final class CatchingFuture<V, X extends Throwable>
+  private static final class CatchingFuture<V extends @Nullable Object, X extends Throwable>
       extends AbstractCatchingFuture<V, X, Function<? super X, ? extends V>, V> {
     CatchingFuture(
         ListenableFuture<? extends V> input,
@@ -219,13 +229,13 @@ private static final class CatchingFuture<V, X extends Throwable>
     }
 
     @Override
-    @NullableDecl
+    @ParametricNullness
     V doFallback(Function<? super X, ? extends V> fallback, X cause) throws Exception {
       return fallback.apply(cause);
     }
 
     @Override
-    void setResult(@NullableDecl V result) {
+    void setResult(@ParametricNullness V result) {
       set(result);
     }
   }
diff --git a/android/guava/src/com/google/common/util/concurrent/AbstractExecutionThreadService.java b/android/guava/src/com/google/common/util/concurrent/AbstractExecutionThreadService.java
index 2bd392ca6df7..0dbafd3f8b89 100644
--- a/android/guava/src/com/google/common/util/concurrent/AbstractExecutionThreadService.java
+++ b/android/guava/src/com/google/common/util/concurrent/AbstractExecutionThreadService.java
@@ -33,6 +33,7 @@
  * @since 1.0
  */
 @GwtIncompatible
+@ElementTypesAreNonnullByDefault
 public abstract class AbstractExecutionThreadService implements Service {
   private static final Logger logger =
       Logger.getLogger(AbstractExecutionThreadService.class.getName());
diff --git a/android/guava/src/com/google/common/util/concurrent/AbstractFuture.java b/android/guava/src/com/google/common/util/concurrent/AbstractFuture.java
index e7992415c9c7..3e08045d9434 100644
--- a/android/guava/src/com/google/common/util/concurrent/AbstractFuture.java
+++ b/android/guava/src/com/google/common/util/concurrent/AbstractFuture.java
@@ -16,8 +16,10 @@
 
 import static com.google.common.base.Preconditions.checkNotNull;
 import static com.google.common.base.Throwables.throwIfUnchecked;
+import static com.google.common.util.concurrent.NullnessCasts.uncheckedNull;
 import static java.lang.Integer.toHexString;
 import static java.lang.System.identityHashCode;
+import static java.util.Objects.requireNonNull;
 import static java.util.concurrent.atomic.AtomicReferenceFieldUpdater.newUpdater;
 
 import com.google.common.annotations.Beta;
@@ -43,7 +45,8 @@
 import java.util.concurrent.locks.LockSupport;
 import java.util.logging.Level;
 import java.util.logging.Logger;
-import org.checkerframework.checker.nullness.compatqual.NullableDecl;
+import javax.annotation.CheckForNull;
+import org.checkerframework.checker.nullness.qual.Nullable;
 
 /**
  * An abstract implementation of {@link ListenableFuture}, intended for advanced users only. More
@@ -64,14 +67,18 @@
  * @author Luke Sandberg
  * @since 1.0
  */
-@SuppressWarnings("ShortCircuitBoolean") // we use non-short circuiting comparisons intentionally
+@SuppressWarnings({
+  "ShortCircuitBoolean", // we use non-short circuiting comparisons intentionally
+  "nullness", // TODO(b/147136275): Remove once our checker understands & and |.
+})
 @GwtCompatible(emulated = true)
 @ReflectionSupport(value = ReflectionSupport.Level.FULL)
-public abstract class AbstractFuture<V> extends InternalFutureFailureAccess
+@ElementTypesAreNonnullByDefault
+public abstract class AbstractFuture<V extends @Nullable Object> extends InternalFutureFailureAccess
     implements ListenableFuture<V> {
   // NOTE: Whenever both tests are cheap and functional, it's faster to use &, | instead of &&, ||
 
-  private static final boolean GENERATE_CANCELLATION_CAUSES;
+  static final boolean GENERATE_CANCELLATION_CAUSES;
 
   static {
     // System.getProperty may throw if the security policy does not permit access.
@@ -91,21 +98,24 @@ public abstract class AbstractFuture<V> extends InternalFutureFailureAccess
    * of this interface must also be an AbstractFuture and must not override or expose for overriding
    * any of the public methods of ListenableFuture.
    */
-  interface Trusted<V> extends ListenableFuture<V> {}
+  interface Trusted<V extends @Nullable Object> extends ListenableFuture<V> {}
 
   /**
    * A less abstract subclass of AbstractFuture. This can be used to optimize setFuture by ensuring
    * that {@link #get} calls exactly the implementation of {@link AbstractFuture#get}.
    */
-  abstract static class TrustedFuture<V> extends AbstractFuture<V> implements Trusted<V> {
+  abstract static class TrustedFuture<V extends @Nullable Object> extends AbstractFuture<V>
+      implements Trusted<V> {
     @CanIgnoreReturnValue
     @Override
+    @ParametricNullness
     public final V get() throws InterruptedException, ExecutionException {
       return super.get();
     }
 
     @CanIgnoreReturnValue
     @Override
+    @ParametricNullness
     public final V get(long timeout, TimeUnit unit)
         throws InterruptedException, ExecutionException, TimeoutException {
       return super.get(timeout, unit);
@@ -191,8 +201,8 @@ public final boolean cancel(boolean mayInterruptIfRunning) {
   private static final class Waiter {
     static final Waiter TOMBSTONE = new Waiter(false /* ignored param */);
 
-    @NullableDecl volatile Thread thread;
-    @NullableDecl volatile Waiter next;
+    @CheckForNull volatile Thread thread;
+    @CheckForNull volatile Waiter next;
 
     /**
      * Constructor for the TOMBSTONE, avoids use of ATOMIC_HELPER in case this class is loaded
@@ -207,7 +217,7 @@ private static final class Waiter {
 
     // non-volatile write to the next field. Should be made visible by subsequent CAS on waiters
     // field.
-    void setNext(Waiter next) {
+    void setNext(@CheckForNull Waiter next) {
       ATOMIC_HELPER.putNext(this, next);
     }
 
@@ -264,17 +274,24 @@ private void removeWaiter(Waiter node) {
 
   /** Listeners also form a stack through the {@link #listeners} field. */
   private static final class Listener {
-    static final Listener TOMBSTONE = new Listener(null, null);
+    static final Listener TOMBSTONE = new Listener();
+    @CheckForNull // null only for TOMBSTONE
     final Runnable task;
+    @CheckForNull // null only for TOMBSTONE
     final Executor executor;
 
     // writes to next are made visible by subsequent CAS's on the listeners field
-    @NullableDecl Listener next;
+    @CheckForNull Listener next;
 
     Listener(Runnable task, Executor executor) {
       this.task = task;
       this.executor = executor;
     }
+
+    Listener() {
+      this.task = null;
+      this.executor = null;
+    }
   }
 
   /** A special value to represent {@code null}. */
@@ -300,8 +317,8 @@ public synchronized Throwable fillInStackTrace() {
   /** A special value to represent cancellation and the 'wasInterrupted' bit. */
   private static final class Cancellation {
     // constants to use when GENERATE_CANCELLATION_CAUSES = false
-    static final Cancellation CAUSELESS_INTERRUPTED;
-    static final Cancellation CAUSELESS_CANCELLED;
+    @CheckForNull static final Cancellation CAUSELESS_INTERRUPTED;
+    @CheckForNull static final Cancellation CAUSELESS_CANCELLED;
 
     static {
       if (GENERATE_CANCELLATION_CAUSES) {
@@ -314,16 +331,16 @@ private static final class Cancellation {
     }
 
     final boolean wasInterrupted;
-    @NullableDecl final Throwable cause;
+    @CheckForNull final Throwable cause;
 
-    Cancellation(boolean wasInterrupted, @NullableDecl Throwable cause) {
+    Cancellation(boolean wasInterrupted, @CheckForNull Throwable cause) {
       this.wasInterrupted = wasInterrupted;
       this.cause = cause;
     }
   }
 
   /** A special value that encodes the 'setFuture' state. */
-  private static final class SetFuture<V> implements Runnable {
+  private static final class SetFuture<V extends @Nullable Object> implements Runnable {
     final AbstractFuture<V> owner;
     final ListenableFuture<? extends V> future;
 
@@ -362,13 +379,13 @@ public void run() {
    *       argument.
    * </ul>
    */
-  @NullableDecl private volatile Object value;
+  @CheckForNull private volatile Object value;
 
   /** All listeners. */
-  @NullableDecl private volatile Listener listeners;
+  @CheckForNull private volatile Listener listeners;
 
   /** All waiting threads. */
-  @NullableDecl private volatile Waiter waiters;
+  @CheckForNull private volatile Waiter waiters;
 
   /** Constructor for use by subclasses. */
   protected AbstractFuture() {}
@@ -407,6 +424,7 @@ protected AbstractFuture() {}
    */
   @CanIgnoreReturnValue
   @Override
+  @ParametricNullness
   public V get(long timeout, TimeUnit unit)
       throws InterruptedException, TimeoutException, ExecutionException {
     // NOTE: if timeout < 0, remainingNanos will be < 0 and we will fall into the while(true) loop
@@ -459,7 +477,8 @@ public V get(long timeout, TimeUnit unit)
       }
       // re-read value, if we get here then we must have observed a TOMBSTONE while trying to add a
       // waiter.
-      return getDoneValue(value);
+      // requireNonNull is safe because value is always set before TOMBSTONE.
+      return getDoneValue(requireNonNull(value));
     }
     // If we get here then we have remainingNanos < SPIN_THRESHOLD_NANOS and there is no node on the
     // waiters list
@@ -518,6 +537,7 @@ public V get(long timeout, TimeUnit unit)
    */
   @CanIgnoreReturnValue
   @Override
+  @ParametricNullness
   public V get() throws InterruptedException, ExecutionException {
     if (Thread.interrupted()) {
       throw new InterruptedException();
@@ -553,10 +573,12 @@ public V get() throws InterruptedException, ExecutionException {
     }
     // re-read value, if we get here then we must have observed a TOMBSTONE while trying to add a
     // waiter.
-    return getDoneValue(value);
+    // requireNonNull is safe because value is always set before TOMBSTONE.
+    return getDoneValue(requireNonNull(value));
   }
 
   /** Unboxes {@code obj}. Assumes that obj is not {@code null} or a {@link SetFuture}. */
+  @ParametricNullness
   private V getDoneValue(Object obj) throws ExecutionException {
     // While this seems like it might be too branch-y, simple benchmarking proves it to be
     // unmeasurable (comparing done AbstractFutures with immediateFuture)
@@ -565,7 +587,11 @@ private V getDoneValue(Object obj) throws ExecutionException {
     } else if (obj instanceof Failure) {
       throw new ExecutionException(((Failure) obj).exception);
     } else if (obj == NULL) {
-      return null;
+      /*
+       * It's safe to return null because we would only have stored it in the first place if it were
+       * a valid value for V.
+       */
+      return uncheckedNull();
     } else {
       @SuppressWarnings("unchecked") // this is the only other option
       V asV = (V) obj;
@@ -613,9 +639,20 @@ public boolean cancel(boolean mayInterruptIfRunning) {
           GENERATE_CANCELLATION_CAUSES
               ? new Cancellation(
                   mayInterruptIfRunning, new CancellationException("Future.cancel() was called."))
-              : (mayInterruptIfRunning
-                  ? Cancellation.CAUSELESS_INTERRUPTED
-                  : Cancellation.CAUSELESS_CANCELLED);
+              /*
+               * requireNonNull is safe because we've initialized these if
+               * !GENERATE_CANCELLATION_CAUSES.
+               *
+               * TODO(cpovirk): Maybe it would be cleaner to define a CancellationSupplier interface
+               * with two implementations, one that contains causeless Cancellation instances and
+               * the other of which creates new Cancellation instances each time it's called? Yet
+               * another alternative is to fill in a non-null value for each of the fields no matter
+               * what and to just not use it if !GENERATE_CANCELLATION_CAUSES.
+               */
+              : requireNonNull(
+                  mayInterruptIfRunning
+                      ? Cancellation.CAUSELESS_INTERRUPTED
+                      : Cancellation.CAUSELESS_CANCELLED);
       AbstractFuture<?> abstractFuture = this;
       while (true) {
         if (ATOMIC_HELPER.casValue(abstractFuture, localValue, valueToSet)) {
@@ -740,7 +777,7 @@ public void addListener(Runnable listener, Executor executor) {
    * @return true if the attempt was accepted, completing the {@code Future}
    */
   @CanIgnoreReturnValue
-  protected boolean set(@NullableDecl V value) {
+  protected boolean set(@ParametricNullness V value) {
     Object valueToSet = value == null ? NULL : value;
     if (ATOMIC_HELPER.casValue(this, null, valueToSet)) {
       complete(this);
@@ -816,7 +853,7 @@ protected boolean setFuture(ListenableFuture<? extends V> future) {
         }
         return false;
       }
-      SetFuture valueToSet = new SetFuture<V>(this, future);
+      SetFuture<V> valueToSet = new SetFuture<V>(this, future);
       if (ATOMIC_HELPER.casValue(this, null, valueToSet)) {
         // the listener is responsible for calling completeWithFuture, directExecutor is appropriate
         // since all we are doing is unpacking a completed future which should be fast.
@@ -873,7 +910,8 @@ private static Object getFutureValue(ListenableFuture<?> future) {
                   : Cancellation.CAUSELESS_CANCELLED;
         }
       }
-      return v;
+      // requireNonNull is safe as long as we call this method only on completed futures.
+      return requireNonNull(v);
     }
     if (future instanceof InternalFutureFailureAccess) {
       Throwable throwable =
@@ -885,7 +923,11 @@ private static Object getFutureValue(ListenableFuture<?> future) {
     boolean wasCancelled = future.isCancelled();
     // Don't allocate a CancellationException if it's not necessary
     if (!GENERATE_CANCELLATION_CAUSES & wasCancelled) {
-      return Cancellation.CAUSELESS_CANCELLED;
+      /*
+       * requireNonNull is safe because we've initialized CAUSELESS_CANCELLED if
+       * !GENERATE_CANCELLATION_CAUSES.
+       */
+      return requireNonNull(Cancellation.CAUSELESS_CANCELLED);
     }
     // Otherwise calculate the value by calling .get()
     try {
@@ -928,7 +970,9 @@ private static Object getFutureValue(ListenableFuture<?> future) {
    * An inlined private copy of {@link Uninterruptibles#getUninterruptibly} used to break an
    * internal dependency on other /util/concurrent classes.
    */
-  private static <V> V getUninterruptibly(Future<V> future) throws ExecutionException {
+  @ParametricNullness
+  private static <V extends @Nullable Object> V getUninterruptibly(Future<V> future)
+      throws ExecutionException {
     boolean interrupted = false;
     try {
       while (true) {
@@ -946,7 +990,10 @@ private static <V> V getUninterruptibly(Future<V> future) throws ExecutionExcept
   }
 
   /** Unblocks all threads and runs all listeners. */
-  private static void complete(AbstractFuture<?> future) {
+  private static void complete(AbstractFuture<?> param) {
+    // Declare a "true" local variable so that the Checker Framework will infer nullness.
+    AbstractFuture<?> future = param;
+
     Listener next = null;
     outer:
     while (true) {
@@ -963,7 +1010,11 @@ private static void complete(AbstractFuture<?> future) {
       while (next != null) {
         Listener curr = next;
         next = next.next;
-        Runnable task = curr.task;
+        /*
+         * requireNonNull is safe because the listener stack never contains TOMBSTONE until after
+         * clearListeners.
+         */
+        Runnable task = requireNonNull(curr.task);
         if (task instanceof SetFuture) {
           SetFuture<?> setFuture = (SetFuture<?>) task;
           // We unwind setFuture specifically to avoid StackOverflowErrors in the case of long
@@ -980,7 +1031,11 @@ private static void complete(AbstractFuture<?> future) {
           }
           // other wise the future we were trying to set is already done.
         } else {
-          executeListener(task, curr.executor);
+          /*
+           * requireNonNull is safe because the listener stack never contains TOMBSTONE until after
+           * clearListeners.
+           */
+          executeListener(task, requireNonNull(curr.executor));
         }
       }
       break;
@@ -1024,7 +1079,12 @@ protected void afterDone() {}
    * @since 27.0
    */
   @Override
-  @NullableDecl
+  /*
+   * We should annotate the superclass, InternalFutureFailureAccess, to say that its copy of this
+   * method returns @Nullable, too. However, we're not sure if we want to make any changes to that
+   * class, since it's in a separate artifact that we planned to release only a single version of.
+   */
+  @CheckForNull
   protected final Throwable tryInternalFastPathGetFailure() {
     if (this instanceof Trusted) {
       Object obj = value;
@@ -1039,7 +1099,7 @@ protected final Throwable tryInternalFastPathGetFailure() {
    * If this future has been cancelled (and possibly interrupted), cancels (and possibly interrupts)
    * the given future (if available).
    */
-  final void maybePropagateCancellationTo(@NullableDecl Future<?> related) {
+  final void maybePropagateCancellationTo(@CheckForNull Future<?> related) {
     if (related != null & isCancelled()) {
       related.cancel(wasInterrupted());
     }
@@ -1047,10 +1107,7 @@ final void maybePropagateCancellationTo(@NullableDecl Future<?> related) {
 
   /** Releases all threads in the {@link #waiters} list, and clears the list. */
   private void releaseWaiters() {
-    Waiter head;
-    do {
-      head = waiters;
-    } while (!ATOMIC_HELPER.casWaiters(this, head, Waiter.TOMBSTONE));
+    Waiter head = ATOMIC_HELPER.gasWaiters(this, Waiter.TOMBSTONE);
     for (Waiter currentWaiter = head; currentWaiter != null; currentWaiter = currentWaiter.next) {
       currentWaiter.unpark();
     }
@@ -1060,17 +1117,15 @@ private void releaseWaiters() {
    * Clears the {@link #listeners} list and prepends its contents to {@code onto}, least recently
    * added first.
    */
-  private Listener clearListeners(Listener onto) {
+  @CheckForNull
+  private Listener clearListeners(@CheckForNull Listener onto) {
     // We need to
     // 1. atomically swap the listeners with TOMBSTONE, this is because addListener uses that to
     //    to synchronize with us
     // 2. reverse the linked list, because despite our rather clear contract, people depend on us
     //    executing listeners in the order they were added
     // 3. push all the items onto 'onto' and return the new head of the stack
-    Listener head;
-    do {
-      head = listeners;
-    } while (!ATOMIC_HELPER.casListeners(this, head, Listener.TOMBSTONE));
+    Listener head = ATOMIC_HELPER.gasListeners(this, Listener.TOMBSTONE);
     Listener reversedList = onto;
     while (head != null) {
       Listener tmp = head;
@@ -1108,7 +1163,7 @@ public String toString() {
    * @return null if an explanation cannot be provided (e.g. because the future is done).
    * @since 23.0
    */
-  @NullableDecl
+  @CheckForNull
   protected String pendingToString() {
     // TODO(diamondm) consider moving this into addPendingString so it's always in the output
     if (this instanceof ScheduledFuture) {
@@ -1174,7 +1229,7 @@ private void addDoneString(StringBuilder builder) {
    * implementation. Using a reconstruction of the default Object.toString() prevents OOMs and stack
    * overflows, and helps avoid sensitive data inadvertently ending up in exception messages.
    */
-  private void appendResultObject(StringBuilder builder, Object o) {
+  private void appendResultObject(StringBuilder builder, @CheckForNull Object o) {
     if (o == null) {
       builder.append("null");
     } else if (o == this) {
@@ -1188,7 +1243,7 @@ private void appendResultObject(StringBuilder builder, Object o) {
   }
 
   /** Helper for printing user supplied objects into our toString method. */
-  private void appendUserObject(StringBuilder builder, Object o) {
+  private void appendUserObject(StringBuilder builder, @CheckForNull Object o) {
     // This is some basic recursion detection for when people create cycles via set/setFuture or
     // when deep chains of futures exist resulting in a StackOverflowException. We could detect
     // arbitrary cycles using a thread local but this should be a good enough solution (it is also
@@ -1229,16 +1284,24 @@ private abstract static class AtomicHelper {
     abstract void putThread(Waiter waiter, Thread newValue);
 
     /** Non volatile write of the waiter to the {@link Waiter#next} field. */
-    abstract void putNext(Waiter waiter, Waiter newValue);
+    abstract void putNext(Waiter waiter, @CheckForNull Waiter newValue);
 
     /** Performs a CAS operation on the {@link #waiters} field. */
-    abstract boolean casWaiters(AbstractFuture<?> future, Waiter expect, Waiter update);
+    abstract boolean casWaiters(
+        AbstractFuture<?> future, @CheckForNull Waiter expect, @CheckForNull Waiter update);
 
     /** Performs a CAS operation on the {@link #listeners} field. */
-    abstract boolean casListeners(AbstractFuture<?> future, Listener expect, Listener update);
+    abstract boolean casListeners(
+        AbstractFuture<?> future, @CheckForNull Listener expect, Listener update);
+
+    /** Performs a GAS operation on the {@link #waiters} field. */
+    abstract Waiter gasWaiters(AbstractFuture<?> future, Waiter update);
+
+    /** Performs a GAS operation on the {@link #listeners} field. */
+    abstract Listener gasListeners(AbstractFuture<?> future, Listener update);
 
     /** Performs a CAS operation on the {@link #value} field. */
-    abstract boolean casValue(AbstractFuture<?> future, Object expect, Object update);
+    abstract boolean casValue(AbstractFuture<?> future, @CheckForNull Object expect, Object update);
   }
 
   /**
@@ -1247,6 +1310,7 @@ private abstract static class AtomicHelper {
    * <p>Static initialization of this class will fail if the {@link sun.misc.Unsafe} object cannot
    * be accessed.
    */
+  @SuppressWarnings("sunapi")
   private static final class UnsafeAtomicHelper extends AtomicHelper {
     static final sun.misc.Unsafe UNSAFE;
     static final long LISTENERS_OFFSET;
@@ -1301,30 +1365,60 @@ void putThread(Waiter waiter, Thread newValue) {
     }
 
     @Override
-    void putNext(Waiter waiter, Waiter newValue) {
+    void putNext(Waiter waiter, @CheckForNull Waiter newValue) {
       UNSAFE.putObject(waiter, WAITER_NEXT_OFFSET, newValue);
     }
 
     /** Performs a CAS operation on the {@link #waiters} field. */
     @Override
-    boolean casWaiters(AbstractFuture<?> future, Waiter expect, Waiter update) {
+    boolean casWaiters(
+        AbstractFuture<?> future, @CheckForNull Waiter expect, @CheckForNull Waiter update) {
       return UNSAFE.compareAndSwapObject(future, WAITERS_OFFSET, expect, update);
     }
 
     /** Performs a CAS operation on the {@link #listeners} field. */
     @Override
-    boolean casListeners(AbstractFuture<?> future, Listener expect, Listener update) {
+    boolean casListeners(AbstractFuture<?> future, @CheckForNull Listener expect, Listener update) {
       return UNSAFE.compareAndSwapObject(future, LISTENERS_OFFSET, expect, update);
     }
 
+    /** Performs a GAS operation on the {@link #listeners} field. */
+    @Override
+    Listener gasListeners(AbstractFuture<?> future, Listener update) {
+      while (true) {
+        Listener listener = future.listeners;
+        if (update == listener) {
+          return listener;
+        }
+        if (casListeners(future, listener, update)) {
+          return listener;
+        }
+      }
+    }
+
+    /** Performs a GAS operation on the {@link #waiters} field. */
+    @Override
+    Waiter gasWaiters(AbstractFuture<?> future, Waiter update) {
+      while (true) {
+        Waiter waiter = future.waiters;
+        if (update == waiter) {
+          return waiter;
+        }
+        if (casWaiters(future, waiter, update)) {
+          return waiter;
+        }
+      }
+    }
+
     /** Performs a CAS operation on the {@link #value} field. */
     @Override
-    boolean casValue(AbstractFuture<?> future, Object expect, Object update) {
+    boolean casValue(AbstractFuture<?> future, @CheckForNull Object expect, Object update) {
       return UNSAFE.compareAndSwapObject(future, VALUE_OFFSET, expect, update);
     }
   }
 
   /** {@link AtomicHelper} based on {@link AtomicReferenceFieldUpdater}. */
+  @SuppressWarnings("rawtypes")
   private static final class SafeAtomicHelper extends AtomicHelper {
     final AtomicReferenceFieldUpdater<Waiter, Thread> waiterThreadUpdater;
     final AtomicReferenceFieldUpdater<Waiter, Waiter> waiterNextUpdater;
@@ -1351,22 +1445,35 @@ void putThread(Waiter waiter, Thread newValue) {
     }
 
     @Override
-    void putNext(Waiter waiter, Waiter newValue) {
+    void putNext(Waiter waiter, @CheckForNull Waiter newValue) {
       waiterNextUpdater.lazySet(waiter, newValue);
     }
 
     @Override
-    boolean casWaiters(AbstractFuture<?> future, Waiter expect, Waiter update) {
+    boolean casWaiters(
+        AbstractFuture<?> future, @CheckForNull Waiter expect, @CheckForNull Waiter update) {
       return waitersUpdater.compareAndSet(future, expect, update);
     }
 
     @Override
-    boolean casListeners(AbstractFuture<?> future, Listener expect, Listener update) {
+    boolean casListeners(AbstractFuture<?> future, @CheckForNull Listener expect, Listener update) {
       return listenersUpdater.compareAndSet(future, expect, update);
     }
 
+    /** Performs a GAS operation on the {@link #listeners} field. */
     @Override
-    boolean casValue(AbstractFuture<?> future, Object expect, Object update) {
+    Listener gasListeners(AbstractFuture<?> future, Listener update) {
+      return listenersUpdater.getAndSet(future, update);
+    }
+
+    /** Performs a GAS operation on the {@link #waiters} field. */
+    @Override
+    Waiter gasWaiters(AbstractFuture<?> future, Waiter update) {
+      return waitersUpdater.getAndSet(future, update);
+    }
+
+    @Override
+    boolean casValue(AbstractFuture<?> future, @CheckForNull Object expect, Object update) {
       return valueUpdater.compareAndSet(future, expect, update);
     }
   }
@@ -1384,12 +1491,13 @@ void putThread(Waiter waiter, Thread newValue) {
     }
 
     @Override
-    void putNext(Waiter waiter, Waiter newValue) {
+    void putNext(Waiter waiter, @CheckForNull Waiter newValue) {
       waiter.next = newValue;
     }
 
     @Override
-    boolean casWaiters(AbstractFuture<?> future, Waiter expect, Waiter update) {
+    boolean casWaiters(
+        AbstractFuture<?> future, @CheckForNull Waiter expect, @CheckForNull Waiter update) {
       synchronized (future) {
         if (future.waiters == expect) {
           future.waiters = update;
@@ -1400,7 +1508,7 @@ boolean casWaiters(AbstractFuture<?> future, Waiter expect, Waiter update) {
     }
 
     @Override
-    boolean casListeners(AbstractFuture<?> future, Listener expect, Listener update) {
+    boolean casListeners(AbstractFuture<?> future, @CheckForNull Listener expect, Listener update) {
       synchronized (future) {
         if (future.listeners == expect) {
           future.listeners = update;
@@ -1410,8 +1518,32 @@ boolean casListeners(AbstractFuture<?> future, Listener expect, Listener update)
       }
     }
 
+    /** Performs a GAS operation on the {@link #listeners} field. */
+    @Override
+    Listener gasListeners(AbstractFuture<?> future, Listener update) {
+      synchronized (future) {
+        Listener old = future.listeners;
+        if (old != update) {
+          future.listeners = update;
+        }
+        return old;
+      }
+    }
+
+    /** Performs a GAS operation on the {@link #waiters} field. */
+    @Override
+    Waiter gasWaiters(AbstractFuture<?> future, Waiter update) {
+      synchronized (future) {
+        Waiter old = future.waiters;
+        if (old != update) {
+          future.waiters = update;
+        }
+        return old;
+      }
+    }
+
     @Override
-    boolean casValue(AbstractFuture<?> future, Object expect, Object update) {
+    boolean casValue(AbstractFuture<?> future, @CheckForNull Object expect, Object update) {
       synchronized (future) {
         if (future.value == expect) {
           future.value = update;
@@ -1423,7 +1555,7 @@ boolean casValue(AbstractFuture<?> future, Object expect, Object update) {
   }
 
   private static CancellationException cancellationExceptionWithCause(
-      @NullableDecl String message, @NullableDecl Throwable cause) {
+      String message, @CheckForNull Throwable cause) {
     CancellationException exception = new CancellationException(message);
     exception.initCause(cause);
     return exception;
diff --git a/android/guava/src/com/google/common/util/concurrent/AbstractIdleService.java b/android/guava/src/com/google/common/util/concurrent/AbstractIdleService.java
index 7416a9b655b2..05bc4b9a7cf3 100644
--- a/android/guava/src/com/google/common/util/concurrent/AbstractIdleService.java
+++ b/android/guava/src/com/google/common/util/concurrent/AbstractIdleService.java
@@ -31,6 +31,7 @@
  * @since 1.0
  */
 @GwtIncompatible
+@ElementTypesAreNonnullByDefault
 public abstract class AbstractIdleService implements Service {
 
   /* Thread names will look like {@code "MyService STARTING"}. */
diff --git a/android/guava/src/com/google/common/util/concurrent/AbstractListeningExecutorService.java b/android/guava/src/com/google/common/util/concurrent/AbstractListeningExecutorService.java
index 22157bab2371..fd5c5c911533 100644
--- a/android/guava/src/com/google/common/util/concurrent/AbstractListeningExecutorService.java
+++ b/android/guava/src/com/google/common/util/concurrent/AbstractListeningExecutorService.java
@@ -20,7 +20,7 @@
 import java.util.concurrent.AbstractExecutorService;
 import java.util.concurrent.Callable;
 import java.util.concurrent.RunnableFuture;
-import org.checkerframework.checker.nullness.compatqual.NullableDecl;
+import org.checkerframework.checker.nullness.qual.Nullable;
 
 /**
  * Abstract {@link ListeningExecutorService} implementation that creates {@link ListenableFuture}
@@ -36,18 +36,20 @@
 @Beta
 @CanIgnoreReturnValue
 @GwtIncompatible
+@ElementTypesAreNonnullByDefault
 public abstract class AbstractListeningExecutorService extends AbstractExecutorService
     implements ListeningExecutorService {
 
   /** @since 19.0 (present with return type {@code ListenableFutureTask} since 14.0) */
   @Override
-  protected final <T> RunnableFuture<T> newTaskFor(Runnable runnable, T value) {
+  protected final <T extends @Nullable Object> RunnableFuture<T> newTaskFor(
+      Runnable runnable, @ParametricNullness T value) {
     return TrustedListenableFutureTask.create(runnable, value);
   }
 
   /** @since 19.0 (present with return type {@code ListenableFutureTask} since 14.0) */
   @Override
-  protected final <T> RunnableFuture<T> newTaskFor(Callable<T> callable) {
+  protected final <T extends @Nullable Object> RunnableFuture<T> newTaskFor(Callable<T> callable) {
     return TrustedListenableFutureTask.create(callable);
   }
 
@@ -57,12 +59,13 @@ public ListenableFuture<?> submit(Runnable task) {
   }
 
   @Override
-  public <T> ListenableFuture<T> submit(Runnable task, @NullableDecl T result) {
+  public <T extends @Nullable Object> ListenableFuture<T> submit(
+      Runnable task, @ParametricNullness T result) {
     return (ListenableFuture<T>) super.submit(task, result);
   }
 
   @Override
-  public <T> ListenableFuture<T> submit(Callable<T> task) {
+  public <T extends @Nullable Object> ListenableFuture<T> submit(Callable<T> task) {
     return (ListenableFuture<T>) super.submit(task);
   }
 }
diff --git a/android/guava/src/com/google/common/util/concurrent/AbstractScheduledService.java b/android/guava/src/com/google/common/util/concurrent/AbstractScheduledService.java
index 70d4fb759aac..7288ba53d728 100644
--- a/android/guava/src/com/google/common/util/concurrent/AbstractScheduledService.java
+++ b/android/guava/src/com/google/common/util/concurrent/AbstractScheduledService.java
@@ -16,7 +16,9 @@
 
 import static com.google.common.base.Preconditions.checkArgument;
 import static com.google.common.base.Preconditions.checkNotNull;
+import static com.google.common.util.concurrent.Futures.immediateCancelledFuture;
 import static com.google.common.util.concurrent.MoreExecutors.directExecutor;
+import static java.util.Objects.requireNonNull;
 
 import com.google.common.annotations.GwtIncompatible;
 import com.google.common.base.Supplier;
@@ -28,13 +30,15 @@
 import java.util.concurrent.Executors;
 import java.util.concurrent.Future;
 import java.util.concurrent.ScheduledExecutorService;
+import java.util.concurrent.ScheduledFuture;
 import java.util.concurrent.ThreadFactory;
 import java.util.concurrent.TimeUnit;
 import java.util.concurrent.TimeoutException;
 import java.util.concurrent.locks.ReentrantLock;
 import java.util.logging.Level;
 import java.util.logging.Logger;
-import org.checkerframework.checker.nullness.compatqual.NullableDecl;
+import javax.annotation.CheckForNull;
+import org.checkerframework.checker.nullness.qual.Nullable;
 
 /**
  * Base class for services that can implement {@link #startUp} and {@link #shutDown} but while in
@@ -94,6 +98,7 @@
  * @since 11.0
  */
 @GwtIncompatible
+@ElementTypesAreNonnullByDefault
 public abstract class AbstractScheduledService implements Service {
   private static final Logger logger = Logger.getLogger(AbstractScheduledService.class.getName());
 
@@ -126,9 +131,10 @@ public static Scheduler newFixedDelaySchedule(
       checkArgument(delay > 0, "delay must be > 0, found %s", delay);
       return new Scheduler() {
         @Override
-        public Future<?> schedule(
+        public Cancellable schedule(
             AbstractService service, ScheduledExecutorService executor, Runnable task) {
-          return executor.scheduleWithFixedDelay(task, initialDelay, delay, unit);
+          return new FutureAsCancellable(
+              executor.scheduleWithFixedDelay(task, initialDelay, delay, unit));
         }
       };
     }
@@ -148,15 +154,16 @@ public static Scheduler newFixedRateSchedule(
       checkArgument(period > 0, "period must be > 0, found %s", period);
       return new Scheduler() {
         @Override
-        public Future<?> schedule(
+        public Cancellable schedule(
             AbstractService service, ScheduledExecutorService executor, Runnable task) {
-          return executor.scheduleAtFixedRate(task, initialDelay, period, unit);
+          return new FutureAsCancellable(
+              executor.scheduleAtFixedRate(task, initialDelay, period, unit));
         }
       };
     }
 
     /** Schedules the task to run on the provided executor on behalf of the service. */
-    abstract Future<?> schedule(
+    abstract Cancellable schedule(
         AbstractService service, ScheduledExecutorService executor, Runnable runnable);
 
     private Scheduler() {}
@@ -170,8 +177,8 @@ private final class ServiceDelegate extends AbstractService {
 
     // A handle to the running task so that we can stop it when a shutdown has been requested.
     // These two fields are volatile because their values will be accessed from multiple threads.
-    @NullableDecl private volatile Future<?> runningTask;
-    @NullableDecl private volatile ScheduledExecutorService executorService;
+    @CheckForNull private volatile Cancellable runningTask;
+    @CheckForNull private volatile ScheduledExecutorService executorService;
 
     // This lock protects the task so we can ensure that none of the template methods (startUp,
     // shutDown or runOneIteration) run concurrently with one another.
@@ -185,7 +192,11 @@ class Task implements Runnable {
       public void run() {
         lock.lock();
         try {
-          if (runningTask.isCancelled()) {
+          /*
+           * requireNonNull is safe because Task isn't run (or at least it doesn't succeed in taking
+           * the lock) until after it's scheduled and the runningTask field is set.
+           */
+          if (requireNonNull(runningTask).isCancelled()) {
             // task may have been cancelled while blocked on the lock.
             return;
           }
@@ -200,7 +211,8 @@ public void run() {
                 ignored);
           }
           notifyFailed(t);
-          runningTask.cancel(false); // prevent future invocations.
+          // requireNonNull is safe now, just as it was above.
+          requireNonNull(runningTask).cancel(false); // prevent future invocations.
         } finally {
           lock.unlock();
         }
@@ -244,6 +256,9 @@ public void run() {
 
     @Override
     protected final void doStop() {
+      // Both requireNonNull calls are safe because doStop can run only after a successful doStart.
+      requireNonNull(runningTask);
+      requireNonNull(executorService);
       runningTask.cancel(false);
       executorService.execute(
           new Runnable() {
@@ -316,9 +331,9 @@ protected void shutDown() throws Exception {}
    * fails}. Subclasses may override this method to supply a custom {@link ScheduledExecutorService}
    * instance. This method is guaranteed to only be called once.
    *
-   * <p>By default this returns a new {@link ScheduledExecutorService} with a single thread thread
-   * pool that sets the name of the thread to the {@linkplain #serviceName() service name}. Also,
-   * the pool will be {@linkplain ScheduledExecutorService#shutdown() shut down} when the service
+   * <p>By default this returns a new {@link ScheduledExecutorService} with a single thread pool
+   * that sets the name of the thread to the {@linkplain #serviceName() service name}. Also, the
+   * pool will be {@linkplain ScheduledExecutorService#shutdown() shut down} when the service
    * {@linkplain Service.State#TERMINATED terminates} or {@linkplain Service.State#TERMINATED
    * fails}.
    */
@@ -430,6 +445,30 @@ public final void awaitTerminated(long timeout, TimeUnit unit) throws TimeoutExc
     delegate.awaitTerminated(timeout, unit);
   }
 
+  interface Cancellable {
+    void cancel(boolean mayInterruptIfRunning);
+
+    boolean isCancelled();
+  }
+
+  private static final class FutureAsCancellable implements Cancellable {
+    private final Future<?> delegate;
+
+    FutureAsCancellable(Future<?> delegate) {
+      this.delegate = delegate;
+    }
+
+    @Override
+    public void cancel(boolean mayInterruptIfRunning) {
+      delegate.cancel(mayInterruptIfRunning);
+    }
+
+    @Override
+    public boolean isCancelled() {
+      return delegate.isCancelled();
+    }
+  }
+
   /**
    * A {@link Scheduler} that provides a convenient way for the {@link AbstractScheduledService} to
    * use a dynamically changing schedule. After every execution of the task, assuming it hasn't been
@@ -441,7 +480,7 @@ public final void awaitTerminated(long timeout, TimeUnit unit) throws TimeoutExc
   public abstract static class CustomScheduler extends Scheduler {
 
     /** A callable class that can reschedule itself using a {@link CustomScheduler}. */
-    private class ReschedulableCallable extends ForwardingFuture<Void> implements Callable<Void> {
+    private final class ReschedulableCallable implements Callable<@Nullable Void> {
 
       /** The underlying task. */
       private final Runnable wrappedRunnable;
@@ -453,6 +492,27 @@ private class ReschedulableCallable extends ForwardingFuture<Void> implements Ca
        * The service that is managing this callable. This is used so that failure can be reported
        * properly.
        */
+      /*
+       * This reference is part of a reference cycle, which is typically something we want to avoid
+       * under j2objc -- but it is not detected by our j2objc cycle test. The cycle:
+       *
+       * - CustomScheduler.service contains an instance of ServiceDelegate. (It needs it so that it
+       *   can call notifyFailed.)
+       *
+       * - ServiceDelegate.runningTask contains an instance of ReschedulableCallable (at least in
+       *   the case that the service is using CustomScheduler). (It needs it so that it can cancel
+       *   the task and detect whether it has been cancelled.)
+       *
+       * - ReschedulableCallable has a reference back to its enclosing CustomScheduler. (It needs it
+       *   so that it can call getNextSchedule).
+       *
+       * Maybe there is a way to avoid this cycle. But we think the cycle is safe enough to ignore:
+       * Each task is retained for only as long as it is running -- so it's retained only as long as
+       * it would already be retained by the underlying executor.
+       *
+       * If the cycle test starts reporting this cycle in the future, we should add an entry to
+       * cycle_suppress_list.txt.
+       */
       private final AbstractService service;
 
       /**
@@ -464,8 +524,8 @@ private class ReschedulableCallable extends ForwardingFuture<Void> implements Ca
 
       /** The future that represents the next execution of this task. */
       @GuardedBy("lock")
-      @NullableDecl
-      private Future<Void> currentFuture;
+      @CheckForNull
+      private SupplantableFuture cancellationDelegate;
 
       ReschedulableCallable(
           AbstractService service, ScheduledExecutorService executor, Runnable runnable) {
@@ -475,32 +535,36 @@ private class ReschedulableCallable extends ForwardingFuture<Void> implements Ca
       }
 
       @Override
+      @CheckForNull
       public Void call() throws Exception {
         wrappedRunnable.run();
         reschedule();
         return null;
       }
 
-      /** Atomically reschedules this task and assigns the new future to {@link #currentFuture}. */
-      public void reschedule() {
+      /**
+       * Atomically reschedules this task and assigns the new future to {@link
+       * #cancellationDelegate}.
+       */
+      @CanIgnoreReturnValue
+      public Cancellable reschedule() {
         // invoke the callback outside the lock, prevents some shenanigans.
         Schedule schedule;
         try {
           schedule = CustomScheduler.this.getNextSchedule();
         } catch (Throwable t) {
           service.notifyFailed(t);
-          return;
+          return new FutureAsCancellable(immediateCancelledFuture());
         }
         // We reschedule ourselves with a lock held for two reasons. 1. we want to make sure that
         // cancel calls cancel on the correct future. 2. we want to make sure that the assignment
         // to currentFuture doesn't race with itself so that currentFuture is assigned in the
         // correct order.
         Throwable scheduleFailure = null;
+        Cancellable toReturn;
         lock.lock();
         try {
-          if (currentFuture == null || !currentFuture.isCancelled()) {
-            currentFuture = executor.schedule(this, schedule.delay, schedule.unit);
-          }
+          toReturn = initializeOrUpdateCancellationDelegate(schedule);
         } catch (Throwable e) {
           // If an exception is thrown by the subclass then we need to make sure that the service
           // notices and transitions to the FAILED state. We do it by calling notifyFailed directly
@@ -511,6 +575,7 @@ public void reschedule() {
           // the AbstractService could monitor the future directly. Rescheduling is still hard...
           // but it would help with some of these lock ordering issues.
           scheduleFailure = e;
+          toReturn = new FutureAsCancellable(immediateCancelledFuture());
         } finally {
           lock.unlock();
         }
@@ -518,16 +583,63 @@ public void reschedule() {
         if (scheduleFailure != null) {
           service.notifyFailed(scheduleFailure);
         }
+        return toReturn;
+      }
+
+      @GuardedBy("lock")
+      /*
+       * The GuardedBy checker warns us that we're not holding cancellationDelegate.lock. But in
+       * fact we are holding it because it is the same as this.lock, which we know we are holding,
+       * thanks to @GuardedBy above. (cancellationDelegate.lock is initialized to this.lock in the
+       * call to `new SupplantableFuture` below.)
+       */
+      @SuppressWarnings("GuardedBy")
+      private Cancellable initializeOrUpdateCancellationDelegate(Schedule schedule) {
+        if (cancellationDelegate == null) {
+          return cancellationDelegate = new SupplantableFuture(lock, submitToExecutor(schedule));
+        }
+        if (!cancellationDelegate.currentFuture.isCancelled()) {
+          cancellationDelegate.currentFuture = submitToExecutor(schedule);
+        }
+        return cancellationDelegate;
+      }
+
+      private ScheduledFuture<@Nullable Void> submitToExecutor(Schedule schedule) {
+        return executor.schedule(this, schedule.delay, schedule.unit);
+      }
+    }
+
+    /**
+     * Contains the most recently submitted {@code Future}, which may be cancelled or updated,
+     * always under a lock.
+     */
+    private static final class SupplantableFuture implements Cancellable {
+      private final ReentrantLock lock;
+
+      @GuardedBy("lock")
+      private Future<@Nullable Void> currentFuture;
+
+      SupplantableFuture(ReentrantLock lock, Future<@Nullable Void> currentFuture) {
+        this.lock = lock;
+        this.currentFuture = currentFuture;
       }
 
-      // N.B. Only protect cancel and isCancelled because those are the only methods that are
-      // invoked by the AbstractScheduledService.
       @Override
-      public boolean cancel(boolean mayInterruptIfRunning) {
-        // Ensure that a task cannot be rescheduled while a cancel is ongoing.
+      public void cancel(boolean mayInterruptIfRunning) {
+        /*
+         * Lock to ensure that a task cannot be rescheduled while a cancel is ongoing.
+         *
+         * In theory, cancel() could execute arbitrary listeners -- bad to do while holding a lock.
+         * However, we don't expose currentFuture to users, so they can't attach listeners. And the
+         * Future might not even be a ListenableFuture, just a plain Future. That said, similar
+         * problems can exist with methods like FutureTask.done(), not to mention slow calls to
+         * Thread.interrupt() (as discussed in InterruptibleTask). At the end of the day, it's
+         * unlikely that cancel() will be slow, so we can probably get away with calling it while
+         * holding a lock. Still, it would be nice to avoid somehow.
+         */
         lock.lock();
         try {
-          return currentFuture.cancel(mayInterruptIfRunning);
+          currentFuture.cancel(mayInterruptIfRunning);
         } finally {
           lock.unlock();
         }
@@ -542,20 +654,12 @@ public boolean isCancelled() {
           lock.unlock();
         }
       }
-
-      @Override
-      protected Future<Void> delegate() {
-        throw new UnsupportedOperationException(
-            "Only cancel and isCancelled is supported by this future");
-      }
     }
 
     @Override
-    final Future<?> schedule(
+    final Cancellable schedule(
         AbstractService service, ScheduledExecutorService executor, Runnable runnable) {
-      ReschedulableCallable task = new ReschedulableCallable(service, executor, runnable);
-      task.reschedule();
-      return task;
+      return new ReschedulableCallable(service, executor, runnable).reschedule();
     }
 
     /**
diff --git a/android/guava/src/com/google/common/util/concurrent/AbstractService.java b/android/guava/src/com/google/common/util/concurrent/AbstractService.java
index 733bf3b77813..1cf31bf915a6 100644
--- a/android/guava/src/com/google/common/util/concurrent/AbstractService.java
+++ b/android/guava/src/com/google/common/util/concurrent/AbstractService.java
@@ -23,6 +23,7 @@
 import static com.google.common.util.concurrent.Service.State.STARTING;
 import static com.google.common.util.concurrent.Service.State.STOPPING;
 import static com.google.common.util.concurrent.Service.State.TERMINATED;
+import static java.util.Objects.requireNonNull;
 
 import com.google.common.annotations.Beta;
 import com.google.common.annotations.GwtIncompatible;
@@ -35,7 +36,7 @@
 import java.util.concurrent.Executor;
 import java.util.concurrent.TimeUnit;
 import java.util.concurrent.TimeoutException;
-import org.checkerframework.checker.nullness.compatqual.NullableDecl;
+import javax.annotation.CheckForNull;
 
 /**
  * Base class for implementing services that can handle {@link #doStart} and {@link #doStop}
@@ -48,6 +49,7 @@
  * @since 1.0
  */
 @GwtIncompatible
+@ElementTypesAreNonnullByDefault
 public abstract class AbstractService implements Service {
   private static final ListenerCallQueue.Event<Listener> STARTING_EVENT =
       new ListenerCallQueue.Event<Listener>() {
@@ -169,7 +171,7 @@ private final class IsStoppedGuard extends Guard {
 
     @Override
     public boolean isSatisfied() {
-      return state().isTerminal();
+      return state().compareTo(TERMINATED) >= 0;
     }
   }
 
@@ -575,20 +577,20 @@ private static final class StateSnapshot {
      * The exception that caused this service to fail. This will be {@code null} unless the service
      * has failed.
      */
-    @NullableDecl final Throwable failure;
+    @CheckForNull final Throwable failure;
 
     StateSnapshot(State internalState) {
       this(internalState, false, null);
     }
 
     StateSnapshot(
-        State internalState, boolean shutdownWhenStartupFinishes, @NullableDecl Throwable failure) {
+        State internalState, boolean shutdownWhenStartupFinishes, @CheckForNull Throwable failure) {
       checkArgument(
           !shutdownWhenStartupFinishes || internalState == STARTING,
           "shutdownWhenStartupFinishes can only be set if state is STARTING. Got %s instead.",
           internalState);
       checkArgument(
-          !(failure != null ^ internalState == FAILED),
+          (failure != null) == (internalState == FAILED),
           "A failure cause should be set if and only if the state is failed.  Got %s and %s "
               + "instead.",
           internalState,
@@ -613,7 +615,8 @@ Throwable failureCause() {
           state == FAILED,
           "failureCause() is only valid if the service has failed, service is %s",
           state);
-      return failure;
+      // requireNonNull is safe because the constructor requires a non-null cause with state=FAILED.
+      return requireNonNull(failure);
     }
   }
 }
diff --git a/android/guava/src/com/google/common/util/concurrent/AbstractTransformFuture.java b/android/guava/src/com/google/common/util/concurrent/AbstractTransformFuture.java
index 4b908dc2cc2e..dd68791594ae 100644
--- a/android/guava/src/com/google/common/util/concurrent/AbstractTransformFuture.java
+++ b/android/guava/src/com/google/common/util/concurrent/AbstractTransformFuture.java
@@ -24,13 +24,17 @@
 import java.util.concurrent.CancellationException;
 import java.util.concurrent.ExecutionException;
 import java.util.concurrent.Executor;
-import org.checkerframework.checker.nullness.compatqual.NullableDecl;
+import javax.annotation.CheckForNull;
+import org.checkerframework.checker.nullness.qual.Nullable;
 
 /** Implementations of {@code Futures.transform*}. */
 @GwtCompatible
-abstract class AbstractTransformFuture<I, O, F, T> extends FluentFuture.TrustedFuture<O>
-    implements Runnable {
-  static <I, O> ListenableFuture<O> create(
+@ElementTypesAreNonnullByDefault
+@SuppressWarnings("nullness") // TODO(b/147136275): Remove once our checker understands & and |.
+abstract class AbstractTransformFuture<
+        I extends @Nullable Object, O extends @Nullable Object, F, T extends @Nullable Object>
+    extends FluentFuture.TrustedFuture<O> implements Runnable {
+  static <I extends @Nullable Object, O extends @Nullable Object> ListenableFuture<O> create(
       ListenableFuture<I> input,
       AsyncFunction<? super I, ? extends O> function,
       Executor executor) {
@@ -40,7 +44,7 @@ static <I, O> ListenableFuture<O> create(
     return output;
   }
 
-  static <I, O> ListenableFuture<O> create(
+  static <I extends @Nullable Object, O extends @Nullable Object> ListenableFuture<O> create(
       ListenableFuture<I> input, Function<? super I, ? extends O> function, Executor executor) {
     checkNotNull(function);
     TransformFuture<I, O> output = new TransformFuture<>(input, function);
@@ -52,8 +56,8 @@ static <I, O> ListenableFuture<O> create(
    * In certain circumstances, this field might theoretically not be visible to an afterDone() call
    * triggered by cancel(). For details, see the comments on the fields of TimeoutFuture.
    */
-  @NullableDecl ListenableFuture<? extends I> inputFuture;
-  @NullableDecl F function;
+  @CheckForNull ListenableFuture<? extends I> inputFuture;
+  @CheckForNull F function;
 
   AbstractTransformFuture(ListenableFuture<? extends I> inputFuture, F function) {
     this.inputFuture = checkNotNull(inputFuture);
@@ -165,12 +169,12 @@ public final void run() {
 
   /** Template method for subtypes to actually run the transform. */
   @ForOverride
-  @NullableDecl
-  abstract T doTransform(F function, @NullableDecl I result) throws Exception;
+  @ParametricNullness
+  abstract T doTransform(F function, @ParametricNullness I result) throws Exception;
 
   /** Template method for subtypes to actually set the result. */
   @ForOverride
-  abstract void setResult(@NullableDecl T result);
+  abstract void setResult(@ParametricNullness T result);
 
   @Override
   protected final void afterDone() {
@@ -180,6 +184,7 @@ protected final void afterDone() {
   }
 
   @Override
+  @CheckForNull
   protected String pendingToString() {
     ListenableFuture<? extends I> localInputFuture = inputFuture;
     F localFunction = function;
@@ -200,7 +205,8 @@ protected String pendingToString() {
    * An {@link AbstractTransformFuture} that delegates to an {@link AsyncFunction} and {@link
    * #setFuture(ListenableFuture)}.
    */
-  private static final class AsyncTransformFuture<I, O>
+  private static final class AsyncTransformFuture<
+          I extends @Nullable Object, O extends @Nullable Object>
       extends AbstractTransformFuture<
           I, O, AsyncFunction<? super I, ? extends O>, ListenableFuture<? extends O>> {
     AsyncTransformFuture(
@@ -210,7 +216,8 @@ private static final class AsyncTransformFuture<I, O>
 
     @Override
     ListenableFuture<? extends O> doTransform(
-        AsyncFunction<? super I, ? extends O> function, @NullableDecl I input) throws Exception {
+        AsyncFunction<? super I, ? extends O> function, @ParametricNullness I input)
+        throws Exception {
       ListenableFuture<? extends O> outputFuture = function.apply(input);
       checkNotNull(
           outputFuture,
@@ -230,7 +237,7 @@ void setResult(ListenableFuture<? extends O> result) {
    * An {@link AbstractTransformFuture} that delegates to a {@link Function} and {@link
    * #set(Object)}.
    */
-  private static final class TransformFuture<I, O>
+  private static final class TransformFuture<I extends @Nullable Object, O extends @Nullable Object>
       extends AbstractTransformFuture<I, O, Function<? super I, ? extends O>, O> {
     TransformFuture(
         ListenableFuture<? extends I> inputFuture, Function<? super I, ? extends O> function) {
@@ -238,13 +245,13 @@ private static final class TransformFuture<I, O>
     }
 
     @Override
-    @NullableDecl
-    O doTransform(Function<? super I, ? extends O> function, @NullableDecl I input) {
+    @ParametricNullness
+    O doTransform(Function<? super I, ? extends O> function, @ParametricNullness I input) {
       return function.apply(input);
     }
 
     @Override
-    void setResult(@NullableDecl O result) {
+    void setResult(@ParametricNullness O result) {
       set(result);
     }
   }
diff --git a/android/guava/src/com/google/common/util/concurrent/AggregateFuture.java b/android/guava/src/com/google/common/util/concurrent/AggregateFuture.java
index acc1f2d0b210..6d2ed9c8e8cd 100644
--- a/android/guava/src/com/google/common/util/concurrent/AggregateFuture.java
+++ b/android/guava/src/com/google/common/util/concurrent/AggregateFuture.java
@@ -20,6 +20,7 @@
 import static com.google.common.util.concurrent.AggregateFuture.ReleaseResourcesReason.OUTPUT_FUTURE_DONE;
 import static com.google.common.util.concurrent.Futures.getDone;
 import static com.google.common.util.concurrent.MoreExecutors.directExecutor;
+import static java.util.Objects.requireNonNull;
 import static java.util.logging.Level.SEVERE;
 
 import com.google.common.annotations.GwtCompatible;
@@ -30,7 +31,8 @@
 import java.util.concurrent.ExecutionException;
 import java.util.concurrent.Future;
 import java.util.logging.Logger;
-import org.checkerframework.checker.nullness.compatqual.NullableDecl;
+import javax.annotation.CheckForNull;
+import org.checkerframework.checker.nullness.qual.Nullable;
 
 /**
  * A future whose value is derived from a collection of input futures.
@@ -39,7 +41,9 @@
  * @param <OutputT> the type of the output (i.e. this) future
  */
 @GwtCompatible
-abstract class AggregateFuture<InputT, OutputT> extends AggregateFutureState<OutputT> {
+@ElementTypesAreNonnullByDefault
+abstract class AggregateFuture<InputT extends @Nullable Object, OutputT extends @Nullable Object>
+    extends AggregateFutureState<OutputT> {
   private static final Logger logger = Logger.getLogger(AggregateFuture.class.getName());
 
   /**
@@ -52,7 +56,7 @@ abstract class AggregateFuture<InputT, OutputT> extends AggregateFutureState<Out
    * In certain circumstances, this field might theoretically not be visible to an afterDone() call
    * triggered by cancel(). For details, see the comments on the fields of TimeoutFuture.
    */
-  @NullableDecl private ImmutableCollection<? extends ListenableFuture<? extends InputT>> futures;
+  @CheckForNull private ImmutableCollection<? extends ListenableFuture<? extends InputT>> futures;
 
   private final boolean allMustSucceed;
   private final boolean collectsValues;
@@ -87,6 +91,7 @@ protected final void afterDone() {
   }
 
   @Override
+  @CheckForNull
   protected final String pendingToString() {
     ImmutableCollection<? extends Future<?>> localFutures = futures;
     if (localFutures != null) {
@@ -103,6 +108,13 @@ protected final String pendingToString() {
    * we're guaranteed to have properly initialized the subclass.
    */
   final void init() {
+    /*
+     * requireNonNull is safe because this is called from the constructor after `futures` is set but
+     * before releaseResources could be called (because we have not yet set up any of the listeners
+     * that could call it, nor exposed this Future for users to call cancel() on).
+     */
+    requireNonNull(futures);
+
     // Corner case: List is empty.
     if (futures.isEmpty()) {
       handleAllCompleted();
@@ -123,29 +135,26 @@ final void init() {
       // This is not actually a problem, since the foreach only needs this.futures to be non-null
       // at the beginning of the loop.
       int i = 0;
-      for (final ListenableFuture<? extends InputT> future : futures) {
-        final int index = i++;
+      for (ListenableFuture<? extends InputT> future : futures) {
+        int index = i++;
         future.addListener(
-            new Runnable() {
-              @Override
-              public void run() {
-                try {
-                  if (future.isCancelled()) {
-                    // Clear futures prior to cancelling children. This sets our own state but lets
-                    // the input futures keep running, as some of them may be used elsewhere.
-                    futures = null;
-                    cancel(false);
-                  } else {
-                    collectValueFromNonCancelledFuture(index, future);
-                  }
-                } finally {
-                  /*
-                   * "null" means: There is no need to access `futures` again during
-                   * `processCompleted` because we're reading each value during a call to
-                   * handleOneInputDone.
-                   */
-                  decrementCountAndMaybeComplete(null);
+            () -> {
+              try {
+                if (future.isCancelled()) {
+                  // Clear futures prior to cancelling children. This sets our own state but lets
+                  // the input futures keep running, as some of them may be used elsewhere.
+                  futures = null;
+                  cancel(false);
+                } else {
+                  collectValueFromNonCancelledFuture(index, future);
                 }
+              } finally {
+                /*
+                 * "null" means: There is no need to access `futures` again during
+                 * `processCompleted` because we're reading each value during a call to
+                 * handleOneInputDone.
+                 */
+                decrementCountAndMaybeComplete(null);
               }
             },
             directExecutor());
@@ -167,15 +176,9 @@ public void run() {
        * could actually hurt in some cases, as it forces us to keep all inputs in memory until the
        * final input completes.
        */
-      final ImmutableCollection<? extends Future<? extends InputT>> localFutures =
+      ImmutableCollection<? extends Future<? extends InputT>> localFutures =
           collectsValues ? futures : null;
-      Runnable listener =
-          new Runnable() {
-            @Override
-            public void run() {
-              decrementCountAndMaybeComplete(localFutures);
-            }
-          };
+      Runnable listener = () -> decrementCountAndMaybeComplete(localFutures);
       for (ListenableFuture<? extends InputT> future : futures) {
         future.addListener(listener, directExecutor());
       }
@@ -222,12 +225,11 @@ private void handleException(Throwable throwable) {
     }
   }
 
-  private void log(Throwable throwable) {
+  private static void log(Throwable throwable) {
     String message =
         (throwable instanceof Error)
             ? "Input Future failed with Error"
-            : "An additional input failed after the first. Logging it after adding the first"
-                + " failure as a suppressed exception.";
+            : "Got more than one input Future failure. Logging failures after the first";
     logger.log(SEVERE, message, throwable);
   }
 
@@ -235,8 +237,24 @@ private void log(Throwable throwable) {
   final void addInitialException(Set<Throwable> seen) {
     checkNotNull(seen);
     if (!isCancelled()) {
-      // TODO(cpovirk): Think about whether we could/should use Verify to check this.
-      boolean unused = addCausalChain(seen, tryInternalFastPathGetFailure());
+      /*
+       * requireNonNull is safe because:
+       *
+       * - This is a TrustedFuture, so tryInternalFastPathGetFailure will in fact return the failure
+       *   cause if this Future has failed.
+       *
+       * - And this future *has* failed: This method is called only from handleException (through
+       *   getOrInitSeenExceptions). handleException tried to call setException and failed, so
+       *   either this Future was cancelled (which we ruled out with the isCancelled check above),
+       *   or it had already failed. (It couldn't have completed *successfully* or even had
+       *   setFuture called on it: Neither of those can happen until we've finished processing all
+       *   the completed inputs. And we're still processing at least one input, the one that
+       *   triggered handleException.)
+       *
+       * TODO(cpovirk): Think about whether we could/should use Verify to check the return value of
+       * addCausalChain.
+       */
+      boolean unused = addCausalChain(seen, requireNonNull(tryInternalFastPathGetFailure()));
     }
   }
 
@@ -256,7 +274,7 @@ private void collectValueFromNonCancelledFuture(int index, Future<? extends Inpu
   }
 
   private void decrementCountAndMaybeComplete(
-      @NullableDecl
+      @CheckForNull
           ImmutableCollection<? extends Future<? extends InputT>>
               futuresIfNeedToCollectAtCompletion) {
     int newRemaining = decrementRemainingAndGet();
@@ -267,7 +285,7 @@ private void decrementCountAndMaybeComplete(
   }
 
   private void processCompleted(
-      @NullableDecl
+      @CheckForNull
           ImmutableCollection<? extends Future<? extends InputT>>
               futuresIfNeedToCollectAtCompletion) {
     if (futuresIfNeedToCollectAtCompletion != null) {
@@ -323,12 +341,15 @@ enum ReleaseResourcesReason {
    * If {@code allMustSucceed} is true, called as each future completes; otherwise, if {@code
    * collectsValues} is true, called for each future when all futures complete.
    */
-  abstract void collectOneValue(int index, @NullableDecl InputT returnValue);
+  abstract void collectOneValue(int index, @ParametricNullness InputT returnValue);
 
   abstract void handleAllCompleted();
 
   /** Adds the chain to the seen set, and returns whether all the chain was new to us. */
-  private static boolean addCausalChain(Set<Throwable> seen, Throwable t) {
+  private static boolean addCausalChain(Set<Throwable> seen, Throwable param) {
+    // Declare a "true" local variable so that the Checker Framework will infer nullness.
+    Throwable t = param;
+
     for (; t != null; t = t.getCause()) {
       boolean firstTimeSeen = seen.add(t);
       if (!firstTimeSeen) {
diff --git a/android/guava/src/com/google/common/util/concurrent/AggregateFutureState.java b/android/guava/src/com/google/common/util/concurrent/AggregateFutureState.java
index f8398d817eb2..ee23ca021e97 100644
--- a/android/guava/src/com/google/common/util/concurrent/AggregateFutureState.java
+++ b/android/guava/src/com/google/common/util/concurrent/AggregateFutureState.java
@@ -15,6 +15,7 @@
 package com.google.common.util.concurrent;
 
 import static com.google.common.collect.Sets.newConcurrentHashSet;
+import static java.util.Objects.requireNonNull;
 import static java.util.concurrent.atomic.AtomicIntegerFieldUpdater.newUpdater;
 import static java.util.concurrent.atomic.AtomicReferenceFieldUpdater.newUpdater;
 
@@ -25,6 +26,8 @@
 import java.util.concurrent.atomic.AtomicReferenceFieldUpdater;
 import java.util.logging.Level;
 import java.util.logging.Logger;
+import javax.annotation.CheckForNull;
+import org.checkerframework.checker.nullness.qual.Nullable;
 
 /**
  * A helper which does some thread-safe operations for aggregate futures, which must be implemented
@@ -37,10 +40,12 @@
  */
 @GwtCompatible(emulated = true)
 @ReflectionSupport(value = ReflectionSupport.Level.FULL)
-abstract class AggregateFutureState<OutputT> extends AbstractFuture.TrustedFuture<OutputT> {
+@ElementTypesAreNonnullByDefault
+abstract class AggregateFutureState<OutputT extends @Nullable Object>
+    extends AbstractFuture.TrustedFuture<OutputT> {
   // Lazily initialized the first time we see an exception; not released until all the input futures
   // have completed and we have processed them all.
-  private volatile Set<Throwable> seenExceptions = null;
+  @CheckForNull private volatile Set<Throwable> seenExceptions = null;
 
   private volatile int remaining;
 
@@ -54,7 +59,7 @@ abstract class AggregateFutureState<OutputT> extends AbstractFuture.TrustedFutur
     try {
       helper =
           new SafeAtomicHelper(
-              newUpdater(AggregateFutureState.class, (Class) Set.class, "seenExceptions"),
+              newUpdater(AggregateFutureState.class, Set.class, "seenExceptions"),
               newUpdater(AggregateFutureState.class, "remaining"));
     } catch (Throwable reflectionFailure) {
       // Some Android 5.0.x Samsung devices have bugs in JDK reflection APIs that cause
@@ -124,8 +129,11 @@ final Set<Throwable> getOrInitSeenExceptions() {
        * other callers have added to it.
        *
        * This read is guaranteed to get us the right value because we only set this once (here).
+       *
+       * requireNonNull is safe because either our compareAndSet succeeded or it failed because
+       * another thread did it for us.
        */
-      seenExceptionsLocal = seenExceptions;
+      seenExceptionsLocal = requireNonNull(seenExceptions);
     }
     return seenExceptionsLocal;
   }
@@ -144,32 +152,37 @@ final void clearSeenExceptions() {
   private abstract static class AtomicHelper {
     /** Atomic compare-and-set of the {@link AggregateFutureState#seenExceptions} field. */
     abstract void compareAndSetSeenExceptions(
-        AggregateFutureState state, Set<Throwable> expect, Set<Throwable> update);
+        AggregateFutureState<?> state, @CheckForNull Set<Throwable> expect, Set<Throwable> update);
 
     /** Atomic decrement-and-get of the {@link AggregateFutureState#remaining} field. */
-    abstract int decrementAndGetRemainingCount(AggregateFutureState state);
+    abstract int decrementAndGetRemainingCount(AggregateFutureState<?> state);
   }
 
   private static final class SafeAtomicHelper extends AtomicHelper {
-    final AtomicReferenceFieldUpdater<AggregateFutureState, Set<Throwable>> seenExceptionsUpdater;
+    final AtomicReferenceFieldUpdater<AggregateFutureState<?>, Set<Throwable>>
+        seenExceptionsUpdater;
 
-    final AtomicIntegerFieldUpdater<AggregateFutureState> remainingCountUpdater;
+    final AtomicIntegerFieldUpdater<AggregateFutureState<?>> remainingCountUpdater;
 
+    @SuppressWarnings({"rawtypes", "unchecked"}) // Unavoidable with reflection API
     SafeAtomicHelper(
         AtomicReferenceFieldUpdater seenExceptionsUpdater,
         AtomicIntegerFieldUpdater remainingCountUpdater) {
-      this.seenExceptionsUpdater = seenExceptionsUpdater;
-      this.remainingCountUpdater = remainingCountUpdater;
+      this.seenExceptionsUpdater =
+          (AtomicReferenceFieldUpdater<AggregateFutureState<?>, Set<Throwable>>)
+              seenExceptionsUpdater;
+      this.remainingCountUpdater =
+          (AtomicIntegerFieldUpdater<AggregateFutureState<?>>) remainingCountUpdater;
     }
 
     @Override
     void compareAndSetSeenExceptions(
-        AggregateFutureState state, Set<Throwable> expect, Set<Throwable> update) {
+        AggregateFutureState<?> state, @CheckForNull Set<Throwable> expect, Set<Throwable> update) {
       seenExceptionsUpdater.compareAndSet(state, expect, update);
     }
 
     @Override
-    int decrementAndGetRemainingCount(AggregateFutureState state) {
+    int decrementAndGetRemainingCount(AggregateFutureState<?> state) {
       return remainingCountUpdater.decrementAndGet(state);
     }
   }
@@ -177,7 +190,7 @@ int decrementAndGetRemainingCount(AggregateFutureState state) {
   private static final class SynchronizedAtomicHelper extends AtomicHelper {
     @Override
     void compareAndSetSeenExceptions(
-        AggregateFutureState state, Set<Throwable> expect, Set<Throwable> update) {
+        AggregateFutureState<?> state, @CheckForNull Set<Throwable> expect, Set<Throwable> update) {
       synchronized (state) {
         if (state.seenExceptions == expect) {
           state.seenExceptions = update;
@@ -186,7 +199,7 @@ void compareAndSetSeenExceptions(
     }
 
     @Override
-    int decrementAndGetRemainingCount(AggregateFutureState state) {
+    int decrementAndGetRemainingCount(AggregateFutureState<?> state) {
       synchronized (state) {
         return --state.remaining;
       }
diff --git a/android/guava/src/com/google/common/util/concurrent/AsyncCallable.java b/android/guava/src/com/google/common/util/concurrent/AsyncCallable.java
index 99807de386c9..99167db07724 100644
--- a/android/guava/src/com/google/common/util/concurrent/AsyncCallable.java
+++ b/android/guava/src/com/google/common/util/concurrent/AsyncCallable.java
@@ -14,9 +14,9 @@
 
 package com.google.common.util.concurrent;
 
-import com.google.common.annotations.Beta;
 import com.google.common.annotations.GwtCompatible;
 import java.util.concurrent.Future;
+import org.checkerframework.checker.nullness.qual.Nullable;
 
 /**
  * Computes a value, possibly asynchronously. For an example usage and more information, see {@link
@@ -27,9 +27,9 @@
  *
  * @since 20.0
  */
-@Beta
 @GwtCompatible
-public interface AsyncCallable<V> {
+@ElementTypesAreNonnullByDefault
+public interface AsyncCallable<V extends @Nullable Object> {
   /**
    * Computes a result {@code Future}. The output {@code Future} need not be {@linkplain
    * Future#isDone done}, making {@code AsyncCallable} suitable for asynchronous derivations.
diff --git a/android/guava/src/com/google/common/util/concurrent/AsyncFunction.java b/android/guava/src/com/google/common/util/concurrent/AsyncFunction.java
index 67c3cc289b54..cd70d20dc515 100644
--- a/android/guava/src/com/google/common/util/concurrent/AsyncFunction.java
+++ b/android/guava/src/com/google/common/util/concurrent/AsyncFunction.java
@@ -16,7 +16,7 @@
 
 import com.google.common.annotations.GwtCompatible;
 import java.util.concurrent.Future;
-import org.checkerframework.checker.nullness.compatqual.NullableDecl;
+import org.checkerframework.checker.nullness.qual.Nullable;
 
 /**
  * Transforms a value, possibly asynchronously. For an example usage and more information, see
@@ -26,7 +26,8 @@
  * @since 11.0
  */
 @GwtCompatible
-public interface AsyncFunction<I, O> {
+@ElementTypesAreNonnullByDefault
+public interface AsyncFunction<I extends @Nullable Object, O extends @Nullable Object> {
   /**
    * Returns an output {@code Future} to use in place of the given {@code input}. The output {@code
    * Future} need not be {@linkplain Future#isDone done}, making {@code AsyncFunction} suitable for
@@ -34,5 +35,5 @@ public interface AsyncFunction<I, O> {
    *
    * <p>Throwing an exception from this method is equivalent to returning a failing {@code Future}.
    */
-  ListenableFuture<O> apply(@NullableDecl I input) throws Exception;
+  ListenableFuture<O> apply(@ParametricNullness I input) throws Exception;
 }
diff --git a/android/guava/src/com/google/common/util/concurrent/AtomicDouble.java b/android/guava/src/com/google/common/util/concurrent/AtomicDouble.java
index 563381bf1008..0da3715bea1b 100644
--- a/android/guava/src/com/google/common/util/concurrent/AtomicDouble.java
+++ b/android/guava/src/com/google/common/util/concurrent/AtomicDouble.java
@@ -49,6 +49,7 @@
  * @author Martin Buchholz
  * @since 11.0
  */
+@ElementTypesAreNonnullByDefault
 public class AtomicDouble extends Number implements java.io.Serializable {
   private static final long serialVersionUID = 0L;
 
@@ -163,6 +164,7 @@ public final double getAndAdd(double delta) {
    *
    * @param delta the value to add
    * @return the updated value
+   * @since 31.1
    */
   @CanIgnoreReturnValue
   public final double addAndGet(double delta) {
diff --git a/android/guava/src/com/google/common/util/concurrent/AtomicDoubleArray.java b/android/guava/src/com/google/common/util/concurrent/AtomicDoubleArray.java
index 5c4baa163aab..fc8deed3b0d1 100644
--- a/android/guava/src/com/google/common/util/concurrent/AtomicDoubleArray.java
+++ b/android/guava/src/com/google/common/util/concurrent/AtomicDoubleArray.java
@@ -44,6 +44,7 @@
  * @since 11.0
  */
 @GwtIncompatible
+@ElementTypesAreNonnullByDefault
 public class AtomicDoubleArray implements java.io.Serializable {
   private static final long serialVersionUID = 0L;
 
@@ -68,7 +69,7 @@ public AtomicDoubleArray(int length) {
    * @throws NullPointerException if array is null
    */
   public AtomicDoubleArray(double[] array) {
-    final int len = array.length;
+    int len = array.length;
     long[] longArray = new long[len];
     for (int i = 0; i < len; i++) {
       longArray[i] = doubleToRawLongBits(array[i]);
@@ -96,7 +97,7 @@ public final double get(int i) {
   }
 
   /**
-   * Sets the element at position {@code i} to the given value.
+   * Atomically sets the element at position {@code i} to the given value.
    *
    * @param i the index
    * @param newValue the new value
@@ -187,6 +188,7 @@ public final double getAndAdd(int i, double delta) {
    * @param i the index
    * @param delta the value to add
    * @return the updated value
+   * @since 31.1
    */
   @CanIgnoreReturnValue
   public double addAndGet(int i, double delta) {
diff --git a/android/guava/src/com/google/common/util/concurrent/AtomicLongMap.java b/android/guava/src/com/google/common/util/concurrent/AtomicLongMap.java
index 7fc58f47fc4f..bac02c1436fe 100644
--- a/android/guava/src/com/google/common/util/concurrent/AtomicLongMap.java
+++ b/android/guava/src/com/google/common/util/concurrent/AtomicLongMap.java
@@ -28,7 +28,7 @@
 import java.util.Map.Entry;
 import java.util.concurrent.ConcurrentHashMap;
 import java.util.concurrent.atomic.AtomicLong;
-import org.checkerframework.checker.nullness.compatqual.NullableDecl;
+import javax.annotation.CheckForNull;
 
 /**
  * A map containing {@code long} values that can be atomically updated. While writes to a
@@ -54,6 +54,7 @@
  * @since 11.0
  */
 @GwtCompatible
+@ElementTypesAreNonnullByDefault
 public final class AtomicLongMap<K> implements Serializable {
   private final ConcurrentHashMap<K, AtomicLong> map;
 
@@ -325,7 +326,7 @@ public long sum() {
     return sum;
   }
 
-  @NullableDecl private transient Map<K, Long> asMap;
+  @CheckForNull private transient Map<K, Long> asMap;
 
   /** Returns a live, read-only view of the map backing this {@code AtomicLongMap}. */
   public Map<K, Long> asMap() {
diff --git a/android/guava/src/com/google/common/util/concurrent/Atomics.java b/android/guava/src/com/google/common/util/concurrent/Atomics.java
index f6aafb743120..c1b6964ec23c 100644
--- a/android/guava/src/com/google/common/util/concurrent/Atomics.java
+++ b/android/guava/src/com/google/common/util/concurrent/Atomics.java
@@ -17,7 +17,7 @@
 import com.google.common.annotations.GwtIncompatible;
 import java.util.concurrent.atomic.AtomicReference;
 import java.util.concurrent.atomic.AtomicReferenceArray;
-import org.checkerframework.checker.nullness.compatqual.NullableDecl;
+import org.checkerframework.checker.nullness.qual.Nullable;
 
 /**
  * Static utility methods pertaining to classes in the {@code java.util.concurrent.atomic} package.
@@ -26,6 +26,7 @@
  * @since 10.0
  */
 @GwtIncompatible
+@ElementTypesAreNonnullByDefault
 public final class Atomics {
   private Atomics() {}
 
@@ -34,8 +35,8 @@ private Atomics() {}
    *
    * @return a new {@code AtomicReference} with no initial value
    */
-  public static <V> AtomicReference<V> newReference() {
-    return new AtomicReference<V>();
+  public static <V> AtomicReference<@Nullable V> newReference() {
+    return new AtomicReference<>();
   }
 
   /**
@@ -44,8 +45,9 @@ public static <V> AtomicReference<V> newReference() {
    * @param initialValue the initial value
    * @return a new {@code AtomicReference} with the given initial value
    */
-  public static <V> AtomicReference<V> newReference(@NullableDecl V initialValue) {
-    return new AtomicReference<V>(initialValue);
+  public static <V extends @Nullable Object> AtomicReference<V> newReference(
+      @ParametricNullness V initialValue) {
+    return new AtomicReference<>(initialValue);
   }
 
   /**
@@ -54,8 +56,8 @@ public static <V> AtomicReference<V> newReference(@NullableDecl V initialValue)
    * @param length the length of the array
    * @return a new {@code AtomicReferenceArray} with the given length
    */
-  public static <E> AtomicReferenceArray<E> newReferenceArray(int length) {
-    return new AtomicReferenceArray<E>(length);
+  public static <E> AtomicReferenceArray<@Nullable E> newReferenceArray(int length) {
+    return new AtomicReferenceArray<>(length);
   }
 
   /**
@@ -65,7 +67,7 @@ public static <E> AtomicReferenceArray<E> newReferenceArray(int length) {
    * @param array the array to copy elements from
    * @return a new {@code AtomicReferenceArray} copied from the given array
    */
-  public static <E> AtomicReferenceArray<E> newReferenceArray(E[] array) {
-    return new AtomicReferenceArray<E>(array);
+  public static <E extends @Nullable Object> AtomicReferenceArray<E> newReferenceArray(E[] array) {
+    return new AtomicReferenceArray<>(array);
   }
 }
diff --git a/android/guava/src/com/google/common/util/concurrent/Callables.java b/android/guava/src/com/google/common/util/concurrent/Callables.java
index b6678860cdcf..3b52c2e98217 100644
--- a/android/guava/src/com/google/common/util/concurrent/Callables.java
+++ b/android/guava/src/com/google/common/util/concurrent/Callables.java
@@ -21,7 +21,7 @@
 import com.google.common.annotations.GwtIncompatible;
 import com.google.common.base.Supplier;
 import java.util.concurrent.Callable;
-import org.checkerframework.checker.nullness.compatqual.NullableDecl;
+import org.checkerframework.checker.nullness.qual.Nullable;
 
 /**
  * Static utility methods pertaining to the {@link Callable} interface.
@@ -30,17 +30,13 @@
  * @since 1.0
  */
 @GwtCompatible(emulated = true)
+@ElementTypesAreNonnullByDefault
 public final class Callables {
   private Callables() {}
 
   /** Creates a {@code Callable} which immediately returns a preset value each time it is called. */
-  public static <T> Callable<T> returning(@NullableDecl final T value) {
-    return new Callable<T>() {
-      @Override
-      public T call() {
-        return value;
-      }
-    };
+  public static <T extends @Nullable Object> Callable<T> returning(@ParametricNullness T value) {
+    return () -> value;
   }
 
   /**
@@ -53,16 +49,11 @@ public T call() {
    */
   @Beta
   @GwtIncompatible
-  public static <T> AsyncCallable<T> asAsyncCallable(
-      final Callable<T> callable, final ListeningExecutorService listeningExecutorService) {
+  public static <T extends @Nullable Object> AsyncCallable<T> asAsyncCallable(
+      Callable<T> callable, ListeningExecutorService listeningExecutorService) {
     checkNotNull(callable);
     checkNotNull(listeningExecutorService);
-    return new AsyncCallable<T>() {
-      @Override
-      public ListenableFuture<T> call() throws Exception {
-        return listeningExecutorService.submit(callable);
-      }
-    };
+    return () -> listeningExecutorService.submit(callable);
   }
 
   /**
@@ -74,22 +65,19 @@ public ListenableFuture<T> call() throws Exception {
    *     for each invocation of the wrapped callable.
    */
   @GwtIncompatible // threads
-  static <T> Callable<T> threadRenaming(
-      final Callable<T> callable, final Supplier<String> nameSupplier) {
+  static <T extends @Nullable Object> Callable<T> threadRenaming(
+      Callable<T> callable, Supplier<String> nameSupplier) {
     checkNotNull(nameSupplier);
     checkNotNull(callable);
-    return new Callable<T>() {
-      @Override
-      public T call() throws Exception {
-        Thread currentThread = Thread.currentThread();
-        String oldName = currentThread.getName();
-        boolean restoreName = trySetName(nameSupplier.get(), currentThread);
-        try {
-          return callable.call();
-        } finally {
-          if (restoreName) {
-            boolean unused = trySetName(oldName, currentThread);
-          }
+    return () -> {
+      Thread currentThread = Thread.currentThread();
+      String oldName = currentThread.getName();
+      boolean restoreName = trySetName(nameSupplier.get(), currentThread);
+      try {
+        return callable.call();
+      } finally {
+        if (restoreName) {
+          boolean unused = trySetName(oldName, currentThread);
         }
       }
     };
@@ -104,21 +92,18 @@ public T call() throws Exception {
    *     for each invocation of the wrapped callable.
    */
   @GwtIncompatible // threads
-  static Runnable threadRenaming(final Runnable task, final Supplier<String> nameSupplier) {
+  static Runnable threadRenaming(Runnable task, Supplier<String> nameSupplier) {
     checkNotNull(nameSupplier);
     checkNotNull(task);
-    return new Runnable() {
-      @Override
-      public void run() {
-        Thread currentThread = Thread.currentThread();
-        String oldName = currentThread.getName();
-        boolean restoreName = trySetName(nameSupplier.get(), currentThread);
-        try {
-          task.run();
-        } finally {
-          if (restoreName) {
-            boolean unused = trySetName(oldName, currentThread);
-          }
+    return () -> {
+      Thread currentThread = Thread.currentThread();
+      String oldName = currentThread.getName();
+      boolean restoreName = trySetName(nameSupplier.get(), currentThread);
+      try {
+        task.run();
+      } finally {
+        if (restoreName) {
+          boolean unused = trySetName(oldName, currentThread);
         }
       }
     };
@@ -126,7 +111,7 @@ public void run() {
 
   /** Tries to set name of the given {@link Thread}, returns true if successful. */
   @GwtIncompatible // threads
-  private static boolean trySetName(final String threadName, Thread currentThread) {
+  private static boolean trySetName(String threadName, Thread currentThread) {
     /*
      * setName should usually succeed, but the security manager can prohibit it. Is there a way to
      * see if we have the modifyThread permission without catching an exception?
diff --git a/android/guava/src/com/google/common/util/concurrent/ClosingFuture.java b/android/guava/src/com/google/common/util/concurrent/ClosingFuture.java
index 5969c4ff7d2e..b8aec0337c57 100644
--- a/android/guava/src/com/google/common/util/concurrent/ClosingFuture.java
+++ b/android/guava/src/com/google/common/util/concurrent/ClosingFuture.java
@@ -36,7 +36,6 @@
 import static java.util.logging.Level.SEVERE;
 import static java.util.logging.Level.WARNING;
 
-import com.google.common.annotations.Beta;
 import com.google.common.annotations.VisibleForTesting;
 import com.google.common.base.Function;
 import com.google.common.collect.FluentIterable;
@@ -60,7 +59,8 @@
 import java.util.concurrent.RejectedExecutionException;
 import java.util.concurrent.atomic.AtomicReference;
 import java.util.logging.Logger;
-import org.checkerframework.checker.nullness.compatqual.NullableDecl;
+import javax.annotation.CheckForNull;
+import org.checkerframework.checker.nullness.qual.Nullable;
 
 /**
  * A step in a pipeline of an asynchronous computation. When the last step in the computation is
@@ -190,10 +190,10 @@
  * @since 30.0
  */
 // TODO(dpb): Consider reusing one CloseableList for the entire pipeline, modulo combinations.
-@Beta // @Beta for one release.
 @DoNotMock("Use ClosingFuture.from(Futures.immediate*Future)")
+@ElementTypesAreNonnullByDefault
 // TODO(dpb): GWT compatibility.
-public final class ClosingFuture<V> {
+public final class ClosingFuture<V extends @Nullable Object> {
 
   private static final Logger logger = Logger.getLogger(ClosingFuture.class.getName());
 
@@ -232,10 +232,10 @@ public static final class DeferredCloser {
      * @return the first argument
      */
     @CanIgnoreReturnValue
-    @NullableDecl
+    @ParametricNullness
     // TODO(b/163345357): Widen bound to AutoCloseable once we require API Level 19.
-    public <C extends Object & Closeable> C eventuallyClose(
-        @NullableDecl C closeable, Executor closingExecutor) {
+    public <C extends @Nullable Object & @Nullable Closeable> C eventuallyClose(
+        @ParametricNullness C closeable, Executor closingExecutor) {
       checkNotNull(closingExecutor);
       if (closeable != null) {
         list.add(closeable, closingExecutor);
@@ -249,7 +249,7 @@ public <C extends Object & Closeable> C eventuallyClose(
    *
    * @param <V> the type of the result
    */
-  public interface ClosingCallable<V extends Object> {
+  public interface ClosingCallable<V extends @Nullable Object> {
     /**
      * Computes a result, or throws an exception if unable to do so.
      *
@@ -257,7 +257,7 @@ public interface ClosingCallable<V extends Object> {
      * closer.eventuallyClose()} will be closed when the {@link ClosingFuture} pipeline is done (but
      * not before this method completes), even if this method throws or the pipeline is cancelled.
      */
-    @NullableDecl
+    @ParametricNullness
     V call(DeferredCloser closer) throws Exception;
   }
 
@@ -267,7 +267,7 @@ public interface ClosingCallable<V extends Object> {
    * @param <V> the type of the result
    * @since 30.1
    */
-  public interface AsyncClosingCallable<V extends Object> {
+  public interface AsyncClosingCallable<V extends @Nullable Object> {
     /**
      * Computes a result, or throws an exception if unable to do so.
      *
@@ -284,7 +284,7 @@ public interface AsyncClosingCallable<V extends Object> {
    * @param <T> the type of the input to the function
    * @param <U> the type of the result of the function
    */
-  public interface ClosingFunction<T extends Object, U extends Object> {
+  public interface ClosingFunction<T extends @Nullable Object, U extends @Nullable Object> {
 
     /**
      * Applies this function to an input, or throws an exception if unable to do so.
@@ -293,8 +293,8 @@ public interface ClosingFunction<T extends Object, U extends Object> {
      * closer.eventuallyClose()} will be closed when the {@link ClosingFuture} pipeline is done (but
      * not before this method completes), even if this method throws or the pipeline is cancelled.
      */
-    @NullableDecl
-    U apply(DeferredCloser closer, @NullableDecl T input) throws Exception;
+    @ParametricNullness
+    U apply(DeferredCloser closer, @ParametricNullness T input) throws Exception;
   }
 
   /**
@@ -303,7 +303,7 @@ public interface ClosingFunction<T extends Object, U extends Object> {
    * @param <T> the type of the input to the function
    * @param <U> the type of the result of the function
    */
-  public interface AsyncClosingFunction<T extends Object, U extends Object> {
+  public interface AsyncClosingFunction<T extends @Nullable Object, U extends @Nullable Object> {
     /**
      * Applies this function to an input, or throws an exception if unable to do so.
      *
@@ -311,7 +311,7 @@ public interface AsyncClosingFunction<T extends Object, U extends Object> {
      * closer.eventuallyClose()} will be closed when the {@link ClosingFuture} pipeline is done (but
      * not before this method completes), even if this method throws or the pipeline is cancelled.
      */
-    ClosingFuture<U> apply(DeferredCloser closer, @NullableDecl T input) throws Exception;
+    ClosingFuture<U> apply(DeferredCloser closer, @ParametricNullness T input) throws Exception;
   }
 
   /**
@@ -324,7 +324,7 @@ public interface AsyncClosingFunction<T extends Object, U extends Object> {
    * @param <V> the type of the value of a successful operation
    * @see ClosingFuture#finishToValueAndCloser(ValueAndCloserConsumer, Executor)
    */
-  public static final class ValueAndCloser<V> {
+  public static final class ValueAndCloser<V extends @Nullable Object> {
 
     private final ClosingFuture<? extends V> closingFuture;
 
@@ -342,7 +342,7 @@ public static final class ValueAndCloser<V> {
      * @throws CancellationException if the computation was cancelled
      * @throws ExecutionException if the computation threw an exception
      */
-    @NullableDecl
+    @ParametricNullness
     public V get() throws ExecutionException {
       return getDone(closingFuture.future);
     }
@@ -369,7 +369,7 @@ public void closeAsync() {
    * @param <V> the type of the final value of a successful pipeline
    * @see ClosingFuture#finishToValueAndCloser(ValueAndCloserConsumer, Executor)
    */
-  public interface ValueAndCloserConsumer<V> {
+  public interface ValueAndCloserConsumer<V extends @Nullable Object> {
 
     /** Accepts a {@link ValueAndCloser} for the last step in a {@link ClosingFuture} pipeline. */
     void accept(ValueAndCloser<V> valueAndCloser);
@@ -381,7 +381,8 @@ public interface ValueAndCloserConsumer<V> {
    * @throws java.util.concurrent.RejectedExecutionException if the task cannot be scheduled for
    *     execution
    */
-  public static <V> ClosingFuture<V> submit(ClosingCallable<V> callable, Executor executor) {
+  public static <V extends @Nullable Object> ClosingFuture<V> submit(
+      ClosingCallable<V> callable, Executor executor) {
     return new ClosingFuture<>(callable, executor);
   }
 
@@ -392,7 +393,7 @@ public static <V> ClosingFuture<V> submit(ClosingCallable<V> callable, Executor
    *     execution
    * @since 30.1
    */
-  public static <V> ClosingFuture<V> submitAsync(
+  public static <V extends @Nullable Object> ClosingFuture<V> submitAsync(
       AsyncClosingCallable<V> callable, Executor executor) {
     return new ClosingFuture<>(callable, executor);
   }
@@ -404,7 +405,7 @@ public static <V> ClosingFuture<V> submitAsync(
    * implements {@link Closeable}. In order to start a pipeline with a value that will be closed
    * when the pipeline is done, use {@link #submit(ClosingCallable, Executor)} instead.
    */
-  public static <V> ClosingFuture<V> from(ListenableFuture<V> future) {
+  public static <V extends @Nullable Object> ClosingFuture<V> from(ListenableFuture<V> future) {
     return new ClosingFuture<V>(future);
   }
 
@@ -431,15 +432,16 @@ public static <V> ClosingFuture<V> from(ListenableFuture<V> future) {
    */
   @Deprecated
   // TODO(b/163345357): Widen bound to AutoCloseable once we require API Level 19.
-  public static <C extends Object & Closeable> ClosingFuture<C> eventuallyClosing(
-      ListenableFuture<C> future, final Executor closingExecutor) {
+  public static <C extends @Nullable Object & @Nullable Closeable>
+      ClosingFuture<C> eventuallyClosing(
+          ListenableFuture<C> future, final Executor closingExecutor) {
     checkNotNull(closingExecutor);
     final ClosingFuture<C> closingFuture = new ClosingFuture<>(nonCancellationPropagating(future));
     Futures.addCallback(
         future,
-        new FutureCallback<Closeable>() {
+        new FutureCallback<@Nullable Closeable>() {
           @Override
-          public void onSuccess(@NullableDecl Closeable result) {
+          public void onSuccess(@CheckForNull Closeable result) {
             closingFuture.closeables.closer.eventuallyClose(result, closingExecutor);
           }
 
@@ -492,8 +494,8 @@ public static Combiner whenAllSucceed(Iterable<? extends ClosingFuture<?>> futur
    * @throws IllegalStateException if a {@code ClosingFuture} has already been derived from any of
    *     the arguments, or if any has already been {@linkplain #finishToFuture() finished}
    */
-  public static <V1, V2> Combiner2<V1, V2> whenAllSucceed(
-      ClosingFuture<V1> future1, ClosingFuture<V2> future2) {
+  public static <V1 extends @Nullable Object, V2 extends @Nullable Object>
+      Combiner2<V1, V2> whenAllSucceed(ClosingFuture<V1> future1, ClosingFuture<V2> future2) {
     return new Combiner2<>(future1, future2);
   }
 
@@ -507,8 +509,10 @@ public static <V1, V2> Combiner2<V1, V2> whenAllSucceed(
    * @throws IllegalStateException if a {@code ClosingFuture} has already been derived from any of
    *     the arguments, or if any has already been {@linkplain #finishToFuture() finished}
    */
-  public static <V1, V2, V3> Combiner3<V1, V2, V3> whenAllSucceed(
-      ClosingFuture<V1> future1, ClosingFuture<V2> future2, ClosingFuture<V3> future3) {
+  public static <
+          V1 extends @Nullable Object, V2 extends @Nullable Object, V3 extends @Nullable Object>
+      Combiner3<V1, V2, V3> whenAllSucceed(
+          ClosingFuture<V1> future1, ClosingFuture<V2> future2, ClosingFuture<V3> future3) {
     return new Combiner3<>(future1, future2, future3);
   }
 
@@ -522,11 +526,16 @@ public static <V1, V2, V3> Combiner3<V1, V2, V3> whenAllSucceed(
    * @throws IllegalStateException if a {@code ClosingFuture} has already been derived from any of
    *     the arguments, or if any has already been {@linkplain #finishToFuture() finished}
    */
-  public static <V1, V2, V3, V4> Combiner4<V1, V2, V3, V4> whenAllSucceed(
-      ClosingFuture<V1> future1,
-      ClosingFuture<V2> future2,
-      ClosingFuture<V3> future3,
-      ClosingFuture<V4> future4) {
+  public static <
+          V1 extends @Nullable Object,
+          V2 extends @Nullable Object,
+          V3 extends @Nullable Object,
+          V4 extends @Nullable Object>
+      Combiner4<V1, V2, V3, V4> whenAllSucceed(
+          ClosingFuture<V1> future1,
+          ClosingFuture<V2> future2,
+          ClosingFuture<V3> future3,
+          ClosingFuture<V4> future4) {
     return new Combiner4<>(future1, future2, future3, future4);
   }
 
@@ -540,12 +549,18 @@ public static <V1, V2, V3, V4> Combiner4<V1, V2, V3, V4> whenAllSucceed(
    * @throws IllegalStateException if a {@code ClosingFuture} has already been derived from any of
    *     the arguments, or if any has already been {@linkplain #finishToFuture() finished}
    */
-  public static <V1, V2, V3, V4, V5> Combiner5<V1, V2, V3, V4, V5> whenAllSucceed(
-      ClosingFuture<V1> future1,
-      ClosingFuture<V2> future2,
-      ClosingFuture<V3> future3,
-      ClosingFuture<V4> future4,
-      ClosingFuture<V5> future5) {
+  public static <
+          V1 extends @Nullable Object,
+          V2 extends @Nullable Object,
+          V3 extends @Nullable Object,
+          V4 extends @Nullable Object,
+          V5 extends @Nullable Object>
+      Combiner5<V1, V2, V3, V4, V5> whenAllSucceed(
+          ClosingFuture<V1> future1,
+          ClosingFuture<V2> future2,
+          ClosingFuture<V3> future3,
+          ClosingFuture<V4> future4,
+          ClosingFuture<V5> future5) {
     return new Combiner5<>(future1, future2, future3, future4, future5);
   }
 
@@ -583,6 +598,7 @@ private ClosingFuture(final ClosingCallable<V> callable, Executor executor) {
         TrustedListenableFutureTask.create(
             new Callable<V>() {
               @Override
+              @ParametricNullness
               public V call() throws Exception {
                 return callable.call(closeables.closer);
               }
@@ -670,7 +686,7 @@ public ListenableFuture<?> statusFuture() {
    *     one, or if this {@code ClosingFuture} has already been {@linkplain #finishToFuture()
    *     finished}
    */
-  public <U> ClosingFuture<U> transform(
+  public <U extends @Nullable Object> ClosingFuture<U> transform(
       final ClosingFunction<? super V, U> function, Executor executor) {
     checkNotNull(function);
     AsyncFunction<V, U> applyFunction =
@@ -764,7 +780,7 @@ public String toString() {
    *     one, or if this {@code ClosingFuture} has already been {@linkplain #finishToFuture()
    *     finished}
    */
-  public <U> ClosingFuture<U> transformAsync(
+  public <U extends @Nullable Object> ClosingFuture<U> transformAsync(
       final AsyncClosingFunction<? super V, U> function, Executor executor) {
     checkNotNull(function);
     AsyncFunction<V, U> applyFunction =
@@ -808,8 +824,8 @@ public String toString() {
    * @param function transforms the value of a {@code ClosingFuture} step to a {@link
    *     ListenableFuture} with the value of a derived step
    */
-  public static <V, U> AsyncClosingFunction<V, U> withoutCloser(
-      final AsyncFunction<V, U> function) {
+  public static <V extends @Nullable Object, U extends @Nullable Object>
+      AsyncClosingFunction<V, U> withoutCloser(final AsyncFunction<V, U> function) {
     checkNotNull(function);
     return new AsyncClosingFunction<V, U>() {
       @Override
@@ -1078,7 +1094,7 @@ public void run() {
         executor);
   }
 
-  private static <C, V extends C> void provideValueAndCloser(
+  private static <C extends @Nullable Object, V extends C> void provideValueAndCloser(
       ValueAndCloserConsumer<C> consumer, ClosingFuture<V> closingFuture) {
     consumer.accept(new ValueAndCloser<C>(closingFuture));
   }
@@ -1114,7 +1130,7 @@ private void close() {
     closeables.close();
   }
 
-  private <U> ClosingFuture<U> derive(FluentFuture<U> future) {
+  private <U extends @Nullable Object> ClosingFuture<U> derive(FluentFuture<U> future) {
     ClosingFuture<U> derived = new ClosingFuture<>(future);
     becomeSubsumedInto(derived.closeables);
     return derived;
@@ -1150,17 +1166,17 @@ private Peeker(ImmutableList<ClosingFuture<?>> futures) {
      *     CombiningCallable#call(DeferredCloser, Peeker)} or {@link
      *     AsyncCombiningCallable#call(DeferredCloser, Peeker)}
      */
-    @NullableDecl
-    public final <D extends Object> D getDone(ClosingFuture<D> closingFuture)
+    @ParametricNullness
+    public final <D extends @Nullable Object> D getDone(ClosingFuture<D> closingFuture)
         throws ExecutionException {
       checkState(beingCalled);
       checkArgument(futures.contains(closingFuture));
       return Futures.getDone(closingFuture.future);
     }
 
-    @NullableDecl
-    private <V extends Object> V call(CombiningCallable<V> combiner, CloseableList closeables)
-        throws Exception {
+    @ParametricNullness
+    private <V extends @Nullable Object> V call(
+        CombiningCallable<V> combiner, CloseableList closeables) throws Exception {
       beingCalled = true;
       CloseableList newCloseables = new CloseableList();
       try {
@@ -1171,7 +1187,7 @@ private <V extends Object> V call(CombiningCallable<V> combiner, CloseableList c
       }
     }
 
-    private <V extends Object> FluentFuture<V> callAsync(
+    private <V extends @Nullable Object> FluentFuture<V> callAsync(
         AsyncCombiningCallable<V> combiner, CloseableList closeables) throws Exception {
       beingCalled = true;
       CloseableList newCloseables = new CloseableList();
@@ -1221,7 +1237,7 @@ public static class Combiner {
      *
      * @param <V> the type of the result
      */
-    public interface CombiningCallable<V extends Object> {
+    public interface CombiningCallable<V extends @Nullable Object> {
       /**
        * Computes a result, or throws an exception if unable to do so.
        *
@@ -1232,7 +1248,7 @@ public interface CombiningCallable<V extends Object> {
        *
        * @param peeker used to get the value of any of the input futures
        */
-      @NullableDecl
+      @ParametricNullness
       V call(DeferredCloser closer, Peeker peeker) throws Exception;
     }
 
@@ -1241,7 +1257,7 @@ public interface CombiningCallable<V extends Object> {
      *
      * @param <V> the type of the result
      */
-    public interface AsyncCombiningCallable<V extends Object> {
+    public interface AsyncCombiningCallable<V extends @Nullable Object> {
       /**
        * Computes a {@link ClosingFuture} result, or throws an exception if unable to do so.
        *
@@ -1280,11 +1296,12 @@ private Combiner(boolean allMustSucceed, Iterable<? extends ClosingFuture<?>> in
      * <p>If the combiningCallable throws an {@code ExecutionException}, the cause of the thrown
      * {@code ExecutionException} will be extracted and used as the failure of the derived step.
      */
-    public <V> ClosingFuture<V> call(
+    public <V extends @Nullable Object> ClosingFuture<V> call(
         final CombiningCallable<V> combiningCallable, Executor executor) {
       Callable<V> callable =
           new Callable<V>() {
             @Override
+            @ParametricNullness
             public V call() throws Exception {
               return new Peeker(inputs).call(combiningCallable, closeables);
             }
@@ -1336,7 +1353,7 @@ public String toString() {
      * <p>The same warnings about doing heavyweight operations within {@link
      * ClosingFuture#transformAsync(AsyncClosingFunction, Executor)} apply here.
      */
-    public <V> ClosingFuture<V> callAsync(
+    public <V extends @Nullable Object> ClosingFuture<V> callAsync(
         final AsyncCombiningCallable<V> combiningCallable, Executor executor) {
       AsyncCallable<V> asyncCallable =
           new AsyncCallable<V>() {
@@ -1356,7 +1373,7 @@ public String toString() {
       return derived;
     }
 
-    private FutureCombiner<Object> futureCombiner() {
+    private FutureCombiner<@Nullable Object> futureCombiner() {
       return allMustSucceed
           ? Futures.whenAllSucceed(inputFutures())
           : Futures.whenAllComplete(inputFutures());
@@ -1383,7 +1400,8 @@ private ImmutableList<FluentFuture<?>> inputFutures() {
    * @param <V1> the type returned by the first future
    * @param <V2> the type returned by the second future
    */
-  public static final class Combiner2<V1 extends Object, V2 extends Object> extends Combiner {
+  public static final class Combiner2<V1 extends @Nullable Object, V2 extends @Nullable Object>
+      extends Combiner {
 
     /**
      * A function that returns a value when applied to the values of the two futures passed to
@@ -1393,7 +1411,8 @@ public static final class Combiner2<V1 extends Object, V2 extends Object> extend
      * @param <V2> the type returned by the second future
      * @param <U> the type returned by the function
      */
-    public interface ClosingFunction2<V1 extends Object, V2 extends Object, U extends Object> {
+    public interface ClosingFunction2<
+        V1 extends @Nullable Object, V2 extends @Nullable Object, U extends @Nullable Object> {
 
       /**
        * Applies this function to two inputs, or throws an exception if unable to do so.
@@ -1403,8 +1422,8 @@ public interface ClosingFunction2<V1 extends Object, V2 extends Object, U extend
        * is done (but not before this method completes), even if this method throws or the pipeline
        * is cancelled.
        */
-      @NullableDecl
-      U apply(DeferredCloser closer, @NullableDecl V1 value1, @NullableDecl V2 value2)
+      @ParametricNullness
+      U apply(DeferredCloser closer, @ParametricNullness V1 value1, @ParametricNullness V2 value2)
           throws Exception;
     }
 
@@ -1416,7 +1435,8 @@ U apply(DeferredCloser closer, @NullableDecl V1 value1, @NullableDecl V2 value2)
      * @param <V2> the type returned by the second future
      * @param <U> the type returned by the function
      */
-    public interface AsyncClosingFunction2<V1 extends Object, V2 extends Object, U extends Object> {
+    public interface AsyncClosingFunction2<
+        V1 extends @Nullable Object, V2 extends @Nullable Object, U extends @Nullable Object> {
 
       /**
        * Applies this function to two inputs, or throws an exception if unable to do so.
@@ -1427,7 +1447,8 @@ public interface AsyncClosingFunction2<V1 extends Object, V2 extends Object, U e
        * is cancelled.
        */
       ClosingFuture<U> apply(
-          DeferredCloser closer, @NullableDecl V1 value1, @NullableDecl V2 value2) throws Exception;
+          DeferredCloser closer, @ParametricNullness V1 value1, @ParametricNullness V2 value2)
+          throws Exception;
     }
 
     private final ClosingFuture<V1> future1;
@@ -1452,12 +1473,12 @@ private Combiner2(ClosingFuture<V1> future1, ClosingFuture<V2> future2) {
      * <p>If the function throws an {@code ExecutionException}, the cause of the thrown {@code
      * ExecutionException} will be extracted and used as the failure of the derived step.
      */
-    public <U extends Object> ClosingFuture<U> call(
+    public <U extends @Nullable Object> ClosingFuture<U> call(
         final ClosingFunction2<V1, V2, U> function, Executor executor) {
       return call(
           new CombiningCallable<U>() {
             @Override
-            @NullableDecl
+            @ParametricNullness
             public U call(DeferredCloser closer, Peeker peeker) throws Exception {
               return function.apply(closer, peeker.getDone(future1), peeker.getDone(future2));
             }
@@ -1506,7 +1527,7 @@ public String toString() {
      * <p>The same warnings about doing heavyweight operations within {@link
      * ClosingFuture#transformAsync(AsyncClosingFunction, Executor)} apply here.
      */
-    public <U extends Object> ClosingFuture<U> callAsync(
+    public <U extends @Nullable Object> ClosingFuture<U> callAsync(
         final AsyncClosingFunction2<V1, V2, U> function, Executor executor) {
       return callAsync(
           new AsyncCombiningCallable<U>() {
@@ -1533,7 +1554,8 @@ public String toString() {
    * @param <V2> the type returned by the second future
    * @param <V3> the type returned by the third future
    */
-  public static final class Combiner3<V1 extends Object, V2 extends Object, V3 extends Object>
+  public static final class Combiner3<
+          V1 extends @Nullable Object, V2 extends @Nullable Object, V3 extends @Nullable Object>
       extends Combiner {
     /**
      * A function that returns a value when applied to the values of the three futures passed to
@@ -1545,7 +1567,10 @@ public static final class Combiner3<V1 extends Object, V2 extends Object, V3 ext
      * @param <U> the type returned by the function
      */
     public interface ClosingFunction3<
-        V1 extends Object, V2 extends Object, V3 extends Object, U extends Object> {
+        V1 extends @Nullable Object,
+        V2 extends @Nullable Object,
+        V3 extends @Nullable Object,
+        U extends @Nullable Object> {
       /**
        * Applies this function to three inputs, or throws an exception if unable to do so.
        *
@@ -1554,12 +1579,12 @@ public interface ClosingFunction3<
        * is done (but not before this method completes), even if this method throws or the pipeline
        * is cancelled.
        */
-      @NullableDecl
+      @ParametricNullness
       U apply(
           DeferredCloser closer,
-          @NullableDecl V1 value1,
-          @NullableDecl V2 value2,
-          @NullableDecl V3 v3)
+          @ParametricNullness V1 value1,
+          @ParametricNullness V2 value2,
+          @ParametricNullness V3 value3)
           throws Exception;
     }
 
@@ -1573,7 +1598,10 @@ U apply(
      * @param <U> the type returned by the function
      */
     public interface AsyncClosingFunction3<
-        V1 extends Object, V2 extends Object, V3 extends Object, U extends Object> {
+        V1 extends @Nullable Object,
+        V2 extends @Nullable Object,
+        V3 extends @Nullable Object,
+        U extends @Nullable Object> {
       /**
        * Applies this function to three inputs, or throws an exception if unable to do so.
        *
@@ -1584,9 +1612,9 @@ public interface AsyncClosingFunction3<
        */
       ClosingFuture<U> apply(
           DeferredCloser closer,
-          @NullableDecl V1 value1,
-          @NullableDecl V2 value2,
-          @NullableDecl V3 value3)
+          @ParametricNullness V1 value1,
+          @ParametricNullness V2 value2,
+          @ParametricNullness V3 value3)
           throws Exception;
     }
 
@@ -1615,12 +1643,12 @@ private Combiner3(
      * <p>If the function throws an {@code ExecutionException}, the cause of the thrown {@code
      * ExecutionException} will be extracted and used as the failure of the derived step.
      */
-    public <U extends Object> ClosingFuture<U> call(
+    public <U extends @Nullable Object> ClosingFuture<U> call(
         final ClosingFunction3<V1, V2, V3, U> function, Executor executor) {
       return call(
           new CombiningCallable<U>() {
             @Override
-            @NullableDecl
+            @ParametricNullness
             public U call(DeferredCloser closer, Peeker peeker) throws Exception {
               return function.apply(
                   closer,
@@ -1673,7 +1701,7 @@ public String toString() {
      * <p>The same warnings about doing heavyweight operations within {@link
      * ClosingFuture#transformAsync(AsyncClosingFunction, Executor)} apply here.
      */
-    public <U extends Object> ClosingFuture<U> callAsync(
+    public <U extends @Nullable Object> ClosingFuture<U> callAsync(
         final AsyncClosingFunction3<V1, V2, V3, U> function, Executor executor) {
       return callAsync(
           new AsyncCombiningCallable<U>() {
@@ -1706,7 +1734,10 @@ public String toString() {
    * @param <V4> the type returned by the fourth future
    */
   public static final class Combiner4<
-          V1 extends Object, V2 extends Object, V3 extends Object, V4 extends Object>
+          V1 extends @Nullable Object,
+          V2 extends @Nullable Object,
+          V3 extends @Nullable Object,
+          V4 extends @Nullable Object>
       extends Combiner {
     /**
      * A function that returns a value when applied to the values of the four futures passed to
@@ -1719,11 +1750,11 @@ public static final class Combiner4<
      * @param <U> the type returned by the function
      */
     public interface ClosingFunction4<
-        V1 extends Object,
-        V2 extends Object,
-        V3 extends Object,
-        V4 extends Object,
-        U extends Object> {
+        V1 extends @Nullable Object,
+        V2 extends @Nullable Object,
+        V3 extends @Nullable Object,
+        V4 extends @Nullable Object,
+        U extends @Nullable Object> {
       /**
        * Applies this function to four inputs, or throws an exception if unable to do so.
        *
@@ -1732,13 +1763,13 @@ public interface ClosingFunction4<
        * is done (but not before this method completes), even if this method throws or the pipeline
        * is cancelled.
        */
-      @NullableDecl
+      @ParametricNullness
       U apply(
           DeferredCloser closer,
-          @NullableDecl V1 value1,
-          @NullableDecl V2 value2,
-          @NullableDecl V3 value3,
-          @NullableDecl V4 value4)
+          @ParametricNullness V1 value1,
+          @ParametricNullness V2 value2,
+          @ParametricNullness V3 value3,
+          @ParametricNullness V4 value4)
           throws Exception;
     }
 
@@ -1754,11 +1785,11 @@ U apply(
      * @param <U> the type returned by the function
      */
     public interface AsyncClosingFunction4<
-        V1 extends Object,
-        V2 extends Object,
-        V3 extends Object,
-        V4 extends Object,
-        U extends Object> {
+        V1 extends @Nullable Object,
+        V2 extends @Nullable Object,
+        V3 extends @Nullable Object,
+        V4 extends @Nullable Object,
+        U extends @Nullable Object> {
       /**
        * Applies this function to four inputs, or throws an exception if unable to do so.
        *
@@ -1769,10 +1800,10 @@ public interface AsyncClosingFunction4<
        */
       ClosingFuture<U> apply(
           DeferredCloser closer,
-          @NullableDecl V1 value1,
-          @NullableDecl V2 value2,
-          @NullableDecl V3 value3,
-          @NullableDecl V4 value4)
+          @ParametricNullness V1 value1,
+          @ParametricNullness V2 value2,
+          @ParametricNullness V3 value3,
+          @ParametricNullness V4 value4)
           throws Exception;
     }
 
@@ -1806,12 +1837,12 @@ private Combiner4(
      * <p>If the function throws an {@code ExecutionException}, the cause of the thrown {@code
      * ExecutionException} will be extracted and used as the failure of the derived step.
      */
-    public <U extends Object> ClosingFuture<U> call(
+    public <U extends @Nullable Object> ClosingFuture<U> call(
         final ClosingFunction4<V1, V2, V3, V4, U> function, Executor executor) {
       return call(
           new CombiningCallable<U>() {
             @Override
-            @NullableDecl
+            @ParametricNullness
             public U call(DeferredCloser closer, Peeker peeker) throws Exception {
               return function.apply(
                   closer,
@@ -1865,7 +1896,7 @@ public String toString() {
      * <p>The same warnings about doing heavyweight operations within {@link
      * ClosingFuture#transformAsync(AsyncClosingFunction, Executor)} apply here.
      */
-    public <U extends Object> ClosingFuture<U> callAsync(
+    public <U extends @Nullable Object> ClosingFuture<U> callAsync(
         final AsyncClosingFunction4<V1, V2, V3, V4, U> function, Executor executor) {
       return callAsync(
           new AsyncCombiningCallable<U>() {
@@ -1900,11 +1931,11 @@ public String toString() {
    * @param <V5> the type returned by the fifth future
    */
   public static final class Combiner5<
-          V1 extends Object,
-          V2 extends Object,
-          V3 extends Object,
-          V4 extends Object,
-          V5 extends Object>
+          V1 extends @Nullable Object,
+          V2 extends @Nullable Object,
+          V3 extends @Nullable Object,
+          V4 extends @Nullable Object,
+          V5 extends @Nullable Object>
       extends Combiner {
     /**
      * A function that returns a value when applied to the values of the five futures passed to
@@ -1919,12 +1950,12 @@ public static final class Combiner5<
      * @param <U> the type returned by the function
      */
     public interface ClosingFunction5<
-        V1 extends Object,
-        V2 extends Object,
-        V3 extends Object,
-        V4 extends Object,
-        V5 extends Object,
-        U extends Object> {
+        V1 extends @Nullable Object,
+        V2 extends @Nullable Object,
+        V3 extends @Nullable Object,
+        V4 extends @Nullable Object,
+        V5 extends @Nullable Object,
+        U extends @Nullable Object> {
       /**
        * Applies this function to five inputs, or throws an exception if unable to do so.
        *
@@ -1933,14 +1964,14 @@ public interface ClosingFunction5<
        * is done (but not before this method completes), even if this method throws or the pipeline
        * is cancelled.
        */
-      @NullableDecl
+      @ParametricNullness
       U apply(
           DeferredCloser closer,
-          @NullableDecl V1 value1,
-          @NullableDecl V2 value2,
-          @NullableDecl V3 value3,
-          @NullableDecl V4 value4,
-          @NullableDecl V5 value5)
+          @ParametricNullness V1 value1,
+          @ParametricNullness V2 value2,
+          @ParametricNullness V3 value3,
+          @ParametricNullness V4 value4,
+          @ParametricNullness V5 value5)
           throws Exception;
     }
 
@@ -1957,12 +1988,12 @@ U apply(
      * @param <U> the type returned by the function
      */
     public interface AsyncClosingFunction5<
-        V1 extends Object,
-        V2 extends Object,
-        V3 extends Object,
-        V4 extends Object,
-        V5 extends Object,
-        U extends Object> {
+        V1 extends @Nullable Object,
+        V2 extends @Nullable Object,
+        V3 extends @Nullable Object,
+        V4 extends @Nullable Object,
+        V5 extends @Nullable Object,
+        U extends @Nullable Object> {
       /**
        * Applies this function to five inputs, or throws an exception if unable to do so.
        *
@@ -1973,11 +2004,11 @@ public interface AsyncClosingFunction5<
        */
       ClosingFuture<U> apply(
           DeferredCloser closer,
-          @NullableDecl V1 value1,
-          @NullableDecl V2 value2,
-          @NullableDecl V3 value3,
-          @NullableDecl V4 value4,
-          @NullableDecl V5 value5)
+          @ParametricNullness V1 value1,
+          @ParametricNullness V2 value2,
+          @ParametricNullness V3 value3,
+          @ParametricNullness V4 value4,
+          @ParametricNullness V5 value5)
           throws Exception;
     }
 
@@ -2015,12 +2046,12 @@ private Combiner5(
      * <p>If the function throws an {@code ExecutionException}, the cause of the thrown {@code
      * ExecutionException} will be extracted and used as the failure of the derived step.
      */
-    public <U extends Object> ClosingFuture<U> call(
+    public <U extends @Nullable Object> ClosingFuture<U> call(
         final ClosingFunction5<V1, V2, V3, V4, V5, U> function, Executor executor) {
       return call(
           new CombiningCallable<U>() {
             @Override
-            @NullableDecl
+            @ParametricNullness
             public U call(DeferredCloser closer, Peeker peeker) throws Exception {
               return function.apply(
                   closer,
@@ -2076,7 +2107,7 @@ public String toString() {
      * <p>The same warnings about doing heavyweight operations within {@link
      * ClosingFuture#transformAsync(AsyncClosingFunction, Executor)} apply here.
      */
-    public <U extends Object> ClosingFuture<U> callAsync(
+    public <U extends @Nullable Object> ClosingFuture<U> callAsync(
         final AsyncClosingFunction5<V1, V2, V3, V4, V5, U> function, Executor executor) {
       return callAsync(
           new AsyncCombiningCallable<U>() {
@@ -2114,7 +2145,7 @@ protected void finalize() {
     }
   }
 
-  private static void closeQuietly(final Closeable closeable, Executor executor) {
+  private static void closeQuietly(@CheckForNull final Closeable closeable, Executor executor) {
     if (closeable == null) {
       return;
     }
@@ -2156,10 +2187,12 @@ private static final class CloseableList extends IdentityHashMap<Closeable, Exec
       implements Closeable {
     private final DeferredCloser closer = new DeferredCloser(this);
     private volatile boolean closed;
-    private volatile CountDownLatch whenClosed;
+    @CheckForNull private volatile CountDownLatch whenClosed;
 
-    <V, U> ListenableFuture<U> applyClosingFunction(
-        ClosingFunction<? super V, U> transformation, V input) throws Exception {
+    <V extends @Nullable Object, U extends @Nullable Object>
+        ListenableFuture<U> applyClosingFunction(
+            ClosingFunction<? super V, U> transformation, @ParametricNullness V input)
+            throws Exception {
       // TODO(dpb): Consider ways to defer closing without creating a separate CloseableList.
       CloseableList newCloseables = new CloseableList();
       try {
@@ -2169,8 +2202,10 @@ <V, U> ListenableFuture<U> applyClosingFunction(
       }
     }
 
-    <V, U> FluentFuture<U> applyAsyncClosingFunction(
-        AsyncClosingFunction<V, U> transformation, V input) throws Exception {
+    <V extends @Nullable Object, U extends @Nullable Object>
+        FluentFuture<U> applyAsyncClosingFunction(
+            AsyncClosingFunction<V, U> transformation, @ParametricNullness V input)
+            throws Exception {
       // TODO(dpb): Consider ways to defer closing without creating a separate CloseableList.
       CloseableList newCloseables = new CloseableList();
       try {
@@ -2202,7 +2237,7 @@ public void close() {
       }
     }
 
-    void add(@NullableDecl Closeable closeable, Executor executor) {
+    void add(@CheckForNull Closeable closeable, Executor executor) {
       checkNotNull(executor);
       if (closeable == null) {
         return;
diff --git a/android/guava/src/com/google/common/util/concurrent/CollectionFuture.java b/android/guava/src/com/google/common/util/concurrent/CollectionFuture.java
index b6c752aaecff..c106c157e257 100644
--- a/android/guava/src/com/google/common/util/concurrent/CollectionFuture.java
+++ b/android/guava/src/com/google/common/util/concurrent/CollectionFuture.java
@@ -19,31 +19,34 @@
 
 import com.google.common.annotations.GwtCompatible;
 import com.google.common.collect.ImmutableCollection;
-import com.google.common.collect.ImmutableList;
 import com.google.common.collect.Lists;
+import java.util.Collections;
 import java.util.List;
-import org.checkerframework.checker.nullness.compatqual.NullableDecl;
+import javax.annotation.CheckForNull;
+import org.checkerframework.checker.nullness.qual.Nullable;
 
 /** Aggregate future that collects (stores) results of each future. */
 @GwtCompatible(emulated = true)
-abstract class CollectionFuture<V, C> extends AggregateFuture<V, C> {
+@ElementTypesAreNonnullByDefault
+abstract class CollectionFuture<V extends @Nullable Object, C extends @Nullable Object>
+    extends AggregateFuture<V, C> {
   /*
    * We access this field racily but safely. For discussion of a similar situation, see the comments
    * on the fields of TimeoutFuture. This field is slightly different than the fields discussed
    * there: cancel() never reads this field, only writes to it. That makes the race here completely
    * harmless, rather than just 99.99% harmless.
    */
-  private List<Present<V>> values;
+  @CheckForNull private List<@Nullable Present<V>> values;
 
   CollectionFuture(
       ImmutableCollection<? extends ListenableFuture<? extends V>> futures,
       boolean allMustSucceed) {
     super(futures, allMustSucceed, true);
 
-    List<Present<V>> values =
+    List<@Nullable Present<V>> values =
         futures.isEmpty()
-            ? ImmutableList.<Present<V>>of()
-            : Lists.<Present<V>>newArrayListWithCapacity(futures.size());
+            ? Collections.<@Nullable Present<V>>emptyList()
+            : Lists.<@Nullable Present<V>>newArrayListWithCapacity(futures.size());
 
     // Populate the results list with null initially.
     for (int i = 0; i < futures.size(); ++i) {
@@ -54,8 +57,8 @@ abstract class CollectionFuture<V, C> extends AggregateFuture<V, C> {
   }
 
   @Override
-  final void collectOneValue(int index, @NullableDecl V returnValue) {
-    List<Present<V>> localValues = values;
+  final void collectOneValue(int index, @ParametricNullness V returnValue) {
+    List<@Nullable Present<V>> localValues = values;
     if (localValues != null) {
       localValues.set(index, new Present<>(returnValue));
     }
@@ -63,7 +66,7 @@ final void collectOneValue(int index, @NullableDecl V returnValue) {
 
   @Override
   final void handleAllCompleted() {
-    List<Present<V>> localValues = values;
+    List<@Nullable Present<V>> localValues = values;
     if (localValues != null) {
       set(combine(localValues));
     }
@@ -75,10 +78,11 @@ void releaseResources(ReleaseResourcesReason reason) {
     this.values = null;
   }
 
-  abstract C combine(List<Present<V>> values);
+  abstract C combine(List<@Nullable Present<V>> values);
 
   /** Used for {@link Futures#allAsList} and {@link Futures#successfulAsList}. */
-  static final class ListFuture<V> extends CollectionFuture<V, List<V>> {
+  static final class ListFuture<V extends @Nullable Object>
+      extends CollectionFuture<V, List<@Nullable V>> {
     ListFuture(
         ImmutableCollection<? extends ListenableFuture<? extends V>> futures,
         boolean allMustSucceed) {
@@ -87,8 +91,8 @@ static final class ListFuture<V> extends CollectionFuture<V, List<V>> {
     }
 
     @Override
-    public List<V> combine(List<Present<V>> values) {
-      List<V> result = newArrayListWithCapacity(values.size());
+    public List<@Nullable V> combine(List<@Nullable Present<V>> values) {
+      List<@Nullable V> result = newArrayListWithCapacity(values.size());
       for (Present<V> element : values) {
         result.add(element != null ? element.value : null);
       }
@@ -97,7 +101,7 @@ public List<V> combine(List<Present<V>> values) {
   }
 
   /** The result of a successful {@code Future}. */
-  private static final class Present<V> {
+  private static final class Present<V extends @Nullable Object> {
     V value;
 
     Present(V value) {
diff --git a/android/guava/src/com/google/common/util/concurrent/CombinedFuture.java b/android/guava/src/com/google/common/util/concurrent/CombinedFuture.java
index 15a1c07d78af..c22211164c40 100644
--- a/android/guava/src/com/google/common/util/concurrent/CombinedFuture.java
+++ b/android/guava/src/com/google/common/util/concurrent/CombinedFuture.java
@@ -25,12 +25,15 @@
 import java.util.concurrent.ExecutionException;
 import java.util.concurrent.Executor;
 import java.util.concurrent.RejectedExecutionException;
-import org.checkerframework.checker.nullness.compatqual.NullableDecl;
+import javax.annotation.CheckForNull;
+import org.checkerframework.checker.nullness.qual.Nullable;
 
 /** Aggregate future that computes its value by calling a callable. */
 @GwtCompatible
-final class CombinedFuture<V> extends AggregateFuture<Object, V> {
-  private CombinedFutureInterruptibleTask<?> task;
+@ElementTypesAreNonnullByDefault
+final class CombinedFuture<V extends @Nullable Object>
+    extends AggregateFuture<@Nullable Object, V> {
+  @CheckForNull private CombinedFutureInterruptibleTask<?> task;
 
   CombinedFuture(
       ImmutableCollection<? extends ListenableFuture<?>> futures,
@@ -53,7 +56,7 @@ final class CombinedFuture<V> extends AggregateFuture<Object, V> {
   }
 
   @Override
-  void collectOneValue(int index, @NullableDecl Object returnValue) {}
+  void collectOneValue(int index, @CheckForNull Object returnValue) {}
 
   @Override
   void handleAllCompleted() {
@@ -87,7 +90,8 @@ protected void interruptTask() {
   }
 
   @WeakOuter
-  private abstract class CombinedFutureInterruptibleTask<T> extends InterruptibleTask<T> {
+  private abstract class CombinedFutureInterruptibleTask<T extends @Nullable Object>
+      extends InterruptibleTask<T> {
     private final Executor listenerExecutor;
 
     CombinedFutureInterruptibleTask(Executor listenerExecutor) {
@@ -108,7 +112,7 @@ final void execute() {
     }
 
     @Override
-    final void afterRanInterruptibly(T result, Throwable error) {
+    final void afterRanInterruptiblySuccess(@ParametricNullness T result) {
       /*
        * The future no longer needs to interrupt this task, so it no longer needs a reference to it.
        *
@@ -122,20 +126,28 @@ final void afterRanInterruptibly(T result, Throwable error) {
        */
       CombinedFuture.this.task = null;
 
-      if (error != null) {
-        if (error instanceof ExecutionException) {
-          CombinedFuture.this.setException(error.getCause());
-        } else if (error instanceof CancellationException) {
-          cancel(false);
-        } else {
-          CombinedFuture.this.setException(error);
-        }
+      setValue(result);
+    }
+
+    @Override
+    final void afterRanInterruptiblyFailure(Throwable error) {
+      // See afterRanInterruptiblySuccess.
+      CombinedFuture.this.task = null;
+
+      if (error instanceof ExecutionException) {
+        /*
+         * Cast to ExecutionException to satisfy our nullness checker, which (unsoundly but
+         * *usually* safely) assumes that getCause() returns non-null on an ExecutionException.
+         */
+        CombinedFuture.this.setException(((ExecutionException) error).getCause());
+      } else if (error instanceof CancellationException) {
+        cancel(false);
       } else {
-        setValue(result);
+        CombinedFuture.this.setException(error);
       }
     }
 
-    abstract void setValue(T value);
+    abstract void setValue(@ParametricNullness T value);
   }
 
   @WeakOuter
@@ -179,12 +191,13 @@ private final class CallableInterruptibleTask extends CombinedFutureInterruptibl
     }
 
     @Override
+    @ParametricNullness
     V runInterruptibly() throws Exception {
       return callable.call();
     }
 
     @Override
-    void setValue(V value) {
+    void setValue(@ParametricNullness V value) {
       CombinedFuture.this.set(value);
     }
 
diff --git a/android/guava/src/com/google/common/util/concurrent/CycleDetectingLockFactory.java b/android/guava/src/com/google/common/util/concurrent/CycleDetectingLockFactory.java
index d6ea486e3a26..decb5f1b183d 100644
--- a/android/guava/src/com/google/common/util/concurrent/CycleDetectingLockFactory.java
+++ b/android/guava/src/com/google/common/util/concurrent/CycleDetectingLockFactory.java
@@ -15,6 +15,7 @@
 package com.google.common.util.concurrent;
 
 import static com.google.common.base.Preconditions.checkNotNull;
+import static java.util.Objects.requireNonNull;
 
 import com.google.common.annotations.Beta;
 import com.google.common.annotations.GwtIncompatible;
@@ -42,7 +43,7 @@
 import java.util.concurrent.locks.ReentrantReadWriteLock;
 import java.util.logging.Level;
 import java.util.logging.Logger;
-import org.checkerframework.checker.nullness.compatqual.NullableDecl;
+import javax.annotation.CheckForNull;
 
 /**
  * The {@code CycleDetectingLockFactory} creates {@link ReentrantLock} instances and {@link
@@ -162,6 +163,7 @@
 @Beta
 @CanIgnoreReturnValue // TODO(cpovirk): Consider being more strict.
 @GwtIncompatible
+@ElementTypesAreNonnullByDefault
 public class CycleDetectingLockFactory {
 
   /**
@@ -268,7 +270,8 @@ public ReentrantReadWriteLock newReentrantReadWriteLock(String lockName, boolean
   }
 
   // A static mapping from an Enum type to its set of LockGraphNodes.
-  private static final ConcurrentMap<Class<? extends Enum>, Map<? extends Enum, LockGraphNode>>
+  private static final ConcurrentMap<
+          Class<? extends Enum<?>>, Map<? extends Enum<?>, LockGraphNode>>
       lockGraphNodesPerType = new MapMaker().weakKeys().makeMap();
 
   /** Creates a {@code CycleDetectingLockFactory.WithExplicitOrdering<E>}. */
@@ -280,16 +283,18 @@ public static <E extends Enum<E>> WithExplicitOrdering<E> newInstanceWithExplici
     checkNotNull(policy);
     @SuppressWarnings("unchecked")
     Map<E, LockGraphNode> lockGraphNodes = (Map<E, LockGraphNode>) getOrCreateNodes(enumClass);
-    return new WithExplicitOrdering<E>(policy, lockGraphNodes);
+    return new WithExplicitOrdering<>(policy, lockGraphNodes);
   }
 
-  private static Map<? extends Enum, LockGraphNode> getOrCreateNodes(Class<? extends Enum> clazz) {
-    Map<? extends Enum, LockGraphNode> existing = lockGraphNodesPerType.get(clazz);
+  @SuppressWarnings("unchecked")
+  private static <E extends Enum<E>> Map<? extends E, LockGraphNode> getOrCreateNodes(
+      Class<E> clazz) {
+    Map<E, LockGraphNode> existing = (Map<E, LockGraphNode>) lockGraphNodesPerType.get(clazz);
     if (existing != null) {
       return existing;
     }
-    Map<? extends Enum, LockGraphNode> created = createNodes(clazz);
-    existing = lockGraphNodesPerType.putIfAbsent(clazz, created);
+    Map<E, LockGraphNode> created = createNodes(clazz);
+    existing = (Map<E, LockGraphNode>) lockGraphNodesPerType.putIfAbsent(clazz, created);
     return MoreObjects.firstNonNull(existing, created);
   }
 
@@ -303,7 +308,7 @@ private static Map<? extends Enum, LockGraphNode> getOrCreateNodes(Class<? exten
   static <E extends Enum<E>> Map<E, LockGraphNode> createNodes(Class<E> clazz) {
     EnumMap<E, LockGraphNode> map = Maps.newEnumMap(clazz);
     E[] keys = clazz.getEnumConstants();
-    final int numKeys = keys.length;
+    int numKeys = keys.length;
     ArrayList<LockGraphNode> nodes = Lists.newArrayListWithCapacity(numKeys);
     // Create a LockGraphNode for each enum value.
     for (E key : keys) {
@@ -417,7 +422,9 @@ public ReentrantLock newReentrantLock(E rank) {
     public ReentrantLock newReentrantLock(E rank, boolean fair) {
       return policy == Policies.DISABLED
           ? new ReentrantLock(fair)
-          : new CycleDetectingReentrantLock(lockGraphNodes.get(rank), fair);
+          // requireNonNull is safe because createNodes inserts an entry for every E.
+          // (If the caller passes `null` for the `rank` parameter, this will throw, but that's OK.)
+          : new CycleDetectingReentrantLock(requireNonNull(lockGraphNodes.get(rank)), fair);
     }
 
     /** Equivalent to {@code newReentrantReadWriteLock(rank, false)}. */
@@ -436,7 +443,10 @@ public ReentrantReadWriteLock newReentrantReadWriteLock(E rank) {
     public ReentrantReadWriteLock newReentrantReadWriteLock(E rank, boolean fair) {
       return policy == Policies.DISABLED
           ? new ReentrantReadWriteLock(fair)
-          : new CycleDetectingReentrantReadWriteLock(lockGraphNodes.get(rank), fair);
+          // requireNonNull is safe because createNodes inserts an entry for every E.
+          // (If the caller passes `null` for the `rank` parameter, this will throw, but that's OK.)
+          : new CycleDetectingReentrantReadWriteLock(
+              requireNonNull(lockGraphNodes.get(rank)), fair);
     }
   }
 
@@ -546,7 +556,8 @@ public ExampleStackTrace getConflictingStackTrace() {
      */
     @Override
     public String getMessage() {
-      StringBuilder message = new StringBuilder(super.getMessage());
+      // requireNonNull is safe because ExampleStackTrace sets a non-null message.
+      StringBuilder message = new StringBuilder(requireNonNull(super.getMessage()));
       for (Throwable t = conflictingStackTrace; t != null; t = t.getCause()) {
         message.append(", ").append(t.getMessage());
       }
@@ -599,8 +610,8 @@ String getLockName() {
     }
 
     void checkAcquiredLocks(Policy policy, List<LockGraphNode> acquiredLocks) {
-      for (int i = 0, size = acquiredLocks.size(); i < size; i++) {
-        checkAcquiredLock(policy, acquiredLocks.get(i));
+      for (LockGraphNode acquiredLock : acquiredLocks) {
+        checkAcquiredLock(policy, acquiredLock);
       }
     }
 
@@ -674,7 +685,7 @@ void checkAcquiredLock(Policy policy, LockGraphNode acquiredLock) {
      * @return If a path was found, a chained {@link ExampleStackTrace} illustrating the path to the
      *     {@code lock}, or {@code null} if no path was found.
      */
-    @NullableDecl
+    @CheckForNull
     private ExampleStackTrace findPathTo(LockGraphNode node, Set<LockGraphNode> seen) {
       if (!seen.add(this)) {
         return null; // Already traversed this node.
diff --git a/android/guava/src/com/google/common/util/concurrent/DirectExecutor.java b/android/guava/src/com/google/common/util/concurrent/DirectExecutor.java
index 30229714c638..0c3a46b703c3 100644
--- a/android/guava/src/com/google/common/util/concurrent/DirectExecutor.java
+++ b/android/guava/src/com/google/common/util/concurrent/DirectExecutor.java
@@ -22,6 +22,7 @@
  * execute}.
  */
 @GwtCompatible
+@ElementTypesAreNonnullByDefault
 enum DirectExecutor implements Executor {
   INSTANCE;
 
diff --git a/android/guava/src/com/google/common/util/concurrent/ElementTypesAreNonnullByDefault.java b/android/guava/src/com/google/common/util/concurrent/ElementTypesAreNonnullByDefault.java
new file mode 100644
index 000000000000..34871255e812
--- /dev/null
+++ b/android/guava/src/com/google/common/util/concurrent/ElementTypesAreNonnullByDefault.java
@@ -0,0 +1,41 @@
+/*
+ * Copyright (C) 2021 The Guava Authors
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package com.google.common.util.concurrent;
+
+import static java.lang.annotation.ElementType.FIELD;
+import static java.lang.annotation.ElementType.METHOD;
+import static java.lang.annotation.ElementType.PARAMETER;
+import static java.lang.annotation.ElementType.TYPE;
+import static java.lang.annotation.RetentionPolicy.RUNTIME;
+
+import com.google.common.annotations.GwtCompatible;
+import java.lang.annotation.Retention;
+import java.lang.annotation.Target;
+import javax.annotation.Nonnull;
+import javax.annotation.meta.TypeQualifierDefault;
+
+/**
+ * Marks all "top-level" types as non-null in a way that is recognized by Kotlin. Note that this
+ * unfortunately includes type-variable usages, so we also provide {@link ParametricNullness} to
+ * "undo" it as best we can.
+ */
+@GwtCompatible
+@Retention(RUNTIME)
+@Target(TYPE)
+@TypeQualifierDefault({FIELD, METHOD, PARAMETER})
+@Nonnull
+@interface ElementTypesAreNonnullByDefault {}
diff --git a/android/guava/src/com/google/common/util/concurrent/ExecutionError.java b/android/guava/src/com/google/common/util/concurrent/ExecutionError.java
index dd25efb13de2..deaff15a426c 100644
--- a/android/guava/src/com/google/common/util/concurrent/ExecutionError.java
+++ b/android/guava/src/com/google/common/util/concurrent/ExecutionError.java
@@ -15,7 +15,7 @@
 package com.google.common.util.concurrent;
 
 import com.google.common.annotations.GwtCompatible;
-import org.checkerframework.checker.nullness.compatqual.NullableDecl;
+import javax.annotation.CheckForNull;
 
 /**
  * {@link Error} variant of {@link java.util.concurrent.ExecutionException}. As with {@code
@@ -28,22 +28,29 @@
  * @since 10.0
  */
 @GwtCompatible
+@ElementTypesAreNonnullByDefault
 public class ExecutionError extends Error {
+  /*
+   * Ideally, this class would have exposed only constructors that require a non-null cause. We
+   * might try to move in that direction, but there are complications. See
+   * https://github.com/jspecify/nullness-checker-for-checker-framework/blob/61aafa4ae52594830cfc2d61c8b113009dbdb045/src/main/java/com/google/jspecify/nullness/NullSpecTransfer.java#L789
+   */
+
   /** Creates a new instance with {@code null} as its detail message. */
   protected ExecutionError() {}
 
   /** Creates a new instance with the given detail message. */
-  protected ExecutionError(@NullableDecl String message) {
+  protected ExecutionError(@CheckForNull String message) {
     super(message);
   }
 
   /** Creates a new instance with the given detail message and cause. */
-  public ExecutionError(@NullableDecl String message, @NullableDecl Error cause) {
+  public ExecutionError(@CheckForNull String message, @CheckForNull Error cause) {
     super(message, cause);
   }
 
   /** Creates a new instance with the given cause. */
-  public ExecutionError(@NullableDecl Error cause) {
+  public ExecutionError(@CheckForNull Error cause) {
     super(cause);
   }
 
diff --git a/android/guava/src/com/google/common/util/concurrent/ExecutionList.java b/android/guava/src/com/google/common/util/concurrent/ExecutionList.java
index 153f42513794..96fc51ca88d0 100644
--- a/android/guava/src/com/google/common/util/concurrent/ExecutionList.java
+++ b/android/guava/src/com/google/common/util/concurrent/ExecutionList.java
@@ -21,7 +21,7 @@
 import java.util.concurrent.Executor;
 import java.util.logging.Level;
 import java.util.logging.Logger;
-import org.checkerframework.checker.nullness.compatqual.NullableDecl;
+import javax.annotation.CheckForNull;
 
 /**
  * A support class for {@code ListenableFuture} implementations to manage their listeners. An
@@ -40,6 +40,7 @@
  * @since 1.0
  */
 @GwtIncompatible
+@ElementTypesAreNonnullByDefault
 public final class ExecutionList {
   /** Logger to log exceptions caught when running runnables. */
   private static final Logger log = Logger.getLogger(ExecutionList.class.getName());
@@ -49,7 +50,7 @@ public final class ExecutionList {
    * RunnableExecutorPair#next} field.
    */
   @GuardedBy("this")
-  @NullableDecl
+  @CheckForNull
   private RunnableExecutorPair runnables;
 
   @GuardedBy("this")
@@ -154,9 +155,10 @@ private static void executeListener(Runnable runnable, Executor executor) {
   private static final class RunnableExecutorPair {
     final Runnable runnable;
     final Executor executor;
-    @NullableDecl RunnableExecutorPair next;
+    @CheckForNull RunnableExecutorPair next;
 
-    RunnableExecutorPair(Runnable runnable, Executor executor, RunnableExecutorPair next) {
+    RunnableExecutorPair(
+        Runnable runnable, Executor executor, @CheckForNull RunnableExecutorPair next) {
       this.runnable = runnable;
       this.executor = executor;
       this.next = next;
diff --git a/android/guava/src/com/google/common/util/concurrent/ExecutionSequencer.java b/android/guava/src/com/google/common/util/concurrent/ExecutionSequencer.java
index f589e08b0ac1..80c7779342b1 100644
--- a/android/guava/src/com/google/common/util/concurrent/ExecutionSequencer.java
+++ b/android/guava/src/com/google/common/util/concurrent/ExecutionSequencer.java
@@ -23,11 +23,13 @@
 import static com.google.common.util.concurrent.Futures.immediateFuture;
 import static com.google.common.util.concurrent.Futures.immediateVoidFuture;
 import static com.google.common.util.concurrent.MoreExecutors.directExecutor;
+import static java.util.Objects.requireNonNull;
 
-import com.google.common.annotations.Beta;
 import java.util.concurrent.Callable;
 import java.util.concurrent.Executor;
 import java.util.concurrent.atomic.AtomicReference;
+import javax.annotation.CheckForNull;
+import org.checkerframework.checker.nullness.qual.Nullable;
 
 /**
  * Serializes execution of tasks, somewhat like an "asynchronous {@code synchronized} block." Each
@@ -36,7 +38,14 @@
  * until the {@code Future} it returned is {@linkplain Future#isDone done} (successful, failed, or
  * cancelled).
  *
- * <p>This class has limited support for cancellation and other "early completion":
+ * <p>This class serializes execution of <i>submitted</i> tasks but not any <i>listeners</i> of
+ * those tasks.
+ *
+ * <p>Submitted tasks have a happens-before order as defined in the Java Language Specification.
+ * Tasks execute with the same happens-before order that the function calls to {@link #submit} and
+ * {@link #submitAsync} that submitted those tasks had.
+ *
+ * <p>This class has limited support for cancellation and other "early completions":
  *
  * <ul>
  *   <li>While calls to {@code submit} and {@code submitAsync} return a {@code Future} that can be
@@ -57,9 +66,6 @@
  *       safe for the next task to start.</i>
  * </ul>
  *
- * <p>An additional limitation: this class serializes execution of <i>tasks</i> but not any
- * <i>listeners</i> of those tasks.
- *
  * <p>This class is similar to {@link MoreExecutors#newSequentialExecutor}. This class is different
  * in a few ways:
  *
@@ -77,7 +83,7 @@
  *
  * @since 26.0
  */
-@Beta
+@ElementTypesAreNonnullByDefault
 public final class ExecutionSequencer {
 
   private ExecutionSequencer() {}
@@ -88,7 +94,7 @@ public static ExecutionSequencer create() {
   }
 
   /** This reference acts as a pointer tracking the head of a linked list of ListenableFutures. */
-  private final AtomicReference<ListenableFuture<Void>> ref =
+  private final AtomicReference<ListenableFuture<@Nullable Void>> ref =
       new AtomicReference<>(immediateVoidFuture());
 
   private ThreadConfinedTaskQueue latestTaskQueue = new ThreadConfinedTaskQueue();
@@ -122,11 +128,11 @@ private static final class ThreadConfinedTaskQueue {
      * All the states where thread != currentThread are identical for our purposes, and so even
      * though it's racy, we don't care which of those values we get, so no need to synchronize.
      */
-    Thread thread;
+    @CheckForNull Thread thread;
     /** Only used by the thread associated with this object */
-    Runnable nextTask;
+    @CheckForNull Runnable nextTask;
     /** Only used by the thread associated with this object */
-    Executor nextExecutor;
+    @CheckForNull Executor nextExecutor;
   }
 
   /**
@@ -136,7 +142,8 @@ private static final class ThreadConfinedTaskQueue {
    * execute, but if the output future is cancelled before {@link Callable#call()} is invoked,
    * {@link Callable#call()} will not be invoked.
    */
-  public <T> ListenableFuture<T> submit(final Callable<T> callable, Executor executor) {
+  public <T extends @Nullable Object> ListenableFuture<T> submit(
+      Callable<T> callable, Executor executor) {
     checkNotNull(callable);
     checkNotNull(executor);
     return submitAsync(
@@ -161,12 +168,12 @@ public String toString() {
    * callable} or a callable that has begun to execute, but if the output future is cancelled before
    * {@link AsyncCallable#call()} is invoked, {@link AsyncCallable#call()} will not be invoked.
    */
-  public <T> ListenableFuture<T> submitAsync(
-      final AsyncCallable<T> callable, final Executor executor) {
+  public <T extends @Nullable Object> ListenableFuture<T> submitAsync(
+      AsyncCallable<T> callable, Executor executor) {
     checkNotNull(callable);
     checkNotNull(executor);
-    final TaskNonReentrantExecutor taskExecutor = new TaskNonReentrantExecutor(executor, this);
-    final AsyncCallable<T> task =
+    TaskNonReentrantExecutor taskExecutor = new TaskNonReentrantExecutor(executor, this);
+    AsyncCallable<T> task =
         new AsyncCallable<T>() {
           @Override
           public ListenableFuture<T> call() throws Exception {
@@ -192,58 +199,55 @@ public String toString() {
      * have completed - namely after oldFuture is done, and taskFuture has either completed or been
      * cancelled before the callable started execution.
      */
-    final SettableFuture<Void> newFuture = SettableFuture.create();
+    SettableFuture<@Nullable Void> newFuture = SettableFuture.create();
 
-    final ListenableFuture<Void> oldFuture = ref.getAndSet(newFuture);
+    ListenableFuture<@Nullable Void> oldFuture = ref.getAndSet(newFuture);
 
     // Invoke our task once the previous future completes.
-    final TrustedListenableFutureTask<T> taskFuture = TrustedListenableFutureTask.create(task);
+    TrustedListenableFutureTask<T> taskFuture = TrustedListenableFutureTask.create(task);
     oldFuture.addListener(taskFuture, taskExecutor);
 
-    final ListenableFuture<T> outputFuture = Futures.nonCancellationPropagating(taskFuture);
+    ListenableFuture<T> outputFuture = Futures.nonCancellationPropagating(taskFuture);
 
     // newFuture's lifetime is determined by taskFuture, which can't complete before oldFuture
     // unless taskFuture is cancelled, in which case it falls back to oldFuture. This ensures that
     // if the future we return is cancelled, we don't begin execution of the next task until after
     // oldFuture completes.
     Runnable listener =
-        new Runnable() {
-          @Override
-          public void run() {
-            if (taskFuture.isDone()) {
-              // Since the value of oldFuture can only ever be immediateFuture(null) or setFuture of
-              // a future that eventually came from immediateFuture(null), this doesn't leak
-              // throwables or completion values.
-              newFuture.setFuture(oldFuture);
-            } else if (outputFuture.isCancelled() && taskExecutor.trySetCancelled()) {
-              // If this CAS succeeds, we know that the provided callable will never be invoked,
-              // so when oldFuture completes it is safe to allow the next submitted task to
-              // proceed. Doing this immediately here lets the next task run without waiting for
-              // the cancelled task's executor to run the noop AsyncCallable.
-              //
-              // ---
-              //
-              // If the CAS fails, the provided callable already started running (or it is about
-              // to). Our contract promises:
-              //
-              // 1. not to execute a new callable until the old one has returned
-              //
-              // If we were to cancel taskFuture, that would let the next task start while the old
-              // one is still running.
-              //
-              // Now, maybe we could tweak our implementation to not start the next task until the
-              // callable actually completes. (We could detect completion in our wrapper
-              // `AsyncCallable task`.) However, our contract also promises:
-              //
-              // 2. not to cancel any Future the user returned from an AsyncCallable
-              //
-              // We promise this because, once we cancel that Future, we would no longer be able to
-              // tell when any underlying work it is doing is done. Thus, we might start a new task
-              // while that underlying work is still running.
-              //
-              // So that is why we cancel only in the case of CAS success.
-              taskFuture.cancel(false);
-            }
+        () -> {
+          if (taskFuture.isDone()) {
+            // Since the value of oldFuture can only ever be immediateFuture(null) or setFuture of
+            // a future that eventually came from immediateFuture(null), this doesn't leak
+            // throwables or completion values.
+            newFuture.setFuture(oldFuture);
+          } else if (outputFuture.isCancelled() && taskExecutor.trySetCancelled()) {
+            // If this CAS succeeds, we know that the provided callable will never be invoked,
+            // so when oldFuture completes it is safe to allow the next submitted task to
+            // proceed. Doing this immediately here lets the next task run without waiting for
+            // the cancelled task's executor to run the noop AsyncCallable.
+            //
+            // ---
+            //
+            // If the CAS fails, the provided callable already started running (or it is about
+            // to). Our contract promises:
+            //
+            // 1. not to execute a new callable until the old one has returned
+            //
+            // If we were to cancel taskFuture, that would let the next task start while the old
+            // one is still running.
+            //
+            // Now, maybe we could tweak our implementation to not start the next task until the
+            // callable actually completes. (We could detect completion in our wrapper
+            // `AsyncCallable task`.) However, our contract also promises:
+            //
+            // 2. not to cancel any Future the user returned from an AsyncCallable
+            //
+            // We promise this because, once we cancel that Future, we would no longer be able to
+            // tell when any underlying work it is doing is done. Thus, we might start a new task
+            // while that underlying work is still running.
+            //
+            // So that is why we cancel only in the case of CAS success.
+            taskFuture.cancel(false);
           }
         };
     // Adding the listener to both futures guarantees that newFuture will aways be set. Adding to
@@ -279,7 +283,6 @@ enum RunningState {
    * properties; for example, calling WeakReference.get() on Android will block during an
    * otherwise-concurrent GC cycle.
    */
-  @SuppressWarnings("ShouldNotSubclass") // Saving an allocation here is worth it
   private static final class TaskNonReentrantExecutor extends AtomicReference<RunningState>
       implements Executor, Runnable {
 
@@ -287,22 +290,22 @@ private static final class TaskNonReentrantExecutor extends AtomicReference<Runn
      * Used to update and read the latestTaskQueue field. Set to null once the runnable has been run
      * or queued.
      */
-    ExecutionSequencer sequencer;
+    @CheckForNull ExecutionSequencer sequencer;
 
     /**
      * Executor the task was set to run on. Set to null when the task has been queued, run, or
      * cancelled.
      */
-    Executor delegate;
+    @CheckForNull Executor delegate;
 
     /**
      * Set before calling delegate.execute(); set to null once run, so that it can be GCed; this
      * object may live on after, if submitAsync returns an incomplete future.
      */
-    Runnable task;
+    @CheckForNull Runnable task;
 
     /** Thread that called execute(). Set in execute, cleared when delegate.execute() returns. */
-    Thread submitting;
+    @CheckForNull Thread submitting;
 
     private TaskNonReentrantExecutor(Executor delegate, ExecutionSequencer sequencer) {
       super(NOT_RUN);
@@ -327,8 +330,18 @@ public void execute(Runnable task) {
         return;
       }
       submitting = Thread.currentThread();
+
       try {
-        ThreadConfinedTaskQueue submittingTaskQueue = sequencer.latestTaskQueue;
+        /*
+         * requireNonNull is safe because we don't null out `sequencer` except:
+         *
+         * - above, where we return (in which case we never get here)
+         *
+         * - in `run`, which can't run until this Runnable is submitted to an executor, which
+         *   doesn't happen until below. (And this Executor -- yes, the object is both a Runnable
+         *   and an Executor -- is used for only a single `execute` call.)
+         */
+        ThreadConfinedTaskQueue submittingTaskQueue = requireNonNull(sequencer).latestTaskQueue;
         if (submittingTaskQueue.thread == submitting) {
           sequencer = null;
           // Submit from inside a reentrant submit. We don't know if this one will be reentrant (and
@@ -337,10 +350,12 @@ public void execute(Runnable task) {
           // execution.
           checkState(submittingTaskQueue.nextTask == null);
           submittingTaskQueue.nextTask = task;
-          submittingTaskQueue.nextExecutor = delegate;
+          // requireNonNull(delegate) is safe for reasons similar to requireNonNull(sequencer).
+          submittingTaskQueue.nextExecutor = requireNonNull(delegate);
           delegate = null;
         } else {
-          Executor localDelegate = delegate;
+          // requireNonNull(delegate) is safe for reasons similar to requireNonNull(sequencer).
+          Executor localDelegate = requireNonNull(delegate);
           delegate = null;
           this.task = task;
           localDelegate.execute(this);
@@ -359,7 +374,11 @@ public void execute(Runnable task) {
     public void run() {
       Thread currentThread = Thread.currentThread();
       if (currentThread != submitting) {
-        Runnable localTask = task;
+        /*
+         * requireNonNull is safe because we set `task` before submitting this Runnable to an
+         * Executor, and we don't null it out until here.
+         */
+        Runnable localTask = requireNonNull(task);
         task = null;
         localTask.run();
         return;
@@ -369,6 +388,18 @@ public void run() {
       // latestTaskQueue, and queue rather than calling execute() directly.
       ThreadConfinedTaskQueue executingTaskQueue = new ThreadConfinedTaskQueue();
       executingTaskQueue.thread = currentThread;
+      /*
+       * requireNonNull is safe because we don't null out `sequencer` except:
+       *
+       * - after the requireNonNull call below. (And this object has its Runnable.run override
+       *   called only once, just as it has its Executor.execute override called only once.)
+       *
+       * - if we return immediately from `execute` (in which case we never get here)
+       *
+       * - in the "reentrant submit" case of `execute` (in which case we must have started running a
+       *   user task -- which means that we already got past this code (or else we exited early
+       *   above))
+       */
       // Unconditionally set; there is no risk of throwing away a queued task from another thread,
       // because in order for the current task to run on this executor the previous task must have
       // already started execution. Because each task on a TaskNonReentrantExecutor can only produce
@@ -378,10 +409,11 @@ public void run() {
       // otherwise have another task queued on to it. Note the exception to this, cancellation, is
       // specially handled in execute() - execute() calls triggered by cancellation are no-ops, and
       // thus don't count.
-      sequencer.latestTaskQueue = executingTaskQueue;
+      requireNonNull(sequencer).latestTaskQueue = executingTaskQueue;
       sequencer = null;
       try {
-        Runnable localTask = task;
+        // requireNonNull is safe, as discussed above.
+        Runnable localTask = requireNonNull(task);
         task = null;
         localTask.run();
         // Now check if our task attempted to reentrantly execute the next task.
@@ -389,7 +421,7 @@ public void run() {
         Executor queuedExecutor;
         // Intentionally using non-short-circuit operator
         while ((queuedTask = executingTaskQueue.nextTask) != null
-            & (queuedExecutor = executingTaskQueue.nextExecutor) != null) {
+            && (queuedExecutor = executingTaskQueue.nextExecutor) != null) {
           executingTaskQueue.nextTask = null;
           executingTaskQueue.nextExecutor = null;
           queuedExecutor.execute(queuedTask);
diff --git a/android/guava/src/com/google/common/util/concurrent/FakeTimeLimiter.java b/android/guava/src/com/google/common/util/concurrent/FakeTimeLimiter.java
index 9dad51be2c8b..ddc9440188f3 100644
--- a/android/guava/src/com/google/common/util/concurrent/FakeTimeLimiter.java
+++ b/android/guava/src/com/google/common/util/concurrent/FakeTimeLimiter.java
@@ -22,6 +22,7 @@
 import java.util.concurrent.Callable;
 import java.util.concurrent.ExecutionException;
 import java.util.concurrent.TimeUnit;
+import org.checkerframework.checker.nullness.qual.Nullable;
 
 /**
  * A TimeLimiter implementation which actually does not attempt to limit time at all. This may be
@@ -36,6 +37,7 @@
 @Beta
 @CanIgnoreReturnValue
 @GwtIncompatible
+@ElementTypesAreNonnullByDefault
 public final class FakeTimeLimiter implements TimeLimiter {
   @Override
   public <T> T newProxy(
@@ -47,8 +49,9 @@ public <T> T newProxy(
   }
 
   @Override
-  public <T> T callWithTimeout(Callable<T> callable, long timeoutDuration, TimeUnit timeoutUnit)
-      throws ExecutionException {
+  @ParametricNullness
+  public <T extends @Nullable Object> T callWithTimeout(
+      Callable<T> callable, long timeoutDuration, TimeUnit timeoutUnit) throws ExecutionException {
     checkNotNull(callable);
     checkNotNull(timeoutUnit);
     try {
@@ -67,7 +70,8 @@ public <T> T callWithTimeout(Callable<T> callable, long timeoutDuration, TimeUni
   }
 
   @Override
-  public <T> T callUninterruptiblyWithTimeout(
+  @ParametricNullness
+  public <T extends @Nullable Object> T callUninterruptiblyWithTimeout(
       Callable<T> callable, long timeoutDuration, TimeUnit timeoutUnit) throws ExecutionException {
     return callWithTimeout(callable, timeoutDuration, timeoutUnit);
   }
diff --git a/android/guava/src/com/google/common/util/concurrent/FluentFuture.java b/android/guava/src/com/google/common/util/concurrent/FluentFuture.java
index 070cb157e849..683944c9e557 100644
--- a/android/guava/src/com/google/common/util/concurrent/FluentFuture.java
+++ b/android/guava/src/com/google/common/util/concurrent/FluentFuture.java
@@ -27,6 +27,7 @@
 import java.util.concurrent.ScheduledExecutorService;
 import java.util.concurrent.TimeUnit;
 import java.util.concurrent.TimeoutException;
+import org.checkerframework.checker.nullness.qual.Nullable;
 
 /**
  * A {@link ListenableFuture} that supports fluent chains of operations. For example:
@@ -69,25 +70,28 @@
  *
  * @since 23.0
  */
-@Beta
 @DoNotMock("Use FluentFuture.from(Futures.immediate*Future) or SettableFuture")
 @GwtCompatible(emulated = true)
-public abstract class FluentFuture<V> extends GwtFluentFutureCatchingSpecialization<V> {
+@ElementTypesAreNonnullByDefault
+public abstract class FluentFuture<V extends @Nullable Object>
+    extends GwtFluentFutureCatchingSpecialization<V> {
 
   /**
    * A less abstract subclass of AbstractFuture. This can be used to optimize setFuture by ensuring
    * that {@link #get} calls exactly the implementation of {@link AbstractFuture#get}.
    */
-  abstract static class TrustedFuture<V> extends FluentFuture<V>
+  abstract static class TrustedFuture<V extends @Nullable Object> extends FluentFuture<V>
       implements AbstractFuture.Trusted<V> {
     @CanIgnoreReturnValue
     @Override
+    @ParametricNullness
     public final V get() throws InterruptedException, ExecutionException {
       return super.get();
     }
 
     @CanIgnoreReturnValue
     @Override
+    @ParametricNullness
     public final V get(long timeout, TimeUnit unit)
         throws InterruptedException, ExecutionException, TimeoutException {
       return super.get(timeout, unit);
@@ -124,7 +128,7 @@ public final boolean cancel(boolean mayInterruptIfRunning) {
    * directly. If not, it is wrapped in a {@code FluentFuture} that delegates all calls to the
    * original {@code ListenableFuture}.
    */
-  public static <V> FluentFuture<V> from(ListenableFuture<V> future) {
+  public static <V extends @Nullable Object> FluentFuture<V> from(ListenableFuture<V> future) {
     return future instanceof FluentFuture
         ? (FluentFuture<V>) future
         : new ForwardingFluentFuture<V>(future);
@@ -137,7 +141,7 @@ public static <V> FluentFuture<V> from(ListenableFuture<V> future) {
    * @since 28.0
    */
   @Deprecated
-  public static <V> FluentFuture<V> from(FluentFuture<V> future) {
+  public static <V extends @Nullable Object> FluentFuture<V> from(FluentFuture<V> future) {
     return checkNotNull(future);
   }
 
@@ -179,6 +183,7 @@ public static <V> FluentFuture<V> from(FluentFuture<V> future) {
    * @param executor the executor that runs {@code fallback} if the input fails
    */
   @Partially.GwtIncompatible("AVAILABLE but requires exceptionType to be Throwable.class")
+  @Beta
   public final <X extends Throwable> FluentFuture<V> catching(
       Class<X> exceptionType, Function<? super X, ? extends V> fallback, Executor executor) {
     return (FluentFuture<V>) Futures.catching(this, exceptionType, fallback, executor);
@@ -243,6 +248,7 @@ public final <X extends Throwable> FluentFuture<V> catching(
    * @param executor the executor that runs {@code fallback} if the input fails
    */
   @Partially.GwtIncompatible("AVAILABLE but requires exceptionType to be Throwable.class")
+  @Beta
   public final <X extends Throwable> FluentFuture<V> catchingAsync(
       Class<X> exceptionType, AsyncFunction<? super X, ? extends V> fallback, Executor executor) {
     return (FluentFuture<V>) Futures.catchingAsync(this, exceptionType, fallback, executor);
@@ -260,6 +266,7 @@ public final <X extends Throwable> FluentFuture<V> catchingAsync(
    */
   @GwtIncompatible // ScheduledExecutorService
   @SuppressWarnings("GoodTime") // should accept a java.time.Duration
+  @Beta
   public final FluentFuture<V> withTimeout(
       long timeout, TimeUnit unit, ScheduledExecutorService scheduledExecutor) {
     return (FluentFuture<V>) Futures.withTimeout(this, timeout, unit, scheduledExecutor);
@@ -304,7 +311,8 @@ public final FluentFuture<V> withTimeout(
    * @return A future that holds result of the function (if the input succeeded) or the original
    *     input's failure (if not)
    */
-  public final <T> FluentFuture<T> transformAsync(
+  @Beta
+  public final <T extends @Nullable Object> FluentFuture<T> transformAsync(
       AsyncFunction<? super V, T> function, Executor executor) {
     return (FluentFuture<T>) Futures.transformAsync(this, function, executor);
   }
@@ -341,7 +349,9 @@ public final <T> FluentFuture<T> transformAsync(
    * @param executor Executor to run the function in.
    * @return A future that holds result of the transformation.
    */
-  public final <T> FluentFuture<T> transform(Function<? super V, T> function, Executor executor) {
+  @Beta
+  public final <T extends @Nullable Object> FluentFuture<T> transform(
+      Function<? super V, T> function, Executor executor) {
     return (FluentFuture<T>) Futures.transform(this, function, executor);
   }
 
diff --git a/android/guava/src/com/google/common/util/concurrent/ForwardingBlockingDeque.java b/android/guava/src/com/google/common/util/concurrent/ForwardingBlockingDeque.java
index 2485966948de..d0d72a815918 100644
--- a/android/guava/src/com/google/common/util/concurrent/ForwardingBlockingDeque.java
+++ b/android/guava/src/com/google/common/util/concurrent/ForwardingBlockingDeque.java
@@ -21,6 +21,7 @@
 import java.util.Collection;
 import java.util.concurrent.BlockingDeque;
 import java.util.concurrent.TimeUnit;
+import javax.annotation.CheckForNull;
 
 /**
  * A {@link BlockingDeque} which forwards all its method calls to another {@code BlockingDeque}.
@@ -44,6 +45,7 @@
  * @since 21.0 (since 14.0 as {@link com.google.common.collect.ForwardingBlockingDeque})
  */
 @GwtIncompatible
+@ElementTypesAreNonnullByDefault
 public abstract class ForwardingBlockingDeque<E> extends ForwardingDeque<E>
     implements BlockingDeque<E> {
 
@@ -89,11 +91,13 @@ public E takeLast() throws InterruptedException {
   }
 
   @Override
+  @CheckForNull
   public E pollFirst(long timeout, TimeUnit unit) throws InterruptedException {
     return delegate().pollFirst(timeout, unit);
   }
 
   @Override
+  @CheckForNull
   public E pollLast(long timeout, TimeUnit unit) throws InterruptedException {
     return delegate().pollLast(timeout, unit);
   }
@@ -114,6 +118,7 @@ public E take() throws InterruptedException {
   }
 
   @Override
+  @CheckForNull
   public E poll(long timeout, TimeUnit unit) throws InterruptedException {
     return delegate().poll(timeout, unit);
   }
diff --git a/android/guava/src/com/google/common/util/concurrent/ForwardingBlockingQueue.java b/android/guava/src/com/google/common/util/concurrent/ForwardingBlockingQueue.java
index f5575a15767c..dc8511d94c7c 100644
--- a/android/guava/src/com/google/common/util/concurrent/ForwardingBlockingQueue.java
+++ b/android/guava/src/com/google/common/util/concurrent/ForwardingBlockingQueue.java
@@ -20,6 +20,7 @@
 import java.util.Collection;
 import java.util.concurrent.BlockingQueue;
 import java.util.concurrent.TimeUnit;
+import javax.annotation.CheckForNull;
 
 /**
  * A {@link BlockingQueue} which forwards all its method calls to another {@link BlockingQueue}.
@@ -37,6 +38,7 @@
  */
 @CanIgnoreReturnValue // TODO(cpovirk): Consider being more strict.
 @GwtIncompatible
+@ElementTypesAreNonnullByDefault
 public abstract class ForwardingBlockingQueue<E> extends ForwardingQueue<E>
     implements BlockingQueue<E> {
 
@@ -62,6 +64,7 @@ public boolean offer(E e, long timeout, TimeUnit unit) throws InterruptedExcepti
   }
 
   @Override
+  @CheckForNull
   public E poll(long timeout, TimeUnit unit) throws InterruptedException {
     return delegate().poll(timeout, unit);
   }
diff --git a/android/guava/src/com/google/common/util/concurrent/ForwardingCondition.java b/android/guava/src/com/google/common/util/concurrent/ForwardingCondition.java
index 62c4d4c37843..d17f98cf2aa1 100644
--- a/android/guava/src/com/google/common/util/concurrent/ForwardingCondition.java
+++ b/android/guava/src/com/google/common/util/concurrent/ForwardingCondition.java
@@ -19,6 +19,7 @@
 import java.util.concurrent.locks.Condition;
 
 /** Forwarding wrapper around a {@code Condition}. */
+@ElementTypesAreNonnullByDefault
 abstract class ForwardingCondition implements Condition {
   abstract Condition delegate();
 
diff --git a/android/guava/src/com/google/common/util/concurrent/ForwardingExecutorService.java b/android/guava/src/com/google/common/util/concurrent/ForwardingExecutorService.java
index f9da1d495631..ed78b8685694 100644
--- a/android/guava/src/com/google/common/util/concurrent/ForwardingExecutorService.java
+++ b/android/guava/src/com/google/common/util/concurrent/ForwardingExecutorService.java
@@ -25,6 +25,7 @@
 import java.util.concurrent.Future;
 import java.util.concurrent.TimeUnit;
 import java.util.concurrent.TimeoutException;
+import org.checkerframework.checker.nullness.qual.Nullable;
 
 /**
  * An executor service which forwards all its method calls to another executor service. Subclasses
@@ -36,6 +37,7 @@
  */
 @CanIgnoreReturnValue // TODO(cpovirk): Consider being more strict.
 @GwtIncompatible
+@ElementTypesAreNonnullByDefault
 public abstract class ForwardingExecutorService extends ForwardingObject
     implements ExecutorService {
   /** Constructor for use by subclasses. */
@@ -50,26 +52,27 @@ public boolean awaitTermination(long timeout, TimeUnit unit) throws InterruptedE
   }
 
   @Override
-  public <T> List<Future<T>> invokeAll(Collection<? extends Callable<T>> tasks)
-      throws InterruptedException {
+  public <T extends @Nullable Object> List<Future<T>> invokeAll(
+      Collection<? extends Callable<T>> tasks) throws InterruptedException {
     return delegate().invokeAll(tasks);
   }
 
   @Override
-  public <T> List<Future<T>> invokeAll(
+  public <T extends @Nullable Object> List<Future<T>> invokeAll(
       Collection<? extends Callable<T>> tasks, long timeout, TimeUnit unit)
       throws InterruptedException {
     return delegate().invokeAll(tasks, timeout, unit);
   }
 
   @Override
-  public <T> T invokeAny(Collection<? extends Callable<T>> tasks)
+  public <T extends @Nullable Object> T invokeAny(Collection<? extends Callable<T>> tasks)
       throws InterruptedException, ExecutionException {
     return delegate().invokeAny(tasks);
   }
 
   @Override
-  public <T> T invokeAny(Collection<? extends Callable<T>> tasks, long timeout, TimeUnit unit)
+  public <T extends @Nullable Object> T invokeAny(
+      Collection<? extends Callable<T>> tasks, long timeout, TimeUnit unit)
       throws InterruptedException, ExecutionException, TimeoutException {
     return delegate().invokeAny(tasks, timeout, unit);
   }
@@ -100,7 +103,7 @@ public void execute(Runnable command) {
   }
 
   @Override
-  public <T> Future<T> submit(Callable<T> task) {
+  public <T extends @Nullable Object> Future<T> submit(Callable<T> task) {
     return delegate().submit(task);
   }
 
@@ -110,7 +113,8 @@ public Future<?> submit(Runnable task) {
   }
 
   @Override
-  public <T> Future<T> submit(Runnable task, T result) {
+  public <T extends @Nullable Object> Future<T> submit(
+      Runnable task, @ParametricNullness T result) {
     return delegate().submit(task, result);
   }
 }
diff --git a/android/guava/src/com/google/common/util/concurrent/ForwardingFluentFuture.java b/android/guava/src/com/google/common/util/concurrent/ForwardingFluentFuture.java
index 984fd680162d..cb779c34ed4b 100644
--- a/android/guava/src/com/google/common/util/concurrent/ForwardingFluentFuture.java
+++ b/android/guava/src/com/google/common/util/concurrent/ForwardingFluentFuture.java
@@ -21,6 +21,7 @@
 import java.util.concurrent.Executor;
 import java.util.concurrent.TimeUnit;
 import java.util.concurrent.TimeoutException;
+import org.checkerframework.checker.nullness.qual.Nullable;
 
 /**
  * {@link FluentFuture} that forwards all calls to a delegate.
@@ -33,7 +34,8 @@
  * forwards to that future and adds the desired methods.
  */
 @GwtCompatible
-final class ForwardingFluentFuture<V> extends FluentFuture<V> {
+@ElementTypesAreNonnullByDefault
+final class ForwardingFluentFuture<V extends @Nullable Object> extends FluentFuture<V> {
   private final ListenableFuture<V> delegate;
 
   ForwardingFluentFuture(ListenableFuture<V> delegate) {
@@ -61,11 +63,13 @@ public boolean isDone() {
   }
 
   @Override
+  @ParametricNullness
   public V get() throws InterruptedException, ExecutionException {
     return delegate.get();
   }
 
   @Override
+  @ParametricNullness
   public V get(long timeout, TimeUnit unit)
       throws InterruptedException, ExecutionException, TimeoutException {
     return delegate.get(timeout, unit);
diff --git a/android/guava/src/com/google/common/util/concurrent/ForwardingFuture.java b/android/guava/src/com/google/common/util/concurrent/ForwardingFuture.java
index 165793bef25c..47002b03a31b 100644
--- a/android/guava/src/com/google/common/util/concurrent/ForwardingFuture.java
+++ b/android/guava/src/com/google/common/util/concurrent/ForwardingFuture.java
@@ -22,6 +22,7 @@
 import java.util.concurrent.Future;
 import java.util.concurrent.TimeUnit;
 import java.util.concurrent.TimeoutException;
+import org.checkerframework.checker.nullness.qual.Nullable;
 
 /**
  * A {@link Future} which forwards all its method calls to another future. Subclasses should
@@ -35,7 +36,9 @@
  */
 @CanIgnoreReturnValue // TODO(cpovirk): Consider being more strict.
 @GwtCompatible
-public abstract class ForwardingFuture<V> extends ForwardingObject implements Future<V> {
+@ElementTypesAreNonnullByDefault
+public abstract class ForwardingFuture<V extends @Nullable Object> extends ForwardingObject
+    implements Future<V> {
   /** Constructor for use by subclasses. */
   protected ForwardingFuture() {}
 
@@ -58,11 +61,13 @@ public boolean isDone() {
   }
 
   @Override
+  @ParametricNullness
   public V get() throws InterruptedException, ExecutionException {
     return delegate().get();
   }
 
   @Override
+  @ParametricNullness
   public V get(long timeout, TimeUnit unit)
       throws InterruptedException, ExecutionException, TimeoutException {
     return delegate().get(timeout, unit);
@@ -75,7 +80,8 @@ public V get(long timeout, TimeUnit unit)
    *
    * @since 9.0
    */
-  public abstract static class SimpleForwardingFuture<V> extends ForwardingFuture<V> {
+  public abstract static class SimpleForwardingFuture<V extends @Nullable Object>
+      extends ForwardingFuture<V> {
     private final Future<V> delegate;
 
     protected SimpleForwardingFuture(Future<V> delegate) {
diff --git a/android/guava/src/com/google/common/util/concurrent/ForwardingListenableFuture.java b/android/guava/src/com/google/common/util/concurrent/ForwardingListenableFuture.java
index d3ed3c28a89b..386809194b84 100644
--- a/android/guava/src/com/google/common/util/concurrent/ForwardingListenableFuture.java
+++ b/android/guava/src/com/google/common/util/concurrent/ForwardingListenableFuture.java
@@ -18,6 +18,7 @@
 import com.google.common.base.Preconditions;
 import com.google.errorprone.annotations.CanIgnoreReturnValue;
 import java.util.concurrent.Executor;
+import org.checkerframework.checker.nullness.qual.Nullable;
 
 /**
  * A {@link ListenableFuture} which forwards all its method calls to another future. Subclasses
@@ -31,8 +32,9 @@
  */
 @CanIgnoreReturnValue // TODO(cpovirk): Consider being more strict.
 @GwtCompatible
-public abstract class ForwardingListenableFuture<V> extends ForwardingFuture<V>
-    implements ListenableFuture<V> {
+@ElementTypesAreNonnullByDefault
+public abstract class ForwardingListenableFuture<V extends @Nullable Object>
+    extends ForwardingFuture<V> implements ListenableFuture<V> {
 
   /** Constructor for use by subclasses. */
   protected ForwardingListenableFuture() {}
@@ -52,7 +54,7 @@ public void addListener(Runnable listener, Executor exec) {
    *
    * @since 9.0
    */
-  public abstract static class SimpleForwardingListenableFuture<V>
+  public abstract static class SimpleForwardingListenableFuture<V extends @Nullable Object>
       extends ForwardingListenableFuture<V> {
     private final ListenableFuture<V> delegate;
 
diff --git a/android/guava/src/com/google/common/util/concurrent/ForwardingListeningExecutorService.java b/android/guava/src/com/google/common/util/concurrent/ForwardingListeningExecutorService.java
index 48a49b89d83c..fe25b867af4c 100644
--- a/android/guava/src/com/google/common/util/concurrent/ForwardingListeningExecutorService.java
+++ b/android/guava/src/com/google/common/util/concurrent/ForwardingListeningExecutorService.java
@@ -17,6 +17,7 @@
 import com.google.common.annotations.GwtIncompatible;
 import com.google.errorprone.annotations.CanIgnoreReturnValue;
 import java.util.concurrent.Callable;
+import org.checkerframework.checker.nullness.qual.Nullable;
 
 /**
  * A listening executor service which forwards all its method calls to another listening executor
@@ -29,6 +30,7 @@
  */
 @CanIgnoreReturnValue // TODO(cpovirk): Consider being more strict.
 @GwtIncompatible
+@ElementTypesAreNonnullByDefault
 public abstract class ForwardingListeningExecutorService extends ForwardingExecutorService
     implements ListeningExecutorService {
   /** Constructor for use by subclasses. */
@@ -38,7 +40,7 @@ protected ForwardingListeningExecutorService() {}
   protected abstract ListeningExecutorService delegate();
 
   @Override
-  public <T> ListenableFuture<T> submit(Callable<T> task) {
+  public <T extends @Nullable Object> ListenableFuture<T> submit(Callable<T> task) {
     return delegate().submit(task);
   }
 
@@ -48,7 +50,8 @@ public ListenableFuture<?> submit(Runnable task) {
   }
 
   @Override
-  public <T> ListenableFuture<T> submit(Runnable task, T result) {
+  public <T extends @Nullable Object> ListenableFuture<T> submit(
+      Runnable task, @ParametricNullness T result) {
     return delegate().submit(task, result);
   }
 }
diff --git a/android/guava/src/com/google/common/util/concurrent/ForwardingLock.java b/android/guava/src/com/google/common/util/concurrent/ForwardingLock.java
index 8c50787ba8b6..db2026ab414c 100644
--- a/android/guava/src/com/google/common/util/concurrent/ForwardingLock.java
+++ b/android/guava/src/com/google/common/util/concurrent/ForwardingLock.java
@@ -19,6 +19,7 @@
 import java.util.concurrent.locks.Lock;
 
 /** Forwarding wrapper around a {@code Lock}. */
+@ElementTypesAreNonnullByDefault
 abstract class ForwardingLock implements Lock {
   abstract Lock delegate();
 
diff --git a/android/guava/src/com/google/common/util/concurrent/FutureCallback.java b/android/guava/src/com/google/common/util/concurrent/FutureCallback.java
index a10f71bbabae..f5684e7c907a 100644
--- a/android/guava/src/com/google/common/util/concurrent/FutureCallback.java
+++ b/android/guava/src/com/google/common/util/concurrent/FutureCallback.java
@@ -17,7 +17,7 @@
 import com.google.common.annotations.GwtCompatible;
 import java.util.concurrent.ExecutionException;
 import java.util.concurrent.Future;
-import org.checkerframework.checker.nullness.compatqual.NullableDecl;
+import org.checkerframework.checker.nullness.qual.Nullable;
 
 /**
  * A callback for accepting the results of a {@link java.util.concurrent.Future} computation
@@ -29,9 +29,10 @@
  * @since 10.0
  */
 @GwtCompatible
-public interface FutureCallback<V> {
+@ElementTypesAreNonnullByDefault
+public interface FutureCallback<V extends @Nullable Object> {
   /** Invoked with the result of the {@code Future} computation when it is successful. */
-  void onSuccess(@NullableDecl V result);
+  void onSuccess(@ParametricNullness V result);
 
   /**
    * Invoked when a {@code Future} computation fails or is canceled.
diff --git a/android/guava/src/com/google/common/util/concurrent/Futures.java b/android/guava/src/com/google/common/util/concurrent/Futures.java
index fa385f536c48..6bd68b4b5c5a 100644
--- a/android/guava/src/com/google/common/util/concurrent/Futures.java
+++ b/android/guava/src/com/google/common/util/concurrent/Futures.java
@@ -18,6 +18,7 @@
 import static com.google.common.base.Preconditions.checkState;
 import static com.google.common.util.concurrent.MoreExecutors.directExecutor;
 import static com.google.common.util.concurrent.Uninterruptibles.getUninterruptibly;
+import static java.util.Objects.requireNonNull;
 
 import com.google.common.annotations.Beta;
 import com.google.common.annotations.GwtCompatible;
@@ -44,7 +45,8 @@
 import java.util.concurrent.TimeUnit;
 import java.util.concurrent.TimeoutException;
 import java.util.concurrent.atomic.AtomicInteger;
-import org.checkerframework.checker.nullness.compatqual.NullableDecl;
+import javax.annotation.CheckForNull;
+import org.checkerframework.checker.nullness.qual.Nullable;
 
 /**
  * Static utility methods pertaining to the {@link Future} interface.
@@ -71,6 +73,7 @@
  * @since 1.0
  */
 @GwtCompatible(emulated = true)
+@ElementTypesAreNonnullByDefault
 public final class Futures extends GwtFuturesCatchingSpecialization {
 
   // A note on memory visibility.
@@ -125,7 +128,8 @@ private Futures() {}
    * getters just return the value. This {@code Future} can't be canceled or timed out and its
    * {@code isDone()} method always returns {@code true}.
    */
-  public static <V> ListenableFuture<V> immediateFuture(@NullableDecl V value) {
+  public static <V extends @Nullable Object> ListenableFuture<V> immediateFuture(
+      @ParametricNullness V value) {
     if (value == null) {
       // This cast is safe because null is assignable to V for all V (i.e. it is bivariant)
       @SuppressWarnings("unchecked")
@@ -142,8 +146,8 @@ public static <V> ListenableFuture<V> immediateFuture(@NullableDecl V value) {
    * @since 29.0
    */
   @SuppressWarnings("unchecked")
-  public static ListenableFuture<Void> immediateVoidFuture() {
-    return (ListenableFuture<Void>) ImmediateFuture.NULL;
+  public static ListenableFuture<@Nullable Void> immediateVoidFuture() {
+    return (ListenableFuture<@Nullable Void>) ImmediateFuture.NULL;
   }
 
   /**
@@ -153,7 +157,8 @@ public static ListenableFuture<Void> immediateVoidFuture() {
    * returns {@code true}. Calling {@code get()} will immediately throw the provided {@code
    * Throwable} wrapped in an {@code ExecutionException}.
    */
-  public static <V> ListenableFuture<V> immediateFailedFuture(Throwable throwable) {
+  public static <V extends @Nullable Object> ListenableFuture<V> immediateFailedFuture(
+      Throwable throwable) {
     checkNotNull(throwable);
     return new ImmediateFailedFuture<V>(throwable);
   }
@@ -164,8 +169,12 @@ public static <V> ListenableFuture<V> immediateFailedFuture(Throwable throwable)
    *
    * @since 14.0
    */
-  public static <V> ListenableFuture<V> immediateCancelledFuture() {
-    return new ImmediateCancelledFuture<V>();
+  public static <V extends @Nullable Object> ListenableFuture<V> immediateCancelledFuture() {
+    ListenableFuture<Object> instance = ImmediateCancelledFuture.INSTANCE;
+    if (instance != null) {
+      return (ListenableFuture<V>) instance;
+    }
+    return new ImmediateCancelledFuture<>();
   }
 
   /**
@@ -174,8 +183,8 @@ public static <V> ListenableFuture<V> immediateCancelledFuture() {
    * @throws RejectedExecutionException if the task cannot be scheduled for execution
    * @since 28.2
    */
-  @Beta
-  public static <O> ListenableFuture<O> submit(Callable<O> callable, Executor executor) {
+  public static <O extends @Nullable Object> ListenableFuture<O> submit(
+      Callable<O> callable, Executor executor) {
     TrustedListenableFutureTask<O> task = TrustedListenableFutureTask.create(callable);
     executor.execute(task);
     return task;
@@ -188,9 +197,9 @@ public static <O> ListenableFuture<O> submit(Callable<O> callable, Executor exec
    * @throws RejectedExecutionException if the task cannot be scheduled for execution
    * @since 28.2
    */
-  @Beta
-  public static ListenableFuture<Void> submit(Runnable runnable, Executor executor) {
-    TrustedListenableFutureTask<Void> task = TrustedListenableFutureTask.create(runnable, null);
+  public static ListenableFuture<@Nullable Void> submit(Runnable runnable, Executor executor) {
+    TrustedListenableFutureTask<@Nullable Void> task =
+        TrustedListenableFutureTask.create(runnable, null);
     executor.execute(task);
     return task;
   }
@@ -201,8 +210,8 @@ public static ListenableFuture<Void> submit(Runnable runnable, Executor executor
    * @throws RejectedExecutionException if the task cannot be scheduled for execution
    * @since 23.0
    */
-  @Beta
-  public static <O> ListenableFuture<O> submitAsync(AsyncCallable<O> callable, Executor executor) {
+  public static <O extends @Nullable Object> ListenableFuture<O> submitAsync(
+      AsyncCallable<O> callable, Executor executor) {
     TrustedListenableFutureTask<O> task = TrustedListenableFutureTask.create(callable);
     executor.execute(task);
     return task;
@@ -214,10 +223,10 @@ public static <O> ListenableFuture<O> submitAsync(AsyncCallable<O> callable, Exe
    * @throws RejectedExecutionException if the task cannot be scheduled for execution
    * @since 23.0
    */
-  @Beta
   @GwtIncompatible // java.util.concurrent.ScheduledExecutorService
   @SuppressWarnings("GoodTime") // should accept a java.time.Duration
-  public static <O> ListenableFuture<O> scheduleAsync(
+  // TODO(cpovirk): Return ListenableScheduledFuture?
+  public static <O extends @Nullable Object> ListenableFuture<O> scheduleAsync(
       AsyncCallable<O> callable,
       long delay,
       TimeUnit timeUnit,
@@ -274,7 +283,7 @@ public void run() {
    */
   @Beta
   @Partially.GwtIncompatible("AVAILABLE but requires exceptionType to be Throwable.class")
-  public static <V, X extends Throwable> ListenableFuture<V> catching(
+  public static <V extends @Nullable Object, X extends Throwable> ListenableFuture<V> catching(
       ListenableFuture<? extends V> input,
       Class<X> exceptionType,
       Function<? super X, ? extends V> fallback,
@@ -339,7 +348,7 @@ public static <V, X extends Throwable> ListenableFuture<V> catching(
    */
   @Beta
   @Partially.GwtIncompatible("AVAILABLE but requires exceptionType to be Throwable.class")
-  public static <V, X extends Throwable> ListenableFuture<V> catchingAsync(
+  public static <V extends @Nullable Object, X extends Throwable> ListenableFuture<V> catchingAsync(
       ListenableFuture<? extends V> input,
       Class<X> exceptionType,
       AsyncFunction<? super X, ? extends V> fallback,
@@ -362,7 +371,7 @@ public static <V, X extends Throwable> ListenableFuture<V> catchingAsync(
   @Beta
   @GwtIncompatible // java.util.concurrent.ScheduledExecutorService
   @SuppressWarnings("GoodTime") // should accept a java.time.Duration
-  public static <V> ListenableFuture<V> withTimeout(
+  public static <V extends @Nullable Object> ListenableFuture<V> withTimeout(
       ListenableFuture<V> delegate,
       long time,
       TimeUnit unit,
@@ -406,10 +415,11 @@ public static <V> ListenableFuture<V> withTimeout(
    * @since 19.0 (in 11.0 as {@code transform})
    */
   @Beta
-  public static <I, O> ListenableFuture<O> transformAsync(
-      ListenableFuture<I> input,
-      AsyncFunction<? super I, ? extends O> function,
-      Executor executor) {
+  public static <I extends @Nullable Object, O extends @Nullable Object>
+      ListenableFuture<O> transformAsync(
+          ListenableFuture<I> input,
+          AsyncFunction<? super I, ? extends O> function,
+          Executor executor) {
     return AbstractTransformFuture.create(input, function, executor);
   }
 
@@ -443,8 +453,9 @@ public static <I, O> ListenableFuture<O> transformAsync(
    * @since 9.0 (in 2.0 as {@code compose})
    */
   @Beta
-  public static <I, O> ListenableFuture<O> transform(
-      ListenableFuture<I> input, Function<? super I, ? extends O> function, Executor executor) {
+  public static <I extends @Nullable Object, O extends @Nullable Object>
+      ListenableFuture<O> transform(
+          ListenableFuture<I> input, Function<? super I, ? extends O> function, Executor executor) {
     return AbstractTransformFuture.create(input, function, executor);
   }
 
@@ -470,7 +481,7 @@ public static <I, O> ListenableFuture<O> transform(
    */
   @Beta
   @GwtIncompatible // TODO
-  public static <I, O> Future<O> lazyTransform(
+  public static <I extends @Nullable Object, O extends @Nullable Object> Future<O> lazyTransform(
       final Future<I> input, final Function<? super I, ? extends O> function) {
     checkNotNull(input);
     checkNotNull(function);
@@ -530,8 +541,14 @@ private O applyTransformation(I input) throws ExecutionException {
    */
   @Beta
   @SafeVarargs
-  public static <V> ListenableFuture<List<V>> allAsList(ListenableFuture<? extends V>... futures) {
-    return new ListFuture<V>(ImmutableList.copyOf(futures), true);
+  public static <V extends @Nullable Object> ListenableFuture<List<V>> allAsList(
+      ListenableFuture<? extends V>... futures) {
+    ListenableFuture<List<@Nullable V>> nullable =
+        new ListFuture<V>(ImmutableList.copyOf(futures), true);
+    // allAsList ensures that it fills the output list with V instances.
+    @SuppressWarnings("nullness")
+    ListenableFuture<List<V>> nonNull = nullable;
+    return nonNull;
   }
 
   /**
@@ -551,9 +568,14 @@ public static <V> ListenableFuture<List<V>> allAsList(ListenableFuture<? extends
    * @since 10.0
    */
   @Beta
-  public static <V> ListenableFuture<List<V>> allAsList(
+  public static <V extends @Nullable Object> ListenableFuture<List<V>> allAsList(
       Iterable<? extends ListenableFuture<? extends V>> futures) {
-    return new ListFuture<V>(ImmutableList.copyOf(futures), true);
+    ListenableFuture<List<@Nullable V>> nullable =
+        new ListFuture<V>(ImmutableList.copyOf(futures), true);
+    // allAsList ensures that it fills the output list with V instances.
+    @SuppressWarnings("nullness")
+    ListenableFuture<List<V>> nonNull = nullable;
+    return nonNull;
   }
 
   /**
@@ -566,7 +588,8 @@ public static <V> ListenableFuture<List<V>> allAsList(
    */
   @Beta
   @SafeVarargs
-  public static <V> FutureCombiner<V> whenAllComplete(ListenableFuture<? extends V>... futures) {
+  public static <V extends @Nullable Object> FutureCombiner<V> whenAllComplete(
+      ListenableFuture<? extends V>... futures) {
     return new FutureCombiner<V>(false, ImmutableList.copyOf(futures));
   }
 
@@ -579,7 +602,7 @@ public static <V> FutureCombiner<V> whenAllComplete(ListenableFuture<? extends V
    * @since 20.0
    */
   @Beta
-  public static <V> FutureCombiner<V> whenAllComplete(
+  public static <V extends @Nullable Object> FutureCombiner<V> whenAllComplete(
       Iterable<? extends ListenableFuture<? extends V>> futures) {
     return new FutureCombiner<V>(false, ImmutableList.copyOf(futures));
   }
@@ -593,7 +616,8 @@ public static <V> FutureCombiner<V> whenAllComplete(
    */
   @Beta
   @SafeVarargs
-  public static <V> FutureCombiner<V> whenAllSucceed(ListenableFuture<? extends V>... futures) {
+  public static <V extends @Nullable Object> FutureCombiner<V> whenAllSucceed(
+      ListenableFuture<? extends V>... futures) {
     return new FutureCombiner<V>(true, ImmutableList.copyOf(futures));
   }
 
@@ -605,7 +629,7 @@ public static <V> FutureCombiner<V> whenAllSucceed(ListenableFuture<? extends V>
    * @since 20.0
    */
   @Beta
-  public static <V> FutureCombiner<V> whenAllSucceed(
+  public static <V extends @Nullable Object> FutureCombiner<V> whenAllSucceed(
       Iterable<? extends ListenableFuture<? extends V>> futures) {
     return new FutureCombiner<V>(true, ImmutableList.copyOf(futures));
   }
@@ -639,7 +663,7 @@ public static <V> FutureCombiner<V> whenAllSucceed(
   @Beta
   @CanIgnoreReturnValue // TODO(cpovirk): Consider removing, especially if we provide run(Runnable)
   @GwtCompatible
-  public static final class FutureCombiner<V> {
+  public static final class FutureCombiner<V extends @Nullable Object> {
     private final boolean allMustSucceed;
     private final ImmutableList<ListenableFuture<? extends V>> futures;
 
@@ -663,7 +687,8 @@ private FutureCombiner(
      *
      * <p>Canceling this future will attempt to cancel all the component futures.
      */
-    public <C> ListenableFuture<C> callAsync(AsyncCallable<C> combiner, Executor executor) {
+    public <C extends @Nullable Object> ListenableFuture<C> callAsync(
+        AsyncCallable<C> combiner, Executor executor) {
       return new CombinedFuture<C>(futures, allMustSucceed, executor, combiner);
     }
 
@@ -682,7 +707,8 @@ public <C> ListenableFuture<C> callAsync(AsyncCallable<C> combiner, Executor exe
      * <p>Canceling this future will attempt to cancel all the component futures.
      */
     @CanIgnoreReturnValue // TODO(cpovirk): Remove this
-    public <C> ListenableFuture<C> call(Callable<C> combiner, Executor executor) {
+    public <C extends @Nullable Object> ListenableFuture<C> call(
+        Callable<C> combiner, Executor executor) {
       return new CombinedFuture<C>(futures, allMustSucceed, executor, combiner);
     }
 
@@ -699,8 +725,9 @@ public <C> ListenableFuture<C> call(Callable<C> combiner, Executor executor) {
      */
     public ListenableFuture<?> run(final Runnable combiner, Executor executor) {
       return call(
-          new Callable<Void>() {
+          new Callable<@Nullable Void>() {
             @Override
+            @CheckForNull
             public Void call() throws Exception {
               combiner.run();
               return null;
@@ -717,8 +744,8 @@ public Void call() throws Exception {
    *
    * @since 15.0
    */
-  @Beta
-  public static <V> ListenableFuture<V> nonCancellationPropagating(ListenableFuture<V> future) {
+  public static <V extends @Nullable Object> ListenableFuture<V> nonCancellationPropagating(
+      ListenableFuture<V> future) {
     if (future.isDone()) {
       return future;
     }
@@ -728,9 +755,9 @@ public static <V> ListenableFuture<V> nonCancellationPropagating(ListenableFutur
   }
 
   /** A wrapped future that does not propagate cancellation to its delegate. */
-  private static final class NonCancellationPropagatingFuture<V>
+  private static final class NonCancellationPropagatingFuture<V extends @Nullable Object>
       extends AbstractFuture.TrustedFuture<V> implements Runnable {
-    private ListenableFuture<V> delegate;
+    @CheckForNull private ListenableFuture<V> delegate;
 
     NonCancellationPropagatingFuture(final ListenableFuture<V> delegate) {
       this.delegate = delegate;
@@ -747,6 +774,7 @@ public void run() {
     }
 
     @Override
+    @CheckForNull
     protected String pendingToString() {
       ListenableFuture<V> localDelegate = delegate;
       if (localDelegate != null) {
@@ -781,8 +809,20 @@ protected void afterDone() {
    */
   @Beta
   @SafeVarargs
-  public static <V> ListenableFuture<List<V>> successfulAsList(
+  public static <V extends @Nullable Object> ListenableFuture<List<@Nullable V>> successfulAsList(
       ListenableFuture<? extends V>... futures) {
+    /*
+     * Another way to express this signature would be to bound <V> by @NonNull and accept
+     * LF<? extends @Nullable V>. That might be better: There's currently no difference between the
+     * outputs users get when calling this with <Foo> and calling it with <@Nullable Foo>. The only
+     * difference is that calling it with <Foo> won't work when an input Future has a @Nullable
+     * type. So why even make that error possible by giving callers the choice?
+     *
+     * On the other hand, the current signature is consistent with the similar allAsList method. And
+     * eventually this method may go away entirely in favor of an API like
+     * whenAllComplete().collectSuccesses(). That API would have a signature more like the current
+     * one.
+     */
     return new ListFuture<V>(ImmutableList.copyOf(futures), false);
   }
 
@@ -805,7 +845,7 @@ public static <V> ListenableFuture<List<V>> successfulAsList(
    * @since 10.0
    */
   @Beta
-  public static <V> ListenableFuture<List<V>> successfulAsList(
+  public static <V extends @Nullable Object> ListenableFuture<List<@Nullable V>> successfulAsList(
       Iterable<? extends ListenableFuture<? extends V>> futures) {
     return new ListFuture<V>(ImmutableList.copyOf(futures), false);
   }
@@ -831,22 +871,12 @@ public static <V> ListenableFuture<List<V>> successfulAsList(
    *
    * @since 17.0
    */
-  @Beta
-  public static <T> ImmutableList<ListenableFuture<T>> inCompletionOrder(
+  public static <T extends @Nullable Object> ImmutableList<ListenableFuture<T>> inCompletionOrder(
       Iterable<? extends ListenableFuture<? extends T>> futures) {
-    // Can't use Iterables.toArray because it's not gwt compatible
-    final Collection<ListenableFuture<? extends T>> collection;
-    if (futures instanceof Collection) {
-      collection = (Collection<ListenableFuture<? extends T>>) futures;
-    } else {
-      collection = ImmutableList.copyOf(futures);
-    }
-    @SuppressWarnings("unchecked")
-    ListenableFuture<? extends T>[] copy =
-        (ListenableFuture<? extends T>[])
-            collection.toArray(new ListenableFuture[collection.size()]);
+    ListenableFuture<? extends T>[] copy = gwtCompatibleToArray(futures);
     final InCompletionOrderState<T> state = new InCompletionOrderState<>(copy);
-    ImmutableList.Builder<AbstractFuture<T>> delegatesBuilder = ImmutableList.builder();
+    ImmutableList.Builder<AbstractFuture<T>> delegatesBuilder =
+        ImmutableList.builderWithExpectedSize(copy.length);
     for (int i = 0; i < copy.length; i++) {
       delegatesBuilder.add(new InCompletionOrderFuture<T>(state));
     }
@@ -869,11 +899,25 @@ public void run() {
     return delegatesCast;
   }
 
+  /** Can't use Iterables.toArray because it's not gwt compatible */
+  @SuppressWarnings("unchecked")
+  private static <T extends @Nullable Object> ListenableFuture<? extends T>[] gwtCompatibleToArray(
+      Iterable<? extends ListenableFuture<? extends T>> futures) {
+    final Collection<ListenableFuture<? extends T>> collection;
+    if (futures instanceof Collection) {
+      collection = (Collection<ListenableFuture<? extends T>>) futures;
+    } else {
+      collection = ImmutableList.copyOf(futures);
+    }
+    return (ListenableFuture<? extends T>[]) collection.toArray(new ListenableFuture<?>[0]);
+  }
+
   // This can't be a TrustedFuture, because TrustedFuture has clever optimizations that
   // mean cancel won't be called if this Future is passed into setFuture, and then
   // cancelled.
-  private static final class InCompletionOrderFuture<T> extends AbstractFuture<T> {
-    private InCompletionOrderState<T> state;
+  private static final class InCompletionOrderFuture<T extends @Nullable Object>
+      extends AbstractFuture<T> {
+    @CheckForNull private InCompletionOrderState<T> state;
 
     private InCompletionOrderFuture(InCompletionOrderState<T> state) {
       this.state = state;
@@ -883,7 +927,15 @@ private InCompletionOrderFuture(InCompletionOrderState<T> state) {
     public boolean cancel(boolean interruptIfRunning) {
       InCompletionOrderState<T> localState = state;
       if (super.cancel(interruptIfRunning)) {
-        localState.recordOutputCancellation(interruptIfRunning);
+        /*
+         * requireNonNull is generally safe: If cancel succeeded, then this Future was still
+         * pending, so its `state` field hasn't been nulled out yet.
+         *
+         * OK, it's technically possible for this to fail in the presence of unsafe publishing, as
+         * discussed in the comments in TimeoutFuture. TODO(cpovirk): Maybe check for null before
+         * calling recordOutputCancellation?
+         */
+        requireNonNull(localState).recordOutputCancellation(interruptIfRunning);
         return true;
       }
       return false;
@@ -895,6 +947,7 @@ protected void afterDone() {
     }
 
     @Override
+    @CheckForNull
     protected String pendingToString() {
       InCompletionOrderState<T> localState = state;
       if (localState != null) {
@@ -910,14 +963,15 @@ protected String pendingToString() {
     }
   }
 
-  private static final class InCompletionOrderState<T> {
+  private static final class InCompletionOrderState<T extends @Nullable Object> {
     // A happens-before edge between the writes of these fields and their reads exists, because
     // in order to read these fields, the corresponding write to incompleteOutputCount must have
     // been read.
     private boolean wasCancelled = false;
     private boolean shouldInterrupt = true;
     private final AtomicInteger incompleteOutputCount;
-    private final ListenableFuture<? extends T>[] inputFutures;
+    // We set the elements of the array to null as they complete.
+    private final @Nullable ListenableFuture<? extends T>[] inputFutures;
     private volatile int delegateIndex = 0;
 
     private InCompletionOrderState(ListenableFuture<? extends T>[] inputFutures) {
@@ -937,7 +991,11 @@ private void recordOutputCancellation(boolean interruptIfRunning) {
 
     private void recordInputCompletion(
         ImmutableList<AbstractFuture<T>> delegates, int inputFutureIndex) {
-      ListenableFuture<? extends T> inputFuture = inputFutures[inputFutureIndex];
+      /*
+       * requireNonNull is safe because we accepted an Iterable of non-null Future instances, and we
+       * don't overwrite an element in the array until after reading it.
+       */
+      ListenableFuture<? extends T> inputFuture = requireNonNull(inputFutures[inputFutureIndex]);
       // Null out our reference to this future, so it can be GCed
       inputFutures[inputFutureIndex] = null;
       for (int i = delegateIndex; i < delegates.size(); i++) {
@@ -956,7 +1014,7 @@ private void recordInputCompletion(
 
     private void recordCompletion() {
       if (incompleteOutputCount.decrementAndGet() == 0 && wasCancelled) {
-        for (ListenableFuture<?> toCancel : inputFutures) {
+        for (ListenableFuture<? extends T> toCancel : inputFutures) {
           if (toCancel != null) {
             toCancel.cancel(shouldInterrupt);
           }
@@ -1006,7 +1064,7 @@ private void recordCompletion() {
    * @param executor The executor to run {@code callback} when the future completes.
    * @since 10.0
    */
-  public static <V> void addCallback(
+  public static <V extends @Nullable Object> void addCallback(
       final ListenableFuture<V> future,
       final FutureCallback<? super V> callback,
       Executor executor) {
@@ -1015,7 +1073,7 @@ public static <V> void addCallback(
   }
 
   /** See {@link #addCallback(ListenableFuture, FutureCallback, Executor)} for behavioral notes. */
-  private static final class CallbackListener<V> implements Runnable {
+  private static final class CallbackListener<V extends @Nullable Object> implements Runnable {
     final Future<V> future;
     final FutureCallback<? super V> callback;
 
@@ -1074,7 +1132,8 @@ public String toString() {
    */
   @CanIgnoreReturnValue
   // TODO(cpovirk): Consider calling getDone() in our own code.
-  public static <V> V getDone(Future<V> future) throws ExecutionException {
+  @ParametricNullness
+  public static <V extends @Nullable Object> V getDone(Future<V> future) throws ExecutionException {
     /*
      * We throw IllegalStateException, since the call could succeed later. Perhaps we "should" throw
      * IllegalArgumentException, since the call could succeed with a different argument. Those
@@ -1134,8 +1193,9 @@ public static <V> V getDone(Future<V> future) throws ExecutionException {
   @Beta
   @CanIgnoreReturnValue
   @GwtIncompatible // reflection
-  public static <V, X extends Exception> V getChecked(Future<V> future, Class<X> exceptionClass)
-      throws X {
+  @ParametricNullness
+  public static <V extends @Nullable Object, X extends Exception> V getChecked(
+      Future<V> future, Class<X> exceptionClass) throws X {
     return FuturesGetChecked.getChecked(future, exceptionClass);
   }
 
@@ -1186,7 +1246,8 @@ public static <V, X extends Exception> V getChecked(Future<V> future, Class<X> e
   @CanIgnoreReturnValue
   @GwtIncompatible // reflection
   @SuppressWarnings("GoodTime") // should accept a java.time.Duration
-  public static <V, X extends Exception> V getChecked(
+  @ParametricNullness
+  public static <V extends @Nullable Object, X extends Exception> V getChecked(
       Future<V> future, Class<X> exceptionClass, long timeout, TimeUnit unit) throws X {
     return FuturesGetChecked.getChecked(future, exceptionClass, timeout, unit);
   }
@@ -1226,7 +1287,8 @@ public static <V, X extends Exception> V getChecked(
    * @since 10.0
    */
   @CanIgnoreReturnValue
-  public static <V> V getUnchecked(Future<V> future) {
+  @ParametricNullness
+  public static <V extends @Nullable Object> V getUnchecked(Future<V> future) {
     checkNotNull(future);
     try {
       return getUninterruptibly(future);
@@ -1256,7 +1318,7 @@ private static void wrapAndThrowUnchecked(Throwable cause) {
    * the computation -- makes sense, and if we don't convert it, the user still has to write a
    * try-catch block.
    *
-   * If you think you would use this method, let us know. You might also also look into the
+   * If you think you would use this method, let us know. You might also look into the
    * Fork-Join framework: http://docs.oracle.com/javase/tutorial/essential/concurrency/forkjoin.html
    */
 }
diff --git a/android/guava/src/com/google/common/util/concurrent/FuturesGetChecked.java b/android/guava/src/com/google/common/util/concurrent/FuturesGetChecked.java
index a5e9d328250c..04564f3a0770 100644
--- a/android/guava/src/com/google/common/util/concurrent/FuturesGetChecked.java
+++ b/android/guava/src/com/google/common/util/concurrent/FuturesGetChecked.java
@@ -23,7 +23,6 @@
 import com.google.common.base.Function;
 import com.google.common.collect.Ordering;
 import com.google.errorprone.annotations.CanIgnoreReturnValue;
-import com.google.j2objc.annotations.J2ObjCIncompatible;
 import java.lang.ref.WeakReference;
 import java.lang.reflect.Constructor;
 import java.lang.reflect.InvocationTargetException;
@@ -35,20 +34,25 @@
 import java.util.concurrent.Future;
 import java.util.concurrent.TimeUnit;
 import java.util.concurrent.TimeoutException;
-import org.checkerframework.checker.nullness.compatqual.NullableDecl;
+import javax.annotation.CheckForNull;
+import org.checkerframework.checker.nullness.qual.Nullable;
 
 /** Static methods used to implement {@link Futures#getChecked(Future, Class)}. */
 @GwtIncompatible
+@ElementTypesAreNonnullByDefault
 final class FuturesGetChecked {
   @CanIgnoreReturnValue
-  static <V, X extends Exception> V getChecked(Future<V> future, Class<X> exceptionClass) throws X {
+  @ParametricNullness
+  static <V extends @Nullable Object, X extends Exception> V getChecked(
+      Future<V> future, Class<X> exceptionClass) throws X {
     return getChecked(bestGetCheckedTypeValidator(), future, exceptionClass);
   }
 
   /** Implementation of {@link Futures#getChecked(Future, Class)}. */
   @CanIgnoreReturnValue
   @VisibleForTesting
-  static <V, X extends Exception> V getChecked(
+  @ParametricNullness
+  static <V extends @Nullable Object, X extends Exception> V getChecked(
       GetCheckedTypeValidator validator, Future<V> future, Class<X> exceptionClass) throws X {
     validator.validateClass(exceptionClass);
     try {
@@ -64,7 +68,8 @@ static <V, X extends Exception> V getChecked(
 
   /** Implementation of {@link Futures#getChecked(Future, Class, long, TimeUnit)}. */
   @CanIgnoreReturnValue
-  static <V, X extends Exception> V getChecked(
+  @ParametricNullness
+  static <V extends @Nullable Object, X extends Exception> V getChecked(
       Future<V> future, Class<X> exceptionClass, long timeout, TimeUnit unit) throws X {
     // TODO(cpovirk): benchmark a version of this method that accepts a GetCheckedTypeValidator
     bestGetCheckedTypeValidator().validateClass(exceptionClass);
@@ -95,12 +100,6 @@ static GetCheckedTypeValidator weakSetValidator() {
     return GetCheckedTypeValidatorHolder.WeakSetValidator.INSTANCE;
   }
 
-  @J2ObjCIncompatible // ClassValue
-  @VisibleForTesting
-  static GetCheckedTypeValidator classValueValidator() {
-    return GetCheckedTypeValidatorHolder.ClassValueValidator.INSTANCE;
-  }
-
   /**
    * Provides a check of whether an exception type is valid for use with {@link
    * FuturesGetChecked#getChecked(Future, Class)}, possibly using caching.
@@ -109,35 +108,8 @@ static GetCheckedTypeValidator classValueValidator() {
    */
   @VisibleForTesting
   static class GetCheckedTypeValidatorHolder {
-    static final String CLASS_VALUE_VALIDATOR_NAME =
-        GetCheckedTypeValidatorHolder.class.getName() + "$ClassValueValidator";
-
     static final GetCheckedTypeValidator BEST_VALIDATOR = getBestValidator();
 
-    @IgnoreJRERequirement // getChecked falls back to another implementation if necessary
-    @J2ObjCIncompatible // ClassValue
-    enum ClassValueValidator implements GetCheckedTypeValidator {
-      INSTANCE;
-
-      /*
-       * Static final fields are presumed to be fastest, based on our experience with
-       * UnsignedBytesBenchmark. TODO(cpovirk): benchmark this
-       */
-      private static final ClassValue<Boolean> isValidClass =
-          new ClassValue<Boolean>() {
-            @Override
-            protected Boolean computeValue(Class<?> type) {
-              checkExceptionClassValidity(type.asSubclass(Exception.class));
-              return true;
-            }
-          };
-
-      @Override
-      public void validateClass(Class<? extends Exception> exceptionClass) {
-        isValidClass.get(exceptionClass); // throws if invalid; returns safely (and caches) if valid
-      }
-    }
-
     enum WeakSetValidator implements GetCheckedTypeValidator {
       INSTANCE;
 
@@ -184,12 +156,7 @@ public void validateClass(Class<? extends Exception> exceptionClass) {
      * unable to do so.
      */
     static GetCheckedTypeValidator getBestValidator() {
-      try {
-        Class<?> theClass = Class.forName(CLASS_VALUE_VALIDATOR_NAME);
-        return (GetCheckedTypeValidator) theClass.getEnumConstants()[0];
-      } catch (Throwable t) { // ensure we really catch *everything*
-        return weakSetValidator();
-      }
+      return weakSetValidator();
     }
   }
 
@@ -225,7 +192,7 @@ private static <X extends Exception> X newWithCause(Class<X> exceptionClass, Thr
     @SuppressWarnings({"unchecked", "rawtypes"})
     List<Constructor<X>> constructors = (List) Arrays.asList(exceptionClass.getConstructors());
     for (Constructor<X> constructor : preferringStrings(constructors)) {
-      @NullableDecl X instance = newFromConstructor(constructor, cause);
+      X instance = newFromConstructor(constructor, cause);
       if (instance != null) {
         if (instance.getCause() == null) {
           instance.initCause(cause);
@@ -256,7 +223,7 @@ public Boolean apply(Constructor<?> input) {
               })
           .reverse();
 
-  @NullableDecl
+  @CheckForNull
   private static <X> X newFromConstructor(Constructor<X> constructor, Throwable cause) {
     Class<?>[] paramTypes = constructor.getParameterTypes();
     Object[] params = new Object[paramTypes.length];
diff --git a/android/guava/src/com/google/common/util/concurrent/GwtFluentFutureCatchingSpecialization.java b/android/guava/src/com/google/common/util/concurrent/GwtFluentFutureCatchingSpecialization.java
index e8acf625af72..d29a673dd854 100644
--- a/android/guava/src/com/google/common/util/concurrent/GwtFluentFutureCatchingSpecialization.java
+++ b/android/guava/src/com/google/common/util/concurrent/GwtFluentFutureCatchingSpecialization.java
@@ -15,6 +15,7 @@
 package com.google.common.util.concurrent;
 
 import com.google.common.annotations.GwtCompatible;
+import org.checkerframework.checker.nullness.qual.Nullable;
 
 /**
  * Hidden superclass of {@link FluentFuture} that provides us a place to declare special GWT
@@ -22,7 +23,9 @@
  * FluentFuture.catching} family of methods. Those versions have slightly different signatures.
  */
 @GwtCompatible(emulated = true)
-abstract class GwtFluentFutureCatchingSpecialization<V> extends AbstractFuture<V> {
+@ElementTypesAreNonnullByDefault
+abstract class GwtFluentFutureCatchingSpecialization<V extends @Nullable Object>
+    extends AbstractFuture<V> {
   /*
    * This server copy of the class is empty. The corresponding GWT copy contains alternative
    * versions of catching() and catchingAsync() with slightly different signatures from the ones
diff --git a/android/guava/src/com/google/common/util/concurrent/GwtFuturesCatchingSpecialization.java b/android/guava/src/com/google/common/util/concurrent/GwtFuturesCatchingSpecialization.java
index 4626ce949349..95131cec33f6 100644
--- a/android/guava/src/com/google/common/util/concurrent/GwtFuturesCatchingSpecialization.java
+++ b/android/guava/src/com/google/common/util/concurrent/GwtFuturesCatchingSpecialization.java
@@ -23,6 +23,7 @@
  * different signatures.
  */
 @GwtCompatible(emulated = true)
+@ElementTypesAreNonnullByDefault
 abstract class GwtFuturesCatchingSpecialization {
   /*
    * This server copy of the class is empty. The corresponding GWT copy contains alternative
diff --git a/android/guava/src/com/google/common/util/concurrent/ImmediateFuture.java b/android/guava/src/com/google/common/util/concurrent/ImmediateFuture.java
index 89b168bba73b..8b1c17ae48be 100644
--- a/android/guava/src/com/google/common/util/concurrent/ImmediateFuture.java
+++ b/android/guava/src/com/google/common/util/concurrent/ImmediateFuture.java
@@ -23,19 +23,20 @@
 import java.util.concurrent.TimeUnit;
 import java.util.logging.Level;
 import java.util.logging.Logger;
-import org.checkerframework.checker.nullness.compatqual.NullableDecl;
+import org.checkerframework.checker.nullness.qual.Nullable;
 
 /** Implementation of {@link Futures#immediateFuture}. */
 @GwtCompatible
+@ElementTypesAreNonnullByDefault
 // TODO(cpovirk): Make this final (but that may break Mockito spy calls).
-class ImmediateFuture<V> implements ListenableFuture<V> {
-  static final ListenableFuture<?> NULL = new ImmediateFuture<>(null);
+class ImmediateFuture<V extends @Nullable Object> implements ListenableFuture<V> {
+  static final ListenableFuture<?> NULL = new ImmediateFuture<@Nullable Object>(null);
 
   private static final Logger log = Logger.getLogger(ImmediateFuture.class.getName());
 
-  @NullableDecl private final V value;
+  @ParametricNullness private final V value;
 
-  ImmediateFuture(@NullableDecl V value) {
+  ImmediateFuture(@ParametricNullness V value) {
     this.value = value;
   }
 
@@ -62,11 +63,13 @@ public boolean cancel(boolean mayInterruptIfRunning) {
 
   // TODO(lukes): Consider throwing InterruptedException when appropriate.
   @Override
+  @ParametricNullness
   public V get() {
     return value;
   }
 
   @Override
+  @ParametricNullness
   public V get(long timeout, TimeUnit unit) throws ExecutionException {
     checkNotNull(unit);
     return get();
@@ -88,13 +91,16 @@ public String toString() {
     return super.toString() + "[status=SUCCESS, result=[" + value + "]]";
   }
 
-  static final class ImmediateFailedFuture<V> extends TrustedFuture<V> {
+  static final class ImmediateFailedFuture<V extends @Nullable Object> extends TrustedFuture<V> {
     ImmediateFailedFuture(Throwable thrown) {
       setException(thrown);
     }
   }
 
-  static final class ImmediateCancelledFuture<V> extends TrustedFuture<V> {
+  static final class ImmediateCancelledFuture<V extends @Nullable Object> extends TrustedFuture<V> {
+    static final @Nullable ImmediateCancelledFuture<Object> INSTANCE =
+        AbstractFuture.GENERATE_CANCELLATION_CAUSES ? null : new ImmediateCancelledFuture<>();
+
     ImmediateCancelledFuture() {
       cancel(false);
     }
diff --git a/android/guava/src/com/google/common/util/concurrent/InterruptibleTask.java b/android/guava/src/com/google/common/util/concurrent/InterruptibleTask.java
index acebae4eb4a8..bcec007303bd 100644
--- a/android/guava/src/com/google/common/util/concurrent/InterruptibleTask.java
+++ b/android/guava/src/com/google/common/util/concurrent/InterruptibleTask.java
@@ -14,20 +14,26 @@
 
 package com.google.common.util.concurrent;
 
+import static com.google.common.util.concurrent.NullnessCasts.uncheckedCastNullableTToT;
+
 import com.google.common.annotations.GwtCompatible;
+import com.google.common.annotations.VisibleForTesting;
 import com.google.j2objc.annotations.ReflectionSupport;
 import java.util.concurrent.atomic.AtomicReference;
+import java.util.concurrent.locks.AbstractOwnableSynchronizer;
 import java.util.concurrent.locks.LockSupport;
-import org.checkerframework.checker.nullness.compatqual.NullableDecl;
+import org.checkerframework.checker.nullness.qual.Nullable;
 
 @GwtCompatible(emulated = true)
 @ReflectionSupport(value = ReflectionSupport.Level.FULL)
+@ElementTypesAreNonnullByDefault
 // Some Android 5.0.x Samsung devices have bugs in JDK reflection APIs that cause
 // getDeclaredField to throw a NoSuchFieldException when the field is definitely there.
 // Since this class only needs CAS on one field, we can avoid this bug by extending AtomicReference
 // instead of using an AtomicReferenceFieldUpdater. This reference stores Thread instances
 // and DONE/INTERRUPTED - they have a common ancestor of Runnable.
-abstract class InterruptibleTask<T> extends AtomicReference<Runnable> implements Runnable {
+abstract class InterruptibleTask<T extends @Nullable Object>
+    extends AtomicReference<@Nullable Runnable> implements Runnable {
   static {
     // Prevent rare disastrous classloading in first call to LockSupport.park.
     // See: https://bugs.openjdk.java.net/browse/JDK-8074773
@@ -42,7 +48,6 @@ public void run() {}
   // The thread executing the task publishes itself to the superclass' reference and the thread
   // interrupting sets DONE when it has finished interrupting.
   private static final Runnable DONE = new DoNothingRunnable();
-  private static final Runnable INTERRUPTING = new DoNothingRunnable();
   private static final Runnable PARKED = new DoNothingRunnable();
   // Why 1000?  WHY NOT!
   private static final int MAX_BUSY_WAIT_SPINS = 1000;
@@ -73,66 +78,83 @@ public final void run() {
     } finally {
       // Attempt to set the task as done so that further attempts to interrupt will fail.
       if (!compareAndSet(currentThread, DONE)) {
-        // If we were interrupted, it is possible that the interrupted bit hasn't been set yet. Wait
-        // for the interrupting thread to set DONE. See interruptTask().
-        // We want to wait so that we don't interrupt the _next_ thing run on the thread.
-        // Note: We don't reset the interrupted bit, just wait for it to be set.
-        // If this is a thread pool thread, the thread pool will reset it for us. Otherwise, the
-        // interrupted bit may have been intended for something else, so don't clear it.
-        boolean restoreInterruptedBit = false;
-        int spinCount = 0;
-        // Interrupting Cow Says:
-        //  ______
-        // < Spin >
-        //  ------
-        //        \   ^__^
-        //         \  (oo)\_______
-        //            (__)\       )\/\
-        //                ||----w |
-        //                ||     ||
-        Runnable state = get();
-        while (state == INTERRUPTING || state == PARKED) {
-          spinCount++;
-          if (spinCount > MAX_BUSY_WAIT_SPINS) {
-            // If we have spun a lot just park ourselves.
-            // This will save CPU while we wait for a slow interrupting thread.  In theory
-            // interruptTask() should be very fast but due to InterruptibleChannel and
-            // JavaLangAccess.blockedOn(Thread, Interruptible), it isn't predictable what work might
-            // be done.  (e.g. close a file and flush buffers to disk).  To protect ourselve from
-            // this we park ourselves and tell our interrupter that we did so.
-            if (state == PARKED || compareAndSet(INTERRUPTING, PARKED)) {
-              // Interrupting Cow Says:
-              //  ______
-              // < Park >
-              //  ------
-              //        \   ^__^
-              //         \  (oo)\_______
-              //            (__)\       )\/\
-              //                ||----w |
-              //                ||     ||
-              // We need to clear the interrupted bit prior to calling park and maintain it in case
-              // we wake up spuriously.
-              restoreInterruptedBit = Thread.interrupted() || restoreInterruptedBit;
-              LockSupport.park(this);
-            }
-          } else {
-            Thread.yield();
-          }
-          state = get();
-        }
-        if (restoreInterruptedBit) {
-          currentThread.interrupt();
+        waitForInterrupt(currentThread);
+      }
+      if (run) {
+        if (error == null) {
+          // The cast is safe because of the `run` and `error` checks.
+          afterRanInterruptiblySuccess(uncheckedCastNullableTToT(result));
+        } else {
+          afterRanInterruptiblyFailure(error);
         }
+      }
+    }
+  }
+
+  private void waitForInterrupt(Thread currentThread) {
+    /*
+     * If someone called cancel(true), it is possible that the interrupted bit hasn't been set yet.
+     * Wait for the interrupting thread to set DONE. (See interruptTask().) We want to wait so that
+     * the interrupting thread doesn't interrupt the _next_ thing to run on this thread.
+     *
+     * Note: We don't reset the interrupted bit, just wait for it to be set. If this is a thread
+     * pool thread, the thread pool will reset it for us. Otherwise, the interrupted bit may have
+     * been intended for something else, so don't clear it.
+     */
+    boolean restoreInterruptedBit = false;
+    int spinCount = 0;
+    // Interrupting Cow Says:
+    //  ______
+    // < Spin >
+    //  ------
+    //        \   ^__^
+    //         \  (oo)\_______
+    //            (__)\       )\/\
+    //                ||----w |
+    //                ||     ||
+    Runnable state = get();
+    Blocker blocker = null;
+    while (state instanceof Blocker || state == PARKED) {
+      if (state instanceof Blocker) {
+        blocker = (Blocker) state;
+      }
+      spinCount++;
+      if (spinCount > MAX_BUSY_WAIT_SPINS) {
         /*
-         * TODO(cpovirk): Clear interrupt status here? We currently don't, which means that an
-         * interrupt before, during, or after runInterruptibly() (unless it produced an
-         * InterruptedException caught above) can linger and affect listeners.
+         * If we have spun a lot, just park ourselves. This will save CPU while we wait for a slow
+         * interrupting thread. In theory, interruptTask() should be very fast, but due to
+         * InterruptibleChannel and JavaLangAccess.blockedOn(Thread, Interruptible), it isn't
+         * predictable what work might be done. (e.g., close a file and flush buffers to disk). To
+         * protect ourselves from this, we park ourselves and tell our interrupter that we did so.
          */
+        if (state == PARKED || compareAndSet(state, PARKED)) {
+          // Interrupting Cow Says:
+          //  ______
+          // < Park >
+          //  ------
+          //        \   ^__^
+          //         \  (oo)\_______
+          //            (__)\       )\/\
+          //                ||----w |
+          //                ||     ||
+          // We need to clear the interrupted bit prior to calling park and maintain it in case we
+          // wake up spuriously.
+          restoreInterruptedBit = Thread.interrupted() || restoreInterruptedBit;
+          LockSupport.park(blocker);
+        }
+      } else {
+        Thread.yield();
       }
-      if (run) {
-        afterRanInterruptibly(result, error);
-      }
+      state = get();
+    }
+    if (restoreInterruptedBit) {
+      currentThread.interrupt();
     }
+    /*
+     * TODO(cpovirk): Clear interrupt status here? We currently don't, which means that an interrupt
+     * before, during, or after runInterruptibly() (unless it produced an InterruptedException
+     * caught above) can linger and affect listeners.
+     */
   }
 
   /**
@@ -145,13 +167,20 @@ public final void run() {
    * Do interruptible work here - do not complete Futures here, as their listeners could be
    * interrupted.
    */
+  @ParametricNullness
   abstract T runInterruptibly() throws Exception;
 
   /**
    * Any interruption that happens as a result of calling interruptTask will arrive before this
    * method is called. Complete Futures here.
    */
-  abstract void afterRanInterruptibly(@NullableDecl T result, @NullableDecl Throwable error);
+  abstract void afterRanInterruptiblySuccess(@ParametricNullness T result);
+
+  /**
+   * Any interruption that happens as a result of calling interruptTask will arrive before this
+   * method is called. Complete Futures here.
+   */
+  abstract void afterRanInterruptiblyFailure(Throwable error);
 
   /**
    * Interrupts the running task. Because this internally calls {@link Thread#interrupt()} which can
@@ -162,29 +191,59 @@ final void interruptTask() {
     // in this CAS, there's no risk of interrupting the wrong thread or interrupting a thread that
     // isn't currently executing this task.
     Runnable currentRunner = get();
-    if (currentRunner instanceof Thread && compareAndSet(currentRunner, INTERRUPTING)) {
-      // Thread.interrupt can throw aribitrary exceptions due to the nio InterruptibleChannel API
-      // This will make sure that tasks don't get stuck busy waiting.
-      // Some of this is fixed in jdk11 (see https://bugs.openjdk.java.net/browse/JDK-8198692) but
-      // not all.  See the test cases for examples on how this can happen.
-      try {
-        ((Thread) currentRunner).interrupt();
-      } finally {
-        Runnable prev = getAndSet(DONE);
-        if (prev == PARKED) {
-          LockSupport.unpark((Thread) currentRunner);
+    if (currentRunner instanceof Thread) {
+      Blocker blocker = new Blocker(this);
+      blocker.setOwner(Thread.currentThread());
+      if (compareAndSet(currentRunner, blocker)) {
+        // Thread.interrupt can throw arbitrary exceptions due to the nio InterruptibleChannel API
+        // This will make sure that tasks don't get stuck busy waiting.
+        // Some of this is fixed in jdk11 (see https://bugs.openjdk.java.net/browse/JDK-8198692) but
+        // not all.  See the test cases for examples on how this can happen.
+        try {
+          ((Thread) currentRunner).interrupt();
+        } finally {
+          Runnable prev = getAndSet(DONE);
+          if (prev == PARKED) {
+            LockSupport.unpark((Thread) currentRunner);
+          }
         }
       }
     }
   }
 
+  /**
+   * Using this as the blocker object allows introspection and debugging tools to see that the
+   * currentRunner thread is blocked on the progress of the interruptor thread, which can help
+   * identify deadlocks.
+   */
+  @VisibleForTesting
+  static final class Blocker extends AbstractOwnableSynchronizer implements Runnable {
+    private final InterruptibleTask<?> task;
+
+    private Blocker(InterruptibleTask<?> task) {
+      this.task = task;
+    }
+
+    @Override
+    public void run() {}
+
+    private void setOwner(Thread thread) {
+      super.setExclusiveOwnerThread(thread);
+    }
+
+    @Override
+    public String toString() {
+      return task.toString();
+    }
+  }
+
   @Override
   public final String toString() {
     Runnable state = get();
-    final String result;
+    String result;
     if (state == DONE) {
       result = "running=[DONE]";
-    } else if (state == INTERRUPTING) {
+    } else if (state instanceof Blocker) {
       result = "running=[INTERRUPTED]";
     } else if (state instanceof Thread) {
       // getName is final on Thread, no need to worry about exceptions
diff --git a/android/guava/src/com/google/common/util/concurrent/JdkFutureAdapters.java b/android/guava/src/com/google/common/util/concurrent/JdkFutureAdapters.java
index 1b84302e638d..0b0db4573ae2 100644
--- a/android/guava/src/com/google/common/util/concurrent/JdkFutureAdapters.java
+++ b/android/guava/src/com/google/common/util/concurrent/JdkFutureAdapters.java
@@ -24,6 +24,7 @@
 import java.util.concurrent.Future;
 import java.util.concurrent.ThreadFactory;
 import java.util.concurrent.atomic.AtomicBoolean;
+import org.checkerframework.checker.nullness.qual.Nullable;
 
 /**
  * Utilities necessary for working with libraries that supply plain {@link Future} instances. Note
@@ -35,6 +36,7 @@
  */
 @Beta
 @GwtIncompatible
+@ElementTypesAreNonnullByDefault
 public final class JdkFutureAdapters {
   /**
    * Assigns a thread to the given {@link Future} to provide {@link ListenableFuture} functionality.
@@ -49,11 +51,12 @@ public final class JdkFutureAdapters {
    * ListenableFutureTask}, {@link AbstractFuture}, and other utilities over creating plain {@code
    * Future} instances to be upgraded to {@code ListenableFuture} after the fact.
    */
-  public static <V> ListenableFuture<V> listenInPoolThread(Future<V> future) {
+  public static <V extends @Nullable Object> ListenableFuture<V> listenInPoolThread(
+      Future<V> future) {
     if (future instanceof ListenableFuture) {
       return (ListenableFuture<V>) future;
     }
-    return new ListenableFutureAdapter<V>(future);
+    return new ListenableFutureAdapter<>(future);
   }
 
   /**
@@ -76,12 +79,13 @@ public static <V> ListenableFuture<V> listenInPoolThread(Future<V> future) {
    *
    * @since 12.0
    */
-  public static <V> ListenableFuture<V> listenInPoolThread(Future<V> future, Executor executor) {
+  public static <V extends @Nullable Object> ListenableFuture<V> listenInPoolThread(
+      Future<V> future, Executor executor) {
     checkNotNull(executor);
     if (future instanceof ListenableFuture) {
       return (ListenableFuture<V>) future;
     }
-    return new ListenableFutureAdapter<V>(future, executor);
+    return new ListenableFutureAdapter<>(future, executor);
   }
 
   /**
@@ -93,8 +97,8 @@ public static <V> ListenableFuture<V> listenInPoolThread(Future<V> future, Execu
    * <p>If the delegate future is interrupted or throws an unexpected unchecked exception, the
    * listeners will not be invoked.
    */
-  private static class ListenableFutureAdapter<V> extends ForwardingFuture<V>
-      implements ListenableFuture<V> {
+  private static class ListenableFutureAdapter<V extends @Nullable Object>
+      extends ForwardingFuture<V> implements ListenableFuture<V> {
 
     private static final ThreadFactory threadFactory =
         new ThreadFactoryBuilder()
@@ -146,22 +150,19 @@ public void addListener(Runnable listener, Executor exec) {
 
         // TODO(lukes): handle RejectedExecutionException
         adapterExecutor.execute(
-            new Runnable() {
-              @Override
-              public void run() {
-                try {
-                  /*
-                   * Threads from our private pool are never interrupted. Threads from a
-                   * user-supplied executor might be, but... what can we do? This is another reason
-                   * to return a proper ListenableFuture instead of using listenInPoolThread.
-                   */
-                  getUninterruptibly(delegate);
-                } catch (Throwable e) {
-                  // ExecutionException / CancellationException / RuntimeException / Error
-                  // The task is presumably done, run the listeners.
-                }
-                executionList.execute();
+            () -> {
+              try {
+                /*
+                 * Threads from our private pool are never interrupted. Threads from a
+                 * user-supplied executor might be, but... what can we do? This is another reason
+                 * to return a proper ListenableFuture instead of using listenInPoolThread.
+                 */
+                getUninterruptibly(delegate);
+              } catch (Throwable e) {
+                // ExecutionException / CancellationException / RuntimeException / Error
+                // The task is presumably done, run the listeners.
               }
+              executionList.execute();
             });
       }
     }
diff --git a/android/guava/src/com/google/common/util/concurrent/ListenableFuture.java b/android/guava/src/com/google/common/util/concurrent/ListenableFuture.java
index 98e31ed37466..a8d9dd4de5f9 100644
--- a/android/guava/src/com/google/common/util/concurrent/ListenableFuture.java
+++ b/android/guava/src/com/google/common/util/concurrent/ListenableFuture.java
@@ -18,6 +18,7 @@
 import java.util.concurrent.Executor;
 import java.util.concurrent.Future;
 import java.util.concurrent.RejectedExecutionException;
+import org.checkerframework.checker.nullness.qual.Nullable;
 
 /**
  * A {@link Future} that accepts completion listeners. Each listener has an associated executor, and
@@ -99,8 +100,24 @@
  * @author Nishant Thakkar
  * @since 1.0
  */
+/*
+ * Some of the annotations below were added after we released our separate
+ * com.google.guava:listenablefuture:1.0 artifact. (For more on that artifact, see
+ * https://github.com/google/guava/releases/tag/v27.0) This means that the copy of ListenableFuture
+ * in com.google.guava:guava differs from the "frozen" copy in the listenablefuture artifact. This
+ * could in principle cause problems for some users. Still, we expect that the benefits of the
+ * nullness annotations in particular will outweigh the costs. (And it's worth noting that we have
+ * released multiple ListenableFuture.class files that are not byte-for-byte compatible even from
+ * the beginning, thanks to using different `-source -target` values for compiling our `-jre` and
+ * `-android` "flavors.")
+ *
+ * (We could consider releasing a listenablefuture:1.0.1 someday. But we would want to look into how
+ * that affects users, especially users of the Android Gradle Plugin, since the plugin developers
+ * put in a special hack for us: https://issuetracker.google.com/issues/131431257)
+ */
 @DoNotMock("Use the methods in Futures (like immediateFuture) or SettableFuture")
-public interface ListenableFuture<V> extends Future<V> {
+@ElementTypesAreNonnullByDefault
+public interface ListenableFuture<V extends @Nullable Object> extends Future<V> {
   /**
    * Registers a listener to be {@linkplain Executor#execute(Runnable) run} on the given executor.
    * The listener will run when the {@code Future}'s computation is {@linkplain Future#isDone()
diff --git a/android/guava/src/com/google/common/util/concurrent/ListenableFutureTask.java b/android/guava/src/com/google/common/util/concurrent/ListenableFutureTask.java
index 9f6f7e39875a..678a6c671a46 100644
--- a/android/guava/src/com/google/common/util/concurrent/ListenableFutureTask.java
+++ b/android/guava/src/com/google/common/util/concurrent/ListenableFutureTask.java
@@ -25,7 +25,7 @@
 import java.util.concurrent.FutureTask;
 import java.util.concurrent.TimeUnit;
 import java.util.concurrent.TimeoutException;
-import org.checkerframework.checker.nullness.compatqual.NullableDecl;
+import org.checkerframework.checker.nullness.qual.Nullable;
 
 /**
  * A {@link FutureTask} that also implements the {@link ListenableFuture} interface. Unlike {@code
@@ -41,7 +41,9 @@
  * @since 1.0
  */
 @GwtIncompatible
-public class ListenableFutureTask<V> extends FutureTask<V> implements ListenableFuture<V> {
+@ElementTypesAreNonnullByDefault
+public class ListenableFutureTask<V extends @Nullable Object> extends FutureTask<V>
+    implements ListenableFuture<V> {
   // TODO(cpovirk): explore ways of making ListenableFutureTask final. There are some valid reasons
   // such as BoundedQueueExecutorService to allow extends but it would be nice to make it final to
   // avoid unintended usage.
@@ -56,8 +58,8 @@ public class ListenableFutureTask<V> extends FutureTask<V> implements Listenable
    * @param callable the callable task
    * @since 10.0
    */
-  public static <V> ListenableFutureTask<V> create(Callable<V> callable) {
-    return new ListenableFutureTask<V>(callable);
+  public static <V extends @Nullable Object> ListenableFutureTask<V> create(Callable<V> callable) {
+    return new ListenableFutureTask<>(callable);
   }
 
   /**
@@ -70,15 +72,16 @@ public static <V> ListenableFutureTask<V> create(Callable<V> callable) {
    *     ListenableFutureTask.create(runnable, null)}
    * @since 10.0
    */
-  public static <V> ListenableFutureTask<V> create(Runnable runnable, @NullableDecl V result) {
-    return new ListenableFutureTask<V>(runnable, result);
+  public static <V extends @Nullable Object> ListenableFutureTask<V> create(
+      Runnable runnable, @ParametricNullness V result) {
+    return new ListenableFutureTask<>(runnable, result);
   }
 
   ListenableFutureTask(Callable<V> callable) {
     super(callable);
   }
 
-  ListenableFutureTask(Runnable runnable, @NullableDecl V result) {
+  ListenableFutureTask(Runnable runnable, @ParametricNullness V result) {
     super(runnable, result);
   }
 
@@ -89,6 +92,7 @@ public void addListener(Runnable listener, Executor exec) {
 
   @CanIgnoreReturnValue
   @Override
+  @ParametricNullness
   public V get(long timeout, TimeUnit unit)
       throws TimeoutException, InterruptedException, ExecutionException {
 
diff --git a/android/guava/src/com/google/common/util/concurrent/ListenableScheduledFuture.java b/android/guava/src/com/google/common/util/concurrent/ListenableScheduledFuture.java
index 77fa5f7fc69b..f6e5d9f9e1ec 100644
--- a/android/guava/src/com/google/common/util/concurrent/ListenableScheduledFuture.java
+++ b/android/guava/src/com/google/common/util/concurrent/ListenableScheduledFuture.java
@@ -14,9 +14,9 @@
 
 package com.google.common.util.concurrent;
 
-import com.google.common.annotations.Beta;
 import com.google.common.annotations.GwtCompatible;
 import java.util.concurrent.ScheduledFuture;
+import org.checkerframework.checker.nullness.qual.Nullable;
 
 /**
  * Helper interface to implement both {@link ListenableFuture} and {@link ScheduledFuture}.
@@ -24,6 +24,7 @@
  * @author Anthony Zana
  * @since 15.0
  */
-@Beta
 @GwtCompatible
-public interface ListenableScheduledFuture<V> extends ScheduledFuture<V>, ListenableFuture<V> {}
+@ElementTypesAreNonnullByDefault
+public interface ListenableScheduledFuture<V extends @Nullable Object>
+    extends ScheduledFuture<V>, ListenableFuture<V> {}
diff --git a/android/guava/src/com/google/common/util/concurrent/ListenerCallQueue.java b/android/guava/src/com/google/common/util/concurrent/ListenerCallQueue.java
index ee6b5b94c964..ed8c9065ac93 100644
--- a/android/guava/src/com/google/common/util/concurrent/ListenerCallQueue.java
+++ b/android/guava/src/com/google/common/util/concurrent/ListenerCallQueue.java
@@ -53,6 +53,7 @@
  * #dispatch} is expected to be called concurrently, it is idempotent.
  */
 @GwtIncompatible
+@ElementTypesAreNonnullByDefault
 final class ListenerCallQueue<L> {
   // TODO(cpovirk): consider using the logger associated with listener.getClass().
   private static final Logger logger = Logger.getLogger(ListenerCallQueue.class.getName());
@@ -123,7 +124,7 @@ public void dispatch() {
 
   /**
    * A special purpose queue/executor that dispatches listener events serially on a configured
-   * executor. Each event event can be added and dispatched as separate phases.
+   * executor. Each event can be added and dispatched as separate phases.
    *
    * <p>This class is very similar to {@link SequentialExecutor} with the exception that events can
    * be added without necessarily executing immediately.
diff --git a/android/guava/src/com/google/common/util/concurrent/ListeningExecutorService.java b/android/guava/src/com/google/common/util/concurrent/ListeningExecutorService.java
index 469eb6757a09..83ea759f8e74 100644
--- a/android/guava/src/com/google/common/util/concurrent/ListeningExecutorService.java
+++ b/android/guava/src/com/google/common/util/concurrent/ListeningExecutorService.java
@@ -23,6 +23,7 @@
 import java.util.concurrent.Future;
 import java.util.concurrent.RejectedExecutionException;
 import java.util.concurrent.TimeUnit;
+import org.checkerframework.checker.nullness.qual.Nullable;
 
 /**
  * An {@link ExecutorService} that returns {@link ListenableFuture} instances. To create an instance
@@ -36,13 +37,14 @@
     "Use TestingExecutors.sameThreadScheduledExecutor, or wrap a real Executor from "
         + "java.util.concurrent.Executors with MoreExecutors.listeningDecorator")
 @GwtIncompatible
+@ElementTypesAreNonnullByDefault
 public interface ListeningExecutorService extends ExecutorService {
   /**
    * @return a {@code ListenableFuture} representing pending completion of the task
    * @throws RejectedExecutionException {@inheritDoc}
    */
   @Override
-  <T> ListenableFuture<T> submit(Callable<T> task);
+  <T extends @Nullable Object> ListenableFuture<T> submit(Callable<T> task);
 
   /**
    * @return a {@code ListenableFuture} representing pending completion of the task
@@ -56,7 +58,8 @@ public interface ListeningExecutorService extends ExecutorService {
    * @throws RejectedExecutionException {@inheritDoc}
    */
   @Override
-  <T> ListenableFuture<T> submit(Runnable task, T result);
+  <T extends @Nullable Object> ListenableFuture<T> submit(
+      Runnable task, @ParametricNullness T result);
 
   /**
    * {@inheritDoc}
@@ -77,7 +80,7 @@ public interface ListeningExecutorService extends ExecutorService {
    * @throws NullPointerException if any task is null
    */
   @Override
-  <T> List<Future<T>> invokeAll(Collection<? extends Callable<T>> tasks)
+  <T extends @Nullable Object> List<Future<T>> invokeAll(Collection<? extends Callable<T>> tasks)
       throws InterruptedException;
 
   /**
@@ -100,7 +103,7 @@ <T> List<Future<T>> invokeAll(Collection<? extends Callable<T>> tasks)
    * @throws NullPointerException if any task is null
    */
   @Override
-  <T> List<Future<T>> invokeAll(
+  <T extends @Nullable Object> List<Future<T>> invokeAll(
       Collection<? extends Callable<T>> tasks, long timeout, TimeUnit unit)
       throws InterruptedException;
 }
diff --git a/android/guava/src/com/google/common/util/concurrent/ListeningScheduledExecutorService.java b/android/guava/src/com/google/common/util/concurrent/ListeningScheduledExecutorService.java
index 959a2fc28723..a6be949e574f 100644
--- a/android/guava/src/com/google/common/util/concurrent/ListeningScheduledExecutorService.java
+++ b/android/guava/src/com/google/common/util/concurrent/ListeningScheduledExecutorService.java
@@ -18,6 +18,7 @@
 import java.util.concurrent.Callable;
 import java.util.concurrent.ScheduledExecutorService;
 import java.util.concurrent.TimeUnit;
+import org.checkerframework.checker.nullness.qual.Nullable;
 
 /**
  * A {@link ScheduledExecutorService} that returns {@link ListenableFuture} instances from its
@@ -29,6 +30,7 @@
  * @since 10.0
  */
 @GwtIncompatible
+@ElementTypesAreNonnullByDefault
 public interface ListeningScheduledExecutorService
     extends ScheduledExecutorService, ListeningExecutorService {
 
@@ -38,7 +40,8 @@ public interface ListeningScheduledExecutorService
 
   /** @since 15.0 (previously returned ScheduledFuture) */
   @Override
-  <V> ListenableScheduledFuture<V> schedule(Callable<V> callable, long delay, TimeUnit unit);
+  <V extends @Nullable Object> ListenableScheduledFuture<V> schedule(
+      Callable<V> callable, long delay, TimeUnit unit);
 
   /** @since 15.0 (previously returned ScheduledFuture) */
   @Override
diff --git a/android/guava/src/com/google/common/util/concurrent/Monitor.java b/android/guava/src/com/google/common/util/concurrent/Monitor.java
index 27ee85d09ddf..d8da62de26ee 100644
--- a/android/guava/src/com/google/common/util/concurrent/Monitor.java
+++ b/android/guava/src/com/google/common/util/concurrent/Monitor.java
@@ -16,7 +16,6 @@
 
 import static com.google.common.base.Preconditions.checkNotNull;
 
-import com.google.common.annotations.Beta;
 import com.google.common.annotations.GwtIncompatible;
 import com.google.common.primitives.Longs;
 import com.google.errorprone.annotations.concurrent.GuardedBy;
@@ -24,7 +23,7 @@
 import java.util.concurrent.TimeUnit;
 import java.util.concurrent.locks.Condition;
 import java.util.concurrent.locks.ReentrantLock;
-import org.checkerframework.checker.nullness.compatqual.NullableDecl;
+import javax.annotation.CheckForNull;
 
 /**
  * A synchronization abstraction supporting waiting on arbitrary boolean conditions.
@@ -197,9 +196,9 @@
  * @author Martin Buchholz
  * @since 10.0
  */
-@Beta
 @GwtIncompatible
 @SuppressWarnings("GuardedBy") // TODO(b/35466881): Fix or suppress.
+@ElementTypesAreNonnullByDefault
 public final class Monitor {
   // TODO(user): Use raw LockSupport or AbstractQueuedSynchronizer instead of ReentrantLock.
   // TODO(user): "Port" jsr166 tests for ReentrantLock.
@@ -300,7 +299,6 @@ public final class Monitor {
    *
    * @since 10.0
    */
-  @Beta
   public abstract static class Guard {
 
     @Weak final Monitor monitor;
@@ -311,7 +309,7 @@ public abstract static class Guard {
 
     /** The next active guard */
     @GuardedBy("monitor.lock")
-    @NullableDecl
+    @CheckForNull
     Guard next;
 
     protected Guard(Monitor monitor) {
@@ -338,6 +336,7 @@ protected Guard(Monitor monitor) {
    * A linked list threaded through the Guard.next field.
    */
   @GuardedBy("lock")
+  @CheckForNull
   private Guard activeGuards = null;
 
   /**
@@ -733,7 +732,7 @@ public boolean tryEnterIf(Guard guard) {
    * @throws InterruptedException if interrupted while waiting
    */
   public void waitFor(Guard guard) throws InterruptedException {
-    if (!((guard.monitor == this) & lock.isHeldByCurrentThread())) {
+    if (!((guard.monitor == this) && lock.isHeldByCurrentThread())) {
       throw new IllegalMonitorStateException();
     }
     if (!guard.isSatisfied()) {
@@ -751,7 +750,7 @@ public void waitFor(Guard guard) throws InterruptedException {
   @SuppressWarnings("GoodTime") // should accept a java.time.Duration
   public boolean waitFor(Guard guard, long time, TimeUnit unit) throws InterruptedException {
     final long timeoutNanos = toSafeNanos(time, unit);
-    if (!((guard.monitor == this) & lock.isHeldByCurrentThread())) {
+    if (!((guard.monitor == this) && lock.isHeldByCurrentThread())) {
       throw new IllegalMonitorStateException();
     }
     if (guard.isSatisfied()) {
@@ -768,7 +767,7 @@ public boolean waitFor(Guard guard, long time, TimeUnit unit) throws Interrupted
    * currently occupying this monitor.
    */
   public void waitForUninterruptibly(Guard guard) {
-    if (!((guard.monitor == this) & lock.isHeldByCurrentThread())) {
+    if (!((guard.monitor == this) && lock.isHeldByCurrentThread())) {
       throw new IllegalMonitorStateException();
     }
     if (!guard.isSatisfied()) {
@@ -785,7 +784,7 @@ public void waitForUninterruptibly(Guard guard) {
   @SuppressWarnings("GoodTime") // should accept a java.time.Duration
   public boolean waitForUninterruptibly(Guard guard, long time, TimeUnit unit) {
     final long timeoutNanos = toSafeNanos(time, unit);
-    if (!((guard.monitor == this) & lock.isHeldByCurrentThread())) {
+    if (!((guard.monitor == this) && lock.isHeldByCurrentThread())) {
       throw new IllegalMonitorStateException();
     }
     if (guard.isSatisfied()) {
diff --git a/android/guava/src/com/google/common/util/concurrent/MoreExecutors.java b/android/guava/src/com/google/common/util/concurrent/MoreExecutors.java
index 708b896bf725..791a417c670f 100644
--- a/android/guava/src/com/google/common/util/concurrent/MoreExecutors.java
+++ b/android/guava/src/com/google/common/util/concurrent/MoreExecutors.java
@@ -49,6 +49,7 @@
 import java.util.concurrent.ThreadPoolExecutor;
 import java.util.concurrent.TimeUnit;
 import java.util.concurrent.TimeoutException;
+import org.checkerframework.checker.nullness.qual.Nullable;
 
 /**
  * Factory and utility methods for {@link java.util.concurrent.Executor}, {@link ExecutorService},
@@ -60,6 +61,7 @@
  * @since 3.0
  */
 @GwtCompatible(emulated = true)
+@ElementTypesAreNonnullByDefault
 public final class MoreExecutors {
   private MoreExecutors() {}
 
@@ -377,14 +379,22 @@ public static ListeningExecutorService newDirectExecutorService() {
    * difficult to reproduce because they depend on timing. For example:
    *
    * <ul>
-   *   <li>A call like {@code future.transform(function, directExecutor())} may execute the function
-   *       immediately in the thread that is calling {@code transform}. (This specific case happens
-   *       if the future is already completed.) If {@code transform} call was made from a UI thread
-   *       or other latency-sensitive thread, a heavyweight function can harm responsiveness.
-   *   <li>If the task will be executed later, consider which thread will trigger the execution --
-   *       since that thread will execute the task inline. If the thread is a shared system thread
-   *       like an RPC network thread, a heavyweight task can stall progress of the whole system or
-   *       even deadlock it.
+   *   <li>When a {@code ListenableFuture} listener is registered to run under {@code
+   *       directExecutor}, the listener can execute in any of three possible threads:
+   *       <ol>
+   *         <li>When a thread attaches a listener to a {@code ListenableFuture} that's already
+   *             complete, the listener runs immediately in that thread.
+   *         <li>When a thread attaches a listener to a {@code ListenableFuture} that's
+   *             <em>in</em>complete and the {@code ListenableFuture} later completes normally, the
+   *             listener runs in the the thread that completes the {@code ListenableFuture}.
+   *         <li>When a listener is attached to a {@code ListenableFuture} and the {@code
+   *             ListenableFuture} gets cancelled, the listener runs immediately in the the thread
+   *             that cancelled the {@code Future}.
+   *       </ol>
+   *       Given all these possibilities, it is frequently possible for listeners to execute in UI
+   *       threads, RPC network threads, or other latency-sensitive threads. In those cases, slow
+   *       listeners can harm responsiveness, slow the system as a whole, or worse. (See also the
+   *       note about locking below.)
    *   <li>If many tasks will be triggered by the same event, one heavyweight task may delay other
    *       tasks -- even tasks that are not themselves {@code directExecutor} tasks.
    *   <li>If many such tasks are chained together (such as with {@code
@@ -392,11 +402,19 @@ public static ListeningExecutorService newDirectExecutorService() {
    *       (In simple cases, callers can avoid this by registering all tasks with the same {@link
    *       MoreExecutors#newSequentialExecutor} wrapper around {@code directExecutor()}. More
    *       complex cases may require using thread pools or making deeper changes.)
+   *   <li>If an exception propagates out of a {@code Runnable}, it is not necessarily seen by any
+   *       {@code UncaughtExceptionHandler} for the thread. For example, if the callback passed to
+   *       {@link Futures#addCallback} throws an exception, that exception will be typically be
+   *       logged by the {@link ListenableFuture} implementation, even if the thread is configured
+   *       to do something different. In other cases, no code will catch the exception, and it may
+   *       terminate whichever thread happens to trigger the execution.
    * </ul>
    *
-   * Additionally, beware of executing tasks with {@code directExecutor} while holding a lock. Since
-   * the task you submit to the executor (or any other arbitrary work the executor does) may do slow
-   * work or acquire other locks, you risk deadlocks.
+   * A specific warning about locking: Code that executes user-supplied tasks, such as {@code
+   * ListenableFuture} listeners, should take care not to do so while holding a lock. Additionally,
+   * as a further line of defense, prefer not to perform any locking inside a task that will be run
+   * under {@code directExecutor}: Not only might the wait for a lock be long, but if the running
+   * thread was holding a lock, the listener may deadlock or break lock isolation.
    *
    * <p>This instance is equivalent to:
    *
@@ -419,8 +437,11 @@ public static Executor directExecutor() {
 
   /**
    * Returns an {@link Executor} that runs each task executed sequentially, such that no two tasks
-   * are running concurrently. Submitted tasks have a happens-before order as defined in the Java
-   * Language Specification.
+   * are running concurrently.
+   *
+   * <p>{@linkplain Executor#execute executed} tasks have a happens-before order as defined in the
+   * Java Language Specification. Tasks execute with the same happens-before order that the function
+   * calls to {@link Executor#execute `execute()`} that submitted those tasks had.
    *
    * <p>The executor uses {@code delegate} in order to {@link Executor#execute execute} each task in
    * turn, and does not create any threads of its own.
@@ -458,7 +479,6 @@ public static Executor directExecutor() {
    *
    * @since 23.3 (since 23.1 as {@code sequentialExecutor})
    */
-  @Beta
   @GwtIncompatible
   public static Executor newSequentialExecutor(Executor delegate) {
     return new SequentialExecutor(delegate);
@@ -549,6 +569,11 @@ public final List<Runnable> shutdownNow() {
     public final void execute(Runnable command) {
       delegate.execute(command);
     }
+
+    @Override
+    public final String toString() {
+      return super.toString() + "[" + delegate + "]";
+    }
   }
 
   @GwtIncompatible // TODO
@@ -564,13 +589,14 @@ private static final class ScheduledListeningDecorator extends ListeningDecorato
 
     @Override
     public ListenableScheduledFuture<?> schedule(Runnable command, long delay, TimeUnit unit) {
-      TrustedListenableFutureTask<Void> task = TrustedListenableFutureTask.create(command, null);
+      TrustedListenableFutureTask<@Nullable Void> task =
+          TrustedListenableFutureTask.create(command, null);
       ScheduledFuture<?> scheduled = delegate.schedule(task, delay, unit);
-      return new ListenableScheduledTask<>(task, scheduled);
+      return new ListenableScheduledTask<@Nullable Void>(task, scheduled);
     }
 
     @Override
-    public <V> ListenableScheduledFuture<V> schedule(
+    public <V extends @Nullable Object> ListenableScheduledFuture<V> schedule(
         Callable<V> callable, long delay, TimeUnit unit) {
       TrustedListenableFutureTask<V> task = TrustedListenableFutureTask.create(callable);
       ScheduledFuture<?> scheduled = delegate.schedule(task, delay, unit);
@@ -582,7 +608,7 @@ public ListenableScheduledFuture<?> scheduleAtFixedRate(
         Runnable command, long initialDelay, long period, TimeUnit unit) {
       NeverSuccessfulListenableFutureTask task = new NeverSuccessfulListenableFutureTask(command);
       ScheduledFuture<?> scheduled = delegate.scheduleAtFixedRate(task, initialDelay, period, unit);
-      return new ListenableScheduledTask<>(task, scheduled);
+      return new ListenableScheduledTask<@Nullable Void>(task, scheduled);
     }
 
     @Override
@@ -591,10 +617,10 @@ public ListenableScheduledFuture<?> scheduleWithFixedDelay(
       NeverSuccessfulListenableFutureTask task = new NeverSuccessfulListenableFutureTask(command);
       ScheduledFuture<?> scheduled =
           delegate.scheduleWithFixedDelay(task, initialDelay, delay, unit);
-      return new ListenableScheduledTask<>(task, scheduled);
+      return new ListenableScheduledTask<@Nullable Void>(task, scheduled);
     }
 
-    private static final class ListenableScheduledTask<V>
+    private static final class ListenableScheduledTask<V extends @Nullable Object>
         extends SimpleForwardingListenableFuture<V> implements ListenableScheduledFuture<V> {
 
       private final ScheduledFuture<?> scheduledDelegate;
@@ -630,7 +656,7 @@ public int compareTo(Delayed other) {
 
     @GwtIncompatible // TODO
     private static final class NeverSuccessfulListenableFutureTask
-        extends AbstractFuture.TrustedFuture<Void> implements Runnable {
+        extends AbstractFuture.TrustedFuture<@Nullable Void> implements Runnable {
       private final Runnable delegate;
 
       public NeverSuccessfulListenableFutureTask(Runnable delegate) {
@@ -646,6 +672,11 @@ public void run() {
           throw Throwables.propagate(t);
         }
       }
+
+      @Override
+      protected String pendingToString() {
+        return "task=[" + delegate + "]";
+      }
     }
   }
 
@@ -666,7 +697,8 @@ public void run() {
    */
   @SuppressWarnings("GoodTime") // should accept a java.time.Duration
   @GwtIncompatible
-  static <T> T invokeAnyImpl(
+  @ParametricNullness
+  static <T extends @Nullable Object> T invokeAnyImpl(
       ListeningExecutorService executorService,
       Collection<? extends Callable<T>> tasks,
       boolean timed,
@@ -746,7 +778,7 @@ static <T> T invokeAnyImpl(
    * Submits the task and adds a listener that adds the future to {@code queue} when it completes.
    */
   @GwtIncompatible // TODO
-  private static <T> ListenableFuture<T> submitAndAddQueueListener(
+  private static <T extends @Nullable Object> ListenableFuture<T> submitAndAddQueueListener(
       ListeningExecutorService executorService,
       Callable<T> task,
       final BlockingQueue<Future<T>> queue) {
@@ -891,7 +923,7 @@ static ExecutorService renamingDecorator(
     checkNotNull(nameSupplier);
     return new WrappingExecutorService(service) {
       @Override
-      protected <T> Callable<T> wrapTask(Callable<T> callable) {
+      protected <T extends @Nullable Object> Callable<T> wrapTask(Callable<T> callable) {
         return Callables.threadRenaming(callable, nameSupplier);
       }
 
@@ -920,7 +952,7 @@ static ScheduledExecutorService renamingDecorator(
     checkNotNull(nameSupplier);
     return new WrappingScheduledExecutorService(service) {
       @Override
-      protected <T> Callable<T> wrapTask(Callable<T> callable) {
+      protected <T extends @Nullable Object> Callable<T> wrapTask(Callable<T> callable) {
         return Callables.threadRenaming(callable, nameSupplier);
       }
 
diff --git a/android/guava/src/com/google/common/util/concurrent/NullnessCasts.java b/android/guava/src/com/google/common/util/concurrent/NullnessCasts.java
new file mode 100644
index 000000000000..a3a914e8970a
--- /dev/null
+++ b/android/guava/src/com/google/common/util/concurrent/NullnessCasts.java
@@ -0,0 +1,76 @@
+/*
+ * Copyright (C) 2021 The Guava Authors
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file except
+ * in compliance with the License. You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software distributed under the License
+ * is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express
+ * or implied. See the License for the specific language governing permissions and limitations under
+ * the License.
+ */
+
+package com.google.common.util.concurrent;
+
+import com.google.common.annotations.GwtCompatible;
+import javax.annotation.CheckForNull;
+import org.checkerframework.checker.nullness.qual.Nullable;
+
+/** A utility method to perform unchecked casts to suppress errors produced by nullness analyses. */
+@GwtCompatible
+@ElementTypesAreNonnullByDefault
+final class NullnessCasts {
+  /**
+   * Accepts a {@code @Nullable T} and returns a plain {@code T}, without performing any check that
+   * that conversion is safe.
+   *
+   * <p>This method is intended to help with usages of type parameters that have {@linkplain
+   * ParametricNullness parametric nullness}. If a type parameter instead ranges over only non-null
+   * types (or if the type is a non-variable type, like {@code String}), then code should almost
+   * never use this method, preferring instead to call {@code requireNonNull} so as to benefit from
+   * its runtime check.
+   *
+   * <p>An example use case for this method is in implementing an {@code Iterator<T>} whose {@code
+   * next} field is lazily initialized. The type of that field would be {@code @Nullable T}, and the
+   * code would be responsible for populating a "real" {@code T} (which might still be the value
+   * {@code null}!) before returning it to callers. Depending on how the code is structured, a
+   * nullness analysis might not understand that the field has been populated. To avoid that problem
+   * without having to add {@code @SuppressWarnings}, the code can call this method.
+   *
+   * <p>Why <i>not</i> just add {@code SuppressWarnings}? The problem is that this method is
+   * typically useful for {@code return} statements. That leaves the code with two options: Either
+   * add the suppression to the whole method (which turns off checking for a large section of code),
+   * or extract a variable, and put the suppression on that. However, a local variable typically
+   * doesn't work: Because nullness analyses typically infer the nullness of local variables,
+   * there's no way to assign a {@code @Nullable T} to a field {@code T foo;} and instruct the
+   * analysis that that means "plain {@code T}" rather than the inferred type {@code @Nullable T}.
+   * (Even if supported added {@code @NonNull}, that would not help, since the problem case
+   * addressed by this method is the case in which {@code T} has parametric nullness -- and thus its
+   * value may be legitimately {@code null}.)
+   */
+  @SuppressWarnings("nullness")
+  @ParametricNullness
+  static <T extends @Nullable Object> T uncheckedCastNullableTToT(@CheckForNull T t) {
+    return t;
+  }
+
+  /**
+   * Returns {@code null} cast to any type.
+   *
+   * <p>This method is intended to help with usages of type parameters that have {@linkplain
+   * ParametricNullness parametric nullness}. Sometimes, code may receive a null {@code T} but store
+   * a "null sentinel" to take its place. When the time comes to convert it back to a {@code T} to
+   * return to a caller, the code needs to a way to return {@code null} from a method that returns
+   * "plain {@code T}." This API provides that.
+   */
+  @SuppressWarnings({"nullness", "TypeParameterUnusedInFormals", "ReturnMissingNullable"})
+  // The warnings are legitimate. Each time we use this method, we document why.
+  @ParametricNullness
+  static <T extends @Nullable Object> T uncheckedNull() {
+    return null;
+  }
+
+  private NullnessCasts() {}
+}
diff --git a/android/guava/src/com/google/common/util/concurrent/OverflowAvoidingLockSupport.java b/android/guava/src/com/google/common/util/concurrent/OverflowAvoidingLockSupport.java
index ae871e03eb29..3038ab7bd004 100644
--- a/android/guava/src/com/google/common/util/concurrent/OverflowAvoidingLockSupport.java
+++ b/android/guava/src/com/google/common/util/concurrent/OverflowAvoidingLockSupport.java
@@ -17,19 +17,20 @@
 import static java.lang.Math.min;
 
 import java.util.concurrent.locks.LockSupport;
-import org.checkerframework.checker.nullness.compatqual.NullableDecl;
+import javax.annotation.CheckForNull;
 
 /**
  * Works around an android bug, where parking for more than INT_MAX seconds can produce an abort
  * signal on 32 bit devices running Android Q.
  */
+@ElementTypesAreNonnullByDefault
 final class OverflowAvoidingLockSupport {
   // Represents the max nanoseconds representable on a linux timespec with a 32 bit tv_sec
   static final long MAX_NANOSECONDS_THRESHOLD = (1L + Integer.MAX_VALUE) * 1_000_000_000L - 1L;
 
   private OverflowAvoidingLockSupport() {}
 
-  static void parkNanos(@NullableDecl Object blocker, long nanos) {
+  static void parkNanos(@CheckForNull Object blocker, long nanos) {
     // Even in the extremely unlikely event that a thread unblocks itself early after only 68 years,
     // this is indistinguishable from a spurious wakeup, which LockSupport allows.
     LockSupport.parkNanos(blocker, min(nanos, MAX_NANOSECONDS_THRESHOLD));
diff --git a/android/guava/src/com/google/common/util/concurrent/ParametricNullness.java b/android/guava/src/com/google/common/util/concurrent/ParametricNullness.java
new file mode 100644
index 000000000000..a745bf7bb4b8
--- /dev/null
+++ b/android/guava/src/com/google/common/util/concurrent/ParametricNullness.java
@@ -0,0 +1,52 @@
+/*
+ * Copyright (C) 2021 The Guava Authors
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package com.google.common.util.concurrent;
+
+import static java.lang.annotation.ElementType.FIELD;
+import static java.lang.annotation.ElementType.METHOD;
+import static java.lang.annotation.ElementType.PARAMETER;
+import static java.lang.annotation.RetentionPolicy.RUNTIME;
+
+import com.google.common.annotations.GwtCompatible;
+import java.lang.annotation.Retention;
+import java.lang.annotation.Target;
+
+/**
+ * Marks a "top-level" type-variable usage as the closest we can get to "non-nullable when
+ * non-nullable; nullable when nullable" (like the Android <a
+ * href="https://android.googlesource.com/platform/libcore/+/master/luni/src/main/java/libcore/util/NullFromTypeParam.java">{@code
+ * NullFromTypeParam}</a>).
+ *
+ * <p>Consumers of this annotation include:
+ *
+ * <ul>
+ *   <li>Kotlin, for which it makes the type-variable usage (a) a Kotlin platform type when the type
+ *       argument is non-nullable and (b) nullable when the type argument is nullable. We use this
+ *       to "undo" {@link ElementTypesAreNonnullByDefault}.
+ *   <li><a href="https://developers.google.com/j2objc">J2ObjC</a>
+ *   <li>{@code NullPointerTester}, at least in the Android backport (where the type-use annotations
+ *       {@code NullPointerTester} would need are not available) and in case of <a
+ *       href="https://bugs.openjdk.java.net/browse/JDK-8202469">JDK-8202469</a>
+ * </ul>
+ *
+ */
+@GwtCompatible
+@Retention(RUNTIME)
+@Target({FIELD, METHOD, PARAMETER})
+@javax.annotation.meta.TypeQualifierNickname
+@javax.annotation.Nonnull(when = javax.annotation.meta.When.UNKNOWN)
+@interface ParametricNullness {}
diff --git a/android/guava/src/com/google/common/util/concurrent/Partially.java b/android/guava/src/com/google/common/util/concurrent/Partially.java
index c40ab4e007ee..7aa16e776fd5 100644
--- a/android/guava/src/com/google/common/util/concurrent/Partially.java
+++ b/android/guava/src/com/google/common/util/concurrent/Partially.java
@@ -32,6 +32,7 @@
  * version.
  */
 @GwtCompatible
+@ElementTypesAreNonnullByDefault
 final class Partially {
   /**
    * The presence of this annotation on an API indicates that the method <i>may</i> be used with the
diff --git a/android/guava/src/com/google/common/util/concurrent/Platform.java b/android/guava/src/com/google/common/util/concurrent/Platform.java
index 94e6700fd031..cfb96a0ad788 100644
--- a/android/guava/src/com/google/common/util/concurrent/Platform.java
+++ b/android/guava/src/com/google/common/util/concurrent/Platform.java
@@ -15,13 +15,14 @@
 package com.google.common.util.concurrent;
 
 import com.google.common.annotations.GwtCompatible;
-import org.checkerframework.checker.nullness.compatqual.NullableDecl;
+import javax.annotation.CheckForNull;
 
 /** Methods factored out so that they can be emulated differently in GWT. */
 @GwtCompatible(emulated = true)
+@ElementTypesAreNonnullByDefault
 final class Platform {
   static boolean isInstanceOfThrowableClass(
-      @NullableDecl Throwable t, Class<? extends Throwable> expectedClass) {
+      @CheckForNull Throwable t, Class<? extends Throwable> expectedClass) {
     return expectedClass.isInstance(t);
   }
 
diff --git a/android/guava/src/com/google/common/util/concurrent/RateLimiter.java b/android/guava/src/com/google/common/util/concurrent/RateLimiter.java
index 99824ee47bec..9bcf118160d5 100644
--- a/android/guava/src/com/google/common/util/concurrent/RateLimiter.java
+++ b/android/guava/src/com/google/common/util/concurrent/RateLimiter.java
@@ -29,7 +29,7 @@
 import com.google.errorprone.annotations.CanIgnoreReturnValue;
 import java.util.Locale;
 import java.util.concurrent.TimeUnit;
-import org.checkerframework.checker.nullness.compatqual.NullableDecl;
+import javax.annotation.CheckForNull;
 
 /**
  * A rate limiter. Conceptually, a rate limiter distributes permits at a configurable rate. Each
@@ -92,6 +92,7 @@
 // would mean a maximum rate of "1MB/s", which might be small in some cases.
 @Beta
 @GwtIncompatible
+@ElementTypesAreNonnullByDefault
 public abstract class RateLimiter {
   /**
    * Creates a {@code RateLimiter} with the specified stable throughput, given as "permits per
@@ -184,7 +185,7 @@ static RateLimiter create(
   private final SleepingStopwatch stopwatch;
 
   // Can't be initialized in the constructor because mocks don't call the constructor.
-  @NullableDecl private volatile Object mutexDoNotUseDirectly;
+  @CheckForNull private volatile Object mutexDoNotUseDirectly;
 
   private Object mutex() {
     Object mutex = mutexDoNotUseDirectly;
diff --git a/android/guava/src/com/google/common/util/concurrent/Runnables.java b/android/guava/src/com/google/common/util/concurrent/Runnables.java
index e1ebd2389515..5503f68ae545 100644
--- a/android/guava/src/com/google/common/util/concurrent/Runnables.java
+++ b/android/guava/src/com/google/common/util/concurrent/Runnables.java
@@ -24,6 +24,7 @@
  */
 @Beta
 @GwtCompatible
+@ElementTypesAreNonnullByDefault
 public final class Runnables {
 
   private static final Runnable EMPTY_RUNNABLE =
diff --git a/android/guava/src/com/google/common/util/concurrent/SequentialExecutor.java b/android/guava/src/com/google/common/util/concurrent/SequentialExecutor.java
index 4fd50b94ee79..d0b600be840e 100644
--- a/android/guava/src/com/google/common/util/concurrent/SequentialExecutor.java
+++ b/android/guava/src/com/google/common/util/concurrent/SequentialExecutor.java
@@ -31,6 +31,7 @@
 import java.util.concurrent.RejectedExecutionException;
 import java.util.logging.Level;
 import java.util.logging.Logger;
+import javax.annotation.CheckForNull;
 
 /**
  * Executor ensuring that all Runnables submitted are executed in order, using the provided
@@ -47,6 +48,7 @@
  * restarted by a call to {@link #execute}.
  */
 @GwtIncompatible
+@ElementTypesAreNonnullByDefault
 final class SequentialExecutor implements Executor {
   private static final Logger log = Logger.getLogger(SequentialExecutor.class.getName());
 
@@ -94,10 +96,10 @@ enum WorkerRunningState {
    * execution of tasks will stop until a call to this method is made.
    */
   @Override
-  public void execute(final Runnable task) {
+  public void execute(Runnable task) {
     checkNotNull(task);
-    final Runnable submittedTask;
-    final long oldRunCount;
+    Runnable submittedTask;
+    long oldRunCount;
     synchronized (queue) {
       // If the worker is already running (or execute() on the delegate returned successfully, and
       // the worker has yet to start) then we don't need to start the worker.
@@ -170,7 +172,7 @@ public String toString() {
 
   /** Worker that runs tasks from {@link #queue} until it is empty. */
   private final class QueueWorker implements Runnable {
-    Runnable task;
+    @CheckForNull Runnable task;
 
     @Override
     public void run() {
diff --git a/android/guava/src/com/google/common/util/concurrent/Service.java b/android/guava/src/com/google/common/util/concurrent/Service.java
index 2c6cdabd3ce0..0999a30ae5f4 100644
--- a/android/guava/src/com/google/common/util/concurrent/Service.java
+++ b/android/guava/src/com/google/common/util/concurrent/Service.java
@@ -53,6 +53,7 @@
  */
 @DoNotMock("Create an AbstractIdleService")
 @GwtIncompatible
+@ElementTypesAreNonnullByDefault
 public interface Service {
   /**
    * If the service state is {@link State#NEW}, this initiates service startup and returns
@@ -175,61 +176,28 @@ public interface Service {
    */
   enum State {
     /** A service in this state is inactive. It does minimal work and consumes minimal resources. */
-    NEW {
-      @Override
-      boolean isTerminal() {
-        return false;
-      }
-    },
+    NEW,
 
     /** A service in this state is transitioning to {@link #RUNNING}. */
-    STARTING {
-      @Override
-      boolean isTerminal() {
-        return false;
-      }
-    },
+    STARTING,
 
     /** A service in this state is operational. */
-    RUNNING {
-      @Override
-      boolean isTerminal() {
-        return false;
-      }
-    },
+    RUNNING,
 
     /** A service in this state is transitioning to {@link #TERMINATED}. */
-    STOPPING {
-      @Override
-      boolean isTerminal() {
-        return false;
-      }
-    },
+    STOPPING,
 
     /**
      * A service in this state has completed execution normally. It does minimal work and consumes
      * minimal resources.
      */
-    TERMINATED {
-      @Override
-      boolean isTerminal() {
-        return true;
-      }
-    },
+    TERMINATED,
 
     /**
      * A service in this state has encountered a problem and may not be operational. It cannot be
      * started nor stopped.
      */
-    FAILED {
-      @Override
-      boolean isTerminal() {
-        return true;
-      }
-    };
-
-    /** Returns true if this state is terminal. */
-    abstract boolean isTerminal();
+    FAILED,
   }
 
   /**
diff --git a/android/guava/src/com/google/common/util/concurrent/ServiceManager.java b/android/guava/src/com/google/common/util/concurrent/ServiceManager.java
index e5c5e141bf77..5177b5ac05dd 100644
--- a/android/guava/src/com/google/common/util/concurrent/ServiceManager.java
+++ b/android/guava/src/com/google/common/util/concurrent/ServiceManager.java
@@ -118,6 +118,7 @@
  * @since 14.0
  */
 @GwtIncompatible
+@ElementTypesAreNonnullByDefault
 public final class ServiceManager implements ServiceManagerBridge {
   private static final Logger logger = Logger.getLogger(ServiceManager.class.getName());
   private static final ListenerCallQueue.Event<Listener> HEALTHY_EVENT =
@@ -261,8 +262,7 @@ public void addListener(Listener listener, Executor executor) {
   @CanIgnoreReturnValue
   public ServiceManager startAsync() {
     for (Service service : services) {
-      State state = service.state();
-      checkState(state == NEW, "Service %s is %s, cannot start it.", service, state);
+      checkState(service.state() == NEW, "Not all services are NEW, cannot start %s", this);
     }
     for (Service service : services) {
       try {
@@ -595,9 +595,9 @@ ImmutableMap<Service, Long> startupTimes() {
         // N.B. There will only be an entry in the map if the service has started
         for (Entry<Service, Stopwatch> entry : startupTimers.entrySet()) {
           Service service = entry.getKey();
-          Stopwatch stopWatch = entry.getValue();
-          if (!stopWatch.isRunning() && !(service instanceof NoOpService)) {
-            loadTimes.add(Maps.immutableEntry(service, stopWatch.elapsed(MILLISECONDS)));
+          Stopwatch stopwatch = entry.getValue();
+          if (!stopwatch.isRunning() && !(service instanceof NoOpService)) {
+            loadTimes.add(Maps.immutableEntry(service, stopwatch.elapsed(MILLISECONDS)));
           }
         }
       } finally {
diff --git a/android/guava/src/com/google/common/util/concurrent/ServiceManagerBridge.java b/android/guava/src/com/google/common/util/concurrent/ServiceManagerBridge.java
index a9300a616679..7ae430e3d251 100644
--- a/android/guava/src/com/google/common/util/concurrent/ServiceManagerBridge.java
+++ b/android/guava/src/com/google/common/util/concurrent/ServiceManagerBridge.java
@@ -26,6 +26,7 @@
  * {@code servicesByState()} to return {@code ImmutableMultimap}.
  */
 @GwtIncompatible
+@ElementTypesAreNonnullByDefault
 interface ServiceManagerBridge {
   ImmutableMultimap<State, Service> servicesByState();
 }
diff --git a/android/guava/src/com/google/common/util/concurrent/SettableFuture.java b/android/guava/src/com/google/common/util/concurrent/SettableFuture.java
index 1c220e607cf0..0a9e194657f8 100644
--- a/android/guava/src/com/google/common/util/concurrent/SettableFuture.java
+++ b/android/guava/src/com/google/common/util/concurrent/SettableFuture.java
@@ -16,7 +16,7 @@
 
 import com.google.common.annotations.GwtCompatible;
 import com.google.errorprone.annotations.CanIgnoreReturnValue;
-import org.checkerframework.checker.nullness.compatqual.NullableDecl;
+import org.checkerframework.checker.nullness.qual.Nullable;
 
 /**
  * A {@link ListenableFuture} whose result can be set by a {@link #set(Object)}, {@link
@@ -33,17 +33,19 @@
  * @since 9.0 (in 1.0 as {@code ValueFuture})
  */
 @GwtCompatible
-public final class SettableFuture<V> extends AbstractFuture.TrustedFuture<V> {
+@ElementTypesAreNonnullByDefault
+public final class SettableFuture<V extends @Nullable Object>
+    extends AbstractFuture.TrustedFuture<V> {
   /**
    * Creates a new {@code SettableFuture} that can be completed or cancelled by a later method call.
    */
-  public static <V> SettableFuture<V> create() {
-    return new SettableFuture<V>();
+  public static <V extends @Nullable Object> SettableFuture<V> create() {
+    return new SettableFuture<>();
   }
 
   @CanIgnoreReturnValue
   @Override
-  public boolean set(@NullableDecl V value) {
+  public boolean set(@ParametricNullness V value) {
     return super.set(value);
   }
 
diff --git a/android/guava/src/com/google/common/util/concurrent/SimpleTimeLimiter.java b/android/guava/src/com/google/common/util/concurrent/SimpleTimeLimiter.java
index 9d0b81bce26a..c6ade6a3a0a5 100644
--- a/android/guava/src/com/google/common/util/concurrent/SimpleTimeLimiter.java
+++ b/android/guava/src/com/google/common/util/concurrent/SimpleTimeLimiter.java
@@ -34,6 +34,8 @@
 import java.util.concurrent.Future;
 import java.util.concurrent.TimeUnit;
 import java.util.concurrent.TimeoutException;
+import javax.annotation.CheckForNull;
+import org.checkerframework.checker.nullness.qual.Nullable;
 
 /**
  * A TimeLimiter that runs method calls in the background using an {@link ExecutorService}. If the
@@ -45,6 +47,7 @@
  */
 @Beta
 @GwtIncompatible
+@ElementTypesAreNonnullByDefault
 public final class SimpleTimeLimiter implements TimeLimiter {
 
   private final ExecutorService executor;
@@ -70,32 +73,27 @@ public static SimpleTimeLimiter create(ExecutorService executor) {
 
   @Override
   public <T> T newProxy(
-      final T target,
-      Class<T> interfaceType,
-      final long timeoutDuration,
-      final TimeUnit timeoutUnit) {
+      T target, Class<T> interfaceType, long timeoutDuration, TimeUnit timeoutUnit) {
     checkNotNull(target);
     checkNotNull(interfaceType);
     checkNotNull(timeoutUnit);
     checkPositiveTimeout(timeoutDuration);
     checkArgument(interfaceType.isInterface(), "interfaceType must be an interface type");
 
-    final Set<Method> interruptibleMethods = findInterruptibleMethods(interfaceType);
+    Set<Method> interruptibleMethods = findInterruptibleMethods(interfaceType);
 
     InvocationHandler handler =
         new InvocationHandler() {
           @Override
-          public Object invoke(Object obj, final Method method, final Object[] args)
+          @CheckForNull
+          public Object invoke(Object obj, Method method, @CheckForNull @Nullable Object[] args)
               throws Throwable {
-            Callable<Object> callable =
-                new Callable<Object>() {
-                  @Override
-                  public Object call() throws Exception {
-                    try {
-                      return method.invoke(target, args);
-                    } catch (InvocationTargetException e) {
-                      throw throwCause(e, false /* combineStackTraces */);
-                    }
+            Callable<@Nullable Object> callable =
+                () -> {
+                  try {
+                    return method.invoke(target, args);
+                  } catch (InvocationTargetException e) {
+                    throw throwCause(e, false /* combineStackTraces */);
                   }
                 };
             return callWithTimeout(
@@ -113,7 +111,7 @@ private static <T> T newProxy(Class<T> interfaceType, InvocationHandler handler)
     return interfaceType.cast(object);
   }
 
-  private <T> T callWithTimeout(
+  private <T extends @Nullable Object> T callWithTimeout(
       Callable<T> callable, long timeoutDuration, TimeUnit timeoutUnit, boolean amInterruptible)
       throws Exception {
     checkNotNull(callable);
@@ -143,7 +141,8 @@ private <T> T callWithTimeout(
 
   @CanIgnoreReturnValue
   @Override
-  public <T> T callWithTimeout(Callable<T> callable, long timeoutDuration, TimeUnit timeoutUnit)
+  public <T extends @Nullable Object> T callWithTimeout(
+      Callable<T> callable, long timeoutDuration, TimeUnit timeoutUnit)
       throws TimeoutException, InterruptedException, ExecutionException {
     checkNotNull(callable);
     checkNotNull(timeoutUnit);
@@ -164,7 +163,7 @@ public <T> T callWithTimeout(Callable<T> callable, long timeoutDuration, TimeUni
 
   @CanIgnoreReturnValue
   @Override
-  public <T> T callUninterruptiblyWithTimeout(
+  public <T extends @Nullable Object> T callUninterruptiblyWithTimeout(
       Callable<T> callable, long timeoutDuration, TimeUnit timeoutUnit)
       throws TimeoutException, ExecutionException {
     checkNotNull(callable);
diff --git a/android/guava/src/com/google/common/util/concurrent/SmoothRateLimiter.java b/android/guava/src/com/google/common/util/concurrent/SmoothRateLimiter.java
index d4b4aa11ee0c..ca78905908ed 100644
--- a/android/guava/src/com/google/common/util/concurrent/SmoothRateLimiter.java
+++ b/android/guava/src/com/google/common/util/concurrent/SmoothRateLimiter.java
@@ -22,6 +22,7 @@
 import java.util.concurrent.TimeUnit;
 
 @GwtIncompatible
+@ElementTypesAreNonnullByDefault
 abstract class SmoothRateLimiter extends RateLimiter {
   /*
    * How is the RateLimiter designed, and why?
diff --git a/android/guava/src/com/google/common/util/concurrent/Striped.java b/android/guava/src/com/google/common/util/concurrent/Striped.java
index c9ba77235d5a..2ea61cb3248a 100644
--- a/android/guava/src/com/google/common/util/concurrent/Striped.java
+++ b/android/guava/src/com/google/common/util/concurrent/Striped.java
@@ -14,6 +14,8 @@
 
 package com.google.common.util.concurrent;
 
+import static com.google.common.collect.Lists.newArrayList;
+
 import com.google.common.annotations.Beta;
 import com.google.common.annotations.GwtIncompatible;
 import com.google.common.annotations.VisibleForTesting;
@@ -21,7 +23,6 @@
 import com.google.common.base.Preconditions;
 import com.google.common.base.Supplier;
 import com.google.common.collect.ImmutableList;
-import com.google.common.collect.Iterables;
 import com.google.common.collect.MapMaker;
 import com.google.common.math.IntMath;
 import com.google.common.primitives.Ints;
@@ -40,6 +41,7 @@
 import java.util.concurrent.locks.ReadWriteLock;
 import java.util.concurrent.locks.ReentrantLock;
 import java.util.concurrent.locks.ReentrantReadWriteLock;
+import org.checkerframework.checker.nullness.qual.Nullable;
 
 /**
  * A striped {@code Lock/Semaphore/ReadWriteLock}. This offers the underlying lock striping similar
@@ -82,6 +84,7 @@
  */
 @Beta
 @GwtIncompatible
+@ElementTypesAreNonnullByDefault
 public abstract class Striped<L> {
   /**
    * If there are at least this many stripes, we assume the memory usage of a ConcurrentMap will be
@@ -136,26 +139,26 @@ private Striped() {}
    * @return the stripes corresponding to the objects (one per each object, derived by delegating to
    *     {@link #get(Object)}; may contain duplicates), in an increasing index order.
    */
-  public Iterable<L> bulkGet(Iterable<?> keys) {
-    // Initially using the array to store the keys, then reusing it to store the respective L's
-    final Object[] array = Iterables.toArray(keys, Object.class);
-    if (array.length == 0) {
+  public Iterable<L> bulkGet(Iterable<? extends Object> keys) {
+    // Initially using the list to store the keys, then reusing it to store the respective L's
+    List<Object> result = newArrayList(keys);
+    if (result.isEmpty()) {
       return ImmutableList.of();
     }
-    int[] stripes = new int[array.length];
-    for (int i = 0; i < array.length; i++) {
-      stripes[i] = indexFor(array[i]);
+    int[] stripes = new int[result.size()];
+    for (int i = 0; i < result.size(); i++) {
+      stripes[i] = indexFor(result.get(i));
     }
     Arrays.sort(stripes);
     // optimize for runs of identical stripes
     int previousStripe = stripes[0];
-    array[0] = getAt(previousStripe);
-    for (int i = 1; i < array.length; i++) {
+    result.set(0, getAt(previousStripe));
+    for (int i = 1; i < result.size(); i++) {
       int currentStripe = stripes[i];
       if (currentStripe == previousStripe) {
-        array[i] = array[i - 1];
+        result.set(i, result.get(i - 1));
       } else {
-        array[i] = getAt(currentStripe);
+        result.set(i, getAt(currentStripe));
         previousStripe = currentStripe;
       }
     }
@@ -177,8 +180,8 @@ public Iterable<L> bulkGet(Iterable<?> keys) {
      * be garbage collected after locking them, ending up in a huge mess.
      */
     @SuppressWarnings("unchecked") // we carefully replaced all keys with their respective L's
-    List<L> asList = (List<L>) Arrays.asList(array);
-    return Collections.unmodifiableList(asList);
+    List<L> asStripes = (List<L>) result;
+    return Collections.unmodifiableList(asStripes);
   }
 
   // Static factories
@@ -203,14 +206,7 @@ static <L> Striped<L> custom(int stripes, Supplier<L> supplier) {
    * @return a new {@code Striped<Lock>}
    */
   public static Striped<Lock> lock(int stripes) {
-    return custom(
-        stripes,
-        new Supplier<Lock>() {
-          @Override
-          public Lock get() {
-            return new PaddedLock();
-          }
-        });
+    return custom(stripes, PaddedLock::new);
   }
 
   /**
@@ -221,14 +217,7 @@ public Lock get() {
    * @return a new {@code Striped<Lock>}
    */
   public static Striped<Lock> lazyWeakLock(int stripes) {
-    return lazy(
-        stripes,
-        new Supplier<Lock>() {
-          @Override
-          public Lock get() {
-            return new ReentrantLock(false);
-          }
-        });
+    return lazy(stripes, () -> new ReentrantLock(false));
   }
 
   private static <L> Striped<L> lazy(int stripes, Supplier<L> supplier) {
@@ -245,15 +234,8 @@ private static <L> Striped<L> lazy(int stripes, Supplier<L> supplier) {
    * @param permits the number of permits in each semaphore
    * @return a new {@code Striped<Semaphore>}
    */
-  public static Striped<Semaphore> semaphore(int stripes, final int permits) {
-    return custom(
-        stripes,
-        new Supplier<Semaphore>() {
-          @Override
-          public Semaphore get() {
-            return new PaddedSemaphore(permits);
-          }
-        });
+  public static Striped<Semaphore> semaphore(int stripes, int permits) {
+    return custom(stripes, () -> new PaddedSemaphore(permits));
   }
 
   /**
@@ -264,15 +246,8 @@ public Semaphore get() {
    * @param permits the number of permits in each semaphore
    * @return a new {@code Striped<Semaphore>}
    */
-  public static Striped<Semaphore> lazyWeakSemaphore(int stripes, final int permits) {
-    return lazy(
-        stripes,
-        new Supplier<Semaphore>() {
-          @Override
-          public Semaphore get() {
-            return new Semaphore(permits, false);
-          }
-        });
+  public static Striped<Semaphore> lazyWeakSemaphore(int stripes, int permits) {
+    return lazy(stripes, () -> new Semaphore(permits, false));
   }
 
   /**
@@ -283,7 +258,7 @@ public Semaphore get() {
    * @return a new {@code Striped<ReadWriteLock>}
    */
   public static Striped<ReadWriteLock> readWriteLock(int stripes) {
-    return custom(stripes, READ_WRITE_LOCK_SUPPLIER);
+    return custom(stripes, ReentrantReadWriteLock::new);
   }
 
   /**
@@ -294,25 +269,8 @@ public static Striped<ReadWriteLock> readWriteLock(int stripes) {
    * @return a new {@code Striped<ReadWriteLock>}
    */
   public static Striped<ReadWriteLock> lazyWeakReadWriteLock(int stripes) {
-    return lazy(stripes, WEAK_SAFE_READ_WRITE_LOCK_SUPPLIER);
+    return lazy(stripes, WeakSafeReadWriteLock::new);
   }
-
-  private static final Supplier<ReadWriteLock> READ_WRITE_LOCK_SUPPLIER =
-      new Supplier<ReadWriteLock>() {
-        @Override
-        public ReadWriteLock get() {
-          return new ReentrantReadWriteLock();
-        }
-      };
-
-  private static final Supplier<ReadWriteLock> WEAK_SAFE_READ_WRITE_LOCK_SUPPLIER =
-      new Supplier<ReadWriteLock>() {
-        @Override
-        public ReadWriteLock get() {
-          return new WeakSafeReadWriteLock();
-        }
-      };
-
   /**
    * ReadWriteLock implementation whose read and write locks retain a reference back to this lock.
    * Otherwise, a reference to just the read lock or just the write lock would not suffice to ensure
@@ -435,10 +393,10 @@ public int size() {
    */
   @VisibleForTesting
   static class SmallLazyStriped<L> extends PowerOfTwoStriped<L> {
-    final AtomicReferenceArray<ArrayReference<? extends L>> locks;
+    final AtomicReferenceArray<@Nullable ArrayReference<? extends L>> locks;
     final Supplier<L> supplier;
     final int size;
-    final ReferenceQueue<L> queue = new ReferenceQueue<L>();
+    final ReferenceQueue<L> queue = new ReferenceQueue<>();
 
     SmallLazyStriped(int stripes, Supplier<L> supplier) {
       super(stripes);
@@ -458,7 +416,7 @@ public L getAt(int index) {
         return existing;
       }
       L created = supplier.get();
-      ArrayReference<L> newRef = new ArrayReference<L>(created, index, queue);
+      ArrayReference<L> newRef = new ArrayReference<>(created, index, queue);
       while (!locks.compareAndSet(index, existingRef, newRef)) {
         // we raced, we need to re-read and try again
         existingRef = locks.get(index);
diff --git a/android/guava/src/com/google/common/util/concurrent/ThreadFactoryBuilder.java b/android/guava/src/com/google/common/util/concurrent/ThreadFactoryBuilder.java
index f09ed4e71721..091f56e799c0 100644
--- a/android/guava/src/com/google/common/util/concurrent/ThreadFactoryBuilder.java
+++ b/android/guava/src/com/google/common/util/concurrent/ThreadFactoryBuilder.java
@@ -16,6 +16,7 @@
 
 import static com.google.common.base.Preconditions.checkArgument;
 import static com.google.common.base.Preconditions.checkNotNull;
+import static java.util.Objects.requireNonNull;
 
 import com.google.common.annotations.GwtIncompatible;
 import com.google.errorprone.annotations.CanIgnoreReturnValue;
@@ -25,6 +26,7 @@
 import java.util.concurrent.Executors;
 import java.util.concurrent.ThreadFactory;
 import java.util.concurrent.atomic.AtomicLong;
+import javax.annotation.CheckForNull;
 
 /**
  * A ThreadFactory builder, providing any combination of these features:
@@ -45,12 +47,13 @@
  */
 @CanIgnoreReturnValue
 @GwtIncompatible
+@ElementTypesAreNonnullByDefault
 public final class ThreadFactoryBuilder {
-  private String nameFormat = null;
-  private Boolean daemon = null;
-  private Integer priority = null;
-  private UncaughtExceptionHandler uncaughtExceptionHandler = null;
-  private ThreadFactory backingThreadFactory = null;
+  @CheckForNull private String nameFormat = null;
+  @CheckForNull private Boolean daemon = null;
+  @CheckForNull private Integer priority = null;
+  @CheckForNull private UncaughtExceptionHandler uncaughtExceptionHandler = null;
+  @CheckForNull private ThreadFactory backingThreadFactory = null;
 
   /** Creates a new {@link ThreadFactory} builder. */
   public ThreadFactoryBuilder() {}
@@ -148,21 +151,22 @@ public ThreadFactory build() {
   // Split out so that the anonymous ThreadFactory can't contain a reference back to the builder.
   // At least, I assume that's why. TODO(cpovirk): Check, and maybe add a test for this.
   private static ThreadFactory doBuild(ThreadFactoryBuilder builder) {
-    final String nameFormat = builder.nameFormat;
-    final Boolean daemon = builder.daemon;
-    final Integer priority = builder.priority;
-    final UncaughtExceptionHandler uncaughtExceptionHandler = builder.uncaughtExceptionHandler;
-    final ThreadFactory backingThreadFactory =
+    String nameFormat = builder.nameFormat;
+    Boolean daemon = builder.daemon;
+    Integer priority = builder.priority;
+    UncaughtExceptionHandler uncaughtExceptionHandler = builder.uncaughtExceptionHandler;
+    ThreadFactory backingThreadFactory =
         (builder.backingThreadFactory != null)
             ? builder.backingThreadFactory
             : Executors.defaultThreadFactory();
-    final AtomicLong count = (nameFormat != null) ? new AtomicLong(0) : null;
+    AtomicLong count = (nameFormat != null) ? new AtomicLong(0) : null;
     return new ThreadFactory() {
       @Override
       public Thread newThread(Runnable runnable) {
         Thread thread = backingThreadFactory.newThread(runnable);
         if (nameFormat != null) {
-          thread.setName(format(nameFormat, count.getAndIncrement()));
+          // requireNonNull is safe because we create `count` if (and only if) we have a nameFormat.
+          thread.setName(format(nameFormat, requireNonNull(count).getAndIncrement()));
         }
         if (daemon != null) {
           thread.setDaemon(daemon);
diff --git a/android/guava/src/com/google/common/util/concurrent/TimeLimiter.java b/android/guava/src/com/google/common/util/concurrent/TimeLimiter.java
index b841517bc3ff..0883bccee0c1 100644
--- a/android/guava/src/com/google/common/util/concurrent/TimeLimiter.java
+++ b/android/guava/src/com/google/common/util/concurrent/TimeLimiter.java
@@ -22,6 +22,7 @@
 import java.util.concurrent.ExecutionException;
 import java.util.concurrent.TimeUnit;
 import java.util.concurrent.TimeoutException;
+import org.checkerframework.checker.nullness.qual.Nullable;
 
 /**
  * Imposes a time limit on method calls.
@@ -34,6 +35,7 @@
 @DoNotMock("Use FakeTimeLimiter")
 @GwtIncompatible
 @SuppressWarnings("GoodTime") // should have java.time.Duration overloads
+@ElementTypesAreNonnullByDefault
 public interface TimeLimiter {
 
   /**
@@ -97,7 +99,8 @@ public interface TimeLimiter {
    * @since 22.0
    */
   @CanIgnoreReturnValue
-  <T> T callWithTimeout(Callable<T> callable, long timeoutDuration, TimeUnit timeoutUnit)
+  <T extends @Nullable Object> T callWithTimeout(
+      Callable<T> callable, long timeoutDuration, TimeUnit timeoutUnit)
       throws TimeoutException, InterruptedException, ExecutionException;
 
   /**
@@ -120,7 +123,7 @@ <T> T callWithTimeout(Callable<T> callable, long timeoutDuration, TimeUnit timeo
    * @since 22.0
    */
   @CanIgnoreReturnValue
-  <T> T callUninterruptiblyWithTimeout(
+  <T extends @Nullable Object> T callUninterruptiblyWithTimeout(
       Callable<T> callable, long timeoutDuration, TimeUnit timeoutUnit)
       throws TimeoutException, ExecutionException;
 
diff --git a/android/guava/src/com/google/common/util/concurrent/TimeoutFuture.java b/android/guava/src/com/google/common/util/concurrent/TimeoutFuture.java
index a91bf67d103c..ed8a7bfdbe70 100644
--- a/android/guava/src/com/google/common/util/concurrent/TimeoutFuture.java
+++ b/android/guava/src/com/google/common/util/concurrent/TimeoutFuture.java
@@ -24,7 +24,8 @@
 import java.util.concurrent.ScheduledFuture;
 import java.util.concurrent.TimeUnit;
 import java.util.concurrent.TimeoutException;
-import org.checkerframework.checker.nullness.compatqual.NullableDecl;
+import javax.annotation.CheckForNull;
+import org.checkerframework.checker.nullness.qual.Nullable;
 
 /**
  * Implementation of {@code Futures#withTimeout}.
@@ -34,8 +35,9 @@
  * interrupted and cancelled if it times out.
  */
 @GwtIncompatible
-final class TimeoutFuture<V> extends FluentFuture.TrustedFuture<V> {
-  static <V> ListenableFuture<V> create(
+@ElementTypesAreNonnullByDefault
+final class TimeoutFuture<V extends @Nullable Object> extends FluentFuture.TrustedFuture<V> {
+  static <V extends @Nullable Object> ListenableFuture<V> create(
       ListenableFuture<V> delegate,
       long time,
       TimeUnit unit,
@@ -71,16 +73,16 @@ static <V> ListenableFuture<V> create(
    * write-barriers).
    */
 
-  @NullableDecl private ListenableFuture<V> delegateRef;
-  @NullableDecl private ScheduledFuture<?> timer;
+  @CheckForNull private ListenableFuture<V> delegateRef;
+  @CheckForNull private ScheduledFuture<?> timer;
 
   private TimeoutFuture(ListenableFuture<V> delegate) {
     this.delegateRef = Preconditions.checkNotNull(delegate);
   }
 
   /** A runnable that is called when the delegate or the timer completes. */
-  private static final class Fire<V> implements Runnable {
-    @NullableDecl TimeoutFuture<V> timeoutFutureRef;
+  private static final class Fire<V extends @Nullable Object> implements Runnable {
+    @CheckForNull TimeoutFuture<V> timeoutFutureRef;
 
     Fire(TimeoutFuture<V> timeoutFuture) {
       this.timeoutFutureRef = timeoutFuture;
@@ -152,13 +154,14 @@ public synchronized Throwable fillInStackTrace() {
   }
 
   @Override
+  @CheckForNull
   protected String pendingToString() {
     ListenableFuture<? extends V> localInputFuture = delegateRef;
     ScheduledFuture<?> localTimer = timer;
     if (localInputFuture != null) {
       String message = "inputFuture=[" + localInputFuture + "]";
       if (localTimer != null) {
-        final long delay = localTimer.getDelay(TimeUnit.MILLISECONDS);
+        long delay = localTimer.getDelay(TimeUnit.MILLISECONDS);
         // Negative delays look confusing in an error message
         if (delay > 0) {
           message += ", remaining delay=[" + delay + " ms]";
diff --git a/android/guava/src/com/google/common/util/concurrent/TrustedListenableFutureTask.java b/android/guava/src/com/google/common/util/concurrent/TrustedListenableFutureTask.java
index 3115502efcc8..929c9fb1ea23 100644
--- a/android/guava/src/com/google/common/util/concurrent/TrustedListenableFutureTask.java
+++ b/android/guava/src/com/google/common/util/concurrent/TrustedListenableFutureTask.java
@@ -21,7 +21,8 @@
 import java.util.concurrent.Callable;
 import java.util.concurrent.Executors;
 import java.util.concurrent.RunnableFuture;
-import org.checkerframework.checker.nullness.compatqual.NullableDecl;
+import javax.annotation.CheckForNull;
+import org.checkerframework.checker.nullness.qual.Nullable;
 
 /**
  * A {@link RunnableFuture} that also implements the {@link ListenableFuture} interface.
@@ -30,15 +31,17 @@
  * performance reasons.
  */
 @GwtCompatible
-class TrustedListenableFutureTask<V> extends FluentFuture.TrustedFuture<V>
+@ElementTypesAreNonnullByDefault
+class TrustedListenableFutureTask<V extends @Nullable Object> extends FluentFuture.TrustedFuture<V>
     implements RunnableFuture<V> {
 
-  static <V> TrustedListenableFutureTask<V> create(AsyncCallable<V> callable) {
-    return new TrustedListenableFutureTask<V>(callable);
+  static <V extends @Nullable Object> TrustedListenableFutureTask<V> create(
+      AsyncCallable<V> callable) {
+    return new TrustedListenableFutureTask<>(callable);
   }
 
-  static <V> TrustedListenableFutureTask<V> create(Callable<V> callable) {
-    return new TrustedListenableFutureTask<V>(callable);
+  static <V extends @Nullable Object> TrustedListenableFutureTask<V> create(Callable<V> callable) {
+    return new TrustedListenableFutureTask<>(callable);
   }
 
   /**
@@ -50,8 +53,9 @@ static <V> TrustedListenableFutureTask<V> create(Callable<V> callable) {
    *     result, consider using constructions of the form: {@code ListenableFuture<?> f =
    *     ListenableFutureTask.create(runnable, null)}
    */
-  static <V> TrustedListenableFutureTask<V> create(Runnable runnable, @NullableDecl V result) {
-    return new TrustedListenableFutureTask<V>(Executors.callable(runnable, result));
+  static <V extends @Nullable Object> TrustedListenableFutureTask<V> create(
+      Runnable runnable, @ParametricNullness V result) {
+    return new TrustedListenableFutureTask<>(Executors.callable(runnable, result));
   }
 
   /*
@@ -61,7 +65,7 @@ static <V> TrustedListenableFutureTask<V> create(Runnable runnable, @NullableDec
    * <p>{@code volatile} is required for j2objc transpiling:
    * https://developers.google.com/j2objc/guides/j2objc-memory-model#atomicity
    */
-  private volatile InterruptibleTask<?> task;
+  @CheckForNull private volatile InterruptibleTask<?> task;
 
   TrustedListenableFutureTask(Callable<V> callable) {
     this.task = new TrustedFutureInterruptibleTask(callable);
@@ -73,7 +77,7 @@ static <V> TrustedListenableFutureTask<V> create(Runnable runnable, @NullableDec
 
   @Override
   public void run() {
-    InterruptibleTask localTask = task;
+    InterruptibleTask<?> localTask = task;
     if (localTask != null) {
       localTask.run();
     }
@@ -89,7 +93,7 @@ protected void afterDone() {
     super.afterDone();
 
     if (wasInterrupted()) {
-      InterruptibleTask localTask = task;
+      InterruptibleTask<?> localTask = task;
       if (localTask != null) {
         localTask.interruptTask();
       }
@@ -99,8 +103,9 @@ protected void afterDone() {
   }
 
   @Override
+  @CheckForNull
   protected String pendingToString() {
-    InterruptibleTask localTask = task;
+    InterruptibleTask<?> localTask = task;
     if (localTask != null) {
       return "task=[" + localTask + "]";
     }
@@ -121,17 +126,19 @@ final boolean isDone() {
     }
 
     @Override
+    @ParametricNullness
     V runInterruptibly() throws Exception {
       return callable.call();
     }
 
     @Override
-    void afterRanInterruptibly(V result, Throwable error) {
-      if (error == null) {
-        TrustedListenableFutureTask.this.set(result);
-      } else {
-        setException(error);
-      }
+    void afterRanInterruptiblySuccess(@ParametricNullness V result) {
+      TrustedListenableFutureTask.this.set(result);
+    }
+
+    @Override
+    void afterRanInterruptiblyFailure(Throwable error) {
+      setException(error);
     }
 
     @Override
@@ -164,12 +171,13 @@ ListenableFuture<V> runInterruptibly() throws Exception {
     }
 
     @Override
-    void afterRanInterruptibly(ListenableFuture<V> result, Throwable error) {
-      if (error == null) {
-        setFuture(result);
-      } else {
-        setException(error);
-      }
+    void afterRanInterruptiblySuccess(ListenableFuture<V> result) {
+      setFuture(result);
+    }
+
+    @Override
+    void afterRanInterruptiblyFailure(Throwable error) {
+      setException(error);
     }
 
     @Override
diff --git a/android/guava/src/com/google/common/util/concurrent/UncaughtExceptionHandlers.java b/android/guava/src/com/google/common/util/concurrent/UncaughtExceptionHandlers.java
index c0c26006e1fd..a1add8bcbb30 100644
--- a/android/guava/src/com/google/common/util/concurrent/UncaughtExceptionHandlers.java
+++ b/android/guava/src/com/google/common/util/concurrent/UncaughtExceptionHandlers.java
@@ -29,6 +29,7 @@
  * @since 8.0
  */
 @GwtIncompatible
+@ElementTypesAreNonnullByDefault
 public final class UncaughtExceptionHandlers {
   private UncaughtExceptionHandlers() {}
 
diff --git a/android/guava/src/com/google/common/util/concurrent/UncheckedExecutionException.java b/android/guava/src/com/google/common/util/concurrent/UncheckedExecutionException.java
index 3dde73745f30..713f4a69e78d 100644
--- a/android/guava/src/com/google/common/util/concurrent/UncheckedExecutionException.java
+++ b/android/guava/src/com/google/common/util/concurrent/UncheckedExecutionException.java
@@ -15,7 +15,7 @@
 package com.google.common.util.concurrent;
 
 import com.google.common.annotations.GwtCompatible;
-import org.checkerframework.checker.nullness.compatqual.NullableDecl;
+import javax.annotation.CheckForNull;
 
 /**
  * Unchecked variant of {@link java.util.concurrent.ExecutionException}. As with {@code
@@ -33,22 +33,29 @@
  * @since 10.0
  */
 @GwtCompatible
+@ElementTypesAreNonnullByDefault
 public class UncheckedExecutionException extends RuntimeException {
+  /*
+   * Ideally, this class would have exposed only constructors that require a non-null cause. We
+   * might try to move in that direction, but there are complications. See
+   * https://github.com/jspecify/nullness-checker-for-checker-framework/blob/61aafa4ae52594830cfc2d61c8b113009dbdb045/src/main/java/com/google/jspecify/nullness/NullSpecTransfer.java#L789
+   */
+
   /** Creates a new instance with {@code null} as its detail message. */
   protected UncheckedExecutionException() {}
 
   /** Creates a new instance with the given detail message. */
-  protected UncheckedExecutionException(@NullableDecl String message) {
+  protected UncheckedExecutionException(@CheckForNull String message) {
     super(message);
   }
 
   /** Creates a new instance with the given detail message and cause. */
-  public UncheckedExecutionException(@NullableDecl String message, @NullableDecl Throwable cause) {
+  public UncheckedExecutionException(@CheckForNull String message, @CheckForNull Throwable cause) {
     super(message, cause);
   }
 
   /** Creates a new instance with the given cause. */
-  public UncheckedExecutionException(@NullableDecl Throwable cause) {
+  public UncheckedExecutionException(@CheckForNull Throwable cause) {
     super(cause);
   }
 
diff --git a/android/guava/src/com/google/common/util/concurrent/UncheckedTimeoutException.java b/android/guava/src/com/google/common/util/concurrent/UncheckedTimeoutException.java
index a09a97057f00..8e30fca37fd1 100644
--- a/android/guava/src/com/google/common/util/concurrent/UncheckedTimeoutException.java
+++ b/android/guava/src/com/google/common/util/concurrent/UncheckedTimeoutException.java
@@ -15,7 +15,7 @@
 package com.google.common.util.concurrent;
 
 import com.google.common.annotations.GwtIncompatible;
-import org.checkerframework.checker.nullness.compatqual.NullableDecl;
+import javax.annotation.CheckForNull;
 
 /**
  * Unchecked version of {@link java.util.concurrent.TimeoutException}.
@@ -24,18 +24,19 @@
  * @since 1.0
  */
 @GwtIncompatible
+@ElementTypesAreNonnullByDefault
 public class UncheckedTimeoutException extends RuntimeException {
   public UncheckedTimeoutException() {}
 
-  public UncheckedTimeoutException(@NullableDecl String message) {
+  public UncheckedTimeoutException(@CheckForNull String message) {
     super(message);
   }
 
-  public UncheckedTimeoutException(@NullableDecl Throwable cause) {
+  public UncheckedTimeoutException(@CheckForNull Throwable cause) {
     super(cause);
   }
 
-  public UncheckedTimeoutException(@NullableDecl String message, @NullableDecl Throwable cause) {
+  public UncheckedTimeoutException(@CheckForNull String message, @CheckForNull Throwable cause) {
     super(message, cause);
   }
 
diff --git a/android/guava/src/com/google/common/util/concurrent/Uninterruptibles.java b/android/guava/src/com/google/common/util/concurrent/Uninterruptibles.java
index 4f4678096221..c2c6f7ca86bc 100644
--- a/android/guava/src/com/google/common/util/concurrent/Uninterruptibles.java
+++ b/android/guava/src/com/google/common/util/concurrent/Uninterruptibles.java
@@ -17,7 +17,6 @@
 import static com.google.common.base.Verify.verify;
 import static java.util.concurrent.TimeUnit.NANOSECONDS;
 
-import com.google.common.annotations.Beta;
 import com.google.common.annotations.GwtCompatible;
 import com.google.common.annotations.GwtIncompatible;
 import com.google.common.base.Preconditions;
@@ -33,6 +32,7 @@
 import java.util.concurrent.TimeoutException;
 import java.util.concurrent.locks.Condition;
 import java.util.concurrent.locks.Lock;
+import org.checkerframework.checker.nullness.qual.Nullable;
 
 /**
  * Utilities for treating interruptible operations as uninterruptible. In all cases, if a thread is
@@ -43,6 +43,7 @@
  * @since 10.0
  */
 @GwtCompatible(emulated = true)
+@ElementTypesAreNonnullByDefault
 public final class Uninterruptibles {
 
   // Implementation Note: As of 3-7-11, the logic for each blocking/timeout
@@ -193,7 +194,9 @@ public static void joinUninterruptibly(Thread toJoin, long timeout, TimeUnit uni
    * @throws CancellationException if the computation was cancelled
    */
   @CanIgnoreReturnValue
-  public static <V> V getUninterruptibly(Future<V> future) throws ExecutionException {
+  @ParametricNullness
+  public static <V extends @Nullable Object> V getUninterruptibly(Future<V> future)
+      throws ExecutionException {
     boolean interrupted = false;
     try {
       while (true) {
@@ -231,8 +234,9 @@ public static <V> V getUninterruptibly(Future<V> future) throws ExecutionExcepti
   @CanIgnoreReturnValue
   @GwtIncompatible // TODO
   @SuppressWarnings("GoodTime") // should accept a java.time.Duration
-  public static <V> V getUninterruptibly(Future<V> future, long timeout, TimeUnit unit)
-      throws ExecutionException, TimeoutException {
+  @ParametricNullness
+  public static <V extends @Nullable Object> V getUninterruptibly(
+      Future<V> future, long timeout, TimeUnit unit) throws ExecutionException, TimeoutException {
     boolean interrupted = false;
     try {
       long remainingNanos = unit.toNanos(timeout);
@@ -405,7 +409,6 @@ public static boolean tryLockUninterruptibly(Lock lock, long timeout, TimeUnit u
    *
    * @since 30.0
    */
-  @Beta
   @GwtIncompatible // concurrency
   public static void awaitTerminationUninterruptibly(ExecutorService executor) {
     // TODO(cpovirk): We could optimize this to avoid calling nanoTime() at all.
@@ -418,7 +421,6 @@ public static void awaitTerminationUninterruptibly(ExecutorService executor) {
    *
    * @since 30.0
    */
-  @Beta
   @GwtIncompatible // concurrency
   @SuppressWarnings("GoodTime")
   public static boolean awaitTerminationUninterruptibly(
diff --git a/android/guava/src/com/google/common/util/concurrent/WrappingExecutorService.java b/android/guava/src/com/google/common/util/concurrent/WrappingExecutorService.java
index 217e0a770fee..5a3c3927a6b9 100644
--- a/android/guava/src/com/google/common/util/concurrent/WrappingExecutorService.java
+++ b/android/guava/src/com/google/common/util/concurrent/WrappingExecutorService.java
@@ -29,6 +29,7 @@
 import java.util.concurrent.Future;
 import java.util.concurrent.TimeUnit;
 import java.util.concurrent.TimeoutException;
+import org.checkerframework.checker.nullness.qual.Nullable;
 
 /**
  * An abstract {@code ExecutorService} that allows subclasses to {@linkplain #wrapTask(Callable)
@@ -42,6 +43,7 @@
  */
 @CanIgnoreReturnValue // TODO(cpovirk): Consider being more strict.
 @GwtIncompatible
+@ElementTypesAreNonnullByDefault
 abstract class WrappingExecutorService implements ExecutorService {
   private final ExecutorService delegate;
 
@@ -53,23 +55,20 @@ protected WrappingExecutorService(ExecutorService delegate) {
    * Wraps a {@code Callable} for submission to the underlying executor. This method is also applied
    * to any {@code Runnable} passed to the default implementation of {@link #wrapTask(Runnable)}.
    */
-  protected abstract <T> Callable<T> wrapTask(Callable<T> callable);
+  protected abstract <T extends @Nullable Object> Callable<T> wrapTask(Callable<T> callable);
 
   /**
    * Wraps a {@code Runnable} for submission to the underlying executor. The default implementation
    * delegates to {@link #wrapTask(Callable)}.
    */
   protected Runnable wrapTask(Runnable command) {
-    final Callable<Object> wrapped = wrapTask(Executors.callable(command, null));
-    return new Runnable() {
-      @Override
-      public void run() {
-        try {
-          wrapped.call();
-        } catch (Exception e) {
-          throwIfUnchecked(e);
-          throw new RuntimeException(e);
-        }
+    Callable<Object> wrapped = wrapTask(Executors.callable(command, null));
+    return () -> {
+      try {
+        wrapped.call();
+      } catch (Exception e) {
+        throwIfUnchecked(e);
+        throw new RuntimeException(e);
       }
     };
   }
@@ -79,7 +78,8 @@ public void run() {
    *
    * @throws NullPointerException if any element of {@code tasks} is null
    */
-  private <T> ImmutableList<Callable<T>> wrapTasks(Collection<? extends Callable<T>> tasks) {
+  private <T extends @Nullable Object> ImmutableList<Callable<T>> wrapTasks(
+      Collection<? extends Callable<T>> tasks) {
     ImmutableList.Builder<Callable<T>> builder = ImmutableList.builder();
     for (Callable<T> task : tasks) {
       builder.add(wrapTask(task));
@@ -94,7 +94,7 @@ public final void execute(Runnable command) {
   }
 
   @Override
-  public final <T> Future<T> submit(Callable<T> task) {
+  public final <T extends @Nullable Object> Future<T> submit(Callable<T> task) {
     return delegate.submit(wrapTask(checkNotNull(task)));
   }
 
@@ -104,31 +104,33 @@ public final Future<?> submit(Runnable task) {
   }
 
   @Override
-  public final <T> Future<T> submit(Runnable task, T result) {
+  public final <T extends @Nullable Object> Future<T> submit(
+      Runnable task, @ParametricNullness T result) {
     return delegate.submit(wrapTask(task), result);
   }
 
   @Override
-  public final <T> List<Future<T>> invokeAll(Collection<? extends Callable<T>> tasks)
-      throws InterruptedException {
+  public final <T extends @Nullable Object> List<Future<T>> invokeAll(
+      Collection<? extends Callable<T>> tasks) throws InterruptedException {
     return delegate.invokeAll(wrapTasks(tasks));
   }
 
   @Override
-  public final <T> List<Future<T>> invokeAll(
+  public final <T extends @Nullable Object> List<Future<T>> invokeAll(
       Collection<? extends Callable<T>> tasks, long timeout, TimeUnit unit)
       throws InterruptedException {
     return delegate.invokeAll(wrapTasks(tasks), timeout, unit);
   }
 
   @Override
-  public final <T> T invokeAny(Collection<? extends Callable<T>> tasks)
+  public final <T extends @Nullable Object> T invokeAny(Collection<? extends Callable<T>> tasks)
       throws InterruptedException, ExecutionException {
     return delegate.invokeAny(wrapTasks(tasks));
   }
 
   @Override
-  public final <T> T invokeAny(Collection<? extends Callable<T>> tasks, long timeout, TimeUnit unit)
+  public final <T extends @Nullable Object> T invokeAny(
+      Collection<? extends Callable<T>> tasks, long timeout, TimeUnit unit)
       throws InterruptedException, ExecutionException, TimeoutException {
     return delegate.invokeAny(wrapTasks(tasks), timeout, unit);
   }
diff --git a/android/guava/src/com/google/common/util/concurrent/WrappingScheduledExecutorService.java b/android/guava/src/com/google/common/util/concurrent/WrappingScheduledExecutorService.java
index 4ab700fde574..48f23c12c7cb 100644
--- a/android/guava/src/com/google/common/util/concurrent/WrappingScheduledExecutorService.java
+++ b/android/guava/src/com/google/common/util/concurrent/WrappingScheduledExecutorService.java
@@ -20,6 +20,7 @@
 import java.util.concurrent.ScheduledExecutorService;
 import java.util.concurrent.ScheduledFuture;
 import java.util.concurrent.TimeUnit;
+import org.checkerframework.checker.nullness.qual.Nullable;
 
 /**
  * An abstract {@code ScheduledExecutorService} that allows subclasses to {@linkplain
@@ -31,6 +32,7 @@
  */
 @CanIgnoreReturnValue // TODO(cpovirk): Consider being more strict.
 @GwtIncompatible
+@ElementTypesAreNonnullByDefault
 abstract class WrappingScheduledExecutorService extends WrappingExecutorService
     implements ScheduledExecutorService {
   final ScheduledExecutorService delegate;
@@ -46,7 +48,8 @@ public final ScheduledFuture<?> schedule(Runnable command, long delay, TimeUnit
   }
 
   @Override
-  public final <V> ScheduledFuture<V> schedule(Callable<V> task, long delay, TimeUnit unit) {
+  public final <V extends @Nullable Object> ScheduledFuture<V> schedule(
+      Callable<V> task, long delay, TimeUnit unit) {
     return delegate.schedule(wrapTask(task), delay, unit);
   }
 
diff --git a/android/guava/src/com/google/common/xml/ElementTypesAreNonnullByDefault.java b/android/guava/src/com/google/common/xml/ElementTypesAreNonnullByDefault.java
new file mode 100644
index 000000000000..b4fb4e3fe470
--- /dev/null
+++ b/android/guava/src/com/google/common/xml/ElementTypesAreNonnullByDefault.java
@@ -0,0 +1,41 @@
+/*
+ * Copyright (C) 2021 The Guava Authors
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package com.google.common.xml;
+
+import static java.lang.annotation.ElementType.FIELD;
+import static java.lang.annotation.ElementType.METHOD;
+import static java.lang.annotation.ElementType.PARAMETER;
+import static java.lang.annotation.ElementType.TYPE;
+import static java.lang.annotation.RetentionPolicy.RUNTIME;
+
+import com.google.common.annotations.GwtCompatible;
+import java.lang.annotation.Retention;
+import java.lang.annotation.Target;
+import javax.annotation.Nonnull;
+import javax.annotation.meta.TypeQualifierDefault;
+
+/**
+ * Marks all "top-level" types as non-null in a way that is recognized by Kotlin. Note that this
+ * unfortunately includes type-variable usages, so we also provide {@link ParametricNullness} to
+ * "undo" it as best we can.
+ */
+@GwtCompatible
+@Retention(RUNTIME)
+@Target(TYPE)
+@TypeQualifierDefault({FIELD, METHOD, PARAMETER})
+@Nonnull
+@interface ElementTypesAreNonnullByDefault {}
diff --git a/android/guava/src/com/google/common/xml/ParametricNullness.java b/android/guava/src/com/google/common/xml/ParametricNullness.java
new file mode 100644
index 000000000000..e4e5d12f0e3b
--- /dev/null
+++ b/android/guava/src/com/google/common/xml/ParametricNullness.java
@@ -0,0 +1,52 @@
+/*
+ * Copyright (C) 2021 The Guava Authors
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package com.google.common.xml;
+
+import static java.lang.annotation.ElementType.FIELD;
+import static java.lang.annotation.ElementType.METHOD;
+import static java.lang.annotation.ElementType.PARAMETER;
+import static java.lang.annotation.RetentionPolicy.RUNTIME;
+
+import com.google.common.annotations.GwtCompatible;
+import java.lang.annotation.Retention;
+import java.lang.annotation.Target;
+
+/**
+ * Marks a "top-level" type-variable usage as the closest we can get to "non-nullable when
+ * non-nullable; nullable when nullable" (like the Android <a
+ * href="https://android.googlesource.com/platform/libcore/+/master/luni/src/main/java/libcore/util/NullFromTypeParam.java">{@code
+ * NullFromTypeParam}</a>).
+ *
+ * <p>Consumers of this annotation include:
+ *
+ * <ul>
+ *   <li>Kotlin, for which it makes the type-variable usage (a) a Kotlin platform type when the type
+ *       argument is non-nullable and (b) nullable when the type argument is nullable. We use this
+ *       to "undo" {@link ElementTypesAreNonnullByDefault}.
+ *   <li><a href="https://developers.google.com/j2objc">J2ObjC</a>
+ *   <li>{@code NullPointerTester}, at least in the Android backport (where the type-use annotations
+ *       {@code NullPointerTester} would need are not available) and in case of <a
+ *       href="https://bugs.openjdk.java.net/browse/JDK-8202469">JDK-8202469</a>
+ * </ul>
+ *
+ */
+@GwtCompatible
+@Retention(RUNTIME)
+@Target({FIELD, METHOD, PARAMETER})
+@javax.annotation.meta.TypeQualifierNickname
+@javax.annotation.Nonnull(when = javax.annotation.meta.When.UNKNOWN)
+@interface ParametricNullness {}
diff --git a/android/guava/src/com/google/common/xml/XmlEscapers.java b/android/guava/src/com/google/common/xml/XmlEscapers.java
index a477217740da..33241f3f3299 100644
--- a/android/guava/src/com/google/common/xml/XmlEscapers.java
+++ b/android/guava/src/com/google/common/xml/XmlEscapers.java
@@ -14,7 +14,6 @@
 
 package com.google.common.xml;
 
-import com.google.common.annotations.Beta;
 import com.google.common.annotations.GwtCompatible;
 import com.google.common.escape.Escaper;
 import com.google.common.escape.Escapers;
@@ -38,8 +37,8 @@
  * @author David Beaumont
  * @since 15.0
  */
-@Beta
 @GwtCompatible
+@ElementTypesAreNonnullByDefault
 public class XmlEscapers {
   private XmlEscapers() {}
 
diff --git a/android/guava/src/com/google/thirdparty/publicsuffix/PublicSuffixPatterns.java b/android/guava/src/com/google/thirdparty/publicsuffix/PublicSuffixPatterns.java
index f091be78a0be..c987065e4647 100644
--- a/android/guava/src/com/google/thirdparty/publicsuffix/PublicSuffixPatterns.java
+++ b/android/guava/src/com/google/thirdparty/publicsuffix/PublicSuffixPatterns.java
@@ -30,7 +30,7 @@
  * determining whether a given domain name is an effective top-level domain (public suffix).
  *
  * <p>Because this class is used in GWT, the data members are stored in a space-efficient manner.
- * {@see TrieParser}.
+ * See {@link TrieParser}.
  *
  * @since 16.0
  */
@@ -42,7 +42,7 @@ private PublicSuffixPatterns() {}
   /** If a hostname is contained as a key in this map, it is a public suffix. */
   public static final ImmutableMap<String, PublicSuffixType> EXACT =
       TrieParser.parseTrie(
-          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+          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gro?lim?oc?pooc?ten?vog??n??t!.&a46oa0fz--nx?b&82wrzc--nx?ulc??emag?gro?l&im?ru,?moc!.reliamym,?t&en?opsgolb,?ude?v&di?og?ta0cu--nx??zibe?業商?織組?路網???z!.&ca?gro?lim?oc?vog????x&a!.&cm,eb,gg,s&e,u,?tac,ue,yx,?t??c!.&hta,ofni,vog???e&d&ef?nay??ma!nab??rof?s??ilften?jt?m!.&bog?gro?moc?t&en?opsgolb,?ude??g?ma2ibgy--nx??o&b!x??f?rex??rbgn--nx?s!.vog??x&am&jt?kt??x???y&4punu--nx?7rr03--nx?a&d!i&loh?rfkcalb??ot!.emyfilauqerp,??g?lp?p!ila??rot?ssin?wdaorb??b!.&duolcym,fo?hcetaidem,lim?moc!.topsgolb,?vog??ab?gur??c!.&ca?dtl?gro?lim?m&oc!.&ecrofelacs.j,topsgolb,??t??orp?s&egolke?serp??ten?vog?zib??amrahp?nega??d&dadog?uts??e&kcoh?ltneb?n&dys?om?rotta??snikcm??g!.&eb,gro?moc?oc?ten?ude?vog??olonhcet!.oc,?rene??hpargotohp?id?k!.&gro?moc?ten?ude??s??l!.&clp?d&em?i??gro?hcs?moc?ten?ude?vog??f?imaf!nacirema??l&a?il??ppus??m!.&eman?gro?lim?moc?t&en?opsgolb,?ude?vog?zib??edaca!.laiciffo,?ra??n&a&ffit?pmoc??os??o&j?s??p!.&gro?lim?moc?pooc?ten?ude?vog???r&e&corg?grus?llag?viled??lewej?otcerid?tnuoc?uxul??s!.&gro?lim?moc?ten?ude?vog??pil??t&efas?i&c?ledif?n&ifx?ummoc!.&bdnevar,gon,murofym,???r&ahc?uces??srevinu??laer?r&ap!.oby,?eporp??uaeb??u!.&bug?gro?lim?moc!.topsgolb,?ten?ude??b!tseb???van!dlo??xes??z&a!.&eman?gro?lim?moc?o&fni?rp??pp?t&en?ni??ude?vog?zib???b!.&az,gro?jsg,moc?ten?ude?vog???c!.&4e,inum.duolc.&rsu,tlf,?m&laer,urtnecatem.motsuc,?oc,topsgolb,??d!.&cos?gro?lop?m&oc?t??ossa?t&en?ra??ude?vog???ib!.&duolcsd,e&ht-rof,mos-rof,rom-rof,?izoj,nafamm,p&i&-on,fles,?ohbew,tfym,?retteb-rof,snd&nyd,uolc,?xro,?g??k!.&duolcj,gro?lim?moc?t&en?ropeletzak.saapu,?ude?vog???m!.&ca?gro?lim?oc?ten?ude?v&da?og????n!.&asq-irom--nx?ca?gro?htlaeh?i&r&c?o&am?ām???wi!k???keeg?l&im?oohcs??neg?oc!.topsgolb,?t&en?nemailrap?vog???a!niflla???rawhcs?s!.&ca?gro?oc???t!.&c&a?s??e&m?n??ibom?l&etoh?im??o&c?fni?g??ro?vt???u!.&gro?moc?oc?ten??rwon??yx!.&e&nozlacol,tisgolb,?gnitfarc,otpaz,??zub??λε?υε?авксом?брс!.&гро?до?ка?р&бо?п!у?????г&б?ро??дкм?зақ?итед?килотак?леб?мок?н&йално?ом??рку?сур!.&арамас,бпс,гро,зиб,ичос,ксм,м&ок,ырк,?рим,я,??тйас?фр?юе?յահ?לארשי?םוק?اي&روس?سيلم?ناتيروم??بر&ع?غملا??ة&كبش?ي&دوعسلا?روس??یدوعسلا??ت&ا&راما?لاصتا??را&ب?ڀ?ھب???ر&ئازجلا?ازاب?صم?طق??سنوت?عقوم?قارع?ك&تيب?يلوثاك??موك?ن&ا&تس&كاپ?کاپ??دوس?ر&يا?یا??مع?يلعلا??درالا?ميلا?ي&رحبلا?طسلف???ه&ارمه?يدوعسلا??وكمارا?يبظوبا?ۃیدوعسلا?टेन?त&राभ?ोराभ??नठगंस?मॉक?्मतराभ?ত&রাভ?ৰাভ??ালংাব?ਤਰਾਭ?તરાભ?ତରାଭ?ாயித்நஇ?ைக்ஙலஇ?்ரூப்பக்ஙிச?్తరాభ?ತರಾಭ?ംതരാഭ?ාකංල?มอค?ยทไ!.&จิกรุธ?ต็นเ?ร&ก์คงอ?าหท??ลาบฐัร?าษกึศ???ວາລ?ეგ?なんみ?アトス?トンイポ?ドウラク?ムコ?ル&グーグ?ーセ??ン&ゾマア?ョシッァフ??业企?东广?乐娱?亚基诺?你爱我?信中?务政?动移?博微?卦八?厅餐?司公?品食?善慈?团集?国中?國中?址网?坡加新?城商?尚时?山佛?店&商?网?酒大里嘉??府政?康健?息信?戏游?拉里格香?拿大?教主天?机手?构机!织组??标商?歌谷?浦利飞?港香!.&人個?司公?府政?絡網?織組?育教???湾台?灣&台?臺??物购?界世?益公?看点?科盈訊電?站网?籍書?线在?络网?网文中?聘招?販通?逊马亚?通联?里嘉?锡马淡?門澳?门澳?闻新?電家?국한?넷닷?성삼?컴닷??");
 
   /**
    * If a hostname is not a key in the EXCLUDE map, and if removing its leftmost component results
@@ -50,7 +50,7 @@ private PublicSuffixPatterns() {}
    */
   public static final ImmutableMap<String, PublicSuffixType> UNDER =
       TrieParser.parseTrie(
-          "ac.vedwa,d&b?uolc.&etiso&isnes,tnegam,?iaznab,rehcnar-no,scitats,??e&b.lrusnart,d.ecapsrebu,noz.notirt,t&atse.etupmoc,is.hsmroftalp,??gp?h&c.tenerif:.cvs,,k?trae.sppad:.zzb,,?k&c?f?nil.bewd,rowten.secla,u.hcs??ln.lrusnart,m&j?m?oc.&duolcmeaeboda.ved,edonil.recnalabedon,ico-remotsuc:.&ico,pco,sco,?,mme0,s&t&cejboedonil,nemelepiuq,?wanozama.&1-etupmoc,ble,etupmoc,??t&neyoj.snc,opsppa.r,???n&c.moc.swanozama.&ble,etupmoc,?ur.edoc,?o&c.pato,i.&duolciaznab.sdraykcab,elacsnoom,oir-no,reniatnoceruza,s&3k-no,olots,?xcq.sys,y5s,??p&j.&a&mahokoy?yogan??ebok?i&adnes?kasawak??oroppas?uhsuykatik??n?pa.knalfhtron,?r&b.mon?e??s&edoc.owo,w.rosivda,?t&a.&ofnistro.&nednuk,xe,?smcerutuf:.&ni,xe,?,?en.&cimonotpyrc,hvo.&gnitsoh,saapbew,???u&e.lrusnart,r.onijym.&gni&dnal,tsoh,?murtceps,spv,??ved.&erahbew,gts,lcl,yawetag,?z&c.murtnecatem.duolc,yx.tibelet,??");
+          "ac.vedwa,d&b?i.ym.ssr,uolc.&etiso&isnes,tnegam,?iaznab,rehcnar-no,scitats,??e&b.lrusnart,d.&ecapsrebu,yksurf,?noz.notirt,t&atse.etupmoc,is.&areduolc,hsmroftalp,tst,???g&oog.tnetnocresu,p??h&c.tenerif:.cvs,,k?trae.sppad:.zzb,,?k&c?f?nil.bewd,rowten.secla,u.hcs??ln.lrusnart,m&j?m?oc.&duolcmeaeboda.ved,edonil.recnalabedon,ico-remotsuc:.&ico,pco,sco,?,lrihwyap,mme0,osseccandcved,s&ecapsnaecolatigid,t&cejbo&edonil,rtluv,?nemelepiuq,?wanozama.&1-etupmoc,ble,etupmoc,??t&neyoj.snc,opsppa.r,???n&c.moc.swanozama.&ble,etupmoc,?ur.edoc,?o&c.pato,i.&duolciaznab.sdraykcab,elacsnoom,oir-no,reniatnoceruza,s&3k-no,olots,?xcq.sys,y5s,??p&j.&a&mahokoy?yogan??ebok?i&adnes?kasawak??oroppas?uhsuykatik??n?pa.&knalfhtron,repoleved,tegeb,??r&b.mon?e??s&edoc.owo,noitulos.rehid,w.rosivda,?t&a.&ofnistro.&nednuk,xe,?smcerutuf:.&ni,xe,?,?en.&cimonotpyrc,hvo.&gnitsoh,saapbew,???u&e.lrusnart,r.onijym.&gni&dnal,tsoh,?murtceps,spv,??ved.&e&gats&gts,lcl,?rahbew,?gts,lcl,yawetag,?z&c.murtnecatem.duolc,yx.tibelet,??");
 
   /**
    * The elements in this map would pass the UNDER test, but are known not to be public suffixes and
diff --git a/android/guava/src/com/google/thirdparty/publicsuffix/TrieParser.java b/android/guava/src/com/google/thirdparty/publicsuffix/TrieParser.java
index dd7778040ef2..89cdadd3da04 100644
--- a/android/guava/src/com/google/thirdparty/publicsuffix/TrieParser.java
+++ b/android/guava/src/com/google/thirdparty/publicsuffix/TrieParser.java
@@ -36,7 +36,7 @@ static ImmutableMap<String, PublicSuffixType> parseTrie(CharSequence encoded) {
     while (idx < encodedLen) {
       idx += doParseTrieToBuilder(Queues.<CharSequence>newArrayDeque(), encoded, idx, builder);
     }
-    return builder.build();
+    return builder.buildOrThrow();
   }
 
   /**
diff --git a/android/pom.xml b/android/pom.xml
index 0e0aa178afbe..40e437cebfd9 100644
--- a/android/pom.xml
+++ b/android/pom.xml
@@ -6,7 +6,7 @@
   <modelVersion>4.0.0</modelVersion>
   <groupId>com.google.guava</groupId>
   <artifactId>guava-parent</artifactId>
-  <version>HEAD-android-SNAPSHOT</version>
+  <version>31.1-android</version>
   <packaging>pom</packaging>
   <name>Guava Maven Parent</name>
   <description>Parent for guava artifacts</description>
@@ -14,27 +14,15 @@
   <properties>
     <!-- Override this with -Dtest.include="**/SomeTest.java" on the CLI -->
     <test.include>%regex[.*.class]</test.include>
-    <truth.version>1.1</truth.version>
-    <!--
-      Upgrading to 1.19 breaks things: Animal Sniffer reports a problem with the
-      use of ClassValue in FuturesGetChecked, even though we've added a
-      suppression annotation.
-
-      The problem might be
-      https://github.com/mojohaus/animal-sniffer/issues/131.
-
-      We could probably work around this with a different suppression strategy,
-      perhaps (untested):
-
-      <ignores><ignore>com.google.common.util.concurrent.FuturesGetChecked$GetCheckedTypeValidatorHolder$ClassValueValidator</ignore></ignores>
-
-      But upgrading doesn't really buy us much, as far as I know. (1.19 does
-      check test code in addition to prod code, but I don't think we care.)
-    -->
-    <animal.sniffer.version>1.18</animal.sniffer.version>
+    <truth.version>1.1.2</truth.version>
+    <checker-framework.version>3.32.0</checker-framework.version>
+    <animal.sniffer.version>1.20</animal.sniffer.version>
     <maven-javadoc-plugin.version>3.1.0</maven-javadoc-plugin.version>
+    <!-- Empty for all JDKs but 9-12 -->
+    <maven-javadoc-plugin.additionalJOptions></maven-javadoc-plugin.additionalJOptions>
     <maven-source-plugin.version>3.2.1</maven-source-plugin.version>
     <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
+    <test.add.opens></test.add.opens>
   </properties>
   <issueManagement>
     <system>GitHub Issues</system>
@@ -68,8 +56,8 @@
     </developer>
   </developers>
   <ciManagement>
-    <system>Travis CI</system>
-    <url>https://travis-ci.org/google/guava</url>
+    <system>GitHub Actions</system>
+    <url>https://github.com/google/guava/actions</url>
   </ciManagement>
   <modules>
     <module>guava</module>
@@ -132,8 +120,8 @@
           <artifactId>maven-compiler-plugin</artifactId>
           <version>3.8.1</version>
           <configuration>
-            <source>1.7</source>
-            <target>1.7</target>
+            <source>1.8</source>
+            <target>1.8</target>
             <compilerArgs>
               <!--
                    Make includes/excludes fully work:
@@ -166,13 +154,15 @@
           <artifactId>animal-sniffer-maven-plugin</artifactId>
           <version>${animal.sniffer.version}</version>
           <configuration>
-            <annotations>com.google.common.util.concurrent.IgnoreJRERequirement</annotations>
+            <checkTestClasses>true</checkTestClasses>
             <signature>
               <groupId>org.codehaus.mojo.signature</groupId>
               <artifactId>java16-sun</artifactId>
               <version>1.10</version>
             </signature>
             <ignores>
+              <!-- Allow requireNonNull: Android desugaring rewrites it (so it's safe for us to use), and it's useful for null checks. Note that this line allows *all* methods from java.util.Objects. That's the best that we can do with the configuration options that Animal Sniffer offers. -->
+              <ignore>java.util.Objects</ignore>
               <!-- Unsafe isn't part of the documented Java 6 API, but it is available.
                    And in cases where it's not, we have fallbacks. -->
               <ignore>sun.misc.Unsafe</ignore>
@@ -203,6 +193,7 @@
             </additionalOptions>
             <linksource>true</linksource>
             <source>8</source>
+            <additionalJOption>${maven-javadoc-plugin.additionalJOptions}</additionalJOption>
           </configuration>
           <executions>
             <execution>
@@ -240,7 +231,7 @@
             <runOrder>alphabetical</runOrder>
             <!-- Set max heap for tests. -->
             <!-- Catch dependencies on the default locale by setting it to hi-IN. -->
-            <argLine>-Xmx1536M -Duser.language=hi -Duser.country=IN</argLine>
+            <argLine>-Xmx1536M -Duser.language=hi -Duser.country=IN ${test.add.opens}</argLine>
           </configuration>
         </plugin>
         <plugin>
@@ -277,13 +268,24 @@
       </dependency>
       <dependency>
         <groupId>org.checkerframework</groupId>
-        <artifactId>checker-compat-qual</artifactId>
-        <version>2.5.5</version>
+        <artifactId>checker-qual</artifactId>
+        <version>${checker-framework.version}</version>
+      </dependency>
+      <dependency>
+        <groupId>org.checkerframework</groupId>
+        <artifactId>checker-util</artifactId>
+        <version>${checker-framework.version}</version>
+      </dependency>
+      <dependency>
+        <groupId>org.checkerframework</groupId>
+        <artifactId>checker-qual</artifactId>
+        <version>${checker-framework.version}</version>
+        <classifier>sources</classifier>
       </dependency>
       <dependency>
         <groupId>com.google.errorprone</groupId>
         <artifactId>error_prone_annotations</artifactId>
-        <version>2.5.1</version>
+        <version>2.11.0</version>
       </dependency>
       <dependency>
         <groupId>com.google.j2objc</groupId>
@@ -299,19 +301,19 @@
       <dependency>
         <groupId>org.easymock</groupId>
         <artifactId>easymock</artifactId>
-        <version>4.2</version>
+        <version>4.3</version>
         <scope>test</scope>
       </dependency>
       <dependency>
         <groupId>org.mockito</groupId>
         <artifactId>mockito-core</artifactId>
-        <version>3.6.28</version>
+        <version>3.9.0</version>
         <scope>test</scope>
       </dependency>
       <dependency>
         <groupId>com.google.jimfs</groupId>
         <artifactId>jimfs</artifactId>
-        <version>1.1</version>
+        <version>1.2</version>
         <scope>test</scope>
       </dependency>
       <dependency>
@@ -390,5 +392,45 @@
           </plugins>
       </build>
     </profile>
+    <profile>
+      <!--
+          Passes JDK 11-12-specific `no-module-directories` flag to Javadoc tool,
+          which is required to make symbol search work correctly in the generated
+          pages.
+
+          This flag does not exist on 9-10 and 13+ (https://bugs.openjdk.java.net/browse/JDK-8215582).
+
+          Consider removing it once our release and test scripts are migrated to a recent JDK (17+).
+       -->
+      <id>javadocs-jdk11-12</id>
+      <activation>
+        <jdk>[11,13)</jdk>
+      </activation>
+      <properties>
+        <maven-javadoc-plugin.additionalJOptions>--no-module-directories</maven-javadoc-plugin.additionalJOptions>
+      </properties>
+    </profile>
+    <profile>
+      <id>open-jre-modules</id>
+      <activation>
+        <jdk>[9,]</jdk>
+      </activation>
+      <properties>
+        <!--
+            Some tests need reflective access to the internals of these packages. It is only the
+            tests themselves and not the code being tested that needs that access, though there's no
+            obvious way to ensure that.
+
+            We could consider arranging things so that only the tests we know need this would get
+            the add-opens. Right now that doesn't seem worth the effort, though.
+        -->
+        <test.add.opens>
+          --add-opens java.base/java.lang=ALL-UNNAMED
+          --add-opens java.base/java.util=ALL-UNNAMED
+          --add-opens java.base/java.util.concurrent.locks=ALL-UNNAMED
+          --add-opens java.base/sun.security.jca=ALL-UNNAMED
+        </test.add.opens>
+      </properties>
+    </profile>
   </profiles>
 </project>
diff --git a/azure-pipelines.yml b/azure-pipelines.yml
index 86223ead9a35..dfafa385d564 100644
--- a/azure-pipelines.yml
+++ b/azure-pipelines.yml
@@ -13,7 +13,7 @@ jobs:
 - job: typecheck
   pool:
     vmImage: 'ubuntu-latest'
-  container: mdernst/cf-ubuntu-jdk8:latest
+  container: mdernst/cf-ubuntu-jdk17:latest
   strategy:
     matrix:
       formatterJob:
diff --git a/futures/listenablefuture1/src/com/google/common/util/concurrent/ListenableFuture.java b/futures/listenablefuture1/src/com/google/common/util/concurrent/ListenableFuture.java
index 98e31ed37466..a8d9dd4de5f9 100644
--- a/futures/listenablefuture1/src/com/google/common/util/concurrent/ListenableFuture.java
+++ b/futures/listenablefuture1/src/com/google/common/util/concurrent/ListenableFuture.java
@@ -18,6 +18,7 @@
 import java.util.concurrent.Executor;
 import java.util.concurrent.Future;
 import java.util.concurrent.RejectedExecutionException;
+import org.checkerframework.checker.nullness.qual.Nullable;
 
 /**
  * A {@link Future} that accepts completion listeners. Each listener has an associated executor, and
@@ -99,8 +100,24 @@
  * @author Nishant Thakkar
  * @since 1.0
  */
+/*
+ * Some of the annotations below were added after we released our separate
+ * com.google.guava:listenablefuture:1.0 artifact. (For more on that artifact, see
+ * https://github.com/google/guava/releases/tag/v27.0) This means that the copy of ListenableFuture
+ * in com.google.guava:guava differs from the "frozen" copy in the listenablefuture artifact. This
+ * could in principle cause problems for some users. Still, we expect that the benefits of the
+ * nullness annotations in particular will outweigh the costs. (And it's worth noting that we have
+ * released multiple ListenableFuture.class files that are not byte-for-byte compatible even from
+ * the beginning, thanks to using different `-source -target` values for compiling our `-jre` and
+ * `-android` "flavors.")
+ *
+ * (We could consider releasing a listenablefuture:1.0.1 someday. But we would want to look into how
+ * that affects users, especially users of the Android Gradle Plugin, since the plugin developers
+ * put in a special hack for us: https://issuetracker.google.com/issues/131431257)
+ */
 @DoNotMock("Use the methods in Futures (like immediateFuture) or SettableFuture")
-public interface ListenableFuture<V> extends Future<V> {
+@ElementTypesAreNonnullByDefault
+public interface ListenableFuture<V extends @Nullable Object> extends Future<V> {
   /**
    * Registers a listener to be {@linkplain Executor#execute(Runnable) run} on the given executor.
    * The listener will run when the {@code Future}'s computation is {@linkplain Future#isDone()
diff --git a/guava-bom/pom.xml b/guava-bom/pom.xml
index ea321802a08d..1a3d98ec49b8 100644
--- a/guava-bom/pom.xml
+++ b/guava-bom/pom.xml
@@ -8,7 +8,7 @@
 
   <groupId>com.google.guava</groupId>
   <artifactId>guava-bom</artifactId>
-  <version>30.1.1-jre</version>
+  <version>31.1-jre</version>
   <packaging>pom</packaging>
   
   <parent>
diff --git a/guava-gwt/pom.xml b/guava-gwt/pom.xml
index fe62a3a6ffaa..f392a31e0192 100644
--- a/guava-gwt/pom.xml
+++ b/guava-gwt/pom.xml
@@ -5,7 +5,7 @@
   <parent>
     <groupId>com.google.guava</groupId>
     <artifactId>guava-parent</artifactId>
-    <version>30.1.1-jre</version>
+    <version>31.1-jre</version>
   </parent>
   <artifactId>guava-gwt</artifactId>
   <name>Guava GWT compatible libs</name>
@@ -304,6 +304,12 @@
                     <contains text="@GwtCompatible"/>
                   </fileset>
                 </copy>
+                <replace token="@Nullable" value="">
+                  <fileset dir="${project.build.directory}">
+                    <include name="guava-gwt-sources/**/*.java"/>
+                    <include name="guava-test-gwt-sources/**/*.java"/>
+                  </fileset>
+                </replace>
               </target>
             </configuration>
           </execution>
diff --git a/guava-gwt/src-super/com/google/common/cache/super/com/google/common/cache/LocalCache.java b/guava-gwt/src-super/com/google/common/cache/super/com/google/common/cache/LocalCache.java
index dba29ff61c77..8530defd2e6c 100644
--- a/guava-gwt/src-super/com/google/common/cache/super/com/google/common/cache/LocalCache.java
+++ b/guava-gwt/src-super/com/google/common/cache/super/com/google/common/cache/LocalCache.java
@@ -550,7 +550,7 @@ class EntryIterator implements Iterator<Entry<K, V>> {
     @Override
     public Entry<K, V> next() {
       if (nextEntry == null) {
-        hasNext();
+        boolean unused = hasNext();
 
         if (nextEntry == null) {
           throw new NoSuchElementException();
diff --git a/guava-gwt/src-super/com/google/common/collect/super/com/google/common/collect/ForwardingImmutableMap.java b/guava-gwt/src-super/com/google/common/collect/super/com/google/common/collect/ForwardingImmutableMap.java
index 68cce933d4d8..e3dd7032c279 100644
--- a/guava-gwt/src-super/com/google/common/collect/super/com/google/common/collect/ForwardingImmutableMap.java
+++ b/guava-gwt/src-super/com/google/common/collect/super/com/google/common/collect/ForwardingImmutableMap.java
@@ -37,12 +37,12 @@ public abstract class ForwardingImmutableMap<K, V> extends ImmutableMap<K, V> {
   }
 
   @SuppressWarnings("unchecked")
-  ForwardingImmutableMap(Entry<? extends K, ? extends V>... entries) {
+  ForwardingImmutableMap(boolean throwIfDuplicateKeys, Entry<? extends K, ? extends V>... entries) {
     Map<K, V> delegate = Maps.newLinkedHashMap();
     for (Entry<? extends K, ? extends V> entry : entries) {
       K key = checkNotNull(entry.getKey());
       V previous = delegate.put(key, checkNotNull(entry.getValue()));
-      if (previous != null) {
+      if (throwIfDuplicateKeys && previous != null) {
         throw new IllegalArgumentException("duplicate key: " + key);
       }
     }
diff --git a/guava-gwt/src-super/com/google/common/collect/super/com/google/common/collect/ImmutableBiMap.java b/guava-gwt/src-super/com/google/common/collect/super/com/google/common/collect/ImmutableBiMap.java
index 8236f00c0509..ff989657fa76 100644
--- a/guava-gwt/src-super/com/google/common/collect/super/com/google/common/collect/ImmutableBiMap.java
+++ b/guava-gwt/src-super/com/google/common/collect/super/com/google/common/collect/ImmutableBiMap.java
@@ -65,6 +65,93 @@ public static <K, V> ImmutableBiMap<K, V> of(
     return new RegularImmutableBiMap<K, V>(ImmutableMap.of(k1, v1, k2, v2, k3, v3, k4, v4, k5, v5));
   }
 
+  public static <K, V> ImmutableBiMap<K, V> of(
+      K k1, V v1, K k2, V v2, K k3, V v3, K k4, V v4, K k5, V v5, K k6, V v6) {
+    return new RegularImmutableBiMap<K, V>(
+        ImmutableMap.of(k1, v1, k2, v2, k3, v3, k4, v4, k5, v5, k6, v6));
+  }
+
+  public static <K, V> ImmutableBiMap<K, V> of(
+      K k1, V v1, K k2, V v2, K k3, V v3, K k4, V v4, K k5, V v5, K k6, V v6, K k7, V v7) {
+    return new RegularImmutableBiMap<K, V>(
+        ImmutableMap.of(k1, v1, k2, v2, k3, v3, k4, v4, k5, v5, k6, v6, k7, v7));
+  }
+
+  public static <K, V> ImmutableBiMap<K, V> of(
+      K k1,
+      V v1,
+      K k2,
+      V v2,
+      K k3,
+      V v3,
+      K k4,
+      V v4,
+      K k5,
+      V v5,
+      K k6,
+      V v6,
+      K k7,
+      V v7,
+      K k8,
+      V v8) {
+    return new RegularImmutableBiMap<K, V>(
+        ImmutableMap.of(k1, v1, k2, v2, k3, v3, k4, v4, k5, v5, k6, v6, k7, v7, k8, v8));
+  }
+
+  public static <K, V> ImmutableBiMap<K, V> of(
+      K k1,
+      V v1,
+      K k2,
+      V v2,
+      K k3,
+      V v3,
+      K k4,
+      V v4,
+      K k5,
+      V v5,
+      K k6,
+      V v6,
+      K k7,
+      V v7,
+      K k8,
+      V v8,
+      K k9,
+      V v9) {
+    return new RegularImmutableBiMap<K, V>(
+        ImmutableMap.of(k1, v1, k2, v2, k3, v3, k4, v4, k5, v5, k6, v6, k7, v7, k8, v8, k9, v9));
+  }
+
+  public static <K, V> ImmutableBiMap<K, V> of(
+      K k1,
+      V v1,
+      K k2,
+      V v2,
+      K k3,
+      V v3,
+      K k4,
+      V v4,
+      K k5,
+      V v5,
+      K k6,
+      V v6,
+      K k7,
+      V v7,
+      K k8,
+      V v8,
+      K k9,
+      V v9,
+      K k10,
+      V v10) {
+    return new RegularImmutableBiMap<K, V>(
+        ImmutableMap.of(
+            k1, v1, k2, v2, k3, v3, k4, v4, k5, v5, k6, v6, k7, v7, k8, v8, k9, v9, k10, v10));
+  }
+
+  @SafeVarargs
+  public static <K, V> ImmutableBiMap<K, V> ofEntries(Entry<? extends K, ? extends V>... entries) {
+    return new RegularImmutableBiMap<K, V>(ImmutableMap.ofEntries(entries));
+  }
+
   public static <K, V> Builder<K, V> builder() {
     return new Builder<K, V>();
   }
@@ -113,11 +200,16 @@ Builder<K, V> combine(Builder<K, V> other) {
 
     @Override
     public ImmutableBiMap<K, V> build() {
-      ImmutableMap<K, V> map = super.build();
+      return buildOrThrow();
+    }
+
+    @Override
+    public ImmutableBiMap<K, V> buildOrThrow() {
+      ImmutableMap<K, V> map = super.buildOrThrow();
       if (map.isEmpty()) {
         return of();
       }
-      return new RegularImmutableBiMap<K, V>(super.build());
+      return new RegularImmutableBiMap<K, V>(super.buildOrThrow());
     }
 
     @Override
diff --git a/guava-gwt/src-super/com/google/common/collect/super/com/google/common/collect/ImmutableMap.java b/guava-gwt/src-super/com/google/common/collect/super/com/google/common/collect/ImmutableMap.java
index 550b7d1c3e78..f0b15f6b5165 100644
--- a/guava-gwt/src-super/com/google/common/collect/super/com/google/common/collect/ImmutableMap.java
+++ b/guava-gwt/src-super/com/google/common/collect/super/com/google/common/collect/ImmutableMap.java
@@ -117,7 +117,128 @@ public static <K, V> ImmutableMap<K, V> of(
         entryOf(k1, v1), entryOf(k2, v2), entryOf(k3, v3), entryOf(k4, v4), entryOf(k5, v5));
   }
 
-  // looking for of() with > 5 entries? Use the builder instead.
+  public static <K, V> ImmutableMap<K, V> of(
+      K k1, V v1, K k2, V v2, K k3, V v3, K k4, V v4, K k5, V v5, K k6, V v6) {
+    return new RegularImmutableMap<K, V>(
+        entryOf(k1, v1),
+        entryOf(k2, v2),
+        entryOf(k3, v3),
+        entryOf(k4, v4),
+        entryOf(k5, v5),
+        entryOf(k6, v6));
+  }
+
+  public static <K, V> ImmutableMap<K, V> of(
+      K k1, V v1, K k2, V v2, K k3, V v3, K k4, V v4, K k5, V v5, K k6, V v6, K k7, V v7) {
+    return new RegularImmutableMap<K, V>(
+        entryOf(k1, v1),
+        entryOf(k2, v2),
+        entryOf(k3, v3),
+        entryOf(k4, v4),
+        entryOf(k5, v5),
+        entryOf(k6, v6),
+        entryOf(k7, v7));
+  }
+
+  public static <K, V> ImmutableMap<K, V> of(
+      K k1,
+      V v1,
+      K k2,
+      V v2,
+      K k3,
+      V v3,
+      K k4,
+      V v4,
+      K k5,
+      V v5,
+      K k6,
+      V v6,
+      K k7,
+      V v7,
+      K k8,
+      V v8) {
+    return new RegularImmutableMap<K, V>(
+        entryOf(k1, v1),
+        entryOf(k2, v2),
+        entryOf(k3, v3),
+        entryOf(k4, v4),
+        entryOf(k5, v5),
+        entryOf(k6, v6),
+        entryOf(k7, v7),
+        entryOf(k8, v8));
+  }
+
+  public static <K, V> ImmutableMap<K, V> of(
+      K k1,
+      V v1,
+      K k2,
+      V v2,
+      K k3,
+      V v3,
+      K k4,
+      V v4,
+      K k5,
+      V v5,
+      K k6,
+      V v6,
+      K k7,
+      V v7,
+      K k8,
+      V v8,
+      K k9,
+      V v9) {
+    return new RegularImmutableMap<K, V>(
+        entryOf(k1, v1),
+        entryOf(k2, v2),
+        entryOf(k3, v3),
+        entryOf(k4, v4),
+        entryOf(k5, v5),
+        entryOf(k6, v6),
+        entryOf(k7, v7),
+        entryOf(k8, v8),
+        entryOf(k9, v9));
+  }
+
+  public static <K, V> ImmutableMap<K, V> of(
+      K k1,
+      V v1,
+      K k2,
+      V v2,
+      K k3,
+      V v3,
+      K k4,
+      V v4,
+      K k5,
+      V v5,
+      K k6,
+      V v6,
+      K k7,
+      V v7,
+      K k8,
+      V v8,
+      K k9,
+      V v9,
+      K k10,
+      V v10) {
+    return new RegularImmutableMap<K, V>(
+        entryOf(k1, v1),
+        entryOf(k2, v2),
+        entryOf(k3, v3),
+        entryOf(k4, v4),
+        entryOf(k5, v5),
+        entryOf(k6, v6),
+        entryOf(k7, v7),
+        entryOf(k8, v8),
+        entryOf(k9, v9),
+        entryOf(k10, v10));
+  }
+
+  // looking for of() with > 10 entries? Use the builder instead.
+
+  @SafeVarargs
+  public static <K, V> ImmutableMap<K, V> ofEntries(Entry<? extends K, ? extends V>... entries) {
+    return new RegularImmutableMap(entries);
+  }
 
   public static <K, V> Builder<K, V> builder() {
     return new Builder<K, V>();
@@ -186,11 +307,28 @@ Builder<K, V> combine(Builder<K, V> other) {
     }
 
     public ImmutableMap<K, V> build() {
+      return buildOrThrow();
+    }
+
+    private ImmutableMap<K, V> build(boolean throwIfDuplicateKeys) {
       if (valueComparator != null) {
         Collections.sort(
             entries, Ordering.from(valueComparator).onResultOf(Maps.<V>valueFunction()));
       }
-      return fromEntryList(entries);
+      return fromEntryList(throwIfDuplicateKeys, entries);
+    }
+
+    public ImmutableMap<K, V> buildOrThrow() {
+      return build(/* throwIfDuplicateKeys= */ true);
+    }
+
+    public ImmutableMap<K, V> buildKeepingLast() {
+      if (valueComparator != null) {
+        // Probably not worth supporting this in GWT
+        throw new UnsupportedOperationException(
+            "orderEntriesByValue + buildKeepingLast not supported under GWT");
+      }
+      return build(/* throwIfDuplicateKeys= */ false);
     }
 
     ImmutableMap<K, V> buildJdkBacked() {
@@ -198,8 +336,13 @@ ImmutableMap<K, V> buildJdkBacked() {
     }
   }
 
-  static <K, V> ImmutableMap<K, V> fromEntryList(
+  private static <K, V> ImmutableMap<K, V> fromEntryList(
       Collection<? extends Entry<? extends K, ? extends V>> entries) {
+    return fromEntryList(/* throwIfDuplicateKeys= */ true, entries);
+  }
+
+  private static <K, V> ImmutableMap<K, V> fromEntryList(
+      boolean throwIfDuplicateKeys, Collection<? extends Entry<? extends K, ? extends V>> entries) {
     int size = entries.size();
     switch (size) {
       case 0:
@@ -210,7 +353,7 @@ static <K, V> ImmutableMap<K, V> fromEntryList(
       default:
         @SuppressWarnings("unchecked")
         Entry<K, V>[] entryArray = entries.toArray(new Entry[entries.size()]);
-        return new RegularImmutableMap<K, V>(entryArray);
+        return new RegularImmutableMap<K, V>(throwIfDuplicateKeys, entryArray);
     }
   }
 
diff --git a/guava-gwt/src-super/com/google/common/collect/super/com/google/common/collect/ImmutableSet.java b/guava-gwt/src-super/com/google/common/collect/super/com/google/common/collect/ImmutableSet.java
index 6d4b800a0728..d5a8dad545b9 100644
--- a/guava-gwt/src-super/com/google/common/collect/super/com/google/common/collect/ImmutableSet.java
+++ b/guava-gwt/src-super/com/google/common/collect/super/com/google/common/collect/ImmutableSet.java
@@ -18,6 +18,7 @@
 
 import static com.google.common.base.Preconditions.checkNotNull;
 
+import com.google.errorprone.annotations.concurrent.LazyInit;
 import java.util.ArrayList;
 import java.util.Collection;
 import java.util.Collections;
@@ -174,6 +175,24 @@ public int hashCode() {
   @Override
   public abstract UnmodifiableIterator<E> iterator();
 
+  abstract static class CachingAsList<E> extends ImmutableSet<E> {
+    @LazyInit private transient ImmutableList<E> asList;
+
+    @Override
+    public ImmutableList<E> asList() {
+      ImmutableList<E> result = asList;
+      if (result == null) {
+        return asList = createAsList();
+      } else {
+        return result;
+      }
+    }
+
+    ImmutableList<E> createAsList() {
+      return new RegularImmutableAsList<E>(this, toArray());
+    }
+  }
+
   abstract static class Indexed<E> extends ImmutableSet<E> {
     abstract E get(int index);
 
diff --git a/guava-gwt/src-super/com/google/common/collect/super/com/google/common/collect/ImmutableSortedMap.java b/guava-gwt/src-super/com/google/common/collect/super/com/google/common/collect/ImmutableSortedMap.java
index d255c35490c5..fb626be42eaf 100644
--- a/guava-gwt/src-super/com/google/common/collect/super/com/google/common/collect/ImmutableSortedMap.java
+++ b/guava-gwt/src-super/com/google/common/collect/super/com/google/common/collect/ImmutableSortedMap.java
@@ -129,6 +129,127 @@ public static <K extends Comparable<? super K>, V> ImmutableSortedMap<K, V> of(
         .build();
   }
 
+  public static <K extends Comparable<? super K>, V> ImmutableSortedMap<K, V> of(
+      K k1, V v1, K k2, V v2, K k3, V v3, K k4, V v4, K k5, V v5, K k6, V v6) {
+    return new Builder<K, V>(Ordering.natural())
+        .put(k1, v1)
+        .put(k2, v2)
+        .put(k3, v3)
+        .put(k4, v4)
+        .put(k5, v5)
+        .put(k6, v6)
+        .build();
+  }
+
+  public static <K extends Comparable<? super K>, V> ImmutableSortedMap<K, V> of(
+      K k1, V v1, K k2, V v2, K k3, V v3, K k4, V v4, K k5, V v5, K k6, V v6, K k7, V v7) {
+    return new Builder<K, V>(Ordering.natural())
+        .put(k1, v1)
+        .put(k2, v2)
+        .put(k3, v3)
+        .put(k4, v4)
+        .put(k5, v5)
+        .put(k6, v6)
+        .put(k7, v7)
+        .build();
+  }
+
+  public static <K extends Comparable<? super K>, V> ImmutableSortedMap<K, V> of(
+      K k1,
+      V v1,
+      K k2,
+      V v2,
+      K k3,
+      V v3,
+      K k4,
+      V v4,
+      K k5,
+      V v5,
+      K k6,
+      V v6,
+      K k7,
+      V v7,
+      K k8,
+      V v8) {
+    return new Builder<K, V>(Ordering.natural())
+        .put(k1, v1)
+        .put(k2, v2)
+        .put(k3, v3)
+        .put(k4, v4)
+        .put(k5, v5)
+        .put(k6, v6)
+        .put(k7, v7)
+        .put(k8, v8)
+        .build();
+  }
+
+  public static <K extends Comparable<? super K>, V> ImmutableSortedMap<K, V> of(
+      K k1,
+      V v1,
+      K k2,
+      V v2,
+      K k3,
+      V v3,
+      K k4,
+      V v4,
+      K k5,
+      V v5,
+      K k6,
+      V v6,
+      K k7,
+      V v7,
+      K k8,
+      V v8,
+      K k9,
+      V v9) {
+    return new Builder<K, V>(Ordering.natural())
+        .put(k1, v1)
+        .put(k2, v2)
+        .put(k3, v3)
+        .put(k4, v4)
+        .put(k5, v5)
+        .put(k6, v6)
+        .put(k7, v7)
+        .put(k8, v8)
+        .put(k9, v9)
+        .build();
+  }
+
+  public static <K extends Comparable<? super K>, V> ImmutableSortedMap<K, V> of(
+      K k1,
+      V v1,
+      K k2,
+      V v2,
+      K k3,
+      V v3,
+      K k4,
+      V v4,
+      K k5,
+      V v5,
+      K k6,
+      V v6,
+      K k7,
+      V v7,
+      K k8,
+      V v8,
+      K k9,
+      V v9,
+      K k10,
+      V v10) {
+    return new Builder<K, V>(Ordering.natural())
+        .put(k1, v1)
+        .put(k2, v2)
+        .put(k3, v3)
+        .put(k4, v4)
+        .put(k5, v5)
+        .put(k6, v6)
+        .put(k7, v7)
+        .put(k8, v8)
+        .put(k9, v9)
+        .put(k10, v10)
+        .build();
+  }
+
   public static <K, V> ImmutableSortedMap<K, V> copyOf(Map<? extends K, ? extends V> map) {
     return copyOfInternal((Map) map, (Ordering<K>) Ordering.natural());
   }
@@ -258,6 +379,11 @@ public Builder<K, V> orderEntriesByValue(Comparator<? super V> valueComparator)
 
     @Override
     public ImmutableSortedMap<K, V> build() {
+      return buildOrThrow();
+    }
+
+    @Override
+    public ImmutableSortedMap<K, V> buildOrThrow() {
       SortedMap<K, V> delegate = newModifiableDelegate(comparator);
       for (Entry<? extends K, ? extends V> entry : entries) {
         putEntryWithChecks(delegate, entry);
diff --git a/guava-gwt/src-super/com/google/common/collect/super/com/google/common/collect/Platform.java b/guava-gwt/src-super/com/google/common/collect/super/com/google/common/collect/Platform.java
index bb9fc16be44b..4b85849acdb4 100644
--- a/guava-gwt/src-super/com/google/common/collect/super/com/google/common/collect/Platform.java
+++ b/guava-gwt/src-super/com/google/common/collect/super/com/google/common/collect/Platform.java
@@ -17,8 +17,10 @@
 package com.google.common.collect;
 
 import java.util.Arrays;
+import java.util.Collections;
 import java.util.Map;
 import java.util.Set;
+import java.util.concurrent.ConcurrentHashMap;
 import jsinterop.annotations.JsPackage;
 import jsinterop.annotations.JsProperty;
 import jsinterop.annotations.JsType;
@@ -43,6 +45,14 @@ static <E> Set<E> newHashSetWithExpectedSize(int expectedSize) {
     return Sets.newHashSetWithExpectedSize(expectedSize);
   }
 
+  static <E> Set<E> newConcurrentHashSet() {
+    // GWT's ConcurrentHashMap is a wrapper around HashMap, but it rejects null keys, which matches
+    // the behaviour of the non-GWT implementation of newConcurrentHashSet().
+    // On the other hand HashSet might be better for code size if apps aren't
+    // already using Collections.newSetFromMap and ConcurrentHashMap.
+    return Collections.newSetFromMap(new ConcurrentHashMap<E, Boolean>());
+  }
+
   static <E> Set<E> newLinkedHashSetWithExpectedSize(int expectedSize) {
     return Sets.newLinkedHashSetWithExpectedSize(expectedSize);
   }
diff --git a/guava-gwt/src-super/com/google/common/collect/super/com/google/common/collect/RegularImmutableMap.java b/guava-gwt/src-super/com/google/common/collect/super/com/google/common/collect/RegularImmutableMap.java
index b79ce805ea52..988537114934 100644
--- a/guava-gwt/src-super/com/google/common/collect/super/com/google/common/collect/RegularImmutableMap.java
+++ b/guava-gwt/src-super/com/google/common/collect/super/com/google/common/collect/RegularImmutableMap.java
@@ -30,6 +30,10 @@ final class RegularImmutableMap<K, V> extends ForwardingImmutableMap<K, V> {
   }
 
   RegularImmutableMap(Entry<? extends K, ? extends V>... entries) {
-    super(entries);
+    this(/* throwIfDuplicateKeys= */ true, entries);
+  }
+
+  RegularImmutableMap(boolean throwIfDuplicateKeys, Entry<? extends K, ? extends V>[] entries) {
+    super(throwIfDuplicateKeys, entries);
   }
 }
diff --git a/guava-gwt/src-super/com/google/common/util/concurrent/super/com/google/common/util/concurrent/AbstractFuture.java b/guava-gwt/src-super/com/google/common/util/concurrent/super/com/google/common/util/concurrent/AbstractFuture.java
index 900d5f7d6e73..1ecce78ec43f 100644
--- a/guava-gwt/src-super/com/google/common/util/concurrent/super/com/google/common/util/concurrent/AbstractFuture.java
+++ b/guava-gwt/src-super/com/google/common/util/concurrent/super/com/google/common/util/concurrent/AbstractFuture.java
@@ -36,9 +36,12 @@
 import org.checkerframework.checker.nullness.qual.Nullable;
 
 /** Emulation for AbstractFuture in GWT. */
+@SuppressWarnings("nullness") // TODO(b/147136275): Remove once our checker understands & and |.
 public abstract class AbstractFuture<V> extends InternalFutureFailureAccess
     implements ListenableFuture<V> {
 
+  static final boolean GENERATE_CANCELLATION_CAUSES = false;
+
   /**
    * Tag interface marking trusted subclasses. This enables some optimizations. The implementation
    * of this interface must also be an AbstractFuture and must not override or expose for overriding
diff --git a/guava-gwt/src-super/com/google/common/util/concurrent/super/com/google/common/util/concurrent/GwtFuturesCatchingSpecialization.java b/guava-gwt/src-super/com/google/common/util/concurrent/super/com/google/common/util/concurrent/GwtFuturesCatchingSpecialization.java
index 35cf502a554f..4ce990d322d3 100644
--- a/guava-gwt/src-super/com/google/common/util/concurrent/super/com/google/common/util/concurrent/GwtFuturesCatchingSpecialization.java
+++ b/guava-gwt/src-super/com/google/common/util/concurrent/super/com/google/common/util/concurrent/GwtFuturesCatchingSpecialization.java
@@ -14,8 +14,6 @@
 
 package com.google.common.util.concurrent;
 
-import static com.google.common.util.concurrent.MoreExecutors.directExecutor;
-
 import com.google.common.base.Function;
 import java.util.concurrent.Executor;
 
@@ -31,15 +29,6 @@ abstract class GwtFuturesCatchingSpecialization {
    * your own instanceof tests.
    */
 
-  /** @deprecated Use the overload that requires an executor. */
-  @Deprecated
-  public static <V> ListenableFuture<V> catching(
-      ListenableFuture<? extends V> input,
-      Class<Throwable> exceptionType,
-      Function<? super Throwable, ? extends V> fallback) {
-    return AbstractCatchingFuture.create(input, exceptionType, fallback, directExecutor());
-  }
-
   public static <V> ListenableFuture<V> catching(
       ListenableFuture<? extends V> input,
       Class<Throwable> exceptionType,
@@ -48,15 +37,6 @@ public static <V> ListenableFuture<V> catching(
     return AbstractCatchingFuture.create(input, exceptionType, fallback, executor);
   }
 
-  /** @deprecated Use the overload that requires an executor. */
-  @Deprecated
-  public static <V> ListenableFuture<V> catchingAsync(
-      ListenableFuture<? extends V> input,
-      Class<Throwable> exceptionType,
-      AsyncFunction<? super Throwable, ? extends V> fallback) {
-    return AbstractCatchingFuture.create(input, exceptionType, fallback, directExecutor());
-  }
-
   public static <V> ListenableFuture<V> catchingAsync(
       ListenableFuture<? extends V> input,
       Class<Throwable> exceptionType,
diff --git a/guava-gwt/src-super/com/google/common/util/concurrent/super/com/google/common/util/concurrent/InterruptibleTask.java b/guava-gwt/src-super/com/google/common/util/concurrent/super/com/google/common/util/concurrent/InterruptibleTask.java
index de2f0623695e..1cd9f3e73dd4 100644
--- a/guava-gwt/src-super/com/google/common/util/concurrent/super/com/google/common/util/concurrent/InterruptibleTask.java
+++ b/guava-gwt/src-super/com/google/common/util/concurrent/super/com/google/common/util/concurrent/InterruptibleTask.java
@@ -16,12 +16,14 @@
 
 package com.google.common.util.concurrent;
 
+import static com.google.common.util.concurrent.NullnessCasts.uncheckedCastNullableTToT;
+
 /** Emulation for InterruptibleTask in GWT. */
-abstract class InterruptibleTask<V> implements Runnable {
+abstract class InterruptibleTask<T> implements Runnable {
 
   @Override
   public void run() {
-    V result = null;
+    T result = null;
     Throwable error = null;
     if (isDone()) {
       return;
@@ -31,14 +33,21 @@ public void run() {
     } catch (Throwable t) {
       error = t;
     }
-    afterRanInterruptibly(result, error);
+    if (error == null) {
+      // The cast is safe because of the `run` and `error` checks.
+      afterRanInterruptiblySuccess(uncheckedCastNullableTToT(result));
+    } else {
+      afterRanInterruptiblyFailure(error);
+    }
   }
 
   abstract boolean isDone();
 
-  abstract V runInterruptibly() throws Exception;
+  abstract T runInterruptibly() throws Exception;
+
+  abstract void afterRanInterruptiblySuccess(T result);
 
-  abstract void afterRanInterruptibly(V result, Throwable error);
+  abstract void afterRanInterruptiblyFailure(Throwable error);
 
   final void interruptTask() {}
 
diff --git a/guava-gwt/src/com/google/common/annotations/Annotations.gwt.xml b/guava-gwt/src/com/google/common/annotations/Annotations.gwt.xml
index e86a1bff77f0..529baf56601c 100644
--- a/guava-gwt/src/com/google/common/annotations/Annotations.gwt.xml
+++ b/guava-gwt/src/com/google/common/annotations/Annotations.gwt.xml
@@ -5,24 +5,29 @@
 </source>
 
 <!--
-     We used to set this only for packages that had manual supersource.
-     That worked everywhere that I know of except for one place:
-     when running the GWT util.concurrent tests under Guava.
-     The problem is that GWT responds poorly to two .gwt.xml files in the same Java package:
-     https://goo.gl/pRV3Yn
-     The summary is that it ignores one file in favor of the other.
-     util.concurrent, like nearly all our packages, has two .gwt.xml files: one for prod and one for tests.
-     util.concurrent, unlike our other packages, has, as of this writing, test supersource but no prod supersource.
-     GWT happens to use the prod .gwt.xml, so it looks for no supersource for tests, either.
-     This causes it to fail to find AtomicLongMapTest.
-     Our workaround is to tell GWT that util.concurrent and all other packages have prod supersource, even if they have none.
-     GWT is happy to ignore us when we specify a nonexistent path.
-     (I hope that this workaround does not cause its own problems in the future.)
--->
-<super-source path="super"/>
-<inherits name="com.google.gwt.user.User" />
+    We used to set this only for packages that had manual supersource. That
+    worked everywhere that I know of except for one place: when running the GWT
+    util.concurrent tests under Guava.
+
+    The problem is that GWT responds poorly to two .gwt.xml files in the same
+    Java package; see https://goo.gl/pRV3Yn for details.
+
+    The summary is that it ignores one file in favor of the other.
+    util.concurrent, like nearly all our packages, has two .gwt.xml files: one
+    for prod and one for tests. However, unlike our other packages, as of this
+    writing it has test supersource but no prod supersource.
 
+    GWT happens to use the prod .gwt.xml, so it looks for no supersource for
+    tests, either. This causes it to fail to find AtomicLongMapTest.
 
+    Our workaround is to tell GWT that util.concurrent and all other packages
+    have prod supersource, even if they have none. GWT is happy to ignore us
+    when we specify a nonexistent path.
+
+    (I hope that this workaround does not cause its own problems in the future.)
+-->
+<super-source path="super"/>
 
 <inherits name="com.google.gwt.core.Core" />
+<inherits name="com.google.gwt.user.User" />
 </module>
diff --git a/guava-gwt/src/com/google/common/base/Base.gwt.xml b/guava-gwt/src/com/google/common/base/Base.gwt.xml
index a9a4b1b4ca90..22ca5270a38b 100644
--- a/guava-gwt/src/com/google/common/base/Base.gwt.xml
+++ b/guava-gwt/src/com/google/common/base/Base.gwt.xml
@@ -5,27 +5,30 @@
 </source>
 
 <!--
-     We used to set this only for packages that had manual supersource.
-     That worked everywhere that I know of except for one place:
-     when running the GWT util.concurrent tests under Guava.
-     The problem is that GWT responds poorly to two .gwt.xml files in the same Java package:
-     https://goo.gl/pRV3Yn
-     The summary is that it ignores one file in favor of the other.
-     util.concurrent, like nearly all our packages, has two .gwt.xml files: one for prod and one for tests.
-     util.concurrent, unlike our other packages, has, as of this writing, test supersource but no prod supersource.
-     GWT happens to use the prod .gwt.xml, so it looks for no supersource for tests, either.
-     This causes it to fail to find AtomicLongMapTest.
-     Our workaround is to tell GWT that util.concurrent and all other packages have prod supersource, even if they have none.
-     GWT is happy to ignore us when we specify a nonexistent path.
-     (I hope that this workaround does not cause its own problems in the future.)
--->
-<super-source path="super"/>
-<inherits name="com.google.gwt.user.User" />
+    We used to set this only for packages that had manual supersource. That
+    worked everywhere that I know of except for one place: when running the GWT
+    util.concurrent tests under Guava.
 
-<inherits name="com.google.gwt.user.User" />
-<inherits name="com.google.common.annotations.Annotations" />
+    The problem is that GWT responds poorly to two .gwt.xml files in the same
+    Java package; see https://goo.gl/pRV3Yn for details.
+
+    The summary is that it ignores one file in favor of the other.
+    util.concurrent, like nearly all our packages, has two .gwt.xml files: one
+    for prod and one for tests. However, unlike our other packages, as of this
+    writing it has test supersource but no prod supersource.
 
+    GWT happens to use the prod .gwt.xml, so it looks for no supersource for
+    tests, either. This causes it to fail to find AtomicLongMapTest.
 
+    Our workaround is to tell GWT that util.concurrent and all other packages
+    have prod supersource, even if they have none. GWT is happy to ignore us
+    when we specify a nonexistent path.
 
+    (I hope that this workaround does not cause its own problems in the future.)
+-->
+<super-source path="super"/>
+
+<inherits name="com.google.common.annotations.Annotations" />
 <inherits name="com.google.gwt.core.Core" />
+<inherits name="com.google.gwt.user.User" />
 </module>
diff --git a/guava-gwt/src/com/google/common/cache/Cache.gwt.xml b/guava-gwt/src/com/google/common/cache/Cache.gwt.xml
index 7606251b2b00..0f46529d3dc4 100644
--- a/guava-gwt/src/com/google/common/cache/Cache.gwt.xml
+++ b/guava-gwt/src/com/google/common/cache/Cache.gwt.xml
@@ -5,30 +5,34 @@
 </source>
 
 <!--
-     We used to set this only for packages that had manual supersource.
-     That worked everywhere that I know of except for one place:
-     when running the GWT util.concurrent tests under Guava.
-     The problem is that GWT responds poorly to two .gwt.xml files in the same Java package:
-     https://goo.gl/pRV3Yn
-     The summary is that it ignores one file in favor of the other.
-     util.concurrent, like nearly all our packages, has two .gwt.xml files: one for prod and one for tests.
-     util.concurrent, unlike our other packages, has, as of this writing, test supersource but no prod supersource.
-     GWT happens to use the prod .gwt.xml, so it looks for no supersource for tests, either.
-     This causes it to fail to find AtomicLongMapTest.
-     Our workaround is to tell GWT that util.concurrent and all other packages have prod supersource, even if they have none.
-     GWT is happy to ignore us when we specify a nonexistent path.
-     (I hope that this workaround does not cause its own problems in the future.)
+    We used to set this only for packages that had manual supersource. That
+    worked everywhere that I know of except for one place: when running the GWT
+    util.concurrent tests under Guava.
+
+    The problem is that GWT responds poorly to two .gwt.xml files in the same
+    Java package; see https://goo.gl/pRV3Yn for details.
+
+    The summary is that it ignores one file in favor of the other.
+    util.concurrent, like nearly all our packages, has two .gwt.xml files: one
+    for prod and one for tests. However, unlike our other packages, as of this
+    writing it has test supersource but no prod supersource.
+
+    GWT happens to use the prod .gwt.xml, so it looks for no supersource for
+    tests, either. This causes it to fail to find AtomicLongMapTest.
+
+    Our workaround is to tell GWT that util.concurrent and all other packages
+    have prod supersource, even if they have none. GWT is happy to ignore us
+    when we specify a nonexistent path.
+
+    (I hope that this workaround does not cause its own problems in the future.)
 -->
 <super-source path="super"/>
-<inherits name="com.google.gwt.user.User" />
 
 <inherits name="com.google.common.annotations.Annotations" />
 <inherits name="com.google.common.base.Base" />
 <inherits name="com.google.common.collect.Collect" />
 <inherits name="com.google.common.math.Math" />
 <inherits name="com.google.common.util.concurrent.Concurrent" />
-
-
 <inherits name="com.google.gwt.core.Core" />
-
+<inherits name="com.google.gwt.user.User" />
 </module>
diff --git a/guava-gwt/src/com/google/common/collect/Collect.gwt.xml b/guava-gwt/src/com/google/common/collect/Collect.gwt.xml
index 0d485a374b40..91756f9e8b52 100644
--- a/guava-gwt/src/com/google/common/collect/Collect.gwt.xml
+++ b/guava-gwt/src/com/google/common/collect/Collect.gwt.xml
@@ -5,30 +5,33 @@
 </source>
 
 <!--
-     We used to set this only for packages that had manual supersource.
-     That worked everywhere that I know of except for one place:
-     when running the GWT util.concurrent tests under Guava.
-     The problem is that GWT responds poorly to two .gwt.xml files in the same Java package:
-     https://goo.gl/pRV3Yn
-     The summary is that it ignores one file in favor of the other.
-     util.concurrent, like nearly all our packages, has two .gwt.xml files: one for prod and one for tests.
-     util.concurrent, unlike our other packages, has, as of this writing, test supersource but no prod supersource.
-     GWT happens to use the prod .gwt.xml, so it looks for no supersource for tests, either.
-     This causes it to fail to find AtomicLongMapTest.
-     Our workaround is to tell GWT that util.concurrent and all other packages have prod supersource, even if they have none.
-     GWT is happy to ignore us when we specify a nonexistent path.
-     (I hope that this workaround does not cause its own problems in the future.)
+    We used to set this only for packages that had manual supersource. That
+    worked everywhere that I know of except for one place: when running the GWT
+    util.concurrent tests under Guava.
+
+    The problem is that GWT responds poorly to two .gwt.xml files in the same
+    Java package; see https://goo.gl/pRV3Yn for details.
+
+    The summary is that it ignores one file in favor of the other.
+    util.concurrent, like nearly all our packages, has two .gwt.xml files: one
+    for prod and one for tests. However, unlike our other packages, as of this
+    writing it has test supersource but no prod supersource.
+
+    GWT happens to use the prod .gwt.xml, so it looks for no supersource for
+    tests, either. This causes it to fail to find AtomicLongMapTest.
+
+    Our workaround is to tell GWT that util.concurrent and all other packages
+    have prod supersource, even if they have none. GWT is happy to ignore us
+    when we specify a nonexistent path.
+
+    (I hope that this workaround does not cause its own problems in the future.)
 -->
 <super-source path="super"/>
-<inherits name="com.google.gwt.user.User" />
 
-<inherits name="com.google.gwt.user.User" />
 <inherits name="com.google.common.annotations.Annotations" />
 <inherits name="com.google.common.base.Base" />
 <inherits name="com.google.common.math.Math" />
 <inherits name="com.google.common.primitives.Primitives" />
-
-
-
 <inherits name="com.google.gwt.core.Core" />
+<inherits name="com.google.gwt.user.User" />
 </module>
diff --git a/guava-gwt/src/com/google/common/escape/Escape.gwt.xml b/guava-gwt/src/com/google/common/escape/Escape.gwt.xml
index e22e2c792116..a3ddbba449b9 100644
--- a/guava-gwt/src/com/google/common/escape/Escape.gwt.xml
+++ b/guava-gwt/src/com/google/common/escape/Escape.gwt.xml
@@ -5,27 +5,31 @@
 </source>
 
 <!--
-     We used to set this only for packages that had manual supersource.
-     That worked everywhere that I know of except for one place:
-     when running the GWT util.concurrent tests under Guava.
-     The problem is that GWT responds poorly to two .gwt.xml files in the same Java package:
-     https://goo.gl/pRV3Yn
-     The summary is that it ignores one file in favor of the other.
-     util.concurrent, like nearly all our packages, has two .gwt.xml files: one for prod and one for tests.
-     util.concurrent, unlike our other packages, has, as of this writing, test supersource but no prod supersource.
-     GWT happens to use the prod .gwt.xml, so it looks for no supersource for tests, either.
-     This causes it to fail to find AtomicLongMapTest.
-     Our workaround is to tell GWT that util.concurrent and all other packages have prod supersource, even if they have none.
-     GWT is happy to ignore us when we specify a nonexistent path.
-     (I hope that this workaround does not cause its own problems in the future.)
+    We used to set this only for packages that had manual supersource. That
+    worked everywhere that I know of except for one place: when running the GWT
+    util.concurrent tests under Guava.
+
+    The problem is that GWT responds poorly to two .gwt.xml files in the same
+    Java package; see https://goo.gl/pRV3Yn for details.
+
+    The summary is that it ignores one file in favor of the other.
+    util.concurrent, like nearly all our packages, has two .gwt.xml files: one
+    for prod and one for tests. However, unlike our other packages, as of this
+    writing it has test supersource but no prod supersource.
+
+    GWT happens to use the prod .gwt.xml, so it looks for no supersource for
+    tests, either. This causes it to fail to find AtomicLongMapTest.
+
+    Our workaround is to tell GWT that util.concurrent and all other packages
+    have prod supersource, even if they have none. GWT is happy to ignore us
+    when we specify a nonexistent path.
+
+    (I hope that this workaround does not cause its own problems in the future.)
 -->
 <super-source path="super"/>
-<inherits name="com.google.gwt.user.User" />
 
 <inherits name="com.google.common.annotations.Annotations" />
 <inherits name="com.google.common.base.Base" />
-
-
 <inherits name="com.google.gwt.core.Core" />
-
+<inherits name="com.google.gwt.user.User" />
 </module>
diff --git a/guava-gwt/src/com/google/common/html/Html.gwt.xml b/guava-gwt/src/com/google/common/html/Html.gwt.xml
index 8c7d9ff9a821..de5e7ad51d90 100644
--- a/guava-gwt/src/com/google/common/html/Html.gwt.xml
+++ b/guava-gwt/src/com/google/common/html/Html.gwt.xml
@@ -5,25 +5,31 @@
 </source>
 
 <!--
-     We used to set this only for packages that had manual supersource.
-     That worked everywhere that I know of except for one place:
-     when running the GWT util.concurrent tests under Guava.
-     The problem is that GWT responds poorly to two .gwt.xml files in the same Java package:
-     https://goo.gl/pRV3Yn
-     The summary is that it ignores one file in favor of the other.
-     util.concurrent, like nearly all our packages, has two .gwt.xml files: one for prod and one for tests.
-     util.concurrent, unlike our other packages, has, as of this writing, test supersource but no prod supersource.
-     GWT happens to use the prod .gwt.xml, so it looks for no supersource for tests, either.
-     This causes it to fail to find AtomicLongMapTest.
-     Our workaround is to tell GWT that util.concurrent and all other packages have prod supersource, even if they have none.
-     GWT is happy to ignore us when we specify a nonexistent path.
-     (I hope that this workaround does not cause its own problems in the future.)
+    We used to set this only for packages that had manual supersource. That
+    worked everywhere that I know of except for one place: when running the GWT
+    util.concurrent tests under Guava.
+
+    The problem is that GWT responds poorly to two .gwt.xml files in the same
+    Java package; see https://goo.gl/pRV3Yn for details.
+
+    The summary is that it ignores one file in favor of the other.
+    util.concurrent, like nearly all our packages, has two .gwt.xml files: one
+    for prod and one for tests. However, unlike our other packages, as of this
+    writing it has test supersource but no prod supersource.
+
+    GWT happens to use the prod .gwt.xml, so it looks for no supersource for
+    tests, either. This causes it to fail to find AtomicLongMapTest.
+
+    Our workaround is to tell GWT that util.concurrent and all other packages
+    have prod supersource, even if they have none. GWT is happy to ignore us
+    when we specify a nonexistent path.
+
+    (I hope that this workaround does not cause its own problems in the future.)
 -->
 <super-source path="super"/>
-<inherits name="com.google.gwt.user.User" />
-
 
 <inherits name="com.google.common.annotations.Annotations" />
 <inherits name="com.google.common.escape.Escape" />
 <inherits name="com.google.gwt.core.Core" />
+<inherits name="com.google.gwt.user.User" />
 </module>
diff --git a/guava-gwt/src/com/google/common/io/Io.gwt.xml b/guava-gwt/src/com/google/common/io/Io.gwt.xml
index 8a61fb71b0b8..91756f9e8b52 100644
--- a/guava-gwt/src/com/google/common/io/Io.gwt.xml
+++ b/guava-gwt/src/com/google/common/io/Io.gwt.xml
@@ -5,29 +5,33 @@
 </source>
 
 <!--
-     We used to set this only for packages that had manual supersource.
-     That worked everywhere that I know of except for one place:
-     when running the GWT util.concurrent tests under Guava.
-     The problem is that GWT responds poorly to two .gwt.xml files in the same Java package:
-     https://goo.gl/pRV3Yn
-     The summary is that it ignores one file in favor of the other.
-     util.concurrent, like nearly all our packages, has two .gwt.xml files: one for prod and one for tests.
-     util.concurrent, unlike our other packages, has, as of this writing, test supersource but no prod supersource.
-     GWT happens to use the prod .gwt.xml, so it looks for no supersource for tests, either.
-     This causes it to fail to find AtomicLongMapTest.
-     Our workaround is to tell GWT that util.concurrent and all other packages have prod supersource, even if they have none.
-     GWT is happy to ignore us when we specify a nonexistent path.
-     (I hope that this workaround does not cause its own problems in the future.)
+    We used to set this only for packages that had manual supersource. That
+    worked everywhere that I know of except for one place: when running the GWT
+    util.concurrent tests under Guava.
+
+    The problem is that GWT responds poorly to two .gwt.xml files in the same
+    Java package; see https://goo.gl/pRV3Yn for details.
+
+    The summary is that it ignores one file in favor of the other.
+    util.concurrent, like nearly all our packages, has two .gwt.xml files: one
+    for prod and one for tests. However, unlike our other packages, as of this
+    writing it has test supersource but no prod supersource.
+
+    GWT happens to use the prod .gwt.xml, so it looks for no supersource for
+    tests, either. This causes it to fail to find AtomicLongMapTest.
+
+    Our workaround is to tell GWT that util.concurrent and all other packages
+    have prod supersource, even if they have none. GWT is happy to ignore us
+    when we specify a nonexistent path.
+
+    (I hope that this workaround does not cause its own problems in the future.)
 -->
 <super-source path="super"/>
-<inherits name="com.google.gwt.user.User" />
 
 <inherits name="com.google.common.annotations.Annotations" />
 <inherits name="com.google.common.base.Base" />
 <inherits name="com.google.common.math.Math" />
 <inherits name="com.google.common.primitives.Primitives" />
-
-
 <inherits name="com.google.gwt.core.Core" />
-
+<inherits name="com.google.gwt.user.User" />
 </module>
diff --git a/guava-gwt/src/com/google/common/math/Math.gwt.xml b/guava-gwt/src/com/google/common/math/Math.gwt.xml
index 5f2b44954c51..6afbe44c1411 100644
--- a/guava-gwt/src/com/google/common/math/Math.gwt.xml
+++ b/guava-gwt/src/com/google/common/math/Math.gwt.xml
@@ -5,28 +5,32 @@
 </source>
 
 <!--
-     We used to set this only for packages that had manual supersource.
-     That worked everywhere that I know of except for one place:
-     when running the GWT util.concurrent tests under Guava.
-     The problem is that GWT responds poorly to two .gwt.xml files in the same Java package:
-     https://goo.gl/pRV3Yn
-     The summary is that it ignores one file in favor of the other.
-     util.concurrent, like nearly all our packages, has two .gwt.xml files: one for prod and one for tests.
-     util.concurrent, unlike our other packages, has, as of this writing, test supersource but no prod supersource.
-     GWT happens to use the prod .gwt.xml, so it looks for no supersource for tests, either.
-     This causes it to fail to find AtomicLongMapTest.
-     Our workaround is to tell GWT that util.concurrent and all other packages have prod supersource, even if they have none.
-     GWT is happy to ignore us when we specify a nonexistent path.
-     (I hope that this workaround does not cause its own problems in the future.)
+    We used to set this only for packages that had manual supersource. That
+    worked everywhere that I know of except for one place: when running the GWT
+    util.concurrent tests under Guava.
+
+    The problem is that GWT responds poorly to two .gwt.xml files in the same
+    Java package; see https://goo.gl/pRV3Yn for details.
+
+    The summary is that it ignores one file in favor of the other.
+    util.concurrent, like nearly all our packages, has two .gwt.xml files: one
+    for prod and one for tests. However, unlike our other packages, as of this
+    writing it has test supersource but no prod supersource.
+
+    GWT happens to use the prod .gwt.xml, so it looks for no supersource for
+    tests, either. This causes it to fail to find AtomicLongMapTest.
+
+    Our workaround is to tell GWT that util.concurrent and all other packages
+    have prod supersource, even if they have none. GWT is happy to ignore us
+    when we specify a nonexistent path.
+
+    (I hope that this workaround does not cause its own problems in the future.)
 -->
 <super-source path="super"/>
-<inherits name="com.google.gwt.user.User" />
 
 <inherits name="com.google.common.annotations.Annotations" />
 <inherits name="com.google.common.base.Base" />
 <inherits name="com.google.common.primitives.Primitives" />
-
-
 <inherits name="com.google.gwt.core.Core" />
-
+<inherits name="com.google.gwt.user.User" />
 </module>
diff --git a/guava-gwt/src/com/google/common/net/Net.gwt.xml b/guava-gwt/src/com/google/common/net/Net.gwt.xml
index 339637a10412..039f77c1f5e4 100644
--- a/guava-gwt/src/com/google/common/net/Net.gwt.xml
+++ b/guava-gwt/src/com/google/common/net/Net.gwt.xml
@@ -5,32 +5,35 @@
 </source>
 
 <!--
-     We used to set this only for packages that had manual supersource.
-     That worked everywhere that I know of except for one place:
-     when running the GWT util.concurrent tests under Guava.
-     The problem is that GWT responds poorly to two .gwt.xml files in the same Java package:
-     https://goo.gl/pRV3Yn
-     The summary is that it ignores one file in favor of the other.
-     util.concurrent, like nearly all our packages, has two .gwt.xml files: one for prod and one for tests.
-     util.concurrent, unlike our other packages, has, as of this writing, test supersource but no prod supersource.
-     GWT happens to use the prod .gwt.xml, so it looks for no supersource for tests, either.
-     This causes it to fail to find AtomicLongMapTest.
-     Our workaround is to tell GWT that util.concurrent and all other packages have prod supersource, even if they have none.
-     GWT is happy to ignore us when we specify a nonexistent path.
-     (I hope that this workaround does not cause its own problems in the future.)
+    We used to set this only for packages that had manual supersource. That
+    worked everywhere that I know of except for one place: when running the GWT
+    util.concurrent tests under Guava.
+
+    The problem is that GWT responds poorly to two .gwt.xml files in the same
+    Java package; see https://goo.gl/pRV3Yn for details.
+
+    The summary is that it ignores one file in favor of the other.
+    util.concurrent, like nearly all our packages, has two .gwt.xml files: one
+    for prod and one for tests. However, unlike our other packages, as of this
+    writing it has test supersource but no prod supersource.
+
+    GWT happens to use the prod .gwt.xml, so it looks for no supersource for
+    tests, either. This causes it to fail to find AtomicLongMapTest.
+
+    Our workaround is to tell GWT that util.concurrent and all other packages
+    have prod supersource, even if they have none. GWT is happy to ignore us
+    when we specify a nonexistent path.
+
+    (I hope that this workaround does not cause its own problems in the future.)
 -->
 <super-source path="super"/>
-<inherits name="com.google.gwt.user.User" />
 
-<inherits name="com.google.gwt.user.User" />
 <inherits name="com.google.common.annotations.Annotations" />
 <inherits name="com.google.common.base.Base" />
 <inherits name="com.google.common.collect.Collect" />
 <inherits name="com.google.common.escape.Escape" />
+<inherits name="com.google.gwt.core.Core" />
+<inherits name="com.google.gwt.user.User" />
 <inherits name="com.google.thirdparty.publicsuffix.PublicSuffixPatterns" />
 <inherits name="com.google.thirdparty.publicsuffix.PublicSuffixType" />
-
-
-<inherits name="com.google.gwt.core.Core" />
-
 </module>
diff --git a/guava-gwt/src/com/google/common/primitives/Primitives.gwt.xml b/guava-gwt/src/com/google/common/primitives/Primitives.gwt.xml
index e076f8765877..a3ddbba449b9 100644
--- a/guava-gwt/src/com/google/common/primitives/Primitives.gwt.xml
+++ b/guava-gwt/src/com/google/common/primitives/Primitives.gwt.xml
@@ -5,28 +5,31 @@
 </source>
 
 <!--
-     We used to set this only for packages that had manual supersource.
-     That worked everywhere that I know of except for one place:
-     when running the GWT util.concurrent tests under Guava.
-     The problem is that GWT responds poorly to two .gwt.xml files in the same Java package:
-     https://goo.gl/pRV3Yn
-     The summary is that it ignores one file in favor of the other.
-     util.concurrent, like nearly all our packages, has two .gwt.xml files: one for prod and one for tests.
-     util.concurrent, unlike our other packages, has, as of this writing, test supersource but no prod supersource.
-     GWT happens to use the prod .gwt.xml, so it looks for no supersource for tests, either.
-     This causes it to fail to find AtomicLongMapTest.
-     Our workaround is to tell GWT that util.concurrent and all other packages have prod supersource, even if they have none.
-     GWT is happy to ignore us when we specify a nonexistent path.
-     (I hope that this workaround does not cause its own problems in the future.)
+    We used to set this only for packages that had manual supersource. That
+    worked everywhere that I know of except for one place: when running the GWT
+    util.concurrent tests under Guava.
+
+    The problem is that GWT responds poorly to two .gwt.xml files in the same
+    Java package; see https://goo.gl/pRV3Yn for details.
+
+    The summary is that it ignores one file in favor of the other.
+    util.concurrent, like nearly all our packages, has two .gwt.xml files: one
+    for prod and one for tests. However, unlike our other packages, as of this
+    writing it has test supersource but no prod supersource.
+
+    GWT happens to use the prod .gwt.xml, so it looks for no supersource for
+    tests, either. This causes it to fail to find AtomicLongMapTest.
+
+    Our workaround is to tell GWT that util.concurrent and all other packages
+    have prod supersource, even if they have none. GWT is happy to ignore us
+    when we specify a nonexistent path.
+
+    (I hope that this workaround does not cause its own problems in the future.)
 -->
 <super-source path="super"/>
-<inherits name="com.google.gwt.user.User" />
 
-<inherits name="com.google.gwt.user.User" />
 <inherits name="com.google.common.annotations.Annotations" />
 <inherits name="com.google.common.base.Base" />
-
-
-
 <inherits name="com.google.gwt.core.Core" />
+<inherits name="com.google.gwt.user.User" />
 </module>
diff --git a/guava-gwt/src/com/google/common/util/concurrent/Concurrent.gwt.xml b/guava-gwt/src/com/google/common/util/concurrent/Concurrent.gwt.xml
index f47c827c9d40..2fdeb6b88daf 100644
--- a/guava-gwt/src/com/google/common/util/concurrent/Concurrent.gwt.xml
+++ b/guava-gwt/src/com/google/common/util/concurrent/Concurrent.gwt.xml
@@ -5,29 +5,33 @@
 </source>
 
 <!--
-     We used to set this only for packages that had manual supersource.
-     That worked everywhere that I know of except for one place:
-     when running the GWT util.concurrent tests under Guava.
-     The problem is that GWT responds poorly to two .gwt.xml files in the same Java package:
-     https://goo.gl/pRV3Yn
-     The summary is that it ignores one file in favor of the other.
-     util.concurrent, like nearly all our packages, has two .gwt.xml files: one for prod and one for tests.
-     util.concurrent, unlike our other packages, has, as of this writing, test supersource but no prod supersource.
-     GWT happens to use the prod .gwt.xml, so it looks for no supersource for tests, either.
-     This causes it to fail to find AtomicLongMapTest.
-     Our workaround is to tell GWT that util.concurrent and all other packages have prod supersource, even if they have none.
-     GWT is happy to ignore us when we specify a nonexistent path.
-     (I hope that this workaround does not cause its own problems in the future.)
+    We used to set this only for packages that had manual supersource. That
+    worked everywhere that I know of except for one place: when running the GWT
+    util.concurrent tests under Guava.
+
+    The problem is that GWT responds poorly to two .gwt.xml files in the same
+    Java package; see https://goo.gl/pRV3Yn for details.
+
+    The summary is that it ignores one file in favor of the other.
+    util.concurrent, like nearly all our packages, has two .gwt.xml files: one
+    for prod and one for tests. However, unlike our other packages, as of this
+    writing it has test supersource but no prod supersource.
+
+    GWT happens to use the prod .gwt.xml, so it looks for no supersource for
+    tests, either. This causes it to fail to find AtomicLongMapTest.
+
+    Our workaround is to tell GWT that util.concurrent and all other packages
+    have prod supersource, even if they have none. GWT is happy to ignore us
+    when we specify a nonexistent path.
+
+    (I hope that this workaround does not cause its own problems in the future.)
 -->
 <super-source path="super"/>
-<inherits name="com.google.gwt.user.User" />
 
 <inherits name="com.google.common.annotations.Annotations" />
 <inherits name="com.google.common.base.Base" />
 <inherits name="com.google.common.collect.Collect" />
-<inherits name="elemental2.promise.Promise" />
-
-
-
 <inherits name="com.google.gwt.core.Core" />
+<inherits name="com.google.gwt.user.User" />
+<inherits name="elemental2.promise.Promise" />
 </module>
diff --git a/guava-gwt/src/com/google/common/xml/Xml.gwt.xml b/guava-gwt/src/com/google/common/xml/Xml.gwt.xml
index d3409505cfc9..eec7e7bba19c 100644
--- a/guava-gwt/src/com/google/common/xml/Xml.gwt.xml
+++ b/guava-gwt/src/com/google/common/xml/Xml.gwt.xml
@@ -5,26 +5,32 @@
 </source>
 
 <!--
-     We used to set this only for packages that had manual supersource.
-     That worked everywhere that I know of except for one place:
-     when running the GWT util.concurrent tests under Guava.
-     The problem is that GWT responds poorly to two .gwt.xml files in the same Java package:
-     https://goo.gl/pRV3Yn
-     The summary is that it ignores one file in favor of the other.
-     util.concurrent, like nearly all our packages, has two .gwt.xml files: one for prod and one for tests.
-     util.concurrent, unlike our other packages, has, as of this writing, test supersource but no prod supersource.
-     GWT happens to use the prod .gwt.xml, so it looks for no supersource for tests, either.
-     This causes it to fail to find AtomicLongMapTest.
-     Our workaround is to tell GWT that util.concurrent and all other packages have prod supersource, even if they have none.
-     GWT is happy to ignore us when we specify a nonexistent path.
-     (I hope that this workaround does not cause its own problems in the future.)
+    We used to set this only for packages that had manual supersource. That
+    worked everywhere that I know of except for one place: when running the GWT
+    util.concurrent tests under Guava.
+
+    The problem is that GWT responds poorly to two .gwt.xml files in the same
+    Java package; see https://goo.gl/pRV3Yn for details.
+
+    The summary is that it ignores one file in favor of the other.
+    util.concurrent, like nearly all our packages, has two .gwt.xml files: one
+    for prod and one for tests. However, unlike our other packages, as of this
+    writing it has test supersource but no prod supersource.
+
+    GWT happens to use the prod .gwt.xml, so it looks for no supersource for
+    tests, either. This causes it to fail to find AtomicLongMapTest.
+
+    Our workaround is to tell GWT that util.concurrent and all other packages
+    have prod supersource, even if they have none. GWT is happy to ignore us
+    when we specify a nonexistent path.
+
+    (I hope that this workaround does not cause its own problems in the future.)
 -->
 <super-source path="super"/>
-<inherits name="com.google.gwt.user.User" />
 
 <inherits name="com.google.common.annotations.Annotations" />
 <inherits name="com.google.common.base.Base" />
 <inherits name="com.google.common.escape.Escape" />
-
 <inherits name="com.google.gwt.core.Core" />
+<inherits name="com.google.gwt.user.User" />
 </module>
diff --git a/guava-gwt/src/com/google/thirdparty/publicsuffix/PublicSuffixPatterns.gwt.xml b/guava-gwt/src/com/google/thirdparty/publicsuffix/PublicSuffixPatterns.gwt.xml
index d5dd2908c856..f35ad8c4814f 100644
--- a/guava-gwt/src/com/google/thirdparty/publicsuffix/PublicSuffixPatterns.gwt.xml
+++ b/guava-gwt/src/com/google/thirdparty/publicsuffix/PublicSuffixPatterns.gwt.xml
@@ -5,26 +5,33 @@
 </source>
 
 <!--
-     We used to set this only for packages that had manual supersource.
-     That worked everywhere that I know of except for one place:
-     when running the GWT util.concurrent tests under Guava.
-     The problem is that GWT responds poorly to two .gwt.xml files in the same Java package:
-     https://goo.gl/pRV3Yn
-     The summary is that it ignores one file in favor of the other.
-     util.concurrent, like nearly all our packages, has two .gwt.xml files: one for prod and one for tests.
-     util.concurrent, unlike our other packages, has, as of this writing, test supersource but no prod supersource.
-     GWT happens to use the prod .gwt.xml, so it looks for no supersource for tests, either.
-     This causes it to fail to find AtomicLongMapTest.
-     Our workaround is to tell GWT that util.concurrent and all other packages have prod supersource, even if they have none.
-     GWT is happy to ignore us when we specify a nonexistent path.
-     (I hope that this workaround does not cause its own problems in the future.)
+    We used to set this only for packages that had manual supersource. That
+    worked everywhere that I know of except for one place: when running the GWT
+    util.concurrent tests under Guava.
+
+    The problem is that GWT responds poorly to two .gwt.xml files in the same
+    Java package; see https://goo.gl/pRV3Yn for details.
+
+    The summary is that it ignores one file in favor of the other.
+    util.concurrent, like nearly all our packages, has two .gwt.xml files: one
+    for prod and one for tests. However, unlike our other packages, as of this
+    writing it has test supersource but no prod supersource.
+
+    GWT happens to use the prod .gwt.xml, so it looks for no supersource for
+    tests, either. This causes it to fail to find AtomicLongMapTest.
+
+    Our workaround is to tell GWT that util.concurrent and all other packages
+    have prod supersource, even if they have none. GWT is happy to ignore us
+    when we specify a nonexistent path.
+
+    (I hope that this workaround does not cause its own problems in the future.)
 -->
 <super-source path="super"/>
-<inherits name="com.google.gwt.user.User" />
 
-<inherits name="com.google.thirdparty.publicsuffix.PublicSuffixType" />
 <inherits name="com.google.common.annotations.Annotations" />
 <inherits name="com.google.common.base.Base" />
 <inherits name="com.google.common.collect.Collect" />
 <inherits name="com.google.gwt.core.Core" />
+<inherits name="com.google.gwt.user.User" />
+<inherits name="com.google.thirdparty.publicsuffix.PublicSuffixType" />
 </module>
diff --git a/guava-gwt/src/com/google/thirdparty/publicsuffix/PublicSuffixType.gwt.xml b/guava-gwt/src/com/google/thirdparty/publicsuffix/PublicSuffixType.gwt.xml
index ffbcaf104f2e..22ca5270a38b 100644
--- a/guava-gwt/src/com/google/thirdparty/publicsuffix/PublicSuffixType.gwt.xml
+++ b/guava-gwt/src/com/google/thirdparty/publicsuffix/PublicSuffixType.gwt.xml
@@ -5,23 +5,30 @@
 </source>
 
 <!--
-     We used to set this only for packages that had manual supersource.
-     That worked everywhere that I know of except for one place:
-     when running the GWT util.concurrent tests under Guava.
-     The problem is that GWT responds poorly to two .gwt.xml files in the same Java package:
-     https://goo.gl/pRV3Yn
-     The summary is that it ignores one file in favor of the other.
-     util.concurrent, like nearly all our packages, has two .gwt.xml files: one for prod and one for tests.
-     util.concurrent, unlike our other packages, has, as of this writing, test supersource but no prod supersource.
-     GWT happens to use the prod .gwt.xml, so it looks for no supersource for tests, either.
-     This causes it to fail to find AtomicLongMapTest.
-     Our workaround is to tell GWT that util.concurrent and all other packages have prod supersource, even if they have none.
-     GWT is happy to ignore us when we specify a nonexistent path.
-     (I hope that this workaround does not cause its own problems in the future.)
+    We used to set this only for packages that had manual supersource. That
+    worked everywhere that I know of except for one place: when running the GWT
+    util.concurrent tests under Guava.
+
+    The problem is that GWT responds poorly to two .gwt.xml files in the same
+    Java package; see https://goo.gl/pRV3Yn for details.
+
+    The summary is that it ignores one file in favor of the other.
+    util.concurrent, like nearly all our packages, has two .gwt.xml files: one
+    for prod and one for tests. However, unlike our other packages, as of this
+    writing it has test supersource but no prod supersource.
+
+    GWT happens to use the prod .gwt.xml, so it looks for no supersource for
+    tests, either. This causes it to fail to find AtomicLongMapTest.
+
+    Our workaround is to tell GWT that util.concurrent and all other packages
+    have prod supersource, even if they have none. GWT is happy to ignore us
+    when we specify a nonexistent path.
+
+    (I hope that this workaround does not cause its own problems in the future.)
 -->
 <super-source path="super"/>
-<inherits name="com.google.gwt.user.User" />
 
 <inherits name="com.google.common.annotations.Annotations" />
 <inherits name="com.google.gwt.core.Core" />
+<inherits name="com.google.gwt.user.User" />
 </module>
diff --git a/guava-gwt/test/com/google/common/collect/testing/Testing.gwt.xml b/guava-gwt/test/com/google/common/collect/testing/Testing.gwt.xml
index eabb5a51fb94..5d17a81f98a9 100644
--- a/guava-gwt/test/com/google/common/collect/testing/Testing.gwt.xml
+++ b/guava-gwt/test/com/google/common/collect/testing/Testing.gwt.xml
@@ -5,31 +5,35 @@
 </source>
 
 <!--
-     We used to set this only for packages that had manual supersource.
-     That worked everywhere that I know of except for one place:
-     when running the GWT util.concurrent tests under Guava.
-     The problem is that GWT responds poorly to two .gwt.xml files in the same Java package:
-     https://goo.gl/pRV3Yn
-     The summary is that it ignores one file in favor of the other.
-     util.concurrent, like nearly all our packages, has two .gwt.xml files: one for prod and one for tests.
-     util.concurrent, unlike our other packages, has, as of this writing, test supersource but no prod supersource.
-     GWT happens to use the prod .gwt.xml, so it looks for no supersource for tests, either.
-     This causes it to fail to find AtomicLongMapTest.
-     Our workaround is to tell GWT that util.concurrent and all other packages have prod supersource, even if they have none.
-     GWT is happy to ignore us when we specify a nonexistent path.
-     (I hope that this workaround does not cause its own problems in the future.)
+    We used to set this only for packages that had manual supersource. That
+    worked everywhere that I know of except for one place: when running the GWT
+    util.concurrent tests under Guava.
+
+    The problem is that GWT responds poorly to two .gwt.xml files in the same
+    Java package; see https://goo.gl/pRV3Yn for details.
+
+    The summary is that it ignores one file in favor of the other.
+    util.concurrent, like nearly all our packages, has two .gwt.xml files: one
+    for prod and one for tests. However, unlike our other packages, as of this
+    writing it has test supersource but no prod supersource.
+
+    GWT happens to use the prod .gwt.xml, so it looks for no supersource for
+    tests, either. This causes it to fail to find AtomicLongMapTest.
+
+    Our workaround is to tell GWT that util.concurrent and all other packages
+    have prod supersource, even if they have none. GWT is happy to ignore us
+    when we specify a nonexistent path.
+
+    (I hope that this workaround does not cause its own problems in the future.)
 -->
 <super-source path="super"/>
-<inherits name="com.google.gwt.user.User" />
 
-<inherits name="com.google.gwt.junit.JUnit" />
 <inherits name="com.google.common.annotations.Annotations" />
 <inherits name="com.google.common.base.Base" />
 <inherits name="com.google.common.collect.Collect" />
 <inherits name="com.google.common.primitives.Primitives" />
 <inherits name="com.google.common.testing.Testing" />
-
-
 <inherits name="com.google.gwt.core.Core" />
-
+<inherits name="com.google.gwt.junit.JUnit" />
+<inherits name="com.google.gwt.user.User" />
 </module>
diff --git a/guava-gwt/test/com/google/common/collect/testing/google/Google.gwt.xml b/guava-gwt/test/com/google/common/collect/testing/google/Google.gwt.xml
index 66a788469169..54f33bfb0da9 100644
--- a/guava-gwt/test/com/google/common/collect/testing/google/Google.gwt.xml
+++ b/guava-gwt/test/com/google/common/collect/testing/google/Google.gwt.xml
@@ -5,24 +5,29 @@
 </source>
 
 <!--
-     We used to set this only for packages that had manual supersource.
-     That worked everywhere that I know of except for one place:
-     when running the GWT util.concurrent tests under Guava.
-     The problem is that GWT responds poorly to two .gwt.xml files in the same Java package:
-     https://goo.gl/pRV3Yn
-     The summary is that it ignores one file in favor of the other.
-     util.concurrent, like nearly all our packages, has two .gwt.xml files: one for prod and one for tests.
-     util.concurrent, unlike our other packages, has, as of this writing, test supersource but no prod supersource.
-     GWT happens to use the prod .gwt.xml, so it looks for no supersource for tests, either.
-     This causes it to fail to find AtomicLongMapTest.
-     Our workaround is to tell GWT that util.concurrent and all other packages have prod supersource, even if they have none.
-     GWT is happy to ignore us when we specify a nonexistent path.
-     (I hope that this workaround does not cause its own problems in the future.)
+    We used to set this only for packages that had manual supersource. That
+    worked everywhere that I know of except for one place: when running the GWT
+    util.concurrent tests under Guava.
+
+    The problem is that GWT responds poorly to two .gwt.xml files in the same
+    Java package; see https://goo.gl/pRV3Yn for details.
+
+    The summary is that it ignores one file in favor of the other.
+    util.concurrent, like nearly all our packages, has two .gwt.xml files: one
+    for prod and one for tests. However, unlike our other packages, as of this
+    writing it has test supersource but no prod supersource.
+
+    GWT happens to use the prod .gwt.xml, so it looks for no supersource for
+    tests, either. This causes it to fail to find AtomicLongMapTest.
+
+    Our workaround is to tell GWT that util.concurrent and all other packages
+    have prod supersource, even if they have none. GWT is happy to ignore us
+    when we specify a nonexistent path.
+
+    (I hope that this workaround does not cause its own problems in the future.)
 -->
 <super-source path="super"/>
-<inherits name="com.google.gwt.user.User" />
 
-<inherits name="com.google.gwt.junit.JUnit" />
 <inherits name="com.google.common.annotations.Annotations" />
 <inherits name="com.google.common.base.Base" />
 <inherits name="com.google.common.collect.Collect" />
@@ -30,7 +35,6 @@
 <inherits name="com.google.common.primitives.Primitives" />
 <inherits name="com.google.common.testing.Testing" />
 <inherits name="com.google.gwt.core.Core" />
-
-
-
+<inherits name="com.google.gwt.junit.JUnit" />
+<inherits name="com.google.gwt.user.User" />
 </module>
diff --git a/guava-gwt/test/com/google/common/escape/testing/Testing.gwt.xml b/guava-gwt/test/com/google/common/escape/testing/Testing.gwt.xml
index 85cb436b8781..0957af4f33ad 100644
--- a/guava-gwt/test/com/google/common/escape/testing/Testing.gwt.xml
+++ b/guava-gwt/test/com/google/common/escape/testing/Testing.gwt.xml
@@ -5,25 +5,32 @@
 </source>
 
 <!--
-     We used to set this only for packages that had manual supersource.
-     That worked everywhere that I know of except for one place:
-     when running the GWT util.concurrent tests under Guava.
-     The problem is that GWT responds poorly to two .gwt.xml files in the same Java package:
-     https://goo.gl/pRV3Yn
-     The summary is that it ignores one file in favor of the other.
-     util.concurrent, like nearly all our packages, has two .gwt.xml files: one for prod and one for tests.
-     util.concurrent, unlike our other packages, has, as of this writing, test supersource but no prod supersource.
-     GWT happens to use the prod .gwt.xml, so it looks for no supersource for tests, either.
-     This causes it to fail to find AtomicLongMapTest.
-     Our workaround is to tell GWT that util.concurrent and all other packages have prod supersource, even if they have none.
-     GWT is happy to ignore us when we specify a nonexistent path.
-     (I hope that this workaround does not cause its own problems in the future.)
+    We used to set this only for packages that had manual supersource. That
+    worked everywhere that I know of except for one place: when running the GWT
+    util.concurrent tests under Guava.
+
+    The problem is that GWT responds poorly to two .gwt.xml files in the same
+    Java package; see https://goo.gl/pRV3Yn for details.
+
+    The summary is that it ignores one file in favor of the other.
+    util.concurrent, like nearly all our packages, has two .gwt.xml files: one
+    for prod and one for tests. However, unlike our other packages, as of this
+    writing it has test supersource but no prod supersource.
+
+    GWT happens to use the prod .gwt.xml, so it looks for no supersource for
+    tests, either. This causes it to fail to find AtomicLongMapTest.
+
+    Our workaround is to tell GWT that util.concurrent and all other packages
+    have prod supersource, even if they have none. GWT is happy to ignore us
+    when we specify a nonexistent path.
+
+    (I hope that this workaround does not cause its own problems in the future.)
 -->
 <super-source path="super"/>
-<inherits name="com.google.gwt.user.User" />
 
-<inherits name="com.google.gwt.junit.JUnit" />
 <inherits name="com.google.common.annotations.Annotations" />
 <inherits name="com.google.common.escape.Escape" />
 <inherits name="com.google.gwt.core.Core" />
+<inherits name="com.google.gwt.junit.JUnit" />
+<inherits name="com.google.gwt.user.User" />
 </module>
diff --git a/guava-gwt/test/com/google/common/testing/Testing.gwt.xml b/guava-gwt/test/com/google/common/testing/Testing.gwt.xml
index 00652f1a03dc..72c486dbccec 100644
--- a/guava-gwt/test/com/google/common/testing/Testing.gwt.xml
+++ b/guava-gwt/test/com/google/common/testing/Testing.gwt.xml
@@ -5,29 +5,33 @@
 </source>
 
 <!--
-     We used to set this only for packages that had manual supersource.
-     That worked everywhere that I know of except for one place:
-     when running the GWT util.concurrent tests under Guava.
-     The problem is that GWT responds poorly to two .gwt.xml files in the same Java package:
-     https://goo.gl/pRV3Yn
-     The summary is that it ignores one file in favor of the other.
-     util.concurrent, like nearly all our packages, has two .gwt.xml files: one for prod and one for tests.
-     util.concurrent, unlike our other packages, has, as of this writing, test supersource but no prod supersource.
-     GWT happens to use the prod .gwt.xml, so it looks for no supersource for tests, either.
-     This causes it to fail to find AtomicLongMapTest.
-     Our workaround is to tell GWT that util.concurrent and all other packages have prod supersource, even if they have none.
-     GWT is happy to ignore us when we specify a nonexistent path.
-     (I hope that this workaround does not cause its own problems in the future.)
+    We used to set this only for packages that had manual supersource. That
+    worked everywhere that I know of except for one place: when running the GWT
+    util.concurrent tests under Guava.
+
+    The problem is that GWT responds poorly to two .gwt.xml files in the same
+    Java package; see https://goo.gl/pRV3Yn for details.
+
+    The summary is that it ignores one file in favor of the other.
+    util.concurrent, like nearly all our packages, has two .gwt.xml files: one
+    for prod and one for tests. However, unlike our other packages, as of this
+    writing it has test supersource but no prod supersource.
+
+    GWT happens to use the prod .gwt.xml, so it looks for no supersource for
+    tests, either. This causes it to fail to find AtomicLongMapTest.
+
+    Our workaround is to tell GWT that util.concurrent and all other packages
+    have prod supersource, even if they have none. GWT is happy to ignore us
+    when we specify a nonexistent path.
+
+    (I hope that this workaround does not cause its own problems in the future.)
 -->
 <super-source path="super"/>
-<inherits name="com.google.gwt.user.User" />
 
-<inherits name="com.google.gwt.junit.JUnit" />
 <inherits name="com.google.common.annotations.Annotations" />
 <inherits name="com.google.common.base.Base" />
 <inherits name="com.google.common.collect.Collect" />
-
-
 <inherits name="com.google.gwt.core.Core" />
-
+<inherits name="com.google.gwt.junit.JUnit" />
+<inherits name="com.google.gwt.user.User" />
 </module>
diff --git a/guava-testlib/README.md b/guava-testlib/README.md
index 2f0438dd9a14..d4810e3a34c1 100644
--- a/guava-testlib/README.md
+++ b/guava-testlib/README.md
@@ -13,7 +13,7 @@ To add a dependency on Guava testlib using Maven, use the following:
 <dependency>
   <groupId>com.google.guava</groupId>
   <artifactId>guava-testlib</artifactId>
-  <version>30.1-jre</version>
+  <version>31.1-jre</version>
   <scope>test</scope>
 </dependency>
 ```
@@ -22,7 +22,7 @@ To add a dependency using Gradle:
 
 ```gradle
 dependencies {
-  test 'com.google.guava:guava-testlib:30.1-jre'
+  test 'com.google.guava:guava-testlib:31.1-jre'
 }
 ```
 
diff --git a/guava-testlib/pom.xml b/guava-testlib/pom.xml
index 3cf34f361ff4..19ce18a6049d 100644
--- a/guava-testlib/pom.xml
+++ b/guava-testlib/pom.xml
@@ -5,7 +5,7 @@
   <parent>
     <groupId>com.google.guava</groupId>
     <artifactId>guava-parent</artifactId>
-    <version>30.1.1-jre</version>
+    <version>31.1-jre</version>
   </parent>
   <artifactId>guava-testlib</artifactId>
   <name>Guava Testing Library</name>
diff --git a/guava-testlib/src/com/google/common/collect/testing/AbstractContainerTester.java b/guava-testlib/src/com/google/common/collect/testing/AbstractContainerTester.java
index a5674d3db4d0..b86ef1750dee 100644
--- a/guava-testlib/src/com/google/common/collect/testing/AbstractContainerTester.java
+++ b/guava-testlib/src/com/google/common/collect/testing/AbstractContainerTester.java
@@ -188,7 +188,7 @@ protected ArrayWithDuplicate<E> createArrayWithDuplicateElement() {
     E[] elements = createSamplesArray();
     E duplicate = elements[(elements.length / 2) - 1];
     elements[(elements.length / 2) + 1] = duplicate;
-    return new ArrayWithDuplicate<E>(elements, duplicate);
+    return new ArrayWithDuplicate<>(elements, duplicate);
   }
 
   // Helper methods to improve readability of derived classes
@@ -211,7 +211,7 @@ protected Collection<E> getSampleElements() {
    * requirement {@link com.google.common.collect.testing.features.CollectionFeature#KNOWN_ORDER}.
    */
   protected List<E> getOrderedElements() {
-    List<E> list = new ArrayList<E>();
+    List<E> list = new ArrayList<>();
     for (E e : getSubjectGenerator().order(new ArrayList<E>(getSampleElements()))) {
       list.add(e);
     }
diff --git a/guava-testlib/src/com/google/common/collect/testing/AbstractMapTester.java b/guava-testlib/src/com/google/common/collect/testing/AbstractMapTester.java
index 090442edc4da..5e0de3ccc443 100644
--- a/guava-testlib/src/com/google/common/collect/testing/AbstractMapTester.java
+++ b/guava-testlib/src/com/google/common/collect/testing/AbstractMapTester.java
@@ -72,8 +72,8 @@ protected void expectMissingValues(V... elements) {
   /** @return an array of the proper size with {@code null} as the key of the middle element. */
   protected Entry<K, V>[] createArrayWithNullKey() {
     Entry<K, V>[] array = createSamplesArray();
-    final int nullKeyLocation = getNullLocation();
-    final Entry<K, V> oldEntry = array[nullKeyLocation];
+    int nullKeyLocation = getNullLocation();
+    Entry<K, V> oldEntry = array[nullKeyLocation];
     array[nullKeyLocation] = entry(null, oldEntry.getValue());
     return array;
   }
@@ -97,8 +97,8 @@ private Entry<K, V> getEntryNullReplaces() {
   /** @return an array of the proper size with {@code null} as the value of the middle element. */
   protected Entry<K, V>[] createArrayWithNullValue() {
     Entry<K, V>[] array = createSamplesArray();
-    final int nullValueLocation = getNullLocation();
-    final Entry<K, V> oldEntry = array[nullValueLocation];
+    int nullValueLocation = getNullLocation();
+    Entry<K, V> oldEntry = array[nullValueLocation];
     array[nullValueLocation] = entry(oldEntry.getKey(), null);
     return array;
   }
diff --git a/guava-testlib/src/com/google/common/collect/testing/CollectionTestSuiteBuilder.java b/guava-testlib/src/com/google/common/collect/testing/CollectionTestSuiteBuilder.java
index cf1ed23aa41e..5f9aff4f1c5f 100644
--- a/guava-testlib/src/com/google/common/collect/testing/CollectionTestSuiteBuilder.java
+++ b/guava-testlib/src/com/google/common/collect/testing/CollectionTestSuiteBuilder.java
@@ -57,6 +57,8 @@ protected List<TestSuite> createDerivedSuites(
               .named(getName() + " reserialized")
               .withFeatures(computeReserializedCollectionFeatures(parentBuilder.getFeatures()))
               .suppressing(parentBuilder.getSuppressedTests())
+              .withSetUp(parentBuilder.getSetUp())
+              .withTearDown(parentBuilder.getTearDown())
               .createTestSuite());
     }
     return derivedSuites;
diff --git a/guava-testlib/src/com/google/common/collect/testing/DerivedCollectionGenerators.java b/guava-testlib/src/com/google/common/collect/testing/DerivedCollectionGenerators.java
index 3588e856fa23..a04d3ffe300a 100644
--- a/guava-testlib/src/com/google/common/collect/testing/DerivedCollectionGenerators.java
+++ b/guava-testlib/src/com/google/common/collect/testing/DerivedCollectionGenerators.java
@@ -96,9 +96,9 @@ public static class MapKeySetGenerator<K, V> implements TestSetGenerator<K>, Der
 
     public MapKeySetGenerator(OneSizeTestContainerGenerator<Map<K, V>, Entry<K, V>> mapGenerator) {
       this.mapGenerator = mapGenerator;
-      final SampleElements<Entry<K, V>> mapSamples = this.mapGenerator.samples();
+      SampleElements<Entry<K, V>> mapSamples = this.mapGenerator.samples();
       this.samples =
-          new SampleElements<K>(
+          new SampleElements<>(
               mapSamples.e0().getKey(),
               mapSamples.e1().getKey(),
               mapSamples.e2().getKey(),
@@ -203,9 +203,9 @@ public static class MapValueCollectionGenerator<K, V>
     public MapValueCollectionGenerator(
         OneSizeTestContainerGenerator<Map<K, V>, Entry<K, V>> mapGenerator) {
       this.mapGenerator = mapGenerator;
-      final SampleElements<Entry<K, V>> mapSamples = this.mapGenerator.samples();
+      SampleElements<Entry<K, V>> mapSamples = this.mapGenerator.samples();
       this.samples =
-          new SampleElements<V>(
+          new SampleElements<>(
               mapSamples.e0().getValue(),
               mapSamples.e1().getValue(),
               mapSamples.e2().getValue(),
@@ -239,14 +239,13 @@ public Collection<V> create(Object... elements) {
     @Override
     public V[] createArray(int length) {
       // noinspection UnnecessaryLocalVariable
-      final V[] vs =
-          ((TestMapGenerator<K, V>) mapGenerator.getInnerGenerator()).createValueArray(length);
+      V[] vs = ((TestMapGenerator<K, V>) mapGenerator.getInnerGenerator()).createValueArray(length);
       return vs;
     }
 
     @Override
     public Iterable<V> order(List<V> insertionOrder) {
-      final List<Entry<K, V>> orderedEntries =
+      List<Entry<K, V>> orderedEntries =
           castOrCopyToList(mapGenerator.order(castOrCopyToList(mapGenerator.getSampleElements(5))));
       sort(
           insertionOrder,
diff --git a/guava-testlib/src/com/google/common/collect/testing/FeatureSpecificTestSuiteBuilder.java b/guava-testlib/src/com/google/common/collect/testing/FeatureSpecificTestSuiteBuilder.java
index 0d921a580896..db086aa3075e 100644
--- a/guava-testlib/src/com/google/common/collect/testing/FeatureSpecificTestSuiteBuilder.java
+++ b/guava-testlib/src/com/google/common/collect/testing/FeatureSpecificTestSuiteBuilder.java
@@ -81,7 +81,7 @@ public B withSetUp(Runnable setUp) {
     return self();
   }
 
-  protected Runnable getSetUp() {
+  public Runnable getSetUp() {
     return setUp;
   }
 
@@ -90,13 +90,13 @@ public B withTearDown(Runnable tearDown) {
     return self();
   }
 
-  protected Runnable getTearDown() {
+  public Runnable getTearDown() {
     return tearDown;
   }
 
   // Features
 
-  private Set<Feature<?>> features = new LinkedHashSet<>();
+  private final Set<Feature<?>> features = new LinkedHashSet<>();
 
   /**
    * Configures this builder to produce tests appropriate for the given features. This method may be
@@ -138,7 +138,7 @@ public String getName() {
 
   // Test suppression
 
-  private Set<Method> suppressedTests = new HashSet<>();
+  private final Set<Method> suppressedTests = new HashSet<>();
 
   /**
    * Prevents the given methods from being run as part of the test suite.
@@ -185,7 +185,7 @@ public TestSuite createTestSuite() {
 
     TestSuite suite = new TestSuite(name);
     for (Class<? extends AbstractTester> testerClass : testers) {
-      final TestSuite testerSuite =
+      TestSuite testerSuite =
           makeSuiteForTesterClass((Class<? extends AbstractTester<?>>) testerClass);
       if (testerSuite.countTestCases() > 0) {
         suite.addTest(testerSuite);
@@ -211,7 +211,7 @@ protected void checkCanCreate() {
   protected abstract List<Class<? extends AbstractTester>> getTesters();
 
   private boolean matches(Test test) {
-    final Method method;
+    Method method;
     try {
       method = extractMethod(test);
     } catch (IllegalArgumentException e) {
@@ -222,7 +222,7 @@ private boolean matches(Test test) {
       logger.finer(Platform.format("%s: excluding because it was explicitly suppressed.", test));
       return false;
     }
-    final TesterRequirements requirements;
+    TesterRequirements requirements;
     try {
       requirements = FeatureUtil.getTesterRequirements(method);
     } catch (ConflictingRequirementsException e) {
@@ -268,8 +268,8 @@ private static Method extractMethod(Test test) {
   }
 
   protected TestSuite makeSuiteForTesterClass(Class<? extends AbstractTester<?>> testerClass) {
-    final TestSuite candidateTests = new TestSuite(testerClass);
-    final TestSuite suite = filterSuite(candidateTests);
+    TestSuite candidateTests = new TestSuite(testerClass);
+    TestSuite suite = filterSuite(candidateTests);
 
     Enumeration<?> allTests = suite.tests();
     while (allTests.hasMoreElements()) {
@@ -286,7 +286,7 @@ protected TestSuite makeSuiteForTesterClass(Class<? extends AbstractTester<?>> t
 
   private TestSuite filterSuite(TestSuite suite) {
     TestSuite filtered = new TestSuite(suite.getName());
-    final Enumeration<?> tests = suite.tests();
+    Enumeration<?> tests = suite.tests();
     while (tests.hasMoreElements()) {
       Test test = (Test) tests.nextElement();
       if (matches(test)) {
diff --git a/guava-testlib/src/com/google/common/collect/testing/Helpers.java b/guava-testlib/src/com/google/common/collect/testing/Helpers.java
index 8efafc373525..aac71cc4efe3 100644
--- a/guava-testlib/src/com/google/common/collect/testing/Helpers.java
+++ b/guava-testlib/src/com/google/common/collect/testing/Helpers.java
@@ -49,7 +49,7 @@ static boolean equal(Object a, Object b) {
 
   // Clone of Lists.newArrayList
   public static <E> List<E> copyToList(Iterable<? extends E> elements) {
-    List<E> list = new ArrayList<E>();
+    List<E> list = new ArrayList<>();
     addAll(list, elements);
     return list;
   }
@@ -60,7 +60,7 @@ public static <E> List<E> copyToList(E[] elements) {
 
   // Clone of Sets.newLinkedHashSet
   public static <E> Set<E> copyToSet(Iterable<? extends E> elements) {
-    Set<E> set = new LinkedHashSet<E>();
+    Set<E> set = new LinkedHashSet<>();
     addAll(set, elements);
     return set;
   }
@@ -188,11 +188,11 @@ public static <E> boolean addAll(Collection<E> addTo, Iterable<? extends E> elem
     return modified;
   }
 
-  static <T> Iterable<T> reverse(final List<T> list) {
+  static <T> Iterable<T> reverse(List<T> list) {
     return new Iterable<T>() {
       @Override
       public Iterator<T> iterator() {
-        final ListIterator<T> listIter = list.listIterator(list.size());
+        ListIterator<T> listIter = list.listIterator(list.size());
         return new Iterator<T>() {
           @Override
           public boolean hasNext() {
@@ -213,7 +213,7 @@ public void remove() {
     };
   }
 
-  static <T> Iterator<T> cycle(final Iterable<T> iterable) {
+  static <T> Iterator<T> cycle(Iterable<T> iterable) {
     return new Iterator<T>() {
       Iterator<T> iterator = Collections.<T>emptySet().iterator();
 
@@ -251,7 +251,7 @@ static void fail(Throwable cause, Object message) {
   }
 
   public static <K, V> Comparator<Entry<K, V>> entryComparator(
-      final Comparator<? super K> keyComparator) {
+      Comparator<? super K> keyComparator) {
     return new Comparator<Entry<K, V>>() {
       @Override
       @SuppressWarnings("unchecked") // no less safe than putting it in the map!
@@ -345,7 +345,7 @@ public static <T extends Comparable<? super T>> void testCompareToAndEquals(
    * @param delta the difference between the true size of the collection and the values returned by
    *     the size method
    */
-  public static <T> Collection<T> misleadingSizeCollection(final int delta) {
+  public static <T> Collection<T> misleadingSizeCollection(int delta) {
     // It would be nice to be able to return a real concurrent
     // collection like ConcurrentLinkedQueue, so that e.g. concurrent
     // iteration would work, but that would not be GWT-compatible.
@@ -363,7 +363,7 @@ public int size() {
    * equals. This is used for testing unmodifiable collections of map entries; for example, it
    * should not be possible to access the raw (modifiable) map entry via a nefarious equals method.
    */
-  public static <K, V> Entry<K, V> nefariousMapEntry(final K key, final V value) {
+  public static <K, V> Entry<K, V> nefariousMapEntry(K key, V value) {
     return new Entry<K, V>() {
       @Override
       public K getKey() {
@@ -410,7 +410,7 @@ static <E> List<E> castOrCopyToList(Iterable<E> iterable) {
     if (iterable instanceof List) {
       return (List<E>) iterable;
     }
-    List<E> list = new ArrayList<E>();
+    List<E> list = new ArrayList<>();
     for (E e : iterable) {
       list.add(e);
     }
diff --git a/guava-testlib/src/com/google/common/collect/testing/ListTestSuiteBuilder.java b/guava-testlib/src/com/google/common/collect/testing/ListTestSuiteBuilder.java
index 5355f483d642..492a50c491ec 100644
--- a/guava-testlib/src/com/google/common/collect/testing/ListTestSuiteBuilder.java
+++ b/guava-testlib/src/com/google/common/collect/testing/ListTestSuiteBuilder.java
@@ -114,6 +114,8 @@ protected List<TestSuite> createDerivedSuites(
               .named(getName() + " reserialized")
               .withFeatures(computeReserializedCollectionFeatures(parentBuilder.getFeatures()))
               .suppressing(parentBuilder.getSuppressedTests())
+              .withSetUp(parentBuilder.getSetUp())
+              .withTearDown(parentBuilder.getTearDown())
               .createTestSuite());
     }
     return derivedSuites;
diff --git a/guava-testlib/src/com/google/common/collect/testing/MapInterfaceTest.java b/guava-testlib/src/com/google/common/collect/testing/MapInterfaceTest.java
index b8b5c28fb936..48491387851f 100644
--- a/guava-testlib/src/com/google/common/collect/testing/MapInterfaceTest.java
+++ b/guava-testlib/src/com/google/common/collect/testing/MapInterfaceTest.java
@@ -149,7 +149,7 @@ protected final boolean supportsValuesHashCode(Map<K, V> map) {
     for (V value : values) {
       if (value != null) {
         try {
-          value.hashCode();
+          int unused = value.hashCode();
         } catch (Exception e) {
           return false;
         }
@@ -265,7 +265,7 @@ private void assertEntrySetNotContainsString(Set<Entry<K, V>> entrySet) {
   protected void assertMoreInvariants(Map<K, V> map) {}
 
   public void testClear() {
-    final Map<K, V> map;
+    Map<K, V> map;
     try {
       map = makePopulatedMap();
     } catch (UnsupportedOperationException e) {
@@ -286,8 +286,8 @@ public void testClear() {
   }
 
   public void testContainsKey() {
-    final Map<K, V> map;
-    final K unmappedKey;
+    Map<K, V> map;
+    K unmappedKey;
     try {
       map = makePopulatedMap();
       unmappedKey = getKeyNotInPopulatedMap();
@@ -312,8 +312,8 @@ public void testContainsKey() {
   }
 
   public void testContainsValue() {
-    final Map<K, V> map;
-    final V unmappedValue;
+    Map<K, V> map;
+    V unmappedValue;
     try {
       map = makePopulatedMap();
       unmappedValue = getValueNotInPopulatedMap();
@@ -334,8 +334,8 @@ public void testContainsValue() {
   }
 
   public void testEntrySet() {
-    final Map<K, V> map;
-    final Set<Entry<K, V>> entrySet;
+    Map<K, V> map;
+    Set<Entry<K, V>> entrySet;
     try {
       map = makePopulatedMap();
     } catch (UnsupportedOperationException e) {
@@ -344,8 +344,8 @@ public void testEntrySet() {
     assertInvariants(map);
 
     entrySet = map.entrySet();
-    final K unmappedKey;
-    final V unmappedValue;
+    K unmappedKey;
+    V unmappedValue;
     try {
       unmappedKey = getKeyNotInPopulatedMap();
       unmappedValue = getValueNotInPopulatedMap();
@@ -359,7 +359,7 @@ public void testEntrySet() {
   }
 
   public void testEntrySetForEmptyMap() {
-    final Map<K, V> map;
+    Map<K, V> map;
     try {
       map = makeEmptyMap();
     } catch (UnsupportedOperationException e) {
@@ -369,8 +369,8 @@ public void testEntrySetForEmptyMap() {
   }
 
   public void testEntrySetContainsEntryIncompatibleKey() {
-    final Map<K, V> map;
-    final Set<Entry<K, V>> entrySet;
+    Map<K, V> map;
+    Set<Entry<K, V>> entrySet;
     try {
       map = makeEitherMap();
     } catch (UnsupportedOperationException e) {
@@ -379,7 +379,7 @@ public void testEntrySetContainsEntryIncompatibleKey() {
     assertInvariants(map);
 
     entrySet = map.entrySet();
-    final V unmappedValue;
+    V unmappedValue;
     try {
       unmappedValue = getValueNotInPopulatedMap();
     } catch (UnsupportedOperationException e) {
@@ -396,8 +396,8 @@ public void testEntrySetContainsEntryNullKeyPresent() {
     if (!allowsNullKeys || !supportsPut) {
       return;
     }
-    final Map<K, V> map;
-    final Set<Entry<K, V>> entrySet;
+    Map<K, V> map;
+    Set<Entry<K, V>> entrySet;
     try {
       map = makeEitherMap();
     } catch (UnsupportedOperationException e) {
@@ -406,7 +406,7 @@ public void testEntrySetContainsEntryNullKeyPresent() {
     assertInvariants(map);
 
     entrySet = map.entrySet();
-    final V unmappedValue;
+    V unmappedValue;
     try {
       unmappedValue = getValueNotInPopulatedMap();
     } catch (UnsupportedOperationException e) {
@@ -420,8 +420,8 @@ public void testEntrySetContainsEntryNullKeyPresent() {
   }
 
   public void testEntrySetContainsEntryNullKeyMissing() {
-    final Map<K, V> map;
-    final Set<Entry<K, V>> entrySet;
+    Map<K, V> map;
+    Set<Entry<K, V>> entrySet;
     try {
       map = makeEitherMap();
     } catch (UnsupportedOperationException e) {
@@ -430,7 +430,7 @@ public void testEntrySetContainsEntryNullKeyMissing() {
     assertInvariants(map);
 
     entrySet = map.entrySet();
-    final V unmappedValue;
+    V unmappedValue;
     try {
       unmappedValue = getValueNotInPopulatedMap();
     } catch (UnsupportedOperationException e) {
@@ -450,7 +450,7 @@ public void testEntrySetContainsEntryNullKeyMissing() {
   }
 
   public void testEntrySetIteratorRemove() {
-    final Map<K, V> map;
+    Map<K, V> map;
     try {
       map = makePopulatedMap();
     } catch (UnsupportedOperationException e) {
@@ -488,7 +488,7 @@ public void testEntrySetIteratorRemove() {
   }
 
   public void testEntrySetRemove() {
-    final Map<K, V> map;
+    Map<K, V> map;
     try {
       map = makePopulatedMap();
     } catch (UnsupportedOperationException e) {
@@ -512,8 +512,8 @@ public void testEntrySetRemove() {
   }
 
   public void testEntrySetRemoveMissingKey() {
-    final Map<K, V> map;
-    final K key;
+    Map<K, V> map;
+    K key;
     try {
       map = makeEitherMap();
       key = getKeyNotInPopulatedMap();
@@ -540,7 +540,7 @@ public void testEntrySetRemoveMissingKey() {
   }
 
   public void testEntrySetRemoveDifferentValue() {
-    final Map<K, V> map;
+    Map<K, V> map;
     try {
       map = makePopulatedMap();
     } catch (UnsupportedOperationException e) {
@@ -570,8 +570,8 @@ public void testEntrySetRemoveNullKeyPresent() {
     if (!allowsNullKeys || !supportsPut || !supportsRemove) {
       return;
     }
-    final Map<K, V> map;
-    final Set<Entry<K, V>> entrySet;
+    Map<K, V> map;
+    Set<Entry<K, V>> entrySet;
     try {
       map = makeEitherMap();
     } catch (UnsupportedOperationException e) {
@@ -580,7 +580,7 @@ public void testEntrySetRemoveNullKeyPresent() {
     assertInvariants(map);
 
     entrySet = map.entrySet();
-    final V unmappedValue;
+    V unmappedValue;
     try {
       unmappedValue = getValueNotInPopulatedMap();
     } catch (UnsupportedOperationException e) {
@@ -597,7 +597,7 @@ public void testEntrySetRemoveNullKeyPresent() {
   }
 
   public void testEntrySetRemoveNullKeyMissing() {
-    final Map<K, V> map;
+    Map<K, V> map;
     try {
       map = makeEitherMap();
     } catch (UnsupportedOperationException e) {
@@ -626,7 +626,7 @@ public void testEntrySetRemoveNullKeyMissing() {
   }
 
   public void testEntrySetRemoveAll() {
-    final Map<K, V> map;
+    Map<K, V> map;
     try {
       map = makePopulatedMap();
     } catch (UnsupportedOperationException e) {
@@ -663,7 +663,7 @@ public void testEntrySetRemoveAll() {
   }
 
   public void testEntrySetRemoveAllNullFromEmpty() {
-    final Map<K, V> map;
+    Map<K, V> map;
     try {
       map = makeEmptyMap();
     } catch (UnsupportedOperationException e) {
@@ -689,7 +689,7 @@ public void testEntrySetRemoveAllNullFromEmpty() {
   }
 
   public void testEntrySetRetainAll() {
-    final Map<K, V> map;
+    Map<K, V> map;
     try {
       map = makePopulatedMap();
     } catch (UnsupportedOperationException e) {
@@ -717,7 +717,7 @@ public void testEntrySetRetainAll() {
   }
 
   public void testEntrySetRetainAllNullFromEmpty() {
-    final Map<K, V> map;
+    Map<K, V> map;
     try {
       map = makeEmptyMap();
     } catch (UnsupportedOperationException e) {
@@ -743,7 +743,7 @@ public void testEntrySetRetainAllNullFromEmpty() {
   }
 
   public void testEntrySetClear() {
-    final Map<K, V> map;
+    Map<K, V> map;
     try {
       map = makePopulatedMap();
     } catch (UnsupportedOperationException e) {
@@ -765,10 +765,10 @@ public void testEntrySetClear() {
   }
 
   public void testEntrySetAddAndAddAll() {
-    final Map<K, V> map = makeEitherMap();
+    Map<K, V> map = makeEitherMap();
 
     Set<Entry<K, V>> entrySet = map.entrySet();
-    final Entry<K, V> entryToAdd = mapEntry(null, null);
+    Entry<K, V> entryToAdd = mapEntry(null, null);
     try {
       entrySet.add(entryToAdd);
       fail("Expected UnsupportedOperationException or NullPointerException.");
@@ -793,8 +793,8 @@ public void testEntrySetSetValue() {
       return;
     }
 
-    final Map<K, V> map;
-    final V valueToSet;
+    Map<K, V> map;
+    V valueToSet;
     try {
       map = makePopulatedMap();
       valueToSet = getValueNotInPopulatedMap();
@@ -804,8 +804,8 @@ public void testEntrySetSetValue() {
 
     Set<Entry<K, V>> entrySet = map.entrySet();
     Entry<K, V> entry = entrySet.iterator().next();
-    final V oldValue = entry.getValue();
-    final V returnedValue = entry.setValue(valueToSet);
+    V oldValue = entry.getValue();
+    V returnedValue = entry.setValue(valueToSet);
     assertEquals(oldValue, returnedValue);
     assertTrue(entrySet.contains(mapEntry(entry.getKey(), valueToSet)));
     assertEquals(valueToSet, map.get(entry.getKey()));
@@ -819,7 +819,7 @@ public void testEntrySetSetValueSameValue() {
       return;
     }
 
-    final Map<K, V> map;
+    Map<K, V> map;
     try {
       map = makePopulatedMap();
     } catch (UnsupportedOperationException e) {
@@ -828,8 +828,8 @@ public void testEntrySetSetValueSameValue() {
 
     Set<Entry<K, V>> entrySet = map.entrySet();
     Entry<K, V> entry = entrySet.iterator().next();
-    final V oldValue = entry.getValue();
-    final V returnedValue = entry.setValue(oldValue);
+    V oldValue = entry.getValue();
+    V returnedValue = entry.setValue(oldValue);
     assertEquals(oldValue, returnedValue);
     assertTrue(entrySet.contains(mapEntry(entry.getKey(), oldValue)));
     assertEquals(oldValue, map.get(entry.getKey()));
@@ -837,15 +837,16 @@ public void testEntrySetSetValueSameValue() {
   }
 
   public void testEqualsForEqualMap() {
-    final Map<K, V> map;
+    Map<K, V> map;
     try {
       map = makePopulatedMap();
     } catch (UnsupportedOperationException e) {
       return;
     }
 
-    assertEquals(map, map);
-    assertEquals(makePopulatedMap(), map);
+    // Explicitly call `equals`; `assertEquals` might return fast
+    assertTrue(map.equals(map));
+    assertTrue(makePopulatedMap().equals(map));
     assertFalse(map.equals(Collections.emptyMap()));
     // no-inspection ObjectEqualsNull
     assertFalse(map.equals(null));
@@ -856,8 +857,8 @@ public void testEqualsForLargerMap() {
       return;
     }
 
-    final Map<K, V> map;
-    final Map<K, V> largerMap;
+    Map<K, V> map;
+    Map<K, V> largerMap;
     try {
       map = makePopulatedMap();
       largerMap = makePopulatedMap();
@@ -874,8 +875,8 @@ public void testEqualsForSmallerMap() {
       return;
     }
 
-    final Map<K, V> map;
-    final Map<K, V> smallerMap;
+    Map<K, V> map;
+    Map<K, V> smallerMap;
     try {
       map = makePopulatedMap();
       smallerMap = makePopulatedMap();
@@ -888,15 +889,16 @@ public void testEqualsForSmallerMap() {
   }
 
   public void testEqualsForEmptyMap() {
-    final Map<K, V> map;
+    Map<K, V> map;
     try {
       map = makeEmptyMap();
     } catch (UnsupportedOperationException e) {
       return;
     }
 
-    assertEquals(map, map);
-    assertEquals(makeEmptyMap(), map);
+    // Explicitly call `equals`; `assertEquals` might return fast
+    assertTrue(map.equals(map));
+    assertTrue(makeEmptyMap().equals(map));
     assertEquals(Collections.emptyMap(), map);
     assertFalse(map.equals(Collections.emptySet()));
     // noinspection ObjectEqualsNull
@@ -904,7 +906,7 @@ public void testEqualsForEmptyMap() {
   }
 
   public void testGet() {
-    final Map<K, V> map;
+    Map<K, V> map;
     try {
       map = makePopulatedMap();
     } catch (UnsupportedOperationException e) {
@@ -925,7 +927,7 @@ public void testGet() {
   }
 
   public void testGetForEmptyMap() {
-    final Map<K, V> map;
+    Map<K, V> map;
     K unmappedKey = null;
     try {
       map = makeEmptyMap();
@@ -954,7 +956,7 @@ public void testGetNull() {
   }
 
   public void testHashCode() {
-    final Map<K, V> map;
+    Map<K, V> map;
     try {
       map = makePopulatedMap();
     } catch (UnsupportedOperationException e) {
@@ -964,7 +966,7 @@ public void testHashCode() {
   }
 
   public void testHashCodeForEmptyMap() {
-    final Map<K, V> map;
+    Map<K, V> map;
     try {
       map = makeEmptyMap();
     } catch (UnsupportedOperationException e) {
@@ -974,9 +976,9 @@ public void testHashCodeForEmptyMap() {
   }
 
   public void testPutNewKey() {
-    final Map<K, V> map = makeEitherMap();
-    final K keyToPut;
-    final V valueToPut;
+    Map<K, V> map = makeEitherMap();
+    K keyToPut;
+    V valueToPut;
     try {
       keyToPut = getKeyNotInPopulatedMap();
       valueToPut = getValueNotInPopulatedMap();
@@ -1002,9 +1004,9 @@ public void testPutNewKey() {
   }
 
   public void testPutExistingKey() {
-    final Map<K, V> map;
-    final K keyToPut;
-    final V valueToPut;
+    Map<K, V> map;
+    K keyToPut;
+    V valueToPut;
     try {
       map = makePopulatedMap();
       valueToPut = getValueNotInPopulatedMap();
@@ -1033,16 +1035,16 @@ public void testPutNullKey() {
     if (!supportsPut) {
       return;
     }
-    final Map<K, V> map = makeEitherMap();
-    final V valueToPut;
+    Map<K, V> map = makeEitherMap();
+    V valueToPut;
     try {
       valueToPut = getValueNotInPopulatedMap();
     } catch (UnsupportedOperationException e) {
       return;
     }
     if (allowsNullKeys) {
-      final V oldValue = map.get(null);
-      final V returnedValue = map.put(null, valueToPut);
+      V oldValue = map.get(null);
+      V returnedValue = map.put(null, valueToPut);
       assertEquals(oldValue, returnedValue);
       assertEquals(valueToPut, map.get(null));
       assertTrue(map.containsKey(null));
@@ -1061,8 +1063,8 @@ public void testPutNullValue() {
     if (!supportsPut) {
       return;
     }
-    final Map<K, V> map = makeEitherMap();
-    final K keyToPut;
+    Map<K, V> map = makeEitherMap();
+    K keyToPut;
     try {
       keyToPut = getKeyNotInPopulatedMap();
     } catch (UnsupportedOperationException e) {
@@ -1070,8 +1072,8 @@ public void testPutNullValue() {
     }
     if (allowsNullValues) {
       int initialSize = map.size();
-      final V oldValue = map.get(keyToPut);
-      final V returnedValue = map.put(keyToPut, null);
+      V oldValue = map.get(keyToPut);
+      V returnedValue = map.put(keyToPut, null);
       assertEquals(oldValue, returnedValue);
       assertNull(map.get(keyToPut));
       assertTrue(map.containsKey(keyToPut));
@@ -1091,8 +1093,8 @@ public void testPutNullValueForExistingKey() {
     if (!supportsPut) {
       return;
     }
-    final Map<K, V> map;
-    final K keyToPut;
+    Map<K, V> map;
+    K keyToPut;
     try {
       map = makePopulatedMap();
       keyToPut = map.keySet().iterator().next();
@@ -1101,8 +1103,8 @@ public void testPutNullValueForExistingKey() {
     }
     if (allowsNullValues) {
       int initialSize = map.size();
-      final V oldValue = map.get(keyToPut);
-      final V returnedValue = map.put(keyToPut, null);
+      V oldValue = map.get(keyToPut);
+      V returnedValue = map.put(keyToPut, null);
       assertEquals(oldValue, returnedValue);
       assertNull(map.get(keyToPut));
       assertTrue(map.containsKey(keyToPut));
@@ -1119,16 +1121,16 @@ public void testPutNullValueForExistingKey() {
   }
 
   public void testPutAllNewKey() {
-    final Map<K, V> map = makeEitherMap();
-    final K keyToPut;
-    final V valueToPut;
+    Map<K, V> map = makeEitherMap();
+    K keyToPut;
+    V valueToPut;
     try {
       keyToPut = getKeyNotInPopulatedMap();
       valueToPut = getValueNotInPopulatedMap();
     } catch (UnsupportedOperationException e) {
       return;
     }
-    final Map<K, V> mapToPut = Collections.singletonMap(keyToPut, valueToPut);
+    Map<K, V> mapToPut = Collections.singletonMap(keyToPut, valueToPut);
     if (supportsPut) {
       int initialSize = map.size();
       map.putAll(mapToPut);
@@ -1147,9 +1149,9 @@ public void testPutAllNewKey() {
   }
 
   public void testPutAllExistingKey() {
-    final Map<K, V> map;
-    final K keyToPut;
-    final V valueToPut;
+    Map<K, V> map;
+    K keyToPut;
+    V valueToPut;
     try {
       map = makePopulatedMap();
       valueToPut = getValueNotInPopulatedMap();
@@ -1157,7 +1159,7 @@ public void testPutAllExistingKey() {
       return;
     }
     keyToPut = map.keySet().iterator().next();
-    final Map<K, V> mapToPut = Collections.singletonMap(keyToPut, valueToPut);
+    Map<K, V> mapToPut = Collections.singletonMap(keyToPut, valueToPut);
     int initialSize = map.size();
     if (supportsPut) {
       map.putAll(mapToPut);
@@ -1176,8 +1178,8 @@ public void testPutAllExistingKey() {
   }
 
   public void testRemove() {
-    final Map<K, V> map;
-    final K keyToRemove;
+    Map<K, V> map;
+    K keyToRemove;
     try {
       map = makePopulatedMap();
     } catch (UnsupportedOperationException e) {
@@ -1202,8 +1204,8 @@ public void testRemove() {
   }
 
   public void testRemoveMissingKey() {
-    final Map<K, V> map;
-    final K keyToRemove;
+    Map<K, V> map;
+    K keyToRemove;
     try {
       map = makePopulatedMap();
       keyToRemove = getKeyNotInPopulatedMap();
@@ -1229,7 +1231,7 @@ public void testSize() {
   }
 
   public void testKeySetRemove() {
-    final Map<K, V> map;
+    Map<K, V> map;
     try {
       map = makePopulatedMap();
     } catch (UnsupportedOperationException e) {
@@ -1254,7 +1256,7 @@ public void testKeySetRemove() {
   }
 
   public void testKeySetRemoveAll() {
-    final Map<K, V> map;
+    Map<K, V> map;
     try {
       map = makePopulatedMap();
     } catch (UnsupportedOperationException e) {
@@ -1279,7 +1281,7 @@ public void testKeySetRemoveAll() {
   }
 
   public void testKeySetRetainAll() {
-    final Map<K, V> map;
+    Map<K, V> map;
     try {
       map = makePopulatedMap();
     } catch (UnsupportedOperationException e) {
@@ -1303,7 +1305,7 @@ public void testKeySetRetainAll() {
   }
 
   public void testKeySetClear() {
-    final Map<K, V> map;
+    Map<K, V> map;
     try {
       map = makeEitherMap();
     } catch (UnsupportedOperationException e) {
@@ -1325,7 +1327,7 @@ public void testKeySetClear() {
   }
 
   public void testKeySetRemoveAllNullFromEmpty() {
-    final Map<K, V> map;
+    Map<K, V> map;
     try {
       map = makeEmptyMap();
     } catch (UnsupportedOperationException e) {
@@ -1351,7 +1353,7 @@ public void testKeySetRemoveAllNullFromEmpty() {
   }
 
   public void testKeySetRetainAllNullFromEmpty() {
-    final Map<K, V> map;
+    Map<K, V> map;
     try {
       map = makeEmptyMap();
     } catch (UnsupportedOperationException e) {
@@ -1377,8 +1379,8 @@ public void testKeySetRetainAllNullFromEmpty() {
   }
 
   public void testValues() {
-    final Map<K, V> map;
-    final Collection<V> valueCollection;
+    Map<K, V> map;
+    Collection<V> valueCollection;
     try {
       map = makePopulatedMap();
     } catch (UnsupportedOperationException e) {
@@ -1387,7 +1389,7 @@ public void testValues() {
     assertInvariants(map);
 
     valueCollection = map.values();
-    final V unmappedValue;
+    V unmappedValue;
     try {
       unmappedValue = getValueNotInPopulatedMap();
     } catch (UnsupportedOperationException e) {
@@ -1399,7 +1401,7 @@ public void testValues() {
   }
 
   public void testValuesIteratorRemove() {
-    final Map<K, V> map;
+    Map<K, V> map;
     try {
       map = makePopulatedMap();
     } catch (UnsupportedOperationException e) {
@@ -1434,7 +1436,7 @@ public void testValuesIteratorRemove() {
   }
 
   public void testValuesRemove() {
-    final Map<K, V> map;
+    Map<K, V> map;
     try {
       map = makePopulatedMap();
     } catch (UnsupportedOperationException e) {
@@ -1460,8 +1462,8 @@ public void testValuesRemove() {
   }
 
   public void testValuesRemoveMissing() {
-    final Map<K, V> map;
-    final V valueToRemove;
+    Map<K, V> map;
+    V valueToRemove;
     try {
       map = makeEitherMap();
       valueToRemove = getValueNotInPopulatedMap();
@@ -1485,7 +1487,7 @@ public void testValuesRemoveMissing() {
   }
 
   public void testValuesRemoveAll() {
-    final Map<K, V> map;
+    Map<K, V> map;
     try {
       map = makePopulatedMap();
     } catch (UnsupportedOperationException e) {
@@ -1513,7 +1515,7 @@ public void testValuesRemoveAll() {
   }
 
   public void testValuesRemoveAllNullFromEmpty() {
-    final Map<K, V> map;
+    Map<K, V> map;
     try {
       map = makeEmptyMap();
     } catch (UnsupportedOperationException e) {
@@ -1539,7 +1541,7 @@ public void testValuesRemoveAllNullFromEmpty() {
   }
 
   public void testValuesRetainAll() {
-    final Map<K, V> map;
+    Map<K, V> map;
     try {
       map = makePopulatedMap();
     } catch (UnsupportedOperationException e) {
@@ -1567,7 +1569,7 @@ public void testValuesRetainAll() {
   }
 
   public void testValuesRetainAllNullFromEmpty() {
-    final Map<K, V> map;
+    Map<K, V> map;
     try {
       map = makeEmptyMap();
     } catch (UnsupportedOperationException e) {
@@ -1593,7 +1595,7 @@ public void testValuesRetainAllNullFromEmpty() {
   }
 
   public void testValuesClear() {
-    final Map<K, V> map;
+    Map<K, V> map;
     try {
       map = makePopulatedMap();
     } catch (UnsupportedOperationException e) {
diff --git a/guava-testlib/src/com/google/common/collect/testing/MapTestSuiteBuilder.java b/guava-testlib/src/com/google/common/collect/testing/MapTestSuiteBuilder.java
index 0b02f3b78419..d1ce3413dd78 100644
--- a/guava-testlib/src/com/google/common/collect/testing/MapTestSuiteBuilder.java
+++ b/guava-testlib/src/com/google/common/collect/testing/MapTestSuiteBuilder.java
@@ -123,6 +123,8 @@ protected List<TestSuite> createDerivedSuites(
               .withFeatures(computeReserializedMapFeatures(parentBuilder.getFeatures()))
               .named(parentBuilder.getName() + " reserialized")
               .suppressing(parentBuilder.getSuppressedTests())
+              .withSetUp(parentBuilder.getSetUp())
+              .withTearDown(parentBuilder.getTearDown())
               .createTestSuite());
     }
 
@@ -132,6 +134,8 @@ protected List<TestSuite> createDerivedSuites(
             .withFeatures(computeEntrySetFeatures(parentBuilder.getFeatures()))
             .named(parentBuilder.getName() + " entrySet")
             .suppressing(parentBuilder.getSuppressedTests())
+            .withSetUp(parentBuilder.getSetUp())
+            .withTearDown(parentBuilder.getTearDown())
             .createTestSuite());
 
     derivedSuites.add(
@@ -139,6 +143,8 @@ protected List<TestSuite> createDerivedSuites(
             .withFeatures(computeKeySetFeatures(parentBuilder.getFeatures()))
             .named(parentBuilder.getName() + " keys")
             .suppressing(parentBuilder.getSuppressedTests())
+            .withSetUp(parentBuilder.getSetUp())
+            .withTearDown(parentBuilder.getTearDown())
             .createTestSuite());
 
     derivedSuites.add(
@@ -147,6 +153,8 @@ protected List<TestSuite> createDerivedSuites(
             .named(parentBuilder.getName() + " values")
             .withFeatures(computeValuesCollectionFeatures(parentBuilder.getFeatures()))
             .suppressing(parentBuilder.getSuppressedTests())
+            .withSetUp(parentBuilder.getSetUp())
+            .withTearDown(parentBuilder.getTearDown())
             .createTestSuite());
 
     return derivedSuites;
diff --git a/guava-testlib/src/com/google/common/collect/testing/MinimalCollection.java b/guava-testlib/src/com/google/common/collect/testing/MinimalCollection.java
index a6ec93d1eca3..2adf0725147d 100644
--- a/guava-testlib/src/com/google/common/collect/testing/MinimalCollection.java
+++ b/guava-testlib/src/com/google/common/collect/testing/MinimalCollection.java
@@ -33,12 +33,12 @@ public class MinimalCollection<E> extends AbstractCollection<E> {
   // TODO: expose allow nulls parameter?
 
   public static <E> MinimalCollection<E> of(E... contents) {
-    return new MinimalCollection<E>(Object.class, true, contents);
+    return new MinimalCollection<>(Object.class, true, contents);
   }
 
   // TODO: use this
   public static <E> MinimalCollection<E> ofClassAndContents(Class<? super E> type, E... contents) {
-    return new MinimalCollection<E>(type, true, contents);
+    return new MinimalCollection<>(type, true, contents);
   }
 
   private final E[] contents;
diff --git a/guava-testlib/src/com/google/common/collect/testing/MinimalIterable.java b/guava-testlib/src/com/google/common/collect/testing/MinimalIterable.java
index c151c15e1319..15d48dbbd75b 100644
--- a/guava-testlib/src/com/google/common/collect/testing/MinimalIterable.java
+++ b/guava-testlib/src/com/google/common/collect/testing/MinimalIterable.java
@@ -51,7 +51,7 @@ public final class MinimalIterable<E> implements Iterable<E> {
   /** Returns an iterable whose iterator returns the given elements in order. */
   public static <E> MinimalIterable<E> of(E... elements) {
     // Make sure to get an unmodifiable iterator
-    return new MinimalIterable<E>(Arrays.asList(elements).iterator());
+    return new MinimalIterable<>(Arrays.asList(elements).iterator());
   }
 
   /**
@@ -59,7 +59,7 @@ public static <E> MinimalIterable<E> of(E... elements) {
    * out of the source collection at the time this method is called.
    */
   @SuppressWarnings("unchecked") // Es come in, Es go out
-  public static <E> MinimalIterable<E> from(final Collection<E> elements) {
+  public static <E> MinimalIterable<E> from(Collection<E> elements) {
     return (MinimalIterable) of(elements.toArray());
   }
 
diff --git a/guava-testlib/src/com/google/common/collect/testing/MinimalSet.java b/guava-testlib/src/com/google/common/collect/testing/MinimalSet.java
index 988dd3f95511..9a87d244d01f 100644
--- a/guava-testlib/src/com/google/common/collect/testing/MinimalSet.java
+++ b/guava-testlib/src/com/google/common/collect/testing/MinimalSet.java
@@ -45,13 +45,13 @@ public static <E> MinimalSet<E> from(Collection<? extends E> contents) {
 
   public static <E> MinimalSet<E> ofClassAndContents(
       Class<? super E> type, E[] emptyArrayForContents, Iterable<? extends E> contents) {
-    List<E> setContents = new ArrayList<E>();
+    List<E> setContents = new ArrayList<>();
     for (E e : contents) {
       if (!setContents.contains(e)) {
         setContents.add(e);
       }
     }
-    return new MinimalSet<E>(type, setContents.toArray(emptyArrayForContents));
+    return new MinimalSet<>(type, setContents.toArray(emptyArrayForContents));
   }
 
   private MinimalSet(Class<? super E> type, E... contents) {
diff --git a/guava-testlib/src/com/google/common/collect/testing/NavigableMapTestSuiteBuilder.java b/guava-testlib/src/com/google/common/collect/testing/NavigableMapTestSuiteBuilder.java
index 77a198454bd8..0e1a229208e8 100644
--- a/guava-testlib/src/com/google/common/collect/testing/NavigableMapTestSuiteBuilder.java
+++ b/guava-testlib/src/com/google/common/collect/testing/NavigableMapTestSuiteBuilder.java
@@ -116,10 +116,10 @@ public NavigableMapTestSuiteBuilder<K, V> newBuilderUsing(
 
   /** Create a suite whose maps are descending views of other maps. */
   private TestSuite createDescendingSuite(
-      final FeatureSpecificTestSuiteBuilder<
+      FeatureSpecificTestSuiteBuilder<
               ?, ? extends OneSizeTestContainerGenerator<Map<K, V>, Entry<K, V>>>
           parentBuilder) {
-    final TestSortedMapGenerator<K, V> delegate =
+    TestSortedMapGenerator<K, V> delegate =
         (TestSortedMapGenerator<K, V>) parentBuilder.getSubjectGenerator().getInnerGenerator();
 
     List<Feature<?>> features = new ArrayList<>();
diff --git a/guava-testlib/src/com/google/common/collect/testing/NavigableSetTestSuiteBuilder.java b/guava-testlib/src/com/google/common/collect/testing/NavigableSetTestSuiteBuilder.java
index 38eb56e09dee..4c86ab46206c 100644
--- a/guava-testlib/src/com/google/common/collect/testing/NavigableSetTestSuiteBuilder.java
+++ b/guava-testlib/src/com/google/common/collect/testing/NavigableSetTestSuiteBuilder.java
@@ -40,7 +40,7 @@
 @GwtIncompatible
 public final class NavigableSetTestSuiteBuilder<E> extends SortedSetTestSuiteBuilder<E> {
   public static <E> NavigableSetTestSuiteBuilder<E> using(TestSortedSetGenerator<E> generator) {
-    NavigableSetTestSuiteBuilder<E> builder = new NavigableSetTestSuiteBuilder<E>();
+    NavigableSetTestSuiteBuilder<E> builder = new NavigableSetTestSuiteBuilder<>();
     builder.usingGenerator(generator);
     return builder;
   }
@@ -99,10 +99,9 @@ public NavigableSetTestSuiteBuilder<E> newBuilderUsing(
 
   /** Create a suite whose maps are descending views of other maps. */
   private TestSuite createDescendingSuite(
-      final FeatureSpecificTestSuiteBuilder<
-              ?, ? extends OneSizeTestContainerGenerator<Collection<E>, E>>
+      FeatureSpecificTestSuiteBuilder<?, ? extends OneSizeTestContainerGenerator<Collection<E>, E>>
           parentBuilder) {
-    final TestSetGenerator<E> delegate =
+    TestSetGenerator<E> delegate =
         (TestSetGenerator<E>) parentBuilder.getSubjectGenerator().getInnerGenerator();
 
     List<Feature<?>> features = new ArrayList<>();
@@ -124,7 +123,7 @@ public E[] createArray(int length) {
 
               @Override
               public Iterable<E> order(List<E> insertionOrder) {
-                List<E> list = new ArrayList<E>();
+                List<E> list = new ArrayList<>();
                 for (E e : delegate.order(insertionOrder)) {
                   list.add(e);
                 }
diff --git a/guava-testlib/src/com/google/common/collect/testing/OneSizeGenerator.java b/guava-testlib/src/com/google/common/collect/testing/OneSizeGenerator.java
index 1b8924c07606..1ff3facc4fd4 100644
--- a/guava-testlib/src/com/google/common/collect/testing/OneSizeGenerator.java
+++ b/guava-testlib/src/com/google/common/collect/testing/OneSizeGenerator.java
@@ -70,7 +70,7 @@ public Collection<E> getSampleElements(int howMany) {
     @SuppressWarnings("unchecked")
     List<E> allSampleElements =
         Arrays.asList(samples.e0(), samples.e1(), samples.e2(), samples.e3(), samples.e4());
-    return new ArrayList<E>(allSampleElements.subList(0, howMany));
+    return new ArrayList<>(allSampleElements.subList(0, howMany));
   }
 
   @Override
diff --git a/guava-testlib/src/com/google/common/collect/testing/ReserializingTestCollectionGenerator.java b/guava-testlib/src/com/google/common/collect/testing/ReserializingTestCollectionGenerator.java
index 28d6f7917dd9..923f56fd45c0 100644
--- a/guava-testlib/src/com/google/common/collect/testing/ReserializingTestCollectionGenerator.java
+++ b/guava-testlib/src/com/google/common/collect/testing/ReserializingTestCollectionGenerator.java
@@ -42,7 +42,7 @@ public class ReserializingTestCollectionGenerator<E> implements TestCollectionGe
 
   public static <E> ReserializingTestCollectionGenerator<E> newInstance(
       TestCollectionGenerator<E> delegate) {
-    return new ReserializingTestCollectionGenerator<E>(delegate);
+    return new ReserializingTestCollectionGenerator<>(delegate);
   }
 
   @Override
diff --git a/guava-testlib/src/com/google/common/collect/testing/ReserializingTestSetGenerator.java b/guava-testlib/src/com/google/common/collect/testing/ReserializingTestSetGenerator.java
index c92a3ff20aca..555440adc172 100644
--- a/guava-testlib/src/com/google/common/collect/testing/ReserializingTestSetGenerator.java
+++ b/guava-testlib/src/com/google/common/collect/testing/ReserializingTestSetGenerator.java
@@ -35,7 +35,7 @@ public class ReserializingTestSetGenerator<E> extends ReserializingTestCollectio
   }
 
   public static <E> TestSetGenerator<E> newInstance(TestSetGenerator<E> delegate) {
-    return new ReserializingTestSetGenerator<E>(delegate);
+    return new ReserializingTestSetGenerator<>(delegate);
   }
 
   @Override
diff --git a/guava-testlib/src/com/google/common/collect/testing/SafeTreeSet.java b/guava-testlib/src/com/google/common/collect/testing/SafeTreeSet.java
index 8ed48107347c..91d9fd9f750d 100644
--- a/guava-testlib/src/com/google/common/collect/testing/SafeTreeSet.java
+++ b/guava-testlib/src/com/google/common/collect/testing/SafeTreeSet.java
@@ -117,7 +117,7 @@ public Iterator<E> descendingIterator() {
 
   @Override
   public NavigableSet<E> descendingSet() {
-    return new SafeTreeSet<E>(delegate.descendingSet());
+    return new SafeTreeSet<>(delegate.descendingSet());
   }
 
   @Override
@@ -137,7 +137,7 @@ public SortedSet<E> headSet(E toElement) {
 
   @Override
   public NavigableSet<E> headSet(E toElement, boolean inclusive) {
-    return new SafeTreeSet<E>(delegate.headSet(checkValid(toElement), inclusive));
+    return new SafeTreeSet<>(delegate.headSet(checkValid(toElement), inclusive));
   }
 
   @Override
@@ -198,7 +198,7 @@ public int size() {
   @Override
   public NavigableSet<E> subSet(
       E fromElement, boolean fromInclusive, E toElement, boolean toInclusive) {
-    return new SafeTreeSet<E>(
+    return new SafeTreeSet<>(
         delegate.subSet(
             checkValid(fromElement), fromInclusive, checkValid(toElement), toInclusive));
   }
@@ -215,7 +215,7 @@ public SortedSet<E> tailSet(E fromElement) {
 
   @Override
   public NavigableSet<E> tailSet(E fromElement, boolean inclusive) {
-    return new SafeTreeSet<E>(delegate.tailSet(checkValid(fromElement), inclusive));
+    return new SafeTreeSet<>(delegate.tailSet(checkValid(fromElement), inclusive));
   }
 
   @Override
diff --git a/guava-testlib/src/com/google/common/collect/testing/SetTestSuiteBuilder.java b/guava-testlib/src/com/google/common/collect/testing/SetTestSuiteBuilder.java
index 26a2870ca9d5..4ac51a4612f1 100644
--- a/guava-testlib/src/com/google/common/collect/testing/SetTestSuiteBuilder.java
+++ b/guava-testlib/src/com/google/common/collect/testing/SetTestSuiteBuilder.java
@@ -78,6 +78,8 @@ protected List<TestSuite> createDerivedSuites(
               .named(getName() + " reserialized")
               .withFeatures(computeReserializedCollectionFeatures(parentBuilder.getFeatures()))
               .suppressing(parentBuilder.getSuppressedTests())
+              .withSetUp(parentBuilder.getSetUp())
+              .withTearDown(parentBuilder.getTearDown())
               .createTestSuite());
     }
     return derivedSuites;
diff --git a/guava-testlib/src/com/google/common/collect/testing/SortedMapInterfaceTest.java b/guava-testlib/src/com/google/common/collect/testing/SortedMapInterfaceTest.java
index 829c4cc27874..03266ab4776d 100644
--- a/guava-testlib/src/com/google/common/collect/testing/SortedMapInterfaceTest.java
+++ b/guava-testlib/src/com/google/common/collect/testing/SortedMapInterfaceTest.java
@@ -56,7 +56,7 @@ protected SortedMap<K, V> makeEitherMap() {
   }
 
   public void testTailMapWriteThrough() {
-    final SortedMap<K, V> map;
+    SortedMap<K, V> map;
     try {
       map = makePopulatedMap();
     } catch (UnsupportedOperationException e) {
@@ -82,7 +82,7 @@ public void testTailMapWriteThrough() {
   }
 
   public void testTailMapRemoveThrough() {
-    final SortedMap<K, V> map;
+    SortedMap<K, V> map;
     try {
       map = makePopulatedMap();
     } catch (UnsupportedOperationException e) {
@@ -105,7 +105,7 @@ public void testTailMapRemoveThrough() {
   }
 
   public void testTailMapClearThrough() {
-    final SortedMap<K, V> map;
+    SortedMap<K, V> map;
     try {
       map = makePopulatedMap();
     } catch (UnsupportedOperationException e) {
diff --git a/guava-testlib/src/com/google/common/collect/testing/SortedMapTestSuiteBuilder.java b/guava-testlib/src/com/google/common/collect/testing/SortedMapTestSuiteBuilder.java
index e95383af64a6..7944aaa6a0b8 100644
--- a/guava-testlib/src/com/google/common/collect/testing/SortedMapTestSuiteBuilder.java
+++ b/guava-testlib/src/com/google/common/collect/testing/SortedMapTestSuiteBuilder.java
@@ -105,12 +105,12 @@ public Set<Feature<? super Void>> getImpliedFeatures() {
    * these extreme values rather than relying on their regular sort ordering.
    */
   final TestSuite createSubmapSuite(
-      final FeatureSpecificTestSuiteBuilder<
+      FeatureSpecificTestSuiteBuilder<
               ?, ? extends OneSizeTestContainerGenerator<Map<K, V>, Entry<K, V>>>
           parentBuilder,
-      final Bound from,
-      final Bound to) {
-    final TestSortedMapGenerator<K, V> delegate =
+      Bound from,
+      Bound to) {
+    TestSortedMapGenerator<K, V> delegate =
         (TestSortedMapGenerator<K, V>) parentBuilder.getSubjectGenerator().getInnerGenerator();
 
     List<Feature<?>> features = new ArrayList<>();
@@ -121,6 +121,8 @@ final TestSuite createSubmapSuite(
         .named(parentBuilder.getName() + " subMap " + from + "-" + to)
         .withFeatures(features)
         .suppressing(parentBuilder.getSuppressedTests())
+        .withSetUp(parentBuilder.getSetUp())
+        .withTearDown(parentBuilder.getTearDown())
         .createTestSuite();
   }
 
diff --git a/guava-testlib/src/com/google/common/collect/testing/SortedSetTestSuiteBuilder.java b/guava-testlib/src/com/google/common/collect/testing/SortedSetTestSuiteBuilder.java
index e97b08fc5537..2835769e33f7 100644
--- a/guava-testlib/src/com/google/common/collect/testing/SortedSetTestSuiteBuilder.java
+++ b/guava-testlib/src/com/google/common/collect/testing/SortedSetTestSuiteBuilder.java
@@ -34,7 +34,7 @@
 @GwtIncompatible
 public class SortedSetTestSuiteBuilder<E> extends SetTestSuiteBuilder<E> {
   public static <E> SortedSetTestSuiteBuilder<E> using(TestSortedSetGenerator<E> generator) {
-    SortedSetTestSuiteBuilder<E> builder = new SortedSetTestSuiteBuilder<E>();
+    SortedSetTestSuiteBuilder<E> builder = new SortedSetTestSuiteBuilder<>();
     builder.usingGenerator(generator);
     return builder;
   }
@@ -78,12 +78,11 @@ protected List<TestSuite> createDerivedSuites(
    * these extreme values rather than relying on their regular sort ordering.
    */
   final TestSuite createSubsetSuite(
-      final FeatureSpecificTestSuiteBuilder<
-              ?, ? extends OneSizeTestContainerGenerator<Collection<E>, E>>
+      FeatureSpecificTestSuiteBuilder<?, ? extends OneSizeTestContainerGenerator<Collection<E>, E>>
           parentBuilder,
-      final Bound from,
-      final Bound to) {
-    final TestSortedSetGenerator<E> delegate =
+      Bound from,
+      Bound to) {
+    TestSortedSetGenerator<E> delegate =
         (TestSortedSetGenerator<E>) parentBuilder.getSubjectGenerator().getInnerGenerator();
 
     List<Feature<?>> features = new ArrayList<>(parentBuilder.getFeatures());
@@ -94,6 +93,8 @@ final TestSuite createSubsetSuite(
         .named(parentBuilder.getName() + " subSet " + from + "-" + to)
         .withFeatures(features)
         .suppressing(parentBuilder.getSuppressedTests())
+        .withSetUp(parentBuilder.getSetUp())
+        .withTearDown(parentBuilder.getTearDown())
         .createTestSuite();
   }
 
diff --git a/guava-testlib/src/com/google/common/collect/testing/SpliteratorTester.java b/guava-testlib/src/com/google/common/collect/testing/SpliteratorTester.java
index 08c771e7af25..9fad6e398dd1 100644
--- a/guava-testlib/src/com/google/common/collect/testing/SpliteratorTester.java
+++ b/guava-testlib/src/com/google/common/collect/testing/SpliteratorTester.java
@@ -20,6 +20,7 @@
 import static com.google.common.collect.testing.Helpers.assertEqualIgnoringOrder;
 import static com.google.common.collect.testing.Helpers.assertEqualInOrder;
 import static com.google.common.collect.testing.Platform.format;
+import static java.util.Comparator.naturalOrder;
 import static junit.framework.Assert.assertEquals;
 import static junit.framework.Assert.assertFalse;
 import static junit.framework.Assert.assertTrue;
@@ -296,7 +297,7 @@ public final Ordered expect(Iterable<?> elements) {
         if ((characteristics & Spliterator.SORTED) != 0) {
           Comparator<? super E> comparator = spliterator.getComparator();
           if (comparator == null) {
-            comparator = (Comparator) Comparator.naturalOrder();
+            comparator = (Comparator) naturalOrder();
           }
           assertTrue(Ordering.from(comparator).isOrdered(resultsForStrategy));
         }
diff --git a/guava-testlib/src/com/google/common/collect/testing/features/FeatureUtil.java b/guava-testlib/src/com/google/common/collect/testing/features/FeatureUtil.java
index 95cbc0b3d8be..2d11a0863494 100644
--- a/guava-testlib/src/com/google/common/collect/testing/features/FeatureUtil.java
+++ b/guava-testlib/src/com/google/common/collect/testing/features/FeatureUtil.java
@@ -139,12 +139,12 @@ public static TesterRequirements getTesterRequirements(Method testerMethod)
    */
   static TesterRequirements buildTesterRequirements(Class<?> testerClass)
       throws ConflictingRequirementsException {
-    final TesterRequirements declaredRequirements = buildDeclaredTesterRequirements(testerClass);
+    TesterRequirements declaredRequirements = buildDeclaredTesterRequirements(testerClass);
     Class<?> baseClass = testerClass.getSuperclass();
     if (baseClass == null) {
       return declaredRequirements;
     } else {
-      final TesterRequirements clonedBaseRequirements =
+      TesterRequirements clonedBaseRequirements =
           new TesterRequirements(getTesterRequirements(baseClass));
       return incorporateRequirements(clonedBaseRequirements, declaredRequirements, testerClass);
     }
@@ -176,8 +176,8 @@ static TesterRequirements buildTesterRequirements(Method testerMethod)
   private static TesterRequirements buildTesterRequirements(Annotation testerAnnotation)
       throws ConflictingRequirementsException {
     Class<? extends Annotation> annotationClass = testerAnnotation.annotationType();
-    final Feature<?>[] presentFeatures;
-    final Feature<?>[] absentFeatures;
+    Feature<?>[] presentFeatures;
+    Feature<?>[] absentFeatures;
     try {
       presentFeatures = (Feature[]) annotationClass.getMethod("value").invoke(testerAnnotation);
       absentFeatures = (Feature[]) annotationClass.getMethod("absent").invoke(testerAnnotation);
diff --git a/guava-testlib/src/com/google/common/collect/testing/google/AbstractMultimapTester.java b/guava-testlib/src/com/google/common/collect/testing/google/AbstractMultimapTester.java
index 7b7801db2633..7f649e757165 100644
--- a/guava-testlib/src/com/google/common/collect/testing/google/AbstractMultimapTester.java
+++ b/guava-testlib/src/com/google/common/collect/testing/google/AbstractMultimapTester.java
@@ -48,8 +48,8 @@ protected M multimap() {
   /** @return an array of the proper size with {@code null} as the key of the middle element. */
   protected Entry<K, V>[] createArrayWithNullKey() {
     Entry<K, V>[] array = createSamplesArray();
-    final int nullKeyLocation = getNullLocation();
-    final Entry<K, V> oldEntry = array[nullKeyLocation];
+    int nullKeyLocation = getNullLocation();
+    Entry<K, V> oldEntry = array[nullKeyLocation];
     array[nullKeyLocation] = Helpers.mapEntry(null, oldEntry.getValue());
     return array;
   }
@@ -57,8 +57,8 @@ protected Entry<K, V>[] createArrayWithNullKey() {
   /** @return an array of the proper size with {@code null} as the value of the middle element. */
   protected Entry<K, V>[] createArrayWithNullValue() {
     Entry<K, V>[] array = createSamplesArray();
-    final int nullValueLocation = getNullLocation();
-    final Entry<K, V> oldEntry = array[nullValueLocation];
+    int nullValueLocation = getNullLocation();
+    Entry<K, V> oldEntry = array[nullValueLocation];
     array[nullValueLocation] = Helpers.mapEntry(oldEntry.getKey(), null);
     return array;
   }
@@ -69,7 +69,7 @@ protected Entry<K, V>[] createArrayWithNullValue() {
    */
   protected Entry<K, V>[] createArrayWithNullKeyAndValue() {
     Entry<K, V>[] array = createSamplesArray();
-    final int nullValueLocation = getNullLocation();
+    int nullValueLocation = getNullLocation();
     array[nullValueLocation] = Helpers.mapEntry(null, null);
     return array;
   }
diff --git a/guava-testlib/src/com/google/common/collect/testing/google/BiMapTestSuiteBuilder.java b/guava-testlib/src/com/google/common/collect/testing/google/BiMapTestSuiteBuilder.java
index fa21a71a536d..0821fb0b554e 100644
--- a/guava-testlib/src/com/google/common/collect/testing/google/BiMapTestSuiteBuilder.java
+++ b/guava-testlib/src/com/google/common/collect/testing/google/BiMapTestSuiteBuilder.java
@@ -88,6 +88,8 @@ protected List<TestSuite> createDerivedSuites(
             .suppressing(parentBuilder.getSuppressedTests())
             .suppressing(SetCreationTester.class.getMethods())
             // BiMap.entrySet() duplicate-handling behavior is too confusing for SetCreationTester
+            .withSetUp(parentBuilder.getSetUp())
+            .withTearDown(parentBuilder.getTearDown())
             .createTestSuite());
     /*
      * TODO(cpovirk): the Map tests duplicate most of this effort by using a
@@ -101,6 +103,8 @@ protected List<TestSuite> createDerivedSuites(
             .suppressing(parentBuilder.getSuppressedTests())
             .suppressing(SetCreationTester.class.getMethods())
             // BiMap.values() duplicate-handling behavior is too confusing for SetCreationTester
+            .withSetUp(parentBuilder.getSetUp())
+            .withTearDown(parentBuilder.getTearDown())
             .createTestSuite());
     if (!parentBuilder.getFeatures().contains(NoRecurse.INVERSE)) {
       derived.add(
@@ -109,6 +113,8 @@ protected List<TestSuite> createDerivedSuites(
               .withFeatures(computeInverseFeatures(parentBuilder.getFeatures()))
               .named(parentBuilder.getName() + " inverse")
               .suppressing(parentBuilder.getSuppressedTests())
+              .withSetUp(parentBuilder.getSetUp())
+              .withTearDown(parentBuilder.getTearDown())
               .createTestSuite());
     }
 
diff --git a/guava-testlib/src/com/google/common/collect/testing/google/DerivedGoogleCollectionGenerators.java b/guava-testlib/src/com/google/common/collect/testing/google/DerivedGoogleCollectionGenerators.java
index bbeefd278e00..35579a01d758 100644
--- a/guava-testlib/src/com/google/common/collect/testing/google/DerivedGoogleCollectionGenerators.java
+++ b/guava-testlib/src/com/google/common/collect/testing/google/DerivedGoogleCollectionGenerators.java
@@ -159,9 +159,9 @@ public static class BiMapValueSetGenerator<K, V>
     public BiMapValueSetGenerator(
         OneSizeTestContainerGenerator<BiMap<K, V>, Entry<K, V>> mapGenerator) {
       this.mapGenerator = mapGenerator;
-      final SampleElements<Entry<K, V>> mapSamples = this.mapGenerator.samples();
+      SampleElements<Entry<K, V>> mapSamples = this.mapGenerator.samples();
       this.samples =
-          new SampleElements<V>(
+          new SampleElements<>(
               mapSamples.e0().getValue(),
               mapSamples.e1().getValue(),
               mapSamples.e2().getValue(),
@@ -194,7 +194,7 @@ public Set<V> create(Object... elements) {
 
     @Override
     public V[] createArray(int length) {
-      final V[] vs =
+      V[] vs =
           ((TestBiMapGenerator<K, V>) mapGenerator.getInnerGenerator()).createValueArray(length);
       return vs;
     }
diff --git a/guava-testlib/src/com/google/common/collect/testing/google/MapGenerators.java b/guava-testlib/src/com/google/common/collect/testing/google/MapGenerators.java
index bb84ea15f931..35063e815d0b 100644
--- a/guava-testlib/src/com/google/common/collect/testing/google/MapGenerators.java
+++ b/guava-testlib/src/com/google/common/collect/testing/google/MapGenerators.java
@@ -54,7 +54,7 @@ protected Map<String, String> create(Entry<String, String>[] entries) {
       for (Entry<String, String> entry : entries) {
         builder.put(entry.getKey(), entry.getValue());
       }
-      return builder.build();
+      return builder.buildOrThrow();
     }
   }
 
@@ -86,7 +86,7 @@ public Collection<UnhashableObject> create(UnhashableObject[] elements) {
       for (UnhashableObject value : elements) {
         builder.put(key++, value);
       }
-      return builder.build().values();
+      return builder.buildOrThrow().values();
     }
   }
 
@@ -97,7 +97,7 @@ public List<String> create(String[] elements) {
       for (int i = 0; i < elements.length; i++) {
         builder.put(elements[i], i);
       }
-      return builder.build().keySet().asList();
+      return builder.buildOrThrow().keySet().asList();
     }
   }
 
@@ -108,7 +108,7 @@ public List<String> create(String[] elements) {
       for (int i = 0; i < elements.length; i++) {
         builder.put(i, elements[i]);
       }
-      return builder.build().values().asList();
+      return builder.buildOrThrow().values().asList();
     }
   }
 
@@ -144,7 +144,7 @@ public List<Entry<String, Integer>> create(Object... elements) {
         Entry<String, Integer> entry = (Entry<String, Integer>) o;
         builder.put(entry);
       }
-      return builder.build().entrySet().asList();
+      return builder.buildOrThrow().entrySet().asList();
     }
   }
 
@@ -210,7 +210,7 @@ public Map<String, Collection<Integer>> create(Object... elements) {
         Integer value = Iterables.getOnlyElement(entry.getValue());
         builder.put(entry.getKey(), value);
       }
-      return builder.build().asMultimap().asMap();
+      return builder.buildOrThrow().asMultimap().asMap();
     }
 
     @Override
diff --git a/guava-testlib/src/com/google/common/collect/testing/google/MultimapTestSuiteBuilder.java b/guava-testlib/src/com/google/common/collect/testing/google/MultimapTestSuiteBuilder.java
index 6e5d5ed10a00..af9d261c3262 100644
--- a/guava-testlib/src/com/google/common/collect/testing/google/MultimapTestSuiteBuilder.java
+++ b/guava-testlib/src/com/google/common/collect/testing/google/MultimapTestSuiteBuilder.java
@@ -116,6 +116,8 @@ protected List<TestSuite> createDerivedSuites(
               .withFeatures(computeReserializedMultimapFeatures(parentBuilder.getFeatures()))
               .named(parentBuilder.getName() + " reserialized")
               .suppressing(parentBuilder.getSuppressedTests())
+              .withSetUp(parentBuilder.getSetUp())
+              .withTearDown(parentBuilder.getTearDown())
               .createTestSuite());
     }
 
@@ -124,6 +126,8 @@ protected List<TestSuite> createDerivedSuites(
             .withFeatures(computeAsMapFeatures(parentBuilder.getFeatures()))
             .named(parentBuilder.getName() + ".asMap")
             .suppressing(parentBuilder.getSuppressedTests())
+            .withSetUp(parentBuilder.getSetUp())
+            .withTearDown(parentBuilder.getTearDown())
             .createTestSuite());
 
     derivedSuites.add(computeEntriesTestSuite(parentBuilder));
@@ -154,6 +158,8 @@ TestSuite computeEntriesTestSuite(
         .withFeatures(computeEntriesFeatures(parentBuilder.getFeatures()))
         .named(parentBuilder.getName() + ".entries")
         .suppressing(parentBuilder.getSuppressedTests())
+        .withSetUp(parentBuilder.getSetUp())
+        .withTearDown(parentBuilder.getTearDown())
         .createTestSuite();
   }
 
@@ -165,6 +171,8 @@ TestSuite computeMultimapGetTestSuite(
         .withFeatures(computeMultimapGetFeatures(parentBuilder.getFeatures()))
         .named(parentBuilder.getName() + ".get[key]")
         .suppressing(parentBuilder.getSuppressedTests())
+        .withSetUp(parentBuilder.getSetUp())
+        .withTearDown(parentBuilder.getTearDown())
         .createTestSuite();
   }
 
@@ -180,6 +188,8 @@ TestSuite computeMultimapAsMapGetTestSuite(
           .withFeatures(features)
           .named(parentBuilder.getName() + ".asMap[].get[key]")
           .suppressing(parentBuilder.getSuppressedTests())
+          .withSetUp(parentBuilder.getSetUp())
+          .withTearDown(parentBuilder.getTearDown())
           .createTestSuite();
     }
   }
@@ -192,6 +202,8 @@ TestSuite computeKeysTestSuite(
         .withFeatures(computeKeysFeatures(parentBuilder.getFeatures()))
         .named(parentBuilder.getName() + ".keys")
         .suppressing(parentBuilder.getSuppressedTests())
+        .withSetUp(parentBuilder.getSetUp())
+        .withTearDown(parentBuilder.getTearDown())
         .createTestSuite();
   }
 
diff --git a/guava-testlib/src/com/google/common/collect/testing/google/MultisetNavigationTester.java b/guava-testlib/src/com/google/common/collect/testing/google/MultisetNavigationTester.java
index b65cd967ac0d..ce8e283a9c3e 100644
--- a/guava-testlib/src/com/google/common/collect/testing/google/MultisetNavigationTester.java
+++ b/guava-testlib/src/com/google/common/collect/testing/google/MultisetNavigationTester.java
@@ -82,7 +82,7 @@ public void setUp() throws Exception {
   @SuppressWarnings("unchecked")
   // Needed to stop Eclipse whining
   private void resetWithHole() {
-    List<E> container = new ArrayList<E>();
+    List<E> container = new ArrayList<>();
     container.addAll(Collections.nCopies(a.getCount(), a.getElement()));
     container.addAll(Collections.nCopies(c.getCount(), c.getElement()));
     super.resetContainer(getSubjectGenerator().create(container.toArray()));
diff --git a/guava-testlib/src/com/google/common/collect/testing/google/MultisetTestSuiteBuilder.java b/guava-testlib/src/com/google/common/collect/testing/google/MultisetTestSuiteBuilder.java
index 9e3d750f34ce..91d7a60e70f0 100644
--- a/guava-testlib/src/com/google/common/collect/testing/google/MultisetTestSuiteBuilder.java
+++ b/guava-testlib/src/com/google/common/collect/testing/google/MultisetTestSuiteBuilder.java
@@ -131,6 +131,8 @@ protected List<TestSuite> createDerivedSuites(
               .named(getName() + ".entrySet")
               .withFeatures(computeEntrySetFeatures(parentBuilder.getFeatures()))
               .suppressing(parentBuilder.getSuppressedTests())
+              .withSetUp(parentBuilder.getSetUp())
+              .withTearDown(parentBuilder.getTearDown())
               .createTestSuite());
     }
 
@@ -141,6 +143,8 @@ protected List<TestSuite> createDerivedSuites(
               .named(getName() + " reserialized")
               .withFeatures(computeReserializedMultisetFeatures(parentBuilder.getFeatures()))
               .suppressing(parentBuilder.getSuppressedTests())
+              .withSetUp(parentBuilder.getSetUp())
+              .withTearDown(parentBuilder.getTearDown())
               .createTestSuite());
     }
     return derivedSuites;
@@ -154,6 +158,8 @@ TestSuite createElementSetTestSuite(
         .named(getName() + ".elementSet")
         .withFeatures(computeElementSetFeatures(parentBuilder.getFeatures()))
         .suppressing(parentBuilder.getSuppressedTests())
+        .withSetUp(parentBuilder.getSetUp())
+        .withTearDown(parentBuilder.getTearDown())
         .createTestSuite();
   }
 
diff --git a/guava-testlib/src/com/google/common/collect/testing/google/SetMultimapAsMapTester.java b/guava-testlib/src/com/google/common/collect/testing/google/SetMultimapAsMapTester.java
index 49187dd1dffe..6e7995720846 100644
--- a/guava-testlib/src/com/google/common/collect/testing/google/SetMultimapAsMapTester.java
+++ b/guava-testlib/src/com/google/common/collect/testing/google/SetMultimapAsMapTester.java
@@ -58,7 +58,7 @@ public void testAsMapGetImplementsSet() {
 
   @MapFeature.Require(SUPPORTS_REMOVE)
   public void testAsMapRemoveImplementsSet() {
-    List<K> keys = new ArrayList<K>(multimap().keySet());
+    List<K> keys = new ArrayList<>(multimap().keySet());
     for (K key : keys) {
       resetCollection();
       assertTrue(multimap().asMap().remove(key) instanceof Set);
diff --git a/guava-testlib/src/com/google/common/collect/testing/google/SortedMultisetTestSuiteBuilder.java b/guava-testlib/src/com/google/common/collect/testing/google/SortedMultisetTestSuiteBuilder.java
index dafd52187df4..b44494b81ddf 100644
--- a/guava-testlib/src/com/google/common/collect/testing/google/SortedMultisetTestSuiteBuilder.java
+++ b/guava-testlib/src/com/google/common/collect/testing/google/SortedMultisetTestSuiteBuilder.java
@@ -56,7 +56,7 @@
 @GwtIncompatible
 public class SortedMultisetTestSuiteBuilder<E> extends MultisetTestSuiteBuilder<E> {
   public static <E> SortedMultisetTestSuiteBuilder<E> using(TestMultisetGenerator<E> generator) {
-    SortedMultisetTestSuiteBuilder<E> result = new SortedMultisetTestSuiteBuilder<E>();
+    SortedMultisetTestSuiteBuilder<E> result = new SortedMultisetTestSuiteBuilder<>();
     result.usingGenerator(generator);
     return result;
   }
@@ -138,8 +138,8 @@ List<TestSuite> createDerivedSuites(SortedMultisetTestSuiteBuilder<E> parentBuil
   }
 
   private TestSuite createSubMultisetSuite(
-      SortedMultisetTestSuiteBuilder<E> parentBuilder, final Bound from, final Bound to) {
-    final TestMultisetGenerator<E> delegate =
+      SortedMultisetTestSuiteBuilder<E> parentBuilder, Bound from, Bound to) {
+    TestMultisetGenerator<E> delegate =
         (TestMultisetGenerator<E>) parentBuilder.getSubjectGenerator();
 
     Set<Feature<?>> features = new HashSet<>();
@@ -152,15 +152,15 @@ private TestSuite createSubMultisetSuite(
     }
 
     SortedMultiset<E> emptyMultiset = (SortedMultiset<E>) delegate.create();
-    final Comparator<? super E> comparator = emptyMultiset.comparator();
+    Comparator<? super E> comparator = emptyMultiset.comparator();
     SampleElements<E> samples = delegate.samples();
     @SuppressWarnings("unchecked")
     List<E> samplesList =
         Arrays.asList(samples.e0(), samples.e1(), samples.e2(), samples.e3(), samples.e4());
 
     Collections.sort(samplesList, comparator);
-    final E firstInclusive = samplesList.get(0);
-    final E lastInclusive = samplesList.get(samplesList.size() - 1);
+    E firstInclusive = samplesList.get(0);
+    E lastInclusive = samplesList.get(samplesList.size() - 1);
 
     return SortedMultisetTestSuiteBuilder.using(
             new ForwardingTestMultisetGenerator<E>(delegate) {
@@ -187,7 +187,7 @@ public SortedMultiset<E> create(Object... entries) {
                 }
 
                 // the regular values should be visible after filtering
-                List<E> allEntries = new ArrayList<E>();
+                List<E> allEntries = new ArrayList<>();
                 allEntries.addAll(extremeValues);
                 allEntries.addAll(normalValues);
                 SortedMultiset<E> multiset =
@@ -234,7 +234,7 @@ private List<String> getExtremeValues() {
   }
 
   private TestSuite createDescendingSuite(SortedMultisetTestSuiteBuilder<E> parentBuilder) {
-    final TestMultisetGenerator<E> delegate =
+    TestMultisetGenerator<E> delegate =
         (TestMultisetGenerator<E>) parentBuilder.getSubjectGenerator();
 
     Set<Feature<?>> features = new HashSet<>();
@@ -263,7 +263,7 @@ public Iterable<E> order(List<E> insertionOrder) {
   }
 
   private TestSuite createReserializedSuite(SortedMultisetTestSuiteBuilder<E> parentBuilder) {
-    final TestMultisetGenerator<E> delegate =
+    TestMultisetGenerator<E> delegate =
         (TestMultisetGenerator<E>) parentBuilder.getSubjectGenerator();
 
     Set<Feature<?>> features = new HashSet<>(parentBuilder.getFeatures());
diff --git a/guava-testlib/src/com/google/common/collect/testing/google/SortedSetMultimapAsMapTester.java b/guava-testlib/src/com/google/common/collect/testing/google/SortedSetMultimapAsMapTester.java
index 1c00f0970102..e95b74f84b0c 100644
--- a/guava-testlib/src/com/google/common/collect/testing/google/SortedSetMultimapAsMapTester.java
+++ b/guava-testlib/src/com/google/common/collect/testing/google/SortedSetMultimapAsMapTester.java
@@ -52,7 +52,7 @@ public void testAsMapGetImplementsSortedSet() {
 
   @MapFeature.Require(SUPPORTS_REMOVE)
   public void testAsMapRemoveImplementsSortedSet() {
-    List<K> keys = new ArrayList<K>(multimap().keySet());
+    List<K> keys = new ArrayList<>(multimap().keySet());
     for (K key : keys) {
       resetCollection();
       SortedSet<V> valueSet = (SortedSet<V>) multimap().asMap().remove(key);
diff --git a/guava-testlib/src/com/google/common/collect/testing/google/UnmodifiableCollectionTests.java b/guava-testlib/src/com/google/common/collect/testing/google/UnmodifiableCollectionTests.java
index 005746f4be20..40b2c859d20c 100644
--- a/guava-testlib/src/com/google/common/collect/testing/google/UnmodifiableCollectionTests.java
+++ b/guava-testlib/src/com/google/common/collect/testing/google/UnmodifiableCollectionTests.java
@@ -201,7 +201,7 @@ public static <E> void assertSetIsUnmodifiable(Set<E> set, E sampleElement) {
    * @param sampleElement an element of the same type as that contained by {@code multiset}. {@code
    *     multiset} may or may not have {@code sampleElement} as a member.
    */
-  public static <E> void assertMultisetIsUnmodifiable(Multiset<E> multiset, final E sampleElement) {
+  public static <E> void assertMultisetIsUnmodifiable(Multiset<E> multiset, E sampleElement) {
     Multiset<E> copy = LinkedHashMultiset.create(multiset);
     assertCollectionsAreEquivalent(multiset, copy);
 
@@ -264,7 +264,7 @@ public E getElement() {
    *     multimap} may or may not have {@code sampleValue} as a key.
    */
   public static <K, V> void assertMultimapIsUnmodifiable(
-      Multimap<K, V> multimap, final K sampleKey, final V sampleValue) {
+      Multimap<K, V> multimap, K sampleKey, V sampleValue) {
     List<Entry<K, V>> originalEntries =
         Collections.unmodifiableList(Lists.newArrayList(multimap.entries()));
 
diff --git a/guava-testlib/src/com/google/common/collect/testing/testers/CollectionForEachTester.java b/guava-testlib/src/com/google/common/collect/testing/testers/CollectionForEachTester.java
index d1a36af873fc..af8490d31e78 100644
--- a/guava-testlib/src/com/google/common/collect/testing/testers/CollectionForEachTester.java
+++ b/guava-testlib/src/com/google/common/collect/testing/testers/CollectionForEachTester.java
@@ -38,14 +38,14 @@
 public class CollectionForEachTester<E> extends AbstractCollectionTester<E> {
   @CollectionFeature.Require(absent = KNOWN_ORDER)
   public void testForEachUnknownOrder() {
-    List<E> elements = new ArrayList<E>();
+    List<E> elements = new ArrayList<>();
     collection.forEach(elements::add);
     Helpers.assertEqualIgnoringOrder(Arrays.asList(createSamplesArray()), elements);
   }
 
   @CollectionFeature.Require(KNOWN_ORDER)
   public void testForEachKnownOrder() {
-    List<E> elements = new ArrayList<E>();
+    List<E> elements = new ArrayList<>();
     collection.forEach(elements::add);
     List<E> expected = Helpers.copyToList(getOrderedElements());
     assertEquals("Different ordered iteration", expected, elements);
diff --git a/guava-testlib/src/com/google/common/collect/testing/testers/CollectionIteratorTester.java b/guava-testlib/src/com/google/common/collect/testing/testers/CollectionIteratorTester.java
index b17049709e81..1699fe19dced 100644
--- a/guava-testlib/src/com/google/common/collect/testing/testers/CollectionIteratorTester.java
+++ b/guava-testlib/src/com/google/common/collect/testing/testers/CollectionIteratorTester.java
@@ -51,7 +51,7 @@
 @Ignore // Affects only Android test runner, which respects JUnit 4 annotations on JUnit 3 tests.
 public class CollectionIteratorTester<E> extends AbstractCollectionTester<E> {
   public void testIterator() {
-    List<E> iteratorElements = new ArrayList<E>();
+    List<E> iteratorElements = new ArrayList<>();
     for (E element : collection) { // uses iterator()
       iteratorElements.add(element);
     }
@@ -60,7 +60,7 @@ public void testIterator() {
 
   @CollectionFeature.Require(KNOWN_ORDER)
   public void testIterationOrdering() {
-    List<E> iteratorElements = new ArrayList<E>();
+    List<E> iteratorElements = new ArrayList<>();
     for (E element : collection) { // uses iterator()
       iteratorElements.add(element);
     }
@@ -72,7 +72,7 @@ public void testIterationOrdering() {
   @CollectionSize.Require(absent = ZERO)
   public void testIterator_nullElement() {
     initCollectionWithNullElement();
-    List<E> iteratorElements = new ArrayList<E>();
+    List<E> iteratorElements = new ArrayList<>();
     for (E element : collection) { // uses iterator()
       iteratorElements.add(element);
     }
diff --git a/guava-testlib/src/com/google/common/collect/testing/testers/CollectionToArrayTester.java b/guava-testlib/src/com/google/common/collect/testing/testers/CollectionToArrayTester.java
index 83a4ceac869d..b40fc3636943 100644
--- a/guava-testlib/src/com/google/common/collect/testing/testers/CollectionToArrayTester.java
+++ b/guava-testlib/src/com/google/common/collect/testing/testers/CollectionToArrayTester.java
@@ -48,8 +48,8 @@ public void testToArray_noArgs() {
   }
 
   /**
-   * {@link Collection#toArray(Object[])} says: "Note that <tt>toArray(new Object[0])</tt> is
-   * identical in function to <tt>toArray()</tt>."
+   * {@link Collection#toArray(Object[])} says: "Note that {@code toArray(new Object[0])} is
+   * identical in function to {@code toArray()}."
    *
    * <p>For maximum effect, the collection under test should be created from an element array of a
    * type other than {@code Object[]}.
diff --git a/guava-testlib/src/com/google/common/collect/testing/testers/MapReplaceAllTester.java b/guava-testlib/src/com/google/common/collect/testing/testers/MapReplaceAllTester.java
index 4808f5427956..eb37a6013521 100644
--- a/guava-testlib/src/com/google/common/collect/testing/testers/MapReplaceAllTester.java
+++ b/guava-testlib/src/com/google/common/collect/testing/testers/MapReplaceAllTester.java
@@ -42,11 +42,11 @@
 @Ignore // Affects only Android test runner, which respects JUnit 4 annotations on JUnit 3 tests.
 public class MapReplaceAllTester<K, V> extends AbstractMapTester<K, V> {
   private SampleElements<K> keys() {
-    return new SampleElements<K>(k0(), k1(), k2(), k3(), k4());
+    return new SampleElements<>(k0(), k1(), k2(), k3(), k4());
   }
 
   private SampleElements<V> values() {
-    return new SampleElements<V>(v0(), v1(), v2(), v3(), v4());
+    return new SampleElements<>(v0(), v1(), v2(), v3(), v4());
   }
 
   @MapFeature.Require(SUPPORTS_PUT)
diff --git a/guava-testlib/src/com/google/common/collect/testing/testers/NavigableSetNavigationTester.java b/guava-testlib/src/com/google/common/collect/testing/testers/NavigableSetNavigationTester.java
index 39016169d986..8b056b4cb1a1 100644
--- a/guava-testlib/src/com/google/common/collect/testing/testers/NavigableSetNavigationTester.java
+++ b/guava-testlib/src/com/google/common/collect/testing/testers/NavigableSetNavigationTester.java
@@ -218,7 +218,7 @@ public void testPollLastUnsupported() {
 
   @CollectionSize.Require(SEVERAL)
   public void testDescendingNavigation() {
-    List<E> descending = new ArrayList<E>();
+    List<E> descending = new ArrayList<>();
     for (Iterator<E> i = navigableSet.descendingIterator(); i.hasNext(); ) {
       descending.add(i.next());
     }
diff --git a/guava-testlib/src/com/google/common/escape/testing/EscaperAsserts.java b/guava-testlib/src/com/google/common/escape/testing/EscaperAsserts.java
index 3920afe4c137..31ac2015dd04 100644
--- a/guava-testlib/src/com/google/common/escape/testing/EscaperAsserts.java
+++ b/guava-testlib/src/com/google/common/escape/testing/EscaperAsserts.java
@@ -18,7 +18,6 @@
 
 import static com.google.common.escape.Escapers.computeReplacement;
 
-import com.google.common.annotations.Beta;
 import com.google.common.annotations.GwtCompatible;
 import com.google.common.escape.CharEscaper;
 import com.google.common.escape.Escaper;
@@ -32,7 +31,6 @@
  * @author David Beaumont
  * @since 15.0
  */
-@Beta
 @GwtCompatible
 public final class EscaperAsserts {
   private EscaperAsserts() {}
diff --git a/guava-testlib/src/com/google/common/testing/AbstractPackageSanityTests.java b/guava-testlib/src/com/google/common/testing/AbstractPackageSanityTests.java
index 962b15f6d677..1e31bbfb408f 100644
--- a/guava-testlib/src/com/google/common/testing/AbstractPackageSanityTests.java
+++ b/guava-testlib/src/com/google/common/testing/AbstractPackageSanityTests.java
@@ -116,12 +116,7 @@ public abstract class AbstractPackageSanityTests extends TestCase {
    * @since 19.0
    */
   public static final Predicate<Class<?>> UNDERSCORE_IN_NAME =
-      new Predicate<Class<?>>() {
-        @Override
-        public boolean apply(Class<?> c) {
-          return c.getSimpleName().contains("_");
-        }
-      };
+      (Class<?> c) -> c.getSimpleName().contains("_");
 
   /* The names of the expected method that tests null checks. */
   private static final ImmutableList<String> NULL_TEST_METHOD_NAMES =
@@ -152,12 +147,7 @@ public boolean apply(Class<?> c) {
   private final ClassSanityTester tester = new ClassSanityTester();
   private Visibility visibility = Visibility.PACKAGE;
   private Predicate<Class<?>> classFilter =
-      new Predicate<Class<?>>() {
-        @Override
-        public boolean apply(Class<?> cls) {
-          return visibility.isVisible(cls.getModifiers());
-        }
-      };
+      (Class<?> cls) -> visibility.isVisible(cls.getModifiers());
 
   /**
    * Restricts the sanity tests for public API only. By default, package-private API are also
@@ -415,8 +405,8 @@ private static boolean isEqualsDefined(Class<?> cls) {
 
   abstract static class Chopper {
 
-    final Chopper or(final Chopper you) {
-      final Chopper i = this;
+    final Chopper or(Chopper you) {
+      Chopper i = this;
       return new Chopper() {
         @Override
         Optional<String> chop(String str) {
@@ -427,7 +417,7 @@ Optional<String> chop(String str) {
 
     abstract Optional<String> chop(String str);
 
-    static Chopper suffix(final String suffix) {
+    static Chopper suffix(String suffix) {
       return new Chopper() {
         @Override
         Optional<String> chop(String str) {
diff --git a/guava-testlib/src/com/google/common/testing/ArbitraryInstances.java b/guava-testlib/src/com/google/common/testing/ArbitraryInstances.java
index f38c52e08aa2..1325d7f8c09e 100644
--- a/guava-testlib/src/com/google/common/testing/ArbitraryInstances.java
+++ b/guava-testlib/src/com/google/common/testing/ArbitraryInstances.java
@@ -18,7 +18,6 @@
 
 import static com.google.common.base.Preconditions.checkArgument;
 
-import com.google.common.annotations.Beta;
 import com.google.common.annotations.GwtIncompatible;
 import com.google.common.base.CharMatcher;
 import com.google.common.base.Charsets;
@@ -74,6 +73,7 @@
 import com.google.common.primitives.Primitives;
 import com.google.common.primitives.UnsignedInteger;
 import com.google.common.primitives.UnsignedLong;
+import com.google.errorprone.annotations.Keep;
 import java.io.ByteArrayInputStream;
 import java.io.ByteArrayOutputStream;
 import java.io.File;
@@ -171,7 +171,6 @@
  * @author Ben Yu
  * @since 12.0
  */
-@Beta
 @GwtIncompatible
 public final class ArbitraryInstances {
 
@@ -439,6 +438,7 @@ public InMemoryPrintWriter() {
     }
 
     public static final class DeterministicRandom extends Random {
+      @Keep
       public DeterministicRandom() {
         super(0);
       }
diff --git a/guava-testlib/src/com/google/common/testing/CollectorTester.java b/guava-testlib/src/com/google/common/testing/CollectorTester.java
index 9478a1fd20cf..ab6e544d8a24 100644
--- a/guava-testlib/src/com/google/common/testing/CollectorTester.java
+++ b/guava-testlib/src/com/google/common/testing/CollectorTester.java
@@ -19,7 +19,6 @@
 import static com.google.common.base.Preconditions.checkNotNull;
 import static junit.framework.Assert.assertTrue;
 
-import com.google.common.annotations.Beta;
 import com.google.common.annotations.GwtCompatible;
 import java.util.ArrayList;
 import java.util.Arrays;
@@ -46,7 +45,6 @@
  * @author Louis Wasserman
  * @since 21.0
  */
-@Beta
 @GwtCompatible
 public final class CollectorTester<T, A, R> {
   /**
diff --git a/guava-testlib/src/com/google/common/testing/EqualsTester.java b/guava-testlib/src/com/google/common/testing/EqualsTester.java
index 2c8e08b87c57..9c93c9a492a1 100644
--- a/guava-testlib/src/com/google/common/testing/EqualsTester.java
+++ b/guava-testlib/src/com/google/common/testing/EqualsTester.java
@@ -20,7 +20,6 @@
 import static junit.framework.Assert.assertEquals;
 import static junit.framework.Assert.assertTrue;
 
-import com.google.common.annotations.Beta;
 import com.google.common.annotations.GwtCompatible;
 import com.google.common.base.Equivalence;
 import com.google.common.collect.ImmutableList;
@@ -74,7 +73,6 @@
  * @author Jige Yu
  * @since 10.0
  */
-@Beta
 @GwtCompatible
 public final class EqualsTester {
   private static final int REPETITIONS = 3;
@@ -122,7 +120,7 @@ private void testItems() {
       assertTrue(
           item + " must not be Object#equals to an arbitrary object of another class",
           !item.equals(NotAnInstance.EQUAL_TO_NOTHING));
-      assertEquals(item + " must be Object#equals to itself", item, item);
+      assertTrue(item + " must be Object#equals to itself", item.equals(item));
       assertEquals(
           "the Object#hashCode of " + item + " must be consistent",
           item.hashCode(),
diff --git a/guava-testlib/src/com/google/common/testing/EquivalenceTester.java b/guava-testlib/src/com/google/common/testing/EquivalenceTester.java
index ce1dc98c440e..8de2625d0ed6 100644
--- a/guava-testlib/src/com/google/common/testing/EquivalenceTester.java
+++ b/guava-testlib/src/com/google/common/testing/EquivalenceTester.java
@@ -20,7 +20,6 @@
 import static junit.framework.Assert.assertEquals;
 import static junit.framework.Assert.assertTrue;
 
-import com.google.common.annotations.Beta;
 import com.google.common.annotations.GwtCompatible;
 import com.google.common.base.Equivalence;
 import com.google.common.collect.ImmutableList;
@@ -49,7 +48,6 @@
  * @author Gregory Kick
  * @since 10.0
  */
-@Beta
 @GwtCompatible
 public final class EquivalenceTester<T> {
   private static final int REPETITIONS = 3;
@@ -60,12 +58,11 @@ public final class EquivalenceTester<T> {
 
   private EquivalenceTester(Equivalence<? super T> equivalence) {
     this.equivalence = checkNotNull(equivalence);
-    this.delegate =
-        new RelationshipTester<T>(equivalence, "equivalent", "hash", new ItemReporter());
+    this.delegate = new RelationshipTester<>(equivalence, "equivalent", "hash", new ItemReporter());
   }
 
   public static <T> EquivalenceTester<T> of(Equivalence<? super T> equivalence) {
-    return new EquivalenceTester<T>(equivalence);
+    return new EquivalenceTester<>(equivalence);
   }
 
   /**
diff --git a/guava-testlib/src/com/google/common/testing/FakeTicker.java b/guava-testlib/src/com/google/common/testing/FakeTicker.java
index cc18e65019f8..d18e6bce77f9 100644
--- a/guava-testlib/src/com/google/common/testing/FakeTicker.java
+++ b/guava-testlib/src/com/google/common/testing/FakeTicker.java
@@ -18,7 +18,6 @@
 
 import static com.google.common.base.Preconditions.checkArgument;
 
-import com.google.common.annotations.Beta;
 import com.google.common.annotations.GwtCompatible;
 import com.google.common.annotations.GwtIncompatible;
 import com.google.common.base.Ticker;
@@ -36,7 +35,6 @@
  * @author Jige Yu
  * @since 10.0
  */
-@Beta
 @GwtCompatible
 public class FakeTicker extends Ticker {
 
diff --git a/guava-testlib/src/com/google/common/testing/ForwardingWrapperTester.java b/guava-testlib/src/com/google/common/testing/ForwardingWrapperTester.java
index 4ee461eb245f..605d3a055b28 100644
--- a/guava-testlib/src/com/google/common/testing/ForwardingWrapperTester.java
+++ b/guava-testlib/src/com/google/common/testing/ForwardingWrapperTester.java
@@ -22,7 +22,6 @@
 import static junit.framework.Assert.assertEquals;
 import static junit.framework.Assert.fail;
 
-import com.google.common.annotations.Beta;
 import com.google.common.annotations.GwtIncompatible;
 import com.google.common.base.Function;
 import com.google.common.base.Throwables;
@@ -53,7 +52,6 @@
  * @author Ben Yu
  * @since 14.0
  */
-@Beta
 @GwtIncompatible
 public final class ForwardingWrapperTester {
 
@@ -129,7 +127,7 @@ private static <T> void testSuccessfulForwarding(
 
   private static <T> void testExceptionPropagation(
       Class<T> interfaceType, Method method, Function<? super T, ? extends T> wrapperFunction) {
-    final RuntimeException exception = new RuntimeException();
+    RuntimeException exception = new RuntimeException();
     T proxy =
         Reflection.newProxy(
             interfaceType,
@@ -175,7 +173,7 @@ private static <T> void testToString(
 
   private static Object[] getParameterValues(Method method) {
     FreshValueGenerator paramValues = new FreshValueGenerator();
-    final List<Object> passedArgs = Lists.newArrayList();
+    List<Object> passedArgs = Lists.newArrayList();
     for (Class<?> paramType : method.getParameterTypes()) {
       passedArgs.add(paramValues.generateFresh(paramType));
     }
diff --git a/guava-testlib/src/com/google/common/testing/FreshValueGenerator.java b/guava-testlib/src/com/google/common/testing/FreshValueGenerator.java
index a2fe93a13bfe..bb51e408b285 100644
--- a/guava-testlib/src/com/google/common/testing/FreshValueGenerator.java
+++ b/guava-testlib/src/com/google/common/testing/FreshValueGenerator.java
@@ -141,7 +141,7 @@ class FreshValueGenerator {
         builder.put(method.getReturnType(), method);
       }
     }
-    GENERATORS = builder.build();
+    GENERATORS = builder.buildOrThrow();
   }
 
   private static final ImmutableMap<Class<?>, Method> EMPTY_GENERATORS;
@@ -153,7 +153,7 @@ class FreshValueGenerator {
         builder.put(method.getReturnType(), method);
       }
     }
-    EMPTY_GENERATORS = builder.build();
+    EMPTY_GENERATORS = builder.buildOrThrow();
   }
 
   private final AtomicInteger freshness = new AtomicInteger(1);
@@ -356,7 +356,7 @@ private static String paramString(Class<?> type, int i) {
   private @interface Empty {}
 
   @Generates
-  private Class<?> generateClass() {
+  Class<?> generateClass() {
     return pickInstance(
         ImmutableList.of(
             int.class, long.class, void.class, Object.class, Object[].class, Iterable.class),
@@ -364,147 +364,147 @@ private Class<?> generateClass() {
   }
 
   @Generates
-  private Object generateObject() {
+  Object generateObject() {
     return generateString();
   }
 
   @Generates
-  private Number generateNumber() {
+  Number generateNumber() {
     return generateInt();
   }
 
   @Generates
-  private int generateInt() {
+  int generateInt() {
     return freshness.get();
   }
 
   @Generates
-  private Integer generateInteger() {
+  Integer generateInteger() {
     return new Integer(generateInt());
   }
 
   @Generates
-  private long generateLong() {
+  long generateLong() {
     return generateInt();
   }
 
   @Generates
-  private Long generateLongObject() {
+  Long generateLongObject() {
     return new Long(generateLong());
   }
 
   @Generates
-  private float generateFloat() {
+  float generateFloat() {
     return generateInt();
   }
 
   @Generates
-  private Float generateFloatObject() {
+  Float generateFloatObject() {
     return new Float(generateFloat());
   }
 
   @Generates
-  private double generateDouble() {
+  double generateDouble() {
     return generateInt();
   }
 
   @Generates
-  private Double generateDoubleObject() {
+  Double generateDoubleObject() {
     return new Double(generateDouble());
   }
 
   @Generates
-  private short generateShort() {
+  short generateShort() {
     return (short) generateInt();
   }
 
   @Generates
-  private Short generateShortObject() {
+  Short generateShortObject() {
     return new Short(generateShort());
   }
 
   @Generates
-  private byte generateByte() {
+  byte generateByte() {
     return (byte) generateInt();
   }
 
   @Generates
-  private Byte generateByteObject() {
+  Byte generateByteObject() {
     return new Byte(generateByte());
   }
 
   @Generates
-  private char generateChar() {
+  char generateChar() {
     return generateString().charAt(0);
   }
 
   @Generates
-  private Character generateCharacter() {
+  Character generateCharacter() {
     return new Character(generateChar());
   }
 
   @Generates
-  private boolean generateBoolean() {
+  boolean generateBoolean() {
     return generateInt() % 2 == 0;
   }
 
   @Generates
-  private Boolean generateBooleanObject() {
+  Boolean generateBooleanObject() {
     return new Boolean(generateBoolean());
   }
 
   @Generates
-  private UnsignedInteger generateUnsignedInteger() {
+  UnsignedInteger generateUnsignedInteger() {
     return UnsignedInteger.fromIntBits(generateInt());
   }
 
   @Generates
-  private UnsignedLong generateUnsignedLong() {
+  UnsignedLong generateUnsignedLong() {
     return UnsignedLong.fromLongBits(generateLong());
   }
 
   @Generates
-  private BigInteger generateBigInteger() {
+  BigInteger generateBigInteger() {
     return BigInteger.valueOf(generateInt());
   }
 
   @Generates
-  private BigDecimal generateBigDecimal() {
+  BigDecimal generateBigDecimal() {
     return BigDecimal.valueOf(generateInt());
   }
 
   @Generates
-  private CharSequence generateCharSequence() {
+  CharSequence generateCharSequence() {
     return generateString();
   }
 
   @Generates
-  private String generateString() {
+  String generateString() {
     return Integer.toString(generateInt());
   }
 
   @Generates
-  private Comparable<?> generateComparable() {
+  Comparable<?> generateComparable() {
     return generateString();
   }
 
   @Generates
-  private Pattern generatePattern() {
+  Pattern generatePattern() {
     return Pattern.compile(generateString());
   }
 
   @Generates
-  private Charset generateCharset() {
+  Charset generateCharset() {
     return pickInstance(Charset.availableCharsets().values(), Charsets.UTF_8);
   }
 
   @Generates
-  private Locale generateLocale() {
+  Locale generateLocale() {
     return pickInstance(Locale.getAvailableLocales(), Locale.US);
   }
 
   @Generates
-  private Currency generateCurrency() {
+  Currency generateCurrency() {
     try {
       Method method = Currency.class.getMethod("getAvailableCurrencies");
       @SuppressWarnings("unchecked") // getAvailableCurrencies() returns Set<Currency>.
@@ -539,53 +539,53 @@ private Currency preJava7FreshCurrency() {
   }
 
   @Empty
-  private <T> Optional<T> generateJavaOptional() {
+  <T> Optional<T> generateJavaOptional() {
     return Optional.empty();
   }
 
   @Generates
-  private <T> Optional<T> generateJavaOptional(T value) {
+  <T> Optional<T> generateJavaOptional(T value) {
     return Optional.of(value);
   }
 
   @Generates
-  private OptionalInt generateOptionalInt() {
+  OptionalInt generateOptionalInt() {
     return OptionalInt.of(generateInt());
   }
 
   @Generates
-  private OptionalLong generateOptionalLong() {
+  OptionalLong generateOptionalLong() {
     return OptionalLong.of(generateLong());
   }
 
   @Generates
-  private OptionalDouble generateOptionalDouble() {
+  OptionalDouble generateOptionalDouble() {
     return OptionalDouble.of(generateDouble());
   }
 
   // common.base
   @Empty
-  private <T> com.google.common.base.Optional<T> generateGoogleOptional() {
+  <T> com.google.common.base.Optional<T> generateGoogleOptional() {
     return com.google.common.base.Optional.absent();
   }
 
   @Generates
-  private <T> com.google.common.base.Optional<T> generateGoogleOptional(T value) {
+  <T> com.google.common.base.Optional<T> generateGoogleOptional(T value) {
     return com.google.common.base.Optional.of(value);
   }
 
   @Generates
-  private Joiner generateJoiner() {
+  Joiner generateJoiner() {
     return Joiner.on(generateString());
   }
 
   @Generates
-  private Splitter generateSplitter() {
+  Splitter generateSplitter() {
     return Splitter.on(generateString());
   }
 
   @Generates
-  private <T> Equivalence<T> generateEquivalence() {
+  <T> Equivalence<T> generateEquivalence() {
     return new Equivalence<T>() {
       @Override
       protected boolean doEquivalent(T a, T b) {
@@ -607,7 +607,7 @@ public String toString() {
   }
 
   @Generates
-  private CharMatcher generateCharMatcher() {
+  CharMatcher generateCharMatcher() {
     return new CharMatcher() {
       @Override
       public boolean matches(char c) {
@@ -624,7 +624,7 @@ public String toString() {
   }
 
   @Generates
-  private Ticker generateTicker() {
+  Ticker generateTicker() {
     return new Ticker() {
       @Override
       public long read() {
@@ -642,12 +642,12 @@ public String toString() {
 
   // collect
   @Generates
-  private <T> Comparator<T> generateComparator() {
+  <T> Comparator<T> generateComparator() {
     return generateOrdering();
   }
 
   @Generates
-  private <T> Ordering<T> generateOrdering() {
+  <T> Ordering<T> generateOrdering() {
     return new Ordering<T>() {
       @Override
       public int compare(T left, T right) {
@@ -664,279 +664,280 @@ public String toString() {
   }
 
   @Empty
-  private static <C extends Comparable<?>> Range<C> generateRange() {
+  static <C extends Comparable<?>> Range<C> generateRange() {
     return Range.all();
   }
 
   @Generates
-  private static <C extends Comparable<?>> Range<C> generateRange(C freshElement) {
+  static <C extends Comparable<?>> Range<C> generateRange(C freshElement) {
     return Range.singleton(freshElement);
   }
 
   @Generates
-  private static <E> Iterable<E> generateIterable(E freshElement) {
+  static <E> Iterable<E> generateIterable(@Nullable E freshElement) {
     return generateList(freshElement);
   }
 
   @Generates
-  private static <E> Collection<E> generateCollection(E freshElement) {
+  static <E> Collection<E> generateCollection(@Nullable E freshElement) {
     return generateList(freshElement);
   }
 
   @Generates
-  private static <E> List<E> generateList(E freshElement) {
+  static <E> List<E> generateList(@Nullable E freshElement) {
     return generateArrayList(freshElement);
   }
 
   @Generates
-  private static <E> ArrayList<E> generateArrayList(E freshElement) {
+  static <E> ArrayList<E> generateArrayList(@Nullable E freshElement) {
     ArrayList<E> list = Lists.newArrayList();
     list.add(freshElement);
     return list;
   }
 
   @Generates
-  private static <E> LinkedList<E> generateLinkedList(E freshElement) {
+  static <E> LinkedList<E> generateLinkedList(@Nullable E freshElement) {
     LinkedList<E> list = Lists.newLinkedList();
     list.add(freshElement);
     return list;
   }
 
   @Generates
-  private static <E> ImmutableList<E> generateImmutableList(E freshElement) {
+  static <E> ImmutableList<E> generateImmutableList(E freshElement) {
     return ImmutableList.of(freshElement);
   }
 
   @Generates
-  private static <E> ImmutableCollection<E> generateImmutableCollection(E freshElement) {
+  static <E> ImmutableCollection<E> generateImmutableCollection(E freshElement) {
     return generateImmutableList(freshElement);
   }
 
   @Generates
-  private static <E> Set<E> generateSet(E freshElement) {
+  static <E> Set<E> generateSet(@Nullable E freshElement) {
     return generateHashSet(freshElement);
   }
 
   @Generates
-  private static <E> HashSet<E> generateHashSet(E freshElement) {
+  static <E> HashSet<E> generateHashSet(@Nullable E freshElement) {
     return generateLinkedHashSet(freshElement);
   }
 
   @Generates
-  private static <E> LinkedHashSet<E> generateLinkedHashSet(E freshElement) {
+  static <E> LinkedHashSet<E> generateLinkedHashSet(@Nullable E freshElement) {
     LinkedHashSet<E> set = Sets.newLinkedHashSet();
     set.add(freshElement);
     return set;
   }
 
   @Generates
-  private static <E> ImmutableSet<E> generateImmutableSet(E freshElement) {
+  static <E> ImmutableSet<E> generateImmutableSet(E freshElement) {
     return ImmutableSet.of(freshElement);
   }
 
   @Generates
-  private static <E extends Comparable<? super E>> SortedSet<E> generateSortedSet(E freshElement) {
+  static <E extends Comparable<? super E>> SortedSet<E> generateSortedSet(E freshElement) {
     return generateNavigableSet(freshElement);
   }
 
   @Generates
-  private static <E extends Comparable<? super E>> NavigableSet<E> generateNavigableSet(
-      E freshElement) {
+  static <E extends Comparable<? super E>> NavigableSet<E> generateNavigableSet(E freshElement) {
     return generateTreeSet(freshElement);
   }
 
   @Generates
-  private static <E extends Comparable<? super E>> TreeSet<E> generateTreeSet(E freshElement) {
+  static <E extends Comparable<? super E>> TreeSet<E> generateTreeSet(E freshElement) {
     TreeSet<E> set = Sets.newTreeSet();
     set.add(freshElement);
     return set;
   }
 
   @Generates
-  private static <E extends Comparable<? super E>> ImmutableSortedSet<E> generateImmutableSortedSet(
+  static <E extends Comparable<? super E>> ImmutableSortedSet<E> generateImmutableSortedSet(
       E freshElement) {
     return ImmutableSortedSet.of(freshElement);
   }
 
   @Generates
-  private static <E> Multiset<E> generateMultiset(E freshElement) {
+  static <E> Multiset<E> generateMultiset(@Nullable E freshElement) {
     return generateHashMultiset(freshElement);
   }
 
   @Generates
-  private static <E> HashMultiset<E> generateHashMultiset(E freshElement) {
+  static <E> HashMultiset<E> generateHashMultiset(@Nullable E freshElement) {
     HashMultiset<E> multiset = HashMultiset.create();
     multiset.add(freshElement);
     return multiset;
   }
 
   @Generates
-  private static <E> LinkedHashMultiset<E> generateLinkedHashMultiset(E freshElement) {
+  static <E> LinkedHashMultiset<E> generateLinkedHashMultiset(@Nullable E freshElement) {
     LinkedHashMultiset<E> multiset = LinkedHashMultiset.create();
     multiset.add(freshElement);
     return multiset;
   }
 
   @Generates
-  private static <E> ImmutableMultiset<E> generateImmutableMultiset(E freshElement) {
+  static <E> ImmutableMultiset<E> generateImmutableMultiset(E freshElement) {
     return ImmutableMultiset.of(freshElement);
   }
 
   @Generates
-  private static <E extends Comparable<E>> SortedMultiset<E> generateSortedMultiset(
-      E freshElement) {
+  static <E extends Comparable<E>> SortedMultiset<E> generateSortedMultiset(E freshElement) {
     return generateTreeMultiset(freshElement);
   }
 
   @Generates
-  private static <E extends Comparable<E>> TreeMultiset<E> generateTreeMultiset(E freshElement) {
+  static <E extends Comparable<E>> TreeMultiset<E> generateTreeMultiset(E freshElement) {
     TreeMultiset<E> multiset = TreeMultiset.create();
     multiset.add(freshElement);
     return multiset;
   }
 
   @Generates
-  private static <E extends Comparable<E>>
-      ImmutableSortedMultiset<E> generateImmutableSortedMultiset(E freshElement) {
+  static <E extends Comparable<E>> ImmutableSortedMultiset<E> generateImmutableSortedMultiset(
+      E freshElement) {
     return ImmutableSortedMultiset.of(freshElement);
   }
 
   @Generates
-  private static <K, V> Map<K, V> generateMap(K key, V value) {
+  static <K, V> Map<K, V> generateMap(@Nullable K key, @Nullable V value) {
     return generateHashdMap(key, value);
   }
 
   @Generates
-  private static <K, V> HashMap<K, V> generateHashdMap(K key, V value) {
+  static <K, V> HashMap<K, V> generateHashdMap(@Nullable K key, @Nullable V value) {
     return generateLinkedHashMap(key, value);
   }
 
   @Generates
-  private static <K, V> LinkedHashMap<K, V> generateLinkedHashMap(K key, V value) {
+  static <K, V> LinkedHashMap<K, V> generateLinkedHashMap(@Nullable K key, @Nullable V value) {
     LinkedHashMap<K, V> map = Maps.newLinkedHashMap();
     map.put(key, value);
     return map;
   }
 
   @Generates
-  private static <K, V> ImmutableMap<K, V> generateImmutableMap(K key, V value) {
+  static <K, V> ImmutableMap<K, V> generateImmutableMap(K key, V value) {
     return ImmutableMap.of(key, value);
   }
 
   @Empty
-  private static <K, V> ConcurrentMap<K, V> generateConcurrentMap() {
+  static <K, V> ConcurrentMap<K, V> generateConcurrentMap() {
     return Maps.newConcurrentMap();
   }
 
   @Generates
-  private static <K, V> ConcurrentMap<K, V> generateConcurrentMap(K key, V value) {
+  static <K, V> ConcurrentMap<K, V> generateConcurrentMap(K key, V value) {
     ConcurrentMap<K, V> map = Maps.newConcurrentMap();
     map.put(key, value);
     return map;
   }
 
   @Generates
-  private static <K extends Comparable<? super K>, V> SortedMap<K, V> generateSortedMap(
-      K key, V value) {
+  static <K extends Comparable<? super K>, V> SortedMap<K, V> generateSortedMap(
+      K key, @Nullable V value) {
     return generateNavigableMap(key, value);
   }
 
   @Generates
-  private static <K extends Comparable<? super K>, V> NavigableMap<K, V> generateNavigableMap(
-      K key, V value) {
+  static <K extends Comparable<? super K>, V> NavigableMap<K, V> generateNavigableMap(
+      K key, @Nullable V value) {
     return generateTreeMap(key, value);
   }
 
   @Generates
-  private static <K extends Comparable<? super K>, V> TreeMap<K, V> generateTreeMap(
-      K key, V value) {
+  static <K extends Comparable<? super K>, V> TreeMap<K, V> generateTreeMap(
+      K key, @Nullable V value) {
     TreeMap<K, V> map = Maps.newTreeMap();
     map.put(key, value);
     return map;
   }
 
   @Generates
-  private static <K extends Comparable<? super K>, V>
-      ImmutableSortedMap<K, V> generateImmutableSortedMap(K key, V value) {
+  static <K extends Comparable<? super K>, V> ImmutableSortedMap<K, V> generateImmutableSortedMap(
+      K key, V value) {
     return ImmutableSortedMap.of(key, value);
   }
 
   @Generates
-  private static <K, V> Multimap<K, V> generateMultimap(K key, V value) {
+  static <K, V> Multimap<K, V> generateMultimap(@Nullable K key, @Nullable V value) {
     return generateListMultimap(key, value);
   }
 
   @Generates
-  private static <K, V> ImmutableMultimap<K, V> generateImmutableMultimap(K key, V value) {
+  static <K, V> ImmutableMultimap<K, V> generateImmutableMultimap(K key, V value) {
     return ImmutableMultimap.of(key, value);
   }
 
   @Generates
-  private static <K, V> ListMultimap<K, V> generateListMultimap(K key, V value) {
+  static <K, V> ListMultimap<K, V> generateListMultimap(@Nullable K key, @Nullable V value) {
     return generateArrayListMultimap(key, value);
   }
 
   @Generates
-  private static <K, V> ArrayListMultimap<K, V> generateArrayListMultimap(K key, V value) {
+  static <K, V> ArrayListMultimap<K, V> generateArrayListMultimap(
+      @Nullable K key, @Nullable V value) {
     ArrayListMultimap<K, V> multimap = ArrayListMultimap.create();
     multimap.put(key, value);
     return multimap;
   }
 
   @Generates
-  private static <K, V> ImmutableListMultimap<K, V> generateImmutableListMultimap(K key, V value) {
+  static <K, V> ImmutableListMultimap<K, V> generateImmutableListMultimap(K key, V value) {
     return ImmutableListMultimap.of(key, value);
   }
 
   @Generates
-  private static <K, V> SetMultimap<K, V> generateSetMultimap(K key, V value) {
+  static <K, V> SetMultimap<K, V> generateSetMultimap(@Nullable K key, @Nullable V value) {
     return generateLinkedHashMultimap(key, value);
   }
 
   @Generates
-  private static <K, V> HashMultimap<K, V> generateHashMultimap(K key, V value) {
+  static <K, V> HashMultimap<K, V> generateHashMultimap(@Nullable K key, @Nullable V value) {
     HashMultimap<K, V> multimap = HashMultimap.create();
     multimap.put(key, value);
     return multimap;
   }
 
   @Generates
-  private static <K, V> LinkedHashMultimap<K, V> generateLinkedHashMultimap(K key, V value) {
+  static <K, V> LinkedHashMultimap<K, V> generateLinkedHashMultimap(
+      @Nullable K key, @Nullable V value) {
     LinkedHashMultimap<K, V> multimap = LinkedHashMultimap.create();
     multimap.put(key, value);
     return multimap;
   }
 
   @Generates
-  private static <K, V> ImmutableSetMultimap<K, V> generateImmutableSetMultimap(K key, V value) {
+  static <K, V> ImmutableSetMultimap<K, V> generateImmutableSetMultimap(K key, V value) {
     return ImmutableSetMultimap.of(key, value);
   }
 
   @Generates
-  private static <K, V> BiMap<K, V> generateBimap(K key, V value) {
+  static <K, V> BiMap<K, V> generateBimap(@Nullable K key, @Nullable V value) {
     return generateHashBiMap(key, value);
   }
 
   @Generates
-  private static <K, V> HashBiMap<K, V> generateHashBiMap(K key, V value) {
+  static <K, V> HashBiMap<K, V> generateHashBiMap(@Nullable K key, @Nullable V value) {
     HashBiMap<K, V> bimap = HashBiMap.create();
     bimap.put(key, value);
     return bimap;
   }
 
   @Generates
-  private static <K, V> ImmutableBiMap<K, V> generateImmutableBimap(K key, V value) {
+  static <K, V> ImmutableBiMap<K, V> generateImmutableBimap(K key, V value) {
     return ImmutableBiMap.of(key, value);
   }
 
   @Generates
-  private static <R, C, V> Table<R, C, V> generateTable(R row, C column, V value) {
+  static <R, C, V> Table<R, C, V> generateTable(
+      @Nullable R row, @Nullable C column, @Nullable V value) {
     return generateHashBasedTable(row, column, value);
   }
 
   @Generates
-  private static <R, C, V> HashBasedTable<R, C, V> generateHashBasedTable(
-      R row, C column, V value) {
+  static <R, C, V> HashBasedTable<R, C, V> generateHashBasedTable(
+      @Nullable R row, @Nullable C column, @Nullable V value) {
     HashBasedTable<R, C, V> table = HashBasedTable.create();
     table.put(row, column, value);
     return table;
@@ -944,14 +945,14 @@ private static <R, C, V> HashBasedTable<R, C, V> generateHashBasedTable(
 
   @SuppressWarnings("rawtypes") // TreeBasedTable.create() is defined as such
   @Generates
-  private static <R extends Comparable, C extends Comparable, V>
+  static <R extends Comparable, C extends Comparable, V>
       RowSortedTable<R, C, V> generateRowSortedTable(R row, C column, V value) {
     return generateTreeBasedTable(row, column, value);
   }
 
   @SuppressWarnings("rawtypes") // TreeBasedTable.create() is defined as such
   @Generates
-  private static <R extends Comparable, C extends Comparable, V>
+  static <R extends Comparable, C extends Comparable, V>
       TreeBasedTable<R, C, V> generateTreeBasedTable(R row, C column, V value) {
     TreeBasedTable<R, C, V> table = TreeBasedTable.create();
     table.put(row, column, value);
@@ -959,85 +960,84 @@ TreeBasedTable<R, C, V> generateTreeBasedTable(R row, C column, V value) {
   }
 
   @Generates
-  private static <R, C, V> ImmutableTable<R, C, V> generateImmutableTable(
-      R row, C column, V value) {
+  static <R, C, V> ImmutableTable<R, C, V> generateImmutableTable(R row, C column, V value) {
     return ImmutableTable.of(row, column, value);
   }
 
   // common.reflect
   @Generates
-  private TypeToken<?> generateTypeToken() {
+  TypeToken<?> generateTypeToken() {
     return TypeToken.of(generateClass());
   }
 
   // io types
   @Generates
-  private File generateFile() {
+  File generateFile() {
     return new File(generateString());
   }
 
   @Generates
-  private static ByteArrayInputStream generateByteArrayInputStream() {
+  static ByteArrayInputStream generateByteArrayInputStream() {
     return new ByteArrayInputStream(new byte[0]);
   }
 
   @Generates
-  private static InputStream generateInputStream() {
+  static InputStream generateInputStream() {
     return generateByteArrayInputStream();
   }
 
   @Generates
-  private StringReader generateStringReader() {
+  StringReader generateStringReader() {
     return new StringReader(generateString());
   }
 
   @Generates
-  private Reader generateReader() {
+  Reader generateReader() {
     return generateStringReader();
   }
 
   @Generates
-  private Readable generateReadable() {
+  Readable generateReadable() {
     return generateReader();
   }
 
   @Generates
-  private Buffer generateBuffer() {
+  Buffer generateBuffer() {
     return generateCharBuffer();
   }
 
   @Generates
-  private CharBuffer generateCharBuffer() {
+  CharBuffer generateCharBuffer() {
     return CharBuffer.allocate(generateInt());
   }
 
   @Generates
-  private ByteBuffer generateByteBuffer() {
+  ByteBuffer generateByteBuffer() {
     return ByteBuffer.allocate(generateInt());
   }
 
   @Generates
-  private ShortBuffer generateShortBuffer() {
+  ShortBuffer generateShortBuffer() {
     return ShortBuffer.allocate(generateInt());
   }
 
   @Generates
-  private IntBuffer generateIntBuffer() {
+  IntBuffer generateIntBuffer() {
     return IntBuffer.allocate(generateInt());
   }
 
   @Generates
-  private LongBuffer generateLongBuffer() {
+  LongBuffer generateLongBuffer() {
     return LongBuffer.allocate(generateInt());
   }
 
   @Generates
-  private FloatBuffer generateFloatBuffer() {
+  FloatBuffer generateFloatBuffer() {
     return FloatBuffer.allocate(generateInt());
   }
 
   @Generates
-  private DoubleBuffer generateDoubleBuffer() {
+  DoubleBuffer generateDoubleBuffer() {
     return DoubleBuffer.allocate(generateInt());
   }
 }
diff --git a/guava-testlib/src/com/google/common/testing/GcFinalization.java b/guava-testlib/src/com/google/common/testing/GcFinalization.java
index 015afea54809..da6aa2211b49 100644
--- a/guava-testlib/src/com/google/common/testing/GcFinalization.java
+++ b/guava-testlib/src/com/google/common/testing/GcFinalization.java
@@ -18,7 +18,6 @@
 
 import static java.util.concurrent.TimeUnit.SECONDS;
 
-import com.google.common.annotations.Beta;
 import com.google.common.annotations.GwtIncompatible;
 import com.google.errorprone.annotations.DoNotMock;
 import com.google.j2objc.annotations.J2ObjCIncompatible;
@@ -103,7 +102,6 @@
  * @author Martin Buchholz
  * @since 11.0
  */
-@Beta
 @GwtIncompatible
 @J2ObjCIncompatible // gc
 public final class GcFinalization {
@@ -138,8 +136,8 @@ public static void awaitDone(Future<?> future) {
     if (future.isDone()) {
       return;
     }
-    final long timeoutSeconds = timeoutSeconds();
-    final long deadline = System.nanoTime() + SECONDS.toNanos(timeoutSeconds);
+    long timeoutSeconds = timeoutSeconds();
+    long deadline = System.nanoTime() + SECONDS.toNanos(timeoutSeconds);
     do {
       System.runFinalization();
       if (future.isDone()) {
@@ -170,8 +168,8 @@ public static void awaitDone(FinalizationPredicate predicate) {
     if (predicate.isDone()) {
       return;
     }
-    final long timeoutSeconds = timeoutSeconds();
-    final long deadline = System.nanoTime() + SECONDS.toNanos(timeoutSeconds);
+    long timeoutSeconds = timeoutSeconds();
+    long deadline = System.nanoTime() + SECONDS.toNanos(timeoutSeconds);
     do {
       System.runFinalization();
       if (predicate.isDone()) {
@@ -198,8 +196,8 @@ public static void await(CountDownLatch latch) {
     if (latch.getCount() == 0) {
       return;
     }
-    final long timeoutSeconds = timeoutSeconds();
-    final long deadline = System.nanoTime() + SECONDS.toNanos(timeoutSeconds);
+    long timeoutSeconds = timeoutSeconds();
+    long deadline = System.nanoTime() + SECONDS.toNanos(timeoutSeconds);
     do {
       System.runFinalization();
       if (latch.getCount() == 0) {
@@ -222,13 +220,14 @@ public static void await(CountDownLatch latch) {
    * Creates a garbage object that counts down the latch in its finalizer. Sequestered into a
    * separate method to make it somewhat more likely to be unreachable.
    */
-  private static void createUnreachableLatchFinalizer(final CountDownLatch latch) {
-    new Object() {
-      @Override
-      protected void finalize() {
-        latch.countDown();
-      }
-    };
+  private static void createUnreachableLatchFinalizer(CountDownLatch latch) {
+    Object unused =
+        new Object() {
+          @Override
+          protected void finalize() {
+            latch.countDown();
+          }
+        };
   }
 
   /**
@@ -263,7 +262,7 @@ public interface FinalizationPredicate {
    *
    * @throws RuntimeException if timed out or interrupted while waiting
    */
-  public static void awaitClear(final WeakReference<?> ref) {
+  public static void awaitClear(WeakReference<?> ref) {
     awaitDone(
         new FinalizationPredicate() {
           @Override
@@ -296,9 +295,9 @@ public boolean isDone() {
    * @since 12.0
    */
   public static void awaitFullGc() {
-    final CountDownLatch finalizerRan = new CountDownLatch(1);
+    CountDownLatch finalizerRan = new CountDownLatch(1);
     WeakReference<Object> ref =
-        new WeakReference<Object>(
+        new WeakReference<>(
             new Object() {
               @Override
               protected void finalize() {
diff --git a/guava-testlib/src/com/google/common/testing/NullPointerTester.java b/guava-testlib/src/com/google/common/testing/NullPointerTester.java
index cd0dd15a6137..3eb317605f30 100644
--- a/guava-testlib/src/com/google/common/testing/NullPointerTester.java
+++ b/guava-testlib/src/com/google/common/testing/NullPointerTester.java
@@ -19,7 +19,6 @@
 import static com.google.common.base.Preconditions.checkArgument;
 import static com.google.common.base.Preconditions.checkNotNull;
 
-import com.google.common.annotations.Beta;
 import com.google.common.annotations.GwtIncompatible;
 import com.google.common.base.Converter;
 import com.google.common.base.Objects;
@@ -34,6 +33,7 @@
 import com.google.common.reflect.Reflection;
 import com.google.common.reflect.TypeToken;
 import java.lang.annotation.Annotation;
+import java.lang.reflect.AnnotatedType;
 import java.lang.reflect.Constructor;
 import java.lang.reflect.InvocationTargetException;
 import java.lang.reflect.Member;
@@ -41,9 +41,11 @@
 import java.lang.reflect.Modifier;
 import java.lang.reflect.ParameterizedType;
 import java.lang.reflect.Type;
+import java.lang.reflect.TypeVariable;
 import java.util.Arrays;
 import java.util.List;
 import java.util.concurrent.ConcurrentMap;
+import java.util.function.Function;
 import junit.framework.Assert;
 import junit.framework.AssertionFailedError;
 import org.checkerframework.checker.nullness.qual.Nullable;
@@ -52,7 +54,7 @@
  * A test utility that verifies that your methods and constructors throw {@link
  * NullPointerException} or {@link UnsupportedOperationException} whenever null is passed to a
  * parameter whose declaration or type isn't annotated with an annotation with the simple name
- * {@code Nullable}, {@lcode CheckForNull}, {@link NullableType}, or {@link NullableDecl}.
+ * {@code Nullable}, {@code CheckForNull}, {@link NullableType}, or {@link NullableDecl}.
  *
  * <p>The tested methods and constructors are invoked -- each time with one parameter being null and
  * the rest not null -- and the test fails if no expected exception is thrown. {@code
@@ -65,7 +67,6 @@
  * @author Kevin Bourrillion
  * @since 10.0
  */
-@Beta
 @GwtIncompatible
 public final class NullPointerTester {
 
@@ -473,7 +474,8 @@ static boolean isPrimitiveOrNullable(Parameter param) {
   }
 
   private static final ImmutableSet<String> NULLABLE_ANNOTATION_SIMPLE_NAMES =
-      ImmutableSet.of("CheckForNull", "Nullable", "NullableDecl", "NullableType");
+      ImmutableSet.of(
+          "CheckForNull", "Nullable", "NullableDecl", "NullableType", "ParametricNullness");
 
   static boolean isNullable(Invokable<?, ?> invokable) {
     return isNullable(invokable.getAnnotatedReturnType().getAnnotations())
@@ -482,7 +484,24 @@ static boolean isNullable(Invokable<?, ?> invokable) {
 
   static boolean isNullable(Parameter param) {
     return isNullable(param.getAnnotatedType().getAnnotations())
-        || isNullable(param.getAnnotations());
+        || isNullable(param.getAnnotations())
+        || isNullableTypeVariable(param.getAnnotatedType().getType());
+  }
+
+  private static boolean isNullableTypeVariable(Type type) {
+    if (!(type instanceof TypeVariable)) {
+      return false;
+    }
+    TypeVariable<?> var = (TypeVariable<?>) type;
+    AnnotatedType[] bounds = GET_ANNOTATED_BOUNDS.apply(var);
+    for (AnnotatedType bound : bounds) {
+      // Until Java 15, the isNullableTypeVariable case here won't help:
+      // https://bugs.openjdk.java.net/browse/JDK-8202469
+      if (isNullable(bound.getAnnotations()) || isNullableTypeVariable(bound.getType())) {
+        return true;
+      }
+    }
+    return false;
   }
 
   private static boolean isNullable(Annotation[] annotations) {
@@ -494,12 +513,33 @@ private static boolean isNullable(Annotation[] annotations) {
     return false;
   }
 
+  // This is currently required because of j2objc restrictions.
+  private static final Function<TypeVariable<?>, AnnotatedType[]> GET_ANNOTATED_BOUNDS =
+      initGetAnnotatedBounds();
+
+  private static Function<TypeVariable<?>, AnnotatedType[]> initGetAnnotatedBounds() {
+    AnnotatedType[] noBounds = new AnnotatedType[0];
+    Method getAnnotatedBounds;
+    try {
+      getAnnotatedBounds = TypeVariable.class.getMethod("getAnnotatedBounds");
+    } catch (ReflectiveOperationException e) {
+      return v -> noBounds;
+    }
+    return v -> {
+      try {
+        return (AnnotatedType[]) getAnnotatedBounds.invoke(v);
+      } catch (ReflectiveOperationException e) {
+        return noBounds;
+      }
+    };
+  }
+
   private boolean isIgnored(Member member) {
     return member.isSynthetic() || ignoredMembers.contains(member) || isEquals(member);
   }
 
   /**
-   * Returns true if the the given member is a method that overrides {@link Object#equals(Object)}.
+   * Returns true if the given member is a method that overrides {@link Object#equals(Object)}.
    *
    * <p>The documentation for {@link Object#equals} says it should accept null, so don't require an
    * explicit {@code @Nullable} annotation (see <a
diff --git a/guava-testlib/src/com/google/common/testing/RelationshipTester.java b/guava-testlib/src/com/google/common/testing/RelationshipTester.java
index 5adf01091a85..d5b9b6a18693 100644
--- a/guava-testlib/src/com/google/common/testing/RelationshipTester.java
+++ b/guava-testlib/src/com/google/common/testing/RelationshipTester.java
@@ -147,7 +147,7 @@ private void assertWithTemplate(String template, Item<T> item, Item<T> other, bo
   }
 
   private Item<T> getItem(int groupNumber, int itemNumber) {
-    return new Item<T>(groups.get(groupNumber).get(itemNumber), groupNumber, itemNumber);
+    return new Item<>(groups.get(groupNumber).get(itemNumber), groupNumber, itemNumber);
   }
 
   static final class Item<T> {
diff --git a/guava-testlib/src/com/google/common/testing/SerializableTester.java b/guava-testlib/src/com/google/common/testing/SerializableTester.java
index 62980764d65f..c4e6d236ee7e 100644
--- a/guava-testlib/src/com/google/common/testing/SerializableTester.java
+++ b/guava-testlib/src/com/google/common/testing/SerializableTester.java
@@ -16,7 +16,6 @@
 
 package com.google.common.testing;
 
-import com.google.common.annotations.Beta;
 import com.google.common.annotations.GwtCompatible;
 import junit.framework.Assert;
 import junit.framework.AssertionFailedError;
@@ -32,7 +31,6 @@
  * @author Mike Bostock
  * @since 10.0
  */
-@Beta
 @GwtCompatible // but no-op!
 public final class SerializableTester {
   private SerializableTester() {}
@@ -52,7 +50,6 @@ private SerializableTester() {}
    * @throws RuntimeException if the specified object was not successfully serialized or
    *     deserialized
    */
-  @SuppressWarnings("unchecked")
   public static <T> T reserialize(T object) {
     return Platform.reserialize(object);
   }
diff --git a/guava-testlib/src/com/google/common/testing/TestLogHandler.java b/guava-testlib/src/com/google/common/testing/TestLogHandler.java
index e63d11fa5067..41dca2ec8b8d 100644
--- a/guava-testlib/src/com/google/common/testing/TestLogHandler.java
+++ b/guava-testlib/src/com/google/common/testing/TestLogHandler.java
@@ -16,7 +16,6 @@
 
 package com.google.common.testing;
 
-import com.google.common.annotations.Beta;
 import com.google.common.annotations.GwtCompatible;
 import java.util.ArrayList;
 import java.util.Collections;
@@ -52,7 +51,6 @@
  * @author Kevin Bourrillion
  * @since 10.0
  */
-@Beta
 @GwtCompatible
 public class TestLogHandler extends Handler {
   /** We will keep a private list of all logged records */
diff --git a/guava-testlib/src/com/google/common/util/concurrent/testing/AbstractListenableFutureTest.java b/guava-testlib/src/com/google/common/util/concurrent/testing/AbstractListenableFutureTest.java
index 2ba751537396..b5bec2c094bd 100644
--- a/guava-testlib/src/com/google/common/util/concurrent/testing/AbstractListenableFutureTest.java
+++ b/guava-testlib/src/com/google/common/util/concurrent/testing/AbstractListenableFutureTest.java
@@ -16,6 +16,9 @@
 
 package com.google.common.util.concurrent.testing;
 
+import static java.util.concurrent.TimeUnit.MILLISECONDS;
+import static java.util.concurrent.TimeUnit.SECONDS;
+
 import com.google.common.annotations.Beta;
 import com.google.common.annotations.GwtIncompatible;
 import com.google.common.util.concurrent.ListenableFuture;
@@ -68,21 +71,18 @@ public void testGetBlocksUntilValueAvailable() throws Throwable {
     assertFalse(future.isDone());
     assertFalse(future.isCancelled());
 
-    final CountDownLatch successLatch = new CountDownLatch(1);
-    final Throwable[] badness = new Throwable[1];
+    CountDownLatch successLatch = new CountDownLatch(1);
+    Throwable[] badness = new Throwable[1];
 
     // Wait on the future in a separate thread.
     new Thread(
-            new Runnable() {
-              @Override
-              public void run() {
-                try {
-                  assertSame(Boolean.TRUE, future.get());
-                  successLatch.countDown();
-                } catch (Throwable t) {
-                  t.printStackTrace();
-                  badness[0] = t;
-                }
+            () -> {
+              try {
+                assertSame(Boolean.TRUE, future.get());
+                successLatch.countDown();
+              } catch (Throwable t) {
+                t.printStackTrace();
+                badness[0] = t;
               }
             })
         .start();
@@ -90,7 +90,7 @@ public void run() {
     // Release the future value.
     latch.countDown();
 
-    assertTrue(successLatch.await(10, TimeUnit.SECONDS));
+    assertTrue(successLatch.await(10, SECONDS));
 
     if (badness[0] != null) {
       throw badness[0];
@@ -105,7 +105,7 @@ public void testTimeoutOnGetWorksCorrectly() throws InterruptedException, Execut
 
     // The task thread waits for the latch, so we expect a timeout here.
     try {
-      future.get(20, TimeUnit.MILLISECONDS);
+      future.get(20, MILLISECONDS);
       fail("Should have timed out trying to get the value.");
     } catch (TimeoutException expected) {
     } finally {
@@ -123,20 +123,17 @@ public void testCanceledFutureThrowsCancellation() throws Exception {
     assertFalse(future.isDone());
     assertFalse(future.isCancelled());
 
-    final CountDownLatch successLatch = new CountDownLatch(1);
+    CountDownLatch successLatch = new CountDownLatch(1);
 
     // Run cancellation in a separate thread as an extra thread-safety test.
     new Thread(
-            new Runnable() {
-              @Override
-              public void run() {
-                try {
-                  future.get();
-                } catch (CancellationException expected) {
-                  successLatch.countDown();
-                } catch (Exception ignored) {
-                  // All other errors are ignored, we expect a cancellation.
-                }
+            () -> {
+              try {
+                future.get();
+              } catch (CancellationException expected) {
+                successLatch.countDown();
+              } catch (Exception ignored) {
+                // All other errors are ignored, we expect a cancellation.
               }
             })
         .start();
@@ -149,37 +146,27 @@ public void run() {
     assertTrue(future.isDone());
     assertTrue(future.isCancelled());
 
-    assertTrue(successLatch.await(200, TimeUnit.MILLISECONDS));
+    assertTrue(successLatch.await(200, MILLISECONDS));
 
     latch.countDown();
   }
 
   public void testListenersNotifiedOnError() throws Exception {
-    final CountDownLatch successLatch = new CountDownLatch(1);
-    final CountDownLatch listenerLatch = new CountDownLatch(1);
+    CountDownLatch successLatch = new CountDownLatch(1);
+    CountDownLatch listenerLatch = new CountDownLatch(1);
 
     ExecutorService exec = Executors.newCachedThreadPool();
 
-    future.addListener(
-        new Runnable() {
-          @Override
-          public void run() {
-            listenerLatch.countDown();
-          }
-        },
-        exec);
+    future.addListener(listenerLatch::countDown, exec);
 
     new Thread(
-            new Runnable() {
-              @Override
-              public void run() {
-                try {
-                  future.get();
-                } catch (CancellationException expected) {
-                  successLatch.countDown();
-                } catch (Exception ignored) {
-                  // No success latch count down.
-                }
+            () -> {
+              try {
+                future.get();
+              } catch (CancellationException expected) {
+                successLatch.countDown();
+              } catch (Exception ignored) {
+                // No success latch count down.
               }
             })
         .start();
@@ -189,13 +176,13 @@ public void run() {
     assertTrue(future.isCancelled());
     assertTrue(future.isDone());
 
-    assertTrue(successLatch.await(200, TimeUnit.MILLISECONDS));
-    assertTrue(listenerLatch.await(200, TimeUnit.MILLISECONDS));
+    assertTrue(successLatch.await(200, MILLISECONDS));
+    assertTrue(listenerLatch.await(200, MILLISECONDS));
 
     latch.countDown();
 
     exec.shutdown();
-    exec.awaitTermination(100, TimeUnit.MILLISECONDS);
+    exec.awaitTermination(100, MILLISECONDS);
   }
 
   /**
@@ -209,7 +196,7 @@ public void testAllListenersCompleteSuccessfully()
     ExecutorService exec = Executors.newCachedThreadPool();
 
     int listenerCount = 20;
-    final CountDownLatch listenerLatch = new CountDownLatch(listenerCount);
+    CountDownLatch listenerLatch = new CountDownLatch(listenerCount);
 
     // Test that listeners added both before and after the value is available
     // get called correctly.
@@ -217,31 +204,17 @@ public void testAllListenersCompleteSuccessfully()
 
       // Right in the middle start up a thread to close the latch.
       if (i == 10) {
-        new Thread(
-                new Runnable() {
-                  @Override
-                  public void run() {
-                    latch.countDown();
-                  }
-                })
-            .start();
+        new Thread(() -> latch.countDown()).start();
       }
 
-      future.addListener(
-          new Runnable() {
-            @Override
-            public void run() {
-              listenerLatch.countDown();
-            }
-          },
-          exec);
+      future.addListener(listenerLatch::countDown, exec);
     }
 
     assertSame(Boolean.TRUE, future.get());
     // Wait for the listener latch to complete.
-    listenerLatch.await(500, TimeUnit.MILLISECONDS);
+    listenerLatch.await(500, MILLISECONDS);
 
     exec.shutdown();
-    exec.awaitTermination(500, TimeUnit.MILLISECONDS);
+    exec.awaitTermination(500, MILLISECONDS);
   }
 }
diff --git a/guava-testlib/src/com/google/common/util/concurrent/testing/MockFutureListener.java b/guava-testlib/src/com/google/common/util/concurrent/testing/MockFutureListener.java
index fc3ed21f1ba9..a2fe4f447a79 100644
--- a/guava-testlib/src/com/google/common/util/concurrent/testing/MockFutureListener.java
+++ b/guava-testlib/src/com/google/common/util/concurrent/testing/MockFutureListener.java
@@ -17,13 +17,13 @@
 package com.google.common.util.concurrent.testing;
 
 import static com.google.common.util.concurrent.MoreExecutors.directExecutor;
+import static java.util.concurrent.TimeUnit.SECONDS;
 
 import com.google.common.annotations.Beta;
 import com.google.common.annotations.GwtIncompatible;
 import com.google.common.util.concurrent.ListenableFuture;
 import java.util.concurrent.CountDownLatch;
 import java.util.concurrent.ExecutionException;
-import java.util.concurrent.TimeUnit;
 import junit.framework.Assert;
 
 /**
@@ -59,7 +59,7 @@ public void run() {
    */
   public void assertSuccess(Object expectedData) throws Throwable {
     // Verify that the listener executed in a reasonable amount of time.
-    Assert.assertTrue(countDownLatch.await(1L, TimeUnit.SECONDS));
+    Assert.assertTrue(countDownLatch.await(1L, SECONDS));
 
     try {
       Assert.assertEquals(expectedData, future.get());
@@ -75,7 +75,7 @@ public void assertSuccess(Object expectedData) throws Throwable {
    */
   public void assertException(Throwable expectedCause) throws Exception {
     // Verify that the listener executed in a reasonable amount of time.
-    Assert.assertTrue(countDownLatch.await(1L, TimeUnit.SECONDS));
+    Assert.assertTrue(countDownLatch.await(1L, SECONDS));
 
     try {
       future.get();
@@ -88,6 +88,6 @@ public void assertException(Throwable expectedCause) throws Exception {
   public void assertTimeout() throws Exception {
     // Verify that the listener does not get called in a reasonable amount of
     // time.
-    Assert.assertFalse(countDownLatch.await(1L, TimeUnit.SECONDS));
+    Assert.assertFalse(countDownLatch.await(1L, SECONDS));
   }
 }
diff --git a/guava-testlib/src/com/google/common/util/concurrent/testing/SameThreadScheduledExecutorService.java b/guava-testlib/src/com/google/common/util/concurrent/testing/SameThreadScheduledExecutorService.java
index c232218fb4bf..25b7ef791c00 100644
--- a/guava-testlib/src/com/google/common/util/concurrent/testing/SameThreadScheduledExecutorService.java
+++ b/guava-testlib/src/com/google/common/util/concurrent/testing/SameThreadScheduledExecutorService.java
@@ -140,11 +140,11 @@ public ListenableScheduledFuture<?> schedule(Runnable command, long delay, TimeU
 
   @Override
   public <V> ListenableScheduledFuture<V> schedule(
-      final Callable<V> callable, long delay, TimeUnit unit) {
+      Callable<V> callable, long delay, TimeUnit unit) {
     Preconditions.checkNotNull(callable, "callable must not be null!");
     Preconditions.checkNotNull(unit, "unit must not be null!");
     ListenableFuture<V> delegateFuture = submit(callable);
-    return new ImmediateScheduledFuture<V>(delegateFuture);
+    return new ImmediateScheduledFuture<>(delegateFuture);
   }
 
   private static class ImmediateScheduledFuture<V> extends SimpleForwardingListenableFuture<V>
diff --git a/guava-testlib/src/com/google/common/util/concurrent/testing/TestingExecutors.java b/guava-testlib/src/com/google/common/util/concurrent/testing/TestingExecutors.java
index 421243043245..dc2c40d37492 100644
--- a/guava-testlib/src/com/google/common/util/concurrent/testing/TestingExecutors.java
+++ b/guava-testlib/src/com/google/common/util/concurrent/testing/TestingExecutors.java
@@ -16,6 +16,8 @@
 
 package com.google.common.util.concurrent.testing;
 
+import static java.util.concurrent.TimeUnit.NANOSECONDS;
+
 import com.google.common.annotations.Beta;
 import com.google.common.annotations.GwtIncompatible;
 import com.google.common.collect.ImmutableList;
@@ -153,7 +155,7 @@ private static class NeverScheduledFuture<V> extends AbstractFuture<V>
         implements ListenableScheduledFuture<V> {
 
       static <V> NeverScheduledFuture<V> create() {
-        return new NeverScheduledFuture<V>();
+        return new NeverScheduledFuture<>();
       }
 
       @Override
@@ -163,7 +165,7 @@ public long getDelay(TimeUnit unit) {
 
       @Override
       public int compareTo(Delayed other) {
-        return Longs.compare(getDelay(TimeUnit.NANOSECONDS), other.getDelay(TimeUnit.NANOSECONDS));
+        return Longs.compare(getDelay(NANOSECONDS), other.getDelay(NANOSECONDS));
       }
     }
   }
diff --git a/guava-testlib/test/com/google/common/collect/testing/FeatureSpecificTestSuiteBuilderTest.java b/guava-testlib/test/com/google/common/collect/testing/FeatureSpecificTestSuiteBuilderTest.java
index dc0fe37b4471..4d617d64db09 100644
--- a/guava-testlib/test/com/google/common/collect/testing/FeatureSpecificTestSuiteBuilderTest.java
+++ b/guava-testlib/test/com/google/common/collect/testing/FeatureSpecificTestSuiteBuilderTest.java
@@ -27,7 +27,7 @@
 /** @author Max Ross */
 public class FeatureSpecificTestSuiteBuilderTest extends TestCase {
 
-  static boolean testWasRun;
+  private static boolean testWasRun;
 
   @Override
   protected void setUp() throws Exception {
@@ -52,7 +52,7 @@ protected List<Class<? extends AbstractTester>> getTesters() {
   }
 
   public void testLifecycle() {
-    final boolean setUp[] = {false};
+    boolean[] setUp = {false};
     Runnable setUpRunnable =
         new Runnable() {
           @Override
@@ -61,7 +61,7 @@ public void run() {
           }
         };
 
-    final boolean tearDown[] = {false};
+    boolean[] tearDown = {false};
     Runnable tearDownRunnable =
         new Runnable() {
           @Override
diff --git a/guava-testlib/test/com/google/common/collect/testing/MapTestSuiteBuilderTests.java b/guava-testlib/test/com/google/common/collect/testing/MapTestSuiteBuilderTests.java
index a7a39cd633ba..5fd0d0368d96 100644
--- a/guava-testlib/test/com/google/common/collect/testing/MapTestSuiteBuilderTests.java
+++ b/guava-testlib/test/com/google/common/collect/testing/MapTestSuiteBuilderTests.java
@@ -26,6 +26,11 @@
 import com.google.common.collect.testing.features.CollectionSize;
 import com.google.common.collect.testing.features.Feature;
 import com.google.common.collect.testing.features.MapFeature;
+import com.google.common.reflect.Reflection;
+import java.io.Serializable;
+import java.lang.reflect.InvocationHandler;
+import java.lang.reflect.InvocationTargetException;
+import java.lang.reflect.Method;
 import java.util.AbstractMap;
 import java.util.AbstractSet;
 import java.util.Collection;
@@ -36,6 +41,7 @@
 import java.util.Map;
 import java.util.Map.Entry;
 import java.util.Set;
+import java.util.concurrent.atomic.AtomicBoolean;
 import java.util.function.Predicate;
 import junit.framework.Test;
 import junit.framework.TestCase;
@@ -53,6 +59,7 @@ public static Test suite() {
     TestSuite suite = new TestSuite(MapTestSuiteBuilderTests.class.getSimpleName());
     suite.addTest(testsForHashMapNullKeysForbidden());
     suite.addTest(testsForHashMapNullValuesForbidden());
+    suite.addTest(testsForSetUpTearDown());
     return suite;
   }
 
@@ -263,4 +270,89 @@ public String put(String key, String value) {
         "HashMap w/out null values",
         ALLOWS_NULL_KEYS);
   }
+
+  /**
+   * Map generator that verifies that {@code setUp()} methods are called in all the test cases. The
+   * {@code setUpRan} parameter is set true by the {@code setUp} that every test case is supposed to
+   * have registered, and set false by the {@code tearDown}. We use a dynamic proxy to intercept all
+   * of the {@code Map} method calls and check that {@code setUpRan} is true.
+   */
+  private static class CheckSetUpHashMapGenerator extends WrappedHashMapGenerator {
+    private final AtomicBoolean setUpRan;
+
+    CheckSetUpHashMapGenerator(AtomicBoolean setUpRan) {
+      this.setUpRan = setUpRan;
+    }
+
+    @Override
+    Map<String, String> wrap(HashMap<String, String> map) {
+      @SuppressWarnings("unchecked")
+      Map<String, String> proxy =
+          Reflection.newProxy(Map.class, new CheckSetUpInvocationHandler(map, setUpRan));
+      return proxy;
+    }
+  }
+
+  /**
+   * Intercepts calls to a {@code Map} to check that {@code setUpRan} is true when they happen. Then
+   * forwards the calls to the underlying {@code Map}.
+   */
+  private static class CheckSetUpInvocationHandler implements InvocationHandler, Serializable {
+    private final Map<String, String> map;
+    private final AtomicBoolean setUpRan;
+
+    CheckSetUpInvocationHandler(Map<String, String> map, AtomicBoolean setUpRan) {
+      this.map = map;
+      this.setUpRan = setUpRan;
+    }
+
+    @Override
+    public Object invoke(Object target, Method method, Object[] args) throws Throwable {
+      assertTrue("setUp should have run", setUpRan.get());
+      try {
+        return method.invoke(map, args);
+      } catch (InvocationTargetException e) {
+        throw e.getCause();
+      } catch (IllegalAccessException e) {
+        throw newLinkageError(e);
+      }
+    }
+  }
+
+  /** Verifies that {@code setUp} and {@code tearDown} are called in all map test cases. */
+  private static Test testsForSetUpTearDown() {
+    final AtomicBoolean setUpRan = new AtomicBoolean();
+    Runnable setUp =
+        new Runnable() {
+          @Override
+          public void run() {
+            assertFalse("previous tearDown should have run before setUp", setUpRan.getAndSet(true));
+          }
+        };
+    Runnable tearDown =
+        new Runnable() {
+          @Override
+          public void run() {
+            assertTrue("setUp should have run", setUpRan.getAndSet(false));
+          }
+        };
+    return MapTestSuiteBuilder.using(new CheckSetUpHashMapGenerator(setUpRan))
+        .named("setUpTearDown")
+        .withFeatures(
+            MapFeature.GENERAL_PURPOSE,
+            MapFeature.ALLOWS_NULL_KEYS,
+            MapFeature.ALLOWS_NULL_VALUES,
+            CollectionFeature.SERIALIZABLE,
+            CollectionFeature.SUPPORTS_ITERATOR_REMOVE,
+            CollectionSize.ANY)
+        .withSetUp(setUp)
+        .withTearDown(tearDown)
+        .createTestSuite();
+  }
+
+  private static LinkageError newLinkageError(Throwable cause) {
+    LinkageError error = new LinkageError(cause.toString());
+    error.initCause(cause);
+    return error;
+  }
 }
diff --git a/guava-testlib/test/com/google/common/testing/EquivalenceTesterTest.java b/guava-testlib/test/com/google/common/testing/EquivalenceTesterTest.java
index d612b2c2c876..865c198e727f 100644
--- a/guava-testlib/test/com/google/common/testing/EquivalenceTesterTest.java
+++ b/guava-testlib/test/com/google/common/testing/EquivalenceTesterTest.java
@@ -237,7 +237,7 @@ void expectHash(Object object, int hash) {
     void replay() {
       checkRecording();
       equivalentExpectations = equivalentExpectationsBuilder.build();
-      hashExpectations = hashExpectationsBuilder.build();
+      hashExpectations = hashExpectationsBuilder.buildOrThrow();
     }
 
     @Override
diff --git a/guava-testlib/test/com/google/common/testing/NullPointerTesterTest.java b/guava-testlib/test/com/google/common/testing/NullPointerTesterTest.java
index 1877da34933b..a5a20ec3ad61 100644
--- a/guava-testlib/test/com/google/common/testing/NullPointerTesterTest.java
+++ b/guava-testlib/test/com/google/common/testing/NullPointerTesterTest.java
@@ -1484,4 +1484,47 @@ public void testConstructor_ShouldFail() throws Exception {
     }
     fail("Should detect problem in " + FailOnOneOfTwoConstructors.class.getSimpleName());
   }
+
+  public static class NullBounds<T extends @Nullable Object, U extends T, X> {
+    boolean xWasCalled;
+
+    @SuppressWarnings("unused") // Called by reflection
+    public void x(X x) {
+      xWasCalled = true;
+      checkNotNull(x);
+    }
+
+    @SuppressWarnings("unused") // Called by reflection
+    public void t(T t) {
+      fail("Method with parameter <T extends @Nullable Object> should not be called");
+    }
+
+    @SuppressWarnings("unused") // Called by reflection
+    public void u(U u) {
+      fail(
+          "Method with parameter <U extends T> where <T extends @Nullable Object> should not be"
+              + " called");
+    }
+
+    @SuppressWarnings("unused") // Called by reflection
+    public <A extends @Nullable Object> void a(A a) {
+      fail("Method with parameter <A extends @Nullable Object> should not be called");
+    }
+
+    @SuppressWarnings("unused") // Called by reflection
+    public <A extends B, B extends @Nullable Object> void b(A a) {
+      fail(
+          "Method with parameter <A extends B> where <B extends @Nullable Object> should not be"
+              + " called");
+    }
+  }
+
+  public void testNullBounds() {
+    // NullBounds has methods whose parameters are type variables that have
+    // "extends @Nullable Object" as a bound. This test ensures that NullPointerTester considers
+    // those parameters to be @Nullable, so it won't call the methods.
+    NullBounds<?, ?, ?> nullBounds = new NullBounds<>();
+    new NullPointerTester().testAllPublicInstanceMethods(nullBounds);
+    assertThat(nullBounds.xWasCalled).isTrue();
+  }
 }
diff --git a/guava-tests/benchmark/com/google/common/base/StringsRepeatBenchmark.java b/guava-tests/benchmark/com/google/common/base/StringsRepeatBenchmark.java
index 30261da5d8ff..16e00ef3d2e2 100644
--- a/guava-tests/benchmark/com/google/common/base/StringsRepeatBenchmark.java
+++ b/guava-tests/benchmark/com/google/common/base/StringsRepeatBenchmark.java
@@ -40,7 +40,7 @@ void setUp() {
   }
 
   @Benchmark
-  void oldRepeat(int reps) {
+  void oldRepeat(long reps) {
     for (int i = 0; i < reps; i++) {
       String x = oldRepeat(originalString, count);
       if (x.length() != (originalString.length() * count)) {
@@ -62,7 +62,7 @@ private static String oldRepeat(String string, int count) {
   }
 
   @Benchmark
-  void mikeRepeat(int reps) {
+  void mikeRepeat(long reps) {
     for (int i = 0; i < reps; i++) {
       String x = mikeRepeat(originalString, count);
       if (x.length() != (originalString.length() * count)) {
@@ -95,7 +95,7 @@ private static String mikeRepeat(String string, int count) {
   }
 
   @Benchmark
-  void martinRepeat(int reps) {
+  void martinRepeat(long reps) {
     for (int i = 0; i < reps; i++) {
       String x = martinRepeat(originalString, count);
       if (x.length() != (originalString.length() * count)) {
diff --git a/guava-tests/benchmark/com/google/common/base/ToStringHelperBenchmark.java b/guava-tests/benchmark/com/google/common/base/ToStringHelperBenchmark.java
index b2c24eca3ebd..a555fc4d36a7 100644
--- a/guava-tests/benchmark/com/google/common/base/ToStringHelperBenchmark.java
+++ b/guava-tests/benchmark/com/google/common/base/ToStringHelperBenchmark.java
@@ -136,4 +136,6 @@ int toString(int reps) {
     }
     return dummy;
   }
+
+  // When omitEmptyValues() is released, remove this method and add a new @Param "omitEmptyValues".
 }
diff --git a/guava-tests/benchmark/com/google/common/collect/ImmutableSetHashFloodingDetectionBenchmark.java b/guava-tests/benchmark/com/google/common/collect/ImmutableSetHashFloodingDetectionBenchmark.java
index 9e45916b4cc3..9e43bb71d7ce 100644
--- a/guava-tests/benchmark/com/google/common/collect/ImmutableSetHashFloodingDetectionBenchmark.java
+++ b/guava-tests/benchmark/com/google/common/collect/ImmutableSetHashFloodingDetectionBenchmark.java
@@ -140,6 +140,50 @@ boolean hashFloodingDetected(Object[] hashTable) {
         }
         return false;
       }
+    },
+    SKIPPING {
+      int maxRunBeforeFallback(int tableSize) {
+        return 13 * IntMath.log2(tableSize, RoundingMode.UNNECESSARY);
+      }
+
+      @Override
+      boolean hashFloodingDetected(Object[] hashTable) {
+        int maxRunBeforeFallback = maxRunBeforeFallback(hashTable.length);
+        int mask = hashTable.length - 1;
+
+        // Invariant: all elements at indices in [knownRunStart, knownRunEnd) are nonnull.
+        // If knownRunStart == knownRunEnd, this is vacuously true.
+        // When knownRunEnd exceeds hashTable.length, it "wraps", detecting runs around the end
+        // of the table.
+        int knownRunStart = 0;
+        int knownRunEnd = 0;
+
+        outerLoop:
+        while (knownRunStart < hashTable.length) {
+          if (knownRunStart == knownRunEnd && hashTable[knownRunStart] == null) {
+            if (hashTable[(knownRunStart + maxRunBeforeFallback - 1) & mask] == null) {
+              // There are only maxRunBeforeFallback - 1 elements between here and there,
+              // so even if they were all nonnull, we wouldn't detect a hash flood.  Therefore,
+              // we can skip them all.
+              knownRunStart += maxRunBeforeFallback;
+            } else {
+              knownRunStart++; // the only case in which maxRunEnd doesn't increase by mRBF
+              // happens about f * (1-f) for f = DESIRED_LOAD_FACTOR, so around 21% of the time
+            }
+            knownRunEnd = knownRunStart;
+          } else {
+            for (int j = knownRunStart + maxRunBeforeFallback - 1; j >= knownRunEnd; j--) {
+              if (hashTable[j & mask] == null) {
+                knownRunEnd = knownRunStart + maxRunBeforeFallback;
+                knownRunStart = j + 1;
+                continue outerLoop;
+              }
+            }
+            return true;
+          }
+        }
+        return false;
+      }
     };
 
     abstract boolean hashFloodingDetected(Object[] array);
diff --git a/guava-tests/benchmark/com/google/common/collect/MapBenchmark.java b/guava-tests/benchmark/com/google/common/collect/MapBenchmark.java
index f10b94ea6e10..cd8e24b1ef76 100644
--- a/guava-tests/benchmark/com/google/common/collect/MapBenchmark.java
+++ b/guava-tests/benchmark/com/google/common/collect/MapBenchmark.java
@@ -139,7 +139,7 @@ Map<Element, Element> create(Collection<Element> keys) {
         for (Element element : keys) {
           builder.put(element, element);
         }
-        return builder.build();
+        return builder.buildOrThrow();
       }
     },
     ImmutableSorted {
diff --git a/guava-tests/benchmark/com/google/common/util/concurrent/FuturesGetCheckedBenchmark.java b/guava-tests/benchmark/com/google/common/util/concurrent/FuturesGetCheckedBenchmark.java
index dd1883bcb053..98b696b4b4bb 100644
--- a/guava-tests/benchmark/com/google/common/util/concurrent/FuturesGetCheckedBenchmark.java
+++ b/guava-tests/benchmark/com/google/common/util/concurrent/FuturesGetCheckedBenchmark.java
@@ -34,7 +34,7 @@
 import java.io.IOException;
 import java.net.URISyntaxException;
 import java.security.GeneralSecurityException;
-import java.security.acl.NotOwnerException;
+import java.security.KeyException;
 import java.util.List;
 import java.util.TooManyListenersException;
 import java.util.concurrent.BrokenBarrierException;
@@ -52,7 +52,8 @@ private enum Validator {
     NON_CACHING_WITH_CONSTRUCTOR_CHECK(nonCachingWithConstructorCheckValidator()),
     NON_CACHING_WITHOUT_CONSTRUCTOR_CHECK(nonCachingWithoutConstructorCheckValidator()),
     WEAK_SET(weakSetValidator()),
-    CLASS_VALUE(classValueValidator());
+    CLASS_VALUE(classValueValidator()),
+    ;
 
     final GetCheckedTypeValidator validator;
 
@@ -92,7 +93,7 @@ private enum ExceptionType {
           ExecutionException.class,
           GeneralSecurityException.class,
           InvalidPreferencesFormatException.class,
-          NotOwnerException.class,
+          KeyException.class,
           RefreshFailedException.class,
           TimeoutException.class,
           TooManyListenersException.class,
diff --git a/guava-tests/benchmark/com/google/common/util/concurrent/MonitorBasedArrayBlockingQueue.java b/guava-tests/benchmark/com/google/common/util/concurrent/MonitorBasedArrayBlockingQueue.java
index c1e5201d788c..dafb39b6f03f 100644
--- a/guava-tests/benchmark/com/google/common/util/concurrent/MonitorBasedArrayBlockingQueue.java
+++ b/guava-tests/benchmark/com/google/common/util/concurrent/MonitorBasedArrayBlockingQueue.java
@@ -36,12 +36,12 @@
  *
  * <p>This is a classic &quot;bounded buffer&quot;, in which a fixed-sized array holds elements
  * inserted by producers and extracted by consumers. Once created, the capacity cannot be increased.
- * Attempts to <tt>put</tt> an element into a full queue will result in the operation blocking;
- * attempts to <tt>take</tt> an element from an empty queue will similarly block.
+ * Attempts to {@code put} an element into a full queue will result in the operation blocking;
+ * attempts to {@code take} an element from an empty queue will similarly block.
  *
  * <p>This class supports an optional fairness policy for ordering waiting producer and consumer
  * threads. By default, this ordering is not guaranteed. However, a queue constructed with fairness
- * set to <tt>true</tt> grants threads access in FIFO order. Fairness generally decreases throughput
+ * set to {@code true} grants threads access in FIFO order. Fairness generally decreases throughput
  * but reduces variability and avoids starvation.
  *
  * <p>This class and its iterator implement all of the <em>optional</em> methods of the {@link
@@ -139,24 +139,24 @@ void removeAt(int i) {
   }
 
   /**
-   * Creates an <tt>MonitorBasedArrayBlockingQueue</tt> with the given (fixed) capacity and default
+   * Creates an {@code MonitorBasedArrayBlockingQueue} with the given (fixed) capacity and default
    * access policy.
    *
    * @param capacity the capacity of this queue
-   * @throws IllegalArgumentException if <tt>capacity</tt> is less than 1
+   * @throws IllegalArgumentException if {@code capacity} is less than 1
    */
   public MonitorBasedArrayBlockingQueue(int capacity) {
     this(capacity, false);
   }
 
   /**
-   * Creates an <tt>MonitorBasedArrayBlockingQueue</tt> with the given (fixed) capacity and the
+   * Creates an {@code MonitorBasedArrayBlockingQueue} with the given (fixed) capacity and the
    * specified access policy.
    *
    * @param capacity the capacity of this queue
-   * @param fair if <tt>true</tt> then queue accesses for threads blocked on insertion or removal,
-   *     are processed in FIFO order; if <tt>false</tt> the access order is unspecified.
-   * @throws IllegalArgumentException if <tt>capacity</tt> is less than 1
+   * @param fair if {@code true} then queue accesses for threads blocked on insertion or removal,
+   *     are processed in FIFO order; if {@code false} the access order is unspecified.
+   * @throws IllegalArgumentException if {@code capacity} is less than 1
    */
   public MonitorBasedArrayBlockingQueue(int capacity, boolean fair) {
     if (capacity <= 0) throw new IllegalArgumentException();
@@ -179,15 +179,15 @@ public boolean isSatisfied() {
   }
 
   /**
-   * Creates an <tt>MonitorBasedArrayBlockingQueue</tt> with the given (fixed) capacity, the
+   * Creates an {@code MonitorBasedArrayBlockingQueue} with the given (fixed) capacity, the
    * specified access policy and initially containing the elements of the given collection, added in
    * traversal order of the collection's iterator.
    *
    * @param capacity the capacity of this queue
-   * @param fair if <tt>true</tt> then queue accesses for threads blocked on insertion or removal,
-   *     are processed in FIFO order; if <tt>false</tt> the access order is unspecified.
+   * @param fair if {@code true} then queue accesses for threads blocked on insertion or removal,
+   *     are processed in FIFO order; if {@code false} the access order is unspecified.
    * @param c the collection of elements to initially contain
-   * @throws IllegalArgumentException if <tt>capacity</tt> is less than <tt>c.size()</tt>, or less
+   * @throws IllegalArgumentException if {@code capacity} is less than {@code c.size()}, or less
    *     than 1.
    * @throws NullPointerException if the specified collection or any of its elements are null
    */
@@ -205,11 +205,11 @@ private static <E> E[] newEArray(int capacity) {
 
   /**
    * Inserts the specified element at the tail of this queue if it is possible to do so immediately
-   * without exceeding the queue's capacity, returning <tt>true</tt> upon success and throwing an
-   * <tt>IllegalStateException</tt> if this queue is full.
+   * without exceeding the queue's capacity, returning {@code true} upon success and throwing an
+   * {@code IllegalStateException} if this queue is full.
    *
    * @param e the element to add
-   * @return <tt>true</tt> (as specified by {@link Collection#add})
+   * @return {@code true} (as specified by {@link Collection#add})
    * @throws IllegalStateException if this queue is full
    * @throws NullPointerException if the specified element is null
    */
@@ -220,7 +220,7 @@ public boolean add(E e) {
 
   /**
    * Inserts the specified element at the tail of this queue if it is possible to do so immediately
-   * without exceeding the queue's capacity, returning <tt>true</tt> upon success and <tt>false</tt>
+   * without exceeding the queue's capacity, returning {@code true} upon success and {@code false}
    * if this queue is full. This method is generally preferable to method {@link #add}, which can
    * fail to insert an element only by throwing an exception.
    *
@@ -361,11 +361,11 @@ public int size() {
   /**
    * Returns the number of additional elements that this queue can ideally (in the absence of memory
    * or resource constraints) accept without blocking. This is always equal to the initial capacity
-   * of this queue less the current <tt>size</tt> of this queue.
+   * of this queue less the current {@code size} of this queue.
    *
    * <p>Note that you <em>cannot</em> always tell if an attempt to insert an element will succeed by
-   * inspecting <tt>remainingCapacity</tt> because it may be the case that another thread is about
-   * to insert or remove an element.
+   * inspecting {@code remainingCapacity} because it may be the case that another thread is about to
+   * insert or remove an element.
    */
   @Override
   public int remainingCapacity() {
@@ -380,12 +380,12 @@ public int remainingCapacity() {
 
   /**
    * Removes a single instance of the specified element from this queue, if it is present. More
-   * formally, removes an element <tt>e</tt> such that <tt>o.equals(e)</tt>, if this queue contains
-   * one or more such elements. Returns <tt>true</tt> if this queue contained the specified element
+   * formally, removes an element {@code e} such that {@code o.equals(e)}, if this queue contains
+   * one or more such elements. Returns {@code true} if this queue contained the specified element
    * (or equivalently, if this queue changed as a result of the call).
    *
    * @param o element to be removed from this queue, if present
-   * @return <tt>true</tt> if this queue changed as a result of the call
+   * @return {@code true} if this queue changed as a result of the call
    */
   @Override
   public boolean remove(@Nullable Object o) {
@@ -410,12 +410,12 @@ public boolean remove(@Nullable Object o) {
   }
 
   /**
-   * Returns <tt>true</tt> if this queue contains the specified element. More formally, returns
-   * <tt>true</tt> if and only if this queue contains at least one element <tt>e</tt> such that
-   * <tt>o.equals(e)</tt>.
+   * Returns {@code true} if this queue contains the specified element. More formally, returns
+   * {@code true} if and only if this queue contains at least one element {@code e} such that {@code
+   * o.equals(e)}.
    *
    * @param o object to be checked for containment in this queue
-   * @return <tt>true</tt> if this queue contains the specified element
+   * @return {@code true} if this queue contains the specified element
    */
   @Override
   public boolean contains(@Nullable Object o) {
@@ -474,19 +474,19 @@ public Object[] toArray() {
    *
    * <p>If this queue fits in the specified array with room to spare (i.e., the array has more
    * elements than this queue), the element in the array immediately following the end of the queue
-   * is set to <tt>null</tt>.
+   * is set to {@code null}.
    *
    * <p>Like the {@link #toArray()} method, this method acts as bridge between array-based and
    * collection-based APIs. Further, this method allows precise control over the runtime type of the
    * output array, and may, under certain circumstances, be used to save allocation costs.
    *
-   * <p>Suppose <tt>x</tt> is a queue known to contain only strings. The following code can be used
-   * to dump the queue into a newly allocated array of <tt>String</tt>:
+   * <p>Suppose {@code x} is a queue known to contain only strings. The following code can be used
+   * to dump the queue into a newly allocated array of {@code String}:
    *
    * <pre>
    *     String[] y = x.toArray(new String[0]);</pre>
    *
-   * <p>Note that <tt>toArray(new Object[0])</tt> is identical in function to <tt>toArray()</tt>.
+   * <p>Note that {@code toArray(new Object[0])} is identical in function to {@code toArray()}.
    *
    * @param a the array into which the elements of the queue are to be stored, if it is big enough;
    *     otherwise, a new array of the same runtime type is allocated for this purpose
@@ -626,8 +626,8 @@ public int drainTo(Collection<? super E> c, int maxElements) {
   }
 
   /**
-   * Returns an iterator over the elements in this queue in proper sequence. The returned
-   * <tt>Iterator</tt> is a "weakly consistent" iterator that will never throw {@link
+   * Returns an iterator over the elements in this queue in proper sequence. The returned {@code
+   * Iterator} is a "weakly consistent" iterator that will never throw {@link
    * ConcurrentModificationException}, and guarantees to traverse elements as they existed upon
    * construction of the iterator, and may (but is not guaranteed to) reflect any modifications
    * subsequent to construction.
diff --git a/guava-tests/benchmark/com/google/common/util/concurrent/MonitorBasedPriorityBlockingQueue.java b/guava-tests/benchmark/com/google/common/util/concurrent/MonitorBasedPriorityBlockingQueue.java
index 6e063466be0a..16b648b8680a 100644
--- a/guava-tests/benchmark/com/google/common/util/concurrent/MonitorBasedPriorityBlockingQueue.java
+++ b/guava-tests/benchmark/com/google/common/util/concurrent/MonitorBasedPriorityBlockingQueue.java
@@ -35,23 +35,23 @@
 /**
  * An unbounded {@linkplain BlockingQueue blocking queue} that uses the same ordering rules as class
  * {@link PriorityQueue} and supplies blocking retrieval operations. While this queue is logically
- * unbounded, attempted additions may fail due to resource exhaustion (causing
- * <tt>OutOfMemoryError</tt>). This class does not permit <tt>null</tt> elements. A priority queue
- * relying on {@linkplain Comparable natural ordering} also does not permit insertion of
- * non-comparable objects (doing so results in <tt>ClassCastException</tt>).
+ * unbounded, attempted additions may fail due to resource exhaustion (causing {@code
+ * OutOfMemoryError}). This class does not permit {@code null} elements. A priority queue relying on
+ * {@linkplain Comparable natural ordering} also does not permit insertion of non-comparable objects
+ * (doing so results in {@code ClassCastException}).
  *
  * <p>This class and its iterator implement all of the <em>optional</em> methods of the {@link
  * Collection} and {@link Iterator} interfaces. The Iterator provided in method {@link #iterator()}
  * is <em>not</em> guaranteed to traverse the elements of the MonitorBasedPriorityBlockingQueue in
- * any particular order. If you need ordered traversal, consider using
- * <tt>Arrays.sort(pq.toArray())</tt>. Also, method <tt>drainTo</tt> can be used to <em>remove</em>
- * some or all elements in priority order and place them in another collection.
+ * any particular order. If you need ordered traversal, consider using {@code
+ * Arrays.sort(pq.toArray())}. Also, method {@code drainTo} can be used to <em>remove</em> some or
+ * all elements in priority order and place them in another collection.
  *
  * <p>Operations on this class make no guarantees about the ordering of elements with equal
  * priority. If you need to enforce an ordering, you can define custom classes or comparators that
  * use a secondary key to break ties in primary priority values. For example, here is a class that
  * applies first-in-first-out tie-breaking to comparable elements. To use it, you would insert a
- * <tt>new FIFOEntry(anEntry)</tt> instead of a plain entry object.
+ * {@code new FIFOEntry(anEntry)} instead of a plain entry object.
  *
  * <pre>
  * class FIFOEntry&lt;E extends Comparable&lt;? super E&gt;&gt;
@@ -96,32 +96,32 @@ public boolean isSatisfied() {
       };
 
   /**
-   * Creates a <tt>MonitorBasedPriorityBlockingQueue</tt> with the default initial capacity (11)
-   * that orders its elements according to their {@linkplain Comparable natural ordering}.
+   * Creates a {@code MonitorBasedPriorityBlockingQueue} with the default initial capacity (11) that
+   * orders its elements according to their {@linkplain Comparable natural ordering}.
    */
   public MonitorBasedPriorityBlockingQueue() {
     q = new PriorityQueue<E>();
   }
 
   /**
-   * Creates a <tt>MonitorBasedPriorityBlockingQueue</tt> with the specified initial capacity that
+   * Creates a {@code MonitorBasedPriorityBlockingQueue} with the specified initial capacity that
    * orders its elements according to their {@linkplain Comparable natural ordering}.
    *
    * @param initialCapacity the initial capacity for this priority queue
-   * @throws IllegalArgumentException if <tt>initialCapacity</tt> is less than 1
+   * @throws IllegalArgumentException if {@code initialCapacity} is less than 1
    */
   public MonitorBasedPriorityBlockingQueue(int initialCapacity) {
     q = new PriorityQueue<E>(initialCapacity, null);
   }
 
   /**
-   * Creates a <tt>MonitorBasedPriorityBlockingQueue</tt> with the specified initial capacity that
+   * Creates a {@code MonitorBasedPriorityBlockingQueue} with the specified initial capacity that
    * orders its elements according to the specified comparator.
    *
    * @param initialCapacity the initial capacity for this priority queue
    * @param comparator the comparator that will be used to order this priority queue. If {@code
    *     null}, the {@linkplain Comparable natural ordering} of the elements will be used.
-   * @throws IllegalArgumentException if <tt>initialCapacity</tt> is less than 1
+   * @throws IllegalArgumentException if {@code initialCapacity} is less than 1
    */
   public MonitorBasedPriorityBlockingQueue(
       int initialCapacity, @Nullable Comparator<? super E> comparator) {
@@ -129,7 +129,7 @@ public MonitorBasedPriorityBlockingQueue(
   }
 
   /**
-   * Creates a <tt>MonitorBasedPriorityBlockingQueue</tt> containing the elements in the specified
+   * Creates a {@code MonitorBasedPriorityBlockingQueue} containing the elements in the specified
    * collection. If the specified collection is a {@link SortedSet} or a {@link PriorityQueue}, this
    * priority queue will be ordered according to the same ordering. Otherwise, this priority queue
    * will be ordered according to the {@linkplain Comparable natural ordering} of its elements.
@@ -147,7 +147,7 @@ public MonitorBasedPriorityBlockingQueue(Collection<? extends E> c) {
    * Inserts the specified element into this priority queue.
    *
    * @param e the element to add
-   * @return <tt>true</tt> (as specified by {@link Collection#add})
+   * @return {@code true} (as specified by {@link Collection#add})
    * @throws ClassCastException if the specified element cannot be compared with elements currently
    *     in the priority queue according to the priority queue's ordering
    * @throws NullPointerException if the specified element is null
@@ -161,7 +161,7 @@ public boolean add(E e) {
    * Inserts the specified element into this priority queue.
    *
    * @param e the element to add
-   * @return <tt>true</tt> (as specified by {@link Queue#offer})
+   * @return {@code true} (as specified by {@link Queue#offer})
    * @throws ClassCastException if the specified element cannot be compared with elements currently
    *     in the priority queue according to the priority queue's ordering
    * @throws NullPointerException if the specified element is null
@@ -188,7 +188,7 @@ public boolean offer(E e) {
    * @param e the element to add
    * @param timeout This parameter is ignored as the method never blocks
    * @param unit This parameter is ignored as the method never blocks
-   * @return <tt>true</tt>
+   * @return {@code true}
    * @throws ClassCastException if the specified element cannot be compared with elements currently
    *     in the priority queue according to the priority queue's ordering
    * @throws NullPointerException if the specified element is null
@@ -261,10 +261,10 @@ public E peek() {
   }
 
   /**
-   * Returns the comparator used to order the elements in this queue, or <tt>null</tt> if this queue
+   * Returns the comparator used to order the elements in this queue, or {@code null} if this queue
    * uses the {@linkplain Comparable natural ordering} of its elements.
    *
-   * @return the comparator used to order the elements in this queue, or <tt>null</tt> if this queue
+   * @return the comparator used to order the elements in this queue, or {@code null} if this queue
    *     uses the natural ordering of its elements
    */
   public Comparator<? super E> comparator() {
@@ -283,10 +283,10 @@ public int size() {
   }
 
   /**
-   * Always returns <tt>Integer.MAX_VALUE</tt> because a <tt>MonitorBasedPriorityBlockingQueue</tt>
-   * is not capacity constrained.
+   * Always returns {@code Integer.MAX_VALUE} because a {@code MonitorBasedPriorityBlockingQueue} is
+   * not capacity constrained.
    *
-   * @return <tt>Integer.MAX_VALUE</tt>
+   * @return {@code Integer.MAX_VALUE}
    */
   @Override
   public int remainingCapacity() {
@@ -300,7 +300,7 @@ public int remainingCapacity() {
    * specified element (or equivalently, if this queue changed as a result of the call).
    *
    * @param o element to be removed from this queue, if present
-   * @return <tt>true</tt> if this queue changed as a result of the call
+   * @return {@code true} if this queue changed as a result of the call
    */
   @Override
   public boolean remove(@Nullable Object o) {
@@ -319,7 +319,7 @@ public boolean remove(@Nullable Object o) {
    * o.equals(e)}.
    *
    * @param o object to be checked for containment in this queue
-   * @return <tt>true</tt> if this queue contains the specified element
+   * @return {@code true} if this queue contains the specified element
    */
   @Override
   public boolean contains(@Nullable Object o) {
@@ -363,19 +363,19 @@ public Object[] toArray() {
    *
    * <p>If this queue fits in the specified array with room to spare (i.e., the array has more
    * elements than this queue), the element in the array immediately following the end of the queue
-   * is set to <tt>null</tt>.
+   * is set to {@code null}.
    *
    * <p>Like the {@link #toArray()} method, this method acts as bridge between array-based and
    * collection-based APIs. Further, this method allows precise control over the runtime type of the
    * output array, and may, under certain circumstances, be used to save allocation costs.
    *
-   * <p>Suppose <tt>x</tt> is a queue known to contain only strings. The following code can be used
-   * to dump the queue into a newly allocated array of <tt>String</tt>:
+   * <p>Suppose {@code x} is a queue known to contain only strings. The following code can be used
+   * to dump the queue into a newly allocated array of {@code String}:
    *
    * <pre>
    *     String[] y = x.toArray(new String[0]);</pre>
    *
-   * <p>Note that <tt>toArray(new Object[0])</tt> is identical in function to <tt>toArray()</tt>.
+   * <p>Note that {@code toArray(new Object[0])} is identical in function to {@code toArray()}.
    *
    * @param a the array into which the elements of the queue are to be stored, if it is big enough;
    *     otherwise, a new array of the same runtime type is allocated for this purpose
@@ -474,7 +474,7 @@ public void clear() {
 
   /**
    * Returns an iterator over the elements in this queue. The iterator does not return the elements
-   * in any particular order. The returned <tt>Iterator</tt> is a "weakly consistent" iterator that
+   * in any particular order. The returned {@code Iterator} is a "weakly consistent" iterator that
    * will never throw {@link ConcurrentModificationException}, and guarantees to traverse elements
    * as they existed upon construction of the iterator, and may (but is not guaranteed to) reflect
    * any modifications subsequent to construction.
diff --git a/guava-tests/pom.xml b/guava-tests/pom.xml
index 8cfcad5a7b24..b7728d8b1b13 100644
--- a/guava-tests/pom.xml
+++ b/guava-tests/pom.xml
@@ -5,7 +5,7 @@
   <parent>
     <groupId>com.google.guava</groupId>
     <artifactId>guava-parent</artifactId>
-    <version>30.1.1-jre</version>
+    <version>31.1-jre</version>
   </parent>
   <artifactId>guava-tests</artifactId>
   <name>Guava Unit Tests</name>
@@ -106,6 +106,9 @@
       <plugin>
         <groupId>org.codehaus.mojo</groupId>
         <artifactId>animal-sniffer-maven-plugin</artifactId>
+        <configuration>
+          <checkTestClasses>false</checkTestClasses> <!-- TODO(cpovirk): Consider checking them. -->
+        </configuration>
       </plugin>
       <plugin>
         <groupId>org.codehaus.mojo</groupId>
diff --git a/guava-tests/test/com/google/common/base/AbstractIteratorTest.java b/guava-tests/test/com/google/common/base/AbstractIteratorTest.java
index da732bf54946..ddb7d709739a 100644
--- a/guava-tests/test/com/google/common/base/AbstractIteratorTest.java
+++ b/guava-tests/test/com/google/common/base/AbstractIteratorTest.java
@@ -205,7 +205,7 @@ protected Integer computeNext() {
   // hasNext/next), but we'll cop out for now, knowing that
   // next() both start by invoking hasNext() anyway.
 
-  /** Throws a undeclared checked exception. */
+  /** Throws an undeclared checked exception. */
   private static void sneakyThrow(Throwable t) {
     class SneakyThrower<T extends Throwable> {
       @SuppressWarnings("unchecked") // intentionally unsafe for test
diff --git a/guava-tests/test/com/google/common/base/AsciiTest.java b/guava-tests/test/com/google/common/base/AsciiTest.java
index d3a1f8f6597e..9e6b0e41ab86 100644
--- a/guava-tests/test/com/google/common/base/AsciiTest.java
+++ b/guava-tests/test/com/google/common/base/AsciiTest.java
@@ -54,8 +54,8 @@ public void testToUpperCase() {
   public void testCharsIgnored() {
     for (char c : IGNORED.toCharArray()) {
       String str = String.valueOf(c);
-      assertTrue(str, c == Ascii.toLowerCase(c));
-      assertTrue(str, c == Ascii.toUpperCase(c));
+      assertEquals(str, c, Ascii.toLowerCase(c));
+      assertEquals(str, c, Ascii.toUpperCase(c));
       assertFalse(str, Ascii.isLowerCase(c));
       assertFalse(str, Ascii.isUpperCase(c));
     }
@@ -98,27 +98,26 @@ public void testTruncate() {
   }
 
   public void testTruncateIllegalArguments() {
-    String truncated = null;
     try {
-      truncated = Ascii.truncate("foobar", 2, "...");
+      Ascii.truncate("foobar", 2, "...");
       fail();
     } catch (IllegalArgumentException expected) {
     }
 
     try {
-      truncated = Ascii.truncate("foobar", 8, "1234567890");
+      Ascii.truncate("foobar", 8, "1234567890");
       fail();
     } catch (IllegalArgumentException expected) {
     }
 
     try {
-      truncated = Ascii.truncate("foobar", -1, "...");
+      Ascii.truncate("foobar", -1, "...");
       fail();
     } catch (IllegalArgumentException expected) {
     }
 
     try {
-      truncated = Ascii.truncate("foobar", -1, "");
+      Ascii.truncate("foobar", -1, "");
       fail();
     } catch (IllegalArgumentException expected) {
     }
diff --git a/guava-tests/test/com/google/common/base/CharMatcherTest.java b/guava-tests/test/com/google/common/base/CharMatcherTest.java
index 5412882c5641..49bdbbaffe25 100644
--- a/guava-tests/test/com/google/common/base/CharMatcherTest.java
+++ b/guava-tests/test/com/google/common/base/CharMatcherTest.java
@@ -386,7 +386,7 @@ private void reallyTestOneCharNoMatch(CharMatcher matcher, String s) {
     assertSame(s, matcher.replaceFrom(s, 'z'));
     assertSame(s, matcher.replaceFrom(s, "ZZ"));
     assertSame(s, matcher.trimFrom(s));
-    assertSame(0, matcher.countIn(s));
+    assertEquals(0, matcher.countIn(s));
   }
 
   private void reallyTestMatchThenNoMatch(CharMatcher matcher, String s) {
diff --git a/guava-tests/test/com/google/common/base/OptionalTest.java b/guava-tests/test/com/google/common/base/OptionalTest.java
index df0c483513d4..47609ae00183 100644
--- a/guava-tests/test/com/google/common/base/OptionalTest.java
+++ b/guava-tests/test/com/google/common/base/OptionalTest.java
@@ -85,6 +85,7 @@ public void testIsPresent_no() {
     assertFalse(Optional.absent().isPresent());
   }
 
+  @SuppressWarnings("OptionalOfRedundantMethod") // Unit tests for Optional
   public void testIsPresent_yes() {
     assertTrue(Optional.of("training").isPresent());
   }
@@ -102,6 +103,7 @@ public void testGet_present() {
     assertEquals("training", Optional.of("training").get());
   }
 
+  @SuppressWarnings("OptionalOfRedundantMethod") // Unit tests for Optional
   public void testOr_T_present() {
     assertEquals("a", Optional.of("a").or("default"));
   }
@@ -110,6 +112,7 @@ public void testOr_T_absent() {
     assertEquals("default", Optional.absent().or("default"));
   }
 
+  @SuppressWarnings("OptionalOfRedundantMethod") // Unit tests for Optional
   public void testOr_supplier_present() {
     assertEquals("a", Optional.of("a").or(Suppliers.ofInstance("fallback")));
   }
@@ -128,11 +131,13 @@ public void testOr_nullSupplier_absent() {
     }
   }
 
+  @SuppressWarnings("OptionalOfRedundantMethod") // Unit tests for Optional
   public void testOr_nullSupplier_present() {
     Supplier<String> nullSupplier = Suppliers.ofInstance(null);
     assertEquals("a", Optional.of("a").or(nullSupplier));
   }
 
+  @SuppressWarnings("OptionalOfRedundantMethod") // Unit tests for Optional
   public void testOr_Optional_present() {
     assertEquals(Optional.of("a"), Optional.of("a").or(Optional.of("fallback")));
   }
@@ -141,6 +146,7 @@ public void testOr_Optional_absent() {
     assertEquals(Optional.of("fallback"), Optional.absent().or(Optional.of("fallback")));
   }
 
+  @SuppressWarnings("OptionalOfRedundantMethod") // Unit tests for Optional
   public void testOrNull_present() {
     assertEquals("a", Optional.of("a").orNull());
   }
diff --git a/guava-tests/test/com/google/common/base/PreconditionsTest.java b/guava-tests/test/com/google/common/base/PreconditionsTest.java
index 072649f99da1..1add44d32386 100644
--- a/guava-tests/test/com/google/common/base/PreconditionsTest.java
+++ b/guava-tests/test/com/google/common/base/PreconditionsTest.java
@@ -24,7 +24,6 @@
 import com.google.common.collect.ImmutableSet;
 import com.google.common.collect.Lists;
 import com.google.common.testing.ArbitraryInstances;
-import com.google.common.testing.NullPointerTester;
 import java.lang.reflect.InvocationTargetException;
 import java.lang.reflect.Method;
 import java.util.ArrayList;
@@ -539,8 +538,22 @@ public void overloadSelection() {
 
   @GwtIncompatible // NullPointerTester
   public void testNullPointers() {
-    NullPointerTester tester = new NullPointerTester();
-    tester.testAllPublicStaticMethods(Preconditions.class);
+    /*
+     * Don't bother testing: Preconditions defines a bunch of methods that accept a template (or
+     * even entire message) that simultaneously:
+     *
+     * - _shouldn't_ be null, so we don't annotate it with @Nullable
+     *
+     * - _can_ be null without causing a runtime failure (because we don't want the interesting
+     *   details of precondition failure to be hidden by an exception we throw about an unexpectedly
+     *   null _failure message_)
+     *
+     * That combination upsets NullPointerTester, which wants any call that passes null for a
+     * non-@Nullable parameter to trigger a NullPointerException.
+     *
+     * (We still define this empty method to keep PackageSanityTests from generating its own
+     * automated nullness tests, which would fail.)
+     */
   }
 
   private static final Object IGNORE_ME =
diff --git a/guava-tests/test/com/google/common/base/StopwatchJavaTimeTest.java b/guava-tests/test/com/google/common/base/StopwatchJavaTimeTest.java
new file mode 100644
index 000000000000..35fd5b10895f
--- /dev/null
+++ b/guava-tests/test/com/google/common/base/StopwatchJavaTimeTest.java
@@ -0,0 +1,37 @@
+/*
+ * Copyright (C) 2008 The Guava Authors
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package com.google.common.base;
+
+import com.google.common.annotations.GwtIncompatible;
+import com.google.common.testing.FakeTicker;
+import java.time.Duration;
+import junit.framework.TestCase;
+
+/** Unit test for the {@code java.time} support in {@link Stopwatch}. */
+@GwtIncompatible
+public class StopwatchJavaTimeTest extends TestCase {
+  private final FakeTicker ticker = new FakeTicker();
+  private final Stopwatch stopwatch = new Stopwatch(ticker);
+
+  public void testElapsed_duration() {
+    stopwatch.start();
+    ticker.advance(999999);
+    assertEquals(Duration.ofNanos(999999), stopwatch.elapsed());
+    ticker.advance(1);
+    assertEquals(Duration.ofMillis(1), stopwatch.elapsed());
+  }
+}
diff --git a/guava-tests/test/com/google/common/base/StopwatchTest.java b/guava-tests/test/com/google/common/base/StopwatchTest.java
index 25ba527b7061..b85ebb7b0e94 100644
--- a/guava-tests/test/com/google/common/base/StopwatchTest.java
+++ b/guava-tests/test/com/google/common/base/StopwatchTest.java
@@ -21,9 +21,7 @@
 import static java.util.concurrent.TimeUnit.NANOSECONDS;
 
 import com.google.common.annotations.GwtCompatible;
-import com.google.common.annotations.GwtIncompatible;
 import com.google.common.testing.FakeTicker;
-import java.time.Duration;
 import junit.framework.TestCase;
 
 /**
@@ -168,15 +166,6 @@ public void testElapsed_millis() {
     assertEquals(1, stopwatch.elapsed(MILLISECONDS));
   }
 
-  @GwtIncompatible
-  public void testElapsed_duration() {
-    stopwatch.start();
-    ticker.advance(999999);
-    assertEquals(Duration.ofNanos(999999), stopwatch.elapsed());
-    ticker.advance(1);
-    assertEquals(Duration.ofMillis(1), stopwatch.elapsed());
-  }
-
   public void testToString() {
     stopwatch.start();
     assertEquals("0.000 ns", stopwatch.toString());
diff --git a/guava-tests/test/com/google/common/base/ToStringHelperTest.java b/guava-tests/test/com/google/common/base/ToStringHelperTest.java
index 3f1ef0f9e829..db15f2ef811c 100644
--- a/guava-tests/test/com/google/common/base/ToStringHelperTest.java
+++ b/guava-tests/test/com/google/common/base/ToStringHelperTest.java
@@ -116,15 +116,15 @@ class LocalInnerNestedClass {}
   @GwtIncompatible // Class names are obfuscated in GWT
   public void testToStringHelper_moreThanNineAnonymousClasses() {
     // The nth anonymous class has a name ending like "Outer.$n"
-    Object o1 = new Object() {};
-    Object o2 = new Object() {};
-    Object o3 = new Object() {};
-    Object o4 = new Object() {};
-    Object o5 = new Object() {};
-    Object o6 = new Object() {};
-    Object o7 = new Object() {};
-    Object o8 = new Object() {};
-    Object o9 = new Object() {};
+    Object unused1 = new Object() {};
+    Object unused2 = new Object() {};
+    Object unused3 = new Object() {};
+    Object unused4 = new Object() {};
+    Object unused5 = new Object() {};
+    Object unused6 = new Object() {};
+    Object unused7 = new Object() {};
+    Object unused8 = new Object() {};
+    Object unused9 = new Object() {};
     Object o10 = new Object() {};
     String toTest = MoreObjects.toStringHelper(o10).toString();
     assertEquals("{}", toTest);
@@ -132,15 +132,15 @@ public void testToStringHelper_moreThanNineAnonymousClasses() {
 
   public void testToStringHelperLenient_moreThanNineAnonymousClasses() {
     // The nth anonymous class has a name ending like "Outer.$n"
-    Object o1 = new Object() {};
-    Object o2 = new Object() {};
-    Object o3 = new Object() {};
-    Object o4 = new Object() {};
-    Object o5 = new Object() {};
-    Object o6 = new Object() {};
-    Object o7 = new Object() {};
-    Object o8 = new Object() {};
-    Object o9 = new Object() {};
+    Object unused1 = new Object() {};
+    Object unused2 = new Object() {};
+    Object unused3 = new Object() {};
+    Object unused4 = new Object() {};
+    Object unused5 = new Object() {};
+    Object unused6 = new Object() {};
+    Object unused7 = new Object() {};
+    Object unused8 = new Object() {};
+    Object unused9 = new Object() {};
     Object o10 = new Object() {};
     String toTest = MoreObjects.toStringHelper(o10).toString();
     assertTrue(toTest, toTest.matches(".*\\{\\}"));
@@ -357,7 +357,7 @@ public void testToStringOmitNullValues_manyFieldsLastNull() {
   }
 
   @GwtIncompatible // Class names are obfuscated in GWT
-  public void testToStringOmitNullValues_oneValue() {
+  public void testToStringOmitEmptyValues_oneValue() {
     String toTest =
         MoreObjects.toStringHelper(new TestClass()).omitNullValues().addValue(null).toString();
     assertEquals("TestClass{}", toTest);
diff --git a/guava-tests/test/com/google/common/base/VerifyTest.java b/guava-tests/test/com/google/common/base/VerifyTest.java
index 03d2c2ff4a28..37c6efc1a990 100644
--- a/guava-tests/test/com/google/common/base/VerifyTest.java
+++ b/guava-tests/test/com/google/common/base/VerifyTest.java
@@ -19,11 +19,12 @@
 import static com.google.common.truth.Truth.assertThat;
 
 import com.google.common.annotations.GwtCompatible;
+import com.google.common.annotations.GwtIncompatible;
 import junit.framework.AssertionFailedError;
 import junit.framework.TestCase;
 
 /** Unit test for {@link com.google.common.base.Verify}. */
-@GwtCompatible
+@GwtCompatible(emulated = true)
 public class VerifyTest extends TestCase {
   public void testVerify_simple_success() {
     verify(true);
@@ -92,6 +93,11 @@ public void testVerifyNotNull_simpleMessage_failure() {
     }
   }
 
+  @GwtIncompatible // NullPointerTester
+  public void testNullPointers() {
+    // Don't bother testing: Verify is like Preconditions. See the discussion on that class.
+  }
+
   private static final Object IGNORE_ME =
       new Object() {
         @Override
diff --git a/guava-tests/test/com/google/common/cache/LocalCacheTest.java b/guava-tests/test/com/google/common/cache/LocalCacheTest.java
index ceecb5d73bf5..db3b80015169 100644
--- a/guava-tests/test/com/google/common/cache/LocalCacheTest.java
+++ b/guava-tests/test/com/google/common/cache/LocalCacheTest.java
@@ -229,7 +229,7 @@ public void tearDown() throws Exception {
 
   private Throwable popLoggedThrowable() {
     List<LogRecord> logRecords = logHandler.getStoredLogRecords();
-    assertSame(1, logRecords.size());
+    assertEquals(1, logRecords.size());
     LogRecord logRecord = logRecords.get(0);
     logHandler.clear();
     return logRecord.getThrown();
diff --git a/guava-tests/test/com/google/common/collect/AbstractIteratorTest.java b/guava-tests/test/com/google/common/collect/AbstractIteratorTest.java
index 35922105f196..a76907cda7c7 100644
--- a/guava-tests/test/com/google/common/collect/AbstractIteratorTest.java
+++ b/guava-tests/test/com/google/common/collect/AbstractIteratorTest.java
@@ -250,6 +250,7 @@ public Integer computeNext() {
     }
   }
 
+  @SuppressWarnings("DoNotCall")
   public void testCantRemove() {
     Iterator<Integer> iter =
         new AbstractIterator<Integer>() {
diff --git a/guava-tests/test/com/google/common/collect/AbstractMapEntryTest.java b/guava-tests/test/com/google/common/collect/AbstractMapEntryTest.java
index 11c66a702375..63c17dedaeca 100644
--- a/guava-tests/test/com/google/common/collect/AbstractMapEntryTest.java
+++ b/guava-tests/test/com/google/common/collect/AbstractMapEntryTest.java
@@ -61,7 +61,8 @@ public void testToStringNull() {
 
   public void testEquals() {
     Entry<String, Integer> foo1 = entry("foo", 1);
-    assertEquals(foo1, foo1);
+    // Explicitly call `equals`; `assertEquals` might return fast
+    assertTrue(foo1.equals(foo1));
     assertEquals(control("foo", 1), foo1);
     assertEquals(control("bar", 2), entry("bar", 2));
     assertFalse(control("foo", 1).equals(entry("foo", 2)));
diff --git a/guava-tests/test/com/google/common/collect/CompactHashMapFloodingTest.java b/guava-tests/test/com/google/common/collect/CompactHashMapFloodingTest.java
new file mode 100644
index 000000000000..1a03163d224c
--- /dev/null
+++ b/guava-tests/test/com/google/common/collect/CompactHashMapFloodingTest.java
@@ -0,0 +1,28 @@
+/*
+ * Copyright (C) 2012 The Guava Authors
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package com.google.common.collect;
+
+import java.util.Map;
+
+public class CompactHashMapFloodingTest extends AbstractHashFloodingTest<Map<Object, Object>> {
+  public CompactHashMapFloodingTest() {
+    super(
+        ImmutableList.of(Construction.mapFromKeys(CompactHashMap::create)),
+        n -> n * Math.log(n),
+        ImmutableList.of(QueryOp.MAP_GET));
+  }
+}
diff --git a/guava-tests/test/com/google/common/collect/CompactHashMapTest.java b/guava-tests/test/com/google/common/collect/CompactHashMapTest.java
index 095b1c92eced..8e175b47e295 100644
--- a/guava-tests/test/com/google/common/collect/CompactHashMapTest.java
+++ b/guava-tests/test/com/google/common/collect/CompactHashMapTest.java
@@ -82,7 +82,6 @@ protected Map<String, String> create(Entry<String, String>[] entries) {
                 CollectionFeature.SUPPORTS_ITERATOR_REMOVE)
             .createTestSuite());
     suite.addTestSuite(CompactHashMapTest.class);
-    suite.addTestSuite(FloodingTest.class);
     return suite;
   }
 
@@ -141,12 +140,4 @@ public void testAllocArraysExpectedSize() {
     }
   }
 
-  public static class FloodingTest extends AbstractHashFloodingTest<Map<Object, Object>> {
-    public FloodingTest() {
-      super(
-          ImmutableList.of(Construction.mapFromKeys(CompactHashMap::create)),
-          n -> n * Math.log(n),
-          ImmutableList.of(QueryOp.MAP_GET));
-    }
-  }
 }
diff --git a/guava-tests/test/com/google/common/collect/CompactHashSetFloodingTest.java b/guava-tests/test/com/google/common/collect/CompactHashSetFloodingTest.java
new file mode 100644
index 000000000000..53e9a6195ece
--- /dev/null
+++ b/guava-tests/test/com/google/common/collect/CompactHashSetFloodingTest.java
@@ -0,0 +1,28 @@
+/*
+ * Copyright (C) 2012 The Guava Authors
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package com.google.common.collect;
+
+import java.util.Set;
+
+public class CompactHashSetFloodingTest extends AbstractHashFloodingTest<Set<Object>> {
+  public CompactHashSetFloodingTest() {
+    super(
+        ImmutableList.of(Construction.setFromElements(CompactHashSet::create)),
+        n -> n * Math.log(n),
+        ImmutableList.of(QueryOp.SET_CONTAINS));
+  }
+}
diff --git a/guava-tests/test/com/google/common/collect/CompactHashSetTest.java b/guava-tests/test/com/google/common/collect/CompactHashSetTest.java
index 6e2817ba0ba1..f55f8d68a420 100644
--- a/guava-tests/test/com/google/common/collect/CompactHashSetTest.java
+++ b/guava-tests/test/com/google/common/collect/CompactHashSetTest.java
@@ -53,7 +53,6 @@ public static Test suite() {
 
     TestSuite suite = new TestSuite();
     suite.addTestSuite(CompactHashSetTest.class);
-    suite.addTestSuite(FloodingTest.class);
     suite.addTest(
         SetTestSuiteBuilder.using(
                 new TestStringSetGenerator() {
@@ -124,12 +123,4 @@ public void testAllocArraysExpectedSize() {
     }
   }
 
-  public static class FloodingTest extends AbstractHashFloodingTest<Set<Object>> {
-    public FloodingTest() {
-      super(
-          ImmutableList.of(Construction.setFromElements(CompactHashSet::create)),
-          n -> n * Math.log(n),
-          ImmutableList.of(QueryOp.SET_CONTAINS));
-    }
-  }
 }
diff --git a/android/guava/src/com/google/common/util/concurrent/IgnoreJRERequirement.java b/guava-tests/test/com/google/common/collect/CompactLinkedHashMapFloodingTest.java
similarity index 56%
rename from android/guava/src/com/google/common/util/concurrent/IgnoreJRERequirement.java
rename to guava-tests/test/com/google/common/collect/CompactLinkedHashMapFloodingTest.java
index eaaa94f09097..826fc82b7945 100644
--- a/android/guava/src/com/google/common/util/concurrent/IgnoreJRERequirement.java
+++ b/guava-tests/test/com/google/common/collect/CompactLinkedHashMapFloodingTest.java
@@ -1,5 +1,5 @@
 /*
- * Copyright 2019 The Guava Authors
+ * Copyright (C) 2012 The Guava Authors
  *
  * Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file except
  * in compliance with the License. You may obtain a copy of the License at
@@ -12,13 +12,16 @@
  * the License.
  */
 
-package com.google.common.util.concurrent;
+package com.google.common.collect;
 
-import static java.lang.annotation.ElementType.CONSTRUCTOR;
-import static java.lang.annotation.ElementType.METHOD;
-import static java.lang.annotation.ElementType.TYPE;
+import java.util.Map;
 
-import java.lang.annotation.Target;
-
-@Target({METHOD, CONSTRUCTOR, TYPE})
-@interface IgnoreJRERequirement {}
+public class CompactLinkedHashMapFloodingTest
+    extends AbstractHashFloodingTest<Map<Object, Object>> {
+  public CompactLinkedHashMapFloodingTest() {
+    super(
+        ImmutableList.of(Construction.mapFromKeys(CompactLinkedHashMap::create)),
+        n -> n * Math.log(n),
+        ImmutableList.of(QueryOp.MAP_GET));
+  }
+}
diff --git a/guava-tests/test/com/google/common/collect/CompactLinkedHashMapTest.java b/guava-tests/test/com/google/common/collect/CompactLinkedHashMapTest.java
index e8ba94c71485..e2f86113a305 100644
--- a/guava-tests/test/com/google/common/collect/CompactLinkedHashMapTest.java
+++ b/guava-tests/test/com/google/common/collect/CompactLinkedHashMapTest.java
@@ -82,7 +82,6 @@ protected Map<String, String> create(Entry<String, String>[] entries) {
                 CollectionFeature.KNOWN_ORDER)
             .createTestSuite());
     suite.addTestSuite(CompactLinkedHashMapTest.class);
-    suite.addTestSuite(FloodingTest.class);
     return suite;
   }
 
@@ -202,12 +201,4 @@ public void testAllocArraysExpectedSize() {
     }
   }
 
-  public static class FloodingTest extends AbstractHashFloodingTest<Map<Object, Object>> {
-    public FloodingTest() {
-      super(
-          ImmutableList.of(Construction.mapFromKeys(CompactLinkedHashMap::create)),
-          n -> n * Math.log(n),
-          ImmutableList.of(QueryOp.MAP_GET));
-    }
-  }
 }
diff --git a/guava-tests/test/com/google/common/collect/CompactLinkedHashSetFloodingTest.java b/guava-tests/test/com/google/common/collect/CompactLinkedHashSetFloodingTest.java
new file mode 100644
index 000000000000..b8a5d9797d76
--- /dev/null
+++ b/guava-tests/test/com/google/common/collect/CompactLinkedHashSetFloodingTest.java
@@ -0,0 +1,28 @@
+/*
+ * Copyright (C) 2012 The Guava Authors
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package com.google.common.collect;
+
+import java.util.Set;
+
+public class CompactLinkedHashSetFloodingTest extends AbstractHashFloodingTest<Set<Object>> {
+  public CompactLinkedHashSetFloodingTest() {
+    super(
+        ImmutableList.of(Construction.setFromElements(CompactLinkedHashSet::create)),
+        n -> n * Math.log(n),
+        ImmutableList.of(QueryOp.SET_CONTAINS));
+  }
+}
diff --git a/guava-tests/test/com/google/common/collect/CompactLinkedHashSetTest.java b/guava-tests/test/com/google/common/collect/CompactLinkedHashSetTest.java
index dba9a731233f..ee8f408734cf 100644
--- a/guava-tests/test/com/google/common/collect/CompactLinkedHashSetTest.java
+++ b/guava-tests/test/com/google/common/collect/CompactLinkedHashSetTest.java
@@ -54,7 +54,6 @@ public static Test suite() {
 
     TestSuite suite = new TestSuite();
     suite.addTestSuite(CompactLinkedHashSetTest.class);
-    suite.addTestSuite(FloodingTest.class);
     suite.addTest(
         SetTestSuiteBuilder.using(
                 new TestStringSetGenerator() {
@@ -106,12 +105,4 @@ public void testAllocArraysExpectedSize() {
     }
   }
 
-  public static class FloodingTest extends AbstractHashFloodingTest<Set<Object>> {
-    public FloodingTest() {
-      super(
-          ImmutableList.of(Construction.setFromElements(CompactLinkedHashSet::create)),
-          n -> n * Math.log(n),
-          ImmutableList.of(QueryOp.SET_CONTAINS));
-    }
-  }
 }
diff --git a/guava-tests/test/com/google/common/collect/DiscreteDomainTest.java b/guava-tests/test/com/google/common/collect/DiscreteDomainTest.java
index 5de3f8df2be1..b9e15fd9ca65 100644
--- a/guava-tests/test/com/google/common/collect/DiscreteDomainTest.java
+++ b/guava-tests/test/com/google/common/collect/DiscreteDomainTest.java
@@ -87,4 +87,48 @@ public void testBigIntegersOffsetExceptions() {
     } catch (IllegalArgumentException expected) {
     }
   }
+
+  public void testCustomOffsetExceptions() {
+    try {
+      new MyIntegerDomain().offset(0, -1);
+      fail();
+    } catch (IllegalArgumentException expected) {
+    }
+    try {
+      new MyIntegerDomain().offset(Integer.MAX_VALUE, 1);
+      fail();
+    } catch (IllegalArgumentException expected) {
+    }
+  }
+
+  private static final class MyIntegerDomain extends DiscreteDomain<Integer> {
+    static final DiscreteDomain<Integer> DELEGATE = DiscreteDomain.integers();
+
+    @Override
+    public Integer next(Integer value) {
+      return DELEGATE.next(value);
+    }
+
+    @Override
+    public Integer previous(Integer value) {
+      return DELEGATE.previous(value);
+    }
+
+    // Do *not* override offset() to delegate: We want to test the default implementation.
+
+    @Override
+    public long distance(Integer start, Integer end) {
+      return DELEGATE.distance(start, end);
+    }
+
+    @Override
+    public Integer minValue() {
+      return DELEGATE.minValue();
+    }
+
+    @Override
+    public Integer maxValue() {
+      return DELEGATE.maxValue();
+    }
+  }
 }
diff --git a/guava-tests/test/com/google/common/collect/ForwardingMapTest.java b/guava-tests/test/com/google/common/collect/ForwardingMapTest.java
index cc5d73967607..cf2ed0d3b5f1 100644
--- a/guava-tests/test/com/google/common/collect/ForwardingMapTest.java
+++ b/guava-tests/test/com/google/common/collect/ForwardingMapTest.java
@@ -170,7 +170,7 @@ protected Map<String, String> create(Entry<String, String>[] entries) {
                     for (Entry<String, String> entry : entries) {
                       builder.put(entry.getKey(), entry.getValue());
                     }
-                    return new StandardImplForwardingMap<>(builder.build());
+                    return new StandardImplForwardingMap<>(builder.buildOrThrow());
                   }
                 })
             .named("ForwardingMap[ImmutableMap] with standard implementations")
diff --git a/guava-tests/test/com/google/common/collect/ImmutableBiMapTest.java b/guava-tests/test/com/google/common/collect/ImmutableBiMapTest.java
index 0f9542890fab..780dc37c0cbd 100644
--- a/guava-tests/test/com/google/common/collect/ImmutableBiMapTest.java
+++ b/guava-tests/test/com/google/common/collect/ImmutableBiMapTest.java
@@ -37,6 +37,7 @@
 import com.google.common.testing.CollectorTester;
 import com.google.common.testing.SerializableTester;
 import com.google.errorprone.annotations.CanIgnoreReturnValue;
+import java.util.AbstractMap;
 import java.util.Arrays;
 import java.util.Collections;
 import java.util.EnumSet;
@@ -353,6 +354,7 @@ public void testBuilderPutNullValueViaPutAll() {
       }
     }
 
+    @SuppressWarnings("AlwaysThrows")
     public void testPuttingTheSameKeyTwiceThrowsOnBuild() {
       Builder<String, Integer> builder =
           new Builder<String, Integer>()
@@ -426,6 +428,136 @@ public void testOf() {
           "four",
           5,
           "five");
+      assertMapEquals(
+          ImmutableBiMap.of(
+              "one", 1,
+              "two", 2,
+              "three", 3,
+              "four", 4,
+              "five", 5,
+              "six", 6),
+          "one",
+          1,
+          "two",
+          2,
+          "three",
+          3,
+          "four",
+          4,
+          "five",
+          5,
+          "six",
+          6);
+      assertMapEquals(
+          ImmutableBiMap.of(
+              "one", 1,
+              "two", 2,
+              "three", 3,
+              "four", 4,
+              "five", 5,
+              "six", 6,
+              "seven", 7),
+          "one",
+          1,
+          "two",
+          2,
+          "three",
+          3,
+          "four",
+          4,
+          "five",
+          5,
+          "six",
+          6,
+          "seven",
+          7);
+      assertMapEquals(
+          ImmutableBiMap.of(
+              "one", 1,
+              "two", 2,
+              "three", 3,
+              "four", 4,
+              "five", 5,
+              "six", 6,
+              "seven", 7,
+              "eight", 8),
+          "one",
+          1,
+          "two",
+          2,
+          "three",
+          3,
+          "four",
+          4,
+          "five",
+          5,
+          "six",
+          6,
+          "seven",
+          7,
+          "eight",
+          8);
+      assertMapEquals(
+          ImmutableBiMap.of(
+              "one", 1,
+              "two", 2,
+              "three", 3,
+              "four", 4,
+              "five", 5,
+              "six", 6,
+              "seven", 7,
+              "eight", 8,
+              "nine", 9),
+          "one",
+          1,
+          "two",
+          2,
+          "three",
+          3,
+          "four",
+          4,
+          "five",
+          5,
+          "six",
+          6,
+          "seven",
+          7,
+          "eight",
+          8,
+          "nine",
+          9);
+      assertMapEquals(
+          ImmutableBiMap.of(
+              "one", 1,
+              "two", 2,
+              "three", 3,
+              "four", 4,
+              "five", 5,
+              "six", 6,
+              "seven", 7,
+              "eight", 8,
+              "nine", 9,
+              "ten", 10),
+          "one",
+          1,
+          "two",
+          2,
+          "three",
+          3,
+          "four",
+          4,
+          "five",
+          5,
+          "six",
+          6,
+          "seven",
+          7,
+          "eight",
+          8,
+          "nine",
+          9,
+          "ten",
+          10);
     }
 
     public void testOfNullKey() {
@@ -456,6 +588,7 @@ public void testOfNullValue() {
       }
     }
 
+    @SuppressWarnings("AlwaysThrows")
     public void testOfWithDuplicateKey() {
       try {
         ImmutableBiMap.of("one", 1, "one", 1);
@@ -465,6 +598,30 @@ public void testOfWithDuplicateKey() {
       }
     }
 
+    public void testOfEntries() {
+      assertMapEquals(
+          ImmutableBiMap.ofEntries(entry("one", 1), entry("two", 2)), "one", 1, "two", 2);
+    }
+
+    public void testOfEntriesNull() {
+      Entry<Integer, Integer> nullKey = entry(null, 23);
+      try {
+        ImmutableBiMap.ofEntries(nullKey);
+        fail();
+      } catch (NullPointerException expected) {
+      }
+      Entry<Integer, Integer> nullValue = entry(23, null);
+      try {
+        ImmutableBiMap.ofEntries(nullValue);
+        fail();
+      } catch (NullPointerException expected) {
+      }
+    }
+
+    private static <T> Entry<T, T> entry(T key, T value) {
+      return new AbstractMap.SimpleImmutableEntry<>(key, value);
+    }
+
     public void testCopyOfEmptyMap() {
       ImmutableBiMap<String, Integer> copy =
           ImmutableBiMap.copyOf(Collections.<String, Integer>emptyMap());
@@ -516,7 +673,7 @@ public void testFromImmutableMap() {
                   .put("three", 3)
                   .put("four", 4)
                   .put("five", 5)
-                  .build());
+                  .buildOrThrow());
       assertMapEquals(bimap, "one", 1, "two", 2, "three", 3, "four", 4, "five", 5);
       assertMapEquals(bimap.inverse(), 1, "one", 2, "two", 3, "three", 4, "four", 5, "five");
     }
@@ -528,13 +685,14 @@ public void testDuplicateValues() {
               .put("two", 2)
               .put("uno", 1)
               .put("dos", 2)
-              .build();
+              .buildOrThrow();
 
       try {
         ImmutableBiMap.copyOf(map);
         fail();
       } catch (IllegalArgumentException expected) {
-        assertThat(expected.getMessage()).contains("1");
+        assertThat(expected.getMessage()).containsMatch("1|2");
+        // We don't specify which of the two dups should be reported.
       }
     }
 
@@ -566,6 +724,7 @@ public void testToImmutableBiMap_exceptionOnDuplicateKey() {
 
   public static class BiMapSpecificTests extends TestCase {
 
+    @SuppressWarnings("DoNotCall")
     public void testForcePut() {
       BiMap<String, Integer> bimap = ImmutableBiMap.copyOf(ImmutableMap.of("one", 1, "two", 2));
       try {
@@ -625,11 +784,11 @@ public void testInverseSerialization() {
   }
 
   private static <K, V> void assertMapEquals(Map<K, V> map, Object... alternatingKeysAndValues) {
-    int i = 0;
-    for (Entry<K, V> entry : map.entrySet()) {
-      assertEquals(alternatingKeysAndValues[i++], entry.getKey());
-      assertEquals(alternatingKeysAndValues[i++], entry.getValue());
+    Map<Object, Object> expected = new LinkedHashMap<>();
+    for (int i = 0; i < alternatingKeysAndValues.length; i += 2) {
+      expected.put(alternatingKeysAndValues[i], alternatingKeysAndValues[i + 1]);
     }
+    assertThat(map).containsExactlyEntriesIn(expected).inOrder();
   }
 
   public static class FloodingTest extends AbstractHashFloodingTest<BiMap<Object, Object>> {
diff --git a/guava-tests/test/com/google/common/collect/ImmutableListMultimapTest.java b/guava-tests/test/com/google/common/collect/ImmutableListMultimapTest.java
index d270610129e7..4e0bdda13070 100644
--- a/guava-tests/test/com/google/common/collect/ImmutableListMultimapTest.java
+++ b/guava-tests/test/com/google/common/collect/ImmutableListMultimapTest.java
@@ -32,6 +32,7 @@
 import com.google.common.collect.testing.google.UnmodifiableCollectionTests;
 import com.google.common.testing.CollectorTester;
 import com.google.common.testing.EqualsTester;
+import com.google.common.testing.NullPointerTester;
 import com.google.common.testing.SerializableTester;
 import java.util.Arrays;
 import java.util.Collection;
@@ -601,4 +602,13 @@ public void testEmptySerialization() {
     Multimap<String, Integer> multimap = ImmutableListMultimap.of();
     assertSame(multimap, SerializableTester.reserialize(multimap));
   }
+
+  @GwtIncompatible // reflection
+  public void testNulls() throws Exception {
+    NullPointerTester tester = new NullPointerTester();
+    tester.testAllPublicStaticMethods(ImmutableListMultimap.class);
+    tester.ignore(ImmutableListMultimap.class.getMethod("get", Object.class));
+    tester.testAllPublicInstanceMethods(ImmutableListMultimap.of());
+    tester.testAllPublicInstanceMethods(ImmutableListMultimap.of("a", 1));
+  }
 }
diff --git a/guava-tests/test/com/google/common/collect/ImmutableMapTest.java b/guava-tests/test/com/google/common/collect/ImmutableMapTest.java
index 34d1e21d7ffc..63ce08a9c9e3 100644
--- a/guava-tests/test/com/google/common/collect/ImmutableMapTest.java
+++ b/guava-tests/test/com/google/common/collect/ImmutableMapTest.java
@@ -19,6 +19,7 @@
 import static com.google.common.collect.testing.Helpers.mapEntry;
 import static com.google.common.testing.SerializableTester.reserialize;
 import static com.google.common.truth.Truth.assertThat;
+import static com.google.common.truth.Truth.assertWithMessage;
 
 import com.google.common.annotations.GwtCompatible;
 import com.google.common.annotations.GwtIncompatible;
@@ -64,6 +65,8 @@
 import java.util.Map;
 import java.util.Map.Entry;
 import java.util.Set;
+import java.util.regex.Matcher;
+import java.util.regex.Pattern;
 import java.util.stream.Collector;
 import java.util.stream.Stream;
 import junit.framework.Test;
@@ -77,6 +80,7 @@
  * @author Jesse Wilson
  */
 @GwtCompatible(emulated = true)
+@SuppressWarnings("AlwaysThrows")
 public class ImmutableMapTest extends TestCase {
 
   @GwtIncompatible // suite
@@ -207,7 +211,7 @@ protected Map<K, V> makeEmptyMap() {
       throw new UnsupportedOperationException();
     }
 
-    private static final Joiner joiner = Joiner.on(", ");
+    private static final Joiner JOINER = Joiner.on(", ");
 
     @Override
     protected void assertMoreInvariants(Map<K, V> map) {
@@ -216,10 +220,10 @@ protected void assertMoreInvariants(Map<K, V> map) {
         assertEquals(entry.getKey() + "=" + entry.getValue(), entry.toString());
       }
 
-      assertEquals("{" + joiner.join(map.entrySet()) + "}", map.toString());
-      assertEquals("[" + joiner.join(map.entrySet()) + "]", map.entrySet().toString());
-      assertEquals("[" + joiner.join(map.keySet()) + "]", map.keySet().toString());
-      assertEquals("[" + joiner.join(map.values()) + "]", map.values().toString());
+      assertEquals("{" + JOINER.join(map.entrySet()) + "}", map.toString());
+      assertEquals("[" + JOINER.join(map.entrySet()) + "]", map.entrySet().toString());
+      assertEquals("[" + JOINER.join(map.keySet()) + "]", map.keySet().toString());
+      assertEquals("[" + JOINER.join(map.values()) + "]", map.values().toString());
 
       assertEquals(MinimalSet.from(map.entrySet()), map.entrySet());
       assertEquals(Sets.newHashSet(map.keySet()), map.keySet());
@@ -347,12 +351,13 @@ protected Map<Integer, UnhashableObject> makePopulatedMap() {
 
   public static class CreationTests extends TestCase {
     public void testEmptyBuilder() {
-      ImmutableMap<String, Integer> map = new Builder<String, Integer>().build();
+      ImmutableMap<String, Integer> map = new Builder<String, Integer>().buildOrThrow();
       assertEquals(Collections.<String, Integer>emptyMap(), map);
     }
 
     public void testSingletonBuilder() {
-      ImmutableMap<String, Integer> map = new Builder<String, Integer>().put("one", 1).build();
+      ImmutableMap<String, Integer> map =
+          new Builder<String, Integer>().put("one", 1).buildOrThrow();
       assertMapEquals(map, "one", 1);
     }
 
@@ -364,7 +369,7 @@ public void testBuilder() {
               .put("three", 3)
               .put("four", 4)
               .put("five", 5)
-              .build();
+              .buildOrThrow();
       assertMapEquals(map, "one", 1, "two", 2, "three", 3, "four", 4, "five", 5);
     }
 
@@ -377,7 +382,7 @@ public void testBuilderExactlySizedReusesArray() {
       }
       Entry<Integer, Integer>[] builderArrayAfterPuts = builder.entries;
       RegularImmutableMap<Integer, Integer> map =
-          (RegularImmutableMap<Integer, Integer>) builder.build();
+          (RegularImmutableMap<Integer, Integer>) builder.buildOrThrow();
       Entry<Integer, Integer>[] mapInternalArray = map.entries;
       assertSame(builderArray, builderArrayAfterPuts);
       assertSame(builderArray, mapInternalArray);
@@ -392,16 +397,16 @@ public void testBuilder_orderEntriesByValue() {
               .put("five", 5)
               .put("four", 4)
               .put("two", 2)
-              .build();
+              .buildOrThrow();
       assertMapEquals(map, "one", 1, "two", 2, "three", 3, "four", 4, "five", 5);
     }
 
     public void testBuilder_orderEntriesByValueAfterExactSizeBuild() {
       Builder<String, Integer> builder =
           new Builder<String, Integer>(2).put("four", 4).put("one", 1);
-      ImmutableMap<String, Integer> keyOrdered = builder.build();
+      ImmutableMap<String, Integer> keyOrdered = builder.buildOrThrow();
       ImmutableMap<String, Integer> valueOrdered =
-          builder.orderEntriesByValue(Ordering.natural()).build();
+          builder.orderEntriesByValue(Ordering.natural()).buildOrThrow();
       assertMapEquals(keyOrdered, "four", 4, "one", 1);
       assertMapEquals(valueOrdered, "one", 1, "four", 4);
     }
@@ -416,9 +421,45 @@ public void testBuilder_orderEntriesByValue_usedTwiceFails() {
       }
     }
 
+    @GwtIncompatible // we haven't implemented this
+    public void testBuilder_orderEntriesByValue_keepingLast() {
+      ImmutableMap.Builder<String, Integer> builder =
+          new Builder<String, Integer>()
+              .orderEntriesByValue(Ordering.natural())
+              .put("three", 3)
+              .put("one", 1)
+              .put("five", 5)
+              .put("four", 3)
+              .put("four", 5)
+              .put("four", 4) // this should win because it's last
+              .put("two", 2);
+      assertMapEquals(
+          builder.buildKeepingLast(), "one", 1, "two", 2, "three", 3, "four", 4, "five", 5);
+      try {
+        builder.buildOrThrow();
+        fail("Expected exception from duplicate keys");
+      } catch (IllegalArgumentException expected) {
+      }
+    }
+
+    @GwtIncompatible // we haven't implemented this
+    public void testBuilder_orderEntriesByValue_keepingLast_builderSizeFieldPreserved() {
+      ImmutableMap.Builder<String, Integer> builder =
+          new Builder<String, Integer>()
+              .orderEntriesByValue(Ordering.natural())
+              .put("one", 1)
+              .put("one", 1);
+      assertMapEquals(builder.buildKeepingLast(), "one", 1);
+      try {
+        builder.buildOrThrow();
+        fail("Expected exception from duplicate keys");
+      } catch (IllegalArgumentException expected) {
+      }
+    }
+
     public void testBuilder_withImmutableEntry() {
       ImmutableMap<String, Integer> map =
-          new Builder<String, Integer>().put(Maps.immutableEntry("one", 1)).build();
+          new Builder<String, Integer>().put(Maps.immutableEntry("one", 1)).buildOrThrow();
       assertMapEquals(map, "one", 1);
     }
 
@@ -459,12 +500,14 @@ public Integer getValue() {
 
       builder.put(entry);
       holder.string = "two";
-      assertMapEquals(builder.build(), "one", 1);
+      assertMapEquals(builder.buildOrThrow(), "one", 1);
     }
 
     public void testBuilderPutAllWithEmptyMap() {
       ImmutableMap<String, Integer> map =
-          new Builder<String, Integer>().putAll(Collections.<String, Integer>emptyMap()).build();
+          new Builder<String, Integer>()
+              .putAll(Collections.<String, Integer>emptyMap())
+              .buildOrThrow();
       assertEquals(Collections.<String, Integer>emptyMap(), map);
     }
 
@@ -478,14 +521,14 @@ public void testBuilderPutAll() {
       moreToPut.put("five", 5);
 
       ImmutableMap<String, Integer> map =
-          new Builder<String, Integer>().putAll(toPut).putAll(moreToPut).build();
+          new Builder<String, Integer>().putAll(toPut).putAll(moreToPut).buildOrThrow();
       assertMapEquals(map, "one", 1, "two", 2, "three", 3, "four", 4, "five", 5);
     }
 
     public void testBuilderReuse() {
       Builder<String, Integer> builder = new Builder<>();
-      ImmutableMap<String, Integer> mapOne = builder.put("one", 1).put("two", 2).build();
-      ImmutableMap<String, Integer> mapTwo = builder.put("three", 3).put("four", 4).build();
+      ImmutableMap<String, Integer> mapOne = builder.put("one", 1).put("two", 2).buildOrThrow();
+      ImmutableMap<String, Integer> mapTwo = builder.put("three", 3).put("four", 4).buildOrThrow();
 
       assertMapEquals(mapOne, "one", 1, "two", 2);
       assertMapEquals(mapTwo, "one", 1, "two", 2, "three", 3, "four", 4);
@@ -499,7 +542,7 @@ public void testBuilderPutNullKeyFailsAtomically() {
       } catch (NullPointerException expected) {
       }
       builder.put("foo", 2);
-      assertMapEquals(builder.build(), "foo", 2);
+      assertMapEquals(builder.buildOrThrow(), "foo", 2);
     }
 
     public void testBuilderPutImmutableEntryWithNullKeyFailsAtomically() {
@@ -510,7 +553,7 @@ public void testBuilderPutImmutableEntryWithNullKeyFailsAtomically() {
       } catch (NullPointerException expected) {
       }
       builder.put("foo", 2);
-      assertMapEquals(builder.build(), "foo", 2);
+      assertMapEquals(builder.buildOrThrow(), "foo", 2);
     }
 
     // for GWT compatibility
@@ -542,7 +585,7 @@ public void testBuilderPutMutableEntryWithNullKeyFailsAtomically() {
       } catch (NullPointerException expected) {
       }
       builder.put("foo", 2);
-      assertMapEquals(builder.build(), "foo", 2);
+      assertMapEquals(builder.buildOrThrow(), "foo", 2);
     }
 
     public void testBuilderPutNullKey() {
@@ -585,15 +628,154 @@ public void testPuttingTheSameKeyTwiceThrowsOnBuild() {
       Builder<String, Integer> builder =
           new Builder<String, Integer>()
               .put("one", 1)
-              .put("one", 1); // throwing on this line would be even better
+              .put("one", 1); // throwing on this line might be better but it's too late to change
 
       try {
-        builder.build();
+        builder.buildOrThrow();
         fail();
       } catch (IllegalArgumentException expected) {
       }
     }
 
+    public void testBuildKeepingLast_allowsOverwrite() {
+      Builder<Integer, String> builder =
+          new Builder<Integer, String>()
+              .put(1, "un")
+              .put(2, "deux")
+              .put(70, "soixante-dix")
+              .put(70, "septante")
+              .put(70, "seventy")
+              .put(1, "one")
+              .put(2, "two");
+      ImmutableMap<Integer, String> map = builder.buildKeepingLast();
+      assertMapEquals(map, 1, "one", 2, "two", 70, "seventy");
+    }
+
+    public void testBuildKeepingLast_smallTableSameHash() {
+      String key1 = "QED";
+      String key2 = "R&D";
+      assertThat(key1.hashCode()).isEqualTo(key2.hashCode());
+      ImmutableMap<String, Integer> map =
+          ImmutableMap.<String, Integer>builder()
+              .put(key1, 1)
+              .put(key2, 2)
+              .put(key1, 3)
+              .put(key2, 4)
+              .buildKeepingLast();
+      assertMapEquals(map, key1, 3, key2, 4);
+    }
+
+    // The java7 branch has different code depending on whether the entry indexes fit in a byte,
+    // short, or int. The small table in testBuildKeepingLast_allowsOverwrite will test the byte
+    // case. This method tests the short case.
+    public void testBuildKeepingLast_shortTable() {
+      Builder<Integer, String> builder = ImmutableMap.builder();
+      Map<Integer, String> expected = new LinkedHashMap<>();
+      for (int i = 0; i < 1000; i++) {
+        // Truncate to even key, so we have put(0, "0") then put(0, "1"). Half the entries are
+        // duplicates.
+        Integer key = i & ~1;
+        String value = String.valueOf(i);
+        builder.put(key, value);
+        expected.put(key, value);
+      }
+      ImmutableMap<Integer, String> map = builder.buildKeepingLast();
+      assertThat(map).hasSize(500);
+      assertThat(map).containsExactlyEntriesIn(expected).inOrder();
+    }
+
+    // This method tests the int case.
+    public void testBuildKeepingLast_bigTable() {
+      Builder<Integer, String> builder = ImmutableMap.builder();
+      Map<Integer, String> expected = new LinkedHashMap<>();
+      for (int i = 0; i < 200_000; i++) {
+        // Truncate to even key, so we have put(0, "0") then put(0, "1"). Half the entries are
+        // duplicates.
+        Integer key = i & ~1;
+        String value = String.valueOf(i);
+        builder.put(key, value);
+        expected.put(key, value);
+      }
+      ImmutableMap<Integer, String> map = builder.buildKeepingLast();
+      assertThat(map).hasSize(100_000);
+      assertThat(map).containsExactlyEntriesIn(expected).inOrder();
+    }
+
+    private static class ClassWithTerribleHashCode
+        implements Comparable<ClassWithTerribleHashCode> {
+      private final int value;
+
+      ClassWithTerribleHashCode(int value) {
+        this.value = value;
+      }
+
+      @Override
+      public int compareTo(ClassWithTerribleHashCode that) {
+        return Integer.compare(this.value, that.value);
+      }
+
+      @Override
+      public boolean equals(Object x) {
+        return x instanceof ClassWithTerribleHashCode
+            && ((ClassWithTerribleHashCode) x).value == value;
+      }
+
+      @Override
+      public int hashCode() {
+        return 23;
+      }
+
+      @Override
+      public String toString() {
+        return "ClassWithTerribleHashCode(" + value + ")";
+      }
+    }
+
+    @GwtIncompatible
+    public void testBuildKeepingLast_collisions() {
+      Map<ClassWithTerribleHashCode, Integer> expected = new LinkedHashMap<>();
+      Builder<ClassWithTerribleHashCode, Integer> builder = new Builder<>();
+      int size = RegularImmutableMap.MAX_HASH_BUCKET_LENGTH + 10;
+      for (int i = 0; i < size; i++) {
+        ClassWithTerribleHashCode key = new ClassWithTerribleHashCode(i);
+        builder.put(key, i);
+        builder.put(key, -i);
+        expected.put(key, -i);
+      }
+      ImmutableMap<ClassWithTerribleHashCode, Integer> map = builder.buildKeepingLast();
+      assertThat(map).containsExactlyEntriesIn(expected).inOrder();
+      assertThat(map).isInstanceOf(JdkBackedImmutableMap.class);
+    }
+
+    @GwtIncompatible // Pattern, Matcher
+    public void testBuilder_keepingLast_thenOrThrow() {
+      ImmutableMap.Builder<String, Integer> builder =
+          new Builder<String, Integer>()
+              .put("three", 3)
+              .put("one", 1)
+              .put("five", 5)
+              .put("four", 3)
+              .put("four", 5)
+              .put("four", 4) // this should win because it's last
+              .put("two", 2);
+      assertMapEquals(
+          builder.buildKeepingLast(), "three", 3, "one", 1, "five", 5, "four", 4, "two", 2);
+      try {
+        builder.buildOrThrow();
+        fail("Expected exception from duplicate keys");
+      } catch (IllegalArgumentException expected) {
+        // We don't really care which values the exception message contains, but they should be
+        // different from each other. If buildKeepingLast() collapsed duplicates, that might end up
+        // not being true.
+        Pattern pattern =
+            Pattern.compile("Multiple entries with same key: four=(.*) and four=(.*)");
+        assertThat(expected).hasMessageThat().matches(pattern);
+        Matcher matcher = pattern.matcher(expected.getMessage());
+        assertThat(matcher.matches()).isTrue();
+        assertThat(matcher.group(1)).isNotEqualTo(matcher.group(2));
+      }
+    }
+
     public void testOf() {
       assertMapEquals(ImmutableMap.of("one", 1), "one", 1);
       assertMapEquals(ImmutableMap.of("one", 1, "two", 2), "one", 1, "two", 2);
@@ -621,6 +803,136 @@ public void testOf() {
           4,
           "five",
           5);
+      assertMapEquals(
+          ImmutableMap.of(
+              "one", 1,
+              "two", 2,
+              "three", 3,
+              "four", 4,
+              "five", 5,
+              "six", 6),
+          "one",
+          1,
+          "two",
+          2,
+          "three",
+          3,
+          "four",
+          4,
+          "five",
+          5,
+          "six",
+          6);
+      assertMapEquals(
+          ImmutableMap.of(
+              "one", 1,
+              "two", 2,
+              "three", 3,
+              "four", 4,
+              "five", 5,
+              "six", 6,
+              "seven", 7),
+          "one",
+          1,
+          "two",
+          2,
+          "three",
+          3,
+          "four",
+          4,
+          "five",
+          5,
+          "six",
+          6,
+          "seven",
+          7);
+      assertMapEquals(
+          ImmutableMap.of(
+              "one", 1,
+              "two", 2,
+              "three", 3,
+              "four", 4,
+              "five", 5,
+              "six", 6,
+              "seven", 7,
+              "eight", 8),
+          "one",
+          1,
+          "two",
+          2,
+          "three",
+          3,
+          "four",
+          4,
+          "five",
+          5,
+          "six",
+          6,
+          "seven",
+          7,
+          "eight",
+          8);
+      assertMapEquals(
+          ImmutableMap.of(
+              "one", 1,
+              "two", 2,
+              "three", 3,
+              "four", 4,
+              "five", 5,
+              "six", 6,
+              "seven", 7,
+              "eight", 8,
+              "nine", 9),
+          "one",
+          1,
+          "two",
+          2,
+          "three",
+          3,
+          "four",
+          4,
+          "five",
+          5,
+          "six",
+          6,
+          "seven",
+          7,
+          "eight",
+          8,
+          "nine",
+          9);
+      assertMapEquals(
+          ImmutableMap.of(
+              "one", 1,
+              "two", 2,
+              "three", 3,
+              "four", 4,
+              "five", 5,
+              "six", 6,
+              "seven", 7,
+              "eight", 8,
+              "nine", 9,
+              "ten", 10),
+          "one",
+          1,
+          "two",
+          2,
+          "three",
+          3,
+          "four",
+          4,
+          "five",
+          5,
+          "six",
+          6,
+          "seven",
+          7,
+          "eight",
+          8,
+          "nine",
+          9,
+          "ten",
+          10);
     }
 
     public void testOfNullKey() {
@@ -763,12 +1075,11 @@ public void testNullPointers() {
   }
 
   private static <K, V> void assertMapEquals(Map<K, V> map, Object... alternatingKeysAndValues) {
-    assertEquals(map.size(), alternatingKeysAndValues.length / 2);
-    int i = 0;
-    for (Entry<K, V> entry : map.entrySet()) {
-      assertEquals(alternatingKeysAndValues[i++], entry.getKey());
-      assertEquals(alternatingKeysAndValues[i++], entry.getValue());
+    Map<Object, Object> expected = new LinkedHashMap<>();
+    for (int i = 0; i < alternatingKeysAndValues.length; i += 2) {
+      expected.put(alternatingKeysAndValues[i], alternatingKeysAndValues[i + 1]);
     }
+    assertThat(map).containsExactlyEntriesIn(expected).inOrder();
   }
 
   private static class IntHolder implements Serializable {
@@ -838,7 +1149,8 @@ class NonSerializableClass {}
     Entry<String, NonSerializableClass>[] entries =
         arrayOf(ImmutableMap.entryOf("one", new NonSerializableClass()));
 
-    Map<String, NonSerializableClass> map = JdkBackedImmutableMap.create(1, entries);
+    ImmutableMap<String, NonSerializableClass> map =
+        JdkBackedImmutableMap.create(1, entries, /* throwIfDuplicateKeys= */ true);
     Set<String> set = map.keySet();
 
     LenientSerializableTester.reserializeAndAssertLenient(set);
@@ -862,7 +1174,8 @@ class NonSerializableClass {}
     Entry<NonSerializableClass, String>[] entries =
         arrayOf(ImmutableMap.entryOf(new NonSerializableClass(), "value"));
 
-    Map<NonSerializableClass, String> map = JdkBackedImmutableMap.create(1, entries);
+    ImmutableMap<NonSerializableClass, String> map =
+        JdkBackedImmutableMap.create(1, entries, /* throwIfDuplicateKeys= */ true);
     Collection<String> collection = map.values();
 
     LenientSerializableTester.reserializeAndAssertElementsEqual(collection);
@@ -910,7 +1223,8 @@ public void ignore_testSerializationNoDuplication_jdkBackedImmutableMap() throws
       entries[i] = ImmutableMap.entryOf(i, i);
     }
 
-    ImmutableMap<Integer, Integer> map = JdkBackedImmutableMap.create(entries.length, entries);
+    ImmutableMap<Integer, Integer> map =
+        JdkBackedImmutableMap.create(entries.length, entries, /* throwIfDuplicateKeys= */ true);
     Set<Integer> keySet = map.keySet();
     Collection<Integer> values = map.values();
 
@@ -943,24 +1257,96 @@ public void testKeySetSplittable() {
             .put(4, 4)
             .put(5, 5)
             .put(6, 6)
-            .build();
+            .buildOrThrow();
     assertNotNull(map.keySet().spliterator().trySplit());
   }
 
   public void testEquals() {
     new EqualsTester()
-        .addEqualityGroup(ImmutableMap.of(), ImmutableMap.builder().build())
-        .addEqualityGroup(ImmutableMap.of(1, 1), ImmutableMap.builder().put(1, 1).build())
-        .addEqualityGroup(ImmutableMap.of(1, 1, 2, 2))
-        .addEqualityGroup(ImmutableMap.of(1, 1, 2, 2, 3, 3))
-        .addEqualityGroup(ImmutableMap.of(1, 4, 2, 2, 3, 3))
-        .addEqualityGroup(ImmutableMap.of(1, 1, 2, 4, 3, 3))
-        .addEqualityGroup(ImmutableMap.of(1, 1, 2, 2, 3, 4))
-        .addEqualityGroup(ImmutableMap.of(1, 2, 2, 3, 3, 1))
-        .addEqualityGroup(ImmutableMap.of(1, 1, 2, 2, 3, 3, 4, 4))
+        .addEqualityGroup(
+            ImmutableMap.of(),
+            ImmutableMap.builder().buildOrThrow(),
+            ImmutableMap.ofEntries(),
+            map())
+        .addEqualityGroup(
+            ImmutableMap.of(1, 1),
+            ImmutableMap.builder().put(1, 1).buildOrThrow(),
+            ImmutableMap.ofEntries(entry(1, 1)),
+            map(1, 1))
+        .addEqualityGroup(
+            ImmutableMap.of(1, 1, 2, 2),
+            ImmutableMap.builder().put(1, 1).put(2, 2).buildOrThrow(),
+            ImmutableMap.ofEntries(entry(1, 1), entry(2, 2)),
+            map(1, 1, 2, 2))
+        .addEqualityGroup(
+            ImmutableMap.of(1, 1, 2, 2, 3, 3),
+            ImmutableMap.builder().put(1, 1).put(2, 2).put(3, 3).buildOrThrow(),
+            ImmutableMap.ofEntries(entry(1, 1), entry(2, 2), entry(3, 3)),
+            map(1, 1, 2, 2, 3, 3))
+        .addEqualityGroup(
+            ImmutableMap.of(1, 4, 2, 2, 3, 3),
+            ImmutableMap.builder().put(1, 4).put(2, 2).put(3, 3).buildOrThrow(),
+            ImmutableMap.ofEntries(entry(1, 4), entry(2, 2), entry(3, 3)),
+            map(1, 4, 2, 2, 3, 3))
+        .addEqualityGroup(
+            ImmutableMap.of(1, 1, 2, 4, 3, 3),
+            ImmutableMap.builder().put(1, 1).put(2, 4).put(3, 3).buildOrThrow(),
+            ImmutableMap.ofEntries(entry(1, 1), entry(2, 4), entry(3, 3)),
+            map(1, 1, 2, 4, 3, 3))
+        .addEqualityGroup(
+            ImmutableMap.of(1, 1, 2, 2, 3, 4),
+            ImmutableMap.builder().put(1, 1).put(2, 2).put(3, 4).buildOrThrow(),
+            ImmutableMap.ofEntries(entry(1, 1), entry(2, 2), entry(3, 4)),
+            map(1, 1, 2, 2, 3, 4))
+        .addEqualityGroup(
+            ImmutableMap.of(1, 2, 2, 3, 3, 1),
+            ImmutableMap.builder().put(1, 2).put(2, 3).put(3, 1).buildOrThrow(),
+            ImmutableMap.ofEntries(entry(1, 2), entry(2, 3), entry(3, 1)),
+            map(1, 2, 2, 3, 3, 1))
+        .addEqualityGroup(
+            ImmutableMap.of(1, 1, 2, 2, 3, 3, 4, 4),
+            ImmutableMap.builder().put(1, 1).put(2, 2).put(3, 3).put(4, 4).buildOrThrow(),
+            ImmutableMap.ofEntries(entry(1, 1), entry(2, 2), entry(3, 3), entry(4, 4)),
+            map(1, 1, 2, 2, 3, 3, 4, 4))
+        .addEqualityGroup(
+            ImmutableMap.of(1, 1, 2, 2, 3, 3, 4, 4, 5, 5),
+            ImmutableMap.builder().put(1, 1).put(2, 2).put(3, 3).put(4, 4).put(5, 5).buildOrThrow(),
+            ImmutableMap.ofEntries(entry(1, 1), entry(2, 2), entry(3, 3), entry(4, 4), entry(5, 5)),
+            map(1, 1, 2, 2, 3, 3, 4, 4, 5, 5))
         .testEquals();
   }
 
+  public void testOfEntriesNull() {
+    Entry<Integer, Integer> nullKey = entry(null, 23);
+    try {
+      ImmutableMap.ofEntries(nullKey);
+      fail();
+    } catch (NullPointerException expected) {
+    }
+    Entry<Integer, Integer> nullValue = entry(23, null);
+    try {
+      ImmutableMap.ofEntries(nullValue);
+      fail();
+    } catch (NullPointerException expected) {
+    }
+  }
+
+  private static <T> Map<T, T> map(T... keysAndValues) {
+    assertThat(keysAndValues.length % 2).isEqualTo(0);
+    LinkedHashMap<T, T> map = new LinkedHashMap<>();
+    for (int i = 0; i < keysAndValues.length; i += 2) {
+      T key = keysAndValues[i];
+      T value = keysAndValues[i + 1];
+      T old = map.put(key, value);
+      assertWithMessage("Key %s set to %s and %s", key, value, old).that(old).isNull();
+    }
+    return map;
+  }
+
+  private static <T> Entry<T, T> entry(T key, T value) {
+    return new AbstractMap.SimpleImmutableEntry<>(key, value);
+  }
+
   public void testCopyOfMutableEntryList() {
     List<Entry<String, String>> entryList =
         Arrays.asList(
@@ -976,7 +1362,7 @@ public void testBuilderPutAllEntryList() {
         Arrays.asList(
             new AbstractMap.SimpleEntry<>("a", "1"), new AbstractMap.SimpleEntry<>("b", "2"));
     ImmutableMap<String, String> map =
-        ImmutableMap.<String, String>builder().putAll(entryList).build();
+        ImmutableMap.<String, String>builder().putAll(entryList).buildOrThrow();
     assertThat(map).containsExactly("a", "1", "b", "2").inOrder();
     entryList.get(0).setValue("3");
     assertThat(map).containsExactly("a", "1", "b", "2").inOrder();
@@ -1029,7 +1415,7 @@ public Map<Object, Object> create(List<?> keys) {
           for (Object k : keys) {
             builder.put(k, "dummy value");
           }
-          return builder.build();
+          return builder.buildOrThrow();
         }
       },
       BUILDER_PUT_ENTRIES_ONE_BY_ONE {
@@ -1039,7 +1425,7 @@ public Map<Object, Object> create(List<?> keys) {
           for (Object k : keys) {
             builder.put(Maps.immutableEntry(k, "dummy value"));
           }
-          return builder.build();
+          return builder.buildOrThrow();
         }
       },
       BUILDER_PUT_ALL_MAP {
@@ -1051,7 +1437,7 @@ public Map<Object, Object> create(List<?> keys) {
               throw new UnsupportedOperationException("duplicate key");
             }
           }
-          return ImmutableMap.builder().putAll(sourceMap).build();
+          return ImmutableMap.builder().putAll(sourceMap).buildOrThrow();
         }
       },
       BUILDER_PUT_ALL_ENTRIES {
@@ -1059,7 +1445,7 @@ public Map<Object, Object> create(List<?> keys) {
         public Map<Object, Object> create(List<?> keys) {
           return ImmutableMap.builder()
               .putAll(Lists.transform(keys, k -> Maps.immutableEntry(k, "dummy value")))
-              .build();
+              .buildOrThrow();
         }
       },
       FORCE_JDK {
diff --git a/guava-tests/test/com/google/common/collect/ImmutableMultimapTest.java b/guava-tests/test/com/google/common/collect/ImmutableMultimapTest.java
index 52632580c3e8..ac09593bac1d 100644
--- a/guava-tests/test/com/google/common/collect/ImmutableMultimapTest.java
+++ b/guava-tests/test/com/google/common/collect/ImmutableMultimapTest.java
@@ -17,11 +17,13 @@
 package com.google.common.collect;
 
 import com.google.common.annotations.GwtCompatible;
+import com.google.common.annotations.GwtIncompatible;
 import com.google.common.collect.ImmutableMultimap.Builder;
 import com.google.common.collect.testing.SampleElements;
 import com.google.common.collect.testing.SampleElements.Unhashables;
 import com.google.common.collect.testing.UnhashableObject;
 import com.google.common.testing.EqualsTester;
+import com.google.common.testing.NullPointerTester;
 import java.util.Arrays;
 import java.util.Map.Entry;
 import junit.framework.TestCase;
@@ -124,4 +126,13 @@ public void testEquals() {
             ImmutableMultimap.of(1, "a", 2, "b"), ImmutableMultimap.of(2, "b", 1, "a"))
         .testEquals();
   }
+
+  @GwtIncompatible // reflection
+  public void testNulls() throws Exception {
+    NullPointerTester tester = new NullPointerTester();
+    tester.testAllPublicStaticMethods(ImmutableMultimap.class);
+    tester.ignore(ImmutableListMultimap.class.getMethod("get", Object.class));
+    tester.testAllPublicInstanceMethods(ImmutableMultimap.of());
+    tester.testAllPublicInstanceMethods(ImmutableMultimap.of("a", 1));
+  }
 }
diff --git a/guava-tests/test/com/google/common/collect/ImmutableRangeSetTest.java b/guava-tests/test/com/google/common/collect/ImmutableRangeSetTest.java
index 1e365e28e34e..1fe56c7cccad 100644
--- a/guava-tests/test/com/google/common/collect/ImmutableRangeSetTest.java
+++ b/guava-tests/test/com/google/common/collect/ImmutableRangeSetTest.java
@@ -313,6 +313,7 @@ public void testMultipleBoundedAboveRanges() {
     assertEquals(expectedComplement, rangeSet.complement());
   }
 
+  @SuppressWarnings("DoNotCall")
   public void testAddUnsupported() {
     RangeSet<Integer> rangeSet =
         ImmutableRangeSet.<Integer>builder()
@@ -328,6 +329,7 @@ public void testAddUnsupported() {
     }
   }
 
+  @SuppressWarnings("DoNotCall")
   public void testAddAllUnsupported() {
     RangeSet<Integer> rangeSet =
         ImmutableRangeSet.<Integer>builder()
@@ -343,6 +345,7 @@ public void testAddAllUnsupported() {
     }
   }
 
+  @SuppressWarnings("DoNotCall")
   public void testRemoveUnsupported() {
     RangeSet<Integer> rangeSet =
         ImmutableRangeSet.<Integer>builder()
@@ -358,6 +361,7 @@ public void testRemoveUnsupported() {
     }
   }
 
+  @SuppressWarnings("DoNotCall")
   public void testRemoveAllUnsupported() {
     RangeSet<Integer> rangeSet =
         ImmutableRangeSet.<Integer>builder()
diff --git a/guava-tests/test/com/google/common/collect/ImmutableSetMultimapTest.java b/guava-tests/test/com/google/common/collect/ImmutableSetMultimapTest.java
index a1b2c0f56d77..842ba92865d8 100644
--- a/guava-tests/test/com/google/common/collect/ImmutableSetMultimapTest.java
+++ b/guava-tests/test/com/google/common/collect/ImmutableSetMultimapTest.java
@@ -32,6 +32,7 @@
 import com.google.common.collect.testing.google.UnmodifiableCollectionTests;
 import com.google.common.testing.CollectorTester;
 import com.google.common.testing.EqualsTester;
+import com.google.common.testing.NullPointerTester;
 import com.google.common.testing.SerializableTester;
 import java.util.Arrays;
 import java.util.Collection;
@@ -624,4 +625,13 @@ private ImmutableSetMultimap<String, Integer> createMultimap() {
         .put("foo", 3)
         .build();
   }
+
+  @GwtIncompatible // reflection
+  public void testNulls() throws Exception {
+    NullPointerTester tester = new NullPointerTester();
+    tester.testAllPublicStaticMethods(ImmutableSetMultimap.class);
+    tester.ignore(ImmutableSetMultimap.class.getMethod("get", Object.class));
+    tester.testAllPublicInstanceMethods(ImmutableSetMultimap.of());
+    tester.testAllPublicInstanceMethods(ImmutableSetMultimap.of("a", 1));
+  }
 }
diff --git a/guava-tests/test/com/google/common/collect/ImmutableSetTest.java b/guava-tests/test/com/google/common/collect/ImmutableSetTest.java
index 06d6a8e01398..1828517668ca 100644
--- a/guava-tests/test/com/google/common/collect/ImmutableSetTest.java
+++ b/guava-tests/test/com/google/common/collect/ImmutableSetTest.java
@@ -378,6 +378,12 @@ public void testEquals() {
         .testEquals();
   }
 
+  /**
+   * The maximum allowed probability of falsely detecting a hash flooding attack if the input is
+   * randomly generated.
+   */
+  private static final double HASH_FLOODING_FPP = 0.001;
+
   public void testReuseBuilderReducingHashTableSizeWithPowerOfTwoTotalElements() {
     ImmutableSet.Builder<Object> builder = ImmutableSet.builderWithExpectedSize(6);
     builder.add(0);
diff --git a/guava-tests/test/com/google/common/collect/ImmutableSortedMapTest.java b/guava-tests/test/com/google/common/collect/ImmutableSortedMapTest.java
index 63b0ded067d1..1de9e6972ed8 100644
--- a/guava-tests/test/com/google/common/collect/ImmutableSortedMapTest.java
+++ b/guava-tests/test/com/google/common/collect/ImmutableSortedMapTest.java
@@ -62,6 +62,7 @@
  * @author Jared Levy
  */
 @GwtCompatible(emulated = true)
+@SuppressWarnings("AlwaysThrows")
 public class ImmutableSortedMapTest extends TestCase {
   // TODO: Avoid duplicating code in ImmutableMapTest
 
@@ -488,6 +489,136 @@ public void testOf() {
           3,
           "two",
           2);
+      assertMapEquals(
+          ImmutableSortedMap.of(
+              "one", 1,
+              "two", 2,
+              "three", 3,
+              "four", 4,
+              "five", 5,
+              "six", 6),
+          "five",
+          5,
+          "four",
+          4,
+          "one",
+          1,
+          "six",
+          6,
+          "three",
+          3,
+          "two",
+          2);
+      assertMapEquals(
+          ImmutableSortedMap.of(
+              "one", 1,
+              "two", 2,
+              "three", 3,
+              "four", 4,
+              "five", 5,
+              "six", 6,
+              "seven", 7),
+          "five",
+          5,
+          "four",
+          4,
+          "one",
+          1,
+          "seven",
+          7,
+          "six",
+          6,
+          "three",
+          3,
+          "two",
+          2);
+      assertMapEquals(
+          ImmutableSortedMap.of(
+              "one", 1,
+              "two", 2,
+              "three", 3,
+              "four", 4,
+              "five", 5,
+              "six", 6,
+              "seven", 7,
+              "eight", 8),
+          "eight",
+          8,
+          "five",
+          5,
+          "four",
+          4,
+          "one",
+          1,
+          "seven",
+          7,
+          "six",
+          6,
+          "three",
+          3,
+          "two",
+          2);
+      assertMapEquals(
+          ImmutableSortedMap.of(
+              "one", 1,
+              "two", 2,
+              "three", 3,
+              "four", 4,
+              "five", 5,
+              "six", 6,
+              "seven", 7,
+              "eight", 8,
+              "nine", 9),
+          "eight",
+          8,
+          "five",
+          5,
+          "four",
+          4,
+          "nine",
+          9,
+          "one",
+          1,
+          "seven",
+          7,
+          "six",
+          6,
+          "three",
+          3,
+          "two",
+          2);
+      assertMapEquals(
+          ImmutableSortedMap.of(
+              "one", 1,
+              "two", 2,
+              "three", 3,
+              "four", 4,
+              "five", 5,
+              "six", 6,
+              "seven", 7,
+              "eight", 8,
+              "nine", 9,
+              "ten", 10),
+          "eight",
+          8,
+          "five",
+          5,
+          "four",
+          4,
+          "nine",
+          9,
+          "one",
+          1,
+          "seven",
+          7,
+          "six",
+          6,
+          "ten",
+          10,
+          "three",
+          3,
+          "two",
+          2);
     }
 
     public void testOfNullKey() {
@@ -774,12 +905,11 @@ public void testNullValuesInCopyOfEntries() {
   }
 
   private static <K, V> void assertMapEquals(Map<K, V> map, Object... alternatingKeysAndValues) {
-    assertEquals(map.size(), alternatingKeysAndValues.length / 2);
-    int i = 0;
-    for (Entry<K, V> entry : map.entrySet()) {
-      assertEquals(alternatingKeysAndValues[i++], entry.getKey());
-      assertEquals(alternatingKeysAndValues[i++], entry.getValue());
+    Map<Object, Object> expected = new LinkedHashMap<>();
+    for (int i = 0; i < alternatingKeysAndValues.length; i += 2) {
+      expected.put(alternatingKeysAndValues[i], alternatingKeysAndValues[i + 1]);
     }
+    assertThat(map).containsExactlyEntriesIn(expected).inOrder();
   }
 
   private static class IntHolder implements Serializable {
diff --git a/guava-tests/test/com/google/common/collect/ImmutableSortedSetTest.java b/guava-tests/test/com/google/common/collect/ImmutableSortedSetTest.java
index 1f45227cda6e..b4cd891b2857 100644
--- a/guava-tests/test/com/google/common/collect/ImmutableSortedSetTest.java
+++ b/guava-tests/test/com/google/common/collect/ImmutableSortedSetTest.java
@@ -965,7 +965,7 @@ public void testLegacyComparable_builder_reverse() {
     assertTrue(Iterables.elementsEqual(LegacyComparable.VALUES_BACKWARD, set));
   }
 
-  @SuppressWarnings({"deprecation", "static-access"})
+  @SuppressWarnings({"deprecation", "static-access", "DoNotCall"})
   public void testBuilderMethod() {
     try {
       ImmutableSortedSet.builder();
diff --git a/guava-tests/test/com/google/common/collect/IteratorsTest.java b/guava-tests/test/com/google/common/collect/IteratorsTest.java
index 15f7ccc2040a..e71c8bd51eea 100644
--- a/guava-tests/test/com/google/common/collect/IteratorsTest.java
+++ b/guava-tests/test/com/google/common/collect/IteratorsTest.java
@@ -74,6 +74,7 @@ public static Test suite() {
     return suite;
   }
 
+  @SuppressWarnings("DoNotCall")
   public void testEmptyIterator() {
     Iterator<String> iterator = Iterators.emptyIterator();
     assertFalse(iterator.hasNext());
@@ -89,6 +90,7 @@ public void testEmptyIterator() {
     }
   }
 
+  @SuppressWarnings("DoNotCall")
   public void testEmptyListIterator() {
     ListIterator<String> iterator = Iterators.emptyListIterator();
     assertFalse(iterator.hasNext());
@@ -1119,6 +1121,7 @@ public void testForArrayEmpty() {
     }
   }
 
+  @SuppressWarnings("DoNotCall")
   public void testForArrayTypical() {
     String[] array = {"foo", "bar"};
     Iterator<String> iterator = Iterators.forArray(array);
@@ -1205,6 +1208,7 @@ public void testForEnumerationEmpty() {
     }
   }
 
+  @SuppressWarnings("DoNotCall")
   public void testForEnumerationSingleton() {
     Enumeration<Integer> enumer = enumerate(1);
     Iterator<Integer> iter = Iterators.forEnumeration(enumer);
diff --git a/guava-tests/test/com/google/common/collect/ListsTest.java b/guava-tests/test/com/google/common/collect/ListsTest.java
index ef90e5493f96..33736d6d8116 100644
--- a/guava-tests/test/com/google/common/collect/ListsTest.java
+++ b/guava-tests/test/com/google/common/collect/ListsTest.java
@@ -619,14 +619,14 @@ public void testCartesianProduct_contains() {
 
   public void testCartesianProduct_indexOf() {
     List<List<Integer>> actual = Lists.cartesianProduct(list(1, 2), list(3, 4));
-    assertEquals(actual.indexOf(list(1, 3)), 0);
-    assertEquals(actual.indexOf(list(1, 4)), 1);
-    assertEquals(actual.indexOf(list(2, 3)), 2);
-    assertEquals(actual.indexOf(list(2, 4)), 3);
-    assertEquals(actual.indexOf(list(3, 1)), -1);
-
-    assertEquals(actual.indexOf(list(1)), -1);
-    assertEquals(actual.indexOf(list(1, 1, 1)), -1);
+    assertEquals(0, actual.indexOf(list(1, 3)));
+    assertEquals(1, actual.indexOf(list(1, 4)));
+    assertEquals(2, actual.indexOf(list(2, 3)));
+    assertEquals(3, actual.indexOf(list(2, 4)));
+    assertEquals(-1, actual.indexOf(list(3, 1)));
+
+    assertEquals(-1, actual.indexOf(list(1)));
+    assertEquals(-1, actual.indexOf(list(1, 1, 1)));
   }
 
   public void testCartesianProduct_lastIndexOf() {
diff --git a/guava-tests/test/com/google/common/collect/MapMakerTest.java b/guava-tests/test/com/google/common/collect/MapMakerTest.java
index 4b54f0dd5350..9669ded7c302 100644
--- a/guava-tests/test/com/google/common/collect/MapMakerTest.java
+++ b/guava-tests/test/com/google/common/collect/MapMakerTest.java
@@ -57,31 +57,28 @@ public T apply(T key) {
    * anywhere else
    */
 
-  /** Tests for the builder. */
-  public static class MakerTest extends TestCase {
-    public void testInitialCapacity_negative() {
-      MapMaker maker = new MapMaker();
-      try {
-        maker.initialCapacity(-1);
-        fail();
-      } catch (IllegalArgumentException expected) {
-      }
+  public void testInitialCapacity_negative() {
+    MapMaker maker = new MapMaker();
+    try {
+      maker.initialCapacity(-1);
+      fail();
+    } catch (IllegalArgumentException expected) {
     }
+  }
 
-    // TODO(cpovirk): enable when ready
-    public void xtestInitialCapacity_setTwice() {
-      MapMaker maker = new MapMaker().initialCapacity(16);
-      try {
-        // even to the same value is not allowed
-        maker.initialCapacity(16);
-        fail();
-      } catch (IllegalArgumentException expected) {
-      }
+  // TODO(cpovirk): enable when ready (apparently after a change to our GWT emulation)
+  public void xtestInitialCapacity_setTwice() {
+    MapMaker maker = new MapMaker().initialCapacity(16);
+    try {
+      // even to the same value is not allowed
+      maker.initialCapacity(16);
+      fail();
+    } catch (IllegalStateException expected) {
     }
+  }
 
-    public void testReturnsPlainConcurrentHashMapWhenPossible() {
-      Map<?, ?> map = new MapMaker().initialCapacity(5).makeMap();
-      assertTrue(map instanceof ConcurrentHashMap);
-    }
+  public void testReturnsPlainConcurrentHashMapWhenPossible() {
+    Map<?, ?> map = new MapMaker().initialCapacity(5).makeMap();
+    assertTrue(map instanceof ConcurrentHashMap);
   }
 }
diff --git a/guava-tests/test/com/google/common/collect/MapsTest.java b/guava-tests/test/com/google/common/collect/MapsTest.java
index 76394c883498..50df8cc5f0b7 100644
--- a/guava-tests/test/com/google/common/collect/MapsTest.java
+++ b/guava-tests/test/com/google/common/collect/MapsTest.java
@@ -1153,8 +1153,8 @@ public void testAsConverter_isAView() throws Exception {
     biMap.put("two", 2);
     Converter<String, Integer> converter = Maps.asConverter(biMap);
 
-    assertSame(1, converter.convert("one"));
-    assertSame(2, converter.convert("two"));
+    assertEquals((Integer) 1, converter.convert("one"));
+    assertEquals((Integer) 2, converter.convert("two"));
     try {
       converter.convert("three");
       fail();
@@ -1163,9 +1163,9 @@ public void testAsConverter_isAView() throws Exception {
 
     biMap.put("three", 3);
 
-    assertSame(1, converter.convert("one"));
-    assertSame(2, converter.convert("two"));
-    assertSame(3, converter.convert("three"));
+    assertEquals((Integer) 1, converter.convert("one"));
+    assertEquals((Integer) 2, converter.convert("two"));
+    assertEquals((Integer) 3, converter.convert("three"));
   }
 
   public void testAsConverter_withNullMapping() throws Exception {
@@ -1231,6 +1231,51 @@ public void testUnmodifiableBiMap() {
       fail("UnsupportedOperationException expected");
     } catch (UnsupportedOperationException expected) {
     }
+    try {
+      unmod.replaceAll((k, v) -> v);
+      fail("UnsupportedOperationException expected");
+    } catch (UnsupportedOperationException expected) {
+    }
+    try {
+      unmod.putIfAbsent(3, "three");
+      fail("UnsupportedOperationException expected");
+    } catch (UnsupportedOperationException expected) {
+    }
+    try {
+      unmod.replace(3, "three", "four");
+      fail("UnsupportedOperationException expected");
+    } catch (UnsupportedOperationException expected) {
+    }
+    try {
+      unmod.replace(3, "four");
+      fail("UnsupportedOperationException expected");
+    } catch (UnsupportedOperationException expected) {
+    }
+    try {
+      unmod.computeIfAbsent(3, (k) -> k + "three");
+      fail("UnsupportedOperationException expected");
+    } catch (UnsupportedOperationException expected) {
+    }
+    try {
+      unmod.computeIfPresent(4, (k, v) -> v);
+      fail("UnsupportedOperationException expected");
+    } catch (UnsupportedOperationException expected) {
+    }
+    try {
+      unmod.compute(4, (k, v) -> v);
+      fail("UnsupportedOperationException expected");
+    } catch (UnsupportedOperationException expected) {
+    }
+    try {
+      unmod.merge(4, "four", (k, v) -> v);
+      fail("UnsupportedOperationException expected");
+    } catch (UnsupportedOperationException expected) {
+    }
+    try {
+      unmod.clear();
+      fail("UnsupportedOperationException expected");
+    } catch (UnsupportedOperationException expected) {
+    }
 
     /* UnsupportedOperationException on indirect modifications. */
     BiMap<String, Number> inverse = unmod.inverse();
@@ -1857,6 +1902,51 @@ void ensureNotDirectlyModifiable(NavigableMap<Integer, String> unmod) {
       fail("UnsupportedOperationException expected");
     } catch (UnsupportedOperationException expected) {
     }
+    try {
+      unmod.replaceAll((k, v) -> v);
+      fail("UnsupportedOperationException expected");
+    } catch (UnsupportedOperationException expected) {
+    }
+    try {
+      unmod.putIfAbsent(3, "three");
+      fail("UnsupportedOperationException expected");
+    } catch (UnsupportedOperationException expected) {
+    }
+    try {
+      unmod.replace(3, "three", "four");
+      fail("UnsupportedOperationException expected");
+    } catch (UnsupportedOperationException expected) {
+    }
+    try {
+      unmod.replace(3, "four");
+      fail("UnsupportedOperationException expected");
+    } catch (UnsupportedOperationException expected) {
+    }
+    try {
+      unmod.computeIfAbsent(3, (k) -> k + "three");
+      fail("UnsupportedOperationException expected");
+    } catch (UnsupportedOperationException expected) {
+    }
+    try {
+      unmod.computeIfPresent(4, (k, v) -> v);
+      fail("UnsupportedOperationException expected");
+    } catch (UnsupportedOperationException expected) {
+    }
+    try {
+      unmod.compute(4, (k, v) -> v);
+      fail("UnsupportedOperationException expected");
+    } catch (UnsupportedOperationException expected) {
+    }
+    try {
+      unmod.merge(4, "four", (k, v) -> v);
+      fail("UnsupportedOperationException expected");
+    } catch (UnsupportedOperationException expected) {
+    }
+    try {
+      unmod.clear();
+      fail("UnsupportedOperationException expected");
+    } catch (UnsupportedOperationException expected) {
+    }
   }
 
   @GwtIncompatible // NavigableMap
diff --git a/guava-tests/test/com/google/common/collect/MoreCollectorsTest.java b/guava-tests/test/com/google/common/collect/MoreCollectorsTest.java
index f5c5f26ae1e0..65a8971350a2 100644
--- a/guava-tests/test/com/google/common/collect/MoreCollectorsTest.java
+++ b/guava-tests/test/com/google/common/collect/MoreCollectorsTest.java
@@ -57,6 +57,14 @@ public void testToOptionalMultiple() {
     }
   }
 
+  public void testToOptionalMultipleWithNull() {
+    try {
+      Stream.of(1, null).collect(MoreCollectors.toOptional());
+      fail("Expected NullPointerException");
+    } catch (NullPointerException expected) {
+    }
+  }
+
   public void testToOptionalMany() {
     try {
       Stream.of(1, 2, 3, 4, 5, 6).collect(MoreCollectors.toOptional());
diff --git a/guava-tests/test/com/google/common/collect/MultimapsTest.java b/guava-tests/test/com/google/common/collect/MultimapsTest.java
index 6fa9c3c8b9f8..738ba10ddecd 100644
--- a/guava-tests/test/com/google/common/collect/MultimapsTest.java
+++ b/guava-tests/test/com/google/common/collect/MultimapsTest.java
@@ -667,7 +667,8 @@ public void testNewMultimap() {
     assertEquals("[3, 1, 4]", ummodifiable.get(Color.BLUE).toString());
 
     Collection<Integer> collection = multimap.get(Color.BLUE);
-    assertEquals(collection, collection);
+    // Explicitly call `equals`; `assertEquals` might return fast
+    assertTrue(collection.equals(collection));
 
     assertFalse(multimap.keySet() instanceof SortedSet);
     assertFalse(multimap.asMap() instanceof SortedMap);
diff --git a/guava-tests/test/com/google/common/collect/RangeTest.java b/guava-tests/test/com/google/common/collect/RangeTest.java
index 9a2cd74161a8..e8578bfd199b 100644
--- a/guava-tests/test/com/google/common/collect/RangeTest.java
+++ b/guava-tests/test/com/google/common/collect/RangeTest.java
@@ -20,6 +20,7 @@
 import static com.google.common.collect.BoundType.OPEN;
 import static com.google.common.collect.DiscreteDomain.integers;
 import static com.google.common.testing.SerializableTester.reserializeAndAssert;
+import static com.google.common.truth.Truth.assertThat;
 import static java.util.Arrays.asList;
 
 import com.google.common.annotations.GwtCompatible;
@@ -349,11 +350,14 @@ public void testIntersection_empty() {
       range.intersection(Range.open(3, 5));
       fail();
     } catch (IllegalArgumentException expected) {
+      // TODO(kevinb): convert the rest of this file to Truth someday
+      assertThat(expected).hasMessageThat().contains("connected");
     }
     try {
       range.intersection(Range.closed(0, 2));
       fail();
     } catch (IllegalArgumentException expected) {
+      assertThat(expected).hasMessageThat().contains("connected");
     }
   }
 
@@ -368,11 +372,13 @@ public void testIntersection_deFactoEmpty() {
       range.intersection(Range.lessThan(3));
       fail();
     } catch (IllegalArgumentException expected) {
+      assertThat(expected).hasMessageThat().contains("connected");
     }
     try {
       range.intersection(Range.greaterThan(4));
       fail();
     } catch (IllegalArgumentException expected) {
+      assertThat(expected).hasMessageThat().contains("connected");
     }
 
     range = Range.closed(3, 4);
@@ -395,11 +401,13 @@ public void testIntersection_singleton() {
       range.intersection(Range.atLeast(4));
       fail();
     } catch (IllegalArgumentException expected) {
+      assertThat(expected).hasMessageThat().contains("connected");
     }
     try {
       range.intersection(Range.atMost(2));
       fail();
     } catch (IllegalArgumentException expected) {
+      assertThat(expected).hasMessageThat().contains("connected");
     }
   }
 
@@ -411,6 +419,7 @@ public void testIntersection_general() {
       range.intersection(Range.closed(0, 2));
       fail();
     } catch (IllegalArgumentException expected) {
+      assertThat(expected).hasMessageThat().contains("connected");
     }
 
     // adjacent below
@@ -451,6 +460,7 @@ public void testIntersection_general() {
       range.intersection(Range.closed(10, 12));
       fail();
     } catch (IllegalArgumentException expected) {
+      assertThat(expected).hasMessageThat().contains("connected");
     }
   }
 
diff --git a/guava-tests/test/com/google/common/collect/RegularImmutableAsListTest.java b/guava-tests/test/com/google/common/collect/RegularImmutableAsListTest.java
index b6c2358c590a..b0f9e16e4327 100644
--- a/guava-tests/test/com/google/common/collect/RegularImmutableAsListTest.java
+++ b/guava-tests/test/com/google/common/collect/RegularImmutableAsListTest.java
@@ -30,7 +30,8 @@ public class RegularImmutableAsListTest extends TestCase {
    */
   public void testDoesntCheckForNull() {
     ImmutableSet<Integer> set = ImmutableSet.of(1, 2, 3);
-    new RegularImmutableAsList<Integer>(set, new Object[] {null, null, null});
+    ImmutableList<Integer> unused =
+        new RegularImmutableAsList<Integer>(set, new Object[] {null, null, null});
     // shouldn't throw!
   }
 }
diff --git a/guava-tests/test/com/google/common/collect/SetOperationsTest.java b/guava-tests/test/com/google/common/collect/SetOperationsTest.java
index 7a1ec3a6590c..9a26f29457b3 100644
--- a/guava-tests/test/com/google/common/collect/SetOperationsTest.java
+++ b/guava-tests/test/com/google/common/collect/SetOperationsTest.java
@@ -291,92 +291,90 @@ protected Set<String> create(String[] elements) {
             .withFeatures(CollectionSize.ANY, CollectionFeature.ALLOWS_NULL_VALUES)
             .createTestSuite());
 
-    suite.addTestSuite(MoreTests.class);
+    suite.addTestSuite(SetOperationsTest.class);
     return suite;
   }
 
-  public static class MoreTests extends TestCase {
-    Set<String> friends;
-    Set<String> enemies;
-
-    @Override
-    public void setUp() {
-      friends = Sets.newHashSet("Tom", "Joe", "Dave");
-      enemies = Sets.newHashSet("Dick", "Harry", "Tom");
-    }
-
-    public void testUnion() {
-      Set<String> all = Sets.union(friends, enemies);
-      assertEquals(5, all.size());
-
-      ImmutableSet<String> immut = Sets.union(friends, enemies).immutableCopy();
-      HashSet<String> mut = Sets.union(friends, enemies).copyInto(new HashSet<String>());
-
-      enemies.add("Buck");
-      assertEquals(6, all.size());
-      assertEquals(5, immut.size());
-      assertEquals(5, mut.size());
-    }
-
-    public void testIntersection() {
-      Set<String> friends = Sets.newHashSet("Tom", "Joe", "Dave");
-      Set<String> enemies = Sets.newHashSet("Dick", "Harry", "Tom");
-
-      Set<String> frenemies = Sets.intersection(friends, enemies);
-      assertEquals(1, frenemies.size());
-
-      ImmutableSet<String> immut = Sets.intersection(friends, enemies).immutableCopy();
-      HashSet<String> mut = Sets.intersection(friends, enemies).copyInto(new HashSet<String>());
-
-      enemies.add("Joe");
-      assertEquals(2, frenemies.size());
-      assertEquals(1, immut.size());
-      assertEquals(1, mut.size());
-    }
-
-    public void testDifference() {
-      Set<String> friends = Sets.newHashSet("Tom", "Joe", "Dave");
-      Set<String> enemies = Sets.newHashSet("Dick", "Harry", "Tom");
-
-      Set<String> goodFriends = Sets.difference(friends, enemies);
-      assertEquals(2, goodFriends.size());
-
-      ImmutableSet<String> immut = Sets.difference(friends, enemies).immutableCopy();
-      HashSet<String> mut = Sets.difference(friends, enemies).copyInto(new HashSet<String>());
-
-      enemies.add("Dave");
-      assertEquals(1, goodFriends.size());
-      assertEquals(2, immut.size());
-      assertEquals(2, mut.size());
-    }
-
-    public void testSymmetricDifference() {
-      Set<String> friends = Sets.newHashSet("Tom", "Joe", "Dave");
-      Set<String> enemies = Sets.newHashSet("Dick", "Harry", "Tom");
-
-      Set<String> symmetricDifferenceFriendsFirst = Sets.symmetricDifference(friends, enemies);
-      assertEquals(4, symmetricDifferenceFriendsFirst.size());
-
-      Set<String> symmetricDifferenceEnemiesFirst = Sets.symmetricDifference(enemies, friends);
-      assertEquals(4, symmetricDifferenceEnemiesFirst.size());
-
-      assertEquals(symmetricDifferenceFriendsFirst, symmetricDifferenceEnemiesFirst);
-
-      ImmutableSet<String> immut = Sets.symmetricDifference(friends, enemies).immutableCopy();
-      HashSet<String> mut =
-          Sets.symmetricDifference(friends, enemies).copyInto(new HashSet<String>());
-
-      enemies.add("Dave");
-      assertEquals(3, symmetricDifferenceFriendsFirst.size());
-      assertEquals(4, immut.size());
-      assertEquals(4, mut.size());
-
-      immut = Sets.symmetricDifference(enemies, friends).immutableCopy();
-      mut = Sets.symmetricDifference(enemies, friends).copyInto(new HashSet<String>());
-      friends.add("Harry");
-      assertEquals(2, symmetricDifferenceEnemiesFirst.size());
-      assertEquals(3, immut.size());
-      assertEquals(3, mut.size());
-    }
+  Set<String> friends;
+  Set<String> enemies;
+
+  @Override
+  public void setUp() {
+    friends = Sets.newHashSet("Tom", "Joe", "Dave");
+    enemies = Sets.newHashSet("Dick", "Harry", "Tom");
+  }
+
+  public void testUnion() {
+    Set<String> all = Sets.union(friends, enemies);
+    assertEquals(5, all.size());
+
+    ImmutableSet<String> immut = Sets.union(friends, enemies).immutableCopy();
+    HashSet<String> mut = Sets.union(friends, enemies).copyInto(new HashSet<String>());
+
+    enemies.add("Buck");
+    assertEquals(6, all.size());
+    assertEquals(5, immut.size());
+    assertEquals(5, mut.size());
+  }
+
+  public void testIntersection() {
+    Set<String> friends = Sets.newHashSet("Tom", "Joe", "Dave");
+    Set<String> enemies = Sets.newHashSet("Dick", "Harry", "Tom");
+
+    Set<String> frenemies = Sets.intersection(friends, enemies);
+    assertEquals(1, frenemies.size());
+
+    ImmutableSet<String> immut = Sets.intersection(friends, enemies).immutableCopy();
+    HashSet<String> mut = Sets.intersection(friends, enemies).copyInto(new HashSet<String>());
+
+    enemies.add("Joe");
+    assertEquals(2, frenemies.size());
+    assertEquals(1, immut.size());
+    assertEquals(1, mut.size());
+  }
+
+  public void testDifference() {
+    Set<String> friends = Sets.newHashSet("Tom", "Joe", "Dave");
+    Set<String> enemies = Sets.newHashSet("Dick", "Harry", "Tom");
+
+    Set<String> goodFriends = Sets.difference(friends, enemies);
+    assertEquals(2, goodFriends.size());
+
+    ImmutableSet<String> immut = Sets.difference(friends, enemies).immutableCopy();
+    HashSet<String> mut = Sets.difference(friends, enemies).copyInto(new HashSet<String>());
+
+    enemies.add("Dave");
+    assertEquals(1, goodFriends.size());
+    assertEquals(2, immut.size());
+    assertEquals(2, mut.size());
+  }
+
+  public void testSymmetricDifference() {
+    Set<String> friends = Sets.newHashSet("Tom", "Joe", "Dave");
+    Set<String> enemies = Sets.newHashSet("Dick", "Harry", "Tom");
+
+    Set<String> symmetricDifferenceFriendsFirst = Sets.symmetricDifference(friends, enemies);
+    assertEquals(4, symmetricDifferenceFriendsFirst.size());
+
+    Set<String> symmetricDifferenceEnemiesFirst = Sets.symmetricDifference(enemies, friends);
+    assertEquals(4, symmetricDifferenceEnemiesFirst.size());
+
+    assertEquals(symmetricDifferenceFriendsFirst, symmetricDifferenceEnemiesFirst);
+
+    ImmutableSet<String> immut = Sets.symmetricDifference(friends, enemies).immutableCopy();
+    HashSet<String> mut =
+        Sets.symmetricDifference(friends, enemies).copyInto(new HashSet<String>());
+
+    enemies.add("Dave");
+    assertEquals(3, symmetricDifferenceFriendsFirst.size());
+    assertEquals(4, immut.size());
+    assertEquals(4, mut.size());
+
+    immut = Sets.symmetricDifference(enemies, friends).immutableCopy();
+    mut = Sets.symmetricDifference(enemies, friends).copyInto(new HashSet<String>());
+    friends.add("Harry");
+    assertEquals(2, symmetricDifferenceEnemiesFirst.size());
+    assertEquals(3, immut.size());
+    assertEquals(3, mut.size());
   }
 }
diff --git a/guava-tests/test/com/google/common/collect/SetsTest.java b/guava-tests/test/com/google/common/collect/SetsTest.java
index 86cb6c89c23e..72131bfc38b6 100644
--- a/guava-tests/test/com/google/common/collect/SetsTest.java
+++ b/guava-tests/test/com/google/common/collect/SetsTest.java
@@ -326,6 +326,7 @@ private enum SomeEnum {
     D
   }
 
+  @SuppressWarnings("DoNotCall")
   public void testImmutableEnumSet() {
     Set<SomeEnum> units = Sets.immutableEnumSet(SomeEnum.D, SomeEnum.B);
 
diff --git a/guava-tests/test/com/google/common/collect/SynchronizedDequeTest.java b/guava-tests/test/com/google/common/collect/SynchronizedDequeTest.java
index 0a11b27ab9ba..1df6aa1bffd1 100644
--- a/guava-tests/test/com/google/common/collect/SynchronizedDequeTest.java
+++ b/guava-tests/test/com/google/common/collect/SynchronizedDequeTest.java
@@ -254,6 +254,7 @@ public Iterator<E> descendingIterator() {
     private static final long serialVersionUID = 0;
   }
 
+  @SuppressWarnings("CheckReturnValue")
   public void testHoldsLockOnAllOperations() {
     create().element();
     create().offer("foo");
@@ -263,8 +264,8 @@ public void testHoldsLockOnAllOperations() {
     create().add("foo");
     create().addAll(ImmutableList.of("foo"));
     create().clear();
-    boolean unused = create().contains("foo");
-    boolean unused2 = create().containsAll(ImmutableList.of("foo"));
+    create().contains("foo");
+    create().containsAll(ImmutableList.of("foo"));
     create().equals(new ArrayDeque<>(ImmutableList.of("foo")));
     create().hashCode();
     create().isEmpty();
diff --git a/guava-tests/test/com/google/common/collect/SynchronizedMapTest.java b/guava-tests/test/com/google/common/collect/SynchronizedMapTest.java
index 34d1c6f4a067..2e15eda327a5 100644
--- a/guava-tests/test/com/google/common/collect/SynchronizedMapTest.java
+++ b/guava-tests/test/com/google/common/collect/SynchronizedMapTest.java
@@ -159,11 +159,11 @@ public String toString() {
    */
 
   public void testSize() {
-    create().size();
+    int unused = create().size();
   }
 
   public void testIsEmpty() {
-    create().isEmpty();
+    boolean unused = create().isEmpty();
   }
 
   public void testRemove() {
@@ -216,15 +216,15 @@ public void testEntrySet() {
   }
 
   public void testEquals() {
-    create().equals(new HashMap<String, Integer>());
+    boolean unused = create().equals(new HashMap<String, Integer>());
   }
 
   public void testHashCode() {
-    create().hashCode();
+    int unused = create().hashCode();
   }
 
   public void testToString() {
-    create().toString();
+    String unused = create().toString();
   }
 
   public void testSerialization() {
diff --git a/guava-tests/test/com/google/common/collect/SynchronizedQueueTest.java b/guava-tests/test/com/google/common/collect/SynchronizedQueueTest.java
index ac488462d0ec..1e2290d883be 100644
--- a/guava-tests/test/com/google/common/collect/SynchronizedQueueTest.java
+++ b/guava-tests/test/com/google/common/collect/SynchronizedQueueTest.java
@@ -153,6 +153,7 @@ public <T> T[] toArray(T[] array) {
     private static final long serialVersionUID = 0;
   }
 
+  @SuppressWarnings("CheckReturnValue")
   public void testHoldsLockOnAllOperations() {
     create().element();
     create().offer("foo");
@@ -162,8 +163,8 @@ public void testHoldsLockOnAllOperations() {
     create().add("foo");
     create().addAll(ImmutableList.of("foo"));
     create().clear();
-    boolean unused = create().contains("foo");
-    boolean unused2 = create().containsAll(ImmutableList.of("foo"));
+    create().contains("foo");
+    create().containsAll(ImmutableList.of("foo"));
     create().equals(new ArrayDeque<>(ImmutableList.of("foo")));
     create().hashCode();
     create().isEmpty();
diff --git a/guava-tests/test/com/google/common/collect/TableCollectorsTest.java b/guava-tests/test/com/google/common/collect/TableCollectorsTest.java
index 98b70749857d..9a1fe5bc5358 100644
--- a/guava-tests/test/com/google/common/collect/TableCollectorsTest.java
+++ b/guava-tests/test/com/google/common/collect/TableCollectorsTest.java
@@ -31,252 +31,231 @@
 
 /** Unit tests for {@link TableCollectors}. */
 @GwtCompatible(emulated = true)
-public class TableCollectorsTest {
+public class TableCollectorsTest extends TestCase {
+  public void testToImmutableTable() {
+    Collector<Cell<String, String, Integer>, ?, ImmutableTable<String, String, Integer>> collector =
+        TableCollectors.toImmutableTable(Cell::getRowKey, Cell::getColumnKey, Cell::getValue);
+    BiPredicate<ImmutableTable<String, String, Integer>, ImmutableTable<String, String, Integer>>
+        equivalence = pairwiseOnResultOf(ImmutableTable::cellSet);
+    CollectorTester.of(collector, equivalence)
+        .expectCollects(
+            new ImmutableTable.Builder<String, String, Integer>()
+                .put("one", "uno", 1)
+                .put("two", "dos", 2)
+                .put("three", "tres", 3)
+                .build(),
+            immutableCell("one", "uno", 1),
+            immutableCell("two", "dos", 2),
+            immutableCell("three", "tres", 3));
+  }
 
-  public static final class ToImmutableTableTest extends TestCase {
-    public void testToImmutableTable() {
-      Collector<Cell<String, String, Integer>, ?, ImmutableTable<String, String, Integer>>
-          collector =
-              TableCollectors.toImmutableTable(Cell::getRowKey, Cell::getColumnKey, Cell::getValue);
-      BiPredicate<ImmutableTable<String, String, Integer>, ImmutableTable<String, String, Integer>>
-          equivalence = pairwiseOnResultOf(ImmutableTable::cellSet);
-      CollectorTester.of(collector, equivalence)
-          .expectCollects(
-              new ImmutableTable.Builder<String, String, Integer>()
-                  .put("one", "uno", 1)
-                  .put("two", "dos", 2)
-                  .put("three", "tres", 3)
-                  .build(),
-              immutableCell("one", "uno", 1),
-              immutableCell("two", "dos", 2),
-              immutableCell("three", "tres", 3));
+  public void testToImmutableTableConflict() {
+    Collector<Cell<String, String, Integer>, ?, ImmutableTable<String, String, Integer>> collector =
+        TableCollectors.toImmutableTable(Cell::getRowKey, Cell::getColumnKey, Cell::getValue);
+    try {
+      Stream.of(immutableCell("one", "uno", 1), immutableCell("one", "uno", 2)).collect(collector);
+      fail("Expected IllegalArgumentException");
+    } catch (IllegalArgumentException expected) {
     }
+  }
 
-    public void testToImmutableTableConflict() {
-      Collector<Cell<String, String, Integer>, ?, ImmutableTable<String, String, Integer>>
-          collector =
-              TableCollectors.toImmutableTable(Cell::getRowKey, Cell::getColumnKey, Cell::getValue);
-      try {
-        Stream.of(immutableCell("one", "uno", 1), immutableCell("one", "uno", 2))
-            .collect(collector);
-        fail("Expected IllegalArgumentException");
-      } catch (IllegalArgumentException expected) {
-      }
+  public void testToImmutableTableNullRowKey() {
+    Collector<Cell<String, String, Integer>, ?, ImmutableTable<String, String, Integer>> collector =
+        TableCollectors.toImmutableTable(t -> null, Cell::getColumnKey, Cell::getValue);
+    try {
+      Stream.of(immutableCell("one", "uno", 1)).collect(collector);
+      fail("Expected NullPointerException");
+    } catch (NullPointerException expected) {
     }
+  }
 
-    public void testToImmutableTableNullRowKey() {
-      Collector<Cell<String, String, Integer>, ?, ImmutableTable<String, String, Integer>>
-          collector =
-              TableCollectors.toImmutableTable(t -> null, Cell::getColumnKey, Cell::getValue);
-      try {
-        Stream.of(immutableCell("one", "uno", 1)).collect(collector);
-        fail("Expected NullPointerException");
-      } catch (NullPointerException expected) {
-      }
+  public void testToImmutableTableNullColumnKey() {
+    Collector<Cell<String, String, Integer>, ?, ImmutableTable<String, String, Integer>> collector =
+        TableCollectors.toImmutableTable(Cell::getRowKey, t -> null, Cell::getValue);
+    try {
+      Stream.of(immutableCell("one", "uno", 1)).collect(collector);
+      fail("Expected NullPointerException");
+    } catch (NullPointerException expected) {
     }
+  }
 
-    public void testToImmutableTableNullColumnKey() {
-      Collector<Cell<String, String, Integer>, ?, ImmutableTable<String, String, Integer>>
-          collector = TableCollectors.toImmutableTable(Cell::getRowKey, t -> null, Cell::getValue);
-      try {
-        Stream.of(immutableCell("one", "uno", 1)).collect(collector);
-        fail("Expected NullPointerException");
-      } catch (NullPointerException expected) {
-      }
+  public void testToImmutableTableNullValue() {
+    Collector<Cell<String, String, Integer>, ?, ImmutableTable<String, String, Integer>> collector =
+        TableCollectors.toImmutableTable(Cell::getRowKey, Cell::getColumnKey, t -> null);
+    try {
+      Stream.of(immutableCell("one", "uno", 1)).collect(collector);
+      fail("Expected NullPointerException");
+    } catch (NullPointerException expected) {
     }
-
-    public void testToImmutableTableNullValue() {
-      Collector<Cell<String, String, Integer>, ?, ImmutableTable<String, String, Integer>>
-          collector =
-              TableCollectors.toImmutableTable(Cell::getRowKey, Cell::getColumnKey, t -> null);
-      try {
-        Stream.of(immutableCell("one", "uno", 1)).collect(collector);
-        fail("Expected NullPointerException");
-      } catch (NullPointerException expected) {
-      }
-      collector =
-          TableCollectors.toImmutableTable(Cell::getRowKey, Cell::getColumnKey, Cell::getValue);
-      try {
-        Stream.of(immutableCell("one", "uno", 1), immutableCell("one", "uno", (Integer) null))
-            .collect(collector);
-        fail("Expected NullPointerException");
-      } catch (NullPointerException expected) {
-      }
+    collector =
+        TableCollectors.toImmutableTable(Cell::getRowKey, Cell::getColumnKey, Cell::getValue);
+    try {
+      Stream.of(immutableCell("one", "uno", 1), immutableCell("one", "uno", (Integer) null))
+          .collect(collector);
+      fail("Expected NullPointerException");
+    } catch (NullPointerException expected) {
     }
+  }
 
-    public void testToImmutableTableMerging() {
-      Collector<Cell<String, String, Integer>, ?, ImmutableTable<String, String, Integer>>
-          collector =
-              TableCollectors.toImmutableTable(
-                  Cell::getRowKey, Cell::getColumnKey, Cell::getValue, Integer::sum);
-      BiPredicate<ImmutableTable<String, String, Integer>, ImmutableTable<String, String, Integer>>
-          equivalence = pairwiseOnResultOf(ImmutableTable::cellSet);
-      CollectorTester.of(collector, equivalence)
-          .expectCollects(
-              new ImmutableTable.Builder<String, String, Integer>()
-                  .put("one", "uno", 1)
-                  .put("two", "dos", 6)
-                  .put("three", "tres", 3)
-                  .build(),
-              immutableCell("one", "uno", 1),
-              immutableCell("two", "dos", 2),
-              immutableCell("three", "tres", 3),
-              immutableCell("two", "dos", 4));
-    }
+  public void testToImmutableTableMerging() {
+    Collector<Cell<String, String, Integer>, ?, ImmutableTable<String, String, Integer>> collector =
+        TableCollectors.toImmutableTable(
+            Cell::getRowKey, Cell::getColumnKey, Cell::getValue, Integer::sum);
+    BiPredicate<ImmutableTable<String, String, Integer>, ImmutableTable<String, String, Integer>>
+        equivalence = pairwiseOnResultOf(ImmutableTable::cellSet);
+    CollectorTester.of(collector, equivalence)
+        .expectCollects(
+            new ImmutableTable.Builder<String, String, Integer>()
+                .put("one", "uno", 1)
+                .put("two", "dos", 6)
+                .put("three", "tres", 3)
+                .build(),
+            immutableCell("one", "uno", 1),
+            immutableCell("two", "dos", 2),
+            immutableCell("three", "tres", 3),
+            immutableCell("two", "dos", 4));
+  }
 
-    public void testToImmutableTableMergingNullRowKey() {
-      Collector<Cell<String, String, Integer>, ?, ImmutableTable<String, String, Integer>>
-          collector =
-              TableCollectors.toImmutableTable(
-                  t -> null, Cell::getColumnKey, Cell::getValue, Integer::sum);
-      try {
-        Stream.of(immutableCell("one", "uno", 1)).collect(collector);
-        fail("Expected NullPointerException");
-      } catch (NullPointerException expected) {
-      }
+  public void testToImmutableTableMergingNullRowKey() {
+    Collector<Cell<String, String, Integer>, ?, ImmutableTable<String, String, Integer>> collector =
+        TableCollectors.toImmutableTable(
+            t -> null, Cell::getColumnKey, Cell::getValue, Integer::sum);
+    try {
+      Stream.of(immutableCell("one", "uno", 1)).collect(collector);
+      fail("Expected NullPointerException");
+    } catch (NullPointerException expected) {
     }
+  }
 
-    public void testToImmutableTableMergingNullColumnKey() {
-      Collector<Cell<String, String, Integer>, ?, ImmutableTable<String, String, Integer>>
-          collector =
-              TableCollectors.toImmutableTable(
-                  Cell::getRowKey, t -> null, Cell::getValue, Integer::sum);
-      try {
-        Stream.of(immutableCell("one", "uno", 1)).collect(collector);
-        fail("Expected NullPointerException");
-      } catch (NullPointerException expected) {
-      }
+  public void testToImmutableTableMergingNullColumnKey() {
+    Collector<Cell<String, String, Integer>, ?, ImmutableTable<String, String, Integer>> collector =
+        TableCollectors.toImmutableTable(Cell::getRowKey, t -> null, Cell::getValue, Integer::sum);
+    try {
+      Stream.of(immutableCell("one", "uno", 1)).collect(collector);
+      fail("Expected NullPointerException");
+    } catch (NullPointerException expected) {
     }
+  }
 
-    public void testToImmutableTableMergingNullValue() {
-      Collector<Cell<String, String, Integer>, ?, ImmutableTable<String, String, Integer>>
-          collector =
-              TableCollectors.toImmutableTable(
-                  Cell::getRowKey, Cell::getColumnKey, t -> null, Integer::sum);
-      try {
-        Stream.of(immutableCell("one", "uno", 1)).collect(collector);
-        fail("Expected NullPointerException");
-      } catch (NullPointerException expected) {
-      }
-      collector =
-          TableCollectors.toImmutableTable(
-              Cell::getRowKey,
-              Cell::getColumnKey,
-              Cell::getValue,
-              (i, j) -> MoreObjects.firstNonNull(i, 0) + MoreObjects.firstNonNull(j, 0));
-      try {
-        Stream.of(immutableCell("one", "uno", 1), immutableCell("one", "uno", (Integer) null))
-            .collect(collector);
-        fail("Expected NullPointerException");
-      } catch (NullPointerException expected) {
-      }
+  public void testToImmutableTableMergingNullValue() {
+    Collector<Cell<String, String, Integer>, ?, ImmutableTable<String, String, Integer>> collector =
+        TableCollectors.toImmutableTable(
+            Cell::getRowKey, Cell::getColumnKey, t -> null, Integer::sum);
+    try {
+      Stream.of(immutableCell("one", "uno", 1)).collect(collector);
+      fail("Expected NullPointerException");
+    } catch (NullPointerException expected) {
     }
-
-    public void testToImmutableTableMergingNullMerge() {
-      Collector<Cell<String, String, Integer>, ?, ImmutableTable<String, String, Integer>>
-          collector =
-              TableCollectors.toImmutableTable(
-                  Cell::getRowKey, Cell::getColumnKey, Cell::getValue, (v1, v2) -> null);
-      try {
-        Stream.of(immutableCell("one", "uno", 1), immutableCell("one", "uno", 2))
-            .collect(collector);
-        fail("Expected NullPointerException");
-      } catch (NullPointerException expected) {
-      }
+    collector =
+        TableCollectors.toImmutableTable(
+            Cell::getRowKey,
+            Cell::getColumnKey,
+            Cell::getValue,
+            (i, j) -> MoreObjects.firstNonNull(i, 0) + MoreObjects.firstNonNull(j, 0));
+    try {
+      Stream.of(immutableCell("one", "uno", 1), immutableCell("one", "uno", (Integer) null))
+          .collect(collector);
+      fail("Expected NullPointerException");
+    } catch (NullPointerException expected) {
     }
   }
 
-  public static final class ToTableTest extends TestCase {
-
-    public void testToTable() {
-      Collector<Cell<String, String, Integer>, ?, Table<String, String, Integer>> collector =
-          TableCollectors.toTable(
-              Cell::getRowKey, Cell::getColumnKey, Cell::getValue, HashBasedTable::create);
-      BiPredicate<Table<String, String, Integer>, Table<String, String, Integer>> equivalence =
-          pairwiseOnResultOf(Table::cellSet);
-      CollectorTester.of(collector, equivalence)
-          .expectCollects(
-              new ImmutableTable.Builder<String, String, Integer>()
-                  .put("one", "uno", 1)
-                  .put("two", "dos", 2)
-                  .put("three", "tres", 3)
-                  .build(),
-              immutableCell("one", "uno", 1),
-              immutableCell("two", "dos", 2),
-              immutableCell("three", "tres", 3));
+  public void testToImmutableTableMergingNullMerge() {
+    Collector<Cell<String, String, Integer>, ?, ImmutableTable<String, String, Integer>> collector =
+        TableCollectors.toImmutableTable(
+            Cell::getRowKey, Cell::getColumnKey, Cell::getValue, (v1, v2) -> null);
+    try {
+      Stream.of(immutableCell("one", "uno", 1), immutableCell("one", "uno", 2)).collect(collector);
+      fail("Expected NullPointerException");
+    } catch (NullPointerException expected) {
     }
+  }
 
-    public void testToTableNullMerge() {
-      Collector<Cell<String, String, Integer>, ?, Table<String, String, Integer>> collector =
-          TableCollectors.toTable(
-              Cell::getRowKey,
-              Cell::getColumnKey,
-              Cell::getValue,
-              (Integer v1, Integer v2) -> null,
-              HashBasedTable::create);
-      BiPredicate<Table<String, String, Integer>, Table<String, String, Integer>> equivalence =
-          pairwiseOnResultOf(Table::cellSet);
-      CollectorTester.of(collector, equivalence)
-          .expectCollects(
-              ImmutableTable.of(), immutableCell("one", "uno", 1), immutableCell("one", "uno", 2));
-    }
+  public void testToTable() {
+    Collector<Cell<String, String, Integer>, ?, Table<String, String, Integer>> collector =
+        TableCollectors.toTable(
+            Cell::getRowKey, Cell::getColumnKey, Cell::getValue, HashBasedTable::create);
+    BiPredicate<Table<String, String, Integer>, Table<String, String, Integer>> equivalence =
+        pairwiseOnResultOf(Table::cellSet);
+    CollectorTester.of(collector, equivalence)
+        .expectCollects(
+            new ImmutableTable.Builder<String, String, Integer>()
+                .put("one", "uno", 1)
+                .put("two", "dos", 2)
+                .put("three", "tres", 3)
+                .build(),
+            immutableCell("one", "uno", 1),
+            immutableCell("two", "dos", 2),
+            immutableCell("three", "tres", 3));
+  }
 
-    public void testToTableNullValues() {
-      Collector<Cell<String, String, Integer>, ?, Table<String, String, Integer>> collector =
-          TableCollectors.toTable(
-              Cell::getRowKey,
-              Cell::getColumnKey,
-              Cell::getValue,
-              () -> ArrayTable.create(ImmutableList.of("one"), ImmutableList.of("uno")));
-      try {
-        Stream.of(immutableCell("one", "uno", (Integer) null)).collect(collector);
-        fail("Expected NullPointerException");
-      } catch (NullPointerException expected) {
-      }
-    }
+  public void testToTableNullMerge() {
+    Collector<Cell<String, String, Integer>, ?, Table<String, String, Integer>> collector =
+        TableCollectors.toTable(
+            Cell::getRowKey,
+            Cell::getColumnKey,
+            Cell::getValue,
+            (Integer v1, Integer v2) -> null,
+            HashBasedTable::create);
+    BiPredicate<Table<String, String, Integer>, Table<String, String, Integer>> equivalence =
+        pairwiseOnResultOf(Table::cellSet);
+    CollectorTester.of(collector, equivalence)
+        .expectCollects(
+            ImmutableTable.of(), immutableCell("one", "uno", 1), immutableCell("one", "uno", 2));
+  }
 
-    public void testToTableConflict() {
-      Collector<Cell<String, String, Integer>, ?, Table<String, String, Integer>> collector =
-          TableCollectors.toTable(
-              Cell::getRowKey, Cell::getColumnKey, Cell::getValue, HashBasedTable::create);
-      try {
-        Stream.of(immutableCell("one", "uno", 1), immutableCell("one", "uno", 2))
-            .collect(collector);
-        fail("Expected IllegalStateException");
-      } catch (IllegalStateException expected) {
-      }
+  public void testToTableNullValues() {
+    Collector<Cell<String, String, Integer>, ?, Table<String, String, Integer>> collector =
+        TableCollectors.toTable(
+            Cell::getRowKey,
+            Cell::getColumnKey,
+            Cell::getValue,
+            () -> ArrayTable.create(ImmutableList.of("one"), ImmutableList.of("uno")));
+    try {
+      Stream.of(immutableCell("one", "uno", (Integer) null)).collect(collector);
+      fail("Expected NullPointerException");
+    } catch (NullPointerException expected) {
     }
+  }
 
-    public void testToTableMerging() {
-      Collector<Cell<String, String, Integer>, ?, Table<String, String, Integer>> collector =
-          TableCollectors.toTable(
-              Cell::getRowKey,
-              Cell::getColumnKey,
-              Cell::getValue,
-              Integer::sum,
-              HashBasedTable::create);
-      BiPredicate<Table<String, String, Integer>, Table<String, String, Integer>> equivalence =
-          pairwiseOnResultOf(Table::cellSet);
-      CollectorTester.of(collector, equivalence)
-          .expectCollects(
-              new ImmutableTable.Builder<String, String, Integer>()
-                  .put("one", "uno", 1)
-                  .put("two", "dos", 6)
-                  .put("three", "tres", 3)
-                  .build(),
-              immutableCell("one", "uno", 1),
-              immutableCell("two", "dos", 2),
-              immutableCell("three", "tres", 3),
-              immutableCell("two", "dos", 4));
+  public void testToTableConflict() {
+    Collector<Cell<String, String, Integer>, ?, Table<String, String, Integer>> collector =
+        TableCollectors.toTable(
+            Cell::getRowKey, Cell::getColumnKey, Cell::getValue, HashBasedTable::create);
+    try {
+      Stream.of(immutableCell("one", "uno", 1), immutableCell("one", "uno", 2)).collect(collector);
+      fail("Expected IllegalStateException");
+    } catch (IllegalStateException expected) {
     }
   }
 
+  public void testToTableMerging() {
+    Collector<Cell<String, String, Integer>, ?, Table<String, String, Integer>> collector =
+        TableCollectors.toTable(
+            Cell::getRowKey,
+            Cell::getColumnKey,
+            Cell::getValue,
+            Integer::sum,
+            HashBasedTable::create);
+    BiPredicate<Table<String, String, Integer>, Table<String, String, Integer>> equivalence =
+        pairwiseOnResultOf(Table::cellSet);
+    CollectorTester.of(collector, equivalence)
+        .expectCollects(
+            new ImmutableTable.Builder<String, String, Integer>()
+                .put("one", "uno", 1)
+                .put("two", "dos", 6)
+                .put("three", "tres", 3)
+                .build(),
+            immutableCell("one", "uno", 1),
+            immutableCell("two", "dos", 2),
+            immutableCell("three", "tres", 3),
+            immutableCell("two", "dos", 4));
+  }
+
   // This function specifically returns a BiPredicate, because Guava7’s Equivalence class does not
   // actually implement BiPredicate, and CollectorTests expects a BiPredicate.
   static <C, E, R extends Iterable<E>> BiPredicate<C, C> pairwiseOnResultOf(Function<C, R> arg) {
     Equivalence<C> equivalence = Equivalence.equals().<E>pairwise().onResultOf(arg);
     return equivalence::equivalent;
   }
-
-  private TableCollectorsTest() {}
 }
diff --git a/guava-tests/test/com/google/common/collect/TopKSelectorTest.java b/guava-tests/test/com/google/common/collect/TopKSelectorTest.java
index e21f81703c30..2cebdc338b08 100644
--- a/guava-tests/test/com/google/common/collect/TopKSelectorTest.java
+++ b/guava-tests/test/com/google/common/collect/TopKSelectorTest.java
@@ -18,6 +18,7 @@
 
 import static com.google.common.truth.Truth.assertThat;
 
+import com.google.common.annotations.GwtCompatible;
 import com.google.common.math.IntMath;
 import com.google.common.primitives.Ints;
 import java.math.RoundingMode;
@@ -31,6 +32,7 @@
  *
  * @author Louis Wasserman
  */
+@GwtCompatible
 public class TopKSelectorTest extends TestCase {
 
   public void testNegativeK() {
@@ -119,4 +121,13 @@ public int compare(Integer o1, Integer o2) {
     assertThat(top.topK()).containsExactlyElementsIn(Collections.nCopies(k, 0));
     assertThat(compareCalls[0]).isAtMost(10L * n * IntMath.log2(k, RoundingMode.CEILING));
   }
+
+  public void testExceedMaxIteration() {
+    /*
+     * Bug #5692 occurred when TopKSelector called Arrays.sort incorrectly.
+     */
+    TopKSelector<Integer> top = TopKSelector.least(7);
+    top.offerAll(Ints.asList(5, 7, 6, 2, 4, 3, 1, 0, 0, 0, 0, 0, 0, 0));
+    assertThat(top.topK()).isEqualTo(Ints.asList(0, 0, 0, 0, 0, 0, 0));
+  }
 }
diff --git a/guava-tests/test/com/google/common/collect/UnmodifiableIteratorTest.java b/guava-tests/test/com/google/common/collect/UnmodifiableIteratorTest.java
index 77ecbf730362..5e474aa70f67 100644
--- a/guava-tests/test/com/google/common/collect/UnmodifiableIteratorTest.java
+++ b/guava-tests/test/com/google/common/collect/UnmodifiableIteratorTest.java
@@ -29,6 +29,7 @@
 @GwtCompatible
 public class UnmodifiableIteratorTest extends TestCase {
 
+  @SuppressWarnings("DoNotCall")
   public void testRemove() {
     final String[] array = {"a", "b", "c"};
 
diff --git a/guava-tests/test/com/google/common/collect/UnmodifiableListIteratorTest.java b/guava-tests/test/com/google/common/collect/UnmodifiableListIteratorTest.java
index c9d3068e0773..36a017d45cb3 100644
--- a/guava-tests/test/com/google/common/collect/UnmodifiableListIteratorTest.java
+++ b/guava-tests/test/com/google/common/collect/UnmodifiableListIteratorTest.java
@@ -29,6 +29,7 @@
  */
 @GwtCompatible
 public class UnmodifiableListIteratorTest extends TestCase {
+  @SuppressWarnings("DoNotCall")
   public void testRemove() {
     Iterator<String> iterator = create();
 
@@ -41,6 +42,7 @@ public void testRemove() {
     }
   }
 
+  @SuppressWarnings("DoNotCall")
   public void testAdd() {
     ListIterator<String> iterator = create();
 
@@ -55,6 +57,7 @@ public void testAdd() {
     }
   }
 
+  @SuppressWarnings("DoNotCall")
   public void testSet() {
     ListIterator<String> iterator = create();
 
diff --git a/guava-tests/test/com/google/common/escape/EscapersTest.java b/guava-tests/test/com/google/common/escape/EscapersTest.java
index 245560af61d5..442232030e0d 100644
--- a/guava-tests/test/com/google/common/escape/EscapersTest.java
+++ b/guava-tests/test/com/google/common/escape/EscapersTest.java
@@ -85,7 +85,7 @@ public void testAsUnicodeEscaper() throws IOException {
                 .put('x', "<hello>".toCharArray())
                 .put('\uD800', "<hi>".toCharArray())
                 .put('\uDC00', "<lo>".toCharArray())
-                .build());
+                .buildOrThrow());
     UnicodeEscaper unicodeEscaper = Escapers.asUnicodeEscaper(charEscaper);
     EscaperAsserts.assertBasic(unicodeEscaper);
     assertEquals("<hello><hi><lo>", charEscaper.escape("x\uD800\uDC00"));
diff --git a/guava-tests/test/com/google/common/eventbus/outside/AbstractEventBusTest.java b/guava-tests/test/com/google/common/eventbus/outside/AbstractEventBusTest.java
new file mode 100644
index 000000000000..f4af7a7516de
--- /dev/null
+++ b/guava-tests/test/com/google/common/eventbus/outside/AbstractEventBusTest.java
@@ -0,0 +1,55 @@
+/*
+ * Copyright (C) 2012 The Guava Authors
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package com.google.common.eventbus.outside;
+
+import com.google.common.eventbus.EventBus;
+import junit.framework.TestCase;
+
+/**
+ * Abstract base class for tests that EventBus finds the correct subscribers.
+ *
+ * <p>The actual tests are distributed among the other classes in this package based on whether they
+ * are annotated or abstract in the superclass.
+ *
+ * <p>This test must be outside the c.g.c.eventbus package to test correctly.
+ *
+ * @author Louis Wasserman
+ */
+abstract class AbstractEventBusTest<H> extends TestCase {
+  static final Object EVENT = new Object();
+
+  abstract H createSubscriber();
+
+  private H subscriber;
+
+  H getSubscriber() {
+    return subscriber;
+  }
+
+  @Override
+  protected void setUp() throws Exception {
+    subscriber = createSubscriber();
+    EventBus bus = new EventBus();
+    bus.register(subscriber);
+    bus.post(EVENT);
+  }
+
+  @Override
+  protected void tearDown() throws Exception {
+    subscriber = null;
+  }
+}
diff --git a/guava-tests/test/com/google/common/eventbus/outside/AbstractNotAnnotatedInSuperclassTest.java b/guava-tests/test/com/google/common/eventbus/outside/AbstractNotAnnotatedInSuperclassTest.java
new file mode 100644
index 000000000000..a391fcbad687
--- /dev/null
+++ b/guava-tests/test/com/google/common/eventbus/outside/AbstractNotAnnotatedInSuperclassTest.java
@@ -0,0 +1,61 @@
+/*
+ * Copyright (C) 2012 The Guava Authors
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package com.google.common.eventbus.outside;
+
+import static com.google.common.truth.Truth.assertThat;
+
+import com.google.common.collect.Lists;
+import com.google.common.eventbus.Subscribe;
+import com.google.common.eventbus.outside.AbstractNotAnnotatedInSuperclassTest.SubClass;
+import java.util.List;
+
+public class AbstractNotAnnotatedInSuperclassTest extends AbstractEventBusTest<SubClass> {
+  abstract static class SuperClass {
+    public abstract void overriddenInSubclassNowhereAnnotated(Object o);
+
+    public abstract void overriddenAndAnnotatedInSubclass(Object o);
+  }
+
+  static class SubClass extends SuperClass {
+    final List<Object> overriddenInSubclassNowhereAnnotatedEvents = Lists.newArrayList();
+    final List<Object> overriddenAndAnnotatedInSubclassEvents = Lists.newArrayList();
+
+    @Override
+    public void overriddenInSubclassNowhereAnnotated(Object o) {
+      overriddenInSubclassNowhereAnnotatedEvents.add(o);
+    }
+
+    @Subscribe
+    @Override
+    public void overriddenAndAnnotatedInSubclass(Object o) {
+      overriddenAndAnnotatedInSubclassEvents.add(o);
+    }
+  }
+
+  public void testOverriddenAndAnnotatedInSubclass() {
+    assertThat(getSubscriber().overriddenAndAnnotatedInSubclassEvents).contains(EVENT);
+  }
+
+  public void testOverriddenInSubclassNowhereAnnotated() {
+    assertThat(getSubscriber().overriddenInSubclassNowhereAnnotatedEvents).isEmpty();
+  }
+
+  @Override
+  SubClass createSubscriber() {
+    return new SubClass();
+  }
+}
diff --git a/guava-tests/test/com/google/common/eventbus/outside/AnnotatedAndAbstractInSuperclassTest.java b/guava-tests/test/com/google/common/eventbus/outside/AnnotatedAndAbstractInSuperclassTest.java
new file mode 100644
index 000000000000..aea17c3b41e7
--- /dev/null
+++ b/guava-tests/test/com/google/common/eventbus/outside/AnnotatedAndAbstractInSuperclassTest.java
@@ -0,0 +1,63 @@
+/*
+ * Copyright (C) 2012 The Guava Authors
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package com.google.common.eventbus.outside;
+
+import static com.google.common.truth.Truth.assertThat;
+
+import com.google.common.collect.Lists;
+import com.google.common.eventbus.Subscribe;
+import com.google.common.eventbus.outside.AnnotatedAndAbstractInSuperclassTest.SubClass;
+import java.util.List;
+
+public class AnnotatedAndAbstractInSuperclassTest extends AbstractEventBusTest<SubClass> {
+  abstract static class SuperClass {
+    @Subscribe
+    public abstract void overriddenAndAnnotatedInSubclass(Object o);
+
+    @Subscribe
+    public abstract void overriddenInSubclass(Object o);
+  }
+
+  static class SubClass extends SuperClass {
+    final List<Object> overriddenAndAnnotatedInSubclassEvents = Lists.newArrayList();
+    final List<Object> overriddenInSubclassEvents = Lists.newArrayList();
+
+    @Subscribe
+    @Override
+    public void overriddenAndAnnotatedInSubclass(Object o) {
+      overriddenAndAnnotatedInSubclassEvents.add(o);
+    }
+
+    @Override
+    public void overriddenInSubclass(Object o) {
+      overriddenInSubclassEvents.add(o);
+    }
+  }
+
+  public void testOverriddenAndAnnotatedInSubclass() {
+    assertThat(getSubscriber().overriddenAndAnnotatedInSubclassEvents).contains(EVENT);
+  }
+
+  public void testOverriddenNotAnnotatedInSubclass() {
+    assertThat(getSubscriber().overriddenInSubclassEvents).contains(EVENT);
+  }
+
+  @Override
+  SubClass createSubscriber() {
+    return new SubClass();
+  }
+}
diff --git a/guava-tests/test/com/google/common/eventbus/outside/AnnotatedNotAbstractInSuperclassTest.java b/guava-tests/test/com/google/common/eventbus/outside/AnnotatedNotAbstractInSuperclassTest.java
new file mode 100644
index 000000000000..3ec8ea4709f9
--- /dev/null
+++ b/guava-tests/test/com/google/common/eventbus/outside/AnnotatedNotAbstractInSuperclassTest.java
@@ -0,0 +1,116 @@
+/*
+ * Copyright (C) 2012 The Guava Authors
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package com.google.common.eventbus.outside;
+
+import static com.google.common.truth.Truth.assertThat;
+
+import com.google.common.collect.Lists;
+import com.google.common.eventbus.Subscribe;
+import com.google.common.eventbus.outside.AnnotatedNotAbstractInSuperclassTest.SubClass;
+import java.util.List;
+
+public class AnnotatedNotAbstractInSuperclassTest extends AbstractEventBusTest<SubClass> {
+  static class SuperClass {
+    final List<Object> notOverriddenInSubclassEvents = Lists.newArrayList();
+    final List<Object> overriddenNotAnnotatedInSubclassEvents = Lists.newArrayList();
+    final List<Object> overriddenAndAnnotatedInSubclassEvents = Lists.newArrayList();
+    final List<Object> differentlyOverriddenNotAnnotatedInSubclassBadEvents = Lists.newArrayList();
+    final List<Object> differentlyOverriddenAnnotatedInSubclassBadEvents = Lists.newArrayList();
+
+    @Subscribe
+    public void notOverriddenInSubclass(Object o) {
+      notOverriddenInSubclassEvents.add(o);
+    }
+
+    @Subscribe
+    public void overriddenNotAnnotatedInSubclass(Object o) {
+      overriddenNotAnnotatedInSubclassEvents.add(o);
+    }
+
+    @Subscribe
+    public void overriddenAndAnnotatedInSubclass(Object o) {
+      overriddenAndAnnotatedInSubclassEvents.add(o);
+    }
+
+    @Subscribe
+    public void differentlyOverriddenNotAnnotatedInSubclass(Object o) {
+      // the subclass overrides this and does *not* call super.dONAIS(o)
+      differentlyOverriddenNotAnnotatedInSubclassBadEvents.add(o);
+    }
+
+    @Subscribe
+    public void differentlyOverriddenAnnotatedInSubclass(Object o) {
+      // the subclass overrides this and does *not* call super.dOAIS(o)
+      differentlyOverriddenAnnotatedInSubclassBadEvents.add(o);
+    }
+  }
+
+  static class SubClass extends SuperClass {
+    final List<Object> differentlyOverriddenNotAnnotatedInSubclassGoodEvents = Lists.newArrayList();
+    final List<Object> differentlyOverriddenAnnotatedInSubclassGoodEvents = Lists.newArrayList();
+
+    @Override
+    public void overriddenNotAnnotatedInSubclass(Object o) {
+      super.overriddenNotAnnotatedInSubclass(o);
+    }
+
+    @Subscribe
+    @Override
+    public void overriddenAndAnnotatedInSubclass(Object o) {
+      super.overriddenAndAnnotatedInSubclass(o);
+    }
+
+    @Override
+    public void differentlyOverriddenNotAnnotatedInSubclass(Object o) {
+      differentlyOverriddenNotAnnotatedInSubclassGoodEvents.add(o);
+    }
+
+    @Subscribe
+    @Override
+    public void differentlyOverriddenAnnotatedInSubclass(Object o) {
+      differentlyOverriddenAnnotatedInSubclassGoodEvents.add(o);
+    }
+  }
+
+  public void testNotOverriddenInSubclass() {
+    assertThat(getSubscriber().notOverriddenInSubclassEvents).contains(EVENT);
+  }
+
+  public void testOverriddenNotAnnotatedInSubclass() {
+    assertThat(getSubscriber().overriddenNotAnnotatedInSubclassEvents).contains(EVENT);
+  }
+
+  public void testDifferentlyOverriddenNotAnnotatedInSubclass() {
+    assertThat(getSubscriber().differentlyOverriddenNotAnnotatedInSubclassGoodEvents)
+        .contains(EVENT);
+    assertThat(getSubscriber().differentlyOverriddenNotAnnotatedInSubclassBadEvents).isEmpty();
+  }
+
+  public void testOverriddenAndAnnotatedInSubclass() {
+    assertThat(getSubscriber().overriddenAndAnnotatedInSubclassEvents).contains(EVENT);
+  }
+
+  public void testDifferentlyOverriddenAndAnnotatedInSubclass() {
+    assertThat(getSubscriber().differentlyOverriddenAnnotatedInSubclassGoodEvents).contains(EVENT);
+    assertThat(getSubscriber().differentlyOverriddenAnnotatedInSubclassBadEvents).isEmpty();
+  }
+
+  @Override
+  SubClass createSubscriber() {
+    return new SubClass();
+  }
+}
diff --git a/guava-tests/test/com/google/common/eventbus/outside/AnnotatedSubscriberFinderTests.java b/guava-tests/test/com/google/common/eventbus/outside/AnnotatedSubscriberFinderTests.java
deleted file mode 100644
index a1cbb594481e..000000000000
--- a/guava-tests/test/com/google/common/eventbus/outside/AnnotatedSubscriberFinderTests.java
+++ /dev/null
@@ -1,448 +0,0 @@
-/*
- * Copyright (C) 2012 The Guava Authors
- *
- * Licensed under the Apache License, Version 2.0 (the "License");
- * you may not use this file except in compliance with the License.
- * You may obtain a copy of the License at
- *
- * http://www.apache.org/licenses/LICENSE-2.0
- *
- * Unless required by applicable law or agreed to in writing, software
- * distributed under the License is distributed on an "AS IS" BASIS,
- * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
- * See the License for the specific language governing permissions and
- * limitations under the License.
- */
-
-package com.google.common.eventbus.outside;
-
-import static com.google.common.truth.Truth.assertThat;
-
-import com.google.common.collect.Lists;
-import com.google.common.eventbus.EventBus;
-import com.google.common.eventbus.Subscribe;
-import java.util.List;
-import junit.framework.TestCase;
-
-/**
- * Test that EventBus finds the correct subscribers.
- *
- * <p>This test must be outside the c.g.c.eventbus package to test correctly.
- *
- * @author Louis Wasserman
- */
-public class AnnotatedSubscriberFinderTests {
-
-  private static final Object EVENT = new Object();
-
-  abstract static class AbstractEventBusTest<H> extends TestCase {
-    abstract H createSubscriber();
-
-    private H subscriber;
-
-    H getSubscriber() {
-      return subscriber;
-    }
-
-    @Override
-    protected void setUp() throws Exception {
-      subscriber = createSubscriber();
-      EventBus bus = new EventBus();
-      bus.register(subscriber);
-      bus.post(EVENT);
-    }
-
-    @Override
-    protected void tearDown() throws Exception {
-      subscriber = null;
-    }
-  }
-
-  /*
-   * We break the tests up based on whether they are annotated or abstract in the superclass.
-   */
-  public static class BaseSubscriberFinderTest
-      extends AbstractEventBusTest<BaseSubscriberFinderTest.Subscriber> {
-    static class Subscriber {
-      final List<Object> nonSubscriberEvents = Lists.newArrayList();
-      final List<Object> subscriberEvents = Lists.newArrayList();
-
-      public void notASubscriber(Object o) {
-        nonSubscriberEvents.add(o);
-      }
-
-      @Subscribe
-      public void subscriber(Object o) {
-        subscriberEvents.add(o);
-      }
-    }
-
-    public void testNonSubscriber() {
-      assertThat(getSubscriber().nonSubscriberEvents).isEmpty();
-    }
-
-    public void testSubscriber() {
-      assertThat(getSubscriber().subscriberEvents).contains(EVENT);
-    }
-
-    @Override
-    Subscriber createSubscriber() {
-      return new Subscriber();
-    }
-  }
-
-  public static class AnnotatedAndAbstractInSuperclassTest
-      extends AbstractEventBusTest<AnnotatedAndAbstractInSuperclassTest.SubClass> {
-    abstract static class SuperClass {
-      @Subscribe
-      public abstract void overriddenAndAnnotatedInSubclass(Object o);
-
-      @Subscribe
-      public abstract void overriddenInSubclass(Object o);
-    }
-
-    static class SubClass extends SuperClass {
-      final List<Object> overriddenAndAnnotatedInSubclassEvents = Lists.newArrayList();
-      final List<Object> overriddenInSubclassEvents = Lists.newArrayList();
-
-      @Subscribe
-      @Override
-      public void overriddenAndAnnotatedInSubclass(Object o) {
-        overriddenAndAnnotatedInSubclassEvents.add(o);
-      }
-
-      @Override
-      public void overriddenInSubclass(Object o) {
-        overriddenInSubclassEvents.add(o);
-      }
-    }
-
-    public void testOverriddenAndAnnotatedInSubclass() {
-      assertThat(getSubscriber().overriddenAndAnnotatedInSubclassEvents).contains(EVENT);
-    }
-
-    public void testOverriddenNotAnnotatedInSubclass() {
-      assertThat(getSubscriber().overriddenInSubclassEvents).contains(EVENT);
-    }
-
-    @Override
-    SubClass createSubscriber() {
-      return new SubClass();
-    }
-  }
-
-  public static class AnnotatedNotAbstractInSuperclassTest
-      extends AbstractEventBusTest<AnnotatedNotAbstractInSuperclassTest.SubClass> {
-    static class SuperClass {
-      final List<Object> notOverriddenInSubclassEvents = Lists.newArrayList();
-      final List<Object> overriddenNotAnnotatedInSubclassEvents = Lists.newArrayList();
-      final List<Object> overriddenAndAnnotatedInSubclassEvents = Lists.newArrayList();
-      final List<Object> differentlyOverriddenNotAnnotatedInSubclassBadEvents =
-          Lists.newArrayList();
-      final List<Object> differentlyOverriddenAnnotatedInSubclassBadEvents = Lists.newArrayList();
-
-      @Subscribe
-      public void notOverriddenInSubclass(Object o) {
-        notOverriddenInSubclassEvents.add(o);
-      }
-
-      @Subscribe
-      public void overriddenNotAnnotatedInSubclass(Object o) {
-        overriddenNotAnnotatedInSubclassEvents.add(o);
-      }
-
-      @Subscribe
-      public void overriddenAndAnnotatedInSubclass(Object o) {
-        overriddenAndAnnotatedInSubclassEvents.add(o);
-      }
-
-      @Subscribe
-      public void differentlyOverriddenNotAnnotatedInSubclass(Object o) {
-        // the subclass overrides this and does *not* call super.dONAIS(o)
-        differentlyOverriddenNotAnnotatedInSubclassBadEvents.add(o);
-      }
-
-      @Subscribe
-      public void differentlyOverriddenAnnotatedInSubclass(Object o) {
-        // the subclass overrides this and does *not* call super.dOAIS(o)
-        differentlyOverriddenAnnotatedInSubclassBadEvents.add(o);
-      }
-    }
-
-    static class SubClass extends SuperClass {
-      final List<Object> differentlyOverriddenNotAnnotatedInSubclassGoodEvents =
-          Lists.newArrayList();
-      final List<Object> differentlyOverriddenAnnotatedInSubclassGoodEvents = Lists.newArrayList();
-
-      @Override
-      public void overriddenNotAnnotatedInSubclass(Object o) {
-        super.overriddenNotAnnotatedInSubclass(o);
-      }
-
-      @Subscribe
-      @Override
-      public void overriddenAndAnnotatedInSubclass(Object o) {
-        super.overriddenAndAnnotatedInSubclass(o);
-      }
-
-      @Override
-      public void differentlyOverriddenNotAnnotatedInSubclass(Object o) {
-        differentlyOverriddenNotAnnotatedInSubclassGoodEvents.add(o);
-      }
-
-      @Subscribe
-      @Override
-      public void differentlyOverriddenAnnotatedInSubclass(Object o) {
-        differentlyOverriddenAnnotatedInSubclassGoodEvents.add(o);
-      }
-    }
-
-    public void testNotOverriddenInSubclass() {
-      assertThat(getSubscriber().notOverriddenInSubclassEvents).contains(EVENT);
-    }
-
-    public void testOverriddenNotAnnotatedInSubclass() {
-      assertThat(getSubscriber().overriddenNotAnnotatedInSubclassEvents).contains(EVENT);
-    }
-
-    public void testDifferentlyOverriddenNotAnnotatedInSubclass() {
-      assertThat(getSubscriber().differentlyOverriddenNotAnnotatedInSubclassGoodEvents)
-          .contains(EVENT);
-      assertThat(getSubscriber().differentlyOverriddenNotAnnotatedInSubclassBadEvents).isEmpty();
-    }
-
-    public void testOverriddenAndAnnotatedInSubclass() {
-      assertThat(getSubscriber().overriddenAndAnnotatedInSubclassEvents).contains(EVENT);
-    }
-
-    public void testDifferentlyOverriddenAndAnnotatedInSubclass() {
-      assertThat(getSubscriber().differentlyOverriddenAnnotatedInSubclassGoodEvents)
-          .contains(EVENT);
-      assertThat(getSubscriber().differentlyOverriddenAnnotatedInSubclassBadEvents).isEmpty();
-    }
-
-    @Override
-    SubClass createSubscriber() {
-      return new SubClass();
-    }
-  }
-
-  public static class AbstractNotAnnotatedInSuperclassTest
-      extends AbstractEventBusTest<AbstractNotAnnotatedInSuperclassTest.SubClass> {
-    abstract static class SuperClass {
-      public abstract void overriddenInSubclassNowhereAnnotated(Object o);
-
-      public abstract void overriddenAndAnnotatedInSubclass(Object o);
-    }
-
-    static class SubClass extends SuperClass {
-      final List<Object> overriddenInSubclassNowhereAnnotatedEvents = Lists.newArrayList();
-      final List<Object> overriddenAndAnnotatedInSubclassEvents = Lists.newArrayList();
-
-      @Override
-      public void overriddenInSubclassNowhereAnnotated(Object o) {
-        overriddenInSubclassNowhereAnnotatedEvents.add(o);
-      }
-
-      @Subscribe
-      @Override
-      public void overriddenAndAnnotatedInSubclass(Object o) {
-        overriddenAndAnnotatedInSubclassEvents.add(o);
-      }
-    }
-
-    public void testOverriddenAndAnnotatedInSubclass() {
-      assertThat(getSubscriber().overriddenAndAnnotatedInSubclassEvents).contains(EVENT);
-    }
-
-    public void testOverriddenInSubclassNowhereAnnotated() {
-      assertThat(getSubscriber().overriddenInSubclassNowhereAnnotatedEvents).isEmpty();
-    }
-
-    @Override
-    SubClass createSubscriber() {
-      return new SubClass();
-    }
-  }
-
-  public static class NeitherAbstractNorAnnotatedInSuperclassTest
-      extends AbstractEventBusTest<NeitherAbstractNorAnnotatedInSuperclassTest.SubClass> {
-    static class SuperClass {
-      final List<Object> neitherOverriddenNorAnnotatedEvents = Lists.newArrayList();
-      final List<Object> overriddenInSubclassNowhereAnnotatedEvents = Lists.newArrayList();
-      final List<Object> overriddenAndAnnotatedInSubclassEvents = Lists.newArrayList();
-
-      public void neitherOverriddenNorAnnotated(Object o) {
-        neitherOverriddenNorAnnotatedEvents.add(o);
-      }
-
-      public void overriddenInSubclassNowhereAnnotated(Object o) {
-        overriddenInSubclassNowhereAnnotatedEvents.add(o);
-      }
-
-      public void overriddenAndAnnotatedInSubclass(Object o) {
-        overriddenAndAnnotatedInSubclassEvents.add(o);
-      }
-    }
-
-    static class SubClass extends SuperClass {
-      @Override
-      public void overriddenInSubclassNowhereAnnotated(Object o) {
-        super.overriddenInSubclassNowhereAnnotated(o);
-      }
-
-      @Subscribe
-      @Override
-      public void overriddenAndAnnotatedInSubclass(Object o) {
-        super.overriddenAndAnnotatedInSubclass(o);
-      }
-    }
-
-    public void testNeitherOverriddenNorAnnotated() {
-      assertThat(getSubscriber().neitherOverriddenNorAnnotatedEvents).isEmpty();
-    }
-
-    public void testOverriddenInSubclassNowhereAnnotated() {
-      assertThat(getSubscriber().overriddenInSubclassNowhereAnnotatedEvents).isEmpty();
-    }
-
-    public void testOverriddenAndAnnotatedInSubclass() {
-      assertThat(getSubscriber().overriddenAndAnnotatedInSubclassEvents).contains(EVENT);
-    }
-
-    @Override
-    SubClass createSubscriber() {
-      return new SubClass();
-    }
-  }
-
-  public static class DeepInterfaceTest
-      extends AbstractEventBusTest<DeepInterfaceTest.SubscriberClass> {
-    interface Interface1 {
-      @Subscribe
-      void annotatedIn1(Object o);
-
-      @Subscribe
-      void annotatedIn1And2(Object o);
-
-      @Subscribe
-      void annotatedIn1And2AndClass(Object o);
-
-      void declaredIn1AnnotatedIn2(Object o);
-
-      void declaredIn1AnnotatedInClass(Object o);
-
-      void nowhereAnnotated(Object o);
-    }
-
-    interface Interface2 extends Interface1 {
-      @Override
-      @Subscribe
-      void declaredIn1AnnotatedIn2(Object o);
-
-      @Override
-      @Subscribe
-      void annotatedIn1And2(Object o);
-
-      @Override
-      @Subscribe
-      void annotatedIn1And2AndClass(Object o);
-
-      void declaredIn2AnnotatedInClass(Object o);
-
-      @Subscribe
-      void annotatedIn2(Object o);
-    }
-
-    static class SubscriberClass implements Interface2 {
-      final List<Object> annotatedIn1Events = Lists.newArrayList();
-      final List<Object> annotatedIn1And2Events = Lists.newArrayList();
-      final List<Object> annotatedIn1And2AndClassEvents = Lists.newArrayList();
-      final List<Object> declaredIn1AnnotatedIn2Events = Lists.newArrayList();
-      final List<Object> declaredIn1AnnotatedInClassEvents = Lists.newArrayList();
-      final List<Object> declaredIn2AnnotatedInClassEvents = Lists.newArrayList();
-      final List<Object> annotatedIn2Events = Lists.newArrayList();
-      final List<Object> nowhereAnnotatedEvents = Lists.newArrayList();
-
-      @Override
-      public void annotatedIn1(Object o) {
-        annotatedIn1Events.add(o);
-      }
-
-      @Subscribe
-      @Override
-      public void declaredIn1AnnotatedInClass(Object o) {
-        declaredIn1AnnotatedInClassEvents.add(o);
-      }
-
-      @Override
-      public void declaredIn1AnnotatedIn2(Object o) {
-        declaredIn1AnnotatedIn2Events.add(o);
-      }
-
-      @Override
-      public void annotatedIn1And2(Object o) {
-        annotatedIn1And2Events.add(o);
-      }
-
-      @Subscribe
-      @Override
-      public void annotatedIn1And2AndClass(Object o) {
-        annotatedIn1And2AndClassEvents.add(o);
-      }
-
-      @Subscribe
-      @Override
-      public void declaredIn2AnnotatedInClass(Object o) {
-        declaredIn2AnnotatedInClassEvents.add(o);
-      }
-
-      @Override
-      public void annotatedIn2(Object o) {
-        annotatedIn2Events.add(o);
-      }
-
-      @Override
-      public void nowhereAnnotated(Object o) {
-        nowhereAnnotatedEvents.add(o);
-      }
-    }
-
-    public void testAnnotatedIn1() {
-      assertThat(getSubscriber().annotatedIn1Events).contains(EVENT);
-    }
-
-    public void testAnnotatedIn2() {
-      assertThat(getSubscriber().annotatedIn2Events).contains(EVENT);
-    }
-
-    public void testAnnotatedIn1And2() {
-      assertThat(getSubscriber().annotatedIn1And2Events).contains(EVENT);
-    }
-
-    public void testAnnotatedIn1And2AndClass() {
-      assertThat(getSubscriber().annotatedIn1And2AndClassEvents).contains(EVENT);
-    }
-
-    public void testDeclaredIn1AnnotatedIn2() {
-      assertThat(getSubscriber().declaredIn1AnnotatedIn2Events).contains(EVENT);
-    }
-
-    public void testDeclaredIn1AnnotatedInClass() {
-      assertThat(getSubscriber().declaredIn1AnnotatedInClassEvents).contains(EVENT);
-    }
-
-    public void testDeclaredIn2AnnotatedInClass() {
-      assertThat(getSubscriber().declaredIn2AnnotatedInClassEvents).contains(EVENT);
-    }
-
-    public void testNowhereAnnotated() {
-      assertThat(getSubscriber().nowhereAnnotatedEvents).isEmpty();
-    }
-
-    @Override
-    SubscriberClass createSubscriber() {
-      return new SubscriberClass();
-    }
-  }
-}
diff --git a/guava-tests/test/com/google/common/eventbus/outside/BaseSubscriberFinderTest.java b/guava-tests/test/com/google/common/eventbus/outside/BaseSubscriberFinderTest.java
new file mode 100644
index 000000000000..461fb795b07d
--- /dev/null
+++ b/guava-tests/test/com/google/common/eventbus/outside/BaseSubscriberFinderTest.java
@@ -0,0 +1,53 @@
+/*
+ * Copyright (C) 2012 The Guava Authors
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package com.google.common.eventbus.outside;
+
+import static com.google.common.truth.Truth.assertThat;
+
+import com.google.common.collect.Lists;
+import com.google.common.eventbus.Subscribe;
+import com.google.common.eventbus.outside.BaseSubscriberFinderTest.Subscriber;
+import java.util.List;
+
+public class BaseSubscriberFinderTest extends AbstractEventBusTest<Subscriber> {
+  static class Subscriber {
+    final List<Object> nonSubscriberEvents = Lists.newArrayList();
+    final List<Object> subscriberEvents = Lists.newArrayList();
+
+    public void notASubscriber(Object o) {
+      nonSubscriberEvents.add(o);
+    }
+
+    @Subscribe
+    public void subscriber(Object o) {
+      subscriberEvents.add(o);
+    }
+  }
+
+  public void testNonSubscriber() {
+    assertThat(getSubscriber().nonSubscriberEvents).isEmpty();
+  }
+
+  public void testSubscriber() {
+    assertThat(getSubscriber().subscriberEvents).contains(EVENT);
+  }
+
+  @Override
+  Subscriber createSubscriber() {
+    return new Subscriber();
+  }
+}
diff --git a/guava-tests/test/com/google/common/eventbus/outside/DeepInterfaceTest.java b/guava-tests/test/com/google/common/eventbus/outside/DeepInterfaceTest.java
new file mode 100644
index 000000000000..4fefbc12ab15
--- /dev/null
+++ b/guava-tests/test/com/google/common/eventbus/outside/DeepInterfaceTest.java
@@ -0,0 +1,153 @@
+/*
+ * Copyright (C) 2012 The Guava Authors
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package com.google.common.eventbus.outside;
+
+import static com.google.common.truth.Truth.assertThat;
+
+import com.google.common.collect.Lists;
+import com.google.common.eventbus.Subscribe;
+import com.google.common.eventbus.outside.DeepInterfaceTest.SubscriberClass;
+import java.util.List;
+
+public class DeepInterfaceTest extends AbstractEventBusTest<SubscriberClass> {
+  interface Interface1 {
+    @Subscribe
+    void annotatedIn1(Object o);
+
+    @Subscribe
+    void annotatedIn1And2(Object o);
+
+    @Subscribe
+    void annotatedIn1And2AndClass(Object o);
+
+    void declaredIn1AnnotatedIn2(Object o);
+
+    void declaredIn1AnnotatedInClass(Object o);
+
+    void nowhereAnnotated(Object o);
+  }
+
+  interface Interface2 extends Interface1 {
+    @Override
+    @Subscribe
+    void declaredIn1AnnotatedIn2(Object o);
+
+    @Override
+    @Subscribe
+    void annotatedIn1And2(Object o);
+
+    @Override
+    @Subscribe
+    void annotatedIn1And2AndClass(Object o);
+
+    void declaredIn2AnnotatedInClass(Object o);
+
+    @Subscribe
+    void annotatedIn2(Object o);
+  }
+
+  static class SubscriberClass implements Interface2 {
+    final List<Object> annotatedIn1Events = Lists.newArrayList();
+    final List<Object> annotatedIn1And2Events = Lists.newArrayList();
+    final List<Object> annotatedIn1And2AndClassEvents = Lists.newArrayList();
+    final List<Object> declaredIn1AnnotatedIn2Events = Lists.newArrayList();
+    final List<Object> declaredIn1AnnotatedInClassEvents = Lists.newArrayList();
+    final List<Object> declaredIn2AnnotatedInClassEvents = Lists.newArrayList();
+    final List<Object> annotatedIn2Events = Lists.newArrayList();
+    final List<Object> nowhereAnnotatedEvents = Lists.newArrayList();
+
+    @Override
+    public void annotatedIn1(Object o) {
+      annotatedIn1Events.add(o);
+    }
+
+    @Subscribe
+    @Override
+    public void declaredIn1AnnotatedInClass(Object o) {
+      declaredIn1AnnotatedInClassEvents.add(o);
+    }
+
+    @Override
+    public void declaredIn1AnnotatedIn2(Object o) {
+      declaredIn1AnnotatedIn2Events.add(o);
+    }
+
+    @Override
+    public void annotatedIn1And2(Object o) {
+      annotatedIn1And2Events.add(o);
+    }
+
+    @Subscribe
+    @Override
+    public void annotatedIn1And2AndClass(Object o) {
+      annotatedIn1And2AndClassEvents.add(o);
+    }
+
+    @Subscribe
+    @Override
+    public void declaredIn2AnnotatedInClass(Object o) {
+      declaredIn2AnnotatedInClassEvents.add(o);
+    }
+
+    @Override
+    public void annotatedIn2(Object o) {
+      annotatedIn2Events.add(o);
+    }
+
+    @Override
+    public void nowhereAnnotated(Object o) {
+      nowhereAnnotatedEvents.add(o);
+    }
+  }
+
+  public void testAnnotatedIn1() {
+    assertThat(getSubscriber().annotatedIn1Events).contains(EVENT);
+  }
+
+  public void testAnnotatedIn2() {
+    assertThat(getSubscriber().annotatedIn2Events).contains(EVENT);
+  }
+
+  public void testAnnotatedIn1And2() {
+    assertThat(getSubscriber().annotatedIn1And2Events).contains(EVENT);
+  }
+
+  public void testAnnotatedIn1And2AndClass() {
+    assertThat(getSubscriber().annotatedIn1And2AndClassEvents).contains(EVENT);
+  }
+
+  public void testDeclaredIn1AnnotatedIn2() {
+    assertThat(getSubscriber().declaredIn1AnnotatedIn2Events).contains(EVENT);
+  }
+
+  public void testDeclaredIn1AnnotatedInClass() {
+    assertThat(getSubscriber().declaredIn1AnnotatedInClassEvents).contains(EVENT);
+  }
+
+  public void testDeclaredIn2AnnotatedInClass() {
+    assertThat(getSubscriber().declaredIn2AnnotatedInClassEvents).contains(EVENT);
+  }
+
+  public void testNowhereAnnotated() {
+    assertThat(getSubscriber().nowhereAnnotatedEvents).isEmpty();
+  }
+
+  @Override
+  SubscriberClass createSubscriber() {
+    return new SubscriberClass();
+  }
+}
diff --git a/guava-tests/test/com/google/common/eventbus/outside/NeitherAbstractNorAnnotatedInSuperclassTest.java b/guava-tests/test/com/google/common/eventbus/outside/NeitherAbstractNorAnnotatedInSuperclassTest.java
new file mode 100644
index 000000000000..a2aca555b499
--- /dev/null
+++ b/guava-tests/test/com/google/common/eventbus/outside/NeitherAbstractNorAnnotatedInSuperclassTest.java
@@ -0,0 +1,74 @@
+/*
+ * Copyright (C) 2012 The Guava Authors
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package com.google.common.eventbus.outside;
+
+import static com.google.common.truth.Truth.assertThat;
+
+import com.google.common.collect.Lists;
+import com.google.common.eventbus.Subscribe;
+import com.google.common.eventbus.outside.NeitherAbstractNorAnnotatedInSuperclassTest.SubClass;
+import java.util.List;
+
+public class NeitherAbstractNorAnnotatedInSuperclassTest extends AbstractEventBusTest<SubClass> {
+  static class SuperClass {
+    final List<Object> neitherOverriddenNorAnnotatedEvents = Lists.newArrayList();
+    final List<Object> overriddenInSubclassNowhereAnnotatedEvents = Lists.newArrayList();
+    final List<Object> overriddenAndAnnotatedInSubclassEvents = Lists.newArrayList();
+
+    public void neitherOverriddenNorAnnotated(Object o) {
+      neitherOverriddenNorAnnotatedEvents.add(o);
+    }
+
+    public void overriddenInSubclassNowhereAnnotated(Object o) {
+      overriddenInSubclassNowhereAnnotatedEvents.add(o);
+    }
+
+    public void overriddenAndAnnotatedInSubclass(Object o) {
+      overriddenAndAnnotatedInSubclassEvents.add(o);
+    }
+  }
+
+  static class SubClass extends SuperClass {
+    @Override
+    public void overriddenInSubclassNowhereAnnotated(Object o) {
+      super.overriddenInSubclassNowhereAnnotated(o);
+    }
+
+    @Subscribe
+    @Override
+    public void overriddenAndAnnotatedInSubclass(Object o) {
+      super.overriddenAndAnnotatedInSubclass(o);
+    }
+  }
+
+  public void testNeitherOverriddenNorAnnotated() {
+    assertThat(getSubscriber().neitherOverriddenNorAnnotatedEvents).isEmpty();
+  }
+
+  public void testOverriddenInSubclassNowhereAnnotated() {
+    assertThat(getSubscriber().overriddenInSubclassNowhereAnnotatedEvents).isEmpty();
+  }
+
+  public void testOverriddenAndAnnotatedInSubclass() {
+    assertThat(getSubscriber().overriddenAndAnnotatedInSubclassEvents).contains(EVENT);
+  }
+
+  @Override
+  SubClass createSubscriber() {
+    return new SubClass();
+  }
+}
diff --git a/guava-tests/test/com/google/common/graph/MapCacheTest.java b/guava-tests/test/com/google/common/graph/MapCacheTest.java
index f66b19b7d985..f04f010c84c9 100644
--- a/guava-tests/test/com/google/common/graph/MapCacheTest.java
+++ b/guava-tests/test/com/google/common/graph/MapCacheTest.java
@@ -90,25 +90,4 @@ public void testRemoveEqualKeyWithDifferentReference() {
     assertThat(mapCache.remove(fooReference2)).isEqualTo("bar");
     assertThat(mapCache.get(fooReference1)).isNull();
   }
-
-  @Test
-  public void testHandleNulls() {
-    mapCache.put("foo", "bar");
-    mapCache.put("non-null key", null);
-    mapCache.put(null, "non-null value");
-
-    assertThat(mapCache.get("foo")).isEqualTo("bar");
-    assertThat(mapCache.get("non-null key")).isNull();
-    assertThat(mapCache.get(null)).isEqualTo("non-null value");
-
-    assertThat(mapCache.containsKey("foo")).isTrue();
-    assertThat(mapCache.containsKey("bar")).isFalse();
-    assertThat(mapCache.containsKey("non-null key")).isTrue();
-    assertThat(mapCache.containsKey(null)).isTrue();
-
-    // Test again - in reverse order.
-    assertThat(mapCache.get(null)).isEqualTo("non-null value");
-    assertThat(mapCache.get("non-null key")).isNull();
-    assertThat(mapCache.get("foo")).isEqualTo("bar");
-  }
 }
diff --git a/guava-tests/test/com/google/common/hash/BloomFilterTest.java b/guava-tests/test/com/google/common/hash/BloomFilterTest.java
index 411e0977e60c..95306661d228 100644
--- a/guava-tests/test/com/google/common/hash/BloomFilterTest.java
+++ b/guava-tests/test/com/google/common/hash/BloomFilterTest.java
@@ -522,7 +522,10 @@ public void testCustomSerialization() throws Exception {
     ByteArrayOutputStream out = new ByteArrayOutputStream();
     bf.writeTo(out);
 
-    assertEquals(bf, BloomFilter.readFrom(new ByteArrayInputStream(out.toByteArray()), funnel));
+    BloomFilter<byte[]> read =
+        BloomFilter.readFrom(new ByteArrayInputStream(out.toByteArray()), funnel);
+    assertThat(read).isEqualTo(bf);
+    assertThat(read.expectedFpp()).isGreaterThan(0);
   }
 
   /**
diff --git a/guava-tests/test/com/google/common/hash/Fingerprint2011Test.java b/guava-tests/test/com/google/common/hash/Fingerprint2011Test.java
new file mode 100644
index 000000000000..effa63291bf1
--- /dev/null
+++ b/guava-tests/test/com/google/common/hash/Fingerprint2011Test.java
@@ -0,0 +1,233 @@
+// Copyright 2011 Google Inc. All Rights Reserved.
+
+package com.google.common.hash;
+
+import static com.google.common.base.Charsets.ISO_8859_1;
+import static com.google.common.base.Charsets.UTF_8;
+import static com.google.common.truth.Truth.assertThat;
+
+import com.google.common.base.Strings;
+import com.google.common.collect.ImmutableSortedMap;
+import com.google.common.collect.Ordering;
+import com.google.common.primitives.UnsignedLong;
+import java.util.Arrays;
+import junit.framework.TestCase;
+
+/**
+ * Unit test for Fingerprint2011.
+ *
+ * @author kylemaddison@google.com (Kyle Maddison)
+ */
+public class Fingerprint2011Test extends TestCase {
+
+  // Length of the sample string to produce
+  private static final int MAX_BYTES = 1000;
+
+  // Map from sample string lengths to the fingerprint
+  private static final ImmutableSortedMap<Integer, Long> LENGTH_FINGERPRINTS =
+      new ImmutableSortedMap.Builder<Integer, Long>(Ordering.natural())
+          .put(1000, 0x433109b33e13e6edL)
+          .put(800, 0x5f2f123bfc815f81L)
+          .put(640, 0x6396fc6a67293cf4L)
+          .put(512, 0x45c01b4934ddbbbeL)
+          .put(409, 0xfcd19b617551db45L)
+          .put(327, 0x4eee69e12854871eL)
+          .put(261, 0xab753446a3bbd532L)
+          .put(208, 0x54242fe06a291c3fL)
+          .put(166, 0x4f7acff7703a635bL)
+          .put(132, 0xa784bd0a1f22cc7fL)
+          .put(105, 0xf19118e187456638L)
+          .put(84, 0x3e2e58f9196abfe5L)
+          .put(67, 0xd38ae3dec0107aeaL)
+          .put(53, 0xea3033885868e10eL)
+          .put(42, 0x1394a146d0d7e04bL)
+          .put(33, 0x9962499315d2e8daL)
+          .put(26, 0x0849f5cfa85489b5L)
+          .put(20, 0x83b395ff19bf2171L)
+          .put(16, 0x9d33dd141bd55d9aL)
+          .put(12, 0x196248eb0b02466aL)
+          .put(9, 0x1cf73a50ff120336L)
+          .put(7, 0xb451c339457dbf51L)
+          .put(5, 0x681982c5e7b74064L)
+          .put(4, 0xc5ce47450ca6c021L)
+          .put(3, 0x9fcc3c3fde4d5ff7L)
+          .put(2, 0x090966a836e5fa4bL)
+          .put(1, 0x8199675ecaa6fe64L)
+          .put(0, 0x23ad7c904aa665e3L)
+          .build();
+  private static final HashFunction HASH_FN = Hashing.fingerprint2011();
+
+  // If this test fails, all bets are off
+  public void testReallySimpleFingerprints() {
+    assertEquals(8473225671271759044L, fingerprint("test".getBytes(UTF_8)));
+    // 32 characters long
+    assertEquals(7345148637025587076L, fingerprint(Strings.repeat("test", 8).getBytes(UTF_8)));
+    // 256 characters long
+    assertEquals(4904844928629814570L, fingerprint(Strings.repeat("test", 64).getBytes(UTF_8)));
+  }
+
+  public void testStringsConsistency() {
+    for (String s : Arrays.asList("", "some", "test", "strings", "to", "try")) {
+      assertEquals(HASH_FN.newHasher().putUnencodedChars(s).hash(), HASH_FN.hashUnencodedChars(s));
+    }
+  }
+
+  public void testUtf8() {
+    char[] charsA = new char[128];
+    char[] charsB = new char[128];
+
+    for (int i = 0; i < charsA.length; i++) {
+      if (i < 100) {
+        charsA[i] = 'a';
+        charsB[i] = 'a';
+      } else {
+        // Both two-byte characters, but must be different
+        charsA[i] = (char) (0x0180 + i);
+        charsB[i] = (char) (0x0280 + i);
+      }
+    }
+
+    String stringA = new String(charsA);
+    String stringB = new String(charsB);
+    assertThat(stringA).isNotEqualTo(stringB);
+    assertThat(HASH_FN.hashUnencodedChars(stringA))
+        .isNotEqualTo(HASH_FN.hashUnencodedChars(stringB));
+    assertThat(fingerprint(stringA.getBytes(UTF_8)))
+        .isNotEqualTo(fingerprint(stringB.getBytes(UTF_8)));
+
+    // ISO 8859-1 only has 0-255 (ubyte) representation so throws away UTF-8 characters
+    // greater than 127 (ie with their top bit set).
+    // Don't attempt to do this in real code.
+    assertEquals(
+        fingerprint(stringA.getBytes(ISO_8859_1)), fingerprint(stringB.getBytes(ISO_8859_1)));
+  }
+
+  public void testMumurHash64() {
+    byte[] bytes = "test".getBytes(UTF_8);
+    assertEquals(
+        1618900948208871284L, Fingerprint2011.murmurHash64WithSeed(bytes, 0, bytes.length, 1));
+
+    bytes = "test test test".getBytes(UTF_8);
+    assertEquals(
+        UnsignedLong.valueOf("12313169684067793560").longValue(),
+        Fingerprint2011.murmurHash64WithSeed(bytes, 0, bytes.length, 1));
+  }
+
+  public void testPutNonChars() {
+    Hasher hasher = HASH_FN.newHasher();
+    // Expected data is 0x0100010100000000
+    hasher
+        .putBoolean(true)
+        .putBoolean(true)
+        .putBoolean(false)
+        .putBoolean(true)
+        .putBoolean(false)
+        .putBoolean(false)
+        .putBoolean(false)
+        .putBoolean(false);
+    final long hashCode = hasher.hash().asLong();
+
+    hasher = HASH_FN.newHasher();
+    hasher
+        .putByte((byte) 0x01)
+        .putByte((byte) 0x01)
+        .putByte((byte) 0x00)
+        .putByte((byte) 0x01)
+        .putByte((byte) 0x00)
+        .putByte((byte) 0x00)
+        .putByte((byte) 0x00)
+        .putByte((byte) 0x00);
+    assertEquals(hashCode, hasher.hash().asLong());
+
+    hasher = HASH_FN.newHasher();
+    hasher
+        .putChar((char) 0x0101)
+        .putChar((char) 0x0100)
+        .putChar((char) 0x0000)
+        .putChar((char) 0x0000);
+    assertEquals(hashCode, hasher.hash().asLong());
+
+    hasher = HASH_FN.newHasher();
+    hasher.putBytes(new byte[] {0x01, 0x01, 0x00, 0x01, 0x00, 0x00, 0x00, 0x00});
+    assertEquals(hashCode, hasher.hash().asLong());
+
+    hasher = HASH_FN.newHasher();
+    hasher.putLong(0x0000000001000101L);
+    assertEquals(hashCode, hasher.hash().asLong());
+
+    hasher = HASH_FN.newHasher();
+    hasher
+        .putShort((short) 0x0101)
+        .putShort((short) 0x0100)
+        .putShort((short) 0x0000)
+        .putShort((short) 0x0000);
+    assertEquals(hashCode, hasher.hash().asLong());
+  }
+
+  public void testHashFloatIsStable() {
+    // This is about the best we can do for floating-point
+    Hasher hasher = HASH_FN.newHasher();
+    hasher.putFloat(0x01000101f).putFloat(0f);
+    assertEquals(0x96a4f8cc6ecbf16L, hasher.hash().asLong());
+
+    hasher = HASH_FN.newHasher();
+    hasher.putDouble(0x0000000001000101d);
+    assertEquals(0xcf54171253fdc198L, hasher.hash().asLong());
+  }
+
+  /** Convenience method to compute a fingerprint on a full bytes array. */
+  private static long fingerprint(byte[] bytes) {
+    return fingerprint(bytes, bytes.length);
+  }
+
+  /** Convenience method to compute a fingerprint on a subset of a byte array. */
+  private static long fingerprint(byte[] bytes, int length) {
+    return HASH_FN.hashBytes(bytes, 0, length).asLong();
+  }
+
+  /**
+   * Tests that the Java port of Fingerprint2011 provides the same results on buffers up to 800
+   * bytes long as the original implementation in C++. See http://cl/106539598
+   */
+  public void testMultipleLengths() {
+    int iterations = 800;
+    byte[] buf = new byte[iterations * 4];
+    int bufLen = 0;
+    long h = 0;
+    for (int i = 0; i < iterations; ++i) {
+      h ^= fingerprint(buf, i);
+      h = remix(h);
+      buf[bufLen++] = getChar(h);
+
+      h ^= fingerprint(buf, i * i % bufLen);
+      h = remix(h);
+      buf[bufLen++] = getChar(h);
+
+      h ^= fingerprint(buf, i * i * i % bufLen);
+      h = remix(h);
+      buf[bufLen++] = getChar(h);
+
+      h ^= fingerprint(buf, bufLen);
+      h = remix(h);
+      buf[bufLen++] = getChar(h);
+
+      int x0 = buf[bufLen - 1] & 0xff;
+      int x1 = buf[bufLen - 2] & 0xff;
+      int x2 = buf[bufLen - 3] & 0xff;
+      int x3 = buf[bufLen / 2] & 0xff;
+      buf[((x0 << 16) + (x1 << 8) + x2) % bufLen] ^= x3;
+      buf[((x1 << 16) + (x2 << 8) + x3) % bufLen] ^= i % 256;
+    }
+    assertEquals(0xeaa3b1c985261632L, h);
+  }
+
+  private static long remix(long h) {
+    h ^= h >>> 41;
+    h *= 949921979;
+    return h;
+  }
+
+  private static byte getChar(long h) {
+    return (byte) ('a' + ((h & 0xfffff) % 26));
+  }
+}
diff --git a/guava-tests/test/com/google/common/hash/HashFunctionEnum.java b/guava-tests/test/com/google/common/hash/HashFunctionEnum.java
index 3a98fede9540..34717477e645 100644
--- a/guava-tests/test/com/google/common/hash/HashFunctionEnum.java
+++ b/guava-tests/test/com/google/common/hash/HashFunctionEnum.java
@@ -32,6 +32,7 @@ enum HashFunctionEnum {
   MD5(Hashing.md5()),
   MURMUR3_128(Hashing.murmur3_128()),
   MURMUR3_32(Hashing.murmur3_32()),
+  MURMUR3_32_FIXED(Hashing.murmur3_32_fixed()),
   SHA1(Hashing.sha1()),
   SHA256(Hashing.sha256()),
   SHA384(Hashing.sha384()),
diff --git a/guava-tests/test/com/google/common/hash/HashTestUtils.java b/guava-tests/test/com/google/common/hash/HashTestUtils.java
index 8dfbdb0cdf03..9e9944b5abfb 100644
--- a/guava-tests/test/com/google/common/hash/HashTestUtils.java
+++ b/guava-tests/test/com/google/common/hash/HashTestUtils.java
@@ -195,8 +195,8 @@ void performAction(Random random, Iterable<? extends PrimitiveSink> sinks) {
         int limit = pos + random.nextInt(value.length - pos + 1);
         for (PrimitiveSink sink : sinks) {
           ByteBuffer buffer = ByteBuffer.wrap(value);
-          buffer.position(pos);
-          buffer.limit(limit);
+          Java8Compatibility.position(buffer, pos);
+          Java8Compatibility.limit(buffer, limit);
           sink.putBytes(buffer);
           assertEquals(limit, buffer.limit());
           assertEquals(limit, buffer.position());
diff --git a/guava-tests/test/com/google/common/hash/HashingTest.java b/guava-tests/test/com/google/common/hash/HashingTest.java
index dc50299ea00f..aff5c254fac2 100644
--- a/guava-tests/test/com/google/common/hash/HashingTest.java
+++ b/guava-tests/test/com/google/common/hash/HashingTest.java
@@ -125,6 +125,15 @@ public void testSipHash24() {
         Hashing.sipHash24().toString());
   }
 
+  public void testFingerprint2011() {
+    HashTestUtils.check2BitAvalanche(Hashing.fingerprint2011(), 100, 0.4);
+    HashTestUtils.checkAvalanche(Hashing.fingerprint2011(), 100, 0.4);
+    HashTestUtils.checkNo2BitCharacteristics(Hashing.fingerprint2011());
+    HashTestUtils.checkNoFunnels(Hashing.fingerprint2011());
+    HashTestUtils.assertInvariants(Hashing.fingerprint2011());
+    assertEquals("Hashing.fingerprint2011()", Hashing.fingerprint2011().toString());
+  }
+
   @AndroidIncompatible // slow TODO(cpovirk): Maybe just reduce iterations under Android.
   public void testGoodFastHash() {
     for (int i = 1; i < 200; i += 17) {
@@ -146,7 +155,7 @@ public void testGoodFastHash32() {
   // goodFastHash(128) uses Murmur3_128. Use the same epsilon bounds.
   public void testGoodFastHash128() {
     HashTestUtils.check2BitAvalanche(Hashing.goodFastHash(128), 250, 0.20);
-    HashTestUtils.checkAvalanche(Hashing.goodFastHash(128), 250, 0.17);
+    HashTestUtils.checkAvalanche(Hashing.goodFastHash(128), 500, 0.17);
     HashTestUtils.checkNo2BitCharacteristics(Hashing.goodFastHash(128));
     HashTestUtils.checkNoFunnels(Hashing.goodFastHash(128));
     HashTestUtils.assertInvariants(Hashing.goodFastHash(128));
@@ -155,7 +164,7 @@ public void testGoodFastHash128() {
   // goodFastHash(256) uses Murmur3_128. Use the same epsilon bounds.
   public void testGoodFastHash256() {
     HashTestUtils.check2BitAvalanche(Hashing.goodFastHash(256), 250, 0.20);
-    HashTestUtils.checkAvalanche(Hashing.goodFastHash(256), 250, 0.17);
+    HashTestUtils.checkAvalanche(Hashing.goodFastHash(256), 500, 0.17);
     HashTestUtils.checkNo2BitCharacteristics(Hashing.goodFastHash(256));
     HashTestUtils.checkNoFunnels(Hashing.goodFastHash(256));
     HashTestUtils.assertInvariants(Hashing.goodFastHash(256));
@@ -432,6 +441,9 @@ public void testHashIntVsForLoop() {
           .put(Hashing.murmur3_32(), EMPTY_STRING, "00000000")
           .put(Hashing.murmur3_32(), TQBFJOTLD, "23f74f2e")
           .put(Hashing.murmur3_32(), TQBFJOTLDP, "fc8bc4d5")
+          .put(Hashing.murmur3_32_fixed(), EMPTY_STRING, "00000000")
+          .put(Hashing.murmur3_32_fixed(), TQBFJOTLD, "23f74f2e")
+          .put(Hashing.murmur3_32_fixed(), TQBFJOTLDP, "fc8bc4d5")
           .put(Hashing.sha1(), EMPTY_STRING, "da39a3ee5e6b4b0d3255bfef95601890afd80709")
           .put(Hashing.sha1(), TQBFJOTLD, "2fd4e1c67a2d28fced849ee1bb76e7391b93eb12")
           .put(Hashing.sha1(), TQBFJOTLDP, "408d94384216f890ff7a0c3528e8bed1e0b01621")
@@ -489,6 +501,9 @@ public void testHashIntVsForLoop() {
           .put(Hashing.farmHashFingerprint64(), EMPTY_STRING, "4f40902f3b6ae19a")
           .put(Hashing.farmHashFingerprint64(), TQBFJOTLD, "34511b3bf383beab")
           .put(Hashing.farmHashFingerprint64(), TQBFJOTLDP, "737d7e5f8660653e")
+          .put(Hashing.fingerprint2011(), EMPTY_STRING, "e365a64a907cad23")
+          .put(Hashing.fingerprint2011(), TQBFJOTLD, "c9688c84e813b089")
+          .put(Hashing.fingerprint2011(), TQBFJOTLDP, "a714d70f1d569cd0")
           .build();
 
   public void testAllHashFunctionsHaveKnownHashes() throws Exception {
diff --git a/guava-tests/test/com/google/common/hash/Murmur3Hash32Test.java b/guava-tests/test/com/google/common/hash/Murmur3Hash32Test.java
index de86e4bbd86b..181b2a7bb071 100644
--- a/guava-tests/test/com/google/common/hash/Murmur3Hash32Test.java
+++ b/guava-tests/test/com/google/common/hash/Murmur3Hash32Test.java
@@ -17,9 +17,11 @@
 package com.google.common.hash;
 
 import static com.google.common.hash.Hashing.murmur3_32;
+import static com.google.common.hash.Hashing.murmur3_32_fixed;
 
 import com.google.common.base.Charsets;
 import com.google.common.hash.HashTestUtils.HashFn;
+import java.nio.charset.Charset;
 import java.util.Random;
 import junit.framework.TestCase;
 
@@ -51,16 +53,53 @@ public void testKnownStringInputs() {
         -528633700, murmur3_32().hashUnencodedChars("The quick brown fox jumps over the lazy dog"));
   }
 
-  public void testKnownUtf8StringInputs() {
-    assertHash(0, murmur3_32().hashString("", Charsets.UTF_8));
-    assertHash(0xcfbda5d1, murmur3_32().hashString("k", Charsets.UTF_8));
-    assertHash(0xa167dbf3, murmur3_32().hashString("hell", Charsets.UTF_8));
-    assertHash(0x248bfa47, murmur3_32().hashString("hello", Charsets.UTF_8));
-    assertHash(0x3d41b97c, murmur3_32().hashString("http://www.google.com/", Charsets.UTF_8));
-    assertHash(
-        0x2e4ff723,
-        murmur3_32().hashString("The quick brown fox jumps over the lazy dog", Charsets.UTF_8));
-    assertHash(0xfc5ba834, murmur3_32().hashString("毎月１日,毎週月曜日", Charsets.UTF_8));
+  @SuppressWarnings("deprecation")
+  public void testKnownEncodedStringInputs() {
+    assertStringHash(0, "", Charsets.UTF_8);
+    assertStringHash(0xcfbda5d1, "k", Charsets.UTF_8);
+    assertStringHash(0xa167dbf3, "hell", Charsets.UTF_8);
+    assertStringHash(0x248bfa47, "hello", Charsets.UTF_8);
+    assertStringHash(0x3d41b97c, "http://www.google.com/", Charsets.UTF_8);
+    assertStringHash(0x2e4ff723, "The quick brown fox jumps over the lazy dog", Charsets.UTF_8);
+    assertStringHash(0xb5a4be05, "ABCDefGHI\u0799", Charsets.UTF_8);
+    assertStringHash(0xfc5ba834, "毎月１日,毎週月曜日", Charsets.UTF_8);
+    assertStringHash(0x8a5c3699, "surrogate pair: \uD83D\uDCB0", Charsets.UTF_8);
+
+    assertStringHash(0, "", Charsets.UTF_16LE);
+    assertStringHash(0x288418e4, "k", Charsets.UTF_16LE);
+    assertStringHash(0x5a0cb7c3, "hell", Charsets.UTF_16LE);
+    assertStringHash(0xd7c31989, "hello", Charsets.UTF_16LE);
+    assertStringHash(0x73564d8c, "http://www.google.com/", Charsets.UTF_16LE);
+    assertStringHash(0xe07db09c, "The quick brown fox jumps over the lazy dog", Charsets.UTF_16LE);
+    assertStringHash(0xfefa3e76, "ABCDefGHI\u0799", Charsets.UTF_16LE);
+    assertStringHash(0x6a7be132, "毎月１日,毎週月曜日", Charsets.UTF_16LE);
+    assertStringHash(0x5a2d41c7, "surrogate pair: \uD83D\uDCB0", Charsets.UTF_16LE);
+  }
+
+  @SuppressWarnings("deprecation")
+  private void assertStringHash(int expected, String string, Charset charset) {
+    if (allBmp(string)) {
+      assertHash(expected, murmur3_32().hashString(string, charset));
+    }
+    assertHash(expected, murmur3_32_fixed().hashString(string, charset));
+    assertHash(expected, murmur3_32().newHasher().putString(string, charset).hash());
+    assertHash(expected, murmur3_32_fixed().newHasher().putString(string, charset).hash());
+    assertHash(expected, murmur3_32().hashBytes(string.getBytes(charset)));
+    assertHash(expected, murmur3_32_fixed().hashBytes(string.getBytes(charset)));
+    assertHash(expected, murmur3_32().newHasher().putBytes(string.getBytes(charset)).hash());
+    assertHash(expected, murmur3_32_fixed().newHasher().putBytes(string.getBytes(charset)).hash());
+  }
+
+  private boolean allBmp(String string) {
+    // Ordinarily we'd use something like i += Character.charCount(string.codePointAt(i)) here. But
+    // we can get away with i++ because the whole point of this method is to return false if we find
+    // a code point that doesn't fit in a char.
+    for (int i = 0; i < string.length(); i++) {
+      if (string.codePointAt(i) > 0xffff) {
+        return false;
+      }
+    }
+    return true;
   }
 
   @SuppressWarnings("deprecation")
@@ -71,7 +110,7 @@ public void testSimpleStringUtf8() {
   }
 
   @SuppressWarnings("deprecation")
-  public void testStringInputsUtf8() {
+  public void testEncodedStringInputs() {
     Random rng = new Random(0);
     for (int z = 0; z < 100; z++) {
       String str;
@@ -88,9 +127,16 @@ public void testStringInputsUtf8() {
         builder.appendCodePoint(codePoints[i]);
       }
       str = builder.toString();
+      HashCode hashUtf8 = murmur3_32().hashBytes(str.getBytes(Charsets.UTF_8));
+      assertEquals(
+          hashUtf8, murmur3_32().newHasher().putBytes(str.getBytes(Charsets.UTF_8)).hash());
+      assertEquals(hashUtf8, murmur3_32().hashString(str, Charsets.UTF_8));
+      assertEquals(hashUtf8, murmur3_32().newHasher().putString(str, Charsets.UTF_8).hash());
+      HashCode hashUtf16 = murmur3_32().hashBytes(str.getBytes(Charsets.UTF_16));
       assertEquals(
-          murmur3_32().hashBytes(str.getBytes(Charsets.UTF_8)),
-          murmur3_32().hashString(str, Charsets.UTF_8));
+          hashUtf16, murmur3_32().newHasher().putBytes(str.getBytes(Charsets.UTF_16)).hash());
+      assertEquals(hashUtf16, murmur3_32().hashString(str, Charsets.UTF_16));
+      assertEquals(hashUtf16, murmur3_32().newHasher().putString(str, Charsets.UTF_16).hash());
     }
   }
 
@@ -138,8 +184,12 @@ public void testInvalidUnicodeHashString() {
     assertEquals(
         murmur3_32().hashBytes(str.getBytes(Charsets.UTF_8)),
         murmur3_32().hashString(str, Charsets.UTF_8));
+    assertEquals(
+        murmur3_32_fixed().hashBytes(str.getBytes(Charsets.UTF_8)),
+        murmur3_32().hashString(str, Charsets.UTF_8));
   }
 
+  @SuppressWarnings("deprecation")
   public void testInvalidUnicodeHasherPutString() {
     String str =
         new String(
@@ -147,5 +197,8 @@ public void testInvalidUnicodeHasherPutString() {
     assertEquals(
         murmur3_32().hashBytes(str.getBytes(Charsets.UTF_8)),
         murmur3_32().newHasher().putString(str, Charsets.UTF_8).hash());
+    assertEquals(
+        murmur3_32_fixed().hashBytes(str.getBytes(Charsets.UTF_8)),
+        murmur3_32_fixed().newHasher().putString(str, Charsets.UTF_8).hash());
   }
 }
diff --git a/guava-tests/test/com/google/common/io/ByteSourceTest.java b/guava-tests/test/com/google/common/io/ByteSourceTest.java
index f0ba829b22eb..3cf6cca44259 100644
--- a/guava-tests/test/com/google/common/io/ByteSourceTest.java
+++ b/guava-tests/test/com/google/common/io/ByteSourceTest.java
@@ -30,6 +30,7 @@
 import com.google.common.collect.ImmutableSet;
 import com.google.common.collect.Iterables;
 import com.google.common.hash.Hashing;
+import com.google.common.io.Closer.LoggingSuppressor;
 import com.google.common.primitives.UnsignedBytes;
 import com.google.common.testing.TestLogHandler;
 import java.io.ByteArrayOutputStream;
@@ -395,7 +396,7 @@ public void testConcat_infiniteIterable() throws IOException {
       ImmutableSet.of(BROKEN_CLOSE_SINK, BROKEN_OPEN_SINK, BROKEN_WRITE_SINK);
 
   public void testCopyExceptions() {
-    if (!Closer.SuppressingSuppressor.isAvailable()) {
+    if (Closer.create().suppressor instanceof LoggingSuppressor) {
       // test that exceptions are logged
 
       TestLogHandler logHandler = new TestLogHandler();
diff --git a/guava-tests/test/com/google/common/io/ByteSourceTester.java b/guava-tests/test/com/google/common/io/ByteSourceTester.java
index 490f1e6c5df7..75854125606a 100644
--- a/guava-tests/test/com/google/common/io/ByteSourceTester.java
+++ b/guava-tests/test/com/google/common/io/ByteSourceTester.java
@@ -38,7 +38,7 @@
 /**
  * A generator of {@code TestSuite} instances for testing {@code ByteSource} implementations.
  * Generates tests of a all methods on a {@code ByteSource} given various inputs the source is
- * expected to contain as well as as sub-suites for testing the {@code CharSource} view and {@code
+ * expected to contain as well as sub-suites for testing the {@code CharSource} view and {@code
  * slice()} views in the same way.
  *
  * @author Colin Decker
diff --git a/guava-tests/test/com/google/common/io/ByteStreamsTest.java b/guava-tests/test/com/google/common/io/ByteStreamsTest.java
index 3ae2c2559827..dddae1ffc21a 100644
--- a/guava-tests/test/com/google/common/io/ByteStreamsTest.java
+++ b/guava-tests/test/com/google/common/io/ByteStreamsTest.java
@@ -562,12 +562,49 @@ public void testNullOutputStream() throws Exception {
     // write to the output stream
     nos.write('n');
     String test = "Test string for NullOutputStream";
-    nos.write(test.getBytes());
-    nos.write(test.getBytes(), 2, 10);
+    byte[] bytes = test.getBytes(Charsets.US_ASCII);
+    nos.write(bytes);
+    nos.write(bytes, 2, 10);
+    nos.write(bytes, bytes.length - 5, 5);
     // nothing really to assert?
     assertSame(ByteStreams.nullOutputStream(), ByteStreams.nullOutputStream());
   }
 
+  public void testNullOutputStream_exceptions() throws Exception {
+    OutputStream nos = ByteStreams.nullOutputStream();
+    try {
+      nos.write(null);
+      fail();
+    } catch (NullPointerException expected) {
+    }
+    try {
+      nos.write(null, 0, 1);
+      fail();
+    } catch (NullPointerException expected) {
+    }
+    byte[] tenBytes = new byte[10];
+    try {
+      nos.write(tenBytes, -1, 1);
+      fail("Expected exception from negative offset");
+    } catch (IndexOutOfBoundsException expected) {
+    }
+    try {
+      nos.write(tenBytes, 1, -1);
+      fail("Expected exception from negative length");
+    } catch (IndexOutOfBoundsException expected) {
+    }
+    try {
+      nos.write(tenBytes, 9, 2);
+      fail("Expected exception from offset+length > array size");
+    } catch (IndexOutOfBoundsException expected) {
+    }
+    try {
+      nos.write(tenBytes, 9, 100);
+      fail("Expected exception from offset+length > array size");
+    } catch (IndexOutOfBoundsException expected) {
+    }
+  }
+
   public void testLimit() throws Exception {
     byte[] big = newPreFilledByteArray(5);
     InputStream bin = new ByteArrayInputStream(big);
diff --git a/guava-tests/test/com/google/common/io/CharSequenceReaderTest.java b/guava-tests/test/com/google/common/io/CharSequenceReaderTest.java
index 12bc17e588e3..dbe94fcf71fa 100644
--- a/guava-tests/test/com/google/common/io/CharSequenceReaderTest.java
+++ b/guava-tests/test/com/google/common/io/CharSequenceReaderTest.java
@@ -211,7 +211,7 @@ private static void assertReadsCorrectly(CharSequence charSequence) throws IOExc
     reader = new CharSequenceReader(charSequence);
     CharBuffer buf2 = CharBuffer.allocate(expected.length());
     assertEquals(expected.length() == 0 ? -1 : expected.length(), reader.read(buf2));
-    buf2.flip();
+    Java8Compatibility.flip(buf2);
     assertEquals(expected, buf2.toString());
     assertFullyRead(reader);
 
@@ -220,9 +220,9 @@ private static void assertReadsCorrectly(CharSequence charSequence) throws IOExc
     buf2 = CharBuffer.allocate(5);
     builder = new StringBuilder();
     while (reader.read(buf2) != -1) {
-      buf2.flip();
+      Java8Compatibility.flip(buf2);
       builder.append(buf2);
-      buf2.clear();
+      Java8Compatibility.clear(buf2);
     }
     assertEquals(expected, builder.toString());
     assertFullyRead(reader);
diff --git a/guava-tests/test/com/google/common/io/CharSourceTest.java b/guava-tests/test/com/google/common/io/CharSourceTest.java
index c4fbe46802cb..787d744b7e48 100644
--- a/guava-tests/test/com/google/common/io/CharSourceTest.java
+++ b/guava-tests/test/com/google/common/io/CharSourceTest.java
@@ -26,6 +26,7 @@
 import com.google.common.collect.ImmutableSet;
 import com.google.common.collect.Iterables;
 import com.google.common.collect.Lists;
+import com.google.common.io.Closer.LoggingSuppressor;
 import com.google.common.testing.TestLogHandler;
 import java.io.BufferedReader;
 import java.io.IOException;
@@ -288,7 +289,7 @@ public void testConcat_infiniteIterable() throws IOException {
       ImmutableSet.of(BROKEN_CLOSE_SINK, BROKEN_OPEN_SINK, BROKEN_WRITE_SINK);
 
   public void testCopyExceptions() {
-    if (!Closer.SuppressingSuppressor.isAvailable()) {
+    if (Closer.create().suppressor instanceof LoggingSuppressor) {
       // test that exceptions are logged
 
       TestLogHandler logHandler = new TestLogHandler();
diff --git a/guava-tests/test/com/google/common/io/CloserTest.java b/guava-tests/test/com/google/common/io/CloserTest.java
index 3d16a09906b1..3876174eacb7 100644
--- a/guava-tests/test/com/google/common/io/CloserTest.java
+++ b/guava-tests/test/com/google/common/io/CloserTest.java
@@ -24,6 +24,7 @@
 import com.google.common.collect.ImmutableList;
 import com.google.common.collect.ImmutableSet;
 import com.google.common.collect.Lists;
+import com.google.common.io.Closer.LoggingSuppressor;
 import com.google.common.testing.TestLogHandler;
 import java.io.Closeable;
 import java.io.IOException;
@@ -311,13 +312,12 @@ record = logHandler.getStoredLogRecords().get(1);
   }
 
   public static void testSuppressingSuppressorIfPossible() throws IOException {
+    Closer closer = Closer.create();
     // can't test the JDK7 suppressor when not running on JDK7
-    if (!Closer.SuppressingSuppressor.isAvailable()) {
+    if (closer.suppressor instanceof LoggingSuppressor) {
       return;
     }
 
-    Closer closer = new Closer(new Closer.SuppressingSuppressor());
-
     IOException thrownException = new IOException();
     IOException c1Exception = new IOException();
     RuntimeException c2Exception = new RuntimeException();
diff --git a/guava-tests/test/com/google/common/io/LittleEndianDataInputStreamTest.java b/guava-tests/test/com/google/common/io/LittleEndianDataInputStreamTest.java
index f8e40df25a98..160df410bed6 100644
--- a/guava-tests/test/com/google/common/io/LittleEndianDataInputStreamTest.java
+++ b/guava-tests/test/com/google/common/io/LittleEndianDataInputStreamTest.java
@@ -92,6 +92,7 @@ public void testReadUnsignedShort_eof() throws IOException {
     }
   }
 
+  @SuppressWarnings("DoNotCall")
   public void testReadLine() throws IOException {
     DataInput in = new LittleEndianDataInputStream(new ByteArrayInputStream(data));
     try {
diff --git a/guava-tests/test/com/google/common/io/MoreFilesTest.java b/guava-tests/test/com/google/common/io/MoreFilesTest.java
index 91df973530c3..005cf531da54 100644
--- a/guava-tests/test/com/google/common/io/MoreFilesTest.java
+++ b/guava-tests/test/com/google/common/io/MoreFilesTest.java
@@ -34,6 +34,7 @@
 import java.nio.file.FileSystems;
 import java.nio.file.FileVisitResult;
 import java.nio.file.Files;
+import java.nio.file.NoSuchFileException;
 import java.nio.file.Path;
 import java.nio.file.SimpleFileVisitor;
 import java.nio.file.attribute.BasicFileAttributes;
@@ -556,6 +557,17 @@ public void testDeleteRecursively_symlinkToDir_sdsNotSupported_allowInsecure()
     }
   }
 
+  public void testDeleteRecursively_nonexistingFile_throwsNoSuchFileException() throws IOException {
+    try (FileSystem fs = newTestFileSystem()) {
+      try {
+        MoreFiles.deleteRecursively(fs.getPath("/work/nothere"), ALLOW_INSECURE);
+        fail();
+      } catch (NoSuchFileException expected) {
+        assertThat(expected.getFile()).isEqualTo("/work/nothere");
+      }
+    }
+  }
+
   public void testDeleteDirectoryContents_symlinkToDir_sdsNotSupported_allowInsecure()
       throws IOException {
     try (FileSystem fs = newTestFileSystem()) {
diff --git a/guava-tests/test/com/google/common/io/PatternFilenameFilterTest.java b/guava-tests/test/com/google/common/io/PatternFilenameFilterTest.java
index 77ace52f2506..94ab1f01683a 100644
--- a/guava-tests/test/com/google/common/io/PatternFilenameFilterTest.java
+++ b/guava-tests/test/com/google/common/io/PatternFilenameFilterTest.java
@@ -16,6 +16,8 @@
 
 package com.google.common.io;
 
+import com.google.common.testing.NullPointerTester;
+import com.google.common.testing.NullPointerTester.Visibility;
 import java.io.File;
 import java.io.FilenameFilter;
 import java.util.regex.PatternSyntaxException;
@@ -46,4 +48,15 @@ public void testAccept() {
     // Show that dir is ignored
     assertTrue(filter.accept(null, "a"));
   }
+
+  public void testNulls() throws Exception {
+    NullPointerTester tester = new NullPointerTester();
+
+    tester.testConstructors(PatternFilenameFilter.class, Visibility.PACKAGE);
+    tester.testStaticMethods(PatternFilenameFilter.class, Visibility.PACKAGE); // currently none
+
+    // The reason that we skip this method is discussed in a comment on the method.
+    tester.ignore(PatternFilenameFilter.class.getMethod("accept", File.class, String.class));
+    tester.testInstanceMethods(new PatternFilenameFilter(".*"), Visibility.PACKAGE);
+  }
 }
diff --git a/guava-tests/test/com/google/common/io/SourceSinkFactories.java b/guava-tests/test/com/google/common/io/SourceSinkFactories.java
index 9b761d37450e..d24622d0aeda 100644
--- a/guava-tests/test/com/google/common/io/SourceSinkFactories.java
+++ b/guava-tests/test/com/google/common/io/SourceSinkFactories.java
@@ -442,9 +442,9 @@ public String getSinkContents() throws IOException {
       StringBuilder builder = new StringBuilder();
       CharBuffer buffer = CharBuffer.allocate(100);
       while (reader.read(buffer) != -1) {
-        buffer.flip();
+        Java8Compatibility.flip(buffer);
         builder.append(buffer);
-        buffer.clear();
+        Java8Compatibility.clear(buffer);
       }
       return builder.toString();
     }
diff --git a/guava-tests/test/com/google/common/io/SourceSinkTester.java b/guava-tests/test/com/google/common/io/SourceSinkTester.java
index 9b07355a6939..55a302f850c5 100644
--- a/guava-tests/test/com/google/common/io/SourceSinkTester.java
+++ b/guava-tests/test/com/google/common/io/SourceSinkTester.java
@@ -69,7 +69,7 @@ public class SourceSinkTester<S, T, F extends SourceSinkFactory<S, T>> extends T
           .put("\\n at EOF", "hello\nworld\n")
           .put("\\r at EOF", "hello\nworld\r")
           .put("lorem ipsum", LOREM_IPSUM)
-          .build();
+          .buildOrThrow();
 
   protected final F factory;
   protected final T data;
diff --git a/guava-tests/test/com/google/common/math/IntMathTest.java b/guava-tests/test/com/google/common/math/IntMathTest.java
index 12b23e214728..4db13adbddd5 100644
--- a/guava-tests/test/com/google/common/math/IntMathTest.java
+++ b/guava-tests/test/com/google/common/math/IntMathTest.java
@@ -137,10 +137,11 @@ public void testMaxLog10ForLeadingZeros() {
   @GwtIncompatible // BigIntegerMath // TODO(cpovirk): GWT-enable BigIntegerMath
   public void testConstantsHalfPowersOf10() {
     for (int i = 0; i < IntMath.halfPowersOf10.length; i++) {
-      assert IntMath.halfPowersOf10[i]
-          == Math.min(
+      assertEquals(
+          IntMath.halfPowersOf10[i],
+          Math.min(
               Integer.MAX_VALUE,
-              BigIntegerMath.sqrt(BigInteger.TEN.pow(2 * i + 1), FLOOR).longValue());
+              BigIntegerMath.sqrt(BigInteger.TEN.pow(2 * i + 1), FLOOR).longValue()));
     }
   }
 
diff --git a/guava-tests/test/com/google/common/math/MathPreconditionsTest.java b/guava-tests/test/com/google/common/math/MathPreconditionsTest.java
index 69719e013572..5dbe017c142d 100644
--- a/guava-tests/test/com/google/common/math/MathPreconditionsTest.java
+++ b/guava-tests/test/com/google/common/math/MathPreconditionsTest.java
@@ -289,4 +289,15 @@ public void testCheckNoOverflow_failure() {
       assertThat(expected).hasMessageThat().contains("testCheckNoOverflow_failure(0, 0)");
     }
   }
+
+  public void testNulls() {
+    /*
+     * Don't bother testing. All non-primitive parameters are used only to construct error messages.
+     * We never want to pass null for them, so we haven't annotated them to say that null is
+     * allowed. But at the same time, it seems wasteful to bother inserting the checkNotNull calls
+     * that NullPointerTester wants.
+     *
+     * (This empty method disables the automatic null testing provided by PackageSanityTests.)
+     */
+  }
 }
diff --git a/guava-tests/test/com/google/common/math/QuantilesAlgorithm.java b/guava-tests/test/com/google/common/math/QuantilesAlgorithm.java
index 54d310f0d2d6..ddb2064e20b6 100644
--- a/guava-tests/test/com/google/common/math/QuantilesAlgorithm.java
+++ b/guava-tests/test/com/google/common/math/QuantilesAlgorithm.java
@@ -53,7 +53,7 @@ Map<Integer, Double> multipleQuantiles(
       for (int index : indexes) {
         builder.put(index, singleQuantileFromSorted(index, scale, dataset));
       }
-      return builder.build();
+      return builder.buildOrThrow();
     }
 
     private double singleQuantileFromSorted(int index, int scale, double[] dataset) {
@@ -97,7 +97,7 @@ Map<Integer, Double> multipleQuantiles(
       for (int index : indexes) {
         builder.put(index, singleQuantile(index, scale, dataset));
       }
-      return builder.build();
+      return builder.buildOrThrow();
     }
   },
 
diff --git a/guava-tests/test/com/google/common/math/QuantilesTest.java b/guava-tests/test/com/google/common/math/QuantilesTest.java
index a9b7872994cb..e5d113dfca6a 100644
--- a/guava-tests/test/com/google/common/math/QuantilesTest.java
+++ b/guava-tests/test/com/google/common/math/QuantilesTest.java
@@ -557,7 +557,7 @@ public void testPercentiles_indexes_varargsPairs_compute_doubleCollection() {
         }
         assertThat(percentiles().indexes(index1, index2).compute(PSEUDORANDOM_DATASET))
             .comparingValuesUsing(QUANTILE_CORRESPONDENCE)
-            .containsExactlyEntriesIn(expectedBuilder.build());
+            .containsExactlyEntriesIn(expectedBuilder.buildOrThrow());
       }
     }
   }
@@ -573,7 +573,7 @@ public void testPercentiles_indexes_varargsAll_compute_doubleCollection() {
     Collections.shuffle(indexes, random);
     assertThat(percentiles().indexes(Ints.toArray(indexes)).compute(PSEUDORANDOM_DATASET))
         .comparingValuesUsing(QUANTILE_CORRESPONDENCE)
-        .containsExactlyEntriesIn(expectedBuilder.build());
+        .containsExactlyEntriesIn(expectedBuilder.buildOrThrow());
   }
 
   @AndroidIncompatible // slow
@@ -589,7 +589,7 @@ public void testPercentiles_indexes_varargsAll_computeInPlace() {
     Collections.shuffle(indexes, random);
     assertThat(percentiles().indexes(Ints.toArray(indexes)).computeInPlace(dataset))
         .comparingValuesUsing(QUANTILE_CORRESPONDENCE)
-        .containsExactlyEntriesIn(expectedBuilder.build());
+        .containsExactlyEntriesIn(expectedBuilder.buildOrThrow());
     assertThat(dataset).usingExactEquality().containsExactlyElementsIn(PSEUDORANDOM_DATASET);
   }
 
diff --git a/guava-tests/test/com/google/common/net/HostAndPortTest.java b/guava-tests/test/com/google/common/net/HostAndPortTest.java
index 5e7eb2f73d71..65e80962bafa 100644
--- a/guava-tests/test/com/google/common/net/HostAndPortTest.java
+++ b/guava-tests/test/com/google/common/net/HostAndPortTest.java
@@ -59,6 +59,13 @@ public void testFromStringUnusedDefaultPort() {
     checkFromStringCase("[2001::2]:85", 77, "2001::2", 85, true);
   }
 
+  public void testFromStringNonAsciiDigits() {
+    // Same as testFromStringUnusedDefaultPort but with Gujarati digits for port numbers.
+    checkFromStringCase("gmail.com:૮1", 77, null, -1, false);
+    checkFromStringCase("192.0.2.2:૮૩", 77, null, -1, false);
+    checkFromStringCase("[2001::2]:૮૫", 77, null, -1, false);
+  }
+
   public void testFromStringBadPort() {
     // Out-of-range ports.
     checkFromStringCase("google.com:65536", 1, null, 99, false);
diff --git a/guava-tests/test/com/google/common/net/HostSpecifierTest.java b/guava-tests/test/com/google/common/net/HostSpecifierTest.java
index fadeff7aadf4..8112879a86d9 100644
--- a/guava-tests/test/com/google/common/net/HostSpecifierTest.java
+++ b/guava-tests/test/com/google/common/net/HostSpecifierTest.java
@@ -92,8 +92,9 @@ public void testNulls() {
   }
 
   private void assertGood(String spec) throws ParseException {
-    HostSpecifier.fromValid(spec); // Throws exception if not working correctly
-    HostSpecifier.from(spec);
+    // Throws exception if not working correctly
+    HostSpecifier unused = HostSpecifier.fromValid(spec);
+    unused = HostSpecifier.from(spec);
     assertTrue(HostSpecifier.isValid(spec));
   }
 
diff --git a/guava-tests/test/com/google/common/net/HttpHeadersTest.java b/guava-tests/test/com/google/common/net/HttpHeadersTest.java
index 9927e6b94e00..5361b3fcea61 100644
--- a/guava-tests/test/com/google/common/net/HttpHeadersTest.java
+++ b/guava-tests/test/com/google/common/net/HttpHeadersTest.java
@@ -50,8 +50,8 @@ public void testConstantNameMatchesString() throws Exception {
             .build();
     ImmutableSet<String> uppercaseAcronyms =
         ImmutableSet.of(
-            "CH", "ID", "DNT", "DNS", "HTTP2", "IP", "MD5", "P3P", "TE", "UA", "UID", "URL", "WWW",
-            "XSS");
+            "CH", "ID", "DNT", "DNS", "ECT", "HTTP2", "IP", "MD5", "P3P", "RTT", "TE", "UA", "UID",
+            "URL", "WWW", "XSS");
     assertConstantNameMatchesString(HttpHeaders.class, specialCases, uppercaseAcronyms);
   }
 
diff --git a/guava-tests/test/com/google/common/net/InetAddressesTest.java b/guava-tests/test/com/google/common/net/InetAddressesTest.java
index ed3aa272d3a6..be77e7b17f08 100644
--- a/guava-tests/test/com/google/common/net/InetAddressesTest.java
+++ b/guava-tests/test/com/google/common/net/InetAddressesTest.java
@@ -135,6 +135,20 @@ public void testForStringIPv4Input() throws UnknownHostException {
     assertTrue(InetAddresses.isInetAddress(ipStr));
   }
 
+  public void testForStringIPv4NonAsciiInput() throws UnknownHostException {
+    String ipStr = "૧૯૨.૧૬૮.૦.૧"; // 192.168.0.1 in Gujarati digits
+    // Shouldn't hit DNS, because it's an IP string literal.
+    InetAddress ipv4Addr;
+    try {
+      ipv4Addr = InetAddress.getByName(ipStr);
+    } catch (UnknownHostException e) {
+      // OK: this is probably Android, which is stricter.
+      return;
+    }
+    assertEquals(ipv4Addr, InetAddresses.forString(ipStr));
+    assertTrue(InetAddresses.isInetAddress(ipStr));
+  }
+
   public void testForStringIPv6Input() throws UnknownHostException {
     String ipStr = "3ffe::1";
     // Shouldn't hit DNS, because it's an IP string literal.
@@ -143,6 +157,20 @@ public void testForStringIPv6Input() throws UnknownHostException {
     assertTrue(InetAddresses.isInetAddress(ipStr));
   }
 
+  public void testForStringIPv6NonAsciiInput() throws UnknownHostException {
+    String ipStr = "૩ffe::૧"; // 3ffe::1 with Gujarati digits for 3 and 1
+    // Shouldn't hit DNS, because it's an IP string literal.
+    InetAddress ipv6Addr;
+    try {
+      ipv6Addr = InetAddress.getByName(ipStr);
+    } catch (UnknownHostException e) {
+      // OK: this is probably Android, which is stricter.
+      return;
+    }
+    assertEquals(ipv6Addr, InetAddresses.forString(ipStr));
+    assertTrue(InetAddresses.isInetAddress(ipStr));
+  }
+
   public void testForStringIPv6EightColons() throws UnknownHostException {
     ImmutableSet<String> eightColons =
         ImmutableSet.of("::7:6:5:4:3:2:1", "::7:6:5:4:3:2:0", "7:6:5:4:3:2:1::", "0:6:5:4:3:2:1::");
diff --git a/guava-tests/test/com/google/common/net/InternetDomainNameTest.java b/guava-tests/test/com/google/common/net/InternetDomainNameTest.java
index 7113fb45741a..c440ee53f509 100644
--- a/guava-tests/test/com/google/common/net/InternetDomainNameTest.java
+++ b/guava-tests/test/com/google/common/net/InternetDomainNameTest.java
@@ -232,7 +232,7 @@ public final class InternetDomainNameTest extends TestCase {
 
   public void testValid() {
     for (String name : VALID_NAME) {
-      InternetDomainName.from(name);
+      InternetDomainName unused = InternetDomainName.from(name);
     }
   }
 
@@ -392,7 +392,7 @@ public void testParentChild() {
     // These would throw an exception if leniency were not preserved during parent() and child()
     // calls.
     InternetDomainName child = parent.child(LOTS_OF_DELTAS);
-    child.child(LOTS_OF_DELTAS);
+    InternetDomainName unused = child.child(LOTS_OF_DELTAS);
   }
 
   public void testValidTopPrivateDomain() {
diff --git a/guava-tests/test/com/google/common/net/MediaTypeTest.java b/guava-tests/test/com/google/common/net/MediaTypeTest.java
index cec3cdd28cce..574db68e80b3 100644
--- a/guava-tests/test/com/google/common/net/MediaTypeTest.java
+++ b/guava-tests/test/com/google/common/net/MediaTypeTest.java
@@ -46,7 +46,6 @@
 import com.google.common.testing.NullPointerTester;
 import java.lang.reflect.Field;
 import java.nio.charset.Charset;
-import java.nio.charset.IllegalCharsetNameException;
 import java.nio.charset.UnsupportedCharsetException;
 import java.util.Arrays;
 import junit.framework.TestCase;
@@ -537,7 +536,7 @@ public void testGetCharset_illegalCharset() {
     try {
       mediaType.charset();
       fail();
-    } catch (IllegalCharsetNameException expected) {
+    } catch (IllegalArgumentException expected) {
     }
   }
 
diff --git a/guava-tests/test/com/google/common/net/PercentEscaperTest.java b/guava-tests/test/com/google/common/net/PercentEscaperTest.java
index 8443680e7f11..e600e4c7c1af 100644
--- a/guava-tests/test/com/google/common/net/PercentEscaperTest.java
+++ b/guava-tests/test/com/google/common/net/PercentEscaperTest.java
@@ -120,16 +120,11 @@ public void testBadArguments_badchars() {
     }
   }
 
-  /**
-   * Tests that if space is a safe character you cannot also specify 'plusForSpace' (throws {@link
-   * IllegalArgumentException}).
-   */
   public void testBadArguments_plusforspace() {
-    try {
-      new PercentEscaper(" ", false);
-    } catch (IllegalArgumentException e) {
-      fail("Space can be a 'safe' character if plusForSpace is false");
-    }
+    // space can be a safe char if plusForSpace is false
+    PercentEscaper unused = new PercentEscaper(" ", false);
+
+    // space cannot be a safe char is plusForSpace is true
     String msg = "plusForSpace cannot be specified when space is a 'safe' character";
     try {
       new PercentEscaper(" ", true);
diff --git a/guava-tests/test/com/google/common/primitives/BooleansTest.java b/guava-tests/test/com/google/common/primitives/BooleansTest.java
index 560c33700382..43ec04c4a4a4 100644
--- a/guava-tests/test/com/google/common/primitives/BooleansTest.java
+++ b/guava-tests/test/com/google/common/primitives/BooleansTest.java
@@ -299,7 +299,8 @@ public void testAsListEquals() {
     assertEquals(1, Booleans.asList(ARRAY_FALSE_TRUE).lastIndexOf(true));
     List<Boolean> reference = Booleans.asList(ARRAY_FALSE);
     assertEquals(Booleans.asList(ARRAY_FALSE), reference);
-    assertEquals(reference, reference);
+    // Explicitly call `equals`; `assertEquals` might return fast
+    assertTrue(reference.equals(reference));
   }
 
   public void testAsListHashcode() {
diff --git a/guava-tests/test/com/google/common/primitives/UnsignedLongTest.java b/guava-tests/test/com/google/common/primitives/UnsignedLongTest.java
index dd2a8ab88bfc..cfa2862573aa 100644
--- a/guava-tests/test/com/google/common/primitives/UnsignedLongTest.java
+++ b/guava-tests/test/com/google/common/primitives/UnsignedLongTest.java
@@ -36,13 +36,23 @@ public class UnsignedLongTest extends TestCase {
   static {
     ImmutableSet.Builder<Long> testLongsBuilder = ImmutableSet.builder();
     ImmutableSet.Builder<BigInteger> testBigIntegersBuilder = ImmutableSet.builder();
+
+    // The values here look like 111...11101...010 in binary, where the initial 111...1110 takes
+    // up exactly as many bits as can be represented in the significand (24 for float, 53 for
+    // double). That final 0 should be rounded up to 1 because the remaining bits make that number
+    // slightly nearer.
+    long floatConversionTest = 0xfffffe8000000002L;
+    long doubleConversionTest = 0xfffffffffffff402L;
+
     for (long i = -3; i <= 3; i++) {
       testLongsBuilder
           .add(i)
           .add(Long.MAX_VALUE + i)
           .add(Long.MIN_VALUE + i)
           .add(Integer.MIN_VALUE + i)
-          .add(Integer.MAX_VALUE + i);
+          .add(Integer.MAX_VALUE + i)
+          .add(floatConversionTest + i)
+          .add(doubleConversionTest + i);
       BigInteger bigI = BigInteger.valueOf(i);
       testBigIntegersBuilder
           .add(bigI)
@@ -130,17 +140,26 @@ public void testToStringRadixQuick() {
     }
   }
 
+  @AndroidIncompatible // b/28251030, re-enable when the fix is everywhere we run this test
   public void testFloatValue() {
     for (long value : TEST_LONGS) {
       UnsignedLong unsignedValue = UnsignedLong.fromLongBits(value);
-      assertEquals(unsignedValue.bigIntegerValue().floatValue(), unsignedValue.floatValue());
+      assertEquals(
+          "Float value of " + unsignedValue,
+          unsignedValue.bigIntegerValue().floatValue(),
+          unsignedValue.floatValue(),
+          0.0f);
     }
   }
 
   public void testDoubleValue() {
     for (long value : TEST_LONGS) {
       UnsignedLong unsignedValue = UnsignedLong.fromLongBits(value);
-      assertEquals(unsignedValue.bigIntegerValue().doubleValue(), unsignedValue.doubleValue());
+      assertEquals(
+          "Double value of " + unsignedValue,
+          unsignedValue.bigIntegerValue().doubleValue(),
+          unsignedValue.doubleValue(),
+          0.0);
     }
   }
 
diff --git a/guava-tests/test/com/google/common/reflect/ElementTest.java b/guava-tests/test/com/google/common/reflect/ElementTest.java
deleted file mode 100644
index abe63ba56163..000000000000
--- a/guava-tests/test/com/google/common/reflect/ElementTest.java
+++ /dev/null
@@ -1,247 +0,0 @@
-/*
- * Copyright (C) 2012 The Guava Authors
- *
- * Licensed under the Apache License, Version 2.0 (the "License");
- * you may not use this file except in compliance with the License.
- * You may obtain a copy of the License at
- *
- * http://www.apache.org/licenses/LICENSE-2.0
- *
- * Unless required by applicable law or agreed to in writing, software
- * distributed under the License is distributed on an "AS IS" BASIS,
- * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
- * See the License for the specific language governing permissions and
- * limitations under the License.
- */
-
-package com.google.common.reflect;
-
-import com.google.common.testing.EqualsTester;
-import com.google.common.testing.NullPointerTester;
-import java.lang.annotation.Retention;
-import java.lang.annotation.RetentionPolicy;
-import java.lang.reflect.Constructor;
-import junit.framework.TestCase;
-
-/**
- * Unit tests of {@link Element}.
- *
- * @author Ben Yu
- */
-public class ElementTest extends TestCase {
-
-  public void testPrivateField() throws Exception {
-    Element element = A.field("privateField");
-    assertTrue(element.isPrivate());
-    assertFalse(element.isAbstract());
-    assertFalse(element.isPackagePrivate());
-    assertFalse(element.isProtected());
-    assertFalse(element.isPublic());
-    assertFalse(element.isFinal());
-    assertFalse(element.isStatic());
-    assertTrue(element.isAnnotationPresent(Tested.class));
-  }
-
-  public void testPackagePrivateField() throws Exception {
-    Element element = A.field("packagePrivateField");
-    assertFalse(element.isPrivate());
-    assertTrue(element.isPackagePrivate());
-    assertFalse(element.isProtected());
-    assertFalse(element.isPublic());
-    assertFalse(element.isFinal());
-    assertFalse(element.isStatic());
-    assertTrue(element.isAnnotationPresent(Tested.class));
-  }
-
-  public void testProtectedField() throws Exception {
-    Element element = A.field("protectedField");
-    assertFalse(element.isPrivate());
-    assertFalse(element.isPackagePrivate());
-    assertTrue(element.isProtected());
-    assertFalse(element.isPublic());
-    assertFalse(element.isFinal());
-    assertFalse(element.isStatic());
-    assertTrue(element.isAnnotationPresent(Tested.class));
-  }
-
-  public void testPublicField() throws Exception {
-    Element element = A.field("publicField");
-    assertFalse(element.isPrivate());
-    assertFalse(element.isPackagePrivate());
-    assertFalse(element.isProtected());
-    assertTrue(element.isPublic());
-    assertFalse(element.isFinal());
-    assertFalse(element.isStatic());
-    assertTrue(element.isAnnotationPresent(Tested.class));
-  }
-
-  public void testFinalField() throws Exception {
-    Element element = A.field("finalField");
-    assertTrue(element.isFinal());
-    assertFalse(element.isStatic());
-    assertTrue(element.isAnnotationPresent(Tested.class));
-  }
-
-  public void testStaticField() throws Exception {
-    Element element = A.field("staticField");
-    assertTrue(element.isStatic());
-    assertTrue(element.isAnnotationPresent(Tested.class));
-  }
-
-  public void testVolatileField() throws Exception {
-    Element element = A.field("volatileField");
-    assertTrue(element.isVolatile());
-  }
-
-  public void testTransientField() throws Exception {
-    Element element = A.field("transientField");
-    assertTrue(element.isTransient());
-  }
-
-  public void testConstructor() throws Exception {
-    Element element = A.constructor();
-    assertTrue(element.isPublic());
-    assertFalse(element.isPackagePrivate());
-    assertFalse(element.isAbstract());
-    assertFalse(element.isStatic());
-    assertTrue(element.isAnnotationPresent(Tested.class));
-  }
-
-  public void testAbstractMethod() throws Exception {
-    Element element = A.method("abstractMethod");
-    assertTrue(element.isPackagePrivate());
-    assertTrue(element.isAbstract());
-    assertFalse(element.isFinal());
-    assertTrue(element.isAnnotationPresent(Tested.class));
-  }
-
-  public void testOverridableMethod() throws Exception {
-    Element element = A.method("overridableMethod");
-    assertTrue(element.isPackagePrivate());
-    assertFalse(element.isAbstract());
-    assertFalse(element.isFinal());
-    assertTrue(element.isAnnotationPresent(Tested.class));
-  }
-
-  public void testPrivateMethod() throws Exception {
-    Element element = A.method("privateMethod");
-    assertFalse(element.isAbstract());
-    assertTrue(element.isPrivate());
-    assertFalse(element.isPackagePrivate());
-    assertFalse(element.isPublic());
-    assertFalse(element.isProtected());
-    assertTrue(element.isAnnotationPresent(Tested.class));
-  }
-
-  public void testProtectedMethod() throws Exception {
-    Element element = A.method("protectedMethod");
-    assertFalse(element.isAbstract());
-    assertFalse(element.isPrivate());
-    assertFalse(element.isPackagePrivate());
-    assertFalse(element.isFinal());
-    assertFalse(element.isPublic());
-    assertTrue(element.isProtected());
-    assertTrue(element.isAnnotationPresent(Tested.class));
-  }
-
-  public void testFinalMethod() throws Exception {
-    Element element = A.method("publicFinalMethod");
-    assertFalse(element.isAbstract());
-    assertFalse(element.isPrivate());
-    assertTrue(element.isFinal());
-    assertTrue(element.isPublic());
-    assertTrue(element.isAnnotationPresent(Tested.class));
-  }
-
-  public void testNativeMethod() throws Exception {
-    Element element = A.method("nativeMethod");
-    assertTrue(element.isNative());
-    assertTrue(element.isPackagePrivate());
-  }
-
-  public void testSynchronizedMethod() throws Exception {
-    Element element = A.method("synchronizedMethod");
-    assertTrue(element.isSynchronized());
-  }
-
-  public void testUnannotatedMethod() throws Exception {
-    Element element = A.method("notAnnotatedMethod");
-    assertFalse(element.isAnnotationPresent(Tested.class));
-  }
-
-  public void testEquals() throws Exception {
-    new EqualsTester()
-        .addEqualityGroup(A.field("privateField"), A.field("privateField"))
-        .addEqualityGroup(A.field("publicField"))
-        .addEqualityGroup(A.constructor(), A.constructor())
-        .addEqualityGroup(A.method("privateMethod"), A.method("privateMethod"))
-        .addEqualityGroup(A.method("publicFinalMethod"))
-        .testEquals();
-  }
-
-  public void testNulls() {
-    new NullPointerTester().testAllPublicStaticMethods(Element.class);
-  }
-
-  @Retention(RetentionPolicy.RUNTIME)
-  private @interface Tested {}
-
-  private abstract static class A {
-    @Tested private boolean privateField;
-    @Tested int packagePrivateField;
-    @Tested protected int protectedField;
-    @Tested public String publicField;
-    @Tested private static Iterable<String> staticField;
-    @Tested private final Object finalField;
-    private volatile char volatileField;
-    private transient long transientField;
-
-    @Tested
-    public A(Object finalField) {
-      this.finalField = finalField;
-    }
-
-    @Tested
-    abstract void abstractMethod();
-
-    @Tested
-    void overridableMethod() {}
-
-    @Tested
-    protected void protectedMethod() {}
-
-    @Tested
-    private void privateMethod() {}
-
-    @Tested
-    public final void publicFinalMethod() {}
-
-    void notAnnotatedMethod() {}
-
-    static Element field(String name) throws Exception {
-      Element element = new Element(A.class.getDeclaredField(name));
-      assertEquals(name, element.getName());
-      assertEquals(A.class, element.getDeclaringClass());
-      return element;
-    }
-
-    static Element constructor() throws Exception {
-      Constructor<?> constructor = A.class.getDeclaredConstructor(Object.class);
-      Element element = new Element(constructor);
-      assertEquals(constructor.getName(), element.getName());
-      assertEquals(A.class, element.getDeclaringClass());
-      return element;
-    }
-
-    static Element method(String name, Class<?>... parameterTypes) throws Exception {
-      Element element = new Element(A.class.getDeclaredMethod(name, parameterTypes));
-      assertEquals(name, element.getName());
-      assertEquals(A.class, element.getDeclaringClass());
-      return element;
-    }
-
-    native void nativeMethod();
-
-    synchronized void synchronizedMethod() {}
-  }
-}
diff --git a/guava-tests/test/com/google/common/reflect/InvokableTest.java b/guava-tests/test/com/google/common/reflect/InvokableTest.java
index 1b48ba673035..5e15d664373c 100644
--- a/guava-tests/test/com/google/common/reflect/InvokableTest.java
+++ b/guava-tests/test/com/google/common/reflect/InvokableTest.java
@@ -19,13 +19,16 @@
 import static com.google.common.truth.Truth.assertThat;
 
 import com.google.common.collect.ImmutableList;
+import com.google.common.collect.ImmutableSet;
 import com.google.common.collect.Iterables;
 import com.google.common.testing.EqualsTester;
 import com.google.common.testing.NullPointerTester;
 import java.lang.annotation.Retention;
 import java.lang.annotation.RetentionPolicy;
+import java.lang.reflect.AccessibleObject;
 import java.lang.reflect.Constructor;
 import java.lang.reflect.Method;
+import java.lang.reflect.Modifier;
 import java.lang.reflect.ParameterizedType;
 import java.lang.reflect.TypeVariable;
 import java.util.Collections;
@@ -39,6 +42,180 @@
  */
 @AndroidIncompatible // lots of failures, possibly some related to bad equals() implementations?
 public class InvokableTest extends TestCase {
+  // Historically Invokable inherited from java.lang.reflect.AccessibleObject. That's no longer the
+  // case, but we do check that its API still has the same public methods. We exclude some methods
+  // that were added in Java 9 and that people probably weren't calling via Invokable, namely
+  // `boolean canAccess(Object)` and `boolean trySetAccessible()`.
+  public void testApiCompatibleWithAccessibleObject() {
+    ImmutableSet<String> invokableMethods =
+        publicMethodSignatures(Invokable.class, ImmutableSet.<String>of());
+    ImmutableSet<String> accesibleObjectMethods =
+        publicMethodSignatures(AccessibleObject.class, ImmutableSet.of("canAccess"));
+    assertThat(invokableMethods).containsAtLeastElementsIn(accesibleObjectMethods);
+    Class<?> genericDeclaration;
+    try {
+      genericDeclaration = Class.forName("java.lang.reflect.GenericDeclaration");
+      ImmutableSet<String> genericDeclarationMethods =
+          publicMethodSignatures(genericDeclaration, ImmutableSet.<String>of());
+      assertThat(invokableMethods).containsAtLeastElementsIn(genericDeclarationMethods);
+    } catch (ClassNotFoundException e) {
+      // OK: we're on Java 7, which doesn't have this class
+    }
+  }
+
+  private static ImmutableSet<String> publicMethodSignatures(
+      Class<?> c, ImmutableSet<String> ignore) {
+    ImmutableSet.Builder<String> methods = ImmutableSet.builder();
+    for (Method method : c.getMethods()) {
+      if (Modifier.isStatic(method.getModifiers()) || ignore.contains(method.getName())) {
+        continue;
+      }
+      StringBuilder signature =
+          new StringBuilder()
+              .append(typeName(method.getReturnType()))
+              .append(" ")
+              .append(method.getName())
+              .append("(");
+      String sep = "";
+      for (Class<?> param : method.getParameterTypes()) {
+        signature.append(sep).append(typeName(param));
+        sep = ", ";
+      }
+      methods.add(signature.append(")").toString());
+    }
+    return methods.build();
+  }
+
+  private static String typeName(Class<?> type) {
+    return type.isArray() ? typeName(type.getComponentType()) + "[]" : type.getName();
+  }
+
+  public void testConstructor() throws Exception {
+    Invokable<A, A> invokable = A.constructor();
+    assertTrue(invokable.isPublic());
+    assertFalse(invokable.isPackagePrivate());
+    assertFalse(invokable.isAbstract());
+    assertFalse(invokable.isStatic());
+    assertTrue(invokable.isAnnotationPresent(Tested.class));
+  }
+
+  public void testAbstractMethod() throws Exception {
+    Invokable<?, Object> invokable = A.method("abstractMethod");
+    assertTrue(invokable.isPackagePrivate());
+    assertTrue(invokable.isAbstract());
+    assertFalse(invokable.isFinal());
+    assertTrue(invokable.isAnnotationPresent(Tested.class));
+  }
+
+  public void testOverridableMethod() throws Exception {
+    Invokable<?, Object> invokable = A.method("overridableMethod");
+    assertTrue(invokable.isPackagePrivate());
+    assertFalse(invokable.isAbstract());
+    assertFalse(invokable.isFinal());
+    assertTrue(invokable.isAnnotationPresent(Tested.class));
+  }
+
+  public void testPrivateMethod() throws Exception {
+    Invokable<?, Object> invokable = A.method("privateMethod");
+    assertFalse(invokable.isAbstract());
+    assertTrue(invokable.isPrivate());
+    assertFalse(invokable.isPackagePrivate());
+    assertFalse(invokable.isPublic());
+    assertFalse(invokable.isProtected());
+    assertTrue(invokable.isAnnotationPresent(Tested.class));
+  }
+
+  public void testProtectedMethod() throws Exception {
+    Invokable<?, Object> invokable = A.method("protectedMethod");
+    assertFalse(invokable.isAbstract());
+    assertFalse(invokable.isPrivate());
+    assertFalse(invokable.isPackagePrivate());
+    assertFalse(invokable.isFinal());
+    assertFalse(invokable.isPublic());
+    assertTrue(invokable.isProtected());
+    assertTrue(invokable.isAnnotationPresent(Tested.class));
+  }
+
+  public void testFinalMethod() throws Exception {
+    Invokable<?, Object> invokable = A.method("publicFinalMethod");
+    assertFalse(invokable.isAbstract());
+    assertFalse(invokable.isPrivate());
+    assertTrue(invokable.isFinal());
+    assertTrue(invokable.isPublic());
+    assertTrue(invokable.isAnnotationPresent(Tested.class));
+  }
+
+  public void testNativeMethod() throws Exception {
+    Invokable<?, Object> invokable = A.method("nativeMethod");
+    assertTrue(invokable.isNative());
+    assertTrue(invokable.isPackagePrivate());
+  }
+
+  public void testSynchronizedMethod() throws Exception {
+    Invokable<?, Object> invokable = A.method("synchronizedMethod");
+    assertTrue(invokable.isSynchronized());
+  }
+
+  public void testUnannotatedMethod() throws Exception {
+    Invokable<?, Object> invokable = A.method("notAnnotatedMethod");
+    assertFalse(invokable.isAnnotationPresent(Tested.class));
+  }
+
+  @Retention(RetentionPolicy.RUNTIME)
+  private @interface Tested {}
+
+  private abstract static class A {
+    @Tested private boolean privateField;
+    @Tested int packagePrivateField;
+    @Tested protected int protectedField;
+    @Tested public String publicField;
+    @Tested private static Iterable<String> staticField;
+    @Tested private final Object finalField;
+    private volatile char volatileField;
+    private transient long transientField;
+
+    @Tested
+    public A(Object finalField) {
+      this.finalField = finalField;
+    }
+
+    @Tested
+    abstract void abstractMethod();
+
+    @Tested
+    void overridableMethod() {}
+
+    @Tested
+    protected void protectedMethod() {}
+
+    @Tested
+    private void privateMethod() {}
+
+    @Tested
+    public final void publicFinalMethod() {}
+
+    void notAnnotatedMethod() {}
+
+    static Invokable<A, A> constructor() throws Exception {
+      Constructor<A> constructor = A.class.getDeclaredConstructor(Object.class);
+      Invokable<A, A> invokable = Invokable.from(constructor);
+      assertEquals(constructor.getName(), invokable.getName());
+      assertEquals(A.class, invokable.getDeclaringClass());
+      return invokable;
+    }
+
+    static Invokable<?, Object> method(String name, Class<?>... parameterTypes) throws Exception {
+      Invokable<?, Object> invokable =
+          Invokable.from(A.class.getDeclaredMethod(name, parameterTypes));
+      assertEquals(name, invokable.getName());
+      assertEquals(A.class, invokable.getDeclaringClass());
+      return invokable;
+    }
+
+    native void nativeMethod();
+
+    synchronized void synchronizedMethod() {}
+  }
 
   public void testConstructor_returnType() throws Exception {
     assertEquals(Prepender.class, Prepender.constructor().getReturnType().getType());
@@ -74,7 +251,7 @@ public void testConstructor_exceptionTypes() throws Exception {
   public void testConstructor_typeParameters() throws Exception {
     TypeVariable<?>[] variables = Prepender.constructor().getTypeParameters();
     assertThat(variables).hasLength(1);
-    assertEquals("A", variables[0].getName());
+    assertEquals("T", variables[0].getName());
   }
 
   public void testConstructor_parameters() throws Exception {
@@ -424,7 +601,7 @@ public void run() {
   }
 
   public void testAnonymousClassInConstructor() {
-    new AnonymousClassInConstructor();
+    AnonymousClassInConstructor unused = new AnonymousClassInConstructor();
   }
 
   private static class AnonymousClassInConstructor {
@@ -444,7 +621,7 @@ public void run() {
   }
 
   public void testLocalClassInInstanceInitializer() {
-    new LocalClassInInstanceInitializer();
+    LocalClassInInstanceInitializer unused = new LocalClassInInstanceInitializer();
   }
 
   private static class LocalClassInInstanceInitializer {
@@ -456,7 +633,7 @@ class Local {}
   }
 
   public void testLocalClassInStaticInitializer() {
-    new LocalClassInStaticInitializer();
+    LocalClassInStaticInitializer unused = new LocalClassInStaticInitializer();
   }
 
   private static class LocalClassInStaticInitializer {
@@ -468,7 +645,8 @@ class Local {}
   }
 
   public void testLocalClassWithSeeminglyHiddenThisInStaticInitializer_BUG() {
-    new LocalClassWithSeeminglyHiddenThisInStaticInitializer();
+    LocalClassWithSeeminglyHiddenThisInStaticInitializer unused =
+        new LocalClassWithSeeminglyHiddenThisInStaticInitializer();
   }
 
   /**
@@ -530,6 +708,9 @@ class LocalWithGenericConstructorParameter {
 
   public void testEquals() throws Exception {
     new EqualsTester()
+        .addEqualityGroup(A.constructor(), A.constructor())
+        .addEqualityGroup(A.method("privateMethod"), A.method("privateMethod"))
+        .addEqualityGroup(A.method("publicFinalMethod"))
         .addEqualityGroup(Prepender.constructor(), Prepender.constructor())
         .addEqualityGroup(Prepender.constructor(String.class, int.class))
         .addEqualityGroup(Prepender.method("privateMethod"), Prepender.method("privateMethod"))
@@ -562,7 +743,7 @@ private static class Prepender {
     }
 
     // just for testing
-    private <A> Prepender() {
+    private <T> Prepender() {
       this(null, 0);
     }
 
diff --git a/guava-tests/test/com/google/common/reflect/TypeTokenTest.java b/guava-tests/test/com/google/common/reflect/TypeTokenTest.java
index 171ef49fdb80..79732090a132 100644
--- a/guava-tests/test/com/google/common/reflect/TypeTokenTest.java
+++ b/guava-tests/test/com/google/common/reflect/TypeTokenTest.java
@@ -402,7 +402,7 @@ public <T> void testGetGenericSuperclass_typeVariable_unbounded() {
     assertEquals(TypeToken.of(Object.class), new TypeToken<T[]>() {}.getGenericSuperclass());
   }
 
-  public <T extends ArrayList<String> & CharSequence>
+  public <T extends ArrayList<String> & Serializable>
       void testGetGenericSuperclass_typeVariable_boundIsClass() {
     assertEquals(
         new TypeToken<ArrayList<String>>() {},
@@ -410,7 +410,7 @@ void testGetGenericSuperclass_typeVariable_boundIsClass() {
     assertEquals(TypeToken.of(Object.class), new TypeToken<T[]>() {}.getGenericSuperclass());
   }
 
-  public <T extends Enum<T> & CharSequence>
+  public <T extends Enum<T> & Serializable>
       void testGetGenericSuperclass_typeVariable_boundIsFBoundedClass() {
     assertEquals(
         new TypeToken<Enum<T>>() {},
@@ -418,13 +418,13 @@ void testGetGenericSuperclass_typeVariable_boundIsFBoundedClass() {
     assertEquals(TypeToken.of(Object.class), new TypeToken<T[]>() {}.getGenericSuperclass());
   }
 
-  public <T extends List<String> & CharSequence>
+  public <T extends List<String> & Serializable>
       void testGetGenericSuperclass_typeVariable_boundIsInterface() {
     assertNull(TypeToken.of(new TypeCapture<T>() {}.capture()).getGenericSuperclass());
     assertEquals(TypeToken.of(Object.class), new TypeToken<T[]>() {}.getGenericSuperclass());
   }
 
-  public <T extends ArrayList<String> & CharSequence, T1 extends T>
+  public <T extends ArrayList<String> & Serializable, T1 extends T>
       void testGetGenericSuperclass_typeVariable_boundIsTypeVariableAndClass() {
     assertEquals(
         TypeToken.of(new TypeCapture<T>() {}.capture()),
@@ -432,7 +432,7 @@ void testGetGenericSuperclass_typeVariable_boundIsTypeVariableAndClass() {
     assertEquals(TypeToken.of(Object.class), new TypeToken<T[]>() {}.getGenericSuperclass());
   }
 
-  public <T extends List<String> & CharSequence, T1 extends T>
+  public <T extends List<String> & Serializable, T1 extends T>
       void testGetGenericSuperclass_typeVariable_boundIsTypeVariableAndInterface() {
     assertNull(TypeToken.of(new TypeCapture<T1>() {}.capture()).getGenericSuperclass());
     assertEquals(TypeToken.of(Object.class), new TypeToken<T1[]>() {}.getGenericSuperclass());
@@ -1101,7 +1101,7 @@ public void testGetSupertype_withoutTypeVariable() {
   }
 
   public void testGetSupertype_chained() {
-    @SuppressWarnings("unchecked") // StringListIterable extensd ListIterable<String>
+    @SuppressWarnings("unchecked") // StringListIterable extends ListIterable<String>
     TypeToken<ListIterable<String>> listIterableType =
         (TypeToken<ListIterable<String>>)
             TypeToken.of(StringListIterable.class).getSupertype(ListIterable.class);
@@ -1793,7 +1793,7 @@ private abstract static class RawTypeConsistencyTester<T extends Enum<T> & CharS
 
     abstract <T2 extends CharSequence & Iterable<T2>> void acceptT2(T2 t2);
 
-    static void verifyConsitentRawType() {
+    static void verifyConsistentRawType() {
       for (Method method : RawTypeConsistencyTester.class.getDeclaredMethods()) {
         assertEquals(
             method.getReturnType(), TypeToken.of(method.getGenericReturnType()).getRawType());
@@ -1807,7 +1807,7 @@ static void verifyConsitentRawType() {
   }
 
   public void testRawTypes() {
-    RawTypeConsistencyTester.verifyConsitentRawType();
+    RawTypeConsistencyTester.verifyConsistentRawType();
     assertEquals(Object.class, TypeToken.of(Types.subtypeOf(Object.class)).getRawType());
     assertEquals(
         CharSequence.class, TypeToken.of(Types.subtypeOf(CharSequence.class)).getRawType());
diff --git a/guava-tests/test/com/google/common/util/concurrent/AbstractAbstractFutureTest.java b/guava-tests/test/com/google/common/util/concurrent/AbstractAbstractFutureTest.java
index f49b96245db4..991cada29a11 100644
--- a/guava-tests/test/com/google/common/util/concurrent/AbstractAbstractFutureTest.java
+++ b/guava-tests/test/com/google/common/util/concurrent/AbstractAbstractFutureTest.java
@@ -359,7 +359,6 @@ public void testNegativeTimeout() throws Exception {
   }
 
   @GwtIncompatible // threads
-
   public void testOverflowTimeout() throws Exception {
     // First, sanity check that naive multiplication would really overflow to a negative number:
     long nanosPerSecond = NANOSECONDS.convert(1, SECONDS);
diff --git a/guava-tests/test/com/google/common/util/concurrent/ClosingFutureTest.java b/guava-tests/test/com/google/common/util/concurrent/AbstractClosingFutureTest.java
similarity index 91%
rename from guava-tests/test/com/google/common/util/concurrent/ClosingFutureTest.java
rename to guava-tests/test/com/google/common/util/concurrent/AbstractClosingFutureTest.java
index ab0e5f8d69b8..ecccd784cf4c 100644
--- a/guava-tests/test/com/google/common/util/concurrent/ClosingFutureTest.java
+++ b/guava-tests/test/com/google/common/util/concurrent/AbstractClosingFutureTest.java
@@ -81,7 +81,7 @@
  * ClosingFuture#finishToValueAndCloser(ValueAndCloserConsumer, Executor)} paths to complete a
  * {@link ClosingFuture} pipeline.
  */
-public abstract class ClosingFutureTest extends TestCase {
+public abstract class AbstractClosingFutureTest extends TestCase {
   // TODO(dpb): Use Expect once that supports JUnit 3, or we can use JUnit 4.
   final List<AssertionError> failures = new ArrayList<>();
   final StandardSubjectBuilder expect =
@@ -1633,7 +1633,7 @@ public Closeable call(DeferredCloser closer) throws Exception {
 
   /**
    * Marks the given step final and waits for it to fail. Expects the failure exception to match
-   * {@link ClosingFutureTest#exception}.
+   * {@link AbstractClosingFutureTest#exception}.
    */
   abstract void assertFinallyFailsWithException(ClosingFuture<?> closingFuture);
 
@@ -1645,191 +1645,6 @@ void waitUntilClosed(ClosingFuture<?> closingFuture) {
     assertTrue(awaitUninterruptibly(closingFuture.whenClosedCountDown(), 1, SECONDS));
   }
 
-  /** Tests for {@link ClosingFuture} that exercise {@link ClosingFuture#finishToFuture()}. */
-
-  public static class FinishToFutureTest extends ClosingFutureTest {
-
-    public void testFinishToFuture_throwsIfCalledTwice() throws Exception {
-      ClosingFuture<Closeable> closingFuture =
-          ClosingFuture.submit(
-              new ClosingCallable<Closeable>() {
-                @Override
-                public Closeable call(DeferredCloser closer) throws Exception {
-                  return closer.eventuallyClose(mockCloseable, executor);
-                }
-              },
-              executor);
-      FluentFuture<Closeable> unused = closingFuture.finishToFuture();
-      try {
-        FluentFuture<Closeable> unused2 = closingFuture.finishToFuture();
-        fail("should have thrown");
-      } catch (IllegalStateException expected) {
-      }
-    }
-
-    public void testFinishToFuture_throwsAfterCallingFinishToValueAndCloser() throws Exception {
-      ClosingFuture<Closeable> closingFuture =
-          ClosingFuture.submit(
-              new ClosingCallable<Closeable>() {
-                @Override
-                public Closeable call(DeferredCloser closer) throws Exception {
-                  return closer.eventuallyClose(mockCloseable, executor);
-                }
-              },
-              executor);
-      closingFuture.finishToValueAndCloser(new NoOpValueAndCloserConsumer<>(), directExecutor());
-      try {
-        FluentFuture<Closeable> unused = closingFuture.finishToFuture();
-        fail("should have thrown");
-      } catch (IllegalStateException expected) {
-      }
-    }
-
-    public void testFinishToFuture_preventsFurtherDerivation() {
-      ClosingFuture<String> closingFuture = ClosingFuture.from(immediateFuture("value1"));
-      FluentFuture<String> unused = closingFuture.finishToFuture();
-      assertDerivingThrowsIllegalStateException(closingFuture);
-    }
-
-    @Override
-    <T> T getFinalValue(ClosingFuture<T> closingFuture) throws ExecutionException {
-      return getUninterruptibly(closingFuture.finishToFuture());
-    }
-
-    @Override
-    void assertFinallyFailsWithException(ClosingFuture<?> closingFuture) {
-      assertThatFutureFailsWithException(closingFuture.finishToFuture());
-    }
-
-    @Override
-    void assertBecomesCanceled(ClosingFuture<?> closingFuture) throws ExecutionException {
-      assertThatFutureBecomesCancelled(closingFuture.finishToFuture());
-    }
-
-    @Override
-    void cancelFinalStepAndWait(ClosingFuture<TestCloseable> closingFuture) {
-      assertThat(closingFuture.finishToFuture().cancel(false)).isTrue();
-      waitUntilClosed(closingFuture);
-      futureCancelled.countDown();
-    }
-  }
-
-  /**
-   * Tests for {@link ClosingFuture} that exercise {@link
-   * ClosingFuture#finishToValueAndCloser(ValueAndCloserConsumer, Executor)}.
-   */
-
-  public static class FinishToValueAndCloserTest extends ClosingFutureTest {
-
-    private final ExecutorService finishToValueAndCloserExecutor = newSingleThreadExecutor();
-    private volatile ValueAndCloser<?> valueAndCloser;
-
-    @Override
-    protected void tearDown() throws Exception {
-      super.tearDown();
-      assertWithMessage("finishToValueAndCloserExecutor was shut down")
-          .that(shutdownAndAwaitTermination(finishToValueAndCloserExecutor, 10, SECONDS))
-          .isTrue();
-    }
-
-    public void testFinishToValueAndCloser_throwsIfCalledTwice() throws Exception {
-      ClosingFuture<Closeable> closingFuture =
-          ClosingFuture.submit(
-              new ClosingCallable<Closeable>() {
-                @Override
-                public Closeable call(DeferredCloser closer) throws Exception {
-                  return closer.eventuallyClose(mockCloseable, executor);
-                }
-              },
-              executor);
-      closingFuture.finishToValueAndCloser(
-          new NoOpValueAndCloserConsumer<>(), finishToValueAndCloserExecutor);
-      try {
-        closingFuture.finishToValueAndCloser(
-            new NoOpValueAndCloserConsumer<>(), finishToValueAndCloserExecutor);
-        fail("should have thrown");
-      } catch (IllegalStateException expected) {
-      }
-    }
-
-    public void testFinishToValueAndCloser_throwsAfterCallingFinishToFuture() throws Exception {
-      ClosingFuture<Closeable> closingFuture =
-          ClosingFuture.submit(
-              new ClosingCallable<Closeable>() {
-                @Override
-                public Closeable call(DeferredCloser closer) throws Exception {
-                  return closer.eventuallyClose(mockCloseable, executor);
-                }
-              },
-              executor);
-      FluentFuture<Closeable> unused = closingFuture.finishToFuture();
-      try {
-        closingFuture.finishToValueAndCloser(
-            new NoOpValueAndCloserConsumer<>(), finishToValueAndCloserExecutor);
-        fail("should have thrown");
-      } catch (IllegalStateException expected) {
-      }
-    }
-
-    @Override
-    <T> T getFinalValue(ClosingFuture<T> closingFuture) throws ExecutionException {
-      return finishToValueAndCloser(closingFuture).get();
-    }
-
-    @Override
-    void assertFinallyFailsWithException(ClosingFuture<?> closingFuture) {
-      assertThatFutureFailsWithException(closingFuture.statusFuture());
-      ValueAndCloser<?> valueAndCloser = finishToValueAndCloser(closingFuture);
-      try {
-        valueAndCloser.get();
-        fail();
-      } catch (ExecutionException expected) {
-        assertThat(expected).hasCauseThat().isSameInstanceAs(exception);
-      }
-      valueAndCloser.closeAsync();
-    }
-
-    @Override
-    void assertBecomesCanceled(ClosingFuture<?> closingFuture) throws ExecutionException {
-      assertThatFutureBecomesCancelled(closingFuture.statusFuture());
-    }
-
-    @Override
-    void waitUntilClosed(ClosingFuture<?> closingFuture) {
-      if (valueAndCloser != null) {
-        valueAndCloser.closeAsync();
-      }
-      super.waitUntilClosed(closingFuture);
-    }
-
-    @Override
-    void cancelFinalStepAndWait(ClosingFuture<TestCloseable> closingFuture) {
-      assertThat(closingFuture.cancel(false)).isTrue();
-      ValueAndCloser<?> unused = finishToValueAndCloser(closingFuture);
-      waitUntilClosed(closingFuture);
-      futureCancelled.countDown();
-    }
-
-    private <V> ValueAndCloser<V> finishToValueAndCloser(ClosingFuture<V> closingFuture) {
-      final CountDownLatch valueAndCloserSet = new CountDownLatch(1);
-      closingFuture.finishToValueAndCloser(
-          new ValueAndCloserConsumer<V>() {
-            @Override
-            public void accept(ValueAndCloser<V> valueAndCloser) {
-              FinishToValueAndCloserTest.this.valueAndCloser = valueAndCloser;
-              valueAndCloserSet.countDown();
-            }
-          },
-          finishToValueAndCloserExecutor);
-      assertWithMessage("valueAndCloser was set")
-          .that(awaitUninterruptibly(valueAndCloserSet, 10, SECONDS))
-          .isTrue();
-      @SuppressWarnings("unchecked")
-      ValueAndCloser<V> valueAndCloserWithType = (ValueAndCloser<V>) valueAndCloser;
-      return valueAndCloserWithType;
-    }
-  }
-
   void assertThatFutureFailsWithException(Future<?> future) {
     try {
       getUninterruptibly(future);
@@ -1839,7 +1654,7 @@ void assertThatFutureFailsWithException(Future<?> future) {
     }
   }
 
-  private static void assertThatFutureBecomesCancelled(Future<?> future) throws ExecutionException {
+  static void assertThatFutureBecomesCancelled(Future<?> future) throws ExecutionException {
     try {
       getUninterruptibly(future);
       fail("Expected future to be canceled: " + future);
@@ -2006,7 +1821,7 @@ void awaitReturned() {
     }
   }
 
-  private static final class NoOpValueAndCloserConsumer<V> implements ValueAndCloserConsumer<V> {
+  static final class NoOpValueAndCloserConsumer<V> implements ValueAndCloserConsumer<V> {
     @Override
     public void accept(ValueAndCloser<V> valueAndCloser) {}
   }
diff --git a/guava-tests/test/com/google/common/util/concurrent/AbstractExecutionThreadServiceTest.java b/guava-tests/test/com/google/common/util/concurrent/AbstractExecutionThreadServiceTest.java
index 557fc0b5f2fe..9b3f0f86757f 100644
--- a/guava-tests/test/com/google/common/util/concurrent/AbstractExecutionThreadServiceTest.java
+++ b/guava-tests/test/com/google/common/util/concurrent/AbstractExecutionThreadServiceTest.java
@@ -68,7 +68,6 @@ protected final void tearDown() {
         thrownByExecutionThread);
   }
 
-
   public void testServiceStartStop() throws Exception {
     WaitOnRunService service = new WaitOnRunService();
     assertFalse(service.startUpCalled);
@@ -85,7 +84,6 @@ public void testServiceStartStop() throws Exception {
     executionThread.join();
   }
 
-
   public void testServiceStopIdempotence() throws Exception {
     WaitOnRunService service = new WaitOnRunService();
 
@@ -102,7 +100,6 @@ public void testServiceStopIdempotence() throws Exception {
     executionThread.join();
   }
 
-
   public void testServiceExitingOnItsOwn() throws Exception {
     WaitOnRunService service = new WaitOnRunService();
     service.expectedShutdownState = Service.State.RUNNING;
@@ -173,7 +170,6 @@ protected Executor executor() {
     }
   }
 
-
   public void testServiceThrowOnStartUp() throws Exception {
     ThrowOnStartUpService service = new ThrowOnStartUpService();
     assertFalse(service.startUpCalled);
@@ -212,7 +208,6 @@ protected Executor executor() {
     }
   }
 
-
   public void testServiceThrowOnRun() throws Exception {
     ThrowOnRunService service = new ThrowOnRunService();
 
@@ -229,7 +224,6 @@ public void testServiceThrowOnRun() throws Exception {
     assertEquals(Service.State.FAILED, service.state());
   }
 
-
   public void testServiceThrowOnRunAndThenAgainOnShutDown() throws Exception {
     ThrowOnRunService service = new ThrowOnRunService();
     service.throwOnShutDown = true;
@@ -271,7 +265,6 @@ protected Executor executor() {
     }
   }
 
-
   public void testServiceThrowOnShutDown() throws Exception {
     ThrowOnShutDown service = new ThrowOnShutDown();
 
@@ -331,7 +324,6 @@ public void execute(Runnable command) {}
     protected void run() throws Exception {}
   }
 
-
   public void testStopWhileStarting_runNotCalled() throws Exception {
     final CountDownLatch started = new CountDownLatch(1);
     FakeService service =
@@ -361,7 +353,6 @@ public void testStop_noStart() {
     assertEquals(0, service.shutdownCalled);
   }
 
-
   public void testDefaultService() throws InterruptedException {
     WaitOnRunService service = new WaitOnRunService();
     service.startAsync().awaitRunning();
diff --git a/guava-tests/test/com/google/common/util/concurrent/AbstractFutureCancellationCauseTest.java b/guava-tests/test/com/google/common/util/concurrent/AbstractFutureCancellationCauseTest.java
index 6c921b5b67d5..9aee78029f08 100644
--- a/guava-tests/test/com/google/common/util/concurrent/AbstractFutureCancellationCauseTest.java
+++ b/guava-tests/test/com/google/common/util/concurrent/AbstractFutureCancellationCauseTest.java
@@ -30,6 +30,7 @@
 import junit.framework.TestCase;
 
 /** Tests for {@link AbstractFuture} with the cancellation cause system property set */
+@AndroidIncompatible // custom classloading
 
 public class AbstractFutureCancellationCauseTest extends TestCase {
 
diff --git a/guava-tests/test/com/google/common/util/concurrent/AbstractFutureTest.java b/guava-tests/test/com/google/common/util/concurrent/AbstractFutureTest.java
index e55a31e725de..dc020fb20a0d 100644
--- a/guava-tests/test/com/google/common/util/concurrent/AbstractFutureTest.java
+++ b/guava-tests/test/com/google/common/util/concurrent/AbstractFutureTest.java
@@ -52,7 +52,6 @@
  *
  * @author Brian Stoler
  */
-
 public class AbstractFutureTest extends TestCase {
   public void testSuccess() throws ExecutionException, InterruptedException {
     final Object value = new Object();
@@ -292,6 +291,7 @@ public String pendingToString() {
    * derived from observing how much time actually passed for various operations.
    */
   @SuppressWarnings({"DeprecatedThreadMethods", "ThreadPriorityCheck"})
+  @AndroidIncompatible // Thread.suspend
   public void testToString_delayedTimeout() throws Exception {
     TimedWaiterThread thread =
         new TimedWaiterThread(new AbstractFuture<Object>() {}, 2, TimeUnit.SECONDS);
diff --git a/guava-tests/test/com/google/common/util/concurrent/AbstractIdleServiceTest.java b/guava-tests/test/com/google/common/util/concurrent/AbstractIdleServiceTest.java
index 7cad8b0fa712..2df5a4f3afa8 100644
--- a/guava-tests/test/com/google/common/util/concurrent/AbstractIdleServiceTest.java
+++ b/guava-tests/test/com/google/common/util/concurrent/AbstractIdleServiceTest.java
@@ -36,7 +36,6 @@ public class AbstractIdleServiceTest extends TestCase {
 
   // Functional tests using real thread. We only verify publicly visible state.
   // Interaction assertions are done by the single-threaded unit tests.
-
   public static class FunctionalTest extends TestCase {
 
     private static class DefaultService extends AbstractIdleService {
diff --git a/guava-tests/test/com/google/common/util/concurrent/AbstractScheduledServiceTest.java b/guava-tests/test/com/google/common/util/concurrent/AbstractScheduledServiceTest.java
index 158520b932ed..a05a838692b3 100644
--- a/guava-tests/test/com/google/common/util/concurrent/AbstractScheduledServiceTest.java
+++ b/guava-tests/test/com/google/common/util/concurrent/AbstractScheduledServiceTest.java
@@ -19,8 +19,11 @@
 import static com.google.common.truth.Truth.assertThat;
 import static com.google.common.util.concurrent.AbstractScheduledService.Scheduler.newFixedDelaySchedule;
 import static com.google.common.util.concurrent.MoreExecutors.directExecutor;
+import static java.util.concurrent.TimeUnit.MILLISECONDS;
+import static java.util.concurrent.TimeUnit.NANOSECONDS;
 import static java.util.concurrent.TimeUnit.SECONDS;
 
+import com.google.common.util.concurrent.AbstractScheduledService.Cancellable;
 import com.google.common.util.concurrent.AbstractScheduledService.Scheduler;
 import com.google.common.util.concurrent.Service.State;
 import com.google.common.util.concurrent.testing.TestingExecutors;
@@ -28,6 +31,7 @@
 import java.util.concurrent.CancellationException;
 import java.util.concurrent.CountDownLatch;
 import java.util.concurrent.CyclicBarrier;
+import java.util.concurrent.Delayed;
 import java.util.concurrent.Executors;
 import java.util.concurrent.Future;
 import java.util.concurrent.ScheduledExecutorService;
@@ -45,10 +49,9 @@
  *
  * @author Luke Sandberg
  */
-
 public class AbstractScheduledServiceTest extends TestCase {
 
-  volatile Scheduler configuration = newFixedDelaySchedule(0, 10, TimeUnit.MILLISECONDS);
+  volatile Scheduler configuration = newFixedDelaySchedule(0, 10, MILLISECONDS);
   volatile ScheduledFuture<?> future = null;
 
   volatile boolean atFixedRateCalled = false;
@@ -111,7 +114,7 @@ public void testFailOnExceptionFromStartUp() {
       service.startAsync().awaitRunning();
       fail();
     } catch (IllegalStateException e) {
-      assertEquals(service.startUpException, e.getCause());
+      assertThat(e).hasCauseThat().isEqualTo(service.startUpException);
     }
     assertEquals(0, service.numberOfTimesRunCalled.get());
     assertEquals(Service.State.FAILED, service.state());
@@ -154,7 +157,7 @@ public void testFailOnExceptionFromShutDown() throws Exception {
       service.awaitTerminated();
       fail();
     } catch (IllegalStateException e) {
-      assertEquals(service.shutDownException, e.getCause());
+      assertThat(e).hasCauseThat().isEqualTo(service.shutDownException);
     }
     assertEquals(Service.State.FAILED, service.state());
   }
@@ -206,7 +209,7 @@ protected ScheduledExecutorService executor() {
 
           @Override
           protected Scheduler scheduler() {
-            return newFixedDelaySchedule(0, 1, TimeUnit.MILLISECONDS);
+            return newFixedDelaySchedule(0, 1, MILLISECONDS);
           }
         };
 
@@ -215,7 +218,7 @@ protected Scheduler scheduler() {
     service.awaitRunning();
     service.stopAsync();
     service.awaitTerminated();
-    assertTrue(executor.get().awaitTermination(100, TimeUnit.MILLISECONDS));
+    assertTrue(executor.get().awaitTermination(100, MILLISECONDS));
   }
 
   public void testDefaultExecutorIsShutdownWhenServiceFails() throws Exception {
@@ -238,7 +241,7 @@ protected ScheduledExecutorService executor() {
 
           @Override
           protected Scheduler scheduler() {
-            return newFixedDelaySchedule(0, 1, TimeUnit.MILLISECONDS);
+            return newFixedDelaySchedule(0, 1, MILLISECONDS);
           }
         };
 
@@ -248,7 +251,7 @@ protected Scheduler scheduler() {
     } catch (IllegalStateException expected) {
     }
 
-    assertTrue(executor.get().awaitTermination(100, TimeUnit.MILLISECONDS));
+    assertTrue(executor.get().awaitTermination(100, MILLISECONDS));
   }
 
   public void testSchedulerOnlyCalledOnce() throws Exception {
@@ -275,7 +278,7 @@ public void testTimeout() {
         new AbstractScheduledService() {
           @Override
           protected Scheduler scheduler() {
-            return Scheduler.newFixedDelaySchedule(0, 1, TimeUnit.NANOSECONDS);
+            return Scheduler.newFixedDelaySchedule(0, 1, NANOSECONDS);
           }
 
           @Override
@@ -292,7 +295,7 @@ protected String serviceName() {
           }
         };
     try {
-      service.startAsync().awaitRunning(1, TimeUnit.MILLISECONDS);
+      service.startAsync().awaitRunning(1, MILLISECONDS);
       fail("Expected timeout");
     } catch (TimeoutException e) {
       assertThat(e)
@@ -364,9 +367,9 @@ protected Scheduler scheduler() {
   public static class SchedulerTest extends TestCase {
     // These constants are arbitrary and just used to make sure that the correct method is called
     // with the correct parameters.
-    private static final int initialDelay = 10;
-    private static final int delay = 20;
-    private static final TimeUnit unit = TimeUnit.MILLISECONDS;
+    private static final int INITIAL_DELAY = 10;
+    private static final int DELAY = 20;
+    private static final TimeUnit UNIT = MILLISECONDS;
 
     // Unique runnable object used for comparison.
     final Runnable testRunnable =
@@ -380,23 +383,23 @@ private void assertSingleCallWithCorrectParameters(
         Runnable command, long initialDelay, long delay, TimeUnit unit) {
       assertFalse(called); // only called once.
       called = true;
-      assertEquals(SchedulerTest.initialDelay, initialDelay);
-      assertEquals(SchedulerTest.delay, delay);
-      assertEquals(SchedulerTest.unit, unit);
+      assertEquals(INITIAL_DELAY, initialDelay);
+      assertEquals(DELAY, delay);
+      assertEquals(UNIT, unit);
       assertEquals(testRunnable, command);
     }
 
     public void testFixedRateSchedule() {
-      Scheduler schedule = Scheduler.newFixedRateSchedule(initialDelay, delay, unit);
-      Future<?> unused =
+      Scheduler schedule = Scheduler.newFixedRateSchedule(INITIAL_DELAY, DELAY, UNIT);
+      Cancellable unused =
           schedule.schedule(
               null,
               new ScheduledThreadPoolExecutor(1) {
                 @Override
                 public ScheduledFuture<?> scheduleAtFixedRate(
                     Runnable command, long initialDelay, long period, TimeUnit unit) {
-                  assertSingleCallWithCorrectParameters(command, initialDelay, delay, unit);
-                  return null;
+                  assertSingleCallWithCorrectParameters(command, initialDelay, period, unit);
+                  return new ThrowingScheduledFuture<>();
                 }
               },
               testRunnable);
@@ -404,8 +407,8 @@ public ScheduledFuture<?> scheduleAtFixedRate(
     }
 
     public void testFixedDelaySchedule() {
-      Scheduler schedule = newFixedDelaySchedule(initialDelay, delay, unit);
-      Future<?> unused =
+      Scheduler schedule = newFixedDelaySchedule(INITIAL_DELAY, DELAY, UNIT);
+      Cancellable unused =
           schedule.schedule(
               null,
               new ScheduledThreadPoolExecutor(10) {
@@ -413,13 +416,30 @@ public void testFixedDelaySchedule() {
                 public ScheduledFuture<?> scheduleWithFixedDelay(
                     Runnable command, long initialDelay, long delay, TimeUnit unit) {
                   assertSingleCallWithCorrectParameters(command, initialDelay, delay, unit);
-                  return null;
+                  return new ThrowingScheduledFuture<>();
                 }
               },
               testRunnable);
       assertTrue(called);
     }
 
+    private static final class ThrowingScheduledFuture<V> extends ForwardingFuture<V>
+        implements ScheduledFuture<V> {
+      @Override
+      protected Future<V> delegate() {
+        throw new UnsupportedOperationException("test should not care about this");
+      }
+
+      @Override
+      public long getDelay(TimeUnit unit) {
+        throw new UnsupportedOperationException("test should not care about this");
+      }
+
+      @Override
+      public int compareTo(Delayed other) {
+        throw new UnsupportedOperationException("test should not care about this");
+      }
+    }
 
     public void testFixedDelayScheduleFarFuturePotentiallyOverflowingScheduleIsNeverReached()
         throws Exception {
@@ -441,7 +461,6 @@ protected Scheduler scheduler() {
       service.awaitTerminated();
     }
 
-
     public void testCustomSchedulerFarFuturePotentiallyOverflowingScheduleIsNeverReached()
         throws Exception {
       TestAbstractScheduledCustomService service =
@@ -467,17 +486,16 @@ protected Schedule getNextSchedule() throws Exception {
       service.awaitTerminated();
     }
 
-    private class TestCustomScheduler extends AbstractScheduledService.CustomScheduler {
+    private static class TestCustomScheduler extends AbstractScheduledService.CustomScheduler {
       public AtomicInteger scheduleCounter = new AtomicInteger(0);
 
       @Override
       protected Schedule getNextSchedule() throws Exception {
         scheduleCounter.incrementAndGet();
-        return new Schedule(0, TimeUnit.SECONDS);
+        return new Schedule(0, SECONDS);
       }
     }
 
-
     public void testCustomSchedule_startStop() throws Exception {
       final CyclicBarrier firstBarrier = new CyclicBarrier(2);
       final CyclicBarrier secondBarrier = new CyclicBarrier(2);
@@ -497,7 +515,7 @@ public void run() {
             }
           };
       TestCustomScheduler scheduler = new TestCustomScheduler();
-      Future<?> future = scheduler.schedule(null, Executors.newScheduledThreadPool(10), task);
+      Cancellable future = scheduler.schedule(null, Executors.newScheduledThreadPool(10), task);
       firstBarrier.await();
       assertEquals(1, scheduler.scheduleCounter.get());
       secondBarrier.await();
@@ -508,7 +526,6 @@ public void run() {
       future.cancel(false);
     }
 
-
     public void testCustomSchedulerServiceStop() throws Exception {
       TestAbstractScheduledCustomService service = new TestAbstractScheduledCustomService();
       service.startAsync().awaitRunning();
@@ -518,11 +535,10 @@ public void testCustomSchedulerServiceStop() throws Exception {
       service.secondBarrier.await();
       service.awaitTerminated();
       // Sleep for a while just to ensure that our task wasn't called again.
-      Thread.sleep(unit.toMillis(3 * delay));
+      Thread.sleep(UNIT.toMillis(3 * DELAY));
       assertEquals(1, service.numIterations.get());
     }
 
-
     public void testCustomScheduler_deadlock() throws InterruptedException, BrokenBarrierException {
       final CyclicBarrier inGetNextSchedule = new CyclicBarrier(2);
       // This will flakily deadlock, so run it multiple times to increase the flake likelihood
@@ -542,7 +558,7 @@ protected Schedule getNextSchedule() throws Exception {
                       Thread.yield();
                       throw new RuntimeException("boom");
                     }
-                    return new Schedule(0, TimeUnit.NANOSECONDS);
+                    return new Schedule(0, NANOSECONDS);
                   }
                 };
               }
@@ -553,7 +569,6 @@ protected Schedule getNextSchedule() throws Exception {
       }
     }
 
-
     public void testBig() throws Exception {
       TestAbstractScheduledCustomService service =
           new TestAbstractScheduledCustomService() {
@@ -564,7 +579,7 @@ protected Scheduler scheduler() {
                 protected Schedule getNextSchedule() throws Exception {
                   // Explicitly yield to increase the probability of a pathological scheduling.
                   Thread.yield();
-                  return new Schedule(0, TimeUnit.SECONDS);
+                  return new Schedule(0, SECONDS);
                 }
               };
             }
@@ -607,13 +622,12 @@ protected Scheduler scheduler() {
         return new CustomScheduler() {
           @Override
           protected Schedule getNextSchedule() throws Exception {
-            return new Schedule(delay, unit);
+            return new Schedule(DELAY, UNIT);
           }
         };
       }
     }
 
-
     public void testCustomSchedulerFailure() throws Exception {
       TestFailingCustomScheduledService service = new TestFailingCustomScheduledService();
       service.startAsync().awaitRunning();
@@ -624,7 +638,7 @@ public void testCustomSchedulerFailure() throws Exception {
       }
       Thread.sleep(1000);
       try {
-        service.stopAsync().awaitTerminated(100, TimeUnit.SECONDS);
+        service.stopAsync().awaitTerminated(100, SECONDS);
         fail();
       } catch (IllegalStateException e) {
         assertEquals(State.FAILED, service.state());
@@ -657,7 +671,7 @@ protected Schedule getNextSchedule() throws Exception {
             if (numIterations.get() > 2) {
               throw new IllegalStateException("Failed");
             }
-            return new Schedule(delay, unit);
+            return new Schedule(DELAY, UNIT);
           }
         };
       }
diff --git a/guava-tests/test/com/google/common/util/concurrent/AbstractServiceTest.java b/guava-tests/test/com/google/common/util/concurrent/AbstractServiceTest.java
index e3c22a8673df..5f4210621ea8 100644
--- a/guava-tests/test/com/google/common/util/concurrent/AbstractServiceTest.java
+++ b/guava-tests/test/com/google/common/util/concurrent/AbstractServiceTest.java
@@ -330,7 +330,6 @@ protected void doStop() {
     }
   }
 
-
   public void testAwaitTerminated() throws Exception {
     final NoOpService service = new NoOpService();
     Thread waiter =
@@ -348,7 +347,6 @@ public void run() {
     assertFalse(waiter.isAlive());
   }
 
-
   public void testAwaitTerminated_FailedService() throws Exception {
     final ManualSwitchedService service = new ManualSwitchedService();
     final AtomicReference<Throwable> exception = Atomics.newReference();
@@ -376,7 +374,6 @@ public void run() {
     assertThat(exception.get()).hasCauseThat().isEqualTo(EXCEPTION);
   }
 
-
   public void testThreadedServiceStartAndWaitStopAndWait() throws Throwable {
     ThreadedService service = new ThreadedService();
     RecordingListener listener = RecordingListener.record(service);
@@ -394,7 +391,6 @@ public void testThreadedServiceStartAndWaitStopAndWait() throws Throwable {
         listener.getStateHistory());
   }
 
-
   public void testThreadedServiceStopIdempotence() throws Throwable {
     ThreadedService service = new ThreadedService();
 
@@ -410,7 +406,6 @@ public void testThreadedServiceStopIdempotence() throws Throwable {
     throwIfSet(thrownByExecutionThread);
   }
 
-
   public void testThreadedServiceStopIdempotenceAfterWait() throws Throwable {
     ThreadedService service = new ThreadedService();
 
@@ -428,7 +423,6 @@ public void testThreadedServiceStopIdempotenceAfterWait() throws Throwable {
     throwIfSet(thrownByExecutionThread);
   }
 
-
   public void testThreadedServiceStopIdempotenceDoubleWait() throws Throwable {
     ThreadedService service = new ThreadedService();
 
@@ -661,7 +655,6 @@ public void testFailureCause_throwsIfNotFailed() {
     }
   }
 
-
   public void testAddListenerAfterFailureDoesntCauseDeadlock() throws InterruptedException {
     final StartFailingService service = new StartFailingService();
     service.startAsync();
@@ -681,7 +674,6 @@ public void run() {
     assertFalse(thread + " is deadlocked", thread.isAlive());
   }
 
-
   public void testListenerDoesntDeadlockOnStartAndWaitFromRunning() throws Exception {
     final NoOpThreadedService service = new NoOpThreadedService();
     service.addListener(
@@ -696,7 +688,6 @@ public void running() {
     service.stopAsync();
   }
 
-
   public void testListenerDoesntDeadlockOnStopAndWaitFromTerminated() throws Exception {
     final NoOpThreadedService service = new NoOpThreadedService();
     service.addListener(
diff --git a/guava-tests/test/com/google/common/util/concurrent/AtomicDoubleArrayTest.java b/guava-tests/test/com/google/common/util/concurrent/AtomicDoubleArrayTest.java
index 038e2ec69bc0..de7d58a9c30f 100644
--- a/guava-tests/test/com/google/common/util/concurrent/AtomicDoubleArrayTest.java
+++ b/guava-tests/test/com/google/common/util/concurrent/AtomicDoubleArrayTest.java
@@ -13,6 +13,10 @@
 
 package com.google.common.util.concurrent;
 
+import static java.lang.Math.max;
+
+import com.google.common.annotations.GwtIncompatible;
+import com.google.common.testing.NullPointerTester;
 import java.util.Arrays;
 
 /** Unit test for {@link AtomicDoubleArray}. */
@@ -48,6 +52,13 @@ static void assertBitEquals(double x, double y) {
     assertEquals(Double.doubleToRawLongBits(x), Double.doubleToRawLongBits(y));
   }
 
+  @GwtIncompatible // NullPointerTester
+  public void testNulls() {
+    new NullPointerTester().testAllPublicStaticMethods(AtomicDoubleArray.class);
+    new NullPointerTester().testAllPublicConstructors(AtomicDoubleArray.class);
+    new NullPointerTester().testAllPublicInstanceMethods(new AtomicDoubleArray(1));
+  }
+
   /** constructor creates array of given size with all elements zero */
   public void testConstructor() {
     AtomicDoubleArray aa = new AtomicDoubleArray(SIZE);
@@ -181,7 +192,6 @@ public void testCompareAndSet() {
   }
 
   /** compareAndSet in one thread enables another waiting for value to succeed */
-
   public void testCompareAndSetInMultipleThreads() throws InterruptedException {
     final AtomicDoubleArray a = new AtomicDoubleArray(1);
     a.set(0, 1.0);
@@ -211,7 +221,8 @@ public void testWeakCompareAndSet() {
         assertBitEquals(prev, aa.get(i));
         assertFalse(aa.weakCompareAndSet(i, unused, x));
         assertBitEquals(prev, aa.get(i));
-        while (!aa.weakCompareAndSet(i, prev, x)) {;
+        while (!aa.weakCompareAndSet(i, prev, x)) {
+          ;
         }
         assertBitEquals(x, aa.get(i));
         prev = x;
@@ -261,6 +272,128 @@ public void testAddAndGet() {
     }
   }
 
+  /** getAndAccumulate with sum adds given value to current, and returns previous value */
+  public void testGetAndAccumulateWithSum() {
+    AtomicDoubleArray aa = new AtomicDoubleArray(SIZE);
+    for (int i : new int[] {0, SIZE - 1}) {
+      for (double x : VALUES) {
+        for (double y : VALUES) {
+          aa.set(i, x);
+          double z = aa.getAndAccumulate(i, y, Double::sum);
+          assertBitEquals(x, z);
+          assertBitEquals(x + y, aa.get(i));
+        }
+      }
+    }
+  }
+
+  /** getAndAccumulate with max stores max of given value to current, and returns previous value */
+  public void testGetAndAccumulateWithMax() {
+    AtomicDoubleArray aa = new AtomicDoubleArray(SIZE);
+    for (int i : new int[] {0, SIZE - 1}) {
+      for (double x : VALUES) {
+        for (double y : VALUES) {
+          aa.set(i, x);
+          double z = aa.getAndAccumulate(i, y, Double::max);
+          double expectedMax = max(x, y);
+          assertBitEquals(x, z);
+          assertBitEquals(expectedMax, aa.get(i));
+        }
+      }
+    }
+  }
+
+  /** accumulateAndGet with sum adds given value to current, and returns current value */
+  public void testAccumulateAndGetWithSum() {
+    AtomicDoubleArray aa = new AtomicDoubleArray(SIZE);
+    for (int i : new int[] {0, SIZE - 1}) {
+      for (double x : VALUES) {
+        for (double y : VALUES) {
+          aa.set(i, x);
+          double z = aa.accumulateAndGet(i, y, Double::sum);
+          assertBitEquals(x + y, z);
+          assertBitEquals(x + y, aa.get(i));
+        }
+      }
+    }
+  }
+
+  /** accumulateAndGet with max stores max of given value to current, and returns current value */
+  public void testAccumulateAndGetWithMax() {
+    AtomicDoubleArray aa = new AtomicDoubleArray(SIZE);
+    for (int i : new int[] {0, SIZE - 1}) {
+      for (double x : VALUES) {
+        for (double y : VALUES) {
+          aa.set(i, x);
+          double z = aa.accumulateAndGet(i, y, Double::max);
+          double expectedMax = max(x, y);
+          assertBitEquals(expectedMax, z);
+          assertBitEquals(expectedMax, aa.get(i));
+        }
+      }
+    }
+  }
+
+  /** getAndUpdate adds given value to current, and returns previous value */
+  public void testGetAndUpdateWithSum() {
+    AtomicDoubleArray aa = new AtomicDoubleArray(SIZE);
+    for (int i : new int[] {0, SIZE - 1}) {
+      for (double x : VALUES) {
+        for (double y : VALUES) {
+          aa.set(i, x);
+          double z = aa.getAndUpdate(i, value -> value + y);
+          assertBitEquals(x, z);
+          assertBitEquals(x + y, aa.get(i));
+        }
+      }
+    }
+  }
+
+  /** getAndUpdate subtracts given value to current, and returns previous value */
+  public void testGetAndUpdateWithSubtract() {
+    AtomicDoubleArray aa = new AtomicDoubleArray(SIZE);
+    for (int i : new int[] {0, SIZE - 1}) {
+      for (double x : VALUES) {
+        for (double y : VALUES) {
+          aa.set(i, x);
+          double z = aa.getAndUpdate(i, value -> value - y);
+          assertBitEquals(x, z);
+          assertBitEquals(x - y, aa.get(i));
+        }
+      }
+    }
+  }
+
+  /** updateAndGet adds given value to current, and returns current value */
+  public void testUpdateAndGetWithSum() {
+    AtomicDoubleArray aa = new AtomicDoubleArray(SIZE);
+    for (int i : new int[] {0, SIZE - 1}) {
+      for (double x : VALUES) {
+        for (double y : VALUES) {
+          aa.set(i, x);
+          double z = aa.updateAndGet(i, value -> value + y);
+          assertBitEquals(x + y, z);
+          assertBitEquals(x + y, aa.get(i));
+        }
+      }
+    }
+  }
+
+  /** updateAndGet subtracts given value to current, and returns current value */
+  public void testUpdateAndGetWithSubtract() {
+    AtomicDoubleArray aa = new AtomicDoubleArray(SIZE);
+    for (int i : new int[] {0, SIZE - 1}) {
+      for (double x : VALUES) {
+        for (double y : VALUES) {
+          aa.set(i, x);
+          double z = aa.updateAndGet(i, value -> value - y);
+          assertBitEquals(x - y, z);
+          assertBitEquals(x - y, aa.get(i));
+        }
+      }
+    }
+  }
+
   static final long COUNTDOWN = 100000;
 
   class Counter extends CheckedRunnable {
@@ -296,7 +429,6 @@ public void realRun() {
    * Multiple threads using same array of counters successfully update a number of times equal to
    * total count
    */
-
   public void testCountingInMultipleThreads() throws InterruptedException {
     final AtomicDoubleArray aa = new AtomicDoubleArray(SIZE);
     for (int i = 0; i < SIZE; i++) {
diff --git a/guava-tests/test/com/google/common/util/concurrent/AtomicDoubleTest.java b/guava-tests/test/com/google/common/util/concurrent/AtomicDoubleTest.java
index df9bd8bd73a6..f7ffe51b9fed 100644
--- a/guava-tests/test/com/google/common/util/concurrent/AtomicDoubleTest.java
+++ b/guava-tests/test/com/google/common/util/concurrent/AtomicDoubleTest.java
@@ -13,6 +13,7 @@
 
 package com.google.common.util.concurrent;
 
+import static java.lang.Math.max;
 
 /** Unit test for {@link AtomicDouble}. */
 public class AtomicDoubleTest extends JSR166TestCase {
@@ -97,7 +98,6 @@ public void testCompareAndSet() {
   }
 
   /** compareAndSet in one thread enables another waiting for value to succeed */
-
   public void testCompareAndSetInMultipleThreads() throws Exception {
     final AtomicDouble at = new AtomicDouble(1.0);
     Thread t =
@@ -125,7 +125,8 @@ public void testWeakCompareAndSet() {
       assertBitEquals(prev, at.get());
       assertFalse(at.weakCompareAndSet(unused, x));
       assertBitEquals(prev, at.get());
-      while (!at.weakCompareAndSet(prev, x)) {;
+      while (!at.weakCompareAndSet(prev, x)) {
+        ;
       }
       assertBitEquals(x, at.get());
       prev = x;
@@ -166,6 +167,108 @@ public void testAddAndGet() {
     }
   }
 
+  /** getAndAccumulate with sum adds given value to current, and returns previous value */
+  public void testGetAndAccumulateWithSum() {
+    for (double x : VALUES) {
+      for (double y : VALUES) {
+        AtomicDouble a = new AtomicDouble(x);
+        double z = a.getAndAccumulate(y, Double::sum);
+        assertBitEquals(x, z);
+        assertBitEquals(x + y, a.get());
+      }
+    }
+  }
+
+  /** getAndAccumulate with max stores max of given value to current, and returns previous value */
+  public void testGetAndAccumulateWithMax() {
+    for (double x : VALUES) {
+      for (double y : VALUES) {
+        AtomicDouble a = new AtomicDouble(x);
+        double z = a.getAndAccumulate(y, Double::max);
+        double expectedMax = max(x, y);
+        assertBitEquals(x, z);
+        assertBitEquals(expectedMax, a.get());
+      }
+    }
+  }
+
+  /** accumulateAndGet with sum adds given value to current, and returns current value */
+  public void testAccumulateAndGetWithSum() {
+    for (double x : VALUES) {
+      for (double y : VALUES) {
+        AtomicDouble a = new AtomicDouble(x);
+        double z = a.accumulateAndGet(y, Double::sum);
+        assertBitEquals(x + y, z);
+        assertBitEquals(x + y, a.get());
+      }
+    }
+  }
+
+  /** accumulateAndGet with max stores max of given value to current, and returns current value */
+  public void testAccumulateAndGetWithMax() {
+    for (double x : VALUES) {
+      for (double y : VALUES) {
+        AtomicDouble a = new AtomicDouble(x);
+        double z = a.accumulateAndGet(y, Double::max);
+        double expectedMax = max(x, y);
+        assertBitEquals(expectedMax, z);
+        assertBitEquals(expectedMax, a.get());
+      }
+    }
+  }
+
+  /** getAndUpdate with sum stores sum of given value to current, and returns previous value */
+  public void testGetAndUpdateWithSum() {
+    for (double x : VALUES) {
+      for (double y : VALUES) {
+        AtomicDouble a = new AtomicDouble(x);
+        double z = a.getAndUpdate(value -> value + y);
+        assertBitEquals(x, z);
+        assertBitEquals(x + y, a.get());
+      }
+    }
+  }
+
+  /**
+   * getAndUpdate with subtract stores subtraction of value from current, and returns previous value
+   */
+  public void testGetAndUpdateWithSubtract() {
+    for (double x : VALUES) {
+      for (double y : VALUES) {
+        AtomicDouble a = new AtomicDouble(x);
+        double z = a.getAndUpdate(value -> value - y);
+        assertBitEquals(x, z);
+        assertBitEquals(x - y, a.get());
+      }
+    }
+  }
+
+  /** updateAndGet with sum stores sum of given value to current, and returns current value */
+  public void testUpdateAndGetWithSum() {
+    for (double x : VALUES) {
+      for (double y : VALUES) {
+        AtomicDouble a = new AtomicDouble(x);
+        double z = a.updateAndGet(value -> value + y);
+        assertBitEquals(x + y, z);
+        assertBitEquals(x + y, a.get());
+      }
+    }
+  }
+
+  /**
+   * updateAndGet with subtract stores subtraction of value from current, and returns current value
+   */
+  public void testUpdateAndGetWithSubtract() {
+    for (double x : VALUES) {
+      for (double y : VALUES) {
+        AtomicDouble a = new AtomicDouble(x);
+        double z = a.updateAndGet(value -> value - y);
+        assertBitEquals(x - y, z);
+        assertBitEquals(x - y, a.get());
+      }
+    }
+  }
+
   /** a deserialized serialized atomic holds same value */
   public void testSerialization() throws Exception {
     AtomicDouble a = new AtomicDouble();
diff --git a/guava-tests/test/com/google/common/util/concurrent/AtomicLongMapBasherTest.java b/guava-tests/test/com/google/common/util/concurrent/AtomicLongMapBasherTest.java
index 4765825855ba..b1e741a68118 100644
--- a/guava-tests/test/com/google/common/util/concurrent/AtomicLongMapBasherTest.java
+++ b/guava-tests/test/com/google/common/util/concurrent/AtomicLongMapBasherTest.java
@@ -16,13 +16,15 @@
 
 package com.google.common.util.concurrent;
 
+import static java.util.concurrent.TimeUnit.SECONDS;
+
 import com.google.common.annotations.GwtIncompatible;
+import java.util.ArrayList;
 import java.util.Random;
+import java.util.concurrent.Callable;
 import java.util.concurrent.ExecutorService;
 import java.util.concurrent.Executors;
 import java.util.concurrent.Future;
-import java.util.concurrent.TimeUnit;
-import java.util.concurrent.atomic.AtomicLong;
 import junit.framework.TestCase;
 
 /**
@@ -31,29 +33,27 @@
  * @author mike nonemacher
  */
 @GwtIncompatible // threads
-
 public class AtomicLongMapBasherTest extends TestCase {
   private final Random random = new Random(301);
 
-  public void testModify_basher() throws InterruptedException {
+  public void testModify_basher() throws Exception {
     int nTasks = 3000;
     int nThreads = 100;
     final int getsPerTask = 1000;
     final int deltaRange = 10000;
     final String key = "key";
 
-    final AtomicLong sum = new AtomicLong();
     final AtomicLongMap<String> map = AtomicLongMap.create();
 
     ExecutorService threadPool = Executors.newFixedThreadPool(nThreads);
+    ArrayList<Future<Long>> futures = new ArrayList<>();
     for (int i = 0; i < nTasks; i++) {
-      @SuppressWarnings("unused") // https://errorprone.info/bugpattern/FutureReturnValueIgnored
-      Future<?> possiblyIgnoredError =
+      futures.add(
           threadPool.submit(
-              new Runnable() {
+              new Callable<Long>() {
                 @Override
-                public void run() {
-                  int threadSum = 0;
+                public Long call() {
+                  long threadSum = 0;
                   for (int j = 0; j < getsPerTask; j++) {
                     long delta = random.nextInt(deltaRange);
                     int behavior = random.nextInt(10);
@@ -106,14 +106,16 @@ public void run() {
                         throw new AssertionError();
                     }
                   }
-                  sum.addAndGet(threadSum);
+                  return threadSum;
                 }
-              });
+              }));
     }
-
     threadPool.shutdown();
-    assertTrue(threadPool.awaitTermination(300, TimeUnit.SECONDS));
-
-    assertEquals(sum.get(), map.get(key));
+    assertTrue(threadPool.awaitTermination(300, SECONDS));
+    long sum = 0;
+    for (Future<Long> f : futures) {
+      sum += f.get();
+    }
+    assertEquals(sum, map.get(key));
   }
 }
diff --git a/guava-tests/test/com/google/common/util/concurrent/AtomicLongMapTest.java b/guava-tests/test/com/google/common/util/concurrent/AtomicLongMapTest.java
index 587a4ec21d72..878ea5ec87ac 100644
--- a/guava-tests/test/com/google/common/util/concurrent/AtomicLongMapTest.java
+++ b/guava-tests/test/com/google/common/util/concurrent/AtomicLongMapTest.java
@@ -52,7 +52,7 @@ public void testCreate_map() {
     Map<String, Long> in = ImmutableMap.of("1", 1L, "2", 2L, "3", 3L);
     AtomicLongMap<String> map = AtomicLongMap.create(in);
     assertFalse(map.isEmpty());
-    assertSame(3, map.size());
+    assertEquals(3, map.size());
     assertTrue(map.containsKey("1"));
     assertTrue(map.containsKey("2"));
     assertTrue(map.containsKey("3"));
@@ -302,7 +302,7 @@ public void testPutAll() {
     Map<String, Long> in = ImmutableMap.of("1", 1L, "2", 2L, "3", 3L);
     AtomicLongMap<String> map = AtomicLongMap.create();
     assertTrue(map.isEmpty());
-    assertSame(0, map.size());
+    assertEquals(0, map.size());
     assertFalse(map.containsKey("1"));
     assertFalse(map.containsKey("2"));
     assertFalse(map.containsKey("3"));
@@ -312,7 +312,7 @@ public void testPutAll() {
 
     map.putAll(in);
     assertFalse(map.isEmpty());
-    assertSame(3, map.size());
+    assertEquals(3, map.size());
     assertTrue(map.containsKey("1"));
     assertTrue(map.containsKey("2"));
     assertTrue(map.containsKey("3"));
diff --git a/guava-tests/test/com/google/common/util/concurrent/ClosingFutureFinishToFutureTest.java b/guava-tests/test/com/google/common/util/concurrent/ClosingFutureFinishToFutureTest.java
new file mode 100644
index 000000000000..79288eb2a0a9
--- /dev/null
+++ b/guava-tests/test/com/google/common/util/concurrent/ClosingFutureFinishToFutureTest.java
@@ -0,0 +1,94 @@
+/*
+ * Copyright (C) 2017 The Guava Authors
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package com.google.common.util.concurrent;
+
+import static com.google.common.truth.Truth.assertThat;
+import static com.google.common.util.concurrent.Futures.immediateFuture;
+import static com.google.common.util.concurrent.MoreExecutors.directExecutor;
+import static com.google.common.util.concurrent.Uninterruptibles.getUninterruptibly;
+
+import com.google.common.util.concurrent.ClosingFuture.ClosingCallable;
+import com.google.common.util.concurrent.ClosingFuture.DeferredCloser;
+import java.io.Closeable;
+import java.util.concurrent.ExecutionException;
+
+/** Tests for {@link ClosingFuture} that exercise {@link ClosingFuture#finishToFuture()}. */
+public class ClosingFutureFinishToFutureTest extends AbstractClosingFutureTest {
+  public void testFinishToFuture_throwsIfCalledTwice() throws Exception {
+    ClosingFuture<Closeable> closingFuture =
+        ClosingFuture.submit(
+            new ClosingCallable<Closeable>() {
+              @Override
+              public Closeable call(DeferredCloser closer) throws Exception {
+                return closer.eventuallyClose(mockCloseable, executor);
+              }
+            },
+            executor);
+    FluentFuture<Closeable> unused = closingFuture.finishToFuture();
+    try {
+      FluentFuture<Closeable> unused2 = closingFuture.finishToFuture();
+      fail("should have thrown");
+    } catch (IllegalStateException expected) {
+    }
+  }
+
+  public void testFinishToFuture_throwsAfterCallingFinishToValueAndCloser() throws Exception {
+    ClosingFuture<Closeable> closingFuture =
+        ClosingFuture.submit(
+            new ClosingCallable<Closeable>() {
+              @Override
+              public Closeable call(DeferredCloser closer) throws Exception {
+                return closer.eventuallyClose(mockCloseable, executor);
+              }
+            },
+            executor);
+    closingFuture.finishToValueAndCloser(new NoOpValueAndCloserConsumer<>(), directExecutor());
+    try {
+      FluentFuture<Closeable> unused = closingFuture.finishToFuture();
+      fail("should have thrown");
+    } catch (IllegalStateException expected) {
+    }
+  }
+
+  public void testFinishToFuture_preventsFurtherDerivation() {
+    ClosingFuture<String> closingFuture = ClosingFuture.from(immediateFuture("value1"));
+    FluentFuture<String> unused = closingFuture.finishToFuture();
+    assertDerivingThrowsIllegalStateException(closingFuture);
+  }
+
+  @Override
+  <T> T getFinalValue(ClosingFuture<T> closingFuture) throws ExecutionException {
+    return getUninterruptibly(closingFuture.finishToFuture());
+  }
+
+  @Override
+  void assertFinallyFailsWithException(ClosingFuture<?> closingFuture) {
+    assertThatFutureFailsWithException(closingFuture.finishToFuture());
+  }
+
+  @Override
+  void assertBecomesCanceled(ClosingFuture<?> closingFuture) throws ExecutionException {
+    assertThatFutureBecomesCancelled(closingFuture.finishToFuture());
+  }
+
+  @Override
+  void cancelFinalStepAndWait(ClosingFuture<TestCloseable> closingFuture) {
+    assertThat(closingFuture.finishToFuture().cancel(false)).isTrue();
+    waitUntilClosed(closingFuture);
+    futureCancelled.countDown();
+  }
+}
diff --git a/guava-tests/test/com/google/common/util/concurrent/ClosingFutureFinishToValueAndCloserTest.java b/guava-tests/test/com/google/common/util/concurrent/ClosingFutureFinishToValueAndCloserTest.java
new file mode 100644
index 000000000000..ac3cf556925f
--- /dev/null
+++ b/guava-tests/test/com/google/common/util/concurrent/ClosingFutureFinishToValueAndCloserTest.java
@@ -0,0 +1,148 @@
+/*
+ * Copyright (C) 2017 The Guava Authors
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package com.google.common.util.concurrent;
+
+import static com.google.common.truth.Truth.assertThat;
+import static com.google.common.truth.Truth.assertWithMessage;
+import static com.google.common.util.concurrent.MoreExecutors.shutdownAndAwaitTermination;
+import static com.google.common.util.concurrent.Uninterruptibles.awaitUninterruptibly;
+import static java.util.concurrent.Executors.newSingleThreadExecutor;
+import static java.util.concurrent.TimeUnit.SECONDS;
+
+import com.google.common.util.concurrent.ClosingFuture.ClosingCallable;
+import com.google.common.util.concurrent.ClosingFuture.DeferredCloser;
+import com.google.common.util.concurrent.ClosingFuture.ValueAndCloser;
+import com.google.common.util.concurrent.ClosingFuture.ValueAndCloserConsumer;
+import java.io.Closeable;
+import java.util.concurrent.CountDownLatch;
+import java.util.concurrent.ExecutionException;
+import java.util.concurrent.Executor;
+import java.util.concurrent.ExecutorService;
+
+/**
+ * Tests for {@link ClosingFuture} that exercise {@link
+ * ClosingFuture#finishToValueAndCloser(ValueAndCloserConsumer, Executor)}.
+ */
+public class ClosingFutureFinishToValueAndCloserTest extends AbstractClosingFutureTest {
+  private final ExecutorService finishToValueAndCloserExecutor = newSingleThreadExecutor();
+  private volatile ValueAndCloser<?> valueAndCloser;
+
+  @Override
+  protected void tearDown() throws Exception {
+    super.tearDown();
+    assertWithMessage("finishToValueAndCloserExecutor was shut down")
+        .that(shutdownAndAwaitTermination(finishToValueAndCloserExecutor, 10, SECONDS))
+        .isTrue();
+  }
+
+  public void testFinishToValueAndCloser_throwsIfCalledTwice() throws Exception {
+    ClosingFuture<Closeable> closingFuture =
+        ClosingFuture.submit(
+            new ClosingCallable<Closeable>() {
+              @Override
+              public Closeable call(DeferredCloser closer) throws Exception {
+                return closer.eventuallyClose(mockCloseable, executor);
+              }
+            },
+            executor);
+    closingFuture.finishToValueAndCloser(
+        new NoOpValueAndCloserConsumer<>(), finishToValueAndCloserExecutor);
+    try {
+      closingFuture.finishToValueAndCloser(
+          new NoOpValueAndCloserConsumer<>(), finishToValueAndCloserExecutor);
+      fail("should have thrown");
+    } catch (IllegalStateException expected) {
+    }
+  }
+
+  public void testFinishToValueAndCloser_throwsAfterCallingFinishToFuture() throws Exception {
+    ClosingFuture<Closeable> closingFuture =
+        ClosingFuture.submit(
+            new ClosingCallable<Closeable>() {
+              @Override
+              public Closeable call(DeferredCloser closer) throws Exception {
+                return closer.eventuallyClose(mockCloseable, executor);
+              }
+            },
+            executor);
+    FluentFuture<Closeable> unused = closingFuture.finishToFuture();
+    try {
+      closingFuture.finishToValueAndCloser(
+          new NoOpValueAndCloserConsumer<>(), finishToValueAndCloserExecutor);
+      fail("should have thrown");
+    } catch (IllegalStateException expected) {
+    }
+  }
+
+  @Override
+  <T> T getFinalValue(ClosingFuture<T> closingFuture) throws ExecutionException {
+    return finishToValueAndCloser(closingFuture).get();
+  }
+
+  @Override
+  void assertFinallyFailsWithException(ClosingFuture<?> closingFuture) {
+    assertThatFutureFailsWithException(closingFuture.statusFuture());
+    ValueAndCloser<?> valueAndCloser = finishToValueAndCloser(closingFuture);
+    try {
+      valueAndCloser.get();
+      fail();
+    } catch (ExecutionException expected) {
+      assertThat(expected).hasCauseThat().isSameInstanceAs(exception);
+    }
+    valueAndCloser.closeAsync();
+  }
+
+  @Override
+  void assertBecomesCanceled(ClosingFuture<?> closingFuture) throws ExecutionException {
+    assertThatFutureBecomesCancelled(closingFuture.statusFuture());
+  }
+
+  @Override
+  void waitUntilClosed(ClosingFuture<?> closingFuture) {
+    if (valueAndCloser != null) {
+      valueAndCloser.closeAsync();
+    }
+    super.waitUntilClosed(closingFuture);
+  }
+
+  @Override
+  void cancelFinalStepAndWait(ClosingFuture<TestCloseable> closingFuture) {
+    assertThat(closingFuture.cancel(false)).isTrue();
+    ValueAndCloser<?> unused = finishToValueAndCloser(closingFuture);
+    waitUntilClosed(closingFuture);
+    futureCancelled.countDown();
+  }
+
+  private <V> ValueAndCloser<V> finishToValueAndCloser(ClosingFuture<V> closingFuture) {
+    final CountDownLatch valueAndCloserSet = new CountDownLatch(1);
+    closingFuture.finishToValueAndCloser(
+        new ValueAndCloserConsumer<V>() {
+          @Override
+          public void accept(ValueAndCloser<V> valueAndCloser) {
+            ClosingFutureFinishToValueAndCloserTest.this.valueAndCloser = valueAndCloser;
+            valueAndCloserSet.countDown();
+          }
+        },
+        finishToValueAndCloserExecutor);
+    assertWithMessage("valueAndCloser was set")
+        .that(awaitUninterruptibly(valueAndCloserSet, 10, SECONDS))
+        .isTrue();
+    @SuppressWarnings("unchecked")
+    ValueAndCloser<V> valueAndCloserWithType = (ValueAndCloser<V>) valueAndCloser;
+    return valueAndCloserWithType;
+  }
+}
diff --git a/guava-tests/test/com/google/common/util/concurrent/CycleDetectingLockFactoryTest.java b/guava-tests/test/com/google/common/util/concurrent/CycleDetectingLockFactoryTest.java
index 18e69b10ee39..2b1dd2fa0881 100644
--- a/guava-tests/test/com/google/common/util/concurrent/CycleDetectingLockFactoryTest.java
+++ b/guava-tests/test/com/google/common/util/concurrent/CycleDetectingLockFactoryTest.java
@@ -442,7 +442,6 @@ public void testDifferentLockFactories_policyExecution() {
     lockD.lock();
   }
 
-
   public void testReentrantLock_tryLock() throws Exception {
     LockingThread thread = new LockingThread(lockA);
     thread.start();
@@ -454,7 +453,6 @@ public void testReentrantLock_tryLock() throws Exception {
     assertTrue(lockA.tryLock());
   }
 
-
   public void testReentrantWriteLock_tryLock() throws Exception {
     LockingThread thread = new LockingThread(writeLockA);
     thread.start();
@@ -468,7 +466,6 @@ public void testReentrantWriteLock_tryLock() throws Exception {
     assertTrue(readLockA.tryLock());
   }
 
-
   public void testReentrantReadLock_tryLock() throws Exception {
     LockingThread thread = new LockingThread(readLockA);
     thread.start();
diff --git a/guava-tests/test/com/google/common/util/concurrent/ExecutionListTest.java b/guava-tests/test/com/google/common/util/concurrent/ExecutionListTest.java
index 5bd3cf7f44da..34678ed256b8 100644
--- a/guava-tests/test/com/google/common/util/concurrent/ExecutionListTest.java
+++ b/guava-tests/test/com/google/common/util/concurrent/ExecutionListTest.java
@@ -36,7 +36,6 @@ public class ExecutionListTest extends TestCase {
 
   private final ExecutionList list = new ExecutionList();
 
-
   public void testRunOnPopulatedList() throws Exception {
     Executor exec = Executors.newCachedThreadPool();
     CountDownLatch countDownLatch = new CountDownLatch(3);
@@ -67,7 +66,6 @@ public void run() {
     assertEquals(1, runCalled.get());
   }
 
-
   public void testExecute_idempotentConcurrently() throws InterruptedException {
     final CountDownLatch okayToRun = new CountDownLatch(1);
     final AtomicInteger runCalled = new AtomicInteger();
@@ -103,7 +101,6 @@ public void run() {
     assertEquals(1, runCalled.get());
   }
 
-
   public void testAddAfterRun() throws Exception {
     // Run the previous test
     testRunOnPopulatedList();
diff --git a/guava-tests/test/com/google/common/util/concurrent/ExecutionSequencerTest.java b/guava-tests/test/com/google/common/util/concurrent/ExecutionSequencerTest.java
index 1c03f5ac4e57..068287c1986b 100644
--- a/guava-tests/test/com/google/common/util/concurrent/ExecutionSequencerTest.java
+++ b/guava-tests/test/com/google/common/util/concurrent/ExecutionSequencerTest.java
@@ -88,7 +88,6 @@ public void testCancellationDoesNotViolateSerialization() {
     assertThat(thirdCallable.called).isTrue();
   }
 
-
   public void testCancellationMultipleThreads() throws Exception {
     final BlockingCallable blockingCallable = new BlockingCallable();
     ListenableFuture<Void> unused = serializer.submit(blockingCallable, executor);
@@ -116,7 +115,6 @@ public Boolean call() {
     assertThat(getDone(future2)).isFalse();
   }
 
-
   public void testSecondTaskWaitsForFirstEvenIfCancelled() throws Exception {
     final BlockingCallable blockingCallable = new BlockingCallable();
     ListenableFuture<Void> future1 = serializer.submit(blockingCallable, executor);
@@ -327,7 +325,6 @@ private static final class LongHolder {
   private static final int DIRECT_EXECUTIONS_PER_THREAD = 100;
 
   @GwtIncompatible // threads
-
   public void testAvoidsStackOverflow_multipleThreads() throws Exception {
     final LongHolder holder = new LongHolder();
     final ArrayList<ListenableFuture<Integer>> lengthChecks = new ArrayList<>();
diff --git a/guava-tests/test/com/google/common/util/concurrent/FluentFutureTest.java b/guava-tests/test/com/google/common/util/concurrent/FluentFutureTest.java
index cc4751d0f217..ab53f538307e 100644
--- a/guava-tests/test/com/google/common/util/concurrent/FluentFutureTest.java
+++ b/guava-tests/test/com/google/common/util/concurrent/FluentFutureTest.java
@@ -132,7 +132,6 @@ public ListenableFuture<Integer> apply(Integer input) {
     assertThat(f.get()).isEqualTo(2);
   }
 
-
   @GwtIncompatible // withTimeout
   public void testWithTimeout() throws Exception {
     ScheduledExecutorService executor = newScheduledThreadPool(1);
diff --git a/guava-tests/test/com/google/common/util/concurrent/ForwardingObjectTester.java b/guava-tests/test/com/google/common/util/concurrent/ForwardingObjectTester.java
index 021d96de7436..84b0426a6830 100644
--- a/guava-tests/test/com/google/common/util/concurrent/ForwardingObjectTester.java
+++ b/guava-tests/test/com/google/common/util/concurrent/ForwardingObjectTester.java
@@ -61,7 +61,7 @@ static <T extends ForwardingObject> void testForwardingObject(final Class<T> for
             new Function<Object, T>() {
               @Override
               public T apply(Object delegate) {
-                T mock = mock(forwarderClass, CALLS_REAL_METHODS.get());
+                T mock = mock(forwarderClass, CALLS_REAL_METHODS);
                 try {
                   T stubber = doReturn(delegate).when(mock);
                   DELEGATE_METHOD.invoke(stubber);
diff --git a/guava-tests/test/com/google/common/util/concurrent/FuturesGetCheckedTest.java b/guava-tests/test/com/google/common/util/concurrent/FuturesGetCheckedTest.java
index 72b5a46564b6..666a1892982f 100644
--- a/guava-tests/test/com/google/common/util/concurrent/FuturesGetCheckedTest.java
+++ b/guava-tests/test/com/google/common/util/concurrent/FuturesGetCheckedTest.java
@@ -353,7 +353,7 @@ public void testGetCheckedUntimed_exceptionClassUsedInitCause() {
 
   public static final class WillBeUnloadedException extends Exception {}
 
-
+  @AndroidIncompatible // "Parent ClassLoader may not be null"; maybe avoidable if we try?
   public void testGetChecked_classUnloading() throws Exception {
     WeakReference<?> classUsedByGetChecked = doTestClassUnloading();
     GcFinalization.awaitClear(classUsedByGetChecked);
@@ -381,5 +381,8 @@ private WeakReference<?> doTestClassUnloading() throws Exception {
    * environment that forces Futures.getChecked to its fallback WeakSetValidator. One awful way of
    * doing so would be to derive a separate test library by using remove_from_jar to strip out
    * ClassValueValidator.
+   *
+   * Fortunately, we get pretty good coverage "by accident": We run all these tests against the
+   * *backport*, where ClassValueValidator is not present.
    */
 }
diff --git a/guava-tests/test/com/google/common/util/concurrent/FuturesTest.java b/guava-tests/test/com/google/common/util/concurrent/FuturesTest.java
index 0c3a9ae6506e..3fe2347a8797 100644
--- a/guava-tests/test/com/google/common/util/concurrent/FuturesTest.java
+++ b/guava-tests/test/com/google/common/util/concurrent/FuturesTest.java
@@ -53,6 +53,7 @@
 import static java.util.concurrent.Executors.newSingleThreadExecutor;
 import static java.util.concurrent.Executors.newSingleThreadScheduledExecutor;
 import static java.util.concurrent.TimeUnit.MILLISECONDS;
+import static java.util.concurrent.TimeUnit.NANOSECONDS;
 import static java.util.concurrent.TimeUnit.SECONDS;
 
 import com.google.common.annotations.GwtCompatible;
@@ -410,7 +411,6 @@ public ListenableFuture<Bar> apply(Foo unused) {
   }
 
   @GwtIncompatible // threads
-
   public void testTransformAsync_interruptPropagatesToTransformingThread() throws Exception {
     SettableFuture<String> input = SettableFuture.create();
     final CountDownLatch inFunction = new CountDownLatch(1);
@@ -803,7 +803,6 @@ public void testTransform_Executor() throws Exception {
   }
 
   @GwtIncompatible // Threads
-
   public void testTransformAsync_functionToString() throws Exception {
     final CountDownLatch functionCalled = new CountDownLatch(1);
     final CountDownLatch functionBlocking = new CountDownLatch(1);
@@ -1132,7 +1131,6 @@ public ListenableFuture<Integer> apply(Throwable t) {
   }
 
   @GwtIncompatible // threads
-
   public void testCatchingAsync_interruptPropagatesToTransformingThread() throws Exception {
     SettableFuture<String> input = SettableFuture.create();
     final CountDownLatch inFunction = new CountDownLatch(1);
@@ -1172,7 +1170,6 @@ public ListenableFuture<String> apply(Throwable t) throws Exception {
   }
 
   @GwtIncompatible // Threads
-
   public void testCatchingAsync_functionToString() throws Exception {
     final CountDownLatch functionCalled = new CountDownLatch(1);
     final CountDownLatch functionBlocking = new CountDownLatch(1);
@@ -1749,7 +1746,6 @@ public void testTransformAsync_asyncFunction_nullInsteadOfFuture() throws Except
   }
 
   @GwtIncompatible // threads
-
   public void testTransformAsync_asyncFunction_cancelledWhileApplyingFunction()
       throws InterruptedException, ExecutionException {
     final CountDownLatch inFunction = new CountDownLatch(1);
@@ -1784,7 +1780,6 @@ public ListenableFuture<Integer> apply(String input) throws Exception {
   }
 
   @GwtIncompatible // threads
-
   public void testTransformAsync_asyncFunction_cancelledBeforeApplyingFunction()
       throws InterruptedException {
     final AtomicBoolean functionCalled = new AtomicBoolean();
@@ -1858,7 +1853,6 @@ public void testSubmitAsync_asyncCallable_nullInsteadOfFuture() throws Exception
   }
 
   @GwtIncompatible // threads
-
   public void testSubmitAsync_asyncCallable_cancelledWhileApplyingFunction()
       throws InterruptedException, ExecutionException {
     final CountDownLatch inFunction = new CountDownLatch(1);
@@ -1892,7 +1886,6 @@ public ListenableFuture<Integer> call() throws InterruptedException {
   }
 
   @GwtIncompatible // threads
-
   public void testSubmitAsync_asyncCallable_cancelledBeforeApplyingFunction()
       throws InterruptedException {
     final AtomicBoolean callableCalled = new AtomicBoolean();
@@ -1926,7 +1919,6 @@ public void run() {
   }
 
   @GwtIncompatible // threads
-
   public void testSubmitAsync_asyncCallable_returnsInterruptedFuture() throws InterruptedException {
     assertThat(Thread.interrupted()).isFalse();
     SettableFuture<Integer> cancelledFuture = SettableFuture.create();
@@ -2015,7 +2007,6 @@ public void run() {
   }
 
   @GwtIncompatible // threads
-
   public void testScheduleAsync_asyncCallable_error() throws InterruptedException {
     final Error error = new Error("deliberate");
     AsyncCallable<Integer> callable =
@@ -2037,14 +2028,10 @@ public ListenableFuture<Integer> call() {
   }
 
   @GwtIncompatible // threads
-
   public void testScheduleAsync_asyncCallable_nullInsteadOfFuture() throws Exception {
     ListenableFuture<?> chainedFuture =
         scheduleAsync(
-            constantAsyncCallable(null),
-            1,
-            TimeUnit.NANOSECONDS,
-            newSingleThreadScheduledExecutor());
+            constantAsyncCallable(null), 1, NANOSECONDS, newSingleThreadScheduledExecutor());
     try {
       chainedFuture.get();
       fail();
@@ -2059,7 +2046,6 @@ public void testScheduleAsync_asyncCallable_nullInsteadOfFuture() throws Excepti
   }
 
   @GwtIncompatible // threads
-
   public void testScheduleAsync_asyncCallable_cancelledWhileApplyingFunction()
       throws InterruptedException, ExecutionException {
     final CountDownLatch inFunction = new CountDownLatch(1);
@@ -2075,7 +2061,7 @@ public ListenableFuture<Integer> call() throws InterruptedException {
           }
         };
     ListenableFuture<Integer> future =
-        scheduleAsync(callable, 1, TimeUnit.NANOSECONDS, newSingleThreadScheduledExecutor());
+        scheduleAsync(callable, 1, NANOSECONDS, newSingleThreadScheduledExecutor());
     inFunction.await();
     future.cancel(false);
     callableDone.countDown();
@@ -2092,7 +2078,6 @@ public ListenableFuture<Integer> call() throws InterruptedException {
   }
 
   @GwtIncompatible // threads
-
   public void testScheduleAsync_asyncCallable_cancelledBeforeCallingFunction()
       throws InterruptedException {
     final AtomicBoolean callableCalled = new AtomicBoolean();
@@ -2114,7 +2099,7 @@ public void run() {
             awaitUninterruptibly(beforeFunction);
           }
         });
-    ListenableFuture<Integer> future = scheduleAsync(callable, 1, TimeUnit.NANOSECONDS, executor);
+    ListenableFuture<Integer> future = scheduleAsync(callable, 1, NANOSECONDS, executor);
     future.cancel(false);
 
     // Unpause the executor.
@@ -2547,7 +2532,6 @@ private static String createCombinedResult(Integer i, Boolean b) {
   }
 
   @GwtIncompatible // threads
-
   public void testWhenAllComplete_noLeakInterruption() throws Exception {
     final SettableFuture<String> stringFuture = SettableFuture.create();
     AsyncCallable<String> combiner =
@@ -2591,7 +2575,6 @@ public String call() throws Exception {
   }
 
   @GwtIncompatible // threads
-
   public void testWhenAllComplete_asyncResult() throws Exception {
     SettableFuture<Integer> futureInteger = SettableFuture.create();
     SettableFuture<Boolean> futureBoolean = SettableFuture.create();
@@ -2683,7 +2666,6 @@ public ListenableFuture<String> call() throws Exception {
   }
 
   @GwtIncompatible // threads
-
   public void testWhenAllComplete_cancelledNotInterrupted() throws Exception {
     SettableFuture<String> stringFuture = SettableFuture.create();
     SettableFuture<Boolean> booleanFuture = SettableFuture.create();
@@ -2722,7 +2704,6 @@ public ListenableFuture<String> call() throws Exception {
   }
 
   @GwtIncompatible // threads
-
   public void testWhenAllComplete_interrupted() throws Exception {
     SettableFuture<String> stringFuture = SettableFuture.create();
     SettableFuture<Boolean> booleanFuture = SettableFuture.create();
@@ -2815,7 +2796,6 @@ public void run() {
   }
 
   @GwtIncompatible // threads
-
   public void testWhenAllCompleteRunnable_resultCanceledWithoutInterrupt_doesNotInterruptRunnable()
       throws Exception {
     SettableFuture<String> stringFuture = SettableFuture.create();
@@ -2856,7 +2836,6 @@ public void run() {
   }
 
   @GwtIncompatible // threads
-
   public void testWhenAllCompleteRunnable_resultCanceledWithInterrupt_InterruptsRunnable()
       throws Exception {
     SettableFuture<String> stringFuture = SettableFuture.create();
@@ -3375,13 +3354,11 @@ private static List<String> conditionalPseudoTimedGetUninterruptibly(
         : pseudoTimedGetUninterruptibly(future, 2500, MILLISECONDS);
   }
 
-
   @GwtIncompatible // threads
   public void testAllAsList_extensive() throws InterruptedException {
     runExtensiveMergerTest(Merger.allMerger);
   }
 
-
   @GwtIncompatible // threads
   public void testSuccessfulAsList_extensive() throws InterruptedException {
     runExtensiveMergerTest(Merger.successMerger);
diff --git a/guava-tests/test/com/google/common/util/concurrent/FuturesTransformAsyncTest.java b/guava-tests/test/com/google/common/util/concurrent/FuturesTransformAsyncTest.java
index d0fcee2384be..24990200df04 100644
--- a/guava-tests/test/com/google/common/util/concurrent/FuturesTransformAsyncTest.java
+++ b/guava-tests/test/com/google/common/util/concurrent/FuturesTransformAsyncTest.java
@@ -131,7 +131,6 @@ public void testFutureCancellableBeforeOutputCompletion() throws Exception {
     }
   }
 
-
   public void testFutureCancellableBeforeFunctionCompletion() throws Exception {
     // Set the result in a separate thread since this test runs the function
     // (which will block) in the same thread.
diff --git a/guava-tests/test/com/google/common/util/concurrent/GeneratedMonitorTest.java b/guava-tests/test/com/google/common/util/concurrent/GeneratedMonitorTest.java
index 4e2c85efd3b7..8b5caebf51fb 100644
--- a/guava-tests/test/com/google/common/util/concurrent/GeneratedMonitorTest.java
+++ b/guava-tests/test/com/google/common/util/concurrent/GeneratedMonitorTest.java
@@ -46,7 +46,6 @@
  *
  * @author Justin T. Sampson
  */
-
 public class GeneratedMonitorTest extends TestCase {
 
   public static TestSuite suite() {
diff --git a/guava-tests/test/com/google/common/util/concurrent/InterruptibleMonitorTest.java b/guava-tests/test/com/google/common/util/concurrent/InterruptibleMonitorTest.java
index 4d7a45f9c46e..bb3b43b9d16b 100644
--- a/guava-tests/test/com/google/common/util/concurrent/InterruptibleMonitorTest.java
+++ b/guava-tests/test/com/google/common/util/concurrent/InterruptibleMonitorTest.java
@@ -22,7 +22,6 @@
  *
  * @author Justin T. Sampson
  */
-
 public class InterruptibleMonitorTest extends MonitorTestCase {
 
   public InterruptibleMonitorTest() {
diff --git a/guava-tests/test/com/google/common/util/concurrent/InterruptibleTaskTest.java b/guava-tests/test/com/google/common/util/concurrent/InterruptibleTaskTest.java
index a8e098955c36..fcfe744e05ac 100644
--- a/guava-tests/test/com/google/common/util/concurrent/InterruptibleTaskTest.java
+++ b/guava-tests/test/com/google/common/util/concurrent/InterruptibleTaskTest.java
@@ -17,13 +17,14 @@
 
 import static com.google.common.truth.Truth.assertThat;
 
+import java.lang.reflect.Method;
 import java.nio.channels.spi.AbstractInterruptibleChannel;
 import java.util.concurrent.CountDownLatch;
 import java.util.concurrent.TimeUnit;
+import java.util.concurrent.locks.AbstractOwnableSynchronizer;
 import java.util.concurrent.locks.LockSupport;
 import junit.framework.TestCase;
 
-
 public final class InterruptibleTaskTest extends TestCase {
 
   // Regression test for a deadlock where a task could be stuck busy waiting for the task to
@@ -52,7 +53,10 @@ String toPendingString() {
           }
 
           @Override
-          void afterRanInterruptibly(Void result, Throwable error) {}
+          void afterRanInterruptiblySuccess(Void result) {}
+
+          @Override
+          void afterRanInterruptiblyFailure(Throwable error) {}
         };
     Thread runner = new Thread(task);
     runner.start();
@@ -86,6 +90,14 @@ void doBegin() {
    * protect ourselves from that we want to make sure that tasks don't spin too much waiting for the
    * interrupting thread to complete the protocol.
    */
+  /*
+   * This test hangs (or maybe is just *very* slow) under Android.
+   *
+   * TODO(b/218700094): Ideally, get this to pass under Android. Failing that, convince ourselves
+   * that the test isn't exposing a real problem with InterruptibleTask, one that could matter in
+   * prod.
+   */
+  @AndroidIncompatible
   public void testInterruptIsSlow() throws Exception {
     final CountDownLatch isInterruptibleRegistered = new CountDownLatch(1);
     final SlowChannel slowChannel = new SlowChannel();
@@ -115,25 +127,38 @@ String toPendingString() {
           }
 
           @Override
-          void afterRanInterruptibly(Void result, Throwable error) {}
+          void afterRanInterruptiblySuccess(Void result) {}
+
+          @Override
+          void afterRanInterruptiblyFailure(Throwable error) {}
         };
     Thread runner = new Thread(task, "runner");
     runner.start();
     isInterruptibleRegistered.await();
     // trigger the interrupt on another thread since it will block
-    new Thread("Interrupter") {
-      @Override
-      public void run() {
-        task.interruptTask();
-      }
-    }.start();
+    Thread interrupter =
+        new Thread("Interrupter") {
+          @Override
+          public void run() {
+            task.interruptTask();
+          }
+        };
+    interrupter.start();
     // this will happen once the interrupt has been set which means that
     // 1. the runner has been woken up
     // 2. the interrupter is stuck in the call the Thread.interrupt()
 
     // after some period of time the runner thread should become blocked on the task because it is
     // waiting for the slow interrupting thread to complete Thread.interrupt
-    awaitBlockedOn(runner, task);
+    awaitBlockedOnInstanceOf(runner, InterruptibleTask.Blocker.class);
+
+    Object blocker = LockSupport.getBlocker(runner);
+    assertThat(blocker).isInstanceOf(AbstractOwnableSynchronizer.class);
+    Method getExclusiveOwnerThread =
+        AbstractOwnableSynchronizer.class.getDeclaredMethod("getExclusiveOwnerThread");
+    getExclusiveOwnerThread.setAccessible(true);
+    Thread owner = (Thread) getExclusiveOwnerThread.invoke(blocker);
+    assertThat(owner).isSameInstanceAs(interrupter);
 
     slowChannel.exitClose.countDown(); // release the interrupter
 
@@ -143,8 +168,9 @@ public void run() {
   }
 
   // waits for the given thread to be blocked on the given object
-  private static void awaitBlockedOn(Thread t, Object blocker) throws InterruptedException {
-    while (!isThreadBlockedOn(t, blocker)) {
+  private static void awaitBlockedOnInstanceOf(Thread t, Class<?> blocker)
+      throws InterruptedException {
+    while (!isThreadBlockedOnInstanceOf(t, blocker)) {
       if (t.getState() == Thread.State.TERMINATED) {
         throw new RuntimeException("Thread " + t + " exited unexpectedly");
       }
@@ -152,8 +178,8 @@ private static void awaitBlockedOn(Thread t, Object blocker) throws InterruptedE
     }
   }
 
-  private static boolean isThreadBlockedOn(Thread t, Object blocker) {
-    return t.getState() == Thread.State.WAITING && LockSupport.getBlocker(t) == blocker;
+  private static boolean isThreadBlockedOnInstanceOf(Thread t, Class<?> blocker) {
+    return t.getState() == Thread.State.WAITING && blocker.isInstance(LockSupport.getBlocker(t));
   }
 
   static final class SlowChannel extends AbstractInterruptibleChannel {
diff --git a/guava-tests/test/com/google/common/util/concurrent/JSR166TestCase.java b/guava-tests/test/com/google/common/util/concurrent/JSR166TestCase.java
index 8df7ce955821..1825c08ea649 100644
--- a/guava-tests/test/com/google/common/util/concurrent/JSR166TestCase.java
+++ b/guava-tests/test/com/google/common/util/concurrent/JSR166TestCase.java
@@ -682,7 +682,7 @@ void waitForThreadToEnterWaitState(Thread thread) {
 
   /**
    * Returns the number of milliseconds since time given by startNanoTime, which must have been
-   * previously returned from a call to {@link System.nanoTime()}.
+   * previously returned from a call to {@link System#nanoTime()}.
    */
   long millisElapsedSince(long startNanoTime) {
     return NANOSECONDS.toMillis(System.nanoTime() - startNanoTime);
diff --git a/guava-tests/test/com/google/common/util/concurrent/JdkFutureAdaptersTest.java b/guava-tests/test/com/google/common/util/concurrent/JdkFutureAdaptersTest.java
index 3bb819a349fd..741ff45de8c0 100644
--- a/guava-tests/test/com/google/common/util/concurrent/JdkFutureAdaptersTest.java
+++ b/guava-tests/test/com/google/common/util/concurrent/JdkFutureAdaptersTest.java
@@ -100,7 +100,6 @@ public void testListenInPoolThreadIgnoresExecutorWhenDelegateIsDone() throws Exc
     assertTrue(listenableFuture.isDone());
   }
 
-
   public void testListenInPoolThreadUsesGivenExecutor() throws Exception {
     ExecutorService executorService =
         newCachedThreadPool(new ThreadFactoryBuilder().setDaemon(true).build());
@@ -125,7 +124,6 @@ public void testListenInPoolThreadUsesGivenExecutor() throws Exception {
     assertTrue(listenableFuture.isDone());
   }
 
-
   public void testListenInPoolThreadCustomExecutorInterrupted() throws Exception {
     final CountDownLatch submitSuccessful = new CountDownLatch(1);
     ExecutorService executorService =
@@ -235,7 +233,6 @@ public synchronized void run() {
     }
   }
 
-
   @SuppressWarnings("IsInstanceIncompatibleType") // intentional.
   public void testListenInPoolThreadRunsListenerAfterRuntimeException() throws Exception {
     RuntimeExceptionThrowingFuture<String> input = new RuntimeExceptionThrowingFuture<>();
diff --git a/guava-tests/test/com/google/common/util/concurrent/ListenableFutureTaskTest.java b/guava-tests/test/com/google/common/util/concurrent/ListenableFutureTaskTest.java
index 8969a7574d04..fd51a7329fd7 100644
--- a/guava-tests/test/com/google/common/util/concurrent/ListenableFutureTaskTest.java
+++ b/guava-tests/test/com/google/common/util/concurrent/ListenableFutureTaskTest.java
@@ -80,7 +80,6 @@ protected void tearDown() throws Exception {
     super.tearDown();
   }
 
-
   public void testListenerDoesNotRunUntilTaskCompletes() throws Exception {
 
     // Test default state of not started.
@@ -106,7 +105,6 @@ public void testListenerDoesNotRunUntilTaskCompletes() throws Exception {
     assertFalse(task.isCancelled());
   }
 
-
   public void testListenerCalledOnException() throws Exception {
     throwException = true;
 
@@ -142,7 +140,6 @@ public void testListenerCalledOnCancelFromNotRunning() throws Exception {
     assertEquals(1, runLatch.getCount());
   }
 
-
   public void testListenerCalledOnCancelFromRunning() throws Exception {
     exec.execute(task);
     runLatch.await();
diff --git a/guava-tests/test/com/google/common/util/concurrent/ListenerCallQueueTest.java b/guava-tests/test/com/google/common/util/concurrent/ListenerCallQueueTest.java
index 5fd9b950855b..e0eb32e6a54f 100644
--- a/guava-tests/test/com/google/common/util/concurrent/ListenerCallQueueTest.java
+++ b/guava-tests/test/com/google/common/util/concurrent/ListenerCallQueueTest.java
@@ -129,7 +129,6 @@ public void testEnqueueAndDispatch_withLabeledExceptions() {
         logHandler.getStoredLogRecords().get(0).getMessage());
   }
 
-
   public void testEnqueueAndDispatch_multithreaded() throws InterruptedException {
     Object listener = new Object();
     ExecutorService service = Executors.newFixedThreadPool(4);
@@ -153,7 +152,6 @@ public void testEnqueueAndDispatch_multithreaded() throws InterruptedException {
     }
   }
 
-
   public void testEnqueueAndDispatch_multithreaded_withThrowingRunnable()
       throws InterruptedException {
     Object listener = new Object();
diff --git a/guava-tests/test/com/google/common/util/concurrent/MonitorTestCase.java b/guava-tests/test/com/google/common/util/concurrent/MonitorTestCase.java
index a9ead52bb460..44f8d31f2896 100644
--- a/guava-tests/test/com/google/common/util/concurrent/MonitorTestCase.java
+++ b/guava-tests/test/com/google/common/util/concurrent/MonitorTestCase.java
@@ -26,7 +26,6 @@
  *
  * @author Justin T. Sampson
  */
-
 public abstract class MonitorTestCase extends TestCase {
 
   public class TestGuard extends Monitor.Guard {
diff --git a/guava-tests/test/com/google/common/util/concurrent/MoreExecutorsTest.java b/guava-tests/test/com/google/common/util/concurrent/MoreExecutorsTest.java
index fe4e7f540038..aac61735e998 100644
--- a/guava-tests/test/com/google/common/util/concurrent/MoreExecutorsTest.java
+++ b/guava-tests/test/com/google/common/util/concurrent/MoreExecutorsTest.java
@@ -88,7 +88,6 @@ public class MoreExecutorsTest extends JSR166TestCase {
         public void run() {}
       };
 
-
   public void testDirectExecutorServiceServiceInThreadExecution() throws Exception {
     final ListeningExecutorService executor = newDirectExecutorService();
     final ThreadLocal<Integer> threadLocalCount =
@@ -168,7 +167,6 @@ public Integer call() {
     assertEquals(10, threadLocalCount.get().intValue());
   }
 
-
   public void testDirectExecutorServiceServiceTermination() throws Exception {
     final ExecutorService executor = newDirectExecutorService();
     final CyclicBarrier barrier = new CyclicBarrier(2);
@@ -259,7 +257,6 @@ public Void call() throws Exception {
    * Test for a bug where threads weren't getting signaled when shutdown was called, only when tasks
    * completed.
    */
-
   public void testDirectExecutorService_awaitTermination_missedSignal() {
     final ExecutorService service = MoreExecutors.newDirectExecutorService();
     Thread waiter =
@@ -342,6 +339,7 @@ public void testListeningDecorator() throws Exception {
      */
   }
 
+  @AndroidIncompatible // Mocking ExecutorService is forbidden there. TODO(b/218700094): Don't mock.
   public void testListeningDecorator_noWrapExecuteTask() {
     ExecutorService delegate = mock(ExecutorService.class);
     ListeningExecutorService service = listeningDecorator(delegate);
@@ -354,7 +352,6 @@ public void run() {}
     verify(delegate).execute(task);
   }
 
-
   public void testListeningDecorator_scheduleSuccess() throws Exception {
     final CountDownLatch completed = new CountDownLatch(1);
     ScheduledThreadPoolExecutor delegate =
@@ -380,7 +377,6 @@ protected void afterExecute(Runnable r, Throwable t) {
     assertEquals(0, delegate.getQueue().size());
   }
 
-
   public void testListeningDecorator_scheduleFailure() throws Exception {
     ScheduledThreadPoolExecutor delegate = new ScheduledThreadPoolExecutor(1);
     ListeningScheduledExecutorService service = listeningDecorator(delegate);
@@ -391,7 +387,6 @@ public void testListeningDecorator_scheduleFailure() throws Exception {
     assertEquals(0, delegate.getQueue().size());
   }
 
-
   public void testListeningDecorator_schedulePeriodic() throws Exception {
     ScheduledThreadPoolExecutor delegate = new ScheduledThreadPoolExecutor(1);
     ListeningScheduledExecutorService service = listeningDecorator(delegate);
@@ -412,7 +407,6 @@ public void testListeningDecorator_schedulePeriodic() throws Exception {
     assertEquals(0, delegate.getQueue().size());
   }
 
-
   public void testListeningDecorator_cancelled() throws Exception {
     ScheduledThreadPoolExecutor delegate = new ScheduledThreadPoolExecutor(1);
     BlockingQueue<?> delegateQueue = delegate.getQueue();
@@ -566,7 +560,7 @@ public void run() {
     }
   }
 
-
+  @AndroidIncompatible // Mocking ExecutorService is forbidden there. TODO(b/218700094): Don't mock.
   public void testAddDelayedShutdownHook_success() throws InterruptedException {
     TestApplication application = new TestApplication();
     ExecutorService service = mock(ExecutorService.class);
@@ -578,7 +572,7 @@ public void testAddDelayedShutdownHook_success() throws InterruptedException {
     shutdownFirst.verify(service).awaitTermination(2, TimeUnit.SECONDS);
   }
 
-
+  @AndroidIncompatible // Mocking ExecutorService is forbidden there. TODO(b/218700094): Don't mock.
   public void testAddDelayedShutdownHook_interrupted() throws InterruptedException {
     TestApplication application = new TestApplication();
     ExecutorService service = mock(ExecutorService.class);
@@ -588,7 +582,6 @@ public void testAddDelayedShutdownHook_interrupted() throws InterruptedException
     verify(service).shutdown();
   }
 
-
   public void testGetExitingExecutorService_executorSetToUseDaemonThreads() {
     TestApplication application = new TestApplication();
     ThreadPoolExecutor executor =
@@ -597,7 +590,7 @@ public void testGetExitingExecutorService_executorSetToUseDaemonThreads() {
     assertTrue(executor.getThreadFactory().newThread(EMPTY_RUNNABLE).isDaemon());
   }
 
-
+  @AndroidIncompatible // Mocking ExecutorService is forbidden there. TODO(b/218700094): Don't mock.
   public void testGetExitingExecutorService_executorDelegatesToOriginal() {
     TestApplication application = new TestApplication();
     ThreadPoolExecutor executor = mock(ThreadPoolExecutor.class);
@@ -607,7 +600,7 @@ public void testGetExitingExecutorService_executorDelegatesToOriginal() {
     verify(executor).execute(EMPTY_RUNNABLE);
   }
 
-
+  @AndroidIncompatible // Mocking ExecutorService is forbidden there. TODO(b/218700094): Don't mock.
   public void testGetExitingExecutorService_shutdownHookRegistered() throws InterruptedException {
     TestApplication application = new TestApplication();
     ThreadPoolExecutor executor = mock(ThreadPoolExecutor.class);
@@ -618,7 +611,6 @@ public void testGetExitingExecutorService_shutdownHookRegistered() throws Interr
     verify(executor).shutdown();
   }
 
-
   public void testGetExitingScheduledExecutorService_executorSetToUseDaemonThreads() {
     TestApplication application = new TestApplication();
     ScheduledThreadPoolExecutor executor = new ScheduledThreadPoolExecutor(1);
@@ -626,7 +618,7 @@ public void testGetExitingScheduledExecutorService_executorSetToUseDaemonThreads
     assertTrue(executor.getThreadFactory().newThread(EMPTY_RUNNABLE).isDaemon());
   }
 
-
+  @AndroidIncompatible // Mocking ExecutorService is forbidden there. TODO(b/218700094): Don't mock.
   public void testGetExitingScheduledExecutorService_executorDelegatesToOriginal() {
     TestApplication application = new TestApplication();
     ScheduledThreadPoolExecutor executor = mock(ScheduledThreadPoolExecutor.class);
@@ -636,7 +628,7 @@ public void testGetExitingScheduledExecutorService_executorDelegatesToOriginal()
     verify(executor).execute(EMPTY_RUNNABLE);
   }
 
-
+  @AndroidIncompatible // Mocking ExecutorService is forbidden there. TODO(b/218700094): Don't mock.
   public void testGetScheduledExitingExecutorService_shutdownHookRegistered()
       throws InterruptedException {
     TestApplication application = new TestApplication();
@@ -669,7 +661,6 @@ public void run() {
     assertEquals(oldName, Thread.currentThread().getName());
   }
 
-
   public void testExecutors_nullCheck() throws Exception {
     new ClassSanityTester()
         .setDefault(RateLimiter.class, RateLimiter.create(1.0))
@@ -699,14 +690,13 @@ synchronized void shutdown() throws InterruptedException {
   /* Half of a 1-second timeout in nanoseconds */
   private static final long HALF_SECOND_NANOS = NANOSECONDS.convert(1L, SECONDS) / 2;
 
-
   public void testShutdownAndAwaitTermination_immediateShutdown() throws Exception {
     ExecutorService service = Executors.newSingleThreadExecutor();
     assertTrue(shutdownAndAwaitTermination(service, 1L, SECONDS));
     assertTrue(service.isTerminated());
   }
 
-
+  @AndroidIncompatible // Mocking ExecutorService is forbidden there. TODO(b/218700094): Don't mock.
   public void testShutdownAndAwaitTermination_immediateShutdownInternal() throws Exception {
     ExecutorService service = mock(ExecutorService.class);
     when(service.awaitTermination(HALF_SECOND_NANOS, NANOSECONDS)).thenReturn(true);
@@ -716,7 +706,7 @@ public void testShutdownAndAwaitTermination_immediateShutdownInternal() throws E
     verify(service).awaitTermination(HALF_SECOND_NANOS, NANOSECONDS);
   }
 
-
+  @AndroidIncompatible // Mocking ExecutorService is forbidden there. TODO(b/218700094): Don't mock.
   public void testShutdownAndAwaitTermination_forcedShutDownInternal() throws Exception {
     ExecutorService service = mock(ExecutorService.class);
     when(service.awaitTermination(HALF_SECOND_NANOS, NANOSECONDS))
@@ -729,7 +719,7 @@ public void testShutdownAndAwaitTermination_forcedShutDownInternal() throws Exce
     verify(service).shutdownNow();
   }
 
-
+  @AndroidIncompatible // Mocking ExecutorService is forbidden there. TODO(b/218700094): Don't mock.
   public void testShutdownAndAwaitTermination_nonTerminationInternal() throws Exception {
     ExecutorService service = mock(ExecutorService.class);
     when(service.awaitTermination(HALF_SECOND_NANOS, NANOSECONDS))
@@ -741,7 +731,7 @@ public void testShutdownAndAwaitTermination_nonTerminationInternal() throws Exce
     verify(service).shutdownNow();
   }
 
-
+  @AndroidIncompatible // Mocking ExecutorService is forbidden there. TODO(b/218700094): Don't mock.
   public void testShutdownAndAwaitTermination_interruptedInternal() throws Exception {
     final ExecutorService service = mock(ExecutorService.class);
     when(service.awaitTermination(HALF_SECOND_NANOS, NANOSECONDS))
diff --git a/guava-tests/test/com/google/common/util/concurrent/SequentialExecutorTest.java b/guava-tests/test/com/google/common/util/concurrent/SequentialExecutorTest.java
index 20209e8b80dc..80e7ab2e1241 100644
--- a/guava-tests/test/com/google/common/util/concurrent/SequentialExecutorTest.java
+++ b/guava-tests/test/com/google/common/util/concurrent/SequentialExecutorTest.java
@@ -274,7 +274,14 @@ public void run() {
     assertEquals(1, numCalls.get());
   }
 
-
+  /*
+   * Under Android, MyError propagates up and fails the test?
+   *
+   * TODO(b/218700094): Does this matter to prod users, or is it just a feature of our testing
+   * environment? If the latter, maybe write a custom Executor that avoids failing the test when it
+   * sees an Error?
+   */
+  @AndroidIncompatible
   public void testTaskThrowsError() throws Exception {
     class MyError extends Error {}
     final CyclicBarrier barrier = new CyclicBarrier(2);
@@ -313,7 +320,6 @@ public void run() {
     }
   }
 
-
   public void testRejectedExecutionThrownWithMultipleCalls() throws Exception {
     final CountDownLatch latch = new CountDownLatch(1);
     final SettableFuture<?> future = SettableFuture.create();
diff --git a/guava-tests/test/com/google/common/util/concurrent/ServiceManagerTest.java b/guava-tests/test/com/google/common/util/concurrent/ServiceManagerTest.java
index 2092aff52887..9f89fb1b36d4 100644
--- a/guava-tests/test/com/google/common/util/concurrent/ServiceManagerTest.java
+++ b/guava-tests/test/com/google/common/util/concurrent/ServiceManagerTest.java
@@ -29,6 +29,7 @@
 import com.google.common.testing.TestLogHandler;
 import com.google.common.util.concurrent.Service.State;
 import com.google.common.util.concurrent.ServiceManager.Listener;
+import java.time.Duration;
 import java.util.Arrays;
 import java.util.Collection;
 import java.util.List;
@@ -119,20 +120,27 @@ protected void doStop() {
     }
   }
 
-
   public void testServiceStartupTimes() {
     Service a = new NoOpDelayedService(150);
     Service b = new NoOpDelayedService(353);
     ServiceManager serviceManager = new ServiceManager(asList(a, b));
     serviceManager.startAsync().awaitHealthy();
     ImmutableMap<Service, Long> startupTimes = serviceManager.startupTimes();
-    assertEquals(2, startupTimes.size());
-    // TODO(kak): Use assertThat(startupTimes.get(a)).isAtLeast(150);
-    assertTrue(startupTimes.get(a) >= 150);
-    // TODO(kak): Use assertThat(startupTimes.get(b)).isAtLeast(353);
-    assertTrue(startupTimes.get(b) >= 353);
+    assertThat(startupTimes).hasSize(2);
+    assertThat(startupTimes.get(a)).isAtLeast(150);
+    assertThat(startupTimes.get(b)).isAtLeast(353);
   }
 
+  public void testServiceStartupDurations() {
+    Service a = new NoOpDelayedService(150);
+    Service b = new NoOpDelayedService(353);
+    ServiceManager serviceManager = new ServiceManager(asList(a, b));
+    serviceManager.startAsync().awaitHealthy();
+    ImmutableMap<Service, Duration> startupTimes = serviceManager.startupDurations();
+    assertThat(startupTimes).hasSize(2);
+    assertThat(startupTimes.get(a)).isAtLeast(Duration.ofMillis(150));
+    assertThat(startupTimes.get(b)).isAtLeast(Duration.ofMillis(353));
+  }
 
   public void testServiceStartupTimes_selfStartingServices() {
     // This tests to ensure that:
@@ -159,9 +167,8 @@ protected void doStart() {
     ServiceManager serviceManager = new ServiceManager(asList(a, b));
     serviceManager.startAsync().awaitHealthy();
     ImmutableMap<Service, Long> startupTimes = serviceManager.startupTimes();
-    assertEquals(2, startupTimes.size());
-    // TODO(kak): Use assertThat(startupTimes.get(a)).isAtLeast(150);
-    assertTrue(startupTimes.get(a) >= 150);
+    assertThat(startupTimes).hasSize(2);
+    assertThat(startupTimes.get(a)).isAtLeast(150);
     // Service b startup takes at least 353 millis, but starting the timer is delayed by at least
     // 150 milliseconds. so in a perfect world the timing would be 353-150=203ms, but since either
     // of our sleep calls can be arbitrarily delayed we should just assert that there is a time
@@ -169,7 +176,6 @@ protected void doStart() {
     assertThat(startupTimes.get(b)).isNotNull();
   }
 
-
   public void testServiceStartStop() {
     Service a = new NoOpService();
     Service b = new NoOpService();
@@ -191,7 +197,6 @@ public void testServiceStartStop() {
     assertTrue(listener.failedServices.isEmpty());
   }
 
-
   public void testFailStart() throws Exception {
     Service a = new NoOpService();
     Service b = new FailStartService();
@@ -219,7 +224,6 @@ public void testFailStart() throws Exception {
     assertTrue(listener.stoppedCalled);
   }
 
-
   public void testFailRun() throws Exception {
     Service a = new NoOpService();
     Service b = new FailRunService();
@@ -242,7 +246,6 @@ public void testFailRun() throws Exception {
     assertTrue(listener.stoppedCalled);
   }
 
-
   public void testFailStop() throws Exception {
     Service a = new NoOpService();
     Service b = new FailStopService();
@@ -271,7 +274,6 @@ public void testToString() throws Exception {
     assertThat(toString).contains("FailStartService");
   }
 
-
   public void testTimeouts() throws Exception {
     Service a = new NoOpDelayedService(50);
     ServiceManager manager = new ServiceManager(asList(a));
@@ -448,7 +450,6 @@ public String format(LogRecord record) {
    * Tests that a ServiceManager can be fully shut down if one of its failure listeners is slow or
    * even permanently blocked.
    */
-
   public void testListenerDeadlock() throws InterruptedException {
     final CountDownLatch failEnter = new CountDownLatch(1);
     final CountDownLatch failLeave = new CountDownLatch(1);
@@ -609,7 +610,6 @@ public final Throwable failureCause() {
    *
    * <p>Before the bug was fixed this test would fail at least 30% of the time.
    */
-
   public void testTransitionRace() throws TimeoutException {
     for (int k = 0; k < 1000; k++) {
       List<Service> services = Lists.newArrayList();
diff --git a/guava-tests/test/com/google/common/util/concurrent/SettableFutureTest.java b/guava-tests/test/com/google/common/util/concurrent/SettableFutureTest.java
index 9b8b88f27167..105e8de0410e 100644
--- a/guava-tests/test/com/google/common/util/concurrent/SettableFutureTest.java
+++ b/guava-tests/test/com/google/common/util/concurrent/SettableFutureTest.java
@@ -51,19 +51,16 @@ public void testDefaultState() throws Exception {
     }
   }
 
-
   public void testSetValue() throws Exception {
     assertTrue(future.set("value"));
     tester.testCompletedFuture("value");
   }
 
-
   public void testSetFailure() throws Exception {
     assertTrue(future.setException(new Exception("failure")));
     tester.testFailedFuture("failure");
   }
 
-
   public void testSetFailureNull() throws Exception {
     try {
       future.setException(null);
@@ -75,7 +72,6 @@ public void testSetFailureNull() throws Exception {
     tester.testFailedFuture("failure");
   }
 
-
   public void testCancel() throws Exception {
     assertTrue(future.cancel(true));
     tester.testCancelledFuture();
diff --git a/guava-tests/test/com/google/common/util/concurrent/SimpleTimeLimiterTest.java b/guava-tests/test/com/google/common/util/concurrent/SimpleTimeLimiterTest.java
index 04b824f823f9..35406864dce4 100644
--- a/guava-tests/test/com/google/common/util/concurrent/SimpleTimeLimiterTest.java
+++ b/guava-tests/test/com/google/common/util/concurrent/SimpleTimeLimiterTest.java
@@ -34,7 +34,6 @@
  * @author kevinb
  * @author Jens Nyman
  */
-
 public class SimpleTimeLimiterTest extends TestCase {
 
   private static final long DELAY_MS = 50;
diff --git a/guava-tests/test/com/google/common/util/concurrent/StripedTest.java b/guava-tests/test/com/google/common/util/concurrent/StripedTest.java
index fa9d87f752f2..688d6fd34ac0 100644
--- a/guava-tests/test/com/google/common/util/concurrent/StripedTest.java
+++ b/guava-tests/test/com/google/common/util/concurrent/StripedTest.java
@@ -129,7 +129,7 @@ public void testSizes() {
     assertTrue(Striped.lazyWeakLock(256).size() == 256);
   }
 
-
+  @AndroidIncompatible // Presumably GC doesn't trigger, despite our efforts.
   public void testWeakImplementations() {
     for (Striped<?> striped : weakImplementations()) {
       WeakReference<Object> weakRef = new WeakReference<>(striped.get(new Object()));
@@ -137,7 +137,7 @@ public void testWeakImplementations() {
     }
   }
 
-
+  @AndroidIncompatible // Presumably GC doesn't trigger, despite our efforts.
   public void testWeakReadWrite() {
     Striped<ReadWriteLock> striped = Striped.lazyWeakReadWriteLock(1000);
     Object key = new Object();
@@ -150,7 +150,7 @@ public void testWeakReadWrite() {
     readLock.unlock();
   }
 
-
+  @AndroidIncompatible // Presumably GC doesn't trigger, despite our efforts.
   public void testStrongImplementations() {
     for (Striped<?> striped : strongImplementations()) {
       WeakReference<Object> weakRef = new WeakReference<>(striped.get(new Object()));
diff --git a/guava-tests/test/com/google/common/util/concurrent/SupplementalMonitorTest.java b/guava-tests/test/com/google/common/util/concurrent/SupplementalMonitorTest.java
index 8a52ffeed591..5b77f9a59ef5 100644
--- a/guava-tests/test/com/google/common/util/concurrent/SupplementalMonitorTest.java
+++ b/guava-tests/test/com/google/common/util/concurrent/SupplementalMonitorTest.java
@@ -33,7 +33,6 @@
  *
  * @author Justin T. Sampson
  */
-
 public class SupplementalMonitorTest extends TestCase {
 
   public void testLeaveWithoutEnterThrowsIMSE() {
diff --git a/guava-tests/test/com/google/common/util/concurrent/ThreadFactoryBuilderTest.java b/guava-tests/test/com/google/common/util/concurrent/ThreadFactoryBuilderTest.java
index 7684b963376a..a3a7b8e79dcc 100644
--- a/guava-tests/test/com/google/common/util/concurrent/ThreadFactoryBuilderTest.java
+++ b/guava-tests/test/com/google/common/util/concurrent/ThreadFactoryBuilderTest.java
@@ -56,7 +56,6 @@ public void setUp() {
     builder = new ThreadFactoryBuilder();
   }
 
-
   public void testThreadFactoryBuilder_defaults() throws InterruptedException {
     ThreadFactory threadFactory = builder.build();
     Thread thread = threadFactory.newThread(monitoredRunnable);
@@ -93,7 +92,6 @@ private static void checkThreadPoolName(Thread thread, int threadId) {
     assertThat(thread.getName()).matches("^pool-\\d+-thread-" + threadId + "$");
   }
 
-
   public void testNameFormatWithPercentS_custom() {
     String format = "super-duper-thread-%s";
     ThreadFactory factory = builder.setNameFormat(format).build();
@@ -102,7 +100,6 @@ public void testNameFormatWithPercentS_custom() {
     }
   }
 
-
   public void testNameFormatWithPercentD_custom() {
     String format = "super-duper-thread-%d";
     ThreadFactory factory = builder.setNameFormat(format).build();
@@ -111,21 +108,18 @@ public void testNameFormatWithPercentD_custom() {
     }
   }
 
-
   public void testDaemon_false() {
     ThreadFactory factory = builder.setDaemon(false).build();
     Thread thread = factory.newThread(monitoredRunnable);
     assertFalse(thread.isDaemon());
   }
 
-
   public void testDaemon_true() {
     ThreadFactory factory = builder.setDaemon(true).build();
     Thread thread = factory.newThread(monitoredRunnable);
     assertTrue(thread.isDaemon());
   }
 
-
   public void testPriority_custom() {
     for (int i = Thread.MIN_PRIORITY; i <= Thread.MAX_PRIORITY; i++) {
       ThreadFactory factory = builder.setPriority(i).build();
@@ -150,7 +144,6 @@ public void testPriority_tooHigh() {
     }
   }
 
-
   public void testUncaughtExceptionHandler_custom() {
     assertEquals(
         UNCAUGHT_EXCEPTION_HANDLER,
@@ -161,7 +154,6 @@ public void testUncaughtExceptionHandler_custom() {
             .getUncaughtExceptionHandler());
   }
 
-
   public void testBuildMutateBuild() {
     ThreadFactory factory1 = builder.setPriority(1).build();
     assertEquals(1, factory1.newThread(monitoredRunnable).getPriority());
@@ -177,7 +169,6 @@ public void testBuildTwice() {
     unused = builder.build(); // this is *also* allowed
   }
 
-
   public void testBuildMutate() {
     ThreadFactory factory1 = builder.setPriority(1).build();
     assertEquals(1, factory1.newThread(monitoredRunnable).getPriority());
@@ -186,7 +177,6 @@ public void testBuildMutate() {
     assertEquals(1, factory1.newThread(monitoredRunnable).getPriority());
   }
 
-
   public void testThreadFactory() throws InterruptedException {
     final String THREAD_NAME = "ludicrous speed";
     final int THREAD_PRIORITY = 1;
diff --git a/guava-tests/test/com/google/common/util/concurrent/TrustedListenableFutureTaskTest.java b/guava-tests/test/com/google/common/util/concurrent/TrustedListenableFutureTaskTest.java
index 157afa79d8a6..e735ae02a43c 100644
--- a/guava-tests/test/com/google/common/util/concurrent/TrustedListenableFutureTaskTest.java
+++ b/guava-tests/test/com/google/common/util/concurrent/TrustedListenableFutureTaskTest.java
@@ -84,7 +84,6 @@ public Integer call() throws Exception {
   }
 
   @GwtIncompatible // blocking wait
-
   public void testCancel_interrupted() throws Exception {
     final AtomicBoolean interruptedExceptionThrown = new AtomicBoolean();
     final CountDownLatch enterLatch = new CountDownLatch(1);
@@ -135,7 +134,6 @@ public void run() {
   }
 
   @GwtIncompatible // blocking wait
-
   public void testRunIdempotency() throws Exception {
     final int numThreads = 10;
     final ExecutorService executor = Executors.newFixedThreadPool(numThreads);
@@ -171,7 +169,6 @@ public void run() {
   }
 
   @GwtIncompatible // blocking wait
-
   public void testToString() throws Exception {
     final CountDownLatch enterLatch = new CountDownLatch(1);
     final CountDownLatch exitLatch = new CountDownLatch(1);
diff --git a/guava-tests/test/com/google/common/util/concurrent/UncaughtExceptionHandlersTest.java b/guava-tests/test/com/google/common/util/concurrent/UncaughtExceptionHandlersTest.java
index eb8455b18323..4a26b4976578 100644
--- a/guava-tests/test/com/google/common/util/concurrent/UncaughtExceptionHandlersTest.java
+++ b/guava-tests/test/com/google/common/util/concurrent/UncaughtExceptionHandlersTest.java
@@ -23,7 +23,6 @@
 import junit.framework.TestCase;
 
 /** @author Gregory Kick */
-
 public class UncaughtExceptionHandlersTest extends TestCase {
 
   private Runtime runtimeMock;
diff --git a/guava-tests/test/com/google/common/util/concurrent/UninterruptibleFutureTest.java b/guava-tests/test/com/google/common/util/concurrent/UninterruptibleFutureTest.java
index 0d24266074b0..3f91b8123bd3 100644
--- a/guava-tests/test/com/google/common/util/concurrent/UninterruptibleFutureTest.java
+++ b/guava-tests/test/com/google/common/util/concurrent/UninterruptibleFutureTest.java
@@ -77,7 +77,6 @@ protected void tearDown() {
    * This first test doesn't test anything in Uninterruptibles, just demonstrates some normal
    * behavior of futures so that you can contrast the next test with it.
    */
-
   public void testRegularFutureInterrupted() throws ExecutionException {
 
     /*
@@ -116,7 +115,6 @@ public void testRegularFutureInterrupted() throws ExecutionException {
     assertTrue(sleeper.completed);
   }
 
-
   public void testMakeUninterruptible_timeoutPreservedThroughInterruption()
       throws ExecutionException {
 
@@ -155,32 +153,26 @@ public void run() {
     }
   }
 
-
   public void testMakeUninterruptible_untimed_uninterrupted() throws Exception {
     runUntimedInterruptsTest(0);
   }
 
-
   public void testMakeUninterruptible_untimed_interrupted() throws Exception {
     runUntimedInterruptsTest(1);
   }
 
-
   public void testMakeUninterruptible_untimed_multiplyInterrupted() throws Exception {
     runUntimedInterruptsTest(38);
   }
 
-
   public void testMakeUninterruptible_timed_uninterrupted() throws Exception {
     runTimedInterruptsTest(0);
   }
 
-
   public void testMakeUninterruptible_timed_interrupted() throws Exception {
     runTimedInterruptsTest(1);
   }
 
-
   public void testMakeUninterruptible_timed_multiplyInterrupted() throws Exception {
     runTimedInterruptsTest(38);
   }
@@ -218,7 +210,6 @@ private static void runNInterruptsTest(
   /**
    * Confirms that the test code triggers {@link InterruptedException} in a standard {@link Future}.
    */
-
   public void testMakeUninterruptible_plainFutureSanityCheck() throws Exception {
     SettableFuture<String> future = SettableFuture.create();
     FutureTask<Boolean> wasInterrupted = untimedInterruptReporter(future, true);
@@ -235,7 +226,6 @@ public void testMakeUninterruptible_plainFutureSanityCheck() throws Exception {
     }
   }
 
-
   public void testMakeUninterruptible_timedGetZeroTimeoutAttempted()
       throws TimeoutException, ExecutionException {
     SettableFuture<String> future = SettableFuture.create();
@@ -248,7 +238,6 @@ public void testMakeUninterruptible_timedGetZeroTimeoutAttempted()
     assertEquals(RESULT, getUninterruptibly(future, 0, SECONDS));
   }
 
-
   public void testMakeUninterruptible_timedGetNegativeTimeoutAttempted()
       throws TimeoutException, ExecutionException {
     SettableFuture<String> future = SettableFuture.create();
diff --git a/guava-tests/test/com/google/common/util/concurrent/UninterruptibleMonitorTest.java b/guava-tests/test/com/google/common/util/concurrent/UninterruptibleMonitorTest.java
index 59bf80878849..3e775bab5676 100644
--- a/guava-tests/test/com/google/common/util/concurrent/UninterruptibleMonitorTest.java
+++ b/guava-tests/test/com/google/common/util/concurrent/UninterruptibleMonitorTest.java
@@ -22,7 +22,6 @@
  *
  * @author Justin T. Sampson
  */
-
 public class UninterruptibleMonitorTest extends MonitorTestCase {
 
   public UninterruptibleMonitorTest() {
diff --git a/guava-tests/test/com/google/common/util/concurrent/UninterruptiblesTest.java b/guava-tests/test/com/google/common/util/concurrent/UninterruptiblesTest.java
index 4343d894dac6..1b6501efedd8 100644
--- a/guava-tests/test/com/google/common/util/concurrent/UninterruptiblesTest.java
+++ b/guava-tests/test/com/google/common/util/concurrent/UninterruptiblesTest.java
@@ -55,7 +55,6 @@
  *
  * @author Anthony Zana
  */
-
 public class UninterruptiblesTest extends TestCase {
   private static final String EXPECTED_TAKE = "expectedTake";
 
diff --git a/guava/pom.xml b/guava/pom.xml
index d0643e25e487..5f2854e01b5c 100644
--- a/guava/pom.xml
+++ b/guava/pom.xml
@@ -5,11 +5,12 @@
   <parent>
     <groupId>com.google.guava</groupId>
     <artifactId>guava-parent</artifactId>
-    <version>30.1.1-jre</version>
+    <version>31.1-jre</version>
   </parent>
   <artifactId>guava</artifactId>
   <packaging>bundle</packaging>
   <name>Guava: Google Core Libraries for Java</name>
+  <url>https://github.com/google/guava</url>
   <description>
     Guava is a suite of core and expanded libraries that include
     utility classes, Google's collections, I/O classes, and
@@ -20,11 +21,17 @@
     <!-- Running the Index Checker takes very long but is needed to put implicit annotations in class files. -->
     <checkerframework.checkers>org.checkerframework.checker.index.IndexChecker,org.checkerframework.checker.nullness.NullnessChecker,org.checkerframework.checker.signedness.SignednessChecker</checkerframework.checkers>
 
-    <!-- Index checker warnings are disabled by default, because not all code is annotated by index checker annotations. -->
+    <!-- Index checker warnings are disabled by default, because not all code is annotated by index checker annotations.
+         Use -Dcheckerframework.suppress=none to show index checker warnings.  -->
     <checkerframework.suppress>index</checkerframework.suppress>
 
-    <!-- Packages under com.google.common, that will be additionally checked by the Index Checker -->
-    <checkerframework.index.packages>base|primitives|escape|math|io|hash</checkerframework.index.packages>
+    <!-- In addition to the normal checkers noted above, we do a quick run of the Value Checker on a subset of the
+         sources for which we expect no errors. Packages under com.google.common that will be value checked:       -->
+    <checkerframework.value.packages>base|cache|escape|hash|io|math|net|primitives|reflect</checkerframework.value.packages>
+    <!-- The phase when the Value Checker is run. Use -Dcheck.value.phase=skip to omit this step.-->
+    <check.value.phase>process-sources</check.value.phase>
+    <!-- Use -Dmain-compile.skip=true to only run the quick Value check execution. -->
+    <main-compile.skip>false</main-compile.skip>
 
     <!-- Additional argument passed to the java compiler. Use to pass additional arguments
          to the checker framework. Example: -Ashowchecks -->
@@ -34,15 +41,6 @@
          to the checker framework. Example: -Aannotations -->
     <checkerframework.extraargs2></checkerframework.extraargs2>
 
-    <!-- The phase when the Index Checker is run. -->
-    <check.index.phase>process-sources</check.index.phase>
-
-    <!-- Additional argument passed to the Index Checker. Example: -Ashowchecks -->
-    <index.only.arg></index.only.arg>
-
-    <!-- Use -Dmain-compile.skip=true to only run the check-index execution -->
-    <main-compile.skip>false</main-compile.skip>
-
     <!-- Use -Djavac.verbose=true to compile with the verbose option.
          This is used when you want to see stub parser warnings. -->
     <javac.verbose>false</javac.verbose>
@@ -66,6 +64,10 @@
       <groupId>org.checkerframework</groupId>
       <artifactId>checker-qual</artifactId>
     </dependency>
+    <dependency>
+      <groupId>org.checkerframework</groupId>
+      <artifactId>checker-util</artifactId>
+    </dependency>
     <dependency>
       <groupId>com.google.errorprone</groupId>
       <artifactId>error_prone_annotations</artifactId>
@@ -89,7 +91,7 @@
     <dependency>
       <groupId>org.checkerframework</groupId>
       <artifactId>checker</artifactId>
-      <version>3.30.0</version>
+      <version>3.32.0</version>
     </dependency>
   </dependencies>
   <build>
@@ -155,32 +157,32 @@
               <arg>${additionalargs}</arg>
               <arg>${checkerframework.extraargs}</arg>
               <arg>${checkerframework.extraargs2}</arg>
-              <!-- Default is supress all index checker warnings! -->
+              <!-- Default is supress all index checker warnings. -->
               <arg>-AsuppressWarnings=${checkerframework.suppress}</arg>
+              <arg>-XDignore.symbol.file</arg>  <!-- suppress any warnings for using 'Unsafe' -->
               <arg>-AuseDefaultsForUncheckedCode=source,bytecode</arg>
-              <arg>-Awarns</arg>
               <arg>-AshowSuppressWarningsStrings</arg>
               <arg>-AwarnUnneededSuppressions</arg>
             </compilerArgs>
         </configuration>
         <executions>
-          <!-- Runs the Index Checker on selected packages. -->
-          <!-- Because Index Checker warnings are suppressed during regular compilation (when all
-               files are compiled), this additional phase runs the Index Checker on packages that
-               are already annotated, to ensure they type-check without warnings. -->
           <execution>
-            <id>check-index</id>
-            <phase>${check.index.phase}</phase>
+            <!-- This initial phase runs the Value Checker on packages that are already annotated
+                 and/or warning suppressed to ensure they continue to type-check without any errors.
+                 If this phase passes, then we run all the selected checkers, but with -Awarns.  -->
+            <id>value-check</id>
+            <phase>${check.value.phase}</phase>
             <goals><goal>compile</goal></goals>
             <configuration>
               <annotationProcessors>
-                <annotationProcessor>org.checkerframework.checker.index.IndexChecker</annotationProcessor>
+                <!-- The Signedness Checker invokes the value checker.  So we run the Signedness Checker but
+                     suppress any signedness warnings so we only see the Value Checker results.              -->
+                <annotationProcessor>org.checkerframework.checker.signedness.SignednessChecker</annotationProcessor>
               </annotationProcessors>
               <compilerArgs combine.children="append">
-                <arg>-XDignore.symbol.file</arg>
-                <arg>${index.only.arg}</arg>
-                <arg>-proc:only</arg>
-                <arg>-AonlyDefs=^com\.google\.common\.(?:${checkerframework.index.packages})\.</arg>
+                <arg>-proc:only</arg>             <!-- run annotation processing but no subsequent compilation -->
+                <arg>-AonlyDefs=^com\.google\.common\.(?:${checkerframework.value.packages})\.</arg>
+                <arg>-AsuppressWarnings=signedness</arg>
               </compilerArgs>
             </configuration>
           </execution>
@@ -204,6 +206,9 @@
               <!-- -source 8 -target 8 is a no-op in the mainline but matters in the backport. -->
               <source>8</source>
               <target>8</target>
+              <compilerArgs combine.children="append">
+                <arg>-Awarns</arg>  <!-- Treat checker errors as warnings. -->
+              </compilerArgs>
             </configuration>
           </execution>
           <execution>
@@ -217,6 +222,9 @@
               <excludes>
                 <exclude>**/Java8Usage.java</exclude>
               </excludes>
+              <compilerArgs combine.children="append">
+                <arg>-Awarns</arg>  <!-- Treat checker errors as warnings. -->
+              </compilerArgs>
             </configuration>
           </execution>
         </executions>
@@ -263,7 +271,7 @@
           <!-- excludePackageNames requires specification of packages separately from "all subpackages".
                https://issues.apache.org/jira/browse/MJAVADOC-584 -->
           <excludePackageNames>
-            com.google.common.base.internal,com.google.common.base.internal.*,com.google.thirdparty.publicsuffix,com.google.thirdparty.publicsuffix.*,com.oracle.*,com.sun.*,java.*,javax.*,jdk,jdk.*,org.*,sun.*
+            com.azul.tooling.in,com.google.common.base.internal,com.google.common.base.internal.*,com.google.thirdparty.publicsuffix,com.google.thirdparty.publicsuffix.*,com.oracle.*,com.sun.*,java.*,javax.*,jdk,jdk.*,org.*,sun.*
           </excludePackageNames>
           <!-- Ignore some tags that are found in Java 11 sources but not recognized... under -source 8, I think it was? I can no longer reproduce the failure. -->
           <tags>
@@ -333,6 +341,20 @@
           </execution>
         </executions>
       </plugin>
+      <plugin>
+        <groupId>org.apache.maven.plugins</groupId>
+        <artifactId>maven-help-plugin</artifactId>
+        <version>3.1.0</version>
+        <executions>
+          <execution>
+            <id>show-profiles</id>
+            <phase>compile</phase>
+            <goals>
+              <goal>active-profiles</goal>
+            </goals>
+          </execution>
+        </executions>
+      </plugin>
     </plugins>
   </build>
   <profiles>
diff --git a/guava/src/com/google/common/base/Absent.java b/guava/src/com/google/common/base/Absent.java
index c8c0b853da1f..65035ae8221b 100644
--- a/guava/src/com/google/common/base/Absent.java
+++ b/guava/src/com/google/common/base/Absent.java
@@ -19,6 +19,7 @@
 import com.google.common.annotations.GwtCompatible;
 import java.util.Collections;
 import java.util.Set;
+import javax.annotation.CheckForNull;
 import org.checkerframework.checker.nullness.qual.NonNull;
 import org.checkerframework.checker.nullness.qual.Nullable;
 import org.checkerframework.checker.nullness.qual.RequiresNonNull;
@@ -27,6 +28,7 @@
 /** Implementation of an {@link Optional} not containing a reference. */
 @AnnotatedFor({"nullness"})
 @GwtCompatible
+@ElementTypesAreNonnullByDefault
 final class Absent<T> extends Optional<T> {
   static final Absent<Object> INSTANCE = new Absent<>();
 
@@ -65,7 +67,8 @@ public Optional<T> or(Optional<? extends T> secondChoice) {
   }
 
   @Override
-  public @Nullable T orNull() {
+  @CheckForNull
+  public T orNull() {
     return null;
   }
 
@@ -81,7 +84,7 @@ public Optional<T> or(Optional<? extends T> secondChoice) {
   }
 
   @Override
-  public boolean equals(@Nullable Object object) {
+  public boolean equals(@CheckForNull Object object) {
     return object == this;
   }
 
diff --git a/guava/src/com/google/common/base/AbstractIterator.java b/guava/src/com/google/common/base/AbstractIterator.java
index 57d8167bcc02..bb0a1d324978 100644
--- a/guava/src/com/google/common/base/AbstractIterator.java
+++ b/guava/src/com/google/common/base/AbstractIterator.java
@@ -14,12 +14,14 @@
 
 package com.google.common.base;
 
+import static com.google.common.base.NullnessCasts.uncheckedCastNullableTToT;
 import static com.google.common.base.Preconditions.checkState;
 
 import com.google.common.annotations.GwtCompatible;
 import com.google.errorprone.annotations.CanIgnoreReturnValue;
 import java.util.Iterator;
 import java.util.NoSuchElementException;
+import javax.annotation.CheckForNull;
 import org.checkerframework.checker.nullness.qual.Nullable;
 
 /**
@@ -27,7 +29,8 @@
  * reasons).
  */
 @GwtCompatible
-abstract class AbstractIterator<T> implements Iterator<T> {
+@ElementTypesAreNonnullByDefault
+abstract class AbstractIterator<T extends @Nullable Object> implements Iterator<T> {
   private State state = State.NOT_READY;
 
   protected AbstractIterator() {}
@@ -39,12 +42,14 @@ private enum State {
     FAILED,
   }
 
-  private @Nullable T next;
+  @CheckForNull private T next;
 
+  @CheckForNull
   protected abstract T computeNext();
 
   @CanIgnoreReturnValue
-  protected final @Nullable T endOfData() {
+  @CheckForNull
+  protected final T endOfData() {
     state = State.DONE;
     return null;
   }
@@ -73,12 +78,14 @@ private boolean tryToComputeNext() {
   }
 
   @Override
+  @ParametricNullness
   public final T next() {
     if (!hasNext()) {
       throw new NoSuchElementException();
     }
     state = State.NOT_READY;
-    T result = next;
+    // Safe because hasNext() ensures that tryToComputeNext() has put a T into `next`.
+    T result = uncheckedCastNullableTToT(next);
     next = null;
     return result;
   }
diff --git a/guava/src/com/google/common/base/Ascii.java b/guava/src/com/google/common/base/Ascii.java
index a6492b5c558e..d5d1266a9cff 100644
--- a/guava/src/com/google/common/base/Ascii.java
+++ b/guava/src/com/google/common/base/Ascii.java
@@ -38,6 +38,7 @@
  * @since 7.0
  */
 @GwtCompatible
+@ElementTypesAreNonnullByDefault
 public final class Ascii {
 
   private Ascii() {}
@@ -442,7 +443,7 @@ public static String toLowerCase(CharSequence chars) {
   }
 
   /**
-   * If the argument is an {@linkplain #isUpperCase(char) uppercase ASCII character} returns the
+   * If the argument is an {@linkplain #isUpperCase(char) uppercase ASCII character}, returns the
    * lowercase equivalent. Otherwise returns the argument.
    */
   @SuppressWarnings("index") // https://github.com/typetools/checker-framework/issues/2540
@@ -493,7 +494,7 @@ public static String toUpperCase(CharSequence chars) {
   }
 
   /**
-   * If the argument is a {@linkplain #isLowerCase(char) lowercase ASCII character} returns the
+   * If the argument is a {@linkplain #isLowerCase(char) lowercase ASCII character}, returns the
    * uppercase equivalent. Otherwise returns the argument.
    */
   @SuppressWarnings("index") // https://github.com/typetools/checker-framework/issues/2540
@@ -553,20 +554,6 @@ public static boolean isUpperCase(char c) {
    *     truncationIndicator}
    * @since 16.0
    */
-  @SuppressWarnings({
-    /*
-     * The parameter maxLength should be annotated something like @GTEqLengthOf("#3").
-     * However, such annotation does not exist, so this property is not expressed.
-     * Lower bound validity:
-     *   truncationIndicator.length <= maxLength,
-     *   therefore truncationLength >= 0
-     * Upper bound validity:
-     *   truncationLength <= maxLength,
-     *   seq.length > maxLength,
-     *   therefore truncationLength <= seq.length
-     */
-    "lowerbound:assignment.type.incompatible", "upperbound:argument.type.incompatible" // https://github.com/kelloggm/checker-framework/issues/220
-  })
   public static String truncate(CharSequence seq, @NonNegative int maxLength, String truncationIndicator) {
     checkNotNull(seq);
 
diff --git a/guava/src/com/google/common/base/CaseFormat.java b/guava/src/com/google/common/base/CaseFormat.java
index 5e36993f4829..5957b92fb075 100644
--- a/guava/src/com/google/common/base/CaseFormat.java
+++ b/guava/src/com/google/common/base/CaseFormat.java
@@ -15,9 +15,11 @@
 package com.google.common.base;
 
 import static com.google.common.base.Preconditions.checkNotNull;
+import static java.util.Objects.requireNonNull;
 
 import com.google.common.annotations.GwtCompatible;
 import java.io.Serializable;
+import javax.annotation.CheckForNull;
 import org.checkerframework.checker.index.qual.GTENegativeOne;
 import org.checkerframework.checker.index.qual.IndexOrHigh;
 import org.checkerframework.checker.index.qual.LTEqLengthOf;
@@ -32,6 +34,7 @@
  * @since 1.0
  */
 @GwtCompatible
+@ElementTypesAreNonnullByDefault
 public enum CaseFormat {
   /** Hyphenated variable naming convention, e.g., "lower-hyphen". */
   LOWER_HYPHEN(CharMatcher.is('-'), "-") {
@@ -135,11 +138,7 @@ public final String to(CaseFormat format, String str) {
    * j = wordBoundary.indexIn ensures that j is -1 or
    * j >= 0 && j < s.length()
    */
-  @SuppressWarnings({
-    "upperbound:assignment.type.incompatible", "upperbound:compound.assignment.type.incompatible", // refinement on multiple assignments in expression
-    "upperbound:argument.type.incompatible", // length of sequence with ArrayLenRange in offset
-    "upperbound:unary.increment.type.incompatible",
-  })
+  @SuppressWarnings("nullness:argument") // out is initialized when i == 0
   String convert(CaseFormat format, String s) {
     // deal with camel conversion
     StringBuilder out = null;
@@ -151,14 +150,14 @@ String convert(CaseFormat format, String s) {
         out = new StringBuilder(s.length() + 4 * format.wordSeparator.length());
         out.append(format.normalizeFirstWord(s.substring(i, j)));
       } else {
-        out.append(format.normalizeWord(s.substring(i, j)));
+        requireNonNull(out).append(format.normalizeWord(s.substring(i, j)));
       }
       out.append(format.wordSeparator);
       i = j + wordSeparator.length();
     }
     return (i == 0)
         ? format.normalizeFirstWord(s)
-        : out.append(format.normalizeWord(s.substring(i))).toString();
+        : requireNonNull(out).append(format.normalizeWord(s.substring(i))).toString();
   }
 
   /**
@@ -192,7 +191,7 @@ protected String doBackward(String s) {
     }
 
     @Override
-    public boolean equals(@Nullable Object object) {
+    public boolean equals(@CheckForNull Object object) {
       if (object instanceof StringConverter) {
         StringConverter that = (StringConverter) object;
         return sourceFormat.equals(that.sourceFormat) && targetFormat.equals(that.targetFormat);
diff --git a/guava/src/com/google/common/base/CharMatcher.java b/guava/src/com/google/common/base/CharMatcher.java
index f1d509c29262..1dbdf5ea8403 100644
--- a/guava/src/com/google/common/base/CharMatcher.java
+++ b/guava/src/com/google/common/base/CharMatcher.java
@@ -68,6 +68,7 @@
  * @since 1.0
  */
 @GwtCompatible(emulated = true)
+@ElementTypesAreNonnullByDefault
 public abstract class CharMatcher implements Predicate<Character> {
   /*
    *           N777777777NO
@@ -1498,10 +1499,10 @@ private static final class Invisible extends RangesMatcher {
     // [[[:Zs:][:Zl:][:Zp:][:Cc:][:Cf:][:Cs:][:Co:]]&[\u0000-\uFFFF]]
     // with the "Abbreviate" option, and get the ranges from there.
     private static final String RANGE_STARTS =
-        "\u0000\u007f\u00ad\u0600\u061c\u06dd\u070f\u08e2\u1680\u180e\u2000\u2028\u205f\u2066"
+        "\u0000\u007f\u00ad\u0600\u061c\u06dd\u070f\u0890\u08e2\u1680\u180e\u2000\u2028\u205f\u2066"
             + "\u3000\ud800\ufeff\ufff9";
     private static final String RANGE_ENDS = // inclusive ends
-        "\u0020\u00a0\u00ad\u0605\u061c\u06dd\u070f\u08e2\u1680\u180e\u200f\u202f\u2064\u206f"
+        "\u0020\u00a0\u00ad\u0605\u061c\u06dd\u070f\u0891\u08e2\u1680\u180e\u200f\u202f\u2064\u206f"
             + "\u3000\uf8ff\ufeff\ufffb";
 
     static final Invisible INSTANCE = new Invisible();
@@ -1842,7 +1843,7 @@ public boolean matches(char c) {
     }
 
     @Override
-    @SuppressWarnings("signedness:type.argument")
+    @SuppressWarnings("signature.argument")
     public boolean apply(Character character) {
       return predicate.apply(checkNotNull(character));
     }
diff --git a/guava/src/com/google/common/base/Charsets.java b/guava/src/com/google/common/base/Charsets.java
index 2c9563d769c8..7aebea826c78 100644
--- a/guava/src/com/google/common/base/Charsets.java
+++ b/guava/src/com/google/common/base/Charsets.java
@@ -31,6 +31,7 @@
  * @since 1.0
  */
 @GwtCompatible(emulated = true)
+@ElementTypesAreNonnullByDefault
 public final class Charsets {
   private Charsets() {}
 
diff --git a/guava/src/com/google/common/base/CommonMatcher.java b/guava/src/com/google/common/base/CommonMatcher.java
index 4c0cefeff7fa..a5483645bc91 100644
--- a/guava/src/com/google/common/base/CommonMatcher.java
+++ b/guava/src/com/google/common/base/CommonMatcher.java
@@ -23,6 +23,7 @@
  * javadoc for details.
  */
 @GwtCompatible
+@ElementTypesAreNonnullByDefault
 abstract class CommonMatcher {
   public abstract boolean matches();
 
diff --git a/guava/src/com/google/common/base/CommonPattern.java b/guava/src/com/google/common/base/CommonPattern.java
index ce287213fc64..734ebae4696b 100644
--- a/guava/src/com/google/common/base/CommonPattern.java
+++ b/guava/src/com/google/common/base/CommonPattern.java
@@ -25,6 +25,7 @@
  */
 @AnnotatedFor({"nullness"})
 @GwtCompatible
+@ElementTypesAreNonnullByDefault
 abstract class CommonPattern {
   public abstract CommonMatcher matcher(CharSequence t);
 
diff --git a/guava/src/com/google/common/base/Converter.java b/guava/src/com/google/common/base/Converter.java
index 623a206dc797..6c16bcaf5934 100644
--- a/guava/src/com/google/common/base/Converter.java
+++ b/guava/src/com/google/common/base/Converter.java
@@ -14,15 +14,19 @@
 
 package com.google.common.base;
 
+import static com.google.common.base.NullnessCasts.uncheckedCastNullableTToT;
 import static com.google.common.base.Preconditions.checkNotNull;
 
 import com.google.common.annotations.GwtCompatible;
 import com.google.errorprone.annotations.CanIgnoreReturnValue;
+import com.google.errorprone.annotations.CheckReturnValue;
 import com.google.errorprone.annotations.ForOverride;
+import com.google.errorprone.annotations.InlineMe;
 import com.google.errorprone.annotations.concurrent.LazyInit;
 import com.google.j2objc.annotations.RetainedWith;
 import java.io.Serializable;
 import java.util.Iterator;
+import javax.annotation.CheckForNull;
 import org.checkerframework.checker.nullness.qual.Nullable;
 import org.checkerframework.checker.nullness.qual.PolyNull;
 
@@ -114,11 +118,36 @@
  * @since 16.0
  */
 @GwtCompatible
+@ElementTypesAreNonnullByDefault
+/*
+ * 1. The type parameter is <T> rather than <T extends @Nullable> so that we can use T in the
+ * doForward and doBackward methods to indicate that the parameter cannot be null. (We also take
+ * advantage of that for convertAll, as discussed on that method.)
+ *
+ * 2. The supertype of this class could be `Function<@Nullable A, @Nullable B>`, since
+ * Converter.apply (like Converter.convert) is capable of accepting null inputs. However, a
+ * supertype of `Function<A, B>` turns out to be massively more useful to callers in practice: They
+ * want their output to be non-null in operations like `stream.map(myConverter)`, and we can
+ * guarantee that as long as we also require the input type to be non-null[*] (which is a
+ * requirement that existing callers already fulfill).
+ *
+ * Disclaimer: Part of the reason that callers are so well adapted to `Function<A, B>` may be that
+ * that is how the signature looked even prior to this comment! So naturally any change can break
+ * existing users, but it can't *fix* existing users because any users who needed
+ * `Function<@Nullable A, @Nullable B>` already had to find a workaround. Still, there is a *ton* of
+ * fallout from trying to switch. I would be shocked if the switch would offer benefits to anywhere
+ * near enough users to justify the costs.
+ *
+ * Fortunately, if anyone does want to use a Converter as a `Function<@Nullable A, @Nullable B>`,
+ * it's easy to get one: `converter::convert`.
+ *
+ * [*] In annotating this class, we're ignoring LegacyConverter.
+ */
 public abstract class Converter<A, B> implements Function<A, B> {
   private final boolean handleNullAutomatically;
 
   // We lazily cache the reverse view to avoid allocating on every call to reverse().
-  @LazyInit @RetainedWith private transient @Nullable Converter<B, A> reverse;
+  @LazyInit @RetainedWith @CheckForNull private transient Converter<B, A> reverse;
 
   /** Constructor for use by subclasses. */
   protected Converter() {
@@ -165,30 +194,67 @@ protected Converter() {
    * @return the converted value; is null <i>if and only if</i> {@code a} is null
    */
   @CanIgnoreReturnValue
-  public final @PolyNull B convert(@PolyNull A a) {
+  @CheckForNull
+  public final B convert(@CheckForNull A a) {
     return correctedDoForward(a);
   }
 
-  @Nullable
-  B correctedDoForward(@Nullable A a) {
+  @CheckForNull
+  B correctedDoForward(@CheckForNull A a) {
     if (handleNullAutomatically) {
       // TODO(kevinb): we shouldn't be checking for a null result at runtime. Assert?
       return a == null ? null : checkNotNull(doForward(a));
     } else {
-      return doForward(a);
+      return unsafeDoForward(a);
     }
   }
 
-  @Nullable
-  A correctedDoBackward(@Nullable B b) {
+  @CheckForNull
+  A correctedDoBackward(@CheckForNull B b) {
     if (handleNullAutomatically) {
       // TODO(kevinb): we shouldn't be checking for a null result at runtime. Assert?
       return b == null ? null : checkNotNull(doBackward(b));
     } else {
-      return doBackward(b);
+      return unsafeDoBackward(b);
     }
   }
 
+  /*
+   * LegacyConverter violates the contract of Converter by allowing its doForward and doBackward
+   * methods to accept null. We could avoid having unchecked casts in Converter.java itself if we
+   * could perform a cast to LegacyConverter, but we can't because it's an internal-only class.
+   *
+   * TODO(cpovirk): So make it part of the open-source build, albeit package-private there?
+   *
+   * So we use uncheckedCastNullableTToT here. This is a weird usage of that method: The method is
+   * documented as being for use with type parameters that have parametric nullness. But Converter's
+   * type parameters do not. Still, we use it here so that we can suppress a warning at a smaller
+   * level than the whole method but without performing a runtime null check. That way, we can still
+   * pass null inputs to LegacyConverter, and it can violate the contract of Converter.
+   *
+   * TODO(cpovirk): Could this be simplified if we modified implementations of LegacyConverter to
+   * override methods (probably called "unsafeDoForward" and "unsafeDoBackward") with the same
+   * signatures as the methods below, rather than overriding the same doForward and doBackward
+   * methods as implementations of normal converters do?
+   *
+   * But no matter what we do, it's worth remembering that the resulting code is going to be unsound
+   * in the presence of LegacyConverter, at least in the case of users who view the converter as a
+   * Function<A, B> or who call convertAll (and for any checkers that apply @PolyNull-like semantics
+   * to Converter.convert). So maybe we don't want to think too hard about how to prevent our
+   * checkers from issuing errors related to LegacyConverter, since it turns out that
+   * LegacyConverter does violate the assumptions we make elsewhere.
+   */
+
+  @CheckForNull
+  private B unsafeDoForward(@CheckForNull A a) {
+    return doForward(uncheckedCastNullableTToT(a));
+  }
+
+  @CheckForNull
+  private A unsafeDoBackward(@CheckForNull B b) {
+    return doBackward(uncheckedCastNullableTToT(b));
+  }
+
   /**
    * Returns an iterable that applies {@code convert} to each element of {@code fromIterable}. The
    * conversion is done lazily.
@@ -198,7 +264,17 @@ A correctedDoBackward(@Nullable B b) {
    * element.
    */
   @CanIgnoreReturnValue
-  public Iterable<B> convertAll(final Iterable<? extends A> fromIterable) {
+  /*
+   * Just as Converter could implement `Function<@Nullable A, @Nullable B>` instead of `Function<A,
+   * B>`, convertAll could accept and return iterables with nullable element types. In both cases,
+   * we've chosen to instead use a signature that benefits existing users -- and is still safe.
+   *
+   * For convertAll, I haven't looked as closely at *how* much existing users benefit, so we should
+   * keep an eye out for problems that new users encounter. Note also that convertAll could support
+   * both use cases by using @PolyNull. (By contrast, we can't use @PolyNull for our superinterface
+   * (`implements Function<@PolyNull A, @PolyNull B>`), at least as far as I know.)
+   */
+  public Iterable<B> convertAll(Iterable<? extends A> fromIterable) {
     checkNotNull(fromIterable, "fromIterable");
     return new Iterable<B>() {
       @Override
@@ -212,6 +288,8 @@ public boolean hasNext() {
           }
 
           @Override
+          @SuppressWarnings("nullness") // See code comments on convertAll and Converter.apply.
+          @CheckForNull
           public B next() {
             return convert(fromIterator.next());
           }
@@ -233,7 +311,7 @@ public void remove() {
    *
    * <p><b>Note:</b> you should not override this method. It is non-final for legacy reasons.
    */
-  @CanIgnoreReturnValue
+  @CheckReturnValue
   public Converter<B, A> reverse() {
     Converter<B, A> result = reverse;
     return (result == null) ? reverse = new ReverseConverter<>(this) : result;
@@ -265,14 +343,14 @@ protected B doBackward(A a) {
     }
 
     @Override
-    @Nullable
-    A correctedDoForward(@Nullable B b) {
+    @CheckForNull
+    A correctedDoForward(@CheckForNull B b) {
       return original.correctedDoBackward(b);
     }
 
     @Override
-    @Nullable
-    B correctedDoBackward(@Nullable A a) {
+    @CheckForNull
+    B correctedDoBackward(@CheckForNull A a) {
       return original.correctedDoForward(a);
     }
 
@@ -282,7 +360,7 @@ public Converter<A, B> reverse() {
     }
 
     @Override
-    public boolean equals(@Nullable Object object) {
+    public boolean equals(@CheckForNull Object object) {
       if (object instanceof ReverseConverter) {
         ReverseConverter<?, ?> that = (ReverseConverter<?, ?>) object;
         return this.original.equals(that.original);
@@ -347,19 +425,19 @@ protected A doBackward(C c) {
     }
 
     @Override
-    @Nullable
-    C correctedDoForward(@Nullable A a) {
+    @CheckForNull
+    C correctedDoForward(@CheckForNull A a) {
       return second.correctedDoForward(first.correctedDoForward(a));
     }
 
     @Override
-    @Nullable
-    A correctedDoBackward(@Nullable C c) {
+    @CheckForNull
+    A correctedDoBackward(@CheckForNull C c) {
       return first.correctedDoBackward(second.correctedDoBackward(c));
     }
 
     @Override
-    public boolean equals(@Nullable Object object) {
+    public boolean equals(@CheckForNull Object object) {
       if (object instanceof ConverterComposition) {
         ConverterComposition<?, ?, ?> that = (ConverterComposition<?, ?, ?>) object;
         return this.first.equals(that.first) && this.second.equals(that.second);
@@ -386,7 +464,40 @@ public String toString() {
   @Deprecated
   @Override
   @CanIgnoreReturnValue
-  public final @Nullable B apply(@Nullable A a) {
+  /*
+   * Even though we implement `Function<A, B>` instead of `Function<@Nullable A, @Nullable B>` (as
+   * discussed in a code comment at the top of the class), we declare our override of Function.apply
+   * to accept and return null. This requires a suppression, but it's safe:
+   *
+   * - Callers who use Converter as a Function<A, B> will neither pass null nor have it returned to
+   *   them. (Or, if they're not using nullness checking, they might be able to pass null and thus
+   *   have null returned to them. But our signature isn't making their existing nullness type error
+   *   any worse.)
+   * - In the relatively unlikely event that anyone calls Converter.apply directly, that caller is
+   *   allowed to pass null but is also forced to deal with a potentially null return.
+   * - Perhaps more important than actual *callers* of this method are various tools that look at
+   *   bytecode. Notably, NullPointerTester expects a method to throw NPE when passed null unless it
+   *   is annotated in a way that identifies its parameter type as potentially including null. (And
+   *   this method does not throw NPE -- nor do we want to enact a dangerous change to make it begin
+   *   doing so.) We can even imagine tools that rewrite bytecode to insert null checks before and
+   *   after calling methods with allegedly non-nullable parameters[*]. If we didn't annotate the
+   *   parameter and return type here, then anyone who used such a tool (and managed to pass null to
+   *   this method, presumably because that user doesn't run a normal nullness checker) could see
+   *   NullPointerException.
+   *
+   * [*] Granted, such tools could conceivably be smart enough to recognize that the apply() method
+   * on a a Function<Foo, Bar> should never allow null inputs and never produce null outputs even if
+   * this specific subclass claims otherwise. Such tools might still produce NPE for calls to this
+   * method. And that is one reason that we should be nervous about "lying" by extending Function<A,
+   * B> in the first place. But for now, we're giving it a try, since extending Function<@Nullable
+   * A, @Nullable B> will cause issues *today*, whereas extending Function<A, B> causes problems in
+   * various hypothetical futures. (Plus, a tool that were that smart would likely already introduce
+   * problems with LegacyConverter.)
+   */
+  @SuppressWarnings("nullness")
+  @CheckForNull
+  @InlineMe(replacement = "this.convert(a)")
+  public final B apply(@CheckForNull A a) {
     return convert(a);
   }
 
@@ -402,7 +513,7 @@ public String toString() {
    * interchangeable.
    */
   @Override
-  public boolean equals(@Nullable Object object) {
+  public boolean equals(@CheckForNull Object object) {
     return super.equals(object);
   }
 
@@ -451,7 +562,7 @@ protected A doBackward(B b) {
     }
 
     @Override
-    public boolean equals(@Nullable Object object) {
+    public boolean equals(@CheckForNull Object object) {
       if (object instanceof FunctionBasedConverter) {
         FunctionBasedConverter<?, ?> that = (FunctionBasedConverter<?, ?>) object;
         return this.forwardFunction.equals(that.forwardFunction)
diff --git a/guava/src/com/google/common/base/Defaults.java b/guava/src/com/google/common/base/Defaults.java
index 92958c15c7d4..5d12343ed241 100644
--- a/guava/src/com/google/common/base/Defaults.java
+++ b/guava/src/com/google/common/base/Defaults.java
@@ -17,7 +17,7 @@
 import static com.google.common.base.Preconditions.checkNotNull;
 
 import com.google.common.annotations.GwtIncompatible;
-import org.checkerframework.checker.nullness.qual.Nullable;
+import javax.annotation.CheckForNull;
 
 /**
  * This class provides default values for all Java types, as defined by the JLS.
@@ -26,11 +26,12 @@
  * @since 1.0
  */
 @GwtIncompatible
+@ElementTypesAreNonnullByDefault
 public final class Defaults {
   private Defaults() {}
 
-  private static final Double DOUBLE_DEFAULT = Double.valueOf(0d);
-  private static final Float FLOAT_DEFAULT = Float.valueOf(0f);
+  private static final Double DOUBLE_DEFAULT = 0d;
+  private static final Float FLOAT_DEFAULT = 0f;
 
   /**
    * Returns the default value of {@code type} as defined by JLS --- {@code 0} for numbers, {@code
@@ -38,26 +39,28 @@ private Defaults() {}
    * {@code void}, {@code null} is returned.
    */
   @SuppressWarnings("unchecked")
-  public static <T> @Nullable T defaultValue(Class<T> type) {
+  @CheckForNull
+  public static <T> T defaultValue(Class<T> type) {
     checkNotNull(type);
-    if (type == boolean.class) {
-      return (T) Boolean.FALSE;
-    } else if (type == char.class) {
-      return (T) Character.valueOf('\0');
-    } else if (type == byte.class) {
-      return (T) Byte.valueOf((byte) 0);
-    } else if (type == short.class) {
-      return (T) Short.valueOf((short) 0);
-    } else if (type == int.class) {
-      return (T) Integer.valueOf(0);
-    } else if (type == long.class) {
-      return (T) Long.valueOf(0L);
-    } else if (type == float.class) {
-      return (T) FLOAT_DEFAULT;
-    } else if (type == double.class) {
-      return (T) DOUBLE_DEFAULT;
-    } else {
-      return null;
+    if (type.isPrimitive()) {
+      if (type == boolean.class) {
+        return (T) Boolean.FALSE;
+      } else if (type == char.class) {
+        return (T) Character.valueOf('\0');
+      } else if (type == byte.class) {
+        return (T) Byte.valueOf((byte) 0);
+      } else if (type == short.class) {
+        return (T) Short.valueOf((short) 0);
+      } else if (type == int.class) {
+        return (T) Integer.valueOf(0);
+      } else if (type == long.class) {
+        return (T) Long.valueOf(0L);
+      } else if (type == float.class) {
+        return (T) FLOAT_DEFAULT;
+      } else if (type == double.class) {
+        return (T) DOUBLE_DEFAULT;
+      }
     }
+    return null;
   }
 }
diff --git a/guava/src/com/google/common/base/ElementTypesAreNonnullByDefault.java b/guava/src/com/google/common/base/ElementTypesAreNonnullByDefault.java
new file mode 100644
index 000000000000..890e3a36062a
--- /dev/null
+++ b/guava/src/com/google/common/base/ElementTypesAreNonnullByDefault.java
@@ -0,0 +1,41 @@
+/*
+ * Copyright (C) 2021 The Guava Authors
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package com.google.common.base;
+
+import static java.lang.annotation.ElementType.FIELD;
+import static java.lang.annotation.ElementType.METHOD;
+import static java.lang.annotation.ElementType.PARAMETER;
+import static java.lang.annotation.ElementType.TYPE;
+import static java.lang.annotation.RetentionPolicy.RUNTIME;
+
+import com.google.common.annotations.GwtCompatible;
+import java.lang.annotation.Retention;
+import java.lang.annotation.Target;
+import javax.annotation.Nonnull;
+import javax.annotation.meta.TypeQualifierDefault;
+
+/**
+ * Marks all "top-level" types as non-null in a way that is recognized by Kotlin. Note that this
+ * unfortunately includes type-variable usages, so we also provide {@link ParametricNullness} to
+ * "undo" it as best we can.
+ */
+@GwtCompatible
+@Retention(RUNTIME)
+@Target(TYPE)
+@TypeQualifierDefault({FIELD, METHOD, PARAMETER})
+@Nonnull
+@interface ElementTypesAreNonnullByDefault {}
diff --git a/guava/src/com/google/common/base/Enums.java b/guava/src/com/google/common/base/Enums.java
index b8d2401effc7..16359ce5028d 100644
--- a/guava/src/com/google/common/base/Enums.java
+++ b/guava/src/com/google/common/base/Enums.java
@@ -25,6 +25,7 @@
 import java.util.HashMap;
 import java.util.Map;
 import java.util.WeakHashMap;
+import javax.annotation.CheckForNull;
 import org.checkerframework.checker.nullness.qual.Nullable;
 import org.checkerframework.framework.qual.AnnotatedFor;
 
@@ -36,6 +37,7 @@
  */
 @AnnotatedFor({"nullness"})
 @GwtCompatible(emulated = true)
+@ElementTypesAreNonnullByDefault
 public final class Enums {
 
   private Enums() {}
@@ -106,8 +108,8 @@ static <T extends Enum<T>> Map<String, WeakReference<? extends Enum<?>>> getEnum
    *
    * @since 16.0
    */
-  public static <T extends Enum<T>> Converter<String, T> stringConverter(final Class<T> enumClass) {
-    return new StringConverter<T>(enumClass);
+  public static <T extends Enum<T>> Converter<String, T> stringConverter(Class<T> enumClass) {
+    return new StringConverter<>(enumClass);
   }
 
   private static final class StringConverter<T extends Enum<T>> extends Converter<String, T>
@@ -130,7 +132,7 @@ protected String doBackward(T enumValue) {
     }
 
     @Override
-    public boolean equals(@Nullable Object object) {
+    public boolean equals(@CheckForNull Object object) {
       if (object instanceof StringConverter) {
         StringConverter<?> that = (StringConverter<?>) object;
         return this.enumClass.equals(that.enumClass);
diff --git a/guava/src/com/google/common/base/Equivalence.java b/guava/src/com/google/common/base/Equivalence.java
index b4ac005708af..4e2e89886a2a 100644
--- a/guava/src/com/google/common/base/Equivalence.java
+++ b/guava/src/com/google/common/base/Equivalence.java
@@ -20,6 +20,7 @@
 import com.google.errorprone.annotations.ForOverride;
 import java.io.Serializable;
 import java.util.function.BiPredicate;
+import javax.annotation.CheckForNull;
 import org.checkerframework.checker.nullness.qual.Nullable;
 
 /**
@@ -34,7 +35,12 @@
  *     source-compatible</a> since 4.0)
  */
 @GwtCompatible
-public abstract class Equivalence<T> implements BiPredicate<T, T> {
+@ElementTypesAreNonnullByDefault
+/*
+ * The type parameter is <T> rather than <T extends @Nullable> so that we can use T in the
+ * doEquivalent and doHash methods to indicate that the parameter cannot be null.
+ */
+public abstract class Equivalence<T> implements BiPredicate<@Nullable T, @Nullable T> {
   /** Constructor for use by subclasses. */
   protected Equivalence() {}
 
@@ -55,7 +61,7 @@ protected Equivalence() {}
    * <p>Note that all calls to {@code equivalent(x, y)} are expected to return the same result as
    * long as neither {@code x} nor {@code y} is modified.
    */
-  public final boolean equivalent(@Nullable T a, @Nullable T b) {
+  public final boolean equivalent(@CheckForNull T a, @CheckForNull T b) {
     if (a == b) {
       return true;
     }
@@ -72,7 +78,7 @@ public final boolean equivalent(@Nullable T a, @Nullable T b) {
    */
   @Deprecated
   @Override
-  public final boolean test(@Nullable T t, @Nullable T u) {
+  public final boolean test(@CheckForNull T t, @CheckForNull T u) {
     return equivalent(t, u);
   }
 
@@ -105,7 +111,7 @@ public final boolean test(@Nullable T t, @Nullable T u) {
    *   <li>{@code hash(null)} is {@code 0}.
    * </ul>
    */
-  public final int hash(@Nullable T t) {
+  public final int hash(@CheckForNull T t) {
     if (t == null) {
       return 0;
     }
@@ -147,7 +153,7 @@ public final int hash(@Nullable T t) {
    *
    * @since 10.0
    */
-  public final <F> Equivalence<F> onResultOf(Function<F, ? extends T> function) {
+  public final <F> Equivalence<F> onResultOf(Function<? super F, ? extends @Nullable T> function) {
     return new FunctionalEquivalence<>(function, this);
   }
 
@@ -158,8 +164,44 @@ public final <F> Equivalence<F> onResultOf(Function<F, ? extends T> function) {
    *
    * @since 10.0
    */
-  public final <S extends T> Wrapper<S> wrap(@Nullable S reference) {
-    return new Wrapper<S>(this, reference);
+  public final <S extends @Nullable T> Wrapper<S> wrap(@ParametricNullness S reference) {
+    /*
+     * I'm pretty sure that this warning "makes sense" but doesn't indicate a real problem.
+     *
+     * Why it "makes sense": If we pass a `@Nullable Foo`, then we should also pass an
+     * `Equivalence<? super @Nullable Foo>`. And there's no such thing because Equivalence doesn't
+     * permit nullable type arguments.
+     *
+     * Why there's no real problem: Every Equivalence can handle null.
+     *
+     * We could work around this by giving Wrapper 2 type parameters. In the terms of this method,
+     * that would be both the T parameter (from the class) and the S parameter (from this method).
+     * However, such a change would be source-incompatible. (Plus, there's no reason for the S
+     * parameter from the user's perspective, so it would be a wart.)
+     *
+     * We could probably also work around this by making Wrapper non-final and putting the
+     * implementation into a subclass with those 2 type parameters. But we like `final`, if only to
+     * deter users from using mocking frameworks to construct instances. (And could also complicate
+     * serialization, which is discussed more in the next paragraph.)
+     *
+     * We could probably also work around this by having Wrapper accept an instance of a new
+     * WrapperGuts class, which would then be the class that would declare the 2 type parameters.
+     * But that would break deserialization of previously serialized Wrapper instances. And while we
+     * specifically say not to rely on serialization across Guava versions, users sometimes do. So
+     * we'd rather not break them without a good enough reason.
+     *
+     * (We could work around the serialization problem by writing custom serialization code. But
+     * even that helps only the case of serializing with an old version and deserializing with a
+     * new, not vice versa -- unless we introduce WrapperGuts and the logic to handle it today, wait
+     * until "everyone" has picked up a version of Guava with that code, and *then* change to use
+     * WrapperGuts.)
+     *
+     * Anyway, a suppression isn't really a big deal. But I have tried to do some due diligence on
+     * avoiding it :)
+     */
+    @SuppressWarnings("nullness")
+    Wrapper<S> w = new Wrapper<>(this, reference);
+    return w;
   }
 
   /**
@@ -182,17 +224,18 @@ public final <S extends T> Wrapper<S> wrap(@Nullable S reference) {
    *
    * @since 10.0
    */
-  public static final class Wrapper<T> implements Serializable {
+  public static final class Wrapper<T extends @Nullable Object> implements Serializable {
     private final Equivalence<? super T> equivalence;
-    private final @Nullable T reference;
+    @ParametricNullness private final T reference;
 
-    private Wrapper(Equivalence<? super T> equivalence, @Nullable T reference) {
+    private Wrapper(Equivalence<? super T> equivalence, @ParametricNullness T reference) {
       this.equivalence = checkNotNull(equivalence);
       this.reference = reference;
     }
 
     /** Returns the (possibly null) reference wrapped by this instance. */
-    public @Nullable T get() {
+    @ParametricNullness
+    public T get() {
       return reference;
     }
 
@@ -202,7 +245,7 @@ private Wrapper(Equivalence<? super T> equivalence, @Nullable T reference) {
      * equivalence.
      */
     @Override
-    public boolean equals(@Nullable Object obj) {
+    public boolean equals(@CheckForNull Object obj) {
       if (obj == this) {
         return true;
       }
@@ -252,10 +295,10 @@ public String toString() {
    * @since 10.0
    */
   @GwtCompatible(serializable = true)
-  public final <S extends T> Equivalence<Iterable<S>> pairwise() {
+  public final <S extends @Nullable T> Equivalence<Iterable<S>> pairwise() {
     // Ideally, the returned equivalence would support Iterable<? extends T>. However,
     // the need for this is so rare that it's not worth making callers deal with the ugly wildcard.
-    return new PairwiseEquivalence<S>(this);
+    return new PairwiseEquivalence<>(this);
   }
 
   /**
@@ -264,27 +307,28 @@ public final <S extends T> Equivalence<Iterable<S>> pairwise() {
    *
    * @since 10.0
    */
-  public final Predicate<T> equivalentTo(@Nullable T target) {
+  public final Predicate<@Nullable T> equivalentTo(@CheckForNull T target) {
     return new EquivalentToPredicate<T>(this, target);
   }
 
-  private static final class EquivalentToPredicate<T> implements Predicate<T>, Serializable {
+  private static final class EquivalentToPredicate<T>
+      implements Predicate<@Nullable T>, Serializable {
 
     private final Equivalence<T> equivalence;
-    private final @Nullable T target;
+    @CheckForNull private final T target;
 
-    EquivalentToPredicate(Equivalence<T> equivalence, @Nullable T target) {
+    EquivalentToPredicate(Equivalence<T> equivalence, @CheckForNull T target) {
       this.equivalence = checkNotNull(equivalence);
       this.target = target;
     }
 
     @Override
-    public boolean apply(@Nullable T input) {
+    public boolean apply(@CheckForNull T input) {
       return equivalence.equivalent(input, target);
     }
 
     @Override
-    public boolean equals(@Nullable Object obj) {
+    public boolean equals(@CheckForNull Object obj) {
       if (this == obj) {
         return true;
       }
diff --git a/guava/src/com/google/common/base/ExtraObjectsMethodsForWeb.java b/guava/src/com/google/common/base/ExtraObjectsMethodsForWeb.java
index 21cca2c109d6..677075522028 100644
--- a/guava/src/com/google/common/base/ExtraObjectsMethodsForWeb.java
+++ b/guava/src/com/google/common/base/ExtraObjectsMethodsForWeb.java
@@ -21,4 +21,5 @@
  * version.
  */
 @GwtCompatible(emulated = true)
+@ElementTypesAreNonnullByDefault
 abstract class ExtraObjectsMethodsForWeb {}
diff --git a/guava/src/com/google/common/base/FinalizablePhantomReference.java b/guava/src/com/google/common/base/FinalizablePhantomReference.java
index c15735323b9f..64c8cc6e0de9 100644
--- a/guava/src/com/google/common/base/FinalizablePhantomReference.java
+++ b/guava/src/com/google/common/base/FinalizablePhantomReference.java
@@ -17,6 +17,7 @@
 import com.google.common.annotations.GwtIncompatible;
 import java.lang.ref.PhantomReference;
 import java.lang.ref.ReferenceQueue;
+import javax.annotation.CheckForNull;
 import org.checkerframework.framework.qual.AnnotatedFor;
 
 /**
@@ -31,6 +32,7 @@
  */
 @AnnotatedFor({"nullness"})
 @GwtIncompatible
+@ElementTypesAreNonnullByDefault
 public abstract class FinalizablePhantomReference<T> extends PhantomReference<T>
     implements FinalizableReference {
   /**
@@ -39,7 +41,7 @@ public abstract class FinalizablePhantomReference<T> extends PhantomReference<T>
    * @param referent to phantom reference
    * @param queue that should finalize the referent
    */
-  protected FinalizablePhantomReference(T referent, FinalizableReferenceQueue queue) {
+  protected FinalizablePhantomReference(@CheckForNull T referent, FinalizableReferenceQueue queue) {
     super(referent, queue.queue);
     queue.cleanUp();
   }
diff --git a/guava/src/com/google/common/base/FinalizableReference.java b/guava/src/com/google/common/base/FinalizableReference.java
index e5e64f2b31ff..5fa4726bec42 100644
--- a/guava/src/com/google/common/base/FinalizableReference.java
+++ b/guava/src/com/google/common/base/FinalizableReference.java
@@ -29,6 +29,7 @@
 @AnnotatedFor({"nullness"})
 @DoNotMock("Use an instance of one of the Finalizable*Reference classes")
 @GwtIncompatible
+@ElementTypesAreNonnullByDefault
 public interface FinalizableReference {
   /**
    * Invoked on a background thread after the referent has been garbage collected unless security
diff --git a/guava/src/com/google/common/base/FinalizableReferenceQueue.java b/guava/src/com/google/common/base/FinalizableReferenceQueue.java
index d0e16b6e6b6e..7447b8051d31 100644
--- a/guava/src/com/google/common/base/FinalizableReferenceQueue.java
+++ b/guava/src/com/google/common/base/FinalizableReferenceQueue.java
@@ -27,7 +27,7 @@
 import java.net.URLClassLoader;
 import java.util.logging.Level;
 import java.util.logging.Logger;
-import org.checkerframework.checker.nullness.qual.Nullable;
+import javax.annotation.CheckForNull;
 
 /**
  * A reference queue with an associated background thread that dequeues references and invokes
@@ -37,7 +37,7 @@
  * finalized. If this object is garbage collected earlier, the backing thread will not invoke {@code
  * finalizeReferent()} on the remaining references.
  *
- * <p>As an example of how this is used, imagine you have a class {@code MyServer} that creates a a
+ * <p>As an example of how this is used, imagine you have a class {@code MyServer} that creates a
  * {@link java.net.ServerSocket ServerSocket}, and you would like to ensure that the {@code
  * ServerSocket} is closed even if the {@code MyServer} object is garbage-collected without calling
  * its {@code close} method. You <em>could</em> use a finalizer to accomplish this, but that has a
@@ -89,6 +89,7 @@
  * @since 2.0
  */
 @GwtIncompatible
+@ElementTypesAreNonnullByDefault
 public class FinalizableReferenceQueue implements Closeable {
   /*
    * The Finalizer thread keeps a phantom reference to this object. When the client (for example, a
@@ -155,7 +156,7 @@ public class FinalizableReferenceQueue implements Closeable {
   public FinalizableReferenceQueue() {
     // We could start the finalizer lazily, but I'd rather it blow up early.
     queue = new ReferenceQueue<>();
-    frqRef = new PhantomReference<Object>(this, queue);
+    frqRef = new PhantomReference<>(this, queue);
     boolean threadStarted = false;
     try {
       startFinalizer.invoke(null, FinalizableReference.class, queue, frqRef);
@@ -228,7 +229,7 @@ interface FinalizerLoader {
      *
      * @throws SecurityException if we don't have the appropriate privileges
      */
-    @Nullable
+    @CheckForNull
     Class<?> loadFinalizer();
   }
 
@@ -242,7 +243,8 @@ static class SystemLoader implements FinalizerLoader {
     @VisibleForTesting static boolean disabled;
 
     @Override
-    public @Nullable Class<?> loadFinalizer() {
+    @CheckForNull
+    public Class<?> loadFinalizer() {
       if (disabled) {
         return null;
       }
@@ -279,7 +281,8 @@ static class DecoupledLoader implements FinalizerLoader {
             + "issue, or move Guava to your system class path.";
 
     @Override
-    public @Nullable Class<?> loadFinalizer() {
+    @CheckForNull
+    public Class<?> loadFinalizer() {
       try {
         /*
          * We use URLClassLoader because it's the only concrete class loader implementation in the
@@ -299,7 +302,6 @@ static class DecoupledLoader implements FinalizerLoader {
     }
 
     /** Gets URL for base of path containing Finalizer.class. */
-    @SuppressWarnings("lowerbound:argument.type.incompatible") // https://github.com/kelloggm/checker-framework/issues/203
     URL getBaseUrl() throws IOException {
       // Find URL pointing to Finalizer.class file.
       String finalizerPath = FINALIZER_CLASS_NAME.replace('.', '/') + ".class";
diff --git a/guava/src/com/google/common/base/FinalizableSoftReference.java b/guava/src/com/google/common/base/FinalizableSoftReference.java
index ab7899a8e0aa..d4cb9e66a55a 100644
--- a/guava/src/com/google/common/base/FinalizableSoftReference.java
+++ b/guava/src/com/google/common/base/FinalizableSoftReference.java
@@ -17,6 +17,7 @@
 import com.google.common.annotations.GwtIncompatible;
 import java.lang.ref.ReferenceQueue;
 import java.lang.ref.SoftReference;
+import javax.annotation.CheckForNull;
 import org.checkerframework.framework.qual.AnnotatedFor;
 
 /**
@@ -29,6 +30,7 @@
  */
 @AnnotatedFor({"nullness"})
 @GwtIncompatible
+@ElementTypesAreNonnullByDefault
 public abstract class FinalizableSoftReference<T> extends SoftReference<T>
     implements FinalizableReference {
   /**
@@ -37,7 +39,7 @@ public abstract class FinalizableSoftReference<T> extends SoftReference<T>
    * @param referent to softly reference
    * @param queue that should finalize the referent
    */
-  protected FinalizableSoftReference(T referent, FinalizableReferenceQueue queue) {
+  protected FinalizableSoftReference(@CheckForNull T referent, FinalizableReferenceQueue queue) {
     super(referent, queue.queue);
     queue.cleanUp();
   }
diff --git a/guava/src/com/google/common/base/FinalizableWeakReference.java b/guava/src/com/google/common/base/FinalizableWeakReference.java
index 689ca10ca8aa..410fef53fd22 100644
--- a/guava/src/com/google/common/base/FinalizableWeakReference.java
+++ b/guava/src/com/google/common/base/FinalizableWeakReference.java
@@ -18,6 +18,7 @@
 import com.google.common.annotations.GwtIncompatible;
 import java.lang.ref.ReferenceQueue;
 import java.lang.ref.WeakReference;
+import javax.annotation.CheckForNull;
 
 /**
  * Weak reference with a {@code finalizeReferent()} method which a background thread invokes after
@@ -28,6 +29,7 @@
  * @since 2.0
  */
 @GwtIncompatible
+@ElementTypesAreNonnullByDefault
 public abstract class FinalizableWeakReference<T> extends WeakReference<T>
     implements FinalizableReference {
   /**
@@ -36,7 +38,7 @@ public abstract class FinalizableWeakReference<T> extends WeakReference<T>
    * @param referent to weakly reference
    * @param queue that should finalize the referent
    */
-  protected FinalizableWeakReference(T referent, FinalizableReferenceQueue queue) {
+  protected FinalizableWeakReference(@CheckForNull T referent, FinalizableReferenceQueue queue) {
     super(referent, queue.queue);
     queue.cleanUp();
   }
diff --git a/guava/src/com/google/common/base/Function.java b/guava/src/com/google/common/base/Function.java
index 864e97a7cc45..caa74141215e 100644
--- a/guava/src/com/google/common/base/Function.java
+++ b/guava/src/com/google/common/base/Function.java
@@ -16,6 +16,7 @@
 
 import com.google.common.annotations.GwtCompatible;
 import com.google.errorprone.annotations.CanIgnoreReturnValue;
+import javax.annotation.CheckForNull;
 import org.checkerframework.checker.nullness.qual.Nullable;
 import org.checkerframework.dataflow.qual.Pure;
 import org.checkerframework.framework.qual.AnnotatedFor;
@@ -44,11 +45,13 @@
 @GwtCompatible
 @AnnotatedFor({"nullness"})
 @FunctionalInterface
-public interface Function<F, T> extends java.util.function.Function<F, T> {
+@ElementTypesAreNonnullByDefault
+public interface Function<F extends @Nullable Object, T extends @Nullable Object>
+    extends java.util.function.Function<F, T> {
   @Override
   @CanIgnoreReturnValue // TODO(kevinb): remove this
-  @Nullable
-  T apply(@Nullable F input);
+  @ParametricNullness
+  T apply(@ParametricNullness F input);
 
   /**
    * <i>May</i> return {@code true} if {@code object} is a {@code Function} that behaves identically
@@ -63,5 +66,5 @@ public interface Function<F, T> extends java.util.function.Function<F, T> {
    */
   @Pure
   @Override
-  boolean equals(@Nullable Object object);
+  boolean equals(@CheckForNull Object object);
 }
diff --git a/guava/src/com/google/common/base/FunctionalEquivalence.java b/guava/src/com/google/common/base/FunctionalEquivalence.java
index 05b6271b16c0..4383f4f36c1a 100644
--- a/guava/src/com/google/common/base/FunctionalEquivalence.java
+++ b/guava/src/com/google/common/base/FunctionalEquivalence.java
@@ -19,6 +19,7 @@
 import com.google.common.annotations.Beta;
 import com.google.common.annotations.GwtCompatible;
 import java.io.Serializable;
+import javax.annotation.CheckForNull;
 import org.checkerframework.checker.nullness.qual.Nullable;
 
 /**
@@ -29,14 +30,16 @@
  */
 @Beta
 @GwtCompatible
+@ElementTypesAreNonnullByDefault
 final class FunctionalEquivalence<F, T> extends Equivalence<F> implements Serializable {
 
   private static final long serialVersionUID = 0;
 
-  private final Function<F, ? extends T> function;
+  private final Function<? super F, ? extends @Nullable T> function;
   private final Equivalence<T> resultEquivalence;
 
-  FunctionalEquivalence(Function<F, ? extends T> function, Equivalence<T> resultEquivalence) {
+  FunctionalEquivalence(
+      Function<? super F, ? extends @Nullable T> function, Equivalence<T> resultEquivalence) {
     this.function = checkNotNull(function);
     this.resultEquivalence = checkNotNull(resultEquivalence);
   }
@@ -52,7 +55,7 @@ protected int doHash(F a) {
   }
 
   @Override
-  public boolean equals(@Nullable Object obj) {
+  public boolean equals(@CheckForNull Object obj) {
     if (obj == this) {
       return true;
     }
diff --git a/guava/src/com/google/common/base/Functions.java b/guava/src/com/google/common/base/Functions.java
index 294af8ccfcb7..6797932b150a 100644
--- a/guava/src/com/google/common/base/Functions.java
+++ b/guava/src/com/google/common/base/Functions.java
@@ -14,12 +14,14 @@
 
 package com.google.common.base;
 
+import static com.google.common.base.NullnessCasts.uncheckedCastNullableTToT;
 import static com.google.common.base.Preconditions.checkArgument;
 import static com.google.common.base.Preconditions.checkNotNull;
 
 import com.google.common.annotations.GwtCompatible;
 import java.io.Serializable;
 import java.util.Map;
+import javax.annotation.CheckForNull;
 import org.checkerframework.checker.nullness.qual.Nullable;
 import org.checkerframework.dataflow.qual.Pure;
 import org.checkerframework.framework.qual.AnnotatedFor;
@@ -39,6 +41,7 @@
  */
 @AnnotatedFor({"nullness"})
 @GwtCompatible
+@ElementTypesAreNonnullByDefault
 public final class Functions {
   private Functions() {}
 
@@ -83,7 +86,7 @@ public String toString() {
   /** Returns the identity function. */
   // implementation is "fully variant"; E has become a "pass-through" type
   @SuppressWarnings("unchecked")
-  public static <E> Function<E, E> identity() {
+  public static <E extends @Nullable Object> Function<E, E> identity() {
     return (Function<E, E>) IdentityFunction.INSTANCE;
   }
 
@@ -92,7 +95,8 @@ private enum IdentityFunction implements Function<@Nullable Object, @Nullable Ob
     INSTANCE;
 
     @Override
-    public @Nullable Object apply(@Nullable Object o) {
+    @CheckForNull
+    public Object apply(@CheckForNull Object o) {
       return o;
     }
 
@@ -116,7 +120,8 @@ public String toString() {
    * key (instead of an exception being thrown), you can use the method reference {@code map::get}
    * instead.
    */
-  public static <K, V> Function<K, V> forMap(Map<K, V> map) {
+  public static <K extends @Nullable Object, V extends @Nullable Object> Function<K, V> forMap(
+      Map<K, V> map) {
     return new FunctionForMapNoDefault<>(map);
   }
 
@@ -133,11 +138,14 @@ public static <K, V> Function<K, V> forMap(Map<K, V> map) {
    * @return function that returns {@code map.get(a)} when {@code a} is a key, or {@code
    *     defaultValue} otherwise
    */
-  public static <K, V> Function<K, V> forMap(Map<K, ? extends V> map, @Nullable V defaultValue) {
+  public static <K extends @Nullable Object, V extends @Nullable Object> Function<K, V> forMap(
+      Map<K, ? extends V> map, @ParametricNullness V defaultValue) {
     return new ForMapWithDefault<>(map, defaultValue);
   }
 
-  private static class FunctionForMapNoDefault<K, V> implements Function<K, V>, Serializable {
+  private static class FunctionForMapNoDefault<
+          K extends @Nullable Object, V extends @Nullable Object>
+      implements Function<K, V>, Serializable {
     final Map<K, V> map;
 
     FunctionForMapNoDefault(Map<K, V> map) {
@@ -145,15 +153,17 @@ private static class FunctionForMapNoDefault<K, V> implements Function<K, V>, Se
     }
 
     @Override
-    public @Nullable V apply(@Nullable K key) {
-      @Nullable V result = map.get(key);
+    @ParametricNullness
+    public V apply(@ParametricNullness K key) {
+      V result = map.get(key);
       checkArgument(result != null || map.containsKey(key), "Key '%s' not present in map", key);
-      return result;
+      // The unchecked cast is safe because of the containsKey check.
+      return uncheckedCastNullableTToT(result);
     }
 
     @Pure
     @Override
-    public boolean equals(@Nullable Object o) {
+    public boolean equals(@CheckForNull Object o) {
       if (o instanceof FunctionForMapNoDefault) {
         FunctionForMapNoDefault<?, ?> that = (FunctionForMapNoDefault<?, ?>) o;
         return map.equals(that.map);
@@ -176,24 +186,29 @@ public String toString() {
     private static final long serialVersionUID = 0;
   }
 
-  private static class ForMapWithDefault<K, V> implements Function<K, V>, Serializable {
+  private static class ForMapWithDefault<K extends @Nullable Object, V extends @Nullable Object>
+      implements Function<K, V>, Serializable {
     final Map<K, ? extends V> map;
-    final @Nullable V defaultValue;
+    @ParametricNullness final V defaultValue;
 
-    ForMapWithDefault(Map<K, ? extends V> map, @Nullable V defaultValue) {
+    ForMapWithDefault(Map<K, ? extends V> map, @ParametricNullness V defaultValue) {
       this.map = checkNotNull(map);
       this.defaultValue = defaultValue;
     }
 
     @Override
-    public V apply(@Nullable K key) {
+    @ParametricNullness
+    public V apply(@ParametricNullness K key) {
       V result = map.get(key);
-      return (result != null || map.containsKey(key)) ? result : defaultValue;
+      // The unchecked cast is safe because of the containsKey check.
+      return (result != null || map.containsKey(key))
+          ? uncheckedCastNullableTToT(result)
+          : defaultValue;
     }
 
     @Pure
     @Override
-    public boolean equals(@Nullable Object o) {
+    public boolean equals(@CheckForNull Object o) {
       if (o instanceof ForMapWithDefault) {
         ForMapWithDefault<?, ?> that = (ForMapWithDefault<?, ?>) o;
         return map.equals(that.map) && Objects.equal(defaultValue, that.defaultValue);
@@ -229,11 +244,14 @@ public String toString() {
    * @return the composition of {@code f} and {@code g}
    * @see <a href="//en.wikipedia.org/wiki/Function_composition">function composition</a>
    */
-  public static <A, B, C> Function<A, C> compose(Function<B, C> g, Function<A, ? extends B> f) {
+  public static <A extends @Nullable Object, B extends @Nullable Object, C extends @Nullable Object>
+      Function<A, C> compose(Function<B, C> g, Function<A, ? extends B> f) {
     return new FunctionComposition<>(g, f);
   }
 
-  private static class FunctionComposition<A, B, C> implements Function<A, C>, Serializable {
+  private static class FunctionComposition<
+          A extends @Nullable Object, B extends @Nullable Object, C extends @Nullable Object>
+      implements Function<A, C>, Serializable {
     private final Function<B, C> g;
     private final Function<A, ? extends B> f;
 
@@ -243,13 +261,14 @@ public FunctionComposition(Function<B, C> g, Function<A, ? extends B> f) {
     }
 
     @Override
-    public C apply(@Nullable A a) {
+    @ParametricNullness
+    public C apply(@ParametricNullness A a) {
       return g.apply(f.apply(a));
     }
 
     @Pure
     @Override
-    public boolean equals(@Nullable Object obj) {
+    public boolean equals(@CheckForNull Object obj) {
       if (obj instanceof FunctionComposition) {
         FunctionComposition<?, ?, ?> that = (FunctionComposition<?, ?, ?>) obj;
         return f.equals(that.f) && g.equals(that.g);
@@ -281,12 +300,14 @@ public String toString() {
    *
    * <p><b>Java 8 users:</b> use the method reference {@code predicate::test} instead.
    */
-  public static <T> Function<T, Boolean> forPredicate(Predicate<T> predicate) {
-    return new PredicateFunction<T>(predicate);
+  public static <T extends @Nullable Object> Function<T, Boolean> forPredicate(
+      Predicate<T> predicate) {
+    return new PredicateFunction<>(predicate);
   }
 
   /** @see Functions#forPredicate */
-  private static class PredicateFunction<T> implements Function<T, Boolean>, Serializable {
+  private static class PredicateFunction<T extends @Nullable Object>
+      implements Function<T, Boolean>, Serializable {
     private final Predicate<T> predicate;
 
     private PredicateFunction(Predicate<T> predicate) {
@@ -294,13 +315,13 @@ private PredicateFunction(Predicate<T> predicate) {
     }
 
     @Override
-    public Boolean apply(@Nullable T t) {
+    public Boolean apply(@ParametricNullness T t) {
       return predicate.apply(t);
     }
 
     @Pure
     @Override
-    public boolean equals(@Nullable Object obj) {
+    public boolean equals(@CheckForNull Object obj) {
       if (obj instanceof PredicateFunction) {
         PredicateFunction<?> that = (PredicateFunction<?>) obj;
         return predicate.equals(that.predicate);
@@ -331,25 +352,28 @@ public String toString() {
    * @param value the constant value for the function to return
    * @return a function that always returns {@code value}
    */
-  public static <E> Function<Object, E> constant(@Nullable E value) {
-    return new ConstantFunction<E>(value);
+  public static <E extends @Nullable Object> Function<@Nullable Object, E> constant(
+      @ParametricNullness E value) {
+    return new ConstantFunction<>(value);
   }
 
-  private static class ConstantFunction<E> implements Function<Object, E>, Serializable {
-    private final @Nullable E value;
+  private static class ConstantFunction<E extends @Nullable Object>
+      implements Function<@Nullable Object, E>, Serializable {
+    @ParametricNullness private final E value;
 
-    public ConstantFunction(@Nullable E value) {
+    public ConstantFunction(@ParametricNullness E value) {
       this.value = value;
     }
 
     @Override
-    public E apply(@Nullable Object from) {
+    @ParametricNullness
+    public E apply(@CheckForNull Object from) {
       return value;
     }
 
     @Pure
     @Override
-    public boolean equals(@Nullable Object obj) {
+    public boolean equals(@CheckForNull Object obj) {
       if (obj instanceof ConstantFunction) {
         ConstantFunction<?> that = (ConstantFunction<?>) obj;
         return Objects.equal(value, that.value);
@@ -379,12 +403,14 @@ public String toString() {
    *
    * @since 10.0
    */
-  public static <T> Function<Object, T> forSupplier(Supplier<T> supplier) {
-    return new SupplierFunction<T>(supplier);
+  public static <F extends @Nullable Object, T extends @Nullable Object> Function<F, T> forSupplier(
+      Supplier<T> supplier) {
+    return new SupplierFunction<>(supplier);
   }
 
   /** @see Functions#forSupplier */
-  private static class SupplierFunction<T> implements Function<Object, T>, Serializable {
+  private static class SupplierFunction<F extends @Nullable Object, T extends @Nullable Object>
+      implements Function<F, T>, Serializable {
 
     private final Supplier<T> supplier;
 
@@ -393,14 +419,15 @@ private SupplierFunction(Supplier<T> supplier) {
     }
 
     @Override
-    public T apply(@Nullable Object input) {
+    @ParametricNullness
+    public T apply(@ParametricNullness F input) {
       return supplier.get();
     }
 
     @Override
-    public boolean equals(@Nullable Object obj) {
+    public boolean equals(@CheckForNull Object obj) {
       if (obj instanceof SupplierFunction) {
-        SupplierFunction<?> that = (SupplierFunction<?>) obj;
+        SupplierFunction<?, ?> that = (SupplierFunction<?, ?>) obj;
         return this.supplier.equals(that.supplier);
       }
       return false;
diff --git a/guava/src/com/google/common/base/Java8Compatibility.java b/guava/src/com/google/common/base/Java8Compatibility.java
new file mode 100644
index 000000000000..edc8b73bdd10
--- /dev/null
+++ b/guava/src/com/google/common/base/Java8Compatibility.java
@@ -0,0 +1,44 @@
+/*
+ * Copyright (C) 2020 The Guava Authors
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file except
+ * in compliance with the License. You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software distributed under the License
+ * is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express
+ * or implied. See the License for the specific language governing permissions and limitations under
+ * the License.
+ */
+
+package com.google.common.base;
+
+import com.google.common.annotations.GwtIncompatible;
+import java.nio.Buffer;
+
+/**
+ * Wrappers around {@link Buffer} methods that are covariantly overridden in Java 9+. See
+ * https://github.com/google/guava/issues/3990
+ */
+@GwtIncompatible
+@ElementTypesAreNonnullByDefault
+final class Java8Compatibility {
+  static void clear(Buffer b) {
+    b.clear();
+  }
+
+  static void flip(Buffer b) {
+    b.flip();
+  }
+
+  static void limit(Buffer b, int limit) {
+    b.limit(limit);
+  }
+
+  static void position(Buffer b, int position) {
+    b.position(position);
+  }
+
+  private Java8Compatibility() {}
+}
diff --git a/guava/src/com/google/common/base/Java8Usage.java b/guava/src/com/google/common/base/Java8Usage.java
deleted file mode 100644
index 78130cf676d9..000000000000
--- a/guava/src/com/google/common/base/Java8Usage.java
+++ /dev/null
@@ -1,45 +0,0 @@
-/*
- * Copyright (C) 2020 The Guava Authors
- *
- * Licensed under the Apache License, Version 2.0 (the "License");
- * you may not use this file except in compliance with the License.
- * You may obtain a copy of the License at
- *
- * http://www.apache.org/licenses/LICENSE-2.0
- *
- * Unless required by applicable law or agreed to in writing, software
- * distributed under the License is distributed on an "AS IS" BASIS,
- * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
- * See the License for the specific language governing permissions and
- * limitations under the License.
- */
-
-package com.google.common.base;
-
-import com.google.errorprone.annotations.CanIgnoreReturnValue;
-
-/**
- * A class that uses a couple Java 8 features but doesn't really do anything. This lets us attempt
- * to load it and log a warning if that fails, giving users advance notice of our dropping Java 8
- * support.
- */
-/*
- * This class should be annotated @GwtCompatible. But if we annotate it @GwtCompatible, then we need
- * to build GwtCompatible.java (-source 7 -target 7 in the Android flavor) before we build
- * Java8Usage.java (-source 8 target 8, which we already need to build before the rest of
- * common.base). We could configure Maven to do that, but it's easier to just skip the annotation.
- */
-final class Java8Usage {
-  @java.lang.annotation.Target(java.lang.annotation.ElementType.TYPE_USE)
-  @java.lang.annotation.Retention(java.lang.annotation.RetentionPolicy.RUNTIME)
-  private @interface SomeTypeAnnotation {}
-
-  @CanIgnoreReturnValue
-  static @SomeTypeAnnotation String performCheck() {
-    Runnable r = () -> {};
-    r.run();
-    return "";
-  }
-
-  private Java8Usage() {}
-}
diff --git a/guava/src/com/google/common/base/JdkPattern.java b/guava/src/com/google/common/base/JdkPattern.java
index 9334cd888ae2..356d807ee760 100644
--- a/guava/src/com/google/common/base/JdkPattern.java
+++ b/guava/src/com/google/common/base/JdkPattern.java
@@ -21,6 +21,7 @@
 import org.checkerframework.checker.index.qual.NonNegative;
 
 /** A regex pattern implementation which is backed by the {@link Pattern}. */
+@ElementTypesAreNonnullByDefault
 @GwtIncompatible
 final class JdkPattern extends CommonPattern implements Serializable {
   private final Pattern pattern;
diff --git a/guava/src/com/google/common/base/Joiner.java b/guava/src/com/google/common/base/Joiner.java
index 414e8b61be8f..836092879e44 100644
--- a/guava/src/com/google/common/base/Joiner.java
+++ b/guava/src/com/google/common/base/Joiner.java
@@ -15,6 +15,7 @@
 package com.google.common.base;
 
 import static com.google.common.base.Preconditions.checkNotNull;
+import static java.util.Objects.requireNonNull;
 
 import com.google.common.annotations.Beta;
 import com.google.common.annotations.GwtCompatible;
@@ -25,6 +26,7 @@
 import java.util.Iterator;
 import java.util.Map;
 import java.util.Map.Entry;
+import javax.annotation.CheckForNull;
 import org.checkerframework.checker.index.qual.NonNegative;
 import org.checkerframework.checker.nullness.qual.Nullable;
 import org.checkerframework.dataflow.qual.Pure;
@@ -67,6 +69,7 @@
  */
 @AnnotatedFor({"nullness"})
 @GwtCompatible
+@ElementTypesAreNonnullByDefault
 public class Joiner {
   /** Returns a joiner which automatically places {@code separator} between consecutive elements. */
   public static Joiner on(String separator) {
@@ -88,12 +91,19 @@ private Joiner(Joiner prototype) {
     this.separator = prototype.separator;
   }
 
+  /*
+   * In this file, we use <? extends @Nullable Object> instead of <?> to work around a Kotlin bug
+   * (see b/189937072 until we file a bug against Kotlin itself). (The two should be equivalent, so
+   * we normally prefer the shorter one.)
+   */
+
   /**
    * Appends the string representation of each of {@code parts}, using the previously configured
    * separator between each, to {@code appendable}.
    */
   @CanIgnoreReturnValue
-  public <A extends Appendable> A appendTo(A appendable, Iterable<?> parts) throws IOException {
+  public <A extends Appendable> A appendTo(A appendable, Iterable<? extends @Nullable Object> parts)
+      throws IOException {
     return appendTo(appendable, parts.iterator());
   }
 
@@ -104,7 +114,8 @@ public <A extends Appendable> A appendTo(A appendable, Iterable<?> parts) throws
    * @since 11.0
    */
   @CanIgnoreReturnValue
-  public <A extends Appendable> A appendTo(A appendable, Iterator<?> parts) throws IOException {
+  public <A extends Appendable> A appendTo(A appendable, Iterator<? extends @Nullable Object> parts)
+      throws IOException {
     checkNotNull(appendable);
     if (parts.hasNext()) {
       appendable.append(toString(parts.next()));
@@ -121,14 +132,18 @@ public <A extends Appendable> A appendTo(A appendable, Iterator<?> parts) throws
    * separator between each, to {@code appendable}.
    */
   @CanIgnoreReturnValue
-  public final <A extends Appendable> A appendTo(A appendable, @Nullable Object[] parts) throws IOException {
+  public final <A extends Appendable> A appendTo(A appendable, @Nullable Object[] parts)
+      throws IOException {
     return appendTo(appendable, Arrays.asList(parts));
   }
 
   /** Appends to {@code appendable} the string representation of each of the remaining arguments. */
   @CanIgnoreReturnValue
   public final <A extends Appendable> A appendTo(
-      A appendable, @Nullable Object first, @Nullable Object second, @Nullable Object... rest)
+      A appendable,
+      @CheckForNull Object first,
+      @CheckForNull Object second,
+      @Nullable Object... rest)
       throws IOException {
     return appendTo(appendable, iterable(first, second, rest));
   }
@@ -139,7 +154,8 @@ public final <A extends Appendable> A appendTo(
    * Iterable)}, except that it does not throw {@link IOException}.
    */
   @CanIgnoreReturnValue
-  public final StringBuilder appendTo(StringBuilder builder, Iterable<?> parts) {
+  public final StringBuilder appendTo(
+      StringBuilder builder, Iterable<? extends @Nullable Object> parts) {
     return appendTo(builder, parts.iterator());
   }
 
@@ -151,7 +167,8 @@ public final StringBuilder appendTo(StringBuilder builder, Iterable<?> parts) {
    * @since 11.0
    */
   @CanIgnoreReturnValue
-  public final StringBuilder appendTo(StringBuilder builder, Iterator<?> parts) {
+  public final StringBuilder appendTo(
+      StringBuilder builder, Iterator<? extends @Nullable Object> parts) {
     try {
       appendTo((Appendable) builder, parts);
     } catch (IOException impossible) {
@@ -177,7 +194,10 @@ public final StringBuilder appendTo(StringBuilder builder, @Nullable Object[] pa
    */
   @CanIgnoreReturnValue
   public final StringBuilder appendTo(
-      StringBuilder builder, @Nullable Object first, @Nullable Object second, @Nullable Object... rest) {
+      StringBuilder builder,
+      @CheckForNull Object first,
+      @CheckForNull Object second,
+      @Nullable Object... rest) {
     return appendTo(builder, iterable(first, second, rest));
   }
 
@@ -185,7 +205,7 @@ public final StringBuilder appendTo(
    * Returns a string containing the string representation of each of {@code parts}, using the
    * previously configured separator between each.
    */
-  public final String join(Iterable<?> parts) {
+  public final String join(Iterable<? extends @Nullable Object> parts) {
     return join(parts.iterator());
   }
 
@@ -195,7 +215,7 @@ public final String join(Iterable<?> parts) {
    *
    * @since 11.0
    */
-  public final String join(Iterator<?> parts) {
+  public final String join(Iterator<? extends @Nullable Object> parts) {
     return appendTo(new StringBuilder(), parts).toString();
   }
 
@@ -203,7 +223,7 @@ public final String join(Iterator<?> parts) {
    * Returns a string containing the string representation of each of {@code parts}, using the
    * previously configured separator between each.
    */
-  public final String join(Object[] parts) {
+  public final String join(@Nullable Object[] parts) {
     return join(Arrays.asList(parts));
   }
 
@@ -212,7 +232,7 @@ public final String join(Object[] parts) {
    * configured separator between each.
    */
   public final String join(
-      @Nullable Object first, @Nullable Object second, @Nullable Object... rest) {
+      @CheckForNull Object first, @CheckForNull Object second, @Nullable Object... rest) {
     return join(iterable(first, second, rest));
   }
 
@@ -220,11 +240,11 @@ public final String join(
    * Returns a joiner with the same behavior as this one, except automatically substituting {@code
    * nullText} for any provided null elements.
    */
-  public Joiner useForNull(final String nullText) {
+  public Joiner useForNull(String nullText) {
     checkNotNull(nullText);
     return new Joiner(this) {
       @Override
-      CharSequence toString(@Nullable Object part) {
+      CharSequence toString(@CheckForNull Object part) {
         return (part == null) ? nullText : Joiner.this.toString(part);
       }
 
@@ -247,7 +267,8 @@ public Joiner skipNulls() {
   public Joiner skipNulls() {
     return new Joiner(this) {
       @Override
-      public <A extends Appendable> A appendTo(A appendable, Iterator<?> parts) throws IOException {
+      public <A extends Appendable> A appendTo(
+          A appendable, Iterator<? extends @Nullable Object> parts) throws IOException {
         checkNotNull(appendable, "appendable");
         checkNotNull(parts, "parts");
         while (parts.hasNext()) {
@@ -453,13 +474,30 @@ public MapJoiner useForNull(String nullText) {
     }
   }
 
-  CharSequence toString(Object part) {
-    checkNotNull(part); // checkNotNull for GWT (do not optimize).
+  CharSequence toString(@CheckForNull Object part) {
+    /*
+     * requireNonNull is not safe: Joiner.on(...).join(somethingThatContainsNull) will indeed throw.
+     * However, Joiner.on(...).useForNull(...).join(somethingThatContainsNull) *is* safe -- because
+     * it returns a subclass of Joiner that overrides this method to tolerate null inputs.
+     *
+     * Unfortunately, we don't distinguish between these two cases in our public API: Joiner.on(...)
+     * and Joiner.on(...).useForNull(...) both declare the same return type: plain Joiner. To ensure
+     * that users *can* pass null arguments to Joiner, we annotate it as if it always tolerates null
+     * inputs, rather than as if it never tolerates them.
+     *
+     * We rely on checkers to implement special cases to catch dangerous calls to join(), etc. based
+     * on what they know about the particular Joiner instances the calls are performed on.
+     *
+     * (In addition to useForNull, we also offer skipNulls. It, too, tolerates null inputs, but its
+     * tolerance is implemented differently: Its implementation avoids calling this toString(Object)
+     * method in the first place.)
+     */
+    requireNonNull(part);
     return (part instanceof CharSequence) ? (CharSequence) part : part.toString();
   }
 
   private static Iterable<@Nullable Object> iterable(
-      final @Nullable Object first, final @Nullable Object second, final @Nullable Object[] rest) {
+      @CheckForNull Object first, @CheckForNull Object second, @Nullable Object[] rest) {
     checkNotNull(rest);
     return new AbstractList<@Nullable Object>() {
       @Pure
@@ -469,7 +507,8 @@ CharSequence toString(Object part) {
       }
 
       @Override
-      public @Nullable Object get(int index) {
+      @CheckForNull
+      public Object get(int index) {
         switch (index) {
           case 0:
             return first;
diff --git a/guava/src/com/google/common/base/MoreObjects.java b/guava/src/com/google/common/base/MoreObjects.java
index d028dc635466..400f56b082ac 100644
--- a/guava/src/com/google/common/base/MoreObjects.java
+++ b/guava/src/com/google/common/base/MoreObjects.java
@@ -18,8 +18,15 @@
 
 import com.google.common.annotations.GwtCompatible;
 import com.google.errorprone.annotations.CanIgnoreReturnValue;
+import java.lang.reflect.Array;
 import java.util.Arrays;
+import java.util.Collection;
 import java.util.logging.Logger;
+import java.util.Map;
+import java.util.OptionalDouble;
+import java.util.OptionalInt;
+import java.util.OptionalLong;
+import javax.annotation.CheckForNull;
 import org.checkerframework.checker.nullness.qual.NonNull;
 import org.checkerframework.checker.nullness.qual.Nullable;
 
@@ -35,6 +42,7 @@
  * @since 18.0 (since 2.0 as {@code Objects})
  */
 @GwtCompatible
+@ElementTypesAreNonnullByDefault
 public final class MoreObjects {
   /**
    * Returns the first of two given parameters that is not {@code null}, if either is, or otherwise
@@ -56,7 +64,24 @@ public final class MoreObjects {
    * @throws NullPointerException if both {@code first} and {@code second} are null
    * @since 18.0 (since 3.0 as {@code Objects.firstNonNull()}).
    */
-  public static <T> @NonNull T firstNonNull(T first, T second) {
+  /*
+   * We annotate firstNonNull in a way that protects against NullPointerException at the cost of
+   * forbidding some reasonable calls.
+   *
+   * The more permissive signature would be to accept (@CheckForNull T first, @CheckForNull T
+   * second), since it's OK for `second` to be null as long as `first` is not also null. But we
+   * expect for that flexibility to be useful relatively rarely: The more common use case is to
+   * supply a clearly non-null default, like `firstNonNull(someString, "")`. And users who really
+   * know that `first` is guaranteed non-null when `second` is null can write the logic out
+   * longhand, including a requireNonNull call, which calls attention to the fact that the static
+   * analyzer can't prove that the operation is safe.
+   *
+   * This matches the signature we currently have for requireNonNullElse in our own checker. (And
+   * that in turn matches that method's signature under the Checker Framework.) As always, we could
+   * consider the more flexible signature if we judge it worth the risks. If we do, we would likely
+   * update both methods so that they continue to match.
+   */
+  public static <T> T firstNonNull(@CheckForNull T first, T second) {
     if (first != null) {
       return first;
     }
@@ -147,6 +172,7 @@ public static final class ToStringHelper {
     private final ValueHolder holderHead = new ValueHolder();
     private ValueHolder holderTail = holderHead;
     private boolean omitNullValues = false;
+    private boolean omitEmptyValues = false;
 
     /** Use {@link MoreObjects#toStringHelper(Object)} to create an instance. */
     private ToStringHelper(String className) {
@@ -172,7 +198,7 @@ public ToStringHelper omitNullValues() {
      * called, in which case this name/value pair will not be added.
      */
     @CanIgnoreReturnValue
-    public ToStringHelper add(String name, @Nullable Object value) {
+    public ToStringHelper add(String name, @CheckForNull Object value) {
       return addHolder(name, value);
     }
 
@@ -183,7 +209,7 @@ public ToStringHelper add(String name, @Nullable Object value) {
      */
     @CanIgnoreReturnValue
     public ToStringHelper add(String name, boolean value) {
-      return addHolder(name, String.valueOf(value));
+      return addUnconditionalHolder(name, String.valueOf(value));
     }
 
     /**
@@ -193,7 +219,7 @@ public ToStringHelper add(String name, boolean value) {
      */
     @CanIgnoreReturnValue
     public ToStringHelper add(String name, char value) {
-      return addHolder(name, String.valueOf(value));
+      return addUnconditionalHolder(name, String.valueOf(value));
     }
 
     /**
@@ -203,7 +229,7 @@ public ToStringHelper add(String name, char value) {
      */
     @CanIgnoreReturnValue
     public ToStringHelper add(String name, double value) {
-      return addHolder(name, String.valueOf(value));
+      return addUnconditionalHolder(name, String.valueOf(value));
     }
 
     /**
@@ -213,7 +239,7 @@ public ToStringHelper add(String name, double value) {
      */
     @CanIgnoreReturnValue
     public ToStringHelper add(String name, float value) {
-      return addHolder(name, String.valueOf(value));
+      return addUnconditionalHolder(name, String.valueOf(value));
     }
 
     /**
@@ -223,7 +249,7 @@ public ToStringHelper add(String name, float value) {
      */
     @CanIgnoreReturnValue
     public ToStringHelper add(String name, int value) {
-      return addHolder(name, String.valueOf(value));
+      return addUnconditionalHolder(name, String.valueOf(value));
     }
 
     /**
@@ -233,7 +259,7 @@ public ToStringHelper add(String name, int value) {
      */
     @CanIgnoreReturnValue
     public ToStringHelper add(String name, long value) {
-      return addHolder(name, String.valueOf(value));
+      return addUnconditionalHolder(name, String.valueOf(value));
     }
 
     /**
@@ -243,7 +269,7 @@ public ToStringHelper add(String name, long value) {
      * readable name.
      */
     @CanIgnoreReturnValue
-    public ToStringHelper addValue(@Nullable Object value) {
+    public ToStringHelper addValue(@CheckForNull Object value) {
       return addHolder(value);
     }
 
@@ -257,7 +283,7 @@ public ToStringHelper addValue(@Nullable Object value) {
      */
     @CanIgnoreReturnValue
     public ToStringHelper addValue(boolean value) {
-      return addHolder(String.valueOf(value));
+      return addUnconditionalHolder(String.valueOf(value));
     }
 
     /**
@@ -270,7 +296,7 @@ public ToStringHelper addValue(boolean value) {
      */
     @CanIgnoreReturnValue
     public ToStringHelper addValue(char value) {
-      return addHolder(String.valueOf(value));
+      return addUnconditionalHolder(String.valueOf(value));
     }
 
     /**
@@ -283,7 +309,7 @@ public ToStringHelper addValue(char value) {
      */
     @CanIgnoreReturnValue
     public ToStringHelper addValue(double value) {
-      return addHolder(String.valueOf(value));
+      return addUnconditionalHolder(String.valueOf(value));
     }
 
     /**
@@ -296,7 +322,7 @@ public ToStringHelper addValue(double value) {
      */
     @CanIgnoreReturnValue
     public ToStringHelper addValue(float value) {
-      return addHolder(String.valueOf(value));
+      return addUnconditionalHolder(String.valueOf(value));
     }
 
     /**
@@ -309,7 +335,7 @@ public ToStringHelper addValue(float value) {
      */
     @CanIgnoreReturnValue
     public ToStringHelper addValue(int value) {
-      return addHolder(String.valueOf(value));
+      return addUnconditionalHolder(String.valueOf(value));
     }
 
     /**
@@ -322,7 +348,31 @@ public ToStringHelper addValue(int value) {
      */
     @CanIgnoreReturnValue
     public ToStringHelper addValue(long value) {
-      return addHolder(String.valueOf(value));
+      return addUnconditionalHolder(String.valueOf(value));
+    }
+
+    private static boolean isEmpty(Object value) {
+      // Put types estimated to be most frequent first.
+      if (value instanceof CharSequence) {
+        return ((CharSequence) value).length() == 0;
+      } else if (value instanceof Collection) {
+        return ((Collection<?>) value).isEmpty();
+      } else if (value instanceof Map) {
+        return ((Map<?, ?>) value).isEmpty();
+      } else if (value instanceof java.util.Optional) {
+        return !((java.util.Optional<?>) value).isPresent();
+      } else if (value instanceof OptionalInt) {
+        return !((OptionalInt) value).isPresent();
+      } else if (value instanceof OptionalLong) {
+        return !((OptionalLong) value).isPresent();
+      } else if (value instanceof OptionalDouble) {
+        return !((OptionalDouble) value).isPresent();
+      } else if (value instanceof Optional) {
+        return !((Optional) value).isPresent();
+      } else if (value.getClass().isArray()) {
+        return Array.getLength(value) == 0;
+      }
+      return false;
     }
 
     /**
@@ -337,13 +387,17 @@ public ToStringHelper addValue(long value) {
     public String toString() {
       // create a copy to keep it consistent in case value changes
       boolean omitNullValuesSnapshot = omitNullValues;
+      boolean omitEmptyValuesSnapshot = omitEmptyValues;
       String nextSeparator = "";
       StringBuilder builder = new StringBuilder(32).append(className).append('{');
       for (ValueHolder valueHolder = holderHead.next;
           valueHolder != null;
           valueHolder = valueHolder.next) {
         Object value = valueHolder.value;
-        if (!omitNullValuesSnapshot || value != null) {
+        if (valueHolder instanceof UnconditionalValueHolder
+            || (value == null
+                ? !omitNullValuesSnapshot
+                : (!omitEmptyValuesSnapshot || !isEmpty(value)))) {
           builder.append(nextSeparator);
           nextSeparator = ", ";
 
@@ -368,24 +422,51 @@ private ValueHolder addHolder() {
       return valueHolder;
     }
 
-    private ToStringHelper addHolder(@Nullable Object value) {
+    private ToStringHelper addHolder(@CheckForNull Object value) {
       ValueHolder valueHolder = addHolder();
       valueHolder.value = value;
       return this;
     }
 
-    private ToStringHelper addHolder(String name, @Nullable Object value) {
+    private ToStringHelper addHolder(String name, @CheckForNull Object value) {
       ValueHolder valueHolder = addHolder();
       valueHolder.value = value;
       valueHolder.name = checkNotNull(name);
       return this;
     }
 
-    private static final class ValueHolder {
-      @Nullable String name;
-      @Nullable Object value;
-      @Nullable ValueHolder next;
+    private UnconditionalValueHolder addUnconditionalHolder() {
+      UnconditionalValueHolder valueHolder = new UnconditionalValueHolder();
+      holderTail = holderTail.next = valueHolder;
+      return valueHolder;
+    }
+
+    private ToStringHelper addUnconditionalHolder(Object value) {
+      UnconditionalValueHolder valueHolder = addUnconditionalHolder();
+      valueHolder.value = value;
+      return this;
+    }
+
+    private ToStringHelper addUnconditionalHolder(String name, Object value) {
+      UnconditionalValueHolder valueHolder = addUnconditionalHolder();
+      valueHolder.value = value;
+      valueHolder.name = checkNotNull(name);
+      return this;
+    }
+
+    // Holder object for values that might be null and/or empty.
+    private static class ValueHolder {
+      @CheckForNull String name;
+      @CheckForNull Object value;
+      @CheckForNull ValueHolder next;
     }
+
+    /**
+     * Holder object for values that cannot be null or empty (will be printed unconditionally). This
+     * helps to shortcut most calls to isEmpty(), which is important because the check for emptiness
+     * is relatively expensive. Use a subtype so this also doesn't need any extra storage.
+     */
+    private static final class UnconditionalValueHolder extends ValueHolder {}
   }
 
   private MoreObjects() {}
diff --git a/guava/src/com/google/common/base/NullnessCasts.java b/guava/src/com/google/common/base/NullnessCasts.java
new file mode 100644
index 000000000000..1ada6bf26148
--- /dev/null
+++ b/guava/src/com/google/common/base/NullnessCasts.java
@@ -0,0 +1,60 @@
+/*
+ * Copyright (C) 2021 The Guava Authors
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file except
+ * in compliance with the License. You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software distributed under the License
+ * is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express
+ * or implied. See the License for the specific language governing permissions and limitations under
+ * the License.
+ */
+
+package com.google.common.base;
+
+import com.google.common.annotations.GwtCompatible;
+import javax.annotation.CheckForNull;
+import org.checkerframework.checker.nullness.qual.Nullable;
+
+/** A utility method to perform unchecked casts to suppress errors produced by nullness analyses. */
+@GwtCompatible
+@ElementTypesAreNonnullByDefault
+final class NullnessCasts {
+  /**
+   * Accepts a {@code @Nullable T} and returns a plain {@code T}, without performing any check that
+   * that conversion is safe.
+   *
+   * <p>This method is intended to help with usages of type parameters that have {@linkplain
+   * ParametricNullness parametric nullness}. If a type parameter instead ranges over only non-null
+   * types (or if the type is a non-variable type, like {@code String}), then code should almost
+   * never use this method, preferring instead to call {@code requireNonNull} so as to benefit from
+   * its runtime check.
+   *
+   * <p>An example use case for this method is in implementing an {@code Iterator<T>} whose {@code
+   * next} field is lazily initialized. The type of that field would be {@code @Nullable T}, and the
+   * code would be responsible for populating a "real" {@code T} (which might still be the value
+   * {@code null}!) before returning it to callers. Depending on how the code is structured, a
+   * nullness analysis might not understand that the field has been populated. To avoid that problem
+   * without having to add {@code @SuppressWarnings}, the code can call this method.
+   *
+   * <p>Why <i>not</i> just add {@code SuppressWarnings}? The problem is that this method is
+   * typically useful for {@code return} statements. That leaves the code with two options: Either
+   * add the suppression to the whole method (which turns off checking for a large section of code),
+   * or extract a variable, and put the suppression on that. However, a local variable typically
+   * doesn't work: Because nullness analyses typically infer the nullness of local variables,
+   * there's no way to assign a {@code @Nullable T} to a field {@code T foo;} and instruct the
+   * analysis that that means "plain {@code T}" rather than the inferred type {@code @Nullable T}.
+   * (Even if supported added {@code @NonNull}, that would not help, since the problem case
+   * addressed by this method is the case in which {@code T} has parametric nullness -- and thus its
+   * value may be legitimately {@code null}.)
+   */
+  @ParametricNullness
+  @SuppressWarnings("nullness")
+  static <T extends @Nullable Object> T uncheckedCastNullableTToT(@CheckForNull T t) {
+    return t;
+  }
+
+  private NullnessCasts() {}
+}
diff --git a/guava/src/com/google/common/base/Objects.java b/guava/src/com/google/common/base/Objects.java
index 02c149a4d059..c63ebc02487a 100644
--- a/guava/src/com/google/common/base/Objects.java
+++ b/guava/src/com/google/common/base/Objects.java
@@ -16,6 +16,7 @@
 
 import com.google.common.annotations.GwtCompatible;
 import java.util.Arrays;
+import javax.annotation.CheckForNull;
 import org.checkerframework.checker.nullness.qual.Nullable;
 import org.checkerframework.dataflow.qual.Pure;
 import org.checkerframework.framework.qual.AnnotatedFor;
@@ -32,6 +33,7 @@
  */
 @AnnotatedFor({"nullness"})
 @GwtCompatible
+@ElementTypesAreNonnullByDefault
 public final class Objects extends ExtraObjectsMethodsForWeb {
   private Objects() {}
 
@@ -51,7 +53,7 @@ private Objects() {}
    * <p><b>Note for Java 7 and later:</b> This method should be treated as deprecated; use {@link
    * java.util.Objects#equals} instead.
    */
-  public static boolean equal(@Nullable Object a, @Nullable Object b) {
+  public static boolean equal(@CheckForNull Object a, @CheckForNull Object b) {
     return a == b || (a != null && a.equals(b));
   }
 
@@ -77,7 +79,7 @@ public static boolean equal(@Nullable Object a, @Nullable Object b) {
    * java.util.Objects#hash} instead.
    */
   @Pure
-  public static int hashCode(@Nullable Object @Nullable ... objects) {
+  public static int hashCode(@CheckForNull @Nullable Object... objects) {
     return Arrays.hashCode(objects);
   }
 }
diff --git a/guava/src/com/google/common/base/Optional.java b/guava/src/com/google/common/base/Optional.java
index 5d17057ea14e..0b9a5cf993c4 100644
--- a/guava/src/com/google/common/base/Optional.java
+++ b/guava/src/com/google/common/base/Optional.java
@@ -15,13 +15,14 @@
 package com.google.common.base;
 
 import static com.google.common.base.Preconditions.checkNotNull;
-import com.google.errorprone.annotations.DoNotMock;
 
 import com.google.common.annotations.Beta;
 import com.google.common.annotations.GwtCompatible;
+import com.google.errorprone.annotations.DoNotMock;
 import java.io.Serializable;
 import java.util.Iterator;
 import java.util.Set;
+import javax.annotation.CheckForNull;
 import org.checkerframework.checker.nullness.qual.NonNull;
 import org.checkerframework.checker.nullness.qual.Nullable;
 import org.checkerframework.checker.nullness.qual.PolyNull;
@@ -88,7 +89,8 @@
 @Covariant(0)
 @DoNotMock("Use Optional.of(value) or Optional.absent()")
 @GwtCompatible(serializable = true)
-public abstract @NonNull class Optional<T> implements Serializable {
+@ElementTypesAreNonnullByDefault
+public abstract class Optional<T> implements Serializable {
   /**
    * Returns an {@code Optional} instance with no contained reference.
    *
@@ -118,7 +120,7 @@ public static <T> Optional<T> of(@NonNull T reference) {
    * <p><b>Comparison to {@code java.util.Optional}:</b> this method is equivalent to Java 8's
    * {@code Optional.ofNullable}.
    */
-  public static <T> Optional<T> fromNullable(@Nullable T nullableReference) {
+  public static <T> Optional<T> fromNullable(@CheckForNull T nullableReference) {
     return (nullableReference == null) ? Optional.<T>absent() : new Present<T>(nullableReference);
   }
 
@@ -128,10 +130,8 @@ public static <T> Optional<T> fromNullable(@Nullable T nullableReference) {
    *
    * @since 21.0
    */
-  @SuppressWarnings("nullness:return.type.incompatible") // Known issue with behaviour of @PolyNull
-  // with ternary operator, see: https://github.com/typetools/checker-framework/issues/1170
-  public static <T> @PolyNull Optional<T> fromJavaUtil(
-      java.util.@PolyNull Optional<T> javaUtilOptional) {
+  @CheckForNull
+  public static <T> Optional<T> fromJavaUtil(@CheckForNull java.util.Optional<T> javaUtilOptional) {
     return (javaUtilOptional == null) ? null : fromNullable(javaUtilOptional.orElse(null));
   }
 
@@ -148,10 +148,8 @@ public static <T> Optional<T> fromNullable(@Nullable T nullableReference) {
    *
    * @since 21.0
    */
-  @SuppressWarnings("nullness:return.type.incompatible") // Known issue with behaviour of @PolyNull
-  // with ternary operator, see: https://github.com/typetools/checker-framework/issues/1170
-  public static <T> java.util.@PolyNull Optional<T> toJavaUtil(
-      @PolyNull Optional<T> googleOptional) {
+  @CheckForNull
+  public static <T> java.util.Optional<T> toJavaUtil(@CheckForNull Optional<T> googleOptional) {
     return googleOptional == null ? null : googleOptional.toJavaUtil();
   }
 
@@ -258,7 +256,8 @@ public java.util.Optional<T> toJavaUtil() {
    * <p><b>Comparison to {@code java.util.Optional}:</b> this method is equivalent to Java 8's
    * {@code Optional.orElse(null)}.
    */
-  public abstract @Nullable T orNull();
+  @CheckForNull
+  public abstract T orNull();
 
   /**
    * Returns an immutable singleton {@link Set} whose only element is the contained instance if it
@@ -306,7 +305,7 @@ public java.util.Optional<T> toJavaUtil() {
    * <p><b>Comparison to {@code java.util.Optional}:</b> no differences.
    */
   @Override
-  public abstract boolean equals(@Nullable Object object);
+  public abstract boolean equals(@CheckForNull Object object);
 
   /**
    * Returns a hash code for this instance.
@@ -351,8 +350,7 @@ public Iterator<T> iterator() {
               checkNotNull(optionals.iterator());
 
           @Override
-          @SuppressWarnings("nullness:return.type.incompatible") // If endOfData is invoked during
-          // execution the returned value is ignored
+          @CheckForNull
           protected T computeNext() {
             while (iterator.hasNext()) {
               Optional<? extends T> optional = iterator.next();
diff --git a/guava/src/com/google/common/base/PairwiseEquivalence.java b/guava/src/com/google/common/base/PairwiseEquivalence.java
index 89cb562092c0..74be27fd7c6f 100644
--- a/guava/src/com/google/common/base/PairwiseEquivalence.java
+++ b/guava/src/com/google/common/base/PairwiseEquivalence.java
@@ -17,14 +17,16 @@
 import com.google.common.annotations.GwtCompatible;
 import java.io.Serializable;
 import java.util.Iterator;
+import javax.annotation.CheckForNull;
 import org.checkerframework.checker.nullness.qual.Nullable;
 
 @GwtCompatible(serializable = true)
-final class PairwiseEquivalence<T> extends Equivalence<Iterable<T>> implements Serializable {
+@ElementTypesAreNonnullByDefault
+final class PairwiseEquivalence<E, T extends @Nullable E> extends Equivalence<Iterable<T>>
+    implements Serializable {
+  final Equivalence<E> elementEquivalence;
 
-  final Equivalence<? super T> elementEquivalence;
-
-  PairwiseEquivalence(Equivalence<? super T> elementEquivalence) {
+  PairwiseEquivalence(Equivalence<E> elementEquivalence) {
     this.elementEquivalence = Preconditions.checkNotNull(elementEquivalence);
   }
 
@@ -52,9 +54,9 @@ protected int doHash(Iterable<T> iterable) {
   }
 
   @Override
-  public boolean equals(@Nullable Object object) {
+  public boolean equals(@CheckForNull Object object) {
     if (object instanceof PairwiseEquivalence) {
-      PairwiseEquivalence<?> that = (PairwiseEquivalence<?>) object;
+      PairwiseEquivalence<?, ?> that = (PairwiseEquivalence<?, ?>) object;
       return this.elementEquivalence.equals(that.elementEquivalence);
     }
 
diff --git a/guava/src/com/google/common/base/ParametricNullness.java b/guava/src/com/google/common/base/ParametricNullness.java
new file mode 100644
index 000000000000..5b595adb3ffb
--- /dev/null
+++ b/guava/src/com/google/common/base/ParametricNullness.java
@@ -0,0 +1,52 @@
+/*
+ * Copyright (C) 2021 The Guava Authors
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package com.google.common.base;
+
+import static java.lang.annotation.ElementType.FIELD;
+import static java.lang.annotation.ElementType.METHOD;
+import static java.lang.annotation.ElementType.PARAMETER;
+import static java.lang.annotation.RetentionPolicy.RUNTIME;
+
+import com.google.common.annotations.GwtCompatible;
+import java.lang.annotation.Retention;
+import java.lang.annotation.Target;
+
+/**
+ * Marks a "top-level" type-variable usage as the closest we can get to "non-nullable when
+ * non-nullable; nullable when nullable" (like the Android <a
+ * href="https://android.googlesource.com/platform/libcore/+/master/luni/src/main/java/libcore/util/NullFromTypeParam.java">{@code
+ * NullFromTypeParam}</a>).
+ *
+ * <p>Consumers of this annotation include:
+ *
+ * <ul>
+ *   <li>Kotlin, for which it makes the type-variable usage (a) a Kotlin platform type when the type
+ *       argument is non-nullable and (b) nullable when the type argument is nullable. We use this
+ *       to "undo" {@link ElementTypesAreNonnullByDefault}.
+ *   <li><a href="https://developers.google.com/j2objc">J2ObjC</a>
+ *   <li>{@code NullPointerTester}, at least in the Android backport (where the type-use annotations
+ *       {@code NullPointerTester} would need are not available) and in case of <a
+ *       href="https://bugs.openjdk.java.net/browse/JDK-8202469">JDK-8202469</a>
+ * </ul>
+ *
+ */
+@GwtCompatible
+@Retention(RUNTIME)
+@Target({FIELD, METHOD, PARAMETER})
+@javax.annotation.meta.TypeQualifierNickname
+@javax.annotation.Nonnull(when = javax.annotation.meta.When.UNKNOWN)
+@interface ParametricNullness {}
diff --git a/guava/src/com/google/common/base/PatternCompiler.java b/guava/src/com/google/common/base/PatternCompiler.java
index 813a25f65b86..72a45faae963 100644
--- a/guava/src/com/google/common/base/PatternCompiler.java
+++ b/guava/src/com/google/common/base/PatternCompiler.java
@@ -22,6 +22,7 @@
  * java.util.ServiceLoader} mechanism.
  */
 @GwtIncompatible
+@ElementTypesAreNonnullByDefault
 interface PatternCompiler {
   /**
    * Compiles the given pattern.
diff --git a/guava/src/com/google/common/base/Platform.java b/guava/src/com/google/common/base/Platform.java
index 835f587232b4..e6601d5db7dc 100644
--- a/guava/src/com/google/common/base/Platform.java
+++ b/guava/src/com/google/common/base/Platform.java
@@ -21,6 +21,7 @@
 import java.util.logging.Level;
 import java.util.logging.Logger;
 import java.util.regex.Pattern;
+import javax.annotation.CheckForNull;
 import org.checkerframework.checker.nullness.qual.EnsuresNonNullIf;
 import org.checkerframework.checker.nullness.qual.Nullable;
 import org.checkerframework.framework.qual.AnnotatedFor;
@@ -32,6 +33,7 @@
  */
 @AnnotatedFor({"nullness"})
 @GwtCompatible(emulated = true)
+@ElementTypesAreNonnullByDefault
 final class Platform {
   private static final Logger logger = Logger.getLogger(Platform.class.getName());
   private static final PatternCompiler patternCompiler = loadPatternCompiler();
@@ -48,7 +50,7 @@ static CharMatcher precomputeCharMatcher(CharMatcher matcher) {
     return matcher.precomputedInternal();
   }
 
-  @SuppressWarnings("nullness:argument.type.incompatible") // ref.get returns null in case the object
+  @SuppressWarnings("nullness:argument") // ref.get returns null in case the object
   // that it refers to is cleared or garbage collected which is unlikely during normal program
   // execution. Optional.of always return a non-null value for non-null argument.
   static <T extends Enum<T>> Optional<T> getEnumIfPresent(Class<T> enumClass, String value) {
@@ -60,8 +62,7 @@ static String formatCompact4Digits(double value) {
     return String.format(Locale.ROOT, "%.4g", value);
   }
 
-  @EnsuresNonNullIf(expression = "#1", result = false)
-  static boolean stringIsNullOrEmpty(@Nullable String string) {
+  static boolean stringIsNullOrEmpty(@CheckForNull String string) {
     return string == null || string.isEmpty();
   }
 
@@ -71,7 +72,7 @@ static boolean stringIsNullOrEmpty(@Nullable String string) {
    * @param string the string to test and possibly return
    * @return {@code string} if it is not null; {@code ""} otherwise
    */
-  static String nullToEmpty(@Nullable String string) {
+  static String nullToEmpty(@CheckForNull String string) {
     return (string == null) ? "" : string;
   }
 
@@ -81,7 +82,8 @@ static String nullToEmpty(@Nullable String string) {
    * @param string the string to test and possibly return
    * @return {@code string} if it is not empty; {@code null} otherwise
    */
-  static @Nullable String emptyToNull(@Nullable String string) {
+  @CheckForNull
+  static String emptyToNull(@CheckForNull String string) {
     return stringIsNullOrEmpty(string) ? null : string;
   }
 
diff --git a/guava/src/com/google/common/base/Preconditions.java b/guava/src/com/google/common/base/Preconditions.java
index 71fbf1fdedea..5ffc756bf58a 100644
--- a/guava/src/com/google/common/base/Preconditions.java
+++ b/guava/src/com/google/common/base/Preconditions.java
@@ -15,11 +15,11 @@
 package com.google.common.base;
 
 import static com.google.common.base.Strings.lenientFormat;
-import static java.util.logging.Level.WARNING;
 
 import com.google.common.annotations.GwtCompatible;
 import com.google.errorprone.annotations.CanIgnoreReturnValue;
 import java.util.logging.Logger;
+import javax.annotation.CheckForNull;
 import org.checkerframework.checker.index.qual.NonNegative;
 import org.checkerframework.checker.nullness.qual.NonNull;
 import org.checkerframework.checker.nullness.qual.Nullable;
@@ -120,9 +120,12 @@
  */
 @AnnotatedFor({"nullness"})
 @GwtCompatible
+@ElementTypesAreNonnullByDefault
 public final class Preconditions {
   private Preconditions() {}
 
+  // TODO(cpovirk): Standardize parameter names (expression vs. b, reference vs. obj).
+
   /**
    * Ensures the truth of an expression involving one or more parameters to the calling method.
    *
@@ -145,7 +148,7 @@ public static void checkArgument(boolean expression) {
    * @throws IllegalArgumentException if {@code expression} is false
    */
   @Pure
-  public static void checkArgument(boolean expression, @Nullable Object errorMessage) {
+  public static void checkArgument(boolean expression, @CheckForNull Object errorMessage) {
     if (!expression) {
       throw new IllegalArgumentException(String.valueOf(errorMessage));
     }
@@ -167,8 +170,8 @@ public static void checkArgument(boolean expression, @Nullable Object errorMessa
   @Pure
   public static void checkArgument(
       boolean expression,
-      @Nullable String errorMessageTemplate,
-      @Nullable Object @Nullable ... errorMessageArgs) {
+      String errorMessageTemplate,
+      @CheckForNull @Nullable Object... errorMessageArgs) {
     if (!expression) {
       throw new IllegalArgumentException(lenientFormat(errorMessageTemplate, errorMessageArgs));
     }
@@ -182,7 +185,7 @@ public static void checkArgument(
    * @since 20.0 (varargs overload since 2.0)
    */
   @Pure
-  public static void checkArgument(boolean b, @Nullable String errorMessageTemplate, char p1) {
+  public static void checkArgument(boolean b, String errorMessageTemplate, char p1) {
     if (!b) {
       throw new IllegalArgumentException(lenientFormat(errorMessageTemplate, p1));
     }
@@ -196,7 +199,7 @@ public static void checkArgument(boolean b, @Nullable String errorMessageTemplat
    * @since 20.0 (varargs overload since 2.0)
    */
   @Pure
-  public static void checkArgument(boolean b, @Nullable String errorMessageTemplate, int p1) {
+  public static void checkArgument(boolean b, String errorMessageTemplate, int p1) {
     if (!b) {
       throw new IllegalArgumentException(lenientFormat(errorMessageTemplate, p1));
     }
@@ -210,7 +213,7 @@ public static void checkArgument(boolean b, @Nullable String errorMessageTemplat
    * @since 20.0 (varargs overload since 2.0)
    */
   @Pure
-  public static void checkArgument(boolean b, @Nullable String errorMessageTemplate, long p1) {
+  public static void checkArgument(boolean b, String errorMessageTemplate, long p1) {
     if (!b) {
       throw new IllegalArgumentException(lenientFormat(errorMessageTemplate, p1));
     }
@@ -225,7 +228,7 @@ public static void checkArgument(boolean b, @Nullable String errorMessageTemplat
    */
   @Pure
   public static void checkArgument(
-      boolean b, @Nullable String errorMessageTemplate, @Nullable Object p1) {
+      boolean b, String errorMessageTemplate, @CheckForNull Object p1) {
     if (!b) {
       throw new IllegalArgumentException(lenientFormat(errorMessageTemplate, p1));
     }
@@ -239,8 +242,7 @@ public static void checkArgument(
    * @since 20.0 (varargs overload since 2.0)
    */
   @Pure
-  public static void checkArgument(
-      boolean b, @Nullable String errorMessageTemplate, char p1, char p2) {
+  public static void checkArgument(boolean b, String errorMessageTemplate, char p1, char p2) {
     if (!b) {
       throw new IllegalArgumentException(lenientFormat(errorMessageTemplate, p1, p2));
     }
@@ -254,8 +256,7 @@ public static void checkArgument(
    * @since 20.0 (varargs overload since 2.0)
    */
   @Pure
-  public static void checkArgument(
-      boolean b, @Nullable String errorMessageTemplate, char p1, int p2) {
+  public static void checkArgument(boolean b, String errorMessageTemplate, char p1, int p2) {
     if (!b) {
       throw new IllegalArgumentException(lenientFormat(errorMessageTemplate, p1, p2));
     }
@@ -269,8 +270,7 @@ public static void checkArgument(
    * @since 20.0 (varargs overload since 2.0)
    */
   @Pure
-  public static void checkArgument(
-      boolean b, @Nullable String errorMessageTemplate, char p1, long p2) {
+  public static void checkArgument(boolean b, String errorMessageTemplate, char p1, long p2) {
     if (!b) {
       throw new IllegalArgumentException(lenientFormat(errorMessageTemplate, p1, p2));
     }
@@ -285,7 +285,7 @@ public static void checkArgument(
    */
   @Pure
   public static void checkArgument(
-      boolean b, @Nullable String errorMessageTemplate, char p1, @Nullable Object p2) {
+      boolean b, String errorMessageTemplate, char p1, @CheckForNull Object p2) {
     if (!b) {
       throw new IllegalArgumentException(lenientFormat(errorMessageTemplate, p1, p2));
     }
@@ -299,8 +299,7 @@ public static void checkArgument(
    * @since 20.0 (varargs overload since 2.0)
    */
   @Pure
-  public static void checkArgument(
-      boolean b, @Nullable String errorMessageTemplate, int p1, char p2) {
+  public static void checkArgument(boolean b, String errorMessageTemplate, int p1, char p2) {
     if (!b) {
       throw new IllegalArgumentException(lenientFormat(errorMessageTemplate, p1, p2));
     }
@@ -314,8 +313,7 @@ public static void checkArgument(
    * @since 20.0 (varargs overload since 2.0)
    */
   @Pure
-  public static void checkArgument(
-      boolean b, @Nullable String errorMessageTemplate, int p1, int p2) {
+  public static void checkArgument(boolean b, String errorMessageTemplate, int p1, int p2) {
     if (!b) {
       throw new IllegalArgumentException(lenientFormat(errorMessageTemplate, p1, p2));
     }
@@ -329,8 +327,7 @@ public static void checkArgument(
    * @since 20.0 (varargs overload since 2.0)
    */
   @Pure
-  public static void checkArgument(
-      boolean b, @Nullable String errorMessageTemplate, int p1, long p2) {
+  public static void checkArgument(boolean b, String errorMessageTemplate, int p1, long p2) {
     if (!b) {
       throw new IllegalArgumentException(lenientFormat(errorMessageTemplate, p1, p2));
     }
@@ -345,7 +342,7 @@ public static void checkArgument(
    */
   @Pure
   public static void checkArgument(
-      boolean b, @Nullable String errorMessageTemplate, int p1, @Nullable Object p2) {
+      boolean b, String errorMessageTemplate, int p1, @CheckForNull Object p2) {
     if (!b) {
       throw new IllegalArgumentException(lenientFormat(errorMessageTemplate, p1, p2));
     }
@@ -359,8 +356,7 @@ public static void checkArgument(
    * @since 20.0 (varargs overload since 2.0)
    */
   @Pure
-  public static void checkArgument(
-      boolean b, @Nullable String errorMessageTemplate, long p1, char p2) {
+  public static void checkArgument(boolean b, String errorMessageTemplate, long p1, char p2) {
     if (!b) {
       throw new IllegalArgumentException(lenientFormat(errorMessageTemplate, p1, p2));
     }
@@ -374,8 +370,7 @@ public static void checkArgument(
    * @since 20.0 (varargs overload since 2.0)
    */
   @Pure
-  public static void checkArgument(
-      boolean b, @Nullable String errorMessageTemplate, long p1, int p2) {
+  public static void checkArgument(boolean b, String errorMessageTemplate, long p1, int p2) {
     if (!b) {
       throw new IllegalArgumentException(lenientFormat(errorMessageTemplate, p1, p2));
     }
@@ -389,8 +384,7 @@ public static void checkArgument(
    * @since 20.0 (varargs overload since 2.0)
    */
   @Pure
-  public static void checkArgument(
-      boolean b, @Nullable String errorMessageTemplate, long p1, long p2) {
+  public static void checkArgument(boolean b, String errorMessageTemplate, long p1, long p2) {
     if (!b) {
       throw new IllegalArgumentException(lenientFormat(errorMessageTemplate, p1, p2));
     }
@@ -405,7 +399,7 @@ public static void checkArgument(
    */
   @Pure
   public static void checkArgument(
-      boolean b, @Nullable String errorMessageTemplate, long p1, @Nullable Object p2) {
+      boolean b, String errorMessageTemplate, long p1, @CheckForNull Object p2) {
     if (!b) {
       throw new IllegalArgumentException(lenientFormat(errorMessageTemplate, p1, p2));
     }
@@ -420,7 +414,7 @@ public static void checkArgument(
    */
   @Pure
   public static void checkArgument(
-      boolean b, @Nullable String errorMessageTemplate, @Nullable Object p1, char p2) {
+      boolean b, String errorMessageTemplate, @CheckForNull Object p1, char p2) {
     if (!b) {
       throw new IllegalArgumentException(lenientFormat(errorMessageTemplate, p1, p2));
     }
@@ -435,7 +429,7 @@ public static void checkArgument(
    */
   @Pure
   public static void checkArgument(
-      boolean b, @Nullable String errorMessageTemplate, @Nullable Object p1, int p2) {
+      boolean b, String errorMessageTemplate, @CheckForNull Object p1, int p2) {
     if (!b) {
       throw new IllegalArgumentException(lenientFormat(errorMessageTemplate, p1, p2));
     }
@@ -450,7 +444,7 @@ public static void checkArgument(
    */
   @Pure
   public static void checkArgument(
-      boolean b, @Nullable String errorMessageTemplate, @Nullable Object p1, long p2) {
+      boolean b, String errorMessageTemplate, @CheckForNull Object p1, long p2) {
     if (!b) {
       throw new IllegalArgumentException(lenientFormat(errorMessageTemplate, p1, p2));
     }
@@ -465,7 +459,7 @@ public static void checkArgument(
    */
   @Pure
   public static void checkArgument(
-      boolean b, @Nullable String errorMessageTemplate, @Nullable Object p1, @Nullable Object p2) {
+      boolean b, String errorMessageTemplate, @CheckForNull Object p1, @CheckForNull Object p2) {
     if (!b) {
       throw new IllegalArgumentException(lenientFormat(errorMessageTemplate, p1, p2));
     }
@@ -481,10 +475,10 @@ public static void checkArgument(
   @Pure
   public static void checkArgument(
       boolean b,
-      @Nullable String errorMessageTemplate,
-      @Nullable Object p1,
-      @Nullable Object p2,
-      @Nullable Object p3) {
+      String errorMessageTemplate,
+      @CheckForNull Object p1,
+      @CheckForNull Object p2,
+      @CheckForNull Object p3) {
     if (!b) {
       throw new IllegalArgumentException(lenientFormat(errorMessageTemplate, p1, p2, p3));
     }
@@ -500,11 +494,11 @@ public static void checkArgument(
   @Pure
   public static void checkArgument(
       boolean b,
-      @Nullable String errorMessageTemplate,
-      @Nullable Object p1,
-      @Nullable Object p2,
-      @Nullable Object p3,
-      @Nullable Object p4) {
+      String errorMessageTemplate,
+      @CheckForNull Object p1,
+      @CheckForNull Object p2,
+      @CheckForNull Object p3,
+      @CheckForNull Object p4) {
     if (!b) {
       throw new IllegalArgumentException(lenientFormat(errorMessageTemplate, p1, p2, p3, p4));
     }
@@ -534,7 +528,7 @@ public static void checkState(boolean expression) {
    * @throws IllegalStateException if {@code expression} is false
    * @see Verify#verify Verify.verify()
    */
-  public static void checkState(boolean expression, @Nullable Object errorMessage) {
+  public static void checkState(boolean expression, @CheckForNull Object errorMessage) {
     if (!expression) {
       throw new IllegalStateException(String.valueOf(errorMessage));
     }
@@ -557,8 +551,16 @@ public static void checkState(boolean expression, @Nullable Object errorMessage)
    */
   public static void checkState(
       boolean expression,
-      @Nullable String errorMessageTemplate,
-      @Nullable Object @Nullable ... errorMessageArgs) {
+      /*
+       * TODO(cpovirk): Consider removing @CheckForNull here, as we've done with the other methods'
+       * errorMessageTemplate parameters: It it unlikely that callers intend for their string
+       * template to be null (though we do handle that case gracefully at runtime). I've left this
+       * one as it is because one of our users has defined a wrapper API around Preconditions,
+       * declaring a checkState method that accepts a possibly null template. So we'd need to update
+       * that user first.
+       */
+      @CheckForNull String errorMessageTemplate,
+      @CheckForNull @Nullable Object... errorMessageArgs) {
     if (!expression) {
       throw new IllegalStateException(lenientFormat(errorMessageTemplate, errorMessageArgs));
     }
@@ -572,7 +574,7 @@ public static void checkState(
    *
    * @since 20.0 (varargs overload since 2.0)
    */
-  public static void checkState(boolean b, @Nullable String errorMessageTemplate, char p1) {
+  public static void checkState(boolean b, String errorMessageTemplate, char p1) {
     if (!b) {
       throw new IllegalStateException(lenientFormat(errorMessageTemplate, p1));
     }
@@ -586,7 +588,7 @@ public static void checkState(boolean b, @Nullable String errorMessageTemplate,
    *
    * @since 20.0 (varargs overload since 2.0)
    */
-  public static void checkState(boolean b, @Nullable String errorMessageTemplate, int p1) {
+  public static void checkState(boolean b, String errorMessageTemplate, int p1) {
     if (!b) {
       throw new IllegalStateException(lenientFormat(errorMessageTemplate, p1));
     }
@@ -600,7 +602,7 @@ public static void checkState(boolean b, @Nullable String errorMessageTemplate,
    *
    * @since 20.0 (varargs overload since 2.0)
    */
-  public static void checkState(boolean b, @Nullable String errorMessageTemplate, long p1) {
+  public static void checkState(boolean b, String errorMessageTemplate, long p1) {
     if (!b) {
       throw new IllegalStateException(lenientFormat(errorMessageTemplate, p1));
     }
@@ -614,8 +616,7 @@ public static void checkState(boolean b, @Nullable String errorMessageTemplate,
    *
    * @since 20.0 (varargs overload since 2.0)
    */
-  public static void checkState(
-      boolean b, @Nullable String errorMessageTemplate, @Nullable Object p1) {
+  public static void checkState(boolean b, String errorMessageTemplate, @CheckForNull Object p1) {
     if (!b) {
       throw new IllegalStateException(lenientFormat(errorMessageTemplate, p1));
     }
@@ -629,8 +630,7 @@ public static void checkState(
    *
    * @since 20.0 (varargs overload since 2.0)
    */
-  public static void checkState(
-      boolean b, @Nullable String errorMessageTemplate, char p1, char p2) {
+  public static void checkState(boolean b, String errorMessageTemplate, char p1, char p2) {
     if (!b) {
       throw new IllegalStateException(lenientFormat(errorMessageTemplate, p1, p2));
     }
@@ -644,7 +644,7 @@ public static void checkState(
    *
    * @since 20.0 (varargs overload since 2.0)
    */
-  public static void checkState(boolean b, @Nullable String errorMessageTemplate, char p1, int p2) {
+  public static void checkState(boolean b, String errorMessageTemplate, char p1, int p2) {
     if (!b) {
       throw new IllegalStateException(lenientFormat(errorMessageTemplate, p1, p2));
     }
@@ -658,8 +658,7 @@ public static void checkState(boolean b, @Nullable String errorMessageTemplate,
    *
    * @since 20.0 (varargs overload since 2.0)
    */
-  public static void checkState(
-      boolean b, @Nullable String errorMessageTemplate, char p1, long p2) {
+  public static void checkState(boolean b, String errorMessageTemplate, char p1, long p2) {
     if (!b) {
       throw new IllegalStateException(lenientFormat(errorMessageTemplate, p1, p2));
     }
@@ -674,7 +673,7 @@ public static void checkState(
    * @since 20.0 (varargs overload since 2.0)
    */
   public static void checkState(
-      boolean b, @Nullable String errorMessageTemplate, char p1, @Nullable Object p2) {
+      boolean b, String errorMessageTemplate, char p1, @CheckForNull Object p2) {
     if (!b) {
       throw new IllegalStateException(lenientFormat(errorMessageTemplate, p1, p2));
     }
@@ -688,7 +687,7 @@ public static void checkState(
    *
    * @since 20.0 (varargs overload since 2.0)
    */
-  public static void checkState(boolean b, @Nullable String errorMessageTemplate, int p1, char p2) {
+  public static void checkState(boolean b, String errorMessageTemplate, int p1, char p2) {
     if (!b) {
       throw new IllegalStateException(lenientFormat(errorMessageTemplate, p1, p2));
     }
@@ -702,7 +701,7 @@ public static void checkState(boolean b, @Nullable String errorMessageTemplate,
    *
    * @since 20.0 (varargs overload since 2.0)
    */
-  public static void checkState(boolean b, @Nullable String errorMessageTemplate, int p1, int p2) {
+  public static void checkState(boolean b, String errorMessageTemplate, int p1, int p2) {
     if (!b) {
       throw new IllegalStateException(lenientFormat(errorMessageTemplate, p1, p2));
     }
@@ -716,7 +715,7 @@ public static void checkState(boolean b, @Nullable String errorMessageTemplate,
    *
    * @since 20.0 (varargs overload since 2.0)
    */
-  public static void checkState(boolean b, @Nullable String errorMessageTemplate, int p1, long p2) {
+  public static void checkState(boolean b, String errorMessageTemplate, int p1, long p2) {
     if (!b) {
       throw new IllegalStateException(lenientFormat(errorMessageTemplate, p1, p2));
     }
@@ -731,7 +730,7 @@ public static void checkState(boolean b, @Nullable String errorMessageTemplate,
    * @since 20.0 (varargs overload since 2.0)
    */
   public static void checkState(
-      boolean b, @Nullable String errorMessageTemplate, int p1, @Nullable Object p2) {
+      boolean b, String errorMessageTemplate, int p1, @CheckForNull Object p2) {
     if (!b) {
       throw new IllegalStateException(lenientFormat(errorMessageTemplate, p1, p2));
     }
@@ -745,8 +744,7 @@ public static void checkState(
    *
    * @since 20.0 (varargs overload since 2.0)
    */
-  public static void checkState(
-      boolean b, @Nullable String errorMessageTemplate, long p1, char p2) {
+  public static void checkState(boolean b, String errorMessageTemplate, long p1, char p2) {
     if (!b) {
       throw new IllegalStateException(lenientFormat(errorMessageTemplate, p1, p2));
     }
@@ -760,7 +758,7 @@ public static void checkState(
    *
    * @since 20.0 (varargs overload since 2.0)
    */
-  public static void checkState(boolean b, @Nullable String errorMessageTemplate, long p1, int p2) {
+  public static void checkState(boolean b, String errorMessageTemplate, long p1, int p2) {
     if (!b) {
       throw new IllegalStateException(lenientFormat(errorMessageTemplate, p1, p2));
     }
@@ -774,8 +772,7 @@ public static void checkState(boolean b, @Nullable String errorMessageTemplate,
    *
    * @since 20.0 (varargs overload since 2.0)
    */
-  public static void checkState(
-      boolean b, @Nullable String errorMessageTemplate, long p1, long p2) {
+  public static void checkState(boolean b, String errorMessageTemplate, long p1, long p2) {
     if (!b) {
       throw new IllegalStateException(lenientFormat(errorMessageTemplate, p1, p2));
     }
@@ -790,7 +787,7 @@ public static void checkState(
    * @since 20.0 (varargs overload since 2.0)
    */
   public static void checkState(
-      boolean b, @Nullable String errorMessageTemplate, long p1, @Nullable Object p2) {
+      boolean b, String errorMessageTemplate, long p1, @CheckForNull Object p2) {
     if (!b) {
       throw new IllegalStateException(lenientFormat(errorMessageTemplate, p1, p2));
     }
@@ -805,7 +802,7 @@ public static void checkState(
    * @since 20.0 (varargs overload since 2.0)
    */
   public static void checkState(
-      boolean b, @Nullable String errorMessageTemplate, @Nullable Object p1, char p2) {
+      boolean b, String errorMessageTemplate, @CheckForNull Object p1, char p2) {
     if (!b) {
       throw new IllegalStateException(lenientFormat(errorMessageTemplate, p1, p2));
     }
@@ -820,7 +817,7 @@ public static void checkState(
    * @since 20.0 (varargs overload since 2.0)
    */
   public static void checkState(
-      boolean b, @Nullable String errorMessageTemplate, @Nullable Object p1, int p2) {
+      boolean b, String errorMessageTemplate, @CheckForNull Object p1, int p2) {
     if (!b) {
       throw new IllegalStateException(lenientFormat(errorMessageTemplate, p1, p2));
     }
@@ -835,7 +832,7 @@ public static void checkState(
    * @since 20.0 (varargs overload since 2.0)
    */
   public static void checkState(
-      boolean b, @Nullable String errorMessageTemplate, @Nullable Object p1, long p2) {
+      boolean b, String errorMessageTemplate, @CheckForNull Object p1, long p2) {
     if (!b) {
       throw new IllegalStateException(lenientFormat(errorMessageTemplate, p1, p2));
     }
@@ -850,7 +847,7 @@ public static void checkState(
    * @since 20.0 (varargs overload since 2.0)
    */
   public static void checkState(
-      boolean b, @Nullable String errorMessageTemplate, @Nullable Object p1, @Nullable Object p2) {
+      boolean b, String errorMessageTemplate, @CheckForNull Object p1, @CheckForNull Object p2) {
     if (!b) {
       throw new IllegalStateException(lenientFormat(errorMessageTemplate, p1, p2));
     }
@@ -866,10 +863,10 @@ public static void checkState(
    */
   public static void checkState(
       boolean b,
-      @Nullable String errorMessageTemplate,
-      @Nullable Object p1,
-      @Nullable Object p2,
-      @Nullable Object p3) {
+      String errorMessageTemplate,
+      @CheckForNull Object p1,
+      @CheckForNull Object p2,
+      @CheckForNull Object p3) {
     if (!b) {
       throw new IllegalStateException(lenientFormat(errorMessageTemplate, p1, p2, p3));
     }
@@ -885,16 +882,30 @@ public static void checkState(
    */
   public static void checkState(
       boolean b,
-      @Nullable String errorMessageTemplate,
-      @Nullable Object p1,
-      @Nullable Object p2,
-      @Nullable Object p3,
-      @Nullable Object p4) {
+      String errorMessageTemplate,
+      @CheckForNull Object p1,
+      @CheckForNull Object p2,
+      @CheckForNull Object p3,
+      @CheckForNull Object p4) {
     if (!b) {
       throw new IllegalStateException(lenientFormat(errorMessageTemplate, p1, p2, p3, p4));
     }
   }
 
+  /*
+   * Preconditions.checkNotNull is *intended* for performing eager null checks on parameters that a
+   * nullness checker can already "prove" are non-null. That means that the first parameter to
+   * checkNotNull *should* be annotated to require it to be non-null.
+   *
+   * However, for a variety of reasons, Google developers have written a ton of code over the past
+   * decade that assumes that they can use checkNotNull for non-precondition checks. I had hoped to
+   * take a principled stand on this, but the amount of such code is simply overwhelming. To avoid
+   * creating a lot of compile errors that users would not find to be informative, we're giving in
+   * and allowing callers to pass arguments that a nullness checker believes could be null.
+   *
+   * We still encourage people to use requireNonNull over checkNotNull for non-precondition checks.
+   */
+
   /**
    * Ensures that an object reference passed as a parameter to the calling method is not null.
    *
@@ -905,7 +916,7 @@ public static void checkState(
    */
   @CanIgnoreReturnValue
   @Pure
-  public static <T extends @NonNull Object> T checkNotNull(T reference) {
+  public static <T> T checkNotNull(@CheckForNull T reference) {
     if (reference == null) {
       throw new NullPointerException();
     }
@@ -924,8 +935,7 @@ public static void checkState(
    */
   @CanIgnoreReturnValue
   @Pure
-  public static <T extends @NonNull Object> T checkNotNull(
-      T reference, @Nullable Object errorMessage) {
+  public static <T> T checkNotNull(@CheckForNull T reference, @CheckForNull Object errorMessage) {
     if (reference == null) {
       throw new NullPointerException(String.valueOf(errorMessage));
     }
@@ -949,10 +959,10 @@ public static void checkState(
    */
   @CanIgnoreReturnValue
   @Pure
-  public static <T extends @NonNull Object> T checkNotNull(
-      T reference,
-      @Nullable String errorMessageTemplate,
-      @Nullable Object @Nullable ... errorMessageArgs) {
+  public static <T> T checkNotNull(
+      @CheckForNull T reference,
+      String errorMessageTemplate,
+      @CheckForNull @Nullable Object... errorMessageArgs) {
     if (reference == null) {
       throw new NullPointerException(lenientFormat(errorMessageTemplate, errorMessageArgs));
     }
@@ -968,8 +978,7 @@ public static void checkState(
    */
   @CanIgnoreReturnValue
   @Pure
-  public static <T extends @NonNull Object> T checkNotNull(
-      T obj, @Nullable String errorMessageTemplate, char p1) {
+  public static <T> T checkNotNull(@CheckForNull T obj, String errorMessageTemplate, char p1) {
     if (obj == null) {
       throw new NullPointerException(lenientFormat(errorMessageTemplate, p1));
     }
@@ -985,8 +994,7 @@ public static void checkState(
    */
   @CanIgnoreReturnValue
   @Pure
-  public static <T extends @NonNull Object> T checkNotNull(
-      T obj, @Nullable String errorMessageTemplate, int p1) {
+  public static <T> T checkNotNull(@CheckForNull T obj, String errorMessageTemplate, int p1) {
     if (obj == null) {
       throw new NullPointerException(lenientFormat(errorMessageTemplate, p1));
     }
@@ -1002,8 +1010,7 @@ public static void checkState(
    */
   @CanIgnoreReturnValue
   @Pure
-  public static <T extends @NonNull Object> T checkNotNull(
-      T obj, @Nullable String errorMessageTemplate, long p1) {
+  public static <T> T checkNotNull(@CheckForNull T obj, String errorMessageTemplate, long p1) {
     if (obj == null) {
       throw new NullPointerException(lenientFormat(errorMessageTemplate, p1));
     }
@@ -1019,8 +1026,8 @@ public static void checkState(
    */
   @CanIgnoreReturnValue
   @Pure
-  public static <T extends @NonNull Object> T checkNotNull(
-      T obj, @Nullable String errorMessageTemplate, @Nullable Object p1) {
+  public static <T> T checkNotNull(
+      @CheckForNull T obj, String errorMessageTemplate, @CheckForNull Object p1) {
     if (obj == null) {
       throw new NullPointerException(lenientFormat(errorMessageTemplate, p1));
     }
@@ -1036,8 +1043,8 @@ public static void checkState(
    */
   @CanIgnoreReturnValue
   @Pure
-  public static <T extends @NonNull Object> T checkNotNull(
-      T obj, @Nullable String errorMessageTemplate, char p1, char p2) {
+  public static <T> T checkNotNull(
+      @CheckForNull T obj, String errorMessageTemplate, char p1, char p2) {
     if (obj == null) {
       throw new NullPointerException(lenientFormat(errorMessageTemplate, p1, p2));
     }
@@ -1053,8 +1060,8 @@ public static void checkState(
    */
   @CanIgnoreReturnValue
   @Pure
-  public static <T extends @NonNull Object> T checkNotNull(
-      T obj, @Nullable String errorMessageTemplate, char p1, int p2) {
+  public static <T> T checkNotNull(
+      @CheckForNull T obj, String errorMessageTemplate, char p1, int p2) {
     if (obj == null) {
       throw new NullPointerException(lenientFormat(errorMessageTemplate, p1, p2));
     }
@@ -1070,8 +1077,8 @@ public static void checkState(
    */
   @CanIgnoreReturnValue
   @Pure
-  public static <T extends @NonNull Object> T checkNotNull(
-      T obj, @Nullable String errorMessageTemplate, char p1, long p2) {
+  public static <T> T checkNotNull(
+      @CheckForNull T obj, String errorMessageTemplate, char p1, long p2) {
     if (obj == null) {
       throw new NullPointerException(lenientFormat(errorMessageTemplate, p1, p2));
     }
@@ -1087,8 +1094,8 @@ public static void checkState(
    */
   @CanIgnoreReturnValue
   @Pure
-  public static <T extends @NonNull Object> T checkNotNull(
-      T obj, @Nullable String errorMessageTemplate, char p1, @Nullable Object p2) {
+  public static <T> T checkNotNull(
+      @CheckForNull T obj, String errorMessageTemplate, char p1, @CheckForNull Object p2) {
     if (obj == null) {
       throw new NullPointerException(lenientFormat(errorMessageTemplate, p1, p2));
     }
@@ -1104,8 +1111,8 @@ public static void checkState(
    */
   @CanIgnoreReturnValue
   @Pure
-  public static <T extends @NonNull Object> T checkNotNull(
-      T obj, @Nullable String errorMessageTemplate, int p1, char p2) {
+  public static <T> T checkNotNull(
+      @CheckForNull T obj, String errorMessageTemplate, int p1, char p2) {
     if (obj == null) {
       throw new NullPointerException(lenientFormat(errorMessageTemplate, p1, p2));
     }
@@ -1121,8 +1128,8 @@ public static void checkState(
    */
   @CanIgnoreReturnValue
   @Pure
-  public static <T extends @NonNull Object> T checkNotNull(
-      T obj, @Nullable String errorMessageTemplate, int p1, int p2) {
+  public static <T> T checkNotNull(
+      @CheckForNull T obj, String errorMessageTemplate, int p1, int p2) {
     if (obj == null) {
       throw new NullPointerException(lenientFormat(errorMessageTemplate, p1, p2));
     }
@@ -1138,8 +1145,8 @@ public static void checkState(
    */
   @CanIgnoreReturnValue
   @Pure
-  public static <T extends @NonNull Object> T checkNotNull(
-      T obj, @Nullable String errorMessageTemplate, int p1, long p2) {
+  public static <T> T checkNotNull(
+      @CheckForNull T obj, String errorMessageTemplate, int p1, long p2) {
     if (obj == null) {
       throw new NullPointerException(lenientFormat(errorMessageTemplate, p1, p2));
     }
@@ -1155,8 +1162,8 @@ public static void checkState(
    */
   @CanIgnoreReturnValue
   @Pure
-  public static <T extends @NonNull Object> T checkNotNull(
-      T obj, @Nullable String errorMessageTemplate, int p1, @Nullable Object p2) {
+  public static <T> T checkNotNull(
+      @CheckForNull T obj, String errorMessageTemplate, int p1, @CheckForNull Object p2) {
     if (obj == null) {
       throw new NullPointerException(lenientFormat(errorMessageTemplate, p1, p2));
     }
@@ -1172,8 +1179,8 @@ public static void checkState(
    */
   @CanIgnoreReturnValue
   @Pure
-  public static <T extends @NonNull Object> T checkNotNull(
-      T obj, @Nullable String errorMessageTemplate, long p1, char p2) {
+  public static <T> T checkNotNull(
+      @CheckForNull T obj, String errorMessageTemplate, long p1, char p2) {
     if (obj == null) {
       throw new NullPointerException(lenientFormat(errorMessageTemplate, p1, p2));
     }
@@ -1189,8 +1196,8 @@ public static void checkState(
    */
   @CanIgnoreReturnValue
   @Pure
-  public static <T extends @NonNull Object> T checkNotNull(
-      T obj, @Nullable String errorMessageTemplate, long p1, int p2) {
+  public static <T> T checkNotNull(
+      @CheckForNull T obj, String errorMessageTemplate, long p1, int p2) {
     if (obj == null) {
       throw new NullPointerException(lenientFormat(errorMessageTemplate, p1, p2));
     }
@@ -1206,8 +1213,8 @@ public static void checkState(
    */
   @CanIgnoreReturnValue
   @Pure
-  public static <T extends @NonNull Object> T checkNotNull(
-      T obj, @Nullable String errorMessageTemplate, long p1, long p2) {
+  public static <T> T checkNotNull(
+      @CheckForNull T obj, String errorMessageTemplate, long p1, long p2) {
     if (obj == null) {
       throw new NullPointerException(lenientFormat(errorMessageTemplate, p1, p2));
     }
@@ -1223,8 +1230,8 @@ public static void checkState(
    */
   @CanIgnoreReturnValue
   @Pure
-  public static <T extends @NonNull Object> T checkNotNull(
-      T obj, @Nullable String errorMessageTemplate, long p1, @Nullable Object p2) {
+  public static <T> T checkNotNull(
+      @CheckForNull T obj, String errorMessageTemplate, long p1, @CheckForNull Object p2) {
     if (obj == null) {
       throw new NullPointerException(lenientFormat(errorMessageTemplate, p1, p2));
     }
@@ -1240,8 +1247,8 @@ public static void checkState(
    */
   @CanIgnoreReturnValue
   @Pure
-  public static <T extends @NonNull Object> T checkNotNull(
-      T obj, @Nullable String errorMessageTemplate, @Nullable Object p1, char p2) {
+  public static <T> T checkNotNull(
+      @CheckForNull T obj, String errorMessageTemplate, @CheckForNull Object p1, char p2) {
     if (obj == null) {
       throw new NullPointerException(lenientFormat(errorMessageTemplate, p1, p2));
     }
@@ -1257,8 +1264,8 @@ public static void checkState(
    */
   @CanIgnoreReturnValue
   @Pure
-  public static <T extends @NonNull Object> T checkNotNull(
-      T obj, @Nullable String errorMessageTemplate, @Nullable Object p1, int p2) {
+  public static <T> T checkNotNull(
+      @CheckForNull T obj, String errorMessageTemplate, @CheckForNull Object p1, int p2) {
     if (obj == null) {
       throw new NullPointerException(lenientFormat(errorMessageTemplate, p1, p2));
     }
@@ -1274,8 +1281,8 @@ public static void checkState(
    */
   @CanIgnoreReturnValue
   @Pure
-  public static <T extends @NonNull Object> T checkNotNull(
-      T obj, @Nullable String errorMessageTemplate, @Nullable Object p1, long p2) {
+  public static <T> T checkNotNull(
+      @CheckForNull T obj, String errorMessageTemplate, @CheckForNull Object p1, long p2) {
     if (obj == null) {
       throw new NullPointerException(lenientFormat(errorMessageTemplate, p1, p2));
     }
@@ -1291,8 +1298,11 @@ public static void checkState(
    */
   @CanIgnoreReturnValue
   @Pure
-  public static <T extends @NonNull Object> T checkNotNull(
-      T obj, @Nullable String errorMessageTemplate, @Nullable Object p1, @Nullable Object p2) {
+  public static <T> T checkNotNull(
+      @CheckForNull T obj,
+      String errorMessageTemplate,
+      @CheckForNull Object p1,
+      @CheckForNull Object p2) {
     if (obj == null) {
       throw new NullPointerException(lenientFormat(errorMessageTemplate, p1, p2));
     }
@@ -1308,12 +1318,12 @@ public static void checkState(
    */
   @CanIgnoreReturnValue
   @Pure
-  public static <T extends @NonNull Object> T checkNotNull(
-      T obj,
-      @Nullable String errorMessageTemplate,
-      @Nullable Object p1,
-      @Nullable Object p2,
-      @Nullable Object p3) {
+  public static <T> T checkNotNull(
+      @CheckForNull T obj,
+      String errorMessageTemplate,
+      @CheckForNull Object p1,
+      @CheckForNull Object p2,
+      @CheckForNull Object p3) {
     if (obj == null) {
       throw new NullPointerException(lenientFormat(errorMessageTemplate, p1, p2, p3));
     }
@@ -1329,13 +1339,13 @@ public static void checkState(
    */
   @CanIgnoreReturnValue
   @Pure
-  public static <T extends @NonNull Object> T checkNotNull(
-      T obj,
-      @Nullable String errorMessageTemplate,
-      @Nullable Object p1,
-      @Nullable Object p2,
-      @Nullable Object p3,
-      @Nullable Object p4) {
+  public static <T> T checkNotNull(
+      @CheckForNull T obj,
+      String errorMessageTemplate,
+      @CheckForNull Object p1,
+      @CheckForNull Object p2,
+      @CheckForNull Object p3,
+      @CheckForNull Object p4) {
     if (obj == null) {
       throw new NullPointerException(lenientFormat(errorMessageTemplate, p1, p2, p3, p4));
     }
@@ -1404,7 +1414,7 @@ public static void checkState(
     return index;
   }
 
-  private static String badElementIndex(int index, int size, @Nullable String desc) {
+  private static String badElementIndex(int index, int size, String desc) {
     if (index < 0) {
       return lenientFormat("%s (%s) must not be negative", desc, index);
     } else if (size < 0) {
@@ -1449,7 +1459,7 @@ private static String badElementIndex(int index, int size, @Nullable String desc
     return index;
   }
 
-  private static String badPositionIndex(int index, int size, @Nullable String desc) {
+  private static String badPositionIndex(int index, int size, String desc) {
     if (index < 0) {
       return lenientFormat("%s (%s) must not be negative", desc, index);
     } else if (size < 0) {
@@ -1488,21 +1498,4 @@ private static String badPositionIndexes(int start, int end, int size) {
     // end < start
     return lenientFormat("end index (%s) must not be less than start index (%s)", end, start);
   }
-
-  static {
-    try {
-      Java8Usage.performCheck();
-    } catch (Throwable underlying) {
-      Exception toLog =
-          new Exception(
-              "Guava will drop support for Java 7 in 2021. Please let us know if this will cause"
-                  + " you problems: https://github.com/google/guava/issues/5269",
-              underlying);
-      Logger.getLogger(Preconditions.class.getName())
-          .log(
-              WARNING,
-              "Java 7 compatibility warning: See https://github.com/google/guava/issues/5269",
-              toLog);
-    }
-  }
 }
diff --git a/guava/src/com/google/common/base/Predicate.java b/guava/src/com/google/common/base/Predicate.java
index ccfc2f31acc3..5aa88e761687 100644
--- a/guava/src/com/google/common/base/Predicate.java
+++ b/guava/src/com/google/common/base/Predicate.java
@@ -16,6 +16,7 @@
 
 import com.google.common.annotations.GwtCompatible;
 import com.google.errorprone.annotations.CanIgnoreReturnValue;
+import javax.annotation.CheckForNull;
 import org.checkerframework.checker.nullness.qual.Nullable;
 import org.checkerframework.dataflow.qual.Pure;
 import org.checkerframework.framework.qual.AnnotatedFor;
@@ -45,7 +46,8 @@
 @FunctionalInterface
 @GwtCompatible
 @AnnotatedFor({"nullness"})
-public interface Predicate<T> extends java.util.function.Predicate<T> {
+@ElementTypesAreNonnullByDefault
+public interface Predicate<T extends @Nullable Object> extends java.util.function.Predicate<T> {
   /**
    * Returns the result of applying this predicate to {@code input} (Java 8 users, see notes in the
    * class documentation above). This method is <i>generally expected</i>, but not absolutely
@@ -62,7 +64,7 @@ public interface Predicate<T> extends java.util.function.Predicate<T> {
    *     arguments
    */
   @CanIgnoreReturnValue
-  boolean apply(@Nullable T input);
+  boolean apply(@ParametricNullness T input);
 
   /**
    * Indicates whether another object is equal to this predicate.
@@ -76,10 +78,10 @@ public interface Predicate<T> extends java.util.function.Predicate<T> {
    */
   @Pure
   @Override
-  boolean equals(@Nullable Object object);
+  boolean equals(@CheckForNull Object object);
 
   @Override
-  default boolean test(@Nullable T input) {
+  default boolean test(@ParametricNullness T input) {
     return apply(input);
   }
 }
diff --git a/guava/src/com/google/common/base/Predicates.java b/guava/src/com/google/common/base/Predicates.java
index 7cb1a41a383b..dc2548ad6192 100644
--- a/guava/src/com/google/common/base/Predicates.java
+++ b/guava/src/com/google/common/base/Predicates.java
@@ -25,6 +25,7 @@
 import java.util.Collection;
 import java.util.List;
 import java.util.regex.Pattern;
+import javax.annotation.CheckForNull;
 import org.checkerframework.checker.nullness.qual.Nullable;
 import org.checkerframework.dataflow.qual.Pure;
 import org.checkerframework.framework.qual.AnnotatedFor;
@@ -42,6 +43,7 @@
  */
 @AnnotatedFor({"nullness"})
 @GwtCompatible(emulated = true)
+@ElementTypesAreNonnullByDefault
 public final class Predicates {
   private Predicates() {}
 
@@ -50,13 +52,13 @@ private Predicates() {}
 
   /** Returns a predicate that always evaluates to {@code true}. */
   @GwtCompatible(serializable = true)
-  public static <T> Predicate<T> alwaysTrue() {
+  public static <T extends @Nullable Object> Predicate<T> alwaysTrue() {
     return ObjectPredicate.ALWAYS_TRUE.withNarrowedType();
   }
 
   /** Returns a predicate that always evaluates to {@code false}. */
   @GwtCompatible(serializable = true)
-  public static <T> Predicate<T> alwaysFalse() {
+  public static <T extends @Nullable Object> Predicate<T> alwaysFalse() {
     return ObjectPredicate.ALWAYS_FALSE.withNarrowedType();
   }
 
@@ -65,7 +67,7 @@ public static <T> Predicate<T> alwaysFalse() {
    * null.
    */
   @GwtCompatible(serializable = true)
-  public static <T> Predicate<T> isNull() {
+  public static <T extends @Nullable Object> Predicate<T> isNull() {
     return ObjectPredicate.IS_NULL.withNarrowedType();
   }
 
@@ -74,7 +76,7 @@ public static <T> Predicate<T> isNull() {
    * null.
    */
   @GwtCompatible(serializable = true)
-  public static <T> Predicate<T> notNull() {
+  public static <T extends @Nullable Object> Predicate<T> notNull() {
     return ObjectPredicate.NOT_NULL.withNarrowedType();
   }
 
@@ -82,8 +84,8 @@ public static <T> Predicate<T> notNull() {
    * Returns a predicate that evaluates to {@code true} if the given predicate evaluates to {@code
    * false}.
    */
-  public static <T> Predicate<T> not(Predicate<T> predicate) {
-    return new NotPredicate<T>(predicate);
+  public static <T extends @Nullable Object> Predicate<T> not(Predicate<T> predicate) {
+    return new NotPredicate<>(predicate);
   }
 
   /**
@@ -93,8 +95,9 @@ public static <T> Predicate<T> not(Predicate<T> predicate) {
    * changes to it won't alter the behavior of this predicate. If {@code components} is empty, the
    * returned predicate will always evaluate to {@code true}.
    */
-  public static <T> Predicate<T> and(Iterable<? extends Predicate<? super T>> components) {
-    return new AndPredicate<T>(defensiveCopy(components));
+  public static <T extends @Nullable Object> Predicate<T> and(
+      Iterable<? extends Predicate<? super T>> components) {
+    return new AndPredicate<>(defensiveCopy(components));
   }
 
   /**
@@ -105,7 +108,7 @@ public static <T> Predicate<T> and(Iterable<? extends Predicate<? super T>> comp
    * returned predicate will always evaluate to {@code true}.
    */
   @SafeVarargs
-  public static <T> Predicate<T> and(Predicate<? super T>... components) {
+  public static <T extends @Nullable Object> Predicate<T> and(Predicate<? super T>... components) {
     return new AndPredicate<T>(defensiveCopy(components));
   }
 
@@ -114,8 +117,9 @@ public static <T> Predicate<T> and(Predicate<? super T>... components) {
    * true}. The components are evaluated in order, and evaluation will be "short-circuited" as soon
    * as a false predicate is found.
    */
-  public static <T> Predicate<T> and(Predicate<? super T> first, Predicate<? super T> second) {
-    return new AndPredicate<T>(Predicates.<T>asList(checkNotNull(first), checkNotNull(second)));
+  public static <T extends @Nullable Object> Predicate<T> and(
+      Predicate<? super T> first, Predicate<? super T> second) {
+    return new AndPredicate<>(Predicates.<T>asList(checkNotNull(first), checkNotNull(second)));
   }
 
   /**
@@ -125,8 +129,9 @@ public static <T> Predicate<T> and(Predicate<? super T> first, Predicate<? super
    * changes to it won't alter the behavior of this predicate. If {@code components} is empty, the
    * returned predicate will always evaluate to {@code false}.
    */
-  public static <T> Predicate<T> or(Iterable<? extends Predicate<? super T>> components) {
-    return new OrPredicate<T>(defensiveCopy(components));
+  public static <T extends @Nullable Object> Predicate<T> or(
+      Iterable<? extends Predicate<? super T>> components) {
+    return new OrPredicate<>(defensiveCopy(components));
   }
 
   /**
@@ -137,7 +142,7 @@ public static <T> Predicate<T> or(Iterable<? extends Predicate<? super T>> compo
    * returned predicate will always evaluate to {@code false}.
    */
   @SafeVarargs
-  public static <T> Predicate<T> or(Predicate<? super T>... components) {
+  public static <T extends @Nullable Object> Predicate<T> or(Predicate<? super T>... components) {
     return new OrPredicate<T>(defensiveCopy(components));
   }
 
@@ -146,16 +151,19 @@ public static <T> Predicate<T> or(Predicate<? super T>... components) {
    * {@code true}. The components are evaluated in order, and evaluation will be "short-circuited"
    * as soon as a true predicate is found.
    */
-  public static <T> Predicate<T> or(Predicate<? super T> first, Predicate<? super T> second) {
-    return new OrPredicate<T>(Predicates.<T>asList(checkNotNull(first), checkNotNull(second)));
+  public static <T extends @Nullable Object> Predicate<T> or(
+      Predicate<? super T> first, Predicate<? super T> second) {
+    return new OrPredicate<>(Predicates.<T>asList(checkNotNull(first), checkNotNull(second)));
   }
 
   /**
    * Returns a predicate that evaluates to {@code true} if the object being tested {@code equals()}
    * the given target or both are null.
    */
-  public static <T> Predicate<T> equalTo(@Nullable T target) {
-    return (target == null) ? Predicates.<T>isNull() : new IsEqualToPredicate<T>(target);
+  public static <T extends @Nullable Object> Predicate<T> equalTo(@ParametricNullness T target) {
+    return (target == null)
+        ? Predicates.<T>isNull()
+        : new IsEqualToPredicate(target).withNarrowedType();
   }
 
   /**
@@ -172,8 +180,8 @@ public static <T> Predicate<T> equalTo(@Nullable T target) {
    * instances {@code Lists.newArrayList(1)} and {@code Arrays.asList(1)}.
    */
   @GwtIncompatible // Class.isInstance
-  public static Predicate<Object> instanceOf(Class<?> clazz) {
-    return new InstanceOfPredicate(clazz);
+  public static <T extends @Nullable Object> Predicate<T> instanceOf(Class<?> clazz) {
+    return new InstanceOfPredicate<>(clazz);
   }
 
   /**
@@ -207,8 +215,8 @@ public static Predicate<Class<?>> subtypeOf(Class<?> clazz) {
    *
    * @param target the collection that may contain the function input
    */
-  public static <T> Predicate<T> in(Collection<? extends T> target) {
-    return new InPredicate<T>(target);
+  public static <T extends @Nullable Object> Predicate<T> in(Collection<? extends T> target) {
+    return new InPredicate<>(target);
   }
 
   /**
@@ -217,7 +225,7 @@ public static <T> Predicate<T> in(Collection<? extends T> target) {
    *
    * @return the composition of the provided function and predicate
    */
-  public static <A, B> Predicate<A> compose(
+  public static <A extends @Nullable Object, B extends @Nullable Object> Predicate<A> compose(
       Predicate<B> predicate, Function<A, ? extends B> function) {
     return new CompositionPredicate<>(predicate, function);
   }
@@ -250,11 +258,11 @@ public static Predicate<CharSequence> contains(Pattern pattern) {
   // End public API, begin private implementation classes.
 
   // Package private for GWT serialization.
-  enum ObjectPredicate implements Predicate<Object> {
+  enum ObjectPredicate implements Predicate<@Nullable Object> {
     /** @see Predicates#alwaysTrue() */
     ALWAYS_TRUE {
       @Override
-      public boolean apply(@Nullable Object o) {
+      public boolean apply(@CheckForNull Object o) {
         return true;
       }
 
@@ -266,7 +274,7 @@ public String toString() {
     /** @see Predicates#alwaysFalse() */
     ALWAYS_FALSE {
       @Override
-      public boolean apply(@Nullable Object o) {
+      public boolean apply(@CheckForNull Object o) {
         return false;
       }
 
@@ -278,7 +286,7 @@ public String toString() {
     /** @see Predicates#isNull() */
     IS_NULL {
       @Override
-      public boolean apply(@Nullable Object o) {
+      public boolean apply(@CheckForNull Object o) {
         return o == null;
       }
 
@@ -290,7 +298,7 @@ public String toString() {
     /** @see Predicates#notNull() */
     NOT_NULL {
       @Override
-      public boolean apply(@Nullable Object o) {
+      public boolean apply(@CheckForNull Object o) {
         return o != null;
       }
 
@@ -301,13 +309,14 @@ public String toString() {
     };
 
     @SuppressWarnings("unchecked") // safe contravariant cast
-    <T> Predicate<T> withNarrowedType() {
+    <T extends @Nullable Object> Predicate<T> withNarrowedType() {
       return (Predicate<T>) this;
     }
   }
 
   /** @see Predicates#not(Predicate) */
-  private static class NotPredicate<T> implements Predicate<T>, Serializable {
+  private static class NotPredicate<T extends @Nullable Object>
+      implements Predicate<T>, Serializable {
     final Predicate<T> predicate;
 
     NotPredicate(Predicate<T> predicate) {
@@ -315,7 +324,7 @@ private static class NotPredicate<T> implements Predicate<T>, Serializable {
     }
 
     @Override
-    public boolean apply(@Nullable T t) {
+    public boolean apply(@ParametricNullness T t) {
       return !predicate.apply(t);
     }
 
@@ -327,7 +336,7 @@ public int hashCode() {
 
     @Pure
     @Override
-    public boolean equals(@Nullable Object obj) {
+    public boolean equals(@CheckForNull Object obj) {
       if (obj instanceof NotPredicate) {
         NotPredicate<?> that = (NotPredicate<?>) obj;
         return predicate.equals(that.predicate);
@@ -345,7 +354,8 @@ public String toString() {
   }
 
   /** @see Predicates#and(Iterable) */
-  private static class AndPredicate<T> implements Predicate<T>, Serializable {
+  private static class AndPredicate<T extends @Nullable Object>
+      implements Predicate<T>, Serializable {
     private final List<? extends Predicate<? super T>> components;
 
     private AndPredicate(List<? extends Predicate<? super T>> components) {
@@ -353,7 +363,7 @@ private AndPredicate(List<? extends Predicate<? super T>> components) {
     }
 
     @Override
-    public boolean apply(@Nullable T t) {
+    public boolean apply(@ParametricNullness T t) {
       // Avoid using the Iterator to avoid generating garbage (issue 820).
       for (int i = 0; i < components.size(); i++) {
         if (!components.get(i).apply(t)) {
@@ -372,7 +382,7 @@ public int hashCode() {
 
     @Pure
     @Override
-    public boolean equals(@Nullable Object obj) {
+    public boolean equals(@CheckForNull Object obj) {
       if (obj instanceof AndPredicate) {
         AndPredicate<?> that = (AndPredicate<?>) obj;
         return components.equals(that.components);
@@ -390,7 +400,8 @@ public String toString() {
   }
 
   /** @see Predicates#or(Iterable) */
-  private static class OrPredicate<T> implements Predicate<T>, Serializable {
+  private static class OrPredicate<T extends @Nullable Object>
+      implements Predicate<T>, Serializable {
     private final List<? extends Predicate<? super T>> components;
 
     private OrPredicate(List<? extends Predicate<? super T>> components) {
@@ -398,7 +409,7 @@ private OrPredicate(List<? extends Predicate<? super T>> components) {
     }
 
     @Override
-    public boolean apply(@Nullable T t) {
+    public boolean apply(@ParametricNullness T t) {
       // Avoid using the Iterator to avoid generating garbage (issue 820).
       for (int i = 0; i < components.size(); i++) {
         if (components.get(i).apply(t)) {
@@ -417,7 +428,7 @@ public int hashCode() {
 
     @Pure
     @Override
-    public boolean equals(@Nullable Object obj) {
+    public boolean equals(@CheckForNull Object obj) {
       if (obj instanceof OrPredicate) {
         OrPredicate<?> that = (OrPredicate<?>) obj;
         return components.equals(that.components);
@@ -448,16 +459,16 @@ private static String toStringHelper(String methodName, Iterable<?> components)
   }
 
   /** @see Predicates#equalTo(Object) */
-  private static class IsEqualToPredicate<T> implements Predicate<T>, Serializable {
-    private final T target;
+  private static class IsEqualToPredicate implements Predicate<@Nullable Object>, Serializable {
+    private final Object target;
 
-    private IsEqualToPredicate(T target) {
+    private IsEqualToPredicate(Object target) {
       this.target = target;
     }
 
     @Override
-    public boolean apply(@Nullable T t) {
-      return target.equals(t);
+    public boolean apply(@CheckForNull Object o) {
+      return target.equals(o);
     }
 
     @Pure
@@ -468,9 +479,9 @@ public int hashCode() {
 
     @Pure
     @Override
-    public boolean equals(@Nullable Object obj) {
+    public boolean equals(@CheckForNull Object obj) {
       if (obj instanceof IsEqualToPredicate) {
-        IsEqualToPredicate<?> that = (IsEqualToPredicate<?>) obj;
+        IsEqualToPredicate that = (IsEqualToPredicate) obj;
         return target.equals(that.target);
       }
       return false;
@@ -483,11 +494,17 @@ public String toString() {
     }
 
     private static final long serialVersionUID = 0;
+
+    @SuppressWarnings("unchecked") // safe contravariant cast
+    <T extends @Nullable Object> Predicate<T> withNarrowedType() {
+      return (Predicate<T>) this;
+    }
   }
 
   /** @see Predicates#instanceOf(Class) */
   @GwtIncompatible // Class.isInstance
-  private static class InstanceOfPredicate implements Predicate<Object>, Serializable {
+  private static class InstanceOfPredicate<T extends @Nullable Object>
+      implements Predicate<T>, Serializable {
     private final Class<?> clazz;
 
     private InstanceOfPredicate(Class<?> clazz) {
@@ -495,7 +512,7 @@ private InstanceOfPredicate(Class<?> clazz) {
     }
 
     @Override
-    public boolean apply(@Nullable Object o) {
+    public boolean apply(@ParametricNullness T o) {
       return clazz.isInstance(o);
     }
 
@@ -507,9 +524,9 @@ public int hashCode() {
 
     @Pure
     @Override
-    public boolean equals(@Nullable Object obj) {
+    public boolean equals(@CheckForNull Object obj) {
       if (obj instanceof InstanceOfPredicate) {
-        InstanceOfPredicate that = (InstanceOfPredicate) obj;
+        InstanceOfPredicate<?> that = (InstanceOfPredicate<?>) obj;
         return clazz == that.clazz;
       }
       return false;
@@ -544,7 +561,7 @@ public int hashCode() {
     }
 
     @Override
-    public boolean equals(@Nullable Object obj) {
+    public boolean equals(@CheckForNull Object obj) {
       if (obj instanceof SubtypeOfPredicate) {
         SubtypeOfPredicate that = (SubtypeOfPredicate) obj;
         return clazz == that.clazz;
@@ -561,7 +578,8 @@ public String toString() {
   }
 
   /** @see Predicates#in(Collection) */
-  private static class InPredicate<T> implements Predicate<T>, Serializable {
+  private static class InPredicate<T extends @Nullable Object>
+      implements Predicate<T>, Serializable {
     private final Collection<?> target;
 
     private InPredicate(Collection<?> target) {
@@ -569,7 +587,7 @@ private InPredicate(Collection<?> target) {
     }
 
     @Override
-    public boolean apply(@Nullable T t) {
+    public boolean apply(@ParametricNullness T t) {
       try {
         return target.contains(t);
       } catch (NullPointerException | ClassCastException e) {
@@ -579,7 +597,7 @@ public boolean apply(@Nullable T t) {
 
     @Pure
     @Override
-    public boolean equals(@Nullable Object obj) {
+    public boolean equals(@CheckForNull Object obj) {
       if (obj instanceof InPredicate) {
         InPredicate<?> that = (InPredicate<?>) obj;
         return target.equals(that.target);
@@ -603,7 +621,8 @@ public String toString() {
   }
 
   /** @see Predicates#compose(Predicate, Function) */
-  private static class CompositionPredicate<A, B> implements Predicate<A>, Serializable {
+  private static class CompositionPredicate<A extends @Nullable Object, B extends @Nullable Object>
+      implements Predicate<A>, Serializable {
     final Predicate<B> p;
     final Function<A, ? extends B> f;
 
@@ -613,13 +632,13 @@ private CompositionPredicate(Predicate<B> p, Function<A, ? extends B> f) {
     }
 
     @Override
-    public boolean apply(@Nullable A a) {
+    public boolean apply(@ParametricNullness A a) {
       return p.apply(f.apply(a));
     }
 
     @Pure
     @Override
-    public boolean equals(@Nullable Object obj) {
+    public boolean equals(@CheckForNull Object obj) {
       if (obj instanceof CompositionPredicate) {
         CompositionPredicate<?, ?> that = (CompositionPredicate<?, ?>) obj;
         return f.equals(that.f) && p.equals(that.p);
@@ -666,7 +685,7 @@ public int hashCode() {
     }
 
     @Override
-    public boolean equals(@Nullable Object obj) {
+    public boolean equals(@CheckForNull Object obj) {
       if (obj instanceof ContainsPatternPredicate) {
         ContainsPatternPredicate that = (ContainsPatternPredicate) obj;
 
@@ -707,7 +726,7 @@ public String toString() {
     private static final long serialVersionUID = 0;
   }
 
-  private static <T> List<Predicate<? super T>> asList(
+  private static <T extends @Nullable Object> List<Predicate<? super T>> asList(
       Predicate<? super T> first, Predicate<? super T> second) {
     // TODO(kevinb): understand why we still get a warning despite @SafeVarargs!
     return Arrays.<Predicate<? super T>>asList(first, second);
@@ -718,7 +737,7 @@ private static <T> List<T> defensiveCopy(T... array) {
   }
 
   static <T> List<T> defensiveCopy(Iterable<T> iterable) {
-    ArrayList<T> list = new ArrayList<T>();
+    ArrayList<T> list = new ArrayList<>();
     for (T element : iterable) {
       list.add(checkNotNull(element));
     }
diff --git a/guava/src/com/google/common/base/Present.java b/guava/src/com/google/common/base/Present.java
index a25de826b89e..4e62da29e93b 100644
--- a/guava/src/com/google/common/base/Present.java
+++ b/guava/src/com/google/common/base/Present.java
@@ -19,10 +19,11 @@
 import com.google.common.annotations.GwtCompatible;
 import java.util.Collections;
 import java.util.Set;
-import org.checkerframework.checker.nullness.qual.Nullable;
+import javax.annotation.CheckForNull;
 
 /** Implementation of an {@link Optional} containing a reference. */
 @GwtCompatible
+@ElementTypesAreNonnullByDefault
 final class Present<T> extends Optional<T> {
   private final T reference;
 
@@ -70,14 +71,14 @@ public Set<T> asSet() {
 
   @Override
   public <V> Optional<V> transform(Function<? super T, V> function) {
-    return new Present<V>(
+    return new Present<>(
         checkNotNull(
             function.apply(reference),
             "the Function passed to Optional.transform() must not return null."));
   }
 
   @Override
-  public boolean equals(@Nullable Object object) {
+  public boolean equals(@CheckForNull Object object) {
     if (object instanceof Present) {
       Present<?> other = (Present<?>) object;
       return reference.equals(other.reference);
diff --git a/guava/src/com/google/common/base/SmallCharMatcher.java b/guava/src/com/google/common/base/SmallCharMatcher.java
index c0842c911b9f..6e97dc295333 100644
--- a/guava/src/com/google/common/base/SmallCharMatcher.java
+++ b/guava/src/com/google/common/base/SmallCharMatcher.java
@@ -29,6 +29,7 @@
  * @author Christopher Swenson
  */
 @GwtIncompatible // no precomputation is done in GWT
+@ElementTypesAreNonnullByDefault
 final class SmallCharMatcher extends NamedFastMatcher {
   static final int MAX_SIZE = 1023;
   private final char @MinLen(1)[] table;
@@ -73,7 +74,6 @@ private boolean checkFilter(int c) {
    * can hold setSize elements with the desired load factor.
    */
   @VisibleForTesting
-  @SuppressWarnings("lowerbound:assignment.type.incompatible") // bit operations
   static @Positive int chooseTableSize(@IntRange(from = 0, to = Character.MAX_VALUE) int setSize) {
     if (setSize == 1) {
       return 2;
@@ -141,7 +141,6 @@ public boolean matches(char c) {
   }
 
   @Override
-  @SuppressWarnings("lowerbound:argument.type.incompatible") // https://github.com/kelloggm/checker-framework/issues/192 char should be @NonNegative
   void setBits(BitSet table) {
     if (containsZero) {
       table.set(0);
diff --git a/guava/src/com/google/common/base/Splitter.java b/guava/src/com/google/common/base/Splitter.java
index 5dc7272884b2..b9a7be2e6daa 100644
--- a/guava/src/com/google/common/base/Splitter.java
+++ b/guava/src/com/google/common/base/Splitter.java
@@ -29,6 +29,7 @@
 import java.util.regex.Pattern;
 import java.util.stream.Stream;
 import java.util.stream.StreamSupport;
+import javax.annotation.CheckForNull;
 
 import org.checkerframework.checker.index.qual.GTENegativeOne;
 import org.checkerframework.checker.index.qual.IndexOrHigh;
@@ -106,6 +107,7 @@
  * @since 1.0
  */
 @GwtCompatible(emulated = true)
+@ElementTypesAreNonnullByDefault
 public final class Splitter {
   private final CharMatcher trimmer;
   private final boolean omitEmptyStrings;
@@ -572,25 +574,21 @@ protected SplittingIterator(Splitter splitter, CharSequence toSplit) {
       this.toSplit = toSplit;
     }
 
+    @CheckForNull
     @Override
     @SuppressWarnings({
-      /*
-       * limit is always positive.
-       * When limit is not 1, then it can be safely decremented.
-       */
-      "lowerbound:unary.decrement.type.incompatible", // decrement Positive which != 1
       /*
        * At the start of the loop, whenever offset!=-1 also nextStart=-1
        * One of the following holds:
        * - offset == nextStart
        * - nextStart was not changed since the last iteration
        */
-      "lowerbound:assignment.type.incompatible", // variable!=-1 implies another variable !=-1
+      "lowerbound:assignment", // variable!=-1 implies another variable !=-1
       /*
        * offset is usually @LTEqLengthOf("toSplit")
        * offset > toSplit.length() can happen, but is immediately corrected to -1
        */
-      "upperbound:assignment.type.incompatible" // variable temporarily exceeds upper bound
+      "upperbound:assignment" // variable temporarily exceeds upper bound
     })
     protected String computeNext() {
       /*
diff --git a/guava/src/com/google/common/base/StandardSystemProperty.java b/guava/src/com/google/common/base/StandardSystemProperty.java
index a7e04229c05a..dc29792de782 100644
--- a/guava/src/com/google/common/base/StandardSystemProperty.java
+++ b/guava/src/com/google/common/base/StandardSystemProperty.java
@@ -15,7 +15,7 @@
 package com.google.common.base;
 
 import com.google.common.annotations.GwtIncompatible;
-import org.checkerframework.checker.nullness.qual.Nullable;
+import javax.annotation.CheckForNull;
 
 /**
  * Represents a {@linkplain System#getProperties() standard system property}.
@@ -24,6 +24,7 @@
  * @since 15.0
  */
 @GwtIncompatible // java.lang.System#getProperty
+@ElementTypesAreNonnullByDefault
 public enum StandardSystemProperty {
 
   /** Java Runtime Environment version. */
@@ -152,7 +153,8 @@ public String key() {
    *   <li>{@code jdk.module.*} (added in Java 9, optional)
    * </ul>
    */
-  public @Nullable String value() {
+  @CheckForNull
+  public String value() {
     return System.getProperty(key);
   }
 
diff --git a/guava/src/com/google/common/base/Stopwatch.java b/guava/src/com/google/common/base/Stopwatch.java
index e4cca1ffef35..9d5282d24a55 100644
--- a/guava/src/com/google/common/base/Stopwatch.java
+++ b/guava/src/com/google/common/base/Stopwatch.java
@@ -79,7 +79,7 @@
  * Stopwatch.createStarted(
  *      new Ticker() {
  *        public long read() {
- *          return android.os.SystemClock.elapsedRealtimeNanos();
+ *          return android.os.SystemClock.elapsedRealtimeNanos(); // requires API Level 17
  *        }
  *      });
  * }</pre>
@@ -89,6 +89,7 @@
  */
 @GwtCompatible(emulated = true)
 @SuppressWarnings("GoodTime") // lots of violations
+@ElementTypesAreNonnullByDefault
 public final class Stopwatch {
   private final Ticker ticker;
   private boolean isRunning;
diff --git a/guava/src/com/google/common/base/Strings.java b/guava/src/com/google/common/base/Strings.java
index 8d86b71cb1ef..7ac3abf8f2cd 100644
--- a/guava/src/com/google/common/base/Strings.java
+++ b/guava/src/com/google/common/base/Strings.java
@@ -20,7 +20,10 @@
 
 import com.google.common.annotations.GwtCompatible;
 import com.google.common.annotations.VisibleForTesting;
+import com.google.errorprone.annotations.InlineMe;
+import com.google.errorprone.annotations.InlineMeValidationDisabled;
 import java.util.logging.Logger;
+import javax.annotation.CheckForNull;
 import org.checkerframework.checker.index.qual.IndexOrHigh;
 import org.checkerframework.checker.index.qual.NonNegative;
 import org.checkerframework.checker.nullness.qual.EnsuresNonNullIf;
@@ -34,6 +37,7 @@
  * @since 3.0
  */
 @GwtCompatible
+@ElementTypesAreNonnullByDefault
 public final class Strings {
   private Strings() {}
 
@@ -43,7 +47,7 @@ private Strings() {}
    * @param string the string to test and possibly return
    * @return {@code string} itself if it is non-null; {@code ""} if it is null
    */
-  public static String nullToEmpty(@Nullable String string) {
+  public static String nullToEmpty(@CheckForNull String string) {
     return Platform.nullToEmpty(string);
   }
 
@@ -53,7 +57,8 @@ public static String nullToEmpty(@Nullable String string) {
    * @param string the string to test and possibly return
    * @return {@code string} itself if it is nonempty; {@code null} if it is empty or null
    */
-  public static @Nullable String emptyToNull(@Nullable String string) {
+  @CheckForNull
+  public static String emptyToNull(@CheckForNull String string) {
     return Platform.emptyToNull(string);
   }
 
@@ -68,8 +73,7 @@ public static String nullToEmpty(@Nullable String string) {
    * @param string a string reference to check
    * @return {@code true} if the string is null or is the empty string
    */
-  @EnsuresNonNullIf(expression = "#1", result = false)
-  public static boolean isNullOrEmpty(@Nullable String string) {
+  public static boolean isNullOrEmpty(@CheckForNull String string) {
     return Platform.stringIsNullOrEmpty(string);
   }
 
@@ -139,12 +143,16 @@ public static String padEnd(String string, int minLength, char padChar) {
    * Returns a string consisting of a specific number of concatenated copies of an input string. For
    * example, {@code repeat("hey", 3)} returns the string {@code "heyheyhey"}.
    *
+   * <p><b>Java 11+ users:</b> use {@code string.repeat(count)} instead.
+   *
    * @param string any non-null string
    * @param count the number of times to repeat it; a nonnegative integer
    * @return a string containing {@code string} repeated {@code count} times (the empty string if
    *     {@code count} is zero)
    * @throws IllegalArgumentException if {@code count} is negative
    */
+  @InlineMe(replacement = "string.repeat(count)")
+  @InlineMeValidationDisabled("Java 11+ API only")
   public static String repeat(String string, @NonNegative int count) {
     checkNotNull(string); // eager for GWT.
 
@@ -263,7 +271,7 @@ static boolean validSurrogatePairAt(CharSequence string, int index) {
    */
   // TODO(diamondm) consider using Arrays.toString() for array parameters
   public static String lenientFormat(
-      @Nullable String template, @Nullable Object @Nullable ... args) {
+      @CheckForNull String template, @CheckForNull @Nullable Object... args) {
     template = String.valueOf(template); // null -> "null"
 
     if (args == null) {
@@ -303,7 +311,7 @@ public static String lenientFormat(
     return builder.toString();
   }
 
-  private static String lenientToString(@Nullable Object o) {
+  private static String lenientToString(@CheckForNull Object o) {
     if (o == null) {
       return "null";
     }
diff --git a/guava/src/com/google/common/base/Supplier.java b/guava/src/com/google/common/base/Supplier.java
index aee1853f33fd..b0724803c200 100644
--- a/guava/src/com/google/common/base/Supplier.java
+++ b/guava/src/com/google/common/base/Supplier.java
@@ -16,6 +16,7 @@
 
 import com.google.common.annotations.GwtCompatible;
 import com.google.errorprone.annotations.CanIgnoreReturnValue;
+import org.checkerframework.checker.nullness.qual.Nullable;
 import org.checkerframework.framework.qual.AnnotatedFor;
 
 /**
@@ -39,7 +40,8 @@
 @AnnotatedFor({"nullness"})
 @GwtCompatible
 @FunctionalInterface
-public interface Supplier<T> extends java.util.function.Supplier<T> {
+@ElementTypesAreNonnullByDefault
+public interface Supplier<T extends @Nullable Object> extends java.util.function.Supplier<T> {
   /**
    * Retrieves an instance of the appropriate type. The returned object may or may not be a new
    * instance, depending on the implementation.
@@ -48,5 +50,6 @@ public interface Supplier<T> extends java.util.function.Supplier<T> {
    */
   @CanIgnoreReturnValue
   @Override
+  @ParametricNullness
   T get();
 }
diff --git a/guava/src/com/google/common/base/Suppliers.java b/guava/src/com/google/common/base/Suppliers.java
index a62bf01dd753..4056f260f5f3 100644
--- a/guava/src/com/google/common/base/Suppliers.java
+++ b/guava/src/com/google/common/base/Suppliers.java
@@ -14,13 +14,16 @@
 
 package com.google.common.base;
 
+import static com.google.common.base.NullnessCasts.uncheckedCastNullableTToT;
 import static com.google.common.base.Preconditions.checkArgument;
 import static com.google.common.base.Preconditions.checkNotNull;
+import static java.util.Objects.requireNonNull;
 
 import com.google.common.annotations.GwtCompatible;
 import com.google.common.annotations.VisibleForTesting;
 import java.io.Serializable;
 import java.util.concurrent.TimeUnit;
+import javax.annotation.CheckForNull;
 import org.checkerframework.checker.nullness.qual.Nullable;
 import org.checkerframework.framework.qual.AnnotatedFor;
 
@@ -35,6 +38,7 @@
  */
 @AnnotatedFor({"nullness"})
 @GwtCompatible
+@ElementTypesAreNonnullByDefault
 public final class Suppliers {
   private Suppliers() {}
 
@@ -44,11 +48,13 @@ private Suppliers() {}
    * and then applying {@code function} to that value. Note that the resulting supplier will not
    * call {@code supplier} or invoke {@code function} until it is called.
    */
-  public static <F, T> Supplier<T> compose(Function<? super F, T> function, Supplier<F> supplier) {
+  public static <F extends @Nullable Object, T extends @Nullable Object> Supplier<T> compose(
+      Function<? super F, T> function, Supplier<F> supplier) {
     return new SupplierComposition<>(function, supplier);
   }
 
-  private static class SupplierComposition<F, T> implements Supplier<T>, Serializable {
+  private static class SupplierComposition<F extends @Nullable Object, T extends @Nullable Object>
+      implements Supplier<T>, Serializable {
     final Function<? super F, T> function;
     final Supplier<F> supplier;
 
@@ -58,12 +64,13 @@ private static class SupplierComposition<F, T> implements Supplier<T>, Serializa
     }
 
     @Override
+    @ParametricNullness
     public T get() {
       return function.apply(supplier.get());
     }
 
     @Override
-    public boolean equals(@Nullable Object obj) {
+    public boolean equals(@CheckForNull Object obj) {
       if (obj instanceof SupplierComposition) {
         SupplierComposition<?, ?> that = (SupplierComposition<?, ?>) obj;
         return function.equals(that.function) && supplier.equals(that.supplier);
@@ -100,7 +107,7 @@ public String toString() {
    * <p>If {@code delegate} is an instance created by an earlier call to {@code memoize}, it is
    * returned directly.
    */
-  public static <T> Supplier<T> memoize(Supplier<T> delegate) {
+  public static <T extends @Nullable Object> Supplier<T> memoize(Supplier<T> delegate) {
     if (delegate instanceof NonSerializableMemoizingSupplier
         || delegate instanceof MemoizingSupplier) {
       return delegate;
@@ -111,18 +118,19 @@ public static <T> Supplier<T> memoize(Supplier<T> delegate) {
   }
 
   @VisibleForTesting
-  static class MemoizingSupplier<T> implements Supplier<T>, Serializable {
+  static class MemoizingSupplier<T extends @Nullable Object> implements Supplier<T>, Serializable {
     final Supplier<T> delegate;
     transient volatile boolean initialized;
     // "value" does not need to be volatile; visibility piggy-backs
     // on volatile read of "initialized".
-    transient @Nullable T value;
+    @CheckForNull transient T value;
 
     MemoizingSupplier(Supplier<T> delegate) {
       this.delegate = checkNotNull(delegate);
     }
 
     @Override
+    @ParametricNullness
     public T get() {
       // A 2-field variant of Double Checked Locking.
       if (!initialized) {
@@ -135,7 +143,8 @@ public T get() {
           }
         }
       }
-      return value;
+      // This is safe because we checked `initialized.`
+      return uncheckedCastNullableTToT(value);
     }
 
     @Override
@@ -149,24 +158,31 @@ public String toString() {
   }
 
   @VisibleForTesting
-  static class NonSerializableMemoizingSupplier<T> implements Supplier<T> {
-    volatile Supplier<T> delegate;
+  static class NonSerializableMemoizingSupplier<T extends @Nullable Object> implements Supplier<T> {
+    @CheckForNull volatile Supplier<T> delegate;
     volatile boolean initialized;
     // "value" does not need to be volatile; visibility piggy-backs
     // on volatile read of "initialized".
-    @Nullable T value;
+    @CheckForNull T value;
 
     NonSerializableMemoizingSupplier(Supplier<T> delegate) {
       this.delegate = checkNotNull(delegate);
     }
 
     @Override
+    @ParametricNullness
     public T get() {
       // A 2-field variant of Double Checked Locking.
       if (!initialized) {
         synchronized (this) {
           if (!initialized) {
-            T t = delegate.get();
+            /*
+             * requireNonNull is safe because we read and write `delegate` under synchronization.
+             *
+             * TODO(cpovirk): To avoid having to check for null, replace `delegate` with a singleton
+             * `Supplier` that always throws an exception.
+             */
+            T t = requireNonNull(delegate).get();
             value = t;
             initialized = true;
             // Release the delegate to GC.
@@ -175,7 +191,8 @@ public T get() {
           }
         }
       }
-      return value;
+      // This is safe because we checked `initialized.`
+      return uncheckedCastNullableTToT(value);
     }
 
     @Override
@@ -209,17 +226,18 @@ public String toString() {
    * @since 2.0
    */
   @SuppressWarnings("GoodTime") // should accept a java.time.Duration
-  public static <T> Supplier<T> memoizeWithExpiration(
+  public static <T extends @Nullable Object> Supplier<T> memoizeWithExpiration(
       Supplier<T> delegate, long duration, TimeUnit unit) {
-    return new ExpiringMemoizingSupplier<T>(delegate, duration, unit);
+    return new ExpiringMemoizingSupplier<>(delegate, duration, unit);
   }
 
   @VisibleForTesting
   @SuppressWarnings("GoodTime") // lots of violations
-  static class ExpiringMemoizingSupplier<T> implements Supplier<T>, Serializable {
+  static class ExpiringMemoizingSupplier<T extends @Nullable Object>
+      implements Supplier<T>, Serializable {
     final Supplier<T> delegate;
     final long durationNanos;
-    transient volatile @Nullable T value;
+    @CheckForNull transient volatile T value;
     // The special value 0 means "not yet initialized".
     transient volatile long expirationNanos;
 
@@ -230,6 +248,7 @@ static class ExpiringMemoizingSupplier<T> implements Supplier<T>, Serializable {
     }
 
     @Override
+    @ParametricNullness
     public T get() {
       // Another variant of Double Checked Locking.
       //
@@ -252,7 +271,8 @@ public T get() {
           }
         }
       }
-      return value;
+      // This is safe because we checked `expirationNanos.`
+      return uncheckedCastNullableTToT(value);
     }
 
     @Override
@@ -266,24 +286,27 @@ public String toString() {
   }
 
   /** Returns a supplier that always supplies {@code instance}. */
-  public static <T> Supplier<T> ofInstance(@Nullable T instance) {
-    return new SupplierOfInstance<T>(instance);
+  public static <T extends @Nullable Object> Supplier<T> ofInstance(
+      @ParametricNullness T instance) {
+    return new SupplierOfInstance<>(instance);
   }
 
-  private static class SupplierOfInstance<T> implements Supplier<T>, Serializable {
-    final @Nullable T instance;
+  private static class SupplierOfInstance<T extends @Nullable Object>
+      implements Supplier<T>, Serializable {
+    @ParametricNullness final T instance;
 
-    SupplierOfInstance(@Nullable T instance) {
+    SupplierOfInstance(@ParametricNullness T instance) {
       this.instance = instance;
     }
 
     @Override
+    @ParametricNullness
     public T get() {
       return instance;
     }
 
     @Override
-    public boolean equals(@Nullable Object obj) {
+    public boolean equals(@CheckForNull Object obj) {
       if (obj instanceof SupplierOfInstance) {
         SupplierOfInstance<?> that = (SupplierOfInstance<?>) obj;
         return Objects.equal(instance, that.instance);
@@ -308,11 +331,13 @@ public String toString() {
    * Returns a supplier whose {@code get()} method synchronizes on {@code delegate} before calling
    * it, making it thread-safe.
    */
-  public static <T> Supplier<T> synchronizedSupplier(Supplier<T> delegate) {
-    return new ThreadSafeSupplier<T>(delegate);
+  public static <T extends @Nullable Object> Supplier<T> synchronizedSupplier(
+      Supplier<T> delegate) {
+    return new ThreadSafeSupplier<>(delegate);
   }
 
-  private static class ThreadSafeSupplier<T> implements Supplier<T>, Serializable {
+  private static class ThreadSafeSupplier<T extends @Nullable Object>
+      implements Supplier<T>, Serializable {
     final Supplier<T> delegate;
 
     ThreadSafeSupplier(Supplier<T> delegate) {
@@ -320,6 +345,7 @@ private static class ThreadSafeSupplier<T> implements Supplier<T>, Serializable
     }
 
     @Override
+    @ParametricNullness
     public T get() {
       synchronized (delegate) {
         return delegate.get();
@@ -342,20 +368,21 @@ public String toString() {
    *
    * @since 8.0
    */
-  public static <T> Function<Supplier<T>, T> supplierFunction() {
+  public static <T extends @Nullable Object> Function<Supplier<T>, T> supplierFunction() {
     @SuppressWarnings("unchecked") // implementation is "fully variant"
     SupplierFunction<T> sf = (SupplierFunction<T>) SupplierFunctionImpl.INSTANCE;
     return sf;
   }
 
-  private interface SupplierFunction<T> extends Function<Supplier<T>, T> {}
+  private interface SupplierFunction<T extends @Nullable Object> extends Function<Supplier<T>, T> {}
 
-  private enum SupplierFunctionImpl implements SupplierFunction<Object> {
+  private enum SupplierFunctionImpl implements SupplierFunction<@Nullable Object> {
     INSTANCE;
 
     // Note: This makes T a "pass-through type"
     @Override
-    public Object apply(Supplier<Object> input) {
+    @CheckForNull
+    public Object apply(Supplier<@Nullable Object> input) {
       return input.get();
     }
 
diff --git a/guava/src/com/google/common/base/Throwables.java b/guava/src/com/google/common/base/Throwables.java
index 35ccce1c12ad..6ef11eed0f52 100644
--- a/guava/src/com/google/common/base/Throwables.java
+++ b/guava/src/com/google/common/base/Throwables.java
@@ -17,8 +17,8 @@
 import static com.google.common.base.Preconditions.checkNotNull;
 import static java.util.Arrays.asList;
 import static java.util.Collections.unmodifiableList;
+import static java.util.Objects.requireNonNull;
 
-import com.google.common.annotations.Beta;
 import com.google.common.annotations.GwtCompatible;
 import com.google.common.annotations.GwtIncompatible;
 import com.google.common.annotations.VisibleForTesting;
@@ -32,6 +32,7 @@
 import java.util.ArrayList;
 import java.util.Collections;
 import java.util.List;
+import javax.annotation.CheckForNull;
 import org.checkerframework.checker.index.qual.NonNegative;
 import org.checkerframework.checker.nullness.qual.Nullable;
 
@@ -46,6 +47,7 @@
  * @since 1.0
  */
 @GwtCompatible(emulated = true)
+@ElementTypesAreNonnullByDefault
 public final class Throwables {
   private Throwables() {}
 
@@ -100,7 +102,7 @@ public static <X extends Throwable> void throwIfInstanceOf(
   @Deprecated
   @GwtIncompatible // throwIfInstanceOf
   public static <X extends Throwable> void propagateIfInstanceOf(
-      @Nullable Throwable throwable, Class<X> declaredType) throws X {
+      @CheckForNull Throwable throwable, Class<X> declaredType) throws X {
     if (throwable != null) {
       throwIfInstanceOf(throwable, declaredType);
     }
@@ -155,7 +157,7 @@ public static void throwIfUnchecked(Throwable throwable) {
    */
   @Deprecated
   @GwtIncompatible
-  public static void propagateIfPossible(@Nullable Throwable throwable) {
+  public static void propagateIfPossible(@CheckForNull Throwable throwable) {
     if (throwable != null) {
       throwIfUnchecked(throwable);
     }
@@ -181,7 +183,7 @@ public static void propagateIfPossible(@Nullable Throwable throwable) {
    */
   @GwtIncompatible // propagateIfInstanceOf
   public static <X extends Throwable> void propagateIfPossible(
-      @Nullable Throwable throwable, Class<X> declaredType) throws X {
+      @CheckForNull Throwable throwable, Class<X> declaredType) throws X {
     propagateIfInstanceOf(throwable, declaredType);
     propagateIfPossible(throwable);
   }
@@ -199,7 +201,7 @@ public static <X extends Throwable> void propagateIfPossible(
    */
   @GwtIncompatible // propagateIfInstanceOf
   public static <X1 extends Throwable, X2 extends Throwable> void propagateIfPossible(
-      @Nullable Throwable throwable, Class<X1> declaredType1, Class<X2> declaredType2)
+      @CheckForNull Throwable throwable, Class<X1> declaredType1, Class<X2> declaredType2)
       throws X1, X2 {
     checkNotNull(declaredType2);
     propagateIfInstanceOf(throwable, declaredType1);
@@ -289,7 +291,6 @@ public static Throwable getRootCause(Throwable throwable) {
    * @return an unmodifiable list containing the cause chain starting with {@code throwable}
    * @throws IllegalArgumentException if there is a loop in the causal chain
    */
-  @Beta // TODO(kevinb): decide best return type
   public static List<Throwable> getCausalChain(Throwable throwable) {
     checkNotNull(throwable);
     List<Throwable> causes = new ArrayList<>(4);
@@ -329,8 +330,8 @@ public static List<Throwable> getCausalChain(Throwable throwable) {
    *     ClassCastException}'s cause is {@code throwable}.
    * @since 22.0
    */
-  @Beta
   @GwtIncompatible // Class.cast(Object)
+  @CheckForNull
   public static <X extends Throwable> X getCauseAs(
       Throwable throwable, Class<X> expectedCauseType) {
     try {
@@ -380,11 +381,12 @@ public static String getStackTraceAsString(Throwable throwable) {
    * exception's creation.
    *
    * @since 19.0
+   * @deprecated This method is equivalent to {@link Throwable#getStackTrace()} on JDK versions past
+   *     JDK 8 and on all Android versions. Use {@link Throwable#getStackTrace()} directly, or where
+   *     possible use the {@code java.lang.StackWalker.walk} method introduced in JDK 9.
    */
-  // TODO(cpovirk): Say something about the possibility that List access could fail at runtime?
-  @Beta
+  @Deprecated
   @GwtIncompatible // lazyStackTraceIsLazy, jlaStackTrace
-  // TODO(cpovirk): Consider making this available under GWT (slow implementation only).
   public static List<StackTraceElement> lazyStackTrace(Throwable throwable) {
     return lazyStackTraceIsLazy()
         ? jlaStackTrace(throwable)
@@ -396,15 +398,17 @@ public static List<StackTraceElement> lazyStackTrace(Throwable throwable) {
    * documentation.
    *
    * @since 19.0
+   * @deprecated This method always returns false on JDK versions past JDK 8 and on all Android
+   *     versions.
    */
-  @Beta
+  @Deprecated
   @GwtIncompatible // getStackTraceElementMethod
   public static boolean lazyStackTraceIsLazy() {
     return getStackTraceElementMethod != null && getStackTraceDepthMethod != null;
   }
 
   @GwtIncompatible // invokeAccessibleNonThrowingMethod
-  private static List<StackTraceElement> jlaStackTrace(final Throwable t) {
+  private static List<StackTraceElement> jlaStackTrace(Throwable t) {
     checkNotNull(t);
     /*
      * TODO(cpovirk): Consider optimizing iterator() to catch IOOBE instead of doing bounds checks.
@@ -413,15 +417,22 @@ private static List<StackTraceElement> jlaStackTrace(final Throwable t) {
      * AOSP grief.
      */
     return new AbstractList<StackTraceElement>() {
+      /*
+       * The following requireNonNull calls are safe because we use jlaStackTrace() only if
+       * lazyStackTraceIsLazy() returns true.
+       */
       @Override
       public StackTraceElement get(int n) {
         return (StackTraceElement)
-            invokeAccessibleNonThrowingMethod(getStackTraceElementMethod, jla, t, n);
+            invokeAccessibleNonThrowingMethod(
+                requireNonNull(getStackTraceElementMethod), requireNonNull(jla), t, n);
       }
 
       @Override
       public @NonNegative int size() {
-        return (Integer) invokeAccessibleNonThrowingMethod(getStackTraceDepthMethod, jla, t);
+        return (Integer)
+            invokeAccessibleNonThrowingMethod(
+                requireNonNull(getStackTraceDepthMethod), requireNonNull(jla), t);
       }
     };
   }
@@ -449,30 +460,32 @@ private static Object invokeAccessibleNonThrowingMethod(
 
   /** Access to some fancy internal JVM internals. */
   @GwtIncompatible // java.lang.reflect
-  private static final @Nullable Object jla = getJLA();
+  @CheckForNull
+  private static final Object jla = getJLA();
 
   /**
    * The "getStackTraceElementMethod" method, only available on some JDKs so we use reflection to
    * find it when available. When this is null, use the slow way.
    */
   @GwtIncompatible // java.lang.reflect
-  private static final @Nullable Method getStackTraceElementMethod =
-      (jla == null) ? null : getGetMethod();
+  @CheckForNull
+  private static final Method getStackTraceElementMethod = (jla == null) ? null : getGetMethod();
 
   /**
    * The "getStackTraceDepth" method, only available on some JDKs so we use reflection to find it
    * when available. When this is null, use the slow way.
    */
   @GwtIncompatible // java.lang.reflect
-  private static final @Nullable Method getStackTraceDepthMethod =
-      (jla == null) ? null : getSizeMethod();
+  @CheckForNull
+  private static final Method getStackTraceDepthMethod = (jla == null) ? null : getSizeMethod(jla);
 
   /**
    * Returns the JavaLangAccess class that is present in all Sun JDKs. It is not allowed in
    * AppEngine, and not present in non-Sun JDKs.
    */
   @GwtIncompatible // java.lang.reflect
-  private static @Nullable Object getJLA() {
+  @CheckForNull
+  private static Object getJLA() {
     try {
       /*
        * We load sun.misc.* classes using reflection since Android doesn't support these classes and
@@ -497,7 +510,8 @@ private static Object invokeAccessibleNonThrowingMethod(
    * method cannot be found (it is only to be found in fairly recent JDKs).
    */
   @GwtIncompatible // java.lang.reflect
-  private static @Nullable Method getGetMethod() {
+  @CheckForNull
+  private static Method getGetMethod() {
     return getJlaMethod("getStackTraceElement", Throwable.class, int.class);
   }
 
@@ -511,13 +525,14 @@ private static Object invokeAccessibleNonThrowingMethod(
    * UnsupportedOperationException</a>.
    */
   @GwtIncompatible // java.lang.reflect
-  private static @Nullable Method getSizeMethod() {
+  @CheckForNull
+  private static Method getSizeMethod(Object jla) {
     try {
       Method getStackTraceDepth = getJlaMethod("getStackTraceDepth", Throwable.class);
       if (getStackTraceDepth == null) {
         return null;
       }
-      getStackTraceDepth.invoke(getJLA(), new Throwable());
+      getStackTraceDepth.invoke(jla, new Throwable());
       return getStackTraceDepth;
     } catch (UnsupportedOperationException | IllegalAccessException | InvocationTargetException e) {
       return null;
@@ -525,8 +540,8 @@ private static Object invokeAccessibleNonThrowingMethod(
   }
 
   @GwtIncompatible // java.lang.reflect
-  private static @Nullable Method getJlaMethod(String name, Class<?>... parameterTypes)
-      throws ThreadDeath {
+  @CheckForNull
+  private static Method getJlaMethod(String name, Class<?>... parameterTypes) throws ThreadDeath {
     try {
       return Class.forName(JAVA_LANG_ACCESS_CLASSNAME, false, null).getMethod(name, parameterTypes);
     } catch (ThreadDeath death) {
diff --git a/guava/src/com/google/common/base/Ticker.java b/guava/src/com/google/common/base/Ticker.java
index a53883b46ed7..d898735c028f 100644
--- a/guava/src/com/google/common/base/Ticker.java
+++ b/guava/src/com/google/common/base/Ticker.java
@@ -28,6 +28,7 @@
  *     source-compatible</a> since 9.0)
  */
 @GwtCompatible
+@ElementTypesAreNonnullByDefault
 public abstract class Ticker {
   /** Constructor for use by subclasses. */
   protected Ticker() {}
diff --git a/guava/src/com/google/common/base/Utf8.java b/guava/src/com/google/common/base/Utf8.java
index 578e26fcf252..b8087be6990f 100644
--- a/guava/src/com/google/common/base/Utf8.java
+++ b/guava/src/com/google/common/base/Utf8.java
@@ -41,6 +41,7 @@
  */
 @Beta
 @GwtCompatible(emulated = true)
+@ElementTypesAreNonnullByDefault
 public final class Utf8 {
   /**
    * Returns the number of bytes in the UTF-8-encoded form of {@code sequence}. For a string, this
@@ -51,7 +52,7 @@ public final class Utf8 {
    *     surrogates)
    */
   @SuppressWarnings({
-    "lowerbound:compound.assignment.type.incompatible", // unsigned right shift on int
+    "lowerbound:compound.assignment", // unsigned right shift on int
   })
   public static @NonNegative int encodedLength(CharSequence sequence) {
     // Warning to maintainers: this implementation is highly optimized.
@@ -83,7 +84,7 @@ public final class Utf8 {
     return utf8Length;
   }
   @SuppressWarnings({
-    "lowerbound:compound.assignment.type.incompatible", // unsigned right shift on int
+    "lowerbound:compound.assignment", // unsigned right shift on int
   })
   private static @NonNegative int encodedLengthGeneral(CharSequence sequence, @NonNegative/*!IndexFor("#1")*/ int start) {
     int utf16Length = sequence.length();
@@ -143,8 +144,9 @@ public static boolean isWellFormed(byte[] bytes, @IndexOrHigh("#1") int off, @No
   }
 
   @SuppressWarnings({
-    "cast.unsafe", // https://github.com/kelloggm/checker-framework/issues/149
-    "upperbound:unary.increment.type.incompatible", "upperbound:array.access.unsafe.high" // https://github.com/kelloggm/checker-framework/issues/158
+    "value:cast.unsafe", // https://github.com/kelloggm/checker-framework/issues/149
+    "upperbound:unary.increment",
+    "upperbound:array.access.unsafe.high" // https://github.com/kelloggm/checker-framework/issues/158
   })
   private static boolean isWellFormedSlowPath(byte[] bytes, @IndexOrHigh("#1") int off, @IndexOrHigh("#1") int end) {
     @IndexOrHigh("bytes") int index = off;
diff --git a/guava/src/com/google/common/base/Verify.java b/guava/src/com/google/common/base/Verify.java
index 08a4928f5c6e..3e99cd8f395c 100644
--- a/guava/src/com/google/common/base/Verify.java
+++ b/guava/src/com/google/common/base/Verify.java
@@ -18,6 +18,7 @@
 
 import com.google.common.annotations.GwtCompatible;
 import com.google.errorprone.annotations.CanIgnoreReturnValue;
+import javax.annotation.CheckForNull;
 import org.checkerframework.checker.nullness.qual.NonNull;
 import org.checkerframework.checker.nullness.qual.Nullable;
 
@@ -88,6 +89,7 @@
  * @since 17.0
  */
 @GwtCompatible
+@ElementTypesAreNonnullByDefault
 public final class Verify {
   /**
    * Ensures that {@code expression} is {@code true}, throwing a {@code VerifyException} with no
@@ -119,8 +121,8 @@ public static void verify(boolean expression) {
    */
   public static void verify(
       boolean expression,
-      @Nullable String errorMessageTemplate,
-      @Nullable Object @Nullable ... errorMessageArgs) {
+      String errorMessageTemplate,
+      @CheckForNull @Nullable Object... errorMessageArgs) {
     if (!expression) {
       throw new VerifyException(lenientFormat(errorMessageTemplate, errorMessageArgs));
     }
@@ -134,7 +136,7 @@ public static void verify(
    *
    * @since 23.1 (varargs overload since 17.0)
    */
-  public static void verify(boolean expression, @Nullable String errorMessageTemplate, char p1) {
+  public static void verify(boolean expression, String errorMessageTemplate, char p1) {
     if (!expression) {
       throw new VerifyException(lenientFormat(errorMessageTemplate, p1));
     }
@@ -148,7 +150,7 @@ public static void verify(boolean expression, @Nullable String errorMessageTempl
    *
    * @since 23.1 (varargs overload since 17.0)
    */
-  public static void verify(boolean expression, @Nullable String errorMessageTemplate, int p1) {
+  public static void verify(boolean expression, String errorMessageTemplate, int p1) {
     if (!expression) {
       throw new VerifyException(lenientFormat(errorMessageTemplate, p1));
     }
@@ -162,7 +164,7 @@ public static void verify(boolean expression, @Nullable String errorMessageTempl
    *
    * @since 23.1 (varargs overload since 17.0)
    */
-  public static void verify(boolean expression, @Nullable String errorMessageTemplate, long p1) {
+  public static void verify(boolean expression, String errorMessageTemplate, long p1) {
     if (!expression) {
       throw new VerifyException(lenientFormat(errorMessageTemplate, p1));
     }
@@ -177,7 +179,7 @@ public static void verify(boolean expression, @Nullable String errorMessageTempl
    * @since 23.1 (varargs overload since 17.0)
    */
   public static void verify(
-      boolean expression, @Nullable String errorMessageTemplate, @Nullable Object p1) {
+      boolean expression, String errorMessageTemplate, @CheckForNull Object p1) {
     if (!expression) {
       throw new VerifyException(lenientFormat(errorMessageTemplate, p1));
     }
@@ -191,8 +193,7 @@ public static void verify(
    *
    * @since 23.1 (varargs overload since 17.0)
    */
-  public static void verify(
-      boolean expression, @Nullable String errorMessageTemplate, char p1, char p2) {
+  public static void verify(boolean expression, String errorMessageTemplate, char p1, char p2) {
     if (!expression) {
       throw new VerifyException(lenientFormat(errorMessageTemplate, p1, p2));
     }
@@ -206,8 +207,7 @@ public static void verify(
    *
    * @since 23.1 (varargs overload since 17.0)
    */
-  public static void verify(
-      boolean expression, @Nullable String errorMessageTemplate, int p1, char p2) {
+  public static void verify(boolean expression, String errorMessageTemplate, int p1, char p2) {
     if (!expression) {
       throw new VerifyException(lenientFormat(errorMessageTemplate, p1, p2));
     }
@@ -221,8 +221,7 @@ public static void verify(
    *
    * @since 23.1 (varargs overload since 17.0)
    */
-  public static void verify(
-      boolean expression, @Nullable String errorMessageTemplate, long p1, char p2) {
+  public static void verify(boolean expression, String errorMessageTemplate, long p1, char p2) {
     if (!expression) {
       throw new VerifyException(lenientFormat(errorMessageTemplate, p1, p2));
     }
@@ -237,7 +236,7 @@ public static void verify(
    * @since 23.1 (varargs overload since 17.0)
    */
   public static void verify(
-      boolean expression, @Nullable String errorMessageTemplate, @Nullable Object p1, char p2) {
+      boolean expression, String errorMessageTemplate, @CheckForNull Object p1, char p2) {
     if (!expression) {
       throw new VerifyException(lenientFormat(errorMessageTemplate, p1, p2));
     }
@@ -251,8 +250,7 @@ public static void verify(
    *
    * @since 23.1 (varargs overload since 17.0)
    */
-  public static void verify(
-      boolean expression, @Nullable String errorMessageTemplate, char p1, int p2) {
+  public static void verify(boolean expression, String errorMessageTemplate, char p1, int p2) {
     if (!expression) {
       throw new VerifyException(lenientFormat(errorMessageTemplate, p1, p2));
     }
@@ -266,8 +264,7 @@ public static void verify(
    *
    * @since 23.1 (varargs overload since 17.0)
    */
-  public static void verify(
-      boolean expression, @Nullable String errorMessageTemplate, int p1, int p2) {
+  public static void verify(boolean expression, String errorMessageTemplate, int p1, int p2) {
     if (!expression) {
       throw new VerifyException(lenientFormat(errorMessageTemplate, p1, p2));
     }
@@ -281,8 +278,7 @@ public static void verify(
    *
    * @since 23.1 (varargs overload since 17.0)
    */
-  public static void verify(
-      boolean expression, @Nullable String errorMessageTemplate, long p1, int p2) {
+  public static void verify(boolean expression, String errorMessageTemplate, long p1, int p2) {
     if (!expression) {
       throw new VerifyException(lenientFormat(errorMessageTemplate, p1, p2));
     }
@@ -297,7 +293,7 @@ public static void verify(
    * @since 23.1 (varargs overload since 17.0)
    */
   public static void verify(
-      boolean expression, @Nullable String errorMessageTemplate, @Nullable Object p1, int p2) {
+      boolean expression, String errorMessageTemplate, @CheckForNull Object p1, int p2) {
     if (!expression) {
       throw new VerifyException(lenientFormat(errorMessageTemplate, p1, p2));
     }
@@ -311,8 +307,7 @@ public static void verify(
    *
    * @since 23.1 (varargs overload since 17.0)
    */
-  public static void verify(
-      boolean expression, @Nullable String errorMessageTemplate, char p1, long p2) {
+  public static void verify(boolean expression, String errorMessageTemplate, char p1, long p2) {
     if (!expression) {
       throw new VerifyException(lenientFormat(errorMessageTemplate, p1, p2));
     }
@@ -326,8 +321,7 @@ public static void verify(
    *
    * @since 23.1 (varargs overload since 17.0)
    */
-  public static void verify(
-      boolean expression, @Nullable String errorMessageTemplate, int p1, long p2) {
+  public static void verify(boolean expression, String errorMessageTemplate, int p1, long p2) {
     if (!expression) {
       throw new VerifyException(lenientFormat(errorMessageTemplate, p1, p2));
     }
@@ -341,8 +335,7 @@ public static void verify(
    *
    * @since 23.1 (varargs overload since 17.0)
    */
-  public static void verify(
-      boolean expression, @Nullable String errorMessageTemplate, long p1, long p2) {
+  public static void verify(boolean expression, String errorMessageTemplate, long p1, long p2) {
     if (!expression) {
       throw new VerifyException(lenientFormat(errorMessageTemplate, p1, p2));
     }
@@ -357,7 +350,7 @@ public static void verify(
    * @since 23.1 (varargs overload since 17.0)
    */
   public static void verify(
-      boolean expression, @Nullable String errorMessageTemplate, @Nullable Object p1, long p2) {
+      boolean expression, String errorMessageTemplate, @CheckForNull Object p1, long p2) {
     if (!expression) {
       throw new VerifyException(lenientFormat(errorMessageTemplate, p1, p2));
     }
@@ -372,7 +365,7 @@ public static void verify(
    * @since 23.1 (varargs overload since 17.0)
    */
   public static void verify(
-      boolean expression, @Nullable String errorMessageTemplate, char p1, @Nullable Object p2) {
+      boolean expression, String errorMessageTemplate, char p1, @CheckForNull Object p2) {
     if (!expression) {
       throw new VerifyException(lenientFormat(errorMessageTemplate, p1, p2));
     }
@@ -387,7 +380,7 @@ public static void verify(
    * @since 23.1 (varargs overload since 17.0)
    */
   public static void verify(
-      boolean expression, @Nullable String errorMessageTemplate, int p1, @Nullable Object p2) {
+      boolean expression, String errorMessageTemplate, int p1, @CheckForNull Object p2) {
     if (!expression) {
       throw new VerifyException(lenientFormat(errorMessageTemplate, p1, p2));
     }
@@ -402,7 +395,7 @@ public static void verify(
    * @since 23.1 (varargs overload since 17.0)
    */
   public static void verify(
-      boolean expression, @Nullable String errorMessageTemplate, long p1, @Nullable Object p2) {
+      boolean expression, String errorMessageTemplate, long p1, @CheckForNull Object p2) {
     if (!expression) {
       throw new VerifyException(lenientFormat(errorMessageTemplate, p1, p2));
     }
@@ -418,9 +411,9 @@ public static void verify(
    */
   public static void verify(
       boolean expression,
-      @Nullable String errorMessageTemplate,
-      @Nullable Object p1,
-      @Nullable Object p2) {
+      String errorMessageTemplate,
+      @CheckForNull Object p1,
+      @CheckForNull Object p2) {
     if (!expression) {
       throw new VerifyException(lenientFormat(errorMessageTemplate, p1, p2));
     }
@@ -436,10 +429,10 @@ public static void verify(
    */
   public static void verify(
       boolean expression,
-      @Nullable String errorMessageTemplate,
-      @Nullable Object p1,
-      @Nullable Object p2,
-      @Nullable Object p3) {
+      String errorMessageTemplate,
+      @CheckForNull Object p1,
+      @CheckForNull Object p2,
+      @CheckForNull Object p3) {
     if (!expression) {
       throw new VerifyException(lenientFormat(errorMessageTemplate, p1, p2, p3));
     }
@@ -455,16 +448,25 @@ public static void verify(
    */
   public static void verify(
       boolean expression,
-      @Nullable String errorMessageTemplate,
-      @Nullable Object p1,
-      @Nullable Object p2,
-      @Nullable Object p3,
-      @Nullable Object p4) {
+      String errorMessageTemplate,
+      @CheckForNull Object p1,
+      @CheckForNull Object p2,
+      @CheckForNull Object p3,
+      @CheckForNull Object p4) {
     if (!expression) {
       throw new VerifyException(lenientFormat(errorMessageTemplate, p1, p2, p3, p4));
     }
   }
 
+  /*
+   * For a discussion of the signature of verifyNotNull, see the discussion above
+   * Preconditions.checkNotNull.
+   *
+   * (verifyNotNull has many fewer "problem" callers, so we could try to be stricter. On the other
+   * hand, verifyNotNull arguably has more reason to accept nullable arguments in the first
+   * place....)
+   */
+
   /**
    * Ensures that {@code reference} is non-null, throwing a {@code VerifyException} with a default
    * message otherwise.
@@ -474,7 +476,7 @@ public static void verify(
    * @see Preconditions#checkNotNull Preconditions.checkNotNull()
    */
   @CanIgnoreReturnValue
-  public static <T extends @NonNull Object> T verifyNotNull(T reference) {
+  public static <T> T verifyNotNull(@CheckForNull T reference) {
     return verifyNotNull(reference, "expected a non-null reference");
   }
 
@@ -494,11 +496,13 @@ public static void verify(
    * @see Preconditions#checkNotNull Preconditions.checkNotNull()
    */
   @CanIgnoreReturnValue
-  public static <T extends @NonNull Object> T verifyNotNull(
-      T reference,
-      @Nullable String errorMessageTemplate,
-      @Nullable Object @Nullable ... errorMessageArgs) {
-    verify(reference != null, errorMessageTemplate, errorMessageArgs);
+  public static <T> T verifyNotNull(
+      @CheckForNull T reference,
+      String errorMessageTemplate,
+      @CheckForNull @Nullable Object... errorMessageArgs) {
+    if (reference == null) {
+      throw new VerifyException(lenientFormat(errorMessageTemplate, errorMessageArgs));
+    }
     return reference;
   }
 
diff --git a/guava/src/com/google/common/base/VerifyException.java b/guava/src/com/google/common/base/VerifyException.java
index 1b6781b817b2..10b99dee722b 100644
--- a/guava/src/com/google/common/base/VerifyException.java
+++ b/guava/src/com/google/common/base/VerifyException.java
@@ -15,7 +15,7 @@
 package com.google.common.base;
 
 import com.google.common.annotations.GwtCompatible;
-import org.checkerframework.checker.nullness.qual.Nullable;
+import javax.annotation.CheckForNull;
 
 /**
  * Exception thrown upon the failure of a <a
@@ -25,12 +25,13 @@
  * @since 17.0
  */
 @GwtCompatible
+@ElementTypesAreNonnullByDefault
 public class VerifyException extends RuntimeException {
   /** Constructs a {@code VerifyException} with no message. */
   public VerifyException() {}
 
   /** Constructs a {@code VerifyException} with the message {@code message}. */
-  public VerifyException(@Nullable String message) {
+  public VerifyException(@CheckForNull String message) {
     super(message);
   }
 
@@ -40,7 +41,7 @@ public VerifyException(@Nullable String message) {
    *
    * @since 19.0
    */
-  public VerifyException(@Nullable Throwable cause) {
+  public VerifyException(@CheckForNull Throwable cause) {
     super(cause);
   }
 
@@ -50,7 +51,7 @@ public VerifyException(@Nullable Throwable cause) {
    *
    * @since 19.0
    */
-  public VerifyException(@Nullable String message, @Nullable Throwable cause) {
+  public VerifyException(@CheckForNull String message, @CheckForNull Throwable cause) {
     super(message, cause);
   }
 }
diff --git a/guava/src/com/google/common/base/internal/Finalizer.java b/guava/src/com/google/common/base/internal/Finalizer.java
index 766ab78d0232..574d49526506 100644
--- a/guava/src/com/google/common/base/internal/Finalizer.java
+++ b/guava/src/com/google/common/base/internal/Finalizer.java
@@ -23,6 +23,7 @@
 import java.lang.reflect.Method;
 import java.util.logging.Level;
 import java.util.logging.Logger;
+import javax.annotation.CheckForNull;
 import org.checkerframework.checker.nullness.qual.Nullable;
 import org.checkerframework.framework.qual.AnnotatedFor;
 
@@ -45,6 +46,7 @@
  * stop itself.
  */
 @AnnotatedFor({"nullness"})
+// no @ElementTypesAreNonNullByDefault for the reasons discussed above
 public class Finalizer implements Runnable {
 
   private static final Logger logger = Logger.getLogger(Finalizer.class.getName());
@@ -118,10 +120,11 @@ public static void startFinalizer(
   // By preference, we will use the Thread constructor that has an `inheritThreadLocals` parameter.
   // But before Java 9, our only way not to inherit ThreadLocals is to zap them after the thread
   // is created, by accessing a private field.
-  private static final @Nullable Constructor<Thread> bigThreadConstructor =
-      getBigThreadConstructor();
+  @CheckForNull
+  private static final Constructor<Thread> bigThreadConstructor = getBigThreadConstructor();
 
-  private static final @Nullable Field inheritableThreadLocals =
+  @CheckForNull
+  private static final Field inheritableThreadLocals =
       (bigThreadConstructor == null) ? getInheritableThreadLocalsField() : null;
 
   /** Constructs a new finalizer thread. */
@@ -131,8 +134,7 @@ private Finalizer(
       PhantomReference<Object> frqReference) {
     this.queue = queue;
 
-    this.finalizableReferenceClassReference =
-        new WeakReference<Class<?>>(finalizableReferenceClass);
+    this.finalizableReferenceClassReference = new WeakReference<>(finalizableReferenceClass);
 
     // Keep track of the FRQ that started us so we know when to stop.
     this.frqReference = frqReference;
@@ -193,7 +195,8 @@ private boolean cleanUp(Reference<?> reference) {
   }
 
   /** Looks up FinalizableReference.finalizeReferent() method. */
-  private @Nullable Method getFinalizeReferentMethod() {
+  @CheckForNull
+  private Method getFinalizeReferentMethod() {
     Class<?> finalizableReferenceClass = finalizableReferenceClassReference.get();
     if (finalizableReferenceClass == null) {
       /*
@@ -211,7 +214,8 @@ private boolean cleanUp(Reference<?> reference) {
     }
   }
 
-  private static @Nullable Field getInheritableThreadLocalsField() {
+  @CheckForNull
+  private static Field getInheritableThreadLocalsField() {
     try {
       Field inheritableThreadLocals = Thread.class.getDeclaredField("inheritableThreadLocals");
       inheritableThreadLocals.setAccessible(true);
@@ -225,7 +229,8 @@ private boolean cleanUp(Reference<?> reference) {
     }
   }
 
-  private static @Nullable Constructor<Thread> getBigThreadConstructor() {
+  @CheckForNull
+  private static Constructor<Thread> getBigThreadConstructor() {
     try {
       return Thread.class.getConstructor(
           ThreadGroup.class, Runnable.class, String.class, long.class, boolean.class);
diff --git a/guava/src/com/google/common/cache/AbstractCache.java b/guava/src/com/google/common/cache/AbstractCache.java
index d8ef0323a81d..eec5fdc34f56 100644
--- a/guava/src/com/google/common/cache/AbstractCache.java
+++ b/guava/src/com/google/common/cache/AbstractCache.java
@@ -38,6 +38,7 @@
  * @since 10.0
  */
 @GwtCompatible
+@ElementTypesAreNonnullByDefault
 public abstract class AbstractCache<K, V> implements Cache<K, V> {
 
   /** Constructor for use by subclasses. */
@@ -58,8 +59,12 @@ public V get(K key, Callable<? extends V> valueLoader) throws ExecutionException
    *
    * @since 11.0
    */
+  /*
+   * <? extends Object> is mostly the same as <?> to plain Java. But to nullness checkers, they
+   * differ: <? extends Object> means "non-null types," while <?> means "all types."
+   */
   @Override
-  public ImmutableMap<K, V> getAllPresent(Iterable<?> keys) {
+  public ImmutableMap<K, V> getAllPresent(Iterable<? extends Object> keys) {
     Map<K, V> result = Maps.newLinkedHashMap();
     for (Object key : keys) {
       if (!result.containsKey(key)) {
@@ -103,7 +108,8 @@ public void invalidate(Object key) {
 
   /** @since 11.0 */
   @Override
-  public void invalidateAll(Iterable<?> keys) {
+  // For discussion of <? extends Object>, see getAllPresent.
+  public void invalidateAll(Iterable<? extends Object> keys) {
     for (Object key : keys) {
       invalidate(key);
     }
diff --git a/guava/src/com/google/common/cache/AbstractLoadingCache.java b/guava/src/com/google/common/cache/AbstractLoadingCache.java
index 38b97747915e..489597c51843 100644
--- a/guava/src/com/google/common/cache/AbstractLoadingCache.java
+++ b/guava/src/com/google/common/cache/AbstractLoadingCache.java
@@ -38,6 +38,7 @@
  * @since 11.0
  */
 @GwtIncompatible
+@ElementTypesAreNonnullByDefault
 public abstract class AbstractLoadingCache<K, V> extends AbstractCache<K, V>
     implements LoadingCache<K, V> {
 
diff --git a/guava/src/com/google/common/cache/Cache.java b/guava/src/com/google/common/cache/Cache.java
index fd0289be107e..8755595a075d 100644
--- a/guava/src/com/google/common/cache/Cache.java
+++ b/guava/src/com/google/common/cache/Cache.java
@@ -25,7 +25,7 @@
 import java.util.concurrent.Callable;
 import java.util.concurrent.ConcurrentMap;
 import java.util.concurrent.ExecutionException;
-import org.checkerframework.checker.nullness.qual.Nullable;
+import javax.annotation.CheckForNull;
 
 /**
  * A semi-persistent mapping from keys to values. Cache entries are manually added using {@link
@@ -35,11 +35,14 @@
  * <p>Implementations of this interface are expected to be thread-safe, and can be safely accessed
  * by multiple concurrent threads.
  *
+ * @param <K> the type of the cache's keys, which are not permitted to be null
+ * @param <V> the type of the cache's values, which are not permitted to be null
  * @author Charles Fry
  * @since 10.0
  */
 @DoNotMock("Use CacheBuilder.newBuilder().build()")
 @GwtCompatible
+@ElementTypesAreNonnullByDefault
 public interface Cache<K, V> {
 
   /**
@@ -48,7 +51,7 @@ public interface Cache<K, V> {
    *
    * @since 11.0
    */
-  @Nullable
+  @CheckForNull
   V getIfPresent(@CompatibleWith("K") Object key);
 
   /**
@@ -105,7 +108,11 @@ public interface Cache<K, V> {
    *
    * @since 11.0
    */
-  ImmutableMap<K, V> getAllPresent(Iterable<?> keys);
+  /*
+   * <? extends Object> is mostly the same as <?> to plain Java. But to nullness checkers, they
+   * differ: <? extends Object> means "non-null types," while <?> means "all types."
+   */
+  ImmutableMap<K, V> getAllPresent(Iterable<? extends Object> keys);
 
   /**
    * Associates {@code value} with {@code key} in this cache. If the cache previously contained a
@@ -136,7 +143,8 @@ public interface Cache<K, V> {
    *
    * @since 11.0
    */
-  void invalidateAll(Iterable<?> keys);
+  // For discussion of <? extends Object>, see getAllPresent.
+  void invalidateAll(Iterable<? extends Object> keys);
 
   /** Discards all entries in the cache. */
   void invalidateAll();
diff --git a/guava/src/com/google/common/cache/CacheBuilder.java b/guava/src/com/google/common/cache/CacheBuilder.java
index d0189660554e..668769b6ecfa 100644
--- a/guava/src/com/google/common/cache/CacheBuilder.java
+++ b/guava/src/com/google/common/cache/CacheBuilder.java
@@ -41,12 +41,54 @@
 import org.checkerframework.checker.nullness.qual.Nullable;
 
 /**
- * A builder of {@link LoadingCache} and {@link Cache} instances having any combination of the
- * following features:
+ * A builder of {@link LoadingCache} and {@link Cache} instances.
+ *
+ * <h2>Prefer <a href="https://github.com/ben-manes/caffeine/wiki">Caffeine</a> over Guava's caching
+ * API</h2>
+ *
+ * <p>The successor to Guava's caching API is <a
+ * href="https://github.com/ben-manes/caffeine/wiki">Caffeine</a>. Its API is designed to make it a
+ * nearly drop-in replacement -- though it requires Java 8 APIs, is not available for Android or
+ * GWT/j2cl, and may have <a href="https://github.com/ben-manes/caffeine/wiki/Guava">different
+ * (usually better) behavior</a> when multiple threads attempt concurrent mutations. Its equivalent
+ * to {@code CacheBuilder} is its <a
+ * href="https://www.javadoc.io/doc/com.github.ben-manes.caffeine/caffeine/latest/com.github.benmanes.caffeine/com/github/benmanes/caffeine/cache/Caffeine.html">{@code
+ * Caffeine}</a> class. Caffeine offers better performance, more features (including asynchronous
+ * loading), and fewer <a
+ * href="https://github.com/google/guava/issues?q=is%3Aopen+is%3Aissue+label%3Apackage%3Dcache+label%3Atype%3Ddefect">bugs</a>.
+ *
+ * <p>Caffeine defines its own interfaces (<a
+ * href="https://www.javadoc.io/doc/com.github.ben-manes.caffeine/caffeine/latest/com.github.benmanes.caffeine/com/github/benmanes/caffeine/cache/Cache.html">{@code
+ * Cache}</a>, <a
+ * href="https://www.javadoc.io/doc/com.github.ben-manes.caffeine/caffeine/latest/com.github.benmanes.caffeine/com/github/benmanes/caffeine/cache/LoadingCache.html">{@code
+ * LoadingCache}</a>, <a
+ * href="https://www.javadoc.io/doc/com.github.ben-manes.caffeine/caffeine/latest/com.github.benmanes.caffeine/com/github/benmanes/caffeine/cache/CacheLoader.html">{@code
+ * CacheLoader}</a>, etc.), so you can use Caffeine without needing to use any Guava types.
+ * Caffeine's types are better than Guava's, especially for <a
+ * href="https://www.javadoc.io/doc/com.github.ben-manes.caffeine/caffeine/latest/com.github.benmanes.caffeine/com/github/benmanes/caffeine/cache/AsyncLoadingCache.html">their
+ * deep support for asynchronous operations</a>. But if you want to migrate to Caffeine with minimal
+ * code changes, you can use <a
+ * href="https://www.javadoc.io/doc/com.github.ben-manes.caffeine/guava/latest/com.github.benmanes.caffeine.guava/com/github/benmanes/caffeine/guava/CaffeinatedGuava.html">its
+ * {@code CaffeinatedGuava} adapter class</a>, which lets you build a Guava {@code Cache} or a Guava
+ * {@code LoadingCache} backed by a Guava {@code CacheLoader}.
+ *
+ * <p>Caffeine's API for asynchronous operations uses {@code CompletableFuture}: <a
+ * href="https://www.javadoc.io/doc/com.github.ben-manes.caffeine/caffeine/latest/com.github.benmanes.caffeine/com/github/benmanes/caffeine/cache/AsyncLoadingCache.html#get(K)">{@code
+ * AsyncLoadingCache.get}</a> returns a {@code CompletableFuture}, and implementations of <a
+ * href="https://www.javadoc.io/doc/com.github.ben-manes.caffeine/caffeine/latest/com.github.benmanes.caffeine/com/github/benmanes/caffeine/cache/AsyncCacheLoader.html#asyncLoad(K,java.util.concurrent.Executor)">{@code
+ * AsyncCacheLoader.asyncLoad}</a> must return a {@code CompletableFuture}. Users of Guava's {@link
+ * com.google.common.util.concurrent.ListenableFuture} can adapt between the two {@code Future}
+ * types by using <a href="https://github.com/lukas-krecan/future-converter#java8-guava">{@code
+ * net.javacrumbs.futureconverter.java8guava.FutureConverter}</a>.
+ *
+ * <h2>More on {@code CacheBuilder}</h2>
+ *
+ * {@code CacheBuilder} builds caches with any combination of the following features:
  *
  * <ul>
  *   <li>automatic loading of entries into the cache
- *   <li>least-recently-used eviction when a maximum size is exceeded
+ *   <li>least-recently-used eviction when a maximum size is exceeded (note that the cache is
+ *       divided into segments, each of which does LRU internally)
  *   <li>time-based expiration of entries, measured since last access or last write
  *   <li>keys automatically wrapped in {@code WeakReference}
  *   <li>values automatically wrapped in {@code WeakReference} or {@code SoftReference}
@@ -141,15 +183,16 @@
  *
  * @param <K> the most general key type this builder will be able to create caches for. This is
  *     normally {@code Object} unless it is constrained by using a method like {@code
- *     #removalListener}
+ *     #removalListener}. Cache keys may not be null.
  * @param <V> the most general value type this builder will be able to create caches for. This is
  *     normally {@code Object} unless it is constrained by using a method like {@code
- *     #removalListener}
+ *     #removalListener}. Cache values may not be null.
  * @author Charles Fry
  * @author Kevin Bourrillion
  * @since 10.0
  */
 @GwtCompatible(emulated = true)
+@ElementTypesAreNonnullByDefault
 public final class CacheBuilder<K, V> {
   private static final int DEFAULT_INITIAL_CAPACITY = 16;
   private static final int DEFAULT_CONCURRENCY_LEVEL = 4;
@@ -648,7 +691,7 @@ Strength getValueStrength() {
    *     removed
    * @return this {@code CacheBuilder} instance (for chaining)
    * @throws IllegalArgumentException if {@code duration} is negative
-   * @throws IllegalStateException if the time to live or time to idle was already set
+   * @throws IllegalStateException if {@link #expireAfterWrite} was already set
    * @throws ArithmeticException for durations greater than +/- approximately 292 years
    * @since 25.0
    */
@@ -679,7 +722,7 @@ public CacheBuilder<K, V> expireAfterWrite(java.time.Duration duration) {
    * @param unit the unit that {@code duration} is expressed in
    * @return this {@code CacheBuilder} instance (for chaining)
    * @throws IllegalArgumentException if {@code duration} is negative
-   * @throws IllegalStateException if the time to live or time to idle was already set
+   * @throws IllegalStateException if {@link #expireAfterWrite} was already set
    */
   @SuppressWarnings("GoodTime") // should accept a java.time.Duration
   public CacheBuilder<K, V> expireAfterWrite(long duration, TimeUnit unit) {
@@ -718,7 +761,7 @@ long getExpireAfterWriteNanos() {
    *     automatically removed
    * @return this {@code CacheBuilder} instance (for chaining)
    * @throws IllegalArgumentException if {@code duration} is negative
-   * @throws IllegalStateException if the time to idle or time to live was already set
+   * @throws IllegalStateException if {@link #expireAfterAccess} was already set
    * @throws ArithmeticException for durations greater than +/- approximately 292 years
    * @since 25.0
    */
@@ -754,7 +797,7 @@ public CacheBuilder<K, V> expireAfterAccess(java.time.Duration duration) {
    * @param unit the unit that {@code duration} is expressed in
    * @return this {@code CacheBuilder} instance (for chaining)
    * @throws IllegalArgumentException if {@code duration} is negative
-   * @throws IllegalStateException if the time to idle or time to live was already set
+   * @throws IllegalStateException if {@link #expireAfterAccess} was already set
    */
   @SuppressWarnings("GoodTime") // should accept a java.time.Duration
   public CacheBuilder<K, V> expireAfterAccess(long duration, TimeUnit unit) {
@@ -786,9 +829,10 @@ long getExpireAfterAccessNanos() {
    * operations.
    *
    * <p>Currently automatic refreshes are performed when the first stale request for an entry
-   * occurs. The request triggering refresh will make a blocking call to {@link CacheLoader#reload}
-   * and immediately return the new value if the returned future is complete, and the old value
-   * otherwise.
+   * occurs. The request triggering refresh will make a synchronous call to {@link
+   * CacheLoader#reload}
+   * to obtain a future of the new value. If the returned future is already complete, it is returned
+   * immediately. Otherwise, the old value is returned.
    *
    * <p><b>Note:</b> <i>all exceptions thrown during refresh will be logged and then swallowed</i>.
    *
@@ -796,7 +840,7 @@ long getExpireAfterAccessNanos() {
    *     stale, and thus eligible for refresh
    * @return this {@code CacheBuilder} instance (for chaining)
    * @throws IllegalArgumentException if {@code duration} is negative
-   * @throws IllegalStateException if the refresh interval was already set
+   * @throws IllegalStateException if {@link #refreshAfterWrite} was already set
    * @throws ArithmeticException for durations greater than +/- approximately 292 years
    * @since 25.0
    */
@@ -819,7 +863,8 @@ public CacheBuilder<K, V> refreshAfterWrite(java.time.Duration duration) {
    * operations.
    *
    * <p>Currently automatic refreshes are performed when the first stale request for an entry
-   * occurs. The request triggering refresh will make a blocking call to {@link CacheLoader#reload}
+   * occurs. The request triggering refresh will make a synchronous call to {@link
+   * CacheLoader#reload}
    * and immediately return the new value if the returned future is complete, and the old value
    * otherwise.
    *
@@ -833,7 +878,7 @@ public CacheBuilder<K, V> refreshAfterWrite(java.time.Duration duration) {
    * @param unit the unit that {@code duration} is expressed in
    * @return this {@code CacheBuilder} instance (for chaining)
    * @throws IllegalArgumentException if {@code duration} is negative
-   * @throws IllegalStateException if the refresh interval was already set
+   * @throws IllegalStateException if {@link #refreshAfterWrite} was already set
    * @since 11.0
    */
   @GwtIncompatible // To be supported (synchronously).
diff --git a/guava/src/com/google/common/cache/CacheBuilderSpec.java b/guava/src/com/google/common/cache/CacheBuilderSpec.java
index cba67213f154..3e5c1786c1c0 100644
--- a/guava/src/com/google/common/cache/CacheBuilderSpec.java
+++ b/guava/src/com/google/common/cache/CacheBuilderSpec.java
@@ -15,6 +15,7 @@
 package com.google.common.cache;
 
 import static com.google.common.base.Preconditions.checkArgument;
+import static com.google.common.base.Strings.isNullOrEmpty;
 
 import com.google.common.annotations.GwtIncompatible;
 import com.google.common.annotations.VisibleForTesting;
@@ -27,6 +28,8 @@
 import java.util.List;
 import java.util.Locale;
 import java.util.concurrent.TimeUnit;
+import javax.annotation.CheckForNull;
+import org.checkerframework.checker.formatter.qual.FormatMethod;
 import org.checkerframework.checker.nullness.qual.Nullable;
 
 /**
@@ -78,10 +81,11 @@
  */
 @SuppressWarnings("GoodTime") // lots of violations (nanosecond math)
 @GwtIncompatible
+@ElementTypesAreNonnullByDefault
 public final class CacheBuilderSpec {
   /** Parses a single value. */
   private interface ValueParser {
-    void parse(CacheBuilderSpec spec, String key, @Nullable String value);
+    void parse(CacheBuilderSpec spec, String key, @CheckForNull String value);
   }
 
   /** Splits each key-value pair. */
@@ -105,21 +109,21 @@ private interface ValueParser {
           .put("expireAfterWrite", new WriteDurationParser())
           .put("refreshAfterWrite", new RefreshDurationParser())
           .put("refreshInterval", new RefreshDurationParser())
-          .build();
-
-  @VisibleForTesting @Nullable Integer initialCapacity;
-  @VisibleForTesting @Nullable Long maximumSize;
-  @VisibleForTesting @Nullable Long maximumWeight;
-  @VisibleForTesting @Nullable Integer concurrencyLevel;
-  @VisibleForTesting @Nullable Strength keyStrength;
-  @VisibleForTesting @Nullable Strength valueStrength;
-  @VisibleForTesting @Nullable Boolean recordStats;
+          .buildOrThrow();
+
+  @VisibleForTesting @CheckForNull Integer initialCapacity;
+  @VisibleForTesting @CheckForNull Long maximumSize;
+  @VisibleForTesting @CheckForNull Long maximumWeight;
+  @VisibleForTesting @CheckForNull Integer concurrencyLevel;
+  @VisibleForTesting @CheckForNull Strength keyStrength;
+  @VisibleForTesting @CheckForNull Strength valueStrength;
+  @VisibleForTesting @CheckForNull Boolean recordStats;
   @VisibleForTesting long writeExpirationDuration;
-  @VisibleForTesting @Nullable TimeUnit writeExpirationTimeUnit;
+  @VisibleForTesting @CheckForNull TimeUnit writeExpirationTimeUnit;
   @VisibleForTesting long accessExpirationDuration;
-  @VisibleForTesting @Nullable TimeUnit accessExpirationTimeUnit;
+  @VisibleForTesting @CheckForNull TimeUnit accessExpirationTimeUnit;
   @VisibleForTesting long refreshDuration;
-  @VisibleForTesting @Nullable TimeUnit refreshTimeUnit;
+  @VisibleForTesting @CheckForNull TimeUnit refreshTimeUnit;
   /** Specification; used for toParseableString(). */
   private final String specification;
 
@@ -248,7 +252,7 @@ public int hashCode() {
   }
 
   @Override
-  public boolean equals(@Nullable Object obj) {
+  public boolean equals(@CheckForNull Object obj) {
     if (this == obj) {
       return true;
     }
@@ -278,7 +282,8 @@ public boolean equals(@Nullable Object obj) {
    * Converts an expiration duration/unit pair into a single Long for hashing and equality. Uses
    * nanos to match CacheBuilder implementation.
    */
-  private static @Nullable Long durationInNanos(long duration, @Nullable TimeUnit unit) {
+  @CheckForNull
+  private static Long durationInNanos(long duration, @CheckForNull TimeUnit unit) {
     return (unit == null) ? null : unit.toNanos(duration);
   }
 
@@ -287,8 +292,10 @@ abstract static class IntegerParser implements ValueParser {
     protected abstract void parseInteger(CacheBuilderSpec spec, int value);
 
     @Override
-    public void parse(CacheBuilderSpec spec, String key, String value) {
-      checkArgument(value != null && !value.isEmpty(), "value of key %s omitted", key);
+    public void parse(CacheBuilderSpec spec, String key, @Nullable String value) {
+      if (isNullOrEmpty(value)) {
+        throw new IllegalArgumentException("value of key " + key + " omitted");
+      }
       try {
         parseInteger(spec, Integer.parseInt(value));
       } catch (NumberFormatException e) {
@@ -303,8 +310,10 @@ abstract static class LongParser implements ValueParser {
     protected abstract void parseLong(CacheBuilderSpec spec, long value);
 
     @Override
-    public void parse(CacheBuilderSpec spec, String key, String value) {
-      checkArgument(value != null && !value.isEmpty(), "value of key %s omitted", key);
+    public void parse(CacheBuilderSpec spec, String key, @Nullable String value) {
+      if (isNullOrEmpty(value)) {
+        throw new IllegalArgumentException("value of key " + key + " omitted");
+      }
       try {
         parseLong(spec, Long.parseLong(value));
       } catch (NumberFormatException e) {
@@ -369,7 +378,7 @@ public KeyStrengthParser(Strength strength) {
     }
 
     @Override
-    public void parse(CacheBuilderSpec spec, String key, @Nullable String value) {
+    public void parse(CacheBuilderSpec spec, String key, @CheckForNull String value) {
       checkArgument(value == null, "key %s does not take values", key);
       checkArgument(spec.keyStrength == null, "%s was already set to %s", key, spec.keyStrength);
       spec.keyStrength = strength;
@@ -385,7 +394,7 @@ public ValueStrengthParser(Strength strength) {
     }
 
     @Override
-    public void parse(CacheBuilderSpec spec, String key, @Nullable String value) {
+    public void parse(CacheBuilderSpec spec, String key, @CheckForNull String value) {
       checkArgument(value == null, "key %s does not take values", key);
       checkArgument(
           spec.valueStrength == null, "%s was already set to %s", key, spec.valueStrength);
@@ -398,7 +407,7 @@ public void parse(CacheBuilderSpec spec, String key, @Nullable String value) {
   static class RecordStatsParser implements ValueParser {
 
     @Override
-    public void parse(CacheBuilderSpec spec, String key, @Nullable String value) {
+    public void parse(CacheBuilderSpec spec, String key, @CheckForNull String value) {
       checkArgument(value == null, "recordStats does not take values");
       checkArgument(spec.recordStats == null, "recordStats already set");
       spec.recordStats = true;
@@ -410,8 +419,10 @@ abstract static class DurationParser implements ValueParser {
     protected abstract void parseDuration(CacheBuilderSpec spec, long duration, TimeUnit unit);
 
     @Override
-    public void parse(CacheBuilderSpec spec, String key, String value) {
-      checkArgument(value != null && !value.isEmpty(), "value of key %s omitted", key);
+    public void parse(CacheBuilderSpec spec, String key, @CheckForNull String value) {
+      if (isNullOrEmpty(value)) {
+        throw new IllegalArgumentException("value of key " + key + " omitted");
+      }
       try {
         char lastChar = value.charAt(value.length() - 1);
         TimeUnit timeUnit;
@@ -430,8 +441,7 @@ public void parse(CacheBuilderSpec spec, String key, String value) {
             break;
           default:
             throw new IllegalArgumentException(
-                format(
-                    "key %s invalid format.  was %s, must end with one of [dDhHmMsS]", key, value));
+                format("key %s invalid unit: was %s, must end with one of [dhms]", key, value));
         }
 
         long duration = Long.parseLong(value.substring(0, value.length() - 1));
@@ -473,6 +483,7 @@ protected void parseDuration(CacheBuilderSpec spec, long duration, TimeUnit unit
     }
   }
 
+  @FormatMethod
   private static String format(String format, Object... args) {
     return String.format(Locale.ROOT, format, args);
   }
diff --git a/guava/src/com/google/common/cache/CacheLoader.java b/guava/src/com/google/common/cache/CacheLoader.java
index 2a3ff1b908ac..7a5e017d03d4 100644
--- a/guava/src/com/google/common/cache/CacheLoader.java
+++ b/guava/src/com/google/common/cache/CacheLoader.java
@@ -57,6 +57,7 @@
  * @since 10.0
  */
 @GwtCompatible(emulated = true)
+@ElementTypesAreNonnullByDefault
 public abstract class CacheLoader<K, V> {
   /** Constructor for use by subclasses. */
   protected CacheLoader() {}
diff --git a/guava/src/com/google/common/cache/CacheStats.java b/guava/src/com/google/common/cache/CacheStats.java
index 777d53fa04e3..8307e942a818 100644
--- a/guava/src/com/google/common/cache/CacheStats.java
+++ b/guava/src/com/google/common/cache/CacheStats.java
@@ -22,7 +22,7 @@
 import com.google.common.base.MoreObjects;
 import com.google.common.base.Objects;
 import java.util.concurrent.Callable;
-import org.checkerframework.checker.nullness.qual.Nullable;
+import javax.annotation.CheckForNull;
 
 /**
  * Statistics about the performance of a {@link Cache}. Instances of this class are immutable.
@@ -57,6 +57,7 @@
  * @since 10.0
  */
 @GwtCompatible
+@ElementTypesAreNonnullByDefault
 public final class CacheStats {
   private final long hitCount;
   private final long missCount;
@@ -276,7 +277,7 @@ public int hashCode() {
   }
 
   @Override
-  public boolean equals(@Nullable Object object) {
+  public boolean equals(@CheckForNull Object object) {
     if (object instanceof CacheStats) {
       CacheStats other = (CacheStats) object;
       return hitCount == other.hitCount
diff --git a/guava/src/com/google/common/cache/ElementTypesAreNonnullByDefault.java b/guava/src/com/google/common/cache/ElementTypesAreNonnullByDefault.java
new file mode 100644
index 000000000000..bcf0fcef1c48
--- /dev/null
+++ b/guava/src/com/google/common/cache/ElementTypesAreNonnullByDefault.java
@@ -0,0 +1,41 @@
+/*
+ * Copyright (C) 2021 The Guava Authors
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package com.google.common.cache;
+
+import static java.lang.annotation.ElementType.FIELD;
+import static java.lang.annotation.ElementType.METHOD;
+import static java.lang.annotation.ElementType.PARAMETER;
+import static java.lang.annotation.ElementType.TYPE;
+import static java.lang.annotation.RetentionPolicy.RUNTIME;
+
+import com.google.common.annotations.GwtCompatible;
+import java.lang.annotation.Retention;
+import java.lang.annotation.Target;
+import javax.annotation.Nonnull;
+import javax.annotation.meta.TypeQualifierDefault;
+
+/**
+ * Marks all "top-level" types as non-null in a way that is recognized by Kotlin. Note that this
+ * unfortunately includes type-variable usages, so we also provide {@link ParametricNullness} to
+ * "undo" it as best we can.
+ */
+@GwtCompatible
+@Retention(RUNTIME)
+@Target(TYPE)
+@TypeQualifierDefault({FIELD, METHOD, PARAMETER})
+@Nonnull
+@interface ElementTypesAreNonnullByDefault {}
diff --git a/guava/src/com/google/common/cache/ForwardingCache.java b/guava/src/com/google/common/cache/ForwardingCache.java
index 81dbf7acefa4..f118977b09a3 100644
--- a/guava/src/com/google/common/cache/ForwardingCache.java
+++ b/guava/src/com/google/common/cache/ForwardingCache.java
@@ -22,7 +22,7 @@
 import java.util.concurrent.Callable;
 import java.util.concurrent.ConcurrentMap;
 import java.util.concurrent.ExecutionException;
-import org.checkerframework.checker.nullness.qual.Nullable;
+import javax.annotation.CheckForNull;
 
 /**
  * A cache which forwards all its method calls to another cache. Subclasses should override one or
@@ -33,6 +33,7 @@
  * @since 10.0
  */
 @GwtIncompatible
+@ElementTypesAreNonnullByDefault
 public abstract class ForwardingCache<K, V> extends ForwardingObject implements Cache<K, V> {
 
   /** Constructor for use by subclasses. */
@@ -43,7 +44,8 @@ protected ForwardingCache() {}
 
   /** @since 11.0 */
   @Override
-  public @Nullable V getIfPresent(Object key) {
+  @CheckForNull
+  public V getIfPresent(Object key) {
     return delegate().getIfPresent(key);
   }
 
@@ -55,7 +57,11 @@ public V get(K key, Callable<? extends V> valueLoader) throws ExecutionException
 
   /** @since 11.0 */
   @Override
-  public ImmutableMap<K, V> getAllPresent(Iterable<?> keys) {
+  /*
+   * <? extends Object> is mostly the same as <?> to plain Java. But to nullness checkers, they
+   * differ: <? extends Object> means "non-null types," while <?> means "all types."
+   */
+  public ImmutableMap<K, V> getAllPresent(Iterable<? extends Object> keys) {
     return delegate().getAllPresent(keys);
   }
 
@@ -78,7 +84,8 @@ public void invalidate(Object key) {
 
   /** @since 11.0 */
   @Override
-  public void invalidateAll(Iterable<?> keys) {
+  // For discussion of <? extends Object>, see getAllPresent.
+  public void invalidateAll(Iterable<? extends Object> keys) {
     delegate().invalidateAll(keys);
   }
 
diff --git a/guava/src/com/google/common/cache/ForwardingLoadingCache.java b/guava/src/com/google/common/cache/ForwardingLoadingCache.java
index ba88ded9bbc1..ecd44ca8d8a9 100644
--- a/guava/src/com/google/common/cache/ForwardingLoadingCache.java
+++ b/guava/src/com/google/common/cache/ForwardingLoadingCache.java
@@ -31,6 +31,7 @@
  * @since 11.0
  */
 @GwtIncompatible
+@ElementTypesAreNonnullByDefault
 public abstract class ForwardingLoadingCache<K, V> extends ForwardingCache<K, V>
     implements LoadingCache<K, V> {
 
diff --git a/guava/src/com/google/common/cache/LoadingCache.java b/guava/src/com/google/common/cache/LoadingCache.java
index 9e812c3ac9bf..e338ac4c3733 100644
--- a/guava/src/com/google/common/cache/LoadingCache.java
+++ b/guava/src/com/google/common/cache/LoadingCache.java
@@ -33,10 +33,13 @@
  * <p>When evaluated as a {@link Function}, a cache yields the same result as invoking {@link
  * #getUnchecked}.
  *
+ * @param <K> the type of the cache's keys, which are not permitted to be null
+ * @param <V> the type of the cache's values, which are not permitted to be null
  * @author Charles Fry
  * @since 11.0
  */
 @GwtCompatible
+@ElementTypesAreNonnullByDefault
 public interface LoadingCache<K, V> extends Cache<K, V>, Function<K, V> {
 
   /**
diff --git a/guava/src/com/google/common/cache/LocalCache.java b/guava/src/com/google/common/cache/LocalCache.java
index cc0dd8ee0168..56e32c8f97d6 100644
--- a/guava/src/com/google/common/cache/LocalCache.java
+++ b/guava/src/com/google/common/cache/LocalCache.java
@@ -21,6 +21,7 @@
 import static com.google.common.util.concurrent.Futures.transform;
 import static com.google.common.util.concurrent.MoreExecutors.directExecutor;
 import static com.google.common.util.concurrent.Uninterruptibles.getUninterruptibly;
+import static java.util.Collections.unmodifiableSet;
 import static java.util.concurrent.TimeUnit.NANOSECONDS;
 
 import com.google.common.annotations.GwtCompatible;
@@ -35,7 +36,6 @@
 import com.google.common.cache.CacheBuilder.OneWeigher;
 import com.google.common.cache.CacheLoader.InvalidCacheLoadException;
 import com.google.common.cache.CacheLoader.UnsupportedLoadingOperationException;
-import com.google.common.cache.LocalCache.AbstractCacheSet;
 import com.google.common.collect.AbstractSequentialIterator;
 import com.google.common.collect.ImmutableMap;
 import com.google.common.collect.ImmutableSet;
@@ -97,8 +97,12 @@
  * @author Bob Lee ({@code com.google.common.collect.MapMaker})
  * @author Doug Lea ({@code ConcurrentHashMap})
  */
-@SuppressWarnings("GoodTime") // lots of violations (nanosecond math)
+@SuppressWarnings({
+  "GoodTime", // lots of violations (nanosecond math)
+  "nullness", // too much trouble for the payoff
+})
 @GwtCompatible(emulated = true)
+// TODO(cpovirk): Annotate for nullness.
 class LocalCache<K, V> extends AbstractMap<K, V> implements ConcurrentMap<K, V> {
 
   /*
@@ -2185,7 +2189,7 @@ V waitForLoadingValue(ReferenceEntry<K, V> e, K key, ValueReference<K, V> valueR
       }
     }
 
-    V compute(K key, int hash, BiFunction<? super K, ? super V, ? extends V> function) {
+    V compute(K key, int hash, BiFunction<? super K, ? super @Nullable V, ? extends V> function) {
       ReferenceEntry<K, V> e;
       ValueReference<K, V> valueReference = null;
       ComputingValueReference<K, V> computingValueReference = null;
@@ -3554,7 +3558,7 @@ public V apply(V newValue) {
       }
     }
 
-    public V compute(K key, BiFunction<? super K, ? super V, ? extends V> function) {
+    public V compute(K key, BiFunction<? super K, ? super @Nullable V, ? extends V> function) {
       stopwatch.start();
       V previousValue;
       try {
@@ -3989,7 +3993,7 @@ ImmutableMap<K, V> getAllPresent(Iterable<?> keys) {
     int hits = 0;
     int misses = 0;
 
-    Map<K, V> result = Maps.newLinkedHashMap();
+    ImmutableMap.Builder<K, V> result = ImmutableMap.builder();
     for (Object key : keys) {
       V value = get(key);
       if (value == null) {
@@ -4004,7 +4008,7 @@ ImmutableMap<K, V> getAllPresent(Iterable<?> keys) {
     }
     globalStatsCounter.recordHits(hits);
     globalStatsCounter.recordMisses(misses);
-    return ImmutableMap.copyOf(result);
+    return result.buildKeepingLast();
   }
 
   ImmutableMap<K, V> getAll(Iterable<? extends K> keys) throws ExecutionException {
@@ -4029,7 +4033,7 @@ ImmutableMap<K, V> getAll(Iterable<? extends K> keys) throws ExecutionException
     try {
       if (!keysToLoad.isEmpty()) {
         try {
-          Map<K, V> newEntries = loadAll(keysToLoad, defaultLoader);
+          Map<K, V> newEntries = loadAll(unmodifiableSet(keysToLoad), defaultLoader);
           for (K key : keysToLoad) {
             V value = newEntries.get(key);
             if (value == null) {
@@ -4065,7 +4069,7 @@ Map<K, V> loadAll(Set<? extends K> keys, CacheLoader<? super K, V> loader)
     Map<K, V> result;
     boolean success = false;
     try {
-      @SuppressWarnings("unchecked") // safe since all keys extend K
+      @SuppressWarnings({"unchecked", "argument"}) // safe since all keys extend K
       Map<K, V> map = (Map<K, V>) loader.loadAll(keys);
       result = map;
       success = true;
@@ -4201,7 +4205,7 @@ public V putIfAbsent(K key, V value) {
   }
 
   @Override
-  public V compute(K key, BiFunction<? super K, ? super V, ? extends V> function) {
+  public V compute(K key, BiFunction<? super K, ? super @Nullable V, ? extends V> function) {
     checkNotNull(key);
     checkNotNull(function);
     int hash = hash(key);
diff --git a/guava/src/com/google/common/cache/LongAddable.java b/guava/src/com/google/common/cache/LongAddable.java
index eaa641467738..9851052d6817 100644
--- a/guava/src/com/google/common/cache/LongAddable.java
+++ b/guava/src/com/google/common/cache/LongAddable.java
@@ -22,6 +22,7 @@
  * @author Louis Wasserman
  */
 @GwtCompatible
+@ElementTypesAreNonnullByDefault
 interface LongAddable {
   void increment();
 
diff --git a/guava/src/com/google/common/cache/LongAddables.java b/guava/src/com/google/common/cache/LongAddables.java
index 203d2ef731a8..249c6e149d95 100644
--- a/guava/src/com/google/common/cache/LongAddables.java
+++ b/guava/src/com/google/common/cache/LongAddables.java
@@ -24,13 +24,15 @@
  * @author Louis Wasserman
  */
 @GwtCompatible(emulated = true)
+@ElementTypesAreNonnullByDefault
 final class LongAddables {
   private static final Supplier<LongAddable> SUPPLIER;
 
   static {
     Supplier<LongAddable> supplier;
     try {
-      new LongAdder(); // trigger static initialization of the LongAdder class, which may fail
+      // trigger static initialization of the LongAdder class, which may fail
+      LongAdder unused = new LongAdder();
       supplier =
           new Supplier<LongAddable>() {
             @Override
diff --git a/guava/src/com/google/common/cache/LongAdder.java b/guava/src/com/google/common/cache/LongAdder.java
index 9b09b63749e8..1ca392e81bfe 100644
--- a/guava/src/com/google/common/cache/LongAdder.java
+++ b/guava/src/com/google/common/cache/LongAdder.java
@@ -42,6 +42,7 @@
  * @author Doug Lea
  */
 @GwtCompatible(emulated = true)
+@ElementTypesAreNonnullByDefault
 final class LongAdder extends Striped64 implements Serializable, LongAddable {
   private static final long serialVersionUID = 7249069246863182397L;
 
diff --git a/guava/src/com/google/common/cache/ParametricNullness.java b/guava/src/com/google/common/cache/ParametricNullness.java
new file mode 100644
index 000000000000..64682de55333
--- /dev/null
+++ b/guava/src/com/google/common/cache/ParametricNullness.java
@@ -0,0 +1,52 @@
+/*
+ * Copyright (C) 2021 The Guava Authors
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package com.google.common.cache;
+
+import static java.lang.annotation.ElementType.FIELD;
+import static java.lang.annotation.ElementType.METHOD;
+import static java.lang.annotation.ElementType.PARAMETER;
+import static java.lang.annotation.RetentionPolicy.RUNTIME;
+
+import com.google.common.annotations.GwtCompatible;
+import java.lang.annotation.Retention;
+import java.lang.annotation.Target;
+
+/**
+ * Marks a "top-level" type-variable usage as the closest we can get to "non-nullable when
+ * non-nullable; nullable when nullable" (like the Android <a
+ * href="https://android.googlesource.com/platform/libcore/+/master/luni/src/main/java/libcore/util/NullFromTypeParam.java">{@code
+ * NullFromTypeParam}</a>).
+ *
+ * <p>Consumers of this annotation include:
+ *
+ * <ul>
+ *   <li>Kotlin, for which it makes the type-variable usage (a) a Kotlin platform type when the type
+ *       argument is non-nullable and (b) nullable when the type argument is nullable. We use this
+ *       to "undo" {@link ElementTypesAreNonnullByDefault}.
+ *   <li><a href="https://developers.google.com/j2objc">J2ObjC</a>
+ *   <li>{@code NullPointerTester}, at least in the Android backport (where the type-use annotations
+ *       {@code NullPointerTester} would need are not available) and in case of <a
+ *       href="https://bugs.openjdk.java.net/browse/JDK-8202469">JDK-8202469</a>
+ * </ul>
+ *
+ */
+@GwtCompatible
+@Retention(RUNTIME)
+@Target({FIELD, METHOD, PARAMETER})
+@javax.annotation.meta.TypeQualifierNickname
+@javax.annotation.Nonnull(when = javax.annotation.meta.When.UNKNOWN)
+@interface ParametricNullness {}
diff --git a/guava/src/com/google/common/cache/ReferenceEntry.java b/guava/src/com/google/common/cache/ReferenceEntry.java
index 63bf2fe9f29b..8ff2e6c9b4ff 100644
--- a/guava/src/com/google/common/cache/ReferenceEntry.java
+++ b/guava/src/com/google/common/cache/ReferenceEntry.java
@@ -16,7 +16,7 @@
 
 import com.google.common.annotations.GwtIncompatible;
 import com.google.common.cache.LocalCache.ValueReference;
-import org.checkerframework.checker.nullness.qual.Nullable;
+import javax.annotation.CheckForNull;
 
 /**
  * An entry in a reference map.
@@ -39,22 +39,24 @@
  * </ul>
  */
 @GwtIncompatible
+@ElementTypesAreNonnullByDefault
 interface ReferenceEntry<K, V> {
   /** Returns the value reference from this entry. */
+  @CheckForNull
   ValueReference<K, V> getValueReference();
 
   /** Sets the value reference for this entry. */
   void setValueReference(ValueReference<K, V> valueReference);
 
   /** Returns the next entry in the chain. */
-  @Nullable
+  @CheckForNull
   ReferenceEntry<K, V> getNext();
 
   /** Returns the entry's hash. */
   int getHash();
 
   /** Returns the key for this entry. */
-  @Nullable
+  @CheckForNull
   K getKey();
 
   /*
diff --git a/guava/src/com/google/common/cache/RemovalCause.java b/guava/src/com/google/common/cache/RemovalCause.java
index 8ecc1d662736..2e68e68b582c 100644
--- a/guava/src/com/google/common/cache/RemovalCause.java
+++ b/guava/src/com/google/common/cache/RemovalCause.java
@@ -26,6 +26,7 @@
  * @since 10.0
  */
 @GwtCompatible
+@ElementTypesAreNonnullByDefault
 public enum RemovalCause {
   /**
    * The entry was manually removed by the user. This can result from the user invoking {@link
diff --git a/guava/src/com/google/common/cache/RemovalListener.java b/guava/src/com/google/common/cache/RemovalListener.java
index c9a343c44d0c..4713be57214f 100644
--- a/guava/src/com/google/common/cache/RemovalListener.java
+++ b/guava/src/com/google/common/cache/RemovalListener.java
@@ -34,6 +34,7 @@
  */
 @GwtCompatible
 @FunctionalInterface
+@ElementTypesAreNonnullByDefault
 public interface RemovalListener<K, V> {
   /**
    * Notifies the listener that a removal occurred at some point in the past.
diff --git a/guava/src/com/google/common/cache/RemovalListeners.java b/guava/src/com/google/common/cache/RemovalListeners.java
index c82b0941207f..38edf35287af 100644
--- a/guava/src/com/google/common/cache/RemovalListeners.java
+++ b/guava/src/com/google/common/cache/RemovalListeners.java
@@ -26,6 +26,7 @@
  * @since 10.0
  */
 @GwtIncompatible
+@ElementTypesAreNonnullByDefault
 public final class RemovalListeners {
 
   private RemovalListeners() {}
@@ -38,20 +39,10 @@ private RemovalListeners() {}
    * @param executor the executor with which removal notifications are asynchronously executed
    */
   public static <K, V> RemovalListener<K, V> asynchronous(
-      final RemovalListener<K, V> listener, final Executor executor) {
+      RemovalListener<K, V> listener, Executor executor) {
     checkNotNull(listener);
     checkNotNull(executor);
-    return new RemovalListener<K, V>() {
-      @Override
-      public void onRemoval(final RemovalNotification<K, V> notification) {
-        executor.execute(
-            new Runnable() {
-              @Override
-              public void run() {
-                listener.onRemoval(notification);
-              }
-            });
-      }
-    };
+    return (RemovalNotification<K, V> notification) ->
+        executor.execute(() -> listener.onRemoval(notification));
   }
 }
diff --git a/guava/src/com/google/common/cache/RemovalNotification.java b/guava/src/com/google/common/cache/RemovalNotification.java
index 641d18f72438..b96fc570911f 100644
--- a/guava/src/com/google/common/cache/RemovalNotification.java
+++ b/guava/src/com/google/common/cache/RemovalNotification.java
@@ -18,6 +18,7 @@
 
 import com.google.common.annotations.GwtCompatible;
 import java.util.AbstractMap.SimpleImmutableEntry;
+import javax.annotation.CheckForNull;
 import org.checkerframework.checker.nullness.qual.Nullable;
 
 /**
@@ -32,7 +33,9 @@
  * @since 10.0
  */
 @GwtCompatible
-public final class RemovalNotification<K, V> extends SimpleImmutableEntry<K, V> {
+@ElementTypesAreNonnullByDefault
+public final class RemovalNotification<K, V>
+    extends SimpleImmutableEntry<@Nullable K, @Nullable V> {
   private final RemovalCause cause;
 
   /**
@@ -43,11 +46,11 @@ public final class RemovalNotification<K, V> extends SimpleImmutableEntry<K, V>
    * @since 19.0
    */
   public static <K, V> RemovalNotification<K, V> create(
-      @Nullable K key, @Nullable V value, RemovalCause cause) {
-    return new RemovalNotification(key, value, cause);
+      @CheckForNull K key, @CheckForNull V value, RemovalCause cause) {
+    return new RemovalNotification<>(key, value, cause);
   }
 
-  private RemovalNotification(@Nullable K key, @Nullable V value, RemovalCause cause) {
+  private RemovalNotification(@CheckForNull K key, @CheckForNull V value, RemovalCause cause) {
     super(key, value);
     this.cause = checkNotNull(cause);
   }
diff --git a/guava/src/com/google/common/cache/Striped64.java b/guava/src/com/google/common/cache/Striped64.java
index 8c53158eb1d3..0d2d75b9f384 100644
--- a/guava/src/com/google/common/cache/Striped64.java
+++ b/guava/src/com/google/common/cache/Striped64.java
@@ -13,6 +13,7 @@
 
 import com.google.common.annotations.GwtIncompatible;
 import java.util.Random;
+import javax.annotation.CheckForNull;
 import org.checkerframework.checker.nullness.qual.Nullable;
 
 /**
@@ -21,6 +22,7 @@
  * so.
  */
 @GwtIncompatible
+@ElementTypesAreNonnullByDefault
 abstract class Striped64 extends Number {
   /*
    * This class maintains a lazily-initialized table of atomically
@@ -125,7 +127,7 @@ final boolean cas(long cmp, long val) {
    * class, we use a suboptimal int[] representation to avoid introducing a new type that can impede
    * class-unloading when ThreadLocals are not removed.
    */
-  static final ThreadLocal<int[]> threadHashCode = new ThreadLocal<>();
+  static final ThreadLocal<int @Nullable []> threadHashCode = new ThreadLocal<>();
 
   /** Generator of new random hash codes */
   static final Random rng = new Random();
@@ -134,7 +136,7 @@ final boolean cas(long cmp, long val) {
   static final int NCPU = Runtime.getRuntime().availableProcessors();
 
   /** Table of cells. When non-null, size is a power of 2. */
-  transient volatile Cell @Nullable [] cells;
+  @CheckForNull transient volatile Cell[] cells;
 
   /**
    * Base value, used mainly when there is no contention, but also as a fallback during table
@@ -177,7 +179,7 @@ final boolean casBusy() {
    * @param hc the hash code holder
    * @param wasUncontended false if CAS failed before call
    */
-  final void retryUpdate(long x, int[] hc, boolean wasUncontended) {
+  final void retryUpdate(long x, @CheckForNull int[] hc, boolean wasUncontended) {
     int h;
     if (hc == null) {
       threadHashCode.set(hc = new int[1]); // Initialize randomly
diff --git a/guava/src/com/google/common/cache/Weigher.java b/guava/src/com/google/common/cache/Weigher.java
index 7372a46965ce..bbee3f585ec4 100644
--- a/guava/src/com/google/common/cache/Weigher.java
+++ b/guava/src/com/google/common/cache/Weigher.java
@@ -24,6 +24,7 @@
  */
 @GwtCompatible
 @FunctionalInterface
+@ElementTypesAreNonnullByDefault
 public interface Weigher<K, V> {
 
   /**
diff --git a/guava/src/com/google/common/collect/AbstractBiMap.java b/guava/src/com/google/common/collect/AbstractBiMap.java
index f9b55daa56ca..d52dc61ae022 100644
--- a/guava/src/com/google/common/collect/AbstractBiMap.java
+++ b/guava/src/com/google/common/collect/AbstractBiMap.java
@@ -18,7 +18,7 @@
 
 import static com.google.common.base.Preconditions.checkArgument;
 import static com.google.common.base.Preconditions.checkState;
-import static com.google.common.collect.CollectPreconditions.checkRemove;
+import static com.google.common.collect.NullnessCasts.uncheckedCastNullableTToT;
 
 import com.google.common.annotations.GwtCompatible;
 import com.google.common.annotations.GwtIncompatible;
@@ -35,6 +35,7 @@
 import java.util.Map;
 import java.util.Set;
 import java.util.function.BiFunction;
+import javax.annotation.CheckForNull;
 import org.checkerframework.checker.nullness.qual.Nullable;
 import org.checkerframework.dataflow.qual.Pure;
 import org.checkerframework.dataflow.qual.SideEffectFree;
@@ -51,11 +52,12 @@
  */
 @AnnotatedFor({"nullness"})
 @GwtCompatible(emulated = true)
-abstract class AbstractBiMap<K, V> extends ForwardingMap<K, V>
-    implements BiMap<K, V>, Serializable {
+@ElementTypesAreNonnullByDefault
+abstract class AbstractBiMap<K extends @Nullable Object, V extends @Nullable Object>
+    extends ForwardingMap<K, V> implements BiMap<K, V>, Serializable {
 
-  private transient @Nullable Map<K, V> delegate;
-  @RetainedWith transient @Nullable AbstractBiMap<V, K> inverse;
+  private transient Map<K, V> delegate;
+  @RetainedWith transient AbstractBiMap<V, K> inverse;
 
   /** Package-private constructor for creating a map-backed bimap. */
   AbstractBiMap(Map<K, V> forward, Map<V, K> backward) {
@@ -75,13 +77,15 @@ protected Map<K, V> delegate() {
 
   /** Returns its input, or throws an exception if this is not a valid key. */
   @CanIgnoreReturnValue
-  K checkKey(@Nullable K key) {
+  @ParametricNullness
+  K checkKey(@ParametricNullness K key) {
     return key;
   }
 
   /** Returns its input, or throws an exception if this is not a valid value. */
   @CanIgnoreReturnValue
-  V checkValue(@Nullable V value) {
+  @ParametricNullness
+  V checkValue(@ParametricNullness V value) {
     return value;
   }
 
@@ -111,7 +115,7 @@ void setInverse(AbstractBiMap<V, K> inverse) {
 
   @Pure
   @Override
-  public boolean containsValue(@Nullable Object value) {
+  public boolean containsValue(@CheckForNull Object value) {
     return inverse.containsKey(value);
   }
 
@@ -119,17 +123,20 @@ public boolean containsValue(@Nullable Object value) {
 
   @CanIgnoreReturnValue
   @Override
-  public V put(@Nullable K key, @Nullable V value) {
+  @CheckForNull
+  public V put(@ParametricNullness K key, @ParametricNullness V value) {
     return putInBothMaps(key, value, false);
   }
 
   @CanIgnoreReturnValue
   @Override
-  public V forcePut(@Nullable K key, @Nullable V value) {
+  @CheckForNull
+  public V forcePut(@ParametricNullness K key, @ParametricNullness V value) {
     return putInBothMaps(key, value, true);
   }
 
-  private V putInBothMaps(@Nullable K key, @Nullable V value, boolean force) {
+  @CheckForNull
+  private V putInBothMaps(@ParametricNullness K key, @ParametricNullness V value, boolean force) {
     checkKey(key);
     checkValue(value);
     boolean containedKey = containsKey(key);
@@ -146,27 +153,35 @@ private V putInBothMaps(@Nullable K key, @Nullable V value, boolean force) {
     return oldValue;
   }
 
-  private void updateInverseMap(K key, boolean containedKey, V oldValue, V newValue) {
+  private void updateInverseMap(
+      @ParametricNullness K key,
+      boolean containedKey,
+      @CheckForNull V oldValue,
+      @ParametricNullness V newValue) {
     if (containedKey) {
-      removeFromInverseMap(oldValue);
+      // The cast is safe because of the containedKey check.
+      removeFromInverseMap(uncheckedCastNullableTToT(oldValue));
     }
     inverse.delegate.put(newValue, key);
   }
 
   @CanIgnoreReturnValue
   @Override
-  public @Nullable V remove(@Nullable Object key) {
+  @CheckForNull
+  public V remove(@CheckForNull Object key) {
     return containsKey(key) ? removeFromBothMaps(key) : null;
   }
 
   @CanIgnoreReturnValue
-  private V removeFromBothMaps(@Nullable Object key) {
-    V oldValue = delegate.remove(key);
+  @ParametricNullness
+  private V removeFromBothMaps(@CheckForNull Object key) {
+    // The cast is safe because the callers of this method first check that the key is present.
+    V oldValue = uncheckedCastNullableTToT(delegate.remove(key));
     removeFromInverseMap(oldValue);
     return oldValue;
   }
 
-  private void removeFromInverseMap(@Nullable V oldValue) {
+  private void removeFromInverseMap(@ParametricNullness V oldValue) {
     inverse.delegate.remove(oldValue);
   }
 
@@ -215,7 +230,7 @@ public BiMap<V, K> inverse() {
     return inverse;
   }
 
-  private transient @Nullable Set<K> keySet;
+  @CheckForNull private transient Set<K> keySet;
 
   @SideEffectFree
   @Override
@@ -237,7 +252,7 @@ public void clear() {
     }
 
     @Override
-    public boolean remove(@Nullable Object key) {
+    public boolean remove(@CheckForNull Object key) {
       if (!contains(key)) {
         return false;
       }
@@ -261,7 +276,7 @@ public Iterator<K> iterator() {
     }
   }
 
-  private transient @Nullable Set<V> valueSet;
+  @CheckForNull private transient Set<V> valueSet;
 
   @SideEffectFree
   @Override
@@ -289,12 +304,13 @@ public Iterator<V> iterator() {
     }
 
     @Override
-    public Object[] toArray() {
+    public @Nullable Object[] toArray() {
       return standardToArray();
     }
 
     @Override
-    public <T> T[] toArray(T[] array) {
+    @SuppressWarnings("nullness") // bug in our checker's handling of toArray signatures
+    public <T extends @Nullable Object> T[] toArray(T[] array) {
       return standardToArray(array);
     }
 
@@ -305,7 +321,7 @@ public String toString() {
     }
   }
 
-  private transient @Nullable Set<Entry<K, V>> entrySet;
+  @CheckForNull private transient Set<Entry<K, V>> entrySet;
 
   @SideEffectFree
   @Override
@@ -346,7 +362,7 @@ public V setValue(V value) {
   Iterator<Entry<K, V>> entrySetIterator() {
     final Iterator<Entry<K, V>> iterator = delegate.entrySet().iterator();
     return new Iterator<Entry<K, V>>() {
-      @Nullable Entry<K, V> entry;
+      @CheckForNull Entry<K, V> entry;
 
       @Override
       public boolean hasNext() {
@@ -361,7 +377,9 @@ public Entry<K, V> next() {
 
       @Override
       public void remove() {
-        checkRemove(entry != null);
+        if (entry == null) {
+          throw new IllegalStateException("no calls to next() since the last call to remove()");
+        }
         V value = entry.getValue();
         iterator.remove();
         removeFromInverseMap(value);
@@ -385,12 +403,15 @@ public void clear() {
     }
 
     @Override
-    public boolean remove(@Nullable Object object) {
-      if (!esDelegate.contains(object)) {
+    public boolean remove(@CheckForNull Object object) {
+      /*
+       * `o instanceof Entry` is guaranteed by `contains`, but we check it here to satisfy our
+       * nullness checker.
+       */
+      if (!esDelegate.contains(object) || !(object instanceof Entry)) {
         return false;
       }
 
-      // safe because esDelegate.contains(object).
       Entry<?, ?> entry = (Entry<?, ?>) object;
       inverse.delegate.remove(entry.getValue());
       /*
@@ -411,17 +432,25 @@ public Iterator<Entry<K, V>> iterator() {
 
     @Override
     public Object[] toArray() {
-      return standardToArray();
+      /*
+       * standardToArray returns `@Nullable Object[]` rather than `Object[]` but only because it can
+       * be used with collections that may contain null. This collection never contains nulls, so we
+       * can treat it as a plain `Object[]`.
+       */
+      @SuppressWarnings("nullness")
+      Object[] result = standardToArray();
+      return result;
     }
 
     @Override
-    public <T> T[] toArray(T[] array) {
+    @SuppressWarnings("nullness") // bug in our checker's handling of toArray signatures
+    public <T extends @Nullable Object> T[] toArray(T[] array) {
       return standardToArray(array);
     }
 
     @Pure
     @Override
-    public boolean contains(@Nullable Object o) {
+    public boolean contains(@CheckForNull Object o) {
       return Maps.containsEntryImpl(delegate(), o);
     }
 
@@ -443,7 +472,8 @@ public boolean retainAll(Collection<?> c) {
   }
 
   /** The inverse of any other {@code AbstractBiMap} subclass. */
-  static class Inverse<K, V> extends AbstractBiMap<K, V> {
+  static class Inverse<K extends @Nullable Object, V extends @Nullable Object>
+      extends AbstractBiMap<K, V> {
     Inverse(Map<K, V> backward, AbstractBiMap<V, K> forward) {
       super(backward, forward);
     }
@@ -458,12 +488,14 @@ static class Inverse<K, V> extends AbstractBiMap<K, V> {
      */
 
     @Override
-    K checkKey(K key) {
+    @ParametricNullness
+    K checkKey(@ParametricNullness K key) {
       return inverse.checkValue(key);
     }
 
     @Override
-    V checkValue(V value) {
+    @ParametricNullness
+    V checkValue(@ParametricNullness V value) {
       return inverse.checkKey(value);
     }
 
diff --git a/guava/src/com/google/common/collect/AbstractIndexedListIterator.java b/guava/src/com/google/common/collect/AbstractIndexedListIterator.java
index 855fb1c5fd0b..abb3960b261e 100644
--- a/guava/src/com/google/common/collect/AbstractIndexedListIterator.java
+++ b/guava/src/com/google/common/collect/AbstractIndexedListIterator.java
@@ -21,6 +21,7 @@
 import com.google.common.annotations.GwtCompatible;
 import java.util.ListIterator;
 import java.util.NoSuchElementException;
+import org.checkerframework.checker.nullness.qual.Nullable;
 
 /**
  * This class provides a skeletal implementation of the {@link ListIterator} interface across a
@@ -30,11 +31,14 @@
  * @author Jared Levy
  */
 @GwtCompatible
-abstract class AbstractIndexedListIterator<E> extends UnmodifiableListIterator<E> {
+@ElementTypesAreNonnullByDefault
+abstract class AbstractIndexedListIterator<E extends @Nullable Object>
+    extends UnmodifiableListIterator<E> {
   private final int size;
   private int position;
 
   /** Returns the element with the specified index. This method is called by {@link #next()}. */
+  @ParametricNullness
   protected abstract E get(int index);
 
   /**
@@ -70,6 +74,7 @@ public final boolean hasNext() {
   }
 
   @Override
+  @ParametricNullness
   public final E next() {
     if (!hasNext()) {
       throw new NoSuchElementException();
@@ -88,6 +93,7 @@ public final boolean hasPrevious() {
   }
 
   @Override
+  @ParametricNullness
   public final E previous() {
     if (!hasPrevious()) {
       throw new NoSuchElementException();
diff --git a/guava/src/com/google/common/collect/AbstractIterator.java b/guava/src/com/google/common/collect/AbstractIterator.java
index df2de8f5f9a6..1db85d67351a 100644
--- a/guava/src/com/google/common/collect/AbstractIterator.java
+++ b/guava/src/com/google/common/collect/AbstractIterator.java
@@ -17,10 +17,12 @@
 package com.google.common.collect;
 
 import static com.google.common.base.Preconditions.checkState;
+import static com.google.common.collect.NullnessCasts.uncheckedCastNullableTToT;
 
 import com.google.common.annotations.GwtCompatible;
 import com.google.errorprone.annotations.CanIgnoreReturnValue;
 import java.util.NoSuchElementException;
+import javax.annotation.CheckForNull;
 import org.checkerframework.checker.nullness.qual.Nullable;
 import org.checkerframework.framework.qual.AnnotatedFor;
 
@@ -63,7 +65,8 @@
 // com.google.common.base.AbstractIterator
 @AnnotatedFor({"nullness"})
 @GwtCompatible
-public abstract class AbstractIterator<T> extends UnmodifiableIterator<T> {
+@ElementTypesAreNonnullByDefault
+public abstract class AbstractIterator<T extends @Nullable Object> extends UnmodifiableIterator<T> {
   private State state = State.NOT_READY;
 
   /** Constructor for use by subclasses. */
@@ -83,7 +86,7 @@ private enum State {
     FAILED,
   }
 
-  private @Nullable T next;
+  @CheckForNull private T next;
 
   /**
    * Returns the next element. <b>Note:</b> the implementation must call {@link #endOfData()} when
@@ -109,6 +112,7 @@ private enum State {
    *     this method. Any further attempts to use the iterator will result in an {@link
    *     IllegalStateException}.
    */
+  @CheckForNull
   protected abstract T computeNext();
 
   /**
@@ -119,6 +123,7 @@ private enum State {
    *     simple statement {@code return endOfData();}
    */
   @CanIgnoreReturnValue
+  @CheckForNull
   protected final T endOfData() {
     state = State.DONE;
     return null;
@@ -150,12 +155,14 @@ private boolean tryToComputeNext() {
 
   @CanIgnoreReturnValue // TODO(kak): Should we remove this?
   @Override
+  @ParametricNullness
   public final T next() {
     if (!hasNext()) {
       throw new NoSuchElementException();
     }
     state = State.NOT_READY;
-    T result = next;
+    // Safe because hasNext() ensures that tryToComputeNext() has put a T into `next`.
+    T result = uncheckedCastNullableTToT(next);
     next = null;
     return result;
   }
@@ -167,10 +174,12 @@ public final T next() {
    * <p>Implementations of {@code AbstractIterator} that wish to expose this functionality should
    * implement {@code PeekingIterator}.
    */
+  @ParametricNullness
   public final T peek() {
     if (!hasNext()) {
       throw new NoSuchElementException();
     }
-    return next;
+    // Safe because hasNext() ensures that tryToComputeNext() has put a T into `next`.
+    return uncheckedCastNullableTToT(next);
   }
 }
diff --git a/guava/src/com/google/common/collect/AbstractListMultimap.java b/guava/src/com/google/common/collect/AbstractListMultimap.java
index 193091ca7ebc..35cb3322fbe1 100644
--- a/guava/src/com/google/common/collect/AbstractListMultimap.java
+++ b/guava/src/com/google/common/collect/AbstractListMultimap.java
@@ -22,6 +22,7 @@
 import java.util.Collections;
 import java.util.List;
 import java.util.Map;
+import javax.annotation.CheckForNull;
 import org.checkerframework.checker.nullness.qual.Nullable;
 import org.checkerframework.dataflow.qual.Pure;
 import org.checkerframework.framework.qual.AnnotatedFor;
@@ -36,8 +37,9 @@
  */
 @AnnotatedFor({"nullness"})
 @GwtCompatible
-abstract class AbstractListMultimap<K, V> extends AbstractMapBasedMultimap<K, V>
-    implements ListMultimap<K, V> {
+@ElementTypesAreNonnullByDefault
+abstract class AbstractListMultimap<K extends @Nullable Object, V extends @Nullable Object>
+    extends AbstractMapBasedMultimap<K, V> implements ListMultimap<K, V> {
   /**
    * Creates a new multimap that uses the provided map.
    *
@@ -56,12 +58,13 @@ List<V> createUnmodifiableEmptyCollection() {
   }
 
   @Override
-  <E> Collection<E> unmodifiableCollectionSubclass(Collection<E> collection) {
+  <E extends @Nullable Object> Collection<E> unmodifiableCollectionSubclass(
+      Collection<E> collection) {
     return Collections.unmodifiableList((List<E>) collection);
   }
 
   @Override
-  Collection<V> wrapCollection(K key, Collection<V> collection) {
+  Collection<V> wrapCollection(@ParametricNullness K key, Collection<V> collection) {
     return wrapList(key, (List<V>) collection, null);
   }
 
@@ -75,7 +78,7 @@ Collection<V> wrapCollection(K key, Collection<V> collection) {
    * Multimap} interface.
    */
   @Override
-  public List<V> get(@Nullable K key) {
+  public List<V> get(@ParametricNullness K key) {
     return (List<V>) super.get(key);
   }
 
@@ -88,7 +91,7 @@ public List<V> get(@Nullable K key) {
    */
   @CanIgnoreReturnValue
   @Override
-  public List<V> removeAll(@Nullable Object key) {
+  public List<V> removeAll(@CheckForNull Object key) {
     return (List<V>) super.removeAll(key);
   }
 
@@ -101,7 +104,7 @@ public List<V> removeAll(@Nullable Object key) {
    */
   @CanIgnoreReturnValue
   @Override
-  public List<V> replaceValues(@Nullable K key, Iterable<? extends V> values) {
+  public List<V> replaceValues(@ParametricNullness K key, Iterable<? extends V> values) {
     return (List<V>) super.replaceValues(key, values);
   }
 
@@ -114,7 +117,7 @@ public List<V> replaceValues(@Nullable K key, Iterable<? extends V> values) {
    */
   @CanIgnoreReturnValue
   @Override
-  public boolean put(@Nullable K key, @Nullable V value) {
+  public boolean put(@ParametricNullness K key, @ParametricNullness V value) {
     return super.put(key, value);
   }
 
@@ -137,7 +140,7 @@ public Map<K, Collection<V>> asMap() {
    */
   @Pure
   @Override
-  public boolean equals(@Nullable Object object) {
+  public boolean equals(@CheckForNull Object object) {
     return super.equals(object);
   }
 
diff --git a/guava/src/com/google/common/collect/AbstractMapBasedMultimap.java b/guava/src/com/google/common/collect/AbstractMapBasedMultimap.java
index b9f46ed743cc..4c5a0f0418fb 100644
--- a/guava/src/com/google/common/collect/AbstractMapBasedMultimap.java
+++ b/guava/src/com/google/common/collect/AbstractMapBasedMultimap.java
@@ -18,7 +18,9 @@
 
 import static com.google.common.base.Preconditions.checkArgument;
 import static com.google.common.base.Preconditions.checkNotNull;
-import static com.google.common.collect.CollectPreconditions.checkRemove;
+import static com.google.common.base.Preconditions.checkState;
+import static com.google.common.collect.NullnessCasts.uncheckedCastNullableTToT;
+import static java.util.Objects.requireNonNull;
 
 import com.google.common.annotations.GwtCompatible;
 import com.google.common.collect.Maps.ViewCachingAbstractMap;
@@ -42,6 +44,7 @@
 import java.util.SortedSet;
 import java.util.Spliterator;
 import java.util.function.BiConsumer;
+import javax.annotation.CheckForNull;
 import org.checkerframework.checker.nullness.qual.Nullable;
 
 /**
@@ -83,8 +86,9 @@
  * @author Louis Wasserman
  */
 @GwtCompatible
-abstract class AbstractMapBasedMultimap<K, V> extends AbstractMultimap<K, V>
-    implements Serializable {
+@ElementTypesAreNonnullByDefault
+abstract class AbstractMapBasedMultimap<K extends @Nullable Object, V extends @Nullable Object>
+    extends AbstractMultimap<K, V> implements Serializable {
   /*
    * Here's an outline of the overall design.
    *
@@ -157,7 +161,7 @@ Collection<V> createUnmodifiableEmptyCollection() {
    * @param key key to associate with values in the collection
    * @return an empty collection of values
    */
-  Collection<V> createCollection(@Nullable K key) {
+  Collection<V> createCollection(@ParametricNullness K key) {
     return createCollection();
   }
 
@@ -173,14 +177,14 @@ public int size() {
   }
 
   @Override
-  public boolean containsKey(@Nullable Object key) {
+  public boolean containsKey(@CheckForNull Object key) {
     return map.containsKey(key);
   }
 
   // Modification Operations
 
   @Override
-  public boolean put(@Nullable K key, @Nullable V value) {
+  public boolean put(@ParametricNullness K key, @ParametricNullness V value) {
     Collection<V> collection = map.get(key);
     if (collection == null) {
       collection = createCollection(key);
@@ -199,7 +203,7 @@ public boolean put(@Nullable K key, @Nullable V value) {
     }
   }
 
-  private Collection<V> getOrCreateCollection(@Nullable K key) {
+  private Collection<V> getOrCreateCollection(@ParametricNullness K key) {
     Collection<V> collection = map.get(key);
     if (collection == null) {
       collection = createCollection(key);
@@ -216,7 +220,7 @@ private Collection<V> getOrCreateCollection(@Nullable K key) {
    * <p>The returned collection is immutable.
    */
   @Override
-  public Collection<V> replaceValues(@Nullable K key, Iterable<? extends V> values) {
+  public Collection<V> replaceValues(@ParametricNullness K key, Iterable<? extends V> values) {
     Iterator<? extends V> iterator = values.iterator();
     if (!iterator.hasNext()) {
       return removeAll(key);
@@ -245,7 +249,7 @@ public Collection<V> replaceValues(@Nullable K key, Iterable<? extends V> values
    * <p>The returned collection is immutable.
    */
   @Override
-  public Collection<V> removeAll(@Nullable Object key) {
+  public Collection<V> removeAll(@CheckForNull Object key) {
     Collection<V> collection = map.remove(key);
 
     if (collection == null) {
@@ -260,7 +264,8 @@ public Collection<V> removeAll(@Nullable Object key) {
     return unmodifiableCollectionSubclass(output);
   }
 
-  <E> Collection<E> unmodifiableCollectionSubclass(Collection<E> collection) {
+  <E extends @Nullable Object> Collection<E> unmodifiableCollectionSubclass(
+      Collection<E> collection) {
     return Collections.unmodifiableCollection(collection);
   }
 
@@ -282,7 +287,7 @@ public void clear() {
    * <p>The returned collection is not serializable.
    */
   @Override
-  public Collection<V> get(@Nullable K key) {
+  public Collection<V> get(@ParametricNullness K key) {
     Collection<V> collection = map.get(key);
     if (collection == null) {
       collection = createCollection(key);
@@ -294,11 +299,12 @@ public Collection<V> get(@Nullable K key) {
    * Generates a decorated collection that remains consistent with the values in the multimap for
    * the provided key. Changes to the multimap may alter the returned collection, and vice versa.
    */
-  Collection<V> wrapCollection(@Nullable K key, Collection<V> collection) {
+  Collection<V> wrapCollection(@ParametricNullness K key, Collection<V> collection) {
     return new WrappedCollection(key, collection, null);
   }
 
-  final List<V> wrapList(@Nullable K key, List<V> list, @Nullable WrappedCollection ancestor) {
+  final List<V> wrapList(
+      @ParametricNullness K key, List<V> list, @CheckForNull WrappedCollection ancestor) {
     return (list instanceof RandomAccess)
         ? new RandomAccessWrappedList(key, list, ancestor)
         : new WrappedList(key, list, ancestor);
@@ -321,13 +327,15 @@ final List<V> wrapList(@Nullable K key, List<V> list, @Nullable WrappedCollectio
    */
   @WeakOuter
   class WrappedCollection extends AbstractCollection<V> {
-    final @Nullable K key;
+    @ParametricNullness final K key;
     Collection<V> delegate;
-    final @Nullable WrappedCollection ancestor;
-    final @Nullable Collection<V> ancestorDelegate;
+    @CheckForNull final WrappedCollection ancestor;
+    @CheckForNull final Collection<V> ancestorDelegate;
 
     WrappedCollection(
-        @Nullable K key, Collection<V> delegate, @Nullable WrappedCollection ancestor) {
+        @ParametricNullness K key,
+        Collection<V> delegate,
+        @CheckForNull WrappedCollection ancestor) {
       this.key = key;
       this.delegate = delegate;
       this.ancestor = ancestor;
@@ -367,6 +375,7 @@ void removeIfEmpty() {
       }
     }
 
+    @ParametricNullness
     K getKey() {
       return key;
     }
@@ -392,7 +401,7 @@ public int size() {
     }
 
     @Override
-    public boolean equals(@Nullable Object object) {
+    public boolean equals(@CheckForNull Object object) {
       if (object == this) {
         return true;
       }
@@ -458,6 +467,7 @@ public boolean hasNext() {
       }
 
       @Override
+      @ParametricNullness
       public V next() {
         validateIterator();
         return delegateIterator.next();
@@ -477,7 +487,7 @@ Iterator<V> getDelegateIterator() {
     }
 
     @Override
-    public boolean add(V value) {
+    public boolean add(@ParametricNullness V value) {
       refreshIfEmpty();
       boolean wasEmpty = delegate.isEmpty();
       boolean changed = delegate.add(value);
@@ -490,6 +500,7 @@ public boolean add(V value) {
       return changed;
     }
 
+    @CheckForNull
     WrappedCollection getAncestor() {
       return ancestor;
     }
@@ -514,7 +525,7 @@ public boolean addAll(Collection<? extends V> collection) {
     }
 
     @Override
-    public boolean contains(Object o) {
+    public boolean contains(@CheckForNull Object o) {
       refreshIfEmpty();
       return delegate.contains(o);
     }
@@ -537,7 +548,7 @@ public void clear() {
     }
 
     @Override
-    public boolean remove(Object o) {
+    public boolean remove(@CheckForNull Object o) {
       refreshIfEmpty();
       boolean changed = delegate.remove(o);
       if (changed) {
@@ -576,7 +587,8 @@ public boolean retainAll(Collection<?> c) {
     }
   }
 
-  private static <E> Iterator<E> iteratorOrListIterator(Collection<E> collection) {
+  private static <E extends @Nullable Object> Iterator<E> iteratorOrListIterator(
+      Collection<E> collection) {
     return (collection instanceof List)
         ? ((List<E>) collection).listIterator()
         : collection.iterator();
@@ -585,7 +597,7 @@ private static <E> Iterator<E> iteratorOrListIterator(Collection<E> collection)
   /** Set decorator that stays in sync with the multimap values for a key. */
   @WeakOuter
   class WrappedSet extends WrappedCollection implements Set<V> {
-    WrappedSet(@Nullable K key, Set<V> delegate) {
+    WrappedSet(@ParametricNullness K key, Set<V> delegate) {
       super(key, delegate, null);
     }
 
@@ -612,7 +624,10 @@ public boolean removeAll(Collection<?> c) {
   /** SortedSet decorator that stays in sync with the multimap values for a key. */
   @WeakOuter
   class WrappedSortedSet extends WrappedCollection implements SortedSet<V> {
-    WrappedSortedSet(@Nullable K key, SortedSet<V> delegate, @Nullable WrappedCollection ancestor) {
+    WrappedSortedSet(
+        @ParametricNullness K key,
+        SortedSet<V> delegate,
+        @CheckForNull WrappedCollection ancestor) {
       super(key, delegate, ancestor);
     }
 
@@ -621,24 +636,27 @@ SortedSet<V> getSortedSetDelegate() {
     }
 
     @Override
+    @CheckForNull
     public Comparator<? super V> comparator() {
       return getSortedSetDelegate().comparator();
     }
 
     @Override
+    @ParametricNullness
     public V first() {
       refreshIfEmpty();
       return getSortedSetDelegate().first();
     }
 
     @Override
+    @ParametricNullness
     public V last() {
       refreshIfEmpty();
       return getSortedSetDelegate().last();
     }
 
     @Override
-    public SortedSet<V> headSet(V toElement) {
+    public SortedSet<V> headSet(@ParametricNullness V toElement) {
       refreshIfEmpty();
       return new WrappedSortedSet(
           getKey(),
@@ -647,7 +665,7 @@ public SortedSet<V> headSet(V toElement) {
     }
 
     @Override
-    public SortedSet<V> subSet(V fromElement, V toElement) {
+    public SortedSet<V> subSet(@ParametricNullness V fromElement, @ParametricNullness V toElement) {
       refreshIfEmpty();
       return new WrappedSortedSet(
           getKey(),
@@ -656,7 +674,7 @@ public SortedSet<V> subSet(V fromElement, V toElement) {
     }
 
     @Override
-    public SortedSet<V> tailSet(V fromElement) {
+    public SortedSet<V> tailSet(@ParametricNullness V fromElement) {
       refreshIfEmpty();
       return new WrappedSortedSet(
           getKey(),
@@ -668,7 +686,9 @@ public SortedSet<V> tailSet(V fromElement) {
   @WeakOuter
   class WrappedNavigableSet extends WrappedSortedSet implements NavigableSet<V> {
     WrappedNavigableSet(
-        @Nullable K key, NavigableSet<V> delegate, @Nullable WrappedCollection ancestor) {
+        @ParametricNullness K key,
+        NavigableSet<V> delegate,
+        @CheckForNull WrappedCollection ancestor) {
       super(key, delegate, ancestor);
     }
 
@@ -678,31 +698,37 @@ NavigableSet<V> getSortedSetDelegate() {
     }
 
     @Override
-    public V lower(V v) {
+    @CheckForNull
+    public V lower(@ParametricNullness V v) {
       return getSortedSetDelegate().lower(v);
     }
 
     @Override
-    public V floor(V v) {
+    @CheckForNull
+    public V floor(@ParametricNullness V v) {
       return getSortedSetDelegate().floor(v);
     }
 
     @Override
-    public V ceiling(V v) {
+    @CheckForNull
+    public V ceiling(@ParametricNullness V v) {
       return getSortedSetDelegate().ceiling(v);
     }
 
     @Override
-    public V higher(V v) {
+    @CheckForNull
+    public V higher(@ParametricNullness V v) {
       return getSortedSetDelegate().higher(v);
     }
 
     @Override
+    @CheckForNull
     public V pollFirst() {
       return Iterators.pollNext(iterator());
     }
 
     @Override
+    @CheckForNull
     public V pollLast() {
       return Iterators.pollNext(descendingIterator());
     }
@@ -723,18 +749,21 @@ public Iterator<V> descendingIterator() {
 
     @Override
     public NavigableSet<V> subSet(
-        V fromElement, boolean fromInclusive, V toElement, boolean toInclusive) {
+        @ParametricNullness V fromElement,
+        boolean fromInclusive,
+        @ParametricNullness V toElement,
+        boolean toInclusive) {
       return wrap(
           getSortedSetDelegate().subSet(fromElement, fromInclusive, toElement, toInclusive));
     }
 
     @Override
-    public NavigableSet<V> headSet(V toElement, boolean inclusive) {
+    public NavigableSet<V> headSet(@ParametricNullness V toElement, boolean inclusive) {
       return wrap(getSortedSetDelegate().headSet(toElement, inclusive));
     }
 
     @Override
-    public NavigableSet<V> tailSet(V fromElement, boolean inclusive) {
+    public NavigableSet<V> tailSet(@ParametricNullness V fromElement, boolean inclusive) {
       return wrap(getSortedSetDelegate().tailSet(fromElement, inclusive));
     }
   }
@@ -742,7 +771,8 @@ public NavigableSet<V> tailSet(V fromElement, boolean inclusive) {
   /** List decorator that stays in sync with the multimap values for a key. */
   @WeakOuter
   class WrappedList extends WrappedCollection implements List<V> {
-    WrappedList(@Nullable K key, List<V> delegate, @Nullable WrappedCollection ancestor) {
+    WrappedList(
+        @ParametricNullness K key, List<V> delegate, @CheckForNull WrappedCollection ancestor) {
       super(key, delegate, ancestor);
     }
 
@@ -768,19 +798,21 @@ public boolean addAll(int index, Collection<? extends V> c) {
     }
 
     @Override
+    @ParametricNullness
     public V get(int index) {
       refreshIfEmpty();
       return getListDelegate().get(index);
     }
 
     @Override
-    public V set(int index, V element) {
+    @ParametricNullness
+    public V set(int index, @ParametricNullness V element) {
       refreshIfEmpty();
       return getListDelegate().set(index, element);
     }
 
     @Override
-    public void add(int index, V element) {
+    public void add(int index, @ParametricNullness V element) {
       refreshIfEmpty();
       boolean wasEmpty = getDelegate().isEmpty();
       getListDelegate().add(index, element);
@@ -791,6 +823,7 @@ public void add(int index, V element) {
     }
 
     @Override
+    @ParametricNullness
     public V remove(int index) {
       refreshIfEmpty();
       V value = getListDelegate().remove(index);
@@ -800,13 +833,13 @@ public V remove(int index) {
     }
 
     @Override
-    public int indexOf(Object o) {
+    public int indexOf(@CheckForNull Object o) {
       refreshIfEmpty();
       return getListDelegate().indexOf(o);
     }
 
     @Override
-    public int lastIndexOf(Object o) {
+    public int lastIndexOf(@CheckForNull Object o) {
       refreshIfEmpty();
       return getListDelegate().lastIndexOf(o);
     }
@@ -850,6 +883,7 @@ public boolean hasPrevious() {
       }
 
       @Override
+      @ParametricNullness
       public V previous() {
         return getDelegateListIterator().previous();
       }
@@ -865,12 +899,12 @@ public int previousIndex() {
       }
 
       @Override
-      public void set(V value) {
+      public void set(@ParametricNullness V value) {
         getDelegateListIterator().set(value);
       }
 
       @Override
-      public void add(V value) {
+      public void add(@ParametricNullness V value) {
         boolean wasEmpty = isEmpty();
         getDelegateListIterator().add(value);
         totalSize++;
@@ -887,7 +921,7 @@ public void add(V value) {
    */
   private class RandomAccessWrappedList extends WrappedList implements RandomAccess {
     RandomAccessWrappedList(
-        @Nullable K key, List<V> delegate, @Nullable WrappedCollection ancestor) {
+        @ParametricNullness K key, List<V> delegate, @CheckForNull WrappedCollection ancestor) {
       super(key, delegate, ancestor);
     }
   }
@@ -917,7 +951,7 @@ private class KeySet extends Maps.KeySet<K, Collection<V>> {
     public Iterator<K> iterator() {
       final Iterator<Entry<K, Collection<V>>> entryIterator = map().entrySet().iterator();
       return new Iterator<K>() {
-        @Nullable Entry<K, Collection<V>> entry;
+        @CheckForNull Entry<K, Collection<V>> entry;
 
         @Override
         public boolean hasNext() {
@@ -925,6 +959,7 @@ public boolean hasNext() {
         }
 
         @Override
+        @ParametricNullness
         public K next() {
           entry = entryIterator.next();
           return entry.getKey();
@@ -932,7 +967,7 @@ public K next() {
 
         @Override
         public void remove() {
-          checkRemove(entry != null);
+          checkState(entry != null, "no calls to next() since the last call to remove()");
           Collection<V> collection = entry.getValue();
           entryIterator.remove();
           totalSize -= collection.size();
@@ -950,7 +985,7 @@ public Spliterator<K> spliterator() {
     }
 
     @Override
-    public boolean remove(Object key) {
+    public boolean remove(@CheckForNull Object key) {
       int count = 0;
       Collection<V> collection = map().remove(key);
       if (collection != null) {
@@ -972,7 +1007,7 @@ public boolean containsAll(Collection<?> c) {
     }
 
     @Override
-    public boolean equals(@Nullable Object object) {
+    public boolean equals(@CheckForNull Object object) {
       return this == object || this.map().keySet().equals(object);
     }
 
@@ -994,32 +1029,35 @@ SortedMap<K, Collection<V>> sortedMap() {
     }
 
     @Override
+    @CheckForNull
     public Comparator<? super K> comparator() {
       return sortedMap().comparator();
     }
 
     @Override
+    @ParametricNullness
     public K first() {
       return sortedMap().firstKey();
     }
 
     @Override
-    public SortedSet<K> headSet(K toElement) {
+    public SortedSet<K> headSet(@ParametricNullness K toElement) {
       return new SortedKeySet(sortedMap().headMap(toElement));
     }
 
     @Override
+    @ParametricNullness
     public K last() {
       return sortedMap().lastKey();
     }
 
     @Override
-    public SortedSet<K> subSet(K fromElement, K toElement) {
+    public SortedSet<K> subSet(@ParametricNullness K fromElement, @ParametricNullness K toElement) {
       return new SortedKeySet(sortedMap().subMap(fromElement, toElement));
     }
 
     @Override
-    public SortedSet<K> tailSet(K fromElement) {
+    public SortedSet<K> tailSet(@ParametricNullness K fromElement) {
       return new SortedKeySet(sortedMap().tailMap(fromElement));
     }
   }
@@ -1036,31 +1074,37 @@ NavigableMap<K, Collection<V>> sortedMap() {
     }
 
     @Override
-    public K lower(K k) {
+    @CheckForNull
+    public K lower(@ParametricNullness K k) {
       return sortedMap().lowerKey(k);
     }
 
     @Override
-    public K floor(K k) {
+    @CheckForNull
+    public K floor(@ParametricNullness K k) {
       return sortedMap().floorKey(k);
     }
 
     @Override
-    public K ceiling(K k) {
+    @CheckForNull
+    public K ceiling(@ParametricNullness K k) {
       return sortedMap().ceilingKey(k);
     }
 
     @Override
-    public K higher(K k) {
+    @CheckForNull
+    public K higher(@ParametricNullness K k) {
       return sortedMap().higherKey(k);
     }
 
     @Override
+    @CheckForNull
     public K pollFirst() {
       return Iterators.pollNext(iterator());
     }
 
     @Override
+    @CheckForNull
     public K pollLast() {
       return Iterators.pollNext(descendingIterator());
     }
@@ -1076,40 +1120,44 @@ public Iterator<K> descendingIterator() {
     }
 
     @Override
-    public NavigableSet<K> headSet(K toElement) {
+    public NavigableSet<K> headSet(@ParametricNullness K toElement) {
       return headSet(toElement, false);
     }
 
     @Override
-    public NavigableSet<K> headSet(K toElement, boolean inclusive) {
+    public NavigableSet<K> headSet(@ParametricNullness K toElement, boolean inclusive) {
       return new NavigableKeySet(sortedMap().headMap(toElement, inclusive));
     }
 
     @Override
-    public NavigableSet<K> subSet(K fromElement, K toElement) {
+    public NavigableSet<K> subSet(
+        @ParametricNullness K fromElement, @ParametricNullness K toElement) {
       return subSet(fromElement, true, toElement, false);
     }
 
     @Override
     public NavigableSet<K> subSet(
-        K fromElement, boolean fromInclusive, K toElement, boolean toInclusive) {
+        @ParametricNullness K fromElement,
+        boolean fromInclusive,
+        @ParametricNullness K toElement,
+        boolean toInclusive) {
       return new NavigableKeySet(
           sortedMap().subMap(fromElement, fromInclusive, toElement, toInclusive));
     }
 
     @Override
-    public NavigableSet<K> tailSet(K fromElement) {
+    public NavigableSet<K> tailSet(@ParametricNullness K fromElement) {
       return tailSet(fromElement, true);
     }
 
     @Override
-    public NavigableSet<K> tailSet(K fromElement, boolean inclusive) {
+    public NavigableSet<K> tailSet(@ParametricNullness K fromElement, boolean inclusive) {
       return new NavigableKeySet(sortedMap().tailMap(fromElement, inclusive));
     }
   }
 
   /** Removes all values for the provided key. */
-  private void removeValuesForKey(Object key) {
+  private void removeValuesForKey(@CheckForNull Object key) {
     Collection<V> collection = Maps.safeRemove(map, key);
 
     if (collection != null) {
@@ -1119,10 +1167,10 @@ private void removeValuesForKey(Object key) {
     }
   }
 
-  private abstract class Itr<T> implements Iterator<T> {
+  private abstract class Itr<T extends @Nullable Object> implements Iterator<T> {
     final Iterator<Entry<K, Collection<V>>> keyIterator;
-    @Nullable K key;
-    @Nullable Collection<V> collection;
+    @CheckForNull K key;
+    @CheckForNull Collection<V> collection;
     Iterator<V> valueIterator;
 
     Itr() {
@@ -1132,7 +1180,7 @@ private abstract class Itr<T> implements Iterator<T> {
       valueIterator = Iterators.emptyModifiableIterator();
     }
 
-    abstract T output(K key, V value);
+    abstract T output(@ParametricNullness K key, @ParametricNullness V value);
 
     @Override
     public boolean hasNext() {
@@ -1147,13 +1195,21 @@ public T next() {
         collection = mapEntry.getValue();
         valueIterator = collection.iterator();
       }
-      return output(key, valueIterator.next());
+      /*
+       * uncheckedCastNullableTToT is safe: The first call to this method always enters the !hasNext() case and
+       * populates key, after which it's never cleared.
+       */
+      return output(uncheckedCastNullableTToT(key), valueIterator.next());
     }
 
     @Override
     public void remove() {
       valueIterator.remove();
-      if (collection.isEmpty()) {
+      /*
+       * requireNonNull is safe because we've already initialized `collection`. If we hadn't, then
+       * valueIterator.remove() would have failed.
+       */
+      if (requireNonNull(collection).isEmpty()) {
         keyIterator.remove();
       }
       totalSize--;
@@ -1180,7 +1236,8 @@ Collection<V> createValues() {
   Iterator<V> valueIterator() {
     return new Itr<V>() {
       @Override
-      V output(K key, V value) {
+      @ParametricNullness
+      V output(@ParametricNullness K key, @ParametricNullness V value) {
         return value;
       }
     };
@@ -1238,7 +1295,7 @@ Collection<Entry<K, V>> createEntries() {
   Iterator<Entry<K, V>> entryIterator() {
     return new Itr<Entry<K, V>>() {
       @Override
-      Entry<K, V> output(K key, V value) {
+      Entry<K, V> output(@ParametricNullness K key, @ParametricNullness V value) {
         return Maps.immutableEntry(key, value);
       }
     };
@@ -1300,12 +1357,13 @@ protected Set<Entry<K, Collection<V>>> createEntrySet() {
     // The following methods are included for performance.
 
     @Override
-    public boolean containsKey(Object key) {
+    public boolean containsKey(@CheckForNull Object key) {
       return Maps.safeContainsKey(submap, key);
     }
 
     @Override
-    public Collection<V> get(Object key) {
+    @CheckForNull
+    public Collection<V> get(@CheckForNull Object key) {
       Collection<V> collection = Maps.safeGet(submap, key);
       if (collection == null) {
         return null;
@@ -1326,7 +1384,8 @@ public int size() {
     }
 
     @Override
-    public Collection<V> remove(Object key) {
+    @CheckForNull
+    public Collection<V> remove(@CheckForNull Object key) {
       Collection<V> collection = submap.remove(key);
       if (collection == null) {
         return null;
@@ -1340,7 +1399,7 @@ public Collection<V> remove(Object key) {
     }
 
     @Override
-    public boolean equals(@Nullable Object object) {
+    public boolean equals(@CheckForNull Object object) {
       return this == object || submap.equals(object);
     }
 
@@ -1388,16 +1447,17 @@ public Spliterator<Entry<K, Collection<V>>> spliterator() {
       // The following methods are included for performance.
 
       @Override
-      public boolean contains(Object o) {
+      public boolean contains(@CheckForNull Object o) {
         return Collections2.safeContains(submap.entrySet(), o);
       }
 
       @Override
-      public boolean remove(Object o) {
+      public boolean remove(@CheckForNull Object o) {
         if (!contains(o)) {
           return false;
         }
-        Entry<?, ?> entry = (Entry<?, ?>) o;
+        // requireNonNull is safe because of the contains check.
+        Entry<?, ?> entry = requireNonNull((Entry<?, ?>) o);
         removeValuesForKey(entry.getKey());
         return true;
       }
@@ -1406,7 +1466,7 @@ public boolean remove(Object o) {
     /** Iterator across all keys and value collections. */
     class AsMapIterator implements Iterator<Entry<K, Collection<V>>> {
       final Iterator<Entry<K, Collection<V>>> delegateIterator = submap.entrySet().iterator();
-      @Nullable Collection<V> collection;
+      @CheckForNull Collection<V> collection;
 
       @Override
       public boolean hasNext() {
@@ -1422,7 +1482,7 @@ public Entry<K, Collection<V>> next() {
 
       @Override
       public void remove() {
-        checkRemove(collection != null);
+        checkState(collection != null, "no calls to next() since the last call to remove()");
         delegateIterator.remove();
         totalSize -= collection.size();
         collection.clear();
@@ -1442,36 +1502,40 @@ SortedMap<K, Collection<V>> sortedMap() {
     }
 
     @Override
+    @CheckForNull
     public Comparator<? super K> comparator() {
       return sortedMap().comparator();
     }
 
     @Override
+    @ParametricNullness
     public K firstKey() {
       return sortedMap().firstKey();
     }
 
     @Override
+    @ParametricNullness
     public K lastKey() {
       return sortedMap().lastKey();
     }
 
     @Override
-    public SortedMap<K, Collection<V>> headMap(K toKey) {
+    public SortedMap<K, Collection<V>> headMap(@ParametricNullness K toKey) {
       return new SortedAsMap(sortedMap().headMap(toKey));
     }
 
     @Override
-    public SortedMap<K, Collection<V>> subMap(K fromKey, K toKey) {
+    public SortedMap<K, Collection<V>> subMap(
+        @ParametricNullness K fromKey, @ParametricNullness K toKey) {
       return new SortedAsMap(sortedMap().subMap(fromKey, toKey));
     }
 
     @Override
-    public SortedMap<K, Collection<V>> tailMap(K fromKey) {
+    public SortedMap<K, Collection<V>> tailMap(@ParametricNullness K fromKey) {
       return new SortedAsMap(sortedMap().tailMap(fromKey));
     }
 
-    @Nullable SortedSet<K> sortedKeySet;
+    @CheckForNull SortedSet<K> sortedKeySet;
 
     // returns a SortedSet, even though returning a Set would be sufficient to
     // satisfy the SortedMap.keySet() interface
@@ -1499,71 +1563,84 @@ NavigableMap<K, Collection<V>> sortedMap() {
     }
 
     @Override
-    public Entry<K, Collection<V>> lowerEntry(K key) {
+    @CheckForNull
+    public Entry<K, Collection<V>> lowerEntry(@ParametricNullness K key) {
       Entry<K, Collection<V>> entry = sortedMap().lowerEntry(key);
       return (entry == null) ? null : wrapEntry(entry);
     }
 
     @Override
-    public K lowerKey(K key) {
+    @CheckForNull
+    public K lowerKey(@ParametricNullness K key) {
       return sortedMap().lowerKey(key);
     }
 
     @Override
-    public Entry<K, Collection<V>> floorEntry(K key) {
+    @CheckForNull
+    public Entry<K, Collection<V>> floorEntry(@ParametricNullness K key) {
       Entry<K, Collection<V>> entry = sortedMap().floorEntry(key);
       return (entry == null) ? null : wrapEntry(entry);
     }
 
     @Override
-    public K floorKey(K key) {
+    @CheckForNull
+    public K floorKey(@ParametricNullness K key) {
       return sortedMap().floorKey(key);
     }
 
     @Override
-    public Entry<K, Collection<V>> ceilingEntry(K key) {
+    @CheckForNull
+    public Entry<K, Collection<V>> ceilingEntry(@ParametricNullness K key) {
       Entry<K, Collection<V>> entry = sortedMap().ceilingEntry(key);
       return (entry == null) ? null : wrapEntry(entry);
     }
 
     @Override
-    public K ceilingKey(K key) {
+    @CheckForNull
+    public K ceilingKey(@ParametricNullness K key) {
       return sortedMap().ceilingKey(key);
     }
 
     @Override
-    public Entry<K, Collection<V>> higherEntry(K key) {
+    @CheckForNull
+    public Entry<K, Collection<V>> higherEntry(@ParametricNullness K key) {
       Entry<K, Collection<V>> entry = sortedMap().higherEntry(key);
       return (entry == null) ? null : wrapEntry(entry);
     }
 
     @Override
-    public K higherKey(K key) {
+    @CheckForNull
+    public K higherKey(@ParametricNullness K key) {
       return sortedMap().higherKey(key);
     }
 
     @Override
+    @CheckForNull
     public Entry<K, Collection<V>> firstEntry() {
       Entry<K, Collection<V>> entry = sortedMap().firstEntry();
       return (entry == null) ? null : wrapEntry(entry);
     }
 
     @Override
+    @CheckForNull
     public Entry<K, Collection<V>> lastEntry() {
       Entry<K, Collection<V>> entry = sortedMap().lastEntry();
       return (entry == null) ? null : wrapEntry(entry);
     }
 
     @Override
+    @CheckForNull
     public Entry<K, Collection<V>> pollFirstEntry() {
       return pollAsMapEntry(entrySet().iterator());
     }
 
     @Override
+    @CheckForNull
     public Entry<K, Collection<V>> pollLastEntry() {
       return pollAsMapEntry(descendingMap().entrySet().iterator());
     }
 
+    @CheckForNull
     Entry<K, Collection<V>> pollAsMapEntry(Iterator<Entry<K, Collection<V>>> entryIterator) {
       if (!entryIterator.hasNext()) {
         return null;
@@ -1601,33 +1678,38 @@ public NavigableSet<K> descendingKeySet() {
     }
 
     @Override
-    public NavigableMap<K, Collection<V>> subMap(K fromKey, K toKey) {
+    public NavigableMap<K, Collection<V>> subMap(
+        @ParametricNullness K fromKey, @ParametricNullness K toKey) {
       return subMap(fromKey, true, toKey, false);
     }
 
     @Override
     public NavigableMap<K, Collection<V>> subMap(
-        K fromKey, boolean fromInclusive, K toKey, boolean toInclusive) {
+        @ParametricNullness K fromKey,
+        boolean fromInclusive,
+        @ParametricNullness K toKey,
+        boolean toInclusive) {
       return new NavigableAsMap(sortedMap().subMap(fromKey, fromInclusive, toKey, toInclusive));
     }
 
     @Override
-    public NavigableMap<K, Collection<V>> headMap(K toKey) {
+    public NavigableMap<K, Collection<V>> headMap(@ParametricNullness K toKey) {
       return headMap(toKey, false);
     }
 
     @Override
-    public NavigableMap<K, Collection<V>> headMap(K toKey, boolean inclusive) {
+    public NavigableMap<K, Collection<V>> headMap(@ParametricNullness K toKey, boolean inclusive) {
       return new NavigableAsMap(sortedMap().headMap(toKey, inclusive));
     }
 
     @Override
-    public NavigableMap<K, Collection<V>> tailMap(K fromKey) {
+    public NavigableMap<K, Collection<V>> tailMap(@ParametricNullness K fromKey) {
       return tailMap(fromKey, true);
     }
 
     @Override
-    public NavigableMap<K, Collection<V>> tailMap(K fromKey, boolean inclusive) {
+    public NavigableMap<K, Collection<V>> tailMap(
+        @ParametricNullness K fromKey, boolean inclusive) {
       return new NavigableAsMap(sortedMap().tailMap(fromKey, inclusive));
     }
   }
diff --git a/guava/src/com/google/common/collect/AbstractMapBasedMultiset.java b/guava/src/com/google/common/collect/AbstractMapBasedMultiset.java
index d75642834794..b754e864e697 100644
--- a/guava/src/com/google/common/collect/AbstractMapBasedMultiset.java
+++ b/guava/src/com/google/common/collect/AbstractMapBasedMultiset.java
@@ -18,8 +18,10 @@
 
 import static com.google.common.base.Preconditions.checkArgument;
 import static com.google.common.base.Preconditions.checkNotNull;
+import static com.google.common.base.Preconditions.checkState;
 import static com.google.common.collect.CollectPreconditions.checkNonnegative;
 import static com.google.common.collect.CollectPreconditions.checkRemove;
+import static java.util.Objects.requireNonNull;
 
 import com.google.common.annotations.GwtCompatible;
 import com.google.common.annotations.GwtIncompatible;
@@ -33,6 +35,7 @@
 import java.util.Map;
 import java.util.Set;
 import java.util.function.ObjIntConsumer;
+import javax.annotation.CheckForNull;
 import org.checkerframework.checker.nullness.qual.Nullable;
 import org.checkerframework.dataflow.qual.Pure;
 import org.checkerframework.dataflow.qual.SideEffectFree;
@@ -48,7 +51,9 @@
  */
 @AnnotatedFor({"nullness"})
 @GwtCompatible(emulated = true)
-abstract class AbstractMapBasedMultiset<E> extends AbstractMultiset<E> implements Serializable {
+@ElementTypesAreNonnullByDefault
+abstract class AbstractMapBasedMultiset<E extends @Nullable Object> extends AbstractMultiset<E>
+    implements Serializable {
   // TODO(lowasser): consider overhauling this back to Map<E, Integer>
   private transient Map<E, Count> backingMap;
 
@@ -89,7 +94,7 @@ public Set<Multiset.Entry<E>> entrySet() {
   Iterator<E> elementIterator() {
     final Iterator<Map.Entry<E, Count>> backingEntries = backingMap.entrySet().iterator();
     return new Iterator<E>() {
-      Map.@Nullable Entry<E, Count> toRemove;
+      @CheckForNull Map.Entry<E, Count> toRemove;
 
       @Override
       public boolean hasNext() {
@@ -97,6 +102,7 @@ public boolean hasNext() {
       }
 
       @Override
+      @ParametricNullness
       public E next() {
         final Map.Entry<E, Count> mapEntry = backingEntries.next();
         toRemove = mapEntry;
@@ -105,7 +111,7 @@ public E next() {
 
       @Override
       public void remove() {
-        checkRemove(toRemove != null);
+        checkState(toRemove != null, "no calls to next() since the last call to remove()");
         size -= toRemove.getValue().getAndSet(0);
         backingEntries.remove();
         toRemove = null;
@@ -117,7 +123,7 @@ public void remove() {
   Iterator<Entry<E>> entryIterator() {
     final Iterator<Map.Entry<E, Count>> backingEntries = backingMap.entrySet().iterator();
     return new Iterator<Multiset.Entry<E>>() {
-      Map.@Nullable Entry<E, Count> toRemove;
+      @CheckForNull Map.Entry<E, Count> toRemove;
 
       @Override
       public boolean hasNext() {
@@ -130,6 +136,7 @@ public Multiset.Entry<E> next() {
         toRemove = mapEntry;
         return new Multisets.AbstractEntry<E>() {
           @Override
+          @ParametricNullness
           public E getElement() {
             return mapEntry.getKey();
           }
@@ -150,7 +157,7 @@ public int getCount() {
 
       @Override
       public void remove() {
-        checkRemove(toRemove != null);
+        checkState(toRemove != null, "no calls to next() since the last call to remove()");
         size -= toRemove.getValue().getAndSet(0);
         backingEntries.remove();
         toRemove = null;
@@ -198,7 +205,7 @@ public Iterator<E> iterator() {
    */
   private class MapBasedMultisetIterator implements Iterator<E> {
     final Iterator<Map.Entry<E, Count>> entryIterator;
-    Map.@Nullable Entry<E, Count> currentEntry;
+    @CheckForNull Map.Entry<E, Count> currentEntry;
     int occurrencesLeft;
     boolean canRemove;
 
@@ -212,6 +219,7 @@ public boolean hasNext() {
     }
 
     @Override
+    @ParametricNullness
     public E next() {
       if (occurrencesLeft == 0) {
         currentEntry = entryIterator.next();
@@ -219,13 +227,21 @@ public E next() {
       }
       occurrencesLeft--;
       canRemove = true;
-      return currentEntry.getKey();
+      /*
+       * requireNonNull is safe because occurrencesLeft starts at 0, forcing us to initialize
+       * currentEntry above. After that, we never clear it.
+       */
+      return requireNonNull(currentEntry).getKey();
     }
 
     @Override
     public void remove() {
       checkRemove(canRemove);
-      int frequency = currentEntry.getValue().get();
+      /*
+       * requireNonNull is safe because canRemove is set to true only after we initialize
+       * currentEntry (which we never subsequently clear).
+       */
+      int frequency = requireNonNull(currentEntry).getValue().get();
       if (frequency <= 0) {
         throw new ConcurrentModificationException();
       }
@@ -238,7 +254,7 @@ public void remove() {
   }
 
   @Override
-  public int count(@Nullable Object element) {
+  public int count(@CheckForNull Object element) {
     Count frequency = Maps.safeGet(backingMap, element);
     return (frequency == null) ? 0 : frequency.get();
   }
@@ -253,7 +269,7 @@ public int count(@Nullable Object element) {
    */
   @CanIgnoreReturnValue
   @Override
-  public int add(@Nullable E element, int occurrences) {
+  public int add(@ParametricNullness E element, int occurrences) {
     if (occurrences == 0) {
       return count(element);
     }
@@ -275,7 +291,7 @@ public int add(@Nullable E element, int occurrences) {
 
   @CanIgnoreReturnValue
   @Override
-  public int remove(@Nullable Object element, int occurrences) {
+  public int remove(@CheckForNull Object element, int occurrences) {
     if (occurrences == 0) {
       return count(element);
     }
@@ -303,7 +319,7 @@ public int remove(@Nullable Object element, int occurrences) {
   // Roughly a 33% performance improvement over AbstractMultiset.setCount().
   @CanIgnoreReturnValue
   @Override
-  public int setCount(@Nullable E element, int count) {
+  public int setCount(@ParametricNullness E element, int count) {
     checkNonnegative(count, "count");
 
     Count existingCounter;
@@ -324,7 +340,7 @@ public int setCount(@Nullable E element, int count) {
     return oldCount;
   }
 
-  private static int getAndSet(@Nullable Count i, int count) {
+  private static int getAndSet(@CheckForNull Count i, int count) {
     if (i == null) {
       return 0;
     }
diff --git a/guava/src/com/google/common/collect/AbstractMapEntry.java b/guava/src/com/google/common/collect/AbstractMapEntry.java
index 199ddf4e33d2..1a370dc1a648 100644
--- a/guava/src/com/google/common/collect/AbstractMapEntry.java
+++ b/guava/src/com/google/common/collect/AbstractMapEntry.java
@@ -19,6 +19,7 @@
 import com.google.common.annotations.GwtCompatible;
 import com.google.common.base.Objects;
 import java.util.Map.Entry;
+import javax.annotation.CheckForNull;
 import org.checkerframework.checker.nullness.qual.Nullable;
 import org.checkerframework.dataflow.qual.Pure;
 import org.checkerframework.framework.qual.AnnotatedFor;
@@ -31,24 +32,29 @@
  */
 @AnnotatedFor({"nullness"})
 @GwtCompatible
-abstract class AbstractMapEntry<K, V> implements Entry<K, V> {
+@ElementTypesAreNonnullByDefault
+abstract class AbstractMapEntry<K extends @Nullable Object, V extends @Nullable Object>
+    implements Entry<K, V> {
 
   @Pure
   @Override
+  @ParametricNullness
   public abstract K getKey();
 
   @Pure
   @Override
+  @ParametricNullness
   public abstract V getValue();
 
   @Override
-  public V setValue(V value) {
+  @ParametricNullness
+  public V setValue(@ParametricNullness V value) {
     throw new UnsupportedOperationException();
   }
 
   @Pure
   @Override
-  public boolean equals(@Nullable Object object) {
+  public boolean equals(@CheckForNull Object object) {
     if (object instanceof Entry) {
       Entry<?, ?> that = (Entry<?, ?>) object;
       return Objects.equal(this.getKey(), that.getKey())
diff --git a/guava/src/com/google/common/collect/AbstractMultimap.java b/guava/src/com/google/common/collect/AbstractMultimap.java
index e5b6753cb6e5..2f69ff380e07 100644
--- a/guava/src/com/google/common/collect/AbstractMultimap.java
+++ b/guava/src/com/google/common/collect/AbstractMultimap.java
@@ -30,6 +30,7 @@
 import java.util.Set;
 import java.util.Spliterator;
 import java.util.Spliterators;
+import javax.annotation.CheckForNull;
 import org.checkerframework.checker.nullness.qual.Nullable;
 import org.checkerframework.dataflow.qual.Pure;
 import org.checkerframework.dataflow.qual.SideEffectFree;
@@ -42,7 +43,9 @@
  */
 @AnnotatedFor({"nullness"})
 @GwtCompatible
-abstract class AbstractMultimap<K, V> implements Multimap<K, V> {
+@ElementTypesAreNonnullByDefault
+abstract class AbstractMultimap<K extends @Nullable Object, V extends @Nullable Object>
+    implements Multimap<K, V> {
   @Pure
   @Override
   public boolean isEmpty() {
@@ -51,7 +54,7 @@ public boolean isEmpty() {
 
   @Pure
   @Override
-  public boolean containsValue(@Nullable Object value) {
+  public boolean containsValue(@CheckForNull Object value) {
     for (Collection<V> collection : asMap().values()) {
       if (collection.contains(value)) {
         return true;
@@ -63,27 +66,27 @@ public boolean containsValue(@Nullable Object value) {
 
   @Pure
   @Override
-  public boolean containsEntry(@Nullable Object key, @Nullable Object value) {
+  public boolean containsEntry(@CheckForNull Object key, @CheckForNull Object value) {
     Collection<V> collection = asMap().get(key);
     return collection != null && collection.contains(value);
   }
 
   @CanIgnoreReturnValue
   @Override
-  public boolean remove(@Nullable Object key, @Nullable Object value) {
+  public boolean remove(@CheckForNull Object key, @CheckForNull Object value) {
     Collection<V> collection = asMap().get(key);
     return collection != null && collection.remove(value);
   }
 
   @CanIgnoreReturnValue
   @Override
-  public boolean put(@Nullable K key, @Nullable V value) {
+  public boolean put(@ParametricNullness K key, @ParametricNullness V value) {
     return get(key).add(value);
   }
 
   @CanIgnoreReturnValue
   @Override
-  public boolean putAll(@Nullable K key, Iterable<? extends V> values) {
+  public boolean putAll(@ParametricNullness K key, Iterable<? extends V> values) {
     checkNotNull(values);
     // make sure we only call values.iterator() once
     // and we only call get(key) if values is nonempty
@@ -108,14 +111,14 @@ public boolean putAll(Multimap<? extends K, ? extends V> multimap) {
 
   @CanIgnoreReturnValue
   @Override
-  public Collection<V> replaceValues(@Nullable K key, Iterable<? extends V> values) {
+  public Collection<V> replaceValues(@ParametricNullness K key, Iterable<? extends V> values) {
     checkNotNull(values);
     Collection<V> result = removeAll(key);
     putAll(key, values);
     return result;
   }
 
-  @LazyInit private transient @Nullable Collection<Entry<K, V>> entries;
+  @LazyInit @CheckForNull private transient Collection<Entry<K, V>> entries;
 
   @SideEffectFree
   @Override
@@ -154,7 +157,7 @@ public int hashCode() {
 
     @Pure
     @Override
-    public boolean equals(@Nullable Object obj) {
+    public boolean equals(@CheckForNull Object obj) {
       return Sets.equalsImpl(this, obj);
     }
   }
@@ -166,7 +169,7 @@ Spliterator<Entry<K, V>> entrySpliterator() {
         entryIterator(), size(), (this instanceof SetMultimap) ? Spliterator.DISTINCT : 0);
   }
 
-  @LazyInit private transient @Nullable Set<K> keySet;
+  @LazyInit @CheckForNull private transient Set<K> keySet;
 
   @SideEffectFree
   @Override
@@ -178,7 +181,7 @@ public Set<K> keySet() {
   @SideEffectFree
   abstract Set<K> createKeySet();
 
-  @LazyInit private transient @Nullable Multiset<K> keys;
+  @LazyInit @CheckForNull private transient Multiset<K> keys;
 
   @Override
   public Multiset<K> keys() {
@@ -188,7 +191,7 @@ public Multiset<K> keys() {
 
   abstract Multiset<K> createKeys();
 
-  @LazyInit private transient @Nullable Collection<V> values;
+  @LazyInit @CheckForNull private transient Collection<V> values;
 
   @SideEffectFree
   @Override
@@ -219,7 +222,7 @@ public int size() {
 
     @Pure
     @Override
-    public boolean contains(@Nullable Object o) {
+    public boolean contains(@CheckForNull Object o) {
       return AbstractMultimap.this.containsValue(o);
     }
 
@@ -237,7 +240,7 @@ Spliterator<V> valueSpliterator() {
     return Spliterators.spliterator(valueIterator(), size(), 0);
   }
 
-  @LazyInit private transient @Nullable Map<K, Collection<V>> asMap;
+  @LazyInit @CheckForNull private transient Map<K, Collection<V>> asMap;
 
   @Override
   public Map<K, Collection<V>> asMap() {
@@ -251,7 +254,7 @@ public Map<K, Collection<V>> asMap() {
 
   @Pure
   @Override
-  public boolean equals(@Nullable Object object) {
+  public boolean equals(@CheckForNull Object object) {
     return Multimaps.equalsImpl(this, object);
   }
 
diff --git a/guava/src/com/google/common/collect/AbstractMultiset.java b/guava/src/com/google/common/collect/AbstractMultiset.java
index 4f7a35c06c63..4d9559b04938 100644
--- a/guava/src/com/google/common/collect/AbstractMultiset.java
+++ b/guava/src/com/google/common/collect/AbstractMultiset.java
@@ -26,6 +26,7 @@
 import java.util.Collection;
 import java.util.Iterator;
 import java.util.Set;
+import javax.annotation.CheckForNull;
 import org.checkerframework.checker.nullness.qual.Nullable;
 import org.checkerframework.dataflow.qual.Pure;
 import org.checkerframework.dataflow.qual.SideEffectFree;
@@ -46,7 +47,9 @@
  */
 @AnnotatedFor({"nullness"})
 @GwtCompatible
-abstract class AbstractMultiset<E> extends AbstractCollection<E> implements Multiset<E> {
+@ElementTypesAreNonnullByDefault
+abstract class AbstractMultiset<E extends @Nullable Object> extends AbstractCollection<E>
+    implements Multiset<E> {
   // Query Operations
 
   @Pure
@@ -57,45 +60,45 @@ public boolean isEmpty() {
 
   @Pure
   @Override
-  public boolean contains(@Nullable Object element) {
+  public boolean contains(@CheckForNull Object element) {
     return count(element) > 0;
   }
 
   // Modification Operations
   @CanIgnoreReturnValue
   @Override
-  public final boolean add(@Nullable E element) {
+  public final boolean add(@ParametricNullness E element) {
     add(element, 1);
     return true;
   }
 
   @CanIgnoreReturnValue
   @Override
-  public int add(@Nullable E element, int occurrences) {
+  public int add(@ParametricNullness E element, int occurrences) {
     throw new UnsupportedOperationException();
   }
 
   @CanIgnoreReturnValue
   @Override
-  public final boolean remove(@Nullable Object element) {
+  public final boolean remove(@CheckForNull Object element) {
     return remove(element, 1) > 0;
   }
 
   @CanIgnoreReturnValue
   @Override
-  public int remove(@Nullable Object element, int occurrences) {
+  public int remove(@CheckForNull Object element, int occurrences) {
     throw new UnsupportedOperationException();
   }
 
   @CanIgnoreReturnValue
   @Override
-  public int setCount(@Nullable E element, int count) {
+  public int setCount(@ParametricNullness E element, int count) {
     return setCountImpl(this, element, count);
   }
 
   @CanIgnoreReturnValue
   @Override
-  public boolean setCount(@Nullable E element, int oldCount, int newCount) {
+  public boolean setCount(@ParametricNullness E element, int oldCount, int newCount) {
     return setCountImpl(this, element, oldCount, newCount);
   }
 
@@ -130,7 +133,7 @@ public final boolean retainAll(Collection<?> elementsToRetain) {
 
   // Views
 
-  @LazyInit private transient @Nullable Set<E> elementSet;
+  @LazyInit @CheckForNull private transient Set<E> elementSet;
 
   @SideEffectFree
   @Override
@@ -165,7 +168,7 @@ public Iterator<E> iterator() {
 
   abstract Iterator<E> elementIterator();
 
-  @LazyInit private transient @Nullable Set<Entry<E>> entrySet;
+  @LazyInit @CheckForNull private transient Set<Entry<E>> entrySet;
 
   @SideEffectFree
   @Override
@@ -213,7 +216,7 @@ Set<Entry<E>> createEntrySet() {
    */
   @Pure
   @Override
-  public final boolean equals(@Nullable Object object) {
+  public final boolean equals(@CheckForNull Object object) {
     return Multisets.equalsImpl(this, object);
   }
 
diff --git a/guava/src/com/google/common/collect/AbstractNavigableMap.java b/guava/src/com/google/common/collect/AbstractNavigableMap.java
index b0200d7245b0..47048d06ac49 100644
--- a/guava/src/com/google/common/collect/AbstractNavigableMap.java
+++ b/guava/src/com/google/common/collect/AbstractNavigableMap.java
@@ -24,6 +24,7 @@
 import java.util.NoSuchElementException;
 import java.util.Set;
 import java.util.SortedMap;
+import javax.annotation.CheckForNull;
 import org.checkerframework.checker.nullness.qual.Nullable;
 
 /**
@@ -32,33 +33,40 @@
  * @author Louis Wasserman
  */
 @GwtIncompatible
-abstract class AbstractNavigableMap<K, V> extends IteratorBasedAbstractMap<K, V>
-    implements NavigableMap<K, V> {
+@ElementTypesAreNonnullByDefault
+abstract class AbstractNavigableMap<K extends @Nullable Object, V extends @Nullable Object>
+    extends IteratorBasedAbstractMap<K, V> implements NavigableMap<K, V> {
 
   @Override
-  public abstract @Nullable V get(@Nullable Object key);
+  @CheckForNull
+  public abstract V get(@CheckForNull Object key);
 
   @Override
-  public @Nullable Entry<K, V> firstEntry() {
+  @CheckForNull
+  public Entry<K, V> firstEntry() {
     return Iterators.getNext(entryIterator(), null);
   }
 
   @Override
-  public @Nullable Entry<K, V> lastEntry() {
+  @CheckForNull
+  public Entry<K, V> lastEntry() {
     return Iterators.getNext(descendingEntryIterator(), null);
   }
 
   @Override
-  public @Nullable Entry<K, V> pollFirstEntry() {
+  @CheckForNull
+  public Entry<K, V> pollFirstEntry() {
     return Iterators.pollNext(entryIterator());
   }
 
   @Override
-  public @Nullable Entry<K, V> pollLastEntry() {
+  @CheckForNull
+  public Entry<K, V> pollLastEntry() {
     return Iterators.pollNext(descendingEntryIterator());
   }
 
   @Override
+  @ParametricNullness
   public K firstKey() {
     Entry<K, V> entry = firstEntry();
     if (entry == null) {
@@ -69,6 +77,7 @@ public K firstKey() {
   }
 
   @Override
+  @ParametricNullness
   public K lastKey() {
     Entry<K, V> entry = lastEntry();
     if (entry == null) {
@@ -79,59 +88,67 @@ public K lastKey() {
   }
 
   @Override
-  public @Nullable Entry<K, V> lowerEntry(K key) {
+  @CheckForNull
+  public Entry<K, V> lowerEntry(@ParametricNullness K key) {
     return headMap(key, false).lastEntry();
   }
 
   @Override
-  public @Nullable Entry<K, V> floorEntry(K key) {
+  @CheckForNull
+  public Entry<K, V> floorEntry(@ParametricNullness K key) {
     return headMap(key, true).lastEntry();
   }
 
   @Override
-  public @Nullable Entry<K, V> ceilingEntry(K key) {
+  @CheckForNull
+  public Entry<K, V> ceilingEntry(@ParametricNullness K key) {
     return tailMap(key, true).firstEntry();
   }
 
   @Override
-  public @Nullable Entry<K, V> higherEntry(K key) {
+  @CheckForNull
+  public Entry<K, V> higherEntry(@ParametricNullness K key) {
     return tailMap(key, false).firstEntry();
   }
 
   @Override
-  public K lowerKey(K key) {
+  @CheckForNull
+  public K lowerKey(@ParametricNullness K key) {
     return Maps.keyOrNull(lowerEntry(key));
   }
 
   @Override
-  public K floorKey(K key) {
+  @CheckForNull
+  public K floorKey(@ParametricNullness K key) {
     return Maps.keyOrNull(floorEntry(key));
   }
 
   @Override
-  public K ceilingKey(K key) {
+  @CheckForNull
+  public K ceilingKey(@ParametricNullness K key) {
     return Maps.keyOrNull(ceilingEntry(key));
   }
 
   @Override
-  public K higherKey(K key) {
+  @CheckForNull
+  public K higherKey(@ParametricNullness K key) {
     return Maps.keyOrNull(higherEntry(key));
   }
 
   abstract Iterator<Entry<K, V>> descendingEntryIterator();
 
   @Override
-  public SortedMap<K, V> subMap(K fromKey, K toKey) {
+  public SortedMap<K, V> subMap(@ParametricNullness K fromKey, @ParametricNullness K toKey) {
     return subMap(fromKey, true, toKey, false);
   }
 
   @Override
-  public SortedMap<K, V> headMap(K toKey) {
+  public SortedMap<K, V> headMap(@ParametricNullness K toKey) {
     return headMap(toKey, false);
   }
 
   @Override
-  public SortedMap<K, V> tailMap(K fromKey) {
+  public SortedMap<K, V> tailMap(@ParametricNullness K fromKey) {
     return tailMap(fromKey, true);
   }
 
diff --git a/guava/src/com/google/common/collect/AbstractRangeSet.java b/guava/src/com/google/common/collect/AbstractRangeSet.java
index 1c454cdfc318..d112a11f1814 100644
--- a/guava/src/com/google/common/collect/AbstractRangeSet.java
+++ b/guava/src/com/google/common/collect/AbstractRangeSet.java
@@ -15,7 +15,7 @@
 package com.google.common.collect;
 
 import com.google.common.annotations.GwtIncompatible;
-import org.checkerframework.checker.nullness.qual.Nullable;
+import javax.annotation.CheckForNull;
 
 /**
  * A skeletal implementation of {@code RangeSet}.
@@ -23,6 +23,7 @@
  * @author Louis Wasserman
  */
 @GwtIncompatible
+@ElementTypesAreNonnullByDefault
 abstract class AbstractRangeSet<C extends Comparable> implements RangeSet<C> {
   AbstractRangeSet() {}
 
@@ -32,6 +33,7 @@ public boolean contains(C value) {
   }
 
   @Override
+  @CheckForNull
   public abstract Range<C> rangeContaining(C value);
 
   @Override
@@ -78,7 +80,7 @@ public boolean intersects(Range<C> otherRange) {
   public abstract boolean encloses(Range<C> otherRange);
 
   @Override
-  public boolean equals(@Nullable Object obj) {
+  public boolean equals(@CheckForNull Object obj) {
     if (obj == this) {
       return true;
     } else if (obj instanceof RangeSet) {
diff --git a/guava/src/com/google/common/collect/AbstractSequentialIterator.java b/guava/src/com/google/common/collect/AbstractSequentialIterator.java
index 37540c2f00fb..172fe356cb78 100644
--- a/guava/src/com/google/common/collect/AbstractSequentialIterator.java
+++ b/guava/src/com/google/common/collect/AbstractSequentialIterator.java
@@ -18,7 +18,7 @@
 
 import com.google.common.annotations.GwtCompatible;
 import java.util.NoSuchElementException;
-import org.checkerframework.checker.nullness.qual.Nullable;
+import javax.annotation.CheckForNull;
 
 /**
  * This class provides a skeletal implementation of the {@code Iterator} interface for sequences
@@ -40,14 +40,15 @@
  * @since 12.0 (in Guava as {@code AbstractLinkedIterator} since 8.0)
  */
 @GwtCompatible
+@ElementTypesAreNonnullByDefault
 public abstract class AbstractSequentialIterator<T> extends UnmodifiableIterator<T> {
-  private @Nullable T nextOrNull;
+  @CheckForNull private T nextOrNull;
 
   /**
    * Creates a new iterator with the given first element, or, if {@code firstOrNull} is null,
    * creates a new empty iterator.
    */
-  protected AbstractSequentialIterator(@Nullable T firstOrNull) {
+  protected AbstractSequentialIterator(@CheckForNull T firstOrNull) {
     this.nextOrNull = firstOrNull;
   }
 
@@ -56,7 +57,8 @@ protected AbstractSequentialIterator(@Nullable T firstOrNull) {
    * remain. This method is invoked during each call to {@link #next()} in order to compute the
    * result of a <i>future</i> call to {@code next()}.
    */
-  protected abstract @Nullable T computeNext(T previous);
+  @CheckForNull
+  protected abstract T computeNext(T previous);
 
   @Override
   public final boolean hasNext() {
@@ -65,13 +67,11 @@ public final boolean hasNext() {
 
   @Override
   public final T next() {
-    if (!hasNext()) {
+    if (nextOrNull == null) {
       throw new NoSuchElementException();
     }
-    try {
-      return nextOrNull;
-    } finally {
-      nextOrNull = computeNext(nextOrNull);
-    }
+    T oldNext = nextOrNull;
+    nextOrNull = computeNext(oldNext);
+    return oldNext;
   }
 }
diff --git a/guava/src/com/google/common/collect/AbstractSetMultimap.java b/guava/src/com/google/common/collect/AbstractSetMultimap.java
index ab7a466a164d..00b2603d9e5b 100644
--- a/guava/src/com/google/common/collect/AbstractSetMultimap.java
+++ b/guava/src/com/google/common/collect/AbstractSetMultimap.java
@@ -23,6 +23,7 @@
 import java.util.Map;
 import java.util.Map.Entry;
 import java.util.Set;
+import javax.annotation.CheckForNull;
 import org.checkerframework.checker.nullness.qual.Nullable;
 import org.checkerframework.dataflow.qual.Pure;
 import org.checkerframework.dataflow.qual.SideEffectFree;
@@ -37,8 +38,9 @@
  */
 @AnnotatedFor({"nullness"})
 @GwtCompatible
-abstract class AbstractSetMultimap<K, V> extends AbstractMapBasedMultimap<K, V>
-    implements SetMultimap<K, V> {
+@ElementTypesAreNonnullByDefault
+abstract class AbstractSetMultimap<K extends @Nullable Object, V extends @Nullable Object>
+    extends AbstractMapBasedMultimap<K, V> implements SetMultimap<K, V> {
   /**
    * Creates a new multimap that uses the provided map.
    *
@@ -57,12 +59,13 @@ Set<V> createUnmodifiableEmptyCollection() {
   }
 
   @Override
-  <E> Collection<E> unmodifiableCollectionSubclass(Collection<E> collection) {
+  <E extends @Nullable Object> Collection<E> unmodifiableCollectionSubclass(
+      Collection<E> collection) {
     return Collections.unmodifiableSet((Set<E>) collection);
   }
 
   @Override
-  Collection<V> wrapCollection(K key, Collection<V> collection) {
+  Collection<V> wrapCollection(@ParametricNullness K key, Collection<V> collection) {
     return new WrappedSet(key, (Set<V>) collection);
   }
 
@@ -75,7 +78,7 @@ Collection<V> wrapCollection(K key, Collection<V> collection) {
    * {@link Set}, instead of the {@link Collection} specified in the {@link Multimap} interface.
    */
   @Override
-  public Set<V> get(@Nullable K key) {
+  public Set<V> get(@ParametricNullness K key) {
     return (Set<V>) super.get(key);
   }
 
@@ -99,7 +102,7 @@ public Set<Entry<K, V>> entries() {
    */
   @CanIgnoreReturnValue
   @Override
-  public Set<V> removeAll(@Nullable Object key) {
+  public Set<V> removeAll(@CheckForNull Object key) {
     return (Set<V>) super.removeAll(key);
   }
 
@@ -113,7 +116,7 @@ public Set<V> removeAll(@Nullable Object key) {
    */
   @CanIgnoreReturnValue
   @Override
-  public Set<V> replaceValues(@Nullable K key, Iterable<? extends V> values) {
+  public Set<V> replaceValues(@ParametricNullness K key, Iterable<? extends V> values) {
     return (Set<V>) super.replaceValues(key, values);
   }
 
@@ -138,7 +141,7 @@ public Map<K, Collection<V>> asMap() {
    */
   @CanIgnoreReturnValue
   @Override
-  public boolean put(@Nullable K key, @Nullable V value) {
+  public boolean put(@ParametricNullness K key, @ParametricNullness V value) {
     return super.put(key, value);
   }
 
@@ -150,7 +153,7 @@ public boolean put(@Nullable K key, @Nullable V value) {
    */
   @Pure
   @Override
-  public boolean equals(@Nullable Object object) {
+  public boolean equals(@CheckForNull Object object) {
     return super.equals(object);
   }
 
diff --git a/guava/src/com/google/common/collect/AbstractSortedKeySortedSetMultimap.java b/guava/src/com/google/common/collect/AbstractSortedKeySortedSetMultimap.java
index 0ee6edb1e090..676936f0578e 100644
--- a/guava/src/com/google/common/collect/AbstractSortedKeySortedSetMultimap.java
+++ b/guava/src/com/google/common/collect/AbstractSortedKeySortedSetMultimap.java
@@ -21,6 +21,7 @@
 import java.util.Set;
 import java.util.SortedMap;
 import java.util.SortedSet;
+import org.checkerframework.checker.nullness.qual.Nullable;
 
 /**
  * Basic implementation of a {@link SortedSetMultimap} with a sorted key set.
@@ -31,7 +32,10 @@
  * @author Louis Wasserman
  */
 @GwtCompatible
-abstract class AbstractSortedKeySortedSetMultimap<K, V> extends AbstractSortedSetMultimap<K, V> {
+@ElementTypesAreNonnullByDefault
+abstract class AbstractSortedKeySortedSetMultimap<
+        K extends @Nullable Object, V extends @Nullable Object>
+    extends AbstractSortedSetMultimap<K, V> {
 
   AbstractSortedKeySortedSetMultimap(SortedMap<K, Collection<V>> map) {
     super(map);
diff --git a/guava/src/com/google/common/collect/AbstractSortedMultiset.java b/guava/src/com/google/common/collect/AbstractSortedMultiset.java
index 67d629a40fec..621e8f98a5e2 100644
--- a/guava/src/com/google/common/collect/AbstractSortedMultiset.java
+++ b/guava/src/com/google/common/collect/AbstractSortedMultiset.java
@@ -21,6 +21,7 @@
 import java.util.Comparator;
 import java.util.Iterator;
 import java.util.NavigableSet;
+import javax.annotation.CheckForNull;
 import org.checkerframework.checker.nullness.qual.Nullable;
 
 /**
@@ -33,7 +34,9 @@
  * @author Louis Wasserman
  */
 @GwtCompatible(emulated = true)
-abstract class AbstractSortedMultiset<E> extends AbstractMultiset<E> implements SortedMultiset<E> {
+@ElementTypesAreNonnullByDefault
+abstract class AbstractSortedMultiset<E extends @Nullable Object> extends AbstractMultiset<E>
+    implements SortedMultiset<E> {
   @GwtTransient final Comparator<? super E> comparator;
 
   // needed for serialization
@@ -53,7 +56,7 @@ public NavigableSet<E> elementSet() {
 
   @Override
   NavigableSet<E> createElementSet() {
-    return new SortedMultisets.NavigableElementSet<E>(this);
+    return new SortedMultisets.NavigableElementSet<>(this);
   }
 
   @Override
@@ -62,18 +65,21 @@ public Comparator<? super E> comparator() {
   }
 
   @Override
+  @CheckForNull
   public Entry<E> firstEntry() {
     Iterator<Entry<E>> entryIterator = entryIterator();
     return entryIterator.hasNext() ? entryIterator.next() : null;
   }
 
   @Override
+  @CheckForNull
   public Entry<E> lastEntry() {
     Iterator<Entry<E>> entryIterator = descendingEntryIterator();
     return entryIterator.hasNext() ? entryIterator.next() : null;
   }
 
   @Override
+  @CheckForNull
   public Entry<E> pollFirstEntry() {
     Iterator<Entry<E>> entryIterator = entryIterator();
     if (entryIterator.hasNext()) {
@@ -86,6 +92,7 @@ public Entry<E> pollFirstEntry() {
   }
 
   @Override
+  @CheckForNull
   public Entry<E> pollLastEntry() {
     Iterator<Entry<E>> entryIterator = descendingEntryIterator();
     if (entryIterator.hasNext()) {
@@ -99,9 +106,9 @@ public Entry<E> pollLastEntry() {
 
   @Override
   public SortedMultiset<E> subMultiset(
-      @Nullable E fromElement,
+      @ParametricNullness E fromElement,
       BoundType fromBoundType,
-      @Nullable E toElement,
+      @ParametricNullness E toElement,
       BoundType toBoundType) {
     // These are checked elsewhere, but NullPointerTester wants them checked eagerly.
     checkNotNull(fromBoundType);
@@ -115,7 +122,7 @@ Iterator<E> descendingIterator() {
     return Multisets.iteratorImpl(descendingMultiset());
   }
 
-  private transient @Nullable SortedMultiset<E> descendingMultiset;
+  @CheckForNull private transient SortedMultiset<E> descendingMultiset;
 
   @Override
   public SortedMultiset<E> descendingMultiset() {
diff --git a/guava/src/com/google/common/collect/AbstractSortedSetMultimap.java b/guava/src/com/google/common/collect/AbstractSortedSetMultimap.java
index d04c09830b17..9dc81b1b8057 100644
--- a/guava/src/com/google/common/collect/AbstractSortedSetMultimap.java
+++ b/guava/src/com/google/common/collect/AbstractSortedSetMultimap.java
@@ -23,6 +23,7 @@
 import java.util.Map;
 import java.util.NavigableSet;
 import java.util.SortedSet;
+import javax.annotation.CheckForNull;
 import org.checkerframework.checker.nullness.qual.Nullable;
 import org.checkerframework.dataflow.qual.SideEffectFree;
 import org.checkerframework.framework.qual.AnnotatedFor;
@@ -36,8 +37,9 @@
  */
 @AnnotatedFor({"nullness"})
 @GwtCompatible
-abstract class AbstractSortedSetMultimap<K, V> extends AbstractSetMultimap<K, V>
-    implements SortedSetMultimap<K, V> {
+@ElementTypesAreNonnullByDefault
+abstract class AbstractSortedSetMultimap<K extends @Nullable Object, V extends @Nullable Object>
+    extends AbstractSetMultimap<K, V> implements SortedSetMultimap<K, V> {
   /**
    * Creates a new multimap that uses the provided map.
    *
@@ -56,7 +58,8 @@ SortedSet<V> createUnmodifiableEmptyCollection() {
   }
 
   @Override
-  <E> SortedSet<E> unmodifiableCollectionSubclass(Collection<E> collection) {
+  <E extends @Nullable Object> SortedSet<E> unmodifiableCollectionSubclass(
+      Collection<E> collection) {
     if (collection instanceof NavigableSet) {
       return Sets.unmodifiableNavigableSet((NavigableSet<E>) collection);
     } else {
@@ -65,7 +68,7 @@ <E> SortedSet<E> unmodifiableCollectionSubclass(Collection<E> collection) {
   }
 
   @Override
-  Collection<V> wrapCollection(K key, Collection<V> collection) {
+  Collection<V> wrapCollection(@ParametricNullness K key, Collection<V> collection) {
     if (collection instanceof NavigableSet) {
       return new WrappedNavigableSet(key, (NavigableSet<V>) collection, null);
     } else {
@@ -86,7 +89,7 @@ Collection<V> wrapCollection(K key, Collection<V> collection) {
    * Multimap} interface.
    */
   @Override
-  public SortedSet<V> get(@Nullable K key) {
+  public SortedSet<V> get(@ParametricNullness K key) {
     return (SortedSet<V>) super.get(key);
   }
 
@@ -99,7 +102,7 @@ public SortedSet<V> get(@Nullable K key) {
    */
   @CanIgnoreReturnValue
   @Override
-  public SortedSet<V> removeAll(@Nullable Object key) {
+  public SortedSet<V> removeAll(@CheckForNull Object key) {
     return (SortedSet<V>) super.removeAll(key);
   }
 
@@ -115,7 +118,7 @@ public SortedSet<V> removeAll(@Nullable Object key) {
    */
   @CanIgnoreReturnValue
   @Override
-  public SortedSet<V> replaceValues(@Nullable K key, Iterable<? extends V> values) {
+  public SortedSet<V> replaceValues(@ParametricNullness K key, Iterable<? extends V> values) {
     return (SortedSet<V>) super.replaceValues(key, values);
   }
 
diff --git a/guava/src/com/google/common/collect/AbstractTable.java b/guava/src/com/google/common/collect/AbstractTable.java
index 823570d787af..99a121590654 100644
--- a/guava/src/com/google/common/collect/AbstractTable.java
+++ b/guava/src/com/google/common/collect/AbstractTable.java
@@ -25,6 +25,7 @@
 import java.util.Map;
 import java.util.Set;
 import java.util.Spliterator;
+import javax.annotation.CheckForNull;
 import org.checkerframework.checker.nullness.qual.Nullable;
 
 /**
@@ -33,15 +34,18 @@
  * @author Louis Wasserman
  */
 @GwtCompatible
-abstract class AbstractTable<R, C, V> implements Table<R, C, V> {
+@ElementTypesAreNonnullByDefault
+abstract class AbstractTable<
+        R extends @Nullable Object, C extends @Nullable Object, V extends @Nullable Object>
+    implements Table<R, C, V> {
 
   @Override
-  public boolean containsRow(@Nullable Object rowKey) {
+  public boolean containsRow(@CheckForNull Object rowKey) {
     return Maps.safeContainsKey(rowMap(), rowKey);
   }
 
   @Override
-  public boolean containsColumn(@Nullable Object columnKey) {
+  public boolean containsColumn(@CheckForNull Object columnKey) {
     return Maps.safeContainsKey(columnMap(), columnKey);
   }
 
@@ -56,7 +60,7 @@ public Set<C> columnKeySet() {
   }
 
   @Override
-  public boolean containsValue(@Nullable Object value) {
+  public boolean containsValue(@CheckForNull Object value) {
     for (Map<C, V> row : rowMap().values()) {
       if (row.containsValue(value)) {
         return true;
@@ -66,13 +70,14 @@ public boolean containsValue(@Nullable Object value) {
   }
 
   @Override
-  public boolean contains(@Nullable Object rowKey, @Nullable Object columnKey) {
+  public boolean contains(@CheckForNull Object rowKey, @CheckForNull Object columnKey) {
     Map<C, V> row = Maps.safeGet(rowMap(), rowKey);
     return row != null && Maps.safeContainsKey(row, columnKey);
   }
 
   @Override
-  public V get(@Nullable Object rowKey, @Nullable Object columnKey) {
+  @CheckForNull
+  public V get(@CheckForNull Object rowKey, @CheckForNull Object columnKey) {
     Map<C, V> row = Maps.safeGet(rowMap(), rowKey);
     return (row == null) ? null : Maps.safeGet(row, columnKey);
   }
@@ -89,14 +94,17 @@ public void clear() {
 
   @CanIgnoreReturnValue
   @Override
-  public V remove(@Nullable Object rowKey, @Nullable Object columnKey) {
+  @CheckForNull
+  public V remove(@CheckForNull Object rowKey, @CheckForNull Object columnKey) {
     Map<C, V> row = Maps.safeGet(rowMap(), rowKey);
     return (row == null) ? null : Maps.safeRemove(row, columnKey);
   }
 
   @CanIgnoreReturnValue
   @Override
-  public V put(R rowKey, C columnKey, V value) {
+  @CheckForNull
+  public V put(
+      @ParametricNullness R rowKey, @ParametricNullness C columnKey, @ParametricNullness V value) {
     return row(rowKey).put(columnKey, value);
   }
 
@@ -107,7 +115,7 @@ public void putAll(Table<? extends R, ? extends C, ? extends V> table) {
     }
   }
 
-  @LazyInit private transient @Nullable Set<Cell<R, C, V>> cellSet;
+  @LazyInit @CheckForNull private transient Set<Cell<R, C, V>> cellSet;
 
   @Override
   public Set<Cell<R, C, V>> cellSet() {
@@ -126,7 +134,7 @@ Set<Cell<R, C, V>> createCellSet() {
   @WeakOuter
   class CellSet extends AbstractSet<Cell<R, C, V>> {
     @Override
-    public boolean contains(Object o) {
+    public boolean contains(@CheckForNull Object o) {
       if (o instanceof Cell) {
         Cell<?, ?, ?> cell = (Cell<?, ?, ?>) o;
         Map<C, V> row = Maps.safeGet(rowMap(), cell.getRowKey());
@@ -138,7 +146,7 @@ public boolean contains(Object o) {
     }
 
     @Override
-    public boolean remove(@Nullable Object o) {
+    public boolean remove(@CheckForNull Object o) {
       if (o instanceof Cell) {
         Cell<?, ?, ?> cell = (Cell<?, ?, ?>) o;
         Map<C, V> row = Maps.safeGet(rowMap(), cell.getRowKey());
@@ -170,7 +178,7 @@ public int size() {
     }
   }
 
-  @LazyInit private transient @Nullable Collection<V> values;
+  @LazyInit @CheckForNull private transient Collection<V> values;
 
   @Override
   public Collection<V> values() {
@@ -185,6 +193,7 @@ Collection<V> createValues() {
   Iterator<V> valuesIterator() {
     return new TransformedIterator<Cell<R, C, V>, V>(cellSet().iterator()) {
       @Override
+      @ParametricNullness
       V transform(Cell<R, C, V> cell) {
         return cell.getValue();
       }
@@ -208,7 +217,7 @@ public Spliterator<V> spliterator() {
     }
 
     @Override
-    public boolean contains(Object o) {
+    public boolean contains(@CheckForNull Object o) {
       return containsValue(o);
     }
 
@@ -224,7 +233,7 @@ public int size() {
   }
 
   @Override
-  public boolean equals(@Nullable Object obj) {
+  public boolean equals(@CheckForNull Object obj) {
     return Tables.equalsImpl(this, obj);
   }
 
diff --git a/guava/src/com/google/common/collect/AllEqualOrdering.java b/guava/src/com/google/common/collect/AllEqualOrdering.java
index 357b1fcd2c0f..f6ca6faff797 100644
--- a/guava/src/com/google/common/collect/AllEqualOrdering.java
+++ b/guava/src/com/google/common/collect/AllEqualOrdering.java
@@ -19,6 +19,7 @@
 import com.google.common.annotations.GwtCompatible;
 import java.io.Serializable;
 import java.util.List;
+import javax.annotation.CheckForNull;
 import org.checkerframework.checker.nullness.qual.Nullable;
 
 /**
@@ -27,27 +28,29 @@
  * @author Emily Soldal
  */
 @GwtCompatible(serializable = true)
-final class AllEqualOrdering extends Ordering<Object> implements Serializable {
+@ElementTypesAreNonnullByDefault
+final class AllEqualOrdering extends Ordering<@Nullable Object> implements Serializable {
   static final AllEqualOrdering INSTANCE = new AllEqualOrdering();
 
   @Override
-  public int compare(@Nullable Object left, @Nullable Object right) {
+  public int compare(@CheckForNull Object left, @CheckForNull Object right) {
     return 0;
   }
 
   @Override
-  public <E> List<E> sortedCopy(Iterable<E> iterable) {
+  public <E extends @Nullable Object> List<E> sortedCopy(Iterable<E> iterable) {
     return Lists.newArrayList(iterable);
   }
 
   @Override
-  public <E> ImmutableList<E> immutableSortedCopy(Iterable<E> iterable) {
+  @SuppressWarnings("nullness") // unsafe: see supertype
+  public <E extends @Nullable Object> ImmutableList<E> immutableSortedCopy(Iterable<E> iterable) {
     return ImmutableList.copyOf(iterable);
   }
 
   @SuppressWarnings("unchecked")
   @Override
-  public <S> Ordering<S> reverse() {
+  public <S extends @Nullable Object> Ordering<S> reverse() {
     return (Ordering<S>) this;
   }
 
diff --git a/guava/src/com/google/common/collect/ArrayListMultimap.java b/guava/src/com/google/common/collect/ArrayListMultimap.java
index c77e60228429..67e33bbabaef 100644
--- a/guava/src/com/google/common/collect/ArrayListMultimap.java
+++ b/guava/src/com/google/common/collect/ArrayListMultimap.java
@@ -55,15 +55,15 @@
  * with a call to {@link Multimaps#synchronizedListMultimap}.
  *
  * <p>See the Guava User Guide article on <a href=
- * "https://github.com/google/guava/wiki/NewCollectionTypesExplained#multimap"> {@code
- * Multimap}</a>.
+ * "https://github.com/google/guava/wiki/NewCollectionTypesExplained#multimap">{@code Multimap}</a>.
  *
  * @author Jared Levy
  * @since 2.0
  */
 @AnnotatedFor({"nullness"})
 @GwtCompatible(serializable = true, emulated = true)
-public final class ArrayListMultimap<K, V>
+@ElementTypesAreNonnullByDefault
+public final class ArrayListMultimap<K extends @Nullable Object, V extends @Nullable Object>
     extends ArrayListMultimapGwtSerializationDependencies<K, V> {
   // Default from ArrayList
   private static final int DEFAULT_VALUES_PER_KEY = 3;
@@ -76,7 +76,8 @@ public final class ArrayListMultimap<K, V>
    * <p>This method will soon be deprecated in favor of {@code
    * MultimapBuilder.hashKeys().arrayListValues().build()}.
    */
-  public static <K, V> ArrayListMultimap<K, V> create() {
+  public static <K extends @Nullable Object, V extends @Nullable Object>
+      ArrayListMultimap<K, V> create() {
     return new ArrayListMultimap<>();
   }
 
@@ -92,7 +93,8 @@ public static <K, V> ArrayListMultimap<K, V> create() {
    * @throws IllegalArgumentException if {@code expectedKeys} or {@code expectedValuesPerKey} is
    *     negative
    */
-  public static <K, V> ArrayListMultimap<K, V> create(int expectedKeys, int expectedValuesPerKey) {
+  public static <K extends @Nullable Object, V extends @Nullable Object>
+      ArrayListMultimap<K, V> create(int expectedKeys, int expectedValuesPerKey) {
     return new ArrayListMultimap<>(expectedKeys, expectedValuesPerKey);
   }
 
@@ -104,7 +106,8 @@ public static <K, V> ArrayListMultimap<K, V> create(int expectedKeys, int expect
    *
    * @param multimap the multimap whose contents are copied to this multimap
    */
-  public static <K, V> ArrayListMultimap<K, V> create(Multimap<? extends K, ? extends V> multimap) {
+  public static <K extends @Nullable Object, V extends @Nullable Object>
+      ArrayListMultimap<K, V> create(Multimap<? extends K, ? extends V> multimap) {
     return new ArrayListMultimap<>(multimap);
   }
 
diff --git a/guava/src/com/google/common/collect/ArrayTable.java b/guava/src/com/google/common/collect/ArrayTable.java
index fa22fe4e08bd..1fce76244954 100644
--- a/guava/src/com/google/common/collect/ArrayTable.java
+++ b/guava/src/com/google/common/collect/ArrayTable.java
@@ -19,6 +19,7 @@
 import static com.google.common.base.Preconditions.checkArgument;
 import static com.google.common.base.Preconditions.checkElementIndex;
 import static com.google.common.base.Preconditions.checkNotNull;
+import static java.util.Collections.emptyMap;
 
 import com.google.common.annotations.Beta;
 import com.google.common.annotations.GwtCompatible;
@@ -36,11 +37,22 @@
 import java.util.Map;
 import java.util.Set;
 import java.util.Spliterator;
+import javax.annotation.CheckForNull;
 import org.checkerframework.checker.nullness.qual.Nullable;
 
 /**
  * Fixed-size {@link Table} implementation backed by a two-dimensional array.
  *
+ * <p><b>Warning:</b> {@code ArrayTable} is rarely the {@link Table} implementation you want. First,
+ * it requires that the complete universe of rows and columns be specified at construction time.
+ * Second, it is always backed by an array large enough to hold a value for every possible
+ * combination of row and column keys. (This is rarely optimal unless the table is extremely dense.)
+ * Finally, every possible combination of row and column keys is always considered to have a value
+ * associated with it: It is not possible to "remove" a value, only to replace it with {@code null},
+ * which will still appear when iterating over the table's contents in a foreach loop or a call to a
+ * null-hostile method like {@link ImmutableTable#copyOf}. For alternatives, please see <a
+ * href="https://github.com/google/guava/wiki/NewCollectionTypesExplained#table">the wiki</a>.
+ *
  * <p>The allowed row and column keys must be supplied when the table is created. The table always
  * contains a mapping for every row key / column pair. The value corresponding to a given row and
  * column is null unless another value is provided.
@@ -72,14 +84,16 @@
  * thread that reads from another.
  *
  * <p>See the Guava User Guide article on <a href=
- * "https://github.com/google/guava/wiki/NewCollectionTypesExplained#table"> {@code Table}</a>.
+ * "https://github.com/google/guava/wiki/NewCollectionTypesExplained#table">{@code Table}</a>.
  *
  * @author Jared Levy
  * @since 10.0
  */
 @Beta
 @GwtCompatible(emulated = true)
-public final class ArrayTable<R, C, V> extends AbstractTable<R, C, V> implements Serializable {
+@ElementTypesAreNonnullByDefault
+public final class ArrayTable<R, C, V> extends AbstractTable<R, C, @Nullable V>
+    implements Serializable {
 
   /**
    * Creates an {@code ArrayTable} filled with {@code null}.
@@ -119,8 +133,8 @@ public static <R, C, V> ArrayTable<R, C, V> create(
    *
    * @throws NullPointerException if {@code table} has a null key
    */
-  public static <R, C, V> ArrayTable<R, C, V> create(Table<R, C, V> table) {
-    return (table instanceof ArrayTable<?, ?, ?>)
+  public static <R, C, V> ArrayTable<R, C, V> create(Table<R, C, ? extends @Nullable V> table) {
+    return (table instanceof ArrayTable)
         ? new ArrayTable<R, C, V>((ArrayTable<R, C, V>) table)
         : new ArrayTable<R, C, V>(table);
   }
@@ -131,7 +145,7 @@ public static <R, C, V> ArrayTable<R, C, V> create(Table<R, C, V> table) {
   // TODO(jlevy): Add getters returning rowKeyToIndex and columnKeyToIndex?
   private final ImmutableMap<R, Integer> rowKeyToIndex;
   private final ImmutableMap<C, Integer> columnKeyToIndex;
-  private final V[][] array;
+  private final @Nullable V[][] array;
 
   private ArrayTable(Iterable<? extends R> rowKeys, Iterable<? extends C> columnKeys) {
     this.rowList = ImmutableList.copyOf(rowKeys);
@@ -148,13 +162,14 @@ private ArrayTable(Iterable<? extends R> rowKeys, Iterable<? extends C> columnKe
     columnKeyToIndex = Maps.indexMap(columnList);
 
     @SuppressWarnings("unchecked")
-    V[][] tmpArray = (V[][]) new Object[rowList.size()][columnList.size()];
+    @Nullable
+    V[][] tmpArray = (@Nullable V[][]) new Object[rowList.size()][columnList.size()];
     array = tmpArray;
     // Necessary because in GWT the arrays are initialized with "undefined" instead of null.
     eraseAll();
   }
 
-  private ArrayTable(Table<R, C, V> table) {
+  private ArrayTable(Table<R, C, ? extends @Nullable V> table) {
     this(table.rowKeySet(), table.columnKeySet());
     putAll(table);
   }
@@ -165,14 +180,16 @@ private ArrayTable(ArrayTable<R, C, V> table) {
     rowKeyToIndex = table.rowKeyToIndex;
     columnKeyToIndex = table.columnKeyToIndex;
     @SuppressWarnings("unchecked")
-    V[][] copy = (V[][]) new Object[rowList.size()][columnList.size()];
+    @Nullable
+    V[][] copy = (@Nullable V[][]) new Object[rowList.size()][columnList.size()];
     array = copy;
     for (int i = 0; i < rowList.size(); i++) {
       System.arraycopy(table.array[i], 0, copy[i], 0, table.array[i].length);
     }
   }
 
-  private abstract static class ArrayMap<K, V> extends IteratorBasedAbstractMap<K, V> {
+  private abstract static class ArrayMap<K, V extends @Nullable Object>
+      extends IteratorBasedAbstractMap<K, V> {
     private final ImmutableMap<K, Integer> keyIndex;
 
     private ArrayMap(ImmutableMap<K, Integer> keyIndex) {
@@ -190,9 +207,11 @@ K getKey(int index) {
 
     abstract String getKeyRole();
 
-    abstract @Nullable V getValue(int index);
+    @ParametricNullness
+    abstract V getValue(int index);
 
-    abstract @Nullable V setValue(int index, V newValue);
+    @ParametricNullness
+    abstract V setValue(int index, @ParametricNullness V newValue);
 
     @Override
     public int size() {
@@ -213,12 +232,14 @@ public K getKey() {
         }
 
         @Override
+        @ParametricNullness
         public V getValue() {
           return ArrayMap.this.getValue(index);
         }
 
         @Override
-        public V setValue(V value) {
+        @ParametricNullness
+        public V setValue(@ParametricNullness V value) {
           return ArrayMap.this.setValue(index, value);
         }
       };
@@ -242,12 +263,13 @@ Spliterator<Entry<K, V>> entrySpliterator() {
     // TODO(lowasser): consider an optimized values() implementation
 
     @Override
-    public boolean containsKey(@Nullable Object key) {
+    public boolean containsKey(@CheckForNull Object key) {
       return keyIndex.containsKey(key);
     }
 
+    @CheckForNull
     @Override
-    public V get(@Nullable Object key) {
+    public V get(@CheckForNull Object key) {
       Integer index = keyIndex.get(key);
       if (index == null) {
         return null;
@@ -257,7 +279,8 @@ public V get(@Nullable Object key) {
     }
 
     @Override
-    public V put(K key, V value) {
+    @CheckForNull
+    public V put(K key, @ParametricNullness V value) {
       Integer index = keyIndex.get(key);
       if (index == null) {
         throw new IllegalArgumentException(
@@ -267,7 +290,8 @@ public V put(K key, V value) {
     }
 
     @Override
-    public V remove(Object key) {
+    @CheckForNull
+    public V remove(@CheckForNull Object key) {
       throw new UnsupportedOperationException();
     }
 
@@ -305,6 +329,7 @@ public ImmutableList<C> columnKeyList() {
    *     or equal to the number of allowed row keys, or {@code columnIndex} is greater than or equal
    *     to the number of allowed column keys
    */
+  @CheckForNull
   public V at(int rowIndex, int columnIndex) {
     // In GWT array access never throws IndexOutOfBoundsException.
     checkElementIndex(rowIndex, rowList.size());
@@ -326,7 +351,8 @@ public V at(int rowIndex, int columnIndex) {
    *     to the number of allowed column keys
    */
   @CanIgnoreReturnValue
-  public V set(int rowIndex, int columnIndex, @Nullable V value) {
+  @CheckForNull
+  public V set(int rowIndex, int columnIndex, @CheckForNull V value) {
     // In GWT array access never throws IndexOutOfBoundsException.
     checkElementIndex(rowIndex, rowList.size());
     checkElementIndex(columnIndex, columnList.size());
@@ -345,9 +371,10 @@ public V set(int rowIndex, int columnIndex, @Nullable V value) {
    * @param valueClass class of values stored in the returned array
    */
   @GwtIncompatible // reflection
-  public V[][] toArray(Class<V> valueClass) {
+  public @Nullable V[][] toArray(Class<V> valueClass) {
     @SuppressWarnings("unchecked") // TODO: safe?
-    V[][] copy = (V[][]) Array.newInstance(valueClass, rowList.size(), columnList.size());
+    @Nullable
+    V[][] copy = (@Nullable V[][]) Array.newInstance(valueClass, rowList.size(), columnList.size());
     for (int i = 0; i < rowList.size(); i++) {
       System.arraycopy(array[i], 0, copy[i], 0, array[i].length);
     }
@@ -369,7 +396,7 @@ public void clear() {
 
   /** Associates the value {@code null} with every pair of allowed row and column keys. */
   public void eraseAll() {
-    for (V[] row : array) {
+    for (@Nullable V[] row : array) {
       Arrays.fill(row, null);
     }
   }
@@ -379,7 +406,7 @@ public void eraseAll() {
    * constructed.
    */
   @Override
-  public boolean contains(@Nullable Object rowKey, @Nullable Object columnKey) {
+  public boolean contains(@CheckForNull Object rowKey, @CheckForNull Object columnKey) {
     return containsRow(rowKey) && containsColumn(columnKey);
   }
 
@@ -388,7 +415,7 @@ public boolean contains(@Nullable Object rowKey, @Nullable Object columnKey) {
    * table was constructed.
    */
   @Override
-  public boolean containsColumn(@Nullable Object columnKey) {
+  public boolean containsColumn(@CheckForNull Object columnKey) {
     return columnKeyToIndex.containsKey(columnKey);
   }
 
@@ -397,13 +424,13 @@ public boolean containsColumn(@Nullable Object columnKey) {
    * constructed.
    */
   @Override
-  public boolean containsRow(@Nullable Object rowKey) {
+  public boolean containsRow(@CheckForNull Object rowKey) {
     return rowKeyToIndex.containsKey(rowKey);
   }
 
   @Override
-  public boolean containsValue(@Nullable Object value) {
-    for (V[] row : array) {
+  public boolean containsValue(@CheckForNull Object value) {
+    for (@Nullable V[] row : array) {
       for (V element : row) {
         if (Objects.equal(value, element)) {
           return true;
@@ -414,7 +441,8 @@ public boolean containsValue(@Nullable Object value) {
   }
 
   @Override
-  public V get(@Nullable Object rowKey, @Nullable Object columnKey) {
+  @CheckForNull
+  public V get(@CheckForNull Object rowKey, @CheckForNull Object columnKey) {
     Integer rowIndex = rowKeyToIndex.get(rowKey);
     Integer columnIndex = columnKeyToIndex.get(columnKey);
     return (rowIndex == null || columnIndex == null) ? null : at(rowIndex, columnIndex);
@@ -436,7 +464,8 @@ public boolean isEmpty() {
    */
   @CanIgnoreReturnValue
   @Override
-  public V put(R rowKey, C columnKey, @Nullable V value) {
+  @CheckForNull
+  public V put(R rowKey, C columnKey, @CheckForNull V value) {
     checkNotNull(rowKey);
     checkNotNull(columnKey);
     Integer rowIndex = rowKeyToIndex.get(rowKey);
@@ -462,7 +491,7 @@ public V put(R rowKey, C columnKey, @Nullable V value) {
    *     in {@link #rowKeySet()} or {@link #columnKeySet()}
    */
   @Override
-  public void putAll(Table<? extends R, ? extends C, ? extends V> table) {
+  public void putAll(Table<? extends R, ? extends C, ? extends @Nullable V> table) {
     super.putAll(table);
   }
 
@@ -476,7 +505,8 @@ public void putAll(Table<? extends R, ? extends C, ? extends V> table) {
   @CanIgnoreReturnValue
   @Override
   @Deprecated
-  public V remove(Object rowKey, Object columnKey) {
+  @CheckForNull
+  public V remove(@CheckForNull Object rowKey, @CheckForNull Object columnKey) {
     throw new UnsupportedOperationException();
   }
 
@@ -494,7 +524,8 @@ public V remove(Object rowKey, Object columnKey) {
    *     for the keys
    */
   @CanIgnoreReturnValue
-  public V erase(@Nullable Object rowKey, @Nullable Object columnKey) {
+  @CheckForNull
+  public V erase(@CheckForNull Object rowKey, @CheckForNull Object columnKey) {
     Integer rowIndex = rowKeyToIndex.get(rowKey);
     Integer columnIndex = columnKeyToIndex.get(columnKey);
     if (rowIndex == null || columnIndex == null) {
@@ -522,28 +553,28 @@ public int size() {
    * @return set of table cells consisting of row key / column key / value triplets
    */
   @Override
-  public Set<Cell<R, C, V>> cellSet() {
+  public Set<Cell<R, C, @Nullable V>> cellSet() {
     return super.cellSet();
   }
 
   @Override
-  Iterator<Cell<R, C, V>> cellIterator() {
-    return new AbstractIndexedListIterator<Cell<R, C, V>>(size()) {
+  Iterator<Cell<R, C, @Nullable V>> cellIterator() {
+    return new AbstractIndexedListIterator<Cell<R, C, @Nullable V>>(size()) {
       @Override
-      protected Cell<R, C, V> get(final int index) {
+      protected Cell<R, C, @Nullable V> get(final int index) {
         return getCell(index);
       }
     };
   }
 
   @Override
-  Spliterator<Cell<R, C, V>> cellSpliterator() {
-    return CollectSpliterators.indexed(
+  Spliterator<Cell<R, C, @Nullable V>> cellSpliterator() {
+    return CollectSpliterators.<Cell<R, C, @Nullable V>>indexed(
         size(), Spliterator.ORDERED | Spliterator.NONNULL | Spliterator.DISTINCT, this::getCell);
   }
 
-  private Cell<R, C, V> getCell(final int index) {
-    return new Tables.AbstractCell<R, C, V>() {
+  private Cell<R, C, @Nullable V> getCell(final int index) {
+    return new Tables.AbstractCell<R, C, @Nullable V>() {
       final int rowIndex = index / columnList.size();
       final int columnIndex = index % columnList.size();
 
@@ -558,12 +589,14 @@ public C getColumnKey() {
       }
 
       @Override
+      @CheckForNull
       public V getValue() {
         return at(rowIndex, columnIndex);
       }
     };
   }
 
+  @CheckForNull
   private V getValue(int index) {
     int rowIndex = index / columnList.size();
     int columnIndex = index % columnList.size();
@@ -582,13 +615,17 @@ private V getValue(int index) {
    * @return the corresponding map from row keys to values
    */
   @Override
-  public Map<R, V> column(C columnKey) {
+  public Map<R, @Nullable V> column(C columnKey) {
     checkNotNull(columnKey);
     Integer columnIndex = columnKeyToIndex.get(columnKey);
-    return (columnIndex == null) ? ImmutableMap.<R, V>of() : new Column(columnIndex);
+    if (columnIndex == null) {
+      return emptyMap();
+    } else {
+      return new Column(columnIndex);
+    }
   }
 
-  private class Column extends ArrayMap<R, V> {
+  private class Column extends ArrayMap<R, @Nullable V> {
     final int columnIndex;
 
     Column(int columnIndex) {
@@ -602,12 +639,14 @@ String getKeyRole() {
     }
 
     @Override
+    @CheckForNull
     V getValue(int index) {
       return at(index, columnIndex);
     }
 
     @Override
-    V setValue(int index, V newValue) {
+    @CheckForNull
+    V setValue(int index, @CheckForNull V newValue) {
       return set(index, columnIndex, newValue);
     }
   }
@@ -623,16 +662,16 @@ public ImmutableSet<C> columnKeySet() {
     return columnKeyToIndex.keySet();
   }
 
-  private transient @Nullable ColumnMap columnMap;
+  @CheckForNull private transient ColumnMap columnMap;
 
   @Override
-  public Map<C, Map<R, V>> columnMap() {
+  public Map<C, Map<R, @Nullable V>> columnMap() {
     ColumnMap map = columnMap;
     return (map == null) ? columnMap = new ColumnMap() : map;
   }
 
   @WeakOuter
-  private class ColumnMap extends ArrayMap<C, Map<R, V>> {
+  private class ColumnMap extends ArrayMap<C, Map<R, @Nullable V>> {
     private ColumnMap() {
       super(columnKeyToIndex);
     }
@@ -643,17 +682,18 @@ String getKeyRole() {
     }
 
     @Override
-    Map<R, V> getValue(int index) {
+    Map<R, @Nullable V> getValue(int index) {
       return new Column(index);
     }
 
     @Override
-    Map<R, V> setValue(int index, Map<R, V> newValue) {
+    Map<R, @Nullable V> setValue(int index, Map<R, @Nullable V> newValue) {
       throw new UnsupportedOperationException();
     }
 
     @Override
-    public Map<R, V> put(C key, Map<R, V> value) {
+    @CheckForNull
+    public Map<R, @Nullable V> put(C key, Map<R, @Nullable V> value) {
       throw new UnsupportedOperationException();
     }
   }
@@ -670,13 +710,17 @@ public Map<R, V> put(C key, Map<R, V> value) {
    * @return the corresponding map from column keys to values
    */
   @Override
-  public Map<C, V> row(R rowKey) {
+  public Map<C, @Nullable V> row(R rowKey) {
     checkNotNull(rowKey);
     Integer rowIndex = rowKeyToIndex.get(rowKey);
-    return (rowIndex == null) ? ImmutableMap.<C, V>of() : new Row(rowIndex);
+    if (rowIndex == null) {
+      return emptyMap();
+    } else {
+      return new Row(rowIndex);
+    }
   }
 
-  private class Row extends ArrayMap<C, V> {
+  private class Row extends ArrayMap<C, @Nullable V> {
     final int rowIndex;
 
     Row(int rowIndex) {
@@ -690,12 +734,14 @@ String getKeyRole() {
     }
 
     @Override
+    @CheckForNull
     V getValue(int index) {
       return at(rowIndex, index);
     }
 
     @Override
-    V setValue(int index, V newValue) {
+    @CheckForNull
+    V setValue(int index, @CheckForNull V newValue) {
       return set(rowIndex, index, newValue);
     }
   }
@@ -711,16 +757,16 @@ public ImmutableSet<R> rowKeySet() {
     return rowKeyToIndex.keySet();
   }
 
-  private transient @Nullable RowMap rowMap;
+  @CheckForNull private transient RowMap rowMap;
 
   @Override
-  public Map<R, Map<C, V>> rowMap() {
+  public Map<R, Map<C, @Nullable V>> rowMap() {
     RowMap map = rowMap;
     return (map == null) ? rowMap = new RowMap() : map;
   }
 
   @WeakOuter
-  private class RowMap extends ArrayMap<R, Map<C, V>> {
+  private class RowMap extends ArrayMap<R, Map<C, @Nullable V>> {
     private RowMap() {
       super(rowKeyToIndex);
     }
@@ -731,17 +777,18 @@ String getKeyRole() {
     }
 
     @Override
-    Map<C, V> getValue(int index) {
+    Map<C, @Nullable V> getValue(int index) {
       return new Row(index);
     }
 
     @Override
-    Map<C, V> setValue(int index, Map<C, V> newValue) {
+    Map<C, @Nullable V> setValue(int index, Map<C, @Nullable V> newValue) {
       throw new UnsupportedOperationException();
     }
 
     @Override
-    public Map<C, V> put(R key, Map<C, V> value) {
+    @CheckForNull
+    public Map<C, @Nullable V> put(R key, Map<C, @Nullable V> value) {
       throw new UnsupportedOperationException();
     }
   }
@@ -756,14 +803,15 @@ public Map<C, V> put(R key, Map<C, V> value) {
    * @return collection of values
    */
   @Override
-  public Collection<V> values() {
+  public Collection<@Nullable V> values() {
     return super.values();
   }
 
   @Override
-  Iterator<V> valuesIterator() {
-    return new AbstractIndexedListIterator<V>(size()) {
+  Iterator<@Nullable V> valuesIterator() {
+    return new AbstractIndexedListIterator<@Nullable V>(size()) {
       @Override
+      @CheckForNull
       protected V get(int index) {
         return getValue(index);
       }
@@ -771,8 +819,8 @@ protected V get(int index) {
   }
 
   @Override
-  Spliterator<V> valuesSpliterator() {
-    return CollectSpliterators.indexed(size(), Spliterator.ORDERED, this::getValue);
+  Spliterator<@Nullable V> valuesSpliterator() {
+    return CollectSpliterators.<@Nullable V>indexed(size(), Spliterator.ORDERED, this::getValue);
   }
 
   private static final long serialVersionUID = 0;
diff --git a/guava/src/com/google/common/collect/BaseImmutableMultimap.java b/guava/src/com/google/common/collect/BaseImmutableMultimap.java
index 6ebdf14f52fa..2e69c2a92e39 100644
--- a/guava/src/com/google/common/collect/BaseImmutableMultimap.java
+++ b/guava/src/com/google/common/collect/BaseImmutableMultimap.java
@@ -22,4 +22,5 @@
  * retaining additional implementation details of {@link ImmutableMultimap}.
  */
 @GwtCompatible
+@ElementTypesAreNonnullByDefault
 abstract class BaseImmutableMultimap<K, V> extends AbstractMultimap<K, V> {}
diff --git a/guava/src/com/google/common/collect/BiMap.java b/guava/src/com/google/common/collect/BiMap.java
index f15e4ddd74eb..9ec8abc4d8a3 100644
--- a/guava/src/com/google/common/collect/BiMap.java
+++ b/guava/src/com/google/common/collect/BiMap.java
@@ -20,6 +20,7 @@
 import com.google.errorprone.annotations.CanIgnoreReturnValue;
 import java.util.Map;
 import java.util.Set;
+import javax.annotation.CheckForNull;
 import org.checkerframework.checker.nullness.qual.Nullable;
 import org.checkerframework.framework.qual.AnnotatedFor;
 
@@ -29,14 +30,15 @@
  * bimap containing the same entries as this bimap but with reversed keys and values.
  *
  * <p>See the Guava User Guide article on <a href=
- * "https://github.com/google/guava/wiki/NewCollectionTypesExplained#bimap"> {@code BiMap}</a>.
+ * "https://github.com/google/guava/wiki/NewCollectionTypesExplained#bimap">{@code BiMap}</a>.
  *
  * @author Kevin Bourrillion
  * @since 2.0
  */
 @GwtCompatible
 @AnnotatedFor({"nullness"})
-public interface BiMap<K, V> extends Map<K, V> {
+@ElementTypesAreNonnullByDefault
+public interface BiMap<K extends @Nullable Object, V extends @Nullable Object> extends Map<K, V> {
   // Modification Operations
 
   /**
@@ -48,8 +50,8 @@ public interface BiMap<K, V> extends Map<K, V> {
    */
   @CanIgnoreReturnValue
   @Override
-  @Nullable
-  V put(@Nullable K key, @Nullable V value);
+  @CheckForNull
+  V put(@ParametricNullness K key, @ParametricNullness V value);
 
   /**
    * An alternate form of {@code put} that silently removes any existing entry with the value {@code
@@ -64,12 +66,14 @@ public interface BiMap<K, V> extends Map<K, V> {
    *
    * @param key the key with which the specified value is to be associated
    * @param value the value to be associated with the specified key
-   * @return the value which was previously associated with the key, which may be {@code null}, or
-   *     {@code null} if there was no previous entry
+   * @return the value that was previously associated with the key, or {@code null} if there was no
+   *     previous entry. (If the bimap contains null values, then {@code forcePut}, like {@code
+   *     put}, returns {@code null} both if the key is absent and if it is present with a null
+   *     value.)
    */
   @CanIgnoreReturnValue
-  @Nullable
-  V forcePut(@Nullable K key, @Nullable V value);
+  @CheckForNull
+  V forcePut(@ParametricNullness K key, @ParametricNullness V value);
 
   // Bulk Operations
 
diff --git a/guava/src/com/google/common/collect/BoundType.java b/guava/src/com/google/common/collect/BoundType.java
index ce038026a078..00ac08c5182c 100644
--- a/guava/src/com/google/common/collect/BoundType.java
+++ b/guava/src/com/google/common/collect/BoundType.java
@@ -24,6 +24,7 @@
  * @since 10.0
  */
 @GwtCompatible
+@ElementTypesAreNonnullByDefault
 public enum BoundType {
   /** The endpoint value <i>is not</i> considered part of the set ("exclusive"). */
   OPEN(false),
@@ -39,8 +40,4 @@ public enum BoundType {
   static BoundType forBoolean(boolean inclusive) {
     return inclusive ? CLOSED : OPEN;
   }
-
-  BoundType flip() {
-    return forBoolean(!inclusive);
-  }
 }
diff --git a/guava/src/com/google/common/collect/ByFunctionOrdering.java b/guava/src/com/google/common/collect/ByFunctionOrdering.java
index 6fdcf87308d4..f72238380ed1 100644
--- a/guava/src/com/google/common/collect/ByFunctionOrdering.java
+++ b/guava/src/com/google/common/collect/ByFunctionOrdering.java
@@ -22,6 +22,7 @@
 import com.google.common.base.Function;
 import com.google.common.base.Objects;
 import java.io.Serializable;
+import javax.annotation.CheckForNull;
 import org.checkerframework.checker.nullness.qual.Nullable;
 import org.checkerframework.dataflow.qual.Pure;
 import org.checkerframework.framework.qual.AnnotatedFor;
@@ -32,7 +33,9 @@
  */
 @AnnotatedFor({"nullness"})
 @GwtCompatible(serializable = true)
-final class ByFunctionOrdering<F, T> extends Ordering<F> implements Serializable {
+@ElementTypesAreNonnullByDefault
+final class ByFunctionOrdering<F extends @Nullable Object, T extends @Nullable Object>
+    extends Ordering<F> implements Serializable {
   final Function<F, ? extends T> function;
   final Ordering<T> ordering;
 
@@ -43,13 +46,13 @@ final class ByFunctionOrdering<F, T> extends Ordering<F> implements Serializable
 
   @Pure
   @Override
-  public int compare(F left, F right) {
+  public int compare(@ParametricNullness F left, @ParametricNullness F right) {
     return ordering.compare(function.apply(left), function.apply(right));
   }
 
   @Pure
   @Override
-  public boolean equals(@Nullable Object object) {
+  public boolean equals(@CheckForNull Object object) {
     if (object == this) {
       return true;
     }
diff --git a/guava/src/com/google/common/collect/CartesianList.java b/guava/src/com/google/common/collect/CartesianList.java
index ebff724c3834..4c31b12998e5 100644
--- a/guava/src/com/google/common/collect/CartesianList.java
+++ b/guava/src/com/google/common/collect/CartesianList.java
@@ -22,7 +22,7 @@
 import java.util.List;
 import java.util.ListIterator;
 import java.util.RandomAccess;
-import org.checkerframework.checker.nullness.qual.Nullable;
+import javax.annotation.CheckForNull;
 
 /**
  * Implementation of {@link Lists#cartesianProduct(List)}.
@@ -30,6 +30,7 @@
  * @author Louis Wasserman
  */
 @GwtCompatible
+@ElementTypesAreNonnullByDefault
 final class CartesianList<E> extends AbstractList<List<E>> implements RandomAccess {
 
   private final transient ImmutableList<List<E>> axes;
@@ -44,7 +45,7 @@ static <E> List<List<E>> create(List<? extends List<? extends E>> lists) {
       }
       axesBuilder.add(copy);
     }
-    return new CartesianList<E>(axesBuilder.build());
+    return new CartesianList<>(axesBuilder.build());
   }
 
   CartesianList(ImmutableList<List<E>> axes) {
@@ -67,7 +68,7 @@ private int getAxisIndexForProductIndex(int index, int axis) {
   }
 
   @Override
-  public int indexOf(Object o) {
+  public int indexOf(@CheckForNull Object o) {
     if (!(o instanceof List)) {
       return -1;
     }
@@ -89,7 +90,7 @@ public int indexOf(Object o) {
   }
 
   @Override
-  public int lastIndexOf(Object o) {
+  public int lastIndexOf(@CheckForNull Object o) {
     if (!(o instanceof List)) {
       return -1;
     }
@@ -111,7 +112,7 @@ public int lastIndexOf(Object o) {
   }
 
   @Override
-  public ImmutableList<E> get(final int index) {
+  public ImmutableList<E> get(int index) {
     checkElementIndex(index, size());
     return new ImmutableList<E>() {
 
@@ -140,7 +141,7 @@ public int size() {
   }
 
   @Override
-  public boolean contains(@Nullable Object object) {
+  public boolean contains(@CheckForNull Object object) {
     if (!(object instanceof List)) {
       return false;
     }
diff --git a/guava/src/com/google/common/collect/ClassToInstanceMap.java b/guava/src/com/google/common/collect/ClassToInstanceMap.java
index f43ae6e039d5..870e3cb7f47f 100644
--- a/guava/src/com/google/common/collect/ClassToInstanceMap.java
+++ b/guava/src/com/google/common/collect/ClassToInstanceMap.java
@@ -20,6 +20,7 @@
 import com.google.errorprone.annotations.CanIgnoreReturnValue;
 import com.google.errorprone.annotations.DoNotMock;
 import java.util.Map;
+import javax.annotation.CheckForNull;
 import org.checkerframework.checker.nullness.qual.Nullable;
 import org.checkerframework.framework.qual.AnnotatedFor;
 
@@ -31,8 +32,19 @@
  * <p>Like any other {@code Map<Class, Object>}, this map may contain entries for primitive types,
  * and a primitive type and its corresponding wrapper type may map to different values.
  *
+ * <p>This class's support for {@code null} requires some explanation: From release 31.0 onward,
+ * Guava specifies the nullness of its types through annotations. In the case of {@code
+ * ClassToInstanceMap}, it specifies that both the key and value types are restricted to
+ * non-nullable types. This specification is reasonable for <i>keys</i>, which must be non-null
+ * classes. This is in contrast to the specification for <i>values</i>: Null values <i>are</i>
+ * supported by the implementation {@link MutableClassToInstanceMap}, even though that
+ * implementation and this interface specify otherwise. Thus, if you use a nullness checker, you can
+ * safely suppress any warnings it produces when you write null values into a {@code
+ * MutableClassToInstanceMap}. Just be sure to be prepared for null values when reading from it,
+ * since nullness checkers will assume that vaules are non-null then, too.
+ *
  * <p>See the Guava User Guide article on <a href=
- * "https://github.com/google/guava/wiki/NewCollectionTypesExplained#classtoinstancemap"> {@code
+ * "https://github.com/google/guava/wiki/NewCollectionTypesExplained#classtoinstancemap">{@code
  * ClassToInstanceMap}</a>.
  *
  * <p>To map a generic type to an instance of that type, use {@link
@@ -45,12 +57,18 @@
 @DoNotMock("Use ImmutableClassToInstanceMap or MutableClassToInstanceMap")
 @GwtCompatible
 @AnnotatedFor({"nullness"})
+@ElementTypesAreNonnullByDefault
+// If we ever support non-null projections (https://github.com/jspecify/jspecify/issues/86), we
+// we might annotate this as...
+// ClassToInstanceMap<B extends @Nullable Object> extends Map<Class<? extends @Nonnull B>, B>
+// ...and change its methods similarly (<T extends @Nonnull B> or Class<@Nonnull T>).
 public interface ClassToInstanceMap<B> extends Map<Class<? extends B>, B> {
   /**
    * Returns the value the specified class is mapped to, or {@code null} if no entry for this class
    * is present. This will only return a value that was bound to this specific class, not a value
    * that may have been bound to a subtype.
    */
+  @CheckForNull
   <T extends B> T getInstance(Class<T> type);
 
   /**
@@ -61,5 +79,6 @@ public interface ClassToInstanceMap<B> extends Map<Class<? extends B>, B> {
    *     null} if there was no previous entry.
    */
   @CanIgnoreReturnValue
-  <T extends B> T putInstance(Class<T> type, @Nullable T value);
+  @CheckForNull
+  <T extends B> T putInstance(Class<T> type, T value);
 }
diff --git a/guava/src/com/google/common/collect/CollectCollectors.java b/guava/src/com/google/common/collect/CollectCollectors.java
index a49b0a04f2f3..f582660c8ee1 100644
--- a/guava/src/com/google/common/collect/CollectCollectors.java
+++ b/guava/src/com/google/common/collect/CollectCollectors.java
@@ -17,8 +17,8 @@
 package com.google.common.collect;
 
 import static com.google.common.base.Preconditions.checkNotNull;
+import static java.util.stream.Collectors.collectingAndThen;
 
-import com.google.common.annotations.Beta;
 import com.google.common.annotations.GwtCompatible;
 import com.google.common.annotations.GwtIncompatible;
 import com.google.common.base.Preconditions;
@@ -35,10 +35,12 @@
 import java.util.stream.Collector;
 import java.util.stream.Collectors;
 import java.util.stream.Stream;
+import javax.annotation.CheckForNull;
 import org.checkerframework.checker.nullness.qual.Nullable;
 
 /** Collectors utilities for {@code common.collect} internals. */
 @GwtCompatible
+@ElementTypesAreNonnullByDefault
 final class CollectCollectors {
 
   private static final Collector<Object, ?, ImmutableList<Object>> TO_IMMUTABLE_LIST =
@@ -104,7 +106,7 @@ private static final class EnumSetAccumulator<E extends Enum<E>> {
                 EnumSetAccumulator::toImmutableSet,
                 Collector.Characteristics.UNORDERED);
 
-    private @Nullable EnumSet<E> set;
+    @CheckForNull private EnumSet<E> set;
 
     void add(E e) {
       if (set == null) {
@@ -139,7 +141,7 @@ ImmutableSet<E> toImmutableSet() {
 
   // Multisets
 
-  static <T, E> Collector<T, ?, ImmutableMultiset<E>> toImmutableMultiset(
+  static <T extends @Nullable Object, E> Collector<T, ?, ImmutableMultiset<E>> toImmutableMultiset(
       Function<? super T, ? extends E> elementFunction, ToIntFunction<? super T> countFunction) {
     checkNotNull(elementFunction);
     checkNotNull(countFunction);
@@ -154,10 +156,11 @@ ImmutableSet<E> toImmutableSet() {
         (Multiset<E> multiset) -> ImmutableMultiset.copyFromEntries(multiset.entrySet()));
   }
 
-  static <T, E, M extends Multiset<E>> Collector<T, ?, M> toMultiset(
-      Function<? super T, E> elementFunction,
-      ToIntFunction<? super T> countFunction,
-      Supplier<M> multisetSupplier) {
+  static <T extends @Nullable Object, E extends @Nullable Object, M extends Multiset<E>>
+      Collector<T, ?, M> toMultiset(
+          Function<? super T, E> elementFunction,
+          ToIntFunction<? super T> countFunction,
+          Supplier<M> multisetSupplier) {
     checkNotNull(elementFunction);
     checkNotNull(countFunction);
     checkNotNull(multisetSupplier);
@@ -172,7 +175,7 @@ ImmutableSet<E> toImmutableSet() {
 
   // Maps
 
-  static <T, K, V> Collector<T, ?, ImmutableMap<K, V>> toImmutableMap(
+  static <T extends @Nullable Object, K, V> Collector<T, ?, ImmutableMap<K, V>> toImmutableMap(
       Function<? super T, ? extends K> keyFunction,
       Function<? super T, ? extends V> valueFunction) {
     checkNotNull(keyFunction);
@@ -184,28 +187,30 @@ ImmutableSet<E> toImmutableSet() {
         ImmutableMap.Builder::build);
   }
 
-  public static <T, K, V> Collector<T, ?, ImmutableMap<K, V>> toImmutableMap(
-      Function<? super T, ? extends K> keyFunction,
-      Function<? super T, ? extends V> valueFunction,
-      BinaryOperator<V> mergeFunction) {
+  public static <T extends @Nullable Object, K, V>
+      Collector<T, ?, ImmutableMap<K, V>> toImmutableMap(
+          Function<? super T, ? extends K> keyFunction,
+          Function<? super T, ? extends V> valueFunction,
+          BinaryOperator<V> mergeFunction) {
     checkNotNull(keyFunction);
     checkNotNull(valueFunction);
     checkNotNull(mergeFunction);
-    return Collectors.collectingAndThen(
+    return collectingAndThen(
         Collectors.toMap(keyFunction, valueFunction, mergeFunction, LinkedHashMap::new),
         ImmutableMap::copyOf);
   }
 
-  static <T, K, V> Collector<T, ?, ImmutableSortedMap<K, V>> toImmutableSortedMap(
-      Comparator<? super K> comparator,
-      Function<? super T, ? extends K> keyFunction,
-      Function<? super T, ? extends V> valueFunction) {
+  static <T extends @Nullable Object, K, V>
+      Collector<T, ?, ImmutableSortedMap<K, V>> toImmutableSortedMap(
+          Comparator<? super K> comparator,
+          Function<? super T, ? extends K> keyFunction,
+          Function<? super T, ? extends V> valueFunction) {
     checkNotNull(comparator);
     checkNotNull(keyFunction);
     checkNotNull(valueFunction);
     /*
      * We will always fail if there are duplicate keys, and the keys are always sorted by
-     * the Comparator, so the entries can come in in arbitrary order -- so we report UNORDERED.
+     * the Comparator, so the entries can come in an arbitrary order -- so we report UNORDERED.
      */
     return Collector.of(
         () -> new ImmutableSortedMap.Builder<K, V>(comparator),
@@ -215,22 +220,23 @@ ImmutableSet<E> toImmutableSet() {
         Collector.Characteristics.UNORDERED);
   }
 
-  static <T, K, V> Collector<T, ?, ImmutableSortedMap<K, V>> toImmutableSortedMap(
-      Comparator<? super K> comparator,
-      Function<? super T, ? extends K> keyFunction,
-      Function<? super T, ? extends V> valueFunction,
-      BinaryOperator<V> mergeFunction) {
+  static <T extends @Nullable Object, K, V>
+      Collector<T, ?, ImmutableSortedMap<K, V>> toImmutableSortedMap(
+          Comparator<? super K> comparator,
+          Function<? super T, ? extends K> keyFunction,
+          Function<? super T, ? extends V> valueFunction,
+          BinaryOperator<V> mergeFunction) {
     checkNotNull(comparator);
     checkNotNull(keyFunction);
     checkNotNull(valueFunction);
     checkNotNull(mergeFunction);
-    return Collectors.collectingAndThen(
+    return collectingAndThen(
         Collectors.toMap(
             keyFunction, valueFunction, mergeFunction, () -> new TreeMap<K, V>(comparator)),
         ImmutableSortedMap::copyOfSorted);
   }
 
-  static <T, K, V> Collector<T, ?, ImmutableBiMap<K, V>> toImmutableBiMap(
+  static <T extends @Nullable Object, K, V> Collector<T, ?, ImmutableBiMap<K, V>> toImmutableBiMap(
       Function<? super T, ? extends K> keyFunction,
       Function<? super T, ? extends V> valueFunction) {
     checkNotNull(keyFunction);
@@ -243,9 +249,10 @@ ImmutableSet<E> toImmutableSet() {
         new Collector.Characteristics[0]);
   }
 
-  static <T, K extends Enum<K>, V> Collector<T, ?, ImmutableMap<K, V>> toImmutableEnumMap(
-      Function<? super T, ? extends K> keyFunction,
-      Function<? super T, ? extends V> valueFunction) {
+  static <T extends @Nullable Object, K extends Enum<K>, V>
+      Collector<T, ?, ImmutableMap<K, V>> toImmutableEnumMap(
+          Function<? super T, ? extends K> keyFunction,
+          Function<? super T, ? extends V> valueFunction) {
     checkNotNull(keyFunction);
     checkNotNull(valueFunction);
     return Collector.of(
@@ -255,19 +262,26 @@ ImmutableSet<E> toImmutableSet() {
                   throw new IllegalArgumentException("Multiple values for key: " + v1 + ", " + v2);
                 }),
         (accum, t) -> {
-          K key = checkNotNull(keyFunction.apply(t), "Null key for input %s", t);
-          V newValue = checkNotNull(valueFunction.apply(t), "Null value for input %s", t);
-          accum.put(key, newValue);
+          /*
+           * We assign these to variables before calling checkNotNull to work around a bug in our
+           * nullness checker.
+           */
+          K key = keyFunction.apply(t);
+          V newValue = valueFunction.apply(t);
+          accum.put(
+              checkNotNull(key, "Null key for input %s", t),
+              checkNotNull(newValue, "Null value for input %s", t));
         },
         EnumMapAccumulator::combine,
         EnumMapAccumulator::toImmutableMap,
         Collector.Characteristics.UNORDERED);
   }
 
-  static <T, K extends Enum<K>, V> Collector<T, ?, ImmutableMap<K, V>> toImmutableEnumMap(
-      Function<? super T, ? extends K> keyFunction,
-      Function<? super T, ? extends V> valueFunction,
-      BinaryOperator<V> mergeFunction) {
+  static <T extends @Nullable Object, K extends Enum<K>, V>
+      Collector<T, ?, ImmutableMap<K, V>> toImmutableEnumMap(
+          Function<? super T, ? extends K> keyFunction,
+          Function<? super T, ? extends V> valueFunction,
+          BinaryOperator<V> mergeFunction) {
     checkNotNull(keyFunction);
     checkNotNull(valueFunction);
     checkNotNull(mergeFunction);
@@ -275,9 +289,15 @@ ImmutableSet<E> toImmutableSet() {
     return Collector.of(
         () -> new EnumMapAccumulator<K, V>(mergeFunction),
         (accum, t) -> {
-          K key = checkNotNull(keyFunction.apply(t), "Null key for input %s", t);
-          V newValue = checkNotNull(valueFunction.apply(t), "Null value for input %s", t);
-          accum.put(key, newValue);
+          /*
+           * We assign these to variables before calling checkNotNull to work around a bug in our
+           * nullness checker.
+           */
+          K key = keyFunction.apply(t);
+          V newValue = valueFunction.apply(t);
+          accum.put(
+              checkNotNull(key, "Null key for input %s", t),
+              checkNotNull(newValue, "Null value for input %s", t));
         },
         EnumMapAccumulator::combine,
         EnumMapAccumulator::toImmutableMap);
@@ -285,7 +305,7 @@ ImmutableSet<E> toImmutableSet() {
 
   private static class EnumMapAccumulator<K extends Enum<K>, V> {
     private final BinaryOperator<V> mergeFunction;
-    private EnumMap<K, V> map = null;
+    @CheckForNull private EnumMap<K, V> map = null;
 
     EnumMapAccumulator(BinaryOperator<V> mergeFunction) {
       this.mergeFunction = mergeFunction;
@@ -315,7 +335,7 @@ ImmutableMap<K, V> toImmutableMap() {
   }
 
   @GwtIncompatible
-  static <T, K extends Comparable<? super K>, V>
+  static <T extends @Nullable Object, K extends Comparable<? super K>, V>
       Collector<T, ?, ImmutableRangeMap<K, V>> toImmutableRangeMap(
           Function<? super T, Range<K>> keyFunction,
           Function<? super T, ? extends V> valueFunction) {
@@ -330,9 +350,10 @@ ImmutableMap<K, V> toImmutableMap() {
 
   // Multimaps
 
-  static <T, K, V> Collector<T, ?, ImmutableListMultimap<K, V>> toImmutableListMultimap(
-      Function<? super T, ? extends K> keyFunction,
-      Function<? super T, ? extends V> valueFunction) {
+  static <T extends @Nullable Object, K, V>
+      Collector<T, ?, ImmutableListMultimap<K, V>> toImmutableListMultimap(
+          Function<? super T, ? extends K> keyFunction,
+          Function<? super T, ? extends V> valueFunction) {
     checkNotNull(keyFunction, "keyFunction");
     checkNotNull(valueFunction, "valueFunction");
     return Collector.of(
@@ -342,12 +363,13 @@ ImmutableMap<K, V> toImmutableMap() {
         ImmutableListMultimap.Builder::build);
   }
 
-  static <T, K, V> Collector<T, ?, ImmutableListMultimap<K, V>> flatteningToImmutableListMultimap(
-      Function<? super T, ? extends K> keyFunction,
-      Function<? super T, ? extends Stream<? extends V>> valuesFunction) {
+  static <T extends @Nullable Object, K, V>
+      Collector<T, ?, ImmutableListMultimap<K, V>> flatteningToImmutableListMultimap(
+          Function<? super T, ? extends K> keyFunction,
+          Function<? super T, ? extends Stream<? extends V>> valuesFunction) {
     checkNotNull(keyFunction);
     checkNotNull(valuesFunction);
-    return Collectors.collectingAndThen(
+    return collectingAndThen(
         flatteningToMultimap(
             input -> checkNotNull(keyFunction.apply(input)),
             input -> valuesFunction.apply(input).peek(Preconditions::checkNotNull),
@@ -355,9 +377,10 @@ ImmutableMap<K, V> toImmutableMap() {
         ImmutableListMultimap::copyOf);
   }
 
-  static <T, K, V> Collector<T, ?, ImmutableSetMultimap<K, V>> toImmutableSetMultimap(
-      Function<? super T, ? extends K> keyFunction,
-      Function<? super T, ? extends V> valueFunction) {
+  static <T extends @Nullable Object, K, V>
+      Collector<T, ?, ImmutableSetMultimap<K, V>> toImmutableSetMultimap(
+          Function<? super T, ? extends K> keyFunction,
+          Function<? super T, ? extends V> valueFunction) {
     checkNotNull(keyFunction, "keyFunction");
     checkNotNull(valueFunction, "valueFunction");
     return Collector.of(
@@ -367,12 +390,13 @@ ImmutableMap<K, V> toImmutableMap() {
         ImmutableSetMultimap.Builder::build);
   }
 
-  static <T, K, V> Collector<T, ?, ImmutableSetMultimap<K, V>> flatteningToImmutableSetMultimap(
-      Function<? super T, ? extends K> keyFunction,
-      Function<? super T, ? extends Stream<? extends V>> valuesFunction) {
+  static <T extends @Nullable Object, K, V>
+      Collector<T, ?, ImmutableSetMultimap<K, V>> flatteningToImmutableSetMultimap(
+          Function<? super T, ? extends K> keyFunction,
+          Function<? super T, ? extends Stream<? extends V>> valuesFunction) {
     checkNotNull(keyFunction);
     checkNotNull(valuesFunction);
-    return Collectors.collectingAndThen(
+    return collectingAndThen(
         flatteningToMultimap(
             input -> checkNotNull(keyFunction.apply(input)),
             input -> valuesFunction.apply(input).peek(Preconditions::checkNotNull),
@@ -380,10 +404,15 @@ ImmutableMap<K, V> toImmutableMap() {
         ImmutableSetMultimap::copyOf);
   }
 
-  static <T, K, V, M extends Multimap<K, V>> Collector<T, ?, M> toMultimap(
-      Function<? super T, ? extends K> keyFunction,
-      Function<? super T, ? extends V> valueFunction,
-      Supplier<M> multimapSupplier) {
+  static <
+          T extends @Nullable Object,
+          K extends @Nullable Object,
+          V extends @Nullable Object,
+          M extends Multimap<K, V>>
+      Collector<T, ?, M> toMultimap(
+          Function<? super T, ? extends K> keyFunction,
+          Function<? super T, ? extends V> valueFunction,
+          Supplier<M> multimapSupplier) {
     checkNotNull(keyFunction);
     checkNotNull(valueFunction);
     checkNotNull(multimapSupplier);
@@ -396,11 +425,15 @@ ImmutableMap<K, V> toImmutableMap() {
         });
   }
 
-  @Beta
-  static <T, K, V, M extends Multimap<K, V>> Collector<T, ?, M> flatteningToMultimap(
-      Function<? super T, ? extends K> keyFunction,
-      Function<? super T, ? extends Stream<? extends V>> valueFunction,
-      Supplier<M> multimapSupplier) {
+  static <
+          T extends @Nullable Object,
+          K extends @Nullable Object,
+          V extends @Nullable Object,
+          M extends Multimap<K, V>>
+      Collector<T, ?, M> flatteningToMultimap(
+          Function<? super T, ? extends K> keyFunction,
+          Function<? super T, ? extends Stream<? extends V>> valueFunction,
+          Supplier<M> multimapSupplier) {
     checkNotNull(keyFunction);
     checkNotNull(valueFunction);
     checkNotNull(multimapSupplier);
diff --git a/guava/src/com/google/common/collect/CollectPreconditions.java b/guava/src/com/google/common/collect/CollectPreconditions.java
index 98b30c6d5e7b..c649b03233e3 100644
--- a/guava/src/com/google/common/collect/CollectPreconditions.java
+++ b/guava/src/com/google/common/collect/CollectPreconditions.java
@@ -23,6 +23,7 @@
 
 /** Precondition checks useful in collection implementations. */
 @GwtCompatible
+@ElementTypesAreNonnullByDefault
 final class CollectPreconditions {
 
   static void checkEntryNotNull(Object key, Object value) {
diff --git a/guava/src/com/google/common/collect/CollectSpliterators.java b/guava/src/com/google/common/collect/CollectSpliterators.java
index 6bced4aa8e6e..7d0e82f203a8 100644
--- a/guava/src/com/google/common/collect/CollectSpliterators.java
+++ b/guava/src/com/google/common/collect/CollectSpliterators.java
@@ -18,6 +18,8 @@
 
 import static com.google.common.base.Preconditions.checkArgument;
 import static com.google.common.base.Preconditions.checkNotNull;
+import static com.google.common.collect.NullnessCasts.uncheckedCastNullableTToT;
+import static java.lang.Math.max;
 
 import com.google.common.annotations.GwtCompatible;
 import com.google.j2objc.annotations.Weak;
@@ -31,22 +33,25 @@
 import java.util.function.LongConsumer;
 import java.util.function.Predicate;
 import java.util.stream.IntStream;
+import javax.annotation.CheckForNull;
 import org.checkerframework.checker.nullness.qual.Nullable;
 
 /** Spliterator utilities for {@code common.collect} internals. */
 @GwtCompatible
+@ElementTypesAreNonnullByDefault
 final class CollectSpliterators {
   private CollectSpliterators() {}
 
-  static <T> Spliterator<T> indexed(int size, int extraCharacteristics, IntFunction<T> function) {
+  static <T extends @Nullable Object> Spliterator<T> indexed(
+      int size, int extraCharacteristics, IntFunction<T> function) {
     return indexed(size, extraCharacteristics, function, null);
   }
 
-  static <T> Spliterator<T> indexed(
+  static <T extends @Nullable Object> Spliterator<T> indexed(
       int size,
       int extraCharacteristics,
       IntFunction<T> function,
-      Comparator<? super T> comparator) {
+      @CheckForNull Comparator<? super T> comparator) {
     if (comparator != null) {
       checkArgument((extraCharacteristics & Spliterator.SORTED) != 0);
     }
@@ -68,7 +73,8 @@ public void forEachRemaining(Consumer<? super T> action) {
       }
 
       @Override
-      public @Nullable Spliterator<T> trySplit() {
+      @CheckForNull
+      public Spliterator<T> trySplit() {
         Spliterator.OfInt split = delegate.trySplit();
         return (split == null) ? null : new WithCharacteristics(split);
       }
@@ -87,6 +93,7 @@ public int characteristics() {
       }
 
       @Override
+      @CheckForNull
       public Comparator<? super T> getComparator() {
         if (hasCharacteristics(Spliterator.SORTED)) {
           return comparator;
@@ -102,9 +109,10 @@ public Comparator<? super T> getComparator() {
    * Returns a {@code Spliterator} over the elements of {@code fromSpliterator} mapped by {@code
    * function}.
    */
-  static <InElementT, OutElementT> Spliterator<OutElementT> map(
-      Spliterator<InElementT> fromSpliterator,
-      Function<? super InElementT, ? extends OutElementT> function) {
+  static <InElementT extends @Nullable Object, OutElementT extends @Nullable Object>
+      Spliterator<OutElementT> map(
+          Spliterator<InElementT> fromSpliterator,
+          Function<? super InElementT, ? extends OutElementT> function) {
     checkNotNull(fromSpliterator);
     checkNotNull(function);
     return new Spliterator<OutElementT>() {
@@ -121,6 +129,7 @@ public void forEachRemaining(Consumer<? super OutElementT> action) {
       }
 
       @Override
+      @CheckForNull
       public Spliterator<OutElementT> trySplit() {
         Spliterator<InElementT> fromSplit = fromSpliterator.trySplit();
         return (fromSplit != null) ? map(fromSplit, function) : null;
@@ -140,14 +149,15 @@ public int characteristics() {
   }
 
   /** Returns a {@code Spliterator} filtered by the specified predicate. */
-  static <T> Spliterator<T> filter(Spliterator<T> fromSpliterator, Predicate<? super T> predicate) {
+  static <T extends @Nullable Object> Spliterator<T> filter(
+      Spliterator<T> fromSpliterator, Predicate<? super T> predicate) {
     checkNotNull(fromSpliterator);
     checkNotNull(predicate);
     class Splitr implements Spliterator<T>, Consumer<T> {
-      T holder = null;
+      @CheckForNull T holder = null;
 
       @Override
-      public void accept(T t) {
+      public void accept(@ParametricNullness T t) {
         this.holder = t;
       }
 
@@ -155,8 +165,10 @@ public void accept(T t) {
       public boolean tryAdvance(Consumer<? super T> action) {
         while (fromSpliterator.tryAdvance(this)) {
           try {
-            if (predicate.test(holder)) {
-              action.accept(holder);
+            // The cast is safe because tryAdvance puts a T into `holder`.
+            T next = uncheckedCastNullableTToT(holder);
+            if (predicate.test(next)) {
+              action.accept(next);
               return true;
             }
           } finally {
@@ -167,6 +179,7 @@ public boolean tryAdvance(Consumer<? super T> action) {
       }
 
       @Override
+      @CheckForNull
       public Spliterator<T> trySplit() {
         Spliterator<T> fromSplit = fromSpliterator.trySplit();
         return (fromSplit == null) ? null : filter(fromSplit, predicate);
@@ -178,6 +191,7 @@ public long estimateSize() {
       }
 
       @Override
+      @CheckForNull
       public Comparator<? super T> getComparator() {
         return fromSpliterator.getComparator();
       }
@@ -198,11 +212,12 @@ public int characteristics() {
    * Returns a {@code Spliterator} that iterates over the elements of the spliterators generated by
    * applying {@code function} to the elements of {@code fromSpliterator}.
    */
-  static <InElementT, OutElementT> Spliterator<OutElementT> flatMap(
-      Spliterator<InElementT> fromSpliterator,
-      Function<? super InElementT, Spliterator<OutElementT>> function,
-      int topCharacteristics,
-      long topSize) {
+  static <InElementT extends @Nullable Object, OutElementT extends @Nullable Object>
+      Spliterator<OutElementT> flatMap(
+          Spliterator<InElementT> fromSpliterator,
+          Function<? super InElementT, Spliterator<OutElementT>> function,
+          int topCharacteristics,
+          long topSize) {
     checkArgument(
         (topCharacteristics & Spliterator.SUBSIZED) == 0,
         "flatMap does not support SUBSIZED characteristic");
@@ -211,7 +226,7 @@ static <InElementT, OutElementT> Spliterator<OutElementT> flatMap(
         "flatMap does not support SORTED characteristic");
     checkNotNull(fromSpliterator);
     checkNotNull(function);
-    return new FlatMapSpliteratorOfObject<InElementT, OutElementT>(
+    return new FlatMapSpliteratorOfObject<>(
         null, fromSpliterator, function, topCharacteristics, topSize);
   }
 
@@ -220,7 +235,7 @@ static <InElementT, OutElementT> Spliterator<OutElementT> flatMap(
    * generated by applying {@code function} to the elements of {@code fromSpliterator}. (If {@code
    * function} returns {@code null} for an input, it is replaced with an empty stream.)
    */
-  static <InElementT> Spliterator.OfInt flatMapToInt(
+  static <InElementT extends @Nullable Object> Spliterator.OfInt flatMapToInt(
       Spliterator<InElementT> fromSpliterator,
       Function<? super InElementT, Spliterator.OfInt> function,
       int topCharacteristics,
@@ -233,7 +248,7 @@ static <InElementT> Spliterator.OfInt flatMapToInt(
         "flatMap does not support SORTED characteristic");
     checkNotNull(fromSpliterator);
     checkNotNull(function);
-    return new FlatMapSpliteratorOfInt<InElementT>(
+    return new FlatMapSpliteratorOfInt<>(
         null, fromSpliterator, function, topCharacteristics, topSize);
   }
 
@@ -242,7 +257,7 @@ static <InElementT> Spliterator.OfInt flatMapToInt(
    * generated by applying {@code function} to the elements of {@code fromSpliterator}. (If {@code
    * function} returns {@code null} for an input, it is replaced with an empty stream.)
    */
-  static <InElementT> Spliterator.OfLong flatMapToLong(
+  static <InElementT extends @Nullable Object> Spliterator.OfLong flatMapToLong(
       Spliterator<InElementT> fromSpliterator,
       Function<? super InElementT, Spliterator.OfLong> function,
       int topCharacteristics,
@@ -255,7 +270,7 @@ static <InElementT> Spliterator.OfLong flatMapToLong(
         "flatMap does not support SORTED characteristic");
     checkNotNull(fromSpliterator);
     checkNotNull(function);
-    return new FlatMapSpliteratorOfLong<InElementT>(
+    return new FlatMapSpliteratorOfLong<>(
         null, fromSpliterator, function, topCharacteristics, topSize);
   }
 
@@ -264,7 +279,7 @@ static <InElementT> Spliterator.OfLong flatMapToLong(
    * generated by applying {@code function} to the elements of {@code fromSpliterator}. (If {@code
    * function} returns {@code null} for an input, it is replaced with an empty stream.)
    */
-  static <InElementT> Spliterator.OfDouble flatMapToDouble(
+  static <InElementT extends @Nullable Object> Spliterator.OfDouble flatMapToDouble(
       Spliterator<InElementT> fromSpliterator,
       Function<? super InElementT, Spliterator.OfDouble> function,
       int topCharacteristics,
@@ -277,7 +292,7 @@ static <InElementT> Spliterator.OfDouble flatMapToDouble(
         "flatMap does not support SORTED characteristic");
     checkNotNull(fromSpliterator);
     checkNotNull(function);
-    return new FlatMapSpliteratorOfDouble<InElementT>(
+    return new FlatMapSpliteratorOfDouble<>(
         null, fromSpliterator, function, topCharacteristics, topSize);
   }
 
@@ -289,20 +304,22 @@ static <InElementT> Spliterator.OfDouble flatMapToDouble(
    * @param <OutSpliteratorT> the type of the output spliterators
    */
   abstract static class FlatMapSpliterator<
-          InElementT, OutElementT, OutSpliteratorT extends Spliterator<OutElementT>>
+          InElementT extends @Nullable Object,
+          OutElementT extends @Nullable Object,
+          OutSpliteratorT extends Spliterator<OutElementT>>
       implements Spliterator<OutElementT> {
     /** Factory for constructing {@link FlatMapSpliterator} instances. */
     @FunctionalInterface
-    interface Factory<InElementT, OutSpliteratorT extends Spliterator<?>> {
+    interface Factory<InElementT extends @Nullable Object, OutSpliteratorT extends Spliterator<?>> {
       OutSpliteratorT newFlatMapSpliterator(
-          OutSpliteratorT prefix,
+          @CheckForNull OutSpliteratorT prefix,
           Spliterator<InElementT> fromSplit,
           Function<? super InElementT, OutSpliteratorT> function,
           int splitCharacteristics,
           long estSplitSize);
     }
 
-    @Weak @Nullable OutSpliteratorT prefix;
+    @Weak @CheckForNull OutSpliteratorT prefix;
     final Spliterator<InElementT> from;
     final Function<? super InElementT, OutSpliteratorT> function;
     final Factory<InElementT, OutSpliteratorT> factory;
@@ -310,7 +327,7 @@ OutSpliteratorT newFlatMapSpliterator(
     long estimatedSize;
 
     FlatMapSpliterator(
-        OutSpliteratorT prefix,
+        @CheckForNull OutSpliteratorT prefix,
         Spliterator<InElementT> from,
         Function<? super InElementT, OutSpliteratorT> function,
         Factory<InElementT, OutSpliteratorT> factory,
@@ -365,6 +382,7 @@ public final void forEachRemaining(Consumer<? super OutElementT> action) {
     }
 
     @Override
+    @CheckForNull
     public final OutSpliteratorT trySplit() {
       Spliterator<InElementT> fromSplit = from.trySplit();
       if (fromSplit != null) {
@@ -392,9 +410,9 @@ public final OutSpliteratorT trySplit() {
     @Override
     public final long estimateSize() {
       if (prefix != null) {
-        estimatedSize = Math.max(estimatedSize, prefix.estimateSize());
+        estimatedSize = max(estimatedSize, prefix.estimateSize());
       }
-      return Math.max(estimatedSize, 0);
+      return max(estimatedSize, 0);
     }
 
     @Override
@@ -414,10 +432,11 @@ public final int characteristics() {
    * @param <InElementT> the element type of the input spliterator
    * @param <OutElementT> the element type of the output spliterators
    */
-  static final class FlatMapSpliteratorOfObject<InElementT, OutElementT>
+  static final class FlatMapSpliteratorOfObject<
+          InElementT extends @Nullable Object, OutElementT extends @Nullable Object>
       extends FlatMapSpliterator<InElementT, OutElementT, Spliterator<OutElementT>> {
     FlatMapSpliteratorOfObject(
-        Spliterator<OutElementT> prefix,
+        @CheckForNull Spliterator<OutElementT> prefix,
         Spliterator<InElementT> from,
         Function<? super InElementT, Spliterator<OutElementT>> function,
         int characteristics,
@@ -436,8 +455,8 @@ static final class FlatMapSpliteratorOfObject<InElementT, OutElementT>
    * @param <OutSpliteratorT> the primitive spliterator type associated with {@code OutElementT}
    */
   abstract static class FlatMapSpliteratorOfPrimitive<
-          InElementT,
-          OutElementT,
+          InElementT extends @Nullable Object,
+          OutElementT extends @Nullable Object,
           OutConsumerT,
           OutSpliteratorT extends
               Spliterator.OfPrimitive<OutElementT, OutConsumerT, OutSpliteratorT>>
@@ -445,7 +464,7 @@ abstract static class FlatMapSpliteratorOfPrimitive<
       implements Spliterator.OfPrimitive<OutElementT, OutConsumerT, OutSpliteratorT> {
 
     FlatMapSpliteratorOfPrimitive(
-        OutSpliteratorT prefix,
+        @CheckForNull OutSpliteratorT prefix,
         Spliterator<InElementT> from,
         Function<? super InElementT, OutSpliteratorT> function,
         Factory<InElementT, OutSpliteratorT> factory,
@@ -489,11 +508,11 @@ public final void forEachRemaining(OutConsumerT action) {
   }
 
   /** Implementation of {@link #flatMapToInt}. */
-  static final class FlatMapSpliteratorOfInt<InElementT>
+  static final class FlatMapSpliteratorOfInt<InElementT extends @Nullable Object>
       extends FlatMapSpliteratorOfPrimitive<InElementT, Integer, IntConsumer, Spliterator.OfInt>
       implements Spliterator.OfInt {
     FlatMapSpliteratorOfInt(
-        Spliterator.OfInt prefix,
+        @CheckForNull Spliterator.OfInt prefix,
         Spliterator<InElementT> from,
         Function<? super InElementT, Spliterator.OfInt> function,
         int characteristics,
@@ -503,11 +522,11 @@ static final class FlatMapSpliteratorOfInt<InElementT>
   }
 
   /** Implementation of {@link #flatMapToLong}. */
-  static final class FlatMapSpliteratorOfLong<InElementT>
+  static final class FlatMapSpliteratorOfLong<InElementT extends @Nullable Object>
       extends FlatMapSpliteratorOfPrimitive<InElementT, Long, LongConsumer, Spliterator.OfLong>
       implements Spliterator.OfLong {
     FlatMapSpliteratorOfLong(
-        Spliterator.OfLong prefix,
+        @CheckForNull Spliterator.OfLong prefix,
         Spliterator<InElementT> from,
         Function<? super InElementT, Spliterator.OfLong> function,
         int characteristics,
@@ -517,12 +536,12 @@ static final class FlatMapSpliteratorOfLong<InElementT>
   }
 
   /** Implementation of {@link #flatMapToDouble}. */
-  static final class FlatMapSpliteratorOfDouble<InElementT>
+  static final class FlatMapSpliteratorOfDouble<InElementT extends @Nullable Object>
       extends FlatMapSpliteratorOfPrimitive<
           InElementT, Double, DoubleConsumer, Spliterator.OfDouble>
       implements Spliterator.OfDouble {
     FlatMapSpliteratorOfDouble(
-        Spliterator.OfDouble prefix,
+        @CheckForNull Spliterator.OfDouble prefix,
         Spliterator<InElementT> from,
         Function<? super InElementT, Spliterator.OfDouble> function,
         int characteristics,
diff --git a/guava/src/com/google/common/collect/Collections2.java b/guava/src/com/google/common/collect/Collections2.java
index 41013a2aa4a2..fc9e534c7929 100644
--- a/guava/src/com/google/common/collect/Collections2.java
+++ b/guava/src/com/google/common/collect/Collections2.java
@@ -19,6 +19,7 @@
 import static com.google.common.base.Preconditions.checkArgument;
 import static com.google.common.base.Preconditions.checkNotNull;
 import static com.google.common.collect.CollectPreconditions.checkNonnegative;
+import static java.util.Objects.requireNonNull;
 
 import com.google.common.annotations.Beta;
 import com.google.common.annotations.GwtCompatible;
@@ -37,6 +38,7 @@
 import java.util.List;
 import java.util.Spliterator;
 import java.util.function.Consumer;
+import javax.annotation.CheckForNull;
 import org.checkerframework.checker.nullness.qual.Nullable;
 import org.checkerframework.dataflow.qual.Pure;
 import org.checkerframework.framework.qual.AnnotatedFor;
@@ -56,6 +58,7 @@
  */
 @AnnotatedFor({"nullness"})
 @GwtCompatible
+@ElementTypesAreNonnullByDefault
 public final class Collections2 {
   private Collections2() {}
 
@@ -86,7 +89,8 @@ private Collections2() {}
    */
   // TODO(kevinb): how can we omit that Iterables link when building gwt
   // javadoc?
-  public static <E> Collection<E> filter(Collection<E> unfiltered, Predicate<? super E> predicate) {
+  public static <E extends @Nullable Object> Collection<E> filter(
+      Collection<E> unfiltered, Predicate<? super E> predicate) {
     if (unfiltered instanceof FilteredCollection) {
       // Support clear(), removeAll(), and retainAll() when filtering a filtered
       // collection.
@@ -100,7 +104,7 @@ public static <E> Collection<E> filter(Collection<E> unfiltered, Predicate<? sup
    * Delegates to {@link Collection#contains}. Returns {@code false} if the {@code contains} method
    * throws a {@code ClassCastException} or {@code NullPointerException}.
    */
-  static boolean safeContains(Collection<?> collection, @Nullable Object object) {
+  static boolean safeContains(Collection<?> collection, @CheckForNull Object object) {
     checkNotNull(collection);
     try {
       return collection.contains(object);
@@ -113,7 +117,7 @@ static boolean safeContains(Collection<?> collection, @Nullable Object object) {
    * Delegates to {@link Collection#remove}. Returns {@code false} if the {@code remove} method
    * throws a {@code ClassCastException} or {@code NullPointerException}.
    */
-  static boolean safeRemove(Collection<?> collection, @Nullable Object object) {
+  static boolean safeRemove(Collection<?> collection, @CheckForNull Object object) {
     checkNotNull(collection);
     try {
       return collection.remove(object);
@@ -122,7 +126,7 @@ static boolean safeRemove(Collection<?> collection, @Nullable Object object) {
     }
   }
 
-  static class FilteredCollection<E> extends AbstractCollection<E> {
+  static class FilteredCollection<E extends @Nullable Object> extends AbstractCollection<E> {
     final Collection<E> unfiltered;
     final Predicate<? super E> predicate;
 
@@ -137,7 +141,7 @@ FilteredCollection<E> createCombined(Predicate<? super E> newPredicate) {
     }
 
     @Override
-    public boolean add(E element) {
+    public boolean add(@ParametricNullness E element) {
       checkArgument(predicate.apply(element));
       return unfiltered.add(element);
     }
@@ -157,7 +161,7 @@ public void clear() {
 
     @Pure
     @Override
-    public boolean contains(@Nullable Object element) {
+    public boolean contains(@CheckForNull Object element) {
       if (safeContains(unfiltered, element)) {
         @SuppressWarnings("unchecked") // element is in unfiltered, so it must be an E
         E e = (E) element;
@@ -200,7 +204,7 @@ public void forEach(Consumer<? super E> action) {
     }
 
     @Override
-    public boolean remove(@Nullable Object element) {
+    public boolean remove(@CheckForNull Object element) {
       return contains(element) && unfiltered.remove(element);
     }
 
@@ -233,13 +237,14 @@ public int size() {
     }
 
     @Override
-    public Object[] toArray() {
+    public @Nullable Object[] toArray() {
       // creating an ArrayList so filtering happens once
       return Lists.newArrayList(iterator()).toArray();
     }
 
     @Override
-    public <T> T[] toArray(T[] array) {
+    @SuppressWarnings("nullness") // b/192354773 in our checker affects toArray declarations
+    public <T extends @Nullable Object> T[] toArray(T[] array) {
       return Lists.newArrayList(iterator()).toArray(array);
     }
 
@@ -267,12 +272,13 @@ public <T> T[] toArray(T[] array) {
    *
    * <p><b>{@code Stream} equivalent:</b> {@link java.util.stream.Stream#map Stream.map}.
    */
-  public static <F, T> Collection<T> transform(
+  public static <F extends @Nullable Object, T extends @Nullable Object> Collection<T> transform(
       Collection<F> fromCollection, Function<? super F, T> function) {
     return new TransformedCollection<>(fromCollection, function);
   }
 
-  static class TransformedCollection<F, T> extends AbstractCollection<T> {
+  static class TransformedCollection<F extends @Nullable Object, T extends @Nullable Object>
+      extends AbstractCollection<T> {
     final Collection<F> fromCollection;
     final Function<? super F, ? extends T> function;
 
@@ -502,7 +508,7 @@ public Iterator<List<E>> iterator() {
     }
 
     @Override
-    public boolean contains(@Nullable Object obj) {
+    public boolean contains(@CheckForNull Object obj) {
       if (obj instanceof List) {
         List<?> list = (List<?>) obj;
         return isPermutation(inputList, list);
@@ -517,7 +523,7 @@ public String toString() {
   }
 
   private static final class OrderedPermutationIterator<E> extends AbstractIterator<List<E>> {
-    @Nullable List<E> nextPermutation;
+    @CheckForNull List<E> nextPermutation;
     final Comparator<? super E> comparator;
 
     OrderedPermutationIterator(List<E> list, Comparator<? super E> comparator) {
@@ -526,6 +532,7 @@ private static final class OrderedPermutationIterator<E> extends AbstractIterato
     }
 
     @Override
+    @CheckForNull
     protected List<E> computeNext() {
       if (nextPermutation == null) {
         return endOfData();
@@ -541,6 +548,11 @@ void calculateNextPermutation() {
         nextPermutation = null;
         return;
       }
+      /*
+       * requireNonNull is safe because we don't clear nextPermutation until we're done calling this
+       * method.
+       */
+      requireNonNull(nextPermutation);
 
       int l = findNextL(j);
       Collections.swap(nextPermutation, j, l);
@@ -549,6 +561,11 @@ void calculateNextPermutation() {
     }
 
     int findNextJ() {
+      /*
+       * requireNonNull is safe because we don't clear nextPermutation until we're done calling this
+       * method.
+       */
+      requireNonNull(nextPermutation);
       for (int k = nextPermutation.size() - 2; k >= 0; k--) {
         if (comparator.compare(nextPermutation.get(k), nextPermutation.get(k + 1)) < 0) {
           return k;
@@ -558,6 +575,11 @@ int findNextJ() {
     }
 
     int findNextL(int j) {
+      /*
+       * requireNonNull is safe because we don't clear nextPermutation until we're done calling this
+       * method.
+       */
+      requireNonNull(nextPermutation);
       E ak = nextPermutation.get(j);
       for (int l = nextPermutation.size() - 1; l > j; l--) {
         if (comparator.compare(ak, nextPermutation.get(l)) < 0) {
@@ -613,7 +635,7 @@ public Iterator<List<E>> iterator() {
     }
 
     @Override
-    public boolean contains(@Nullable Object obj) {
+    public boolean contains(@CheckForNull Object obj) {
       if (obj instanceof List) {
         List<?> list = (List<?>) obj;
         return isPermutation(inputList, list);
@@ -644,6 +666,7 @@ private static class PermutationIterator<E> extends AbstractIterator<List<E>> {
     }
 
     @Override
+    @CheckForNull
     protected List<E> computeNext() {
       if (j <= 0) {
         return endOfData();
diff --git a/guava/src/com/google/common/collect/CompactHashMap.java b/guava/src/com/google/common/collect/CompactHashMap.java
index e44153aabfec..86359674c09b 100644
--- a/guava/src/com/google/common/collect/CompactHashMap.java
+++ b/guava/src/com/google/common/collect/CompactHashMap.java
@@ -20,6 +20,9 @@
 import static com.google.common.collect.CollectPreconditions.checkRemove;
 import static com.google.common.collect.CompactHashing.UNSET;
 import static com.google.common.collect.Hashing.smearedHash;
+import static com.google.common.collect.NullnessCasts.uncheckedCastNullableTToT;
+import static com.google.common.collect.NullnessCasts.unsafeNull;
+import static java.util.Objects.requireNonNull;
 
 import com.google.common.annotations.GwtIncompatible;
 import com.google.common.annotations.VisibleForTesting;
@@ -47,6 +50,7 @@
 import java.util.function.BiConsumer;
 import java.util.function.BiFunction;
 import java.util.function.Consumer;
+import javax.annotation.CheckForNull;
 import org.checkerframework.checker.nullness.qual.Nullable;
 import org.checkerframework.checker.nullness.qual.PolyNull;
 import org.checkerframework.checker.signedness.qual.PolySigned;
@@ -79,7 +83,9 @@
  * @author Jon Noack
  */
 @GwtIncompatible // not worth using in GWT for now
-class CompactHashMap<K, V> extends AbstractMap<K, V> implements Serializable {
+@ElementTypesAreNonnullByDefault
+class CompactHashMap<K extends @Nullable Object, V extends @Nullable Object>
+    extends AbstractMap<K, V> implements Serializable {
   /*
    * TODO: Make this a drop-in replacement for j.u. versions, actually drop them in, and test the
    * world. Figure out what sort of space-time tradeoff we're actually going to get here with the
@@ -89,7 +95,8 @@ class CompactHashMap<K, V> extends AbstractMap<K, V> implements Serializable {
    */
 
   /** Creates an empty {@code CompactHashMap} instance. */
-  public static <K, V> CompactHashMap<K, V> create() {
+  public static <K extends @Nullable Object, V extends @Nullable Object>
+      CompactHashMap<K, V> create() {
     return new CompactHashMap<>();
   }
 
@@ -102,7 +109,8 @@ public static <K, V> CompactHashMap<K, V> create() {
    *     elements without resizing
    * @throws IllegalArgumentException if {@code expectedSize} is negative
    */
-  public static <K, V> CompactHashMap<K, V> createWithExpectedSize(int expectedSize) {
+  public static <K extends @Nullable Object, V extends @Nullable Object>
+      CompactHashMap<K, V> createWithExpectedSize(int expectedSize) {
     return new CompactHashMap<>(expectedSize);
   }
 
@@ -122,6 +130,46 @@ public static <K, V> CompactHashMap<K, V> createWithExpectedSize(int expectedSiz
    */
   private static final int MAX_HASH_BUCKET_LENGTH = 9;
 
+  // The way the `table`, `entries`, `keys`, and `values` arrays work together is as follows.
+  //
+  // The `table` array always has a size that is a power of 2. The hashcode of a key in the map
+  // is masked in order to correspond to the current table size. For example, if the table size
+  // is 128 then the mask is 127 == 0x7f, keeping the bottom 7 bits of the hash value.
+  // If a key hashes to 0x89abcdef the mask reduces it to 0x89abcdef & 0x7f == 0x6f. We'll call this
+  // the "short hash".
+  //
+  // The `keys`, `values`, and `entries` arrays always have the same size as each other. They can be
+  // seen as fields of an imaginary `Entry` object like this:
+  //
+  // class Entry {
+  //    int hash;
+  //    Entry next;
+  //    K key;
+  //    V value;
+  // }
+  //
+  // The imaginary `hash` and `next` values are combined into a single `int` value in the `entries`
+  // array. The top bits of this value are the remaining bits of the hash value that were not used
+  // in the short hash. We saw that a mask of 0x7f would keep the 7-bit value 0x6f from a full
+  // hashcode of 0x89abcdef. The imaginary `hash` value would then be the remaining top 25 bits,
+  // 0x89abcd80. To this is added (or'd) the `next` value, which is an index within `entries`
+  // (and therefore within `keys` and `values`) of another entry that has the same short hash
+  // value. In our example, it would be another entry for a key whose short hash is also 0x6f.
+  //
+  // Essentially, then, `table[h]` gives us the start of a linked list in `entries`, where every
+  // element of the list has the short hash value h.
+  //
+  // A wrinkle here is that the value 0 (called UNSET in the code) is used as the equivalent of a
+  // null pointer. If `table[h] == 0` that means there are no keys in the map whose short hash is h.
+  // If the `next` bits in `entries[i]` are 0 that means there are no further entries for the given
+  // short hash. But 0 is also a valid index in `entries`, so we add 1 to these indices before
+  // putting them in `table` or in `next` bits, and subtract 1 again when we need an index value.
+  //
+  // The elements of `keys`, `values`, and `entries` are added sequentially, so that elements 0 to
+  // `size() - 1` are used and remaining elements are not. This makes iteration straightforward.
+  // Removing an entry generally involves moving the last element of each array to where the removed
+  // entry was, and adjusting index links accordingly.
+
   /**
    * The hashtable object. This can be either:
    *
@@ -141,7 +189,7 @@ public static <K, V> CompactHashMap<K, V> createWithExpectedSize(int expectedSiz
    *   <li>null, if no entries have yet been added to the map
    * </ul>
    */
-  private transient @Nullable Object table;
+  @CheckForNull private transient Object table;
 
   /**
    * Contains the logical entries, in the range of [0, size()). The high bits of each int are the
@@ -151,32 +199,38 @@ public static <K, V> CompactHashMap<K, V> createWithExpectedSize(int expectedSiz
    *
    * <pre>
    * hash  = aaaaaaaa
-   * mask  = 0000ffff
-   * next  = 0000bbbb
-   * entry = aaaabbbb
+   * mask  = 00000fff
+   * next  = 00000bbb
+   * entry = aaaaabbb
    * </pre>
    *
    * <p>The pointers in [size(), entries.length) are all "null" (UNSET).
    */
-  @VisibleForTesting transient int @Nullable [] entries;
+  @VisibleForTesting @CheckForNull transient int[] entries;
 
   /**
    * The keys of the entries in the map, in the range of [0, size()). The keys in [size(),
    * keys.length) are all {@code null}.
    */
-  @VisibleForTesting transient Object @Nullable [] keys;
+  @VisibleForTesting @CheckForNull transient @Nullable Object[] keys;
 
   /**
    * The values of the entries in the map, in the range of [0, size()). The values in [size(),
    * values.length) are all {@code null}.
    */
-  @VisibleForTesting transient Object @Nullable [] values;
+  @VisibleForTesting @CheckForNull transient @Nullable Object[] values;
 
   /**
    * Keeps track of metadata like the number of hash table bits and modifications of this data
    * structure (to make it possible to throw ConcurrentModificationException in the iterator). Note
    * that we choose not to make this volatile, so we do less of a "best effort" to track such
    * errors, for better performance.
+   *
+   * <p>For a new instance, where the arrays above have not yet been allocated, the value of {@code
+   * metadata} is the size that the arrays should be allocated with. Once the arrays have been
+   * allocated, the value of {@code metadata} combines the number of bits in the "short hash", in
+   * its bottom {@value CompactHashing#HASH_TABLE_BITS_MAX_BITS} bits, with a modification count in
+   * the remaining bits that is used to detect concurrent modification during iteration.
    */
   private transient int metadata;
 
@@ -230,7 +284,7 @@ int allocArrays() {
 
   @SuppressWarnings("unchecked")
   @VisibleForTesting
-  @Nullable
+  @CheckForNull
   Map<K, V> delegateOrNull() {
     if (table instanceof Map) {
       return (Map<K, V>) table;
@@ -242,13 +296,12 @@ Map<K, V> createHashFloodingResistantDelegate(int tableSize) {
     return new LinkedHashMap<>(tableSize, 1.0f);
   }
 
-  @SuppressWarnings("unchecked")
   @VisibleForTesting
   @CanIgnoreReturnValue
   Map<K, V> convertToHashFloodingResistantImplementation() {
     Map<K, V> newDelegate = createHashFloodingResistantDelegate(hashTableMask() + 1);
     for (int i = firstEntryIndex(); i >= 0; i = getSuccessor(i)) {
-      newDelegate.put((K) keys[i], (V) values[i]);
+      newDelegate.put(key(i), value(i));
     }
     this.table = newDelegate;
     this.entries = null;
@@ -284,30 +337,31 @@ void accessEntry(int index) {
 
   @CanIgnoreReturnValue
   @Override
-  public @Nullable V put(@Nullable K key, @Nullable V value) {
+  @CheckForNull
+  public V put(@ParametricNullness K key, @ParametricNullness V value) {
     if (needsAllocArrays()) {
       allocArrays();
     }
-    @Nullable Map<K, V> delegate = delegateOrNull();
+    Map<K, V> delegate = delegateOrNull();
     if (delegate != null) {
       return delegate.put(key, value);
     }
-    int[] entries = this.entries;
-    Object[] keys = this.keys;
-    Object[] values = this.values;
+    int[] entries = requireEntries();
+    @Nullable Object[] keys = requireKeys();
+    @Nullable Object[] values = requireValues();
 
     int newEntryIndex = this.size; // current size, and pointer to the entry to be appended
     int newSize = newEntryIndex + 1;
     int hash = smearedHash(key);
     int mask = hashTableMask();
     int tableIndex = hash & mask;
-    int next = CompactHashing.tableGet(table, tableIndex);
+    int next = CompactHashing.tableGet(requireTable(), tableIndex);
     if (next == UNSET) { // uninitialized bucket
       if (newSize > mask) {
         // Resize and add new entry
         mask = resizeTable(mask, CompactHashing.newCapacity(mask), hash, newEntryIndex);
       } else {
-        CompactHashing.tableSet(table, tableIndex, newEntryIndex + 1);
+        CompactHashing.tableSet(requireTable(), tableIndex, newEntryIndex + 1);
       }
     } else {
       int entryIndex;
@@ -320,7 +374,6 @@ void accessEntry(int index) {
         if (CompactHashing.getHashPrefix(entry, mask) == hashPrefix
             && Objects.equal(key, keys[entryIndex])) {
           @SuppressWarnings("unchecked") // known to be a V
-          @Nullable
           V oldValue = (V) values[entryIndex];
 
           values[entryIndex] = value;
@@ -352,15 +405,16 @@ void accessEntry(int index) {
   /**
    * Creates a fresh entry with the specified object at the specified position in the entry arrays.
    */
-  void insertEntry(int entryIndex, @Nullable K key, @Nullable V value, int hash, int mask) {
-    this.entries[entryIndex] = CompactHashing.maskCombine(hash, UNSET, mask);
-    this.keys[entryIndex] = key;
-    this.values[entryIndex] = value;
+  void insertEntry(
+      int entryIndex, @ParametricNullness K key, @ParametricNullness V value, int hash, int mask) {
+    this.setEntry(entryIndex, CompactHashing.maskCombine(hash, UNSET, mask));
+    this.setKey(entryIndex, key);
+    this.setValue(entryIndex, value);
   }
 
   /** Resizes the entries storage if necessary. */
   private void resizeMeMaybe(int newSize) {
-    int entriesSize = entries.length;
+    int entriesSize = requireEntries().length;
     if (newSize > entriesSize) {
       // 1.5x but round up to nearest odd (this is optimal for memory consumption on Android)
       int newCapacity =
@@ -376,13 +430,13 @@ private void resizeMeMaybe(int newSize) {
    * the current capacity.
    */
   void resizeEntries(int newCapacity) {
-    this.entries = Arrays.copyOf(entries, newCapacity);
-    this.keys = Arrays.copyOf(keys, newCapacity);
-    this.values = Arrays.copyOf(values, newCapacity);
+    this.entries = Arrays.copyOf(requireEntries(), newCapacity);
+    this.keys = Arrays.copyOf(requireKeys(), newCapacity);
+    this.values = Arrays.copyOf(requireValues(), newCapacity);
   }
 
   @CanIgnoreReturnValue
-  private int resizeTable(int mask, int newCapacity, int targetHash, int targetEntryIndex) {
+  private int resizeTable(int oldMask, int newCapacity, int targetHash, int targetEntryIndex) {
     Object newTable = CompactHashing.createTable(newCapacity);
     int newMask = newCapacity - 1;
 
@@ -391,25 +445,35 @@ private int resizeTable(int mask, int newCapacity, int targetHash, int targetEnt
       CompactHashing.tableSet(newTable, targetHash & newMask, targetEntryIndex + 1);
     }
 
-    Object table = this.table;
-    int[] entries = this.entries;
-
-    // Loop over current hashtable
-    for (int tableIndex = 0; tableIndex <= mask; tableIndex++) {
-      int next = CompactHashing.tableGet(table, tableIndex);
-      while (next != UNSET) {
-        int entryIndex = next - 1;
-        int entry = entries[entryIndex];
-
-        // Rebuild hash using entry hashPrefix and tableIndex ("hashSuffix")
-        int hash = CompactHashing.getHashPrefix(entry, mask) | tableIndex;
+    Object oldTable = requireTable();
+    int[] entries = requireEntries();
+
+    // Loop over `oldTable` to construct its replacement, ``newTable`. The entries do not move, so
+    // the `keys` and `values` arrays do not need to change. But because the "short hash" now has a
+    // different number of bits, we must rewrite each element of `entries` so that its contribution
+    // to the full hashcode reflects the change, and so that its `next` link corresponds to the new
+    // linked list of entries with the new short hash.
+    for (int oldTableIndex = 0; oldTableIndex <= oldMask; oldTableIndex++) {
+      int oldNext = CompactHashing.tableGet(oldTable, oldTableIndex);
+      // Each element of `oldTable` is the head of a (possibly empty) linked list of elements in
+      // `entries`. The `oldNext` loop is going to traverse that linked list.
+      // We need to rewrite the `next` link of each of the elements so that it is in the appropriate
+      // linked list starting from `newTable`. In general, each element from the old linked list
+      // belongs to a different linked list from `newTable`. We insert each element in turn at the
+      // head of its appropriate `newTable` linked list.
+      while (oldNext != UNSET) {
+        int entryIndex = oldNext - 1;
+        int oldEntry = entries[entryIndex];
+
+        // Rebuild the full 32-bit hash using entry hashPrefix and oldTableIndex ("hashSuffix").
+        int hash = CompactHashing.getHashPrefix(oldEntry, oldMask) | oldTableIndex;
 
         int newTableIndex = hash & newMask;
         int newNext = CompactHashing.tableGet(newTable, newTableIndex);
-        CompactHashing.tableSet(newTable, newTableIndex, next);
+        CompactHashing.tableSet(newTable, newTableIndex, oldNext);
         entries[entryIndex] = CompactHashing.maskCombine(hash, newNext, newMask);
 
-        next = CompactHashing.getNext(entry, mask);
+        oldNext = CompactHashing.getNext(oldEntry, oldMask);
       }
     }
 
@@ -418,22 +482,22 @@ private int resizeTable(int mask, int newCapacity, int targetHash, int targetEnt
     return newMask;
   }
 
-  private int indexOf(@Nullable Object key) {
+  private int indexOf(@CheckForNull Object key) {
     if (needsAllocArrays()) {
       return -1;
     }
     int hash = smearedHash(key);
     int mask = hashTableMask();
-    int next = CompactHashing.tableGet(table, hash & mask);
+    int next = CompactHashing.tableGet(requireTable(), hash & mask);
     if (next == UNSET) {
       return -1;
     }
     int hashPrefix = CompactHashing.getHashPrefix(hash, mask);
     do {
       int entryIndex = next - 1;
-      int entry = entries[entryIndex];
+      int entry = entry(entryIndex);
       if (CompactHashing.getHashPrefix(entry, mask) == hashPrefix
-          && Objects.equal(key, keys[entryIndex])) {
+          && Objects.equal(key, key(entryIndex))) {
         return entryIndex;
       }
       next = CompactHashing.getNext(entry, mask);
@@ -442,15 +506,15 @@ private int indexOf(@Nullable Object key) {
   }
 
   @Override
-  public boolean containsKey(@Nullable @UnknownSignedness Object key) {
-    @Nullable Map<K, V> delegate = delegateOrNull();
+  public boolean containsKey(@CheckForNull @UnknownSignedness Object key) {
+    Map<K, V> delegate = delegateOrNull();
     return (delegate != null) ? delegate.containsKey(key) : indexOf(key) != -1;
   }
 
-  @SuppressWarnings("unchecked") // known to be a V
   @Override
-  public V get(@Nullable @UnknownSignedness Object key) {
-    @Nullable Map<K, V> delegate = delegateOrNull();
+  @CheckForNull
+  public V get(@CheckForNull @UnknownSignedness Object key) {
+    Map<K, V> delegate = delegateOrNull();
     if (delegate != null) {
       return delegate.get(key);
     }
@@ -459,14 +523,15 @@ public V get(@Nullable @UnknownSignedness Object key) {
       return null;
     }
     accessEntry(index);
-    return (V) values[index];
+    return value(index);
   }
 
   @CanIgnoreReturnValue
   @SuppressWarnings("unchecked") // known to be a V
   @Override
-  public @Nullable V remove(@Nullable @UnknownSignedness Object key) {
-    @Nullable Map<K, V> delegate = delegateOrNull();
+  @CheckForNull
+  public V remove(@CheckForNull @UnknownSignedness Object key) {
+    Map<K, V> delegate = delegateOrNull();
     if (delegate != null) {
       return delegate.remove(key);
     }
@@ -474,19 +539,25 @@ public V get(@Nullable @UnknownSignedness Object key) {
     return (oldValue == NOT_FOUND) ? null : (V) oldValue;
   }
 
-  private @Nullable Object removeHelper(@Nullable Object key) {
+  private @Nullable Object removeHelper(@CheckForNull Object key) {
     if (needsAllocArrays()) {
       return NOT_FOUND;
     }
     int mask = hashTableMask();
     int index =
         CompactHashing.remove(
-            key, /* value= */ null, mask, table, entries, keys, /* values= */ null);
+            key,
+            /* value= */ null,
+            mask,
+            requireTable(),
+            requireEntries(),
+            requireKeys(),
+            /* values= */ null);
     if (index == -1) {
       return NOT_FOUND;
     }
 
-    @Nullable Object oldValue = values[index];
+    Object oldValue = value(index);
 
     moveLastEntry(index, mask);
     size--;
@@ -499,10 +570,14 @@ public V get(@Nullable @UnknownSignedness Object key) {
    * Moves the last entry in the entry array into {@code dstIndex}, and nulls out its old position.
    */
   void moveLastEntry(int dstIndex, int mask) {
+    Object table = requireTable();
+    int[] entries = requireEntries();
+    @Nullable Object[] keys = requireKeys();
+    @Nullable Object[] values = requireValues();
     int srcIndex = size() - 1;
     if (dstIndex < srcIndex) {
       // move last entry to deleted spot
-      @Nullable Object key = keys[srcIndex];
+      Object key = keys[srcIndex];
       keys[dstIndex] = key;
       values[dstIndex] = values[srcIndex];
       keys[srcIndex] = null;
@@ -555,7 +630,7 @@ int adjustAfterRemove(int indexBeforeRemove, @SuppressWarnings("unused") int ind
     return indexBeforeRemove - 1;
   }
 
-  private abstract class Itr<T> implements Iterator<T> {
+  private abstract class Itr<T extends @Nullable Object> implements Iterator<T> {
     int expectedMetadata = metadata;
     int currentIndex = firstEntryIndex();
     int indexToRemove = -1;
@@ -565,9 +640,11 @@ public boolean hasNext() {
       return currentIndex >= 0;
     }
 
+    @ParametricNullness
     abstract T getOutput(int entry);
 
     @Override
+    @ParametricNullness
     public T next() {
       checkForConcurrentModification();
       if (!hasNext()) {
@@ -584,7 +661,7 @@ public void remove() {
       checkForConcurrentModification();
       checkRemove(indexToRemove >= 0);
       incrementExpectedModCount();
-      CompactHashMap.this.remove(keys[indexToRemove]);
+      CompactHashMap.this.remove(key(indexToRemove));
       currentIndex = adjustAfterRemove(currentIndex, indexToRemove);
       indexToRemove = -1;
     }
@@ -600,21 +677,20 @@ private void checkForConcurrentModification() {
     }
   }
 
-  @SuppressWarnings("unchecked") // known to be Ks and Vs
   @Override
   public void replaceAll(BiFunction<? super K, ? super V, ? extends V> function) {
     checkNotNull(function);
-    @Nullable Map<K, V> delegate = delegateOrNull();
+    Map<K, V> delegate = delegateOrNull();
     if (delegate != null) {
       delegate.replaceAll(function);
     } else {
       for (int i = 0; i < size; i++) {
-        values[i] = function.apply((K) keys[i], (V) values[i]);
+        setValue(i, function.apply(key(i), value(i)));
       }
     }
   }
 
-  private transient @Nullable Set<K> keySetView;
+  @CheckForNull private transient Set<K> keySetView;
 
   @Override
   public Set<K> keySet() {
@@ -632,33 +708,36 @@ class KeySetView extends Maps.KeySet<K, V> {
     }
 
     @Override
-    public @PolySigned Object[] toArray(CompactHashMap<@PolySigned K, @PolySigned V>.KeySetView this) {
+    //public @PolySigned Object[] toArray(CompactHashMap<@PolySigned K, @PolySigned V>.KeySetView this) {
+    public @Nullable Object[] toArray() {
       if (needsAllocArrays()) {
         return new Object[0];
       }
-      @Nullable Map<K, V> delegate = delegateOrNull();
+      Map<K, V> delegate = delegateOrNull();
       return (delegate != null)
           ? delegate.keySet().toArray()
-          : ObjectArrays.copyAsObjectArray(keys, 0, size);
+          : ObjectArrays.copyAsObjectArray(requireKeys(), 0, size);
     }
 
     @Override
-    public <T> T[] toArray(T[] a) {
+    @SuppressWarnings("nullness") // b/192354773 in our checker affects toArray declarations
+    public <T extends @Nullable Object> T[] toArray(T[] a) {
       if (needsAllocArrays()) {
         if (a.length > 0) {
-          a[0] = null;
+          @Nullable Object[] unsoundlyCovariantArray = a;
+          unsoundlyCovariantArray[0] = null;
         }
         return a;
       }
-      @Nullable Map<K, V> delegate = delegateOrNull();
+      Map<K, V> delegate = delegateOrNull();
       return (delegate != null)
           ? delegate.keySet().toArray(a)
-          : ObjectArrays.toArrayImpl(keys, 0, size, a);
+          : ObjectArrays.toArrayImpl(requireKeys(), 0, size, a);
     }
 
     @Override
-    public boolean remove(@Nullable Object o) {
-      @Nullable Map<K, V> delegate = delegateOrNull();
+    public boolean remove(@CheckForNull Object o) {
+      Map<K, V> delegate = delegateOrNull();
       return (delegate != null)
           ? delegate.keySet().remove(o)
           : CompactHashMap.this.removeHelper(o) != NOT_FOUND;
@@ -674,56 +753,55 @@ public Spliterator<K> spliterator() {
       if (needsAllocArrays()) {
         return Spliterators.spliterator(new Object[0], Spliterator.DISTINCT | Spliterator.ORDERED);
       }
-      @Nullable Map<K, V> delegate = delegateOrNull();
+      Map<K, V> delegate = delegateOrNull();
       return (delegate != null)
           ? delegate.keySet().spliterator()
-          : Spliterators.spliterator(keys, 0, size, Spliterator.DISTINCT | Spliterator.ORDERED);
+          : Spliterators.spliterator(
+              requireKeys(), 0, size, Spliterator.DISTINCT | Spliterator.ORDERED);
     }
 
-    @SuppressWarnings("unchecked") // known to be Ks
     @Override
     public void forEach(Consumer<? super K> action) {
       checkNotNull(action);
-      @Nullable Map<K, V> delegate = delegateOrNull();
+      Map<K, V> delegate = delegateOrNull();
       if (delegate != null) {
         delegate.keySet().forEach(action);
       } else {
         for (int i = firstEntryIndex(); i >= 0; i = getSuccessor(i)) {
-          action.accept((K) keys[i]);
+          action.accept(key(i));
         }
       }
     }
   }
 
   Iterator<K> keySetIterator() {
-    @Nullable Map<K, V> delegate = delegateOrNull();
+    Map<K, V> delegate = delegateOrNull();
     if (delegate != null) {
       return delegate.keySet().iterator();
     }
     return new Itr<K>() {
-      @SuppressWarnings("unchecked") // known to be a K
       @Override
+      @ParametricNullness
       K getOutput(int entry) {
-        return (K) keys[entry];
+        return key(entry);
       }
     };
   }
 
-  @SuppressWarnings("unchecked") // known to be Ks and Vs
   @Override
   public void forEach(BiConsumer<? super K, ? super V> action) {
     checkNotNull(action);
-    @Nullable Map<K, V> delegate = delegateOrNull();
+    Map<K, V> delegate = delegateOrNull();
     if (delegate != null) {
       delegate.forEach(action);
     } else {
       for (int i = firstEntryIndex(); i >= 0; i = getSuccessor(i)) {
-        action.accept((K) keys[i], (V) values[i]);
+        action.accept(key(i), value(i));
       }
     }
   }
 
-  private transient @Nullable Set<Entry<K, V>> entrySetView;
+  @CheckForNull private transient Set<Entry<K, V>> entrySetView;
 
   @Override
   public Set<Entry<K, V>> entrySet() {
@@ -748,7 +826,7 @@ public Iterator<Entry<K, V>> iterator() {
 
     @Override
     public Spliterator<Entry<K, V>> spliterator() {
-      @Nullable Map<K, V> delegate = delegateOrNull();
+      Map<K, V> delegate = delegateOrNull();
       return (delegate != null)
           ? delegate.entrySet().spliterator()
           : CollectSpliterators.indexed(
@@ -756,21 +834,21 @@ public Spliterator<Entry<K, V>> spliterator() {
     }
 
     @Override
-    public boolean contains(@Nullable Object o) {
-      @Nullable Map<K, V> delegate = delegateOrNull();
+    public boolean contains(@CheckForNull Object o) {
+      Map<K, V> delegate = delegateOrNull();
       if (delegate != null) {
         return delegate.entrySet().contains(o);
       } else if (o instanceof Entry) {
         Entry<?, ?> entry = (Entry<?, ?>) o;
         int index = indexOf(entry.getKey());
-        return index != -1 && Objects.equal(values[index], entry.getValue());
+        return index != -1 && Objects.equal(value(index), entry.getValue());
       }
       return false;
     }
 
     @Override
-    public boolean remove(@Nullable Object o) {
-      @Nullable Map<K, V> delegate = delegateOrNull();
+    public boolean remove(@CheckForNull Object o) {
+      Map<K, V> delegate = delegateOrNull();
       if (delegate != null) {
         return delegate.entrySet().remove(o);
       } else if (o instanceof Entry) {
@@ -781,7 +859,13 @@ public boolean remove(@Nullable Object o) {
         int mask = hashTableMask();
         int index =
             CompactHashing.remove(
-                entry.getKey(), entry.getValue(), mask, table, entries, keys, values);
+                entry.getKey(),
+                entry.getValue(),
+                mask,
+                requireTable(),
+                requireEntries(),
+                requireKeys(),
+                requireValues());
         if (index == -1) {
           return false;
         }
@@ -797,7 +881,7 @@ public boolean remove(@Nullable Object o) {
   }
 
   Iterator<Entry<K, V>> entrySetIterator() {
-    @Nullable Map<K, V> delegate = delegateOrNull();
+    Map<K, V> delegate = delegateOrNull();
     if (delegate != null) {
       return delegate.entrySet().iterator();
     }
@@ -810,54 +894,66 @@ Entry<K, V> getOutput(int entry) {
   }
 
   final class MapEntry extends AbstractMapEntry<K, V> {
-    private final @Nullable K key;
+    @ParametricNullness private final K key;
 
     private int lastKnownIndex;
 
-    @SuppressWarnings("unchecked") // known to be a K
     MapEntry(int index) {
-      this.key = (K) keys[index];
+      this.key = key(index);
       this.lastKnownIndex = index;
     }
 
     @Override
-    public @Nullable K getKey() {
+    @ParametricNullness
+    public K getKey() {
       return key;
     }
 
     private void updateLastKnownIndex() {
       if (lastKnownIndex == -1
           || lastKnownIndex >= size()
-          || !Objects.equal(key, keys[lastKnownIndex])) {
+          || !Objects.equal(key, key(lastKnownIndex))) {
         lastKnownIndex = indexOf(key);
       }
     }
 
-    @SuppressWarnings("unchecked") // known to be a V
     @Override
-    public @Nullable V getValue() {
-      @Nullable Map<K, V> delegate = delegateOrNull();
+    @ParametricNullness
+    public V getValue() {
+      Map<K, V> delegate = delegateOrNull();
       if (delegate != null) {
-        return delegate.get(key);
+        /*
+         * The cast is safe because the entry is present in the map. Or, if it has been removed by a
+         * concurrent modification, behavior is undefined.
+         */
+        return uncheckedCastNullableTToT(delegate.get(key));
       }
       updateLastKnownIndex();
-      return (lastKnownIndex == -1) ? null : (V) values[lastKnownIndex];
+      /*
+       * If the entry has been removed from the map, we return null, even though that might not be a
+       * valid value. That's the best we can do, short of holding a reference to the most recently
+       * seen value. And while we *could* do that, we aren't required to: Map.Entry explicitly says
+       * that behavior is undefined when the backing map is modified through another API. (It even
+       * permits us to throw IllegalStateException. Maybe we should have done that, but we probably
+       * shouldn't change now for fear of breaking people.)
+       */
+      return (lastKnownIndex == -1) ? unsafeNull() : value(lastKnownIndex);
     }
 
-    @SuppressWarnings("unchecked") // known to be a V
     @Override
-    public V setValue(V value) {
-      @Nullable Map<K, V> delegate = delegateOrNull();
+    @ParametricNullness
+    public V setValue(@ParametricNullness V value) {
+      Map<K, V> delegate = delegateOrNull();
       if (delegate != null) {
-        return delegate.put(key, value);
+        return uncheckedCastNullableTToT(delegate.put(key, value)); // See discussion in getValue().
       }
       updateLastKnownIndex();
       if (lastKnownIndex == -1) {
         put(key, value);
-        return null;
+        return unsafeNull(); // See discussion in getValue().
       } else {
-        V old = (V) values[lastKnownIndex];
-        values[lastKnownIndex] = value;
+        V old = value(lastKnownIndex);
+        CompactHashMap.this.setValue(lastKnownIndex, value);
         return old;
       }
     }
@@ -865,7 +961,7 @@ public V setValue(V value) {
 
   @Override
   public int size() {
-    @Nullable Map<K, V> delegate = delegateOrNull();
+    Map<K, V> delegate = delegateOrNull();
     return (delegate != null) ? delegate.size() : size;
   }
 
@@ -875,20 +971,20 @@ public boolean isEmpty() {
   }
 
   @Override
-  public boolean containsValue(@Nullable Object value) {
-    @Nullable Map<K, V> delegate = delegateOrNull();
+  public boolean containsValue(@CheckForNull Object value) {
+    Map<K, V> delegate = delegateOrNull();
     if (delegate != null) {
       return delegate.containsValue(value);
     }
     for (int i = 0; i < size; i++) {
-      if (Objects.equal(value, values[i])) {
+      if (Objects.equal(value, value(i))) {
         return true;
       }
     }
     return false;
   }
 
-  private transient @Nullable Collection<V> valuesView;
+  @CheckForNull private transient Collection<V> valuesView;
 
   @Override
   public Collection<V> values() {
@@ -910,16 +1006,15 @@ public Iterator<V> iterator() {
       return valuesIterator();
     }
 
-    @SuppressWarnings("unchecked") // known to be Vs
     @Override
     public void forEach(Consumer<? super V> action) {
       checkNotNull(action);
-      @Nullable Map<K, V> delegate = delegateOrNull();
+      Map<K, V> delegate = delegateOrNull();
       if (delegate != null) {
         delegate.values().forEach(action);
       } else {
         for (int i = firstEntryIndex(); i >= 0; i = getSuccessor(i)) {
-          action.accept((V) values[i]);
+          action.accept(value(i));
         }
       }
     }
@@ -929,48 +1024,50 @@ public Spliterator<V> spliterator() {
       if (needsAllocArrays()) {
         return Spliterators.spliterator(new Object[0], Spliterator.ORDERED);
       }
-      @Nullable Map<K, V> delegate = delegateOrNull();
+      Map<K, V> delegate = delegateOrNull();
       return (delegate != null)
           ? delegate.values().spliterator()
-          : Spliterators.spliterator(values, 0, size, Spliterator.ORDERED);
+          : Spliterators.spliterator(requireValues(), 0, size, Spliterator.ORDERED);
     }
 
     @Override
-    public Object[] toArray() {
+    public @Nullable Object[] toArray() {
       if (needsAllocArrays()) {
         return new Object[0];
       }
-      @Nullable Map<K, V> delegate = delegateOrNull();
+      Map<K, V> delegate = delegateOrNull();
       return (delegate != null)
           ? delegate.values().toArray()
-          : ObjectArrays.copyAsObjectArray(values, 0, size);
+          : ObjectArrays.copyAsObjectArray(requireValues(), 0, size);
     }
 
     @Override
-    public <T> T[] toArray(T[] a) {
+    @SuppressWarnings("nullness") // b/192354773 in our checker affects toArray declarations
+    public <T extends @Nullable Object> T[] toArray(T[] a) {
       if (needsAllocArrays()) {
         if (a.length > 0) {
-          a[0] = null;
+          @Nullable Object[] unsoundlyCovariantArray = a;
+          unsoundlyCovariantArray[0] = null;
         }
         return a;
       }
-      @Nullable Map<K, V> delegate = delegateOrNull();
+      Map<K, V> delegate = delegateOrNull();
       return (delegate != null)
           ? delegate.values().toArray(a)
-          : ObjectArrays.toArrayImpl(values, 0, size, a);
+          : ObjectArrays.toArrayImpl(requireValues(), 0, size, a);
     }
   }
 
   Iterator<V> valuesIterator() {
-    @Nullable Map<K, V> delegate = delegateOrNull();
+    Map<K, V> delegate = delegateOrNull();
     if (delegate != null) {
       return delegate.values().iterator();
     }
     return new Itr<V>() {
-      @SuppressWarnings("unchecked") // known to be a V
       @Override
+      @ParametricNullness
       V getOutput(int entry) {
-        return (V) values[entry];
+        return value(entry);
       }
     };
   }
@@ -983,7 +1080,7 @@ public void trimToSize() {
     if (needsAllocArrays()) {
       return;
     }
-    @Nullable Map<K, V> delegate = delegateOrNull();
+    Map<K, V> delegate = delegateOrNull();
     if (delegate != null) {
       Map<K, V> newDelegate = createHashFloodingResistantDelegate(size());
       newDelegate.putAll(delegate);
@@ -991,7 +1088,7 @@ public void trimToSize() {
       return;
     }
     int size = this.size;
-    if (size < entries.length) {
+    if (size < requireEntries().length) {
       resizeEntries(size);
     }
     int minimumTableSize = CompactHashing.tableSize(size);
@@ -1007,7 +1104,7 @@ public void clear() {
       return;
     }
     incrementModCount();
-    @Nullable Map<K, V> delegate = delegateOrNull();
+    Map<K, V> delegate = delegateOrNull();
     if (delegate != null) {
       metadata =
           Ints.constrainToRange(size(), CompactHashing.DEFAULT_SIZE, CompactHashing.MAX_SIZE);
@@ -1015,10 +1112,10 @@ public void clear() {
       table = null;
       size = 0;
     } else {
-      Arrays.fill(keys, 0, size, null);
-      Arrays.fill(values, 0, size, null);
-      CompactHashing.tableClear(table);
-      Arrays.fill(entries, 0, size, 0);
+      Arrays.fill(requireKeys(), 0, size, null);
+      Arrays.fill(requireValues(), 0, size, null);
+      CompactHashing.tableClear(requireTable());
+      Arrays.fill(requireEntries(), 0, size, 0);
       this.size = 0;
     }
   }
@@ -1048,4 +1145,66 @@ private void readObject(ObjectInputStream stream) throws IOException, ClassNotFo
       put(key, value);
     }
   }
+
+  /*
+   * The following methods are safe to call as long as both of the following hold:
+   *
+   * - allocArrays() has been called. Callers can confirm this by checking needsAllocArrays().
+   *
+   * - The map has not switched to delegating to a java.util implementation to mitigate hash
+   *   flooding. Callers can confirm this by null-checking delegateOrNull().
+   *
+   * In an ideal world, we would document why we know those things are true every time we call these
+   * methods. But that is a bit too painful....
+   */
+
+  private Object requireTable() {
+    return requireNonNull(table);
+  }
+
+  private int[] requireEntries() {
+    return requireNonNull(entries);
+  }
+
+  private @Nullable Object[] requireKeys() {
+    return requireNonNull(keys);
+  }
+
+  private @Nullable Object[] requireValues() {
+    return requireNonNull(values);
+  }
+
+  /*
+   * The following methods are safe to call as long as the conditions in the *previous* comment are
+   * met *and* the index is less than size().
+   *
+   * (The above explains when these methods are safe from a `nullness` perspective. From an
+   * `unchecked` perspective, they're safe because we put only K/V elements into each array.)
+   */
+
+  @SuppressWarnings("unchecked")
+  private K key(int i) {
+    return (K) requireKeys()[i];
+  }
+
+  @SuppressWarnings("unchecked")
+  private V value(int i) {
+    return (V) requireValues()[i];
+  }
+
+  private int entry(int i) {
+    return requireEntries()[i];
+  }
+
+  private void setKey(int i, K key) {
+    requireKeys()[i] = key;
+  }
+
+  private void setValue(int i, V value) {
+    requireValues()[i] = value;
+  }
+
+  private void setEntry(int i, int value) {
+    requireEntries()[i] = value;
+  }
 }
diff --git a/guava/src/com/google/common/collect/CompactHashSet.java b/guava/src/com/google/common/collect/CompactHashSet.java
index d344da6597c4..88f62adf7b2c 100644
--- a/guava/src/com/google/common/collect/CompactHashSet.java
+++ b/guava/src/com/google/common/collect/CompactHashSet.java
@@ -20,6 +20,7 @@
 import static com.google.common.collect.CollectPreconditions.checkRemove;
 import static com.google.common.collect.CompactHashing.UNSET;
 import static com.google.common.collect.Hashing.smearedHash;
+import static java.util.Objects.requireNonNull;
 
 import com.google.common.annotations.GwtIncompatible;
 import com.google.common.annotations.VisibleForTesting;
@@ -44,6 +45,7 @@
 import java.util.Spliterator;
 import java.util.Spliterators;
 import java.util.function.Consumer;
+import javax.annotation.CheckForNull;
 import org.checkerframework.checker.nullness.qual.Nullable;
 import org.checkerframework.checker.signedness.qual.PolySigned;
 import org.checkerframework.checker.signedness.qual.UnknownSignedness;
@@ -76,11 +78,12 @@
  * @author Jon Noack
  */
 @GwtIncompatible // not worth using in GWT for now
-class CompactHashSet<E> extends AbstractSet<E> implements Serializable {
+@ElementTypesAreNonnullByDefault
+class CompactHashSet<E extends @Nullable Object> extends AbstractSet<E> implements Serializable {
   // TODO(user): cache all field accesses in local vars
 
   /** Creates an empty {@code CompactHashSet} instance. */
-  public static <E> CompactHashSet<E> create() {
+  public static <E extends @Nullable Object> CompactHashSet<E> create() {
     return new CompactHashSet<>();
   }
 
@@ -91,7 +94,8 @@ public static <E> CompactHashSet<E> create() {
    * @param collection the elements that the set should contain
    * @return a new {@code CompactHashSet} containing those elements (minus duplicates)
    */
-  public static <E> CompactHashSet<E> create(Collection<? extends E> collection) {
+  public static <E extends @Nullable Object> CompactHashSet<E> create(
+      Collection<? extends E> collection) {
     CompactHashSet<E> set = createWithExpectedSize(collection.size());
     set.addAll(collection);
     return set;
@@ -105,7 +109,7 @@ public static <E> CompactHashSet<E> create(Collection<? extends E> collection) {
    * @return a new {@code CompactHashSet} containing those elements (minus duplicates)
    */
   @SafeVarargs
-  public static <E> CompactHashSet<E> create(E... elements) {
+  public static <E extends @Nullable Object> CompactHashSet<E> create(E... elements) {
     CompactHashSet<E> set = createWithExpectedSize(elements.length);
     Collections.addAll(set, elements);
     return set;
@@ -120,7 +124,8 @@ public static <E> CompactHashSet<E> create(E... elements) {
    *     elements without resizing
    * @throws IllegalArgumentException if {@code expectedSize} is negative
    */
-  public static <E> CompactHashSet<E> createWithExpectedSize(int expectedSize) {
+  public static <E extends @Nullable Object> CompactHashSet<E> createWithExpectedSize(
+      int expectedSize) {
     return new CompactHashSet<>(expectedSize);
   }
 
@@ -138,6 +143,10 @@ public static <E> CompactHashSet<E> createWithExpectedSize(int expectedSize) {
    */
   private static final int MAX_HASH_BUCKET_LENGTH = 9;
 
+  // See CompactHashMap for a detailed description of how the following fields work. That
+  // description talks about `keys`, `values`, and `entries`; here the `keys` and `values` arrays
+  // are replaced by a single `elements` array but everything else works similarly.
+
   /**
    * The hashtable object. This can be either:
    *
@@ -157,7 +166,7 @@ public static <E> CompactHashSet<E> createWithExpectedSize(int expectedSize) {
    *   <li>null, if no entries have yet been added to the map
    * </ul>
    */
-  private transient @Nullable Object table;
+  @CheckForNull private transient Object table;
 
   /**
    * Contains the logical entries, in the range of [0, size()). The high bits of each int are the
@@ -167,20 +176,20 @@ public static <E> CompactHashSet<E> createWithExpectedSize(int expectedSize) {
    *
    * <pre>
    * hash  = aaaaaaaa
-   * mask  = 0000ffff
-   * next  = 0000bbbb
-   * entry = aaaabbbb
+   * mask  = 00000fff
+   * next  = 00000bbb
+   * entry = aaaaabbb
    * </pre>
    *
    * <p>The pointers in [size(), entries.length) are all "null" (UNSET).
    */
-  private transient int @Nullable [] entries;
+  @CheckForNull private transient int[] entries;
 
   /**
    * The elements contained in the set, in the range of [0, size()). The elements in [size(),
    * elements.length) are all {@code null}.
    */
-  @VisibleForTesting transient Object @Nullable [] elements;
+  @VisibleForTesting @CheckForNull transient @Nullable Object[] elements;
 
   /**
    * Keeps track of metadata like the number of hash table bits and modifications of this data
@@ -239,7 +248,7 @@ int allocArrays() {
 
   @SuppressWarnings("unchecked")
   @VisibleForTesting
-  @Nullable
+  @CheckForNull
   Set<E> delegateOrNull() {
     if (table instanceof Set) {
       return (Set<E>) table;
@@ -251,13 +260,12 @@ private Set<E> createHashFloodingResistantDelegate(int tableSize) {
     return new LinkedHashSet<>(tableSize, 1.0f);
   }
 
-  @SuppressWarnings("unchecked")
   @VisibleForTesting
   @CanIgnoreReturnValue
   Set<E> convertToHashFloodingResistantImplementation() {
     Set<E> newDelegate = createHashFloodingResistantDelegate(hashTableMask() + 1);
     for (int i = firstEntryIndex(); i >= 0; i = getSuccessor(i)) {
-      newDelegate.add((E) elements[i]);
+      newDelegate.add(element(i));
     }
     this.table = newDelegate;
     this.entries = null;
@@ -289,30 +297,29 @@ void incrementModCount() {
 
   @CanIgnoreReturnValue
   @Override
-  public boolean add(@Nullable E object) {
+  public boolean add(@ParametricNullness E object) {
     if (needsAllocArrays()) {
       allocArrays();
     }
-    @Nullable Set<E> delegate = delegateOrNull();
+    Set<E> delegate = delegateOrNull();
     if (delegate != null) {
       return delegate.add(object);
     }
-    int[] entries = this.entries;
-    Object[] elements = this.elements;
+    int[] entries = requireEntries();
+    @Nullable Object[] elements = requireElements();
 
     int newEntryIndex = this.size; // current size, and pointer to the entry to be appended
     int newSize = newEntryIndex + 1;
-    @SuppressWarnings("signedness:argument")
     int hash = smearedHash(object);
     int mask = hashTableMask();
     int tableIndex = hash & mask;
-    int next = CompactHashing.tableGet(table, tableIndex);
+    int next = CompactHashing.tableGet(requireTable(), tableIndex);
     if (next == UNSET) { // uninitialized bucket
       if (newSize > mask) {
         // Resize and add new entry
         mask = resizeTable(mask, CompactHashing.newCapacity(mask), hash, newEntryIndex);
       } else {
-        CompactHashing.tableSet(table, tableIndex, newEntryIndex + 1);
+        CompactHashing.tableSet(requireTable(), tableIndex, newEntryIndex + 1);
       }
     } else {
       int entryIndex;
@@ -351,15 +358,14 @@ public boolean add(@Nullable E object) {
   /**
    * Creates a fresh entry with the specified object at the specified position in the entry arrays.
    */
-  @SuppressWarnings("signedness:assignment")
-  void insertEntry(int entryIndex, @Nullable E object, int hash, int mask) {
-    this.entries[entryIndex] = CompactHashing.maskCombine(hash, UNSET, mask);
-    this.elements[entryIndex] = object;
+  void insertEntry(int entryIndex, @ParametricNullness E object, int hash, int mask) {
+    setEntry(entryIndex, CompactHashing.maskCombine(hash, UNSET, mask));
+    setElement(entryIndex, object);
   }
 
   /** Resizes the entries storage if necessary. */
   private void resizeMeMaybe(int newSize) {
-    int entriesSize = entries.length;
+    int entriesSize = requireEntries().length;
     if (newSize > entriesSize) {
       // 1.5x but round up to nearest odd (this is optimal for memory consumption on Android)
       int newCapacity =
@@ -375,12 +381,12 @@ private void resizeMeMaybe(int newSize) {
    * the current capacity.
    */
   void resizeEntries(int newCapacity) {
-    this.entries = Arrays.copyOf(entries, newCapacity);
-    this.elements = Arrays.copyOf(elements, newCapacity);
+    this.entries = Arrays.copyOf(requireEntries(), newCapacity);
+    this.elements = Arrays.copyOf(requireElements(), newCapacity);
   }
 
   @CanIgnoreReturnValue
-  private int resizeTable(int mask, int newCapacity, int targetHash, int targetEntryIndex) {
+  private int resizeTable(int oldMask, int newCapacity, int targetHash, int targetEntryIndex) {
     Object newTable = CompactHashing.createTable(newCapacity);
     int newMask = newCapacity - 1;
 
@@ -389,25 +395,25 @@ private int resizeTable(int mask, int newCapacity, int targetHash, int targetEnt
       CompactHashing.tableSet(newTable, targetHash & newMask, targetEntryIndex + 1);
     }
 
-    Object table = this.table;
-    int[] entries = this.entries;
+    Object oldTable = requireTable();
+    int[] entries = requireEntries();
 
     // Loop over current hashtable
-    for (int tableIndex = 0; tableIndex <= mask; tableIndex++) {
-      int next = CompactHashing.tableGet(table, tableIndex);
-      while (next != UNSET) {
-        int entryIndex = next - 1;
-        int entry = entries[entryIndex];
+    for (int oldTableIndex = 0; oldTableIndex <= oldMask; oldTableIndex++) {
+      int oldNext = CompactHashing.tableGet(oldTable, oldTableIndex);
+      while (oldNext != UNSET) {
+        int entryIndex = oldNext - 1;
+        int oldEntry = entries[entryIndex];
 
         // Rebuild hash using entry hashPrefix and tableIndex ("hashSuffix")
-        int hash = CompactHashing.getHashPrefix(entry, mask) | tableIndex;
+        int hash = CompactHashing.getHashPrefix(oldEntry, oldMask) | oldTableIndex;
 
         int newTableIndex = hash & newMask;
         int newNext = CompactHashing.tableGet(newTable, newTableIndex);
-        CompactHashing.tableSet(newTable, newTableIndex, next);
+        CompactHashing.tableSet(newTable, newTableIndex, oldNext);
         entries[entryIndex] = CompactHashing.maskCombine(hash, newNext, newMask);
 
-        next = CompactHashing.getNext(entry, mask);
+        oldNext = CompactHashing.getNext(oldEntry, oldMask);
       }
     }
 
@@ -417,26 +423,26 @@ private int resizeTable(int mask, int newCapacity, int targetHash, int targetEnt
   }
 
   @Override
-  public boolean contains(@Nullable @UnknownSignedness Object object) {
+  public boolean contains(@CheckForNull @UnknownSignedness Object object) {
     if (needsAllocArrays()) {
       return false;
     }
-    @Nullable Set<E> delegate = delegateOrNull();
+    Set<E> delegate = delegateOrNull();
     if (delegate != null) {
       return delegate.contains(object);
     }
     int hash = smearedHash(object);
     int mask = hashTableMask();
-    int next = CompactHashing.tableGet(table, hash & mask);
+    int next = CompactHashing.tableGet(requireTable(), hash & mask);
     if (next == UNSET) {
       return false;
     }
     int hashPrefix = CompactHashing.getHashPrefix(hash, mask);
     do {
       int entryIndex = next - 1;
-      int entry = entries[entryIndex];
+      int entry = entry(entryIndex);
       if (CompactHashing.getHashPrefix(entry, mask) == hashPrefix
-          && Objects.equal(object, elements[entryIndex])) {
+          && Objects.equal(object, element(entryIndex))) {
         return true;
       }
       next = CompactHashing.getNext(entry, mask);
@@ -446,18 +452,24 @@ public boolean contains(@Nullable @UnknownSignedness Object object) {
 
   @CanIgnoreReturnValue
   @Override
-  public boolean remove(@Nullable @UnknownSignedness Object object) {
+  public boolean remove(@CheckForNull @UnknownSignedness Object object) {
     if (needsAllocArrays()) {
       return false;
     }
-    @Nullable Set<E> delegate = delegateOrNull();
+    Set<E> delegate = delegateOrNull();
     if (delegate != null) {
       return delegate.remove(object);
     }
     int mask = hashTableMask();
     int index =
         CompactHashing.remove(
-            object, /* value= */ null, mask, table, entries, elements, /* values= */ null);
+            object,
+            /* value= */ null,
+            mask,
+            requireTable(),
+            requireEntries(),
+            requireElements(),
+            /* values= */ null);
     if (index == -1) {
       return false;
     }
@@ -473,10 +485,13 @@ public boolean remove(@Nullable @UnknownSignedness Object object) {
    * Moves the last entry in the entry array into {@code dstIndex}, and nulls out its old position.
    */
   void moveLastEntry(int dstIndex, int mask) {
+    Object table = requireTable();
+    int[] entries = requireEntries();
+    @Nullable Object[] elements = requireElements();
     int srcIndex = size() - 1;
     if (dstIndex < srcIndex) {
       // move last entry to deleted spot
-      @Nullable Object object = elements[srcIndex];
+      Object object = elements[srcIndex];
       elements[dstIndex] = object;
       elements[srcIndex] = null;
 
@@ -528,7 +543,7 @@ int adjustAfterRemove(int indexBeforeRemove, @SuppressWarnings("unused") int ind
 
   @Override
   public Iterator<E> iterator() {
-    @Nullable Set<E> delegate = delegateOrNull();
+    Set<E> delegate = delegateOrNull();
     if (delegate != null) {
       return delegate.iterator();
     }
@@ -542,15 +557,15 @@ public boolean hasNext() {
         return currentIndex >= 0;
       }
 
-      @SuppressWarnings("unchecked") // known to be Es
       @Override
+      @ParametricNullness
       public E next() {
         checkForConcurrentModification();
         if (!hasNext()) {
           throw new NoSuchElementException();
         }
         indexToRemove = currentIndex;
-        E result = (E) elements[currentIndex];
+        E result = element(currentIndex);
         currentIndex = getSuccessor(currentIndex);
         return result;
       }
@@ -560,7 +575,7 @@ public void remove() {
         checkForConcurrentModification();
         checkRemove(indexToRemove >= 0);
         incrementExpectedModCount();
-        CompactHashSet.this.remove(elements[indexToRemove]);
+        CompactHashSet.this.remove(element(indexToRemove));
         currentIndex = adjustAfterRemove(currentIndex, indexToRemove);
         indexToRemove = -1;
       }
@@ -582,29 +597,29 @@ public Spliterator<E> spliterator() {
     if (needsAllocArrays()) {
       return Spliterators.spliterator(new Object[0], Spliterator.DISTINCT | Spliterator.ORDERED);
     }
-    @Nullable Set<E> delegate = delegateOrNull();
+    Set<E> delegate = delegateOrNull();
     return (delegate != null)
         ? delegate.spliterator()
-        : Spliterators.spliterator(elements, 0, size, Spliterator.DISTINCT | Spliterator.ORDERED);
+        : Spliterators.spliterator(
+            requireElements(), 0, size, Spliterator.DISTINCT | Spliterator.ORDERED);
   }
 
-  @SuppressWarnings("unchecked") // known to be Es
   @Override
   public void forEach(Consumer<? super E> action) {
     checkNotNull(action);
-    @Nullable Set<E> delegate = delegateOrNull();
+    Set<E> delegate = delegateOrNull();
     if (delegate != null) {
       delegate.forEach(action);
     } else {
       for (int i = firstEntryIndex(); i >= 0; i = getSuccessor(i)) {
-        action.accept((E) elements[i]);
+        action.accept(element(i));
       }
     }
   }
 
   @Override
   public int size() {
-    @Nullable Set<E> delegate = delegateOrNull();
+    Set<E> delegate = delegateOrNull();
     return (delegate != null) ? delegate.size() : size;
   }
 
@@ -614,27 +629,29 @@ public boolean isEmpty() {
   }
 
   @Override
-  public @PolySigned Object[] toArray(CompactHashSet<@PolySigned E> this) {
+  //public @PolySigned Object[] toArray(CompactHashSet<@PolySigned E> this) {
+  public @Nullable Object[] toArray() {
     if (needsAllocArrays()) {
       return new Object[0];
     }
-    @Nullable Set<E> delegate = delegateOrNull();
-    return (delegate != null) ? delegate.toArray() : Arrays.copyOf(elements, size);
+    Set<E> delegate = delegateOrNull();
+    return (delegate != null) ? delegate.toArray() : Arrays.copyOf(requireElements(), size);
   }
 
   @CanIgnoreReturnValue
   @Override
-  public <T> T[] toArray(T[] a) {
+  @SuppressWarnings("nullness") // b/192354773 in our checker affects toArray declarations
+  public <T extends @Nullable Object> T[] toArray(T[] a) {
     if (needsAllocArrays()) {
       if (a.length > 0) {
         a[0] = null;
       }
       return a;
     }
-    @Nullable Set<E> delegate = delegateOrNull();
+    Set<E> delegate = delegateOrNull();
     return (delegate != null)
         ? delegate.toArray(a)
-        : ObjectArrays.toArrayImpl(elements, 0, size, a);
+        : ObjectArrays.toArrayImpl(requireElements(), 0, size, a);
   }
 
   /**
@@ -645,7 +662,7 @@ public void trimToSize() {
     if (needsAllocArrays()) {
       return;
     }
-    @Nullable Set<E> delegate = delegateOrNull();
+    Set<E> delegate = delegateOrNull();
     if (delegate != null) {
       Set<E> newDelegate = createHashFloodingResistantDelegate(size());
       newDelegate.addAll(delegate);
@@ -653,7 +670,7 @@ public void trimToSize() {
       return;
     }
     int size = this.size;
-    if (size < entries.length) {
+    if (size < requireEntries().length) {
       resizeEntries(size);
     }
     int minimumTableSize = CompactHashing.tableSize(size);
@@ -670,7 +687,7 @@ public void clear() {
       return;
     }
     incrementModCount();
-    @Nullable Set<E> delegate = delegateOrNull();
+    Set<E> delegate = delegateOrNull();
     if (delegate != null) {
       metadata =
           Ints.constrainToRange(size(), CompactHashing.DEFAULT_SIZE, CompactHashing.MAX_SIZE);
@@ -678,14 +695,13 @@ public void clear() {
       table = null;
       size = 0;
     } else {
-      Arrays.fill(elements, 0, size, null);
-      CompactHashing.tableClear(table);
-      Arrays.fill(entries, 0, size, 0);
+      Arrays.fill(requireElements(), 0, size, null);
+      CompactHashing.tableClear(requireTable());
+      Arrays.fill(requireEntries(), 0, size, 0);
       this.size = 0;
     }
   }
 
-  @SuppressWarnings("signedness:argument")
   private void writeObject(ObjectOutputStream stream) throws IOException {
     stream.defaultWriteObject();
     stream.writeInt(size());
@@ -707,4 +723,38 @@ private void readObject(ObjectInputStream stream) throws IOException, ClassNotFo
       add(element);
     }
   }
+
+  /*
+   * For discussion of the safety of the following methods, see the comments near the end of
+   * CompactHashMap.
+   */
+
+  private Object requireTable() {
+    return requireNonNull(table);
+  }
+
+  private int[] requireEntries() {
+    return requireNonNull(entries);
+  }
+
+  private @Nullable Object[] requireElements() {
+    return requireNonNull(elements);
+  }
+
+  @SuppressWarnings("unchecked")
+  private E element(int i) {
+    return (E) requireElements()[i];
+  }
+
+  private int entry(int i) {
+    return requireEntries()[i];
+  }
+
+  private void setElement(int i, E value) {
+    requireElements()[i] = value;
+  }
+
+  private void setEntry(int i, int value) {
+    requireEntries()[i] = value;
+  }
 }
diff --git a/guava/src/com/google/common/collect/CompactHashing.java b/guava/src/com/google/common/collect/CompactHashing.java
index 3444aeb84198..a8fe90214c78 100644
--- a/guava/src/com/google/common/collect/CompactHashing.java
+++ b/guava/src/com/google/common/collect/CompactHashing.java
@@ -20,6 +20,7 @@
 import com.google.common.base.Objects;
 import com.google.common.primitives.Ints;
 import java.util.Arrays;
+import javax.annotation.CheckForNull;
 import org.checkerframework.checker.nullness.qual.Nullable;
 
 /**
@@ -28,6 +29,7 @@
  * @author Jon Noack
  */
 @GwtIncompatible
+@ElementTypesAreNonnullByDefault
 final class CompactHashing {
   private CompactHashing() {}
 
@@ -96,6 +98,11 @@ static void tableClear(Object table) {
     }
   }
 
+  /**
+   * Returns {@code table[index]}, where {@code table} is actually a {@code byte[]}, {@code
+   * short[]}, or {@code int[]}. When it is a {@code byte[]} or {@code short[]}, the returned value
+   * is unsigned, so the range of possible returned values is 0–255 or 0–65535, respectively.
+   */
   static int tableGet(Object table, int index) {
     if (table instanceof byte[]) {
       return ((byte[]) table)[index] & BYTE_MASK; // unsigned read
@@ -106,6 +113,13 @@ static int tableGet(Object table, int index) {
     }
   }
 
+  /**
+   * Sets {@code table[index]} to {@code entry}, where {@code table} is actually a {@code byte[]},
+   * {@code short[]}, or {@code int[]}. The value of {@code entry} should fit in the size of the
+   * assigned array element, when seen as an unsigned value. So if {@code table} is a {@code byte[]}
+   * then we should have {@code 0 ≤ entry ≤ 255}, and if {@code table} is a {@code short[]} then we
+   * should have {@code 0 ≤ entry ≤ 65535}. It is the caller's responsibility to ensure this.
+   */
   static void tableSet(Object table, int index, int entry) {
     if (table instanceof byte[]) {
       ((byte[]) table)[index] = (byte) entry; // unsigned write
@@ -143,13 +157,13 @@ static int maskCombine(int prefix, int suffix, int mask) {
   }
 
   static int remove(
-      @Nullable Object key,
-      @Nullable Object value,
+      @CheckForNull Object key,
+      @CheckForNull Object value,
       int mask,
       Object table,
       int[] entries,
-      Object[] keys,
-      Object @Nullable [] values) {
+      @Nullable Object[] keys,
+      @CheckForNull @Nullable Object[] values) {
     int hash = Hashing.smearedHash(key);
     int tableIndex = hash & mask;
     int next = tableGet(table, tableIndex);
diff --git a/guava/src/com/google/common/collect/CompactLinkedHashMap.java b/guava/src/com/google/common/collect/CompactLinkedHashMap.java
index be878c86a144..97b3a4b1c3b9 100644
--- a/guava/src/com/google/common/collect/CompactLinkedHashMap.java
+++ b/guava/src/com/google/common/collect/CompactLinkedHashMap.java
@@ -16,6 +16,8 @@
 
 package com.google.common.collect;
 
+import static java.util.Objects.requireNonNull;
+
 import com.google.common.annotations.GwtIncompatible;
 import com.google.common.annotations.VisibleForTesting;
 import com.google.errorprone.annotations.CanIgnoreReturnValue;
@@ -27,6 +29,7 @@
 import java.util.Set;
 import java.util.Spliterator;
 import java.util.Spliterators;
+import javax.annotation.CheckForNull;
 import org.checkerframework.checker.nullness.qual.Nullable;
 
 /**
@@ -50,11 +53,14 @@
  * @author Louis Wasserman
  */
 @GwtIncompatible // not worth using in GWT for now
-class CompactLinkedHashMap<K, V> extends CompactHashMap<K, V> {
+@ElementTypesAreNonnullByDefault
+class CompactLinkedHashMap<K extends @Nullable Object, V extends @Nullable Object>
+    extends CompactHashMap<K, V> {
   // TODO(lowasser): implement removeEldestEntry so this can be used as a drop-in replacement
 
   /** Creates an empty {@code CompactLinkedHashMap} instance. */
-  public static <K, V> CompactLinkedHashMap<K, V> create() {
+  public static <K extends @Nullable Object, V extends @Nullable Object>
+      CompactLinkedHashMap<K, V> create() {
     return new CompactLinkedHashMap<>();
   }
 
@@ -67,7 +73,8 @@ public static <K, V> CompactLinkedHashMap<K, V> create() {
    *     expectedSize} elements without resizing
    * @throws IllegalArgumentException if {@code expectedSize} is negative
    */
-  public static <K, V> CompactLinkedHashMap<K, V> createWithExpectedSize(int expectedSize) {
+  public static <K extends @Nullable Object, V extends @Nullable Object>
+      CompactLinkedHashMap<K, V> createWithExpectedSize(int expectedSize) {
     return new CompactLinkedHashMap<>(expectedSize);
   }
 
@@ -82,7 +89,7 @@ public static <K, V> CompactLinkedHashMap<K, V> createWithExpectedSize(int expec
    * <p>A node with "prev" pointer equal to {@code ENDPOINT} is the first node in the linked list,
    * and a node with "next" pointer equal to {@code ENDPOINT} is the last node.
    */
-  @VisibleForTesting transient long @Nullable [] links;
+  @CheckForNull @VisibleForTesting transient long[] links;
 
   /** Pointer to the first node in the linked list, or {@code ENDPOINT} if there are no entries. */
   private transient int firstEntry;
@@ -132,23 +139,29 @@ Map<K, V> convertToHashFloodingResistantImplementation() {
     return result;
   }
 
+  /*
+   * For discussion of the safety of the following methods for operating on predecessors and
+   * successors, see the comments near the end of CompactHashMap, noting that the methods here call
+   * link(), which is defined at the end of this file.
+   */
+
   private int getPredecessor(int entry) {
-    return ((int) (links[entry] >>> 32)) - 1;
+    return ((int) (link(entry) >>> 32)) - 1;
   }
 
   @Override
   int getSuccessor(int entry) {
-    return ((int) links[entry]) - 1;
+    return ((int) link(entry)) - 1;
   }
 
   private void setSuccessor(int entry, int succ) {
     long succMask = (~0L) >>> 32;
-    links[entry] = (links[entry] & ~succMask) | ((succ + 1) & succMask);
+    setLink(entry, (link(entry) & ~succMask) | ((succ + 1) & succMask));
   }
 
   private void setPredecessor(int entry, int pred) {
     long predMask = ~0L << 32;
-    links[entry] = (links[entry] & ~predMask) | ((long) (pred + 1) << 32);
+    setLink(entry, (link(entry) & ~predMask) | ((long) (pred + 1) << 32));
   }
 
   private void setSucceeds(int pred, int succ) {
@@ -166,7 +179,8 @@ private void setSucceeds(int pred, int succ) {
   }
 
   @Override
-  void insertEntry(int entryIndex, @Nullable K key, @Nullable V value, int hash, int mask) {
+  void insertEntry(
+      int entryIndex, @ParametricNullness K key, @ParametricNullness V value, int hash, int mask) {
     super.insertEntry(entryIndex, key, value, hash, mask);
     setSucceeds(lastEntry, entryIndex);
     setSucceeds(entryIndex, ENDPOINT);
@@ -194,13 +208,13 @@ void moveLastEntry(int dstIndex, int mask) {
       setSucceeds(getPredecessor(srcIndex), dstIndex);
       setSucceeds(dstIndex, getSuccessor(srcIndex));
     }
-    links[srcIndex] = 0;
+    setLink(srcIndex, 0);
   }
 
   @Override
   void resizeEntries(int newCapacity) {
     super.resizeEntries(newCapacity);
-    links = Arrays.copyOf(links, newCapacity);
+    links = Arrays.copyOf(requireLinks(), newCapacity);
   }
 
   @Override
@@ -230,12 +244,13 @@ Set<K> createKeySet() {
     @WeakOuter
     class KeySetImpl extends KeySetView {
       @Override
-      public Object[] toArray() {
+      public @Nullable Object[] toArray() {
         return ObjectArrays.toArrayImpl(this);
       }
 
       @Override
-      public <T> T[] toArray(T[] a) {
+      @SuppressWarnings("nullness") // b/192354773 in our checker affects toArray declarations
+      public <T extends @Nullable Object> T[] toArray(T[] a) {
         return ObjectArrays.toArrayImpl(this, a);
       }
 
@@ -252,12 +267,13 @@ Collection<V> createValues() {
     @WeakOuter
     class ValuesImpl extends ValuesView {
       @Override
-      public Object[] toArray() {
+      public @Nullable Object[] toArray() {
         return ObjectArrays.toArrayImpl(this);
       }
 
       @Override
-      public <T> T[] toArray(T[] a) {
+      @SuppressWarnings("nullness") // b/192354773 in our checker affects toArray declarations
+      public <T extends @Nullable Object> T[] toArray(T[] a) {
         return ObjectArrays.toArrayImpl(this, a);
       }
 
@@ -281,4 +297,27 @@ public void clear() {
     }
     super.clear();
   }
+
+  /*
+   * For discussion of the safety of the following methods, see the comments near the end of
+   * CompactHashMap.
+   */
+
+  private long[] requireLinks() {
+    return requireNonNull(links);
+  }
+
+  private long link(int i) {
+    return requireLinks()[i];
+  }
+
+  private void setLink(int i, long value) {
+    requireLinks()[i] = value;
+  }
+
+  /*
+   * We don't define getPredecessor+getSuccessor and setPredecessor+setSuccessor here because
+   * they're defined above -- including logic to add and subtract 1 to map between the values stored
+   * in the predecessor/successor arrays and the indexes in the elements array that they identify.
+   */
 }
diff --git a/guava/src/com/google/common/collect/CompactLinkedHashSet.java b/guava/src/com/google/common/collect/CompactLinkedHashSet.java
index 74caf47e367b..c1d813cdb435 100644
--- a/guava/src/com/google/common/collect/CompactLinkedHashSet.java
+++ b/guava/src/com/google/common/collect/CompactLinkedHashSet.java
@@ -16,6 +16,8 @@
 
 package com.google.common.collect;
 
+import static java.util.Objects.requireNonNull;
+
 import com.google.common.annotations.GwtIncompatible;
 import com.google.errorprone.annotations.CanIgnoreReturnValue;
 import java.util.Arrays;
@@ -24,6 +26,7 @@
 import java.util.Set;
 import java.util.Spliterator;
 import java.util.Spliterators;
+import javax.annotation.CheckForNull;
 import org.checkerframework.checker.nullness.qual.Nullable;
 
 /**
@@ -48,10 +51,11 @@
  * @author Louis Wasserman
  */
 @GwtIncompatible // not worth using in GWT for now
-class CompactLinkedHashSet<E> extends CompactHashSet<E> {
+@ElementTypesAreNonnullByDefault
+class CompactLinkedHashSet<E extends @Nullable Object> extends CompactHashSet<E> {
 
   /** Creates an empty {@code CompactLinkedHashSet} instance. */
-  public static <E> CompactLinkedHashSet<E> create() {
+  public static <E extends @Nullable Object> CompactLinkedHashSet<E> create() {
     return new CompactLinkedHashSet<>();
   }
 
@@ -62,7 +66,8 @@ public static <E> CompactLinkedHashSet<E> create() {
    * @param collection the elements that the set should contain
    * @return a new {@code CompactLinkedHashSet} containing those elements (minus duplicates)
    */
-  public static <E> CompactLinkedHashSet<E> create(Collection<? extends E> collection) {
+  public static <E extends @Nullable Object> CompactLinkedHashSet<E> create(
+      Collection<? extends E> collection) {
     CompactLinkedHashSet<E> set = createWithExpectedSize(collection.size());
     set.addAll(collection);
     return set;
@@ -76,7 +81,7 @@ public static <E> CompactLinkedHashSet<E> create(Collection<? extends E> collect
    * @return a new {@code CompactLinkedHashSet} containing those elements (minus duplicates)
    */
   @SafeVarargs
-  public static <E> CompactLinkedHashSet<E> create(E... elements) {
+  public static <E extends @Nullable Object> CompactLinkedHashSet<E> create(E... elements) {
     CompactLinkedHashSet<E> set = createWithExpectedSize(elements.length);
     Collections.addAll(set, elements);
     return set;
@@ -91,7 +96,8 @@ public static <E> CompactLinkedHashSet<E> create(E... elements) {
    *     expectedSize} elements without resizing
    * @throws IllegalArgumentException if {@code expectedSize} is negative
    */
-  public static <E> CompactLinkedHashSet<E> createWithExpectedSize(int expectedSize) {
+  public static <E extends @Nullable Object> CompactLinkedHashSet<E> createWithExpectedSize(
+      int expectedSize) {
     return new CompactLinkedHashSet<>(expectedSize);
   }
 
@@ -105,13 +111,13 @@ public static <E> CompactLinkedHashSet<E> createWithExpectedSize(int expectedSiz
    * Pointer to the predecessor of an entry in insertion order. ENDPOINT indicates a node is the
    * first node in insertion order; all values at indices ≥ {@link #size()} are UNSET.
    */
-  private transient int @Nullable [] predecessor;
+  @CheckForNull private transient int[] predecessor;
 
   /**
    * Pointer to the successor of an entry in insertion order. ENDPOINT indicates a node is the last
    * node in insertion order; all values at indices ≥ {@link #size()} are UNSET.
    */
-  private transient int @Nullable [] successor;
+  @CheckForNull private transient int[] successor;
 
   /** Pointer to the first node in the linked list, or {@code ENDPOINT} if there are no entries. */
   private transient int firstEntry;
@@ -151,21 +157,27 @@ Set<E> convertToHashFloodingResistantImplementation() {
     return result;
   }
 
+  /*
+   * For discussion of the safety of the following methods for operating on predecessors and
+   * successors, see the comments near the end of CompactHashMap, noting that the methods here call
+   * requirePredecessors() and requireSuccessors(), which are defined at the end of this file.
+   */
+
   private int getPredecessor(int entry) {
-    return predecessor[entry] - 1;
+    return requirePredecessors()[entry] - 1;
   }
 
   @Override
   int getSuccessor(int entry) {
-    return successor[entry] - 1;
+    return requireSuccessors()[entry] - 1;
   }
 
   private void setSuccessor(int entry, int succ) {
-    successor[entry] = succ + 1;
+    requireSuccessors()[entry] = succ + 1;
   }
 
   private void setPredecessor(int entry, int pred) {
-    predecessor[entry] = pred + 1;
+    requirePredecessors()[entry] = pred + 1;
   }
 
   private void setSucceeds(int pred, int succ) {
@@ -183,7 +195,7 @@ private void setSucceeds(int pred, int succ) {
   }
 
   @Override
-  void insertEntry(int entryIndex, @Nullable E object, int hash, int mask) {
+  void insertEntry(int entryIndex, @ParametricNullness E object, int hash, int mask) {
     super.insertEntry(entryIndex, object, hash, mask);
     setSucceeds(lastEntry, entryIndex);
     setSucceeds(entryIndex, ENDPOINT);
@@ -199,15 +211,15 @@ void moveLastEntry(int dstIndex, int mask) {
       setSucceeds(getPredecessor(srcIndex), dstIndex);
       setSucceeds(dstIndex, getSuccessor(srcIndex));
     }
-    predecessor[srcIndex] = 0;
-    successor[srcIndex] = 0;
+    requirePredecessors()[srcIndex] = 0;
+    requireSuccessors()[srcIndex] = 0;
   }
 
   @Override
   void resizeEntries(int newCapacity) {
     super.resizeEntries(newCapacity);
-    predecessor = Arrays.copyOf(predecessor, newCapacity);
-    successor = Arrays.copyOf(successor, newCapacity);
+    predecessor = Arrays.copyOf(requirePredecessors(), newCapacity);
+    successor = Arrays.copyOf(requireSuccessors(), newCapacity);
   }
 
   @Override
@@ -221,12 +233,13 @@ int adjustAfterRemove(int indexBeforeRemove, int indexRemoved) {
   }
 
   @Override
-  public Object[] toArray() {
+  public @Nullable Object[] toArray() {
     return ObjectArrays.toArrayImpl(this);
   }
 
   @Override
-  public <T> T[] toArray(T[] a) {
+  @SuppressWarnings("nullness") // b/192354773 in our checker affects toArray declarations
+  public <T extends @Nullable Object> T[] toArray(T[] a) {
     return ObjectArrays.toArrayImpl(this, a);
   }
 
@@ -242,10 +255,30 @@ public void clear() {
     }
     this.firstEntry = ENDPOINT;
     this.lastEntry = ENDPOINT;
-    if (predecessor != null) {
+    // Either both arrays are null or neither is, but we check both to satisfy the nullness checker.
+    if (predecessor != null && successor != null) {
       Arrays.fill(predecessor, 0, size(), 0);
       Arrays.fill(successor, 0, size(), 0);
     }
     super.clear();
   }
+
+  /*
+   * For discussion of the safety of the following methods, see the comments near the end of
+   * CompactHashMap.
+   */
+
+  private int[] requirePredecessors() {
+    return requireNonNull(predecessor);
+  }
+
+  private int[] requireSuccessors() {
+    return requireNonNull(successor);
+  }
+
+  /*
+   * We don't define getPredecessor+getSuccessor and setPredecessor+setSuccessor here because
+   * they're defined above -- including logic to add and subtract 1 to map between the values stored
+   * in the predecessor/successor arrays and the indexes in the elements array that they identify.
+   */
 }
diff --git a/guava/src/com/google/common/collect/ComparatorOrdering.java b/guava/src/com/google/common/collect/ComparatorOrdering.java
index 7e937f799760..e021ddb90fec 100644
--- a/guava/src/com/google/common/collect/ComparatorOrdering.java
+++ b/guava/src/com/google/common/collect/ComparatorOrdering.java
@@ -21,6 +21,7 @@
 import com.google.common.annotations.GwtCompatible;
 import java.io.Serializable;
 import java.util.Comparator;
+import javax.annotation.CheckForNull;
 import org.checkerframework.checker.nullness.qual.Nullable;
 import org.checkerframework.dataflow.qual.Pure;
 import org.checkerframework.framework.qual.AnnotatedFor;
@@ -28,7 +29,9 @@
 /** An ordering for a pre-existing comparator. */
 @AnnotatedFor({"nullness"})
 @GwtCompatible(serializable = true)
-final class ComparatorOrdering<T> extends Ordering<T> implements Serializable {
+@ElementTypesAreNonnullByDefault
+final class ComparatorOrdering<T extends @Nullable Object> extends Ordering<T>
+    implements Serializable {
   final Comparator<T> comparator;
 
   ComparatorOrdering(Comparator<T> comparator) {
@@ -37,13 +40,13 @@ final class ComparatorOrdering<T> extends Ordering<T> implements Serializable {
 
   @Pure
   @Override
-  public int compare(T a, T b) {
+  public int compare(@ParametricNullness T a, @ParametricNullness T b) {
     return comparator.compare(a, b);
   }
 
   @Pure
   @Override
-  public boolean equals(@Nullable Object object) {
+  public boolean equals(@CheckForNull Object object) {
     if (object == this) {
       return true;
     }
diff --git a/guava/src/com/google/common/collect/Comparators.java b/guava/src/com/google/common/collect/Comparators.java
index a541de95f15b..5779be31bfaf 100644
--- a/guava/src/com/google/common/collect/Comparators.java
+++ b/guava/src/com/google/common/collect/Comparators.java
@@ -19,7 +19,6 @@
 import static com.google.common.base.Preconditions.checkNotNull;
 import static com.google.common.collect.CollectPreconditions.checkNonnegative;
 
-import com.google.common.annotations.Beta;
 import com.google.common.annotations.GwtCompatible;
 import java.util.Comparator;
 import java.util.Iterator;
@@ -44,6 +43,7 @@
  * @author Louis Wasserman
  */
 @GwtCompatible
+@ElementTypesAreNonnullByDefault
 public final class Comparators {
   private Comparators() {}
 
@@ -61,8 +61,8 @@ private Comparators() {}
   // Note: 90% of the time we don't add type parameters or wildcards that serve only to "tweak" the
   // desired return type. However, *nested* generics introduce a special class of problems that we
   // think tip it over into being worthwhile.
-  @Beta
-  public static <T, S extends T> Comparator<Iterable<S>> lexicographical(Comparator<T> comparator) {
+  public static <T extends @Nullable Object, S extends T> Comparator<Iterable<S>> lexicographical(
+      Comparator<T> comparator) {
     return new LexicographicalOrdering<S>(checkNotNull(comparator));
   }
 
@@ -71,8 +71,8 @@ public static <T, S extends T> Comparator<Iterable<S>> lexicographical(Comparato
    * equal to the element that preceded it, according to the specified comparator. Note that this is
    * always true when the iterable has fewer than two elements.
    */
-  @Beta
-  public static <T> boolean isInOrder(Iterable<? extends T> iterable, Comparator<T> comparator) {
+  public static <T extends @Nullable Object> boolean isInOrder(
+      Iterable<? extends T> iterable, Comparator<T> comparator) {
     checkNotNull(comparator);
     Iterator<? extends T> it = iterable.iterator();
     if (it.hasNext()) {
@@ -93,8 +93,7 @@ public static <T> boolean isInOrder(Iterable<? extends T> iterable, Comparator<T
    * greater than the element that preceded it, according to the specified comparator. Note that
    * this is always true when the iterable has fewer than two elements.
    */
-  @Beta
-  public static <T> boolean isInStrictOrder(
+  public static <T extends @Nullable Object> boolean isInStrictOrder(
       Iterable<? extends T> iterable, Comparator<T> comparator) {
     checkNotNull(comparator);
     Iterator<? extends T> it = iterable.iterator();
@@ -131,7 +130,8 @@ public static <T> boolean isInStrictOrder(
    * @throws IllegalArgumentException if {@code k < 0}
    * @since 22.0
    */
-  public static <T> Collector<T, ?, List<T>> least(int k, Comparator<? super T> comparator) {
+  public static <T extends @Nullable Object> Collector<T, ?, List<T>> least(
+      int k, Comparator<? super T> comparator) {
     checkNonnegative(k, "k");
     checkNotNull(comparator);
     return Collector.of(
@@ -162,7 +162,8 @@ public static <T> boolean isInStrictOrder(
    * @throws IllegalArgumentException if {@code k < 0}
    * @since 22.0
    */
-  public static <T> Collector<T, ?, List<T>> greatest(int k, Comparator<? super T> comparator) {
+  public static <T extends @Nullable Object> Collector<T, ?, List<T>> greatest(
+      int k, Comparator<? super T> comparator) {
     return least(k, comparator.reversed());
   }
 
@@ -173,10 +174,10 @@ public static <T> boolean isInStrictOrder(
    *
    * @since 22.0
    */
-  @Beta
   public static <T> Comparator<Optional<T>> emptiesFirst(Comparator<? super T> valueComparator) {
     checkNotNull(valueComparator);
-    return Comparator.comparing(o -> o.orElse(null), Comparator.nullsFirst(valueComparator));
+    return Comparator.<Optional<T>, @Nullable T>comparing(
+        o -> o.orElse(null), Comparator.nullsFirst(valueComparator));
   }
 
   /**
@@ -186,10 +187,10 @@ public static <T> Comparator<Optional<T>> emptiesFirst(Comparator<? super T> val
    *
    * @since 22.0
    */
-  @Beta
   public static <T> Comparator<Optional<T>> emptiesLast(Comparator<? super T> valueComparator) {
     checkNotNull(valueComparator);
-    return Comparator.comparing(o -> o.orElse(null), Comparator.nullsLast(valueComparator));
+    return Comparator.<Optional<T>, @Nullable T>comparing(
+        o -> o.orElse(null), Comparator.nullsLast(valueComparator));
   }
 
   /**
@@ -205,7 +206,6 @@ public static <T> Comparator<Optional<T>> emptiesLast(Comparator<? super T> valu
    * @throws ClassCastException if the parameters are not <i>mutually comparable</i>.
    * @since 30.0
    */
-  @Beta
   public static <T extends Comparable<? super T>> T min(T a, T b) {
     return (a.compareTo(b) <= 0) ? a : b;
   }
@@ -225,8 +225,9 @@ public static <T extends Comparable<? super T>> T min(T a, T b) {
    *     comparator.
    * @since 30.0
    */
-  @Beta
-  public static <T> T min(@Nullable T a, @Nullable T b, Comparator<T> comparator) {
+  @ParametricNullness
+  public static <T extends @Nullable Object> T min(
+      @ParametricNullness T a, @ParametricNullness T b, Comparator<T> comparator) {
     return (comparator.compare(a, b) <= 0) ? a : b;
   }
 
@@ -243,7 +244,6 @@ public static <T> T min(@Nullable T a, @Nullable T b, Comparator<T> comparator)
    * @throws ClassCastException if the parameters are not <i>mutually comparable</i>.
    * @since 30.0
    */
-  @Beta
   public static <T extends Comparable<? super T>> T max(T a, T b) {
     return (a.compareTo(b) >= 0) ? a : b;
   }
@@ -263,8 +263,9 @@ public static <T extends Comparable<? super T>> T max(T a, T b) {
    *     comparator.
    * @since 30.0
    */
-  @Beta
-  public static <T> T max(@Nullable T a, @Nullable T b, Comparator<T> comparator) {
+  @ParametricNullness
+  public static <T extends @Nullable Object> T max(
+      @ParametricNullness T a, @ParametricNullness T b, Comparator<T> comparator) {
     return (comparator.compare(a, b) >= 0) ? a : b;
   }
 }
diff --git a/guava/src/com/google/common/collect/ComparisonChain.java b/guava/src/com/google/common/collect/ComparisonChain.java
index 578166de0e93..9c05205ec01d 100644
--- a/guava/src/com/google/common/collect/ComparisonChain.java
+++ b/guava/src/com/google/common/collect/ComparisonChain.java
@@ -49,7 +49,7 @@
  * the presence of expensive {@code compareTo} and {@code compare} implementations.
  *
  * <p>See the Guava User Guide article on <a href=
- * "https://github.com/google/guava/wiki/CommonObjectUtilitiesExplained#comparecompareto"> {@code
+ * "https://github.com/google/guava/wiki/CommonObjectUtilitiesExplained#comparecompareto">{@code
  * ComparisonChain}</a>.
  *
  * @author Mark Davis
@@ -57,6 +57,7 @@
  * @since 2.0
  */
 @GwtCompatible
+@ElementTypesAreNonnullByDefault
 public abstract class ComparisonChain {
   private ComparisonChain() {}
 
@@ -67,15 +68,15 @@ public static ComparisonChain start() {
 
   private static final ComparisonChain ACTIVE =
       new ComparisonChain() {
-        @SuppressWarnings("unchecked")
+        @SuppressWarnings("unchecked") // unsafe; see discussion on supertype
         @Override
-        public ComparisonChain compare(Comparable left, Comparable right) {
-          return classify(left.compareTo(right));
+        public ComparisonChain compare(Comparable<?> left, Comparable<?> right) {
+          return classify(((Comparable<Object>) left).compareTo(right));
         }
 
         @Override
-        public <T> ComparisonChain compare(
-            @Nullable T left, @Nullable T right, Comparator<T> comparator) {
+        public <T extends @Nullable Object> ComparisonChain compare(
+            @ParametricNullness T left, @ParametricNullness T right, Comparator<T> comparator) {
           return classify(comparator.compare(left, right));
         }
 
@@ -131,13 +132,13 @@ private static final class InactiveComparisonChain extends ComparisonChain {
     }
 
     @Override
-    public ComparisonChain compare(@Nullable Comparable left, @Nullable Comparable right) {
+    public ComparisonChain compare(Comparable<?> left, Comparable<?> right) {
       return this;
     }
 
     @Override
-    public <T> ComparisonChain compare(
-        @Nullable T left, @Nullable T right, @Nullable Comparator<T> comparator) {
+    public <T extends @Nullable Object> ComparisonChain compare(
+        @ParametricNullness T left, @ParametricNullness T right, Comparator<T> comparator) {
       return this;
     }
 
@@ -180,6 +181,18 @@ public int result() {
   /**
    * Compares two comparable objects as specified by {@link Comparable#compareTo}, <i>if</i> the
    * result of this comparison chain has not already been determined.
+   *
+   * <p>This method is declared to accept any 2 {@code Comparable} objects, even if they are not <a
+   * href="https://docs.oracle.com/javase/tutorial/collections/interfaces/order.html">mutually
+   * comparable</a>. If you pass objects that are not mutually comparable, this method may throw an
+   * exception. (The reason for this decision is lost to time, but the reason <i>might</i> be that
+   * we wanted to support legacy classes that implement the raw type {@code Comparable} (instead of
+   * implementing {@code Comparable<Foo>}) without producing warnings. If so, we would prefer today
+   * to produce warnings in that case, and we may change this method to do so in the future. Support
+   * for raw {@code Comparable} types in Guava in general is tracked as <a
+   * href="https://github.com/google/guava/issues/989">#989</a>.)
+   *
+   * @throws ClassCastException if the parameters are not mutually comparable
    */
   public abstract ComparisonChain compare(Comparable<?> left, Comparable<?> right);
 
@@ -187,8 +200,8 @@ public int result() {
    * Compares two objects using a comparator, <i>if</i> the result of this comparison chain has not
    * already been determined.
    */
-  public abstract <T> ComparisonChain compare(
-      @Nullable T left, @Nullable T right, Comparator<T> comparator);
+  public abstract <T extends @Nullable Object> ComparisonChain compare(
+      @ParametricNullness T left, @ParametricNullness T right, Comparator<T> comparator);
 
   /**
    * Compares two {@code int} values as specified by {@link Ints#compare}, <i>if</i> the result of
diff --git a/guava/src/com/google/common/collect/CompoundOrdering.java b/guava/src/com/google/common/collect/CompoundOrdering.java
index da6df42299c4..e8732b015ee5 100644
--- a/guava/src/com/google/common/collect/CompoundOrdering.java
+++ b/guava/src/com/google/common/collect/CompoundOrdering.java
@@ -20,6 +20,7 @@
 import java.io.Serializable;
 import java.util.Arrays;
 import java.util.Comparator;
+import javax.annotation.CheckForNull;
 import org.checkerframework.checker.nullness.qual.Nullable;
 import org.checkerframework.dataflow.qual.Pure;
 import org.checkerframework.framework.qual.AnnotatedFor;
@@ -27,7 +28,9 @@
 /** An ordering that tries several comparators in order. */
 @AnnotatedFor({"nullness"})
 @GwtCompatible(serializable = true)
-final class CompoundOrdering<T> extends Ordering<T> implements Serializable {
+@ElementTypesAreNonnullByDefault
+final class CompoundOrdering<T extends @Nullable Object> extends Ordering<T>
+    implements Serializable {
   final Comparator<? super T>[] comparators;
 
   CompoundOrdering(Comparator<? super T> primary, Comparator<? super T> secondary) {
@@ -40,7 +43,7 @@ final class CompoundOrdering<T> extends Ordering<T> implements Serializable {
 
   @Pure
   @Override
-  public int compare(T left, T right) {
+  public int compare(@ParametricNullness T left, @ParametricNullness T right) {
     for (int i = 0; i < comparators.length; i++) {
       int result = comparators[i].compare(left, right);
       if (result != 0) {
@@ -52,7 +55,7 @@ public int compare(T left, T right) {
 
   @Pure
   @Override
-  public boolean equals(@Nullable Object object) {
+  public boolean equals(@CheckForNull Object object) {
     if (object == this) {
       return true;
     }
diff --git a/guava/src/com/google/common/collect/ComputationException.java b/guava/src/com/google/common/collect/ComputationException.java
index 86647d93df6c..1e0cc9ff100c 100644
--- a/guava/src/com/google/common/collect/ComputationException.java
+++ b/guava/src/com/google/common/collect/ComputationException.java
@@ -17,6 +17,7 @@
 package com.google.common.collect;
 
 import com.google.common.annotations.GwtCompatible;
+import javax.annotation.CheckForNull;
 import org.checkerframework.checker.nullness.qual.Nullable;
 import org.checkerframework.framework.qual.AnnotatedFor;
 
@@ -36,9 +37,10 @@
 @AnnotatedFor({"nullness"})
 @Deprecated
 @GwtCompatible
+@ElementTypesAreNonnullByDefault
 public class ComputationException extends RuntimeException {
   /** Creates a new instance with the given cause. */
-  public ComputationException(@Nullable Throwable cause) {
+  public ComputationException(@CheckForNull Throwable cause) {
     super(cause);
   }
 
diff --git a/guava/src/com/google/common/collect/ConcurrentHashMultiset.java b/guava/src/com/google/common/collect/ConcurrentHashMultiset.java
index 927ffb6dd581..05db19689fb5 100644
--- a/guava/src/com/google/common/collect/ConcurrentHashMultiset.java
+++ b/guava/src/com/google/common/collect/ConcurrentHashMultiset.java
@@ -18,8 +18,8 @@
 
 import static com.google.common.base.Preconditions.checkArgument;
 import static com.google.common.base.Preconditions.checkNotNull;
+import static com.google.common.base.Preconditions.checkState;
 import static com.google.common.collect.CollectPreconditions.checkNonnegative;
-import static com.google.common.collect.CollectPreconditions.checkRemove;
 
 import com.google.common.annotations.Beta;
 import com.google.common.annotations.GwtIncompatible;
@@ -41,6 +41,7 @@
 import java.util.concurrent.ConcurrentHashMap;
 import java.util.concurrent.ConcurrentMap;
 import java.util.concurrent.atomic.AtomicInteger;
+import javax.annotation.CheckForNull;
 import org.checkerframework.checker.nullness.qual.Nullable;
 import org.checkerframework.dataflow.qual.Pure;
 import org.checkerframework.dataflow.qual.SideEffectFree;
@@ -51,8 +52,7 @@
  * {@code Multiset} operations (exceptions where noted). Null elements are not supported.
  *
  * <p>See the Guava User Guide article on <a href=
- * "https://github.com/google/guava/wiki/NewCollectionTypesExplained#multiset"> {@code
- * Multiset}</a>.
+ * "https://github.com/google/guava/wiki/NewCollectionTypesExplained#multiset">{@code Multiset}</a>.
  *
  * @author Cliff L. Biffle
  * @author mike nonemacher
@@ -60,6 +60,7 @@
  */
 @AnnotatedFor({"nullness"})
 @GwtIncompatible
+@ElementTypesAreNonnullByDefault
 public final class ConcurrentHashMultiset<E> extends AbstractMultiset<E> implements Serializable {
 
   /*
@@ -90,7 +91,7 @@ public static <E> ConcurrentHashMultiset<E> create() {
     // TODO(schmoe): provide a way to use this class with other (possibly arbitrary)
     // ConcurrentMap implementors. One possibility is to extract most of this class into
     // an AbstractConcurrentMapMultiset.
-    return new ConcurrentHashMultiset<E>(new ConcurrentHashMap<E, AtomicInteger>());
+    return new ConcurrentHashMultiset<>(new ConcurrentHashMap<E, AtomicInteger>());
   }
 
   /**
@@ -123,7 +124,7 @@ public static <E> ConcurrentHashMultiset<E> create(Iterable<? extends E> element
    */
   @Beta
   public static <E> ConcurrentHashMultiset<E> create(ConcurrentMap<E, AtomicInteger> countMap) {
-    return new ConcurrentHashMultiset<E>(countMap);
+    return new ConcurrentHashMultiset<>(countMap);
   }
 
   @VisibleForTesting
@@ -141,7 +142,7 @@ public static <E> ConcurrentHashMultiset<E> create(ConcurrentMap<E, AtomicIntege
    * @return the nonnegative number of occurrences of the element
    */
   @Override
-  public int count(@Nullable Object element) {
+  public int count(@CheckForNull Object element) {
     AtomicInteger existingCounter = Maps.safeGet(countMap, element);
     return (existingCounter == null) ? 0 : existingCounter.get();
   }
@@ -173,7 +174,8 @@ public Object[] toArray() {
   }
 
   @Override
-  public <T> T[] toArray(T[] array) {
+  @SuppressWarnings("nullness") // b/192354773 in our checker affects toArray declarations
+  public <T extends @Nullable Object> T[] toArray(T[] array) {
     return snapshot().toArray(array);
   }
 
@@ -210,7 +212,7 @@ public int add(E element, int occurrences) {
     if (occurrences == 0) {
       return count(element);
     }
-    CollectPreconditions.checkPositive(occurrences, "occurences");
+    CollectPreconditions.checkPositive(occurrences, "occurrences");
 
     while (true) {
       AtomicInteger existingCounter = Maps.safeGet(countMap, element);
@@ -272,11 +274,11 @@ public int add(E element, int occurrences) {
    */
   @CanIgnoreReturnValue
   @Override
-  public int remove(@Nullable Object element, int occurrences) {
+  public int remove(@CheckForNull Object element, int occurrences) {
     if (occurrences == 0) {
       return count(element);
     }
-    CollectPreconditions.checkPositive(occurrences, "occurences");
+    CollectPreconditions.checkPositive(occurrences, "occurrences");
 
     AtomicInteger existingCounter = Maps.safeGet(countMap, element);
     if (existingCounter == null) {
@@ -313,11 +315,11 @@ public int remove(@Nullable Object element, int occurrences) {
    * @throws IllegalArgumentException if {@code occurrences} is negative
    */
   @CanIgnoreReturnValue
-  public boolean removeExactly(@Nullable Object element, int occurrences) {
+  public boolean removeExactly(@CheckForNull Object element, int occurrences) {
     if (occurrences == 0) {
       return true;
     }
-    CollectPreconditions.checkPositive(occurrences, "occurences");
+    CollectPreconditions.checkPositive(occurrences, "occurrences");
 
     AtomicInteger existingCounter = Maps.safeGet(countMap, element);
     if (existingCounter == null) {
@@ -451,7 +453,7 @@ public boolean setCount(E element, int expectedOldCount, int newCount) {
 
   @Override
   Set<E> createElementSet() {
-    final Set<E> delegate = countMap.keySet();
+    Set<E> delegate = countMap.keySet();
     return new ForwardingSet<E>() {
       @Override
       protected Set<E> delegate() {
@@ -459,7 +461,7 @@ protected Set<E> delegate() {
       }
 
       @Override
-      public boolean contains(@Nullable Object object) {
+      public boolean contains(@CheckForNull Object object) {
         return object != null && Collections2.safeContains(delegate, object);
       }
 
@@ -469,7 +471,7 @@ public boolean containsAll(Collection<?> collection) {
       }
 
       @Override
-      public boolean remove(@Nullable Object object) {
+      public boolean remove(@CheckForNull Object object) {
         return object != null && Collections2.safeRemove(delegate, object);
       }
 
@@ -508,12 +510,13 @@ public boolean isEmpty() {
   Iterator<Entry<E>> entryIterator() {
     // AbstractIterator makes this fairly clean, but it doesn't support remove(). To support
     // remove(), we create an AbstractIterator, and then use ForwardingIterator to delegate to it.
-    final Iterator<Entry<E>> readOnlyIterator =
+    Iterator<Entry<E>> readOnlyIterator =
         new AbstractIterator<Entry<E>>() {
           private final Iterator<Map.Entry<E, AtomicInteger>> mapEntries =
               countMap.entrySet().iterator();
 
           @Override
+          @CheckForNull
           protected Entry<E> computeNext() {
             while (true) {
               if (!mapEntries.hasNext()) {
@@ -529,7 +532,7 @@ protected Entry<E> computeNext() {
         };
 
     return new ForwardingIterator<Entry<E>>() {
-      private @Nullable Entry<E> last;
+      @CheckForNull private Entry<E> last;
 
       @Override
       protected Iterator<Entry<E>> delegate() {
@@ -544,7 +547,7 @@ public Entry<E> next() {
 
       @Override
       public void remove() {
-        checkRemove(last != null);
+        checkState(last != null, "no calls to next() since the last call to remove()");
         ConcurrentHashMultiset.this.setCount(last.getElement(), 0);
         last = null;
       }
@@ -579,7 +582,8 @@ public Object[] toArray() {
     }
 
     @Override
-    public <T> T[] toArray(T[] array) {
+    @SuppressWarnings("nullness") // b/192354773 in our checker affects toArray declarations
+    public <T extends @Nullable Object> T[] toArray(T[] array) {
       return snapshot().toArray(array);
     }
 
diff --git a/guava/src/com/google/common/collect/ConsumingQueueIterator.java b/guava/src/com/google/common/collect/ConsumingQueueIterator.java
index 2f288f041f4e..7721e1277ca8 100644
--- a/guava/src/com/google/common/collect/ConsumingQueueIterator.java
+++ b/guava/src/com/google/common/collect/ConsumingQueueIterator.java
@@ -17,29 +17,30 @@
 import static com.google.common.base.Preconditions.checkNotNull;
 
 import com.google.common.annotations.GwtCompatible;
-import java.util.ArrayDeque;
-import java.util.Collections;
 import java.util.Queue;
+import javax.annotation.CheckForNull;
+import org.checkerframework.checker.nullness.qual.Nullable;
 
 /**
  * An Iterator implementation which draws elements from a queue, removing them from the queue as it
  * iterates.
  */
 @GwtCompatible
-class ConsumingQueueIterator<T> extends AbstractIterator<T> {
+@ElementTypesAreNonnullByDefault
+final class ConsumingQueueIterator<T extends @Nullable Object> extends AbstractIterator<T> {
   private final Queue<T> queue;
 
-  ConsumingQueueIterator(T... elements) {
-    this.queue = new ArrayDeque<T>(elements.length);
-    Collections.addAll(queue, elements);
-  }
-
   ConsumingQueueIterator(Queue<T> queue) {
     this.queue = checkNotNull(queue);
   }
 
   @Override
+  @CheckForNull
   public T computeNext() {
-    return queue.isEmpty() ? endOfData() : queue.remove();
+    // TODO(b/192579700): Use a ternary once it no longer confuses our nullness checker.
+    if (queue.isEmpty()) {
+      return endOfData();
+    }
+    return queue.remove();
   }
 }
diff --git a/guava/src/com/google/common/collect/ContiguousSet.java b/guava/src/com/google/common/collect/ContiguousSet.java
index 9002b8e47684..b3e4889d7cf7 100644
--- a/guava/src/com/google/common/collect/ContiguousSet.java
+++ b/guava/src/com/google/common/collect/ContiguousSet.java
@@ -16,6 +16,7 @@
 
 import static com.google.common.base.Preconditions.checkArgument;
 import static com.google.common.base.Preconditions.checkNotNull;
+import static java.util.Objects.requireNonNull;
 
 import com.google.common.annotations.Beta;
 import com.google.common.annotations.GwtCompatible;
@@ -49,6 +50,7 @@
  */
 @GwtCompatible(emulated = true)
 @SuppressWarnings("rawtypes") // allow ungenerified Comparable types
+@ElementTypesAreNonnullByDefault
 public abstract class ContiguousSet<C extends Comparable> extends ImmutableSortedSet<C> {
   /**
    * Returns a {@code ContiguousSet} containing the same values in the given domain {@linkplain
@@ -74,13 +76,19 @@ public static <C extends Comparable> ContiguousSet<C> create(
       throw new IllegalArgumentException(e);
     }
 
-    // Per class spec, we are allowed to throw CCE if necessary
-    boolean empty =
-        effectiveRange.isEmpty()
-            || Range.compareOrThrow(
-                    range.lowerBound.leastValueAbove(domain),
-                    range.upperBound.greatestValueBelow(domain))
-                > 0;
+    boolean empty;
+    if (effectiveRange.isEmpty()) {
+      empty = true;
+    } else {
+      /*
+       * requireNonNull is safe because the effectiveRange operations above would have thrown or
+       * effectiveRange.isEmpty() would have returned true.
+       */
+      C afterLower = requireNonNull(range.lowerBound.leastValueAbove(domain));
+      C beforeUpper = requireNonNull(range.upperBound.greatestValueBelow(domain));
+      // Per class spec, we are allowed to throw CCE if necessary
+      empty = Range.compareOrThrow(afterLower, beforeUpper) > 0;
+    }
 
     return empty
         ? new EmptyContiguousSet<C>(domain)
@@ -234,7 +242,7 @@ abstract ContiguousSet<C> subSetImpl(
   @Override
   @GwtIncompatible // NavigableSet
   ImmutableSortedSet<C> createDescendingSet() {
-    return new DescendingImmutableSortedSet<C>(this);
+    return new DescendingImmutableSortedSet<>(this);
   }
 
   /** Returns a short-hand representation of the contents such as {@code "[1..100]"}. */
diff --git a/guava/src/com/google/common/collect/Count.java b/guava/src/com/google/common/collect/Count.java
index e2da82a36144..7aa555080135 100644
--- a/guava/src/com/google/common/collect/Count.java
+++ b/guava/src/com/google/common/collect/Count.java
@@ -16,7 +16,7 @@
 
 import com.google.common.annotations.GwtCompatible;
 import java.io.Serializable;
-import org.checkerframework.checker.nullness.qual.Nullable;
+import javax.annotation.CheckForNull;
 
 /**
  * A mutable value of type {@code int}, for multisets to use in tracking counts of values.
@@ -24,6 +24,7 @@
  * @author Louis Wasserman
  */
 @GwtCompatible
+@ElementTypesAreNonnullByDefault
 final class Count implements Serializable {
   private int value;
 
@@ -59,7 +60,7 @@ public int hashCode() {
   }
 
   @Override
-  public boolean equals(@Nullable Object obj) {
+  public boolean equals(@CheckForNull Object obj) {
     return obj instanceof Count && ((Count) obj).value == value;
   }
 
diff --git a/guava/src/com/google/common/collect/Cut.java b/guava/src/com/google/common/collect/Cut.java
index 8f6cd818f738..21fe5ff2dd9f 100644
--- a/guava/src/com/google/common/collect/Cut.java
+++ b/guava/src/com/google/common/collect/Cut.java
@@ -20,7 +20,7 @@
 import com.google.common.primitives.Booleans;
 import java.io.Serializable;
 import java.util.NoSuchElementException;
-import org.checkerframework.checker.nullness.qual.Nullable;
+import javax.annotation.CheckForNull;
 
 /**
  * Implementation detail for the internal structure of {@link Range} instances. Represents a unique
@@ -32,10 +32,11 @@
  * @author Kevin Bourrillion
  */
 @GwtCompatible
+@ElementTypesAreNonnullByDefault
 abstract class Cut<C extends Comparable> implements Comparable<Cut<C>>, Serializable {
-  final @Nullable C endpoint;
+  final C endpoint;
 
-  Cut(@Nullable C endpoint) {
+  Cut(C endpoint) {
     this.endpoint = endpoint;
   }
 
@@ -53,8 +54,10 @@ abstract class Cut<C extends Comparable> implements Comparable<Cut<C>>, Serializ
 
   abstract void describeAsUpperBound(StringBuilder sb);
 
+  @CheckForNull
   abstract C leastValueAbove(DiscreteDomain<C> domain);
 
+  @CheckForNull
   abstract C greatestValueBelow(DiscreteDomain<C> domain);
 
   /*
@@ -88,14 +91,15 @@ C endpoint() {
 
   @SuppressWarnings("unchecked") // catching CCE
   @Override
-  public boolean equals(Object obj) {
+  public boolean equals(@CheckForNull Object obj) {
     if (obj instanceof Cut) {
       // It might not really be a Cut<C>, but we'll catch a CCE if it's not
       Cut<C> that = (Cut<C>) obj;
       try {
         int compareResult = compareTo(that);
         return compareResult == 0;
-      } catch (ClassCastException ignored) {
+      } catch (ClassCastException wastNotComparableToOurType) {
+        return false;
       }
     }
     return false;
@@ -120,7 +124,13 @@ private static final class BelowAll extends Cut<Comparable<?>> {
     private static final BelowAll INSTANCE = new BelowAll();
 
     private BelowAll() {
-      super(null);
+      /*
+       * No code ever sees this bogus value for `endpoint`: This class overrides both methods that
+       * use the `endpoint` field, compareTo() and endpoint(). Additionally, the main implementation
+       * of Cut.compareTo checks for belowAll before reading accessing `endpoint` on another Cut
+       * instance.
+       */
+      super("");
     }
 
     @Override
@@ -219,7 +229,8 @@ private static final class AboveAll extends Cut<Comparable<?>> {
     private static final AboveAll INSTANCE = new AboveAll();
 
     private AboveAll() {
-      super(null);
+      // For discussion of "", see BelowAll.
+      super("");
     }
 
     @Override
@@ -297,7 +308,7 @@ private Object readResolve() {
   }
 
   static <C extends Comparable> Cut<C> belowValue(C endpoint) {
-    return new BelowValue<C>(endpoint);
+    return new BelowValue<>(endpoint);
   }
 
   private static final class BelowValue<C extends Comparable> extends Cut<C> {
@@ -326,7 +337,7 @@ Cut<C> withLowerBoundType(BoundType boundType, DiscreteDomain<C> domain) {
         case CLOSED:
           return this;
         case OPEN:
-          @Nullable C previous = domain.previous(endpoint);
+          C previous = domain.previous(endpoint);
           return (previous == null) ? Cut.<C>belowAll() : new AboveValue<C>(previous);
         default:
           throw new AssertionError();
@@ -337,7 +348,7 @@ Cut<C> withLowerBoundType(BoundType boundType, DiscreteDomain<C> domain) {
     Cut<C> withUpperBoundType(BoundType boundType, DiscreteDomain<C> domain) {
       switch (boundType) {
         case CLOSED:
-          @Nullable C previous = domain.previous(endpoint);
+          C previous = domain.previous(endpoint);
           return (previous == null) ? Cut.<C>aboveAll() : new AboveValue<C>(previous);
         case OPEN:
           return this;
@@ -362,6 +373,7 @@ C leastValueAbove(DiscreteDomain<C> domain) {
     }
 
     @Override
+    @CheckForNull
     C greatestValueBelow(DiscreteDomain<C> domain) {
       return domain.previous(endpoint);
     }
@@ -380,7 +392,7 @@ public String toString() {
   }
 
   static <C extends Comparable> Cut<C> aboveValue(C endpoint) {
-    return new AboveValue<C>(endpoint);
+    return new AboveValue<>(endpoint);
   }
 
   private static final class AboveValue<C extends Comparable> extends Cut<C> {
@@ -409,7 +421,7 @@ Cut<C> withLowerBoundType(BoundType boundType, DiscreteDomain<C> domain) {
         case OPEN:
           return this;
         case CLOSED:
-          @Nullable C next = domain.next(endpoint);
+          C next = domain.next(endpoint);
           return (next == null) ? Cut.<C>belowAll() : belowValue(next);
         default:
           throw new AssertionError();
@@ -420,7 +432,7 @@ Cut<C> withLowerBoundType(BoundType boundType, DiscreteDomain<C> domain) {
     Cut<C> withUpperBoundType(BoundType boundType, DiscreteDomain<C> domain) {
       switch (boundType) {
         case OPEN:
-          @Nullable C next = domain.next(endpoint);
+          C next = domain.next(endpoint);
           return (next == null) ? Cut.<C>aboveAll() : belowValue(next);
         case CLOSED:
           return this;
@@ -440,6 +452,7 @@ void describeAsUpperBound(StringBuilder sb) {
     }
 
     @Override
+    @CheckForNull
     C leastValueAbove(DiscreteDomain<C> domain) {
       return domain.next(endpoint);
     }
diff --git a/guava/src/com/google/common/collect/DenseImmutableTable.java b/guava/src/com/google/common/collect/DenseImmutableTable.java
index 91c2d484f041..9de77c57f213 100644
--- a/guava/src/com/google/common/collect/DenseImmutableTable.java
+++ b/guava/src/com/google/common/collect/DenseImmutableTable.java
@@ -14,16 +14,20 @@
 
 package com.google.common.collect;
 
+import static java.util.Objects.requireNonNull;
+
 import com.google.common.annotations.GwtCompatible;
 import com.google.common.collect.ImmutableMap.IteratorBasedImmutableMap;
 import com.google.errorprone.annotations.Immutable;
 import com.google.j2objc.annotations.WeakOuter;
 import java.util.Map;
+import javax.annotation.CheckForNull;
 import org.checkerframework.checker.nullness.qual.Nullable;
 
 /** A {@code RegularImmutableTable} optimized for dense data. */
 @GwtCompatible
 @Immutable(containerOf = {"R", "C", "V"})
+@ElementTypesAreNonnullByDefault
 final class DenseImmutableTable<R, C, V> extends RegularImmutableTable<R, C, V> {
   private final ImmutableMap<R, Integer> rowKeyToIndex;
   private final ImmutableMap<C, Integer> columnKeyToIndex;
@@ -37,7 +41,7 @@ final class DenseImmutableTable<R, C, V> extends RegularImmutableTable<R, C, V>
   private final int[] columnCounts;
 
   @SuppressWarnings("Immutable") // We don't modify this after construction.
-  private final V[][] values;
+  private final @Nullable V[][] values;
 
   // For each cell in iteration order, the index of that cell's row key in the row key list.
   @SuppressWarnings("Immutable") // We don't modify this after construction.
@@ -52,7 +56,8 @@ final class DenseImmutableTable<R, C, V> extends RegularImmutableTable<R, C, V>
       ImmutableSet<R> rowSpace,
       ImmutableSet<C> columnSpace) {
     @SuppressWarnings("unchecked")
-    V[][] array = (V[][]) new Object[rowSpace.size()][columnSpace.size()];
+    @Nullable
+    V[][] array = (@Nullable V[][]) new Object[rowSpace.size()][columnSpace.size()];
     this.values = array;
     this.rowKeyToIndex = Maps.indexMap(rowSpace);
     this.columnKeyToIndex = Maps.indexMap(columnSpace);
@@ -64,8 +69,9 @@ final class DenseImmutableTable<R, C, V> extends RegularImmutableTable<R, C, V>
       Cell<R, C, V> cell = cellList.get(i);
       R rowKey = cell.getRowKey();
       C columnKey = cell.getColumnKey();
-      int rowIndex = rowKeyToIndex.get(rowKey);
-      int columnIndex = columnKeyToIndex.get(columnKey);
+      // The requireNonNull calls are safe because we construct the indexes with indexMap.
+      int rowIndex = requireNonNull(rowKeyToIndex.get(rowKey));
+      int columnIndex = requireNonNull(columnKeyToIndex.get(columnKey));
       V existingValue = values[rowIndex][columnIndex];
       checkNoDuplicate(rowKey, columnKey, existingValue, cell.getValue());
       values[rowIndex][columnIndex] = cell.getValue();
@@ -99,7 +105,8 @@ K getKey(int index) {
       return keyToIndex().keySet().asList().get(index);
     }
 
-    abstract @Nullable V getValue(int keyIndex);
+    @CheckForNull
+    abstract V getValue(int keyIndex);
 
     @Override
     ImmutableSet<K> createKeySet() {
@@ -112,7 +119,8 @@ public int size() {
     }
 
     @Override
-    public V get(@Nullable Object key) {
+    @CheckForNull
+    public V get(@CheckForNull Object key) {
       Integer keyIndex = keyToIndex().get(key);
       return (keyIndex == null) ? null : getValue(keyIndex);
     }
@@ -124,6 +132,7 @@ UnmodifiableIterator<Entry<K, V>> entryIterator() {
         private final int maxIndex = keyToIndex().size();
 
         @Override
+        @CheckForNull
         protected Entry<K, V> computeNext() {
           for (index++; index < maxIndex; index++) {
             V value = getValue(index);
@@ -151,6 +160,7 @@ ImmutableMap<C, Integer> keyToIndex() {
     }
 
     @Override
+    @CheckForNull
     V getValue(int keyIndex) {
       return values[rowIndex][keyIndex];
     }
@@ -175,6 +185,7 @@ ImmutableMap<R, Integer> keyToIndex() {
     }
 
     @Override
+    @CheckForNull
     V getValue(int keyIndex) {
       return values[keyIndex][columnIndex];
     }
@@ -244,7 +255,8 @@ public ImmutableMap<R, Map<C, V>> rowMap() {
   }
 
   @Override
-  public V get(@Nullable Object rowKey, @Nullable Object columnKey) {
+  @CheckForNull
+  public V get(@CheckForNull Object rowKey, @CheckForNull Object columnKey) {
     Integer rowIndex = rowKeyToIndex.get(rowKey);
     Integer columnIndex = columnKeyToIndex.get(columnKey);
     return ((rowIndex == null) || (columnIndex == null)) ? null : values[rowIndex][columnIndex];
@@ -261,13 +273,15 @@ Cell<R, C, V> getCell(int index) {
     int columnIndex = cellColumnIndices[index];
     R rowKey = rowKeySet().asList().get(rowIndex);
     C columnKey = columnKeySet().asList().get(columnIndex);
-    V value = values[rowIndex][columnIndex];
+    // requireNonNull is safe because we use indexes that were populated by the constructor.
+    V value = requireNonNull(values[rowIndex][columnIndex]);
     return cellOf(rowKey, columnKey, value);
   }
 
   @Override
   V getValue(int index) {
-    return values[cellRowIndices[index]][cellColumnIndices[index]];
+    // requireNonNull is safe because we use indexes that were populated by the constructor.
+    return requireNonNull(values[cellRowIndices[index]][cellColumnIndices[index]]);
   }
 
   @Override
diff --git a/guava/src/com/google/common/collect/DescendingImmutableSortedMultiset.java b/guava/src/com/google/common/collect/DescendingImmutableSortedMultiset.java
index 346bafb5ee20..181731cc4896 100644
--- a/guava/src/com/google/common/collect/DescendingImmutableSortedMultiset.java
+++ b/guava/src/com/google/common/collect/DescendingImmutableSortedMultiset.java
@@ -15,7 +15,7 @@
 package com.google.common.collect;
 
 import com.google.common.annotations.GwtIncompatible;
-import org.checkerframework.checker.nullness.qual.Nullable;
+import javax.annotation.CheckForNull;
 
 /**
  * A descending wrapper around an {@code ImmutableSortedMultiset}
@@ -24,6 +24,7 @@
  */
 @SuppressWarnings("serial") // uses writeReplace, not default serialization
 @GwtIncompatible
+@ElementTypesAreNonnullByDefault
 final class DescendingImmutableSortedMultiset<E> extends ImmutableSortedMultiset<E> {
   private final transient ImmutableSortedMultiset<E> forward;
 
@@ -32,16 +33,18 @@ final class DescendingImmutableSortedMultiset<E> extends ImmutableSortedMultiset
   }
 
   @Override
-  public int count(@Nullable Object element) {
+  public int count(@CheckForNull Object element) {
     return forward.count(element);
   }
 
   @Override
+  @CheckForNull
   public Entry<E> firstEntry() {
     return forward.lastEntry();
   }
 
   @Override
+  @CheckForNull
   public Entry<E> lastEntry() {
     return forward.firstEntry();
   }
diff --git a/guava/src/com/google/common/collect/DescendingImmutableSortedSet.java b/guava/src/com/google/common/collect/DescendingImmutableSortedSet.java
index 635437837386..88c7d6b5cca0 100644
--- a/guava/src/com/google/common/collect/DescendingImmutableSortedSet.java
+++ b/guava/src/com/google/common/collect/DescendingImmutableSortedSet.java
@@ -17,7 +17,7 @@
 package com.google.common.collect;
 
 import com.google.common.annotations.GwtIncompatible;
-import org.checkerframework.checker.nullness.qual.Nullable;
+import javax.annotation.CheckForNull;
 
 /**
  * Skeletal implementation of {@link ImmutableSortedSet#descendingSet()}.
@@ -25,6 +25,7 @@
  * @author Louis Wasserman
  */
 @GwtIncompatible
+@ElementTypesAreNonnullByDefault
 final class DescendingImmutableSortedSet<E> extends ImmutableSortedSet<E> {
   private final ImmutableSortedSet<E> forward;
 
@@ -34,7 +35,7 @@ final class DescendingImmutableSortedSet<E> extends ImmutableSortedSet<E> {
   }
 
   @Override
-  public boolean contains(@Nullable Object object) {
+  public boolean contains(@CheckForNull Object object) {
     return forward.contains(object);
   }
 
@@ -83,27 +84,31 @@ ImmutableSortedSet<E> createDescendingSet() {
   }
 
   @Override
+  @CheckForNull
   public E lower(E element) {
     return forward.higher(element);
   }
 
   @Override
+  @CheckForNull
   public E floor(E element) {
     return forward.ceiling(element);
   }
 
   @Override
+  @CheckForNull
   public E ceiling(E element) {
     return forward.floor(element);
   }
 
   @Override
+  @CheckForNull
   public E higher(E element) {
     return forward.lower(element);
   }
 
   @Override
-  int indexOf(@Nullable Object target) {
+  int indexOf(@CheckForNull Object target) {
     int index = forward.indexOf(target);
     if (index == -1) {
       return index;
diff --git a/guava/src/com/google/common/collect/DescendingMultiset.java b/guava/src/com/google/common/collect/DescendingMultiset.java
index 74590ac1544a..7db0fbbd4916 100644
--- a/guava/src/com/google/common/collect/DescendingMultiset.java
+++ b/guava/src/com/google/common/collect/DescendingMultiset.java
@@ -22,6 +22,7 @@
 import java.util.Iterator;
 import java.util.NavigableSet;
 import java.util.Set;
+import javax.annotation.CheckForNull;
 import org.checkerframework.checker.nullness.qual.Nullable;
 
 /**
@@ -31,10 +32,12 @@
  * @author Louis Wasserman
  */
 @GwtCompatible(emulated = true)
-abstract class DescendingMultiset<E> extends ForwardingMultiset<E> implements SortedMultiset<E> {
+@ElementTypesAreNonnullByDefault
+abstract class DescendingMultiset<E extends @Nullable Object> extends ForwardingMultiset<E>
+    implements SortedMultiset<E> {
   abstract SortedMultiset<E> forwardMultiset();
 
-  private transient @Nullable Comparator<? super E> comparator;
+  @CheckForNull private transient Comparator<? super E> comparator;
 
   @Override
   public Comparator<? super E> comparator() {
@@ -45,42 +48,47 @@ public Comparator<? super E> comparator() {
     return result;
   }
 
-  private transient @Nullable NavigableSet<E> elementSet;
+  @CheckForNull private transient NavigableSet<E> elementSet;
 
   @Override
   public NavigableSet<E> elementSet() {
     NavigableSet<E> result = elementSet;
     if (result == null) {
-      return elementSet = new SortedMultisets.NavigableElementSet<E>(this);
+      return elementSet = new SortedMultisets.NavigableElementSet<>(this);
     }
     return result;
   }
 
   @Override
+  @CheckForNull
   public Entry<E> pollFirstEntry() {
     return forwardMultiset().pollLastEntry();
   }
 
   @Override
+  @CheckForNull
   public Entry<E> pollLastEntry() {
     return forwardMultiset().pollFirstEntry();
   }
 
   @Override
-  public SortedMultiset<E> headMultiset(E toElement, BoundType boundType) {
+  public SortedMultiset<E> headMultiset(@ParametricNullness E toElement, BoundType boundType) {
     return forwardMultiset().tailMultiset(toElement, boundType).descendingMultiset();
   }
 
   @Override
   public SortedMultiset<E> subMultiset(
-      E fromElement, BoundType fromBoundType, E toElement, BoundType toBoundType) {
+      @ParametricNullness E fromElement,
+      BoundType fromBoundType,
+      @ParametricNullness E toElement,
+      BoundType toBoundType) {
     return forwardMultiset()
         .subMultiset(toElement, toBoundType, fromElement, fromBoundType)
         .descendingMultiset();
   }
 
   @Override
-  public SortedMultiset<E> tailMultiset(E fromElement, BoundType boundType) {
+  public SortedMultiset<E> tailMultiset(@ParametricNullness E fromElement, BoundType boundType) {
     return forwardMultiset().headMultiset(fromElement, boundType).descendingMultiset();
   }
 
@@ -95,18 +103,20 @@ public SortedMultiset<E> descendingMultiset() {
   }
 
   @Override
+  @CheckForNull
   public Entry<E> firstEntry() {
     return forwardMultiset().lastEntry();
   }
 
   @Override
+  @CheckForNull
   public Entry<E> lastEntry() {
     return forwardMultiset().firstEntry();
   }
 
   abstract Iterator<Entry<E>> entryIterator();
 
-  private transient @Nullable Set<Entry<E>> entrySet;
+  @CheckForNull private transient Set<Entry<E>> entrySet;
 
   @Override
   public Set<Entry<E>> entrySet() {
@@ -141,12 +151,13 @@ public Iterator<E> iterator() {
   }
 
   @Override
-  public Object[] toArray() {
+  public @Nullable Object[] toArray() {
     return standardToArray();
   }
 
   @Override
-  public <T> T[] toArray(T[] array) {
+  @SuppressWarnings("nullness") // b/192354773 in our checker affects toArray declarations
+  public <T extends @Nullable Object> T[] toArray(T[] array) {
     return standardToArray(array);
   }
 
diff --git a/guava/src/com/google/common/collect/DiscreteDomain.java b/guava/src/com/google/common/collect/DiscreteDomain.java
index 3777a6d4bbc9..0233feb76e10 100644
--- a/guava/src/com/google/common/collect/DiscreteDomain.java
+++ b/guava/src/com/google/common/collect/DiscreteDomain.java
@@ -25,6 +25,7 @@
 import java.io.Serializable;
 import java.math.BigInteger;
 import java.util.NoSuchElementException;
+import javax.annotation.CheckForNull;
 
 /**
  * A descriptor for a <i>discrete</i> {@code Comparable} domain such as all {@link Integer}
@@ -36,13 +37,14 @@
  * represent partial domains such as "prime integers" or "strings of length 5."
  *
  * <p>See the Guava User Guide section on <a href=
- * "https://github.com/google/guava/wiki/RangesExplained#discrete-domains"> {@code
+ * "https://github.com/google/guava/wiki/RangesExplained#discrete-domains">{@code
  * DiscreteDomain}</a>.
  *
  * @author Kevin Bourrillion
  * @since 10.0
  */
 @GwtCompatible
+@ElementTypesAreNonnullByDefault
 public abstract class DiscreteDomain<C extends Comparable> {
 
   /**
@@ -62,18 +64,21 @@ private static final class IntegerDomain extends DiscreteDomain<Integer> impleme
     }
 
     @Override
+    @CheckForNull
     public Integer next(Integer value) {
       int i = value;
       return (i == Integer.MAX_VALUE) ? null : i + 1;
     }
 
     @Override
+    @CheckForNull
     public Integer previous(Integer value) {
       int i = value;
       return (i == Integer.MIN_VALUE) ? null : i - 1;
     }
 
     @Override
+    @SuppressWarnings("value:argument") // origin + distance must fit in an int
     Integer offset(Integer origin, long distance) {
       checkNonnegative(distance, "distance");
       return Ints.checkedCast(origin.longValue() + distance);
@@ -123,12 +128,14 @@ private static final class LongDomain extends DiscreteDomain<Long> implements Se
     }
 
     @Override
+    @CheckForNull
     public Long next(Long value) {
       long l = value;
       return (l == Long.MAX_VALUE) ? null : l + 1;
     }
 
     @Override
+    @CheckForNull
     public Long previous(Long value) {
       long l = value;
       return (l == Long.MIN_VALUE) ? null : l - 1;
@@ -248,11 +255,16 @@ private DiscreteDomain(boolean supportsFastOffset) {
    * #next} on {@code origin} {@code distance} times.
    */
   C offset(C origin, long distance) {
+    C current = origin;
     checkNonnegative(distance, "distance");
     for (long i = 0; i < distance; i++) {
-      origin = next(origin);
+      current = next(current);
+      if (current == null) {
+        throw new IllegalArgumentException(
+            "overflowed computing offset(" + origin + ", " + distance + ")");
+      }
     }
-    return origin;
+    return current;
   }
 
   /**
@@ -263,6 +275,7 @@ C offset(C origin, long distance) {
    * @return the least value greater than {@code value}, or {@code null} if {@code value} is {@code
    *     maxValue()}
    */
+  @CheckForNull
   public abstract C next(C value);
 
   /**
@@ -273,6 +286,7 @@ C offset(C origin, long distance) {
    * @return the greatest value less than {@code value}, or {@code null} if {@code value} is {@code
    *     minValue()}
    */
+  @CheckForNull
   public abstract C previous(C value);
 
   /**
diff --git a/guava/src/com/google/common/collect/ElementTypesAreNonnullByDefault.java b/guava/src/com/google/common/collect/ElementTypesAreNonnullByDefault.java
new file mode 100644
index 000000000000..e1c640ff5db4
--- /dev/null
+++ b/guava/src/com/google/common/collect/ElementTypesAreNonnullByDefault.java
@@ -0,0 +1,41 @@
+/*
+ * Copyright (C) 2021 The Guava Authors
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package com.google.common.collect;
+
+import static java.lang.annotation.ElementType.FIELD;
+import static java.lang.annotation.ElementType.METHOD;
+import static java.lang.annotation.ElementType.PARAMETER;
+import static java.lang.annotation.ElementType.TYPE;
+import static java.lang.annotation.RetentionPolicy.RUNTIME;
+
+import com.google.common.annotations.GwtCompatible;
+import java.lang.annotation.Retention;
+import java.lang.annotation.Target;
+import javax.annotation.Nonnull;
+import javax.annotation.meta.TypeQualifierDefault;
+
+/**
+ * Marks all "top-level" types as non-null in a way that is recognized by Kotlin. Note that this
+ * unfortunately includes type-variable usages, so we also provide {@link ParametricNullness} to
+ * "undo" it as best we can.
+ */
+@GwtCompatible
+@Retention(RUNTIME)
+@Target(TYPE)
+@TypeQualifierDefault({FIELD, METHOD, PARAMETER})
+@Nonnull
+@interface ElementTypesAreNonnullByDefault {}
diff --git a/guava/src/com/google/common/collect/EmptyContiguousSet.java b/guava/src/com/google/common/collect/EmptyContiguousSet.java
index fd90124b59c3..50d7b126a27a 100644
--- a/guava/src/com/google/common/collect/EmptyContiguousSet.java
+++ b/guava/src/com/google/common/collect/EmptyContiguousSet.java
@@ -18,7 +18,7 @@
 import java.io.Serializable;
 import java.util.NoSuchElementException;
 import java.util.Set;
-import org.checkerframework.checker.nullness.qual.Nullable;
+import javax.annotation.CheckForNull;
 
 /**
  * An empty contiguous set.
@@ -27,6 +27,7 @@
  */
 @GwtCompatible(emulated = true)
 @SuppressWarnings("rawtypes") // allow ungenerified Comparable types
+@ElementTypesAreNonnullByDefault
 final class EmptyContiguousSet<C extends Comparable> extends ContiguousSet<C> {
   EmptyContiguousSet(DiscreteDomain<C> domain) {
     super(domain);
@@ -79,13 +80,13 @@ ContiguousSet<C> tailSetImpl(C fromElement, boolean fromInclusive) {
   }
 
   @Override
-  public boolean contains(Object object) {
+  public boolean contains(@CheckForNull Object object) {
     return false;
   }
 
   @GwtIncompatible // not used by GWT emulation
   @Override
-  int indexOf(Object target) {
+  int indexOf(@CheckForNull Object target) {
     return -1;
   }
 
@@ -121,7 +122,7 @@ public String toString() {
   }
 
   @Override
-  public boolean equals(@Nullable Object object) {
+  public boolean equals(@CheckForNull Object object) {
     if (object instanceof Set) {
       Set<?> that = (Set<?>) object;
       return that.isEmpty();
@@ -149,7 +150,7 @@ private SerializedForm(DiscreteDomain<C> domain) {
     }
 
     private Object readResolve() {
-      return new EmptyContiguousSet<C>(domain);
+      return new EmptyContiguousSet<>(domain);
     }
 
     private static final long serialVersionUID = 0;
@@ -158,7 +159,7 @@ private Object readResolve() {
   @GwtIncompatible // serialization
   @Override
   Object writeReplace() {
-    return new SerializedForm<C>(domain);
+    return new SerializedForm<>(domain);
   }
 
   @GwtIncompatible // NavigableSet
diff --git a/guava/src/com/google/common/collect/EmptyImmutableListMultimap.java b/guava/src/com/google/common/collect/EmptyImmutableListMultimap.java
index bdd51d5e2644..5213d3411472 100644
--- a/guava/src/com/google/common/collect/EmptyImmutableListMultimap.java
+++ b/guava/src/com/google/common/collect/EmptyImmutableListMultimap.java
@@ -26,6 +26,7 @@
  */
 @AnnotatedFor({"nullness"})
 @GwtCompatible(serializable = true)
+@ElementTypesAreNonnullByDefault
 class EmptyImmutableListMultimap extends ImmutableListMultimap<Object, Object> {
   static final EmptyImmutableListMultimap INSTANCE = new EmptyImmutableListMultimap();
 
diff --git a/guava/src/com/google/common/collect/EmptyImmutableSetMultimap.java b/guava/src/com/google/common/collect/EmptyImmutableSetMultimap.java
index de8961c130c6..5e6e3c24f51e 100644
--- a/guava/src/com/google/common/collect/EmptyImmutableSetMultimap.java
+++ b/guava/src/com/google/common/collect/EmptyImmutableSetMultimap.java
@@ -26,6 +26,7 @@
  */
 @AnnotatedFor({"nullness"})
 @GwtCompatible(serializable = true)
+@ElementTypesAreNonnullByDefault
 class EmptyImmutableSetMultimap extends ImmutableSetMultimap<Object, Object> {
   static final EmptyImmutableSetMultimap INSTANCE = new EmptyImmutableSetMultimap();
 
diff --git a/guava/src/com/google/common/collect/EnumBiMap.java b/guava/src/com/google/common/collect/EnumBiMap.java
index 630c69d53e48..858d925fbfac 100644
--- a/guava/src/com/google/common/collect/EnumBiMap.java
+++ b/guava/src/com/google/common/collect/EnumBiMap.java
@@ -35,13 +35,14 @@
  * An {@code EnumBiMap} and its inverse are both serializable.
  *
  * <p>See the Guava User Guide article on <a href=
- * "https://github.com/google/guava/wiki/NewCollectionTypesExplained#bimap"> {@code BiMap}</a>.
+ * "https://github.com/google/guava/wiki/NewCollectionTypesExplained#bimap">{@code BiMap}</a>.
  *
  * @author Mike Bostock
  * @since 2.0
  */
 @AnnotatedFor({"nullness"})
 @GwtCompatible(emulated = true)
+@ElementTypesAreNonnullByDefault
 public final class EnumBiMap<K extends Enum<K>, V extends Enum<V>> extends AbstractBiMap<K, V> {
   private transient Class<K> keyType;
   private transient Class<V> valueType;
diff --git a/guava/src/com/google/common/collect/EnumHashBiMap.java b/guava/src/com/google/common/collect/EnumHashBiMap.java
index d20e9fbc744e..ef791afa2994 100644
--- a/guava/src/com/google/common/collect/EnumHashBiMap.java
+++ b/guava/src/com/google/common/collect/EnumHashBiMap.java
@@ -27,6 +27,7 @@
 import java.util.EnumMap;
 import java.util.HashMap;
 import java.util.Map;
+import javax.annotation.CheckForNull;
 import org.checkerframework.checker.nullness.qual.Nullable;
 import org.checkerframework.dataflow.qual.Pure;
 import org.checkerframework.framework.qual.AnnotatedFor;
@@ -37,14 +38,16 @@
  * EnumHashBiMap} and its inverse are both serializable.
  *
  * <p>See the Guava User Guide article on <a href=
- * "https://github.com/google/guava/wiki/NewCollectionTypesExplained#bimap"> {@code BiMap}</a>.
+ * "https://github.com/google/guava/wiki/NewCollectionTypesExplained#bimap">{@code BiMap}</a>.
  *
  * @author Mike Bostock
  * @since 2.0
  */
 @AnnotatedFor({"nullness"})
 @GwtCompatible(emulated = true)
-public final class EnumHashBiMap<K extends Enum<K>, V> extends AbstractBiMap<K, V> {
+@ElementTypesAreNonnullByDefault
+public final class EnumHashBiMap<K extends Enum<K>, V extends @Nullable Object>
+    extends AbstractBiMap<K, V> {
   private transient Class<K> keyType;
 
   /**
@@ -52,7 +55,8 @@ public final class EnumHashBiMap<K extends Enum<K>, V> extends AbstractBiMap<K,
    *
    * @param keyType the key type
    */
-  public static <K extends Enum<K>, V> EnumHashBiMap<K, V> create(Class<K> keyType) {
+  public static <K extends Enum<K>, V extends @Nullable Object> EnumHashBiMap<K, V> create(
+      Class<K> keyType) {
     return new EnumHashBiMap<>(keyType);
   }
 
@@ -66,7 +70,8 @@ public static <K extends Enum<K>, V> EnumHashBiMap<K, V> create(Class<K> keyType
    * @throws IllegalArgumentException if map is not an {@code EnumBiMap} or an {@code EnumHashBiMap}
    *     instance and contains no mappings
    */
-  public static <K extends Enum<K>, V> EnumHashBiMap<K, V> create(Map<K, ? extends V> map) {
+  public static <K extends Enum<K>, V extends @Nullable Object> EnumHashBiMap<K, V> create(
+      Map<K, ? extends V> map) {
     EnumHashBiMap<K, V> bimap = create(EnumBiMap.inferKeyType(map));
     bimap.putAll(map);
     return bimap;
@@ -88,13 +93,19 @@ K checkKey(K key) {
 
   @CanIgnoreReturnValue
   @Override
-  public V put(K key, @Nullable V value) {
+  @SuppressWarnings("RedundantOverride") // b/192446478: RedundantOverride ignores some annotations.
+  // TODO(b/192446998): Remove this override after tools understand nullness better.
+  @CheckForNull
+  public V put(K key, @ParametricNullness V value) {
     return super.put(key, value);
   }
 
   @CanIgnoreReturnValue
   @Override
-  public V forcePut(K key, @Nullable V value) {
+  @SuppressWarnings("RedundantOverride") // b/192446478: RedundantOverride ignores some annotations.
+  // TODO(b/192446998): Remove this override after tools understand nullness better.
+  @CheckForNull
+  public V forcePut(K key, @ParametricNullness V value) {
     return super.forcePut(key, value);
   }
 
diff --git a/guava/src/com/google/common/collect/EnumMultiset.java b/guava/src/com/google/common/collect/EnumMultiset.java
index 16b858932195..8e5136baa877 100644
--- a/guava/src/com/google/common/collect/EnumMultiset.java
+++ b/guava/src/com/google/common/collect/EnumMultiset.java
@@ -32,6 +32,7 @@
 import java.util.Iterator;
 import java.util.NoSuchElementException;
 import java.util.function.ObjIntConsumer;
+import javax.annotation.CheckForNull;
 import org.checkerframework.checker.nullness.qual.Nullable;
 import org.checkerframework.dataflow.qual.Pure;
 import org.checkerframework.framework.qual.AnnotatedFor;
@@ -41,14 +42,14 @@
  * in O(1).
  *
  * <p>See the Guava User Guide article on <a href=
- * "https://github.com/google/guava/wiki/NewCollectionTypesExplained#multiset"> {@code
- * Multiset}</a>.
+ * "https://github.com/google/guava/wiki/NewCollectionTypesExplained#multiset">{@code Multiset}</a>.
  *
  * @author Jared Levy
  * @since 2.0
  */
 @AnnotatedFor({"nullness"})
 @GwtCompatible(emulated = true)
+@ElementTypesAreNonnullByDefault
 public final class EnumMultiset<E extends Enum<E>> extends AbstractMultiset<E>
     implements Serializable {
   /** Creates an empty {@code EnumMultiset}. */
@@ -98,7 +99,7 @@ private EnumMultiset(Class<E> type) {
     this.counts = new int[enumConstants.length];
   }
 
-  private boolean isActuallyE(@Nullable Object o) {
+  private boolean isActuallyE(@CheckForNull Object o) {
     if (o instanceof Enum) {
       Enum<?> e = (Enum<?>) o;
       int index = e.ordinal();
@@ -111,7 +112,7 @@ private boolean isActuallyE(@Nullable Object o) {
    * Returns {@code element} cast to {@code E}, if it actually is a nonnull E. Otherwise, throws
    * either a NullPointerException or a ClassCastException as appropriate.
    */
-  void checkIsE(@Nullable Object element) {
+  private void checkIsE(Object element) {
     checkNotNull(element);
     if (!isActuallyE(element)) {
       throw new ClassCastException("Expected an " + type + " but got " + element);
@@ -129,8 +130,9 @@ public int size() {
   }
 
   @Override
-  public int count(@Nullable Object element) {
-    if (!isActuallyE(element)) {
+  public int count(@CheckForNull Object element) {
+    // isActuallyE checks for null, but we check explicitly to help nullness checkers.
+    if (element == null || !isActuallyE(element)) {
       return 0;
     }
     Enum<?> e = (Enum<?>) element;
@@ -161,8 +163,9 @@ public int add(E element, int occurrences) {
   // Modification Operations
   @CanIgnoreReturnValue
   @Override
-  public int remove(@Nullable Object element, int occurrences) {
-    if (!isActuallyE(element)) {
+  public int remove(@CheckForNull Object element, int occurrences) {
+    // isActuallyE checks for null, but we check explicitly to help nullness checkers.
+    if (element == null || !isActuallyE(element)) {
       return 0;
     }
     Enum<?> e = (Enum<?>) element;
diff --git a/guava/src/com/google/common/collect/EvictingQueue.java b/guava/src/com/google/common/collect/EvictingQueue.java
index 37a65f3e0deb..5667dfa8c054 100644
--- a/guava/src/com/google/common/collect/EvictingQueue.java
+++ b/guava/src/com/google/common/collect/EvictingQueue.java
@@ -45,6 +45,7 @@
  */
 @Beta
 @GwtCompatible
+@ElementTypesAreNonnullByDefault
 public final class EvictingQueue<E> extends ForwardingQueue<E> implements Serializable {
 
   private final Queue<E> delegate;
@@ -53,7 +54,7 @@ public final class EvictingQueue<E> extends ForwardingQueue<E> implements Serial
 
   private EvictingQueue(int maxSize) {
     checkArgument(maxSize >= 0, "maxSize (%s) must >= 0", maxSize);
-    this.delegate = new ArrayDeque<E>(maxSize);
+    this.delegate = new ArrayDeque<>(maxSize);
     this.maxSize = maxSize;
   }
 
@@ -64,7 +65,7 @@ private EvictingQueue(int maxSize) {
    * queue.
    */
   public static <E> EvictingQueue<E> create(int maxSize) {
-    return new EvictingQueue<E>(maxSize);
+    return new EvictingQueue<>(maxSize);
   }
 
   /**
@@ -126,17 +127,19 @@ public boolean addAll(Collection<? extends E> collection) {
   }
 
   @Override
-  public boolean contains(Object object) {
-    return delegate().contains(checkNotNull(object));
+  public Object[] toArray() {
+    /*
+     * If we could, we'd declare the no-arg `Collection.toArray()` to return "Object[] but elements
+     * have the same nullness as E." Since we can't, we declare it to return nullable elements, and
+     * we can override it in our non-null-guaranteeing subtypes to present a better signature to
+     * their users.
+     *
+     * However, the checker *we* use has this special knowledge about `Collection.toArray()` anyway,
+     * so in our implementation code, we can rely on that. That's why the expression below
+     * type-checks.
+     */
+    return super.toArray();
   }
 
-  @Override
-  @CanIgnoreReturnValue
-  public boolean remove(Object object) {
-    return delegate().remove(checkNotNull(object));
-  }
-
-  // TODO(kak): Do we want to checkNotNull each element in containsAll, removeAll, and retainAll?
-
   private static final long serialVersionUID = 0L;
 }
diff --git a/guava/src/com/google/common/collect/ExplicitOrdering.java b/guava/src/com/google/common/collect/ExplicitOrdering.java
index bf700d1be0ab..695903654481 100644
--- a/guava/src/com/google/common/collect/ExplicitOrdering.java
+++ b/guava/src/com/google/common/collect/ExplicitOrdering.java
@@ -19,6 +19,7 @@
 import com.google.common.annotations.GwtCompatible;
 import java.io.Serializable;
 import java.util.List;
+import javax.annotation.CheckForNull;
 import org.checkerframework.checker.nullness.qual.Nullable;
 import org.checkerframework.dataflow.qual.Pure;
 import org.checkerframework.framework.qual.AnnotatedFor;
@@ -26,6 +27,7 @@
 /** An ordering that compares objects according to a given order. */
 @AnnotatedFor({"nullness"})
 @GwtCompatible(serializable = true)
+@ElementTypesAreNonnullByDefault
 final class ExplicitOrdering<T> extends Ordering<T> implements Serializable {
   final ImmutableMap<T, Integer> rankMap;
 
@@ -53,7 +55,7 @@ private int rank(T value) {
 
   @Pure
   @Override
-  public boolean equals(@Nullable Object object) {
+  public boolean equals(@CheckForNull Object object) {
     if (object instanceof ExplicitOrdering) {
       ExplicitOrdering<?> that = (ExplicitOrdering<?>) object;
       return this.rankMap.equals(that.rankMap);
diff --git a/guava/src/com/google/common/collect/FilteredEntryMultimap.java b/guava/src/com/google/common/collect/FilteredEntryMultimap.java
index ced909a2120b..de946a215f42 100644
--- a/guava/src/com/google/common/collect/FilteredEntryMultimap.java
+++ b/guava/src/com/google/common/collect/FilteredEntryMultimap.java
@@ -33,6 +33,7 @@
 import java.util.Map;
 import java.util.Map.Entry;
 import java.util.Set;
+import javax.annotation.CheckForNull;
 import org.checkerframework.checker.nullness.qual.Nullable;
 
 /**
@@ -42,7 +43,9 @@
  * @author Louis Wasserman
  */
 @GwtCompatible
-class FilteredEntryMultimap<K, V> extends AbstractMultimap<K, V> implements FilteredMultimap<K, V> {
+@ElementTypesAreNonnullByDefault
+class FilteredEntryMultimap<K extends @Nullable Object, V extends @Nullable Object>
+    extends AbstractMultimap<K, V> implements FilteredMultimap<K, V> {
   final Multimap<K, V> unfiltered;
   final Predicate<? super Entry<K, V>> predicate;
 
@@ -66,24 +69,24 @@ public int size() {
     return entries().size();
   }
 
-  private boolean satisfies(K key, V value) {
+  private boolean satisfies(@ParametricNullness K key, @ParametricNullness V value) {
     return predicate.apply(Maps.immutableEntry(key, value));
   }
 
   final class ValuePredicate implements Predicate<V> {
-    private final K key;
+    @ParametricNullness private final K key;
 
-    ValuePredicate(K key) {
+    ValuePredicate(@ParametricNullness K key) {
       this.key = key;
     }
 
     @Override
-    public boolean apply(@Nullable V value) {
+    public boolean apply(@ParametricNullness V value) {
       return satisfies(key, value);
     }
   }
 
-  static <E> Collection<E> filterCollection(
+  static <E extends @Nullable Object> Collection<E> filterCollection(
       Collection<E> collection, Predicate<? super E> predicate) {
     if (collection instanceof Set) {
       return Sets.filter((Set<E>) collection, predicate);
@@ -93,12 +96,12 @@ static <E> Collection<E> filterCollection(
   }
 
   @Override
-  public boolean containsKey(@Nullable Object key) {
+  public boolean containsKey(@CheckForNull Object key) {
     return asMap().get(key) != null;
   }
 
   @Override
-  public Collection<V> removeAll(@Nullable Object key) {
+  public Collection<V> removeAll(@CheckForNull Object key) {
     return MoreObjects.firstNonNull(asMap().remove(key), unmodifiableEmptyCollection());
   }
 
@@ -115,7 +118,7 @@ public void clear() {
   }
 
   @Override
-  public Collection<V> get(final K key) {
+  public Collection<V> get(@ParametricNullness K key) {
     return filterCollection(unfiltered.get(key), new ValuePredicate(key));
   }
 
@@ -166,7 +169,7 @@ boolean removeEntriesIf(Predicate<? super Entry<K, Collection<V>>> predicate) {
   @WeakOuter
   class AsMap extends ViewCachingAbstractMap<K, Collection<V>> {
     @Override
-    public boolean containsKey(@Nullable Object key) {
+    public boolean containsKey(@CheckForNull Object key) {
       return get(key) != null;
     }
 
@@ -176,7 +179,8 @@ public void clear() {
     }
 
     @Override
-    public Collection<V> get(@Nullable Object key) {
+    @CheckForNull
+    public Collection<V> get(@CheckForNull Object key) {
       Collection<V> result = unfiltered.asMap().get(key);
       if (result == null) {
         return null;
@@ -188,7 +192,8 @@ public Collection<V> get(@Nullable Object key) {
     }
 
     @Override
-    public Collection<V> remove(@Nullable Object key) {
+    @CheckForNull
+    public Collection<V> remove(@CheckForNull Object key) {
       Collection<V> collection = unfiltered.asMap().get(key);
       if (collection == null) {
         return null;
@@ -232,7 +237,7 @@ public boolean retainAll(Collection<?> c) {
         }
 
         @Override
-        public boolean remove(@Nullable Object o) {
+        public boolean remove(@CheckForNull Object o) {
           return AsMap.this.remove(o) != null;
         }
       }
@@ -255,6 +260,7 @@ public Iterator<Entry<K, Collection<V>>> iterator() {
                 unfiltered.asMap().entrySet().iterator();
 
             @Override
+            @CheckForNull
             protected Entry<K, Collection<V>> computeNext() {
               while (backingIterator.hasNext()) {
                 Entry<K, Collection<V>> entry = backingIterator.next();
@@ -297,7 +303,7 @@ class ValuesImpl extends Maps.Values<K, Collection<V>> {
         }
 
         @Override
-        public boolean remove(@Nullable Object o) {
+        public boolean remove(@CheckForNull Object o) {
           if (o instanceof Collection) {
             Collection<?> c = (Collection<?>) o;
             Iterator<Entry<K, Collection<V>>> entryIterator =
@@ -346,7 +352,7 @@ class Keys extends Multimaps.Keys<K, V> {
     }
 
     @Override
-    public int remove(@Nullable Object key, int occurrences) {
+    public int remove(@CheckForNull Object key, int occurrences) {
       checkNonnegative(occurrences, "occurrences");
       if (occurrences == 0) {
         return count(key);
@@ -390,15 +396,11 @@ public int size() {
           return FilteredEntryMultimap.this.keySet().size();
         }
 
-        private boolean removeEntriesIf(final Predicate<? super Multiset.Entry<K>> predicate) {
+        private boolean removeEntriesIf(Predicate<? super Multiset.Entry<K>> predicate) {
           return FilteredEntryMultimap.this.removeEntriesIf(
-              new Predicate<Map.Entry<K, Collection<V>>>() {
-                @Override
-                public boolean apply(Map.Entry<K, Collection<V>> entry) {
-                  return predicate.apply(
-                      Multisets.immutableEntry(entry.getKey(), entry.getValue().size()));
-                }
-              });
+              (Map.Entry<K, Collection<V>> entry) ->
+                  predicate.apply(
+                      Multisets.immutableEntry(entry.getKey(), entry.getValue().size())));
         }
 
         @Override
diff --git a/guava/src/com/google/common/collect/FilteredEntrySetMultimap.java b/guava/src/com/google/common/collect/FilteredEntrySetMultimap.java
index 94740a4cf1a6..20413f8c4096 100644
--- a/guava/src/com/google/common/collect/FilteredEntrySetMultimap.java
+++ b/guava/src/com/google/common/collect/FilteredEntrySetMultimap.java
@@ -20,6 +20,8 @@
 import com.google.common.base.Predicate;
 import java.util.Map.Entry;
 import java.util.Set;
+import javax.annotation.CheckForNull;
+import org.checkerframework.checker.nullness.qual.Nullable;
 
 /**
  * Implementation of {@link Multimaps#filterEntries(SetMultimap, Predicate)}.
@@ -27,8 +29,9 @@
  * @author Louis Wasserman
  */
 @GwtCompatible
-final class FilteredEntrySetMultimap<K, V> extends FilteredEntryMultimap<K, V>
-    implements FilteredSetMultimap<K, V> {
+@ElementTypesAreNonnullByDefault
+final class FilteredEntrySetMultimap<K extends @Nullable Object, V extends @Nullable Object>
+    extends FilteredEntryMultimap<K, V> implements FilteredSetMultimap<K, V> {
 
   FilteredEntrySetMultimap(SetMultimap<K, V> unfiltered, Predicate<? super Entry<K, V>> predicate) {
     super(unfiltered, predicate);
@@ -40,17 +43,17 @@ public SetMultimap<K, V> unfiltered() {
   }
 
   @Override
-  public Set<V> get(K key) {
+  public Set<V> get(@ParametricNullness K key) {
     return (Set<V>) super.get(key);
   }
 
   @Override
-  public Set<V> removeAll(Object key) {
+  public Set<V> removeAll(@CheckForNull Object key) {
     return (Set<V>) super.removeAll(key);
   }
 
   @Override
-  public Set<V> replaceValues(K key, Iterable<? extends V> values) {
+  public Set<V> replaceValues(@ParametricNullness K key, Iterable<? extends V> values) {
     return (Set<V>) super.replaceValues(key, values);
   }
 
diff --git a/guava/src/com/google/common/collect/FilteredKeyListMultimap.java b/guava/src/com/google/common/collect/FilteredKeyListMultimap.java
index 8de9ed426042..c82c8daf770d 100644
--- a/guava/src/com/google/common/collect/FilteredKeyListMultimap.java
+++ b/guava/src/com/google/common/collect/FilteredKeyListMultimap.java
@@ -19,6 +19,7 @@
 import com.google.common.annotations.GwtCompatible;
 import com.google.common.base.Predicate;
 import java.util.List;
+import javax.annotation.CheckForNull;
 import org.checkerframework.checker.nullness.qual.Nullable;
 
 /**
@@ -27,8 +28,9 @@
  * @author Louis Wasserman
  */
 @GwtCompatible
-final class FilteredKeyListMultimap<K, V> extends FilteredKeyMultimap<K, V>
-    implements ListMultimap<K, V> {
+@ElementTypesAreNonnullByDefault
+final class FilteredKeyListMultimap<K extends @Nullable Object, V extends @Nullable Object>
+    extends FilteredKeyMultimap<K, V> implements ListMultimap<K, V> {
   FilteredKeyListMultimap(ListMultimap<K, V> unfiltered, Predicate<? super K> keyPredicate) {
     super(unfiltered, keyPredicate);
   }
@@ -39,17 +41,17 @@ public ListMultimap<K, V> unfiltered() {
   }
 
   @Override
-  public List<V> get(K key) {
+  public List<V> get(@ParametricNullness K key) {
     return (List<V>) super.get(key);
   }
 
   @Override
-  public List<V> removeAll(@Nullable Object key) {
+  public List<V> removeAll(@CheckForNull Object key) {
     return (List<V>) super.removeAll(key);
   }
 
   @Override
-  public List<V> replaceValues(K key, Iterable<? extends V> values) {
+  public List<V> replaceValues(@ParametricNullness K key, Iterable<? extends V> values) {
     return (List<V>) super.replaceValues(key, values);
   }
 }
diff --git a/guava/src/com/google/common/collect/FilteredKeyMultimap.java b/guava/src/com/google/common/collect/FilteredKeyMultimap.java
index 12456b3891f7..68fad75b1445 100644
--- a/guava/src/com/google/common/collect/FilteredKeyMultimap.java
+++ b/guava/src/com/google/common/collect/FilteredKeyMultimap.java
@@ -16,6 +16,8 @@
 
 import static com.google.common.base.Preconditions.checkNotNull;
 import static com.google.common.base.Preconditions.checkPositionIndex;
+import static java.util.Collections.emptyList;
+import static java.util.Collections.emptySet;
 
 import com.google.common.annotations.GwtCompatible;
 import com.google.common.base.Predicate;
@@ -28,6 +30,7 @@
 import java.util.Map;
 import java.util.Map.Entry;
 import java.util.Set;
+import javax.annotation.CheckForNull;
 import org.checkerframework.checker.nullness.qual.Nullable;
 
 /**
@@ -36,7 +39,9 @@
  * @author Louis Wasserman
  */
 @GwtCompatible
-class FilteredKeyMultimap<K, V> extends AbstractMultimap<K, V> implements FilteredMultimap<K, V> {
+@ElementTypesAreNonnullByDefault
+class FilteredKeyMultimap<K extends @Nullable Object, V extends @Nullable Object>
+    extends AbstractMultimap<K, V> implements FilteredMultimap<K, V> {
   final Multimap<K, V> unfiltered;
   final Predicate<? super K> keyPredicate;
 
@@ -65,7 +70,7 @@ public int size() {
   }
 
   @Override
-  public boolean containsKey(@Nullable Object key) {
+  public boolean containsKey(@CheckForNull Object key) {
     if (unfiltered.containsKey(key)) {
       @SuppressWarnings("unchecked") // k is equal to a K, if not one itself
       K k = (K) key;
@@ -75,15 +80,15 @@ public boolean containsKey(@Nullable Object key) {
   }
 
   @Override
-  public Collection<V> removeAll(Object key) {
+  public Collection<V> removeAll(@CheckForNull Object key) {
     return containsKey(key) ? unfiltered.removeAll(key) : unmodifiableEmptyCollection();
   }
 
   Collection<V> unmodifiableEmptyCollection() {
     if (unfiltered instanceof SetMultimap) {
-      return ImmutableSet.of();
+      return emptySet();
     } else {
-      return ImmutableList.of();
+      return emptyList();
     }
   }
 
@@ -98,7 +103,7 @@ Set<K> createKeySet() {
   }
 
   @Override
-  public Collection<V> get(K key) {
+  public Collection<V> get(@ParametricNullness K key) {
     if (keyPredicate.apply(key)) {
       return unfiltered.get(key);
     } else if (unfiltered instanceof SetMultimap) {
@@ -108,15 +113,16 @@ public Collection<V> get(K key) {
     }
   }
 
-  static class AddRejectingSet<K, V> extends ForwardingSet<V> {
-    final K key;
+  static class AddRejectingSet<K extends @Nullable Object, V extends @Nullable Object>
+      extends ForwardingSet<V> {
+    @ParametricNullness final K key;
 
-    AddRejectingSet(K key) {
+    AddRejectingSet(@ParametricNullness K key) {
       this.key = key;
     }
 
     @Override
-    public boolean add(V element) {
+    public boolean add(@ParametricNullness V element) {
       throw new IllegalArgumentException("Key does not satisfy predicate: " + key);
     }
 
@@ -132,21 +138,22 @@ protected Set<V> delegate() {
     }
   }
 
-  static class AddRejectingList<K, V> extends ForwardingList<V> {
-    final K key;
+  static class AddRejectingList<K extends @Nullable Object, V extends @Nullable Object>
+      extends ForwardingList<V> {
+    @ParametricNullness final K key;
 
-    AddRejectingList(K key) {
+    AddRejectingList(@ParametricNullness K key) {
       this.key = key;
     }
 
     @Override
-    public boolean add(V v) {
+    public boolean add(@ParametricNullness V v) {
       add(0, v);
       return true;
     }
 
     @Override
-    public void add(int index, V element) {
+    public void add(int index, @ParametricNullness V element) {
       checkPositionIndex(index, 0);
       throw new IllegalArgumentException("Key does not satisfy predicate: " + key);
     }
@@ -190,7 +197,7 @@ protected Collection<Entry<K, V>> delegate() {
 
     @Override
     @SuppressWarnings("unchecked")
-    public boolean remove(@Nullable Object o) {
+    public boolean remove(@CheckForNull Object o) {
       if (o instanceof Entry) {
         Entry<?, ?> entry = (Entry<?, ?>) o;
         if (unfiltered.containsKey(entry.getKey())
diff --git a/guava/src/com/google/common/collect/FilteredKeySetMultimap.java b/guava/src/com/google/common/collect/FilteredKeySetMultimap.java
index f6fb61d58830..e492a5c1dea9 100644
--- a/guava/src/com/google/common/collect/FilteredKeySetMultimap.java
+++ b/guava/src/com/google/common/collect/FilteredKeySetMultimap.java
@@ -20,6 +20,7 @@
 import com.google.common.base.Predicate;
 import java.util.Map.Entry;
 import java.util.Set;
+import javax.annotation.CheckForNull;
 import org.checkerframework.checker.nullness.qual.Nullable;
 
 /**
@@ -28,8 +29,9 @@
  * @author Louis Wasserman
  */
 @GwtCompatible
-final class FilteredKeySetMultimap<K, V> extends FilteredKeyMultimap<K, V>
-    implements FilteredSetMultimap<K, V> {
+@ElementTypesAreNonnullByDefault
+final class FilteredKeySetMultimap<K extends @Nullable Object, V extends @Nullable Object>
+    extends FilteredKeyMultimap<K, V> implements FilteredSetMultimap<K, V> {
 
   FilteredKeySetMultimap(SetMultimap<K, V> unfiltered, Predicate<? super K> keyPredicate) {
     super(unfiltered, keyPredicate);
@@ -41,17 +43,17 @@ public SetMultimap<K, V> unfiltered() {
   }
 
   @Override
-  public Set<V> get(K key) {
+  public Set<V> get(@ParametricNullness K key) {
     return (Set<V>) super.get(key);
   }
 
   @Override
-  public Set<V> removeAll(Object key) {
+  public Set<V> removeAll(@CheckForNull Object key) {
     return (Set<V>) super.removeAll(key);
   }
 
   @Override
-  public Set<V> replaceValues(K key, Iterable<? extends V> values) {
+  public Set<V> replaceValues(@ParametricNullness K key, Iterable<? extends V> values) {
     return (Set<V>) super.replaceValues(key, values);
   }
 
@@ -72,7 +74,7 @@ public int hashCode() {
     }
 
     @Override
-    public boolean equals(@Nullable Object o) {
+    public boolean equals(@CheckForNull Object o) {
       return Sets.equalsImpl(this, o);
     }
   }
diff --git a/guava/src/com/google/common/collect/FilteredMultimap.java b/guava/src/com/google/common/collect/FilteredMultimap.java
index ef5ed4ab26f3..4e1fa066f80b 100644
--- a/guava/src/com/google/common/collect/FilteredMultimap.java
+++ b/guava/src/com/google/common/collect/FilteredMultimap.java
@@ -19,6 +19,7 @@
 import com.google.common.annotations.GwtCompatible;
 import com.google.common.base.Predicate;
 import java.util.Map.Entry;
+import org.checkerframework.checker.nullness.qual.Nullable;
 
 /**
  * An interface for all filtered multimap types.
@@ -26,7 +27,9 @@
  * @author Louis Wasserman
  */
 @GwtCompatible
-interface FilteredMultimap<K, V> extends Multimap<K, V> {
+@ElementTypesAreNonnullByDefault
+interface FilteredMultimap<K extends @Nullable Object, V extends @Nullable Object>
+    extends Multimap<K, V> {
   Multimap<K, V> unfiltered();
 
   Predicate<? super Entry<K, V>> entryPredicate();
diff --git a/guava/src/com/google/common/collect/FilteredMultimapValues.java b/guava/src/com/google/common/collect/FilteredMultimapValues.java
index 7e3d25707855..ecbfab2a1d11 100644
--- a/guava/src/com/google/common/collect/FilteredMultimapValues.java
+++ b/guava/src/com/google/common/collect/FilteredMultimapValues.java
@@ -25,6 +25,7 @@
 import java.util.Collection;
 import java.util.Iterator;
 import java.util.Map.Entry;
+import javax.annotation.CheckForNull;
 import org.checkerframework.checker.nullness.qual.Nullable;
 
 /**
@@ -33,7 +34,9 @@
  * @author Louis Wasserman
  */
 @GwtCompatible
-final class FilteredMultimapValues<K, V> extends AbstractCollection<V> {
+@ElementTypesAreNonnullByDefault
+final class FilteredMultimapValues<K extends @Nullable Object, V extends @Nullable Object>
+    extends AbstractCollection<V> {
   @Weak private final FilteredMultimap<K, V> multimap;
 
   FilteredMultimapValues(FilteredMultimap<K, V> multimap) {
@@ -46,7 +49,7 @@ public Iterator<V> iterator() {
   }
 
   @Override
-  public boolean contains(@Nullable Object o) {
+  public boolean contains(@CheckForNull Object o) {
     return multimap.containsValue(o);
   }
 
@@ -56,7 +59,7 @@ public int size() {
   }
 
   @Override
-  public boolean remove(@Nullable Object o) {
+  public boolean remove(@CheckForNull Object o) {
     Predicate<? super Entry<K, V>> entryPredicate = multimap.entryPredicate();
     for (Iterator<Entry<K, V>> unfilteredItr = multimap.unfiltered().entries().iterator();
         unfilteredItr.hasNext(); ) {
diff --git a/guava/src/com/google/common/collect/FilteredSetMultimap.java b/guava/src/com/google/common/collect/FilteredSetMultimap.java
index a0a149fd7d5b..8e2ff7c0c1a6 100644
--- a/guava/src/com/google/common/collect/FilteredSetMultimap.java
+++ b/guava/src/com/google/common/collect/FilteredSetMultimap.java
@@ -17,6 +17,7 @@
 package com.google.common.collect;
 
 import com.google.common.annotations.GwtCompatible;
+import org.checkerframework.checker.nullness.qual.Nullable;
 
 /**
  * A supertype for filtered {@link SetMultimap} implementations.
@@ -24,7 +25,9 @@
  * @author Louis Wasserman
  */
 @GwtCompatible
-interface FilteredSetMultimap<K, V> extends FilteredMultimap<K, V>, SetMultimap<K, V> {
+@ElementTypesAreNonnullByDefault
+interface FilteredSetMultimap<K extends @Nullable Object, V extends @Nullable Object>
+    extends FilteredMultimap<K, V>, SetMultimap<K, V> {
   @Override
   SetMultimap<K, V> unfiltered();
 }
diff --git a/guava/src/com/google/common/collect/FluentIterable.java b/guava/src/com/google/common/collect/FluentIterable.java
index a15bcdd7cb63..11bda3bde95f 100644
--- a/guava/src/com/google/common/collect/FluentIterable.java
+++ b/guava/src/com/google/common/collect/FluentIterable.java
@@ -24,13 +24,16 @@
 import com.google.common.base.Optional;
 import com.google.common.base.Predicate;
 import com.google.errorprone.annotations.CanIgnoreReturnValue;
+import com.google.errorprone.annotations.InlineMe;
 import java.util.Arrays;
 import java.util.Collection;
+import java.util.Collections;
 import java.util.Comparator;
 import java.util.Iterator;
 import java.util.List;
 import java.util.SortedSet;
 import java.util.stream.Stream;
+import javax.annotation.CheckForNull;
 import org.checkerframework.checker.nullness.qual.Nullable;
 
 /**
@@ -106,11 +109,12 @@
  * @since 12.0
  */
 @GwtCompatible(emulated = true)
-public abstract class FluentIterable<E> implements Iterable<E> {
+@ElementTypesAreNonnullByDefault
+public abstract class FluentIterable<E extends @Nullable Object> implements Iterable<E> {
   // We store 'iterable' and use it instead of 'this' to allow Iterables to perform instanceof
   // checks on the _original_ iterable when FluentIterable.from is used.
   // To avoid a self retain cycle under j2objc, we store Optional.absent() instead of
-  // Optional.of(this). To access the iterator delegate, call #getDelegate(), which converts to
+  // Optional.of(this). To access the delegate iterable, call #getDelegate(), which converts to
   // absent() back to 'this'.
   private final Optional<Iterable<E>> iterableDelegate;
 
@@ -120,8 +124,7 @@ protected FluentIterable() {
   }
 
   FluentIterable(Iterable<E> iterable) {
-    checkNotNull(iterable);
-    this.iterableDelegate = Optional.fromNullable(this != iterable ? iterable : null);
+    this.iterableDelegate = Optional.of(iterable);
   }
 
   private Iterable<E> getDelegate() {
@@ -135,7 +138,7 @@ private Iterable<E> getDelegate() {
    * <p><b>{@code Stream} equivalent:</b> {@link Collection#stream} if {@code iterable} is a {@link
    * Collection}; {@link Streams#stream(Iterable)} otherwise.
    */
-  public static <E> FluentIterable<E> from(final Iterable<E> iterable) {
+  public static <E extends @Nullable Object> FluentIterable<E> from(final Iterable<E> iterable) {
     return (iterable instanceof FluentIterable)
         ? (FluentIterable<E>) iterable
         : new FluentIterable<E>(iterable) {
@@ -157,7 +160,7 @@ public Iterator<E> iterator() {
    * @since 20.0 (since 18.0 as an overload of {@code of})
    */
   @Beta
-  public static <E> FluentIterable<E> from(E[] elements) {
+  public static <E extends @Nullable Object> FluentIterable<E> from(E[] elements) {
     return from(Arrays.asList(elements));
   }
 
@@ -170,7 +173,10 @@ public static <E> FluentIterable<E> from(E[] elements) {
    *     FluentIterable}
    */
   @Deprecated
-  public static <E> FluentIterable<E> from(FluentIterable<E> iterable) {
+  @InlineMe(
+      replacement = "checkNotNull(iterable)",
+      staticImports = {"com.google.common.base.Preconditions.checkNotNull"})
+  public static <E extends @Nullable Object> FluentIterable<E> from(FluentIterable<E> iterable) {
     return checkNotNull(iterable);
   }
 
@@ -187,7 +193,8 @@ public static <E> FluentIterable<E> from(FluentIterable<E> iterable) {
    * @since 20.0
    */
   @Beta
-  public static <T> FluentIterable<T> concat(Iterable<? extends T> a, Iterable<? extends T> b) {
+  public static <T extends @Nullable Object> FluentIterable<T> concat(
+      Iterable<? extends T> a, Iterable<? extends T> b) {
     return concatNoDefensiveCopy(a, b);
   }
 
@@ -205,7 +212,7 @@ public static <T> FluentIterable<T> concat(Iterable<? extends T> a, Iterable<? e
    * @since 20.0
    */
   @Beta
-  public static <T> FluentIterable<T> concat(
+  public static <T extends @Nullable Object> FluentIterable<T> concat(
       Iterable<? extends T> a, Iterable<? extends T> b, Iterable<? extends T> c) {
     return concatNoDefensiveCopy(a, b, c);
   }
@@ -225,7 +232,7 @@ public static <T> FluentIterable<T> concat(
    * @since 20.0
    */
   @Beta
-  public static <T> FluentIterable<T> concat(
+  public static <T extends @Nullable Object> FluentIterable<T> concat(
       Iterable<? extends T> a,
       Iterable<? extends T> b,
       Iterable<? extends T> c,
@@ -249,7 +256,8 @@ public static <T> FluentIterable<T> concat(
    * @since 20.0
    */
   @Beta
-  public static <T> FluentIterable<T> concat(Iterable<? extends T>... inputs) {
+  public static <T extends @Nullable Object> FluentIterable<T> concat(
+      Iterable<? extends T>... inputs) {
     return concatNoDefensiveCopy(Arrays.copyOf(inputs, inputs.length));
   }
 
@@ -268,7 +276,7 @@ public static <T> FluentIterable<T> concat(Iterable<? extends T>... inputs) {
    * @since 20.0
    */
   @Beta
-  public static <T> FluentIterable<T> concat(
+  public static <T extends @Nullable Object> FluentIterable<T> concat(
       final Iterable<? extends Iterable<? extends T>> inputs) {
     checkNotNull(inputs);
     return new FluentIterable<T>() {
@@ -280,7 +288,7 @@ public Iterator<T> iterator() {
   }
 
   /** Concatenates a varargs array of iterables without making a defensive copy of the array. */
-  private static <T> FluentIterable<T> concatNoDefensiveCopy(
+  private static <T extends @Nullable Object> FluentIterable<T> concatNoDefensiveCopy(
       final Iterable<? extends T>... inputs) {
     for (Iterable<? extends T> input : inputs) {
       checkNotNull(input);
@@ -308,8 +316,8 @@ public Iterator<? extends T> get(int i) {
    * @since 20.0
    */
   @Beta
-  public static <E> FluentIterable<E> of() {
-    return FluentIterable.from(ImmutableList.<E>of());
+  public static <E extends @Nullable Object> FluentIterable<E> of() {
+    return FluentIterable.from(Collections.<E>emptyList());
   }
 
   /**
@@ -321,7 +329,8 @@ public static <E> FluentIterable<E> of() {
    * @since 20.0
    */
   @Beta
-  public static <E> FluentIterable<E> of(@Nullable E element, E... elements) {
+  public static <E extends @Nullable Object> FluentIterable<E> of(
+      @ParametricNullness E element, E... elements) {
     return from(Lists.asList(element, elements));
   }
 
@@ -352,7 +361,7 @@ public final int size() {
    *
    * <p><b>{@code Stream} equivalent:</b> {@code stream.anyMatch(Predicate.isEqual(target))}.
    */
-  public final boolean contains(@Nullable Object target) {
+  public final boolean contains(@CheckForNull Object target) {
     return Iterables.contains(getDelegate(), target);
   }
 
@@ -462,6 +471,7 @@ public final boolean allMatch(Predicate<? super E> predicate) {
    *
    * <p><b>{@code Stream} equivalent:</b> {@code stream.filter(predicate).findFirst()}.
    */
+  @SuppressWarnings("nullness") // Unsafe, but we can't do much about it now.
   public final Optional<E> firstMatch(Predicate<? super E> predicate) {
     return Iterables.tryFind(getDelegate(), predicate);
   }
@@ -476,7 +486,8 @@ public final Optional<E> firstMatch(Predicate<? super E> predicate) {
    *
    * <p><b>{@code Stream} equivalent:</b> {@link Stream#map}.
    */
-  public final <T> FluentIterable<T> transform(Function<? super E, T> function) {
+  public final <T extends @Nullable Object> FluentIterable<T> transform(
+      Function<? super E, T> function) {
     return from(Iterables.transform(getDelegate(), function));
   }
 
@@ -493,7 +504,7 @@ public final <T> FluentIterable<T> transform(Function<? super E, T> function) {
    *
    * @since 13.0 (required {@code Function<E, Iterable<T>>} until 14.0)
    */
-  public <T> FluentIterable<T> transformAndConcat(
+  public <T extends @Nullable Object> FluentIterable<T> transformAndConcat(
       Function<? super E, ? extends Iterable<? extends T>> function) {
     return FluentIterable.concat(transform(function));
   }
@@ -508,6 +519,7 @@ public <T> FluentIterable<T> transformAndConcat(
    * @throws NullPointerException if the first element is null; if this is a possibility, use {@code
    *     iterator().next()} or {@link Iterables#getFirst} instead.
    */
+  @SuppressWarnings("nullness") // Unsafe, but we can't do much about it now.
   public final Optional<E> first() {
     Iterator<E> iterator = getDelegate().iterator();
     return iterator.hasNext() ? Optional.of(iterator.next()) : Optional.<E>absent();
@@ -524,6 +536,7 @@ public final Optional<E> first() {
    * @throws NullPointerException if the last element is null; if this is a possibility, use {@link
    *     Iterables#getLast} instead.
    */
+  @SuppressWarnings("nullness") // Unsafe, but we can't do much about it now.
   public final Optional<E> last() {
     // Iterables#getLast was inlined here so we don't have to throw/catch a NSEE
 
@@ -613,6 +626,7 @@ public final boolean isEmpty() {
    * @throws NullPointerException if any element is {@code null}
    * @since 14.0 (since 12.0 as {@code toImmutableList()}).
    */
+  @SuppressWarnings("nullness") // Unsafe, but we can't do much about it now.
   public final ImmutableList<E> toList() {
     return ImmutableList.copyOf(getDelegate());
   }
@@ -629,6 +643,7 @@ public final ImmutableList<E> toList() {
    * @throws NullPointerException if any element of this iterable is {@code null}
    * @since 14.0 (since 13.0 as {@code toSortedImmutableList()}).
    */
+  @SuppressWarnings("nullness") // Unsafe, but we can't do much about it now.
   public final ImmutableList<E> toSortedList(Comparator<? super E> comparator) {
     return Ordering.from(comparator).immutableSortedCopy(getDelegate());
   }
@@ -643,6 +658,7 @@ public final ImmutableList<E> toSortedList(Comparator<? super E> comparator) {
    * @throws NullPointerException if any element is {@code null}
    * @since 14.0 (since 12.0 as {@code toImmutableSet()}).
    */
+  @SuppressWarnings("nullness") // Unsafe, but we can't do much about it now.
   public final ImmutableSet<E> toSet() {
     return ImmutableSet.copyOf(getDelegate());
   }
@@ -660,6 +676,7 @@ public final ImmutableSet<E> toSet() {
    * @throws NullPointerException if any element of this iterable is {@code null}
    * @since 14.0 (since 12.0 as {@code toImmutableSortedSet()}).
    */
+  @SuppressWarnings("nullness") // Unsafe, but we can't do much about it now.
   public final ImmutableSortedSet<E> toSortedSet(Comparator<? super E> comparator) {
     return ImmutableSortedSet.copyOf(comparator, getDelegate());
   }
@@ -673,6 +690,7 @@ public final ImmutableSortedSet<E> toSortedSet(Comparator<? super E> comparator)
    * @throws NullPointerException if any element is null
    * @since 19.0
    */
+  @SuppressWarnings("nullness") // Unsafe, but we can't do much about it now.
   public final ImmutableMultiset<E> toMultiset() {
     return ImmutableMultiset.copyOf(getDelegate());
   }
@@ -693,6 +711,7 @@ public final ImmutableMultiset<E> toMultiset() {
    *     valueFunction} produces {@code null} for any key
    * @since 14.0
    */
+  @SuppressWarnings("nullness") // Unsafe, but we can't do much about it now.
   public final <V> ImmutableMap<E, V> toMap(Function<? super E, V> valueFunction) {
     return Maps.toMap(getDelegate(), valueFunction);
   }
@@ -715,6 +734,7 @@ public final <V> ImmutableMap<E, V> toMap(Function<? super E, V> valueFunction)
    *     keyFunction} produces {@code null} for any key
    * @since 14.0
    */
+  @SuppressWarnings("nullness") // Unsafe, but we can't do much about it now.
   public final <K> ImmutableListMultimap<K, E> index(Function<? super E, K> keyFunction) {
     return Multimaps.index(getDelegate(), keyFunction);
   }
@@ -749,6 +769,7 @@ public final <K> ImmutableListMultimap<K, E> index(Function<? super E, K> keyFun
    *     keyFunction} produces {@code null} for any key
    * @since 14.0
    */
+  @SuppressWarnings("nullness") // Unsafe, but we can't do much about it now.
   public final <K> ImmutableMap<K, E> uniqueIndex(Function<? super E, K> keyFunction) {
     return Maps.uniqueIndex(getDelegate(), keyFunction);
   }
@@ -766,7 +787,15 @@ public final <K> ImmutableMap<K, E> uniqueIndex(Function<? super E, K> keyFuncti
    *     copied
    */
   @GwtIncompatible // Array.newArray(Class, int)
-  public final E[] toArray(Class<E> type) {
+  /*
+   * Both the declaration of our Class<E> parameter and its usage in a call to Iterables.toArray
+   * produce a nullness error: E may be a nullable type, and our nullness checker has Class's type
+   * parameter bounded to non-null types. To avoid that, we'd use Class<@Nonnull E> if we could.
+   * (Granted, this is only one of many nullness-checking problems that arise from letting
+   * FluentIterable support null elements, and most of the other produce outright unsoundness.)
+   */
+  @SuppressWarnings("nullness")
+  public final @Nullable E[] toArray(Class<E> type) {
     return Iterables.toArray(getDelegate(), type);
   }
 
@@ -822,7 +851,7 @@ public final String join(Joiner joiner) {
    * @throws IndexOutOfBoundsException if {@code position} is negative or greater than or equal to
    *     the size of this fluent iterable
    */
-  // TODO(kevinb): add @Nullable?
+  @ParametricNullness
   public final E get(int position) {
     return Iterables.get(getDelegate(), position);
   }
@@ -842,7 +871,8 @@ public final Stream<E> stream() {
   }
 
   /** Function that transforms {@code Iterable<E>} into a fluent iterable. */
-  private static class FromIterableFunction<E> implements Function<Iterable<E>, FluentIterable<E>> {
+  private static class FromIterableFunction<E extends @Nullable Object>
+      implements Function<Iterable<E>, FluentIterable<E>> {
     @Override
     public FluentIterable<E> apply(Iterable<E> fromObject) {
       return FluentIterable.from(fromObject);
diff --git a/guava/src/com/google/common/collect/ForwardingBlockingDeque.java b/guava/src/com/google/common/collect/ForwardingBlockingDeque.java
index 7d3895d01502..49d4bcf6c232 100644
--- a/guava/src/com/google/common/collect/ForwardingBlockingDeque.java
+++ b/guava/src/com/google/common/collect/ForwardingBlockingDeque.java
@@ -20,6 +20,7 @@
 import java.util.Collection;
 import java.util.concurrent.BlockingDeque;
 import java.util.concurrent.TimeUnit;
+import javax.annotation.CheckForNull;
 
 /**
  * A {@link BlockingDeque} which forwards all its method calls to another {@code BlockingDeque}.
@@ -46,6 +47,7 @@
  */
 @Deprecated
 @GwtIncompatible
+@ElementTypesAreNonnullByDefault
 public abstract class ForwardingBlockingDeque<E> extends ForwardingDeque<E>
     implements BlockingDeque<E> {
 
@@ -91,11 +93,13 @@ public E takeLast() throws InterruptedException {
   }
 
   @Override
+  @CheckForNull
   public E pollFirst(long timeout, TimeUnit unit) throws InterruptedException {
     return delegate().pollFirst(timeout, unit);
   }
 
   @Override
+  @CheckForNull
   public E pollLast(long timeout, TimeUnit unit) throws InterruptedException {
     return delegate().pollLast(timeout, unit);
   }
@@ -116,6 +120,7 @@ public E take() throws InterruptedException {
   }
 
   @Override
+  @CheckForNull
   public E poll(long timeout, TimeUnit unit) throws InterruptedException {
     return delegate().poll(timeout, unit);
   }
diff --git a/guava/src/com/google/common/collect/ForwardingCollection.java b/guava/src/com/google/common/collect/ForwardingCollection.java
index b34090a8be42..f8c7e86d4008 100644
--- a/guava/src/com/google/common/collect/ForwardingCollection.java
+++ b/guava/src/com/google/common/collect/ForwardingCollection.java
@@ -21,6 +21,7 @@
 import com.google.errorprone.annotations.CanIgnoreReturnValue;
 import java.util.Collection;
 import java.util.Iterator;
+import javax.annotation.CheckForNull;
 import org.checkerframework.checker.nullness.qual.Nullable;
 import org.checkerframework.dataflow.qual.Pure;
 import org.checkerframework.framework.qual.AnnotatedFor;
@@ -49,8 +50,9 @@
  */
 @AnnotatedFor({"nullness"})
 @GwtCompatible
-@SuppressWarnings("nullness:generic.argument")
-public abstract class ForwardingCollection<E> extends ForwardingObject implements Collection<E> {
+@ElementTypesAreNonnullByDefault
+public abstract class ForwardingCollection<E extends @Nullable Object> extends ForwardingObject
+    implements Collection<E> {
   // TODO(lowasser): identify places where thread safety is actually lost
 
   /** Constructor for use by subclasses. */
@@ -66,6 +68,7 @@ public Iterator<E> iterator() {
 
   @Pure
   @Override
+  @SuppressWarnings("index:override.return")
   public int size() {
     return delegate().size();
   }
@@ -84,20 +87,21 @@ public boolean isEmpty() {
 
   @Pure
   @Override
-  public boolean contains(@Nullable Object object) {
+  @SuppressWarnings("nullness:argument")
+  public boolean contains(@CheckForNull Object object) {
     return delegate().contains(object);
   }
 
   @CanIgnoreReturnValue
   @Override
-  public boolean add(E element) {
+  public boolean add(@ParametricNullness E element) {
     return delegate().add(element);
   }
 
   @CanIgnoreReturnValue
   @Override
-  @SuppressWarnings("nullness") // Suppressed due to the annotations on ConcurrentMap
-  public boolean remove(@Nullable Object object) {
+  @SuppressWarnings("nullness:argument")
+  public boolean remove(@CheckForNull Object object) {
     return delegate().remove(object);
   }
 
@@ -134,8 +138,8 @@ public void clear() {
 
   @CanIgnoreReturnValue
   @Override
-  @SuppressWarnings("nullness")
-  public <T> T[] toArray(T[] array) {
+  @SuppressWarnings("nullness") // b/192354773 in our checker affects toArray declarations
+  public <T extends @Nullable Object> T[] toArray(T[] array) {
     return delegate().toArray(array);
   }
 
@@ -146,7 +150,7 @@ public <T> T[] toArray(T[] array) {
    *
    * @since 7.0
    */
-  protected boolean standardContains(@Nullable Object object) {
+  protected boolean standardContains(@CheckForNull Object object) {
     return Iterators.contains(iterator(), object);
   }
 
@@ -178,7 +182,7 @@ protected boolean standardAddAll(Collection<? extends E> collection) {
    *
    * @since 7.0
    */
-  protected boolean standardRemove(@Nullable Object object) {
+  protected boolean standardRemove(@CheckForNull Object object) {
     Iterator<E> iterator = iterator();
     while (iterator.hasNext()) {
       if (Objects.equal(iterator.next(), object)) {
@@ -251,8 +255,8 @@ protected String standardToString() {
    *
    * @since 7.0
    */
-  protected Object[] standardToArray() {
-    Object[] newArray = new Object[size()];
+  protected @Nullable Object[] standardToArray() {
+    @Nullable Object[] newArray = new @Nullable Object[size()];
     return toArray(newArray);
   }
 
@@ -263,7 +267,7 @@ protected Object[] standardToArray() {
    *
    * @since 7.0
    */
-  protected <T> T[] standardToArray(T[] array) {
+  protected <T extends @Nullable Object> T[] standardToArray(T[] array) {
     return ObjectArrays.toArrayImpl(this, array);
   }
 }
diff --git a/guava/src/com/google/common/collect/ForwardingConcurrentMap.java b/guava/src/com/google/common/collect/ForwardingConcurrentMap.java
index b5c87dfa3cc8..2d8445e04ef9 100644
--- a/guava/src/com/google/common/collect/ForwardingConcurrentMap.java
+++ b/guava/src/com/google/common/collect/ForwardingConcurrentMap.java
@@ -19,6 +19,7 @@
 import com.google.common.annotations.GwtCompatible;
 import com.google.errorprone.annotations.CanIgnoreReturnValue;
 import java.util.concurrent.ConcurrentMap;
+import javax.annotation.CheckForNull;
 import org.checkerframework.checker.nullness.qual.Nullable;
 import org.checkerframework.framework.qual.AnnotatedFor;
 
@@ -39,7 +40,7 @@
  */
 @AnnotatedFor({"nullness"})
 @GwtCompatible
-@SuppressWarnings("nullness:generic.argument")
+@ElementTypesAreNonnullByDefault
 public abstract class ForwardingConcurrentMap<K, V> extends ForwardingMap<K, V>
     implements ConcurrentMap<K, V> {
 
@@ -47,22 +48,26 @@ public abstract class ForwardingConcurrentMap<K, V> extends ForwardingMap<K, V>
   protected ForwardingConcurrentMap() {}
 
   @Override
+  @SuppressWarnings("nullness:type.argument")
   protected abstract ConcurrentMap<K, V> delegate();
 
   @CanIgnoreReturnValue
   @Override
+  @CheckForNull
   public V putIfAbsent(K key, V value) {
     return delegate().putIfAbsent(key, value);
   }
 
   @CanIgnoreReturnValue
   @Override
-  public boolean remove(@Nullable Object key, @Nullable Object value) {
+  @SuppressWarnings("nullness:argument")
+  public boolean remove(@CheckForNull Object key, @CheckForNull Object value) {
     return delegate().remove(key, value);
   }
 
   @CanIgnoreReturnValue
   @Override
+  @CheckForNull
   public V replace(K key, V value) {
     return delegate().replace(key, value);
   }
diff --git a/guava/src/com/google/common/collect/ForwardingDeque.java b/guava/src/com/google/common/collect/ForwardingDeque.java
index 87ac71bd67ec..571535cab917 100644
--- a/guava/src/com/google/common/collect/ForwardingDeque.java
+++ b/guava/src/com/google/common/collect/ForwardingDeque.java
@@ -20,6 +20,8 @@
 import com.google.errorprone.annotations.CanIgnoreReturnValue;
 import java.util.Deque;
 import java.util.Iterator;
+import javax.annotation.CheckForNull;
+import org.checkerframework.checker.nullness.qual.Nullable;
 
 /**
  * A deque which forwards all its method calls to another deque. Subclasses should override one or
@@ -39,7 +41,9 @@
  * @since 12.0
  */
 @GwtIncompatible
-public abstract class ForwardingDeque<E> extends ForwardingQueue<E> implements Deque<E> {
+@ElementTypesAreNonnullByDefault
+public abstract class ForwardingDeque<E extends @Nullable Object> extends ForwardingQueue<E>
+    implements Deque<E> {
 
   /** Constructor for use by subclasses. */
   protected ForwardingDeque() {}
@@ -48,12 +52,12 @@ protected ForwardingDeque() {}
   protected abstract Deque<E> delegate();
 
   @Override
-  public void addFirst(E e) {
+  public void addFirst(@ParametricNullness E e) {
     delegate().addFirst(e);
   }
 
   @Override
-  public void addLast(E e) {
+  public void addLast(@ParametricNullness E e) {
     delegate().addLast(e);
   }
 
@@ -63,81 +67,90 @@ public Iterator<E> descendingIterator() {
   }
 
   @Override
+  @ParametricNullness
   public E getFirst() {
     return delegate().getFirst();
   }
 
   @Override
+  @ParametricNullness
   public E getLast() {
     return delegate().getLast();
   }
 
   @CanIgnoreReturnValue // TODO(cpovirk): Consider removing this?
   @Override
-  public boolean offerFirst(E e) {
+  public boolean offerFirst(@ParametricNullness E e) {
     return delegate().offerFirst(e);
   }
 
   @CanIgnoreReturnValue // TODO(cpovirk): Consider removing this?
   @Override
-  public boolean offerLast(E e) {
+  public boolean offerLast(@ParametricNullness E e) {
     return delegate().offerLast(e);
   }
 
   @Override
+  @CheckForNull
   public E peekFirst() {
     return delegate().peekFirst();
   }
 
   @Override
+  @CheckForNull
   public E peekLast() {
     return delegate().peekLast();
   }
 
   @CanIgnoreReturnValue // TODO(cpovirk): Consider removing this?
   @Override
+  @CheckForNull
   public E pollFirst() {
     return delegate().pollFirst();
   }
 
   @CanIgnoreReturnValue // TODO(cpovirk): Consider removing this?
   @Override
+  @CheckForNull
   public E pollLast() {
     return delegate().pollLast();
   }
 
   @CanIgnoreReturnValue
   @Override
+  @ParametricNullness
   public E pop() {
     return delegate().pop();
   }
 
   @Override
-  public void push(E e) {
+  public void push(@ParametricNullness E e) {
     delegate().push(e);
   }
 
   @CanIgnoreReturnValue
   @Override
+  @ParametricNullness
   public E removeFirst() {
     return delegate().removeFirst();
   }
 
   @CanIgnoreReturnValue
   @Override
+  @ParametricNullness
   public E removeLast() {
     return delegate().removeLast();
   }
 
   @CanIgnoreReturnValue
   @Override
-  public boolean removeFirstOccurrence(Object o) {
+  public boolean removeFirstOccurrence(@CheckForNull Object o) {
     return delegate().removeFirstOccurrence(o);
   }
 
   @CanIgnoreReturnValue
   @Override
-  public boolean removeLastOccurrence(Object o) {
+  public boolean removeLastOccurrence(@CheckForNull Object o) {
     return delegate().removeLastOccurrence(o);
   }
 }
diff --git a/guava/src/com/google/common/collect/ForwardingImmutableCollection.java b/guava/src/com/google/common/collect/ForwardingImmutableCollection.java
index c0b9c5e54d74..043fe5863593 100644
--- a/guava/src/com/google/common/collect/ForwardingImmutableCollection.java
+++ b/guava/src/com/google/common/collect/ForwardingImmutableCollection.java
@@ -24,6 +24,7 @@
  * @author Hayward Chan
  */
 @GwtCompatible(emulated = true)
+@ElementTypesAreNonnullByDefault
 class ForwardingImmutableCollection {
   private ForwardingImmutableCollection() {}
 }
diff --git a/guava/src/com/google/common/collect/ForwardingImmutableList.java b/guava/src/com/google/common/collect/ForwardingImmutableList.java
index 2b9092ea4c93..bd5480d589c4 100644
--- a/guava/src/com/google/common/collect/ForwardingImmutableList.java
+++ b/guava/src/com/google/common/collect/ForwardingImmutableList.java
@@ -24,6 +24,7 @@
  * @author Chris Povirk
  */
 @GwtCompatible(emulated = true)
+@ElementTypesAreNonnullByDefault
 abstract class ForwardingImmutableList<E> {
   private ForwardingImmutableList() {}
 }
diff --git a/guava/src/com/google/common/collect/ForwardingImmutableMap.java b/guava/src/com/google/common/collect/ForwardingImmutableMap.java
index a36715743f0a..22cc9ff8711c 100644
--- a/guava/src/com/google/common/collect/ForwardingImmutableMap.java
+++ b/guava/src/com/google/common/collect/ForwardingImmutableMap.java
@@ -24,6 +24,7 @@
  * @author Chris Povirk
  */
 @GwtCompatible(emulated = true)
+@ElementTypesAreNonnullByDefault
 abstract class ForwardingImmutableMap<K, V> {
   private ForwardingImmutableMap() {}
 }
diff --git a/guava/src/com/google/common/collect/ForwardingImmutableSet.java b/guava/src/com/google/common/collect/ForwardingImmutableSet.java
index c7d7bf6d778b..047d5fd32216 100644
--- a/guava/src/com/google/common/collect/ForwardingImmutableSet.java
+++ b/guava/src/com/google/common/collect/ForwardingImmutableSet.java
@@ -24,6 +24,7 @@
  * @author Chris Povirk
  */
 @GwtCompatible(emulated = true)
+@ElementTypesAreNonnullByDefault
 abstract class ForwardingImmutableSet<E> {
   private ForwardingImmutableSet() {}
 }
diff --git a/guava/src/com/google/common/collect/ForwardingIterator.java b/guava/src/com/google/common/collect/ForwardingIterator.java
index db33bc687ec5..ecc7f1b9ac1d 100644
--- a/guava/src/com/google/common/collect/ForwardingIterator.java
+++ b/guava/src/com/google/common/collect/ForwardingIterator.java
@@ -19,6 +19,7 @@
 import com.google.common.annotations.GwtCompatible;
 import com.google.errorprone.annotations.CanIgnoreReturnValue;
 import java.util.Iterator;
+import org.checkerframework.checker.nullness.qual.Nullable;
 import org.checkerframework.framework.qual.AnnotatedFor;
 
 /**
@@ -38,8 +39,9 @@
  */
 @AnnotatedFor({"nullness"})
 @GwtCompatible
-@SuppressWarnings("nullness:generic.argument")
-public abstract class ForwardingIterator<T> extends ForwardingObject implements Iterator<T> {
+@ElementTypesAreNonnullByDefault
+public abstract class ForwardingIterator<T extends @Nullable Object> extends ForwardingObject
+    implements Iterator<T> {
 
   /** Constructor for use by subclasses. */
   protected ForwardingIterator() {}
@@ -54,6 +56,7 @@ public boolean hasNext() {
 
   @CanIgnoreReturnValue
   @Override
+  @ParametricNullness
   public T next() {
     return delegate().next();
   }
diff --git a/guava/src/com/google/common/collect/ForwardingList.java b/guava/src/com/google/common/collect/ForwardingList.java
index aee4e7f1200e..13865bf50926 100644
--- a/guava/src/com/google/common/collect/ForwardingList.java
+++ b/guava/src/com/google/common/collect/ForwardingList.java
@@ -23,6 +23,7 @@
 import java.util.Iterator;
 import java.util.List;
 import java.util.ListIterator;
+import javax.annotation.CheckForNull;
 import org.checkerframework.checker.nullness.qual.Nullable;
 import org.checkerframework.dataflow.qual.Pure;
 import org.checkerframework.dataflow.qual.SideEffectFree;
@@ -55,8 +56,9 @@
  */
 @AnnotatedFor({"nullness"})
 @GwtCompatible
-@SuppressWarnings("nullness:generic.argument")
-public abstract class ForwardingList<E> extends ForwardingCollection<E> implements List<E> {
+@ElementTypesAreNonnullByDefault
+public abstract class ForwardingList<E extends @Nullable Object> extends ForwardingCollection<E>
+    implements List<E> {
   // TODO(lowasser): identify places where thread safety is actually lost
 
   /** Constructor for use by subclasses. */
@@ -66,7 +68,7 @@ protected ForwardingList() {}
   protected abstract List<E> delegate();
 
   @Override
-  public void add(int index, E element) {
+  public void add(int index, @ParametricNullness E element) {
     delegate().add(index, element);
   }
 
@@ -77,19 +79,22 @@ public boolean addAll(int index, Collection<? extends E> elements) {
   }
 
   @Override
+  @ParametricNullness
   public E get(int index) {
     return delegate().get(index);
   }
 
   @Pure
   @Override
-  public int indexOf(@Nullable Object element) {
+  @SuppressWarnings("nullness:argument")
+  public int indexOf(@CheckForNull Object element) {
     return delegate().indexOf(element);
   }
 
   @Pure
   @Override
-  public int lastIndexOf(@Nullable Object element) {
+  @SuppressWarnings("nullness:argument")
+  public int lastIndexOf(@CheckForNull Object element) {
     return delegate().lastIndexOf(element);
   }
 
@@ -105,13 +110,15 @@ public ListIterator<E> listIterator(int index) {
 
   @CanIgnoreReturnValue
   @Override
+  @ParametricNullness
   public E remove(int index) {
     return delegate().remove(index);
   }
 
   @CanIgnoreReturnValue
   @Override
-  public E set(int index, E element) {
+  @ParametricNullness
+  public E set(int index, @ParametricNullness E element) {
     return delegate().set(index, element);
   }
 
@@ -123,7 +130,7 @@ public List<E> subList(int fromIndex, int toIndex) {
 
   @Pure
   @Override
-  public boolean equals(@Nullable Object object) {
+  public boolean equals(@CheckForNull Object object) {
     return object == this || delegate().equals(object);
   }
 
@@ -140,7 +147,7 @@ public int hashCode() {
    *
    * @since 7.0
    */
-  protected boolean standardAdd(E element) {
+  protected boolean standardAdd(@ParametricNullness E element) {
     add(size(), element);
     return true;
   }
@@ -163,7 +170,7 @@ protected boolean standardAddAll(int index, Iterable<? extends E> elements) {
    *
    * @since 7.0
    */
-  protected int standardIndexOf(@Nullable Object element) {
+  protected int standardIndexOf(@CheckForNull Object element) {
     return Lists.indexOfImpl(this, element);
   }
 
@@ -174,7 +181,7 @@ protected int standardIndexOf(@Nullable Object element) {
    *
    * @since 7.0
    */
-  protected int standardLastIndexOf(@Nullable Object element) {
+  protected int standardLastIndexOf(@CheckForNull Object element) {
     return Lists.lastIndexOfImpl(this, element);
   }
 
@@ -232,7 +239,7 @@ protected List<E> standardSubList(int fromIndex, int toIndex) {
    * @since 7.0
    */
   @Beta
-  protected boolean standardEquals(@Nullable Object object) {
+  protected boolean standardEquals(@CheckForNull Object object) {
     return Lists.equalsImpl(this, object);
   }
 
diff --git a/guava/src/com/google/common/collect/ForwardingListIterator.java b/guava/src/com/google/common/collect/ForwardingListIterator.java
index 77b3275502b4..49a312216361 100644
--- a/guava/src/com/google/common/collect/ForwardingListIterator.java
+++ b/guava/src/com/google/common/collect/ForwardingListIterator.java
@@ -19,6 +19,7 @@
 import com.google.common.annotations.GwtCompatible;
 import com.google.errorprone.annotations.CanIgnoreReturnValue;
 import java.util.ListIterator;
+import org.checkerframework.checker.nullness.qual.Nullable;
 import org.checkerframework.framework.qual.AnnotatedFor;
 
 /**
@@ -38,9 +39,9 @@
  */
 @AnnotatedFor({"nullness"})
 @GwtCompatible
-@SuppressWarnings("nullness:generic.argument")
-public abstract class ForwardingListIterator<E> extends ForwardingIterator<E>
-    implements ListIterator<E> {
+@ElementTypesAreNonnullByDefault
+public abstract class ForwardingListIterator<E extends @Nullable Object>
+    extends ForwardingIterator<E> implements ListIterator<E> {
 
   /** Constructor for use by subclasses. */
   protected ForwardingListIterator() {}
@@ -49,7 +50,7 @@ protected ForwardingListIterator() {}
   protected abstract ListIterator<E> delegate();
 
   @Override
-  public void add(E element) {
+  public void add(@ParametricNullness E element) {
     delegate().add(element);
   }
 
@@ -59,23 +60,26 @@ public boolean hasPrevious() {
   }
 
   @Override
+  @SuppressWarnings("index:override.return")
   public int nextIndex() {
     return delegate().nextIndex();
   }
 
   @CanIgnoreReturnValue
   @Override
+  @ParametricNullness
   public E previous() {
     return delegate().previous();
   }
 
   @Override
+  @SuppressWarnings("index:override.return")
   public int previousIndex() {
     return delegate().previousIndex();
   }
 
   @Override
-  public void set(E element) {
+  public void set(@ParametricNullness E element) {
     delegate().set(element);
   }
 }
diff --git a/guava/src/com/google/common/collect/ForwardingListMultimap.java b/guava/src/com/google/common/collect/ForwardingListMultimap.java
index c67d56c47e43..11779c0bb826 100644
--- a/guava/src/com/google/common/collect/ForwardingListMultimap.java
+++ b/guava/src/com/google/common/collect/ForwardingListMultimap.java
@@ -19,6 +19,7 @@
 import com.google.common.annotations.GwtCompatible;
 import com.google.errorprone.annotations.CanIgnoreReturnValue;
 import java.util.List;
+import javax.annotation.CheckForNull;
 import org.checkerframework.checker.nullness.qual.Nullable;
 
 /**
@@ -34,8 +35,9 @@
  * @since 3.0
  */
 @GwtCompatible
-public abstract class ForwardingListMultimap<K, V> extends ForwardingMultimap<K, V>
-    implements ListMultimap<K, V> {
+@ElementTypesAreNonnullByDefault
+public abstract class ForwardingListMultimap<K extends @Nullable Object, V extends @Nullable Object>
+    extends ForwardingMultimap<K, V> implements ListMultimap<K, V> {
 
   /** Constructor for use by subclasses. */
   protected ForwardingListMultimap() {}
@@ -44,19 +46,19 @@ protected ForwardingListMultimap() {}
   protected abstract ListMultimap<K, V> delegate();
 
   @Override
-  public List<V> get(@Nullable K key) {
+  public List<V> get(@ParametricNullness K key) {
     return delegate().get(key);
   }
 
   @CanIgnoreReturnValue
   @Override
-  public List<V> removeAll(@Nullable Object key) {
+  public List<V> removeAll(@CheckForNull Object key) {
     return delegate().removeAll(key);
   }
 
   @CanIgnoreReturnValue
   @Override
-  public List<V> replaceValues(K key, Iterable<? extends V> values) {
+  public List<V> replaceValues(@ParametricNullness K key, Iterable<? extends V> values) {
     return delegate().replaceValues(key, values);
   }
 }
diff --git a/guava/src/com/google/common/collect/ForwardingMap.java b/guava/src/com/google/common/collect/ForwardingMap.java
index 067f6eb1d415..319027c4440c 100644
--- a/guava/src/com/google/common/collect/ForwardingMap.java
+++ b/guava/src/com/google/common/collect/ForwardingMap.java
@@ -24,6 +24,7 @@
 import java.util.Iterator;
 import java.util.Map;
 import java.util.Set;
+import javax.annotation.CheckForNull;
 import org.checkerframework.checker.nullness.qual.Nullable;
 import org.checkerframework.dataflow.qual.Pure;
 import org.checkerframework.dataflow.qual.SideEffectFree;
@@ -59,8 +60,9 @@
  */
 @AnnotatedFor({"nullness"})
 @GwtCompatible
-@SuppressWarnings("nullness:generic.argument")
-public abstract class ForwardingMap<K, V> extends ForwardingObject implements Map<K, V> {
+@ElementTypesAreNonnullByDefault
+public abstract class ForwardingMap<K extends @Nullable Object, V extends @Nullable Object>
+    extends ForwardingObject implements Map<K, V> {
   // TODO(lowasser): identify places where thread safety is actually lost
 
   /** Constructor for use by subclasses. */
@@ -71,6 +73,7 @@ protected ForwardingMap() {}
 
   @Pure
   @Override
+  @SuppressWarnings("index:overriding.return")
   public int size() {
     return delegate().size();
   }
@@ -83,8 +86,9 @@ public boolean isEmpty() {
 
   @CanIgnoreReturnValue
   @Override
-  @SuppressWarnings("nullness") // Suppressed due to annotations on remove in Java.Map
-  public @Nullable V remove(@Nullable Object key) {
+  @SuppressWarnings("nullness:argument") // Suppressed due to annotations on remove in Java.Map
+  @CheckForNull
+  public V remove(@CheckForNull Object key) {
     return delegate().remove(key);
   }
 
@@ -95,27 +99,29 @@ public void clear() {
 
   @Pure
   @Override
-  @SuppressWarnings("nullness") // Suppressed due to annotations on containsKey in Java.Map
-  public boolean containsKey(@Nullable Object key) {
+  @SuppressWarnings("nullness:argument") // Suppressed due to annotations on containsKey in Java.Map
+  public boolean containsKey(@CheckForNull Object key) {
     return delegate().containsKey(key);
   }
 
   @Pure
   @Override
-  @SuppressWarnings("nullness") // Suppressed due to annotations on containsValue in Java.Map
-  public boolean containsValue(@Nullable Object value) {
+  @SuppressWarnings("nullness:argument") // Suppressed due to annotations on containsValue in Java.Map
+  public boolean containsValue(@CheckForNull Object value) {
     return delegate().containsValue(value);
   }
 
   @Override
-  @SuppressWarnings("nullness") // Suppressed due to annotations on get in Java.Map
-  public V get(@Nullable Object key) {
+  @SuppressWarnings("nullness:argument") // Suppressed due to annotations on get in Java.Map
+  @CheckForNull
+  public V get(@CheckForNull Object key) {
     return delegate().get(key);
   }
 
   @CanIgnoreReturnValue
   @Override
-  public V put(K key, V value) {
+  @CheckForNull
+  public V put(@ParametricNullness K key, @ParametricNullness V value) {
     return delegate().put(key, value);
   }
 
@@ -144,7 +150,7 @@ public Set<Entry<K, V>> entrySet() {
 
   @Pure
   @Override
-  public boolean equals(@Nullable Object object) {
+  public boolean equals(@CheckForNull Object object) {
     return object == this || delegate().equals(object);
   }
 
@@ -176,7 +182,8 @@ protected void standardPutAll(Map<? extends K, ? extends V> map) {
    * @since 7.0
    */
   @Beta
-  protected V standardRemove(@Nullable Object key) {
+  @CheckForNull
+  protected V standardRemove(@CheckForNull Object key) {
     Iterator<Entry<K, V>> entryIterator = entrySet().iterator();
     while (entryIterator.hasNext()) {
       Entry<K, V> entry = entryIterator.next();
@@ -225,7 +232,7 @@ public StandardKeySet() {
    * @since 7.0
    */
   @Beta
-  protected boolean standardContainsKey(@Nullable Object key) {
+  protected boolean standardContainsKey(@CheckForNull Object key) {
     return Maps.containsKeyImpl(this, key);
   }
 
@@ -253,7 +260,7 @@ public StandardValues() {
    *
    * @since 7.0
    */
-  protected boolean standardContainsValue(@Nullable Object value) {
+  protected boolean standardContainsValue(@CheckForNull Object value) {
     return Maps.containsValueImpl(this, value);
   }
 
@@ -295,7 +302,7 @@ protected boolean standardIsEmpty() {
    *
    * @since 7.0
    */
-  protected boolean standardEquals(@Nullable Object object) {
+  protected boolean standardEquals(@CheckForNull Object object) {
     return Maps.equalsImpl(this, object);
   }
 
diff --git a/guava/src/com/google/common/collect/ForwardingMapEntry.java b/guava/src/com/google/common/collect/ForwardingMapEntry.java
index 10d41bdb5c6f..c1f6cf19ef84 100644
--- a/guava/src/com/google/common/collect/ForwardingMapEntry.java
+++ b/guava/src/com/google/common/collect/ForwardingMapEntry.java
@@ -21,6 +21,7 @@
 import com.google.common.base.Objects;
 import java.util.Map;
 import java.util.Map.Entry;
+import javax.annotation.CheckForNull;
 import org.checkerframework.checker.nullness.qual.Nullable;
 import org.checkerframework.dataflow.qual.Pure;
 import org.checkerframework.framework.qual.AnnotatedFor;
@@ -50,8 +51,9 @@
  */
 @AnnotatedFor({"nullness"})
 @GwtCompatible
-@SuppressWarnings("nullness:generic.argument")
-public abstract class ForwardingMapEntry<K, V> extends ForwardingObject implements Map.Entry<K, V> {
+@ElementTypesAreNonnullByDefault
+public abstract class ForwardingMapEntry<K extends @Nullable Object, V extends @Nullable Object>
+    extends ForwardingObject implements Map.Entry<K, V> {
   // TODO(lowasser): identify places where thread safety is actually lost
 
   /** Constructor for use by subclasses. */
@@ -62,24 +64,27 @@ protected ForwardingMapEntry() {}
 
   @Pure
   @Override
+  @ParametricNullness
   public K getKey() {
     return delegate().getKey();
   }
 
   @Pure
   @Override
+  @ParametricNullness
   public V getValue() {
     return delegate().getValue();
   }
 
   @Override
-  public V setValue(V value) {
+  @ParametricNullness
+  public V setValue(@ParametricNullness V value) {
     return delegate().setValue(value);
   }
 
   @Pure
   @Override
-  public boolean equals(@Nullable Object object) {
+  public boolean equals(@CheckForNull Object object) {
     return delegate().equals(object);
   }
 
@@ -96,7 +101,7 @@ public int hashCode() {
    *
    * @since 7.0
    */
-  protected boolean standardEquals(@Nullable Object object) {
+  protected boolean standardEquals(@CheckForNull Object object) {
     if (object instanceof Entry) {
       Entry<?, ?> that = (Entry<?, ?>) object;
       return Objects.equal(this.getKey(), that.getKey())
diff --git a/guava/src/com/google/common/collect/ForwardingMultimap.java b/guava/src/com/google/common/collect/ForwardingMultimap.java
index dc854e778079..cd29727fbe8c 100644
--- a/guava/src/com/google/common/collect/ForwardingMultimap.java
+++ b/guava/src/com/google/common/collect/ForwardingMultimap.java
@@ -22,6 +22,7 @@
 import java.util.Map;
 import java.util.Map.Entry;
 import java.util.Set;
+import javax.annotation.CheckForNull;
 import org.checkerframework.checker.nullness.qual.Nullable;
 import org.checkerframework.dataflow.qual.Pure;
 import org.checkerframework.dataflow.qual.SideEffectFree;
@@ -41,7 +42,9 @@
  */
 @AnnotatedFor({"nullness"})
 @GwtCompatible
-public abstract class ForwardingMultimap<K, V> extends ForwardingObject implements Multimap<K, V> {
+@ElementTypesAreNonnullByDefault
+public abstract class ForwardingMultimap<K extends @Nullable Object, V extends @Nullable Object>
+    extends ForwardingObject implements Multimap<K, V> {
 
   /** Constructor for use by subclasses. */
   protected ForwardingMultimap() {}
@@ -61,19 +64,19 @@ public void clear() {
 
   @Pure
   @Override
-  public boolean containsEntry(@Nullable Object key, @Nullable Object value) {
+  public boolean containsEntry(@CheckForNull Object key, @CheckForNull Object value) {
     return delegate().containsEntry(key, value);
   }
 
   @Pure
   @Override
-  public boolean containsKey(@Nullable Object key) {
+  public boolean containsKey(@CheckForNull Object key) {
     return delegate().containsKey(key);
   }
 
   @Pure
   @Override
-  public boolean containsValue(@Nullable Object value) {
+  public boolean containsValue(@CheckForNull Object value) {
     return delegate().containsValue(value);
   }
 
@@ -84,7 +87,7 @@ public Collection<Entry<K, V>> entries() {
   }
 
   @Override
-  public Collection<V> get(@Nullable K key) {
+  public Collection<V> get(@ParametricNullness K key) {
     return delegate().get(key);
   }
 
@@ -107,13 +110,13 @@ public Set<K> keySet() {
 
   @CanIgnoreReturnValue
   @Override
-  public boolean put(K key, V value) {
+  public boolean put(@ParametricNullness K key, @ParametricNullness V value) {
     return delegate().put(key, value);
   }
 
   @CanIgnoreReturnValue
   @Override
-  public boolean putAll(K key, Iterable<? extends V> values) {
+  public boolean putAll(@ParametricNullness K key, Iterable<? extends V> values) {
     return delegate().putAll(key, values);
   }
 
@@ -125,19 +128,19 @@ public boolean putAll(Multimap<? extends K, ? extends V> multimap) {
 
   @CanIgnoreReturnValue
   @Override
-  public boolean remove(@Nullable Object key, @Nullable Object value) {
+  public boolean remove(@CheckForNull Object key, @CheckForNull Object value) {
     return delegate().remove(key, value);
   }
 
   @CanIgnoreReturnValue
   @Override
-  public Collection<V> removeAll(@Nullable Object key) {
+  public Collection<V> removeAll(@CheckForNull Object key) {
     return delegate().removeAll(key);
   }
 
   @CanIgnoreReturnValue
   @Override
-  public Collection<V> replaceValues(K key, Iterable<? extends V> values) {
+  public Collection<V> replaceValues(@ParametricNullness K key, Iterable<? extends V> values) {
     return delegate().replaceValues(key, values);
   }
 
@@ -155,7 +158,7 @@ public Collection<V> values() {
 
   @Pure
   @Override
-  public boolean equals(@Nullable Object object) {
+  public boolean equals(@CheckForNull Object object) {
     return object == this || delegate().equals(object);
   }
 
diff --git a/guava/src/com/google/common/collect/ForwardingMultiset.java b/guava/src/com/google/common/collect/ForwardingMultiset.java
index aafa3186a8dc..72bc3cf6406f 100644
--- a/guava/src/com/google/common/collect/ForwardingMultiset.java
+++ b/guava/src/com/google/common/collect/ForwardingMultiset.java
@@ -23,6 +23,7 @@
 import java.util.Collection;
 import java.util.Iterator;
 import java.util.Set;
+import javax.annotation.CheckForNull;
 import org.checkerframework.checker.nullness.qual.Nullable;
 import org.checkerframework.dataflow.qual.Pure;
 import org.checkerframework.dataflow.qual.SideEffectFree;
@@ -52,7 +53,9 @@
  */
 @AnnotatedFor({"nullness"})
 @GwtCompatible
-public abstract class ForwardingMultiset<E> extends ForwardingCollection<E> implements Multiset<E> {
+@ElementTypesAreNonnullByDefault
+public abstract class ForwardingMultiset<E extends @Nullable Object> extends ForwardingCollection<E>
+    implements Multiset<E> {
 
   /** Constructor for use by subclasses. */
   protected ForwardingMultiset() {}
@@ -61,19 +64,19 @@ protected ForwardingMultiset() {}
   protected abstract Multiset<E> delegate();
 
   @Override
-  public int count(@Nullable Object element) {
+  public int count(@CheckForNull Object element) {
     return delegate().count(element);
   }
 
   @CanIgnoreReturnValue
   @Override
-  public int add(E element, int occurrences) {
+  public int add(@ParametricNullness E element, int occurrences) {
     return delegate().add(element, occurrences);
   }
 
   @CanIgnoreReturnValue
   @Override
-  public int remove(@Nullable Object element, int occurrences) {
+  public int remove(@CheckForNull Object element, int occurrences) {
     return delegate().remove(element, occurrences);
   }
 
@@ -91,7 +94,7 @@ public Set<Entry<E>> entrySet() {
 
   @Pure
   @Override
-  public boolean equals(@Nullable Object object) {
+  public boolean equals(@CheckForNull Object object) {
     return object == this || delegate().equals(object);
   }
 
@@ -103,13 +106,13 @@ public int hashCode() {
 
   @CanIgnoreReturnValue
   @Override
-  public int setCount(E element, int count) {
+  public int setCount(@ParametricNullness E element, int count) {
     return delegate().setCount(element, count);
   }
 
   @CanIgnoreReturnValue
   @Override
-  public boolean setCount(E element, int oldCount, int newCount) {
+  public boolean setCount(@ParametricNullness E element, int oldCount, int newCount) {
     return delegate().setCount(element, oldCount, newCount);
   }
 
@@ -120,7 +123,7 @@ public boolean setCount(E element, int oldCount, int newCount) {
    * @since 7.0
    */
   @Override
-  protected boolean standardContains(@Nullable Object object) {
+  protected boolean standardContains(@CheckForNull Object object) {
     return count(object) > 0;
   }
 
@@ -144,7 +147,7 @@ protected void standardClear() {
    * @since 7.0
    */
   @Beta
-  protected int standardCount(@Nullable Object object) {
+  protected int standardCount(@CheckForNull Object object) {
     for (Entry<?> entry : this.entrySet()) {
       if (Objects.equal(entry.getElement(), object)) {
         return entry.getCount();
@@ -160,7 +163,7 @@ protected int standardCount(@Nullable Object object) {
    *
    * @since 7.0
    */
-  protected boolean standardAdd(E element) {
+  protected boolean standardAdd(@ParametricNullness E element) {
     add(element, 1);
     return true;
   }
@@ -186,7 +189,7 @@ protected boolean standardAddAll(Collection<? extends E> elementsToAdd) {
    * @since 7.0
    */
   @Override
-  protected boolean standardRemove(Object element) {
+  protected boolean standardRemove(@CheckForNull Object element) {
     return remove(element, 1) > 0;
   }
 
@@ -222,7 +225,7 @@ protected boolean standardRetainAll(Collection<?> elementsToRetain) {
    *
    * @since 7.0
    */
-  protected int standardSetCount(E element, int count) {
+  protected int standardSetCount(@ParametricNullness E element, int count) {
     return Multisets.setCountImpl(this, element, count);
   }
 
@@ -233,7 +236,7 @@ protected int standardSetCount(E element, int count) {
    *
    * @since 7.0
    */
-  protected boolean standardSetCount(E element, int oldCount, int newCount) {
+  protected boolean standardSetCount(@ParametricNullness E element, int oldCount, int newCount) {
     return Multisets.setCountImpl(this, element, oldCount, newCount);
   }
 
@@ -293,7 +296,7 @@ protected int standardSize() {
    *
    * @since 7.0
    */
-  protected boolean standardEquals(@Nullable Object object) {
+  protected boolean standardEquals(@CheckForNull Object object) {
     return Multisets.equalsImpl(this, object);
   }
 
diff --git a/guava/src/com/google/common/collect/ForwardingNavigableMap.java b/guava/src/com/google/common/collect/ForwardingNavigableMap.java
index 5f23d05c8b39..c32468da1d21 100644
--- a/guava/src/com/google/common/collect/ForwardingNavigableMap.java
+++ b/guava/src/com/google/common/collect/ForwardingNavigableMap.java
@@ -16,7 +16,6 @@
 
 package com.google.common.collect;
 
-import static com.google.common.collect.CollectPreconditions.checkRemove;
 import static com.google.common.collect.Maps.keyOrNull;
 
 import com.google.common.annotations.Beta;
@@ -27,6 +26,8 @@
 import java.util.NoSuchElementException;
 import java.util.SortedMap;
 import java.util.function.BiFunction;
+import javax.annotation.CheckForNull;
+import org.checkerframework.checker.nullness.qual.Nullable;
 
 /**
  * A navigable map which forwards all its method calls to another navigable map. Subclasses should
@@ -55,8 +56,9 @@
  * @since 12.0
  */
 @GwtIncompatible
-public abstract class ForwardingNavigableMap<K, V> extends ForwardingSortedMap<K, V>
-    implements NavigableMap<K, V> {
+@ElementTypesAreNonnullByDefault
+public abstract class ForwardingNavigableMap<K extends @Nullable Object, V extends @Nullable Object>
+    extends ForwardingSortedMap<K, V> implements NavigableMap<K, V> {
 
   /** Constructor for use by subclasses. */
   protected ForwardingNavigableMap() {}
@@ -65,7 +67,8 @@ protected ForwardingNavigableMap() {}
   protected abstract NavigableMap<K, V> delegate();
 
   @Override
-  public Entry<K, V> lowerEntry(K key) {
+  @CheckForNull
+  public Entry<K, V> lowerEntry(@ParametricNullness K key) {
     return delegate().lowerEntry(key);
   }
 
@@ -74,12 +77,14 @@ public Entry<K, V> lowerEntry(K key) {
    * #headMap(Object, boolean)}. If you override {@code headMap}, you may wish to override {@code
    * lowerEntry} to forward to this implementation.
    */
-  protected Entry<K, V> standardLowerEntry(K key) {
+  @CheckForNull
+  protected Entry<K, V> standardLowerEntry(@ParametricNullness K key) {
     return headMap(key, false).lastEntry();
   }
 
   @Override
-  public K lowerKey(K key) {
+  @CheckForNull
+  public K lowerKey(@ParametricNullness K key) {
     return delegate().lowerKey(key);
   }
 
@@ -88,12 +93,14 @@ public K lowerKey(K key) {
    * {@link #lowerEntry}, you may wish to override {@code lowerKey} to forward to this
    * implementation.
    */
-  protected K standardLowerKey(K key) {
+  @CheckForNull
+  protected K standardLowerKey(@ParametricNullness K key) {
     return keyOrNull(lowerEntry(key));
   }
 
   @Override
-  public Entry<K, V> floorEntry(K key) {
+  @CheckForNull
+  public Entry<K, V> floorEntry(@ParametricNullness K key) {
     return delegate().floorEntry(key);
   }
 
@@ -102,12 +109,14 @@ public Entry<K, V> floorEntry(K key) {
    * #headMap(Object, boolean)}. If you override {@code headMap}, you may wish to override {@code
    * floorEntry} to forward to this implementation.
    */
-  protected Entry<K, V> standardFloorEntry(K key) {
+  @CheckForNull
+  protected Entry<K, V> standardFloorEntry(@ParametricNullness K key) {
     return headMap(key, true).lastEntry();
   }
 
   @Override
-  public K floorKey(K key) {
+  @CheckForNull
+  public K floorKey(@ParametricNullness K key) {
     return delegate().floorKey(key);
   }
 
@@ -116,12 +125,14 @@ public K floorKey(K key) {
    * {@code floorEntry}, you may wish to override {@code floorKey} to forward to this
    * implementation.
    */
-  protected K standardFloorKey(K key) {
+  @CheckForNull
+  protected K standardFloorKey(@ParametricNullness K key) {
     return keyOrNull(floorEntry(key));
   }
 
   @Override
-  public Entry<K, V> ceilingEntry(K key) {
+  @CheckForNull
+  public Entry<K, V> ceilingEntry(@ParametricNullness K key) {
     return delegate().ceilingEntry(key);
   }
 
@@ -130,12 +141,14 @@ public Entry<K, V> ceilingEntry(K key) {
    * #tailMap(Object, boolean)}. If you override {@code tailMap}, you may wish to override {@code
    * ceilingEntry} to forward to this implementation.
    */
-  protected Entry<K, V> standardCeilingEntry(K key) {
+  @CheckForNull
+  protected Entry<K, V> standardCeilingEntry(@ParametricNullness K key) {
     return tailMap(key, true).firstEntry();
   }
 
   @Override
-  public K ceilingKey(K key) {
+  @CheckForNull
+  public K ceilingKey(@ParametricNullness K key) {
     return delegate().ceilingKey(key);
   }
 
@@ -144,12 +157,14 @@ public K ceilingKey(K key) {
    * {@code ceilingEntry}, you may wish to override {@code ceilingKey} to forward to this
    * implementation.
    */
-  protected K standardCeilingKey(K key) {
+  @CheckForNull
+  protected K standardCeilingKey(@ParametricNullness K key) {
     return keyOrNull(ceilingEntry(key));
   }
 
   @Override
-  public Entry<K, V> higherEntry(K key) {
+  @CheckForNull
+  public Entry<K, V> higherEntry(@ParametricNullness K key) {
     return delegate().higherEntry(key);
   }
 
@@ -158,12 +173,14 @@ public Entry<K, V> higherEntry(K key) {
    * #tailMap(Object, boolean)}. If you override {@code tailMap}, you may wish to override {@code
    * higherEntry} to forward to this implementation.
    */
-  protected Entry<K, V> standardHigherEntry(K key) {
+  @CheckForNull
+  protected Entry<K, V> standardHigherEntry(@ParametricNullness K key) {
     return tailMap(key, false).firstEntry();
   }
 
   @Override
-  public K higherKey(K key) {
+  @CheckForNull
+  public K higherKey(@ParametricNullness K key) {
     return delegate().higherKey(key);
   }
 
@@ -172,11 +189,13 @@ public K higherKey(K key) {
    * {@code higherEntry}, you may wish to override {@code higherKey} to forward to this
    * implementation.
    */
-  protected K standardHigherKey(K key) {
+  @CheckForNull
+  protected K standardHigherKey(@ParametricNullness K key) {
     return keyOrNull(higherEntry(key));
   }
 
   @Override
+  @CheckForNull
   public Entry<K, V> firstEntry() {
     return delegate().firstEntry();
   }
@@ -186,6 +205,7 @@ public Entry<K, V> firstEntry() {
    * #entrySet}. If you override {@code entrySet}, you may wish to override {@code firstEntry} to
    * forward to this implementation.
    */
+  @CheckForNull
   protected Entry<K, V> standardFirstEntry() {
     return Iterables.getFirst(entrySet(), null);
   }
@@ -205,6 +225,7 @@ protected K standardFirstKey() {
   }
 
   @Override
+  @CheckForNull
   public Entry<K, V> lastEntry() {
     return delegate().lastEntry();
   }
@@ -214,6 +235,7 @@ public Entry<K, V> lastEntry() {
    * #entrySet} of {@link #descendingMap}. If you override {@code descendingMap}, you may wish to
    * override {@code lastEntry} to forward to this implementation.
    */
+  @CheckForNull
   protected Entry<K, V> standardLastEntry() {
     return Iterables.getFirst(descendingMap().entrySet(), null);
   }
@@ -232,6 +254,7 @@ protected K standardLastKey() {
   }
 
   @Override
+  @CheckForNull
   public Entry<K, V> pollFirstEntry() {
     return delegate().pollFirstEntry();
   }
@@ -241,11 +264,13 @@ public Entry<K, V> pollFirstEntry() {
    * entrySet}. If you override {@code entrySet}, you may wish to override {@code pollFirstEntry} to
    * forward to this implementation.
    */
+  @CheckForNull
   protected Entry<K, V> standardPollFirstEntry() {
     return Iterators.pollNext(entrySet().iterator());
   }
 
   @Override
+  @CheckForNull
   public Entry<K, V> pollLastEntry() {
     return delegate().pollLastEntry();
   }
@@ -255,6 +280,7 @@ public Entry<K, V> pollLastEntry() {
    * entrySet} of {@code descendingMap}. If you override {@code descendingMap}, you may wish to
    * override {@code pollFirstEntry} to forward to this implementation.
    */
+  @CheckForNull
   protected Entry<K, V> standardPollLastEntry() {
     return Iterators.pollNext(descendingMap().entrySet().iterator());
   }
@@ -293,8 +319,8 @@ public void replaceAll(BiFunction<? super K, ? super V, ? extends V> function) {
     @Override
     protected Iterator<Entry<K, V>> entryIterator() {
       return new Iterator<Entry<K, V>>() {
-        private Entry<K, V> toRemove = null;
-        private Entry<K, V> nextOrNull = forward().lastEntry();
+        @CheckForNull private Entry<K, V> toRemove = null;
+        @CheckForNull private Entry<K, V> nextOrNull = forward().lastEntry();
 
         @Override
         public boolean hasNext() {
@@ -303,7 +329,7 @@ public boolean hasNext() {
 
         @Override
         public java.util.Map.Entry<K, V> next() {
-          if (!hasNext()) {
+          if (nextOrNull == null) {
             throw new NoSuchElementException();
           }
           try {
@@ -316,7 +342,9 @@ public java.util.Map.Entry<K, V> next() {
 
         @Override
         public void remove() {
-          checkRemove(toRemove != null);
+          if (toRemove == null) {
+            throw new IllegalStateException("no calls to next() since the last call to remove()");
+          }
           forward().remove(toRemove.getKey());
           toRemove = null;
         }
@@ -368,22 +396,27 @@ protected NavigableSet<K> standardDescendingKeySet() {
    * wish to override {@code subMap} to forward to this implementation.
    */
   @Override
-  protected SortedMap<K, V> standardSubMap(K fromKey, K toKey) {
+  protected SortedMap<K, V> standardSubMap(
+      @ParametricNullness K fromKey, @ParametricNullness K toKey) {
     return subMap(fromKey, true, toKey, false);
   }
 
   @Override
-  public NavigableMap<K, V> subMap(K fromKey, boolean fromInclusive, K toKey, boolean toInclusive) {
+  public NavigableMap<K, V> subMap(
+      @ParametricNullness K fromKey,
+      boolean fromInclusive,
+      @ParametricNullness K toKey,
+      boolean toInclusive) {
     return delegate().subMap(fromKey, fromInclusive, toKey, toInclusive);
   }
 
   @Override
-  public NavigableMap<K, V> headMap(K toKey, boolean inclusive) {
+  public NavigableMap<K, V> headMap(@ParametricNullness K toKey, boolean inclusive) {
     return delegate().headMap(toKey, inclusive);
   }
 
   @Override
-  public NavigableMap<K, V> tailMap(K fromKey, boolean inclusive) {
+  public NavigableMap<K, V> tailMap(@ParametricNullness K fromKey, boolean inclusive) {
     return delegate().tailMap(fromKey, inclusive);
   }
 
@@ -392,7 +425,7 @@ public NavigableMap<K, V> tailMap(K fromKey, boolean inclusive) {
    * boolean)}. If you override {@code headMap(K, boolean)}, you may wish to override {@code
    * headMap} to forward to this implementation.
    */
-  protected SortedMap<K, V> standardHeadMap(K toKey) {
+  protected SortedMap<K, V> standardHeadMap(@ParametricNullness K toKey) {
     return headMap(toKey, false);
   }
 
@@ -401,7 +434,7 @@ protected SortedMap<K, V> standardHeadMap(K toKey) {
    * boolean)}. If you override {@code tailMap(K, boolean)}, you may wish to override {@code
    * tailMap} to forward to this implementation.
    */
-  protected SortedMap<K, V> standardTailMap(K fromKey) {
+  protected SortedMap<K, V> standardTailMap(@ParametricNullness K fromKey) {
     return tailMap(fromKey, true);
   }
 }
diff --git a/guava/src/com/google/common/collect/ForwardingNavigableSet.java b/guava/src/com/google/common/collect/ForwardingNavigableSet.java
index 827698edd545..6822aa87d4fc 100644
--- a/guava/src/com/google/common/collect/ForwardingNavigableSet.java
+++ b/guava/src/com/google/common/collect/ForwardingNavigableSet.java
@@ -21,6 +21,8 @@
 import java.util.Iterator;
 import java.util.NavigableSet;
 import java.util.SortedSet;
+import javax.annotation.CheckForNull;
+import org.checkerframework.checker.nullness.qual.Nullable;
 
 /**
  * A navigable set which forwards all its method calls to another navigable set. Subclasses should
@@ -49,8 +51,9 @@
  * @since 12.0
  */
 @GwtIncompatible
-public abstract class ForwardingNavigableSet<E> extends ForwardingSortedSet<E>
-    implements NavigableSet<E> {
+@ElementTypesAreNonnullByDefault
+public abstract class ForwardingNavigableSet<E extends @Nullable Object>
+    extends ForwardingSortedSet<E> implements NavigableSet<E> {
 
   /** Constructor for use by subclasses. */
   protected ForwardingNavigableSet() {}
@@ -59,7 +62,8 @@ protected ForwardingNavigableSet() {}
   protected abstract NavigableSet<E> delegate();
 
   @Override
-  public E lower(E e) {
+  @CheckForNull
+  public E lower(@ParametricNullness E e) {
     return delegate().lower(e);
   }
 
@@ -68,12 +72,14 @@ public E lower(E e) {
    * {@link #headSet(Object, boolean)}. If you override {@link #headSet(Object, boolean)}, you may
    * wish to override {@link #lower} to forward to this implementation.
    */
-  protected E standardLower(E e) {
+  @CheckForNull
+  protected E standardLower(@ParametricNullness E e) {
     return Iterators.getNext(headSet(e, false).descendingIterator(), null);
   }
 
   @Override
-  public E floor(E e) {
+  @CheckForNull
+  public E floor(@ParametricNullness E e) {
     return delegate().floor(e);
   }
 
@@ -82,12 +88,14 @@ public E floor(E e) {
    * {@link #headSet(Object, boolean)}. If you override {@link #headSet(Object, boolean)}, you may
    * wish to override {@link #floor} to forward to this implementation.
    */
-  protected E standardFloor(E e) {
+  @CheckForNull
+  protected E standardFloor(@ParametricNullness E e) {
     return Iterators.getNext(headSet(e, true).descendingIterator(), null);
   }
 
   @Override
-  public E ceiling(E e) {
+  @CheckForNull
+  public E ceiling(@ParametricNullness E e) {
     return delegate().ceiling(e);
   }
 
@@ -96,12 +104,14 @@ public E ceiling(E e) {
    * #tailSet(Object, boolean)}. If you override {@link #tailSet(Object, boolean)}, you may wish to
    * override {@link #ceiling} to forward to this implementation.
    */
-  protected E standardCeiling(E e) {
+  @CheckForNull
+  protected E standardCeiling(@ParametricNullness E e) {
     return Iterators.getNext(tailSet(e, true).iterator(), null);
   }
 
   @Override
-  public E higher(E e) {
+  @CheckForNull
+  public E higher(@ParametricNullness E e) {
     return delegate().higher(e);
   }
 
@@ -110,11 +120,13 @@ public E higher(E e) {
    * #tailSet(Object, boolean)}. If you override {@link #tailSet(Object, boolean)}, you may wish to
    * override {@link #higher} to forward to this implementation.
    */
-  protected E standardHigher(E e) {
+  @CheckForNull
+  protected E standardHigher(@ParametricNullness E e) {
     return Iterators.getNext(tailSet(e, false).iterator(), null);
   }
 
   @Override
+  @CheckForNull
   public E pollFirst() {
     return delegate().pollFirst();
   }
@@ -124,11 +136,13 @@ public E pollFirst() {
    * override {@link #iterator} you may wish to override {@link #pollFirst} to forward to this
    * implementation.
    */
+  @CheckForNull
   protected E standardPollFirst() {
     return Iterators.pollNext(iterator());
   }
 
   @Override
+  @CheckForNull
   public E pollLast() {
     return delegate().pollLast();
   }
@@ -138,14 +152,17 @@ public E pollLast() {
    * If you override {@link #descendingIterator} you may wish to override {@link #pollLast} to
    * forward to this implementation.
    */
+  @CheckForNull
   protected E standardPollLast() {
     return Iterators.pollNext(descendingIterator());
   }
 
+  @ParametricNullness
   protected E standardFirst() {
     return iterator().next();
   }
 
+  @ParametricNullness
   protected E standardLast() {
     return descendingIterator().next();
   }
@@ -179,7 +196,10 @@ public Iterator<E> descendingIterator() {
 
   @Override
   public NavigableSet<E> subSet(
-      E fromElement, boolean fromInclusive, E toElement, boolean toInclusive) {
+      @ParametricNullness E fromElement,
+      boolean fromInclusive,
+      @ParametricNullness E toElement,
+      boolean toInclusive) {
     return delegate().subSet(fromElement, fromInclusive, toElement, toInclusive);
   }
 
@@ -190,7 +210,10 @@ public NavigableSet<E> subSet(
    */
   @Beta
   protected NavigableSet<E> standardSubSet(
-      E fromElement, boolean fromInclusive, E toElement, boolean toInclusive) {
+      @ParametricNullness E fromElement,
+      boolean fromInclusive,
+      @ParametricNullness E toElement,
+      boolean toInclusive) {
     return tailSet(fromElement, fromInclusive).headSet(toElement, toInclusive);
   }
 
@@ -201,12 +224,13 @@ protected NavigableSet<E> standardSubSet(
    * implementation.
    */
   @Override
-  protected SortedSet<E> standardSubSet(E fromElement, E toElement) {
+  protected SortedSet<E> standardSubSet(
+      @ParametricNullness E fromElement, @ParametricNullness E toElement) {
     return subSet(fromElement, true, toElement, false);
   }
 
   @Override
-  public NavigableSet<E> headSet(E toElement, boolean inclusive) {
+  public NavigableSet<E> headSet(@ParametricNullness E toElement, boolean inclusive) {
     return delegate().headSet(toElement, inclusive);
   }
 
@@ -215,12 +239,12 @@ public NavigableSet<E> headSet(E toElement, boolean inclusive) {
    * boolean)} method. If you override {@link #headSet(Object, boolean)}, you may wish to override
    * {@link #headSet(Object)} to forward to this implementation.
    */
-  protected SortedSet<E> standardHeadSet(E toElement) {
+  protected SortedSet<E> standardHeadSet(@ParametricNullness E toElement) {
     return headSet(toElement, false);
   }
 
   @Override
-  public NavigableSet<E> tailSet(E fromElement, boolean inclusive) {
+  public NavigableSet<E> tailSet(@ParametricNullness E fromElement, boolean inclusive) {
     return delegate().tailSet(fromElement, inclusive);
   }
 
@@ -229,7 +253,7 @@ public NavigableSet<E> tailSet(E fromElement, boolean inclusive) {
    * boolean)} method. If you override {@link #tailSet(Object, boolean)}, you may wish to override
    * {@link #tailSet(Object)} to forward to this implementation.
    */
-  protected SortedSet<E> standardTailSet(E fromElement) {
+  protected SortedSet<E> standardTailSet(@ParametricNullness E fromElement) {
     return tailSet(fromElement, true);
   }
 }
diff --git a/guava/src/com/google/common/collect/ForwardingObject.java b/guava/src/com/google/common/collect/ForwardingObject.java
index dc1ff23e5e1f..6a55a8541134 100644
--- a/guava/src/com/google/common/collect/ForwardingObject.java
+++ b/guava/src/com/google/common/collect/ForwardingObject.java
@@ -47,6 +47,7 @@
  */
 @AnnotatedFor({"nullness"})
 @GwtCompatible
+@ElementTypesAreNonnullByDefault
 public abstract class ForwardingObject {
 
   /** Constructor for use by subclasses. */
diff --git a/guava/src/com/google/common/collect/ForwardingQueue.java b/guava/src/com/google/common/collect/ForwardingQueue.java
index 710f81968522..d76581f5f336 100644
--- a/guava/src/com/google/common/collect/ForwardingQueue.java
+++ b/guava/src/com/google/common/collect/ForwardingQueue.java
@@ -20,6 +20,8 @@
 import com.google.errorprone.annotations.CanIgnoreReturnValue;
 import java.util.NoSuchElementException;
 import java.util.Queue;
+import javax.annotation.CheckForNull;
+import org.checkerframework.checker.nullness.qual.Nullable;
 import org.checkerframework.framework.qual.AnnotatedFor;
 
 /**
@@ -46,7 +48,9 @@
  */
 @AnnotatedFor({"nullness"})
 @GwtCompatible
-public abstract class ForwardingQueue<E> extends ForwardingCollection<E> implements Queue<E> {
+@ElementTypesAreNonnullByDefault
+public abstract class ForwardingQueue<E extends @Nullable Object> extends ForwardingCollection<E>
+    implements Queue<E> {
 
   /** Constructor for use by subclasses. */
   protected ForwardingQueue() {}
@@ -56,28 +60,32 @@ protected ForwardingQueue() {}
 
   @CanIgnoreReturnValue // TODO(cpovirk): Consider removing this?
   @Override
-  public boolean offer(E o) {
+  public boolean offer(@ParametricNullness E o) {
     return delegate().offer(o);
   }
 
   @CanIgnoreReturnValue // TODO(cpovirk): Consider removing this?
   @Override
+  @CheckForNull
   public E poll() {
     return delegate().poll();
   }
 
   @CanIgnoreReturnValue
   @Override
+  @ParametricNullness
   public E remove() {
     return delegate().remove();
   }
 
   @Override
+  @CheckForNull
   public E peek() {
     return delegate().peek();
   }
 
   @Override
+  @ParametricNullness
   public E element() {
     return delegate().element();
   }
@@ -88,7 +96,7 @@ public E element() {
    *
    * @since 7.0
    */
-  protected boolean standardOffer(E e) {
+  protected boolean standardOffer(@ParametricNullness E e) {
     try {
       return add(e);
     } catch (IllegalStateException caught) {
@@ -102,6 +110,7 @@ protected boolean standardOffer(E e) {
    *
    * @since 7.0
    */
+  @CheckForNull
   protected E standardPeek() {
     try {
       return element();
@@ -116,6 +125,7 @@ protected E standardPeek() {
    *
    * @since 7.0
    */
+  @CheckForNull
   protected E standardPoll() {
     try {
       return remove();
diff --git a/guava/src/com/google/common/collect/ForwardingSet.java b/guava/src/com/google/common/collect/ForwardingSet.java
index ab6795a973a8..fd9496276929 100644
--- a/guava/src/com/google/common/collect/ForwardingSet.java
+++ b/guava/src/com/google/common/collect/ForwardingSet.java
@@ -21,6 +21,7 @@
 import com.google.common.annotations.GwtCompatible;
 import java.util.Collection;
 import java.util.Set;
+import javax.annotation.CheckForNull;
 import org.checkerframework.checker.nullness.qual.Nullable;
 import org.checkerframework.dataflow.qual.Pure;
 import org.checkerframework.framework.qual.AnnotatedFor;
@@ -49,7 +50,9 @@
  */
 @AnnotatedFor({"nullness"})
 @GwtCompatible
-public abstract class ForwardingSet<E> extends ForwardingCollection<E> implements Set<E> {
+@ElementTypesAreNonnullByDefault
+public abstract class ForwardingSet<E extends @Nullable Object> extends ForwardingCollection<E>
+    implements Set<E> {
   // TODO(lowasser): identify places where thread safety is actually lost
 
   /** Constructor for use by subclasses. */
@@ -60,7 +63,7 @@ protected ForwardingSet() {}
 
   @Pure
   @Override
-  public boolean equals(@Nullable Object object) {
+  public boolean equals(@CheckForNull Object object) {
     return object == this || delegate().equals(object);
   }
 
@@ -89,7 +92,7 @@ protected boolean standardRemoveAll(Collection<?> collection) {
    *
    * @since 7.0
    */
-  protected boolean standardEquals(@Nullable Object object) {
+  protected boolean standardEquals(@CheckForNull Object object) {
     return Sets.equalsImpl(this, object);
   }
 
diff --git a/guava/src/com/google/common/collect/ForwardingSetMultimap.java b/guava/src/com/google/common/collect/ForwardingSetMultimap.java
index a4d6c76f5d5b..5077c6803cf9 100644
--- a/guava/src/com/google/common/collect/ForwardingSetMultimap.java
+++ b/guava/src/com/google/common/collect/ForwardingSetMultimap.java
@@ -20,6 +20,7 @@
 import com.google.errorprone.annotations.CanIgnoreReturnValue;
 import java.util.Map.Entry;
 import java.util.Set;
+import javax.annotation.CheckForNull;
 import org.checkerframework.checker.nullness.qual.Nullable;
 
 /**
@@ -35,8 +36,9 @@
  * @since 3.0
  */
 @GwtCompatible
-public abstract class ForwardingSetMultimap<K, V> extends ForwardingMultimap<K, V>
-    implements SetMultimap<K, V> {
+@ElementTypesAreNonnullByDefault
+public abstract class ForwardingSetMultimap<K extends @Nullable Object, V extends @Nullable Object>
+    extends ForwardingMultimap<K, V> implements SetMultimap<K, V> {
 
   @Override
   protected abstract SetMultimap<K, V> delegate();
@@ -47,19 +49,19 @@ public Set<Entry<K, V>> entries() {
   }
 
   @Override
-  public Set<V> get(@Nullable K key) {
+  public Set<V> get(@ParametricNullness K key) {
     return delegate().get(key);
   }
 
   @CanIgnoreReturnValue
   @Override
-  public Set<V> removeAll(@Nullable Object key) {
+  public Set<V> removeAll(@CheckForNull Object key) {
     return delegate().removeAll(key);
   }
 
   @CanIgnoreReturnValue
   @Override
-  public Set<V> replaceValues(K key, Iterable<? extends V> values) {
+  public Set<V> replaceValues(@ParametricNullness K key, Iterable<? extends V> values) {
     return delegate().replaceValues(key, values);
   }
 }
diff --git a/guava/src/com/google/common/collect/ForwardingSortedMap.java b/guava/src/com/google/common/collect/ForwardingSortedMap.java
index 26b4f473f6ba..6fe8bb2563bf 100644
--- a/guava/src/com/google/common/collect/ForwardingSortedMap.java
+++ b/guava/src/com/google/common/collect/ForwardingSortedMap.java
@@ -23,6 +23,7 @@
 import java.util.Comparator;
 import java.util.NoSuchElementException;
 import java.util.SortedMap;
+import javax.annotation.CheckForNull;
 import org.checkerframework.checker.nullness.qual.Nullable;
 import org.checkerframework.dataflow.qual.SideEffectFree;
 import org.checkerframework.framework.qual.AnnotatedFor;
@@ -54,9 +55,9 @@
  */
 @AnnotatedFor({"nullness"})
 @GwtCompatible
-@SuppressWarnings("nullness:generic.argument")
-public abstract class ForwardingSortedMap<K, V> extends ForwardingMap<K, V>
-    implements SortedMap<K, V> {
+@ElementTypesAreNonnullByDefault
+public abstract class ForwardingSortedMap<K extends @Nullable Object, V extends @Nullable Object>
+    extends ForwardingMap<K, V> implements SortedMap<K, V> {
   // TODO(lowasser): identify places where thread safety is actually lost
 
   /** Constructor for use by subclasses. */
@@ -67,32 +68,35 @@ protected ForwardingSortedMap() {}
 
   @SideEffectFree
   @Override
+  @CheckForNull
   public Comparator<? super K> comparator() {
     return delegate().comparator();
   }
 
   @Override
+  @ParametricNullness
   public K firstKey() {
     return delegate().firstKey();
   }
 
   @Override
-  public SortedMap<K, V> headMap(K toKey) {
+  public SortedMap<K, V> headMap(@ParametricNullness K toKey) {
     return delegate().headMap(toKey);
   }
 
   @Override
+  @ParametricNullness
   public K lastKey() {
     return delegate().lastKey();
   }
 
   @Override
-  public SortedMap<K, V> subMap(K fromKey, K toKey) {
+  public SortedMap<K, V> subMap(@ParametricNullness K fromKey, @ParametricNullness K toKey) {
     return delegate().subMap(fromKey, toKey);
   }
 
   @Override
-  public SortedMap<K, V> tailMap(K fromKey) {
+  public SortedMap<K, V> tailMap(@ParametricNullness K fromKey) {
     return delegate().tailMap(fromKey);
   }
 
@@ -111,14 +115,14 @@ public StandardKeySet() {
     }
   }
 
-  // unsafe, but worst case is a CCE is thrown, which callers will be expecting
-  @SuppressWarnings("unchecked")
-  private int unsafeCompare(Object k1, Object k2) {
-    Comparator<? super K> comparator = comparator();
+  // unsafe, but worst case is a CCE or NPE is thrown, which callers will be expecting
+  @SuppressWarnings({"unchecked", "nullness"})
+  static int unsafeCompare(
+      @CheckForNull Comparator<?> comparator, @CheckForNull Object o1, @CheckForNull Object o2) {
     if (comparator == null) {
-      return ((Comparable<Object>) k1).compareTo(k2);
+      return ((Comparable<@Nullable Object>) o1).compareTo(o2);
     } else {
-      return ((Comparator<Object>) comparator).compare(k1, k2);
+      return ((Comparator<@Nullable Object>) comparator).compare(o1, o2);
     }
   }
 
@@ -131,13 +135,13 @@ private int unsafeCompare(Object k1, Object k2) {
    */
   @Override
   @Beta
-  protected boolean standardContainsKey(@Nullable Object key) {
+  protected boolean standardContainsKey(@CheckForNull Object key) {
     try {
-      // any CCE will be caught
-      @SuppressWarnings("unchecked")
-      SortedMap<Object, V> self = (SortedMap<Object, V>) this;
+      // any CCE or NPE will be caught
+      @SuppressWarnings({"unchecked", "nullness"})
+      SortedMap<@Nullable Object, V> self = (SortedMap<@Nullable Object, V>) this;
       Object ceilingKey = self.tailMap(key).firstKey();
-      return unsafeCompare(ceilingKey, key) == 0;
+      return unsafeCompare(comparator(), ceilingKey, key) == 0;
     } catch (ClassCastException | NoSuchElementException | NullPointerException e) {
       return false;
     }
@@ -152,7 +156,7 @@ protected boolean standardContainsKey(@Nullable Object key) {
    */
   @Beta
   protected SortedMap<K, V> standardSubMap(K fromKey, K toKey) {
-    checkArgument(unsafeCompare(fromKey, toKey) <= 0, "fromKey must be <= toKey");
+    checkArgument(unsafeCompare(comparator(), fromKey, toKey) <= 0, "fromKey must be <= toKey");
     return tailMap(fromKey).headMap(toKey);
   }
 }
diff --git a/guava/src/com/google/common/collect/ForwardingSortedMultiset.java b/guava/src/com/google/common/collect/ForwardingSortedMultiset.java
index 1d34fb3d559f..4626d3193a58 100644
--- a/guava/src/com/google/common/collect/ForwardingSortedMultiset.java
+++ b/guava/src/com/google/common/collect/ForwardingSortedMultiset.java
@@ -19,6 +19,8 @@
 import java.util.Comparator;
 import java.util.Iterator;
 import java.util.NavigableSet;
+import javax.annotation.CheckForNull;
+import org.checkerframework.checker.nullness.qual.Nullable;
 
 /**
  * A sorted multiset which forwards all its method calls to another sorted multiset. Subclasses
@@ -44,8 +46,9 @@
  */
 @Beta
 @GwtCompatible(emulated = true)
-public abstract class ForwardingSortedMultiset<E> extends ForwardingMultiset<E>
-    implements SortedMultiset<E> {
+@ElementTypesAreNonnullByDefault
+public abstract class ForwardingSortedMultiset<E extends @Nullable Object>
+    extends ForwardingMultiset<E> implements SortedMultiset<E> {
   /** Constructor for use by subclasses. */
   protected ForwardingSortedMultiset() {}
 
@@ -110,6 +113,7 @@ SortedMultiset<E> forwardMultiset() {
   }
 
   @Override
+  @CheckForNull
   public Entry<E> firstEntry() {
     return delegate().firstEntry();
   }
@@ -120,6 +124,7 @@ public Entry<E> firstEntry() {
    * <p>If you override {@link #entrySet()}, you may wish to override {@link #firstEntry()} to
    * forward to this implementation.
    */
+  @CheckForNull
   protected Entry<E> standardFirstEntry() {
     Iterator<Entry<E>> entryIterator = entrySet().iterator();
     if (!entryIterator.hasNext()) {
@@ -130,6 +135,7 @@ protected Entry<E> standardFirstEntry() {
   }
 
   @Override
+  @CheckForNull
   public Entry<E> lastEntry() {
     return delegate().lastEntry();
   }
@@ -141,6 +147,7 @@ public Entry<E> lastEntry() {
    * <p>If you override {@link #descendingMultiset} or {@link #entrySet()}, you may wish to override
    * {@link #firstEntry()} to forward to this implementation.
    */
+  @CheckForNull
   protected Entry<E> standardLastEntry() {
     Iterator<Entry<E>> entryIterator = descendingMultiset().entrySet().iterator();
     if (!entryIterator.hasNext()) {
@@ -151,6 +158,7 @@ protected Entry<E> standardLastEntry() {
   }
 
   @Override
+  @CheckForNull
   public Entry<E> pollFirstEntry() {
     return delegate().pollFirstEntry();
   }
@@ -161,6 +169,7 @@ public Entry<E> pollFirstEntry() {
    * <p>If you override {@link #entrySet()}, you may wish to override {@link #pollFirstEntry()} to
    * forward to this implementation.
    */
+  @CheckForNull
   protected Entry<E> standardPollFirstEntry() {
     Iterator<Entry<E>> entryIterator = entrySet().iterator();
     if (!entryIterator.hasNext()) {
@@ -173,6 +182,7 @@ protected Entry<E> standardPollFirstEntry() {
   }
 
   @Override
+  @CheckForNull
   public Entry<E> pollLastEntry() {
     return delegate().pollLastEntry();
   }
@@ -184,6 +194,7 @@ public Entry<E> pollLastEntry() {
    * <p>If you override {@link #descendingMultiset()} or {@link #entrySet()}, you may wish to
    * override {@link #pollLastEntry()} to forward to this implementation.
    */
+  @CheckForNull
   protected Entry<E> standardPollLastEntry() {
     Iterator<Entry<E>> entryIterator = descendingMultiset().entrySet().iterator();
     if (!entryIterator.hasNext()) {
@@ -196,13 +207,16 @@ protected Entry<E> standardPollLastEntry() {
   }
 
   @Override
-  public SortedMultiset<E> headMultiset(E upperBound, BoundType boundType) {
+  public SortedMultiset<E> headMultiset(@ParametricNullness E upperBound, BoundType boundType) {
     return delegate().headMultiset(upperBound, boundType);
   }
 
   @Override
   public SortedMultiset<E> subMultiset(
-      E lowerBound, BoundType lowerBoundType, E upperBound, BoundType upperBoundType) {
+      @ParametricNullness E lowerBound,
+      BoundType lowerBoundType,
+      @ParametricNullness E upperBound,
+      BoundType upperBoundType) {
     return delegate().subMultiset(lowerBound, lowerBoundType, upperBound, upperBoundType);
   }
 
@@ -215,12 +229,15 @@ public SortedMultiset<E> subMultiset(
    * #subMultiset(Object, BoundType, Object, BoundType)} to forward to this implementation.
    */
   protected SortedMultiset<E> standardSubMultiset(
-      E lowerBound, BoundType lowerBoundType, E upperBound, BoundType upperBoundType) {
+      @ParametricNullness E lowerBound,
+      BoundType lowerBoundType,
+      @ParametricNullness E upperBound,
+      BoundType upperBoundType) {
     return tailMultiset(lowerBound, lowerBoundType).headMultiset(upperBound, upperBoundType);
   }
 
   @Override
-  public SortedMultiset<E> tailMultiset(E lowerBound, BoundType boundType) {
+  public SortedMultiset<E> tailMultiset(@ParametricNullness E lowerBound, BoundType boundType) {
     return delegate().tailMultiset(lowerBound, boundType);
   }
 }
diff --git a/guava/src/com/google/common/collect/ForwardingSortedSet.java b/guava/src/com/google/common/collect/ForwardingSortedSet.java
index 4fd183fcb539..ede284ebf738 100644
--- a/guava/src/com/google/common/collect/ForwardingSortedSet.java
+++ b/guava/src/com/google/common/collect/ForwardingSortedSet.java
@@ -16,12 +16,15 @@
 
 package com.google.common.collect;
 
+import static com.google.common.collect.ForwardingSortedMap.unsafeCompare;
+
 import com.google.common.annotations.Beta;
 import com.google.common.annotations.GwtCompatible;
 import java.util.Comparator;
 import java.util.Iterator;
 import java.util.NoSuchElementException;
 import java.util.SortedSet;
+import javax.annotation.CheckForNull;
 import org.checkerframework.checker.nullness.qual.Nullable;
 import org.checkerframework.dataflow.qual.SideEffectFree;
 import org.checkerframework.framework.qual.AnnotatedFor;
@@ -55,7 +58,9 @@
  */
 @AnnotatedFor({"nullness"})
 @GwtCompatible
-public abstract class ForwardingSortedSet<E> extends ForwardingSet<E> implements SortedSet<E> {
+@ElementTypesAreNonnullByDefault
+public abstract class ForwardingSortedSet<E extends @Nullable Object> extends ForwardingSet<E>
+    implements SortedSet<E> {
 
   /** Constructor for use by subclasses. */
   protected ForwardingSortedSet() {}
@@ -65,49 +70,43 @@ protected ForwardingSortedSet() {}
 
   @SideEffectFree
   @Override
+  @CheckForNull
   public Comparator<? super E> comparator() {
     return delegate().comparator();
   }
 
   @SideEffectFree
   @Override
+  @ParametricNullness
   public E first() {
     return delegate().first();
   }
 
   @SideEffectFree
   @Override
-  public SortedSet<E> headSet(E toElement) {
+  public SortedSet<E> headSet(@ParametricNullness E toElement) {
     return delegate().headSet(toElement);
   }
 
   @SideEffectFree
   @Override
+  @ParametricNullness
   public E last() {
     return delegate().last();
   }
 
   @SideEffectFree
   @Override
-  public SortedSet<E> subSet(E fromElement, E toElement) {
+  public SortedSet<E> subSet(@ParametricNullness E fromElement, @ParametricNullness E toElement) {
     return delegate().subSet(fromElement, toElement);
   }
 
   @SideEffectFree
   @Override
-  public SortedSet<E> tailSet(E fromElement) {
+  public SortedSet<E> tailSet(@ParametricNullness E fromElement) {
     return delegate().tailSet(fromElement);
   }
 
-  // unsafe, but worst case is a CCE is thrown, which callers will be expecting
-  @SuppressWarnings("unchecked")
-  private int unsafeCompare(@Nullable Object o1, @Nullable Object o2) {
-    Comparator<? super E> comparator = comparator();
-    return (comparator == null)
-        ? ((Comparable<Object>) o1).compareTo(o2)
-        : ((Comparator<Object>) comparator).compare(o1, o2);
-  }
-
   /**
    * A sensible definition of {@link #contains} in terms of the {@code first()} method of {@link
    * #tailSet}. If you override {@link #tailSet}, you may wish to override {@link #contains} to
@@ -117,13 +116,13 @@ private int unsafeCompare(@Nullable Object o1, @Nullable Object o2) {
    */
   @Override
   @Beta
-  protected boolean standardContains(@Nullable Object object) {
+  protected boolean standardContains(@CheckForNull Object object) {
     try {
-      // any ClassCastExceptions are caught
-      @SuppressWarnings("unchecked")
-      SortedSet<Object> self = (SortedSet<Object>) this;
+      // any ClassCastExceptions and NullPointerExceptions are caught
+      @SuppressWarnings({"unchecked", "nullness"})
+      SortedSet<@Nullable Object> self = (SortedSet<@Nullable Object>) this;
       Object ceiling = self.tailSet(object).first();
-      return unsafeCompare(ceiling, object) == 0;
+      return unsafeCompare(comparator(), ceiling, object) == 0;
     } catch (ClassCastException | NoSuchElementException | NullPointerException e) {
       return false;
     }
@@ -138,15 +137,15 @@ protected boolean standardContains(@Nullable Object object) {
    */
   @Override
   @Beta
-  protected boolean standardRemove(@Nullable Object object) {
+  protected boolean standardRemove(@CheckForNull Object object) {
     try {
-      // any ClassCastExceptions are caught
-      @SuppressWarnings("unchecked")
-      SortedSet<Object> self = (SortedSet<Object>) this;
-      Iterator<Object> iterator = self.tailSet(object).iterator();
+      // any ClassCastExceptions and NullPointerExceptions are caught
+      @SuppressWarnings({"unchecked", "nullness"})
+      SortedSet<@Nullable Object> self = (SortedSet<@Nullable Object>) this;
+      Iterator<?> iterator = self.tailSet(object).iterator();
       if (iterator.hasNext()) {
         Object ceiling = iterator.next();
-        if (unsafeCompare(ceiling, object) == 0) {
+        if (unsafeCompare(comparator(), ceiling, object) == 0) {
           iterator.remove();
           return true;
         }
@@ -165,7 +164,8 @@ protected boolean standardRemove(@Nullable Object object) {
    * @since 7.0
    */
   @Beta
-  protected SortedSet<E> standardSubSet(E fromElement, E toElement) {
+  protected SortedSet<E> standardSubSet(
+      @ParametricNullness E fromElement, @ParametricNullness E toElement) {
     return tailSet(fromElement).headSet(toElement);
   }
 }
diff --git a/guava/src/com/google/common/collect/ForwardingSortedSetMultimap.java b/guava/src/com/google/common/collect/ForwardingSortedSetMultimap.java
index 546eb477e942..b91a68b3445a 100644
--- a/guava/src/com/google/common/collect/ForwardingSortedSetMultimap.java
+++ b/guava/src/com/google/common/collect/ForwardingSortedSetMultimap.java
@@ -19,6 +19,7 @@
 import com.google.common.annotations.GwtCompatible;
 import java.util.Comparator;
 import java.util.SortedSet;
+import javax.annotation.CheckForNull;
 import org.checkerframework.checker.nullness.qual.Nullable;
 
 /**
@@ -34,8 +35,10 @@
  * @since 3.0
  */
 @GwtCompatible
-public abstract class ForwardingSortedSetMultimap<K, V> extends ForwardingSetMultimap<K, V>
-    implements SortedSetMultimap<K, V> {
+@ElementTypesAreNonnullByDefault
+public abstract class ForwardingSortedSetMultimap<
+        K extends @Nullable Object, V extends @Nullable Object>
+    extends ForwardingSetMultimap<K, V> implements SortedSetMultimap<K, V> {
 
   /** Constructor for use by subclasses. */
   protected ForwardingSortedSetMultimap() {}
@@ -44,21 +47,22 @@ protected ForwardingSortedSetMultimap() {}
   protected abstract SortedSetMultimap<K, V> delegate();
 
   @Override
-  public SortedSet<V> get(@Nullable K key) {
+  public SortedSet<V> get(@ParametricNullness K key) {
     return delegate().get(key);
   }
 
   @Override
-  public SortedSet<V> removeAll(@Nullable Object key) {
+  public SortedSet<V> removeAll(@CheckForNull Object key) {
     return delegate().removeAll(key);
   }
 
   @Override
-  public SortedSet<V> replaceValues(K key, Iterable<? extends V> values) {
+  public SortedSet<V> replaceValues(@ParametricNullness K key, Iterable<? extends V> values) {
     return delegate().replaceValues(key, values);
   }
 
   @Override
+  @CheckForNull
   public Comparator<? super V> valueComparator() {
     return delegate().valueComparator();
   }
diff --git a/guava/src/com/google/common/collect/ForwardingTable.java b/guava/src/com/google/common/collect/ForwardingTable.java
index 71a54cfbcfea..4fcb858b725f 100644
--- a/guava/src/com/google/common/collect/ForwardingTable.java
+++ b/guava/src/com/google/common/collect/ForwardingTable.java
@@ -21,6 +21,8 @@
 import java.util.Collection;
 import java.util.Map;
 import java.util.Set;
+import javax.annotation.CheckForNull;
+import org.checkerframework.checker.nullness.qual.Nullable;
 
 /**
  * A table which forwards all its method calls to another table. Subclasses should override one or
@@ -31,7 +33,10 @@
  * @since 7.0
  */
 @GwtCompatible
-public abstract class ForwardingTable<R, C, V> extends ForwardingObject implements Table<R, C, V> {
+@ElementTypesAreNonnullByDefault
+public abstract class ForwardingTable<
+        R extends @Nullable Object, C extends @Nullable Object, V extends @Nullable Object>
+    extends ForwardingObject implements Table<R, C, V> {
   /** Constructor for use by subclasses. */
   protected ForwardingTable() {}
 
@@ -49,7 +54,7 @@ public void clear() {
   }
 
   @Override
-  public Map<R, V> column(C columnKey) {
+  public Map<R, V> column(@ParametricNullness C columnKey) {
     return delegate().column(columnKey);
   }
 
@@ -64,27 +69,28 @@ public Map<C, Map<R, V>> columnMap() {
   }
 
   @Override
-  public boolean contains(Object rowKey, Object columnKey) {
+  public boolean contains(@CheckForNull Object rowKey, @CheckForNull Object columnKey) {
     return delegate().contains(rowKey, columnKey);
   }
 
   @Override
-  public boolean containsColumn(Object columnKey) {
+  public boolean containsColumn(@CheckForNull Object columnKey) {
     return delegate().containsColumn(columnKey);
   }
 
   @Override
-  public boolean containsRow(Object rowKey) {
+  public boolean containsRow(@CheckForNull Object rowKey) {
     return delegate().containsRow(rowKey);
   }
 
   @Override
-  public boolean containsValue(Object value) {
+  public boolean containsValue(@CheckForNull Object value) {
     return delegate().containsValue(value);
   }
 
   @Override
-  public V get(Object rowKey, Object columnKey) {
+  @CheckForNull
+  public V get(@CheckForNull Object rowKey, @CheckForNull Object columnKey) {
     return delegate().get(rowKey, columnKey);
   }
 
@@ -95,7 +101,9 @@ public boolean isEmpty() {
 
   @CanIgnoreReturnValue
   @Override
-  public V put(R rowKey, C columnKey, V value) {
+  @CheckForNull
+  public V put(
+      @ParametricNullness R rowKey, @ParametricNullness C columnKey, @ParametricNullness V value) {
     return delegate().put(rowKey, columnKey, value);
   }
 
@@ -106,12 +114,13 @@ public void putAll(Table<? extends R, ? extends C, ? extends V> table) {
 
   @CanIgnoreReturnValue
   @Override
-  public V remove(Object rowKey, Object columnKey) {
+  @CheckForNull
+  public V remove(@CheckForNull Object rowKey, @CheckForNull Object columnKey) {
     return delegate().remove(rowKey, columnKey);
   }
 
   @Override
-  public Map<C, V> row(R rowKey) {
+  public Map<C, V> row(@ParametricNullness R rowKey) {
     return delegate().row(rowKey);
   }
 
@@ -136,7 +145,7 @@ public Collection<V> values() {
   }
 
   @Override
-  public boolean equals(Object obj) {
+  public boolean equals(@CheckForNull Object obj) {
     return (obj == this) || delegate().equals(obj);
   }
 
diff --git a/guava/src/com/google/common/collect/GeneralRange.java b/guava/src/com/google/common/collect/GeneralRange.java
index 1ce5659239bb..3d7256ff811f 100644
--- a/guava/src/com/google/common/collect/GeneralRange.java
+++ b/guava/src/com/google/common/collect/GeneralRange.java
@@ -18,11 +18,13 @@
 import static com.google.common.base.Preconditions.checkNotNull;
 import static com.google.common.collect.BoundType.CLOSED;
 import static com.google.common.collect.BoundType.OPEN;
+import static com.google.common.collect.NullnessCasts.uncheckedCastNullableTToT;
 
 import com.google.common.annotations.GwtCompatible;
 import com.google.common.base.Objects;
 import java.io.Serializable;
 import java.util.Comparator;
+import javax.annotation.CheckForNull;
 import org.checkerframework.checker.nullness.qual.Nullable;
 
 /**
@@ -35,15 +37,16 @@
  * @author Louis Wasserman
  */
 @GwtCompatible(serializable = true)
-final class GeneralRange<T> implements Serializable {
+@ElementTypesAreNonnullByDefault
+final class GeneralRange<T extends @Nullable Object> implements Serializable {
   /** Converts a Range to a GeneralRange. */
   static <T extends Comparable> GeneralRange<T> from(Range<T> range) {
-    @Nullable T lowerEndpoint = range.hasLowerBound() ? range.lowerEndpoint() : null;
+    T lowerEndpoint = range.hasLowerBound() ? range.lowerEndpoint() : null;
     BoundType lowerBoundType = range.hasLowerBound() ? range.lowerBoundType() : OPEN;
 
-    @Nullable T upperEndpoint = range.hasUpperBound() ? range.upperEndpoint() : null;
+    T upperEndpoint = range.hasUpperBound() ? range.upperEndpoint() : null;
     BoundType upperBoundType = range.hasUpperBound() ? range.upperBoundType() : OPEN;
-    return new GeneralRange<T>(
+    return new GeneralRange<>(
         Ordering.natural(),
         range.hasLowerBound(),
         lowerEndpoint,
@@ -54,56 +57,56 @@ static <T extends Comparable> GeneralRange<T> from(Range<T> range) {
   }
 
   /** Returns the whole range relative to the specified comparator. */
-  static <T> GeneralRange<T> all(Comparator<? super T> comparator) {
-    return new GeneralRange<T>(comparator, false, null, OPEN, false, null, OPEN);
+  static <T extends @Nullable Object> GeneralRange<T> all(Comparator<? super T> comparator) {
+    return new GeneralRange<>(comparator, false, null, OPEN, false, null, OPEN);
   }
 
   /**
    * Returns everything above the endpoint relative to the specified comparator, with the specified
    * endpoint behavior.
    */
-  static <T> GeneralRange<T> downTo(
-      Comparator<? super T> comparator, @Nullable T endpoint, BoundType boundType) {
-    return new GeneralRange<T>(comparator, true, endpoint, boundType, false, null, OPEN);
+  static <T extends @Nullable Object> GeneralRange<T> downTo(
+      Comparator<? super T> comparator, @ParametricNullness T endpoint, BoundType boundType) {
+    return new GeneralRange<>(comparator, true, endpoint, boundType, false, null, OPEN);
   }
 
   /**
    * Returns everything below the endpoint relative to the specified comparator, with the specified
    * endpoint behavior.
    */
-  static <T> GeneralRange<T> upTo(
-      Comparator<? super T> comparator, @Nullable T endpoint, BoundType boundType) {
-    return new GeneralRange<T>(comparator, false, null, OPEN, true, endpoint, boundType);
+  static <T extends @Nullable Object> GeneralRange<T> upTo(
+      Comparator<? super T> comparator, @ParametricNullness T endpoint, BoundType boundType) {
+    return new GeneralRange<>(comparator, false, null, OPEN, true, endpoint, boundType);
   }
 
   /**
    * Returns everything between the endpoints relative to the specified comparator, with the
    * specified endpoint behavior.
    */
-  static <T> GeneralRange<T> range(
+  static <T extends @Nullable Object> GeneralRange<T> range(
       Comparator<? super T> comparator,
-      @Nullable T lower,
+      @ParametricNullness T lower,
       BoundType lowerType,
-      @Nullable T upper,
+      @ParametricNullness T upper,
       BoundType upperType) {
-    return new GeneralRange<T>(comparator, true, lower, lowerType, true, upper, upperType);
+    return new GeneralRange<>(comparator, true, lower, lowerType, true, upper, upperType);
   }
 
   private final Comparator<? super T> comparator;
   private final boolean hasLowerBound;
-  private final @Nullable T lowerEndpoint;
+  @CheckForNull private final T lowerEndpoint;
   private final BoundType lowerBoundType;
   private final boolean hasUpperBound;
-  private final @Nullable T upperEndpoint;
+  @CheckForNull private final T upperEndpoint;
   private final BoundType upperBoundType;
 
   private GeneralRange(
       Comparator<? super T> comparator,
       boolean hasLowerBound,
-      @Nullable T lowerEndpoint,
+      @CheckForNull T lowerEndpoint,
       BoundType lowerBoundType,
       boolean hasUpperBound,
-      @Nullable T upperEndpoint,
+      @CheckForNull T upperEndpoint,
       BoundType upperBoundType) {
     this.comparator = checkNotNull(comparator);
     this.hasLowerBound = hasLowerBound;
@@ -113,19 +116,29 @@ private GeneralRange(
     this.upperEndpoint = upperEndpoint;
     this.upperBoundType = checkNotNull(upperBoundType);
 
+    // Trigger any exception that the comparator would throw for the endpoints.
+    /*
+     * uncheckedCastNullableTToT is safe as long as the callers are careful to pass a "real" T
+     * whenever they pass `true` for the matching `has*Bound` parameter.
+     */
     if (hasLowerBound) {
-      comparator.compare(lowerEndpoint, lowerEndpoint);
+      comparator.compare(
+          uncheckedCastNullableTToT(lowerEndpoint), uncheckedCastNullableTToT(lowerEndpoint));
     }
     if (hasUpperBound) {
-      comparator.compare(upperEndpoint, upperEndpoint);
+      comparator.compare(
+          uncheckedCastNullableTToT(upperEndpoint), uncheckedCastNullableTToT(upperEndpoint));
     }
+
     if (hasLowerBound && hasUpperBound) {
-      int cmp = comparator.compare(lowerEndpoint, upperEndpoint);
+      int cmp =
+          comparator.compare(
+              uncheckedCastNullableTToT(lowerEndpoint), uncheckedCastNullableTToT(upperEndpoint));
       // be consistent with Range
       checkArgument(
           cmp <= 0, "lowerEndpoint (%s) > upperEndpoint (%s)", lowerEndpoint, upperEndpoint);
       if (cmp == 0) {
-        checkArgument(lowerBoundType != OPEN | upperBoundType != OPEN);
+        checkArgument(lowerBoundType != OPEN || upperBoundType != OPEN);
       }
     }
   }
@@ -143,41 +156,45 @@ boolean hasUpperBound() {
   }
 
   boolean isEmpty() {
-    return (hasUpperBound() && tooLow(getUpperEndpoint()))
-        || (hasLowerBound() && tooHigh(getLowerEndpoint()));
+    // The casts are safe because of the has*Bound() checks.
+    return (hasUpperBound() && tooLow(uncheckedCastNullableTToT(getUpperEndpoint())))
+        || (hasLowerBound() && tooHigh(uncheckedCastNullableTToT(getLowerEndpoint())));
   }
 
-  boolean tooLow(@Nullable T t) {
+  boolean tooLow(@ParametricNullness T t) {
     if (!hasLowerBound()) {
       return false;
     }
-    T lbound = getLowerEndpoint();
+    // The cast is safe because of the hasLowerBound() check.
+    T lbound = uncheckedCastNullableTToT(getLowerEndpoint());
     int cmp = comparator.compare(t, lbound);
     return cmp < 0 | (cmp == 0 & getLowerBoundType() == OPEN);
   }
 
-  boolean tooHigh(@Nullable T t) {
+  boolean tooHigh(@ParametricNullness T t) {
     if (!hasUpperBound()) {
       return false;
     }
-    T ubound = getUpperEndpoint();
+    // The cast is safe because of the hasUpperBound() check.
+    T ubound = uncheckedCastNullableTToT(getUpperEndpoint());
     int cmp = comparator.compare(t, ubound);
     return cmp > 0 | (cmp == 0 & getUpperBoundType() == OPEN);
   }
 
-  boolean contains(@Nullable T t) {
+  boolean contains(@ParametricNullness T t) {
     return !tooLow(t) && !tooHigh(t);
   }
 
   /**
    * Returns the intersection of the two ranges, or an empty range if their intersection is empty.
    */
+  @SuppressWarnings("nullness") // TODO(cpovirk): Add casts as needed. Will be noisy and annoying...
   GeneralRange<T> intersect(GeneralRange<T> other) {
     checkNotNull(other);
     checkArgument(comparator.equals(other.comparator));
 
     boolean hasLowBound = this.hasLowerBound;
-    @Nullable T lowEnd = getLowerEndpoint();
+    T lowEnd = getLowerEndpoint();
     BoundType lowType = getLowerBoundType();
     if (!hasLowerBound()) {
       hasLowBound = other.hasLowerBound;
@@ -192,7 +209,7 @@ GeneralRange<T> intersect(GeneralRange<T> other) {
     }
 
     boolean hasUpBound = this.hasUpperBound;
-    @Nullable T upEnd = getUpperEndpoint();
+    T upEnd = getUpperEndpoint();
     BoundType upType = getUpperBoundType();
     if (!hasUpperBound()) {
       hasUpBound = other.hasUpperBound;
@@ -216,11 +233,11 @@ GeneralRange<T> intersect(GeneralRange<T> other) {
       }
     }
 
-    return new GeneralRange<T>(comparator, hasLowBound, lowEnd, lowType, hasUpBound, upEnd, upType);
+    return new GeneralRange<>(comparator, hasLowBound, lowEnd, lowType, hasUpBound, upEnd, upType);
   }
 
   @Override
-  public boolean equals(@Nullable Object obj) {
+  public boolean equals(@CheckForNull Object obj) {
     if (obj instanceof GeneralRange) {
       GeneralRange<?> r = (GeneralRange<?>) obj;
       return comparator.equals(r.comparator)
@@ -244,14 +261,14 @@ public int hashCode() {
         getUpperBoundType());
   }
 
-  private transient @Nullable GeneralRange<T> reverse;
+  @CheckForNull private transient GeneralRange<T> reverse;
 
   /** Returns the same range relative to the reversed comparator. */
   GeneralRange<T> reverse() {
     GeneralRange<T> result = reverse;
     if (result == null) {
       result =
-          new GeneralRange<T>(
+          new GeneralRange<>(
               Ordering.from(comparator).reverse(),
               hasUpperBound,
               getUpperEndpoint(),
@@ -276,6 +293,7 @@ public String toString() {
         + (upperBoundType == CLOSED ? ']' : ')');
   }
 
+  @CheckForNull
   T getLowerEndpoint() {
     return lowerEndpoint;
   }
@@ -284,6 +302,7 @@ BoundType getLowerBoundType() {
     return lowerBoundType;
   }
 
+  @CheckForNull
   T getUpperEndpoint() {
     return upperEndpoint;
   }
diff --git a/guava/src/com/google/common/collect/GwtTransient.java b/guava/src/com/google/common/collect/GwtTransient.java
index 9c09c53c946f..ce5ea48848c9 100644
--- a/guava/src/com/google/common/collect/GwtTransient.java
+++ b/guava/src/com/google/common/collect/GwtTransient.java
@@ -33,4 +33,5 @@
 @GwtCompatible
 @Retention(RUNTIME)
 @Target(FIELD)
+@ElementTypesAreNonnullByDefault
 @interface GwtTransient {}
diff --git a/guava/src/com/google/common/collect/HashBasedTable.java b/guava/src/com/google/common/collect/HashBasedTable.java
index 8f6df57808e6..21882e62d406 100644
--- a/guava/src/com/google/common/collect/HashBasedTable.java
+++ b/guava/src/com/google/common/collect/HashBasedTable.java
@@ -20,11 +20,9 @@
 
 import com.google.common.annotations.GwtCompatible;
 import com.google.common.base.Supplier;
-import com.google.errorprone.annotations.CanIgnoreReturnValue;
 import java.io.Serializable;
 import java.util.LinkedHashMap;
 import java.util.Map;
-import org.checkerframework.checker.nullness.qual.Nullable;
 
 /**
  * Implementation of {@link Table} using linked hash tables. This guarantees predictable iteration
@@ -43,12 +41,13 @@
  * concurrently and one of the threads modifies the table, it must be synchronized externally.
  *
  * <p>See the Guava User Guide article on <a href=
- * "https://github.com/google/guava/wiki/NewCollectionTypesExplained#table"> {@code Table}</a>.
+ * "https://github.com/google/guava/wiki/NewCollectionTypesExplained#table">{@code Table}</a>.
  *
  * @author Jared Levy
  * @since 7.0
  */
 @GwtCompatible(serializable = true)
+@ElementTypesAreNonnullByDefault
 public class HashBasedTable<R, C, V> extends StandardTable<R, C, V> {
   private static class Factory<C, V> implements Supplier<Map<C, V>>, Serializable {
     final int expectedSize;
@@ -103,43 +102,5 @@ public static <R, C, V> HashBasedTable<R, C, V> create(
     super(backingMap, factory);
   }
 
-  // Overriding so NullPointerTester test passes.
-
-  @Override
-  public boolean contains(@Nullable Object rowKey, @Nullable Object columnKey) {
-    return super.contains(rowKey, columnKey);
-  }
-
-  @Override
-  public boolean containsColumn(@Nullable Object columnKey) {
-    return super.containsColumn(columnKey);
-  }
-
-  @Override
-  public boolean containsRow(@Nullable Object rowKey) {
-    return super.containsRow(rowKey);
-  }
-
-  @Override
-  public boolean containsValue(@Nullable Object value) {
-    return super.containsValue(value);
-  }
-
-  @Override
-  public V get(@Nullable Object rowKey, @Nullable Object columnKey) {
-    return super.get(rowKey, columnKey);
-  }
-
-  @Override
-  public boolean equals(@Nullable Object obj) {
-    return super.equals(obj);
-  }
-
-  @CanIgnoreReturnValue
-  @Override
-  public V remove(@Nullable Object rowKey, @Nullable Object columnKey) {
-    return super.remove(rowKey, columnKey);
-  }
-
   private static final long serialVersionUID = 0;
 }
diff --git a/guava/src/com/google/common/collect/HashBiMap.java b/guava/src/com/google/common/collect/HashBiMap.java
index f0a348c7ae22..51d6e0cf3265 100644
--- a/guava/src/com/google/common/collect/HashBiMap.java
+++ b/guava/src/com/google/common/collect/HashBiMap.java
@@ -17,8 +17,8 @@
 import static com.google.common.base.Preconditions.checkArgument;
 import static com.google.common.base.Preconditions.checkNotNull;
 import static com.google.common.collect.CollectPreconditions.checkNonnegative;
-import static com.google.common.collect.CollectPreconditions.checkRemove;
 import static com.google.common.collect.Hashing.smearedHash;
+import static java.util.Objects.requireNonNull;
 
 import com.google.common.annotations.GwtCompatible;
 import com.google.common.annotations.GwtIncompatible;
@@ -40,6 +40,7 @@
 import java.util.Set;
 import java.util.function.BiConsumer;
 import java.util.function.BiFunction;
+import javax.annotation.CheckForNull;
 import org.checkerframework.checker.nullness.qual.Nullable;
 import org.checkerframework.dataflow.qual.Pure;
 import org.checkerframework.dataflow.qual.SideEffectFree;
@@ -52,7 +53,7 @@
  * <p>This implementation guarantees insertion-based iteration order of its keys.
  *
  * <p>See the Guava User Guide article on <a href=
- * "https://github.com/google/guava/wiki/NewCollectionTypesExplained#bimap"> {@code BiMap} </a>.
+ * "https://github.com/google/guava/wiki/NewCollectionTypesExplained#bimap">{@code BiMap} </a>.
  *
  * @author Louis Wasserman
  * @author Mike Bostock
@@ -60,11 +61,12 @@
  */
 @AnnotatedFor({"nullness"})
 @GwtCompatible(emulated = true)
-public final class HashBiMap<K, V> extends IteratorBasedAbstractMap<K, V>
-    implements BiMap<K, V>, Serializable {
+@ElementTypesAreNonnullByDefault
+public final class HashBiMap<K extends @Nullable Object, V extends @Nullable Object>
+    extends IteratorBasedAbstractMap<K, V> implements BiMap<K, V>, Serializable {
 
   /** Returns a new, empty {@code HashBiMap} with the default initial capacity (16). */
-  public static <K, V> HashBiMap<K, V> create() {
+  public static <K extends @Nullable Object, V extends @Nullable Object> HashBiMap<K, V> create() {
     return create(16);
   }
 
@@ -74,7 +76,8 @@ public static <K, V> HashBiMap<K, V> create() {
    * @param expectedSize the expected number of entries
    * @throws IllegalArgumentException if the specified expected size is negative
    */
-  public static <K, V> HashBiMap<K, V> create(int expectedSize) {
+  public static <K extends @Nullable Object, V extends @Nullable Object> HashBiMap<K, V> create(
+      int expectedSize) {
     return new HashBiMap<>(expectedSize);
   }
 
@@ -82,13 +85,15 @@ public static <K, V> HashBiMap<K, V> create(int expectedSize) {
    * Constructs a new bimap containing initial values from {@code map}. The bimap is created with an
    * initial capacity sufficient to hold the mappings in the specified map.
    */
-  public static <K, V> HashBiMap<K, V> create(Map<? extends K, ? extends V> map) {
+  public static <K extends @Nullable Object, V extends @Nullable Object> HashBiMap<K, V> create(
+      Map<? extends K, ? extends V> map) {
     HashBiMap<K, V> bimap = create(map.size());
     bimap.putAll(map);
     return bimap;
   }
 
-  private static final class BiEntry<K, V> extends ImmutableEntry<K, V> {
+  private static final class BiEntry<K extends @Nullable Object, V extends @Nullable Object>
+      extends ImmutableEntry<K, V> {
     final int keyHash;
     final int valueHash;
 
@@ -98,13 +103,13 @@ private static final class BiEntry<K, V> extends ImmutableEntry<K, V> {
     // Using @Weak is necessary to avoid retain-cycles between BiEntry instances on iOS,
     // which would cause memory leaks when non-empty HashBiMap with cyclic BiEntry
     // instances is deallocated.
-    @Nullable BiEntry<K, V> nextInKToVBucket;
-    @Weak @Nullable BiEntry<K, V> nextInVToKBucket;
+    @CheckForNull BiEntry<K, V> nextInKToVBucket;
+    @Weak @CheckForNull BiEntry<K, V> nextInVToKBucket;
 
-    @Weak @Nullable BiEntry<K, V> nextInKeyInsertionOrder;
-    @Weak @Nullable BiEntry<K, V> prevInKeyInsertionOrder;
+    @Weak @CheckForNull BiEntry<K, V> nextInKeyInsertionOrder;
+    @Weak @CheckForNull BiEntry<K, V> prevInKeyInsertionOrder;
 
-    BiEntry(K key, int keyHash, V value, int valueHash) {
+    BiEntry(@ParametricNullness K key, int keyHash, @ParametricNullness V value, int valueHash) {
       super(key, value);
       this.keyHash = keyHash;
       this.valueHash = valueHash;
@@ -113,10 +118,15 @@ private static final class BiEntry<K, V> extends ImmutableEntry<K, V> {
 
   private static final double LOAD_FACTOR = 1.0;
 
-  private transient BiEntry<K, V>[] hashTableKToV;
-  private transient BiEntry<K, V>[] hashTableVToK;
-  @Weak private transient @Nullable BiEntry<K, V> firstInKeyInsertionOrder;
-  @Weak private transient @Nullable BiEntry<K, V> lastInKeyInsertionOrder;
+  /*
+   * The following two arrays may *contain* nulls, but they are never *themselves* null: Even though
+   * they are not initialized inline in the constructor, they are initialized from init(), which the
+   * constructor calls (as does readObject()).
+   */
+  private transient @Nullable BiEntry<K, V>[] hashTableKToV;
+  private transient @Nullable BiEntry<K, V>[] hashTableVToK;
+  @Weak @CheckForNull private transient BiEntry<K, V> firstInKeyInsertionOrder;
+  @Weak @CheckForNull private transient BiEntry<K, V> lastInKeyInsertionOrder;
   private transient int size;
   private transient int mask;
   private transient int modCount;
@@ -190,7 +200,7 @@ private void delete(BiEntry<K, V> entry) {
     modCount++;
   }
 
-  private void insert(BiEntry<K, V> entry, @Nullable BiEntry<K, V> oldEntryForKey) {
+  private void insert(BiEntry<K, V> entry, @CheckForNull BiEntry<K, V> oldEntryForKey) {
     int keyBucket = entry.keyHash & mask;
     entry.nextInKToVBucket = hashTableKToV[keyBucket];
     hashTableKToV[keyBucket] = entry;
@@ -227,7 +237,8 @@ private void insert(BiEntry<K, V> entry, @Nullable BiEntry<K, V> oldEntryForKey)
     modCount++;
   }
 
-  private BiEntry<K, V> seekByKey(@Nullable Object key, int keyHash) {
+  @CheckForNull
+  private BiEntry<K, V> seekByKey(@CheckForNull Object key, int keyHash) {
     for (BiEntry<K, V> entry = hashTableKToV[keyHash & mask];
         entry != null;
         entry = entry.nextInKToVBucket) {
@@ -238,7 +249,8 @@ private BiEntry<K, V> seekByKey(@Nullable Object key, int keyHash) {
     return null;
   }
 
-  private BiEntry<K, V> seekByValue(@Nullable Object value, int valueHash) {
+  @CheckForNull
+  private BiEntry<K, V> seekByValue(@CheckForNull Object value, int valueHash) {
     for (BiEntry<K, V> entry = hashTableVToK[valueHash & mask];
         entry != null;
         entry = entry.nextInVToKBucket) {
@@ -250,7 +262,7 @@ private BiEntry<K, V> seekByValue(@Nullable Object value, int valueHash) {
   }
 
   @Override
-  public boolean containsKey(@Nullable Object key) {
+  public boolean containsKey(@CheckForNull Object key) {
     return seekByKey(key, smearedHash(key)) != null;
   }
 
@@ -266,22 +278,25 @@ public boolean containsKey(@Nullable Object key) {
    */
   @Pure
   @Override
-  public boolean containsValue(@Nullable Object value) {
+  public boolean containsValue(@CheckForNull Object value) {
     return seekByValue(value, smearedHash(value)) != null;
   }
 
   @Override
-  public @Nullable V get(@Nullable Object key) {
+  @CheckForNull
+  public V get(@CheckForNull Object key) {
     return Maps.valueOrNull(seekByKey(key, smearedHash(key)));
   }
 
   @CanIgnoreReturnValue
   @Override
-  public V put(@Nullable K key, @Nullable V value) {
+  @CheckForNull
+  public V put(@ParametricNullness K key, @ParametricNullness V value) {
     return put(key, value, false);
   }
 
-  private V put(@Nullable K key, @Nullable V value, boolean force) {
+  @CheckForNull
+  private V put(@ParametricNullness K key, @ParametricNullness V value, boolean force) {
     int keyHash = smearedHash(key);
     int valueHash = smearedHash(value);
 
@@ -317,11 +332,13 @@ private V put(@Nullable K key, @Nullable V value, boolean force) {
 
   @CanIgnoreReturnValue
   @Override
-  public @Nullable V forcePut(@Nullable K key, @Nullable V value) {
+  @CheckForNull
+  public V forcePut(@ParametricNullness K key, @ParametricNullness V value) {
     return put(key, value, true);
   }
 
-  private @Nullable K putInverse(@Nullable V value, @Nullable K key, boolean force) {
+  @CheckForNull
+  private K putInverse(@ParametricNullness V value, @ParametricNullness K key, boolean force) {
     int valueHash = smearedHash(value);
     int keyHash = smearedHash(key);
 
@@ -366,7 +383,7 @@ private V put(@Nullable K key, @Nullable V value, boolean force) {
   }
 
   private void rehashIfNecessary() {
-    BiEntry<K, V>[] oldKToV = hashTableKToV;
+    @Nullable BiEntry<K, V>[] oldKToV = hashTableKToV;
     if (Hashing.needsResizing(size, oldKToV.length, LOAD_FACTOR)) {
       int newTableSize = oldKToV.length * 2;
 
@@ -384,14 +401,15 @@ private void rehashIfNecessary() {
     }
   }
 
-  @SuppressWarnings("unchecked")
-  private BiEntry<K, V>[] createTable(int length) {
-    return new BiEntry[length];
+  @SuppressWarnings({"unchecked", "rawtypes"})
+  private @Nullable BiEntry<K, V>[] createTable(int length) {
+    return new @Nullable BiEntry[length];
   }
 
   @CanIgnoreReturnValue
   @Override
-  public @Nullable V remove(@Nullable Object key) {
+  @CheckForNull
+  public V remove(@CheckForNull Object key) {
     BiEntry<K, V> entry = seekByKey(key, smearedHash(key));
     if (entry == null) {
       return null;
@@ -418,9 +436,9 @@ public int size() {
     return size;
   }
 
-  abstract class Itr<T> implements Iterator<T> {
-    BiEntry<K, V> next = firstInKeyInsertionOrder;
-    BiEntry<K, V> toRemove = null;
+  abstract class Itr<T extends @Nullable Object> implements Iterator<T> {
+    @CheckForNull BiEntry<K, V> next = firstInKeyInsertionOrder;
+    @CheckForNull BiEntry<K, V> toRemove = null;
     int expectedModCount = modCount;
     int remaining = size();
 
@@ -438,7 +456,8 @@ public T next() {
         throw new NoSuchElementException();
       }
 
-      BiEntry<K, V> entry = next;
+      // requireNonNull is safe because of the hasNext check.
+      BiEntry<K, V> entry = requireNonNull(next);
       next = entry.nextInKeyInsertionOrder;
       toRemove = entry;
       remaining--;
@@ -450,7 +469,9 @@ public void remove() {
       if (modCount != expectedModCount) {
         throw new ConcurrentModificationException();
       }
-      checkRemove(toRemove != null);
+      if (toRemove == null) {
+        throw new IllegalStateException("no calls to next() since the last call to remove()");
+      }
       delete(toRemove);
       expectedModCount = modCount;
       toRemove = null;
@@ -473,6 +494,7 @@ private final class KeySet extends Maps.KeySet<K, V> {
     public Iterator<K> iterator() {
       return new Itr<K>() {
         @Override
+        @ParametricNullness
         K output(BiEntry<K, V> entry) {
           return entry.key;
         }
@@ -480,7 +502,7 @@ K output(BiEntry<K, V> entry) {
     }
 
     @Override
-    public boolean remove(@Nullable Object o) {
+    public boolean remove(@CheckForNull Object o) {
       BiEntry<K, V> entry = seekByKey(o, smearedHash(o));
       if (entry == null) {
         return false;
@@ -514,17 +536,20 @@ class MapEntry extends AbstractMapEntry<K, V> {
         }
 
         @Override
+        @ParametricNullness
         public K getKey() {
           return delegate.key;
         }
 
         @Override
+        @ParametricNullness
         public V getValue() {
           return delegate.value;
         }
 
         @Override
-        public V setValue(V value) {
+        @ParametricNullness
+        public V setValue(@ParametricNullness V value) {
           V oldValue = delegate.value;
           int valueHash = smearedHash(value);
           if (valueHash == delegate.valueHash && Objects.equal(value, oldValue)) {
@@ -567,7 +592,7 @@ public void replaceAll(BiFunction<? super K, ? super V, ? extends V> function) {
     }
   }
 
-  @LazyInit @RetainedWith private transient @Nullable BiMap<V, K> inverse;
+  @LazyInit @RetainedWith @CheckForNull private transient BiMap<V, K> inverse;
 
   @Override
   public BiMap<V, K> inverse() {
@@ -592,28 +617,32 @@ public void clear() {
     }
 
     @Override
-    public boolean containsKey(@Nullable Object value) {
+    public boolean containsKey(@CheckForNull Object value) {
       return forward().containsValue(value);
     }
 
     @Override
-    public K get(@Nullable Object value) {
+    @CheckForNull
+    public K get(@CheckForNull Object value) {
       return Maps.keyOrNull(seekByValue(value, smearedHash(value)));
     }
 
     @CanIgnoreReturnValue
     @Override
-    public @Nullable K put(@Nullable V value, @Nullable K key) {
+    @CheckForNull
+    public K put(@ParametricNullness V value, @ParametricNullness K key) {
       return putInverse(value, key, false);
     }
 
     @Override
-    public @Nullable K forcePut(@Nullable V value, @Nullable K key) {
+    @CheckForNull
+    public K forcePut(@ParametricNullness V value, @ParametricNullness K key) {
       return putInverse(value, key, true);
     }
 
     @Override
-    public @Nullable K remove(@Nullable Object value) {
+    @CheckForNull
+    public K remove(@CheckForNull Object value) {
       BiEntry<K, V> entry = seekByValue(value, smearedHash(value));
       if (entry == null) {
         return null;
@@ -641,7 +670,7 @@ private final class InverseKeySet extends Maps.KeySet<V, K> {
       }
 
       @Override
-      public boolean remove(@Nullable Object o) {
+      public boolean remove(@CheckForNull Object o) {
         BiEntry<K, V> entry = seekByValue(o, smearedHash(o));
         if (entry == null) {
           return false;
@@ -655,6 +684,7 @@ public boolean remove(@Nullable Object o) {
       public Iterator<V> iterator() {
         return new Itr<V>() {
           @Override
+          @ParametricNullness
           V output(BiEntry<K, V> entry) {
             return entry.value;
           }
@@ -683,17 +713,20 @@ class InverseEntry extends AbstractMapEntry<V, K> {
           }
 
           @Override
+          @ParametricNullness
           public V getKey() {
             return delegate.value;
           }
 
           @Override
+          @ParametricNullness
           public K getValue() {
             return delegate.key;
           }
 
           @Override
-          public K setValue(K key) {
+          @ParametricNullness
+          public K setValue(@ParametricNullness K key) {
             K oldKey = delegate.key;
             int keyHash = smearedHash(key);
             if (keyHash == delegate.keyHash && Objects.equal(key, oldKey)) {
@@ -733,7 +766,9 @@ Object writeReplace() {
     }
   }
 
-  private static final class InverseSerializedForm<K, V> implements Serializable {
+  private static final class InverseSerializedForm<
+          K extends @Nullable Object, V extends @Nullable Object>
+      implements Serializable {
     private final HashBiMap<K, V> bimap;
 
     InverseSerializedForm(HashBiMap<K, V> bimap) {
diff --git a/guava/src/com/google/common/collect/HashMultimap.java b/guava/src/com/google/common/collect/HashMultimap.java
index ba53318f8530..0aac491bf1d3 100644
--- a/guava/src/com/google/common/collect/HashMultimap.java
+++ b/guava/src/com/google/common/collect/HashMultimap.java
@@ -44,12 +44,17 @@
  * concurrent update operations, wrap your multimap with a call to {@link
  * Multimaps#synchronizedSetMultimap}.
  *
+ * <p><b>Warning:</b> Do not modify either a key <i>or a value</i> of a {@code HashMultimap} in a
+ * way that affects its {@link Object#equals} behavior. Undefined behavior and bugs will result.
+ *
  * @author Jared Levy
  * @since 2.0
  */
 @AnnotatedFor({"nullness"})
 @GwtCompatible(serializable = true, emulated = true)
-public final class HashMultimap<K, V> extends HashMultimapGwtSerializationDependencies<K, V> {
+@ElementTypesAreNonnullByDefault
+public final class HashMultimap<K extends @Nullable Object, V extends @Nullable Object>
+    extends HashMultimapGwtSerializationDependencies<K, V> {
   private static final int DEFAULT_VALUES_PER_KEY = 2;
 
   @VisibleForTesting transient int expectedValuesPerKey = DEFAULT_VALUES_PER_KEY;
@@ -60,7 +65,8 @@ public final class HashMultimap<K, V> extends HashMultimapGwtSerializationDepend
    * <p>This method will soon be deprecated in favor of {@code
    * MultimapBuilder.hashKeys().hashSetValues().build()}.
    */
-  public static <K, V> HashMultimap<K, V> create() {
+  public static <K extends @Nullable Object, V extends @Nullable Object>
+      HashMultimap<K, V> create() {
     return new HashMultimap<>();
   }
 
@@ -76,7 +82,8 @@ public static <K, V> HashMultimap<K, V> create() {
    * @throws IllegalArgumentException if {@code expectedKeys} or {@code expectedValuesPerKey} is
    *     negative
    */
-  public static <K, V> HashMultimap<K, V> create(int expectedKeys, int expectedValuesPerKey) {
+  public static <K extends @Nullable Object, V extends @Nullable Object> HashMultimap<K, V> create(
+      int expectedKeys, int expectedValuesPerKey) {
     return new HashMultimap<>(expectedKeys, expectedValuesPerKey);
   }
 
@@ -90,7 +97,8 @@ public static <K, V> HashMultimap<K, V> create(int expectedKeys, int expectedVal
    *
    * @param multimap the multimap whose contents are copied to this multimap
    */
-  public static <K, V> HashMultimap<K, V> create(Multimap<? extends K, ? extends V> multimap) {
+  public static <K extends @Nullable Object, V extends @Nullable Object> HashMultimap<K, V> create(
+      Multimap<? extends K, ? extends V> multimap) {
     return new HashMultimap<>(multimap);
   }
 
diff --git a/guava/src/com/google/common/collect/HashMultiset.java b/guava/src/com/google/common/collect/HashMultiset.java
index 95c386827554..13bf36977824 100644
--- a/guava/src/com/google/common/collect/HashMultiset.java
+++ b/guava/src/com/google/common/collect/HashMultiset.java
@@ -34,10 +34,11 @@
  */
 @AnnotatedFor({"nullness"})
 @GwtCompatible(serializable = true, emulated = true)
-public final class HashMultiset<E> extends AbstractMapBasedMultiset<E> {
+@ElementTypesAreNonnullByDefault
+public final class HashMultiset<E extends @Nullable Object> extends AbstractMapBasedMultiset<E> {
 
   /** Creates a new, empty {@code HashMultiset} using the default initial capacity. */
-  public static <E> HashMultiset<E> create() {
+  public static <E extends @Nullable Object> HashMultiset<E> create() {
     return new HashMultiset<E>();
   }
 
@@ -48,7 +49,7 @@ public static <E> HashMultiset<E> create() {
    * @param distinctElements the expected number of distinct elements
    * @throws IllegalArgumentException if {@code distinctElements} is negative
    */
-  public static <E> HashMultiset<E> create(int distinctElements) {
+  public static <E extends @Nullable Object> HashMultiset<E> create(int distinctElements) {
     return new HashMultiset<E>(distinctElements);
   }
 
@@ -59,7 +60,8 @@ public static <E> HashMultiset<E> create(int distinctElements) {
    *
    * @param elements the elements that the multiset should contain
    */
-  public static <E> HashMultiset<E> create(Iterable<? extends E> elements) {
+  public static <E extends @Nullable Object> HashMultiset<E> create(
+      Iterable<? extends E> elements) {
     HashMultiset<E> multiset = create(Multisets.inferDistinctElements(elements));
     Iterables.addAll(multiset, elements);
     return multiset;
diff --git a/guava/src/com/google/common/collect/Hashing.java b/guava/src/com/google/common/collect/Hashing.java
index fec4a41c9fc1..7421b40ba0b4 100644
--- a/guava/src/com/google/common/collect/Hashing.java
+++ b/guava/src/com/google/common/collect/Hashing.java
@@ -18,6 +18,7 @@
 
 import com.google.common.annotations.GwtCompatible;
 import com.google.common.primitives.Ints;
+import javax.annotation.CheckForNull;
 import org.checkerframework.checker.nullness.qual.Nullable;
 import org.checkerframework.dataflow.qual.Pure;
 import org.checkerframework.framework.qual.AnnotatedFor;
@@ -31,6 +32,7 @@
  */
 @AnnotatedFor({"nullness"})
 @GwtCompatible
+@ElementTypesAreNonnullByDefault
 final class Hashing {
   private Hashing() {}
 
@@ -54,7 +56,7 @@ static int smear(int hashCode) {
     return (int) (C2 * Integer.rotateLeft((int) (hashCode * C1), 15));
   }
 
-  static int smearedHash(@Nullable Object o) {
+  static int smearedHash(@CheckForNull Object o) {
     return smear((o == null) ? 0 : o.hashCode());
   }
 
diff --git a/guava/src/com/google/common/collect/ImmutableAsList.java b/guava/src/com/google/common/collect/ImmutableAsList.java
index 528a8dca1f85..c39747931796 100644
--- a/guava/src/com/google/common/collect/ImmutableAsList.java
+++ b/guava/src/com/google/common/collect/ImmutableAsList.java
@@ -21,6 +21,7 @@
 import java.io.InvalidObjectException;
 import java.io.ObjectInputStream;
 import java.io.Serializable;
+import javax.annotation.CheckForNull;
 
 /**
  * List returned by {@link ImmutableCollection#asList} that delegates {@code contains} checks to the
@@ -31,11 +32,12 @@
  */
 @GwtCompatible(serializable = true, emulated = true)
 @SuppressWarnings("serial")
+@ElementTypesAreNonnullByDefault
 abstract class ImmutableAsList<E> extends ImmutableList<E> {
   abstract ImmutableCollection<E> delegateCollection();
 
   @Override
-  public boolean contains(Object target) {
+  public boolean contains(@CheckForNull Object target) {
     // The collection's contains() is at least as fast as ImmutableList's
     // and is often faster.
     return delegateCollection().contains(target);
diff --git a/guava/src/com/google/common/collect/ImmutableBiMap.java b/guava/src/com/google/common/collect/ImmutableBiMap.java
index 76ae1ad35064..6bf472c586c2 100644
--- a/guava/src/com/google/common/collect/ImmutableBiMap.java
+++ b/guava/src/com/google/common/collect/ImmutableBiMap.java
@@ -18,6 +18,7 @@
 
 import static com.google.common.base.Preconditions.checkState;
 import static com.google.common.collect.CollectPreconditions.checkNonnegative;
+import static java.util.Objects.requireNonNull;
 
 import com.google.common.annotations.Beta;
 import com.google.common.annotations.GwtCompatible;
@@ -30,7 +31,8 @@
 import java.util.function.Function;
 import java.util.stream.Collector;
 import java.util.stream.Collectors;
-import javax.annotation.Nullable;
+import javax.annotation.CheckForNull;
+import org.checkerframework.checker.nullness.qual.Nullable;
 import org.checkerframework.dataflow.qual.SideEffectFree;
 import org.checkerframework.framework.qual.AnnotatedFor;
 
@@ -43,6 +45,7 @@
  */
 @AnnotatedFor({"nullness"})
 @GwtCompatible(serializable = true, emulated = true)
+@ElementTypesAreNonnullByDefault
 public abstract class ImmutableBiMap<K, V> extends ImmutableBiMapFauxverideShim<K, V>
     implements BiMap<K, V> {
 
@@ -58,13 +61,18 @@ public abstract class ImmutableBiMap<K, V> extends ImmutableBiMapFauxverideShim<
    *
    * @since 21.0
    */
-  public static <T, K, V> Collector<T, ?, ImmutableBiMap<K, V>> toImmutableBiMap(
-      Function<? super T, ? extends K> keyFunction,
-      Function<? super T, ? extends V> valueFunction) {
+  public static <T extends @Nullable Object, K, V>
+      Collector<T, ?, ImmutableBiMap<K, V>> toImmutableBiMap(
+          Function<? super T, ? extends K> keyFunction,
+          Function<? super T, ? extends V> valueFunction) {
     return CollectCollectors.toImmutableBiMap(keyFunction, valueFunction);
   }
 
-  /** Returns the empty bimap. */
+  /**
+   * Returns the empty bimap.
+   *
+   * <p><b>Performance note:</b> the instance returned is a singleton.
+   */
   // Casting to any type is safe because the set will never hold any elements.
   @SuppressWarnings("unchecked")
   public static <K, V> ImmutableBiMap<K, V> of() {
@@ -115,7 +123,165 @@ public static <K, V> ImmutableBiMap<K, V> of(
         entryOf(k1, v1), entryOf(k2, v2), entryOf(k3, v3), entryOf(k4, v4), entryOf(k5, v5));
   }
 
-  // looking for of() with > 5 entries? Use the builder instead.
+  /**
+   * Returns an immutable map containing the given entries, in order.
+   *
+   * @throws IllegalArgumentException if duplicate keys or values are added
+   * @since 31.0
+   */
+  public static <K, V> ImmutableBiMap<K, V> of(
+      K k1, V v1, K k2, V v2, K k3, V v3, K k4, V v4, K k5, V v5, K k6, V v6) {
+    return RegularImmutableBiMap.fromEntries(
+        entryOf(k1, v1),
+        entryOf(k2, v2),
+        entryOf(k3, v3),
+        entryOf(k4, v4),
+        entryOf(k5, v5),
+        entryOf(k6, v6));
+  }
+
+  /**
+   * Returns an immutable map containing the given entries, in order.
+   *
+   * @throws IllegalArgumentException if duplicate keys or values are added
+   * @since 31.0
+   */
+  public static <K, V> ImmutableBiMap<K, V> of(
+      K k1, V v1, K k2, V v2, K k3, V v3, K k4, V v4, K k5, V v5, K k6, V v6, K k7, V v7) {
+    return RegularImmutableBiMap.fromEntries(
+        entryOf(k1, v1),
+        entryOf(k2, v2),
+        entryOf(k3, v3),
+        entryOf(k4, v4),
+        entryOf(k5, v5),
+        entryOf(k6, v6),
+        entryOf(k7, v7));
+  }
+
+  /**
+   * Returns an immutable map containing the given entries, in order.
+   *
+   * @throws IllegalArgumentException if duplicate keys or values are added
+   * @since 31.0
+   */
+  public static <K, V> ImmutableBiMap<K, V> of(
+      K k1,
+      V v1,
+      K k2,
+      V v2,
+      K k3,
+      V v3,
+      K k4,
+      V v4,
+      K k5,
+      V v5,
+      K k6,
+      V v6,
+      K k7,
+      V v7,
+      K k8,
+      V v8) {
+    return RegularImmutableBiMap.fromEntries(
+        entryOf(k1, v1),
+        entryOf(k2, v2),
+        entryOf(k3, v3),
+        entryOf(k4, v4),
+        entryOf(k5, v5),
+        entryOf(k6, v6),
+        entryOf(k7, v7),
+        entryOf(k8, v8));
+  }
+
+  /**
+   * Returns an immutable map containing the given entries, in order.
+   *
+   * @throws IllegalArgumentException if duplicate keys or values are added
+   * @since 31.0
+   */
+  public static <K, V> ImmutableBiMap<K, V> of(
+      K k1,
+      V v1,
+      K k2,
+      V v2,
+      K k3,
+      V v3,
+      K k4,
+      V v4,
+      K k5,
+      V v5,
+      K k6,
+      V v6,
+      K k7,
+      V v7,
+      K k8,
+      V v8,
+      K k9,
+      V v9) {
+    return RegularImmutableBiMap.fromEntries(
+        entryOf(k1, v1),
+        entryOf(k2, v2),
+        entryOf(k3, v3),
+        entryOf(k4, v4),
+        entryOf(k5, v5),
+        entryOf(k6, v6),
+        entryOf(k7, v7),
+        entryOf(k8, v8),
+        entryOf(k9, v9));
+  }
+  /**
+   * Returns an immutable map containing the given entries, in order.
+   *
+   * @throws IllegalArgumentException if duplicate keys or values are added
+   * @since 31.0
+   */
+  public static <K, V> ImmutableBiMap<K, V> of(
+      K k1,
+      V v1,
+      K k2,
+      V v2,
+      K k3,
+      V v3,
+      K k4,
+      V v4,
+      K k5,
+      V v5,
+      K k6,
+      V v6,
+      K k7,
+      V v7,
+      K k8,
+      V v8,
+      K k9,
+      V v9,
+      K k10,
+      V v10) {
+    return RegularImmutableBiMap.fromEntries(
+        entryOf(k1, v1),
+        entryOf(k2, v2),
+        entryOf(k3, v3),
+        entryOf(k4, v4),
+        entryOf(k5, v5),
+        entryOf(k6, v6),
+        entryOf(k7, v7),
+        entryOf(k8, v8),
+        entryOf(k9, v9),
+        entryOf(k10, v10));
+  }
+
+  // looking for of() with > 10 entries? Use the builder or ofEntries instead.
+
+  /**
+   * Returns an immutable map containing the given entries, in order.
+   *
+   * @throws IllegalArgumentException if duplicate keys or values are provided
+   * @since 31.0
+   */
+  @SafeVarargs
+  public static <K, V> ImmutableBiMap<K, V> ofEntries(Entry<? extends K, ? extends V>... entries) {
+    @SuppressWarnings("unchecked") // we will only ever read these
+    Entry<K, V>[] entries2 = (Entry<K, V>[]) entries;
+    return RegularImmutableBiMap.fromEntries(entries2);
+  }
 
   /**
    * Returns a new builder. The generated builder is equivalent to the builder created by the {@link
@@ -153,7 +319,7 @@ public static <K, V> Builder<K, V> builderWithExpectedSize(int expectedSize) {
    *         .put("one", 1)
    *         .put("two", 2)
    *         .put("three", 3)
-   *         .build();
+   *         .buildOrThrow();
    * }</pre>
    *
    * <p>For <i>small</i> immutable bimaps, the {@code ImmutableBiMap.of()} methods are even more
@@ -166,8 +332,8 @@ public static <K, V> Builder<K, V> builderWithExpectedSize(int expectedSize) {
    * want a different order, consider using {@link #orderEntriesByValue(Comparator)}, which changes
    * this builder to sort entries by value.
    *
-   * <p>Builder instances can be reused - it is safe to call {@link #build} multiple times to build
-   * multiple bimaps in series. Each bimap is a superset of the bimaps created before it.
+   * <p>Builder instances can be reused - it is safe to call {@link #buildOrThrow} multiple times to
+   * build multiple bimaps in series. Each bimap is a superset of the bimaps created before it.
    *
    * @since 2.0
    */
@@ -265,15 +431,35 @@ Builder<K, V> combine(ImmutableMap.Builder<K, V> builder) {
      * order in which entries were inserted into the builder, unless {@link #orderEntriesByValue}
      * was called, in which case entries are sorted by value.
      *
+     * <p>Prefer the equivalent method {@link #buildOrThrow()} to make it explicit that the method
+     * will throw an exception if there are duplicate keys or values. The {@code build()} method
+     * will soon be deprecated.
+     *
      * @throws IllegalArgumentException if duplicate keys or values were added
      */
     @Override
     public ImmutableBiMap<K, V> build() {
+      return buildOrThrow();
+    }
+
+    /**
+     * Returns a newly-created immutable bimap, or throws an exception if any key or value was added
+     * more than once. The iteration order of the returned bimap is the order in which entries were
+     * inserted into the builder, unless {@link #orderEntriesByValue} was called, in which case
+     * entries are sorted by value.
+     *
+     * @throws IllegalArgumentException if duplicate keys or values were added
+     * @since 31.0
+     */
+    @Override
+    public ImmutableBiMap<K, V> buildOrThrow() {
       switch (size) {
         case 0:
           return of();
         case 1:
-          return of(entries[0].getKey(), entries[0].getValue());
+          // requireNonNull is safe because the first `size` elements have been filled in.
+          Entry<K, V> onlyEntry = requireNonNull(entries[0]);
+          return of(onlyEntry.getKey(), onlyEntry.getValue());
         default:
           /*
            * If entries is full, or if hash flooding is detected, then this implementation may end
@@ -297,6 +483,21 @@ public ImmutableBiMap<K, V> build() {
       }
     }
 
+    /**
+     * Throws {@link UnsupportedOperationException}. This method is inherited from {@link
+     * ImmutableMap.Builder}, but it does not make sense for bimaps.
+     *
+     * @throws UnsupportedOperationException always
+     * @deprecated This method does not make sense for bimaps and should not be called.
+     * @since 31.1
+     */
+    @DoNotCall
+    @Deprecated
+    @Override
+    public ImmutableBiMap<K, V> buildKeepingLast() {
+      throw new UnsupportedOperationException("Not supported for bimaps");
+    }
+
     @Override
     @VisibleForTesting
     ImmutableBiMap<K, V> buildJdkBacked() {
@@ -307,7 +508,9 @@ ImmutableBiMap<K, V> buildJdkBacked() {
         case 0:
           return of();
         case 1:
-          return of(entries[0].getKey(), entries[0].getValue());
+          // requireNonNull is safe because the first `size` elements have been filled in.
+          Entry<K, V> onlyEntry = requireNonNull(entries[0]);
+          return of(onlyEntry.getKey(), onlyEntry.getValue());
         default:
           entriesUsed = true;
           return RegularImmutableBiMap.fromEntryArray(size, entries);
@@ -408,6 +611,7 @@ final ImmutableSet<V> createValues() {
   @Deprecated
   @Override
   @DoNotCall("Always throws UnsupportedOperationException")
+  @CheckForNull
   public final V forcePut(K key, V value) {
     throw new UnsupportedOperationException();
   }
diff --git a/guava/src/com/google/common/collect/ImmutableBiMapFauxverideShim.java b/guava/src/com/google/common/collect/ImmutableBiMapFauxverideShim.java
index dd787d5a57aa..2f1f25c82982 100644
--- a/guava/src/com/google/common/collect/ImmutableBiMapFauxverideShim.java
+++ b/guava/src/com/google/common/collect/ImmutableBiMapFauxverideShim.java
@@ -17,9 +17,11 @@
 package com.google.common.collect;
 
 import com.google.common.annotations.GwtIncompatible;
+import com.google.errorprone.annotations.DoNotCall;
 import java.util.function.BinaryOperator;
 import java.util.function.Function;
 import java.util.stream.Collector;
+import org.checkerframework.checker.nullness.qual.Nullable;
 
 /**
  * "Overrides" the {@link ImmutableMap} static methods that lack {@link ImmutableBiMap} equivalents
@@ -29,6 +31,7 @@
  * @author Louis Wasserman
  */
 @GwtIncompatible
+@ElementTypesAreNonnullByDefault
 abstract class ImmutableBiMapFauxverideShim<K, V> extends ImmutableMap<K, V> {
   /**
    * Not supported. Use {@link ImmutableBiMap#toImmutableBiMap} instead. This method exists only to
@@ -39,9 +42,11 @@ abstract class ImmutableBiMapFauxverideShim<K, V> extends ImmutableMap<K, V> {
    * @deprecated Use {@link ImmutableBiMap#toImmutableBiMap}.
    */
   @Deprecated
-  public static <T, K, V> Collector<T, ?, ImmutableMap<K, V>> toImmutableMap(
-      Function<? super T, ? extends K> keyFunction,
-      Function<? super T, ? extends V> valueFunction) {
+  @DoNotCall("Use toImmutableBiMap")
+  public static <T extends @Nullable Object, K, V>
+      Collector<T, ?, ImmutableMap<K, V>> toImmutableMap(
+          Function<? super T, ? extends K> keyFunction,
+          Function<? super T, ? extends V> valueFunction) {
     throw new UnsupportedOperationException();
   }
 
@@ -54,10 +59,12 @@ abstract class ImmutableBiMapFauxverideShim<K, V> extends ImmutableMap<K, V> {
    * @deprecated
    */
   @Deprecated
-  public static <T, K, V> Collector<T, ?, ImmutableMap<K, V>> toImmutableMap(
-      Function<? super T, ? extends K> keyFunction,
-      Function<? super T, ? extends V> valueFunction,
-      BinaryOperator<V> mergeFunction) {
+  @DoNotCall("Use toImmutableBiMap")
+  public static <T extends @Nullable Object, K, V>
+      Collector<T, ?, ImmutableMap<K, V>> toImmutableMap(
+          Function<? super T, ? extends K> keyFunction,
+          Function<? super T, ? extends V> valueFunction,
+          BinaryOperator<V> mergeFunction) {
     throw new UnsupportedOperationException();
   }
 }
diff --git a/guava/src/com/google/common/collect/ImmutableClassToInstanceMap.java b/guava/src/com/google/common/collect/ImmutableClassToInstanceMap.java
index eff1a978763a..7ca083704284 100644
--- a/guava/src/com/google/common/collect/ImmutableClassToInstanceMap.java
+++ b/guava/src/com/google/common/collect/ImmutableClassToInstanceMap.java
@@ -25,6 +25,7 @@
 import com.google.errorprone.annotations.Immutable;
 import java.io.Serializable;
 import java.util.Map;
+import javax.annotation.CheckForNull;
 import org.checkerframework.checker.nullness.qual.Nullable;
 import org.checkerframework.framework.qual.AnnotatedFor;
 
@@ -38,6 +39,7 @@
 @AnnotatedFor({"nullness"})
 @Immutable(containerOf = "B")
 @GwtIncompatible
+@ElementTypesAreNonnullByDefault
 public final class ImmutableClassToInstanceMap<B> extends ForwardingMap<Class<? extends B>, B>
     implements ClassToInstanceMap<B>, Serializable {
 
@@ -47,6 +49,8 @@ public final class ImmutableClassToInstanceMap<B> extends ForwardingMap<Class<?
   /**
    * Returns an empty {@code ImmutableClassToInstanceMap}.
    *
+   * <p><b>Performance note:</b> the instance returned is a singleton.
+   *
    * @since 19.0
    */
   @SuppressWarnings("unchecked")
@@ -61,7 +65,7 @@ public static <B> ImmutableClassToInstanceMap<B> of() {
    */
   public static <B, T extends B> ImmutableClassToInstanceMap<B> of(Class<T> type, T value) {
     ImmutableMap<Class<? extends B>, B> map = ImmutableMap.<Class<? extends B>, B>of(type, value);
-    return new ImmutableClassToInstanceMap<B>(map);
+    return new ImmutableClassToInstanceMap<>(map);
   }
 
   /**
@@ -69,7 +73,7 @@ public static <B, T extends B> ImmutableClassToInstanceMap<B> of(Class<T> type,
    * Builder} constructor.
    */
   public static <B> Builder<B> builder() {
-    return new Builder<B>();
+    return new Builder<>();
   }
 
   /**
@@ -130,11 +134,11 @@ private static <B, T extends B> T cast(Class<T> type, B value) {
      * @throws IllegalArgumentException if duplicate keys were added
      */
     public ImmutableClassToInstanceMap<B> build() {
-      ImmutableMap<Class<? extends B>, B> map = mapBuilder.build();
+      ImmutableMap<Class<? extends B>, B> map = mapBuilder.buildOrThrow();
       if (map.isEmpty()) {
         return of();
       } else {
-        return new ImmutableClassToInstanceMap<B>(map);
+        return new ImmutableClassToInstanceMap<>(map);
       }
     }
   }
@@ -173,7 +177,8 @@ protected Map<Class<? extends B>, B> delegate() {
 
   @Override
   @SuppressWarnings("unchecked") // value could not get in if not a T
-  public <T extends B> @Nullable T getInstance(Class<T> type) {
+  @CheckForNull
+  public <T extends B> T getInstance(Class<T> type) {
     return (T) delegate.get(checkNotNull(type));
   }
 
@@ -187,6 +192,7 @@ protected Map<Class<? extends B>, B> delegate() {
   @Deprecated
   @Override
   @DoNotCall("Always throws UnsupportedOperationException")
+  @CheckForNull
   public <T extends B> T putInstance(Class<T> type, T value) {
     throw new UnsupportedOperationException();
   }
diff --git a/guava/src/com/google/common/collect/ImmutableCollection.java b/guava/src/com/google/common/collect/ImmutableCollection.java
index 8085ce58cfd8..7261dca60387 100644
--- a/guava/src/com/google/common/collect/ImmutableCollection.java
+++ b/guava/src/com/google/common/collect/ImmutableCollection.java
@@ -32,6 +32,7 @@
 import java.util.Spliterator;
 import java.util.Spliterators;
 import java.util.function.Predicate;
+import javax.annotation.CheckForNull;
 import org.checkerframework.checker.nullness.qual.NonNull;
 import org.checkerframework.checker.nullness.qual.Nullable;
 import org.checkerframework.dataflow.qual.Pure;
@@ -158,7 +159,7 @@
  * <h3>See also</h3>
  *
  * <p>See the Guava User Guide article on <a href=
- * "https://github.com/google/guava/wiki/ImmutableCollectionsExplained"> immutable collections</a>.
+ * "https://github.com/google/guava/wiki/ImmutableCollectionsExplained">immutable collections</a>.
  *
  * @since 2.0
  */
@@ -166,6 +167,7 @@
 @DoNotMock("Use ImmutableList.of or another implementation")
 @GwtCompatible(emulated = true)
 @SuppressWarnings("serial") // we're overriding default serialization
+@ElementTypesAreNonnullByDefault
 // TODO(kevinb): I think we should push everything down to "BaseImmutableCollection" or something,
 // just to do everything we can to emphasize the "practically an interface" nature of this class.
 public abstract class ImmutableCollection<E extends @NonNull Object> extends AbstractCollection<E> implements Serializable {
@@ -197,7 +199,20 @@ public Spliterator<E> spliterator() {
 
   @CanIgnoreReturnValue
   @Override
-  public final <T> @Nullable T[] toArray(T[] other) {
+  /*
+   * This suppression is here for two reasons:
+   *
+   * 1. b/192354773 in our checker affects toArray declarations.
+   *
+   * 2. `other[size] = null` is unsound. We could "fix" this by requiring callers to pass in an
+   * array with a nullable element type. But probably they usually want an array with a non-nullable
+   * type. That said, we could *accept* a `@Nullable T[]` (which, given that we treat arrays as
+   * covariant, would still permit a plain `T[]`) and return a plain `T[]`. But of course that would
+   * require its own suppression, since it is also unsound. toArray(T[]) is just a mess from a
+   * nullness perspective. The signature below at least has the virtue of being relatively simple.
+   */
+  @SuppressWarnings("nullness")
+  public final <T extends @Nullable Object> T[] toArray(T[] other) {
     checkNotNull(other);
     int size = size();
 
@@ -215,7 +230,8 @@ public Spliterator<E> spliterator() {
   }
 
   /** If this collection is backed by an array of its elements in insertion order, returns it. */
-  Object @Nullable [] internalArray() {
+  @CheckForNull
+  Object[] internalArray() {
     return null;
   }
 
@@ -237,7 +253,7 @@ int internalArrayEnd() {
 
   @Pure
   @Override
-  public abstract boolean contains(@Nullable Object object);
+  public abstract boolean contains(@CheckForNull Object object);
 
   /**
    * Guaranteed to throw an exception and leave the collection unmodified.
@@ -263,7 +279,7 @@ public final boolean add(E e) {
   @Deprecated
   @Override
   @DoNotCall("Always throws UnsupportedOperationException")
-  public final boolean remove(@Nullable Object object) {
+  public final boolean remove(@CheckForNull Object object) {
     throw new UnsupportedOperationException();
   }
 
@@ -369,7 +385,7 @@ public ImmutableList<E> asList() {
    * offset. Returns {@code offset + size()}.
    */
   @CanIgnoreReturnValue
-  int copyIntoArray(Object[] dst, int offset) {
+  int copyIntoArray(@Nullable Object[] dst, int offset) {
     for (E e : this) {
       dst[offset++] = e;
     }
diff --git a/guava/src/com/google/common/collect/ImmutableEntry.java b/guava/src/com/google/common/collect/ImmutableEntry.java
index 3bae7e761ea2..8be1a54b4280 100644
--- a/guava/src/com/google/common/collect/ImmutableEntry.java
+++ b/guava/src/com/google/common/collect/ImmutableEntry.java
@@ -25,29 +25,34 @@
 /** @see com.google.common.collect.Maps#immutableEntry(Object, Object) */
 @AnnotatedFor({"nullness"})
 @GwtCompatible(serializable = true)
-class ImmutableEntry<K, V> extends AbstractMapEntry<K, V> implements Serializable {
-  final @Nullable K key;
-  final @Nullable V value;
+@ElementTypesAreNonnullByDefault
+class ImmutableEntry<K extends @Nullable Object, V extends @Nullable Object>
+    extends AbstractMapEntry<K, V> implements Serializable {
+  @ParametricNullness final K key;
+  @ParametricNullness final V value;
 
-  ImmutableEntry(@Nullable K key, @Nullable V value) {
+  ImmutableEntry(@ParametricNullness K key, @ParametricNullness V value) {
     this.key = key;
     this.value = value;
   }
 
   @Pure
   @Override
-  public final @Nullable K getKey() {
+  @ParametricNullness
+  public final K getKey() {
     return key;
   }
 
   @Pure
   @Override
-  public final @Nullable V getValue() {
+  @ParametricNullness
+  public final V getValue() {
     return value;
   }
 
   @Override
-  public final V setValue(V value) {
+  @ParametricNullness
+  public final V setValue(@ParametricNullness V value) {
     throw new UnsupportedOperationException();
   }
 
diff --git a/guava/src/com/google/common/collect/ImmutableEnumMap.java b/guava/src/com/google/common/collect/ImmutableEnumMap.java
index f12e1a9e686c..d1e10f97d0b9 100644
--- a/guava/src/com/google/common/collect/ImmutableEnumMap.java
+++ b/guava/src/com/google/common/collect/ImmutableEnumMap.java
@@ -24,7 +24,7 @@
 import java.util.EnumMap;
 import java.util.Spliterator;
 import java.util.function.BiConsumer;
-import org.checkerframework.checker.nullness.qual.Nullable;
+import javax.annotation.CheckForNull;
 
 /**
  * Implementation of {@link ImmutableMap} backed by a non-empty {@link java.util.EnumMap}.
@@ -33,6 +33,7 @@
  */
 @GwtCompatible(serializable = true, emulated = true)
 @SuppressWarnings("serial") // we're overriding default serialization
+@ElementTypesAreNonnullByDefault
 final class ImmutableEnumMap<K extends Enum<K>, V> extends IteratorBasedImmutableMap<K, V> {
   static <K extends Enum<K>, V> ImmutableMap<K, V> asImmutable(EnumMap<K, V> map) {
     switch (map.size()) {
@@ -69,17 +70,18 @@ public int size() {
   }
 
   @Override
-  public boolean containsKey(@Nullable Object key) {
+  public boolean containsKey(@CheckForNull Object key) {
     return delegate.containsKey(key);
   }
 
   @Override
-  public V get(Object key) {
+  @CheckForNull
+  public V get(@CheckForNull Object key) {
     return delegate.get(key);
   }
 
   @Override
-  public boolean equals(Object object) {
+  public boolean equals(@CheckForNull Object object) {
     if (object == this) {
       return true;
     }
diff --git a/guava/src/com/google/common/collect/ImmutableEnumSet.java b/guava/src/com/google/common/collect/ImmutableEnumSet.java
index 55ba01a11cd0..aefeba2b619f 100644
--- a/guava/src/com/google/common/collect/ImmutableEnumSet.java
+++ b/guava/src/com/google/common/collect/ImmutableEnumSet.java
@@ -23,6 +23,7 @@
 import java.util.EnumSet;
 import java.util.Spliterator;
 import java.util.function.Consumer;
+import javax.annotation.CheckForNull;
 import org.checkerframework.checker.nullness.qual.Nullable;
 import org.checkerframework.dataflow.qual.Pure;
 import org.checkerframework.framework.qual.AnnotatedFor;
@@ -35,6 +36,7 @@
 @AnnotatedFor({"nullness"})
 @GwtCompatible(serializable = true, emulated = true)
 @SuppressWarnings("serial") // we're overriding default serialization
+@ElementTypesAreNonnullByDefault
 final class ImmutableEnumSet<E extends Enum<E>> extends ImmutableSet<E> {
   @SuppressWarnings("rawtypes") // necessary to compile against Java 8
   static ImmutableSet asImmutable(EnumSet set) {
@@ -90,7 +92,7 @@ public int size() {
 
   @Pure
   @Override
-  public boolean contains(@Nullable Object object) {
+  public boolean contains(@CheckForNull Object object) {
     return delegate.contains(object);
   }
 
@@ -111,7 +113,7 @@ public boolean isEmpty() {
 
   @Pure
   @Override
-  public boolean equals(@Nullable Object object) {
+  public boolean equals(@CheckForNull Object object) {
     if (object == this) {
       return true;
     }
diff --git a/guava/src/com/google/common/collect/ImmutableList.java b/guava/src/com/google/common/collect/ImmutableList.java
index f039d12ab2a2..58f15602dd67 100644
--- a/guava/src/com/google/common/collect/ImmutableList.java
+++ b/guava/src/com/google/common/collect/ImmutableList.java
@@ -23,12 +23,14 @@
 import static com.google.common.collect.CollectPreconditions.checkNonnegative;
 import static com.google.common.collect.ObjectArrays.checkElementsNotNull;
 import static com.google.common.collect.RegularImmutableList.EMPTY;
+import static java.util.Objects.requireNonNull;
 
 import com.google.common.annotations.Beta;
 import com.google.common.annotations.GwtCompatible;
 import com.google.common.annotations.VisibleForTesting;
 import com.google.errorprone.annotations.CanIgnoreReturnValue;
 import com.google.errorprone.annotations.DoNotCall;
+import com.google.errorprone.annotations.InlineMe;
 import java.io.InvalidObjectException;
 import java.io.ObjectInputStream;
 import java.io.Serializable;
@@ -43,6 +45,7 @@
 import java.util.function.Consumer;
 import java.util.function.UnaryOperator;
 import java.util.stream.Collector;
+import javax.annotation.CheckForNull;
 import org.checkerframework.checker.nullness.qual.NonNull;
 import org.checkerframework.checker.nullness.qual.Nullable;
 import org.checkerframework.dataflow.qual.Pure;
@@ -53,7 +56,7 @@
  * {@link ImmutableCollection}.
  *
  * <p>See the Guava User Guide article on <a href=
- * "https://github.com/google/guava/wiki/ImmutableCollectionsExplained"> immutable collections</a>.
+ * "https://github.com/google/guava/wiki/ImmutableCollectionsExplained">immutable collections</a>.
  *
  * @see ImmutableMap
  * @see ImmutableSet
@@ -63,7 +66,8 @@
 @AnnotatedFor({"nullness"})
 @GwtCompatible(serializable = true, emulated = true)
 @SuppressWarnings("serial") // we're overriding default serialization
-public abstract class ImmutableList<E extends @NonNull Object> extends ImmutableCollection<E>
+@ElementTypesAreNonnullByDefault
+public abstract class ImmutableList<E> extends ImmutableCollection<E>
     implements List<E>, RandomAccess {
 
   /**
@@ -80,6 +84,8 @@ public abstract class ImmutableList<E extends @NonNull Object> extends Immutable
    * Returns the empty immutable list. This list behaves and performs comparably to {@link
    * Collections#emptyList}, and is preferable mainly for consistency and maintainability of your
    * code.
+   *
+   * <p><b>Performance note:</b> the instance returned is a singleton.
    */
   // Casting to any type is safe because the list will never hold any elements.
   @SuppressWarnings("unchecked")
@@ -371,17 +377,27 @@ static <E> ImmutableList<E> asImmutableList(Object[] elements) {
    * Views the array as an immutable list. Copies if the specified range does not cover the complete
    * array. Does not check for nulls.
    */
-  static <E> ImmutableList<E> asImmutableList(Object[] elements, int length) {
+  static <E> ImmutableList<E> asImmutableList(@Nullable Object[] elements, int length) {
     switch (length) {
       case 0:
         return of();
       case 1:
-        return of((E) elements[0]);
+        /*
+         * requireNonNull is safe because the callers promise to put non-null objects in the first
+         * `length` array elements.
+         */
+        @SuppressWarnings("unchecked") // our callers put only E instances into the array
+        E onlyElement = (E) requireNonNull(elements[0]);
+        return of(onlyElement);
       default:
-        if (length < elements.length) {
-          elements = Arrays.copyOf(elements, length);
-        }
-        return new RegularImmutableList<E>(elements);
+        /*
+         * The suppression is safe because the callers promise to put non-null objects in the first
+         * `length` array elements.
+         */
+        @SuppressWarnings("nullness")
+        Object[] elementsWithoutTrailingNulls =
+            length < elements.length ? Arrays.copyOf(elements, length) : elements;
+        return new RegularImmutableList<E>(elementsWithoutTrailingNulls);
     }
   }
 
@@ -420,18 +436,18 @@ public void forEach(Consumer<? super E> consumer) {
   }
 
   @Override
-  public int indexOf(@Nullable Object object) {
+  public int indexOf(@CheckForNull Object object) {
     return (object == null) ? -1 : Lists.indexOfImpl(this, object);
   }
 
   @Pure
   @Override
-  public int lastIndexOf(@Nullable Object object) {
+  public int lastIndexOf(@CheckForNull Object object) {
     return (object == null) ? -1 : Lists.lastIndexOfImpl(this, object);
   }
 
   @Override
-  public boolean contains(@Nullable Object object) {
+  public boolean contains(@CheckForNull Object object) {
     return indexOf(object) >= 0;
   }
 
@@ -582,19 +598,23 @@ public final void sort(Comparator<? super E> c) {
    * Returns this list instance.
    *
    * @since 2.0
+   * @deprecated There is no reason to use this; it always returns {@code this}.
    */
+  @InlineMe(replacement = "this")
+  @Deprecated
   @Override
   public final ImmutableList<E> asList() {
     return this;
   }
 
   @Override
+  @SuppressWarnings("value:methodref.param")
   public Spliterator<E> spliterator() {
     return CollectSpliterators.indexed(size(), SPLITERATOR_CHARACTERISTICS, this::get);
   }
 
   @Override
-  int copyIntoArray(Object[] dst, int offset) {
+  int copyIntoArray(@Nullable Object[] dst, int offset) {
     // this loop is faster for RandomAccess instances, which ImmutableLists are
     int size = size();
     for (int i = 0; i < size; i++) {
@@ -635,18 +655,18 @@ public ImmutableList<E> reverse() {
     }
 
     @Override
-    public boolean contains(@Nullable Object object) {
+    public boolean contains(@CheckForNull Object object) {
       return forwardList.contains(object);
     }
 
     @Override
-    public int indexOf(@Nullable Object object) {
+    public int indexOf(@CheckForNull Object object) {
       int index = forwardList.lastIndexOf(object);
       return (index >= 0) ? reverseIndex(index) : -1;
     }
 
     @Override
-    public int lastIndexOf(@Nullable Object object) {
+    public int lastIndexOf(@CheckForNull Object object) {
       int index = forwardList.indexOf(object);
       return (index >= 0) ? reverseIndex(index) : -1;
     }
@@ -675,7 +695,7 @@ boolean isPartialView() {
   }
 
   @Override
-  public boolean equals(@Nullable Object obj) {
+  public boolean equals(@CheckForNull Object obj) {
     return Lists.equalsImpl(this, obj);
   }
 
@@ -766,7 +786,8 @@ public static <E> Builder<E> builderWithExpectedSize(int expectedSize) {
    * @since 2.0
    */
   public static final class Builder<E> extends ImmutableCollection.Builder<E> {
-    @VisibleForTesting Object[] contents;
+    // The first `size` elements are non-null.
+    @VisibleForTesting @Nullable Object[] contents;
     private int size;
     private boolean forceCopy;
 
@@ -779,7 +800,7 @@ public Builder() {
     }
 
     Builder(int capacity) {
-      this.contents = new Object[capacity];
+      this.contents = new @Nullable Object[capacity];
       this.size = 0;
     }
 
@@ -824,8 +845,16 @@ public Builder<E> add(E... elements) {
       return this;
     }
 
-    private void add(Object[] elements, int n) {
+    private void add(@Nullable Object[] elements, int n) {
       getReadyToExpandTo(size + n);
+      /*
+       * The following call is not statically checked, since arraycopy accepts plain Object for its
+       * parameters. If it were statically checked, the checker would still be OK with it, since
+       * we're copying into a `contents` array whose type allows it to contain nulls. Still, it's
+       * worth noting that we promise not to put nulls into the array in the first `size` elements.
+       * We uphold that promise here because our callers promise that `elements` will not contain
+       * nulls in its first `n` elements.
+       */
       System.arraycopy(elements, 0, contents, size, n);
       size += n;
     }
diff --git a/guava/src/com/google/common/collect/ImmutableListMultimap.java b/guava/src/com/google/common/collect/ImmutableListMultimap.java
index d0906828921d..8db385eec27f 100644
--- a/guava/src/com/google/common/collect/ImmutableListMultimap.java
+++ b/guava/src/com/google/common/collect/ImmutableListMultimap.java
@@ -35,6 +35,7 @@
 import java.util.function.Function;
 import java.util.stream.Collector;
 import java.util.stream.Stream;
+import javax.annotation.CheckForNull;
 import org.checkerframework.checker.nullness.qual.Nullable;
 import org.checkerframework.framework.qual.AnnotatedFor;
 
@@ -43,13 +44,14 @@
  * detailed at {@link ImmutableCollection}.
  *
  * <p>See the Guava User Guide article on <a href=
- * "https://github.com/google/guava/wiki/ImmutableCollectionsExplained"> immutable collections</a>.
+ * "https://github.com/google/guava/wiki/ImmutableCollectionsExplained">immutable collections</a>.
  *
  * @author Jared Levy
  * @since 2.0
  */
 @AnnotatedFor({"nullness"})
 @GwtCompatible(serializable = true, emulated = true)
+@ElementTypesAreNonnullByDefault
 public class ImmutableListMultimap<K, V> extends ImmutableMultimap<K, V>
     implements ListMultimap<K, V> {
   /**
@@ -80,9 +82,10 @@ public class ImmutableListMultimap<K, V> extends ImmutableMultimap<K, V>
    *
    * @since 21.0
    */
-  public static <T, K, V> Collector<T, ?, ImmutableListMultimap<K, V>> toImmutableListMultimap(
-      Function<? super T, ? extends K> keyFunction,
-      Function<? super T, ? extends V> valueFunction) {
+  public static <T extends @Nullable Object, K, V>
+      Collector<T, ?, ImmutableListMultimap<K, V>> toImmutableListMultimap(
+          Function<? super T, ? extends K> keyFunction,
+          Function<? super T, ? extends V> valueFunction) {
     return CollectCollectors.toImmutableListMultimap(keyFunction, valueFunction);
   }
 
@@ -117,14 +120,18 @@ public class ImmutableListMultimap<K, V> extends ImmutableMultimap<K, V>
    *
    * @since 21.0
    */
-  public static <T, K, V>
+  public static <T extends @Nullable Object, K, V>
       Collector<T, ?, ImmutableListMultimap<K, V>> flatteningToImmutableListMultimap(
           Function<? super T, ? extends K> keyFunction,
           Function<? super T, ? extends Stream<? extends V>> valuesFunction) {
     return CollectCollectors.flatteningToImmutableListMultimap(keyFunction, valuesFunction);
   }
 
-  /** Returns the empty multimap. */
+  /**
+   * Returns the empty multimap.
+   *
+   * <p><b>Performance note:</b> the instance returned is a singleton.
+   */
   // Casting is safe because the multimap will never hold any elements.
   @SuppressWarnings("unchecked")
   public static <K, V> ImmutableListMultimap<K, V> of() {
@@ -372,7 +379,7 @@ static <K, V> ImmutableListMultimap<K, V> fromMapEntries(
       }
     }
 
-    return new ImmutableListMultimap<>(builder.build(), size);
+    return new ImmutableListMultimap<>(builder.buildOrThrow(), size);
   }
 
   ImmutableListMultimap(ImmutableMap<K, ImmutableList<V>> map, int size) {
@@ -387,13 +394,13 @@ static <K, V> ImmutableListMultimap<K, V> fromMapEntries(
    * parameters used to build this multimap.
    */
   @Override
-  public ImmutableList<V> get(@Nullable K key) {
+  public ImmutableList<V> get(K key) {
     // This cast is safe as its type is known in constructor.
     @Nullable ImmutableList<V> list = (@Nullable ImmutableList<V>) map.get(key);
     return (list == null) ? ImmutableList.<V>of() : list;
   }
 
-  @LazyInit @RetainedWith private transient ImmutableListMultimap<V, K> inverse;
+  @LazyInit @RetainedWith @CheckForNull private transient ImmutableListMultimap<V, K> inverse;
 
   /**
    * {@inheritDoc}
@@ -430,7 +437,7 @@ private ImmutableListMultimap<V, K> invert() {
   @Deprecated
   @Override
   @DoNotCall("Always throws UnsupportedOperationException")
-  public final ImmutableList<V> removeAll(@Nullable Object key) {
+  public final ImmutableList<V> removeAll(@CheckForNull Object key) {
     throw new UnsupportedOperationException();
   }
 
@@ -485,7 +492,7 @@ private void readObject(ObjectInputStream stream) throws IOException, ClassNotFo
 
     ImmutableMap<Object, ImmutableList<Object>> tmpMap;
     try {
-      tmpMap = builder.build();
+      tmpMap = builder.buildOrThrow();
     } catch (IllegalArgumentException e) {
       throw (InvalidObjectException) new InvalidObjectException(e.getMessage()).initCause(e);
     }
diff --git a/guava/src/com/google/common/collect/ImmutableMap.java b/guava/src/com/google/common/collect/ImmutableMap.java
index 56479d35508f..6b192baa73dc 100644
--- a/guava/src/com/google/common/collect/ImmutableMap.java
+++ b/guava/src/com/google/common/collect/ImmutableMap.java
@@ -20,6 +20,7 @@
 import static com.google.common.base.Preconditions.checkState;
 import static com.google.common.collect.CollectPreconditions.checkEntryNotNull;
 import static com.google.common.collect.CollectPreconditions.checkNonnegative;
+import static java.util.Objects.requireNonNull;
 
 import com.google.common.annotations.Beta;
 import com.google.common.annotations.GwtCompatible;
@@ -31,14 +32,16 @@
 import com.google.j2objc.annotations.RetainedWith;
 import com.google.j2objc.annotations.WeakOuter;
 import java.io.Serializable;
-import java.util.AbstractMap;
 import java.util.Arrays;
+import java.util.BitSet;
 import java.util.Collection;
 import java.util.Collections;
 import java.util.Comparator;
 import java.util.EnumMap;
+import java.util.HashSet;
 import java.util.Iterator;
 import java.util.Map;
+import java.util.Set;
 import java.util.SortedMap;
 import java.util.Spliterator;
 import java.util.Spliterators;
@@ -47,6 +50,7 @@
 import java.util.function.Function;
 import java.util.stream.Collector;
 import java.util.stream.Collectors;
+import javax.annotation.CheckForNull;
 import org.checkerframework.checker.nullness.qual.MonotonicNonNull;
 import org.checkerframework.checker.nullness.qual.NonNull;
 import org.checkerframework.checker.nullness.qual.Nullable;
@@ -59,7 +63,7 @@
  * {@link ImmutableCollection}.
  *
  * <p>See the Guava User Guide article on <a href=
- * "https://github.com/google/guava/wiki/ImmutableCollectionsExplained"> immutable collections</a>.
+ * "https://github.com/google/guava/wiki/ImmutableCollectionsExplained">immutable collections</a>.
  *
  * @author Jesse Wilson
  * @author Kevin Bourrillion
@@ -69,8 +73,8 @@
 @DoNotMock("Use ImmutableMap.of or another implementation")
 @GwtCompatible(serializable = true, emulated = true)
 @SuppressWarnings("serial") // we're overriding default serialization
-public abstract class ImmutableMap<K extends @NonNull Object, V extends @NonNull Object>
-    implements Map<K, V>, Serializable {
+@ElementTypesAreNonnullByDefault
+public abstract class ImmutableMap<K, V> implements Map<K, V>, Serializable {
 
   /**
    * Returns a {@link Collector} that accumulates elements into an {@code ImmutableMap} whose keys
@@ -84,10 +88,10 @@ public abstract class ImmutableMap<K extends @NonNull Object, V extends @NonNull
    *
    * @since 21.0
    */
-  public static <T extends @NonNull Object, K extends @NonNull Object, V extends @NonNull Object>
-  Collector<T, ?, ImmutableMap<K, V>> toImmutableMap(
-      Function<? super T, ? extends K> keyFunction,
-      Function<? super T, ? extends V> valueFunction) {
+  public static <T extends @Nullable Object, K, V>
+      Collector<T, ?, ImmutableMap<K, V>> toImmutableMap(
+          Function<? super T, ? extends K> keyFunction,
+          Function<? super T, ? extends V> valueFunction) {
     return CollectCollectors.toImmutableMap(keyFunction, valueFunction);
   }
 
@@ -101,11 +105,11 @@ public abstract class ImmutableMap<K extends @NonNull Object, V extends @NonNull
    *
    * @since 21.0
    */
-  public static <T extends @NonNull Object, K extends @NonNull Object, V extends @NonNull Object>
-  Collector<T, ?, ImmutableMap<K, V>> toImmutableMap(
-      Function<? super T, ? extends K> keyFunction,
-      Function<? super T, ? extends V> valueFunction,
-      BinaryOperator<V> mergeFunction) {
+  public static <T extends @Nullable Object, K, V>
+      Collector<T, ?, ImmutableMap<K, V>> toImmutableMap(
+          Function<? super T, ? extends K> keyFunction,
+          Function<? super T, ? extends V> valueFunction,
+          BinaryOperator<V> mergeFunction) {
     return CollectCollectors.toImmutableMap(keyFunction, valueFunction, mergeFunction);
   }
 
@@ -113,6 +117,8 @@ public abstract class ImmutableMap<K extends @NonNull Object, V extends @NonNull
    * Returns the empty map. This map behaves and performs comparably to {@link
    * Collections#emptyMap}, and is preferable mainly for consistency and maintainability of your
    * code.
+   *
+   * <p><b>Performance note:</b> the instance returned is a singleton.
    */
   @SuppressWarnings("unchecked")
   public static <K, V> ImmutableMap<K, V> of() {
@@ -167,7 +173,166 @@ public static <K, V> ImmutableMap<K, V> of(
         entryOf(k1, v1), entryOf(k2, v2), entryOf(k3, v3), entryOf(k4, v4), entryOf(k5, v5));
   }
 
-  // looking for of() with > 5 entries? Use the builder instead.
+  /**
+   * Returns an immutable map containing the given entries, in order.
+   *
+   * @throws IllegalArgumentException if duplicate keys are provided
+   * @since 31.0
+   */
+  public static <K, V> ImmutableMap<K, V> of(
+      K k1, V v1, K k2, V v2, K k3, V v3, K k4, V v4, K k5, V v5, K k6, V v6) {
+    return RegularImmutableMap.fromEntries(
+        entryOf(k1, v1),
+        entryOf(k2, v2),
+        entryOf(k3, v3),
+        entryOf(k4, v4),
+        entryOf(k5, v5),
+        entryOf(k6, v6));
+  }
+
+  /**
+   * Returns an immutable map containing the given entries, in order.
+   *
+   * @throws IllegalArgumentException if duplicate keys are provided
+   * @since 31.0
+   */
+  public static <K, V> ImmutableMap<K, V> of(
+      K k1, V v1, K k2, V v2, K k3, V v3, K k4, V v4, K k5, V v5, K k6, V v6, K k7, V v7) {
+    return RegularImmutableMap.fromEntries(
+        entryOf(k1, v1),
+        entryOf(k2, v2),
+        entryOf(k3, v3),
+        entryOf(k4, v4),
+        entryOf(k5, v5),
+        entryOf(k6, v6),
+        entryOf(k7, v7));
+  }
+
+  /**
+   * Returns an immutable map containing the given entries, in order.
+   *
+   * @throws IllegalArgumentException if duplicate keys are provided
+   * @since 31.0
+   */
+  public static <K, V> ImmutableMap<K, V> of(
+      K k1,
+      V v1,
+      K k2,
+      V v2,
+      K k3,
+      V v3,
+      K k4,
+      V v4,
+      K k5,
+      V v5,
+      K k6,
+      V v6,
+      K k7,
+      V v7,
+      K k8,
+      V v8) {
+    return RegularImmutableMap.fromEntries(
+        entryOf(k1, v1),
+        entryOf(k2, v2),
+        entryOf(k3, v3),
+        entryOf(k4, v4),
+        entryOf(k5, v5),
+        entryOf(k6, v6),
+        entryOf(k7, v7),
+        entryOf(k8, v8));
+  }
+
+  /**
+   * Returns an immutable map containing the given entries, in order.
+   *
+   * @throws IllegalArgumentException if duplicate keys are provided
+   * @since 31.0
+   */
+  public static <K, V> ImmutableMap<K, V> of(
+      K k1,
+      V v1,
+      K k2,
+      V v2,
+      K k3,
+      V v3,
+      K k4,
+      V v4,
+      K k5,
+      V v5,
+      K k6,
+      V v6,
+      K k7,
+      V v7,
+      K k8,
+      V v8,
+      K k9,
+      V v9) {
+    return RegularImmutableMap.fromEntries(
+        entryOf(k1, v1),
+        entryOf(k2, v2),
+        entryOf(k3, v3),
+        entryOf(k4, v4),
+        entryOf(k5, v5),
+        entryOf(k6, v6),
+        entryOf(k7, v7),
+        entryOf(k8, v8),
+        entryOf(k9, v9));
+  }
+
+  /**
+   * Returns an immutable map containing the given entries, in order.
+   *
+   * @throws IllegalArgumentException if duplicate keys are provided
+   * @since 31.0
+   */
+  public static <K, V> ImmutableMap<K, V> of(
+      K k1,
+      V v1,
+      K k2,
+      V v2,
+      K k3,
+      V v3,
+      K k4,
+      V v4,
+      K k5,
+      V v5,
+      K k6,
+      V v6,
+      K k7,
+      V v7,
+      K k8,
+      V v8,
+      K k9,
+      V v9,
+      K k10,
+      V v10) {
+    return RegularImmutableMap.fromEntries(
+        entryOf(k1, v1),
+        entryOf(k2, v2),
+        entryOf(k3, v3),
+        entryOf(k4, v4),
+        entryOf(k5, v5),
+        entryOf(k6, v6),
+        entryOf(k7, v7),
+        entryOf(k8, v8),
+        entryOf(k9, v9),
+        entryOf(k10, v10));
+  }
+
+  // looking for of() with > 10 entries? Use the builder or ofEntries instead.
+
+  /**
+   * Returns an immutable map containing the given entries, in order.
+   *
+   * @throws IllegalArgumentException if duplicate keys are provided
+   * @since 31.0
+   */
+  @SafeVarargs
+  public static <K, V> ImmutableMap<K, V> ofEntries(Entry<? extends K, ? extends V>... entries) {
+    @SuppressWarnings("unchecked") // we will only ever read these
+    Entry<K, V>[] entries2 = (Entry<K, V>[]) entries;
+    return RegularImmutableMap.fromEntries(entries2);
+  }
 
   /**
    * Verifies that {@code key} and {@code value} are non-null, and returns a new immutable entry
@@ -177,8 +342,7 @@ public static <K, V> ImmutableMap<K, V> of(
    * UnsupportedOperationException}.
    */
   static <K, V> Entry<K, V> entryOf(K key, V value) {
-    checkEntryNotNull(key, value);
-    return new AbstractMap.SimpleImmutableEntry<>(key, value);
+    return new ImmutableMapEntry<>(key, value);
   }
 
   /**
@@ -208,7 +372,7 @@ public static <K, V> Builder<K, V> builderWithExpectedSize(int expectedSize) {
   }
 
   static void checkNoConflict(
-      boolean safe, String conflictDescription, Entry<?, ?> entry1, Entry<?, ?> entry2) {
+      boolean safe, String conflictDescription, Object entry1, Object entry2) {
     if (!safe) {
       throw conflictException(conflictDescription, entry1, entry2);
     }
@@ -230,7 +394,7 @@ static IllegalArgumentException conflictException(
    *         .put("one", 1)
    *         .put("two", 2)
    *         .put("three", 3)
-   *         .build();
+   *         .buildOrThrow();
    * }</pre>
    *
    * <p>For <i>small</i> immutable maps, the {@code ImmutableMap.of()} methods are even more
@@ -244,15 +408,15 @@ static IllegalArgumentException conflictException(
    * sort by keys, or call {@link #orderEntriesByValue(Comparator)}, which changes this builder to
    * sort entries by value.
    *
-   * <p>Builder instances can be reused - it is safe to call {@link #build} multiple times to build
-   * multiple maps in series. Each map is a superset of the maps created before it.
+   * <p>Builder instances can be reused - it is safe to call {@link #buildOrThrow} multiple times to
+   * build multiple maps in series. Each map is a superset of the maps created before it.
    *
    * @since 2.0
    */
   @DoNotMock
   public static class Builder<K, V> {
-    @Nullable Comparator<? super V> valueComparator;
-    Entry<K, V>[] entries;
+    @CheckForNull Comparator<? super V> valueComparator;
+    @Nullable Entry<K, V>[] entries;
     int size;
     boolean entriesUsed;
 
@@ -264,9 +428,9 @@ public Builder() {
       this(ImmutableCollection.Builder.DEFAULT_INITIAL_CAPACITY);
     }
 
-    @SuppressWarnings("unchecked")
+    @SuppressWarnings({"unchecked", "rawtypes"})
     Builder(int initialCapacity) {
-      this.entries = new Entry[initialCapacity];
+      this.entries = new @Nullable Entry[initialCapacity];
       this.size = 0;
       this.entriesUsed = false;
     }
@@ -281,8 +445,9 @@ private void ensureCapacity(int minCapacity) {
     }
 
     /**
-     * Associates {@code key} with {@code value} in the built map. Duplicate keys are not allowed,
-     * and will cause {@link #build} to fail.
+     * Associates {@code key} with {@code value} in the built map. If the same key is put more than
+     * once, {@link #buildOrThrow} will fail, while {@link #buildKeepingLast} will keep the last
+     * value put for that key.
      */
     @CanIgnoreReturnValue
     public Builder<K, V> put(K key, V value) {
@@ -294,8 +459,9 @@ public Builder<K, V> put(K key, V value) {
     }
 
     /**
-     * Adds the given {@code entry} to the map, making it immutable if necessary. Duplicate keys are
-     * not allowed, and will cause {@link #build} to fail.
+     * Adds the given {@code entry} to the map, making it immutable if necessary. If the same key is
+     * put more than once, {@link #buildOrThrow} will fail, while {@link #buildKeepingLast} will
+     * keep the last value put for that key.
      *
      * @since 11.0
      */
@@ -305,8 +471,9 @@ public Builder<K, V> put(Entry<? extends K, ? extends V> entry) {
     }
 
     /**
-     * Associates all of the given map's keys and values in the built map. Duplicate keys are not
-     * allowed, and will cause {@link #build} to fail.
+     * Associates all of the given map's keys and values in the built map. If the same key is put
+     * more than once, {@link #buildOrThrow} will fail, while {@link #buildKeepingLast} will keep
+     * the last value put for that key.
      *
      * @throws NullPointerException if any key or value in {@code map} is null
      */
@@ -316,8 +483,9 @@ public Builder<K, V> putAll(Map<? extends K, ? extends V> map) {
     }
 
     /**
-     * Adds all of the given entries to the built map. Duplicate keys are not allowed, and will
-     * cause {@link #build} to fail.
+     * Adds all of the given entries to the built map. If the same key is put more than once, {@link
+     * #buildOrThrow} will fail, while {@link #buildKeepingLast} will keep the last value put for
+     * that key.
      *
      * @throws NullPointerException if any key, value, or entry is null
      * @since 19.0
@@ -361,19 +529,7 @@ Builder<K, V> combine(Builder<K, V> other) {
       return this;
     }
 
-    /*
-     * TODO(kevinb): Should build() and the ImmutableBiMap & ImmutableSortedMap
-     * versions throw an IllegalStateException instead?
-     */
-
-    /**
-     * Returns a newly-created immutable map. The iteration order of the returned map is the order
-     * in which entries were inserted into the builder, unless {@link #orderEntriesByValue} was
-     * called, in which case entries are sorted by value.
-     *
-     * @throws IllegalArgumentException if duplicate keys were added
-     */
-    public ImmutableMap<K, V> build() {
+    private ImmutableMap<K, V> build(boolean throwIfDuplicateKeys) {
       /*
        * If entries is full, or if hash flooding is detected, then this implementation may end up
        * using the entries array directly and writing over the entry objects with non-terminal
@@ -381,22 +537,93 @@ public ImmutableMap<K, V> build() {
        * (so it can't affect the original array), and future build() calls will always copy any
        * entry objects that cannot be safely reused.
        */
-      if (valueComparator != null) {
-        if (entriesUsed) {
-          entries = Arrays.copyOf(entries, size);
-        }
-        Arrays.sort(
-            entries, 0, size, Ordering.from(valueComparator).onResultOf(Maps.<V>valueFunction()));
-      }
       switch (size) {
         case 0:
           return of();
         case 1:
-          return of(entries[0].getKey(), entries[0].getValue());
+          // requireNonNull is safe because the first `size` elements have been filled in.
+          Entry<K, V> onlyEntry = requireNonNull(entries[0]);
+          return of(onlyEntry.getKey(), onlyEntry.getValue());
         default:
-          entriesUsed = true;
-          return RegularImmutableMap.fromEntryArray(size, entries);
+          break;
       }
+      // localEntries is an alias for the entries field, except if we end up removing duplicates in
+      // a copy of the entries array. Likewise, localSize is the same as size except in that case.
+      // It's possible to keep using this Builder after calling buildKeepingLast(), so we need to
+      // ensure that its state is not corrupted by removing duplicates that should cause a later
+      // buildOrThrow() to fail, or by changing the size.
+      @Nullable Entry<K, V>[] localEntries;
+      int localSize = size;
+      if (valueComparator == null) {
+        localEntries = entries;
+      } else {
+        if (entriesUsed) {
+          entries = Arrays.copyOf(entries, size);
+        }
+        localEntries = entries;
+        if (!throwIfDuplicateKeys) {
+          // We want to retain only the last-put value for any given key, before sorting.
+          // This could be improved, but orderEntriesByValue is rather rarely used anyway.
+          @SuppressWarnings("nullness") // entries 0..size-1 are non-null
+          Entry<K, V>[] nonNullEntries = (Entry<K, V>[]) localEntries;
+          localEntries = lastEntryForEachKey(nonNullEntries, size);
+          localSize = localEntries.length;
+        }
+        Arrays.sort(
+            localEntries,
+            0,
+            localSize,
+            Ordering.from(valueComparator).onResultOf(Maps.<V>valueFunction()));
+      }
+      entriesUsed = true;
+      return RegularImmutableMap.fromEntryArray(localSize, localEntries, throwIfDuplicateKeys);
+    }
+
+    /**
+     * Returns a newly-created immutable map. The iteration order of the returned map is the order
+     * in which entries were inserted into the builder, unless {@link #orderEntriesByValue} was
+     * called, in which case entries are sorted by value.
+     *
+     * <p>Prefer the equivalent method {@link #buildOrThrow()} to make it explicit that the method
+     * will throw an exception if there are duplicate keys. The {@code build()} method will soon be
+     * deprecated.
+     *
+     * @throws IllegalArgumentException if duplicate keys were added
+     */
+    public ImmutableMap<K, V> build() {
+      return buildOrThrow();
+    }
+
+    /**
+     * Returns a newly-created immutable map, or throws an exception if any key was added more than
+     * once. The iteration order of the returned map is the order in which entries were inserted
+     * into the builder, unless {@link #orderEntriesByValue} was called, in which case entries are
+     * sorted by value.
+     *
+     * @throws IllegalArgumentException if duplicate keys were added
+     * @since 31.0
+     */
+    public ImmutableMap<K, V> buildOrThrow() {
+      return build(true);
+    }
+
+    /**
+     * Returns a newly-created immutable map, using the last value for any key that was added more
+     * than once. The iteration order of the returned map is the order in which entries were
+     * inserted into the builder, unless {@link #orderEntriesByValue} was called, in which case
+     * entries are sorted by value. If a key was added more than once, it appears in iteration order
+     * based on the first time it was added, again unless {@link #orderEntriesByValue} was called.
+     *
+     * <p>In the current implementation, all values associated with a given key are stored in the
+     * {@code Builder} object, even though only one of them will be used in the built map. If there
+     * can be many repeated keys, it may be more space-efficient to use a {@link
+     * java.util.LinkedHashMap LinkedHashMap} and {@link ImmutableMap#copyOf(Map)} rather than
+     * {@code ImmutableMap.Builder}.
+     *
+     * @since 31.1
+     */
+    public ImmutableMap<K, V> buildKeepingLast() {
+      return build(false);
     }
 
     @VisibleForTesting // only for testing JDK backed implementation
@@ -407,12 +634,35 @@ ImmutableMap<K, V> buildJdkBacked() {
         case 0:
           return of();
         case 1:
-          return of(entries[0].getKey(), entries[0].getValue());
+          // requireNonNull is safe because the first `size` elements have been filled in.
+          Entry<K, V> onlyEntry = requireNonNull(entries[0]);
+          return of(onlyEntry.getKey(), onlyEntry.getValue());
         default:
           entriesUsed = true;
-          return JdkBackedImmutableMap.create(size, entries);
+          return JdkBackedImmutableMap.create(size, entries, /* throwIfDuplicateKeys= */ true);
       }
     }
+
+    private static <K, V> Entry<K, V>[] lastEntryForEachKey(Entry<K, V>[] entries, int size) {
+      Set<K> seen = new HashSet<>();
+      BitSet dups = new BitSet(); // slots that are overridden by a later duplicate key
+      for (int i = size - 1; i >= 0; i--) {
+        if (!seen.add(entries[i].getKey())) {
+          dups.set(i);
+        }
+      }
+      if (dups.isEmpty()) {
+        return entries;
+      }
+      @SuppressWarnings({"rawtypes", "unchecked"})
+      Entry<K, V>[] newEntries = new Entry[size - dups.cardinality()];
+      for (int inI = 0, outI = 0; inI < size; inI++) {
+        if (!dups.get(inI)) {
+          newEntries[outI++] = entries[inI];
+        }
+      }
+      return newEntries;
+    }
   }
 
   /**
@@ -459,7 +709,8 @@ public static <K, V> ImmutableMap<K, V> copyOf(
       case 0:
         return of();
       case 1:
-        Entry<K, V> onlyEntry = entryArray[0];
+        // requireNonNull is safe because the first `size` elements have been filled in.
+        Entry<K, V> onlyEntry = requireNonNull(entryArray[0]);
         return of(onlyEntry.getKey(), onlyEntry.getValue());
       default:
         /*
@@ -473,7 +724,7 @@ public static <K, V> ImmutableMap<K, V> copyOf(
   private static <K extends Enum<K>, V> ImmutableMap<K, V> copyOfEnumMap(
       EnumMap<K, ? extends V> original) {
     EnumMap<K, V> copy = new EnumMap<>(original);
-    for (Entry<?, ?> entry : copy.entrySet()) {
+    for (Entry<K, V> entry : copy.entrySet()) {
       checkEntryNotNull(entry.getKey(), entry.getValue());
     }
     return ImmutableEnumMap.asImmutable(copy);
@@ -530,6 +781,7 @@ ImmutableCollection<V> createValues() {
   @Deprecated
   @Override
   @DoNotCall("Always throws UnsupportedOperationException")
+  @CheckForNull
   public final V put(K k, V v) {
     throw new UnsupportedOperationException();
   }
@@ -544,6 +796,7 @@ public final V put(K k, V v) {
   @Deprecated
   @Override
   @DoNotCall("Always throws UnsupportedOperationException")
+  @CheckForNull
   public final V putIfAbsent(K key, V value) {
     throw new UnsupportedOperationException();
   }
@@ -569,6 +822,7 @@ public final boolean replace(K key, V oldValue, V newValue) {
    */
   @Deprecated
   @Override
+  @CheckForNull
   @DoNotCall("Always throws UnsupportedOperationException")
   public final V replace(K key, V value) {
     throw new UnsupportedOperationException();
@@ -610,7 +864,8 @@ public final V computeIfPresent(
   @Deprecated
   @Override
   @DoNotCall("Always throws UnsupportedOperationException")
-  public final V compute(K key, BiFunction<? super K, ? super V, ? extends V> remappingFunction) {
+  public final V compute(
+      K key, BiFunction<? super K, ? super @Nullable V, ? extends V> remappingFunction) {
     throw new UnsupportedOperationException();
   }
 
@@ -663,7 +918,8 @@ public final void replaceAll(BiFunction<? super K, ? super V, ? extends V> funct
   @Deprecated
   @Override
   @DoNotCall("Always throws UnsupportedOperationException")
-  public final V remove(@Nullable Object o) {
+  @CheckForNull
+  public final V remove(@CheckForNull Object o) {
     throw new UnsupportedOperationException();
   }
 
@@ -676,7 +932,7 @@ public final V remove(@Nullable Object o) {
   @Deprecated
   @Override
   @DoNotCall("Always throws UnsupportedOperationException")
-  public final boolean remove(Object key, Object value) {
+  public final boolean remove(@CheckForNull Object key, @CheckForNull Object value) {
     throw new UnsupportedOperationException();
   }
 
@@ -701,19 +957,20 @@ public boolean isEmpty() {
 
   @Pure
   @Override
-  public boolean containsKey(@Nullable Object key) {
+  public boolean containsKey(@CheckForNull Object key) {
     return get(key) != null;
   }
 
   @Pure
   @Override
-  public boolean containsValue(@Nullable Object value) {
+  public boolean containsValue(@CheckForNull Object value) {
     return values().contains(value);
   }
 
   // Overriding to mark it Nullable
   @Override
-  public abstract @Nullable V get(@Nullable Object key);
+  @CheckForNull
+  public abstract V get(@CheckForNull Object key);
 
   /**
    * @since 21.0 (but only since 23.5 in the Android <a
@@ -721,12 +978,43 @@ public boolean containsValue(@Nullable Object value) {
    *     Note, however, that Java 8 users can call this method with any version and flavor of Guava.
    */
   @Override
-  public final V getOrDefault(@Nullable Object key, @Nullable V defaultValue) {
+  @CheckForNull
+  public final V getOrDefault(@CheckForNull Object key, @CheckForNull V defaultValue) {
+    /*
+     * Even though it's weird to pass a defaultValue that is null, some callers do so. Those who
+     * pass a literal "null" should probably just use `get`, but I would expect other callers to
+     * pass an expression that *might* be null. This could happen with:
+     *
+     * - a `getFooOrDefault(@CheckForNull Foo defaultValue)` method that returns
+     *   `map.getOrDefault(FOO_KEY, defaultValue)`
+     *
+     * - a call that consults a chain of maps, as in `mapA.getOrDefault(key, mapB.getOrDefault(key,
+     *   ...))`
+     *
+     * So it makes sense for the parameter (and thus the return type) to be @CheckForNull.
+     *
+     * Two other points:
+     *
+     * 1. We'll want to use something like @PolyNull once we can make that work for the various
+     * platforms we target.
+     *
+     * 2. Kotlin's Map type has a getOrDefault method that accepts and returns a "plain V," in
+     * contrast to the "V?" type that we're using. As a result, Kotlin sees a conflict between the
+     * nullness annotations in ImmutableMap and those in its own Map type. In response, it considers
+     * the parameter and return type both to be platform types. As a result, Kotlin permits calls
+     * that can lead to NullPointerException. That's unfortunate. But hopefully most Kotlin callers
+     * use `get(key) ?: defaultValue` instead of this method, anyway.
+     */
     V result = get(key);
-    return (result != null) ? result : defaultValue;
+    // TODO(b/192579700): Use a ternary once it no longer confuses our nullness checker.
+    if (result != null) {
+      return result;
+    } else {
+      return defaultValue;
+    }
   }
 
-  @LazyInit @RetainedWith private transient ImmutableSet<Entry<K, V>> entrySet;
+  @LazyInit @RetainedWith @CheckForNull private transient ImmutableSet<Entry<K, V>> entrySet;
 
   /**
    * Returns an immutable set of the mappings in this map. The iteration order is specified by the
@@ -741,7 +1029,7 @@ public ImmutableSet<Entry<K, V>> entrySet() {
 
   abstract ImmutableSet<Entry<K, V>> createEntrySet();
 
-  @LazyInit @RetainedWith private transient ImmutableSet<K> keySet;
+  @LazyInit @RetainedWith @CheckForNull private transient ImmutableSet<K> keySet;
 
   /**
    * Returns an immutable set of the keys in this map, in the same order that they appear in {@link
@@ -780,7 +1068,7 @@ Spliterator<K> keySpliterator() {
     return CollectSpliterators.map(entrySet().spliterator(), Entry::getKey);
   }
 
-  @LazyInit @RetainedWith private transient ImmutableCollection<V> values;
+  @LazyInit @RetainedWith @CheckForNull private transient ImmutableCollection<V> values;
 
   /**
    * Returns an immutable collection of the values in this map, in the same order that they appear
@@ -801,7 +1089,7 @@ public ImmutableCollection<V> values() {
   abstract ImmutableCollection<V> createValues();
 
   // cached so that this.multimapView().inverse() only computes inverse once
-  @LazyInit private transient ImmutableSetMultimap<K, V> multimapView;
+  @LazyInit @CheckForNull private transient ImmutableSetMultimap<K, V> multimapView;
 
   /**
    * Returns a multimap view of the map.
@@ -834,12 +1122,13 @@ ImmutableSet<K> createKeySet() {
     }
 
     @Override
-    public boolean containsKey(@Nullable Object key) {
+    public boolean containsKey(@CheckForNull Object key) {
       return ImmutableMap.this.containsKey(key);
     }
 
     @Override
-    public ImmutableSet<V> get(@Nullable Object key) {
+    @CheckForNull
+    public ImmutableSet<V> get(@CheckForNull Object key) {
       V outerValue = ImmutableMap.this.get(key);
       return (outerValue == null) ? null : ImmutableSet.of(outerValue);
     }
@@ -890,7 +1179,7 @@ public ImmutableSet<V> getValue() {
 
   @Pure
   @Override
-  public boolean equals(@Nullable Object object) {
+  public boolean equals(@CheckForNull Object object) {
     return Maps.equalsImpl(this, object);
   }
 
@@ -933,7 +1222,8 @@ static class SerializedForm<K, V> implements Serializable {
         Object[] keys = new Object[map.size()];
         Object[] values = new Object[map.size()];
         int i = 0;
-        for (Entry<?, ?> entry : map.entrySet()) {
+        // "extends Object" works around https://github.com/typetools/checker-framework/issues/3013
+        for (Entry<? extends Object, ? extends Object> entry : map.entrySet()) {
           keys[i] = entry.getKey();
           values[i] = entry.getValue();
           i++;
@@ -964,7 +1254,7 @@ final Object readResolve() {
         builder.put(keyIter.next(), valueIter.next());
       }
 
-      return builder.build();
+      return builder.buildOrThrow();
     }
 
     @SuppressWarnings("unchecked")
@@ -977,7 +1267,7 @@ final Object legacyReadResolve() {
       for (int i = 0; i < keys.length; i++) {
         builder.put(keys[i], values[i]);
       }
-      return builder.build();
+      return builder.buildOrThrow();
     }
 
     /**
diff --git a/guava/src/com/google/common/collect/ImmutableMapEntry.java b/guava/src/com/google/common/collect/ImmutableMapEntry.java
index d03d4fa0ea81..ac483d8fd8ee 100644
--- a/guava/src/com/google/common/collect/ImmutableMapEntry.java
+++ b/guava/src/com/google/common/collect/ImmutableMapEntry.java
@@ -19,7 +19,7 @@
 import static com.google.common.collect.CollectPreconditions.checkEntryNotNull;
 
 import com.google.common.annotations.GwtIncompatible;
-import org.checkerframework.checker.nullness.qual.Nullable;
+import javax.annotation.CheckForNull;
 
 /**
  * Implementation of {@code Entry} for {@link ImmutableMap} that adds extra methods to traverse hash
@@ -33,10 +33,16 @@
  * @author Louis Wasserman
  */
 @GwtIncompatible // unnecessary
+@ElementTypesAreNonnullByDefault
 class ImmutableMapEntry<K, V> extends ImmutableEntry<K, V> {
   /**
    * Creates an {@code ImmutableMapEntry} array to hold parameterized entries. The result must never
    * be upcast back to ImmutableMapEntry[] (or Object[], etc.), or allowed to escape the class.
+   *
+   * <p>The returned array has all its elements set to their initial null values. However, we don't
+   * declare it as {@code @Nullable ImmutableMapEntry[]} because our checker doesn't require newly
+   * created arrays to have a {@code @Nullable} element type even when they're created directly with
+   * {@code new ImmutableMapEntry[...]}, so it seems silly to insist on that only here.
    */
   @SuppressWarnings("unchecked") // Safe as long as the javadocs are followed
   static <K, V> ImmutableMapEntry<K, V>[] createEntryArray(int size) {
@@ -53,12 +59,12 @@ static <K, V> ImmutableMapEntry<K, V>[] createEntryArray(int size) {
     // null check would be redundant
   }
 
-  @Nullable
+  @CheckForNull
   ImmutableMapEntry<K, V> getNextInKeyBucket() {
     return null;
   }
 
-  @Nullable
+  @CheckForNull
   ImmutableMapEntry<K, V> getNextInValueBucket() {
     return null;
   }
@@ -72,15 +78,23 @@ boolean isReusable() {
   }
 
   static class NonTerminalImmutableMapEntry<K, V> extends ImmutableMapEntry<K, V> {
-    private final transient ImmutableMapEntry<K, V> nextInKeyBucket;
-
-    NonTerminalImmutableMapEntry(K key, V value, ImmutableMapEntry<K, V> nextInKeyBucket) {
+    /*
+     * Yes, we sometimes set nextInKeyBucket to null, even for this "non-terminal" entry. We don't
+     * do that with a plain NonTerminalImmutableMapEntry, but we do do it with the BiMap-specific
+     * subclass below. That's because the Entry might be non-terminal in the key bucket but terminal
+     * in the value bucket (or vice versa).
+     */
+    @CheckForNull private final transient ImmutableMapEntry<K, V> nextInKeyBucket;
+
+    NonTerminalImmutableMapEntry(
+        K key, V value, @CheckForNull ImmutableMapEntry<K, V> nextInKeyBucket) {
       super(key, value);
       this.nextInKeyBucket = nextInKeyBucket;
     }
 
     @Override
-    final @Nullable ImmutableMapEntry<K, V> getNextInKeyBucket() {
+    @CheckForNull
+    final ImmutableMapEntry<K, V> getNextInKeyBucket() {
       return nextInKeyBucket;
     }
 
@@ -92,19 +106,19 @@ final boolean isReusable() {
 
   static final class NonTerminalImmutableBiMapEntry<K, V>
       extends NonTerminalImmutableMapEntry<K, V> {
-    private final transient ImmutableMapEntry<K, V> nextInValueBucket;
+    @CheckForNull private final transient ImmutableMapEntry<K, V> nextInValueBucket;
 
     NonTerminalImmutableBiMapEntry(
         K key,
         V value,
-        ImmutableMapEntry<K, V> nextInKeyBucket,
-        ImmutableMapEntry<K, V> nextInValueBucket) {
+        @CheckForNull ImmutableMapEntry<K, V> nextInKeyBucket,
+        @CheckForNull ImmutableMapEntry<K, V> nextInValueBucket) {
       super(key, value, nextInKeyBucket);
       this.nextInValueBucket = nextInValueBucket;
     }
 
     @Override
-    @Nullable
+    @CheckForNull
     ImmutableMapEntry<K, V> getNextInValueBucket() {
       return nextInValueBucket;
     }
diff --git a/guava/src/com/google/common/collect/ImmutableMapEntrySet.java b/guava/src/com/google/common/collect/ImmutableMapEntrySet.java
index 830528364d9f..6f5503af5c11 100644
--- a/guava/src/com/google/common/collect/ImmutableMapEntrySet.java
+++ b/guava/src/com/google/common/collect/ImmutableMapEntrySet.java
@@ -22,6 +22,7 @@
 import java.util.Map.Entry;
 import java.util.Spliterator;
 import java.util.function.Consumer;
+import javax.annotation.CheckForNull;
 import org.checkerframework.checker.nullness.qual.Nullable;
 
 /**
@@ -31,7 +32,8 @@
  * @author Kevin Bourrillion
  */
 @GwtCompatible(emulated = true)
-abstract class ImmutableMapEntrySet<K, V> extends ImmutableSet<Entry<K, V>> {
+@ElementTypesAreNonnullByDefault
+abstract class ImmutableMapEntrySet<K, V> extends ImmutableSet.CachingAsList<Entry<K, V>> {
   static final class RegularEntrySet<K, V> extends ImmutableMapEntrySet<K, V> {
     private final transient ImmutableMap<K, V> map;
     private final transient ImmutableList<Entry<K, V>> entries;
@@ -52,7 +54,7 @@ ImmutableMap<K, V> map() {
 
     @Override
     @GwtIncompatible("not used in GWT")
-    int copyIntoArray(Object[] dst, int offset) {
+    int copyIntoArray(@Nullable Object[] dst, int offset) {
       return entries.copyIntoArray(dst, offset);
     }
 
@@ -87,7 +89,7 @@ public int size() {
   }
 
   @Override
-  public boolean contains(@Nullable Object object) {
+  public boolean contains(@CheckForNull Object object) {
     if (object instanceof Entry) {
       Entry<?, ?> entry = (Entry<?, ?>) object;
       V value = map().get(entry.getKey());
diff --git a/guava/src/com/google/common/collect/ImmutableMapKeySet.java b/guava/src/com/google/common/collect/ImmutableMapKeySet.java
index 0b28cc251b11..d10ee10e7a8f 100644
--- a/guava/src/com/google/common/collect/ImmutableMapKeySet.java
+++ b/guava/src/com/google/common/collect/ImmutableMapKeySet.java
@@ -23,7 +23,7 @@
 import java.io.Serializable;
 import java.util.Spliterator;
 import java.util.function.Consumer;
-import org.checkerframework.checker.nullness.qual.Nullable;
+import javax.annotation.CheckForNull;
 
 /**
  * {@code keySet()} implementation for {@link ImmutableMap}.
@@ -32,6 +32,7 @@
  * @author Kevin Bourrillion
  */
 @GwtCompatible(emulated = true)
+@ElementTypesAreNonnullByDefault
 final class ImmutableMapKeySet<K, V> extends IndexedImmutableSet<K> {
   private final ImmutableMap<K, V> map;
 
@@ -55,7 +56,7 @@ public Spliterator<K> spliterator() {
   }
 
   @Override
-  public boolean contains(@Nullable Object object) {
+  public boolean contains(@CheckForNull Object object) {
     return map.containsKey(object);
   }
 
diff --git a/guava/src/com/google/common/collect/ImmutableMapValues.java b/guava/src/com/google/common/collect/ImmutableMapValues.java
index 2950f907abcc..702191c6499d 100644
--- a/guava/src/com/google/common/collect/ImmutableMapValues.java
+++ b/guava/src/com/google/common/collect/ImmutableMapValues.java
@@ -24,7 +24,7 @@
 import java.util.Map.Entry;
 import java.util.Spliterator;
 import java.util.function.Consumer;
-import org.checkerframework.checker.nullness.qual.Nullable;
+import javax.annotation.CheckForNull;
 
 /**
  * {@code values()} implementation for {@link ImmutableMap}.
@@ -33,6 +33,7 @@
  * @author Kevin Bourrillion
  */
 @GwtCompatible(emulated = true)
+@ElementTypesAreNonnullByDefault
 final class ImmutableMapValues<K, V> extends ImmutableCollection<V> {
   private final ImmutableMap<K, V> map;
 
@@ -68,7 +69,7 @@ public Spliterator<V> spliterator() {
   }
 
   @Override
-  public boolean contains(@Nullable Object object) {
+  public boolean contains(@CheckForNull Object object) {
     return object != null && Iterators.contains(iterator(), object);
   }
 
diff --git a/guava/src/com/google/common/collect/ImmutableMultimap.java b/guava/src/com/google/common/collect/ImmutableMultimap.java
index f614124ced08..cb79fd7ce8f0 100644
--- a/guava/src/com/google/common/collect/ImmutableMultimap.java
+++ b/guava/src/com/google/common/collect/ImmutableMultimap.java
@@ -18,11 +18,14 @@
 
 import static com.google.common.base.Preconditions.checkNotNull;
 import static com.google.common.collect.CollectPreconditions.checkEntryNotNull;
+import static com.google.common.collect.Maps.immutableEntry;
+import static java.util.Objects.requireNonNull;
 
 import com.google.common.annotations.Beta;
 import com.google.common.annotations.GwtCompatible;
 import com.google.common.annotations.GwtIncompatible;
 import com.google.errorprone.annotations.CanIgnoreReturnValue;
+import com.google.errorprone.annotations.DoNotCall;
 import com.google.errorprone.annotations.DoNotMock;
 import com.google.j2objc.annotations.Weak;
 import com.google.j2objc.annotations.WeakOuter;
@@ -37,6 +40,7 @@
 import java.util.Set;
 import java.util.Spliterator;
 import java.util.function.BiConsumer;
+import javax.annotation.CheckForNull;
 import org.checkerframework.checker.nullness.qual.Nullable;
 import org.checkerframework.dataflow.qual.Pure;
 import org.checkerframework.dataflow.qual.SideEffectFree;
@@ -63,17 +67,22 @@
  * immediately after the last entry having that key.
  *
  * <p>See the Guava User Guide article on <a href=
- * "https://github.com/google/guava/wiki/ImmutableCollectionsExplained"> immutable collections</a>.
+ * "https://github.com/google/guava/wiki/ImmutableCollectionsExplained">immutable collections</a>.
  *
  * @author Jared Levy
  * @since 2.0
  */
 @AnnotatedFor({"nullness"})
 @GwtCompatible(emulated = true)
+@ElementTypesAreNonnullByDefault
 public abstract class ImmutableMultimap<K, V> extends BaseImmutableMultimap<K, V>
     implements Serializable {
 
-  /** Returns an empty multimap. */
+  /**
+   * Returns an empty multimap.
+   *
+   * <p><b>Performance note:</b> the instance returned is a singleton.
+   */
   public static <K, V> ImmutableMultimap<K, V> of() {
     return ImmutableListMultimap.of();
   }
@@ -144,9 +153,9 @@ public static <K, V> Builder<K, V> builder() {
    */
   @DoNotMock
   public static class Builder<K, V> {
-    Map<K, Collection<V>> builderMap;
-    @Nullable Comparator<? super K> keyComparator;
-    @Nullable Comparator<? super V> valueComparator;
+    final Map<K, Collection<V>> builderMap;
+    @CheckForNull Comparator<? super K> keyComparator;
+    @CheckForNull Comparator<? super V> valueComparator;
 
     /**
      * Creates a new builder. The returned builder is equivalent to the builder generated by {@link
@@ -362,7 +371,11 @@ static class FieldSettersHolder {
   @CanIgnoreReturnValue
   @Deprecated
   @Override
-  public ImmutableCollection<V> removeAll(@Nullable Object key) {
+  @DoNotCall("Always throws UnsupportedOperationException")
+  // DoNotCall wants this to be final, but we want to override it to return more specific types.
+  // Inheritance is closed, and all subtypes are @DoNotCall, so this is safe to suppress.
+  @SuppressWarnings("DoNotCall")
+  public ImmutableCollection<V> removeAll(@CheckForNull Object key) {
     throw new UnsupportedOperationException();
   }
 
@@ -375,6 +388,10 @@ public ImmutableCollection<V> removeAll(@Nullable Object key) {
   @CanIgnoreReturnValue
   @Deprecated
   @Override
+  @DoNotCall("Always throws UnsupportedOperationException")
+  // DoNotCall wants this to be final, but we want to override it to return more specific types.
+  // Inheritance is closed, and all subtypes are @DoNotCall, so this is safe to suppress.
+  @SuppressWarnings("DoNotCall")
   public ImmutableCollection<V> replaceValues(K key, Iterable<? extends V> values) {
     throw new UnsupportedOperationException();
   }
@@ -387,7 +404,8 @@ public ImmutableCollection<V> replaceValues(K key, Iterable<? extends V> values)
    */
   @Deprecated
   @Override
-  public void clear() {
+  @DoNotCall("Always throws UnsupportedOperationException")
+  public final void clear() {
     throw new UnsupportedOperationException();
   }
 
@@ -416,7 +434,8 @@ public void clear() {
   @CanIgnoreReturnValue
   @Deprecated
   @Override
-  public boolean put(K key, V value) {
+  @DoNotCall("Always throws UnsupportedOperationException")
+  public final boolean put(K key, V value) {
     throw new UnsupportedOperationException();
   }
 
@@ -429,7 +448,8 @@ public boolean put(K key, V value) {
   @CanIgnoreReturnValue
   @Deprecated
   @Override
-  public boolean putAll(K key, Iterable<? extends V> values) {
+  @DoNotCall("Always throws UnsupportedOperationException")
+  public final boolean putAll(K key, Iterable<? extends V> values) {
     throw new UnsupportedOperationException();
   }
 
@@ -442,7 +462,8 @@ public boolean putAll(K key, Iterable<? extends V> values) {
   @CanIgnoreReturnValue
   @Deprecated
   @Override
-  public boolean putAll(Multimap<? extends K, ? extends V> multimap) {
+  @DoNotCall("Always throws UnsupportedOperationException")
+  public final boolean putAll(Multimap<? extends K, ? extends V> multimap) {
     throw new UnsupportedOperationException();
   }
 
@@ -455,7 +476,8 @@ public boolean putAll(Multimap<? extends K, ? extends V> multimap) {
   @CanIgnoreReturnValue
   @Deprecated
   @Override
-  public boolean remove(@Nullable Object key, @Nullable Object value) {
+  @DoNotCall("Always throws UnsupportedOperationException")
+  public final boolean remove(@CheckForNull Object key, @CheckForNull Object value) {
     throw new UnsupportedOperationException();
   }
 
@@ -473,13 +495,13 @@ boolean isPartialView() {
 
   @Pure
   @Override
-  public boolean containsKey(@Nullable Object key) {
+  public boolean containsKey(@CheckForNull Object key) {
     return map.containsKey(key);
   }
 
   @Pure
   @Override
-  public boolean containsValue(@Nullable Object value) {
+  public boolean containsValue(@CheckForNull Object value) {
     return value != null && super.containsValue(value);
   }
 
@@ -558,7 +580,7 @@ public int size() {
 
     @Pure
     @Override
-    public boolean contains(@Nullable Object object) {
+    public boolean contains(@CheckForNull Object object) {
       if (object instanceof Entry) {
         Entry<?, ?> entry = (Entry<?, ?>) object;
         return multimap.containsEntry(entry.getKey(), entry.getValue());
@@ -574,7 +596,7 @@ UnmodifiableIterator<Entry<K, V>> entryIterator() {
     return new UnmodifiableIterator<Entry<K, V>>() {
       final Iterator<? extends Entry<K, ? extends ImmutableCollection<V>>> asMapItr =
           map.entrySet().iterator();
-      K currentKey = null;
+      @CheckForNull K currentKey = null;
       Iterator<V> valueItr = Iterators.emptyIterator();
 
       @Override
@@ -589,7 +611,11 @@ public Entry<K, V> next() {
           currentKey = entry.getKey();
           valueItr = entry.getValue().iterator();
         }
-        return Maps.immutableEntry(currentKey, valueItr.next());
+        /*
+         * requireNonNull is safe: The first call to this method always enters the !hasNext() case
+         * and populates currentKey, after which it's never cleared.
+         */
+        return immutableEntry(requireNonNull(currentKey), valueItr.next());
       }
     };
   }
@@ -635,12 +661,12 @@ ImmutableMultiset<K> createKeys() {
   @WeakOuter
   class Keys extends ImmutableMultiset<K> {
     @Override
-    public boolean contains(@Nullable Object object) {
+    public boolean contains(@CheckForNull Object object) {
       return containsKey(object);
     }
 
     @Override
-    public int count(@Nullable Object element) {
+    public int count(@CheckForNull Object element) {
       Collection<V> values = map.get(element);
       return (values == null) ? 0 : values.size();
     }
@@ -730,7 +756,7 @@ private static final class Values<K, V> extends ImmutableCollection<V> {
     }
 
     @Override
-    public boolean contains(@Nullable Object object) {
+    public boolean contains(@CheckForNull Object object) {
       return multimap.containsValue(object);
     }
 
@@ -741,7 +767,7 @@ public UnmodifiableIterator<V> iterator() {
 
     @GwtIncompatible // not present in emulated superclass
     @Override
-    int copyIntoArray(Object[] dst, int offset) {
+    int copyIntoArray(@Nullable Object[] dst, int offset) {
       for (ImmutableCollection<V> valueCollection : multimap.map.values()) {
         offset = valueCollection.copyIntoArray(dst, offset);
       }
diff --git a/guava/src/com/google/common/collect/ImmutableMultiset.java b/guava/src/com/google/common/collect/ImmutableMultiset.java
index 5e9f76951bfc..6ba1a8f69392 100644
--- a/guava/src/com/google/common/collect/ImmutableMultiset.java
+++ b/guava/src/com/google/common/collect/ImmutableMultiset.java
@@ -17,6 +17,7 @@
 package com.google.common.collect;
 
 import static com.google.common.base.Preconditions.checkNotNull;
+import static java.util.Objects.requireNonNull;
 
 import com.google.common.annotations.GwtCompatible;
 import com.google.common.annotations.GwtIncompatible;
@@ -34,6 +35,7 @@
 import java.util.function.Function;
 import java.util.function.ToIntFunction;
 import java.util.stream.Collector;
+import javax.annotation.CheckForNull;
 import org.checkerframework.checker.nullness.qual.Nullable;
 import org.checkerframework.dataflow.qual.Pure;
 import org.checkerframework.dataflow.qual.SideEffectFree;
@@ -48,7 +50,7 @@
  * element when the multiset was created.
  *
  * <p>See the Guava User Guide article on <a href=
- * "https://github.com/google/guava/wiki/ImmutableCollectionsExplained"> immutable collections</a>.
+ * "https://github.com/google/guava/wiki/ImmutableCollectionsExplained">immutable collections</a>.
  *
  * @author Jared Levy
  * @author Louis Wasserman
@@ -57,6 +59,7 @@
 @AnnotatedFor({"nullness"})
 @GwtCompatible(serializable = true, emulated = true)
 @SuppressWarnings("serial") // we're overriding default serialization
+@ElementTypesAreNonnullByDefault
 public abstract class ImmutableMultiset<E> extends ImmutableMultisetGwtSerializationDependencies<E>
     implements Multiset<E> {
 
@@ -82,12 +85,18 @@ public abstract class ImmutableMultiset<E> extends ImmutableMultisetGwtSerializa
    *
    * @since 22.0
    */
-  public static <T, E> Collector<T, ?, ImmutableMultiset<E>> toImmutableMultiset(
-      Function<? super T, ? extends E> elementFunction, ToIntFunction<? super T> countFunction) {
+  public static <T extends @Nullable Object, E>
+      Collector<T, ?, ImmutableMultiset<E>> toImmutableMultiset(
+          Function<? super T, ? extends E> elementFunction,
+          ToIntFunction<? super T> countFunction) {
     return CollectCollectors.toImmutableMultiset(elementFunction, countFunction);
   }
 
-  /** Returns the empty immutable multiset. */
+  /**
+   * Returns the empty immutable multiset.
+   *
+   * <p><b>Performance note:</b> the instance returned is a singleton.
+   */
   @SuppressWarnings("unchecked") // all supported methods are covariant
   public static <E> ImmutableMultiset<E> of() {
     return (ImmutableMultiset<E>) RegularImmutableMultiset.EMPTY;
@@ -99,7 +108,6 @@ public static <E> ImmutableMultiset<E> of() {
    * @throws NullPointerException if {@code element} is null
    * @since 6.0 (source-compatible since 2.0)
    */
-  @SuppressWarnings("unchecked") // generic array created but never written
   public static <E> ImmutableMultiset<E> of(E element) {
     return copyFromElements(element);
   }
@@ -110,7 +118,6 @@ public static <E> ImmutableMultiset<E> of(E element) {
    * @throws NullPointerException if any element is null
    * @since 6.0 (source-compatible since 2.0)
    */
-  @SuppressWarnings("unchecked") //
   public static <E> ImmutableMultiset<E> of(E e1, E e2) {
     return copyFromElements(e1, e2);
   }
@@ -122,7 +129,6 @@ public static <E> ImmutableMultiset<E> of(E e1, E e2) {
    * @throws NullPointerException if any element is null
    * @since 6.0 (source-compatible since 2.0)
    */
-  @SuppressWarnings("unchecked") //
   public static <E> ImmutableMultiset<E> of(E e1, E e2, E e3) {
     return copyFromElements(e1, e2, e3);
   }
@@ -134,7 +140,6 @@ public static <E> ImmutableMultiset<E> of(E e1, E e2, E e3) {
    * @throws NullPointerException if any element is null
    * @since 6.0 (source-compatible since 2.0)
    */
-  @SuppressWarnings("unchecked") //
   public static <E> ImmutableMultiset<E> of(E e1, E e2, E e3, E e4) {
     return copyFromElements(e1, e2, e3, e4);
   }
@@ -146,7 +151,6 @@ public static <E> ImmutableMultiset<E> of(E e1, E e2, E e3, E e4) {
    * @throws NullPointerException if any element is null
    * @since 6.0 (source-compatible since 2.0)
    */
-  @SuppressWarnings("unchecked") //
   public static <E> ImmutableMultiset<E> of(E e1, E e2, E e3, E e4, E e5) {
     return copyFromElements(e1, e2, e3, e4, e5);
   }
@@ -158,7 +162,6 @@ public static <E> ImmutableMultiset<E> of(E e1, E e2, E e3, E e4, E e5) {
    * @throws NullPointerException if any element is null
    * @since 6.0 (source-compatible since 2.0)
    */
-  @SuppressWarnings("unchecked") //
   public static <E> ImmutableMultiset<E> of(E e1, E e2, E e3, E e4, E e5, E e6, E... others) {
     return new Builder<E>().add(e1).add(e2).add(e3).add(e4).add(e5).add(e6).add(others).build();
   }
@@ -231,7 +234,7 @@ public UnmodifiableIterator<E> iterator() {
     final Iterator<Entry<E>> entryIterator = entrySet().iterator();
     return new UnmodifiableIterator<E>() {
       int remaining;
-      @Nullable E element;
+      @CheckForNull E element;
 
       @Override
       public boolean hasNext() {
@@ -246,12 +249,16 @@ public E next() {
           remaining = entry.getCount();
         }
         remaining--;
-        return element;
+        /*
+         * requireNonNull is safe because `remaining` starts at 0, forcing us to initialize
+         * `element` above. After that, we never clear it.
+         */
+        return requireNonNull(element);
       }
     };
   }
 
-  @LazyInit private transient ImmutableList<E> asList;
+  @LazyInit @CheckForNull private transient ImmutableList<E> asList;
 
   @Pure
   @Override
@@ -261,7 +268,7 @@ public ImmutableList<E> asList() {
   }
 
   @Override
-  public boolean contains(@Nullable Object object) {
+  public boolean contains(@CheckForNull Object object) {
     return count(object) > 0;
   }
 
@@ -289,7 +296,7 @@ public final int add(E element, int occurrences) {
   @Deprecated
   @Override
   @DoNotCall("Always throws UnsupportedOperationException")
-  public final int remove(@Nullable Object element, int occurrences) {
+  public final int remove(@CheckForNull Object element, int occurrences) {
     throw new UnsupportedOperationException();
   }
 
@@ -323,7 +330,7 @@ public final boolean setCount(E element, int oldCount, int newCount) {
 
   @GwtIncompatible // not present in emulated superclass
   @Override
-  int copyIntoArray(Object[] dst, int offset) {
+  int copyIntoArray(@Nullable Object[] dst, int offset) {
     for (Multiset.Entry<E> entry : entrySet()) {
       Arrays.fill(dst, offset, offset + entry.getCount(), entry.getElement());
       offset += entry.getCount();
@@ -333,7 +340,7 @@ int copyIntoArray(Object[] dst, int offset) {
 
   @Pure
   @Override
-  public boolean equals(@Nullable Object object) {
+  public boolean equals(@CheckForNull Object object) {
     return Multisets.equalsImpl(this, object);
   }
 
@@ -353,7 +360,7 @@ public String toString() {
   @Override
   public abstract ImmutableSet<E> elementSet();
 
-  @LazyInit private transient ImmutableSet<Entry<E>> entrySet;
+  @LazyInit @CheckForNull private transient ImmutableSet<Entry<E>> entrySet;
 
   @SideEffectFree
   @Override
@@ -388,7 +395,7 @@ public int size() {
 
     @Pure
     @Override
-    public boolean contains(@Nullable Object o) {
+    public boolean contains(@CheckForNull Object o) {
       if (o instanceof Entry) {
         Entry<?> entry = (Entry<?>) o;
         if (entry.getCount() <= 0) {
@@ -604,7 +611,7 @@ E get(int index) {
     }
 
     @Override
-    public boolean contains(@Nullable Object object) {
+    public boolean contains(@CheckForNull Object object) {
       return delegate.contains(object);
     }
 
@@ -623,12 +630,13 @@ static final class SerializedForm implements Serializable {
     final Object[] elements;
     final int[] counts;
 
-    SerializedForm(Multiset<?> multiset) {
+    // "extends Object" works around https://github.com/typetools/checker-framework/issues/3013
+    SerializedForm(Multiset<? extends Object> multiset) {
       int distinct = multiset.entrySet().size();
       elements = new Object[distinct];
       counts = new int[distinct];
       int i = 0;
-      for (Entry<?> entry : multiset.entrySet()) {
+      for (Entry<? extends Object> entry : multiset.entrySet()) {
         elements[i] = entry.getElement();
         counts[i] = entry.getCount();
         i++;
diff --git a/guava/src/com/google/common/collect/ImmutableMultisetGwtSerializationDependencies.java b/guava/src/com/google/common/collect/ImmutableMultisetGwtSerializationDependencies.java
index a8b1899d280c..2469a188a2a6 100644
--- a/guava/src/com/google/common/collect/ImmutableMultisetGwtSerializationDependencies.java
+++ b/guava/src/com/google/common/collect/ImmutableMultisetGwtSerializationDependencies.java
@@ -37,4 +37,5 @@
  * and make types non-final.
  */
 @GwtCompatible(emulated = true)
+@ElementTypesAreNonnullByDefault
 abstract class ImmutableMultisetGwtSerializationDependencies<E> extends ImmutableCollection<E> {}
diff --git a/guava/src/com/google/common/collect/ImmutableRangeMap.java b/guava/src/com/google/common/collect/ImmutableRangeMap.java
index 931da96bb94b..e1979ab65fe9 100644
--- a/guava/src/com/google/common/collect/ImmutableRangeMap.java
+++ b/guava/src/com/google/common/collect/ImmutableRangeMap.java
@@ -34,6 +34,7 @@
 import java.util.function.BiFunction;
 import java.util.function.Function;
 import java.util.stream.Collector;
+import javax.annotation.CheckForNull;
 import org.checkerframework.checker.nullness.qual.Nullable;
 
 /**
@@ -45,6 +46,7 @@
  */
 @Beta
 @GwtIncompatible // NavigableMap
+@ElementTypesAreNonnullByDefault
 public class ImmutableRangeMap<K extends Comparable<?>, V> implements RangeMap<K, V>, Serializable {
 
   private static final ImmutableRangeMap<Comparable<?>, Object> EMPTY =
@@ -56,14 +58,18 @@ public class ImmutableRangeMap<K extends Comparable<?>, V> implements RangeMap<K
    *
    * @since 23.1
    */
-  public static <T, K extends Comparable<? super K>, V>
+  public static <T extends @Nullable Object, K extends Comparable<? super K>, V>
       Collector<T, ?, ImmutableRangeMap<K, V>> toImmutableRangeMap(
           Function<? super T, Range<K>> keyFunction,
           Function<? super T, ? extends V> valueFunction) {
     return CollectCollectors.toImmutableRangeMap(keyFunction, valueFunction);
   }
 
-  /** Returns an empty immutable range map. */
+  /**
+   * Returns an empty immutable range map.
+   *
+   * <p><b>Performance note:</b> the instance returned is a singleton.
+   */
   @SuppressWarnings("unchecked")
   public static <K extends Comparable<?>, V> ImmutableRangeMap<K, V> of() {
     return (ImmutableRangeMap<K, V>) EMPTY;
@@ -172,7 +178,8 @@ public ImmutableRangeMap<K, V> build() {
   }
 
   @Override
-  public @Nullable V get(K key) {
+  @CheckForNull
+  public V get(K key) {
     int index =
         SortedLists.binarySearch(
             ranges,
@@ -189,7 +196,8 @@ public ImmutableRangeMap<K, V> build() {
   }
 
   @Override
-  public @Nullable Entry<Range<K>, V> getEntry(K key) {
+  @CheckForNull
+  public Entry<Range<K>, V> getEntry(K key) {
     int index =
         SortedLists.binarySearch(
             ranges,
@@ -291,8 +299,8 @@ public final void remove(Range<K> range) {
   @DoNotCall("Always throws UnsupportedOperationException")
   public final void merge(
       Range<K> range,
-      @Nullable V value,
-      BiFunction<? super V, ? super V, ? extends V> remappingFunction) {
+      @CheckForNull V value,
+      BiFunction<? super V, ? super @Nullable V, ? extends @Nullable V> remappingFunction) {
     throw new UnsupportedOperationException();
   }
 
@@ -383,7 +391,7 @@ public int hashCode() {
   }
 
   @Override
-  public boolean equals(@Nullable Object o) {
+  public boolean equals(@CheckForNull Object o) {
     if (o instanceof RangeMap) {
       RangeMap<?, ?> rangeMap = (RangeMap<?, ?>) o;
       return asMapOfRanges().equals(rangeMap.asMapOfRanges());
diff --git a/guava/src/com/google/common/collect/ImmutableRangeSet.java b/guava/src/com/google/common/collect/ImmutableRangeSet.java
index 944c0d97121e..f279aae0c56b 100644
--- a/guava/src/com/google/common/collect/ImmutableRangeSet.java
+++ b/guava/src/com/google/common/collect/ImmutableRangeSet.java
@@ -20,6 +20,7 @@
 import static com.google.common.collect.SortedLists.KeyAbsentBehavior.NEXT_HIGHER;
 import static com.google.common.collect.SortedLists.KeyAbsentBehavior.NEXT_LOWER;
 import static com.google.common.collect.SortedLists.KeyPresentBehavior.ANY_PRESENT;
+import static java.util.Objects.requireNonNull;
 
 import com.google.common.annotations.Beta;
 import com.google.common.annotations.GwtIncompatible;
@@ -36,7 +37,7 @@
 import java.util.NoSuchElementException;
 import java.util.Set;
 import java.util.stream.Collector;
-import org.checkerframework.checker.nullness.qual.Nullable;
+import javax.annotation.CheckForNull;
 
 /**
  * A {@link RangeSet} whose contents will never change, with many other important properties
@@ -47,6 +48,7 @@
  */
 @Beta
 @GwtIncompatible
+@ElementTypesAreNonnullByDefault
 public final class ImmutableRangeSet<C extends Comparable> extends AbstractRangeSet<C>
     implements Serializable {
 
@@ -68,7 +70,11 @@ public final class ImmutableRangeSet<C extends Comparable> extends AbstractRange
     return CollectCollectors.toImmutableRangeSet();
   }
 
-  /** Returns an empty immutable range set. */
+  /**
+   * Returns an empty immutable range set.
+   *
+   * <p><b>Performance note:</b> the instance returned is a singleton.
+   */
   @SuppressWarnings("unchecked")
   public static <C extends Comparable> ImmutableRangeSet<C> of() {
     return (ImmutableRangeSet<C>) EMPTY;
@@ -182,6 +188,7 @@ public boolean encloses(Range<C> otherRange) {
   }
 
   @Override
+  @CheckForNull
   public Range<C> rangeContaining(C value) {
     int index =
         SortedLists.binarySearch(
@@ -305,7 +312,7 @@ public ImmutableSet<Range<C>> asDescendingSetOfRanges() {
     return new RegularImmutableSortedSet<>(ranges.reverse(), Range.<C>rangeLexOrdering().reverse());
   }
 
-  @LazyInit private transient ImmutableRangeSet<C> complement;
+  @LazyInit @CheckForNull private transient ImmutableRangeSet<C> complement;
 
   private final class ComplementRanges extends ImmutableList<Range<C>> {
     // True if the "positive" range set is empty or bounded below.
@@ -547,7 +554,7 @@ private final class AsSet extends ImmutableSortedSet<C> {
       this.domain = domain;
     }
 
-    private transient @Nullable Integer size;
+    @CheckForNull private transient Integer size;
 
     @Override
     public int size() {
@@ -573,6 +580,7 @@ public UnmodifiableIterator<C> iterator() {
         Iterator<C> elemItr = Iterators.emptyIterator();
 
         @Override
+        @CheckForNull
         protected C computeNext() {
           while (!elemItr.hasNext()) {
             if (rangeItr.hasNext()) {
@@ -594,6 +602,7 @@ public UnmodifiableIterator<C> descendingIterator() {
         Iterator<C> elemItr = Iterators.emptyIterator();
 
         @Override
+        @CheckForNull
         protected C computeNext() {
           while (!elemItr.hasNext()) {
             if (rangeItr.hasNext()) {
@@ -634,7 +643,7 @@ ImmutableSortedSet<C> tailSetImpl(C fromElement, boolean inclusive) {
     }
 
     @Override
-    public boolean contains(@Nullable Object o) {
+    public boolean contains(@CheckForNull Object o) {
       if (o == null) {
         return false;
       }
@@ -648,10 +657,10 @@ public boolean contains(@Nullable Object o) {
     }
 
     @Override
-    int indexOf(Object target) {
+    int indexOf(@CheckForNull Object target) {
       if (contains(target)) {
         @SuppressWarnings("unchecked") // if it's contained, it's definitely a C
-        C c = (C) target;
+        C c = (C) requireNonNull(target);
         long total = 0;
         for (Range<C> range : ranges) {
           if (range.contains(c)) {
diff --git a/guava/src/com/google/common/collect/ImmutableSet.java b/guava/src/com/google/common/collect/ImmutableSet.java
index 9ee2d958c184..964a873e3a4d 100644
--- a/guava/src/com/google/common/collect/ImmutableSet.java
+++ b/guava/src/com/google/common/collect/ImmutableSet.java
@@ -19,6 +19,7 @@
 import static com.google.common.base.Preconditions.checkArgument;
 import static com.google.common.base.Preconditions.checkNotNull;
 import static com.google.common.collect.CollectPreconditions.checkNonnegative;
+import static java.util.Objects.requireNonNull;
 
 import com.google.common.annotations.Beta;
 import com.google.common.annotations.GwtCompatible;
@@ -40,6 +41,7 @@
 import java.util.Spliterator;
 import java.util.function.Consumer;
 import java.util.stream.Collector;
+import javax.annotation.CheckForNull;
 import org.checkerframework.checker.nullness.qual.NonNull;
 import org.checkerframework.checker.nullness.qual.Nullable;
 import org.checkerframework.dataflow.qual.Pure;
@@ -54,8 +56,8 @@
 @AnnotatedFor({"nullness"})
 @GwtCompatible(serializable = true, emulated = true)
 @SuppressWarnings("serial") // we're overriding default serialization
-public abstract class ImmutableSet<E extends @NonNull Object> extends ImmutableCollection<E>
-    implements Set<E> {
+@ElementTypesAreNonnullByDefault
+public abstract class ImmutableSet<E> extends ImmutableCollection<E> implements Set<E> {
   static final int SPLITERATOR_CHARACTERISTICS =
       ImmutableCollection.SPLITERATOR_CHARACTERISTICS | Spliterator.DISTINCT;
 
@@ -74,6 +76,8 @@ public abstract class ImmutableSet<E extends @NonNull Object> extends ImmutableC
   /**
    * Returns the empty immutable set. Preferred over {@link Collections#emptySet} for code
    * consistency, and because the return type conveys the immutability guarantee.
+   *
+   * <p><b>Performance note:</b> the instance returned is a singleton.
    */
   @SuppressWarnings({"unchecked"}) // fully variant implementation (never actually produces any Es)
   public static <E> ImmutableSet<E> of() {
@@ -314,7 +318,7 @@ boolean isHashCodeFast() {
 
   @Pure
   @Override
-  public boolean equals(@Nullable Object object) {
+  public boolean equals(@CheckForNull Object object) {
     if (object == this) {
       return true;
     }
@@ -338,19 +342,26 @@ public int hashCode() {
   @Override
   public abstract UnmodifiableIterator<E> iterator();
 
-  @LazyInit @RetainedWith private transient @Nullable ImmutableList<E> asList;
+  @GwtCompatible
+  abstract static class CachingAsList<E> extends ImmutableSet<E> {
+    @LazyInit @RetainedWith @CheckForNull private transient ImmutableList<E> asList;
 
-  @Override
-  public ImmutableList<E> asList() {
-    ImmutableList<E> result = asList;
-    return (result == null) ? asList = createAsList() : result;
-  }
+    @Override
+    public ImmutableList<E> asList() {
+      ImmutableList<E> result = asList;
+      if (result == null) {
+        return asList = createAsList();
+      } else {
+        return result;
+      }
+    }
 
-  ImmutableList<E> createAsList() {
-    return new RegularImmutableAsList<E>(this, toArray());
+    ImmutableList<E> createAsList() {
+      return new RegularImmutableAsList<E>(this, toArray());
+    }
   }
 
-  abstract static class Indexed<E> extends ImmutableSet<E> {
+  abstract static class Indexed<E> extends CachingAsList<E> {
     abstract E get(int index);
 
     @Override
@@ -373,7 +384,7 @@ public void forEach(Consumer<? super E> consumer) {
     }
 
     @Override
-    int copyIntoArray(Object[] dst, int offset) {
+    int copyIntoArray(@Nullable Object[] dst, int offset) {
       return asList().copyIntoArray(dst, offset);
     }
 
@@ -445,24 +456,6 @@ public static <E> Builder<E> builderWithExpectedSize(int expectedSize) {
     return new Builder<E>(expectedSize);
   }
 
-  /** Builds a new open-addressed hash table from the first n objects in elements. */
-  static Object[] rebuildHashTable(int newTableSize, Object[] elements, int n) {
-    Object[] hashTable = new Object[newTableSize];
-    int mask = hashTable.length - 1;
-    for (int i = 0; i < n; i++) {
-      Object e = elements[i];
-      int j0 = Hashing.smear(e.hashCode());
-      for (int j = j0; ; j++) {
-        int index = j & mask;
-        if (hashTable[index] == null) {
-          hashTable[index] = e;
-          break;
-        }
-      }
-    }
-    return hashTable;
-  }
-
   /**
    * A builder for creating {@code ImmutableSet} instances. Example:
    *
@@ -481,16 +474,25 @@ static Object[] rebuildHashTable(int newTableSize, Object[] elements, int n) {
    *
    * @since 2.0
    */
-  public static class Builder<E extends @NonNull Object> extends ImmutableCollection.Builder<E> {
-    private SetBuilderImpl<E> impl;
+  public static class Builder<E> extends ImmutableCollection.Builder<E> {
+    /*
+     * `impl` is null only for instances of the subclass, ImmutableSortedSet.Builder. That subclass
+     * overrides all the methods that access it here. Thus, all the methods here can safely assume
+     * that this field is non-null.
+     */
+    @CheckForNull private SetBuilderImpl<E> impl;
     boolean forceCopy;
 
     public Builder() {
-      this(DEFAULT_INITIAL_CAPACITY);
+      this(0);
     }
 
     Builder(int capacity) {
-      impl = new RegularSetBuilderImpl<E>(capacity);
+      if (capacity > 0) {
+        impl = new RegularSetBuilderImpl<E>(capacity);
+      } else {
+        impl = EmptySetBuilderImpl.instance();
+      }
     }
 
     Builder(@SuppressWarnings("unused") boolean subclass) {
@@ -499,6 +501,7 @@ public Builder() {
 
     @VisibleForTesting
     void forceJdk() {
+      requireNonNull(impl); // see the comment on the field
       this.impl = new JdkBackedSetBuilderImpl<E>(impl);
     }
 
@@ -510,12 +513,14 @@ final void copyIfNecessary() {
     }
 
     void copy() {
+      requireNonNull(impl); // see the comment on the field
       impl = impl.copy();
     }
 
     @Override
     @CanIgnoreReturnValue
     public Builder<E> add(E element) {
+      requireNonNull(impl); // see the comment on the field
       checkNotNull(element);
       copyIfNecessary();
       impl = impl.add(element);
@@ -552,6 +557,16 @@ public Builder<E> addAll(Iterator<? extends E> elements) {
     }
 
     Builder<E> combine(Builder<E> other) {
+      requireNonNull(impl);
+      requireNonNull(other.impl);
+      /*
+       * For discussion of requireNonNull, see the comment on the field.
+       *
+       * (And I don't believe there's any situation in which we call x.combine(y) when x is a plain
+       * ImmutableSet.Builder but y is an ImmutableSortedSet.Builder (or vice versa). Certainly
+       * ImmutableSortedSet.Builder.combine() is written as if its argument will never be a plain
+       * ImmutableSet.Builder: It casts immediately to ImmutableSortedSet.Builder.)
+       */
       copyIfNecessary();
       this.impl = this.impl.combine(other.impl);
       return this;
@@ -559,6 +574,7 @@ Builder<E> combine(Builder<E> other) {
 
     @Override
     public ImmutableSet<E> build() {
+      requireNonNull(impl); // see the comment on the field
       forceCopy = true;
       impl = impl.review();
       return impl.build();
@@ -567,6 +583,8 @@ public ImmutableSet<E> build() {
 
   /** Swappable internal implementation of an ImmutableSet.Builder. */
   private abstract static class SetBuilderImpl<E> {
+    // The first `distinct` elements are non-null.
+    // Since we can never access null elements, we don't mark this nullable.
     E[] dedupedElements;
     int distinct;
 
@@ -610,7 +628,11 @@ final void addDedupedElement(E e) {
     final SetBuilderImpl<E> combine(SetBuilderImpl<E> other) {
       SetBuilderImpl<E> result = this;
       for (int i = 0; i < other.distinct; i++) {
-        result = result.add(other.dedupedElements[i]);
+        /*
+         * requireNonNull is safe because we ensure that the first `distinct` elements have been
+         * populated.
+         */
+        result = result.add(requireNonNull(other.dedupedElements[i]));
       }
       return result;
     }
@@ -632,6 +654,34 @@ SetBuilderImpl<E> review() {
     abstract ImmutableSet<E> build();
   }
 
+  private static final class EmptySetBuilderImpl<E> extends SetBuilderImpl<E> {
+    private static final EmptySetBuilderImpl<Object> INSTANCE = new EmptySetBuilderImpl<>();
+
+    @SuppressWarnings("unchecked")
+    static <E> SetBuilderImpl<E> instance() {
+      return (SetBuilderImpl<E>) INSTANCE;
+    }
+
+    private EmptySetBuilderImpl() {
+      super(0);
+    }
+
+    @Override
+    SetBuilderImpl<E> add(E e) {
+      return new RegularSetBuilderImpl<E>(Builder.DEFAULT_INITIAL_CAPACITY).add(e);
+    }
+
+    @Override
+    SetBuilderImpl<E> copy() {
+      return this;
+    }
+
+    @Override
+    ImmutableSet<E> build() {
+      return ImmutableSet.of();
+    }
+  }
+
   // We use power-of-2 tables, and this is the highest int that's a power of 2
   static final int MAX_TABLE_SIZE = Ints.MAX_POWER_OF_TWO;
 
@@ -647,7 +697,7 @@ SetBuilderImpl<E> review() {
    * with linear probing in its implementation. The returned size is the smallest power of two that
    * can hold setSize elements with the desired load factor. Always returns at least setSize + 2.
    */
-  @VisibleForTesting
+  // TODO(cpovirk): Move to Hashing or something, since it's used elsewhere in the Android version.
   static int chooseTableSize(int setSize) {
     setSize = Math.max(setSize, 2);
     // Correct the size for open addressing to match desired load factor.
@@ -665,92 +715,6 @@ static int chooseTableSize(int setSize) {
     return MAX_TABLE_SIZE;
   }
 
-  /**
-   * We attempt to detect deliberate hash flooding attempts, and if one is detected, fall back to a
-   * wrapper around j.u.HashSet, which has built in flooding protection. HASH_FLOODING_FPP is the
-   * maximum allowed probability of falsely detecting a hash flooding attack if the input is
-   * randomly generated.
-   *
-   * <p>MAX_RUN_MULTIPLIER was determined experimentally to match this FPP.
-   */
-  static final double HASH_FLOODING_FPP = 0.001;
-
-  // NB: yes, this is surprisingly high, but that's what the experiments said was necessary
-  // The higher it is, the worse constant factors we are willing to accept.
-  static final int MAX_RUN_MULTIPLIER = 13;
-
-  /**
-   * Checks the whole hash table for poor hash distribution. Takes O(n) in the worst case, O(n / log
-   * n) on average.
-   *
-   * <p>The online hash flooding detecting in RegularSetBuilderImpl.add can detect e.g. many exactly
-   * matching hash codes, which would cause construction to take O(n^2), but can't detect e.g. hash
-   * codes adversarially designed to go into ascending table locations, which keeps construction
-   * O(n) (as desired) but then can have O(n) queries later.
-   *
-   * <p>If this returns false, then no query can take more than O(log n).
-   *
-   * <p>Note that for a RegularImmutableSet with elements with truly random hash codes, contains
-   * operations take expected O(1) time but with high probability take O(log n) for at least some
-   * element. (https://en.wikipedia.org/wiki/Linear_probing#Analysis)
-   *
-   * <p>This method may return {@code true} up to {@link #HASH_FLOODING_FPP} of the time even on
-   * truly random input.
-   *
-   * <p>If this method returns false, there are definitely no runs of length at least {@code
-   * maxRunBeforeFallback(hashTable.length)} nonnull elements. If there are no runs of length at
-   * least {@code maxRunBeforeFallback(hashTable.length) / 2} nonnull elements, this method
-   * definitely returns false. In between those constraints, the result of this method is undefined,
-   * subject to the above {@link #HASH_FLOODING_FPP} constraint.
-   */
-  static boolean hashFloodingDetected(Object[] hashTable) {
-    int maxRunBeforeFallback = maxRunBeforeFallback(hashTable.length);
-
-    // Test for a run wrapping around the end of the table of length at least maxRunBeforeFallback.
-    int endOfStartRun;
-    for (endOfStartRun = 0; endOfStartRun < hashTable.length; ) {
-      if (hashTable[endOfStartRun] == null) {
-        break;
-      }
-      endOfStartRun++;
-      if (endOfStartRun > maxRunBeforeFallback) {
-        return true;
-      }
-    }
-    int startOfEndRun;
-    for (startOfEndRun = hashTable.length - 1; startOfEndRun > endOfStartRun; startOfEndRun--) {
-      if (hashTable[startOfEndRun] == null) {
-        break;
-      }
-      if (endOfStartRun + (hashTable.length - 1 - startOfEndRun) > maxRunBeforeFallback) {
-        return true;
-      }
-    }
-
-    // Now, break the remainder of the table into blocks of maxRunBeforeFallback/2 elements and
-    // check that each has at least one null.
-    int testBlockSize = maxRunBeforeFallback / 2;
-    blockLoop:
-    for (int i = endOfStartRun + 1; i + testBlockSize <= startOfEndRun; i += testBlockSize) {
-      for (int j = 0; j < testBlockSize; j++) {
-        if (hashTable[i + j] == null) {
-          continue blockLoop;
-        }
-      }
-      return true;
-    }
-    return false;
-  }
-
-  /**
-   * If more than this many consecutive positions are filled in a table of the specified size,
-   * report probable hash flooding. ({@link #hashFloodingDetected} may also report hash flooding if
-   * fewer consecutive positions are filled; see that method for details.)
-   */
-  private static int maxRunBeforeFallback(int tableSize) {
-    return MAX_RUN_MULTIPLIER * IntMath.log2(tableSize, RoundingMode.UNNECESSARY);
-  }
-
   /**
    * Default implementation of the guts of ImmutableSet.Builder, creating an open-addressed hash
    * table and deduplicating elements as they come, so it only allocates O(max(distinct,
@@ -760,39 +724,46 @@ private static int maxRunBeforeFallback(int tableSize) {
    * JdkBackedSetBuilderImpl.
    */
   private static final class RegularSetBuilderImpl<E> extends SetBuilderImpl<E> {
-    private Object[] hashTable;
+    // null until at least two elements are present
+    private @Nullable Object @Nullable [] hashTable;
     private int maxRunBeforeFallback;
     private int expandTableThreshold;
     private int hashCode;
 
     RegularSetBuilderImpl(int expectedCapacity) {
       super(expectedCapacity);
-      int tableSize = chooseTableSize(expectedCapacity);
-      this.hashTable = new Object[tableSize];
-      this.maxRunBeforeFallback = maxRunBeforeFallback(tableSize);
-      this.expandTableThreshold = (int) (DESIRED_LOAD_FACTOR * tableSize);
+      this.hashTable = null;
+      this.maxRunBeforeFallback = 0;
+      this.expandTableThreshold = 0;
     }
 
     RegularSetBuilderImpl(RegularSetBuilderImpl<E> toCopy) {
       super(toCopy);
-      this.hashTable = Arrays.copyOf(toCopy.hashTable, toCopy.hashTable.length);
+      this.hashTable = (toCopy.hashTable == null) ? null : toCopy.hashTable.clone();
       this.maxRunBeforeFallback = toCopy.maxRunBeforeFallback;
       this.expandTableThreshold = toCopy.expandTableThreshold;
       this.hashCode = toCopy.hashCode;
     }
 
-    void ensureTableCapacity(int minCapacity) {
-      if (minCapacity > expandTableThreshold && hashTable.length < MAX_TABLE_SIZE) {
-        int newTableSize = hashTable.length * 2;
-        hashTable = rebuildHashTable(newTableSize, dedupedElements, distinct);
-        maxRunBeforeFallback = maxRunBeforeFallback(newTableSize);
-        expandTableThreshold = (int) (DESIRED_LOAD_FACTOR * newTableSize);
-      }
-    }
-
     @Override
     SetBuilderImpl<E> add(E e) {
       checkNotNull(e);
+      if (hashTable == null) {
+        if (distinct == 0) {
+          addDedupedElement(e);
+          return this;
+        } else {
+          ensureTableCapacity(dedupedElements.length);
+          E elem = dedupedElements[0];
+          distinct--;
+          return insertInHashTable(elem).add(e);
+        }
+      }
+      return insertInHashTable(e);
+    }
+
+    private SetBuilderImpl<E> insertInHashTable(E e) {
+      requireNonNull(hashTable);
       int eHash = e.hashCode();
       int i0 = Hashing.smear(eHash);
       int mask = hashTable.length - 1;
@@ -820,6 +791,9 @@ SetBuilderImpl<E> copy() {
 
     @Override
     SetBuilderImpl<E> review() {
+      if (hashTable == null) {
+        return this;
+      }
       int targetTableSize = chooseTableSize(distinct);
       if (targetTableSize * 2 < hashTable.length) {
         hashTable = rebuildHashTable(targetTableSize, dedupedElements, distinct);
@@ -835,15 +809,134 @@ ImmutableSet<E> build() {
         case 0:
           return of();
         case 1:
-          return of(dedupedElements[0]);
+          /*
+           * requireNonNull is safe because we ensure that the first `distinct` elements have been
+           * populated.
+           */
+          return of(requireNonNull(dedupedElements[0]));
         default:
+          /*
+           * The suppression is safe because we ensure that the first `distinct` elements have been
+           * populated.
+           */
+          @SuppressWarnings("nullness")
           Object[] elements =
               (distinct == dedupedElements.length)
                   ? dedupedElements
                   : Arrays.copyOf(dedupedElements, distinct);
-          return new RegularImmutableSet<E>(elements, hashCode, hashTable, hashTable.length - 1);
+          return new RegularImmutableSet<E>(
+              elements, hashCode, requireNonNull(hashTable), hashTable.length - 1);
       }
     }
+
+    /** Builds a new open-addressed hash table from the first n objects in elements. */
+    static @Nullable Object[] rebuildHashTable(int newTableSize, Object[] elements, int n) {
+      @Nullable Object[] hashTable = new @Nullable Object[newTableSize];
+      int mask = hashTable.length - 1;
+      for (int i = 0; i < n; i++) {
+        // requireNonNull is safe because we ensure that the first n elements have been populated.
+        Object e = requireNonNull(elements[i]);
+        int j0 = Hashing.smear(e.hashCode());
+        for (int j = j0; ; j++) {
+          int index = j & mask;
+          if (hashTable[index] == null) {
+            hashTable[index] = e;
+            break;
+          }
+        }
+      }
+      return hashTable;
+    }
+
+    void ensureTableCapacity(int minCapacity) {
+      int newTableSize;
+      if (hashTable == null) {
+        newTableSize = chooseTableSize(minCapacity);
+        hashTable = new Object[newTableSize];
+      } else if (minCapacity > expandTableThreshold && hashTable.length < MAX_TABLE_SIZE) {
+        newTableSize = hashTable.length * 2;
+        hashTable = rebuildHashTable(newTableSize, dedupedElements, distinct);
+      } else {
+        return;
+      }
+      maxRunBeforeFallback = maxRunBeforeFallback(newTableSize);
+      expandTableThreshold = (int) (DESIRED_LOAD_FACTOR * newTableSize);
+    }
+
+    /**
+     * We attempt to detect deliberate hash flooding attempts. If one is detected, we fall back to a
+     * wrapper around j.u.HashSet, which has built in flooding protection. MAX_RUN_MULTIPLIER was
+     * determined experimentally to match our desired probability of false positives.
+     */
+    // NB: yes, this is surprisingly high, but that's what the experiments said was necessary
+    // Raising this number slows the worst-case contains behavior, speeds up hashFloodingDetected,
+    // and reduces the false-positive probability.
+    static final int MAX_RUN_MULTIPLIER = 13;
+
+    /**
+     * Checks the whole hash table for poor hash distribution. Takes O(n) in the worst case, O(n /
+     * log n) on average.
+     *
+     * <p>The online hash flooding detecting in RegularSetBuilderImpl.add can detect e.g. many
+     * exactly matching hash codes, which would cause construction to take O(n^2), but can't detect
+     * e.g. hash codes adversarially designed to go into ascending table locations, which keeps
+     * construction O(n) (as desired) but then can have O(n) queries later.
+     *
+     * <p>If this returns false, then no query can take more than O(log n).
+     *
+     * <p>Note that for a RegularImmutableSet with elements with truly random hash codes, contains
+     * operations take expected O(1) time but with high probability take O(log n) for at least some
+     * element. (https://en.wikipedia.org/wiki/Linear_probing#Analysis)
+     *
+     * <p>This method may return {@code true} even on truly random input, but {@code
+     * ImmutableSetTest} tests that the probability of that is low.
+     */
+    static boolean hashFloodingDetected(@Nullable Object[] hashTable) {
+      int maxRunBeforeFallback = maxRunBeforeFallback(hashTable.length);
+      int mask = hashTable.length - 1;
+
+      // Invariant: all elements at indices in [knownRunStart, knownRunEnd) are nonnull.
+      // If knownRunStart == knownRunEnd, this is vacuously true.
+      // When knownRunEnd exceeds hashTable.length, it "wraps", detecting runs around the end
+      // of the table.
+      int knownRunStart = 0;
+      int knownRunEnd = 0;
+
+      outerLoop:
+      while (knownRunStart < hashTable.length) {
+        if (knownRunStart == knownRunEnd && hashTable[knownRunStart] == null) {
+          if (hashTable[(knownRunStart + maxRunBeforeFallback - 1) & mask] == null) {
+            // There are only maxRunBeforeFallback - 1 elements between here and there,
+            // so even if they were all nonnull, we wouldn't detect a hash flood.  Therefore,
+            // we can skip them all.
+            knownRunStart += maxRunBeforeFallback;
+          } else {
+            knownRunStart++; // the only case in which maxRunEnd doesn't increase by mRBF
+            // happens about f * (1-f) for f = DESIRED_LOAD_FACTOR, so around 21% of the time
+          }
+          knownRunEnd = knownRunStart;
+        } else {
+          for (int j = knownRunStart + maxRunBeforeFallback - 1; j >= knownRunEnd; j--) {
+            if (hashTable[j & mask] == null) {
+              knownRunEnd = knownRunStart + maxRunBeforeFallback;
+              knownRunStart = j + 1;
+              continue outerLoop;
+            }
+          }
+          return true;
+        }
+      }
+      return false;
+    }
+
+    /**
+     * If more than this many consecutive positions are filled in a table of the specified size,
+     * report probable hash flooding. ({@link #hashFloodingDetected} may also report hash flooding
+     * if fewer consecutive positions are filled; see that method for details.)
+     */
+    static int maxRunBeforeFallback(int tableSize) {
+      return MAX_RUN_MULTIPLIER * IntMath.log2(tableSize, RoundingMode.UNNECESSARY);
+    }
   }
 
   /**
@@ -856,7 +949,11 @@ private static final class JdkBackedSetBuilderImpl<E> extends SetBuilderImpl<E>
       super(toCopy); // initializes dedupedElements and distinct
       delegate = Sets.newHashSetWithExpectedSize(distinct);
       for (int i = 0; i < distinct; i++) {
-        delegate.add(dedupedElements[i]);
+        /*
+         * requireNonNull is safe because we ensure that the first `distinct` elements have been
+         * populated.
+         */
+        delegate.add(requireNonNull(dedupedElements[i]));
       }
     }
 
@@ -880,7 +977,11 @@ ImmutableSet<E> build() {
         case 0:
           return of();
         case 1:
-          return of(dedupedElements[0]);
+          /*
+           * requireNonNull is safe because we ensure that the first `distinct` elements have been
+           * populated.
+           */
+          return of(requireNonNull(dedupedElements[0]));
         default:
           return new JdkBackedImmutableSet<E>(
               delegate, ImmutableList.asImmutableList(dedupedElements, distinct));
diff --git a/guava/src/com/google/common/collect/ImmutableSetMultimap.java b/guava/src/com/google/common/collect/ImmutableSetMultimap.java
index a155091f4cd5..e76767dc0b1f 100644
--- a/guava/src/com/google/common/collect/ImmutableSetMultimap.java
+++ b/guava/src/com/google/common/collect/ImmutableSetMultimap.java
@@ -39,6 +39,7 @@
 import java.util.function.Function;
 import java.util.stream.Collector;
 import java.util.stream.Stream;
+import javax.annotation.CheckForNull;
 import org.checkerframework.checker.nullness.qual.Nullable;
 import org.checkerframework.dataflow.qual.SideEffectFree;
 import org.checkerframework.framework.qual.AnnotatedFor;
@@ -47,14 +48,19 @@
  * A {@link SetMultimap} whose contents will never change, with many other important properties
  * detailed at {@link ImmutableCollection}.
  *
+ * <p><b>Warning:</b> As in all {@link SetMultimap}s, do not modify either a key <i>or a value</i>
+ * of a {@code ImmutableSetMultimap} in a way that affects its {@link Object#equals} behavior.
+ * Undefined behavior and bugs will result.
+ *
  * <p>See the Guava User Guide article on <a href=
- * "https://github.com/google/guava/wiki/ImmutableCollectionsExplained"> immutable collections</a>.
+ * "https://github.com/google/guava/wiki/ImmutableCollectionsExplained">immutable collections</a>.
  *
  * @author Mike Ward
  * @since 2.0
  */
 @AnnotatedFor({"nullness"})
 @GwtCompatible(serializable = true, emulated = true)
+@ElementTypesAreNonnullByDefault
 public class ImmutableSetMultimap<K, V> extends ImmutableMultimap<K, V>
     implements SetMultimap<K, V> {
   /**
@@ -85,9 +91,10 @@ public class ImmutableSetMultimap<K, V> extends ImmutableMultimap<K, V>
    *
    * @since 21.0
    */
-  public static <T, K, V> Collector<T, ?, ImmutableSetMultimap<K, V>> toImmutableSetMultimap(
-      Function<? super T, ? extends K> keyFunction,
-      Function<? super T, ? extends V> valueFunction) {
+  public static <T extends @Nullable Object, K, V>
+      Collector<T, ?, ImmutableSetMultimap<K, V>> toImmutableSetMultimap(
+          Function<? super T, ? extends K> keyFunction,
+          Function<? super T, ? extends V> valueFunction) {
     return CollectCollectors.toImmutableSetMultimap(keyFunction, valueFunction);
   }
 
@@ -131,14 +138,18 @@ public class ImmutableSetMultimap<K, V> extends ImmutableMultimap<K, V>
    *
    * @since 21.0
    */
-  public static <T, K, V>
+  public static <T extends @Nullable Object, K, V>
       Collector<T, ?, ImmutableSetMultimap<K, V>> flatteningToImmutableSetMultimap(
           Function<? super T, ? extends K> keyFunction,
           Function<? super T, ? extends Stream<? extends V>> valuesFunction) {
     return CollectCollectors.flatteningToImmutableSetMultimap(keyFunction, valuesFunction);
   }
 
-  /** Returns the empty multimap. */
+  /**
+   * Returns the empty multimap.
+   *
+   * <p><b>Performance note:</b> the instance returned is a singleton.
+   */
   // Casting is safe because the multimap will never hold any elements.
   @SuppressWarnings("unchecked")
   public static <K, V> ImmutableSetMultimap<K, V> of() {
@@ -366,7 +377,8 @@ public static <K, V> ImmutableSetMultimap<K, V> copyOf(
   }
 
   private static <K, V> ImmutableSetMultimap<K, V> copyOf(
-      Multimap<? extends K, ? extends V> multimap, Comparator<? super V> valueComparator) {
+      Multimap<? extends K, ? extends V> multimap,
+      @CheckForNull Comparator<? super V> valueComparator) {
     checkNotNull(multimap); // eager for GWT
     if (multimap.isEmpty() && valueComparator == null) {
       return of();
@@ -401,7 +413,7 @@ public static <K, V> ImmutableSetMultimap<K, V> copyOf(
   /** Creates an ImmutableSetMultimap from an asMap.entrySet. */
   static <K, V> ImmutableSetMultimap<K, V> fromMapEntries(
       Collection<? extends Map.Entry<? extends K, ? extends Collection<? extends V>>> mapEntries,
-      @Nullable Comparator<? super V> valueComparator) {
+      @CheckForNull Comparator<? super V> valueComparator) {
     if (mapEntries.isEmpty()) {
       return of();
     }
@@ -419,7 +431,7 @@ static <K, V> ImmutableSetMultimap<K, V> fromMapEntries(
       }
     }
 
-    return new ImmutableSetMultimap<>(builder.build(), size, valueComparator);
+    return new ImmutableSetMultimap<>(builder.buildOrThrow(), size, valueComparator);
   }
 
   /**
@@ -431,7 +443,7 @@ static <K, V> ImmutableSetMultimap<K, V> fromMapEntries(
   ImmutableSetMultimap(
       ImmutableMap<K, ImmutableSet<V>> map,
       int size,
-      @Nullable Comparator<? super V> valueComparator) {
+      @CheckForNull Comparator<? super V> valueComparator) {
     super(map, size);
     this.emptySet = emptySet(valueComparator);
   }
@@ -444,13 +456,13 @@ static <K, V> ImmutableSetMultimap<K, V> fromMapEntries(
    * parameters used to build this multimap.
    */
   @Override
-  public ImmutableSet<V> get(@Nullable K key) {
+  public ImmutableSet<V> get(K key) {
     // This cast is safe as its type is known in constructor.
     @Nullable ImmutableSet<V> set = (@Nullable ImmutableSet<V>) map.get(key);
     return MoreObjects.firstNonNull(set, emptySet);
   }
 
-  @LazyInit @RetainedWith private transient @Nullable ImmutableSetMultimap<V, K> inverse;
+  @LazyInit @RetainedWith @CheckForNull private transient ImmutableSetMultimap<V, K> inverse;
 
   /**
    * {@inheritDoc}
@@ -485,7 +497,7 @@ private ImmutableSetMultimap<V, K> invert() {
   @Deprecated
   @Override
   @DoNotCall("Always throws UnsupportedOperationException")
-  public final ImmutableSet<V> removeAll(@Nullable Object key) {
+  public final ImmutableSet<V> removeAll(@CheckForNull Object key) {
     throw new UnsupportedOperationException();
   }
 
@@ -503,7 +515,7 @@ public final ImmutableSet<V> replaceValues(K key, Iterable<? extends V> values)
     throw new UnsupportedOperationException();
   }
 
-  @LazyInit @RetainedWith private transient @Nullable ImmutableSet<Entry<K, V>> entries;
+  @LazyInit @RetainedWith @CheckForNull private transient ImmutableSet<Entry<K, V>> entries;
 
   /**
    * Returns an immutable collection of all key-value pairs in the multimap. Its iterator traverses
@@ -524,7 +536,7 @@ private static final class EntrySet<K, V> extends ImmutableSet<Entry<K, V>> {
     }
 
     @Override
-    public boolean contains(@Nullable Object object) {
+    public boolean contains(@CheckForNull Object object) {
       if (object instanceof Entry) {
         Entry<?, ?> entry = (Entry<?, ?>) object;
         return multimap.containsEntry(entry.getKey(), entry.getValue());
@@ -549,20 +561,20 @@ boolean isPartialView() {
   }
 
   private static <V> ImmutableSet<V> valueSet(
-      @Nullable Comparator<? super V> valueComparator, Collection<? extends V> values) {
+      @CheckForNull Comparator<? super V> valueComparator, Collection<? extends V> values) {
     return (valueComparator == null)
         ? ImmutableSet.copyOf(values)
         : ImmutableSortedSet.copyOf(valueComparator, values);
   }
 
-  private static <V> ImmutableSet<V> emptySet(@Nullable Comparator<? super V> valueComparator) {
+  private static <V> ImmutableSet<V> emptySet(@CheckForNull Comparator<? super V> valueComparator) {
     return (valueComparator == null)
         ? ImmutableSet.<V>of()
         : ImmutableSortedSet.<V>emptySet(valueComparator);
   }
 
   private static <V> ImmutableSet.Builder<V> valuesBuilder(
-      @Nullable Comparator<? super V> valueComparator) {
+      @CheckForNull Comparator<? super V> valueComparator) {
     return (valueComparator == null)
         ? new ImmutableSet.Builder<V>()
         : new ImmutableSortedSet.Builder<V>(valueComparator);
@@ -579,7 +591,7 @@ private void writeObject(ObjectOutputStream stream) throws IOException {
     Serialization.writeMultimap(this, stream);
   }
 
-  @Nullable
+  @CheckForNull
   Comparator<? super V> valueComparator() {
     return emptySet instanceof ImmutableSortedSet
         ? ((ImmutableSortedSet<V>) emptySet).comparator()
@@ -626,7 +638,7 @@ private void readObject(ObjectInputStream stream) throws IOException, ClassNotFo
 
     ImmutableMap<Object, ImmutableSet<Object>> tmpMap;
     try {
-      tmpMap = builder.build();
+      tmpMap = builder.buildOrThrow();
     } catch (IllegalArgumentException e) {
       throw (InvalidObjectException) new InvalidObjectException(e.getMessage()).initCause(e);
     }
diff --git a/guava/src/com/google/common/collect/ImmutableSortedAsList.java b/guava/src/com/google/common/collect/ImmutableSortedAsList.java
index 91f700ece687..ba11b193932f 100644
--- a/guava/src/com/google/common/collect/ImmutableSortedAsList.java
+++ b/guava/src/com/google/common/collect/ImmutableSortedAsList.java
@@ -18,7 +18,7 @@
 import com.google.common.annotations.GwtIncompatible;
 import java.util.Comparator;
 import java.util.Spliterator;
-import org.checkerframework.checker.nullness.qual.Nullable;
+import javax.annotation.CheckForNull;
 
 /**
  * List returned by {@code ImmutableSortedSet.asList()} when the set isn't empty.
@@ -28,6 +28,7 @@
  */
 @GwtCompatible(emulated = true)
 @SuppressWarnings("serial")
+@ElementTypesAreNonnullByDefault
 final class ImmutableSortedAsList<E> extends RegularImmutableAsList<E>
     implements SortedIterable<E> {
   ImmutableSortedAsList(ImmutableSortedSet<E> backingSet, ImmutableList<E> backingList) {
@@ -49,7 +50,7 @@ public Comparator<? super E> comparator() {
   @GwtIncompatible // ImmutableSortedSet.indexOf
   // TODO(cpovirk): consider manual binary search under GWT to preserve O(log N) lookup
   @Override
-  public int indexOf(@Nullable Object target) {
+  public int indexOf(@CheckForNull Object target) {
     int index = delegateCollection().indexOf(target);
 
     // TODO(kevinb): reconsider if it's really worth making feeble attempts at
@@ -62,12 +63,12 @@ public int indexOf(@Nullable Object target) {
 
   @GwtIncompatible // ImmutableSortedSet.indexOf
   @Override
-  public int lastIndexOf(@Nullable Object target) {
+  public int lastIndexOf(@CheckForNull Object target) {
     return indexOf(target);
   }
 
   @Override
-  public boolean contains(Object target) {
+  public boolean contains(@CheckForNull Object target) {
     // Necessary for ISS's with comparators inconsistent with equals.
     return indexOf(target) >= 0;
   }
@@ -85,6 +86,7 @@ ImmutableList<E> subListUnchecked(int fromIndex, int toIndex) {
   }
 
   @Override
+  @SuppressWarnings("value:methodref.param")
   public Spliterator<E> spliterator() {
     return CollectSpliterators.indexed(
         size(),
diff --git a/guava/src/com/google/common/collect/ImmutableSortedMap.java b/guava/src/com/google/common/collect/ImmutableSortedMap.java
index f4dd32a53b9b..1985f78d4c71 100644
--- a/guava/src/com/google/common/collect/ImmutableSortedMap.java
+++ b/guava/src/com/google/common/collect/ImmutableSortedMap.java
@@ -20,6 +20,7 @@
 import static com.google.common.base.Preconditions.checkNotNull;
 import static com.google.common.collect.CollectPreconditions.checkEntryNotNull;
 import static com.google.common.collect.Maps.keyOrNull;
+import static java.util.Objects.requireNonNull;
 
 import com.google.common.annotations.Beta;
 import com.google.common.annotations.GwtCompatible;
@@ -39,6 +40,7 @@
 import java.util.function.Function;
 import java.util.stream.Collector;
 import java.util.stream.Collectors;
+import javax.annotation.CheckForNull;
 import org.checkerframework.checker.nullness.qual.Nullable;
 import org.checkerframework.dataflow.qual.Pure;
 import org.checkerframework.dataflow.qual.SideEffectFree;
@@ -55,7 +57,7 @@
  * not correctly obey its specification.
  *
  * <p>See the Guava User Guide article on <a href=
- * "https://github.com/google/guava/wiki/ImmutableCollectionsExplained"> immutable collections</a>.
+ * "https://github.com/google/guava/wiki/ImmutableCollectionsExplained">immutable collections</a>.
  *
  * @author Jared Levy
  * @author Louis Wasserman
@@ -63,6 +65,7 @@
  */
 @AnnotatedFor({"nullness"})
 @GwtCompatible(serializable = true, emulated = true)
+@ElementTypesAreNonnullByDefault
 public final class ImmutableSortedMap<K, V> extends ImmutableSortedMapFauxverideShim<K, V>
     implements NavigableMap<K, V> {
   /**
@@ -77,10 +80,11 @@ public final class ImmutableSortedMap<K, V> extends ImmutableSortedMapFauxveride
    *
    * @since 21.0
    */
-  public static <T, K, V> Collector<T, ?, ImmutableSortedMap<K, V>> toImmutableSortedMap(
-      Comparator<? super K> comparator,
-      Function<? super T, ? extends K> keyFunction,
-      Function<? super T, ? extends V> valueFunction) {
+  public static <T extends @Nullable Object, K, V>
+      Collector<T, ?, ImmutableSortedMap<K, V>> toImmutableSortedMap(
+          Comparator<? super K> comparator,
+          Function<? super T, ? extends K> keyFunction,
+          Function<? super T, ? extends V> valueFunction) {
     return CollectCollectors.toImmutableSortedMap(comparator, keyFunction, valueFunction);
   }
 
@@ -95,11 +99,12 @@ public final class ImmutableSortedMap<K, V> extends ImmutableSortedMapFauxveride
    *
    * @since 21.0
    */
-  public static <T, K, V> Collector<T, ?, ImmutableSortedMap<K, V>> toImmutableSortedMap(
-      Comparator<? super K> comparator,
-      Function<? super T, ? extends K> keyFunction,
-      Function<? super T, ? extends V> valueFunction,
-      BinaryOperator<V> mergeFunction) {
+  public static <T extends @Nullable Object, K, V>
+      Collector<T, ?, ImmutableSortedMap<K, V>> toImmutableSortedMap(
+          Comparator<? super K> comparator,
+          Function<? super T, ? extends K> keyFunction,
+          Function<? super T, ? extends V> valueFunction,
+          BinaryOperator<V> mergeFunction) {
     return CollectCollectors.toImmutableSortedMap(
         comparator, keyFunction, valueFunction, mergeFunction);
   }
@@ -123,7 +128,11 @@ static <K, V> ImmutableSortedMap<K, V> emptyMap(Comparator<? super K> comparator
     }
   }
 
-  /** Returns the empty sorted map. */
+  /**
+   * Returns the empty sorted map.
+   *
+   * <p><b>Performance note:</b> the instance returned is a singleton.
+   */
   @SuppressWarnings("unchecked")
   // unsafe, comparator() returns a comparator on the specified type
   // TODO(kevinb): evaluate whether or not of().comparator() should return null
@@ -152,7 +161,7 @@ private static <K, V> ImmutableSortedMap<K, V> of(Comparator<? super K> comparat
   @SuppressWarnings("unchecked")
   public static <K extends Comparable<? super K>, V> ImmutableSortedMap<K, V> of(
       K k1, V v1, K k2, V v2) {
-    return ofEntries(entryOf(k1, v1), entryOf(k2, v2));
+    return fromEntries(entryOf(k1, v1), entryOf(k2, v2));
   }
 
   /**
@@ -164,7 +173,7 @@ public static <K extends Comparable<? super K>, V> ImmutableSortedMap<K, V> of(
   @SuppressWarnings("unchecked")
   public static <K extends Comparable<? super K>, V> ImmutableSortedMap<K, V> of(
       K k1, V v1, K k2, V v2, K k3, V v3) {
-    return ofEntries(entryOf(k1, v1), entryOf(k2, v2), entryOf(k3, v3));
+    return fromEntries(entryOf(k1, v1), entryOf(k2, v2), entryOf(k3, v3));
   }
 
   /**
@@ -176,7 +185,7 @@ public static <K extends Comparable<? super K>, V> ImmutableSortedMap<K, V> of(
   @SuppressWarnings("unchecked")
   public static <K extends Comparable<? super K>, V> ImmutableSortedMap<K, V> of(
       K k1, V v1, K k2, V v2, K k3, V v3, K k4, V v4) {
-    return ofEntries(entryOf(k1, v1), entryOf(k2, v2), entryOf(k3, v3), entryOf(k4, v4));
+    return fromEntries(entryOf(k1, v1), entryOf(k2, v2), entryOf(k3, v3), entryOf(k4, v4));
   }
 
   /**
@@ -188,13 +197,164 @@ public static <K extends Comparable<? super K>, V> ImmutableSortedMap<K, V> of(
   @SuppressWarnings("unchecked")
   public static <K extends Comparable<? super K>, V> ImmutableSortedMap<K, V> of(
       K k1, V v1, K k2, V v2, K k3, V v3, K k4, V v4, K k5, V v5) {
-    return ofEntries(
+    return fromEntries(
         entryOf(k1, v1), entryOf(k2, v2), entryOf(k3, v3), entryOf(k4, v4), entryOf(k5, v5));
   }
 
-  private static <K extends Comparable<? super K>, V> ImmutableSortedMap<K, V> ofEntries(
-      Entry<K, V>... entries) {
-    return fromEntries(Ordering.natural(), false, entries, entries.length);
+  /**
+   * Returns an immutable sorted map containing the given entries, sorted by the natural ordering of
+   * their keys.
+   *
+   * @throws IllegalArgumentException if any two keys are equal according to their natural ordering
+   * @since 31.0
+   */
+  @SuppressWarnings("unchecked")
+  public static <K extends Comparable<? super K>, V> ImmutableSortedMap<K, V> of(
+      K k1, V v1, K k2, V v2, K k3, V v3, K k4, V v4, K k5, V v5, K k6, V v6) {
+    return fromEntries(
+        entryOf(k1, v1),
+        entryOf(k2, v2),
+        entryOf(k3, v3),
+        entryOf(k4, v4),
+        entryOf(k5, v5),
+        entryOf(k6, v6));
+  }
+
+  /**
+   * Returns an immutable sorted map containing the given entries, sorted by the natural ordering of
+   * their keys.
+   *
+   * @throws IllegalArgumentException if any two keys are equal according to their natural ordering
+   * @since 31.0
+   */
+  @SuppressWarnings("unchecked")
+  public static <K extends Comparable<? super K>, V> ImmutableSortedMap<K, V> of(
+      K k1, V v1, K k2, V v2, K k3, V v3, K k4, V v4, K k5, V v5, K k6, V v6, K k7, V v7) {
+    return fromEntries(
+        entryOf(k1, v1),
+        entryOf(k2, v2),
+        entryOf(k3, v3),
+        entryOf(k4, v4),
+        entryOf(k5, v5),
+        entryOf(k6, v6),
+        entryOf(k7, v7));
+  }
+
+  /**
+   * Returns an immutable sorted map containing the given entries, sorted by the natural ordering of
+   * their keys.
+   *
+   * @throws IllegalArgumentException if any two keys are equal according to their natural ordering
+   * @since 31.0
+   */
+  @SuppressWarnings("unchecked")
+  public static <K extends Comparable<? super K>, V> ImmutableSortedMap<K, V> of(
+      K k1,
+      V v1,
+      K k2,
+      V v2,
+      K k3,
+      V v3,
+      K k4,
+      V v4,
+      K k5,
+      V v5,
+      K k6,
+      V v6,
+      K k7,
+      V v7,
+      K k8,
+      V v8) {
+    return fromEntries(
+        entryOf(k1, v1),
+        entryOf(k2, v2),
+        entryOf(k3, v3),
+        entryOf(k4, v4),
+        entryOf(k5, v5),
+        entryOf(k6, v6),
+        entryOf(k7, v7),
+        entryOf(k8, v8));
+  }
+
+  /**
+   * Returns an immutable sorted map containing the given entries, sorted by the natural ordering of
+   * their keys.
+   *
+   * @throws IllegalArgumentException if any two keys are equal according to their natural ordering
+   * @since 31.0
+   */
+  @SuppressWarnings("unchecked")
+  public static <K extends Comparable<? super K>, V> ImmutableSortedMap<K, V> of(
+      K k1,
+      V v1,
+      K k2,
+      V v2,
+      K k3,
+      V v3,
+      K k4,
+      V v4,
+      K k5,
+      V v5,
+      K k6,
+      V v6,
+      K k7,
+      V v7,
+      K k8,
+      V v8,
+      K k9,
+      V v9) {
+    return fromEntries(
+        entryOf(k1, v1),
+        entryOf(k2, v2),
+        entryOf(k3, v3),
+        entryOf(k4, v4),
+        entryOf(k5, v5),
+        entryOf(k6, v6),
+        entryOf(k7, v7),
+        entryOf(k8, v8),
+        entryOf(k9, v9));
+  }
+
+  /**
+   * Returns an immutable sorted map containing the given entries, sorted by the natural ordering of
+   * their keys.
+   *
+   * @throws IllegalArgumentException if any two keys are equal according to their natural ordering
+   * @since 31.0
+   */
+  @SuppressWarnings("unchecked")
+  public static <K extends Comparable<? super K>, V> ImmutableSortedMap<K, V> of(
+      K k1,
+      V v1,
+      K k2,
+      V v2,
+      K k3,
+      V v3,
+      K k4,
+      V v4,
+      K k5,
+      V v5,
+      K k6,
+      V v6,
+      K k7,
+      V v7,
+      K k8,
+      V v8,
+      K k9,
+      V v9,
+      K k10,
+      V v10) {
+    return fromEntries(
+        entryOf(k1, v1),
+        entryOf(k2, v2),
+        entryOf(k3, v3),
+        entryOf(k4, v4),
+        entryOf(k5, v5),
+        entryOf(k6, v6),
+        entryOf(k7, v7),
+        entryOf(k8, v8),
+        entryOf(k9, v9),
+        entryOf(k10, v10));
   }
 
   /**
@@ -324,6 +484,11 @@ private static <K, V> ImmutableSortedMap<K, V> copyOfInternal(
     return fromEntries(comparator, sameComparator, map.entrySet());
   }
 
+  private static <K extends Comparable<? super K>, V> ImmutableSortedMap<K, V> fromEntries(
+      Entry<K, V>... entries) {
+    return fromEntries(Ordering.natural(), false, entries, entries.length);
+  }
+
   /**
    * Accepts a collection of possibly-null entries. If {@code sameComparator}, then it is assumed
    * that they do not need to be sorted or checked for dupes.
@@ -343,22 +508,25 @@ private static <K, V> ImmutableSortedMap<K, V> fromEntries(
   private static <K, V> ImmutableSortedMap<K, V> fromEntries(
       final Comparator<? super K> comparator,
       boolean sameComparator,
-      Entry<K, V>[] entryArray,
+      @Nullable Entry<K, V>[] entryArray,
       int size) {
     switch (size) {
       case 0:
         return emptyMap(comparator);
       case 1:
-        return ImmutableSortedMap.<K, V>of(
-            comparator, entryArray[0].getKey(), entryArray[0].getValue());
+        // requireNonNull is safe because the first `size` elements have been filled in.
+        Entry<K, V> onlyEntry = requireNonNull(entryArray[0]);
+        return of(comparator, onlyEntry.getKey(), onlyEntry.getValue());
       default:
         Object[] keys = new Object[size];
         Object[] values = new Object[size];
         if (sameComparator) {
           // Need to check for nulls, but don't need to sort or validate.
           for (int i = 0; i < size; i++) {
-            Object key = entryArray[i].getKey();
-            Object value = entryArray[i].getValue();
+            // requireNonNull is safe because the first `size` elements have been filled in.
+            Entry<K, V> entry = requireNonNull(entryArray[i]);
+            Object key = entry.getKey();
+            Object value = entry.getValue();
             checkEntryNotNull(key, value);
             keys[i] = key;
             values[i] = value;
@@ -371,24 +539,31 @@ private static <K, V> ImmutableSortedMap<K, V> fromEntries(
               entryArray,
               0,
               size,
-              new Comparator<Entry<K, V>>() {
+              new Comparator<@Nullable Entry<K, V>>() {
                 @Override
-                public int compare(Entry<K, V> e1, Entry<K, V> e2) {
+                public int compare(@CheckForNull Entry<K, V> e1, @CheckForNull Entry<K, V> e2) {
+                  // requireNonNull is safe because the first `size` elements have been filled in.
+                  requireNonNull(e1);
+                  requireNonNull(e2);
                   return comparator.compare(e1.getKey(), e2.getKey());
                 }
               });
-          K prevKey = entryArray[0].getKey();
+          // requireNonNull is safe because the first `size` elements have been filled in.
+          Entry<K, V> firstEntry = requireNonNull(entryArray[0]);
+          K prevKey = firstEntry.getKey();
           keys[0] = prevKey;
-          values[0] = entryArray[0].getValue();
+          values[0] = firstEntry.getValue();
           checkEntryNotNull(keys[0], values[0]);
           for (int i = 1; i < size; i++) {
-            K key = entryArray[i].getKey();
-            V value = entryArray[i].getValue();
+            // requireNonNull is safe because the first `size` elements have been filled in.
+            Entry<K, V> prevEntry = requireNonNull(entryArray[i - 1]);
+            Entry<K, V> entry = requireNonNull(entryArray[i]);
+            K key = entry.getKey();
+            V value = entry.getValue();
             checkEntryNotNull(key, value);
             keys[i] = key;
             values[i] = value;
-            checkNoConflict(
-                comparator.compare(prevKey, key) != 0, "key", entryArray[i - 1], entryArray[i]);
+            checkNoConflict(comparator.compare(prevKey, key) != 0, "key", prevEntry, entry);
             prevKey = key;
           }
         }
@@ -436,14 +611,14 @@ public static <K extends Comparable<?>, V> Builder<K, V> reverseOrder() {
    *         .put(1, "one")
    *         .put(2, "two")
    *         .put(3, "three")
-   *         .build();
+   *         .buildOrThrow();
    * }</pre>
    *
    * <p>For <i>small</i> immutable sorted maps, the {@code ImmutableSortedMap.of()} methods are even
    * more convenient.
    *
-   * <p>Builder instances can be reused - it is safe to call {@link #build} multiple times to build
-   * multiple maps in series. Each map is a superset of the maps created before it.
+   * <p>Builder instances can be reused - it is safe to call {@link #buildOrThrow} multiple times to
+   * build multiple maps in series. Each map is a superset of the maps created before it.
    *
    * @since 2.0
    */
@@ -539,25 +714,62 @@ Builder<K, V> combine(ImmutableMap.Builder<K, V> other) {
     /**
      * Returns a newly-created immutable sorted map.
      *
+     * <p>Prefer the equivalent method {@link #buildOrThrow()} to make it explicit that the method
+     * will throw an exception if there are duplicate keys. The {@code build()} method will soon be
+     * deprecated.
+     *
      * @throws IllegalArgumentException if any two keys are equal according to the comparator (which
      *     might be the keys' natural order)
      */
     @Override
     public ImmutableSortedMap<K, V> build() {
+      return buildOrThrow();
+    }
+
+    /**
+     * Returns a newly-created immutable sorted map, or throws an exception if any two keys are
+     * equal.
+     *
+     * @throws IllegalArgumentException if any two keys are equal according to the comparator (which
+     *     might be the keys' natural order)
+     * @since 31.0
+     */
+    @Override
+    public ImmutableSortedMap<K, V> buildOrThrow() {
       switch (size) {
         case 0:
           return emptyMap(comparator);
         case 1:
-          return of(comparator, entries[0].getKey(), entries[0].getValue());
+          // requireNonNull is safe because the first `size` elements have been filled in.
+          Entry<K, V> onlyEntry = requireNonNull(entries[0]);
+          return of(comparator, onlyEntry.getKey(), onlyEntry.getValue());
         default:
           return fromEntries(comparator, false, entries, size);
       }
     }
+
+    /**
+     * Throws UnsupportedOperationException. A future version may support this operation. Then the
+     * value for any given key will be the one that was last supplied in a {@code put} operation for
+     * that key.
+     *
+     * @throws UnsupportedOperationException always
+     * @since 31.1
+     * @deprecated This method is not currently implemented, and may never be.
+     */
+    @DoNotCall
+    @Deprecated
+    @Override
+    public final ImmutableSortedMap<K, V> buildKeepingLast() {
+      // TODO(emcmanus): implement
+      throw new UnsupportedOperationException(
+          "ImmutableSortedMap.Builder does not yet implement buildKeepingLast()");
+    }
   }
 
   private final transient RegularImmutableSortedSet<K> keySet;
   private final transient ImmutableList<V> valueList;
-  private transient ImmutableSortedMap<K, V> descendingMap;
+  @CheckForNull private transient ImmutableSortedMap<K, V> descendingMap;
 
   ImmutableSortedMap(RegularImmutableSortedSet<K> keySet, ImmutableList<V> valueList) {
     this(keySet, valueList, null);
@@ -566,7 +778,7 @@ public ImmutableSortedMap<K, V> build() {
   ImmutableSortedMap(
       RegularImmutableSortedSet<K> keySet,
       ImmutableList<V> valueList,
-      ImmutableSortedMap<K, V> descendingMap) {
+      @CheckForNull ImmutableSortedMap<K, V> descendingMap) {
     this.keySet = keySet;
     this.valueList = valueList;
     this.descendingMap = descendingMap;
@@ -588,7 +800,8 @@ public void forEach(BiConsumer<? super K, ? super V> action) {
   }
 
   @Override
-  public @Nullable V get(@Nullable Object key) {
+  @CheckForNull
+  public V get(@CheckForNull Object key) {
     int index = keySet.indexOf(key);
     return (index == -1) ? null : valueList.get(index);
   }
@@ -818,51 +1031,61 @@ public ImmutableSortedMap<K, V> tailMap(K fromKey, boolean inclusive) {
   }
 
   @Override
+  @CheckForNull
   public Entry<K, V> lowerEntry(K key) {
     return headMap(key, false).lastEntry();
   }
 
   @Override
+  @CheckForNull
   public K lowerKey(K key) {
     return keyOrNull(lowerEntry(key));
   }
 
   @Override
+  @CheckForNull
   public Entry<K, V> floorEntry(K key) {
     return headMap(key, true).lastEntry();
   }
 
   @Override
+  @CheckForNull
   public K floorKey(K key) {
     return keyOrNull(floorEntry(key));
   }
 
   @Override
+  @CheckForNull
   public Entry<K, V> ceilingEntry(K key) {
     return tailMap(key, true).firstEntry();
   }
 
   @Override
+  @CheckForNull
   public K ceilingKey(K key) {
     return keyOrNull(ceilingEntry(key));
   }
 
   @Override
+  @CheckForNull
   public Entry<K, V> higherEntry(K key) {
     return tailMap(key, false).firstEntry();
   }
 
   @Override
+  @CheckForNull
   public K higherKey(K key) {
     return keyOrNull(higherEntry(key));
   }
 
   @Override
+  @CheckForNull
   public Entry<K, V> firstEntry() {
     return isEmpty() ? null : entrySet().asList().get(0);
   }
 
   @Override
+  @CheckForNull
   public Entry<K, V> lastEntry() {
     return isEmpty() ? null : entrySet().asList().get(size() - 1);
   }
@@ -877,6 +1100,7 @@ public Entry<K, V> lastEntry() {
   @Deprecated
   @Override
   @DoNotCall("Always throws UnsupportedOperationException")
+  @CheckForNull
   public final Entry<K, V> pollFirstEntry() {
     throw new UnsupportedOperationException();
   }
@@ -891,6 +1115,7 @@ public final Entry<K, V> pollFirstEntry() {
   @Deprecated
   @Override
   @DoNotCall("Always throws UnsupportedOperationException")
+  @CheckForNull
   public final Entry<K, V> pollLastEntry() {
     throw new UnsupportedOperationException();
   }
diff --git a/guava/src/com/google/common/collect/ImmutableSortedMapFauxverideShim.java b/guava/src/com/google/common/collect/ImmutableSortedMapFauxverideShim.java
index 87b83519e1ce..7b2e4d7552ec 100644
--- a/guava/src/com/google/common/collect/ImmutableSortedMapFauxverideShim.java
+++ b/guava/src/com/google/common/collect/ImmutableSortedMapFauxverideShim.java
@@ -17,9 +17,11 @@
 package com.google.common.collect;
 
 import com.google.common.annotations.GwtIncompatible;
+import com.google.errorprone.annotations.DoNotCall;
 import java.util.function.BinaryOperator;
 import java.util.function.Function;
 import java.util.stream.Collector;
+import org.checkerframework.checker.nullness.qual.Nullable;
 
 /**
  * "Overrides" the {@link ImmutableMap} static methods that lack {@link ImmutableSortedMap}
@@ -29,6 +31,7 @@
  * @author Chris Povirk
  */
 @GwtIncompatible
+@ElementTypesAreNonnullByDefault
 abstract class ImmutableSortedMapFauxverideShim<K, V> extends ImmutableMap<K, V> {
   /**
    * Not supported. Use {@link ImmutableSortedMap#toImmutableSortedMap}, which offers better
@@ -38,10 +41,12 @@ abstract class ImmutableSortedMapFauxverideShim<K, V> extends ImmutableMap<K, V>
    * @throws UnsupportedOperationException always
    * @deprecated Use {@link ImmutableSortedMap#toImmutableSortedMap}.
    */
+  @DoNotCall("Use toImmutableSortedMap")
   @Deprecated
-  public static <T, K, V> Collector<T, ?, ImmutableMap<K, V>> toImmutableMap(
-      Function<? super T, ? extends K> keyFunction,
-      Function<? super T, ? extends V> valueFunction) {
+  public static <T extends @Nullable Object, K, V>
+      Collector<T, ?, ImmutableMap<K, V>> toImmutableMap(
+          Function<? super T, ? extends K> keyFunction,
+          Function<? super T, ? extends V> valueFunction) {
     throw new UnsupportedOperationException();
   }
 
@@ -53,11 +58,13 @@ abstract class ImmutableSortedMapFauxverideShim<K, V> extends ImmutableMap<K, V>
    * @throws UnsupportedOperationException always
    * @deprecated Use {@link ImmutableSortedMap#toImmutableSortedMap}.
    */
+  @DoNotCall("Use toImmutableSortedMap")
   @Deprecated
-  public static <T, K, V> Collector<T, ?, ImmutableMap<K, V>> toImmutableMap(
-      Function<? super T, ? extends K> keyFunction,
-      Function<? super T, ? extends V> valueFunction,
-      BinaryOperator<V> mergeFunction) {
+  public static <T extends @Nullable Object, K, V>
+      Collector<T, ?, ImmutableMap<K, V>> toImmutableMap(
+          Function<? super T, ? extends K> keyFunction,
+          Function<? super T, ? extends V> valueFunction,
+          BinaryOperator<V> mergeFunction) {
     throw new UnsupportedOperationException();
   }
 
@@ -69,6 +76,7 @@ abstract class ImmutableSortedMapFauxverideShim<K, V> extends ImmutableMap<K, V>
    * @throws UnsupportedOperationException always
    * @deprecated Use {@link ImmutableSortedMap#naturalOrder}, which offers better type-safety.
    */
+  @DoNotCall("Use naturalOrder")
   @Deprecated
   public static <K, V> ImmutableSortedMap.Builder<K, V> builder() {
     throw new UnsupportedOperationException();
@@ -80,6 +88,7 @@ public static <K, V> ImmutableSortedMap.Builder<K, V> builder() {
    * @throws UnsupportedOperationException always
    * @deprecated Not supported for ImmutableSortedMap.
    */
+  @DoNotCall("Use naturalOrder (which does not accept an expected size)")
   @Deprecated
   public static <K, V> ImmutableSortedMap.Builder<K, V> builderWithExpectedSize(int expectedSize) {
     throw new UnsupportedOperationException();
@@ -94,6 +103,7 @@ public static <K, V> ImmutableSortedMap.Builder<K, V> builderWithExpectedSize(in
    * @deprecated <b>Pass a key of type {@code Comparable} to use {@link
    *     ImmutableSortedMap#of(Comparable, Object)}.</b>
    */
+  @DoNotCall("Pass a key of type Comparable")
   @Deprecated
   public static <K, V> ImmutableSortedMap<K, V> of(K k1, V v1) {
     throw new UnsupportedOperationException();
@@ -108,6 +118,7 @@ public static <K, V> ImmutableSortedMap<K, V> of(K k1, V v1) {
    * @deprecated <b>Pass keys of type {@code Comparable} to use {@link
    *     ImmutableSortedMap#of(Comparable, Object, Comparable, Object)}.</b>
    */
+  @DoNotCall("Pass keys of type Comparable")
   @Deprecated
   public static <K, V> ImmutableSortedMap<K, V> of(K k1, V v1, K k2, V v2) {
     throw new UnsupportedOperationException();
@@ -122,6 +133,7 @@ public static <K, V> ImmutableSortedMap<K, V> of(K k1, V v1, K k2, V v2) {
    * @deprecated <b>Pass keys of type {@code Comparable} to use {@link
    *     ImmutableSortedMap#of(Comparable, Object, Comparable, Object, Comparable, Object)}.</b>
    */
+  @DoNotCall("Pass keys of type Comparable")
   @Deprecated
   public static <K, V> ImmutableSortedMap<K, V> of(K k1, V v1, K k2, V v2, K k3, V v3) {
     throw new UnsupportedOperationException();
@@ -137,6 +149,7 @@ public static <K, V> ImmutableSortedMap<K, V> of(K k1, V v1, K k2, V v2, K k3, V
    *     ImmutableSortedMap#of(Comparable, Object, Comparable, Object, Comparable, Object,
    *     Comparable, Object)}.</b>
    */
+  @DoNotCall("Pass keys of type Comparable")
   @Deprecated
   public static <K, V> ImmutableSortedMap<K, V> of(K k1, V v1, K k2, V v2, K k3, V v3, K k4, V v4) {
     throw new UnsupportedOperationException();
@@ -152,11 +165,160 @@ public static <K, V> ImmutableSortedMap<K, V> of(K k1, V v1, K k2, V v2, K k3, V
    *     ImmutableSortedMap#of(Comparable, Object, Comparable, Object, Comparable, Object,
    *     Comparable, Object, Comparable, Object)}.</b>
    */
+  @DoNotCall("Pass keys of type Comparable")
   @Deprecated
   public static <K, V> ImmutableSortedMap<K, V> of(
       K k1, V v1, K k2, V v2, K k3, V v3, K k4, V v4, K k5, V v5) {
     throw new UnsupportedOperationException();
   }
 
+  /**
+   * Not supported. <b>You are attempting to create a map that may contain non-{@code Comparable}
+   * keys.</b> Proper calls will resolve to the version in {@code ImmutableSortedMap}, not this
+   * dummy version.
+   *
+   * @throws UnsupportedOperationException always
+   * @deprecated <b>Pass keys of type {@code Comparable} to use {@link
+   *     ImmutableSortedMap#of(Comparable, Object, Comparable, Object, Comparable, Object,
+   *     Comparable, Object, Comparable, Object)}.</b>
+   */
+  @DoNotCall("Pass keys of type Comparable")
+  @Deprecated
+  public static <K, V> ImmutableSortedMap<K, V> of(
+      K k1, V v1, K k2, V v2, K k3, V v3, K k4, V v4, K k5, V v5, K k6, V v6) {
+    throw new UnsupportedOperationException();
+  }
+
+  /**
+   * Not supported. <b>You are attempting to create a map that may contain non-{@code Comparable}
+   * keys.</b> Proper calls will resolve to the version in {@code ImmutableSortedMap}, not this
+   * dummy version.
+   *
+   * @throws UnsupportedOperationException always
+   * @deprecated <b>Pass keys of type {@code Comparable} to use {@link
+   *     ImmutableSortedMap#of(Comparable, Object, Comparable, Object, Comparable, Object,
+   *     Comparable, Object, Comparable, Object)}.</b>
+   */
+  @DoNotCall("Pass keys of type Comparable")
+  @Deprecated
+  public static <K, V> ImmutableSortedMap<K, V> of(
+      K k1, V v1, K k2, V v2, K k3, V v3, K k4, V v4, K k5, V v5, K k6, V v6, K k7, V v7) {
+    throw new UnsupportedOperationException();
+  }
+
+  /**
+   * Not supported. <b>You are attempting to create a map that may contain non-{@code Comparable}
+   * keys.</b> Proper calls will resolve to the version in {@code ImmutableSortedMap}, not this
+   * dummy version.
+   *
+   * @throws UnsupportedOperationException always
+   * @deprecated <b>Pass keys of type {@code Comparable} to use {@link
+   *     ImmutableSortedMap#of(Comparable, Object, Comparable, Object, Comparable, Object,
+   *     Comparable, Object, Comparable, Object)}.</b>
+   */
+  @DoNotCall("Pass keys of type Comparable")
+  @Deprecated
+  public static <K, V> ImmutableSortedMap<K, V> of(
+      K k1,
+      V v1,
+      K k2,
+      V v2,
+      K k3,
+      V v3,
+      K k4,
+      V v4,
+      K k5,
+      V v5,
+      K k6,
+      V v6,
+      K k7,
+      V v7,
+      K k8,
+      V v8) {
+    throw new UnsupportedOperationException();
+  }
+
+  /**
+   * Not supported. <b>You are attempting to create a map that may contain non-{@code Comparable}
+   * keys.</b> Proper calls will resolve to the version in {@code ImmutableSortedMap}, not this
+   * dummy version.
+   *
+   * @throws UnsupportedOperationException always
+   * @deprecated <b>Pass keys of type {@code Comparable} to use {@link
+   *     ImmutableSortedMap#of(Comparable, Object, Comparable, Object, Comparable, Object,
+   *     Comparable, Object, Comparable, Object)}.</b>
+   */
+  @DoNotCall("Pass keys of type Comparable")
+  @Deprecated
+  public static <K, V> ImmutableSortedMap<K, V> of(
+      K k1,
+      V v1,
+      K k2,
+      V v2,
+      K k3,
+      V v3,
+      K k4,
+      V v4,
+      K k5,
+      V v5,
+      K k6,
+      V v6,
+      K k7,
+      V v7,
+      K k8,
+      V v8,
+      K k9,
+      V v9) {
+    throw new UnsupportedOperationException();
+  }
+
+  /**
+   * Not supported. <b>You are attempting to create a map that may contain non-{@code Comparable}
+   * keys.</b> Proper calls will resolve to the version in {@code ImmutableSortedMap}, not this
+   * dummy version.
+   *
+   * @throws UnsupportedOperationException always
+   * @deprecated <b>Pass keys of type {@code Comparable} to use {@link
+   *     ImmutableSortedMap#of(Comparable, Object, Comparable, Object, Comparable, Object,
+   *     Comparable, Object, Comparable, Object)}.</b>
+   */
+  @DoNotCall("Pass keys of type Comparable")
+  @Deprecated
+  public static <K, V> ImmutableSortedMap<K, V> of(
+      K k1,
+      V v1,
+      K k2,
+      V v2,
+      K k3,
+      V v3,
+      K k4,
+      V v4,
+      K k5,
+      V v5,
+      K k6,
+      V v6,
+      K k7,
+      V v7,
+      K k8,
+      V v8,
+      K k9,
+      V v9,
+      K k10,
+      V v10) {
+    throw new UnsupportedOperationException();
+  }
+
+  /**
+   * Not supported. Use {@code ImmutableSortedMap.copyOf(ImmutableMap.ofEntries(...))}.
+   *
+   * @deprecated Use {@code ImmutableSortedMap.copyOf(ImmutableMap.ofEntries(...))}.
+   */
+  @DoNotCall("ImmutableSortedMap.ofEntries not currently available; use ImmutableSortedMap.copyOf")
+  @Deprecated
+  public static <K, V> ImmutableSortedMap<K, V> ofEntries(
+      Entry<? extends K, ? extends V>... entries) {
+    throw new UnsupportedOperationException();
+  }
+
   // No copyOf() fauxveride; see ImmutableSortedSetFauxverideShim.
 }
diff --git a/guava/src/com/google/common/collect/ImmutableSortedMultiset.java b/guava/src/com/google/common/collect/ImmutableSortedMultiset.java
index ceb663b8e14c..0638df04e09d 100644
--- a/guava/src/com/google/common/collect/ImmutableSortedMultiset.java
+++ b/guava/src/com/google/common/collect/ImmutableSortedMultiset.java
@@ -31,6 +31,8 @@
 import java.util.function.Function;
 import java.util.function.ToIntFunction;
 import java.util.stream.Collector;
+import javax.annotation.CheckForNull;
+import org.checkerframework.checker.nullness.qual.Nullable;
 
 /**
  * A {@link SortedMultiset} whose contents will never change, with many other important properties
@@ -43,12 +45,13 @@
  * collection will not correctly obey its specification.
  *
  * <p>See the Guava User Guide article on <a href=
- * "https://github.com/google/guava/wiki/ImmutableCollectionsExplained"> immutable collections</a>.
+ * "https://github.com/google/guava/wiki/ImmutableCollectionsExplained">immutable collections</a>.
  *
  * @author Louis Wasserman
  * @since 12.0
  */
 @GwtIncompatible // hasn't been tested yet
+@ElementTypesAreNonnullByDefault
 public abstract class ImmutableSortedMultiset<E> extends ImmutableSortedMultisetFauxverideShim<E>
     implements SortedMultiset<E> {
   // TODO(lowasser): GWT compatibility
@@ -78,10 +81,11 @@ public abstract class ImmutableSortedMultiset<E> extends ImmutableSortedMultiset
    *
    * @since 22.0
    */
-  public static <T, E> Collector<T, ?, ImmutableSortedMultiset<E>> toImmutableSortedMultiset(
-      Comparator<? super E> comparator,
-      Function<? super T, ? extends E> elementFunction,
-      ToIntFunction<? super T> countFunction) {
+  public static <T extends @Nullable Object, E>
+      Collector<T, ?, ImmutableSortedMultiset<E>> toImmutableSortedMultiset(
+          Comparator<? super E> comparator,
+          Function<? super T, ? extends E> elementFunction,
+          ToIntFunction<? super T> countFunction) {
     checkNotNull(comparator);
     checkNotNull(elementFunction);
     checkNotNull(countFunction);
@@ -96,7 +100,11 @@ public abstract class ImmutableSortedMultiset<E> extends ImmutableSortedMultiset
         (Multiset<E> multiset) -> copyOfSortedEntries(comparator, multiset.entrySet()));
   }
 
-  /** Returns the empty immutable sorted multiset. */
+  /**
+   * Returns the empty immutable sorted multiset.
+   *
+   * <p><b>Performance note:</b> the instance returned is a singleton.
+   */
   @SuppressWarnings("unchecked")
   public static <E> ImmutableSortedMultiset<E> of() {
     return (ImmutableSortedMultiset) RegularImmutableSortedMultiset.NATURAL_EMPTY_MULTISET;
@@ -116,7 +124,6 @@ public static <E extends Comparable<? super E>> ImmutableSortedMultiset<E> of(E
    *
    * @throws NullPointerException if any element is null
    */
-  @SuppressWarnings("unchecked")
   public static <E extends Comparable<? super E>> ImmutableSortedMultiset<E> of(E e1, E e2) {
     return copyOf(Ordering.natural(), Arrays.asList(e1, e2));
   }
@@ -127,7 +134,6 @@ public static <E extends Comparable<? super E>> ImmutableSortedMultiset<E> of(E
    *
    * @throws NullPointerException if any element is null
    */
-  @SuppressWarnings("unchecked")
   public static <E extends Comparable<? super E>> ImmutableSortedMultiset<E> of(E e1, E e2, E e3) {
     return copyOf(Ordering.natural(), Arrays.asList(e1, e2, e3));
   }
@@ -138,7 +144,6 @@ public static <E extends Comparable<? super E>> ImmutableSortedMultiset<E> of(E
    *
    * @throws NullPointerException if any element is null
    */
-  @SuppressWarnings("unchecked")
   public static <E extends Comparable<? super E>> ImmutableSortedMultiset<E> of(
       E e1, E e2, E e3, E e4) {
     return copyOf(Ordering.natural(), Arrays.asList(e1, e2, e3, e4));
@@ -150,7 +155,6 @@ public static <E extends Comparable<? super E>> ImmutableSortedMultiset<E> of(
    *
    * @throws NullPointerException if any element is null
    */
-  @SuppressWarnings("unchecked")
   public static <E extends Comparable<? super E>> ImmutableSortedMultiset<E> of(
       E e1, E e2, E e3, E e4, E e5) {
     return copyOf(Ordering.natural(), Arrays.asList(e1, e2, e3, e4, e5));
@@ -162,7 +166,6 @@ public static <E extends Comparable<? super E>> ImmutableSortedMultiset<E> of(
    *
    * @throws NullPointerException if any element is null
    */
-  @SuppressWarnings("unchecked")
   public static <E extends Comparable<? super E>> ImmutableSortedMultiset<E> of(
       E e1, E e2, E e3, E e4, E e5, E e6, E... remaining) {
     int size = remaining.length + 6;
@@ -328,7 +331,7 @@ public final Comparator<? super E> comparator() {
   @Override
   public abstract ImmutableSortedSet<E> elementSet();
 
-  @LazyInit transient ImmutableSortedMultiset<E> descendingMultiset;
+  @LazyInit @CheckForNull transient ImmutableSortedMultiset<E> descendingMultiset;
 
   @Override
   public ImmutableSortedMultiset<E> descendingMultiset() {
@@ -354,6 +357,7 @@ public ImmutableSortedMultiset<E> descendingMultiset() {
   @Deprecated
   @Override
   @DoNotCall("Always throws UnsupportedOperationException")
+  @CheckForNull
   public final Entry<E> pollFirstEntry() {
     throw new UnsupportedOperationException();
   }
@@ -370,6 +374,7 @@ public final Entry<E> pollFirstEntry() {
   @Deprecated
   @Override
   @DoNotCall("Always throws UnsupportedOperationException")
+  @CheckForNull
   public final Entry<E> pollLastEntry() {
     throw new UnsupportedOperationException();
   }
diff --git a/guava/src/com/google/common/collect/ImmutableSortedMultisetFauxverideShim.java b/guava/src/com/google/common/collect/ImmutableSortedMultisetFauxverideShim.java
index e3f45f751f84..94a2f560da4b 100644
--- a/guava/src/com/google/common/collect/ImmutableSortedMultisetFauxverideShim.java
+++ b/guava/src/com/google/common/collect/ImmutableSortedMultisetFauxverideShim.java
@@ -15,9 +15,11 @@
 package com.google.common.collect;
 
 import com.google.common.annotations.GwtIncompatible;
+import com.google.errorprone.annotations.DoNotCall;
 import java.util.function.Function;
 import java.util.function.ToIntFunction;
 import java.util.stream.Collector;
+import org.checkerframework.checker.nullness.qual.Nullable;
 
 /**
  * "Overrides" the {@link ImmutableMultiset} static methods that lack {@link
@@ -37,6 +39,7 @@
  * @author Louis Wasserman
  */
 @GwtIncompatible
+@ElementTypesAreNonnullByDefault
 abstract class ImmutableSortedMultisetFauxverideShim<E> extends ImmutableMultiset<E> {
   /**
    * Not supported. Use {@link ImmutableSortedMultiset#toImmutableSortedMultiset} instead. This
@@ -47,6 +50,7 @@ abstract class ImmutableSortedMultisetFauxverideShim<E> extends ImmutableMultise
    * @deprecated Use {@link ImmutableSortedMultiset#toImmutableSortedMultiset}.
    * @since 21.0
    */
+  @DoNotCall("Use toImmutableSortedMultiset.")
   @Deprecated
   public static <E> Collector<E, ?, ImmutableMultiset<E>> toImmutableMultiset() {
     throw new UnsupportedOperationException();
@@ -61,9 +65,12 @@ abstract class ImmutableSortedMultisetFauxverideShim<E> extends ImmutableMultise
    * @deprecated Use {@link ImmutableSortedMultiset#toImmutableSortedMultiset}.
    * @since 22.0
    */
+  @DoNotCall("Use toImmutableSortedMultiset.")
   @Deprecated
-  public static <T, E> Collector<T, ?, ImmutableMultiset<E>> toImmutableMultiset(
-      Function<? super T, ? extends E> elementFunction, ToIntFunction<? super T> countFunction) {
+  public static <T extends @Nullable Object, E>
+      Collector<T, ?, ImmutableMultiset<E>> toImmutableMultiset(
+          Function<? super T, ? extends E> elementFunction,
+          ToIntFunction<? super T> countFunction) {
     throw new UnsupportedOperationException();
   }
 
@@ -75,6 +82,7 @@ abstract class ImmutableSortedMultisetFauxverideShim<E> extends ImmutableMultise
    * @throws UnsupportedOperationException always
    * @deprecated Use {@link ImmutableSortedMultiset#naturalOrder}, which offers better type-safety.
    */
+  @DoNotCall("Use naturalOrder.")
   @Deprecated
   public static <E> ImmutableSortedMultiset.Builder<E> builder() {
     throw new UnsupportedOperationException();
@@ -89,6 +97,7 @@ public static <E> ImmutableSortedMultiset.Builder<E> builder() {
    * @deprecated <b>Pass a parameter of type {@code Comparable} to use {@link
    *     ImmutableSortedMultiset#of(Comparable)}.</b>
    */
+  @DoNotCall("Elements must be Comparable. (Or, pass a Comparator to orderedBy or copyOf.)")
   @Deprecated
   public static <E> ImmutableSortedMultiset<E> of(E element) {
     throw new UnsupportedOperationException();
@@ -103,6 +112,7 @@ public static <E> ImmutableSortedMultiset<E> of(E element) {
    * @deprecated <b>Pass the parameters of type {@code Comparable} to use {@link
    *     ImmutableSortedMultiset#of(Comparable, Comparable)}.</b>
    */
+  @DoNotCall("Elements must be Comparable. (Or, pass a Comparator to orderedBy or copyOf.)")
   @Deprecated
   public static <E> ImmutableSortedMultiset<E> of(E e1, E e2) {
     throw new UnsupportedOperationException();
@@ -117,6 +127,7 @@ public static <E> ImmutableSortedMultiset<E> of(E e1, E e2) {
    * @deprecated <b>Pass the parameters of type {@code Comparable} to use {@link
    *     ImmutableSortedMultiset#of(Comparable, Comparable, Comparable)}.</b>
    */
+  @DoNotCall("Elements must be Comparable. (Or, pass a Comparator to orderedBy or copyOf.)")
   @Deprecated
   public static <E> ImmutableSortedMultiset<E> of(E e1, E e2, E e3) {
     throw new UnsupportedOperationException();
@@ -131,6 +142,7 @@ public static <E> ImmutableSortedMultiset<E> of(E e1, E e2, E e3) {
    * @deprecated <b>Pass the parameters of type {@code Comparable} to use {@link
    *     ImmutableSortedMultiset#of(Comparable, Comparable, Comparable, Comparable)}. </b>
    */
+  @DoNotCall("Elements must be Comparable. (Or, pass a Comparator to orderedBy or copyOf.)")
   @Deprecated
   public static <E> ImmutableSortedMultiset<E> of(E e1, E e2, E e3, E e4) {
     throw new UnsupportedOperationException();
@@ -146,6 +158,7 @@ public static <E> ImmutableSortedMultiset<E> of(E e1, E e2, E e3, E e4) {
    *     ImmutableSortedMultiset#of(Comparable, Comparable, Comparable, Comparable, Comparable)} .
    *     </b>
    */
+  @DoNotCall("Elements must be Comparable. (Or, pass a Comparator to orderedBy or copyOf.)")
   @Deprecated
   public static <E> ImmutableSortedMultiset<E> of(E e1, E e2, E e3, E e4, E e5) {
     throw new UnsupportedOperationException();
@@ -161,6 +174,7 @@ public static <E> ImmutableSortedMultiset<E> of(E e1, E e2, E e3, E e4, E e5) {
    *     ImmutableSortedMultiset#of(Comparable, Comparable, Comparable, Comparable, Comparable,
    *     Comparable, Comparable...)} . </b>
    */
+  @DoNotCall("Elements must be Comparable. (Or, pass a Comparator to orderedBy or copyOf.)")
   @Deprecated
   public static <E> ImmutableSortedMultiset<E> of(
       E e1, E e2, E e3, E e4, E e5, E e6, E... remaining) {
@@ -176,6 +190,7 @@ public static <E> ImmutableSortedMultiset<E> of(
    * @deprecated <b>Pass parameters of type {@code Comparable} to use {@link
    *     ImmutableSortedMultiset#copyOf(Comparable[])}.</b>
    */
+  @DoNotCall("Elements must be Comparable. (Or, pass a Comparator to orderedBy or copyOf.)")
   @Deprecated
   public static <E> ImmutableSortedMultiset<E> copyOf(E[] elements) {
     throw new UnsupportedOperationException();
diff --git a/guava/src/com/google/common/collect/ImmutableSortedSet.java b/guava/src/com/google/common/collect/ImmutableSortedSet.java
index f8160dde3903..844c729400e9 100644
--- a/guava/src/com/google/common/collect/ImmutableSortedSet.java
+++ b/guava/src/com/google/common/collect/ImmutableSortedSet.java
@@ -39,6 +39,7 @@
 import java.util.Spliterators;
 import java.util.function.Consumer;
 import java.util.stream.Collector;
+import javax.annotation.CheckForNull;
 import org.checkerframework.checker.nullness.qual.Nullable;
 import org.checkerframework.dataflow.qual.SideEffectFree;
 import org.checkerframework.framework.qual.AnnotatedFor;
@@ -54,7 +55,7 @@
  * collection will not correctly obey its specification.
  *
  * <p>See the Guava User Guide article on <a href=
- * "https://github.com/google/guava/wiki/ImmutableCollectionsExplained"> immutable collections</a>.
+ * "https://github.com/google/guava/wiki/ImmutableCollectionsExplained">immutable collections</a>.
  *
  * @author Jared Levy
  * @author Louis Wasserman
@@ -64,6 +65,7 @@
 @AnnotatedFor({"nullness"})
 @GwtCompatible(serializable = true, emulated = true)
 @SuppressWarnings("serial") // we're overriding default serialization
+@ElementTypesAreNonnullByDefault
 public abstract class ImmutableSortedSet<E> extends ImmutableSortedSetFauxverideShim<E>
     implements NavigableSet<E>, SortedIterable<E> {
   static final int SPLITERATOR_CHARACTERISTICS =
@@ -91,7 +93,11 @@ static <E> RegularImmutableSortedSet<E> emptySet(Comparator<? super E> comparato
     }
   }
 
-  /** Returns the empty immutable sorted set. */
+  /**
+   * Returns the empty immutable sorted set.
+   *
+   * <p><b>Performance note:</b> the instance returned is a singleton.
+   */
   public static <E> ImmutableSortedSet<E> of() {
     return (ImmutableSortedSet<E>) RegularImmutableSortedSet.NATURAL_EMPTY_SET;
   }
@@ -574,16 +580,16 @@ public ImmutableSortedSet<E> build() {
     }
   }
 
-  int unsafeCompare(Object a, Object b) {
+  int unsafeCompare(Object a, @CheckForNull Object b) {
     return unsafeCompare(comparator, a, b);
   }
 
-  static int unsafeCompare(Comparator<?> comparator, Object a, Object b) {
+  static int unsafeCompare(Comparator<?> comparator, Object a, @CheckForNull Object b) {
     // Pretend the comparator can compare anything. If it turns out it can't
-    // compare a and b, we should get a CCE on the subsequent line. Only methods
-    // that are spec'd to throw CCE should call this.
-    @SuppressWarnings("unchecked")
-    Comparator<Object> unsafeComparator = (Comparator<Object>) comparator;
+    // compare a and b, we should get a CCE or NPE on the subsequent line. Only methods
+    // that are spec'd to throw CCE and NPE should call this.
+    @SuppressWarnings({"unchecked", "nullness"})
+    Comparator<@Nullable Object> unsafeComparator = (Comparator<@Nullable Object>) comparator;
     return unsafeComparator.compare(a, b);
   }
 
@@ -694,18 +700,21 @@ abstract ImmutableSortedSet<E> subSetImpl(
   /** @since 12.0 */
   @GwtIncompatible // NavigableSet
   @Override
+  @CheckForNull
   public E lower(E e) {
     return Iterators.getNext(headSet(e, false).descendingIterator(), null);
   }
 
   /** @since 12.0 */
   @Override
+  @CheckForNull
   public E floor(E e) {
     return Iterators.getNext(headSet(e, true).descendingIterator(), null);
   }
 
   /** @since 12.0 */
   @Override
+  @CheckForNull
   public E ceiling(E e) {
     return Iterables.getFirst(tailSet(e, true), null);
   }
@@ -713,6 +722,7 @@ public E ceiling(E e) {
   /** @since 12.0 */
   @GwtIncompatible // NavigableSet
   @Override
+  @CheckForNull
   public E higher(E e) {
     return Iterables.getFirst(tailSet(e, false), null);
   }
@@ -739,6 +749,7 @@ public E last() {
   @GwtIncompatible // NavigableSet
   @Override
   @DoNotCall("Always throws UnsupportedOperationException")
+  @CheckForNull
   public final E pollFirst() {
     throw new UnsupportedOperationException();
   }
@@ -755,12 +766,14 @@ public final E pollFirst() {
   @GwtIncompatible // NavigableSet
   @Override
   @DoNotCall("Always throws UnsupportedOperationException")
+  @CheckForNull
   public final E pollLast() {
     throw new UnsupportedOperationException();
   }
 
   @GwtIncompatible // NavigableSet
   @LazyInit
+  @CheckForNull
   transient ImmutableSortedSet<E> descendingSet;
 
   /** @since 12.0 */
@@ -811,7 +824,7 @@ public Comparator<? super E> getComparator() {
   public abstract UnmodifiableIterator<E> descendingIterator();
 
   /** Returns the position of an element within the set, or -1 if not present. */
-  abstract int indexOf(@Nullable Object target);
+  abstract int indexOf(@CheckForNull Object target);
 
   /*
    * This class is used to serialize all ImmutableSortedSet instances,
diff --git a/guava/src/com/google/common/collect/ImmutableSortedSetFauxverideShim.java b/guava/src/com/google/common/collect/ImmutableSortedSetFauxverideShim.java
index 89db23d9b428..a5170e5bfd17 100644
--- a/guava/src/com/google/common/collect/ImmutableSortedSetFauxverideShim.java
+++ b/guava/src/com/google/common/collect/ImmutableSortedSetFauxverideShim.java
@@ -17,6 +17,7 @@
 package com.google.common.collect;
 
 import com.google.common.annotations.GwtIncompatible;
+import com.google.errorprone.annotations.DoNotCall;
 import java.util.stream.Collector;
 import org.checkerframework.framework.qual.AnnotatedFor;
 
@@ -39,7 +40,8 @@
  */
 @AnnotatedFor({"nullness"})
 @GwtIncompatible
-abstract class ImmutableSortedSetFauxverideShim<E> extends ImmutableSet<E> {
+@ElementTypesAreNonnullByDefault
+abstract class ImmutableSortedSetFauxverideShim<E> extends ImmutableSet.CachingAsList<E> {
   /**
    * Not supported. Use {@link ImmutableSortedSet#toImmutableSortedSet} instead. This method exists
    * only to hide {@link ImmutableSet#toImmutableSet} from consumers of {@code ImmutableSortedSet}.
@@ -48,6 +50,7 @@ abstract class ImmutableSortedSetFauxverideShim<E> extends ImmutableSet<E> {
    * @deprecated Use {@link ImmutableSortedSet#toImmutableSortedSet}.
    * @since 21.0
    */
+  @DoNotCall("Use toImmutableSortedSet")
   @Deprecated
   public static <E> Collector<E, ?, ImmutableSet<E>> toImmutableSet() {
     throw new UnsupportedOperationException();
@@ -61,6 +64,7 @@ abstract class ImmutableSortedSetFauxverideShim<E> extends ImmutableSet<E> {
    * @throws UnsupportedOperationException always
    * @deprecated Use {@link ImmutableSortedSet#naturalOrder}, which offers better type-safety.
    */
+  @DoNotCall("Use naturalOrder")
   @Deprecated
   public static <E> ImmutableSortedSet.Builder<E> builder() {
     throw new UnsupportedOperationException();
@@ -73,6 +77,7 @@ public static <E> ImmutableSortedSet.Builder<E> builder() {
    * @throws UnsupportedOperationException always
    * @deprecated Not supported by ImmutableSortedSet.
    */
+  @DoNotCall("Use naturalOrder (which does not accept an expected size)")
   @Deprecated
   public static <E> ImmutableSortedSet.Builder<E> builderWithExpectedSize(int expectedSize) {
     throw new UnsupportedOperationException();
@@ -87,6 +92,7 @@ public static <E> ImmutableSortedSet.Builder<E> builderWithExpectedSize(int expe
    * @deprecated <b>Pass a parameter of type {@code Comparable} to use {@link
    *     ImmutableSortedSet#of(Comparable)}.</b>
    */
+  @DoNotCall("Pass a parameter of type Comparable")
   @Deprecated
   public static <E> ImmutableSortedSet<E> of(E element) {
     throw new UnsupportedOperationException();
@@ -101,6 +107,7 @@ public static <E> ImmutableSortedSet<E> of(E element) {
    * @deprecated <b>Pass the parameters of type {@code Comparable} to use {@link
    *     ImmutableSortedSet#of(Comparable, Comparable)}.</b>
    */
+  @DoNotCall("Pass parameters of type Comparable")
   @Deprecated
   public static <E> ImmutableSortedSet<E> of(E e1, E e2) {
     throw new UnsupportedOperationException();
@@ -115,6 +122,7 @@ public static <E> ImmutableSortedSet<E> of(E e1, E e2) {
    * @deprecated <b>Pass the parameters of type {@code Comparable} to use {@link
    *     ImmutableSortedSet#of(Comparable, Comparable, Comparable)}.</b>
    */
+  @DoNotCall("Pass parameters of type Comparable")
   @Deprecated
   public static <E> ImmutableSortedSet<E> of(E e1, E e2, E e3) {
     throw new UnsupportedOperationException();
@@ -129,6 +137,7 @@ public static <E> ImmutableSortedSet<E> of(E e1, E e2, E e3) {
    * @deprecated <b>Pass the parameters of type {@code Comparable} to use {@link
    *     ImmutableSortedSet#of(Comparable, Comparable, Comparable, Comparable)}. </b>
    */
+  @DoNotCall("Pass parameters of type Comparable")
   @Deprecated
   public static <E> ImmutableSortedSet<E> of(E e1, E e2, E e3, E e4) {
     throw new UnsupportedOperationException();
@@ -143,6 +152,7 @@ public static <E> ImmutableSortedSet<E> of(E e1, E e2, E e3, E e4) {
    * @deprecated <b>Pass the parameters of type {@code Comparable} to use {@link
    *     ImmutableSortedSet#of( Comparable, Comparable, Comparable, Comparable, Comparable)}. </b>
    */
+  @DoNotCall("Pass parameters of type Comparable")
   @Deprecated
   public static <E> ImmutableSortedSet<E> of(E e1, E e2, E e3, E e4, E e5) {
     throw new UnsupportedOperationException();
@@ -158,6 +168,7 @@ public static <E> ImmutableSortedSet<E> of(E e1, E e2, E e3, E e4, E e5) {
    *     ImmutableSortedSet#of(Comparable, Comparable, Comparable, Comparable, Comparable,
    *     Comparable, Comparable...)}. </b>
    */
+  @DoNotCall("Pass parameters of type Comparable")
   @Deprecated
   public static <E> ImmutableSortedSet<E> of(E e1, E e2, E e3, E e4, E e5, E e6, E... remaining) {
     throw new UnsupportedOperationException();
@@ -172,6 +183,7 @@ public static <E> ImmutableSortedSet<E> of(E e1, E e2, E e3, E e4, E e5, E e6, E
    * @deprecated <b>Pass parameters of type {@code Comparable} to use {@link
    *     ImmutableSortedSet#copyOf(Comparable[])}.</b>
    */
+  @DoNotCall("Pass parameters of type Comparable")
   @Deprecated
   public static <E> ImmutableSortedSet<E> copyOf(E[] elements) {
     throw new UnsupportedOperationException();
diff --git a/guava/src/com/google/common/collect/ImmutableTable.java b/guava/src/com/google/common/collect/ImmutableTable.java
index 62a2d2d20db6..033c271e6f69 100644
--- a/guava/src/com/google/common/collect/ImmutableTable.java
+++ b/guava/src/com/google/common/collect/ImmutableTable.java
@@ -32,6 +32,7 @@
 import java.util.function.BinaryOperator;
 import java.util.function.Function;
 import java.util.stream.Collector;
+import javax.annotation.CheckForNull;
 import org.checkerframework.checker.nullness.qual.Nullable;
 
 /**
@@ -39,12 +40,13 @@
  * at {@link ImmutableCollection}.
  *
  * <p>See the Guava User Guide article on <a href=
- * "https://github.com/google/guava/wiki/ImmutableCollectionsExplained"> immutable collections</a>.
+ * "https://github.com/google/guava/wiki/ImmutableCollectionsExplained">immutable collections</a>.
  *
  * @author Gregory Kick
  * @since 11.0
  */
 @GwtCompatible
+@ElementTypesAreNonnullByDefault
 public abstract class ImmutableTable<R, C, V> extends AbstractTable<R, C, V>
     implements Serializable {
 
@@ -58,10 +60,11 @@ public abstract class ImmutableTable<R, C, V> extends AbstractTable<R, C, V>
    *
    * @since 21.0
    */
-  public static <T, R, C, V> Collector<T, ?, ImmutableTable<R, C, V>> toImmutableTable(
-      Function<? super T, ? extends R> rowFunction,
-      Function<? super T, ? extends C> columnFunction,
-      Function<? super T, ? extends V> valueFunction) {
+  public static <T extends @Nullable Object, R, C, V>
+      Collector<T, ?, ImmutableTable<R, C, V>> toImmutableTable(
+          Function<? super T, ? extends R> rowFunction,
+          Function<? super T, ? extends C> columnFunction,
+          Function<? super T, ? extends V> valueFunction) {
     return TableCollectors.toImmutableTable(rowFunction, columnFunction, valueFunction);
   }
 
@@ -76,16 +79,21 @@ public abstract class ImmutableTable<R, C, V> extends AbstractTable<R, C, V>
    *
    * @since 21.0
    */
-  public static <T, R, C, V> Collector<T, ?, ImmutableTable<R, C, V>> toImmutableTable(
-      Function<? super T, ? extends R> rowFunction,
-      Function<? super T, ? extends C> columnFunction,
-      Function<? super T, ? extends V> valueFunction,
-      BinaryOperator<V> mergeFunction) {
+  public static <T extends @Nullable Object, R, C, V>
+      Collector<T, ?, ImmutableTable<R, C, V>> toImmutableTable(
+          Function<? super T, ? extends R> rowFunction,
+          Function<? super T, ? extends C> columnFunction,
+          Function<? super T, ? extends V> valueFunction,
+          BinaryOperator<V> mergeFunction) {
     return TableCollectors.toImmutableTable(
         rowFunction, columnFunction, valueFunction, mergeFunction);
   }
 
-  /** Returns an empty immutable table. */
+  /**
+   * Returns an empty immutable table.
+   *
+   * <p><b>Performance note:</b> the instance returned is a singleton.
+   */
   @SuppressWarnings("unchecked")
   public static <R, C, V> ImmutableTable<R, C, V> of() {
     return (ImmutableTable<R, C, V>) SparseImmutableTable.EMPTY;
@@ -158,7 +166,7 @@ static <R, C, V> Cell<R, C, V> cellOf(R rowKey, C columnKey, V value) {
    *         .put(1, 'A', "foo")
    *         .put(1, 'B', "bar")
    *         .put(2, 'A', "baz")
-   *         .build();
+   *         .buildOrThrow();
    * }</pre>
    *
    * <p>By default, the order in which cells are added to the builder determines the iteration
@@ -169,16 +177,16 @@ static <R, C, V> Cell<R, C, V> cellOf(R rowKey, C columnKey, V value) {
    * <p>For empty or single-cell immutable tables, {@link #of()} and {@link #of(Object, Object,
    * Object)} are even more convenient.
    *
-   * <p>Builder instances can be reused - it is safe to call {@link #build} multiple times to build
-   * multiple tables in series. Each table is a superset of the tables created before it.
+   * <p>Builder instances can be reused - it is safe to call {@link #buildOrThrow} multiple times to
+   * build multiple tables in series. Each table is a superset of the tables created before it.
    *
    * @since 11.0
    */
   @DoNotMock
   public static final class Builder<R, C, V> {
     private final List<Cell<R, C, V>> cells = Lists.newArrayList();
-    private @Nullable Comparator<? super R> rowComparator;
-    private @Nullable Comparator<? super C> columnComparator;
+    @CheckForNull private Comparator<? super R> rowComparator;
+    @CheckForNull private Comparator<? super C> columnComparator;
 
     /**
      * Creates a new builder. The returned builder is equivalent to the builder generated by {@link
@@ -252,9 +260,24 @@ Builder<R, C, V> combine(Builder<R, C, V> other) {
     /**
      * Returns a newly-created immutable table.
      *
+     * <p>Prefer the equivalent method {@link #buildOrThrow()} to make it explicit that the method
+     * will throw an exception if there are duplicate key pairs. The {@code build()} method will
+     * soon be deprecated.
+     *
      * @throws IllegalArgumentException if duplicate key pairs were added
      */
     public ImmutableTable<R, C, V> build() {
+      return buildOrThrow();
+    }
+
+    /**
+     * Returns a newly-created immutable table, or throws an exception if duplicate key pairs were
+     * added.
+     *
+     * @throws IllegalArgumentException if duplicate key pairs were added
+     * @since 31.0
+     */
+    public ImmutableTable<R, C, V> buildOrThrow() {
       int size = cells.size();
       switch (size) {
         case 0:
@@ -353,12 +376,12 @@ public ImmutableSet<R> rowKeySet() {
   public abstract ImmutableMap<R, Map<C, V>> rowMap();
 
   @Override
-  public boolean contains(@Nullable Object rowKey, @Nullable Object columnKey) {
+  public boolean contains(@CheckForNull Object rowKey, @CheckForNull Object columnKey) {
     return get(rowKey, columnKey) != null;
   }
 
   @Override
-  public boolean containsValue(@Nullable Object value) {
+  public boolean containsValue(@CheckForNull Object value) {
     return values().contains(value);
   }
 
@@ -385,6 +408,7 @@ public final void clear() {
   @Deprecated
   @Override
   @DoNotCall("Always throws UnsupportedOperationException")
+  @CheckForNull
   public final V put(R rowKey, C columnKey, V value) {
     throw new UnsupportedOperationException();
   }
@@ -412,7 +436,8 @@ public final void putAll(Table<? extends R, ? extends C, ? extends V> table) {
   @Deprecated
   @Override
   @DoNotCall("Always throws UnsupportedOperationException")
-  public final V remove(Object rowKey, Object columnKey) {
+  @CheckForNull
+  public final V remove(@CheckForNull Object rowKey, @CheckForNull Object columnKey) {
     throw new UnsupportedOperationException();
   }
 
diff --git a/guava/src/com/google/common/collect/IndexedImmutableSet.java b/guava/src/com/google/common/collect/IndexedImmutableSet.java
index 0168913893b0..20dfacbab86a 100644
--- a/guava/src/com/google/common/collect/IndexedImmutableSet.java
+++ b/guava/src/com/google/common/collect/IndexedImmutableSet.java
@@ -22,9 +22,11 @@
 import com.google.common.annotations.GwtIncompatible;
 import java.util.Spliterator;
 import java.util.function.Consumer;
+import org.checkerframework.checker.nullness.qual.Nullable;
 
 @GwtCompatible(emulated = true)
-abstract class IndexedImmutableSet<E> extends ImmutableSet<E> {
+@ElementTypesAreNonnullByDefault
+abstract class IndexedImmutableSet<E> extends ImmutableSet.CachingAsList<E> {
   abstract E get(int index);
 
   @Override
@@ -48,7 +50,7 @@ public void forEach(Consumer<? super E> consumer) {
 
   @Override
   @GwtIncompatible
-  int copyIntoArray(Object[] dst, int offset) {
+  int copyIntoArray(@Nullable Object[] dst, int offset) {
     return asList().copyIntoArray(dst, offset);
   }
 
diff --git a/guava/src/com/google/common/collect/Interner.java b/guava/src/com/google/common/collect/Interner.java
index 310bfca6f0b3..bfc2035f101b 100644
--- a/guava/src/com/google/common/collect/Interner.java
+++ b/guava/src/com/google/common/collect/Interner.java
@@ -16,7 +16,6 @@
 
 package com.google.common.collect;
 
-import com.google.common.annotations.Beta;
 import com.google.common.annotations.GwtIncompatible;
 import com.google.errorprone.annotations.CanIgnoreReturnValue;
 import com.google.errorprone.annotations.DoNotMock;
@@ -32,9 +31,9 @@
  * @author Kevin Bourrillion
  * @since 3.0
  */
-@Beta
 @DoNotMock("Use Interners.new*Interner")
 @GwtIncompatible
+@ElementTypesAreNonnullByDefault
 public interface Interner<E> {
   /**
    * Chooses and returns the representative instance for any of a collection of instances that are
diff --git a/guava/src/com/google/common/collect/Interners.java b/guava/src/com/google/common/collect/Interners.java
index 061a1cfc7c73..10ae2746332b 100644
--- a/guava/src/com/google/common/collect/Interners.java
+++ b/guava/src/com/google/common/collect/Interners.java
@@ -16,13 +16,13 @@
 
 import static com.google.common.base.Preconditions.checkNotNull;
 
-import com.google.common.annotations.Beta;
 import com.google.common.annotations.GwtIncompatible;
 import com.google.common.annotations.VisibleForTesting;
 import com.google.common.base.Equivalence;
 import com.google.common.base.Function;
 import com.google.common.collect.MapMaker.Dummy;
 import com.google.common.collect.MapMakerInternalMap.InternalEntry;
+import javax.annotation.CheckForNull;
 
 /**
  * Contains static methods pertaining to instances of {@link Interner}.
@@ -30,8 +30,8 @@
  * @author Kevin Bourrillion
  * @since 3.0
  */
-@Beta
 @GwtIncompatible
+@ElementTypesAreNonnullByDefault
 public final class Interners {
   private Interners() {}
 
@@ -81,7 +81,7 @@ public <E> Interner<E> build() {
       if (!strong) {
         mapMaker.weakKeys();
       }
-      return new InternerImpl<E>(mapMaker);
+      return new InternerImpl<>(mapMaker);
     }
   }
 
@@ -124,11 +124,15 @@ private InternerImpl(MapMaker mapMaker) {
     public E intern(E sample) {
       while (true) {
         // trying to read the canonical...
-        InternalEntry<E, Dummy, ?> entry = map.getEntry(sample);
+        @SuppressWarnings("rawtypes") // using raw types to avoid a bug in our nullness checker :(
+        InternalEntry entry = map.getEntry(sample);
         if (entry != null) {
-          E canonical = entry.getKey();
+          Object canonical = entry.getKey();
           if (canonical != null) { // only matters if weak/soft keys are used
-            return canonical;
+            // The compiler would know this is safe if not for our use of raw types (see above).
+            @SuppressWarnings("unchecked")
+            E result = (E) canonical;
+            return result;
           }
         }
 
@@ -154,7 +158,7 @@ public E intern(E sample) {
    * @since 8.0
    */
   public static <E> Function<E, E> asFunction(Interner<E> interner) {
-    return new InternerFunction<E>(checkNotNull(interner));
+    return new InternerFunction<>(checkNotNull(interner));
   }
 
   private static class InternerFunction<E> implements Function<E, E> {
@@ -176,7 +180,7 @@ public int hashCode() {
     }
 
     @Override
-    public boolean equals(Object other) {
+    public boolean equals(@CheckForNull Object other) {
       if (other instanceof InternerFunction) {
         InternerFunction<?> that = (InternerFunction<?>) other;
         return interner.equals(that.interner);
diff --git a/guava/src/com/google/common/collect/Iterables.java b/guava/src/com/google/common/collect/Iterables.java
index fb25a46dbd20..2ec4c614a5ce 100644
--- a/guava/src/com/google/common/collect/Iterables.java
+++ b/guava/src/com/google/common/collect/Iterables.java
@@ -39,6 +39,7 @@
 import java.util.Spliterator;
 import java.util.function.Consumer;
 import java.util.stream.Stream;
+import javax.annotation.CheckForNull;
 import org.checkerframework.checker.nullness.qual.Nullable;
 import org.checkerframework.checker.nullness.qual.PolyNull;
 import org.checkerframework.dataflow.qual.Pure;
@@ -59,7 +60,7 @@
  * absolutely necessary.
  *
  * <p>See the Guava User Guide article on <a href=
- * "https://github.com/google/guava/wiki/CollectionUtilitiesExplained#iterables"> {@code
+ * "https://github.com/google/guava/wiki/CollectionUtilitiesExplained#iterables">{@code
  * Iterables}</a>.
  *
  * @author Kevin Bourrillion
@@ -68,11 +69,13 @@
  */
 @AnnotatedFor({"nullness"})
 @GwtCompatible(emulated = true)
+@ElementTypesAreNonnullByDefault
 public final class Iterables {
   private Iterables() {}
 
   /** Returns an unmodifiable view of {@code iterable}. */
-  public static <T> Iterable<T> unmodifiableIterable(final Iterable<? extends T> iterable) {
+  public static <T extends @Nullable Object> Iterable<T> unmodifiableIterable(
+      final Iterable<? extends T> iterable) {
     checkNotNull(iterable);
     if (iterable instanceof UnmodifiableIterable || iterable instanceof ImmutableCollection) {
       @SuppressWarnings("unchecked") // Since it's unmodifiable, the covariant cast is safe
@@ -93,7 +96,8 @@ public static <E> Iterable<E> unmodifiableIterable(ImmutableCollection<E> iterab
     return checkNotNull(iterable);
   }
 
-  private static final class UnmodifiableIterable<T> extends FluentIterable<T> {
+  private static final class UnmodifiableIterable<T extends @Nullable Object>
+      extends FluentIterable<T> {
     private final Iterable<? extends T> iterable;
 
     private UnmodifiableIterable(Iterable<? extends T> iterable) {
@@ -106,6 +110,7 @@ public Iterator<T> iterator() {
     }
 
     @Override
+    @SuppressWarnings("value:argument")
     public void forEach(Consumer<? super T> action) {
       iterable.forEach(action);
     }
@@ -137,7 +142,8 @@ public static int size(Iterable<?> iterable) {
    * ClassCastException}.
    */
   @Pure
-  public static boolean contains(Iterable<?> iterable, @Nullable Object element) {
+  public static boolean contains(
+      Iterable<? extends @Nullable Object> iterable, @CheckForNull Object element) {
     if (iterable instanceof Collection) {
       Collection<?> collection = (Collection<?>) iterable;
       return Collections2.safeContains(collection, element);
@@ -196,7 +202,8 @@ public static boolean retainAll(Iterable<?> removeFrom, Collection<?> elementsTo
    * @since 2.0
    */
   @CanIgnoreReturnValue
-  public static <T> boolean removeIf(Iterable<T> removeFrom, Predicate<? super T> predicate) {
+  public static <T extends @Nullable Object> boolean removeIf(
+      Iterable<T> removeFrom, Predicate<? super T> predicate) {
     if (removeFrom instanceof Collection) {
       return ((Collection<T>) removeFrom).removeIf(predicate);
     }
@@ -204,7 +211,8 @@ public static <T> boolean removeIf(Iterable<T> removeFrom, Predicate<? super T>
   }
 
   /** Removes and returns the first matching element, or returns {@code null} if there is none. */
-  static <T> @Nullable T removeFirstMatching(
+  @CheckForNull
+  static <T extends @Nullable Object> T removeFirstMatching(
       Iterable<T> removeFrom, Predicate<? super T> predicate) {
     checkNotNull(predicate);
     Iterator<T> iterator = removeFrom.iterator();
@@ -256,7 +264,8 @@ public static String toString(Iterable<?> iterable) {
    * @throws NoSuchElementException if the iterable is empty
    * @throws IllegalArgumentException if the iterable contains multiple elements
    */
-  public static <T> T getOnlyElement(Iterable<T> iterable) {
+  @ParametricNullness
+  public static <T extends @Nullable Object> T getOnlyElement(Iterable<T> iterable) {
     return Iterators.getOnlyElement(iterable.iterator());
   }
 
@@ -269,8 +278,9 @@ public static <T> T getOnlyElement(Iterable<T> iterable) {
    *
    * @throws IllegalArgumentException if the iterator contains multiple elements
    */
-  public static <T> @Nullable T getOnlyElement(
-      Iterable<? extends T> iterable, @Nullable T defaultValue) {
+  @ParametricNullness
+  public static <T extends @Nullable Object> T getOnlyElement(
+      Iterable<? extends T> iterable, @ParametricNullness T defaultValue) {
     return Iterators.getOnlyElement(iterable.iterator(), defaultValue);
   }
 
@@ -282,11 +292,16 @@ public static <T> T getOnlyElement(Iterable<T> iterable) {
    * @return a newly-allocated array into which all the elements of the iterable have been copied
    */
   @GwtIncompatible // Array.newInstance(Class, int)
-  public static <T> T[] toArray(Iterable<? extends T> iterable, Class<T> type) {
+  /*
+   * If we could express Class<@Nonnull T>, we could generalize the type parameter to <T extends
+   * @Nullable Object>, and then we could accept an Iterable<? extends T> and return a plain T[]
+   * instead of a @Nullable T[].
+   */
+  public static <T> @Nullable T[] toArray(Iterable<? extends @Nullable T> iterable, Class<T> type) {
     return toArray(iterable, ObjectArrays.newArray(type, 0));
   }
 
-  static <T> T[] toArray(Iterable<? extends T> iterable, T[] array) {
+  static <T extends @Nullable Object> T[] toArray(Iterable<? extends T> iterable, T[] array) {
     Collection<? extends T> collection = castOrCopyToCollection(iterable);
     return collection.toArray(array);
   }
@@ -297,7 +312,7 @@ static <T> T[] toArray(Iterable<? extends T> iterable, T[] array) {
    * @param iterable the iterable to copy
    * @return a newly-allocated array into which all the elements of the iterable have been copied
    */
-  static Object[] toArray(Iterable<?> iterable) {
+  static @Nullable Object[] toArray(Iterable<?> iterable) {
     return castOrCopyToCollection(iterable).toArray();
   }
 
@@ -306,7 +321,8 @@ static Object[] toArray(Iterable<?> iterable) {
    * returned. Otherwise, an {@link java.util.ArrayList} is created with the contents of the
    * iterable in the same iteration order.
    */
-  private static <E> Collection<E> castOrCopyToCollection(Iterable<E> iterable) {
+  private static <E extends @Nullable Object> Collection<E> castOrCopyToCollection(
+      Iterable<E> iterable) {
     return (iterable instanceof Collection)
         ? (Collection<E>) iterable
         : Lists.newArrayList(iterable.iterator());
@@ -318,7 +334,8 @@ private static <E> Collection<E> castOrCopyToCollection(Iterable<E> iterable) {
    * @return {@code true} if {@code collection} was modified as a result of this operation.
    */
   @CanIgnoreReturnValue
-  public static <T> boolean addAll(Collection<T> addTo, Iterable<? extends T> elementsToAdd) {
+  public static <T extends @Nullable Object> boolean addAll(
+      Collection<T> addTo, Iterable<? extends T> elementsToAdd) {
     if (elementsToAdd instanceof Collection) {
       Collection<? extends T> c = (Collection<? extends T>) elementsToAdd;
       return addTo.addAll(c);
@@ -337,7 +354,7 @@ public static <T> boolean addAll(Collection<T> addTo, Iterable<? extends T> elem
    * @see java.util.Collections#frequency(Collection, Object) Collections.frequency(Collection,
    *     Object)
    */
-  public static int frequency(Iterable<?> iterable, @Nullable Object element) {
+  public static int frequency(Iterable<?> iterable, @CheckForNull Object element) {
     if ((iterable instanceof Multiset)) {
       return ((Multiset<?>) iterable).count(element);
     } else if ((iterable instanceof Set)) {
@@ -364,7 +381,7 @@ public static int frequency(Iterable<?> iterable, @Nullable Object element) {
    * <p><b>Java 8 users:</b> The {@code Stream} equivalent of this method is {@code
    * Stream.generate(() -> iterable).flatMap(Streams::stream)}.
    */
-  public static <T> Iterable<T> cycle(final Iterable<T> iterable) {
+  public static <T extends @Nullable Object> Iterable<T> cycle(final Iterable<T> iterable) {
     checkNotNull(iterable);
     return new FluentIterable<T>() {
       @Override
@@ -375,7 +392,7 @@ public Iterator<T> iterator() {
       @Pure
       @Override
       public Spliterator<T> spliterator() {
-        return Stream.generate(() -> iterable).flatMap(Streams::stream).spliterator();
+        return Stream.generate(() -> iterable).<T>flatMap(Streams::stream).spliterator();
       }
 
       @Override
@@ -406,7 +423,7 @@ public String toString() {
    * and use {@code Stream.generate(() -> collection).flatMap(Collection::stream)}.
    */
   @SafeVarargs
-  public static <T> Iterable<T> cycle(T... elements) {
+  public static <T extends @Nullable Object> Iterable<T> cycle(T... elements) {
     return cycle(Lists.newArrayList(elements));
   }
 
@@ -421,7 +438,8 @@ public static <T> Iterable<T> cycle(T... elements) {
    * <p><b>Java 8 users:</b> The {@code Stream} equivalent of this method is {@code Stream.concat(a,
    * b)}.
    */
-  public static <T> Iterable<T> concat(Iterable<? extends T> a, Iterable<? extends T> b) {
+  public static <T extends @Nullable Object> Iterable<T> concat(
+      Iterable<? extends T> a, Iterable<? extends T> b) {
     return FluentIterable.concat(a, b);
   }
 
@@ -436,7 +454,7 @@ public static <T> Iterable<T> concat(Iterable<? extends T> a, Iterable<? extends
    * <p><b>Java 8 users:</b> The {@code Stream} equivalent of this method is {@code
    * Streams.concat(a, b, c)}.
    */
-  public static <T> Iterable<T> concat(
+  public static <T extends @Nullable Object> Iterable<T> concat(
       Iterable<? extends T> a, Iterable<? extends T> b, Iterable<? extends T> c) {
     return FluentIterable.concat(a, b, c);
   }
@@ -453,7 +471,7 @@ public static <T> Iterable<T> concat(
    * <p><b>Java 8 users:</b> The {@code Stream} equivalent of this method is {@code
    * Streams.concat(a, b, c, d)}.
    */
-  public static <T> Iterable<T> concat(
+  public static <T extends @Nullable Object> Iterable<T> concat(
       Iterable<? extends T> a,
       Iterable<? extends T> b,
       Iterable<? extends T> c,
@@ -475,7 +493,7 @@ public static <T> Iterable<T> concat(
    * @throws NullPointerException if any of the provided iterables is null
    */
   @SafeVarargs
-  public static <T> Iterable<T> concat(Iterable<? extends T>... inputs) {
+  public static <T extends @Nullable Object> Iterable<T> concat(Iterable<? extends T>... inputs) {
     return FluentIterable.concat(inputs);
   }
 
@@ -491,7 +509,8 @@ public static <T> Iterable<T> concat(Iterable<? extends T>... inputs) {
    * <p><b>Java 8 users:</b> The {@code Stream} equivalent of this method is {@code
    * streamOfStreams.flatMap(s -> s)}.
    */
-  public static <T> Iterable<T> concat(Iterable<? extends Iterable<? extends T>> inputs) {
+  public static <T extends @Nullable Object> Iterable<T> concat(
+      Iterable<? extends Iterable<? extends T>> inputs) {
     return FluentIterable.concat(inputs);
   }
 
@@ -504,6 +523,10 @@ public static <T> Iterable<T> concat(Iterable<? extends Iterable<? extends T>> i
    * <p>Iterators returned by the returned iterable do not support the {@link Iterator#remove()}
    * method. The returned lists implement {@link RandomAccess}, whether or not the input list does.
    *
+   * <p><b>Note:</b> The current implementation eagerly allocates storage for {@code size} elements.
+   * As a consequence, passing values like {@code Integer.MAX_VALUE} can lead to {@link
+   * OutOfMemoryError}.
+   *
    * <p><b>Note:</b> if {@code iterable} is a {@link List}, use {@link Lists#partition(List, int)}
    * instead.
    *
@@ -513,7 +536,8 @@ public static <T> Iterable<T> concat(Iterable<? extends Iterable<? extends T>> i
    *     into partitions
    * @throws IllegalArgumentException if {@code size} is nonpositive
    */
-  public static <T> Iterable<List<T>> partition(final Iterable<T> iterable, final int size) {
+  public static <T extends @Nullable Object> Iterable<List<T>> partition(
+      final Iterable<T> iterable, final int size) {
     checkNotNull(iterable);
     checkArgument(size > 0);
     return new FluentIterable<List<T>>() {
@@ -539,12 +563,13 @@ public Iterator<List<T>> iterator() {
    *     into partitions (the final iterable may have trailing null elements)
    * @throws IllegalArgumentException if {@code size} is nonpositive
    */
-  public static <T> Iterable<List<T>> paddedPartition(final Iterable<T> iterable, final int size) {
+  public static <T extends @Nullable Object> Iterable<List<@Nullable T>> paddedPartition(
+      final Iterable<T> iterable, final int size) {
     checkNotNull(iterable);
     checkArgument(size > 0);
-    return new FluentIterable<List<T>>() {
+    return new FluentIterable<List<@Nullable T>>() {
       @Override
-      public Iterator<List<T>> iterator() {
+      public Iterator<List<@Nullable T>> iterator() {
         return Iterators.paddedPartition(iterable.iterator(), size);
       }
     };
@@ -556,7 +581,7 @@ public Iterator<List<T>> iterator() {
    *
    * <p><b>{@code Stream} equivalent:</b> {@link Stream#filter}.
    */
-  public static <T> Iterable<T> filter(
+  public static <T extends @Nullable Object> Iterable<T> filter(
       final Iterable<T> unfiltered, final Predicate<? super T> retainIfTrue) {
     checkNotNull(unfiltered);
     checkNotNull(retainIfTrue);
@@ -570,7 +595,7 @@ public Iterator<T> iterator() {
       public void forEach(Consumer<? super T> action) {
         checkNotNull(action);
         unfiltered.forEach(
-            (T a) -> {
+            (@ParametricNullness T a) -> {
               if (retainIfTrue.test(a)) {
                 action.accept(a);
               }
@@ -611,7 +636,8 @@ public static <T> Iterable<T> filter(final Iterable<?> unfiltered, final Class<T
    *
    * <p><b>{@code Stream} equivalent:</b> {@link Stream#anyMatch}.
    */
-  public static <T> boolean any(Iterable<T> iterable, Predicate<? super T> predicate) {
+  public static <T extends @Nullable Object> boolean any(
+      Iterable<T> iterable, Predicate<? super T> predicate) {
     return Iterators.any(iterable.iterator(), predicate);
   }
 
@@ -621,7 +647,8 @@ public static <T> boolean any(Iterable<T> iterable, Predicate<? super T> predica
    *
    * <p><b>{@code Stream} equivalent:</b> {@link Stream#allMatch}.
    */
-  public static <T> boolean all(Iterable<T> iterable, Predicate<? super T> predicate) {
+  public static <T extends @Nullable Object> boolean all(
+      Iterable<T> iterable, Predicate<? super T> predicate) {
     return Iterators.all(iterable.iterator(), predicate);
   }
 
@@ -634,7 +661,9 @@ public static <T> boolean all(Iterable<T> iterable, Predicate<? super T> predica
    *
    * @throws NoSuchElementException if no element in {@code iterable} matches the given predicate
    */
-  public static <T> T find(Iterable<T> iterable, Predicate<? super T> predicate) {
+  @ParametricNullness
+  public static <T extends @Nullable Object> T find(
+      Iterable<T> iterable, Predicate<? super T> predicate) {
     return Iterators.find(iterable.iterator(), predicate);
   }
 
@@ -648,8 +677,26 @@ public static <T> T find(Iterable<T> iterable, Predicate<? super T> predicate) {
    *
    * @since 7.0
    */
-  public static <T> @Nullable T find(
-      Iterable<? extends T> iterable, Predicate<? super T> predicate, @Nullable T defaultValue) {
+  // The signature we really want here is...
+  //
+  // <T extends @Nullable Object> @JointlyNullable T find(
+  //     Iterable<? extends T> iterable,
+  //     Predicate<? super T> predicate,
+  //     @JointlyNullable T defaultValue);
+  //
+  // ...where "@JointlyNullable" is similar to @PolyNull but slightly different:
+  //
+  // - @PolyNull means "@Nullable or @Nonnull"
+  //   (That would be unsound for an input Iterable<@Nullable Foo>. So, if we wanted to use
+  //   @PolyNull, we would have to restrict this method to non-null <T>. But it has users who pass
+  //   iterables with null elements.)
+  //
+  // - @JointlyNullable means "@Nullable or no annotation"
+  @CheckForNull
+  public static <T extends @Nullable Object> T find(
+      Iterable<? extends T> iterable,
+      Predicate<? super T> predicate,
+      @CheckForNull T defaultValue) {
     return Iterators.find(iterable.iterator(), predicate, defaultValue);
   }
 
@@ -678,7 +725,8 @@ public static <T> Optional<T> tryFind(Iterable<T> iterable, Predicate<? super T>
    *
    * @since 2.0
    */
-  public static <T> int indexOf(Iterable<T> iterable, Predicate<? super T> predicate) {
+  public static <T extends @Nullable Object> int indexOf(
+      Iterable<T> iterable, Predicate<? super T> predicate) {
     return Iterators.indexOf(iterable.iterator(), predicate);
   }
 
@@ -695,7 +743,7 @@ public static <T> int indexOf(Iterable<T> iterable, Predicate<? super T> predica
    *
    * <p><b>{@code Stream} equivalent:</b> {@link Stream#map}
    */
-  public static <F, T> Iterable<T> transform(
+  public static <F extends @Nullable Object, T extends @Nullable Object> Iterable<T> transform(
       final Iterable<F> fromIterable, final Function<? super F, ? extends T> function) {
     checkNotNull(fromIterable);
     checkNotNull(function);
@@ -729,7 +777,8 @@ public Spliterator<T> spliterator() {
    * @throws IndexOutOfBoundsException if {@code position} is negative or greater than or equal to
    *     the size of {@code iterable}
    */
-  public static <T> T get(Iterable<T> iterable, int position) {
+  @ParametricNullness
+  public static <T extends @Nullable Object> T get(Iterable<T> iterable, int position) {
     checkNotNull(iterable);
     return (iterable instanceof List)
         ? ((List<T>) iterable).get(position)
@@ -751,8 +800,9 @@ public static <T> T get(Iterable<T> iterable, int position) {
    * @throws IndexOutOfBoundsException if {@code position} is negative
    * @since 4.0
    */
-  public static <T> @Nullable T get(
-      Iterable<? extends T> iterable, int position, @Nullable T defaultValue) {
+  @ParametricNullness
+  public static <T extends @Nullable Object> T get(
+      Iterable<? extends T> iterable, int position, @ParametricNullness T defaultValue) {
     checkNotNull(iterable);
     Iterators.checkNonnegative(position);
     if (iterable instanceof List) {
@@ -782,7 +832,9 @@ public static <T> T get(Iterable<T> iterable, int position) {
    * @return the first element of {@code iterable} or the default value
    * @since 7.0
    */
-  public static <T> @PolyNull T getFirst(Iterable<? extends T> iterable, @PolyNull T defaultValue) {
+  @ParametricNullness
+  public static <T extends @Nullable Object> T getFirst(
+      Iterable<? extends T> iterable, @ParametricNullness T defaultValue) {
     return Iterators.getNext(iterable.iterator(), defaultValue);
   }
 
@@ -795,7 +847,8 @@ public static <T> T get(Iterable<T> iterable, int position) {
    * @return the last element of {@code iterable}
    * @throws NoSuchElementException if the iterable is empty
    */
-  public static <T> T getLast(Iterable<T> iterable) {
+  @ParametricNullness
+  public static <T extends @Nullable Object> T getLast(Iterable<T> iterable) {
     // TODO(kevinb): Support a concurrently modified collection?
     if (iterable instanceof List) {
       List<T> list = (List<T>) iterable;
@@ -819,7 +872,9 @@ public static <T> T getLast(Iterable<T> iterable) {
    * @return the last element of {@code iterable} or the default value
    * @since 3.0
    */
-  public static <T> @Nullable T getLast(Iterable<? extends T> iterable, @Nullable T defaultValue) {
+  @ParametricNullness
+  public static <T extends @Nullable Object> T getLast(
+      Iterable<? extends T> iterable, @ParametricNullness T defaultValue) {
     if (iterable instanceof Collection) {
       Collection<? extends T> c = (Collection<? extends T>) iterable;
       if (c.isEmpty()) {
@@ -832,7 +887,8 @@ public static <T> T getLast(Iterable<T> iterable) {
     return Iterators.getLast(iterable.iterator(), defaultValue);
   }
 
-  private static <T> T getLastInNonemptyList(List<T> list) {
+  @ParametricNullness
+  private static <T extends @Nullable Object> T getLastInNonemptyList(List<T> list) {
     return list.get(list.size() - 1);
   }
 
@@ -855,7 +911,8 @@ private static <T> T getLastInNonemptyList(List<T> list) {
    *
    * @since 3.0
    */
-  public static <T> Iterable<T> skip(final Iterable<T> iterable, final int numberToSkip) {
+  public static <T extends @Nullable Object> Iterable<T> skip(
+      final Iterable<T> iterable, final int numberToSkip) {
     checkNotNull(iterable);
     checkArgument(numberToSkip >= 0, "number to skip cannot be negative");
 
@@ -885,6 +942,7 @@ public boolean hasNext() {
           }
 
           @Override
+          @ParametricNullness
           public T next() {
             T result = iterator.next();
             atStart = false; // not called if next() fails
@@ -925,7 +983,8 @@ public Spliterator<T> spliterator() {
    * @throws IllegalArgumentException if {@code limitSize} is negative
    * @since 3.0
    */
-  public static <T> Iterable<T> limit(final Iterable<T> iterable, final int limitSize) {
+  public static <T extends @Nullable Object> Iterable<T> limit(
+      final Iterable<T> iterable, final int limitSize) {
     checkNotNull(iterable);
     checkArgument(limitSize >= 0, "limit is negative");
     return new FluentIterable<T>() {
@@ -957,7 +1016,8 @@ public Spliterator<T> spliterator() {
    * @see Iterators#consumingIterator(Iterator)
    * @since 2.0
    */
-  public static <T> Iterable<T> consumingIterable(final Iterable<T> iterable) {
+  public static <T extends @Nullable Object> Iterable<T> consumingIterable(
+      final Iterable<T> iterable) {
     checkNotNull(iterable);
 
     return new FluentIterable<T>() {
@@ -1009,7 +1069,7 @@ public static boolean isEmpty(Iterable<?> iterable) {
    * @since 11.0
    */
   @Beta
-  public static <T> Iterable<T> mergeSorted(
+  public static <T extends @Nullable Object> Iterable<T> mergeSorted(
       final Iterable<? extends Iterable<? extends T>> iterables,
       final Comparator<? super T> comparator) {
     checkNotNull(iterables, "iterables");
@@ -1027,7 +1087,8 @@ public Iterator<T> iterator() {
 
   // TODO(user): Is this the best place for this? Move to fluent functions?
   // Useful as a public method?
-  static <T> Function<Iterable<? extends T>, Iterator<? extends T>> toIterator() {
+  static <T extends @Nullable Object>
+      Function<Iterable<? extends T>, Iterator<? extends T>> toIterator() {
     return new Function<Iterable<? extends T>, Iterator<? extends T>>() {
       @Override
       public Iterator<? extends T> apply(Iterable<? extends T> iterable) {
diff --git a/guava/src/com/google/common/collect/Iterators.java b/guava/src/com/google/common/collect/Iterators.java
index d2b785f933d7..ea9a4193183c 100644
--- a/guava/src/com/google/common/collect/Iterators.java
+++ b/guava/src/com/google/common/collect/Iterators.java
@@ -21,6 +21,8 @@
 import static com.google.common.base.Preconditions.checkState;
 import static com.google.common.base.Predicates.instanceOf;
 import static com.google.common.collect.CollectPreconditions.checkRemove;
+import static com.google.common.collect.NullnessCasts.uncheckedCastNullableTToT;
+import static java.util.Objects.requireNonNull;
 
 import com.google.common.annotations.Beta;
 import com.google.common.annotations.GwtCompatible;
@@ -45,6 +47,7 @@
 import java.util.NoSuchElementException;
 import java.util.PriorityQueue;
 import java.util.Queue;
+import javax.annotation.CheckForNull;
 import org.checkerframework.checker.nullness.qual.Nullable;
 import org.checkerframework.dataflow.qual.Pure;
 import org.checkerframework.framework.qual.AnnotatedFor;
@@ -59,7 +62,7 @@
  * necessary.
  *
  * <p>See the Guava User Guide section on <a href=
- * "https://github.com/google/guava/wiki/CollectionUtilitiesExplained#iterables"> {@code
+ * "https://github.com/google/guava/wiki/CollectionUtilitiesExplained#iterables">{@code
  * Iterators}</a>.
  *
  * @author Kevin Bourrillion
@@ -68,6 +71,7 @@
  */
 @AnnotatedFor({"nullness"})
 @GwtCompatible(emulated = true)
+@ElementTypesAreNonnullByDefault
 public final class Iterators {
   private Iterators() {}
 
@@ -76,7 +80,7 @@ private Iterators() {}
    *
    * <p>The {@link Iterable} equivalent of this method is {@link ImmutableSet#of()}.
    */
-  static <T> UnmodifiableIterator<T> emptyIterator() {
+  static <T extends @Nullable Object> UnmodifiableIterator<T> emptyIterator() {
     return emptyListIterator();
   }
 
@@ -87,7 +91,7 @@ static <T> UnmodifiableIterator<T> emptyIterator() {
    */
   // Casting to any type is safe since there are no actual elements.
   @SuppressWarnings("unchecked")
-  static <T> UnmodifiableListIterator<T> emptyListIterator() {
+  static <T extends @Nullable Object> UnmodifiableListIterator<T> emptyListIterator() {
     return (UnmodifiableListIterator<T>) ArrayItr.EMPTY;
   }
 
@@ -120,13 +124,13 @@ public void remove() {
    */
   // Casting to any type is safe since there are no actual elements.
   @SuppressWarnings("unchecked")
-  static <T> Iterator<T> emptyModifiableIterator() {
+  static <T extends @Nullable Object> Iterator<T> emptyModifiableIterator() {
     return (Iterator<T>) EmptyModifiableIterator.INSTANCE;
   }
 
   /** Returns an unmodifiable view of {@code iterator}. */
-  public static <T> UnmodifiableIterator<T> unmodifiableIterator(
-      final Iterator<? extends T> iterator) {
+  public static <T extends @Nullable Object> UnmodifiableIterator<T> unmodifiableIterator(
+      Iterator<? extends T> iterator) {
     checkNotNull(iterator);
     if (iterator instanceof UnmodifiableIterator) {
       @SuppressWarnings("unchecked") // Since it's unmodifiable, the covariant cast is safe
@@ -140,6 +144,7 @@ public boolean hasNext() {
       }
 
       @Override
+      @ParametricNullness
       public T next() {
         return iterator.next();
       }
@@ -153,7 +158,8 @@ public T next() {
    * @since 10.0
    */
   @Deprecated
-  public static <T> UnmodifiableIterator<T> unmodifiableIterator(UnmodifiableIterator<T> iterator) {
+  public static <T extends @Nullable Object> UnmodifiableIterator<T> unmodifiableIterator(
+      UnmodifiableIterator<T> iterator) {
     return checkNotNull(iterator);
   }
 
@@ -172,7 +178,7 @@ public static int size(Iterator<?> iterator) {
 
   /** Returns {@code true} if {@code iterator} contains {@code element}. */
   @Pure
-  public static boolean contains(Iterator<?> iterator, @Nullable Object element) {
+  public static boolean contains(Iterator<?> iterator, @CheckForNull Object element) {
     if (element == null) {
       while (iterator.hasNext()) {
         if (iterator.next() == null) {
@@ -220,7 +226,8 @@ public static boolean removeAll(Iterator<?> removeFrom, Collection<?> elementsTo
    * @since 2.0
    */
   @CanIgnoreReturnValue
-  public static <T> boolean removeIf(Iterator<T> removeFrom, Predicate<? super T> predicate) {
+  public static <T extends @Nullable Object> boolean removeIf(
+      Iterator<T> removeFrom, Predicate<? super T> predicate) {
     checkNotNull(predicate);
     boolean modified = false;
     while (removeFrom.hasNext()) {
@@ -302,7 +309,8 @@ public static String toString(Iterator<?> iterator) {
    * @throws IllegalArgumentException if the iterator contains multiple elements. The state of the
    *     iterator is unspecified.
    */
-  public static <T> T getOnlyElement(Iterator<T> iterator) {
+  @ParametricNullness
+  public static <T extends @Nullable Object> T getOnlyElement(Iterator<T> iterator) {
     T first = iterator.next();
     if (!iterator.hasNext()) {
       return first;
@@ -327,8 +335,9 @@ public static <T> T getOnlyElement(Iterator<T> iterator) {
    * @throws IllegalArgumentException if the iterator contains multiple elements. The state of the
    *     iterator is unspecified.
    */
-  public static <T> @Nullable T getOnlyElement(
-      Iterator<? extends T> iterator, @Nullable T defaultValue) {
+  @ParametricNullness
+  public static <T extends @Nullable Object> T getOnlyElement(
+      Iterator<? extends T> iterator, @ParametricNullness T defaultValue) {
     return iterator.hasNext() ? getOnlyElement(iterator) : defaultValue;
   }
 
@@ -341,8 +350,9 @@ public static <T> T getOnlyElement(Iterator<T> iterator) {
    * @return a newly-allocated array into which all the elements of the iterator have been copied
    */
   @GwtIncompatible // Array.newInstance(Class, int)
-  public static <T> T[] toArray(Iterator<? extends T> iterator, Class<T> type) {
-    List<T> list = Lists.newArrayList(iterator);
+  // For discussion of this signature, see the corresponding overload of *Iterables*.toArray.
+  public static <T> @Nullable T[] toArray(Iterator<? extends @Nullable T> iterator, Class<T> type) {
+    List<@Nullable T> list = Lists.newArrayList(iterator);
     return Iterables.toArray(list, type);
   }
 
@@ -353,7 +363,8 @@ public static <T> T[] toArray(Iterator<? extends T> iterator, Class<T> type) {
    * @return {@code true} if {@code collection} was modified as a result of this operation
    */
   @CanIgnoreReturnValue
-  public static <T> boolean addAll(Collection<T> addTo, Iterator<? extends T> iterator) {
+  public static <T extends @Nullable Object> boolean addAll(
+      Collection<T> addTo, Iterator<? extends T> iterator) {
     checkNotNull(addTo);
     checkNotNull(iterator);
     boolean wasModified = false;
@@ -369,7 +380,7 @@ public static <T> boolean addAll(Collection<T> addTo, Iterator<? extends T> iter
    *
    * @see Collections#frequency
    */
-  public static int frequency(Iterator<?> iterator, @Nullable Object element) {
+  public static int frequency(Iterator<?> iterator, @CheckForNull Object element) {
     int count = 0;
     while (contains(iterator, element)) {
       // Since it lives in the same class, we know contains gets to the element and then stops,
@@ -391,7 +402,7 @@ public static int frequency(Iterator<?> iterator, @Nullable Object element) {
    * should use an explicit {@code break} or be certain that you will eventually remove all the
    * elements.
    */
-  public static <T> Iterator<T> cycle(final Iterable<T> iterable) {
+  public static <T extends @Nullable Object> Iterator<T> cycle(Iterable<T> iterable) {
     checkNotNull(iterable);
     return new Iterator<T>() {
       Iterator<T> iterator = emptyModifiableIterator();
@@ -411,6 +422,7 @@ public boolean hasNext() {
       }
 
       @Override
+      @ParametricNullness
       public T next() {
         if (!iterator.hasNext()) {
           iterator = iterable.iterator();
@@ -441,7 +453,7 @@ public void remove() {
    * elements.
    */
   @SafeVarargs
-  public static <T> Iterator<T> cycle(T... elements) {
+  public static <T extends @Nullable Object> Iterator<T> cycle(T... elements) {
     return cycle(Lists.newArrayList(elements));
   }
 
@@ -449,10 +461,14 @@ public static <T> Iterator<T> cycle(T... elements) {
    * Returns an Iterator that walks the specified array, nulling out elements behind it. This can
    * avoid memory leaks when an element is no longer necessary.
    *
+   * <p>This method accepts an array with element type {@code @Nullable T}, but callers must pass an
+   * array whose contents are initially non-null. The {@code @Nullable} annotation indicates that
+   * this method will write nulls into the array during iteration.
+   *
    * <p>This is mainly just to avoid the intermediate ArrayDeque in ConsumingQueueIterator.
    */
-  private static <T> Iterator<T> consumingForArray(final T... elements) {
-    return new UnmodifiableIterator<T>() {
+  private static <I extends Iterator<?>> Iterator<I> consumingForArray(@Nullable I... elements) {
+    return new UnmodifiableIterator<I>() {
       int index = 0;
 
       @Override
@@ -461,11 +477,15 @@ public boolean hasNext() {
       }
 
       @Override
-      public T next() {
+      public I next() {
         if (!hasNext()) {
           throw new NoSuchElementException();
         }
-        T result = elements[index];
+        /*
+         * requireNonNull is safe because our callers always pass non-null arguments. Each element
+         * of the array becomes null only when we iterate past it and then clear it.
+         */
+        I result = requireNonNull(elements[index]);
         elements[index] = null;
         index++;
         return result;
@@ -481,7 +501,8 @@ public T next() {
    * <p>The returned iterator supports {@code remove()} when the corresponding input iterator
    * supports it.
    */
-  public static <T> Iterator<T> concat(Iterator<? extends T> a, Iterator<? extends T> b) {
+  public static <T extends @Nullable Object> Iterator<T> concat(
+      Iterator<? extends T> a, Iterator<? extends T> b) {
     checkNotNull(a);
     checkNotNull(b);
     return concat(consumingForArray(a, b));
@@ -495,7 +516,7 @@ public static <T> Iterator<T> concat(Iterator<? extends T> a, Iterator<? extends
    * <p>The returned iterator supports {@code remove()} when the corresponding input iterator
    * supports it.
    */
-  public static <T> Iterator<T> concat(
+  public static <T extends @Nullable Object> Iterator<T> concat(
       Iterator<? extends T> a, Iterator<? extends T> b, Iterator<? extends T> c) {
     checkNotNull(a);
     checkNotNull(b);
@@ -512,7 +533,7 @@ public static <T> Iterator<T> concat(
    * <p>The returned iterator supports {@code remove()} when the corresponding input iterator
    * supports it.
    */
-  public static <T> Iterator<T> concat(
+  public static <T extends @Nullable Object> Iterator<T> concat(
       Iterator<? extends T> a,
       Iterator<? extends T> b,
       Iterator<? extends T> c,
@@ -534,7 +555,7 @@ public static <T> Iterator<T> concat(
    *
    * @throws NullPointerException if any of the provided iterators is null
    */
-  public static <T> Iterator<T> concat(Iterator<? extends T>... inputs) {
+  public static <T extends @Nullable Object> Iterator<T> concat(Iterator<? extends T>... inputs) {
     return concatNoDefensiveCopy(Arrays.copyOf(inputs, inputs.length));
   }
 
@@ -547,12 +568,14 @@ public static <T> Iterator<T> concat(Iterator<? extends T>... inputs) {
    * supports it. The methods of the returned iterator may throw {@code NullPointerException} if any
    * of the input iterators is null.
    */
-  public static <T> Iterator<T> concat(Iterator<? extends Iterator<? extends T>> inputs) {
-    return new ConcatenatedIterator<T>(inputs);
+  public static <T extends @Nullable Object> Iterator<T> concat(
+      Iterator<? extends Iterator<? extends T>> inputs) {
+    return new ConcatenatedIterator<>(inputs);
   }
 
   /** Concats a varargs array of iterators without making a defensive copy of the array. */
-  static <T> Iterator<T> concatNoDefensiveCopy(Iterator<? extends T>... inputs) {
+  static <T extends @Nullable Object> Iterator<T> concatNoDefensiveCopy(
+      Iterator<? extends T>... inputs) {
     for (Iterator<? extends T> input : checkNotNull(inputs)) {
       checkNotNull(input);
     }
@@ -567,13 +590,18 @@ static <T> Iterator<T> concatNoDefensiveCopy(Iterator<? extends T>... inputs) {
    *
    * <p>The returned lists implement {@link java.util.RandomAccess}.
    *
+   * <p><b>Note:</b> The current implementation eagerly allocates storage for {@code size} elements.
+   * As a consequence, passing values like {@code Integer.MAX_VALUE} can lead to {@link
+   * OutOfMemoryError}.
+   *
    * @param iterator the iterator to return a partitioned view of
    * @param size the desired size of each partition (the last may be smaller)
    * @return an iterator of immutable lists containing the elements of {@code iterator} divided into
    *     partitions
    * @throws IllegalArgumentException if {@code size} is nonpositive
    */
-  public static <T> UnmodifiableIterator<List<T>> partition(Iterator<T> iterator, int size) {
+  public static <T extends @Nullable Object> UnmodifiableIterator<List<T>> partition(
+      Iterator<T> iterator, int size) {
     return partitionImpl(iterator, size, false);
   }
 
@@ -591,26 +619,29 @@ public static <T> UnmodifiableIterator<List<T>> partition(Iterator<T> iterator,
    *     partitions (the final iterable may have trailing null elements)
    * @throws IllegalArgumentException if {@code size} is nonpositive
    */
-  public static <T> UnmodifiableIterator<List<T>> paddedPartition(Iterator<T> iterator, int size) {
+  public static <T extends @Nullable Object>
+      UnmodifiableIterator<List<@Nullable T>> paddedPartition(Iterator<T> iterator, int size) {
     return partitionImpl(iterator, size, true);
   }
 
-  private static <T> UnmodifiableIterator<List<T>> partitionImpl(
-      final Iterator<T> iterator, final int size, final boolean pad) {
+  private static <T extends @Nullable Object> UnmodifiableIterator<List<@Nullable T>> partitionImpl(
+      Iterator<T> iterator, int size, boolean pad) {
     checkNotNull(iterator);
     checkArgument(size > 0);
-    return new UnmodifiableIterator<List<T>>() {
+    return new UnmodifiableIterator<List<@Nullable T>>() {
       @Override
       public boolean hasNext() {
         return iterator.hasNext();
       }
 
       @Override
-      public List<T> next() {
+      public List<@Nullable T> next() {
         if (!hasNext()) {
           throw new NoSuchElementException();
         }
-        @Nullable Object[] array = new Object[size];
+        @SuppressWarnings("unchecked") // we only put Ts in it
+        @Nullable
+        T[] array = (@Nullable T[]) new Object[size];
         int count = 0;
         for (; count < size && iterator.hasNext(); count++) {
           array[count] = iterator.next();
@@ -619,9 +650,13 @@ public List<T> next() {
           array[i] = null; // for GWT
         }
 
-        @SuppressWarnings("unchecked") // we only put Ts in it
-        List<T> list = Collections.unmodifiableList((List<T>) Arrays.asList(array));
-        return (pad || count == size) ? list : list.subList(0, count);
+        List<@Nullable T> list = Collections.unmodifiableList(Arrays.asList(array));
+        // TODO(b/192579700): Use a ternary once it no longer confuses our nullness checker.
+        if (pad || count == size) {
+          return list;
+        } else {
+          return list.subList(0, count);
+        }
       }
     };
   }
@@ -630,12 +665,13 @@ public List<T> next() {
    * Returns a view of {@code unfiltered} containing all elements that satisfy the input predicate
    * {@code retainIfTrue}.
    */
-  public static <T> UnmodifiableIterator<T> filter(
-      final Iterator<T> unfiltered, final Predicate<? super T> retainIfTrue) {
+  public static <T extends @Nullable Object> UnmodifiableIterator<T> filter(
+      Iterator<T> unfiltered, Predicate<? super T> retainIfTrue) {
     checkNotNull(unfiltered);
     checkNotNull(retainIfTrue);
     return new AbstractIterator<T>() {
       @Override
+      @CheckForNull
       protected T computeNext() {
         while (unfiltered.hasNext()) {
           T element = unfiltered.next();
@@ -662,7 +698,8 @@ public static <T> UnmodifiableIterator<T> filter(Iterator<?> unfiltered, Class<T
    * Returns {@code true} if one or more elements returned by {@code iterator} satisfy the given
    * predicate.
    */
-  public static <T> boolean any(Iterator<T> iterator, Predicate<? super T> predicate) {
+  public static <T extends @Nullable Object> boolean any(
+      Iterator<T> iterator, Predicate<? super T> predicate) {
     return indexOf(iterator, predicate) != -1;
   }
 
@@ -670,7 +707,8 @@ public static <T> boolean any(Iterator<T> iterator, Predicate<? super T> predica
    * Returns {@code true} if every element returned by {@code iterator} satisfies the given
    * predicate. If {@code iterator} is empty, {@code true} is returned.
    */
-  public static <T> boolean all(Iterator<T> iterator, Predicate<? super T> predicate) {
+  public static <T extends @Nullable Object> boolean all(
+      Iterator<T> iterator, Predicate<? super T> predicate) {
     checkNotNull(predicate);
     while (iterator.hasNext()) {
       T element = iterator.next();
@@ -690,7 +728,9 @@ public static <T> boolean all(Iterator<T> iterator, Predicate<? super T> predica
    *
    * @throws NoSuchElementException if no element in {@code iterator} matches the given predicate
    */
-  public static <T> T find(Iterator<T> iterator, Predicate<? super T> predicate) {
+  @ParametricNullness
+  public static <T extends @Nullable Object> T find(
+      Iterator<T> iterator, Predicate<? super T> predicate) {
     checkNotNull(iterator);
     checkNotNull(predicate);
     while (iterator.hasNext()) {
@@ -710,8 +750,12 @@ public static <T> T find(Iterator<T> iterator, Predicate<? super T> predicate) {
    *
    * @since 7.0
    */
-  public static <T> @Nullable T find(
-      Iterator<? extends T> iterator, Predicate<? super T> predicate, @Nullable T defaultValue) {
+  // For discussion of this signature, see the corresponding overload of *Iterables*.find.
+  @CheckForNull
+  public static <T extends @Nullable Object> T find(
+      Iterator<? extends T> iterator,
+      Predicate<? super T> predicate,
+      @CheckForNull T defaultValue) {
     checkNotNull(iterator);
     checkNotNull(predicate);
     while (iterator.hasNext()) {
@@ -760,7 +804,8 @@ public static <T> Optional<T> tryFind(Iterator<T> iterator, Predicate<? super T>
    *
    * @since 2.0
    */
-  public static <T> int indexOf(Iterator<T> iterator, Predicate<? super T> predicate) {
+  public static <T extends @Nullable Object> int indexOf(
+      Iterator<T> iterator, Predicate<? super T> predicate) {
     checkNotNull(predicate, "predicate");
     for (int i = 0; iterator.hasNext(); i++) {
       T current = iterator.next();
@@ -779,12 +824,13 @@ public static <T> int indexOf(Iterator<T> iterator, Predicate<? super T> predica
    * successful {@code remove()} call, {@code fromIterator} no longer contains the corresponding
    * element.
    */
-  public static <F, T> Iterator<T> transform(
-      final Iterator<F> fromIterator, final Function<? super F, ? extends T> function) {
+  public static <F extends @Nullable Object, T extends @Nullable Object> Iterator<T> transform(
+      Iterator<F> fromIterator, Function<? super F, ? extends T> function) {
     checkNotNull(function);
     return new TransformedIterator<F, T>(fromIterator) {
+      @ParametricNullness
       @Override
-      T transform(F from) {
+      T transform(@ParametricNullness F from) {
         return function.apply(from);
       }
     };
@@ -799,7 +845,8 @@ T transform(F from) {
    * @throws IndexOutOfBoundsException if {@code position} is negative or greater than or equal to
    *     the number of elements remaining in {@code iterator}
    */
-  public static <T> T get(Iterator<T> iterator, int position) {
+  @ParametricNullness
+  public static <T extends @Nullable Object> T get(Iterator<T> iterator, int position) {
     checkNonnegative(position);
     int skipped = advance(iterator, position);
     if (!iterator.hasNext()) {
@@ -825,8 +872,9 @@ public static <T> T get(Iterator<T> iterator, int position) {
    * @throws IndexOutOfBoundsException if {@code position} is negative
    * @since 4.0
    */
-  public static <T> @Nullable T get(
-      Iterator<? extends T> iterator, int position, @Nullable T defaultValue) {
+  @ParametricNullness
+  public static <T extends @Nullable Object> T get(
+      Iterator<? extends T> iterator, int position, @ParametricNullness T defaultValue) {
     checkNonnegative(position);
     advance(iterator, position);
     return getNext(iterator, defaultValue);
@@ -846,7 +894,9 @@ static void checkNonnegative(int position) {
    * @return the next element of {@code iterator} or the default value
    * @since 7.0
    */
-  public static <T> @Nullable T getNext(Iterator<? extends T> iterator, @Nullable T defaultValue) {
+  @ParametricNullness
+  public static <T extends @Nullable Object> T getNext(
+      Iterator<? extends T> iterator, @ParametricNullness T defaultValue) {
     return iterator.hasNext() ? iterator.next() : defaultValue;
   }
 
@@ -856,7 +906,8 @@ static void checkNonnegative(int position) {
    * @return the last element of {@code iterator}
    * @throws NoSuchElementException if the iterator is empty
    */
-  public static <T> T getLast(Iterator<T> iterator) {
+  @ParametricNullness
+  public static <T extends @Nullable Object> T getLast(Iterator<T> iterator) {
     while (true) {
       T current = iterator.next();
       if (!iterator.hasNext()) {
@@ -873,7 +924,9 @@ public static <T> T getLast(Iterator<T> iterator) {
    * @return the last element of {@code iterator}
    * @since 3.0
    */
-  public static <T> @Nullable T getLast(Iterator<? extends T> iterator, @Nullable T defaultValue) {
+  @ParametricNullness
+  public static <T extends @Nullable Object> T getLast(
+      Iterator<? extends T> iterator, @ParametricNullness T defaultValue) {
     return iterator.hasNext() ? getLast(iterator) : defaultValue;
   }
 
@@ -906,7 +959,8 @@ public static int advance(Iterator<?> iterator, int numberToAdvance) {
    * @throws IllegalArgumentException if {@code limitSize} is negative
    * @since 3.0
    */
-  public static <T> Iterator<T> limit(final Iterator<T> iterator, final int limitSize) {
+  public static <T extends @Nullable Object> Iterator<T> limit(
+      Iterator<T> iterator, int limitSize) {
     checkNotNull(iterator);
     checkArgument(limitSize >= 0, "limit is negative");
     return new Iterator<T>() {
@@ -918,6 +972,7 @@ public boolean hasNext() {
       }
 
       @Override
+      @ParametricNullness
       public T next() {
         if (!hasNext()) {
           throw new NoSuchElementException();
@@ -944,7 +999,7 @@ public void remove() {
    * @return an iterator that removes and returns elements from the supplied iterator
    * @since 2.0
    */
-  public static <T> Iterator<T> consumingIterator(final Iterator<T> iterator) {
+  public static <T extends @Nullable Object> Iterator<T> consumingIterator(Iterator<T> iterator) {
     checkNotNull(iterator);
     return new UnmodifiableIterator<T>() {
       @Override
@@ -953,6 +1008,7 @@ public boolean hasNext() {
       }
 
       @Override
+      @ParametricNullness
       public T next() {
         T next = iterator.next();
         iterator.remove();
@@ -970,7 +1026,8 @@ public String toString() {
    * Deletes and returns the next value from the iterator, or returns {@code null} if there is no
    * such value.
    */
-  static <T> @Nullable T pollNext(Iterator<T> iterator) {
+  @CheckForNull
+  static <T extends @Nullable Object> T pollNext(Iterator<T> iterator) {
     if (iterator.hasNext()) {
       T result = iterator.next();
       iterator.remove();
@@ -1002,7 +1059,7 @@ static void clear(Iterator<?> iterator) {
    * {@link ImmutableList#copyOf(Object[])}}, or {@link ImmutableList#of}.
    */
   @SafeVarargs
-  public static <T> UnmodifiableIterator<T> forArray(final T... array) {
+  public static <T extends @Nullable Object> UnmodifiableIterator<T> forArray(T... array) {
     return forArray(array, 0, array.length, 0);
   }
 
@@ -1013,8 +1070,8 @@ public static <T> UnmodifiableIterator<T> forArray(final T... array) {
    * <p>The {@code Iterable} equivalent of this method is {@code
    * Arrays.asList(array).subList(offset, offset + length).listIterator(index)}.
    */
-  static <T> UnmodifiableListIterator<T> forArray(
-      final T[] array, final int offset, int length, int index) {
+  static <T extends @Nullable Object> UnmodifiableListIterator<T> forArray(
+      T[] array, int offset, int length, int index) {
     checkArgument(length >= 0);
     int end = offset + length;
 
@@ -1024,10 +1081,11 @@ static <T> UnmodifiableListIterator<T> forArray(
     if (length == 0) {
       return emptyListIterator();
     }
-    return new ArrayItr<T>(array, offset, length, index);
+    return new ArrayItr<>(array, offset, length, index);
   }
 
-  private static final class ArrayItr<T> extends AbstractIndexedListIterator<T> {
+  private static final class ArrayItr<T extends @Nullable Object>
+      extends AbstractIndexedListIterator<T> {
     static final UnmodifiableListIterator<Object> EMPTY = new ArrayItr<>(new Object[0], 0, 0, 0);
 
     private final T[] array;
@@ -1040,6 +1098,7 @@ private static final class ArrayItr<T> extends AbstractIndexedListIterator<T> {
     }
 
     @Override
+    @ParametricNullness
     protected T get(int index) {
       return array[offset + index];
     }
@@ -1050,7 +1109,8 @@ protected T get(int index) {
    *
    * <p>The {@link Iterable} equivalent of this method is {@link Collections#singleton}.
    */
-  public static <T> UnmodifiableIterator<T> singletonIterator(final @Nullable T value) {
+  public static <T extends @Nullable Object> UnmodifiableIterator<T> singletonIterator(
+      @ParametricNullness T value) {
     return new UnmodifiableIterator<T>() {
       boolean done;
 
@@ -1060,6 +1120,7 @@ public boolean hasNext() {
       }
 
       @Override
+      @ParametricNullness
       public T next() {
         if (done) {
           throw new NoSuchElementException();
@@ -1080,7 +1141,8 @@ public T next() {
    * <p><b>Java 9 users:</b> use {@code enumeration.asIterator()} instead, unless it is important to
    * return an {@code UnmodifiableIterator} instead of a plain {@code Iterator}.
    */
-  public static <T> UnmodifiableIterator<T> forEnumeration(final Enumeration<T> enumeration) {
+  public static <T extends @Nullable Object> UnmodifiableIterator<T> forEnumeration(
+      Enumeration<T> enumeration) {
     checkNotNull(enumeration);
     return new UnmodifiableIterator<T>() {
       @Override
@@ -1089,6 +1151,7 @@ public boolean hasNext() {
       }
 
       @Override
+      @ParametricNullness
       public T next() {
         return enumeration.nextElement();
       }
@@ -1101,7 +1164,7 @@ public T next() {
    * <p>The {@code Iterable} equivalent of this method is either {@link Collections#enumeration} (if
    * you have a {@link Collection}), or {@code Iterators.asEnumeration(collection.iterator())}.
    */
-  public static <T> Enumeration<T> asEnumeration(final Iterator<T> iterator) {
+  public static <T extends @Nullable Object> Enumeration<T> asEnumeration(Iterator<T> iterator) {
     checkNotNull(iterator);
     return new Enumeration<T>() {
       @Override
@@ -1110,6 +1173,7 @@ public boolean hasMoreElements() {
       }
 
       @Override
+      @ParametricNullness
       public T nextElement() {
         return iterator.next();
       }
@@ -1117,11 +1181,11 @@ public T nextElement() {
   }
 
   /** Implementation of PeekingIterator that avoids peeking unless necessary. */
-  private static class PeekingImpl<E> implements PeekingIterator<E> {
+  private static class PeekingImpl<E extends @Nullable Object> implements PeekingIterator<E> {
 
     private final Iterator<? extends E> iterator;
     private boolean hasPeeked;
-    private @Nullable E peekedElement;
+    @CheckForNull private E peekedElement;
 
     public PeekingImpl(Iterator<? extends E> iterator) {
       this.iterator = checkNotNull(iterator);
@@ -1133,11 +1197,13 @@ public boolean hasNext() {
     }
 
     @Override
+    @ParametricNullness
     public E next() {
       if (!hasPeeked) {
         return iterator.next();
       }
-      E result = peekedElement;
+      // The cast is safe because of the hasPeeked check.
+      E result = uncheckedCastNullableTToT(peekedElement);
       hasPeeked = false;
       peekedElement = null;
       return result;
@@ -1150,12 +1216,14 @@ public void remove() {
     }
 
     @Override
+    @ParametricNullness
     public E peek() {
       if (!hasPeeked) {
         peekedElement = iterator.next();
         hasPeeked = true;
       }
-      return peekedElement;
+      // The cast is safe because of the hasPeeked check.
+      return uncheckedCastNullableTToT(peekedElement);
     }
   }
 
@@ -1195,7 +1263,8 @@ public E peek() {
    * @return a peeking iterator backed by that iterator. Apart from the additional {@link
    *     PeekingIterator#peek()} method, this iterator behaves exactly the same as {@code iterator}.
    */
-  public static <T> PeekingIterator<T> peekingIterator(Iterator<? extends T> iterator) {
+  public static <T extends @Nullable Object> PeekingIterator<T> peekingIterator(
+      Iterator<? extends T> iterator) {
     if (iterator instanceof PeekingImpl) {
       // Safe to cast <? extends T> to <T> because PeekingImpl only uses T
       // covariantly (and cannot be subclassed to add non-covariant uses).
@@ -1203,7 +1272,7 @@ public static <T> PeekingIterator<T> peekingIterator(Iterator<? extends T> itera
       PeekingImpl<T> peeking = (PeekingImpl<T>) iterator;
       return peeking;
     }
-    return new PeekingImpl<T>(iterator);
+    return new PeekingImpl<>(iterator);
   }
 
   /**
@@ -1213,7 +1282,8 @@ public static <T> PeekingIterator<T> peekingIterator(Iterator<? extends T> itera
    * @since 10.0
    */
   @Deprecated
-  public static <T> PeekingIterator<T> peekingIterator(PeekingIterator<T> iterator) {
+  public static <T extends @Nullable Object> PeekingIterator<T> peekingIterator(
+      PeekingIterator<T> iterator) {
     return checkNotNull(iterator);
   }
 
@@ -1230,12 +1300,12 @@ public static <T> PeekingIterator<T> peekingIterator(PeekingIterator<T> iterator
    * @since 11.0
    */
   @Beta
-  public static <T> UnmodifiableIterator<T> mergeSorted(
+  public static <T extends @Nullable Object> UnmodifiableIterator<T> mergeSorted(
       Iterable<? extends Iterator<? extends T>> iterators, Comparator<? super T> comparator) {
     checkNotNull(iterators, "iterators");
     checkNotNull(comparator, "comparator");
 
-    return new MergingIterator<T>(iterators, comparator);
+    return new MergingIterator<>(iterators, comparator);
   }
 
   /**
@@ -1247,21 +1317,16 @@ public static <T> UnmodifiableIterator<T> mergeSorted(
    * iterators. (Retrieving all elements takes approximately O(N*log(M)) time, where N is the total
    * number of elements.)
    */
-  private static class MergingIterator<T> extends UnmodifiableIterator<T> {
+  private static class MergingIterator<T extends @Nullable Object> extends UnmodifiableIterator<T> {
     final Queue<PeekingIterator<T>> queue;
 
     public MergingIterator(
-        Iterable<? extends Iterator<? extends T>> iterators,
-        final Comparator<? super T> itemComparator) {
+        Iterable<? extends Iterator<? extends T>> iterators, Comparator<? super T> itemComparator) {
       // A comparator that's used by the heap, allowing the heap
       // to be sorted based on the top of each iterator.
       Comparator<PeekingIterator<T>> heapComparator =
-          new Comparator<PeekingIterator<T>>() {
-            @Override
-            public int compare(PeekingIterator<T> o1, PeekingIterator<T> o2) {
-              return itemComparator.compare(o1.peek(), o2.peek());
-            }
-          };
+          (PeekingIterator<T> o1, PeekingIterator<T> o2) ->
+              itemComparator.compare(o1.peek(), o2.peek());
 
       queue = new PriorityQueue<>(2, heapComparator);
 
@@ -1278,6 +1343,7 @@ public boolean hasNext() {
     }
 
     @Override
+    @ParametricNullness
     public T next() {
       PeekingIterator<T> nextIter = queue.remove();
       T next = nextIter.next();
@@ -1288,9 +1354,9 @@ public T next() {
     }
   }
 
-  private static class ConcatenatedIterator<T> implements Iterator<T> {
+  private static class ConcatenatedIterator<T extends @Nullable Object> implements Iterator<T> {
     /* The last iterator to return an element.  Calls to remove() go to this iterator. */
-    private @Nullable Iterator<? extends T> toRemove;
+    @CheckForNull private Iterator<? extends T> toRemove;
 
     /* The iterator currently returning elements. */
     private Iterator<? extends T> iterator;
@@ -1302,10 +1368,10 @@ private static class ConcatenatedIterator<T> implements Iterator<T> {
      * operation O(1).
      */
 
-    private Iterator<? extends Iterator<? extends T>> topMetaIterator;
+    @CheckForNull private Iterator<? extends Iterator<? extends T>> topMetaIterator;
 
     // Only becomes nonnull if we encounter nested concatenations.
-    private @Nullable Deque<Iterator<? extends Iterator<? extends T>>> metaIterators;
+    @CheckForNull private Deque<Iterator<? extends Iterator<? extends T>>> metaIterators;
 
     ConcatenatedIterator(Iterator<? extends Iterator<? extends T>> metaIterator) {
       iterator = emptyIterator();
@@ -1313,7 +1379,8 @@ private static class ConcatenatedIterator<T> implements Iterator<T> {
     }
 
     // Returns a nonempty meta-iterator or, if all meta-iterators are empty, null.
-    private @Nullable Iterator<? extends Iterator<? extends T>> getTopMetaIterator() {
+    @CheckForNull
+    private Iterator<? extends Iterator<? extends T>> getTopMetaIterator() {
       while (topMetaIterator == null || !topMetaIterator.hasNext()) {
         if (metaIterators != null && !metaIterators.isEmpty()) {
           topMetaIterator = metaIterators.removeFirst();
@@ -1363,6 +1430,7 @@ public boolean hasNext() {
     }
 
     @Override
+    @ParametricNullness
     public T next() {
       if (hasNext()) {
         toRemove = iterator;
@@ -1374,14 +1442,16 @@ public T next() {
 
     @Override
     public void remove() {
-      CollectPreconditions.checkRemove(toRemove != null);
+      if (toRemove == null) {
+        throw new IllegalStateException("no calls to next() since the last call to remove()");
+      }
       toRemove.remove();
       toRemove = null;
     }
   }
 
   /** Used to avoid http://bugs.sun.com/view_bug.do?bug_id=6558557 */
-  static <T> ListIterator<T> cast(Iterator<T> iterator) {
+  static <T extends @Nullable Object> ListIterator<T> cast(Iterator<T> iterator) {
     return (ListIterator<T>) iterator;
   }
 }
diff --git a/guava/src/com/google/common/collect/JdkBackedImmutableBiMap.java b/guava/src/com/google/common/collect/JdkBackedImmutableBiMap.java
index 6fceaa91f2bf..f126fdea3baf 100644
--- a/guava/src/com/google/common/collect/JdkBackedImmutableBiMap.java
+++ b/guava/src/com/google/common/collect/JdkBackedImmutableBiMap.java
@@ -15,12 +15,15 @@
  */
 package com.google.common.collect;
 
+import static java.util.Objects.requireNonNull;
+
 import com.google.common.annotations.GwtCompatible;
 import com.google.common.annotations.VisibleForTesting;
 import com.google.errorprone.annotations.concurrent.LazyInit;
 import com.google.j2objc.annotations.RetainedWith;
 import com.google.j2objc.annotations.WeakOuter;
 import java.util.Map;
+import javax.annotation.CheckForNull;
 import org.checkerframework.checker.nullness.qual.Nullable;
 
 /**
@@ -28,13 +31,15 @@
  * protecting against hash flooding.
  */
 @GwtCompatible(emulated = true)
+@ElementTypesAreNonnullByDefault
 final class JdkBackedImmutableBiMap<K, V> extends ImmutableBiMap<K, V> {
   @VisibleForTesting
-  static <K, V> ImmutableBiMap<K, V> create(int n, Entry<K, V>[] entryArray) {
+  static <K, V> ImmutableBiMap<K, V> create(int n, @Nullable Entry<K, V>[] entryArray) {
     Map<K, V> forwardDelegate = Maps.newHashMapWithExpectedSize(n);
     Map<V, K> backwardDelegate = Maps.newHashMapWithExpectedSize(n);
     for (int i = 0; i < n; i++) {
-      Entry<K, V> e = RegularImmutableMap.makeImmutable(entryArray[i]);
+      // requireNonNull is safe because the first `n` elements have been filled in.
+      Entry<K, V> e = RegularImmutableMap.makeImmutable(requireNonNull(entryArray[i]));
       entryArray[i] = e;
       V oldValue = forwardDelegate.putIfAbsent(e.getKey(), e.getValue());
       if (oldValue != null) {
@@ -65,7 +70,7 @@ public int size() {
     return entries.size();
   }
 
-  @LazyInit @RetainedWith private transient JdkBackedImmutableBiMap<V, K> inverse;
+  @LazyInit @RetainedWith @CheckForNull private transient JdkBackedImmutableBiMap<V, K> inverse;
 
   @Override
   public ImmutableBiMap<V, K> inverse() {
@@ -73,7 +78,7 @@ public ImmutableBiMap<V, K> inverse() {
     if (result == null) {
       inverse =
           result =
-              new JdkBackedImmutableBiMap<V, K>(
+              new JdkBackedImmutableBiMap<>(
                   new InverseEntries(), backwardDelegate, forwardDelegate);
       result.inverse = this;
     }
@@ -100,18 +105,19 @@ public int size() {
   }
 
   @Override
-  public V get(@Nullable Object key) {
+  @CheckForNull
+  public V get(@CheckForNull Object key) {
     return forwardDelegate.get(key);
   }
 
   @Override
   ImmutableSet<Entry<K, V>> createEntrySet() {
-    return new ImmutableMapEntrySet.RegularEntrySet<K, V>(this, entries);
+    return new ImmutableMapEntrySet.RegularEntrySet<>(this, entries);
   }
 
   @Override
   ImmutableSet<K> createKeySet() {
-    return new ImmutableMapKeySet<K, V>(this);
+    return new ImmutableMapKeySet<>(this);
   }
 
   @Override
diff --git a/guava/src/com/google/common/collect/JdkBackedImmutableMap.java b/guava/src/com/google/common/collect/JdkBackedImmutableMap.java
index ffbd1892aaa7..222c4deb8ae5 100644
--- a/guava/src/com/google/common/collect/JdkBackedImmutableMap.java
+++ b/guava/src/com/google/common/collect/JdkBackedImmutableMap.java
@@ -18,10 +18,13 @@
 
 import static com.google.common.base.Preconditions.checkNotNull;
 import static com.google.common.collect.RegularImmutableMap.makeImmutable;
+import static java.util.Objects.requireNonNull;
 
 import com.google.common.annotations.GwtCompatible;
+import java.util.HashMap;
 import java.util.Map;
 import java.util.function.BiConsumer;
+import javax.annotation.CheckForNull;
 import org.checkerframework.checker.nullness.qual.Nullable;
 
 /**
@@ -29,21 +32,57 @@
  * hash flooding.
  */
 @GwtCompatible(emulated = true)
+@ElementTypesAreNonnullByDefault
 final class JdkBackedImmutableMap<K, V> extends ImmutableMap<K, V> {
   /**
    * Creates an {@code ImmutableMap} backed by a JDK HashMap. Used when probable hash flooding is
    * detected. This implementation may replace the entries in entryArray with its own entry objects
    * (though they will have the same key/value contents), and will take ownership of entryArray.
    */
-  static <K, V> ImmutableMap<K, V> create(int n, Entry<K, V>[] entryArray) {
+  static <K, V> ImmutableMap<K, V> create(
+      int n, @Nullable Entry<K, V>[] entryArray, boolean throwIfDuplicateKeys) {
     Map<K, V> delegateMap = Maps.newHashMapWithExpectedSize(n);
+    // If duplicates are allowed, this map will track the last value for each duplicated key.
+    // A second pass will retain only the first entry for that key, but with this last value. The
+    // value will then be replaced by null, signaling that later entries with the same key should
+    // be deleted.
+    Map<K, @Nullable V> duplicates = null;
+    int dupCount = 0;
     for (int i = 0; i < n; i++) {
-      entryArray[i] = makeImmutable(entryArray[i]);
-      V oldValue = delegateMap.putIfAbsent(entryArray[i].getKey(), entryArray[i].getValue());
+      // requireNonNull is safe because the first `n` elements have been filled in.
+      entryArray[i] = makeImmutable(requireNonNull(entryArray[i]));
+      K key = entryArray[i].getKey();
+      V value = entryArray[i].getValue();
+      V oldValue = delegateMap.put(key, value);
       if (oldValue != null) {
-        throw conflictException("key", entryArray[i], entryArray[i].getKey() + "=" + oldValue);
+        if (throwIfDuplicateKeys) {
+          throw conflictException("key", entryArray[i], entryArray[i].getKey() + "=" + oldValue);
+        }
+        if (duplicates == null) {
+          duplicates = new HashMap<>();
+        }
+        duplicates.put(key, value);
+        dupCount++;
       }
     }
+    if (duplicates != null) {
+      @SuppressWarnings({"rawtypes", "unchecked"})
+      Entry<K, V>[] newEntryArray = new Entry[n - dupCount];
+      for (int inI = 0, outI = 0; inI < n; inI++) {
+        Entry<K, V> entry = requireNonNull(entryArray[inI]);
+        K key = entry.getKey();
+        if (duplicates.containsKey(key)) {
+          V value = duplicates.get(key);
+          if (value == null) {
+            continue; // delete this duplicate
+          }
+          entry = new ImmutableMapEntry<>(key, value);
+          duplicates.put(key, null);
+        }
+        newEntryArray[outI++] = entry;
+      }
+      entryArray = newEntryArray;
+    }
     return new JdkBackedImmutableMap<>(delegateMap, ImmutableList.asImmutableList(entryArray, n));
   }
 
@@ -61,13 +100,14 @@ public int size() {
   }
 
   @Override
-  public V get(@Nullable Object key) {
+  @CheckForNull
+  public V get(@CheckForNull Object key) {
     return delegateMap.get(key);
   }
 
   @Override
   ImmutableSet<Entry<K, V>> createEntrySet() {
-    return new ImmutableMapEntrySet.RegularEntrySet<K, V>(this, entries);
+    return new ImmutableMapEntrySet.RegularEntrySet<>(this, entries);
   }
 
   @Override
@@ -78,12 +118,12 @@ public void forEach(BiConsumer<? super K, ? super V> action) {
 
   @Override
   ImmutableSet<K> createKeySet() {
-    return new ImmutableMapKeySet<K, V>(this);
+    return new ImmutableMapKeySet<>(this);
   }
 
   @Override
   ImmutableCollection<V> createValues() {
-    return new ImmutableMapValues<K, V>(this);
+    return new ImmutableMapValues<>(this);
   }
 
   @Override
diff --git a/guava/src/com/google/common/collect/JdkBackedImmutableMultiset.java b/guava/src/com/google/common/collect/JdkBackedImmutableMultiset.java
index f2f196b6b3fa..faf22b343121 100644
--- a/guava/src/com/google/common/collect/JdkBackedImmutableMultiset.java
+++ b/guava/src/com/google/common/collect/JdkBackedImmutableMultiset.java
@@ -20,7 +20,7 @@
 import com.google.common.primitives.Ints;
 import java.util.Collection;
 import java.util.Map;
-import org.checkerframework.checker.nullness.qual.Nullable;
+import javax.annotation.CheckForNull;
 
 /**
  * An implementation of ImmutableMultiset backed by a JDK Map and a list of entries. Used to protect
@@ -29,6 +29,7 @@
  * @author Louis Wasserman
  */
 @GwtCompatible
+@ElementTypesAreNonnullByDefault
 final class JdkBackedImmutableMultiset<E> extends ImmutableMultiset<E> {
   private final Map<E, Integer> delegateMap;
   private final ImmutableList<Entry<E>> entries;
@@ -61,16 +62,16 @@ private JdkBackedImmutableMultiset(
   }
 
   @Override
-  public int count(@Nullable Object element) {
+  public int count(@CheckForNull Object element) {
     return delegateMap.getOrDefault(element, 0);
   }
 
-  private transient ImmutableSet<E> elementSet;
+  @CheckForNull private transient ImmutableSet<E> elementSet;
 
   @Override
   public ImmutableSet<E> elementSet() {
     ImmutableSet<E> result = elementSet;
-    return (result == null) ? elementSet = new ElementSet<E>(entries, this) : result;
+    return (result == null) ? elementSet = new ElementSet<>(entries, this) : result;
   }
 
   @Override
diff --git a/guava/src/com/google/common/collect/JdkBackedImmutableSet.java b/guava/src/com/google/common/collect/JdkBackedImmutableSet.java
index fa2c615e2ca8..c00167713cc9 100644
--- a/guava/src/com/google/common/collect/JdkBackedImmutableSet.java
+++ b/guava/src/com/google/common/collect/JdkBackedImmutableSet.java
@@ -16,7 +16,7 @@
 
 import com.google.common.annotations.GwtCompatible;
 import java.util.Set;
-import org.checkerframework.checker.nullness.qual.Nullable;
+import javax.annotation.CheckForNull;
 
 /**
  * ImmutableSet implementation backed by a JDK HashSet, used to defend against apparent hash
@@ -26,6 +26,7 @@
  * @author Louis Wasserman
  */
 @GwtCompatible(serializable = true)
+@ElementTypesAreNonnullByDefault
 final class JdkBackedImmutableSet<E> extends IndexedImmutableSet<E> {
   private final Set<?> delegate;
   private final ImmutableList<E> delegateList;
@@ -41,7 +42,7 @@ E get(int index) {
   }
 
   @Override
-  public boolean contains(@Nullable Object object) {
+  public boolean contains(@CheckForNull Object object) {
     return delegate.contains(object);
   }
 
diff --git a/guava/src/com/google/common/collect/LexicographicalOrdering.java b/guava/src/com/google/common/collect/LexicographicalOrdering.java
index 5e00eb439e4e..91fc7bf7241c 100644
--- a/guava/src/com/google/common/collect/LexicographicalOrdering.java
+++ b/guava/src/com/google/common/collect/LexicographicalOrdering.java
@@ -20,11 +20,14 @@
 import java.io.Serializable;
 import java.util.Comparator;
 import java.util.Iterator;
+import javax.annotation.CheckForNull;
 import org.checkerframework.checker.nullness.qual.Nullable;
 
 /** An ordering which sorts iterables by comparing corresponding elements pairwise. */
 @GwtCompatible(serializable = true)
-final class LexicographicalOrdering<T> extends Ordering<Iterable<T>> implements Serializable {
+@ElementTypesAreNonnullByDefault
+final class LexicographicalOrdering<T extends @Nullable Object> extends Ordering<Iterable<T>>
+    implements Serializable {
   final Comparator<? super T> elementOrder;
 
   LexicographicalOrdering(Comparator<? super T> elementOrder) {
@@ -51,7 +54,7 @@ public int compare(Iterable<T> leftIterable, Iterable<T> rightIterable) {
   }
 
   @Override
-  public boolean equals(@Nullable Object object) {
+  public boolean equals(@CheckForNull Object object) {
     if (object == this) {
       return true;
     }
diff --git a/guava/src/com/google/common/collect/LinkedHashMultimap.java b/guava/src/com/google/common/collect/LinkedHashMultimap.java
index 0f9e281fca57..62b358bcadcf 100644
--- a/guava/src/com/google/common/collect/LinkedHashMultimap.java
+++ b/guava/src/com/google/common/collect/LinkedHashMultimap.java
@@ -17,8 +17,9 @@
 package com.google.common.collect;
 
 import static com.google.common.base.Preconditions.checkNotNull;
+import static com.google.common.base.Preconditions.checkState;
 import static com.google.common.collect.CollectPreconditions.checkNonnegative;
-import static com.google.common.collect.CollectPreconditions.checkRemove;
+import static java.util.Objects.requireNonNull;
 
 import com.google.common.annotations.GwtCompatible;
 import com.google.common.annotations.GwtIncompatible;
@@ -40,6 +41,7 @@
 import java.util.Spliterator;
 import java.util.Spliterators;
 import java.util.function.Consumer;
+import javax.annotation.CheckForNull;
 import org.checkerframework.checker.nullness.qual.Nullable;
 import org.checkerframework.dataflow.qual.SideEffectFree;
 import org.checkerframework.framework.qual.AnnotatedFor;
@@ -71,9 +73,12 @@
  * read operations will work correctly. To allow concurrent update operations, wrap your multimap
  * with a call to {@link Multimaps#synchronizedSetMultimap}.
  *
+ * <p><b>Warning:</b> Do not modify either a key <i>or a value</i> of a {@code LinkedHashMultimap}
+ * in a way that affects its {@link Object#equals} behavior. Undefined behavior and bugs will
+ * result.
+ *
  * <p>See the Guava User Guide article on <a href=
- * "https://github.com/google/guava/wiki/NewCollectionTypesExplained#multimap"> {@code
- * Multimap}</a>.
+ * "https://github.com/google/guava/wiki/NewCollectionTypesExplained#multimap">{@code Multimap}</a>.
  *
  * @author Jared Levy
  * @author Louis Wasserman
@@ -81,11 +86,13 @@
  */
 @AnnotatedFor({"nullness"})
 @GwtCompatible(serializable = true, emulated = true)
-public final class LinkedHashMultimap<K, V>
+@ElementTypesAreNonnullByDefault
+public final class LinkedHashMultimap<K extends @Nullable Object, V extends @Nullable Object>
     extends LinkedHashMultimapGwtSerializationDependencies<K, V> {
 
   /** Creates a new, empty {@code LinkedHashMultimap} with the default initial capacities. */
-  public static <K, V> LinkedHashMultimap<K, V> create() {
+  public static <K extends @Nullable Object, V extends @Nullable Object>
+      LinkedHashMultimap<K, V> create() {
     return new LinkedHashMultimap<>(DEFAULT_KEY_CAPACITY, DEFAULT_VALUE_SET_CAPACITY);
   }
 
@@ -98,7 +105,8 @@ public static <K, V> LinkedHashMultimap<K, V> create() {
    * @throws IllegalArgumentException if {@code expectedKeys} or {@code expectedValuesPerKey} is
    *     negative
    */
-  public static <K, V> LinkedHashMultimap<K, V> create(int expectedKeys, int expectedValuesPerKey) {
+  public static <K extends @Nullable Object, V extends @Nullable Object>
+      LinkedHashMultimap<K, V> create(int expectedKeys, int expectedValuesPerKey) {
     return new LinkedHashMultimap<>(
         Maps.capacity(expectedKeys), Maps.capacity(expectedValuesPerKey));
   }
@@ -111,14 +119,14 @@ public static <K, V> LinkedHashMultimap<K, V> create(int expectedKeys, int expec
    *
    * @param multimap the multimap whose contents are copied to this multimap
    */
-  public static <K, V> LinkedHashMultimap<K, V> create(
-      Multimap<? extends K, ? extends V> multimap) {
+  public static <K extends @Nullable Object, V extends @Nullable Object>
+      LinkedHashMultimap<K, V> create(Multimap<? extends K, ? extends V> multimap) {
     LinkedHashMultimap<K, V> result = create(multimap.keySet().size(), DEFAULT_VALUE_SET_CAPACITY);
     result.putAll(multimap);
     return result;
   }
 
-  private interface ValueSetLink<K, V> {
+  private interface ValueSetLink<K extends @Nullable Object, V extends @Nullable Object> {
     ValueSetLink<K, V> getPredecessorInValueSet();
 
     ValueSetLink<K, V> getSuccessorInValueSet();
@@ -128,21 +136,25 @@ private interface ValueSetLink<K, V> {
     void setSuccessorInValueSet(ValueSetLink<K, V> entry);
   }
 
-  private static <K, V> void succeedsInValueSet(ValueSetLink<K, V> pred, ValueSetLink<K, V> succ) {
+  private static <K extends @Nullable Object, V extends @Nullable Object> void succeedsInValueSet(
+      ValueSetLink<K, V> pred, ValueSetLink<K, V> succ) {
     pred.setSuccessorInValueSet(succ);
     succ.setPredecessorInValueSet(pred);
   }
 
-  private static <K, V> void succeedsInMultimap(ValueEntry<K, V> pred, ValueEntry<K, V> succ) {
+  private static <K extends @Nullable Object, V extends @Nullable Object> void succeedsInMultimap(
+      ValueEntry<K, V> pred, ValueEntry<K, V> succ) {
     pred.setSuccessorInMultimap(succ);
     succ.setPredecessorInMultimap(pred);
   }
 
-  private static <K, V> void deleteFromValueSet(ValueSetLink<K, V> entry) {
+  private static <K extends @Nullable Object, V extends @Nullable Object> void deleteFromValueSet(
+      ValueSetLink<K, V> entry) {
     succeedsInValueSet(entry.getPredecessorInValueSet(), entry.getSuccessorInValueSet());
   }
 
-  private static <K, V> void deleteFromMultimap(ValueEntry<K, V> entry) {
+  private static <K extends @Nullable Object, V extends @Nullable Object> void deleteFromMultimap(
+      ValueEntry<K, V> entry) {
     succeedsInMultimap(entry.getPredecessorInMultimap(), entry.getSuccessorInMultimap());
   }
 
@@ -153,39 +165,69 @@ private static <K, V> void deleteFromMultimap(ValueEntry<K, V> entry) {
    * whole.
    */
   @VisibleForTesting
-  static final class ValueEntry<K, V> extends ImmutableEntry<K, V> implements ValueSetLink<K, V> {
+  static final class ValueEntry<K extends @Nullable Object, V extends @Nullable Object>
+      extends ImmutableEntry<K, V> implements ValueSetLink<K, V> {
     final int smearedValueHash;
 
-    @Nullable ValueEntry<K, V> nextInValueBucket;
+    @CheckForNull ValueEntry<K, V> nextInValueBucket;
+    /*
+     * The *InValueSet and *InMultimap fields below are null after construction, but we almost
+     * always call succeedsIn*() to initialize them immediately thereafter.
+     *
+     * The exception is the *InValueSet fields of multimapHeaderEntry, which are never set. (That
+     * works out fine as long as we continue to be careful not to try delete them or iterate past
+     * them.)
+     *
+     * We could consider "lying" and omitting @CheckNotNull from all these fields. Normally, I'm not
+     * a fan of that: What if we someday implement (presumably to be enabled during tests only)
+     * bytecode rewriting that checks for any null value that passes through an API with a
+     * known-non-null type? But that particular problem might not arise here, since we're not
+     * actually reading from the fields in any case in which they might be null (as proven by the
+     * requireNonNull checks below). Plus, we're *already* lying here, since newHeader passes a null
+     * key and value, which we pass to the superconstructor, even though the key and value type for
+     * a given entry might not include null. The right fix for the header problems is probably to
+     * define a separate MultimapLink interface with a separate "header" implementation, which
+     * hopefully could avoid implementing Entry or ValueSetLink at all. (But note that that approach
+     * requires us to define extra classes -- unfortunate under Android.) *Then* we could consider
+     * lying about the fields below on the grounds that we always initialize them just after the
+     * constructor -- an example of the kind of lying that our hypotheticaly bytecode rewriter would
+     * already have to deal with, thanks to DI frameworks that perform field and method injection,
+     * frameworks like Android that define post-construct hooks like Activity.onCreate, etc.
+     */
 
-    @Nullable ValueSetLink<K, V> predecessorInValueSet;
-    @Nullable ValueSetLink<K, V> successorInValueSet;
+    @CheckForNull ValueSetLink<K, V> predecessorInValueSet;
+    @CheckForNull ValueSetLink<K, V> successorInValueSet;
 
-    @Nullable ValueEntry<K, V> predecessorInMultimap;
-    @Nullable ValueEntry<K, V> successorInMultimap;
+    @CheckForNull ValueEntry<K, V> predecessorInMultimap;
+    @CheckForNull ValueEntry<K, V> successorInMultimap;
 
     ValueEntry(
-        @Nullable K key,
-        @Nullable V value,
+        @ParametricNullness K key,
+        @ParametricNullness V value,
         int smearedValueHash,
-        @Nullable ValueEntry<K, V> nextInValueBucket) {
+        @CheckForNull ValueEntry<K, V> nextInValueBucket) {
       super(key, value);
       this.smearedValueHash = smearedValueHash;
       this.nextInValueBucket = nextInValueBucket;
     }
 
-    boolean matchesValue(@Nullable Object v, int smearedVHash) {
+    @SuppressWarnings("nullness") // see the comment on the class fields, especially about newHeader
+    static <K extends @Nullable Object, V extends @Nullable Object> ValueEntry<K, V> newHeader() {
+      return new ValueEntry<>(null, null, 0, null);
+    }
+
+    boolean matchesValue(@CheckForNull Object v, int smearedVHash) {
       return smearedValueHash == smearedVHash && Objects.equal(getValue(), v);
     }
 
     @Override
     public ValueSetLink<K, V> getPredecessorInValueSet() {
-      return predecessorInValueSet;
+      return requireNonNull(predecessorInValueSet); // see the comment on the class fields
     }
 
     @Override
     public ValueSetLink<K, V> getSuccessorInValueSet() {
-      return successorInValueSet;
+      return requireNonNull(successorInValueSet); // see the comment on the class fields
     }
 
     @Override
@@ -199,11 +241,11 @@ public void setSuccessorInValueSet(ValueSetLink<K, V> entry) {
     }
 
     public ValueEntry<K, V> getPredecessorInMultimap() {
-      return predecessorInMultimap;
+      return requireNonNull(predecessorInMultimap); // see the comment on the class fields
     }
 
     public ValueEntry<K, V> getSuccessorInMultimap() {
-      return successorInMultimap;
+      return requireNonNull(successorInMultimap); // see the comment on the class fields
     }
 
     public void setSuccessorInMultimap(ValueEntry<K, V> multimapSuccessor) {
@@ -227,7 +269,7 @@ private LinkedHashMultimap(int keyCapacity, int valueSetCapacity) {
     checkNonnegative(valueSetCapacity, "expectedValuesPerKey");
 
     this.valueSetCapacity = valueSetCapacity;
-    this.multimapHeaderEntry = new ValueEntry<>(null, null, 0, null);
+    this.multimapHeaderEntry = ValueEntry.newHeader();
     succeedsInMultimap(multimapHeaderEntry, multimapHeaderEntry);
   }
 
@@ -253,7 +295,7 @@ Set<V> createCollection() {
    * @return a new decorated set containing a collection of values for one key
    */
   @Override
-  Collection<V> createCollection(K key) {
+  Collection<V> createCollection(@ParametricNullness K key) {
     return new ValueSet(key, valueSetCapacity);
   }
 
@@ -266,7 +308,7 @@ Collection<V> createCollection(K key) {
    */
   @CanIgnoreReturnValue
   @Override
-  public Set<V> replaceValues(@Nullable K key, Iterable<? extends V> values) {
+  public Set<V> replaceValues(@ParametricNullness K key, Iterable<? extends V> values) {
     return super.replaceValues(key, values);
   }
 
@@ -323,8 +365,8 @@ final class ValueSet extends Sets.ImprovedAbstractSet<V> implements ValueSetLink
      * consumption.
      */
 
-    private final K key;
-    @VisibleForTesting ValueEntry<K, V>[] hashTable;
+    @ParametricNullness private final K key;
+    @VisibleForTesting @Nullable ValueEntry<K, V>[] hashTable;
     private int size = 0;
     private int modCount = 0;
 
@@ -333,15 +375,16 @@ final class ValueSet extends Sets.ImprovedAbstractSet<V> implements ValueSetLink
     private ValueSetLink<K, V> firstEntry;
     private ValueSetLink<K, V> lastEntry;
 
-    ValueSet(K key, int expectedValues) {
+    ValueSet(@ParametricNullness K key, int expectedValues) {
       this.key = key;
       this.firstEntry = this;
       this.lastEntry = this;
       // Round expected values up to a power of 2 to get the table size.
       int tableSize = Hashing.closedTableSize(expectedValues, VALUE_SET_LOAD_FACTOR);
 
-      @SuppressWarnings("unchecked")
-      ValueEntry<K, V>[] hashTable = new ValueEntry[tableSize];
+      @SuppressWarnings({"rawtypes", "unchecked"})
+      @Nullable
+      ValueEntry<K, V>[] hashTable = new @Nullable ValueEntry[tableSize];
       this.hashTable = hashTable;
     }
 
@@ -373,7 +416,7 @@ public void setSuccessorInValueSet(ValueSetLink<K, V> entry) {
     public Iterator<V> iterator() {
       return new Iterator<V>() {
         ValueSetLink<K, V> nextEntry = firstEntry;
-        @Nullable ValueEntry<K, V> toRemove;
+        @CheckForNull ValueEntry<K, V> toRemove;
         int expectedModCount = modCount;
 
         private void checkForComodification() {
@@ -389,6 +432,7 @@ public boolean hasNext() {
         }
 
         @Override
+        @ParametricNullness
         public V next() {
           if (!hasNext()) {
             throw new NoSuchElementException();
@@ -403,7 +447,7 @@ public V next() {
         @Override
         public void remove() {
           checkForComodification();
-          checkRemove(toRemove != null);
+          checkState(toRemove != null, "no calls to next() since the last call to remove()");
           ValueSet.this.remove(toRemove.getValue());
           expectedModCount = modCount;
           toRemove = null;
@@ -427,7 +471,7 @@ public int size() {
     }
 
     @Override
-    public boolean contains(@Nullable Object o) {
+    public boolean contains(@CheckForNull Object o) {
       int smearedHash = Hashing.smearedHash(o);
       for (ValueEntry<K, V> entry = hashTable[smearedHash & mask()];
           entry != null;
@@ -440,7 +484,7 @@ public boolean contains(@Nullable Object o) {
     }
 
     @Override
-    public boolean add(@Nullable V value) {
+    public boolean add(@ParametricNullness V value) {
       int smearedHash = Hashing.smearedHash(value);
       int bucket = smearedHash & mask();
       ValueEntry<K, V> rowHead = hashTable[bucket];
@@ -481,7 +525,7 @@ private void rehashIfNecessary() {
 
     @CanIgnoreReturnValue
     @Override
-    public boolean remove(@Nullable Object o) {
+    public boolean remove(@CheckForNull Object o) {
       int smearedHash = Hashing.smearedHash(o);
       int bucket = smearedHash & mask();
       ValueEntry<K, V> prev = null;
@@ -523,8 +567,8 @@ public void clear() {
   @Override
   Iterator<Entry<K, V>> entryIterator() {
     return new Iterator<Entry<K, V>>() {
-      ValueEntry<K, V> nextEntry = multimapHeaderEntry.successorInMultimap;
-      @Nullable ValueEntry<K, V> toRemove;
+      ValueEntry<K, V> nextEntry = multimapHeaderEntry.getSuccessorInMultimap();
+      @CheckForNull ValueEntry<K, V> toRemove;
 
       @Override
       public boolean hasNext() {
@@ -538,13 +582,13 @@ public Entry<K, V> next() {
         }
         ValueEntry<K, V> result = nextEntry;
         toRemove = result;
-        nextEntry = nextEntry.successorInMultimap;
+        nextEntry = nextEntry.getSuccessorInMultimap();
         return result;
       }
 
       @Override
       public void remove() {
-        checkRemove(toRemove != null);
+        checkState(toRemove != null, "no calls to next() since the last call to remove()");
         LinkedHashMultimap.this.remove(toRemove.getKey(), toRemove.getValue());
         toRemove = null;
       }
@@ -593,7 +637,7 @@ private void writeObject(ObjectOutputStream stream) throws IOException {
   @GwtIncompatible // java.io.ObjectInputStream
   private void readObject(ObjectInputStream stream) throws IOException, ClassNotFoundException {
     stream.defaultReadObject();
-    multimapHeaderEntry = new ValueEntry<>(null, null, 0, null);
+    multimapHeaderEntry = ValueEntry.newHeader();
     succeedsInMultimap(multimapHeaderEntry, multimapHeaderEntry);
     valueSetCapacity = DEFAULT_VALUE_SET_CAPACITY;
     int distinctKeys = stream.readInt();
@@ -609,7 +653,11 @@ private void readObject(ObjectInputStream stream) throws IOException, ClassNotFo
       K key = (K) stream.readObject();
       @SuppressWarnings("unchecked")
       V value = (V) stream.readObject();
-      map.get(key).add(value);
+      /*
+       * requireNonNull is safe for a properly serialized multimap: We've already inserted a
+       * collection for each key that we expect.
+       */
+      requireNonNull(map.get(key)).add(value);
     }
     setMap(map);
   }
diff --git a/guava/src/com/google/common/collect/LinkedHashMultiset.java b/guava/src/com/google/common/collect/LinkedHashMultiset.java
index 1b338ab20b76..2122918b53e2 100644
--- a/guava/src/com/google/common/collect/LinkedHashMultiset.java
+++ b/guava/src/com/google/common/collect/LinkedHashMultiset.java
@@ -35,8 +35,7 @@
  * element will appear at the end of the iteration.
  *
  * <p>See the Guava User Guide article on <a href=
- * "https://github.com/google/guava/wiki/NewCollectionTypesExplained#multiset"> {@code
- * Multiset}</a>.
+ * "https://github.com/google/guava/wiki/NewCollectionTypesExplained#multiset">{@code Multiset}</a>.
  *
  * @author Kevin Bourrillion
  * @author Jared Levy
@@ -44,10 +43,12 @@
  */
 @AnnotatedFor({"nullness"})
 @GwtCompatible(serializable = true, emulated = true)
-public final class LinkedHashMultiset<E> extends AbstractMapBasedMultiset<E> {
+@ElementTypesAreNonnullByDefault
+public final class LinkedHashMultiset<E extends @Nullable Object>
+    extends AbstractMapBasedMultiset<E> {
 
   /** Creates a new, empty {@code LinkedHashMultiset} using the default initial capacity. */
-  public static <E> LinkedHashMultiset<E> create() {
+  public static <E extends @Nullable Object> LinkedHashMultiset<E> create() {
     return new LinkedHashMultiset<E>();
   }
 
@@ -58,7 +59,7 @@ public static <E> LinkedHashMultiset<E> create() {
    * @param distinctElements the expected number of distinct elements
    * @throws IllegalArgumentException if {@code distinctElements} is negative
    */
-  public static <E> LinkedHashMultiset<E> create(int distinctElements) {
+  public static <E extends @Nullable Object> LinkedHashMultiset<E> create(int distinctElements) {
     return new LinkedHashMultiset<E>(distinctElements);
   }
 
@@ -69,7 +70,8 @@ public static <E> LinkedHashMultiset<E> create(int distinctElements) {
    *
    * @param elements the elements that the multiset should contain
    */
-  public static <E> LinkedHashMultiset<E> create(Iterable<? extends E> elements) {
+  public static <E extends @Nullable Object> LinkedHashMultiset<E> create(
+      Iterable<? extends E> elements) {
     LinkedHashMultiset<E> multiset = create(Multisets.inferDistinctElements(elements));
     Iterables.addAll(multiset, elements);
     return multiset;
diff --git a/guava/src/com/google/common/collect/LinkedListMultimap.java b/guava/src/com/google/common/collect/LinkedListMultimap.java
index 46ac329568cb..14daed163c6b 100644
--- a/guava/src/com/google/common/collect/LinkedListMultimap.java
+++ b/guava/src/com/google/common/collect/LinkedListMultimap.java
@@ -19,8 +19,8 @@
 import static com.google.common.base.Preconditions.checkNotNull;
 import static com.google.common.base.Preconditions.checkPositionIndex;
 import static com.google.common.base.Preconditions.checkState;
-import static com.google.common.collect.CollectPreconditions.checkRemove;
 import static java.util.Collections.unmodifiableList;
+import static java.util.Objects.requireNonNull;
 
 import com.google.common.annotations.GwtCompatible;
 import com.google.common.annotations.GwtIncompatible;
@@ -41,6 +41,7 @@
 import java.util.NoSuchElementException;
 import java.util.Set;
 import java.util.function.Consumer;
+import javax.annotation.CheckForNull;
 import org.checkerframework.checker.nullness.qual.Nullable;
 import org.checkerframework.dataflow.qual.Pure;
 import org.checkerframework.dataflow.qual.SideEffectFree;
@@ -92,16 +93,16 @@
  * with a call to {@link Multimaps#synchronizedListMultimap}.
  *
  * <p>See the Guava User Guide article on <a href=
- * "https://github.com/google/guava/wiki/NewCollectionTypesExplained#multimap"> {@code
- * Multimap}</a>.
+ * "https://github.com/google/guava/wiki/NewCollectionTypesExplained#multimap">{@code Multimap}</a>.
  *
  * @author Mike Bostock
  * @since 2.0
  */
 @AnnotatedFor({"nullness"})
 @GwtCompatible(serializable = true, emulated = true)
-public class LinkedListMultimap<K, V> extends AbstractMultimap<K, V>
-    implements ListMultimap<K, V>, Serializable {
+@ElementTypesAreNonnullByDefault
+public class LinkedListMultimap<K extends @Nullable Object, V extends @Nullable Object>
+    extends AbstractMultimap<K, V> implements ListMultimap<K, V>, Serializable {
   /*
    * Order is maintained using a linked list containing all key-value pairs. In
    * addition, a series of disjoint linked lists of "siblings", each containing
@@ -109,38 +110,42 @@ public class LinkedListMultimap<K, V> extends AbstractMultimap<K, V>
    * ValueForKeyIterator} in constant time.
    */
 
-  private static final class Node<K, V> extends AbstractMapEntry<K, V> {
-    final @Nullable K key;
-    @Nullable V value;
-    @Nullable Node<K, V> next; // the next node (with any key)
-    @Nullable Node<K, V> previous; // the previous node (with any key)
-    @Nullable Node<K, V> nextSibling; // the next node with the same key
-    @Nullable Node<K, V> previousSibling; // the previous node with the same key
+  private static final class Node<K extends @Nullable Object, V extends @Nullable Object>
+      extends AbstractMapEntry<K, V> {
+    @ParametricNullness final K key;
+    @ParametricNullness V value;
+    @CheckForNull Node<K, V> next; // the next node (with any key)
+    @CheckForNull Node<K, V> previous; // the previous node (with any key)
+    @CheckForNull Node<K, V> nextSibling; // the next node with the same key
+    @CheckForNull Node<K, V> previousSibling; // the previous node with the same key
 
-    Node(@Nullable K key, @Nullable V value) {
+    Node(@ParametricNullness K key, @ParametricNullness V value) {
       this.key = key;
       this.value = value;
     }
 
     @Override
+    @ParametricNullness
     public K getKey() {
       return key;
     }
 
     @Override
+    @ParametricNullness
     public V getValue() {
       return value;
     }
 
     @Override
-    public V setValue(@Nullable V newValue) {
+    @ParametricNullness
+    public V setValue(@ParametricNullness V newValue) {
       V result = value;
       this.value = newValue;
       return result;
     }
   }
 
-  private static class KeyList<K, V> {
+  private static class KeyList<K extends @Nullable Object, V extends @Nullable Object> {
     Node<K, V> head;
     Node<K, V> tail;
     int count;
@@ -154,8 +159,8 @@ private static class KeyList<K, V> {
     }
   }
 
-  private transient @Nullable Node<K, V> head; // the head for all keys
-  private transient @Nullable Node<K, V> tail; // the tail for all keys
+  @CheckForNull private transient Node<K, V> head; // the head for all keys
+  @CheckForNull private transient Node<K, V> tail; // the tail for all keys
   private transient Map<K, KeyList<K, V>> keyToKeyList;
   private transient int size;
 
@@ -167,7 +172,8 @@ private static class KeyList<K, V> {
   private transient int modCount;
 
   /** Creates a new, empty {@code LinkedListMultimap} with the default initial capacity. */
-  public static <K, V> LinkedListMultimap<K, V> create() {
+  public static <K extends @Nullable Object, V extends @Nullable Object>
+      LinkedListMultimap<K, V> create() {
     return new LinkedListMultimap<>();
   }
 
@@ -178,7 +184,8 @@ public static <K, V> LinkedListMultimap<K, V> create() {
    * @param expectedKeys the expected number of distinct keys
    * @throws IllegalArgumentException if {@code expectedKeys} is negative
    */
-  public static <K, V> LinkedListMultimap<K, V> create(int expectedKeys) {
+  public static <K extends @Nullable Object, V extends @Nullable Object>
+      LinkedListMultimap<K, V> create(int expectedKeys) {
     return new LinkedListMultimap<>(expectedKeys);
   }
 
@@ -189,8 +196,8 @@ public static <K, V> LinkedListMultimap<K, V> create(int expectedKeys) {
    *
    * @param multimap the multimap whose contents are copied to this multimap
    */
-  public static <K, V> LinkedListMultimap<K, V> create(
-      Multimap<? extends K, ? extends V> multimap) {
+  public static <K extends @Nullable Object, V extends @Nullable Object>
+      LinkedListMultimap<K, V> create(Multimap<? extends K, ? extends V> multimap) {
     return new LinkedListMultimap<>(multimap);
   }
 
@@ -213,14 +220,18 @@ private LinkedListMultimap(Multimap<? extends K, ? extends V> multimap) {
    * is specified, it MUST be for an node for the same {@code key}!
    */
   @CanIgnoreReturnValue
-  private Node<K, V> addNode(@Nullable K key, @Nullable V value, @Nullable Node<K, V> nextSibling) {
+  private Node<K, V> addNode(
+      @ParametricNullness K key,
+      @ParametricNullness V value,
+      @CheckForNull Node<K, V> nextSibling) {
     Node<K, V> node = new Node<>(key, value);
     if (head == null) { // empty list
       head = tail = node;
       keyToKeyList.put(key, new KeyList<K, V>(node));
       modCount++;
     } else if (nextSibling == null) { // non-empty list, add to tail
-      tail.next = node;
+      // requireNonNull is safe because the list is non-empty.
+      requireNonNull(tail).next = node;
       node.previous = tail;
       tail = node;
       KeyList<K, V> keyList = keyToKeyList.get(key);
@@ -235,14 +246,19 @@ private Node<K, V> addNode(@Nullable K key, @Nullable V value, @Nullable Node<K,
         keyList.tail = node;
       }
     } else { // non-empty list, insert before nextSibling
-      KeyList<K, V> keyList = keyToKeyList.get(key);
+      /*
+       * requireNonNull is safe as long as callers pass a nextSibling that (a) has the same key and
+       * (b) is present in the multimap. (And they do, except maybe in case of concurrent
+       * modification, in which case all bets are off.)
+       */
+      KeyList<K, V> keyList = requireNonNull(keyToKeyList.get(key));
       keyList.count++;
       node.previous = nextSibling.previous;
       node.previousSibling = nextSibling.previousSibling;
       node.next = nextSibling;
       node.nextSibling = nextSibling;
       if (nextSibling.previousSibling == null) { // nextSibling was key head
-        keyToKeyList.get(key).head = node;
+        keyList.head = node;
       } else {
         nextSibling.previousSibling.nextSibling = node;
       }
@@ -274,21 +290,29 @@ private void removeNode(Node<K, V> node) {
       tail = node.previous;
     }
     if (node.previousSibling == null && node.nextSibling == null) {
-      KeyList<K, V> keyList = keyToKeyList.remove(node.key);
+      /*
+       * requireNonNull is safe as long as we call removeNode only for nodes that are still in the
+       * Multimap. This should be the case (except in case of concurrent modification, when all bets
+       * are off).
+       */
+      KeyList<K, V> keyList = requireNonNull(keyToKeyList.remove(node.key));
       keyList.count = 0;
       modCount++;
     } else {
-      KeyList<K, V> keyList = keyToKeyList.get(node.key);
+      // requireNonNull is safe (under the conditions listed in the comment in the branch above).
+      KeyList<K, V> keyList = requireNonNull(keyToKeyList.get(node.key));
       keyList.count--;
 
       if (node.previousSibling == null) {
-        keyList.head = node.nextSibling;
+        // requireNonNull is safe because we checked that not *both* siblings were null.
+        keyList.head = requireNonNull(node.nextSibling);
       } else {
         node.previousSibling.nextSibling = node.nextSibling;
       }
 
       if (node.nextSibling == null) {
-        keyList.tail = node.previousSibling;
+        // requireNonNull is safe because we checked that not *both* siblings were null.
+        keyList.tail = requireNonNull(node.previousSibling);
       } else {
         node.nextSibling.previousSibling = node.previousSibling;
       }
@@ -297,23 +321,16 @@ private void removeNode(Node<K, V> node) {
   }
 
   /** Removes all nodes for the specified key. */
-  private void removeAllNodes(@Nullable Object key) {
+  private void removeAllNodes(@ParametricNullness K key) {
     Iterators.clear(new ValueForKeyIterator(key));
   }
 
-  /** Helper method for verifying that an iterator element is present. */
-  private static void checkElement(@Nullable Object node) {
-    if (node == null) {
-      throw new NoSuchElementException();
-    }
-  }
-
   /** An {@code Iterator} over all nodes. */
   private class NodeIterator implements ListIterator<Entry<K, V>> {
     int nextIndex;
-    @Nullable Node<K, V> next;
-    @Nullable Node<K, V> current;
-    @Nullable Node<K, V> previous;
+    @CheckForNull Node<K, V> next;
+    @CheckForNull Node<K, V> current;
+    @CheckForNull Node<K, V> previous;
     int expectedModCount = modCount;
 
     NodeIterator(int index) {
@@ -350,7 +367,9 @@ public boolean hasNext() {
     @Override
     public Node<K, V> next() {
       checkForConcurrentModification();
-      checkElement(next);
+      if (next == null) {
+        throw new NoSuchElementException();
+      }
       previous = current = next;
       next = next.next;
       nextIndex++;
@@ -360,7 +379,7 @@ public Node<K, V> next() {
     @Override
     public void remove() {
       checkForConcurrentModification();
-      checkRemove(current != null);
+      checkState(current != null, "no calls to next() since the last call to remove()");
       if (current != next) { // after call to next()
         previous = current.previous;
         nextIndex--;
@@ -382,7 +401,9 @@ public boolean hasPrevious() {
     @Override
     public Node<K, V> previous() {
       checkForConcurrentModification();
-      checkElement(previous);
+      if (previous == null) {
+        throw new NoSuchElementException();
+      }
       next = current = previous;
       previous = previous.previous;
       nextIndex--;
@@ -409,7 +430,7 @@ public void add(Entry<K, V> e) {
       throw new UnsupportedOperationException();
     }
 
-    void setValue(V value) {
+    void setValue(@ParametricNullness V value) {
       checkState(current != null);
       current.value = value;
     }
@@ -418,8 +439,8 @@ void setValue(V value) {
   /** An {@code Iterator} over distinct keys in key head order. */
   private class DistinctKeyIterator implements Iterator<K> {
     final Set<K> seenKeys = Sets.<K>newHashSetWithExpectedSize(keySet().size());
-    @Nullable Node<K, V> next = head;
-    @Nullable Node<K, V> current;
+    @CheckForNull Node<K, V> next = head;
+    @CheckForNull Node<K, V> current;
     int expectedModCount = modCount;
 
     private void checkForConcurrentModification() {
@@ -435,9 +456,12 @@ public boolean hasNext() {
     }
 
     @Override
+    @ParametricNullness
     public K next() {
       checkForConcurrentModification();
-      checkElement(next);
+      if (next == null) {
+        throw new NoSuchElementException();
+      }
       current = next;
       seenKeys.add(current.key);
       do { // skip ahead to next unseen key
@@ -449,7 +473,7 @@ public K next() {
     @Override
     public void remove() {
       checkForConcurrentModification();
-      checkRemove(current != null);
+      checkState(current != null, "no calls to next() since the last call to remove()");
       removeAllNodes(current.key);
       current = null;
       expectedModCount = modCount;
@@ -458,14 +482,14 @@ public void remove() {
 
   /** A {@code ListIterator} over values for a specified key. */
   private class ValueForKeyIterator implements ListIterator<V> {
-    final @Nullable Object key;
+    @ParametricNullness final K key;
     int nextIndex;
-    @Nullable Node<K, V> next;
-    @Nullable Node<K, V> current;
-    @Nullable Node<K, V> previous;
+    @CheckForNull Node<K, V> next;
+    @CheckForNull Node<K, V> current;
+    @CheckForNull Node<K, V> previous;
 
     /** Constructs a new iterator over all values for the specified key. */
-    ValueForKeyIterator(@Nullable Object key) {
+    ValueForKeyIterator(@ParametricNullness K key) {
       this.key = key;
       KeyList<K, V> keyList = keyToKeyList.get(key);
       next = (keyList == null) ? null : keyList.head;
@@ -479,7 +503,7 @@ private class ValueForKeyIterator implements ListIterator<V> {
      *
      * @throws IndexOutOfBoundsException if index is invalid
      */
-    public ValueForKeyIterator(@Nullable Object key, int index) {
+    public ValueForKeyIterator(@ParametricNullness K key, int index) {
       KeyList<K, V> keyList = keyToKeyList.get(key);
       int size = (keyList == null) ? 0 : keyList.count;
       checkPositionIndex(index, size);
@@ -506,8 +530,11 @@ public boolean hasNext() {
 
     @CanIgnoreReturnValue
     @Override
+    @ParametricNullness
     public V next() {
-      checkElement(next);
+      if (next == null) {
+        throw new NoSuchElementException();
+      }
       previous = current = next;
       next = next.nextSibling;
       nextIndex++;
@@ -521,8 +548,11 @@ public boolean hasPrevious() {
 
     @CanIgnoreReturnValue
     @Override
+    @ParametricNullness
     public V previous() {
-      checkElement(previous);
+      if (previous == null) {
+        throw new NoSuchElementException();
+      }
       next = current = previous;
       previous = previous.previousSibling;
       nextIndex--;
@@ -541,7 +571,7 @@ public int previousIndex() {
 
     @Override
     public void remove() {
-      checkRemove(current != null);
+      checkState(current != null, "no calls to next() since the last call to remove()");
       if (current != next) { // after call to next()
         previous = current.previousSibling;
         nextIndex--;
@@ -553,15 +583,14 @@ public void remove() {
     }
 
     @Override
-    public void set(V value) {
+    public void set(@ParametricNullness V value) {
       checkState(current != null);
       current.value = value;
     }
 
     @Override
-    @SuppressWarnings("unchecked")
-    public void add(V value) {
-      previous = addNode((K) key, value, next);
+    public void add(@ParametricNullness V value) {
+      previous = addNode(key, value, next);
       nextIndex++;
       current = null;
     }
@@ -583,13 +612,13 @@ public boolean isEmpty() {
 
   @Pure
   @Override
-  public boolean containsKey(@Nullable Object key) {
+  public boolean containsKey(@CheckForNull Object key) {
     return keyToKeyList.containsKey(key);
   }
 
   @Pure
   @Override
-  public boolean containsValue(@Nullable Object value) {
+  public boolean containsValue(@CheckForNull Object value) {
     return values().contains(value);
   }
 
@@ -604,7 +633,7 @@ public boolean containsValue(@Nullable Object value) {
    */
   @CanIgnoreReturnValue
   @Override
-  public boolean put(@Nullable K key, @Nullable V value) {
+  public boolean put(@ParametricNullness K key, @ParametricNullness V value) {
     addNode(key, value, null);
     return true;
   }
@@ -621,7 +650,7 @@ public boolean put(@Nullable K key, @Nullable V value) {
    */
   @CanIgnoreReturnValue
   @Override
-  public List<V> replaceValues(@Nullable K key, Iterable<? extends V> values) {
+  public List<V> replaceValues(@ParametricNullness K key, Iterable<? extends V> values) {
     List<V> oldValues = getCopy(key);
     ListIterator<V> keyValues = new ValueForKeyIterator(key);
     Iterator<? extends V> newValues = values.iterator();
@@ -646,7 +675,7 @@ public List<V> replaceValues(@Nullable K key, Iterable<? extends V> values) {
     return oldValues;
   }
 
-  private List<V> getCopy(@Nullable Object key) {
+  private List<V> getCopy(@ParametricNullness K key) {
     return unmodifiableList(Lists.newArrayList(new ValueForKeyIterator(key)));
   }
 
@@ -658,8 +687,15 @@ private List<V> getCopy(@Nullable Object key) {
   @CanIgnoreReturnValue
   @Override
   public List<V> removeAll(@Nullable Object key) {
-    List<V> oldValues = getCopy(key);
-    removeAllNodes(key);
+    /*
+     * Safe because all we do is remove values for the key, not add them. (If we wanted to make sure
+     * to call getCopy and removeAllNodes only with a true K, then we could check containsKey first.
+     * But that check wouldn't eliminate the warnings.)
+     */
+    @SuppressWarnings({"unchecked", "nullness"})
+    K castKey = (K) key;
+    List<V> oldValues = getCopy(castKey);
+    removeAllNodes(castKey);
     return oldValues;
   }
 
@@ -684,7 +720,7 @@ public void clear() {
    * <p>The returned list is not serializable and does not have random access.
    */
   @Override
-  public List<V> get(final @Nullable K key) {
+  public List<V> get(@ParametricNullness final K key) {
     return new AbstractSequentialList<V>() {
       @Pure
       @Override
@@ -716,12 +752,12 @@ public Iterator<K> iterator() {
 
       @Pure
       @Override
-      public boolean contains(@Nullable Object key) { // for performance
+      public boolean contains(@CheckForNull Object key) { // for performance
         return containsKey(key);
       }
 
       @Override
-      public boolean remove(Object o) { // for performance
+      public boolean remove(@CheckForNull Object o) { // for performance
         return !LinkedListMultimap.this.removeAll(o).isEmpty();
       }
     }
@@ -761,12 +797,13 @@ public ListIterator<V> listIterator(int index) {
         final NodeIterator nodeItr = new NodeIterator(index);
         return new TransformedListIterator<Entry<K, V>, V>(nodeItr) {
           @Override
+          @ParametricNullness
           V transform(Entry<K, V> entry) {
             return entry.getValue();
           }
 
           @Override
-          public void set(V value) {
+          public void set(@ParametricNullness V value) {
             nodeItr.setValue(value);
           }
         };
diff --git a/guava/src/com/google/common/collect/ListMultimap.java b/guava/src/com/google/common/collect/ListMultimap.java
index 9eb31f97ac9c..1dd9917d9229 100644
--- a/guava/src/com/google/common/collect/ListMultimap.java
+++ b/guava/src/com/google/common/collect/ListMultimap.java
@@ -21,6 +21,7 @@
 import java.util.Collection;
 import java.util.List;
 import java.util.Map;
+import javax.annotation.CheckForNull;
 import org.checkerframework.checker.nullness.qual.Nullable;
 import org.checkerframework.dataflow.qual.Pure;
 import org.checkerframework.framework.qual.AnnotatedFor;
@@ -35,15 +36,16 @@
  * {@link #asMap} has {@code List} values.
  *
  * <p>See the Guava User Guide article on <a href=
- * "https://github.com/google/guava/wiki/NewCollectionTypesExplained#multimap"> {@code
- * Multimap}</a>.
+ * "https://github.com/google/guava/wiki/NewCollectionTypesExplained#multimap">{@code Multimap}</a>.
  *
  * @author Jared Levy
  * @since 2.0
  */
 @GwtCompatible
 @AnnotatedFor({"nullness"})
-public interface ListMultimap<K, V> extends Multimap<K, V> {
+@ElementTypesAreNonnullByDefault
+public interface ListMultimap<K extends @Nullable Object, V extends @Nullable Object>
+    extends Multimap<K, V> {
   /**
    * {@inheritDoc}
    *
@@ -52,7 +54,7 @@ public interface ListMultimap<K, V> extends Multimap<K, V> {
    * the {@link Multimap} interface.
    */
   @Override
-  List<V> get(@Nullable K key);
+  List<V> get(@ParametricNullness K key);
 
   /**
    * {@inheritDoc}
@@ -63,7 +65,7 @@ public interface ListMultimap<K, V> extends Multimap<K, V> {
    */
   @CanIgnoreReturnValue
   @Override
-  List<V> removeAll(@Nullable Object key);
+  List<V> removeAll(@CheckForNull Object key);
 
   /**
    * {@inheritDoc}
@@ -74,7 +76,7 @@ public interface ListMultimap<K, V> extends Multimap<K, V> {
    */
   @CanIgnoreReturnValue
   @Override
-  List<V> replaceValues(K key, Iterable<? extends V> values);
+  List<V> replaceValues(@ParametricNullness K key, Iterable<? extends V> values);
 
   /**
    * {@inheritDoc}
@@ -97,5 +99,5 @@ public interface ListMultimap<K, V> extends Multimap<K, V> {
    */
   @Pure
   @Override
-  boolean equals(@Nullable Object obj);
+  boolean equals(@CheckForNull Object obj);
 }
diff --git a/guava/src/com/google/common/collect/Lists.java b/guava/src/com/google/common/collect/Lists.java
index 2fa707e03fe3..79a2100b0258 100644
--- a/guava/src/com/google/common/collect/Lists.java
+++ b/guava/src/com/google/common/collect/Lists.java
@@ -49,6 +49,7 @@
 import java.util.RandomAccess;
 import java.util.concurrent.CopyOnWriteArrayList;
 import java.util.function.Predicate;
+import javax.annotation.CheckForNull;
 import org.checkerframework.checker.nullness.qual.Nullable;
 import org.checkerframework.dataflow.qual.Pure;
 import org.checkerframework.framework.qual.AnnotatedFor;
@@ -58,7 +59,7 @@
  * {@link Sets}, {@link Maps} and {@link Queues}.
  *
  * <p>See the Guava User Guide article on <a href=
- * "https://github.com/google/guava/wiki/CollectionUtilitiesExplained#lists"> {@code Lists}</a>.
+ * "https://github.com/google/guava/wiki/CollectionUtilitiesExplained#lists">{@code Lists}</a>.
  *
  * @author Kevin Bourrillion
  * @author Mike Bostock
@@ -67,6 +68,7 @@
  */
 @AnnotatedFor({"nullness"})
 @GwtCompatible(emulated = true)
+@ElementTypesAreNonnullByDefault
 public final class Lists {
   private Lists() {}
 
@@ -77,12 +79,12 @@ private Lists() {}
    *
    * <p><b>Note:</b> if mutability is not required, use {@link ImmutableList#of()} instead.
    *
-   * <p><b>Note for Java 7 and later:</b> this method is now unnecessary and should be treated as
-   * deprecated. Instead, use the {@code ArrayList} {@linkplain ArrayList#ArrayList() constructor}
-   * directly, taking advantage of the new <a href="http://goo.gl/iz2Wi">"diamond" syntax</a>.
+   * <p><b>Note:</b> this method is now unnecessary and should be treated as deprecated. Instead,
+   * use the {@code ArrayList} {@linkplain ArrayList#ArrayList() constructor} directly, taking
+   * advantage of <a href="http://goo.gl/iz2Wi">"diamond" syntax</a>.
    */
   @GwtCompatible(serializable = true)
-  public static <E> ArrayList<E> newArrayList() {
+  public static <E extends @Nullable Object> ArrayList<E> newArrayList() {
     return new ArrayList<>();
   }
 
@@ -102,7 +104,7 @@ public static <E> ArrayList<E> newArrayList() {
    */
   @SafeVarargs
   @GwtCompatible(serializable = true)
-  public static <E> ArrayList<E> newArrayList(E... elements) {
+  public static <E extends @Nullable Object> ArrayList<E> newArrayList(E... elements) {
     checkNotNull(elements); // for GWT
     // Avoid integer overflow when a large array is passed in
     int capacity = computeArrayListCapacity(elements.length);
@@ -119,13 +121,13 @@ public static <E> ArrayList<E> newArrayList(E... elements) {
    * ImmutableList#copyOf(Iterable)} instead. (Or, change {@code elements} to be a {@link
    * FluentIterable} and call {@code elements.toList()}.)
    *
-   * <p><b>Note for Java 7 and later:</b> if {@code elements} is a {@link Collection}, you don't
-   * need this method. Use the {@code ArrayList} {@linkplain ArrayList#ArrayList(Collection)
-   * constructor} directly, taking advantage of the new <a href="http://goo.gl/iz2Wi">"diamond"
-   * syntax</a>.
+   * <p><b>Note:</b> if {@code elements} is a {@link Collection}, you don't need this method. Use
+   * the {@code ArrayList} {@linkplain ArrayList#ArrayList(Collection) constructor} directly, taking
+   * advantage of <a href="http://goo.gl/iz2Wi">"diamond" syntax</a>.
    */
   @GwtCompatible(serializable = true)
-  public static <E> ArrayList<E> newArrayList(Iterable<? extends E> elements) {
+  public static <E extends @Nullable Object> ArrayList<E> newArrayList(
+      Iterable<? extends E> elements) {
     checkNotNull(elements); // for GWT
     // Let ArrayList's sizing logic work, if possible
     return (elements instanceof Collection)
@@ -141,7 +143,8 @@ public static <E> ArrayList<E> newArrayList(Iterable<? extends E> elements) {
    * ImmutableList#copyOf(Iterator)} instead.
    */
   @GwtCompatible(serializable = true)
-  public static <E> ArrayList<E> newArrayList(Iterator<? extends E> elements) {
+  public static <E extends @Nullable Object> ArrayList<E> newArrayList(
+      Iterator<? extends E> elements) {
     ArrayList<E> list = newArrayList();
     Iterators.addAll(list, elements);
     return list;
@@ -159,11 +162,11 @@ static int computeArrayListCapacity(int arraySize) {
    * Creates an {@code ArrayList} instance backed by an array with the specified initial size;
    * simply delegates to {@link ArrayList#ArrayList(int)}.
    *
-   * <p><b>Note for Java 7 and later:</b> this method is now unnecessary and should be treated as
-   * deprecated. Instead, use {@code new }{@link ArrayList#ArrayList(int) ArrayList}{@code <>(int)}
-   * directly, taking advantage of the new <a href="http://goo.gl/iz2Wi">"diamond" syntax</a>.
-   * (Unlike here, there is no risk of overload ambiguity, since the {@code ArrayList} constructors
-   * very wisely did not accept varargs.)
+   * <p><b>Note:</b> this method is now unnecessary and should be treated as deprecated. Instead,
+   * use {@code new }{@link ArrayList#ArrayList(int) ArrayList}{@code <>(int)} directly, taking
+   * advantage of <a href="http://goo.gl/iz2Wi">"diamond" syntax</a>. (Unlike here, there is no risk
+   * of overload ambiguity, since the {@code ArrayList} constructors very wisely did not accept
+   * varargs.)
    *
    * @param initialArraySize the exact size of the initial backing array for the returned array list
    *     ({@code ArrayList} documentation calls this value the "capacity")
@@ -172,7 +175,8 @@ static int computeArrayListCapacity(int arraySize) {
    * @throws IllegalArgumentException if {@code initialArraySize} is negative
    */
   @GwtCompatible(serializable = true)
-  public static <E> ArrayList<E> newArrayListWithCapacity(int initialArraySize) {
+  public static <E extends @Nullable Object> ArrayList<E> newArrayListWithCapacity(
+      int initialArraySize) {
     checkNonnegative(initialArraySize, "initialArraySize"); // for GWT.
     return new ArrayList<>(initialArraySize);
   }
@@ -191,7 +195,8 @@ public static <E> ArrayList<E> newArrayListWithCapacity(int initialArraySize) {
    * @throws IllegalArgumentException if {@code estimatedSize} is negative
    */
   @GwtCompatible(serializable = true)
-  public static <E> ArrayList<E> newArrayListWithExpectedSize(int estimatedSize) {
+  public static <E extends @Nullable Object> ArrayList<E> newArrayListWithExpectedSize(
+      int estimatedSize) {
     return new ArrayList<>(computeArrayListCapacity(estimatedSize));
   }
 
@@ -207,13 +212,12 @@ public static <E> ArrayList<E> newArrayListWithExpectedSize(int estimatedSize) {
    * outperform {@code LinkedList} except in certain rare and specific situations. Unless you have
    * spent a lot of time benchmarking your specific needs, use one of those instead.
    *
-   * <p><b>Note for Java 7 and later:</b> this method is now unnecessary and should be treated as
-   * deprecated. Instead, use the {@code LinkedList} {@linkplain LinkedList#LinkedList()
-   * constructor} directly, taking advantage of the new <a href="http://goo.gl/iz2Wi">"diamond"
-   * syntax</a>.
+   * <p><b>Note:</b> this method is now unnecessary and should be treated as deprecated. Instead,
+   * use the {@code LinkedList} {@linkplain LinkedList#LinkedList() constructor} directly, taking
+   * advantage of <a href="http://goo.gl/iz2Wi">"diamond" syntax</a>.
    */
   @GwtCompatible(serializable = true)
-  public static <E> LinkedList<E> newLinkedList() {
+  public static <E extends @Nullable Object> LinkedList<E> newLinkedList() {
     return new LinkedList<>();
   }
 
@@ -229,13 +233,13 @@ public static <E> LinkedList<E> newLinkedList() {
    * outperform {@code LinkedList} except in certain rare and specific situations. Unless you have
    * spent a lot of time benchmarking your specific needs, use one of those instead.
    *
-   * <p><b>Note for Java 7 and later:</b> if {@code elements} is a {@link Collection}, you don't
-   * need this method. Use the {@code LinkedList} {@linkplain LinkedList#LinkedList(Collection)
-   * constructor} directly, taking advantage of the new <a href="http://goo.gl/iz2Wi">"diamond"
-   * syntax</a>.
+   * <p><b>Note:</b> if {@code elements} is a {@link Collection}, you don't need this method. Use
+   * the {@code LinkedList} {@linkplain LinkedList#LinkedList(Collection) constructor} directly,
+   * taking advantage of <a href="http://goo.gl/iz2Wi">"diamond" syntax</a>.
    */
   @GwtCompatible(serializable = true)
-  public static <E> LinkedList<E> newLinkedList(Iterable<? extends E> elements) {
+  public static <E extends @Nullable Object> LinkedList<E> newLinkedList(
+      Iterable<? extends E> elements) {
     LinkedList<E> list = newLinkedList();
     Iterables.addAll(list, elements);
     return list;
@@ -251,7 +255,7 @@ public static <E> LinkedList<E> newLinkedList(Iterable<? extends E> elements) {
    * @since 12.0
    */
   @GwtIncompatible // CopyOnWriteArrayList
-  public static <E> CopyOnWriteArrayList<E> newCopyOnWriteArrayList() {
+  public static <E extends @Nullable Object> CopyOnWriteArrayList<E> newCopyOnWriteArrayList() {
     return new CopyOnWriteArrayList<>();
   }
 
@@ -263,7 +267,7 @@ public static <E> CopyOnWriteArrayList<E> newCopyOnWriteArrayList() {
    * @since 12.0
    */
   @GwtIncompatible // CopyOnWriteArrayList
-  public static <E> CopyOnWriteArrayList<E> newCopyOnWriteArrayList(
+  public static <E extends @Nullable Object> CopyOnWriteArrayList<E> newCopyOnWriteArrayList(
       Iterable<? extends E> elements) {
     // We copy elements to an ArrayList first, rather than incurring the
     // quadratic cost of adding them to the COWAL directly.
@@ -288,7 +292,7 @@ public static <E> CopyOnWriteArrayList<E> newCopyOnWriteArrayList(
    * @param rest an array of additional elements, possibly empty
    * @return an unmodifiable list containing the specified elements
    */
-  public static <E> List<E> asList(@Nullable E first, E[] rest) {
+  public static <E extends @Nullable Object> List<E> asList(@ParametricNullness E first, E[] rest) {
     return new OnePlusArrayList<>(first, rest);
   }
 
@@ -308,17 +312,18 @@ public static <E> List<E> asList(@Nullable E first, E[] rest) {
    * @param rest an array of additional elements, possibly empty
    * @return an unmodifiable list containing the specified elements
    */
-  public static <E> List<E> asList(@Nullable E first, @Nullable E second, E[] rest) {
+  public static <E extends @Nullable Object> List<E> asList(
+      @ParametricNullness E first, @ParametricNullness E second, E[] rest) {
     return new TwoPlusArrayList<>(first, second, rest);
   }
 
   /** @see Lists#asList(Object, Object[]) */
-  private static class OnePlusArrayList<E> extends AbstractList<E>
+  private static class OnePlusArrayList<E extends @Nullable Object> extends AbstractList<E>
       implements Serializable, RandomAccess {
-    final @Nullable E first;
+    @ParametricNullness final E first;
     final E[] rest;
 
-    OnePlusArrayList(@Nullable E first, E[] rest) {
+    OnePlusArrayList(@ParametricNullness E first, E[] rest) {
       this.first = first;
       this.rest = checkNotNull(rest);
     }
@@ -330,6 +335,7 @@ public int size() {
     }
 
     @Override
+    @ParametricNullness
     public E get(int index) {
       // check explicitly so the IOOBE will have the right message
       checkElementIndex(index, size());
@@ -340,13 +346,13 @@ public E get(int index) {
   }
 
   /** @see Lists#asList(Object, Object, Object[]) */
-  private static class TwoPlusArrayList<E> extends AbstractList<E>
+  private static class TwoPlusArrayList<E extends @Nullable Object> extends AbstractList<E>
       implements Serializable, RandomAccess {
-    final @Nullable E first;
-    final @Nullable E second;
+    @ParametricNullness final E first;
+    @ParametricNullness final E second;
     final E[] rest;
 
-    TwoPlusArrayList(@Nullable E first, @Nullable E second, E[] rest) {
+    TwoPlusArrayList(@ParametricNullness E first, @ParametricNullness E second, E[] rest) {
       this.first = first;
       this.second = second;
       this.rest = checkNotNull(rest);
@@ -359,6 +365,7 @@ public int size() {
     }
 
     @Override
+    @ParametricNullness
     public E get(int index) {
       switch (index) {
         case 0:
@@ -524,7 +531,7 @@ public static <B> List<List<B>> cartesianProduct(List<? extends B>... lists) {
    * java.util.stream.Stream#map}. This method is not being deprecated, but we gently encourage you
    * to migrate to streams.
    */
-  public static <F, T> List<T> transform(
+  public static <F extends @Nullable Object, T extends @Nullable Object> List<T> transform(
       List<F> fromList, Function<? super F, ? extends T> function) {
     return (fromList instanceof RandomAccess)
         ? new TransformingRandomAccessList<>(fromList, function)
@@ -536,8 +543,9 @@ public static <F, T> List<T> transform(
    *
    * @see Lists#transform
    */
-  private static class TransformingSequentialList<F, T> extends AbstractSequentialList<T>
-      implements Serializable {
+  private static class TransformingSequentialList<
+          F extends @Nullable Object, T extends @Nullable Object>
+      extends AbstractSequentialList<T> implements Serializable {
     final List<F> fromList;
     final Function<? super F, ? extends T> function;
 
@@ -565,7 +573,8 @@ public int size() {
     public ListIterator<T> listIterator(final int index) {
       return new TransformedListIterator<F, T>(fromList.listIterator(index)) {
         @Override
-        T transform(F from) {
+        @ParametricNullness
+        T transform(@ParametricNullness F from) {
           return function.apply(from);
         }
       };
@@ -587,8 +596,9 @@ public boolean removeIf(Predicate<? super T> filter) {
    *
    * @see Lists#transform
    */
-  private static class TransformingRandomAccessList<F, T> extends AbstractList<T>
-      implements RandomAccess, Serializable {
+  private static class TransformingRandomAccessList<
+          F extends @Nullable Object, T extends @Nullable Object>
+      extends AbstractList<T> implements RandomAccess, Serializable {
     final List<F> fromList;
     final Function<? super F, ? extends T> function;
 
@@ -603,6 +613,7 @@ public void clear() {
     }
 
     @Override
+    @ParametricNullness
     public T get(int index) {
       return function.apply(fromList.get(index));
     }
@@ -635,6 +646,7 @@ public boolean removeIf(Predicate<? super T> filter) {
     }
 
     @Override
+    @ParametricNullness
     public T remove(int index) {
       return function.apply(fromList.remove(index));
     }
@@ -663,7 +675,7 @@ public int size() {
    * @return a list of consecutive sublists
    * @throws IllegalArgumentException if {@code partitionSize} is nonpositive
    */
-  public static <T> List<List<T>> partition(List<T> list, int size) {
+  public static <T extends @Nullable Object> List<List<T>> partition(List<T> list, int size) {
     checkNotNull(list);
     checkArgument(size > 0);
     return (list instanceof RandomAccess)
@@ -671,7 +683,7 @@ public static <T> List<List<T>> partition(List<T> list, int size) {
         : new Partition<>(list, size);
   }
 
-  private static class Partition<T> extends AbstractList<List<T>> {
+  private static class Partition<T extends @Nullable Object> extends AbstractList<List<T>> {
     final List<T> list;
     final int size;
 
@@ -701,7 +713,8 @@ public boolean isEmpty() {
     }
   }
 
-  private static class RandomAccessPartition<T> extends Partition<T> implements RandomAccess {
+  private static class RandomAccessPartition<T extends @Nullable Object> extends Partition<T>
+      implements RandomAccess {
     RandomAccessPartition(List<T> list, int size) {
       super(list, size);
     }
@@ -740,12 +753,12 @@ private static final class StringAsImmutableList extends ImmutableList<Character
     }
 
     @Override
-    public int indexOf(@Nullable Object object) {
+    public int indexOf(@CheckForNull Object object) {
       return (object instanceof Character) ? string.indexOf((Character) object) : -1;
     }
 
     @Override
-    public int lastIndexOf(@Nullable Object object) {
+    public int lastIndexOf(@CheckForNull Object object) {
       return (object instanceof Character) ? string.lastIndexOf((Character) object) : -1;
     }
 
@@ -802,9 +815,13 @@ public int size() {
    *
    * @since 7.0
    */
-  public static <T> List<T> reverse(List<T> list) {
+  public static <T extends @Nullable Object> List<T> reverse(List<T> list) {
     if (list instanceof ImmutableList) {
-      return ((ImmutableList<T>) list).reverse();
+      // Avoid nullness warnings.
+      List<?> reversed = ((ImmutableList<?>) list).reverse();
+      @SuppressWarnings("unchecked")
+      List<T> result = (List<T>) reversed;
+      return result;
     } else if (list instanceof ReverseList) {
       return ((ReverseList<T>) list).getForwardList();
     } else if (list instanceof RandomAccess) {
@@ -814,7 +831,7 @@ public static <T> List<T> reverse(List<T> list) {
     }
   }
 
-  private static class ReverseList<T> extends AbstractList<T> {
+  private static class ReverseList<T extends @Nullable Object> extends AbstractList<T> {
     private final List<T> forwardList;
 
     ReverseList(List<T> forwardList) {
@@ -838,7 +855,7 @@ private int reversePosition(int index) {
     }
 
     @Override
-    public void add(int index, @Nullable T element) {
+    public void add(int index, @ParametricNullness T element) {
       forwardList.add(reversePosition(index), element);
     }
 
@@ -848,6 +865,7 @@ public void clear() {
     }
 
     @Override
+    @ParametricNullness
     public T remove(int index) {
       return forwardList.remove(reverseIndex(index));
     }
@@ -858,11 +876,13 @@ protected void removeRange(int fromIndex, int toIndex) {
     }
 
     @Override
-    public T set(int index, @Nullable T element) {
+    @ParametricNullness
+    public T set(int index, @ParametricNullness T element) {
       return forwardList.set(reverseIndex(index), element);
     }
 
     @Override
+    @ParametricNullness
     public T get(int index) {
       return forwardList.get(reverseIndex(index));
     }
@@ -892,7 +912,7 @@ public ListIterator<T> listIterator(int index) {
         boolean canRemoveOrSet;
 
         @Override
-        public void add(T e) {
+        public void add(@ParametricNullness T e) {
           forwardIterator.add(e);
           forwardIterator.previous();
           canRemoveOrSet = false;
@@ -909,6 +929,7 @@ public boolean hasPrevious() {
         }
 
         @Override
+        @ParametricNullness
         public T next() {
           if (!hasNext()) {
             throw new NoSuchElementException();
@@ -923,6 +944,7 @@ public int nextIndex() {
         }
 
         @Override
+        @ParametricNullness
         public T previous() {
           if (!hasPrevious()) {
             throw new NoSuchElementException();
@@ -944,7 +966,7 @@ public void remove() {
         }
 
         @Override
-        public void set(T e) {
+        public void set(@ParametricNullness T e) {
           checkState(canRemoveOrSet);
           forwardIterator.set(e);
         }
@@ -952,7 +974,8 @@ public void set(T e) {
     }
   }
 
-  private static class RandomAccessReverseList<T> extends ReverseList<T> implements RandomAccess {
+  private static class RandomAccessReverseList<T extends @Nullable Object> extends ReverseList<T>
+      implements RandomAccess {
     RandomAccessReverseList(List<T> forwardList) {
       super(forwardList);
     }
@@ -972,7 +995,7 @@ static int hashCodeImpl(List<?> list) {
   }
 
   /** An implementation of {@link List#equals(Object)}. */
-  static boolean equalsImpl(List<?> thisList, @Nullable Object other) {
+  static boolean equalsImpl(List<?> thisList, @CheckForNull Object other) {
     if (other == checkNotNull(thisList)) {
       return true;
     }
@@ -998,7 +1021,8 @@ static boolean equalsImpl(List<?> thisList, @Nullable Object other) {
   }
 
   /** An implementation of {@link List#addAll(int, Collection)}. */
-  static <E> boolean addAllImpl(List<E> list, int index, Iterable<? extends E> elements) {
+  static <E extends @Nullable Object> boolean addAllImpl(
+      List<E> list, int index, Iterable<? extends E> elements) {
     boolean changed = false;
     ListIterator<E> listIterator = list.listIterator(index);
     for (E e : elements) {
@@ -1009,7 +1033,7 @@ static <E> boolean addAllImpl(List<E> list, int index, Iterable<? extends E> ele
   }
 
   /** An implementation of {@link List#indexOf(Object)}. */
-  static int indexOfImpl(List<?> list, @Nullable Object element) {
+  static int indexOfImpl(List<?> list, @CheckForNull Object element) {
     if (list instanceof RandomAccess) {
       return indexOfRandomAccess(list, element);
     } else {
@@ -1023,7 +1047,7 @@ static int indexOfImpl(List<?> list, @Nullable Object element) {
     }
   }
 
-  private static int indexOfRandomAccess(List<?> list, @Nullable Object element) {
+  private static int indexOfRandomAccess(List<?> list, @CheckForNull Object element) {
     int size = list.size();
     if (element == null) {
       for (int i = 0; i < size; i++) {
@@ -1042,7 +1066,7 @@ private static int indexOfRandomAccess(List<?> list, @Nullable Object element) {
   }
 
   /** An implementation of {@link List#lastIndexOf(Object)}. */
-  static int lastIndexOfImpl(List<?> list, @Nullable Object element) {
+  static int lastIndexOfImpl(List<?> list, @CheckForNull Object element) {
     if (list instanceof RandomAccess) {
       return lastIndexOfRandomAccess(list, element);
     } else {
@@ -1056,7 +1080,7 @@ static int lastIndexOfImpl(List<?> list, @Nullable Object element) {
     }
   }
 
-  private static int lastIndexOfRandomAccess(List<?> list, @Nullable Object element) {
+  private static int lastIndexOfRandomAccess(List<?> list, @CheckForNull Object element) {
     if (element == null) {
       for (int i = list.size() - 1; i >= 0; i--) {
         if (list.get(i) == null) {
@@ -1074,12 +1098,13 @@ private static int lastIndexOfRandomAccess(List<?> list, @Nullable Object elemen
   }
 
   /** Returns an implementation of {@link List#listIterator(int)}. */
-  static <E> ListIterator<E> listIteratorImpl(List<E> list, int index) {
+  static <E extends @Nullable Object> ListIterator<E> listIteratorImpl(List<E> list, int index) {
     return new AbstractListWrapper<>(list).listIterator(index);
   }
 
   /** An implementation of {@link List#subList(int, int)}. */
-  static <E> List<E> subListImpl(final List<E> list, int fromIndex, int toIndex) {
+  static <E extends @Nullable Object> List<E> subListImpl(
+      final List<E> list, int fromIndex, int toIndex) {
     List<E> wrapper;
     if (list instanceof RandomAccess) {
       wrapper =
@@ -1105,7 +1130,7 @@ public ListIterator<E> listIterator(int index) {
     return wrapper.subList(fromIndex, toIndex);
   }
 
-  private static class AbstractListWrapper<E> extends AbstractList<E> {
+  private static class AbstractListWrapper<E extends @Nullable Object> extends AbstractList<E> {
     final List<E> backingList;
 
     AbstractListWrapper(List<E> backingList) {
@@ -1113,7 +1138,7 @@ private static class AbstractListWrapper<E> extends AbstractList<E> {
     }
 
     @Override
-    public void add(int index, E element) {
+    public void add(int index, @ParametricNullness E element) {
       backingList.add(index, element);
     }
 
@@ -1123,22 +1148,25 @@ public boolean addAll(int index, Collection<? extends E> c) {
     }
 
     @Override
+    @ParametricNullness
     public E get(int index) {
       return backingList.get(index);
     }
 
     @Override
+    @ParametricNullness
     public E remove(int index) {
       return backingList.remove(index);
     }
 
     @Override
-    public E set(int index, E element) {
+    @ParametricNullness
+    public E set(int index, @ParametricNullness E element) {
       return backingList.set(index, element);
     }
 
     @Override
-    public boolean contains(Object o) {
+    public boolean contains(@CheckForNull Object o) {
       return backingList.contains(o);
     }
 
@@ -1148,15 +1176,15 @@ public int size() {
     }
   }
 
-  private static class RandomAccessListWrapper<E> extends AbstractListWrapper<E>
-      implements RandomAccess {
+  private static class RandomAccessListWrapper<E extends @Nullable Object>
+      extends AbstractListWrapper<E> implements RandomAccess {
     RandomAccessListWrapper(List<E> backingList) {
       super(backingList);
     }
   }
 
   /** Used to avoid http://bugs.sun.com/view_bug.do?bug_id=6558557 */
-  static <T> List<T> cast(Iterable<T> iterable) {
+  static <T extends @Nullable Object> List<T> cast(Iterable<T> iterable) {
     return (List<T>) iterable;
   }
 }
diff --git a/guava/src/com/google/common/collect/MapDifference.java b/guava/src/com/google/common/collect/MapDifference.java
index 6e829acf753d..4ff4e9cc6f91 100644
--- a/guava/src/com/google/common/collect/MapDifference.java
+++ b/guava/src/com/google/common/collect/MapDifference.java
@@ -19,6 +19,7 @@
 import com.google.common.annotations.GwtCompatible;
 import com.google.errorprone.annotations.DoNotMock;
 import java.util.Map;
+import javax.annotation.CheckForNull;
 import org.checkerframework.checker.nullness.qual.Nullable;
 import org.checkerframework.dataflow.qual.Pure;
 import org.checkerframework.framework.qual.AnnotatedFor;
@@ -32,7 +33,8 @@
 @DoNotMock("Use Maps.difference")
 @GwtCompatible
 @AnnotatedFor({"nullness"})
-public interface MapDifference<K, V> {
+@ElementTypesAreNonnullByDefault
+public interface MapDifference<K extends @Nullable Object, V extends @Nullable Object> {
   /**
    * Returns {@code true} if there are no differences between the two maps; that is, if the maps are
    * equal.
@@ -71,7 +73,7 @@ public interface MapDifference<K, V> {
    */
   @Pure
   @Override
-  boolean equals(@Nullable Object object);
+  boolean equals(@CheckForNull Object object);
 
   /**
    * Returns the hash code for this instance. This is defined as the hash code of
@@ -92,11 +94,13 @@ public interface MapDifference<K, V> {
    * @since 2.0
    */
   @DoNotMock("Use Maps.difference")
-  interface ValueDifference<V> {
+  interface ValueDifference<V extends @Nullable Object> {
     /** Returns the value from the left map (possibly null). */
+    @ParametricNullness
     V leftValue();
 
     /** Returns the value from the right map (possibly null). */
+    @ParametricNullness
     V rightValue();
 
     /**
@@ -105,7 +109,7 @@ interface ValueDifference<V> {
      */
     @Pure
     @Override
-    boolean equals(@Nullable Object other);
+    boolean equals(@CheckForNull Object other);
 
     /**
      * The hash code equals the value {@code Arrays.asList(leftValue(), rightValue()).hashCode()}.
diff --git a/guava/src/com/google/common/collect/MapMaker.java b/guava/src/com/google/common/collect/MapMaker.java
index 8730adfe3ab3..7f68df0aee19 100644
--- a/guava/src/com/google/common/collect/MapMaker.java
+++ b/guava/src/com/google/common/collect/MapMaker.java
@@ -30,6 +30,7 @@
 import java.util.Map;
 import java.util.concurrent.ConcurrentHashMap;
 import java.util.concurrent.ConcurrentMap;
+import javax.annotation.CheckForNull;
 import org.checkerframework.checker.nullness.qual.MonotonicNonNull;
 import org.checkerframework.checker.nullness.qual.Nullable;
 import org.checkerframework.framework.qual.AnnotatedFor;
@@ -89,6 +90,7 @@
  */
 @AnnotatedFor({"nullness"})
 @GwtCompatible(emulated = true)
+@ElementTypesAreNonnullByDefault
 public final class MapMaker {
   private static final int DEFAULT_INITIAL_CAPACITY = 16;
   private static final int DEFAULT_CONCURRENCY_LEVEL = 4;
@@ -101,10 +103,10 @@ public final class MapMaker {
   int initialCapacity = UNSET_INT;
   int concurrencyLevel = UNSET_INT;
 
-  @Nullable Strength keyStrength;
-  @Nullable Strength valueStrength;
+  @CheckForNull Strength keyStrength;
+  @CheckForNull Strength valueStrength;
 
-  @Nullable Equivalence<Object> keyEquivalence;
+  @CheckForNull Equivalence<Object> keyEquivalence;
 
   /**
    * Constructs a new {@code MapMaker} instance with default settings, including strong keys, strong
diff --git a/guava/src/com/google/common/collect/MapMakerInternalMap.java b/guava/src/com/google/common/collect/MapMakerInternalMap.java
index b647f7612902..3725d9723b00 100644
--- a/guava/src/com/google/common/collect/MapMakerInternalMap.java
+++ b/guava/src/com/google/common/collect/MapMakerInternalMap.java
@@ -65,7 +65,11 @@
  */
 // TODO(kak): Consider removing @CanIgnoreReturnValue from this class.
 @GwtIncompatible
-@SuppressWarnings("GuardedBy") // TODO(b/35466881): Fix or suppress.
+@SuppressWarnings({
+  "GuardedBy", // TODO(b/35466881): Fix or suppress.
+  "nullness", // too much trouble for the payoff
+})
+// TODO(cpovirk): Annotate for nullness.
 class MapMakerInternalMap<
         K,
         V,
diff --git a/guava/src/com/google/common/collect/Maps.java b/guava/src/com/google/common/collect/Maps.java
index c13a43727032..90785d0cba4c 100644
--- a/guava/src/com/google/common/collect/Maps.java
+++ b/guava/src/com/google/common/collect/Maps.java
@@ -21,6 +21,8 @@
 import static com.google.common.base.Predicates.compose;
 import static com.google.common.collect.CollectPreconditions.checkEntryNotNull;
 import static com.google.common.collect.CollectPreconditions.checkNonnegative;
+import static com.google.common.collect.NullnessCasts.uncheckedCastNullableTToT;
+import static java.util.Objects.requireNonNull;
 
 import com.google.common.annotations.Beta;
 import com.google.common.annotations.GwtCompatible;
@@ -68,6 +70,7 @@
 import java.util.function.BinaryOperator;
 import java.util.function.Consumer;
 import java.util.stream.Collector;
+import javax.annotation.CheckForNull;
 import org.checkerframework.checker.nullness.qual.Nullable;
 import org.checkerframework.dataflow.qual.Pure;
 import org.checkerframework.dataflow.qual.SideEffectFree;
@@ -79,7 +82,7 @@
  * and {@link Queues}.
  *
  * <p>See the Guava User Guide article on <a href=
- * "https://github.com/google/guava/wiki/CollectionUtilitiesExplained#maps"> {@code Maps}</a>.
+ * "https://github.com/google/guava/wiki/CollectionUtilitiesExplained#maps">{@code Maps}</a>.
  *
  * @author Kevin Bourrillion
  * @author Mike Bostock
@@ -89,46 +92,53 @@
  */
 @AnnotatedFor({"nullness"})
 @GwtCompatible(emulated = true)
+@ElementTypesAreNonnullByDefault
 public final class Maps {
   private Maps() {}
 
-  private enum EntryFunction implements Function<Entry<?, ?>, Object> {
+  private enum EntryFunction implements Function<Entry<?, ?>, @Nullable Object> {
     KEY {
       @Override
-      public @Nullable Object apply(Entry<?, ?> entry) {
+      @CheckForNull
+      public Object apply(Entry<?, ?> entry) {
         return entry.getKey();
       }
     },
     VALUE {
       @Override
-      public @Nullable Object apply(Entry<?, ?> entry) {
+      @CheckForNull
+      public Object apply(Entry<?, ?> entry) {
         return entry.getValue();
       }
     };
   }
 
   @SuppressWarnings("unchecked")
-  static <K> Function<Entry<K, ?>, K> keyFunction() {
+  static <K extends @Nullable Object> Function<Entry<K, ?>, K> keyFunction() {
     return (Function) EntryFunction.KEY;
   }
 
   @SuppressWarnings("unchecked")
-  static <V> Function<Entry<?, V>, V> valueFunction() {
+  static <V extends @Nullable Object> Function<Entry<?, V>, V> valueFunction() {
     return (Function) EntryFunction.VALUE;
   }
 
-  static <K, V> Iterator<K> keyIterator(Iterator<Entry<K, V>> entryIterator) {
+  static <K extends @Nullable Object, V extends @Nullable Object> Iterator<K> keyIterator(
+      Iterator<Entry<K, V>> entryIterator) {
     return new TransformedIterator<Entry<K, V>, K>(entryIterator) {
       @Override
+      @ParametricNullness
       K transform(Entry<K, V> entry) {
         return entry.getKey();
       }
     };
   }
 
-  static <K, V> Iterator<V> valueIterator(Iterator<Entry<K, V>> entryIterator) {
+  static <K extends @Nullable Object, V extends @Nullable Object> Iterator<V> valueIterator(
+      Iterator<Entry<K, V>> entryIterator) {
     return new TransformedIterator<Entry<K, V>, V>(entryIterator) {
       @Override
+      @ParametricNullness
       V transform(Entry<K, V> entry) {
         return entry.getValue();
       }
@@ -189,9 +199,10 @@ public static <K extends Enum<K>, V> ImmutableMap<K, V> immutableEnumMap(
    *
    * @since 21.0
    */
-  public static <T, K extends Enum<K>, V> Collector<T, ?, ImmutableMap<K, V>> toImmutableEnumMap(
-      java.util.function.Function<? super T, ? extends K> keyFunction,
-      java.util.function.Function<? super T, ? extends V> valueFunction) {
+  public static <T extends @Nullable Object, K extends Enum<K>, V>
+      Collector<T, ?, ImmutableMap<K, V>> toImmutableEnumMap(
+          java.util.function.Function<? super T, ? extends K> keyFunction,
+          java.util.function.Function<? super T, ? extends V> valueFunction) {
     return CollectCollectors.toImmutableEnumMap(keyFunction, valueFunction);
   }
 
@@ -206,10 +217,11 @@ public static <K extends Enum<K>, V> ImmutableMap<K, V> immutableEnumMap(
    *
    * @since 21.0
    */
-  public static <T, K extends Enum<K>, V> Collector<T, ?, ImmutableMap<K, V>> toImmutableEnumMap(
-      java.util.function.Function<? super T, ? extends K> keyFunction,
-      java.util.function.Function<? super T, ? extends V> valueFunction,
-      BinaryOperator<V> mergeFunction) {
+  public static <T extends @Nullable Object, K extends Enum<K>, V>
+      Collector<T, ?, ImmutableMap<K, V>> toImmutableEnumMap(
+          java.util.function.Function<? super T, ? extends K> keyFunction,
+          java.util.function.Function<? super T, ? extends V> valueFunction,
+          BinaryOperator<V> mergeFunction) {
     return CollectCollectors.toImmutableEnumMap(keyFunction, valueFunction, mergeFunction);
   }
 
@@ -220,13 +232,14 @@ public static <K extends Enum<K>, V> ImmutableMap<K, V> immutableEnumMap(
    *
    * <p><b>Note:</b> if {@code K} is an {@code enum} type, use {@link #newEnumMap} instead.
    *
-   * <p><b>Note for Java 7 and later:</b> this method is now unnecessary and should be treated as
-   * deprecated. Instead, use the {@code HashMap} constructor directly, taking advantage of the new
-   * <a href="http://goo.gl/iz2Wi">"diamond" syntax</a>.
+   * <p><b>Note:</b> this method is now unnecessary and should be treated as deprecated. Instead,
+   * use the {@code HashMap} constructor directly, taking advantage of <a
+   * href="http://goo.gl/iz2Wi">"diamond" syntax</a>.
    *
    * @return a new, empty {@code HashMap}
    */
-  public static <K, V> HashMap<K, V> newHashMap() {
+  public static <K extends @Nullable Object, V extends @Nullable Object>
+      HashMap<K, V> newHashMap() {
     return new HashMap<>();
   }
 
@@ -237,14 +250,15 @@ public static <K, V> HashMap<K, V> newHashMap() {
    *
    * <p><b>Note:</b> if {@code K} is an {@link Enum} type, use {@link #newEnumMap} instead.
    *
-   * <p><b>Note for Java 7 and later:</b> this method is now unnecessary and should be treated as
-   * deprecated. Instead, use the {@code HashMap} constructor directly, taking advantage of the new
-   * <a href="http://goo.gl/iz2Wi">"diamond" syntax</a>.
+   * <p><b>Note:</b> this method is now unnecessary and should be treated as deprecated. Instead,
+   * use the {@code HashMap} constructor directly, taking advantage of <a
+   * href="http://goo.gl/iz2Wi">"diamond" syntax</a>.
    *
    * @param map the mappings to be placed in the new map
    * @return a new {@code HashMap} initialized with the mappings from {@code map}
    */
-  public static <K, V> HashMap<K, V> newHashMap(Map<? extends K, ? extends V> map) {
+  public static <K extends @Nullable Object, V extends @Nullable Object> HashMap<K, V> newHashMap(
+      Map<? extends K, ? extends V> map) {
     return new HashMap<>(map);
   }
 
@@ -259,7 +273,8 @@ public static <K, V> HashMap<K, V> newHashMap(Map<? extends K, ? extends V> map)
    *     without resizing
    * @throws IllegalArgumentException if {@code expectedSize} is negative
    */
-  public static <K, V> HashMap<K, V> newHashMapWithExpectedSize(int expectedSize) {
+  public static <K extends @Nullable Object, V extends @Nullable Object>
+      HashMap<K, V> newHashMapWithExpectedSize(int expectedSize) {
     return new HashMap<>(capacity(expectedSize));
   }
 
@@ -286,13 +301,14 @@ static int capacity(int expectedSize) {
    *
    * <p><b>Note:</b> if mutability is not required, use {@link ImmutableMap#of()} instead.
    *
-   * <p><b>Note for Java 7 and later:</b> this method is now unnecessary and should be treated as
-   * deprecated. Instead, use the {@code LinkedHashMap} constructor directly, taking advantage of
-   * the new <a href="http://goo.gl/iz2Wi">"diamond" syntax</a>.
+   * <p><b>Note:</b> this method is now unnecessary and should be treated as deprecated. Instead,
+   * use the {@code LinkedHashMap} constructor directly, taking advantage of <a
+   * href="http://goo.gl/iz2Wi">"diamond" syntax</a>.
    *
    * @return a new, empty {@code LinkedHashMap}
    */
-  public static <K, V> LinkedHashMap<K, V> newLinkedHashMap() {
+  public static <K extends @Nullable Object, V extends @Nullable Object>
+      LinkedHashMap<K, V> newLinkedHashMap() {
     return new LinkedHashMap<>();
   }
 
@@ -302,14 +318,15 @@ public static <K, V> LinkedHashMap<K, V> newLinkedHashMap() {
    *
    * <p><b>Note:</b> if mutability is not required, use {@link ImmutableMap#copyOf(Map)} instead.
    *
-   * <p><b>Note for Java 7 and later:</b> this method is now unnecessary and should be treated as
-   * deprecated. Instead, use the {@code LinkedHashMap} constructor directly, taking advantage of
-   * the new <a href="http://goo.gl/iz2Wi">"diamond" syntax</a>.
+   * <p><b>Note:</b> this method is now unnecessary and should be treated as deprecated. Instead,
+   * use the {@code LinkedHashMap} constructor directly, taking advantage of <a
+   * href="http://goo.gl/iz2Wi">"diamond" syntax</a>.
    *
    * @param map the mappings to be placed in the new map
    * @return a new, {@code LinkedHashMap} initialized with the mappings from {@code map}
    */
-  public static <K, V> LinkedHashMap<K, V> newLinkedHashMap(Map<? extends K, ? extends V> map) {
+  public static <K extends @Nullable Object, V extends @Nullable Object>
+      LinkedHashMap<K, V> newLinkedHashMap(Map<? extends K, ? extends V> map) {
     return new LinkedHashMap<>(map);
   }
 
@@ -325,7 +342,8 @@ public static <K, V> LinkedHashMap<K, V> newLinkedHashMap(Map<? extends K, ? ext
    * @throws IllegalArgumentException if {@code expectedSize} is negative
    * @since 19.0
    */
-  public static <K, V> LinkedHashMap<K, V> newLinkedHashMapWithExpectedSize(int expectedSize) {
+  public static <K extends @Nullable Object, V extends @Nullable Object>
+      LinkedHashMap<K, V> newLinkedHashMapWithExpectedSize(int expectedSize) {
     return new LinkedHashMap<>(capacity(expectedSize));
   }
 
@@ -344,13 +362,13 @@ public static <K, V> ConcurrentMap<K, V> newConcurrentMap() {
    *
    * <p><b>Note:</b> if mutability is not required, use {@link ImmutableSortedMap#of()} instead.
    *
-   * <p><b>Note for Java 7 and later:</b> this method is now unnecessary and should be treated as
-   * deprecated. Instead, use the {@code TreeMap} constructor directly, taking advantage of the new
-   * <a href="http://goo.gl/iz2Wi">"diamond" syntax</a>.
+   * <p><b>Note:</b> this method is now unnecessary and should be treated as deprecated. Instead,
+   * use the {@code TreeMap} constructor directly, taking advantage of <a
+   * href="http://goo.gl/iz2Wi">"diamond" syntax</a>.
    *
    * @return a new, empty {@code TreeMap}
    */
-  public static <K extends @Nullable Comparable, V> TreeMap<K, V> newTreeMap() {
+  public static <K extends Comparable, V extends @Nullable Object> TreeMap<K, V> newTreeMap() {
     return new TreeMap<>();
   }
 
@@ -361,16 +379,17 @@ public static <K, V> ConcurrentMap<K, V> newConcurrentMap() {
    * <p><b>Note:</b> if mutability is not required, use {@link
    * ImmutableSortedMap#copyOfSorted(SortedMap)} instead.
    *
-   * <p><b>Note for Java 7 and later:</b> this method is now unnecessary and should be treated as
-   * deprecated. Instead, use the {@code TreeMap} constructor directly, taking advantage of the new
-   * <a href="http://goo.gl/iz2Wi">"diamond" syntax</a>.
+   * <p><b>Note:</b> this method is now unnecessary and should be treated as deprecated. Instead,
+   * use the {@code TreeMap} constructor directly, taking advantage of <a
+   * href="http://goo.gl/iz2Wi">"diamond" syntax</a>.
    *
    * @param map the sorted map whose mappings are to be placed in the new map and whose comparator
    *     is to be used to sort the new map
    * @return a new {@code TreeMap} initialized with the mappings from {@code map} and using the
    *     comparator of {@code map}
    */
-  public static <K, V> TreeMap<K, V> newTreeMap(SortedMap<K, ? extends V> map) {
+  public static <K extends @Nullable Object, V extends @Nullable Object> TreeMap<K, V> newTreeMap(
+      SortedMap<K, ? extends V> map) {
     return new TreeMap<>(map);
   }
 
@@ -380,14 +399,15 @@ public static <K, V> TreeMap<K, V> newTreeMap(SortedMap<K, ? extends V> map) {
    * <p><b>Note:</b> if mutability is not required, use {@code
    * ImmutableSortedMap.orderedBy(comparator).build()} instead.
    *
-   * <p><b>Note for Java 7 and later:</b> this method is now unnecessary and should be treated as
-   * deprecated. Instead, use the {@code TreeMap} constructor directly, taking advantage of the new
-   * <a href="http://goo.gl/iz2Wi">"diamond" syntax</a>.
+   * <p><b>Note:</b> this method is now unnecessary and should be treated as deprecated. Instead,
+   * use the {@code TreeMap} constructor directly, taking advantage of <a
+   * href="http://goo.gl/iz2Wi">"diamond" syntax</a>.
    *
    * @param comparator the comparator to sort the keys with
    * @return a new, empty {@code TreeMap}
    */
-  public static <C, K extends C, V> TreeMap<K, V> newTreeMap(@Nullable Comparator<C> comparator) {
+  public static <C extends @Nullable Object, K extends C, V extends @Nullable Object>
+      TreeMap<K, V> newTreeMap(@CheckForNull Comparator<C> comparator) {
     // Ideally, the extra type parameter "C" shouldn't be necessary. It is a
     // work-around of a compiler type inference quirk that prevents the
     // following code from being compiled:
@@ -402,36 +422,39 @@ public static <C, K extends C, V> TreeMap<K, V> newTreeMap(@Nullable Comparator<
    * @param type the key type for this map
    * @return a new, empty {@code EnumMap}
    */
-  public static <K extends Enum<K>, V> EnumMap<K, V> newEnumMap(Class<K> type) {
+  public static <K extends Enum<K>, V extends @Nullable Object> EnumMap<K, V> newEnumMap(
+      Class<K> type) {
     return new EnumMap<>(checkNotNull(type));
   }
 
   /**
    * Creates an {@code EnumMap} with the same mappings as the specified map.
    *
-   * <p><b>Note for Java 7 and later:</b> this method is now unnecessary and should be treated as
-   * deprecated. Instead, use the {@code EnumMap} constructor directly, taking advantage of the new
-   * <a href="http://goo.gl/iz2Wi">"diamond" syntax</a>.
+   * <p><b>Note:</b> this method is now unnecessary and should be treated as deprecated. Instead,
+   * use the {@code EnumMap} constructor directly, taking advantage of <a
+   * href="http://goo.gl/iz2Wi">"diamond" syntax</a>.
    *
    * @param map the map from which to initialize this {@code EnumMap}
    * @return a new {@code EnumMap} initialized with the mappings from {@code map}
    * @throws IllegalArgumentException if {@code m} is not an {@code EnumMap} instance and contains
    *     no mappings
    */
-  public static <K extends Enum<K>, V> EnumMap<K, V> newEnumMap(Map<K, ? extends V> map) {
+  public static <K extends Enum<K>, V extends @Nullable Object> EnumMap<K, V> newEnumMap(
+      Map<K, ? extends V> map) {
     return new EnumMap<>(map);
   }
 
   /**
    * Creates an {@code IdentityHashMap} instance.
    *
-   * <p><b>Note for Java 7 and later:</b> this method is now unnecessary and should be treated as
-   * deprecated. Instead, use the {@code IdentityHashMap} constructor directly, taking advantage of
-   * the new <a href="http://goo.gl/iz2Wi">"diamond" syntax</a>.
+   * <p><b>Note:</b> this method is now unnecessary and should be treated as deprecated. Instead,
+   * use the {@code IdentityHashMap} constructor directly, taking advantage of <a
+   * href="http://goo.gl/iz2Wi">"diamond" syntax</a>.
    *
    * @return a new, empty {@code IdentityHashMap}
    */
-  public static <K, V> IdentityHashMap<K, V> newIdentityHashMap() {
+  public static <K extends @Nullable Object, V extends @Nullable Object>
+      IdentityHashMap<K, V> newIdentityHashMap() {
     return new IdentityHashMap<>();
   }
 
@@ -451,13 +474,27 @@ public static <K, V> IdentityHashMap<K, V> newIdentityHashMap() {
    * @return the difference between the two maps
    */
   @SuppressWarnings("unchecked")
-  public static <K, V> MapDifference<K, V> difference(
-      Map<? extends K, ? extends V> left, Map<? extends K, ? extends V> right) {
+  public static <K extends @Nullable Object, V extends @Nullable Object>
+      MapDifference<K, V> difference(
+          Map<? extends K, ? extends V> left, Map<? extends K, ? extends V> right) {
     if (left instanceof SortedMap) {
       SortedMap<K, ? extends V> sortedLeft = (SortedMap<K, ? extends V>) left;
       return difference(sortedLeft, right);
     }
-    return difference(left, right, Equivalence.equals());
+    /*
+     * This cast is safe: The Equivalence-accepting overload of difference() (which we call below)
+     * has a weird signature because Equivalence is itself a little weird. Still, we know that
+     * Equivalence.equals() can handle all inputs, and we know that the resulting MapDifference will
+     * contain only Ks and Vs (as opposed to possibly containing @Nullable objects even when K and V
+     * are *not* @Nullable).
+     *
+     * An alternative to suppressing the warning would be to inline the body of the other
+     * difference() method into this one.
+     */
+    @SuppressWarnings("nullness")
+    MapDifference<K, V> result =
+        (MapDifference<K, V>) difference(left, right, Equivalence.equals());
+    return result;
   }
 
   /**
@@ -474,7 +511,33 @@ public static <K, V> MapDifference<K, V> difference(
    * @return the difference between the two maps
    * @since 10.0
    */
-  public static <K, V> MapDifference<K, V> difference(
+  /*
+   * This method should really be annotated to accept maps with @Nullable value types. Fortunately,
+   * no existing Google callers appear to pass null values (much less pass null values *and* run a
+   * nullness checker).
+   *
+   * Still, if we decide that we want to make that work, we'd need to introduce a new type parameter
+   * for the Equivalence input type:
+   *
+   * <E, K extends @Nullable Object, V extends @Nullable E> ... difference(..., Equivalence<E> ...)
+   *
+   * Maybe we should, even though it will break source compatibility.
+   *
+   * Alternatively, this is a case in which it would be useful to be able to express Equivalence<?
+   * super @Nonnull T>).
+   *
+   * As things stand now, though, we have to either:
+   *
+   * - require non-null inputs so that we can guarantee non-null outputs
+   *
+   * - accept nullable inputs but force users to cope with nullable outputs
+   *
+   * And the non-null option is far more useful to existing users.
+   *
+   * (Vaguely related: Another thing we could consider is an overload that accepts a BiPredicate:
+   * https://github.com/google/guava/issues/3913)
+   */
+  public static <K extends @Nullable Object, V> MapDifference<K, V> difference(
       Map<? extends K, ? extends V> left,
       Map<? extends K, ? extends V> right,
       Equivalence<? super V> valueEquivalence) {
@@ -505,8 +568,9 @@ public static <K, V> MapDifference<K, V> difference(
    * @return the difference between the two maps
    * @since 11.0
    */
-  public static <K, V> SortedMapDifference<K, V> difference(
-      SortedMap<K, ? extends V> left, Map<? extends K, ? extends V> right) {
+  public static <K extends @Nullable Object, V extends @Nullable Object>
+      SortedMapDifference<K, V> difference(
+          SortedMap<K, ? extends V> left, Map<? extends K, ? extends V> right) {
     checkNotNull(left);
     checkNotNull(right);
     Comparator<? super K> comparator = orNaturalOrder(left.comparator());
@@ -515,11 +579,24 @@ public static <K, V> SortedMapDifference<K, V> difference(
     onlyOnRight.putAll(right); // will whittle it down
     SortedMap<K, V> onBoth = Maps.newTreeMap(comparator);
     SortedMap<K, MapDifference.ValueDifference<V>> differences = Maps.newTreeMap(comparator);
-    doDifference(left, right, Equivalence.equals(), onlyOnLeft, onlyOnRight, onBoth, differences);
+
+    /*
+     * V is a possibly nullable type, but we decided to declare Equivalence with a type parameter
+     * that is restricted to non-nullable types. Still, this code is safe: We made that decision
+     * about Equivalence not because Equivalence is null-hostile but because *every* Equivalence can
+     * handle null inputs -- and thus it would be meaningless for the type system to distinguish
+     * between "an Equivalence for nullable Foo" and "an Equivalence for non-nullable Foo."
+     *
+     * (And the unchecked cast is safe because Equivalence is contravariant.)
+     */
+    @SuppressWarnings({"nullness", "unchecked"})
+    Equivalence<V> equalsEquivalence = (Equivalence<V>) Equivalence.equals();
+
+    doDifference(left, right, equalsEquivalence, onlyOnLeft, onlyOnRight, onBoth, differences);
     return new SortedMapDifferenceImpl<>(onlyOnLeft, onlyOnRight, onBoth, differences);
   }
 
-  private static <K, V> void doDifference(
+  private static <K extends @Nullable Object, V extends @Nullable Object> void doDifference(
       Map<? extends K, ? extends V> left,
       Map<? extends K, ? extends V> right,
       Equivalence<? super V> valueEquivalence,
@@ -531,7 +608,17 @@ private static <K, V> void doDifference(
       K leftKey = entry.getKey();
       V leftValue = entry.getValue();
       if (right.containsKey(leftKey)) {
-        V rightValue = onlyOnRight.remove(leftKey);
+        /*
+         * The cast is safe because onlyOnRight contains all the keys of right.
+         *
+         * TODO(cpovirk): Consider checking onlyOnRight.containsKey instead of right.containsKey.
+         * That could change behavior if the input maps use different equivalence relations (and so
+         * a key that appears once in `right` might appear multiple times in `left`). We don't
+         * guarantee behavior in that case, anyway, and the current behavior is likely undesirable.
+         * So that's either a reason to feel free to change it or a reason to not bother thinking
+         * further about this.
+         */
+        V rightValue = uncheckedCastNullableTToT(onlyOnRight.remove(leftKey));
         if (valueEquivalence.equivalent(leftValue, rightValue)) {
           onBoth.put(leftKey, leftValue);
         } else {
@@ -543,7 +630,8 @@ private static <K, V> void doDifference(
     }
   }
 
-  private static <K, V> Map<K, V> unmodifiableMap(Map<K, ? extends V> map) {
+  private static <K extends @Nullable Object, V extends @Nullable Object> Map<K, V> unmodifiableMap(
+      Map<K, ? extends V> map) {
     if (map instanceof SortedMap) {
       return Collections.unmodifiableSortedMap((SortedMap<K, ? extends V>) map);
     } else {
@@ -551,7 +639,8 @@ private static <K, V> Map<K, V> unmodifiableMap(Map<K, ? extends V> map) {
     }
   }
 
-  static class MapDifferenceImpl<K, V> implements MapDifference<K, V> {
+  static class MapDifferenceImpl<K extends @Nullable Object, V extends @Nullable Object>
+      implements MapDifference<K, V> {
     final Map<K, V> onlyOnLeft;
     final Map<K, V> onlyOnRight;
     final Map<K, V> onBoth;
@@ -595,7 +684,7 @@ public Map<K, ValueDifference<V>> entriesDiffering() {
 
     @Pure
     @Override
-    public boolean equals(@Nullable Object object) {
+    public boolean equals(@CheckForNull Object object) {
       if (object == this) {
         return true;
       }
@@ -637,32 +726,36 @@ public String toString() {
     }
   }
 
-  static class ValueDifferenceImpl<V> implements MapDifference.ValueDifference<V> {
-    private final @Nullable V left;
-    private final @Nullable V right;
+  static class ValueDifferenceImpl<V extends @Nullable Object>
+      implements MapDifference.ValueDifference<V> {
+    @ParametricNullness private final V left;
+    @ParametricNullness private final V right;
 
-    static <V> ValueDifference<V> create(@Nullable V left, @Nullable V right) {
+    static <V extends @Nullable Object> ValueDifference<V> create(
+        @ParametricNullness V left, @ParametricNullness V right) {
       return new ValueDifferenceImpl<V>(left, right);
     }
 
-    private ValueDifferenceImpl(@Nullable V left, @Nullable V right) {
+    private ValueDifferenceImpl(@ParametricNullness V left, @ParametricNullness V right) {
       this.left = left;
       this.right = right;
     }
 
     @Override
+    @ParametricNullness
     public V leftValue() {
       return left;
     }
 
     @Override
+    @ParametricNullness
     public V rightValue() {
       return right;
     }
 
     @Pure
     @Override
-    public boolean equals(@Nullable Object object) {
+    public boolean equals(@CheckForNull Object object) {
       if (object instanceof MapDifference.ValueDifference) {
         MapDifference.ValueDifference<?> that = (MapDifference.ValueDifference<?>) object;
         return Objects.equal(this.left, that.leftValue())
@@ -684,8 +777,8 @@ public String toString() {
     }
   }
 
-  static class SortedMapDifferenceImpl<K, V> extends MapDifferenceImpl<K, V>
-      implements SortedMapDifference<K, V> {
+  static class SortedMapDifferenceImpl<K extends @Nullable Object, V extends @Nullable Object>
+      extends MapDifferenceImpl<K, V> implements SortedMapDifference<K, V> {
     SortedMapDifferenceImpl(
         SortedMap<K, V> onlyOnLeft,
         SortedMap<K, V> onlyOnRight,
@@ -721,7 +814,8 @@ public SortedMap<K, V> entriesOnlyOnRight() {
    * ugly type-casting in one place.
    */
   @SuppressWarnings("unchecked")
-  static <E> Comparator<? super E> orNaturalOrder(@Nullable Comparator<? super E> comparator) {
+  static <E extends @Nullable Object> Comparator<? super E> orNaturalOrder(
+      @CheckForNull Comparator<? super E> comparator) {
     if (comparator != null) { // can't use ? : because of javac bug 5080917
       return comparator;
     }
@@ -752,7 +846,8 @@ static <E> Comparator<? super E> orNaturalOrder(@Nullable Comparator<? super E>
    *
    * @since 14.0
    */
-  public static <K, V> Map<K, V> asMap(Set<K> set, Function<? super K, V> function) {
+  public static <K extends @Nullable Object, V extends @Nullable Object> Map<K, V> asMap(
+      Set<K> set, Function<? super K, V> function) {
     return new AsMapView<>(set, function);
   }
 
@@ -779,7 +874,8 @@ public static <K, V> Map<K, V> asMap(Set<K> set, Function<? super K, V> function
    *
    * @since 14.0
    */
-  public static <K, V> SortedMap<K, V> asMap(SortedSet<K> set, Function<? super K, V> function) {
+  public static <K extends @Nullable Object, V extends @Nullable Object> SortedMap<K, V> asMap(
+      SortedSet<K> set, Function<? super K, V> function) {
     return new SortedAsMapView<>(set, function);
   }
 
@@ -807,12 +903,13 @@ public static <K, V> SortedMap<K, V> asMap(SortedSet<K> set, Function<? super K,
    * @since 14.0
    */
   @GwtIncompatible // NavigableMap
-  public static <K, V> NavigableMap<K, V> asMap(
+  public static <K extends @Nullable Object, V extends @Nullable Object> NavigableMap<K, V> asMap(
       NavigableSet<K> set, Function<? super K, V> function) {
     return new NavigableAsMapView<>(set, function);
   }
 
-  private static class AsMapView<K, V> extends ViewCachingAbstractMap<K, V> {
+  private static class AsMapView<K extends @Nullable Object, V extends @Nullable Object>
+      extends ViewCachingAbstractMap<K, V> {
 
     private final Set<K> set;
     final Function<? super K, V> function;
@@ -842,17 +939,19 @@ public int size() {
     }
 
     @Override
-    public boolean containsKey(@Nullable Object key) {
+    public boolean containsKey(@CheckForNull Object key) {
       return backingSet().contains(key);
     }
 
     @Override
-    public V get(@Nullable Object key) {
+    @CheckForNull
+    public V get(@CheckForNull Object key) {
       return getOrDefault(key, null);
     }
 
     @Override
-    public V getOrDefault(@Nullable Object key, @Nullable V defaultValue) {
+    @CheckForNull
+    public V getOrDefault(@CheckForNull Object key, @CheckForNull V defaultValue) {
       if (Collections2.safeContains(backingSet(), key)) {
         @SuppressWarnings("unchecked") // unsafe, but Javadoc warns about it
         K k = (K) key;
@@ -863,7 +962,8 @@ public V getOrDefault(@Nullable Object key, @Nullable V defaultValue) {
     }
 
     @Override
-    public V remove(@Nullable Object key) {
+    @CheckForNull
+    public V remove(@CheckForNull Object key) {
       if (backingSet().remove(key)) {
         @SuppressWarnings("unchecked") // unsafe, but Javadoc warns about it
         K k = (K) key;
@@ -903,17 +1003,18 @@ public void forEach(BiConsumer<? super K, ? super V> action) {
     }
   }
 
-  static <K, V> Iterator<Entry<K, V>> asMapEntryIterator(
-      Set<K> set, final Function<? super K, V> function) {
+  static <K extends @Nullable Object, V extends @Nullable Object>
+      Iterator<Entry<K, V>> asMapEntryIterator(Set<K> set, final Function<? super K, V> function) {
     return new TransformedIterator<K, Entry<K, V>>(set.iterator()) {
       @Override
-      Entry<K, V> transform(final K key) {
+      Entry<K, V> transform(@ParametricNullness final K key) {
         return immutableEntry(key, function.apply(key));
       }
     };
   }
 
-  private static class SortedAsMapView<K, V> extends AsMapView<K, V> implements SortedMap<K, V> {
+  private static class SortedAsMapView<K extends @Nullable Object, V extends @Nullable Object>
+      extends AsMapView<K, V> implements SortedMap<K, V> {
 
     SortedAsMapView(SortedSet<K> set, Function<? super K, V> function) {
       super(set, function);
@@ -925,6 +1026,7 @@ SortedSet<K> backingSet() {
     }
 
     @Override
+    @CheckForNull
     public Comparator<? super K> comparator() {
       return backingSet().comparator();
     }
@@ -935,33 +1037,37 @@ public Set<K> keySet() {
     }
 
     @Override
-    public SortedMap<K, V> subMap(K fromKey, K toKey) {
+    public SortedMap<K, V> subMap(@ParametricNullness K fromKey, @ParametricNullness K toKey) {
       return asMap(backingSet().subSet(fromKey, toKey), function);
     }
 
     @Override
-    public SortedMap<K, V> headMap(K toKey) {
+    public SortedMap<K, V> headMap(@ParametricNullness K toKey) {
       return asMap(backingSet().headSet(toKey), function);
     }
 
     @Override
-    public SortedMap<K, V> tailMap(K fromKey) {
+    public SortedMap<K, V> tailMap(@ParametricNullness K fromKey) {
       return asMap(backingSet().tailSet(fromKey), function);
     }
 
     @Override
+    @ParametricNullness
     public K firstKey() {
       return backingSet().first();
     }
 
     @Override
+    @ParametricNullness
     public K lastKey() {
       return backingSet().last();
     }
   }
 
   @GwtIncompatible // NavigableMap
-  private static final class NavigableAsMapView<K, V> extends AbstractNavigableMap<K, V> {
+  private static final class NavigableAsMapView<
+          K extends @Nullable Object, V extends @Nullable Object>
+      extends AbstractNavigableMap<K, V> {
     /*
      * Using AbstractNavigableMap is simpler than extending SortedAsMapView and rewriting all the
      * NavigableMap methods.
@@ -977,32 +1083,38 @@ private static final class NavigableAsMapView<K, V> extends AbstractNavigableMap
 
     @Override
     public NavigableMap<K, V> subMap(
-        K fromKey, boolean fromInclusive, K toKey, boolean toInclusive) {
+        @ParametricNullness K fromKey,
+        boolean fromInclusive,
+        @ParametricNullness K toKey,
+        boolean toInclusive) {
       return asMap(set.subSet(fromKey, fromInclusive, toKey, toInclusive), function);
     }
 
     @Override
-    public NavigableMap<K, V> headMap(K toKey, boolean inclusive) {
+    public NavigableMap<K, V> headMap(@ParametricNullness K toKey, boolean inclusive) {
       return asMap(set.headSet(toKey, inclusive), function);
     }
 
     @Override
-    public NavigableMap<K, V> tailMap(K fromKey, boolean inclusive) {
+    public NavigableMap<K, V> tailMap(@ParametricNullness K fromKey, boolean inclusive) {
       return asMap(set.tailSet(fromKey, inclusive), function);
     }
 
     @Override
+    @CheckForNull
     public Comparator<? super K> comparator() {
       return set.comparator();
     }
 
     @Override
-    public @Nullable V get(@Nullable Object key) {
+    @CheckForNull
+    public V get(@CheckForNull Object key) {
       return getOrDefault(key, null);
     }
 
     @Override
-    public @Nullable V getOrDefault(@Nullable Object key, @Nullable V defaultValue) {
+    @CheckForNull
+    public V getOrDefault(@CheckForNull Object key, @CheckForNull V defaultValue) {
       if (Collections2.safeContains(set, key)) {
         @SuppressWarnings("unchecked") // unsafe, but Javadoc warns about it
         K k = (K) key;
@@ -1053,7 +1165,7 @@ public NavigableMap<K, V> descendingMap() {
     }
   }
 
-  private static <E> Set<E> removeOnlySet(final Set<E> set) {
+  private static <E extends @Nullable Object> Set<E> removeOnlySet(final Set<E> set) {
     return new ForwardingSet<E>() {
       @Override
       protected Set<E> delegate() {
@@ -1061,7 +1173,7 @@ protected Set<E> delegate() {
       }
 
       @Override
-      public boolean add(E element) {
+      public boolean add(@ParametricNullness E element) {
         throw new UnsupportedOperationException();
       }
 
@@ -1072,7 +1184,8 @@ public boolean addAll(Collection<? extends E> es) {
     };
   }
 
-  private static <E> SortedSet<E> removeOnlySortedSet(final SortedSet<E> set) {
+  private static <E extends @Nullable Object> SortedSet<E> removeOnlySortedSet(
+      final SortedSet<E> set) {
     return new ForwardingSortedSet<E>() {
       @Override
       protected SortedSet<E> delegate() {
@@ -1080,7 +1193,7 @@ protected SortedSet<E> delegate() {
       }
 
       @Override
-      public boolean add(E element) {
+      public boolean add(@ParametricNullness E element) {
         throw new UnsupportedOperationException();
       }
 
@@ -1090,24 +1203,26 @@ public boolean addAll(Collection<? extends E> es) {
       }
 
       @Override
-      public SortedSet<E> headSet(E toElement) {
+      public SortedSet<E> headSet(@ParametricNullness E toElement) {
         return removeOnlySortedSet(super.headSet(toElement));
       }
 
       @Override
-      public SortedSet<E> subSet(E fromElement, E toElement) {
+      public SortedSet<E> subSet(
+          @ParametricNullness E fromElement, @ParametricNullness E toElement) {
         return removeOnlySortedSet(super.subSet(fromElement, toElement));
       }
 
       @Override
-      public SortedSet<E> tailSet(E fromElement) {
+      public SortedSet<E> tailSet(@ParametricNullness E fromElement) {
         return removeOnlySortedSet(super.tailSet(fromElement));
       }
     };
   }
 
   @GwtIncompatible // NavigableSet
-  private static <E> NavigableSet<E> removeOnlyNavigableSet(final NavigableSet<E> set) {
+  private static <E extends @Nullable Object> NavigableSet<E> removeOnlyNavigableSet(
+      final NavigableSet<E> set) {
     return new ForwardingNavigableSet<E>() {
       @Override
       protected NavigableSet<E> delegate() {
@@ -1115,7 +1230,7 @@ protected NavigableSet<E> delegate() {
       }
 
       @Override
-      public boolean add(E element) {
+      public boolean add(@ParametricNullness E element) {
         throw new UnsupportedOperationException();
       }
 
@@ -1125,34 +1240,38 @@ public boolean addAll(Collection<? extends E> es) {
       }
 
       @Override
-      public SortedSet<E> headSet(E toElement) {
+      public SortedSet<E> headSet(@ParametricNullness E toElement) {
         return removeOnlySortedSet(super.headSet(toElement));
       }
 
       @Override
-      public NavigableSet<E> headSet(E toElement, boolean inclusive) {
+      public NavigableSet<E> headSet(@ParametricNullness E toElement, boolean inclusive) {
         return removeOnlyNavigableSet(super.headSet(toElement, inclusive));
       }
 
       @Override
-      public SortedSet<E> subSet(E fromElement, E toElement) {
+      public SortedSet<E> subSet(
+          @ParametricNullness E fromElement, @ParametricNullness E toElement) {
         return removeOnlySortedSet(super.subSet(fromElement, toElement));
       }
 
       @Override
       public NavigableSet<E> subSet(
-          E fromElement, boolean fromInclusive, E toElement, boolean toInclusive) {
+          @ParametricNullness E fromElement,
+          boolean fromInclusive,
+          @ParametricNullness E toElement,
+          boolean toInclusive) {
         return removeOnlyNavigableSet(
             super.subSet(fromElement, fromInclusive, toElement, toInclusive));
       }
 
       @Override
-      public SortedSet<E> tailSet(E fromElement) {
+      public SortedSet<E> tailSet(@ParametricNullness E fromElement) {
         return removeOnlySortedSet(super.tailSet(fromElement));
       }
 
       @Override
-      public NavigableSet<E> tailSet(E fromElement, boolean inclusive) {
+      public NavigableSet<E> tailSet(@ParametricNullness E fromElement, boolean inclusive) {
         return removeOnlyNavigableSet(super.tailSet(fromElement, inclusive));
       }
 
@@ -1200,13 +1319,13 @@ public static <K, V> ImmutableMap<K, V> toMap(
   public static <K, V> ImmutableMap<K, V> toMap(
       Iterator<K> keys, Function<? super K, V> valueFunction) {
     checkNotNull(valueFunction);
-    // Using LHM instead of a builder so as not to fail on duplicate keys
-    Map<K, V> builder = newLinkedHashMap();
+    ImmutableMap.Builder<K, V> builder = ImmutableMap.builder();
     while (keys.hasNext()) {
       K key = keys.next();
       builder.put(key, valueFunction.apply(key));
     }
-    return ImmutableMap.copyOf(builder);
+    // Using buildKeepingLast() so as not to fail on duplicate keys
+    return builder.buildKeepingLast();
   }
 
   /**
@@ -1283,7 +1402,7 @@ public static <K, V> ImmutableMap<K, V> uniqueIndex(
       builder.put(keyFunction.apply(value), value);
     }
     try {
-      return builder.build();
+      return builder.buildOrThrow();
     } catch (IllegalArgumentException duplicateKeys) {
       throw new IllegalArgumentException(
           duplicateKeys.getMessage()
@@ -1298,19 +1417,45 @@ public static <K, V> ImmutableMap<K, V> uniqueIndex(
    *
    * @param properties a {@code Properties} object to be converted
    * @return an immutable map containing all the entries in {@code properties}
-   * @throws ClassCastException if any key in {@code Properties} is not a {@code String}
-   * @throws NullPointerException if any key or value in {@code Properties} is null
+   * @throws ClassCastException if any key in {@code properties} is not a {@code String}
+   * @throws NullPointerException if any key or value in {@code properties} is null
    */
   @GwtIncompatible // java.util.Properties
   public static ImmutableMap<String, String> fromProperties(Properties properties) {
     ImmutableMap.Builder<String, String> builder = ImmutableMap.builder();
 
     for (Enumeration<?> e = properties.propertyNames(); e.hasMoreElements(); ) {
-      String key = (String) e.nextElement();
-      builder.put(key, properties.getProperty(key));
-    }
-
-    return builder.build();
+      /*
+       * requireNonNull is safe because propertyNames contains only non-null elements.
+       *
+       * Accordingly, we have it annotated as returning `Enumeration<? extends Object>` in our
+       * prototype checker's JDK. However, the checker still sees the return type as plain
+       * `Enumeration<?>`, probably because of one of the following two bugs (and maybe those two
+       * bugs are themselves just symptoms of the same underlying problem):
+       *
+       * https://github.com/typetools/checker-framework/issues/3030
+       *
+       * https://github.com/typetools/checker-framework/issues/3236
+       */
+      String key = (String) requireNonNull(e.nextElement());
+      /*
+       * requireNonNull is safe because the key came from propertyNames...
+       *
+       * ...except that it's possible for users to insert a string key with a non-string value, and
+       * in that case, getProperty *will* return null.
+       *
+       * TODO(b/192002623): Handle that case: Either:
+       *
+       * - Skip non-string keys and values entirely, as proposed in the linked bug.
+       *
+       * - Throw ClassCastException instead of NullPointerException, as documented in the current
+       *   Javadoc. (Note that we can't necessarily "just" change our call to `getProperty` to `get`
+       *   because `get` does not consult the default properties.)
+       */
+      builder.put(key, requireNonNull(properties.getProperty(key)));
+    }
+
+    return builder.buildOrThrow();
   }
 
   /**
@@ -1326,7 +1471,8 @@ public static ImmutableMap<String, String> fromProperties(Properties properties)
    * @param value the value to be associated with the returned entry
    */
   @GwtCompatible(serializable = true)
-  public static <K, V> Entry<K, V> immutableEntry(@Nullable K key, @Nullable V value) {
+  public static <K extends @Nullable Object, V extends @Nullable Object> Entry<K, V> immutableEntry(
+      @ParametricNullness K key, @ParametricNullness V value) {
     return new ImmutableEntry<>(key, value);
   }
 
@@ -1338,7 +1484,8 @@ public static <K, V> Entry<K, V> immutableEntry(@Nullable K key, @Nullable V val
    * @param entrySet the entries for which to return an unmodifiable view
    * @return an unmodifiable view of the entries
    */
-  static <K, V> Set<Entry<K, V>> unmodifiableEntrySet(Set<Entry<K, V>> entrySet) {
+  static <K extends @Nullable Object, V extends @Nullable Object>
+      Set<Entry<K, V>> unmodifiableEntrySet(Set<Entry<K, V>> entrySet) {
     return new UnmodifiableEntrySet<>(Collections.unmodifiableSet(entrySet));
   }
 
@@ -1351,23 +1498,27 @@ static <K, V> Set<Entry<K, V>> unmodifiableEntrySet(Set<Entry<K, V>> entrySet) {
    * @param entry the entry for which to return an unmodifiable view
    * @return an unmodifiable view of the entry
    */
-  static <K, V> Entry<K, V> unmodifiableEntry(final Entry<? extends K, ? extends V> entry) {
+  static <K extends @Nullable Object, V extends @Nullable Object> Entry<K, V> unmodifiableEntry(
+      final Entry<? extends K, ? extends V> entry) {
     checkNotNull(entry);
     return new AbstractMapEntry<K, V>() {
       @Override
+      @ParametricNullness
       public K getKey() {
         return entry.getKey();
       }
 
       @Override
+      @ParametricNullness
       public V getValue() {
         return entry.getValue();
       }
     };
   }
 
-  static <K, V> UnmodifiableIterator<Entry<K, V>> unmodifiableEntryIterator(
-      final Iterator<Entry<K, V>> entryIterator) {
+  static <K extends @Nullable Object, V extends @Nullable Object>
+      UnmodifiableIterator<Entry<K, V>> unmodifiableEntryIterator(
+          final Iterator<Entry<K, V>> entryIterator) {
     return new UnmodifiableIterator<Entry<K, V>>() {
       @Override
       public boolean hasNext() {
@@ -1382,7 +1533,8 @@ public Entry<K, V> next() {
   }
 
   /** @see Multimaps#unmodifiableEntries */
-  static class UnmodifiableEntries<K, V> extends ForwardingCollection<Entry<K, V>> {
+  static class UnmodifiableEntries<K extends @Nullable Object, V extends @Nullable Object>
+      extends ForwardingCollection<Entry<K, V>> {
     private final Collection<Entry<K, V>> entries;
 
     UnmodifiableEntries(Collection<Entry<K, V>> entries) {
@@ -1403,11 +1555,19 @@ public Iterator<Entry<K, V>> iterator() {
 
     @Override
     public Object[] toArray() {
-      return standardToArray();
+      /*
+       * standardToArray returns `@Nullable Object[]` rather than `Object[]` but only because it can
+       * be used with collections that may contain null. This collection never contains nulls, so we
+       * can treat it as a plain `Object[]`.
+       */
+      @SuppressWarnings("nullness")
+      Object[] result = standardToArray();
+      return result;
     }
 
     @Override
-    public <T> T[] toArray(T[] array) {
+    @SuppressWarnings("nullness") // b/192354773 in our checker affects toArray declarations
+    public <T extends @Nullable Object> T[] toArray(T[] array) {
       return standardToArray(array);
     }
 
@@ -1421,8 +1581,8 @@ public <T> T[] toArray(T[] array) {
   }
 
   /** @see Maps#unmodifiableEntrySet(Set) */
-  static class UnmodifiableEntrySet<K, V> extends UnmodifiableEntries<K, V>
-      implements Set<Entry<K, V>> {
+  static class UnmodifiableEntrySet<K extends @Nullable Object, V extends @Nullable Object>
+      extends UnmodifiableEntries<K, V> implements Set<Entry<K, V>> {
     UnmodifiableEntrySet(Set<Entry<K, V>> entries) {
       super(entries);
     }
@@ -1431,7 +1591,7 @@ static class UnmodifiableEntrySet<K, V> extends UnmodifiableEntries<K, V>
 
     @Pure
     @Override
-    public boolean equals(@Nullable Object object) {
+    public boolean equals(@CheckForNull Object object) {
       return Sets.equalsImpl(this, object);
     }
 
@@ -1480,7 +1640,7 @@ private static <X, Y> Y convert(BiMap<X, Y> bimap, X input) {
     }
 
     @Override
-    public boolean equals(@Nullable Object object) {
+    public boolean equals(@CheckForNull Object object) {
       if (object instanceof BiMapConverter) {
         BiMapConverter<?, ?> that = (BiMapConverter<?, ?>) object;
         return this.bimap.equals(that.bimap);
@@ -1531,7 +1691,8 @@ public String toString() {
    * @param bimap the bimap to be wrapped in a synchronized view
    * @return a synchronized view of the specified bimap
    */
-  public static <K, V> BiMap<K, V> synchronizedBiMap(BiMap<K, V> bimap) {
+  public static <K extends @Nullable Object, V extends @Nullable Object>
+      BiMap<K, V> synchronizedBiMap(BiMap<K, V> bimap) {
     return Synchronized.biMap(bimap, null);
   }
 
@@ -1546,19 +1707,20 @@ public static <K, V> BiMap<K, V> synchronizedBiMap(BiMap<K, V> bimap) {
    * @param bimap the bimap for which an unmodifiable view is to be returned
    * @return an unmodifiable view of the specified bimap
    */
-  public static <K, V> BiMap<K, V> unmodifiableBiMap(BiMap<? extends K, ? extends V> bimap) {
+  public static <K extends @Nullable Object, V extends @Nullable Object>
+      BiMap<K, V> unmodifiableBiMap(BiMap<? extends K, ? extends V> bimap) {
     return new UnmodifiableBiMap<>(bimap, null);
   }
 
   /** @see Maps#unmodifiableBiMap(BiMap) */
-  private static class UnmodifiableBiMap<K, V> extends ForwardingMap<K, V>
-      implements BiMap<K, V>, Serializable {
+  private static class UnmodifiableBiMap<K extends @Nullable Object, V extends @Nullable Object>
+      extends ForwardingMap<K, V> implements BiMap<K, V>, Serializable {
     final Map<K, V> unmodifiableMap;
     final BiMap<? extends K, ? extends V> delegate;
-    @RetainedWith @Nullable BiMap<V, K> inverse;
-    transient @Nullable Set<V> values;
+    @RetainedWith @CheckForNull BiMap<V, K> inverse;
+    @CheckForNull transient Set<V> values;
 
-    UnmodifiableBiMap(BiMap<? extends K, ? extends V> delegate, @Nullable BiMap<V, K> inverse) {
+    UnmodifiableBiMap(BiMap<? extends K, ? extends V> delegate, @CheckForNull BiMap<V, K> inverse) {
       unmodifiableMap = Collections.unmodifiableMap(delegate);
       this.delegate = delegate;
       this.inverse = inverse;
@@ -1570,7 +1732,59 @@ protected Map<K, V> delegate() {
     }
 
     @Override
-    public V forcePut(K key, V value) {
+    @CheckForNull
+    public V forcePut(@ParametricNullness K key, @ParametricNullness V value) {
+      throw new UnsupportedOperationException();
+    }
+
+    @Override
+    public void replaceAll(BiFunction<? super K, ? super V, ? extends V> function) {
+      throw new UnsupportedOperationException();
+    }
+
+    @Override
+    @CheckForNull
+    public V putIfAbsent(K key, V value) {
+      throw new UnsupportedOperationException();
+    }
+
+    @Override
+    public boolean remove(@Nullable Object key, @Nullable Object value) {
+      throw new UnsupportedOperationException();
+    }
+
+    @Override
+    public boolean replace(K key, V oldValue, V newValue) {
+      throw new UnsupportedOperationException();
+    }
+
+    @Override
+    @CheckForNull
+    public V replace(K key, V value) {
+      throw new UnsupportedOperationException();
+    }
+
+    @Override
+    public V computeIfAbsent(
+        K key, java.util.function.Function<? super K, ? extends V> mappingFunction) {
+      throw new UnsupportedOperationException();
+    }
+
+    @Override
+    public V computeIfPresent(
+        K key, BiFunction<? super K, ? super V, ? extends V> remappingFunction) {
+      throw new UnsupportedOperationException();
+    }
+
+    @Override
+    public V compute(
+        K key, BiFunction<? super K, ? super @Nullable V, ? extends V> remappingFunction) {
+      throw new UnsupportedOperationException();
+    }
+
+    @Override
+    public V merge(
+        K key, V value, BiFunction<? super V, ? super V, ? extends V> remappingFunction) {
       throw new UnsupportedOperationException();
     }
 
@@ -1625,8 +1839,9 @@ public Set<V> values() {
    * function} should be fast. To avoid lazy evaluation when the returned map doesn't need to be a
    * view, copy the returned map into a new map of your choosing.
    */
-  public static <K, V1, V2> Map<K, V2> transformValues(
-      Map<K, V1> fromMap, Function<? super V1, V2> function) {
+  public static <
+          K extends @Nullable Object, V1 extends @Nullable Object, V2 extends @Nullable Object>
+      Map<K, V2> transformValues(Map<K, V1> fromMap, Function<? super V1, V2> function) {
     return transformEntries(fromMap, asEntryTransformer(function));
   }
 
@@ -1666,8 +1881,10 @@ public static <K, V1, V2> Map<K, V2> transformValues(
    *
    * @since 11.0
    */
-  public static <K, V1, V2> SortedMap<K, V2> transformValues(
-      SortedMap<K, V1> fromMap, Function<? super V1, V2> function) {
+  public static <
+          K extends @Nullable Object, V1 extends @Nullable Object, V2 extends @Nullable Object>
+      SortedMap<K, V2> transformValues(
+          SortedMap<K, V1> fromMap, Function<? super V1, V2> function) {
     return transformEntries(fromMap, asEntryTransformer(function));
   }
 
@@ -1710,8 +1927,10 @@ public static <K, V1, V2> SortedMap<K, V2> transformValues(
    * @since 13.0
    */
   @GwtIncompatible // NavigableMap
-  public static <K, V1, V2> NavigableMap<K, V2> transformValues(
-      NavigableMap<K, V1> fromMap, Function<? super V1, V2> function) {
+  public static <
+          K extends @Nullable Object, V1 extends @Nullable Object, V2 extends @Nullable Object>
+      NavigableMap<K, V2> transformValues(
+          NavigableMap<K, V1> fromMap, Function<? super V1, V2> function) {
     return transformEntries(fromMap, asEntryTransformer(function));
   }
 
@@ -1762,8 +1981,10 @@ public static <K, V1, V2> NavigableMap<K, V2> transformValues(
    *
    * @since 7.0
    */
-  public static <K, V1, V2> Map<K, V2> transformEntries(
-      Map<K, V1> fromMap, EntryTransformer<? super K, ? super V1, V2> transformer) {
+  public static <
+          K extends @Nullable Object, V1 extends @Nullable Object, V2 extends @Nullable Object>
+      Map<K, V2> transformEntries(
+          Map<K, V1> fromMap, EntryTransformer<? super K, ? super V1, V2> transformer) {
     return new TransformedEntriesMap<>(fromMap, transformer);
   }
 
@@ -1814,8 +2035,10 @@ public static <K, V1, V2> Map<K, V2> transformEntries(
    *
    * @since 11.0
    */
-  public static <K, V1, V2> SortedMap<K, V2> transformEntries(
-      SortedMap<K, V1> fromMap, EntryTransformer<? super K, ? super V1, V2> transformer) {
+  public static <
+          K extends @Nullable Object, V1 extends @Nullable Object, V2 extends @Nullable Object>
+      SortedMap<K, V2> transformEntries(
+          SortedMap<K, V1> fromMap, EntryTransformer<? super K, ? super V1, V2> transformer) {
     return new TransformedEntriesSortedMap<>(fromMap, transformer);
   }
 
@@ -1868,8 +2091,10 @@ public static <K, V1, V2> SortedMap<K, V2> transformEntries(
    * @since 13.0
    */
   @GwtIncompatible // NavigableMap
-  public static <K, V1, V2> NavigableMap<K, V2> transformEntries(
-      final NavigableMap<K, V1> fromMap, EntryTransformer<? super K, ? super V1, V2> transformer) {
+  public static <
+          K extends @Nullable Object, V1 extends @Nullable Object, V2 extends @Nullable Object>
+      NavigableMap<K, V2> transformEntries(
+          NavigableMap<K, V1> fromMap, EntryTransformer<? super K, ? super V1, V2> transformer) {
     return new TransformedEntriesNavigableMap<>(fromMap, transformer);
   }
 
@@ -1883,7 +2108,8 @@ public static <K, V1, V2> NavigableMap<K, V2> transformEntries(
    * @since 7.0
    */
   @FunctionalInterface
-  public interface EntryTransformer<K, V1, V2> {
+  public interface EntryTransformer<
+      K extends @Nullable Object, V1 extends @Nullable Object, V2 extends @Nullable Object> {
     /**
      * Determines an output value based on a key-value pair. This method is <i>generally
      * expected</i>, but not absolutely required, to have the following properties:
@@ -1898,38 +2124,43 @@ public interface EntryTransformer<K, V1, V2> {
      * @throws NullPointerException if the key or value is null and this transformer does not accept
      *     null arguments
      */
-    V2 transformEntry(@Nullable K key, @Nullable V1 value);
+    V2 transformEntry(@ParametricNullness K key, @ParametricNullness V1 value);
   }
 
   /** Views a function as an entry transformer that ignores the entry key. */
-  static <K, V1, V2> EntryTransformer<K, V1, V2> asEntryTransformer(
-      final Function<? super V1, V2> function) {
+  static <K extends @Nullable Object, V1 extends @Nullable Object, V2 extends @Nullable Object>
+      EntryTransformer<K, V1, V2> asEntryTransformer(final Function<? super V1, V2> function) {
     checkNotNull(function);
     return new EntryTransformer<K, V1, V2>() {
       @Override
-      public V2 transformEntry(K key, V1 value) {
+      @ParametricNullness
+      public V2 transformEntry(@ParametricNullness K key, @ParametricNullness V1 value) {
         return function.apply(value);
       }
     };
   }
 
-  static <K, V1, V2> Function<V1, V2> asValueToValueFunction(
-      final EntryTransformer<? super K, V1, V2> transformer, final K key) {
+  static <K extends @Nullable Object, V1 extends @Nullable Object, V2 extends @Nullable Object>
+      Function<V1, V2> asValueToValueFunction(
+          final EntryTransformer<? super K, V1, V2> transformer, @ParametricNullness final K key) {
     checkNotNull(transformer);
     return new Function<V1, V2>() {
       @Override
-      public V2 apply(@Nullable V1 v1) {
+      @ParametricNullness
+      public V2 apply(@ParametricNullness V1 v1) {
         return transformer.transformEntry(key, v1);
       }
     };
   }
 
   /** Views an entry transformer as a function from {@code Entry} to values. */
-  static <K, V1, V2> Function<Entry<K, V1>, V2> asEntryToValueFunction(
-      final EntryTransformer<? super K, ? super V1, V2> transformer) {
+  static <K extends @Nullable Object, V1 extends @Nullable Object, V2 extends @Nullable Object>
+      Function<Entry<K, V1>, V2> asEntryToValueFunction(
+          final EntryTransformer<? super K, ? super V1, V2> transformer) {
     checkNotNull(transformer);
     return new Function<Entry<K, V1>, V2>() {
       @Override
+      @ParametricNullness
       public V2 apply(Entry<K, V1> entry) {
         return transformer.transformEntry(entry.getKey(), entry.getValue());
       }
@@ -1937,17 +2168,20 @@ public V2 apply(Entry<K, V1> entry) {
   }
 
   /** Returns a view of an entry transformed by the specified transformer. */
-  static <V2, K, V1> Entry<K, V2> transformEntry(
-      final EntryTransformer<? super K, ? super V1, V2> transformer, final Entry<K, V1> entry) {
+  static <V2 extends @Nullable Object, K extends @Nullable Object, V1 extends @Nullable Object>
+      Entry<K, V2> transformEntry(
+          final EntryTransformer<? super K, ? super V1, V2> transformer, final Entry<K, V1> entry) {
     checkNotNull(transformer);
     checkNotNull(entry);
     return new AbstractMapEntry<K, V2>() {
       @Override
+      @ParametricNullness
       public K getKey() {
         return entry.getKey();
       }
 
       @Override
+      @ParametricNullness
       public V2 getValue() {
         return transformer.transformEntry(entry.getKey(), entry.getValue());
       }
@@ -1955,8 +2189,9 @@ public V2 getValue() {
   }
 
   /** Views an entry transformer as a function from entries to entries. */
-  static <K, V1, V2> Function<Entry<K, V1>, Entry<K, V2>> asEntryToEntryFunction(
-      final EntryTransformer<? super K, ? super V1, V2> transformer) {
+  static <K extends @Nullable Object, V1 extends @Nullable Object, V2 extends @Nullable Object>
+      Function<Entry<K, V1>, Entry<K, V2>> asEntryToEntryFunction(
+          final EntryTransformer<? super K, ? super V1, V2> transformer) {
     checkNotNull(transformer);
     return new Function<Entry<K, V1>, Entry<K, V2>>() {
       @Override
@@ -1966,7 +2201,9 @@ public Entry<K, V2> apply(final Entry<K, V1> entry) {
     };
   }
 
-  static class TransformedEntriesMap<K, V1, V2> extends IteratorBasedAbstractMap<K, V2> {
+  static class TransformedEntriesMap<
+          K extends @Nullable Object, V1 extends @Nullable Object, V2 extends @Nullable Object>
+      extends IteratorBasedAbstractMap<K, V2> {
     final Map<K, V1> fromMap;
     final EntryTransformer<? super K, ? super V1, V2> transformer;
 
@@ -1982,31 +2219,37 @@ public int size() {
     }
 
     @Override
-    public boolean containsKey(Object key) {
+    public boolean containsKey(@CheckForNull Object key) {
       return fromMap.containsKey(key);
     }
 
     @Override
-    public @Nullable V2 get(@Nullable Object key) {
+    @CheckForNull
+    public V2 get(@CheckForNull Object key) {
       return getOrDefault(key, null);
     }
 
     // safe as long as the user followed the <b>Warning</b> in the javadoc
     @SuppressWarnings("unchecked")
     @Override
-    public @Nullable V2 getOrDefault(@Nullable Object key, @Nullable V2 defaultValue) {
+    @CheckForNull
+    public V2 getOrDefault(@CheckForNull Object key, @CheckForNull V2 defaultValue) {
       V1 value = fromMap.get(key);
-      return (value != null || fromMap.containsKey(key))
-          ? transformer.transformEntry((K) key, value)
-          : defaultValue;
+      if (value != null || fromMap.containsKey(key)) {
+        // The cast is safe because of the containsKey check.
+        return transformer.transformEntry((K) key, uncheckedCastNullableTToT(value));
+      }
+      return defaultValue;
     }
 
     // safe as long as the user followed the <b>Warning</b> in the javadoc
     @SuppressWarnings("unchecked")
     @Override
-    public V2 remove(Object key) {
+    @CheckForNull
+    public V2 remove(@CheckForNull Object key) {
       return fromMap.containsKey(key)
-          ? transformer.transformEntry((K) key, fromMap.remove(key))
+          // The cast is safe because of the containsKey check.
+          ? transformer.transformEntry((K) key, uncheckedCastNullableTToT(fromMap.remove(key)))
           : null;
     }
 
@@ -2045,8 +2288,9 @@ public Collection<V2> values() {
     }
   }
 
-  static class TransformedEntriesSortedMap<K, V1, V2> extends TransformedEntriesMap<K, V1, V2>
-      implements SortedMap<K, V2> {
+  static class TransformedEntriesSortedMap<
+          K extends @Nullable Object, V1 extends @Nullable Object, V2 extends @Nullable Object>
+      extends TransformedEntriesMap<K, V1, V2> implements SortedMap<K, V2> {
 
     protected SortedMap<K, V1> fromMap() {
       return (SortedMap<K, V1>) fromMap;
@@ -2058,38 +2302,42 @@ protected SortedMap<K, V1> fromMap() {
     }
 
     @Override
+    @CheckForNull
     public Comparator<? super K> comparator() {
       return fromMap().comparator();
     }
 
     @Override
+    @ParametricNullness
     public K firstKey() {
       return fromMap().firstKey();
     }
 
     @Override
-    public SortedMap<K, V2> headMap(K toKey) {
+    public SortedMap<K, V2> headMap(@ParametricNullness K toKey) {
       return transformEntries(fromMap().headMap(toKey), transformer);
     }
 
     @Override
+    @ParametricNullness
     public K lastKey() {
       return fromMap().lastKey();
     }
 
     @Override
-    public SortedMap<K, V2> subMap(K fromKey, K toKey) {
+    public SortedMap<K, V2> subMap(@ParametricNullness K fromKey, @ParametricNullness K toKey) {
       return transformEntries(fromMap().subMap(fromKey, toKey), transformer);
     }
 
     @Override
-    public SortedMap<K, V2> tailMap(K fromKey) {
+    public SortedMap<K, V2> tailMap(@ParametricNullness K fromKey) {
       return transformEntries(fromMap().tailMap(fromKey), transformer);
     }
   }
 
   @GwtIncompatible // NavigableMap
-  private static class TransformedEntriesNavigableMap<K, V1, V2>
+  private static class TransformedEntriesNavigableMap<
+          K extends @Nullable Object, V1 extends @Nullable Object, V2 extends @Nullable Object>
       extends TransformedEntriesSortedMap<K, V1, V2> implements NavigableMap<K, V2> {
 
     TransformedEntriesNavigableMap(
@@ -2098,12 +2346,14 @@ private static class TransformedEntriesNavigableMap<K, V1, V2>
     }
 
     @Override
-    public Entry<K, V2> ceilingEntry(K key) {
+    @CheckForNull
+    public Entry<K, V2> ceilingEntry(@ParametricNullness K key) {
       return transformEntry(fromMap().ceilingEntry(key));
     }
 
     @Override
-    public K ceilingKey(K key) {
+    @CheckForNull
+    public K ceilingKey(@ParametricNullness K key) {
       return fromMap().ceilingKey(key);
     }
 
@@ -2118,52 +2368,60 @@ public NavigableMap<K, V2> descendingMap() {
     }
 
     @Override
+    @CheckForNull
     public Entry<K, V2> firstEntry() {
       return transformEntry(fromMap().firstEntry());
     }
 
     @Override
-    public Entry<K, V2> floorEntry(K key) {
+    @CheckForNull
+    public Entry<K, V2> floorEntry(@ParametricNullness K key) {
       return transformEntry(fromMap().floorEntry(key));
     }
 
     @Override
-    public K floorKey(K key) {
+    @CheckForNull
+    public K floorKey(@ParametricNullness K key) {
       return fromMap().floorKey(key);
     }
 
     @Override
-    public NavigableMap<K, V2> headMap(K toKey) {
+    public NavigableMap<K, V2> headMap(@ParametricNullness K toKey) {
       return headMap(toKey, false);
     }
 
     @Override
-    public NavigableMap<K, V2> headMap(K toKey, boolean inclusive) {
+    public NavigableMap<K, V2> headMap(@ParametricNullness K toKey, boolean inclusive) {
       return transformEntries(fromMap().headMap(toKey, inclusive), transformer);
     }
 
     @Override
-    public Entry<K, V2> higherEntry(K key) {
+    @CheckForNull
+    public Entry<K, V2> higherEntry(@ParametricNullness K key) {
       return transformEntry(fromMap().higherEntry(key));
     }
 
     @Override
-    public K higherKey(K key) {
+    @CheckForNull
+    public K higherKey(@ParametricNullness K key) {
       return fromMap().higherKey(key);
     }
 
     @Override
+    @CheckForNull
     public Entry<K, V2> lastEntry() {
       return transformEntry(fromMap().lastEntry());
     }
 
     @Override
-    public Entry<K, V2> lowerEntry(K key) {
+    @CheckForNull
+    public Entry<K, V2> lowerEntry(@ParametricNullness K key) {
       return transformEntry(fromMap().lowerEntry(key));
     }
 
     @Override
-    public K lowerKey(K key) {
+    @CheckForNull
+    public K lowerKey(@ParametricNullness K key) {
       return fromMap().lowerKey(key);
     }
 
@@ -2173,38 +2431,44 @@ public NavigableSet<K> navigableKeySet() {
     }
 
     @Override
+    @CheckForNull
     public Entry<K, V2> pollFirstEntry() {
       return transformEntry(fromMap().pollFirstEntry());
     }
 
     @Override
+    @CheckForNull
     public Entry<K, V2> pollLastEntry() {
       return transformEntry(fromMap().pollLastEntry());
     }
 
     @Override
     public NavigableMap<K, V2> subMap(
-        K fromKey, boolean fromInclusive, K toKey, boolean toInclusive) {
+        @ParametricNullness K fromKey,
+        boolean fromInclusive,
+        @ParametricNullness K toKey,
+        boolean toInclusive) {
       return transformEntries(
           fromMap().subMap(fromKey, fromInclusive, toKey, toInclusive), transformer);
     }
 
     @Override
-    public NavigableMap<K, V2> subMap(K fromKey, K toKey) {
+    public NavigableMap<K, V2> subMap(@ParametricNullness K fromKey, @ParametricNullness K toKey) {
       return subMap(fromKey, true, toKey, false);
     }
 
     @Override
-    public NavigableMap<K, V2> tailMap(K fromKey) {
+    public NavigableMap<K, V2> tailMap(@ParametricNullness K fromKey) {
       return tailMap(fromKey, true);
     }
 
     @Override
-    public NavigableMap<K, V2> tailMap(K fromKey, boolean inclusive) {
+    public NavigableMap<K, V2> tailMap(@ParametricNullness K fromKey, boolean inclusive) {
       return transformEntries(fromMap().tailMap(fromKey, inclusive), transformer);
     }
 
-    private @Nullable Entry<K, V2> transformEntry(@Nullable Entry<K, V1> entry) {
+    @CheckForNull
+    private Entry<K, V2> transformEntry(@CheckForNull Entry<K, V1> entry) {
       return (entry == null) ? null : Maps.transformEntry(transformer, entry);
     }
 
@@ -2214,11 +2478,13 @@ protected NavigableMap<K, V1> fromMap() {
     }
   }
 
-  static <K> Predicate<Entry<K, ?>> keyPredicateOnEntries(Predicate<? super K> keyPredicate) {
+  static <K extends @Nullable Object> Predicate<Entry<K, ?>> keyPredicateOnEntries(
+      Predicate<? super K> keyPredicate) {
     return compose(keyPredicate, Maps.<K>keyFunction());
   }
 
-  static <V> Predicate<Entry<?, V>> valuePredicateOnEntries(Predicate<? super V> valuePredicate) {
+  static <V extends @Nullable Object> Predicate<Entry<?, V>> valuePredicateOnEntries(
+      Predicate<? super V> valuePredicate) {
     return compose(valuePredicate, Maps.<V>valueFunction());
   }
 
@@ -2245,7 +2511,7 @@ static <V> Predicate<Entry<?, V>> valuePredicateOnEntries(Predicate<? super V> v
    * {@link Predicate#apply}. Do not provide a predicate such as {@code
    * Predicates.instanceOf(ArrayList.class)}, which is inconsistent with equals.
    */
-  public static <K, V> Map<K, V> filterKeys(
+  public static <K extends @Nullable Object, V extends @Nullable Object> Map<K, V> filterKeys(
       Map<K, V> unfiltered, final Predicate<? super K> keyPredicate) {
     checkNotNull(keyPredicate);
     Predicate<Entry<K, ?>> entryPredicate = keyPredicateOnEntries(keyPredicate);
@@ -2280,7 +2546,7 @@ public static <K, V> Map<K, V> filterKeys(
    *
    * @since 11.0
    */
-  public static <K, V> SortedMap<K, V> filterKeys(
+  public static <K extends @Nullable Object, V extends @Nullable Object> SortedMap<K, V> filterKeys(
       SortedMap<K, V> unfiltered, final Predicate<? super K> keyPredicate) {
     // TODO(lowasser): Return a subclass of Maps.FilteredKeyMap for slightly better
     // performance.
@@ -2314,8 +2580,9 @@ public static <K, V> SortedMap<K, V> filterKeys(
    * @since 14.0
    */
   @GwtIncompatible // NavigableMap
-  public static <K, V> NavigableMap<K, V> filterKeys(
-      NavigableMap<K, V> unfiltered, final Predicate<? super K> keyPredicate) {
+  public static <K extends @Nullable Object, V extends @Nullable Object>
+      NavigableMap<K, V> filterKeys(
+          NavigableMap<K, V> unfiltered, final Predicate<? super K> keyPredicate) {
     // TODO(lowasser): Return a subclass of Maps.FilteredKeyMap for slightly better
     // performance.
     return filterEntries(unfiltered, Maps.<K>keyPredicateOnEntries(keyPredicate));
@@ -2345,7 +2612,7 @@ public static <K, V> NavigableMap<K, V> filterKeys(
    *
    * @since 14.0
    */
-  public static <K, V> BiMap<K, V> filterKeys(
+  public static <K extends @Nullable Object, V extends @Nullable Object> BiMap<K, V> filterKeys(
       BiMap<K, V> unfiltered, final Predicate<? super K> keyPredicate) {
     checkNotNull(keyPredicate);
     return filterEntries(unfiltered, Maps.<K>keyPredicateOnEntries(keyPredicate));
@@ -2374,7 +2641,7 @@ public static <K, V> BiMap<K, V> filterKeys(
    * at {@link Predicate#apply}. Do not provide a predicate such as {@code
    * Predicates.instanceOf(ArrayList.class)}, which is inconsistent with equals.
    */
-  public static <K, V> Map<K, V> filterValues(
+  public static <K extends @Nullable Object, V extends @Nullable Object> Map<K, V> filterValues(
       Map<K, V> unfiltered, final Predicate<? super V> valuePredicate) {
     return filterEntries(unfiltered, Maps.<V>valuePredicateOnEntries(valuePredicate));
   }
@@ -2405,8 +2672,9 @@ public static <K, V> Map<K, V> filterValues(
    *
    * @since 11.0
    */
-  public static <K, V> SortedMap<K, V> filterValues(
-      SortedMap<K, V> unfiltered, final Predicate<? super V> valuePredicate) {
+  public static <K extends @Nullable Object, V extends @Nullable Object>
+      SortedMap<K, V> filterValues(
+          SortedMap<K, V> unfiltered, final Predicate<? super V> valuePredicate) {
     return filterEntries(unfiltered, Maps.<V>valuePredicateOnEntries(valuePredicate));
   }
 
@@ -2437,8 +2705,9 @@ public static <K, V> SortedMap<K, V> filterValues(
    * @since 14.0
    */
   @GwtIncompatible // NavigableMap
-  public static <K, V> NavigableMap<K, V> filterValues(
-      NavigableMap<K, V> unfiltered, final Predicate<? super V> valuePredicate) {
+  public static <K extends @Nullable Object, V extends @Nullable Object>
+      NavigableMap<K, V> filterValues(
+          NavigableMap<K, V> unfiltered, final Predicate<? super V> valuePredicate) {
     return filterEntries(unfiltered, Maps.<V>valuePredicateOnEntries(valuePredicate));
   }
 
@@ -2469,7 +2738,7 @@ public static <K, V> NavigableMap<K, V> filterValues(
    *
    * @since 14.0
    */
-  public static <K, V> BiMap<K, V> filterValues(
+  public static <K extends @Nullable Object, V extends @Nullable Object> BiMap<K, V> filterValues(
       BiMap<K, V> unfiltered, final Predicate<? super V> valuePredicate) {
     return filterEntries(unfiltered, Maps.<V>valuePredicateOnEntries(valuePredicate));
   }
@@ -2498,7 +2767,7 @@ public static <K, V> BiMap<K, V> filterValues(
    * <p><b>Warning:</b> {@code entryPredicate} must be <i>consistent with equals</i>, as documented
    * at {@link Predicate#apply}.
    */
-  public static <K, V> Map<K, V> filterEntries(
+  public static <K extends @Nullable Object, V extends @Nullable Object> Map<K, V> filterEntries(
       Map<K, V> unfiltered, Predicate<? super Entry<K, V>> entryPredicate) {
     checkNotNull(entryPredicate);
     return (unfiltered instanceof AbstractFilteredMap)
@@ -2532,8 +2801,9 @@ public static <K, V> Map<K, V> filterEntries(
    *
    * @since 11.0
    */
-  public static <K, V> SortedMap<K, V> filterEntries(
-      SortedMap<K, V> unfiltered, Predicate<? super Entry<K, V>> entryPredicate) {
+  public static <K extends @Nullable Object, V extends @Nullable Object>
+      SortedMap<K, V> filterEntries(
+          SortedMap<K, V> unfiltered, Predicate<? super Entry<K, V>> entryPredicate) {
     checkNotNull(entryPredicate);
     return (unfiltered instanceof FilteredEntrySortedMap)
         ? filterFiltered((FilteredEntrySortedMap<K, V>) unfiltered, entryPredicate)
@@ -2567,8 +2837,9 @@ public static <K, V> SortedMap<K, V> filterEntries(
    * @since 14.0
    */
   @GwtIncompatible // NavigableMap
-  public static <K, V> NavigableMap<K, V> filterEntries(
-      NavigableMap<K, V> unfiltered, Predicate<? super Entry<K, V>> entryPredicate) {
+  public static <K extends @Nullable Object, V extends @Nullable Object>
+      NavigableMap<K, V> filterEntries(
+          NavigableMap<K, V> unfiltered, Predicate<? super Entry<K, V>> entryPredicate) {
     checkNotNull(entryPredicate);
     return (unfiltered instanceof FilteredEntryNavigableMap)
         ? filterFiltered((FilteredEntryNavigableMap<K, V>) unfiltered, entryPredicate)
@@ -2602,7 +2873,7 @@ public static <K, V> NavigableMap<K, V> filterEntries(
    *
    * @since 14.0
    */
-  public static <K, V> BiMap<K, V> filterEntries(
+  public static <K extends @Nullable Object, V extends @Nullable Object> BiMap<K, V> filterEntries(
       BiMap<K, V> unfiltered, Predicate<? super Entry<K, V>> entryPredicate) {
     checkNotNull(unfiltered);
     checkNotNull(entryPredicate);
@@ -2615,7 +2886,7 @@ public static <K, V> BiMap<K, V> filterEntries(
    * Support {@code clear()}, {@code removeAll()}, and {@code retainAll()} when filtering a filtered
    * map.
    */
-  private static <K, V> Map<K, V> filterFiltered(
+  private static <K extends @Nullable Object, V extends @Nullable Object> Map<K, V> filterFiltered(
       AbstractFilteredMap<K, V> map, Predicate<? super Entry<K, V>> entryPredicate) {
     return new FilteredEntryMap<>(
         map.unfiltered, Predicates.<Entry<K, V>>and(map.predicate, entryPredicate));
@@ -2625,8 +2896,9 @@ private static <K, V> Map<K, V> filterFiltered(
    * Support {@code clear()}, {@code removeAll()}, and {@code retainAll()} when filtering a filtered
    * sorted map.
    */
-  private static <K, V> SortedMap<K, V> filterFiltered(
-      FilteredEntrySortedMap<K, V> map, Predicate<? super Entry<K, V>> entryPredicate) {
+  private static <K extends @Nullable Object, V extends @Nullable Object>
+      SortedMap<K, V> filterFiltered(
+          FilteredEntrySortedMap<K, V> map, Predicate<? super Entry<K, V>> entryPredicate) {
     Predicate<Entry<K, V>> predicate = Predicates.<Entry<K, V>>and(map.predicate, entryPredicate);
     return new FilteredEntrySortedMap<>(map.sortedMap(), predicate);
   }
@@ -2636,8 +2908,9 @@ private static <K, V> SortedMap<K, V> filterFiltered(
    * navigable map.
    */
   @GwtIncompatible // NavigableMap
-  private static <K, V> NavigableMap<K, V> filterFiltered(
-      FilteredEntryNavigableMap<K, V> map, Predicate<? super Entry<K, V>> entryPredicate) {
+  private static <K extends @Nullable Object, V extends @Nullable Object>
+      NavigableMap<K, V> filterFiltered(
+          FilteredEntryNavigableMap<K, V> map, Predicate<? super Entry<K, V>> entryPredicate) {
     Predicate<Entry<K, V>> predicate =
         Predicates.<Entry<K, V>>and(map.entryPredicate, entryPredicate);
     return new FilteredEntryNavigableMap<>(map.unfiltered, predicate);
@@ -2647,13 +2920,16 @@ private static <K, V> NavigableMap<K, V> filterFiltered(
    * Support {@code clear()}, {@code removeAll()}, and {@code retainAll()} when filtering a filtered
    * map.
    */
-  private static <K, V> BiMap<K, V> filterFiltered(
-      FilteredEntryBiMap<K, V> map, Predicate<? super Entry<K, V>> entryPredicate) {
+  private static <K extends @Nullable Object, V extends @Nullable Object>
+      BiMap<K, V> filterFiltered(
+          FilteredEntryBiMap<K, V> map, Predicate<? super Entry<K, V>> entryPredicate) {
     Predicate<Entry<K, V>> predicate = Predicates.<Entry<K, V>>and(map.predicate, entryPredicate);
     return new FilteredEntryBiMap<>(map.unfiltered(), predicate);
   }
 
-  private abstract static class AbstractFilteredMap<K, V> extends ViewCachingAbstractMap<K, V> {
+  private abstract static class AbstractFilteredMap<
+          K extends @Nullable Object, V extends @Nullable Object>
+      extends ViewCachingAbstractMap<K, V> {
     final Map<K, V> unfiltered;
     final Predicate<? super Entry<K, V>> predicate;
 
@@ -2662,16 +2938,17 @@ private abstract static class AbstractFilteredMap<K, V> extends ViewCachingAbstr
       this.predicate = predicate;
     }
 
-    boolean apply(@Nullable Object key, @Nullable V value) {
-      // This method is called only when the key is in the map, implying that
-      // key is a K.
-      @SuppressWarnings("unchecked")
+    boolean apply(@CheckForNull Object key, @ParametricNullness V value) {
+      // This method is called only when the key is in the map (or about to be added to the map),
+      // implying that key is a K.
+      @SuppressWarnings({"unchecked", "nullness"})
       K k = (K) key;
       return predicate.apply(Maps.immutableEntry(k, value));
     }
 
     @Override
-    public V put(K key, V value) {
+    @CheckForNull
+    public V put(@ParametricNullness K key, @ParametricNullness V value) {
       checkArgument(apply(key, value));
       return unfiltered.put(key, value);
     }
@@ -2686,12 +2963,13 @@ public void putAll(Map<? extends K, ? extends V> map) {
 
     @Pure
     @Override
-    public boolean containsKey(@Nullable Object key) {
+    public boolean containsKey(@CheckForNull Object key) {
       return unfiltered.containsKey(key) && apply(key, unfiltered.get(key));
     }
 
     @Override
-    public @Nullable V get(@Nullable Object key) {
+    @CheckForNull
+    public V get(@CheckForNull Object key) {
       V value = unfiltered.get(key);
       return ((value != null) && apply(key, value)) ? value : null;
     }
@@ -2703,7 +2981,8 @@ public boolean isEmpty() {
     }
 
     @Override
-    public @Nullable V remove(@Nullable Object key) {
+    @CheckForNull
+    public V remove(@CheckForNull Object key) {
       return containsKey(key) ? unfiltered.remove(key) : null;
     }
 
@@ -2713,7 +2992,9 @@ Collection<V> createValues() {
     }
   }
 
-  private static final class FilteredMapValues<K, V> extends Maps.Values<K, V> {
+  private static final class FilteredMapValues<
+          K extends @Nullable Object, V extends @Nullable Object>
+      extends Maps.Values<K, V> {
     final Map<K, V> unfiltered;
     final Predicate<? super Entry<K, V>> predicate;
 
@@ -2725,7 +3006,7 @@ private static final class FilteredMapValues<K, V> extends Maps.Values<K, V> {
     }
 
     @Override
-    public boolean remove(Object o) {
+    public boolean remove(@CheckForNull Object o) {
       Iterator<Entry<K, V>> entryItr = unfiltered.entrySet().iterator();
       while (entryItr.hasNext()) {
         Entry<K, V> entry = entryItr.next();
@@ -2766,18 +3047,20 @@ public boolean retainAll(Collection<?> collection) {
     }
 
     @Override
-    public Object[] toArray() {
+    public @Nullable Object[] toArray() {
       // creating an ArrayList so filtering happens once
       return Lists.newArrayList(iterator()).toArray();
     }
 
     @Override
-    public <T> T[] toArray(T[] array) {
+    @SuppressWarnings("nullness") // b/192354773 in our checker affects toArray declarations
+    public <T extends @Nullable Object> T[] toArray(T[] array) {
       return Lists.newArrayList(iterator()).toArray(array);
     }
   }
 
-  private static class FilteredKeyMap<K, V> extends AbstractFilteredMap<K, V> {
+  private static class FilteredKeyMap<K extends @Nullable Object, V extends @Nullable Object>
+      extends AbstractFilteredMap<K, V> {
     final Predicate<? super K> keyPredicate;
 
     FilteredKeyMap(
@@ -2803,12 +3086,13 @@ Set<K> createKeySet() {
     @Pure
     @Override
     @SuppressWarnings("unchecked")
-    public boolean containsKey(@Nullable Object key) {
+    public boolean containsKey(@CheckForNull Object key) {
       return unfiltered.containsKey(key) && keyPredicate.apply((K) key);
     }
   }
 
-  static class FilteredEntryMap<K, V> extends AbstractFilteredMap<K, V> {
+  static class FilteredEntryMap<K extends @Nullable Object, V extends @Nullable Object>
+      extends AbstractFilteredMap<K, V> {
     /**
      * Entries in this set satisfy the predicate, but they don't validate the input to {@code
      * Entry.setValue()}.
@@ -2844,7 +3128,8 @@ protected Entry<K, V> delegate() {
               }
 
               @Override
-              public V setValue(V newValue) {
+              @ParametricNullness
+              public V setValue(@ParametricNullness V newValue) {
                 checkArgument(apply(getKey(), newValue));
                 return super.setValue(newValue);
               }
@@ -2859,7 +3144,7 @@ Set<K> createKeySet() {
       return new KeySet();
     }
 
-    static <K, V> boolean removeAllKeys(
+    static <K extends @Nullable Object, V extends @Nullable Object> boolean removeAllKeys(
         Map<K, V> map, Predicate<? super Entry<K, V>> entryPredicate, Collection<?> keyCollection) {
       Iterator<Entry<K, V>> entryItr = map.entrySet().iterator();
       boolean result = false;
@@ -2873,7 +3158,7 @@ static <K, V> boolean removeAllKeys(
       return result;
     }
 
-    static <K, V> boolean retainAllKeys(
+    static <K extends @Nullable Object, V extends @Nullable Object> boolean retainAllKeys(
         Map<K, V> map, Predicate<? super Entry<K, V>> entryPredicate, Collection<?> keyCollection) {
       Iterator<Entry<K, V>> entryItr = map.entrySet().iterator();
       boolean result = false;
@@ -2894,7 +3179,7 @@ class KeySet extends Maps.KeySet<K, V> {
       }
 
       @Override
-      public boolean remove(@Nullable Object o) {
+      public boolean remove(@CheckForNull Object o) {
         if (containsKey(o)) {
           unfiltered.remove(o);
           return true;
@@ -2913,13 +3198,14 @@ public boolean retainAll(Collection<?> collection) {
       }
 
       @Override
-      public Object[] toArray() {
+      public @Nullable Object[] toArray() {
         // creating an ArrayList so filtering happens once
         return Lists.newArrayList(iterator()).toArray();
       }
 
       @Override
-      public <T> T[] toArray(T[] array) {
+      @SuppressWarnings("nullness") // b/192354773 in our checker affects toArray declarations
+      public <T extends @Nullable Object> T[] toArray(T[] array) {
         return Lists.newArrayList(iterator()).toArray(array);
       }
 
@@ -2929,8 +3215,9 @@ public <T> T[] toArray(T[] array) {
     }
   }
 
-  private static class FilteredEntrySortedMap<K, V> extends FilteredEntryMap<K, V>
-      implements SortedMap<K, V> {
+  private static class FilteredEntrySortedMap<
+          K extends @Nullable Object, V extends @Nullable Object>
+      extends FilteredEntryMap<K, V> implements SortedMap<K, V> {
 
     FilteredEntrySortedMap(
         SortedMap<K, V> unfiltered, Predicate<? super Entry<K, V>> entryPredicate) {
@@ -2954,54 +3241,62 @@ SortedSet<K> createKeySet() {
     @WeakOuter
     class SortedKeySet extends KeySet implements SortedSet<K> {
       @Override
+      @CheckForNull
       public Comparator<? super K> comparator() {
         return sortedMap().comparator();
       }
 
       @Override
-      public SortedSet<K> subSet(K fromElement, K toElement) {
+      public SortedSet<K> subSet(
+          @ParametricNullness K fromElement, @ParametricNullness K toElement) {
         return (SortedSet<K>) subMap(fromElement, toElement).keySet();
       }
 
       @Override
-      public SortedSet<K> headSet(K toElement) {
+      public SortedSet<K> headSet(@ParametricNullness K toElement) {
         return (SortedSet<K>) headMap(toElement).keySet();
       }
 
       @Override
-      public SortedSet<K> tailSet(K fromElement) {
+      public SortedSet<K> tailSet(@ParametricNullness K fromElement) {
         return (SortedSet<K>) tailMap(fromElement).keySet();
       }
 
       @Override
+      @ParametricNullness
       public K first() {
         return firstKey();
       }
 
       @Override
+      @ParametricNullness
       public K last() {
         return lastKey();
       }
     }
 
     @Override
+    @CheckForNull
     public Comparator<? super K> comparator() {
       return sortedMap().comparator();
     }
 
     @Override
+    @ParametricNullness
     public K firstKey() {
       // correctly throws NoSuchElementException when filtered map is empty.
       return keySet().iterator().next();
     }
 
     @Override
+    @ParametricNullness
     public K lastKey() {
       SortedMap<K, V> headMap = sortedMap();
       while (true) {
         // correctly throws NoSuchElementException when filtered map is empty.
         K key = headMap.lastKey();
-        if (apply(key, unfiltered.get(key))) {
+        // The cast is safe because the key is taken from the map.
+        if (apply(key, uncheckedCastNullableTToT(unfiltered.get(key)))) {
           return key;
         }
         headMap = sortedMap().headMap(key);
@@ -3009,23 +3304,25 @@ public K lastKey() {
     }
 
     @Override
-    public SortedMap<K, V> headMap(K toKey) {
+    public SortedMap<K, V> headMap(@ParametricNullness K toKey) {
       return new FilteredEntrySortedMap<>(sortedMap().headMap(toKey), predicate);
     }
 
     @Override
-    public SortedMap<K, V> subMap(K fromKey, K toKey) {
+    public SortedMap<K, V> subMap(@ParametricNullness K fromKey, @ParametricNullness K toKey) {
       return new FilteredEntrySortedMap<>(sortedMap().subMap(fromKey, toKey), predicate);
     }
 
     @Override
-    public SortedMap<K, V> tailMap(K fromKey) {
+    public SortedMap<K, V> tailMap(@ParametricNullness K fromKey) {
       return new FilteredEntrySortedMap<>(sortedMap().tailMap(fromKey), predicate);
     }
   }
 
   @GwtIncompatible // NavigableMap
-  private static class FilteredEntryNavigableMap<K, V> extends AbstractNavigableMap<K, V> {
+  private static class FilteredEntryNavigableMap<
+          K extends @Nullable Object, V extends @Nullable Object>
+      extends AbstractNavigableMap<K, V> {
     /*
      * It's less code to extend AbstractNavigableMap and forward the filtering logic to
      * FilteredEntryMap than to extend FilteredEntrySortedMap and reimplement all the NavigableMap
@@ -3044,6 +3341,7 @@ private static class FilteredEntryNavigableMap<K, V> extends AbstractNavigableMa
     }
 
     @Override
+    @CheckForNull
     public Comparator<? super K> comparator() {
       return unfiltered.comparator();
     }
@@ -3089,22 +3387,25 @@ public boolean isEmpty() {
     }
 
     @Override
-    public @Nullable V get(@Nullable Object key) {
+    @CheckForNull
+    public V get(@CheckForNull Object key) {
       return filteredDelegate.get(key);
     }
 
     @Override
-    public boolean containsKey(@Nullable Object key) {
+    public boolean containsKey(@CheckForNull Object key) {
       return filteredDelegate.containsKey(key);
     }
 
     @Override
-    public V put(K key, V value) {
+    @CheckForNull
+    public V put(@ParametricNullness K key, @ParametricNullness V value) {
       return filteredDelegate.put(key, value);
     }
 
     @Override
-    public V remove(@Nullable Object key) {
+    @CheckForNull
+    public V remove(@CheckForNull Object key) {
       return filteredDelegate.remove(key);
     }
 
@@ -3124,11 +3425,13 @@ public Set<Entry<K, V>> entrySet() {
     }
 
     @Override
+    @CheckForNull
     public Entry<K, V> pollFirstEntry() {
       return Iterables.removeFirstMatching(unfiltered.entrySet(), entryPredicate);
     }
 
     @Override
+    @CheckForNull
     public Entry<K, V> pollLastEntry() {
       return Iterables.removeFirstMatching(unfiltered.descendingMap().entrySet(), entryPredicate);
     }
@@ -3140,28 +3443,32 @@ public NavigableMap<K, V> descendingMap() {
 
     @Override
     public NavigableMap<K, V> subMap(
-        K fromKey, boolean fromInclusive, K toKey, boolean toInclusive) {
+        @ParametricNullness K fromKey,
+        boolean fromInclusive,
+        @ParametricNullness K toKey,
+        boolean toInclusive) {
       return filterEntries(
           unfiltered.subMap(fromKey, fromInclusive, toKey, toInclusive), entryPredicate);
     }
 
     @Override
-    public NavigableMap<K, V> headMap(K toKey, boolean inclusive) {
+    public NavigableMap<K, V> headMap(@ParametricNullness K toKey, boolean inclusive) {
       return filterEntries(unfiltered.headMap(toKey, inclusive), entryPredicate);
     }
 
     @Override
-    public NavigableMap<K, V> tailMap(K fromKey, boolean inclusive) {
+    public NavigableMap<K, V> tailMap(@ParametricNullness K fromKey, boolean inclusive) {
       return filterEntries(unfiltered.tailMap(fromKey, inclusive), entryPredicate);
     }
   }
 
-  static final class FilteredEntryBiMap<K, V> extends FilteredEntryMap<K, V>
-      implements BiMap<K, V> {
+  static final class FilteredEntryBiMap<K extends @Nullable Object, V extends @Nullable Object>
+      extends FilteredEntryMap<K, V> implements BiMap<K, V> {
     @RetainedWith private final BiMap<V, K> inverse;
 
-    private static <K, V> Predicate<Entry<V, K>> inversePredicate(
-        final Predicate<? super Entry<K, V>> forwardPredicate) {
+    private static <K extends @Nullable Object, V extends @Nullable Object>
+        Predicate<Entry<V, K>> inversePredicate(
+            final Predicate<? super Entry<K, V>> forwardPredicate) {
       return new Predicate<Entry<V, K>>() {
         @Override
         public boolean apply(Entry<V, K> input) {
@@ -3187,7 +3494,8 @@ BiMap<K, V> unfiltered() {
     }
 
     @Override
-    public V forcePut(@Nullable K key, @Nullable V value) {
+    @CheckForNull
+    public V forcePut(@ParametricNullness K key, @ParametricNullness V value) {
       checkArgument(apply(key, value));
       return unfiltered().forcePut(key, value);
     }
@@ -3232,8 +3540,8 @@ public Set<V> values() {
    * @since 12.0
    */
   @GwtIncompatible // NavigableMap
-  public static <K, V> NavigableMap<K, V> unmodifiableNavigableMap(
-      NavigableMap<K, ? extends V> map) {
+  public static <K extends @Nullable Object, V extends @Nullable Object>
+      NavigableMap<K, V> unmodifiableNavigableMap(NavigableMap<K, ? extends V> map) {
     checkNotNull(map);
     if (map instanceof UnmodifiableNavigableMap) {
       @SuppressWarnings("unchecked") // covariant
@@ -3244,14 +3552,15 @@ public static <K, V> NavigableMap<K, V> unmodifiableNavigableMap(
     }
   }
 
-  private static <K, V> @Nullable Entry<K, V> unmodifiableOrNull(
-      @Nullable Entry<K, ? extends V> entry) {
+  @CheckForNull
+  private static <K extends @Nullable Object, V extends @Nullable Object>
+      Entry<K, V> unmodifiableOrNull(@CheckForNull Entry<K, ? extends V> entry) {
     return (entry == null) ? null : Maps.unmodifiableEntry(entry);
   }
 
   @GwtIncompatible // NavigableMap
-  static class UnmodifiableNavigableMap<K, V> extends ForwardingSortedMap<K, V>
-      implements NavigableMap<K, V>, Serializable {
+  static class UnmodifiableNavigableMap<K extends @Nullable Object, V extends @Nullable Object>
+      extends ForwardingSortedMap<K, V> implements NavigableMap<K, V>, Serializable {
     private final NavigableMap<K, ? extends V> delegate;
 
     UnmodifiableNavigableMap(NavigableMap<K, ? extends V> delegate) {
@@ -3270,66 +3579,129 @@ protected SortedMap<K, V> delegate() {
     }
 
     @Override
-    public Entry<K, V> lowerEntry(K key) {
+    @CheckForNull
+    public Entry<K, V> lowerEntry(@ParametricNullness K key) {
       return unmodifiableOrNull(delegate.lowerEntry(key));
     }
 
     @Override
-    public K lowerKey(K key) {
+    @CheckForNull
+    public K lowerKey(@ParametricNullness K key) {
       return delegate.lowerKey(key);
     }
 
     @Override
-    public Entry<K, V> floorEntry(K key) {
+    @CheckForNull
+    public Entry<K, V> floorEntry(@ParametricNullness K key) {
       return unmodifiableOrNull(delegate.floorEntry(key));
     }
 
     @Override
-    public K floorKey(K key) {
+    @CheckForNull
+    public K floorKey(@ParametricNullness K key) {
       return delegate.floorKey(key);
     }
 
     @Override
-    public Entry<K, V> ceilingEntry(K key) {
+    @CheckForNull
+    public Entry<K, V> ceilingEntry(@ParametricNullness K key) {
       return unmodifiableOrNull(delegate.ceilingEntry(key));
     }
 
     @Override
-    public K ceilingKey(K key) {
+    @CheckForNull
+    public K ceilingKey(@ParametricNullness K key) {
       return delegate.ceilingKey(key);
     }
 
     @Override
-    public Entry<K, V> higherEntry(K key) {
+    @CheckForNull
+    public Entry<K, V> higherEntry(@ParametricNullness K key) {
       return unmodifiableOrNull(delegate.higherEntry(key));
     }
 
     @Override
-    public K higherKey(K key) {
+    @CheckForNull
+    public K higherKey(@ParametricNullness K key) {
       return delegate.higherKey(key);
     }
 
     @Override
+    @CheckForNull
     public Entry<K, V> firstEntry() {
       return unmodifiableOrNull(delegate.firstEntry());
     }
 
     @Override
+    @CheckForNull
     public Entry<K, V> lastEntry() {
       return unmodifiableOrNull(delegate.lastEntry());
     }
 
     @Override
+    @CheckForNull
     public final Entry<K, V> pollFirstEntry() {
       throw new UnsupportedOperationException();
     }
 
     @Override
+    @CheckForNull
     public final Entry<K, V> pollLastEntry() {
       throw new UnsupportedOperationException();
     }
 
-    private transient @Nullable UnmodifiableNavigableMap<K, V> descendingMap;
+    @Override
+    public void replaceAll(BiFunction<? super K, ? super V, ? extends V> function) {
+      throw new UnsupportedOperationException();
+    }
+
+    @Override
+    @CheckForNull
+    public V putIfAbsent(K key, V value) {
+      throw new UnsupportedOperationException();
+    }
+
+    @Override
+    public boolean remove(@Nullable Object key, @Nullable Object value) {
+      throw new UnsupportedOperationException();
+    }
+
+    @Override
+    public boolean replace(K key, V oldValue, V newValue) {
+      throw new UnsupportedOperationException();
+    }
+
+    @Override
+    @CheckForNull
+    public V replace(K key, V value) {
+      throw new UnsupportedOperationException();
+    }
+
+    @Override
+    public V computeIfAbsent(
+        K key, java.util.function.Function<? super K, ? extends V> mappingFunction) {
+      throw new UnsupportedOperationException();
+    }
+
+    @Override
+    public V computeIfPresent(
+        K key, BiFunction<? super K, ? super V, ? extends V> remappingFunction) {
+      throw new UnsupportedOperationException();
+    }
+
+    @Override
+    public V compute(
+        K key, BiFunction<? super K, ? super @Nullable V, ? extends V> remappingFunction) {
+      throw new UnsupportedOperationException();
+    }
+
+    @Override
+    public V merge(
+        K key, V value, BiFunction<? super V, ? super V, ? extends V> remappingFunction) {
+      throw new UnsupportedOperationException();
+    }
+
+    @CheckForNull private transient UnmodifiableNavigableMap<K, V> descendingMap;
 
     @Override
     public NavigableMap<K, V> descendingMap() {
@@ -3355,34 +3727,37 @@ public NavigableSet<K> descendingKeySet() {
     }
 
     @Override
-    public SortedMap<K, V> subMap(K fromKey, K toKey) {
+    public SortedMap<K, V> subMap(@ParametricNullness K fromKey, @ParametricNullness K toKey) {
       return subMap(fromKey, true, toKey, false);
     }
 
     @Override
     public NavigableMap<K, V> subMap(
-        K fromKey, boolean fromInclusive, K toKey, boolean toInclusive) {
+        @ParametricNullness K fromKey,
+        boolean fromInclusive,
+        @ParametricNullness K toKey,
+        boolean toInclusive) {
       return Maps.unmodifiableNavigableMap(
           delegate.subMap(fromKey, fromInclusive, toKey, toInclusive));
     }
 
     @Override
-    public SortedMap<K, V> headMap(K toKey) {
+    public SortedMap<K, V> headMap(@ParametricNullness K toKey) {
       return headMap(toKey, false);
     }
 
     @Override
-    public NavigableMap<K, V> headMap(K toKey, boolean inclusive) {
+    public NavigableMap<K, V> headMap(@ParametricNullness K toKey, boolean inclusive) {
       return Maps.unmodifiableNavigableMap(delegate.headMap(toKey, inclusive));
     }
 
     @Override
-    public SortedMap<K, V> tailMap(K fromKey) {
+    public SortedMap<K, V> tailMap(@ParametricNullness K fromKey) {
       return tailMap(fromKey, true);
     }
 
     @Override
-    public NavigableMap<K, V> tailMap(K fromKey, boolean inclusive) {
+    public NavigableMap<K, V> tailMap(@ParametricNullness K fromKey, boolean inclusive) {
       return Maps.unmodifiableNavigableMap(delegate.tailMap(fromKey, inclusive));
     }
   }
@@ -3437,8 +3812,8 @@ public NavigableMap<K, V> tailMap(K fromKey, boolean inclusive) {
    * @since 13.0
    */
   @GwtIncompatible // NavigableMap
-  public static <K, V> NavigableMap<K, V> synchronizedNavigableMap(
-      NavigableMap<K, V> navigableMap) {
+  public static <K extends @Nullable Object, V extends @Nullable Object>
+      NavigableMap<K, V> synchronizedNavigableMap(NavigableMap<K, V> navigableMap) {
     return Synchronized.navigableMap(navigableMap);
   }
 
@@ -3447,14 +3822,16 @@ public static <K, V> NavigableMap<K, V> synchronizedNavigableMap(
    * entrySet views.
    */
   @GwtCompatible
-  abstract static class ViewCachingAbstractMap<K, V> extends AbstractMap<K, V> {
+  abstract static class ViewCachingAbstractMap<
+          K extends @Nullable Object, V extends @Nullable Object>
+      extends AbstractMap<K, V> {
     /**
      * Creates the entry set to be returned by {@link #entrySet()}. This method is invoked at most
      * once on a given map, at the time when {@code entrySet} is first called.
      */
     abstract Set<Entry<K, V>> createEntrySet();
 
-    private transient @Nullable Set<Entry<K, V>> entrySet;
+    @CheckForNull private transient Set<Entry<K, V>> entrySet;
 
     @Override
     public Set<Entry<K, V>> entrySet() {
@@ -3462,7 +3839,7 @@ public Set<Entry<K, V>> entrySet() {
       return (result == null) ? entrySet = createEntrySet() : result;
     }
 
-    private transient @Nullable Set<K> keySet;
+    @CheckForNull private transient Set<K> keySet;
 
     @Override
     public Set<K> keySet() {
@@ -3474,7 +3851,7 @@ Set<K> createKeySet() {
       return new KeySet<>(this);
     }
 
-    private transient @Nullable Collection<V> values;
+    @CheckForNull private transient Collection<V> values;
 
     @Override
     public Collection<V> values() {
@@ -3487,7 +3864,9 @@ Collection<V> createValues() {
     }
   }
 
-  abstract static class IteratorBasedAbstractMap<K, V> extends AbstractMap<K, V> {
+  abstract static class IteratorBasedAbstractMap<
+          K extends @Nullable Object, V extends @Nullable Object>
+      extends AbstractMap<K, V> {
     @Override
     public abstract int size();
 
@@ -3537,7 +3916,8 @@ public void clear() {
    * Delegates to {@link Map#get}. Returns {@code null} on {@code ClassCastException} and {@code
    * NullPointerException}.
    */
-  static <V> V safeGet(Map<?, V> map, @Nullable Object key) {
+  @CheckForNull
+  static <V extends @Nullable Object> V safeGet(Map<?, V> map, @CheckForNull Object key) {
     checkNotNull(map);
     try {
       return map.get(key);
@@ -3550,7 +3930,7 @@ static <V> V safeGet(Map<?, V> map, @Nullable Object key) {
    * Delegates to {@link Map#containsKey}. Returns {@code false} on {@code ClassCastException} and
    * {@code NullPointerException}.
    */
-  static boolean safeContainsKey(Map<?, ?> map, Object key) {
+  static boolean safeContainsKey(Map<?, ?> map, @CheckForNull Object key) {
     checkNotNull(map);
     try {
       return map.containsKey(key);
@@ -3563,7 +3943,8 @@ static boolean safeContainsKey(Map<?, ?> map, Object key) {
    * Delegates to {@link Map#remove}. Returns {@code null} on {@code ClassCastException} and {@code
    * NullPointerException}.
    */
-  static <V> V safeRemove(Map<?, V> map, Object key) {
+  @CheckForNull
+  static <V extends @Nullable Object> V safeRemove(Map<?, V> map, @CheckForNull Object key) {
     checkNotNull(map);
     try {
       return map.remove(key);
@@ -3573,12 +3954,12 @@ static <V> V safeRemove(Map<?, V> map, Object key) {
   }
 
   /** An admittedly inefficient implementation of {@link Map#containsKey}. */
-  static boolean containsKeyImpl(Map<?, ?> map, @Nullable Object key) {
+  static boolean containsKeyImpl(Map<?, ?> map, @CheckForNull Object key) {
     return Iterators.contains(keyIterator(map.entrySet().iterator()), key);
   }
 
   /** An implementation of {@link Map#containsValue}. */
-  static boolean containsValueImpl(Map<?, ?> map, @Nullable Object value) {
+  static boolean containsValueImpl(Map<?, ?> map, @CheckForNull Object value) {
     return Iterators.contains(valueIterator(map.entrySet().iterator()), value);
   }
 
@@ -3595,7 +3976,8 @@ static boolean containsValueImpl(Map<?, ?> map, @Nullable Object value) {
    * @return {@code true} if {@code c} contains {@code o}
    */
   @Pure
-  static <K, V> boolean containsEntryImpl(Collection<Entry<K, V>> c, @Nullable Object o) {
+  static <K extends @Nullable Object, V extends @Nullable Object> boolean containsEntryImpl(
+      Collection<Entry<K, V>> c, @CheckForNull Object o) {
     if (!(o instanceof Entry)) {
       return false;
     }
@@ -3613,7 +3995,8 @@ static <K, V> boolean containsEntryImpl(Collection<Entry<K, V>> c, @Nullable Obj
    * @param o the object to remove from {@code c}
    * @return {@code true} if {@code c} was changed
    */
-  static <K, V> boolean removeEntryImpl(Collection<Entry<K, V>> c, @Nullable Object o) {
+  static <K extends @Nullable Object, V extends @Nullable Object> boolean removeEntryImpl(
+      Collection<Entry<K, V>> c, @CheckForNull Object o) {
     if (!(o instanceof Entry)) {
       return false;
     }
@@ -3621,7 +4004,7 @@ static <K, V> boolean removeEntryImpl(Collection<Entry<K, V>> c, @Nullable Objec
   }
 
   /** An implementation of {@link Map#equals}. */
-  static boolean equalsImpl(Map<?, ?> map, Object object) {
+  static boolean equalsImpl(Map<?, ?> map, @CheckForNull Object object) {
     if (map == object) {
       return true;
     } else if (object instanceof Map) {
@@ -3646,13 +4029,15 @@ static String toStringImpl(Map<?, ?> map) {
   }
 
   /** An implementation of {@link Map#putAll}. */
-  static <K, V> void putAllImpl(Map<K, V> self, Map<? extends K, ? extends V> map) {
+  static <K extends @Nullable Object, V extends @Nullable Object> void putAllImpl(
+      Map<K, V> self, Map<? extends K, ? extends V> map) {
     for (Entry<? extends K, ? extends V> entry : map.entrySet()) {
       self.put(entry.getKey(), entry.getValue());
     }
   }
 
-  static class KeySet<K, V> extends Sets.ImprovedAbstractSet<K> {
+  static class KeySet<K extends @Nullable Object, V extends @Nullable Object>
+      extends Sets.ImprovedAbstractSet<K> {
     @Weak final Map<K, V> map;
 
     KeySet(Map<K, V> map) {
@@ -3686,12 +4071,12 @@ public boolean isEmpty() {
     }
 
     @Override
-    public boolean contains(Object o) {
+    public boolean contains(@CheckForNull Object o) {
       return map().containsKey(o);
     }
 
     @Override
-    public boolean remove(Object o) {
+    public boolean remove(@CheckForNull Object o) {
       if (contains(o)) {
         map().remove(o);
         return true;
@@ -3705,15 +4090,18 @@ public void clear() {
     }
   }
 
-  static <K> @Nullable K keyOrNull(@Nullable Entry<K, ?> entry) {
+  @CheckForNull
+  static <K extends @Nullable Object> K keyOrNull(@CheckForNull Entry<K, ?> entry) {
     return (entry == null) ? null : entry.getKey();
   }
 
-  static <V> @Nullable V valueOrNull(@Nullable Entry<?, V> entry) {
+  @CheckForNull
+  static <V extends @Nullable Object> V valueOrNull(@CheckForNull Entry<?, V> entry) {
     return (entry == null) ? null : entry.getValue();
   }
 
-  static class SortedKeySet<K, V> extends KeySet<K, V> implements SortedSet<K> {
+  static class SortedKeySet<K extends @Nullable Object, V extends @Nullable Object>
+      extends KeySet<K, V> implements SortedSet<K> {
     SortedKeySet(SortedMap<K, V> map) {
       super(map);
     }
@@ -3724,38 +4112,42 @@ SortedMap<K, V> map() {
     }
 
     @Override
+    @CheckForNull
     public Comparator<? super K> comparator() {
       return map().comparator();
     }
 
     @Override
-    public SortedSet<K> subSet(K fromElement, K toElement) {
+    public SortedSet<K> subSet(@ParametricNullness K fromElement, @ParametricNullness K toElement) {
       return new SortedKeySet<>(map().subMap(fromElement, toElement));
     }
 
     @Override
-    public SortedSet<K> headSet(K toElement) {
+    public SortedSet<K> headSet(@ParametricNullness K toElement) {
       return new SortedKeySet<>(map().headMap(toElement));
     }
 
     @Override
-    public SortedSet<K> tailSet(K fromElement) {
+    public SortedSet<K> tailSet(@ParametricNullness K fromElement) {
       return new SortedKeySet<>(map().tailMap(fromElement));
     }
 
     @Override
+    @ParametricNullness
     public K first() {
       return map().firstKey();
     }
 
     @Override
+    @ParametricNullness
     public K last() {
       return map().lastKey();
     }
   }
 
   @GwtIncompatible // NavigableMap
-  static class NavigableKeySet<K, V> extends SortedKeySet<K, V> implements NavigableSet<K> {
+  static class NavigableKeySet<K extends @Nullable Object, V extends @Nullable Object>
+      extends SortedKeySet<K, V> implements NavigableSet<K> {
     NavigableKeySet(NavigableMap<K, V> map) {
       super(map);
     }
@@ -3766,31 +4158,37 @@ NavigableMap<K, V> map() {
     }
 
     @Override
-    public K lower(K e) {
+    @CheckForNull
+    public K lower(@ParametricNullness K e) {
       return map().lowerKey(e);
     }
 
     @Override
-    public K floor(K e) {
+    @CheckForNull
+    public K floor(@ParametricNullness K e) {
       return map().floorKey(e);
     }
 
     @Override
-    public K ceiling(K e) {
+    @CheckForNull
+    public K ceiling(@ParametricNullness K e) {
       return map().ceilingKey(e);
     }
 
     @Override
-    public K higher(K e) {
+    @CheckForNull
+    public K higher(@ParametricNullness K e) {
       return map().higherKey(e);
     }
 
     @Override
+    @CheckForNull
     public K pollFirst() {
       return keyOrNull(map().pollFirstEntry());
     }
 
     @Override
+    @CheckForNull
     public K pollLast() {
       return keyOrNull(map().pollLastEntry());
     }
@@ -3807,37 +4205,41 @@ public Iterator<K> descendingIterator() {
 
     @Override
     public NavigableSet<K> subSet(
-        K fromElement, boolean fromInclusive, K toElement, boolean toInclusive) {
+        @ParametricNullness K fromElement,
+        boolean fromInclusive,
+        @ParametricNullness K toElement,
+        boolean toInclusive) {
       return map().subMap(fromElement, fromInclusive, toElement, toInclusive).navigableKeySet();
     }
 
     @Override
-    public SortedSet<K> subSet(K fromElement, K toElement) {
+    public SortedSet<K> subSet(@ParametricNullness K fromElement, @ParametricNullness K toElement) {
       return subSet(fromElement, true, toElement, false);
     }
 
     @Override
-    public NavigableSet<K> headSet(K toElement, boolean inclusive) {
+    public NavigableSet<K> headSet(@ParametricNullness K toElement, boolean inclusive) {
       return map().headMap(toElement, inclusive).navigableKeySet();
     }
 
     @Override
-    public SortedSet<K> headSet(K toElement) {
+    public SortedSet<K> headSet(@ParametricNullness K toElement) {
       return headSet(toElement, false);
     }
 
     @Override
-    public NavigableSet<K> tailSet(K fromElement, boolean inclusive) {
+    public NavigableSet<K> tailSet(@ParametricNullness K fromElement, boolean inclusive) {
       return map().tailMap(fromElement, inclusive).navigableKeySet();
     }
 
     @Override
-    public SortedSet<K> tailSet(K fromElement) {
+    public SortedSet<K> tailSet(@ParametricNullness K fromElement) {
       return tailSet(fromElement, true);
     }
   }
 
-  static class Values<K, V> extends AbstractCollection<V> {
+  static class Values<K extends @Nullable Object, V extends @Nullable Object>
+      extends AbstractCollection<V> {
     @Weak final Map<K, V> map;
 
     Values(Map<K, V> map) {
@@ -3861,7 +4263,7 @@ public void forEach(Consumer<? super V> action) {
     }
 
     @Override
-    public boolean remove(Object o) {
+    public boolean remove(@CheckForNull Object o) {
       try {
         return super.remove(o);
       } catch (UnsupportedOperationException e) {
@@ -3916,7 +4318,7 @@ public boolean isEmpty() {
     }
 
     @Override
-    public boolean contains(@Nullable Object o) {
+    public boolean contains(@CheckForNull Object o) {
       return map().containsValue(o);
     }
 
@@ -3926,7 +4328,8 @@ public void clear() {
     }
   }
 
-  abstract static class EntrySet<K, V> extends Sets.ImprovedAbstractSet<Entry<K, V>> {
+  abstract static class EntrySet<K extends @Nullable Object, V extends @Nullable Object>
+      extends Sets.ImprovedAbstractSet<Entry<K, V>> {
     abstract Map<K, V> map();
 
     @Override
@@ -3940,7 +4343,7 @@ public void clear() {
     }
 
     @Override
-    public boolean contains(Object o) {
+    public boolean contains(@CheckForNull Object o) {
       if (o instanceof Entry) {
         Entry<?, ?> entry = (Entry<?, ?>) o;
         Object key = entry.getKey();
@@ -3956,8 +4359,12 @@ public boolean isEmpty() {
     }
 
     @Override
-    public boolean remove(Object o) {
-      if (contains(o)) {
+    public boolean remove(@CheckForNull Object o) {
+      /*
+       * `o instanceof Entry` is guaranteed by `contains`, but we check it here to satisfy our
+       * nullness checker.
+       */
+      if (contains(o) && o instanceof Entry) {
         Entry<?, ?> entry = (Entry<?, ?>) o;
         return map().keySet().remove(entry.getKey());
       }
@@ -3980,9 +4387,13 @@ public boolean retainAll(Collection<?> c) {
         return super.retainAll(checkNotNull(c));
       } catch (UnsupportedOperationException e) {
         // if the iterators don't support remove
-        Set<Object> keys = Sets.newHashSetWithExpectedSize(c.size());
+        Set<@Nullable Object> keys = Sets.newHashSetWithExpectedSize(c.size());
         for (Object o : c) {
-          if (contains(o)) {
+          /*
+           * `o instanceof Entry` is guaranteed by `contains`, but we check it here to satisfy our
+           * nullness checker.
+           */
+          if (contains(o) && o instanceof Entry) {
             Entry<?, ?> entry = (Entry<?, ?>) o;
             keys.add(entry.getKey());
           }
@@ -3993,8 +4404,8 @@ public boolean retainAll(Collection<?> c) {
   }
 
   @GwtIncompatible // NavigableMap
-  abstract static class DescendingMap<K, V> extends ForwardingMap<K, V>
-      implements NavigableMap<K, V> {
+  abstract static class DescendingMap<K extends @Nullable Object, V extends @Nullable Object>
+      extends ForwardingMap<K, V> implements NavigableMap<K, V> {
 
     abstract NavigableMap<K, V> forward();
 
@@ -4003,7 +4414,7 @@ protected final Map<K, V> delegate() {
       return forward();
     }
 
-    private transient @Nullable Comparator<? super K> comparator;
+    @CheckForNull private transient Comparator<? super K> comparator;
 
     @SuppressWarnings("unchecked")
     @Override
@@ -4020,76 +4431,90 @@ public Comparator<? super K> comparator() {
     }
 
     // If we inline this, we get a javac error.
-    private static <T> Ordering<T> reverse(Comparator<T> forward) {
+    private static <T extends @Nullable Object> Ordering<T> reverse(Comparator<T> forward) {
       return Ordering.from(forward).reverse();
     }
 
     @Override
+    @ParametricNullness
     public K firstKey() {
       return forward().lastKey();
     }
 
     @Override
+    @ParametricNullness
     public K lastKey() {
       return forward().firstKey();
     }
 
     @Override
-    public Entry<K, V> lowerEntry(K key) {
+    @CheckForNull
+    public Entry<K, V> lowerEntry(@ParametricNullness K key) {
       return forward().higherEntry(key);
     }
 
     @Override
-    public K lowerKey(K key) {
+    @CheckForNull
+    public K lowerKey(@ParametricNullness K key) {
       return forward().higherKey(key);
     }
 
     @Override
-    public Entry<K, V> floorEntry(K key) {
+    @CheckForNull
+    public Entry<K, V> floorEntry(@ParametricNullness K key) {
       return forward().ceilingEntry(key);
     }
 
     @Override
-    public K floorKey(K key) {
+    @CheckForNull
+    public K floorKey(@ParametricNullness K key) {
       return forward().ceilingKey(key);
     }
 
     @Override
-    public Entry<K, V> ceilingEntry(K key) {
+    @CheckForNull
+    public Entry<K, V> ceilingEntry(@ParametricNullness K key) {
       return forward().floorEntry(key);
     }
 
     @Override
-    public K ceilingKey(K key) {
+    @CheckForNull
+    public K ceilingKey(@ParametricNullness K key) {
       return forward().floorKey(key);
     }
 
     @Override
-    public Entry<K, V> higherEntry(K key) {
+    @CheckForNull
+    public Entry<K, V> higherEntry(@ParametricNullness K key) {
       return forward().lowerEntry(key);
     }
 
     @Override
-    public K higherKey(K key) {
+    @CheckForNull
+    public K higherKey(@ParametricNullness K key) {
       return forward().lowerKey(key);
     }
 
     @Override
+    @CheckForNull
     public Entry<K, V> firstEntry() {
       return forward().lastEntry();
     }
 
     @Override
+    @CheckForNull
     public Entry<K, V> lastEntry() {
       return forward().firstEntry();
     }
 
     @Override
+    @CheckForNull
     public Entry<K, V> pollFirstEntry() {
       return forward().pollLastEntry();
     }
 
     @Override
+    @CheckForNull
     public Entry<K, V> pollLastEntry() {
       return forward().pollFirstEntry();
     }
@@ -4099,7 +4524,7 @@ public NavigableMap<K, V> descendingMap() {
       return forward();
     }
 
-    private transient @Nullable Set<Entry<K, V>> entrySet;
+    @CheckForNull private transient Set<Entry<K, V>> entrySet;
 
     @Override
     public Set<Entry<K, V>> entrySet() {
@@ -4130,7 +4555,7 @@ public Set<K> keySet() {
       return navigableKeySet();
     }
 
-    private transient @Nullable NavigableSet<K> navigableKeySet;
+    @CheckForNull private transient NavigableSet<K> navigableKeySet;
 
     @Override
     public NavigableSet<K> navigableKeySet() {
@@ -4145,32 +4570,35 @@ public NavigableSet<K> descendingKeySet() {
 
     @Override
     public NavigableMap<K, V> subMap(
-        K fromKey, boolean fromInclusive, K toKey, boolean toInclusive) {
+        @ParametricNullness K fromKey,
+        boolean fromInclusive,
+        @ParametricNullness K toKey,
+        boolean toInclusive) {
       return forward().subMap(toKey, toInclusive, fromKey, fromInclusive).descendingMap();
     }
 
     @Override
-    public SortedMap<K, V> subMap(K fromKey, K toKey) {
+    public SortedMap<K, V> subMap(@ParametricNullness K fromKey, @ParametricNullness K toKey) {
       return subMap(fromKey, true, toKey, false);
     }
 
     @Override
-    public NavigableMap<K, V> headMap(K toKey, boolean inclusive) {
+    public NavigableMap<K, V> headMap(@ParametricNullness K toKey, boolean inclusive) {
       return forward().tailMap(toKey, inclusive).descendingMap();
     }
 
     @Override
-    public SortedMap<K, V> headMap(K toKey) {
+    public SortedMap<K, V> headMap(@ParametricNullness K toKey) {
       return headMap(toKey, false);
     }
 
     @Override
-    public NavigableMap<K, V> tailMap(K fromKey, boolean inclusive) {
+    public NavigableMap<K, V> tailMap(@ParametricNullness K fromKey, boolean inclusive) {
       return forward().headMap(fromKey, inclusive).descendingMap();
     }
 
     @Override
-    public SortedMap<K, V> tailMap(K fromKey) {
+    public SortedMap<K, V> tailMap(@ParametricNullness K fromKey) {
       return tailMap(fromKey, true);
     }
 
@@ -4192,7 +4620,7 @@ static <E> ImmutableMap<E, Integer> indexMap(Collection<E> list) {
     for (E e : list) {
       builder.put(e, i++);
     }
-    return builder.build();
+    return builder.buildOrThrow();
   }
 
   /**
@@ -4213,8 +4641,8 @@ static <E> ImmutableMap<E, Integer> indexMap(Collection<E> list) {
    */
   @Beta
   @GwtIncompatible // NavigableMap
-  public static <K extends Comparable<? super K>, V> NavigableMap<K, V> subMap(
-      NavigableMap<K, V> map, Range<K> range) {
+  public static <K extends Comparable<? super K>, V extends @Nullable Object>
+      NavigableMap<K, V> subMap(NavigableMap<K, V> map, Range<K> range) {
     if (map.comparator() != null
         && map.comparator() != Ordering.natural()
         && range.hasLowerBound()
diff --git a/guava/src/com/google/common/collect/MinMaxPriorityQueue.java b/guava/src/com/google/common/collect/MinMaxPriorityQueue.java
index 32cebefd4d99..181b3fbb50b3 100644
--- a/guava/src/com/google/common/collect/MinMaxPriorityQueue.java
+++ b/guava/src/com/google/common/collect/MinMaxPriorityQueue.java
@@ -21,6 +21,7 @@
 import static com.google.common.base.Preconditions.checkPositionIndex;
 import static com.google.common.base.Preconditions.checkState;
 import static com.google.common.collect.CollectPreconditions.checkRemove;
+import static java.util.Objects.requireNonNull;
 
 import com.google.common.annotations.Beta;
 import com.google.common.annotations.GwtCompatible;
@@ -41,6 +42,7 @@
 import java.util.NoSuchElementException;
 import java.util.PriorityQueue;
 import java.util.Queue;
+import javax.annotation.CheckForNull;
 import org.checkerframework.checker.nullness.qual.Nullable;
 
 /**
@@ -98,6 +100,7 @@
  */
 @Beta
 @GwtCompatible
+@ElementTypesAreNonnullByDefault
 public final class MinMaxPriorityQueue<E> extends AbstractQueue<E> {
 
   /**
@@ -121,8 +124,14 @@ public static <E extends Comparable<E>> MinMaxPriorityQueue<E> create(
    * Creates and returns a new builder, configured to build {@code MinMaxPriorityQueue} instances
    * that use {@code comparator} to determine the least and greatest elements.
    */
+  /*
+   * TODO(cpovirk): Change to Comparator<? super B> to permit Comparator<@Nullable ...> and
+   * Comparator<SupertypeOfB>? What we have here matches the immutable collections, but those also
+   * expose a public Builder constructor that accepts "? super." So maybe we should do *that*
+   * instead.
+   */
   public static <B> Builder<B> orderedBy(Comparator<B> comparator) {
-    return new Builder<B>(comparator);
+    return new Builder<>(comparator);
   }
 
   /**
@@ -207,7 +216,7 @@ public <T extends B> MinMaxPriorityQueue<T> create() {
      */
     public <T extends B> MinMaxPriorityQueue<T> create(Iterable<? extends T> initialContents) {
       MinMaxPriorityQueue<T> queue =
-          new MinMaxPriorityQueue<T>(
+          new MinMaxPriorityQueue<>(
               this, initialQueueSize(expectedSize, maximumSize, initialContents));
       for (T element : initialContents) {
         queue.offer(element);
@@ -224,7 +233,7 @@ private <T extends B> Ordering<T> ordering() {
   private final Heap minHeap;
   private final Heap maxHeap;
   @VisibleForTesting final int maximumSize;
-  private Object[] queue;
+  private @Nullable Object[] queue;
   private int size;
   private int modCount;
 
@@ -292,16 +301,22 @@ public boolean offer(E element) {
 
   @CanIgnoreReturnValue
   @Override
+  @CheckForNull
   public E poll() {
     return isEmpty() ? null : removeAndGet(0);
   }
 
   @SuppressWarnings("unchecked") // we must carefully only allow Es to get in
   E elementData(int index) {
-    return (E) queue[index];
+    /*
+     * requireNonNull is safe as long as we're careful to call this method only with populated
+     * indexes.
+     */
+    return (E) requireNonNull(queue[index]);
   }
 
   @Override
+  @CheckForNull
   public E peek() {
     return isEmpty() ? null : elementData(0);
   }
@@ -325,6 +340,7 @@ private int getMaxElementIndex() {
    * empty.
    */
   @CanIgnoreReturnValue
+  @CheckForNull
   public E pollFirst() {
     return poll();
   }
@@ -343,6 +359,7 @@ public E removeFirst() {
    * Retrieves, but does not remove, the least element of this queue, or returns {@code null} if the
    * queue is empty.
    */
+  @CheckForNull
   public E peekFirst() {
     return peek();
   }
@@ -352,6 +369,7 @@ public E peekFirst() {
    * empty.
    */
   @CanIgnoreReturnValue
+  @CheckForNull
   public E pollLast() {
     return isEmpty() ? null : removeAndGet(getMaxElementIndex());
   }
@@ -373,6 +391,7 @@ public E removeLast() {
    * Retrieves, but does not remove, the greatest element of this queue, or returns {@code null} if
    * the queue is empty.
    */
+  @CheckForNull
   public E peekLast() {
     return isEmpty() ? null : elementData(getMaxElementIndex());
   }
@@ -392,6 +411,7 @@ public E peekLast() {
    */
   @VisibleForTesting
   @CanIgnoreReturnValue
+  @CheckForNull
   MoveDesc<E> removeAt(int index) {
     checkPositionIndex(index, size);
     modCount++;
@@ -416,17 +436,18 @@ MoveDesc<E> removeAt(int index) {
       // Last element is moved to before index, swapped with trickled element.
       if (changes == null) {
         // The trickled element is still after index.
-        return new MoveDesc<E>(actualLastElement, toTrickle);
+        return new MoveDesc<>(actualLastElement, toTrickle);
       } else {
         // The trickled element is back before index, but the replaced element
         // has now been moved after index.
-        return new MoveDesc<E>(actualLastElement, changes.replaced);
+        return new MoveDesc<>(actualLastElement, changes.replaced);
       }
     }
     // Trickled element was after index to begin with, no adjustment needed.
     return changes;
   }
 
+  @CheckForNull
   private MoveDesc<E> fillHole(int index, E toTrickle) {
     Heap heap = heapForIndex(index);
     // We consider elementData(index) a "hole", and we want to fill it
@@ -504,7 +525,7 @@ boolean isIntact() {
   @WeakOuter
   private class Heap {
     final Ordering<E> ordering;
-    @Weak @Nullable Heap otherHeap;
+    @Weak Heap otherHeap; // always initialized immediately after construction
 
     Heap(Ordering<E> ordering) {
       this.ordering = ordering;
@@ -518,6 +539,7 @@ int compareElements(int a, int b) {
      * Tries to move {@code toTrickle} from a min to a max level and bubble up there. If it moved
      * before {@code removeIndex} this method returns a pair as described in {@link #removeAt}.
      */
+    @CheckForNull
     MoveDesc<E> tryCrossOverAndBubbleUp(int removeIndex, int vacated, E toTrickle) {
       int crossOver = crossOver(vacated, toTrickle);
       if (crossOver == vacated) {
@@ -538,7 +560,7 @@ MoveDesc<E> tryCrossOverAndBubbleUp(int removeIndex, int vacated, E toTrickle) {
       }
       // bubble it up the opposite heap
       if (otherHeap.bubbleUpAlternatingLevels(crossOver, toTrickle) < removeIndex) {
-        return new MoveDesc<E>(toTrickle, parent);
+        return new MoveDesc<>(toTrickle, parent);
       } else {
         return null;
       }
@@ -751,9 +773,9 @@ private class QueueIterator implements Iterator<E> {
     private int expectedModCount = modCount;
     // The same element is not allowed in both forgetMeNot and skipMe, but duplicates are allowed in
     // either of them, up to the same multiplicity as the queue.
-    private @Nullable Queue<E> forgetMeNot;
-    private @Nullable List<E> skipMe;
-    private @Nullable E lastFromForgetMeNot;
+    @CheckForNull private Queue<E> forgetMeNot;
+    @CheckForNull private List<E> skipMe;
+    @CheckForNull private E lastFromForgetMeNot;
     private boolean canRemove;
 
     @Override
@@ -791,9 +813,10 @@ public void remove() {
       if (cursor < size()) {
         MoveDesc<E> moved = removeAt(cursor);
         if (moved != null) {
-          if (forgetMeNot == null) {
-            forgetMeNot = new ArrayDeque<E>();
-            skipMe = new ArrayList<E>(3);
+          // Either both are null or neither is, but we check both to satisfy the nullness checker.
+          if (forgetMeNot == null || skipMe == null) {
+            forgetMeNot = new ArrayDeque<>();
+            skipMe = new ArrayList<>(3);
           }
           if (!foundAndRemovedExactReference(skipMe, moved.toTrickle)) {
             forgetMeNot.add(moved.toTrickle);
@@ -805,7 +828,7 @@ public void remove() {
         cursor--;
         nextCursor--;
       } else { // we must have set lastFromForgetMeNot in next()
-        checkState(removeExact(lastFromForgetMeNot));
+        checkState(removeExact(requireNonNull(lastFromForgetMeNot)));
         lastFromForgetMeNot = null;
       }
     }
diff --git a/guava/src/com/google/common/collect/MoreCollectors.java b/guava/src/com/google/common/collect/MoreCollectors.java
index f447ebeb3b54..5a84a4628e3b 100644
--- a/guava/src/com/google/common/collect/MoreCollectors.java
+++ b/guava/src/com/google/common/collect/MoreCollectors.java
@@ -17,6 +17,7 @@
 package com.google.common.collect;
 
 import static com.google.common.base.Preconditions.checkNotNull;
+import static java.util.Collections.emptyList;
 
 import com.google.common.annotations.GwtCompatible;
 import java.util.ArrayList;
@@ -34,6 +35,7 @@
  * @since 21.0
  */
 @GwtCompatible
+@ElementTypesAreNonnullByDefault
 public final class MoreCollectors {
 
   /*
@@ -49,10 +51,12 @@ public final class MoreCollectors {
           Collector.Characteristics.UNORDERED);
 
   /**
-   * A collector that converts a stream of zero or one elements to an {@code Optional}. The returned
-   * collector throws an {@code IllegalArgumentException} if the stream consists of two or more
-   * elements, and a {@code NullPointerException} if the stream consists of exactly one element,
-   * which is null.
+   * A collector that converts a stream of zero or one elements to an {@code Optional}.
+   *
+   * @throws IllegalArgumentException if the stream consists of two or more elements.
+   * @throws NullPointerException if any element in the stream is {@code null}.
+   * @return {@code Optional.of(onlyElement)} if the stream has exactly one element (must not be
+   *     {@code null}) and returns {@code Optional.empty()} if it has none.
    */
   @SuppressWarnings("unchecked")
   public static <T> Collector<T, ?, Optional<T>> toOptional() {
@@ -61,8 +65,8 @@ public final class MoreCollectors {
 
   private static final Object NULL_PLACEHOLDER = new Object();
 
-  private static final Collector<Object, ?, Object> ONLY_ELEMENT =
-      Collector.of(
+  private static final Collector<@Nullable Object, ?, @Nullable Object> ONLY_ELEMENT =
+      Collector.<@Nullable Object, ToOptionalState, @Nullable Object>of(
           ToOptionalState::new,
           (state, o) -> state.add((o == null) ? NULL_PLACEHOLDER : o),
           ToOptionalState::combine,
@@ -78,7 +82,7 @@ public final class MoreCollectors {
    * more elements, and a {@code NoSuchElementException} if the stream is empty.
    */
   @SuppressWarnings("unchecked")
-  public static <T> Collector<T, ?, T> onlyElement() {
+  public static <T extends @Nullable Object> Collector<T, ?, T> onlyElement() {
     return (Collector) ONLY_ELEMENT;
   }
 
@@ -90,11 +94,11 @@ private static final class ToOptionalState {
     static final int MAX_EXTRAS = 4;
 
     @Nullable Object element;
-    @Nullable List<Object> extras;
+    List<Object> extras;
 
     ToOptionalState() {
       element = null;
-      extras = null;
+      extras = emptyList();
     }
 
     IllegalArgumentException multiples(boolean overflow) {
@@ -114,7 +118,8 @@ void add(Object o) {
       checkNotNull(o);
       if (element == null) {
         this.element = o;
-      } else if (extras == null) {
+      } else if (extras.isEmpty()) {
+        // Replace immutable empty list with mutable list.
         extras = new ArrayList<>(MAX_EXTRAS);
         extras.add(o);
       } else if (extras.size() < MAX_EXTRAS) {
@@ -130,13 +135,12 @@ ToOptionalState combine(ToOptionalState other) {
       } else if (other.element == null) {
         return this;
       } else {
-        if (extras == null) {
+        if (extras.isEmpty()) {
+          // Replace immutable empty list with mutable list.
           extras = new ArrayList<>();
         }
         extras.add(other.element);
-        if (other.extras != null) {
-          this.extras.addAll(other.extras);
-        }
+        extras.addAll(other.extras);
         if (extras.size() > MAX_EXTRAS) {
           extras.subList(MAX_EXTRAS, extras.size()).clear();
           throw multiples(true);
@@ -146,7 +150,7 @@ ToOptionalState combine(ToOptionalState other) {
     }
 
     Optional<Object> getOptional() {
-      if (extras == null) {
+      if (extras.isEmpty()) {
         return Optional.ofNullable(element);
       } else {
         throw multiples(false);
@@ -156,7 +160,7 @@ Optional<Object> getOptional() {
     Object getElement() {
       if (element == null) {
         throw new NoSuchElementException();
-      } else if (extras == null) {
+      } else if (extras.isEmpty()) {
         return element;
       } else {
         throw multiples(false);
diff --git a/guava/src/com/google/common/collect/Multimap.java b/guava/src/com/google/common/collect/Multimap.java
index 5dde38d3c711..cb30feb1e05b 100644
--- a/guava/src/com/google/common/collect/Multimap.java
+++ b/guava/src/com/google/common/collect/Multimap.java
@@ -28,6 +28,7 @@
 import java.util.Map.Entry;
 import java.util.Set;
 import java.util.function.BiConsumer;
+import javax.annotation.CheckForNull;
 import org.checkerframework.checker.nullness.qual.Nullable;
 import org.checkerframework.dataflow.qual.Pure;
 import org.checkerframework.framework.qual.AnnotatedFor;
@@ -155,8 +156,7 @@
  * {@link UnsupportedOperationException}.
  *
  * <p>See the Guava User Guide article on <a href=
- * "https://github.com/google/guava/wiki/NewCollectionTypesExplained#multimap"> {@code
- * Multimap}</a>.
+ * "https://github.com/google/guava/wiki/NewCollectionTypesExplained#multimap">{@code Multimap}</a>.
  *
  * @author Jared Levy
  * @since 2.0
@@ -164,7 +164,8 @@
 @DoNotMock("Use ImmutableMultimap, HashMultimap, or another implementation")
 @GwtCompatible
 @AnnotatedFor({"nullness"})
-public interface Multimap<K, V> {
+@ElementTypesAreNonnullByDefault
+public interface Multimap<K extends @Nullable Object, V extends @Nullable Object> {
   // Query Operations
 
   /**
@@ -188,14 +189,14 @@ public interface Multimap<K, V> {
    * key}.
    */
   @Pure
-  boolean containsKey(@CompatibleWith("K") @Nullable Object key);
+  boolean containsKey(@CompatibleWith("K") @CheckForNull Object key);
 
   /**
    * Returns {@code true} if this multimap contains at least one key-value pair with the value
    * {@code value}.
    */
   @Pure
-  boolean containsValue(@CompatibleWith("V") @Nullable Object value);
+  boolean containsValue(@CompatibleWith("V") @CheckForNull Object value);
 
   /**
    * Returns {@code true} if this multimap contains at least one key-value pair with the key {@code
@@ -203,7 +204,8 @@ public interface Multimap<K, V> {
    */
   @Pure
   boolean containsEntry(
-      @CompatibleWith("K") @Nullable Object key, @CompatibleWith("V") @Nullable Object value);
+      @CompatibleWith("K") @CheckForNull Object key,
+      @CompatibleWith("V") @CheckForNull Object value);
 
   // Modification Operations
 
@@ -218,7 +220,7 @@ boolean containsEntry(
    *     multimap already contained the key-value pair and doesn't allow duplicates
    */
   @CanIgnoreReturnValue
-  boolean put(@Nullable K key, @Nullable V value);
+  boolean put(@ParametricNullness K key, @ParametricNullness V value);
 
   /**
    * Removes a single key-value pair with the key {@code key} and the value {@code value} from this
@@ -229,7 +231,8 @@ boolean containsEntry(
    */
   @CanIgnoreReturnValue
   boolean remove(
-      @CompatibleWith("K") @Nullable Object key, @CompatibleWith("V") @Nullable Object value);
+      @CompatibleWith("K") @CheckForNull Object key,
+      @CompatibleWith("V") @CheckForNull Object value);
 
   // Bulk Operations
 
@@ -248,7 +251,7 @@ boolean remove(
    * @return {@code true} if the multimap changed
    */
   @CanIgnoreReturnValue
-  boolean putAll(@Nullable K key, Iterable<? extends V> values);
+  boolean putAll(@ParametricNullness K key, Iterable<? extends V> values);
 
   /**
    * Stores all key-value pairs of {@code multimap} in this multimap, in the order returned by
@@ -269,7 +272,7 @@ boolean remove(
    *     no effect on the multimap.
    */
   @CanIgnoreReturnValue
-  Collection<V> replaceValues(@Nullable K key, Iterable<? extends V> values);
+  Collection<V> replaceValues(@ParametricNullness K key, Iterable<? extends V> values);
 
   /**
    * Removes all values associated with the key {@code key}.
@@ -281,7 +284,7 @@ boolean remove(
    *     modifiable, but updating it will have no effect on the multimap.
    */
   @CanIgnoreReturnValue
-  Collection<V> removeAll(@CompatibleWith("K") @Nullable Object key);
+  Collection<V> removeAll(@CompatibleWith("K") @CheckForNull Object key);
 
   /** Removes all key-value pairs from the multimap, leaving it {@linkplain #isEmpty empty}. */
   void clear();
@@ -295,7 +298,7 @@ boolean remove(
    *
    * <p>Changes to the returned collection will update the underlying multimap, and vice versa.
    */
-  Collection<V> get(@Nullable K key);
+  Collection<V> get(@ParametricNullness K key);
 
   /**
    * Returns a view collection of all <i>distinct</i> keys contained in this multimap. Note that the
@@ -378,7 +381,7 @@ default void forEach(BiConsumer<? super K, ? super V> action) {
    */
   @Pure
   @Override
-  boolean equals(@Nullable Object obj);
+  boolean equals(@CheckForNull Object obj);
 
   /**
    * Returns the hash code for this multimap.
diff --git a/guava/src/com/google/common/collect/MultimapBuilder.java b/guava/src/com/google/common/collect/MultimapBuilder.java
index 161c29d170ee..3d6278aaec9d 100644
--- a/guava/src/com/google/common/collect/MultimapBuilder.java
+++ b/guava/src/com/google/common/collect/MultimapBuilder.java
@@ -34,6 +34,7 @@
 import java.util.SortedSet;
 import java.util.TreeMap;
 import java.util.TreeSet;
+import org.checkerframework.checker.nullness.qual.Nullable;
 
 /**
  * A builder for a multimap implementation that allows customization of the backing map and value
@@ -61,7 +62,8 @@
  * @since 16.0
  */
 @GwtCompatible
-public abstract class MultimapBuilder<K0, V0> {
+@ElementTypesAreNonnullByDefault
+public abstract class MultimapBuilder<K0 extends @Nullable Object, V0 extends @Nullable Object> {
   /*
    * Leaving K and V as upper bounds rather than the actual key and value types allows type
    * parameters to be left implicit more often. CacheBuilder uses the same technique.
@@ -72,7 +74,7 @@ private MultimapBuilder() {}
   private static final int DEFAULT_EXPECTED_KEYS = 8;
 
   /** Uses a hash table to map keys to value collections. */
-  public static MultimapBuilderWithKeys<Object> hashKeys() {
+  public static MultimapBuilderWithKeys<@Nullable Object> hashKeys() {
     return hashKeys(DEFAULT_EXPECTED_KEYS);
   }
 
@@ -82,11 +84,11 @@ public static MultimapBuilderWithKeys<Object> hashKeys() {
    *
    * @throws IllegalArgumentException if {@code expectedKeys < 0}
    */
-  public static MultimapBuilderWithKeys<Object> hashKeys(final int expectedKeys) {
+  public static MultimapBuilderWithKeys<@Nullable Object> hashKeys(int expectedKeys) {
     checkNonnegative(expectedKeys, "expectedKeys");
-    return new MultimapBuilderWithKeys<Object>() {
+    return new MultimapBuilderWithKeys<@Nullable Object>() {
       @Override
-      <K, V> Map<K, Collection<V>> createMap() {
+      <K extends @Nullable Object, V extends @Nullable Object> Map<K, Collection<V>> createMap() {
         return Platform.newHashMapWithExpectedSize(expectedKeys);
       }
     };
@@ -100,7 +102,7 @@ <K, V> Map<K, Collection<V>> createMap() {
    * multimap, save that if all values associated with a key are removed and then the key is added
    * back into the multimap, that key will come last in the key iteration order.
    */
-  public static MultimapBuilderWithKeys<Object> linkedHashKeys() {
+  public static MultimapBuilderWithKeys<@Nullable Object> linkedHashKeys() {
     return linkedHashKeys(DEFAULT_EXPECTED_KEYS);
   }
 
@@ -113,11 +115,11 @@ public static MultimapBuilderWithKeys<Object> linkedHashKeys() {
    * multimap, save that if all values associated with a key are removed and then the key is added
    * back into the multimap, that key will come last in the key iteration order.
    */
-  public static MultimapBuilderWithKeys<Object> linkedHashKeys(final int expectedKeys) {
+  public static MultimapBuilderWithKeys<@Nullable Object> linkedHashKeys(int expectedKeys) {
     checkNonnegative(expectedKeys, "expectedKeys");
-    return new MultimapBuilderWithKeys<Object>() {
+    return new MultimapBuilderWithKeys<@Nullable Object>() {
       @Override
-      <K, V> Map<K, Collection<V>> createMap() {
+      <K extends @Nullable Object, V extends @Nullable Object> Map<K, Collection<V>> createMap() {
         return Platform.newLinkedHashMapWithExpectedSize(expectedKeys);
       }
     };
@@ -151,11 +153,12 @@ public static MultimapBuilderWithKeys<Comparable> treeKeys() {
    * <p>Multimaps generated by the resulting builder will not be serializable if {@code comparator}
    * is not serializable.
    */
-  public static <K0> MultimapBuilderWithKeys<K0> treeKeys(final Comparator<K0> comparator) {
+  public static <K0 extends @Nullable Object> MultimapBuilderWithKeys<K0> treeKeys(
+      Comparator<K0> comparator) {
     checkNotNull(comparator);
     return new MultimapBuilderWithKeys<K0>() {
       @Override
-      <K extends K0, V> Map<K, Collection<V>> createMap() {
+      <K extends K0, V extends @Nullable Object> Map<K, Collection<V>> createMap() {
         return new TreeMap<>(comparator);
       }
     };
@@ -166,13 +169,12 @@ <K extends K0, V> Map<K, Collection<V>> createMap() {
    *
    * @since 16.0
    */
-  public static <K0 extends Enum<K0>> MultimapBuilderWithKeys<K0> enumKeys(
-      final Class<K0> keyClass) {
+  public static <K0 extends Enum<K0>> MultimapBuilderWithKeys<K0> enumKeys(Class<K0> keyClass) {
     checkNotNull(keyClass);
     return new MultimapBuilderWithKeys<K0>() {
       @SuppressWarnings("unchecked")
       @Override
-      <K extends K0, V> Map<K, Collection<V>> createMap() {
+      <K extends K0, V extends @Nullable Object> Map<K, Collection<V>> createMap() {
         // K must actually be K0, since enums are effectively final
         // (their subclasses are inaccessible)
         return (Map<K, Collection<V>>) new EnumMap<K0, Collection<V>>(keyClass);
@@ -180,7 +182,8 @@ <K extends K0, V> Map<K, Collection<V>> createMap() {
     };
   }
 
-  private static final class ArrayListSupplier<V> implements Supplier<List<V>>, Serializable {
+  private static final class ArrayListSupplier<V extends @Nullable Object>
+      implements Supplier<List<V>>, Serializable {
     private final int expectedValuesPerKey;
 
     ArrayListSupplier(int expectedValuesPerKey) {
@@ -189,14 +192,14 @@ private static final class ArrayListSupplier<V> implements Supplier<List<V>>, Se
 
     @Override
     public List<V> get() {
-      return new ArrayList<V>(expectedValuesPerKey);
+      return new ArrayList<>(expectedValuesPerKey);
     }
   }
 
-  private enum LinkedListSupplier implements Supplier<List<Object>> {
+  private enum LinkedListSupplier implements Supplier<List<?>> {
     INSTANCE;
 
-    public static <V> Supplier<List<V>> instance() {
+    public static <V extends @Nullable Object> Supplier<List<V>> instance() {
       // Each call generates a fresh LinkedList, which can serve as a List<V> for any V.
       @SuppressWarnings({"rawtypes", "unchecked"})
       Supplier<List<V>> result = (Supplier) INSTANCE;
@@ -204,12 +207,13 @@ public static <V> Supplier<List<V>> instance() {
     }
 
     @Override
-    public List<Object> get() {
+    public List<?> get() {
       return new LinkedList<>();
     }
   }
 
-  private static final class HashSetSupplier<V> implements Supplier<Set<V>>, Serializable {
+  private static final class HashSetSupplier<V extends @Nullable Object>
+      implements Supplier<Set<V>>, Serializable {
     private final int expectedValuesPerKey;
 
     HashSetSupplier(int expectedValuesPerKey) {
@@ -222,7 +226,8 @@ public Set<V> get() {
     }
   }
 
-  private static final class LinkedHashSetSupplier<V> implements Supplier<Set<V>>, Serializable {
+  private static final class LinkedHashSetSupplier<V extends @Nullable Object>
+      implements Supplier<Set<V>>, Serializable {
     private final int expectedValuesPerKey;
 
     LinkedHashSetSupplier(int expectedValuesPerKey) {
@@ -235,7 +240,8 @@ public Set<V> get() {
     }
   }
 
-  private static final class TreeSetSupplier<V> implements Supplier<SortedSet<V>>, Serializable {
+  private static final class TreeSetSupplier<V extends @Nullable Object>
+      implements Supplier<SortedSet<V>>, Serializable {
     private final Comparator<? super V> comparator;
 
     TreeSetSupplier(Comparator<? super V> comparator) {
@@ -244,7 +250,7 @@ private static final class TreeSetSupplier<V> implements Supplier<SortedSet<V>>,
 
     @Override
     public SortedSet<V> get() {
-      return new TreeSet<V>(comparator);
+      return new TreeSet<>(comparator);
     }
   }
 
@@ -269,16 +275,16 @@ public Set<V> get() {
    * @param <K0> The upper bound on the key type of the generated multimap.
    * @since 16.0
    */
-  public abstract static class MultimapBuilderWithKeys<K0> {
+  public abstract static class MultimapBuilderWithKeys<K0 extends @Nullable Object> {
 
     private static final int DEFAULT_EXPECTED_VALUES_PER_KEY = 2;
 
     MultimapBuilderWithKeys() {}
 
-    abstract <K extends K0, V> Map<K, Collection<V>> createMap();
+    abstract <K extends K0, V extends @Nullable Object> Map<K, Collection<V>> createMap();
 
     /** Uses an {@link ArrayList} to store value collections. */
-    public ListMultimapBuilder<K0, Object> arrayListValues() {
+    public ListMultimapBuilder<K0, @Nullable Object> arrayListValues() {
       return arrayListValues(DEFAULT_EXPECTED_VALUES_PER_KEY);
     }
 
@@ -288,11 +294,11 @@ public ListMultimapBuilder<K0, Object> arrayListValues() {
      *
      * @throws IllegalArgumentException if {@code expectedValuesPerKey < 0}
      */
-    public ListMultimapBuilder<K0, Object> arrayListValues(final int expectedValuesPerKey) {
+    public ListMultimapBuilder<K0, @Nullable Object> arrayListValues(int expectedValuesPerKey) {
       checkNonnegative(expectedValuesPerKey, "expectedValuesPerKey");
-      return new ListMultimapBuilder<K0, Object>() {
+      return new ListMultimapBuilder<K0, @Nullable Object>() {
         @Override
-        public <K extends K0, V> ListMultimap<K, V> build() {
+        public <K extends K0, V extends @Nullable Object> ListMultimap<K, V> build() {
           return Multimaps.newListMultimap(
               MultimapBuilderWithKeys.this.<K, V>createMap(),
               new ArrayListSupplier<V>(expectedValuesPerKey));
@@ -301,10 +307,10 @@ public <K extends K0, V> ListMultimap<K, V> build() {
     }
 
     /** Uses a {@link LinkedList} to store value collections. */
-    public ListMultimapBuilder<K0, Object> linkedListValues() {
-      return new ListMultimapBuilder<K0, Object>() {
+    public ListMultimapBuilder<K0, @Nullable Object> linkedListValues() {
+      return new ListMultimapBuilder<K0, @Nullable Object>() {
         @Override
-        public <K extends K0, V> ListMultimap<K, V> build() {
+        public <K extends K0, V extends @Nullable Object> ListMultimap<K, V> build() {
           return Multimaps.newListMultimap(
               MultimapBuilderWithKeys.this.<K, V>createMap(), LinkedListSupplier.<V>instance());
         }
@@ -312,7 +318,7 @@ public <K extends K0, V> ListMultimap<K, V> build() {
     }
 
     /** Uses a hash-based {@code Set} to store value collections. */
-    public SetMultimapBuilder<K0, Object> hashSetValues() {
+    public SetMultimapBuilder<K0, @Nullable Object> hashSetValues() {
       return hashSetValues(DEFAULT_EXPECTED_VALUES_PER_KEY);
     }
 
@@ -322,11 +328,11 @@ public SetMultimapBuilder<K0, Object> hashSetValues() {
      *
      * @throws IllegalArgumentException if {@code expectedValuesPerKey < 0}
      */
-    public SetMultimapBuilder<K0, Object> hashSetValues(final int expectedValuesPerKey) {
+    public SetMultimapBuilder<K0, @Nullable Object> hashSetValues(int expectedValuesPerKey) {
       checkNonnegative(expectedValuesPerKey, "expectedValuesPerKey");
-      return new SetMultimapBuilder<K0, Object>() {
+      return new SetMultimapBuilder<K0, @Nullable Object>() {
         @Override
-        public <K extends K0, V> SetMultimap<K, V> build() {
+        public <K extends K0, V extends @Nullable Object> SetMultimap<K, V> build() {
           return Multimaps.newSetMultimap(
               MultimapBuilderWithKeys.this.<K, V>createMap(),
               new HashSetSupplier<V>(expectedValuesPerKey));
@@ -335,7 +341,7 @@ public <K extends K0, V> SetMultimap<K, V> build() {
     }
 
     /** Uses an insertion-ordered hash-based {@code Set} to store value collections. */
-    public SetMultimapBuilder<K0, Object> linkedHashSetValues() {
+    public SetMultimapBuilder<K0, @Nullable Object> linkedHashSetValues() {
       return linkedHashSetValues(DEFAULT_EXPECTED_VALUES_PER_KEY);
     }
 
@@ -345,11 +351,11 @@ public SetMultimapBuilder<K0, Object> linkedHashSetValues() {
      *
      * @throws IllegalArgumentException if {@code expectedValuesPerKey < 0}
      */
-    public SetMultimapBuilder<K0, Object> linkedHashSetValues(final int expectedValuesPerKey) {
+    public SetMultimapBuilder<K0, @Nullable Object> linkedHashSetValues(int expectedValuesPerKey) {
       checkNonnegative(expectedValuesPerKey, "expectedValuesPerKey");
-      return new SetMultimapBuilder<K0, Object>() {
+      return new SetMultimapBuilder<K0, @Nullable Object>() {
         @Override
-        public <K extends K0, V> SetMultimap<K, V> build() {
+        public <K extends K0, V extends @Nullable Object> SetMultimap<K, V> build() {
           return Multimaps.newSetMultimap(
               MultimapBuilderWithKeys.this.<K, V>createMap(),
               new LinkedHashSetSupplier<V>(expectedValuesPerKey));
@@ -369,7 +375,8 @@ public SortedSetMultimapBuilder<K0, Comparable> treeSetValues() {
      * <p>Multimaps generated by the resulting builder will not be serializable if {@code
      * comparator} is not serializable.
      */
-    public <V0> SortedSetMultimapBuilder<K0, V0> treeSetValues(final Comparator<V0> comparator) {
+    public <V0 extends @Nullable Object> SortedSetMultimapBuilder<K0, V0> treeSetValues(
+        Comparator<V0> comparator) {
       checkNotNull(comparator, "comparator");
       return new SortedSetMultimapBuilder<K0, V0>() {
         @Override
@@ -381,8 +388,7 @@ public <K extends K0, V extends V0> SortedSetMultimap<K, V> build() {
     }
 
     /** Uses an {@link EnumSet} to store value collections. */
-    public <V0 extends Enum<V0>> SetMultimapBuilder<K0, V0> enumSetValues(
-        final Class<V0> valueClass) {
+    public <V0 extends Enum<V0>> SetMultimapBuilder<K0, V0> enumSetValues(Class<V0> valueClass) {
       checkNotNull(valueClass, "valueClass");
       return new SetMultimapBuilder<K0, V0>() {
         @Override
@@ -416,7 +422,9 @@ public <K extends K0, V extends V0> Multimap<K, V> build(
    *
    * @since 16.0
    */
-  public abstract static class ListMultimapBuilder<K0, V0> extends MultimapBuilder<K0, V0> {
+  public abstract static class ListMultimapBuilder<
+          K0 extends @Nullable Object, V0 extends @Nullable Object>
+      extends MultimapBuilder<K0, V0> {
     ListMultimapBuilder() {}
 
     @Override
@@ -434,7 +442,9 @@ public <K extends K0, V extends V0> ListMultimap<K, V> build(
    *
    * @since 16.0
    */
-  public abstract static class SetMultimapBuilder<K0, V0> extends MultimapBuilder<K0, V0> {
+  public abstract static class SetMultimapBuilder<
+          K0 extends @Nullable Object, V0 extends @Nullable Object>
+      extends MultimapBuilder<K0, V0> {
     SetMultimapBuilder() {}
 
     @Override
@@ -452,7 +462,9 @@ public <K extends K0, V extends V0> SetMultimap<K, V> build(
    *
    * @since 16.0
    */
-  public abstract static class SortedSetMultimapBuilder<K0, V0> extends SetMultimapBuilder<K0, V0> {
+  public abstract static class SortedSetMultimapBuilder<
+          K0 extends @Nullable Object, V0 extends @Nullable Object>
+      extends SetMultimapBuilder<K0, V0> {
     SortedSetMultimapBuilder() {}
 
     @Override
diff --git a/guava/src/com/google/common/collect/Multimaps.java b/guava/src/com/google/common/collect/Multimaps.java
index a2e37a771b50..88c1aff76042 100644
--- a/guava/src/com/google/common/collect/Multimaps.java
+++ b/guava/src/com/google/common/collect/Multimaps.java
@@ -19,6 +19,8 @@
 import static com.google.common.base.Preconditions.checkNotNull;
 import static com.google.common.collect.CollectPreconditions.checkNonnegative;
 import static com.google.common.collect.CollectPreconditions.checkRemove;
+import static com.google.common.collect.NullnessCasts.uncheckedCastNullableTToT;
+import static java.util.Objects.requireNonNull;
 
 import com.google.common.annotations.Beta;
 import com.google.common.annotations.GwtCompatible;
@@ -54,6 +56,7 @@
 import java.util.function.Consumer;
 import java.util.stream.Collector;
 import java.util.stream.Stream;
+import javax.annotation.CheckForNull;
 import org.checkerframework.checker.nullness.qual.Nullable;
 import org.checkerframework.dataflow.qual.Pure;
 import org.checkerframework.dataflow.qual.SideEffectFree;
@@ -63,7 +66,7 @@
  * Provides static methods acting on or generating a {@code Multimap}.
  *
  * <p>See the Guava User Guide article on <a href=
- * "https://github.com/google/guava/wiki/CollectionUtilitiesExplained#multimaps"> {@code
+ * "https://github.com/google/guava/wiki/CollectionUtilitiesExplained#multimaps">{@code
  * Multimaps}</a>.
  *
  * @author Jared Levy
@@ -74,6 +77,7 @@
  */
 @AnnotatedFor({"nullness"})
 @GwtCompatible(emulated = true)
+@ElementTypesAreNonnullByDefault
 public final class Multimaps {
   private Multimaps() {}
 
@@ -107,12 +111,21 @@ private Multimaps() {}
    * }
    * }</pre>
    *
+   * <p>To collect to an {@link ImmutableMultimap}, use either {@link
+   * ImmutableSetMultimap#toImmutableSetMultimap} or {@link
+   * ImmutableListMultimap#toImmutableListMultimap}.
+   *
    * @since 21.0
    */
-  public static <T, K, V, M extends Multimap<K, V>> Collector<T, ?, M> toMultimap(
-      java.util.function.Function<? super T, ? extends K> keyFunction,
-      java.util.function.Function<? super T, ? extends V> valueFunction,
-      java.util.function.Supplier<M> multimapSupplier) {
+  public static <
+          T extends @Nullable Object,
+          K extends @Nullable Object,
+          V extends @Nullable Object,
+          M extends Multimap<K, V>>
+      Collector<T, ?, M> toMultimap(
+          java.util.function.Function<? super T, ? extends K> keyFunction,
+          java.util.function.Function<? super T, ? extends V> valueFunction,
+          java.util.function.Supplier<M> multimapSupplier) {
     return CollectCollectors.toMultimap(keyFunction, valueFunction, multimapSupplier);
   }
 
@@ -150,10 +163,15 @@ private Multimaps() {}
    * @since 21.0
    */
   @Beta
-  public static <T, K, V, M extends Multimap<K, V>> Collector<T, ?, M> flatteningToMultimap(
-      java.util.function.Function<? super T, ? extends K> keyFunction,
-      java.util.function.Function<? super T, ? extends Stream<? extends V>> valueFunction,
-      java.util.function.Supplier<M> multimapSupplier) {
+  public static <
+          T extends @Nullable Object,
+          K extends @Nullable Object,
+          V extends @Nullable Object,
+          M extends Multimap<K, V>>
+      Collector<T, ?, M> flatteningToMultimap(
+          java.util.function.Function<? super T, ? extends K> keyFunction,
+          java.util.function.Function<? super T, ? extends Stream<? extends V>> valueFunction,
+          java.util.function.Supplier<M> multimapSupplier) {
     return CollectCollectors.flatteningToMultimap(keyFunction, valueFunction, multimapSupplier);
   }
 
@@ -193,12 +211,13 @@ private Multimaps() {}
    *     key
    * @throws IllegalArgumentException if {@code map} is not empty
    */
-  public static <K, V> Multimap<K, V> newMultimap(
+  public static <K extends @Nullable Object, V extends @Nullable Object> Multimap<K, V> newMultimap(
       Map<K, Collection<V>> map, final Supplier<? extends Collection<V>> factory) {
     return new CustomMultimap<>(map, factory);
   }
 
-  private static class CustomMultimap<K, V> extends AbstractMapBasedMultimap<K, V> {
+  private static class CustomMultimap<K extends @Nullable Object, V extends @Nullable Object>
+      extends AbstractMapBasedMultimap<K, V> {
     transient Supplier<? extends Collection<V>> factory;
 
     CustomMultimap(Map<K, Collection<V>> map, Supplier<? extends Collection<V>> factory) {
@@ -222,7 +241,8 @@ protected Collection<V> createCollection() {
     }
 
     @Override
-    <E> Collection<E> unmodifiableCollectionSubclass(Collection<E> collection) {
+    <E extends @Nullable Object> Collection<E> unmodifiableCollectionSubclass(
+        Collection<E> collection) {
       if (collection instanceof NavigableSet) {
         return Sets.unmodifiableNavigableSet((NavigableSet<E>) collection);
       } else if (collection instanceof SortedSet) {
@@ -237,7 +257,7 @@ <E> Collection<E> unmodifiableCollectionSubclass(Collection<E> collection) {
     }
 
     @Override
-    Collection<V> wrapCollection(K key, Collection<V> collection) {
+    Collection<V> wrapCollection(@ParametricNullness K key, Collection<V> collection) {
       if (collection instanceof List) {
         return wrapList(key, (List<V>) collection, null);
       } else if (collection instanceof NavigableSet) {
@@ -305,12 +325,14 @@ private void readObject(ObjectInputStream stream) throws IOException, ClassNotFo
    * @param factory supplier of new, empty lists that will each hold all values for a given key
    * @throws IllegalArgumentException if {@code map} is not empty
    */
-  public static <K, V> ListMultimap<K, V> newListMultimap(
-      Map<K, Collection<V>> map, final Supplier<? extends List<V>> factory) {
+  public static <K extends @Nullable Object, V extends @Nullable Object>
+      ListMultimap<K, V> newListMultimap(
+          Map<K, Collection<V>> map, final Supplier<? extends List<V>> factory) {
     return new CustomListMultimap<>(map, factory);
   }
 
-  private static class CustomListMultimap<K, V> extends AbstractListMultimap<K, V> {
+  private static class CustomListMultimap<K extends @Nullable Object, V extends @Nullable Object>
+      extends AbstractListMultimap<K, V> {
     transient Supplier<? extends List<V>> factory;
 
     CustomListMultimap(Map<K, Collection<V>> map, Supplier<? extends List<V>> factory) {
@@ -383,12 +405,14 @@ private void readObject(ObjectInputStream stream) throws IOException, ClassNotFo
    * @param factory supplier of new, empty sets that will each hold all values for a given key
    * @throws IllegalArgumentException if {@code map} is not empty
    */
-  public static <K, V> SetMultimap<K, V> newSetMultimap(
-      Map<K, Collection<V>> map, final Supplier<? extends Set<V>> factory) {
+  public static <K extends @Nullable Object, V extends @Nullable Object>
+      SetMultimap<K, V> newSetMultimap(
+          Map<K, Collection<V>> map, final Supplier<? extends Set<V>> factory) {
     return new CustomSetMultimap<>(map, factory);
   }
 
-  private static class CustomSetMultimap<K, V> extends AbstractSetMultimap<K, V> {
+  private static class CustomSetMultimap<K extends @Nullable Object, V extends @Nullable Object>
+      extends AbstractSetMultimap<K, V> {
     transient Supplier<? extends Set<V>> factory;
 
     CustomSetMultimap(Map<K, Collection<V>> map, Supplier<? extends Set<V>> factory) {
@@ -412,7 +436,8 @@ protected Set<V> createCollection() {
     }
 
     @Override
-    <E> Collection<E> unmodifiableCollectionSubclass(Collection<E> collection) {
+    <E extends @Nullable Object> Collection<E> unmodifiableCollectionSubclass(
+        Collection<E> collection) {
       if (collection instanceof NavigableSet) {
         return Sets.unmodifiableNavigableSet((NavigableSet<E>) collection);
       } else if (collection instanceof SortedSet) {
@@ -423,7 +448,7 @@ <E> Collection<E> unmodifiableCollectionSubclass(Collection<E> collection) {
     }
 
     @Override
-    Collection<V> wrapCollection(K key, Collection<V> collection) {
+    Collection<V> wrapCollection(@ParametricNullness K key, Collection<V> collection) {
       if (collection instanceof NavigableSet) {
         return new WrappedNavigableSet(key, (NavigableSet<V>) collection, null);
       } else if (collection instanceof SortedSet) {
@@ -483,14 +508,17 @@ private void readObject(ObjectInputStream stream) throws IOException, ClassNotFo
    *     key
    * @throws IllegalArgumentException if {@code map} is not empty
    */
-  public static <K, V> SortedSetMultimap<K, V> newSortedSetMultimap(
-      Map<K, Collection<V>> map, final Supplier<? extends SortedSet<V>> factory) {
+  public static <K extends @Nullable Object, V extends @Nullable Object>
+      SortedSetMultimap<K, V> newSortedSetMultimap(
+          Map<K, Collection<V>> map, final Supplier<? extends SortedSet<V>> factory) {
     return new CustomSortedSetMultimap<>(map, factory);
   }
 
-  private static class CustomSortedSetMultimap<K, V> extends AbstractSortedSetMultimap<K, V> {
+  private static class CustomSortedSetMultimap<
+          K extends @Nullable Object, V extends @Nullable Object>
+      extends AbstractSortedSetMultimap<K, V> {
     transient Supplier<? extends SortedSet<V>> factory;
-    transient Comparator<? super V> valueComparator;
+    @CheckForNull transient Comparator<? super V> valueComparator;
 
     CustomSortedSetMultimap(Map<K, Collection<V>> map, Supplier<? extends SortedSet<V>> factory) {
       super(map);
@@ -514,6 +542,7 @@ protected SortedSet<V> createCollection() {
     }
 
     @Override
+    @CheckForNull
     public Comparator<? super V> valueComparator() {
       return valueComparator;
     }
@@ -552,8 +581,8 @@ private void readObject(ObjectInputStream stream) throws IOException, ClassNotFo
    * @return {@code dest}
    */
   @CanIgnoreReturnValue
-  public static <K, V, M extends Multimap<K, V>> M invertFrom(
-      Multimap<? extends V, ? extends K> source, M dest) {
+  public static <K extends @Nullable Object, V extends @Nullable Object, M extends Multimap<K, V>>
+      M invertFrom(Multimap<? extends V, ? extends K> source, M dest) {
     checkNotNull(dest);
     for (Map.Entry<? extends V, ? extends K> entry : source.entries()) {
       dest.put(entry.getValue(), entry.getKey());
@@ -593,7 +622,8 @@ public static <K, V, M extends Multimap<K, V>> M invertFrom(
    * @param multimap the multimap to be wrapped in a synchronized view
    * @return a synchronized view of the specified multimap
    */
-  public static <K, V> Multimap<K, V> synchronizedMultimap(Multimap<K, V> multimap) {
+  public static <K extends @Nullable Object, V extends @Nullable Object>
+      Multimap<K, V> synchronizedMultimap(Multimap<K, V> multimap) {
     return Synchronized.multimap(multimap, null);
   }
 
@@ -608,7 +638,8 @@ public static <K, V> Multimap<K, V> synchronizedMultimap(Multimap<K, V> multimap
    * @param delegate the multimap for which an unmodifiable view is to be returned
    * @return an unmodifiable view of the specified multimap
    */
-  public static <K, V> Multimap<K, V> unmodifiableMultimap(Multimap<K, V> delegate) {
+  public static <K extends @Nullable Object, V extends @Nullable Object>
+      Multimap<K, V> unmodifiableMultimap(Multimap<K, V> delegate) {
     if (delegate instanceof UnmodifiableMultimap || delegate instanceof ImmutableMultimap) {
       return delegate;
     }
@@ -626,14 +657,14 @@ public static <K, V> Multimap<K, V> unmodifiableMultimap(ImmutableMultimap<K, V>
     return checkNotNull(delegate);
   }
 
-  private static class UnmodifiableMultimap<K, V> extends ForwardingMultimap<K, V>
-      implements Serializable {
+  private static class UnmodifiableMultimap<K extends @Nullable Object, V extends @Nullable Object>
+      extends ForwardingMultimap<K, V> implements Serializable {
     final Multimap<K, V> delegate;
-    @LazyInit transient @Nullable Collection<Entry<K, V>> entries;
-    @LazyInit transient @Nullable Multiset<K> keys;
-    @LazyInit transient @Nullable Set<K> keySet;
-    @LazyInit transient @Nullable Collection<V> values;
-    @LazyInit transient @Nullable Map<K, Collection<V>> map;
+    @LazyInit @CheckForNull transient Collection<Entry<K, V>> entries;
+    @LazyInit @CheckForNull transient Multiset<K> keys;
+    @LazyInit @CheckForNull transient Set<K> keySet;
+    @LazyInit @CheckForNull transient Collection<V> values;
+    @LazyInit @CheckForNull transient Map<K, Collection<V>> map;
 
     UnmodifiableMultimap(final Multimap<K, V> delegate) {
       this.delegate = checkNotNull(delegate);
@@ -684,7 +715,7 @@ public void forEach(BiConsumer<? super K, ? super V> consumer) {
     }
 
     @Override
-    public Collection<V> get(@Nullable K key) {
+    public Collection<V> get(@ParametricNullness K key) {
       return unmodifiableValueCollection(delegate.get(key));
     }
 
@@ -708,12 +739,12 @@ public Set<K> keySet() {
     }
 
     @Override
-    public boolean put(K key, V value) {
+    public boolean put(@ParametricNullness K key, @ParametricNullness V value) {
       throw new UnsupportedOperationException();
     }
 
     @Override
-    public boolean putAll(K key, Iterable<? extends V> values) {
+    public boolean putAll(@ParametricNullness K key, Iterable<? extends V> values) {
       throw new UnsupportedOperationException();
     }
 
@@ -723,17 +754,17 @@ public boolean putAll(Multimap<? extends K, ? extends V> multimap) {
     }
 
     @Override
-    public boolean remove(@Nullable Object key, @Nullable Object value) {
+    public boolean remove(@CheckForNull Object key, @CheckForNull Object value) {
       throw new UnsupportedOperationException();
     }
 
     @Override
-    public Collection<V> removeAll(@Nullable Object key) {
+    public Collection<V> removeAll(@CheckForNull Object key) {
       throw new UnsupportedOperationException();
     }
 
     @Override
-    public Collection<V> replaceValues(K key, Iterable<? extends V> values) {
+    public Collection<V> replaceValues(@ParametricNullness K key, Iterable<? extends V> values) {
       throw new UnsupportedOperationException();
     }
 
@@ -750,8 +781,9 @@ public Collection<V> values() {
     private static final long serialVersionUID = 0;
   }
 
-  private static class UnmodifiableListMultimap<K, V> extends UnmodifiableMultimap<K, V>
-      implements ListMultimap<K, V> {
+  private static class UnmodifiableListMultimap<
+          K extends @Nullable Object, V extends @Nullable Object>
+      extends UnmodifiableMultimap<K, V> implements ListMultimap<K, V> {
     UnmodifiableListMultimap(ListMultimap<K, V> delegate) {
       super(delegate);
     }
@@ -762,25 +794,26 @@ public ListMultimap<K, V> delegate() {
     }
 
     @Override
-    public List<V> get(K key) {
+    public List<V> get(@ParametricNullness K key) {
       return Collections.unmodifiableList(delegate().get(key));
     }
 
     @Override
-    public List<V> removeAll(@Nullable Object key) {
+    public List<V> removeAll(@CheckForNull Object key) {
       throw new UnsupportedOperationException();
     }
 
     @Override
-    public List<V> replaceValues(K key, Iterable<? extends V> values) {
+    public List<V> replaceValues(@ParametricNullness K key, Iterable<? extends V> values) {
       throw new UnsupportedOperationException();
     }
 
     private static final long serialVersionUID = 0;
   }
 
-  private static class UnmodifiableSetMultimap<K, V> extends UnmodifiableMultimap<K, V>
-      implements SetMultimap<K, V> {
+  private static class UnmodifiableSetMultimap<
+          K extends @Nullable Object, V extends @Nullable Object>
+      extends UnmodifiableMultimap<K, V> implements SetMultimap<K, V> {
     UnmodifiableSetMultimap(SetMultimap<K, V> delegate) {
       super(delegate);
     }
@@ -791,7 +824,7 @@ public SetMultimap<K, V> delegate() {
     }
 
     @Override
-    public Set<V> get(@Nullable K key) {
+    public Set<V> get(@ParametricNullness K key) {
       /*
        * Note that this doesn't return a SortedSet when delegate is a
        * SortedSetMultiset, unlike (SortedSet<V>) super.get().
@@ -806,20 +839,21 @@ public Set<Map.Entry<K, V>> entries() {
     }
 
     @Override
-    public Set<V> removeAll(@Nullable Object key) {
+    public Set<V> removeAll(@CheckForNull Object key) {
       throw new UnsupportedOperationException();
     }
 
     @Override
-    public Set<V> replaceValues(K key, Iterable<? extends V> values) {
+    public Set<V> replaceValues(@ParametricNullness K key, Iterable<? extends V> values) {
       throw new UnsupportedOperationException();
     }
 
     private static final long serialVersionUID = 0;
   }
 
-  private static class UnmodifiableSortedSetMultimap<K, V> extends UnmodifiableSetMultimap<K, V>
-      implements SortedSetMultimap<K, V> {
+  private static class UnmodifiableSortedSetMultimap<
+          K extends @Nullable Object, V extends @Nullable Object>
+      extends UnmodifiableSetMultimap<K, V> implements SortedSetMultimap<K, V> {
     UnmodifiableSortedSetMultimap(SortedSetMultimap<K, V> delegate) {
       super(delegate);
     }
@@ -830,22 +864,23 @@ public SortedSetMultimap<K, V> delegate() {
     }
 
     @Override
-    public SortedSet<V> get(K key) {
+    public SortedSet<V> get(@ParametricNullness K key) {
       return Collections.unmodifiableSortedSet(delegate().get(key));
     }
 
     @Override
-    public SortedSet<V> removeAll(@Nullable Object key) {
+    public SortedSet<V> removeAll(@CheckForNull Object key) {
       throw new UnsupportedOperationException();
     }
 
     @Override
-    public SortedSet<V> replaceValues(K key, Iterable<? extends V> values) {
+    public SortedSet<V> replaceValues(@ParametricNullness K key, Iterable<? extends V> values) {
       throw new UnsupportedOperationException();
     }
 
     @Override
-    public @Nullable Comparator<? super V> valueComparator() {
+    @CheckForNull
+    public Comparator<? super V> valueComparator() {
       return delegate().valueComparator();
     }
 
@@ -862,7 +897,8 @@ public SortedSet<V> replaceValues(K key, Iterable<? extends V> values) {
    * @param multimap the multimap to be wrapped
    * @return a synchronized view of the specified multimap
    */
-  public static <K, V> SetMultimap<K, V> synchronizedSetMultimap(SetMultimap<K, V> multimap) {
+  public static <K extends @Nullable Object, V extends @Nullable Object>
+      SetMultimap<K, V> synchronizedSetMultimap(SetMultimap<K, V> multimap) {
     return Synchronized.setMultimap(multimap, null);
   }
 
@@ -877,7 +913,8 @@ public static <K, V> SetMultimap<K, V> synchronizedSetMultimap(SetMultimap<K, V>
    * @param delegate the multimap for which an unmodifiable view is to be returned
    * @return an unmodifiable view of the specified multimap
    */
-  public static <K, V> SetMultimap<K, V> unmodifiableSetMultimap(SetMultimap<K, V> delegate) {
+  public static <K extends @Nullable Object, V extends @Nullable Object>
+      SetMultimap<K, V> unmodifiableSetMultimap(SetMultimap<K, V> delegate) {
     if (delegate instanceof UnmodifiableSetMultimap || delegate instanceof ImmutableSetMultimap) {
       return delegate;
     }
@@ -907,8 +944,8 @@ public static <K, V> SetMultimap<K, V> unmodifiableSetMultimap(
    * @param multimap the multimap to be wrapped
    * @return a synchronized view of the specified multimap
    */
-  public static <K, V> SortedSetMultimap<K, V> synchronizedSortedSetMultimap(
-      SortedSetMultimap<K, V> multimap) {
+  public static <K extends @Nullable Object, V extends @Nullable Object>
+      SortedSetMultimap<K, V> synchronizedSortedSetMultimap(SortedSetMultimap<K, V> multimap) {
     return Synchronized.sortedSetMultimap(multimap, null);
   }
 
@@ -923,8 +960,8 @@ public static <K, V> SortedSetMultimap<K, V> synchronizedSortedSetMultimap(
    * @param delegate the multimap for which an unmodifiable view is to be returned
    * @return an unmodifiable view of the specified multimap
    */
-  public static <K, V> SortedSetMultimap<K, V> unmodifiableSortedSetMultimap(
-      SortedSetMultimap<K, V> delegate) {
+  public static <K extends @Nullable Object, V extends @Nullable Object>
+      SortedSetMultimap<K, V> unmodifiableSortedSetMultimap(SortedSetMultimap<K, V> delegate) {
     if (delegate instanceof UnmodifiableSortedSetMultimap) {
       return delegate;
     }
@@ -939,7 +976,8 @@ public static <K, V> SortedSetMultimap<K, V> unmodifiableSortedSetMultimap(
    * @param multimap the multimap to be wrapped
    * @return a synchronized view of the specified multimap
    */
-  public static <K, V> ListMultimap<K, V> synchronizedListMultimap(ListMultimap<K, V> multimap) {
+  public static <K extends @Nullable Object, V extends @Nullable Object>
+      ListMultimap<K, V> synchronizedListMultimap(ListMultimap<K, V> multimap) {
     return Synchronized.listMultimap(multimap, null);
   }
 
@@ -954,7 +992,8 @@ public static <K, V> ListMultimap<K, V> synchronizedListMultimap(ListMultimap<K,
    * @param delegate the multimap for which an unmodifiable view is to be returned
    * @return an unmodifiable view of the specified multimap
    */
-  public static <K, V> ListMultimap<K, V> unmodifiableListMultimap(ListMultimap<K, V> delegate) {
+  public static <K extends @Nullable Object, V extends @Nullable Object>
+      ListMultimap<K, V> unmodifiableListMultimap(ListMultimap<K, V> delegate) {
     if (delegate instanceof UnmodifiableListMultimap || delegate instanceof ImmutableListMultimap) {
       return delegate;
     }
@@ -981,7 +1020,8 @@ public static <K, V> ListMultimap<K, V> unmodifiableListMultimap(
    * @param collection the collection for which to return an unmodifiable view
    * @return an unmodifiable view of the collection
    */
-  private static <V> Collection<V> unmodifiableValueCollection(Collection<V> collection) {
+  private static <V extends @Nullable Object> Collection<V> unmodifiableValueCollection(
+      Collection<V> collection) {
     if (collection instanceof SortedSet) {
       return Collections.unmodifiableSortedSet((SortedSet<V>) collection);
     } else if (collection instanceof Set) {
@@ -1000,8 +1040,8 @@ private static <V> Collection<V> unmodifiableValueCollection(Collection<V> colle
    * @param entries the entries for which to return an unmodifiable view
    * @return an unmodifiable view of the entries
    */
-  private static <K, V> Collection<Entry<K, V>> unmodifiableEntries(
-      Collection<Entry<K, V>> entries) {
+  private static <K extends @Nullable Object, V extends @Nullable Object>
+      Collection<Entry<K, V>> unmodifiableEntries(Collection<Entry<K, V>> entries) {
     if (entries instanceof Set) {
       return Maps.unmodifiableEntrySet((Set<Entry<K, V>>) entries);
     }
@@ -1017,7 +1057,8 @@ private static <K, V> Collection<Entry<K, V>> unmodifiableEntries(
   @Beta
   @SuppressWarnings("unchecked")
   // safe by specification of ListMultimap.asMap()
-  public static <K, V> Map<K, List<V>> asMap(ListMultimap<K, V> multimap) {
+  public static <K extends @Nullable Object, V extends @Nullable Object> Map<K, List<V>> asMap(
+      ListMultimap<K, V> multimap) {
     return (Map<K, List<V>>) (Map<K, ?>) multimap.asMap();
   }
 
@@ -1030,7 +1071,8 @@ public static <K, V> Map<K, List<V>> asMap(ListMultimap<K, V> multimap) {
   @Beta
   @SuppressWarnings("unchecked")
   // safe by specification of SetMultimap.asMap()
-  public static <K, V> Map<K, Set<V>> asMap(SetMultimap<K, V> multimap) {
+  public static <K extends @Nullable Object, V extends @Nullable Object> Map<K, Set<V>> asMap(
+      SetMultimap<K, V> multimap) {
     return (Map<K, Set<V>>) (Map<K, ?>) multimap.asMap();
   }
 
@@ -1043,7 +1085,8 @@ public static <K, V> Map<K, Set<V>> asMap(SetMultimap<K, V> multimap) {
   @Beta
   @SuppressWarnings("unchecked")
   // safe by specification of SortedSetMultimap.asMap()
-  public static <K, V> Map<K, SortedSet<V>> asMap(SortedSetMultimap<K, V> multimap) {
+  public static <K extends @Nullable Object, V extends @Nullable Object> Map<K, SortedSet<V>> asMap(
+      SortedSetMultimap<K, V> multimap) {
     return (Map<K, SortedSet<V>>) (Map<K, ?>) multimap.asMap();
   }
 
@@ -1054,7 +1097,8 @@ public static <K, V> Map<K, SortedSet<V>> asMap(SortedSetMultimap<K, V> multimap
    * @since 15.0
    */
   @Beta
-  public static <K, V> Map<K, Collection<V>> asMap(Multimap<K, V> multimap) {
+  public static <K extends @Nullable Object, V extends @Nullable Object>
+      Map<K, Collection<V>> asMap(Multimap<K, V> multimap) {
     return multimap.asMap();
   }
 
@@ -1073,13 +1117,14 @@ public static <K, V> Map<K, Collection<V>> asMap(Multimap<K, V> multimap) {
    *
    * @param map the backing map for the returned multimap view
    */
-  public static <K, V> SetMultimap<K, V> forMap(Map<K, V> map) {
+  public static <K extends @Nullable Object, V extends @Nullable Object> SetMultimap<K, V> forMap(
+      Map<K, V> map) {
     return new MapMultimap<>(map);
   }
 
   /** @see Multimaps#forMap */
-  private static class MapMultimap<K, V> extends AbstractMultimap<K, V>
-      implements SetMultimap<K, V>, Serializable {
+  private static class MapMultimap<K extends @Nullable Object, V extends @Nullable Object>
+      extends AbstractMultimap<K, V> implements SetMultimap<K, V>, Serializable {
     final Map<K, V> map;
 
     MapMultimap(Map<K, V> map) {
@@ -1094,24 +1139,24 @@ public int size() {
 
     @Pure
     @Override
-    public boolean containsKey(@Nullable Object key) {
+    public boolean containsKey(@CheckForNull Object key) {
       return map.containsKey(key);
     }
 
     @Pure
     @Override
-    public boolean containsValue(@Nullable Object value) {
+    public boolean containsValue(@CheckForNull Object value) {
       return map.containsValue(value);
     }
 
     @Pure
     @Override
-    public boolean containsEntry(@Nullable Object key, @Nullable Object value) {
+    public boolean containsEntry(@CheckForNull Object key, @CheckForNull Object value) {
       return map.entrySet().contains(Maps.immutableEntry(key, value));
     }
 
     @Override
-    public Set<V> get(final K key) {
+    public Set<V> get(@ParametricNullness final K key) {
       return new Sets.ImprovedAbstractSet<V>() {
         @Override
         public Iterator<V> iterator() {
@@ -1124,12 +1169,17 @@ public boolean hasNext() {
             }
 
             @Override
+            @ParametricNullness
             public V next() {
               if (!hasNext()) {
                 throw new NoSuchElementException();
               }
               i++;
-              return map.get(key);
+              /*
+               * The cast is safe because of the containsKey check in hasNext(). (That means it's
+               * unsafe under concurrent modification, but all bets are off then, anyway.)
+               */
+              return uncheckedCastNullableTToT(map.get(key));
             }
 
             @Override
@@ -1150,12 +1200,12 @@ public int size() {
     }
 
     @Override
-    public boolean put(K key, V value) {
+    public boolean put(@ParametricNullness K key, @ParametricNullness V value) {
       throw new UnsupportedOperationException();
     }
 
     @Override
-    public boolean putAll(K key, Iterable<? extends V> values) {
+    public boolean putAll(@ParametricNullness K key, Iterable<? extends V> values) {
       throw new UnsupportedOperationException();
     }
 
@@ -1165,17 +1215,17 @@ public boolean putAll(Multimap<? extends K, ? extends V> multimap) {
     }
 
     @Override
-    public Set<V> replaceValues(K key, Iterable<? extends V> values) {
+    public Set<V> replaceValues(@ParametricNullness K key, Iterable<? extends V> values) {
       throw new UnsupportedOperationException();
     }
 
     @Override
-    public boolean remove(@Nullable Object key, @Nullable Object value) {
+    public boolean remove(@CheckForNull Object key, @CheckForNull Object value) {
       return map.entrySet().remove(Maps.immutableEntry(key, value));
     }
 
     @Override
-    public Set<V> removeAll(@Nullable Object key) {
+    public Set<V> removeAll(@CheckForNull Object key) {
       Set<V> values = new HashSet<V>(2);
       if (!map.containsKey(key)) {
         return values;
@@ -1277,8 +1327,10 @@ public int hashCode() {
    *
    * @since 7.0
    */
-  public static <K, V1, V2> Multimap<K, V2> transformValues(
-      Multimap<K, V1> fromMultimap, final Function<? super V1, V2> function) {
+  public static <
+          K extends @Nullable Object, V1 extends @Nullable Object, V2 extends @Nullable Object>
+      Multimap<K, V2> transformValues(
+          Multimap<K, V1> fromMultimap, final Function<? super V1, V2> function) {
     checkNotNull(function);
     EntryTransformer<K, V1, V2> transformer = Maps.asEntryTransformer(function);
     return transformEntries(fromMultimap, transformer);
@@ -1324,8 +1376,10 @@ public static <K, V1, V2> Multimap<K, V2> transformValues(
    *
    * @since 7.0
    */
-  public static <K, V1, V2> ListMultimap<K, V2> transformValues(
-      ListMultimap<K, V1> fromMultimap, final Function<? super V1, V2> function) {
+  public static <
+          K extends @Nullable Object, V1 extends @Nullable Object, V2 extends @Nullable Object>
+      ListMultimap<K, V2> transformValues(
+          ListMultimap<K, V1> fromMultimap, final Function<? super V1, V2> function) {
     checkNotNull(function);
     EntryTransformer<K, V1, V2> transformer = Maps.asEntryTransformer(function);
     return transformEntries(fromMultimap, transformer);
@@ -1382,8 +1436,10 @@ public static <K, V1, V2> ListMultimap<K, V2> transformValues(
    *
    * @since 7.0
    */
-  public static <K, V1, V2> Multimap<K, V2> transformEntries(
-      Multimap<K, V1> fromMap, EntryTransformer<? super K, ? super V1, V2> transformer) {
+  public static <
+          K extends @Nullable Object, V1 extends @Nullable Object, V2 extends @Nullable Object>
+      Multimap<K, V2> transformEntries(
+          Multimap<K, V1> fromMap, EntryTransformer<? super K, ? super V1, V2> transformer) {
     return new TransformedEntriesMultimap<>(fromMap, transformer);
   }
 
@@ -1435,12 +1491,16 @@ public static <K, V1, V2> Multimap<K, V2> transformEntries(
    *
    * @since 7.0
    */
-  public static <K, V1, V2> ListMultimap<K, V2> transformEntries(
-      ListMultimap<K, V1> fromMap, EntryTransformer<? super K, ? super V1, V2> transformer) {
+  public static <
+          K extends @Nullable Object, V1 extends @Nullable Object, V2 extends @Nullable Object>
+      ListMultimap<K, V2> transformEntries(
+          ListMultimap<K, V1> fromMap, EntryTransformer<? super K, ? super V1, V2> transformer) {
     return new TransformedEntriesListMultimap<>(fromMap, transformer);
   }
 
-  private static class TransformedEntriesMultimap<K, V1, V2> extends AbstractMultimap<K, V2> {
+  private static class TransformedEntriesMultimap<
+          K extends @Nullable Object, V1 extends @Nullable Object, V2 extends @Nullable Object>
+      extends AbstractMultimap<K, V2> {
     final Multimap<K, V1> fromMultimap;
     final EntryTransformer<? super K, ? super V1, V2> transformer;
 
@@ -1451,7 +1511,7 @@ private static class TransformedEntriesMultimap<K, V1, V2> extends AbstractMulti
       this.transformer = checkNotNull(transformer);
     }
 
-    Collection<V2> transform(K key, Collection<V1> values) {
+    Collection<V2> transform(@ParametricNullness K key, Collection<V1> values) {
       Function<? super V1, V2> function = Maps.asValueToValueFunction(transformer, key);
       if (values instanceof List) {
         return Lists.transform((List<V1>) values, function);
@@ -1466,7 +1526,7 @@ Map<K, Collection<V2>> createAsMap() {
           fromMultimap.asMap(),
           new EntryTransformer<K, Collection<V1>, Collection<V2>>() {
             @Override
-            public Collection<V2> transformEntry(K key, Collection<V1> value) {
+            public Collection<V2> transformEntry(@ParametricNullness K key, Collection<V1> value) {
               return transform(key, value);
             }
           });
@@ -1478,7 +1538,7 @@ public void clear() {
     }
 
     @Override
-    public boolean containsKey(Object key) {
+    public boolean containsKey(@CheckForNull Object key) {
       return fromMultimap.containsKey(key);
     }
 
@@ -1494,7 +1554,7 @@ Iterator<Entry<K, V2>> entryIterator() {
     }
 
     @Override
-    public Collection<V2> get(final K key) {
+    public Collection<V2> get(@ParametricNullness final K key) {
       return transform(key, fromMultimap.get(key));
     }
 
@@ -1514,12 +1574,12 @@ Multiset<K> createKeys() {
     }
 
     @Override
-    public boolean put(K key, V2 value) {
+    public boolean put(@ParametricNullness K key, @ParametricNullness V2 value) {
       throw new UnsupportedOperationException();
     }
 
     @Override
-    public boolean putAll(K key, Iterable<? extends V2> values) {
+    public boolean putAll(@ParametricNullness K key, Iterable<? extends V2> values) {
       throw new UnsupportedOperationException();
     }
 
@@ -1530,18 +1590,18 @@ public boolean putAll(Multimap<? extends K, ? extends V2> multimap) {
 
     @SuppressWarnings("unchecked")
     @Override
-    public boolean remove(Object key, Object value) {
+    public boolean remove(@CheckForNull Object key, @CheckForNull Object value) {
       return get((K) key).remove(value);
     }
 
     @SuppressWarnings("unchecked")
     @Override
-    public Collection<V2> removeAll(Object key) {
+    public Collection<V2> removeAll(@CheckForNull Object key) {
       return transform((K) key, fromMultimap.removeAll(key));
     }
 
     @Override
-    public Collection<V2> replaceValues(K key, Iterable<? extends V2> values) {
+    public Collection<V2> replaceValues(@ParametricNullness K key, Iterable<? extends V2> values) {
       throw new UnsupportedOperationException();
     }
 
@@ -1557,7 +1617,8 @@ Collection<V2> createValues() {
     }
   }
 
-  private static final class TransformedEntriesListMultimap<K, V1, V2>
+  private static final class TransformedEntriesListMultimap<
+          K extends @Nullable Object, V1 extends @Nullable Object, V2 extends @Nullable Object>
       extends TransformedEntriesMultimap<K, V1, V2> implements ListMultimap<K, V2> {
 
     TransformedEntriesListMultimap(
@@ -1566,23 +1627,23 @@ private static final class TransformedEntriesListMultimap<K, V1, V2>
     }
 
     @Override
-    List<V2> transform(K key, Collection<V1> values) {
+    List<V2> transform(@ParametricNullness K key, Collection<V1> values) {
       return Lists.transform((List<V1>) values, Maps.asValueToValueFunction(transformer, key));
     }
 
     @Override
-    public List<V2> get(K key) {
+    public List<V2> get(@ParametricNullness K key) {
       return transform(key, fromMultimap.get(key));
     }
 
     @SuppressWarnings("unchecked")
     @Override
-    public List<V2> removeAll(Object key) {
+    public List<V2> removeAll(@CheckForNull Object key) {
       return transform((K) key, fromMultimap.removeAll(key));
     }
 
     @Override
-    public List<V2> replaceValues(K key, Iterable<? extends V2> values) {
+    public List<V2> replaceValues(@ParametricNullness K key, Iterable<? extends V2> values) {
       throw new UnsupportedOperationException();
     }
   }
@@ -1675,7 +1736,8 @@ public static <K, V> ImmutableListMultimap<K, V> index(
     return builder.build();
   }
 
-  static class Keys<K, V> extends AbstractMultiset<K> {
+  static class Keys<K extends @Nullable Object, V extends @Nullable Object>
+      extends AbstractMultiset<K> {
     @Weak final Multimap<K, V> multimap;
 
     Keys(Multimap<K, V> multimap) {
@@ -1690,6 +1752,7 @@ Iterator<Multiset.Entry<K>> entryIterator() {
         Multiset.Entry<K> transform(final Map.Entry<K, Collection<V>> backingEntry) {
           return new Multisets.AbstractEntry<K>() {
             @Override
+            @ParametricNullness
             public K getElement() {
               return backingEntry.getKey();
             }
@@ -1725,7 +1788,7 @@ public int size() {
     }
 
     @Override
-    public boolean contains(@Nullable Object element) {
+    public boolean contains(@CheckForNull Object element) {
       return multimap.containsKey(element);
     }
 
@@ -1735,13 +1798,13 @@ public Iterator<K> iterator() {
     }
 
     @Override
-    public int count(@Nullable Object element) {
+    public int count(@CheckForNull Object element) {
       Collection<V> values = Maps.safeGet(multimap.asMap(), element);
       return (values == null) ? 0 : values.size();
     }
 
     @Override
-    public int remove(@Nullable Object element, int occurrences) {
+    public int remove(@CheckForNull Object element, int occurrences) {
       checkNonnegative(occurrences, "occurrences");
       if (occurrences == 0) {
         return count(element);
@@ -1783,7 +1846,8 @@ Iterator<K> elementIterator() {
   }
 
   /** A skeleton implementation of {@link Multimap#entries()}. */
-  abstract static class Entries<K, V> extends AbstractCollection<Map.Entry<K, V>> {
+  abstract static class Entries<K extends @Nullable Object, V extends @Nullable Object>
+      extends AbstractCollection<Map.Entry<K, V>> {
     abstract Multimap<K, V> multimap();
 
     @Override
@@ -1792,7 +1856,7 @@ public int size() {
     }
 
     @Override
-    public boolean contains(@Nullable Object o) {
+    public boolean contains(@CheckForNull Object o) {
       if (o instanceof Map.Entry) {
         Map.Entry<?, ?> entry = (Map.Entry<?, ?>) o;
         return multimap().containsEntry(entry.getKey(), entry.getValue());
@@ -1801,7 +1865,7 @@ public boolean contains(@Nullable Object o) {
     }
 
     @Override
-    public boolean remove(@Nullable Object o) {
+    public boolean remove(@CheckForNull Object o) {
       if (o instanceof Map.Entry) {
         Map.Entry<?, ?> entry = (Map.Entry<?, ?>) o;
         return multimap().remove(entry.getKey(), entry.getValue());
@@ -1816,7 +1880,8 @@ public void clear() {
   }
 
   /** A skeleton implementation of {@link Multimap#asMap()}. */
-  static final class AsMap<K, V> extends Maps.ViewCachingAbstractMap<K, Collection<V>> {
+  static final class AsMap<K extends @Nullable Object, V extends @Nullable Object>
+      extends Maps.ViewCachingAbstractMap<K, Collection<V>> {
     @Weak private final Multimap<K, V> multimap;
 
     AsMap(Multimap<K, V> multimap) {
@@ -1833,7 +1898,7 @@ protected Set<Entry<K, Collection<V>>> createEntrySet() {
       return new EntrySet();
     }
 
-    void removeValuesForKey(Object key) {
+    void removeValuesForKey(@CheckForNull Object key) {
       multimap.keySet().remove(key);
     }
 
@@ -1850,18 +1915,19 @@ public Iterator<Entry<K, Collection<V>>> iterator() {
             multimap.keySet(),
             new Function<K, Collection<V>>() {
               @Override
-              public Collection<V> apply(K key) {
+              public Collection<V> apply(@ParametricNullness K key) {
                 return multimap.get(key);
               }
             });
       }
 
       @Override
-      public boolean remove(Object o) {
+      public boolean remove(@CheckForNull Object o) {
         if (!contains(o)) {
           return false;
         }
-        Map.Entry<?, ?> entry = (Map.Entry<?, ?>) o;
+        // requireNonNull is safe because of the contains check.
+        Map.Entry<?, ?> entry = requireNonNull((Map.Entry<?, ?>) o);
         removeValuesForKey(entry.getKey());
         return true;
       }
@@ -1869,12 +1935,14 @@ public boolean remove(Object o) {
 
     @SuppressWarnings("unchecked")
     @Override
-    public Collection<V> get(Object key) {
+    @CheckForNull
+    public Collection<V> get(@CheckForNull Object key) {
       return containsKey(key) ? multimap.get((K) key) : null;
     }
 
     @Override
-    public Collection<V> remove(Object key) {
+    @CheckForNull
+    public Collection<V> remove(@CheckForNull Object key) {
       return containsKey(key) ? multimap.removeAll(key) : null;
     }
 
@@ -1889,7 +1957,7 @@ public boolean isEmpty() {
     }
 
     @Override
-    public boolean containsKey(Object key) {
+    public boolean containsKey(@CheckForNull Object key) {
       return multimap.containsKey(key);
     }
 
@@ -1926,7 +1994,7 @@ public void clear() {
    *
    * @since 11.0
    */
-  public static <K, V> Multimap<K, V> filterKeys(
+  public static <K extends @Nullable Object, V extends @Nullable Object> Multimap<K, V> filterKeys(
       Multimap<K, V> unfiltered, final Predicate<? super K> keyPredicate) {
     if (unfiltered instanceof SetMultimap) {
       return filterKeys((SetMultimap<K, V>) unfiltered, keyPredicate);
@@ -1971,8 +2039,9 @@ public static <K, V> Multimap<K, V> filterKeys(
    *
    * @since 14.0
    */
-  public static <K, V> SetMultimap<K, V> filterKeys(
-      SetMultimap<K, V> unfiltered, final Predicate<? super K> keyPredicate) {
+  public static <K extends @Nullable Object, V extends @Nullable Object>
+      SetMultimap<K, V> filterKeys(
+          SetMultimap<K, V> unfiltered, final Predicate<? super K> keyPredicate) {
     if (unfiltered instanceof FilteredKeySetMultimap) {
       FilteredKeySetMultimap<K, V> prev = (FilteredKeySetMultimap<K, V>) unfiltered;
       return new FilteredKeySetMultimap<>(
@@ -2012,8 +2081,9 @@ public static <K, V> SetMultimap<K, V> filterKeys(
    *
    * @since 14.0
    */
-  public static <K, V> ListMultimap<K, V> filterKeys(
-      ListMultimap<K, V> unfiltered, final Predicate<? super K> keyPredicate) {
+  public static <K extends @Nullable Object, V extends @Nullable Object>
+      ListMultimap<K, V> filterKeys(
+          ListMultimap<K, V> unfiltered, final Predicate<? super K> keyPredicate) {
     if (unfiltered instanceof FilteredKeyListMultimap) {
       FilteredKeyListMultimap<K, V> prev = (FilteredKeyListMultimap<K, V>) unfiltered;
       return new FilteredKeyListMultimap<>(
@@ -2050,8 +2120,9 @@ public static <K, V> ListMultimap<K, V> filterKeys(
    *
    * @since 11.0
    */
-  public static <K, V> Multimap<K, V> filterValues(
-      Multimap<K, V> unfiltered, final Predicate<? super V> valuePredicate) {
+  public static <K extends @Nullable Object, V extends @Nullable Object>
+      Multimap<K, V> filterValues(
+          Multimap<K, V> unfiltered, final Predicate<? super V> valuePredicate) {
     return filterEntries(unfiltered, Maps.<V>valuePredicateOnEntries(valuePredicate));
   }
 
@@ -2082,8 +2153,9 @@ public static <K, V> Multimap<K, V> filterValues(
    *
    * @since 14.0
    */
-  public static <K, V> SetMultimap<K, V> filterValues(
-      SetMultimap<K, V> unfiltered, final Predicate<? super V> valuePredicate) {
+  public static <K extends @Nullable Object, V extends @Nullable Object>
+      SetMultimap<K, V> filterValues(
+          SetMultimap<K, V> unfiltered, final Predicate<? super V> valuePredicate) {
     return filterEntries(unfiltered, Maps.<V>valuePredicateOnEntries(valuePredicate));
   }
 
@@ -2112,8 +2184,9 @@ public static <K, V> SetMultimap<K, V> filterValues(
    *
    * @since 11.0
    */
-  public static <K, V> Multimap<K, V> filterEntries(
-      Multimap<K, V> unfiltered, Predicate<? super Entry<K, V>> entryPredicate) {
+  public static <K extends @Nullable Object, V extends @Nullable Object>
+      Multimap<K, V> filterEntries(
+          Multimap<K, V> unfiltered, Predicate<? super Entry<K, V>> entryPredicate) {
     checkNotNull(entryPredicate);
     if (unfiltered instanceof SetMultimap) {
       return filterEntries((SetMultimap<K, V>) unfiltered, entryPredicate);
@@ -2148,8 +2221,9 @@ public static <K, V> Multimap<K, V> filterEntries(
    *
    * @since 14.0
    */
-  public static <K, V> SetMultimap<K, V> filterEntries(
-      SetMultimap<K, V> unfiltered, Predicate<? super Entry<K, V>> entryPredicate) {
+  public static <K extends @Nullable Object, V extends @Nullable Object>
+      SetMultimap<K, V> filterEntries(
+          SetMultimap<K, V> unfiltered, Predicate<? super Entry<K, V>> entryPredicate) {
     checkNotNull(entryPredicate);
     return (unfiltered instanceof FilteredSetMultimap)
         ? filterFiltered((FilteredSetMultimap<K, V>) unfiltered, entryPredicate)
@@ -2162,8 +2236,9 @@ public static <K, V> SetMultimap<K, V> filterEntries(
    * lead to a multimap whose removal operations would fail. This method combines the predicates to
    * avoid that problem.
    */
-  private static <K, V> Multimap<K, V> filterFiltered(
-      FilteredMultimap<K, V> multimap, Predicate<? super Entry<K, V>> entryPredicate) {
+  private static <K extends @Nullable Object, V extends @Nullable Object>
+      Multimap<K, V> filterFiltered(
+          FilteredMultimap<K, V> multimap, Predicate<? super Entry<K, V>> entryPredicate) {
     Predicate<Entry<K, V>> predicate =
         Predicates.<Entry<K, V>>and(multimap.entryPredicate(), entryPredicate);
     return new FilteredEntryMultimap<>(multimap.unfiltered(), predicate);
@@ -2175,14 +2250,15 @@ private static <K, V> Multimap<K, V> filterFiltered(
    * lead to a multimap whose removal operations would fail. This method combines the predicates to
    * avoid that problem.
    */
-  private static <K, V> SetMultimap<K, V> filterFiltered(
-      FilteredSetMultimap<K, V> multimap, Predicate<? super Entry<K, V>> entryPredicate) {
+  private static <K extends @Nullable Object, V extends @Nullable Object>
+      SetMultimap<K, V> filterFiltered(
+          FilteredSetMultimap<K, V> multimap, Predicate<? super Entry<K, V>> entryPredicate) {
     Predicate<Entry<K, V>> predicate =
         Predicates.<Entry<K, V>>and(multimap.entryPredicate(), entryPredicate);
     return new FilteredEntrySetMultimap<>(multimap.unfiltered(), predicate);
   }
 
-  static boolean equalsImpl(Multimap<?, ?> multimap, @Nullable Object object) {
+  static boolean equalsImpl(Multimap<?, ?> multimap, @CheckForNull Object object) {
     if (object == multimap) {
       return true;
     }
diff --git a/guava/src/com/google/common/collect/Multiset.java b/guava/src/com/google/common/collect/Multiset.java
index b7fa165778ba..501428797803 100644
--- a/guava/src/com/google/common/collect/Multiset.java
+++ b/guava/src/com/google/common/collect/Multiset.java
@@ -30,6 +30,7 @@
 import java.util.Spliterator;
 import java.util.function.Consumer;
 import java.util.function.ObjIntConsumer;
+import javax.annotation.CheckForNull;
 import org.checkerframework.checker.nullness.qual.Nullable;
 import org.checkerframework.checker.signedness.qual.UnknownSignedness;
 import org.checkerframework.dataflow.qual.Pure;
@@ -71,6 +72,10 @@
  * <p>A multiset uses {@link Object#equals} to determine whether two instances should be considered
  * "the same," <i>unless specified otherwise</i> by the implementation.
  *
+ * <p><b>Warning:</b> as with normal {@link Set}s, it is almost always a bad idea to modify an
+ * element (in a way that affects its {@link Object#equals} behavior) while it is contained in a
+ * multiset. Undefined behavior and bugs will result.
+ *
  * <p>Common implementations include {@link ImmutableMultiset}, {@link HashMultiset}, and {@link
  * ConcurrentHashMultiset}.
  *
@@ -79,15 +84,15 @@
  * {@code Multiset}, {@code AtomicLongMap} does not automatically remove zeros.
  *
  * <p>See the Guava User Guide article on <a href=
- * "https://github.com/google/guava/wiki/NewCollectionTypesExplained#multiset"> {@code
- * Multiset}</a>.
+ * "https://github.com/google/guava/wiki/NewCollectionTypesExplained#multiset">{@code Multiset}</a>.
  *
  * @author Kevin Bourrillion
  * @since 2.0
  */
 @AnnotatedFor({"nullness"})
 @GwtCompatible
-public interface Multiset<E> extends Collection<E> {
+@ElementTypesAreNonnullByDefault
+public interface Multiset<E extends @Nullable Object> extends Collection<E> {
   // Query Operations
 
   /**
@@ -112,7 +117,7 @@ public interface Multiset<E> extends Collection<E> {
    * @return the number of occurrences of the element in this multiset; possibly zero but never
    *     negative
    */
-  int count(@CompatibleWith("E") @Nullable Object element);
+  int count(@CompatibleWith("E") @CheckForNull Object element);
 
   // Bulk Operations
 
@@ -135,7 +140,7 @@ public interface Multiset<E> extends Collection<E> {
    *     return normally.
    */
   @CanIgnoreReturnValue
-  int add(@Nullable E element, int occurrences);
+  int add(@ParametricNullness E element, int occurrences);
 
   /**
    * Adds a single occurrence of the specified element to this multiset.
@@ -158,7 +163,7 @@ public interface Multiset<E> extends Collection<E> {
    */
   @CanIgnoreReturnValue
   @Override
-  boolean add(E element);
+  boolean add(@ParametricNullness E element);
 
   /**
    * Removes a number of occurrences of the specified element from this multiset. If the multiset
@@ -173,7 +178,7 @@ public interface Multiset<E> extends Collection<E> {
    * @throws IllegalArgumentException if {@code occurrences} is negative
    */
   @CanIgnoreReturnValue
-  int remove(@CompatibleWith("E") @Nullable Object element, int occurrences);
+  int remove(@CompatibleWith("E") @CheckForNull Object element, int occurrences);
 
   /**
    * Removes a <i>single</i> occurrence of the specified element from this multiset, if present.
@@ -189,7 +194,7 @@ public interface Multiset<E> extends Collection<E> {
    */
   @CanIgnoreReturnValue
   @Override
-  boolean remove(@Nullable @UnknownSignedness Object element);
+  boolean remove(@CheckForNull @UnknownSignedness Object element);
 
   /**
    * Adds or removes the necessary occurrences of an element such that the element attains the
@@ -205,7 +210,7 @@ public interface Multiset<E> extends Collection<E> {
    *     zero instead.
    */
   @CanIgnoreReturnValue
-  int setCount(E element, int count);
+  int setCount(@ParametricNullness E element, int count);
 
   /**
    * Conditionally sets the count of an element to a new value, as described in {@link
@@ -224,7 +229,7 @@ public interface Multiset<E> extends Collection<E> {
    *     implementor may optionally return {@code true} instead.
    */
   @CanIgnoreReturnValue
-  boolean setCount(E element, int oldCount, int newCount);
+  boolean setCount(@ParametricNullness E element, int oldCount, int newCount);
 
   // Views
 
@@ -270,7 +275,7 @@ public interface Multiset<E> extends Collection<E> {
    *
    * @since 2.0
    */
-  interface Entry<E> {
+  interface Entry<E extends @Nullable Object> {
 
     /**
      * Returns the multiset element corresponding to this entry. Multiple calls to this method
@@ -278,6 +283,7 @@ interface Entry<E> {
      *
      * @return the element corresponding to this entry
      */
+    @ParametricNullness
     E getElement();
 
     /**
@@ -306,7 +312,7 @@ interface Entry<E> {
     @Pure
     @Override
     // TODO(kevinb): check this wrt TreeMultiset?
-    boolean equals(@Nullable Object o);
+    boolean equals(@CheckForNull Object o);
 
     /**
      * {@inheritDoc}
@@ -357,7 +363,7 @@ default void forEachEntry(ObjIntConsumer<? super E> action) {
   @Pure
   @Override
   // TODO(kevinb): caveats about equivalence-relation?
-  boolean equals(@Nullable @UnknownSignedness Object object);
+  boolean equals(@CheckForNull @UnknownSignedness Object object);
 
   /**
    * Returns the hash code for this multiset. This is defined as the sum of
@@ -406,7 +412,7 @@ default void forEachEntry(ObjIntConsumer<? super E> action) {
    */
   @Pure
   @Override
-  boolean contains(@Nullable @UnknownSignedness Object element);
+  boolean contains(@CheckForNull @UnknownSignedness Object element);
 
   /**
    * Returns {@code true} if this multiset contains at least one occurrence of each element in the
diff --git a/guava/src/com/google/common/collect/Multisets.java b/guava/src/com/google/common/collect/Multisets.java
index 080718f3a3a9..afb5bf67ba47 100644
--- a/guava/src/com/google/common/collect/Multisets.java
+++ b/guava/src/com/google/common/collect/Multisets.java
@@ -20,6 +20,7 @@
 import static com.google.common.base.Preconditions.checkNotNull;
 import static com.google.common.collect.CollectPreconditions.checkNonnegative;
 import static com.google.common.collect.CollectPreconditions.checkRemove;
+import static java.util.Objects.requireNonNull;
 
 import com.google.common.annotations.Beta;
 import com.google.common.annotations.GwtCompatible;
@@ -39,7 +40,11 @@
 import java.util.NoSuchElementException;
 import java.util.Set;
 import java.util.Spliterator;
+import java.util.function.Function;
+import java.util.function.Supplier;
+import java.util.function.ToIntFunction;
 import java.util.stream.Collector;
+import javax.annotation.CheckForNull;
 import org.checkerframework.checker.nullness.qual.Nullable;
 import org.checkerframework.dataflow.qual.Pure;
 import org.checkerframework.dataflow.qual.SideEffectFree;
@@ -49,7 +54,7 @@
  * Provides static utility methods for creating and working with {@link Multiset} instances.
  *
  * <p>See the Guava User Guide article on <a href=
- * "https://github.com/google/guava/wiki/CollectionUtilitiesExplained#multisets"> {@code
+ * "https://github.com/google/guava/wiki/CollectionUtilitiesExplained#multisets">{@code
  * Multisets}</a>.
  *
  * @author Kevin Bourrillion
@@ -59,6 +64,7 @@
  */
 @AnnotatedFor({"nullness"})
 @GwtCompatible
+@ElementTypesAreNonnullByDefault
 public final class Multisets {
   private Multisets() {}
 
@@ -74,12 +80,16 @@ private Multisets() {}
    * <p>Note that {@code stream.collect(toMultiset(function, e -> 1, supplier))} is equivalent to
    * {@code stream.map(function).collect(Collectors.toCollection(supplier))}.
    *
+   * <p>To collect to an {@link ImmutableMultiset}, use {@link
+   * ImmutableMultiset#toImmutableMultiset}.
+   *
    * @since 22.0
    */
-  public static <T, E, M extends Multiset<E>> Collector<T, ?, M> toMultiset(
-      java.util.function.Function<? super T, E> elementFunction,
-      java.util.function.ToIntFunction<? super T> countFunction,
-      java.util.function.Supplier<M> multisetSupplier) {
+  public static <T extends @Nullable Object, E extends @Nullable Object, M extends Multiset<E>>
+      Collector<T, ?, M> toMultiset(
+          Function<? super T, E> elementFunction,
+          ToIntFunction<? super T> countFunction,
+          Supplier<M> multisetSupplier) {
     return CollectCollectors.toMultiset(elementFunction, countFunction, multisetSupplier);
   }
 
@@ -93,7 +103,8 @@ private Multisets() {}
    * @param multiset the multiset for which an unmodifiable view is to be generated
    * @return an unmodifiable view of the multiset
    */
-  public static <E> Multiset<E> unmodifiableMultiset(Multiset<? extends E> multiset) {
+  public static <E extends @Nullable Object> Multiset<E> unmodifiableMultiset(
+      Multiset<? extends E> multiset) {
     if (multiset instanceof UnmodifiableMultiset || multiset instanceof ImmutableMultiset) {
       @SuppressWarnings("unchecked") // Since it's unmodifiable, the covariant cast is safe
       Multiset<E> result = (Multiset<E>) multiset;
@@ -113,7 +124,8 @@ public static <E> Multiset<E> unmodifiableMultiset(ImmutableMultiset<E> multiset
     return checkNotNull(multiset);
   }
 
-  static class UnmodifiableMultiset<E> extends ForwardingMultiset<E> implements Serializable {
+  static class UnmodifiableMultiset<E extends @Nullable Object> extends ForwardingMultiset<E>
+      implements Serializable {
     final Multiset<? extends E> delegate;
 
     UnmodifiableMultiset(Multiset<? extends E> delegate) {
@@ -127,7 +139,7 @@ protected Multiset<E> delegate() {
       return (Multiset<E>) delegate;
     }
 
-    transient @Nullable Set<E> elementSet;
+    @CheckForNull transient Set<E> elementSet;
 
     Set<E> createElementSet() {
       return Collections.<E>unmodifiableSet(delegate.elementSet());
@@ -140,7 +152,7 @@ public Set<E> elementSet() {
       return (es == null) ? elementSet = createElementSet() : es;
     }
 
-    transient @Nullable Set<Multiset.Entry<E>> entrySet;
+    @CheckForNull transient Set<Multiset.Entry<E>> entrySet;
 
     @SideEffectFree
     @SuppressWarnings("unchecked")
@@ -160,12 +172,12 @@ public Iterator<E> iterator() {
     }
 
     @Override
-    public boolean add(E element) {
+    public boolean add(@ParametricNullness E element) {
       throw new UnsupportedOperationException();
     }
 
     @Override
-    public int add(E element, int occurences) {
+    public int add(@ParametricNullness E element, int occurrences) {
       throw new UnsupportedOperationException();
     }
 
@@ -175,12 +187,12 @@ public boolean addAll(Collection<? extends E> elementsToAdd) {
     }
 
     @Override
-    public boolean remove(@Nullable Object element) {
+    public boolean remove(@CheckForNull Object element) {
       throw new UnsupportedOperationException();
     }
 
     @Override
-    public int remove(@Nullable Object element, int occurrences) {
+    public int remove(@CheckForNull Object element, int occurrences) {
       throw new UnsupportedOperationException();
     }
 
@@ -200,12 +212,12 @@ public void clear() {
     }
 
     @Override
-    public int setCount(E element, int count) {
+    public int setCount(@ParametricNullness E element, int count) {
       throw new UnsupportedOperationException();
     }
 
     @Override
-    public boolean setCount(E element, int oldCount, int newCount) {
+    public boolean setCount(@ParametricNullness E element, int oldCount, int newCount) {
       throw new UnsupportedOperationException();
     }
 
@@ -224,7 +236,8 @@ public boolean setCount(E element, int oldCount, int newCount) {
    * @since 11.0
    */
   @Beta
-  public static <E> SortedMultiset<E> unmodifiableSortedMultiset(SortedMultiset<E> sortedMultiset) {
+  public static <E extends @Nullable Object> SortedMultiset<E> unmodifiableSortedMultiset(
+      SortedMultiset<E> sortedMultiset) {
     // it's in its own file so it can be emulated for GWT
     return new UnmodifiableSortedMultiset<E>(checkNotNull(sortedMultiset));
   }
@@ -237,22 +250,25 @@ public static <E> SortedMultiset<E> unmodifiableSortedMultiset(SortedMultiset<E>
    * @param n the count to be associated with the returned entry
    * @throws IllegalArgumentException if {@code n} is negative
    */
-  public static <E> Multiset.Entry<E> immutableEntry(@Nullable E e, int n) {
+  public static <E extends @Nullable Object> Multiset.Entry<E> immutableEntry(
+      @ParametricNullness E e, int n) {
     return new ImmutableEntry<E>(e, n);
   }
 
-  static class ImmutableEntry<E> extends AbstractEntry<E> implements Serializable {
-    private final @Nullable E element;
+  static class ImmutableEntry<E extends @Nullable Object> extends AbstractEntry<E>
+      implements Serializable {
+    @ParametricNullness private final E element;
     private final int count;
 
-    ImmutableEntry(@Nullable E element, int count) {
+    ImmutableEntry(@ParametricNullness E element, int count) {
       this.element = element;
       this.count = count;
       checkNonnegative(count, "count");
     }
 
     @Override
-    public final @Nullable E getElement() {
+    @ParametricNullness
+    public final E getElement() {
       return element;
     }
 
@@ -261,6 +277,7 @@ public final int getCount() {
       return count;
     }
 
+    @CheckForNull
     public ImmutableEntry<E> nextInBucket() {
       return null;
     }
@@ -294,7 +311,8 @@ public ImmutableEntry<E> nextInBucket() {
    * @since 14.0
    */
   @Beta
-  public static <E> Multiset<E> filter(Multiset<E> unfiltered, Predicate<? super E> predicate) {
+  public static <E extends @Nullable Object> Multiset<E> filter(
+      Multiset<E> unfiltered, Predicate<? super E> predicate) {
     if (unfiltered instanceof FilteredMultiset) {
       // Support clear(), removeAll(), and retainAll() when filtering a filtered
       // collection.
@@ -305,7 +323,7 @@ public static <E> Multiset<E> filter(Multiset<E> unfiltered, Predicate<? super E
     return new FilteredMultiset<E>(unfiltered, predicate);
   }
 
-  private static final class FilteredMultiset<E> extends ViewMultiset<E> {
+  private static final class FilteredMultiset<E extends @Nullable Object> extends ViewMultiset<E> {
     final Multiset<E> unfiltered;
     final Predicate<? super E> predicate;
 
@@ -347,7 +365,7 @@ Iterator<Entry<E>> entryIterator() {
     }
 
     @Override
-    public int count(@Nullable Object element) {
+    public int count(@CheckForNull Object element) {
       int count = unfiltered.count(element);
       if (count > 0) {
         @SuppressWarnings("unchecked") // element is equal to an E
@@ -358,14 +376,14 @@ public int count(@Nullable Object element) {
     }
 
     @Override
-    public int add(@Nullable E element, int occurrences) {
+    public int add(@ParametricNullness E element, int occurrences) {
       checkArgument(
           predicate.apply(element), "Element %s does not match predicate %s", element, predicate);
       return unfiltered.add(element, occurrences);
     }
 
     @Override
-    public int remove(@Nullable Object element, int occurrences) {
+    public int remove(@CheckForNull Object element, int occurrences) {
       checkNonnegative(occurrences, "occurrences");
       if (occurrences == 0) {
         return count(element);
@@ -400,14 +418,14 @@ static int inferDistinctElements(Iterable<?> elements) {
    * @since 14.0
    */
   @Beta
-  public static <E> Multiset<E> union(
+  public static <E extends @Nullable Object> Multiset<E> union(
       final Multiset<? extends E> multiset1, final Multiset<? extends E> multiset2) {
     checkNotNull(multiset1);
     checkNotNull(multiset2);
 
     return new ViewMultiset<E>() {
       @Override
-      public boolean contains(@Nullable Object element) {
+      public boolean contains(@CheckForNull Object element) {
         return multiset1.contains(element) || multiset2.contains(element);
       }
 
@@ -417,7 +435,7 @@ public boolean isEmpty() {
       }
 
       @Override
-      public int count(Object element) {
+      public int count(@CheckForNull Object element) {
         return Math.max(multiset1.count(element), multiset2.count(element));
       }
 
@@ -438,6 +456,7 @@ Iterator<Entry<E>> entryIterator() {
         // TODO(lowasser): consider making the entries live views
         return new AbstractIterator<Entry<E>>() {
           @Override
+          @CheckForNull
           protected Entry<E> computeNext() {
             if (iterator1.hasNext()) {
               Entry<? extends E> entry1 = iterator1.next();
@@ -471,14 +490,14 @@ protected Entry<E> computeNext() {
    *
    * @since 2.0
    */
-  public static <E> Multiset<E> intersection(
+  public static <E extends @Nullable Object> Multiset<E> intersection(
       final Multiset<E> multiset1, final Multiset<?> multiset2) {
     checkNotNull(multiset1);
     checkNotNull(multiset2);
 
     return new ViewMultiset<E>() {
       @Override
-      public int count(Object element) {
+      public int count(@CheckForNull Object element) {
         int count1 = multiset1.count(element);
         return (count1 == 0) ? 0 : Math.min(count1, multiset2.count(element));
       }
@@ -499,6 +518,7 @@ Iterator<Entry<E>> entryIterator() {
         // TODO(lowasser): consider making the entries live views
         return new AbstractIterator<Entry<E>>() {
           @Override
+          @CheckForNull
           protected Entry<E> computeNext() {
             while (iterator1.hasNext()) {
               Entry<E> entry1 = iterator1.next();
@@ -528,7 +548,7 @@ protected Entry<E> computeNext() {
    * @since 14.0
    */
   @Beta
-  public static <E> Multiset<E> sum(
+  public static <E extends @Nullable Object> Multiset<E> sum(
       final Multiset<? extends E> multiset1, final Multiset<? extends E> multiset2) {
     checkNotNull(multiset1);
     checkNotNull(multiset2);
@@ -536,7 +556,7 @@ public static <E> Multiset<E> sum(
     // TODO(lowasser): consider making the entries live views
     return new ViewMultiset<E>() {
       @Override
-      public boolean contains(@Nullable Object element) {
+      public boolean contains(@CheckForNull Object element) {
         return multiset1.contains(element) || multiset2.contains(element);
       }
 
@@ -551,7 +571,7 @@ public int size() {
       }
 
       @Override
-      public int count(Object element) {
+      public int count(@CheckForNull Object element) {
         return multiset1.count(element) + multiset2.count(element);
       }
 
@@ -571,6 +591,7 @@ Iterator<Entry<E>> entryIterator() {
         final Iterator<? extends Entry<? extends E>> iterator2 = multiset2.entrySet().iterator();
         return new AbstractIterator<Entry<E>>() {
           @Override
+          @CheckForNull
           protected Entry<E> computeNext() {
             if (iterator1.hasNext()) {
               Entry<? extends E> entry1 = iterator1.next();
@@ -605,7 +626,7 @@ protected Entry<E> computeNext() {
    * @since 14.0
    */
   @Beta
-  public static <E> Multiset<E> difference(
+  public static <E extends @Nullable Object> Multiset<E> difference(
       final Multiset<E> multiset1, final Multiset<?> multiset2) {
     checkNotNull(multiset1);
     checkNotNull(multiset2);
@@ -613,7 +634,7 @@ public static <E> Multiset<E> difference(
     // TODO(lowasser): consider making the entries live views
     return new ViewMultiset<E>() {
       @Override
-      public int count(@Nullable Object element) {
+      public int count(@CheckForNull Object element) {
         int count1 = multiset1.count(element);
         return (count1 == 0) ? 0 : Math.max(0, count1 - multiset2.count(element));
       }
@@ -628,6 +649,7 @@ Iterator<E> elementIterator() {
         final Iterator<Entry<E>> iterator1 = multiset1.entrySet().iterator();
         return new AbstractIterator<E>() {
           @Override
+          @CheckForNull
           protected E computeNext() {
             while (iterator1.hasNext()) {
               Entry<E> entry1 = iterator1.next();
@@ -646,6 +668,7 @@ Iterator<Entry<E>> entryIterator() {
         final Iterator<Entry<E>> iterator1 = multiset1.entrySet().iterator();
         return new AbstractIterator<Entry<E>>() {
           @Override
+          @CheckForNull
           protected Entry<E> computeNext() {
             while (iterator1.hasNext()) {
               Entry<E> entry1 = iterator1.next();
@@ -709,7 +732,7 @@ public static boolean retainOccurrences(
   }
 
   /** Delegate implementation which cares about the element type. */
-  private static <E> boolean retainOccurrencesImpl(
+  private static <E extends @Nullable Object> boolean retainOccurrencesImpl(
       Multiset<E> multisetToModify, Multiset<?> occurrencesToRetain) {
     checkNotNull(multisetToModify);
     checkNotNull(occurrencesToRetain);
@@ -817,14 +840,14 @@ public static boolean removeOccurrences(
    * Implementation of the {@code equals}, {@code hashCode}, and {@code toString} methods of {@link
    * Multiset.Entry}.
    */
-  abstract static class AbstractEntry<E> implements Multiset.Entry<E> {
+  abstract static class AbstractEntry<E extends @Nullable Object> implements Multiset.Entry<E> {
     /**
      * Indicates whether an object equals this entry, following the behavior specified in {@link
      * Multiset.Entry#equals}.
      */
     @Pure
     @Override
-    public boolean equals(@Nullable Object object) {
+    public boolean equals(@CheckForNull Object object) {
       if (object instanceof Multiset.Entry) {
         Multiset.Entry<?> that = (Multiset.Entry<?>) object;
         return this.getCount() == that.getCount()
@@ -860,7 +883,7 @@ public String toString() {
   }
 
   /** An implementation of {@link Multiset#equals}. */
-  static boolean equalsImpl(Multiset<?> multiset, @Nullable Object object) {
+  static boolean equalsImpl(Multiset<?> multiset, @CheckForNull Object object) {
     if (object == multiset) {
       return true;
     }
@@ -886,7 +909,8 @@ static boolean equalsImpl(Multiset<?> multiset, @Nullable Object object) {
   }
 
   /** An implementation of {@link Multiset#addAll}. */
-  static <E> boolean addAllImpl(Multiset<E> self, Collection<? extends E> elements) {
+  static <E extends @Nullable Object> boolean addAllImpl(
+      Multiset<E> self, Collection<? extends E> elements) {
     checkNotNull(self);
     checkNotNull(elements);
     if (elements instanceof Multiset) {
@@ -899,7 +923,8 @@ static <E> boolean addAllImpl(Multiset<E> self, Collection<? extends E> elements
   }
 
   /** A specialization of {@code addAllImpl} for when {@code elements} is itself a Multiset. */
-  private static <E> boolean addAllImpl(Multiset<E> self, Multiset<? extends E> elements) {
+  private static <E extends @Nullable Object> boolean addAllImpl(
+      Multiset<E> self, Multiset<? extends E> elements) {
     if (elements.isEmpty()) {
       return false;
     }
@@ -929,7 +954,8 @@ static boolean retainAllImpl(Multiset<?> self, Collection<?> elementsToRetain) {
   }
 
   /** An implementation of {@link Multiset#setCount(Object, int)}. */
-  static <E> int setCountImpl(Multiset<E> self, E element, int count) {
+  static <E extends @Nullable Object> int setCountImpl(
+      Multiset<E> self, @ParametricNullness E element, int count) {
     checkNonnegative(count, "count");
 
     int oldCount = self.count(element);
@@ -945,7 +971,8 @@ static <E> int setCountImpl(Multiset<E> self, E element, int count) {
   }
 
   /** An implementation of {@link Multiset#setCount(Object, int, int)}. */
-  static <E> boolean setCountImpl(Multiset<E> self, E element, int oldCount, int newCount) {
+  static <E extends @Nullable Object> boolean setCountImpl(
+      Multiset<E> self, @ParametricNullness E element, int oldCount, int newCount) {
     checkNonnegative(oldCount, "oldCount");
     checkNonnegative(newCount, "newCount");
 
@@ -957,16 +984,18 @@ static <E> boolean setCountImpl(Multiset<E> self, E element, int oldCount, int n
     }
   }
 
-  static <E> Iterator<E> elementIterator(Iterator<Entry<E>> entryIterator) {
+  static <E extends @Nullable Object> Iterator<E> elementIterator(
+      Iterator<Entry<E>> entryIterator) {
     return new TransformedIterator<Entry<E>, E>(entryIterator) {
       @Override
+      @ParametricNullness
       E transform(Entry<E> entry) {
         return entry.getElement();
       }
     };
   }
 
-  abstract static class ElementSet<E> extends Sets.ImprovedAbstractSet<E> {
+  abstract static class ElementSet<E extends @Nullable Object> extends Sets.ImprovedAbstractSet<E> {
     abstract Multiset<E> multiset();
 
     @Override
@@ -975,7 +1004,7 @@ public void clear() {
     }
 
     @Override
-    public boolean contains(Object o) {
+    public boolean contains(@CheckForNull Object o) {
       return multiset().contains(o);
     }
 
@@ -993,7 +1022,7 @@ public boolean isEmpty() {
     public abstract Iterator<E> iterator();
 
     @Override
-    public boolean remove(Object o) {
+    public boolean remove(@CheckForNull Object o) {
       return multiset().remove(o, Integer.MAX_VALUE) > 0;
     }
 
@@ -1003,11 +1032,12 @@ public int size() {
     }
   }
 
-  abstract static class EntrySet<E> extends Sets.ImprovedAbstractSet<Entry<E>> {
+  abstract static class EntrySet<E extends @Nullable Object>
+      extends Sets.ImprovedAbstractSet<Entry<E>> {
     abstract Multiset<E> multiset();
 
     @Override
-    public boolean contains(@Nullable Object o) {
+    public boolean contains(@CheckForNull Object o) {
       if (o instanceof Entry) {
         /*
          * The GWT compiler wrongly issues a warning here.
@@ -1026,15 +1056,16 @@ public boolean contains(@Nullable Object o) {
     // GWT compiler warning; see contains().
     @SuppressWarnings("cast")
     @Override
-    public boolean remove(Object object) {
+    public boolean remove(@CheckForNull Object object) {
       if (object instanceof Multiset.Entry) {
         Entry<?> entry = (Entry<?>) object;
         Object element = entry.getElement();
         int entryCount = entry.getCount();
         if (entryCount != 0) {
           // Safe as long as we never add a new entry, which we won't.
-          @SuppressWarnings("unchecked")
-          Multiset<Object> multiset = (Multiset<Object>) multiset();
+          // (Presumably it can still throw CCE/NPE but only if the underlying Multiset does.)
+          @SuppressWarnings({"unchecked", "nullness"})
+          Multiset<@Nullable Object> multiset = (Multiset<@Nullable Object>) multiset();
           return multiset.setCount(element, entryCount, 0);
         }
       }
@@ -1048,14 +1079,14 @@ public void clear() {
   }
 
   /** An implementation of {@link Multiset#iterator}. */
-  static <E> Iterator<E> iteratorImpl(Multiset<E> multiset) {
+  static <E extends @Nullable Object> Iterator<E> iteratorImpl(Multiset<E> multiset) {
     return new MultisetIteratorImpl<E>(multiset, multiset.entrySet().iterator());
   }
 
-  static final class MultisetIteratorImpl<E> implements Iterator<E> {
+  static final class MultisetIteratorImpl<E extends @Nullable Object> implements Iterator<E> {
     private final Multiset<E> multiset;
     private final Iterator<Entry<E>> entryIterator;
-    private @Nullable Entry<E> currentEntry;
+    @CheckForNull private Entry<E> currentEntry;
 
     /** Count of subsequent elements equal to current element */
     private int laterCount;
@@ -1076,6 +1107,7 @@ public boolean hasNext() {
     }
 
     @Override
+    @ParametricNullness
     public E next() {
       if (!hasNext()) {
         throw new NoSuchElementException();
@@ -1086,7 +1118,11 @@ public E next() {
       }
       laterCount--;
       canRemove = true;
-      return currentEntry.getElement();
+      /*
+       * requireNonNull is safe because laterCount starts at 0, forcing us to initialize
+       * currentEntry above. After that, we never clear it.
+       */
+      return requireNonNull(currentEntry).getElement();
     }
 
     @Override
@@ -1095,14 +1131,18 @@ public void remove() {
       if (totalCount == 1) {
         entryIterator.remove();
       } else {
-        multiset.remove(currentEntry.getElement());
+        /*
+         * requireNonNull is safe because canRemove is set to true only after we initialize
+         * currentEntry (which we never subsequently clear).
+         */
+        multiset.remove(requireNonNull(currentEntry).getElement());
       }
       totalCount--;
       canRemove = false;
     }
   }
 
-  static <E> Spliterator<E> spliteratorImpl(Multiset<E> multiset) {
+  static <E extends @Nullable Object> Spliterator<E> spliteratorImpl(Multiset<E> multiset) {
     Spliterator<Entry<E>> entrySpliterator = multiset.entrySet().spliterator();
     return CollectSpliterators.flatMap(
         entrySpliterator,
@@ -1123,7 +1163,7 @@ static int linearTimeSizeImpl(Multiset<?> multiset) {
   }
 
   /** Used to avoid http://bugs.sun.com/view_bug.do?bug_id=6558557 */
-  static <T> Multiset<T> cast(Iterable<T> iterable) {
+  static <T extends @Nullable Object> Multiset<T> cast(Iterable<T> iterable) {
     return (Multiset<T>) iterable;
   }
 
@@ -1153,7 +1193,8 @@ public int compare(Entry<?> entry1, Entry<?> entry2) {
    * An {@link AbstractMultiset} with additional default implementations, some of them linear-time
    * implementations in terms of {@code elementSet} and {@code entrySet}.
    */
-  private abstract static class ViewMultiset<E> extends AbstractMultiset<E> {
+  private abstract static class ViewMultiset<E extends @Nullable Object>
+      extends AbstractMultiset<E> {
     @Override
     public int size() {
       return linearTimeSizeImpl(this);
diff --git a/guava/src/com/google/common/collect/MutableClassToInstanceMap.java b/guava/src/com/google/common/collect/MutableClassToInstanceMap.java
index a9615edf5a3c..f0c54718382d 100644
--- a/guava/src/com/google/common/collect/MutableClassToInstanceMap.java
+++ b/guava/src/com/google/common/collect/MutableClassToInstanceMap.java
@@ -28,6 +28,7 @@
 import java.util.Map;
 import java.util.Set;
 import java.util.Spliterator;
+import javax.annotation.CheckForNull;
 import org.checkerframework.checker.nullness.qual.Nullable;
 import org.checkerframework.framework.qual.AnnotatedFor;
 
@@ -36,15 +37,19 @@
  * ImmutableClassToInstanceMap}.
  *
  * <p>See the Guava User Guide article on <a href=
- * "https://github.com/google/guava/wiki/NewCollectionTypesExplained#classtoinstancemap"> {@code
+ * "https://github.com/google/guava/wiki/NewCollectionTypesExplained#classtoinstancemap">{@code
  * ClassToInstanceMap}</a>.
  *
+ * <p>This implementation <i>does</i> support null values, despite how it is annotated; see
+ * discussion at {@link ClassToInstanceMap}.
+ *
  * @author Kevin Bourrillion
  * @since 2.0
  */
 @GwtIncompatible
 @SuppressWarnings("serial") // using writeReplace instead of standard serialization
 @AnnotatedFor({"nullness"})
+@ElementTypesAreNonnullByDefault
 public final class MutableClassToInstanceMap<B> extends ForwardingMap<Class<? extends B>, B>
     implements ClassToInstanceMap<B>, Serializable {
 
@@ -122,11 +127,20 @@ Entry<Class<? extends B>, B> transform(Entry<Class<? extends B>, B> from) {
 
       @Override
       public Object[] toArray() {
-        return standardToArray();
+        /*
+         * standardToArray returns `@Nullable Object[]` rather than `Object[]` but only because it
+         * can be used with collections that may contain null. This collection is a collection of
+         * non-null Entry objects (Entry objects that might contain null values but are not
+         * themselves null), so we can treat it as a plain `Object[]`.
+         */
+        @SuppressWarnings("nullness")
+        Object[] result = standardToArray();
+        return result;
       }
 
       @Override
-      public <T> T[] toArray(T[] array) {
+      @SuppressWarnings("nullness") // b/192354773 in our checker affects toArray declarations
+      public <T extends @Nullable Object> T[] toArray(T[] array) {
         return standardToArray(array);
       }
     };
@@ -134,6 +148,7 @@ public <T> T[] toArray(T[] array) {
 
   @Override
   @CanIgnoreReturnValue
+  @CheckForNull
   public B put(Class<? extends B> key, B value) {
     return super.put(key, cast(key, value));
   }
@@ -149,17 +164,20 @@ public void putAll(Map<? extends Class<? extends B>, ? extends B> map) {
 
   @CanIgnoreReturnValue
   @Override
+  @CheckForNull
   public <T extends B> T putInstance(Class<T> type, T value) {
     return cast(type, put(type, value));
   }
 
   @Override
+  @CheckForNull
   public <T extends B> T getInstance(Class<T> type) {
     return cast(type, get(type));
   }
 
   @CanIgnoreReturnValue
-  private static <B, T extends B> T cast(Class<T> type, @Nullable B value) {
+  @CheckForNull
+  private static <B, T extends B> T cast(Class<T> type, @CheckForNull B value) {
     return Primitives.wrap(type).cast(value);
   }
 
diff --git a/guava/src/com/google/common/collect/NaturalOrdering.java b/guava/src/com/google/common/collect/NaturalOrdering.java
index 41fe22c11f83..20af68fae52f 100644
--- a/guava/src/com/google/common/collect/NaturalOrdering.java
+++ b/guava/src/com/google/common/collect/NaturalOrdering.java
@@ -20,6 +20,7 @@
 
 import com.google.common.annotations.GwtCompatible;
 import java.io.Serializable;
+import javax.annotation.CheckForNull;
 import org.checkerframework.checker.nullness.qual.MonotonicNonNull;
 import org.checkerframework.checker.nullness.qual.Nullable;
 import org.checkerframework.dataflow.qual.Pure;
@@ -29,40 +30,41 @@
 @AnnotatedFor({"nullness"})
 @GwtCompatible(serializable = true)
 @SuppressWarnings({"unchecked", "rawtypes"}) // TODO(kevinb): the right way to explain this??
-final class NaturalOrdering extends Ordering<Comparable> implements Serializable {
+@ElementTypesAreNonnullByDefault
+final class NaturalOrdering extends Ordering<Comparable<?>> implements Serializable {
   static final NaturalOrdering INSTANCE = new NaturalOrdering();
 
-  private transient @Nullable Ordering<Comparable> nullsFirst;
-  private transient @Nullable Ordering<Comparable> nullsLast;
+  @CheckForNull private transient Ordering<@Nullable Comparable<?>> nullsFirst;
+  @CheckForNull private transient Ordering<@Nullable Comparable<?>> nullsLast;
 
   @Pure
   @Override
-  public int compare(Comparable left, Comparable right) {
+  public int compare(Comparable<?> left, Comparable<?> right) {
     checkNotNull(left); // for GWT
     checkNotNull(right);
-    return left.compareTo(right);
+    return ((Comparable<Object>) left).compareTo(right);
   }
 
   @Override
-  public <S extends Comparable> Ordering<S> nullsFirst() {
-    Ordering<Comparable> result = nullsFirst;
+  public <S extends Comparable<?>> Ordering<@Nullable S> nullsFirst() {
+    Ordering<@Nullable Comparable<?>> result = nullsFirst;
     if (result == null) {
-      result = nullsFirst = super.nullsFirst();
+      result = nullsFirst = super.<Comparable<?>>nullsFirst();
     }
-    return (Ordering<S>) result;
+    return (Ordering<@Nullable S>) result;
   }
 
   @Override
-  public <S extends Comparable> Ordering<S> nullsLast() {
-    Ordering<Comparable> result = nullsLast;
+  public <S extends Comparable<?>> Ordering<@Nullable S> nullsLast() {
+    Ordering<@Nullable Comparable<?>> result = nullsLast;
     if (result == null) {
-      result = nullsLast = super.nullsLast();
+      result = nullsLast = super.<Comparable<?>>nullsLast();
     }
-    return (Ordering<S>) result;
+    return (Ordering<@Nullable S>) result;
   }
 
   @Override
-  public <S extends Comparable> Ordering<S> reverse() {
+  public <S extends Comparable<?>> Ordering<S> reverse() {
     return (Ordering<S>) ReverseNaturalOrdering.INSTANCE;
   }
 
diff --git a/guava/src/com/google/common/collect/NullnessCasts.java b/guava/src/com/google/common/collect/NullnessCasts.java
new file mode 100644
index 000000000000..4f894dbd3139
--- /dev/null
+++ b/guava/src/com/google/common/collect/NullnessCasts.java
@@ -0,0 +1,68 @@
+/*
+ * Copyright (C) 2021 The Guava Authors
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file except
+ * in compliance with the License. You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software distributed under the License
+ * is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express
+ * or implied. See the License for the specific language governing permissions and limitations under
+ * the License.
+ */
+
+package com.google.common.collect;
+
+import com.google.common.annotations.GwtCompatible;
+import javax.annotation.CheckForNull;
+import org.checkerframework.checker.nullness.qual.Nullable;
+
+/** A utility method to perform unchecked casts to suppress errors produced by nullness analyses. */
+@GwtCompatible
+@ElementTypesAreNonnullByDefault
+final class NullnessCasts {
+  /**
+   * Accepts a {@code @Nullable T} and returns a plain {@code T}, without performing any check that
+   * that conversion is safe.
+   *
+   * <p>This method is intended to help with usages of type parameters that have {@linkplain
+   * ParametricNullness parametric nullness}. If a type parameter instead ranges over only non-null
+   * types (or if the type is a non-variable type, like {@code String}), then code should almost
+   * never use this method, preferring instead to call {@code requireNonNull} so as to benefit from
+   * its runtime check.
+   *
+   * <p>An example use case for this method is in implementing an {@code Iterator<T>} whose {@code
+   * next} field is lazily initialized. The type of that field would be {@code @Nullable T}, and the
+   * code would be responsible for populating a "real" {@code T} (which might still be the value
+   * {@code null}!) before returning it to callers. Depending on how the code is structured, a
+   * nullness analysis might not understand that the field has been populated. To avoid that problem
+   * without having to add {@code @SuppressWarnings}, the code can call this method.
+   *
+   * <p>Why <i>not</i> just add {@code SuppressWarnings}? The problem is that this method is
+   * typically useful for {@code return} statements. That leaves the code with two options: Either
+   * add the suppression to the whole method (which turns off checking for a large section of code),
+   * or extract a variable, and put the suppression on that. However, a local variable typically
+   * doesn't work: Because nullness analyses typically infer the nullness of local variables,
+   * there's no way to assign a {@code @Nullable T} to a field {@code T foo;} and instruct the
+   * analysis that that means "plain {@code T}" rather than the inferred type {@code @Nullable T}.
+   * (Even if supported added {@code @NonNull}, that would not help, since the problem case
+   * addressed by this method is the case in which {@code T} has parametric nullness -- and thus its
+   * value may be legitimately {@code null}.)
+   */
+  @ParametricNullness
+  @SuppressWarnings("nullness")
+  static <T extends @Nullable Object> T uncheckedCastNullableTToT(@CheckForNull T t) {
+    return t;
+  }
+
+  /** Returns {@code null} as any type, even one that does not include {@code null}. */
+  @SuppressWarnings({"nullness", "TypeParameterUnusedInFormals", "ReturnMissingNullable"})
+  // The warnings are legitimate. Each time we use this method, we document why.
+  @ParametricNullness
+  static <T extends @Nullable Object> T unsafeNull() {
+    return null;
+  }
+
+  private NullnessCasts() {}
+}
diff --git a/guava/src/com/google/common/collect/NullsFirstOrdering.java b/guava/src/com/google/common/collect/NullsFirstOrdering.java
index 0b3757290a14..cceac05c539c 100644
--- a/guava/src/com/google/common/collect/NullsFirstOrdering.java
+++ b/guava/src/com/google/common/collect/NullsFirstOrdering.java
@@ -18,6 +18,7 @@
 
 import com.google.common.annotations.GwtCompatible;
 import java.io.Serializable;
+import javax.annotation.CheckForNull;
 import org.checkerframework.checker.nullness.qual.Nullable;
 import org.checkerframework.dataflow.qual.Pure;
 import org.checkerframework.framework.qual.AnnotatedFor;
@@ -25,7 +26,9 @@
 /** An ordering that treats {@code null} as less than all other values. */
 @AnnotatedFor({"nullness"})
 @GwtCompatible(serializable = true)
-final class NullsFirstOrdering<T> extends Ordering<T> implements Serializable {
+@ElementTypesAreNonnullByDefault
+final class NullsFirstOrdering<T extends @Nullable Object> extends Ordering<@Nullable T>
+    implements Serializable {
   final Ordering<? super T> ordering;
 
   NullsFirstOrdering(Ordering<? super T> ordering) {
@@ -34,7 +37,7 @@ final class NullsFirstOrdering<T> extends Ordering<T> implements Serializable {
 
   @Pure
   @Override
-  public int compare(@Nullable T left, @Nullable T right) {
+  public int compare(@CheckForNull T left, @CheckForNull T right) {
     if (left == right) {
       return 0;
     }
@@ -48,25 +51,26 @@ public int compare(@Nullable T left, @Nullable T right) {
   }
 
   @Override
-  public <S extends T> Ordering<S> reverse() {
+  @SuppressWarnings("nullness") // should be safe, but not sure if we can avoid the warning
+  public <S extends @Nullable T> Ordering<S> reverse() {
     // ordering.reverse() might be optimized, so let it do its thing
     return ordering.reverse().nullsLast();
   }
 
   @SuppressWarnings("unchecked") // still need the right way to explain this
   @Override
-  public <S extends T> Ordering<S> nullsFirst() {
-    return (Ordering<S>) this;
+  public <S extends T> Ordering<@Nullable S> nullsFirst() {
+    return (Ordering<@Nullable S>) this;
   }
 
   @Override
-  public <S extends T> Ordering<S> nullsLast() {
-    return ordering.nullsLast();
+  public <S extends T> Ordering<@Nullable S> nullsLast() {
+    return ordering.<S>nullsLast();
   }
 
   @Pure
   @Override
-  public boolean equals(@Nullable Object object) {
+  public boolean equals(@CheckForNull Object object) {
     if (object == this) {
       return true;
     }
diff --git a/guava/src/com/google/common/collect/NullsLastOrdering.java b/guava/src/com/google/common/collect/NullsLastOrdering.java
index ea92942c0b3f..f80b33a6fcbf 100644
--- a/guava/src/com/google/common/collect/NullsLastOrdering.java
+++ b/guava/src/com/google/common/collect/NullsLastOrdering.java
@@ -18,6 +18,7 @@
 
 import com.google.common.annotations.GwtCompatible;
 import java.io.Serializable;
+import javax.annotation.CheckForNull;
 import org.checkerframework.checker.nullness.qual.Nullable;
 import org.checkerframework.dataflow.qual.Pure;
 import org.checkerframework.framework.qual.AnnotatedFor;
@@ -25,7 +26,9 @@
 /** An ordering that treats {@code null} as greater than all other values. */
 @AnnotatedFor({"nullness"})
 @GwtCompatible(serializable = true)
-final class NullsLastOrdering<T> extends Ordering<T> implements Serializable {
+@ElementTypesAreNonnullByDefault
+final class NullsLastOrdering<T extends @Nullable Object> extends Ordering<@Nullable T>
+    implements Serializable {
   final Ordering<? super T> ordering;
 
   NullsLastOrdering(Ordering<? super T> ordering) {
@@ -34,7 +37,7 @@ final class NullsLastOrdering<T> extends Ordering<T> implements Serializable {
 
   @Pure
   @Override
-  public int compare(@Nullable T left, @Nullable T right) {
+  public int compare(@CheckForNull T left, @CheckForNull T right) {
     if (left == right) {
       return 0;
     }
@@ -48,25 +51,26 @@ public int compare(@Nullable T left, @Nullable T right) {
   }
 
   @Override
-  public <S extends T> Ordering<S> reverse() {
+  @SuppressWarnings("nullness") // should be safe, but not sure if we can avoid the warning
+  public <S extends @Nullable T> Ordering<S> reverse() {
     // ordering.reverse() might be optimized, so let it do its thing
     return ordering.reverse().nullsFirst();
   }
 
   @Override
-  public <S extends T> Ordering<S> nullsFirst() {
-    return ordering.nullsFirst();
+  public <S extends T> Ordering<@Nullable S> nullsFirst() {
+    return ordering.<S>nullsFirst();
   }
 
   @SuppressWarnings("unchecked") // still need the right way to explain this
   @Override
-  public <S extends T> Ordering<S> nullsLast() {
-    return (Ordering<S>) this;
+  public <S extends T> Ordering<@Nullable S> nullsLast() {
+    return (Ordering<@Nullable S>) this;
   }
 
   @Pure
   @Override
-  public boolean equals(@Nullable Object object) {
+  public boolean equals(@CheckForNull Object object) {
     if (object == this) {
       return true;
     }
diff --git a/guava/src/com/google/common/collect/ObjectArrays.java b/guava/src/com/google/common/collect/ObjectArrays.java
index a0a1db48067f..f229ee379b0a 100644
--- a/guava/src/com/google/common/collect/ObjectArrays.java
+++ b/guava/src/com/google/common/collect/ObjectArrays.java
@@ -35,6 +35,7 @@
  */
 @AnnotatedFor({"nullness"})
 @GwtCompatible(emulated = true)
+@ElementTypesAreNonnullByDefault
 public final class ObjectArrays {
 
   private ObjectArrays() {}
@@ -57,7 +58,7 @@ public static <T> T[] newArray(Class<T> type, int length) {
    * @param reference any array of the desired type
    * @param length the length of the new array
    */
-  public static <T> T[] newArray(T[] reference, int length) {
+  public static <T extends @Nullable Object> T[] newArray(T[] reference, int length) {
     return Platform.newArray(reference, length);
   }
 
@@ -84,7 +85,7 @@ public static <T> T[] concat(T[] first, T[] second, Class<T> type) {
    * @return an array whose size is one larger than {@code array}, with {@code element} occupying
    *     the first position, and the elements of {@code array} occupying the remaining elements.
    */
-  public static <T> T[] concat(@Nullable T element, T[] array) {
+  public static <T extends @Nullable Object> T[] concat(@ParametricNullness T element, T[] array) {
     T[] result = newArray(array, array.length + 1);
     result[0] = element;
     System.arraycopy(array, 0, result, 1, array.length);
@@ -99,7 +100,7 @@ public static <T> T[] concat(@Nullable T element, T[] array) {
    * @return an array whose size is one larger than {@code array}, with the same contents as {@code
    *     array}, plus {@code element} occupying the last position.
    */
-  public static <T> T[] concat(T[] array, @Nullable T element) {
+  public static <T extends @Nullable Object> T[] concat(T[] array, @ParametricNullness T element) {
     T[] result = Arrays.copyOf(array, array.length + 1);
     result[array.length] = element;
     return result;
@@ -126,15 +127,15 @@ public static <T> T[] concat(T[] array, @Nullable T element) {
    * @throws ArrayStoreException if the runtime type of the specified array is not a supertype of
    *     the runtime type of every element in the specified collection
    */
-  // Annotation here is not technically correct; see note on toArray
-  static <T> T[] toArrayImpl(Collection<?> c, @Nullable T[] array) {
+  static <T extends @Nullable Object> T[] toArrayImpl(Collection<?> c, T[] array) {
     int size = c.size();
     if (array.length < size) {
       array = newArray(array, size);
     }
     fillArray(c, array);
     if (array.length > size) {
-      array[size] = null;
+      @Nullable Object[] unsoundlyCovariantArray = array;
+      unsoundlyCovariantArray[size] = null;
     }
     return array;
   }
@@ -150,12 +151,14 @@ static <T> T[] toArrayImpl(Collection<?> c, @Nullable T[] array) {
    * collection is set to {@code null}. This is useful in determining the length of the collection
    * <i>only</i> if the caller knows that the collection does not contain any null elements.
    */
-  static <T> T[] toArrayImpl(Object[] src, int offset, int len, T[] dst) {
+  static <T extends @Nullable Object> T[] toArrayImpl(
+      @Nullable Object[] src, int offset, int len, T[] dst) {
     checkPositionIndexes(offset, offset + len, src.length);
     if (dst.length < len) {
       dst = newArray(dst, len);
     } else if (dst.length > len) {
-      dst[len] = null;
+      @Nullable Object[] unsoundlyCovariantArray = dst;
+      unsoundlyCovariantArray[len] = null;
     }
     System.arraycopy(src, offset, dst, 0, len);
     return dst;
@@ -181,12 +184,12 @@ static <T> T[] toArrayImpl(Object[] src, int offset, int len, T[] dst) {
    * Returns a copy of the specified subrange of the specified array that is literally an Object[],
    * and not e.g. a {@code String[]}.
    */
-  static Object[] copyAsObjectArray(Object[] elements, int offset, int length) {
+  static @Nullable Object[] copyAsObjectArray(@Nullable Object[] elements, int offset, int length) {
     checkPositionIndexes(offset, offset + length, elements.length);
     if (length == 0) {
       return new Object[0];
     }
-    Object[] result = new Object[length];
+    @Nullable Object[] result = new Object[length];
     System.arraycopy(elements, offset, result, 0, length);
     return result;
   }
diff --git a/guava/src/com/google/common/collect/Ordering.java b/guava/src/com/google/common/collect/Ordering.java
index b3c536b60d98..4085067fb2d9 100644
--- a/guava/src/com/google/common/collect/Ordering.java
+++ b/guava/src/com/google/common/collect/Ordering.java
@@ -38,6 +38,7 @@
 import java.util.TreeSet;
 import java.util.concurrent.ConcurrentMap;
 import java.util.concurrent.atomic.AtomicInteger;
+import javax.annotation.CheckForNull;
 import org.checkerframework.checker.nullness.qual.Nullable;
 import org.checkerframework.dataflow.qual.Pure;
 import org.checkerframework.framework.qual.AnnotatedFor;
@@ -147,7 +148,8 @@
  */
 @AnnotatedFor({"nullness"})
 @GwtCompatible
-public abstract class Ordering<T> implements Comparator<T> {
+@ElementTypesAreNonnullByDefault
+public abstract class Ordering<T extends @Nullable Object> implements Comparator<T> {
   // Natural order
 
   /**
@@ -181,7 +183,7 @@ public static <C extends Comparable> Ordering<C> natural() {
    *     wraps that comparator
    */
   @GwtCompatible(serializable = true)
-  public static <T> Ordering<T> from(Comparator<T> comparator) {
+  public static <T extends @Nullable Object> Ordering<T> from(Comparator<T> comparator) {
     return (comparator instanceof Ordering)
         ? (Ordering<T>) comparator
         : new ComparatorOrdering<T>(comparator);
@@ -194,7 +196,7 @@ public static <T> Ordering<T> from(Comparator<T> comparator) {
    */
   @GwtCompatible(serializable = true)
   @Deprecated
-  public static <T> Ordering<T> from(Ordering<T> ordering) {
+  public static <T extends @Nullable Object> Ordering<T> from(Ordering<T> ordering) {
     return checkNotNull(ordering);
   }
 
@@ -281,7 +283,7 @@ public static <T> Ordering<T> explicit(T leastValue, T... remainingValuesInOrder
    */
   @GwtCompatible(serializable = true)
   @SuppressWarnings("unchecked")
-  public static Ordering<Object> allEqual() {
+  public static Ordering<@Nullable Object> allEqual() {
     return AllEqualOrdering.INSTANCE;
   }
 
@@ -314,16 +316,16 @@ public static Ordering<Object> usingToString() {
    * @since 2.0
    */
   // TODO(kevinb): copy to Comparators, etc.
-  public static Ordering<Object> arbitrary() {
+  public static Ordering<@Nullable Object> arbitrary() {
     return ArbitraryOrderingHolder.ARBITRARY_ORDERING;
   }
 
   private static class ArbitraryOrderingHolder {
-    static final Ordering<Object> ARBITRARY_ORDERING = new ArbitraryOrdering();
+    static final Ordering<@Nullable Object> ARBITRARY_ORDERING = new ArbitraryOrdering();
   }
 
   @VisibleForTesting
-  static class ArbitraryOrdering extends Ordering<Object> {
+  static class ArbitraryOrdering extends Ordering<@Nullable Object> {
 
     private final AtomicInteger counter = new AtomicInteger(0);
     private final ConcurrentMap<Object, Integer> uids =
@@ -345,7 +347,7 @@ private Integer getUid(Object obj) {
     }
 
     @Override
-    public int compare(Object left, Object right) {
+    public int compare(@CheckForNull Object left, @CheckForNull Object right) {
       if (left == right) {
         return 0;
       } else if (left == null) {
@@ -448,7 +450,7 @@ public <S extends T> Ordering<S> reverse() {
    * can omit the comparator if it is the natural order).
    */
   @GwtCompatible(serializable = true)
-  public <F> Ordering<F> onResultOf(Function<F, ? extends T> function) {
+  public <F extends @Nullable Object> Ordering<F> onResultOf(Function<F, ? extends T> function) {
     return new ByFunctionOrdering<>(function, this);
   }
 
@@ -494,7 +496,8 @@ public <U extends T> Ordering<U> compound(Comparator<? super U> secondaryCompara
    * @param comparators the comparators to try in order
    */
   @GwtCompatible(serializable = true)
-  public static <T> Ordering<T> compound(Iterable<? extends Comparator<? super T>> comparators) {
+  public static <T extends @Nullable Object> Ordering<T> compound(
+      Iterable<? extends Comparator<? super T>> comparators) {
     return new CompoundOrdering<T>(comparators);
   }
 
@@ -530,10 +533,9 @@ public <S extends T> Ordering<Iterable<S>> lexicographical() {
 
   // Regular instance methods
 
-  // Override to add @Nullable
   @CanIgnoreReturnValue // TODO(kak): Consider removing this
   @Override
-  public abstract int compare(@Nullable T left, @Nullable T right);
+  public abstract int compare(@ParametricNullness T left, @ParametricNullness T right);
 
   /**
    * Returns the least of the specified values according to this ordering. If there are multiple
@@ -549,6 +551,7 @@ public <S extends T> Ordering<Iterable<S>> lexicographical() {
    *     ordering.
    * @since 11.0
    */
+  @ParametricNullness
   public <E extends T> E min(Iterator<E> iterator) {
     // let this throw NoSuchElementException as necessary
     E minSoFar = iterator.next();
@@ -574,6 +577,7 @@ public <E extends T> E min(Iterator<E> iterator) {
    * @throws ClassCastException if the parameters are not <i>mutually comparable</i> under this
    *     ordering.
    */
+  @ParametricNullness
   public <E extends T> E min(Iterable<E> iterable) {
     return min(iterable.iterator());
   }
@@ -593,7 +597,8 @@ public <E extends T> E min(Iterable<E> iterable) {
    * @throws ClassCastException if the parameters are not <i>mutually comparable</i> under this
    *     ordering.
    */
-  public <E extends T> E min(@Nullable E a, @Nullable E b) {
+  @ParametricNullness
+  public <E extends T> E min(@ParametricNullness E a, @ParametricNullness E b) {
     return (compare(a, b) <= 0) ? a : b;
   }
 
@@ -611,7 +616,9 @@ public <E extends T> E min(@Nullable E a, @Nullable E b) {
    * @throws ClassCastException if the parameters are not <i>mutually comparable</i> under this
    *     ordering.
    */
-  public <E extends T> E min(@Nullable E a, @Nullable E b, @Nullable E c, E... rest) {
+  @ParametricNullness
+  public <E extends T> E min(
+      @ParametricNullness E a, @ParametricNullness E b, @ParametricNullness E c, E... rest) {
     E minSoFar = min(min(a, b), c);
 
     for (E r : rest) {
@@ -635,6 +642,7 @@ public <E extends T> E min(@Nullable E a, @Nullable E b, @Nullable E c, E... res
    *     ordering.
    * @since 11.0
    */
+  @ParametricNullness
   public <E extends T> E max(Iterator<E> iterator) {
     // let this throw NoSuchElementException as necessary
     E maxSoFar = iterator.next();
@@ -660,6 +668,7 @@ public <E extends T> E max(Iterator<E> iterator) {
    * @throws ClassCastException if the parameters are not <i>mutually comparable</i> under this
    *     ordering.
    */
+  @ParametricNullness
   public <E extends T> E max(Iterable<E> iterable) {
     return max(iterable.iterator());
   }
@@ -679,7 +688,8 @@ public <E extends T> E max(Iterable<E> iterable) {
    * @throws ClassCastException if the parameters are not <i>mutually comparable</i> under this
    *     ordering.
    */
-  public <E extends T> E max(@Nullable E a, @Nullable E b) {
+  @ParametricNullness
+  public <E extends T> E max(@ParametricNullness E a, @ParametricNullness E b) {
     return (compare(a, b) >= 0) ? a : b;
   }
 
@@ -697,7 +707,9 @@ public <E extends T> E max(@Nullable E a, @Nullable E b) {
    * @throws ClassCastException if the parameters are not <i>mutually comparable</i> under this
    *     ordering.
    */
-  public <E extends T> E max(@Nullable E a, @Nullable E b, @Nullable E c, E... rest) {
+  @ParametricNullness
+  public <E extends T> E max(
+      @ParametricNullness E a, @ParametricNullness E b, @ParametricNullness E c, E... rest) {
     E maxSoFar = max(max(a, b), c);
 
     for (E r : rest) {
@@ -862,6 +874,7 @@ public <E extends T> List<E> sortedCopy(Iterable<E> elements) {
    * @since 3.0
    */
   // TODO(kevinb): rerun benchmarks including new options
+  @SuppressWarnings("nullness") // unsafe, but there's not much we can do about it now
   public <E extends T> ImmutableList<E> immutableSortedCopy(Iterable<E> elements) {
     return ImmutableList.sortedCopyOf(this, elements);
   }
@@ -925,7 +938,8 @@ public boolean isStrictlyOrdered(Iterable<? extends T> iterable) {
    * @deprecated Use {@link Collections#binarySearch(List, Object, Comparator)} directly.
    */
   @Deprecated
-  public int binarySearch(List<? extends T> sortedList, @Nullable T key) {
+  public int binarySearch(
+      List<? extends T> sortedList, @ParametricNullness T key) {
     return Collections.binarySearch(sortedList, key, this);
   }
 
diff --git a/guava/src/com/google/common/collect/ParametricNullness.java b/guava/src/com/google/common/collect/ParametricNullness.java
new file mode 100644
index 000000000000..94b1bcd3aaa2
--- /dev/null
+++ b/guava/src/com/google/common/collect/ParametricNullness.java
@@ -0,0 +1,52 @@
+/*
+ * Copyright (C) 2021 The Guava Authors
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package com.google.common.collect;
+
+import static java.lang.annotation.ElementType.FIELD;
+import static java.lang.annotation.ElementType.METHOD;
+import static java.lang.annotation.ElementType.PARAMETER;
+import static java.lang.annotation.RetentionPolicy.RUNTIME;
+
+import com.google.common.annotations.GwtCompatible;
+import java.lang.annotation.Retention;
+import java.lang.annotation.Target;
+
+/**
+ * Marks a "top-level" type-variable usage as the closest we can get to "non-nullable when
+ * non-nullable; nullable when nullable" (like the Android <a
+ * href="https://android.googlesource.com/platform/libcore/+/master/luni/src/main/java/libcore/util/NullFromTypeParam.java">{@code
+ * NullFromTypeParam}</a>).
+ *
+ * <p>Consumers of this annotation include:
+ *
+ * <ul>
+ *   <li>Kotlin, for which it makes the type-variable usage (a) a Kotlin platform type when the type
+ *       argument is non-nullable and (b) nullable when the type argument is nullable. We use this
+ *       to "undo" {@link ElementTypesAreNonnullByDefault}.
+ *   <li><a href="https://developers.google.com/j2objc">J2ObjC</a>
+ *   <li>{@code NullPointerTester}, at least in the Android backport (where the type-use annotations
+ *       {@code NullPointerTester} would need are not available) and in case of <a
+ *       href="https://bugs.openjdk.java.net/browse/JDK-8202469">JDK-8202469</a>
+ * </ul>
+ *
+ */
+@GwtCompatible
+@Retention(RUNTIME)
+@Target({FIELD, METHOD, PARAMETER})
+@javax.annotation.meta.TypeQualifierNickname
+@javax.annotation.Nonnull(when = javax.annotation.meta.When.UNKNOWN)
+@interface ParametricNullness {}
diff --git a/guava/src/com/google/common/collect/PeekingIterator.java b/guava/src/com/google/common/collect/PeekingIterator.java
index 9f37b160aa72..1e82ddbf942e 100644
--- a/guava/src/com/google/common/collect/PeekingIterator.java
+++ b/guava/src/com/google/common/collect/PeekingIterator.java
@@ -21,13 +21,14 @@
 import com.google.errorprone.annotations.DoNotMock;
 import java.util.Iterator;
 import java.util.NoSuchElementException;
+import org.checkerframework.checker.nullness.qual.Nullable;
 import org.checkerframework.framework.qual.AnnotatedFor;
 
 /**
  * An iterator that supports a one-element lookahead while iterating.
  *
  * <p>See the Guava User Guide article on <a href=
- * "https://github.com/google/guava/wiki/CollectionHelpersExplained#peekingiterator"> {@code
+ * "https://github.com/google/guava/wiki/CollectionHelpersExplained#peekingiterator">{@code
  * PeekingIterator}</a>.
  *
  * @author Mick Killianey
@@ -36,7 +37,8 @@
 @DoNotMock("Use Iterators.peekingIterator")
 @GwtCompatible
 @AnnotatedFor({"nullness"})
-public interface PeekingIterator<E> extends Iterator<E> {
+@ElementTypesAreNonnullByDefault
+public interface PeekingIterator<E extends @Nullable Object> extends Iterator<E> {
   /**
    * Returns the next element in the iteration, without advancing the iteration.
    *
@@ -46,6 +48,7 @@ public interface PeekingIterator<E> extends Iterator<E> {
    * @throws NoSuchElementException if the iteration has no more elements according to {@link
    *     #hasNext()}
    */
+  @ParametricNullness
   E peek();
 
   /**
@@ -56,6 +59,7 @@ public interface PeekingIterator<E> extends Iterator<E> {
    */
   @CanIgnoreReturnValue
   @Override
+  @ParametricNullness
   E next();
 
   /**
diff --git a/guava/src/com/google/common/collect/Platform.java b/guava/src/com/google/common/collect/Platform.java
index 3d16be5e2c74..8ee4b651cd5c 100644
--- a/guava/src/com/google/common/collect/Platform.java
+++ b/guava/src/com/google/common/collect/Platform.java
@@ -21,6 +21,8 @@
 import java.util.Arrays;
 import java.util.Map;
 import java.util.Set;
+import java.util.concurrent.ConcurrentHashMap;
+import org.checkerframework.checker.nullness.qual.Nullable;
 import org.checkerframework.framework.qual.AnnotatedFor;
 
 /**
@@ -30,12 +32,14 @@
  */
 @AnnotatedFor({"nullness"})
 @GwtCompatible(emulated = true)
+@ElementTypesAreNonnullByDefault
 final class Platform {
   private static final java.util.logging.Logger logger =
       java.util.logging.Logger.getLogger(Platform.class.getName());
 
   /** Returns the platform preferred implementation of a map based on a hash table. */
-  static <K, V> Map<K, V> newHashMapWithExpectedSize(int expectedSize) {
+  static <K extends @Nullable Object, V extends @Nullable Object>
+      Map<K, V> newHashMapWithExpectedSize(int expectedSize) {
     return Maps.newHashMapWithExpectedSize(expectedSize);
   }
 
@@ -43,20 +47,26 @@ static <K, V> Map<K, V> newHashMapWithExpectedSize(int expectedSize) {
    * Returns the platform preferred implementation of an insertion ordered map based on a hash
    * table.
    */
-  static <K, V> Map<K, V> newLinkedHashMapWithExpectedSize(int expectedSize) {
+  static <K extends @Nullable Object, V extends @Nullable Object>
+      Map<K, V> newLinkedHashMapWithExpectedSize(int expectedSize) {
     return Maps.newLinkedHashMapWithExpectedSize(expectedSize);
   }
 
   /** Returns the platform preferred implementation of a set based on a hash table. */
-  static <E> Set<E> newHashSetWithExpectedSize(int expectedSize) {
+  static <E extends @Nullable Object> Set<E> newHashSetWithExpectedSize(int expectedSize) {
     return Sets.newHashSetWithExpectedSize(expectedSize);
   }
 
+  /** Returns the platform preferred implementation of a thread-safe hash set. */
+  static <E> Set<E> newConcurrentHashSet() {
+    return ConcurrentHashMap.newKeySet();
+  }
+
   /**
    * Returns the platform preferred implementation of an insertion ordered set based on a hash
    * table.
    */
-  static <E> Set<E> newLinkedHashSetWithExpectedSize(int expectedSize) {
+  static <E extends @Nullable Object> Set<E> newLinkedHashSetWithExpectedSize(int expectedSize) {
     return Sets.newLinkedHashSetWithExpectedSize(expectedSize);
   }
 
@@ -64,7 +74,8 @@ static <E> Set<E> newLinkedHashSetWithExpectedSize(int expectedSize) {
    * Returns the platform preferred map implementation that preserves insertion order when used only
    * for insertions.
    */
-  static <K, V> Map<K, V> preservesInsertionOrderOnPutsMap() {
+  static <K extends @Nullable Object, V extends @Nullable Object>
+      Map<K, V> preservesInsertionOrderOnPutsMap() {
     return Maps.newLinkedHashMap();
   }
 
@@ -72,7 +83,7 @@ static <K, V> Map<K, V> preservesInsertionOrderOnPutsMap() {
    * Returns the platform preferred set implementation that preserves insertion order when used only
    * for insertions.
    */
-  static <E> Set<E> preservesInsertionOrderOnAddsSet() {
+  static <E extends @Nullable Object> Set<E> preservesInsertionOrderOnAddsSet() {
     return Sets.newLinkedHashSet();
   }
 
@@ -82,7 +93,13 @@ static <E> Set<E> preservesInsertionOrderOnAddsSet() {
    * @param reference any array of the desired type
    * @param length the length of the new array
    */
-  static <T> T[] newArray(T[] reference, int length) {
+  /*
+   * The new array contains nulls, even if the old array did not. If we wanted to be accurate, we
+   * would declare a return type of `@Nullable T[]`. However, we've decided not to think too hard
+   * about arrays for now, as they're a mess. (We previously discussed this in the review of
+   * ObjectArrays, which is the main caller of this method.)
+   */
+  static <T extends @Nullable Object> T[] newArray(T[] reference, int length) {
     Class<?> type = reference.getClass().getComponentType();
 
     // the cast is safe because
@@ -93,7 +110,16 @@ static <T> T[] newArray(T[] reference, int length) {
   }
 
   /** Equivalent to Arrays.copyOfRange(source, from, to, arrayOfType.getClass()). */
-  static <T> T[] copy(Object[] source, int from, int to, T[] arrayOfType) {
+  /*
+   * Arrays are a mess from a nullness perspective, and Class instances for object-array types are
+   * even worse. For now, we just suppress and move on with our lives.
+   *
+   * - https://github.com/jspecify/jspecify/issues/65
+   *
+   * - https://github.com/jspecify/jdk/commit/71d826792b8c7ef95d492c50a274deab938f2552
+   */
+  @SuppressWarnings("nullness")
+  static <T extends @Nullable Object> T[] copy(Object[] source, int from, int to, T[] arrayOfType) {
     return Arrays.copyOfRange(source, from, to, (Class<? extends T[]>) arrayOfType.getClass());
   }
 
diff --git a/guava/src/com/google/common/collect/Queues.java b/guava/src/com/google/common/collect/Queues.java
index 8a6932645440..a140102fd6db 100644
--- a/guava/src/com/google/common/collect/Queues.java
+++ b/guava/src/com/google/common/collect/Queues.java
@@ -32,6 +32,7 @@
 import java.util.concurrent.PriorityBlockingQueue;
 import java.util.concurrent.SynchronousQueue;
 import java.util.concurrent.TimeUnit;
+import org.checkerframework.checker.nullness.qual.Nullable;
 
 /**
  * Static utility methods pertaining to {@link Queue} and {@link Deque} instances. Also see this
@@ -41,6 +42,7 @@
  * @since 11.0
  */
 @GwtCompatible(emulated = true)
+@ElementTypesAreNonnullByDefault
 public final class Queues {
   private Queues() {}
 
@@ -188,7 +190,8 @@ public static <E> LinkedBlockingQueue<E> newLinkedBlockingQueue(Iterable<? exten
    * Creates an empty {@code PriorityBlockingQueue} with the ordering given by its elements' natural
    * ordering.
    *
-   * @since 11.0 (requires that {@code E} be {@code Comparable} since 15.0).
+   * @since 11.0 (but the bound of {@code E} was changed from {@code Object} to {@code Comparable}
+   *     in 15.0)
    */
   @GwtIncompatible // PriorityBlockingQueue
   public static <E extends Comparable> PriorityBlockingQueue<E> newPriorityBlockingQueue() {
@@ -201,7 +204,8 @@ public static <E extends Comparable> PriorityBlockingQueue<E> newPriorityBlockin
    * <p><b>Note:</b> If the specified iterable is a {@code SortedSet} or a {@code PriorityQueue},
    * this priority queue will be ordered according to the same ordering.
    *
-   * @since 11.0 (requires that {@code E} be {@code Comparable} since 15.0).
+   * @since 11.0 (but the bound of {@code E} was changed from {@code Object} to {@code Comparable}
+   *     in 15.0)
    */
   @GwtIncompatible // PriorityBlockingQueue
   public static <E extends Comparable> PriorityBlockingQueue<E> newPriorityBlockingQueue(
@@ -220,7 +224,8 @@ public static <E extends Comparable> PriorityBlockingQueue<E> newPriorityBlockin
    * Creates an empty {@code PriorityQueue} with the ordering given by its elements' natural
    * ordering.
    *
-   * @since 11.0 (requires that {@code E} be {@code Comparable} since 15.0).
+   * @since 11.0 (but the bound of {@code E} was changed from {@code Object} to {@code Comparable}
+   *     in 15.0)
    */
   public static <E extends Comparable> PriorityQueue<E> newPriorityQueue() {
     return new PriorityQueue<E>();
@@ -232,7 +237,8 @@ public static <E extends Comparable> PriorityQueue<E> newPriorityQueue() {
    * <p><b>Note:</b> If the specified iterable is a {@code SortedSet} or a {@code PriorityQueue},
    * this priority queue will be ordered according to the same ordering.
    *
-   * @since 11.0 (requires that {@code E} be {@code Comparable} since 15.0).
+   * @since 11.0 (but the bound of {@code E} was changed from {@code Object} to {@code Comparable}
+   *     in 15.0)
    */
   public static <E extends Comparable> PriorityQueue<E> newPriorityQueue(
       Iterable<? extends E> elements) {
@@ -432,7 +438,7 @@ public static <E> int drainUninterruptibly(
    * @return a synchronized view of the specified queue
    * @since 14.0
    */
-  public static <E> Queue<E> synchronizedQueue(Queue<E> queue) {
+  public static <E extends @Nullable Object> Queue<E> synchronizedQueue(Queue<E> queue) {
     return Synchronized.queue(queue, null);
   }
 
@@ -465,7 +471,7 @@ public static <E> Queue<E> synchronizedQueue(Queue<E> queue) {
    * @return a synchronized view of the specified deque
    * @since 15.0
    */
-  public static <E> Deque<E> synchronizedDeque(Deque<E> deque) {
+  public static <E extends @Nullable Object> Deque<E> synchronizedDeque(Deque<E> deque) {
     return Synchronized.deque(deque, null);
   }
 }
diff --git a/guava/src/com/google/common/collect/Range.java b/guava/src/com/google/common/collect/Range.java
index 1c6002eaee9a..2a5d464dc2a8 100644
--- a/guava/src/com/google/common/collect/Range.java
+++ b/guava/src/com/google/common/collect/Range.java
@@ -16,6 +16,7 @@
 
 package com.google.common.collect;
 
+import static com.google.common.base.Preconditions.checkArgument;
 import static com.google.common.base.Preconditions.checkNotNull;
 
 import com.google.common.annotations.GwtCompatible;
@@ -27,7 +28,7 @@
 import java.util.Iterator;
 import java.util.NoSuchElementException;
 import java.util.SortedSet;
-import org.checkerframework.checker.nullness.qual.Nullable;
+import javax.annotation.CheckForNull;
 
 /**
  * A range (or "interval") defines the <i>boundaries</i> around a contiguous span of values of some
@@ -117,6 +118,7 @@
  */
 @GwtCompatible
 @SuppressWarnings("rawtypes")
+@ElementTypesAreNonnullByDefault
 public final class Range<C extends Comparable> extends RangeGwtSerializationDependencies
     implements Predicate<C>, Serializable {
 
@@ -153,7 +155,7 @@ static <C extends Comparable<?>> Ordering<Range<C>> rangeLexOrdering() {
   }
 
   static <C extends Comparable<?>> Range<C> create(Cut<C> lowerBound, Cut<C> upperBound) {
-    return new Range<C>(lowerBound, upperBound);
+    return new Range<>(lowerBound, upperBound);
   }
 
   /**
@@ -329,7 +331,7 @@ public static <C extends Comparable<?>> Range<C> singleton(C value) {
   public static <C extends Comparable<?>> Range<C> encloseAll(Iterable<C> values) {
     checkNotNull(values);
     if (values instanceof SortedSet) {
-      SortedSet<? extends C> set = cast(values);
+      SortedSet<C> set = (SortedSet<C>) values;
       Comparator<?> comparator = set.comparator();
       if (Ordering.natural().equals(comparator) || comparator == null) {
         return closed(set.first(), set.last());
@@ -456,7 +458,7 @@ public boolean containsAll(Iterable<? extends C> values) {
 
     // this optimizes testing equality of two range-backed sets
     if (values instanceof SortedSet) {
-      SortedSet<? extends C> set = cast(values);
+      SortedSet<? extends C> set = (SortedSet<? extends C>) values;
       Comparator<?> comparator = set.comparator();
       if (Ordering.natural().equals(comparator) || comparator == null) {
         return contains(set.first()) && contains(set.last());
@@ -555,6 +557,15 @@ public Range<C> intersection(Range<C> connectedRange) {
     } else {
       Cut<C> newLower = (lowerCmp >= 0) ? lowerBound : connectedRange.lowerBound;
       Cut<C> newUpper = (upperCmp <= 0) ? upperBound : connectedRange.upperBound;
+
+      // create() would catch this, but give a confusing error message
+      checkArgument(
+          newLower.compareTo(newUpper) <= 0,
+          "intersection is undefined for disconnected ranges %s and %s",
+          this,
+          connectedRange);
+
+      // TODO(kevinb): all the precondition checks in the constructor are redundant...
       return create(newLower, newUpper);
     }
   }
@@ -663,7 +674,7 @@ public Range<C> canonical(DiscreteDomain<C> domain) {
    * {@code [3..3)}, {@code (3..3]}, {@code (4..4]} are all unequal.
    */
   @Override
-  public boolean equals(@Nullable Object object) {
+  public boolean equals(@CheckForNull Object object) {
     if (object instanceof Range) {
       Range<?> other = (Range<?>) object;
       return lowerBound.equals(other.lowerBound) && upperBound.equals(other.upperBound);
@@ -694,11 +705,6 @@ private static String toString(Cut<?> lowerBound, Cut<?> upperBound) {
     return sb.toString();
   }
 
-  /** Used to avoid http://bugs.sun.com/view_bug.do?bug_id=6558557 */
-  private static <T> SortedSet<T> cast(Iterable<T> iterable) {
-    return (SortedSet<T>) iterable;
-  }
-
   Object readResolve() {
     if (this.equals(ALL)) {
       return all();
diff --git a/guava/src/com/google/common/collect/RangeMap.java b/guava/src/com/google/common/collect/RangeMap.java
index 0b319bdb61b9..99e7b97d5ee9 100644
--- a/guava/src/com/google/common/collect/RangeMap.java
+++ b/guava/src/com/google/common/collect/RangeMap.java
@@ -24,6 +24,7 @@
 import java.util.Map.Entry;
 import java.util.NoSuchElementException;
 import java.util.function.BiFunction;
+import javax.annotation.CheckForNull;
 import org.checkerframework.checker.nullness.qual.Nullable;
 
 /**
@@ -39,21 +40,27 @@
 @Beta
 @DoNotMock("Use ImmutableRangeMap or TreeRangeMap")
 @GwtIncompatible
+@ElementTypesAreNonnullByDefault
 public interface RangeMap<K extends Comparable, V> {
+  /*
+   * TODO(cpovirk): These docs sometimes say "map" and sometimes say "range map." Pick one, or at
+   * least decide on a policy for when to use which.
+   */
+
   /**
    * Returns the value associated with the specified key, or {@code null} if there is no such value.
    *
    * <p>Specifically, if any range in this range map contains the specified key, the value
    * associated with that range is returned.
    */
-  @Nullable
+  @CheckForNull
   V get(K key);
 
   /**
    * Returns the range containing this key and its associated value, if such a range is present in
    * the range map, or {@code null} otherwise.
    */
-  @Nullable
+  @CheckForNull
   Entry<Range<K>, V> getEntry(K key);
 
   /**
@@ -111,25 +118,27 @@ public interface RangeMap<K extends Comparable, V> {
   void remove(Range<K> range);
 
   /**
-   * Merges a value into the map over a range by applying a remapping function.
+   * Merges a value into a part of the map by applying a remapping function.
    *
-   * <p>If any parts of the range are already present in this range map, those parts are mapped to
-   * new values by applying the remapping function. Any parts of the range not already present in
-   * this range map are mapped to the specified value, unless the value is {@code null}.
+   * <p>If any parts of the range are already present in this map, those parts are mapped to new
+   * values by applying the remapping function. The remapping function accepts the map's existing
+   * value for that part of the range and the given value. It returns the value to be associated
+   * with that part of the map, or it returns {@code null} to clear that part of the map.
    *
-   * <p>Any existing map entry spanning either range boundary may be split at the boundary, even if
-   * the merge does not affect its value.
+   * <p>Any parts of the range not already present in this map are mapped to the specified value,
+   * unless the value is {@code null}.
    *
-   * <p>For example, if {@code rangeMap} had one entry {@code [1, 5] => 3} then {@code
-   * rangeMap.merge(Range.closed(0,2), 3, Math::max)} could yield a range map with the entries
-   * {@code [0, 1) => 3, [1, 2] => 3, (2, 5] => 3}.
+   * <p>Any existing entry spanning either range boundary may be split at the boundary, even if the
+   * merge does not affect its value. For example, if {@code rangeMap} had one entry {@code [1, 5]
+   * => 3} then {@code rangeMap.merge(Range.closed(0,2), 3, Math::max)} could yield a map with the
+   * entries {@code [0, 1) => 3, [1, 2] => 3, (2, 5] => 3}.
    *
    * @since 28.1
    */
   void merge(
       Range<K> range,
-      @Nullable V value,
-      BiFunction<? super V, ? super V, ? extends V> remappingFunction);
+      @CheckForNull V value,
+      BiFunction<? super V, ? super @Nullable V, ? extends @Nullable V> remappingFunction);
 
   /**
    * Returns a view of this range map as an unmodifiable {@code Map<Range<K>, V>}. Modifications to
@@ -168,6 +177,7 @@ void merge(
    * <p>The returned range map will throw an {@link IllegalArgumentException} on an attempt to
    * insert a range not {@linkplain Range#encloses(Range) enclosed} by {@code range}.
    */
+  // TODO(cpovirk): Consider documenting that IAE on the various methods that can throw it.
   RangeMap<K, V> subRangeMap(Range<K> range);
 
   /**
@@ -175,7 +185,7 @@ void merge(
    * #asMapOfRanges()}.
    */
   @Override
-  boolean equals(@Nullable Object o);
+  boolean equals(@CheckForNull Object o);
 
   /** Returns {@code asMapOfRanges().hashCode()}. */
   @Override
diff --git a/guava/src/com/google/common/collect/RangeSet.java b/guava/src/com/google/common/collect/RangeSet.java
index 4805108c1b6a..79fbab159fa5 100644
--- a/guava/src/com/google/common/collect/RangeSet.java
+++ b/guava/src/com/google/common/collect/RangeSet.java
@@ -15,11 +15,11 @@
 package com.google.common.collect;
 
 import com.google.common.annotations.Beta;
-import com.google.errorprone.annotations.DoNotMock;
 import com.google.common.annotations.GwtIncompatible;
+import com.google.errorprone.annotations.DoNotMock;
 import java.util.NoSuchElementException;
 import java.util.Set;
-import org.checkerframework.checker.nullness.qual.Nullable;
+import javax.annotation.CheckForNull;
 
 /**
  * A set comprising zero or more {@linkplain Range#isEmpty nonempty}, {@linkplain
@@ -43,7 +43,7 @@
  * <p>For a {@link Set} whose contents are specified by a {@link Range}, see {@link ContiguousSet}.
  *
  * <p>See the Guava User Guide article on <a href=
- * "https://github.com/google/guava/wiki/NewCollectionTypesExplained#rangeset"> RangeSets</a>.
+ * "https://github.com/google/guava/wiki/NewCollectionTypesExplained#rangeset">RangeSets</a>.
  *
  * @author Kevin Bourrillion
  * @author Louis Wasserman
@@ -52,6 +52,7 @@
 @Beta
 @DoNotMock("Use ImmutableRangeSet or TreeRangeSet")
 @GwtIncompatible
+@ElementTypesAreNonnullByDefault
 public interface RangeSet<C extends Comparable> {
   // TODO(lowasser): consider adding default implementations of some of these methods
 
@@ -64,6 +65,7 @@ public interface RangeSet<C extends Comparable> {
    * Returns the unique range from this range set that {@linkplain Range#contains contains} {@code
    * value}, or {@code null} if this range set does not contain {@code value}.
    */
+  @CheckForNull
   Range<C> rangeContaining(C value);
 
   /**
@@ -262,7 +264,7 @@ default void removeAll(Iterable<Range<C>> ranges) {
    * according to {@link Range#equals(Object)}.
    */
   @Override
-  boolean equals(@Nullable Object obj);
+  boolean equals(@CheckForNull Object obj);
 
   /** Returns {@code asRanges().hashCode()}. */
   @Override
diff --git a/guava/src/com/google/common/collect/RegularContiguousSet.java b/guava/src/com/google/common/collect/RegularContiguousSet.java
index 849758579201..787606eb1f81 100644
--- a/guava/src/com/google/common/collect/RegularContiguousSet.java
+++ b/guava/src/com/google/common/collect/RegularContiguousSet.java
@@ -18,12 +18,13 @@
 import static com.google.common.base.Preconditions.checkElementIndex;
 import static com.google.common.base.Preconditions.checkNotNull;
 import static com.google.common.collect.BoundType.CLOSED;
+import static java.util.Objects.requireNonNull;
 
 import com.google.common.annotations.GwtCompatible;
 import com.google.common.annotations.GwtIncompatible;
 import java.io.Serializable;
 import java.util.Collection;
-import org.checkerframework.checker.nullness.qual.Nullable;
+import javax.annotation.CheckForNull;
 
 /**
  * An implementation of {@link ContiguousSet} that contains one or more elements.
@@ -32,6 +33,7 @@
  */
 @GwtCompatible(emulated = true)
 @SuppressWarnings("unchecked") // allow ungenerified Comparable types
+@ElementTypesAreNonnullByDefault
 final class RegularContiguousSet<C extends Comparable> extends ContiguousSet<C> {
   private final Range<C> range;
 
@@ -56,7 +58,7 @@ ContiguousSet<C> subSetImpl(
       C fromElement, boolean fromInclusive, C toElement, boolean toInclusive) {
     if (fromElement.compareTo(toElement) == 0 && !fromInclusive && !toInclusive) {
       // Range would reject our attempt to create (x, x).
-      return new EmptyContiguousSet<C>(domain);
+      return new EmptyContiguousSet<>(domain);
     }
     return intersectionInCurrentDomain(
         Range.range(
@@ -71,8 +73,9 @@ ContiguousSet<C> tailSetImpl(C fromElement, boolean inclusive) {
 
   @GwtIncompatible // not used by GWT emulation
   @Override
-  int indexOf(Object target) {
-    return contains(target) ? (int) domain.distance(first(), (C) target) : -1;
+  int indexOf(@CheckForNull Object target) {
+    // requireNonNull is safe because of the contains check.
+    return contains(target) ? (int) domain.distance(first(), (C) requireNonNull(target)) : -1;
   }
 
   @Override
@@ -81,6 +84,7 @@ public UnmodifiableIterator<C> iterator() {
       final C last = last();
 
       @Override
+      @CheckForNull
       protected C computeNext(C previous) {
         return equalsOrThrow(previous, last) ? null : domain.next(previous);
       }
@@ -94,13 +98,14 @@ public UnmodifiableIterator<C> descendingIterator() {
       final C first = first();
 
       @Override
+      @CheckForNull
       protected C computeNext(C previous) {
         return equalsOrThrow(previous, first) ? null : domain.previous(previous);
       }
     };
   }
 
-  private static boolean equalsOrThrow(Comparable<?> left, @Nullable Comparable<?> right) {
+  private static boolean equalsOrThrow(Comparable<?> left, @CheckForNull Comparable<?> right) {
     return right != null && Range.compareOrThrow(left, right) == 0;
   }
 
@@ -111,12 +116,14 @@ boolean isPartialView() {
 
   @Override
   public C first() {
-    return range.lowerBound.leastValueAbove(domain);
+    // requireNonNull is safe because we checked the range is not empty in ContiguousSet.create.
+    return requireNonNull(range.lowerBound.leastValueAbove(domain));
   }
 
   @Override
   public C last() {
-    return range.upperBound.greatestValueBelow(domain);
+    // requireNonNull is safe because we checked the range is not empty in ContiguousSet.create.
+    return requireNonNull(range.upperBound.greatestValueBelow(domain));
   }
 
   @Override
@@ -146,7 +153,7 @@ public int size() {
   }
 
   @Override
-  public boolean contains(@Nullable Object object) {
+  public boolean contains(@CheckForNull Object object) {
     if (object == null) {
       return false;
     }
@@ -195,7 +202,7 @@ public Range<C> range(BoundType lowerBoundType, BoundType upperBoundType) {
   }
 
   @Override
-  public boolean equals(@Nullable Object object) {
+  public boolean equals(@CheckForNull Object object) {
     if (object == this) {
       return true;
     } else if (object instanceof RegularContiguousSet) {
@@ -224,14 +231,14 @@ private SerializedForm(Range<C> range, DiscreteDomain<C> domain) {
     }
 
     private Object readResolve() {
-      return new RegularContiguousSet<C>(range, domain);
+      return new RegularContiguousSet<>(range, domain);
     }
   }
 
   @GwtIncompatible // serialization
   @Override
   Object writeReplace() {
-    return new SerializedForm<C>(range, domain);
+    return new SerializedForm<>(range, domain);
   }
 
   private static final long serialVersionUID = 0;
diff --git a/guava/src/com/google/common/collect/RegularImmutableAsList.java b/guava/src/com/google/common/collect/RegularImmutableAsList.java
index df17b6e341b4..7d0eeb863ae9 100644
--- a/guava/src/com/google/common/collect/RegularImmutableAsList.java
+++ b/guava/src/com/google/common/collect/RegularImmutableAsList.java
@@ -19,6 +19,8 @@
 import com.google.common.annotations.GwtCompatible;
 import com.google.common.annotations.GwtIncompatible;
 import java.util.function.Consumer;
+import javax.annotation.CheckForNull;
+import org.checkerframework.checker.nullness.qual.Nullable;
 
 /**
  * An {@link ImmutableAsList} implementation specialized for when the delegate collection is already
@@ -28,6 +30,7 @@
  */
 @GwtCompatible(emulated = true)
 @SuppressWarnings("serial") // uses writeReplace, not default serialization
+@ElementTypesAreNonnullByDefault
 class RegularImmutableAsList<E> extends ImmutableAsList<E> {
   private final ImmutableCollection<E> delegate;
   private final ImmutableList<? extends E> delegateList;
@@ -58,17 +61,19 @@ public UnmodifiableListIterator<E> listIterator(int index) {
 
   @GwtIncompatible // not present in emulated superclass
   @Override
+  @SuppressWarnings("value:argument")
   public void forEach(Consumer<? super E> action) {
     delegateList.forEach(action);
   }
 
   @GwtIncompatible // not present in emulated superclass
   @Override
-  int copyIntoArray(Object[] dst, int offset) {
+  int copyIntoArray(@Nullable Object[] dst, int offset) {
     return delegateList.copyIntoArray(dst, offset);
   }
 
   @Override
+  @CheckForNull
   Object[] internalArray() {
     return delegateList.internalArray();
   }
diff --git a/guava/src/com/google/common/collect/RegularImmutableBiMap.java b/guava/src/com/google/common/collect/RegularImmutableBiMap.java
index 81f19e1c2104..ed7c4fd1e5b4 100644
--- a/guava/src/com/google/common/collect/RegularImmutableBiMap.java
+++ b/guava/src/com/google/common/collect/RegularImmutableBiMap.java
@@ -20,17 +20,20 @@
 import static com.google.common.base.Preconditions.checkPositionIndex;
 import static com.google.common.collect.CollectPreconditions.checkEntryNotNull;
 import static com.google.common.collect.ImmutableMapEntry.createEntryArray;
+import static com.google.common.collect.RegularImmutableMap.MAX_HASH_BUCKET_LENGTH;
 import static com.google.common.collect.RegularImmutableMap.checkNoConflictInKeyBucket;
+import static java.util.Objects.requireNonNull;
 
 import com.google.common.annotations.GwtCompatible;
 import com.google.common.annotations.VisibleForTesting;
 import com.google.common.collect.ImmutableMapEntry.NonTerminalImmutableBiMapEntry;
-import com.google.errorprone.annotations.CanIgnoreReturnValue;
+import com.google.common.collect.RegularImmutableMap.BucketOverflowException;
 import com.google.errorprone.annotations.concurrent.LazyInit;
 import com.google.j2objc.annotations.RetainedWith;
 import java.io.Serializable;
 import java.util.function.BiConsumer;
 import java.util.function.Consumer;
+import javax.annotation.CheckForNull;
 import org.checkerframework.checker.nullness.qual.Nullable;
 import org.checkerframework.framework.qual.AnnotatedFor;
 
@@ -42,6 +45,7 @@
 @AnnotatedFor({"nullness"})
 @GwtCompatible(serializable = true, emulated = true)
 @SuppressWarnings("serial") // uses writeReplace(), not default serialization
+@ElementTypesAreNonnullByDefault
 class RegularImmutableBiMap<K, V> extends ImmutableBiMap<K, V> {
   static final RegularImmutableBiMap<Object, Object> EMPTY =
       new RegularImmutableBiMap<>(
@@ -49,8 +53,8 @@ class RegularImmutableBiMap<K, V> extends ImmutableBiMap<K, V> {
 
   static final double MAX_LOAD_FACTOR = 1.2;
 
-  private final transient ImmutableMapEntry<K, V>[] keyTable;
-  private final transient ImmutableMapEntry<K, V>[] valueTable;
+  @CheckForNull private final transient @Nullable ImmutableMapEntry<K, V>[] keyTable;
+  @CheckForNull private final transient @Nullable ImmutableMapEntry<K, V>[] valueTable;
   @VisibleForTesting final transient Entry<K, V>[] entries;
   private final transient int mask;
   private final transient int hashCode;
@@ -59,23 +63,25 @@ static <K, V> ImmutableBiMap<K, V> fromEntries(Entry<K, V>... entries) {
     return fromEntryArray(entries.length, entries);
   }
 
-  static <K, V> ImmutableBiMap<K, V> fromEntryArray(int n, Entry<K, V>[] entryArray) {
+  static <K, V> ImmutableBiMap<K, V> fromEntryArray(int n, @Nullable Entry<K, V>[] entryArray) {
     checkPositionIndex(n, entryArray.length);
     int tableSize = Hashing.closedTableSize(n, MAX_LOAD_FACTOR);
     int mask = tableSize - 1;
-    ImmutableMapEntry<K, V>[] keyTable = createEntryArray(tableSize);
-    ImmutableMapEntry<K, V>[] valueTable = createEntryArray(tableSize);
-    Entry<K, V>[] entries;
-    if (n == entryArray.length) {
-      entries = entryArray;
-    } else {
-      entries = createEntryArray(n);
-    }
+    @Nullable ImmutableMapEntry<K, V>[] keyTable = createEntryArray(tableSize);
+    @Nullable ImmutableMapEntry<K, V>[] valueTable = createEntryArray(tableSize);
+    /*
+     * The cast is safe: n==entryArray.length means that we have filled the whole array with Entry
+     * instances, in which case it is safe to cast it from an array of nullable entries to an array
+     * of non-null entries.
+     */
+    @SuppressWarnings("nullness")
+    Entry<K, V>[] entries =
+        (n == entryArray.length) ? (Entry<K, V>[]) entryArray : createEntryArray(n);
     int hashCode = 0;
 
     for (int i = 0; i < n; i++) {
-      @SuppressWarnings("unchecked")
-      Entry<K, V> entry = entryArray[i];
+      // requireNonNull is safe because the first `n` elements have been filled in.
+      Entry<K, V> entry = requireNonNull(entryArray[i]);
       K key = entry.getKey();
       V value = entry.getValue();
       checkEntryNotNull(key, value);
@@ -85,11 +91,11 @@ static <K, V> ImmutableBiMap<K, V> fromEntryArray(int n, Entry<K, V>[] entryArra
       int valueBucket = Hashing.smear(valueHash) & mask;
 
       ImmutableMapEntry<K, V> nextInKeyBucket = keyTable[keyBucket];
-      int keyBucketLength = checkNoConflictInKeyBucket(key, entry, nextInKeyBucket);
       ImmutableMapEntry<K, V> nextInValueBucket = valueTable[valueBucket];
-      int valueBucketLength = checkNoConflictInValueBucket(value, entry, nextInValueBucket);
-      if (keyBucketLength > RegularImmutableMap.MAX_HASH_BUCKET_LENGTH
-          || valueBucketLength > RegularImmutableMap.MAX_HASH_BUCKET_LENGTH) {
+      try {
+        checkNoConflictInKeyBucket(key, value, nextInKeyBucket, /* throwIfDuplicateKeys= */ true);
+        checkNoConflictInValueBucket(value, entry, nextInValueBucket);
+      } catch (BucketOverflowException e) {
         return JdkBackedImmutableBiMap.create(n, entryArray);
       }
       ImmutableMapEntry<K, V> newEntry =
@@ -106,8 +112,8 @@ static <K, V> ImmutableBiMap<K, V> fromEntryArray(int n, Entry<K, V>[] entryArra
   }
 
   private RegularImmutableBiMap(
-      ImmutableMapEntry<K, V>[] keyTable,
-      ImmutableMapEntry<K, V>[] valueTable,
+      @CheckForNull @Nullable ImmutableMapEntry<K, V>[] keyTable,
+      @CheckForNull @Nullable ImmutableMapEntry<K, V>[] valueTable,
       Entry<K, V>[] entries,
       int mask,
       int hashCode) {
@@ -121,23 +127,26 @@ private RegularImmutableBiMap(
   // checkNoConflictInKeyBucket is static imported from RegularImmutableMap
 
   /**
-   * @return number of entries in this bucket
    * @throws IllegalArgumentException if another entry in the bucket has the same key
+   * @throws BucketOverflowException if this bucket has too many entries, which may indicate a hash
+   *     flooding attack
    */
-  @CanIgnoreReturnValue
-  private static int checkNoConflictInValueBucket(
-      Object value, Entry<?, ?> entry, @Nullable ImmutableMapEntry<?, ?> valueBucketHead) {
+  private static void checkNoConflictInValueBucket(
+      Object value, Entry<?, ?> entry, @CheckForNull ImmutableMapEntry<?, ?> valueBucketHead)
+      throws BucketOverflowException {
     int bucketSize = 0;
     for (; valueBucketHead != null; valueBucketHead = valueBucketHead.getNextInValueBucket()) {
       checkNoConflict(!value.equals(valueBucketHead.getValue()), "value", entry, valueBucketHead);
-      bucketSize++;
+      if (++bucketSize > MAX_HASH_BUCKET_LENGTH) {
+        throw new BucketOverflowException();
+      }
     }
-    return bucketSize;
   }
 
   @Override
-  public @Nullable V get(@Nullable Object key) {
-    return (keyTable == null) ? null : RegularImmutableMap.get(key, keyTable, mask);
+  @CheckForNull
+  public V get(@CheckForNull Object key) {
+    return RegularImmutableMap.get(key, keyTable, mask);
   }
 
   @Override
@@ -180,7 +189,7 @@ public int size() {
     return entries.length;
   }
 
-  @LazyInit @RetainedWith private transient ImmutableBiMap<V, K> inverse;
+  @LazyInit @RetainedWith @CheckForNull private transient ImmutableBiMap<V, K> inverse;
 
   @Override
   public ImmutableBiMap<V, K> inverse() {
@@ -210,7 +219,8 @@ public void forEach(BiConsumer<? super V, ? super K> action) {
     }
 
     @Override
-    public K get(@Nullable Object value) {
+    @CheckForNull
+    public K get(@CheckForNull Object value) {
       if (value == null || valueTable == null) {
         return null;
       }
diff --git a/guava/src/com/google/common/collect/RegularImmutableList.java b/guava/src/com/google/common/collect/RegularImmutableList.java
index b7f7ea0ded26..9d4a5ba48ae1 100644
--- a/guava/src/com/google/common/collect/RegularImmutableList.java
+++ b/guava/src/com/google/common/collect/RegularImmutableList.java
@@ -33,6 +33,7 @@
 @AnnotatedFor({"nullness"})
 @GwtCompatible(serializable = true, emulated = true)
 @SuppressWarnings("serial") // uses writeReplace(), not default serialization
+@ElementTypesAreNonnullByDefault
 class RegularImmutableList<E> extends ImmutableList<E> {
   static final ImmutableList<Object> EMPTY = new RegularImmutableList<>(new Object[0]);
 
@@ -69,7 +70,7 @@ int internalArrayEnd() {
   }
 
   @Override
-  int copyIntoArray(Object[] dst, int dstOff) {
+  int copyIntoArray(@Nullable Object[] dst, int dstOff) {
     System.arraycopy(array, 0, dst, dstOff, array.length);
     return dstOff + array.length;
   }
diff --git a/guava/src/com/google/common/collect/RegularImmutableMap.java b/guava/src/com/google/common/collect/RegularImmutableMap.java
index 431dcae48d5f..ccbf7c32ed44 100644
--- a/guava/src/com/google/common/collect/RegularImmutableMap.java
+++ b/guava/src/com/google/common/collect/RegularImmutableMap.java
@@ -20,6 +20,7 @@
 import static com.google.common.base.Preconditions.checkPositionIndex;
 import static com.google.common.collect.CollectPreconditions.checkEntryNotNull;
 import static com.google.common.collect.ImmutableMapEntry.createEntryArray;
+import static java.util.Objects.requireNonNull;
 
 import com.google.common.annotations.GwtCompatible;
 import com.google.common.annotations.GwtIncompatible;
@@ -28,7 +29,9 @@
 import com.google.errorprone.annotations.CanIgnoreReturnValue;
 import java.io.Serializable;
 import java.util.Map;
+import java.util.IdentityHashMap;
 import java.util.function.BiConsumer;
+import javax.annotation.CheckForNull;
 import org.checkerframework.checker.nullness.qual.Nullable;
 import org.checkerframework.dataflow.qual.Pure;
 import org.checkerframework.dataflow.qual.SideEffectFree;
@@ -43,6 +46,7 @@
  */
 @AnnotatedFor({"nullness"})
 @GwtCompatible(serializable = true, emulated = true)
+@ElementTypesAreNonnullByDefault
 final class RegularImmutableMap<K, V> extends ImmutableMap<K, V> {
   @SuppressWarnings("unchecked")
   static final ImmutableMap<Object, Object> EMPTY =
@@ -70,12 +74,12 @@ final class RegularImmutableMap<K, V> extends ImmutableMap<K, V> {
   // entries in insertion order
   @VisibleForTesting final transient Entry<K, V>[] entries;
   // array of linked lists of entries
-  private final transient ImmutableMapEntry<K, V>[] table;
+  @CheckForNull private final transient @Nullable ImmutableMapEntry<K, V>[] table;
   // 'and' with an int to get a table index
   private final transient int mask;
 
   static <K, V> ImmutableMap<K, V> fromEntries(Entry<K, V>... entries) {
-    return fromEntryArray(entries.length, entries);
+    return fromEntryArray(entries.length, entries, /* throwIfDuplicateKeys= */ true);
   }
 
   /**
@@ -83,44 +87,121 @@ static <K, V> ImmutableMap<K, V> fromEntries(Entry<K, V>... entries) {
    * the entries in entryArray with its own entry objects (though they will have the same key/value
    * contents), and may take ownership of entryArray.
    */
-  static <K, V> ImmutableMap<K, V> fromEntryArray(int n, Entry<K, V>[] entryArray) {
+  static <K, V> ImmutableMap<K, V> fromEntryArray(
+      int n, @Nullable Entry<K, V>[] entryArray, boolean throwIfDuplicateKeys) {
     checkPositionIndex(n, entryArray.length);
     if (n == 0) {
-      return (RegularImmutableMap<K, V>) EMPTY;
+      @SuppressWarnings("unchecked") // it has no entries so the type variables don't matter
+      ImmutableMap<K, V> empty = (ImmutableMap<K, V>) EMPTY;
+      return empty;
     }
-    Entry<K, V>[] entries;
-    if (n == entryArray.length) {
-      entries = entryArray;
-    } else {
-      entries = createEntryArray(n);
+    try {
+      return fromEntryArrayCheckingBucketOverflow(n, entryArray, throwIfDuplicateKeys);
+    } catch (BucketOverflowException e) {
+      // probable hash flooding attack, fall back to j.u.HM based implementation and use its
+      // implementation of hash flooding protection
+      return JdkBackedImmutableMap.create(n, entryArray, throwIfDuplicateKeys);
     }
+  }
+
+  private static <K, V> ImmutableMap<K, V> fromEntryArrayCheckingBucketOverflow(
+      int n, @Nullable Entry<K, V>[] entryArray, boolean throwIfDuplicateKeys)
+      throws BucketOverflowException {
+    /*
+     * The cast is safe: n==entryArray.length means that we have filled the whole array with Entry
+     * instances, in which case it is safe to cast it from an array of nullable entries to an array
+     * of non-null entries.
+     */
+    @SuppressWarnings("nullness")
+    Entry<K, V>[] entries =
+        (n == entryArray.length) ? (Entry<K, V>[]) entryArray : createEntryArray(n);
     int tableSize = Hashing.closedTableSize(n, MAX_LOAD_FACTOR);
-    ImmutableMapEntry<K, V>[] table = createEntryArray(tableSize);
+    @Nullable ImmutableMapEntry<K, V>[] table = createEntryArray(tableSize);
     int mask = tableSize - 1;
-    for (int entryIndex = 0; entryIndex < n; entryIndex++) {
-      Entry<K, V> entry = entryArray[entryIndex];
+    // If duplicates are allowed, this IdentityHashMap will record the final Entry for each
+    // duplicated key. We will use this final Entry to overwrite earlier slots in the entries array
+    // that have the same key. Then a second pass will remove all but the first of the slots that
+    // have this Entry. The value in the map becomes false when this first entry has been copied, so
+    // we know not to copy the remaining ones.
+    IdentityHashMap<Entry<K, V>, Boolean> duplicates = null;
+    int dupCount = 0;
+    for (int entryIndex = n - 1; entryIndex >= 0; entryIndex--) {
+      // requireNonNull is safe because the first `n` elements have been filled in.
+      Entry<K, V> entry = requireNonNull(entryArray[entryIndex]);
       K key = entry.getKey();
       V value = entry.getValue();
       checkEntryNotNull(key, value);
       int tableIndex = Hashing.smear(key.hashCode()) & mask;
-      @Nullable ImmutableMapEntry<K, V> existing = table[tableIndex];
-      // prepend, not append, so the entries can be immutable
-      ImmutableMapEntry<K, V> newEntry =
-          (existing == null)
-              ? makeImmutable(entry, key, value)
-              : new NonTerminalImmutableMapEntry<K, V>(key, value, existing);
-      table[tableIndex] = newEntry;
-      entries[entryIndex] = newEntry;
-      int bucketSize = checkNoConflictInKeyBucket(key, newEntry, existing);
-      if (bucketSize > MAX_HASH_BUCKET_LENGTH) {
-        // probable hash flooding attack, fall back to j.u.HM based implementation and use its
-        // implementation of hash flooding protection
-        return JdkBackedImmutableMap.create(n, entryArray);
+      ImmutableMapEntry<K, V> keyBucketHead = table[tableIndex];
+      ImmutableMapEntry<K, V> effectiveEntry =
+          checkNoConflictInKeyBucket(key, value, keyBucketHead, throwIfDuplicateKeys);
+      if (effectiveEntry == null) {
+        // prepend, not append, so the entries can be immutable
+        effectiveEntry =
+            (keyBucketHead == null)
+                ? makeImmutable(entry, key, value)
+                : new NonTerminalImmutableMapEntry<K, V>(key, value, keyBucketHead);
+        table[tableIndex] = effectiveEntry;
+      } else {
+        // We already saw this key, and the first value we saw (going backwards) is the one we are
+        // keeping. So we won't touch table[], but we do still want to add the existing entry that
+        // we found to entries[] so that we will see this key in the right place when iterating.
+        if (duplicates == null) {
+          duplicates = new IdentityHashMap<>();
+        }
+        duplicates.put(effectiveEntry, true);
+        dupCount++;
+        // Make sure we are not overwriting the original entries array, in case we later do
+        // buildOrThrow(). We would want an exception to include two values for the duplicate key.
+        if (entries == entryArray) {
+          entries = entries.clone();
+        }
+      }
+      entries[entryIndex] = effectiveEntry;
+    }
+    if (duplicates != null) {
+      // Explicit type parameters needed here to avoid a problem with nullness inference.
+      entries = RegularImmutableMap.<K, V>removeDuplicates(entries, n, n - dupCount, duplicates);
+      int newTableSize = Hashing.closedTableSize(entries.length, MAX_LOAD_FACTOR);
+      if (newTableSize != tableSize) {
+        return fromEntryArrayCheckingBucketOverflow(
+            entries.length, entries, /* throwIfDuplicateKeys= */ true);
       }
     }
     return new RegularImmutableMap<>(entries, table, mask);
   }
 
+  /**
+   * Constructs a new entry array where each duplicated key from the original appears only once, at
+   * its first position but with its final value. The {@code duplicates} map is modified.
+   *
+   * @param entries the original array of entries including duplicates
+   * @param n the number of valid entries in {@code entries}
+   * @param newN the expected number of entries once duplicates are removed
+   * @param duplicates a map of canonical {@link Entry} objects for each duplicate key. This map
+   *     will be updated by the method, setting each value to false as soon as the {@link Entry} has
+   *     been included in the new entry array.
+   * @return an array of {@code newN} entries where no key appears more than once.
+   */
+  static <K, V> Entry<K, V>[] removeDuplicates(
+      Entry<K, V>[] entries, int n, int newN, IdentityHashMap<Entry<K, V>, Boolean> duplicates) {
+    Entry<K, V>[] newEntries = createEntryArray(newN);
+    for (int in = 0, out = 0; in < n; in++) {
+      Entry<K, V> entry = entries[in];
+      Boolean status = duplicates.get(entry);
+      // null=>not dup'd; true=>dup'd, first; false=>dup'd, not first
+      if (status != null) {
+        if (status) {
+          duplicates.put(entry, false);
+        } else {
+          continue; // delete this entry; we already copied an earlier one for the same key
+        }
+      }
+      newEntries[out++] = entry;
+    }
+    return newEntries;
+  }
+
   /** Makes an entry usable internally by a new ImmutableMap without rereading its contents. */
   static <K, V> ImmutableMapEntry<K, V> makeImmutable(Entry<K, V> entry, K key, V value) {
     boolean reusable =
@@ -133,34 +214,60 @@ static <K, V> ImmutableMapEntry<K, V> makeImmutable(Entry<K, V> entry) {
     return makeImmutable(entry, entry.getKey(), entry.getValue());
   }
 
-  private RegularImmutableMap(Entry<K, V>[] entries, ImmutableMapEntry<K, V>[] table, int mask) {
+  private RegularImmutableMap(
+      Entry<K, V>[] entries, @CheckForNull @Nullable ImmutableMapEntry<K, V>[] table, int mask) {
     this.entries = entries;
     this.table = table;
     this.mask = mask;
   }
 
   /**
-   * @return number of entries in this bucket
-   * @throws IllegalArgumentException if another entry in the bucket has the same key
+   * Checks if the given key already appears in the hash chain starting at {@code keyBucketHead}. If
+   * it does not, then null is returned. If it does, then if {@code throwIfDuplicateKeys} is true an
+   * {@code IllegalArgumentException} is thrown, and otherwise the existing {@link Entry} is
+   * returned.
+   *
+   * @throws IllegalArgumentException if another entry in the bucket has the same key and {@code
+   *     throwIfDuplicateKeys} is true
+   * @throws BucketOverflowException if this bucket has too many entries, which may indicate a hash
+   *     flooding attack
    */
   @CanIgnoreReturnValue
-  static int checkNoConflictInKeyBucket(
-      Object key, Entry<?, ?> entry, @Nullable ImmutableMapEntry<?, ?> keyBucketHead) {
+  static <K, V> @Nullable ImmutableMapEntry<K, V> checkNoConflictInKeyBucket(
+      Object key,
+      Object newValue,
+      @CheckForNull ImmutableMapEntry<K, V> keyBucketHead,
+      boolean throwIfDuplicateKeys)
+      throws BucketOverflowException {
     int bucketSize = 0;
     for (; keyBucketHead != null; keyBucketHead = keyBucketHead.getNextInKeyBucket()) {
-      checkNoConflict(!key.equals(keyBucketHead.getKey()), "key", entry, keyBucketHead);
-      bucketSize++;
+      if (keyBucketHead.getKey().equals(key)) {
+        if (throwIfDuplicateKeys) {
+          checkNoConflict(/* safe= */ false, "key", keyBucketHead, key + "=" + newValue);
+        } else {
+          return keyBucketHead;
+        }
+      }
+      if (++bucketSize > MAX_HASH_BUCKET_LENGTH) {
+        throw new BucketOverflowException();
+      }
     }
-    return bucketSize;
+    return null;
   }
 
+  static class BucketOverflowException extends Exception {}
+
   @Override
-  public @Nullable V get(@Nullable Object key) {
+  @CheckForNull
+  public V get(@CheckForNull Object key) {
     return get(key, table, mask);
   }
 
-  static <V> @Nullable V get(
-      @Nullable Object key, ImmutableMapEntry<?, V> @Nullable [] keyTable, int mask) {
+  @CheckForNull
+  static <V> V get(
+      @CheckForNull Object key,
+      @CheckForNull @Nullable ImmutableMapEntry<?, V>[] keyTable,
+      int mask) {
     if (key == null || keyTable == null) {
       return null;
     }
@@ -226,7 +333,7 @@ K get(int index) {
     }
 
     @Override
-    public boolean contains(Object object) {
+    public boolean contains(@CheckForNull Object object) {
       return map.containsKey(object);
     }
 
diff --git a/guava/src/com/google/common/collect/RegularImmutableMultiset.java b/guava/src/com/google/common/collect/RegularImmutableMultiset.java
index 93843da61e06..026919e0d5cf 100644
--- a/guava/src/com/google/common/collect/RegularImmutableMultiset.java
+++ b/guava/src/com/google/common/collect/RegularImmutableMultiset.java
@@ -24,6 +24,7 @@
 import com.google.errorprone.annotations.concurrent.LazyInit;
 import java.util.Arrays;
 import java.util.Collection;
+import javax.annotation.CheckForNull;
 import org.checkerframework.checker.nullness.qual.Nullable;
 
 /**
@@ -34,38 +35,41 @@
  */
 @GwtCompatible(emulated = true, serializable = true)
 @SuppressWarnings("serial") // uses writeReplace(), not default serialization
+@ElementTypesAreNonnullByDefault
 class RegularImmutableMultiset<E> extends ImmutableMultiset<E> {
+  private static final ImmutableEntry<?>[] EMPTY_ARRAY = new ImmutableEntry<?>[0];
   static final ImmutableMultiset<Object> EMPTY = create(ImmutableList.<Entry<Object>>of());
 
   static <E> ImmutableMultiset<E> create(Collection<? extends Entry<? extends E>> entries) {
     int distinct = entries.size();
-    @SuppressWarnings("unchecked")
-    Multisets.ImmutableEntry<E>[] entryArray = new Multisets.ImmutableEntry[distinct];
+    @SuppressWarnings({"unchecked", "rawtypes"})
+    ImmutableEntry<E>[] entryArray = new ImmutableEntry[distinct];
     if (distinct == 0) {
-      return new RegularImmutableMultiset<>(entryArray, null, 0, 0, ImmutableSet.of());
+      return new RegularImmutableMultiset<>(entryArray, EMPTY_ARRAY, 0, 0, ImmutableSet.of());
     }
     int tableSize = Hashing.closedTableSize(distinct, MAX_LOAD_FACTOR);
     int mask = tableSize - 1;
-    @SuppressWarnings("unchecked")
-    Multisets.ImmutableEntry<E>[] hashTable = new Multisets.ImmutableEntry[tableSize];
+    @SuppressWarnings({"unchecked", "rawtypes"})
+    @Nullable
+    ImmutableEntry<E>[] hashTable = new @Nullable ImmutableEntry[tableSize];
 
     int index = 0;
     int hashCode = 0;
     long size = 0;
-    for (Entry<? extends E> entry : entries) {
+    for (Entry<? extends E> entryWithWildcard : entries) {
+      @SuppressWarnings("unchecked") // safe because we only read from it
+      Entry<E> entry = (Entry<E>) entryWithWildcard;
       E element = checkNotNull(entry.getElement());
       int count = entry.getCount();
       int hash = element.hashCode();
       int bucket = Hashing.smear(hash) & mask;
-      Multisets.ImmutableEntry<E> bucketHead = hashTable[bucket];
-      Multisets.ImmutableEntry<E> newEntry;
+      ImmutableEntry<E> bucketHead = hashTable[bucket];
+      ImmutableEntry<E> newEntry;
       if (bucketHead == null) {
         boolean canReuseEntry =
-            entry instanceof Multisets.ImmutableEntry && !(entry instanceof NonTerminalEntry);
+            entry instanceof ImmutableEntry && !(entry instanceof NonTerminalEntry);
         newEntry =
-            canReuseEntry
-                ? (Multisets.ImmutableEntry<E>) entry
-                : new Multisets.ImmutableEntry<E>(element, count);
+            canReuseEntry ? (ImmutableEntry<E>) entry : new ImmutableEntry<E>(element, count);
       } else {
         newEntry = new NonTerminalEntry<E>(element, count, bucketHead);
       }
@@ -81,12 +85,10 @@ static <E> ImmutableMultiset<E> create(Collection<? extends Entry<? extends E>>
             entryArray, hashTable, Ints.saturatedCast(size), hashCode, null);
   }
 
-  private static boolean hashFloodingDetected(Multisets.ImmutableEntry<?>[] hashTable) {
+  private static boolean hashFloodingDetected(@Nullable ImmutableEntry<?>[] hashTable) {
     for (int i = 0; i < hashTable.length; i++) {
       int bucketLength = 0;
-      for (Multisets.ImmutableEntry<?> entry = hashTable[i];
-          entry != null;
-          entry = entry.nextInBucket()) {
+      for (ImmutableEntry<?> entry = hashTable[i]; entry != null; entry = entry.nextInBucket()) {
         bucketLength++;
         if (bucketLength > MAX_HASH_BUCKET_LENGTH) {
           return true;
@@ -115,19 +117,19 @@ private static boolean hashFloodingDetected(Multisets.ImmutableEntry<?>[] hashTa
    */
   @VisibleForTesting static final int MAX_HASH_BUCKET_LENGTH = 9;
 
-  private final transient Multisets.ImmutableEntry<E>[] entries;
-  private final transient Multisets.ImmutableEntry<E> @Nullable [] hashTable;
+  private final transient ImmutableEntry<E>[] entries;
+  private final transient @Nullable ImmutableEntry<?>[] hashTable;
   private final transient int size;
   private final transient int hashCode;
 
-  @LazyInit private transient ImmutableSet<E> elementSet;
+  @LazyInit @CheckForNull private transient ImmutableSet<E> elementSet;
 
   private RegularImmutableMultiset(
       ImmutableEntry<E>[] entries,
-      ImmutableEntry<E>[] hashTable,
+      @Nullable ImmutableEntry<?>[] hashTable,
       int size,
       int hashCode,
-      ImmutableSet<E> elementSet) {
+      @CheckForNull ImmutableSet<E> elementSet) {
     this.entries = entries;
     this.hashTable = hashTable;
     this.size = size;
@@ -135,8 +137,8 @@ private RegularImmutableMultiset(
     this.elementSet = elementSet;
   }
 
-  private static final class NonTerminalEntry<E> extends Multisets.ImmutableEntry<E> {
-    private final Multisets.ImmutableEntry<E> nextInBucket;
+  private static final class NonTerminalEntry<E> extends ImmutableEntry<E> {
+    private final ImmutableEntry<E> nextInBucket;
 
     NonTerminalEntry(E element, int count, ImmutableEntry<E> nextInBucket) {
       super(element, count);
@@ -155,14 +157,14 @@ boolean isPartialView() {
   }
 
   @Override
-  public int count(@Nullable Object element) {
-    Multisets.ImmutableEntry<E>[] hashTable = this.hashTable;
-    if (element == null || hashTable == null) {
+  public int count(@CheckForNull Object element) {
+    @Nullable ImmutableEntry<?>[] hashTable = this.hashTable;
+    if (element == null || hashTable.length == 0) {
       return 0;
     }
     int hash = Hashing.smearedHash(element);
     int mask = hashTable.length - 1;
-    for (Multisets.ImmutableEntry<E> entry = hashTable[hash & mask];
+    for (ImmutableEntry<?> entry = hashTable[hash & mask];
         entry != null;
         entry = entry.nextInBucket()) {
       if (Objects.equal(element, entry.getElement())) {
diff --git a/guava/src/com/google/common/collect/RegularImmutableSet.java b/guava/src/com/google/common/collect/RegularImmutableSet.java
index df53fa2ca250..b0d970f66766 100644
--- a/guava/src/com/google/common/collect/RegularImmutableSet.java
+++ b/guava/src/com/google/common/collect/RegularImmutableSet.java
@@ -20,6 +20,7 @@
 import com.google.common.annotations.VisibleForTesting;
 import java.util.Spliterator;
 import java.util.Spliterators;
+import javax.annotation.CheckForNull;
 import org.checkerframework.checker.nullness.qual.Nullable;
 import org.checkerframework.dataflow.qual.Pure;
 import org.checkerframework.framework.qual.AnnotatedFor;
@@ -32,29 +33,31 @@
 @AnnotatedFor({"nullness"})
 @GwtCompatible(serializable = true, emulated = true)
 @SuppressWarnings("serial") // uses writeReplace(), not default serialization
-final class RegularImmutableSet<E> extends ImmutableSet<E> {
+@ElementTypesAreNonnullByDefault
+final class RegularImmutableSet<E> extends ImmutableSet.CachingAsList<E> {
+  private static final Object[] EMPTY_ARRAY = new Object[0];
   static final RegularImmutableSet<Object> EMPTY =
-      new RegularImmutableSet<>(new Object[0], 0, null, 0);
+      new RegularImmutableSet<>(EMPTY_ARRAY, 0, EMPTY_ARRAY, 0);
 
   private final transient Object[] elements;
-  // the same elements in hashed positions (plus nulls)
-  @VisibleForTesting final transient Object[] table;
+  private final transient int hashCode;
+  // the same values as `elements` in hashed positions (plus nulls)
+  @VisibleForTesting final transient @Nullable Object[] table;
   // 'and' with an int to get a valid table index.
   private final transient int mask;
-  private final transient int hashCode;
 
-  RegularImmutableSet(Object[] elements, int hashCode, Object[] table, int mask) {
+  RegularImmutableSet(Object[] elements, int hashCode, @Nullable Object[] table, int mask) {
     this.elements = elements;
+    this.hashCode = hashCode;
     this.table = table;
     this.mask = mask;
-    this.hashCode = hashCode;
   }
 
   @Pure
   @Override
-  public boolean contains(@Nullable Object target) {
-    Object[] table = this.table;
-    if (target == null || table == null) {
+  public boolean contains(@CheckForNull Object target) {
+    @Nullable Object[] table = this.table;
+    if (target == null || table.length == 0) {
       return false;
     }
     for (int i = Hashing.smearedHash(target); ; i++) {
@@ -99,14 +102,16 @@ int internalArrayEnd() {
   }
 
   @Override
-  int copyIntoArray(Object[] dst, int offset) {
+  int copyIntoArray(@Nullable Object[] dst, int offset) {
     System.arraycopy(elements, 0, dst, offset, elements.length);
     return offset + elements.length;
   }
 
   @Override
   ImmutableList<E> createAsList() {
-    return (table == null) ? ImmutableList.<E>of() : new RegularImmutableAsList<E>(this, elements);
+    return (table.length == 0)
+        ? ImmutableList.<E>of()
+        : new RegularImmutableAsList<E>(this, elements);
   }
 
   @Override
diff --git a/guava/src/com/google/common/collect/RegularImmutableSortedMultiset.java b/guava/src/com/google/common/collect/RegularImmutableSortedMultiset.java
index 3056d56f4f18..4b7ba87427ac 100644
--- a/guava/src/com/google/common/collect/RegularImmutableSortedMultiset.java
+++ b/guava/src/com/google/common/collect/RegularImmutableSortedMultiset.java
@@ -23,7 +23,7 @@
 import com.google.common.primitives.Ints;
 import java.util.Comparator;
 import java.util.function.ObjIntConsumer;
-import org.checkerframework.checker.nullness.qual.Nullable;
+import javax.annotation.CheckForNull;
 
 /**
  * An immutable sorted multiset with one or more distinct elements.
@@ -32,6 +32,7 @@
  */
 @SuppressWarnings("serial") // uses writeReplace, not default serialization
 @GwtIncompatible
+@ElementTypesAreNonnullByDefault
 final class RegularImmutableSortedMultiset<E> extends ImmutableSortedMultiset<E> {
   private static final long[] ZERO_CUMULATIVE_COUNTS = {0};
 
@@ -76,17 +77,19 @@ public void forEachEntry(ObjIntConsumer<? super E> action) {
   }
 
   @Override
+  @CheckForNull
   public Entry<E> firstEntry() {
     return isEmpty() ? null : getEntry(0);
   }
 
   @Override
+  @CheckForNull
   public Entry<E> lastEntry() {
     return isEmpty() ? null : getEntry(length - 1);
   }
 
   @Override
-  public int count(@Nullable Object element) {
+  public int count(@CheckForNull Object element) {
     int index = elementSet.indexOf(element);
     return (index >= 0) ? getCount(index) : 0;
   }
diff --git a/guava/src/com/google/common/collect/RegularImmutableSortedSet.java b/guava/src/com/google/common/collect/RegularImmutableSortedSet.java
index 6c8efbe92bd4..4872f5faddb8 100644
--- a/guava/src/com/google/common/collect/RegularImmutableSortedSet.java
+++ b/guava/src/com/google/common/collect/RegularImmutableSortedSet.java
@@ -28,6 +28,7 @@
 import java.util.Set;
 import java.util.Spliterator;
 import java.util.function.Consumer;
+import javax.annotation.CheckForNull;
 import org.checkerframework.checker.nullness.qual.Nullable;
 import org.checkerframework.dataflow.qual.Pure;
 import org.checkerframework.dataflow.qual.SideEffectFree;
@@ -43,6 +44,7 @@
 @AnnotatedFor({"nullness"})
 @GwtCompatible(serializable = true, emulated = true)
 @SuppressWarnings({"serial", "rawtypes"})
+@ElementTypesAreNonnullByDefault
 final class RegularImmutableSortedSet<E> extends ImmutableSortedSet<E> {
   static final RegularImmutableSortedSet<Comparable> NATURAL_EMPTY_SET =
       new RegularImmutableSortedSet<>(ImmutableList.<Comparable>of(), Ordering.natural());
@@ -55,6 +57,7 @@ final class RegularImmutableSortedSet<E> extends ImmutableSortedSet<E> {
   }
 
   @Override
+  @CheckForNull
   Object[] internalArray() {
     return elements.internalArray();
   }
@@ -98,7 +101,7 @@ public int size() {
 
   @Pure
   @Override
-  public boolean contains(@Nullable Object o) {
+  public boolean contains(@CheckForNull Object o) {
     try {
       return o != null && unsafeBinarySearch(o) >= 0;
     } catch (ClassCastException e) {
@@ -169,13 +172,13 @@ boolean isPartialView() {
   }
 
   @Override
-  int copyIntoArray(Object[] dst, int offset) {
+  int copyIntoArray(@Nullable Object[] dst, int offset) {
     return elements.copyIntoArray(dst, offset);
   }
 
   @Pure
   @Override
-  public boolean equals(@Nullable Object object) {
+  public boolean equals(@CheckForNull Object object) {
     if (object == this) {
       return true;
     }
@@ -230,24 +233,28 @@ public E last() {
   }
 
   @Override
+  @CheckForNull
   public E lower(E element) {
     int index = headIndex(element, false) - 1;
     return (index == -1) ? null : elements.get(index);
   }
 
   @Override
+  @CheckForNull
   public E floor(E element) {
     int index = headIndex(element, true) - 1;
     return (index == -1) ? null : elements.get(index);
   }
 
   @Override
+  @CheckForNull
   public E ceiling(E element) {
     int index = tailIndex(element, true);
     return (index == size()) ? null : elements.get(index);
   }
 
   @Override
+  @CheckForNull
   public E higher(E element) {
     int index = tailIndex(element, false);
     return (index == size()) ? null : elements.get(index);
@@ -307,7 +314,7 @@ RegularImmutableSortedSet<E> getSubSet(int newFromIndex, int newToIndex) {
   }
 
   @Override
-  int indexOf(@Nullable Object target) {
+  int indexOf(@CheckForNull Object target) {
     if (target == null) {
       return -1;
     }
diff --git a/guava/src/com/google/common/collect/RegularImmutableTable.java b/guava/src/com/google/common/collect/RegularImmutableTable.java
index 1511fa2b467e..337f123b698d 100644
--- a/guava/src/com/google/common/collect/RegularImmutableTable.java
+++ b/guava/src/com/google/common/collect/RegularImmutableTable.java
@@ -24,7 +24,7 @@
 import java.util.LinkedHashSet;
 import java.util.List;
 import java.util.Set;
-import org.checkerframework.checker.nullness.qual.Nullable;
+import javax.annotation.CheckForNull;
 
 /**
  * An implementation of {@link ImmutableTable} holding an arbitrary number of cells.
@@ -32,6 +32,7 @@
  * @author Gregory Kick
  */
 @GwtCompatible
+@ElementTypesAreNonnullByDefault
 abstract class RegularImmutableTable<R, C, V> extends ImmutableTable<R, C, V> {
   RegularImmutableTable() {}
 
@@ -55,7 +56,7 @@ Cell<R, C, V> get(int index) {
     }
 
     @Override
-    public boolean contains(@Nullable Object object) {
+    public boolean contains(@CheckForNull Object object) {
       if (object instanceof Cell) {
         Cell<?, ?, ?> cell = (Cell<?, ?, ?>) object;
         Object value = RegularImmutableTable.this.get(cell.getRowKey(), cell.getColumnKey());
@@ -97,8 +98,8 @@ boolean isPartialView() {
 
   static <R, C, V> RegularImmutableTable<R, C, V> forCells(
       List<Cell<R, C, V>> cells,
-      final @Nullable Comparator<? super R> rowComparator,
-      final @Nullable Comparator<? super C> columnComparator) {
+      @CheckForNull Comparator<? super R> rowComparator,
+      @CheckForNull Comparator<? super C> columnComparator) {
     checkNotNull(cells);
     if (rowComparator != null || columnComparator != null) {
       /*
@@ -109,20 +110,17 @@ static <R, C, V> RegularImmutableTable<R, C, V> forCells(
        * column, the rows in the second column, etc.
        */
       Comparator<Cell<R, C, V>> comparator =
-          new Comparator<Cell<R, C, V>>() {
-            @Override
-            public int compare(Cell<R, C, V> cell1, Cell<R, C, V> cell2) {
-              int rowCompare =
-                  (rowComparator == null)
-                      ? 0
-                      : rowComparator.compare(cell1.getRowKey(), cell2.getRowKey());
-              if (rowCompare != 0) {
-                return rowCompare;
-              }
-              return (columnComparator == null)
-                  ? 0
-                  : columnComparator.compare(cell1.getColumnKey(), cell2.getColumnKey());
+          (Cell<R, C, V> cell1, Cell<R, C, V> cell2) -> {
+            int rowCompare =
+                (rowComparator == null)
+                    ? 0
+                    : rowComparator.compare(cell1.getRowKey(), cell2.getRowKey());
+            if (rowCompare != 0) {
+              return rowCompare;
             }
+            return (columnComparator == null)
+                ? 0
+                : columnComparator.compare(cell1.getColumnKey(), cell2.getColumnKey());
           };
       Collections.sort(cells, comparator);
     }
@@ -135,8 +133,8 @@ static <R, C, V> RegularImmutableTable<R, C, V> forCells(Iterable<Cell<R, C, V>>
 
   private static <R, C, V> RegularImmutableTable<R, C, V> forCellsInternal(
       Iterable<Cell<R, C, V>> cells,
-      @Nullable Comparator<? super R> rowComparator,
-      @Nullable Comparator<? super C> columnComparator) {
+      @CheckForNull Comparator<? super R> rowComparator,
+      @CheckForNull Comparator<? super C> columnComparator) {
     Set<R> rowSpaceBuilder = new LinkedHashSet<>();
     Set<C> columnSpaceBuilder = new LinkedHashSet<>();
     ImmutableList<Cell<R, C, V>> cellList = ImmutableList.copyOf(cells);
@@ -174,7 +172,7 @@ static <R, C, V> RegularImmutableTable<R, C, V> forOrderedComponents(
    * We could have declared this method 'static' but the additional compile-time checks achieved by
    * referencing the type variables seem worthwhile.
    */
-  final void checkNoDuplicate(R rowKey, C columnKey, V existingValue, V newValue) {
+  final void checkNoDuplicate(R rowKey, C columnKey, @CheckForNull V existingValue, V newValue) {
     checkArgument(
         existingValue == null,
         "Duplicate key: (row=%s, column=%s), values: [%s, %s].",
diff --git a/guava/src/com/google/common/collect/ReverseNaturalOrdering.java b/guava/src/com/google/common/collect/ReverseNaturalOrdering.java
index 4a63e0075d79..04e3e1709dbd 100644
--- a/guava/src/com/google/common/collect/ReverseNaturalOrdering.java
+++ b/guava/src/com/google/common/collect/ReverseNaturalOrdering.java
@@ -28,64 +28,65 @@
 @AnnotatedFor({"nullness"})
 @GwtCompatible(serializable = true)
 @SuppressWarnings({"unchecked", "rawtypes"}) // TODO(kevinb): the right way to explain this??
-final class ReverseNaturalOrdering extends Ordering<Comparable> implements Serializable {
+@ElementTypesAreNonnullByDefault
+final class ReverseNaturalOrdering extends Ordering<Comparable<?>> implements Serializable {
   static final ReverseNaturalOrdering INSTANCE = new ReverseNaturalOrdering();
 
   @Pure
   @Override
-  public int compare(Comparable left, Comparable right) {
+  public int compare(Comparable<?> left, Comparable<?> right) {
     checkNotNull(left); // right null is caught later
     if (left == right) {
       return 0;
     }
 
-    return right.compareTo(left);
+    return ((Comparable<Object>) right).compareTo(left);
   }
 
   @Override
-  public <S extends Comparable> Ordering<S> reverse() {
+  public <S extends Comparable<?>> Ordering<S> reverse() {
     return Ordering.natural();
   }
 
   // Override the min/max methods to "hoist" delegation outside loops
 
   @Override
-  public <E extends Comparable> E min(E a, E b) {
+  public <E extends Comparable<?>> E min(E a, E b) {
     return NaturalOrdering.INSTANCE.max(a, b);
   }
 
   @Override
-  public <E extends Comparable> E min(E a, E b, E c, E... rest) {
+  public <E extends Comparable<?>> E min(E a, E b, E c, E... rest) {
     return NaturalOrdering.INSTANCE.max(a, b, c, rest);
   }
 
   @Override
-  public <E extends Comparable> E min(Iterator<E> iterator) {
+  public <E extends Comparable<?>> E min(Iterator<E> iterator) {
     return NaturalOrdering.INSTANCE.max(iterator);
   }
 
   @Override
-  public <E extends Comparable> E min(Iterable<E> iterable) {
+  public <E extends Comparable<?>> E min(Iterable<E> iterable) {
     return NaturalOrdering.INSTANCE.max(iterable);
   }
 
   @Override
-  public <E extends Comparable> E max(E a, E b) {
+  public <E extends Comparable<?>> E max(E a, E b) {
     return NaturalOrdering.INSTANCE.min(a, b);
   }
 
   @Override
-  public <E extends Comparable> E max(E a, E b, E c, E... rest) {
+  public <E extends Comparable<?>> E max(E a, E b, E c, E... rest) {
     return NaturalOrdering.INSTANCE.min(a, b, c, rest);
   }
 
   @Override
-  public <E extends Comparable> E max(Iterator<E> iterator) {
+  public <E extends Comparable<?>> E max(Iterator<E> iterator) {
     return NaturalOrdering.INSTANCE.min(iterator);
   }
 
   @Override
-  public <E extends Comparable> E max(Iterable<E> iterable) {
+  public <E extends Comparable<?>> E max(Iterable<E> iterable) {
     return NaturalOrdering.INSTANCE.min(iterable);
   }
 
diff --git a/guava/src/com/google/common/collect/ReverseOrdering.java b/guava/src/com/google/common/collect/ReverseOrdering.java
index e1b3aa2e88d2..0f1ab8456783 100644
--- a/guava/src/com/google/common/collect/ReverseOrdering.java
+++ b/guava/src/com/google/common/collect/ReverseOrdering.java
@@ -21,6 +21,7 @@
 import com.google.common.annotations.GwtCompatible;
 import java.io.Serializable;
 import java.util.Iterator;
+import javax.annotation.CheckForNull;
 import org.checkerframework.checker.nullness.qual.Nullable;
 import org.checkerframework.dataflow.qual.Pure;
 import org.checkerframework.framework.qual.AnnotatedFor;
@@ -28,7 +29,9 @@
 /** An ordering that uses the reverse of a given order. */
 @AnnotatedFor({"nullness"})
 @GwtCompatible(serializable = true)
-final class ReverseOrdering<T> extends Ordering<T> implements Serializable {
+@ElementTypesAreNonnullByDefault
+final class ReverseOrdering<T extends @Nullable Object> extends Ordering<T>
+    implements Serializable {
   final Ordering<? super T> forwardOrder;
 
   ReverseOrdering(Ordering<? super T> forwardOrder) {
@@ -37,7 +40,7 @@ final class ReverseOrdering<T> extends Ordering<T> implements Serializable {
 
   @Pure
   @Override
-  public int compare(T a, T b) {
+  public int compare(@ParametricNullness T a, @ParametricNullness T b) {
     return forwardOrder.compare(b, a);
   }
 
@@ -50,12 +53,13 @@ public <S extends T> Ordering<S> reverse() {
   // Override the min/max methods to "hoist" delegation outside loops
 
   @Override
-  public <E extends T> E min(E a, E b) {
+  public <E extends T> E min(@ParametricNullness E a, @ParametricNullness E b) {
     return forwardOrder.max(a, b);
   }
 
   @Override
-  public <E extends T> E min(E a, E b, E c, E... rest) {
+  public <E extends T> E min(
+      @ParametricNullness E a, @ParametricNullness E b, @ParametricNullness E c, E... rest) {
     return forwardOrder.max(a, b, c, rest);
   }
 
@@ -70,12 +74,13 @@ public <E extends T> E min(Iterable<E> iterable) {
   }
 
   @Override
-  public <E extends T> E max(E a, E b) {
+  public <E extends T> E max(@ParametricNullness E a, @ParametricNullness E b) {
     return forwardOrder.min(a, b);
   }
 
   @Override
-  public <E extends T> E max(E a, E b, E c, E... rest) {
+  public <E extends T> E max(
+      @ParametricNullness E a, @ParametricNullness E b, @ParametricNullness E c, E... rest) {
     return forwardOrder.min(a, b, c, rest);
   }
 
@@ -97,7 +102,7 @@ public int hashCode() {
 
   @Pure
   @Override
-  public boolean equals(@Nullable Object object) {
+  public boolean equals(@CheckForNull Object object) {
     if (object == this) {
       return true;
     }
diff --git a/guava/src/com/google/common/collect/RowSortedTable.java b/guava/src/com/google/common/collect/RowSortedTable.java
index 9cdae791946d..2c2d773f78db 100644
--- a/guava/src/com/google/common/collect/RowSortedTable.java
+++ b/guava/src/com/google/common/collect/RowSortedTable.java
@@ -21,6 +21,7 @@
 import java.util.Set;
 import java.util.SortedMap;
 import java.util.SortedSet;
+import org.checkerframework.checker.nullness.qual.Nullable;
 
 /**
  * Interface that extends {@code Table} and whose rows are sorted.
@@ -33,7 +34,10 @@
  * @since 8.0
  */
 @GwtCompatible
-public interface RowSortedTable<R, C, V> extends Table<R, C, V> {
+@ElementTypesAreNonnullByDefault
+public interface RowSortedTable<
+        R extends @Nullable Object, C extends @Nullable Object, V extends @Nullable Object>
+    extends Table<R, C, V> {
   /**
    * {@inheritDoc}
    *
diff --git a/guava/src/com/google/common/collect/Serialization.java b/guava/src/com/google/common/collect/Serialization.java
index 34ba1c57f13e..ce584b1d12f0 100644
--- a/guava/src/com/google/common/collect/Serialization.java
+++ b/guava/src/com/google/common/collect/Serialization.java
@@ -23,6 +23,7 @@
 import java.lang.reflect.Field;
 import java.util.Collection;
 import java.util.Map;
+import org.checkerframework.checker.nullness.qual.Nullable;
 import org.checkerframework.framework.qual.AnnotatedFor;
 
 /**
@@ -35,6 +36,7 @@
  */
 @AnnotatedFor({"nullness"})
 @GwtIncompatible
+@ElementTypesAreNonnullByDefault
 final class Serialization {
   private Serialization() {}
 
@@ -56,7 +58,8 @@ static int readCount(ObjectInputStream stream) throws IOException {
    * <p>The serialized output consists of the number of entries, first key, first value, second key,
    * second value, and so on.
    */
-  static <K, V> void writeMap(Map<K, V> map, ObjectOutputStream stream) throws IOException {
+  static <K extends @Nullable Object, V extends @Nullable Object> void writeMap(
+      Map<K, V> map, ObjectOutputStream stream) throws IOException {
     stream.writeInt(map.size());
     for (Map.Entry<K, V> entry : map.entrySet()) {
       stream.writeObject(entry.getKey());
@@ -68,8 +71,8 @@ static <K, V> void writeMap(Map<K, V> map, ObjectOutputStream stream) throws IOE
    * Populates a map by reading an input stream, as part of deserialization. See {@link #writeMap}
    * for the data format.
    */
-  static <K, V> void populateMap(Map<K, V> map, ObjectInputStream stream)
-      throws IOException, ClassNotFoundException {
+  static <K extends @Nullable Object, V extends @Nullable Object> void populateMap(
+      Map<K, V> map, ObjectInputStream stream) throws IOException, ClassNotFoundException {
     int size = stream.readInt();
     populateMap(map, stream, size);
   }
@@ -78,7 +81,8 @@ static <K, V> void populateMap(Map<K, V> map, ObjectInputStream stream)
    * Populates a map by reading an input stream, as part of deserialization. See {@link #writeMap}
    * for the data format. The size is determined by a prior call to {@link #readCount}.
    */
-  static <K, V> void populateMap(Map<K, V> map, ObjectInputStream stream, int size)
+  static <K extends @Nullable Object, V extends @Nullable Object> void populateMap(
+      Map<K, V> map, ObjectInputStream stream, int size)
       throws IOException, ClassNotFoundException {
     for (int i = 0; i < size; i++) {
       @SuppressWarnings("unchecked") // reading data stored by writeMap
@@ -96,8 +100,8 @@ static <K, V> void populateMap(Map<K, V> map, ObjectInputStream stream, int size
    * <p>The serialized output consists of the number of distinct elements, the first element, its
    * count, the second element, its count, and so on.
    */
-  static <E> void writeMultiset(Multiset<E> multiset, ObjectOutputStream stream)
-      throws IOException {
+  static <E extends @Nullable Object> void writeMultiset(
+      Multiset<E> multiset, ObjectOutputStream stream) throws IOException {
     int entryCount = multiset.entrySet().size();
     stream.writeInt(entryCount);
     for (Multiset.Entry<E> entry : multiset.entrySet()) {
@@ -110,8 +114,8 @@ static <E> void writeMultiset(Multiset<E> multiset, ObjectOutputStream stream)
    * Populates a multiset by reading an input stream, as part of deserialization. See {@link
    * #writeMultiset} for the data format.
    */
-  static <E> void populateMultiset(Multiset<E> multiset, ObjectInputStream stream)
-      throws IOException, ClassNotFoundException {
+  static <E extends @Nullable Object> void populateMultiset(
+      Multiset<E> multiset, ObjectInputStream stream) throws IOException, ClassNotFoundException {
     int distinctElements = stream.readInt();
     populateMultiset(multiset, stream, distinctElements);
   }
@@ -121,7 +125,7 @@ static <E> void populateMultiset(Multiset<E> multiset, ObjectInputStream stream)
    * #writeMultiset} for the data format. The number of distinct elements is determined by a prior
    * call to {@link #readCount}.
    */
-  static <E> void populateMultiset(
+  static <E extends @Nullable Object> void populateMultiset(
       Multiset<E> multiset, ObjectInputStream stream, int distinctElements)
       throws IOException, ClassNotFoundException {
     for (int i = 0; i < distinctElements; i++) {
@@ -140,8 +144,8 @@ static <E> void populateMultiset(
    * <p>The serialized output consists of the number of distinct keys, and then for each distinct
    * key: the key, the number of values for that key, and the key's values.
    */
-  static <K, V> void writeMultimap(Multimap<K, V> multimap, ObjectOutputStream stream)
-      throws IOException {
+  static <K extends @Nullable Object, V extends @Nullable Object> void writeMultimap(
+      Multimap<K, V> multimap, ObjectOutputStream stream) throws IOException {
     stream.writeInt(multimap.asMap().size());
     for (Map.Entry<K, Collection<V>> entry : multimap.asMap().entrySet()) {
       stream.writeObject(entry.getKey());
@@ -156,7 +160,8 @@ static <K, V> void writeMultimap(Multimap<K, V> multimap, ObjectOutputStream str
    * Populates a multimap by reading an input stream, as part of deserialization. See {@link
    * #writeMultimap} for the data format.
    */
-  static <K, V> void populateMultimap(Multimap<K, V> multimap, ObjectInputStream stream)
+  static <K extends @Nullable Object, V extends @Nullable Object> void populateMultimap(
+      Multimap<K, V> multimap, ObjectInputStream stream)
       throws IOException, ClassNotFoundException {
     int distinctKeys = stream.readInt();
     populateMultimap(multimap, stream, distinctKeys);
@@ -167,7 +172,7 @@ static <K, V> void populateMultimap(Multimap<K, V> multimap, ObjectInputStream s
    * #writeMultimap} for the data format. The number of distinct keys is determined by a prior call
    * to {@link #readCount}.
    */
-  static <K, V> void populateMultimap(
+  static <K extends @Nullable Object, V extends @Nullable Object> void populateMultimap(
       Multimap<K, V> multimap, ObjectInputStream stream, int distinctKeys)
       throws IOException, ClassNotFoundException {
     for (int i = 0; i < distinctKeys; i++) {
@@ -184,10 +189,10 @@ static <K, V> void populateMultimap(
   }
 
   // Secret sauce for setting final fields; don't make it public.
-  static <T> FieldSetter<T> getFieldSetter(final Class<T> clazz, String fieldName) {
+  static <T> FieldSetter<T> getFieldSetter(Class<T> clazz, String fieldName) {
     try {
       Field field = clazz.getDeclaredField(fieldName);
-      return new FieldSetter<T>(field);
+      return new FieldSetter<>(field);
     } catch (NoSuchFieldException e) {
       throw new AssertionError(e); // programmer error
     }
diff --git a/guava/src/com/google/common/collect/SetMultimap.java b/guava/src/com/google/common/collect/SetMultimap.java
index f3893a450ac0..291b5e207a03 100644
--- a/guava/src/com/google/common/collect/SetMultimap.java
+++ b/guava/src/com/google/common/collect/SetMultimap.java
@@ -22,6 +22,7 @@
 import java.util.Map;
 import java.util.Map.Entry;
 import java.util.Set;
+import javax.annotation.CheckForNull;
 import org.checkerframework.checker.nullness.qual.Nullable;
 import org.checkerframework.dataflow.qual.Pure;
 import org.checkerframework.framework.qual.AnnotatedFor;
@@ -43,16 +44,20 @@
  * {@code equals} comparisons. Use caution if mutable objects are used as keys or values in a {@code
  * SetMultimap}.
  *
+ * <p><b>Warning:</b> Do not modify either a key <i>or a value</i> of a {@code SetMultimap} in a way
+ * that affects its {@link Object#equals} behavior. Undefined behavior and bugs will result.
+ *
  * <p>See the Guava User Guide article on <a href=
- * "https://github.com/google/guava/wiki/NewCollectionTypesExplained#multimap"> {@code
- * Multimap}</a>.
+ * "https://github.com/google/guava/wiki/NewCollectionTypesExplained#multimap">{@code Multimap}</a>.
  *
  * @author Jared Levy
  * @since 2.0
  */
 @GwtCompatible
 @AnnotatedFor({"nullness"})
-public interface SetMultimap<K, V> extends Multimap<K, V> {
+@ElementTypesAreNonnullByDefault
+public interface SetMultimap<K extends @Nullable Object, V extends @Nullable Object>
+    extends Multimap<K, V> {
   /**
    * {@inheritDoc}
    *
@@ -61,7 +66,7 @@ public interface SetMultimap<K, V> extends Multimap<K, V> {
    * interface.
    */
   @Override
-  Set<V> get(@Nullable K key);
+  Set<V> get(@ParametricNullness K key);
 
   /**
    * {@inheritDoc}
@@ -72,7 +77,7 @@ public interface SetMultimap<K, V> extends Multimap<K, V> {
    */
   @CanIgnoreReturnValue
   @Override
-  Set<V> removeAll(@Nullable Object key);
+  Set<V> removeAll(@CheckForNull Object key);
 
   /**
    * {@inheritDoc}
@@ -85,7 +90,7 @@ public interface SetMultimap<K, V> extends Multimap<K, V> {
    */
   @CanIgnoreReturnValue
   @Override
-  Set<V> replaceValues(K key, Iterable<? extends V> values);
+  Set<V> replaceValues(@ParametricNullness K key, Iterable<? extends V> values);
 
   /**
    * {@inheritDoc}
@@ -118,5 +123,5 @@ public interface SetMultimap<K, V> extends Multimap<K, V> {
    */
   @Pure
   @Override
-  boolean equals(@Nullable Object obj);
+  boolean equals(@CheckForNull Object obj);
 }
diff --git a/guava/src/com/google/common/collect/Sets.java b/guava/src/com/google/common/collect/Sets.java
index b77bcfa80ae7..9ea921ca1705 100644
--- a/guava/src/com/google/common/collect/Sets.java
+++ b/guava/src/com/google/common/collect/Sets.java
@@ -28,6 +28,7 @@
 import com.google.common.collect.Collections2.FilteredCollection;
 import com.google.common.math.IntMath;
 import com.google.errorprone.annotations.CanIgnoreReturnValue;
+import com.google.errorprone.annotations.DoNotCall;
 import java.io.Serializable;
 import java.util.AbstractSet;
 import java.util.Arrays;
@@ -51,6 +52,7 @@
 import java.util.function.Consumer;
 import java.util.stream.Collector;
 import java.util.stream.Stream;
+import javax.annotation.CheckForNull;
 import org.checkerframework.checker.nullness.qual.Nullable;
 import org.checkerframework.dataflow.qual.Pure;
 import org.checkerframework.framework.qual.AnnotatedFor;
@@ -60,7 +62,7 @@
  * {@link Lists}, {@link Maps} and {@link Queues}.
  *
  * <p>See the Guava User Guide article on <a href=
- * "https://github.com/google/guava/wiki/CollectionUtilitiesExplained#sets"> {@code Sets}</a>.
+ * "https://github.com/google/guava/wiki/CollectionUtilitiesExplained#sets">{@code Sets}</a>.
  *
  * @author Kevin Bourrillion
  * @author Jared Levy
@@ -69,6 +71,7 @@
  */
 @AnnotatedFor({"nullness"})
 @GwtCompatible(emulated = true)
+@ElementTypesAreNonnullByDefault
 public final class Sets {
   private Sets() {}
 
@@ -76,7 +79,7 @@ private Sets() {}
    * {@link AbstractSet} substitute without the potentially-quadratic {@code removeAll}
    * implementation.
    */
-  abstract static class ImprovedAbstractSet<E> extends AbstractSet<E> {
+  abstract static class ImprovedAbstractSet<E extends @Nullable Object> extends AbstractSet<E> {
     @Override
     public boolean removeAll(Collection<?> c) {
       return removeAllImpl(this, c);
@@ -173,11 +176,11 @@ public static <E extends Enum<E>> EnumSet<E> newEnumSet(
    * using a {@code LinkedHashSet} instead, at the cost of increased memory footprint, to get
    * deterministic iteration behavior.
    *
-   * <p><b>Note for Java 7 and later:</b> this method is now unnecessary and should be treated as
-   * deprecated. Instead, use the {@code HashSet} constructor directly, taking advantage of the new
-   * <a href="http://goo.gl/iz2Wi">"diamond" syntax</a>.
+   * <p><b>Note:</b> this method is now unnecessary and should be treated as deprecated. Instead,
+   * use the {@code HashSet} constructor directly, taking advantage of <a
+   * href="http://goo.gl/iz2Wi">"diamond" syntax</a>.
    */
-  public static <E> HashSet<E> newHashSet() {
+  public static <E extends @Nullable Object> HashSet<E> newHashSet() {
     return new HashSet<E>();
   }
 
@@ -194,7 +197,7 @@ public static <E> HashSet<E> newHashSet() {
    * asList}{@code (...))}, or for creating an empty set then calling {@link Collections#addAll}.
    * This method is not actually very useful and will likely be deprecated in the future.
    */
-  public static <E> HashSet<E> newHashSet(E... elements) {
+  public static <E extends @Nullable Object> HashSet<E> newHashSet(E... elements) {
     HashSet<E> set = newHashSetWithExpectedSize(elements.length);
     Collections.addAll(set, elements);
     return set;
@@ -212,13 +215,13 @@ public static <E> HashSet<E> newHashSet(E... elements) {
    * <p><b>Note:</b> if {@code E} is an {@link Enum} type, use {@link #newEnumSet(Iterable, Class)}
    * instead.
    *
-   * <p><b>Note for Java 7 and later:</b> if {@code elements} is a {@link Collection}, you don't
-   * need this method. Instead, use the {@code HashSet} constructor directly, taking advantage of
-   * the new <a href="http://goo.gl/iz2Wi">"diamond" syntax</a>.
+   * <p><b>Note:</b> if {@code elements} is a {@link Collection}, you don't need this method.
+   * Instead, use the {@code HashSet} constructor directly, taking advantage of <a
+   * href="http://goo.gl/iz2Wi">"diamond" syntax</a>.
    *
    * <p>Overall, this method is not very useful and will likely be deprecated in the future.
    */
-  public static <E> HashSet<E> newHashSet(Iterable<? extends E> elements) {
+  public static <E extends @Nullable Object> HashSet<E> newHashSet(Iterable<? extends E> elements) {
     return (elements instanceof Collection)
         ? new HashSet<E>((Collection<? extends E>) elements)
         : newHashSet(elements.iterator());
@@ -236,7 +239,7 @@ public static <E> HashSet<E> newHashSet(Iterable<? extends E> elements) {
    *
    * <p>Overall, this method is not very useful and will likely be deprecated in the future.
    */
-  public static <E> HashSet<E> newHashSet(Iterator<? extends E> elements) {
+  public static <E extends @Nullable Object> HashSet<E> newHashSet(Iterator<? extends E> elements) {
     HashSet<E> set = newHashSet();
     Iterators.addAll(set, elements);
     return set;
@@ -254,7 +257,8 @@ public static <E> HashSet<E> newHashSet(Iterator<? extends E> elements) {
    *     without resizing
    * @throws IllegalArgumentException if {@code expectedSize} is negative
    */
-  public static <E> HashSet<E> newHashSetWithExpectedSize(int expectedSize) {
+  public static <E extends @Nullable Object> HashSet<E> newHashSetWithExpectedSize(
+      int expectedSize) {
     return new HashSet<E>(Maps.capacity(expectedSize));
   }
 
@@ -269,7 +273,7 @@ public static <E> HashSet<E> newHashSetWithExpectedSize(int expectedSize) {
    * @since 15.0
    */
   public static <E> Set<E> newConcurrentHashSet() {
-    return Collections.newSetFromMap(new ConcurrentHashMap<E, Boolean>());
+    return Platform.newConcurrentHashSet();
   }
 
   /**
@@ -298,13 +302,13 @@ public static <E> Set<E> newConcurrentHashSet(Iterable<? extends E> elements) {
    *
    * <p><b>Note:</b> if mutability is not required, use {@link ImmutableSet#of()} instead.
    *
-   * <p><b>Note for Java 7 and later:</b> this method is now unnecessary and should be treated as
-   * deprecated. Instead, use the {@code LinkedHashSet} constructor directly, taking advantage of
-   * the new <a href="http://goo.gl/iz2Wi">"diamond" syntax</a>.
+   * <p><b>Note:</b> this method is now unnecessary and should be treated as deprecated. Instead,
+   * use the {@code LinkedHashSet} constructor directly, taking advantage of <a
+   * href="http://goo.gl/iz2Wi">"diamond" syntax</a>.
    *
    * @return a new, empty {@code LinkedHashSet}
    */
-  public static <E> LinkedHashSet<E> newLinkedHashSet() {
+  public static <E extends @Nullable Object> LinkedHashSet<E> newLinkedHashSet() {
     return new LinkedHashSet<E>();
   }
 
@@ -314,16 +318,17 @@ public static <E> LinkedHashSet<E> newLinkedHashSet() {
    * <p><b>Note:</b> if mutability is not required and the elements are non-null, use {@link
    * ImmutableSet#copyOf(Iterable)} instead.
    *
-   * <p><b>Note for Java 7 and later:</b> if {@code elements} is a {@link Collection}, you don't
-   * need this method. Instead, use the {@code LinkedHashSet} constructor directly, taking advantage
-   * of the new <a href="http://goo.gl/iz2Wi">"diamond" syntax</a>.
+   * <p><b>Note:</b> if {@code elements} is a {@link Collection}, you don't need this method.
+   * Instead, use the {@code LinkedHashSet} constructor directly, taking advantage of <a
+   * href="http://goo.gl/iz2Wi">"diamond" syntax</a>.
    *
    * <p>Overall, this method is not very useful and will likely be deprecated in the future.
    *
    * @param elements the elements that the set should contain, in order
    * @return a new {@code LinkedHashSet} containing those elements (minus duplicates)
    */
-  public static <E> LinkedHashSet<E> newLinkedHashSet(Iterable<? extends E> elements) {
+  public static <E extends @Nullable Object> LinkedHashSet<E> newLinkedHashSet(
+      Iterable<? extends E> elements) {
     if (elements instanceof Collection) {
       return new LinkedHashSet<E>((Collection<? extends E>) elements);
     }
@@ -344,7 +349,8 @@ public static <E> LinkedHashSet<E> newLinkedHashSet(Iterable<? extends E> elemen
    * @throws IllegalArgumentException if {@code expectedSize} is negative
    * @since 11.0
    */
-  public static <E> LinkedHashSet<E> newLinkedHashSetWithExpectedSize(int expectedSize) {
+  public static <E extends @Nullable Object> LinkedHashSet<E> newLinkedHashSetWithExpectedSize(
+      int expectedSize) {
     return new LinkedHashSet<E>(Maps.capacity(expectedSize));
   }
 
@@ -356,9 +362,9 @@ public static <E> LinkedHashSet<E> newLinkedHashSetWithExpectedSize(int expected
    *
    * <p><b>Note:</b> if mutability is not required, use {@link ImmutableSortedSet#of()} instead.
    *
-   * <p><b>Note for Java 7 and later:</b> this method is now unnecessary and should be treated as
-   * deprecated. Instead, use the {@code TreeSet} constructor directly, taking advantage of the new
-   * <a href="http://goo.gl/iz2Wi">"diamond" syntax</a>.
+   * <p><b>Note:</b> this method is now unnecessary and should be treated as deprecated. Instead,
+   * use the {@code TreeSet} constructor directly, taking advantage of <a
+   * href="http://goo.gl/iz2Wi">"diamond" syntax</a>.
    *
    * @return a new, empty {@code TreeSet}
    */
@@ -377,9 +383,9 @@ public static <E> LinkedHashSet<E> newLinkedHashSetWithExpectedSize(int expected
    * method has different behavior than {@link TreeSet#TreeSet(SortedSet)}, which returns a {@code
    * TreeSet} with that comparator.
    *
-   * <p><b>Note for Java 7 and later:</b> this method is now unnecessary and should be treated as
-   * deprecated. Instead, use the {@code TreeSet} constructor directly, taking advantage of the new
-   * <a href="http://goo.gl/iz2Wi">"diamond" syntax</a>.
+   * <p><b>Note:</b> this method is now unnecessary and should be treated as deprecated. Instead,
+   * use the {@code TreeSet} constructor directly, taking advantage of <a
+   * href="http://goo.gl/iz2Wi">"diamond" syntax</a>.
    *
    * <p>This method is just a small convenience for creating an empty set and then calling {@link
    * Iterables#addAll}. This method is not very useful and will likely be deprecated in the future.
@@ -399,17 +405,18 @@ public static <E> LinkedHashSet<E> newLinkedHashSetWithExpectedSize(int expected
    * <p><b>Note:</b> if mutability is not required, use {@code
    * ImmutableSortedSet.orderedBy(comparator).build()} instead.
    *
-   * <p><b>Note for Java 7 and later:</b> this method is now unnecessary and should be treated as
-   * deprecated. Instead, use the {@code TreeSet} constructor directly, taking advantage of the new
-   * <a href="http://goo.gl/iz2Wi">"diamond" syntax</a>. One caveat to this is that the {@code
-   * TreeSet} constructor uses a null {@code Comparator} to mean "natural ordering," whereas this
-   * factory rejects null. Clean your code accordingly.
+   * <p><b>Note:</b> this method is now unnecessary and should be treated as deprecated. Instead,
+   * use the {@code TreeSet} constructor directly, taking advantage of <a
+   * href="http://goo.gl/iz2Wi">"diamond" syntax</a>. One caveat to this is that the {@code TreeSet}
+   * constructor uses a null {@code Comparator} to mean "natural ordering," whereas this factory
+   * rejects null. Clean your code accordingly.
    *
    * @param comparator the comparator to use to sort the set
    * @return a new, empty {@code TreeSet}
    * @throws NullPointerException if {@code comparator} is null
    */
-  public static <E> TreeSet<E> newTreeSet(Comparator<? super E> comparator) {
+  public static <E extends @Nullable Object> TreeSet<E> newTreeSet(
+      Comparator<? super E> comparator) {
     return new TreeSet<E>(checkNotNull(comparator));
   }
 
@@ -422,7 +429,7 @@ public static <E> TreeSet<E> newTreeSet(Comparator<? super E> comparator) {
    *
    * @since 8.0
    */
-  public static <E> Set<E> newIdentityHashSet() {
+  public static <E extends @Nullable Object> Set<E> newIdentityHashSet() {
     return Collections.newSetFromMap(Maps.<E, Boolean>newIdentityHashMap());
   }
 
@@ -436,7 +443,7 @@ public static <E> Set<E> newIdentityHashSet() {
    * @since 12.0
    */
   @GwtIncompatible // CopyOnWriteArraySet
-  public static <E> CopyOnWriteArraySet<E> newCopyOnWriteArraySet() {
+  public static <E extends @Nullable Object> CopyOnWriteArraySet<E> newCopyOnWriteArraySet() {
     return new CopyOnWriteArraySet<E>();
   }
 
@@ -448,7 +455,8 @@ public static <E> CopyOnWriteArraySet<E> newCopyOnWriteArraySet() {
    * @since 12.0
    */
   @GwtIncompatible // CopyOnWriteArraySet
-  public static <E> CopyOnWriteArraySet<E> newCopyOnWriteArraySet(Iterable<? extends E> elements) {
+  public static <E extends @Nullable Object> CopyOnWriteArraySet<E> newCopyOnWriteArraySet(
+      Iterable<? extends E> elements) {
     // We copy elements to an ArrayList first, rather than incurring the
     // quadratic cost of adding them to the COWAS directly.
     Collection<? extends E> elementsCollection =
@@ -536,7 +544,8 @@ private static <E extends Enum<E>> EnumSet<E> makeComplementByHand(
    * @deprecated Use {@link Collections#newSetFromMap} instead.
    */
   @Deprecated
-  public static <E> Set<E> newSetFromMap(Map<E, Boolean> map) {
+  public static <E extends @Nullable Object> Set<E> newSetFromMap(
+      Map<E, Boolean> map) {
     return Collections.newSetFromMap(map);
   }
 
@@ -549,7 +558,7 @@ public static <E> Set<E> newSetFromMap(Map<E, Boolean> map) {
    *
    * @since 2.0
    */
-  public abstract static class SetView<E> extends AbstractSet<E> {
+  public abstract static class SetView<E extends @Nullable Object> extends AbstractSet<E> {
     private SetView() {} // no subclasses but our own
 
     /**
@@ -560,6 +569,7 @@ private SetView() {} // no subclasses but our own
      * nonstandard notion of equivalence, for example if it is a {@link TreeSet} using a comparator
      * that is inconsistent with {@link Object#equals(Object)}.
      */
+    @SuppressWarnings("nullness") // Unsafe, but we can't fix it now.
     public ImmutableSet<E> immutableCopy() {
       return ImmutableSet.copyOf(this);
     }
@@ -588,7 +598,8 @@ public <S extends Set<E>> S copyInto(S set) {
     @CanIgnoreReturnValue
     @Deprecated
     @Override
-    public final boolean add(E e) {
+    @DoNotCall("Always throws UnsupportedOperationException")
+    public final boolean add(@ParametricNullness E e) {
       throw new UnsupportedOperationException();
     }
 
@@ -601,7 +612,8 @@ public final boolean add(E e) {
     @CanIgnoreReturnValue
     @Deprecated
     @Override
-    public final boolean remove(Object object) {
+    @DoNotCall("Always throws UnsupportedOperationException")
+    public final boolean remove(@CheckForNull Object object) {
       throw new UnsupportedOperationException();
     }
 
@@ -614,6 +626,7 @@ public final boolean remove(Object object) {
     @CanIgnoreReturnValue
     @Deprecated
     @Override
+    @DoNotCall("Always throws UnsupportedOperationException")
     public final boolean addAll(Collection<? extends E> newElements) {
       throw new UnsupportedOperationException();
     }
@@ -627,6 +640,7 @@ public final boolean addAll(Collection<? extends E> newElements) {
     @CanIgnoreReturnValue
     @Deprecated
     @Override
+    @DoNotCall("Always throws UnsupportedOperationException")
     public final boolean removeAll(Collection<?> oldElements) {
       throw new UnsupportedOperationException();
     }
@@ -640,6 +654,7 @@ public final boolean removeAll(Collection<?> oldElements) {
     @CanIgnoreReturnValue
     @Deprecated
     @Override
+    @DoNotCall("Always throws UnsupportedOperationException")
     public final boolean removeIf(java.util.function.Predicate<? super E> filter) {
       throw new UnsupportedOperationException();
     }
@@ -653,6 +668,7 @@ public final boolean removeIf(java.util.function.Predicate<? super E> filter) {
     @CanIgnoreReturnValue
     @Deprecated
     @Override
+    @DoNotCall("Always throws UnsupportedOperationException")
     public final boolean retainAll(Collection<?> elementsToKeep) {
       throw new UnsupportedOperationException();
     }
@@ -665,6 +681,7 @@ public final boolean retainAll(Collection<?> elementsToKeep) {
      */
     @Deprecated
     @Override
+    @DoNotCall("Always throws UnsupportedOperationException")
     public final void clear() {
       throw new UnsupportedOperationException();
     }
@@ -685,10 +702,11 @@ public final void clear() {
    * that is not contained in {@code set1}.
    *
    * <p>Results are undefined if {@code set1} and {@code set2} are sets based on different
-   * equivalence relations (as {@link HashSet}, {@link TreeSet}, and the {@link Map#keySet} of an
-   * {@code IdentityHashMap} all are).
+   * equivalence relations, for example if {@code set1} is a {@link HashSet} and {@code set2} is a
+   * {@link TreeSet} or the {@link Map#keySet} of an {@code IdentityHashMap}.
    */
-  public static <E> SetView<E> union(final Set<? extends E> set1, final Set<? extends E> set2) {
+  public static <E extends @Nullable Object> SetView<E> union(
+      final Set<? extends E> set1, final Set<? extends E> set2) {
     checkNotNull(set1, "set1");
     checkNotNull(set2, "set2");
 
@@ -718,6 +736,7 @@ public UnmodifiableIterator<E> iterator() {
           final Iterator<? extends E> itr2 = set2.iterator();
 
           @Override
+          @CheckForNull
           protected E computeNext() {
             if (itr1.hasNext()) {
               return itr1.next();
@@ -735,7 +754,7 @@ protected E computeNext() {
 
       @Override
       public Stream<E> stream() {
-        return Stream.concat(set1.stream(), set2.stream().filter(e -> !set1.contains(e)));
+        return Stream.concat(set1.stream(), set2.stream().filter((E e) -> !set1.contains(e)));
       }
 
       @Override
@@ -744,7 +763,7 @@ public Stream<E> parallelStream() {
       }
 
       @Override
-      public boolean contains(Object object) {
+      public boolean contains(@CheckForNull Object object) {
         return set1.contains(object) || set2.contains(object);
       }
 
@@ -756,6 +775,7 @@ public <S extends Set<E>> S copyInto(S set) {
       }
 
       @Override
+      @SuppressWarnings("nullness") // see supertype
       public ImmutableSet<E> immutableCopy() {
         return new ImmutableSet.Builder<E>().addAll(set1).addAll(set2).build();
       }
@@ -768,8 +788,8 @@ public ImmutableSet<E> immutableCopy() {
    * matches that of {@code set1}.
    *
    * <p>Results are undefined if {@code set1} and {@code set2} are sets based on different
-   * equivalence relations (as {@code HashSet}, {@code TreeSet}, and the keySet of an {@code
-   * IdentityHashMap} all are).
+   * equivalence relations, for example if {@code set1} is a {@link HashSet} and {@code set2} is a
+   * {@link TreeSet} or the {@link Map#keySet} of an {@code IdentityHashMap}.
    *
    * <p><b>Note:</b> The returned view performs slightly better when {@code set1} is the smaller of
    * the two sets. If you have reason to believe one of your sets will generally be smaller than the
@@ -789,7 +809,8 @@ public ImmutableSet<E> immutableCopy() {
    *
    * <p>This is unfortunate, but should come up only very rarely.
    */
-  public static <E> SetView<E> intersection(final Set<E> set1, final Set<?> set2) {
+  public static <E extends @Nullable Object> SetView<E> intersection(
+      final Set<E> set1, final Set<?> set2) {
     checkNotNull(set1, "set1");
     checkNotNull(set2, "set2");
 
@@ -800,6 +821,7 @@ public UnmodifiableIterator<E> iterator() {
           final Iterator<E> itr = set1.iterator();
 
           @Override
+          @CheckForNull
           protected E computeNext() {
             while (itr.hasNext()) {
               E e = itr.next();
@@ -839,7 +861,7 @@ public boolean isEmpty() {
       }
 
       @Override
-      public boolean contains(Object object) {
+      public boolean contains(@CheckForNull Object object) {
         return set1.contains(object) && set2.contains(object);
       }
 
@@ -857,10 +879,11 @@ public boolean containsAll(Collection<?> collection) {
    * order of the returned set matches that of {@code set1}.
    *
    * <p>Results are undefined if {@code set1} and {@code set2} are sets based on different
-   * equivalence relations (as {@code HashSet}, {@code TreeSet}, and the keySet of an {@code
-   * IdentityHashMap} all are).
+   * equivalence relations, for example if {@code set1} is a {@link HashSet} and {@code set2} is a
+   * {@link TreeSet} or the {@link Map#keySet} of an {@code IdentityHashMap}.
    */
-  public static <E> SetView<E> difference(final Set<E> set1, final Set<?> set2) {
+  public static <E extends @Nullable Object> SetView<E> difference(
+      final Set<E> set1, final Set<?> set2) {
     checkNotNull(set1, "set1");
     checkNotNull(set2, "set2");
 
@@ -871,6 +894,7 @@ public UnmodifiableIterator<E> iterator() {
           final Iterator<E> itr = set1.iterator();
 
           @Override
+          @CheckForNull
           protected E computeNext() {
             while (itr.hasNext()) {
               E e = itr.next();
@@ -910,7 +934,7 @@ public boolean isEmpty() {
       }
 
       @Override
-      public boolean contains(Object element) {
+      public boolean contains(@CheckForNull Object element) {
         return set1.contains(element) && !set2.contains(element);
       }
     };
@@ -922,12 +946,12 @@ public boolean contains(Object element) {
    * both. The iteration order of the returned set is undefined.
    *
    * <p>Results are undefined if {@code set1} and {@code set2} are sets based on different
-   * equivalence relations (as {@code HashSet}, {@code TreeSet}, and the keySet of an {@code
-   * IdentityHashMap} all are).
+   * equivalence relations, for example if {@code set1} is a {@link HashSet} and {@code set2} is a
+   * {@link TreeSet} or the {@link Map#keySet} of an {@code IdentityHashMap}.
    *
    * @since 3.0
    */
-  public static <E> SetView<E> symmetricDifference(
+  public static <E extends @Nullable Object> SetView<E> symmetricDifference(
       final Set<? extends E> set1, final Set<? extends E> set2) {
     checkNotNull(set1, "set1");
     checkNotNull(set2, "set2");
@@ -939,6 +963,7 @@ public UnmodifiableIterator<E> iterator() {
         final Iterator<? extends E> itr2 = set2.iterator();
         return new AbstractIterator<E>() {
           @Override
+          @CheckForNull
           public E computeNext() {
             while (itr1.hasNext()) {
               E elem1 = itr1.next();
@@ -979,7 +1004,7 @@ public boolean isEmpty() {
       }
 
       @Override
-      public boolean contains(Object element) {
+      public boolean contains(@CheckForNull Object element) {
         return set1.contains(element) ^ set2.contains(element);
       }
     };
@@ -1012,7 +1037,8 @@ public boolean contains(Object element) {
    * you to migrate to streams.
    */
   // TODO(kevinb): how to omit that last sentence when building GWT javadoc?
-  public static <E> Set<E> filter(Set<E> unfiltered, Predicate<? super E> predicate) {
+  public static <E extends @Nullable Object> Set<E> filter(
+      Set<E> unfiltered, Predicate<? super E> predicate) {
     if (unfiltered instanceof SortedSet) {
       return filter((SortedSet<E>) unfiltered, predicate);
     }
@@ -1051,7 +1077,8 @@ public static <E> Set<E> filter(Set<E> unfiltered, Predicate<? super E> predicat
    *
    * @since 11.0
    */
-  public static <E> SortedSet<E> filter(SortedSet<E> unfiltered, Predicate<? super E> predicate) {
+  public static <E extends @Nullable Object> SortedSet<E> filter(
+      SortedSet<E> unfiltered, Predicate<? super E> predicate) {
     if (unfiltered instanceof FilteredSet) {
       // Support clear(), removeAll(), and retainAll() when filtering a filtered
       // collection.
@@ -1089,7 +1116,7 @@ public static <E> SortedSet<E> filter(SortedSet<E> unfiltered, Predicate<? super
    */
   @GwtIncompatible // NavigableSet
   @SuppressWarnings("unchecked")
-  public static <E> NavigableSet<E> filter(
+  public static <E extends @Nullable Object> NavigableSet<E> filter(
       NavigableSet<E> unfiltered, Predicate<? super E> predicate) {
     if (unfiltered instanceof FilteredSet) {
       // Support clear(), removeAll(), and retainAll() when filtering a filtered
@@ -1102,13 +1129,14 @@ public static <E> NavigableSet<E> filter(
     return new FilteredNavigableSet<E>(checkNotNull(unfiltered), checkNotNull(predicate));
   }
 
-  private static class FilteredSet<E> extends FilteredCollection<E> implements Set<E> {
+  private static class FilteredSet<E extends @Nullable Object> extends FilteredCollection<E>
+      implements Set<E> {
     FilteredSet(Set<E> unfiltered, Predicate<? super E> predicate) {
       super(unfiltered, predicate);
     }
 
     @Override
-    public boolean equals(@Nullable Object object) {
+    public boolean equals(@CheckForNull Object object) {
       return equalsImpl(this, object);
     }
 
@@ -1118,39 +1146,43 @@ public int hashCode() {
     }
   }
 
-  private static class FilteredSortedSet<E> extends FilteredSet<E> implements SortedSet<E> {
+  private static class FilteredSortedSet<E extends @Nullable Object> extends FilteredSet<E>
+      implements SortedSet<E> {
 
     FilteredSortedSet(SortedSet<E> unfiltered, Predicate<? super E> predicate) {
       super(unfiltered, predicate);
     }
 
     @Override
+    @CheckForNull
     public Comparator<? super E> comparator() {
       return ((SortedSet<E>) unfiltered).comparator();
     }
 
     @Override
-    public SortedSet<E> subSet(E fromElement, E toElement) {
+    public SortedSet<E> subSet(@ParametricNullness E fromElement, @ParametricNullness E toElement) {
       return new FilteredSortedSet<E>(
           ((SortedSet<E>) unfiltered).subSet(fromElement, toElement), predicate);
     }
 
     @Override
-    public SortedSet<E> headSet(E toElement) {
+    public SortedSet<E> headSet(@ParametricNullness E toElement) {
       return new FilteredSortedSet<E>(((SortedSet<E>) unfiltered).headSet(toElement), predicate);
     }
 
     @Override
-    public SortedSet<E> tailSet(E fromElement) {
+    public SortedSet<E> tailSet(@ParametricNullness E fromElement) {
       return new FilteredSortedSet<E>(((SortedSet<E>) unfiltered).tailSet(fromElement), predicate);
     }
 
     @Override
+    @ParametricNullness
     public E first() {
       return Iterators.find(unfiltered.iterator(), predicate);
     }
 
     @Override
+    @ParametricNullness
     public E last() {
       SortedSet<E> sortedUnfiltered = (SortedSet<E>) unfiltered;
       while (true) {
@@ -1164,7 +1196,7 @@ public E last() {
   }
 
   @GwtIncompatible // NavigableSet
-  private static class FilteredNavigableSet<E> extends FilteredSortedSet<E>
+  private static class FilteredNavigableSet<E extends @Nullable Object> extends FilteredSortedSet<E>
       implements NavigableSet<E> {
     FilteredNavigableSet(NavigableSet<E> unfiltered, Predicate<? super E> predicate) {
       super(unfiltered, predicate);
@@ -1175,31 +1207,37 @@ NavigableSet<E> unfiltered() {
     }
 
     @Override
-    public @Nullable E lower(E e) {
+    @CheckForNull
+    public E lower(@ParametricNullness E e) {
       return Iterators.find(unfiltered().headSet(e, false).descendingIterator(), predicate, null);
     }
 
     @Override
-    public @Nullable E floor(E e) {
+    @CheckForNull
+    public E floor(@ParametricNullness E e) {
       return Iterators.find(unfiltered().headSet(e, true).descendingIterator(), predicate, null);
     }
 
     @Override
-    public E ceiling(E e) {
+    @CheckForNull
+    public E ceiling(@ParametricNullness E e) {
       return Iterables.find(unfiltered().tailSet(e, true), predicate, null);
     }
 
     @Override
-    public E higher(E e) {
+    @CheckForNull
+    public E higher(@ParametricNullness E e) {
       return Iterables.find(unfiltered().tailSet(e, false), predicate, null);
     }
 
     @Override
+    @CheckForNull
     public E pollFirst() {
       return Iterables.removeFirstMatching(unfiltered(), predicate);
     }
 
     @Override
+    @CheckForNull
     public E pollLast() {
       return Iterables.removeFirstMatching(unfiltered().descendingSet(), predicate);
     }
@@ -1215,24 +1253,28 @@ public Iterator<E> descendingIterator() {
     }
 
     @Override
+    @ParametricNullness
     public E last() {
       return Iterators.find(unfiltered().descendingIterator(), predicate);
     }
 
     @Override
     public NavigableSet<E> subSet(
-        E fromElement, boolean fromInclusive, E toElement, boolean toInclusive) {
+        @ParametricNullness E fromElement,
+        boolean fromInclusive,
+        @ParametricNullness E toElement,
+        boolean toInclusive) {
       return filter(
           unfiltered().subSet(fromElement, fromInclusive, toElement, toInclusive), predicate);
     }
 
     @Override
-    public NavigableSet<E> headSet(E toElement, boolean inclusive) {
+    public NavigableSet<E> headSet(@ParametricNullness E toElement, boolean inclusive) {
       return filter(unfiltered().headSet(toElement, inclusive), predicate);
     }
 
     @Override
-    public NavigableSet<E> tailSet(E fromElement, boolean inclusive) {
+    public NavigableSet<E> tailSet(@ParametricNullness E fromElement, boolean inclusive) {
       return filter(unfiltered().tailSet(fromElement, inclusive), predicate);
     }
   }
@@ -1398,7 +1440,7 @@ protected Collection<List<E>> delegate() {
     }
 
     @Override
-    public boolean contains(@Nullable Object object) {
+    public boolean contains(@CheckForNull Object object) {
       if (!(object instanceof List)) {
         return false;
       }
@@ -1417,7 +1459,7 @@ public boolean contains(@Nullable Object object) {
     }
 
     @Override
-    public boolean equals(@Nullable Object object) {
+    public boolean equals(@CheckForNull Object object) {
       // Warning: this is broken if size() == 0, so it is critical that we
       // substitute an empty ImmutableSet to the user in place of this
       if (object instanceof CartesianSet) {
@@ -1517,7 +1559,7 @@ public int size() {
     }
 
     @Override
-    public boolean contains(@Nullable Object o) {
+    public boolean contains(@CheckForNull Object o) {
       Integer index = inputSet.get(o);
       return index != null && (mask & (1 << index)) != 0;
     }
@@ -1553,7 +1595,7 @@ protected Set<E> get(final int setBits) {
     }
 
     @Override
-    public boolean contains(@Nullable Object obj) {
+    public boolean contains(@CheckForNull Object obj) {
       if (obj instanceof Set) {
         Set<?> set = (Set<?>) obj;
         return inputSet.keySet().containsAll(set);
@@ -1562,7 +1604,7 @@ public boolean contains(@Nullable Object obj) {
     }
 
     @Override
-    public boolean equals(@Nullable Object obj) {
+    public boolean equals(@CheckForNull Object obj) {
       if (obj instanceof PowerSet) {
         PowerSet<?> that = (PowerSet<?>) obj;
         return inputSet.keySet().equals(that.inputSet.keySet());
@@ -1622,7 +1664,7 @@ public static <E> Set<Set<E>> combinations(Set<E> set, final int size) {
     }
     return new AbstractSet<Set<E>>() {
       @Override
-      public boolean contains(@Nullable Object o) {
+      public boolean contains(@CheckForNull Object o) {
         if (o instanceof Set) {
           Set<?> s = (Set<?>) o;
           return s.size() == size && index.keySet().containsAll(s);
@@ -1636,6 +1678,7 @@ public Iterator<Set<E>> iterator() {
           final BitSet bits = new BitSet(index.size());
 
           @Override
+          @CheckForNull
           protected Set<E> computeNext() {
             if (bits.isEmpty()) {
               bits.set(0, size);
@@ -1667,7 +1710,7 @@ protected Set<E> computeNext() {
             final BitSet copy = (BitSet) bits.clone();
             return new AbstractSet<E>() {
               @Override
-              public boolean contains(@Nullable Object o) {
+              public boolean contains(@CheckForNull Object o) {
                 Integer i = index.get(o);
                 return i != null && copy.get(i);
               }
@@ -1678,6 +1721,7 @@ public Iterator<E> iterator() {
                   int i = -1;
 
                   @Override
+                  @CheckForNull
                   protected E computeNext() {
                     i = copy.nextSetBit(i + 1);
                     if (i == -1) {
@@ -1723,7 +1767,7 @@ static int hashCodeImpl(Set<?> s) {
   }
 
   /** An implementation for {@link Set#equals(Object)}. */
-  static boolean equalsImpl(Set<?> s, @Nullable Object object) {
+  static boolean equalsImpl(Set<?> s, @CheckForNull Object object) {
     if (s == object) {
       return true;
     }
@@ -1752,15 +1796,16 @@ static boolean equalsImpl(Set<?> s, @Nullable Object object) {
    * @return an unmodifiable view of the specified navigable set
    * @since 12.0
    */
-  public static <E> NavigableSet<E> unmodifiableNavigableSet(NavigableSet<E> set) {
+  public static <E extends @Nullable Object> NavigableSet<E> unmodifiableNavigableSet(
+      NavigableSet<E> set) {
     if (set instanceof ImmutableCollection || set instanceof UnmodifiableNavigableSet) {
       return set;
     }
     return new UnmodifiableNavigableSet<E>(set);
   }
 
-  static final class UnmodifiableNavigableSet<E> extends ForwardingSortedSet<E>
-      implements NavigableSet<E>, Serializable {
+  static final class UnmodifiableNavigableSet<E extends @Nullable Object>
+      extends ForwardingSortedSet<E> implements NavigableSet<E>, Serializable {
     private final NavigableSet<E> delegate;
     private final SortedSet<E> unmodifiableDelegate;
 
@@ -1797,36 +1842,42 @@ public void forEach(Consumer<? super E> action) {
     }
 
     @Override
-    public E lower(E e) {
+    @CheckForNull
+    public E lower(@ParametricNullness E e) {
       return delegate.lower(e);
     }
 
     @Override
-    public E floor(E e) {
+    @CheckForNull
+    public E floor(@ParametricNullness E e) {
       return delegate.floor(e);
     }
 
     @Override
-    public E ceiling(E e) {
+    @CheckForNull
+    public E ceiling(@ParametricNullness E e) {
       return delegate.ceiling(e);
     }
 
     @Override
-    public E higher(E e) {
+    @CheckForNull
+    public E higher(@ParametricNullness E e) {
       return delegate.higher(e);
     }
 
     @Override
+    @CheckForNull
     public E pollFirst() {
       throw new UnsupportedOperationException();
     }
 
     @Override
+    @CheckForNull
     public E pollLast() {
       throw new UnsupportedOperationException();
     }
 
-    private transient @Nullable UnmodifiableNavigableSet<E> descendingSet;
+    @CheckForNull private transient UnmodifiableNavigableSet<E> descendingSet;
 
     @Override
     public NavigableSet<E> descendingSet() {
@@ -1845,18 +1896,21 @@ public Iterator<E> descendingIterator() {
 
     @Override
     public NavigableSet<E> subSet(
-        E fromElement, boolean fromInclusive, E toElement, boolean toInclusive) {
+        @ParametricNullness E fromElement,
+        boolean fromInclusive,
+        @ParametricNullness E toElement,
+        boolean toInclusive) {
       return unmodifiableNavigableSet(
           delegate.subSet(fromElement, fromInclusive, toElement, toInclusive));
     }
 
     @Override
-    public NavigableSet<E> headSet(E toElement, boolean inclusive) {
+    public NavigableSet<E> headSet(@ParametricNullness E toElement, boolean inclusive) {
       return unmodifiableNavigableSet(delegate.headSet(toElement, inclusive));
     }
 
     @Override
-    public NavigableSet<E> tailSet(E fromElement, boolean inclusive) {
+    public NavigableSet<E> tailSet(@ParametricNullness E fromElement, boolean inclusive) {
       return unmodifiableNavigableSet(delegate.tailSet(fromElement, inclusive));
     }
 
@@ -1909,7 +1963,8 @@ public NavigableSet<E> tailSet(E fromElement, boolean inclusive) {
    * @since 13.0
    */
   @GwtIncompatible // NavigableSet
-  public static <E> NavigableSet<E> synchronizedNavigableSet(NavigableSet<E> navigableSet) {
+  public static <E extends @Nullable Object> NavigableSet<E> synchronizedNavigableSet(
+      NavigableSet<E> navigableSet) {
     return Synchronized.navigableSet(navigableSet);
   }
 
@@ -1942,7 +1997,7 @@ static boolean removeAllImpl(Set<?> set, Collection<?> collection) {
   }
 
   @GwtIncompatible // NavigableSet
-  static class DescendingSet<E> extends ForwardingNavigableSet<E> {
+  static class DescendingSet<E extends @Nullable Object> extends ForwardingNavigableSet<E> {
     private final NavigableSet<E> forward;
 
     DescendingSet(NavigableSet<E> forward) {
@@ -1955,31 +2010,37 @@ protected NavigableSet<E> delegate() {
     }
 
     @Override
-    public E lower(E e) {
+    @CheckForNull
+    public E lower(@ParametricNullness E e) {
       return forward.higher(e);
     }
 
     @Override
-    public E floor(E e) {
+    @CheckForNull
+    public E floor(@ParametricNullness E e) {
       return forward.ceiling(e);
     }
 
     @Override
-    public E ceiling(E e) {
+    @CheckForNull
+    public E ceiling(@ParametricNullness E e) {
       return forward.floor(e);
     }
 
     @Override
-    public E higher(E e) {
+    @CheckForNull
+    public E higher(@ParametricNullness E e) {
       return forward.lower(e);
     }
 
     @Override
+    @CheckForNull
     public E pollFirst() {
       return forward.pollLast();
     }
 
     @Override
+    @CheckForNull
     public E pollLast() {
       return forward.pollFirst();
     }
@@ -1996,32 +2057,35 @@ public Iterator<E> descendingIterator() {
 
     @Override
     public NavigableSet<E> subSet(
-        E fromElement, boolean fromInclusive, E toElement, boolean toInclusive) {
+        @ParametricNullness E fromElement,
+        boolean fromInclusive,
+        @ParametricNullness E toElement,
+        boolean toInclusive) {
       return forward.subSet(toElement, toInclusive, fromElement, fromInclusive).descendingSet();
     }
 
     @Override
-    public SortedSet<E> subSet(E fromElement, E toElement) {
+    public SortedSet<E> subSet(@ParametricNullness E fromElement, @ParametricNullness E toElement) {
       return standardSubSet(fromElement, toElement);
     }
 
     @Override
-    public NavigableSet<E> headSet(E toElement, boolean inclusive) {
+    public NavigableSet<E> headSet(@ParametricNullness E toElement, boolean inclusive) {
       return forward.tailSet(toElement, inclusive).descendingSet();
     }
 
     @Override
-    public SortedSet<E> headSet(E toElement) {
+    public SortedSet<E> headSet(@ParametricNullness E toElement) {
       return standardHeadSet(toElement);
     }
 
     @Override
-    public NavigableSet<E> tailSet(E fromElement, boolean inclusive) {
+    public NavigableSet<E> tailSet(@ParametricNullness E fromElement, boolean inclusive) {
       return forward.headSet(fromElement, inclusive).descendingSet();
     }
 
     @Override
-    public SortedSet<E> tailSet(E fromElement) {
+    public SortedSet<E> tailSet(@ParametricNullness E fromElement) {
       return standardTailSet(fromElement);
     }
 
@@ -2037,16 +2101,18 @@ public Comparator<? super E> comparator() {
     }
 
     // If we inline this, we get a javac error.
-    private static <T> Ordering<T> reverse(Comparator<T> forward) {
+    private static <T extends @Nullable Object> Ordering<T> reverse(Comparator<T> forward) {
       return Ordering.from(forward).reverse();
     }
 
     @Override
+    @ParametricNullness
     public E first() {
       return forward.last();
     }
 
     @Override
+    @ParametricNullness
     public E last() {
       return forward.first();
     }
@@ -2057,12 +2123,13 @@ public Iterator<E> iterator() {
     }
 
     @Override
-    public Object[] toArray() {
+    public @Nullable Object[] toArray() {
       return standardToArray();
     }
 
     @Override
-    public <T> T[] toArray(T[] array) {
+    @SuppressWarnings("nullness") // b/192354773 in our checker affects toArray declarations
+    public <T extends @Nullable Object> T[] toArray(T[] array) {
       return standardToArray(array);
     }
 
diff --git a/guava/src/com/google/common/collect/SingletonImmutableBiMap.java b/guava/src/com/google/common/collect/SingletonImmutableBiMap.java
index ea6f275677d3..c5fb2b29892a 100644
--- a/guava/src/com/google/common/collect/SingletonImmutableBiMap.java
+++ b/guava/src/com/google/common/collect/SingletonImmutableBiMap.java
@@ -23,7 +23,7 @@
 import com.google.errorprone.annotations.concurrent.LazyInit;
 import com.google.j2objc.annotations.RetainedWith;
 import java.util.function.BiConsumer;
-import org.checkerframework.checker.nullness.qual.Nullable;
+import javax.annotation.CheckForNull;
 
 /**
  * Implementation of {@link ImmutableMap} with exactly one entry.
@@ -33,6 +33,7 @@
  */
 @GwtCompatible(serializable = true, emulated = true)
 @SuppressWarnings("serial") // uses writeReplace(), not default serialization
+@ElementTypesAreNonnullByDefault
 final class SingletonImmutableBiMap<K, V> extends ImmutableBiMap<K, V> {
 
   final transient K singleKey;
@@ -52,7 +53,8 @@ private SingletonImmutableBiMap(K singleKey, V singleValue, ImmutableBiMap<V, K>
   }
 
   @Override
-  public V get(@Nullable Object key) {
+  @CheckForNull
+  public V get(@CheckForNull Object key) {
     return singleKey.equals(key) ? singleValue : null;
   }
 
@@ -67,12 +69,12 @@ public void forEach(BiConsumer<? super K, ? super V> action) {
   }
 
   @Override
-  public boolean containsKey(@Nullable Object key) {
+  public boolean containsKey(@CheckForNull Object key) {
     return singleKey.equals(key);
   }
 
   @Override
-  public boolean containsValue(@Nullable Object value) {
+  public boolean containsValue(@CheckForNull Object value) {
     return singleValue.equals(value);
   }
 
@@ -91,8 +93,8 @@ ImmutableSet<K> createKeySet() {
     return ImmutableSet.of(singleKey);
   }
 
-  private final transient @Nullable ImmutableBiMap<V, K> inverse;
-  @LazyInit @RetainedWith private transient @Nullable ImmutableBiMap<V, K> lazyInverse;
+  @CheckForNull private final transient ImmutableBiMap<V, K> inverse;
+  @LazyInit @RetainedWith @CheckForNull private transient ImmutableBiMap<V, K> lazyInverse;
 
   @Override
   public ImmutableBiMap<V, K> inverse() {
diff --git a/guava/src/com/google/common/collect/SingletonImmutableList.java b/guava/src/com/google/common/collect/SingletonImmutableList.java
index b08dc60c2694..c0d388e821d9 100644
--- a/guava/src/com/google/common/collect/SingletonImmutableList.java
+++ b/guava/src/com/google/common/collect/SingletonImmutableList.java
@@ -22,7 +22,7 @@
 import com.google.common.base.Preconditions;
 import java.util.Collections;
 import java.util.Spliterator;
-import javax.annotation.Nullable;
+import org.checkerframework.checker.nullness.qual.Nullable;
 import org.checkerframework.dataflow.qual.Pure;
 import org.checkerframework.dataflow.qual.SideEffectFree;
 import org.checkerframework.framework.qual.AnnotatedFor;
@@ -35,6 +35,7 @@
 @AnnotatedFor({"nullness"})
 @GwtCompatible(serializable = true, emulated = true)
 @SuppressWarnings("serial") // uses writeReplace(), not default serialization
+@ElementTypesAreNonnullByDefault
 final class SingletonImmutableList<E> extends ImmutableList<E> {
 
   final transient E element;
diff --git a/guava/src/com/google/common/collect/SingletonImmutableSet.java b/guava/src/com/google/common/collect/SingletonImmutableSet.java
index b73682366ba8..cbfcee3560f7 100644
--- a/guava/src/com/google/common/collect/SingletonImmutableSet.java
+++ b/guava/src/com/google/common/collect/SingletonImmutableSet.java
@@ -19,9 +19,11 @@
 import com.google.common.annotations.GwtCompatible;
 import com.google.common.base.Preconditions;
 import com.google.errorprone.annotations.concurrent.LazyInit;
+import javax.annotation.CheckForNull;
 import org.checkerframework.checker.nullness.qual.Nullable;
 import org.checkerframework.dataflow.qual.Pure;
 import org.checkerframework.framework.qual.AnnotatedFor;
+import org.checkerframework.checker.nullness.qual.Nullable;
 
 /**
  * Implementation of {@link ImmutableSet} with exactly one element.
@@ -32,29 +34,17 @@
 @AnnotatedFor({"nullness"})
 @GwtCompatible(serializable = true, emulated = true)
 @SuppressWarnings("serial") // uses writeReplace(), not default serialization
+@ElementTypesAreNonnullByDefault
 final class SingletonImmutableSet<E> extends ImmutableSet<E> {
+  // We deliberately avoid caching the asList and hashCode here, to ensure that with
+  // compressed oops, a SingletonImmutableSet packs all the way down to the optimal 16 bytes.
 
   final transient E element;
-  // This is transient because it will be recalculated on the first
-  // call to hashCode().
-  //
-  // A race condition is avoided since threads will either see that the value
-  // is zero and recalculate it themselves, or two threads will see it at
-  // the same time, and both recalculate it.  If the cachedHashCode is 0,
-  // it will always be recalculated, unfortunately.
-  @LazyInit private transient int cachedHashCode;
 
   SingletonImmutableSet(E element) {
     this.element = Preconditions.checkNotNull(element);
   }
 
-  @Pure
-  SingletonImmutableSet(E element, int hashCode) {
-    // Guaranteed to be non-null by the presence of the pre-computed hash code.
-    this.element = element;
-    cachedHashCode = hashCode;
-  }
-
   @Pure
   @Override
   public int size() {
@@ -63,7 +53,7 @@ public int size() {
 
   @Pure
   @Override
-  public boolean contains(@Nullable Object target) {
+  public boolean contains(@CheckForNull Object target) {
     return element.equals(target);
   }
 
@@ -73,7 +63,7 @@ public UnmodifiableIterator<E> iterator() {
   }
 
   @Override
-  ImmutableList<E> createAsList() {
+  public ImmutableList<E> asList() {
     return ImmutableList.of(element);
   }
 
@@ -83,7 +73,7 @@ boolean isPartialView() {
   }
 
   @Override
-  int copyIntoArray(Object[] dst, int offset) {
+  int copyIntoArray(@Nullable Object[] dst, int offset) {
     dst[offset] = element;
     return offset + 1;
   }
@@ -91,18 +81,7 @@ int copyIntoArray(Object[] dst, int offset) {
   @Pure
   @Override
   public final int hashCode() {
-    // Racy single-check.
-    int code = cachedHashCode;
-    if (code == 0) {
-      cachedHashCode = code = element.hashCode();
-    }
-    return code;
-  }
-
-  @Pure
-  @Override
-  boolean isHashCodeFast() {
-    return cachedHashCode != 0;
+    return element.hashCode();
   }
 
   @Pure
diff --git a/guava/src/com/google/common/collect/SingletonImmutableTable.java b/guava/src/com/google/common/collect/SingletonImmutableTable.java
index 58a182cccd3e..cfaeadb41df7 100644
--- a/guava/src/com/google/common/collect/SingletonImmutableTable.java
+++ b/guava/src/com/google/common/collect/SingletonImmutableTable.java
@@ -27,6 +27,7 @@
  * @author Gregory Kick
  */
 @GwtCompatible
+@ElementTypesAreNonnullByDefault
 class SingletonImmutableTable<R, C, V> extends ImmutableTable<R, C, V> {
   final R singleRowKey;
   final C singleColumnKey;
diff --git a/guava/src/com/google/common/collect/SortedIterable.java b/guava/src/com/google/common/collect/SortedIterable.java
index d46e8afcd9c5..64ec08ef315b 100644
--- a/guava/src/com/google/common/collect/SortedIterable.java
+++ b/guava/src/com/google/common/collect/SortedIterable.java
@@ -17,6 +17,7 @@
 import com.google.common.annotations.GwtCompatible;
 import java.util.Comparator;
 import java.util.Iterator;
+import org.checkerframework.checker.nullness.qual.Nullable;
 
 /**
  * An {@code Iterable} whose elements are sorted relative to a {@code Comparator}, typically
@@ -25,7 +26,8 @@
  * @author Louis Wasserman
  */
 @GwtCompatible
-interface SortedIterable<T> extends Iterable<T> {
+@ElementTypesAreNonnullByDefault
+interface SortedIterable<T extends @Nullable Object> extends Iterable<T> {
   /**
    * Returns the {@code Comparator} by which the elements of this iterable are ordered, or {@code
    * Ordering.natural()} if the elements are ordered by their natural ordering.
diff --git a/guava/src/com/google/common/collect/SortedIterables.java b/guava/src/com/google/common/collect/SortedIterables.java
index 2c0aa7ccac89..68b231a381e5 100644
--- a/guava/src/com/google/common/collect/SortedIterables.java
+++ b/guava/src/com/google/common/collect/SortedIterables.java
@@ -19,6 +19,7 @@
 import com.google.common.annotations.GwtCompatible;
 import java.util.Comparator;
 import java.util.SortedSet;
+import org.checkerframework.checker.nullness.qual.Nullable;
 
 /**
  * Utilities for dealing with sorted collections of all types.
@@ -26,6 +27,7 @@
  * @author Louis Wasserman
  */
 @GwtCompatible
+@ElementTypesAreNonnullByDefault
 final class SortedIterables {
   private SortedIterables() {}
 
@@ -49,7 +51,8 @@ public static boolean hasSameComparator(Comparator<?> comparator, Iterable<?> el
 
   @SuppressWarnings("unchecked")
   // if sortedSet.comparator() is null, the set must be naturally ordered
-  public static <E> Comparator<? super E> comparator(SortedSet<E> sortedSet) {
+  public static <E extends @Nullable Object> Comparator<? super E> comparator(
+      SortedSet<E> sortedSet) {
     Comparator<? super E> result = sortedSet.comparator();
     if (result == null) {
       result = (Comparator<? super E>) Ordering.natural();
diff --git a/guava/src/com/google/common/collect/SortedLists.java b/guava/src/com/google/common/collect/SortedLists.java
index 812e88ec1f9c..0ebaab20f938 100644
--- a/guava/src/com/google/common/collect/SortedLists.java
+++ b/guava/src/com/google/common/collect/SortedLists.java
@@ -36,6 +36,7 @@
  */
 @GwtCompatible
 @Beta
+@ElementTypesAreNonnullByDefault
 final class SortedLists {
   private SortedLists() {}
 
@@ -50,16 +51,22 @@ enum KeyPresentBehavior {
      */
     ANY_PRESENT {
       @Override
-      <E> int resultIndex(
-          Comparator<? super E> comparator, E key, List<? extends E> list, int foundIndex) {
+      <E extends @Nullable Object> int resultIndex(
+          Comparator<? super E> comparator,
+          @ParametricNullness E key,
+          List<? extends E> list,
+          int foundIndex) {
         return foundIndex;
       }
     },
     /** Return the index of the last list element that compares as equal to the key. */
     LAST_PRESENT {
       @Override
-      <E> int resultIndex(
-          Comparator<? super E> comparator, E key, List<? extends E> list, int foundIndex) {
+      <E extends @Nullable Object> int resultIndex(
+          Comparator<? super E> comparator,
+          @ParametricNullness E key,
+          List<? extends E> list,
+          int foundIndex) {
         // Of course, we have to use binary search to find the precise
         // breakpoint...
         int lower = foundIndex;
@@ -80,8 +87,11 @@ <E> int resultIndex(
     /** Return the index of the first list element that compares as equal to the key. */
     FIRST_PRESENT {
       @Override
-      <E> int resultIndex(
-          Comparator<? super E> comparator, E key, List<? extends E> list, int foundIndex) {
+      <E extends @Nullable Object> int resultIndex(
+          Comparator<? super E> comparator,
+          @ParametricNullness E key,
+          List<? extends E> list,
+          int foundIndex) {
         // Of course, we have to use binary search to find the precise
         // breakpoint...
         int lower = 0;
@@ -106,8 +116,11 @@ <E> int resultIndex(
      */
     FIRST_AFTER {
       @Override
-      public <E> int resultIndex(
-          Comparator<? super E> comparator, E key, List<? extends E> list, int foundIndex) {
+      public <E extends @Nullable Object> int resultIndex(
+          Comparator<? super E> comparator,
+          @ParametricNullness E key,
+          List<? extends E> list,
+          int foundIndex) {
         return LAST_PRESENT.resultIndex(comparator, key, list, foundIndex) + 1;
       }
     },
@@ -117,14 +130,20 @@ public <E> int resultIndex(
      */
     LAST_BEFORE {
       @Override
-      public <E> int resultIndex(
-          Comparator<? super E> comparator, E key, List<? extends E> list, int foundIndex) {
+      public <E extends @Nullable Object> int resultIndex(
+          Comparator<? super E> comparator,
+          @ParametricNullness E key,
+          List<? extends E> list,
+          int foundIndex) {
         return FIRST_PRESENT.resultIndex(comparator, key, list, foundIndex) - 1;
       }
     };
 
-    abstract <E> int resultIndex(
-        Comparator<? super E> comparator, E key, List<? extends E> list, int foundIndex);
+    abstract <E extends @Nullable Object> int resultIndex(
+        Comparator<? super E> comparator,
+        @ParametricNullness E key,
+        List<? extends E> list,
+        int foundIndex);
   }
 
   /**
@@ -196,12 +215,13 @@ public static <E extends Comparable> int binarySearch(
    * <p>Equivalent to {@link #binarySearch(List, Function, Object, Comparator, KeyPresentBehavior,
    * KeyAbsentBehavior)} using {@link Ordering#natural}.
    */
-  public static <E, K extends Comparable> int binarySearch(
+  public static <E extends @Nullable Object, K extends Comparable> int binarySearch(
       List<E> list,
       Function<? super E, K> keyFunction,
-      @Nullable K key,
+      K key,
       KeyPresentBehavior presentBehavior,
       KeyAbsentBehavior absentBehavior) {
+    checkNotNull(key);
     return binarySearch(
         list, keyFunction, key, Ordering.natural(), presentBehavior, absentBehavior);
   }
@@ -213,10 +233,10 @@ public static <E, K extends Comparable> int binarySearch(
    * KeyAbsentBehavior)} using {@link Lists#transform(List, Function) Lists.transform(list,
    * keyFunction)}.
    */
-  public static <E, K> int binarySearch(
+  public static <E extends @Nullable Object, K extends @Nullable Object> int binarySearch(
       List<E> list,
       Function<? super E, K> keyFunction,
-      @Nullable K key,
+      @ParametricNullness K key,
       Comparator<? super K> keyComparator,
       KeyPresentBehavior presentBehavior,
       KeyAbsentBehavior absentBehavior) {
@@ -247,9 +267,9 @@ public static <E, K> int binarySearch(
    * @return the index determined by the {@code KeyPresentBehavior}, if the key is in the list;
    *     otherwise the index determined by the {@code KeyAbsentBehavior}.
    */
-  public static <E> int binarySearch(
+  public static <E extends @Nullable Object> int binarySearch(
       List<? extends E> list,
-      @Nullable E key,
+      @ParametricNullness E key,
       Comparator<? super E> comparator,
       KeyPresentBehavior presentBehavior,
       KeyAbsentBehavior absentBehavior) {
diff --git a/guava/src/com/google/common/collect/SortedMapDifference.java b/guava/src/com/google/common/collect/SortedMapDifference.java
index 4715e93e5c9c..46cac8a3da54 100644
--- a/guava/src/com/google/common/collect/SortedMapDifference.java
+++ b/guava/src/com/google/common/collect/SortedMapDifference.java
@@ -18,6 +18,7 @@
 
 import com.google.common.annotations.GwtCompatible;
 import java.util.SortedMap;
+import org.checkerframework.checker.nullness.qual.Nullable;
 
 /**
  * An object representing the differences between two sorted maps.
@@ -26,7 +27,9 @@
  * @since 8.0
  */
 @GwtCompatible
-public interface SortedMapDifference<K, V> extends MapDifference<K, V> {
+@ElementTypesAreNonnullByDefault
+public interface SortedMapDifference<K extends @Nullable Object, V extends @Nullable Object>
+    extends MapDifference<K, V> {
 
   @Override
   SortedMap<K, V> entriesOnlyOnLeft();
diff --git a/guava/src/com/google/common/collect/SortedMultiset.java b/guava/src/com/google/common/collect/SortedMultiset.java
index 2635b37ede33..7cc512d8ee2e 100644
--- a/guava/src/com/google/common/collect/SortedMultiset.java
+++ b/guava/src/com/google/common/collect/SortedMultiset.java
@@ -22,6 +22,8 @@
 import java.util.Iterator;
 import java.util.NavigableSet;
 import java.util.Set;
+import javax.annotation.CheckForNull;
+import org.checkerframework.checker.nullness.qual.Nullable;
 
 /**
  * A {@link Multiset} which maintains the ordering of its elements, according to either their
@@ -35,14 +37,15 @@
  * Collection} contract, which is specified in terms of {@link Object#equals}.
  *
  * <p>See the Guava User Guide article on <a href=
- * "https://github.com/google/guava/wiki/NewCollectionTypesExplained#multiset"> {@code
- * Multiset}</a>.
+ * "https://github.com/google/guava/wiki/NewCollectionTypesExplained#multiset">{@code Multiset}</a>.
  *
  * @author Louis Wasserman
  * @since 11.0
  */
 @GwtCompatible(emulated = true)
-public interface SortedMultiset<E> extends SortedMultisetBridge<E>, SortedIterable<E> {
+@ElementTypesAreNonnullByDefault
+public interface SortedMultiset<E extends @Nullable Object>
+    extends SortedMultisetBridge<E>, SortedIterable<E> {
   /**
    * Returns the comparator that orders this multiset, or {@link Ordering#natural()} if the natural
    * ordering of the elements is used.
@@ -54,24 +57,28 @@ public interface SortedMultiset<E> extends SortedMultisetBridge<E>, SortedIterab
    * Returns the entry of the first element in this multiset, or {@code null} if this multiset is
    * empty.
    */
+  @CheckForNull
   Entry<E> firstEntry();
 
   /**
    * Returns the entry of the last element in this multiset, or {@code null} if this multiset is
    * empty.
    */
+  @CheckForNull
   Entry<E> lastEntry();
 
   /**
    * Returns and removes the entry associated with the lowest element in this multiset, or returns
    * {@code null} if this multiset is empty.
    */
+  @CheckForNull
   Entry<E> pollFirstEntry();
 
   /**
    * Returns and removes the entry associated with the greatest element in this multiset, or returns
    * {@code null} if this multiset is empty.
    */
+  @CheckForNull
   Entry<E> pollLastEntry();
 
   /**
@@ -115,7 +122,7 @@ public interface SortedMultiset<E> extends SortedMultisetBridge<E>, SortedIterab
    * <p>The returned multiset will throw an {@link IllegalArgumentException} on attempts to add
    * elements outside its range.
    */
-  SortedMultiset<E> headMultiset(E upperBound, BoundType boundType);
+  SortedMultiset<E> headMultiset(@ParametricNullness E upperBound, BoundType boundType);
 
   /**
    * Returns a view of this multiset restricted to the range between {@code lowerBound} and {@code
@@ -130,7 +137,10 @@ public interface SortedMultiset<E> extends SortedMultisetBridge<E>, SortedIterab
    * lowerBoundType).headMultiset(upperBound, upperBoundType)}.
    */
   SortedMultiset<E> subMultiset(
-      E lowerBound, BoundType lowerBoundType, E upperBound, BoundType upperBoundType);
+      @ParametricNullness E lowerBound,
+      BoundType lowerBoundType,
+      @ParametricNullness E upperBound,
+      BoundType upperBoundType);
 
   /**
    * Returns a view of this multiset restricted to the elements greater than {@code lowerBound},
@@ -141,5 +151,5 @@ SortedMultiset<E> subMultiset(
    * <p>The returned multiset will throw an {@link IllegalArgumentException} on attempts to add
    * elements outside its range.
    */
-  SortedMultiset<E> tailMultiset(E lowerBound, BoundType boundType);
+  SortedMultiset<E> tailMultiset(@ParametricNullness E lowerBound, BoundType boundType);
 }
diff --git a/guava/src/com/google/common/collect/SortedMultisetBridge.java b/guava/src/com/google/common/collect/SortedMultisetBridge.java
index 064cb7588f5d..72d50beb692f 100644
--- a/guava/src/com/google/common/collect/SortedMultisetBridge.java
+++ b/guava/src/com/google/common/collect/SortedMultisetBridge.java
@@ -18,6 +18,7 @@
 
 import com.google.common.annotations.GwtIncompatible;
 import java.util.SortedSet;
+import org.checkerframework.checker.nullness.qual.Nullable;
 
 /**
  * Superinterface of {@link SortedMultiset} to introduce a bridge method for {@code elementSet()},
@@ -27,7 +28,8 @@
  * @author Louis Wasserman
  */
 @GwtIncompatible
-interface SortedMultisetBridge<E> extends Multiset<E> {
+@ElementTypesAreNonnullByDefault
+interface SortedMultisetBridge<E extends @Nullable Object> extends Multiset<E> {
   @Override
   SortedSet<E> elementSet();
 }
diff --git a/guava/src/com/google/common/collect/SortedMultisets.java b/guava/src/com/google/common/collect/SortedMultisets.java
index a928959e9c30..f602a42a1145 100644
--- a/guava/src/com/google/common/collect/SortedMultisets.java
+++ b/guava/src/com/google/common/collect/SortedMultisets.java
@@ -28,6 +28,7 @@
 import java.util.NavigableSet;
 import java.util.NoSuchElementException;
 import java.util.SortedSet;
+import javax.annotation.CheckForNull;
 import org.checkerframework.checker.nullness.qual.Nullable;
 
 /**
@@ -36,11 +37,14 @@
  * @author Louis Wasserman
  */
 @GwtCompatible(emulated = true)
+@ElementTypesAreNonnullByDefault
 final class SortedMultisets {
   private SortedMultisets() {}
 
   /** A skeleton implementation for {@link SortedMultiset#elementSet}. */
-  static class ElementSet<E> extends Multisets.ElementSet<E> implements SortedSet<E> {
+  @SuppressWarnings("JdkObsolete") // TODO(b/6160855): Switch GWT emulations to NavigableSet.
+  static class ElementSet<E extends @Nullable Object> extends Multisets.ElementSet<E>
+      implements SortedSet<E> {
     @Weak private final SortedMultiset<E> multiset;
 
     ElementSet(SortedMultiset<E> multiset) {
@@ -63,26 +67,28 @@ public Comparator<? super E> comparator() {
     }
 
     @Override
-    public SortedSet<E> subSet(E fromElement, E toElement) {
+    public SortedSet<E> subSet(@ParametricNullness E fromElement, @ParametricNullness E toElement) {
       return multiset().subMultiset(fromElement, CLOSED, toElement, OPEN).elementSet();
     }
 
     @Override
-    public SortedSet<E> headSet(E toElement) {
+    public SortedSet<E> headSet(@ParametricNullness E toElement) {
       return multiset().headMultiset(toElement, OPEN).elementSet();
     }
 
     @Override
-    public SortedSet<E> tailSet(E fromElement) {
+    public SortedSet<E> tailSet(@ParametricNullness E fromElement) {
       return multiset().tailMultiset(fromElement, CLOSED).elementSet();
     }
 
     @Override
+    @ParametricNullness
     public E first() {
       return getElementOrThrow(multiset().firstEntry());
     }
 
     @Override
+    @ParametricNullness
     public E last() {
       return getElementOrThrow(multiset().lastEntry());
     }
@@ -90,34 +96,39 @@ public E last() {
 
   /** A skeleton navigable implementation for {@link SortedMultiset#elementSet}. */
   @GwtIncompatible // Navigable
-  static class NavigableElementSet<E> extends ElementSet<E> implements NavigableSet<E> {
+  static class NavigableElementSet<E extends @Nullable Object> extends ElementSet<E>
+      implements NavigableSet<E> {
     NavigableElementSet(SortedMultiset<E> multiset) {
       super(multiset);
     }
 
     @Override
-    public E lower(E e) {
+    @CheckForNull
+    public E lower(@ParametricNullness E e) {
       return getElementOrNull(multiset().headMultiset(e, OPEN).lastEntry());
     }
 
     @Override
-    public E floor(E e) {
+    @CheckForNull
+    public E floor(@ParametricNullness E e) {
       return getElementOrNull(multiset().headMultiset(e, CLOSED).lastEntry());
     }
 
     @Override
-    public E ceiling(E e) {
+    @CheckForNull
+    public E ceiling(@ParametricNullness E e) {
       return getElementOrNull(multiset().tailMultiset(e, CLOSED).firstEntry());
     }
 
     @Override
-    public E higher(E e) {
+    @CheckForNull
+    public E higher(@ParametricNullness E e) {
       return getElementOrNull(multiset().tailMultiset(e, OPEN).firstEntry());
     }
 
     @Override
     public NavigableSet<E> descendingSet() {
-      return new NavigableElementSet<E>(multiset().descendingMultiset());
+      return new NavigableElementSet<>(multiset().descendingMultiset());
     }
 
     @Override
@@ -126,19 +137,24 @@ public Iterator<E> descendingIterator() {
     }
 
     @Override
+    @CheckForNull
     public E pollFirst() {
       return getElementOrNull(multiset().pollFirstEntry());
     }
 
     @Override
+    @CheckForNull
     public E pollLast() {
       return getElementOrNull(multiset().pollLastEntry());
     }
 
     @Override
     public NavigableSet<E> subSet(
-        E fromElement, boolean fromInclusive, E toElement, boolean toInclusive) {
-      return new NavigableElementSet<E>(
+        @ParametricNullness E fromElement,
+        boolean fromInclusive,
+        @ParametricNullness E toElement,
+        boolean toInclusive) {
+      return new NavigableElementSet<>(
           multiset()
               .subMultiset(
                   fromElement, BoundType.forBoolean(fromInclusive),
@@ -146,26 +162,27 @@ public NavigableSet<E> subSet(
     }
 
     @Override
-    public NavigableSet<E> headSet(E toElement, boolean inclusive) {
-      return new NavigableElementSet<E>(
+    public NavigableSet<E> headSet(@ParametricNullness E toElement, boolean inclusive) {
+      return new NavigableElementSet<>(
           multiset().headMultiset(toElement, BoundType.forBoolean(inclusive)));
     }
 
     @Override
-    public NavigableSet<E> tailSet(E fromElement, boolean inclusive) {
-      return new NavigableElementSet<E>(
+    public NavigableSet<E> tailSet(@ParametricNullness E fromElement, boolean inclusive) {
+      return new NavigableElementSet<>(
           multiset().tailMultiset(fromElement, BoundType.forBoolean(inclusive)));
     }
   }
 
-  private static <E> E getElementOrThrow(Entry<E> entry) {
+  private static <E extends @Nullable Object> E getElementOrThrow(@CheckForNull Entry<E> entry) {
     if (entry == null) {
       throw new NoSuchElementException();
     }
     return entry.getElement();
   }
 
-  private static <E> E getElementOrNull(@Nullable Entry<E> entry) {
+  @CheckForNull
+  private static <E extends @Nullable Object> E getElementOrNull(@CheckForNull Entry<E> entry) {
     return (entry == null) ? null : entry.getElement();
   }
 }
diff --git a/guava/src/com/google/common/collect/SortedSetMultimap.java b/guava/src/com/google/common/collect/SortedSetMultimap.java
index c6be551d858a..f06d0f705307 100644
--- a/guava/src/com/google/common/collect/SortedSetMultimap.java
+++ b/guava/src/com/google/common/collect/SortedSetMultimap.java
@@ -24,6 +24,7 @@
 import java.util.Set;
 import java.util.SortedMap;
 import java.util.SortedSet;
+import javax.annotation.CheckForNull;
 import org.checkerframework.checker.nullness.qual.Nullable;
 import org.checkerframework.framework.qual.AnnotatedFor;
 
@@ -38,16 +39,21 @@
  * Though the method signature doesn't say so explicitly, the map returned by {@link #asMap} has
  * {@code SortedSet} values.
  *
+ * <p><b>Warning:</b> As in all {@link SetMultimap}s, do not modify either a key <i>or a value</i>
+ * of a {@code SortedSetMultimap} in a way that affects its {@link Object#equals} behavior (or its
+ * position in the order of the values). Undefined behavior and bugs will result.
+ *
  * <p>See the Guava User Guide article on <a href=
- * "https://github.com/google/guava/wiki/NewCollectionTypesExplained#multimap"> {@code
- * Multimap}</a>.
+ * "https://github.com/google/guava/wiki/NewCollectionTypesExplained#multimap">{@code Multimap}</a>.
  *
  * @author Jared Levy
  * @since 2.0
  */
 @GwtCompatible
 @AnnotatedFor({"nullness"})
-public interface SortedSetMultimap<K, V> extends SetMultimap<K, V> {
+@ElementTypesAreNonnullByDefault
+public interface SortedSetMultimap<K extends @Nullable Object, V extends @Nullable Object>
+    extends SetMultimap<K, V> {
   // Following Javadoc copied from Multimap.
 
   /**
@@ -61,7 +67,7 @@ public interface SortedSetMultimap<K, V> extends SetMultimap<K, V> {
    * {@link Multimap} interface.
    */
   @Override
-  SortedSet<V> get(@Nullable K key);
+  SortedSet<V> get(@ParametricNullness K key);
 
   /**
    * Removes all values associated with a given key.
@@ -72,7 +78,7 @@ public interface SortedSetMultimap<K, V> extends SetMultimap<K, V> {
    */
   @CanIgnoreReturnValue
   @Override
-  SortedSet<V> removeAll(@Nullable Object key);
+  SortedSet<V> removeAll(@CheckForNull Object key);
 
   /**
    * Stores a collection of values with the same key, replacing any existing values for that key.
@@ -85,7 +91,7 @@ public interface SortedSetMultimap<K, V> extends SetMultimap<K, V> {
    */
   @CanIgnoreReturnValue
   @Override
-  SortedSet<V> replaceValues(K key, Iterable<? extends V> values);
+  SortedSet<V> replaceValues(@ParametricNullness K key, Iterable<? extends V> values);
 
   /**
    * Returns a map view that associates each key with the corresponding values in the multimap.
@@ -111,5 +117,6 @@ public interface SortedSetMultimap<K, V> extends SetMultimap<K, V> {
    * Returns the comparator that orders the multimap values, with {@code null} indicating that
    * natural ordering is used.
    */
-  @Nullable Comparator<? super V> valueComparator();
+  @CheckForNull
+  Comparator<? super V> valueComparator();
 }
diff --git a/guava/src/com/google/common/collect/SparseImmutableTable.java b/guava/src/com/google/common/collect/SparseImmutableTable.java
index a7fe85debd1c..44881fde7f73 100644
--- a/guava/src/com/google/common/collect/SparseImmutableTable.java
+++ b/guava/src/com/google/common/collect/SparseImmutableTable.java
@@ -14,6 +14,8 @@
 
 package com.google.common.collect;
 
+import static java.util.Objects.requireNonNull;
+
 import com.google.common.annotations.GwtCompatible;
 import com.google.errorprone.annotations.Immutable;
 import java.util.LinkedHashMap;
@@ -23,6 +25,7 @@
 /** A {@code RegularImmutableTable} optimized for sparse data. */
 @GwtCompatible
 @Immutable(containerOf = {"R", "C", "V"})
+@ElementTypesAreNonnullByDefault
 final class SparseImmutableTable<R, C, V> extends RegularImmutableTable<R, C, V> {
   static final ImmutableTable<Object, Object, Object> EMPTY =
       new SparseImmutableTable<>(
@@ -61,12 +64,16 @@ final class SparseImmutableTable<R, C, V> extends RegularImmutableTable<R, C, V>
       C columnKey = cell.getColumnKey();
       V value = cell.getValue();
 
-      cellRowIndices[i] = rowIndex.get(rowKey);
-      Map<C, V> thisRow = rows.get(rowKey);
+      /*
+       * These requireNonNull calls are safe because we construct the maps to hold all the provided
+       * cells.
+       */
+      cellRowIndices[i] = requireNonNull(rowIndex.get(rowKey));
+      Map<C, V> thisRow = requireNonNull(rows.get(rowKey));
       cellColumnInRowIndices[i] = thisRow.size();
       V oldValue = thisRow.put(columnKey, value);
       checkNoDuplicate(rowKey, columnKey, oldValue, value);
-      columns.get(columnKey).put(rowKey, value);
+      requireNonNull(columns.get(columnKey)).put(rowKey, value);
     }
     this.cellRowIndices = cellRowIndices;
     this.cellColumnInRowIndices = cellColumnInRowIndices;
@@ -75,14 +82,14 @@ final class SparseImmutableTable<R, C, V> extends RegularImmutableTable<R, C, V>
     for (Entry<R, Map<C, V>> row : rows.entrySet()) {
       rowBuilder.put(row.getKey(), ImmutableMap.copyOf(row.getValue()));
     }
-    this.rowMap = rowBuilder.build();
+    this.rowMap = rowBuilder.buildOrThrow();
 
     ImmutableMap.Builder<C, ImmutableMap<R, V>> columnBuilder =
         new ImmutableMap.Builder<>(columns.size());
     for (Entry<C, Map<R, V>> col : columns.entrySet()) {
       columnBuilder.put(col.getKey(), ImmutableMap.copyOf(col.getValue()));
     }
-    this.columnMap = columnBuilder.build();
+    this.columnMap = columnBuilder.buildOrThrow();
   }
 
   @Override
@@ -128,7 +135,8 @@ SerializedForm createSerializedForm() {
     int[] cellColumnIndices = new int[cellSet().size()];
     int i = 0;
     for (Cell<R, C, V> cell : cellSet()) {
-      cellColumnIndices[i++] = columnKeyToIndex.get(cell.getColumnKey());
+      // requireNonNull is safe because the cell exists in the table.
+      cellColumnIndices[i++] = requireNonNull(columnKeyToIndex.get(cell.getColumnKey()));
     }
     return SerializedForm.create(this, cellRowIndices, cellColumnIndices);
   }
diff --git a/guava/src/com/google/common/collect/StandardRowSortedTable.java b/guava/src/com/google/common/collect/StandardRowSortedTable.java
index 19a14c38533f..bea5b7bb3a86 100644
--- a/guava/src/com/google/common/collect/StandardRowSortedTable.java
+++ b/guava/src/com/google/common/collect/StandardRowSortedTable.java
@@ -26,6 +26,7 @@
 import java.util.Set;
 import java.util.SortedMap;
 import java.util.SortedSet;
+import javax.annotation.CheckForNull;
 
 /**
  * Implementation of {@code Table} whose iteration ordering across row keys is sorted by their
@@ -45,6 +46,7 @@
  * @author Jared Levy
  */
 @GwtCompatible
+@ElementTypesAreNonnullByDefault
 class StandardRowSortedTable<R, C, V> extends StandardTable<R, C, V>
     implements RowSortedTable<R, C, V> {
   /*
@@ -102,6 +104,7 @@ SortedSet<R> createKeySet() {
     }
 
     @Override
+    @CheckForNull
     public Comparator<? super R> comparator() {
       return sortedBackingMap().comparator();
     }
diff --git a/guava/src/com/google/common/collect/StandardTable.java b/guava/src/com/google/common/collect/StandardTable.java
index 6adc4dca0db8..06defb0eb847 100644
--- a/guava/src/com/google/common/collect/StandardTable.java
+++ b/guava/src/com/google/common/collect/StandardTable.java
@@ -23,6 +23,8 @@
 import static com.google.common.base.Predicates.not;
 import static com.google.common.collect.Maps.safeContainsKey;
 import static com.google.common.collect.Maps.safeGet;
+import static com.google.common.collect.NullnessCasts.uncheckedCastNullableTToT;
+import static java.util.Objects.requireNonNull;
 
 import com.google.common.annotations.GwtCompatible;
 import com.google.common.base.Function;
@@ -42,7 +44,7 @@
 import java.util.Set;
 import java.util.Spliterator;
 import java.util.Spliterators;
-import org.checkerframework.checker.nullness.qual.Nullable;
+import javax.annotation.CheckForNull;
 
 /**
  * {@link Table} implementation backed by a map that associates row keys with column key / value
@@ -64,6 +66,7 @@
  * @author Jared Levy
  */
 @GwtCompatible
+@ElementTypesAreNonnullByDefault
 class StandardTable<R, C, V> extends AbstractTable<R, C, V> implements Serializable {
   @GwtTransient final Map<R, Map<C, V>> backingMap;
   @GwtTransient final Supplier<? extends Map<C, V>> factory;
@@ -76,12 +79,12 @@ class StandardTable<R, C, V> extends AbstractTable<R, C, V> implements Serializa
   // Accessors
 
   @Override
-  public boolean contains(@Nullable Object rowKey, @Nullable Object columnKey) {
+  public boolean contains(@CheckForNull Object rowKey, @CheckForNull Object columnKey) {
     return rowKey != null && columnKey != null && super.contains(rowKey, columnKey);
   }
 
   @Override
-  public boolean containsColumn(@Nullable Object columnKey) {
+  public boolean containsColumn(@CheckForNull Object columnKey) {
     if (columnKey == null) {
       return false;
     }
@@ -94,17 +97,18 @@ public boolean containsColumn(@Nullable Object columnKey) {
   }
 
   @Override
-  public boolean containsRow(@Nullable Object rowKey) {
+  public boolean containsRow(@CheckForNull Object rowKey) {
     return rowKey != null && safeContainsKey(backingMap, rowKey);
   }
 
   @Override
-  public boolean containsValue(@Nullable Object value) {
+  public boolean containsValue(@CheckForNull Object value) {
     return value != null && super.containsValue(value);
   }
 
   @Override
-  public V get(@Nullable Object rowKey, @Nullable Object columnKey) {
+  @CheckForNull
+  public V get(@CheckForNull Object rowKey, @CheckForNull Object columnKey) {
     return (rowKey == null || columnKey == null) ? null : super.get(rowKey, columnKey);
   }
 
@@ -140,6 +144,7 @@ private Map<C, V> getOrCreate(R rowKey) {
 
   @CanIgnoreReturnValue
   @Override
+  @CheckForNull
   public V put(R rowKey, C columnKey, V value) {
     checkNotNull(rowKey);
     checkNotNull(columnKey);
@@ -149,7 +154,8 @@ public V put(R rowKey, C columnKey, V value) {
 
   @CanIgnoreReturnValue
   @Override
-  public V remove(@Nullable Object rowKey, @Nullable Object columnKey) {
+  @CheckForNull
+  public V remove(@CheckForNull Object rowKey, @CheckForNull Object columnKey) {
     if ((rowKey == null) || (columnKey == null)) {
       return null;
     }
@@ -165,7 +171,7 @@ public V remove(@Nullable Object rowKey, @Nullable Object columnKey) {
   }
 
   @CanIgnoreReturnValue
-  private Map<R, V> removeColumn(Object column) {
+  private Map<R, V> removeColumn(@CheckForNull Object column) {
     Map<R, V> output = new LinkedHashMap<>();
     Iterator<Entry<R, Map<C, V>>> iterator = backingMap.entrySet().iterator();
     while (iterator.hasNext()) {
@@ -181,12 +187,14 @@ private Map<R, V> removeColumn(Object column) {
     return output;
   }
 
-  private boolean containsMapping(Object rowKey, Object columnKey, Object value) {
+  private boolean containsMapping(
+      @CheckForNull Object rowKey, @CheckForNull Object columnKey, @CheckForNull Object value) {
     return value != null && value.equals(get(rowKey, columnKey));
   }
 
   /** Remove a row key / column key / value mapping, if present. */
-  private boolean removeMapping(Object rowKey, Object columnKey, Object value) {
+  private boolean removeMapping(
+      @CheckForNull Object rowKey, @CheckForNull Object columnKey, @CheckForNull Object value) {
     if (containsMapping(rowKey, columnKey, value)) {
       remove(rowKey, columnKey);
       return true;
@@ -234,7 +242,7 @@ Iterator<Cell<R, C, V>> cellIterator() {
 
   private class CellIterator implements Iterator<Cell<R, C, V>> {
     final Iterator<Entry<R, Map<C, V>>> rowIterator = backingMap.entrySet().iterator();
-    @Nullable Entry<R, Map<C, V>> rowEntry;
+    @CheckForNull Entry<R, Map<C, V>> rowEntry;
     Iterator<Entry<C, V>> columnIterator = Iterators.emptyModifiableIterator();
 
     @Override
@@ -248,6 +256,20 @@ public Cell<R, C, V> next() {
         rowEntry = rowIterator.next();
         columnIterator = rowEntry.getValue().entrySet().iterator();
       }
+      /*
+       * requireNonNull is safe because:
+       *
+       * - columnIterator started off pointing to an empty iterator, so we must have entered the
+       *   `if` body above at least once. Thus, if we got this far, that `if` body initialized
+       *   rowEntry at least once.
+       *
+       * - The only case in which rowEntry is cleared (during remove() below) happens only if the
+       *   caller removed every element from columnIterator. During that process, we would have had
+       *   to iterate it to exhaustion. Then we can apply the logic above about an empty
+       *   columnIterator. (This assumes no concurrent modification, but behavior under concurrent
+       *   modification is undefined, anyway.)
+       */
+      requireNonNull(rowEntry);
       Entry<C, V> columnEntry = columnIterator.next();
       return Tables.immutableCell(rowEntry.getKey(), columnEntry.getKey(), columnEntry.getValue());
     }
@@ -255,7 +277,17 @@ public Cell<R, C, V> next() {
     @Override
     public void remove() {
       columnIterator.remove();
-      if (rowEntry.getValue().isEmpty()) {
+      /*
+       * requireNonNull is safe because:
+       *
+       * - columnIterator.remove() succeeded, so it must have returned a value, so it must have been
+       * initialized by next() -- which initializes rowEntry, too.
+       *
+       * - rowEntry isn't cleared except below. If it was cleared below, then either
+       *   columnIterator.remove() would have failed above (if the user hasn't called next() since
+       *   then) or rowEntry would have been initialized by next() (as discussed above).
+       */
+      if (requireNonNull(rowEntry).getValue().isEmpty()) {
         rowIterator.remove();
         rowEntry = null;
       }
@@ -288,39 +320,43 @@ class Row extends IteratorBasedAbstractMap<C, V> {
       this.rowKey = checkNotNull(rowKey);
     }
 
-    @Nullable Map<C, V> backingRowMap;
+    @CheckForNull Map<C, V> backingRowMap;
 
-    Map<C, V> backingRowMap() {
-      return (backingRowMap == null || (backingRowMap.isEmpty() && backingMap.containsKey(rowKey)))
-          ? backingRowMap = computeBackingRowMap()
-          : backingRowMap;
+    final void updateBackingRowMapField() {
+      if (backingRowMap == null || (backingRowMap.isEmpty() && backingMap.containsKey(rowKey))) {
+        backingRowMap = computeBackingRowMap();
+      }
     }
 
+    @CheckForNull
     Map<C, V> computeBackingRowMap() {
       return backingMap.get(rowKey);
     }
 
     // Call this every time we perform a removal.
     void maintainEmptyInvariant() {
-      if (backingRowMap() != null && backingRowMap.isEmpty()) {
+      updateBackingRowMapField();
+      if (backingRowMap != null && backingRowMap.isEmpty()) {
         backingMap.remove(rowKey);
         backingRowMap = null;
       }
     }
 
     @Override
-    public boolean containsKey(Object key) {
-      Map<C, V> backingRowMap = backingRowMap();
+    public boolean containsKey(@CheckForNull Object key) {
+      updateBackingRowMapField();
       return (key != null && backingRowMap != null) && Maps.safeContainsKey(backingRowMap, key);
     }
 
     @Override
-    public V get(Object key) {
-      Map<C, V> backingRowMap = backingRowMap();
+    @CheckForNull
+    public V get(@CheckForNull Object key) {
+      updateBackingRowMapField();
       return (key != null && backingRowMap != null) ? Maps.safeGet(backingRowMap, key) : null;
     }
 
     @Override
+    @CheckForNull
     public V put(C key, V value) {
       checkNotNull(key);
       checkNotNull(value);
@@ -331,8 +367,9 @@ public V put(C key, V value) {
     }
 
     @Override
-    public V remove(Object key) {
-      Map<C, V> backingRowMap = backingRowMap();
+    @CheckForNull
+    public V remove(@CheckForNull Object key) {
+      updateBackingRowMapField();
       if (backingRowMap == null) {
         return null;
       }
@@ -343,7 +380,7 @@ public V remove(Object key) {
 
     @Override
     public void clear() {
-      Map<C, V> backingRowMap = backingRowMap();
+      updateBackingRowMapField();
       if (backingRowMap != null) {
         backingRowMap.clear();
       }
@@ -352,17 +389,17 @@ public void clear() {
 
     @Override
     public int size() {
-      Map<C, V> map = backingRowMap();
-      return (map == null) ? 0 : map.size();
+      updateBackingRowMapField();
+      return (backingRowMap == null) ? 0 : backingRowMap.size();
     }
 
     @Override
     Iterator<Entry<C, V>> entryIterator() {
-      final Map<C, V> map = backingRowMap();
-      if (map == null) {
+      updateBackingRowMapField();
+      if (backingRowMap == null) {
         return Iterators.emptyModifiableIterator();
       }
-      final Iterator<Entry<C, V>> iterator = map.entrySet().iterator();
+      final Iterator<Entry<C, V>> iterator = backingRowMap.entrySet().iterator();
       return new Iterator<Entry<C, V>>() {
         @Override
         public boolean hasNext() {
@@ -384,11 +421,11 @@ public void remove() {
 
     @Override
     Spliterator<Entry<C, V>> entrySpliterator() {
-      Map<C, V> map = backingRowMap();
-      if (map == null) {
+      updateBackingRowMapField();
+      if (backingRowMap == null) {
         return Spliterators.emptySpliterator();
       }
-      return CollectSpliterators.map(map.entrySet().spliterator(), this::wrapEntry);
+      return CollectSpliterators.map(backingRowMap.entrySet().spliterator(), this::wrapEntry);
     }
 
     Entry<C, V> wrapEntry(final Entry<C, V> entry) {
@@ -404,7 +441,7 @@ public V setValue(V value) {
         }
 
         @Override
-        public boolean equals(Object object) {
+        public boolean equals(@CheckForNull Object object) {
           // TODO(lowasser): identify why this affects GWT tests
           return standardEquals(object);
         }
@@ -430,22 +467,25 @@ private class Column extends ViewCachingAbstractMap<R, V> {
     }
 
     @Override
+    @CheckForNull
     public V put(R key, V value) {
       return StandardTable.this.put(key, columnKey, value);
     }
 
     @Override
-    public V get(Object key) {
+    @CheckForNull
+    public V get(@CheckForNull Object key) {
       return StandardTable.this.get(key, columnKey);
     }
 
     @Override
-    public boolean containsKey(Object key) {
+    public boolean containsKey(@CheckForNull Object key) {
       return StandardTable.this.contains(key, columnKey);
     }
 
     @Override
-    public V remove(Object key) {
+    @CheckForNull
+    public V remove(@CheckForNull Object key) {
       return StandardTable.this.remove(key, columnKey);
     }
 
@@ -503,7 +543,7 @@ public void clear() {
       }
 
       @Override
-      public boolean contains(Object o) {
+      public boolean contains(@CheckForNull Object o) {
         if (o instanceof Entry) {
           Entry<?, ?> entry = (Entry<?, ?>) o;
           return containsMapping(entry.getKey(), columnKey, entry.getValue());
@@ -512,7 +552,7 @@ public boolean contains(Object o) {
       }
 
       @Override
-      public boolean remove(Object obj) {
+      public boolean remove(@CheckForNull Object obj) {
         if (obj instanceof Entry) {
           Entry<?, ?> entry = (Entry<?, ?>) obj;
           return removeMapping(entry.getKey(), columnKey, entry.getValue());
@@ -530,6 +570,7 @@ private class EntrySetIterator extends AbstractIterator<Entry<R, V>> {
       final Iterator<Entry<R, Map<C, V>>> iterator = backingMap.entrySet().iterator();
 
       @Override
+      @CheckForNull
       protected Entry<R, V> computeNext() {
         while (iterator.hasNext()) {
           final Entry<R, Map<C, V>> entry = iterator.next();
@@ -548,7 +589,22 @@ public V getValue() {
 
               @Override
               public V setValue(V value) {
-                return entry.getValue().put(columnKey, checkNotNull(value));
+                /*
+                 * The cast is safe because of the containsKey check above. (Well, it's possible for
+                 * the map to change between that call and this one. But if that happens, the
+                 * behavior is undefined because of the concurrent mutation.)
+                 *
+                 * (Our prototype checker happens to be "smart" enough to understand this for the
+                 * *get* call in getValue but not for the *put* call here.)
+                 *
+                 * (Arguably we should use requireNonNull rather than uncheckedCastNullableTToT: We
+                 * know that V is a non-null type because that's the only kind of value type that
+                 * StandardTable supports. Thus, requireNonNull is safe as long as the cell is still
+                 * present. (And if it's not present, behavior is undefined.) However, that's a
+                 * behavior change relative to the old code, so it didn't seem worth risking.)
+                 */
+                return uncheckedCastNullableTToT(
+                    entry.getValue().put(columnKey, checkNotNull(value)));
               }
             }
             return new EntryImpl();
@@ -570,12 +626,12 @@ private class KeySet extends Maps.KeySet<R, V> {
       }
 
       @Override
-      public boolean contains(Object obj) {
+      public boolean contains(@CheckForNull Object obj) {
         return StandardTable.this.contains(obj, columnKey);
       }
 
       @Override
-      public boolean remove(Object obj) {
+      public boolean remove(@CheckForNull Object obj) {
         return StandardTable.this.remove(obj, columnKey) != null;
       }
 
@@ -597,7 +653,7 @@ private class Values extends Maps.Values<R, V> {
       }
 
       @Override
-      public boolean remove(Object obj) {
+      public boolean remove(@CheckForNull Object obj) {
         return obj != null && removeFromColumnIf(Maps.<V>valuePredicateOnEntries(equalTo(obj)));
       }
 
@@ -618,7 +674,7 @@ public Set<R> rowKeySet() {
     return rowMap().keySet();
   }
 
-  private transient @Nullable Set<C> columnKeySet;
+  @CheckForNull private transient Set<C> columnKeySet;
 
   /**
    * {@inheritDoc}
@@ -647,7 +703,7 @@ public int size() {
     }
 
     @Override
-    public boolean remove(Object obj) {
+    public boolean remove(@CheckForNull Object obj) {
       if (obj == null) {
         return false;
       }
@@ -702,7 +758,7 @@ public boolean retainAll(Collection<?> c) {
     }
 
     @Override
-    public boolean contains(Object obj) {
+    public boolean contains(@CheckForNull Object obj) {
       return containsColumn(obj);
     }
   }
@@ -720,6 +776,7 @@ private class ColumnKeyIterator extends AbstractIterator<C> {
     Iterator<Entry<C, V>> entryIterator = Iterators.emptyIterator();
 
     @Override
+    @CheckForNull
     protected C computeNext() {
       while (true) {
         if (entryIterator.hasNext()) {
@@ -748,7 +805,7 @@ public Collection<V> values() {
     return super.values();
   }
 
-  private transient @Nullable Map<R, Map<C, V>> rowMap;
+  @CheckForNull private transient Map<R, Map<C, V>> rowMap;
 
   @Override
   public Map<R, Map<C, V>> rowMap() {
@@ -763,19 +820,22 @@ Map<R, Map<C, V>> createRowMap() {
   @WeakOuter
   class RowMap extends ViewCachingAbstractMap<R, Map<C, V>> {
     @Override
-    public boolean containsKey(Object key) {
+    public boolean containsKey(@CheckForNull Object key) {
       return containsRow(key);
     }
 
     // performing cast only when key is in backing map and has the correct type
     @SuppressWarnings("unchecked")
     @Override
-    public Map<C, V> get(Object key) {
-      return containsRow(key) ? row((R) key) : null;
+    @CheckForNull
+    public Map<C, V> get(@CheckForNull Object key) {
+      // requireNonNull is safe because of the containsRow check.
+      return containsRow(key) ? row((R) requireNonNull(key)) : null;
     }
 
     @Override
-    public Map<C, V> remove(Object key) {
+    @CheckForNull
+    public Map<C, V> remove(@CheckForNull Object key) {
       return (key == null) ? null : backingMap.remove(key);
     }
 
@@ -804,7 +864,7 @@ public int size() {
       }
 
       @Override
-      public boolean contains(Object obj) {
+      public boolean contains(@CheckForNull Object obj) {
         if (obj instanceof Entry) {
           Entry<?, ?> entry = (Entry<?, ?>) obj;
           return entry.getKey() != null
@@ -815,7 +875,7 @@ public boolean contains(Object obj) {
       }
 
       @Override
-      public boolean remove(Object obj) {
+      public boolean remove(@CheckForNull Object obj) {
         if (obj instanceof Entry) {
           Entry<?, ?> entry = (Entry<?, ?>) obj;
           return entry.getKey() != null
@@ -827,7 +887,7 @@ public boolean remove(Object obj) {
     }
   }
 
-  private transient @Nullable ColumnMap columnMap;
+  @CheckForNull private transient ColumnMap columnMap;
 
   @Override
   public Map<C, Map<R, V>> columnMap() {
@@ -841,17 +901,20 @@ private class ColumnMap extends ViewCachingAbstractMap<C, Map<R, V>> {
     // has the correct type.
     @SuppressWarnings("unchecked")
     @Override
-    public Map<R, V> get(Object key) {
-      return containsColumn(key) ? column((C) key) : null;
+    @CheckForNull
+    public Map<R, V> get(@CheckForNull Object key) {
+      // requireNonNull is safe because of the containsColumn check.
+      return containsColumn(key) ? column((C) requireNonNull(key)) : null;
     }
 
     @Override
-    public boolean containsKey(Object key) {
+    public boolean containsKey(@CheckForNull Object key) {
       return containsColumn(key);
     }
 
     @Override
-    public Map<R, V> remove(Object key) {
+    @CheckForNull
+    public Map<R, V> remove(@CheckForNull Object key) {
       return containsColumn(key) ? removeColumn(key) : null;
     }
 
@@ -890,23 +953,24 @@ public int size() {
       }
 
       @Override
-      public boolean contains(Object obj) {
+      public boolean contains(@CheckForNull Object obj) {
         if (obj instanceof Entry) {
           Entry<?, ?> entry = (Entry<?, ?>) obj;
           if (containsColumn(entry.getKey())) {
-            // The cast to C occurs only when the key is in the map, implying
-            // that it has the correct type.
-            @SuppressWarnings("unchecked")
-            C columnKey = (C) entry.getKey();
-            return get(columnKey).equals(entry.getValue());
+            // requireNonNull is safe because of the containsColumn check.
+            return requireNonNull(get(entry.getKey())).equals(entry.getValue());
           }
         }
         return false;
       }
 
       @Override
-      public boolean remove(Object obj) {
-        if (contains(obj)) {
+      public boolean remove(@CheckForNull Object obj) {
+        /*
+         * `o instanceof Entry` is guaranteed by `contains`, but we check it here to satisfy our
+         * nullness checker.
+         */
+        if (contains(obj) && obj instanceof Entry) {
           Entry<?, ?> entry = (Entry<?, ?>) obj;
           removeColumn(entry.getKey());
           return true;
@@ -947,7 +1011,7 @@ private class ColumnMapValues extends Maps.Values<C, Map<R, V>> {
       }
 
       @Override
-      public boolean remove(Object obj) {
+      public boolean remove(@CheckForNull Object obj) {
         for (Entry<C, Map<R, V>> entry : ColumnMap.this.entrySet()) {
           if (entry.getValue().equals(obj)) {
             removeColumn(entry.getKey());
diff --git a/guava/src/com/google/common/collect/Streams.java b/guava/src/com/google/common/collect/Streams.java
index 2529b82e01d1..cd7a07c34219 100644
--- a/guava/src/com/google/common/collect/Streams.java
+++ b/guava/src/com/google/common/collect/Streams.java
@@ -17,11 +17,14 @@
 package com.google.common.collect;
 
 import static com.google.common.base.Preconditions.checkNotNull;
-import static com.google.common.base.Preconditions.checkState;
+import static com.google.common.collect.NullnessCasts.uncheckedCastNullableTToT;
+import static java.lang.Math.min;
+import static java.util.Objects.requireNonNull;
 
 import com.google.common.annotations.Beta;
 import com.google.common.annotations.GwtCompatible;
 import com.google.common.math.LongMath;
+import com.google.errorprone.annotations.InlineMe;
 import java.util.ArrayDeque;
 import java.util.Collection;
 import java.util.Deque;
@@ -45,6 +48,7 @@
 import java.util.stream.LongStream;
 import java.util.stream.Stream;
 import java.util.stream.StreamSupport;
+import javax.annotation.CheckForNull;
 import org.checkerframework.checker.nullness.qual.Nullable;
 
 /**
@@ -53,12 +57,13 @@
  * @since 21.0
  */
 @GwtCompatible
+@ElementTypesAreNonnullByDefault
 public final class Streams {
   /**
    * Returns a sequential {@link Stream} of the contents of {@code iterable}, delegating to {@link
    * Collection#stream} if possible.
    */
-  public static <T> Stream<T> stream(Iterable<T> iterable) {
+  public static <T extends @Nullable Object> Stream<T> stream(Iterable<T> iterable) {
     return (iterable instanceof Collection)
         ? ((Collection<T>) iterable).stream()
         : StreamSupport.stream(iterable.spliterator(), false);
@@ -71,7 +76,8 @@ public static <T> Stream<T> stream(Iterable<T> iterable) {
    */
   @Beta
   @Deprecated
-  public static <T> Stream<T> stream(Collection<T> collection) {
+  @InlineMe(replacement = "collection.stream()")
+  public static <T extends @Nullable Object> Stream<T> stream(Collection<T> collection) {
     return collection.stream();
   }
 
@@ -80,7 +86,7 @@ public static <T> Stream<T> stream(Collection<T> collection) {
    * {@code iterator} directly after passing it to this method.
    */
   @Beta
-  public static <T> Stream<T> stream(Iterator<T> iterator) {
+  public static <T extends @Nullable Object> Stream<T> stream(Iterator<T> iterator) {
     return StreamSupport.stream(Spliterators.spliteratorUnknownSize(iterator, 0), false);
   }
 
@@ -100,6 +106,8 @@ public static <T> Stream<T> stream(com.google.common.base.Optional<T> optional)
    * <p><b>Java 9 users:</b> use {@code optional.stream()} instead.
    */
   @Beta
+  @InlineMe(replacement = "optional.stream()")
+  @com.google.errorprone.annotations.InlineMeValidationDisabled("Java 9+ API only")
   public static <T> Stream<T> stream(java.util.Optional<T> optional) {
     return optional.isPresent() ? Stream.of(optional.get()) : Stream.empty();
   }
@@ -111,6 +119,8 @@ public static <T> Stream<T> stream(java.util.Optional<T> optional) {
    * <p><b>Java 9 users:</b> use {@code optional.stream()} instead.
    */
   @Beta
+  @InlineMe(replacement = "optional.stream()")
+  @com.google.errorprone.annotations.InlineMeValidationDisabled("Java 9+ API only")
   public static IntStream stream(OptionalInt optional) {
     return optional.isPresent() ? IntStream.of(optional.getAsInt()) : IntStream.empty();
   }
@@ -122,6 +132,8 @@ public static IntStream stream(OptionalInt optional) {
    * <p><b>Java 9 users:</b> use {@code optional.stream()} instead.
    */
   @Beta
+  @InlineMe(replacement = "optional.stream()")
+  @com.google.errorprone.annotations.InlineMeValidationDisabled("Java 9+ API only")
   public static LongStream stream(OptionalLong optional) {
     return optional.isPresent() ? LongStream.of(optional.getAsLong()) : LongStream.empty();
   }
@@ -133,6 +145,8 @@ public static LongStream stream(OptionalLong optional) {
    * <p><b>Java 9 users:</b> use {@code optional.stream()} instead.
    */
   @Beta
+  @InlineMe(replacement = "optional.stream()")
+  @com.google.errorprone.annotations.InlineMeValidationDisabled("Java 9+ API only")
   public static DoubleStream stream(OptionalDouble optional) {
     return optional.isPresent() ? DoubleStream.of(optional.getAsDouble()) : DoubleStream.empty();
   }
@@ -154,7 +168,7 @@ private static void closeAll(BaseStream<?, ?>[] toClose) {
    * @see Stream#concat(Stream, Stream)
    */
   @SafeVarargs
-  public static <T> Stream<T> concat(Stream<? extends T>... streams) {
+  public static <T extends @Nullable Object> Stream<T> concat(Stream<? extends T>... streams) {
     // TODO(lowasser): consider an implementation that can support SUBSIZED
     boolean isParallel = false;
     int characteristics = Spliterator.ORDERED | Spliterator.SIZED | Spliterator.NONNULL;
@@ -300,8 +314,9 @@ public static DoubleStream concat(DoubleStream... streams) {
    * This may harm parallel performance.
    */
   @Beta
-  public static <A, B, R> Stream<R> zip(
-      Stream<A> streamA, Stream<B> streamB, BiFunction<? super A, ? super B, R> function) {
+  public static <A extends @Nullable Object, B extends @Nullable Object, R extends @Nullable Object>
+      Stream<R> zip(
+          Stream<A> streamA, Stream<B> streamB, BiFunction<? super A, ? super B, R> function) {
     checkNotNull(streamA);
     checkNotNull(streamB);
     checkNotNull(function);
@@ -316,7 +331,7 @@ public static <A, B, R> Stream<R> zip(
     Iterator<B> itrB = Spliterators.iterator(splitrB);
     return StreamSupport.stream(
             new AbstractSpliterator<R>(
-                Math.min(splitrA.estimateSize(), splitrB.estimateSize()), characteristics) {
+                min(splitrA.estimateSize(), splitrB.estimateSize()), characteristics) {
               @Override
               public boolean tryAdvance(Consumer<? super R> action) {
                 if (itrA.hasNext() && itrB.hasNext()) {
@@ -362,7 +377,7 @@ public boolean tryAdvance(Consumer<? super R> action) {
    * @since 22.0
    */
   @Beta
-  public static <A, B> void forEachPair(
+  public static <A extends @Nullable Object, B extends @Nullable Object> void forEachPair(
       Stream<A> streamA, Stream<B> streamB, BiConsumer<? super A, ? super B> consumer) {
     checkNotNull(consumer);
 
@@ -378,11 +393,11 @@ public static <A, B> void forEachPair(
   }
 
   // Use this carefully - it doesn't implement value semantics
-  private static class TemporaryPair<A, B> {
-    final A a;
-    final B b;
+  private static class TemporaryPair<A extends @Nullable Object, B extends @Nullable Object> {
+    @ParametricNullness final A a;
+    @ParametricNullness final B b;
 
-    TemporaryPair(A a, B b) {
+    TemporaryPair(@ParametricNullness A a, @ParametricNullness B b) {
       this.a = a;
       this.b = b;
     }
@@ -395,10 +410,10 @@ private static class TemporaryPair<A, B> {
    * <pre>{@code
    * mapWithIndex(
    *     Stream.of("a", "b", "c"),
-   *     (str, index) -> str + ":" + index)
+   *     (e, index) -> index + ":" + e)
    * }</pre>
    *
-   * <p>would return {@code Stream.of("a:0", "b:1", "c:2")}.
+   * <p>would return {@code Stream.of("0:a", "1:b", "2:c")}.
    *
    * <p>The resulting stream is <a
    * href="http://gee.cs.oswego.edu/dl/html/StreamParallelGuidance.html">efficiently splittable</a>
@@ -410,8 +425,7 @@ private static class TemporaryPair<A, B> {
    * <p>The order of the resulting stream is defined if and only if the order of the original stream
    * was defined.
    */
-  @Beta
-  public static <T, R> Stream<R> mapWithIndex(
+  public static <T extends @Nullable Object, R extends @Nullable Object> Stream<R> mapWithIndex(
       Stream<T> stream, FunctionWithIndex<? super T, ? extends R> function) {
     checkNotNull(stream);
     checkNotNull(function);
@@ -439,14 +453,14 @@ public boolean tryAdvance(Consumer<? super R> action) {
           .onClose(stream::close);
     }
     class Splitr extends MapWithIndexSpliterator<Spliterator<T>, R, Splitr> implements Consumer<T> {
-      @Nullable T holder;
+      @CheckForNull T holder;
 
       Splitr(Spliterator<T> splitr, long index) {
         super(splitr, index);
       }
 
       @Override
-      public void accept(@Nullable T t) {
+      public void accept(@ParametricNullness T t) {
         this.holder = t;
       }
 
@@ -454,7 +468,8 @@ public void accept(@Nullable T t) {
       public boolean tryAdvance(Consumer<? super R> action) {
         if (fromSpliterator.tryAdvance(this)) {
           try {
-            action.accept(function.apply(holder, index++));
+            // The cast is safe because tryAdvance puts a T into `holder`.
+            action.accept(function.apply(uncheckedCastNullableTToT(holder), index++));
             return true;
           } finally {
             holder = null;
@@ -477,11 +492,11 @@ Splitr createSplit(Spliterator<T> from, long i) {
    *
    * <pre>{@code
    * mapWithIndex(
-   *     IntStream.of(0, 1, 2),
-   *     (i, index) -> i + ":" + index)
+   *     IntStream.of(10, 11, 12),
+   *     (e, index) -> index + ":" + e)
    * }</pre>
    *
-   * <p>...would return {@code Stream.of("0:0", "1:1", "2:2")}.
+   * <p>...would return {@code Stream.of("0:10", "1:11", "2:12")}.
    *
    * <p>The resulting stream is <a
    * href="http://gee.cs.oswego.edu/dl/html/StreamParallelGuidance.html">efficiently splittable</a>
@@ -493,8 +508,8 @@ Splitr createSplit(Spliterator<T> from, long i) {
    * <p>The order of the resulting stream is defined if and only if the order of the original stream
    * was defined.
    */
-  @Beta
-  public static <R> Stream<R> mapWithIndex(IntStream stream, IntFunctionWithIndex<R> function) {
+  public static <R extends @Nullable Object> Stream<R> mapWithIndex(
+      IntStream stream, IntFunctionWithIndex<R> function) {
     checkNotNull(stream);
     checkNotNull(function);
     boolean isParallel = stream.isParallel();
@@ -556,11 +571,11 @@ Splitr createSplit(Spliterator.OfInt from, long i) {
    *
    * <pre>{@code
    * mapWithIndex(
-   *     LongStream.of(0, 1, 2),
-   *     (i, index) -> i + ":" + index)
+   *     LongStream.of(10, 11, 12),
+   *     (e, index) -> index + ":" + e)
    * }</pre>
    *
-   * <p>...would return {@code Stream.of("0:0", "1:1", "2:2")}.
+   * <p>...would return {@code Stream.of("0:10", "1:11", "2:12")}.
    *
    * <p>The resulting stream is <a
    * href="http://gee.cs.oswego.edu/dl/html/StreamParallelGuidance.html">efficiently splittable</a>
@@ -572,8 +587,8 @@ Splitr createSplit(Spliterator.OfInt from, long i) {
    * <p>The order of the resulting stream is defined if and only if the order of the original stream
    * was defined.
    */
-  @Beta
-  public static <R> Stream<R> mapWithIndex(LongStream stream, LongFunctionWithIndex<R> function) {
+  public static <R extends @Nullable Object> Stream<R> mapWithIndex(
+      LongStream stream, LongFunctionWithIndex<R> function) {
     checkNotNull(stream);
     checkNotNull(function);
     boolean isParallel = stream.isParallel();
@@ -635,11 +650,11 @@ Splitr createSplit(Spliterator.OfLong from, long i) {
    *
    * <pre>{@code
    * mapWithIndex(
-   *     DoubleStream.of(0, 1, 2),
-   *     (x, index) -> x + ":" + index)
+   *     DoubleStream.of(0.0, 1.0, 2.0)
+   *     (e, index) -> index + ":" + e)
    * }</pre>
    *
-   * <p>...would return {@code Stream.of("0.0:0", "1.0:1", "2.0:2")}.
+   * <p>...would return {@code Stream.of("0:0.0", "1:1.0", "2:2.0")}.
    *
    * <p>The resulting stream is <a
    * href="http://gee.cs.oswego.edu/dl/html/StreamParallelGuidance.html">efficiently splittable</a>
@@ -651,8 +666,7 @@ Splitr createSplit(Spliterator.OfLong from, long i) {
    * <p>The order of the resulting stream is defined if and only if the order of the original stream
    * was defined.
    */
-  @Beta
-  public static <R> Stream<R> mapWithIndex(
+  public static <R extends @Nullable Object> Stream<R> mapWithIndex(
       DoubleStream stream, DoubleFunctionWithIndex<R> function) {
     checkNotNull(stream);
     checkNotNull(function);
@@ -717,14 +731,16 @@ Splitr createSplit(Spliterator.OfDouble from, long i) {
    *
    * @since 21.0
    */
-  @Beta
-  public interface FunctionWithIndex<T, R> {
+  public interface FunctionWithIndex<T extends @Nullable Object, R extends @Nullable Object> {
     /** Applies this function to the given argument and its index within a stream. */
-    R apply(T from, long index);
+    @ParametricNullness
+    R apply(@ParametricNullness T from, long index);
   }
 
   private abstract static class MapWithIndexSpliterator<
-          F extends Spliterator<?>, R, S extends MapWithIndexSpliterator<F, R, S>>
+          F extends Spliterator<?>,
+          R extends @Nullable Object,
+          S extends MapWithIndexSpliterator<F, R, S>>
       implements Spliterator<R> {
     final F fromSpliterator;
     long index;
@@ -737,12 +753,14 @@ private abstract static class MapWithIndexSpliterator<
     abstract S createSplit(F from, long i);
 
     @Override
+    @CheckForNull
     public S trySplit() {
-      @SuppressWarnings("unchecked")
-      F split = (F) fromSpliterator.trySplit();
-      if (split == null) {
+      Spliterator<?> splitOrNull = fromSpliterator.trySplit();
+      if (splitOrNull == null) {
         return null;
       }
+      @SuppressWarnings("unchecked")
+      F split = (F) splitOrNull;
       S result = createSplit(split, index);
       this.index += split.getExactSizeIfKnown();
       return result;
@@ -768,9 +786,9 @@ public int characteristics() {
    *
    * @since 21.0
    */
-  @Beta
-  public interface IntFunctionWithIndex<R> {
+  public interface IntFunctionWithIndex<R extends @Nullable Object> {
     /** Applies this function to the given argument and its index within a stream. */
+    @ParametricNullness
     R apply(int from, long index);
   }
 
@@ -782,9 +800,9 @@ public interface IntFunctionWithIndex<R> {
    *
    * @since 21.0
    */
-  @Beta
-  public interface LongFunctionWithIndex<R> {
+  public interface LongFunctionWithIndex<R extends @Nullable Object> {
     /** Applies this function to the given argument and its index within a stream. */
+    @ParametricNullness
     R apply(long from, long index);
   }
 
@@ -796,9 +814,9 @@ public interface LongFunctionWithIndex<R> {
    *
    * @since 21.0
    */
-  @Beta
-  public interface DoubleFunctionWithIndex<R> {
+  public interface DoubleFunctionWithIndex<R extends @Nullable Object> {
     /** Applies this function to the given argument and its index within a stream. */
+    @ParametricNullness
     R apply(double from, long index);
   }
 
@@ -817,20 +835,33 @@ public interface DoubleFunctionWithIndex<R> {
    * @see Stream#findFirst()
    * @throws NullPointerException if the last element of the stream is null
    */
-  @Beta
+  /*
+   * By declaring <T> instead of <T extends @Nullable Object>, we declare this method as requiring a
+   * stream whose elements are non-null. However, the method goes out of its way to still handle
+   * nulls in the stream. This means that the method can safely be used with a stream that contains
+   * nulls as long as the *last* element is *not* null.
+   *
+   * (To "go out of its way," the method tracks a `set` bit so that it can distinguish "the final
+   * split has a last element of null, so throw NPE" from "the final split was empty, so look for an
+   * element in the prior one.")
+   */
   public static <T> java.util.Optional<T> findLast(Stream<T> stream) {
     class OptionalState {
       boolean set = false;
-      T value = null;
+      @CheckForNull T value = null;
 
-      void set(@Nullable T value) {
+      void set(T value) {
         this.set = true;
         this.value = value;
       }
 
       T get() {
-        checkState(set);
-        return value;
+        /*
+         * requireNonNull is safe because we call get() only if we've previously called set().
+         *
+         * (For further discussion of nullness, see the comment above the method.)
+         */
+        return requireNonNull(value);
       }
     }
     OptionalState state = new OptionalState();
@@ -892,7 +923,6 @@ T get() {
    * @see IntStream#findFirst()
    * @throws NullPointerException if the last element of the stream is null
    */
-  @Beta
   public static OptionalInt findLast(IntStream stream) {
     // findLast(Stream) does some allocation, so we might as well box some more
     java.util.Optional<Integer> boxedLast = findLast(stream.boxed());
@@ -911,7 +941,6 @@ public static OptionalInt findLast(IntStream stream) {
    * @see LongStream#findFirst()
    * @throws NullPointerException if the last element of the stream is null
    */
-  @Beta
   public static OptionalLong findLast(LongStream stream) {
     // findLast(Stream) does some allocation, so we might as well box some more
     java.util.Optional<Long> boxedLast = findLast(stream.boxed());
@@ -930,7 +959,6 @@ public static OptionalLong findLast(LongStream stream) {
    * @see DoubleStream#findFirst()
    * @throws NullPointerException if the last element of the stream is null
    */
-  @Beta
   public static OptionalDouble findLast(DoubleStream stream) {
     // findLast(Stream) does some allocation, so we might as well box some more
     java.util.Optional<Double> boxedLast = findLast(stream.boxed());
diff --git a/guava/src/com/google/common/collect/Synchronized.java b/guava/src/com/google/common/collect/Synchronized.java
index 60eaf2045ba0..1089c9e99ad2 100644
--- a/guava/src/com/google/common/collect/Synchronized.java
+++ b/guava/src/com/google/common/collect/Synchronized.java
@@ -32,7 +32,6 @@
 import java.util.List;
 import java.util.ListIterator;
 import java.util.Map;
-import java.util.Map.Entry;
 import java.util.NavigableMap;
 import java.util.NavigableSet;
 import java.util.Queue;
@@ -48,6 +47,7 @@
 import java.util.function.Predicate;
 import java.util.function.UnaryOperator;
 import java.util.stream.Stream;
+import javax.annotation.CheckForNull;
 import org.checkerframework.checker.nullness.qual.Nullable;
 import org.checkerframework.dataflow.qual.Pure;
 import org.checkerframework.dataflow.qual.SideEffectFree;
@@ -67,6 +67,16 @@
  */
 @AnnotatedFor({"nullness"})
 @GwtCompatible(emulated = true)
+@ElementTypesAreNonnullByDefault
+/*
+ * I have decided not to bother adding @ParametricNullness annotations in this class. Adding them is
+ * a lot of busy work, and the annotation matters only when the APIs to be annotated are visible to
+ * Kotlin code. In this class, nothing is publicly visible (nor exposed indirectly through a
+ * publicly visible subclass), and I doubt any of our current or future Kotlin extensions for the
+ * package will refer to the class. Plus, @ParametricNullness is only a temporary workaround,
+ * anyway, so we just need to get by without the annotations here until Kotlin better understands
+ * our other nullness annotations.
+ */
 final class Synchronized {
   private Synchronized() {}
 
@@ -74,7 +84,7 @@ static class SynchronizedObject implements Serializable {
     final Object delegate;
     final Object mutex;
 
-    SynchronizedObject(Object delegate, @Nullable Object mutex) {
+    SynchronizedObject(Object delegate, @CheckForNull Object mutex) {
       this.delegate = checkNotNull(delegate);
       this.mutex = (mutex == null) ? this : mutex;
     }
@@ -109,13 +119,15 @@ private void writeObject(ObjectOutputStream stream) throws IOException {
     private static final long serialVersionUID = 0;
   }
 
-  private static <E> Collection<E> collection(Collection<E> collection, @Nullable Object mutex) {
+  private static <E extends @Nullable Object> Collection<E> collection(
+      Collection<E> collection, @CheckForNull Object mutex) {
     return new SynchronizedCollection<E>(collection, mutex);
   }
 
   @VisibleForTesting
-  static class SynchronizedCollection<E> extends SynchronizedObject implements Collection<E> {
-    private SynchronizedCollection(Collection<E> delegate, @Nullable Object mutex) {
+  static class SynchronizedCollection<E extends @Nullable Object> extends SynchronizedObject
+      implements Collection<E> {
+    private SynchronizedCollection(Collection<E> delegate, @CheckForNull Object mutex) {
       super(delegate, mutex);
     }
 
@@ -148,7 +160,7 @@ public void clear() {
 
     @Pure
     @Override
-    public boolean contains(@Nullable Object o) {
+    public boolean contains(@CheckForNull Object o) {
       synchronized (mutex) {
         return delegate().contains(o);
       }
@@ -204,7 +216,7 @@ public void forEach(Consumer<? super E> action) {
     }
 
     @Override
-    public boolean remove(@Nullable Object o) {
+    public boolean remove(@CheckForNull Object o) {
       synchronized (mutex) {
         return delegate().remove(o);
       }
@@ -247,7 +259,8 @@ public int size() {
     }
 
     @Override
-    public <T> T[] toArray(T[] a) {
+    @SuppressWarnings("nullness") // b/192354773 in our checker affects toArray declarations
+    public <T extends @Nullable Object> T[] toArray(T[] a) {
       synchronized (mutex) {
         return delegate().toArray(a);
       }
@@ -257,13 +270,14 @@ public <T> T[] toArray(T[] a) {
   }
 
   @VisibleForTesting
-  static <E> Set<E> set(Set<E> set, @Nullable Object mutex) {
+  static <E extends @Nullable Object> Set<E> set(Set<E> set, @CheckForNull Object mutex) {
     return new SynchronizedSet<E>(set, mutex);
   }
 
-  static class SynchronizedSet<E> extends SynchronizedCollection<E> implements Set<E> {
+  static class SynchronizedSet<E extends @Nullable Object> extends SynchronizedCollection<E>
+      implements Set<E> {
 
-    SynchronizedSet(Set<E> delegate, @Nullable Object mutex) {
+    SynchronizedSet(Set<E> delegate, @CheckForNull Object mutex) {
       super(delegate, mutex);
     }
 
@@ -274,7 +288,7 @@ Set<E> delegate() {
 
     @Pure
     @Override
-    public boolean equals(@Nullable Object o) {
+    public boolean equals(@CheckForNull Object o) {
       if (o == this) {
         return true;
       }
@@ -294,12 +308,14 @@ public int hashCode() {
     private static final long serialVersionUID = 0;
   }
 
-  private static <E> SortedSet<E> sortedSet(SortedSet<E> set, @Nullable Object mutex) {
+  private static <E extends @Nullable Object> SortedSet<E> sortedSet(
+      SortedSet<E> set, @CheckForNull Object mutex) {
     return new SynchronizedSortedSet<E>(set, mutex);
   }
 
-  static class SynchronizedSortedSet<E> extends SynchronizedSet<E> implements SortedSet<E> {
-    SynchronizedSortedSet(SortedSet<E> delegate, @Nullable Object mutex) {
+  static class SynchronizedSortedSet<E extends @Nullable Object> extends SynchronizedSet<E>
+      implements SortedSet<E> {
+    SynchronizedSortedSet(SortedSet<E> delegate, @CheckForNull Object mutex) {
       super(delegate, mutex);
     }
 
@@ -310,6 +326,7 @@ SortedSet<E> delegate() {
 
     @SideEffectFree
     @Override
+    @CheckForNull
     public Comparator<? super E> comparator() {
       synchronized (mutex) {
         return delegate().comparator();
@@ -359,14 +376,16 @@ public E last() {
     private static final long serialVersionUID = 0;
   }
 
-  private static <E> List<E> list(List<E> list, @Nullable Object mutex) {
+  private static <E extends @Nullable Object> List<E> list(
+      List<E> list, @CheckForNull Object mutex) {
     return (list instanceof RandomAccess)
         ? new SynchronizedRandomAccessList<E>(list, mutex)
         : new SynchronizedList<E>(list, mutex);
   }
 
-  private static class SynchronizedList<E> extends SynchronizedCollection<E> implements List<E> {
-    SynchronizedList(List<E> delegate, @Nullable Object mutex) {
+  private static class SynchronizedList<E extends @Nullable Object>
+      extends SynchronizedCollection<E> implements List<E> {
+    SynchronizedList(List<E> delegate, @CheckForNull Object mutex) {
       super(delegate, mutex);
     }
 
@@ -398,7 +417,7 @@ public E get(int index) {
 
     @Pure
     @Override
-    public int indexOf(@Nullable Object o) {
+    public int indexOf(@CheckForNull Object o) {
       synchronized (mutex) {
         return delegate().indexOf(o);
       }
@@ -406,7 +425,7 @@ public int indexOf(@Nullable Object o) {
 
     @Pure
     @Override
-    public int lastIndexOf(@Nullable Object o) {
+    public int lastIndexOf(@CheckForNull Object o) {
       synchronized (mutex) {
         return delegate().lastIndexOf(o);
       }
@@ -460,7 +479,7 @@ public List<E> subList(int fromIndex, int toIndex) {
 
     @Pure
     @Override
-    public boolean equals(@Nullable Object o) {
+    public boolean equals(@CheckForNull Object o) {
       if (o == this) {
         return true;
       }
@@ -480,28 +499,29 @@ public int hashCode() {
     private static final long serialVersionUID = 0;
   }
 
-  private static class SynchronizedRandomAccessList<E> extends SynchronizedList<E>
-      implements RandomAccess {
-    SynchronizedRandomAccessList(List<E> list, @Nullable Object mutex) {
+  private static class SynchronizedRandomAccessList<E extends @Nullable Object>
+      extends SynchronizedList<E> implements RandomAccess {
+    SynchronizedRandomAccessList(List<E> list, @CheckForNull Object mutex) {
       super(list, mutex);
     }
 
     private static final long serialVersionUID = 0;
   }
 
-  static <E> Multiset<E> multiset(Multiset<E> multiset, @Nullable Object mutex) {
+  static <E extends @Nullable Object> Multiset<E> multiset(
+      Multiset<E> multiset, @CheckForNull Object mutex) {
     if (multiset instanceof SynchronizedMultiset || multiset instanceof ImmutableMultiset) {
       return multiset;
     }
     return new SynchronizedMultiset<E>(multiset, mutex);
   }
 
-  private static class SynchronizedMultiset<E> extends SynchronizedCollection<E>
-      implements Multiset<E> {
-    transient @Nullable Set<E> elementSet;
-    transient @Nullable Set<Entry<E>> entrySet;
+  private static class SynchronizedMultiset<E extends @Nullable Object>
+      extends SynchronizedCollection<E> implements Multiset<E> {
+    @CheckForNull transient Set<E> elementSet;
+    @CheckForNull transient Set<Multiset.Entry<E>> entrySet;
 
-    SynchronizedMultiset(Multiset<E> delegate, @Nullable Object mutex) {
+    SynchronizedMultiset(Multiset<E> delegate, @CheckForNull Object mutex) {
       super(delegate, mutex);
     }
 
@@ -511,7 +531,7 @@ Multiset<E> delegate() {
     }
 
     @Override
-    public int count(@Nullable Object o) {
+    public int count(@CheckForNull Object o) {
       synchronized (mutex) {
         return delegate().count(o);
       }
@@ -525,7 +545,7 @@ public int add(E e, int n) {
     }
 
     @Override
-    public int remove(@Nullable Object o, int n) {
+    public int remove(@CheckForNull Object o, int n) {
       synchronized (mutex) {
         return delegate().remove(o, n);
       }
@@ -558,7 +578,7 @@ public Set<E> elementSet() {
 
     @SideEffectFree
     @Override
-    public Set<Entry<E>> entrySet() {
+    public Set<Multiset.Entry<E>> entrySet() {
       synchronized (mutex) {
         if (entrySet == null) {
           entrySet = typePreservingSet(delegate().entrySet(), mutex);
@@ -569,7 +589,7 @@ public Set<Entry<E>> entrySet() {
 
     @Pure
     @Override
-    public boolean equals(@Nullable Object o) {
+    public boolean equals(@CheckForNull Object o) {
       if (o == this) {
         return true;
       }
@@ -589,20 +609,21 @@ public int hashCode() {
     private static final long serialVersionUID = 0;
   }
 
-  static <K, V> Multimap<K, V> multimap(Multimap<K, V> multimap, @Nullable Object mutex) {
+  static <K extends @Nullable Object, V extends @Nullable Object> Multimap<K, V> multimap(
+      Multimap<K, V> multimap, @CheckForNull Object mutex) {
     if (multimap instanceof SynchronizedMultimap || multimap instanceof BaseImmutableMultimap) {
       return multimap;
     }
     return new SynchronizedMultimap<>(multimap, mutex);
   }
 
-  private static class SynchronizedMultimap<K, V> extends SynchronizedObject
-      implements Multimap<K, V> {
-    transient @Nullable Set<K> keySet;
-    transient @Nullable Collection<V> valuesCollection;
-    transient @Nullable Collection<Entry<K, V>> entries;
-    transient @Nullable Map<K, Collection<V>> asMap;
-    transient @Nullable Multiset<K> keys;
+  private static class SynchronizedMultimap<K extends @Nullable Object, V extends @Nullable Object>
+      extends SynchronizedObject implements Multimap<K, V> {
+    @CheckForNull transient Set<K> keySet;
+    @CheckForNull transient Collection<V> valuesCollection;
+    @CheckForNull transient Collection<Map.Entry<K, V>> entries;
+    @CheckForNull transient Map<K, Collection<V>> asMap;
+    @CheckForNull transient Multiset<K> keys;
 
     @SuppressWarnings("unchecked")
     @Override
@@ -610,7 +631,7 @@ Multimap<K, V> delegate() {
       return (Multimap<K, V>) super.delegate();
     }
 
-    SynchronizedMultimap(Multimap<K, V> delegate, @Nullable Object mutex) {
+    SynchronizedMultimap(Multimap<K, V> delegate, @CheckForNull Object mutex) {
       super(delegate, mutex);
     }
 
@@ -632,7 +653,7 @@ public boolean isEmpty() {
 
     @Pure
     @Override
-    public boolean containsKey(@Nullable Object key) {
+    public boolean containsKey(@CheckForNull Object key) {
       synchronized (mutex) {
         return delegate().containsKey(key);
       }
@@ -640,7 +661,7 @@ public boolean containsKey(@Nullable Object key) {
 
     @Pure
     @Override
-    public boolean containsValue(@Nullable Object value) {
+    public boolean containsValue(@CheckForNull Object value) {
       synchronized (mutex) {
         return delegate().containsValue(value);
       }
@@ -648,7 +669,7 @@ public boolean containsValue(@Nullable Object value) {
 
     @Pure
     @Override
-    public boolean containsEntry(@Nullable Object key, @Nullable Object value) {
+    public boolean containsEntry(@CheckForNull Object key, @CheckForNull Object value) {
       synchronized (mutex) {
         return delegate().containsEntry(key, value);
       }
@@ -690,14 +711,14 @@ public Collection<V> replaceValues(K key, Iterable<? extends V> values) {
     }
 
     @Override
-    public boolean remove(@Nullable Object key, @Nullable Object value) {
+    public boolean remove(@CheckForNull Object key, @CheckForNull Object value) {
       synchronized (mutex) {
         return delegate().remove(key, value);
       }
     }
 
     @Override
-    public Collection<V> removeAll(@Nullable Object key) {
+    public Collection<V> removeAll(@CheckForNull Object key) {
       synchronized (mutex) {
         return delegate().removeAll(key); // copy not synchronized
       }
@@ -734,7 +755,7 @@ public Collection<V> values() {
 
     @SideEffectFree
     @Override
-    public Collection<Entry<K, V>> entries() {
+    public Collection<Map.Entry<K, V>> entries() {
       synchronized (mutex) {
         if (entries == null) {
           entries = typePreservingCollection(delegate().entries(), mutex);
@@ -772,7 +793,7 @@ public Multiset<K> keys() {
 
     @Pure
     @Override
-    public boolean equals(@Nullable Object o) {
+    public boolean equals(@CheckForNull Object o) {
       if (o == this) {
         return true;
       }
@@ -792,17 +813,18 @@ public int hashCode() {
     private static final long serialVersionUID = 0;
   }
 
-  static <K, V> ListMultimap<K, V> listMultimap(
-      ListMultimap<K, V> multimap, @Nullable Object mutex) {
+  static <K extends @Nullable Object, V extends @Nullable Object> ListMultimap<K, V> listMultimap(
+      ListMultimap<K, V> multimap, @CheckForNull Object mutex) {
     if (multimap instanceof SynchronizedListMultimap || multimap instanceof BaseImmutableMultimap) {
       return multimap;
     }
     return new SynchronizedListMultimap<>(multimap, mutex);
   }
 
-  private static class SynchronizedListMultimap<K, V> extends SynchronizedMultimap<K, V>
-      implements ListMultimap<K, V> {
-    SynchronizedListMultimap(ListMultimap<K, V> delegate, @Nullable Object mutex) {
+  private static class SynchronizedListMultimap<
+          K extends @Nullable Object, V extends @Nullable Object>
+      extends SynchronizedMultimap<K, V> implements ListMultimap<K, V> {
+    SynchronizedListMultimap(ListMultimap<K, V> delegate, @CheckForNull Object mutex) {
       super(delegate, mutex);
     }
 
@@ -819,7 +841,7 @@ public List<V> get(K key) {
     }
 
     @Override
-    public List<V> removeAll(@Nullable Object key) {
+    public List<V> removeAll(@CheckForNull Object key) {
       synchronized (mutex) {
         return delegate().removeAll(key); // copy not synchronized
       }
@@ -835,18 +857,20 @@ public List<V> replaceValues(K key, Iterable<? extends V> values) {
     private static final long serialVersionUID = 0;
   }
 
-  static <K, V> SetMultimap<K, V> setMultimap(SetMultimap<K, V> multimap, @Nullable Object mutex) {
+  static <K extends @Nullable Object, V extends @Nullable Object> SetMultimap<K, V> setMultimap(
+      SetMultimap<K, V> multimap, @CheckForNull Object mutex) {
     if (multimap instanceof SynchronizedSetMultimap || multimap instanceof BaseImmutableMultimap) {
       return multimap;
     }
     return new SynchronizedSetMultimap<>(multimap, mutex);
   }
 
-  private static class SynchronizedSetMultimap<K, V> extends SynchronizedMultimap<K, V>
-      implements SetMultimap<K, V> {
-    transient @Nullable Set<Entry<K, V>> entrySet;
+  private static class SynchronizedSetMultimap<
+          K extends @Nullable Object, V extends @Nullable Object>
+      extends SynchronizedMultimap<K, V> implements SetMultimap<K, V> {
+    @CheckForNull transient Set<Map.Entry<K, V>> entrySet;
 
-    SynchronizedSetMultimap(SetMultimap<K, V> delegate, @Nullable Object mutex) {
+    SynchronizedSetMultimap(SetMultimap<K, V> delegate, @CheckForNull Object mutex) {
       super(delegate, mutex);
     }
 
@@ -863,7 +887,7 @@ public Set<V> get(K key) {
     }
 
     @Override
-    public Set<V> removeAll(@Nullable Object key) {
+    public Set<V> removeAll(@CheckForNull Object key) {
       synchronized (mutex) {
         return delegate().removeAll(key); // copy not synchronized
       }
@@ -878,7 +902,7 @@ public Set<V> replaceValues(K key, Iterable<? extends V> values) {
 
     @SideEffectFree
     @Override
-    public Set<Entry<K, V>> entries() {
+    public Set<Map.Entry<K, V>> entries() {
       synchronized (mutex) {
         if (entrySet == null) {
           entrySet = set(delegate().entries(), mutex);
@@ -890,17 +914,19 @@ public Set<Entry<K, V>> entries() {
     private static final long serialVersionUID = 0;
   }
 
-  static <K, V> SortedSetMultimap<K, V> sortedSetMultimap(
-      SortedSetMultimap<K, V> multimap, @Nullable Object mutex) {
+  static <K extends @Nullable Object, V extends @Nullable Object>
+      SortedSetMultimap<K, V> sortedSetMultimap(
+          SortedSetMultimap<K, V> multimap, @CheckForNull Object mutex) {
     if (multimap instanceof SynchronizedSortedSetMultimap) {
       return multimap;
     }
     return new SynchronizedSortedSetMultimap<>(multimap, mutex);
   }
 
-  private static class SynchronizedSortedSetMultimap<K, V> extends SynchronizedSetMultimap<K, V>
-      implements SortedSetMultimap<K, V> {
-    SynchronizedSortedSetMultimap(SortedSetMultimap<K, V> delegate, @Nullable Object mutex) {
+  private static class SynchronizedSortedSetMultimap<
+          K extends @Nullable Object, V extends @Nullable Object>
+      extends SynchronizedSetMultimap<K, V> implements SortedSetMultimap<K, V> {
+    SynchronizedSortedSetMultimap(SortedSetMultimap<K, V> delegate, @CheckForNull Object mutex) {
       super(delegate, mutex);
     }
 
@@ -917,7 +943,7 @@ public SortedSet<V> get(K key) {
     }
 
     @Override
-    public SortedSet<V> removeAll(@Nullable Object key) {
+    public SortedSet<V> removeAll(@CheckForNull Object key) {
       synchronized (mutex) {
         return delegate().removeAll(key); // copy not synchronized
       }
@@ -931,7 +957,8 @@ public SortedSet<V> replaceValues(K key, Iterable<? extends V> values) {
     }
 
     @Override
-    public @Nullable Comparator<? super V> valueComparator() {
+    @CheckForNull
+    public Comparator<? super V> valueComparator() {
       synchronized (mutex) {
         return delegate().valueComparator();
       }
@@ -940,8 +967,8 @@ public SortedSet<V> replaceValues(K key, Iterable<? extends V> values) {
     private static final long serialVersionUID = 0;
   }
 
-  private static <E> Collection<E> typePreservingCollection(
-      Collection<E> collection, @Nullable Object mutex) {
+  private static <E extends @Nullable Object> Collection<E> typePreservingCollection(
+      Collection<E> collection, @CheckForNull Object mutex) {
     if (collection instanceof SortedSet) {
       return sortedSet((SortedSet<E>) collection, mutex);
     }
@@ -954,7 +981,8 @@ private static <E> Collection<E> typePreservingCollection(
     return collection(collection, mutex);
   }
 
-  private static <E> Set<E> typePreservingSet(Set<E> set, @Nullable Object mutex) {
+  private static <E extends @Nullable Object> Set<E> typePreservingSet(
+      Set<E> set, @CheckForNull Object mutex) {
     if (set instanceof SortedSet) {
       return sortedSet((SortedSet<E>) set, mutex);
     } else {
@@ -962,22 +990,24 @@ private static <E> Set<E> typePreservingSet(Set<E> set, @Nullable Object mutex)
     }
   }
 
-  private static class SynchronizedAsMapEntries<K, V>
-      extends SynchronizedSet<Entry<K, Collection<V>>> {
-    SynchronizedAsMapEntries(Set<Entry<K, Collection<V>>> delegate, @Nullable Object mutex) {
+  private static class SynchronizedAsMapEntries<
+          K extends @Nullable Object, V extends @Nullable Object>
+      extends SynchronizedSet<Map.Entry<K, Collection<V>>> {
+    SynchronizedAsMapEntries(
+        Set<Map.Entry<K, Collection<V>>> delegate, @CheckForNull Object mutex) {
       super(delegate, mutex);
     }
 
     @Override
-    public Iterator<Entry<K, Collection<V>>> iterator() {
+    public Iterator<Map.Entry<K, Collection<V>>> iterator() {
       // Must be manually synchronized.
-      return new TransformedIterator<Entry<K, Collection<V>>, Entry<K, Collection<V>>>(
+      return new TransformedIterator<Map.Entry<K, Collection<V>>, Map.Entry<K, Collection<V>>>(
           super.iterator()) {
         @Override
-        Entry<K, Collection<V>> transform(final Entry<K, Collection<V>> entry) {
+        Map.Entry<K, Collection<V>> transform(final Map.Entry<K, Collection<V>> entry) {
           return new ForwardingMapEntry<K, Collection<V>>() {
             @Override
-            protected Entry<K, Collection<V>> delegate() {
+            protected Map.Entry<K, Collection<V>> delegate() {
               return entry;
             }
 
@@ -995,12 +1025,20 @@ public Collection<V> getValue() {
     @Override
     public @Nullable Object[] toArray() {
       synchronized (mutex) {
-        return ObjectArrays.toArrayImpl(delegate());
+        /*
+         * toArrayImpl returns `@Nullable Object[]` rather than `Object[]` but only because it can
+         * be used with collections that may contain null. This collection never contains nulls, so
+         * we can treat it as a plain `Object[]`.
+         */
+        @SuppressWarnings("nullness")
+        Object[] result = (Object[]) ObjectArrays.toArrayImpl(delegate());
+        return result;
       }
     }
 
     @Override
-    public <T> T[] toArray(T[] array) {
+    @SuppressWarnings("nullness") // b/192354773 in our checker affects toArray declarations
+    public <T extends @Nullable Object> T[] toArray(T[] array) {
       synchronized (mutex) {
         return ObjectArrays.toArrayImpl(delegate(), array);
       }
@@ -1008,7 +1046,7 @@ public <T> T[] toArray(T[] array) {
 
     @Pure
     @Override
-    public boolean contains(@Nullable Object o) {
+    public boolean contains(@CheckForNull Object o) {
       synchronized (mutex) {
         return Maps.containsEntryImpl(delegate(), o);
       }
@@ -1024,7 +1062,7 @@ public boolean containsAll(Collection<?> c) {
 
     @Pure
     @Override
-    public boolean equals(@Nullable Object o) {
+    public boolean equals(@CheckForNull Object o) {
       if (o == this) {
         return true;
       }
@@ -1034,7 +1072,7 @@ public boolean equals(@Nullable Object o) {
     }
 
     @Override
-    public boolean remove(@Nullable Object o) {
+    public boolean remove(@CheckForNull Object o) {
       synchronized (mutex) {
         return Maps.removeEntryImpl(delegate(), o);
       }
@@ -1058,16 +1096,18 @@ public boolean retainAll(Collection<?> c) {
   }
 
   @VisibleForTesting
-  static <K, V> Map<K, V> map(Map<K, V> map, @Nullable Object mutex) {
+  static <K extends @Nullable Object, V extends @Nullable Object> Map<K, V> map(
+      Map<K, V> map, @CheckForNull Object mutex) {
     return new SynchronizedMap<>(map, mutex);
   }
 
-  private static class SynchronizedMap<K, V> extends SynchronizedObject implements Map<K, V> {
-    transient @Nullable Set<K> keySet;
-    transient @Nullable Collection<V> values;
-    transient @Nullable Set<Entry<K, V>> entrySet;
+  private static class SynchronizedMap<K extends @Nullable Object, V extends @Nullable Object>
+      extends SynchronizedObject implements Map<K, V> {
+    @CheckForNull transient Set<K> keySet;
+    @CheckForNull transient Collection<V> values;
+    @CheckForNull transient Set<Map.Entry<K, V>> entrySet;
 
-    SynchronizedMap(Map<K, V> delegate, @Nullable Object mutex) {
+    SynchronizedMap(Map<K, V> delegate, @CheckForNull Object mutex) {
       super(delegate, mutex);
     }
 
@@ -1086,7 +1126,7 @@ public void clear() {
 
     @Pure
     @Override
-    public boolean containsKey(@Nullable Object key) {
+    public boolean containsKey(@CheckForNull Object key) {
       synchronized (mutex) {
         return delegate().containsKey(key);
       }
@@ -1094,7 +1134,7 @@ public boolean containsKey(@Nullable Object key) {
 
     @Pure
     @Override
-    public boolean containsValue(@Nullable Object value) {
+    public boolean containsValue(@CheckForNull Object value) {
       synchronized (mutex) {
         return delegate().containsValue(value);
       }
@@ -1102,7 +1142,7 @@ public boolean containsValue(@Nullable Object value) {
 
     @SideEffectFree
     @Override
-    public Set<Entry<K, V>> entrySet() {
+    public Set<Map.Entry<K, V>> entrySet() {
       synchronized (mutex) {
         if (entrySet == null) {
           entrySet = set(delegate().entrySet(), mutex);
@@ -1119,7 +1159,8 @@ public void forEach(BiConsumer<? super K, ? super V> action) {
     }
 
     @Override
-    public @Nullable V get(@Nullable Object key) {
+    @CheckForNull
+    public V get(@CheckForNull Object key) {
       synchronized (mutex) {
         return delegate().get(key);
       }
@@ -1127,7 +1168,8 @@ public void forEach(BiConsumer<? super K, ? super V> action) {
 
     @Pure
     @Override
-    public V getOrDefault(Object key, V defaultValue) {
+    @CheckForNull
+    public V getOrDefault(@CheckForNull Object key, @CheckForNull V defaultValue) {
       synchronized (mutex) {
         return delegate().getOrDefault(key, defaultValue);
       }
@@ -1152,6 +1194,7 @@ public Set<K> keySet() {
     }
 
     @Override
+    @CheckForNull
     public V put(K key, V value) {
       synchronized (mutex) {
         return delegate().put(key, value);
@@ -1159,6 +1202,7 @@ public V put(K key, V value) {
     }
 
     @Override
+    @CheckForNull
     public V putIfAbsent(K key, V value) {
       synchronized (mutex) {
         return delegate().putIfAbsent(key, value);
@@ -1173,6 +1217,7 @@ public boolean replace(K key, V oldValue, V newValue) {
     }
 
     @Override
+    @CheckForNull
     public V replace(K key, V value) {
       synchronized (mutex) {
         return delegate().replace(key, value);
@@ -1195,7 +1240,8 @@ public V computeIfPresent(
     }
 
     @Override
-    public V compute(K key, BiFunction<? super K, ? super V, ? extends V> remappingFunction) {
+    public V compute(
+        K key, BiFunction<? super K, ? super @Nullable V, ? extends V> remappingFunction) {
       synchronized (mutex) {
         return delegate().compute(key, remappingFunction);
       }
@@ -1224,7 +1270,8 @@ public void replaceAll(BiFunction<? super K, ? super V, ? extends V> function) {
     }
 
     @Override
-    public @Nullable V remove(@Nullable Object key) {
+    @CheckForNull
+    public V remove(@CheckForNull Object key) {
       synchronized (mutex) {
         return delegate().remove(key);
       }
@@ -1232,7 +1279,7 @@ public void replaceAll(BiFunction<? super K, ? super V, ? extends V> function) {
 
     @Pure
     @Override
-    public boolean remove(Object key, Object value) {
+    public boolean remove(@CheckForNull Object key, @CheckForNull Object value) {
       synchronized (mutex) {
         return delegate().remove(key, value);
       }
@@ -1258,7 +1305,7 @@ public Collection<V> values() {
 
     @Pure
     @Override
-    public boolean equals(@Nullable Object o) {
+    public boolean equals(@CheckForNull Object o) {
       if (o == this) {
         return true;
       }
@@ -1278,14 +1325,15 @@ public int hashCode() {
     private static final long serialVersionUID = 0;
   }
 
-  static <K, V> SortedMap<K, V> sortedMap(SortedMap<K, V> sortedMap, @Nullable Object mutex) {
+  static <K extends @Nullable Object, V extends @Nullable Object> SortedMap<K, V> sortedMap(
+      SortedMap<K, V> sortedMap, @CheckForNull Object mutex) {
     return new SynchronizedSortedMap<>(sortedMap, mutex);
   }
 
-  static class SynchronizedSortedMap<K, V> extends SynchronizedMap<K, V>
-      implements SortedMap<K, V> {
+  static class SynchronizedSortedMap<K extends @Nullable Object, V extends @Nullable Object>
+      extends SynchronizedMap<K, V> implements SortedMap<K, V> {
 
-    SynchronizedSortedMap(SortedMap<K, V> delegate, @Nullable Object mutex) {
+    SynchronizedSortedMap(SortedMap<K, V> delegate, @CheckForNull Object mutex) {
       super(delegate, mutex);
     }
 
@@ -1295,6 +1343,7 @@ SortedMap<K, V> delegate() {
     }
 
     @Override
+    @CheckForNull
     public Comparator<? super K> comparator() {
       synchronized (mutex) {
         return delegate().comparator();
@@ -1339,7 +1388,8 @@ public SortedMap<K, V> tailMap(K fromKey) {
     private static final long serialVersionUID = 0;
   }
 
-  static <K, V> BiMap<K, V> biMap(BiMap<K, V> bimap, @Nullable Object mutex) {
+  static <K extends @Nullable Object, V extends @Nullable Object> BiMap<K, V> biMap(
+      BiMap<K, V> bimap, @CheckForNull Object mutex) {
     if (bimap instanceof SynchronizedBiMap || bimap instanceof ImmutableBiMap) {
       return bimap;
     }
@@ -1347,13 +1397,13 @@ static <K, V> BiMap<K, V> biMap(BiMap<K, V> bimap, @Nullable Object mutex) {
   }
 
   @VisibleForTesting
-  static class SynchronizedBiMap<K, V> extends SynchronizedMap<K, V>
-      implements BiMap<K, V>, Serializable {
-    private transient @Nullable Set<V> valueSet;
-    @RetainedWith private transient @Nullable BiMap<V, K> inverse;
+  static class SynchronizedBiMap<K extends @Nullable Object, V extends @Nullable Object>
+      extends SynchronizedMap<K, V> implements BiMap<K, V>, Serializable {
+    @CheckForNull private transient Set<V> valueSet;
+    @RetainedWith @CheckForNull private transient BiMap<V, K> inverse;
 
     private SynchronizedBiMap(
-        BiMap<K, V> delegate, @Nullable Object mutex, @Nullable BiMap<V, K> inverse) {
+        BiMap<K, V> delegate, @CheckForNull Object mutex, @CheckForNull BiMap<V, K> inverse) {
       super(delegate, mutex);
       this.inverse = inverse;
     }
@@ -1375,6 +1425,7 @@ public Set<V> values() {
     }
 
     @Override
+    @CheckForNull
     public V forcePut(K key, V value) {
       synchronized (mutex) {
         return delegate().forcePut(key, value);
@@ -1394,16 +1445,18 @@ public BiMap<V, K> inverse() {
     private static final long serialVersionUID = 0;
   }
 
-  private static class SynchronizedAsMap<K, V> extends SynchronizedMap<K, Collection<V>> {
-    transient @Nullable Set<Entry<K, Collection<V>>> asMapEntrySet;
-    transient @Nullable Collection<Collection<V>> asMapValues;
+  private static class SynchronizedAsMap<K extends @Nullable Object, V extends @Nullable Object>
+      extends SynchronizedMap<K, Collection<V>> {
+    @CheckForNull transient Set<Map.Entry<K, Collection<V>>> asMapEntrySet;
+    @CheckForNull transient Collection<Collection<V>> asMapValues;
 
-    SynchronizedAsMap(Map<K, Collection<V>> delegate, @Nullable Object mutex) {
+    SynchronizedAsMap(Map<K, Collection<V>> delegate, @CheckForNull Object mutex) {
       super(delegate, mutex);
     }
 
     @Override
-    public @Nullable Collection<V> get(@Nullable Object key) {
+    @CheckForNull
+    public Collection<V> get(@CheckForNull Object key) {
       synchronized (mutex) {
         Collection<V> collection = super.get(key);
         return (collection == null) ? null : typePreservingCollection(collection, mutex);
@@ -1412,7 +1465,7 @@ private static class SynchronizedAsMap<K, V> extends SynchronizedMap<K, Collecti
 
     @SideEffectFree
     @Override
-    public Set<Entry<K, Collection<V>>> entrySet() {
+    public Set<Map.Entry<K, Collection<V>>> entrySet() {
       synchronized (mutex) {
         if (asMapEntrySet == null) {
           asMapEntrySet = new SynchronizedAsMapEntries<>(delegate().entrySet(), mutex);
@@ -1434,7 +1487,7 @@ public Collection<Collection<V>> values() {
 
     @Pure
     @Override
-    public boolean containsValue(@Nullable Object o) {
+    public boolean containsValue(@CheckForNull Object o) {
       // values() and its contains() method are both synchronized.
       return values().contains(o);
     }
@@ -1442,8 +1495,9 @@ public boolean containsValue(@Nullable Object o) {
     private static final long serialVersionUID = 0;
   }
 
-  private static class SynchronizedAsMapValues<V> extends SynchronizedCollection<Collection<V>> {
-    SynchronizedAsMapValues(Collection<Collection<V>> delegate, @Nullable Object mutex) {
+  private static class SynchronizedAsMapValues<V extends @Nullable Object>
+      extends SynchronizedCollection<Collection<V>> {
+    SynchronizedAsMapValues(Collection<Collection<V>> delegate, @CheckForNull Object mutex) {
       super(delegate, mutex);
     }
 
@@ -1492,9 +1546,9 @@ Collection<V> transform(Collection<V> from) {
 
   @GwtIncompatible // NavigableSet
   @VisibleForTesting
-  static class SynchronizedNavigableSet<E> extends SynchronizedSortedSet<E>
+  static class SynchronizedNavigableSet<E extends @Nullable Object> extends SynchronizedSortedSet<E>
       implements NavigableSet<E> {
-    SynchronizedNavigableSet(NavigableSet<E> delegate, @Nullable Object mutex) {
+    SynchronizedNavigableSet(NavigableSet<E> delegate, @CheckForNull Object mutex) {
       super(delegate, mutex);
     }
 
@@ -1504,6 +1558,7 @@ NavigableSet<E> delegate() {
     }
 
     @Override
+    @CheckForNull
     public E ceiling(E e) {
       synchronized (mutex) {
         return delegate().ceiling(e);
@@ -1515,7 +1570,7 @@ public Iterator<E> descendingIterator() {
       return delegate().descendingIterator(); // manually synchronized
     }
 
-    transient @Nullable NavigableSet<E> descendingSet;
+    @CheckForNull transient NavigableSet<E> descendingSet;
 
     @Override
     public NavigableSet<E> descendingSet() {
@@ -1530,6 +1585,7 @@ public NavigableSet<E> descendingSet() {
     }
 
     @Override
+    @CheckForNull
     public E floor(E e) {
       synchronized (mutex) {
         return delegate().floor(e);
@@ -1549,6 +1605,7 @@ public SortedSet<E> headSet(E toElement) {
     }
 
     @Override
+    @CheckForNull
     public E higher(E e) {
       synchronized (mutex) {
         return delegate().higher(e);
@@ -1556,6 +1613,7 @@ public E higher(E e) {
     }
 
     @Override
+    @CheckForNull
     public E lower(E e) {
       synchronized (mutex) {
         return delegate().lower(e);
@@ -1563,6 +1621,7 @@ public E lower(E e) {
     }
 
     @Override
+    @CheckForNull
     public E pollFirst() {
       synchronized (mutex) {
         return delegate().pollFirst();
@@ -1570,6 +1629,7 @@ public E pollFirst() {
     }
 
     @Override
+    @CheckForNull
     public E pollLast() {
       synchronized (mutex) {
         return delegate().pollLast();
@@ -1606,32 +1666,34 @@ public SortedSet<E> tailSet(E fromElement) {
   }
 
   @GwtIncompatible // NavigableSet
-  static <E> NavigableSet<E> navigableSet(NavigableSet<E> navigableSet, @Nullable Object mutex) {
+  static <E extends @Nullable Object> NavigableSet<E> navigableSet(
+      NavigableSet<E> navigableSet, @CheckForNull Object mutex) {
     return new SynchronizedNavigableSet<E>(navigableSet, mutex);
   }
 
   @GwtIncompatible // NavigableSet
-  static <E> NavigableSet<E> navigableSet(NavigableSet<E> navigableSet) {
+  static <E extends @Nullable Object> NavigableSet<E> navigableSet(NavigableSet<E> navigableSet) {
     return navigableSet(navigableSet, null);
   }
 
   @GwtIncompatible // NavigableMap
-  static <K, V> NavigableMap<K, V> navigableMap(NavigableMap<K, V> navigableMap) {
+  static <K extends @Nullable Object, V extends @Nullable Object> NavigableMap<K, V> navigableMap(
+      NavigableMap<K, V> navigableMap) {
     return navigableMap(navigableMap, null);
   }
 
   @GwtIncompatible // NavigableMap
-  static <K, V> NavigableMap<K, V> navigableMap(
-      NavigableMap<K, V> navigableMap, @Nullable Object mutex) {
+  static <K extends @Nullable Object, V extends @Nullable Object> NavigableMap<K, V> navigableMap(
+      NavigableMap<K, V> navigableMap, @CheckForNull Object mutex) {
     return new SynchronizedNavigableMap<>(navigableMap, mutex);
   }
 
   @GwtIncompatible // NavigableMap
   @VisibleForTesting
-  static class SynchronizedNavigableMap<K, V> extends SynchronizedSortedMap<K, V>
-      implements NavigableMap<K, V> {
+  static class SynchronizedNavigableMap<K extends @Nullable Object, V extends @Nullable Object>
+      extends SynchronizedSortedMap<K, V> implements NavigableMap<K, V> {
 
-    SynchronizedNavigableMap(NavigableMap<K, V> delegate, @Nullable Object mutex) {
+    SynchronizedNavigableMap(NavigableMap<K, V> delegate, @CheckForNull Object mutex) {
       super(delegate, mutex);
     }
 
@@ -1641,20 +1703,22 @@ NavigableMap<K, V> delegate() {
     }
 
     @Override
-    public Entry<K, V> ceilingEntry(K key) {
+    @CheckForNull
+    public Map.Entry<K, V> ceilingEntry(K key) {
       synchronized (mutex) {
         return nullableSynchronizedEntry(delegate().ceilingEntry(key), mutex);
       }
     }
 
     @Override
+    @CheckForNull
     public K ceilingKey(K key) {
       synchronized (mutex) {
         return delegate().ceilingKey(key);
       }
     }
 
-    transient @Nullable NavigableSet<K> descendingKeySet;
+    @CheckForNull transient NavigableSet<K> descendingKeySet;
 
     @Override
     public NavigableSet<K> descendingKeySet() {
@@ -1666,7 +1730,7 @@ public NavigableSet<K> descendingKeySet() {
       }
     }
 
-    transient @Nullable NavigableMap<K, V> descendingMap;
+    @CheckForNull transient NavigableMap<K, V> descendingMap;
 
     @Override
     public NavigableMap<K, V> descendingMap() {
@@ -1679,20 +1743,23 @@ public NavigableMap<K, V> descendingMap() {
     }
 
     @Override
-    public Entry<K, V> firstEntry() {
+    @CheckForNull
+    public Map.Entry<K, V> firstEntry() {
       synchronized (mutex) {
         return nullableSynchronizedEntry(delegate().firstEntry(), mutex);
       }
     }
 
     @Override
-    public Entry<K, V> floorEntry(K key) {
+    @CheckForNull
+    public Map.Entry<K, V> floorEntry(K key) {
       synchronized (mutex) {
         return nullableSynchronizedEntry(delegate().floorEntry(key), mutex);
       }
     }
 
     @Override
+    @CheckForNull
     public K floorKey(K key) {
       synchronized (mutex) {
         return delegate().floorKey(key);
@@ -1712,13 +1779,15 @@ public SortedMap<K, V> headMap(K toKey) {
     }
 
     @Override
-    public Entry<K, V> higherEntry(K key) {
+    @CheckForNull
+    public Map.Entry<K, V> higherEntry(K key) {
       synchronized (mutex) {
         return nullableSynchronizedEntry(delegate().higherEntry(key), mutex);
       }
     }
 
     @Override
+    @CheckForNull
     public K higherKey(K key) {
       synchronized (mutex) {
         return delegate().higherKey(key);
@@ -1726,20 +1795,23 @@ public K higherKey(K key) {
     }
 
     @Override
-    public Entry<K, V> lastEntry() {
+    @CheckForNull
+    public Map.Entry<K, V> lastEntry() {
       synchronized (mutex) {
         return nullableSynchronizedEntry(delegate().lastEntry(), mutex);
       }
     }
 
     @Override
-    public Entry<K, V> lowerEntry(K key) {
+    @CheckForNull
+    public Map.Entry<K, V> lowerEntry(K key) {
       synchronized (mutex) {
         return nullableSynchronizedEntry(delegate().lowerEntry(key), mutex);
       }
     }
 
     @Override
+    @CheckForNull
     public K lowerKey(K key) {
       synchronized (mutex) {
         return delegate().lowerKey(key);
@@ -1751,7 +1823,7 @@ public Set<K> keySet() {
       return navigableKeySet();
     }
 
-    transient @Nullable NavigableSet<K> navigableKeySet;
+    @CheckForNull transient NavigableSet<K> navigableKeySet;
 
     @Override
     public NavigableSet<K> navigableKeySet() {
@@ -1764,14 +1836,16 @@ public NavigableSet<K> navigableKeySet() {
     }
 
     @Override
-    public Entry<K, V> pollFirstEntry() {
+    @CheckForNull
+    public Map.Entry<K, V> pollFirstEntry() {
       synchronized (mutex) {
         return nullableSynchronizedEntry(delegate().pollFirstEntry(), mutex);
       }
     }
 
     @Override
-    public Entry<K, V> pollLastEntry() {
+    @CheckForNull
+    public Map.Entry<K, V> pollLastEntry() {
       synchronized (mutex) {
         return nullableSynchronizedEntry(delegate().pollLastEntry(), mutex);
       }
@@ -1806,8 +1880,10 @@ public SortedMap<K, V> tailMap(K fromKey) {
   }
 
   @GwtIncompatible // works but is needed only for NavigableMap
-  private static <K, V> Entry<K, V> nullableSynchronizedEntry(
-      @Nullable Entry<K, V> entry, @Nullable Object mutex) {
+  @CheckForNull
+  private static <K extends @Nullable Object, V extends @Nullable Object>
+      Map.Entry<K, V> nullableSynchronizedEntry(
+          @CheckForNull Map.Entry<K, V> entry, @CheckForNull Object mutex) {
     if (entry == null) {
       return null;
     }
@@ -1815,20 +1891,21 @@ private static <K, V> Entry<K, V> nullableSynchronizedEntry(
   }
 
   @GwtIncompatible // works but is needed only for NavigableMap
-  private static class SynchronizedEntry<K, V> extends SynchronizedObject implements Entry<K, V> {
+  private static class SynchronizedEntry<K extends @Nullable Object, V extends @Nullable Object>
+      extends SynchronizedObject implements Map.Entry<K, V> {
 
-    SynchronizedEntry(Entry<K, V> delegate, @Nullable Object mutex) {
+    SynchronizedEntry(Map.Entry<K, V> delegate, @CheckForNull Object mutex) {
       super(delegate, mutex);
     }
 
     @SuppressWarnings("unchecked") // guaranteed by the constructor
     @Override
-    Entry<K, V> delegate() {
-      return (Entry<K, V>) super.delegate();
+    Map.Entry<K, V> delegate() {
+      return (Map.Entry<K, V>) super.delegate();
     }
 
     @Override
-    public boolean equals(Object obj) {
+    public boolean equals(@CheckForNull Object obj) {
       synchronized (mutex) {
         return delegate().equals(obj);
       }
@@ -1865,13 +1942,14 @@ public V setValue(V value) {
     private static final long serialVersionUID = 0;
   }
 
-  static <E> Queue<E> queue(Queue<E> queue, @Nullable Object mutex) {
+  static <E extends @Nullable Object> Queue<E> queue(Queue<E> queue, @CheckForNull Object mutex) {
     return (queue instanceof SynchronizedQueue) ? queue : new SynchronizedQueue<E>(queue, mutex);
   }
 
-  private static class SynchronizedQueue<E> extends SynchronizedCollection<E> implements Queue<E> {
+  private static class SynchronizedQueue<E extends @Nullable Object>
+      extends SynchronizedCollection<E> implements Queue<E> {
 
-    SynchronizedQueue(Queue<E> delegate, @Nullable Object mutex) {
+    SynchronizedQueue(Queue<E> delegate, @CheckForNull Object mutex) {
       super(delegate, mutex);
     }
 
@@ -1895,6 +1973,7 @@ public boolean offer(E e) {
     }
 
     @Override
+    @CheckForNull
     public E peek() {
       synchronized (mutex) {
         return delegate().peek();
@@ -1902,6 +1981,7 @@ public E peek() {
     }
 
     @Override
+    @CheckForNull
     public E poll() {
       synchronized (mutex) {
         return delegate().poll();
@@ -1918,13 +1998,14 @@ public E remove() {
     private static final long serialVersionUID = 0;
   }
 
-  static <E> Deque<E> deque(Deque<E> deque, @Nullable Object mutex) {
+  static <E extends @Nullable Object> Deque<E> deque(Deque<E> deque, @CheckForNull Object mutex) {
     return new SynchronizedDeque<E>(deque, mutex);
   }
 
-  private static final class SynchronizedDeque<E> extends SynchronizedQueue<E> implements Deque<E> {
+  private static final class SynchronizedDeque<E extends @Nullable Object>
+      extends SynchronizedQueue<E> implements Deque<E> {
 
-    SynchronizedDeque(Deque<E> delegate, @Nullable Object mutex) {
+    SynchronizedDeque(Deque<E> delegate, @CheckForNull Object mutex) {
       super(delegate, mutex);
     }
 
@@ -1976,6 +2057,7 @@ public E removeLast() {
     }
 
     @Override
+    @CheckForNull
     public E pollFirst() {
       synchronized (mutex) {
         return delegate().pollFirst();
@@ -1983,6 +2065,7 @@ public E pollFirst() {
     }
 
     @Override
+    @CheckForNull
     public E pollLast() {
       synchronized (mutex) {
         return delegate().pollLast();
@@ -2004,6 +2087,7 @@ public E getLast() {
     }
 
     @Override
+    @CheckForNull
     public E peekFirst() {
       synchronized (mutex) {
         return delegate().peekFirst();
@@ -2011,6 +2095,7 @@ public E peekFirst() {
     }
 
     @Override
+    @CheckForNull
     public E peekLast() {
       synchronized (mutex) {
         return delegate().peekLast();
@@ -2018,14 +2103,14 @@ public E peekLast() {
     }
 
     @Override
-    public boolean removeFirstOccurrence(Object o) {
+    public boolean removeFirstOccurrence(@CheckForNull Object o) {
       synchronized (mutex) {
         return delegate().removeFirstOccurrence(o);
       }
     }
 
     @Override
-    public boolean removeLastOccurrence(Object o) {
+    public boolean removeLastOccurrence(@CheckForNull Object o) {
       synchronized (mutex) {
         return delegate().removeLastOccurrence(o);
       }
@@ -2055,14 +2140,16 @@ public Iterator<E> descendingIterator() {
     private static final long serialVersionUID = 0;
   }
 
-  static <R, C, V> Table<R, C, V> table(Table<R, C, V> table, Object mutex) {
+  static <R extends @Nullable Object, C extends @Nullable Object, V extends @Nullable Object>
+      Table<R, C, V> table(Table<R, C, V> table, @CheckForNull Object mutex) {
     return new SynchronizedTable<>(table, mutex);
   }
 
-  private static final class SynchronizedTable<R, C, V> extends SynchronizedObject
-      implements Table<R, C, V> {
+  private static final class SynchronizedTable<
+          R extends @Nullable Object, C extends @Nullable Object, V extends @Nullable Object>
+      extends SynchronizedObject implements Table<R, C, V> {
 
-    SynchronizedTable(Table<R, C, V> delegate, Object mutex) {
+    SynchronizedTable(Table<R, C, V> delegate, @CheckForNull Object mutex) {
       super(delegate, mutex);
     }
 
@@ -2073,35 +2160,36 @@ Table<R, C, V> delegate() {
     }
 
     @Override
-    public boolean contains(@Nullable Object rowKey, @Nullable Object columnKey) {
+    public boolean contains(@CheckForNull Object rowKey, @CheckForNull Object columnKey) {
       synchronized (mutex) {
         return delegate().contains(rowKey, columnKey);
       }
     }
 
     @Override
-    public boolean containsRow(@Nullable Object rowKey) {
+    public boolean containsRow(@CheckForNull Object rowKey) {
       synchronized (mutex) {
         return delegate().containsRow(rowKey);
       }
     }
 
     @Override
-    public boolean containsColumn(@Nullable Object columnKey) {
+    public boolean containsColumn(@CheckForNull Object columnKey) {
       synchronized (mutex) {
         return delegate().containsColumn(columnKey);
       }
     }
 
     @Override
-    public boolean containsValue(@Nullable Object value) {
+    public boolean containsValue(@CheckForNull Object value) {
       synchronized (mutex) {
         return delegate().containsValue(value);
       }
     }
 
     @Override
-    public V get(@Nullable Object rowKey, @Nullable Object columnKey) {
+    @CheckForNull
+    public V get(@CheckForNull Object rowKey, @CheckForNull Object columnKey) {
       synchronized (mutex) {
         return delegate().get(rowKey, columnKey);
       }
@@ -2129,7 +2217,8 @@ public void clear() {
     }
 
     @Override
-    public V put(@Nullable R rowKey, @Nullable C columnKey, @Nullable V value) {
+    @CheckForNull
+    public V put(R rowKey, C columnKey, V value) {
       synchronized (mutex) {
         return delegate().put(rowKey, columnKey, value);
       }
@@ -2143,21 +2232,22 @@ public void putAll(Table<? extends R, ? extends C, ? extends V> table) {
     }
 
     @Override
-    public V remove(@Nullable Object rowKey, @Nullable Object columnKey) {
+    @CheckForNull
+    public V remove(@CheckForNull Object rowKey, @CheckForNull Object columnKey) {
       synchronized (mutex) {
         return delegate().remove(rowKey, columnKey);
       }
     }
 
     @Override
-    public Map<C, V> row(@Nullable R rowKey) {
+    public Map<C, V> row(R rowKey) {
       synchronized (mutex) {
         return map(delegate().row(rowKey), mutex);
       }
     }
 
     @Override
-    public Map<R, V> column(@Nullable C columnKey) {
+    public Map<R, V> column(C columnKey) {
       synchronized (mutex) {
         return map(delegate().column(columnKey), mutex);
       }
@@ -2231,7 +2321,7 @@ public int hashCode() {
     }
 
     @Override
-    public boolean equals(@Nullable Object obj) {
+    public boolean equals(@CheckForNull Object obj) {
       if (this == obj) {
         return true;
       }
diff --git a/guava/src/com/google/common/collect/Table.java b/guava/src/com/google/common/collect/Table.java
index bb9448adc7ec..3c9e7ec7a471 100644
--- a/guava/src/com/google/common/collect/Table.java
+++ b/guava/src/com/google/common/collect/Table.java
@@ -24,6 +24,7 @@
 import java.util.Collection;
 import java.util.Map;
 import java.util.Set;
+import javax.annotation.CheckForNull;
 import org.checkerframework.checker.nullness.qual.Nullable;
 
 /**
@@ -45,7 +46,7 @@
  * UnsupportedOperationException}.
  *
  * <p>See the Guava User Guide article on <a href=
- * "https://github.com/google/guava/wiki/NewCollectionTypesExplained#table"> {@code Table}</a>.
+ * "https://github.com/google/guava/wiki/NewCollectionTypesExplained#table">{@code Table}</a>.
  *
  * @author Jared Levy
  * @param <R> the type of the table row keys
@@ -55,7 +56,9 @@
  */
 @DoNotMock("Use ImmutableTable, HashBasedTable, or another implementation")
 @GwtCompatible
-public interface Table<R, C, V> {
+@ElementTypesAreNonnullByDefault
+public interface Table<
+    R extends @Nullable Object, C extends @Nullable Object, V extends @Nullable Object> {
   // TODO(jlevy): Consider adding methods similar to ConcurrentMap methods.
 
   // Accessors
@@ -67,29 +70,29 @@ public interface Table<R, C, V> {
    * @param columnKey key of column to search for
    */
   boolean contains(
-      @CompatibleWith("R") @Nullable Object rowKey,
-      @CompatibleWith("C") @Nullable Object columnKey);
+      @CompatibleWith("R") @CheckForNull Object rowKey,
+      @CompatibleWith("C") @CheckForNull Object columnKey);
 
   /**
    * Returns {@code true} if the table contains a mapping with the specified row key.
    *
    * @param rowKey key of row to search for
    */
-  boolean containsRow(@CompatibleWith("R") @Nullable Object rowKey);
+  boolean containsRow(@CompatibleWith("R") @CheckForNull Object rowKey);
 
   /**
    * Returns {@code true} if the table contains a mapping with the specified column.
    *
    * @param columnKey key of column to search for
    */
-  boolean containsColumn(@CompatibleWith("C") @Nullable Object columnKey);
+  boolean containsColumn(@CompatibleWith("C") @CheckForNull Object columnKey);
 
   /**
    * Returns {@code true} if the table contains a mapping with the specified value.
    *
    * @param value value to search for
    */
-  boolean containsValue(@CompatibleWith("V") @Nullable Object value);
+  boolean containsValue(@CompatibleWith("V") @CheckForNull Object value);
 
   /**
    * Returns the value corresponding to the given row and column keys, or {@code null} if no such
@@ -98,10 +101,10 @@ boolean contains(
    * @param rowKey key of row to search for
    * @param columnKey key of column to search for
    */
-  @Nullable
+  @CheckForNull
   V get(
-      @CompatibleWith("R") @Nullable Object rowKey,
-      @CompatibleWith("C") @Nullable Object columnKey);
+      @CompatibleWith("R") @CheckForNull Object rowKey,
+      @CompatibleWith("C") @CheckForNull Object columnKey);
 
   /** Returns {@code true} if the table contains no mappings. */
   boolean isEmpty();
@@ -114,7 +117,7 @@ V get(
    * cell views, as returned by {@link #cellSet}, are equal.
    */
   @Override
-  boolean equals(@Nullable Object obj);
+  boolean equals(@CheckForNull Object obj);
 
   /**
    * Returns the hash code for this table. The hash code of a table is defined as the hash code of
@@ -139,8 +142,8 @@ V get(
    *     for the keys
    */
   @CanIgnoreReturnValue
-  @Nullable
-  V put(R rowKey, C columnKey, V value);
+  @CheckForNull
+  V put(@ParametricNullness R rowKey, @ParametricNullness C columnKey, @ParametricNullness V value);
 
   /**
    * Copies all mappings from the specified table to this table. The effect is equivalent to calling
@@ -158,10 +161,10 @@ V get(
    * @return the value previously associated with the keys, or {@code null} if no such value existed
    */
   @CanIgnoreReturnValue
-  @Nullable
+  @CheckForNull
   V remove(
-      @CompatibleWith("R") @Nullable Object rowKey,
-      @CompatibleWith("C") @Nullable Object columnKey);
+      @CompatibleWith("R") @CheckForNull Object rowKey,
+      @CompatibleWith("C") @CheckForNull Object columnKey);
 
   // Views
 
@@ -175,7 +178,7 @@ V remove(
    * @param rowKey key of row to search for in the table
    * @return the corresponding map from column keys to values
    */
-  Map<C, V> row(R rowKey);
+  Map<C, V> row(@ParametricNullness R rowKey);
 
   /**
    * Returns a view of all mappings that have the given column key. For each row key / column key /
@@ -187,7 +190,7 @@ V remove(
    * @param columnKey key of column to search for in the table
    * @return the corresponding map from row keys to values
    */
-  Map<R, V> column(C columnKey);
+  Map<R, V> column(@ParametricNullness C columnKey);
 
   /**
    * Returns a set of all row key / column key / value triplets. Changes to the returned set will
@@ -253,17 +256,18 @@ V remove(
    *
    * @since 7.0
    */
-  interface Cell<R, C, V> {
+  interface Cell<
+      R extends @Nullable Object, C extends @Nullable Object, V extends @Nullable Object> {
     /** Returns the row key of this cell. */
-    @Nullable
+    @ParametricNullness
     R getRowKey();
 
     /** Returns the column key of this cell. */
-    @Nullable
+    @ParametricNullness
     C getColumnKey();
 
     /** Returns the value of this cell. */
-    @Nullable
+    @ParametricNullness
     V getValue();
 
     /**
@@ -271,7 +275,7 @@ interface Cell<R, C, V> {
      * equal row keys, column keys, and values.
      */
     @Override
-    boolean equals(@Nullable Object obj);
+    boolean equals(@CheckForNull Object obj);
 
     /**
      * Returns the hash code of this cell.
diff --git a/guava/src/com/google/common/collect/TableCollectors.java b/guava/src/com/google/common/collect/TableCollectors.java
index 869aa4e71c3d..16fcb166969a 100644
--- a/guava/src/com/google/common/collect/TableCollectors.java
+++ b/guava/src/com/google/common/collect/TableCollectors.java
@@ -26,15 +26,18 @@
 import java.util.function.Function;
 import java.util.function.Supplier;
 import java.util.stream.Collector;
+import org.checkerframework.checker.nullness.qual.Nullable;
 
 /** Collectors utilities for {@code common.collect.Table} internals. */
 @GwtCompatible
+@ElementTypesAreNonnullByDefault
 final class TableCollectors {
 
-  static <T, R, C, V> Collector<T, ?, ImmutableTable<R, C, V>> toImmutableTable(
-      Function<? super T, ? extends R> rowFunction,
-      Function<? super T, ? extends C> columnFunction,
-      Function<? super T, ? extends V> valueFunction) {
+  static <T extends @Nullable Object, R, C, V>
+      Collector<T, ?, ImmutableTable<R, C, V>> toImmutableTable(
+          Function<? super T, ? extends R> rowFunction,
+          Function<? super T, ? extends C> columnFunction,
+          Function<? super T, ? extends V> valueFunction) {
     checkNotNull(rowFunction, "rowFunction");
     checkNotNull(columnFunction, "columnFunction");
     checkNotNull(valueFunction, "valueFunction");
@@ -46,11 +49,12 @@ final class TableCollectors {
         ImmutableTable.Builder::build);
   }
 
-  static <T, R, C, V> Collector<T, ?, ImmutableTable<R, C, V>> toImmutableTable(
-      Function<? super T, ? extends R> rowFunction,
-      Function<? super T, ? extends C> columnFunction,
-      Function<? super T, ? extends V> valueFunction,
-      BinaryOperator<V> mergeFunction) {
+  static <T extends @Nullable Object, R, C, V>
+      Collector<T, ?, ImmutableTable<R, C, V>> toImmutableTable(
+          Function<? super T, ? extends R> rowFunction,
+          Function<? super T, ? extends C> columnFunction,
+          Function<? super T, ? extends V> valueFunction,
+          BinaryOperator<V> mergeFunction) {
 
     checkNotNull(rowFunction, "rowFunction");
     checkNotNull(columnFunction, "columnFunction");
@@ -64,8 +68,7 @@ final class TableCollectors {
      */
 
     return Collector.of(
-        () -> new ImmutableTableCollectorState<R, C, V>()
-        /* GWT isn't currently playing nicely with constructor references? */ ,
+        ImmutableTableCollectorState<R, C, V>::new,
         (state, input) ->
             state.put(
                 rowFunction.apply(input),
@@ -76,11 +79,17 @@ final class TableCollectors {
         state -> state.toTable());
   }
 
-  static <T, R, C, V, I extends Table<R, C, V>> Collector<T, ?, I> toTable(
-      java.util.function.Function<? super T, ? extends R> rowFunction,
-      java.util.function.Function<? super T, ? extends C> columnFunction,
-      java.util.function.Function<? super T, ? extends V> valueFunction,
-      java.util.function.Supplier<I> tableSupplier) {
+  static <
+          T extends @Nullable Object,
+          R extends @Nullable Object,
+          C extends @Nullable Object,
+          V extends @Nullable Object,
+          I extends Table<R, C, V>>
+      Collector<T, ?, I> toTable(
+          java.util.function.Function<? super T, ? extends R> rowFunction,
+          java.util.function.Function<? super T, ? extends C> columnFunction,
+          java.util.function.Function<? super T, ? extends V> valueFunction,
+          java.util.function.Supplier<I> tableSupplier) {
     return toTable(
         rowFunction,
         columnFunction,
@@ -91,12 +100,18 @@ final class TableCollectors {
         tableSupplier);
   }
 
-  static <T, R, C, V, I extends Table<R, C, V>> Collector<T, ?, I> toTable(
-      java.util.function.Function<? super T, ? extends R> rowFunction,
-      java.util.function.Function<? super T, ? extends C> columnFunction,
-      java.util.function.Function<? super T, ? extends V> valueFunction,
-      BinaryOperator<V> mergeFunction,
-      java.util.function.Supplier<I> tableSupplier) {
+  static <
+          T extends @Nullable Object,
+          R extends @Nullable Object,
+          C extends @Nullable Object,
+          V extends @Nullable Object,
+          I extends Table<R, C, V>>
+      Collector<T, ?, I> toTable(
+          java.util.function.Function<? super T, ? extends R> rowFunction,
+          java.util.function.Function<? super T, ? extends C> columnFunction,
+          java.util.function.Function<? super T, ? extends V> valueFunction,
+          BinaryOperator<V> mergeFunction,
+          java.util.function.Supplier<I> tableSupplier) {
     checkNotNull(rowFunction);
     checkNotNull(columnFunction);
     checkNotNull(valueFunction);
@@ -180,8 +195,14 @@ void merge(V value, BinaryOperator<V> mergeFunction) {
     }
   }
 
-  private static <R, C, V> void mergeTables(
-      Table<R, C, V> table, R row, C column, V value, BinaryOperator<V> mergeFunction) {
+  private static <
+          R extends @Nullable Object, C extends @Nullable Object, V extends @Nullable Object>
+      void mergeTables(
+          Table<R, C, V> table,
+          @ParametricNullness R row,
+          @ParametricNullness C column,
+          @ParametricNullness V value,
+          BinaryOperator<V> mergeFunction) {
     checkNotNull(value);
     V oldValue = table.get(row, column);
     if (oldValue == null) {
diff --git a/guava/src/com/google/common/collect/Tables.java b/guava/src/com/google/common/collect/Tables.java
index d1e88486698f..9c58611d41b5 100644
--- a/guava/src/com/google/common/collect/Tables.java
+++ b/guava/src/com/google/common/collect/Tables.java
@@ -18,6 +18,7 @@
 
 import static com.google.common.base.Preconditions.checkArgument;
 import static com.google.common.base.Preconditions.checkNotNull;
+import static com.google.common.collect.NullnessCasts.uncheckedCastNullableTToT;
 
 import com.google.common.annotations.Beta;
 import com.google.common.annotations.GwtCompatible;
@@ -36,19 +37,21 @@
 import java.util.Spliterator;
 import java.util.function.BinaryOperator;
 import java.util.stream.Collector;
+import javax.annotation.CheckForNull;
 import org.checkerframework.checker.nullness.qual.Nullable;
 
 /**
  * Provides static methods that involve a {@code Table}.
  *
  * <p>See the Guava User Guide article on <a href=
- * "https://github.com/google/guava/wiki/CollectionUtilitiesExplained#tables"> {@code Tables}</a>.
+ * "https://github.com/google/guava/wiki/CollectionUtilitiesExplained#tables">{@code Tables}</a>.
  *
  * @author Jared Levy
  * @author Louis Wasserman
  * @since 7.0
  */
 @GwtCompatible
+@ElementTypesAreNonnullByDefault
 public final class Tables {
   private Tables() {}
 
@@ -60,14 +63,22 @@ private Tables() {}
    * <p>If multiple input elements map to the same row and column, an {@code IllegalStateException}
    * is thrown when the collection operation is performed.
    *
+   * <p>To collect to an {@link ImmutableTable}, use {@link ImmutableTable#toImmutableTable}.
+   *
    * @since 21.0
    */
   @Beta
-  public static <T, R, C, V, I extends Table<R, C, V>> Collector<T, ?, I> toTable(
-      java.util.function.Function<? super T, ? extends R> rowFunction,
-      java.util.function.Function<? super T, ? extends C> columnFunction,
-      java.util.function.Function<? super T, ? extends V> valueFunction,
-      java.util.function.Supplier<I> tableSupplier) {
+  public static <
+          T extends @Nullable Object,
+          R extends @Nullable Object,
+          C extends @Nullable Object,
+          V extends @Nullable Object,
+          I extends Table<R, C, V>>
+      Collector<T, ?, I> toTable(
+          java.util.function.Function<? super T, ? extends R> rowFunction,
+          java.util.function.Function<? super T, ? extends C> columnFunction,
+          java.util.function.Function<? super T, ? extends V> valueFunction,
+          java.util.function.Supplier<I> tableSupplier) {
     return TableCollectors.toTable(rowFunction, columnFunction, valueFunction, tableSupplier);
   }
 
@@ -85,12 +96,18 @@ private Tables() {}
    *
    * @since 21.0
    */
-  public static <T, R, C, V, I extends Table<R, C, V>> Collector<T, ?, I> toTable(
-      java.util.function.Function<? super T, ? extends R> rowFunction,
-      java.util.function.Function<? super T, ? extends C> columnFunction,
-      java.util.function.Function<? super T, ? extends V> valueFunction,
-      BinaryOperator<V> mergeFunction,
-      java.util.function.Supplier<I> tableSupplier) {
+  public static <
+          T extends @Nullable Object,
+          R extends @Nullable Object,
+          C extends @Nullable Object,
+          V extends @Nullable Object,
+          I extends Table<R, C, V>>
+      Collector<T, ?, I> toTable(
+          java.util.function.Function<? super T, ? extends R> rowFunction,
+          java.util.function.Function<? super T, ? extends C> columnFunction,
+          java.util.function.Function<? super T, ? extends V> valueFunction,
+          BinaryOperator<V> mergeFunction,
+          java.util.function.Supplier<I> tableSupplier) {
     return TableCollectors.toTable(
         rowFunction, columnFunction, valueFunction, mergeFunction, tableSupplier);
   }
@@ -104,33 +121,44 @@ private Tables() {}
    * @param columnKey the column key to be associated with the returned cell
    * @param value the value to be associated with the returned cell
    */
-  public static <R, C, V> Cell<R, C, V> immutableCell(
-      @Nullable R rowKey, @Nullable C columnKey, @Nullable V value) {
+  public static <R extends @Nullable Object, C extends @Nullable Object, V extends @Nullable Object>
+      Cell<R, C, V> immutableCell(
+          @ParametricNullness R rowKey,
+          @ParametricNullness C columnKey,
+          @ParametricNullness V value) {
     return new ImmutableCell<>(rowKey, columnKey, value);
   }
 
-  static final class ImmutableCell<R, C, V> extends AbstractCell<R, C, V> implements Serializable {
-    private final @Nullable R rowKey;
-    private final @Nullable C columnKey;
-    private final @Nullable V value;
-
-    ImmutableCell(@Nullable R rowKey, @Nullable C columnKey, @Nullable V value) {
+  static final class ImmutableCell<
+          R extends @Nullable Object, C extends @Nullable Object, V extends @Nullable Object>
+      extends AbstractCell<R, C, V> implements Serializable {
+    @ParametricNullness private final R rowKey;
+    @ParametricNullness private final C columnKey;
+    @ParametricNullness private final V value;
+
+    ImmutableCell(
+        @ParametricNullness R rowKey,
+        @ParametricNullness C columnKey,
+        @ParametricNullness V value) {
       this.rowKey = rowKey;
       this.columnKey = columnKey;
       this.value = value;
     }
 
     @Override
+    @ParametricNullness
     public R getRowKey() {
       return rowKey;
     }
 
     @Override
+    @ParametricNullness
     public C getColumnKey() {
       return columnKey;
     }
 
     @Override
+    @ParametricNullness
     public V getValue() {
       return value;
     }
@@ -138,12 +166,14 @@ public V getValue() {
     private static final long serialVersionUID = 0;
   }
 
-  abstract static class AbstractCell<R, C, V> implements Cell<R, C, V> {
+  abstract static class AbstractCell<
+          R extends @Nullable Object, C extends @Nullable Object, V extends @Nullable Object>
+      implements Cell<R, C, V> {
     // needed for serialization
     AbstractCell() {}
 
     @Override
-    public boolean equals(Object obj) {
+    public boolean equals(@CheckForNull Object obj) {
       if (obj == this) {
         return true;
       }
@@ -179,13 +209,16 @@ public String toString() {
    * columnKeySet().iterator()} doesn't. With a transposed {@link HashBasedTable}, it's the other
    * way around.
    */
-  public static <R, C, V> Table<C, R, V> transpose(Table<R, C, V> table) {
+  public static <R extends @Nullable Object, C extends @Nullable Object, V extends @Nullable Object>
+      Table<C, R, V> transpose(Table<R, C, V> table) {
     return (table instanceof TransposeTable)
         ? ((TransposeTable<R, C, V>) table).original
         : new TransposeTable<C, R, V>(table);
   }
 
-  private static class TransposeTable<C, R, V> extends AbstractTable<C, R, V> {
+  private static class TransposeTable<
+          C extends @Nullable Object, R extends @Nullable Object, V extends @Nullable Object>
+      extends AbstractTable<C, R, V> {
     final Table<R, C, V> original;
 
     TransposeTable(Table<R, C, V> original) {
@@ -198,7 +231,7 @@ public void clear() {
     }
 
     @Override
-    public Map<C, V> column(R columnKey) {
+    public Map<C, V> column(@ParametricNullness R columnKey) {
       return original.row(columnKey);
     }
 
@@ -213,32 +246,37 @@ public Map<R, Map<C, V>> columnMap() {
     }
 
     @Override
-    public boolean contains(@Nullable Object rowKey, @Nullable Object columnKey) {
+    public boolean contains(@CheckForNull Object rowKey, @CheckForNull Object columnKey) {
       return original.contains(columnKey, rowKey);
     }
 
     @Override
-    public boolean containsColumn(@Nullable Object columnKey) {
+    public boolean containsColumn(@CheckForNull Object columnKey) {
       return original.containsRow(columnKey);
     }
 
     @Override
-    public boolean containsRow(@Nullable Object rowKey) {
+    public boolean containsRow(@CheckForNull Object rowKey) {
       return original.containsColumn(rowKey);
     }
 
     @Override
-    public boolean containsValue(@Nullable Object value) {
+    public boolean containsValue(@CheckForNull Object value) {
       return original.containsValue(value);
     }
 
     @Override
-    public V get(@Nullable Object rowKey, @Nullable Object columnKey) {
+    @CheckForNull
+    public V get(@CheckForNull Object rowKey, @CheckForNull Object columnKey) {
       return original.get(columnKey, rowKey);
     }
 
     @Override
-    public V put(C rowKey, R columnKey, V value) {
+    @CheckForNull
+    public V put(
+        @ParametricNullness C rowKey,
+        @ParametricNullness R columnKey,
+        @ParametricNullness V value) {
       return original.put(columnKey, rowKey, value);
     }
 
@@ -248,12 +286,13 @@ public void putAll(Table<? extends C, ? extends R, ? extends V> table) {
     }
 
     @Override
-    public V remove(@Nullable Object rowKey, @Nullable Object columnKey) {
+    @CheckForNull
+    public V remove(@CheckForNull Object rowKey, @CheckForNull Object columnKey) {
       return original.remove(columnKey, rowKey);
     }
 
     @Override
-    public Map<R, V> row(C rowKey) {
+    public Map<R, V> row(@ParametricNullness C rowKey) {
       return original.column(rowKey);
     }
 
@@ -368,12 +407,22 @@ public static <R, C, V> Table<R, C, V> newCustomTable(
    * @since 10.0
    */
   @Beta
-  public static <R, C, V1, V2> Table<R, C, V2> transformValues(
-      Table<R, C, V1> fromTable, Function<? super V1, V2> function) {
+  public static <
+          R extends @Nullable Object,
+          C extends @Nullable Object,
+          V1 extends @Nullable Object,
+          V2 extends @Nullable Object>
+      Table<R, C, V2> transformValues(
+          Table<R, C, V1> fromTable, Function<? super V1, V2> function) {
     return new TransformedTable<>(fromTable, function);
   }
 
-  private static class TransformedTable<R, C, V1, V2> extends AbstractTable<R, C, V2> {
+  private static class TransformedTable<
+          R extends @Nullable Object,
+          C extends @Nullable Object,
+          V1 extends @Nullable Object,
+          V2 extends @Nullable Object>
+      extends AbstractTable<R, C, V2> {
     final Table<R, C, V1> fromTable;
     final Function<? super V1, V2> function;
 
@@ -383,15 +432,19 @@ private static class TransformedTable<R, C, V1, V2> extends AbstractTable<R, C,
     }
 
     @Override
-    public boolean contains(Object rowKey, Object columnKey) {
+    public boolean contains(@CheckForNull Object rowKey, @CheckForNull Object columnKey) {
       return fromTable.contains(rowKey, columnKey);
     }
 
     @Override
-    public V2 get(Object rowKey, Object columnKey) {
+    @CheckForNull
+    public V2 get(@CheckForNull Object rowKey, @CheckForNull Object columnKey) {
       // The function is passed a null input only when the table contains a null
       // value.
-      return contains(rowKey, columnKey) ? function.apply(fromTable.get(rowKey, columnKey)) : null;
+      // The cast is safe because of the contains() check.
+      return contains(rowKey, columnKey)
+          ? function.apply(uncheckedCastNullableTToT(fromTable.get(rowKey, columnKey)))
+          : null;
     }
 
     @Override
@@ -405,7 +458,11 @@ public void clear() {
     }
 
     @Override
-    public V2 put(R rowKey, C columnKey, V2 value) {
+    @CheckForNull
+    public V2 put(
+        @ParametricNullness R rowKey,
+        @ParametricNullness C columnKey,
+        @ParametricNullness V2 value) {
       throw new UnsupportedOperationException();
     }
 
@@ -415,19 +472,21 @@ public void putAll(Table<? extends R, ? extends C, ? extends V2> table) {
     }
 
     @Override
-    public V2 remove(Object rowKey, Object columnKey) {
+    @CheckForNull
+    public V2 remove(@CheckForNull Object rowKey, @CheckForNull Object columnKey) {
       return contains(rowKey, columnKey)
-          ? function.apply(fromTable.remove(rowKey, columnKey))
+          // The cast is safe because of the contains() check.
+          ? function.apply(uncheckedCastNullableTToT(fromTable.remove(rowKey, columnKey)))
           : null;
     }
 
     @Override
-    public Map<C, V2> row(R rowKey) {
+    public Map<C, V2> row(@ParametricNullness R rowKey) {
       return Maps.transformValues(fromTable.row(rowKey), function);
     }
 
     @Override
-    public Map<R, V2> column(C columnKey) {
+    public Map<R, V2> column(@ParametricNullness C columnKey) {
       return Maps.transformValues(fromTable.column(columnKey), function);
     }
 
@@ -503,13 +562,14 @@ public Map<R, V2> apply(Map<R, V1> column) {
    *
    * @since 11.0
    */
-  public static <R, C, V> Table<R, C, V> unmodifiableTable(
-      Table<? extends R, ? extends C, ? extends V> table) {
+  public static <R extends @Nullable Object, C extends @Nullable Object, V extends @Nullable Object>
+      Table<R, C, V> unmodifiableTable(Table<? extends R, ? extends C, ? extends V> table) {
     return new UnmodifiableTable<>(table);
   }
 
-  private static class UnmodifiableTable<R, C, V> extends ForwardingTable<R, C, V>
-      implements Serializable {
+  private static class UnmodifiableTable<
+          R extends @Nullable Object, C extends @Nullable Object, V extends @Nullable Object>
+      extends ForwardingTable<R, C, V> implements Serializable {
     final Table<? extends R, ? extends C, ? extends V> delegate;
 
     UnmodifiableTable(Table<? extends R, ? extends C, ? extends V> delegate) {
@@ -533,7 +593,7 @@ public void clear() {
     }
 
     @Override
-    public Map<R, V> column(@Nullable C columnKey) {
+    public Map<R, V> column(@ParametricNullness C columnKey) {
       return Collections.unmodifiableMap(super.column(columnKey));
     }
 
@@ -549,7 +609,11 @@ public Map<C, Map<R, V>> columnMap() {
     }
 
     @Override
-    public V put(@Nullable R rowKey, @Nullable C columnKey, @Nullable V value) {
+    @CheckForNull
+    public V put(
+        @ParametricNullness R rowKey,
+        @ParametricNullness C columnKey,
+        @ParametricNullness V value) {
       throw new UnsupportedOperationException();
     }
 
@@ -559,12 +623,13 @@ public void putAll(Table<? extends R, ? extends C, ? extends V> table) {
     }
 
     @Override
-    public V remove(@Nullable Object rowKey, @Nullable Object columnKey) {
+    @CheckForNull
+    public V remove(@CheckForNull Object rowKey, @CheckForNull Object columnKey) {
       throw new UnsupportedOperationException();
     }
 
     @Override
-    public Map<C, V> row(@Nullable R rowKey) {
+    public Map<C, V> row(@ParametricNullness R rowKey) {
       return Collections.unmodifiableMap(super.row(rowKey));
     }
 
@@ -600,8 +665,9 @@ public Collection<V> values() {
    * @since 11.0
    */
   @Beta
-  public static <R, C, V> RowSortedTable<R, C, V> unmodifiableRowSortedTable(
-      RowSortedTable<R, ? extends C, ? extends V> table) {
+  public static <R extends @Nullable Object, C extends @Nullable Object, V extends @Nullable Object>
+      RowSortedTable<R, C, V> unmodifiableRowSortedTable(
+          RowSortedTable<R, ? extends C, ? extends V> table) {
     /*
      * It's not ? extends R, because it's technically not covariant in R. Specifically,
      * table.rowMap().comparator() could return a comparator that only works for the ? extends R.
@@ -610,8 +676,9 @@ public static <R, C, V> RowSortedTable<R, C, V> unmodifiableRowSortedTable(
     return new UnmodifiableRowSortedMap<>(table);
   }
 
-  static final class UnmodifiableRowSortedMap<R, C, V> extends UnmodifiableTable<R, C, V>
-      implements RowSortedTable<R, C, V> {
+  static final class UnmodifiableRowSortedMap<
+          R extends @Nullable Object, C extends @Nullable Object, V extends @Nullable Object>
+      extends UnmodifiableTable<R, C, V> implements RowSortedTable<R, C, V> {
 
     public UnmodifiableRowSortedMap(RowSortedTable<R, ? extends C, ? extends V> delegate) {
       super(delegate);
@@ -637,7 +704,8 @@ public SortedSet<R> rowKeySet() {
   }
 
   @SuppressWarnings("unchecked")
-  private static <K, V> Function<Map<K, V>, Map<K, V>> unmodifiableWrapper() {
+  private static <K extends @Nullable Object, V extends @Nullable Object>
+      Function<Map<K, V>, Map<K, V>> unmodifiableWrapper() {
     return (Function) UNMODIFIABLE_WRAPPER;
   }
 
@@ -678,11 +746,12 @@ public Map<Object, Object> apply(Map<Object, Object> input) {
    * @return a synchronized view of the specified table
    * @since 22.0
    */
-  public static <R, C, V> Table<R, C, V> synchronizedTable(Table<R, C, V> table) {
+  public static <R extends @Nullable Object, C extends @Nullable Object, V extends @Nullable Object>
+      Table<R, C, V> synchronizedTable(Table<R, C, V> table) {
     return Synchronized.table(table, null);
   }
 
-  static boolean equalsImpl(Table<?, ?, ?> table, @Nullable Object obj) {
+  static boolean equalsImpl(Table<?, ?, ?> table, @CheckForNull Object obj) {
     if (obj == table) {
       return true;
     } else if (obj instanceof Table) {
diff --git a/guava/src/com/google/common/collect/TopKSelector.java b/guava/src/com/google/common/collect/TopKSelector.java
index 107b51925a80..20b17fdef10e 100644
--- a/guava/src/com/google/common/collect/TopKSelector.java
+++ b/guava/src/com/google/common/collect/TopKSelector.java
@@ -18,6 +18,7 @@
 
 import static com.google.common.base.Preconditions.checkArgument;
 import static com.google.common.base.Preconditions.checkNotNull;
+import static com.google.common.collect.NullnessCasts.uncheckedCastNullableTToT;
 
 import com.google.common.annotations.GwtCompatible;
 import com.google.common.math.IntMath;
@@ -28,6 +29,7 @@
 import java.util.Iterator;
 import java.util.List;
 import java.util.stream.Stream;
+import javax.annotation.CheckForNull;
 import org.checkerframework.checker.nullness.qual.Nullable;
 
 /**
@@ -52,7 +54,9 @@
  * @author Louis Wasserman
  */
 @GwtCompatible
-final class TopKSelector<T> {
+@ElementTypesAreNonnullByDefault
+final class TopKSelector<
+    T extends @Nullable Object> {
 
   /**
    * Returns a {@code TopKSelector} that collects the lowest {@code k} elements added to it,
@@ -71,7 +75,8 @@ public static <T extends Comparable<? super T>> TopKSelector<T> least(int k) {
    *
    * @throws IllegalArgumentException if {@code k < 0} or {@code k > Integer.MAX_VALUE / 2}
    */
-  public static <T> TopKSelector<T> least(int k, Comparator<? super T> comparator) {
+  public static <T extends @Nullable Object> TopKSelector<T> least(
+      int k, Comparator<? super T> comparator) {
     return new TopKSelector<T>(comparator, k);
   }
 
@@ -92,7 +97,8 @@ public static <T extends Comparable<? super T>> TopKSelector<T> greatest(int k)
    *
    * @throws IllegalArgumentException if {@code k < 0} or {@code k > Integer.MAX_VALUE / 2}
    */
-  public static <T> TopKSelector<T> greatest(int k, Comparator<? super T> comparator) {
+  public static <T extends @Nullable Object> TopKSelector<T> greatest(
+      int k, Comparator<? super T> comparator) {
     return new TopKSelector<T>(Ordering.from(comparator).reverse(), k);
   }
 
@@ -104,14 +110,14 @@ public static <T> TopKSelector<T> greatest(int k, Comparator<? super T> comparat
    * for the top k elements. Whenever the buffer is filled, we quickselect the top k elements to the
    * range [0, k) and ignore the remaining elements.
    */
-  private final T[] buffer;
+  private final @Nullable T[] buffer;
   private int bufferSize;
 
   /**
    * The largest of the lowest k elements we've seen so far relative to this comparator. If
    * bufferSize ≥ k, then we can ignore any elements greater than this value.
    */
-  private @Nullable T threshold;
+  @CheckForNull private T threshold;
 
   private TopKSelector(Comparator<? super T> comparator, int k) {
     this.comparator = checkNotNull(comparator, "comparator");
@@ -127,7 +133,7 @@ private TopKSelector(Comparator<? super T> comparator, int k) {
    * Adds {@code elem} as a candidate for the top {@code k} elements. This operation takes amortized
    * O(1) time.
    */
-  public void offer(@Nullable T elem) {
+  public void offer(@ParametricNullness T elem) {
     if (k == 0) {
       return;
     } else if (bufferSize == 0) {
@@ -136,10 +142,12 @@ public void offer(@Nullable T elem) {
       bufferSize = 1;
     } else if (bufferSize < k) {
       buffer[bufferSize++] = elem;
-      if (comparator.compare(elem, threshold) > 0) {
+      // uncheckedCastNullableTToT is safe because bufferSize > 0.
+      if (comparator.compare(elem, uncheckedCastNullableTToT(threshold)) > 0) {
         threshold = elem;
       }
-    } else if (comparator.compare(elem, threshold) < 0) {
+      // uncheckedCastNullableTToT is safe because bufferSize > 0.
+    } else if (comparator.compare(elem, uncheckedCastNullableTToT(threshold)) < 0) {
       // Otherwise, we can ignore elem; we've seen k better elements.
       buffer[bufferSize++] = elem;
       if (bufferSize == 2 * k) {
@@ -177,16 +185,20 @@ private void trim() {
       }
       iterations++;
       if (iterations >= maxIterations) {
+        @SuppressWarnings("nullness") // safe because we pass sort() a range that contains real Ts
+        T[] castBuffer = (T[]) buffer;
         // We've already taken O(k log k), let's make sure we don't take longer than O(k log k).
-        Arrays.sort(buffer, left, right, comparator);
+        Arrays.sort(castBuffer, left, right + 1, comparator);
         break;
       }
     }
     bufferSize = k;
 
-    threshold = buffer[minThresholdPosition];
+    threshold = uncheckedCastNullableTToT(buffer[minThresholdPosition]);
     for (int i = minThresholdPosition + 1; i < k; i++) {
-      if (comparator.compare(buffer[i], threshold) > 0) {
+      if (comparator.compare(
+              uncheckedCastNullableTToT(buffer[i]), uncheckedCastNullableTToT(threshold))
+          > 0) {
         threshold = buffer[i];
       }
     }
@@ -199,12 +211,12 @@ private void trim() {
    * (pivotNewIndex, right] is greater than pivotValue.
    */
   private int partition(int left, int right, int pivotIndex) {
-    T pivotValue = buffer[pivotIndex];
+    T pivotValue = uncheckedCastNullableTToT(buffer[pivotIndex]);
     buffer[pivotIndex] = buffer[right];
 
     int pivotNewIndex = left;
     for (int i = left; i < right; i++) {
-      if (comparator.compare(buffer[i], pivotValue) < 0) {
+      if (comparator.compare(uncheckedCastNullableTToT(buffer[i]), pivotValue) < 0) {
         swap(pivotNewIndex, i);
         pivotNewIndex++;
       }
@@ -222,7 +234,7 @@ private void swap(int i, int j) {
 
   TopKSelector<T> combine(TopKSelector<T> other) {
     for (int i = 0; i < other.bufferSize; i++) {
-      this.offer(other.buffer[i]);
+      this.offer(uncheckedCastNullableTToT(other.buffer[i]));
     }
     return this;
   }
@@ -261,7 +273,9 @@ public void offerAll(Iterator<? extends T> elements) {
    * this {@code TopKSelector}. This method returns in O(k log k) time.
    */
   public List<T> topK() {
-    Arrays.sort(buffer, 0, bufferSize, comparator);
+    @SuppressWarnings("nullness") // safe because we pass sort() a range that contains real Ts
+    T[] castBuffer = (T[]) buffer;
+    Arrays.sort(castBuffer, 0, bufferSize, comparator);
     if (bufferSize > k) {
       Arrays.fill(buffer, k, buffer.length, null);
       bufferSize = k;
diff --git a/guava/src/com/google/common/collect/TransformedIterator.java b/guava/src/com/google/common/collect/TransformedIterator.java
index b7214b8abd75..2456cecde991 100644
--- a/guava/src/com/google/common/collect/TransformedIterator.java
+++ b/guava/src/com/google/common/collect/TransformedIterator.java
@@ -20,6 +20,7 @@
 
 import com.google.common.annotations.GwtCompatible;
 import java.util.Iterator;
+import org.checkerframework.checker.nullness.qual.Nullable;
 
 /**
  * An iterator that transforms a backing iterator; for internal use. This avoids the object overhead
@@ -28,14 +29,17 @@
  * @author Louis Wasserman
  */
 @GwtCompatible
-abstract class TransformedIterator<F, T> implements Iterator<T> {
+@ElementTypesAreNonnullByDefault
+abstract class TransformedIterator<F extends @Nullable Object, T extends @Nullable Object>
+    implements Iterator<T> {
   final Iterator<? extends F> backingIterator;
 
   TransformedIterator(Iterator<? extends F> backingIterator) {
     this.backingIterator = checkNotNull(backingIterator);
   }
 
-  abstract T transform(F from);
+  @ParametricNullness
+  abstract T transform(@ParametricNullness F from);
 
   @Override
   public final boolean hasNext() {
@@ -43,6 +47,7 @@ public final boolean hasNext() {
   }
 
   @Override
+  @ParametricNullness
   public final T next() {
     return transform(backingIterator.next());
   }
diff --git a/guava/src/com/google/common/collect/TransformedListIterator.java b/guava/src/com/google/common/collect/TransformedListIterator.java
index ac2eea1e1516..66b42e4c6048 100644
--- a/guava/src/com/google/common/collect/TransformedListIterator.java
+++ b/guava/src/com/google/common/collect/TransformedListIterator.java
@@ -19,6 +19,7 @@
 import com.google.common.annotations.GwtCompatible;
 import com.google.common.base.Function;
 import java.util.ListIterator;
+import org.checkerframework.checker.nullness.qual.Nullable;
 
 /**
  * An iterator that transforms a backing list iterator; for internal use. This avoids the object
@@ -27,8 +28,9 @@
  * @author Louis Wasserman
  */
 @GwtCompatible
-abstract class TransformedListIterator<F, T> extends TransformedIterator<F, T>
-    implements ListIterator<T> {
+@ElementTypesAreNonnullByDefault
+abstract class TransformedListIterator<F extends @Nullable Object, T extends @Nullable Object>
+    extends TransformedIterator<F, T> implements ListIterator<T> {
   TransformedListIterator(ListIterator<? extends F> backingIterator) {
     super(backingIterator);
   }
@@ -43,6 +45,7 @@ public final boolean hasPrevious() {
   }
 
   @Override
+  @ParametricNullness
   public final T previous() {
     return transform(backingIterator().previous());
   }
@@ -58,12 +61,12 @@ public final int previousIndex() {
   }
 
   @Override
-  public void set(T element) {
+  public void set(@ParametricNullness T element) {
     throw new UnsupportedOperationException();
   }
 
   @Override
-  public void add(T element) {
+  public void add(@ParametricNullness T element) {
     throw new UnsupportedOperationException();
   }
 }
diff --git a/guava/src/com/google/common/collect/TreeBasedTable.java b/guava/src/com/google/common/collect/TreeBasedTable.java
index 510f75c66b53..9ef210a54a62 100644
--- a/guava/src/com/google/common/collect/TreeBasedTable.java
+++ b/guava/src/com/google/common/collect/TreeBasedTable.java
@@ -18,9 +18,9 @@
 
 import static com.google.common.base.Preconditions.checkArgument;
 import static com.google.common.base.Preconditions.checkNotNull;
+import static java.util.Objects.requireNonNull;
 
 import com.google.common.annotations.GwtCompatible;
-import com.google.common.base.Function;
 import com.google.common.base.Supplier;
 import java.io.Serializable;
 import java.util.Comparator;
@@ -31,7 +31,7 @@
 import java.util.SortedMap;
 import java.util.SortedSet;
 import java.util.TreeMap;
-import org.checkerframework.checker.nullness.qual.Nullable;
+import javax.annotation.CheckForNull;
 
 /**
  * Implementation of {@code Table} whose row keys and column keys are ordered by their natural
@@ -59,13 +59,14 @@
  * concurrently and one of the threads modifies the table, it must be synchronized externally.
  *
  * <p>See the Guava User Guide article on <a href=
- * "https://github.com/google/guava/wiki/NewCollectionTypesExplained#table"> {@code Table}</a>.
+ * "https://github.com/google/guava/wiki/NewCollectionTypesExplained#table">{@code Table}</a>.
  *
  * @author Jared Levy
  * @author Louis Wasserman
  * @since 7.0
  */
 @GwtCompatible(serializable = true)
+@ElementTypesAreNonnullByDefault
 public class TreeBasedTable<R, C, V> extends StandardRowSortedTable<R, C, V> {
   private final Comparator<? super C> columnComparator;
 
@@ -135,7 +136,11 @@ public static <R, C, V> TreeBasedTable<R, C, V> create(TreeBasedTable<R, C, ? ex
    */
   @Deprecated
   public Comparator<? super R> rowComparator() {
-    return rowKeySet().comparator();
+    /*
+     * requireNonNull is safe because the factories require non-null Comparators, which they pass on
+     * to the backing collections.
+     */
+    return requireNonNull(rowKeySet().comparator());
   }
 
   /**
@@ -169,14 +174,14 @@ public SortedMap<C, V> row(R rowKey) {
   }
 
   private class TreeRow extends Row implements SortedMap<C, V> {
-    final @Nullable C lowerBound;
-    final @Nullable C upperBound;
+    @CheckForNull final C lowerBound;
+    @CheckForNull final C upperBound;
 
     TreeRow(R rowKey) {
       this(rowKey, null, null);
     }
 
-    TreeRow(R rowKey, @Nullable C lowerBound, @Nullable C upperBound) {
+    TreeRow(R rowKey, @CheckForNull C lowerBound, @CheckForNull C upperBound) {
       super(rowKey);
       this.lowerBound = lowerBound;
       this.upperBound = upperBound;
@@ -201,7 +206,7 @@ int compare(Object a, Object b) {
       return cmp.compare(a, b);
     }
 
-    boolean rangeContains(@Nullable Object o) {
+    boolean rangeContains(@CheckForNull Object o) {
       return o != null
           && (lowerBound == null || compare(lowerBound, o) <= 0)
           && (upperBound == null || compare(upperBound, o) > 0);
@@ -227,43 +232,36 @@ public SortedMap<C, V> tailMap(C fromKey) {
 
     @Override
     public C firstKey() {
-      SortedMap<C, V> backing = backingRowMap();
-      if (backing == null) {
+      updateBackingRowMapField();
+      if (backingRowMap == null) {
         throw new NoSuchElementException();
       }
-      return backingRowMap().firstKey();
+      return ((SortedMap<C, V>) backingRowMap).firstKey();
     }
 
     @Override
     public C lastKey() {
-      SortedMap<C, V> backing = backingRowMap();
-      if (backing == null) {
+      updateBackingRowMapField();
+      if (backingRowMap == null) {
         throw new NoSuchElementException();
       }
-      return backingRowMap().lastKey();
+      return ((SortedMap<C, V>) backingRowMap).lastKey();
     }
 
-    transient @Nullable SortedMap<C, V> wholeRow;
+    @CheckForNull transient SortedMap<C, V> wholeRow;
 
-    /*
-     * If the row was previously empty, we check if there's a new row here every
-     * time we're queried.
-     */
-    SortedMap<C, V> wholeRow() {
+    // If the row was previously empty, we check if there's a new row here every time we're queried.
+    void updateWholeRowField() {
       if (wholeRow == null || (wholeRow.isEmpty() && backingMap.containsKey(rowKey))) {
         wholeRow = (SortedMap<C, V>) backingMap.get(rowKey);
       }
-      return wholeRow;
-    }
-
-    @Override
-    SortedMap<C, V> backingRowMap() {
-      return (SortedMap<C, V>) super.backingRowMap();
     }
 
     @Override
+    @CheckForNull
     SortedMap<C, V> computeBackingRowMap() {
-      SortedMap<C, V> map = wholeRow();
+      updateWholeRowField();
+      SortedMap<C, V> map = wholeRow;
       if (map != null) {
         if (lowerBound != null) {
           map = map.tailMap(lowerBound);
@@ -278,7 +276,8 @@ SortedMap<C, V> computeBackingRowMap() {
 
     @Override
     void maintainEmptyInvariant() {
-      if (wholeRow() != null && wholeRow.isEmpty()) {
+      updateWholeRowField();
+      if (wholeRow != null && wholeRow.isEmpty()) {
         backingMap.remove(rowKey);
         wholeRow = null;
         backingRowMap = null;
@@ -286,11 +285,12 @@ void maintainEmptyInvariant() {
     }
 
     @Override
-    public boolean containsKey(Object key) {
+    public boolean containsKey(@CheckForNull Object key) {
       return rangeContains(key) && super.containsKey(key);
     }
 
     @Override
+    @CheckForNull
     public V put(C key, V value) {
       checkArgument(rangeContains(checkNotNull(key)));
       return super.put(key, value);
@@ -312,24 +312,19 @@ public SortedMap<R, Map<C, V>> rowMap() {
   /** Overridden column iterator to return columns values in globally sorted order. */
   @Override
   Iterator<C> createColumnKeyIterator() {
-    final Comparator<? super C> comparator = columnComparator();
+    Comparator<? super C> comparator = columnComparator();
 
-    final Iterator<C> merged =
+    Iterator<C> merged =
         Iterators.mergeSorted(
             Iterables.transform(
-                backingMap.values(),
-                new Function<Map<C, V>, Iterator<C>>() {
-                  @Override
-                  public Iterator<C> apply(Map<C, V> input) {
-                    return input.keySet().iterator();
-                  }
-                }),
+                backingMap.values(), (Map<C, V> input) -> input.keySet().iterator()),
             comparator);
 
     return new AbstractIterator<C>() {
-      @Nullable C lastValue;
+      @CheckForNull C lastValue;
 
       @Override
+      @CheckForNull
       protected C computeNext() {
         while (merged.hasNext()) {
           C next = merged.next();
diff --git a/guava/src/com/google/common/collect/TreeMultimap.java b/guava/src/com/google/common/collect/TreeMultimap.java
index e847a12d4f26..b8b9d5d26888 100644
--- a/guava/src/com/google/common/collect/TreeMultimap.java
+++ b/guava/src/com/google/common/collect/TreeMultimap.java
@@ -67,8 +67,7 @@
  * with a call to {@link Multimaps#synchronizedSortedSetMultimap}.
  *
  * <p>See the Guava User Guide article on <a href=
- * "https://github.com/google/guava/wiki/NewCollectionTypesExplained#multimap"> {@code
- * Multimap}</a>.
+ * "https://github.com/google/guava/wiki/NewCollectionTypesExplained#multimap">{@code Multimap}</a>.
  *
  * @author Jared Levy
  * @author Louis Wasserman
@@ -76,9 +75,11 @@
  */
 @AnnotatedFor({"nullness"})
 @GwtCompatible(serializable = true, emulated = true)
-public class TreeMultimap<K, V> extends AbstractSortedKeySortedSetMultimap<K, V> {
-  private transient @Nullable Comparator<? super K> keyComparator;
-  private transient @Nullable Comparator<? super V> valueComparator;
+@ElementTypesAreNonnullByDefault
+public class TreeMultimap<K extends @Nullable Object, V extends @Nullable Object>
+    extends AbstractSortedKeySortedSetMultimap<K, V> {
+  private transient Comparator<? super K> keyComparator;
+  private transient Comparator<? super V> valueComparator;
 
   /**
    * Creates an empty {@code TreeMultimap} ordered by the natural ordering of its keys and values.
@@ -94,7 +95,7 @@ public static <K extends Comparable, V extends Comparable> TreeMultimap<K, V> cr
    * @param keyComparator the comparator that determines the key ordering
    * @param valueComparator the comparator that determines the value ordering
    */
-  public static <K, V> TreeMultimap<K, V> create(
+  public static <K extends @Nullable Object, V extends @Nullable Object> TreeMultimap<K, V> create(
       Comparator<? super K> keyComparator, Comparator<? super V> valueComparator) {
     return new TreeMultimap<>(checkNotNull(keyComparator), checkNotNull(valueComparator));
   }
@@ -138,11 +139,11 @@ Map<K, Collection<V>> createAsMap() {
    */
   @Override
   SortedSet<V> createCollection() {
-    return new TreeSet<V>(valueComparator);
+    return new TreeSet<>(valueComparator);
   }
 
   @Override
-  Collection<V> createCollection(@Nullable K key) {
+  Collection<V> createCollection(@ParametricNullness K key) {
     if (key == null) {
       keyComparator().compare(key, key);
     }
@@ -167,7 +168,7 @@ Collection<V> createCollection(@Nullable K key) {
   /** @since 14.0 (present with return type {@code SortedSet} since 2.0) */
   @Override
   @GwtIncompatible // NavigableSet
-  public NavigableSet<V> get(@Nullable K key) {
+  public NavigableSet<V> get(@ParametricNullness K key) {
     return (NavigableSet<V>) super.get(key);
   }
 
diff --git a/guava/src/com/google/common/collect/TreeMultiset.java b/guava/src/com/google/common/collect/TreeMultiset.java
index 299756666753..cd5e1d6c1921 100644
--- a/guava/src/com/google/common/collect/TreeMultiset.java
+++ b/guava/src/com/google/common/collect/TreeMultiset.java
@@ -20,7 +20,8 @@
 import static com.google.common.base.Preconditions.checkNotNull;
 import static com.google.common.base.Preconditions.checkState;
 import static com.google.common.collect.CollectPreconditions.checkNonnegative;
-import static com.google.common.collect.CollectPreconditions.checkRemove;
+import static com.google.common.collect.NullnessCasts.uncheckedCastNullableTToT;
+import static java.util.Objects.requireNonNull;
 
 import com.google.common.annotations.GwtCompatible;
 import com.google.common.annotations.GwtIncompatible;
@@ -37,6 +38,7 @@
 import java.util.Iterator;
 import java.util.NoSuchElementException;
 import java.util.function.ObjIntConsumer;
+import javax.annotation.CheckForNull;
 import org.checkerframework.checker.nullness.qual.Nullable;
 import org.checkerframework.dataflow.qual.Pure;
 import org.checkerframework.framework.qual.AnnotatedFor;
@@ -52,8 +54,7 @@
  * java.util.Collection} contract, which is specified in terms of {@link Object#equals}.
  *
  * <p>See the Guava User Guide article on <a href=
- * "https://github.com/google/guava/wiki/NewCollectionTypesExplained#multiset"> {@code
- * Multiset}</a>.
+ * "https://github.com/google/guava/wiki/NewCollectionTypesExplained#multiset">{@code Multiset}</a>.
  *
  * @author Louis Wasserman
  * @author Jared Levy
@@ -61,7 +62,9 @@
  */
 @AnnotatedFor({"nullness"})
 @GwtCompatible(emulated = true)
-public final class TreeMultiset<E> extends AbstractSortedMultiset<E> implements Serializable {
+@ElementTypesAreNonnullByDefault
+public final class TreeMultiset<E extends @Nullable Object> extends AbstractSortedMultiset<E>
+    implements Serializable {
 
   /**
    * Creates a new, empty multiset, sorted according to the elements' natural order. All elements
@@ -91,7 +94,8 @@ public static <E extends Comparable> TreeMultiset<E> create() {
    *     indicates that the elements' <i>natural ordering</i> should be used.
    */
   @SuppressWarnings("unchecked")
-  public static <E> TreeMultiset<E> create(@Nullable Comparator<? super E> comparator) {
+  public static <E extends @Nullable Object> TreeMultiset<E> create(
+      @CheckForNull Comparator<? super E> comparator) {
     return (comparator == null)
         ? new TreeMultiset<E>((Comparator) Ordering.natural())
         : new TreeMultiset<E>(comparator);
@@ -126,7 +130,7 @@ public static <E extends Comparable> TreeMultiset<E> create(Iterable<? extends E
   TreeMultiset(Comparator<? super E> comparator) {
     super(comparator);
     this.range = GeneralRange.all(comparator);
-    this.header = new AvlNode<E>(null, 1);
+    this.header = new AvlNode<>();
     successor(header, header);
     this.rootReference = new Reference<>();
   }
@@ -140,7 +144,7 @@ int nodeAggregate(AvlNode<?> node) {
       }
 
       @Override
-      long treeAggregate(@Nullable AvlNode<?> root) {
+      long treeAggregate(@CheckForNull AvlNode<?> root) {
         return (root == null) ? 0 : root.totalCount;
       }
     },
@@ -151,14 +155,14 @@ int nodeAggregate(AvlNode<?> node) {
       }
 
       @Override
-      long treeAggregate(@Nullable AvlNode<?> root) {
+      long treeAggregate(@CheckForNull AvlNode<?> root) {
         return (root == null) ? 0 : root.distinctElements;
       }
     };
 
     abstract int nodeAggregate(AvlNode<?> node);
 
-    abstract long treeAggregate(@Nullable AvlNode<?> root);
+    abstract long treeAggregate(@CheckForNull AvlNode<?> root);
   }
 
   private long aggregateForEntries(Aggregate aggr) {
@@ -173,11 +177,14 @@ private long aggregateForEntries(Aggregate aggr) {
     return total;
   }
 
-  private long aggregateBelowRange(Aggregate aggr, @Nullable AvlNode<E> node) {
+  private long aggregateBelowRange(Aggregate aggr, @CheckForNull AvlNode<E> node) {
     if (node == null) {
       return 0;
     }
-    int cmp = comparator().compare(range.getLowerEndpoint(), node.elem);
+    // The cast is safe because we call this method only if hasLowerBound().
+    int cmp =
+        comparator()
+            .compare(uncheckedCastNullableTToT(range.getLowerEndpoint()), node.getElement());
     if (cmp < 0) {
       return aggregateBelowRange(aggr, node.left);
     } else if (cmp == 0) {
@@ -196,11 +203,14 @@ private long aggregateBelowRange(Aggregate aggr, @Nullable AvlNode<E> node) {
     }
   }
 
-  private long aggregateAboveRange(Aggregate aggr, @Nullable AvlNode<E> node) {
+  private long aggregateAboveRange(Aggregate aggr, @CheckForNull AvlNode<E> node) {
     if (node == null) {
       return 0;
     }
-    int cmp = comparator().compare(range.getUpperEndpoint(), node.elem);
+    // The cast is safe because we call this method only if hasUpperBound().
+    int cmp =
+        comparator()
+            .compare(uncheckedCastNullableTToT(range.getUpperEndpoint()), node.getElement());
     if (cmp > 0) {
       return aggregateAboveRange(aggr, node.right);
     } else if (cmp == 0) {
@@ -230,12 +240,12 @@ int distinctElements() {
     return Ints.saturatedCast(aggregateForEntries(Aggregate.DISTINCT));
   }
 
-  static int distinctElements(@Nullable AvlNode<?> node) {
+  static int distinctElements(@CheckForNull AvlNode<?> node) {
     return (node == null) ? 0 : node.distinctElements;
   }
 
   @Override
-  public int count(@Nullable Object element) {
+  public int count(@CheckForNull Object element) {
     try {
       @SuppressWarnings("unchecked")
       E e = (E) element;
@@ -251,7 +261,7 @@ public int count(@Nullable Object element) {
 
   @CanIgnoreReturnValue
   @Override
-  public int add(@Nullable E element, int occurrences) {
+  public int add(@ParametricNullness E element, int occurrences) {
     checkNonnegative(occurrences, "occurrences");
     if (occurrences == 0) {
       return count(element);
@@ -273,7 +283,7 @@ public int add(@Nullable E element, int occurrences) {
 
   @CanIgnoreReturnValue
   @Override
-  public int remove(@Nullable Object element, int occurrences) {
+  public int remove(@CheckForNull Object element, int occurrences) {
     checkNonnegative(occurrences, "occurrences");
     if (occurrences == 0) {
       return count(element);
@@ -297,7 +307,7 @@ public int remove(@Nullable Object element, int occurrences) {
 
   @CanIgnoreReturnValue
   @Override
-  public int setCount(@Nullable E element, int count) {
+  public int setCount(@ParametricNullness E element, int count) {
     checkNonnegative(count, "count");
     if (!range.contains(element)) {
       checkArgument(count == 0);
@@ -319,7 +329,7 @@ public int setCount(@Nullable E element, int count) {
 
   @CanIgnoreReturnValue
   @Override
-  public boolean setCount(@Nullable E element, int oldCount, int newCount) {
+  public boolean setCount(@ParametricNullness E element, int oldCount, int newCount) {
     checkNonnegative(newCount, "newCount");
     checkNonnegative(oldCount, "oldCount");
     checkArgument(range.contains(element));
@@ -345,8 +355,8 @@ public boolean setCount(@Nullable E element, int oldCount, int newCount) {
   public void clear() {
     if (!range.hasLowerBound() && !range.hasUpperBound()) {
       // We can do this in O(n) rather than removing one by one, which could force rebalancing.
-      for (AvlNode<E> current = header.succ; current != header; ) {
-        AvlNode<E> next = current.succ;
+      for (AvlNode<E> current = header.succ(); current != header; ) {
+        AvlNode<E> next = current.succ();
 
         current.elemCount = 0;
         // Also clear these fields so that one deleted Entry doesn't retain all elements.
@@ -368,6 +378,7 @@ public void clear() {
   private Entry<E> wrapEntry(final AvlNode<E> baseEntry) {
     return new Multisets.AbstractEntry<E>() {
       @Override
+      @ParametricNullness
       public E getElement() {
         return baseEntry.getElement();
       }
@@ -385,46 +396,50 @@ public int getCount() {
   }
 
   /** Returns the first node in the tree that is in range. */
-  private @Nullable AvlNode<E> firstNode() {
+  @CheckForNull
+  private AvlNode<E> firstNode() {
     AvlNode<E> root = rootReference.get();
     if (root == null) {
       return null;
     }
     AvlNode<E> node;
     if (range.hasLowerBound()) {
-      E endpoint = range.getLowerEndpoint();
-      node = rootReference.get().ceiling(comparator(), endpoint);
+      // The cast is safe because of the hasLowerBound check.
+      E endpoint = uncheckedCastNullableTToT(range.getLowerEndpoint());
+      node = root.ceiling(comparator(), endpoint);
       if (node == null) {
         return null;
       }
       if (range.getLowerBoundType() == BoundType.OPEN
           && comparator().compare(endpoint, node.getElement()) == 0) {
-        node = node.succ;
+        node = node.succ();
       }
     } else {
-      node = header.succ;
+      node = header.succ();
     }
     return (node == header || !range.contains(node.getElement())) ? null : node;
   }
 
-  private @Nullable AvlNode<E> lastNode() {
+  @CheckForNull
+  private AvlNode<E> lastNode() {
     AvlNode<E> root = rootReference.get();
     if (root == null) {
       return null;
     }
     AvlNode<E> node;
     if (range.hasUpperBound()) {
-      E endpoint = range.getUpperEndpoint();
-      node = rootReference.get().floor(comparator(), endpoint);
+      // The cast is safe because of the hasUpperBound check.
+      E endpoint = uncheckedCastNullableTToT(range.getUpperEndpoint());
+      node = root.floor(comparator(), endpoint);
       if (node == null) {
         return null;
       }
       if (range.getUpperBoundType() == BoundType.OPEN
           && comparator().compare(endpoint, node.getElement()) == 0) {
-        node = node.pred;
+        node = node.pred();
       }
     } else {
-      node = header.pred;
+      node = header.pred();
     }
     return (node == header || !range.contains(node.getElement())) ? null : node;
   }
@@ -437,8 +452,8 @@ Iterator<E> elementIterator() {
   @Override
   Iterator<Entry<E>> entryIterator() {
     return new Iterator<Entry<E>>() {
-      AvlNode<E> current = firstNode();
-      @Nullable Entry<E> prevEntry;
+      @CheckForNull AvlNode<E> current = firstNode();
+      @CheckForNull Entry<E> prevEntry;
 
       @Override
       public boolean hasNext() {
@@ -457,19 +472,20 @@ public Entry<E> next() {
         if (!hasNext()) {
           throw new NoSuchElementException();
         }
-        Entry<E> result = wrapEntry(current);
+        // requireNonNull is safe because current is only nulled out after iteration is complete.
+        Entry<E> result = wrapEntry(requireNonNull(current));
         prevEntry = result;
-        if (current.succ == header) {
+        if (current.succ() == header) {
           current = null;
         } else {
-          current = current.succ;
+          current = current.succ();
         }
         return result;
       }
 
       @Override
       public void remove() {
-        checkRemove(prevEntry != null);
+        checkState(prevEntry != null, "no calls to next() since the last call to remove()");
         setCount(prevEntry.getElement(), 0);
         prevEntry = null;
       }
@@ -479,8 +495,8 @@ public void remove() {
   @Override
   Iterator<Entry<E>> descendingEntryIterator() {
     return new Iterator<Entry<E>>() {
-      AvlNode<E> current = lastNode();
-      Entry<E> prevEntry = null;
+      @CheckForNull AvlNode<E> current = lastNode();
+      @CheckForNull Entry<E> prevEntry = null;
 
       @Override
       public boolean hasNext() {
@@ -499,19 +515,21 @@ public Entry<E> next() {
         if (!hasNext()) {
           throw new NoSuchElementException();
         }
+        // requireNonNull is safe because current is only nulled out after iteration is complete.
+        requireNonNull(current);
         Entry<E> result = wrapEntry(current);
         prevEntry = result;
-        if (current.pred == header) {
+        if (current.pred() == header) {
           current = null;
         } else {
-          current = current.pred;
+          current = current.pred();
         }
         return result;
       }
 
       @Override
       public void remove() {
-        checkRemove(prevEntry != null);
+        checkState(prevEntry != null, "no calls to next() since the last call to remove()");
         setCount(prevEntry.getElement(), 0);
         prevEntry = null;
       }
@@ -523,7 +541,7 @@ public void forEachEntry(ObjIntConsumer<? super E> action) {
     checkNotNull(action);
     for (AvlNode<E> node = firstNode();
         node != header && node != null && !range.tooHigh(node.getElement());
-        node = node.succ) {
+        node = node.succ()) {
       action.accept(node.getElement(), node.getCount());
     }
   }
@@ -534,7 +552,7 @@ public Iterator<E> iterator() {
   }
 
   @Override
-  public SortedMultiset<E> headMultiset(@Nullable E upperBound, BoundType boundType) {
+  public SortedMultiset<E> headMultiset(@ParametricNullness E upperBound, BoundType boundType) {
     return new TreeMultiset<E>(
         rootReference,
         range.intersect(GeneralRange.upTo(comparator(), upperBound, boundType)),
@@ -542,7 +560,7 @@ public SortedMultiset<E> headMultiset(@Nullable E upperBound, BoundType boundTyp
   }
 
   @Override
-  public SortedMultiset<E> tailMultiset(@Nullable E lowerBound, BoundType boundType) {
+  public SortedMultiset<E> tailMultiset(@ParametricNullness E lowerBound, BoundType boundType) {
     return new TreeMultiset<E>(
         rootReference,
         range.intersect(GeneralRange.downTo(comparator(), lowerBound, boundType)),
@@ -550,13 +568,14 @@ public SortedMultiset<E> tailMultiset(@Nullable E lowerBound, BoundType boundTyp
   }
 
   private static final class Reference<T> {
-    private @Nullable T value;
+    @CheckForNull private T value;
 
-    public @Nullable T get() {
+    @CheckForNull
+    public T get() {
       return value;
     }
 
-    public void checkAndSet(@Nullable T expected, T newValue) {
+    public void checkAndSet(@CheckForNull T expected, @CheckForNull T newValue) {
       if (value != expected) {
         throw new ConcurrentModificationException();
       }
@@ -568,8 +587,18 @@ void clear() {
     }
   }
 
-  private static final class AvlNode<E> {
-    private final @Nullable E elem;
+  private static final class AvlNode<E extends @Nullable Object> {
+    /*
+     * For "normal" nodes, the type of this field is `E`, not `@Nullable E` (though note that E is a
+     * type that can include null, as in a TreeMultiset<@Nullable String>).
+     *
+     * For the header node, though, this field contains `null`, regardless of the type of the
+     * multiset.
+     *
+     * Most code that operates on an AvlNode never operates on the header node. Such code can access
+     * the elem field without a null check by calling getElement().
+     */
+    @CheckForNull private final E elem;
 
     // elemCount is 0 iff this node has been deleted.
     private int elemCount;
@@ -577,12 +606,23 @@ private static final class AvlNode<E> {
     private int distinctElements;
     private long totalCount;
     private int height;
-    private @Nullable AvlNode<E> left;
-    private @Nullable AvlNode<E> right;
-    private @Nullable AvlNode<E> pred;
-    private @Nullable AvlNode<E> succ;
-
-    AvlNode(@Nullable E elem, int elemCount) {
+    @CheckForNull private AvlNode<E> left;
+    @CheckForNull private AvlNode<E> right;
+    /*
+     * pred and succ are nullable after construction, but we always call successor() to initialize
+     * them immediately thereafter.
+     *
+     * They may be subsequently nulled out by TreeMultiset.clear(). I think that the only place that
+     * we can reference a node whose fields have been cleared is inside the iterator (and presumably
+     * only under concurrent modification).
+     *
+     * To access these fields when you know that they are not null, call the pred() and succ()
+     * methods, which perform null checks before returning the fields.
+     */
+    @CheckForNull private AvlNode<E> pred;
+    @CheckForNull private AvlNode<E> succ;
+
+    AvlNode(@ParametricNullness E elem, int elemCount) {
       checkArgument(elemCount > 0);
       this.elem = elem;
       this.elemCount = elemCount;
@@ -593,8 +633,24 @@ private static final class AvlNode<E> {
       this.right = null;
     }
 
-    public int count(Comparator<? super E> comparator, E e) {
-      int cmp = comparator.compare(e, elem);
+    /** Constructor for the header node. */
+    AvlNode() {
+      this.elem = null;
+      this.elemCount = 1;
+    }
+
+    // For discussion of pred() and succ(), see the comment on the pred and succ fields.
+
+    private AvlNode<E> pred() {
+      return requireNonNull(pred);
+    }
+
+    private AvlNode<E> succ() {
+      return requireNonNull(succ);
+    }
+
+    int count(Comparator<? super E> comparator, @ParametricNullness E e) {
+      int cmp = comparator.compare(e, getElement());
       if (cmp < 0) {
         return (left == null) ? 0 : left.count(comparator, e);
       } else if (cmp > 0) {
@@ -604,30 +660,31 @@ public int count(Comparator<? super E> comparator, E e) {
       }
     }
 
-    private AvlNode<E> addRightChild(E e, int count) {
+    private AvlNode<E> addRightChild(@ParametricNullness E e, int count) {
       right = new AvlNode<E>(e, count);
-      successor(this, right, succ);
+      successor(this, right, succ());
       height = Math.max(2, height);
       distinctElements++;
       totalCount += count;
       return this;
     }
 
-    private AvlNode<E> addLeftChild(E e, int count) {
+    private AvlNode<E> addLeftChild(@ParametricNullness E e, int count) {
       left = new AvlNode<E>(e, count);
-      successor(pred, left, this);
+      successor(pred(), left, this);
       height = Math.max(2, height);
       distinctElements++;
       totalCount += count;
       return this;
     }
 
-    AvlNode<E> add(Comparator<? super E> comparator, @Nullable E e, int count, int[] result) {
+    AvlNode<E> add(
+        Comparator<? super E> comparator, @ParametricNullness E e, int count, int[] result) {
       /*
        * It speeds things up considerably to unconditionally add count to totalCount here,
        * but that destroys failure atomicity in the case of count overflow. =(
        */
-      int cmp = comparator.compare(e, elem);
+      int cmp = comparator.compare(e, getElement());
       if (cmp < 0) {
         AvlNode<E> initLeft = left;
         if (initLeft == null) {
@@ -667,8 +724,10 @@ AvlNode<E> add(Comparator<? super E> comparator, @Nullable E e, int count, int[]
       return this;
     }
 
-    AvlNode<E> remove(Comparator<? super E> comparator, @Nullable E e, int count, int[] result) {
-      int cmp = comparator.compare(e, elem);
+    @CheckForNull
+    AvlNode<E> remove(
+        Comparator<? super E> comparator, @ParametricNullness E e, int count, int[] result) {
+      int cmp = comparator.compare(e, getElement());
       if (cmp < 0) {
         AvlNode<E> initLeft = left;
         if (initLeft == null) {
@@ -718,8 +777,10 @@ AvlNode<E> remove(Comparator<? super E> comparator, @Nullable E e, int count, in
       }
     }
 
-    AvlNode<E> setCount(Comparator<? super E> comparator, @Nullable E e, int count, int[] result) {
-      int cmp = comparator.compare(e, elem);
+    @CheckForNull
+    AvlNode<E> setCount(
+        Comparator<? super E> comparator, @ParametricNullness E e, int count, int[] result) {
+      int cmp = comparator.compare(e, getElement());
       if (cmp < 0) {
         AvlNode<E> initLeft = left;
         if (initLeft == null) {
@@ -766,13 +827,14 @@ AvlNode<E> setCount(Comparator<? super E> comparator, @Nullable E e, int count,
       return this;
     }
 
+    @CheckForNull
     AvlNode<E> setCount(
         Comparator<? super E> comparator,
-        @Nullable E e,
+        @ParametricNullness E e,
         int expectedCount,
         int newCount,
         int[] result) {
-      int cmp = comparator.compare(e, elem);
+      int cmp = comparator.compare(e, getElement());
       if (cmp < 0) {
         AvlNode<E> initLeft = left;
         if (initLeft == null) {
@@ -829,16 +891,17 @@ AvlNode<E> setCount(
       return this;
     }
 
+    @CheckForNull
     private AvlNode<E> deleteMe() {
       int oldElemCount = this.elemCount;
       this.elemCount = 0;
-      successor(pred, succ);
+      successor(pred(), succ());
       if (left == null) {
         return right;
       } else if (right == null) {
         return left;
       } else if (left.height >= right.height) {
-        AvlNode<E> newTop = pred;
+        AvlNode<E> newTop = pred();
         // newTop is the maximum node in my left subtree
         newTop.left = left.removeMax(newTop);
         newTop.right = right;
@@ -846,7 +909,7 @@ private AvlNode<E> deleteMe() {
         newTop.totalCount = totalCount - oldElemCount;
         return newTop.rebalance();
       } else {
-        AvlNode<E> newTop = succ;
+        AvlNode<E> newTop = succ();
         newTop.right = right.removeMin(newTop);
         newTop.left = left;
         newTop.distinctElements = distinctElements - 1;
@@ -856,6 +919,7 @@ private AvlNode<E> deleteMe() {
     }
 
     // Removes the minimum node from this subtree to be reused elsewhere
+    @CheckForNull
     private AvlNode<E> removeMin(AvlNode<E> node) {
       if (left == null) {
         return right;
@@ -868,6 +932,7 @@ private AvlNode<E> removeMin(AvlNode<E> node) {
     }
 
     // Removes the maximum node from this subtree to be reused elsewhere
+    @CheckForNull
     private AvlNode<E> removeMax(AvlNode<E> node) {
       if (right == null) {
         return left;
@@ -897,11 +962,15 @@ private void recompute() {
     private AvlNode<E> rebalance() {
       switch (balanceFactor()) {
         case -2:
+          // requireNonNull is safe because right must exist in order to get a negative factor.
+          requireNonNull(right);
           if (right.balanceFactor() > 0) {
             right = right.rotateRight();
           }
           return rotateLeft();
         case 2:
+          // requireNonNull is safe because left must exist in order to get a positive factor.
+          requireNonNull(left);
           if (left.balanceFactor() < 0) {
             left = left.rotateLeft();
           }
@@ -940,16 +1009,17 @@ private AvlNode<E> rotateRight() {
       return newTop;
     }
 
-    private static long totalCount(@Nullable AvlNode<?> node) {
+    private static long totalCount(@CheckForNull AvlNode<?> node) {
       return (node == null) ? 0 : node.totalCount;
     }
 
-    private static int height(@Nullable AvlNode<?> node) {
+    private static int height(@CheckForNull AvlNode<?> node) {
       return (node == null) ? 0 : node.height;
     }
 
-    private @Nullable AvlNode<E> ceiling(Comparator<? super E> comparator, E e) {
-      int cmp = comparator.compare(e, elem);
+    @CheckForNull
+    private AvlNode<E> ceiling(Comparator<? super E> comparator, @ParametricNullness E e) {
+      int cmp = comparator.compare(e, getElement());
       if (cmp < 0) {
         return (left == null) ? this : MoreObjects.firstNonNull(left.ceiling(comparator, e), this);
       } else if (cmp == 0) {
@@ -959,8 +1029,9 @@ private static int height(@Nullable AvlNode<?> node) {
       }
     }
 
-    private @Nullable AvlNode<E> floor(Comparator<? super E> comparator, E e) {
-      int cmp = comparator.compare(e, elem);
+    @CheckForNull
+    private AvlNode<E> floor(Comparator<? super E> comparator, @ParametricNullness E e) {
+      int cmp = comparator.compare(e, getElement());
       if (cmp > 0) {
         return (right == null) ? this : MoreObjects.firstNonNull(right.floor(comparator, e), this);
       } else if (cmp == 0) {
@@ -970,8 +1041,10 @@ private static int height(@Nullable AvlNode<?> node) {
       }
     }
 
+    @ParametricNullness
     E getElement() {
-      return elem;
+      // For discussion of this cast, see the comment on the elem field.
+      return uncheckedCastNullableTToT(elem);
     }
 
     int getCount() {
@@ -984,12 +1057,13 @@ public String toString() {
     }
   }
 
-  private static <T> void successor(AvlNode<T> a, AvlNode<T> b) {
+  private static <T extends @Nullable Object> void successor(AvlNode<T> a, AvlNode<T> b) {
     a.succ = b;
     b.pred = a;
   }
 
-  private static <T> void successor(AvlNode<T> a, AvlNode<T> b, AvlNode<T> c) {
+  private static <T extends @Nullable Object> void successor(
+      AvlNode<T> a, AvlNode<T> b, AvlNode<T> c) {
     successor(a, b);
     successor(b, c);
   }
@@ -1022,7 +1096,7 @@ private void readObject(ObjectInputStream stream) throws IOException, ClassNotFo
         .set(this, GeneralRange.all(comparator));
     Serialization.getFieldSetter(TreeMultiset.class, "rootReference")
         .set(this, new Reference<AvlNode<E>>());
-    AvlNode<E> header = new AvlNode<E>(null, 1);
+    AvlNode<E> header = new AvlNode<>();
     Serialization.getFieldSetter(TreeMultiset.class, "header").set(this, header);
     successor(header, header);
     Serialization.populateMultiset(this, stream);
diff --git a/guava/src/com/google/common/collect/TreeRangeMap.java b/guava/src/com/google/common/collect/TreeRangeMap.java
index 69491d4bb741..60e7bf3df874 100644
--- a/guava/src/com/google/common/collect/TreeRangeMap.java
+++ b/guava/src/com/google/common/collect/TreeRangeMap.java
@@ -21,6 +21,7 @@
 import static com.google.common.base.Predicates.compose;
 import static com.google.common.base.Predicates.in;
 import static com.google.common.base.Predicates.not;
+import static java.util.Objects.requireNonNull;
 
 import com.google.common.annotations.Beta;
 import com.google.common.annotations.GwtIncompatible;
@@ -38,6 +39,7 @@
 import java.util.NoSuchElementException;
 import java.util.Set;
 import java.util.function.BiFunction;
+import javax.annotation.CheckForNull;
 import org.checkerframework.checker.nullness.qual.Nullable;
 
 /**
@@ -51,6 +53,7 @@
  */
 @Beta
 @GwtIncompatible // NavigableMap
+@ElementTypesAreNonnullByDefault
 public final class TreeRangeMap<K extends Comparable, V> implements RangeMap<K, V> {
 
   private final NavigableMap<Cut<K>, RangeMapEntry<K, V>> entriesByLowerBound;
@@ -101,13 +104,15 @@ Cut<K> getUpperBound() {
   }
 
   @Override
-  public @Nullable V get(K key) {
+  @CheckForNull
+  public V get(K key) {
     Entry<Range<K>, V> entry = getEntry(key);
     return (entry == null) ? null : entry.getValue();
   }
 
   @Override
-  public @Nullable Entry<Range<K>, V> getEntry(K key) {
+  @CheckForNull
+  public Entry<Range<K>, V> getEntry(K key) {
     Entry<Cut<K>, RangeMapEntry<K, V>> mapEntry =
         entriesByLowerBound.floorEntry(Cut.belowValue(key));
     if (mapEntry != null && mapEntry.getValue().contains(key)) {
@@ -154,7 +159,7 @@ private Range<K> coalescedRange(Range<K> range, V value) {
 
   /** Returns the range that spans the given range and entry, if the entry can be coalesced. */
   private static <K extends Comparable, V> Range<K> coalesce(
-      Range<K> range, V value, @Nullable Entry<Cut<K>, RangeMapEntry<K, V>> entry) {
+      Range<K> range, V value, @CheckForNull Entry<Cut<K>, RangeMapEntry<K, V>> entry) {
     if (entry != null
         && entry.getValue().getKey().isConnected(range)
         && entry.getValue().getValue().equals(value)) {
@@ -179,7 +184,8 @@ public void clear() {
   public Range<K> span() {
     Entry<Cut<K>, RangeMapEntry<K, V>> firstEntry = entriesByLowerBound.firstEntry();
     Entry<Cut<K>, RangeMapEntry<K, V>> lastEntry = entriesByLowerBound.lastEntry();
-    if (firstEntry == null) {
+    // Either both are null or neither is, but we check both to satisfy the nullness checker.
+    if (firstEntry == null || lastEntry == null) {
       throw new NoSuchElementException();
     }
     return Range.create(
@@ -262,8 +268,8 @@ private void split(Cut<K> cut) {
   @Override
   public void merge(
       Range<K> range,
-      @Nullable V value,
-      BiFunction<? super V, ? super V, ? extends V> remappingFunction) {
+      @CheckForNull V value,
+      BiFunction<? super V, ? super @Nullable V, ? extends @Nullable V> remappingFunction) {
     checkNotNull(range);
     checkNotNull(remappingFunction);
 
@@ -334,12 +340,13 @@ private final class AsMapOfRanges extends IteratorBasedAbstractMap<Range<K>, V>
     }
 
     @Override
-    public boolean containsKey(@Nullable Object key) {
+    public boolean containsKey(@CheckForNull Object key) {
       return get(key) != null;
     }
 
     @Override
-    public V get(@Nullable Object key) {
+    @CheckForNull
+    public V get(@CheckForNull Object key) {
       if (key instanceof Range) {
         Range<?> range = (Range<?>) key;
         RangeMapEntry<K, V> rangeMapEntry = entriesByLowerBound.get(range.lowerBound);
@@ -372,42 +379,45 @@ public RangeMap<K, V> subRangeMap(Range<K> subRange) {
 
   @SuppressWarnings("unchecked")
   private RangeMap<K, V> emptySubRangeMap() {
-    return EMPTY_SUB_RANGE_MAP;
+    return (RangeMap<K, V>) (RangeMap<?, ?>) EMPTY_SUB_RANGE_MAP;
   }
 
-  private static final RangeMap EMPTY_SUB_RANGE_MAP =
-      new RangeMap() {
+  @SuppressWarnings("ConstantCaseForConstants") // This RangeMap is immutable.
+  private static final RangeMap<Comparable<?>, Object> EMPTY_SUB_RANGE_MAP =
+      new RangeMap<Comparable<?>, Object>() {
         @Override
-        public @Nullable Object get(Comparable key) {
+        @CheckForNull
+        public Object get(Comparable<?> key) {
           return null;
         }
 
         @Override
-        public @Nullable Entry<Range, Object> getEntry(Comparable key) {
+        @CheckForNull
+        public Entry<Range<Comparable<?>>, Object> getEntry(Comparable<?> key) {
           return null;
         }
 
         @Override
-        public Range span() {
+        public Range<Comparable<?>> span() {
           throw new NoSuchElementException();
         }
 
         @Override
-        public void put(Range range, Object value) {
+        public void put(Range<Comparable<?>> range, Object value) {
           checkNotNull(range);
           throw new IllegalArgumentException(
               "Cannot insert range " + range + " into an empty subRangeMap");
         }
 
         @Override
-        public void putCoalescing(Range range, Object value) {
+        public void putCoalescing(Range<Comparable<?>> range, Object value) {
           checkNotNull(range);
           throw new IllegalArgumentException(
               "Cannot insert range " + range + " into an empty subRangeMap");
         }
 
         @Override
-        public void putAll(RangeMap rangeMap) {
+        public void putAll(RangeMap<Comparable<?>, Object> rangeMap) {
           if (!rangeMap.asMapOfRanges().isEmpty()) {
             throw new IllegalArgumentException(
                 "Cannot putAll(nonEmptyRangeMap) into an empty subRangeMap");
@@ -418,30 +428,33 @@ public void putAll(RangeMap rangeMap) {
         public void clear() {}
 
         @Override
-        public void remove(Range range) {
+        public void remove(Range<Comparable<?>> range) {
           checkNotNull(range);
         }
 
         @Override
-        @SuppressWarnings("rawtypes") // necessary for static EMPTY_SUB_RANGE_MAP instance
-        public void merge(Range range, @Nullable Object value, BiFunction remappingFunction) {
+        public void merge(
+            Range<Comparable<?>> range,
+            @CheckForNull Object value,
+            BiFunction<? super Object, ? super @Nullable Object, ? extends @Nullable Object>
+                remappingFunction) {
           checkNotNull(range);
           throw new IllegalArgumentException(
               "Cannot merge range " + range + " into an empty subRangeMap");
         }
 
         @Override
-        public Map<Range, Object> asMapOfRanges() {
+        public Map<Range<Comparable<?>>, Object> asMapOfRanges() {
           return Collections.emptyMap();
         }
 
         @Override
-        public Map<Range, Object> asDescendingMapOfRanges() {
+        public Map<Range<Comparable<?>>, Object> asDescendingMapOfRanges() {
           return Collections.emptyMap();
         }
 
         @Override
-        public RangeMap subRangeMap(Range range) {
+        public RangeMap<Comparable<?>, Object> subRangeMap(Range<Comparable<?>> range) {
           checkNotNull(range);
           return this;
         }
@@ -456,12 +469,14 @@ private class SubRangeMap implements RangeMap<K, V> {
     }
 
     @Override
-    public @Nullable V get(K key) {
+    @CheckForNull
+    public V get(K key) {
       return subRange.contains(key) ? TreeRangeMap.this.get(key) : null;
     }
 
     @Override
-    public @Nullable Entry<Range<K>, V> getEntry(K key) {
+    @CheckForNull
+    public Entry<Range<K>, V> getEntry(K key) {
       if (subRange.contains(key)) {
         Entry<Range<K>, V> entry = TreeRangeMap.this.getEntry(key);
         if (entry != null) {
@@ -547,8 +562,8 @@ public void remove(Range<K> range) {
     @Override
     public void merge(
         Range<K> range,
-        @Nullable V value,
-        BiFunction<? super V, ? super V, ? extends V> remappingFunction) {
+        @CheckForNull V value,
+        BiFunction<? super V, ? super @Nullable V, ? extends @Nullable V> remappingFunction) {
       checkArgument(
           subRange.encloses(range),
           "Cannot merge range %s into a subRangeMap(%s)",
@@ -589,6 +604,7 @@ Iterator<Entry<Range<K>, V>> entryIterator() {
           return new AbstractIterator<Entry<Range<K>, V>>() {
 
             @Override
+            @CheckForNull
             protected Entry<Range<K>, V> computeNext() {
               if (backingItr.hasNext()) {
                 RangeMapEntry<K, V> entry = backingItr.next();
@@ -605,7 +621,7 @@ protected Entry<Range<K>, V> computeNext() {
     }
 
     @Override
-    public boolean equals(@Nullable Object o) {
+    public boolean equals(@CheckForNull Object o) {
       if (o instanceof RangeMap) {
         RangeMap<?, ?> rangeMap = (RangeMap<?, ?>) o;
         return asMapOfRanges().equals(rangeMap.asMapOfRanges());
@@ -626,12 +642,13 @@ public String toString() {
     class SubRangeMapAsMap extends AbstractMap<Range<K>, V> {
 
       @Override
-      public boolean containsKey(Object key) {
+      public boolean containsKey(@CheckForNull Object key) {
         return get(key) != null;
       }
 
       @Override
-      public V get(Object key) {
+      @CheckForNull
+      public V get(@CheckForNull Object key) {
         try {
           if (key instanceof Range) {
             @SuppressWarnings("unchecked") // we catch ClassCastExceptions
@@ -664,11 +681,13 @@ public V get(Object key) {
       }
 
       @Override
-      public V remove(Object key) {
+      @CheckForNull
+      public V remove(@CheckForNull Object key) {
         V value = get(key);
         if (value != null) {
-          @SuppressWarnings("unchecked") // it's definitely in the map, so safe
-          Range<K> range = (Range<K>) key;
+          // it's definitely in the map, so the cast and requireNonNull are safe
+          @SuppressWarnings("unchecked")
+          Range<K> range = (Range<K>) requireNonNull(key);
           TreeRangeMap.this.remove(range);
           return value;
         }
@@ -697,7 +716,7 @@ private boolean removeEntryIf(Predicate<? super Entry<Range<K>, V>> predicate) {
       public Set<Range<K>> keySet() {
         return new Maps.KeySet<Range<K>, V>(SubRangeMapAsMap.this) {
           @Override
-          public boolean remove(@Nullable Object o) {
+          public boolean remove(@CheckForNull Object o) {
             return SubRangeMapAsMap.this.remove(o) != null;
           }
 
@@ -750,6 +769,7 @@ Iterator<Entry<Range<K>, V>> entryIterator() {
         return new AbstractIterator<Entry<Range<K>, V>>() {
 
           @Override
+          @CheckForNull
           protected Entry<Range<K>, V> computeNext() {
             while (backingItr.hasNext()) {
               RangeMapEntry<K, V> entry = backingItr.next();
@@ -783,7 +803,7 @@ public boolean retainAll(Collection<?> c) {
   }
 
   @Override
-  public boolean equals(@Nullable Object o) {
+  public boolean equals(@CheckForNull Object o) {
     if (o instanceof RangeMap) {
       RangeMap<?, ?> rangeMap = (RangeMap<?, ?>) o;
       return asMapOfRanges().equals(rangeMap.asMapOfRanges());
diff --git a/guava/src/com/google/common/collect/TreeRangeSet.java b/guava/src/com/google/common/collect/TreeRangeSet.java
index 58cdac17a495..7ba71139eb96 100644
--- a/guava/src/com/google/common/collect/TreeRangeSet.java
+++ b/guava/src/com/google/common/collect/TreeRangeSet.java
@@ -30,7 +30,7 @@
 import java.util.NoSuchElementException;
 import java.util.Set;
 import java.util.TreeMap;
-import org.checkerframework.checker.nullness.qual.Nullable;
+import javax.annotation.CheckForNull;
 
 /**
  * An implementation of {@link RangeSet} backed by a {@link TreeMap}.
@@ -40,6 +40,7 @@
  */
 @Beta
 @GwtIncompatible // uses NavigableMap
+@ElementTypesAreNonnullByDefault
 public class TreeRangeSet<C extends Comparable<?>> extends AbstractRangeSet<C>
     implements Serializable {
 
@@ -47,7 +48,7 @@ public class TreeRangeSet<C extends Comparable<?>> extends AbstractRangeSet<C>
 
   /** Creates an empty {@code TreeRangeSet} instance. */
   public static <C extends Comparable<?>> TreeRangeSet<C> create() {
-    return new TreeRangeSet<C>(new TreeMap<Cut<C>, Range<C>>());
+    return new TreeRangeSet<>(new TreeMap<Cut<C>, Range<C>>());
   }
 
   /** Returns a {@code TreeRangeSet} initialized with the ranges in the specified range set. */
@@ -76,8 +77,8 @@ private TreeRangeSet(NavigableMap<Cut<C>, Range<C>> rangesByLowerCut) {
     this.rangesByLowerBound = rangesByLowerCut;
   }
 
-  private transient @Nullable Set<Range<C>> asRanges;
-  private transient @Nullable Set<Range<C>> asDescendingSetOfRanges;
+  @CheckForNull private transient Set<Range<C>> asRanges;
+  @CheckForNull private transient Set<Range<C>> asDescendingSetOfRanges;
 
   @Override
   public Set<Range<C>> asRanges() {
@@ -112,13 +113,14 @@ public int hashCode() {
     }
 
     @Override
-    public boolean equals(@Nullable Object o) {
+    public boolean equals(@CheckForNull Object o) {
       return Sets.equalsImpl(this, o);
     }
   }
 
   @Override
-  public @Nullable Range<C> rangeContaining(C value) {
+  @CheckForNull
+  public Range<C> rangeContaining(C value) {
     checkNotNull(value);
     Entry<Cut<C>, Range<C>> floorEntry = rangesByLowerBound.floorEntry(Cut.belowValue(value));
     if (floorEntry != null && floorEntry.getValue().contains(value)) {
@@ -151,7 +153,8 @@ public boolean encloses(Range<C> range) {
     return floorEntry != null && floorEntry.getValue().encloses(range);
   }
 
-  private @Nullable Range<C> rangeEnclosing(Range<C> range) {
+  @CheckForNull
+  private Range<C> rangeEnclosing(Range<C> range) {
     checkNotNull(range);
     Entry<Cut<C>, Range<C>> floorEntry = rangesByLowerBound.floorEntry(range.lowerBound);
     return (floorEntry != null && floorEntry.getValue().encloses(range))
@@ -163,7 +166,11 @@ public boolean encloses(Range<C> range) {
   public Range<C> span() {
     Entry<Cut<C>, Range<C>> firstEntry = rangesByLowerBound.firstEntry();
     Entry<Cut<C>, Range<C>> lastEntry = rangesByLowerBound.lastEntry();
-    if (firstEntry == null) {
+    if (firstEntry == null || lastEntry == null) {
+      /*
+       * Either both are null or neither is: Either the set is empty, or it's not. But we check both
+       * to make the nullness checker happy.
+       */
       throw new NoSuchElementException();
     }
     return Range.create(firstEntry.getValue().lowerBound, lastEntry.getValue().upperBound);
@@ -267,7 +274,7 @@ private void replaceRangeWithSameLowerBound(Range<C> range) {
     }
   }
 
-  private transient @Nullable RangeSet<C> complement;
+  @CheckForNull private transient RangeSet<C> complement;
 
   @Override
   public RangeSet<C> complement() {
@@ -299,7 +306,7 @@ private RangesByUpperBound(
 
     private NavigableMap<Cut<C>, Range<C>> subMap(Range<Cut<C>> window) {
       if (window.isConnected(upperBoundWindow)) {
-        return new RangesByUpperBound<C>(rangesByLowerBound, window.intersection(upperBoundWindow));
+        return new RangesByUpperBound<>(rangesByLowerBound, window.intersection(upperBoundWindow));
       } else {
         return ImmutableSortedMap.of();
       }
@@ -330,12 +337,13 @@ public Comparator<? super Cut<C>> comparator() {
     }
 
     @Override
-    public boolean containsKey(@Nullable Object key) {
+    public boolean containsKey(@CheckForNull Object key) {
       return get(key) != null;
     }
 
     @Override
-    public Range<C> get(@Nullable Object key) {
+    @CheckForNull
+    public Range<C> get(@CheckForNull Object key) {
       if (key instanceof Cut) {
         try {
           @SuppressWarnings("unchecked") // we catch CCEs
@@ -360,7 +368,7 @@ Iterator<Entry<Cut<C>, Range<C>>> entryIterator() {
        * We want to start the iteration at the first range where the upper bound is in
        * upperBoundWindow.
        */
-      final Iterator<Range<C>> backingItr;
+      Iterator<Range<C>> backingItr;
       if (!upperBoundWindow.hasLowerBound()) {
         backingItr = rangesByLowerBound.values().iterator();
       } else {
@@ -380,6 +388,7 @@ Iterator<Entry<Cut<C>, Range<C>>> entryIterator() {
       }
       return new AbstractIterator<Entry<Cut<C>, Range<C>>>() {
         @Override
+        @CheckForNull
         protected Entry<Cut<C>, Range<C>> computeNext() {
           if (!backingItr.hasNext()) {
             return endOfData();
@@ -406,13 +415,14 @@ Iterator<Entry<Cut<C>, Range<C>>> descendingEntryIterator() {
       } else {
         candidates = rangesByLowerBound.descendingMap().values();
       }
-      final PeekingIterator<Range<C>> backingItr = Iterators.peekingIterator(candidates.iterator());
+      PeekingIterator<Range<C>> backingItr = Iterators.peekingIterator(candidates.iterator());
       if (backingItr.hasNext()
           && upperBoundWindow.upperBound.isLessThan(backingItr.peek().upperBound)) {
         backingItr.next();
       }
       return new AbstractIterator<Entry<Cut<C>, Range<C>>>() {
         @Override
+        @CheckForNull
         protected Entry<Cut<C>, Range<C>> computeNext() {
           if (!backingItr.hasNext()) {
             return endOfData();
@@ -460,7 +470,7 @@ private static final class ComplementRangesByLowerBound<C extends Comparable<?>>
     private ComplementRangesByLowerBound(
         NavigableMap<Cut<C>, Range<C>> positiveRangesByLowerBound, Range<Cut<C>> window) {
       this.positiveRangesByLowerBound = positiveRangesByLowerBound;
-      this.positiveRangesByUpperBound = new RangesByUpperBound<C>(positiveRangesByLowerBound);
+      this.positiveRangesByUpperBound = new RangesByUpperBound<>(positiveRangesByLowerBound);
       this.complementLowerBoundWindow = window;
     }
 
@@ -469,7 +479,7 @@ private NavigableMap<Cut<C>, Range<C>> subMap(Range<Cut<C>> subWindow) {
         return ImmutableSortedMap.of();
       } else {
         subWindow = subWindow.intersection(complementLowerBoundWindow);
-        return new ComplementRangesByLowerBound<C>(positiveRangesByLowerBound, subWindow);
+        return new ComplementRangesByLowerBound<>(positiveRangesByLowerBound, subWindow);
       }
     }
 
@@ -519,9 +529,8 @@ Iterator<Entry<Cut<C>, Range<C>>> entryIterator() {
       } else {
         positiveRanges = positiveRangesByUpperBound.values();
       }
-      final PeekingIterator<Range<C>> positiveItr =
-          Iterators.peekingIterator(positiveRanges.iterator());
-      final Cut<C> firstComplementRangeLowerBound;
+      PeekingIterator<Range<C>> positiveItr = Iterators.peekingIterator(positiveRanges.iterator());
+      Cut<C> firstComplementRangeLowerBound;
       if (complementLowerBoundWindow.contains(Cut.<C>belowAll())
           && (!positiveItr.hasNext() || positiveItr.peek().lowerBound != Cut.<C>belowAll())) {
         firstComplementRangeLowerBound = Cut.belowAll();
@@ -534,6 +543,7 @@ Iterator<Entry<Cut<C>, Range<C>>> entryIterator() {
         Cut<C> nextComplementRangeLowerBound = firstComplementRangeLowerBound;
 
         @Override
+        @CheckForNull
         protected Entry<Cut<C>, Range<C>> computeNext() {
           if (complementLowerBoundWindow.upperBound.isLessThan(nextComplementRangeLowerBound)
               || nextComplementRangeLowerBound == Cut.<C>aboveAll()) {
@@ -570,7 +580,7 @@ Iterator<Entry<Cut<C>, Range<C>>> descendingEntryIterator() {
       boolean inclusive =
           complementLowerBoundWindow.hasUpperBound()
               && complementLowerBoundWindow.upperBoundType() == BoundType.CLOSED;
-      final PeekingIterator<Range<C>> positiveItr =
+      PeekingIterator<Range<C>> positiveItr =
           Iterators.peekingIterator(
               positiveRangesByUpperBound
                   .headMap(startingPoint, inclusive)
@@ -589,12 +599,12 @@ Iterator<Entry<Cut<C>, Range<C>>> descendingEntryIterator() {
       } else {
         cut = positiveRangesByLowerBound.higherKey(Cut.<C>belowAll());
       }
-      final Cut<C> firstComplementRangeUpperBound =
-          MoreObjects.firstNonNull(cut, Cut.<C>aboveAll());
+      Cut<C> firstComplementRangeUpperBound = MoreObjects.firstNonNull(cut, Cut.<C>aboveAll());
       return new AbstractIterator<Entry<Cut<C>, Range<C>>>() {
         Cut<C> nextComplementRangeUpperBound = firstComplementRangeUpperBound;
 
         @Override
+        @CheckForNull
         protected Entry<Cut<C>, Range<C>> computeNext() {
           if (nextComplementRangeUpperBound == Cut.<C>belowAll()) {
             return endOfData();
@@ -622,7 +632,8 @@ public int size() {
     }
 
     @Override
-    public @Nullable Range<C> get(Object key) {
+    @CheckForNull
+    public Range<C> get(@CheckForNull Object key) {
       if (key instanceof Cut) {
         try {
           @SuppressWarnings("unchecked")
@@ -640,7 +651,7 @@ public int size() {
     }
 
     @Override
-    public boolean containsKey(Object key) {
+    public boolean containsKey(@CheckForNull Object key) {
       return get(key) != null;
     }
   }
@@ -695,14 +706,14 @@ private SubRangeSetRangesByLowerBound(
       this.lowerBoundWindow = checkNotNull(lowerBoundWindow);
       this.restriction = checkNotNull(restriction);
       this.rangesByLowerBound = checkNotNull(rangesByLowerBound);
-      this.rangesByUpperBound = new RangesByUpperBound<C>(rangesByLowerBound);
+      this.rangesByUpperBound = new RangesByUpperBound<>(rangesByLowerBound);
     }
 
     private NavigableMap<Cut<C>, Range<C>> subMap(Range<Cut<C>> window) {
       if (!window.isConnected(lowerBoundWindow)) {
         return ImmutableSortedMap.of();
       } else {
-        return new SubRangeSetRangesByLowerBound<C>(
+        return new SubRangeSetRangesByLowerBound<>(
             lowerBoundWindow.intersection(window), restriction, rangesByLowerBound);
       }
     }
@@ -734,12 +745,13 @@ public Comparator<? super Cut<C>> comparator() {
     }
 
     @Override
-    public boolean containsKey(@Nullable Object key) {
+    public boolean containsKey(@CheckForNull Object key) {
       return get(key) != null;
     }
 
     @Override
-    public @Nullable Range<C> get(@Nullable Object key) {
+    @CheckForNull
+    public Range<C> get(@CheckForNull Object key) {
       if (key instanceof Cut) {
         try {
           @SuppressWarnings("unchecked") // we catch CCE's
@@ -772,7 +784,7 @@ Iterator<Entry<Cut<C>, Range<C>>> entryIterator() {
       if (restriction.isEmpty()) {
         return Iterators.emptyIterator();
       }
-      final Iterator<Range<C>> completeRangeItr;
+      Iterator<Range<C>> completeRangeItr;
       if (lowerBoundWindow.upperBound.isLessThan(restriction.lowerBound)) {
         return Iterators.emptyIterator();
       } else if (lowerBoundWindow.lowerBound.isLessThan(restriction.lowerBound)) {
@@ -789,11 +801,12 @@ Iterator<Entry<Cut<C>, Range<C>>> entryIterator() {
                 .values()
                 .iterator();
       }
-      final Cut<Cut<C>> upperBoundOnLowerBounds =
+      Cut<Cut<C>> upperBoundOnLowerBounds =
           Ordering.natural()
               .min(lowerBoundWindow.upperBound, Cut.belowValue(restriction.upperBound));
       return new AbstractIterator<Entry<Cut<C>, Range<C>>>() {
         @Override
+        @CheckForNull
         protected Entry<Cut<C>, Range<C>> computeNext() {
           if (!completeRangeItr.hasNext()) {
             return endOfData();
@@ -817,7 +830,7 @@ Iterator<Entry<Cut<C>, Range<C>>> descendingEntryIterator() {
       Cut<Cut<C>> upperBoundOnLowerBounds =
           Ordering.natural()
               .min(lowerBoundWindow.upperBound, Cut.belowValue(restriction.upperBound));
-      final Iterator<Range<C>> completeRangeItr =
+      Iterator<Range<C>> completeRangeItr =
           rangesByLowerBound
               .headMap(
                   upperBoundOnLowerBounds.endpoint(),
@@ -827,6 +840,7 @@ Iterator<Entry<Cut<C>, Range<C>>> descendingEntryIterator() {
               .iterator();
       return new AbstractIterator<Entry<Cut<C>, Range<C>>>() {
         @Override
+        @CheckForNull
         protected Entry<Cut<C>, Range<C>> computeNext() {
           if (!completeRangeItr.hasNext()) {
             return endOfData();
@@ -876,7 +890,8 @@ public boolean encloses(Range<C> range) {
     }
 
     @Override
-    public @Nullable Range<C> rangeContaining(C value) {
+    @CheckForNull
+    public Range<C> rangeContaining(C value) {
       if (!restriction.contains(value)) {
         return null;
       }
diff --git a/guava/src/com/google/common/collect/TreeTraverser.java b/guava/src/com/google/common/collect/TreeTraverser.java
index 910925240546..b5d2a4293ffa 100644
--- a/guava/src/com/google/common/collect/TreeTraverser.java
+++ b/guava/src/com/google/common/collect/TreeTraverser.java
@@ -26,6 +26,7 @@
 import java.util.Iterator;
 import java.util.Queue;
 import java.util.function.Consumer;
+import javax.annotation.CheckForNull;
 
 /**
  * Views elements of a type {@code T} as nodes in a tree, and provides methods to traverse the trees
@@ -74,6 +75,7 @@
 @Deprecated
 @Beta
 @GwtCompatible
+@ElementTypesAreNonnullByDefault
 public abstract class TreeTraverser<T> {
 
   /**
@@ -222,6 +224,7 @@ private final class PostOrderIterator extends AbstractIterator<T> {
     }
 
     @Override
+    @CheckForNull
     protected T computeNext() {
       while (!stack.isEmpty()) {
         PostOrderNode<T> top = stack.getLast();
diff --git a/guava/src/com/google/common/collect/UnmodifiableIterator.java b/guava/src/com/google/common/collect/UnmodifiableIterator.java
index f2431f449eb1..3ee09456d175 100644
--- a/guava/src/com/google/common/collect/UnmodifiableIterator.java
+++ b/guava/src/com/google/common/collect/UnmodifiableIterator.java
@@ -19,6 +19,7 @@
 import com.google.common.annotations.GwtCompatible;
 import com.google.errorprone.annotations.DoNotCall;
 import java.util.Iterator;
+import org.checkerframework.checker.nullness.qual.Nullable;
 import org.checkerframework.framework.qual.AnnotatedFor;
 
 /**
@@ -33,7 +34,8 @@
  */
 @AnnotatedFor({"nullness"})
 @GwtCompatible
-public abstract class UnmodifiableIterator<E> implements Iterator<E> {
+@ElementTypesAreNonnullByDefault
+public abstract class UnmodifiableIterator<E extends @Nullable Object> implements Iterator<E> {
   /** Constructor for use by subclasses. */
   protected UnmodifiableIterator() {}
 
diff --git a/guava/src/com/google/common/collect/UnmodifiableListIterator.java b/guava/src/com/google/common/collect/UnmodifiableListIterator.java
index 4369ea102a3b..f3d3b921b7dc 100644
--- a/guava/src/com/google/common/collect/UnmodifiableListIterator.java
+++ b/guava/src/com/google/common/collect/UnmodifiableListIterator.java
@@ -19,6 +19,7 @@
 import com.google.common.annotations.GwtCompatible;
 import com.google.errorprone.annotations.DoNotCall;
 import java.util.ListIterator;
+import org.checkerframework.checker.nullness.qual.Nullable;
 
 /**
  * A list iterator that does not support {@link #remove}, {@link #add}, or {@link #set}.
@@ -27,8 +28,9 @@
  * @author Louis Wasserman
  */
 @GwtCompatible
-public abstract class UnmodifiableListIterator<E> extends UnmodifiableIterator<E>
-    implements ListIterator<E> {
+@ElementTypesAreNonnullByDefault
+public abstract class UnmodifiableListIterator<E extends @Nullable Object>
+    extends UnmodifiableIterator<E> implements ListIterator<E> {
   /** Constructor for use by subclasses. */
   protected UnmodifiableListIterator() {}
 
@@ -41,7 +43,7 @@ protected UnmodifiableListIterator() {}
   @Deprecated
   @Override
   @DoNotCall("Always throws UnsupportedOperationException")
-  public final void add(E e) {
+  public final void add(@ParametricNullness E e) {
     throw new UnsupportedOperationException();
   }
 
@@ -54,7 +56,7 @@ public final void add(E e) {
   @Deprecated
   @Override
   @DoNotCall("Always throws UnsupportedOperationException")
-  public final void set(E e) {
+  public final void set(@ParametricNullness E e) {
     throw new UnsupportedOperationException();
   }
 }
diff --git a/guava/src/com/google/common/collect/UnmodifiableSortedMultiset.java b/guava/src/com/google/common/collect/UnmodifiableSortedMultiset.java
index d7a20cca9dcb..31f3c7197776 100644
--- a/guava/src/com/google/common/collect/UnmodifiableSortedMultiset.java
+++ b/guava/src/com/google/common/collect/UnmodifiableSortedMultiset.java
@@ -20,6 +20,7 @@
 import com.google.common.collect.Multisets.UnmodifiableMultiset;
 import java.util.Comparator;
 import java.util.NavigableSet;
+import javax.annotation.CheckForNull;
 import org.checkerframework.checker.nullness.qual.Nullable;
 
 /**
@@ -30,7 +31,8 @@
  * @author Louis Wasserman
  */
 @GwtCompatible(emulated = true)
-final class UnmodifiableSortedMultiset<E> extends UnmodifiableMultiset<E>
+@ElementTypesAreNonnullByDefault
+final class UnmodifiableSortedMultiset<E extends @Nullable Object> extends UnmodifiableMultiset<E>
     implements SortedMultiset<E> {
   UnmodifiableSortedMultiset(SortedMultiset<E> delegate) {
     super(delegate);
@@ -56,13 +58,13 @@ public NavigableSet<E> elementSet() {
     return (NavigableSet<E>) super.elementSet();
   }
 
-  private transient @Nullable UnmodifiableSortedMultiset<E> descendingMultiset;
+  @CheckForNull private transient UnmodifiableSortedMultiset<E> descendingMultiset;
 
   @Override
   public SortedMultiset<E> descendingMultiset() {
     UnmodifiableSortedMultiset<E> result = descendingMultiset;
     if (result == null) {
-      result = new UnmodifiableSortedMultiset<E>(delegate().descendingMultiset());
+      result = new UnmodifiableSortedMultiset<>(delegate().descendingMultiset());
       result.descendingMultiset = this;
       return descendingMultiset = result;
     }
@@ -70,39 +72,46 @@ public SortedMultiset<E> descendingMultiset() {
   }
 
   @Override
+  @CheckForNull
   public Entry<E> firstEntry() {
     return delegate().firstEntry();
   }
 
   @Override
+  @CheckForNull
   public Entry<E> lastEntry() {
     return delegate().lastEntry();
   }
 
   @Override
+  @CheckForNull
   public Entry<E> pollFirstEntry() {
     throw new UnsupportedOperationException();
   }
 
   @Override
+  @CheckForNull
   public Entry<E> pollLastEntry() {
     throw new UnsupportedOperationException();
   }
 
   @Override
-  public SortedMultiset<E> headMultiset(E upperBound, BoundType boundType) {
+  public SortedMultiset<E> headMultiset(@ParametricNullness E upperBound, BoundType boundType) {
     return Multisets.unmodifiableSortedMultiset(delegate().headMultiset(upperBound, boundType));
   }
 
   @Override
   public SortedMultiset<E> subMultiset(
-      E lowerBound, BoundType lowerBoundType, E upperBound, BoundType upperBoundType) {
+      @ParametricNullness E lowerBound,
+      BoundType lowerBoundType,
+      @ParametricNullness E upperBound,
+      BoundType upperBoundType) {
     return Multisets.unmodifiableSortedMultiset(
         delegate().subMultiset(lowerBound, lowerBoundType, upperBound, upperBoundType));
   }
 
   @Override
-  public SortedMultiset<E> tailMultiset(E lowerBound, BoundType boundType) {
+  public SortedMultiset<E> tailMultiset(@ParametricNullness E lowerBound, BoundType boundType) {
     return Multisets.unmodifiableSortedMultiset(delegate().tailMultiset(lowerBound, boundType));
   }
 
diff --git a/guava/src/com/google/common/collect/UsingToStringOrdering.java b/guava/src/com/google/common/collect/UsingToStringOrdering.java
index ed3c89fb7660..70ad6fa2c419 100644
--- a/guava/src/com/google/common/collect/UsingToStringOrdering.java
+++ b/guava/src/com/google/common/collect/UsingToStringOrdering.java
@@ -22,6 +22,7 @@
 
 /** An ordering that uses the natural order of the string representation of the values. */
 @GwtCompatible(serializable = true)
+@ElementTypesAreNonnullByDefault
 final class UsingToStringOrdering extends Ordering<Object> implements Serializable {
   static final UsingToStringOrdering INSTANCE = new UsingToStringOrdering();
 
diff --git a/guava/src/com/google/common/escape/ArrayBasedCharEscaper.java b/guava/src/com/google/common/escape/ArrayBasedCharEscaper.java
index 6e97c6fedcb5..ac6a26b650ba 100644
--- a/guava/src/com/google/common/escape/ArrayBasedCharEscaper.java
+++ b/guava/src/com/google/common/escape/ArrayBasedCharEscaper.java
@@ -16,9 +16,9 @@
 
 import static com.google.common.base.Preconditions.checkNotNull;
 
-import com.google.common.annotations.Beta;
 import com.google.common.annotations.GwtCompatible;
 import java.util.Map;
+import javax.annotation.CheckForNull;
 import org.checkerframework.checker.index.qual.LengthOf;
 
 /**
@@ -41,8 +41,8 @@
  * @author David Beaumont
  * @since 15.0
  */
-@Beta
 @GwtCompatible
+@ElementTypesAreNonnullByDefault
 public abstract class ArrayBasedCharEscaper extends CharEscaper {
   // The replacement array (see ArrayBasedEscaperMap).
   private final char[][] replacements;
@@ -119,9 +119,11 @@ public final String escape(String s) {
    * Escapes a single character using the replacement array and safe range values. If the given
    * character does not have an explicit replacement and lies outside the safe range then {@link
    * #escapeUnsafe} is called.
+   *
+   * @return the replacement characters, or {@code null} if no escaping was required
    */
-  @SuppressWarnings("lowerbound:array.access.unsafe.low")//char types are non negative: https://github.com/kelloggm/checker-framework/issues/192
   @Override
+  @CheckForNull
   protected final char[] escape(char c) {
     if (c < replacementsLength) {
       char[] chars = replacements[c];
@@ -148,5 +150,6 @@ protected final char[] escape(char c) {
    * @return the replacement characters, or {@code null} if no escaping was required
    */
   // TODO(dbeaumont,cpovirk): Rename this something better once refactoring done
+  @CheckForNull
   protected abstract char[] escapeUnsafe(char c);
 }
diff --git a/guava/src/com/google/common/escape/ArrayBasedEscaperMap.java b/guava/src/com/google/common/escape/ArrayBasedEscaperMap.java
index 4c1e70d4e3af..36c6c9fa7b0a 100644
--- a/guava/src/com/google/common/escape/ArrayBasedEscaperMap.java
+++ b/guava/src/com/google/common/escape/ArrayBasedEscaperMap.java
@@ -16,7 +16,6 @@
 
 import static com.google.common.base.Preconditions.checkNotNull;
 
-import com.google.common.annotations.Beta;
 import com.google.common.annotations.GwtCompatible;
 import com.google.common.annotations.VisibleForTesting;
 import java.util.Collections;
@@ -37,8 +36,8 @@
  * @author David Beaumont
  * @since 15.0
  */
-@Beta
 @GwtCompatible
+@ElementTypesAreNonnullByDefault
 public final class ArrayBasedEscaperMap {
   /**
    * Returns a new ArrayBasedEscaperMap for creating ArrayBasedCharEscaper or
@@ -66,9 +65,11 @@ char[][] getReplacementArray() {
   // Creates a replacement array from the given map. The returned array is a
   // linear lookup table of replacement character sequences indexed by the
   // original character value.
-  @SuppressWarnings(value = {"lowerbound:array.length.negative", "lowerbound:array.access.unsafe.low",//char types are non negative: https://github.com/kelloggm/checker-framework/issues/192
-          "upperbound:enhancedfor.type.incompatible"/* LTLengthOf("replacements") is not possible because `replacements` is declared after `map`.
-          Moreover, `max` is maximum value out of all Keys in map and `max + 1` is length of `replacements` array, therefore char `c`is always less than length of `replacements`.*/})
+  @SuppressWarnings({
+    "lowerbound:array.access.unsafe.low", // char types are non negative: https://github.com/kelloggm/checker-framework/issues/192
+    "upperbound:enhancedfor" /* LTLengthOf("replacements") is not possible because `replacements` is declared after `map`.
+      Moreover, `max` is maximum value out of all Keys in map and `max + 1` is length of `replacements` array, therefore char `c`is always less than length of `replacements`.*/
+  })
   @VisibleForTesting
   static char[][] createReplacementArray(Map<Character, String> map) {
     checkNotNull(map); // GWT specific check (do not optimize)
diff --git a/guava/src/com/google/common/escape/ArrayBasedUnicodeEscaper.java b/guava/src/com/google/common/escape/ArrayBasedUnicodeEscaper.java
index d98ad0563ea7..7e8513208615 100644
--- a/guava/src/com/google/common/escape/ArrayBasedUnicodeEscaper.java
+++ b/guava/src/com/google/common/escape/ArrayBasedUnicodeEscaper.java
@@ -16,9 +16,9 @@
 
 import static com.google.common.base.Preconditions.checkNotNull;
 
-import com.google.common.annotations.Beta;
 import com.google.common.annotations.GwtCompatible;
 import java.util.Map;
+import javax.annotation.CheckForNull;
 import org.checkerframework.checker.index.qual.GTENegativeOne;
 import org.checkerframework.checker.index.qual.IndexOrHigh;
 import org.checkerframework.checker.index.qual.LengthOf;
@@ -44,8 +44,8 @@
  * @author David Beaumont
  * @since 15.0
  */
-@Beta
 @GwtCompatible
+@ElementTypesAreNonnullByDefault
 public abstract class ArrayBasedUnicodeEscaper extends UnicodeEscaper {
   // The replacement array (see ArrayBasedEscaperMap).
   private final char[][] replacements;
@@ -161,8 +161,11 @@ public final String escape(String s) {
    * Escapes a single Unicode code point using the replacement array and safe range values. If the
    * given character does not have an explicit replacement and lies outside the safe range then
    * {@link #escapeUnsafe} is called.
+   *
+   * @return the replacement characters, or {@code null} if no escaping was required
    */
   @Override
+  @CheckForNull
   protected final char[] escape(@NonNegative int cp) {
     if (cp < replacementsLength) {
       char[] chars = replacements[cp];
@@ -203,5 +206,6 @@ protected final char[] escape(@NonNegative int cp) {
    * @param cp the Unicode code point to escape
    * @return the replacement characters, or {@code null} if no escaping was required
    */
+  @CheckForNull
   protected abstract char[] escapeUnsafe(int cp);
 }
diff --git a/guava/src/com/google/common/escape/CharEscaper.java b/guava/src/com/google/common/escape/CharEscaper.java
index 7c33d7110708..8c1d33c2ff25 100644
--- a/guava/src/com/google/common/escape/CharEscaper.java
+++ b/guava/src/com/google/common/escape/CharEscaper.java
@@ -16,8 +16,8 @@
 
 import static com.google.common.base.Preconditions.checkNotNull;
 
-import com.google.common.annotations.Beta;
 import com.google.common.annotations.GwtCompatible;
+import javax.annotation.CheckForNull;
 import org.checkerframework.checker.index.qual.IndexOrHigh;
 import org.checkerframework.checker.index.qual.LTEqLengthOf;
 import org.checkerframework.checker.index.qual.LTLengthOf;
@@ -43,8 +43,8 @@
  * @author Sven Mawson
  * @since 15.0
  */
-@Beta
 @GwtCompatible
+@ElementTypesAreNonnullByDefault
 public abstract class CharEscaper extends Escaper {
   /** Constructor for use by subclasses. */
   protected CharEscaper() {}
@@ -84,6 +84,7 @@ public String escape(String string) {
    * @param c the character to escape if necessary
    * @return the replacement characters, or {@code null} if no escaping was needed
    */
+  @CheckForNull
   protected abstract char[] escape(char c);
 
   /**
@@ -97,11 +98,12 @@ public String escape(String string) {
    * @return the escaped form of {@code string}
    * @throws NullPointerException if {@code string} is null
    */
-  @SuppressWarnings(value = {"upperbound:assignment.type.incompatible",/*
-   (1) Because of System.arraycopy() method, `rlen` is required to be @LTLengthOf(value={"r", "dest"}, offset={"-1", "destIndex - 1"}).
-   Since r = escape(), can't annotate `escape()` return type as @LTLengthOf(value={"r", "dest"}, offset={"-1", "destIndex - 1"}).*/
-          "upperbound:compound.assignment.type.incompatible"/*(2): `destIndex` is always @LTEqLengthOf("dest") because `dest` array
-          will always be regrow when `destSize` is less than `sizeNeeded`*/})
+  @SuppressWarnings({
+    "upperbound:assignment", /* (1) Because of System.arraycopy() method, `rlen` is required to be @LTLengthOf(value={"r", "dest"}, offset={"-1", "destIndex - 1"}).
+      Since r = escape(), can't annotate `escape()` return type as @LTLengthOf(value={"r", "dest"}, offset={"-1", "destIndex - 1"}).*/
+    "upperbound:compound.assignment"/*(2): `destIndex` is always @LTEqLengthOf("dest") because `dest` array
+       will always be regrow when `destSize` is less than `sizeNeeded`*/
+  })
   protected final String escapeSlow(String s, @IndexOrHigh("#1") int index) {
     int slen = s.length();
 
@@ -168,8 +170,6 @@ protected final String escapeSlow(String s, @IndexOrHigh("#1") int index) {
    * Helper method to grow the character buffer as needed, this only happens once in a while so it's
    * ok if it's in a method call. If the index passed in is 0 then no copying will be done.
    */
-  @SuppressWarnings("upperbound:argument.type.incompatible")//index should infer @LessThan("#3 + 1") as same as @LTEqLengthOf("copy")
-  //this is a similar improvement to this issue: https://github.com/typetools/checker-framework/issues/2029
   private static char[] growBuffer(char[] dest, @LTEqLengthOf("#1") @LessThan("#3 + 1")  int index, int size) {
     if (size < 0) { // overflow - should be OutOfMemoryError but GWT/j2cl don't support it
       throw new AssertionError("Cannot increase internal buffer any further");
diff --git a/guava/src/com/google/common/escape/CharEscaperBuilder.java b/guava/src/com/google/common/escape/CharEscaperBuilder.java
index 7ff25d5f7b5a..2fdb7d2dd711 100644
--- a/guava/src/com/google/common/escape/CharEscaperBuilder.java
+++ b/guava/src/com/google/common/escape/CharEscaperBuilder.java
@@ -16,15 +16,16 @@
 
 import static com.google.common.base.Preconditions.checkNotNull;
 
-import com.google.common.annotations.Beta;
 import com.google.common.annotations.GwtCompatible;
 import com.google.errorprone.annotations.CanIgnoreReturnValue;
 import java.util.HashMap;
 import java.util.Map;
 import java.util.Map.Entry;
+import javax.annotation.CheckForNull;
 import org.checkerframework.checker.index.qual.GTENegativeOne;
 import org.checkerframework.checker.index.qual.LTEqLengthOf;
 import org.checkerframework.checker.index.qual.LTLengthOf;
+import org.checkerframework.checker.nullness.qual.Nullable;
 
 /**
  * Simple helper class to build a "sparse" array of objects based on the indexes that were added to
@@ -35,18 +36,18 @@
  * @author Sven Mawson
  * @since 15.0
  */
-@Beta
 @GwtCompatible
+@ElementTypesAreNonnullByDefault
 public final class CharEscaperBuilder {
   /**
    * Simple decorator that turns an array of replacement char[]s into a CharEscaper, this results in
    * a very fast escape method.
    */
   private static class CharArrayDecorator extends CharEscaper {
-    private final char[][] replacements;
+    private final char[] @Nullable [] replacements;
     private final @LTEqLengthOf("replacements") int replaceLength;
 
-    CharArrayDecorator(char[][] replacements) {
+    CharArrayDecorator(char[] @Nullable [] replacements) {
       this.replacements = replacements;
       this.replaceLength = replacements.length;
     }
@@ -68,8 +69,8 @@ public String escape(String s) {
       return s;
     }
 
-    @SuppressWarnings("lowerbound:array.access.unsafe.low")//char types are non negative: https://github.com/kelloggm/checker-framework/issues/192
     @Override
+    @CheckForNull
     protected char[] escape(char c) {
       return c < replaceLength ? replacements[c] : null;
     }
@@ -113,11 +114,7 @@ public CharEscaperBuilder addEscapes(char[] cs, String r) {
    *
    * @return a "sparse" array that holds the replacement mappings.
    */
-  @SuppressWarnings(value = {"lowerbound:array.access.unsafe.low",//Character types are non negative: https://github.com/kelloggm/checker-framework/issues/192
-          "upperbound:enhancedfor.type.incompatible"/*(2):
-          Since `max` is maximum index is the value of the highest character that has been seen, `max + 1` is larger than any of the key values in map.
-          Therefore, key values in map can be indexed by the `result` array.*/})
-  public char[][] toArray() {
+  public char[] @Nullable [] toArray() {
     char[][] result = new char[max + 1][];
     for (Entry<@LTLengthOf("result") Character, String> entry : map.entrySet()) { //(2)
       result[entry.getKey()] = entry.getValue().toCharArray();
diff --git a/guava/src/com/google/common/escape/ElementTypesAreNonnullByDefault.java b/guava/src/com/google/common/escape/ElementTypesAreNonnullByDefault.java
new file mode 100644
index 000000000000..992c9a3e4d84
--- /dev/null
+++ b/guava/src/com/google/common/escape/ElementTypesAreNonnullByDefault.java
@@ -0,0 +1,41 @@
+/*
+ * Copyright (C) 2021 The Guava Authors
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package com.google.common.escape;
+
+import static java.lang.annotation.ElementType.FIELD;
+import static java.lang.annotation.ElementType.METHOD;
+import static java.lang.annotation.ElementType.PARAMETER;
+import static java.lang.annotation.ElementType.TYPE;
+import static java.lang.annotation.RetentionPolicy.RUNTIME;
+
+import com.google.common.annotations.GwtCompatible;
+import java.lang.annotation.Retention;
+import java.lang.annotation.Target;
+import javax.annotation.Nonnull;
+import javax.annotation.meta.TypeQualifierDefault;
+
+/**
+ * Marks all "top-level" types as non-null in a way that is recognized by Kotlin. Note that this
+ * unfortunately includes type-variable usages, so we also provide {@link ParametricNullness} to
+ * "undo" it as best we can.
+ */
+@GwtCompatible
+@Retention(RUNTIME)
+@Target(TYPE)
+@TypeQualifierDefault({FIELD, METHOD, PARAMETER})
+@Nonnull
+@interface ElementTypesAreNonnullByDefault {}
diff --git a/guava/src/com/google/common/escape/Escaper.java b/guava/src/com/google/common/escape/Escaper.java
index 0d32a09a1e18..31b7df0e64ab 100644
--- a/guava/src/com/google/common/escape/Escaper.java
+++ b/guava/src/com/google/common/escape/Escaper.java
@@ -56,6 +56,7 @@
  */
 @DoNotMock("Use Escapers.nullEscaper() or another methods from the *Escapers classes")
 @GwtCompatible
+@ElementTypesAreNonnullByDefault
 public abstract class Escaper {
   // TODO(dbeaumont): evaluate custom implementations, considering package private constructor.
   /** Constructor for use by subclasses. */
@@ -84,13 +85,7 @@ protected Escaper() {}
    */
   public abstract String escape(String string);
 
-  private final Function<String, String> asFunction =
-      new Function<String, String>() {
-        @Override
-        public String apply(String from) {
-          return escape(from);
-        }
-      };
+  private final Function<String, String> asFunction = this::escape;
 
   /** Returns a {@link Function} that invokes {@link #escape(String)} on this escaper. */
   public final Function<String, String> asFunction() {
diff --git a/guava/src/com/google/common/escape/Escapers.java b/guava/src/com/google/common/escape/Escapers.java
index 98a97e528106..3d6ac9ef1d5b 100644
--- a/guava/src/com/google/common/escape/Escapers.java
+++ b/guava/src/com/google/common/escape/Escapers.java
@@ -16,11 +16,11 @@
 
 import static com.google.common.base.Preconditions.checkNotNull;
 
-import com.google.common.annotations.Beta;
 import com.google.common.annotations.GwtCompatible;
 import com.google.errorprone.annotations.CanIgnoreReturnValue;
 import java.util.HashMap;
 import java.util.Map;
+import javax.annotation.CheckForNull;
 import org.checkerframework.checker.index.qual.NonNegative;
 import org.checkerframework.checker.nullness.qual.Nullable;
 
@@ -31,8 +31,8 @@
  * @author David Beaumont
  * @since 15.0
  */
-@Beta
 @GwtCompatible
+@ElementTypesAreNonnullByDefault
 public final class Escapers {
   private Escapers() {}
 
@@ -53,6 +53,7 @@ public String escape(String string) {
         }
 
         @Override
+        @CheckForNull
         protected char[] escape(char c) {
           // TODO: Fix tests not to call this directly and make it throw an error.
           return null;
@@ -91,12 +92,11 @@ public static Builder builder() {
    * @author David Beaumont
    * @since 15.0
    */
-  @Beta
   public static final class Builder {
     private final Map<Character, String> replacementMap = new HashMap<>();
     private char safeMin = Character.MIN_VALUE;
     private char safeMax = Character.MAX_VALUE;
-    private String unsafeReplacement = null;
+    @CheckForNull private String unsafeReplacement = null;
 
     // The constructor is exposed via the builder() method above.
     private Builder() {}
@@ -152,10 +152,12 @@ public Builder addEscape(char c, String replacement) {
     /** Returns a new escaper based on the current state of the builder. */
     public Escaper build() {
       return new ArrayBasedCharEscaper(replacementMap, safeMin, safeMax) {
+        @CheckForNull
         private final char[] replacementChars =
             unsafeReplacement != null ? unsafeReplacement.toCharArray() : null;
 
         @Override
+        @CheckForNull
         protected char[] escapeUnsafe(char c) {
           return replacementChars;
         }
@@ -199,6 +201,7 @@ static UnicodeEscaper asUnicodeEscaper(Escaper escaper) {
    * @param c the character to escape if necessary
    * @return the replacement string, or {@code null} if no escaping was needed
    */
+  @CheckForNull
   public static String computeReplacement(CharEscaper escaper, char c) {
     return stringOrNull(escaper.escape(c));
   }
@@ -212,11 +215,13 @@ public static String computeReplacement(CharEscaper escaper, char c) {
    * @param cp the Unicode code point to escape if necessary
    * @return the replacement string, or {@code null} if no escaping was needed
    */
+  @CheckForNull
   public static String computeReplacement(UnicodeEscaper escaper, @NonNegative int cp) {
     return stringOrNull(escaper.escape(cp));
   }
 
-  private static String stringOrNull(char[] in) {
+  @CheckForNull
+  private static String stringOrNull(@CheckForNull char[] in) {
     return (in == null) ? null : new String(in);
   }
 
@@ -236,9 +241,10 @@ Therefore, array access output[n] in for loop( n from 0 to hiChars.length - 1) i
      - output.length range from 1 to MAX + 1, therefore array access output[hiCount] is safe.
   */
   /** Private helper to wrap a CharEscaper as a UnicodeEscaper. */
-  private static UnicodeEscaper wrap(final CharEscaper escaper) {
+  private static UnicodeEscaper wrap(CharEscaper escaper) {
     return new UnicodeEscaper() {
       @Override
+      @CheckForNull
       protected char[] escape(int cp) {
         // If a code point maps to a single character, just escape that.
         if (cp < Character.MIN_SUPPLEMENTARY_CODE_POINT) {
diff --git a/guava/src/com/google/common/escape/ParametricNullness.java b/guava/src/com/google/common/escape/ParametricNullness.java
new file mode 100644
index 000000000000..d9412065ffd9
--- /dev/null
+++ b/guava/src/com/google/common/escape/ParametricNullness.java
@@ -0,0 +1,52 @@
+/*
+ * Copyright (C) 2021 The Guava Authors
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package com.google.common.escape;
+
+import static java.lang.annotation.ElementType.FIELD;
+import static java.lang.annotation.ElementType.METHOD;
+import static java.lang.annotation.ElementType.PARAMETER;
+import static java.lang.annotation.RetentionPolicy.RUNTIME;
+
+import com.google.common.annotations.GwtCompatible;
+import java.lang.annotation.Retention;
+import java.lang.annotation.Target;
+
+/**
+ * Marks a "top-level" type-variable usage as the closest we can get to "non-nullable when
+ * non-nullable; nullable when nullable" (like the Android <a
+ * href="https://android.googlesource.com/platform/libcore/+/master/luni/src/main/java/libcore/util/NullFromTypeParam.java">{@code
+ * NullFromTypeParam}</a>).
+ *
+ * <p>Consumers of this annotation include:
+ *
+ * <ul>
+ *   <li>Kotlin, for which it makes the type-variable usage (a) a Kotlin platform type when the type
+ *       argument is non-nullable and (b) nullable when the type argument is nullable. We use this
+ *       to "undo" {@link ElementTypesAreNonnullByDefault}.
+ *   <li><a href="https://developers.google.com/j2objc">J2ObjC</a>
+ *   <li>{@code NullPointerTester}, at least in the Android backport (where the type-use annotations
+ *       {@code NullPointerTester} would need are not available) and in case of <a
+ *       href="https://bugs.openjdk.java.net/browse/JDK-8202469">JDK-8202469</a>
+ * </ul>
+ *
+ */
+@GwtCompatible
+@Retention(RUNTIME)
+@Target({FIELD, METHOD, PARAMETER})
+@javax.annotation.meta.TypeQualifierNickname
+@javax.annotation.Nonnull(when = javax.annotation.meta.When.UNKNOWN)
+@interface ParametricNullness {}
diff --git a/guava/src/com/google/common/escape/Platform.java b/guava/src/com/google/common/escape/Platform.java
index 99a7d4f0f237..dc6610c041bb 100644
--- a/guava/src/com/google/common/escape/Platform.java
+++ b/guava/src/com/google/common/escape/Platform.java
@@ -22,6 +22,7 @@
  * @author Jesse Wilson
  */
 @GwtCompatible(emulated = true)
+@ElementTypesAreNonnullByDefault
 final class Platform {
   private Platform() {}
 
diff --git a/guava/src/com/google/common/escape/UnicodeEscaper.java b/guava/src/com/google/common/escape/UnicodeEscaper.java
index ca956066627f..34690ea08f43 100644
--- a/guava/src/com/google/common/escape/UnicodeEscaper.java
+++ b/guava/src/com/google/common/escape/UnicodeEscaper.java
@@ -16,8 +16,8 @@
 
 import static com.google.common.base.Preconditions.checkNotNull;
 
-import com.google.common.annotations.Beta;
 import com.google.common.annotations.GwtCompatible;
+import javax.annotation.CheckForNull;
 import org.checkerframework.checker.index.qual.IndexFor;
 import org.checkerframework.checker.index.qual.IndexOrHigh;
 import org.checkerframework.checker.index.qual.LTEqLengthOf;
@@ -55,8 +55,8 @@
  * @author David Beaumont
  * @since 15.0
  */
-@Beta
 @GwtCompatible
+@ElementTypesAreNonnullByDefault
 public abstract class UnicodeEscaper extends Escaper {
   /** The amount of padding (chars) to use when growing the escape buffer. */
   private static final int DEST_PAD = 32;
@@ -83,6 +83,7 @@ protected UnicodeEscaper() {}
    * @param cp the Unicode code point to escape if necessary
    * @return the replacement characters, or {@code null} if no escaping was needed
    */
+  @CheckForNull
   protected abstract char[] escape(@NonNegative int cp);
 
   /**
diff --git a/guava/src/com/google/common/eventbus/AllowConcurrentEvents.java b/guava/src/com/google/common/eventbus/AllowConcurrentEvents.java
index 4c749b401991..28bc4b23e0c3 100644
--- a/guava/src/com/google/common/eventbus/AllowConcurrentEvents.java
+++ b/guava/src/com/google/common/eventbus/AllowConcurrentEvents.java
@@ -14,7 +14,6 @@
 
 package com.google.common.eventbus;
 
-import com.google.common.annotations.Beta;
 import java.lang.annotation.ElementType;
 import java.lang.annotation.Retention;
 import java.lang.annotation.RetentionPolicy;
@@ -31,5 +30,5 @@
  */
 @Retention(RetentionPolicy.RUNTIME)
 @Target(ElementType.METHOD)
-@Beta
+@ElementTypesAreNonnullByDefault
 public @interface AllowConcurrentEvents {}
diff --git a/guava/src/com/google/common/eventbus/AsyncEventBus.java b/guava/src/com/google/common/eventbus/AsyncEventBus.java
index 8650a8d86eea..4f387a712841 100644
--- a/guava/src/com/google/common/eventbus/AsyncEventBus.java
+++ b/guava/src/com/google/common/eventbus/AsyncEventBus.java
@@ -14,7 +14,6 @@
 
 package com.google.common.eventbus;
 
-import com.google.common.annotations.Beta;
 import java.util.concurrent.Executor;
 
 /**
@@ -24,7 +23,7 @@
  * @author Cliff Biffle
  * @since 10.0
  */
-@Beta
+@ElementTypesAreNonnullByDefault
 public class AsyncEventBus extends EventBus {
 
   /**
diff --git a/guava/src/com/google/common/eventbus/DeadEvent.java b/guava/src/com/google/common/eventbus/DeadEvent.java
index 6dbfee527dbc..2cdb23f712d7 100644
--- a/guava/src/com/google/common/eventbus/DeadEvent.java
+++ b/guava/src/com/google/common/eventbus/DeadEvent.java
@@ -16,7 +16,6 @@
 
 import static com.google.common.base.Preconditions.checkNotNull;
 
-import com.google.common.annotations.Beta;
 import com.google.common.base.MoreObjects;
 
 /**
@@ -28,7 +27,7 @@
  * @author Cliff Biffle
  * @since 10.0
  */
-@Beta
+@ElementTypesAreNonnullByDefault
 public class DeadEvent {
 
   private final Object source;
diff --git a/guava/src/com/google/common/eventbus/Dispatcher.java b/guava/src/com/google/common/eventbus/Dispatcher.java
index 11e2de191c70..ff1ae2a197a4 100644
--- a/guava/src/com/google/common/eventbus/Dispatcher.java
+++ b/guava/src/com/google/common/eventbus/Dispatcher.java
@@ -31,6 +31,7 @@
  *
  * @author Colin Decker
  */
+@ElementTypesAreNonnullByDefault
 abstract class Dispatcher {
 
   /**
diff --git a/guava/src/com/google/common/eventbus/ElementTypesAreNonnullByDefault.java b/guava/src/com/google/common/eventbus/ElementTypesAreNonnullByDefault.java
new file mode 100644
index 000000000000..e8542bba63ec
--- /dev/null
+++ b/guava/src/com/google/common/eventbus/ElementTypesAreNonnullByDefault.java
@@ -0,0 +1,41 @@
+/*
+ * Copyright (C) 2021 The Guava Authors
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package com.google.common.eventbus;
+
+import static java.lang.annotation.ElementType.FIELD;
+import static java.lang.annotation.ElementType.METHOD;
+import static java.lang.annotation.ElementType.PARAMETER;
+import static java.lang.annotation.ElementType.TYPE;
+import static java.lang.annotation.RetentionPolicy.RUNTIME;
+
+import com.google.common.annotations.GwtCompatible;
+import java.lang.annotation.Retention;
+import java.lang.annotation.Target;
+import javax.annotation.Nonnull;
+import javax.annotation.meta.TypeQualifierDefault;
+
+/**
+ * Marks all "top-level" types as non-null in a way that is recognized by Kotlin. Note that this
+ * unfortunately includes type-variable usages, so we also provide {@link ParametricNullness} to
+ * "undo" it as best we can.
+ */
+@GwtCompatible
+@Retention(RUNTIME)
+@Target(TYPE)
+@TypeQualifierDefault({FIELD, METHOD, PARAMETER})
+@Nonnull
+@interface ElementTypesAreNonnullByDefault {}
diff --git a/guava/src/com/google/common/eventbus/EventBus.java b/guava/src/com/google/common/eventbus/EventBus.java
index 31eb8551483e..a4b06fb40517 100644
--- a/guava/src/com/google/common/eventbus/EventBus.java
+++ b/guava/src/com/google/common/eventbus/EventBus.java
@@ -16,7 +16,6 @@
 
 import static com.google.common.base.Preconditions.checkNotNull;
 
-import com.google.common.annotations.Beta;
 import com.google.common.base.MoreObjects;
 import com.google.common.util.concurrent.MoreExecutors;
 import java.lang.reflect.Method;
@@ -29,6 +28,62 @@
 /**
  * Dispatches events to listeners, and provides ways for listeners to register themselves.
  *
+ * <h2>Avoid EventBus</h2>
+ *
+ * <p><b>We recommend against using EventBus.</b> It was designed many years ago, and newer
+ * libraries offer better ways to decouple components and react to events.
+ *
+ * <p>To decouple components, we recommend a dependency-injection framework. For Android code, most
+ * apps use <a href="https://dagger.dev">Dagger</a>. For server code, common options include <a
+ * href="https://github.com/google/guice/wiki/Motivation">Guice</a> and <a
+ * href="https://docs.spring.io/spring-framework/docs/current/reference/html/core.html#beans-introduction">Spring</a>.
+ * Frameworks typically offer a way to register multiple listeners independently and then request
+ * them together as a set (<a href="https://dagger.dev/dev-guide/multibindings">Dagger</a>, <a
+ * href="https://github.com/google/guice/wiki/Multibindings">Guice</a>, <a
+ * href="https://docs.spring.io/spring-framework/docs/current/reference/html/core.html#beans-autowired-annotation">Spring</a>).
+ *
+ * <p>To react to events, we recommend a reactive-streams framework like <a
+ * href="https://github.com/ReactiveX/RxJava/wiki">RxJava</a> (supplemented with its <a
+ * href="https://github.com/ReactiveX/RxAndroid">RxAndroid</a> extension if you are building for
+ * Android) or <a href="https://projectreactor.io/">Project Reactor</a>. (For the basics of
+ * translating code from using an event bus to using a reactive-streams framework, see these two
+ * guides: <a href="https://blog.jkl.gg/implementing-an-event-bus-with-rxjava-rxbus/">1</a>, <a
+ * href="https://lorentzos.com/rxjava-as-event-bus-the-right-way-10a36bdd49ba">2</a>.) Some usages
+ * of EventBus may be better written using <a
+ * href="https://kotlinlang.org/docs/coroutines-guide.html">Kotlin coroutines</a>, including <a
+ * href="https://kotlinlang.org/docs/flow.html">Flow</a> and <a
+ * href="https://kotlinlang.org/docs/channels.html">Channels</a>. Yet other usages are better served
+ * by individual libraries that provide specialized support for particular use cases.
+ *
+ * <p>Disadvantages of EventBus include:
+ *
+ * <ul>
+ *   <li>It makes the cross-references between producer and subscriber harder to find. This can
+ *       complicate debugging, lead to unintentional reentrant calls, and force apps to eagerly
+ *       initialize all possible subscribers at startup time.
+ *   <li>It uses reflection in ways that break when code is processed by optimizers/minimizers like
+ *       <a href="https://developer.android.com/studio/build/shrink-code">R8 and Proguard</a>.
+ *   <li>It doesn't offer a way to wait for multiple events before taking action. For example, it
+ *       doesn't offer a way to wait for multiple producers to all report that they're "ready," nor
+ *       does it offer a way to batch multiple events from a single producer together.
+ *   <li>It doesn't support backpressure and other features needed for resilience.
+ *   <li>It doesn't provide much control of threading.
+ *   <li>It doesn't offer much monitoring.
+ *   <li>It doesn't propagate exceptions, so apps don't have a way to react to them.
+ *   <li>It doesn't interoperate well with RxJava, coroutines, and other more commonly used
+ *       alternatives.
+ *   <li>It imposes requirements on the lifecycle of its subscribers. For example, if an event
+ *       occurs between when one subscriber is removed and the next subscriber is added, the event
+ *       is dropped.
+ *   <li>Its performance is suboptimal, especially under Android.
+ *   <li>It <a href="https://github.com/google/guava/issues/1431">doesn't support parameterized
+ *       types</a>.
+ *   <li>With the introduction of lambdas in Java 8, EventBus went from less verbose than listeners
+ *       to <a href="https://github.com/google/guava/issues/3311">more verbose</a>.
+ * </ul>
+ *
+ * <h2>EventBus Summary</h2>
+ *
  * <p>The EventBus allows publish-subscribe-style communication between components without requiring
  * the components to explicitly register with one another (and thus be aware of each other). It is
  * designed exclusively to replace traditional Java in-process event distribution using explicit
@@ -92,7 +147,7 @@
  * @author Cliff Biffle
  * @since 10.0
  */
-@Beta
+@ElementTypesAreNonnullByDefault
 public class EventBus {
 
   private static final Logger logger = Logger.getLogger(EventBus.class.getName());
@@ -101,7 +156,6 @@ public class EventBus {
   private final Executor executor;
   private final SubscriberExceptionHandler exceptionHandler;
 
-  @SuppressWarnings("assignment.type.incompatible") // The SubscriberRegistry won't use the bus until it is full initialized
   private final SubscriberRegistry subscribers = new SubscriberRegistry(this);
   private final Dispatcher dispatcher;
 
@@ -238,6 +292,7 @@ private static Logger logger(SubscriberExceptionContext context) {
       return Logger.getLogger(EventBus.class.getName() + "." + context.getEventBus().identifier());
     }
 
+    @SuppressWarnings("upperbound:array.access.unsafe.high.constant")
     private static String message(SubscriberExceptionContext context) {
       Method method = context.getSubscriberMethod();
       return "Exception thrown by subscriber method "
diff --git a/guava/src/com/google/common/eventbus/ParametricNullness.java b/guava/src/com/google/common/eventbus/ParametricNullness.java
new file mode 100644
index 000000000000..ac91392f75eb
--- /dev/null
+++ b/guava/src/com/google/common/eventbus/ParametricNullness.java
@@ -0,0 +1,52 @@
+/*
+ * Copyright (C) 2021 The Guava Authors
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package com.google.common.eventbus;
+
+import static java.lang.annotation.ElementType.FIELD;
+import static java.lang.annotation.ElementType.METHOD;
+import static java.lang.annotation.ElementType.PARAMETER;
+import static java.lang.annotation.RetentionPolicy.RUNTIME;
+
+import com.google.common.annotations.GwtCompatible;
+import java.lang.annotation.Retention;
+import java.lang.annotation.Target;
+
+/**
+ * Marks a "top-level" type-variable usage as the closest we can get to "non-nullable when
+ * non-nullable; nullable when nullable" (like the Android <a
+ * href="https://android.googlesource.com/platform/libcore/+/master/luni/src/main/java/libcore/util/NullFromTypeParam.java">{@code
+ * NullFromTypeParam}</a>).
+ *
+ * <p>Consumers of this annotation include:
+ *
+ * <ul>
+ *   <li>Kotlin, for which it makes the type-variable usage (a) a Kotlin platform type when the type
+ *       argument is non-nullable and (b) nullable when the type argument is nullable. We use this
+ *       to "undo" {@link ElementTypesAreNonnullByDefault}.
+ *   <li><a href="https://developers.google.com/j2objc">J2ObjC</a>
+ *   <li>{@code NullPointerTester}, at least in the Android backport (where the type-use annotations
+ *       {@code NullPointerTester} would need are not available) and in case of <a
+ *       href="https://bugs.openjdk.java.net/browse/JDK-8202469">JDK-8202469</a>
+ * </ul>
+ *
+ */
+@GwtCompatible
+@Retention(RUNTIME)
+@Target({FIELD, METHOD, PARAMETER})
+@javax.annotation.meta.TypeQualifierNickname
+@javax.annotation.Nonnull(when = javax.annotation.meta.When.UNKNOWN)
+@interface ParametricNullness {}
diff --git a/guava/src/com/google/common/eventbus/Subscribe.java b/guava/src/com/google/common/eventbus/Subscribe.java
index 52b999d98f87..88477f1bae75 100644
--- a/guava/src/com/google/common/eventbus/Subscribe.java
+++ b/guava/src/com/google/common/eventbus/Subscribe.java
@@ -14,7 +14,6 @@
 
 package com.google.common.eventbus;
 
-import com.google.common.annotations.Beta;
 import java.lang.annotation.ElementType;
 import java.lang.annotation.Retention;
 import java.lang.annotation.RetentionPolicy;
@@ -36,5 +35,5 @@
  */
 @Retention(RetentionPolicy.RUNTIME)
 @Target(ElementType.METHOD)
-@Beta
+@ElementTypesAreNonnullByDefault
 public @interface Subscribe {}
diff --git a/guava/src/com/google/common/eventbus/Subscriber.java b/guava/src/com/google/common/eventbus/Subscriber.java
index ddc4963c9609..71ee197c9b25 100644
--- a/guava/src/com/google/common/eventbus/Subscriber.java
+++ b/guava/src/com/google/common/eventbus/Subscriber.java
@@ -21,7 +21,7 @@
 import java.lang.reflect.InvocationTargetException;
 import java.lang.reflect.Method;
 import java.util.concurrent.Executor;
-import org.checkerframework.checker.nullness.qual.Nullable;
+import javax.annotation.CheckForNull;
 
 /**
  * A subscriber method on a specific object, plus the executor that should be used for dispatching
@@ -32,6 +32,7 @@
  *
  * @author Colin Decker
  */
+@ElementTypesAreNonnullByDefault
 class Subscriber {
 
   /** Creates a {@code Subscriber} for {@code method} on {@code listener}. */
@@ -63,16 +64,13 @@ private Subscriber(EventBus bus, Object target, Method method) {
   }
 
   /** Dispatches {@code event} to this subscriber using the proper executor. */
-  final void dispatchEvent(final Object event) {
+  final void dispatchEvent(Object event) {
     executor.execute(
-        new Runnable() {
-          @Override
-          public void run() {
-            try {
-              invokeSubscriberMethod(event);
-            } catch (InvocationTargetException e) {
-              bus.handleSubscriberException(e.getCause(), context(event));
-            }
+        () -> {
+          try {
+            invokeSubscriberMethod(event);
+          } catch (InvocationTargetException e) {
+            bus.handleSubscriberException(e.getCause(), context(event));
           }
         });
   }
@@ -108,7 +106,7 @@ public final int hashCode() {
   }
 
   @Override
-  public final boolean equals(@Nullable Object obj) {
+  public final boolean equals(@CheckForNull Object obj) {
     if (obj instanceof Subscriber) {
       Subscriber that = (Subscriber) obj;
       // Use == so that different equal instances will still receive events.
diff --git a/guava/src/com/google/common/eventbus/SubscriberExceptionContext.java b/guava/src/com/google/common/eventbus/SubscriberExceptionContext.java
index 6ddd86f21198..63c7d557fec9 100644
--- a/guava/src/com/google/common/eventbus/SubscriberExceptionContext.java
+++ b/guava/src/com/google/common/eventbus/SubscriberExceptionContext.java
@@ -23,6 +23,7 @@
  *
  * @since 16.0
  */
+@ElementTypesAreNonnullByDefault
 public class SubscriberExceptionContext {
   private final EventBus eventBus;
   private final Object event;
@@ -31,7 +32,7 @@ public class SubscriberExceptionContext {
 
   /**
    * @param eventBus The {@link EventBus} that handled the event and the subscriber. Useful for
-   *     broadcasting a a new event based on the error.
+   *     broadcasting a new event based on the error.
    * @param event The event object that caused the subscriber to throw.
    * @param subscriber The source subscriber context.
    * @param subscriberMethod the subscribed method.
@@ -46,7 +47,7 @@ public class SubscriberExceptionContext {
 
   /**
    * @return The {@link EventBus} that handled the event and the subscriber. Useful for broadcasting
-   *     a a new event based on the error.
+   *     a new event based on the error.
    */
   public EventBus getEventBus() {
     return eventBus;
diff --git a/guava/src/com/google/common/eventbus/SubscriberExceptionHandler.java b/guava/src/com/google/common/eventbus/SubscriberExceptionHandler.java
index c239ad74fc87..1c2fbb109adb 100644
--- a/guava/src/com/google/common/eventbus/SubscriberExceptionHandler.java
+++ b/guava/src/com/google/common/eventbus/SubscriberExceptionHandler.java
@@ -14,11 +14,13 @@
 
 package com.google.common.eventbus;
 
+
 /**
  * Handler for exceptions thrown by event subscribers.
  *
  * @since 16.0
  */
+@ElementTypesAreNonnullByDefault
 public interface SubscriberExceptionHandler {
   /** Handles exceptions thrown by subscribers. */
   void handleException(Throwable exception, SubscriberExceptionContext context);
diff --git a/guava/src/com/google/common/eventbus/SubscriberRegistry.java b/guava/src/com/google/common/eventbus/SubscriberRegistry.java
index 876af8bb6231..46e982016c55 100644
--- a/guava/src/com/google/common/eventbus/SubscriberRegistry.java
+++ b/guava/src/com/google/common/eventbus/SubscriberRegistry.java
@@ -46,13 +46,14 @@
 import java.util.Set;
 import java.util.concurrent.ConcurrentMap;
 import java.util.concurrent.CopyOnWriteArraySet;
-import org.checkerframework.checker.nullness.qual.Nullable;
+import javax.annotation.CheckForNull;
 
 /**
  * Registry of subscribers to a single event bus.
  *
  * @author Colin Decker
  */
+@ElementTypesAreNonnullByDefault
 final class SubscriberRegistry {
 
   /**
@@ -258,7 +259,7 @@ public int hashCode() {
     }
 
     @Override
-    public boolean equals(@Nullable Object o) {
+    public boolean equals(@CheckForNull Object o) {
       if (o instanceof MethodIdentifier) {
         MethodIdentifier ident = (MethodIdentifier) o;
         return name.equals(ident.name) && parameterTypes.equals(ident.parameterTypes);
diff --git a/guava/src/com/google/common/graph/AbstractBaseGraph.java b/guava/src/com/google/common/graph/AbstractBaseGraph.java
index 352df1995fbc..797468b7aa92 100644
--- a/guava/src/com/google/common/graph/AbstractBaseGraph.java
+++ b/guava/src/com/google/common/graph/AbstractBaseGraph.java
@@ -21,7 +21,6 @@
 import static com.google.common.base.Preconditions.checkState;
 import static com.google.common.graph.GraphConstants.ENDPOINTS_MISMATCH;
 
-import com.google.common.base.Function;
 import com.google.common.collect.ImmutableSet;
 import com.google.common.collect.Iterators;
 import com.google.common.collect.Sets;
@@ -30,7 +29,7 @@
 import com.google.common.primitives.Ints;
 import java.util.AbstractSet;
 import java.util.Set;
-import org.checkerframework.checker.nullness.qual.Nullable;
+import javax.annotation.CheckForNull;
 
 /**
  * This class provides a skeletal implementation of {@link BaseGraph}.
@@ -41,6 +40,7 @@
  * @author James Sexton
  * @param <N> Node parameter type
  */
+@ElementTypesAreNonnullByDefault
 abstract class AbstractBaseGraph<N> implements BaseGraph<N> {
 
   /**
@@ -76,7 +76,7 @@ public int size() {
       }
 
       @Override
-      public boolean remove(Object o) {
+      public boolean remove(@CheckForNull Object o) {
         throw new UnsupportedOperationException();
       }
 
@@ -85,7 +85,7 @@ public boolean remove(Object o) {
       // Graph<LinkedList>.
       @SuppressWarnings("unchecked")
       @Override
-      public boolean contains(@Nullable Object obj) {
+      public boolean contains(@CheckForNull Object obj) {
         if (!(obj instanceof EndpointPair)) {
           return false;
         }
@@ -114,31 +114,16 @@ public UnmodifiableIterator<EndpointPair<N>> iterator() {
               Iterators.concat(
                   Iterators.transform(
                       graph.predecessors(node).iterator(),
-                      new Function<N, EndpointPair<N>>() {
-                        @Override
-                        public EndpointPair<N> apply(N predecessor) {
-                          return EndpointPair.ordered(predecessor, node);
-                        }
-                      }),
+                      (N predecessor) -> EndpointPair.ordered(predecessor, node)),
                   Iterators.transform(
                       // filter out 'node' from successors (already covered by predecessors, above)
                       Sets.difference(graph.successors(node), ImmutableSet.of(node)).iterator(),
-                      new Function<N, EndpointPair<N>>() {
-                        @Override
-                        public EndpointPair<N> apply(N successor) {
-                          return EndpointPair.ordered(node, successor);
-                        }
-                      })));
+                      (N successor) -> EndpointPair.ordered(node, successor))));
         } else {
           return Iterators.unmodifiableIterator(
               Iterators.transform(
                   graph.adjacentNodes(node).iterator(),
-                  new Function<N, EndpointPair<N>>() {
-                    @Override
-                    public EndpointPair<N> apply(N adjacentNode) {
-                      return EndpointPair.unordered(node, adjacentNode);
-                    }
-                  }));
+                  (N adjacentNode) -> EndpointPair.unordered(node, adjacentNode)));
         }
       }
     };
diff --git a/guava/src/com/google/common/graph/AbstractDirectedNetworkConnections.java b/guava/src/com/google/common/graph/AbstractDirectedNetworkConnections.java
index 9afaf3eea799..ac452d4d610a 100644
--- a/guava/src/com/google/common/graph/AbstractDirectedNetworkConnections.java
+++ b/guava/src/com/google/common/graph/AbstractDirectedNetworkConnections.java
@@ -20,6 +20,7 @@
 import static com.google.common.base.Preconditions.checkState;
 import static com.google.common.graph.Graphs.checkNonNegative;
 import static com.google.common.graph.Graphs.checkPositive;
+import static java.util.Objects.requireNonNull;
 
 import com.google.common.collect.Iterables;
 import com.google.common.collect.Iterators;
@@ -30,7 +31,7 @@
 import java.util.Collections;
 import java.util.Map;
 import java.util.Set;
-import org.checkerframework.checker.nullness.qual.Nullable;
+import javax.annotation.CheckForNull;
 
 /**
  * A base implementation of {@link NetworkConnections} for directed networks.
@@ -39,17 +40,17 @@
  * @param <N> Node parameter type
  * @param <E> Edge parameter type
  */
+@ElementTypesAreNonnullByDefault
 abstract class AbstractDirectedNetworkConnections<N, E> implements NetworkConnections<N, E> {
   /** Keys are edges incoming to the origin node, values are the source node. */
-  protected final Map<E, N> inEdgeMap;
+  final Map<E, N> inEdgeMap;
 
   /** Keys are edges outgoing from the origin node, values are the target node. */
-  protected final Map<E, N> outEdgeMap;
+  final Map<E, N> outEdgeMap;
 
   private int selfLoopCount;
 
-  protected AbstractDirectedNetworkConnections(
-      Map<E, N> inEdgeMap, Map<E, N> outEdgeMap, int selfLoopCount) {
+  AbstractDirectedNetworkConnections(Map<E, N> inEdgeMap, Map<E, N> outEdgeMap, int selfLoopCount) {
     this.inEdgeMap = checkNotNull(inEdgeMap);
     this.outEdgeMap = checkNotNull(outEdgeMap);
     this.selfLoopCount = checkNonNegative(selfLoopCount);
@@ -79,7 +80,7 @@ public int size() {
       }
 
       @Override
-      public boolean contains(@Nullable Object obj) {
+      public boolean contains(@CheckForNull Object obj) {
         return inEdgeMap.containsKey(obj) || outEdgeMap.containsKey(obj);
       }
     };
@@ -99,7 +100,8 @@ public Set<E> outEdges() {
   public N adjacentNode(E edge) {
     // Since the reference node is defined to be 'source' for directed graphs,
     // we can assume this edge lives in the set of outgoing edges.
-    return checkNotNull(outEdgeMap.get(edge));
+    // (We're relying on callers to call this method only with an edge that's in the graph.)
+    return requireNonNull(outEdgeMap.get(edge));
   }
 
   @Override
@@ -108,13 +110,15 @@ public N removeInEdge(E edge, boolean isSelfLoop) {
       checkNonNegative(--selfLoopCount);
     }
     N previousNode = inEdgeMap.remove(edge);
-    return checkNotNull(previousNode);
+    // We're relying on callers to call this method only with an edge that's in the graph.
+    return requireNonNull(previousNode);
   }
 
   @Override
   public N removeOutEdge(E edge) {
     N previousNode = outEdgeMap.remove(edge);
-    return checkNotNull(previousNode);
+    // We're relying on callers to call this method only with an edge that's in the graph.
+    return requireNonNull(previousNode);
   }
 
   @Override
diff --git a/guava/src/com/google/common/graph/AbstractGraph.java b/guava/src/com/google/common/graph/AbstractGraph.java
index 986c94b91d82..9402be5d9360 100644
--- a/guava/src/com/google/common/graph/AbstractGraph.java
+++ b/guava/src/com/google/common/graph/AbstractGraph.java
@@ -17,7 +17,7 @@
 package com.google.common.graph;
 
 import com.google.common.annotations.Beta;
-import org.checkerframework.checker.nullness.qual.Nullable;
+import javax.annotation.CheckForNull;
 
 /**
  * This class provides a skeletal implementation of {@link Graph}. It is recommended to extend this
@@ -28,10 +28,11 @@
  * @since 20.0
  */
 @Beta
+@ElementTypesAreNonnullByDefault
 public abstract class AbstractGraph<N> extends AbstractBaseGraph<N> implements Graph<N> {
 
   @Override
-  public final boolean equals(@Nullable Object obj) {
+  public final boolean equals(@CheckForNull Object obj) {
     if (obj == this) {
       return true;
     }
diff --git a/guava/src/com/google/common/graph/AbstractGraphBuilder.java b/guava/src/com/google/common/graph/AbstractGraphBuilder.java
index 84e461a46c37..a4e1543f1d63 100644
--- a/guava/src/com/google/common/graph/AbstractGraphBuilder.java
+++ b/guava/src/com/google/common/graph/AbstractGraphBuilder.java
@@ -23,6 +23,7 @@
  *
  * @author James Sexton
  */
+@ElementTypesAreNonnullByDefault
 abstract class AbstractGraphBuilder<N> {
   final boolean directed;
   boolean allowsSelfLoops = false;
diff --git a/guava/src/com/google/common/graph/AbstractNetwork.java b/guava/src/com/google/common/graph/AbstractNetwork.java
index 648ee9bfa0de..d6bf4c36c6fe 100644
--- a/guava/src/com/google/common/graph/AbstractNetwork.java
+++ b/guava/src/com/google/common/graph/AbstractNetwork.java
@@ -35,7 +35,7 @@
 import java.util.Map;
 import java.util.Optional;
 import java.util.Set;
-import org.checkerframework.checker.nullness.qual.Nullable;
+import javax.annotation.CheckForNull;
 
 /**
  * This class provides a skeletal implementation of {@link Network}. It is recommended to extend
@@ -50,6 +50,7 @@
  * @since 20.0
  */
 @Beta
+@ElementTypesAreNonnullByDefault
 public abstract class AbstractNetwork<N, E> implements Network<N, E> {
 
   @Override
@@ -90,7 +91,7 @@ public int size() {
           // Network<LinkedList>.
           @SuppressWarnings("unchecked")
           @Override
-          public boolean contains(@Nullable Object obj) {
+          public boolean contains(@CheckForNull Object obj) {
             if (!(obj instanceof EndpointPair)) {
               return false;
             }
@@ -206,7 +207,8 @@ public Optional<E> edgeConnecting(EndpointPair<N> endpoints) {
   }
 
   @Override
-  public @Nullable E edgeConnectingOrNull(N nodeU, N nodeV) {
+  @CheckForNull
+  public E edgeConnectingOrNull(N nodeU, N nodeV) {
     Set<E> edgesConnecting = edgesConnecting(nodeU, nodeV);
     switch (edgesConnecting.size()) {
       case 0:
@@ -219,7 +221,8 @@ public Optional<E> edgeConnecting(EndpointPair<N> endpoints) {
   }
 
   @Override
-  public @Nullable E edgeConnectingOrNull(EndpointPair<N> endpoints) {
+  @CheckForNull
+  public E edgeConnectingOrNull(EndpointPair<N> endpoints) {
     validateEndpoints(endpoints);
     return edgeConnectingOrNull(endpoints.nodeU(), endpoints.nodeV());
   }
@@ -254,7 +257,7 @@ protected final boolean isOrderingCompatible(EndpointPair<?> endpoints) {
   }
 
   @Override
-  public final boolean equals(@Nullable Object obj) {
+  public final boolean equals(@CheckForNull Object obj) {
     if (obj == this) {
       return true;
     }
diff --git a/guava/src/com/google/common/graph/AbstractUndirectedNetworkConnections.java b/guava/src/com/google/common/graph/AbstractUndirectedNetworkConnections.java
index 03279d068ec0..8f736d7baa23 100644
--- a/guava/src/com/google/common/graph/AbstractUndirectedNetworkConnections.java
+++ b/guava/src/com/google/common/graph/AbstractUndirectedNetworkConnections.java
@@ -18,10 +18,12 @@
 
 import static com.google.common.base.Preconditions.checkNotNull;
 import static com.google.common.base.Preconditions.checkState;
+import static java.util.Objects.requireNonNull;
 
 import java.util.Collections;
 import java.util.Map;
 import java.util.Set;
+import javax.annotation.CheckForNull;
 
 /**
  * A base implementation of {@link NetworkConnections} for undirected networks.
@@ -30,11 +32,12 @@
  * @param <N> Node parameter type
  * @param <E> Edge parameter type
  */
+@ElementTypesAreNonnullByDefault
 abstract class AbstractUndirectedNetworkConnections<N, E> implements NetworkConnections<N, E> {
   /** Keys are edges incident to the origin node, values are the node at the other end. */
-  protected final Map<E, N> incidentEdgeMap;
+  final Map<E, N> incidentEdgeMap;
 
-  protected AbstractUndirectedNetworkConnections(Map<E, N> incidentEdgeMap) {
+  AbstractUndirectedNetworkConnections(Map<E, N> incidentEdgeMap) {
     this.incidentEdgeMap = checkNotNull(incidentEdgeMap);
   }
 
@@ -65,10 +68,12 @@ public Set<E> outEdges() {
 
   @Override
   public N adjacentNode(E edge) {
-    return checkNotNull(incidentEdgeMap.get(edge));
+    // We're relying on callers to call this method only with an edge that's in the graph.
+    return requireNonNull(incidentEdgeMap.get(edge));
   }
 
   @Override
+  @CheckForNull
   public N removeInEdge(E edge, boolean isSelfLoop) {
     if (!isSelfLoop) {
       return removeOutEdge(edge);
@@ -79,7 +84,8 @@ public N removeInEdge(E edge, boolean isSelfLoop) {
   @Override
   public N removeOutEdge(E edge) {
     N previousNode = incidentEdgeMap.remove(edge);
-    return checkNotNull(previousNode);
+    // We're relying on callers to call this method only with an edge that's in the graph.
+    return requireNonNull(previousNode);
   }
 
   @Override
diff --git a/guava/src/com/google/common/graph/AbstractValueGraph.java b/guava/src/com/google/common/graph/AbstractValueGraph.java
index c83cff585e32..5b8e520c35e8 100644
--- a/guava/src/com/google/common/graph/AbstractValueGraph.java
+++ b/guava/src/com/google/common/graph/AbstractValueGraph.java
@@ -16,13 +16,15 @@
 
 package com.google.common.graph;
 
+import static java.util.Objects.requireNonNull;
+
 import com.google.common.annotations.Beta;
 import com.google.common.base.Function;
 import com.google.common.collect.Maps;
 import java.util.Map;
 import java.util.Optional;
 import java.util.Set;
-import org.checkerframework.checker.nullness.qual.Nullable;
+import javax.annotation.CheckForNull;
 
 /**
  * This class provides a skeletal implementation of {@link ValueGraph}. It is recommended to extend
@@ -37,6 +39,7 @@
  * @since 20.0
  */
 @Beta
+@ElementTypesAreNonnullByDefault
 public abstract class AbstractValueGraph<N, V> extends AbstractBaseGraph<N>
     implements ValueGraph<N, V> {
 
@@ -116,7 +119,7 @@ public Optional<V> edgeValue(EndpointPair<N> endpoints) {
   }
 
   @Override
-  public final boolean equals(@Nullable Object obj) {
+  public final boolean equals(@CheckForNull Object obj) {
     if (obj == this) {
       return true;
     }
@@ -153,7 +156,8 @@ private static <N, V> Map<EndpointPair<N>, V> edgeValueMap(final ValueGraph<N, V
         new Function<EndpointPair<N>, V>() {
           @Override
           public V apply(EndpointPair<N> edge) {
-            return graph.edgeValueOrDefault(edge.nodeU(), edge.nodeV(), null);
+            // requireNonNull is safe because the endpoint pair comes from the graph.
+            return requireNonNull(graph.edgeValueOrDefault(edge.nodeU(), edge.nodeV(), null));
           }
         };
     return Maps.asMap(graph.edges(), edgeToValueFn);
diff --git a/guava/src/com/google/common/graph/BaseGraph.java b/guava/src/com/google/common/graph/BaseGraph.java
index 1df5de7f174e..68813e18a76d 100644
--- a/guava/src/com/google/common/graph/BaseGraph.java
+++ b/guava/src/com/google/common/graph/BaseGraph.java
@@ -24,6 +24,7 @@
  * @author James Sexton
  * @param <N> Node parameter type
  */
+@ElementTypesAreNonnullByDefault
 interface BaseGraph<N> extends SuccessorsFunction<N>, PredecessorsFunction<N> {
   //
   // Graph-level accessors
diff --git a/guava/src/com/google/common/graph/DirectedGraphConnections.java b/guava/src/com/google/common/graph/DirectedGraphConnections.java
index ac5d08961a20..0feb973f3f79 100644
--- a/guava/src/com/google/common/graph/DirectedGraphConnections.java
+++ b/guava/src/com/google/common/graph/DirectedGraphConnections.java
@@ -40,7 +40,7 @@
 import java.util.Map.Entry;
 import java.util.Set;
 import java.util.concurrent.atomic.AtomicBoolean;
-import org.checkerframework.checker.nullness.qual.Nullable;
+import javax.annotation.CheckForNull;
 
 /**
  * An implementation of {@link GraphConnections} for directed graphs.
@@ -50,6 +50,7 @@
  * @param <N> Node parameter type
  * @param <V> Value parameter type
  */
+@ElementTypesAreNonnullByDefault
 final class DirectedGraphConnections<N, V> implements GraphConnections<N, V> {
   /**
    * A wrapper class to indicate a node is both a predecessor and successor while still providing
@@ -82,7 +83,7 @@ static final class Pred<N> extends NodeConnection<N> {
       }
 
       @Override
-      public boolean equals(Object that) {
+      public boolean equals(@CheckForNull Object that) {
         if (that instanceof Pred) {
           return this.node.equals(((Pred<?>) that).node);
         } else {
@@ -103,7 +104,7 @@ static final class Succ<N> extends NodeConnection<N> {
       }
 
       @Override
-      public boolean equals(Object that) {
+      public boolean equals(@CheckForNull Object that) {
         if (that instanceof Succ) {
           return this.node.equals(((Succ<?>) that).node);
         } else {
@@ -133,14 +134,14 @@ public int hashCode() {
    * LinkedHashMap combines two such edges into a single node-value pair, even though the edges may
    * not have been inserted consecutively.
    */
-  private final @Nullable List<NodeConnection<N>> orderedNodeConnections;
+  @CheckForNull private final List<NodeConnection<N>> orderedNodeConnections;
 
   private int predecessorCount;
   private int successorCount;
 
   private DirectedGraphConnections(
       Map<N, Object> adjacentNodeValues,
-      @Nullable List<NodeConnection<N>> orderedNodeConnections,
+      @CheckForNull List<NodeConnection<N>> orderedNodeConnections,
       int predecessorCount,
       int successorCount) {
     this.adjacentNodeValues = checkNotNull(adjacentNodeValues);
@@ -162,13 +163,13 @@ static <N, V> DirectedGraphConnections<N, V> of(ElementOrder<N> incidentEdgeOrde
         orderedNodeConnections = null;
         break;
       case STABLE:
-        orderedNodeConnections = new ArrayList<NodeConnection<N>>();
+        orderedNodeConnections = new ArrayList<>();
         break;
       default:
         throw new AssertionError(incidentEdgeOrder.type());
     }
 
-    return new DirectedGraphConnections<N, V>(
+    return new DirectedGraphConnections<>(
         /* adjacentNodeValues = */ new HashMap<N, Object>(initialCapacity, INNER_LOAD_FACTOR),
         orderedNodeConnections,
         /* predecessorCount = */ 0,
@@ -238,10 +239,11 @@ public Set<N> adjacentNodes() {
       return new AbstractSet<N>() {
         @Override
         public UnmodifiableIterator<N> iterator() {
-          final Iterator<NodeConnection<N>> nodeConnections = orderedNodeConnections.iterator();
-          final Set<N> seenNodes = new HashSet<>();
+          Iterator<NodeConnection<N>> nodeConnections = orderedNodeConnections.iterator();
+          Set<N> seenNodes = new HashSet<>();
           return new AbstractIterator<N>() {
             @Override
+            @CheckForNull
             protected N computeNext() {
               while (nodeConnections.hasNext()) {
                 NodeConnection<N> nodeConnection = nodeConnections.next();
@@ -261,7 +263,7 @@ public int size() {
         }
 
         @Override
-        public boolean contains(@Nullable Object obj) {
+        public boolean contains(@CheckForNull Object obj) {
           return adjacentNodeValues.containsKey(obj);
         }
       };
@@ -274,9 +276,10 @@ public Set<N> predecessors() {
       @Override
       public UnmodifiableIterator<N> iterator() {
         if (orderedNodeConnections == null) {
-          final Iterator<Entry<N, Object>> entries = adjacentNodeValues.entrySet().iterator();
+          Iterator<Entry<N, Object>> entries = adjacentNodeValues.entrySet().iterator();
           return new AbstractIterator<N>() {
             @Override
+            @CheckForNull
             protected N computeNext() {
               while (entries.hasNext()) {
                 Entry<N, Object> entry = entries.next();
@@ -288,9 +291,10 @@ protected N computeNext() {
             }
           };
         } else {
-          final Iterator<NodeConnection<N>> nodeConnections = orderedNodeConnections.iterator();
+          Iterator<NodeConnection<N>> nodeConnections = orderedNodeConnections.iterator();
           return new AbstractIterator<N>() {
             @Override
+            @CheckForNull
             protected N computeNext() {
               while (nodeConnections.hasNext()) {
                 NodeConnection<N> nodeConnection = nodeConnections.next();
@@ -310,7 +314,7 @@ public int size() {
       }
 
       @Override
-      public boolean contains(@Nullable Object obj) {
+      public boolean contains(@CheckForNull Object obj) {
         return isPredecessor(adjacentNodeValues.get(obj));
       }
     };
@@ -322,9 +326,10 @@ public Set<N> successors() {
       @Override
       public UnmodifiableIterator<N> iterator() {
         if (orderedNodeConnections == null) {
-          final Iterator<Entry<N, Object>> entries = adjacentNodeValues.entrySet().iterator();
+          Iterator<Entry<N, Object>> entries = adjacentNodeValues.entrySet().iterator();
           return new AbstractIterator<N>() {
             @Override
+            @CheckForNull
             protected N computeNext() {
               while (entries.hasNext()) {
                 Entry<N, Object> entry = entries.next();
@@ -336,9 +341,10 @@ protected N computeNext() {
             }
           };
         } else {
-          final Iterator<NodeConnection<N>> nodeConnections = orderedNodeConnections.iterator();
+          Iterator<NodeConnection<N>> nodeConnections = orderedNodeConnections.iterator();
           return new AbstractIterator<N>() {
             @Override
+            @CheckForNull
             protected N computeNext() {
               while (nodeConnections.hasNext()) {
                 NodeConnection<N> nodeConnection = nodeConnections.next();
@@ -358,55 +364,43 @@ public int size() {
       }
 
       @Override
-      public boolean contains(@Nullable Object obj) {
+      public boolean contains(@CheckForNull Object obj) {
         return isSuccessor(adjacentNodeValues.get(obj));
       }
     };
   }
 
   @Override
-  public Iterator<EndpointPair<N>> incidentEdgeIterator(final N thisNode) {
+  public Iterator<EndpointPair<N>> incidentEdgeIterator(N thisNode) {
     checkNotNull(thisNode);
 
-    final Iterator<EndpointPair<N>> resultWithDoubleSelfLoop;
+    Iterator<EndpointPair<N>> resultWithDoubleSelfLoop;
     if (orderedNodeConnections == null) {
       resultWithDoubleSelfLoop =
           Iterators.concat(
               Iterators.transform(
                   predecessors().iterator(),
-                  new Function<N, EndpointPair<N>>() {
-                    @Override
-                    public EndpointPair<N> apply(N predecessor) {
-                      return EndpointPair.ordered(predecessor, thisNode);
-                    }
-                  }),
+                  (N predecessor) -> EndpointPair.ordered(predecessor, thisNode)),
               Iterators.transform(
                   successors().iterator(),
-                  new Function<N, EndpointPair<N>>() {
-                    @Override
-                    public EndpointPair<N> apply(N successor) {
-                      return EndpointPair.ordered(thisNode, successor);
-                    }
-                  }));
+                  (N successor) -> EndpointPair.ordered(thisNode, successor)));
     } else {
       resultWithDoubleSelfLoop =
           Iterators.transform(
               orderedNodeConnections.iterator(),
-              new Function<NodeConnection<N>, EndpointPair<N>>() {
-                @Override
-                public EndpointPair<N> apply(NodeConnection<N> connection) {
-                  if (connection instanceof NodeConnection.Succ) {
-                    return EndpointPair.ordered(thisNode, connection.node);
-                  } else {
-                    return EndpointPair.ordered(connection.node, thisNode);
-                  }
+              (NodeConnection<N> connection) -> {
+                if (connection instanceof NodeConnection.Succ) {
+                  return EndpointPair.ordered(thisNode, connection.node);
+                } else {
+                  return EndpointPair.ordered(connection.node, thisNode);
                 }
               });
     }
 
-    final AtomicBoolean alreadySeenSelfLoop = new AtomicBoolean(false);
+    AtomicBoolean alreadySeenSelfLoop = new AtomicBoolean(false);
     return new AbstractIterator<EndpointPair<N>>() {
       @Override
+      @CheckForNull
       protected EndpointPair<N> computeNext() {
         while (resultWithDoubleSelfLoop.hasNext()) {
           EndpointPair<N> edge = resultWithDoubleSelfLoop.next();
@@ -425,6 +419,7 @@ protected EndpointPair<N> computeNext() {
 
   @SuppressWarnings("unchecked")
   @Override
+  @CheckForNull
   public V value(N node) {
     checkNotNull(node);
     Object value = adjacentNodeValues.get(node);
@@ -466,6 +461,7 @@ public void removePredecessor(N node) {
 
   @SuppressWarnings("unchecked")
   @Override
+  @CheckForNull
   public V removeSuccessor(Object node) {
     checkNotNull(node);
     Object previousValue = adjacentNodeValues.get(node);
@@ -489,7 +485,14 @@ public V removeSuccessor(Object node) {
       }
     }
 
-    return (V) removedValue;
+    /*
+     * TODO(cpovirk): `return (V) removedValue` once our checker permits that.
+     *
+     * (We promoted a class of warnings into errors because sometimes they indicate real problems.
+     * But now we need to "undo" some instance of spurious errors, as discussed in
+     * https://github.com/jspecify/checker-framework/issues/8.)
+     */
+    return removedValue == null ? null : (V) removedValue;
   }
 
   @Override
@@ -522,6 +525,7 @@ public void addPredecessor(N node, V unused) {
 
   @SuppressWarnings("unchecked")
   @Override
+  @CheckForNull
   public V addSuccessor(N node, V value) {
     Object previousValue = adjacentNodeValues.put(node, value);
     Object previousSuccessor;
@@ -546,14 +550,15 @@ public V addSuccessor(N node, V value) {
       }
     }
 
-    return (V) previousSuccessor;
+    // See the comment on the similar cast in removeSuccessor.
+    return previousSuccessor == null ? null : (V) previousSuccessor;
   }
 
-  private static boolean isPredecessor(@Nullable Object value) {
+  private static boolean isPredecessor(@CheckForNull Object value) {
     return (value == PRED) || (value instanceof PredAndSucc);
   }
 
-  private static boolean isSuccessor(@Nullable Object value) {
+  private static boolean isSuccessor(@CheckForNull Object value) {
     return (value != PRED) && (value != null);
   }
 }
diff --git a/guava/src/com/google/common/graph/DirectedMultiNetworkConnections.java b/guava/src/com/google/common/graph/DirectedMultiNetworkConnections.java
index 4a560aefbd1f..bd0e546f26e3 100644
--- a/guava/src/com/google/common/graph/DirectedMultiNetworkConnections.java
+++ b/guava/src/com/google/common/graph/DirectedMultiNetworkConnections.java
@@ -30,7 +30,7 @@
 import java.util.HashMap;
 import java.util.Map;
 import java.util.Set;
-import org.checkerframework.checker.nullness.qual.Nullable;
+import javax.annotation.CheckForNull;
 
 /**
  * An implementation of {@link NetworkConnections} for directed networks with parallel edges.
@@ -39,6 +39,7 @@
  * @param <N> Node parameter type
  * @param <E> Edge parameter type
  */
+@ElementTypesAreNonnullByDefault
 final class DirectedMultiNetworkConnections<N, E> extends AbstractDirectedNetworkConnections<N, E> {
 
   private DirectedMultiNetworkConnections(
@@ -59,7 +60,7 @@ static <N, E> DirectedMultiNetworkConnections<N, E> ofImmutable(
         ImmutableMap.copyOf(inEdges), ImmutableMap.copyOf(outEdges), selfLoopCount);
   }
 
-  @LazyInit private transient Reference<Multiset<N>> predecessorsReference;
+  @CheckForNull @LazyInit private transient Reference<Multiset<N>> predecessorsReference;
 
   @Override
   public Set<N> predecessors() {
@@ -75,7 +76,7 @@ private Multiset<N> predecessorsMultiset() {
     return predecessors;
   }
 
-  @LazyInit private transient Reference<Multiset<N>> successorsReference;
+  @CheckForNull @LazyInit private transient Reference<Multiset<N>> successorsReference;
 
   @Override
   public Set<N> successors() {
@@ -92,7 +93,7 @@ private Multiset<N> successorsMultiset() {
   }
 
   @Override
-  public Set<E> edgesConnecting(final N node) {
+  public Set<E> edgesConnecting(N node) {
     return new MultiEdgesConnecting<E>(outEdgeMap, node) {
       @Override
       public int size() {
@@ -139,7 +140,8 @@ public void addOutEdge(E edge, N node) {
     }
   }
 
-  private static <T> @Nullable T getReference(@Nullable Reference<T> reference) {
+  @CheckForNull
+  private static <T> T getReference(@CheckForNull Reference<T> reference) {
     return (reference == null) ? null : reference.get();
   }
 }
diff --git a/guava/src/com/google/common/graph/DirectedNetworkConnections.java b/guava/src/com/google/common/graph/DirectedNetworkConnections.java
index 2a0b010d0998..e1db65708eb0 100644
--- a/guava/src/com/google/common/graph/DirectedNetworkConnections.java
+++ b/guava/src/com/google/common/graph/DirectedNetworkConnections.java
@@ -32,10 +32,10 @@
  * @param <N> Node parameter type
  * @param <E> Edge parameter type
  */
+@ElementTypesAreNonnullByDefault
 final class DirectedNetworkConnections<N, E> extends AbstractDirectedNetworkConnections<N, E> {
 
-  protected DirectedNetworkConnections(
-      Map<E, N> inEdgeMap, Map<E, N> outEdgeMap, int selfLoopCount) {
+  DirectedNetworkConnections(Map<E, N> inEdgeMap, Map<E, N> outEdgeMap, int selfLoopCount) {
     super(inEdgeMap, outEdgeMap, selfLoopCount);
   }
 
@@ -62,6 +62,6 @@ public Set<N> successors() {
 
   @Override
   public Set<E> edgesConnecting(N node) {
-    return new EdgesConnecting<E>(((BiMap<E, N>) outEdgeMap).inverse(), node);
+    return new EdgesConnecting<>(((BiMap<E, N>) outEdgeMap).inverse(), node);
   }
 }
diff --git a/guava/src/com/google/common/graph/EdgesConnecting.java b/guava/src/com/google/common/graph/EdgesConnecting.java
index 1c4673544238..797970ba29c1 100644
--- a/guava/src/com/google/common/graph/EdgesConnecting.java
+++ b/guava/src/com/google/common/graph/EdgesConnecting.java
@@ -23,7 +23,7 @@
 import com.google.common.collect.UnmodifiableIterator;
 import java.util.AbstractSet;
 import java.util.Map;
-import org.checkerframework.checker.nullness.qual.Nullable;
+import javax.annotation.CheckForNull;
 
 /**
  * A class to represent the set of edges connecting an (implicit) origin node to a target node.
@@ -34,6 +34,7 @@
  * @author James Sexton
  * @param <E> Edge parameter type
  */
+@ElementTypesAreNonnullByDefault
 final class EdgesConnecting<E> extends AbstractSet<E> {
 
   private final Map<?, E> nodeToOutEdge;
@@ -58,12 +59,13 @@ public int size() {
   }
 
   @Override
-  public boolean contains(@Nullable Object edge) {
+  public boolean contains(@CheckForNull Object edge) {
     E connectingEdge = getConnectingEdge();
     return (connectingEdge != null && connectingEdge.equals(edge));
   }
 
-  private @Nullable E getConnectingEdge() {
+  @CheckForNull
+  private E getConnectingEdge() {
     return nodeToOutEdge.get(targetNode);
   }
 }
diff --git a/guava/src/com/google/common/graph/ElementOrder.java b/guava/src/com/google/common/graph/ElementOrder.java
index 257bdd653c52..b5985a280b86 100644
--- a/guava/src/com/google/common/graph/ElementOrder.java
+++ b/guava/src/com/google/common/graph/ElementOrder.java
@@ -28,7 +28,7 @@
 import com.google.errorprone.annotations.Immutable;
 import java.util.Comparator;
 import java.util.Map;
-import org.checkerframework.checker.nullness.qual.Nullable;
+import javax.annotation.CheckForNull;
 
 /**
  * Used to represent the order of elements in a data structure that supports different options for
@@ -46,11 +46,13 @@
  */
 @Beta
 @Immutable
+@ElementTypesAreNonnullByDefault
 public final class ElementOrder<T> {
   private final Type type;
 
   @SuppressWarnings("Immutable") // Hopefully the comparator provided is immutable!
-  private final @Nullable Comparator<T> comparator;
+  @CheckForNull
+  private final Comparator<T> comparator;
 
   /**
    * The type of ordering that this object specifies.
@@ -70,7 +72,7 @@ public enum Type {
     SORTED
   }
 
-  private ElementOrder(Type type, @Nullable Comparator<T> comparator) {
+  private ElementOrder(Type type, @CheckForNull Comparator<T> comparator) {
     this.type = checkNotNull(type);
     this.comparator = comparator;
     checkState((type == Type.SORTED) == (comparator != null));
@@ -78,7 +80,7 @@ private ElementOrder(Type type, @Nullable Comparator<T> comparator) {
 
   /** Returns an instance which specifies that no ordering is guaranteed. */
   public static <S> ElementOrder<S> unordered() {
-    return new ElementOrder<S>(Type.UNORDERED, null);
+    return new ElementOrder<>(Type.UNORDERED, null);
   }
 
   /**
@@ -118,19 +120,19 @@ public static <S> ElementOrder<S> unordered() {
    * @since 29.0
    */
   public static <S> ElementOrder<S> stable() {
-    return new ElementOrder<S>(Type.STABLE, null);
+    return new ElementOrder<>(Type.STABLE, null);
   }
 
   /** Returns an instance which specifies that insertion ordering is guaranteed. */
   public static <S> ElementOrder<S> insertion() {
-    return new ElementOrder<S>(Type.INSERTION, null);
+    return new ElementOrder<>(Type.INSERTION, null);
   }
 
   /**
    * Returns an instance which specifies that the natural ordering of the elements is guaranteed.
    */
   public static <S extends Comparable<? super S>> ElementOrder<S> natural() {
-    return new ElementOrder<S>(Type.SORTED, Ordering.<S>natural());
+    return new ElementOrder<>(Type.SORTED, Ordering.<S>natural());
   }
 
   /**
@@ -138,7 +140,7 @@ public static <S extends Comparable<? super S>> ElementOrder<S> natural() {
    * determined by {@code comparator}.
    */
   public static <S> ElementOrder<S> sorted(Comparator<S> comparator) {
-    return new ElementOrder<S>(Type.SORTED, checkNotNull(comparator));
+    return new ElementOrder<>(Type.SORTED, checkNotNull(comparator));
   }
 
   /** Returns the type of ordering used. */
@@ -159,7 +161,7 @@ public Comparator<T> comparator() {
   }
 
   @Override
-  public boolean equals(@Nullable Object obj) {
+  public boolean equals(@CheckForNull Object obj) {
     if (obj == this) {
       return true;
     }
diff --git a/guava/src/com/google/common/graph/ElementTypesAreNonnullByDefault.java b/guava/src/com/google/common/graph/ElementTypesAreNonnullByDefault.java
new file mode 100644
index 000000000000..0798de0c9883
--- /dev/null
+++ b/guava/src/com/google/common/graph/ElementTypesAreNonnullByDefault.java
@@ -0,0 +1,41 @@
+/*
+ * Copyright (C) 2021 The Guava Authors
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package com.google.common.graph;
+
+import static java.lang.annotation.ElementType.FIELD;
+import static java.lang.annotation.ElementType.METHOD;
+import static java.lang.annotation.ElementType.PARAMETER;
+import static java.lang.annotation.ElementType.TYPE;
+import static java.lang.annotation.RetentionPolicy.RUNTIME;
+
+import com.google.common.annotations.GwtCompatible;
+import java.lang.annotation.Retention;
+import java.lang.annotation.Target;
+import javax.annotation.Nonnull;
+import javax.annotation.meta.TypeQualifierDefault;
+
+/**
+ * Marks all "top-level" types as non-null in a way that is recognized by Kotlin. Note that this
+ * unfortunately includes type-variable usages, so we also provide {@link ParametricNullness} to
+ * "undo" it as best we can.
+ */
+@GwtCompatible
+@Retention(RUNTIME)
+@Target(TYPE)
+@TypeQualifierDefault({FIELD, METHOD, PARAMETER})
+@Nonnull
+@interface ElementTypesAreNonnullByDefault {}
diff --git a/guava/src/com/google/common/graph/EndpointPair.java b/guava/src/com/google/common/graph/EndpointPair.java
index c87663474188..fe2397c6b97b 100644
--- a/guava/src/com/google/common/graph/EndpointPair.java
+++ b/guava/src/com/google/common/graph/EndpointPair.java
@@ -24,7 +24,7 @@
 import com.google.common.collect.Iterators;
 import com.google.common.collect.UnmodifiableIterator;
 import com.google.errorprone.annotations.Immutable;
-import org.checkerframework.checker.nullness.qual.Nullable;
+import javax.annotation.CheckForNull;
 
 /**
  * An immutable pair representing the two endpoints of an edge in a graph. The {@link EndpointPair}
@@ -39,6 +39,7 @@
  */
 @Beta
 @Immutable(containerOf = {"N"})
+@ElementTypesAreNonnullByDefault
 public abstract class EndpointPair<N> implements Iterable<N> {
   private final N nodeU;
   private final N nodeV;
@@ -50,13 +51,13 @@ private EndpointPair(N nodeU, N nodeV) {
 
   /** Returns an {@link EndpointPair} representing the endpoints of a directed edge. */
   public static <N> EndpointPair<N> ordered(N source, N target) {
-    return new Ordered<N>(source, target);
+    return new Ordered<>(source, target);
   }
 
   /** Returns an {@link EndpointPair} representing the endpoints of an undirected edge. */
   public static <N> EndpointPair<N> unordered(N nodeU, N nodeV) {
     // Swap nodes on purpose to prevent callers from relying on the "ordering" of an unordered pair.
-    return new Unordered<N>(nodeV, nodeU);
+    return new Unordered<>(nodeV, nodeU);
   }
 
   /** Returns an {@link EndpointPair} representing the endpoints of an edge in {@code graph}. */
@@ -103,8 +104,9 @@ public final N nodeV() {
    * Returns the node that is adjacent to {@code node} along the origin edge.
    *
    * @throws IllegalArgumentException if this {@link EndpointPair} does not contain {@code node}
+   * @since 20.0 (but the argument type was changed from {@code Object} to {@code N} in 31.0)
    */
-  public final N adjacentNode(Object node) {
+  public final N adjacentNode(N node) {
     if (node.equals(nodeU)) {
       return nodeV;
     } else if (node.equals(nodeV)) {
@@ -132,7 +134,7 @@ public final UnmodifiableIterator<N> iterator() {
    * ordered {@link EndpointPair} is never equal to an unordered {@link EndpointPair}.
    */
   @Override
-  public abstract boolean equals(@Nullable Object obj);
+  public abstract boolean equals(@CheckForNull Object obj);
 
   /**
    * The hashcode of an ordered {@link EndpointPair} is equal to {@code Objects.hashCode(source(),
@@ -163,7 +165,7 @@ public boolean isOrdered() {
     }
 
     @Override
-    public boolean equals(@Nullable Object obj) {
+    public boolean equals(@CheckForNull Object obj) {
       if (obj == this) {
         return true;
       }
@@ -211,7 +213,7 @@ public boolean isOrdered() {
     }
 
     @Override
-    public boolean equals(@Nullable Object obj) {
+    public boolean equals(@CheckForNull Object obj) {
       if (obj == this) {
         return true;
       }
diff --git a/guava/src/com/google/common/graph/EndpointPairIterator.java b/guava/src/com/google/common/graph/EndpointPairIterator.java
index c4e6e073e93d..7096dbe3da2a 100644
--- a/guava/src/com/google/common/graph/EndpointPairIterator.java
+++ b/guava/src/com/google/common/graph/EndpointPairIterator.java
@@ -17,24 +17,30 @@
 package com.google.common.graph;
 
 import static com.google.common.base.Preconditions.checkState;
+import static java.util.Objects.requireNonNull;
 
 import com.google.common.collect.AbstractIterator;
 import com.google.common.collect.ImmutableSet;
 import com.google.common.collect.Sets;
 import java.util.Iterator;
 import java.util.Set;
+import javax.annotation.CheckForNull;
+import org.checkerframework.checker.nullness.qual.Nullable;
 
 /**
  * A class to facilitate the set returned by {@link Graph#edges()}.
  *
  * @author James Sexton
  */
+@ElementTypesAreNonnullByDefault
 abstract class EndpointPairIterator<N> extends AbstractIterator<EndpointPair<N>> {
   private final BaseGraph<N> graph;
   private final Iterator<N> nodeIterator;
 
-  protected N node = null; // null is safe as an initial value because graphs don't allow null nodes
-  protected Iterator<N> successorIterator = ImmutableSet.<N>of().iterator();
+  @CheckForNull
+  N node = null; // null is safe as an initial value because graphs don't allow null nodes
+
+  Iterator<N> successorIterator = ImmutableSet.<N>of().iterator();
 
   static <N> EndpointPairIterator<N> of(BaseGraph<N> graph) {
     return graph.isDirected() ? new Directed<N>(graph) : new Undirected<N>(graph);
@@ -49,7 +55,7 @@ private EndpointPairIterator(BaseGraph<N> graph) {
    * Called after {@link #successorIterator} is exhausted. Advances {@link #node} to the next node
    * and updates {@link #successorIterator} to iterate through the successors of {@link #node}.
    */
-  protected final boolean advance() {
+  final boolean advance() {
     checkState(!successorIterator.hasNext());
     if (!nodeIterator.hasNext()) {
       return false;
@@ -69,10 +75,12 @@ private Directed(BaseGraph<N> graph) {
     }
 
     @Override
+    @CheckForNull
     protected EndpointPair<N> computeNext() {
       while (true) {
         if (successorIterator.hasNext()) {
-          return EndpointPair.ordered(node, successorIterator.next());
+          // requireNonNull is safe because successorIterator is empty until we set this.node.
+          return EndpointPair.ordered(requireNonNull(node), successorIterator.next());
         }
         if (!advance()) {
           return endOfData();
@@ -108,20 +116,28 @@ protected EndpointPair<N> computeNext() {
    * </pre>
    */
   private static final class Undirected<N> extends EndpointPairIterator<N> {
-    private Set<N> visitedNodes;
+    // It's a little weird that we add `null` to this set, but it makes for slightly simpler code.
+    @CheckForNull private Set<@Nullable N> visitedNodes;
 
     private Undirected(BaseGraph<N> graph) {
       super(graph);
-      this.visitedNodes = Sets.newHashSetWithExpectedSize(graph.nodes().size());
+      this.visitedNodes = Sets.newHashSetWithExpectedSize(graph.nodes().size() + 1);
     }
 
     @Override
+    @CheckForNull
     protected EndpointPair<N> computeNext() {
       while (true) {
+        /*
+         * requireNonNull is safe because visitedNodes isn't cleared until this method calls
+         * endOfData() (after which this method is never called again).
+         */
+        requireNonNull(visitedNodes);
         while (successorIterator.hasNext()) {
           N otherNode = successorIterator.next();
           if (!visitedNodes.contains(otherNode)) {
-            return EndpointPair.unordered(node, otherNode);
+            // requireNonNull is safe because successorIterator is empty until we set node.
+            return EndpointPair.unordered(requireNonNull(node), otherNode);
           }
         }
         // Add to visited set *after* processing neighbors so we still include self-loops.
diff --git a/guava/src/com/google/common/graph/ForwardingGraph.java b/guava/src/com/google/common/graph/ForwardingGraph.java
index 4a3ab8c77b3b..f4ddf425db29 100644
--- a/guava/src/com/google/common/graph/ForwardingGraph.java
+++ b/guava/src/com/google/common/graph/ForwardingGraph.java
@@ -24,9 +24,10 @@
  *
  * @author James Sexton
  */
+@ElementTypesAreNonnullByDefault
 abstract class ForwardingGraph<N> extends AbstractGraph<N> {
 
-  protected abstract BaseGraph<N> delegate();
+  abstract BaseGraph<N> delegate();
 
   @Override
   public Set<N> nodes() {
diff --git a/guava/src/com/google/common/graph/ForwardingNetwork.java b/guava/src/com/google/common/graph/ForwardingNetwork.java
index 76347b17a7a0..9f1c6e7702e8 100644
--- a/guava/src/com/google/common/graph/ForwardingNetwork.java
+++ b/guava/src/com/google/common/graph/ForwardingNetwork.java
@@ -18,6 +18,7 @@
 
 import java.util.Optional;
 import java.util.Set;
+import javax.annotation.CheckForNull;
 
 /**
  * A class to allow {@link Network} implementations to be backed by a provided delegate. This is not
@@ -26,9 +27,10 @@
  * @author James Sexton
  * @author Joshua O'Madadhain
  */
+@ElementTypesAreNonnullByDefault
 abstract class ForwardingNetwork<N, E> extends AbstractNetwork<N, E> {
 
-  protected abstract Network<N, E> delegate();
+  abstract Network<N, E> delegate();
 
   @Override
   public Set<N> nodes() {
@@ -141,11 +143,13 @@ public Optional<E> edgeConnecting(EndpointPair<N> endpoints) {
   }
 
   @Override
+  @CheckForNull
   public E edgeConnectingOrNull(N nodeU, N nodeV) {
     return delegate().edgeConnectingOrNull(nodeU, nodeV);
   }
 
   @Override
+  @CheckForNull
   public E edgeConnectingOrNull(EndpointPair<N> endpoints) {
     return delegate().edgeConnectingOrNull(endpoints);
   }
diff --git a/guava/src/com/google/common/graph/ForwardingValueGraph.java b/guava/src/com/google/common/graph/ForwardingValueGraph.java
index 8db773f923ef..fcd5d28bc394 100644
--- a/guava/src/com/google/common/graph/ForwardingValueGraph.java
+++ b/guava/src/com/google/common/graph/ForwardingValueGraph.java
@@ -18,7 +18,7 @@
 
 import java.util.Optional;
 import java.util.Set;
-import org.checkerframework.checker.nullness.qual.Nullable;
+import javax.annotation.CheckForNull;
 
 /**
  * A class to allow {@link ValueGraph} implementations to be backed by a provided delegate. This is
@@ -27,9 +27,10 @@
  * @author James Sexton
  * @author Joshua O'Madadhain
  */
+@ElementTypesAreNonnullByDefault
 abstract class ForwardingValueGraph<N, V> extends AbstractValueGraph<N, V> {
 
-  protected abstract ValueGraph<N, V> delegate();
+  abstract ValueGraph<N, V> delegate();
 
   @Override
   public Set<N> nodes() {
@@ -116,12 +117,14 @@ public Optional<V> edgeValue(EndpointPair<N> endpoints) {
   }
 
   @Override
-  public @Nullable V edgeValueOrDefault(N nodeU, N nodeV, @Nullable V defaultValue) {
+  @CheckForNull
+  public V edgeValueOrDefault(N nodeU, N nodeV, @CheckForNull V defaultValue) {
     return delegate().edgeValueOrDefault(nodeU, nodeV, defaultValue);
   }
 
   @Override
-  public @Nullable V edgeValueOrDefault(EndpointPair<N> endpoints, @Nullable V defaultValue) {
+  @CheckForNull
+  public V edgeValueOrDefault(EndpointPair<N> endpoints, @CheckForNull V defaultValue) {
     return delegate().edgeValueOrDefault(endpoints, defaultValue);
   }
 }
diff --git a/guava/src/com/google/common/graph/Graph.java b/guava/src/com/google/common/graph/Graph.java
index 84f9695c45ae..5dc0e71faf6d 100644
--- a/guava/src/com/google/common/graph/Graph.java
+++ b/guava/src/com/google/common/graph/Graph.java
@@ -20,7 +20,7 @@
 import com.google.errorprone.annotations.DoNotMock;
 import java.util.Collection;
 import java.util.Set;
-import org.checkerframework.checker.nullness.qual.Nullable;
+import javax.annotation.CheckForNull;
 
 /**
  * An interface for <a
@@ -103,6 +103,7 @@
  */
 @Beta
 @DoNotMock("Use GraphBuilder to create a real instance")
+@ElementTypesAreNonnullByDefault
 public interface Graph<N> extends BaseGraph<N> {
   //
   // Graph-level accessors
@@ -289,7 +290,7 @@ public interface Graph<N> extends BaseGraph<N> {
    * <p>A reference implementation of this is provided by {@link AbstractGraph#equals(Object)}.
    */
   @Override
-  boolean equals(@Nullable Object object);
+  boolean equals(@CheckForNull Object object);
 
   /**
    * Returns the hash code for this graph. The hash code of a graph is defined as the hash code of
diff --git a/guava/src/com/google/common/graph/GraphBuilder.java b/guava/src/com/google/common/graph/GraphBuilder.java
index f00d7b1f93be..8c0871b467d1 100644
--- a/guava/src/com/google/common/graph/GraphBuilder.java
+++ b/guava/src/com/google/common/graph/GraphBuilder.java
@@ -64,6 +64,7 @@
  */
 @Beta
 @DoNotMock
+@ElementTypesAreNonnullByDefault
 public final class GraphBuilder<N> extends AbstractGraphBuilder<N> {
 
   /** Creates a new instance with the specified edge directionality. */
@@ -170,7 +171,7 @@ public <N1 extends N> GraphBuilder<N1> incidentEdgeOrder(ElementOrder<N1> incide
 
   /** Returns an empty {@link MutableGraph} with the properties of this {@link GraphBuilder}. */
   public <N1 extends N> MutableGraph<N1> build() {
-    return new StandardMutableGraph<N1>(this);
+    return new StandardMutableGraph<>(this);
   }
 
   GraphBuilder<N> copy() {
diff --git a/guava/src/com/google/common/graph/GraphConnections.java b/guava/src/com/google/common/graph/GraphConnections.java
index bed5508a1c8e..7d4f8f0cf02b 100644
--- a/guava/src/com/google/common/graph/GraphConnections.java
+++ b/guava/src/com/google/common/graph/GraphConnections.java
@@ -19,7 +19,7 @@
 import com.google.errorprone.annotations.CanIgnoreReturnValue;
 import java.util.Iterator;
 import java.util.Set;
-import org.checkerframework.checker.nullness.qual.Nullable;
+import javax.annotation.CheckForNull;
 
 /**
  * An interface for representing and manipulating an origin node's adjacent nodes and edge values in
@@ -29,6 +29,7 @@
  * @param <N> Node parameter type
  * @param <V> Value parameter type
  */
+@ElementTypesAreNonnullByDefault
 interface GraphConnections<N, V> {
 
   Set<N> adjacentNodes();
@@ -48,7 +49,7 @@ interface GraphConnections<N, V> {
    * Returns the value associated with the edge connecting the origin node to {@code node}, or null
    * if there is no such edge.
    */
-  @Nullable
+  @CheckForNull
   V value(N node);
 
   /** Remove {@code node} from the set of predecessors. */
@@ -59,6 +60,7 @@ interface GraphConnections<N, V> {
    * the edge connecting the two nodes.
    */
   @CanIgnoreReturnValue
+  @CheckForNull
   V removeSuccessor(N node);
 
   /**
@@ -73,5 +75,6 @@ interface GraphConnections<N, V> {
    * the value previously associated with the edge connecting the two nodes.
    */
   @CanIgnoreReturnValue
+  @CheckForNull
   V addSuccessor(N node, V value);
 }
diff --git a/guava/src/com/google/common/graph/GraphConstants.java b/guava/src/com/google/common/graph/GraphConstants.java
index 224c6d2486f7..25ad455212c7 100644
--- a/guava/src/com/google/common/graph/GraphConstants.java
+++ b/guava/src/com/google/common/graph/GraphConstants.java
@@ -16,7 +16,11 @@
 
 package com.google.common.graph;
 
+import org.checkerframework.checker.formatter.qual.ConversionCategory;
+import org.checkerframework.checker.formatter.qual.Format;
+
 /** A utility class to hold various constants used by the Guava Graph library. */
+@ElementTypesAreNonnullByDefault
 final class GraphConstants {
 
   private GraphConstants() {}
@@ -31,12 +35,12 @@ private GraphConstants() {}
   static final int INNER_CAPACITY = 2; // ceiling(EXPECTED_DEGREE / INNER_LOAD_FACTOR)
 
   // Error messages
-  static final String NODE_NOT_IN_GRAPH = "Node %s is not an element of this graph.";
-  static final String EDGE_NOT_IN_GRAPH = "Edge %s is not an element of this graph.";
+  static final @Format({ConversionCategory.GENERAL}) String NODE_NOT_IN_GRAPH = "Node %s is not an element of this graph.";
+  static final @Format({ConversionCategory.GENERAL}) String EDGE_NOT_IN_GRAPH = "Edge %s is not an element of this graph.";
   static final String REUSING_EDGE =
       "Edge %s already exists between the following nodes: %s, "
           + "so it cannot be reused to connect the following nodes: %s.";
-  static final String MULTIPLE_EDGES_CONNECTING =
+  static final @Format({ConversionCategory.GENERAL, ConversionCategory.GENERAL}) String MULTIPLE_EDGES_CONNECTING =
       "Cannot call edgeConnecting() when parallel edges exist between %s and %s. Consider calling "
           + "edgesConnecting() instead.";
   static final String PARALLEL_EDGES_NOT_ALLOWED =
diff --git a/guava/src/com/google/common/graph/Graphs.java b/guava/src/com/google/common/graph/Graphs.java
index 35f0efecf878..6ab9f5661557 100644
--- a/guava/src/com/google/common/graph/Graphs.java
+++ b/guava/src/com/google/common/graph/Graphs.java
@@ -18,6 +18,7 @@
 
 import static com.google.common.base.Preconditions.checkArgument;
 import static com.google.common.graph.GraphConstants.NODE_NOT_IN_GRAPH;
+import static java.util.Objects.requireNonNull;
 
 import com.google.common.annotations.Beta;
 import com.google.common.base.Function;
@@ -33,7 +34,7 @@
 import java.util.Map;
 import java.util.Optional;
 import java.util.Set;
-import org.checkerframework.checker.nullness.qual.Nullable;
+import javax.annotation.CheckForNull;
 
 /**
  * Static utility methods for {@link Graph}, {@link ValueGraph}, and {@link Network} instances.
@@ -43,6 +44,7 @@
  * @since 20.0
  */
 @Beta
+@ElementTypesAreNonnullByDefault
 public final class Graphs {
 
   private Graphs() {}
@@ -99,7 +101,10 @@ public static boolean hasCycle(Network<?, ?> network) {
    * cycle in the graph.
    */
   private static <N> boolean subgraphHasCycle(
-      Graph<N> graph, Map<Object, NodeVisitState> visitedNodes, N node, @Nullable N previousNode) {
+      Graph<N> graph,
+      Map<Object, NodeVisitState> visitedNodes,
+      N node,
+      @CheckForNull N previousNode) {
     NodeVisitState state = visitedNodes.get(node);
     if (state == NodeVisitState.COMPLETE) {
       return false;
@@ -126,7 +131,7 @@ && subgraphHasCycle(graph, visitedNodes, nextNode, node)) {
    * from B to A).
    */
   private static boolean canTraverseWithoutReusingEdge(
-      Graph<?> graph, Object nextNode, @Nullable Object previousNode) {
+      Graph<?> graph, Object nextNode, @CheckForNull Object previousNode) {
     if (graph.isDirected() || !Objects.equal(previousNode, nextNode)) {
       return true;
     }
@@ -263,7 +268,7 @@ private static class TransposedGraph<N> extends ForwardingGraph<N> {
     }
 
     @Override
-    protected Graph<N> delegate() {
+    Graph<N> delegate() {
       return graph;
     }
 
@@ -325,7 +330,7 @@ private static class TransposedValueGraph<N, V> extends ForwardingValueGraph<N,
     }
 
     @Override
-    protected ValueGraph<N, V> delegate() {
+    ValueGraph<N, V> delegate() {
       return graph;
     }
 
@@ -370,12 +375,14 @@ public Optional<V> edgeValue(EndpointPair<N> endpoints) {
     }
 
     @Override
-    public @Nullable V edgeValueOrDefault(N nodeU, N nodeV, @Nullable V defaultValue) {
+    @CheckForNull
+    public V edgeValueOrDefault(N nodeU, N nodeV, @CheckForNull V defaultValue) {
       return delegate().edgeValueOrDefault(nodeV, nodeU, defaultValue); // transpose
     }
 
     @Override
-    public @Nullable V edgeValueOrDefault(EndpointPair<N> endpoints, @Nullable V defaultValue) {
+    @CheckForNull
+    public V edgeValueOrDefault(EndpointPair<N> endpoints, @CheckForNull V defaultValue) {
       return delegate().edgeValueOrDefault(transpose(endpoints), defaultValue);
     }
   }
@@ -388,7 +395,7 @@ private static class TransposedNetwork<N, E> extends ForwardingNetwork<N, E> {
     }
 
     @Override
-    protected Network<N, E> delegate() {
+    Network<N, E> delegate() {
       return network;
     }
 
@@ -449,11 +456,13 @@ public Optional<E> edgeConnecting(EndpointPair<N> endpoints) {
     }
 
     @Override
+    @CheckForNull
     public E edgeConnectingOrNull(N nodeU, N nodeV) {
       return delegate().edgeConnectingOrNull(nodeV, nodeU); // transpose
     }
 
     @Override
+    @CheckForNull
     public E edgeConnectingOrNull(EndpointPair<N> endpoints) {
       return delegate().edgeConnectingOrNull(transpose(endpoints));
     }
@@ -516,8 +525,11 @@ public static <N, V> MutableValueGraph<N, V> inducedSubgraph(
     for (N node : subgraph.nodes()) {
       for (N successorNode : graph.successors(node)) {
         if (subgraph.nodes().contains(successorNode)) {
+          // requireNonNull is safe because the endpoint pair comes from the graph.
           subgraph.putEdgeValue(
-              node, successorNode, graph.edgeValueOrDefault(node, successorNode, null));
+              node,
+              successorNode,
+              requireNonNull(graph.edgeValueOrDefault(node, successorNode, null)));
         }
       }
     }
@@ -572,8 +584,11 @@ public static <N, V> MutableValueGraph<N, V> copyOf(ValueGraph<N, V> graph) {
       copy.addNode(node);
     }
     for (EndpointPair<N> edge : graph.edges()) {
+      // requireNonNull is safe because the endpoint pair comes from the graph.
       copy.putEdgeValue(
-          edge.nodeU(), edge.nodeV(), graph.edgeValueOrDefault(edge.nodeU(), edge.nodeV(), null));
+          edge.nodeU(),
+          edge.nodeV(),
+          requireNonNull(graph.edgeValueOrDefault(edge.nodeU(), edge.nodeV(), null)));
     }
     return copy;
   }
diff --git a/guava/src/com/google/common/graph/ImmutableGraph.java b/guava/src/com/google/common/graph/ImmutableGraph.java
index 4027ca83de29..f829e9699993 100644
--- a/guava/src/com/google/common/graph/ImmutableGraph.java
+++ b/guava/src/com/google/common/graph/ImmutableGraph.java
@@ -45,6 +45,7 @@
  */
 @Beta
 @Immutable(containerOf = {"N"})
+@ElementTypesAreNonnullByDefault
 public class ImmutableGraph<N> extends ForwardingGraph<N> {
   @SuppressWarnings("Immutable") // The backing graph must be immutable.
   private final BaseGraph<N> backingGraph;
@@ -86,7 +87,7 @@ private static <N> ImmutableMap<N, GraphConnections<N, Presence>> getNodeConnect
     for (N node : graph.nodes()) {
       nodeConnections.put(node, connectionsOf(graph, node));
     }
-    return nodeConnections.build();
+    return nodeConnections.buildOrThrow();
   }
 
   @SuppressWarnings("unchecked")
@@ -100,7 +101,7 @@ private static <N> GraphConnections<N, Presence> connectionsOf(Graph<N> graph, N
   }
 
   @Override
-  protected BaseGraph<N> delegate() {
+  BaseGraph<N> delegate() {
     return backingGraph;
   }
 
diff --git a/guava/src/com/google/common/graph/ImmutableNetwork.java b/guava/src/com/google/common/graph/ImmutableNetwork.java
index b35d7220817d..c29f8a392813 100644
--- a/guava/src/com/google/common/graph/ImmutableNetwork.java
+++ b/guava/src/com/google/common/graph/ImmutableNetwork.java
@@ -46,6 +46,7 @@
 @Beta
 @Immutable(containerOf = {"N", "E"})
 @SuppressWarnings("Immutable") // Extends StandardNetwork but uses ImmutableMaps.
+@ElementTypesAreNonnullByDefault
 public final class ImmutableNetwork<N, E> extends StandardNetwork<N, E> {
 
   private ImmutableNetwork(Network<N, E> network) {
@@ -72,7 +73,7 @@ public static <N, E> ImmutableNetwork<N, E> copyOf(ImmutableNetwork<N, E> networ
 
   @Override
   public ImmutableGraph<N> asGraph() {
-    return new ImmutableGraph<N>(super.asGraph()); // safe because the view is effectively immutable
+    return new ImmutableGraph<>(super.asGraph()); // safe because the view is effectively immutable
   }
 
   private static <N, E> Map<N, NetworkConnections<N, E>> getNodeConnections(Network<N, E> network) {
@@ -83,7 +84,7 @@ private static <N, E> Map<N, NetworkConnections<N, E>> getNodeConnections(Networ
     for (N node : network.nodes()) {
       nodeConnections.put(node, connectionsOf(network, node));
     }
-    return nodeConnections.build();
+    return nodeConnections.buildOrThrow();
   }
 
   private static <N, E> Map<E, N> getEdgeToReferenceNode(Network<N, E> network) {
@@ -94,7 +95,7 @@ private static <N, E> Map<E, N> getEdgeToReferenceNode(Network<N, E> network) {
     for (E edge : network.edges()) {
       edgeToReferenceNode.put(edge, network.incidentNodes(edge).nodeU());
     }
-    return edgeToReferenceNode.build();
+    return edgeToReferenceNode.buildOrThrow();
   }
 
   private static <N, E> NetworkConnections<N, E> connectionsOf(Network<N, E> network, N node) {
@@ -114,31 +115,16 @@ private static <N, E> NetworkConnections<N, E> connectionsOf(Network<N, E> netwo
     }
   }
 
-  private static <N, E> Function<E, N> sourceNodeFn(final Network<N, E> network) {
-    return new Function<E, N>() {
-      @Override
-      public N apply(E edge) {
-        return network.incidentNodes(edge).source();
-      }
-    };
+  private static <N, E> Function<E, N> sourceNodeFn(Network<N, E> network) {
+    return (E edge) -> network.incidentNodes(edge).source();
   }
 
-  private static <N, E> Function<E, N> targetNodeFn(final Network<N, E> network) {
-    return new Function<E, N>() {
-      @Override
-      public N apply(E edge) {
-        return network.incidentNodes(edge).target();
-      }
-    };
+  private static <N, E> Function<E, N> targetNodeFn(Network<N, E> network) {
+    return (E edge) -> network.incidentNodes(edge).target();
   }
 
-  private static <N, E> Function<E, N> adjacentNodeFn(final Network<N, E> network, final N node) {
-    return new Function<E, N>() {
-      @Override
-      public N apply(E edge) {
-        return network.incidentNodes(edge).adjacentNode(node);
-      }
-    };
+  private static <N, E> Function<E, N> adjacentNodeFn(Network<N, E> network, N node) {
+    return (E edge) -> network.incidentNodes(edge).adjacentNode(node);
   }
 
   /**
diff --git a/guava/src/com/google/common/graph/ImmutableValueGraph.java b/guava/src/com/google/common/graph/ImmutableValueGraph.java
index f2e2386340eb..eb17067fca43 100644
--- a/guava/src/com/google/common/graph/ImmutableValueGraph.java
+++ b/guava/src/com/google/common/graph/ImmutableValueGraph.java
@@ -17,6 +17,7 @@
 package com.google.common.graph;
 
 import static com.google.common.base.Preconditions.checkNotNull;
+import static java.util.Objects.requireNonNull;
 
 import com.google.common.annotations.Beta;
 import com.google.common.base.Function;
@@ -43,6 +44,7 @@
 @Beta
 @Immutable(containerOf = {"N", "V"})
 @SuppressWarnings("Immutable") // Extends StandardValueGraph but uses ImmutableMaps.
+@ElementTypesAreNonnullByDefault
 public final class ImmutableValueGraph<N, V> extends StandardValueGraph<N, V> {
 
   private ImmutableValueGraph(ValueGraph<N, V> graph) {
@@ -73,7 +75,7 @@ public ElementOrder<N> incidentEdgeOrder() {
 
   @Override
   public ImmutableGraph<N> asGraph() {
-    return new ImmutableGraph<N>(this); // safe because the view is effectively immutable
+    return new ImmutableGraph<>(this); // safe because the view is effectively immutable
   }
 
   private static <N, V> ImmutableMap<N, GraphConnections<N, V>> getNodeConnections(
@@ -85,18 +87,14 @@ private static <N, V> ImmutableMap<N, GraphConnections<N, V>> getNodeConnections
     for (N node : graph.nodes()) {
       nodeConnections.put(node, connectionsOf(graph, node));
     }
-    return nodeConnections.build();
+    return nodeConnections.buildOrThrow();
   }
 
-  private static <N, V> GraphConnections<N, V> connectionsOf(
-      final ValueGraph<N, V> graph, final N node) {
+  private static <N, V> GraphConnections<N, V> connectionsOf(ValueGraph<N, V> graph, N node) {
     Function<N, V> successorNodeToValueFn =
-        new Function<N, V>() {
-          @Override
-          public V apply(N successorNode) {
-            return graph.edgeValueOrDefault(node, successorNode, null);
-          }
-        };
+        (N successorNode) ->
+            // requireNonNull is safe because the endpoint pair comes from the graph.
+            requireNonNull(graph.edgeValueOrDefault(node, successorNode, null));
     return graph.isDirected()
         ? DirectedGraphConnections.ofImmutable(
             node, graph.incidentEdges(node), successorNodeToValueFn)
diff --git a/guava/src/com/google/common/graph/IncidentEdgeSet.java b/guava/src/com/google/common/graph/IncidentEdgeSet.java
index f306a677ac66..ac94b65779d4 100644
--- a/guava/src/com/google/common/graph/IncidentEdgeSet.java
+++ b/guava/src/com/google/common/graph/IncidentEdgeSet.java
@@ -18,15 +18,16 @@
 
 import java.util.AbstractSet;
 import java.util.Set;
-import org.checkerframework.checker.nullness.qual.Nullable;
+import javax.annotation.CheckForNull;
 
 /**
  * Abstract base class for an incident edges set that allows different implementations of {@link
  * AbstractSet#iterator()}.
  */
+@ElementTypesAreNonnullByDefault
 abstract class IncidentEdgeSet<N> extends AbstractSet<EndpointPair<N>> {
-  protected final N node;
-  protected final BaseGraph<N> graph;
+  final N node;
+  final BaseGraph<N> graph;
 
   IncidentEdgeSet(BaseGraph<N> graph, N node) {
     this.graph = graph;
@@ -34,7 +35,7 @@ abstract class IncidentEdgeSet<N> extends AbstractSet<EndpointPair<N>> {
   }
 
   @Override
-  public boolean remove(Object o) {
+  public boolean remove(@CheckForNull Object o) {
     throw new UnsupportedOperationException();
   }
 
@@ -50,7 +51,7 @@ public int size() {
   }
 
   @Override
-  public boolean contains(@Nullable Object obj) {
+  public boolean contains(@CheckForNull Object obj) {
     if (!(obj instanceof EndpointPair)) {
       return false;
     }
diff --git a/guava/src/com/google/common/graph/MapIteratorCache.java b/guava/src/com/google/common/graph/MapIteratorCache.java
index 182a67fe585f..05cdde8c3f12 100644
--- a/guava/src/com/google/common/graph/MapIteratorCache.java
+++ b/guava/src/com/google/common/graph/MapIteratorCache.java
@@ -25,7 +25,7 @@
 import java.util.Map;
 import java.util.Map.Entry;
 import java.util.Set;
-import org.checkerframework.checker.nullness.qual.Nullable;
+import javax.annotation.CheckForNull;
 
 /**
  * A map-like data structure that wraps a backing map and caches values while iterating through
@@ -41,6 +41,7 @@
  *
  * @author James Sexton
  */
+@ElementTypesAreNonnullByDefault
 class MapIteratorCache<K, V> {
   private final Map<K, V> backingMap;
 
@@ -53,47 +54,61 @@ class MapIteratorCache<K, V> {
    * while writing to it in another. All it does is help with _reading_ from multiple threads
    * concurrently. For more information, see AbstractNetworkTest.concurrentIteration.
    */
-  private transient volatile @Nullable Entry<K, V> cacheEntry;
+  @CheckForNull private transient volatile Entry<K, V> cacheEntry;
 
   MapIteratorCache(Map<K, V> backingMap) {
     this.backingMap = checkNotNull(backingMap);
   }
 
   @CanIgnoreReturnValue
-  public final V put(@Nullable K key, @Nullable V value) {
+  @CheckForNull
+  final V put(K key, V value) {
+    checkNotNull(key);
+    checkNotNull(value);
     clearCache();
     return backingMap.put(key, value);
   }
 
   @CanIgnoreReturnValue
-  public final V remove(@Nullable Object key) {
+  @CheckForNull
+  final V remove(Object key) {
+    checkNotNull(key);
     clearCache();
     return backingMap.remove(key);
   }
 
-  public final void clear() {
+  final void clear() {
     clearCache();
     backingMap.clear();
   }
 
-  public V get(@Nullable Object key) {
+  @CheckForNull
+  V get(Object key) {
+    checkNotNull(key);
     V value = getIfCached(key);
-    return (value != null) ? value : getWithoutCaching(key);
+    // TODO(b/192579700): Use a ternary once it no longer confuses our nullness checker.
+    if (value == null) {
+      return getWithoutCaching(key);
+    } else {
+      return value;
+    }
   }
 
-  public final V getWithoutCaching(@Nullable Object key) {
+  @CheckForNull
+  final V getWithoutCaching(Object key) {
+    checkNotNull(key);
     return backingMap.get(key);
   }
 
-  public final boolean containsKey(@Nullable Object key) {
+  final boolean containsKey(@CheckForNull Object key) {
     return getIfCached(key) != null || backingMap.containsKey(key);
   }
 
-  public final Set<K> unmodifiableKeySet() {
+  final Set<K> unmodifiableKeySet() {
     return new AbstractSet<K>() {
       @Override
       public UnmodifiableIterator<K> iterator() {
-        final Iterator<Entry<K, V>> entryIterator = backingMap.entrySet().iterator();
+        Iterator<Entry<K, V>> entryIterator = backingMap.entrySet().iterator();
 
         return new UnmodifiableIterator<K>() {
           @Override
@@ -116,15 +131,16 @@ public int size() {
       }
 
       @Override
-      public boolean contains(@Nullable Object key) {
+      public boolean contains(@CheckForNull Object key) {
         return containsKey(key);
       }
     };
   }
 
-  // Internal methods ('protected' is still package-visible, but treat as only subclass-visible)
+  // Internal methods (package-visible, but treat as only subclass-visible)
 
-  protected V getIfCached(@Nullable Object key) {
+  @CheckForNull
+  V getIfCached(@CheckForNull Object key) {
     Entry<K, V> entry = cacheEntry; // store local reference for thread-safety
 
     // Check cache. We use == on purpose because it's cheaper and a cache miss is ok.
@@ -134,7 +150,7 @@ protected V getIfCached(@Nullable Object key) {
     return null;
   }
 
-  protected void clearCache() {
+  void clearCache() {
     cacheEntry = null;
   }
 }
diff --git a/guava/src/com/google/common/graph/MapRetrievalCache.java b/guava/src/com/google/common/graph/MapRetrievalCache.java
index 3a406e94d690..ada78f28414d 100644
--- a/guava/src/com/google/common/graph/MapRetrievalCache.java
+++ b/guava/src/com/google/common/graph/MapRetrievalCache.java
@@ -16,8 +16,10 @@
 
 package com.google.common.graph;
 
+import static com.google.common.base.Preconditions.checkNotNull;
+
 import java.util.Map;
-import org.checkerframework.checker.nullness.qual.Nullable;
+import javax.annotation.CheckForNull;
 
 /**
  * A {@link MapIteratorCache} that adds additional caching. In addition to the caching provided by
@@ -25,10 +27,11 @@
  *
  * @author James Sexton
  */
-class MapRetrievalCache<K, V> extends MapIteratorCache<K, V> {
+@ElementTypesAreNonnullByDefault
+final class MapRetrievalCache<K, V> extends MapIteratorCache<K, V> {
   // See the note about volatile in the superclass.
-  private transient volatile @Nullable CacheEntry<K, V> cacheEntry1;
-  private transient volatile @Nullable CacheEntry<K, V> cacheEntry2;
+  @CheckForNull private transient volatile CacheEntry<K, V> cacheEntry1;
+  @CheckForNull private transient volatile CacheEntry<K, V> cacheEntry2;
 
   MapRetrievalCache(Map<K, V> backingMap) {
     super(backingMap);
@@ -36,7 +39,9 @@ class MapRetrievalCache<K, V> extends MapIteratorCache<K, V> {
 
   @SuppressWarnings("unchecked") // Safe because we only cast if key is found in map.
   @Override
-  public V get(@Nullable Object key) {
+  @CheckForNull
+  V get(Object key) {
+    checkNotNull(key);
     V value = getIfCached(key);
     if (value != null) {
       return value;
@@ -49,10 +54,11 @@ public V get(@Nullable Object key) {
     return value;
   }
 
-  // Internal methods ('protected' is still package-visible, but treat as only subclass-visible)
+  // Internal methods (package-visible, but treat as only subclass-visible)
 
   @Override
-  protected V getIfCached(@Nullable Object key) {
+  @CheckForNull
+  V getIfCached(@CheckForNull Object key) {
     V value = super.getIfCached(key);
     if (value != null) {
       return value;
@@ -78,7 +84,7 @@ protected V getIfCached(@Nullable Object key) {
   }
 
   @Override
-  protected void clearCache() {
+  void clearCache() {
     super.clearCache();
     cacheEntry1 = null;
     cacheEntry2 = null;
diff --git a/guava/src/com/google/common/graph/MultiEdgesConnecting.java b/guava/src/com/google/common/graph/MultiEdgesConnecting.java
index 5bddfbbdf202..620f986a555a 100644
--- a/guava/src/com/google/common/graph/MultiEdgesConnecting.java
+++ b/guava/src/com/google/common/graph/MultiEdgesConnecting.java
@@ -24,7 +24,7 @@
 import java.util.Iterator;
 import java.util.Map;
 import java.util.Map.Entry;
-import org.checkerframework.checker.nullness.qual.Nullable;
+import javax.annotation.CheckForNull;
 
 /**
  * A class to represent the set of edges connecting an (implicit) origin node to a target node.
@@ -35,6 +35,7 @@
  * @author James Sexton
  * @param <E> Edge parameter type
  */
+@ElementTypesAreNonnullByDefault
 abstract class MultiEdgesConnecting<E> extends AbstractSet<E> {
 
   private final Map<E, ?> outEdgeToNode;
@@ -47,9 +48,10 @@ abstract class MultiEdgesConnecting<E> extends AbstractSet<E> {
 
   @Override
   public UnmodifiableIterator<E> iterator() {
-    final Iterator<? extends Entry<E, ?>> entries = outEdgeToNode.entrySet().iterator();
+    Iterator<? extends Entry<E, ?>> entries = outEdgeToNode.entrySet().iterator();
     return new AbstractIterator<E>() {
       @Override
+      @CheckForNull
       protected E computeNext() {
         while (entries.hasNext()) {
           Entry<E, ?> entry = entries.next();
@@ -63,7 +65,7 @@ protected E computeNext() {
   }
 
   @Override
-  public boolean contains(@Nullable Object edge) {
+  public boolean contains(@CheckForNull Object edge) {
     return targetNode.equals(outEdgeToNode.get(edge));
   }
 }
diff --git a/guava/src/com/google/common/graph/MutableGraph.java b/guava/src/com/google/common/graph/MutableGraph.java
index 8324079f6c08..b1f3359cab58 100644
--- a/guava/src/com/google/common/graph/MutableGraph.java
+++ b/guava/src/com/google/common/graph/MutableGraph.java
@@ -29,6 +29,7 @@
  * @since 20.0
  */
 @Beta
+@ElementTypesAreNonnullByDefault
 public interface MutableGraph<N> extends Graph<N> {
 
   /**
diff --git a/guava/src/com/google/common/graph/MutableNetwork.java b/guava/src/com/google/common/graph/MutableNetwork.java
index d702903604cf..64acb13162af 100644
--- a/guava/src/com/google/common/graph/MutableNetwork.java
+++ b/guava/src/com/google/common/graph/MutableNetwork.java
@@ -30,6 +30,7 @@
  * @since 20.0
  */
 @Beta
+@ElementTypesAreNonnullByDefault
 public interface MutableNetwork<N, E> extends Network<N, E> {
 
   /**
diff --git a/guava/src/com/google/common/graph/MutableValueGraph.java b/guava/src/com/google/common/graph/MutableValueGraph.java
index 70b286dee185..f32d2ee7a38c 100644
--- a/guava/src/com/google/common/graph/MutableValueGraph.java
+++ b/guava/src/com/google/common/graph/MutableValueGraph.java
@@ -18,6 +18,7 @@
 
 import com.google.common.annotations.Beta;
 import com.google.errorprone.annotations.CanIgnoreReturnValue;
+import javax.annotation.CheckForNull;
 
 /**
  * A subinterface of {@link ValueGraph} which adds mutation methods. When mutation is not required,
@@ -29,6 +30,7 @@
  * @since 20.0
  */
 @Beta
+@ElementTypesAreNonnullByDefault
 public interface MutableValueGraph<N, V> extends ValueGraph<N, V> {
 
   /**
@@ -59,6 +61,7 @@ public interface MutableValueGraph<N, V> extends ValueGraph<N, V> {
    *     #allowsSelfLoops()}
    */
   @CanIgnoreReturnValue
+  @CheckForNull
   V putEdgeValue(N nodeU, N nodeV, V value);
 
   /**
@@ -83,6 +86,7 @@ public interface MutableValueGraph<N, V> extends ValueGraph<N, V> {
    * @since 27.1
    */
   @CanIgnoreReturnValue
+  @CheckForNull
   V putEdgeValue(EndpointPair<N> endpoints, V value);
 
   /**
@@ -100,6 +104,7 @@ public interface MutableValueGraph<N, V> extends ValueGraph<N, V> {
    *     nodeV}, or null if there was no such edge.
    */
   @CanIgnoreReturnValue
+  @CheckForNull
   V removeEdge(N nodeU, N nodeV);
 
   /**
@@ -112,5 +117,6 @@ public interface MutableValueGraph<N, V> extends ValueGraph<N, V> {
    * @since 27.1
    */
   @CanIgnoreReturnValue
+  @CheckForNull
   V removeEdge(EndpointPair<N> endpoints);
 }
diff --git a/guava/src/com/google/common/graph/Network.java b/guava/src/com/google/common/graph/Network.java
index 6bb845228001..c700d3378de6 100644
--- a/guava/src/com/google/common/graph/Network.java
+++ b/guava/src/com/google/common/graph/Network.java
@@ -20,7 +20,7 @@
 import com.google.errorprone.annotations.DoNotMock;
 import java.util.Optional;
 import java.util.Set;
-import org.checkerframework.checker.nullness.qual.Nullable;
+import javax.annotation.CheckForNull;
 
 /**
  * An interface for <a
@@ -104,6 +104,7 @@
  */
 @Beta
 @DoNotMock("Use NetworkBuilder to create a real instance")
+@ElementTypesAreNonnullByDefault
 public interface Network<N, E> extends SuccessorsFunction<N>, PredecessorsFunction<N> {
   //
   // Network-level accessors
@@ -348,7 +349,7 @@ public interface Network<N, E> extends SuccessorsFunction<N>, PredecessorsFuncti
    *     network
    * @since 23.0
    */
-  @Nullable
+  @CheckForNull
   E edgeConnectingOrNull(N nodeU, N nodeV);
 
   /**
@@ -363,7 +364,7 @@ public interface Network<N, E> extends SuccessorsFunction<N>, PredecessorsFuncti
    * @throws IllegalArgumentException if the endpoints are unordered and the graph is directed
    * @since 27.1
    */
-  @Nullable
+  @CheckForNull
   E edgeConnectingOrNull(EndpointPair<N> endpoints);
 
   /**
@@ -415,7 +416,7 @@ public interface Network<N, E> extends SuccessorsFunction<N>, PredecessorsFuncti
    * <p>A reference implementation of this is provided by {@link AbstractNetwork#equals(Object)}.
    */
   @Override
-  boolean equals(@Nullable Object object);
+  boolean equals(@CheckForNull Object object);
 
   /**
    * Returns the hash code for this network. The hash code of a network is defined as the hash code
diff --git a/guava/src/com/google/common/graph/NetworkBuilder.java b/guava/src/com/google/common/graph/NetworkBuilder.java
index d289ee2d53d6..968944493c7b 100644
--- a/guava/src/com/google/common/graph/NetworkBuilder.java
+++ b/guava/src/com/google/common/graph/NetworkBuilder.java
@@ -67,6 +67,7 @@
  * @since 20.0
  */
 @Beta
+@ElementTypesAreNonnullByDefault
 public final class NetworkBuilder<N, E> extends AbstractGraphBuilder<N> {
   boolean allowsParallelEdges = false;
   ElementOrder<? super E> edgeOrder = ElementOrder.insertion();
diff --git a/guava/src/com/google/common/graph/NetworkConnections.java b/guava/src/com/google/common/graph/NetworkConnections.java
index 16a68d6cb830..94d1780d3135 100644
--- a/guava/src/com/google/common/graph/NetworkConnections.java
+++ b/guava/src/com/google/common/graph/NetworkConnections.java
@@ -18,6 +18,7 @@
 
 import com.google.errorprone.annotations.CanIgnoreReturnValue;
 import java.util.Set;
+import javax.annotation.CheckForNull;
 
 /**
  * An interface for representing and manipulating an origin node's adjacent nodes and incident edges
@@ -27,6 +28,7 @@
  * @param <N> Node parameter type
  * @param <E> Edge parameter type
  */
+@ElementTypesAreNonnullByDefault
 interface NetworkConnections<N, E> {
 
   Set<N> adjacentNodes();
@@ -60,6 +62,7 @@ interface NetworkConnections<N, E> {
    * <p>In the undirected case, returns {@code null} if {@code isSelfLoop} is true.
    */
   @CanIgnoreReturnValue
+  @CheckForNull
   N removeInEdge(E edge, boolean isSelfLoop);
 
   /** Remove {@code edge} from the set of outgoing edges. Returns the former successor node. */
diff --git a/guava/src/com/google/common/graph/ParametricNullness.java b/guava/src/com/google/common/graph/ParametricNullness.java
new file mode 100644
index 000000000000..87ff930a4aac
--- /dev/null
+++ b/guava/src/com/google/common/graph/ParametricNullness.java
@@ -0,0 +1,52 @@
+/*
+ * Copyright (C) 2021 The Guava Authors
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package com.google.common.graph;
+
+import static java.lang.annotation.ElementType.FIELD;
+import static java.lang.annotation.ElementType.METHOD;
+import static java.lang.annotation.ElementType.PARAMETER;
+import static java.lang.annotation.RetentionPolicy.RUNTIME;
+
+import com.google.common.annotations.GwtCompatible;
+import java.lang.annotation.Retention;
+import java.lang.annotation.Target;
+
+/**
+ * Marks a "top-level" type-variable usage as the closest we can get to "non-nullable when
+ * non-nullable; nullable when nullable" (like the Android <a
+ * href="https://android.googlesource.com/platform/libcore/+/master/luni/src/main/java/libcore/util/NullFromTypeParam.java">{@code
+ * NullFromTypeParam}</a>).
+ *
+ * <p>Consumers of this annotation include:
+ *
+ * <ul>
+ *   <li>Kotlin, for which it makes the type-variable usage (a) a Kotlin platform type when the type
+ *       argument is non-nullable and (b) nullable when the type argument is nullable. We use this
+ *       to "undo" {@link ElementTypesAreNonnullByDefault}.
+ *   <li><a href="https://developers.google.com/j2objc">J2ObjC</a>
+ *   <li>{@code NullPointerTester}, at least in the Android backport (where the type-use annotations
+ *       {@code NullPointerTester} would need are not available) and in case of <a
+ *       href="https://bugs.openjdk.java.net/browse/JDK-8202469">JDK-8202469</a>
+ * </ul>
+ *
+ */
+@GwtCompatible
+@Retention(RUNTIME)
+@Target({FIELD, METHOD, PARAMETER})
+@javax.annotation.meta.TypeQualifierNickname
+@javax.annotation.Nonnull(when = javax.annotation.meta.When.UNKNOWN)
+@interface ParametricNullness {}
diff --git a/guava/src/com/google/common/graph/PredecessorsFunction.java b/guava/src/com/google/common/graph/PredecessorsFunction.java
index f9ca48ae77b9..750a8acd603b 100644
--- a/guava/src/com/google/common/graph/PredecessorsFunction.java
+++ b/guava/src/com/google/common/graph/PredecessorsFunction.java
@@ -80,6 +80,7 @@
  */
 @Beta
 @DoNotMock("Implement with a lambda, or use GraphBuilder to build a Graph with the desired edges")
+@ElementTypesAreNonnullByDefault
 public interface PredecessorsFunction<N> {
 
   /**
diff --git a/guava/src/com/google/common/graph/StandardMutableGraph.java b/guava/src/com/google/common/graph/StandardMutableGraph.java
index 41acccff5963..1be9640f419e 100644
--- a/guava/src/com/google/common/graph/StandardMutableGraph.java
+++ b/guava/src/com/google/common/graph/StandardMutableGraph.java
@@ -28,6 +28,7 @@
  * @author James Sexton
  * @param <N> Node parameter type
  */
+@ElementTypesAreNonnullByDefault
 final class StandardMutableGraph<N> extends ForwardingGraph<N> implements MutableGraph<N> {
   private final MutableValueGraph<N, Presence> backingValueGraph;
 
@@ -37,7 +38,7 @@ final class StandardMutableGraph<N> extends ForwardingGraph<N> implements Mutabl
   }
 
   @Override
-  protected BaseGraph<N> delegate() {
+  BaseGraph<N> delegate() {
     return backingValueGraph;
   }
 
diff --git a/guava/src/com/google/common/graph/StandardMutableNetwork.java b/guava/src/com/google/common/graph/StandardMutableNetwork.java
index 8cfe9c526021..c58b6d39093e 100644
--- a/guava/src/com/google/common/graph/StandardMutableNetwork.java
+++ b/guava/src/com/google/common/graph/StandardMutableNetwork.java
@@ -22,6 +22,7 @@
 import static com.google.common.graph.GraphConstants.PARALLEL_EDGES_NOT_ALLOWED;
 import static com.google.common.graph.GraphConstants.REUSING_EDGE;
 import static com.google.common.graph.GraphConstants.SELF_LOOPS_NOT_ALLOWED;
+import static java.util.Objects.requireNonNull;
 
 import com.google.common.collect.ImmutableList;
 import com.google.errorprone.annotations.CanIgnoreReturnValue;
@@ -39,6 +40,7 @@
  * @param <N> Node parameter type
  * @param <E> Edge parameter type
  */
+@ElementTypesAreNonnullByDefault
 final class StandardMutableNetwork<N, E> extends StandardNetwork<N, E>
     implements MutableNetwork<N, E> {
 
@@ -152,9 +154,10 @@ public boolean removeEdge(E edge) {
       return false;
     }
 
-    NetworkConnections<N, E> connectionsU = nodeConnections.get(nodeU);
+    // requireNonNull is safe because of the edgeToReferenceNode check above.
+    NetworkConnections<N, E> connectionsU = requireNonNull(nodeConnections.get(nodeU));
     N nodeV = connectionsU.adjacentNode(edge);
-    NetworkConnections<N, E> connectionsV = nodeConnections.get(nodeV);
+    NetworkConnections<N, E> connectionsV = requireNonNull(nodeConnections.get(nodeV));
     connectionsU.removeOutEdge(edge);
     connectionsV.removeInEdge(edge, allowsSelfLoops() && nodeU.equals(nodeV));
     edgeToReferenceNode.remove(edge);
diff --git a/guava/src/com/google/common/graph/StandardMutableValueGraph.java b/guava/src/com/google/common/graph/StandardMutableValueGraph.java
index 558d8d60976e..0ea641a5b1cd 100644
--- a/guava/src/com/google/common/graph/StandardMutableValueGraph.java
+++ b/guava/src/com/google/common/graph/StandardMutableValueGraph.java
@@ -22,8 +22,10 @@
 import static com.google.common.graph.GraphConstants.SELF_LOOPS_NOT_ALLOWED;
 import static com.google.common.graph.Graphs.checkNonNegative;
 import static com.google.common.graph.Graphs.checkPositive;
+import static java.util.Objects.requireNonNull;
 
 import com.google.errorprone.annotations.CanIgnoreReturnValue;
+import javax.annotation.CheckForNull;
 
 /**
  * Standard implementation of {@link MutableValueGraph} that supports both directed and undirected
@@ -38,6 +40,7 @@
  * @param <N> Node parameter type
  * @param <V> Value parameter type
  */
+@ElementTypesAreNonnullByDefault
 final class StandardMutableValueGraph<N, V> extends StandardValueGraph<N, V>
     implements MutableValueGraph<N, V> {
 
@@ -81,6 +84,7 @@ private GraphConnections<N, V> addNodeInternal(N node) {
 
   @Override
   @CanIgnoreReturnValue
+  @CheckForNull
   public V putEdgeValue(N nodeU, N nodeV, V value) {
     checkNotNull(nodeU, "nodeU");
     checkNotNull(nodeV, "nodeV");
@@ -108,6 +112,7 @@ public V putEdgeValue(N nodeU, N nodeV, V value) {
 
   @Override
   @CanIgnoreReturnValue
+  @CheckForNull
   public V putEdgeValue(EndpointPair<N> endpoints, V value) {
     validateEndpoints(endpoints);
     return putEdgeValue(endpoints.nodeU(), endpoints.nodeV(), value);
@@ -132,12 +137,16 @@ public boolean removeNode(N node) {
     }
 
     for (N successor : connections.successors()) {
-      nodeConnections.getWithoutCaching(successor).removePredecessor(node);
+      // requireNonNull is safe because the node is a successor.
+      requireNonNull(nodeConnections.getWithoutCaching(successor)).removePredecessor(node);
       --edgeCount;
     }
     if (isDirected()) { // In undirected graphs, the successor and predecessor sets are equal.
       for (N predecessor : connections.predecessors()) {
-        checkState(nodeConnections.getWithoutCaching(predecessor).removeSuccessor(node) != null);
+        // requireNonNull is safe because the node is a predecessor.
+        checkState(
+            requireNonNull(nodeConnections.getWithoutCaching(predecessor)).removeSuccessor(node)
+                != null);
         --edgeCount;
       }
     }
@@ -148,6 +157,7 @@ public boolean removeNode(N node) {
 
   @Override
   @CanIgnoreReturnValue
+  @CheckForNull
   public V removeEdge(N nodeU, N nodeV) {
     checkNotNull(nodeU, "nodeU");
     checkNotNull(nodeV, "nodeV");
@@ -168,6 +178,7 @@ public V removeEdge(N nodeU, N nodeV) {
 
   @Override
   @CanIgnoreReturnValue
+  @CheckForNull
   public V removeEdge(EndpointPair<N> endpoints) {
     validateEndpoints(endpoints);
     return removeEdge(endpoints.nodeU(), endpoints.nodeV());
diff --git a/guava/src/com/google/common/graph/StandardNetwork.java b/guava/src/com/google/common/graph/StandardNetwork.java
index 1b82301f91f8..2aa103f99683 100644
--- a/guava/src/com/google/common/graph/StandardNetwork.java
+++ b/guava/src/com/google/common/graph/StandardNetwork.java
@@ -22,12 +22,12 @@
 import static com.google.common.graph.GraphConstants.DEFAULT_NODE_COUNT;
 import static com.google.common.graph.GraphConstants.EDGE_NOT_IN_GRAPH;
 import static com.google.common.graph.GraphConstants.NODE_NOT_IN_GRAPH;
+import static java.util.Objects.requireNonNull;
 
 import com.google.common.collect.ImmutableSet;
 import java.util.Map;
 import java.util.Set;
 import java.util.TreeMap;
-import org.checkerframework.checker.nullness.qual.Nullable;
 
 /**
  * Standard implementation of {@link Network} that supports the options supplied by {@link
@@ -48,6 +48,7 @@
  * @param <N> Node parameter type
  * @param <E> Edge parameter type
  */
+@ElementTypesAreNonnullByDefault
 class StandardNetwork<N, E> extends AbstractNetwork<N, E> {
   private final boolean isDirected;
   private final boolean allowsParallelEdges;
@@ -55,11 +56,11 @@ class StandardNetwork<N, E> extends AbstractNetwork<N, E> {
   private final ElementOrder<N> nodeOrder;
   private final ElementOrder<E> edgeOrder;
 
-  protected final MapIteratorCache<N, NetworkConnections<N, E>> nodeConnections;
+  final MapIteratorCache<N, NetworkConnections<N, E>> nodeConnections;
 
   // We could make this a Map<E, EndpointPair<N>>. It would make incidentNodes(edge) slightly
   // faster, but also make Networks consume 5 to 20+% (increasing with average degree) more memory.
-  protected final MapIteratorCache<E, N> edgeToReferenceNode; // referenceNode == source if directed
+  final MapIteratorCache<E, N> edgeToReferenceNode; // referenceNode == source if directed
 
   /** Constructs a graph with the properties specified in {@code builder}. */
   StandardNetwork(NetworkBuilder<? super N, ? super E> builder) {
@@ -135,7 +136,8 @@ public Set<E> incidentEdges(N node) {
   @Override
   public EndpointPair<N> incidentNodes(E edge) {
     N nodeU = checkedReferenceNode(edge);
-    N nodeV = nodeConnections.get(nodeU).adjacentNode(edge);
+    // requireNonNull is safe because checkedReferenceNode made sure the edge is in the network.
+    N nodeV = requireNonNull(nodeConnections.get(nodeU)).adjacentNode(edge);
     return EndpointPair.of(this, nodeU, nodeV);
   }
 
@@ -174,7 +176,7 @@ public Set<N> successors(N node) {
     return checkedConnections(node).successors();
   }
 
-  protected final NetworkConnections<N, E> checkedConnections(N node) {
+  final NetworkConnections<N, E> checkedConnections(N node) {
     NetworkConnections<N, E> connections = nodeConnections.get(node);
     if (connections == null) {
       checkNotNull(node);
@@ -183,7 +185,7 @@ protected final NetworkConnections<N, E> checkedConnections(N node) {
     return connections;
   }
 
-  protected final N checkedReferenceNode(E edge) {
+  final N checkedReferenceNode(E edge) {
     N referenceNode = edgeToReferenceNode.get(edge);
     if (referenceNode == null) {
       checkNotNull(edge);
@@ -192,11 +194,11 @@ protected final N checkedReferenceNode(E edge) {
     return referenceNode;
   }
 
-  protected final boolean containsNode(@Nullable N node) {
+  final boolean containsNode(N node) {
     return nodeConnections.containsKey(node);
   }
 
-  protected final boolean containsEdge(@Nullable E edge) {
+  final boolean containsEdge(E edge) {
     return edgeToReferenceNode.containsKey(edge);
   }
 }
diff --git a/guava/src/com/google/common/graph/StandardValueGraph.java b/guava/src/com/google/common/graph/StandardValueGraph.java
index 8da0b0ff19b9..ab3ae582b55e 100644
--- a/guava/src/com/google/common/graph/StandardValueGraph.java
+++ b/guava/src/com/google/common/graph/StandardValueGraph.java
@@ -24,7 +24,7 @@
 import java.util.Map;
 import java.util.Set;
 import java.util.TreeMap;
-import org.checkerframework.checker.nullness.qual.Nullable;
+import javax.annotation.CheckForNull;
 
 /**
  * Standard implementation of {@link ValueGraph} that supports the options supplied by {@link
@@ -43,14 +43,15 @@
  * @param <N> Node parameter type
  * @param <V> Value parameter type
  */
+@ElementTypesAreNonnullByDefault
 class StandardValueGraph<N, V> extends AbstractValueGraph<N, V> {
   private final boolean isDirected;
   private final boolean allowsSelfLoops;
   private final ElementOrder<N> nodeOrder;
 
-  protected final MapIteratorCache<N, GraphConnections<N, V>> nodeConnections;
+  final MapIteratorCache<N, GraphConnections<N, V>> nodeConnections;
 
-  protected long edgeCount; // must be updated when edges are added or removed
+  long edgeCount; // must be updated when edges are added or removed
 
   /** Constructs a graph with the properties specified in {@code builder}. */
   StandardValueGraph(AbstractGraphBuilder<? super N> builder) {
@@ -117,7 +118,7 @@ public Set<N> successors(N node) {
 
   @Override
   public Set<EndpointPair<N>> incidentEdges(N node) {
-    final GraphConnections<N, V> connections = checkedConnections(node);
+    GraphConnections<N, V> connections = checkedConnections(node);
 
     return new IncidentEdgeSet<N>(this, node) {
       @Override
@@ -129,25 +130,27 @@ public Iterator<EndpointPair<N>> iterator() {
 
   @Override
   public boolean hasEdgeConnecting(N nodeU, N nodeV) {
-    return hasEdgeConnecting_internal(checkNotNull(nodeU), checkNotNull(nodeV));
+    return hasEdgeConnectingInternal(checkNotNull(nodeU), checkNotNull(nodeV));
   }
 
   @Override
   public boolean hasEdgeConnecting(EndpointPair<N> endpoints) {
     checkNotNull(endpoints);
     return isOrderingCompatible(endpoints)
-        && hasEdgeConnecting_internal(endpoints.nodeU(), endpoints.nodeV());
+        && hasEdgeConnectingInternal(endpoints.nodeU(), endpoints.nodeV());
   }
 
   @Override
-  public @Nullable V edgeValueOrDefault(N nodeU, N nodeV, @Nullable V defaultValue) {
-    return edgeValueOrDefault_internal(checkNotNull(nodeU), checkNotNull(nodeV), defaultValue);
+  @CheckForNull
+  public V edgeValueOrDefault(N nodeU, N nodeV, @CheckForNull V defaultValue) {
+    return edgeValueOrDefaultInternal(checkNotNull(nodeU), checkNotNull(nodeV), defaultValue);
   }
 
   @Override
-  public @Nullable V edgeValueOrDefault(EndpointPair<N> endpoints, @Nullable V defaultValue) {
+  @CheckForNull
+  public V edgeValueOrDefault(EndpointPair<N> endpoints, @CheckForNull V defaultValue) {
     validateEndpoints(endpoints);
-    return edgeValueOrDefault_internal(endpoints.nodeU(), endpoints.nodeV(), defaultValue);
+    return edgeValueOrDefaultInternal(endpoints.nodeU(), endpoints.nodeV(), defaultValue);
   }
 
   @Override
@@ -155,7 +158,7 @@ protected long edgeCount() {
     return edgeCount;
   }
 
-  protected final GraphConnections<N, V> checkedConnections(N node) {
+  private final GraphConnections<N, V> checkedConnections(N node) {
     GraphConnections<N, V> connections = nodeConnections.get(node);
     if (connections == null) {
       checkNotNull(node);
@@ -164,18 +167,24 @@ protected final GraphConnections<N, V> checkedConnections(N node) {
     return connections;
   }
 
-  protected final boolean containsNode(@Nullable N node) {
+  final boolean containsNode(@CheckForNull N node) {
     return nodeConnections.containsKey(node);
   }
 
-  protected final boolean hasEdgeConnecting_internal(N nodeU, N nodeV) {
+  private final boolean hasEdgeConnectingInternal(N nodeU, N nodeV) {
     GraphConnections<N, V> connectionsU = nodeConnections.get(nodeU);
     return (connectionsU != null) && connectionsU.successors().contains(nodeV);
   }
 
-  protected final V edgeValueOrDefault_internal(N nodeU, N nodeV, V defaultValue) {
+  @CheckForNull
+  private final V edgeValueOrDefaultInternal(N nodeU, N nodeV, @CheckForNull V defaultValue) {
     GraphConnections<N, V> connectionsU = nodeConnections.get(nodeU);
     V value = (connectionsU == null) ? null : connectionsU.value(nodeV);
-    return value == null ? defaultValue : value;
+    // TODO(b/192579700): Use a ternary once it no longer confuses our nullness checker.
+    if (value == null) {
+      return defaultValue;
+    } else {
+      return value;
+    }
   }
 }
diff --git a/guava/src/com/google/common/graph/SuccessorsFunction.java b/guava/src/com/google/common/graph/SuccessorsFunction.java
index f74f437c2937..c29bb4b94360 100644
--- a/guava/src/com/google/common/graph/SuccessorsFunction.java
+++ b/guava/src/com/google/common/graph/SuccessorsFunction.java
@@ -80,6 +80,7 @@
  */
 @Beta
 @DoNotMock("Implement with a lambda, or use GraphBuilder to build a Graph with the desired edges")
+@ElementTypesAreNonnullByDefault
 public interface SuccessorsFunction<N> {
 
   /**
diff --git a/guava/src/com/google/common/graph/Traverser.java b/guava/src/com/google/common/graph/Traverser.java
index b5e674950e5b..fb594b440365 100644
--- a/guava/src/com/google/common/graph/Traverser.java
+++ b/guava/src/com/google/common/graph/Traverser.java
@@ -18,6 +18,7 @@
 
 import static com.google.common.base.Preconditions.checkArgument;
 import static com.google.common.base.Preconditions.checkNotNull;
+import static java.util.Objects.requireNonNull;
 
 import com.google.common.annotations.Beta;
 import com.google.common.collect.AbstractIterator;
@@ -28,7 +29,7 @@
 import java.util.HashSet;
 import java.util.Iterator;
 import java.util.Set;
-import org.checkerframework.checker.nullness.qual.Nullable;
+import javax.annotation.CheckForNull;
 
 /**
  * An object that can traverse the nodes that are reachable from a specified (set of) start node(s)
@@ -63,6 +64,7 @@
 @DoNotMock(
     "Call forGraph or forTree, passing a lambda or a Graph with the desired edges (built with"
         + " GraphBuilder)")
+@ElementTypesAreNonnullByDefault
 public abstract class Traverser<N> {
   private final SuccessorsFunction<N> successorFunction;
 
@@ -94,7 +96,7 @@ private Traverser(SuccessorsFunction<N> successorFunction) {
    *
    * @param graph {@link SuccessorsFunction} representing a general graph that may have cycles.
    */
-  public static <N> Traverser<N> forGraph(final SuccessorsFunction<N> graph) {
+  public static <N> Traverser<N> forGraph(SuccessorsFunction<N> graph) {
     return new Traverser<N>(graph) {
       @Override
       Traversal<N> newTraversal() {
@@ -176,7 +178,7 @@ Traversal<N> newTraversal() {
    * @param tree {@link SuccessorsFunction} representing a directed acyclic graph that has at most
    *     one path between any two nodes
    */
-  public static <N> Traverser<N> forTree(final SuccessorsFunction<N> tree) {
+  public static <N> Traverser<N> forTree(SuccessorsFunction<N> tree) {
     if (tree instanceof BaseGraph) {
       checkArgument(((BaseGraph<?>) tree).isDirected(), "Undirected graphs can never be trees.");
     }
@@ -237,7 +239,7 @@ public final Iterable<N> breadthFirst(N startNode) {
    * @since 24.1
    */
   public final Iterable<N> breadthFirst(Iterable<? extends N> startNodes) {
-    final ImmutableSet<N> validated = validate(startNodes);
+    ImmutableSet<N> validated = validate(startNodes);
     return new Iterable<N>() {
       @Override
       public Iterator<N> iterator() {
@@ -292,7 +294,7 @@ public final Iterable<N> depthFirstPreOrder(N startNode) {
    * @since 24.1
    */
   public final Iterable<N> depthFirstPreOrder(Iterable<? extends N> startNodes) {
-    final ImmutableSet<N> validated = validate(startNodes);
+    ImmutableSet<N> validated = validate(startNodes);
     return new Iterable<N>() {
       @Override
       public Iterator<N> iterator() {
@@ -347,7 +349,7 @@ public final Iterable<N> depthFirstPostOrder(N startNode) {
    * @since 24.1
    */
   public final Iterable<N> depthFirstPostOrder(Iterable<? extends N> startNodes) {
-    final ImmutableSet<N> validated = validate(startNodes);
+    ImmutableSet<N> validated = validate(startNodes);
     return new Iterable<N>() {
       @Override
       public Iterator<N> iterator() {
@@ -380,13 +382,23 @@ private abstract static class Traversal<N> {
     }
 
     static <N> Traversal<N> inGraph(SuccessorsFunction<N> graph) {
-      final Set<N> visited = new HashSet<>();
+      Set<N> visited = new HashSet<>();
       return new Traversal<N>(graph) {
         @Override
+        @CheckForNull
         N visitNext(Deque<Iterator<? extends N>> horizon) {
           Iterator<? extends N> top = horizon.getFirst();
           while (top.hasNext()) {
-            N element = checkNotNull(top.next());
+            N element = top.next();
+            // requireNonNull is safe because horizon contains only graph nodes.
+            /*
+             * TODO(cpovirk): Replace these two statements with one (`N element =
+             * requireNonNull(top.next())`) once our checker supports it.
+             *
+             * (The problem is likely
+             * https://github.com/jspecify/nullness-checker-for-checker-framework/blob/61aafa4ae52594830cfc2d61c8b113009dbdb045/src/main/java/com/google/jspecify/nullness/NullSpecAnnotatedTypeFactory.java#L896)
+             */
+            requireNonNull(element);
             if (visited.add(element)) {
               return element;
             }
@@ -399,6 +411,7 @@ N visitNext(Deque<Iterator<? extends N>> horizon) {
 
     static <N> Traversal<N> inTree(SuccessorsFunction<N> tree) {
       return new Traversal<N>(tree) {
+        @CheckForNull
         @Override
         N visitNext(Deque<Iterator<? extends N>> horizon) {
           Iterator<? extends N> top = horizon.getFirst();
@@ -425,11 +438,12 @@ final Iterator<N> preOrder(Iterator<? extends N> startNodes) {
      * determined by the {@code InsertionOrder} parameter: nieces are placed at the FRONT before
      * aunts for pre-order; while in BFS they are placed at the BACK after aunts.
      */
-    private Iterator<N> topDown(Iterator<? extends N> startNodes, final InsertionOrder order) {
-      final Deque<Iterator<? extends N>> horizon = new ArrayDeque<>();
+    private Iterator<N> topDown(Iterator<? extends N> startNodes, InsertionOrder order) {
+      Deque<Iterator<? extends N>> horizon = new ArrayDeque<>();
       horizon.add(startNodes);
       return new AbstractIterator<N>() {
         @Override
+        @CheckForNull
         protected N computeNext() {
           do {
             N next = visitNext(horizon);
@@ -449,11 +463,12 @@ protected N computeNext() {
     }
 
     final Iterator<N> postOrder(Iterator<? extends N> startNodes) {
-      final Deque<N> ancestorStack = new ArrayDeque<>();
-      final Deque<Iterator<? extends N>> horizon = new ArrayDeque<>();
+      Deque<N> ancestorStack = new ArrayDeque<>();
+      Deque<Iterator<? extends N>> horizon = new ArrayDeque<>();
       horizon.add(startNodes);
       return new AbstractIterator<N>() {
         @Override
+        @CheckForNull
         protected N computeNext() {
           for (N next = visitNext(horizon); next != null; next = visitNext(horizon)) {
             Iterator<? extends N> successors = successorFunction.successors(next).iterator();
@@ -463,7 +478,11 @@ protected N computeNext() {
             horizon.addFirst(successors);
             ancestorStack.push(next);
           }
-          return ancestorStack.isEmpty() ? endOfData() : ancestorStack.pop();
+          // TODO(b/192579700): Use a ternary once it no longer confuses our nullness checker.
+          if (!ancestorStack.isEmpty()) {
+            return ancestorStack.pop();
+          }
+          return endOfData();
         }
       };
     }
@@ -478,7 +497,8 @@ protected N computeNext() {
      * into {@code horizon} between calls to {@code visitNext()}. This causes them to receive
      * additional values interleaved with those shown above.)
      */
-    abstract @Nullable N visitNext(Deque<Iterator<? extends N>> horizon);
+    @CheckForNull
+    abstract N visitNext(Deque<Iterator<? extends N>> horizon);
   }
 
   /** Poor man's method reference for {@code Deque::addFirst} and {@code Deque::addLast}. */
diff --git a/guava/src/com/google/common/graph/UndirectedGraphConnections.java b/guava/src/com/google/common/graph/UndirectedGraphConnections.java
index 49689f9d8aec..4eeb2328fe0e 100644
--- a/guava/src/com/google/common/graph/UndirectedGraphConnections.java
+++ b/guava/src/com/google/common/graph/UndirectedGraphConnections.java
@@ -20,7 +20,6 @@
 import static com.google.common.graph.GraphConstants.INNER_CAPACITY;
 import static com.google.common.graph.GraphConstants.INNER_LOAD_FACTOR;
 
-import com.google.common.base.Function;
 import com.google.common.collect.ImmutableMap;
 import com.google.common.collect.Iterators;
 import java.util.Collections;
@@ -29,6 +28,7 @@
 import java.util.LinkedHashMap;
 import java.util.Map;
 import java.util.Set;
+import javax.annotation.CheckForNull;
 
 /**
  * An implementation of {@link GraphConnections} for undirected graphs.
@@ -37,6 +37,7 @@
  * @param <N> Node parameter type
  * @param <V> Value parameter type
  */
+@ElementTypesAreNonnullByDefault
 final class UndirectedGraphConnections<N, V> implements GraphConnections<N, V> {
   private final Map<N, V> adjacentNodeValues;
 
@@ -77,18 +78,14 @@ public Set<N> successors() {
   }
 
   @Override
-  public Iterator<EndpointPair<N>> incidentEdgeIterator(final N thisNode) {
+  public Iterator<EndpointPair<N>> incidentEdgeIterator(N thisNode) {
     return Iterators.transform(
         adjacentNodeValues.keySet().iterator(),
-        new Function<N, EndpointPair<N>>() {
-          @Override
-          public EndpointPair<N> apply(N incidentNode) {
-            return EndpointPair.unordered(thisNode, incidentNode);
-          }
-        });
+        (N incidentNode) -> EndpointPair.unordered(thisNode, incidentNode));
   }
 
   @Override
+  @CheckForNull
   public V value(N node) {
     return adjacentNodeValues.get(node);
   }
@@ -100,6 +97,7 @@ public void removePredecessor(N node) {
   }
 
   @Override
+  @CheckForNull
   public V removeSuccessor(N node) {
     return adjacentNodeValues.remove(node);
   }
@@ -111,6 +109,7 @@ public void addPredecessor(N node, V value) {
   }
 
   @Override
+  @CheckForNull
   public V addSuccessor(N node, V value) {
     return adjacentNodeValues.put(node, value);
   }
diff --git a/guava/src/com/google/common/graph/UndirectedMultiNetworkConnections.java b/guava/src/com/google/common/graph/UndirectedMultiNetworkConnections.java
index a96a59593e39..6caac3b715dd 100644
--- a/guava/src/com/google/common/graph/UndirectedMultiNetworkConnections.java
+++ b/guava/src/com/google/common/graph/UndirectedMultiNetworkConnections.java
@@ -30,7 +30,7 @@
 import java.util.HashMap;
 import java.util.Map;
 import java.util.Set;
-import org.checkerframework.checker.nullness.qual.Nullable;
+import javax.annotation.CheckForNull;
 
 /**
  * An implementation of {@link NetworkConnections} for undirected networks with parallel edges.
@@ -39,6 +39,7 @@
  * @param <N> Node parameter type
  * @param <E> Edge parameter type
  */
+@ElementTypesAreNonnullByDefault
 final class UndirectedMultiNetworkConnections<N, E>
     extends AbstractUndirectedNetworkConnections<N, E> {
 
@@ -55,7 +56,7 @@ static <N, E> UndirectedMultiNetworkConnections<N, E> ofImmutable(Map<E, N> inci
     return new UndirectedMultiNetworkConnections<>(ImmutableMap.copyOf(incidentEdges));
   }
 
-  @LazyInit private transient Reference<Multiset<N>> adjacentNodesReference;
+  @CheckForNull @LazyInit private transient Reference<Multiset<N>> adjacentNodesReference;
 
   @Override
   public Set<N> adjacentNodes() {
@@ -72,7 +73,7 @@ private Multiset<N> adjacentNodesMultiset() {
   }
 
   @Override
-  public Set<E> edgesConnecting(final N node) {
+  public Set<E> edgesConnecting(N node) {
     return new MultiEdgesConnecting<E>(incidentEdgeMap, node) {
       @Override
       public int size() {
@@ -82,6 +83,7 @@ public int size() {
   }
 
   @Override
+  @CheckForNull
   public N removeInEdge(E edge, boolean isSelfLoop) {
     if (!isSelfLoop) {
       return removeOutEdge(edge);
@@ -115,7 +117,8 @@ public void addOutEdge(E edge, N node) {
     }
   }
 
-  private static <T> @Nullable T getReference(@Nullable Reference<T> reference) {
+  @CheckForNull
+  private static <T> T getReference(@CheckForNull Reference<T> reference) {
     return (reference == null) ? null : reference.get();
   }
 }
diff --git a/guava/src/com/google/common/graph/UndirectedNetworkConnections.java b/guava/src/com/google/common/graph/UndirectedNetworkConnections.java
index 1e253dd05703..190897f8825d 100644
--- a/guava/src/com/google/common/graph/UndirectedNetworkConnections.java
+++ b/guava/src/com/google/common/graph/UndirectedNetworkConnections.java
@@ -32,9 +32,10 @@
  * @param <N> Node parameter type
  * @param <E> Edge parameter type
  */
+@ElementTypesAreNonnullByDefault
 final class UndirectedNetworkConnections<N, E> extends AbstractUndirectedNetworkConnections<N, E> {
 
-  protected UndirectedNetworkConnections(Map<E, N> incidentEdgeMap) {
+  UndirectedNetworkConnections(Map<E, N> incidentEdgeMap) {
     super(incidentEdgeMap);
   }
 
@@ -53,6 +54,6 @@ public Set<N> adjacentNodes() {
 
   @Override
   public Set<E> edgesConnecting(N node) {
-    return new EdgesConnecting<E>(((BiMap<E, N>) incidentEdgeMap).inverse(), node);
+    return new EdgesConnecting<>(((BiMap<E, N>) incidentEdgeMap).inverse(), node);
   }
 }
diff --git a/guava/src/com/google/common/graph/ValueGraph.java b/guava/src/com/google/common/graph/ValueGraph.java
index ed27058fb1e5..a13e87eb9833 100644
--- a/guava/src/com/google/common/graph/ValueGraph.java
+++ b/guava/src/com/google/common/graph/ValueGraph.java
@@ -20,7 +20,7 @@
 import java.util.Collection;
 import java.util.Optional;
 import java.util.Set;
-import org.checkerframework.checker.nullness.qual.Nullable;
+import javax.annotation.CheckForNull;
 
 /**
  * An interface for <a
@@ -108,6 +108,7 @@
  * @since 20.0
  */
 @Beta
+@ElementTypesAreNonnullByDefault
 public interface ValueGraph<N, V> extends BaseGraph<N> {
   //
   // ValueGraph-level accessors
@@ -309,8 +310,8 @@ public interface ValueGraph<N, V> extends BaseGraph<N> {
    * @throws IllegalArgumentException if {@code nodeU} or {@code nodeV} is not an element of this
    *     graph
    */
-  @Nullable
-  V edgeValueOrDefault(N nodeU, N nodeV, @Nullable V defaultValue);
+  @CheckForNull
+  V edgeValueOrDefault(N nodeU, N nodeV, @CheckForNull V defaultValue);
 
   /**
    * Returns the value of the edge that connects {@code endpoints} (in the order, if any, specified
@@ -322,8 +323,8 @@ public interface ValueGraph<N, V> extends BaseGraph<N> {
    * @throws IllegalArgumentException if the endpoints are unordered and the graph is directed
    * @since 27.1
    */
-  @Nullable
-  V edgeValueOrDefault(EndpointPair<N> endpoints, @Nullable V defaultValue);
+  @CheckForNull
+  V edgeValueOrDefault(EndpointPair<N> endpoints, @CheckForNull V defaultValue);
 
   //
   // ValueGraph identity
@@ -350,7 +351,7 @@ public interface ValueGraph<N, V> extends BaseGraph<N> {
    * <p>A reference implementation of this is provided by {@link AbstractValueGraph#equals(Object)}.
    */
   @Override
-  boolean equals(@Nullable Object object);
+  boolean equals(@CheckForNull Object object);
 
   /**
    * Returns the hash code for this graph. The hash code of a graph is defined as the hash code of a
diff --git a/guava/src/com/google/common/graph/ValueGraphBuilder.java b/guava/src/com/google/common/graph/ValueGraphBuilder.java
index 4fc752da1f4a..ce146c325504 100644
--- a/guava/src/com/google/common/graph/ValueGraphBuilder.java
+++ b/guava/src/com/google/common/graph/ValueGraphBuilder.java
@@ -66,6 +66,7 @@
  * @since 20.0
  */
 @Beta
+@ElementTypesAreNonnullByDefault
 public final class ValueGraphBuilder<N, V> extends AbstractGraphBuilder<N> {
 
   /** Creates a new instance with the specified edge directionality. */
diff --git a/guava/src/com/google/common/hash/AbstractByteHasher.java b/guava/src/com/google/common/hash/AbstractByteHasher.java
index 7097c39b89a3..9ac0acd6da0a 100644
--- a/guava/src/com/google/common/hash/AbstractByteHasher.java
+++ b/guava/src/com/google/common/hash/AbstractByteHasher.java
@@ -36,13 +36,14 @@
  * @author Colin Decker
  */
 @CanIgnoreReturnValue
+@ElementTypesAreNonnullByDefault
 abstract class AbstractByteHasher extends AbstractHasher {
   private final ByteBuffer scratch = ByteBuffer.allocate(8).order(ByteOrder.LITTLE_ENDIAN);
 
   /** Updates this hasher with the given byte. */
   protected abstract void update(byte b);
 
-  @SuppressWarnings("upperbound:argument.type.incompatible")// `0 + b.length - 1` is < b.length.
+  @SuppressWarnings("upperbound:argument")// `0 + b.length - 1` is < b.length.
   /** Updates this hasher with the given bytes. */
   protected void update(byte[] b) {
     update(b, 0, b.length);
@@ -56,7 +57,7 @@ protected void update(byte[] b, @NonNegative @LTLengthOf(value = "#1",offset = "
   }
 
   /** Updates this hasher with bytes from the given buffer. */
-  @SuppressWarnings({"lowerbound:argument.type.incompatible","upperbound:argument.type.incompatible"})/*
+  @SuppressWarnings({"lowerbound:argument","upperbound:argument"}) /*
   Invariants: position <= limit <= capacity( is length of buffer).
   Since `b.remaining()` return limit - position, and `b.arrayOffset() + b.position()`
   return offset("buffer's backing array of the first element of the buffer")  + position,
@@ -73,7 +74,7 @@ protected void update(ByteBuffer b) {
   }
 
   /** Updates the sink with the given number of bytes from the buffer. */
-  @SuppressWarnings({"upperbound:argument.type.incompatible","lowerbound:argument.type.incompatible"})/*
+  @SuppressWarnings({"upperbound:argument"}) /*
   Since `ByteBuffer scratch = ByteBuffer.allocate(8).order(ByteOrder.LITTLE_ENDIAN);`, scratch.array() will
   return an array with length of 8.
   */
diff --git a/guava/src/com/google/common/hash/AbstractCompositeHashFunction.java b/guava/src/com/google/common/hash/AbstractCompositeHashFunction.java
index 206078d7f3e3..76169bcbe63d 100644
--- a/guava/src/com/google/common/hash/AbstractCompositeHashFunction.java
+++ b/guava/src/com/google/common/hash/AbstractCompositeHashFunction.java
@@ -23,6 +23,7 @@
 import org.checkerframework.common.value.qual.MinLen;
 import java.nio.ByteBuffer;
 import java.nio.charset.Charset;
+import org.checkerframework.checker.nullness.qual.Nullable;
 
 /**
  * An abstract composition of multiple hash functions. {@linkplain #newHasher()} delegates to the
@@ -32,6 +33,7 @@
  * @author Dimitris Andreou
  */
 @Immutable
+@ElementTypesAreNonnullByDefault
 abstract class AbstractCompositeHashFunction extends AbstractHashFunction {
 
   @SuppressWarnings("Immutable") // array not modified after creation
@@ -71,7 +73,7 @@ public Hasher newHasher(@NonNegative int expectedInputSize) {
     return fromHashers(hashers);
   }
 
-  private Hasher fromHashers(final Hasher[] hashers) {
+  private Hasher fromHashers(Hasher[] hashers) {
     return new Hasher() {
       @Override
       public Hasher putByte(byte b) {
@@ -180,7 +182,8 @@ public Hasher putString(@MinLen(1) CharSequence chars, Charset charset) {
       }
 
       @Override
-      public <T> Hasher putObject(T instance, Funnel<? super T> funnel) {
+      public <T extends @Nullable Object> Hasher putObject(
+          @ParametricNullness T instance, Funnel<? super T> funnel) {
         for (Hasher hasher : hashers) {
           hasher.putObject(instance, funnel);
         }
diff --git a/guava/src/com/google/common/hash/AbstractHashFunction.java b/guava/src/com/google/common/hash/AbstractHashFunction.java
index 918e7a97d1c8..245f25dd0e00 100644
--- a/guava/src/com/google/common/hash/AbstractHashFunction.java
+++ b/guava/src/com/google/common/hash/AbstractHashFunction.java
@@ -24,6 +24,7 @@
 import org.checkerframework.common.value.qual.MinLen;
 import java.nio.ByteBuffer;
 import java.nio.charset.Charset;
+import org.checkerframework.checker.nullness.qual.Nullable;
 
 /**
  * Skeleton implementation of {@link HashFunction} in terms of {@link #newHasher()}.
@@ -31,15 +32,14 @@
  * <p>TODO(lowasser): make public
  */
 @Immutable
+@ElementTypesAreNonnullByDefault
 abstract class AbstractHashFunction implements HashFunction {
   @Override
-  public <T> HashCode hashObject(T instance, Funnel<? super T> funnel) {
+  public <T extends @Nullable Object> HashCode hashObject(
+      @ParametricNullness T instance, Funnel<? super T> funnel) {
     return newHasher().putObject(instance, funnel).hash();
   }
 
-  @SuppressWarnings({"lowerbound:argument.type.incompatible",// Since len is length of `input` with min length of 1,
-          // len * 2 can't be negative
-  })
   @Override
   public HashCode hashUnencodedChars(@MinLen(1) CharSequence input) {
     int len = input.length();
@@ -61,7 +61,7 @@ public HashCode hashLong(long input) {
     return newHasher(8).putLong(input).hash();
   }
 
-  @SuppressWarnings("upperbound:argument.type.incompatible")// If input has min length of 1, since off is 0, off + input.length - 1 is always < input.length.
+  @SuppressWarnings("upperbound:argument") // If input has min length of 1, since off is 0, off + input.length - 1 is always < input.length.
   @Override
   public HashCode hashBytes(byte @MinLen(1)[] input) {
     return hashBytes(input, 0, input.length);
diff --git a/guava/src/com/google/common/hash/AbstractHasher.java b/guava/src/com/google/common/hash/AbstractHasher.java
index 8d658827c243..caa338e14470 100644
--- a/guava/src/com/google/common/hash/AbstractHasher.java
+++ b/guava/src/com/google/common/hash/AbstractHasher.java
@@ -20,6 +20,7 @@
 import java.nio.charset.Charset;
 import org.checkerframework.checker.index.qual.LTLengthOf;
 import org.checkerframework.checker.index.qual.NonNegative;
+import org.checkerframework.checker.nullness.qual.Nullable;
 import org.checkerframework.common.value.qual.MinLen;
 
 /**
@@ -29,6 +30,7 @@
  * @author Dimitris Andreou
  */
 @CanIgnoreReturnValue
+@ElementTypesAreNonnullByDefault
 abstract class AbstractHasher implements Hasher {
   @Override
   public final Hasher putBoolean(boolean b) {
@@ -120,7 +122,8 @@ public Hasher putChar(char c) {
   }
 
   @Override
-  public <T> Hasher putObject(T instance, Funnel<? super T> funnel) {
+  public <T extends @Nullable Object> Hasher putObject(
+      @ParametricNullness T instance, Funnel<? super T> funnel) {
     funnel.funnel(instance, this);
     return this;
   }
diff --git a/guava/src/com/google/common/hash/AbstractNonStreamingHashFunction.java b/guava/src/com/google/common/hash/AbstractNonStreamingHashFunction.java
index 80af6d3ed278..8f9e3db01012 100644
--- a/guava/src/com/google/common/hash/AbstractNonStreamingHashFunction.java
+++ b/guava/src/com/google/common/hash/AbstractNonStreamingHashFunction.java
@@ -34,6 +34,7 @@
  * @author Dimitris Andreou
  */
 @Immutable
+@ElementTypesAreNonnullByDefault
 abstract class AbstractNonStreamingHashFunction extends AbstractHashFunction {
   @Override
   public Hasher newHasher() {
@@ -85,9 +86,6 @@ public HashCode hashString(@MinLen(1) CharSequence input, Charset charset) {
   @Override
   public abstract HashCode hashBytes(byte[] input, @NonNegative @LTLengthOf(value = "#1", offset = "#3 - 1") int off, @LTLengthOf(value = "#1", offset = "#2 - 1") int len);
 
-  @SuppressWarnings("lowerbound:argument.type.incompatible")/* Since invariants: mark <= position <= limit <= capacity,
-  and position is initialized as 0, `input.remaining()` return `limit - position` with lowest possible value as 0.
-  */
   @Override
   public HashCode hashBytes(ByteBuffer input) {
     return newHasher(input.remaining()).putBytes(input).hash();
@@ -108,6 +106,7 @@ public Hasher putByte(byte b) {
     }
 
     @Override
+    @SuppressWarnings("index:argument")
     public Hasher putBytes(byte[] bytes, @NonNegative @LTLengthOf(value = "#1", offset = "#3 - 1") int off, @NonNegative @LTLengthOf(value = "#1", offset = "#2 - 1") int len) {
       stream.write(bytes, off, len);
       return this;
@@ -119,10 +118,10 @@ public Hasher putBytes(ByteBuffer bytes) {
       return this;
     }
 
-    @SuppressWarnings(value = {"upperbound:argument.type.incompatible",// `stream.byteArray()` return an array of length 32
+    @SuppressWarnings({
+        "upperbound:argument", // `stream.byteArray()` return an array of length 32
             // Since `stream.length()` return the length of return byte array, 0 + stream.length - 1 is always < stream.length.
-            "lowerbound:argument.type.incompatible"/*`stream.length` returns `count` of the pre-compiled class `ByteArrayOutputStream`.
-            therefore, `count` should be annotated as @NonNegative in `ByteArrayOutputStream` */})
+    })
     @Override
     public HashCode hash() {
       return hashBytes(stream.byteArray(), 0, stream.length());
@@ -135,8 +134,7 @@ private static final class ExposedByteArrayOutputStream extends ByteArrayOutputS
       super(expectedInputSize);
     }
 
-    @SuppressWarnings({"lowerbound:argument.type.incompatible", "lowerbound:assignment.type.incompatible"})/* Since invariants: position <= limit <= capacity,
-    and position is initialized as 0, `input.remaining()` return `limit - position` with lowest possible value as 0. */
+    @SuppressWarnings({"index:compound.assignment"})
     void write(ByteBuffer input) {
       @NonNegative int remaining = input.remaining();
       if (count + remaining > buf.length) {
diff --git a/guava/src/com/google/common/hash/AbstractStreamingHasher.java b/guava/src/com/google/common/hash/AbstractStreamingHasher.java
index 67de74baf599..a987b48c35f7 100644
--- a/guava/src/com/google/common/hash/AbstractStreamingHasher.java
+++ b/guava/src/com/google/common/hash/AbstractStreamingHasher.java
@@ -29,6 +29,7 @@
  */
 // TODO(kevinb): this class still needs some design-and-document-for-inheritance love
 @CanIgnoreReturnValue
+@ElementTypesAreNonnullByDefault
 abstract class AbstractStreamingHasher extends AbstractHasher {
   /** Buffer via which we pass data to the hash algorithm (the implementor) */
   private final ByteBuffer buffer;
diff --git a/guava/src/com/google/common/hash/BloomFilter.java b/guava/src/com/google/common/hash/BloomFilter.java
index c3f61de6ffa6..e7e6ba96f403 100644
--- a/guava/src/com/google/common/hash/BloomFilter.java
+++ b/guava/src/com/google/common/hash/BloomFilter.java
@@ -23,6 +23,7 @@
 import com.google.common.base.Predicate;
 import com.google.common.hash.BloomFilterStrategies.LockFreeBitArray;
 import com.google.common.math.DoubleMath;
+import com.google.common.math.LongMath;
 import com.google.common.primitives.SignedBytes;
 import com.google.common.primitives.UnsignedBytes;
 import com.google.errorprone.annotations.CanIgnoreReturnValue;
@@ -34,6 +35,7 @@
 import java.io.Serializable;
 import java.math.RoundingMode;
 import java.util.stream.Collector;
+import javax.annotation.CheckForNull;
 import org.checkerframework.checker.index.qual.LessThan;
 import org.checkerframework.checker.index.qual.NonNegative;
 import org.checkerframework.checker.index.qual.Positive;
@@ -46,7 +48,7 @@
  * but if it claims that an element is <i>not</i> contained in it, then this is definitely true.
  *
  * <p>If you are unfamiliar with Bloom filters, this nice <a
- * href="http://llimllib.github.com/bloomfilter-tutorial/">tutorial</a> may help you understand how
+ * href="http://llimllib.github.io/bloomfilter-tutorial/">tutorial</a> may help you understand how
  * they work.
  *
  * <p>The false positive probability ({@code FPP}) of a Bloom filter is defined as the probability
@@ -68,7 +70,8 @@
  * @since 11.0 (thread-safe since 23.0)
  */
 @Beta
-public final class BloomFilter<T> implements Predicate<T>, Serializable {
+@ElementTypesAreNonnullByDefault
+public final class BloomFilter<T extends @Nullable Object> implements Predicate<T>, Serializable {
   /**
    * A strategy to translate T instances, to {@code numHashFunctions} bit indexes.
    *
@@ -81,15 +84,21 @@ interface Strategy extends java.io.Serializable {
      *
      * <p>Returns whether any bits changed as a result of this operation.
      */
-    <T> boolean put(
-        T object, Funnel<? super T> funnel, int numHashFunctions, LockFreeBitArray bits);
+    <T extends @Nullable Object> boolean put(
+        @ParametricNullness T object,
+        Funnel<? super T> funnel,
+        int numHashFunctions,
+        LockFreeBitArray bits);
 
     /**
      * Queries {@code numHashFunctions} bits of the given bit array, by hashing a user element;
      * returns {@code true} if and only if all selected bits are set.
      */
-    <T> boolean mightContain(
-        T object, Funnel<? super T> funnel, int numHashFunctions, LockFreeBitArray bits);
+    <T extends @Nullable Object> boolean mightContain(
+        @ParametricNullness T object,
+        Funnel<? super T> funnel,
+        int numHashFunctions,
+        LockFreeBitArray bits);
 
     /**
      * Identifier used to encode this strategy, when marshalled as part of a BloomFilter. Only
@@ -114,7 +123,6 @@ <T> boolean mightContain(
   private final Strategy strategy;
 
   /** Creates a BloomFilter. */
-  @SuppressWarnings("upperbound:assignment.type.incompatible")//if `numHashFunctions > 255`, check argument throws an error message
   private BloomFilter(
       LockFreeBitArray bits, @IntRange(from = 0, to = 255) int numHashFunctions, Funnel<? super T> funnel, Strategy strategy) {
     checkArgument(numHashFunctions > 0, "numHashFunctions (%s) must be > 0", numHashFunctions);
@@ -140,7 +148,7 @@ public BloomFilter<T> copy() {
    * Returns {@code true} if the element <i>might</i> have been put in this Bloom filter, {@code
    * false} if this is <i>definitely</i> not the case.
    */
-  public boolean mightContain(T object) {
+  public boolean mightContain(@ParametricNullness T object) {
     return strategy.mightContain(object, funnel, numHashFunctions, bits);
   }
 
@@ -150,7 +158,7 @@ public boolean mightContain(T object) {
    */
   @Deprecated
   @Override
-  public boolean apply(T input) {
+  public boolean apply(@ParametricNullness T input) {
     return mightContain(input);
   }
 
@@ -166,7 +174,7 @@ public boolean apply(T input) {
    * @since 12.0 (present in 11.0 with {@code void} return type})
    */
   @CanIgnoreReturnValue
-  public boolean put(T object) {
+  public boolean put(@ParametricNullness T object) {
     return strategy.put(object, funnel, numHashFunctions, bits);
   }
 
@@ -273,7 +281,7 @@ public void putAll(BloomFilter<T> that) {
   }
 
   @Override
-  public boolean equals(@Nullable Object object) {
+  public boolean equals(@CheckForNull Object object) {
     if (object == this) {
       return true;
     }
@@ -313,7 +321,7 @@ public int hashCode() {
    * @return a {@code Collector} generating a {@code BloomFilter} of the received elements
    * @since 23.0
    */
-  public static <T> Collector<T, ?, BloomFilter<T>> toBloomFilter(
+  public static <T extends @Nullable Object> Collector<T, ?, BloomFilter<T>> toBloomFilter(
       Funnel<? super T> funnel, @Positive long expectedInsertions) {
     return toBloomFilter(funnel, expectedInsertions, 0.03);
   }
@@ -340,7 +348,7 @@ public int hashCode() {
    * @return a {@code Collector} generating a {@code BloomFilter} of the received elements
    * @since 23.0
    */
-  public static <T> Collector<T, ?, BloomFilter<T>> toBloomFilter(
+  public static <T extends @Nullable Object> Collector<T, ?, BloomFilter<T>> toBloomFilter(
       Funnel<? super T> funnel, @Positive long expectedInsertions, @NonNegative double fpp) {
     checkNotNull(funnel);
     checkArgument(
@@ -378,7 +386,7 @@ public int hashCode() {
    * @param fpp the desired false positive probability (must be positive and less than 1.0)
    * @return a {@code BloomFilter}
    */
-  public static <T> BloomFilter<T> create(
+  public static <T extends @Nullable Object> BloomFilter<T> create(
       Funnel<? super T> funnel, @Positive int expectedInsertions, @NonNegative @LessThan("1") double fpp) {
     return create(funnel, (long) expectedInsertions, fpp);
   }
@@ -404,13 +412,13 @@ public static <T> BloomFilter<T> create(
    * @return a {@code BloomFilter}
    * @since 19.0
    */
-  public static <T> BloomFilter<T> create(
+  public static <T extends @Nullable Object> BloomFilter<T> create(
       Funnel<? super T> funnel, @Positive long expectedInsertions, @NonNegative double fpp) {
     return create(funnel, expectedInsertions, fpp, BloomFilterStrategies.MURMUR128_MITZ_64);
   }
 
   @VisibleForTesting
-  static <T> BloomFilter<T> create(
+  static <T extends @Nullable Object> BloomFilter<T> create(
       Funnel<? super T> funnel, @NonNegative long expectedInsertions, @NonNegative double fpp, Strategy strategy) {
     checkNotNull(funnel);
     checkArgument(
@@ -455,7 +463,8 @@ static <T> BloomFilter<T> create(
    *     BloomFilter}; must be positive
    * @return a {@code BloomFilter}
    */
-  public static <T> BloomFilter<T> create(Funnel<? super T> funnel, @Positive int expectedInsertions) {
+  public static <T extends @Nullable Object> BloomFilter<T> create(
+      Funnel<? super T> funnel, @Positive int expectedInsertions) {
     return create(funnel, (long) expectedInsertions);
   }
 
@@ -479,7 +488,8 @@ public static <T> BloomFilter<T> create(Funnel<? super T> funnel, @Positive int
    * @return a {@code BloomFilter}
    * @since 19.0
    */
-  public static <T> BloomFilter<T> create(Funnel<? super T> funnel, @Positive long expectedInsertions) {
+  public static <T extends @Nullable Object> BloomFilter<T> create(
+      Funnel<? super T> funnel, @Positive long expectedInsertions) {
     return create(funnel, expectedInsertions, 0.03); // FYI, for 3%, we always get 5 hash functions
   }
 
@@ -505,7 +515,7 @@ public static <T> BloomFilter<T> create(Funnel<? super T> funnel, @Positive long
    * @param m total number of bits in Bloom filter (must be positive)
    */
   @VisibleForTesting
-  @SuppressWarnings("value:return.type.incompatible")
+  @SuppressWarnings("value:return")
   static @IntRange(from = 0, to = 255) int optimalNumOfHashFunctions(@Positive long n, @Positive long m) {
     // (m / n) * log(2), but avoid truncation due to division!
     return Math.max(1, (int) Math.round((double) m / n * Math.log(2)));
@@ -533,7 +543,7 @@ private Object writeReplace() {
     return new SerialForm<T>(this);
   }
 
-  private static class SerialForm<T> implements Serializable {
+  private static class SerialForm<T extends @Nullable Object> implements Serializable {
     final long[] data;
     final @IntRange(from = 0, to = 255) int numHashFunctions;
     final Funnel<? super T> funnel;
@@ -586,8 +596,13 @@ public void writeTo(OutputStream out) throws IOException {
    * @throws IOException if the InputStream throws an {@code IOException}, or if its data does not
    *     appear to be a BloomFilter serialized using the {@linkplain #writeTo(OutputStream)} method.
    */
-  public static <T> BloomFilter<T> readFrom(InputStream in, Funnel<? super T> funnel)
-      throws IOException {
+  @SuppressWarnings({
+      "value:argument",
+      "lowerbound:array.access.unsafe.low",
+      "upperbound:array.access.unsafe.high",
+  })
+  public static <T extends @Nullable Object> BloomFilter<T> readFrom(
+      InputStream in, Funnel<? super T> funnel) throws IOException {
     checkNotNull(in, "InputStream");
     checkNotNull(funnel, "Funnel");
     int strategyOrdinal = -1;
@@ -603,11 +618,13 @@ public static <T> BloomFilter<T> readFrom(InputStream in, Funnel<? super T> funn
       dataLength = din.readInt();
 
       Strategy strategy = BloomFilterStrategies.values()[strategyOrdinal];
-      long[] data = new long[dataLength];
-      for (int i = 0; i < data.length; i++) {
-        data[i] = din.readLong();
+
+      LockFreeBitArray dataArray = new LockFreeBitArray(LongMath.checkedMultiply(dataLength, 64L));
+      for (int i = 0; i < dataLength; i++) {
+        dataArray.putData(i, din.readLong());
       }
-      return new BloomFilter<T>(new LockFreeBitArray(data), numHashFunctions, funnel, strategy);
+
+      return new BloomFilter<T>(dataArray, numHashFunctions, funnel, strategy);
     } catch (RuntimeException e) {
       String message =
           "Unable to deserialize BloomFilter from InputStream."
diff --git a/guava/src/com/google/common/hash/BloomFilterStrategies.java b/guava/src/com/google/common/hash/BloomFilterStrategies.java
index 46a5ae81520b..662a41890904 100644
--- a/guava/src/com/google/common/hash/BloomFilterStrategies.java
+++ b/guava/src/com/google/common/hash/BloomFilterStrategies.java
@@ -22,6 +22,7 @@
 import java.math.RoundingMode;
 import java.util.Arrays;
 import java.util.concurrent.atomic.AtomicLongArray;
+import javax.annotation.CheckForNull;
 import org.checkerframework.checker.nullness.qual.Nullable;
 import org.checkerframework.common.value.qual.IntRange;
 import org.checkerframework.common.value.qual.MinLen;
@@ -38,6 +39,7 @@
  * @author Dimitris Andreou
  * @author Kurt Alfred Kluever
  */
+@ElementTypesAreNonnullByDefault
 enum BloomFilterStrategies implements BloomFilter.Strategy {
   /**
    * See "Less Hashing, Same Performance: Building a Better Bloom Filter" by Adam Kirsch and Michael
@@ -46,8 +48,11 @@ enum BloomFilterStrategies implements BloomFilter.Strategy {
    */
   MURMUR128_MITZ_32() {
     @Override
-    public <T> boolean put(
-        T object, Funnel<? super T> funnel, int numHashFunctions, LockFreeBitArray bits) {
+    public <T extends @Nullable Object> boolean put(
+        @ParametricNullness T object,
+        Funnel<? super T> funnel,
+        int numHashFunctions,
+        LockFreeBitArray bits) {
       long bitSize = bits.bitSize();
       long hash64 = Hashing.murmur3_128().hashObject(object, funnel).asLong();
       int hash1 = (int) hash64;
@@ -66,8 +71,11 @@ public <T> boolean put(
     }
 
     @Override
-    public <T> boolean mightContain(
-        T object, Funnel<? super T> funnel, int numHashFunctions, LockFreeBitArray bits) {
+    public <T extends @Nullable Object> boolean mightContain(
+        @ParametricNullness T object,
+        Funnel<? super T> funnel,
+        int numHashFunctions,
+        LockFreeBitArray bits) {
       long bitSize = bits.bitSize();
       long hash64 = Hashing.murmur3_128().hashObject(object, funnel).asLong();
       int hash1 = (int) hash64;
@@ -94,9 +102,13 @@ public <T> boolean mightContain(
    */
   MURMUR128_MITZ_64() {
     @Override
-    public <T> boolean put(
-        T object, Funnel<? super T> funnel, int numHashFunctions, LockFreeBitArray bits) {
+    public <T extends @Nullable Object> boolean put(
+        @ParametricNullness T object,
+        Funnel<? super T> funnel,
+        int numHashFunctions,
+        LockFreeBitArray bits) {
       long bitSize = bits.bitSize();
+      @SuppressWarnings("value:assignment")
       byte @MinLen(16)[] bytes = Hashing.murmur3_128().hashObject(object, funnel).getBytesInternal();
       long hash1 = lowerEight(bytes);
       long hash2 = upperEight(bytes);
@@ -112,9 +124,13 @@ public <T> boolean put(
     }
 
     @Override
-    public <T> boolean mightContain(
-        T object, Funnel<? super T> funnel, int numHashFunctions, LockFreeBitArray bits) {
+    public <T extends @Nullable Object> boolean mightContain(
+        @ParametricNullness T object,
+        Funnel<? super T> funnel,
+        int numHashFunctions,
+        LockFreeBitArray bits) {
       long bitSize = bits.bitSize();
+      @SuppressWarnings("value:assignment")
       byte @MinLen(16)[] bytes = Hashing.murmur3_128().hashObject(object, funnel).getBytesInternal();
       long hash1 = lowerEight(bytes);
       long hash2 = upperEight(bytes);
@@ -147,12 +163,8 @@ public <T> boolean mightContain(
    * <p>We use this instead of java.util.BitSet because we need access to the array of longs and we
    * need compare-and-swap.
    */
-  @SuppressWarnings({"lowerbound:array.length.negative",// Since `Ints.checkedCast` return the int value that is equal to non negative`long bits`,
+  @SuppressWarnings("value:argument") // Since `Ints.checkedCast` returns the int value that is equal to non negative`long bits`,
   // Ints.checkedCast() can't return negative value
-          "value:argument.type.incompatible"// If long bits is in range from 0 to Integer.MAX_VALUE, LongMath.divide() return
-          //long value in range 0 to (Integer.MAX_VALUE / 64)
-          })
-
   static final class LockFreeBitArray {
     private static final int LONG_ADDRESSABLE_BITS = 6;
     final AtomicLongArray data;
@@ -259,29 +271,40 @@ void putAll(LockFreeBitArray other) {
           data.length(),
           other.data.length());
       for (int i = 0; i < data.length(); i++) {
-        long otherLong = other.data.get(i);
-
-        long ourLongOld;
-        long ourLongNew;
-        boolean changedAnyBits = true;
-        do {
-          ourLongOld = data.get(i);
-          ourLongNew = ourLongOld | otherLong;
-          if (ourLongOld == ourLongNew) {
-            changedAnyBits = false;
-            break;
-          }
-        } while (!data.compareAndSet(i, ourLongOld, ourLongNew));
+        putData(i, other.data.get(i));
+      }
+    }
 
-        if (changedAnyBits) {
-          int bitsAdded = Long.bitCount(ourLongNew) - Long.bitCount(ourLongOld);
-          bitCount.add(bitsAdded);
+    /**
+     * ORs the bits encoded in the {@code i}th {@code long} in the underlying {@link
+     * AtomicLongArray} with the given value.
+     */
+    void putData(int i, long longValue) {
+      long ourLongOld;
+      long ourLongNew;
+      boolean changedAnyBits = true;
+      do {
+        ourLongOld = data.get(i);
+        ourLongNew = ourLongOld | longValue;
+        if (ourLongOld == ourLongNew) {
+          changedAnyBits = false;
+          break;
         }
+      } while (!data.compareAndSet(i, ourLongOld, ourLongNew));
+
+      if (changedAnyBits) {
+        int bitsAdded = Long.bitCount(ourLongNew) - Long.bitCount(ourLongOld);
+        bitCount.add(bitsAdded);
       }
     }
 
+    /** Returns the number of {@code long}s in the underlying {@link AtomicLongArray}. */
+    int dataLength() {
+      return data.length();
+    }
+
     @Override
-    public boolean equals(@Nullable Object o) {
+    public boolean equals(@CheckForNull Object o) {
       if (o instanceof LockFreeBitArray) {
         LockFreeBitArray lockFreeBitArray = (LockFreeBitArray) o;
         // TODO(lowasser): avoid allocation here
diff --git a/guava/src/com/google/common/hash/ChecksumHashFunction.java b/guava/src/com/google/common/hash/ChecksumHashFunction.java
index 07802a10c0c1..e6e48002f4dc 100644
--- a/guava/src/com/google/common/hash/ChecksumHashFunction.java
+++ b/guava/src/com/google/common/hash/ChecksumHashFunction.java
@@ -31,6 +31,7 @@
  * @author Colin Decker
  */
 @Immutable
+@ElementTypesAreNonnullByDefault
 final class ChecksumHashFunction extends AbstractHashFunction implements Serializable {
   private final ImmutableSupplier<? extends Checksum> checksumSupplier;
   private final @NonNegative int bits;
diff --git a/guava/src/com/google/common/hash/Crc32cHashFunction.java b/guava/src/com/google/common/hash/Crc32cHashFunction.java
index 6837449cacff..ccda555823a3 100644
--- a/guava/src/com/google/common/hash/Crc32cHashFunction.java
+++ b/guava/src/com/google/common/hash/Crc32cHashFunction.java
@@ -25,6 +25,7 @@
  * @author Kurt Alfred Kluever
  */
 @Immutable
+@ElementTypesAreNonnullByDefault
 final class Crc32cHashFunction extends AbstractHashFunction {
   static final HashFunction CRC_32_C = new Crc32cHashFunction();
 
diff --git a/guava/src/com/google/common/hash/ElementTypesAreNonnullByDefault.java b/guava/src/com/google/common/hash/ElementTypesAreNonnullByDefault.java
new file mode 100644
index 000000000000..a2382b3514cc
--- /dev/null
+++ b/guava/src/com/google/common/hash/ElementTypesAreNonnullByDefault.java
@@ -0,0 +1,41 @@
+/*
+ * Copyright (C) 2021 The Guava Authors
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package com.google.common.hash;
+
+import static java.lang.annotation.ElementType.FIELD;
+import static java.lang.annotation.ElementType.METHOD;
+import static java.lang.annotation.ElementType.PARAMETER;
+import static java.lang.annotation.ElementType.TYPE;
+import static java.lang.annotation.RetentionPolicy.RUNTIME;
+
+import com.google.common.annotations.GwtCompatible;
+import java.lang.annotation.Retention;
+import java.lang.annotation.Target;
+import javax.annotation.Nonnull;
+import javax.annotation.meta.TypeQualifierDefault;
+
+/**
+ * Marks all "top-level" types as non-null in a way that is recognized by Kotlin. Note that this
+ * unfortunately includes type-variable usages, so we also provide {@link ParametricNullness} to
+ * "undo" it as best we can.
+ */
+@GwtCompatible
+@Retention(RUNTIME)
+@Target(TYPE)
+@TypeQualifierDefault({FIELD, METHOD, PARAMETER})
+@Nonnull
+@interface ElementTypesAreNonnullByDefault {}
diff --git a/guava/src/com/google/common/hash/FarmHashFingerprint64.java b/guava/src/com/google/common/hash/FarmHashFingerprint64.java
index c36f72c9bc61..25aa488b4dd6 100644
--- a/guava/src/com/google/common/hash/FarmHashFingerprint64.java
+++ b/guava/src/com/google/common/hash/FarmHashFingerprint64.java
@@ -44,6 +44,7 @@
  * @author Kyle Maddison
  * @author Geoff Pike
  */
+@ElementTypesAreNonnullByDefault
 final class FarmHashFingerprint64 extends AbstractNonStreamingHashFunction {
   static final HashFunction FARMHASH_FINGERPRINT_64 = new FarmHashFingerprint64();
 
@@ -176,7 +177,7 @@ private static long hashLength33To64(byte[] bytes, @NonNegative  @LTLengthOf(val
    * Compute an 8-byte hash of a byte array of length greater than 64 bytes.
    */
   private static long hashLength65Plus(byte[] bytes, @NonNegative @LTLengthOf(value = "#1", offset = "#3 - 1") int offset, @IntRange(from = 65) @LTLengthOf(value = "#1", offset = "#2 - 1") int length) {
-    final int seed = 81;
+    int seed = 81;
     // For strings over 64 bytes we loop. Internal state consists of 56 bytes: v, w, x, y, and z.
     long x = seed;
     @SuppressWarnings("ConstantOverflow")
diff --git a/guava/src/com/google/common/hash/Fingerprint2011.java b/guava/src/com/google/common/hash/Fingerprint2011.java
new file mode 100644
index 000000000000..1b01e0092418
--- /dev/null
+++ b/guava/src/com/google/common/hash/Fingerprint2011.java
@@ -0,0 +1,198 @@
+// Copyright 2011 Google Inc. All Rights Reserved.
+
+package com.google.common.hash;
+
+import static com.google.common.base.Preconditions.checkPositionIndexes;
+import static com.google.common.hash.LittleEndianByteArray.load64;
+import static com.google.common.hash.LittleEndianByteArray.load64Safely;
+import static java.lang.Long.rotateRight;
+
+import com.google.common.annotations.VisibleForTesting;
+
+/**
+ * Implementation of Geoff Pike's fingerprint2011 hash function. See {@link Hashing#fingerprint2011}
+ * for information on the behaviour of the algorithm.
+ *
+ * <p>On Intel Core2 2.66, on 1000 bytes, fingerprint2011 takes 0.9 microseconds compared to
+ * fingerprint at 4.0 microseconds and md5 at 4.5 microseconds.
+ *
+ * <p>Note to maintainers: This implementation relies on signed arithmetic being bit-wise equivalent
+ * to unsigned arithmetic in all cases except:
+ *
+ * <ul>
+ *   <li>comparisons (signed values can be negative)
+ *   <li>division (avoided here)
+ *   <li>shifting (right shift must be unsigned)
+ * </ul>
+ *
+ * @author kylemaddison@google.com (Kyle Maddison)
+ * @author gpike@google.com (Geoff Pike)
+ */
+@ElementTypesAreNonnullByDefault
+final class Fingerprint2011 extends AbstractNonStreamingHashFunction {
+  static final HashFunction FINGERPRINT_2011 = new Fingerprint2011();
+
+  // Some primes between 2^63 and 2^64 for various uses.
+  private static final long K0 = 0xa5b85c5e198ed849L;
+  private static final long K1 = 0x8d58ac26afe12e47L;
+  private static final long K2 = 0xc47b6e9e3a970ed3L;
+  private static final long K3 = 0xc6a4a7935bd1e995L;
+
+  @Override
+  public HashCode hashBytes(byte[] input, int off, int len) {
+    checkPositionIndexes(off, off + len, input.length);
+    return HashCode.fromLong(fingerprint(input, off, len));
+  }
+
+  @Override
+  public int bits() {
+    return 64;
+  }
+
+  @Override
+  public String toString() {
+    return "Hashing.fingerprint2011()";
+  }
+
+  // End of public functions.
+
+  @VisibleForTesting
+  static long fingerprint(byte[] bytes, int offset, int length) {
+    long result;
+
+    if (length <= 32) {
+      result = murmurHash64WithSeed(bytes, offset, length, K0 ^ K1 ^ K2);
+    } else if (length <= 64) {
+      result = hashLength33To64(bytes, offset, length);
+    } else {
+      result = fullFingerprint(bytes, offset, length);
+    }
+
+    long u = length >= 8 ? load64(bytes, offset) : K0;
+    long v = length >= 9 ? load64(bytes, offset + length - 8) : K0;
+    result = hash128to64(result + v, u);
+    return result == 0 || result == 1 ? result + ~1 : result;
+  }
+
+  private static long shiftMix(long val) {
+    return val ^ (val >>> 47);
+  }
+
+  /** Implementation of Hash128to64 from util/hash/hash128to64.h */
+  @VisibleForTesting
+  static long hash128to64(long high, long low) {
+    long a = (low ^ high) * K3;
+    a ^= (a >>> 47);
+    long b = (high ^ a) * K3;
+    b ^= (b >>> 47);
+    b *= K3;
+    return b;
+  }
+
+  /**
+   * Computes intermediate hash of 32 bytes of byte array from the given offset. Results are
+   * returned in the output array - this is 12% faster than allocating new arrays every time.
+   */
+  private static void weakHashLength32WithSeeds(
+      byte[] bytes, int offset, long seedA, long seedB, long[] output) {
+    long part1 = load64(bytes, offset);
+    long part2 = load64(bytes, offset + 8);
+    long part3 = load64(bytes, offset + 16);
+    long part4 = load64(bytes, offset + 24);
+
+    seedA += part1;
+    seedB = rotateRight(seedB + seedA + part4, 51);
+    long c = seedA;
+    seedA += part2;
+    seedA += part3;
+    seedB += rotateRight(seedA, 23);
+    output[0] = seedA + part4;
+    output[1] = seedB + c;
+  }
+
+  /*
+   * Compute an 8-byte hash of a byte array of length greater than 64 bytes.
+   */
+  private static long fullFingerprint(byte[] bytes, int offset, int length) {
+    // For lengths over 64 bytes we hash the end first, and then as we
+    // loop we keep 56 bytes of state: v, w, x, y, and z.
+    long x = load64(bytes, offset);
+    long y = load64(bytes, offset + length - 16) ^ K1;
+    long z = load64(bytes, offset + length - 56) ^ K0;
+    long[] v = new long[2];
+    long[] w = new long[2];
+    weakHashLength32WithSeeds(bytes, offset + length - 64, length, y, v);
+    weakHashLength32WithSeeds(bytes, offset + length - 32, length * K1, K0, w);
+    z += shiftMix(v[1]) * K1;
+    x = rotateRight(z + x, 39) * K1;
+    y = rotateRight(y, 33) * K1;
+
+    // Decrease length to the nearest multiple of 64, and operate on 64-byte chunks.
+    length = (length - 1) & ~63;
+    do {
+      x = rotateRight(x + y + v[0] + load64(bytes, offset + 16), 37) * K1;
+      y = rotateRight(y + v[1] + load64(bytes, offset + 48), 42) * K1;
+      x ^= w[1];
+      y ^= v[0];
+      z = rotateRight(z ^ w[0], 33);
+      weakHashLength32WithSeeds(bytes, offset, v[1] * K1, x + w[0], v);
+      weakHashLength32WithSeeds(bytes, offset + 32, z + w[1], y, w);
+      long tmp = z;
+      z = x;
+      x = tmp;
+      offset += 64;
+      length -= 64;
+    } while (length != 0);
+    return hash128to64(hash128to64(v[0], w[0]) + shiftMix(y) * K1 + z, hash128to64(v[1], w[1]) + x);
+  }
+
+  private static long hashLength33To64(byte[] bytes, int offset, int length) {
+    long z = load64(bytes, offset + 24);
+    long a = load64(bytes, offset) + (length + load64(bytes, offset + length - 16)) * K0;
+    long b = rotateRight(a + z, 52);
+    long c = rotateRight(a, 37);
+    a += load64(bytes, offset + 8);
+    c += rotateRight(a, 7);
+    a += load64(bytes, offset + 16);
+    long vf = a + z;
+    long vs = b + rotateRight(a, 31) + c;
+    a = load64(bytes, offset + 16) + load64(bytes, offset + length - 32);
+    z = load64(bytes, offset + length - 8);
+    b = rotateRight(a + z, 52);
+    c = rotateRight(a, 37);
+    a += load64(bytes, offset + length - 24);
+    c += rotateRight(a, 7);
+    a += load64(bytes, offset + length - 16);
+    long wf = a + z;
+    long ws = b + rotateRight(a, 31) + c;
+    long r = shiftMix((vf + ws) * K2 + (wf + vs) * K0);
+    return shiftMix(r * K0 + vs) * K2;
+  }
+
+  @VisibleForTesting
+  static long murmurHash64WithSeed(byte[] bytes, int offset, int length, long seed) {
+    long mul = K3;
+    int topBit = 0x7;
+
+    int lengthAligned = length & ~topBit;
+    int lengthRemainder = length & topBit;
+    long hash = seed ^ (length * mul);
+
+    for (int i = 0; i < lengthAligned; i += 8) {
+      long loaded = load64(bytes, offset + i);
+      long data = shiftMix(loaded * mul) * mul;
+      hash ^= data;
+      hash *= mul;
+    }
+
+    if (lengthRemainder != 0) {
+      long data = load64Safely(bytes, offset + lengthAligned, lengthRemainder);
+      hash ^= data;
+      hash *= mul;
+    }
+
+    hash = shiftMix(hash) * mul;
+    hash = shiftMix(hash);
+    return hash;
+  }
+}
diff --git a/guava/src/com/google/common/hash/Funnel.java b/guava/src/com/google/common/hash/Funnel.java
index 2c6a7b9820f5..9d80dabcf6ed 100644
--- a/guava/src/com/google/common/hash/Funnel.java
+++ b/guava/src/com/google/common/hash/Funnel.java
@@ -17,6 +17,7 @@
 import com.google.common.annotations.Beta;
 import com.google.errorprone.annotations.DoNotMock;
 import java.io.Serializable;
+import org.checkerframework.checker.nullness.qual.Nullable;
 
 /**
  * An object which can send data from an object of type {@code T} into a {@code PrimitiveSink}.
@@ -43,7 +44,8 @@
  */
 @Beta
 @DoNotMock("Implement with a lambda")
-public interface Funnel<T> extends Serializable {
+@ElementTypesAreNonnullByDefault
+public interface Funnel<T extends @Nullable Object> extends Serializable {
 
   /**
    * Sends a stream of data from the {@code from} object into the sink {@code into}. There is no
@@ -51,5 +53,5 @@ public interface Funnel<T> extends Serializable {
    *
    * @since 12.0 (in Guava 11.0, {@code PrimitiveSink} was named {@code Sink})
    */
-  void funnel(T from, PrimitiveSink into);
+  void funnel(@ParametricNullness T from, PrimitiveSink into);
 }
diff --git a/guava/src/com/google/common/hash/Funnels.java b/guava/src/com/google/common/hash/Funnels.java
index 75691d8ebbc3..e7020f1ebf0c 100644
--- a/guava/src/com/google/common/hash/Funnels.java
+++ b/guava/src/com/google/common/hash/Funnels.java
@@ -19,6 +19,7 @@
 import java.io.OutputStream;
 import java.io.Serializable;
 import java.nio.charset.Charset;
+import javax.annotation.CheckForNull;
 import org.checkerframework.checker.index.qual.LTLengthOf;
 import org.checkerframework.checker.index.qual.NonNegative;
 import org.checkerframework.checker.nullness.qual.Nullable;
@@ -32,6 +33,7 @@
  * @since 11.0
  */
 @Beta
+@ElementTypesAreNonnullByDefault
 public final class Funnels {
   private Funnels() {}
 
@@ -44,6 +46,7 @@ private enum ByteArrayFunnel implements Funnel<byte[]> {
     INSTANCE;
 
     @Override
+    @SuppressWarnings("value:argument") // 'from' should be annotated @MinLen(1)
     public void funnel(byte [] from, PrimitiveSink into) {
       into.putBytes(from);
     }
@@ -97,6 +100,7 @@ private static class StringCharsetFunnel implements Funnel<CharSequence>, Serial
     }
 
     @Override
+    @SuppressWarnings("value:argument") // 'from' should be annotated @MinLen(1)
     public void funnel(CharSequence from, PrimitiveSink into) {
       into.putString(from, charset);
     }
@@ -107,7 +111,7 @@ public String toString() {
     }
 
     @Override
-    public boolean equals(@Nullable Object o) {
+    public boolean equals(@CheckForNull Object o) {
       if (o instanceof StringCharsetFunnel) {
         StringCharsetFunnel funnel = (StringCharsetFunnel) o;
         return this.charset.equals(funnel.charset);
@@ -168,11 +172,13 @@ public String toString() {
    *
    * @since 15.0
    */
-  public static <E> Funnel<Iterable<? extends E>> sequentialFunnel(Funnel<E> elementFunnel) {
-    return new SequentialFunnel<E>(elementFunnel);
+  public static <E extends @Nullable Object> Funnel<Iterable<? extends E>> sequentialFunnel(
+      Funnel<E> elementFunnel) {
+    return new SequentialFunnel<>(elementFunnel);
   }
 
-  private static class SequentialFunnel<E> implements Funnel<Iterable<? extends E>>, Serializable {
+  private static class SequentialFunnel<E extends @Nullable Object>
+      implements Funnel<Iterable<? extends E>>, Serializable {
     private final Funnel<E> elementFunnel;
 
     SequentialFunnel(Funnel<E> elementFunnel) {
@@ -192,7 +198,7 @@ public String toString() {
     }
 
     @Override
-    public boolean equals(@Nullable Object o) {
+    public boolean equals(@CheckForNull Object o) {
       if (o instanceof SequentialFunnel) {
         SequentialFunnel<?> funnel = (SequentialFunnel<?>) o;
         return elementFunnel.equals(funnel.elementFunnel);
diff --git a/guava/src/com/google/common/hash/HashCode.java b/guava/src/com/google/common/hash/HashCode.java
index c968589957f3..1e9b85a23e3f 100644
--- a/guava/src/com/google/common/hash/HashCode.java
+++ b/guava/src/com/google/common/hash/HashCode.java
@@ -23,6 +23,7 @@
 import com.google.common.primitives.UnsignedInts;
 import com.google.errorprone.annotations.CanIgnoreReturnValue;
 import java.io.Serializable;
+import javax.annotation.CheckForNull;
 import org.checkerframework.checker.index.qual.LTLengthOf;
 import org.checkerframework.checker.index.qual.LengthOf;
 import org.checkerframework.checker.index.qual.NonNegative;
@@ -39,6 +40,7 @@
  * @author Kurt Alfred Kluever
  * @since 11.0
  */
+@ElementTypesAreNonnullByDefault
 public abstract class HashCode {
   HashCode() {}
 
@@ -87,9 +89,9 @@ public abstract class HashCode {
    * @return the number of bytes written to {@code dest}
    * @throws IndexOutOfBoundsException if there is not enough room in {@code dest}
    */
-  @SuppressWarnings({"lowerbound:assignment.type.incompatible",// Since bits() return non negative value, `bits() / 8`
+  @SuppressWarnings({"lowerbound:assignment",// Since bits() return non negative value, `bits() / 8`
           //return non negative.
-          "upperbound:assignment.type.incompatible"//(1) maxLength is = `bits() / 8` if maxLength < bits() / 8.
+          "upperbound:assignment"//(1) maxLength is = `bits() / 8` if maxLength < bits() / 8.
           //Since bits() returns a positive multiple of 8, `bits() / 8 + offset - 1` < dest.length
           })
   @CanIgnoreReturnValue
@@ -300,6 +302,7 @@ public long asLong() {
     }
 
     @Override
+    @SuppressWarnings("upperbound:array.access.unsafe.high.range")
     public long padToLong() {
       long retVal = (bytes[0] & 0xFF);
       for (int i = 1; i < Math.min(bytes.length, 8); i++) {
@@ -309,6 +312,7 @@ public long padToLong() {
     }
 
     @Override
+    @SuppressWarnings("upperbound:argument")
     void writeBytesToImpl(byte[] dest, @NonNegative @LTLengthOf(value = "#1", offset = "#3 - 1") int offset, @NonNegative @LTLengthOf(value = "#1", offset = "#2 - 1") int maxLength) {
       System.arraycopy(bytes, 0, dest, offset, maxLength);
     }
@@ -319,8 +323,6 @@ void writeBytesToImpl(byte[] dest, @NonNegative @LTLengthOf(value = "#1", offset
     }
 
     @Override
-    @SuppressWarnings("upperbound:array.access.unsafe.high")/* Since `this.bytes.length` has same length as that.getBytesInternal().length
-    ( else return false), `i` range from 0 to `this.bytes.length` is safe as indexes.*/
     boolean equalsSameBits(HashCode that) {
       // We don't use MessageDigest.isEqual() here because its contract does not guarantee
       // constant-time evaluation (no short-circuiting).
@@ -348,7 +350,11 @@ boolean equalsSameBits(HashCode that) {
    *
    * @since 15.0
    */
-  @SuppressWarnings("value:argument") // fromBytesNoCopy verfies bytes contains at least 1 byte
+  @SuppressWarnings({
+      "value:argument", // fromBytesNoCopy verfies bytes contains at least 1 byte
+      "index:argument", // charAt
+      "upperbound:array.access.unsafe.high",
+  })
   public static HashCode fromString(String string) {
     checkArgument(
         string.length() >= 2, "input string (%s) must have at least 2 characters", string);
@@ -383,7 +389,7 @@ private static int decode(char ch) {
    * to protect against <a href="http://en.wikipedia.org/wiki/Timing_attack">timing attacks</a>.
    */
   @Override
-  public final boolean equals(@Nullable Object object) {
+  public final boolean equals(@CheckForNull Object object) {
     if (object instanceof HashCode) {
       HashCode that = (HashCode) object;
       return bits() == that.bits() && equalsSameBits(that);
diff --git a/guava/src/com/google/common/hash/HashFunction.java b/guava/src/com/google/common/hash/HashFunction.java
index 2fe1794b0854..a9f72c18a219 100644
--- a/guava/src/com/google/common/hash/HashFunction.java
+++ b/guava/src/com/google/common/hash/HashFunction.java
@@ -14,7 +14,6 @@
 
 package com.google.common.hash;
 
-import com.google.common.annotations.Beta;
 import com.google.common.primitives.Ints;
 import com.google.errorprone.annotations.Immutable;
 import org.checkerframework.checker.index.qual.LTLengthOf;
@@ -22,6 +21,7 @@
 import org.checkerframework.common.value.qual.MinLen;
 import java.nio.ByteBuffer;
 import java.nio.charset.Charset;
+import org.checkerframework.checker.nullness.qual.Nullable;
 
 /**
  * A hash function is a collision-averse pure function that maps an arbitrary block of data to a
@@ -118,8 +118,8 @@
  * @author Kevin Bourrillion
  * @since 11.0
  */
-@Beta
 @Immutable
+@ElementTypesAreNonnullByDefault
 public interface HashFunction {
   /**
    * Begins a new hash code computation by returning an initialized, stateful {@code Hasher}
@@ -214,7 +214,8 @@ public interface HashFunction {
    *
    * @since 14.0
    */
-  <T> HashCode hashObject(T instance, Funnel<? super T> funnel);
+  <T extends @Nullable Object> HashCode hashObject(
+      @ParametricNullness T instance, Funnel<? super T> funnel);
 
   /**
    * Returns the number of bits (a multiple of 32) that each hash code produced by this hash
diff --git a/guava/src/com/google/common/hash/Hasher.java b/guava/src/com/google/common/hash/Hasher.java
index 69b749ab1f94..91674eb2b0d6 100644
--- a/guava/src/com/google/common/hash/Hasher.java
+++ b/guava/src/com/google/common/hash/Hasher.java
@@ -21,6 +21,7 @@
 import org.checkerframework.common.value.qual.MinLen;
 import java.nio.ByteBuffer;
 import java.nio.charset.Charset;
+import org.checkerframework.checker.nullness.qual.Nullable;
 
 /**
  * A {@link PrimitiveSink} that can compute a hash code after reading the input. Each hasher should
@@ -57,6 +58,7 @@
  */
 @Beta
 @CanIgnoreReturnValue
+@ElementTypesAreNonnullByDefault
 public interface Hasher extends PrimitiveSink {
   @Override
   Hasher putByte(byte b);
@@ -122,7 +124,8 @@ public interface Hasher extends PrimitiveSink {
   Hasher putString(@MinLen(1) CharSequence charSequence, Charset charset);
 
   /** A simple convenience for {@code funnel.funnel(object, this)}. */
-  <T> Hasher putObject(T instance, Funnel<? super T> funnel);
+  <T extends @Nullable Object> Hasher putObject(
+      @ParametricNullness T instance, Funnel<? super T> funnel);
 
   /**
    * Computes a hash code based on the data that have been provided to this hasher. The result is
diff --git a/guava/src/com/google/common/hash/Hashing.java b/guava/src/com/google/common/hash/Hashing.java
index 36dc19a784b1..de6f309c5f41 100644
--- a/guava/src/com/google/common/hash/Hashing.java
+++ b/guava/src/com/google/common/hash/Hashing.java
@@ -17,16 +17,17 @@
 import static com.google.common.base.Preconditions.checkArgument;
 import static com.google.common.base.Preconditions.checkNotNull;
 
-import com.google.common.annotations.Beta;
 import com.google.errorprone.annotations.Immutable;
 import java.security.Key;
 import java.util.ArrayList;
 import java.util.Arrays;
+import java.util.Collections;
 import java.util.Iterator;
 import java.util.List;
 import java.util.zip.Adler32;
 import java.util.zip.CRC32;
 import java.util.zip.Checksum;
+import javax.annotation.CheckForNull;
 import javax.crypto.spec.SecretKeySpec;
 import org.checkerframework.checker.index.qual.NonNegative;
 import org.checkerframework.checker.index.qual.Positive;
@@ -46,7 +47,7 @@
  * @author Kurt Alfred Kluever
  * @since 11.0
  */
-@Beta
+@ElementTypesAreNonnullByDefault
 public final class Hashing {
   /**
    * Returns a general-purpose, <b>temporary-use</b>, non-cryptographic hash function. The algorithm
@@ -94,15 +95,56 @@ public static HashFunction goodFastHash(@Positive int minimumBits) {
   @SuppressWarnings("GoodTime") // reading system time without TimeSource
   static final int GOOD_FAST_HASH_SEED = (int) System.currentTimeMillis();
 
+  /**
+   * Returns a hash function implementing the <a
+   * href="https://github.com/aappleby/smhasher/blob/master/src/MurmurHash3.cpp">32-bit murmur3
+   * algorithm, x86 variant</a> (little-endian variant), using the given seed value, <b>with a known
+   * bug</b> as described in the deprecation text.
+   *
+   * <p>The C++ equivalent is the MurmurHash3_x86_32 function (Murmur3A), which however does not
+   * have the bug.
+   *
+   * @deprecated This implementation produces incorrect hash values from the {@link
+   *     HashFunction#hashString} method if the string contains non-BMP characters. Use {@link
+   *     #murmur3_32_fixed(int)} instead.
+   */
+  @Deprecated
+  public static HashFunction murmur3_32(int seed) {
+    return new Murmur3_32HashFunction(seed, /* supplementaryPlaneFix= */ false);
+  }
+
+  /**
+   * Returns a hash function implementing the <a
+   * href="https://github.com/aappleby/smhasher/blob/master/src/MurmurHash3.cpp">32-bit murmur3
+   * algorithm, x86 variant</a> (little-endian variant), using the given seed value, <b>with a known
+   * bug</b> as described in the deprecation text.
+   *
+   * <p>The C++ equivalent is the MurmurHash3_x86_32 function (Murmur3A), which however does not
+   * have the bug.
+   *
+   * @deprecated This implementation produces incorrect hash values from the {@link
+   *     HashFunction#hashString} method if the string contains non-BMP characters. Use {@link
+   *     #murmur3_32_fixed()} instead.
+   */
+  @Deprecated
+  public static HashFunction murmur3_32() {
+    return Murmur3_32HashFunction.MURMUR3_32;
+  }
+
   /**
    * Returns a hash function implementing the <a
    * href="https://github.com/aappleby/smhasher/blob/master/src/MurmurHash3.cpp">32-bit murmur3
    * algorithm, x86 variant</a> (little-endian variant), using the given seed value.
    *
    * <p>The exact C++ equivalent is the MurmurHash3_x86_32 function (Murmur3A).
+   *
+   * <p>This method is called {@code murmur3_32_fixed} because it fixes a bug in the {@code
+   * HashFunction} returned by the original {@code murmur3_32} method.
+   *
+   * @since 31.0
    */
-  public static HashFunction murmur3_32(int seed) {
-    return new Murmur3_32HashFunction(seed);
+  public static HashFunction murmur3_32_fixed(int seed) {
+    return new Murmur3_32HashFunction(seed, /* supplementaryPlaneFix= */ true);
   }
 
   /**
@@ -111,9 +153,14 @@ public static HashFunction murmur3_32(int seed) {
    * algorithm, x86 variant</a> (little-endian variant), using a seed value of zero.
    *
    * <p>The exact C++ equivalent is the MurmurHash3_x86_32 function (Murmur3A).
+   *
+   * <p>This method is called {@code murmur3_32_fixed} because it fixes a bug in the {@code
+   * HashFunction} returned by the original {@code murmur3_32} method.
+   *
+   * @since 31.0
    */
-  public static HashFunction murmur3_32() {
-    return Murmur3_32HashFunction.MURMUR3_32;
+  public static HashFunction murmur3_32_fixed() {
+    return Murmur3_32HashFunction.MURMUR3_32_FIXED;
   }
 
   /**
@@ -426,6 +473,30 @@ public static HashFunction farmHashFingerprint64() {
     return FarmHashFingerprint64.FARMHASH_FINGERPRINT_64;
   }
 
+  /**
+   * Returns a hash function implementing the Fingerprint2011 hashing function (64 hash bits).
+   *
+   * <p>This is designed for generating persistent fingerprints of strings. It isn't
+   * cryptographically secure, but it produces a high-quality hash with few collisions. Fingerprints
+   * generated using this are byte-wise identical to those created using the C++ version, but note
+   * that this uses unsigned integers (see {@link com.google.common.primitives.UnsignedInts}).
+   * Comparisons between the two should take this into account.
+   *
+   * <p>Fingerprint2011() is a form of Murmur2 on strings up to 32 bytes and a form of CityHash for
+   * longer strings. It could have been one or the other throughout. The main advantage of the
+   * combination is that CityHash has a bunch of special cases for short strings that don't need to
+   * be replicated here. The result will never be 0 or 1.
+   *
+   * <p>This function is best understood as a <a
+   * href="https://en.wikipedia.org/wiki/Fingerprint_(computing)">fingerprint</a> rather than a true
+   * <a href="https://en.wikipedia.org/wiki/Hash_function">hash function</a>.
+   *
+   * @since 31.1
+   */
+  public static HashFunction fingerprint2011() {
+    return Fingerprint2011.FINGERPRINT_2011;
+  }
+
   /**
    * Assigns to {@code hashCode} a "bucket" in the range {@code [0, buckets)}, in a uniform manner
    * that minimizes the need for remapping as {@code buckets} grows. That is, {@code
@@ -583,7 +654,7 @@ public static HashFunction concatenating(
     List<HashFunction> list = new ArrayList<>();
     list.add(first);
     list.add(second);
-    list.addAll(Arrays.asList(rest));
+    Collections.addAll(list, rest);
     return new ConcatenatedHashFunction(list.toArray(new HashFunction[0]));
   }
 
@@ -604,7 +675,7 @@ public static HashFunction concatenating(Iterable<HashFunction> hashFunctions) {
     for (HashFunction hashFunction : hashFunctions) {
       list.add(hashFunction);
     }
-    checkArgument(list.size() > 0, "number of hash functions (%s) must be > 0", list.size());
+    checkArgument(!list.isEmpty(), "number of hash functions (%s) must be > 0", list.size());
     return new ConcatenatedHashFunction(list.toArray(new HashFunction[0]));
   }
 
@@ -643,7 +714,7 @@ HashCode makeHash(Hasher[] hashers) {
     }
 
     @Override
-    public boolean equals(@Nullable Object object) {
+    public boolean equals(@CheckForNull Object object) {
       if (object instanceof ConcatenatedHashFunction) {
         ConcatenatedHashFunction other = (ConcatenatedHashFunction) object;
         return Arrays.equals(functions, other.functions);
diff --git a/guava/src/com/google/common/hash/HashingInputStream.java b/guava/src/com/google/common/hash/HashingInputStream.java
index ce2e874754da..c4fe7737b25e 100644
--- a/guava/src/com/google/common/hash/HashingInputStream.java
+++ b/guava/src/com/google/common/hash/HashingInputStream.java
@@ -31,6 +31,7 @@
  * @since 16.0
  */
 @Beta
+@ElementTypesAreNonnullByDefault
 public final class HashingInputStream extends FilterInputStream {
   private final Hasher hasher;
 
@@ -51,6 +52,7 @@ public HashingInputStream(HashFunction hashFunction, InputStream in) {
    */
   @Override
   @CanIgnoreReturnValue
+  @SuppressWarnings("index:override.return")
   public int read() throws IOException {
     int b = in.read();
     if (b != -1) {
@@ -65,11 +67,11 @@ public int read() throws IOException {
    */
   @Override
   @CanIgnoreReturnValue
-  @SuppressWarnings({"override.param.invalid",//FilterInputStream#read should be annotated as
-          // @NonNegative @LTLengthOf(value = "#1",offset = "#2 - 1") int read()
-          "upperbound:argument.type.incompatible",//(1): param `off` should be annotated as @LTLengthOf(value = "#1",offset = "numOfBytesRead - 1")
-          //However, numOfBytesRead is declared inside method body.
-          "lowerbound:assignment.type.incompatible"//(2): Input#stream() should be annotated as `@NonNegative int read()`
+  @SuppressWarnings({"index:override.return", // FilterInputStream#read should be annotated as
+      // @NonNegative @LTLengthOf(value = "#1",offset = "#2 - 1") int read()
+      "upperbound:argument", // (1): param `off` should be annotated as @LTLengthOf(value = "#1",offset = "numOfBytesRead - 1")
+      // However, numOfBytesRead is declared inside method body.
+      "lowerbound:assignment" // (2): Input#stream() should be annotated as `@NonNegative int read()`
   })
   public int read(byte[] bytes, @NonNegative int off, @NonNegative int len) throws IOException {
     @NonNegative int numOfBytesRead = in.read(bytes, off, len);//(2)
diff --git a/guava/src/com/google/common/hash/HashingOutputStream.java b/guava/src/com/google/common/hash/HashingOutputStream.java
index 1f9b372d76e6..a96f9e2e991b 100644
--- a/guava/src/com/google/common/hash/HashingOutputStream.java
+++ b/guava/src/com/google/common/hash/HashingOutputStream.java
@@ -30,6 +30,7 @@
  * @since 16.0
  */
 @Beta
+@ElementTypesAreNonnullByDefault
 public final class HashingOutputStream extends FilterOutputStream {
   private final Hasher hasher;
 
diff --git a/guava/src/com/google/common/hash/ImmutableSupplier.java b/guava/src/com/google/common/hash/ImmutableSupplier.java
index f90352afca75..24f711a313fa 100644
--- a/guava/src/com/google/common/hash/ImmutableSupplier.java
+++ b/guava/src/com/google/common/hash/ImmutableSupplier.java
@@ -21,5 +21,7 @@
  * Explicitly named subinterface of {@link Supplier} that can be marked {@literal @}{@link
  * Immutable}.
  */
+// TODO(cpovirk): Should we just use ChecksumType directly instead of defining this type?
 @Immutable
+@ElementTypesAreNonnullByDefault
 interface ImmutableSupplier<T> extends Supplier<T> {}
diff --git a/guava/src/com/google/common/hash/Java8Compatibility.java b/guava/src/com/google/common/hash/Java8Compatibility.java
index 52f71e788558..c15f2b3cc575 100644
--- a/guava/src/com/google/common/hash/Java8Compatibility.java
+++ b/guava/src/com/google/common/hash/Java8Compatibility.java
@@ -22,6 +22,7 @@
  * https://github.com/google/guava/issues/3990
  */
 @GwtIncompatible
+@ElementTypesAreNonnullByDefault
 final class Java8Compatibility {
   static void clear(Buffer b) {
     b.clear();
diff --git a/guava/src/com/google/common/hash/LittleEndianByteArray.java b/guava/src/com/google/common/hash/LittleEndianByteArray.java
index 05f6619065eb..a93a76ff63d9 100644
--- a/guava/src/com/google/common/hash/LittleEndianByteArray.java
+++ b/guava/src/com/google/common/hash/LittleEndianByteArray.java
@@ -26,6 +26,7 @@
  * @author Kevin Damm
  * @author Kyle Maddison
  */
+@ElementTypesAreNonnullByDefault
 final class LittleEndianByteArray {
 
   /** The instance that actually does the work; delegates to Unsafe or a pure-Java fallback. */
@@ -39,7 +40,7 @@ final class LittleEndianByteArray {
    * @param offset the offset into the array at which to start
    * @return a long of a concatenated 8 bytes
    */
-  @SuppressWarnings("upperbound:argument.type.incompatible")// method uses assertion
+  @SuppressWarnings("upperbound:argument") // method uses assertion
   // to ensure `offset + 8` <= input.length, same as `offset + 8 - 1 < input.length`
   static long load64(byte[] input, @NonNegative int offset) {
     // We don't want this in production code as this is the most critical part of the loop.
@@ -58,6 +59,7 @@ static long load64(byte[] input, @NonNegative int offset) {
    * @param length the number of bytes from the input to read
    * @return a long of a concatenated 8 bytes
    */
+  @SuppressWarnings("upperbound:array.access.unsafe.high")
   static long load64Safely(byte[] input, @NonNegative @LTLengthOf(value = "#1",offset = "#3") int offset, @NonNegative @LTLengthOf(value = "#1",offset = "#2") int length) {
     long result = 0;
     // Due to the way we shift, we can stop iterating once we've run out of data, the rest
@@ -247,7 +249,7 @@ public void putLongLittleEndian(byte[] sink, @NonNegative @LTLengthOf(value = "#
        * which will have an efficient native implementation in JDK 9.
        *
        */
-      final String arch = System.getProperty("os.arch");
+      String arch = System.getProperty("os.arch");
       if ("amd64".equals(arch)) {
         theGetter =
             ByteOrder.nativeOrder().equals(ByteOrder.LITTLE_ENDIAN)
diff --git a/guava/src/com/google/common/hash/LongAddable.java b/guava/src/com/google/common/hash/LongAddable.java
index a95eece2e1ff..5c6a7f0c7db8 100644
--- a/guava/src/com/google/common/hash/LongAddable.java
+++ b/guava/src/com/google/common/hash/LongAddable.java
@@ -14,11 +14,13 @@
 
 package com.google.common.hash;
 
+
 /**
  * Abstract interface for objects that can concurrently add longs.
  *
  * @author Louis Wasserman
  */
+@ElementTypesAreNonnullByDefault
 interface LongAddable {
   void increment();
 
diff --git a/guava/src/com/google/common/hash/LongAddables.java b/guava/src/com/google/common/hash/LongAddables.java
index d2768bcf5c42..7c371ec88fdc 100644
--- a/guava/src/com/google/common/hash/LongAddables.java
+++ b/guava/src/com/google/common/hash/LongAddables.java
@@ -22,13 +22,15 @@
  *
  * @author Louis Wasserman
  */
+@ElementTypesAreNonnullByDefault
 final class LongAddables {
   private static final Supplier<LongAddable> SUPPLIER;
 
   static {
     Supplier<LongAddable> supplier;
     try {
-      new LongAdder(); // trigger static initialization of the LongAdder class, which may fail
+      // trigger static initialization of the LongAdder class, which may fail
+      LongAdder unused = new LongAdder();
       supplier =
           new Supplier<LongAddable>() {
             @Override
diff --git a/guava/src/com/google/common/hash/LongAdder.java b/guava/src/com/google/common/hash/LongAdder.java
index e47b7366694a..0eaaf7ec7875 100644
--- a/guava/src/com/google/common/hash/LongAdder.java
+++ b/guava/src/com/google/common/hash/LongAdder.java
@@ -40,6 +40,7 @@
  * @since 1.8
  * @author Doug Lea
  */
+@ElementTypesAreNonnullByDefault
 final class LongAdder extends Striped64 implements Serializable, LongAddable {
   private static final long serialVersionUID = 7249069246863182397L;
 
diff --git a/guava/src/com/google/common/hash/MacHashFunction.java b/guava/src/com/google/common/hash/MacHashFunction.java
index c1eefa6eb8ee..20da33532d12 100644
--- a/guava/src/com/google/common/hash/MacHashFunction.java
+++ b/guava/src/com/google/common/hash/MacHashFunction.java
@@ -31,6 +31,7 @@
  * @author Kurt Alfred Kluever
  */
 @Immutable
+@ElementTypesAreNonnullByDefault
 final class MacHashFunction extends AbstractHashFunction {
 
   @SuppressWarnings("Immutable") // cloned before each use
@@ -43,7 +44,7 @@ final class MacHashFunction extends AbstractHashFunction {
   private final @NonNegative int bits;
   private final boolean supportsClone;
 
-  @SuppressWarnings("lowerbound:assignment.type.incompatible")/*(1): method `engineGetMacLength()` in the pre-compiled class `MacSpi`
+  @SuppressWarnings("lowerbound:assignment") /* (1): method `engineGetMacLength()` in the pre-compiled class `MacSpi`
   should be annotated to return @NonNegative value */
   MacHashFunction(String algorithmName, Key key, String toString) {
     this.prototype = getMac(algorithmName, key);
@@ -60,7 +61,7 @@ final class MacHashFunction extends AbstractHashFunction {
 
   private static boolean supportsClone(Mac mac) {
     try {
-      mac.clone();
+      Object unused = mac.clone();
       return true;
     } catch (CloneNotSupportedException e) {
       return false;
@@ -134,8 +135,8 @@ private void checkNotDone() {
       checkState(!done, "Cannot re-use a Hasher after calling hash() on it");
     }
 
-    @SuppressWarnings("value:argument.type.incompatible")// Max#doFinal() should be annotated as @MinLen(1) doFinal()
     @Override
+    @SuppressWarnings("value:argument") // Max#doFinal() should be annotated as @MinLen(1) doFinal()
     public HashCode hash() {
       checkNotDone();
       done = true;
diff --git a/guava/src/com/google/common/hash/MessageDigestHashFunction.java b/guava/src/com/google/common/hash/MessageDigestHashFunction.java
index 650d63948020..4726edb8c84c 100644
--- a/guava/src/com/google/common/hash/MessageDigestHashFunction.java
+++ b/guava/src/com/google/common/hash/MessageDigestHashFunction.java
@@ -35,6 +35,7 @@
  * @author Dimitris Andreou
  */
 @Immutable
+@ElementTypesAreNonnullByDefault
 final class MessageDigestHashFunction extends AbstractHashFunction implements Serializable {
 
   @SuppressWarnings("Immutable") // cloned before each use
@@ -44,7 +45,7 @@ final class MessageDigestHashFunction extends AbstractHashFunction implements Se
   private final boolean supportsClone;
   private final String toString;
 
-  @SuppressWarnings("lowerbound:assignment.type.incompatible")/* `prototype.getDigestLength()` returns the digest length in bytes
+  @SuppressWarnings("lowerbound:assignment") /* `prototype.getDigestLength()` returns the digest length in bytes
   ( return 0 as the default behavior).
   */
   MessageDigestHashFunction(String algorithmName, String toString) {
@@ -66,7 +67,7 @@ final class MessageDigestHashFunction extends AbstractHashFunction implements Se
 
   private static boolean supportsClone(MessageDigest digest) {
     try {
-      digest.clone();
+      Object unused = digest.clone();
       return true;
     } catch (CloneNotSupportedException e) {
       return false;
diff --git a/guava/src/com/google/common/hash/Murmur3_128HashFunction.java b/guava/src/com/google/common/hash/Murmur3_128HashFunction.java
index 3218ebff012d..762cc90ccc05 100644
--- a/guava/src/com/google/common/hash/Murmur3_128HashFunction.java
+++ b/guava/src/com/google/common/hash/Murmur3_128HashFunction.java
@@ -31,6 +31,7 @@
 import java.io.Serializable;
 import java.nio.ByteBuffer;
 import java.nio.ByteOrder;
+import javax.annotation.CheckForNull;
 import org.checkerframework.checker.index.qual.NonNegative;
 import org.checkerframework.checker.nullness.qual.Nullable;
 
@@ -42,6 +43,7 @@
  * @author Dimitris Andreou
  */
 @Immutable
+@ElementTypesAreNonnullByDefault
 final class Murmur3_128HashFunction extends AbstractHashFunction implements Serializable {
   static final HashFunction MURMUR3_128 = new Murmur3_128HashFunction(0);
 
@@ -71,7 +73,7 @@ public String toString() {
   }
 
   @Override
-  public boolean equals(@Nullable Object object) {
+  public boolean equals(@CheckForNull Object object) {
     if (object instanceof Murmur3_128HashFunction) {
       Murmur3_128HashFunction other = (Murmur3_128HashFunction) object;
       return seed == other.seed;
@@ -166,8 +168,8 @@ protected void processRemaining(ByteBuffer bb) {
       h2 ^= mixK2(k2);
     }
 
-    @SuppressWarnings("value:argument.type.incompatible")//ByteBuffer#array() should be annotated as  byte @MinLen(1)[] array().
     @Override
+    @SuppressWarnings("value:argument") // ByteBuffer#array() should be annotated as  byte @MinLen(1)[] array().
     protected HashCode makeHash() {
       h1 ^= length;
       h2 ^= length;
diff --git a/guava/src/com/google/common/hash/Murmur3_32HashFunction.java b/guava/src/com/google/common/hash/Murmur3_32HashFunction.java
index 2176bdff5ed4..308ec8dc7db3 100644
--- a/guava/src/com/google/common/hash/Murmur3_32HashFunction.java
+++ b/guava/src/com/google/common/hash/Murmur3_32HashFunction.java
@@ -39,6 +39,7 @@
 import java.nio.ByteBuffer;
 import java.nio.ByteOrder;
 import java.nio.charset.Charset;
+import javax.annotation.CheckForNull;
 import org.checkerframework.checker.index.qual.LTLengthOf;
 import org.checkerframework.checker.index.qual.NonNegative;
 import org.checkerframework.checker.nullness.qual.Nullable;
@@ -54,11 +55,17 @@
  * @author Kurt Alfred Kluever
  */
 @Immutable
+@ElementTypesAreNonnullByDefault
 final class Murmur3_32HashFunction extends AbstractHashFunction implements Serializable {
-  static final HashFunction MURMUR3_32 = new Murmur3_32HashFunction(0);
+  static final HashFunction MURMUR3_32 =
+      new Murmur3_32HashFunction(0, /* supplementaryPlaneFix= */ false);
+  static final HashFunction MURMUR3_32_FIXED =
+      new Murmur3_32HashFunction(0, /* supplementaryPlaneFix= */ true);
 
+  // We can include the non-BMP fix here because Hashing.goodFastHash stresses that the hash is a
+  // temporary-use one. Therefore it shouldn't be persisted.
   static final HashFunction GOOD_FAST_HASH_32 =
-      new Murmur3_32HashFunction(Hashing.GOOD_FAST_HASH_SEED);
+      new Murmur3_32HashFunction(Hashing.GOOD_FAST_HASH_SEED, /* supplementaryPlaneFix= */ true);
 
   private static final int CHUNK_SIZE = 4;
 
@@ -66,9 +73,11 @@ final class Murmur3_32HashFunction extends AbstractHashFunction implements Seria
   private static final int C2 = 0x1b873593;
 
   private final int seed;
+  private final boolean supplementaryPlaneFix;
 
-  Murmur3_32HashFunction(int seed) {
+  Murmur3_32HashFunction(int seed, boolean supplementaryPlaneFix) {
     this.seed = seed;
+    this.supplementaryPlaneFix = supplementaryPlaneFix;
   }
 
   @Override
@@ -87,10 +96,10 @@ public String toString() {
   }
 
   @Override
-  public boolean equals(@Nullable Object object) {
+  public boolean equals(@CheckForNull Object object) {
     if (object instanceof Murmur3_32HashFunction) {
       Murmur3_32HashFunction other = (Murmur3_32HashFunction) object;
-      return seed == other.seed;
+      return seed == other.seed && supplementaryPlaneFix == other.supplementaryPlaneFix;
     }
     return false;
   }
@@ -144,7 +153,7 @@ public HashCode hashUnencodedChars(CharSequence input) {
   }
 
   @SuppressWarnings({"deprecation", // need to use Charsets for Android tests to pass
-          "value:argument.type.incompatible"// Since CharSequence input is annotated to have  minimum length of 1,
+          "value:argument" // Since CharSequence input is annotated to have  minimum length of 1,
           // `input.toString().getBytes(charset)` return a byte array with minimum length of 1.
   })
   @Override
@@ -196,6 +205,9 @@ public HashCode hashString(@MinLen(1) CharSequence input, Charset charset) {
           }
           i++;
           buffer |= codePointToFourUtf8Bytes(codePoint) << shift;
+          if (supplementaryPlaneFix) { // bug compatibility: earlier versions did not have this add
+            shift += 32;
+          }
           len += 4;
         }
 
@@ -342,7 +354,7 @@ public Hasher putChar(char c) {
     }
 
     @SuppressWarnings({"deprecation", // need to use Charsets for Android tests to pass
-            "value:argument.type.incompatible"/*(1) if `charset` is equals to UTF_8, then `putbytes()` is executed.
+            "value:argument" /* if `charset` is equals to UTF_8, then `putbytes()` is executed.
             Since `charset` is equals to `Charsets.UTF_8`, getBytes(charset) return non negative array range.
             */})
     @Override
@@ -400,20 +412,22 @@ public HashCode hash() {
   }
 
   private static long codePointToFourUtf8Bytes(int codePoint) {
-    return (((0xFL << 4) | (codePoint >>> 18)) & 0xFF)
+    // codePoint has at most 21 bits
+    return ((0xFL << 4) | (codePoint >>> 18))
         | ((0x80L | (0x3F & (codePoint >>> 12))) << 8)
         | ((0x80L | (0x3F & (codePoint >>> 6))) << 16)
         | ((0x80L | (0x3F & codePoint)) << 24);
   }
 
   private static long charToThreeUtf8Bytes(char c) {
-    return (((0xF << 5) | (c >>> 12)) & 0xFF)
+    return ((0x7L << 5) | (c >>> 12))
         | ((0x80 | (0x3F & (c >>> 6))) << 8)
         | ((0x80 | (0x3F & c)) << 16);
   }
 
   private static long charToTwoUtf8Bytes(char c) {
-    return (((0xF << 6) | (c >>> 6)) & 0xFF) | ((0x80 | (0x3F & c)) << 8);
+    // c has at most 11 bits
+    return ((0x3L << 6) | (c >>> 6)) | ((0x80 | (0x3F & c)) << 8);
   }
 
   private static final long serialVersionUID = 0L;
diff --git a/guava/src/com/google/common/hash/ParametricNullness.java b/guava/src/com/google/common/hash/ParametricNullness.java
new file mode 100644
index 000000000000..460106c092ea
--- /dev/null
+++ b/guava/src/com/google/common/hash/ParametricNullness.java
@@ -0,0 +1,52 @@
+/*
+ * Copyright (C) 2021 The Guava Authors
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package com.google.common.hash;
+
+import static java.lang.annotation.ElementType.FIELD;
+import static java.lang.annotation.ElementType.METHOD;
+import static java.lang.annotation.ElementType.PARAMETER;
+import static java.lang.annotation.RetentionPolicy.RUNTIME;
+
+import com.google.common.annotations.GwtCompatible;
+import java.lang.annotation.Retention;
+import java.lang.annotation.Target;
+
+/**
+ * Marks a "top-level" type-variable usage as the closest we can get to "non-nullable when
+ * non-nullable; nullable when nullable" (like the Android <a
+ * href="https://android.googlesource.com/platform/libcore/+/master/luni/src/main/java/libcore/util/NullFromTypeParam.java">{@code
+ * NullFromTypeParam}</a>).
+ *
+ * <p>Consumers of this annotation include:
+ *
+ * <ul>
+ *   <li>Kotlin, for which it makes the type-variable usage (a) a Kotlin platform type when the type
+ *       argument is non-nullable and (b) nullable when the type argument is nullable. We use this
+ *       to "undo" {@link ElementTypesAreNonnullByDefault}.
+ *   <li><a href="https://developers.google.com/j2objc">J2ObjC</a>
+ *   <li>{@code NullPointerTester}, at least in the Android backport (where the type-use annotations
+ *       {@code NullPointerTester} would need are not available) and in case of <a
+ *       href="https://bugs.openjdk.java.net/browse/JDK-8202469">JDK-8202469</a>
+ * </ul>
+ *
+ */
+@GwtCompatible
+@Retention(RUNTIME)
+@Target({FIELD, METHOD, PARAMETER})
+@javax.annotation.meta.TypeQualifierNickname
+@javax.annotation.Nonnull(when = javax.annotation.meta.When.UNKNOWN)
+@interface ParametricNullness {}
diff --git a/guava/src/com/google/common/hash/PrimitiveSink.java b/guava/src/com/google/common/hash/PrimitiveSink.java
index b737912c8f5a..1606edbbf885 100644
--- a/guava/src/com/google/common/hash/PrimitiveSink.java
+++ b/guava/src/com/google/common/hash/PrimitiveSink.java
@@ -32,6 +32,7 @@
  */
 @Beta
 @CanIgnoreReturnValue
+@ElementTypesAreNonnullByDefault
 public interface PrimitiveSink {
   /**
    * Puts a byte into this sink.
diff --git a/guava/src/com/google/common/hash/SipHashFunction.java b/guava/src/com/google/common/hash/SipHashFunction.java
index 646eaa9c0fa2..a854db188ff2 100644
--- a/guava/src/com/google/common/hash/SipHashFunction.java
+++ b/guava/src/com/google/common/hash/SipHashFunction.java
@@ -24,6 +24,7 @@
 import com.google.errorprone.annotations.Immutable;
 import java.io.Serializable;
 import java.nio.ByteBuffer;
+import javax.annotation.CheckForNull;
 import org.checkerframework.checker.index.qual.NonNegative;
 import org.checkerframework.checker.nullness.qual.Nullable;
 
@@ -35,6 +36,7 @@
  * @author Daniel J. Bernstein
  */
 @Immutable
+@ElementTypesAreNonnullByDefault
 final class SipHashFunction extends AbstractHashFunction implements Serializable {
   static final HashFunction SIP_HASH_24 =
       new SipHashFunction(2, 4, 0x0706050403020100L, 0x0f0e0d0c0b0a0908L);
@@ -82,7 +84,7 @@ public String toString() {
   }
 
   @Override
-  public boolean equals(@Nullable Object object) {
+  public boolean equals(@CheckForNull Object object) {
     if (object instanceof SipHashFunction) {
       SipHashFunction other = (SipHashFunction) object;
       return (c == other.c) && (d == other.d) && (k0 == other.k0) && (k1 == other.k1);
diff --git a/guava/src/com/google/common/hash/Striped64.java b/guava/src/com/google/common/hash/Striped64.java
index 340f1cae65b4..1daccbe114cf 100644
--- a/guava/src/com/google/common/hash/Striped64.java
+++ b/guava/src/com/google/common/hash/Striped64.java
@@ -13,6 +13,7 @@
 
 import com.google.common.annotations.GwtIncompatible;
 import java.util.Random;
+import javax.annotation.CheckForNull;
 import org.checkerframework.checker.index.qual.NonNegative;
 import org.checkerframework.checker.nullness.qual.Nullable;
 import org.checkerframework.common.value.qual.MinLen;
@@ -23,6 +24,7 @@
  * so.
  */
 @GwtIncompatible
+@ElementTypesAreNonnullByDefault
 abstract class Striped64 extends Number {
   /*
    * This class maintains a lazily-initialized table of atomically
@@ -127,7 +129,7 @@ final boolean cas(long cmp, long val) {
    * class, we use a suboptimal int[] representation to avoid introducing a new type that can impede
    * class-unloading when ThreadLocals are not removed.
    */
-  static final ThreadLocal<int[]> threadHashCode = new ThreadLocal<>();
+  static final ThreadLocal<int @Nullable []> threadHashCode = new ThreadLocal<>();
 
   /** Generator of new random hash codes */
   static final Random rng = new Random();
@@ -136,7 +138,7 @@ final boolean cas(long cmp, long val) {
   static final int NCPU = Runtime.getRuntime().availableProcessors();
 
   /** Table of cells. When non-null, size is a power of 2. */
-  transient volatile Cell @Nullable [] cells;
+  @CheckForNull transient volatile Cell[] cells;
 
   /**
    * Base value, used mainly when there is no contention, but also as a fallback during table
@@ -179,11 +181,12 @@ final boolean casBusy() {
    * @param hc the hash code holder
    * @param wasUncontended false if CAS failed before call
    */
-  @SuppressWarnings({"upperbound:array.access.unsafe.high",//(1) Since `Cell[] rs = new Cell[n << 1]`, rs.length is n * 2.
-  // for loop is executed while i < n, therefore array access is safe.
-          "lowerbound:array.length.negative"//(2) Since int n is annotated as non negative, n << 2 is n * 2 can't be negative
-          })
-  final void retryUpdate(long x, int @Nullable @MinLen(1)[] hc, boolean wasUncontended) {
+  @SuppressWarnings({
+      "upperbound:array.access.unsafe.high", // (1) Since `Cell[] rs = new Cell[n << 1]`, rs.length is n * 2.
+      // for loop is executed while i < n, therefore array access is safe.
+      "lowerbound:array.length.negative" // (2) Since int n is annotated as non negative, n << 2 is n * 2 can't be negative
+  })
+  final void retryUpdate(long x, @CheckForNull int @MinLen(1)[] hc, boolean wasUncontended) {
     int h;
     if (hc == null) {
       threadHashCode.set(hc = new int[1]); // Initialize randomly
diff --git a/guava/src/com/google/common/html/ElementTypesAreNonnullByDefault.java b/guava/src/com/google/common/html/ElementTypesAreNonnullByDefault.java
new file mode 100644
index 000000000000..a28b716632d4
--- /dev/null
+++ b/guava/src/com/google/common/html/ElementTypesAreNonnullByDefault.java
@@ -0,0 +1,41 @@
+/*
+ * Copyright (C) 2021 The Guava Authors
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package com.google.common.html;
+
+import static java.lang.annotation.ElementType.FIELD;
+import static java.lang.annotation.ElementType.METHOD;
+import static java.lang.annotation.ElementType.PARAMETER;
+import static java.lang.annotation.ElementType.TYPE;
+import static java.lang.annotation.RetentionPolicy.RUNTIME;
+
+import com.google.common.annotations.GwtCompatible;
+import java.lang.annotation.Retention;
+import java.lang.annotation.Target;
+import javax.annotation.Nonnull;
+import javax.annotation.meta.TypeQualifierDefault;
+
+/**
+ * Marks all "top-level" types as non-null in a way that is recognized by Kotlin. Note that this
+ * unfortunately includes type-variable usages, so we also provide {@link ParametricNullness} to
+ * "undo" it as best we can.
+ */
+@GwtCompatible
+@Retention(RUNTIME)
+@Target(TYPE)
+@TypeQualifierDefault({FIELD, METHOD, PARAMETER})
+@Nonnull
+@interface ElementTypesAreNonnullByDefault {}
diff --git a/guava/src/com/google/common/html/HtmlEscapers.java b/guava/src/com/google/common/html/HtmlEscapers.java
index 29eebe8aaa46..c42638871507 100644
--- a/guava/src/com/google/common/html/HtmlEscapers.java
+++ b/guava/src/com/google/common/html/HtmlEscapers.java
@@ -35,6 +35,7 @@
  * @since 15.0
  */
 @GwtCompatible
+@ElementTypesAreNonnullByDefault
 public final class HtmlEscapers {
   /**
    * Returns an {@link Escaper} instance that escapes HTML metacharacters as specified by <a
diff --git a/guava/src/com/google/common/html/ParametricNullness.java b/guava/src/com/google/common/html/ParametricNullness.java
new file mode 100644
index 000000000000..61b44616462b
--- /dev/null
+++ b/guava/src/com/google/common/html/ParametricNullness.java
@@ -0,0 +1,52 @@
+/*
+ * Copyright (C) 2021 The Guava Authors
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package com.google.common.html;
+
+import static java.lang.annotation.ElementType.FIELD;
+import static java.lang.annotation.ElementType.METHOD;
+import static java.lang.annotation.ElementType.PARAMETER;
+import static java.lang.annotation.RetentionPolicy.RUNTIME;
+
+import com.google.common.annotations.GwtCompatible;
+import java.lang.annotation.Retention;
+import java.lang.annotation.Target;
+
+/**
+ * Marks a "top-level" type-variable usage as the closest we can get to "non-nullable when
+ * non-nullable; nullable when nullable" (like the Android <a
+ * href="https://android.googlesource.com/platform/libcore/+/master/luni/src/main/java/libcore/util/NullFromTypeParam.java">{@code
+ * NullFromTypeParam}</a>).
+ *
+ * <p>Consumers of this annotation include:
+ *
+ * <ul>
+ *   <li>Kotlin, for which it makes the type-variable usage (a) a Kotlin platform type when the type
+ *       argument is non-nullable and (b) nullable when the type argument is nullable. We use this
+ *       to "undo" {@link ElementTypesAreNonnullByDefault}.
+ *   <li><a href="https://developers.google.com/j2objc">J2ObjC</a>
+ *   <li>{@code NullPointerTester}, at least in the Android backport (where the type-use annotations
+ *       {@code NullPointerTester} would need are not available) and in case of <a
+ *       href="https://bugs.openjdk.java.net/browse/JDK-8202469">JDK-8202469</a>
+ * </ul>
+ *
+ */
+@GwtCompatible
+@Retention(RUNTIME)
+@Target({FIELD, METHOD, PARAMETER})
+@javax.annotation.meta.TypeQualifierNickname
+@javax.annotation.Nonnull(when = javax.annotation.meta.When.UNKNOWN)
+@interface ParametricNullness {}
diff --git a/guava/src/com/google/common/io/AppendableWriter.java b/guava/src/com/google/common/io/AppendableWriter.java
index 512997b950df..1e0c0ec9ad11 100644
--- a/guava/src/com/google/common/io/AppendableWriter.java
+++ b/guava/src/com/google/common/io/AppendableWriter.java
@@ -21,6 +21,7 @@
 import java.io.Flushable;
 import java.io.IOException;
 import java.io.Writer;
+import javax.annotation.CheckForNull;
 import org.checkerframework.checker.index.qual.IndexOrHigh;
 import org.checkerframework.checker.index.qual.LTLengthOf;
 import org.checkerframework.checker.index.qual.NonNegative;
@@ -35,6 +36,7 @@
  * @since 1.0
  */
 @GwtIncompatible
+@ElementTypesAreNonnullByDefault
 class AppendableWriter extends Writer {
   private final Appendable target;
   private boolean closed;
@@ -71,13 +73,15 @@ public void write(int c) throws IOException {
   }
 
   @Override
-  public void write(@Nullable String str) throws IOException {
+  public void write(String str) throws IOException {
+    checkNotNull(str);
     checkNotClosed();
     target.append(str);
   }
 
   @Override
-  public void write(@Nullable String str, @IndexOrHigh("#1") int off, @NonNegative @LTLengthOf(value = "#1", offset = "#2 - 1") int len) throws IOException {
+  public void write(String str, @IndexOrHigh("#1") int off, @NonNegative @LTLengthOf(value = "#1", offset = "#2 - 1") int len) throws IOException {
+    checkNotNull(str);
     checkNotClosed();
     // tricky: append takes start, end pair...
     target.append(str, off, off + len);
@@ -107,14 +111,14 @@ public Writer append(char c) throws IOException {
   }
 
   @Override
-  public Writer append(@Nullable CharSequence charSeq) throws IOException {
+  public Writer append(@CheckForNull CharSequence charSeq) throws IOException {
     checkNotClosed();
     target.append(charSeq);
     return this;
   }
 
   @Override
-  public Writer append(@Nullable CharSequence charSeq, @IndexOrHigh("#1") int start, @IndexOrHigh("#1") int end) throws IOException {
+  public Writer append(@CheckForNull CharSequence charSeq, @IndexOrHigh("#1") int start, @IndexOrHigh("#1") int end) throws IOException {
     checkNotClosed();
     target.append(charSeq, start, end);
     return this;
diff --git a/guava/src/com/google/common/io/BaseEncoding.java b/guava/src/com/google/common/io/BaseEncoding.java
index 4bb682503a77..c85b78a6349e 100644
--- a/guava/src/com/google/common/io/BaseEncoding.java
+++ b/guava/src/com/google/common/io/BaseEncoding.java
@@ -35,6 +35,7 @@
 import java.io.Reader;
 import java.io.Writer;
 import java.util.Arrays;
+import javax.annotation.CheckForNull;
 import org.checkerframework.checker.index.qual.IndexFor;
 import org.checkerframework.checker.index.qual.IndexOrHigh;
 import org.checkerframework.checker.index.qual.LTLengthOf;
@@ -129,6 +130,7 @@
  * @since 14.0
  */
 @GwtCompatible(emulated = true)
+@ElementTypesAreNonnullByDefault
 public abstract class BaseEncoding {
   // TODO(lowasser): consider making encodeTo(Appendable, byte[], int, int) public.
 
@@ -182,7 +184,7 @@ public final String encode(byte[] bytes, @IndexOrHigh("#1") int off, @NonNegativ
    * Returns a {@code ByteSink} that writes base-encoded bytes to the specified {@code CharSink}.
    */
   @GwtIncompatible // ByteSink,CharSink
-  public final ByteSink encodingSink(final CharSink encodedSink) {
+  public final ByteSink encodingSink(CharSink encodedSink) {
     checkNotNull(encodedSink);
     return new ByteSink() {
       @Override
@@ -253,7 +255,7 @@ final byte[] decodeChecked(CharSequence chars)
    * CharSource}.
    */
   @GwtIncompatible // ByteSource,CharSource
-  public final ByteSource decodingSource(final CharSource encodedSource) {
+  public final ByteSource decodingSource(CharSource encodedSource) {
     checkNotNull(encodedSource);
     return new ByteSource() {
       @Override
@@ -554,7 +556,7 @@ public String toString() {
     }
 
     @Override
-    public boolean equals(@Nullable Object other) {
+    public boolean equals(@CheckForNull Object other) {
       if (other instanceof Alphabet) {
         Alphabet that = (Alphabet) other;
         return Arrays.equals(this.chars, that.chars);
@@ -572,13 +574,13 @@ static class StandardBaseEncoding extends BaseEncoding {
     // TODO(lowasser): provide a useful toString
     final Alphabet alphabet;
 
-    final @Nullable Character paddingChar;
+    @CheckForNull final Character paddingChar;
 
-    StandardBaseEncoding(String name, @MinLen(1) String alphabetChars, @Nullable Character paddingChar) {
+    StandardBaseEncoding(String name, @MinLen(1) String alphabetChars, @CheckForNull Character paddingChar) {
       this(new Alphabet(name, alphabetChars.toCharArray()), paddingChar);
     }
 
-    StandardBaseEncoding(Alphabet alphabet, @Nullable Character paddingChar) {
+    StandardBaseEncoding(Alphabet alphabet, @CheckForNull Character paddingChar) {
       this.alphabet = checkNotNull(alphabet);
       checkArgument(
           paddingChar == null || !alphabet.matches(paddingChar),
@@ -594,7 +596,7 @@ static class StandardBaseEncoding extends BaseEncoding {
 
     @GwtIncompatible // Writer,OutputStream
     @Override
-    public OutputStream encodingStream(final Writer out) {
+    public OutputStream encodingStream(Writer out) {
       checkNotNull(out);
       return new OutputStream() {
         int bitBuffer = 0;
@@ -656,7 +658,7 @@ void encodeChunkTo(Appendable target, byte[] bytes, @IndexOrHigh("#2") int off,
         bitBuffer <<= 8; // Add additional zero byte in the end.
       }
       // Position of first character is length of bitBuffer minus bitsPerChar.
-      final int bitOffset = (len + 1) * 8 - alphabet.bitsPerChar;
+      int bitOffset = (len + 1) * 8 - alphabet.bitsPerChar;
       int bitsProcessed = 0;
       while (bitsProcessed < len * 8) {
         @IndexFor("alphabet.chars") int charIndex = (int) (bitBuffer >>> (bitOffset - bitsProcessed)) & alphabet.mask;
@@ -724,7 +726,7 @@ public boolean canDecode(CharSequence chars) {
             chunk |= alphabet.decode(chars.charAt(charIdx + charsProcessed++));
           }
         }
-        final int minOffset = alphabet.bytesPerChunk * 8 - charsProcessed * alphabet.bitsPerChar;
+        int minOffset = alphabet.bytesPerChunk * 8 - charsProcessed * alphabet.bitsPerChar;
         for (int offset = (alphabet.bytesPerChunk - 1) * 8; offset >= minOffset; offset -= 8) {
           target[bytesWritten++] = (byte) ((chunk >>> offset) & 0xFF);
         }
@@ -734,7 +736,7 @@ public boolean canDecode(CharSequence chars) {
 
     @Override
     @GwtIncompatible // Reader,InputStream
-    public InputStream decodingStream(final Reader reader) {
+    public InputStream decodingStream(Reader reader) {
       checkNotNull(reader);
       return new InputStream() {
         int bitBuffer = 0;
@@ -836,8 +838,8 @@ public BaseEncoding withSeparator(String separator, @NonNegative int afterEveryC
       return new SeparatedBaseEncoding(this, separator, afterEveryChars);
     }
 
-    @LazyInit private transient @Nullable BaseEncoding upperCase;
-    @LazyInit private transient @Nullable BaseEncoding lowerCase;
+    @LazyInit @CheckForNull private transient BaseEncoding upperCase;
+    @LazyInit @CheckForNull private transient BaseEncoding lowerCase;
 
     @Override
     public BaseEncoding upperCase() {
@@ -859,7 +861,7 @@ public BaseEncoding lowerCase() {
       return result;
     }
 
-    BaseEncoding newInstance(Alphabet alphabet, @Nullable Character paddingChar) {
+    BaseEncoding newInstance(Alphabet alphabet, @CheckForNull Character paddingChar) {
       return new StandardBaseEncoding(alphabet, paddingChar);
     }
 
@@ -878,7 +880,7 @@ public String toString() {
     }
 
     @Override
-    public boolean equals(@Nullable Object other) {
+    public boolean equals(@CheckForNull Object other) {
       if (other instanceof StandardBaseEncoding) {
         StandardBaseEncoding that = (StandardBaseEncoding) other;
         return this.alphabet.equals(that.alphabet)
@@ -935,17 +937,17 @@ void encodeTo(Appendable target, byte[] bytes, @IndexOrHigh("#2") int off, @NonN
     }
 
     @Override
-    BaseEncoding newInstance(Alphabet alphabet, @Nullable Character paddingChar) {
+    BaseEncoding newInstance(Alphabet alphabet, @CheckForNull Character paddingChar) {
       return new Base16Encoding(alphabet);
     }
   }
 
   static final class Base64Encoding extends StandardBaseEncoding {
-    Base64Encoding(String name, @ArrayLen(64) String alphabetChars, @Nullable Character paddingChar) {
+    Base64Encoding(String name, @ArrayLen(64) String alphabetChars, @CheckForNull Character paddingChar) {
       this(new Alphabet(name, alphabetChars.toCharArray()), paddingChar);
     }
 
-    private Base64Encoding(Alphabet alphabet, @Nullable Character paddingChar) {
+    private Base64Encoding(Alphabet alphabet, @CheckForNull Character paddingChar) {
       super(alphabet, paddingChar);
       checkArgument(alphabet.chars.length == 64);
     }
@@ -992,13 +994,13 @@ void encodeTo(Appendable target, byte[] bytes, @IndexOrHigh("#2") int off, @NonN
     }
 
     @Override
-    BaseEncoding newInstance(Alphabet alphabet, @Nullable Character paddingChar) {
+    BaseEncoding newInstance(Alphabet alphabet, @CheckForNull Character paddingChar) {
       return new Base64Encoding(alphabet, paddingChar);
     }
   }
 
   @GwtIncompatible
-  static Reader ignoringReader(final Reader delegate, final String toIgnore) {
+  static Reader ignoringReader(Reader delegate, String toIgnore) {
     checkNotNull(delegate);
     checkNotNull(toIgnore);
     return new Reader() {
@@ -1024,7 +1026,7 @@ public void close() throws IOException {
   }
 
   static Appendable separatingAppendable(
-      final Appendable delegate, final String separator, final @NonNegative int afterEveryChars) {
+      Appendable delegate, String separator, @NonNegative int afterEveryChars) {
     checkNotNull(delegate);
     checkNotNull(separator);
     checkArgument(afterEveryChars > 0);
@@ -1043,22 +1045,20 @@ public Appendable append(char c) throws IOException {
       }
 
       @Override
-      public Appendable append(@Nullable CharSequence chars, int off, int len) throws IOException {
+      public Appendable append(@CheckForNull CharSequence chars, int off, int len) {
         throw new UnsupportedOperationException();
       }
 
       @Override
-      public Appendable append(@Nullable CharSequence chars) throws IOException {
+      public Appendable append(@CheckForNull CharSequence chars) {
         throw new UnsupportedOperationException();
       }
     };
   }
 
   @GwtIncompatible // Writer
-  static Writer separatingWriter(
-      final Writer delegate, final String separator, final @NonNegative int afterEveryChars) {
-    final Appendable separatingAppendable =
-        separatingAppendable(delegate, separator, afterEveryChars);
+  static Writer separatingWriter(Writer delegate, String separator, @NonNegative int afterEveryChars) {
+    Appendable separatingAppendable = separatingAppendable(delegate, separator, afterEveryChars);
     return new Writer() {
       @Override
       @SuppressWarnings("signedness:cast.unsafe")  // can't prove c fits in a char???
@@ -1110,7 +1110,7 @@ CharSequence trimTrailingPadding(CharSequence chars) {
 
     @GwtIncompatible // Writer,OutputStream
     @Override
-    public OutputStream encodingStream(final Writer output) {
+    public OutputStream encodingStream(Writer output) {
       return delegate.encodingStream(separatingWriter(output, separator, afterEveryChars));
     }
 
@@ -1150,7 +1150,7 @@ public boolean canDecode(CharSequence chars) {
 
     @Override
     @GwtIncompatible // Reader,InputStream
-    public InputStream decodingStream(final Reader reader) {
+    public InputStream decodingStream(Reader reader) {
       return delegate.decodingStream(ignoringReader(reader, separator));
     }
 
diff --git a/guava/src/com/google/common/io/ByteArrayDataInput.java b/guava/src/com/google/common/io/ByteArrayDataInput.java
index f41588e66f5f..3af17d12dd2c 100644
--- a/guava/src/com/google/common/io/ByteArrayDataInput.java
+++ b/guava/src/com/google/common/io/ByteArrayDataInput.java
@@ -18,6 +18,7 @@
 import com.google.errorprone.annotations.CanIgnoreReturnValue;
 import java.io.DataInput;
 import java.io.IOException;
+import javax.annotation.CheckForNull;
 import org.checkerframework.checker.index.qual.IndexOrHigh;
 import org.checkerframework.checker.index.qual.LTLengthOf;
 import org.checkerframework.checker.index.qual.NonNegative;
@@ -35,6 +36,7 @@
  * @since 1.0
  */
 @GwtIncompatible
+@ElementTypesAreNonnullByDefault
 public interface ByteArrayDataInput extends DataInput {
   @Override
   void readFully(byte b[]);
@@ -89,6 +91,7 @@ public interface ByteArrayDataInput extends DataInput {
 
   @CanIgnoreReturnValue // to skip a line
   @Override
+  @CheckForNull
   String readLine();
 
   @CanIgnoreReturnValue // to skip a field
diff --git a/guava/src/com/google/common/io/ByteArrayDataOutput.java b/guava/src/com/google/common/io/ByteArrayDataOutput.java
index f666d55cf810..16660deae704 100644
--- a/guava/src/com/google/common/io/ByteArrayDataOutput.java
+++ b/guava/src/com/google/common/io/ByteArrayDataOutput.java
@@ -29,6 +29,7 @@
  * @since 1.0
  */
 @GwtIncompatible
+@ElementTypesAreNonnullByDefault
 public interface ByteArrayDataOutput extends DataOutput {
   @Override
   void write(int b);
diff --git a/guava/src/com/google/common/io/ByteProcessor.java b/guava/src/com/google/common/io/ByteProcessor.java
index 9c0072a71029..2245c7bdf0e8 100644
--- a/guava/src/com/google/common/io/ByteProcessor.java
+++ b/guava/src/com/google/common/io/ByteProcessor.java
@@ -22,6 +22,7 @@
 import org.checkerframework.checker.index.qual.LTLengthOf;
 import org.checkerframework.checker.index.qual.NonNegative;
 import java.io.IOException;
+import org.checkerframework.checker.nullness.qual.Nullable;
 
 /**
  * A callback interface to process bytes from a stream.
@@ -35,7 +36,8 @@
 @Beta
 @DoNotMock("Implement it normally")
 @GwtIncompatible
-public interface ByteProcessor<T> {
+@ElementTypesAreNonnullByDefault
+public interface ByteProcessor<T extends @Nullable Object> {
   /**
    * This method will be called for each chunk of bytes in an input stream. The implementation
    * should process the bytes from {@code buf[off]} through {@code buf[off + len - 1]} (inclusive).
@@ -49,5 +51,6 @@ public interface ByteProcessor<T> {
   boolean processBytes(byte[] buf, @IndexOrHigh("#1") int off, @NonNegative @LTLengthOf(value = "#1", offset = "#2 - 1") int len) throws IOException;
 
   /** Return the result of processing all the bytes. */
+  @ParametricNullness
   T getResult();
 }
diff --git a/guava/src/com/google/common/io/ByteSink.java b/guava/src/com/google/common/io/ByteSink.java
index ffba6e0a928c..7a6af6fc588b 100644
--- a/guava/src/com/google/common/io/ByteSink.java
+++ b/guava/src/com/google/common/io/ByteSink.java
@@ -46,6 +46,7 @@
  * @author Colin Decker
  */
 @GwtIncompatible
+@ElementTypesAreNonnullByDefault
 public abstract class ByteSink {
 
   /** Constructor for use by subclasses. */
diff --git a/guava/src/com/google/common/io/ByteSource.java b/guava/src/com/google/common/io/ByteSource.java
index bb9e171e3b42..594e14687175 100644
--- a/guava/src/com/google/common/io/ByteSource.java
+++ b/guava/src/com/google/common/io/ByteSource.java
@@ -40,6 +40,7 @@
 import java.util.Arrays;
 import java.util.Collection;
 import java.util.Iterator;
+import org.checkerframework.checker.nullness.qual.Nullable;
 import org.checkerframework.checker.index.qual.IndexOrHigh;
 import org.checkerframework.checker.index.qual.LTLengthOf;
 import org.checkerframework.checker.index.qual.NonNegative;
@@ -60,10 +61,23 @@
  *       doing something and finally closing the stream that was opened.
  * </ul>
  *
+ * <p><b>Note:</b> In general, {@code ByteSource} is intended to be used for "file-like" sources
+ * that provide streams that are:
+ *
+ * <ul>
+ *   <li><b>Finite:</b> Many operations, such as {@link #size()} and {@link #read()}, will either
+ *       block indefinitely or fail if the source creates an infinite stream.
+ *   <li><b>Non-destructive:</b> A <i>destructive</i> stream will consume or otherwise alter the
+ *       bytes of the source as they are read from it. A source that provides such streams will not
+ *       be reusable, and operations that read from the stream (including {@link #size()}, in some
+ *       implementations) will prevent further operations from completing as expected.
+ * </ul>
+ *
  * @since 14.0
  * @author Colin Decker
  */
 @GwtIncompatible
+@ElementTypesAreNonnullByDefault
 public abstract class ByteSource {
 
   /** Constructor for use by subclasses. */
@@ -305,7 +319,7 @@ public byte[] read() throws IOException {
    */
   @Beta
   @CanIgnoreReturnValue // some processors won't return a useful result
-  public <T> T read(ByteProcessor<T> processor) throws IOException {
+  public <T extends @Nullable Object> T read(ByteProcessor<T> processor) throws IOException {
     checkNotNull(processor);
 
     Closer closer = Closer.create();
@@ -419,7 +433,7 @@ public static ByteSource concat(ByteSource... sources) {
    * Returns a view of the given byte array as a {@link ByteSource}. To view only a specific range
    * in the array, use {@code ByteSource.wrap(b).slice(offset, length)}.
    *
-   * <p>Note that the given byte array may be be passed directly to methods on, for example, {@code
+   * <p>Note that the given byte array may be passed directly to methods on, for example, {@code
    * OutputStream} (when {@code copyTo(OutputStream)} is called on the resulting {@code
    * ByteSource}). This could allow a malicious {@code OutputStream} implementation to modify the
    * contents of the array, but provides better performance in the normal case.
@@ -609,7 +623,8 @@ public byte[] read() {
 
     @SuppressWarnings("CheckReturnValue") // it doesn't matter what processBytes returns here
     @Override
-    public <T> T read(ByteProcessor<T> processor) throws IOException {
+    @ParametricNullness
+    public <T extends @Nullable Object> T read(ByteProcessor<T> processor) throws IOException {
       processor.processBytes(bytes, offset, length);
       return processor.getResult();
     }
diff --git a/guava/src/com/google/common/io/ByteStreams.java b/guava/src/com/google/common/io/ByteStreams.java
index 9809a873d660..16e1dcc14ed5 100644
--- a/guava/src/com/google/common/io/ByteStreams.java
+++ b/guava/src/com/google/common/io/ByteStreams.java
@@ -18,6 +18,8 @@
 import static com.google.common.base.Preconditions.checkNotNull;
 import static com.google.common.base.Preconditions.checkPositionIndex;
 import static com.google.common.base.Preconditions.checkPositionIndexes;
+import static java.lang.Math.max;
+import static java.lang.Math.min;
 
 import com.google.common.annotations.Beta;
 import com.google.common.annotations.GwtIncompatible;
@@ -50,6 +52,8 @@
 import org.checkerframework.checker.signedness.qual.PolySigned;
 import java.util.Deque;
 import java.util.Queue;
+import javax.annotation.CheckForNull;
+import org.checkerframework.checker.nullness.qual.Nullable;
 
 /**
  * Provides utility methods for working with byte arrays and I/O streams.
@@ -59,6 +63,7 @@
  * @since 1.0
  */
 @GwtIncompatible
+@ElementTypesAreNonnullByDefault
 public final class ByteStreams {
 
   private static final int BUFFER_SIZE = 8192;
@@ -176,13 +181,18 @@ public static long copy(ReadableByteChannel from, WritableByteChannel to) throws
    */
   private static byte[] toByteArrayInternal(InputStream in, Queue<byte[]> bufs, @NonNegative int totalLen)
       throws IOException {
-    // Starting with an 8k buffer, double the size of each successive buffer. Buffers are retained
-    // in a deque so that there's no copying between buffers while reading and so all of the bytes
-    // in each new allocated buffer are available for reading from the stream.
-    for (int bufSize = BUFFER_SIZE;
+    // Roughly size to match what has been read already. Some file systems, such as procfs, return 0
+    // as their length. These files are very small, so it's wasteful to allocate an 8KB buffer.
+    int initialBufferSize = min(BUFFER_SIZE, max(128, Integer.highestOneBit(totalLen) * 2));
+    // Starting with an 8k buffer, double the size of each successive buffer. Smaller buffers
+    // quadruple in size until they reach 8k, to minimize the number of small reads for longer
+    // streams. Buffers are retained in a deque so that there's no copying between buffers while
+    // reading and so all of the bytes in each new allocated buffer are available for reading from
+    // the stream.
+    for (int bufSize = initialBufferSize;
         totalLen < MAX_ARRAY_LEN;
-        bufSize = IntMath.saturatedMultiply(bufSize, 2)) {
-      byte[] buf = new byte[Math.min(bufSize, MAX_ARRAY_LEN - totalLen)];
+        bufSize = IntMath.saturatedMultiply(bufSize, bufSize < 4096 ? 4 : 2)) {
+      byte[] buf = new byte[min(bufSize, MAX_ARRAY_LEN - totalLen)];
       bufs.add(buf);
       int off = 0;
       while (off < buf.length) {
@@ -206,11 +216,18 @@ private static byte[] toByteArrayInternal(InputStream in, Queue<byte[]> bufs, @N
   }
 
   private static byte[] combineBuffers(Queue<byte[]> bufs, @NonNegative int totalLen) {
-    byte[] result = new byte[totalLen];
-    int remaining = totalLen;
+    if (bufs.isEmpty()) {
+      return new byte[0];
+    }
+    byte[] result = bufs.remove();
+    if (result.length == totalLen) {
+      return result;
+    }
+    int remaining = totalLen - result.length;
+    result = Arrays.copyOf(result, totalLen);
     while (remaining > 0) {
       byte[] buf = bufs.remove();
-      int bytesToCopy = Math.min(remaining, buf.length);
+      int bytesToCopy = min(remaining, buf.length);
       int resultOffset = totalLen - remaining;
       System.arraycopy(buf, 0, result, resultOffset, bytesToCopy);
       remaining -= bytesToCopy;
@@ -262,7 +279,7 @@ static byte[] toByteArray(InputStream in, @NonNegative long expectedSize) throws
     }
 
     // the stream was longer, so read the rest normally
-    Queue<byte[]> bufs = new ArrayDeque<byte[]>(TO_BYTE_ARRAY_DEQUE_SIZE + 2);
+    Queue<byte[]> bufs = new ArrayDeque<>(TO_BYTE_ARRAY_DEQUE_SIZE + 2);
     bufs.add(bytes);
     bufs.add(new byte[] {(byte) b});
     return toByteArrayInternal(in, bufs, bytes.length + 1);
@@ -447,6 +464,7 @@ public double readDouble() {
     }
 
     @Override
+    @CheckForNull
     public String readLine() {
       try {
         return input.readLine();
@@ -662,6 +680,7 @@ public void write(@PolySigned byte[] b) {
         @Override
         public void write(@PolySigned byte[] b, @IndexOrHigh("#1") int off, @NonNegative @LTLengthOf(value = "#1", offset = "#2 - 1") int len) {
           checkNotNull(b);
+          checkPositionIndexes(off, off + len, b.length);
         }
 
         @Override
@@ -824,7 +843,7 @@ public static void skipFully(InputStream in, long n) throws IOException {
    * either the full amount has been skipped or until the end of the stream is reached, whichever
    * happens first. Returns the total number of bytes skipped.
    */
-  static long skipUpTo(InputStream in, final long n) throws IOException {
+  static long skipUpTo(InputStream in, long n) throws IOException {
     long totalSkipped = 0;
     // A buffer is allocated if skipSafely does not skip any bytes.
     byte[] buf = null;
@@ -878,7 +897,9 @@ static long skipUpTo(InputStream in, final long n) throws IOException {
    */
   @Beta
   @CanIgnoreReturnValue // some processors won't return a useful result
-  public static <T> T readBytes(InputStream input, ByteProcessor<T> processor) throws IOException {
+  @ParametricNullness
+  public static <T extends @Nullable Object> T readBytes(
+      InputStream input, ByteProcessor<T> processor) throws IOException {
     checkNotNull(input);
     checkNotNull(processor);
 
diff --git a/guava/src/com/google/common/io/CharSequenceReader.java b/guava/src/com/google/common/io/CharSequenceReader.java
index ae2768bc3c8b..2bff4c38eca5 100644
--- a/guava/src/com/google/common/io/CharSequenceReader.java
+++ b/guava/src/com/google/common/io/CharSequenceReader.java
@@ -17,11 +17,13 @@
 import static com.google.common.base.Preconditions.checkArgument;
 import static com.google.common.base.Preconditions.checkNotNull;
 import static com.google.common.base.Preconditions.checkPositionIndexes;
+import static java.util.Objects.requireNonNull;
 
 import com.google.common.annotations.GwtIncompatible;
 import java.io.IOException;
 import java.io.Reader;
 import java.nio.CharBuffer;
+import javax.annotation.CheckForNull;
 import org.checkerframework.checker.index.qual.GTENegativeOne;
 import org.checkerframework.checker.index.qual.IndexOrHigh;
 import org.checkerframework.checker.index.qual.LTEqLengthOf;
@@ -36,9 +38,10 @@
  */
 // TODO(cgdecker): make this public? as a type, or a method in CharStreams?
 @GwtIncompatible
+@ElementTypesAreNonnullByDefault
 final class CharSequenceReader extends Reader {
 
-  private CharSequence seq;
+  @CheckForNull private CharSequence seq;
   private int pos;
   private int mark;
 
@@ -57,16 +60,30 @@ private boolean hasRemaining() {
     return remaining() > 0;
   }
 
-  @SuppressWarnings("return.type.incompatible") // The method is private and every place it is used returns a non-negative value.
+  @SuppressWarnings("index:return") // The method is private and every place it is used returns a non-negative value.
   private @NonNegative int remaining() {
+    requireNonNull(seq); // safe as long as we call this only after checkOpen
     return seq.length() - pos;
   }
 
+  /*
+   * To avoid the need to call requireNonNull so much, we could consider more clever approaches,
+   * such as:
+   *
+   * - Make checkOpen return the non-null `seq`. Then callers can assign that to a local variable or
+   *   even back to `this.seq`. However, that may suggest that we're defending against concurrent
+   *   mutation, which is not an actual risk because we use `synchronized`.
+   * - Make `remaining` require a non-null `seq` argument. But this is a bit weird because the
+   *   method, while it would avoid the instance field `seq` would still access the instance field
+   *   `pos`.
+   */
+
   @Override
-  @SuppressWarnings("argument.type.incompatible") // pos is a valid index for seq because the loop stops at charsToRead steps, which cannot exceed the limit of target or seq.
+  @SuppressWarnings("index:argument") // pos is a valid index for seq because the loop stops at charsToRead steps, which cannot exceed the limit of target or seq.
   public synchronized @GTENegativeOne int read(CharBuffer target) throws IOException {
     checkNotNull(target);
     checkOpen();
+    requireNonNull(seq); // safe because of checkOpen
     if (!hasRemaining()) {
       return -1;
     }
@@ -78,20 +95,22 @@ private boolean hasRemaining() {
   }
 
   @Override
-  @SuppressWarnings({"return.type.incompatible", "argument.type.incompatible"}) /* charAt returns a char, which is known to be non-negative Ascii.
+  @SuppressWarnings({"index:return", "index:argument"}) /* charAt returns a char, which is known to be non-negative Ascii.
   pos is a valid index for seq because hasRemaining() would otherwise return false */
   public synchronized @GTENegativeOne int read() throws IOException {
     checkOpen();
+    requireNonNull(seq); // safe because of checkOpen
     return hasRemaining() ? seq.charAt(pos++) : -1;
   }
 
   @Override
-  @SuppressWarnings({"argument.type.incompatible", "return.type.incompatible"}) /*
+  @SuppressWarnings({"index:argument", "index:return"}) /*
   #1. pos is a valid index for seq because the loop stops at charsToRead steps, which cannot exceed the limit of seq.
   #2. charsToRead is at most equal to len, which is known to be below the length of cbuf */
   public synchronized @GTENegativeOne @LTEqLengthOf("#1") int read(char[] cbuf, @IndexOrHigh("#1") int off, @NonNegative @LTLengthOf(value = "#1", offset = "#2 - 1") int len) throws IOException {
     checkPositionIndexes(off, off + len, cbuf.length);
     checkOpen();
+    requireNonNull(seq); // safe because of checkOpen
     if (!hasRemaining()) {
       return -1;
     }
diff --git a/guava/src/com/google/common/io/CharSink.java b/guava/src/com/google/common/io/CharSink.java
index 7197265df55c..f804daeb7a38 100644
--- a/guava/src/com/google/common/io/CharSink.java
+++ b/guava/src/com/google/common/io/CharSink.java
@@ -51,6 +51,7 @@
  * @author Colin Decker
  */
 @GwtIncompatible
+@ElementTypesAreNonnullByDefault
 public abstract class CharSink {
 
   /** Constructor for use by subclasses. */
diff --git a/guava/src/com/google/common/io/CharSource.java b/guava/src/com/google/common/io/CharSource.java
index ac3df0c87cc1..24a67af5c6e7 100644
--- a/guava/src/com/google/common/io/CharSource.java
+++ b/guava/src/com/google/common/io/CharSource.java
@@ -39,6 +39,7 @@
 import java.util.List;
 import java.util.function.Consumer;
 import java.util.stream.Stream;
+import javax.annotation.CheckForNull;
 import org.checkerframework.checker.nullness.qual.Nullable;
 
 /**
@@ -65,10 +66,23 @@
  * <p>Any {@link ByteSource} containing text encoded with a specific {@linkplain Charset character
  * encoding} may be viewed as a {@code CharSource} using {@link ByteSource#asCharSource(Charset)}.
  *
+ * <p><b>Note:</b> In general, {@code CharSource} is intended to be used for "file-like" sources
+ * that provide readers that are:
+ *
+ * <ul>
+ *   <li><b>Finite:</b> Many operations, such as {@link #length()} and {@link #read()}, will either
+ *       block indefinitely or fail if the source creates an infinite reader.
+ *   <li><b>Non-destructive:</b> A <i>destructive</i> reader will consume or otherwise alter the
+ *       source as they are read from it. A source that provides such readers will not be reusable,
+ *       and operations that read from the stream (including {@link #length()}, in some
+ *       implementations) will prevent further operations from completing as expected.
+ * </ul>
+ *
  * @since 14.0
  * @author Colin Decker
  */
 @GwtIncompatible
+@ElementTypesAreNonnullByDefault
 public abstract class CharSource {
 
   /** Constructor for use by subclasses. */
@@ -295,7 +309,8 @@ public String read() throws IOException {
    *
    * @throws IOException if an I/O error occurs while reading from this source
    */
-  public @Nullable String readFirstLine() throws IOException {
+  @CheckForNull
+  public String readFirstLine() throws IOException {
     Closer closer = Closer.create();
     try {
       BufferedReader reader = closer.register(openBufferedStream());
@@ -351,7 +366,8 @@ public ImmutableList<String> readLines() throws IOException {
    */
   @Beta
   @CanIgnoreReturnValue // some processors won't return a useful result
-  public <T> T readLines(LineProcessor<T> processor) throws IOException {
+  @ParametricNullness
+  public <T extends @Nullable Object> T readLines(LineProcessor<T> processor) throws IOException {
     checkNotNull(processor);
 
     Closer closer = Closer.create();
@@ -563,6 +579,7 @@ private Iterator<String> linesIterator() {
         Iterator<String> lines = LINE_SPLITTER.split(seq).iterator();
 
         @Override
+        @CheckForNull
         protected String computeNext() {
           if (lines.hasNext()) {
             String next = lines.next();
@@ -582,6 +599,7 @@ public Stream<String> lines() {
     }
 
     @Override
+    @CheckForNull
     public String readFirstLine() {
       Iterator<String> lines = linesIterator();
       return lines.hasNext() ? lines.next() : null;
@@ -593,7 +611,8 @@ public ImmutableList<String> readLines() {
     }
 
     @Override
-    public <T> T readLines(LineProcessor<T> processor) throws IOException {
+    @ParametricNullness
+    public <T extends @Nullable Object> T readLines(LineProcessor<T> processor) throws IOException {
       Iterator<String> lines = linesIterator();
       while (lines.hasNext()) {
         if (!processor.processLine(lines.next())) {
diff --git a/guava/src/com/google/common/io/CharStreams.java b/guava/src/com/google/common/io/CharStreams.java
index 5120a702d0f2..625275d9308c 100644
--- a/guava/src/com/google/common/io/CharStreams.java
+++ b/guava/src/com/google/common/io/CharStreams.java
@@ -28,6 +28,7 @@
 import java.nio.CharBuffer;
 import java.util.ArrayList;
 import java.util.List;
+import javax.annotation.CheckForNull;
 import org.checkerframework.checker.index.qual.IndexOrHigh;
 import org.checkerframework.checker.index.qual.LTLengthOf;
 import org.checkerframework.checker.index.qual.NonNegative;
@@ -36,8 +37,6 @@
 /**
  * Provides utility methods for working with character streams.
  *
- * <p>All method parameters must be non-null unless documented otherwise.
- *
  * <p>Some of the methods in this class take arguments with a generic type of {@code Readable &
  * Closeable}. A {@link java.io.Reader} implements both of those interfaces. Similarly for {@code
  * Appendable & Closeable} and {@link java.io.Writer}.
@@ -48,6 +47,7 @@
  * @since 1.0
  */
 @GwtIncompatible
+@ElementTypesAreNonnullByDefault
 public final class CharStreams {
 
   // 2K chars (4K bytes)
@@ -218,7 +218,9 @@ public static List<String> readLines(Readable r) throws IOException {
    */
   @Beta
   @CanIgnoreReturnValue // some processors won't return a useful result
-  public static <T> T readLines(Readable readable, LineProcessor<T> processor) throws IOException {
+  @ParametricNullness
+  public static <T extends @Nullable Object> T readLines(
+      Readable readable, LineProcessor<T> processor) throws IOException {
     checkNotNull(readable);
     checkNotNull(processor);
 
@@ -310,12 +312,12 @@ public void write(String str, @IndexOrHigh("#1") int off, @NonNegative @LTLength
     }
 
     @Override
-    public Writer append(@Nullable CharSequence csq) {
+    public Writer append(@CheckForNull CharSequence csq) {
       return this;
     }
 
     @Override
-    public Writer append(@Nullable CharSequence csq, @IndexOrHigh("#1") int start, @IndexOrHigh("#1") int end) {
+    public Writer append(@CheckForNull CharSequence csq, @IndexOrHigh("#1") int start, @IndexOrHigh("#1") int end) {
       checkPositionIndexes(start, end, csq == null ? "null".length() : csq.length());
       return this;
     }
diff --git a/guava/src/com/google/common/io/Closeables.java b/guava/src/com/google/common/io/Closeables.java
index 3adcb1920275..b45f5f0fde65 100644
--- a/guava/src/com/google/common/io/Closeables.java
+++ b/guava/src/com/google/common/io/Closeables.java
@@ -23,7 +23,7 @@
 import java.io.Reader;
 import java.util.logging.Level;
 import java.util.logging.Logger;
-import org.checkerframework.checker.nullness.qual.Nullable;
+import javax.annotation.CheckForNull;
 
 /**
  * Utility methods for working with {@link Closeable} objects.
@@ -33,6 +33,7 @@
  */
 @Beta
 @GwtIncompatible
+@ElementTypesAreNonnullByDefault
 public final class Closeables {
   @VisibleForTesting static final Logger logger = Logger.getLogger(Closeables.class.getName());
 
@@ -69,7 +70,7 @@ private Closeables() {}
    * @throws IOException if {@code swallowIOException} is false and {@code close} throws an {@code
    *     IOException}.
    */
-  public static void close(@Nullable Closeable closeable, boolean swallowIOException)
+  public static void close(@CheckForNull Closeable closeable, boolean swallowIOException)
       throws IOException {
     if (closeable == null) {
       return;
@@ -99,7 +100,7 @@ public static void close(@Nullable Closeable closeable, boolean swallowIOExcepti
    *     does nothing
    * @since 17.0
    */
-  public static void closeQuietly(@Nullable InputStream inputStream) {
+  public static void closeQuietly(@CheckForNull InputStream inputStream) {
     try {
       close(inputStream, true);
     } catch (IOException impossible) {
@@ -120,7 +121,7 @@ public static void closeQuietly(@Nullable InputStream inputStream) {
    * @param reader the reader to be closed, or {@code null} in which case this method does nothing
    * @since 17.0
    */
-  public static void closeQuietly(@Nullable Reader reader) {
+  public static void closeQuietly(@CheckForNull Reader reader) {
     try {
       close(reader, true);
     } catch (IOException impossible) {
diff --git a/guava/src/com/google/common/io/Closer.java b/guava/src/com/google/common/io/Closer.java
index 82cfcb48dc86..12998eff95bb 100644
--- a/guava/src/com/google/common/io/Closer.java
+++ b/guava/src/com/google/common/io/Closer.java
@@ -27,6 +27,7 @@
 import java.util.ArrayDeque;
 import java.util.Deque;
 import java.util.logging.Level;
+import javax.annotation.CheckForNull;
 import org.checkerframework.checker.nullness.qual.Nullable;
 
 /**
@@ -88,13 +89,16 @@
 // Coffee's for {@link Closer closers} only.
 @Beta
 @GwtIncompatible
+@ElementTypesAreNonnullByDefault
 public final class Closer implements Closeable {
 
   /** The suppressor implementation to use for the current Java version. */
-  private static final Suppressor SUPPRESSOR =
-      SuppressingSuppressor.isAvailable()
-          ? SuppressingSuppressor.INSTANCE
-          : LoggingSuppressor.INSTANCE;
+  private static final Suppressor SUPPRESSOR;
+
+  static {
+    SuppressingSuppressor suppressingSuppressor = SuppressingSuppressor.tryCreate();
+    SUPPRESSOR = suppressingSuppressor == null ? LoggingSuppressor.INSTANCE : suppressingSuppressor;
+  }
 
   /** Creates a new {@link Closer}. */
   public static Closer create() {
@@ -105,7 +109,7 @@ public static Closer create() {
 
   // only need space for 2 elements in most cases, so try to use the smallest array possible
   private final Deque<Closeable> stack = new ArrayDeque<>(4);
-  private @Nullable Throwable thrown;
+  @CheckForNull private Throwable thrown;
 
   @VisibleForTesting
   Closer(Suppressor suppressor) {
@@ -120,7 +124,8 @@ public static Closer create() {
    */
   // close. this word no longer has any meaning to me.
   @CanIgnoreReturnValue
-  public <C extends Closeable> C register(@Nullable C closeable) {
+  @ParametricNullness
+  public <C extends @Nullable Closeable> C register(@ParametricNullness C closeable) {
     if (closeable != null) {
       stack.addFirst(closeable);
     }
@@ -257,21 +262,21 @@ public void suppress(Closeable closeable, Throwable thrown, Throwable suppressed
    */
   @VisibleForTesting
   static final class SuppressingSuppressor implements Suppressor {
-
-    static final SuppressingSuppressor INSTANCE = new SuppressingSuppressor();
-
-    static boolean isAvailable() {
-      return addSuppressed != null;
-    }
-
-    static final Method addSuppressed = addSuppressedMethodOrNull();
-
-    private static Method addSuppressedMethodOrNull() {
+    @CheckForNull
+    static SuppressingSuppressor tryCreate() {
+      Method addSuppressed;
       try {
-        return Throwable.class.getMethod("addSuppressed", Throwable.class);
+        addSuppressed = Throwable.class.getMethod("addSuppressed", Throwable.class);
       } catch (Throwable e) {
         return null;
       }
+      return new SuppressingSuppressor(addSuppressed);
+    }
+
+    private final Method addSuppressed;
+
+    private SuppressingSuppressor(Method addSuppressed) {
+      this.addSuppressed = addSuppressed;
     }
 
     @Override
diff --git a/guava/src/com/google/common/io/CountingInputStream.java b/guava/src/com/google/common/io/CountingInputStream.java
index 0d13a2298a6a..9528d667f1d4 100644
--- a/guava/src/com/google/common/io/CountingInputStream.java
+++ b/guava/src/com/google/common/io/CountingInputStream.java
@@ -35,6 +35,7 @@
  */
 @Beta
 @GwtIncompatible
+@ElementTypesAreNonnullByDefault
 public final class CountingInputStream extends FilterInputStream {
 
   private long count;
diff --git a/guava/src/com/google/common/io/CountingOutputStream.java b/guava/src/com/google/common/io/CountingOutputStream.java
index 07e36d71f177..b2ca17c5f7a8 100644
--- a/guava/src/com/google/common/io/CountingOutputStream.java
+++ b/guava/src/com/google/common/io/CountingOutputStream.java
@@ -31,6 +31,7 @@
  * @since 1.0
  */
 @GwtIncompatible
+@ElementTypesAreNonnullByDefault
 public final class CountingOutputStream extends FilterOutputStream {
 
   private long count;
diff --git a/guava/src/com/google/common/io/ElementTypesAreNonnullByDefault.java b/guava/src/com/google/common/io/ElementTypesAreNonnullByDefault.java
new file mode 100644
index 000000000000..48bc10f192a1
--- /dev/null
+++ b/guava/src/com/google/common/io/ElementTypesAreNonnullByDefault.java
@@ -0,0 +1,41 @@
+/*
+ * Copyright (C) 2021 The Guava Authors
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package com.google.common.io;
+
+import static java.lang.annotation.ElementType.FIELD;
+import static java.lang.annotation.ElementType.METHOD;
+import static java.lang.annotation.ElementType.PARAMETER;
+import static java.lang.annotation.ElementType.TYPE;
+import static java.lang.annotation.RetentionPolicy.RUNTIME;
+
+import com.google.common.annotations.GwtCompatible;
+import java.lang.annotation.Retention;
+import java.lang.annotation.Target;
+import javax.annotation.Nonnull;
+import javax.annotation.meta.TypeQualifierDefault;
+
+/**
+ * Marks all "top-level" types as non-null in a way that is recognized by Kotlin. Note that this
+ * unfortunately includes type-variable usages, so we also provide {@link ParametricNullness} to
+ * "undo" it as best we can.
+ */
+@GwtCompatible
+@Retention(RUNTIME)
+@Target(TYPE)
+@TypeQualifierDefault({FIELD, METHOD, PARAMETER})
+@Nonnull
+@interface ElementTypesAreNonnullByDefault {}
diff --git a/guava/src/com/google/common/io/FileBackedOutputStream.java b/guava/src/com/google/common/io/FileBackedOutputStream.java
index 51a6a04e2939..61a020e4e58e 100644
--- a/guava/src/com/google/common/io/FileBackedOutputStream.java
+++ b/guava/src/com/google/common/io/FileBackedOutputStream.java
@@ -14,6 +14,7 @@
 
 package com.google.common.io;
 
+import static java.util.Objects.requireNonNull;
 
 import com.google.common.annotations.Beta;
 import com.google.common.annotations.GwtIncompatible;
@@ -27,6 +28,7 @@
 import java.io.IOException;
 import java.io.InputStream;
 import java.io.OutputStream;
+import javax.annotation.CheckForNull;
 import org.checkerframework.checker.index.qual.IndexOrHigh;
 import org.checkerframework.checker.index.qual.LTLengthOf;
 import org.checkerframework.checker.index.qual.NonNegative;
@@ -54,20 +56,23 @@
  */
 @Beta
 @GwtIncompatible
+@ElementTypesAreNonnullByDefault
 public final class FileBackedOutputStream extends OutputStream {
   private final int fileThreshold;
   private final boolean resetOnFinalize;
   private final ByteSource source;
-  private final @Nullable File parentDirectory;
+  @CheckForNull private final File parentDirectory;
 
   @GuardedBy("this")
   private OutputStream out;
 
   @GuardedBy("this")
+  @CheckForNull
   private MemoryOutput memory;
 
   @GuardedBy("this")
-  private @Nullable File file;
+  @CheckForNull
+  private File file;
 
   /** ByteArrayOutputStream that exposes its internals. */
   private static class MemoryOutput extends ByteArrayOutputStream {
@@ -82,6 +87,7 @@ byte[] getBuffer() {
 
   /** Returns the file holding the data (possibly null). */
   @VisibleForTesting
+  @CheckForNull
   synchronized File getFile() {
     return file;
   }
@@ -109,7 +115,7 @@ public FileBackedOutputStream(int fileThreshold, boolean resetOnFinalize) {
   }
 
   private FileBackedOutputStream(
-      int fileThreshold, boolean resetOnFinalize, @Nullable File parentDirectory) {
+      int fileThreshold, boolean resetOnFinalize, @CheckForNull File parentDirectory) {
     this.fileThreshold = fileThreshold;
     this.resetOnFinalize = resetOnFinalize;
     this.parentDirectory = parentDirectory;
@@ -157,6 +163,8 @@ private synchronized InputStream openInputStream() throws IOException {
     if (file != null) {
       return new FileInputStream(file);
     } else {
+      // requireNonNull is safe because we always have either `file` or `memory`.
+      requireNonNull(memory);
       return new ByteArrayInputStream(memory.getBuffer(), 0, memory.getCount());
     }
   }
@@ -220,19 +228,24 @@ public synchronized void flush() throws IOException {
    */
   @GuardedBy("this")
   private void update(int len) throws IOException {
-    if (file == null && (memory.getCount() + len > fileThreshold)) {
+    if (memory != null && (memory.getCount() + len > fileThreshold)) {
       File temp = File.createTempFile("FileBackedOutputStream", null, parentDirectory);
       if (resetOnFinalize) {
         // Finalizers are not guaranteed to be called on system shutdown;
         // this is insurance.
         temp.deleteOnExit();
       }
-      FileOutputStream transfer = new FileOutputStream(temp);
-      transfer.write(memory.getBuffer(), 0, memory.getCount());
-      transfer.flush();
+      try {
+        FileOutputStream transfer = new FileOutputStream(temp);
+        transfer.write(memory.getBuffer(), 0, memory.getCount());
+        transfer.flush();
+        // We've successfully transferred the data; switch to writing to file
+        out = transfer;
+      } catch (IOException e) {
+        temp.delete();
+        throw e;
+      }
 
-      // We've successfully transferred the data; switch to writing to file
-      out = transfer;
       file = temp;
       memory = null;
     }
diff --git a/guava/src/com/google/common/io/FileWriteMode.java b/guava/src/com/google/common/io/FileWriteMode.java
index 2c69a2edb63b..86872d1badb2 100644
--- a/guava/src/com/google/common/io/FileWriteMode.java
+++ b/guava/src/com/google/common/io/FileWriteMode.java
@@ -23,6 +23,7 @@
  * @author Colin Decker
  */
 @GwtIncompatible
+@ElementTypesAreNonnullByDefault
 public enum FileWriteMode {
   /** Specifies that writes to the opened file should append to the end of the file. */
   APPEND
diff --git a/guava/src/com/google/common/io/Files.java b/guava/src/com/google/common/io/Files.java
index 805847e52293..046674c995af 100644
--- a/guava/src/com/google/common/io/Files.java
+++ b/guava/src/com/google/common/io/Files.java
@@ -32,6 +32,7 @@
 import com.google.common.hash.HashCode;
 import com.google.common.hash.HashFunction;
 import com.google.errorprone.annotations.CanIgnoreReturnValue;
+import com.google.errorprone.annotations.InlineMe;
 import java.io.BufferedReader;
 import java.io.BufferedWriter;
 import java.io.File;
@@ -52,8 +53,10 @@
 import java.util.Arrays;
 import java.util.Collections;
 import java.util.List;
+import javax.annotation.CheckForNull;
 import org.checkerframework.checker.index.qual.GTENegativeOne;
 import org.checkerframework.checker.index.qual.NonNegative;
+import org.checkerframework.checker.nullness.qual.Nullable;
 
 /**
  * Provides utility methods for working with {@linkplain File files}.
@@ -66,6 +69,7 @@
  * @since 1.0
  */
 @GwtIncompatible
+@ElementTypesAreNonnullByDefault
 public final class Files {
 
   /** Maximum loop count when creating temp directories. */
@@ -84,7 +88,6 @@ private Files() {}
    *     helpful predefined constants
    * @return the buffered reader
    */
-  @Beta
   public static BufferedReader newReader(File file, Charset charset) throws FileNotFoundException {
     checkNotNull(file);
     checkNotNull(charset);
@@ -103,7 +106,6 @@ public static BufferedReader newReader(File file, Charset charset) throws FileNo
    *     helpful predefined constants
    * @return the buffered writer
    */
-  @Beta
   public static BufferedWriter newWriter(File file, Charset charset) throws FileNotFoundException {
     checkNotNull(file);
     checkNotNull(charset);
@@ -234,7 +236,6 @@ public static CharSink asCharSink(File file, Charset charset, FileWriteMode... m
    *     (2^31 - 1)
    * @throws IOException if an I/O error occurs
    */
-  @Beta
   public static byte[] toByteArray(File file) throws IOException {
     return asByteSource(file).read();
   }
@@ -247,11 +248,12 @@ public static byte[] toByteArray(File file) throws IOException {
    *     helpful predefined constants
    * @return a string containing all the characters from the file
    * @throws IOException if an I/O error occurs
-   * @deprecated Prefer {@code asCharSource(file, charset).read()}. This method is scheduled to be
-   *     removed in October 2019.
+   * @deprecated Prefer {@code asCharSource(file, charset).read()}.
    */
-  @Beta
   @Deprecated
+  @InlineMe(
+      replacement = "Files.asCharSource(file, charset).read()",
+      imports = "com.google.common.io.Files")
   public static String toString(File file, Charset charset) throws IOException {
     return asCharSource(file, charset).read();
   }
@@ -266,7 +268,6 @@ public static String toString(File file, Charset charset) throws IOException {
    * @param to the destination file
    * @throws IOException if an I/O error occurs
    */
-  @Beta
   public static void write(byte[] from, File to) throws IOException {
     asByteSink(to).write(from);
   }
@@ -279,11 +280,12 @@ public static void write(byte[] from, File to) throws IOException {
    * @param charset the charset used to encode the output stream; see {@link StandardCharsets} for
    *     helpful predefined constants
    * @throws IOException if an I/O error occurs
-   * @deprecated Prefer {@code asCharSink(to, charset).write(from)}. This method is scheduled to be
-   *     removed in October 2019.
+   * @deprecated Prefer {@code asCharSink(to, charset).write(from)}.
    */
-  @Beta
   @Deprecated
+  @InlineMe(
+      replacement = "Files.asCharSink(to, charset).write(from)",
+      imports = "com.google.common.io.Files")
   public static void write(CharSequence from, File to, Charset charset) throws IOException {
     asCharSink(to, charset).write(from);
   }
@@ -298,7 +300,6 @@ public static void write(CharSequence from, File to, Charset charset) throws IOE
    * @param to the output stream
    * @throws IOException if an I/O error occurs
    */
-  @Beta
   public static void copy(File from, OutputStream to) throws IOException {
     asByteSource(from).copyTo(to);
   }
@@ -322,7 +323,6 @@ public static void copy(File from, OutputStream to) throws IOException {
    * @throws IOException if an I/O error occurs
    * @throws IllegalArgumentException if {@code from.equals(to)}
    */
-  @Beta
   public static void copy(File from, File to) throws IOException {
     checkArgument(!from.equals(to), "Source %s and destination %s must be different", from, to);
     asByteSource(from).copyTo(asByteSink(to));
@@ -336,11 +336,12 @@ public static void copy(File from, File to) throws IOException {
    *     helpful predefined constants
    * @param to the appendable object
    * @throws IOException if an I/O error occurs
-   * @deprecated Prefer {@code asCharSource(from, charset).copyTo(to)}. This method is scheduled to
-   *     be removed in October 2019.
+   * @deprecated Prefer {@code asCharSource(from, charset).copyTo(to)}.
    */
-  @Beta
   @Deprecated
+  @InlineMe(
+      replacement = "Files.asCharSource(from, charset).copyTo(to)",
+      imports = "com.google.common.io.Files")
   public
   static void copy(File from, Charset charset, Appendable to) throws IOException {
     asCharSource(from, charset).copyTo(to);
@@ -357,8 +358,10 @@ static void copy(File from, Charset charset, Appendable to) throws IOException {
    * @deprecated Prefer {@code asCharSink(to, charset, FileWriteMode.APPEND).write(from)}. This
    *     method is scheduled to be removed in October 2019.
    */
-  @Beta
   @Deprecated
+  @InlineMe(
+      replacement = "Files.asCharSink(to, charset, FileWriteMode.APPEND).write(from)",
+      imports = {"com.google.common.io.FileWriteMode", "com.google.common.io.Files"})
   public
   static void append(CharSequence from, File to, Charset charset) throws IOException {
     asCharSink(to, charset, FileWriteMode.APPEND).write(from);
@@ -369,7 +372,6 @@ static void append(CharSequence from, File to, Charset charset) throws IOExcepti
    *
    * @throws IOException if an I/O error occurs
    */
-  @Beta
   public static boolean equal(File file1, File file2) throws IOException {
     checkNotNull(file1);
     checkNotNull(file2);
@@ -451,7 +453,6 @@ public static File createTempDir() {
    * @param file the file to create or update
    * @throws IOException if an I/O error occurs
    */
-  @Beta
   @SuppressWarnings("GoodTime") // reading system time without TimeSource
   public static void touch(File file) throws IOException {
     checkNotNull(file);
@@ -469,7 +470,6 @@ public static void touch(File file) throws IOException {
    *     directories of the specified file could not be created.
    * @since 4.0
    */
-  @Beta
   public static void createParentDirs(File file) throws IOException {
     checkNotNull(file);
     File parent = file.getCanonicalFile().getParentFile();
@@ -500,7 +500,6 @@ public static void createParentDirs(File file) throws IOException {
    * @throws IOException if an I/O error occurs
    * @throws IllegalArgumentException if {@code from.equals(to)}
    */
-  @Beta
   public static void move(File from, File to) throws IOException {
     checkNotNull(from);
     checkNotNull(to);
@@ -526,11 +525,13 @@ public static void move(File from, File to) throws IOException {
    *     helpful predefined constants
    * @return the first line, or null if the file is empty
    * @throws IOException if an I/O error occurs
-   * @deprecated Prefer {@code asCharSource(file, charset).readFirstLine()}. This method is
-   *     scheduled to be removed in October 2019.
+   * @deprecated Prefer {@code asCharSource(file, charset).readFirstLine()}.
    */
-  @Beta
   @Deprecated
+  @InlineMe(
+      replacement = "Files.asCharSource(file, charset).readFirstLine()",
+      imports = "com.google.common.io.Files")
+  @CheckForNull
   public
   static String readFirstLine(File file, Charset charset) throws IOException {
     return asCharSource(file, charset).readFirstLine();
@@ -552,7 +553,6 @@ static String readFirstLine(File file, Charset charset) throws IOException {
    * @return a mutable {@link List} containing all the lines
    * @throws IOException if an I/O error occurs
    */
-  @Beta
   public static List<String> readLines(File file, Charset charset) throws IOException {
     // don't use asCharSource(file, charset).readLines() because that returns
     // an immutable list, which would change the behavior of this method
@@ -584,14 +584,17 @@ public List<String> getResult() {
    * @param callback the {@link LineProcessor} to use to handle the lines
    * @return the output of processing the lines
    * @throws IOException if an I/O error occurs
-   * @deprecated Prefer {@code asCharSource(file, charset).readLines(callback)}. This method is
-   *     scheduled to be removed in October 2019.
+   * @deprecated Prefer {@code asCharSource(file, charset).readLines(callback)}.
    */
-  @Beta
   @Deprecated
+  @InlineMe(
+      replacement = "Files.asCharSource(file, charset).readLines(callback)",
+      imports = "com.google.common.io.Files")
   @CanIgnoreReturnValue // some processors won't return a useful result
+  @ParametricNullness
   public
-  static <T> T readLines(File file, Charset charset, LineProcessor<T> callback) throws IOException {
+  static <T extends @Nullable Object> T readLines(
+      File file, Charset charset, LineProcessor<T> callback) throws IOException {
     return asCharSource(file, charset).readLines(callback);
   }
 
@@ -604,14 +607,17 @@ static <T> T readLines(File file, Charset charset, LineProcessor<T> callback) th
    * @param processor the object to which the bytes of the file are passed.
    * @return the result of the byte processor
    * @throws IOException if an I/O error occurs
-   * @deprecated Prefer {@code asByteSource(file).read(processor)}. This method is scheduled to be
-   *     removed in October 2019.
+   * @deprecated Prefer {@code asByteSource(file).read(processor)}.
    */
-  @Beta
   @Deprecated
+  @InlineMe(
+      replacement = "Files.asByteSource(file).read(processor)",
+      imports = "com.google.common.io.Files")
   @CanIgnoreReturnValue // some processors won't return a useful result
+  @ParametricNullness
   public
-  static <T> T readBytes(File file, ByteProcessor<T> processor) throws IOException {
+  static <T extends @Nullable Object> T readBytes(File file, ByteProcessor<T> processor)
+      throws IOException {
     return asByteSource(file).read(processor);
   }
 
@@ -623,11 +629,12 @@ static <T> T readBytes(File file, ByteProcessor<T> processor) throws IOException
    * @return the {@link HashCode} of all of the bytes in the file
    * @throws IOException if an I/O error occurs
    * @since 12.0
-   * @deprecated Prefer {@code asByteSource(file).hash(hashFunction)}. This method is scheduled to
-   *     be removed in October 2019.
+   * @deprecated Prefer {@code asByteSource(file).hash(hashFunction)}.
    */
-  @Beta
   @Deprecated
+  @InlineMe(
+      replacement = "Files.asByteSource(file).hash(hashFunction)",
+      imports = "com.google.common.io.Files")
   public
   static HashCode hash(File file, HashFunction hashFunction) throws IOException {
     return asByteSource(file).hash(hashFunction);
@@ -648,7 +655,6 @@ static HashCode hash(File file, HashFunction hashFunction) throws IOException {
    * @see FileChannel#map(MapMode, long, long)
    * @since 2.0
    */
-  @Beta
   public static MappedByteBuffer map(File file) throws IOException {
     checkNotNull(file);
     return map(file, MapMode.READ_ONLY);
@@ -671,7 +677,6 @@ public static MappedByteBuffer map(File file) throws IOException {
    * @see FileChannel#map(MapMode, long, long)
    * @since 2.0
    */
-  @Beta
   public static MappedByteBuffer map(File file, MapMode mode) throws IOException {
     return mapInternal(file, mode, -1);
   }
@@ -695,7 +700,6 @@ public static MappedByteBuffer map(File file, MapMode mode) throws IOException {
    * @see FileChannel#map(MapMode, long, long)
    * @since 2.0
    */
-  @Beta
   public static MappedByteBuffer map(File file, MapMode mode, @NonNegative long size) throws IOException {
     checkArgument(size >= 0, "size (%s) may not be negative", size);
     return mapInternal(file, mode, size);
@@ -739,7 +743,6 @@ private static MappedByteBuffer mapInternal(File file, MapMode mode, @GTENegativ
    *
    * @since 11.0
    */
-  @Beta
   public static String simplifyPath(String pathname) {
     checkNotNull(pathname);
     if (pathname.length() == 0) {
@@ -800,7 +803,6 @@ public static String simplifyPath(String pathname) {
    *
    * @since 11.0
    */
-  @Beta
   public static String getFileExtension(String fullName) {
     checkNotNull(fullName);
     String fileName = new File(fullName).getName();
@@ -818,7 +820,6 @@ public static String getFileExtension(String fullName) {
    * @return The file name without its path or extension.
    * @since 14.0
    */
-  @Beta
   public static String getNameWithoutExtension(String file) {
     checkNotNull(file);
     String fileName = new File(file).getName();
@@ -874,7 +875,6 @@ public Iterable<File> successors(File file) {
    *
    * @since 15.0
    */
-  @Beta
   public static Predicate<File> isDirectory() {
     return FilePredicate.IS_DIRECTORY;
   }
@@ -884,7 +884,6 @@ public static Predicate<File> isDirectory() {
    *
    * @since 15.0
    */
-  @Beta
   public static Predicate<File> isFile() {
     return FilePredicate.IS_FILE;
   }
diff --git a/guava/src/com/google/common/io/Flushables.java b/guava/src/com/google/common/io/Flushables.java
index 9b1d6a096136..1f795a24ab24 100644
--- a/guava/src/com/google/common/io/Flushables.java
+++ b/guava/src/com/google/common/io/Flushables.java
@@ -29,6 +29,7 @@
  */
 @Beta
 @GwtIncompatible
+@ElementTypesAreNonnullByDefault
 public final class Flushables {
   private static final Logger logger = Logger.getLogger(Flushables.class.getName());
 
diff --git a/guava/src/com/google/common/io/InsecureRecursiveDeleteException.java b/guava/src/com/google/common/io/InsecureRecursiveDeleteException.java
index 7d0780571511..414093606b51 100644
--- a/guava/src/com/google/common/io/InsecureRecursiveDeleteException.java
+++ b/guava/src/com/google/common/io/InsecureRecursiveDeleteException.java
@@ -21,7 +21,7 @@
 import com.google.j2objc.annotations.J2ObjCIncompatible;
 import java.nio.file.FileSystemException;
 import java.nio.file.SecureDirectoryStream;
-import org.checkerframework.checker.nullness.qual.Nullable;
+import javax.annotation.CheckForNull;
 
 /**
  * Exception indicating that a recursive delete can't be performed because the file system does not
@@ -38,9 +38,10 @@
 @Beta
 @GwtIncompatible
 @J2ObjCIncompatible // java.nio.file
+@ElementTypesAreNonnullByDefault
 public final class InsecureRecursiveDeleteException extends FileSystemException {
 
-  public InsecureRecursiveDeleteException(@Nullable String file) {
+  public InsecureRecursiveDeleteException(@CheckForNull String file) {
     super(file, null, "unable to guarantee security of recursive delete");
   }
 }
diff --git a/guava/src/com/google/common/io/Java8Compatibility.java b/guava/src/com/google/common/io/Java8Compatibility.java
index 62b5c2ea5b7f..705d97b4dfa5 100644
--- a/guava/src/com/google/common/io/Java8Compatibility.java
+++ b/guava/src/com/google/common/io/Java8Compatibility.java
@@ -22,6 +22,7 @@
  * https://github.com/google/guava/issues/3990
  */
 @GwtIncompatible
+@ElementTypesAreNonnullByDefault
 final class Java8Compatibility {
   static void clear(Buffer b) {
     b.clear();
@@ -35,9 +36,17 @@ static void limit(Buffer b, int limit) {
     b.limit(limit);
   }
 
+  static void mark(Buffer b) {
+    b.mark();
+  }
+
   static void position(Buffer b, int position) {
     b.position(position);
   }
 
+  static void reset(Buffer b) {
+    b.reset();
+  }
+
   private Java8Compatibility() {}
 }
diff --git a/guava/src/com/google/common/io/LineBuffer.java b/guava/src/com/google/common/io/LineBuffer.java
index de578c0c7261..502273d3bab7 100644
--- a/guava/src/com/google/common/io/LineBuffer.java
+++ b/guava/src/com/google/common/io/LineBuffer.java
@@ -33,6 +33,7 @@
  * @since 1.0
  */
 @GwtIncompatible
+@ElementTypesAreNonnullByDefault
 abstract class LineBuffer {
   /** Holds partial line contents. */
   private StringBuilder line = new StringBuilder();
@@ -49,11 +50,15 @@ abstract class LineBuffer {
    * @throws IOException if an I/O error occurs
    * @see #finish
    */
-  @SuppressWarnings({"array.access.unsafe.high", "argument.type.incompatible", "assignment.type.incompatible"}) /*
-  #1. The first if block doesn't get executed if pos = cbuf.length.
-  #2. If pos = cbuf.length, the first if block doesn't get executed.
-  #3 and #4. pos - start is within bounds because the for loop ends at off + len, which is the precondition.
-  #5. off + len - start is valid because off + len cannot exceed the limit of the buffer. */
+  @SuppressWarnings({
+      "index:argument",
+      "index:assignment",
+      "upperbound:array.access.unsafe.high",
+      })
+      // #1. The first if block doesn't get executed if pos = cbuf.length.
+      // #2. If pos = cbuf.length, the first if block doesn't get executed.
+      // #3 and #4. pos - start is within bounds because the for loop ends at off + len, which is the precondition.
+      // #5. off + len - start is valid because off + len cannot exceed the limit of the buffer.
   protected void add(char[] cbuf, @IndexOrHigh("#1") int off, @NonNegative @LTLengthOf(value = "#1", offset = "#2 - 1") int len) throws IOException {
     int pos = off;
     if (sawReturn && len > 0) {
diff --git a/guava/src/com/google/common/io/LineProcessor.java b/guava/src/com/google/common/io/LineProcessor.java
index 65ded53a4701..e28bebcc5f2b 100644
--- a/guava/src/com/google/common/io/LineProcessor.java
+++ b/guava/src/com/google/common/io/LineProcessor.java
@@ -18,6 +18,7 @@
 import com.google.common.annotations.GwtIncompatible;
 import com.google.errorprone.annotations.CanIgnoreReturnValue;
 import java.io.IOException;
+import org.checkerframework.checker.nullness.qual.Nullable;
 
 /**
  * A callback to be used with the streaming {@code readLines} methods.
@@ -30,7 +31,8 @@
  */
 @Beta
 @GwtIncompatible
-public interface LineProcessor<T> {
+@ElementTypesAreNonnullByDefault
+public interface LineProcessor<T extends @Nullable Object> {
 
   /**
    * This method will be called once for each line.
@@ -42,5 +44,6 @@ public interface LineProcessor<T> {
   boolean processLine(String line) throws IOException;
 
   /** Return the result of processing all the lines. */
+  @ParametricNullness
   T getResult();
 }
diff --git a/guava/src/com/google/common/io/LineReader.java b/guava/src/com/google/common/io/LineReader.java
index 67d17884eebb..acd582ebe127 100644
--- a/guava/src/com/google/common/io/LineReader.java
+++ b/guava/src/com/google/common/io/LineReader.java
@@ -25,7 +25,7 @@
 import java.nio.CharBuffer;
 import java.util.ArrayDeque;
 import java.util.Queue;
-import org.checkerframework.checker.nullness.qual.Nullable;
+import javax.annotation.CheckForNull;
 
 /**
  * A class for reading lines of text. Provides the same functionality as {@link
@@ -37,9 +37,10 @@
  */
 @Beta
 @GwtIncompatible
+@ElementTypesAreNonnullByDefault
 public final class LineReader {
   private final Readable readable;
-  private final @Nullable Reader reader;
+  @CheckForNull private final Reader reader;
   private final CharBuffer cbuf = createBuffer();
   private final char[] buf = cbuf.array();
 
@@ -68,7 +69,8 @@ public LineReader(Readable readable) {
    * @throws IOException if an I/O error occurs
    */
   @CanIgnoreReturnValue // to skip a line
-  @SuppressWarnings("argument.type.incompatible") // buf is the array representation of cbuf, so the call to add(char[], int, int) is safe.
+  @SuppressWarnings("index:argument") // buf is the array representation of cbuf, so the call to add(char[], int, int) is safe.
+  @CheckForNull
   public String readLine() throws IOException {
     while (lines.peek() == null) {
       Java8Compatibility.clear(cbuf);
diff --git a/guava/src/com/google/common/io/LittleEndianDataInputStream.java b/guava/src/com/google/common/io/LittleEndianDataInputStream.java
index 9d5c12e9c810..361b409c1e21 100644
--- a/guava/src/com/google/common/io/LittleEndianDataInputStream.java
+++ b/guava/src/com/google/common/io/LittleEndianDataInputStream.java
@@ -44,6 +44,7 @@
  */
 @Beta
 @GwtIncompatible
+@ElementTypesAreNonnullByDefault
 public final class LittleEndianDataInputStream extends FilterInputStream implements DataInput {
 
   /**
@@ -99,7 +100,7 @@ public void readFully(byte[] b, @IndexOrHigh("#1") int off, @NonNegative @LTLeng
    */
   @CanIgnoreReturnValue // to skip some bytes
   @Override
-  @SuppressWarnings("return.type.incompatible") // The integer returned has its first bit equal to 0.
+  @SuppressWarnings("index:return") // The integer returned has its first bit equal to 0.
   public @NonNegative int readUnsignedShort() throws IOException {
     byte b1 = readAndCheckByte();
     byte b2 = readAndCheckByte();
diff --git a/guava/src/com/google/common/io/LittleEndianDataOutputStream.java b/guava/src/com/google/common/io/LittleEndianDataOutputStream.java
index 27dc6a5808cd..f913fa2592b9 100644
--- a/guava/src/com/google/common/io/LittleEndianDataOutputStream.java
+++ b/guava/src/com/google/common/io/LittleEndianDataOutputStream.java
@@ -40,6 +40,7 @@
  */
 @Beta
 @GwtIncompatible
+@ElementTypesAreNonnullByDefault
 public final class LittleEndianDataOutputStream extends FilterOutputStream implements DataOutput {
 
   /**
diff --git a/guava/src/com/google/common/io/MoreFiles.java b/guava/src/com/google/common/io/MoreFiles.java
index 8bc810f11fa8..d52e0b8301e6 100644
--- a/guava/src/com/google/common/io/MoreFiles.java
+++ b/guava/src/com/google/common/io/MoreFiles.java
@@ -17,7 +17,9 @@
 package com.google.common.io;
 
 import static com.google.common.base.Preconditions.checkNotNull;
+import static com.google.common.collect.Iterables.getOnlyElement;
 import static java.nio.file.LinkOption.NOFOLLOW_LINKS;
+import static java.util.Objects.requireNonNull;
 
 import com.google.common.annotations.Beta;
 import com.google.common.annotations.GwtIncompatible;
@@ -53,6 +55,7 @@
 import java.util.Arrays;
 import java.util.Collection;
 import java.util.stream.Stream;
+import javax.annotation.CheckForNull;
 import org.checkerframework.checker.index.qual.NonNegative;
 import org.checkerframework.checker.nullness.qual.Nullable;
 
@@ -69,6 +72,7 @@
 @Beta
 @GwtIncompatible
 @J2ObjCIncompatible // java.nio.file
+@ElementTypesAreNonnullByDefault
 public final class MoreFiles {
 
   private MoreFiles() {}
@@ -533,7 +537,13 @@ public static void deleteRecursively(Path path, RecursiveDeleteOption... options
         if (parent instanceof SecureDirectoryStream) {
           sdsSupported = true;
           exceptions =
-              deleteRecursivelySecure((SecureDirectoryStream<Path>) parent, path.getFileName());
+              deleteRecursivelySecure(
+                  (SecureDirectoryStream<Path>) parent,
+                  /*
+                   * requireNonNull is safe because paths have file names when they have parents,
+                   * and we checked for a parent at the beginning of the method.
+                   */
+                  requireNonNull(path.getFileName()));
         }
       }
 
@@ -613,7 +623,8 @@ public static void deleteDirectoryContents(Path path, RecursiveDeleteOption... o
    * Secure recursive delete using {@code SecureDirectoryStream}. Returns a collection of exceptions
    * that occurred or null if no exceptions were thrown.
    */
-  private static @Nullable Collection<IOException> deleteRecursivelySecure(
+  @CheckForNull
+  private static Collection<IOException> deleteRecursivelySecure(
       SecureDirectoryStream<Path> dir, Path path) {
     Collection<IOException> exceptions = null;
     try {
@@ -641,7 +652,8 @@ public static void deleteDirectoryContents(Path path, RecursiveDeleteOption... o
    * Secure method for deleting the contents of a directory using {@code SecureDirectoryStream}.
    * Returns a collection of exceptions that occurred or null if no exceptions were thrown.
    */
-  private static @Nullable Collection<IOException> deleteDirectoryContentsSecure(
+  @CheckForNull
+  private static Collection<IOException> deleteDirectoryContentsSecure(
       SecureDirectoryStream<Path> dir) {
     Collection<IOException> exceptions = null;
     try {
@@ -659,7 +671,8 @@ public static void deleteDirectoryContents(Path path, RecursiveDeleteOption... o
    * Insecure recursive delete for file systems that don't support {@code SecureDirectoryStream}.
    * Returns a collection of exceptions that occurred or null if no exceptions were thrown.
    */
-  private static @Nullable Collection<IOException> deleteRecursivelyInsecure(Path path) {
+  @CheckForNull
+  private static Collection<IOException> deleteRecursivelyInsecure(Path path) {
     Collection<IOException> exceptions = null;
     try {
       if (Files.isDirectory(path, NOFOLLOW_LINKS)) {
@@ -685,7 +698,8 @@ public static void deleteDirectoryContents(Path path, RecursiveDeleteOption... o
    * support {@code SecureDirectoryStream}. Returns a collection of exceptions that occurred or null
    * if no exceptions were thrown.
    */
-  private static @Nullable Collection<IOException> deleteDirectoryContentsInsecure(
+  @CheckForNull
+  private static Collection<IOException> deleteDirectoryContentsInsecure(
       DirectoryStream<Path> dir) {
     Collection<IOException> exceptions = null;
     try {
@@ -704,7 +718,8 @@ public static void deleteDirectoryContents(Path path, RecursiveDeleteOption... o
    * path, this is simple. Otherwise, we need to do some trickier things. Returns null if the path
    * is a root or is the empty path.
    */
-  private static @Nullable Path getParentPath(Path path) {
+  @CheckForNull
+  private static Path getParentPath(Path path) {
     Path parent = path.getParent();
 
     // Paths that have a parent:
@@ -750,7 +765,7 @@ private static void checkAllowsInsecure(Path path, RecursiveDeleteOption[] optio
    * the collection.
    */
   private static Collection<IOException> addException(
-      @Nullable Collection<IOException> exceptions, IOException e) {
+      @CheckForNull Collection<IOException> exceptions, IOException e) {
     if (exceptions == null) {
       exceptions = new ArrayList<>(); // don't need Set semantics
     }
@@ -763,8 +778,10 @@ private static Collection<IOException> addException(
    * null, the other collection is returned. Otherwise, the elements of {@code other} are added to
    * {@code exceptions} and {@code exceptions} is returned.
    */
-  private static @Nullable Collection<IOException> concat(
-      @Nullable Collection<IOException> exceptions, @Nullable Collection<IOException> other) {
+  @CheckForNull
+  private static Collection<IOException> concat(
+      @CheckForNull Collection<IOException> exceptions,
+      @CheckForNull Collection<IOException> other) {
     if (exceptions == null) {
       return other;
     } else if (other != null) {
@@ -774,11 +791,19 @@ private static Collection<IOException> addException(
   }
 
   /**
-   * Throws an exception indicating that one or more files couldn't be deleted. The thrown exception
-   * contains all the exceptions in the given collection as suppressed exceptions.
+   * Throws an exception indicating that one or more files couldn't be deleted when deleting {@code
+   * path} or its contents.
+   *
+   * <p>If there is only one exception in the collection, and it is a {@link NoSuchFileException}
+   * thrown because {@code path} itself didn't exist, then throws that exception. Otherwise, the
+   * thrown exception contains all the exceptions in the given collection as suppressed exceptions.
    */
   private static void throwDeleteFailed(Path path, Collection<IOException> exceptions)
       throws FileSystemException {
+    NoSuchFileException pathNotFound = pathNotFound(path, exceptions);
+    if (pathNotFound != null) {
+      throw pathNotFound;
+    }
     // TODO(cgdecker): Should there be a custom exception type for this?
     // Also, should we try to include the Path of each file we may have failed to delete rather
     // than just the exceptions that occurred?
@@ -792,4 +817,53 @@ private static void throwDeleteFailed(Path path, Collection<IOException> excepti
     }
     throw deleteFailed;
   }
+
+  @CheckForNull
+  private static NoSuchFileException pathNotFound(Path path, Collection<IOException> exceptions) {
+    if (exceptions.size() != 1) {
+      return null;
+    }
+    IOException exception = getOnlyElement(exceptions);
+    if (!(exception instanceof NoSuchFileException)) {
+      return null;
+    }
+    NoSuchFileException noSuchFileException = (NoSuchFileException) exception;
+    String exceptionFile = noSuchFileException.getFile();
+    if (exceptionFile == null) {
+      /*
+       * It's not clear whether this happens in practice, especially with the filesystem
+       * implementations that are built into java.nio.
+       */
+      return null;
+    }
+    Path parentPath = getParentPath(path);
+    if (parentPath == null) {
+      /*
+       * This is probably impossible:
+       *
+       * - In deleteRecursively, we require the path argument to have a parent.
+       *
+       * - In deleteDirectoryContents, the path argument may have no parent. Fortunately, all the
+       *   *other* paths we process will be descendants of that. That leaves only the original path
+       *   argument for us to consider. And the only place we call pathNotFound is from
+       *   throwDeleteFailed, and the other place that we call throwDeleteFailed inside
+       *   deleteDirectoryContents is when an exception is thrown during the recursive steps. Any
+       *   failure during the initial lookup of the path argument itself is rethrown directly. So
+       *   any exception that we're seeing here is from a descendant, which naturally has a parent.
+       *   I think.
+       *
+       * Still, if this can happen somehow (a weird filesystem implementation that lets callers
+       * change its working directly concurrently with a call to deleteDirectoryContents?), it makes
+       * more sense for us to fall back to a generic FileSystemException (by returning null here)
+       * than to dereference parentPath and end up producing NullPointerException.
+       */
+      return null;
+    }
+    // requireNonNull is safe because paths have file names when they have parents.
+    Path pathResolvedFromParent = parentPath.resolve(requireNonNull(path.getFileName()));
+    if (exceptionFile.equals(pathResolvedFromParent.toString())) {
+      return noSuchFileException;
+    }
+    return null;
+  }
 }
diff --git a/guava/src/com/google/common/io/MultiInputStream.java b/guava/src/com/google/common/io/MultiInputStream.java
index 11890f5f7cc7..ee684ef260d0 100644
--- a/guava/src/com/google/common/io/MultiInputStream.java
+++ b/guava/src/com/google/common/io/MultiInputStream.java
@@ -20,6 +20,7 @@
 import java.io.IOException;
 import java.io.InputStream;
 import java.util.Iterator;
+import javax.annotation.CheckForNull;
 import org.checkerframework.checker.index.qual.GTENegativeOne;
 import org.checkerframework.checker.index.qual.IndexOrHigh;
 import org.checkerframework.checker.index.qual.LTEqLengthOf;
@@ -35,10 +36,11 @@
  * @since 1.0
  */
 @GwtIncompatible
+@ElementTypesAreNonnullByDefault
 final class MultiInputStream extends InputStream {
 
   private Iterator<? extends ByteSource> it;
-  private @Nullable InputStream in;
+  @CheckForNull private InputStream in;
 
   /**
    * Creates a new instance.
@@ -95,7 +97,8 @@ public boolean markSupported() {
   }
 
   @Override
-  public @GTENegativeOne @LTEqLengthOf("#1") int read(byte @Nullable [] b, @IndexOrHigh("#1") int off, @NonNegative @LTLengthOf(value = "#1", offset = "#2 - 1") int len) throws IOException {
+  public @GTENegativeOne @LTEqLengthOf("#1") int read(byte [] b, @IndexOrHigh("#1") int off, @NonNegative @LTLengthOf(value = "#1", offset = "#2 - 1") int len) throws IOException {
+    checkNotNull(b);
     while (in != null) {
       int result = in.read(b, off, len);
       if (result != -1) {
diff --git a/guava/src/com/google/common/io/MultiReader.java b/guava/src/com/google/common/io/MultiReader.java
index 508126e0291a..d74b801c19eb 100644
--- a/guava/src/com/google/common/io/MultiReader.java
+++ b/guava/src/com/google/common/io/MultiReader.java
@@ -14,11 +14,14 @@
 
 package com.google.common.io;
 
+import static com.google.common.base.Preconditions.checkNotNull;
+
 import com.google.common.annotations.GwtIncompatible;
 import com.google.common.base.Preconditions;
 import java.io.IOException;
 import java.io.Reader;
 import java.util.Iterator;
+import javax.annotation.CheckForNull;
 import org.checkerframework.checker.index.qual.GTENegativeOne;
 import org.checkerframework.checker.index.qual.IndexOrHigh;
 import org.checkerframework.checker.index.qual.LTEqLengthOf;
@@ -33,9 +36,10 @@
  * @since 1.0
  */
 @GwtIncompatible
+@ElementTypesAreNonnullByDefault
 class MultiReader extends Reader {
   private final Iterator<? extends CharSource> it;
-  private @Nullable Reader current;
+  @CheckForNull private Reader current;
 
   MultiReader(Iterator<? extends CharSource> readers) throws IOException {
     this.it = readers;
@@ -51,7 +55,8 @@ private void advance() throws IOException {
   }
 
   @Override
-  public @GTENegativeOne @LTEqLengthOf("#1") int read(char @Nullable [] cbuf, @IndexOrHigh("#1") int off, @NonNegative @LTLengthOf(value = "#1", offset = "#2 - 1") int len) throws IOException {
+  public @GTENegativeOne @LTEqLengthOf("#1") int read(char [] cbuf, @IndexOrHigh("#1") int off, @NonNegative @LTLengthOf(value = "#1", offset = "#2 - 1") int len) throws IOException {
+    checkNotNull(cbuf);
     if (current == null) {
       return -1;
     }
diff --git a/guava/src/com/google/common/io/ParametricNullness.java b/guava/src/com/google/common/io/ParametricNullness.java
new file mode 100644
index 000000000000..98da765852b6
--- /dev/null
+++ b/guava/src/com/google/common/io/ParametricNullness.java
@@ -0,0 +1,52 @@
+/*
+ * Copyright (C) 2021 The Guava Authors
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package com.google.common.io;
+
+import static java.lang.annotation.ElementType.FIELD;
+import static java.lang.annotation.ElementType.METHOD;
+import static java.lang.annotation.ElementType.PARAMETER;
+import static java.lang.annotation.RetentionPolicy.RUNTIME;
+
+import com.google.common.annotations.GwtCompatible;
+import java.lang.annotation.Retention;
+import java.lang.annotation.Target;
+
+/**
+ * Marks a "top-level" type-variable usage as the closest we can get to "non-nullable when
+ * non-nullable; nullable when nullable" (like the Android <a
+ * href="https://android.googlesource.com/platform/libcore/+/master/luni/src/main/java/libcore/util/NullFromTypeParam.java">{@code
+ * NullFromTypeParam}</a>).
+ *
+ * <p>Consumers of this annotation include:
+ *
+ * <ul>
+ *   <li>Kotlin, for which it makes the type-variable usage (a) a Kotlin platform type when the type
+ *       argument is non-nullable and (b) nullable when the type argument is nullable. We use this
+ *       to "undo" {@link ElementTypesAreNonnullByDefault}.
+ *   <li><a href="https://developers.google.com/j2objc">J2ObjC</a>
+ *   <li>{@code NullPointerTester}, at least in the Android backport (where the type-use annotations
+ *       {@code NullPointerTester} would need are not available) and in case of <a
+ *       href="https://bugs.openjdk.java.net/browse/JDK-8202469">JDK-8202469</a>
+ * </ul>
+ *
+ */
+@GwtCompatible
+@Retention(RUNTIME)
+@Target({FIELD, METHOD, PARAMETER})
+@javax.annotation.meta.TypeQualifierNickname
+@javax.annotation.Nonnull(when = javax.annotation.meta.When.UNKNOWN)
+@interface ParametricNullness {}
diff --git a/guava/src/com/google/common/io/PatternFilenameFilter.java b/guava/src/com/google/common/io/PatternFilenameFilter.java
index 4058e7d29602..3cb2371e2fd4 100644
--- a/guava/src/com/google/common/io/PatternFilenameFilter.java
+++ b/guava/src/com/google/common/io/PatternFilenameFilter.java
@@ -21,7 +21,6 @@
 import java.io.FilenameFilter;
 import java.util.regex.Pattern;
 import java.util.regex.PatternSyntaxException;
-import org.checkerframework.checker.nullness.qual.Nullable;
 
 /**
  * File name filter that only accepts files matching a regular expression. This class is thread-safe
@@ -32,6 +31,7 @@
  */
 @Beta
 @GwtIncompatible
+@ElementTypesAreNonnullByDefault
 public final class PatternFilenameFilter implements FilenameFilter {
 
   private final Pattern pattern;
@@ -55,8 +55,21 @@ public PatternFilenameFilter(Pattern pattern) {
     this.pattern = Preconditions.checkNotNull(pattern);
   }
 
+  /*
+   * Our implementation works fine with a null `dir`. However, there's nothing in the documentation
+   * of the supertype that suggests that implementations are expected to tolerate null. That said, I
+   * see calls in Google code that pass a null `dir` to a FilenameFilter.... So let's declare the
+   * parameter as non-nullable (since passing null to a FilenameFilter is unsafe in general), but if
+   * someone still manages to pass null, let's continue to have the method work.
+   *
+   * (PatternFilenameFilter is of course one of those classes that shouldn't be a publicly visible
+   * class to begin with but rather something returned from a static factory method whose declared
+   * return type is plain FilenameFilter. If we made such a change, then the annotation we choose
+   * here would have no significance to end users, who would be forced to conform to the signature
+   * used in FilenameFilter.)
+   */
   @Override
-  public boolean accept(@Nullable File dir, String fileName) {
+  public boolean accept(File dir, String fileName) {
     return pattern.matcher(fileName).matches();
   }
 }
diff --git a/guava/src/com/google/common/io/ReaderInputStream.java b/guava/src/com/google/common/io/ReaderInputStream.java
index 2d7fb4577fbc..89415deffb76 100644
--- a/guava/src/com/google/common/io/ReaderInputStream.java
+++ b/guava/src/com/google/common/io/ReaderInputStream.java
@@ -49,6 +49,7 @@
  * @author Chris Nokleberg
  */
 @GwtIncompatible
+@ElementTypesAreNonnullByDefault
 final class ReaderInputStream extends InputStream {
   private final Reader reader;
   private final CharsetEncoder encoder;
@@ -127,7 +128,7 @@ public void close() throws IOException {
   // TODO(chrisn): Consider trying to encode/flush directly to the argument byte
   // buffer when possible.
   @Override
-  @SuppressWarnings({"argument.type.incompatible", "return.type.incompatible"}) /*
+  @SuppressWarnings({"index:argument", "index:return"}) /*
   #1. The call to drain is safe because both off and len have been checked before and totalBytesRead can't exceed len, because that is the stopping condition.
   #2. The return type is safe because the while loop stops at len index, which has been previously checked */
   public @GTENegativeOne @LTEqLengthOf("#1") int read(byte[] b, @IndexOrHigh("#1") int off, @NonNegative @LTLengthOf(value = "#1", offset = "#2 - 1") int len) throws IOException {
@@ -224,7 +225,7 @@ private void readMoreChars() throws IOException {
 
     // (1) Read more characters into free space at end of array.
     int limit = charBuffer.limit();
-    @SuppressWarnings("argument.type.incompatible") /* limit is within bounds because it was verified in constructor
+    @SuppressWarnings("index:argument") /* limit is within bounds because it was verified in constructor
     and availableCapacity returns the difference between the capacity and the limit */
     int numChars = reader.read(charBuffer.array(), limit, availableCapacity(charBuffer));
     if (numChars == -1) {
diff --git a/guava/src/com/google/common/io/RecursiveDeleteOption.java b/guava/src/com/google/common/io/RecursiveDeleteOption.java
index 20ec7d280e70..1bb27a16b2df 100644
--- a/guava/src/com/google/common/io/RecursiveDeleteOption.java
+++ b/guava/src/com/google/common/io/RecursiveDeleteOption.java
@@ -31,6 +31,7 @@
 @Beta
 @GwtIncompatible
 @J2ObjCIncompatible // java.nio.file
+@ElementTypesAreNonnullByDefault
 public enum RecursiveDeleteOption {
   /**
    * Specifies that the recursive delete should not throw an exception when it can't be guaranteed
diff --git a/guava/src/com/google/common/io/Resources.java b/guava/src/com/google/common/io/Resources.java
index d64bf3d51d65..d1e37070a91c 100644
--- a/guava/src/com/google/common/io/Resources.java
+++ b/guava/src/com/google/common/io/Resources.java
@@ -17,7 +17,6 @@
 import static com.google.common.base.Preconditions.checkArgument;
 import static com.google.common.base.Preconditions.checkNotNull;
 
-import com.google.common.annotations.Beta;
 import com.google.common.annotations.GwtIncompatible;
 import com.google.common.base.Charsets;
 import com.google.common.base.MoreObjects;
@@ -29,21 +28,20 @@
 import java.net.URL;
 import java.nio.charset.Charset;
 import java.util.List;
+import org.checkerframework.checker.nullness.qual.Nullable;
 
 /**
  * Provides utility methods for working with resources in the classpath. Note that even though these
  * methods use {@link URL} parameters, they are usually not appropriate for HTTP or other
  * non-classpath resources.
  *
- * <p>All method parameters must be non-null unless documented otherwise.
- *
  * @author Chris Nokleberg
  * @author Ben Yu
  * @author Colin Decker
  * @since 1.0
  */
-@Beta
 @GwtIncompatible
+@ElementTypesAreNonnullByDefault
 public final class Resources {
   private Resources() {}
 
@@ -121,8 +119,9 @@ public static String toString(URL url, Charset charset) throws IOException {
    * @throws IOException if an I/O error occurs
    */
   @CanIgnoreReturnValue // some processors won't return a useful result
-  public static <T> T readLines(URL url, Charset charset, LineProcessor<T> callback)
-      throws IOException {
+  @ParametricNullness
+  public static <T extends @Nullable Object> T readLines(
+      URL url, Charset charset, LineProcessor<T> callback) throws IOException {
     return asCharSource(url, charset).readLines(callback);
   }
 
diff --git a/guava/src/com/google/common/math/BigDecimalMath.java b/guava/src/com/google/common/math/BigDecimalMath.java
index b5c23f8dd993..33a55d356312 100644
--- a/guava/src/com/google/common/math/BigDecimalMath.java
+++ b/guava/src/com/google/common/math/BigDecimalMath.java
@@ -25,6 +25,7 @@
  * @since 30.0
  */
 @GwtIncompatible
+@ElementTypesAreNonnullByDefault
 public class BigDecimalMath {
   private BigDecimalMath() {}
 
diff --git a/guava/src/com/google/common/math/BigIntegerMath.java b/guava/src/com/google/common/math/BigIntegerMath.java
index 8540fe95078a..c4d0823a9181 100644
--- a/guava/src/com/google/common/math/BigIntegerMath.java
+++ b/guava/src/com/google/common/math/BigIntegerMath.java
@@ -52,6 +52,7 @@
  * @since 11.0
  */
 @GwtCompatible(emulated = true)
+@ElementTypesAreNonnullByDefault
 public final class BigIntegerMath {
   /**
    * Returns the smallest power of two greater than or equal to {@code x}. This is equivalent to
@@ -150,13 +151,13 @@ public static int log2(BigInteger x, RoundingMode mode) {
    *     is not a power of ten
    */
   @GwtIncompatible // TODO
-  @SuppressWarnings({"fallthrough","lowerbound:argument.type.incompatible"// x fits in a long, then longValue is polymorphic over x's value
+  @SuppressWarnings({"fallthrough","lowerbound:argument"// x fits in a long, then longValue is polymorphic over x's value
           // with respect to the lowerbound type system. 
   })
-  public static int log10(@Positive BigInteger x, RoundingMode mode) {
+  public static int log10(BigInteger x, RoundingMode mode) {
     checkPositive("x", x);
     if (fitsInLong(x)) {
-      return LongMath.log10(x.longValue(), mode);//(1)
+      return LongMath.log10(x.longValue(), mode); // (1)
     }
 
     int approxLog10 = (int) (log2(x, FLOOR) * LN_2 / LN_10);
@@ -393,7 +394,7 @@ public static BigInteger divide(BigInteger p, BigInteger q, RoundingMode mode) {
    *
    * @throws IllegalArgumentException if {@code n < 0}
    */
-  @SuppressWarnings("lowerbound:assignment.type.incompatible")/* (1): Since `n` is required to be non negative,
+  @SuppressWarnings("lowerbound:assignment")/* (1): Since `n` is required to be non negative,
   IntMath.divide() return a non negative value */
   public static BigInteger factorial(@NonNegative int n) {
     checkNonNegative("n", n);
@@ -450,7 +451,6 @@ public static BigInteger factorial(@NonNegative int n) {
     return listProduct(bignums).shiftLeft(shift);
   }
 
-  @SuppressWarnings("lowerbound:argument.type.incompatible")//List<BigInteger> is a mutable length data type.
   static BigInteger listProduct(List<BigInteger> nums) {
     return listProduct(nums, 0, nums.size());
   }
@@ -480,6 +480,7 @@ static BigInteger listProduct(List<BigInteger> nums, @NonNegative int start, @No
    *
    * @throws IllegalArgumentException if {@code n < 0}, {@code k < 0}, or {@code k > n}
    */
+  @SuppressWarnings("upperbound:argument")
   public static BigInteger binomial(@NonNegative @LTLengthOf("LongMath.factorials") int n, @NonNegative @LessThan("#1 + 1") int k) {
     checkNonNegative("n", n);
     checkNonNegative("k", k);
diff --git a/guava/src/com/google/common/math/DoubleMath.java b/guava/src/com/google/common/math/DoubleMath.java
index 1732198bfcd4..ef3f7cd0618a 100644
--- a/guava/src/com/google/common/math/DoubleMath.java
+++ b/guava/src/com/google/common/math/DoubleMath.java
@@ -48,6 +48,7 @@
  * @since 11.0
  */
 @GwtCompatible(emulated = true)
+@ElementTypesAreNonnullByDefault
 public final class DoubleMath {
   /*
    * This method returns a value y such that rounding y DOWN (towards zero) gives the same result as
@@ -435,7 +436,7 @@ public static double mean(double @MinLen(1)... values) {
   @Deprecated
   public static double mean(int... values) {
     checkArgument(values.length > 0, "Cannot take mean of 0 values");
-    // The upper bound on the the length of an array and the bounds on the int values mean that, in
+    // The upper bound on the length of an array and the bounds on the int values mean that, in
     // this case only, we can compute the sum as a long without risking overflow or loss of
     // precision. So we do that, as it's slightly quicker than the Knuth algorithm.
     long sum = 0;
diff --git a/guava/src/com/google/common/math/DoubleUtils.java b/guava/src/com/google/common/math/DoubleUtils.java
index 4183195fc714..d4a07e9dfcfe 100644
--- a/guava/src/com/google/common/math/DoubleUtils.java
+++ b/guava/src/com/google/common/math/DoubleUtils.java
@@ -33,6 +33,7 @@
  * @author Louis Wasserman
  */
 @GwtIncompatible
+@ElementTypesAreNonnullByDefault
 final class DoubleUtils {
   private DoubleUtils() {}
 
diff --git a/guava/src/com/google/common/math/ElementTypesAreNonnullByDefault.java b/guava/src/com/google/common/math/ElementTypesAreNonnullByDefault.java
new file mode 100644
index 000000000000..84999ea49499
--- /dev/null
+++ b/guava/src/com/google/common/math/ElementTypesAreNonnullByDefault.java
@@ -0,0 +1,41 @@
+/*
+ * Copyright (C) 2021 The Guava Authors
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package com.google.common.math;
+
+import static java.lang.annotation.ElementType.FIELD;
+import static java.lang.annotation.ElementType.METHOD;
+import static java.lang.annotation.ElementType.PARAMETER;
+import static java.lang.annotation.ElementType.TYPE;
+import static java.lang.annotation.RetentionPolicy.RUNTIME;
+
+import com.google.common.annotations.GwtCompatible;
+import java.lang.annotation.Retention;
+import java.lang.annotation.Target;
+import javax.annotation.Nonnull;
+import javax.annotation.meta.TypeQualifierDefault;
+
+/**
+ * Marks all "top-level" types as non-null in a way that is recognized by Kotlin. Note that this
+ * unfortunately includes type-variable usages, so we also provide {@link ParametricNullness} to
+ * "undo" it as best we can.
+ */
+@GwtCompatible
+@Retention(RUNTIME)
+@Target(TYPE)
+@TypeQualifierDefault({FIELD, METHOD, PARAMETER})
+@Nonnull
+@interface ElementTypesAreNonnullByDefault {}
diff --git a/guava/src/com/google/common/math/IntMath.java b/guava/src/com/google/common/math/IntMath.java
index 20d21e21bcbe..a90ef88ec705 100644
--- a/guava/src/com/google/common/math/IntMath.java
+++ b/guava/src/com/google/common/math/IntMath.java
@@ -54,6 +54,7 @@
  * @since 11.0
  */
 @GwtCompatible(emulated = true)
+@ElementTypesAreNonnullByDefault
 public final class IntMath {
   // NOTE: Whenever both tests are cheap and functional, it's faster to use &, | instead of &&, ||
 
@@ -105,7 +106,7 @@ public static boolean isPowerOfTwo(int x) {
    * a signed int. The implementation is branch-free, and benchmarks suggest it is measurably (if
    * narrowly) faster than the straightforward ternary expression.
    */
-  @SuppressWarnings("value:return.type.incompatible")/* An int has 32 bits, the lestmost bit is 0 for positive values, and is 1 for negative values.
+  @SuppressWarnings("value:return") /* An int has 32 bits, the leftmost bit is 0 for positive values, and is 1 for negative values.
   For shift right zero fill operator( >>> ), the left operands value is moved right by the number of bits specified by the right operand
   and shifted values are filled up with zeros. Therefore if x > y, (x - y) return a positive value, when being shifted 31 bits, it returns 0, otherwise return 1.
   */
@@ -190,7 +191,7 @@ public static int log10(@Positive int x, RoundingMode mode) {
     }
   }
 
-  @SuppressWarnings("lowerbound:return.type.incompatible")/*(1): `log10Floor()` returns a negative value if y is 0 and
+  @SuppressWarnings("lowerbound:return")/*(1): `log10Floor()` returns a negative value if y is 0 and
   `lessThanBranchFree(x, powersOf10[y])` returns 1( when x < powersOf10[y]). Since y = maxLog10ForLeadingZeros[Integer.numberOfLeadingZeros(x)],
   y is 0 when 0 < x < 8( the array `maxLog10ForLeadingZeros` has 0 values at indexes: 29, 30, 31, 32).
   Since when 0 < x < 8, y is 0 and powersOf10[0] is 1, x can't be < `powersOf10[y]`, therefore `log10Floor()` won't return
diff --git a/guava/src/com/google/common/math/LinearTransformation.java b/guava/src/com/google/common/math/LinearTransformation.java
index 485b04660902..4cc1eb87dbe9 100644
--- a/guava/src/com/google/common/math/LinearTransformation.java
+++ b/guava/src/com/google/common/math/LinearTransformation.java
@@ -21,6 +21,7 @@
 import com.google.common.annotations.Beta;
 import com.google.common.annotations.GwtIncompatible;
 import com.google.errorprone.annotations.concurrent.LazyInit;
+import javax.annotation.CheckForNull;
 
 /**
  * The representation of a linear transformation between real numbers {@code x} and {@code y}.
@@ -35,6 +36,7 @@
  */
 @Beta
 @GwtIncompatible
+@ElementTypesAreNonnullByDefault
 public abstract class LinearTransformation {
 
   /**
@@ -161,7 +163,7 @@ private static final class RegularLinearTransformation extends LinearTransformat
     final double slope;
     final double yIntercept;
 
-    @LazyInit LinearTransformation inverse;
+    @CheckForNull @LazyInit LinearTransformation inverse;
 
     RegularLinearTransformation(double slope, double yIntercept) {
       this.slope = slope;
@@ -219,7 +221,7 @@ private static final class VerticalLinearTransformation extends LinearTransforma
 
     final double x;
 
-    @LazyInit LinearTransformation inverse;
+    @CheckForNull @LazyInit LinearTransformation inverse;
 
     VerticalLinearTransformation(double x) {
       this.x = x;
diff --git a/guava/src/com/google/common/math/LongMath.java b/guava/src/com/google/common/math/LongMath.java
index 367d80f70111..55860e7bae86 100644
--- a/guava/src/com/google/common/math/LongMath.java
+++ b/guava/src/com/google/common/math/LongMath.java
@@ -57,6 +57,7 @@
  * @since 11.0
  */
 @GwtCompatible(emulated = true)
+@ElementTypesAreNonnullByDefault
 public final class LongMath {
   // NOTE: Whenever both tests are cheap and functional, it's faster to use &, | instead of &&, ||
 
@@ -111,7 +112,7 @@ public static boolean isPowerOfTwo(long x) {
    * signed long. The implementation is branch-free, and benchmarks suggest it is measurably faster
    * than the straightforward ternary expression.
    */
-  @SuppressWarnings("signedness:shift.unsigned")
+  @SuppressWarnings({"signedness:shift.unsigned", "value:return"})
   @VisibleForTesting
   static @IntRange(from = 0, to = 1) int lessThanBranchFree(long x, long y) {
     // Returns the sign bit of x - y.
@@ -434,7 +435,7 @@ public static long divide(long p, long q, RoundingMode mode) {
         // subtracting two nonnegative longs can't overflow
         // cmpRemToHalfDivisor has the same sign as compare(abs(rem), abs(q) / 2).
         if (cmpRemToHalfDivisor == 0) { // exactly on the half mark
-          increment = (mode == HALF_UP | (mode == HALF_EVEN & (div & 1) != 0));
+          increment = (mode == HALF_UP || (mode == HALF_EVEN && (div & 1) != 0));
         } else {
           increment = cmpRemToHalfDivisor > 0; // closer to the UP value
         }
@@ -1014,6 +1015,7 @@ public static long mean(long x, long y) {
    */
   @GwtIncompatible // TODO
   @Beta
+  @SuppressWarnings("signedness:comparison") // n is guaranteed to be positive
   public static boolean isPrime(long n) {
     if (n < 2) {
       checkNonNegative("n", n);
@@ -1054,7 +1056,6 @@ public static boolean isPrime(long n) {
       return true;
     }
 
-    //@SuppressWarnings("signedness:comparison") // n is guaranteed to be positive
     for (@Unsigned long[] baseSet : millerRabinBaseSets) {
       if (n <= baseSet[0]) {
         for (int i = 1; i < baseSet.length; i++) {
@@ -1075,6 +1076,7 @@ public static boolean isPrime(long n) {
    * NOTE: We could get slightly better bases that would be treated as unsigned, but benchmarks
    * showed negligible performance improvements.
    */
+  @SuppressWarnings("signedness:assignment") // all of the constants are positive
   private static final @Unsigned long[] @MinLen(1)[] millerRabinBaseSets = {
     {291830, 126401071349994536L},
     {885594168, 725270293939359937L, 3569819667048198375L},
@@ -1208,6 +1210,7 @@ static boolean test(@Unsigned long base, @Unsigned long n) {
     abstract @Unsigned long squareMod(@Unsigned long a, @Unsigned long m);
 
     /** Returns a^p mod m. */
+    @SuppressWarnings("signedness:compound.assignment.shift.signed")
     private @Unsigned long powMod(@Unsigned long a, @Unsigned long p, @Unsigned long m) {
       @Unsigned long res = 1;
       for (; p != 0; p >>= 1) {
@@ -1220,8 +1223,10 @@ static boolean test(@Unsigned long base, @Unsigned long n) {
     }
 
     /** Returns true if n is a strong probable prime relative to the specified base. */
+    @SuppressWarnings("signedness:compound.assignment.unsigned.variable")
     private boolean testWitness(@Unsigned long base, @Unsigned long n) {
       int r = Long.numberOfTrailingZeros(n - 1);
+      @SuppressWarnings("signedness:shift.signed")
       long d = (n - 1) >> r;
       base %= n;
       if (base == 0) {
diff --git a/guava/src/com/google/common/math/MathPreconditions.java b/guava/src/com/google/common/math/MathPreconditions.java
index ec860d0bf781..37d608a82329 100644
--- a/guava/src/com/google/common/math/MathPreconditions.java
+++ b/guava/src/com/google/common/math/MathPreconditions.java
@@ -18,7 +18,6 @@
 import com.google.errorprone.annotations.CanIgnoreReturnValue;
 import java.math.BigInteger;
 import java.math.RoundingMode;
-import org.checkerframework.checker.nullness.qual.Nullable;
 
 /**
  * A collection of preconditions for math functions.
@@ -27,50 +26,51 @@
  */
 @GwtCompatible
 @CanIgnoreReturnValue
+@ElementTypesAreNonnullByDefault
 final class MathPreconditions {
-  static int checkPositive(@Nullable String role, int x) {
+  static int checkPositive(String role, int x) {
     if (x <= 0) {
       throw new IllegalArgumentException(role + " (" + x + ") must be > 0");
     }
     return x;
   }
 
-  static long checkPositive(@Nullable String role, long x) {
+  static long checkPositive(String role, long x) {
     if (x <= 0) {
       throw new IllegalArgumentException(role + " (" + x + ") must be > 0");
     }
     return x;
   }
 
-  static BigInteger checkPositive(@Nullable String role, BigInteger x) {
+  static BigInteger checkPositive(String role, BigInteger x) {
     if (x.signum() <= 0) {
       throw new IllegalArgumentException(role + " (" + x + ") must be > 0");
     }
     return x;
   }
 
-  static int checkNonNegative(@Nullable String role, int x) {
+  static int checkNonNegative(String role, int x) {
     if (x < 0) {
       throw new IllegalArgumentException(role + " (" + x + ") must be >= 0");
     }
     return x;
   }
 
-  static long checkNonNegative(@Nullable String role, long x) {
+  static long checkNonNegative(String role, long x) {
     if (x < 0) {
       throw new IllegalArgumentException(role + " (" + x + ") must be >= 0");
     }
     return x;
   }
 
-  static BigInteger checkNonNegative(@Nullable String role, BigInteger x) {
+  static BigInteger checkNonNegative(String role, BigInteger x) {
     if (x.signum() < 0) {
       throw new IllegalArgumentException(role + " (" + x + ") must be >= 0");
     }
     return x;
   }
 
-  static double checkNonNegative(@Nullable String role, double x) {
+  static double checkNonNegative(String role, double x) {
     if (!(x >= 0)) { // not x < 0, to work with NaN.
       throw new IllegalArgumentException(role + " (" + x + ") must be >= 0");
     }
diff --git a/guava/src/com/google/common/math/PairedStats.java b/guava/src/com/google/common/math/PairedStats.java
index 6b9c778d1d62..31ab9b71966f 100644
--- a/guava/src/com/google/common/math/PairedStats.java
+++ b/guava/src/com/google/common/math/PairedStats.java
@@ -28,7 +28,7 @@
 import java.io.Serializable;
 import java.nio.ByteBuffer;
 import java.nio.ByteOrder;
-import org.checkerframework.checker.nullness.qual.Nullable;
+import javax.annotation.CheckForNull;
 
 /**
  * An immutable value object capturing some basic statistics about a collection of paired double
@@ -39,6 +39,7 @@
  */
 @Beta
 @GwtIncompatible
+@ElementTypesAreNonnullByDefault
 public final class PairedStats implements Serializable {
 
   private final Stats xStats;
@@ -213,7 +214,7 @@ public LinearTransformation leastSquaresFit() {
    * guarantees {@code strictfp}-like semantics.)
    */
   @Override
-  public boolean equals(@Nullable Object obj) {
+  public boolean equals(@CheckForNull Object obj) {
     if (obj == null) {
       return false;
     }
diff --git a/guava/src/com/google/common/math/PairedStatsAccumulator.java b/guava/src/com/google/common/math/PairedStatsAccumulator.java
index a9884959a04a..072ef13b3b17 100644
--- a/guava/src/com/google/common/math/PairedStatsAccumulator.java
+++ b/guava/src/com/google/common/math/PairedStatsAccumulator.java
@@ -32,6 +32,7 @@
  */
 @Beta
 @GwtIncompatible
+@ElementTypesAreNonnullByDefault
 public final class PairedStatsAccumulator {
 
   // These fields must satisfy the requirements of PairedStats' constructor as well as those of the
diff --git a/guava/src/com/google/common/math/ParametricNullness.java b/guava/src/com/google/common/math/ParametricNullness.java
new file mode 100644
index 000000000000..8e57826e4335
--- /dev/null
+++ b/guava/src/com/google/common/math/ParametricNullness.java
@@ -0,0 +1,52 @@
+/*
+ * Copyright (C) 2021 The Guava Authors
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package com.google.common.math;
+
+import static java.lang.annotation.ElementType.FIELD;
+import static java.lang.annotation.ElementType.METHOD;
+import static java.lang.annotation.ElementType.PARAMETER;
+import static java.lang.annotation.RetentionPolicy.RUNTIME;
+
+import com.google.common.annotations.GwtCompatible;
+import java.lang.annotation.Retention;
+import java.lang.annotation.Target;
+
+/**
+ * Marks a "top-level" type-variable usage as the closest we can get to "non-nullable when
+ * non-nullable; nullable when nullable" (like the Android <a
+ * href="https://android.googlesource.com/platform/libcore/+/master/luni/src/main/java/libcore/util/NullFromTypeParam.java">{@code
+ * NullFromTypeParam}</a>).
+ *
+ * <p>Consumers of this annotation include:
+ *
+ * <ul>
+ *   <li>Kotlin, for which it makes the type-variable usage (a) a Kotlin platform type when the type
+ *       argument is non-nullable and (b) nullable when the type argument is nullable. We use this
+ *       to "undo" {@link ElementTypesAreNonnullByDefault}.
+ *   <li><a href="https://developers.google.com/j2objc">J2ObjC</a>
+ *   <li>{@code NullPointerTester}, at least in the Android backport (where the type-use annotations
+ *       {@code NullPointerTester} would need are not available) and in case of <a
+ *       href="https://bugs.openjdk.java.net/browse/JDK-8202469">JDK-8202469</a>
+ * </ul>
+ *
+ */
+@GwtCompatible
+@Retention(RUNTIME)
+@Target({FIELD, METHOD, PARAMETER})
+@javax.annotation.meta.TypeQualifierNickname
+@javax.annotation.Nonnull(when = javax.annotation.meta.When.UNKNOWN)
+@interface ParametricNullness {}
diff --git a/guava/src/com/google/common/math/Quantiles.java b/guava/src/com/google/common/math/Quantiles.java
index cd8a424443b3..01bdcc71db90 100644
--- a/guava/src/com/google/common/math/Quantiles.java
+++ b/guava/src/com/google/common/math/Quantiles.java
@@ -134,6 +134,7 @@
  */
 @Beta
 @GwtIncompatible
+@ElementTypesAreNonnullByDefault
 public final class Quantiles {
 
   /** Specifies the computation of a median (i.e. the 1st 2-quantile). */
diff --git a/guava/src/com/google/common/math/Stats.java b/guava/src/com/google/common/math/Stats.java
index b59971c88c84..e7ecc97350ca 100644
--- a/guava/src/com/google/common/math/Stats.java
+++ b/guava/src/com/google/common/math/Stats.java
@@ -36,6 +36,7 @@
 import java.util.stream.DoubleStream;
 import java.util.stream.IntStream;
 import java.util.stream.LongStream;
+import javax.annotation.CheckForNull;
 import org.checkerframework.checker.nullness.qual.Nullable;
 import org.checkerframework.common.value.qual.MinLen;
 
@@ -65,6 +66,7 @@
  */
 @Beta
 @GwtIncompatible
+@ElementTypesAreNonnullByDefault
 public final class Stats implements Serializable {
 
   private final long count;
@@ -417,7 +419,7 @@ public double max() {
    * {@code strictfp}-like semantics.)
    */
   @Override
-  public boolean equals(@Nullable Object obj) {
+  public boolean equals(@CheckForNull Object obj) {
     if (obj == null) {
       return false;
     }
diff --git a/guava/src/com/google/common/math/StatsAccumulator.java b/guava/src/com/google/common/math/StatsAccumulator.java
index 0670cb1a85e2..b28229c9625e 100644
--- a/guava/src/com/google/common/math/StatsAccumulator.java
+++ b/guava/src/com/google/common/math/StatsAccumulator.java
@@ -37,6 +37,7 @@
  */
 @Beta
 @GwtIncompatible
+@ElementTypesAreNonnullByDefault
 public final class StatsAccumulator {
 
   // These fields must satisfy the requirements of Stats' constructor as well as those of the stat
diff --git a/guava/src/com/google/common/math/ToDoubleRounder.java b/guava/src/com/google/common/math/ToDoubleRounder.java
index 7525e3f990f1..2e7e7fae0944 100644
--- a/guava/src/com/google/common/math/ToDoubleRounder.java
+++ b/guava/src/com/google/common/math/ToDoubleRounder.java
@@ -25,6 +25,7 @@
  * a {@link RoundingMode}.
  */
 @GwtIncompatible
+@ElementTypesAreNonnullByDefault
 abstract class ToDoubleRounder<X extends Number & Comparable<X>> {
   /**
    * Returns x rounded to either the greatest double less than or equal to the precise value of x,
diff --git a/guava/src/com/google/common/net/ElementTypesAreNonnullByDefault.java b/guava/src/com/google/common/net/ElementTypesAreNonnullByDefault.java
new file mode 100644
index 000000000000..d8cfd7377d0e
--- /dev/null
+++ b/guava/src/com/google/common/net/ElementTypesAreNonnullByDefault.java
@@ -0,0 +1,41 @@
+/*
+ * Copyright (C) 2021 The Guava Authors
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package com.google.common.net;
+
+import static java.lang.annotation.ElementType.FIELD;
+import static java.lang.annotation.ElementType.METHOD;
+import static java.lang.annotation.ElementType.PARAMETER;
+import static java.lang.annotation.ElementType.TYPE;
+import static java.lang.annotation.RetentionPolicy.RUNTIME;
+
+import com.google.common.annotations.GwtCompatible;
+import java.lang.annotation.Retention;
+import java.lang.annotation.Target;
+import javax.annotation.Nonnull;
+import javax.annotation.meta.TypeQualifierDefault;
+
+/**
+ * Marks all "top-level" types as non-null in a way that is recognized by Kotlin. Note that this
+ * unfortunately includes type-variable usages, so we also provide {@link ParametricNullness} to
+ * "undo" it as best we can.
+ */
+@GwtCompatible
+@Retention(RUNTIME)
+@Target(TYPE)
+@TypeQualifierDefault({FIELD, METHOD, PARAMETER})
+@Nonnull
+@interface ElementTypesAreNonnullByDefault {}
diff --git a/guava/src/com/google/common/net/HostAndPort.java b/guava/src/com/google/common/net/HostAndPort.java
index c01b87a15cd5..a27eb65ff3ba 100644
--- a/guava/src/com/google/common/net/HostAndPort.java
+++ b/guava/src/com/google/common/net/HostAndPort.java
@@ -18,13 +18,14 @@
 import static com.google.common.base.Preconditions.checkNotNull;
 import static com.google.common.base.Preconditions.checkState;
 
-import com.google.common.annotations.Beta;
 import com.google.common.annotations.GwtCompatible;
+import com.google.common.base.CharMatcher;
 import com.google.common.base.Objects;
 import com.google.common.base.Strings;
+import com.google.errorprone.annotations.CanIgnoreReturnValue;
 import com.google.errorprone.annotations.Immutable;
 import java.io.Serializable;
-import org.checkerframework.checker.nullness.qual.Nullable;
+import javax.annotation.CheckForNull;
 
 /**
  * An immutable representation of a host and port.
@@ -59,9 +60,9 @@
  * @author Paul Marks
  * @since 10.0
  */
-@Beta
 @Immutable
 @GwtCompatible
+@ElementTypesAreNonnullByDefault
 public final class HostAndPort implements Serializable {
   /** Magic value indicating the absence of a port number. */
   private static final int NO_PORT = -1;
@@ -162,6 +163,7 @@ public static HostAndPort fromHost(String host) {
    * @return if parsing was successful, a populated HostAndPort object.
    * @throws IllegalArgumentException if nothing meaningful could be parsed.
    */
+  @CanIgnoreReturnValue // TODO(b/219820829): consider removing
   public static HostAndPort fromString(String hostPortString) {
     checkNotNull(hostPortString);
     String host;
@@ -189,7 +191,10 @@ public static HostAndPort fromString(String hostPortString) {
     if (!Strings.isNullOrEmpty(portString)) {
       // Try to parse the whole port string as a number.
       // JDK7 accepts leading plus signs. We don't want to.
-      checkArgument(!portString.startsWith("+"), "Unparseable port number: %s", hostPortString);
+      checkArgument(
+          !portString.startsWith("+") && CharMatcher.ascii().matchesAllOf(portString),
+          "Unparseable port number: %s",
+          hostPortString);
       try {
         port = Integer.parseInt(portString);
       } catch (NumberFormatException e) {
@@ -209,14 +214,12 @@ public static HostAndPort fromString(String hostPortString) {
    * @throws IllegalArgumentException if parsing the bracketed host-port string fails.
    */
   private static String[] getHostAndPortFromBracketedHost(String hostPortString) {
-    int colonIndex = 0;
-    int closeBracketIndex = 0;
     checkArgument(
         hostPortString.charAt(0) == '[',
         "Bracketed host-port string must start with a bracket: %s",
         hostPortString);
-    colonIndex = hostPortString.indexOf(':');
-    closeBracketIndex = hostPortString.lastIndexOf(']');
+    int colonIndex = hostPortString.indexOf(':');
+    int closeBracketIndex = hostPortString.lastIndexOf(']');
     checkArgument(
         colonIndex > -1 && closeBracketIndex > colonIndex,
         "Invalid bracketed host/port: %s",
@@ -271,13 +274,14 @@ public HostAndPort withDefaultPort(int defaultPort) {
    * @return {@code this}, to enable chaining of calls.
    * @throws IllegalArgumentException if bracketless IPv6 is detected.
    */
+  @CanIgnoreReturnValue
   public HostAndPort requireBracketsForIPv6() {
     checkArgument(!hasBracketlessColons, "Possible bracketless IPv6 literal: %s", host);
     return this;
   }
 
   @Override
-  public boolean equals(@Nullable Object other) {
+  public boolean equals(@CheckForNull Object other) {
     if (this == other) {
       return true;
     }
diff --git a/guava/src/com/google/common/net/HostSpecifier.java b/guava/src/com/google/common/net/HostSpecifier.java
index bb523a0ce517..c57f3d97593c 100644
--- a/guava/src/com/google/common/net/HostSpecifier.java
+++ b/guava/src/com/google/common/net/HostSpecifier.java
@@ -14,12 +14,12 @@
 
 package com.google.common.net;
 
-import com.google.common.annotations.Beta;
 import com.google.common.annotations.GwtIncompatible;
 import com.google.common.base.Preconditions;
+import com.google.errorprone.annotations.CanIgnoreReturnValue;
 import java.net.InetAddress;
 import java.text.ParseException;
-import org.checkerframework.checker.nullness.qual.Nullable;
+import javax.annotation.CheckForNull;
 
 /**
  * A syntactically valid host specifier, suitable for use in a URI. This may be either a numeric IP
@@ -41,8 +41,8 @@
  * @author Craig Berry
  * @since 5.0
  */
-@Beta
 @GwtIncompatible
+@ElementTypesAreNonnullByDefault
 public final class HostSpecifier {
 
   private final String canonicalForm;
@@ -70,9 +70,9 @@ private HostSpecifier(String canonicalForm) {
   public static HostSpecifier fromValid(String specifier) {
     // Verify that no port was specified, and strip optional brackets from
     // IPv6 literals.
-    final HostAndPort parsedHost = HostAndPort.fromString(specifier);
+    HostAndPort parsedHost = HostAndPort.fromString(specifier);
     Preconditions.checkArgument(!parsedHost.hasPort());
-    final String host = parsedHost.getHost();
+    String host = parsedHost.getHost();
 
     // Try to interpret the specifier as an IP address. Note we build
     // the address rather than using the .is* methods because we want to
@@ -92,7 +92,7 @@ public static HostSpecifier fromValid(String specifier) {
     // It is not any kind of IP address; must be a domain name or invalid.
 
     // TODO(user): different versions of this for different factories?
-    final InternetDomainName domain = InternetDomainName.from(host);
+    InternetDomainName domain = InternetDomainName.from(host);
 
     if (domain.hasPublicSuffix()) {
       return new HostSpecifier(domain.toString());
@@ -109,6 +109,7 @@ public static HostSpecifier fromValid(String specifier) {
    *
    * @throws ParseException if the specifier is not valid.
    */
+  @CanIgnoreReturnValue // TODO(b/219820829): consider removing
   public static HostSpecifier from(String specifier) throws ParseException {
     try {
       return fromValid(specifier);
@@ -129,7 +130,7 @@ public static HostSpecifier from(String specifier) throws ParseException {
    */
   public static boolean isValid(String specifier) {
     try {
-      fromValid(specifier);
+      HostSpecifier unused = fromValid(specifier);
       return true;
     } catch (IllegalArgumentException e) {
       return false;
@@ -137,13 +138,13 @@ public static boolean isValid(String specifier) {
   }
 
   @Override
-  public boolean equals(@Nullable Object other) {
+  public boolean equals(@CheckForNull Object other) {
     if (this == other) {
       return true;
     }
 
     if (other instanceof HostSpecifier) {
-      final HostSpecifier that = (HostSpecifier) other;
+      HostSpecifier that = (HostSpecifier) other;
       return this.canonicalForm.equals(that.canonicalForm);
     }
 
diff --git a/guava/src/com/google/common/net/HttpHeaders.java b/guava/src/com/google/common/net/HttpHeaders.java
index 2755a8fc9d2c..2ecbfaa8cb48 100644
--- a/guava/src/com/google/common/net/HttpHeaders.java
+++ b/guava/src/com/google/common/net/HttpHeaders.java
@@ -14,7 +14,6 @@
 
 package com.google.common.net;
 
-import com.google.common.annotations.Beta;
 import com.google.common.annotations.GwtCompatible;
 
 /**
@@ -32,6 +31,7 @@
  * @since 11.0
  */
 @GwtCompatible
+@ElementTypesAreNonnullByDefault
 public final class HttpHeaders {
   private HttpHeaders() {}
 
@@ -101,7 +101,6 @@ private HttpHeaders() {}
    *
    * @since 17.0
    */
-  @Beta
   public static final String FOLLOW_ONLY_WHEN_PRERENDER_SHOWN = "Follow-Only-When-Prerender-Shown";
   /** The HTTP {@code Host} header field name. */
   public static final String HOST = "Host";
@@ -200,6 +199,14 @@ private ReferrerPolicyValues() {}
   public static final String ACCESS_CONTROL_ALLOW_METHODS = "Access-Control-Allow-Methods";
   /** The HTTP {@code Access-Control-Allow-Origin} header field name. */
   public static final String ACCESS_CONTROL_ALLOW_ORIGIN = "Access-Control-Allow-Origin";
+  /**
+   * The HTTP <a href="https://wicg.github.io/private-network-access/#headers">{@code
+   * Access-Control-Allow-Private-Network}</a> header field name.
+   *
+   * @since 31.1
+   */
+  public static final String ACCESS_CONTROL_ALLOW_PRIVATE_NETWORK =
+      "Access-Control-Allow-Private-Network";
   /** The HTTP {@code Access-Control-Allow-Credentials} header field name. */
   public static final String ACCESS_CONTROL_ALLOW_CREDENTIALS = "Access-Control-Allow-Credentials";
   /** The HTTP {@code Access-Control-Expose-Headers} header field name. */
@@ -303,6 +310,12 @@ private ReferrerPolicyValues() {}
   public static final String LINK = "Link";
   /** The HTTP {@code Location} header field name. */
   public static final String LOCATION = "Location";
+  /**
+   * The HTTP {@code Keep-Alive} header field name.
+   *
+   * @since 31.0
+   */
+  public static final String KEEP_ALIVE = "Keep-Alive";
   /**
    * The HTTP <a href="https://googlechrome.github.io/OriginTrials/#header">{@code Origin-Trial}</a>
    * header field name.
@@ -350,7 +363,7 @@ private ReferrerPolicyValues() {}
    *
    * @since 27.1
    */
-  @Beta public static final String SOURCE_MAP = "SourceMap";
+  public static final String SOURCE_MAP = "SourceMap";
 
   /**
    * The HTTP <a href="http://tools.ietf.org/html/rfc6797#section-6.1">{@code
@@ -381,6 +394,45 @@ private ReferrerPolicyValues() {}
   public static final String DNT = "DNT";
   /** The HTTP {@code X-Content-Type-Options} header field name. */
   public static final String X_CONTENT_TYPE_OPTIONS = "X-Content-Type-Options";
+  /**
+   * The HTTP <a
+   * href="https://iabtechlab.com/wp-content/uploads/2019/06/VAST_4.2_final_june26.pdf">{@code
+   * X-Device-IP}</a> header field name. Header used for VAST requests to provide the IP address of
+   * the device on whose behalf the request is being made.
+   *
+   * @since 31.0
+   */
+  public static final String X_DEVICE_IP = "X-Device-IP";
+  /**
+   * The HTTP <a
+   * href="https://iabtechlab.com/wp-content/uploads/2019/06/VAST_4.2_final_june26.pdf">{@code
+   * X-Device-Referer}</a> header field name. Header used for VAST requests to provide the {@link
+   * #REFERER} header value that the on-behalf-of client would have used when making a request
+   * itself.
+   *
+   * @since 31.0
+   */
+  public static final String X_DEVICE_REFERER = "X-Device-Referer";
+  /**
+   * The HTTP <a
+   * href="https://iabtechlab.com/wp-content/uploads/2019/06/VAST_4.2_final_june26.pdf">{@code
+   * X-Device-Accept-Language}</a> header field name. Header used for VAST requests to provide the
+   * {@link #ACCEPT_LANGUAGE} header value that the on-behalf-of client would have used when making
+   * a request itself.
+   *
+   * @since 31.0
+   */
+  public static final String X_DEVICE_ACCEPT_LANGUAGE = "X-Device-Accept-Language";
+  /**
+   * The HTTP <a
+   * href="https://iabtechlab.com/wp-content/uploads/2019/06/VAST_4.2_final_june26.pdf">{@code
+   * X-Device-Requested-With}</a> header field name. Header used for VAST requests to provide the
+   * {@link #X_REQUESTED_WITH} header value that the on-behalf-of client would have used when making
+   * a request itself.
+   *
+   * @since 31.0
+   */
+  public static final String X_DEVICE_REQUESTED_WITH = "X-Device-Requested-With";
   /** The HTTP {@code X-Do-Not-Track} header field name. */
   public static final String X_DO_NOT_TRACK = "X-Do-Not-Track";
   /** The HTTP {@code X-Forwarded-For} header field name (superseded by {@code Forwarded}). */
@@ -409,14 +461,14 @@ private ReferrerPolicyValues() {}
    *
    * @since 15.0
    */
-  @Beta public static final String PUBLIC_KEY_PINS = "Public-Key-Pins";
+  public static final String PUBLIC_KEY_PINS = "Public-Key-Pins";
   /**
    * The HTTP <a href="http://tools.ietf.org/html/draft-evans-palmer-key-pinning">{@code
    * Public-Key-Pins-Report-Only}</a> header field name.
    *
    * @since 15.0
    */
-  @Beta public static final String PUBLIC_KEY_PINS_REPORT_ONLY = "Public-Key-Pins-Report-Only";
+  public static final String PUBLIC_KEY_PINS_REPORT_ONLY = "Public-Key-Pins-Report-Only";
   /**
    * The HTTP {@code X-Request-ID} header field name.
    *
@@ -436,7 +488,7 @@ private ReferrerPolicyValues() {}
    *
    * @since 24.1
    */
-  @Beta public static final String X_DOWNLOAD_OPTIONS = "X-Download-Options";
+  public static final String X_DOWNLOAD_OPTIONS = "X-Download-Options";
   /** The HTTP {@code X-XSS-Protection} header field name. */
   public static final String X_XSS_PROTECTION = "X-XSS-Protection";
   /**
@@ -486,6 +538,100 @@ private ReferrerPolicyValues() {}
    */
   public static final String X_MOZ = "X-Moz";
 
+  /**
+   * The HTTP <a
+   * href="https://developer.mozilla.org/en-US/docs/Web/HTTP/Headers/Device-Memory">{@code
+   * Device-Memory}</a> header field name.
+   *
+   * @since 31.0
+   */
+  public static final String DEVICE_MEMORY = "Device-Memory";
+
+  /**
+   * The HTTP <a href="https://developer.mozilla.org/en-US/docs/Web/HTTP/Headers/Downlink">{@code
+   * Downlink}</a> header field name.
+   *
+   * @since 31.0
+   */
+  public static final String DOWNLINK = "Downlink";
+
+  /**
+   * The HTTP <a href="https://developer.mozilla.org/en-US/docs/Web/HTTP/Headers/ECT">{@code
+   * ECT}</a> header field name.
+   *
+   * @since 31.0
+   */
+  public static final String ECT = "ECT";
+
+  /**
+   * The HTTP <a href="https://developer.mozilla.org/en-US/docs/Web/HTTP/Headers/RTT">{@code
+   * RTT}</a> header field name.
+   *
+   * @since 31.0
+   */
+  public static final String RTT = "RTT";
+
+  /**
+   * The HTTP <a href="https://developer.mozilla.org/en-US/docs/Web/HTTP/Headers/Save-Data">{@code
+   * Save-Data}</a> header field name.
+   *
+   * @since 31.0
+   */
+  public static final String SAVE_DATA = "Save-Data";
+
+  /**
+   * The HTTP <a
+   * href="https://developer.mozilla.org/en-US/docs/Web/HTTP/Headers/Viewport-Width">{@code
+   * Viewport-Width}</a> header field name.
+   *
+   * @since 31.0
+   */
+  public static final String VIEWPORT_WIDTH = "Viewport-Width";
+
+  /**
+   * The HTTP <a href="https://developer.mozilla.org/en-US/docs/Web/HTTP/Headers/Width">{@code
+   * Width}</a> header field name.
+   *
+   * @since 31.0
+   */
+  public static final String WIDTH = "Width";
+
+  /**
+   * The HTTP <a href="https://www.w3.org/TR/permissions-policy-1/">{@code Permissions-Policy}</a>
+   * header field name.
+   *
+   * @since 31.0
+   */
+  public static final String PERMISSIONS_POLICY = "Permissions-Policy";
+
+  /**
+   * The HTTP <a
+   * href="https://wicg.github.io/user-preference-media-features-headers/#sec-ch-prefers-color-scheme">{@code
+   * Sec-CH-Prefers-Color-Scheme}</a> header field name.
+   *
+   * <p>This header is experimental.
+   *
+   * @since 31.0
+   */
+  public static final String SEC_CH_PREFERS_COLOR_SCHEME = "Sec-CH-Prefers-Color-Scheme";
+
+  /**
+   * The HTTP <a
+   * href="https://www.rfc-editor.org/rfc/rfc8942#name-the-accept-ch-response-head">{@code
+   * Accept-CH}</a> header field name.
+   *
+   * @since 31.0
+   */
+  public static final String ACCEPT_CH = "Accept-CH";
+  /**
+   * The HTTP <a
+   * href="https://datatracker.ietf.org/doc/html/draft-davidben-http-client-hint-reliability-03.txt#section-3">{@code
+   * Critical-CH}</a> header field name.
+   *
+   * @since 31.0
+   */
+  public static final String CRITICAL_CH = "Critical-CH";
+
   /**
    * The HTTP <a href="https://wicg.github.io/ua-client-hints/#sec-ch-ua">{@code Sec-CH-UA}</a>
    * header field name.
@@ -494,47 +640,62 @@ private ReferrerPolicyValues() {}
    */
   public static final String SEC_CH_UA = "Sec-CH-UA";
   /**
-   * The HTTP <a href="https://wicg.github.io/ua-client-hints/#sec-ch-arch">{@code
+   * The HTTP <a href="https://wicg.github.io/ua-client-hints/#sec-ch-ua-arch">{@code
    * Sec-CH-UA-Arch}</a> header field name.
    *
    * @since 30.0
    */
   public static final String SEC_CH_UA_ARCH = "Sec-CH-UA-Arch";
   /**
-   * The HTTP <a href="https://wicg.github.io/ua-client-hints/#sec-ch-model">{@code
+   * The HTTP <a href="https://wicg.github.io/ua-client-hints/#sec-ch-ua-model">{@code
    * Sec-CH-UA-Model}</a> header field name.
    *
    * @since 30.0
    */
   public static final String SEC_CH_UA_MODEL = "Sec-CH-UA-Model";
   /**
-   * The HTTP <a href="https://wicg.github.io/ua-client-hints/#sec-ch-platform">{@code
+   * The HTTP <a href="https://wicg.github.io/ua-client-hints/#sec-ch-ua-platform">{@code
    * Sec-CH-UA-Platform}</a> header field name.
    *
    * @since 30.0
    */
   public static final String SEC_CH_UA_PLATFORM = "Sec-CH-UA-Platform";
   /**
-   * The HTTP <a href="https://wicg.github.io/ua-client-hints/#sec-ch-platform-version">{@code
+   * The HTTP <a href="https://wicg.github.io/ua-client-hints/#sec-ch-ua-platform-version">{@code
    * Sec-CH-UA-Platform-Version}</a> header field name.
    *
    * @since 30.0
    */
   public static final String SEC_CH_UA_PLATFORM_VERSION = "Sec-CH-UA-Platform-Version";
   /**
-   * The HTTP <a href="https://wicg.github.io/ua-client-hints/#sec-ch-full-version">{@code
+   * The HTTP <a href="https://wicg.github.io/ua-client-hints/#sec-ch-ua-full-version">{@code
    * Sec-CH-UA-Full-Version}</a> header field name.
    *
+   * @deprecated Prefer {@link SEC_CH_UA_FULL_VERSION_LIST}.
    * @since 30.0
    */
-  public static final String SEC_CH_UA_FULL_VERSION = "Sec-CH-UA-Full-Version";
+  @Deprecated public static final String SEC_CH_UA_FULL_VERSION = "Sec-CH-UA-Full-Version";
   /**
-   * The HTTP <a href="https://wicg.github.io/ua-client-hints/#sec-ch-mobile">{@code
+   * The HTTP <a href="https://wicg.github.io/ua-client-hints/#sec-ch-ua-full-version-list">{@code
+   * Sec-CH-UA-Full-Version}</a> header field name.
+   *
+   * @since 31.1
+   */
+  public static final String SEC_CH_UA_FULL_VERSION_LIST = "Sec-CH-UA-Full-Version-List";
+  /**
+   * The HTTP <a href="https://wicg.github.io/ua-client-hints/#sec-ch-ua-mobile">{@code
    * Sec-CH-UA-Mobile}</a> header field name.
    *
    * @since 30.0
    */
   public static final String SEC_CH_UA_MOBILE = "Sec-CH-UA-Mobile";
+  /**
+   * The HTTP <a href="https://wicg.github.io/ua-client-hints/#sec-ch-ua-bitness">{@code
+   * Sec-CH-UA-Bitness}</a> header field name.
+   *
+   * @since 31.0
+   */
+  public static final String SEC_CH_UA_BITNESS = "Sec-CH-UA-Bitness";
 
   /**
    * The HTTP <a href="https://w3c.github.io/webappsec-fetch-metadata/">{@code Sec-Fetch-Dest}</a>
diff --git a/guava/src/com/google/common/net/InetAddresses.java b/guava/src/com/google/common/net/InetAddresses.java
index d0881e8d1732..9881c803e1f3 100644
--- a/guava/src/com/google/common/net/InetAddresses.java
+++ b/guava/src/com/google/common/net/InetAddresses.java
@@ -17,13 +17,13 @@
 import static com.google.common.base.Preconditions.checkArgument;
 import static com.google.common.base.Preconditions.checkNotNull;
 
-import com.google.common.annotations.Beta;
 import com.google.common.annotations.GwtIncompatible;
 import com.google.common.base.CharMatcher;
 import com.google.common.base.MoreObjects;
 import com.google.common.hash.Hashing;
 import com.google.common.io.ByteStreams;
 import com.google.common.primitives.Ints;
+import com.google.errorprone.annotations.CanIgnoreReturnValue;
 import java.math.BigInteger;
 import java.net.Inet4Address;
 import java.net.Inet6Address;
@@ -32,7 +32,8 @@
 import java.nio.ByteBuffer;
 import java.util.Arrays;
 import java.util.Locale;
-import org.checkerframework.checker.nullness.qual.Nullable;
+import javax.annotation.CheckForNull;
+import org.checkerframework.checker.formatter.qual.FormatMethod;
 
 /**
  * Static utility methods pertaining to {@link InetAddress} instances.
@@ -95,8 +96,8 @@
  * @author Erik Kline
  * @since 5.0
  */
-@Beta
 @GwtIncompatible
+@ElementTypesAreNonnullByDefault
 public final class InetAddresses {
   private static final int IPV4_PART_COUNT = 4;
   private static final int IPV6_PART_COUNT = 8;
@@ -133,11 +134,17 @@ private static Inet4Address getInet4Address(byte[] bytes) {
    *
    * <p>Anything after a {@code %} in an IPv6 address is ignored (assumed to be a Scope ID).
    *
+   * <p>This method accepts non-ASCII digits, for example {@code "１９２.１６８.０.１"} (those are fullwidth
+   * characters). That is consistent with {@link InetAddress}, but not with various RFCs. If you
+   * want to accept ASCII digits only, you can use something like {@code
+   * CharMatcher.ascii().matchesAllOf(ipString)}.
+   *
    * @param ipString {@code String} containing an IPv4 or IPv6 string literal, e.g. {@code
    *     "192.168.0.1"} or {@code "2001:db8::1"}
    * @return {@link InetAddress} representing the argument
    * @throws IllegalArgumentException if the argument is not a valid IP string literal
    */
+  @CanIgnoreReturnValue // TODO(b/219820829): consider removing
   public static InetAddress forString(String ipString) {
     byte[] addr = ipStringToBytes(ipString);
 
@@ -153,6 +160,11 @@ public static InetAddress forString(String ipString) {
    * Returns {@code true} if the supplied string is a valid IP string literal, {@code false}
    * otherwise.
    *
+   * <p>This method accepts non-ASCII digits, for example {@code "１９２.１６８.０.１"} (those are fullwidth
+   * characters). That is consistent with {@link InetAddress}, but not with various RFCs. If you
+   * want to accept ASCII digits only, you can use something like {@code
+   * CharMatcher.ascii().matchesAllOf(ipString)}.
+   *
    * @param ipString {@code String} to evaluated as an IP string literal
    * @return {@code true} if the argument is a valid IP string literal
    */
@@ -161,7 +173,9 @@ public static boolean isInetAddress(String ipString) {
   }
 
   /** Returns {@code null} if unable to parse into a {@code byte[]}. */
-  private static byte @Nullable [] ipStringToBytes(String ipString) {
+  @CheckForNull
+  private static byte[] ipStringToBytes(String ipStringParam) {
+    String ipString = ipStringParam;
     // Make a first pass to categorize the characters in this string.
     boolean hasColon = false;
     boolean hasDot = false;
@@ -204,7 +218,8 @@ public static boolean isInetAddress(String ipString) {
     return null;
   }
 
-  private static byte @Nullable [] textToNumericFormatV4(String ipString) {
+  @CheckForNull
+  private static byte[] textToNumericFormatV4(String ipString) {
     if (IPV4_DELIMITER_MATCHER.countIn(ipString) + 1 != IPV4_PART_COUNT) {
       return null; // Wrong number of parts
     }
@@ -229,7 +244,8 @@ public static boolean isInetAddress(String ipString) {
     return bytes;
   }
 
-  private static byte @Nullable [] textToNumericFormatV6(String ipString) {
+  @CheckForNull
+  private static byte[] textToNumericFormatV6(String ipString) {
     // An address can have [2..8] colons.
     int delimiterCount = IPV6_DELIMITER_MATCHER.countIn(ipString);
     if (delimiterCount < 2 || delimiterCount > IPV6_PART_COUNT) {
@@ -299,7 +315,8 @@ public static boolean isInetAddress(String ipString) {
     return rawBytes.array();
   }
 
-  private static @Nullable String convertDottedQuadToHex(String ipString) {
+  @CheckForNull
+  private static String convertDottedQuadToHex(String ipString) {
     int lastColon = ipString.lastIndexOf(':');
     String initialPart = ipString.substring(0, lastColon + 1);
     String dottedQuad = ipString.substring(lastColon + 1);
@@ -496,10 +513,15 @@ public static String toUriString(InetAddress ip) {
    * Returns an InetAddress representing the literal IPv4 or IPv6 host portion of a URL, encoded in
    * the format specified by RFC 3986 section 3.2.2.
    *
-   * <p>This function is similar to {@link InetAddresses#forString(String)}, however, it requires
-   * that IPv6 addresses are surrounded by square brackets.
+   * <p>This method is similar to {@link InetAddresses#forString(String)}, however, it requires that
+   * IPv6 addresses are surrounded by square brackets.
+   *
+   * <p>This method is the inverse of {@link InetAddresses#toUriString(java.net.InetAddress)}.
    *
-   * <p>This function is the inverse of {@link InetAddresses#toUriString(java.net.InetAddress)}.
+   * <p>This method accepts non-ASCII digits, for example {@code "１９２.１６８.０.１"} (those are fullwidth
+   * characters). That is consistent with {@link InetAddress}, but not with various RFCs. If you
+   * want to accept ASCII digits only, you can use something like {@code
+   * CharMatcher.ascii().matchesAllOf(ipString)}.
    *
    * @param hostAddr A RFC 3986 section 3.2.2 encoded IPv4 or IPv6 address
    * @return an InetAddress representing the address in {@code hostAddr}
@@ -515,7 +537,8 @@ public static InetAddress forUriString(String hostAddr) {
     return addr;
   }
 
-  private static @Nullable InetAddress forUriStringNoThrow(String hostAddr) {
+  @CheckForNull
+  private static InetAddress forUriStringNoThrow(String hostAddr) {
     checkNotNull(hostAddr);
 
     // Decide if this should be an IPv6 or IPv4 address.
@@ -542,6 +565,11 @@ public static InetAddress forUriString(String hostAddr) {
    * Returns {@code true} if the supplied string is a valid URI IP string literal, {@code false}
    * otherwise.
    *
+   * <p>This method accepts non-ASCII digits, for example {@code "１９２.１６８.０.１"} (those are fullwidth
+   * characters). That is consistent with {@link InetAddress}, but not with various RFCs. If you
+   * want to accept ASCII digits only, you can use something like {@code
+   * CharMatcher.ascii().matchesAllOf(ipString)}.
+   *
    * @param ipString {@code String} to evaluated as an IP URI host string literal
    * @return {@code true} if the argument is a valid IP URI host
    */
@@ -640,7 +668,6 @@ public static Inet4Address get6to4IPv4Address(Inet6Address ip) {
    *
    * @since 5.0
    */
-  @Beta
   public static final class TeredoInfo {
     private final Inet4Address server;
     private final Inet4Address client;
@@ -658,7 +685,7 @@ public static final class TeredoInfo {
      */
     // TODO: why is this public?
     public TeredoInfo(
-        @Nullable Inet4Address server, @Nullable Inet4Address client, int port, int flags) {
+        @CheckForNull Inet4Address server, @CheckForNull Inet4Address client, int port, int flags) {
       checkArgument(
           (port >= 0) && (port <= 0xffff), "port '%s' is out of range (0 <= port <= 0xffff)", port);
       checkArgument(
@@ -746,6 +773,7 @@ public static TeredoInfo getTeredoInfo(Inet6Address ip) {
    * @param ip {@link Inet6Address} to be examined for ISATAP address format
    * @return {@code true} if the argument is an ISATAP address
    */
+  @SuppressWarnings("value:cast.unsafe") // ip address should probably be unsigned bytes
   public static boolean isIsatapAddress(Inet6Address ip) {
 
     // If it's a Teredo address with the right port (41217, or 0xa101)
@@ -837,10 +865,15 @@ public static Inet4Address getEmbeddedIPv4ClientAddress(Inet6Address ip) {
    * obscure {@link Inet6Address} methods, but it would be unwise to depend on such a
    * poorly-documented feature.)
    *
+   * <p>This method accepts non-ASCII digits. That is consistent with {@link InetAddress}, but not
+   * with various RFCs. If you want to accept ASCII digits only, you can use something like {@code
+   * CharMatcher.ascii().matchesAllOf(ipString)}.
+   *
    * @param ipString {@code String} to be examined for embedded IPv4-mapped IPv6 address format
    * @return {@code true} if the argument is a valid "mapped" address
    * @since 10.0
    */
+  @SuppressWarnings("value:cast.unsafe") // ip address should probably be unsigned bytes
   public static boolean isMappedIPv4Address(String ipString) {
     byte[] bytes = ipStringToBytes(ipString);
     if (bytes != null && bytes.length == 16) {
@@ -864,7 +897,7 @@ public static boolean isMappedIPv4Address(String ipString) {
    *
    * <p>HACK: As long as applications continue to use IPv4 addresses for indexing into tables,
    * accounting, et cetera, it may be necessary to <b>coerce</b> IPv6 addresses into IPv4 addresses.
-   * This function does so by hashing 64 bits of the IPv6 address into {@code 224.0.0.0/3} (64 bits
+   * This method does so by hashing 64 bits of the IPv6 address into {@code 224.0.0.0/3} (64 bits
    * into 29 bits):
    *
    * <ul>
@@ -874,7 +907,7 @@ public static boolean isMappedIPv4Address(String ipString) {
    *
    * <p>A "coerced" IPv4 address is equivalent to itself.
    *
-   * <p>NOTE: This function is failsafe for security purposes: ALL IPv6 addresses (except localhost
+   * <p>NOTE: This method is failsafe for security purposes: ALL IPv6 addresses (except localhost
    * (::1)) are hashed to avoid the security risk associated with extracting an embedded IPv4
    * address that might permit elevated privileges.
    *
@@ -912,7 +945,7 @@ public static Inet4Address getCoercedIPv4Address(InetAddress ip) {
     }
 
     // Many strategies for hashing are possible. This might suffice for now.
-    int coercedHash = Hashing.murmur3_32().hashLong(addressAsLong).asInt();
+    int coercedHash = Hashing.murmur3_32_fixed().hashLong(addressAsLong).asInt();
 
     // Squash into 224/4 Multicast and 240/4 Reserved space (i.e. 224/3).
     coercedHash |= 0xe0000000;
@@ -1063,6 +1096,7 @@ public static InetAddress fromLittleEndianByteArray(byte[] addr) throws UnknownH
    * @throws IllegalArgumentException if InetAddress is at the beginning of its range
    * @since 18.0
    */
+  @SuppressWarnings("value:cast.unsafe") // ip address should probably be unsigned bytes
   public static InetAddress decrement(InetAddress address) {
     byte[] addr = address.getAddress();
     int i = addr.length - 1;
@@ -1086,6 +1120,7 @@ public static InetAddress decrement(InetAddress address) {
    * @throws IllegalArgumentException if InetAddress is at the end of its range
    * @since 10.0
    */
+  @SuppressWarnings("value:cast.unsafe") // ip address should probably be unsigned bytes
   public static InetAddress increment(InetAddress address) {
     byte[] addr = address.getAddress();
     int i = addr.length - 1;
@@ -1108,16 +1143,18 @@ public static InetAddress increment(InetAddress address) {
    *     ffff:ffff:ffff:ffff:ffff:ffff:ffff:ffff for IPv6
    * @since 10.0
    */
+  @SuppressWarnings("value:cast.unsafe") // ip address should probably be unsigned bytes
   public static boolean isMaximum(InetAddress address) {
     byte[] addr = address.getAddress();
-    for (int i = 0; i < addr.length; i++) {
-      if (addr[i] != (byte) 0xff) {
+    for (byte b : addr) {
+      if (b != (byte) 0xff) {
         return false;
       }
     }
     return true;
   }
 
+  @FormatMethod
   private static IllegalArgumentException formatIllegalArgumentException(
       String format, Object... args) {
     return new IllegalArgumentException(String.format(Locale.ROOT, format, args));
diff --git a/guava/src/com/google/common/net/InternetDomainName.java b/guava/src/com/google/common/net/InternetDomainName.java
index 9b9be8177b53..d71a9d5c3c6c 100644
--- a/guava/src/com/google/common/net/InternetDomainName.java
+++ b/guava/src/com/google/common/net/InternetDomainName.java
@@ -18,7 +18,6 @@
 import static com.google.common.base.Preconditions.checkNotNull;
 import static com.google.common.base.Preconditions.checkState;
 
-import com.google.common.annotations.Beta;
 import com.google.common.annotations.GwtCompatible;
 import com.google.common.base.Ascii;
 import com.google.common.base.CharMatcher;
@@ -26,11 +25,12 @@
 import com.google.common.base.Optional;
 import com.google.common.base.Splitter;
 import com.google.common.collect.ImmutableList;
+import com.google.errorprone.annotations.CanIgnoreReturnValue;
 import com.google.errorprone.annotations.Immutable;
 import com.google.thirdparty.publicsuffix.PublicSuffixPatterns;
 import com.google.thirdparty.publicsuffix.PublicSuffixType;
 import java.util.List;
-import org.checkerframework.checker.nullness.qual.Nullable;
+import javax.annotation.CheckForNull;
 
 /**
  * An immutable well-formed internet domain name, such as {@code com} or {@code foo.co.uk}. Only
@@ -71,9 +71,9 @@
  * @author Catherine Berry
  * @since 5.0
  */
-@Beta
 @GwtCompatible(emulated = true)
 @Immutable
+@ElementTypesAreNonnullByDefault
 public final class InternetDomainName {
 
   private static final CharMatcher DOTS_MATCHER = CharMatcher.anyOf(".\u3002\uFF0E\uFF61");
@@ -162,7 +162,7 @@ public final class InternetDomainName {
    * Otherwise, it finds the first suffix of any type.
    */
   private int findSuffixOfType(Optional<PublicSuffixType> desiredType) {
-    final int partsSize = parts.size();
+    int partsSize = parts.size();
 
     for (int i = 0; i < partsSize; i++) {
       String ancestorName = DOT_JOINER.join(parts.subList(i, partsSize));
@@ -205,6 +205,7 @@ private int findSuffixOfType(Optional<PublicSuffixType> desiredType) {
    *     {@link #isValid}
    * @since 10.0 (previously named {@code fromLenient})
    */
+  @CanIgnoreReturnValue // TODO(b/219820829): consider removing
   public static InternetDomainName from(String domain) {
     return new InternetDomainName(checkNotNull(domain));
   }
@@ -216,7 +217,7 @@ public static InternetDomainName from(String domain) {
    * @return Is the domain name syntactically valid?
    */
   private static boolean validateSyntax(List<String> parts) {
-    final int lastIndex = parts.size() - 1;
+    int lastIndex = parts.size() - 1;
 
     // Validate the last part specially, as it has different syntax rules.
 
@@ -353,6 +354,7 @@ public boolean hasPublicSuffix() {
    *
    * @since 6.0
    */
+  @CheckForNull
   public InternetDomainName publicSuffix() {
     return hasPublicSuffix() ? ancestor(publicSuffixIndex) : null;
   }
@@ -461,6 +463,7 @@ public boolean hasRegistrySuffix() {
    *
    * @since 23.3
    */
+  @CheckForNull
   public InternetDomainName registrySuffix() {
     return hasRegistrySuffix() ? ancestor(registrySuffixIndex) : null;
   }
@@ -581,7 +584,7 @@ public InternetDomainName child(String leftParts) {
    */
   public static boolean isValid(String name) {
     try {
-      from(name);
+      InternetDomainName unused = from(name);
       return true;
     } catch (IllegalArgumentException e) {
       return false;
@@ -621,7 +624,7 @@ public String toString() {
    * version of the same domain name would not be considered equal.
    */
   @Override
-  public boolean equals(@Nullable Object object) {
+  public boolean equals(@CheckForNull Object object) {
     if (object == this) {
       return true;
     }
diff --git a/guava/src/com/google/common/net/MediaType.java b/guava/src/com/google/common/net/MediaType.java
index f52f24e2ec2c..a713d0b17ae5 100644
--- a/guava/src/com/google/common/net/MediaType.java
+++ b/guava/src/com/google/common/net/MediaType.java
@@ -21,11 +21,9 @@
 import static com.google.common.base.Preconditions.checkNotNull;
 import static com.google.common.base.Preconditions.checkState;
 
-import com.google.common.annotations.Beta;
 import com.google.common.annotations.GwtCompatible;
 import com.google.common.base.Ascii;
 import com.google.common.base.CharMatcher;
-import com.google.common.base.Function;
 import com.google.common.base.Joiner;
 import com.google.common.base.Joiner.MapJoiner;
 import com.google.common.base.MoreObjects;
@@ -37,15 +35,15 @@
 import com.google.common.collect.Maps;
 import com.google.common.collect.Multimap;
 import com.google.common.collect.Multimaps;
+import com.google.errorprone.annotations.CanIgnoreReturnValue;
 import com.google.errorprone.annotations.Immutable;
 import com.google.errorprone.annotations.concurrent.LazyInit;
 import java.nio.charset.Charset;
 import java.nio.charset.IllegalCharsetNameException;
 import java.nio.charset.UnsupportedCharsetException;
-import java.util.Collection;
 import java.util.Map;
 import java.util.Map.Entry;
-import org.checkerframework.checker.nullness.qual.Nullable;
+import javax.annotation.CheckForNull;
 
 /**
  * Represents an <a href="http://en.wikipedia.org/wiki/Internet_media_type">Internet Media Type</a>
@@ -72,9 +70,9 @@
  * @since 12.0
  * @author Gregory Kick
  */
-@Beta
 @GwtCompatible
 @Immutable
+@ElementTypesAreNonnullByDefault
 public final class MediaType {
   private static final String CHARSET_ATTRIBUTE = "charset";
   private static final ImmutableListMultimap<String, String> UTF_8_CONSTANT_PARAMETERS =
@@ -763,11 +761,11 @@ private static MediaType addKnownType(MediaType mediaType) {
   private final String subtype;
   private final ImmutableListMultimap<String, String> parameters;
 
-  @LazyInit private String toString;
+  @LazyInit @CheckForNull private String toString;
 
   @LazyInit private int hashCode;
 
-  @LazyInit private Optional<Charset> parsedCharset;
+  @LazyInit @CheckForNull private Optional<Charset> parsedCharset;
 
   private MediaType(String type, String subtype, ImmutableListMultimap<String, String> parameters) {
     this.type = type;
@@ -791,14 +789,7 @@ public ImmutableListMultimap<String, String> parameters() {
   }
 
   private Map<String, ImmutableMultiset<String>> parametersAsMap() {
-    return Maps.transformValues(
-        parameters.asMap(),
-        new Function<Collection<String>, ImmutableMultiset<String>>() {
-          @Override
-          public ImmutableMultiset<String> apply(Collection<String> input) {
-            return ImmutableMultiset.copyOf(input);
-          }
-        });
+    return Maps.transformValues(parameters.asMap(), ImmutableMultiset::copyOf);
   }
 
   /**
@@ -1048,6 +1039,7 @@ private static String normalizeParameterValue(String attribute, String value) {
    *
    * @throws IllegalArgumentException if the input is not parsable
    */
+  @CanIgnoreReturnValue // TODO(b/219820829): consider removing
   public static MediaType parse(String input) {
     checkNotNull(input);
     Tokenizer tokenizer = new Tokenizer(input);
@@ -1062,7 +1054,7 @@ public static MediaType parse(String input) {
         tokenizer.consumeTokenIfPresent(LINEAR_WHITE_SPACE);
         String attribute = tokenizer.consumeToken(TOKEN_MATCHER);
         tokenizer.consumeCharacter('=');
-        final String value;
+        String value;
         if ('"' == tokenizer.previewChar()) {
           tokenizer.consumeCharacter('"');
           StringBuilder valueBuilder = new StringBuilder();
@@ -1095,6 +1087,7 @@ private static final class Tokenizer {
       this.input = input;
     }
 
+    @CanIgnoreReturnValue
     String consumeTokenIfPresent(CharMatcher matcher) {
       checkState(hasMore());
       int startPosition = position;
@@ -1117,6 +1110,7 @@ char consumeCharacter(CharMatcher matcher) {
       return c;
     }
 
+    @CanIgnoreReturnValue
     char consumeCharacter(char c) {
       checkState(hasMore());
       checkState(previewChar() == c);
@@ -1135,7 +1129,7 @@ boolean hasMore() {
   }
 
   @Override
-  public boolean equals(@Nullable Object obj) {
+  public boolean equals(@CheckForNull Object obj) {
     if (obj == this) {
       return true;
     } else if (obj instanceof MediaType) {
@@ -1184,14 +1178,10 @@ private String computeToString() {
       Multimap<String, String> quotedParameters =
           Multimaps.transformValues(
               parameters,
-              new Function<String, String>() {
-                @Override
-                public String apply(String value) {
-                  return (TOKEN_MATCHER.matchesAllOf(value) && !value.isEmpty())
+              (String value) ->
+                  (TOKEN_MATCHER.matchesAllOf(value) && !value.isEmpty())
                       ? value
-                      : escapeAndQuote(value);
-                }
-              });
+                      : escapeAndQuote(value));
       PARAMETER_JOINER.appendTo(builder, quotedParameters.entries());
     }
     return builder.toString();
diff --git a/guava/src/com/google/common/net/ParametricNullness.java b/guava/src/com/google/common/net/ParametricNullness.java
new file mode 100644
index 000000000000..1ad2e27c0f4f
--- /dev/null
+++ b/guava/src/com/google/common/net/ParametricNullness.java
@@ -0,0 +1,52 @@
+/*
+ * Copyright (C) 2021 The Guava Authors
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package com.google.common.net;
+
+import static java.lang.annotation.ElementType.FIELD;
+import static java.lang.annotation.ElementType.METHOD;
+import static java.lang.annotation.ElementType.PARAMETER;
+import static java.lang.annotation.RetentionPolicy.RUNTIME;
+
+import com.google.common.annotations.GwtCompatible;
+import java.lang.annotation.Retention;
+import java.lang.annotation.Target;
+
+/**
+ * Marks a "top-level" type-variable usage as the closest we can get to "non-nullable when
+ * non-nullable; nullable when nullable" (like the Android <a
+ * href="https://android.googlesource.com/platform/libcore/+/master/luni/src/main/java/libcore/util/NullFromTypeParam.java">{@code
+ * NullFromTypeParam}</a>).
+ *
+ * <p>Consumers of this annotation include:
+ *
+ * <ul>
+ *   <li>Kotlin, for which it makes the type-variable usage (a) a Kotlin platform type when the type
+ *       argument is non-nullable and (b) nullable when the type argument is nullable. We use this
+ *       to "undo" {@link ElementTypesAreNonnullByDefault}.
+ *   <li><a href="https://developers.google.com/j2objc">J2ObjC</a>
+ *   <li>{@code NullPointerTester}, at least in the Android backport (where the type-use annotations
+ *       {@code NullPointerTester} would need are not available) and in case of <a
+ *       href="https://bugs.openjdk.java.net/browse/JDK-8202469">JDK-8202469</a>
+ * </ul>
+ *
+ */
+@GwtCompatible
+@Retention(RUNTIME)
+@Target({FIELD, METHOD, PARAMETER})
+@javax.annotation.meta.TypeQualifierNickname
+@javax.annotation.Nonnull(when = javax.annotation.meta.When.UNKNOWN)
+@interface ParametricNullness {}
diff --git a/guava/src/com/google/common/net/PercentEscaper.java b/guava/src/com/google/common/net/PercentEscaper.java
index 554d04d78d7a..92901473123c 100644
--- a/guava/src/com/google/common/net/PercentEscaper.java
+++ b/guava/src/com/google/common/net/PercentEscaper.java
@@ -16,9 +16,9 @@
 
 import static com.google.common.base.Preconditions.checkNotNull;
 
-import com.google.common.annotations.Beta;
 import com.google.common.annotations.GwtCompatible;
 import com.google.common.escape.UnicodeEscaper;
+import javax.annotation.CheckForNull;
 
 /**
  * A {@code UnicodeEscaper} that escapes some set of Java characters using a UTF-8 based percent
@@ -49,8 +49,8 @@
  * @author David Beaumont
  * @since 15.0
  */
-@Beta
 @GwtCompatible
+@ElementTypesAreNonnullByDefault
 public final class PercentEscaper extends UnicodeEscaper {
 
   // In some escapers spaces are escaped to '+'
@@ -155,6 +155,7 @@ public String escape(String s) {
 
   /** Escapes the given Unicode code point in UTF-8. */
   @Override
+  @CheckForNull
   protected char[] escape(int cp) {
     // We should never get negative values here but if we do it will throw an
     // IndexOutOfBoundsException, so at least it will get spotted.
diff --git a/guava/src/com/google/common/net/UrlEscapers.java b/guava/src/com/google/common/net/UrlEscapers.java
index 28da2e337753..c7e15efc6d91 100644
--- a/guava/src/com/google/common/net/UrlEscapers.java
+++ b/guava/src/com/google/common/net/UrlEscapers.java
@@ -29,6 +29,7 @@
  * @since 15.0
  */
 @GwtCompatible
+@ElementTypesAreNonnullByDefault
 public final class UrlEscapers {
   private UrlEscapers() {}
 
diff --git a/guava/src/com/google/common/net/package-info.java b/guava/src/com/google/common/net/package-info.java
index d9db26637974..d55642d9431b 100644
--- a/guava/src/com/google/common/net/package-info.java
+++ b/guava/src/com/google/common/net/package-info.java
@@ -21,7 +21,9 @@
  *
  * @author Craig Berry
  */
+@CheckReturnValue
 @ParametersAreNonnullByDefault
 package com.google.common.net;
 
+import com.google.errorprone.annotations.CheckReturnValue;
 import javax.annotation.ParametersAreNonnullByDefault;
diff --git a/guava/src/com/google/common/primitives/Booleans.java b/guava/src/com/google/common/primitives/Booleans.java
index 66a4f2a9cbe8..46b21c240b69 100644
--- a/guava/src/com/google/common/primitives/Booleans.java
+++ b/guava/src/com/google/common/primitives/Booleans.java
@@ -29,6 +29,7 @@
 import java.util.Comparator;
 import java.util.List;
 import java.util.RandomAccess;
+import javax.annotation.CheckForNull;
 import org.checkerframework.checker.index.qual.IndexFor;
 import org.checkerframework.checker.index.qual.IndexOrHigh;
 import org.checkerframework.checker.index.qual.IndexOrLow;
@@ -40,6 +41,7 @@
 import org.checkerframework.checker.index.qual.HasSubsequence;
 import org.checkerframework.checker.index.qual.LessThan;
 import org.checkerframework.checker.nullness.qual.Nullable;
+import org.checkerframework.checker.signedness.qual.UnknownSignedness;
 import org.checkerframework.common.value.qual.MinLen;
 
 /**
@@ -53,6 +55,7 @@
  * @since 1.0
  */
 @GwtCompatible
+@ElementTypesAreNonnullByDefault
 public final class Booleans {
   private Booleans() {}
 
@@ -193,7 +196,7 @@ public static boolean contains(boolean[] array, boolean target) {
    * @param array the array to search for the sequence {@code target}
    * @param target the array to search for as a sub-sequence of {@code array}
    */
-  @SuppressWarnings("substringindex:return.type.incompatible") // https://github.com/kelloggm/checker-framework/issues/206 https://github.com/kelloggm/checker-framework/issues/207 https://github.com/kelloggm/checker-framework/issues/208
+  @SuppressWarnings("substringindex:return") // https://github.com/kelloggm/checker-framework/issues/206, 207 and 208
   public static @LTEqLengthOf("#1") @SubstringIndexFor(value = "#1", offset = "#2.length - 1") int indexOf(boolean[] array, boolean[] target) {
     checkNotNull(array, "array");
     checkNotNull(target, "target");
@@ -249,7 +252,7 @@ public static boolean contains(boolean[] array, boolean target) {
    * pos is increased the same way as length, so pos points to a valid
    * range of length array.length in result.
    */
-  @SuppressWarnings("upperbound:argument.type.incompatible") // sum of lengths
+  @SuppressWarnings("upperbound:argument") // sum of lengths
   public static boolean[] concat(boolean[]... arrays) {
     int length = 0;
     for (boolean[] array : arrays) {
@@ -430,17 +433,15 @@ public Boolean get(@IndexFor("this") int index) {
     }
 
     @Override
-    public boolean contains(Object target) {
+    public boolean contains(@CheckForNull @UnknownSignedness Object target) {
       // Overridden to prevent a ton of boxing
       return (target instanceof Boolean)
           && Booleans.indexOf(array, (Boolean) target, start, end) != -1;
     }
 
     @Override
-    @SuppressWarnings({
-            "lowerbound:return.type.incompatible" // needs https://github.com/kelloggm/checker-framework/issues/227 on static lastIndexOf method
-    })
-    public @IndexOrLow("this") int indexOf(Object target) {
+    @SuppressWarnings("lowerbound:return")
+    public @IndexOrLow("this") int indexOf(@CheckForNull @UnknownSignedness Object target) {
       // Overridden to prevent a ton of boxing
       if (target instanceof Boolean) {
         int i = Booleans.indexOf(array, (Boolean) target, start, end);
@@ -452,10 +453,8 @@ public boolean contains(Object target) {
     }
 
     @Override
-    @SuppressWarnings({
-            "lowerbound:return.type.incompatible" // needs https://github.com/kelloggm/checker-framework/issues/227 on static lastIndexOf method
-    })
-    public @IndexOrLow("this") int lastIndexOf(Object target) {
+    @SuppressWarnings("lowerbound:return")
+    public @IndexOrLow("this") int lastIndexOf(@CheckForNull @UnknownSignedness Object target) {
       // Overridden to prevent a ton of boxing
       if (target instanceof Boolean) {
         int i = Booleans.lastIndexOf(array, (Boolean) target, start, end);
@@ -487,7 +486,7 @@ public List<Boolean> subList(@IndexOrHigh("this") int fromIndex, @IndexOrHigh("t
     }
 
     @Override
-    public boolean equals(@Nullable Object object) {
+    public boolean equals(@CheckForNull @UnknownSignedness Object object) {
       if (object == this) {
         return true;
       }
diff --git a/guava/src/com/google/common/primitives/Bytes.java b/guava/src/com/google/common/primitives/Bytes.java
index f7cdce1e7eef..d8df5407f606 100644
--- a/guava/src/com/google/common/primitives/Bytes.java
+++ b/guava/src/com/google/common/primitives/Bytes.java
@@ -27,6 +27,7 @@
 import java.util.Collections;
 import java.util.List;
 import java.util.RandomAccess;
+import javax.annotation.CheckForNull;
 import org.checkerframework.checker.index.qual.IndexFor;
 import org.checkerframework.checker.index.qual.IndexOrHigh;
 import org.checkerframework.checker.index.qual.IndexOrLow;
@@ -55,6 +56,7 @@
 // TODO(kevinb): how to prevent warning on UnsignedBytes when building GWT
 // javadoc?
 @GwtCompatible
+@ElementTypesAreNonnullByDefault
 public final class Bytes {
   private Bytes() {}
 
@@ -119,7 +121,7 @@ public static boolean contains(byte[] array, byte target) {
    * @param array the array to search for the sequence {@code target}
    * @param target the array to search for as a sub-sequence of {@code array}
    */
-  @SuppressWarnings("substringindex:return.type.incompatible") // https://github.com/kelloggm/checker-framework/issues/206 https://github.com/kelloggm/checker-framework/issues/207 https://github.com/kelloggm/checker-framework/issues/208
+  @SuppressWarnings("substringindex:return") // https://github.com/kelloggm/checker-framework/issues/206, 207 and 208
   public static @LTEqLengthOf("#1") @SubstringIndexFor(value = "#1", offset = "#2.length - 1") int indexOf(byte[] array, byte[] target) {
     checkNotNull(array, "array");
     checkNotNull(target, "target");
@@ -174,7 +176,7 @@ public static boolean contains(byte[] array, byte target) {
    * pos is increased the same way as length, so pos points to a valid
    * range of length array.length in result.
    */
-  @SuppressWarnings("upperbound:argument.type.incompatible") // sum of lengths
+  @SuppressWarnings("upperbound:argument") // sum of lengths
   public static byte[] concat(byte[]... arrays) {
     int length = 0;
     for (byte[] array : arrays) {
@@ -292,15 +294,14 @@ public Byte get(@IndexFor("this") int index) {
     }
 
     @Override
-    public boolean contains(Object target) {
+    public boolean contains(@CheckForNull Object target) {
       // Overridden to prevent a ton of boxing
       return (target instanceof Byte) && Bytes.indexOf(array, (Byte) target, start, end) != -1;
     }
 
     @Override
-    @SuppressWarnings(
-            "lowerbound:return.type.incompatible") // needs https://github.com/kelloggm/checker-framework/issues/227 on static indexOf method
-    public @IndexOrLow("this") int indexOf(Object target) {
+    @SuppressWarnings("index:return")
+    public @IndexOrLow("this") int indexOf(@CheckForNull Object target) {
       // Overridden to prevent a ton of boxing
       if (target instanceof Byte) {
         int i = Bytes.indexOf(array, (Byte) target, start, end);
@@ -312,9 +313,8 @@ public boolean contains(Object target) {
     }
 
     @Override
-    @SuppressWarnings(
-            "lowerbound:return.type.incompatible") // needs https://github.com/kelloggm/checker-framework/issues/227 on static indexOf method
-    public @IndexOrLow("this") int lastIndexOf(Object target) {
+    @SuppressWarnings("index:return")
+    public @IndexOrLow("this") int lastIndexOf(@CheckForNull Object target) {
       // Overridden to prevent a ton of boxing
       if (target instanceof Byte) {
         int i = Bytes.lastIndexOf(array, (Byte) target, start, end);
@@ -346,7 +346,7 @@ public List<Byte> subList(@IndexOrHigh("this") int fromIndex, @IndexOrHigh("this
     }
 
     @Override
-    public boolean equals(@Nullable Object object) {
+    public boolean equals(@CheckForNull Object object) {
       if (object == this) {
         return true;
       }
diff --git a/guava/src/com/google/common/primitives/Chars.java b/guava/src/com/google/common/primitives/Chars.java
index 5c63eab40f30..42af35791d77 100644
--- a/guava/src/com/google/common/primitives/Chars.java
+++ b/guava/src/com/google/common/primitives/Chars.java
@@ -30,6 +30,7 @@
 import java.util.Comparator;
 import java.util.List;
 import java.util.RandomAccess;
+import javax.annotation.CheckForNull;
 import org.checkerframework.checker.index.qual.IndexFor;
 import org.checkerframework.checker.index.qual.IndexOrHigh;
 import org.checkerframework.checker.index.qual.IndexOrLow;
@@ -58,6 +59,7 @@
  * @since 1.0
  */
 @GwtCompatible(emulated = true)
+@ElementTypesAreNonnullByDefault
 public final class Chars {
   private Chars() {}
 
@@ -177,7 +179,7 @@ public static boolean contains(char[] array, char target) {
    * @param array the array to search for the sequence {@code target}
    * @param target the array to search for as a sub-sequence of {@code array}
    */
-  @SuppressWarnings("substringindex:return.type.incompatible") // https://github.com/kelloggm/checker-framework/issues/206 https://github.com/kelloggm/checker-framework/issues/207 https://github.com/kelloggm/checker-framework/issues/208
+  @SuppressWarnings("substringindex:return") // https://github.com/kelloggm/checker-framework/issues/206, 207 and 208
   public static @LTEqLengthOf("#1") @SubstringIndexFor(value = "#1", offset="#2.length - 1") int indexOf(char[] array, char[] target) {
     checkNotNull(array, "array");
     checkNotNull(target, "target");
@@ -289,7 +291,7 @@ public static char constrainToRange(char value, char min, char max) {
    * pos is increased the same way as length, so pos points to a valid
    * range of length array.length in result.
    */
-  @SuppressWarnings("upperbound:argument.type.incompatible") // sum of lengths
+  @SuppressWarnings("upperbound:argument") // sum of lengths
   public static char[] concat(char[]... arrays) {
     int length = 0;
     for (char[] array : arrays) {
@@ -565,16 +567,15 @@ public Character get(@IndexFor("this") int index) {
     }
 
     @Override
-    public boolean contains(Object target) {
+    public boolean contains(@CheckForNull Object target) {
       // Overridden to prevent a ton of boxing
       return (target instanceof Character)
           && Chars.indexOf(array, (Character) target, start, end) != -1;
     }
 
     @Override
-    @SuppressWarnings(
-            "lowerbound:return.type.incompatible") // needs https://github.com/kelloggm/checker-framework/issues/227 on static indexOf method
-    public @IndexOrLow("this") int indexOf(Object target) {
+    @SuppressWarnings("lowerbound:return")
+    public @IndexOrLow("this") int indexOf(@CheckForNull Object target) {
       // Overridden to prevent a ton of boxing
       if (target instanceof Character) {
         int i = Chars.indexOf(array, (Character) target, start, end);
@@ -586,9 +587,8 @@ public boolean contains(Object target) {
     }
 
     @Override
-    @SuppressWarnings(
-            "lowerbound:return.type.incompatible") // needs https://github.com/kelloggm/checker-framework/issues/227 on static indexOf method
-    public @IndexOrLow("this") int lastIndexOf(Object target) {
+    @SuppressWarnings("lowerbound:return")
+    public @IndexOrLow("this") int lastIndexOf(@CheckForNull Object target) {
       // Overridden to prevent a ton of boxing
       if (target instanceof Character) {
         int i = Chars.lastIndexOf(array, (Character) target, start, end);
@@ -620,7 +620,7 @@ public List<Character> subList(@IndexOrHigh("this") int fromIndex, @IndexOrHigh(
     }
 
     @Override
-    public boolean equals(@Nullable Object object) {
+    public boolean equals(@CheckForNull Object object) {
       if (object == this) {
         return true;
       }
diff --git a/guava/src/com/google/common/primitives/Doubles.java b/guava/src/com/google/common/primitives/Doubles.java
index cacc782e3f6f..25002829d719 100644
--- a/guava/src/com/google/common/primitives/Doubles.java
+++ b/guava/src/com/google/common/primitives/Doubles.java
@@ -36,6 +36,7 @@
 import java.util.RandomAccess;
 import java.util.Spliterator;
 import java.util.Spliterators;
+import javax.annotation.CheckForNull;
 import org.checkerframework.checker.index.qual.IndexFor;
 import org.checkerframework.checker.index.qual.IndexOrHigh;
 import org.checkerframework.checker.index.qual.IndexOrLow;
@@ -60,6 +61,7 @@
  * @since 1.0
  */
 @GwtCompatible(emulated = true)
+@ElementTypesAreNonnullByDefault
 public final class Doubles extends DoublesMethodsForWeb {
   private Doubles() {}
 
@@ -170,7 +172,7 @@ public static boolean contains(double[] array, double target) {
    * @param array the array to search for the sequence {@code target}
    * @param target the array to search for as a sub-sequence of {@code array}
    */
-  @SuppressWarnings("substringindex:return.type.incompatible") // https://github.com/kelloggm/checker-framework/issues/206 https://github.com/kelloggm/checker-framework/issues/207 https://github.com/kelloggm/checker-framework/issues/208
+  @SuppressWarnings("substringindex:return") // https://github.com/kelloggm/checker-framework/issues/206, 207 and 208
   public static @LTEqLengthOf("#1") @SubstringIndexFor(value = "#1", offset="#2.length - 1") int indexOf(double[] array, double[] target) {
     checkNotNull(array, "array");
     checkNotNull(target, "target");
@@ -291,7 +293,7 @@ public static double constrainToRange(double value, double min, double max) {
    * pos is increased the same way as length, so pos points to a valid
    * range of length array.length in result.
    */
-  @SuppressWarnings("upperbound:argument.type.incompatible") // sum of lengths
+  @SuppressWarnings("upperbound:argument") // sum of lengths
   public static double[] concat(double[]... arrays) {
     int length = 0;
     for (double[] array : arrays) {
@@ -582,16 +584,15 @@ public Spliterator.OfDouble spliterator() {
     }
 
     @Override
-    public boolean contains(Object target) {
+    public boolean contains(@CheckForNull Object target) {
       // Overridden to prevent a ton of boxing
       return (target instanceof Double)
           && Doubles.indexOf(array, (Double) target, start, end) != -1;
     }
 
     @Override
-    @SuppressWarnings(
-            "lowerbound:return.type.incompatible") // needs https://github.com/kelloggm/checker-framework/issues/227 on static indexOf method
-    public @IndexOrLow("this") int indexOf(Object target) {
+    @SuppressWarnings("lowerbound:return")
+    public @IndexOrLow("this") int indexOf(@CheckForNull Object target) {
       // Overridden to prevent a ton of boxing
       if (target instanceof Double) {
         int i = Doubles.indexOf(array, (Double) target, start, end);
@@ -603,9 +604,8 @@ public boolean contains(Object target) {
     }
 
     @Override
-    @SuppressWarnings(
-            "lowerbound:return.type.incompatible") // needs https://github.com/kelloggm/checker-framework/issues/227 on static indexOf method
-    public @IndexOrLow("this")int lastIndexOf(Object target) {
+    @SuppressWarnings("lowerbound:return")
+    public @IndexOrLow("this")int lastIndexOf(@CheckForNull Object target) {
       // Overridden to prevent a ton of boxing
       if (target instanceof Double) {
         int i = Doubles.lastIndexOf(array, (Double) target, start, end);
@@ -637,7 +637,7 @@ public List<Double> subList(@IndexOrHigh("this") int fromIndex, @IndexOrHigh("th
     }
 
     @Override
-    public boolean equals(@Nullable Object object) {
+    public boolean equals(@CheckForNull Object object) {
       if (object == this) {
         return true;
       }
@@ -736,7 +736,8 @@ public String toString() {
    */
   @Beta
   @GwtIncompatible // regular expressions
-  public static @Nullable Double tryParse(String string) {
+  @CheckForNull
+  public static Double tryParse(String string) {
     if (FLOATING_POINT_PATTERN.matcher(string).matches()) {
       // TODO(lowasser): could be potentially optimized, but only with
       // extensive testing
diff --git a/guava/src/com/google/common/primitives/DoublesMethodsForWeb.java b/guava/src/com/google/common/primitives/DoublesMethodsForWeb.java
index 04d96512211d..949cbe0f5a6b 100644
--- a/guava/src/com/google/common/primitives/DoublesMethodsForWeb.java
+++ b/guava/src/com/google/common/primitives/DoublesMethodsForWeb.java
@@ -21,4 +21,5 @@
  * version.
  */
 @GwtCompatible(emulated = true)
+@ElementTypesAreNonnullByDefault
 abstract class DoublesMethodsForWeb {}
diff --git a/guava/src/com/google/common/primitives/ElementTypesAreNonnullByDefault.java b/guava/src/com/google/common/primitives/ElementTypesAreNonnullByDefault.java
new file mode 100644
index 000000000000..44f6869c7cda
--- /dev/null
+++ b/guava/src/com/google/common/primitives/ElementTypesAreNonnullByDefault.java
@@ -0,0 +1,41 @@
+/*
+ * Copyright (C) 2021 The Guava Authors
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package com.google.common.primitives;
+
+import static java.lang.annotation.ElementType.FIELD;
+import static java.lang.annotation.ElementType.METHOD;
+import static java.lang.annotation.ElementType.PARAMETER;
+import static java.lang.annotation.ElementType.TYPE;
+import static java.lang.annotation.RetentionPolicy.RUNTIME;
+
+import com.google.common.annotations.GwtCompatible;
+import java.lang.annotation.Retention;
+import java.lang.annotation.Target;
+import javax.annotation.Nonnull;
+import javax.annotation.meta.TypeQualifierDefault;
+
+/**
+ * Marks all "top-level" types as non-null in a way that is recognized by Kotlin. Note that this
+ * unfortunately includes type-variable usages, so we also provide {@link ParametricNullness} to
+ * "undo" it as best we can.
+ */
+@GwtCompatible
+@Retention(RUNTIME)
+@Target(TYPE)
+@TypeQualifierDefault({FIELD, METHOD, PARAMETER})
+@Nonnull
+@interface ElementTypesAreNonnullByDefault {}
diff --git a/guava/src/com/google/common/primitives/Floats.java b/guava/src/com/google/common/primitives/Floats.java
index 2a654708fcd2..629892fbfa4e 100644
--- a/guava/src/com/google/common/primitives/Floats.java
+++ b/guava/src/com/google/common/primitives/Floats.java
@@ -34,6 +34,7 @@
 import java.util.Comparator;
 import java.util.List;
 import java.util.RandomAccess;
+import javax.annotation.CheckForNull;
 import org.checkerframework.checker.index.qual.IndexFor;
 import org.checkerframework.checker.index.qual.IndexOrHigh;
 import org.checkerframework.checker.index.qual.IndexOrLow;
@@ -58,6 +59,7 @@
  * @since 1.0
  */
 @GwtCompatible(emulated = true)
+@ElementTypesAreNonnullByDefault
 public final class Floats extends FloatsMethodsForWeb {
   private Floats() {}
 
@@ -165,7 +167,7 @@ public static boolean contains(float[] array, float target) {
    * @param array the array to search for the sequence {@code target}
    * @param target the array to search for as a sub-sequence of {@code array}
    */
-  @SuppressWarnings("substringindex:return.type.incompatible") // https://github.com/kelloggm/checker-framework/issues/206 https://github.com/kelloggm/checker-framework/issues/207 https://github.com/kelloggm/checker-framework/issues/208
+  @SuppressWarnings("substringindex:return") // https://github.com/kelloggm/checker-framework/issues/206, 207 and 208
   public static @LTEqLengthOf("#1") @SubstringIndexFor(value = "#1", offset="#2.length - 1") int indexOf(float[] array, float[] target) {
     checkNotNull(array, "array");
     checkNotNull(target, "target");
@@ -286,7 +288,7 @@ public static float constrainToRange(float value, float min, float max) {
    * pos is increased the same way as length, so pos points to a valid
    * range of length array.length in result.
    */
-  @SuppressWarnings("upperbound:argument.type.incompatible") // sum of lengths
+  @SuppressWarnings("upperbound:argument") // sum of lengths
   public static float[] concat(float[]... arrays) {
     int length = 0;
     for (float[] array : arrays) {
@@ -569,15 +571,14 @@ public Float get(@IndexFor("this") int index) {
     }
 
     @Override
-    public boolean contains(Object target) {
+    public boolean contains(@CheckForNull Object target) {
       // Overridden to prevent a ton of boxing
       return (target instanceof Float) && Floats.indexOf(array, (Float) target, start, end) != -1;
     }
 
     @Override
-    @SuppressWarnings(
-            "lowerbound:return.type.incompatible") // needs https://github.com/kelloggm/checker-framework/issues/227 on static indexOf method
-    public @IndexOrLow("this") int indexOf(Object target) {
+    @SuppressWarnings("lowerbound:return")
+    public @IndexOrLow("this") int indexOf(@CheckForNull Object target) {
       // Overridden to prevent a ton of boxing
       if (target instanceof Float) {
         int i = Floats.indexOf(array, (Float) target, start, end);
@@ -589,9 +590,8 @@ public boolean contains(Object target) {
     }
 
     @Override
-    @SuppressWarnings(
-            "lowerbound:return.type.incompatible") // needs https://github.com/kelloggm/checker-framework/issues/227 on static indexOf method
-    public @IndexOrLow("this") int lastIndexOf(Object target) {
+    @SuppressWarnings("lowerbound:return")
+    public @IndexOrLow("this") int lastIndexOf(@CheckForNull Object target) {
       // Overridden to prevent a ton of boxing
       if (target instanceof Float) {
         int i = Floats.lastIndexOf(array, (Float) target, start, end);
@@ -623,7 +623,7 @@ public List<Float> subList(@IndexOrHigh("this") int fromIndex, @IndexOrHigh("thi
     }
 
     @Override
-    public boolean equals(@Nullable Object object) {
+    public boolean equals(@CheckForNull Object object) {
       if (object == this) {
         return true;
       }
@@ -688,7 +688,8 @@ float[] toFloatArray() {
    */
   @Beta
   @GwtIncompatible // regular expressions
-  public static @Nullable Float tryParse(String string) {
+  @CheckForNull
+  public static Float tryParse(String string) {
     if (Doubles.FLOATING_POINT_PATTERN.matcher(string).matches()) {
       // TODO(lowasser): could be potentially optimized, but only with
       // extensive testing
diff --git a/guava/src/com/google/common/primitives/FloatsMethodsForWeb.java b/guava/src/com/google/common/primitives/FloatsMethodsForWeb.java
index acdb42f275b1..801e2f3ef110 100644
--- a/guava/src/com/google/common/primitives/FloatsMethodsForWeb.java
+++ b/guava/src/com/google/common/primitives/FloatsMethodsForWeb.java
@@ -21,4 +21,5 @@
  * version.
  */
 @GwtCompatible(emulated = true)
+@ElementTypesAreNonnullByDefault
 abstract class FloatsMethodsForWeb {}
diff --git a/guava/src/com/google/common/primitives/ImmutableDoubleArray.java b/guava/src/com/google/common/primitives/ImmutableDoubleArray.java
index b0b8985f226f..665bc539d18c 100644
--- a/guava/src/com/google/common/primitives/ImmutableDoubleArray.java
+++ b/guava/src/com/google/common/primitives/ImmutableDoubleArray.java
@@ -33,6 +33,7 @@
 import java.util.Spliterators;
 import java.util.function.DoubleConsumer;
 import java.util.stream.DoubleStream;
+import javax.annotation.CheckForNull;
 import org.checkerframework.checker.index.qual.EnsuresLTLengthOf;
 import org.checkerframework.checker.index.qual.EnsuresLTLengthOfIf;
 import org.checkerframework.checker.index.qual.GTENegativeOne;
@@ -100,6 +101,7 @@
 @Beta
 @GwtCompatible
 @Immutable
+@ElementTypesAreNonnullByDefault
 public final class ImmutableDoubleArray implements Serializable {
   private static final ImmutableDoubleArray EMPTY = new ImmutableDoubleArray(new double[0]);
 
@@ -313,7 +315,7 @@ public Builder addAll(DoubleStream stream) {
        * count is @LTLengthOf(value="array",offset="values.length()-1"), which implies
        * values.length() is @LTLengthOf(value="array",offset="count-1")
        */
-      "upperbound:argument.type.incompatible" // LTLengthOf inversion
+      "upperbound:argument" // LTLengthOf inversion
     )
     public Builder addAll(ImmutableDoubleArray values) {
       ensureRoomFor(values.length());
@@ -331,8 +333,7 @@ public Builder addAll(ImmutableDoubleArray values) {
      *   https://github.com/kelloggm/checker-framework/issues/158
      */
     @SuppressWarnings({
-      "upperbound:argument.type.incompatible", // https://github.com/kelloggm/checker-framework/issues/158
-      "contracts.postcondition.not.satisfied", // postcondition
+      "index:contracts.postcondition", // postcondition
     })
     @EnsuresLTLengthOf(value = {"count", "#1"}, targetValue = {"array", "array"}, offset = {"#1 - 1","count - 1"})
     private void ensureRoomFor(@NonNegative int numberToAdd) {
@@ -408,7 +409,7 @@ private ImmutableDoubleArray(double[] array, @IndexOrHigh("#1") @LessThan("#3 +
   }
 
   /** Returns {@code true} if there are no values in this array ({@link #length} is zero). */
-  @SuppressWarnings("contracts.conditional.postcondition.not.satisfied") // postcondition
+  @SuppressWarnings("index:contracts.conditional.postcondition") // postcondition
   @EnsuresLTLengthOfIf(result = false, expression = "start", targetValue = "array")
   public boolean isEmpty() {
     return end == start;
@@ -436,7 +437,7 @@ public double get(@IndexFor("this") int index) {
    * such index exists. Values are compared as if by {@link Double#equals}. Equivalent to {@code
    * asList().indexOf(target)}.
    */
-  @SuppressWarnings("lowerbound:return.type.incompatible") // https://github.com/kelloggm/checker-framework/issues/232
+  @SuppressWarnings("lowerbound:return") // https://github.com/kelloggm/checker-framework/issues/232
   public @IndexOrLow("this") int indexOf(double target) {
     for (int i = start; i < end; i++) {
       if (areEqual(array[i], target)) {
@@ -524,7 +525,7 @@ public List<Double> asList() {
   static class AsList extends AbstractList<Double> implements RandomAccess, Serializable {
     private final @SameLen("this") ImmutableDoubleArray parent;
 
-    @SuppressWarnings("samelen:assignment.type.incompatible") // SameLen("this") field
+    @SuppressWarnings("samelen:assignment") // SameLen("this") field
     private AsList(ImmutableDoubleArray parent) {
       this.parent = parent;
     }
@@ -542,17 +543,17 @@ public Double get(@IndexFor("this") int index) {
     }
 
     @Override
-    public boolean contains(Object target) {
+    public boolean contains(@CheckForNull Object target) {
       return indexOf(target) >= 0;
     }
 
     @Override
-    public @GTENegativeOne int indexOf(Object target) {
+    public @GTENegativeOne int indexOf(@CheckForNull Object target) {
       return target instanceof Double ? parent.indexOf((Double) target) : -1;
     }
 
     @Override
-    public @GTENegativeOne int lastIndexOf(Object target) {
+    public @GTENegativeOne int lastIndexOf(@CheckForNull Object target) {
       return target instanceof Double ? parent.lastIndexOf((Double) target) : -1;
     }
 
@@ -574,7 +575,7 @@ public Spliterator<Double> spliterator() {
      * therefore i is an index for parent.array
      */
     @SuppressWarnings("upperbound:array.access.unsafe.high") // index incremented in for-each over list of same length
-    public boolean equals(@Nullable Object object) {
+    public boolean equals(@CheckForNull Object object) {
       if (object instanceof AsList) {
         AsList that = (AsList) object;
         return this.parent.equals(that.parent);
@@ -614,7 +615,7 @@ public String toString() {
    * values as this one, in the same order. Values are compared as if by {@link Double#equals}.
    */
   @Override
-  public boolean equals(@Nullable Object object) {
+  public boolean equals(@CheckForNull Object object) {
     if (object == this) {
       return true;
     }
diff --git a/guava/src/com/google/common/primitives/ImmutableIntArray.java b/guava/src/com/google/common/primitives/ImmutableIntArray.java
index 1a8a1abc026e..939c6bd5ec38 100644
--- a/guava/src/com/google/common/primitives/ImmutableIntArray.java
+++ b/guava/src/com/google/common/primitives/ImmutableIntArray.java
@@ -33,6 +33,7 @@
 import java.util.Spliterators;
 import java.util.function.IntConsumer;
 import java.util.stream.IntStream;
+import javax.annotation.CheckForNull;
 import org.checkerframework.checker.index.qual.EnsuresLTLengthOf;
 import org.checkerframework.checker.index.qual.EnsuresLTLengthOfIf;
 import org.checkerframework.checker.index.qual.GTENegativeOne;
@@ -100,6 +101,7 @@
 @Beta
 @GwtCompatible
 @Immutable
+@ElementTypesAreNonnullByDefault
 public final class ImmutableIntArray implements Serializable {
   private static final ImmutableIntArray EMPTY = new ImmutableIntArray(new int[0]);
 
@@ -310,7 +312,7 @@ public Builder addAll(IntStream stream) {
          * count is @LTLengthOf(value="array",offset="values.length()-1"), which implies
          * values.length() is @LTLengthOf(value="array",offset="count-1")
          */
-        "upperbound:argument.type.incompatible" // LTLengthOf inversion
+        "upperbound:argument" // LTLengthOf inversion
       )
     public Builder addAll(ImmutableIntArray values) {
       ensureRoomFor(values.length());
@@ -328,8 +330,7 @@ public Builder addAll(ImmutableIntArray values) {
      *   https://github.com/kelloggm/checker-framework/issues/158
      */
     @SuppressWarnings({
-      "upperbound:argument.type.incompatible", // https://github.com/kelloggm/checker-framework/issues/158
-      "contracts.postcondition.not.satisfied", // postcondition
+      "index:contracts.postcondition", // postcondition
     })
     @EnsuresLTLengthOf(value = {"count", "#1"}, targetValue = {"array", "array"}, offset = {"#1 - 1","count - 1"})
     private void ensureRoomFor(@NonNegative int numberToAdd) {
@@ -405,7 +406,7 @@ private ImmutableIntArray(int[] array, @IndexOrHigh("#1") @LessThan("#3 + 1") in
   }
 
   /** Returns {@code true} if there are no values in this array ({@link #length} is zero). */
-  @SuppressWarnings("contracts.conditional.postcondition.not.satisfied") // postcondition
+  @SuppressWarnings("index:contracts.conditional.postcondition") // postcondition
   @EnsuresLTLengthOfIf(result = false, expression = "start", targetValue = "array")
   public boolean isEmpty() {
     return end == start;
@@ -432,7 +433,7 @@ public int get(@IndexFor("this") int index) {
    * Returns the smallest index for which {@link #get} returns {@code target}, or {@code -1} if no
    * such index exists. Equivalent to {@code asList().indexOf(target)}.
    */
-  @SuppressWarnings("lowerbound:return.type.incompatible") // https://github.com/kelloggm/checker-framework/issues/232
+  @SuppressWarnings("lowerbound:return") // https://github.com/kelloggm/checker-framework/issues/232
   public @IndexOrLow("this") int indexOf(int target) {
     for (int i = start; i < end; i++) {
       if (array[i] == target) {
@@ -519,7 +520,7 @@ public List<Integer> asList() {
   static class AsList extends AbstractList<Integer> implements RandomAccess, Serializable {
     private final @SameLen("this") ImmutableIntArray parent;
 
-    @SuppressWarnings("samelen:assignment.type.incompatible") // SameLen("this") field
+    @SuppressWarnings("samelen:assignment") // SameLen("this") field
     private AsList(ImmutableIntArray parent) {
       this.parent = parent;
     }
@@ -537,17 +538,17 @@ public Integer get(@IndexFor("this") int index) {
     }
 
     @Override
-    public boolean contains(Object target) {
+    public boolean contains(@CheckForNull Object target) {
       return indexOf(target) >= 0;
     }
 
     @Override
-    public @GTENegativeOne int indexOf(Object target) {
+    public @GTENegativeOne int indexOf(@CheckForNull Object target) {
       return target instanceof Integer ? parent.indexOf((Integer) target) : -1;
     }
 
     @Override
-    public @GTENegativeOne int lastIndexOf(Object target) {
+    public @GTENegativeOne int lastIndexOf(@CheckForNull Object target) {
       return target instanceof Integer ? parent.lastIndexOf((Integer) target) : -1;
     }
 
@@ -569,7 +570,7 @@ public Spliterator<Integer> spliterator() {
      * therefore i is an index for parent.array
      */
     @SuppressWarnings("upperbound:array.access.unsafe.high") // index incremented in for-each over list of same length
-    public boolean equals(@Nullable Object object) {
+    public boolean equals(@CheckForNull Object object) {
       if (object instanceof AsList) {
         AsList that = (AsList) object;
         return this.parent.equals(that.parent);
@@ -609,7 +610,7 @@ public String toString() {
    * values as this one, in the same order.
    */
   @Override
-  public boolean equals(@Nullable Object object) {
+  public boolean equals(@CheckForNull Object object) {
     if (object == this) {
       return true;
     }
diff --git a/guava/src/com/google/common/primitives/ImmutableLongArray.java b/guava/src/com/google/common/primitives/ImmutableLongArray.java
index 540c8a094276..62373067221e 100644
--- a/guava/src/com/google/common/primitives/ImmutableLongArray.java
+++ b/guava/src/com/google/common/primitives/ImmutableLongArray.java
@@ -33,6 +33,7 @@
 import java.util.Spliterators;
 import java.util.function.LongConsumer;
 import java.util.stream.LongStream;
+import javax.annotation.CheckForNull;
 import org.checkerframework.checker.index.qual.EnsuresLTLengthOf;
 import org.checkerframework.checker.index.qual.EnsuresLTLengthOfIf;
 import org.checkerframework.checker.index.qual.GTENegativeOne;
@@ -100,6 +101,7 @@
 @Beta
 @GwtCompatible
 @Immutable
+@ElementTypesAreNonnullByDefault
 public final class ImmutableLongArray implements Serializable {
   private static final ImmutableLongArray EMPTY = new ImmutableLongArray(new long[0]);
 
@@ -312,7 +314,7 @@ public Builder addAll(LongStream stream) {
          * count is @LTLengthOf(value="array",offset="values.length()-1"), which implies
          * values.length() is @LTLengthOf(value="array",offset="count-1")
          */
-        "upperbound:argument.type.incompatible" // LTLengthOf inversion
+        "upperbound:argument" // LTLengthOf inversion
       )
     public Builder addAll(ImmutableLongArray values) {
       ensureRoomFor(values.length());
@@ -330,8 +332,7 @@ public Builder addAll(ImmutableLongArray values) {
      *   https://github.com/kelloggm/checker-framework/issues/158
      */
     @SuppressWarnings({
-      "upperbound:argument.type.incompatible", // https://github.com/kelloggm/checker-framework/issues/158
-      "contracts.postcondition.not.satisfied", // postcondition
+      "index:contracts.postcondition", // postcondition
     })
     @EnsuresLTLengthOf(value = {"count", "#1"}, targetValue = {"array", "array"}, offset = {"#1 - 1","count - 1"})
     private void ensureRoomFor(@NonNegative int numberToAdd) {
@@ -407,7 +408,7 @@ private ImmutableLongArray(long[] array, @IndexOrHigh("#1") int start, @IndexOrH
   }
 
   /** Returns {@code true} if there are no values in this array ({@link #length} is zero). */
-  @SuppressWarnings("contracts.conditional.postcondition.not.satisfied") // postcondition
+  @SuppressWarnings("index:contracts.conditional.postcondition") // postcondition
   @EnsuresLTLengthOfIf(result = false, expression = "start", targetValue = "array")
   public boolean isEmpty() {
     return end == start;
@@ -434,7 +435,7 @@ public long get(@IndexFor("this") int index) {
    * Returns the smallest index for which {@link #get} returns {@code target}, or {@code -1} if no
    * such index exists. Equivalent to {@code asList().indexOf(target)}.
    */
-  @SuppressWarnings("lowerbound:return.type.incompatible") // https://github.com/kelloggm/checker-framework/issues/232
+  @SuppressWarnings("lowerbound:return") // https://github.com/kelloggm/checker-framework/issues/232
   public @IndexOrLow("this") int indexOf(long target) {
     for (int i = start; i < end; i++) {
       if (array[i] == target) {
@@ -521,7 +522,7 @@ public List<Long> asList() {
   static class AsList extends AbstractList<Long> implements RandomAccess, Serializable {
     private final @SameLen("this") ImmutableLongArray parent;
 
-    @SuppressWarnings("samelen:assignment.type.incompatible") // https://github.com/kelloggm/checker-framework/issues/213
+    @SuppressWarnings("samelen:assignment") // https://github.com/kelloggm/checker-framework/issues/213
     private AsList(ImmutableLongArray parent) {
       this.parent = parent;
     }
@@ -539,17 +540,17 @@ public Long get(@IndexFor("this") int index) {
     }
 
     @Override
-    public boolean contains(Object target) {
+    public boolean contains(@CheckForNull Object target) {
       return indexOf(target) >= 0;
     }
 
     @Override
-    public @GTENegativeOne int indexOf(Object target) {
+    public @GTENegativeOne int indexOf(@CheckForNull Object target) {
       return target instanceof Long ? parent.indexOf((Long) target) : -1;
     }
 
     @Override
-    public @GTENegativeOne int lastIndexOf(Object target) {
+    public @GTENegativeOne int lastIndexOf(@CheckForNull Object target) {
       return target instanceof Long ? parent.lastIndexOf((Long) target) : -1;
     }
 
@@ -571,7 +572,7 @@ public Spliterator<Long> spliterator() {
      * therefore i is an index for parent.array
      */
     @SuppressWarnings("upperbound:array.access.unsafe.high") // index incremented in for-each over list of same length
-    public boolean equals(@Nullable Object object) {
+    public boolean equals(@CheckForNull Object object) {
       if (object instanceof AsList) {
         AsList that = (AsList) object;
         return this.parent.equals(that.parent);
@@ -611,7 +612,7 @@ public String toString() {
    * values as this one, in the same order.
    */
   @Override
-  public boolean equals(@Nullable Object object) {
+  public boolean equals(@CheckForNull Object object) {
     if (object == this) {
       return true;
     }
diff --git a/guava/src/com/google/common/primitives/Ints.java b/guava/src/com/google/common/primitives/Ints.java
index 7da68b484f7a..2a0b096d519b 100644
--- a/guava/src/com/google/common/primitives/Ints.java
+++ b/guava/src/com/google/common/primitives/Ints.java
@@ -33,6 +33,7 @@
 import java.util.RandomAccess;
 import java.util.Spliterator;
 import java.util.Spliterators;
+import javax.annotation.CheckForNull;
 import org.checkerframework.checker.index.qual.IndexFor;
 import org.checkerframework.checker.index.qual.IndexOrHigh;
 import org.checkerframework.checker.index.qual.IndexOrLow;
@@ -59,6 +60,7 @@
  * @since 1.0
  */
 @GwtCompatible(emulated = true)
+@ElementTypesAreNonnullByDefault
 public final class Ints extends IntsMethodsForWeb {
   private Ints() {}
 
@@ -185,6 +187,7 @@ public static boolean contains(int[] array, int target) {
    * @param array the array to search for the sequence {@code target}
    * @param target the array to search for as a sub-sequence of {@code array}
    */
+  @SuppressWarnings("substringindex:return")
   public static @LTEqLengthOf("#1") @SubstringIndexFor(value = "#1", offset="#2.length - 1") int indexOf(int[] array, int[] target) {
     checkNotNull(array, "array");
     checkNotNull(target, "target");
@@ -300,6 +303,7 @@ public static int constrainToRange(int value, int min, int max) {
    * pos is increased the same way as length, so pos points to a valid
    * range of length array.length in result.
    */
+  @SuppressWarnings("upperbound:argument") // sum of lengths
   public static int[] concat(int[]... arrays) {
     int length = 0;
     for (int[] array : arrays) {
@@ -592,6 +596,7 @@ private static class IntArrayAsList extends AbstractList<Integer>
       this(array, 0, array.length);
     }
 
+    @SuppressWarnings("index:assignment") // these three fields need to be initialized in some order, and any ordering leads to the first two issuing errors - since each field is dependent on at least one of the others
     IntArrayAsList(int @MinLen(1)[] array, @IndexFor("#1") @LessThan("#3") int start, @IndexOrHigh("#1") int end) {
       this.array = array;
       this.start = start;
@@ -620,15 +625,13 @@ public Spliterator.OfInt spliterator() {
     }
 
     @Override
-    @SuppressWarnings("signedness:argument") // passing @UnknownSignedness Integer to @Signed int
-    public boolean contains(Object target) {
+    public boolean contains(@CheckForNull Object target) {
       // Overridden to prevent a ton of boxing
       return (target instanceof Integer) && Ints.indexOf(array, (Integer) target, start, end) != -1;
     }
 
     @Override
-    @SuppressWarnings("signedness:argument") // passing @UnknownSignedness Integer to @Signed int
-    public @IndexOrLow("this") int indexOf(Object target) {
+    public @IndexOrLow("this") int indexOf(@CheckForNull Object target) {
       // Overridden to prevent a ton of boxing
       if (target instanceof Integer) {
         int i = Ints.indexOf(array, (Integer) target, start, end);
@@ -640,8 +643,7 @@ public boolean contains(Object target) {
     }
 
     @Override
-    @SuppressWarnings("signedness:argument") // passing @UnknownSignedness Integer to @Signed int
-    public @IndexOrLow("this")int lastIndexOf(Object target) {
+    public @IndexOrLow("this")int lastIndexOf(@CheckForNull Object target) {
       // Overridden to prevent a ton of boxing
       if (target instanceof Integer) {
         int i = Ints.lastIndexOf(array, (Integer) target, start, end);
@@ -662,6 +664,7 @@ public Integer set(@IndexFor("this") int index, Integer element) {
     }
 
     @Override
+    @SuppressWarnings("index:argument") // args to IntArrayAsList
     public List<Integer> subList(@IndexOrHigh("this") int fromIndex, @IndexOrHigh("this") int toIndex) {
       int size = size();
       checkPositionIndexes(fromIndex, toIndex, size);
@@ -672,7 +675,7 @@ public List<Integer> subList(@IndexOrHigh("this") int fromIndex, @IndexOrHigh("t
     }
 
     @Override
-    public boolean equals(@Nullable Object object) {
+    public boolean equals(@CheckForNull Object object) {
       if (object == this) {
         return true;
       }
@@ -736,7 +739,8 @@ int[] toIntArray() {
    * @since 11.0
    */
   @Beta
-  public static @Nullable Integer tryParse(String string) {
+  @CheckForNull
+  public static Integer tryParse(String string) {
     return tryParse(string, 10);
   }
 
@@ -761,7 +765,8 @@ int[] toIntArray() {
    * @since 19.0
    */
   @Beta
-  public static @Nullable Integer tryParse(String string, @IntRange(from=2, to=36) int radix) {
+  @CheckForNull
+  public static Integer tryParse(String string, @IntRange(from=2, to=36) int radix) {
     Long result = Longs.tryParse(string, radix);
     if (result == null || result.longValue() != result.intValue()) {
       return null;
diff --git a/guava/src/com/google/common/primitives/IntsMethodsForWeb.java b/guava/src/com/google/common/primitives/IntsMethodsForWeb.java
index cb87bd2929f8..c59c6b05862d 100644
--- a/guava/src/com/google/common/primitives/IntsMethodsForWeb.java
+++ b/guava/src/com/google/common/primitives/IntsMethodsForWeb.java
@@ -21,4 +21,5 @@
  * version.
  */
 @GwtCompatible(emulated = true)
+@ElementTypesAreNonnullByDefault
 abstract class IntsMethodsForWeb {}
diff --git a/guava/src/com/google/common/primitives/Longs.java b/guava/src/com/google/common/primitives/Longs.java
index 6cd69b0fc8cc..516077674ef7 100644
--- a/guava/src/com/google/common/primitives/Longs.java
+++ b/guava/src/com/google/common/primitives/Longs.java
@@ -32,6 +32,7 @@
 import java.util.RandomAccess;
 import java.util.Spliterator;
 import java.util.Spliterators;
+import javax.annotation.CheckForNull;
 import org.checkerframework.checker.index.qual.IndexFor;
 import org.checkerframework.checker.index.qual.IndexOrHigh;
 import org.checkerframework.checker.index.qual.IndexOrLow;
@@ -58,6 +59,7 @@
  * @since 1.0
  */
 @GwtCompatible
+@ElementTypesAreNonnullByDefault
 public final class Longs {
   private Longs() {}
 
@@ -157,6 +159,7 @@ public static boolean contains(long[] array, long target) {
    * @param array the array to search for the sequence {@code target}
    * @param target the array to search for as a sub-sequence of {@code array}
    */
+  @SuppressWarnings("substringindex:return")
   public static @LTEqLengthOf("#1") @SubstringIndexFor(value = "#1", offset="#2.length - 1") int indexOf(long[] array, long[] target) {
     checkNotNull(array, "array");
     checkNotNull(target, "target");
@@ -268,6 +271,7 @@ public static long constrainToRange(long value, long min, long max) {
    * pos is increased the same way as length, so pos points to a valid
    * range of length array.length in result.
    */
+  @SuppressWarnings("upperbound:argument") // sum of lengths
   public static long[] concat(long[]... arrays) {
     int length = 0;
     for (long[] array : arrays) {
@@ -385,7 +389,8 @@ private AsciiDigits() {}
    * @since 14.0
    */
   @Beta
-  public static @Nullable Long tryParse(String string) {
+  @CheckForNull
+  public static Long tryParse(String string) {
     return tryParse(string, 10);
   }
 
@@ -410,7 +415,8 @@ private AsciiDigits() {}
    * @since 19.0
    */
   @Beta
-  public static @Nullable Long tryParse(String string, @IntRange(from=2, to=36) int radix) {
+  @CheckForNull
+  public static Long tryParse(String string, @IntRange(from=2, to=36) int radix) {
     if (checkNotNull(string).isEmpty()) {
       return null;
     }
@@ -719,15 +725,13 @@ public Spliterator.OfLong spliterator() {
     }
 
     @Override
-    @SuppressWarnings("signedness:argument") // target is signed Long
-    public boolean contains(Object target) {
+    public boolean contains(@CheckForNull Object target) {
       // Overridden to prevent a ton of boxing
       return (target instanceof Long) && Longs.indexOf(array, (Long) target, start, end) != -1;
     }
 
     @Override
-    @SuppressWarnings("signedness:argument") // target is signed Long
-    public @IndexOrLow("this") int indexOf(Object target) {
+    public @IndexOrLow("this") int indexOf(@CheckForNull Object target) {
       // Overridden to prevent a ton of boxing
       if (target instanceof Long) {
         int i = Longs.indexOf(array, (Long) target, start, end);
@@ -739,8 +743,7 @@ public boolean contains(Object target) {
     }
 
     @Override
-    @SuppressWarnings("signedness:argument") // target is signed Long
-    public @IndexOrLow("this") int lastIndexOf(Object target) {
+    public @IndexOrLow("this") int lastIndexOf(@CheckForNull Object target) {
       // Overridden to prevent a ton of boxing
       if (target instanceof Long) {
         int i = Longs.lastIndexOf(array, (Long) target, start, end);
@@ -772,7 +775,7 @@ public List<Long> subList(@IndexOrHigh("this") int fromIndex, @IndexOrHigh("this
     }
 
     @Override
-    public boolean equals(@Nullable Object object) {
+    public boolean equals(@CheckForNull Object object) {
       if (object == this) {
         return true;
       }
diff --git a/guava/src/com/google/common/primitives/ParametricNullness.java b/guava/src/com/google/common/primitives/ParametricNullness.java
new file mode 100644
index 000000000000..4289b9b164f1
--- /dev/null
+++ b/guava/src/com/google/common/primitives/ParametricNullness.java
@@ -0,0 +1,52 @@
+/*
+ * Copyright (C) 2021 The Guava Authors
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package com.google.common.primitives;
+
+import static java.lang.annotation.ElementType.FIELD;
+import static java.lang.annotation.ElementType.METHOD;
+import static java.lang.annotation.ElementType.PARAMETER;
+import static java.lang.annotation.RetentionPolicy.RUNTIME;
+
+import com.google.common.annotations.GwtCompatible;
+import java.lang.annotation.Retention;
+import java.lang.annotation.Target;
+
+/**
+ * Marks a "top-level" type-variable usage as the closest we can get to "non-nullable when
+ * non-nullable; nullable when nullable" (like the Android <a
+ * href="https://android.googlesource.com/platform/libcore/+/master/luni/src/main/java/libcore/util/NullFromTypeParam.java">{@code
+ * NullFromTypeParam}</a>).
+ *
+ * <p>Consumers of this annotation include:
+ *
+ * <ul>
+ *   <li>Kotlin, for which it makes the type-variable usage (a) a Kotlin platform type when the type
+ *       argument is non-nullable and (b) nullable when the type argument is nullable. We use this
+ *       to "undo" {@link ElementTypesAreNonnullByDefault}.
+ *   <li><a href="https://developers.google.com/j2objc">J2ObjC</a>
+ *   <li>{@code NullPointerTester}, at least in the Android backport (where the type-use annotations
+ *       {@code NullPointerTester} would need are not available) and in case of <a
+ *       href="https://bugs.openjdk.java.net/browse/JDK-8202469">JDK-8202469</a>
+ * </ul>
+ *
+ */
+@GwtCompatible
+@Retention(RUNTIME)
+@Target({FIELD, METHOD, PARAMETER})
+@javax.annotation.meta.TypeQualifierNickname
+@javax.annotation.Nonnull(when = javax.annotation.meta.When.UNKNOWN)
+@interface ParametricNullness {}
diff --git a/guava/src/com/google/common/primitives/ParseRequest.java b/guava/src/com/google/common/primitives/ParseRequest.java
index 513c7350dcb3..7ba27d99aaaf 100644
--- a/guava/src/com/google/common/primitives/ParseRequest.java
+++ b/guava/src/com/google/common/primitives/ParseRequest.java
@@ -19,6 +19,7 @@
 
 /** A string to be parsed as a number and the radix to interpret it in. */
 @GwtCompatible
+@ElementTypesAreNonnullByDefault
 final class ParseRequest {
   final String rawValue;
   final @IntRange(from = Character.MIN_RADIX, to = Character.MAX_RADIX) int radix;
diff --git a/guava/src/com/google/common/primitives/Platform.java b/guava/src/com/google/common/primitives/Platform.java
index 7bcb0df1b658..ca31689222cd 100644
--- a/guava/src/com/google/common/primitives/Platform.java
+++ b/guava/src/com/google/common/primitives/Platform.java
@@ -18,6 +18,7 @@
 
 /** Methods factored out so that they can be emulated differently in GWT. */
 @GwtCompatible(emulated = true)
+@ElementTypesAreNonnullByDefault
 final class Platform {
   private static final java.util.logging.Logger logger =
       java.util.logging.Logger.getLogger(Platform.class.getName());
diff --git a/guava/src/com/google/common/primitives/Primitives.java b/guava/src/com/google/common/primitives/Primitives.java
index 1bdc7400f330..7ceed036555a 100644
--- a/guava/src/com/google/common/primitives/Primitives.java
+++ b/guava/src/com/google/common/primitives/Primitives.java
@@ -30,6 +30,7 @@
  * @since 1.0
  */
 @GwtIncompatible
+@ElementTypesAreNonnullByDefault
 public final class Primitives {
   private Primitives() {}
 
diff --git a/guava/src/com/google/common/primitives/Shorts.java b/guava/src/com/google/common/primitives/Shorts.java
index 4afcfb92f081..b1ee5794903b 100644
--- a/guava/src/com/google/common/primitives/Shorts.java
+++ b/guava/src/com/google/common/primitives/Shorts.java
@@ -31,6 +31,7 @@
 import java.util.Comparator;
 import java.util.List;
 import java.util.RandomAccess;
+import javax.annotation.CheckForNull;
 import org.checkerframework.checker.index.qual.IndexFor;
 import org.checkerframework.checker.index.qual.IndexOrHigh;
 import org.checkerframework.checker.index.qual.IndexOrLow;
@@ -56,6 +57,7 @@
  * @since 1.0
  */
 @GwtCompatible(emulated = true)
+@ElementTypesAreNonnullByDefault
 public final class Shorts extends ShortsMethodsForWeb {
   private Shorts() {}
 
@@ -181,7 +183,7 @@ public static boolean contains(short[] array, short target) {
    * @param array the array to search for the sequence {@code target}
    * @param target the array to search for as a sub-sequence of {@code array}
    */
-  @SuppressWarnings("substringindex:return.type.incompatible") // https://github.com/kelloggm/checker-framework/issues/206 https://github.com/kelloggm/checker-framework/issues/207 https://github.com/kelloggm/checker-framework/issues/208
+  @SuppressWarnings("substringindex:return") // https://github.com/kelloggm/checker-framework/issues/206, 207 and 208
   public static @LTEqLengthOf("#1") @SubstringIndexFor(value = "#1", offset="#2.length - 1") int indexOf(short[] array, short[] target) {
     checkNotNull(array, "array");
     checkNotNull(target, "target");
@@ -298,7 +300,7 @@ public static short constrainToRange(short value, short min, short max) {
    * pos is increased the same way as length, so pos points to a valid
    * range of length array.length in result.
    */
-  @SuppressWarnings("upperbound:argument.type.incompatible") // sum of lengths
+  @SuppressWarnings("upperbound:argument") // sum of lengths
   public static short[] concat(short[]... arrays) {
     int length = 0;
     for (short[] array : arrays) {
@@ -615,16 +617,15 @@ public Short get(@IndexFor("this") int index) {
     }
 
     @Override
-    public boolean contains(@Nullable Object target) {
+    public boolean contains(@CheckForNull Object target) {
       // Overridden to prevent a ton of boxing
       return (target instanceof Short) && Shorts.indexOf(array, (Short) target, start, end) != -1;
     }
 
 
     @Override
-    @SuppressWarnings(
-            "lowerbound") // needs https://github.com/kelloggm/checker-framework/issues/227 on static indexOf method
-    public @IndexOrLow("this") int indexOf(@Nullable Object target) {
+    @SuppressWarnings("lowerbound:return")
+    public @IndexOrLow("this") int indexOf(@CheckForNull Object target) {
       // Overridden to prevent a ton of boxing
       if (target instanceof Short) {
         int i = Shorts.indexOf(array, (Short) target, start, end);
@@ -636,9 +637,8 @@ public boolean contains(@Nullable Object target) {
     }
 
     @Override
-    @SuppressWarnings(
-            "lowerbound:return.type.incompatible") // needs https://github.com/kelloggm/checker-framework/issues/227 on static lastIndexOf method
-    public @IndexOrLow("this") int lastIndexOf(@Nullable Object target) {
+    @SuppressWarnings("lowerbound:return")
+    public @IndexOrLow("this") int lastIndexOf(@CheckForNull Object target) {
       // Overridden to prevent a ton of boxing
       if (target instanceof Short) {
         int i = Shorts.lastIndexOf(array, (Short) target, start, end);
@@ -670,7 +670,7 @@ public List<Short> subList(@IndexOrHigh("this") int fromIndex, @IndexOrHigh("thi
     }
 
     @Override
-    public boolean equals(@Nullable Object object) {
+    public boolean equals(@CheckForNull Object object) {
       if (object == this) {
         return true;
       }
diff --git a/guava/src/com/google/common/primitives/ShortsMethodsForWeb.java b/guava/src/com/google/common/primitives/ShortsMethodsForWeb.java
index c36276838cc6..bb0ff103ce2f 100644
--- a/guava/src/com/google/common/primitives/ShortsMethodsForWeb.java
+++ b/guava/src/com/google/common/primitives/ShortsMethodsForWeb.java
@@ -21,4 +21,5 @@
  * version.
  */
 @GwtCompatible(emulated = true)
+@ElementTypesAreNonnullByDefault
 abstract class ShortsMethodsForWeb {}
diff --git a/guava/src/com/google/common/primitives/SignedBytes.java b/guava/src/com/google/common/primitives/SignedBytes.java
index 85c37780f7aa..d24217444e24 100644
--- a/guava/src/com/google/common/primitives/SignedBytes.java
+++ b/guava/src/com/google/common/primitives/SignedBytes.java
@@ -39,6 +39,7 @@
 // TODO(kevinb): how to prevent warning on UnsignedBytes when building GWT
 // javadoc?
 @GwtCompatible
+@ElementTypesAreNonnullByDefault
 public final class SignedBytes {
   private SignedBytes() {}
 
diff --git a/guava/src/com/google/common/primitives/UnsignedBytes.java b/guava/src/com/google/common/primitives/UnsignedBytes.java
index daa35be2a67c..b4048cd74a99 100644
--- a/guava/src/com/google/common/primitives/UnsignedBytes.java
+++ b/guava/src/com/google/common/primitives/UnsignedBytes.java
@@ -17,6 +17,7 @@
 import static com.google.common.base.Preconditions.checkArgument;
 import static com.google.common.base.Preconditions.checkNotNull;
 import static com.google.common.base.Preconditions.checkPositionIndexes;
+import static java.util.Objects.requireNonNull;
 
 import com.google.common.annotations.Beta;
 import com.google.common.annotations.GwtIncompatible;
@@ -52,6 +53,7 @@
  * @since 1.0
  */
 @GwtIncompatible
+@ElementTypesAreNonnullByDefault
 public final class UnsignedBytes {
   private UnsignedBytes() {}
 
@@ -374,7 +376,7 @@ public sun.misc.Unsafe run() throws Exception {
 
       @Override
       public int compare(@Unsigned byte[] left, @Unsigned byte[] right) {
-        final int stride = 8;
+        int stride = 8;
         int minLength = Math.min(left.length, right.length);
         int strideLimit = minLength & ~(stride - 1);
         int i;
@@ -453,9 +455,12 @@ public String toString() {
       try {
         Class<?> theClass = Class.forName(UNSAFE_COMPARATOR_NAME);
 
+        // requireNonNull is safe because the class is an enum.
+        Object[] constants = requireNonNull(theClass.getEnumConstants());
+
         // yes, UnsafeComparator does implement Comparator<byte[]>
         @SuppressWarnings("unchecked")
-        Comparator<@Unsigned byte[]> comparator = (Comparator<@Unsigned byte[]>) theClass.getEnumConstants()[0];
+        Comparator<@Unsigned byte[]> comparator = (Comparator<@Unsigned byte[]>) constants[0];
         return comparator;
       } catch (Throwable t) { // ensure we really catch *everything*
         return lexicographicalComparatorJavaImpl();
diff --git a/guava/src/com/google/common/primitives/UnsignedInteger.java b/guava/src/com/google/common/primitives/UnsignedInteger.java
index 4cd3068c0b95..518cc02e6f66 100644
--- a/guava/src/com/google/common/primitives/UnsignedInteger.java
+++ b/guava/src/com/google/common/primitives/UnsignedInteger.java
@@ -23,6 +23,7 @@
 import com.google.common.annotations.GwtCompatible;
 import com.google.common.annotations.GwtIncompatible;
 import java.math.BigInteger;
+import javax.annotation.CheckForNull;
 import org.checkerframework.checker.index.qual.NonNegative;
 import org.checkerframework.checker.index.qual.Positive;
 import org.checkerframework.checker.nullness.qual.Nullable;
@@ -43,6 +44,7 @@
  * @since 11.0
  */
 @GwtCompatible(emulated = true)
+@ElementTypesAreNonnullByDefault
 public final class UnsignedInteger extends Number implements Comparable<UnsignedInteger> {
   public static final UnsignedInteger ZERO = fromIntBits(0);
   public static final UnsignedInteger ONE = fromIntBits(1);
@@ -188,7 +190,7 @@ public UnsignedInteger mod(UnsignedInteger val) {
   /** Returns the value of this {@code UnsignedInteger} as a {@code long}. */
   @Override
   @SuppressWarnings("cast.unsafe")
-  public @NonNegative @PolyValue long longValue(@PolyValue UnsignedInteger this) {
+  public @PolyValue long longValue(@PolyValue UnsignedInteger this) {
     return (@PolyValue long) toLong(value);
   }
 
@@ -233,7 +235,7 @@ public int hashCode() {
   }
 
   @Override
-  public boolean equals(@Nullable Object obj) {
+  public boolean equals(@CheckForNull Object obj) {
     if (obj instanceof UnsignedInteger) {
       UnsignedInteger other = (UnsignedInteger) obj;
       return value == other.value;
diff --git a/guava/src/com/google/common/primitives/UnsignedInts.java b/guava/src/com/google/common/primitives/UnsignedInts.java
index fadc6a69e78e..2cde48586ddf 100644
--- a/guava/src/com/google/common/primitives/UnsignedInts.java
+++ b/guava/src/com/google/common/primitives/UnsignedInts.java
@@ -56,6 +56,7 @@
  */
 @Beta
 @GwtCompatible
+@ElementTypesAreNonnullByDefault
 public final class UnsignedInts {
   static final long INT_MASK = 0xffffffffL;
 
diff --git a/guava/src/com/google/common/primitives/UnsignedLong.java b/guava/src/com/google/common/primitives/UnsignedLong.java
index 07d8280fb3cd..e1643ca76905 100644
--- a/guava/src/com/google/common/primitives/UnsignedLong.java
+++ b/guava/src/com/google/common/primitives/UnsignedLong.java
@@ -21,6 +21,7 @@
 import com.google.errorprone.annotations.CanIgnoreReturnValue;
 import java.io.Serializable;
 import java.math.BigInteger;
+import javax.annotation.CheckForNull;
 import org.checkerframework.checker.index.qual.NonNegative;
 import org.checkerframework.checker.nullness.qual.Nullable;
 import org.checkerframework.checker.signedness.qual.Signed;
@@ -43,6 +44,7 @@
  * @since 11.0
  */
 @GwtCompatible(serializable = true)
+@ElementTypesAreNonnullByDefault
 public final class UnsignedLong extends Number implements Comparable<UnsignedLong>, Serializable {
 
   private static final long UNSIGNED_MASK = 0x7fffffffffffffffL;
@@ -201,17 +203,17 @@ public UnsignedLong mod(UnsignedLong val) {
    * Returns the value of this {@code UnsignedLong} as a {@code float}, analogous to a widening
    * primitive conversion from {@code long} to {@code float}, and correctly rounded.
    */
-  @Override
   @SuppressWarnings({
     "signedness:comparison", // unsigned compare
     "value:return" // forDigit
   })
   public @PolyValue float floatValue(@PolyValue UnsignedLong this) {
-    float fValue = (float) (value & UNSIGNED_MASK);
-    if (value < 0) {
-      fValue += 0x1.0p63f;
+    if (value >= 0) {
+      return (float) value;
     }
-    return fValue;
+    // The top bit is set, which means that the float value is going to come from the top 24 bits.
+    // So we can ignore the bottom 8, except for rounding. See doubleValue() for more.
+    return (float) ((value >>> 1) | (value & 1)) * 2f;
   }
 
   /**
@@ -224,11 +226,15 @@ public UnsignedLong mod(UnsignedLong val) {
     "value:return" // forDigit
   })
   public @PolyValue double doubleValue(@PolyValue UnsignedLong this) {
-    double dValue = (double) (value & UNSIGNED_MASK);
-    if (value < 0) {
-      dValue += 0x1.0p63;
+    if (value >= 0) {
+      return (double) value;
     }
-    return dValue;
+    // The top bit is set, which means that the double value is going to come from the top 53 bits.
+    // So we can ignore the bottom 11, except for rounding. We can unsigned-shift right 1, aka
+    // unsigned-divide by 2, and convert that. Then we'll get exactly half of the desired double
+    // value. But in the specific case where the bottom two bits of the original number are 01, we
+    // want to replace that with 1 in the shifted value for correct rounding.
+    return (double) ((value >>> 1) | (value & 1)) * 2.0;
   }
 
   /** Returns the value of this {@code UnsignedLong} as a {@link BigInteger}. */
@@ -254,7 +260,7 @@ public int hashCode() {
   }
 
   @Override
-  public boolean equals(@Nullable Object obj) {
+  public boolean equals(@CheckForNull Object obj) {
     if (obj instanceof UnsignedLong) {
       UnsignedLong other = (UnsignedLong) obj;
       return value == other.value;
diff --git a/guava/src/com/google/common/primitives/UnsignedLongs.java b/guava/src/com/google/common/primitives/UnsignedLongs.java
index 1542a4b8eade..09fcf1559d21 100644
--- a/guava/src/com/google/common/primitives/UnsignedLongs.java
+++ b/guava/src/com/google/common/primitives/UnsignedLongs.java
@@ -58,6 +58,7 @@
 @AnnotatedFor({"signedness"})
 @Beta
 @GwtCompatible
+@ElementTypesAreNonnullByDefault
 public final class UnsignedLongs {
   private UnsignedLongs() {}
 
diff --git a/guava/src/com/google/common/reflect/AbstractInvocationHandler.java b/guava/src/com/google/common/reflect/AbstractInvocationHandler.java
index 45aea776f9cc..ff921959db39 100644
--- a/guava/src/com/google/common/reflect/AbstractInvocationHandler.java
+++ b/guava/src/com/google/common/reflect/AbstractInvocationHandler.java
@@ -14,11 +14,11 @@
 
 package com.google.common.reflect;
 
-import com.google.common.annotations.Beta;
 import java.lang.reflect.InvocationHandler;
 import java.lang.reflect.Method;
 import java.lang.reflect.Proxy;
 import java.util.Arrays;
+import javax.annotation.CheckForNull;
 import org.checkerframework.checker.nullness.qual.Nullable;
 
 /**
@@ -38,7 +38,7 @@
  * @author Ben Yu
  * @since 12.0
  */
-@Beta
+@ElementTypesAreNonnullByDefault
 public abstract class AbstractInvocationHandler implements InvocationHandler {
 
   private static final Object[] NO_ARGS = {};
@@ -59,7 +59,8 @@ public abstract class AbstractInvocationHandler implements InvocationHandler {
    * </ul>
    */
   @Override
-  public final Object invoke(Object proxy, Method method, Object @Nullable [] args)
+  @CheckForNull
+  public final Object invoke(Object proxy, Method method, @CheckForNull @Nullable Object[] args)
       throws Throwable {
     if (args == null) {
       args = NO_ARGS;
@@ -94,7 +95,8 @@ public final Object invoke(Object proxy, Method method, Object @Nullable [] args
    * <p>Unlike {@link #invoke}, {@code args} will never be null. When the method has no parameter,
    * an empty array is passed in.
    */
-  protected abstract Object handleInvocation(Object proxy, Method method, Object[] args)
+  @CheckForNull
+  protected abstract Object handleInvocation(Object proxy, Method method, @Nullable Object[] args)
       throws Throwable;
 
   /**
@@ -109,7 +111,7 @@ protected abstract Object handleInvocation(Object proxy, Method method, Object[]
    * <p>Subclasses can override this method to provide custom equality.
    */
   @Override
-  public boolean equals(Object obj) {
+  public boolean equals(@CheckForNull Object obj) {
     return super.equals(obj);
   }
 
diff --git a/guava/src/com/google/common/reflect/ClassPath.java b/guava/src/com/google/common/reflect/ClassPath.java
index 9f052d49fbbf..627532f8408e 100644
--- a/guava/src/com/google/common/reflect/ClassPath.java
+++ b/guava/src/com/google/common/reflect/ClassPath.java
@@ -20,10 +20,8 @@
 import static com.google.common.base.StandardSystemProperty.PATH_SEPARATOR;
 import static java.util.logging.Level.WARNING;
 
-import com.google.common.annotations.Beta;
 import com.google.common.annotations.VisibleForTesting;
 import com.google.common.base.CharMatcher;
-import com.google.common.base.Predicate;
 import com.google.common.base.Splitter;
 import com.google.common.collect.FluentIterable;
 import com.google.common.collect.ImmutableList;
@@ -51,19 +49,40 @@
 import java.util.jar.JarFile;
 import java.util.jar.Manifest;
 import java.util.logging.Logger;
-import org.checkerframework.checker.nullness.qual.Nullable;
+import javax.annotation.CheckForNull;
 
 /**
  * Scans the source of a {@link ClassLoader} and finds all loadable classes and resources.
  *
- * <p><b>Warning:</b> Current limitations:
+ * <h2>Prefer <a href="https://github.com/classgraph/classgraph/wiki">ClassGraph</a> over {@code
+ * ClassPath}</h2>
+ *
+ * <p>We recommend using <a href="https://github.com/classgraph/classgraph/wiki">ClassGraph</a>
+ * instead of {@code ClassPath}. ClassGraph improves upon {@code ClassPath} in several ways,
+ * including addressing many of its limitations. Limitations of {@code ClassPath} include:
  *
  * <ul>
- *   <li>Looks only for files and JARs in URLs available from {@link URLClassLoader} instances or
- *       the {@linkplain ClassLoader#getSystemClassLoader() system class loader}.
- *   <li>Only understands {@code file:} URLs.
+ *   <li>It looks only for files and JARs in URLs available from {@link URLClassLoader} instances or
+ *       the {@linkplain ClassLoader#getSystemClassLoader() system class loader}. This means it does
+ *       not look for classes in the <i>module path</i>.
+ *   <li>It understands only {@code file:} URLs. This means that it does not understand <a
+ *       href="https://openjdk.java.net/jeps/220">{@code jrt:/} URLs</a>, among <a
+ *       href="https://github.com/classgraph/classgraph/wiki/Classpath-specification-mechanisms">others</a>.
+ *   <li>It does not know how to look for classes when running under an Android VM. (ClassGraph does
+ *       not support this directly, either, but ClassGraph documents how to <a
+ *       href="https://github.com/classgraph/classgraph/wiki/Build-Time-Scanning">perform build-time
+ *       classpath scanning and make the results available to an Android app</a>.)
+ *   <li>Like all of Guava, it is not tested under Windows. We have gotten <a
+ *       href="https://github.com/google/guava/issues/2130">a report of a specific bug under
+ *       Windows</a>.
+ *   <li>It <a href="https://github.com/google/guava/issues/2712">returns only one resource for a
+ *       given path</a>, even if resources with that path appear in multiple jars or directories.
+ *   <li>It assumes that <a href="https://github.com/google/guava/issues/3349">any class with a
+ *       {@code $} in its name is a nested class</a>.
  * </ul>
  *
+ * <h2>{@code ClassPath} and symlinks</h2>
+ *
  * <p>In the case of directory classloaders, symlinks are supported but cycles are not traversed.
  * This guarantees discovery of each <em>unique</em> loadable resource. However, not all possible
  * aliases for resources on cyclic paths will be listed.
@@ -71,7 +90,7 @@
  * @author Ben Yu
  * @since 14.0
  */
-@Beta
+@ElementTypesAreNonnullByDefault
 public final class ClassPath {
   private static final Logger logger = Logger.getLogger(ClassPath.class.getName());
 
@@ -145,13 +164,7 @@ public ImmutableSet<ClassInfo> getAllClasses() {
   public ImmutableSet<ClassInfo> getTopLevelClasses() {
     return FluentIterable.from(resources)
         .filter(ClassInfo.class)
-        .filter(
-            new Predicate<ClassInfo>() {
-              @Override
-              public boolean apply(ClassInfo info) {
-                return info.isTopLevel();
-              }
-            })
+        .filter(ClassInfo::isTopLevel)
         .toSet();
   }
 
@@ -189,7 +202,6 @@ public ImmutableSet<ClassInfo> getTopLevelClassesRecursive(String packageName) {
    *
    * @since 14.0
    */
-  @Beta
   public static class ResourceInfo {
     private final File file;
     private final String resourceName;
@@ -265,7 +277,7 @@ public int hashCode() {
     }
 
     @Override
-    public boolean equals(Object obj) {
+    public boolean equals(@CheckForNull Object obj) {
       if (obj instanceof ResourceInfo) {
         ResourceInfo that = (ResourceInfo) obj;
         return resourceName.equals(that.resourceName) && loader == that.loader;
@@ -285,7 +297,6 @@ public String toString() {
    *
    * @since 14.0
    */
-  @Beta
   public static final class ClassInfo extends ResourceInfo {
     private final String className;
 
@@ -297,8 +308,13 @@ public static final class ClassInfo extends ResourceInfo {
     /**
      * Returns the package name of the class, without attempting to load the class.
      *
-     * <p>Behaves identically to {@link Package#getName()} but does not require the class (or
-     * package) to be loaded.
+     * <p>Behaves similarly to {@code class.getPackage().}{@link Package#getName() getName()} but
+     * does not require the class (or package) to be loaded.
+     *
+     * <p>But note that this method may behave differently for a class in the default package: For
+     * such classes, this method always returns an empty string. But under some version of Java,
+     * {@code class.getPackage().getName()} produces a {@code NullPointerException} because {@code
+     * class.getPackage()} returns {@code null}.
      */
     public String getPackageName() {
       return Reflection.getPackageName(className);
@@ -307,8 +323,11 @@ public String getPackageName() {
     /**
      * Returns the simple name of the underlying class as given in the source code.
      *
-     * <p>Behaves identically to {@link Class#getSimpleName()} but does not require the class to be
+     * <p>Behaves similarly to {@link Class#getSimpleName()} but does not require the class to be
      * loaded.
+     *
+     * <p>But note that this class uses heuristics to identify the simple name. See a related
+     * discussion in <a href="https://github.com/google/guava/issues/3349">issue 3349</a>.
      */
     public String getSimpleName() {
       int lastDollarSign = className.lastIndexOf('$');
@@ -531,7 +550,7 @@ private void scanDirectory(
     }
 
     @Override
-    public boolean equals(Object obj) {
+    public boolean equals(@CheckForNull Object obj) {
       if (obj instanceof LocationInfo) {
         LocationInfo that = (LocationInfo) obj;
         return home.equals(that.home) && classloader.equals(that.classloader);
@@ -558,7 +577,8 @@ public String toString() {
    * an empty set will be returned.
    */
   @VisibleForTesting
-  static ImmutableSet<File> getClassPathFromManifest(File jarFile, @Nullable Manifest manifest) {
+  static ImmutableSet<File> getClassPathFromManifest(
+      File jarFile, @CheckForNull Manifest manifest) {
     if (manifest == null) {
       return ImmutableSet.of();
     }
@@ -617,6 +637,7 @@ private static ImmutableList<URL> getClassLoaderUrls(ClassLoader classloader) {
    * System#getProperty system property}.
    */
   @VisibleForTesting // TODO(b/65488446): Make this a public API.
+  @SuppressWarnings("value:argument") // arg to .on should be @MinLen(1)
   static ImmutableList<URL> parseJavaClassPath() {
     ImmutableList.Builder<URL> urls = ImmutableList.builder();
     for (String entry : Splitter.on(PATH_SEPARATOR.value()).split(JAVA_CLASS_PATH.value())) {
diff --git a/guava/src/com/google/common/reflect/Element.java b/guava/src/com/google/common/reflect/Element.java
deleted file mode 100644
index c63c09aaff31..000000000000
--- a/guava/src/com/google/common/reflect/Element.java
+++ /dev/null
@@ -1,178 +0,0 @@
-/*
- * Copyright (C) 2012 The Guava Authors
- *
- * Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file except
- * in compliance with the License. You may obtain a copy of the License at
- *
- * http://www.apache.org/licenses/LICENSE-2.0
- *
- * Unless required by applicable law or agreed to in writing, software distributed under the License
- * is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express
- * or implied. See the License for the specific language governing permissions and limitations under
- * the License.
- */
-
-package com.google.common.reflect;
-
-import static com.google.common.base.Preconditions.checkNotNull;
-
-import java.lang.annotation.Annotation;
-import java.lang.reflect.AccessibleObject;
-import java.lang.reflect.Constructor;
-import java.lang.reflect.Field;
-import java.lang.reflect.Member;
-import java.lang.reflect.Method;
-import java.lang.reflect.Modifier;
-import org.checkerframework.checker.nullness.qual.Nullable;
-
-/**
- * Represents either a {@link Field}, a {@link Method} or a {@link Constructor}. Provides
- * convenience methods such as {@link #isPublic} and {@link #isPackagePrivate}.
- *
- * @author Ben Yu
- */
-class Element extends AccessibleObject implements Member {
-
-  private final AccessibleObject accessibleObject;
-  private final Member member;
-
-  <M extends AccessibleObject & Member> Element(M member) {
-    checkNotNull(member);
-    this.accessibleObject = member;
-    this.member = member;
-  }
-
-  public TypeToken<?> getOwnerType() {
-    return TypeToken.of(getDeclaringClass());
-  }
-
-  @Override
-  public final boolean isAnnotationPresent(Class<? extends Annotation> annotationClass) {
-    return accessibleObject.isAnnotationPresent(annotationClass);
-  }
-
-  @Override
-  public final <A extends Annotation> A getAnnotation(Class<A> annotationClass) {
-    return accessibleObject.getAnnotation(annotationClass);
-  }
-
-  @Override
-  public final Annotation[] getAnnotations() {
-    return accessibleObject.getAnnotations();
-  }
-
-  @Override
-  public final Annotation[] getDeclaredAnnotations() {
-    return accessibleObject.getDeclaredAnnotations();
-  }
-
-  @Override
-  public final void setAccessible(boolean flag) throws SecurityException {
-    accessibleObject.setAccessible(flag);
-  }
-
-  @Override
-  public final boolean isAccessible() {
-    return accessibleObject.isAccessible();
-  }
-
-  @Override
-  public Class<?> getDeclaringClass() {
-    return member.getDeclaringClass();
-  }
-
-  @Override
-  public final String getName() {
-    return member.getName();
-  }
-
-  @Override
-  public final int getModifiers() {
-    return member.getModifiers();
-  }
-
-  @Override
-  public final boolean isSynthetic() {
-    return member.isSynthetic();
-  }
-
-  /** Returns true if the element is public. */
-  public final boolean isPublic() {
-    return Modifier.isPublic(getModifiers());
-  }
-
-  /** Returns true if the element is protected. */
-  public final boolean isProtected() {
-    return Modifier.isProtected(getModifiers());
-  }
-
-  /** Returns true if the element is package-private. */
-  public final boolean isPackagePrivate() {
-    return !isPrivate() && !isPublic() && !isProtected();
-  }
-
-  /** Returns true if the element is private. */
-  public final boolean isPrivate() {
-    return Modifier.isPrivate(getModifiers());
-  }
-
-  /** Returns true if the element is static. */
-  public final boolean isStatic() {
-    return Modifier.isStatic(getModifiers());
-  }
-
-  /**
-   * Returns {@code true} if this method is final, per {@code Modifier.isFinal(getModifiers())}.
-   *
-   * <p>Note that a method may still be effectively "final", or non-overridable when it has no
-   * {@code final} keyword. For example, it could be private, or it could be declared by a final
-   * class. To tell whether a method is overridable, use {@link Invokable#isOverridable}.
-   */
-  public final boolean isFinal() {
-    return Modifier.isFinal(getModifiers());
-  }
-
-  /** Returns true if the method is abstract. */
-  public final boolean isAbstract() {
-    return Modifier.isAbstract(getModifiers());
-  }
-
-  /** Returns true if the element is native. */
-  public final boolean isNative() {
-    return Modifier.isNative(getModifiers());
-  }
-
-  /** Returns true if the method is synchronized. */
-  public final boolean isSynchronized() {
-    return Modifier.isSynchronized(getModifiers());
-  }
-
-  /** Returns true if the field is volatile. */
-  final boolean isVolatile() {
-    return Modifier.isVolatile(getModifiers());
-  }
-
-  /** Returns true if the field is transient. */
-  final boolean isTransient() {
-    return Modifier.isTransient(getModifiers());
-  }
-
-  @Override
-  public boolean equals(@Nullable Object obj) {
-    if (obj instanceof Element) {
-      Element that = (Element) obj;
-      return getOwnerType().equals(that.getOwnerType()) && member.equals(that.member);
-    }
-    return false;
-  }
-
-  @Override
-  public int hashCode() {
-    return member.hashCode();
-  }
-
-  @Override
-  public String toString() {
-    return member.toString();
-  }
-}
diff --git a/guava/src/com/google/common/reflect/ElementTypesAreNonnullByDefault.java b/guava/src/com/google/common/reflect/ElementTypesAreNonnullByDefault.java
new file mode 100644
index 000000000000..0e8ef3cb7bcb
--- /dev/null
+++ b/guava/src/com/google/common/reflect/ElementTypesAreNonnullByDefault.java
@@ -0,0 +1,41 @@
+/*
+ * Copyright (C) 2021 The Guava Authors
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package com.google.common.reflect;
+
+import static java.lang.annotation.ElementType.FIELD;
+import static java.lang.annotation.ElementType.METHOD;
+import static java.lang.annotation.ElementType.PARAMETER;
+import static java.lang.annotation.ElementType.TYPE;
+import static java.lang.annotation.RetentionPolicy.RUNTIME;
+
+import com.google.common.annotations.GwtCompatible;
+import java.lang.annotation.Retention;
+import java.lang.annotation.Target;
+import javax.annotation.Nonnull;
+import javax.annotation.meta.TypeQualifierDefault;
+
+/**
+ * Marks all "top-level" types as non-null in a way that is recognized by Kotlin. Note that this
+ * unfortunately includes type-variable usages, so we also provide {@link ParametricNullness} to
+ * "undo" it as best we can.
+ */
+@GwtCompatible
+@Retention(RUNTIME)
+@Target(TYPE)
+@TypeQualifierDefault({FIELD, METHOD, PARAMETER})
+@Nonnull
+@interface ElementTypesAreNonnullByDefault {}
diff --git a/guava/src/com/google/common/reflect/ImmutableTypeToInstanceMap.java b/guava/src/com/google/common/reflect/ImmutableTypeToInstanceMap.java
index 7fad5ded3bdf..6273704a1072 100644
--- a/guava/src/com/google/common/reflect/ImmutableTypeToInstanceMap.java
+++ b/guava/src/com/google/common/reflect/ImmutableTypeToInstanceMap.java
@@ -14,12 +14,12 @@
 
 package com.google.common.reflect;
 
-import com.google.common.annotations.Beta;
 import com.google.common.collect.ForwardingMap;
 import com.google.common.collect.ImmutableMap;
 import com.google.errorprone.annotations.CanIgnoreReturnValue;
 import com.google.errorprone.annotations.DoNotCall;
 import java.util.Map;
+import javax.annotation.CheckForNull;
 
 /**
  * A type-to-instance map backed by an {@link ImmutableMap}. See also {@link
@@ -28,18 +28,18 @@
  * @author Ben Yu
  * @since 13.0
  */
-@Beta
+@ElementTypesAreNonnullByDefault
 public final class ImmutableTypeToInstanceMap<B> extends ForwardingMap<TypeToken<? extends B>, B>
     implements TypeToInstanceMap<B> {
 
   /** Returns an empty type to instance map. */
   public static <B> ImmutableTypeToInstanceMap<B> of() {
-    return new ImmutableTypeToInstanceMap<B>(ImmutableMap.<TypeToken<? extends B>, B>of());
+    return new ImmutableTypeToInstanceMap<>(ImmutableMap.<TypeToken<? extends B>, B>of());
   }
 
   /** Returns a new builder. */
   public static <B> Builder<B> builder() {
-    return new Builder<B>();
+    return new Builder<>();
   }
 
   /**
@@ -58,7 +58,6 @@ public static <B> Builder<B> builder() {
    *
    * @since 13.0
    */
-  @Beta
   public static final class Builder<B> {
     private final ImmutableMap.Builder<TypeToken<? extends B>, B> mapBuilder =
         ImmutableMap.builder();
@@ -91,7 +90,7 @@ public <T extends B> Builder<B> put(TypeToken<T> key, T value) {
      * @throws IllegalArgumentException if duplicate keys were added
      */
     public ImmutableTypeToInstanceMap<B> build() {
-      return new ImmutableTypeToInstanceMap<B>(mapBuilder.build());
+      return new ImmutableTypeToInstanceMap<>(mapBuilder.buildOrThrow());
     }
   }
 
@@ -102,11 +101,13 @@ private ImmutableTypeToInstanceMap(ImmutableMap<TypeToken<? extends B>, B> deleg
   }
 
   @Override
+  @CheckForNull
   public <T extends B> T getInstance(TypeToken<T> type) {
     return trustedGet(type.rejectTypeVariables());
   }
 
   @Override
+  @CheckForNull
   public <T extends B> T getInstance(Class<T> type) {
     return trustedGet(TypeToken.of(type));
   }
@@ -121,6 +122,7 @@ public <T extends B> T getInstance(Class<T> type) {
   @Deprecated
   @Override
   @DoNotCall("Always throws UnsupportedOperationException")
+  @CheckForNull
   public <T extends B> T putInstance(TypeToken<T> type, T value) {
     throw new UnsupportedOperationException();
   }
@@ -135,6 +137,7 @@ public <T extends B> T putInstance(TypeToken<T> type, T value) {
   @Deprecated
   @Override
   @DoNotCall("Always throws UnsupportedOperationException")
+  @CheckForNull
   public <T extends B> T putInstance(Class<T> type, T value) {
     throw new UnsupportedOperationException();
   }
@@ -149,6 +152,7 @@ public <T extends B> T putInstance(Class<T> type, T value) {
   @Deprecated
   @Override
   @DoNotCall("Always throws UnsupportedOperationException")
+  @CheckForNull
   public B put(TypeToken<? extends B> key, B value) {
     throw new UnsupportedOperationException();
   }
@@ -172,6 +176,7 @@ protected Map<TypeToken<? extends B>, B> delegate() {
   }
 
   @SuppressWarnings("unchecked") // value could not get in if not a T
+  @CheckForNull
   private <T extends B> T trustedGet(TypeToken<T> type) {
     return (T) delegate.get(type);
   }
diff --git a/guava/src/com/google/common/reflect/Invokable.java b/guava/src/com/google/common/reflect/Invokable.java
index e0a9ab509b2d..e6d3b6c53f7f 100644
--- a/guava/src/com/google/common/reflect/Invokable.java
+++ b/guava/src/com/google/common/reflect/Invokable.java
@@ -21,9 +21,9 @@
 import com.google.errorprone.annotations.CanIgnoreReturnValue;
 import java.lang.annotation.Annotation;
 import java.lang.reflect.AccessibleObject;
+import java.lang.reflect.AnnotatedElement;
 import java.lang.reflect.AnnotatedType;
 import java.lang.reflect.Constructor;
-import java.lang.reflect.GenericDeclaration;
 import java.lang.reflect.InvocationTargetException;
 import java.lang.reflect.Member;
 import java.lang.reflect.Method;
@@ -31,6 +31,7 @@
 import java.lang.reflect.Type;
 import java.lang.reflect.TypeVariable;
 import java.util.Arrays;
+import javax.annotation.CheckForNull;
 import org.checkerframework.checker.nullness.qual.Nullable;
 
 /**
@@ -49,17 +50,29 @@
  * assertEquals(new TypeToken<List<String>>() {}, invokable.getOwnerType());
  * }</pre>
  *
+ * <p><b>Note:</b> earlier versions of this class inherited from {@link
+ * java.lang.reflect.AccessibleObject AccessibleObject} and {@link
+ * java.lang.reflect.GenericDeclaration GenericDeclaration}. Since version 31.0 that is no longer
+ * the case. However, most methods from those types are present with the same signature in this
+ * class.
+ *
  * @param <T> the type that owns this method or constructor.
  * @param <R> the return type of (or supertype thereof) the method or the declaring type of the
  *     constructor.
  * @author Ben Yu
- * @since 14.0
+ * @since 14.0 (no longer implements {@link AccessibleObject} or {@code GenericDeclaration} since
+ *     31.0)
  */
 @Beta
-public abstract class Invokable<T, R> extends Element implements GenericDeclaration {
+@ElementTypesAreNonnullByDefault
+public abstract class Invokable<T, R> implements AnnotatedElement, Member {
+  private final AccessibleObject accessibleObject;
+  private final Member member;
 
   <M extends AccessibleObject & Member> Invokable(M member) {
-    super(member);
+    checkNotNull(member);
+    this.accessibleObject = member;
+    this.member = member;
   }
 
   /** Returns {@link Invokable} of {@code method}. */
@@ -72,6 +85,151 @@ public static <T> Invokable<T, T> from(Constructor<T> constructor) {
     return new ConstructorInvokable<T>(constructor);
   }
 
+  @Override
+  public final boolean isAnnotationPresent(Class<? extends Annotation> annotationClass) {
+    return accessibleObject.isAnnotationPresent(annotationClass);
+  }
+
+  @Override
+  @CheckForNull
+  public final <A extends Annotation> A getAnnotation(Class<A> annotationClass) {
+    return accessibleObject.getAnnotation(annotationClass);
+  }
+
+  @Override
+  public final Annotation[] getAnnotations() {
+    return accessibleObject.getAnnotations();
+  }
+
+  @Override
+  public final Annotation[] getDeclaredAnnotations() {
+    return accessibleObject.getDeclaredAnnotations();
+  }
+
+  // We ought to be able to implement GenericDeclaration instead its parent AnnotatedElement.
+  // That would give us this method declaration. But for some reason, implementing
+  // GenericDeclaration leads to weird errors in Android tests:
+  // IncompatibleClassChangeError: interface not implemented
+  /** See {@link java.lang.reflect.GenericDeclaration#getTypeParameters()}. */
+  public abstract TypeVariable<?>[] getTypeParameters();
+
+  /** See {@link java.lang.reflect.AccessibleObject#setAccessible(boolean)}. */
+  public final void setAccessible(boolean flag) {
+    accessibleObject.setAccessible(flag);
+  }
+
+  /** See {@link java.lang.reflect.AccessibleObject#trySetAccessible()}. */
+  public final boolean trySetAccessible() {
+    // We can't call accessibleObject.trySetAccessible since that was added in Java 9 and this code
+    // should work on Java 8. So we emulate it this way.
+    try {
+      accessibleObject.setAccessible(true);
+      return true;
+    } catch (RuntimeException e) {
+      return false;
+    }
+  }
+
+  /** See {@link java.lang.reflect.AccessibleObject#isAccessible()}. */
+  public final boolean isAccessible() {
+    return accessibleObject.isAccessible();
+  }
+
+  @Override
+  public final String getName() {
+    return member.getName();
+  }
+
+  @Override
+  public final int getModifiers() {
+    return member.getModifiers();
+  }
+
+  @Override
+  public final boolean isSynthetic() {
+    return member.isSynthetic();
+  }
+
+  /** Returns true if the element is public. */
+  public final boolean isPublic() {
+    return Modifier.isPublic(getModifiers());
+  }
+
+  /** Returns true if the element is protected. */
+  public final boolean isProtected() {
+    return Modifier.isProtected(getModifiers());
+  }
+
+  /** Returns true if the element is package-private. */
+  public final boolean isPackagePrivate() {
+    return !isPrivate() && !isPublic() && !isProtected();
+  }
+
+  /** Returns true if the element is private. */
+  public final boolean isPrivate() {
+    return Modifier.isPrivate(getModifiers());
+  }
+
+  /** Returns true if the element is static. */
+  public final boolean isStatic() {
+    return Modifier.isStatic(getModifiers());
+  }
+
+  /**
+   * Returns {@code true} if this method is final, per {@code Modifier.isFinal(getModifiers())}.
+   *
+   * <p>Note that a method may still be effectively "final", or non-overridable when it has no
+   * {@code final} keyword. For example, it could be private, or it could be declared by a final
+   * class. To tell whether a method is overridable, use {@link Invokable#isOverridable}.
+   */
+  public final boolean isFinal() {
+    return Modifier.isFinal(getModifiers());
+  }
+
+  /** Returns true if the method is abstract. */
+  public final boolean isAbstract() {
+    return Modifier.isAbstract(getModifiers());
+  }
+
+  /** Returns true if the element is native. */
+  public final boolean isNative() {
+    return Modifier.isNative(getModifiers());
+  }
+
+  /** Returns true if the method is synchronized. */
+  public final boolean isSynchronized() {
+    return Modifier.isSynchronized(getModifiers());
+  }
+
+  /** Returns true if the field is volatile. */
+  final boolean isVolatile() {
+    return Modifier.isVolatile(getModifiers());
+  }
+
+  /** Returns true if the field is transient. */
+  final boolean isTransient() {
+    return Modifier.isTransient(getModifiers());
+  }
+
+  @Override
+  public boolean equals(@CheckForNull Object obj) {
+    if (obj instanceof Invokable) {
+      Invokable<?, ?> that = (Invokable<?, ?>) obj;
+      return getOwnerType().equals(that.getOwnerType()) && member.equals(that.member);
+    }
+    return false;
+  }
+
+  @Override
+  public int hashCode() {
+    return member.hashCode();
+  }
+
+  @Override
+  public String toString() {
+    return member.toString();
+  }
+
   /**
    * Returns {@code true} if this is an overridable method. Constructors, private, static or final
    * methods, or methods declared by final classes are not overridable.
@@ -94,10 +252,11 @@ public static <T> Invokable<T, T> from(Constructor<T> constructor) {
    *     invocation conversion.
    * @throws InvocationTargetException if the underlying method or constructor throws an exception.
    */
-  // All subclasses are owned by us and we'll make sure to get the R type right.
-  @SuppressWarnings("unchecked")
+  // All subclasses are owned by us and we'll make sure to get the R type right, including nullness.
+  @SuppressWarnings({"unchecked", "nullness"})
   @CanIgnoreReturnValue
-  public final R invoke(@Nullable T receiver, Object... args)
+  @CheckForNull
+  public final R invoke(@CheckForNull T receiver, @Nullable Object... args)
       throws InvocationTargetException, IllegalAccessException {
     return (R) invokeInternal(receiver, checkNotNull(args));
   }
@@ -166,18 +325,18 @@ public final <R1 extends R> Invokable<T, R1> returning(TypeToken<R1> returnType)
   @SuppressWarnings("unchecked") // The declaring class is T's raw class, or one of its supertypes.
   @Override
   public final Class<? super T> getDeclaringClass() {
-    return (Class<? super T>) super.getDeclaringClass();
+    return (Class<? super T>) member.getDeclaringClass();
   }
 
   /** Returns the type of {@code T}. */
   // Overridden in TypeToken#method() and TypeToken#constructor()
   @SuppressWarnings("unchecked") // The declaring class is T.
-  @Override
   public TypeToken<T> getOwnerType() {
     return (TypeToken<T>) TypeToken.of(getDeclaringClass());
   }
 
-  abstract Object invokeInternal(@Nullable Object receiver, Object[] args)
+  @CheckForNull
+  abstract Object invokeInternal(@CheckForNull Object receiver, @Nullable Object[] args)
       throws InvocationTargetException, IllegalAccessException;
 
   abstract Type[] getGenericParameterTypes();
@@ -203,7 +362,8 @@ static class MethodInvokable<T> extends Invokable<T, Object> {
     }
 
     @Override
-    final Object invokeInternal(@Nullable Object receiver, Object[] args)
+    @CheckForNull
+    final Object invokeInternal(@CheckForNull Object receiver, @Nullable Object[] args)
         throws InvocationTargetException, IllegalAccessException {
       return method.invoke(receiver, args);
     }
@@ -267,7 +427,7 @@ static class ConstructorInvokable<T> extends Invokable<T, T> {
     }
 
     @Override
-    final Object invokeInternal(@Nullable Object receiver, Object[] args)
+    final Object invokeInternal(@CheckForNull Object receiver, @Nullable Object[] args)
         throws InvocationTargetException, IllegalAccessException {
       try {
         return constructor.newInstance(args);
diff --git a/guava/src/com/google/common/reflect/MutableTypeToInstanceMap.java b/guava/src/com/google/common/reflect/MutableTypeToInstanceMap.java
index 2d21dbbcc7f8..9542e0a7ed51 100644
--- a/guava/src/com/google/common/reflect/MutableTypeToInstanceMap.java
+++ b/guava/src/com/google/common/reflect/MutableTypeToInstanceMap.java
@@ -16,8 +16,6 @@
 
 import static com.google.common.base.Preconditions.checkNotNull;
 
-import com.google.common.annotations.Beta;
-import com.google.common.base.Function;
 import com.google.common.collect.ForwardingMap;
 import com.google.common.collect.ForwardingMapEntry;
 import com.google.common.collect.ForwardingSet;
@@ -28,39 +26,47 @@
 import java.util.Iterator;
 import java.util.Map;
 import java.util.Set;
+import javax.annotation.CheckForNull;
 import org.checkerframework.checker.nullness.qual.Nullable;
 
 /**
  * A mutable type-to-instance map. See also {@link ImmutableTypeToInstanceMap}.
  *
+ * <p>This implementation <i>does</i> support null values, despite how it is annotated; see
+ * discussion at {@link TypeToInstanceMap}.
+ *
  * @author Ben Yu
  * @since 13.0
  */
-@Beta
+@ElementTypesAreNonnullByDefault
 public final class MutableTypeToInstanceMap<B> extends ForwardingMap<TypeToken<? extends B>, B>
     implements TypeToInstanceMap<B> {
 
   private final Map<TypeToken<? extends B>, B> backingMap = Maps.newHashMap();
 
   @Override
-  public <T extends B> @Nullable T getInstance(Class<T> type) {
+  @CheckForNull
+  public <T extends B> T getInstance(Class<T> type) {
     return trustedGet(TypeToken.of(type));
   }
 
   @Override
-  public <T extends B> @Nullable T getInstance(TypeToken<T> type) {
+  @CheckForNull
+  public <T extends B> T getInstance(TypeToken<T> type) {
     return trustedGet(type.rejectTypeVariables());
   }
 
   @Override
   @CanIgnoreReturnValue
-  public <T extends B> @Nullable T putInstance(Class<T> type, @Nullable T value) {
+  @CheckForNull
+  public <T extends B> T putInstance(Class<T> type, T value) {
     return trustedPut(TypeToken.of(type), value);
   }
 
   @Override
   @CanIgnoreReturnValue
-  public <T extends B> @Nullable T putInstance(TypeToken<T> type, @Nullable T value) {
+  @CheckForNull
+  public <T extends B> T putInstance(TypeToken<T> type, T value) {
     return trustedPut(type.rejectTypeVariables(), value);
   }
 
@@ -74,6 +80,7 @@ public final class MutableTypeToInstanceMap<B> extends ForwardingMap<TypeToken<?
   @Deprecated
   @Override
   @DoNotCall("Always throws UnsupportedOperationException")
+  @CheckForNull
   public B put(TypeToken<? extends B> key, B value) {
     throw new UnsupportedOperationException("Please use putInstance() instead.");
   }
@@ -102,12 +109,14 @@ protected Map<TypeToken<? extends B>, B> delegate() {
   }
 
   @SuppressWarnings("unchecked") // value could not get in if not a T
-  private <T extends B> @Nullable T trustedPut(TypeToken<T> type, @Nullable T value) {
+  @CheckForNull
+  private <T extends B> T trustedPut(TypeToken<T> type, T value) {
     return (T) backingMap.put(type, value);
   }
 
   @SuppressWarnings("unchecked") // value could not get in if not a T
-  private <T extends B> @Nullable T trustedGet(TypeToken<T> type) {
+  @CheckForNull
+  private <T extends B> T trustedGet(TypeToken<T> type) {
     return (T) backingMap.get(type);
   }
 
@@ -115,7 +124,7 @@ private static final class UnmodifiableEntry<K, V> extends ForwardingMapEntry<K,
 
     private final Entry<K, V> delegate;
 
-    static <K, V> Set<Entry<K, V>> transformEntries(final Set<Entry<K, V>> entries) {
+    static <K, V> Set<Entry<K, V>> transformEntries(Set<Entry<K, V>> entries) {
       return new ForwardingSet<Map.Entry<K, V>>() {
         @Override
         protected Set<Entry<K, V>> delegate() {
@@ -129,25 +138,27 @@ public Iterator<Entry<K, V>> iterator() {
 
         @Override
         public Object[] toArray() {
-          return standardToArray();
+          /*
+           * standardToArray returns `@Nullable Object[]` rather than `Object[]` but only because it
+           * can be used with collections that may contain null. This collection is a collection of
+           * non-null Entry objects (Entry objects that might contain null values but are not
+           * themselves null), so we can treat it as a plain `Object[]`.
+           */
+          @SuppressWarnings("nullness")
+          Object[] result = standardToArray();
+          return result;
         }
 
         @Override
-        public <T> T[] toArray(T[] array) {
+        @SuppressWarnings("nullness") // b/192354773 in our checker affects toArray declarations
+        public <T extends @Nullable Object> T[] toArray(T[] array) {
           return standardToArray(array);
         }
       };
     }
 
     private static <K, V> Iterator<Entry<K, V>> transformEntries(Iterator<Entry<K, V>> entries) {
-      return Iterators.transform(
-          entries,
-          new Function<Entry<K, V>, Entry<K, V>>() {
-            @Override
-            public Entry<K, V> apply(Entry<K, V> entry) {
-              return new UnmodifiableEntry<>(entry);
-            }
-          });
+      return Iterators.transform(entries, UnmodifiableEntry::new);
     }
 
     private UnmodifiableEntry(java.util.Map.Entry<K, V> delegate) {
diff --git a/guava/src/com/google/common/reflect/Parameter.java b/guava/src/com/google/common/reflect/Parameter.java
index 8065920c8f18..c3c46eca9d08 100644
--- a/guava/src/com/google/common/reflect/Parameter.java
+++ b/guava/src/com/google/common/reflect/Parameter.java
@@ -22,15 +22,21 @@
 import java.lang.annotation.Annotation;
 import java.lang.reflect.AnnotatedElement;
 import java.lang.reflect.AnnotatedType;
+import javax.annotation.CheckForNull;
 import org.checkerframework.checker.nullness.qual.Nullable;
 
 /**
  * Represents a method or constructor parameter.
  *
+ * <p><b>Note:</b> Since Java 8 introduced {@link java.lang.reflect.Parameter} to represent method
+ * and constructor parameters, this class is no longer necessary. We intend to deprecate it in a
+ * future version.
+ *
  * @author Ben Yu
  * @since 14.0
  */
 @Beta
+@ElementTypesAreNonnullByDefault
 public final class Parameter implements AnnotatedElement {
 
   private final Invokable<?, ?> declaration;
@@ -68,7 +74,8 @@ public boolean isAnnotationPresent(Class<? extends Annotation> annotationType) {
   }
 
   @Override
-  public <A extends Annotation> @Nullable A getAnnotation(Class<A> annotationType) {
+  @CheckForNull
+  public <A extends Annotation> A getAnnotation(Class<A> annotationType) {
     checkNotNull(annotationType);
     for (Annotation annotation : annotations) {
       if (annotationType.isInstance(annotation)) {
@@ -100,7 +107,8 @@ public Annotation[] getDeclaredAnnotations() {
   /** @since 18.0 */
   // @Override on JDK8
   @Override
-  public <A extends Annotation> @Nullable A getDeclaredAnnotation(Class<A> annotationType) {
+  @CheckForNull
+  public <A extends Annotation> A getDeclaredAnnotation(Class<A> annotationType) {
     checkNotNull(annotationType);
     return FluentIterable.from(annotations).filter(annotationType).first().orNull();
   }
@@ -109,7 +117,11 @@ public Annotation[] getDeclaredAnnotations() {
   // @Override on JDK8
   @Override
   public <A extends Annotation> A[] getDeclaredAnnotationsByType(Class<A> annotationType) {
-    return FluentIterable.from(annotations).filter(annotationType).toArray(annotationType);
+    @Nullable
+    A[] result = FluentIterable.from(annotations).filter(annotationType).toArray(annotationType);
+    @SuppressWarnings("nullness") // safe because the input list contains no nulls
+    A[] cast = (A[]) result;
+    return cast;
   }
 
   /** @since 25.1 */
@@ -119,7 +131,7 @@ public AnnotatedType getAnnotatedType() {
   }
 
   @Override
-  public boolean equals(@Nullable Object obj) {
+  public boolean equals(@CheckForNull Object obj) {
     if (obj instanceof Parameter) {
       Parameter that = (Parameter) obj;
       return position == that.position && declaration.equals(that.declaration);
diff --git a/guava/src/com/google/common/reflect/ParametricNullness.java b/guava/src/com/google/common/reflect/ParametricNullness.java
new file mode 100644
index 000000000000..b6331ac26b0b
--- /dev/null
+++ b/guava/src/com/google/common/reflect/ParametricNullness.java
@@ -0,0 +1,52 @@
+/*
+ * Copyright (C) 2021 The Guava Authors
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package com.google.common.reflect;
+
+import static java.lang.annotation.ElementType.FIELD;
+import static java.lang.annotation.ElementType.METHOD;
+import static java.lang.annotation.ElementType.PARAMETER;
+import static java.lang.annotation.RetentionPolicy.RUNTIME;
+
+import com.google.common.annotations.GwtCompatible;
+import java.lang.annotation.Retention;
+import java.lang.annotation.Target;
+
+/**
+ * Marks a "top-level" type-variable usage as the closest we can get to "non-nullable when
+ * non-nullable; nullable when nullable" (like the Android <a
+ * href="https://android.googlesource.com/platform/libcore/+/master/luni/src/main/java/libcore/util/NullFromTypeParam.java">{@code
+ * NullFromTypeParam}</a>).
+ *
+ * <p>Consumers of this annotation include:
+ *
+ * <ul>
+ *   <li>Kotlin, for which it makes the type-variable usage (a) a Kotlin platform type when the type
+ *       argument is non-nullable and (b) nullable when the type argument is nullable. We use this
+ *       to "undo" {@link ElementTypesAreNonnullByDefault}.
+ *   <li><a href="https://developers.google.com/j2objc">J2ObjC</a>
+ *   <li>{@code NullPointerTester}, at least in the Android backport (where the type-use annotations
+ *       {@code NullPointerTester} would need are not available) and in case of <a
+ *       href="https://bugs.openjdk.java.net/browse/JDK-8202469">JDK-8202469</a>
+ * </ul>
+ *
+ */
+@GwtCompatible
+@Retention(RUNTIME)
+@Target({FIELD, METHOD, PARAMETER})
+@javax.annotation.meta.TypeQualifierNickname
+@javax.annotation.Nonnull(when = javax.annotation.meta.When.UNKNOWN)
+@interface ParametricNullness {}
diff --git a/guava/src/com/google/common/reflect/Reflection.java b/guava/src/com/google/common/reflect/Reflection.java
index 4ad5dff78a72..9544963481d9 100644
--- a/guava/src/com/google/common/reflect/Reflection.java
+++ b/guava/src/com/google/common/reflect/Reflection.java
@@ -17,7 +17,6 @@
 import static com.google.common.base.Preconditions.checkArgument;
 import static com.google.common.base.Preconditions.checkNotNull;
 
-import com.google.common.annotations.Beta;
 import java.lang.reflect.InvocationHandler;
 import java.lang.reflect.Proxy;
 
@@ -26,7 +25,7 @@
  *
  * @since 12.0
  */
-@Beta
+@ElementTypesAreNonnullByDefault
 public final class Reflection {
 
   /**
diff --git a/guava/src/com/google/common/reflect/TypeCapture.java b/guava/src/com/google/common/reflect/TypeCapture.java
index effb382b2826..2be7b4fddad1 100644
--- a/guava/src/com/google/common/reflect/TypeCapture.java
+++ b/guava/src/com/google/common/reflect/TypeCapture.java
@@ -24,6 +24,7 @@
  *
  * @author Ben Yu
  */
+@ElementTypesAreNonnullByDefault
 abstract class TypeCapture<T> {
 
   /** Returns the captured type. */
diff --git a/guava/src/com/google/common/reflect/TypeParameter.java b/guava/src/com/google/common/reflect/TypeParameter.java
index 586c912ae857..69cd8291a909 100644
--- a/guava/src/com/google/common/reflect/TypeParameter.java
+++ b/guava/src/com/google/common/reflect/TypeParameter.java
@@ -16,10 +16,9 @@
 
 import static com.google.common.base.Preconditions.checkArgument;
 
-import com.google.common.annotations.Beta;
 import java.lang.reflect.Type;
 import java.lang.reflect.TypeVariable;
-import org.checkerframework.checker.nullness.qual.Nullable;
+import javax.annotation.CheckForNull;
 
 /**
  * Captures a free type variable that can be used in {@link TypeToken#where}. For example:
@@ -34,7 +33,17 @@
  * @author Ben Yu
  * @since 12.0
  */
-@Beta
+@ElementTypesAreNonnullByDefault
+/*
+ * A nullable bound would let users create a TypeParameter instance for a parameter with a nullable
+ * bound. However, it would also let them create `new TypeParameter<@Nullable T>() {}`, which
+ * wouldn't behave as users might expect. Additionally, it's not clear how the TypeToken API could
+ * support even a "normal" `TypeParameter<T>` when `<T>` has a nullable bound. (See the discussion
+ * on TypeToken.where.) So, in the interest of failing fast and encouraging the user to switch to a
+ * non-null bound if possible, let's require a non-null bound here.
+ *
+ * TODO(cpovirk): Elaborate on "wouldn't behave as users might expect."
+ */
 public abstract class TypeParameter<T> extends TypeCapture<T> {
 
   final TypeVariable<?> typeVariable;
@@ -51,7 +60,7 @@ public final int hashCode() {
   }
 
   @Override
-  public final boolean equals(@Nullable Object o) {
+  public final boolean equals(@CheckForNull Object o) {
     if (o instanceof TypeParameter) {
       TypeParameter<?> that = (TypeParameter<?>) o;
       return typeVariable.equals(that.typeVariable);
diff --git a/guava/src/com/google/common/reflect/TypeResolver.java b/guava/src/com/google/common/reflect/TypeResolver.java
index 339eb43b5850..32517eb8782f 100644
--- a/guava/src/com/google/common/reflect/TypeResolver.java
+++ b/guava/src/com/google/common/reflect/TypeResolver.java
@@ -19,7 +19,6 @@
 import static com.google.common.base.Preconditions.checkState;
 import static java.util.Arrays.asList;
 
-import com.google.common.annotations.Beta;
 import com.google.common.base.Joiner;
 import com.google.common.base.Objects;
 import com.google.common.collect.ImmutableMap;
@@ -35,7 +34,7 @@
 import java.util.Map.Entry;
 import java.util.Set;
 import java.util.concurrent.atomic.AtomicInteger;
-import org.checkerframework.checker.nullness.qual.Nullable;
+import javax.annotation.CheckForNull;
 
 /**
  * An object of this class encapsulates type mappings from type variables. Mappings are established
@@ -51,7 +50,7 @@
  * @author Ben Yu
  * @since 15.0
  */
-@Beta
+@ElementTypesAreNonnullByDefault
 public final class TypeResolver {
 
   private final TypeTable typeTable;
@@ -122,7 +121,7 @@ TypeResolver where(Map<TypeVariableKey, ? extends Type> mappings) {
   }
 
   private static void populateTypeMappings(
-      final Map<TypeVariableKey, Type> mappings, final Type from, final Type to) {
+      Map<TypeVariableKey, Type> mappings, Type from, Type to) {
     if (from.equals(to)) {
       return;
     }
@@ -295,11 +294,11 @@ final TypeTable where(Map<TypeVariableKey, ? extends Type> mappings) {
         checkArgument(!variable.equalsType(type), "Type variable %s bound to itself", variable);
         builder.put(variable, type);
       }
-      return new TypeTable(builder.build());
+      return new TypeTable(builder.buildOrThrow());
     }
 
-    final Type resolve(final TypeVariable<?> var) {
-      final TypeTable unguarded = this;
+    final Type resolve(TypeVariable<?> var) {
+      TypeTable unguarded = this;
       TypeTable guarded =
           new TypeTable() {
             @Override
@@ -413,7 +412,7 @@ void visitWildcardType(WildcardType t) {
       visit(t.getUpperBounds());
     }
 
-    private void map(final TypeVariableKey var, final Type arg) {
+    private void map(TypeVariableKey var, Type arg) {
       if (mappings.containsKey(var)) {
         // Mapping already established
         // This is possible when following both superClass -> enclosingClass
@@ -503,12 +502,12 @@ TypeVariable<?> captureAsTypeVariable(Type[] upperBounds) {
       return Types.newArtificialTypeVariable(WildcardCapturer.class, name, upperBounds);
     }
 
-    private WildcardCapturer forTypeVariable(final TypeVariable<?> typeParam) {
+    private WildcardCapturer forTypeVariable(TypeVariable<?> typeParam) {
       return new WildcardCapturer(id) {
         @Override
         TypeVariable<?> captureAsTypeVariable(Type[] upperBounds) {
           Set<Type> combined = new LinkedHashSet<>(asList(upperBounds));
-          // Since this is an artifically generated type variable, we don't bother checking
+          // Since this is an artificially generated type variable, we don't bother checking
           // subtyping between declared type bound and actual type bound. So it's possible that we
           // may generate something like <capture#1-of ? extends Foo&SubFoo>.
           // Checking subtype between declared and actual type bounds
@@ -527,7 +526,8 @@ private WildcardCapturer notForTypeVariable() {
       return new WildcardCapturer(id);
     }
 
-    private Type captureNullable(@Nullable Type type) {
+    @CheckForNull
+    private Type captureNullable(@CheckForNull Type type) {
       if (type == null) {
         return null;
       }
@@ -561,7 +561,7 @@ public int hashCode() {
     }
 
     @Override
-    public boolean equals(Object obj) {
+    public boolean equals(@CheckForNull Object obj) {
       if (obj instanceof TypeVariableKey) {
         TypeVariableKey that = (TypeVariableKey) obj;
         return equalsTypeVariable(that.var);
@@ -576,6 +576,7 @@ public String toString() {
     }
 
     /** Wraps {@code t} in a {@code TypeVariableKey} if it's a type variable. */
+    @CheckForNull
     static TypeVariableKey forLookup(Type t) {
       if (t instanceof TypeVariable) {
         return new TypeVariableKey((TypeVariable<?>) t);
diff --git a/guava/src/com/google/common/reflect/TypeToInstanceMap.java b/guava/src/com/google/common/reflect/TypeToInstanceMap.java
index 443b2580cfc5..8a418df2a4d3 100644
--- a/guava/src/com/google/common/reflect/TypeToInstanceMap.java
+++ b/guava/src/com/google/common/reflect/TypeToInstanceMap.java
@@ -14,11 +14,10 @@
 
 package com.google.common.reflect;
 
-import com.google.common.annotations.Beta;
 import com.google.errorprone.annotations.CanIgnoreReturnValue;
 import com.google.errorprone.annotations.DoNotMock;
 import java.util.Map;
-import org.checkerframework.checker.nullness.qual.Nullable;
+import javax.annotation.CheckForNull;
 
 /**
  * A map, each entry of which maps a {@link TypeToken} to an instance of that type. In addition to
@@ -35,12 +34,15 @@
  * <p>Like any other {@code Map<Class, Object>}, this map may contain entries for primitive types,
  * and a primitive type and its corresponding wrapper type may map to different values.
  *
+ * <p>This class's support for {@code null} requires some explanation. For details, see {@link
+ * ClassToInstanceMap}. Its explanation applies equally well to {@code TypeToInstanceMap}.
+ *
  * @param <B> the common supertype that all entries must share; often this is simply {@link Object}
  * @author Ben Yu
  * @since 13.0
  */
-@Beta
 @DoNotMock("Use ImmutableTypeToInstanceMap or MutableTypeToInstanceMap")
+@ElementTypesAreNonnullByDefault
 public interface TypeToInstanceMap<B> extends Map<TypeToken<? extends B>, B> {
 
   /**
@@ -51,14 +53,16 @@ public interface TypeToInstanceMap<B> extends Map<TypeToken<? extends B>, B> {
    * <p>{@code getInstance(Foo.class)} is equivalent to {@code
    * getInstance(TypeToken.of(Foo.class))}.
    */
-  <T extends B> @Nullable T getInstance(Class<T> type);
+  @CheckForNull
+  <T extends B> T getInstance(Class<T> type);
 
   /**
    * Returns the value the specified type is mapped to, or {@code null} if no entry for this type is
    * present. This will only return a value that was bound to this specific type, not a value that
    * may have been bound to a subtype.
    */
-  <T extends B> @Nullable T getInstance(TypeToken<T> type);
+  @CheckForNull
+  <T extends B> T getInstance(TypeToken<T> type);
 
   /**
    * Maps the specified class to the specified value. Does <i>not</i> associate this value with any
@@ -71,7 +75,8 @@ public interface TypeToInstanceMap<B> extends Map<TypeToken<? extends B>, B> {
    *     null} if there was no previous entry.
    */
   @CanIgnoreReturnValue
-  <T extends B> @Nullable T putInstance(Class<T> type, @Nullable T value);
+  @CheckForNull
+  <T extends B> T putInstance(Class<T> type, T value);
 
   /**
    * Maps the specified type to the specified value. Does <i>not</i> associate this value with any
@@ -81,5 +86,6 @@ public interface TypeToInstanceMap<B> extends Map<TypeToken<? extends B>, B> {
    *     if there was no previous entry.
    */
   @CanIgnoreReturnValue
-  <T extends B> @Nullable T putInstance(TypeToken<T> type, @Nullable T value);
+  @CheckForNull
+  <T extends B> T putInstance(TypeToken<T> type, T value);
 }
diff --git a/guava/src/com/google/common/reflect/TypeToken.java b/guava/src/com/google/common/reflect/TypeToken.java
index 88deff3f4f10..fea1d53a2fab 100644
--- a/guava/src/com/google/common/reflect/TypeToken.java
+++ b/guava/src/com/google/common/reflect/TypeToken.java
@@ -17,6 +17,7 @@
 import static com.google.common.base.Preconditions.checkArgument;
 import static com.google.common.base.Preconditions.checkNotNull;
 import static com.google.common.base.Preconditions.checkState;
+import static java.util.Objects.requireNonNull;
 
 import com.google.common.annotations.Beta;
 import com.google.common.annotations.VisibleForTesting;
@@ -46,7 +47,7 @@
 import java.util.List;
 import java.util.Map;
 import java.util.Set;
-import org.checkerframework.checker.nullness.qual.Nullable;
+import javax.annotation.CheckForNull;
 
 /**
  * A {@link Type} with generics.
@@ -96,17 +97,17 @@
  * @author Ben Yu
  * @since 12.0
  */
-@Beta
 @SuppressWarnings("serial") // SimpleTypeToken is the serialized form.
+@ElementTypesAreNonnullByDefault
 public abstract class TypeToken<T> extends TypeCapture<T> implements Serializable {
 
   private final Type runtimeType;
 
   /** Resolver for resolving parameter and field types with {@link #runtimeType} as context. */
-  private transient @Nullable TypeResolver invariantTypeResolver;
+  @CheckForNull private transient TypeResolver invariantTypeResolver;
 
   /** Resolver for resolving covariant types with {@link #runtimeType} as context. */
-  private transient @Nullable TypeResolver covariantTypeResolver;
+  @CheckForNull private transient TypeResolver covariantTypeResolver;
 
   /**
    * Constructs a new type token of {@code T}.
@@ -166,7 +167,7 @@ private TypeToken(Type type) {
 
   /** Returns an instance of type token that wraps {@code type}. */
   public static <T> TypeToken<T> of(Class<T> type) {
-    return new SimpleTypeToken<T>(type);
+    return new SimpleTypeToken<>(type);
   }
 
   /** Returns an instance of type token that wraps {@code type}. */
@@ -220,6 +221,17 @@ public final Type getType() {
    * @param typeParam the parameter type variable
    * @param typeArg the actual type to substitute
    */
+  /*
+   * TODO(cpovirk): Is there any way for us to support TypeParameter instances for type parameters
+   * that have nullable bounds? Unfortunately, if we change the parameter to TypeParameter<? extends
+   * @Nullable X>, then users might pass a TypeParameter<Y>, where Y is a subtype of X, while still
+   * passing a TypeToken<X>. This would be invalid. Maybe we could accept a TypeParameter<@PolyNull
+   * X> if we support such a thing? It would be weird or misleading for users to be able to pass
+   * `new TypeParameter<@Nullable T>() {}` and have it act as a plain `TypeParameter<T>`, but
+   * hopefully no one would do that, anyway. See also the comment on TypeParameter itself.
+   *
+   * TODO(cpovirk): Elaborate on this / merge with other comment?
+   */
   public final <X> TypeToken<T> where(TypeParameter<X> typeParam, TypeToken<X> typeArg) {
     TypeResolver resolver =
         new TypeResolver()
@@ -227,7 +239,7 @@ public final <X> TypeToken<T> where(TypeParameter<X> typeParam, TypeToken<X> typ
                 ImmutableMap.of(
                     new TypeResolver.TypeVariableKey(typeParam.typeVariable), typeArg.runtimeType));
     // If there's any type error, we'd report now rather than later.
-    return new SimpleTypeToken<T>(resolver.resolveType(runtimeType));
+    return new SimpleTypeToken<>(resolver.resolveType(runtimeType));
   }
 
   /**
@@ -248,6 +260,10 @@ public final <X> TypeToken<T> where(TypeParameter<X> typeParam, TypeToken<X> typ
    * @param typeParam the parameter type variable
    * @param typeArg the actual type to substitute
    */
+  /*
+   * TODO(cpovirk): Is there any way for us to support TypeParameter instances for type parameters
+   * that have nullable bounds? See discussion on the other overload of this method.
+   */
   public final <X> TypeToken<T> where(TypeParameter<X> typeParam, Class<X> typeArg) {
     return where(typeParam, of(typeArg));
   }
@@ -288,7 +304,8 @@ private TypeToken<?> resolveSupertype(Type type) {
    * if the bound is a class or extends from a class. This means that the returned type could be a
    * type variable too.
    */
-  final @Nullable TypeToken<? super T> getGenericSuperclass() {
+  @CheckForNull
+  final TypeToken<? super T> getGenericSuperclass() {
     if (runtimeType instanceof TypeVariable) {
       // First bound is always the super class, if one exists.
       return boundAsSuperclass(((TypeVariable<?>) runtimeType).getBounds()[0]);
@@ -306,7 +323,8 @@ private TypeToken<?> resolveSupertype(Type type) {
     return superToken;
   }
 
-  private @Nullable TypeToken<? super T> boundAsSuperclass(Type bound) {
+  @CheckForNull
+  private TypeToken<? super T> boundAsSuperclass(Type bound) {
     TypeToken<?> token = of(bound);
     if (token.getRawType().isInterface()) {
       return null;
@@ -558,7 +576,8 @@ public final TypeToken<T> unwrap() {
    * Returns the array component type if this type represents an array ({@code int[]}, {@code T[]},
    * {@code <? extends Map<String, Integer>[]>} etc.), or else {@code null} is returned.
    */
-  public final @Nullable TypeToken<?> getComponentType() {
+  @CheckForNull
+  public final TypeToken<?> getComponentType() {
     Type componentType = Types.getComponentType(runtimeType);
     if (componentType == null) {
       return null;
@@ -571,6 +590,7 @@ public final TypeToken<T> unwrap() {
    *
    * @since 14.0
    */
+  @Beta
   public final Invokable<T, Object> method(Method method) {
     checkArgument(
         this.someRawTypeIsSubclassOf(method.getDeclaringClass()),
@@ -610,6 +630,7 @@ public String toString() {
    *
    * @since 14.0
    */
+  @Beta
   public final Invokable<T, T> constructor(Constructor<?> constructor) {
     checkArgument(
         constructor.getDeclaringClass() == getRawType(),
@@ -652,7 +673,7 @@ public String toString() {
    */
   public class TypeSet extends ForwardingSet<TypeToken<? super T>> implements Serializable {
 
-    private transient @Nullable ImmutableSet<TypeToken<? super T>> types;
+    @CheckForNull private transient ImmutableSet<TypeToken<? super T>> types;
 
     TypeSet() {}
 
@@ -698,7 +719,7 @@ public Set<Class<? super T>> rawTypes() {
   private final class InterfaceSet extends TypeSet {
 
     private final transient TypeSet allTypes;
-    private transient @Nullable ImmutableSet<TypeToken<? super T>> interfaces;
+    @CheckForNull private transient ImmutableSet<TypeToken<? super T>> interfaces;
 
     InterfaceSet(TypeSet allTypes) {
       this.allTypes = allTypes;
@@ -726,15 +747,7 @@ public Set<Class<? super T>> rawTypes() {
       @SuppressWarnings({"unchecked", "rawtypes"})
       ImmutableList<Class<? super T>> collectedTypes =
           (ImmutableList) TypeCollector.FOR_RAW_TYPE.collectTypes(getRawTypes());
-      return FluentIterable.from(collectedTypes)
-          .filter(
-              new Predicate<Class<?>>() {
-                @Override
-                public boolean apply(Class<?> type) {
-                  return type.isInterface();
-                }
-              })
-          .toSet();
+      return FluentIterable.from(collectedTypes).filter(Class::isInterface).toSet();
     }
 
     @Override
@@ -751,7 +764,7 @@ private Object readResolve() {
 
   private final class ClassSet extends TypeSet {
 
-    private transient @Nullable ImmutableSet<TypeToken<? super T>> classes;
+    @CheckForNull private transient ImmutableSet<TypeToken<? super T>> classes;
 
     @Override
     protected Set<TypeToken<? super T>> delegate() {
@@ -816,7 +829,7 @@ public boolean apply(TypeToken<?> type) {
    * Returns true if {@code o} is another {@code TypeToken} that represents the same {@link Type}.
    */
   @Override
-  public boolean equals(@Nullable Object o) {
+  public boolean equals(@CheckForNull Object o) {
     if (o instanceof TypeToken) {
       TypeToken<?> that = (TypeToken<?>) o;
       return runtimeType.equals(that.runtimeType);
@@ -1083,7 +1096,7 @@ boolean isSupertypeOf(Type subtype) {
   }
 
   private ImmutableSet<Class<? super T>> getRawTypes() {
-    final ImmutableSet.Builder<Class<?>> builder = ImmutableSet.builder();
+    ImmutableSet.Builder<Class<?>> builder = ImmutableSet.builder();
     new TypeVisitor() {
       @Override
       void visitTypeVariable(TypeVariable<?> t) {
@@ -1130,7 +1143,8 @@ private boolean isOwnedBySubtypeOf(Type supertype) {
    * Returns the owner type of a {@link ParameterizedType} or enclosing class of a {@link Class}, or
    * null otherwise.
    */
-  private @Nullable Type getOwnerTypeIfPresent() {
+  @CheckForNull
+  private Type getOwnerTypeIfPresent() {
     if (runtimeType instanceof ParameterizedType) {
       return ((ParameterizedType) runtimeType).getOwnerType();
     } else if (runtimeType instanceof Class<?>) {
@@ -1219,11 +1233,19 @@ private TypeToken<? super T> getArraySupertype(Class<? super T> supertype) {
     // with component type, we have lost generic type information
     // Use raw type so that compiler allows us to call getSupertype()
     @SuppressWarnings("rawtypes")
-    TypeToken componentType =
-        checkNotNull(getComponentType(), "%s isn't a super type of %s", supertype, this);
+    TypeToken componentType = getComponentType();
+    // TODO(cpovirk): checkArgument?
+    if (componentType == null) {
+      throw new IllegalArgumentException(supertype + " isn't a super type of " + this);
+    }
     // array is covariant. component type is super type, so is the array type.
     @SuppressWarnings("unchecked") // going from raw type back to generics
-    TypeToken<?> componentSupertype = componentType.getSupertype(supertype.getComponentType());
+    /*
+     * requireNonNull is safe because we call getArraySupertype only after checking
+     * supertype.isArray().
+     */
+    TypeToken<?> componentSupertype =
+        componentType.getSupertype(requireNonNull(supertype.getComponentType()));
     @SuppressWarnings("unchecked") // component type is super type, so is array type.
     TypeToken<? super T> result =
         (TypeToken<? super T>)
@@ -1233,8 +1255,14 @@ private TypeToken<? super T> getArraySupertype(Class<? super T> supertype) {
   }
 
   private TypeToken<? extends T> getArraySubtype(Class<?> subclass) {
+    Class<?> subclassComponentType = subclass.getComponentType();
+    if (subclassComponentType == null) {
+      throw new IllegalArgumentException(subclass + " does not appear to be a subtype of " + this);
+    }
     // array is covariant. component type is subtype, so is the array type.
-    TypeToken<?> componentSubtype = getComponentType().getSubtype(subclass.getComponentType());
+    // requireNonNull is safe because we call getArraySubtype only when isArray().
+    TypeToken<?> componentSubtype =
+        requireNonNull(getComponentType()).getSubtype(subclassComponentType);
     @SuppressWarnings("unchecked") // component type is subtype, so is array type.
     TypeToken<? extends T> result =
         (TypeToken<? extends T>)
@@ -1307,7 +1335,7 @@ Iterable<? extends TypeToken<?>> getInterfaces(TypeToken<?> type) {
           }
 
           @Override
-          @Nullable
+          @CheckForNull
           TypeToken<?> getSuperclass(TypeToken<?> type) {
             return type.getGenericSuperclass();
           }
@@ -1326,7 +1354,7 @@ Iterable<? extends Class<?>> getInterfaces(Class<?> type) {
           }
 
           @Override
-          @Nullable
+          @CheckForNull
           Class<?> getSuperclass(Class<?> type) {
             return type.getSuperclass();
           }
@@ -1393,12 +1421,14 @@ private int collectTypes(K type, Map<? super K, Integer> map) {
     }
 
     private static <K, V> ImmutableList<K> sortKeysByValue(
-        final Map<K, V> map, final Comparator<? super V> valueComparator) {
+        Map<K, V> map, Comparator<? super V> valueComparator) {
       Ordering<K> keyOrdering =
           new Ordering<K>() {
             @Override
             public int compare(K left, K right) {
-              return valueComparator.compare(map.get(left), map.get(right));
+              // requireNonNull is safe because we are passing keys in the map.
+              return valueComparator.compare(
+                  requireNonNull(map.get(left)), requireNonNull(map.get(right)));
             }
           };
       return keyOrdering.immutableSortedCopy(map.keySet());
@@ -1408,7 +1438,8 @@ public int compare(K left, K right) {
 
     abstract Iterable<? extends K> getInterfaces(K type);
 
-    abstract @Nullable K getSuperclass(K type);
+    @CheckForNull
+    abstract K getSuperclass(K type);
 
     private static class ForwardingTypeCollector<K> extends TypeCollector<K> {
 
@@ -1429,6 +1460,7 @@ Iterable<? extends K> getInterfaces(K type) {
       }
 
       @Override
+      @CheckForNull
       K getSuperclass(K type) {
         return delegate.getSuperclass(type);
       }
diff --git a/guava/src/com/google/common/reflect/TypeVisitor.java b/guava/src/com/google/common/reflect/TypeVisitor.java
index 3e8436dad189..416397bc77d6 100644
--- a/guava/src/com/google/common/reflect/TypeVisitor.java
+++ b/guava/src/com/google/common/reflect/TypeVisitor.java
@@ -21,6 +21,7 @@
 import java.lang.reflect.TypeVariable;
 import java.lang.reflect.WildcardType;
 import java.util.Set;
+import org.checkerframework.checker.nullness.qual.Nullable;
 
 /**
  * Based on what a {@link Type} is, dispatch it to the corresponding {@code visit*} method. By
@@ -53,6 +54,7 @@
  *
  * @author Ben Yu
  */
+@ElementTypesAreNonnullByDefault
 abstract class TypeVisitor {
 
   private final Set<Type> visited = Sets.newHashSet();
@@ -61,7 +63,7 @@ abstract class TypeVisitor {
    * Visits the given types. Null types are ignored. This allows subclasses to call {@code
    * visit(parameterizedType.getOwnerType())} safely without having to check nulls.
    */
-  public final void visit(Type... types) {
+  public final void visit(@Nullable Type... types) {
     for (Type type : types) {
       if (type == null || !visited.add(type)) {
         // null owner type, or already visited;
diff --git a/guava/src/com/google/common/reflect/Types.java b/guava/src/com/google/common/reflect/Types.java
index 42a1f7883db3..ef7dd5ad2c42 100644
--- a/guava/src/com/google/common/reflect/Types.java
+++ b/guava/src/com/google/common/reflect/Types.java
@@ -17,9 +17,9 @@
 import static com.google.common.base.Preconditions.checkArgument;
 import static com.google.common.base.Preconditions.checkNotNull;
 import static com.google.common.collect.Iterables.transform;
+import static java.util.Objects.requireNonNull;
 
 import com.google.common.annotations.VisibleForTesting;
-import com.google.common.base.Function;
 import com.google.common.base.Joiner;
 import com.google.common.base.Objects;
 import com.google.common.base.Predicates;
@@ -44,24 +44,19 @@
 import java.util.Collection;
 import java.util.Map.Entry;
 import java.util.concurrent.atomic.AtomicReference;
+import javax.annotation.CheckForNull;
 import org.checkerframework.checker.nullness.qual.Nullable;
+import org.checkerframework.common.value.qual.MinLen;
 
 /**
  * Utilities for working with {@link Type}.
  *
  * @author Ben Yu
  */
+@ElementTypesAreNonnullByDefault
 final class Types {
 
   /** Class#toString without the "class " and "interface " prefixes */
-  private static final Function<Type, String> TYPE_NAME =
-      new Function<Type, String>() {
-        @Override
-        public String apply(Type from) {
-          return JavaVersion.CURRENT.typeName(from);
-        }
-      };
-
   private static final Joiner COMMA_JOINER = Joiner.on(", ").useForNull("null");
 
   /** Returns the array type of {@code componentType}. */
@@ -86,7 +81,7 @@ static Type newArrayType(Type componentType) {
    * {@code ownerType}.
    */
   static ParameterizedType newParameterizedTypeWithOwner(
-      @Nullable Type ownerType, Class<?> rawType, Type... arguments) {
+      @CheckForNull Type ownerType, Class<?> rawType, Type... arguments) {
     if (ownerType == null) {
       return newParameterizedType(rawType, arguments);
     }
@@ -106,14 +101,14 @@ static ParameterizedType newParameterizedType(Class<?> rawType, Type... argument
   private enum ClassOwnership {
     OWNED_BY_ENCLOSING_CLASS {
       @Override
-      @Nullable
+      @CheckForNull
       Class<?> getOwnerType(Class<?> rawType) {
         return rawType.getEnclosingClass();
       }
     },
     LOCAL_CLASS_HAS_NO_OWNER {
       @Override
-      @Nullable
+      @CheckForNull
       Class<?> getOwnerType(Class<?> rawType) {
         if (rawType.isLocalClass()) {
           return null;
@@ -123,14 +118,17 @@ Class<?> getOwnerType(Class<?> rawType) {
       }
     };
 
-    abstract @Nullable Class<?> getOwnerType(Class<?> rawType);
+    @CheckForNull
+    abstract Class<?> getOwnerType(Class<?> rawType);
 
     static final ClassOwnership JVM_BEHAVIOR = detectJvmBehavior();
 
     private static ClassOwnership detectJvmBehavior() {
       class LocalClass<T> {}
       Class<?> subclass = new LocalClass<String>() {}.getClass();
-      ParameterizedType parameterizedType = (ParameterizedType) subclass.getGenericSuperclass();
+      // requireNonNull is safe because we're examining a type that's known to have a superclass.
+      ParameterizedType parameterizedType =
+          requireNonNull((ParameterizedType) subclass.getGenericSuperclass());
       for (ClassOwnership behavior : ClassOwnership.values()) {
         if (behavior.getOwnerType(LocalClass.class) == parameterizedType.getOwnerType()) {
           return behavior;
@@ -171,9 +169,10 @@ static String toString(Type type) {
     return (type instanceof Class) ? ((Class<?>) type).getName() : type.toString();
   }
 
-  static @Nullable Type getComponentType(Type type) {
+  @CheckForNull
+  static Type getComponentType(Type type) {
     checkNotNull(type);
-    final AtomicReference<Type> result = new AtomicReference<>();
+    AtomicReference<@Nullable Type> result = new AtomicReference<>();
     new TypeVisitor() {
       @Override
       void visitTypeVariable(TypeVariable<?> t) {
@@ -202,7 +201,8 @@ void visitClass(Class<?> t) {
    * Returns {@code ? extends X} if any of {@code bounds} is a subtype of {@code X[]}; or null
    * otherwise.
    */
-  private static @Nullable Type subtypeOfComponentType(Type[] bounds) {
+  @CheckForNull
+  private static Type subtypeOfComponentType(Type[] bounds) {
     for (Type bound : bounds) {
       Type componentType = getComponentType(bound);
       if (componentType != null) {
@@ -244,7 +244,7 @@ public int hashCode() {
     }
 
     @Override
-    public boolean equals(Object obj) {
+    public boolean equals(@CheckForNull Object obj) {
       if (obj instanceof GenericArrayType) {
         GenericArrayType that = (GenericArrayType) obj;
         return Objects.equal(getGenericComponentType(), that.getGenericComponentType());
@@ -257,11 +257,11 @@ public boolean equals(Object obj) {
 
   private static final class ParameterizedTypeImpl implements ParameterizedType, Serializable {
 
-    private final @Nullable Type ownerType;
+    @CheckForNull private final Type ownerType;
     private final ImmutableList<Type> argumentsList;
     private final Class<?> rawType;
 
-    ParameterizedTypeImpl(@Nullable Type ownerType, Class<?> rawType, Type[] typeArguments) {
+    ParameterizedTypeImpl(@CheckForNull Type ownerType, Class<?> rawType, Type[] typeArguments) {
       checkNotNull(rawType);
       checkArgument(typeArguments.length == rawType.getTypeParameters().length);
       disallowPrimitiveType(typeArguments, "type parameter");
@@ -281,6 +281,7 @@ public Type getRawType() {
     }
 
     @Override
+    @CheckForNull
     public Type getOwnerType() {
       return ownerType;
     }
@@ -294,7 +295,7 @@ public String toString() {
       return builder
           .append(rawType.getName())
           .append('<')
-          .append(COMMA_JOINER.join(transform(argumentsList, TYPE_NAME)))
+          .append(COMMA_JOINER.join(transform(argumentsList, JavaVersion.CURRENT::typeName)))
           .append('>')
           .toString();
     }
@@ -307,7 +308,7 @@ public int hashCode() {
     }
 
     @Override
-    public boolean equals(Object other) {
+    public boolean equals(@CheckForNull Object other) {
       if (!(other instanceof ParameterizedType)) {
         return false;
       }
@@ -322,8 +323,7 @@ public boolean equals(Object other) {
 
   private static <D extends GenericDeclaration> TypeVariable<D> newTypeVariableImpl(
       D genericDeclaration, String name, Type[] bounds) {
-    TypeVariableImpl<D> typeVariableImpl =
-        new TypeVariableImpl<D>(genericDeclaration, name, bounds);
+    TypeVariableImpl<D> typeVariableImpl = new TypeVariableImpl<>(genericDeclaration, name, bounds);
     @SuppressWarnings("unchecked")
     TypeVariable<D> typeVariable =
         Reflection.newProxy(
@@ -373,7 +373,7 @@ private static final class TypeVariableInvocationHandler implements InvocationHa
           builder.put(method.getName(), method);
         }
       }
-      typeVariableMethods = builder.build();
+      typeVariableMethods = builder.buildKeepingLast();
     }
 
     private final TypeVariableImpl<?> typeVariableImpl;
@@ -383,7 +383,9 @@ private static final class TypeVariableInvocationHandler implements InvocationHa
     }
 
     @Override
-    public Object invoke(Object proxy, Method method, Object[] args) throws Throwable {
+    @CheckForNull
+    public Object invoke(Object proxy, Method method, @CheckForNull @Nullable Object[] args)
+        throws Throwable {
       String methodName = method.getName();
       Method typeVariableMethod = typeVariableMethods.get(methodName);
       if (typeVariableMethod == null) {
@@ -438,7 +440,7 @@ public int hashCode() {
     }
 
     @Override
-    public boolean equals(Object obj) {
+    public boolean equals(@CheckForNull Object obj) {
       if (NativeTypeVariableEquals.NATIVE_TYPE_VARIABLE_ONLY) {
         // equal only to our TypeVariable implementation with identical bounds
         if (obj != null
@@ -482,12 +484,13 @@ public Type[] getLowerBounds() {
     }
 
     @Override
-    public Type[] getUpperBounds() {
+    @SuppressWarnings("value:return")
+    public Type @MinLen(1) [] getUpperBounds() {
       return toArray(upperBounds);
     }
 
     @Override
-    public boolean equals(Object obj) {
+    public boolean equals(@CheckForNull Object obj) {
       if (obj instanceof WildcardType) {
         WildcardType that = (WildcardType) obj;
         return lowerBounds.equals(Arrays.asList(that.getLowerBounds()))
diff --git a/guava/src/com/google/common/util/concurrent/AbstractCatchingFuture.java b/guava/src/com/google/common/util/concurrent/AbstractCatchingFuture.java
index 850e31088f8a..76eada214052 100644
--- a/guava/src/com/google/common/util/concurrent/AbstractCatchingFuture.java
+++ b/guava/src/com/google/common/util/concurrent/AbstractCatchingFuture.java
@@ -17,6 +17,7 @@
 import static com.google.common.base.Preconditions.checkNotNull;
 import static com.google.common.util.concurrent.Futures.getDone;
 import static com.google.common.util.concurrent.MoreExecutors.rejectionPropagatingExecutor;
+import static com.google.common.util.concurrent.NullnessCasts.uncheckedCastNullableTToT;
 import static com.google.common.util.concurrent.Platform.isInstanceOfThrowableClass;
 
 import com.google.common.annotations.GwtCompatible;
@@ -26,13 +27,17 @@
 import com.google.errorprone.annotations.ForOverride;
 import java.util.concurrent.ExecutionException;
 import java.util.concurrent.Executor;
+import javax.annotation.CheckForNull;
 import org.checkerframework.checker.nullness.qual.Nullable;
 
 /** Implementations of {@code Futures.catching*}. */
 @GwtCompatible
-abstract class AbstractCatchingFuture<V, X extends Throwable, F, T>
+@ElementTypesAreNonnullByDefault
+@SuppressWarnings("nullness") // TODO(b/147136275): Remove once our checker understands & and |.
+abstract class AbstractCatchingFuture<
+        V extends @Nullable Object, X extends Throwable, F, T extends @Nullable Object>
     extends FluentFuture.TrustedFuture<V> implements Runnable {
-  static <V, X extends Throwable> ListenableFuture<V> create(
+  static <V extends @Nullable Object, X extends Throwable> ListenableFuture<V> create(
       ListenableFuture<? extends V> input,
       Class<X> exceptionType,
       Function<? super X, ? extends V> fallback,
@@ -42,7 +47,7 @@ static <V, X extends Throwable> ListenableFuture<V> create(
     return future;
   }
 
-  static <X extends Throwable, V> ListenableFuture<V> create(
+  static <X extends Throwable, V extends @Nullable Object> ListenableFuture<V> create(
       ListenableFuture<? extends V> input,
       Class<X> exceptionType,
       AsyncFunction<? super X, ? extends V> fallback,
@@ -56,9 +61,9 @@ static <X extends Throwable, V> ListenableFuture<V> create(
    * In certain circumstances, this field might theoretically not be visible to an afterDone() call
    * triggered by cancel(). For details, see the comments on the fields of TimeoutFuture.
    */
-  @Nullable ListenableFuture<? extends V> inputFuture;
-  @Nullable Class<X> exceptionType;
-  @Nullable F fallback;
+  @CheckForNull ListenableFuture<? extends V> inputFuture;
+  @CheckForNull Class<X> exceptionType;
+  @CheckForNull F fallback;
 
   AbstractCatchingFuture(
       ListenableFuture<? extends V> inputFuture, Class<X> exceptionType, F fallback) {
@@ -107,7 +112,11 @@ public final void run() {
     }
 
     if (throwable == null) {
-      set(sourceResult);
+      /*
+       * The cast is safe: There was no exception, so the assignment from getDone must have
+       * succeeded.
+       */
+      set(uncheckedCastNullableTToT(sourceResult));
       return;
     }
 
@@ -134,6 +143,7 @@ public final void run() {
   }
 
   @Override
+  @CheckForNull
   protected String pendingToString() {
     ListenableFuture<? extends V> localInputFuture = inputFuture;
     Class<X> localExceptionType = exceptionType;
@@ -158,11 +168,12 @@ protected String pendingToString() {
 
   /** Template method for subtypes to actually run the fallback. */
   @ForOverride
-  abstract @Nullable T doFallback(F fallback, X throwable) throws Exception;
+  @ParametricNullness
+  abstract T doFallback(F fallback, X throwable) throws Exception;
 
   /** Template method for subtypes to actually set the result. */
   @ForOverride
-  abstract void setResult(@Nullable T result);
+  abstract void setResult(@ParametricNullness T result);
 
   @Override
   protected final void afterDone() {
@@ -176,7 +187,7 @@ protected final void afterDone() {
    * An {@link AbstractCatchingFuture} that delegates to an {@link AsyncFunction} and {@link
    * #setFuture(ListenableFuture)}.
    */
-  private static final class AsyncCatchingFuture<V, X extends Throwable>
+  private static final class AsyncCatchingFuture<V extends @Nullable Object, X extends Throwable>
       extends AbstractCatchingFuture<
           V, X, AsyncFunction<? super X, ? extends V>, ListenableFuture<? extends V>> {
     AsyncCatchingFuture(
@@ -208,7 +219,7 @@ void setResult(ListenableFuture<? extends V> result) {
    * An {@link AbstractCatchingFuture} that delegates to a {@link Function} and {@link
    * #set(Object)}.
    */
-  private static final class CatchingFuture<V, X extends Throwable>
+  private static final class CatchingFuture<V extends @Nullable Object, X extends Throwable>
       extends AbstractCatchingFuture<V, X, Function<? super X, ? extends V>, V> {
     CatchingFuture(
         ListenableFuture<? extends V> input,
@@ -218,13 +229,13 @@ private static final class CatchingFuture<V, X extends Throwable>
     }
 
     @Override
-    @Nullable
+    @ParametricNullness
     V doFallback(Function<? super X, ? extends V> fallback, X cause) throws Exception {
       return fallback.apply(cause);
     }
 
     @Override
-    void setResult(@Nullable V result) {
+    void setResult(@ParametricNullness V result) {
       set(result);
     }
   }
diff --git a/guava/src/com/google/common/util/concurrent/AbstractExecutionThreadService.java b/guava/src/com/google/common/util/concurrent/AbstractExecutionThreadService.java
index 1bee501ca2be..df5b462d3290 100644
--- a/guava/src/com/google/common/util/concurrent/AbstractExecutionThreadService.java
+++ b/guava/src/com/google/common/util/concurrent/AbstractExecutionThreadService.java
@@ -34,6 +34,7 @@
  * @since 1.0
  */
 @GwtIncompatible
+@ElementTypesAreNonnullByDefault
 public abstract class AbstractExecutionThreadService implements Service {
   private static final Logger logger =
       Logger.getLogger(AbstractExecutionThreadService.class.getName());
diff --git a/guava/src/com/google/common/util/concurrent/AbstractFuture.java b/guava/src/com/google/common/util/concurrent/AbstractFuture.java
index 06feb5a21473..fc408a92d24a 100644
--- a/guava/src/com/google/common/util/concurrent/AbstractFuture.java
+++ b/guava/src/com/google/common/util/concurrent/AbstractFuture.java
@@ -16,8 +16,10 @@
 
 import static com.google.common.base.Preconditions.checkNotNull;
 import static com.google.common.base.Throwables.throwIfUnchecked;
+import static com.google.common.util.concurrent.NullnessCasts.uncheckedNull;
 import static java.lang.Integer.toHexString;
 import static java.lang.System.identityHashCode;
+import static java.util.Objects.requireNonNull;
 import static java.util.concurrent.atomic.AtomicReferenceFieldUpdater.newUpdater;
 
 import com.google.common.annotations.Beta;
@@ -43,6 +45,7 @@
 import java.util.concurrent.locks.LockSupport;
 import java.util.logging.Level;
 import java.util.logging.Logger;
+import javax.annotation.CheckForNull;
 import org.checkerframework.checker.nullness.qual.Nullable;
 
 /**
@@ -64,14 +67,18 @@
  * @author Luke Sandberg
  * @since 1.0
  */
-@SuppressWarnings("ShortCircuitBoolean") // we use non-short circuiting comparisons intentionally
+@SuppressWarnings({
+  "ShortCircuitBoolean", // we use non-short circuiting comparisons intentionally
+  "nullness", // TODO(b/147136275): Remove once our checker understands & and |.
+})
 @GwtCompatible(emulated = true)
 @ReflectionSupport(value = ReflectionSupport.Level.FULL)
-public abstract class AbstractFuture<V> extends InternalFutureFailureAccess
+@ElementTypesAreNonnullByDefault
+public abstract class AbstractFuture<V extends @Nullable Object> extends InternalFutureFailureAccess
     implements ListenableFuture<V> {
   // NOTE: Whenever both tests are cheap and functional, it's faster to use &, | instead of &&, ||
 
-  private static final boolean GENERATE_CANCELLATION_CAUSES;
+  static final boolean GENERATE_CANCELLATION_CAUSES;
 
   static {
     // System.getProperty may throw if the security policy does not permit access.
@@ -91,21 +98,24 @@ public abstract class AbstractFuture<V> extends InternalFutureFailureAccess
    * of this interface must also be an AbstractFuture and must not override or expose for overriding
    * any of the public methods of ListenableFuture.
    */
-  interface Trusted<V> extends ListenableFuture<V> {}
+  interface Trusted<V extends @Nullable Object> extends ListenableFuture<V> {}
 
   /**
    * A less abstract subclass of AbstractFuture. This can be used to optimize setFuture by ensuring
    * that {@link #get} calls exactly the implementation of {@link AbstractFuture#get}.
    */
-  abstract static class TrustedFuture<V> extends AbstractFuture<V> implements Trusted<V> {
+  abstract static class TrustedFuture<V extends @Nullable Object> extends AbstractFuture<V>
+      implements Trusted<V> {
     @CanIgnoreReturnValue
     @Override
+    @ParametricNullness
     public final V get() throws InterruptedException, ExecutionException {
       return super.get();
     }
 
     @CanIgnoreReturnValue
     @Override
+    @ParametricNullness
     public final V get(long timeout, TimeUnit unit)
         throws InterruptedException, ExecutionException, TimeoutException {
       return super.get(timeout, unit);
@@ -191,8 +201,8 @@ public final boolean cancel(boolean mayInterruptIfRunning) {
   private static final class Waiter {
     static final Waiter TOMBSTONE = new Waiter(false /* ignored param */);
 
-    volatile @Nullable Thread thread;
-    volatile @Nullable Waiter next;
+    @CheckForNull volatile Thread thread;
+    @CheckForNull volatile Waiter next;
 
     /**
      * Constructor for the TOMBSTONE, avoids use of ATOMIC_HELPER in case this class is loaded
@@ -207,7 +217,7 @@ private static final class Waiter {
 
     // non-volatile write to the next field. Should be made visible by subsequent CAS on waiters
     // field.
-    void setNext(Waiter next) {
+    void setNext(@CheckForNull Waiter next) {
       ATOMIC_HELPER.putNext(this, next);
     }
 
@@ -264,17 +274,24 @@ private void removeWaiter(Waiter node) {
 
   /** Listeners also form a stack through the {@link #listeners} field. */
   private static final class Listener {
-    static final Listener TOMBSTONE = new Listener(null, null);
+    static final Listener TOMBSTONE = new Listener();
+    @CheckForNull // null only for TOMBSTONE
     final Runnable task;
+    @CheckForNull // null only for TOMBSTONE
     final Executor executor;
 
     // writes to next are made visible by subsequent CAS's on the listeners field
-    @Nullable Listener next;
+    @CheckForNull Listener next;
 
     Listener(Runnable task, Executor executor) {
       this.task = task;
       this.executor = executor;
     }
+
+    Listener() {
+      this.task = null;
+      this.executor = null;
+    }
   }
 
   /** A special value to represent {@code null}. */
@@ -300,8 +317,8 @@ public synchronized Throwable fillInStackTrace() {
   /** A special value to represent cancellation and the 'wasInterrupted' bit. */
   private static final class Cancellation {
     // constants to use when GENERATE_CANCELLATION_CAUSES = false
-    static final Cancellation CAUSELESS_INTERRUPTED;
-    static final Cancellation CAUSELESS_CANCELLED;
+    @CheckForNull static final Cancellation CAUSELESS_INTERRUPTED;
+    @CheckForNull static final Cancellation CAUSELESS_CANCELLED;
 
     static {
       if (GENERATE_CANCELLATION_CAUSES) {
@@ -314,16 +331,16 @@ private static final class Cancellation {
     }
 
     final boolean wasInterrupted;
-    final @Nullable Throwable cause;
+    @CheckForNull final Throwable cause;
 
-    Cancellation(boolean wasInterrupted, @Nullable Throwable cause) {
+    Cancellation(boolean wasInterrupted, @CheckForNull Throwable cause) {
       this.wasInterrupted = wasInterrupted;
       this.cause = cause;
     }
   }
 
   /** A special value that encodes the 'setFuture' state. */
-  private static final class SetFuture<V> implements Runnable {
+  private static final class SetFuture<V extends @Nullable Object> implements Runnable {
     final AbstractFuture<V> owner;
     final ListenableFuture<? extends V> future;
 
@@ -362,13 +379,13 @@ public void run() {
    *       argument.
    * </ul>
    */
-  private volatile @Nullable Object value;
+  @CheckForNull private volatile Object value;
 
   /** All listeners. */
-  private volatile @Nullable Listener listeners;
+  @CheckForNull private volatile Listener listeners;
 
   /** All waiting threads. */
-  private volatile @Nullable Waiter waiters;
+  @CheckForNull private volatile Waiter waiters;
 
   /** Constructor for use by subclasses. */
   protected AbstractFuture() {}
@@ -407,6 +424,7 @@ protected AbstractFuture() {}
    */
   @CanIgnoreReturnValue
   @Override
+  @ParametricNullness
   public V get(long timeout, TimeUnit unit)
       throws InterruptedException, TimeoutException, ExecutionException {
     // NOTE: if timeout < 0, remainingNanos will be < 0 and we will fall into the while(true) loop
@@ -459,7 +477,8 @@ public V get(long timeout, TimeUnit unit)
       }
       // re-read value, if we get here then we must have observed a TOMBSTONE while trying to add a
       // waiter.
-      return getDoneValue(value);
+      // requireNonNull is safe because value is always set before TOMBSTONE.
+      return getDoneValue(requireNonNull(value));
     }
     // If we get here then we have remainingNanos < SPIN_THRESHOLD_NANOS and there is no node on the
     // waiters list
@@ -518,6 +537,7 @@ public V get(long timeout, TimeUnit unit)
    */
   @CanIgnoreReturnValue
   @Override
+  @ParametricNullness
   public V get() throws InterruptedException, ExecutionException {
     if (Thread.interrupted()) {
       throw new InterruptedException();
@@ -553,10 +573,12 @@ public V get() throws InterruptedException, ExecutionException {
     }
     // re-read value, if we get here then we must have observed a TOMBSTONE while trying to add a
     // waiter.
-    return getDoneValue(value);
+    // requireNonNull is safe because value is always set before TOMBSTONE.
+    return getDoneValue(requireNonNull(value));
   }
 
   /** Unboxes {@code obj}. Assumes that obj is not {@code null} or a {@link SetFuture}. */
+  @ParametricNullness
   private V getDoneValue(Object obj) throws ExecutionException {
     // While this seems like it might be too branch-y, simple benchmarking proves it to be
     // unmeasurable (comparing done AbstractFutures with immediateFuture)
@@ -565,7 +587,11 @@ private V getDoneValue(Object obj) throws ExecutionException {
     } else if (obj instanceof Failure) {
       throw new ExecutionException(((Failure) obj).exception);
     } else if (obj == NULL) {
-      return null;
+      /*
+       * It's safe to return null because we would only have stored it in the first place if it were
+       * a valid value for V.
+       */
+      return uncheckedNull();
     } else {
       @SuppressWarnings("unchecked") // this is the only other option
       V asV = (V) obj;
@@ -613,9 +639,20 @@ public boolean cancel(boolean mayInterruptIfRunning) {
           GENERATE_CANCELLATION_CAUSES
               ? new Cancellation(
                   mayInterruptIfRunning, new CancellationException("Future.cancel() was called."))
-              : (mayInterruptIfRunning
-                  ? Cancellation.CAUSELESS_INTERRUPTED
-                  : Cancellation.CAUSELESS_CANCELLED);
+              /*
+               * requireNonNull is safe because we've initialized these if
+               * !GENERATE_CANCELLATION_CAUSES.
+               *
+               * TODO(cpovirk): Maybe it would be cleaner to define a CancellationSupplier interface
+               * with two implementations, one that contains causeless Cancellation instances and
+               * the other of which creates new Cancellation instances each time it's called? Yet
+               * another alternative is to fill in a non-null value for each of the fields no matter
+               * what and to just not use it if !GENERATE_CANCELLATION_CAUSES.
+               */
+              : requireNonNull(
+                  mayInterruptIfRunning
+                      ? Cancellation.CAUSELESS_INTERRUPTED
+                      : Cancellation.CAUSELESS_CANCELLED);
       AbstractFuture<?> abstractFuture = this;
       while (true) {
         if (ATOMIC_HELPER.casValue(abstractFuture, localValue, valueToSet)) {
@@ -740,7 +777,7 @@ public void addListener(Runnable listener, Executor executor) {
    * @return true if the attempt was accepted, completing the {@code Future}
    */
   @CanIgnoreReturnValue
-  protected boolean set(@Nullable V value) {
+  protected boolean set(@ParametricNullness V value) {
     Object valueToSet = value == null ? NULL : value;
     if (ATOMIC_HELPER.casValue(this, null, valueToSet)) {
       complete(this);
@@ -816,7 +853,7 @@ protected boolean setFuture(ListenableFuture<? extends V> future) {
         }
         return false;
       }
-      SetFuture valueToSet = new SetFuture<V>(this, future);
+      SetFuture<V> valueToSet = new SetFuture<V>(this, future);
       if (ATOMIC_HELPER.casValue(this, null, valueToSet)) {
         // the listener is responsible for calling completeWithFuture, directExecutor is appropriate
         // since all we are doing is unpacking a completed future which should be fast.
@@ -873,7 +910,8 @@ private static Object getFutureValue(ListenableFuture<?> future) {
                   : Cancellation.CAUSELESS_CANCELLED;
         }
       }
-      return v;
+      // requireNonNull is safe as long as we call this method only on completed futures.
+      return requireNonNull(v);
     }
     if (future instanceof InternalFutureFailureAccess) {
       Throwable throwable =
@@ -885,7 +923,11 @@ private static Object getFutureValue(ListenableFuture<?> future) {
     boolean wasCancelled = future.isCancelled();
     // Don't allocate a CancellationException if it's not necessary
     if (!GENERATE_CANCELLATION_CAUSES & wasCancelled) {
-      return Cancellation.CAUSELESS_CANCELLED;
+      /*
+       * requireNonNull is safe because we've initialized CAUSELESS_CANCELLED if
+       * !GENERATE_CANCELLATION_CAUSES.
+       */
+      return requireNonNull(Cancellation.CAUSELESS_CANCELLED);
     }
     // Otherwise calculate the value by calling .get()
     try {
@@ -928,7 +970,9 @@ private static Object getFutureValue(ListenableFuture<?> future) {
    * An inlined private copy of {@link Uninterruptibles#getUninterruptibly} used to break an
    * internal dependency on other /util/concurrent classes.
    */
-  private static <V> V getUninterruptibly(Future<V> future) throws ExecutionException {
+  @ParametricNullness
+  private static <V extends @Nullable Object> V getUninterruptibly(Future<V> future)
+      throws ExecutionException {
     boolean interrupted = false;
     try {
       while (true) {
@@ -946,7 +990,10 @@ private static <V> V getUninterruptibly(Future<V> future) throws ExecutionExcept
   }
 
   /** Unblocks all threads and runs all listeners. */
-  private static void complete(AbstractFuture<?> future) {
+  private static void complete(AbstractFuture<?> param) {
+    // Declare a "true" local variable so that the Checker Framework will infer nullness.
+    AbstractFuture<?> future = param;
+
     Listener next = null;
     outer:
     while (true) {
@@ -963,7 +1010,11 @@ private static void complete(AbstractFuture<?> future) {
       while (next != null) {
         Listener curr = next;
         next = next.next;
-        Runnable task = curr.task;
+        /*
+         * requireNonNull is safe because the listener stack never contains TOMBSTONE until after
+         * clearListeners.
+         */
+        Runnable task = requireNonNull(curr.task);
         if (task instanceof SetFuture) {
           SetFuture<?> setFuture = (SetFuture<?>) task;
           // We unwind setFuture specifically to avoid StackOverflowErrors in the case of long
@@ -980,7 +1031,11 @@ private static void complete(AbstractFuture<?> future) {
           }
           // other wise the future we were trying to set is already done.
         } else {
-          executeListener(task, curr.executor);
+          /*
+           * requireNonNull is safe because the listener stack never contains TOMBSTONE until after
+           * clearListeners.
+           */
+          executeListener(task, requireNonNull(curr.executor));
         }
       }
       break;
@@ -1024,7 +1079,13 @@ protected void afterDone() {}
    * @since 27.0
    */
   @Override
-  protected final @Nullable Throwable tryInternalFastPathGetFailure() {
+  /*
+   * We should annotate the superclass, InternalFutureFailureAccess, to say that its copy of this
+   * method returns @Nullable, too. However, we're not sure if we want to make any changes to that
+   * class, since it's in a separate artifact that we planned to release only a single version of.
+   */
+  @CheckForNull
+  protected final Throwable tryInternalFastPathGetFailure() {
     if (this instanceof Trusted) {
       Object obj = value;
       if (obj instanceof Failure) {
@@ -1038,7 +1099,7 @@ protected void afterDone() {}
    * If this future has been cancelled (and possibly interrupted), cancels (and possibly interrupts)
    * the given future (if available).
    */
-  final void maybePropagateCancellationTo(@Nullable Future<?> related) {
+  final void maybePropagateCancellationTo(@CheckForNull Future<?> related) {
     if (related != null & isCancelled()) {
       related.cancel(wasInterrupted());
     }
@@ -1046,10 +1107,7 @@ final void maybePropagateCancellationTo(@Nullable Future<?> related) {
 
   /** Releases all threads in the {@link #waiters} list, and clears the list. */
   private void releaseWaiters() {
-    Waiter head;
-    do {
-      head = waiters;
-    } while (!ATOMIC_HELPER.casWaiters(this, head, Waiter.TOMBSTONE));
+    Waiter head = ATOMIC_HELPER.gasWaiters(this, Waiter.TOMBSTONE);
     for (Waiter currentWaiter = head; currentWaiter != null; currentWaiter = currentWaiter.next) {
       currentWaiter.unpark();
     }
@@ -1059,17 +1117,15 @@ private void releaseWaiters() {
    * Clears the {@link #listeners} list and prepends its contents to {@code onto}, least recently
    * added first.
    */
-  private Listener clearListeners(Listener onto) {
+  @CheckForNull
+  private Listener clearListeners(@CheckForNull Listener onto) {
     // We need to
     // 1. atomically swap the listeners with TOMBSTONE, this is because addListener uses that to
     //    to synchronize with us
     // 2. reverse the linked list, because despite our rather clear contract, people depend on us
     //    executing listeners in the order they were added
     // 3. push all the items onto 'onto' and return the new head of the stack
-    Listener head;
-    do {
-      head = listeners;
-    } while (!ATOMIC_HELPER.casListeners(this, head, Listener.TOMBSTONE));
+    Listener head = ATOMIC_HELPER.gasListeners(this, Listener.TOMBSTONE);
     Listener reversedList = onto;
     while (head != null) {
       Listener tmp = head;
@@ -1107,7 +1163,8 @@ public String toString() {
    * @return null if an explanation cannot be provided (e.g. because the future is done).
    * @since 23.0
    */
-  protected @Nullable String pendingToString() {
+  @CheckForNull
+  protected String pendingToString() {
     // TODO(diamondm) consider moving this into addPendingString so it's always in the output
     if (this instanceof ScheduledFuture) {
       return "remaining delay=["
@@ -1172,7 +1229,7 @@ private void addDoneString(StringBuilder builder) {
    * implementation. Using a reconstruction of the default Object.toString() prevents OOMs and stack
    * overflows, and helps avoid sensitive data inadvertently ending up in exception messages.
    */
-  private void appendResultObject(StringBuilder builder, Object o) {
+  private void appendResultObject(StringBuilder builder, @CheckForNull Object o) {
     if (o == null) {
       builder.append("null");
     } else if (o == this) {
@@ -1186,7 +1243,7 @@ private void appendResultObject(StringBuilder builder, Object o) {
   }
 
   /** Helper for printing user supplied objects into our toString method. */
-  private void appendUserObject(StringBuilder builder, Object o) {
+  private void appendUserObject(StringBuilder builder, @CheckForNull Object o) {
     // This is some basic recursion detection for when people create cycles via set/setFuture or
     // when deep chains of futures exist resulting in a StackOverflowException. We could detect
     // arbitrary cycles using a thread local but this should be a good enough solution (it is also
@@ -1227,16 +1284,24 @@ private abstract static class AtomicHelper {
     abstract void putThread(Waiter waiter, Thread newValue);
 
     /** Non volatile write of the waiter to the {@link Waiter#next} field. */
-    abstract void putNext(Waiter waiter, Waiter newValue);
+    abstract void putNext(Waiter waiter, @CheckForNull Waiter newValue);
 
     /** Performs a CAS operation on the {@link #waiters} field. */
-    abstract boolean casWaiters(AbstractFuture<?> future, Waiter expect, Waiter update);
+    abstract boolean casWaiters(
+        AbstractFuture<?> future, @CheckForNull Waiter expect, @CheckForNull Waiter update);
 
     /** Performs a CAS operation on the {@link #listeners} field. */
-    abstract boolean casListeners(AbstractFuture<?> future, Listener expect, Listener update);
+    abstract boolean casListeners(
+        AbstractFuture<?> future, @CheckForNull Listener expect, Listener update);
+
+    /** Performs a GAS operation on the {@link #waiters} field. */
+    abstract Waiter gasWaiters(AbstractFuture<?> future, Waiter update);
+
+    /** Performs a GAS operation on the {@link #listeners} field. */
+    abstract Listener gasListeners(AbstractFuture<?> future, Listener update);
 
     /** Performs a CAS operation on the {@link #value} field. */
-    abstract boolean casValue(AbstractFuture<?> future, Object expect, Object update);
+    abstract boolean casValue(AbstractFuture<?> future, @CheckForNull Object expect, Object update);
   }
 
   /**
@@ -1245,6 +1310,7 @@ private abstract static class AtomicHelper {
    * <p>Static initialization of this class will fail if the {@link sun.misc.Unsafe} object cannot
    * be accessed.
    */
+  @SuppressWarnings("sunapi")
   private static final class UnsafeAtomicHelper extends AtomicHelper {
     static final sun.misc.Unsafe UNSAFE;
     static final long LISTENERS_OFFSET;
@@ -1299,30 +1365,44 @@ void putThread(Waiter waiter, Thread newValue) {
     }
 
     @Override
-    void putNext(Waiter waiter, Waiter newValue) {
+    void putNext(Waiter waiter, @CheckForNull Waiter newValue) {
       UNSAFE.putObject(waiter, WAITER_NEXT_OFFSET, newValue);
     }
 
     /** Performs a CAS operation on the {@link #waiters} field. */
     @Override
-    boolean casWaiters(AbstractFuture<?> future, Waiter expect, Waiter update) {
+    boolean casWaiters(
+        AbstractFuture<?> future, @CheckForNull Waiter expect, @CheckForNull Waiter update) {
       return UNSAFE.compareAndSwapObject(future, WAITERS_OFFSET, expect, update);
     }
 
     /** Performs a CAS operation on the {@link #listeners} field. */
     @Override
-    boolean casListeners(AbstractFuture<?> future, Listener expect, Listener update) {
+    boolean casListeners(AbstractFuture<?> future, @CheckForNull Listener expect, Listener update) {
       return UNSAFE.compareAndSwapObject(future, LISTENERS_OFFSET, expect, update);
     }
 
+    /** Performs a GAS operation on the {@link #listeners} field. */
+    @Override
+    Listener gasListeners(AbstractFuture<?> future, Listener update) {
+      return (Listener) UNSAFE.getAndSetObject(future, LISTENERS_OFFSET, update);
+    }
+
+    /** Performs a GAS operation on the {@link #waiters} field. */
+    @Override
+    Waiter gasWaiters(AbstractFuture<?> future, Waiter update) {
+      return (Waiter) UNSAFE.getAndSetObject(future, WAITERS_OFFSET, update);
+    }
+
     /** Performs a CAS operation on the {@link #value} field. */
     @Override
-    boolean casValue(AbstractFuture<?> future, Object expect, Object update) {
+    boolean casValue(AbstractFuture<?> future, @CheckForNull Object expect, Object update) {
       return UNSAFE.compareAndSwapObject(future, VALUE_OFFSET, expect, update);
     }
   }
 
   /** {@link AtomicHelper} based on {@link AtomicReferenceFieldUpdater}. */
+  @SuppressWarnings("rawtypes")
   private static final class SafeAtomicHelper extends AtomicHelper {
     final AtomicReferenceFieldUpdater<Waiter, Thread> waiterThreadUpdater;
     final AtomicReferenceFieldUpdater<Waiter, Waiter> waiterNextUpdater;
@@ -1349,22 +1429,35 @@ void putThread(Waiter waiter, Thread newValue) {
     }
 
     @Override
-    void putNext(Waiter waiter, Waiter newValue) {
+    void putNext(Waiter waiter, @CheckForNull Waiter newValue) {
       waiterNextUpdater.lazySet(waiter, newValue);
     }
 
     @Override
-    boolean casWaiters(AbstractFuture<?> future, Waiter expect, Waiter update) {
+    boolean casWaiters(
+        AbstractFuture<?> future, @CheckForNull Waiter expect, @CheckForNull Waiter update) {
       return waitersUpdater.compareAndSet(future, expect, update);
     }
 
     @Override
-    boolean casListeners(AbstractFuture<?> future, Listener expect, Listener update) {
+    boolean casListeners(AbstractFuture<?> future, @CheckForNull Listener expect, Listener update) {
       return listenersUpdater.compareAndSet(future, expect, update);
     }
 
+    /** Performs a GAS operation on the {@link #listeners} field. */
+    @Override
+    Listener gasListeners(AbstractFuture<?> future, Listener update) {
+      return listenersUpdater.getAndSet(future, update);
+    }
+
+    /** Performs a GAS operation on the {@link #waiters} field. */
+    @Override
+    Waiter gasWaiters(AbstractFuture<?> future, Waiter update) {
+      return waitersUpdater.getAndSet(future, update);
+    }
+
     @Override
-    boolean casValue(AbstractFuture<?> future, Object expect, Object update) {
+    boolean casValue(AbstractFuture<?> future, @CheckForNull Object expect, Object update) {
       return valueUpdater.compareAndSet(future, expect, update);
     }
   }
@@ -1382,12 +1475,13 @@ void putThread(Waiter waiter, Thread newValue) {
     }
 
     @Override
-    void putNext(Waiter waiter, Waiter newValue) {
+    void putNext(Waiter waiter, @CheckForNull Waiter newValue) {
       waiter.next = newValue;
     }
 
     @Override
-    boolean casWaiters(AbstractFuture<?> future, Waiter expect, Waiter update) {
+    boolean casWaiters(
+        AbstractFuture<?> future, @CheckForNull Waiter expect, @CheckForNull Waiter update) {
       synchronized (future) {
         if (future.waiters == expect) {
           future.waiters = update;
@@ -1398,7 +1492,7 @@ boolean casWaiters(AbstractFuture<?> future, Waiter expect, Waiter update) {
     }
 
     @Override
-    boolean casListeners(AbstractFuture<?> future, Listener expect, Listener update) {
+    boolean casListeners(AbstractFuture<?> future, @CheckForNull Listener expect, Listener update) {
       synchronized (future) {
         if (future.listeners == expect) {
           future.listeners = update;
@@ -1408,8 +1502,32 @@ boolean casListeners(AbstractFuture<?> future, Listener expect, Listener update)
       }
     }
 
+    /** Performs a GAS operation on the {@link #listeners} field. */
+    @Override
+    Listener gasListeners(AbstractFuture<?> future, Listener update) {
+      synchronized (future) {
+        Listener old = future.listeners;
+        if (old != update) {
+          future.listeners = update;
+        }
+        return old;
+      }
+    }
+
+    /** Performs a GAS operation on the {@link #waiters} field. */
+    @Override
+    Waiter gasWaiters(AbstractFuture<?> future, Waiter update) {
+      synchronized (future) {
+        Waiter old = future.waiters;
+        if (old != update) {
+          future.waiters = update;
+        }
+        return old;
+      }
+    }
+
     @Override
-    boolean casValue(AbstractFuture<?> future, Object expect, Object update) {
+    boolean casValue(AbstractFuture<?> future, @CheckForNull Object expect, Object update) {
       synchronized (future) {
         if (future.value == expect) {
           future.value = update;
@@ -1421,7 +1539,7 @@ boolean casValue(AbstractFuture<?> future, Object expect, Object update) {
   }
 
   private static CancellationException cancellationExceptionWithCause(
-      @Nullable String message, @Nullable Throwable cause) {
+      String message, @CheckForNull Throwable cause) {
     CancellationException exception = new CancellationException(message);
     exception.initCause(cause);
     return exception;
diff --git a/guava/src/com/google/common/util/concurrent/AbstractIdleService.java b/guava/src/com/google/common/util/concurrent/AbstractIdleService.java
index b49db7a3e2fc..fe9faf9e589c 100644
--- a/guava/src/com/google/common/util/concurrent/AbstractIdleService.java
+++ b/guava/src/com/google/common/util/concurrent/AbstractIdleService.java
@@ -32,6 +32,7 @@
  * @since 1.0
  */
 @GwtIncompatible
+@ElementTypesAreNonnullByDefault
 public abstract class AbstractIdleService implements Service {
 
   /* Thread names will look like {@code "MyService STARTING"}. */
diff --git a/guava/src/com/google/common/util/concurrent/AbstractListeningExecutorService.java b/guava/src/com/google/common/util/concurrent/AbstractListeningExecutorService.java
index 960f40e8ffab..fd5c5c911533 100644
--- a/guava/src/com/google/common/util/concurrent/AbstractListeningExecutorService.java
+++ b/guava/src/com/google/common/util/concurrent/AbstractListeningExecutorService.java
@@ -36,18 +36,20 @@
 @Beta
 @CanIgnoreReturnValue
 @GwtIncompatible
+@ElementTypesAreNonnullByDefault
 public abstract class AbstractListeningExecutorService extends AbstractExecutorService
     implements ListeningExecutorService {
 
   /** @since 19.0 (present with return type {@code ListenableFutureTask} since 14.0) */
   @Override
-  protected final <T> RunnableFuture<T> newTaskFor(Runnable runnable, T value) {
+  protected final <T extends @Nullable Object> RunnableFuture<T> newTaskFor(
+      Runnable runnable, @ParametricNullness T value) {
     return TrustedListenableFutureTask.create(runnable, value);
   }
 
   /** @since 19.0 (present with return type {@code ListenableFutureTask} since 14.0) */
   @Override
-  protected final <T> RunnableFuture<T> newTaskFor(Callable<T> callable) {
+  protected final <T extends @Nullable Object> RunnableFuture<T> newTaskFor(Callable<T> callable) {
     return TrustedListenableFutureTask.create(callable);
   }
 
@@ -57,12 +59,13 @@ public ListenableFuture<?> submit(Runnable task) {
   }
 
   @Override
-  public <T> ListenableFuture<T> submit(Runnable task, @Nullable T result) {
+  public <T extends @Nullable Object> ListenableFuture<T> submit(
+      Runnable task, @ParametricNullness T result) {
     return (ListenableFuture<T>) super.submit(task, result);
   }
 
   @Override
-  public <T> ListenableFuture<T> submit(Callable<T> task) {
+  public <T extends @Nullable Object> ListenableFuture<T> submit(Callable<T> task) {
     return (ListenableFuture<T>) super.submit(task);
   }
 }
diff --git a/guava/src/com/google/common/util/concurrent/AbstractScheduledService.java b/guava/src/com/google/common/util/concurrent/AbstractScheduledService.java
index a7a342ad5f6c..db5bf2912101 100644
--- a/guava/src/com/google/common/util/concurrent/AbstractScheduledService.java
+++ b/guava/src/com/google/common/util/concurrent/AbstractScheduledService.java
@@ -16,8 +16,11 @@
 
 import static com.google.common.base.Preconditions.checkArgument;
 import static com.google.common.base.Preconditions.checkNotNull;
+import static com.google.common.util.concurrent.Futures.immediateCancelledFuture;
 import static com.google.common.util.concurrent.Internal.toNanosSaturated;
 import static com.google.common.util.concurrent.MoreExecutors.directExecutor;
+import static java.util.Objects.requireNonNull;
+import static java.util.concurrent.TimeUnit.NANOSECONDS;
 
 import com.google.common.annotations.GwtIncompatible;
 import com.google.common.base.Supplier;
@@ -30,12 +33,14 @@
 import java.util.concurrent.Executors;
 import java.util.concurrent.Future;
 import java.util.concurrent.ScheduledExecutorService;
+import java.util.concurrent.ScheduledFuture;
 import java.util.concurrent.ThreadFactory;
 import java.util.concurrent.TimeUnit;
 import java.util.concurrent.TimeoutException;
 import java.util.concurrent.locks.ReentrantLock;
 import java.util.logging.Level;
 import java.util.logging.Logger;
+import javax.annotation.CheckForNull;
 import org.checkerframework.checker.nullness.qual.Nullable;
 
 /**
@@ -96,6 +101,7 @@
  * @since 11.0
  */
 @GwtIncompatible
+@ElementTypesAreNonnullByDefault
 public abstract class AbstractScheduledService implements Service {
   private static final Logger logger = Logger.getLogger(AbstractScheduledService.class.getName());
 
@@ -123,7 +129,7 @@ public abstract static class Scheduler {
      */
     public static Scheduler newFixedDelaySchedule(Duration initialDelay, Duration delay) {
       return newFixedDelaySchedule(
-          toNanosSaturated(initialDelay), toNanosSaturated(delay), TimeUnit.NANOSECONDS);
+          toNanosSaturated(initialDelay), toNanosSaturated(delay), NANOSECONDS);
     }
 
     /**
@@ -142,9 +148,10 @@ public static Scheduler newFixedDelaySchedule(
       checkArgument(delay > 0, "delay must be > 0, found %s", delay);
       return new Scheduler() {
         @Override
-        public Future<?> schedule(
+        public Cancellable schedule(
             AbstractService service, ScheduledExecutorService executor, Runnable task) {
-          return executor.scheduleWithFixedDelay(task, initialDelay, delay, unit);
+          return new FutureAsCancellable(
+              executor.scheduleWithFixedDelay(task, initialDelay, delay, unit));
         }
       };
     }
@@ -159,7 +166,7 @@ public Future<?> schedule(
      */
     public static Scheduler newFixedRateSchedule(Duration initialDelay, Duration period) {
       return newFixedRateSchedule(
-          toNanosSaturated(initialDelay), toNanosSaturated(period), TimeUnit.NANOSECONDS);
+          toNanosSaturated(initialDelay), toNanosSaturated(period), NANOSECONDS);
     }
 
     /**
@@ -177,15 +184,16 @@ public static Scheduler newFixedRateSchedule(
       checkArgument(period > 0, "period must be > 0, found %s", period);
       return new Scheduler() {
         @Override
-        public Future<?> schedule(
+        public Cancellable schedule(
             AbstractService service, ScheduledExecutorService executor, Runnable task) {
-          return executor.scheduleAtFixedRate(task, initialDelay, period, unit);
+          return new FutureAsCancellable(
+              executor.scheduleAtFixedRate(task, initialDelay, period, unit));
         }
       };
     }
 
     /** Schedules the task to run on the provided executor on behalf of the service. */
-    abstract Future<?> schedule(
+    abstract Cancellable schedule(
         AbstractService service, ScheduledExecutorService executor, Runnable runnable);
 
     private Scheduler() {}
@@ -199,8 +207,8 @@ private final class ServiceDelegate extends AbstractService {
 
     // A handle to the running task so that we can stop it when a shutdown has been requested.
     // These two fields are volatile because their values will be accessed from multiple threads.
-    private volatile @Nullable Future<?> runningTask;
-    private volatile @Nullable ScheduledExecutorService executorService;
+    @CheckForNull private volatile Cancellable runningTask;
+    @CheckForNull private volatile ScheduledExecutorService executorService;
 
     // This lock protects the task so we can ensure that none of the template methods (startUp,
     // shutDown or runOneIteration) run concurrently with one another.
@@ -214,7 +222,11 @@ class Task implements Runnable {
       public void run() {
         lock.lock();
         try {
-          if (runningTask.isCancelled()) {
+          /*
+           * requireNonNull is safe because Task isn't run (or at least it doesn't succeed in taking
+           * the lock) until after it's scheduled and the runningTask field is set.
+           */
+          if (requireNonNull(runningTask).isCancelled()) {
             // task may have been cancelled while blocked on the lock.
             return;
           }
@@ -229,7 +241,8 @@ public void run() {
                 ignored);
           }
           notifyFailed(t);
-          runningTask.cancel(false); // prevent future invocations.
+          // requireNonNull is safe now, just as it was above.
+          requireNonNull(runningTask).cancel(false); // prevent future invocations.
         } finally {
           lock.unlock();
         }
@@ -273,6 +286,9 @@ public void run() {
 
     @Override
     protected final void doStop() {
+      // Both requireNonNull calls are safe because doStop can run only after a successful doStart.
+      requireNonNull(runningTask);
+      requireNonNull(executorService);
       runningTask.cancel(false);
       executorService.execute(
           new Runnable() {
@@ -345,9 +361,9 @@ protected void shutDown() throws Exception {}
    * fails}. Subclasses may override this method to supply a custom {@link ScheduledExecutorService}
    * instance. This method is guaranteed to only be called once.
    *
-   * <p>By default this returns a new {@link ScheduledExecutorService} with a single thread thread
-   * pool that sets the name of the thread to the {@linkplain #serviceName() service name}. Also,
-   * the pool will be {@linkplain ScheduledExecutorService#shutdown() shut down} when the service
+   * <p>By default this returns a new {@link ScheduledExecutorService} with a single thread pool
+   * that sets the name of the thread to the {@linkplain #serviceName() service name}. Also, the
+   * pool will be {@linkplain ScheduledExecutorService#shutdown() shut down} when the service
    * {@linkplain Service.State#TERMINATED terminates} or {@linkplain Service.State#TERMINATED
    * fails}.
    */
@@ -471,6 +487,30 @@ public final void awaitTerminated(long timeout, TimeUnit unit) throws TimeoutExc
     delegate.awaitTerminated(timeout, unit);
   }
 
+  interface Cancellable {
+    void cancel(boolean mayInterruptIfRunning);
+
+    boolean isCancelled();
+  }
+
+  private static final class FutureAsCancellable implements Cancellable {
+    private final Future<?> delegate;
+
+    FutureAsCancellable(Future<?> delegate) {
+      this.delegate = delegate;
+    }
+
+    @Override
+    public void cancel(boolean mayInterruptIfRunning) {
+      delegate.cancel(mayInterruptIfRunning);
+    }
+
+    @Override
+    public boolean isCancelled() {
+      return delegate.isCancelled();
+    }
+  }
+
   /**
    * A {@link Scheduler} that provides a convenient way for the {@link AbstractScheduledService} to
    * use a dynamically changing schedule. After every execution of the task, assuming it hasn't been
@@ -482,7 +522,7 @@ public final void awaitTerminated(long timeout, TimeUnit unit) throws TimeoutExc
   public abstract static class CustomScheduler extends Scheduler {
 
     /** A callable class that can reschedule itself using a {@link CustomScheduler}. */
-    private class ReschedulableCallable extends ForwardingFuture<Void> implements Callable<Void> {
+    private final class ReschedulableCallable implements Callable<@Nullable Void> {
 
       /** The underlying task. */
       private final Runnable wrappedRunnable;
@@ -494,6 +534,27 @@ private class ReschedulableCallable extends ForwardingFuture<Void> implements Ca
        * The service that is managing this callable. This is used so that failure can be reported
        * properly.
        */
+      /*
+       * This reference is part of a reference cycle, which is typically something we want to avoid
+       * under j2objc -- but it is not detected by our j2objc cycle test. The cycle:
+       *
+       * - CustomScheduler.service contains an instance of ServiceDelegate. (It needs it so that it
+       *   can call notifyFailed.)
+       *
+       * - ServiceDelegate.runningTask contains an instance of ReschedulableCallable (at least in
+       *   the case that the service is using CustomScheduler). (It needs it so that it can cancel
+       *   the task and detect whether it has been cancelled.)
+       *
+       * - ReschedulableCallable has a reference back to its enclosing CustomScheduler. (It needs it
+       *   so that it can call getNextSchedule).
+       *
+       * Maybe there is a way to avoid this cycle. But we think the cycle is safe enough to ignore:
+       * Each task is retained for only as long as it is running -- so it's retained only as long as
+       * it would already be retained by the underlying executor.
+       *
+       * If the cycle test starts reporting this cycle in the future, we should add an entry to
+       * cycle_suppress_list.txt.
+       */
       private final AbstractService service;
 
       /**
@@ -505,7 +566,8 @@ private class ReschedulableCallable extends ForwardingFuture<Void> implements Ca
 
       /** The future that represents the next execution of this task. */
       @GuardedBy("lock")
-      private @Nullable Future<Void> currentFuture;
+      @CheckForNull
+      private SupplantableFuture cancellationDelegate;
 
       ReschedulableCallable(
           AbstractService service, ScheduledExecutorService executor, Runnable runnable) {
@@ -515,32 +577,36 @@ private class ReschedulableCallable extends ForwardingFuture<Void> implements Ca
       }
 
       @Override
+      @CheckForNull
       public Void call() throws Exception {
         wrappedRunnable.run();
         reschedule();
         return null;
       }
 
-      /** Atomically reschedules this task and assigns the new future to {@link #currentFuture}. */
-      public void reschedule() {
+      /**
+       * Atomically reschedules this task and assigns the new future to {@link
+       * #cancellationDelegate}.
+       */
+      @CanIgnoreReturnValue
+      public Cancellable reschedule() {
         // invoke the callback outside the lock, prevents some shenanigans.
         Schedule schedule;
         try {
           schedule = CustomScheduler.this.getNextSchedule();
         } catch (Throwable t) {
           service.notifyFailed(t);
-          return;
+          return new FutureAsCancellable(immediateCancelledFuture());
         }
         // We reschedule ourselves with a lock held for two reasons. 1. we want to make sure that
         // cancel calls cancel on the correct future. 2. we want to make sure that the assignment
         // to currentFuture doesn't race with itself so that currentFuture is assigned in the
         // correct order.
         Throwable scheduleFailure = null;
+        Cancellable toReturn;
         lock.lock();
         try {
-          if (currentFuture == null || !currentFuture.isCancelled()) {
-            currentFuture = executor.schedule(this, schedule.delay, schedule.unit);
-          }
+          toReturn = initializeOrUpdateCancellationDelegate(schedule);
         } catch (Throwable e) {
           // If an exception is thrown by the subclass then we need to make sure that the service
           // notices and transitions to the FAILED state. We do it by calling notifyFailed directly
@@ -551,6 +617,7 @@ public void reschedule() {
           // the AbstractService could monitor the future directly. Rescheduling is still hard...
           // but it would help with some of these lock ordering issues.
           scheduleFailure = e;
+          toReturn = new FutureAsCancellable(immediateCancelledFuture());
         } finally {
           lock.unlock();
         }
@@ -558,16 +625,63 @@ public void reschedule() {
         if (scheduleFailure != null) {
           service.notifyFailed(scheduleFailure);
         }
+        return toReturn;
+      }
+
+      @GuardedBy("lock")
+      /*
+       * The GuardedBy checker warns us that we're not holding cancellationDelegate.lock. But in
+       * fact we are holding it because it is the same as this.lock, which we know we are holding,
+       * thanks to @GuardedBy above. (cancellationDelegate.lock is initialized to this.lock in the
+       * call to `new SupplantableFuture` below.)
+       */
+      @SuppressWarnings("GuardedBy")
+      private Cancellable initializeOrUpdateCancellationDelegate(Schedule schedule) {
+        if (cancellationDelegate == null) {
+          return cancellationDelegate = new SupplantableFuture(lock, submitToExecutor(schedule));
+        }
+        if (!cancellationDelegate.currentFuture.isCancelled()) {
+          cancellationDelegate.currentFuture = submitToExecutor(schedule);
+        }
+        return cancellationDelegate;
+      }
+
+      private ScheduledFuture<@Nullable Void> submitToExecutor(Schedule schedule) {
+        return executor.schedule(this, schedule.delay, schedule.unit);
+      }
+    }
+
+    /**
+     * Contains the most recently submitted {@code Future}, which may be cancelled or updated,
+     * always under a lock.
+     */
+    private static final class SupplantableFuture implements Cancellable {
+      private final ReentrantLock lock;
+
+      @GuardedBy("lock")
+      private Future<@Nullable Void> currentFuture;
+
+      SupplantableFuture(ReentrantLock lock, Future<@Nullable Void> currentFuture) {
+        this.lock = lock;
+        this.currentFuture = currentFuture;
       }
 
-      // N.B. Only protect cancel and isCancelled because those are the only methods that are
-      // invoked by the AbstractScheduledService.
       @Override
-      public boolean cancel(boolean mayInterruptIfRunning) {
-        // Ensure that a task cannot be rescheduled while a cancel is ongoing.
+      public void cancel(boolean mayInterruptIfRunning) {
+        /*
+         * Lock to ensure that a task cannot be rescheduled while a cancel is ongoing.
+         *
+         * In theory, cancel() could execute arbitrary listeners -- bad to do while holding a lock.
+         * However, we don't expose currentFuture to users, so they can't attach listeners. And the
+         * Future might not even be a ListenableFuture, just a plain Future. That said, similar
+         * problems can exist with methods like FutureTask.done(), not to mention slow calls to
+         * Thread.interrupt() (as discussed in InterruptibleTask). At the end of the day, it's
+         * unlikely that cancel() will be slow, so we can probably get away with calling it while
+         * holding a lock. Still, it would be nice to avoid somehow.
+         */
         lock.lock();
         try {
-          return currentFuture.cancel(mayInterruptIfRunning);
+          currentFuture.cancel(mayInterruptIfRunning);
         } finally {
           lock.unlock();
         }
@@ -582,20 +696,12 @@ public boolean isCancelled() {
           lock.unlock();
         }
       }
-
-      @Override
-      protected Future<Void> delegate() {
-        throw new UnsupportedOperationException(
-            "Only cancel and isCancelled is supported by this future");
-      }
     }
 
     @Override
-    final Future<?> schedule(
+    final Cancellable schedule(
         AbstractService service, ScheduledExecutorService executor, Runnable runnable) {
-      ReschedulableCallable task = new ReschedulableCallable(service, executor, runnable);
-      task.reschedule();
-      return task;
+      return new ReschedulableCallable(service, executor, runnable).reschedule();
     }
 
     /**
@@ -617,6 +723,14 @@ public Schedule(long delay, TimeUnit unit) {
         this.delay = delay;
         this.unit = checkNotNull(unit);
       }
+
+      /**
+       * @param delay the time from now to delay execution
+       * @since 31.1
+       */
+      public Schedule(Duration delay) {
+        this(toNanosSaturated(delay), NANOSECONDS);
+      }
     }
 
     /**
diff --git a/guava/src/com/google/common/util/concurrent/AbstractService.java b/guava/src/com/google/common/util/concurrent/AbstractService.java
index f5d38edbb616..ae400963c744 100644
--- a/guava/src/com/google/common/util/concurrent/AbstractService.java
+++ b/guava/src/com/google/common/util/concurrent/AbstractService.java
@@ -23,6 +23,7 @@
 import static com.google.common.util.concurrent.Service.State.STARTING;
 import static com.google.common.util.concurrent.Service.State.STOPPING;
 import static com.google.common.util.concurrent.Service.State.TERMINATED;
+import static java.util.Objects.requireNonNull;
 
 import com.google.common.annotations.Beta;
 import com.google.common.annotations.GwtIncompatible;
@@ -36,7 +37,7 @@
 import java.util.concurrent.Executor;
 import java.util.concurrent.TimeUnit;
 import java.util.concurrent.TimeoutException;
-import org.checkerframework.checker.nullness.qual.Nullable;
+import javax.annotation.CheckForNull;
 
 /**
  * Base class for implementing services that can handle {@link #doStart} and {@link #doStop}
@@ -49,6 +50,7 @@
  * @since 1.0
  */
 @GwtIncompatible
+@ElementTypesAreNonnullByDefault
 public abstract class AbstractService implements Service {
   private static final ListenerCallQueue.Event<Listener> STARTING_EVENT =
       new ListenerCallQueue.Event<Listener>() {
@@ -170,7 +172,7 @@ private final class IsStoppedGuard extends Guard {
 
     @Override
     public boolean isSatisfied() {
-      return state().isTerminal();
+      return state().compareTo(TERMINATED) >= 0;
     }
   }
 
@@ -588,20 +590,20 @@ private static final class StateSnapshot {
      * The exception that caused this service to fail. This will be {@code null} unless the service
      * has failed.
      */
-    final @Nullable Throwable failure;
+    @CheckForNull final Throwable failure;
 
     StateSnapshot(State internalState) {
       this(internalState, false, null);
     }
 
     StateSnapshot(
-        State internalState, boolean shutdownWhenStartupFinishes, @Nullable Throwable failure) {
+        State internalState, boolean shutdownWhenStartupFinishes, @CheckForNull Throwable failure) {
       checkArgument(
           !shutdownWhenStartupFinishes || internalState == STARTING,
           "shutdownWhenStartupFinishes can only be set if state is STARTING. Got %s instead.",
           internalState);
       checkArgument(
-          !(failure != null ^ internalState == FAILED),
+          (failure != null) == (internalState == FAILED),
           "A failure cause should be set if and only if the state is failed.  Got %s and %s "
               + "instead.",
           internalState,
@@ -626,7 +628,8 @@ Throwable failureCause() {
           state == FAILED,
           "failureCause() is only valid if the service has failed, service is %s",
           state);
-      return failure;
+      // requireNonNull is safe because the constructor requires a non-null cause with state=FAILED.
+      return requireNonNull(failure);
     }
   }
 }
diff --git a/guava/src/com/google/common/util/concurrent/AbstractTransformFuture.java b/guava/src/com/google/common/util/concurrent/AbstractTransformFuture.java
index e254dc692154..dd68791594ae 100644
--- a/guava/src/com/google/common/util/concurrent/AbstractTransformFuture.java
+++ b/guava/src/com/google/common/util/concurrent/AbstractTransformFuture.java
@@ -24,13 +24,17 @@
 import java.util.concurrent.CancellationException;
 import java.util.concurrent.ExecutionException;
 import java.util.concurrent.Executor;
+import javax.annotation.CheckForNull;
 import org.checkerframework.checker.nullness.qual.Nullable;
 
 /** Implementations of {@code Futures.transform*}. */
 @GwtCompatible
-abstract class AbstractTransformFuture<I, O, F, T> extends FluentFuture.TrustedFuture<O>
-    implements Runnable {
-  static <I, O> ListenableFuture<O> create(
+@ElementTypesAreNonnullByDefault
+@SuppressWarnings("nullness") // TODO(b/147136275): Remove once our checker understands & and |.
+abstract class AbstractTransformFuture<
+        I extends @Nullable Object, O extends @Nullable Object, F, T extends @Nullable Object>
+    extends FluentFuture.TrustedFuture<O> implements Runnable {
+  static <I extends @Nullable Object, O extends @Nullable Object> ListenableFuture<O> create(
       ListenableFuture<I> input,
       AsyncFunction<? super I, ? extends O> function,
       Executor executor) {
@@ -40,7 +44,7 @@ static <I, O> ListenableFuture<O> create(
     return output;
   }
 
-  static <I, O> ListenableFuture<O> create(
+  static <I extends @Nullable Object, O extends @Nullable Object> ListenableFuture<O> create(
       ListenableFuture<I> input, Function<? super I, ? extends O> function, Executor executor) {
     checkNotNull(function);
     TransformFuture<I, O> output = new TransformFuture<>(input, function);
@@ -52,8 +56,8 @@ static <I, O> ListenableFuture<O> create(
    * In certain circumstances, this field might theoretically not be visible to an afterDone() call
    * triggered by cancel(). For details, see the comments on the fields of TimeoutFuture.
    */
-  @Nullable ListenableFuture<? extends I> inputFuture;
-  @Nullable F function;
+  @CheckForNull ListenableFuture<? extends I> inputFuture;
+  @CheckForNull F function;
 
   AbstractTransformFuture(ListenableFuture<? extends I> inputFuture, F function) {
     this.inputFuture = checkNotNull(inputFuture);
@@ -165,11 +169,12 @@ public final void run() {
 
   /** Template method for subtypes to actually run the transform. */
   @ForOverride
-  abstract @Nullable T doTransform(F function, @Nullable I result) throws Exception;
+  @ParametricNullness
+  abstract T doTransform(F function, @ParametricNullness I result) throws Exception;
 
   /** Template method for subtypes to actually set the result. */
   @ForOverride
-  abstract void setResult(@Nullable T result);
+  abstract void setResult(@ParametricNullness T result);
 
   @Override
   protected final void afterDone() {
@@ -179,6 +184,7 @@ protected final void afterDone() {
   }
 
   @Override
+  @CheckForNull
   protected String pendingToString() {
     ListenableFuture<? extends I> localInputFuture = inputFuture;
     F localFunction = function;
@@ -199,7 +205,8 @@ protected String pendingToString() {
    * An {@link AbstractTransformFuture} that delegates to an {@link AsyncFunction} and {@link
    * #setFuture(ListenableFuture)}.
    */
-  private static final class AsyncTransformFuture<I, O>
+  private static final class AsyncTransformFuture<
+          I extends @Nullable Object, O extends @Nullable Object>
       extends AbstractTransformFuture<
           I, O, AsyncFunction<? super I, ? extends O>, ListenableFuture<? extends O>> {
     AsyncTransformFuture(
@@ -209,7 +216,8 @@ private static final class AsyncTransformFuture<I, O>
 
     @Override
     ListenableFuture<? extends O> doTransform(
-        AsyncFunction<? super I, ? extends O> function, @Nullable I input) throws Exception {
+        AsyncFunction<? super I, ? extends O> function, @ParametricNullness I input)
+        throws Exception {
       ListenableFuture<? extends O> outputFuture = function.apply(input);
       checkNotNull(
           outputFuture,
@@ -229,7 +237,7 @@ void setResult(ListenableFuture<? extends O> result) {
    * An {@link AbstractTransformFuture} that delegates to a {@link Function} and {@link
    * #set(Object)}.
    */
-  private static final class TransformFuture<I, O>
+  private static final class TransformFuture<I extends @Nullable Object, O extends @Nullable Object>
       extends AbstractTransformFuture<I, O, Function<? super I, ? extends O>, O> {
     TransformFuture(
         ListenableFuture<? extends I> inputFuture, Function<? super I, ? extends O> function) {
@@ -237,13 +245,13 @@ private static final class TransformFuture<I, O>
     }
 
     @Override
-    @Nullable
-    O doTransform(Function<? super I, ? extends O> function, @Nullable I input) {
+    @ParametricNullness
+    O doTransform(Function<? super I, ? extends O> function, @ParametricNullness I input) {
       return function.apply(input);
     }
 
     @Override
-    void setResult(@Nullable O result) {
+    void setResult(@ParametricNullness O result) {
       set(result);
     }
   }
diff --git a/guava/src/com/google/common/util/concurrent/AggregateFuture.java b/guava/src/com/google/common/util/concurrent/AggregateFuture.java
index 3104da3748e6..6d2ed9c8e8cd 100644
--- a/guava/src/com/google/common/util/concurrent/AggregateFuture.java
+++ b/guava/src/com/google/common/util/concurrent/AggregateFuture.java
@@ -20,6 +20,7 @@
 import static com.google.common.util.concurrent.AggregateFuture.ReleaseResourcesReason.OUTPUT_FUTURE_DONE;
 import static com.google.common.util.concurrent.Futures.getDone;
 import static com.google.common.util.concurrent.MoreExecutors.directExecutor;
+import static java.util.Objects.requireNonNull;
 import static java.util.logging.Level.SEVERE;
 
 import com.google.common.annotations.GwtCompatible;
@@ -30,6 +31,7 @@
 import java.util.concurrent.ExecutionException;
 import java.util.concurrent.Future;
 import java.util.logging.Logger;
+import javax.annotation.CheckForNull;
 import org.checkerframework.checker.nullness.qual.Nullable;
 
 /**
@@ -39,7 +41,9 @@
  * @param <OutputT> the type of the output (i.e. this) future
  */
 @GwtCompatible
-abstract class AggregateFuture<InputT, OutputT> extends AggregateFutureState<OutputT> {
+@ElementTypesAreNonnullByDefault
+abstract class AggregateFuture<InputT extends @Nullable Object, OutputT extends @Nullable Object>
+    extends AggregateFutureState<OutputT> {
   private static final Logger logger = Logger.getLogger(AggregateFuture.class.getName());
 
   /**
@@ -52,7 +56,7 @@ abstract class AggregateFuture<InputT, OutputT> extends AggregateFutureState<Out
    * In certain circumstances, this field might theoretically not be visible to an afterDone() call
    * triggered by cancel(). For details, see the comments on the fields of TimeoutFuture.
    */
-  private @Nullable ImmutableCollection<? extends ListenableFuture<? extends InputT>> futures;
+  @CheckForNull private ImmutableCollection<? extends ListenableFuture<? extends InputT>> futures;
 
   private final boolean allMustSucceed;
   private final boolean collectsValues;
@@ -87,6 +91,7 @@ protected final void afterDone() {
   }
 
   @Override
+  @CheckForNull
   protected final String pendingToString() {
     ImmutableCollection<? extends Future<?>> localFutures = futures;
     if (localFutures != null) {
@@ -103,6 +108,13 @@ protected final String pendingToString() {
    * we're guaranteed to have properly initialized the subclass.
    */
   final void init() {
+    /*
+     * requireNonNull is safe because this is called from the constructor after `futures` is set but
+     * before releaseResources could be called (because we have not yet set up any of the listeners
+     * that could call it, nor exposed this Future for users to call cancel() on).
+     */
+    requireNonNull(futures);
+
     // Corner case: List is empty.
     if (futures.isEmpty()) {
       handleAllCompleted();
@@ -123,29 +135,26 @@ final void init() {
       // This is not actually a problem, since the foreach only needs this.futures to be non-null
       // at the beginning of the loop.
       int i = 0;
-      for (final ListenableFuture<? extends InputT> future : futures) {
-        final int index = i++;
+      for (ListenableFuture<? extends InputT> future : futures) {
+        int index = i++;
         future.addListener(
-            new Runnable() {
-              @Override
-              public void run() {
-                try {
-                  if (future.isCancelled()) {
-                    // Clear futures prior to cancelling children. This sets our own state but lets
-                    // the input futures keep running, as some of them may be used elsewhere.
-                    futures = null;
-                    cancel(false);
-                  } else {
-                    collectValueFromNonCancelledFuture(index, future);
-                  }
-                } finally {
-                  /*
-                   * "null" means: There is no need to access `futures` again during
-                   * `processCompleted` because we're reading each value during a call to
-                   * handleOneInputDone.
-                   */
-                  decrementCountAndMaybeComplete(null);
+            () -> {
+              try {
+                if (future.isCancelled()) {
+                  // Clear futures prior to cancelling children. This sets our own state but lets
+                  // the input futures keep running, as some of them may be used elsewhere.
+                  futures = null;
+                  cancel(false);
+                } else {
+                  collectValueFromNonCancelledFuture(index, future);
                 }
+              } finally {
+                /*
+                 * "null" means: There is no need to access `futures` again during
+                 * `processCompleted` because we're reading each value during a call to
+                 * handleOneInputDone.
+                 */
+                decrementCountAndMaybeComplete(null);
               }
             },
             directExecutor());
@@ -167,15 +176,9 @@ public void run() {
        * could actually hurt in some cases, as it forces us to keep all inputs in memory until the
        * final input completes.
        */
-      final ImmutableCollection<? extends Future<? extends InputT>> localFutures =
+      ImmutableCollection<? extends Future<? extends InputT>> localFutures =
           collectsValues ? futures : null;
-      Runnable listener =
-          new Runnable() {
-            @Override
-            public void run() {
-              decrementCountAndMaybeComplete(localFutures);
-            }
-          };
+      Runnable listener = () -> decrementCountAndMaybeComplete(localFutures);
       for (ListenableFuture<? extends InputT> future : futures) {
         future.addListener(listener, directExecutor());
       }
@@ -222,12 +225,11 @@ private void handleException(Throwable throwable) {
     }
   }
 
-  private void log(Throwable throwable) {
+  private static void log(Throwable throwable) {
     String message =
         (throwable instanceof Error)
             ? "Input Future failed with Error"
-            : "An additional input failed after the first. Logging it after adding the first"
-                + " failure as a suppressed exception.";
+            : "Got more than one input Future failure. Logging failures after the first";
     logger.log(SEVERE, message, throwable);
   }
 
@@ -235,8 +237,24 @@ private void log(Throwable throwable) {
   final void addInitialException(Set<Throwable> seen) {
     checkNotNull(seen);
     if (!isCancelled()) {
-      // TODO(cpovirk): Think about whether we could/should use Verify to check this.
-      boolean unused = addCausalChain(seen, tryInternalFastPathGetFailure());
+      /*
+       * requireNonNull is safe because:
+       *
+       * - This is a TrustedFuture, so tryInternalFastPathGetFailure will in fact return the failure
+       *   cause if this Future has failed.
+       *
+       * - And this future *has* failed: This method is called only from handleException (through
+       *   getOrInitSeenExceptions). handleException tried to call setException and failed, so
+       *   either this Future was cancelled (which we ruled out with the isCancelled check above),
+       *   or it had already failed. (It couldn't have completed *successfully* or even had
+       *   setFuture called on it: Neither of those can happen until we've finished processing all
+       *   the completed inputs. And we're still processing at least one input, the one that
+       *   triggered handleException.)
+       *
+       * TODO(cpovirk): Think about whether we could/should use Verify to check the return value of
+       * addCausalChain.
+       */
+      boolean unused = addCausalChain(seen, requireNonNull(tryInternalFastPathGetFailure()));
     }
   }
 
@@ -256,7 +274,7 @@ private void collectValueFromNonCancelledFuture(int index, Future<? extends Inpu
   }
 
   private void decrementCountAndMaybeComplete(
-      @Nullable
+      @CheckForNull
           ImmutableCollection<? extends Future<? extends InputT>>
               futuresIfNeedToCollectAtCompletion) {
     int newRemaining = decrementRemainingAndGet();
@@ -267,7 +285,7 @@ private void decrementCountAndMaybeComplete(
   }
 
   private void processCompleted(
-      @Nullable
+      @CheckForNull
           ImmutableCollection<? extends Future<? extends InputT>>
               futuresIfNeedToCollectAtCompletion) {
     if (futuresIfNeedToCollectAtCompletion != null) {
@@ -323,12 +341,15 @@ enum ReleaseResourcesReason {
    * If {@code allMustSucceed} is true, called as each future completes; otherwise, if {@code
    * collectsValues} is true, called for each future when all futures complete.
    */
-  abstract void collectOneValue(int index, @Nullable InputT returnValue);
+  abstract void collectOneValue(int index, @ParametricNullness InputT returnValue);
 
   abstract void handleAllCompleted();
 
   /** Adds the chain to the seen set, and returns whether all the chain was new to us. */
-  private static boolean addCausalChain(Set<Throwable> seen, Throwable t) {
+  private static boolean addCausalChain(Set<Throwable> seen, Throwable param) {
+    // Declare a "true" local variable so that the Checker Framework will infer nullness.
+    Throwable t = param;
+
     for (; t != null; t = t.getCause()) {
       boolean firstTimeSeen = seen.add(t);
       if (!firstTimeSeen) {
diff --git a/guava/src/com/google/common/util/concurrent/AggregateFutureState.java b/guava/src/com/google/common/util/concurrent/AggregateFutureState.java
index f8398d817eb2..ee23ca021e97 100644
--- a/guava/src/com/google/common/util/concurrent/AggregateFutureState.java
+++ b/guava/src/com/google/common/util/concurrent/AggregateFutureState.java
@@ -15,6 +15,7 @@
 package com.google.common.util.concurrent;
 
 import static com.google.common.collect.Sets.newConcurrentHashSet;
+import static java.util.Objects.requireNonNull;
 import static java.util.concurrent.atomic.AtomicIntegerFieldUpdater.newUpdater;
 import static java.util.concurrent.atomic.AtomicReferenceFieldUpdater.newUpdater;
 
@@ -25,6 +26,8 @@
 import java.util.concurrent.atomic.AtomicReferenceFieldUpdater;
 import java.util.logging.Level;
 import java.util.logging.Logger;
+import javax.annotation.CheckForNull;
+import org.checkerframework.checker.nullness.qual.Nullable;
 
 /**
  * A helper which does some thread-safe operations for aggregate futures, which must be implemented
@@ -37,10 +40,12 @@
  */
 @GwtCompatible(emulated = true)
 @ReflectionSupport(value = ReflectionSupport.Level.FULL)
-abstract class AggregateFutureState<OutputT> extends AbstractFuture.TrustedFuture<OutputT> {
+@ElementTypesAreNonnullByDefault
+abstract class AggregateFutureState<OutputT extends @Nullable Object>
+    extends AbstractFuture.TrustedFuture<OutputT> {
   // Lazily initialized the first time we see an exception; not released until all the input futures
   // have completed and we have processed them all.
-  private volatile Set<Throwable> seenExceptions = null;
+  @CheckForNull private volatile Set<Throwable> seenExceptions = null;
 
   private volatile int remaining;
 
@@ -54,7 +59,7 @@ abstract class AggregateFutureState<OutputT> extends AbstractFuture.TrustedFutur
     try {
       helper =
           new SafeAtomicHelper(
-              newUpdater(AggregateFutureState.class, (Class) Set.class, "seenExceptions"),
+              newUpdater(AggregateFutureState.class, Set.class, "seenExceptions"),
               newUpdater(AggregateFutureState.class, "remaining"));
     } catch (Throwable reflectionFailure) {
       // Some Android 5.0.x Samsung devices have bugs in JDK reflection APIs that cause
@@ -124,8 +129,11 @@ final Set<Throwable> getOrInitSeenExceptions() {
        * other callers have added to it.
        *
        * This read is guaranteed to get us the right value because we only set this once (here).
+       *
+       * requireNonNull is safe because either our compareAndSet succeeded or it failed because
+       * another thread did it for us.
        */
-      seenExceptionsLocal = seenExceptions;
+      seenExceptionsLocal = requireNonNull(seenExceptions);
     }
     return seenExceptionsLocal;
   }
@@ -144,32 +152,37 @@ final void clearSeenExceptions() {
   private abstract static class AtomicHelper {
     /** Atomic compare-and-set of the {@link AggregateFutureState#seenExceptions} field. */
     abstract void compareAndSetSeenExceptions(
-        AggregateFutureState state, Set<Throwable> expect, Set<Throwable> update);
+        AggregateFutureState<?> state, @CheckForNull Set<Throwable> expect, Set<Throwable> update);
 
     /** Atomic decrement-and-get of the {@link AggregateFutureState#remaining} field. */
-    abstract int decrementAndGetRemainingCount(AggregateFutureState state);
+    abstract int decrementAndGetRemainingCount(AggregateFutureState<?> state);
   }
 
   private static final class SafeAtomicHelper extends AtomicHelper {
-    final AtomicReferenceFieldUpdater<AggregateFutureState, Set<Throwable>> seenExceptionsUpdater;
+    final AtomicReferenceFieldUpdater<AggregateFutureState<?>, Set<Throwable>>
+        seenExceptionsUpdater;
 
-    final AtomicIntegerFieldUpdater<AggregateFutureState> remainingCountUpdater;
+    final AtomicIntegerFieldUpdater<AggregateFutureState<?>> remainingCountUpdater;
 
+    @SuppressWarnings({"rawtypes", "unchecked"}) // Unavoidable with reflection API
     SafeAtomicHelper(
         AtomicReferenceFieldUpdater seenExceptionsUpdater,
         AtomicIntegerFieldUpdater remainingCountUpdater) {
-      this.seenExceptionsUpdater = seenExceptionsUpdater;
-      this.remainingCountUpdater = remainingCountUpdater;
+      this.seenExceptionsUpdater =
+          (AtomicReferenceFieldUpdater<AggregateFutureState<?>, Set<Throwable>>)
+              seenExceptionsUpdater;
+      this.remainingCountUpdater =
+          (AtomicIntegerFieldUpdater<AggregateFutureState<?>>) remainingCountUpdater;
     }
 
     @Override
     void compareAndSetSeenExceptions(
-        AggregateFutureState state, Set<Throwable> expect, Set<Throwable> update) {
+        AggregateFutureState<?> state, @CheckForNull Set<Throwable> expect, Set<Throwable> update) {
       seenExceptionsUpdater.compareAndSet(state, expect, update);
     }
 
     @Override
-    int decrementAndGetRemainingCount(AggregateFutureState state) {
+    int decrementAndGetRemainingCount(AggregateFutureState<?> state) {
       return remainingCountUpdater.decrementAndGet(state);
     }
   }
@@ -177,7 +190,7 @@ int decrementAndGetRemainingCount(AggregateFutureState state) {
   private static final class SynchronizedAtomicHelper extends AtomicHelper {
     @Override
     void compareAndSetSeenExceptions(
-        AggregateFutureState state, Set<Throwable> expect, Set<Throwable> update) {
+        AggregateFutureState<?> state, @CheckForNull Set<Throwable> expect, Set<Throwable> update) {
       synchronized (state) {
         if (state.seenExceptions == expect) {
           state.seenExceptions = update;
@@ -186,7 +199,7 @@ void compareAndSetSeenExceptions(
     }
 
     @Override
-    int decrementAndGetRemainingCount(AggregateFutureState state) {
+    int decrementAndGetRemainingCount(AggregateFutureState<?> state) {
       synchronized (state) {
         return --state.remaining;
       }
diff --git a/guava/src/com/google/common/util/concurrent/AsyncCallable.java b/guava/src/com/google/common/util/concurrent/AsyncCallable.java
index f39a88260d57..c3cbb78a9fae 100644
--- a/guava/src/com/google/common/util/concurrent/AsyncCallable.java
+++ b/guava/src/com/google/common/util/concurrent/AsyncCallable.java
@@ -14,9 +14,9 @@
 
 package com.google.common.util.concurrent;
 
-import com.google.common.annotations.Beta;
 import com.google.common.annotations.GwtCompatible;
 import java.util.concurrent.Future;
+import org.checkerframework.checker.nullness.qual.Nullable;
 
 /**
  * Computes a value, possibly asynchronously. For an example usage and more information, see {@link
@@ -27,10 +27,10 @@
  *
  * @since 20.0
  */
-@Beta
 @FunctionalInterface
 @GwtCompatible
-public interface AsyncCallable<V> {
+@ElementTypesAreNonnullByDefault
+public interface AsyncCallable<V extends @Nullable Object> {
   /**
    * Computes a result {@code Future}. The output {@code Future} need not be {@linkplain
    * Future#isDone done}, making {@code AsyncCallable} suitable for asynchronous derivations.
diff --git a/guava/src/com/google/common/util/concurrent/AsyncFunction.java b/guava/src/com/google/common/util/concurrent/AsyncFunction.java
index bae9bce3a021..3a19db4a5e20 100644
--- a/guava/src/com/google/common/util/concurrent/AsyncFunction.java
+++ b/guava/src/com/google/common/util/concurrent/AsyncFunction.java
@@ -27,7 +27,8 @@
  */
 @GwtCompatible
 @FunctionalInterface
-public interface AsyncFunction<I, O> {
+@ElementTypesAreNonnullByDefault
+public interface AsyncFunction<I extends @Nullable Object, O extends @Nullable Object> {
   /**
    * Returns an output {@code Future} to use in place of the given {@code input}. The output {@code
    * Future} need not be {@linkplain Future#isDone done}, making {@code AsyncFunction} suitable for
@@ -35,5 +36,5 @@ public interface AsyncFunction<I, O> {
    *
    * <p>Throwing an exception from this method is equivalent to returning a failing {@code Future}.
    */
-  ListenableFuture<O> apply(@Nullable I input) throws Exception;
+  ListenableFuture<O> apply(@ParametricNullness I input) throws Exception;
 }
diff --git a/guava/src/com/google/common/util/concurrent/AtomicDouble.java b/guava/src/com/google/common/util/concurrent/AtomicDouble.java
index e57bdc7b95f4..cdd63a8b86b9 100644
--- a/guava/src/com/google/common/util/concurrent/AtomicDouble.java
+++ b/guava/src/com/google/common/util/concurrent/AtomicDouble.java
@@ -14,6 +14,7 @@
 
 package com.google.common.util.concurrent;
 
+import static com.google.common.base.Preconditions.checkNotNull;
 import static java.lang.Double.doubleToRawLongBits;
 import static java.lang.Double.longBitsToDouble;
 
@@ -21,6 +22,8 @@
 import com.google.errorprone.annotations.CanIgnoreReturnValue;
 import com.google.j2objc.annotations.ReflectionSupport;
 import java.util.concurrent.atomic.AtomicLongFieldUpdater;
+import java.util.function.DoubleBinaryOperator;
+import java.util.function.DoubleUnaryOperator;
 
 import org.checkerframework.common.value.qual.PolyValue;
 
@@ -55,6 +58,7 @@
  */
 @GwtIncompatible
 @ReflectionSupport(value = ReflectionSupport.Level.FULL)
+@ElementTypesAreNonnullByDefault
 public class AtomicDouble extends Number implements java.io.Serializable {
   private static final long serialVersionUID = 0L;
 
@@ -156,10 +160,63 @@ public final boolean weakCompareAndSet(double expect, double update) {
    */
   @CanIgnoreReturnValue
   public final double getAndAdd(double delta) {
+    return getAndAccumulate(delta, Double::sum);
+  }
+
+  /**
+   * Atomically adds the given value to the current value.
+   *
+   * @param delta the value to add
+   * @return the updated value
+   */
+  @CanIgnoreReturnValue
+  public final double addAndGet(double delta) {
+    return accumulateAndGet(delta, Double::sum);
+  }
+
+  /**
+   * Atomically updates the current value with the results of applying the given function to the
+   * current and given values.
+   *
+   * @param x the update value
+   * @param accumulatorFunction the accumulator function
+   * @return the previous value
+   * @since 31.1
+   */
+  @CanIgnoreReturnValue
+  public final double getAndAccumulate(double x, DoubleBinaryOperator accumulatorFunction) {
+    checkNotNull(accumulatorFunction);
+    return getAndUpdate(oldValue -> accumulatorFunction.applyAsDouble(oldValue, x));
+  }
+
+  /**
+   * Atomically updates the current value with the results of applying the given function to the
+   * current and given values.
+   *
+   * @param x the update value
+   * @param accumulatorFunction the accumulator function
+   * @return the updated value
+   * @since 31.1
+   */
+  @CanIgnoreReturnValue
+  public final double accumulateAndGet(double x, DoubleBinaryOperator accumulatorFunction) {
+    checkNotNull(accumulatorFunction);
+    return updateAndGet(oldValue -> accumulatorFunction.applyAsDouble(oldValue, x));
+  }
+
+  /**
+   * Atomically updates the current value with the results of applying the given function.
+   *
+   * @param updateFunction the update function
+   * @return the previous value
+   * @since 31.1
+   */
+  @CanIgnoreReturnValue
+  public final double getAndUpdate(DoubleUnaryOperator updateFunction) {
     while (true) {
       long current = value;
       double currentVal = longBitsToDouble(current);
-      double nextVal = currentVal + delta;
+      double nextVal = updateFunction.applyAsDouble(currentVal);
       long next = doubleToRawLongBits(nextVal);
       if (updater.compareAndSet(this, current, next)) {
         return currentVal;
@@ -168,17 +225,18 @@ public final double getAndAdd(double delta) {
   }
 
   /**
-   * Atomically adds the given value to the current value.
+   * Atomically updates the current value with the results of applying the given function.
    *
-   * @param delta the value to add
+   * @param updateFunction the update function
    * @return the updated value
+   * @since 31.1
    */
   @CanIgnoreReturnValue
-  public final double addAndGet(double delta) {
+  public final double updateAndGet(DoubleUnaryOperator updateFunction) {
     while (true) {
       long current = value;
       double currentVal = longBitsToDouble(current);
-      double nextVal = currentVal + delta;
+      double nextVal = updateFunction.applyAsDouble(currentVal);
       long next = doubleToRawLongBits(nextVal);
       if (updater.compareAndSet(this, current, next)) {
         return nextVal;
diff --git a/guava/src/com/google/common/util/concurrent/AtomicDoubleArray.java b/guava/src/com/google/common/util/concurrent/AtomicDoubleArray.java
index 5c4baa163aab..6cc28aad0ab4 100644
--- a/guava/src/com/google/common/util/concurrent/AtomicDoubleArray.java
+++ b/guava/src/com/google/common/util/concurrent/AtomicDoubleArray.java
@@ -13,6 +13,7 @@
 
 package com.google.common.util.concurrent;
 
+import static com.google.common.base.Preconditions.checkNotNull;
 import static java.lang.Double.doubleToRawLongBits;
 import static java.lang.Double.longBitsToDouble;
 
@@ -20,6 +21,8 @@
 import com.google.common.primitives.ImmutableLongArray;
 import com.google.errorprone.annotations.CanIgnoreReturnValue;
 import java.util.concurrent.atomic.AtomicLongArray;
+import java.util.function.DoubleBinaryOperator;
+import java.util.function.DoubleUnaryOperator;
 
 /**
  * A {@code double} array in which elements may be updated atomically. See the {@link
@@ -44,6 +47,7 @@
  * @since 11.0
  */
 @GwtIncompatible
+@ElementTypesAreNonnullByDefault
 public class AtomicDoubleArray implements java.io.Serializable {
   private static final long serialVersionUID = 0L;
 
@@ -68,7 +72,7 @@ public AtomicDoubleArray(int length) {
    * @throws NullPointerException if array is null
    */
   public AtomicDoubleArray(double[] array) {
-    final int len = array.length;
+    int len = array.length;
     long[] longArray = new long[len];
     for (int i = 0; i < len; i++) {
       longArray[i] = doubleToRawLongBits(array[i]);
@@ -96,7 +100,7 @@ public final double get(int i) {
   }
 
   /**
-   * Sets the element at position {@code i} to the given value.
+   * Atomically sets the element at position {@code i} to the given value.
    *
    * @param i the index
    * @param newValue the new value
@@ -170,10 +174,68 @@ public final boolean weakCompareAndSet(int i, double expect, double update) {
    */
   @CanIgnoreReturnValue
   public final double getAndAdd(int i, double delta) {
+    return getAndAccumulate(i, delta, Double::sum);
+  }
+
+  /**
+   * Atomically adds the given value to the element at index {@code i}.
+   *
+   * @param i the index
+   * @param delta the value to add
+   * @return the updated value
+   */
+  @CanIgnoreReturnValue
+  public double addAndGet(int i, double delta) {
+    return accumulateAndGet(i, delta, Double::sum);
+  }
+
+  /**
+   * Atomically updates the element at index {@code i} with the results of applying the given
+   * function to the curernt and given values.
+   *
+   * @param i the index to update
+   * @param x the update value
+   * @param accumulatorFunction the accumulator function
+   * @return the previous value
+   * @since 31.1
+   */
+  @CanIgnoreReturnValue
+  public final double getAndAccumulate(int i, double x, DoubleBinaryOperator accumulatorFunction) {
+    checkNotNull(accumulatorFunction);
+    return getAndUpdate(i, oldValue -> accumulatorFunction.applyAsDouble(oldValue, x));
+  }
+
+  /**
+   * Atomically updates the element at index {@code i} with the results of applying the given
+   * function to the curernt and given values.
+   *
+   * @param i the index to update
+   * @param x the update value
+   * @param accumulatorFunction the accumulator function
+   * @return the updated value
+   * @since 31.1
+   */
+  @CanIgnoreReturnValue
+  public final double accumulateAndGet(int i, double x, DoubleBinaryOperator accumulatorFunction) {
+    checkNotNull(accumulatorFunction);
+    return updateAndGet(i, oldValue -> accumulatorFunction.applyAsDouble(oldValue, x));
+  }
+
+  /**
+   * Atomically updates the element at index {@code i} with the results of applying the given
+   * function to the curernt value.
+   *
+   * @param i the index to update
+   * @param updaterFunction the update function
+   * @return the previous value
+   * @since 31.1
+   */
+  @CanIgnoreReturnValue
+  public final double getAndUpdate(int i, DoubleUnaryOperator updaterFunction) {
     while (true) {
       long current = longs.get(i);
       double currentVal = longBitsToDouble(current);
-      double nextVal = currentVal + delta;
+      double nextVal = updaterFunction.applyAsDouble(currentVal);
       long next = doubleToRawLongBits(nextVal);
       if (longs.compareAndSet(i, current, next)) {
         return currentVal;
@@ -182,18 +244,20 @@ public final double getAndAdd(int i, double delta) {
   }
 
   /**
-   * Atomically adds the given value to the element at index {@code i}.
+   * Atomically updates the element at index {@code i} with the results of applying the given
+   * function to the curernt value.
    *
-   * @param i the index
-   * @param delta the value to add
+   * @param i the index to update
+   * @param updaterFunction the update function
    * @return the updated value
+   * @since 31.1
    */
   @CanIgnoreReturnValue
-  public double addAndGet(int i, double delta) {
+  public final double updateAndGet(int i, DoubleUnaryOperator updaterFunction) {
     while (true) {
       long current = longs.get(i);
       double currentVal = longBitsToDouble(current);
-      double nextVal = currentVal + delta;
+      double nextVal = updaterFunction.applyAsDouble(currentVal);
       long next = doubleToRawLongBits(nextVal);
       if (longs.compareAndSet(i, current, next)) {
         return nextVal;
diff --git a/guava/src/com/google/common/util/concurrent/AtomicLongMap.java b/guava/src/com/google/common/util/concurrent/AtomicLongMap.java
index b80ef2eba445..456b3aceb1ac 100644
--- a/guava/src/com/google/common/util/concurrent/AtomicLongMap.java
+++ b/guava/src/com/google/common/util/concurrent/AtomicLongMap.java
@@ -29,7 +29,7 @@
 import java.util.concurrent.atomic.AtomicLong;
 import java.util.function.LongBinaryOperator;
 import java.util.function.LongUnaryOperator;
-import org.checkerframework.checker.nullness.qual.Nullable;
+import javax.annotation.CheckForNull;
 
 /**
  * A map containing {@code long} values that can be atomically updated. While writes to a
@@ -55,6 +55,7 @@
  * @since 11.0
  */
 @GwtCompatible
+@ElementTypesAreNonnullByDefault
 public final class AtomicLongMap<K> implements Serializable {
   private final ConcurrentHashMap<K, Long> map;
 
@@ -262,7 +263,7 @@ public long sum() {
     return map.values().stream().mapToLong(Long::longValue).sum();
   }
 
-  private transient @Nullable Map<K, Long> asMap;
+  @CheckForNull private transient Map<K, Long> asMap;
 
   /** Returns a live, read-only view of the map backing this {@code AtomicLongMap}. */
   public Map<K, Long> asMap() {
diff --git a/guava/src/com/google/common/util/concurrent/Atomics.java b/guava/src/com/google/common/util/concurrent/Atomics.java
index 191da95bd397..c1b6964ec23c 100644
--- a/guava/src/com/google/common/util/concurrent/Atomics.java
+++ b/guava/src/com/google/common/util/concurrent/Atomics.java
@@ -26,6 +26,7 @@
  * @since 10.0
  */
 @GwtIncompatible
+@ElementTypesAreNonnullByDefault
 public final class Atomics {
   private Atomics() {}
 
@@ -34,8 +35,8 @@ private Atomics() {}
    *
    * @return a new {@code AtomicReference} with no initial value
    */
-  public static <V> AtomicReference<V> newReference() {
-    return new AtomicReference<V>();
+  public static <V> AtomicReference<@Nullable V> newReference() {
+    return new AtomicReference<>();
   }
 
   /**
@@ -44,8 +45,9 @@ public static <V> AtomicReference<V> newReference() {
    * @param initialValue the initial value
    * @return a new {@code AtomicReference} with the given initial value
    */
-  public static <V> AtomicReference<V> newReference(@Nullable V initialValue) {
-    return new AtomicReference<V>(initialValue);
+  public static <V extends @Nullable Object> AtomicReference<V> newReference(
+      @ParametricNullness V initialValue) {
+    return new AtomicReference<>(initialValue);
   }
 
   /**
@@ -54,8 +56,8 @@ public static <V> AtomicReference<V> newReference(@Nullable V initialValue) {
    * @param length the length of the array
    * @return a new {@code AtomicReferenceArray} with the given length
    */
-  public static <E> AtomicReferenceArray<E> newReferenceArray(int length) {
-    return new AtomicReferenceArray<E>(length);
+  public static <E> AtomicReferenceArray<@Nullable E> newReferenceArray(int length) {
+    return new AtomicReferenceArray<>(length);
   }
 
   /**
@@ -65,7 +67,7 @@ public static <E> AtomicReferenceArray<E> newReferenceArray(int length) {
    * @param array the array to copy elements from
    * @return a new {@code AtomicReferenceArray} copied from the given array
    */
-  public static <E> AtomicReferenceArray<E> newReferenceArray(E[] array) {
-    return new AtomicReferenceArray<E>(array);
+  public static <E extends @Nullable Object> AtomicReferenceArray<E> newReferenceArray(E[] array) {
+    return new AtomicReferenceArray<>(array);
   }
 }
diff --git a/guava/src/com/google/common/util/concurrent/Callables.java b/guava/src/com/google/common/util/concurrent/Callables.java
index 89909b4a8fc5..3b52c2e98217 100644
--- a/guava/src/com/google/common/util/concurrent/Callables.java
+++ b/guava/src/com/google/common/util/concurrent/Callables.java
@@ -30,17 +30,13 @@
  * @since 1.0
  */
 @GwtCompatible(emulated = true)
+@ElementTypesAreNonnullByDefault
 public final class Callables {
   private Callables() {}
 
   /** Creates a {@code Callable} which immediately returns a preset value each time it is called. */
-  public static <T> Callable<T> returning(final @Nullable T value) {
-    return new Callable<T>() {
-      @Override
-      public T call() {
-        return value;
-      }
-    };
+  public static <T extends @Nullable Object> Callable<T> returning(@ParametricNullness T value) {
+    return () -> value;
   }
 
   /**
@@ -53,16 +49,11 @@ public T call() {
    */
   @Beta
   @GwtIncompatible
-  public static <T> AsyncCallable<T> asAsyncCallable(
-      final Callable<T> callable, final ListeningExecutorService listeningExecutorService) {
+  public static <T extends @Nullable Object> AsyncCallable<T> asAsyncCallable(
+      Callable<T> callable, ListeningExecutorService listeningExecutorService) {
     checkNotNull(callable);
     checkNotNull(listeningExecutorService);
-    return new AsyncCallable<T>() {
-      @Override
-      public ListenableFuture<T> call() throws Exception {
-        return listeningExecutorService.submit(callable);
-      }
-    };
+    return () -> listeningExecutorService.submit(callable);
   }
 
   /**
@@ -74,22 +65,19 @@ public ListenableFuture<T> call() throws Exception {
    *     for each invocation of the wrapped callable.
    */
   @GwtIncompatible // threads
-  static <T> Callable<T> threadRenaming(
-      final Callable<T> callable, final Supplier<String> nameSupplier) {
+  static <T extends @Nullable Object> Callable<T> threadRenaming(
+      Callable<T> callable, Supplier<String> nameSupplier) {
     checkNotNull(nameSupplier);
     checkNotNull(callable);
-    return new Callable<T>() {
-      @Override
-      public T call() throws Exception {
-        Thread currentThread = Thread.currentThread();
-        String oldName = currentThread.getName();
-        boolean restoreName = trySetName(nameSupplier.get(), currentThread);
-        try {
-          return callable.call();
-        } finally {
-          if (restoreName) {
-            boolean unused = trySetName(oldName, currentThread);
-          }
+    return () -> {
+      Thread currentThread = Thread.currentThread();
+      String oldName = currentThread.getName();
+      boolean restoreName = trySetName(nameSupplier.get(), currentThread);
+      try {
+        return callable.call();
+      } finally {
+        if (restoreName) {
+          boolean unused = trySetName(oldName, currentThread);
         }
       }
     };
@@ -104,21 +92,18 @@ public T call() throws Exception {
    *     for each invocation of the wrapped callable.
    */
   @GwtIncompatible // threads
-  static Runnable threadRenaming(final Runnable task, final Supplier<String> nameSupplier) {
+  static Runnable threadRenaming(Runnable task, Supplier<String> nameSupplier) {
     checkNotNull(nameSupplier);
     checkNotNull(task);
-    return new Runnable() {
-      @Override
-      public void run() {
-        Thread currentThread = Thread.currentThread();
-        String oldName = currentThread.getName();
-        boolean restoreName = trySetName(nameSupplier.get(), currentThread);
-        try {
-          task.run();
-        } finally {
-          if (restoreName) {
-            boolean unused = trySetName(oldName, currentThread);
-          }
+    return () -> {
+      Thread currentThread = Thread.currentThread();
+      String oldName = currentThread.getName();
+      boolean restoreName = trySetName(nameSupplier.get(), currentThread);
+      try {
+        task.run();
+      } finally {
+        if (restoreName) {
+          boolean unused = trySetName(oldName, currentThread);
         }
       }
     };
@@ -126,7 +111,7 @@ public void run() {
 
   /** Tries to set name of the given {@link Thread}, returns true if successful. */
   @GwtIncompatible // threads
-  private static boolean trySetName(final String threadName, Thread currentThread) {
+  private static boolean trySetName(String threadName, Thread currentThread) {
     /*
      * setName should usually succeed, but the security manager can prohibit it. Is there a way to
      * see if we have the modifyThread permission without catching an exception?
diff --git a/guava/src/com/google/common/util/concurrent/ClosingFuture.java b/guava/src/com/google/common/util/concurrent/ClosingFuture.java
index f2a315875395..fbd604ceadfe 100644
--- a/guava/src/com/google/common/util/concurrent/ClosingFuture.java
+++ b/guava/src/com/google/common/util/concurrent/ClosingFuture.java
@@ -36,7 +36,6 @@
 import static java.util.logging.Level.SEVERE;
 import static java.util.logging.Level.WARNING;
 
-import com.google.common.annotations.Beta;
 import com.google.common.annotations.VisibleForTesting;
 import com.google.common.base.Function;
 import com.google.common.collect.FluentIterable;
@@ -59,6 +58,7 @@
 import java.util.concurrent.RejectedExecutionException;
 import java.util.concurrent.atomic.AtomicReference;
 import java.util.logging.Logger;
+import javax.annotation.CheckForNull;
 import org.checkerframework.checker.nullness.qual.Nullable;
 
 /**
@@ -189,10 +189,10 @@
  * @since 30.0
  */
 // TODO(dpb): Consider reusing one CloseableList for the entire pipeline, modulo combinations.
-@Beta // @Beta for one release.
 @DoNotMock("Use ClosingFuture.from(Futures.immediate*Future)")
+@ElementTypesAreNonnullByDefault
 // TODO(dpb): GWT compatibility.
-public final class ClosingFuture<V> {
+public final class ClosingFuture<V extends @Nullable Object> {
 
   private static final Logger logger = Logger.getLogger(ClosingFuture.class.getName());
 
@@ -231,8 +231,9 @@ public static final class DeferredCloser {
      * @return the first argument
      */
     @CanIgnoreReturnValue
+    @ParametricNullness
     public <C extends @Nullable Object & @Nullable AutoCloseable> C eventuallyClose(
-        C closeable, Executor closingExecutor) {
+        @ParametricNullness C closeable, Executor closingExecutor) {
       checkNotNull(closingExecutor);
       if (closeable != null) {
         list.add(closeable, closingExecutor);
@@ -255,6 +256,7 @@ public interface ClosingCallable<V extends @Nullable Object> {
      * closer.eventuallyClose()} will be closed when the {@link ClosingFuture} pipeline is done (but
      * not before this method completes), even if this method throws or the pipeline is cancelled.
      */
+    @ParametricNullness
     V call(DeferredCloser closer) throws Exception;
   }
 
@@ -292,7 +294,8 @@ public interface ClosingFunction<T extends @Nullable Object, U extends @Nullable
      * closer.eventuallyClose()} will be closed when the {@link ClosingFuture} pipeline is done (but
      * not before this method completes), even if this method throws or the pipeline is cancelled.
      */
-    U apply(DeferredCloser closer, T input) throws Exception;
+    @ParametricNullness
+    U apply(DeferredCloser closer, @ParametricNullness T input) throws Exception;
   }
 
   /**
@@ -310,7 +313,7 @@ public interface AsyncClosingFunction<T extends @Nullable Object, U extends @Nul
      * closer.eventuallyClose()} will be closed when the {@link ClosingFuture} pipeline is done (but
      * not before this method completes), even if this method throws or the pipeline is cancelled.
      */
-    ClosingFuture<U> apply(DeferredCloser closer, T input) throws Exception;
+    ClosingFuture<U> apply(DeferredCloser closer, @ParametricNullness T input) throws Exception;
   }
 
   /**
@@ -323,7 +326,7 @@ public interface AsyncClosingFunction<T extends @Nullable Object, U extends @Nul
    * @param <V> the type of the value of a successful operation
    * @see ClosingFuture#finishToValueAndCloser(ValueAndCloserConsumer, Executor)
    */
-  public static final class ValueAndCloser<V> {
+  public static final class ValueAndCloser<V extends @Nullable Object> {
 
     private final ClosingFuture<? extends V> closingFuture;
 
@@ -341,7 +344,8 @@ public static final class ValueAndCloser<V> {
      * @throws CancellationException if the computation was cancelled
      * @throws ExecutionException if the computation threw an exception
      */
-    public @Nullable V get() throws ExecutionException {
+    @ParametricNullness
+    public V get() throws ExecutionException {
       return getDone(closingFuture.future);
     }
 
@@ -368,7 +372,7 @@ public void closeAsync() {
    * @see ClosingFuture#finishToValueAndCloser(ValueAndCloserConsumer, Executor)
    */
   @FunctionalInterface
-  public interface ValueAndCloserConsumer<V> {
+  public interface ValueAndCloserConsumer<V extends @Nullable Object> {
 
     /** Accepts a {@link ValueAndCloser} for the last step in a {@link ClosingFuture} pipeline. */
     void accept(ValueAndCloser<V> valueAndCloser);
@@ -380,7 +384,8 @@ public interface ValueAndCloserConsumer<V> {
    * @throws java.util.concurrent.RejectedExecutionException if the task cannot be scheduled for
    *     execution
    */
-  public static <V> ClosingFuture<V> submit(ClosingCallable<V> callable, Executor executor) {
+  public static <V extends @Nullable Object> ClosingFuture<V> submit(
+      ClosingCallable<V> callable, Executor executor) {
     return new ClosingFuture<>(callable, executor);
   }
 
@@ -391,7 +396,7 @@ public static <V> ClosingFuture<V> submit(ClosingCallable<V> callable, Executor
    *     execution
    * @since 30.1
    */
-  public static <V> ClosingFuture<V> submitAsync(
+  public static <V extends @Nullable Object> ClosingFuture<V> submitAsync(
       AsyncClosingCallable<V> callable, Executor executor) {
     return new ClosingFuture<>(callable, executor);
   }
@@ -403,7 +408,7 @@ public static <V> ClosingFuture<V> submitAsync(
    * implements {@link Closeable}. In order to start a pipeline with a value that will be closed
    * when the pipeline is done, use {@link #submit(ClosingCallable, Executor)} instead.
    */
-  public static <V> ClosingFuture<V> from(ListenableFuture<V> future) {
+  public static <V extends @Nullable Object> ClosingFuture<V> from(ListenableFuture<V> future) {
     return new ClosingFuture<V>(future);
   }
 
@@ -438,7 +443,7 @@ ClosingFuture<C> eventuallyClosing(
         future,
         new FutureCallback<@Nullable AutoCloseable>() {
           @Override
-          public void onSuccess(@Nullable AutoCloseable result) {
+          public void onSuccess(@CheckForNull AutoCloseable result) {
             closingFuture.closeables.closer.eventuallyClose(result, closingExecutor);
           }
 
@@ -491,8 +496,8 @@ public static Combiner whenAllSucceed(Iterable<? extends ClosingFuture<?>> futur
    * @throws IllegalStateException if a {@code ClosingFuture} has already been derived from any of
    *     the arguments, or if any has already been {@linkplain #finishToFuture() finished}
    */
-  public static <V1, V2> Combiner2<V1, V2> whenAllSucceed(
-      ClosingFuture<V1> future1, ClosingFuture<V2> future2) {
+  public static <V1 extends @Nullable Object, V2 extends @Nullable Object>
+      Combiner2<V1, V2> whenAllSucceed(ClosingFuture<V1> future1, ClosingFuture<V2> future2) {
     return new Combiner2<>(future1, future2);
   }
 
@@ -506,8 +511,10 @@ public static <V1, V2> Combiner2<V1, V2> whenAllSucceed(
    * @throws IllegalStateException if a {@code ClosingFuture} has already been derived from any of
    *     the arguments, or if any has already been {@linkplain #finishToFuture() finished}
    */
-  public static <V1, V2, V3> Combiner3<V1, V2, V3> whenAllSucceed(
-      ClosingFuture<V1> future1, ClosingFuture<V2> future2, ClosingFuture<V3> future3) {
+  public static <
+          V1 extends @Nullable Object, V2 extends @Nullable Object, V3 extends @Nullable Object>
+      Combiner3<V1, V2, V3> whenAllSucceed(
+          ClosingFuture<V1> future1, ClosingFuture<V2> future2, ClosingFuture<V3> future3) {
     return new Combiner3<>(future1, future2, future3);
   }
 
@@ -521,11 +528,16 @@ public static <V1, V2, V3> Combiner3<V1, V2, V3> whenAllSucceed(
    * @throws IllegalStateException if a {@code ClosingFuture} has already been derived from any of
    *     the arguments, or if any has already been {@linkplain #finishToFuture() finished}
    */
-  public static <V1, V2, V3, V4> Combiner4<V1, V2, V3, V4> whenAllSucceed(
-      ClosingFuture<V1> future1,
-      ClosingFuture<V2> future2,
-      ClosingFuture<V3> future3,
-      ClosingFuture<V4> future4) {
+  public static <
+          V1 extends @Nullable Object,
+          V2 extends @Nullable Object,
+          V3 extends @Nullable Object,
+          V4 extends @Nullable Object>
+      Combiner4<V1, V2, V3, V4> whenAllSucceed(
+          ClosingFuture<V1> future1,
+          ClosingFuture<V2> future2,
+          ClosingFuture<V3> future3,
+          ClosingFuture<V4> future4) {
     return new Combiner4<>(future1, future2, future3, future4);
   }
 
@@ -539,12 +551,18 @@ public static <V1, V2, V3, V4> Combiner4<V1, V2, V3, V4> whenAllSucceed(
    * @throws IllegalStateException if a {@code ClosingFuture} has already been derived from any of
    *     the arguments, or if any has already been {@linkplain #finishToFuture() finished}
    */
-  public static <V1, V2, V3, V4, V5> Combiner5<V1, V2, V3, V4, V5> whenAllSucceed(
-      ClosingFuture<V1> future1,
-      ClosingFuture<V2> future2,
-      ClosingFuture<V3> future3,
-      ClosingFuture<V4> future4,
-      ClosingFuture<V5> future5) {
+  public static <
+          V1 extends @Nullable Object,
+          V2 extends @Nullable Object,
+          V3 extends @Nullable Object,
+          V4 extends @Nullable Object,
+          V5 extends @Nullable Object>
+      Combiner5<V1, V2, V3, V4, V5> whenAllSucceed(
+          ClosingFuture<V1> future1,
+          ClosingFuture<V2> future2,
+          ClosingFuture<V3> future3,
+          ClosingFuture<V4> future4,
+          ClosingFuture<V5> future5) {
     return new Combiner5<>(future1, future2, future3, future4, future5);
   }
 
@@ -582,6 +600,7 @@ private ClosingFuture(final ClosingCallable<V> callable, Executor executor) {
         TrustedListenableFutureTask.create(
             new Callable<V>() {
               @Override
+              @ParametricNullness
               public V call() throws Exception {
                 return callable.call(closeables.closer);
               }
@@ -669,7 +688,7 @@ public ListenableFuture<?> statusFuture() {
    *     one, or if this {@code ClosingFuture} has already been {@linkplain #finishToFuture()
    *     finished}
    */
-  public <U> ClosingFuture<U> transform(
+  public <U extends @Nullable Object> ClosingFuture<U> transform(
       final ClosingFunction<? super V, U> function, Executor executor) {
     checkNotNull(function);
     AsyncFunction<V, U> applyFunction =
@@ -763,7 +782,7 @@ public String toString() {
    *     one, or if this {@code ClosingFuture} has already been {@linkplain #finishToFuture()
    *     finished}
    */
-  public <U> ClosingFuture<U> transformAsync(
+  public <U extends @Nullable Object> ClosingFuture<U> transformAsync(
       final AsyncClosingFunction<? super V, U> function, Executor executor) {
     checkNotNull(function);
     AsyncFunction<V, U> applyFunction =
@@ -807,8 +826,8 @@ public String toString() {
    * @param function transforms the value of a {@code ClosingFuture} step to a {@link
    *     ListenableFuture} with the value of a derived step
    */
-  public static <V, U> AsyncClosingFunction<V, U> withoutCloser(
-      final AsyncFunction<V, U> function) {
+  public static <V extends @Nullable Object, U extends @Nullable Object>
+      AsyncClosingFunction<V, U> withoutCloser(final AsyncFunction<V, U> function) {
     checkNotNull(function);
     return new AsyncClosingFunction<V, U>() {
       @Override
@@ -1077,7 +1096,7 @@ public void run() {
         executor);
   }
 
-  private static <C, V extends C> void provideValueAndCloser(
+  private static <C extends @Nullable Object, V extends C> void provideValueAndCloser(
       ValueAndCloserConsumer<C> consumer, ClosingFuture<V> closingFuture) {
     consumer.accept(new ValueAndCloser<C>(closingFuture));
   }
@@ -1113,7 +1132,7 @@ private void close() {
     closeables.close();
   }
 
-  private <U> ClosingFuture<U> derive(FluentFuture<U> future) {
+  private <U extends @Nullable Object> ClosingFuture<U> derive(FluentFuture<U> future) {
     ClosingFuture<U> derived = new ClosingFuture<>(future);
     becomeSubsumedInto(derived.closeables);
     return derived;
@@ -1149,6 +1168,7 @@ private Peeker(ImmutableList<ClosingFuture<?>> futures) {
      *     CombiningCallable#call(DeferredCloser, Peeker)} or {@link
      *     AsyncCombiningCallable#call(DeferredCloser, Peeker)}
      */
+    @ParametricNullness
     public final <D extends @Nullable Object> D getDone(ClosingFuture<D> closingFuture)
         throws ExecutionException {
       checkState(beingCalled);
@@ -1156,6 +1176,7 @@ private Peeker(ImmutableList<ClosingFuture<?>> futures) {
       return Futures.getDone(closingFuture.future);
     }
 
+    @ParametricNullness
     private <V extends @Nullable Object> V call(
         CombiningCallable<V> combiner, CloseableList closeables) throws Exception {
       beingCalled = true;
@@ -1230,6 +1251,7 @@ public interface CombiningCallable<V extends @Nullable Object> {
        *
        * @param peeker used to get the value of any of the input futures
        */
+      @ParametricNullness
       V call(DeferredCloser closer, Peeker peeker) throws Exception;
     }
 
@@ -1278,11 +1300,12 @@ private Combiner(boolean allMustSucceed, Iterable<? extends ClosingFuture<?>> in
      * <p>If the combiningCallable throws an {@code ExecutionException}, the cause of the thrown
      * {@code ExecutionException} will be extracted and used as the failure of the derived step.
      */
-    public <V> ClosingFuture<V> call(
+    public <V extends @Nullable Object> ClosingFuture<V> call(
         final CombiningCallable<V> combiningCallable, Executor executor) {
       Callable<V> callable =
           new Callable<V>() {
             @Override
+            @ParametricNullness
             public V call() throws Exception {
               return new Peeker(inputs).call(combiningCallable, closeables);
             }
@@ -1334,7 +1357,7 @@ public String toString() {
      * <p>The same warnings about doing heavyweight operations within {@link
      * ClosingFuture#transformAsync(AsyncClosingFunction, Executor)} apply here.
      */
-    public <V> ClosingFuture<V> callAsync(
+    public <V extends @Nullable Object> ClosingFuture<V> callAsync(
         final AsyncCombiningCallable<V> combiningCallable, Executor executor) {
       AsyncCallable<V> asyncCallable =
           new AsyncCallable<V>() {
@@ -1354,7 +1377,7 @@ public String toString() {
       return derived;
     }
 
-    private FutureCombiner<Object> futureCombiner() {
+    private FutureCombiner<@Nullable Object> futureCombiner() {
       return allMustSucceed
           ? Futures.whenAllSucceed(inputFutures())
           : Futures.whenAllComplete(inputFutures());
@@ -1404,7 +1427,9 @@ public interface ClosingFunction2<
        * is done (but not before this method completes), even if this method throws or the pipeline
        * is cancelled.
        */
-      U apply(DeferredCloser closer, V1 value1, V2 value2) throws Exception;
+      @ParametricNullness
+      U apply(DeferredCloser closer, @ParametricNullness V1 value1, @ParametricNullness V2 value2)
+          throws Exception;
     }
 
     /**
@@ -1427,7 +1452,9 @@ public interface AsyncClosingFunction2<
        * is done (but not before this method completes), even if this method throws or the pipeline
        * is cancelled.
        */
-      ClosingFuture<U> apply(DeferredCloser closer, V1 value1, V2 value2) throws Exception;
+      ClosingFuture<U> apply(
+          DeferredCloser closer, @ParametricNullness V1 value1, @ParametricNullness V2 value2)
+          throws Exception;
     }
 
     private final ClosingFuture<V1> future1;
@@ -1457,6 +1484,7 @@ private Combiner2(ClosingFuture<V1> future1, ClosingFuture<V2> future2) {
       return call(
           new CombiningCallable<U>() {
             @Override
+            @ParametricNullness
             public U call(DeferredCloser closer, Peeker peeker) throws Exception {
               return function.apply(closer, peeker.getDone(future1), peeker.getDone(future2));
             }
@@ -1558,7 +1586,13 @@ public interface ClosingFunction3<
        * is done (but not before this method completes), even if this method throws or the pipeline
        * is cancelled.
        */
-      U apply(DeferredCloser closer, V1 value1, V2 value2, V3 v3) throws Exception;
+      @ParametricNullness
+      U apply(
+          DeferredCloser closer,
+          @ParametricNullness V1 value1,
+          @ParametricNullness V2 value2,
+          @ParametricNullness V3 value3)
+          throws Exception;
     }
 
     /**
@@ -1584,7 +1618,11 @@ public interface AsyncClosingFunction3<
        * is done (but not before this method completes), even if this method throws or the pipeline
        * is cancelled.
        */
-      ClosingFuture<U> apply(DeferredCloser closer, V1 value1, V2 value2, V3 value3)
+      ClosingFuture<U> apply(
+          DeferredCloser closer,
+          @ParametricNullness V1 value1,
+          @ParametricNullness V2 value2,
+          @ParametricNullness V3 value3)
           throws Exception;
     }
 
@@ -1618,6 +1656,7 @@ private Combiner3(
       return call(
           new CombiningCallable<U>() {
             @Override
+            @ParametricNullness
             public U call(DeferredCloser closer, Peeker peeker) throws Exception {
               return function.apply(
                   closer,
@@ -1733,7 +1772,14 @@ public interface ClosingFunction4<
        * is done (but not before this method completes), even if this method throws or the pipeline
        * is cancelled.
        */
-      U apply(DeferredCloser closer, V1 value1, V2 value2, V3 value3, V4 value4) throws Exception;
+      @ParametricNullness
+      U apply(
+          DeferredCloser closer,
+          @ParametricNullness V1 value1,
+          @ParametricNullness V2 value2,
+          @ParametricNullness V3 value3,
+          @ParametricNullness V4 value4)
+          throws Exception;
     }
 
     /**
@@ -1762,7 +1808,12 @@ public interface AsyncClosingFunction4<
        * is done (but not before this method completes), even if this method throws or the pipeline
        * is cancelled.
        */
-      ClosingFuture<U> apply(DeferredCloser closer, V1 value1, V2 value2, V3 value3, V4 value4)
+      ClosingFuture<U> apply(
+          DeferredCloser closer,
+          @ParametricNullness V1 value1,
+          @ParametricNullness V2 value2,
+          @ParametricNullness V3 value3,
+          @ParametricNullness V4 value4)
           throws Exception;
     }
 
@@ -1801,6 +1852,7 @@ private Combiner4(
       return call(
           new CombiningCallable<U>() {
             @Override
+            @ParametricNullness
             public U call(DeferredCloser closer, Peeker peeker) throws Exception {
               return function.apply(
                   closer,
@@ -1923,7 +1975,14 @@ public interface ClosingFunction5<
        * is done (but not before this method completes), even if this method throws or the pipeline
        * is cancelled.
        */
-      U apply(DeferredCloser closer, V1 value1, V2 value2, V3 value3, V4 value4, V5 value5)
+      @ParametricNullness
+      U apply(
+          DeferredCloser closer,
+          @ParametricNullness V1 value1,
+          @ParametricNullness V2 value2,
+          @ParametricNullness V3 value3,
+          @ParametricNullness V4 value4,
+          @ParametricNullness V5 value5)
           throws Exception;
     }
 
@@ -1956,7 +2015,12 @@ public interface AsyncClosingFunction5<
        * is cancelled.
        */
       ClosingFuture<U> apply(
-          DeferredCloser closer, V1 value1, V2 value2, V3 value3, V4 value4, V5 value5)
+          DeferredCloser closer,
+          @ParametricNullness V1 value1,
+          @ParametricNullness V2 value2,
+          @ParametricNullness V3 value3,
+          @ParametricNullness V4 value4,
+          @ParametricNullness V5 value5)
           throws Exception;
     }
 
@@ -1999,6 +2063,7 @@ private Combiner5(
       return call(
           new CombiningCallable<U>() {
             @Override
+            @ParametricNullness
             public U call(DeferredCloser closer, Peeker peeker) throws Exception {
               return function.apply(
                   closer,
@@ -2092,7 +2157,7 @@ protected void finalize() {
     }
   }
 
-  private static void closeQuietly(final AutoCloseable closeable, Executor executor) {
+  private static void closeQuietly(@CheckForNull final AutoCloseable closeable, Executor executor) {
     if (closeable == null) {
       return;
     }
@@ -2134,10 +2199,12 @@ private static final class CloseableList extends IdentityHashMap<AutoCloseable,
       implements Closeable {
     private final DeferredCloser closer = new DeferredCloser(this);
     private volatile boolean closed;
-    private volatile CountDownLatch whenClosed;
+    @CheckForNull private volatile CountDownLatch whenClosed;
 
-    <V, U> ListenableFuture<U> applyClosingFunction(
-        ClosingFunction<? super V, U> transformation, V input) throws Exception {
+    <V extends @Nullable Object, U extends @Nullable Object>
+        ListenableFuture<U> applyClosingFunction(
+            ClosingFunction<? super V, U> transformation, @ParametricNullness V input)
+            throws Exception {
       // TODO(dpb): Consider ways to defer closing without creating a separate CloseableList.
       CloseableList newCloseables = new CloseableList();
       try {
@@ -2147,8 +2214,10 @@ <V, U> ListenableFuture<U> applyClosingFunction(
       }
     }
 
-    <V, U> FluentFuture<U> applyAsyncClosingFunction(
-        AsyncClosingFunction<V, U> transformation, V input) throws Exception {
+    <V extends @Nullable Object, U extends @Nullable Object>
+        FluentFuture<U> applyAsyncClosingFunction(
+            AsyncClosingFunction<V, U> transformation, @ParametricNullness V input)
+            throws Exception {
       // TODO(dpb): Consider ways to defer closing without creating a separate CloseableList.
       CloseableList newCloseables = new CloseableList();
       try {
@@ -2180,7 +2249,7 @@ public void close() {
       }
     }
 
-    void add(@Nullable AutoCloseable closeable, Executor executor) {
+    void add(@CheckForNull AutoCloseable closeable, Executor executor) {
       checkNotNull(executor);
       if (closeable == null) {
         return;
diff --git a/guava/src/com/google/common/util/concurrent/CollectionFuture.java b/guava/src/com/google/common/util/concurrent/CollectionFuture.java
index 9cdf46f4b118..c106c157e257 100644
--- a/guava/src/com/google/common/util/concurrent/CollectionFuture.java
+++ b/guava/src/com/google/common/util/concurrent/CollectionFuture.java
@@ -19,31 +19,34 @@
 
 import com.google.common.annotations.GwtCompatible;
 import com.google.common.collect.ImmutableCollection;
-import com.google.common.collect.ImmutableList;
 import com.google.common.collect.Lists;
+import java.util.Collections;
 import java.util.List;
+import javax.annotation.CheckForNull;
 import org.checkerframework.checker.nullness.qual.Nullable;
 
 /** Aggregate future that collects (stores) results of each future. */
 @GwtCompatible(emulated = true)
-abstract class CollectionFuture<V, C> extends AggregateFuture<V, C> {
+@ElementTypesAreNonnullByDefault
+abstract class CollectionFuture<V extends @Nullable Object, C extends @Nullable Object>
+    extends AggregateFuture<V, C> {
   /*
    * We access this field racily but safely. For discussion of a similar situation, see the comments
    * on the fields of TimeoutFuture. This field is slightly different than the fields discussed
    * there: cancel() never reads this field, only writes to it. That makes the race here completely
    * harmless, rather than just 99.99% harmless.
    */
-  private List<Present<V>> values;
+  @CheckForNull private List<@Nullable Present<V>> values;
 
   CollectionFuture(
       ImmutableCollection<? extends ListenableFuture<? extends V>> futures,
       boolean allMustSucceed) {
     super(futures, allMustSucceed, true);
 
-    List<Present<V>> values =
+    List<@Nullable Present<V>> values =
         futures.isEmpty()
-            ? ImmutableList.<Present<V>>of()
-            : Lists.<Present<V>>newArrayListWithCapacity(futures.size());
+            ? Collections.<@Nullable Present<V>>emptyList()
+            : Lists.<@Nullable Present<V>>newArrayListWithCapacity(futures.size());
 
     // Populate the results list with null initially.
     for (int i = 0; i < futures.size(); ++i) {
@@ -54,8 +57,8 @@ abstract class CollectionFuture<V, C> extends AggregateFuture<V, C> {
   }
 
   @Override
-  final void collectOneValue(int index, @Nullable V returnValue) {
-    List<Present<V>> localValues = values;
+  final void collectOneValue(int index, @ParametricNullness V returnValue) {
+    List<@Nullable Present<V>> localValues = values;
     if (localValues != null) {
       localValues.set(index, new Present<>(returnValue));
     }
@@ -63,7 +66,7 @@ final void collectOneValue(int index, @Nullable V returnValue) {
 
   @Override
   final void handleAllCompleted() {
-    List<Present<V>> localValues = values;
+    List<@Nullable Present<V>> localValues = values;
     if (localValues != null) {
       set(combine(localValues));
     }
@@ -75,10 +78,11 @@ void releaseResources(ReleaseResourcesReason reason) {
     this.values = null;
   }
 
-  abstract C combine(List<Present<V>> values);
+  abstract C combine(List<@Nullable Present<V>> values);
 
   /** Used for {@link Futures#allAsList} and {@link Futures#successfulAsList}. */
-  static final class ListFuture<V> extends CollectionFuture<V, List<V>> {
+  static final class ListFuture<V extends @Nullable Object>
+      extends CollectionFuture<V, List<@Nullable V>> {
     ListFuture(
         ImmutableCollection<? extends ListenableFuture<? extends V>> futures,
         boolean allMustSucceed) {
@@ -87,8 +91,8 @@ static final class ListFuture<V> extends CollectionFuture<V, List<V>> {
     }
 
     @Override
-    public List<V> combine(List<Present<V>> values) {
-      List<V> result = newArrayListWithCapacity(values.size());
+    public List<@Nullable V> combine(List<@Nullable Present<V>> values) {
+      List<@Nullable V> result = newArrayListWithCapacity(values.size());
       for (Present<V> element : values) {
         result.add(element != null ? element.value : null);
       }
@@ -97,7 +101,7 @@ public List<V> combine(List<Present<V>> values) {
   }
 
   /** The result of a successful {@code Future}. */
-  private static final class Present<V> {
+  private static final class Present<V extends @Nullable Object> {
     V value;
 
     Present(V value) {
diff --git a/guava/src/com/google/common/util/concurrent/CombinedFuture.java b/guava/src/com/google/common/util/concurrent/CombinedFuture.java
index b8b0e2c0c32b..c22211164c40 100644
--- a/guava/src/com/google/common/util/concurrent/CombinedFuture.java
+++ b/guava/src/com/google/common/util/concurrent/CombinedFuture.java
@@ -25,12 +25,15 @@
 import java.util.concurrent.ExecutionException;
 import java.util.concurrent.Executor;
 import java.util.concurrent.RejectedExecutionException;
+import javax.annotation.CheckForNull;
 import org.checkerframework.checker.nullness.qual.Nullable;
 
 /** Aggregate future that computes its value by calling a callable. */
 @GwtCompatible
-final class CombinedFuture<V> extends AggregateFuture<Object, V> {
-  private CombinedFutureInterruptibleTask<?> task;
+@ElementTypesAreNonnullByDefault
+final class CombinedFuture<V extends @Nullable Object>
+    extends AggregateFuture<@Nullable Object, V> {
+  @CheckForNull private CombinedFutureInterruptibleTask<?> task;
 
   CombinedFuture(
       ImmutableCollection<? extends ListenableFuture<?>> futures,
@@ -53,7 +56,7 @@ final class CombinedFuture<V> extends AggregateFuture<Object, V> {
   }
 
   @Override
-  void collectOneValue(int index, @Nullable Object returnValue) {}
+  void collectOneValue(int index, @CheckForNull Object returnValue) {}
 
   @Override
   void handleAllCompleted() {
@@ -87,7 +90,8 @@ protected void interruptTask() {
   }
 
   @WeakOuter
-  private abstract class CombinedFutureInterruptibleTask<T> extends InterruptibleTask<T> {
+  private abstract class CombinedFutureInterruptibleTask<T extends @Nullable Object>
+      extends InterruptibleTask<T> {
     private final Executor listenerExecutor;
 
     CombinedFutureInterruptibleTask(Executor listenerExecutor) {
@@ -108,7 +112,7 @@ final void execute() {
     }
 
     @Override
-    final void afterRanInterruptibly(T result, Throwable error) {
+    final void afterRanInterruptiblySuccess(@ParametricNullness T result) {
       /*
        * The future no longer needs to interrupt this task, so it no longer needs a reference to it.
        *
@@ -122,20 +126,28 @@ final void afterRanInterruptibly(T result, Throwable error) {
        */
       CombinedFuture.this.task = null;
 
-      if (error != null) {
-        if (error instanceof ExecutionException) {
-          CombinedFuture.this.setException(error.getCause());
-        } else if (error instanceof CancellationException) {
-          cancel(false);
-        } else {
-          CombinedFuture.this.setException(error);
-        }
+      setValue(result);
+    }
+
+    @Override
+    final void afterRanInterruptiblyFailure(Throwable error) {
+      // See afterRanInterruptiblySuccess.
+      CombinedFuture.this.task = null;
+
+      if (error instanceof ExecutionException) {
+        /*
+         * Cast to ExecutionException to satisfy our nullness checker, which (unsoundly but
+         * *usually* safely) assumes that getCause() returns non-null on an ExecutionException.
+         */
+        CombinedFuture.this.setException(((ExecutionException) error).getCause());
+      } else if (error instanceof CancellationException) {
+        cancel(false);
       } else {
-        setValue(result);
+        CombinedFuture.this.setException(error);
       }
     }
 
-    abstract void setValue(T value);
+    abstract void setValue(@ParametricNullness T value);
   }
 
   @WeakOuter
@@ -179,12 +191,13 @@ private final class CallableInterruptibleTask extends CombinedFutureInterruptibl
     }
 
     @Override
+    @ParametricNullness
     V runInterruptibly() throws Exception {
       return callable.call();
     }
 
     @Override
-    void setValue(V value) {
+    void setValue(@ParametricNullness V value) {
       CombinedFuture.this.set(value);
     }
 
diff --git a/guava/src/com/google/common/util/concurrent/CycleDetectingLockFactory.java b/guava/src/com/google/common/util/concurrent/CycleDetectingLockFactory.java
index 67d247867166..decb5f1b183d 100644
--- a/guava/src/com/google/common/util/concurrent/CycleDetectingLockFactory.java
+++ b/guava/src/com/google/common/util/concurrent/CycleDetectingLockFactory.java
@@ -15,6 +15,7 @@
 package com.google.common.util.concurrent;
 
 import static com.google.common.base.Preconditions.checkNotNull;
+import static java.util.Objects.requireNonNull;
 
 import com.google.common.annotations.Beta;
 import com.google.common.annotations.GwtIncompatible;
@@ -42,7 +43,7 @@
 import java.util.concurrent.locks.ReentrantReadWriteLock;
 import java.util.logging.Level;
 import java.util.logging.Logger;
-import org.checkerframework.checker.nullness.qual.Nullable;
+import javax.annotation.CheckForNull;
 
 /**
  * The {@code CycleDetectingLockFactory} creates {@link ReentrantLock} instances and {@link
@@ -162,6 +163,7 @@
 @Beta
 @CanIgnoreReturnValue // TODO(cpovirk): Consider being more strict.
 @GwtIncompatible
+@ElementTypesAreNonnullByDefault
 public class CycleDetectingLockFactory {
 
   /**
@@ -268,7 +270,8 @@ public ReentrantReadWriteLock newReentrantReadWriteLock(String lockName, boolean
   }
 
   // A static mapping from an Enum type to its set of LockGraphNodes.
-  private static final ConcurrentMap<Class<? extends Enum>, Map<? extends Enum, LockGraphNode>>
+  private static final ConcurrentMap<
+          Class<? extends Enum<?>>, Map<? extends Enum<?>, LockGraphNode>>
       lockGraphNodesPerType = new MapMaker().weakKeys().makeMap();
 
   /** Creates a {@code CycleDetectingLockFactory.WithExplicitOrdering<E>}. */
@@ -280,16 +283,18 @@ public static <E extends Enum<E>> WithExplicitOrdering<E> newInstanceWithExplici
     checkNotNull(policy);
     @SuppressWarnings("unchecked")
     Map<E, LockGraphNode> lockGraphNodes = (Map<E, LockGraphNode>) getOrCreateNodes(enumClass);
-    return new WithExplicitOrdering<E>(policy, lockGraphNodes);
+    return new WithExplicitOrdering<>(policy, lockGraphNodes);
   }
 
-  private static Map<? extends Enum, LockGraphNode> getOrCreateNodes(Class<? extends Enum> clazz) {
-    Map<? extends Enum, LockGraphNode> existing = lockGraphNodesPerType.get(clazz);
+  @SuppressWarnings("unchecked")
+  private static <E extends Enum<E>> Map<? extends E, LockGraphNode> getOrCreateNodes(
+      Class<E> clazz) {
+    Map<E, LockGraphNode> existing = (Map<E, LockGraphNode>) lockGraphNodesPerType.get(clazz);
     if (existing != null) {
       return existing;
     }
-    Map<? extends Enum, LockGraphNode> created = createNodes(clazz);
-    existing = lockGraphNodesPerType.putIfAbsent(clazz, created);
+    Map<E, LockGraphNode> created = createNodes(clazz);
+    existing = (Map<E, LockGraphNode>) lockGraphNodesPerType.putIfAbsent(clazz, created);
     return MoreObjects.firstNonNull(existing, created);
   }
 
@@ -303,7 +308,7 @@ private static Map<? extends Enum, LockGraphNode> getOrCreateNodes(Class<? exten
   static <E extends Enum<E>> Map<E, LockGraphNode> createNodes(Class<E> clazz) {
     EnumMap<E, LockGraphNode> map = Maps.newEnumMap(clazz);
     E[] keys = clazz.getEnumConstants();
-    final int numKeys = keys.length;
+    int numKeys = keys.length;
     ArrayList<LockGraphNode> nodes = Lists.newArrayListWithCapacity(numKeys);
     // Create a LockGraphNode for each enum value.
     for (E key : keys) {
@@ -417,7 +422,9 @@ public ReentrantLock newReentrantLock(E rank) {
     public ReentrantLock newReentrantLock(E rank, boolean fair) {
       return policy == Policies.DISABLED
           ? new ReentrantLock(fair)
-          : new CycleDetectingReentrantLock(lockGraphNodes.get(rank), fair);
+          // requireNonNull is safe because createNodes inserts an entry for every E.
+          // (If the caller passes `null` for the `rank` parameter, this will throw, but that's OK.)
+          : new CycleDetectingReentrantLock(requireNonNull(lockGraphNodes.get(rank)), fair);
     }
 
     /** Equivalent to {@code newReentrantReadWriteLock(rank, false)}. */
@@ -436,7 +443,10 @@ public ReentrantReadWriteLock newReentrantReadWriteLock(E rank) {
     public ReentrantReadWriteLock newReentrantReadWriteLock(E rank, boolean fair) {
       return policy == Policies.DISABLED
           ? new ReentrantReadWriteLock(fair)
-          : new CycleDetectingReentrantReadWriteLock(lockGraphNodes.get(rank), fair);
+          // requireNonNull is safe because createNodes inserts an entry for every E.
+          // (If the caller passes `null` for the `rank` parameter, this will throw, but that's OK.)
+          : new CycleDetectingReentrantReadWriteLock(
+              requireNonNull(lockGraphNodes.get(rank)), fair);
     }
   }
 
@@ -546,7 +556,8 @@ public ExampleStackTrace getConflictingStackTrace() {
      */
     @Override
     public String getMessage() {
-      StringBuilder message = new StringBuilder(super.getMessage());
+      // requireNonNull is safe because ExampleStackTrace sets a non-null message.
+      StringBuilder message = new StringBuilder(requireNonNull(super.getMessage()));
       for (Throwable t = conflictingStackTrace; t != null; t = t.getCause()) {
         message.append(", ").append(t.getMessage());
       }
@@ -599,8 +610,8 @@ String getLockName() {
     }
 
     void checkAcquiredLocks(Policy policy, List<LockGraphNode> acquiredLocks) {
-      for (int i = 0, size = acquiredLocks.size(); i < size; i++) {
-        checkAcquiredLock(policy, acquiredLocks.get(i));
+      for (LockGraphNode acquiredLock : acquiredLocks) {
+        checkAcquiredLock(policy, acquiredLock);
       }
     }
 
@@ -674,7 +685,8 @@ void checkAcquiredLock(Policy policy, LockGraphNode acquiredLock) {
      * @return If a path was found, a chained {@link ExampleStackTrace} illustrating the path to the
      *     {@code lock}, or {@code null} if no path was found.
      */
-    private @Nullable ExampleStackTrace findPathTo(LockGraphNode node, Set<LockGraphNode> seen) {
+    @CheckForNull
+    private ExampleStackTrace findPathTo(LockGraphNode node, Set<LockGraphNode> seen) {
       if (!seen.add(this)) {
         return null; // Already traversed this node.
       }
diff --git a/guava/src/com/google/common/util/concurrent/DirectExecutor.java b/guava/src/com/google/common/util/concurrent/DirectExecutor.java
index 30229714c638..0c3a46b703c3 100644
--- a/guava/src/com/google/common/util/concurrent/DirectExecutor.java
+++ b/guava/src/com/google/common/util/concurrent/DirectExecutor.java
@@ -22,6 +22,7 @@
  * execute}.
  */
 @GwtCompatible
+@ElementTypesAreNonnullByDefault
 enum DirectExecutor implements Executor {
   INSTANCE;
 
diff --git a/guava/src/com/google/common/util/concurrent/ElementTypesAreNonnullByDefault.java b/guava/src/com/google/common/util/concurrent/ElementTypesAreNonnullByDefault.java
new file mode 100644
index 000000000000..34871255e812
--- /dev/null
+++ b/guava/src/com/google/common/util/concurrent/ElementTypesAreNonnullByDefault.java
@@ -0,0 +1,41 @@
+/*
+ * Copyright (C) 2021 The Guava Authors
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package com.google.common.util.concurrent;
+
+import static java.lang.annotation.ElementType.FIELD;
+import static java.lang.annotation.ElementType.METHOD;
+import static java.lang.annotation.ElementType.PARAMETER;
+import static java.lang.annotation.ElementType.TYPE;
+import static java.lang.annotation.RetentionPolicy.RUNTIME;
+
+import com.google.common.annotations.GwtCompatible;
+import java.lang.annotation.Retention;
+import java.lang.annotation.Target;
+import javax.annotation.Nonnull;
+import javax.annotation.meta.TypeQualifierDefault;
+
+/**
+ * Marks all "top-level" types as non-null in a way that is recognized by Kotlin. Note that this
+ * unfortunately includes type-variable usages, so we also provide {@link ParametricNullness} to
+ * "undo" it as best we can.
+ */
+@GwtCompatible
+@Retention(RUNTIME)
+@Target(TYPE)
+@TypeQualifierDefault({FIELD, METHOD, PARAMETER})
+@Nonnull
+@interface ElementTypesAreNonnullByDefault {}
diff --git a/guava/src/com/google/common/util/concurrent/ExecutionError.java b/guava/src/com/google/common/util/concurrent/ExecutionError.java
index 7663c15ef0f8..deaff15a426c 100644
--- a/guava/src/com/google/common/util/concurrent/ExecutionError.java
+++ b/guava/src/com/google/common/util/concurrent/ExecutionError.java
@@ -15,7 +15,7 @@
 package com.google.common.util.concurrent;
 
 import com.google.common.annotations.GwtCompatible;
-import org.checkerframework.checker.nullness.qual.Nullable;
+import javax.annotation.CheckForNull;
 
 /**
  * {@link Error} variant of {@link java.util.concurrent.ExecutionException}. As with {@code
@@ -28,22 +28,29 @@
  * @since 10.0
  */
 @GwtCompatible
+@ElementTypesAreNonnullByDefault
 public class ExecutionError extends Error {
+  /*
+   * Ideally, this class would have exposed only constructors that require a non-null cause. We
+   * might try to move in that direction, but there are complications. See
+   * https://github.com/jspecify/nullness-checker-for-checker-framework/blob/61aafa4ae52594830cfc2d61c8b113009dbdb045/src/main/java/com/google/jspecify/nullness/NullSpecTransfer.java#L789
+   */
+
   /** Creates a new instance with {@code null} as its detail message. */
   protected ExecutionError() {}
 
   /** Creates a new instance with the given detail message. */
-  protected ExecutionError(@Nullable String message) {
+  protected ExecutionError(@CheckForNull String message) {
     super(message);
   }
 
   /** Creates a new instance with the given detail message and cause. */
-  public ExecutionError(@Nullable String message, @Nullable Error cause) {
+  public ExecutionError(@CheckForNull String message, @CheckForNull Error cause) {
     super(message, cause);
   }
 
   /** Creates a new instance with the given cause. */
-  public ExecutionError(@Nullable Error cause) {
+  public ExecutionError(@CheckForNull Error cause) {
     super(cause);
   }
 
diff --git a/guava/src/com/google/common/util/concurrent/ExecutionList.java b/guava/src/com/google/common/util/concurrent/ExecutionList.java
index 1ff609b78c98..96fc51ca88d0 100644
--- a/guava/src/com/google/common/util/concurrent/ExecutionList.java
+++ b/guava/src/com/google/common/util/concurrent/ExecutionList.java
@@ -21,7 +21,7 @@
 import java.util.concurrent.Executor;
 import java.util.logging.Level;
 import java.util.logging.Logger;
-import org.checkerframework.checker.nullness.qual.Nullable;
+import javax.annotation.CheckForNull;
 
 /**
  * A support class for {@code ListenableFuture} implementations to manage their listeners. An
@@ -40,6 +40,7 @@
  * @since 1.0
  */
 @GwtIncompatible
+@ElementTypesAreNonnullByDefault
 public final class ExecutionList {
   /** Logger to log exceptions caught when running runnables. */
   private static final Logger log = Logger.getLogger(ExecutionList.class.getName());
@@ -49,7 +50,8 @@ public final class ExecutionList {
    * RunnableExecutorPair#next} field.
    */
   @GuardedBy("this")
-  private @Nullable RunnableExecutorPair runnables;
+  @CheckForNull
+  private RunnableExecutorPair runnables;
 
   @GuardedBy("this")
   private boolean executed;
@@ -153,9 +155,10 @@ private static void executeListener(Runnable runnable, Executor executor) {
   private static final class RunnableExecutorPair {
     final Runnable runnable;
     final Executor executor;
-    @Nullable RunnableExecutorPair next;
+    @CheckForNull RunnableExecutorPair next;
 
-    RunnableExecutorPair(Runnable runnable, Executor executor, RunnableExecutorPair next) {
+    RunnableExecutorPair(
+        Runnable runnable, Executor executor, @CheckForNull RunnableExecutorPair next) {
       this.runnable = runnable;
       this.executor = executor;
       this.next = next;
diff --git a/guava/src/com/google/common/util/concurrent/ExecutionSequencer.java b/guava/src/com/google/common/util/concurrent/ExecutionSequencer.java
index f589e08b0ac1..80c7779342b1 100644
--- a/guava/src/com/google/common/util/concurrent/ExecutionSequencer.java
+++ b/guava/src/com/google/common/util/concurrent/ExecutionSequencer.java
@@ -23,11 +23,13 @@
 import static com.google.common.util.concurrent.Futures.immediateFuture;
 import static com.google.common.util.concurrent.Futures.immediateVoidFuture;
 import static com.google.common.util.concurrent.MoreExecutors.directExecutor;
+import static java.util.Objects.requireNonNull;
 
-import com.google.common.annotations.Beta;
 import java.util.concurrent.Callable;
 import java.util.concurrent.Executor;
 import java.util.concurrent.atomic.AtomicReference;
+import javax.annotation.CheckForNull;
+import org.checkerframework.checker.nullness.qual.Nullable;
 
 /**
  * Serializes execution of tasks, somewhat like an "asynchronous {@code synchronized} block." Each
@@ -36,7 +38,14 @@
  * until the {@code Future} it returned is {@linkplain Future#isDone done} (successful, failed, or
  * cancelled).
  *
- * <p>This class has limited support for cancellation and other "early completion":
+ * <p>This class serializes execution of <i>submitted</i> tasks but not any <i>listeners</i> of
+ * those tasks.
+ *
+ * <p>Submitted tasks have a happens-before order as defined in the Java Language Specification.
+ * Tasks execute with the same happens-before order that the function calls to {@link #submit} and
+ * {@link #submitAsync} that submitted those tasks had.
+ *
+ * <p>This class has limited support for cancellation and other "early completions":
  *
  * <ul>
  *   <li>While calls to {@code submit} and {@code submitAsync} return a {@code Future} that can be
@@ -57,9 +66,6 @@
  *       safe for the next task to start.</i>
  * </ul>
  *
- * <p>An additional limitation: this class serializes execution of <i>tasks</i> but not any
- * <i>listeners</i> of those tasks.
- *
  * <p>This class is similar to {@link MoreExecutors#newSequentialExecutor}. This class is different
  * in a few ways:
  *
@@ -77,7 +83,7 @@
  *
  * @since 26.0
  */
-@Beta
+@ElementTypesAreNonnullByDefault
 public final class ExecutionSequencer {
 
   private ExecutionSequencer() {}
@@ -88,7 +94,7 @@ public static ExecutionSequencer create() {
   }
 
   /** This reference acts as a pointer tracking the head of a linked list of ListenableFutures. */
-  private final AtomicReference<ListenableFuture<Void>> ref =
+  private final AtomicReference<ListenableFuture<@Nullable Void>> ref =
       new AtomicReference<>(immediateVoidFuture());
 
   private ThreadConfinedTaskQueue latestTaskQueue = new ThreadConfinedTaskQueue();
@@ -122,11 +128,11 @@ private static final class ThreadConfinedTaskQueue {
      * All the states where thread != currentThread are identical for our purposes, and so even
      * though it's racy, we don't care which of those values we get, so no need to synchronize.
      */
-    Thread thread;
+    @CheckForNull Thread thread;
     /** Only used by the thread associated with this object */
-    Runnable nextTask;
+    @CheckForNull Runnable nextTask;
     /** Only used by the thread associated with this object */
-    Executor nextExecutor;
+    @CheckForNull Executor nextExecutor;
   }
 
   /**
@@ -136,7 +142,8 @@ private static final class ThreadConfinedTaskQueue {
    * execute, but if the output future is cancelled before {@link Callable#call()} is invoked,
    * {@link Callable#call()} will not be invoked.
    */
-  public <T> ListenableFuture<T> submit(final Callable<T> callable, Executor executor) {
+  public <T extends @Nullable Object> ListenableFuture<T> submit(
+      Callable<T> callable, Executor executor) {
     checkNotNull(callable);
     checkNotNull(executor);
     return submitAsync(
@@ -161,12 +168,12 @@ public String toString() {
    * callable} or a callable that has begun to execute, but if the output future is cancelled before
    * {@link AsyncCallable#call()} is invoked, {@link AsyncCallable#call()} will not be invoked.
    */
-  public <T> ListenableFuture<T> submitAsync(
-      final AsyncCallable<T> callable, final Executor executor) {
+  public <T extends @Nullable Object> ListenableFuture<T> submitAsync(
+      AsyncCallable<T> callable, Executor executor) {
     checkNotNull(callable);
     checkNotNull(executor);
-    final TaskNonReentrantExecutor taskExecutor = new TaskNonReentrantExecutor(executor, this);
-    final AsyncCallable<T> task =
+    TaskNonReentrantExecutor taskExecutor = new TaskNonReentrantExecutor(executor, this);
+    AsyncCallable<T> task =
         new AsyncCallable<T>() {
           @Override
           public ListenableFuture<T> call() throws Exception {
@@ -192,58 +199,55 @@ public String toString() {
      * have completed - namely after oldFuture is done, and taskFuture has either completed or been
      * cancelled before the callable started execution.
      */
-    final SettableFuture<Void> newFuture = SettableFuture.create();
+    SettableFuture<@Nullable Void> newFuture = SettableFuture.create();
 
-    final ListenableFuture<Void> oldFuture = ref.getAndSet(newFuture);
+    ListenableFuture<@Nullable Void> oldFuture = ref.getAndSet(newFuture);
 
     // Invoke our task once the previous future completes.
-    final TrustedListenableFutureTask<T> taskFuture = TrustedListenableFutureTask.create(task);
+    TrustedListenableFutureTask<T> taskFuture = TrustedListenableFutureTask.create(task);
     oldFuture.addListener(taskFuture, taskExecutor);
 
-    final ListenableFuture<T> outputFuture = Futures.nonCancellationPropagating(taskFuture);
+    ListenableFuture<T> outputFuture = Futures.nonCancellationPropagating(taskFuture);
 
     // newFuture's lifetime is determined by taskFuture, which can't complete before oldFuture
     // unless taskFuture is cancelled, in which case it falls back to oldFuture. This ensures that
     // if the future we return is cancelled, we don't begin execution of the next task until after
     // oldFuture completes.
     Runnable listener =
-        new Runnable() {
-          @Override
-          public void run() {
-            if (taskFuture.isDone()) {
-              // Since the value of oldFuture can only ever be immediateFuture(null) or setFuture of
-              // a future that eventually came from immediateFuture(null), this doesn't leak
-              // throwables or completion values.
-              newFuture.setFuture(oldFuture);
-            } else if (outputFuture.isCancelled() && taskExecutor.trySetCancelled()) {
-              // If this CAS succeeds, we know that the provided callable will never be invoked,
-              // so when oldFuture completes it is safe to allow the next submitted task to
-              // proceed. Doing this immediately here lets the next task run without waiting for
-              // the cancelled task's executor to run the noop AsyncCallable.
-              //
-              // ---
-              //
-              // If the CAS fails, the provided callable already started running (or it is about
-              // to). Our contract promises:
-              //
-              // 1. not to execute a new callable until the old one has returned
-              //
-              // If we were to cancel taskFuture, that would let the next task start while the old
-              // one is still running.
-              //
-              // Now, maybe we could tweak our implementation to not start the next task until the
-              // callable actually completes. (We could detect completion in our wrapper
-              // `AsyncCallable task`.) However, our contract also promises:
-              //
-              // 2. not to cancel any Future the user returned from an AsyncCallable
-              //
-              // We promise this because, once we cancel that Future, we would no longer be able to
-              // tell when any underlying work it is doing is done. Thus, we might start a new task
-              // while that underlying work is still running.
-              //
-              // So that is why we cancel only in the case of CAS success.
-              taskFuture.cancel(false);
-            }
+        () -> {
+          if (taskFuture.isDone()) {
+            // Since the value of oldFuture can only ever be immediateFuture(null) or setFuture of
+            // a future that eventually came from immediateFuture(null), this doesn't leak
+            // throwables or completion values.
+            newFuture.setFuture(oldFuture);
+          } else if (outputFuture.isCancelled() && taskExecutor.trySetCancelled()) {
+            // If this CAS succeeds, we know that the provided callable will never be invoked,
+            // so when oldFuture completes it is safe to allow the next submitted task to
+            // proceed. Doing this immediately here lets the next task run without waiting for
+            // the cancelled task's executor to run the noop AsyncCallable.
+            //
+            // ---
+            //
+            // If the CAS fails, the provided callable already started running (or it is about
+            // to). Our contract promises:
+            //
+            // 1. not to execute a new callable until the old one has returned
+            //
+            // If we were to cancel taskFuture, that would let the next task start while the old
+            // one is still running.
+            //
+            // Now, maybe we could tweak our implementation to not start the next task until the
+            // callable actually completes. (We could detect completion in our wrapper
+            // `AsyncCallable task`.) However, our contract also promises:
+            //
+            // 2. not to cancel any Future the user returned from an AsyncCallable
+            //
+            // We promise this because, once we cancel that Future, we would no longer be able to
+            // tell when any underlying work it is doing is done. Thus, we might start a new task
+            // while that underlying work is still running.
+            //
+            // So that is why we cancel only in the case of CAS success.
+            taskFuture.cancel(false);
           }
         };
     // Adding the listener to both futures guarantees that newFuture will aways be set. Adding to
@@ -279,7 +283,6 @@ enum RunningState {
    * properties; for example, calling WeakReference.get() on Android will block during an
    * otherwise-concurrent GC cycle.
    */
-  @SuppressWarnings("ShouldNotSubclass") // Saving an allocation here is worth it
   private static final class TaskNonReentrantExecutor extends AtomicReference<RunningState>
       implements Executor, Runnable {
 
@@ -287,22 +290,22 @@ private static final class TaskNonReentrantExecutor extends AtomicReference<Runn
      * Used to update and read the latestTaskQueue field. Set to null once the runnable has been run
      * or queued.
      */
-    ExecutionSequencer sequencer;
+    @CheckForNull ExecutionSequencer sequencer;
 
     /**
      * Executor the task was set to run on. Set to null when the task has been queued, run, or
      * cancelled.
      */
-    Executor delegate;
+    @CheckForNull Executor delegate;
 
     /**
      * Set before calling delegate.execute(); set to null once run, so that it can be GCed; this
      * object may live on after, if submitAsync returns an incomplete future.
      */
-    Runnable task;
+    @CheckForNull Runnable task;
 
     /** Thread that called execute(). Set in execute, cleared when delegate.execute() returns. */
-    Thread submitting;
+    @CheckForNull Thread submitting;
 
     private TaskNonReentrantExecutor(Executor delegate, ExecutionSequencer sequencer) {
       super(NOT_RUN);
@@ -327,8 +330,18 @@ public void execute(Runnable task) {
         return;
       }
       submitting = Thread.currentThread();
+
       try {
-        ThreadConfinedTaskQueue submittingTaskQueue = sequencer.latestTaskQueue;
+        /*
+         * requireNonNull is safe because we don't null out `sequencer` except:
+         *
+         * - above, where we return (in which case we never get here)
+         *
+         * - in `run`, which can't run until this Runnable is submitted to an executor, which
+         *   doesn't happen until below. (And this Executor -- yes, the object is both a Runnable
+         *   and an Executor -- is used for only a single `execute` call.)
+         */
+        ThreadConfinedTaskQueue submittingTaskQueue = requireNonNull(sequencer).latestTaskQueue;
         if (submittingTaskQueue.thread == submitting) {
           sequencer = null;
           // Submit from inside a reentrant submit. We don't know if this one will be reentrant (and
@@ -337,10 +350,12 @@ public void execute(Runnable task) {
           // execution.
           checkState(submittingTaskQueue.nextTask == null);
           submittingTaskQueue.nextTask = task;
-          submittingTaskQueue.nextExecutor = delegate;
+          // requireNonNull(delegate) is safe for reasons similar to requireNonNull(sequencer).
+          submittingTaskQueue.nextExecutor = requireNonNull(delegate);
           delegate = null;
         } else {
-          Executor localDelegate = delegate;
+          // requireNonNull(delegate) is safe for reasons similar to requireNonNull(sequencer).
+          Executor localDelegate = requireNonNull(delegate);
           delegate = null;
           this.task = task;
           localDelegate.execute(this);
@@ -359,7 +374,11 @@ public void execute(Runnable task) {
     public void run() {
       Thread currentThread = Thread.currentThread();
       if (currentThread != submitting) {
-        Runnable localTask = task;
+        /*
+         * requireNonNull is safe because we set `task` before submitting this Runnable to an
+         * Executor, and we don't null it out until here.
+         */
+        Runnable localTask = requireNonNull(task);
         task = null;
         localTask.run();
         return;
@@ -369,6 +388,18 @@ public void run() {
       // latestTaskQueue, and queue rather than calling execute() directly.
       ThreadConfinedTaskQueue executingTaskQueue = new ThreadConfinedTaskQueue();
       executingTaskQueue.thread = currentThread;
+      /*
+       * requireNonNull is safe because we don't null out `sequencer` except:
+       *
+       * - after the requireNonNull call below. (And this object has its Runnable.run override
+       *   called only once, just as it has its Executor.execute override called only once.)
+       *
+       * - if we return immediately from `execute` (in which case we never get here)
+       *
+       * - in the "reentrant submit" case of `execute` (in which case we must have started running a
+       *   user task -- which means that we already got past this code (or else we exited early
+       *   above))
+       */
       // Unconditionally set; there is no risk of throwing away a queued task from another thread,
       // because in order for the current task to run on this executor the previous task must have
       // already started execution. Because each task on a TaskNonReentrantExecutor can only produce
@@ -378,10 +409,11 @@ public void run() {
       // otherwise have another task queued on to it. Note the exception to this, cancellation, is
       // specially handled in execute() - execute() calls triggered by cancellation are no-ops, and
       // thus don't count.
-      sequencer.latestTaskQueue = executingTaskQueue;
+      requireNonNull(sequencer).latestTaskQueue = executingTaskQueue;
       sequencer = null;
       try {
-        Runnable localTask = task;
+        // requireNonNull is safe, as discussed above.
+        Runnable localTask = requireNonNull(task);
         task = null;
         localTask.run();
         // Now check if our task attempted to reentrantly execute the next task.
@@ -389,7 +421,7 @@ public void run() {
         Executor queuedExecutor;
         // Intentionally using non-short-circuit operator
         while ((queuedTask = executingTaskQueue.nextTask) != null
-            & (queuedExecutor = executingTaskQueue.nextExecutor) != null) {
+            && (queuedExecutor = executingTaskQueue.nextExecutor) != null) {
           executingTaskQueue.nextTask = null;
           executingTaskQueue.nextExecutor = null;
           queuedExecutor.execute(queuedTask);
diff --git a/guava/src/com/google/common/util/concurrent/FakeTimeLimiter.java b/guava/src/com/google/common/util/concurrent/FakeTimeLimiter.java
index 9dad51be2c8b..ddc9440188f3 100644
--- a/guava/src/com/google/common/util/concurrent/FakeTimeLimiter.java
+++ b/guava/src/com/google/common/util/concurrent/FakeTimeLimiter.java
@@ -22,6 +22,7 @@
 import java.util.concurrent.Callable;
 import java.util.concurrent.ExecutionException;
 import java.util.concurrent.TimeUnit;
+import org.checkerframework.checker.nullness.qual.Nullable;
 
 /**
  * A TimeLimiter implementation which actually does not attempt to limit time at all. This may be
@@ -36,6 +37,7 @@
 @Beta
 @CanIgnoreReturnValue
 @GwtIncompatible
+@ElementTypesAreNonnullByDefault
 public final class FakeTimeLimiter implements TimeLimiter {
   @Override
   public <T> T newProxy(
@@ -47,8 +49,9 @@ public <T> T newProxy(
   }
 
   @Override
-  public <T> T callWithTimeout(Callable<T> callable, long timeoutDuration, TimeUnit timeoutUnit)
-      throws ExecutionException {
+  @ParametricNullness
+  public <T extends @Nullable Object> T callWithTimeout(
+      Callable<T> callable, long timeoutDuration, TimeUnit timeoutUnit) throws ExecutionException {
     checkNotNull(callable);
     checkNotNull(timeoutUnit);
     try {
@@ -67,7 +70,8 @@ public <T> T callWithTimeout(Callable<T> callable, long timeoutDuration, TimeUni
   }
 
   @Override
-  public <T> T callUninterruptiblyWithTimeout(
+  @ParametricNullness
+  public <T extends @Nullable Object> T callUninterruptiblyWithTimeout(
       Callable<T> callable, long timeoutDuration, TimeUnit timeoutUnit) throws ExecutionException {
     return callWithTimeout(callable, timeoutDuration, timeoutUnit);
   }
diff --git a/guava/src/com/google/common/util/concurrent/FluentFuture.java b/guava/src/com/google/common/util/concurrent/FluentFuture.java
index 88696ea47aa8..b47e67927f08 100644
--- a/guava/src/com/google/common/util/concurrent/FluentFuture.java
+++ b/guava/src/com/google/common/util/concurrent/FluentFuture.java
@@ -29,6 +29,7 @@
 import java.util.concurrent.ScheduledExecutorService;
 import java.util.concurrent.TimeUnit;
 import java.util.concurrent.TimeoutException;
+import org.checkerframework.checker.nullness.qual.Nullable;
 
 /**
  * A {@link ListenableFuture} that supports fluent chains of operations. For example:
@@ -71,25 +72,28 @@
  *
  * @since 23.0
  */
-@Beta
 @DoNotMock("Use FluentFuture.from(Futures.immediate*Future) or SettableFuture")
 @GwtCompatible(emulated = true)
-public abstract class FluentFuture<V> extends GwtFluentFutureCatchingSpecialization<V> {
+@ElementTypesAreNonnullByDefault
+public abstract class FluentFuture<V extends @Nullable Object>
+    extends GwtFluentFutureCatchingSpecialization<V> {
 
   /**
    * A less abstract subclass of AbstractFuture. This can be used to optimize setFuture by ensuring
    * that {@link #get} calls exactly the implementation of {@link AbstractFuture#get}.
    */
-  abstract static class TrustedFuture<V> extends FluentFuture<V>
+  abstract static class TrustedFuture<V extends @Nullable Object> extends FluentFuture<V>
       implements AbstractFuture.Trusted<V> {
     @CanIgnoreReturnValue
     @Override
+    @ParametricNullness
     public final V get() throws InterruptedException, ExecutionException {
       return super.get();
     }
 
     @CanIgnoreReturnValue
     @Override
+    @ParametricNullness
     public final V get(long timeout, TimeUnit unit)
         throws InterruptedException, ExecutionException, TimeoutException {
       return super.get(timeout, unit);
@@ -126,7 +130,7 @@ public final boolean cancel(boolean mayInterruptIfRunning) {
    * directly. If not, it is wrapped in a {@code FluentFuture} that delegates all calls to the
    * original {@code ListenableFuture}.
    */
-  public static <V> FluentFuture<V> from(ListenableFuture<V> future) {
+  public static <V extends @Nullable Object> FluentFuture<V> from(ListenableFuture<V> future) {
     return future instanceof FluentFuture
         ? (FluentFuture<V>) future
         : new ForwardingFluentFuture<V>(future);
@@ -139,7 +143,7 @@ public static <V> FluentFuture<V> from(ListenableFuture<V> future) {
    * @since 28.0
    */
   @Deprecated
-  public static <V> FluentFuture<V> from(FluentFuture<V> future) {
+  public static <V extends @Nullable Object> FluentFuture<V> from(FluentFuture<V> future) {
     return checkNotNull(future);
   }
 
@@ -181,6 +185,7 @@ public static <V> FluentFuture<V> from(FluentFuture<V> future) {
    * @param executor the executor that runs {@code fallback} if the input fails
    */
   @Partially.GwtIncompatible("AVAILABLE but requires exceptionType to be Throwable.class")
+  @Beta
   public final <X extends Throwable> FluentFuture<V> catching(
       Class<X> exceptionType, Function<? super X, ? extends V> fallback, Executor executor) {
     return (FluentFuture<V>) Futures.catching(this, exceptionType, fallback, executor);
@@ -245,6 +250,7 @@ public final <X extends Throwable> FluentFuture<V> catching(
    * @param executor the executor that runs {@code fallback} if the input fails
    */
   @Partially.GwtIncompatible("AVAILABLE but requires exceptionType to be Throwable.class")
+  @Beta
   public final <X extends Throwable> FluentFuture<V> catchingAsync(
       Class<X> exceptionType, AsyncFunction<? super X, ? extends V> fallback, Executor executor) {
     return (FluentFuture<V>) Futures.catchingAsync(this, exceptionType, fallback, executor);
@@ -261,6 +267,7 @@ public final <X extends Throwable> FluentFuture<V> catchingAsync(
    * @since 28.0
    */
   @GwtIncompatible // ScheduledExecutorService
+  @Beta
   public final FluentFuture<V> withTimeout(
       Duration timeout, ScheduledExecutorService scheduledExecutor) {
     return withTimeout(toNanosSaturated(timeout), TimeUnit.NANOSECONDS, scheduledExecutor);
@@ -278,6 +285,7 @@ public final FluentFuture<V> withTimeout(
    */
   @GwtIncompatible // ScheduledExecutorService
   @SuppressWarnings("GoodTime") // should accept a java.time.Duration
+  @Beta
   public final FluentFuture<V> withTimeout(
       long timeout, TimeUnit unit, ScheduledExecutorService scheduledExecutor) {
     return (FluentFuture<V>) Futures.withTimeout(this, timeout, unit, scheduledExecutor);
@@ -322,7 +330,8 @@ public final FluentFuture<V> withTimeout(
    * @return A future that holds result of the function (if the input succeeded) or the original
    *     input's failure (if not)
    */
-  public final <T> FluentFuture<T> transformAsync(
+  @Beta
+  public final <T extends @Nullable Object> FluentFuture<T> transformAsync(
       AsyncFunction<? super V, T> function, Executor executor) {
     return (FluentFuture<T>) Futures.transformAsync(this, function, executor);
   }
@@ -359,7 +368,9 @@ public final <T> FluentFuture<T> transformAsync(
    * @param executor Executor to run the function in.
    * @return A future that holds result of the transformation.
    */
-  public final <T> FluentFuture<T> transform(Function<? super V, T> function, Executor executor) {
+  @Beta
+  public final <T extends @Nullable Object> FluentFuture<T> transform(
+      Function<? super V, T> function, Executor executor) {
     return (FluentFuture<T>) Futures.transform(this, function, executor);
   }
 
diff --git a/guava/src/com/google/common/util/concurrent/ForwardingBlockingDeque.java b/guava/src/com/google/common/util/concurrent/ForwardingBlockingDeque.java
index 2485966948de..d0d72a815918 100644
--- a/guava/src/com/google/common/util/concurrent/ForwardingBlockingDeque.java
+++ b/guava/src/com/google/common/util/concurrent/ForwardingBlockingDeque.java
@@ -21,6 +21,7 @@
 import java.util.Collection;
 import java.util.concurrent.BlockingDeque;
 import java.util.concurrent.TimeUnit;
+import javax.annotation.CheckForNull;
 
 /**
  * A {@link BlockingDeque} which forwards all its method calls to another {@code BlockingDeque}.
@@ -44,6 +45,7 @@
  * @since 21.0 (since 14.0 as {@link com.google.common.collect.ForwardingBlockingDeque})
  */
 @GwtIncompatible
+@ElementTypesAreNonnullByDefault
 public abstract class ForwardingBlockingDeque<E> extends ForwardingDeque<E>
     implements BlockingDeque<E> {
 
@@ -89,11 +91,13 @@ public E takeLast() throws InterruptedException {
   }
 
   @Override
+  @CheckForNull
   public E pollFirst(long timeout, TimeUnit unit) throws InterruptedException {
     return delegate().pollFirst(timeout, unit);
   }
 
   @Override
+  @CheckForNull
   public E pollLast(long timeout, TimeUnit unit) throws InterruptedException {
     return delegate().pollLast(timeout, unit);
   }
@@ -114,6 +118,7 @@ public E take() throws InterruptedException {
   }
 
   @Override
+  @CheckForNull
   public E poll(long timeout, TimeUnit unit) throws InterruptedException {
     return delegate().poll(timeout, unit);
   }
diff --git a/guava/src/com/google/common/util/concurrent/ForwardingBlockingQueue.java b/guava/src/com/google/common/util/concurrent/ForwardingBlockingQueue.java
index f5575a15767c..dc8511d94c7c 100644
--- a/guava/src/com/google/common/util/concurrent/ForwardingBlockingQueue.java
+++ b/guava/src/com/google/common/util/concurrent/ForwardingBlockingQueue.java
@@ -20,6 +20,7 @@
 import java.util.Collection;
 import java.util.concurrent.BlockingQueue;
 import java.util.concurrent.TimeUnit;
+import javax.annotation.CheckForNull;
 
 /**
  * A {@link BlockingQueue} which forwards all its method calls to another {@link BlockingQueue}.
@@ -37,6 +38,7 @@
  */
 @CanIgnoreReturnValue // TODO(cpovirk): Consider being more strict.
 @GwtIncompatible
+@ElementTypesAreNonnullByDefault
 public abstract class ForwardingBlockingQueue<E> extends ForwardingQueue<E>
     implements BlockingQueue<E> {
 
@@ -62,6 +64,7 @@ public boolean offer(E e, long timeout, TimeUnit unit) throws InterruptedExcepti
   }
 
   @Override
+  @CheckForNull
   public E poll(long timeout, TimeUnit unit) throws InterruptedException {
     return delegate().poll(timeout, unit);
   }
diff --git a/guava/src/com/google/common/util/concurrent/ForwardingCondition.java b/guava/src/com/google/common/util/concurrent/ForwardingCondition.java
index 62c4d4c37843..d17f98cf2aa1 100644
--- a/guava/src/com/google/common/util/concurrent/ForwardingCondition.java
+++ b/guava/src/com/google/common/util/concurrent/ForwardingCondition.java
@@ -19,6 +19,7 @@
 import java.util.concurrent.locks.Condition;
 
 /** Forwarding wrapper around a {@code Condition}. */
+@ElementTypesAreNonnullByDefault
 abstract class ForwardingCondition implements Condition {
   abstract Condition delegate();
 
diff --git a/guava/src/com/google/common/util/concurrent/ForwardingExecutorService.java b/guava/src/com/google/common/util/concurrent/ForwardingExecutorService.java
index f9da1d495631..ed78b8685694 100644
--- a/guava/src/com/google/common/util/concurrent/ForwardingExecutorService.java
+++ b/guava/src/com/google/common/util/concurrent/ForwardingExecutorService.java
@@ -25,6 +25,7 @@
 import java.util.concurrent.Future;
 import java.util.concurrent.TimeUnit;
 import java.util.concurrent.TimeoutException;
+import org.checkerframework.checker.nullness.qual.Nullable;
 
 /**
  * An executor service which forwards all its method calls to another executor service. Subclasses
@@ -36,6 +37,7 @@
  */
 @CanIgnoreReturnValue // TODO(cpovirk): Consider being more strict.
 @GwtIncompatible
+@ElementTypesAreNonnullByDefault
 public abstract class ForwardingExecutorService extends ForwardingObject
     implements ExecutorService {
   /** Constructor for use by subclasses. */
@@ -50,26 +52,27 @@ public boolean awaitTermination(long timeout, TimeUnit unit) throws InterruptedE
   }
 
   @Override
-  public <T> List<Future<T>> invokeAll(Collection<? extends Callable<T>> tasks)
-      throws InterruptedException {
+  public <T extends @Nullable Object> List<Future<T>> invokeAll(
+      Collection<? extends Callable<T>> tasks) throws InterruptedException {
     return delegate().invokeAll(tasks);
   }
 
   @Override
-  public <T> List<Future<T>> invokeAll(
+  public <T extends @Nullable Object> List<Future<T>> invokeAll(
       Collection<? extends Callable<T>> tasks, long timeout, TimeUnit unit)
       throws InterruptedException {
     return delegate().invokeAll(tasks, timeout, unit);
   }
 
   @Override
-  public <T> T invokeAny(Collection<? extends Callable<T>> tasks)
+  public <T extends @Nullable Object> T invokeAny(Collection<? extends Callable<T>> tasks)
       throws InterruptedException, ExecutionException {
     return delegate().invokeAny(tasks);
   }
 
   @Override
-  public <T> T invokeAny(Collection<? extends Callable<T>> tasks, long timeout, TimeUnit unit)
+  public <T extends @Nullable Object> T invokeAny(
+      Collection<? extends Callable<T>> tasks, long timeout, TimeUnit unit)
       throws InterruptedException, ExecutionException, TimeoutException {
     return delegate().invokeAny(tasks, timeout, unit);
   }
@@ -100,7 +103,7 @@ public void execute(Runnable command) {
   }
 
   @Override
-  public <T> Future<T> submit(Callable<T> task) {
+  public <T extends @Nullable Object> Future<T> submit(Callable<T> task) {
     return delegate().submit(task);
   }
 
@@ -110,7 +113,8 @@ public Future<?> submit(Runnable task) {
   }
 
   @Override
-  public <T> Future<T> submit(Runnable task, T result) {
+  public <T extends @Nullable Object> Future<T> submit(
+      Runnable task, @ParametricNullness T result) {
     return delegate().submit(task, result);
   }
 }
diff --git a/guava/src/com/google/common/util/concurrent/ForwardingFluentFuture.java b/guava/src/com/google/common/util/concurrent/ForwardingFluentFuture.java
index 984fd680162d..cb779c34ed4b 100644
--- a/guava/src/com/google/common/util/concurrent/ForwardingFluentFuture.java
+++ b/guava/src/com/google/common/util/concurrent/ForwardingFluentFuture.java
@@ -21,6 +21,7 @@
 import java.util.concurrent.Executor;
 import java.util.concurrent.TimeUnit;
 import java.util.concurrent.TimeoutException;
+import org.checkerframework.checker.nullness.qual.Nullable;
 
 /**
  * {@link FluentFuture} that forwards all calls to a delegate.
@@ -33,7 +34,8 @@
  * forwards to that future and adds the desired methods.
  */
 @GwtCompatible
-final class ForwardingFluentFuture<V> extends FluentFuture<V> {
+@ElementTypesAreNonnullByDefault
+final class ForwardingFluentFuture<V extends @Nullable Object> extends FluentFuture<V> {
   private final ListenableFuture<V> delegate;
 
   ForwardingFluentFuture(ListenableFuture<V> delegate) {
@@ -61,11 +63,13 @@ public boolean isDone() {
   }
 
   @Override
+  @ParametricNullness
   public V get() throws InterruptedException, ExecutionException {
     return delegate.get();
   }
 
   @Override
+  @ParametricNullness
   public V get(long timeout, TimeUnit unit)
       throws InterruptedException, ExecutionException, TimeoutException {
     return delegate.get(timeout, unit);
diff --git a/guava/src/com/google/common/util/concurrent/ForwardingFuture.java b/guava/src/com/google/common/util/concurrent/ForwardingFuture.java
index 165793bef25c..47002b03a31b 100644
--- a/guava/src/com/google/common/util/concurrent/ForwardingFuture.java
+++ b/guava/src/com/google/common/util/concurrent/ForwardingFuture.java
@@ -22,6 +22,7 @@
 import java.util.concurrent.Future;
 import java.util.concurrent.TimeUnit;
 import java.util.concurrent.TimeoutException;
+import org.checkerframework.checker.nullness.qual.Nullable;
 
 /**
  * A {@link Future} which forwards all its method calls to another future. Subclasses should
@@ -35,7 +36,9 @@
  */
 @CanIgnoreReturnValue // TODO(cpovirk): Consider being more strict.
 @GwtCompatible
-public abstract class ForwardingFuture<V> extends ForwardingObject implements Future<V> {
+@ElementTypesAreNonnullByDefault
+public abstract class ForwardingFuture<V extends @Nullable Object> extends ForwardingObject
+    implements Future<V> {
   /** Constructor for use by subclasses. */
   protected ForwardingFuture() {}
 
@@ -58,11 +61,13 @@ public boolean isDone() {
   }
 
   @Override
+  @ParametricNullness
   public V get() throws InterruptedException, ExecutionException {
     return delegate().get();
   }
 
   @Override
+  @ParametricNullness
   public V get(long timeout, TimeUnit unit)
       throws InterruptedException, ExecutionException, TimeoutException {
     return delegate().get(timeout, unit);
@@ -75,7 +80,8 @@ public V get(long timeout, TimeUnit unit)
    *
    * @since 9.0
    */
-  public abstract static class SimpleForwardingFuture<V> extends ForwardingFuture<V> {
+  public abstract static class SimpleForwardingFuture<V extends @Nullable Object>
+      extends ForwardingFuture<V> {
     private final Future<V> delegate;
 
     protected SimpleForwardingFuture(Future<V> delegate) {
diff --git a/guava/src/com/google/common/util/concurrent/ForwardingListenableFuture.java b/guava/src/com/google/common/util/concurrent/ForwardingListenableFuture.java
index d3ed3c28a89b..386809194b84 100644
--- a/guava/src/com/google/common/util/concurrent/ForwardingListenableFuture.java
+++ b/guava/src/com/google/common/util/concurrent/ForwardingListenableFuture.java
@@ -18,6 +18,7 @@
 import com.google.common.base.Preconditions;
 import com.google.errorprone.annotations.CanIgnoreReturnValue;
 import java.util.concurrent.Executor;
+import org.checkerframework.checker.nullness.qual.Nullable;
 
 /**
  * A {@link ListenableFuture} which forwards all its method calls to another future. Subclasses
@@ -31,8 +32,9 @@
  */
 @CanIgnoreReturnValue // TODO(cpovirk): Consider being more strict.
 @GwtCompatible
-public abstract class ForwardingListenableFuture<V> extends ForwardingFuture<V>
-    implements ListenableFuture<V> {
+@ElementTypesAreNonnullByDefault
+public abstract class ForwardingListenableFuture<V extends @Nullable Object>
+    extends ForwardingFuture<V> implements ListenableFuture<V> {
 
   /** Constructor for use by subclasses. */
   protected ForwardingListenableFuture() {}
@@ -52,7 +54,7 @@ public void addListener(Runnable listener, Executor exec) {
    *
    * @since 9.0
    */
-  public abstract static class SimpleForwardingListenableFuture<V>
+  public abstract static class SimpleForwardingListenableFuture<V extends @Nullable Object>
       extends ForwardingListenableFuture<V> {
     private final ListenableFuture<V> delegate;
 
diff --git a/guava/src/com/google/common/util/concurrent/ForwardingListeningExecutorService.java b/guava/src/com/google/common/util/concurrent/ForwardingListeningExecutorService.java
index 48a49b89d83c..fe25b867af4c 100644
--- a/guava/src/com/google/common/util/concurrent/ForwardingListeningExecutorService.java
+++ b/guava/src/com/google/common/util/concurrent/ForwardingListeningExecutorService.java
@@ -17,6 +17,7 @@
 import com.google.common.annotations.GwtIncompatible;
 import com.google.errorprone.annotations.CanIgnoreReturnValue;
 import java.util.concurrent.Callable;
+import org.checkerframework.checker.nullness.qual.Nullable;
 
 /**
  * A listening executor service which forwards all its method calls to another listening executor
@@ -29,6 +30,7 @@
  */
 @CanIgnoreReturnValue // TODO(cpovirk): Consider being more strict.
 @GwtIncompatible
+@ElementTypesAreNonnullByDefault
 public abstract class ForwardingListeningExecutorService extends ForwardingExecutorService
     implements ListeningExecutorService {
   /** Constructor for use by subclasses. */
@@ -38,7 +40,7 @@ protected ForwardingListeningExecutorService() {}
   protected abstract ListeningExecutorService delegate();
 
   @Override
-  public <T> ListenableFuture<T> submit(Callable<T> task) {
+  public <T extends @Nullable Object> ListenableFuture<T> submit(Callable<T> task) {
     return delegate().submit(task);
   }
 
@@ -48,7 +50,8 @@ public ListenableFuture<?> submit(Runnable task) {
   }
 
   @Override
-  public <T> ListenableFuture<T> submit(Runnable task, T result) {
+  public <T extends @Nullable Object> ListenableFuture<T> submit(
+      Runnable task, @ParametricNullness T result) {
     return delegate().submit(task, result);
   }
 }
diff --git a/guava/src/com/google/common/util/concurrent/ForwardingLock.java b/guava/src/com/google/common/util/concurrent/ForwardingLock.java
index 8c50787ba8b6..db2026ab414c 100644
--- a/guava/src/com/google/common/util/concurrent/ForwardingLock.java
+++ b/guava/src/com/google/common/util/concurrent/ForwardingLock.java
@@ -19,6 +19,7 @@
 import java.util.concurrent.locks.Lock;
 
 /** Forwarding wrapper around a {@code Lock}. */
+@ElementTypesAreNonnullByDefault
 abstract class ForwardingLock implements Lock {
   abstract Lock delegate();
 
diff --git a/guava/src/com/google/common/util/concurrent/FutureCallback.java b/guava/src/com/google/common/util/concurrent/FutureCallback.java
index b18047751469..f5684e7c907a 100644
--- a/guava/src/com/google/common/util/concurrent/FutureCallback.java
+++ b/guava/src/com/google/common/util/concurrent/FutureCallback.java
@@ -29,9 +29,10 @@
  * @since 10.0
  */
 @GwtCompatible
-public interface FutureCallback<V> {
+@ElementTypesAreNonnullByDefault
+public interface FutureCallback<V extends @Nullable Object> {
   /** Invoked with the result of the {@code Future} computation when it is successful. */
-  void onSuccess(@Nullable V result);
+  void onSuccess(@ParametricNullness V result);
 
   /**
    * Invoked when a {@code Future} computation fails or is canceled.
diff --git a/guava/src/com/google/common/util/concurrent/Futures.java b/guava/src/com/google/common/util/concurrent/Futures.java
index c06899619aac..09b5c3c1a426 100644
--- a/guava/src/com/google/common/util/concurrent/Futures.java
+++ b/guava/src/com/google/common/util/concurrent/Futures.java
@@ -19,6 +19,7 @@
 import static com.google.common.util.concurrent.Internal.toNanosSaturated;
 import static com.google.common.util.concurrent.MoreExecutors.directExecutor;
 import static com.google.common.util.concurrent.Uninterruptibles.getUninterruptibly;
+import static java.util.Objects.requireNonNull;
 
 import com.google.common.annotations.Beta;
 import com.google.common.annotations.GwtCompatible;
@@ -46,6 +47,7 @@
 import java.util.concurrent.TimeUnit;
 import java.util.concurrent.TimeoutException;
 import java.util.concurrent.atomic.AtomicInteger;
+import javax.annotation.CheckForNull;
 import org.checkerframework.checker.nullness.qual.Nullable;
 
 /**
@@ -73,6 +75,7 @@
  * @since 1.0
  */
 @GwtCompatible(emulated = true)
+@ElementTypesAreNonnullByDefault
 public final class Futures extends GwtFuturesCatchingSpecialization {
 
   // A note on memory visibility.
@@ -127,7 +130,8 @@ private Futures() {}
    * getters just return the value. This {@code Future} can't be canceled or timed out and its
    * {@code isDone()} method always returns {@code true}.
    */
-  public static <V> ListenableFuture<V> immediateFuture(@Nullable V value) {
+  public static <V extends @Nullable Object> ListenableFuture<V> immediateFuture(
+      @ParametricNullness V value) {
     if (value == null) {
       // This cast is safe because null is assignable to V for all V (i.e. it is bivariant)
       @SuppressWarnings("unchecked")
@@ -144,8 +148,8 @@ public static <V> ListenableFuture<V> immediateFuture(@Nullable V value) {
    * @since 29.0
    */
   @SuppressWarnings("unchecked")
-  public static ListenableFuture<Void> immediateVoidFuture() {
-    return (ListenableFuture<Void>) ImmediateFuture.NULL;
+  public static ListenableFuture<@Nullable Void> immediateVoidFuture() {
+    return (ListenableFuture<@Nullable Void>) ImmediateFuture.NULL;
   }
 
   /**
@@ -155,7 +159,8 @@ public static ListenableFuture<Void> immediateVoidFuture() {
    * returns {@code true}. Calling {@code get()} will immediately throw the provided {@code
    * Throwable} wrapped in an {@code ExecutionException}.
    */
-  public static <V> ListenableFuture<V> immediateFailedFuture(Throwable throwable) {
+  public static <V extends @Nullable Object> ListenableFuture<V> immediateFailedFuture(
+      Throwable throwable) {
     checkNotNull(throwable);
     return new ImmediateFailedFuture<V>(throwable);
   }
@@ -166,8 +171,12 @@ public static <V> ListenableFuture<V> immediateFailedFuture(Throwable throwable)
    *
    * @since 14.0
    */
-  public static <V> ListenableFuture<V> immediateCancelledFuture() {
-    return new ImmediateCancelledFuture<V>();
+  public static <V extends @Nullable Object> ListenableFuture<V> immediateCancelledFuture() {
+    ListenableFuture<Object> instance = ImmediateCancelledFuture.INSTANCE;
+    if (instance != null) {
+      return (ListenableFuture<V>) instance;
+    }
+    return new ImmediateCancelledFuture<>();
   }
 
   /**
@@ -176,8 +185,8 @@ public static <V> ListenableFuture<V> immediateCancelledFuture() {
    * @throws RejectedExecutionException if the task cannot be scheduled for execution
    * @since 28.2
    */
-  @Beta
-  public static <O> ListenableFuture<O> submit(Callable<O> callable, Executor executor) {
+  public static <O extends @Nullable Object> ListenableFuture<O> submit(
+      Callable<O> callable, Executor executor) {
     TrustedListenableFutureTask<O> task = TrustedListenableFutureTask.create(callable);
     executor.execute(task);
     return task;
@@ -190,9 +199,9 @@ public static <O> ListenableFuture<O> submit(Callable<O> callable, Executor exec
    * @throws RejectedExecutionException if the task cannot be scheduled for execution
    * @since 28.2
    */
-  @Beta
-  public static ListenableFuture<Void> submit(Runnable runnable, Executor executor) {
-    TrustedListenableFutureTask<Void> task = TrustedListenableFutureTask.create(runnable, null);
+  public static ListenableFuture<@Nullable Void> submit(Runnable runnable, Executor executor) {
+    TrustedListenableFutureTask<@Nullable Void> task =
+        TrustedListenableFutureTask.create(runnable, null);
     executor.execute(task);
     return task;
   }
@@ -203,8 +212,8 @@ public static ListenableFuture<Void> submit(Runnable runnable, Executor executor
    * @throws RejectedExecutionException if the task cannot be scheduled for execution
    * @since 23.0
    */
-  @Beta
-  public static <O> ListenableFuture<O> submitAsync(AsyncCallable<O> callable, Executor executor) {
+  public static <O extends @Nullable Object> ListenableFuture<O> submitAsync(
+      AsyncCallable<O> callable, Executor executor) {
     TrustedListenableFutureTask<O> task = TrustedListenableFutureTask.create(callable);
     executor.execute(task);
     return task;
@@ -216,9 +225,9 @@ public static <O> ListenableFuture<O> submitAsync(AsyncCallable<O> callable, Exe
    * @throws RejectedExecutionException if the task cannot be scheduled for execution
    * @since 28.0
    */
-  @Beta
   @GwtIncompatible // java.util.concurrent.ScheduledExecutorService
-  public static <O> ListenableFuture<O> scheduleAsync(
+  // TODO(cpovirk): Return ListenableScheduledFuture?
+  public static <O extends @Nullable Object> ListenableFuture<O> scheduleAsync(
       AsyncCallable<O> callable, Duration delay, ScheduledExecutorService executorService) {
     return scheduleAsync(callable, toNanosSaturated(delay), TimeUnit.NANOSECONDS, executorService);
   }
@@ -229,10 +238,10 @@ public static <O> ListenableFuture<O> scheduleAsync(
    * @throws RejectedExecutionException if the task cannot be scheduled for execution
    * @since 23.0
    */
-  @Beta
   @GwtIncompatible // java.util.concurrent.ScheduledExecutorService
   @SuppressWarnings("GoodTime") // should accept a java.time.Duration
-  public static <O> ListenableFuture<O> scheduleAsync(
+  // TODO(cpovirk): Return ListenableScheduledFuture?
+  public static <O extends @Nullable Object> ListenableFuture<O> scheduleAsync(
       AsyncCallable<O> callable,
       long delay,
       TimeUnit timeUnit,
@@ -289,7 +298,7 @@ public void run() {
    */
   @Beta
   @Partially.GwtIncompatible("AVAILABLE but requires exceptionType to be Throwable.class")
-  public static <V, X extends Throwable> ListenableFuture<V> catching(
+  public static <V extends @Nullable Object, X extends Throwable> ListenableFuture<V> catching(
       ListenableFuture<? extends V> input,
       Class<X> exceptionType,
       Function<? super X, ? extends V> fallback,
@@ -354,7 +363,7 @@ public static <V, X extends Throwable> ListenableFuture<V> catching(
    */
   @Beta
   @Partially.GwtIncompatible("AVAILABLE but requires exceptionType to be Throwable.class")
-  public static <V, X extends Throwable> ListenableFuture<V> catchingAsync(
+  public static <V extends @Nullable Object, X extends Throwable> ListenableFuture<V> catchingAsync(
       ListenableFuture<? extends V> input,
       Class<X> exceptionType,
       AsyncFunction<? super X, ? extends V> fallback,
@@ -375,7 +384,7 @@ public static <V, X extends Throwable> ListenableFuture<V> catchingAsync(
    */
   @Beta
   @GwtIncompatible // java.util.concurrent.ScheduledExecutorService
-  public static <V> ListenableFuture<V> withTimeout(
+  public static <V extends @Nullable Object> ListenableFuture<V> withTimeout(
       ListenableFuture<V> delegate, Duration time, ScheduledExecutorService scheduledExecutor) {
     return withTimeout(delegate, toNanosSaturated(time), TimeUnit.NANOSECONDS, scheduledExecutor);
   }
@@ -395,7 +404,7 @@ public static <V> ListenableFuture<V> withTimeout(
   @Beta
   @GwtIncompatible // java.util.concurrent.ScheduledExecutorService
   @SuppressWarnings("GoodTime") // should accept a java.time.Duration
-  public static <V> ListenableFuture<V> withTimeout(
+  public static <V extends @Nullable Object> ListenableFuture<V> withTimeout(
       ListenableFuture<V> delegate,
       long time,
       TimeUnit unit,
@@ -439,10 +448,11 @@ public static <V> ListenableFuture<V> withTimeout(
    * @since 19.0 (in 11.0 as {@code transform})
    */
   @Beta
-  public static <I, O> ListenableFuture<O> transformAsync(
-      ListenableFuture<I> input,
-      AsyncFunction<? super I, ? extends O> function,
-      Executor executor) {
+  public static <I extends @Nullable Object, O extends @Nullable Object>
+      ListenableFuture<O> transformAsync(
+          ListenableFuture<I> input,
+          AsyncFunction<? super I, ? extends O> function,
+          Executor executor) {
     return AbstractTransformFuture.create(input, function, executor);
   }
 
@@ -476,8 +486,9 @@ public static <I, O> ListenableFuture<O> transformAsync(
    * @since 9.0 (in 2.0 as {@code compose})
    */
   @Beta
-  public static <I, O> ListenableFuture<O> transform(
-      ListenableFuture<I> input, Function<? super I, ? extends O> function, Executor executor) {
+  public static <I extends @Nullable Object, O extends @Nullable Object>
+      ListenableFuture<O> transform(
+          ListenableFuture<I> input, Function<? super I, ? extends O> function, Executor executor) {
     return AbstractTransformFuture.create(input, function, executor);
   }
 
@@ -503,7 +514,7 @@ public static <I, O> ListenableFuture<O> transform(
    */
   @Beta
   @GwtIncompatible // TODO
-  public static <I, O> Future<O> lazyTransform(
+  public static <I extends @Nullable Object, O extends @Nullable Object> Future<O> lazyTransform(
       final Future<I> input, final Function<? super I, ? extends O> function) {
     checkNotNull(input);
     checkNotNull(function);
@@ -563,8 +574,14 @@ private O applyTransformation(I input) throws ExecutionException {
    */
   @Beta
   @SafeVarargs
-  public static <V> ListenableFuture<List<V>> allAsList(ListenableFuture<? extends V>... futures) {
-    return new ListFuture<V>(ImmutableList.copyOf(futures), true);
+  public static <V extends @Nullable Object> ListenableFuture<List<V>> allAsList(
+      ListenableFuture<? extends V>... futures) {
+    ListenableFuture<List<@Nullable V>> nullable =
+        new ListFuture<V>(ImmutableList.copyOf(futures), true);
+    // allAsList ensures that it fills the output list with V instances.
+    @SuppressWarnings("nullness")
+    ListenableFuture<List<V>> nonNull = nullable;
+    return nonNull;
   }
 
   /**
@@ -584,9 +601,14 @@ public static <V> ListenableFuture<List<V>> allAsList(ListenableFuture<? extends
    * @since 10.0
    */
   @Beta
-  public static <V> ListenableFuture<List<V>> allAsList(
+  public static <V extends @Nullable Object> ListenableFuture<List<V>> allAsList(
       Iterable<? extends ListenableFuture<? extends V>> futures) {
-    return new ListFuture<V>(ImmutableList.copyOf(futures), true);
+    ListenableFuture<List<@Nullable V>> nullable =
+        new ListFuture<V>(ImmutableList.copyOf(futures), true);
+    // allAsList ensures that it fills the output list with V instances.
+    @SuppressWarnings("nullness")
+    ListenableFuture<List<V>> nonNull = nullable;
+    return nonNull;
   }
 
   /**
@@ -599,7 +621,8 @@ public static <V> ListenableFuture<List<V>> allAsList(
    */
   @Beta
   @SafeVarargs
-  public static <V> FutureCombiner<V> whenAllComplete(ListenableFuture<? extends V>... futures) {
+  public static <V extends @Nullable Object> FutureCombiner<V> whenAllComplete(
+      ListenableFuture<? extends V>... futures) {
     return new FutureCombiner<V>(false, ImmutableList.copyOf(futures));
   }
 
@@ -612,7 +635,7 @@ public static <V> FutureCombiner<V> whenAllComplete(ListenableFuture<? extends V
    * @since 20.0
    */
   @Beta
-  public static <V> FutureCombiner<V> whenAllComplete(
+  public static <V extends @Nullable Object> FutureCombiner<V> whenAllComplete(
       Iterable<? extends ListenableFuture<? extends V>> futures) {
     return new FutureCombiner<V>(false, ImmutableList.copyOf(futures));
   }
@@ -626,7 +649,8 @@ public static <V> FutureCombiner<V> whenAllComplete(
    */
   @Beta
   @SafeVarargs
-  public static <V> FutureCombiner<V> whenAllSucceed(ListenableFuture<? extends V>... futures) {
+  public static <V extends @Nullable Object> FutureCombiner<V> whenAllSucceed(
+      ListenableFuture<? extends V>... futures) {
     return new FutureCombiner<V>(true, ImmutableList.copyOf(futures));
   }
 
@@ -638,7 +662,7 @@ public static <V> FutureCombiner<V> whenAllSucceed(ListenableFuture<? extends V>
    * @since 20.0
    */
   @Beta
-  public static <V> FutureCombiner<V> whenAllSucceed(
+  public static <V extends @Nullable Object> FutureCombiner<V> whenAllSucceed(
       Iterable<? extends ListenableFuture<? extends V>> futures) {
     return new FutureCombiner<V>(true, ImmutableList.copyOf(futures));
   }
@@ -672,7 +696,7 @@ public static <V> FutureCombiner<V> whenAllSucceed(
   @Beta
   @CanIgnoreReturnValue // TODO(cpovirk): Consider removing, especially if we provide run(Runnable)
   @GwtCompatible
-  public static final class FutureCombiner<V> {
+  public static final class FutureCombiner<V extends @Nullable Object> {
     private final boolean allMustSucceed;
     private final ImmutableList<ListenableFuture<? extends V>> futures;
 
@@ -696,7 +720,8 @@ private FutureCombiner(
      *
      * <p>Canceling this future will attempt to cancel all the component futures.
      */
-    public <C> ListenableFuture<C> callAsync(AsyncCallable<C> combiner, Executor executor) {
+    public <C extends @Nullable Object> ListenableFuture<C> callAsync(
+        AsyncCallable<C> combiner, Executor executor) {
       return new CombinedFuture<C>(futures, allMustSucceed, executor, combiner);
     }
 
@@ -715,7 +740,8 @@ public <C> ListenableFuture<C> callAsync(AsyncCallable<C> combiner, Executor exe
      * <p>Canceling this future will attempt to cancel all the component futures.
      */
     @CanIgnoreReturnValue // TODO(cpovirk): Remove this
-    public <C> ListenableFuture<C> call(Callable<C> combiner, Executor executor) {
+    public <C extends @Nullable Object> ListenableFuture<C> call(
+        Callable<C> combiner, Executor executor) {
       return new CombinedFuture<C>(futures, allMustSucceed, executor, combiner);
     }
 
@@ -732,8 +758,9 @@ public <C> ListenableFuture<C> call(Callable<C> combiner, Executor executor) {
      */
     public ListenableFuture<?> run(final Runnable combiner, Executor executor) {
       return call(
-          new Callable<Void>() {
+          new Callable<@Nullable Void>() {
             @Override
+            @CheckForNull
             public Void call() throws Exception {
               combiner.run();
               return null;
@@ -750,8 +777,8 @@ public Void call() throws Exception {
    *
    * @since 15.0
    */
-  @Beta
-  public static <V> ListenableFuture<V> nonCancellationPropagating(ListenableFuture<V> future) {
+  public static <V extends @Nullable Object> ListenableFuture<V> nonCancellationPropagating(
+      ListenableFuture<V> future) {
     if (future.isDone()) {
       return future;
     }
@@ -761,9 +788,9 @@ public static <V> ListenableFuture<V> nonCancellationPropagating(ListenableFutur
   }
 
   /** A wrapped future that does not propagate cancellation to its delegate. */
-  private static final class NonCancellationPropagatingFuture<V>
+  private static final class NonCancellationPropagatingFuture<V extends @Nullable Object>
       extends AbstractFuture.TrustedFuture<V> implements Runnable {
-    private ListenableFuture<V> delegate;
+    @CheckForNull private ListenableFuture<V> delegate;
 
     NonCancellationPropagatingFuture(final ListenableFuture<V> delegate) {
       this.delegate = delegate;
@@ -780,6 +807,7 @@ public void run() {
     }
 
     @Override
+    @CheckForNull
     protected String pendingToString() {
       ListenableFuture<V> localDelegate = delegate;
       if (localDelegate != null) {
@@ -814,8 +842,20 @@ protected void afterDone() {
    */
   @Beta
   @SafeVarargs
-  public static <V> ListenableFuture<List<V>> successfulAsList(
+  public static <V extends @Nullable Object> ListenableFuture<List<@Nullable V>> successfulAsList(
       ListenableFuture<? extends V>... futures) {
+    /*
+     * Another way to express this signature would be to bound <V> by @NonNull and accept
+     * LF<? extends @Nullable V>. That might be better: There's currently no difference between the
+     * outputs users get when calling this with <Foo> and calling it with <@Nullable Foo>. The only
+     * difference is that calling it with <Foo> won't work when an input Future has a @Nullable
+     * type. So why even make that error possible by giving callers the choice?
+     *
+     * On the other hand, the current signature is consistent with the similar allAsList method. And
+     * eventually this method may go away entirely in favor of an API like
+     * whenAllComplete().collectSuccesses(). That API would have a signature more like the current
+     * one.
+     */
     return new ListFuture<V>(ImmutableList.copyOf(futures), false);
   }
 
@@ -838,7 +878,7 @@ public static <V> ListenableFuture<List<V>> successfulAsList(
    * @since 10.0
    */
   @Beta
-  public static <V> ListenableFuture<List<V>> successfulAsList(
+  public static <V extends @Nullable Object> ListenableFuture<List<@Nullable V>> successfulAsList(
       Iterable<? extends ListenableFuture<? extends V>> futures) {
     return new ListFuture<V>(ImmutableList.copyOf(futures), false);
   }
@@ -864,22 +904,12 @@ public static <V> ListenableFuture<List<V>> successfulAsList(
    *
    * @since 17.0
    */
-  @Beta
-  public static <T> ImmutableList<ListenableFuture<T>> inCompletionOrder(
+  public static <T extends @Nullable Object> ImmutableList<ListenableFuture<T>> inCompletionOrder(
       Iterable<? extends ListenableFuture<? extends T>> futures) {
-    // Can't use Iterables.toArray because it's not gwt compatible
-    final Collection<ListenableFuture<? extends T>> collection;
-    if (futures instanceof Collection) {
-      collection = (Collection<ListenableFuture<? extends T>>) futures;
-    } else {
-      collection = ImmutableList.copyOf(futures);
-    }
-    @SuppressWarnings("unchecked")
-    ListenableFuture<? extends T>[] copy =
-        (ListenableFuture<? extends T>[])
-            collection.toArray(new ListenableFuture[collection.size()]);
+    ListenableFuture<? extends T>[] copy = gwtCompatibleToArray(futures);
     final InCompletionOrderState<T> state = new InCompletionOrderState<>(copy);
-    ImmutableList.Builder<AbstractFuture<T>> delegatesBuilder = ImmutableList.builder();
+    ImmutableList.Builder<AbstractFuture<T>> delegatesBuilder =
+        ImmutableList.builderWithExpectedSize(copy.length);
     for (int i = 0; i < copy.length; i++) {
       delegatesBuilder.add(new InCompletionOrderFuture<T>(state));
     }
@@ -902,11 +932,25 @@ public void run() {
     return delegatesCast;
   }
 
+  /** Can't use Iterables.toArray because it's not gwt compatible */
+  @SuppressWarnings("unchecked")
+  private static <T extends @Nullable Object> ListenableFuture<? extends T>[] gwtCompatibleToArray(
+      Iterable<? extends ListenableFuture<? extends T>> futures) {
+    final Collection<ListenableFuture<? extends T>> collection;
+    if (futures instanceof Collection) {
+      collection = (Collection<ListenableFuture<? extends T>>) futures;
+    } else {
+      collection = ImmutableList.copyOf(futures);
+    }
+    return (ListenableFuture<? extends T>[]) collection.toArray(new ListenableFuture<?>[0]);
+  }
+
   // This can't be a TrustedFuture, because TrustedFuture has clever optimizations that
   // mean cancel won't be called if this Future is passed into setFuture, and then
   // cancelled.
-  private static final class InCompletionOrderFuture<T> extends AbstractFuture<T> {
-    private InCompletionOrderState<T> state;
+  private static final class InCompletionOrderFuture<T extends @Nullable Object>
+      extends AbstractFuture<T> {
+    @CheckForNull private InCompletionOrderState<T> state;
 
     private InCompletionOrderFuture(InCompletionOrderState<T> state) {
       this.state = state;
@@ -916,7 +960,15 @@ private InCompletionOrderFuture(InCompletionOrderState<T> state) {
     public boolean cancel(boolean interruptIfRunning) {
       InCompletionOrderState<T> localState = state;
       if (super.cancel(interruptIfRunning)) {
-        localState.recordOutputCancellation(interruptIfRunning);
+        /*
+         * requireNonNull is generally safe: If cancel succeeded, then this Future was still
+         * pending, so its `state` field hasn't been nulled out yet.
+         *
+         * OK, it's technically possible for this to fail in the presence of unsafe publishing, as
+         * discussed in the comments in TimeoutFuture. TODO(cpovirk): Maybe check for null before
+         * calling recordOutputCancellation?
+         */
+        requireNonNull(localState).recordOutputCancellation(interruptIfRunning);
         return true;
       }
       return false;
@@ -928,6 +980,7 @@ protected void afterDone() {
     }
 
     @Override
+    @CheckForNull
     protected String pendingToString() {
       InCompletionOrderState<T> localState = state;
       if (localState != null) {
@@ -943,14 +996,15 @@ protected String pendingToString() {
     }
   }
 
-  private static final class InCompletionOrderState<T> {
+  private static final class InCompletionOrderState<T extends @Nullable Object> {
     // A happens-before edge between the writes of these fields and their reads exists, because
     // in order to read these fields, the corresponding write to incompleteOutputCount must have
     // been read.
     private boolean wasCancelled = false;
     private boolean shouldInterrupt = true;
     private final AtomicInteger incompleteOutputCount;
-    private final ListenableFuture<? extends T>[] inputFutures;
+    // We set the elements of the array to null as they complete.
+    private final @Nullable ListenableFuture<? extends T>[] inputFutures;
     private volatile int delegateIndex = 0;
 
     private InCompletionOrderState(ListenableFuture<? extends T>[] inputFutures) {
@@ -970,7 +1024,11 @@ private void recordOutputCancellation(boolean interruptIfRunning) {
 
     private void recordInputCompletion(
         ImmutableList<AbstractFuture<T>> delegates, int inputFutureIndex) {
-      ListenableFuture<? extends T> inputFuture = inputFutures[inputFutureIndex];
+      /*
+       * requireNonNull is safe because we accepted an Iterable of non-null Future instances, and we
+       * don't overwrite an element in the array until after reading it.
+       */
+      ListenableFuture<? extends T> inputFuture = requireNonNull(inputFutures[inputFutureIndex]);
       // Null out our reference to this future, so it can be GCed
       inputFutures[inputFutureIndex] = null;
       for (int i = delegateIndex; i < delegates.size(); i++) {
@@ -989,7 +1047,7 @@ private void recordInputCompletion(
 
     private void recordCompletion() {
       if (incompleteOutputCount.decrementAndGet() == 0 && wasCancelled) {
-        for (ListenableFuture<?> toCancel : inputFutures) {
+        for (ListenableFuture<? extends T> toCancel : inputFutures) {
           if (toCancel != null) {
             toCancel.cancel(shouldInterrupt);
           }
@@ -1039,7 +1097,7 @@ private void recordCompletion() {
    * @param executor The executor to run {@code callback} when the future completes.
    * @since 10.0
    */
-  public static <V> void addCallback(
+  public static <V extends @Nullable Object> void addCallback(
       final ListenableFuture<V> future,
       final FutureCallback<? super V> callback,
       Executor executor) {
@@ -1048,7 +1106,7 @@ public static <V> void addCallback(
   }
 
   /** See {@link #addCallback(ListenableFuture, FutureCallback, Executor)} for behavioral notes. */
-  private static final class CallbackListener<V> implements Runnable {
+  private static final class CallbackListener<V extends @Nullable Object> implements Runnable {
     final Future<V> future;
     final FutureCallback<? super V> callback;
 
@@ -1107,7 +1165,8 @@ public String toString() {
    */
   @CanIgnoreReturnValue
   // TODO(cpovirk): Consider calling getDone() in our own code.
-  public static <V> V getDone(Future<V> future) throws ExecutionException {
+  @ParametricNullness
+  public static <V extends @Nullable Object> V getDone(Future<V> future) throws ExecutionException {
     /*
      * We throw IllegalStateException, since the call could succeed later. Perhaps we "should" throw
      * IllegalArgumentException, since the call could succeed with a different argument. Those
@@ -1167,8 +1226,9 @@ public static <V> V getDone(Future<V> future) throws ExecutionException {
   @Beta
   @CanIgnoreReturnValue
   @GwtIncompatible // reflection
-  public static <V, X extends Exception> V getChecked(Future<V> future, Class<X> exceptionClass)
-      throws X {
+  @ParametricNullness
+  public static <V extends @Nullable Object, X extends Exception> V getChecked(
+      Future<V> future, Class<X> exceptionClass) throws X {
     return FuturesGetChecked.getChecked(future, exceptionClass);
   }
 
@@ -1218,7 +1278,8 @@ public static <V, X extends Exception> V getChecked(Future<V> future, Class<X> e
   @Beta
   @CanIgnoreReturnValue
   @GwtIncompatible // reflection
-  public static <V, X extends Exception> V getChecked(
+  @ParametricNullness
+  public static <V extends @Nullable Object, X extends Exception> V getChecked(
       Future<V> future, Class<X> exceptionClass, Duration timeout) throws X {
     return getChecked(future, exceptionClass, toNanosSaturated(timeout), TimeUnit.NANOSECONDS);
   }
@@ -1270,7 +1331,8 @@ public static <V, X extends Exception> V getChecked(
   @CanIgnoreReturnValue
   @GwtIncompatible // reflection
   @SuppressWarnings("GoodTime") // should accept a java.time.Duration
-  public static <V, X extends Exception> V getChecked(
+  @ParametricNullness
+  public static <V extends @Nullable Object, X extends Exception> V getChecked(
       Future<V> future, Class<X> exceptionClass, long timeout, TimeUnit unit) throws X {
     return FuturesGetChecked.getChecked(future, exceptionClass, timeout, unit);
   }
@@ -1310,7 +1372,8 @@ public static <V, X extends Exception> V getChecked(
    * @since 10.0
    */
   @CanIgnoreReturnValue
-  public static <V> V getUnchecked(Future<V> future) {
+  @ParametricNullness
+  public static <V extends @Nullable Object> V getUnchecked(Future<V> future) {
     checkNotNull(future);
     try {
       return getUninterruptibly(future);
@@ -1340,7 +1403,7 @@ private static void wrapAndThrowUnchecked(Throwable cause) {
    * the computation -- makes sense, and if we don't convert it, the user still has to write a
    * try-catch block.
    *
-   * If you think you would use this method, let us know. You might also also look into the
+   * If you think you would use this method, let us know. You might also look into the
    * Fork-Join framework: http://docs.oracle.com/javase/tutorial/essential/concurrency/forkjoin.html
    */
 }
diff --git a/guava/src/com/google/common/util/concurrent/FuturesGetChecked.java b/guava/src/com/google/common/util/concurrent/FuturesGetChecked.java
index 23650408370c..6f09b8066d55 100644
--- a/guava/src/com/google/common/util/concurrent/FuturesGetChecked.java
+++ b/guava/src/com/google/common/util/concurrent/FuturesGetChecked.java
@@ -35,20 +35,25 @@
 import java.util.concurrent.Future;
 import java.util.concurrent.TimeUnit;
 import java.util.concurrent.TimeoutException;
+import javax.annotation.CheckForNull;
 import org.checkerframework.checker.nullness.qual.Nullable;
 
 /** Static methods used to implement {@link Futures#getChecked(Future, Class)}. */
 @GwtIncompatible
+@ElementTypesAreNonnullByDefault
 final class FuturesGetChecked {
   @CanIgnoreReturnValue
-  static <V, X extends Exception> V getChecked(Future<V> future, Class<X> exceptionClass) throws X {
+  @ParametricNullness
+  static <V extends @Nullable Object, X extends Exception> V getChecked(
+      Future<V> future, Class<X> exceptionClass) throws X {
     return getChecked(bestGetCheckedTypeValidator(), future, exceptionClass);
   }
 
   /** Implementation of {@link Futures#getChecked(Future, Class)}. */
   @CanIgnoreReturnValue
   @VisibleForTesting
-  static <V, X extends Exception> V getChecked(
+  @ParametricNullness
+  static <V extends @Nullable Object, X extends Exception> V getChecked(
       GetCheckedTypeValidator validator, Future<V> future, Class<X> exceptionClass) throws X {
     validator.validateClass(exceptionClass);
     try {
@@ -64,7 +69,8 @@ static <V, X extends Exception> V getChecked(
 
   /** Implementation of {@link Futures#getChecked(Future, Class, long, TimeUnit)}. */
   @CanIgnoreReturnValue
-  static <V, X extends Exception> V getChecked(
+  @ParametricNullness
+  static <V extends @Nullable Object, X extends Exception> V getChecked(
       Future<V> future, Class<X> exceptionClass, long timeout, TimeUnit unit) throws X {
     // TODO(cpovirk): benchmark a version of this method that accepts a GetCheckedTypeValidator
     bestGetCheckedTypeValidator().validateClass(exceptionClass);
@@ -114,7 +120,6 @@ static class GetCheckedTypeValidatorHolder {
 
     static final GetCheckedTypeValidator BEST_VALIDATOR = getBestValidator();
 
-    @IgnoreJRERequirement // getChecked falls back to another implementation if necessary
     @J2ObjCIncompatible // ClassValue
     enum ClassValueValidator implements GetCheckedTypeValidator {
       INSTANCE;
@@ -185,7 +190,8 @@ public void validateClass(Class<? extends Exception> exceptionClass) {
      */
     static GetCheckedTypeValidator getBestValidator() {
       try {
-        Class<?> theClass = Class.forName(CLASS_VALUE_VALIDATOR_NAME);
+        Class<? extends Enum> theClass =
+            Class.forName(CLASS_VALUE_VALIDATOR_NAME).asSubclass(Enum.class);
         return (GetCheckedTypeValidator) theClass.getEnumConstants()[0];
       } catch (Throwable t) { // ensure we really catch *everything*
         return weakSetValidator();
@@ -225,7 +231,7 @@ private static <X extends Exception> X newWithCause(Class<X> exceptionClass, Thr
     @SuppressWarnings({"unchecked", "rawtypes"})
     List<Constructor<X>> constructors = (List) Arrays.asList(exceptionClass.getConstructors());
     for (Constructor<X> constructor : preferringStrings(constructors)) {
-      @Nullable X instance = newFromConstructor(constructor, cause);
+      X instance = newFromConstructor(constructor, cause);
       if (instance != null) {
         if (instance.getCause() == null) {
           instance.initCause(cause);
@@ -256,7 +262,8 @@ public Boolean apply(Constructor<?> input) {
               })
           .reverse();
 
-  private static <X> @Nullable X newFromConstructor(Constructor<X> constructor, Throwable cause) {
+  @CheckForNull
+  private static <X> X newFromConstructor(Constructor<X> constructor, Throwable cause) {
     Class<?>[] paramTypes = constructor.getParameterTypes();
     Object[] params = new Object[paramTypes.length];
     for (int i = 0; i < paramTypes.length; i++) {
diff --git a/guava/src/com/google/common/util/concurrent/GwtFluentFutureCatchingSpecialization.java b/guava/src/com/google/common/util/concurrent/GwtFluentFutureCatchingSpecialization.java
index e8acf625af72..d29a673dd854 100644
--- a/guava/src/com/google/common/util/concurrent/GwtFluentFutureCatchingSpecialization.java
+++ b/guava/src/com/google/common/util/concurrent/GwtFluentFutureCatchingSpecialization.java
@@ -15,6 +15,7 @@
 package com.google.common.util.concurrent;
 
 import com.google.common.annotations.GwtCompatible;
+import org.checkerframework.checker.nullness.qual.Nullable;
 
 /**
  * Hidden superclass of {@link FluentFuture} that provides us a place to declare special GWT
@@ -22,7 +23,9 @@
  * FluentFuture.catching} family of methods. Those versions have slightly different signatures.
  */
 @GwtCompatible(emulated = true)
-abstract class GwtFluentFutureCatchingSpecialization<V> extends AbstractFuture<V> {
+@ElementTypesAreNonnullByDefault
+abstract class GwtFluentFutureCatchingSpecialization<V extends @Nullable Object>
+    extends AbstractFuture<V> {
   /*
    * This server copy of the class is empty. The corresponding GWT copy contains alternative
    * versions of catching() and catchingAsync() with slightly different signatures from the ones
diff --git a/guava/src/com/google/common/util/concurrent/GwtFuturesCatchingSpecialization.java b/guava/src/com/google/common/util/concurrent/GwtFuturesCatchingSpecialization.java
index 4626ce949349..95131cec33f6 100644
--- a/guava/src/com/google/common/util/concurrent/GwtFuturesCatchingSpecialization.java
+++ b/guava/src/com/google/common/util/concurrent/GwtFuturesCatchingSpecialization.java
@@ -23,6 +23,7 @@
  * different signatures.
  */
 @GwtCompatible(emulated = true)
+@ElementTypesAreNonnullByDefault
 abstract class GwtFuturesCatchingSpecialization {
   /*
    * This server copy of the class is empty. The corresponding GWT copy contains alternative
diff --git a/guava/src/com/google/common/util/concurrent/IgnoreJRERequirement.java b/guava/src/com/google/common/util/concurrent/IgnoreJRERequirement.java
deleted file mode 100644
index eaaa94f09097..000000000000
--- a/guava/src/com/google/common/util/concurrent/IgnoreJRERequirement.java
+++ /dev/null
@@ -1,24 +0,0 @@
-/*
- * Copyright 2019 The Guava Authors
- *
- * Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file except
- * in compliance with the License. You may obtain a copy of the License at
- *
- * http://www.apache.org/licenses/LICENSE-2.0
- *
- * Unless required by applicable law or agreed to in writing, software distributed under the License
- * is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express
- * or implied. See the License for the specific language governing permissions and limitations under
- * the License.
- */
-
-package com.google.common.util.concurrent;
-
-import static java.lang.annotation.ElementType.CONSTRUCTOR;
-import static java.lang.annotation.ElementType.METHOD;
-import static java.lang.annotation.ElementType.TYPE;
-
-import java.lang.annotation.Target;
-
-@Target({METHOD, CONSTRUCTOR, TYPE})
-@interface IgnoreJRERequirement {}
diff --git a/guava/src/com/google/common/util/concurrent/ImmediateFuture.java b/guava/src/com/google/common/util/concurrent/ImmediateFuture.java
index 7bee37d58d69..8b1c17ae48be 100644
--- a/guava/src/com/google/common/util/concurrent/ImmediateFuture.java
+++ b/guava/src/com/google/common/util/concurrent/ImmediateFuture.java
@@ -27,15 +27,16 @@
 
 /** Implementation of {@link Futures#immediateFuture}. */
 @GwtCompatible
+@ElementTypesAreNonnullByDefault
 // TODO(cpovirk): Make this final (but that may break Mockito spy calls).
-class ImmediateFuture<V> implements ListenableFuture<V> {
-  static final ListenableFuture<?> NULL = new ImmediateFuture<>(null);
+class ImmediateFuture<V extends @Nullable Object> implements ListenableFuture<V> {
+  static final ListenableFuture<?> NULL = new ImmediateFuture<@Nullable Object>(null);
 
   private static final Logger log = Logger.getLogger(ImmediateFuture.class.getName());
 
-  private final @Nullable V value;
+  @ParametricNullness private final V value;
 
-  ImmediateFuture(@Nullable V value) {
+  ImmediateFuture(@ParametricNullness V value) {
     this.value = value;
   }
 
@@ -62,11 +63,13 @@ public boolean cancel(boolean mayInterruptIfRunning) {
 
   // TODO(lukes): Consider throwing InterruptedException when appropriate.
   @Override
+  @ParametricNullness
   public V get() {
     return value;
   }
 
   @Override
+  @ParametricNullness
   public V get(long timeout, TimeUnit unit) throws ExecutionException {
     checkNotNull(unit);
     return get();
@@ -88,13 +91,16 @@ public String toString() {
     return super.toString() + "[status=SUCCESS, result=[" + value + "]]";
   }
 
-  static final class ImmediateFailedFuture<V> extends TrustedFuture<V> {
+  static final class ImmediateFailedFuture<V extends @Nullable Object> extends TrustedFuture<V> {
     ImmediateFailedFuture(Throwable thrown) {
       setException(thrown);
     }
   }
 
-  static final class ImmediateCancelledFuture<V> extends TrustedFuture<V> {
+  static final class ImmediateCancelledFuture<V extends @Nullable Object> extends TrustedFuture<V> {
+    static final @Nullable ImmediateCancelledFuture<Object> INSTANCE =
+        AbstractFuture.GENERATE_CANCELLATION_CAUSES ? null : new ImmediateCancelledFuture<>();
+
     ImmediateCancelledFuture() {
       cancel(false);
     }
diff --git a/guava/src/com/google/common/util/concurrent/Internal.java b/guava/src/com/google/common/util/concurrent/Internal.java
index 8f8382359afd..06bee2ea0919 100644
--- a/guava/src/com/google/common/util/concurrent/Internal.java
+++ b/guava/src/com/google/common/util/concurrent/Internal.java
@@ -19,6 +19,7 @@
 
 /** This class is for {@code com.google.common.util.concurrent} use only! */
 @GwtIncompatible // java.time.Duration
+@ElementTypesAreNonnullByDefault
 final class Internal {
 
   /**
diff --git a/guava/src/com/google/common/util/concurrent/InterruptibleTask.java b/guava/src/com/google/common/util/concurrent/InterruptibleTask.java
index 76537764cd33..bcec007303bd 100644
--- a/guava/src/com/google/common/util/concurrent/InterruptibleTask.java
+++ b/guava/src/com/google/common/util/concurrent/InterruptibleTask.java
@@ -14,20 +14,26 @@
 
 package com.google.common.util.concurrent;
 
+import static com.google.common.util.concurrent.NullnessCasts.uncheckedCastNullableTToT;
+
 import com.google.common.annotations.GwtCompatible;
+import com.google.common.annotations.VisibleForTesting;
 import com.google.j2objc.annotations.ReflectionSupport;
 import java.util.concurrent.atomic.AtomicReference;
+import java.util.concurrent.locks.AbstractOwnableSynchronizer;
 import java.util.concurrent.locks.LockSupport;
 import org.checkerframework.checker.nullness.qual.Nullable;
 
 @GwtCompatible(emulated = true)
 @ReflectionSupport(value = ReflectionSupport.Level.FULL)
+@ElementTypesAreNonnullByDefault
 // Some Android 5.0.x Samsung devices have bugs in JDK reflection APIs that cause
 // getDeclaredField to throw a NoSuchFieldException when the field is definitely there.
 // Since this class only needs CAS on one field, we can avoid this bug by extending AtomicReference
 // instead of using an AtomicReferenceFieldUpdater. This reference stores Thread instances
 // and DONE/INTERRUPTED - they have a common ancestor of Runnable.
-abstract class InterruptibleTask<T> extends AtomicReference<Runnable> implements Runnable {
+abstract class InterruptibleTask<T extends @Nullable Object>
+    extends AtomicReference<@Nullable Runnable> implements Runnable {
   static {
     // Prevent rare disastrous classloading in first call to LockSupport.park.
     // See: https://bugs.openjdk.java.net/browse/JDK-8074773
@@ -42,7 +48,6 @@ public void run() {}
   // The thread executing the task publishes itself to the superclass' reference and the thread
   // interrupting sets DONE when it has finished interrupting.
   private static final Runnable DONE = new DoNothingRunnable();
-  private static final Runnable INTERRUPTING = new DoNothingRunnable();
   private static final Runnable PARKED = new DoNothingRunnable();
   // Why 1000?  WHY NOT!
   private static final int MAX_BUSY_WAIT_SPINS = 1000;
@@ -73,66 +78,83 @@ public final void run() {
     } finally {
       // Attempt to set the task as done so that further attempts to interrupt will fail.
       if (!compareAndSet(currentThread, DONE)) {
-        // If we were interrupted, it is possible that the interrupted bit hasn't been set yet. Wait
-        // for the interrupting thread to set DONE. See interruptTask().
-        // We want to wait so that we don't interrupt the _next_ thing run on the thread.
-        // Note: We don't reset the interrupted bit, just wait for it to be set.
-        // If this is a thread pool thread, the thread pool will reset it for us. Otherwise, the
-        // interrupted bit may have been intended for something else, so don't clear it.
-        boolean restoreInterruptedBit = false;
-        int spinCount = 0;
-        // Interrupting Cow Says:
-        //  ______
-        // < Spin >
-        //  ------
-        //        \   ^__^
-        //         \  (oo)\_______
-        //            (__)\       )\/\
-        //                ||----w |
-        //                ||     ||
-        Runnable state = get();
-        while (state == INTERRUPTING || state == PARKED) {
-          spinCount++;
-          if (spinCount > MAX_BUSY_WAIT_SPINS) {
-            // If we have spun a lot just park ourselves.
-            // This will save CPU while we wait for a slow interrupting thread.  In theory
-            // interruptTask() should be very fast but due to InterruptibleChannel and
-            // JavaLangAccess.blockedOn(Thread, Interruptible), it isn't predictable what work might
-            // be done.  (e.g. close a file and flush buffers to disk).  To protect ourselve from
-            // this we park ourselves and tell our interrupter that we did so.
-            if (state == PARKED || compareAndSet(INTERRUPTING, PARKED)) {
-              // Interrupting Cow Says:
-              //  ______
-              // < Park >
-              //  ------
-              //        \   ^__^
-              //         \  (oo)\_______
-              //            (__)\       )\/\
-              //                ||----w |
-              //                ||     ||
-              // We need to clear the interrupted bit prior to calling park and maintain it in case
-              // we wake up spuriously.
-              restoreInterruptedBit = Thread.interrupted() || restoreInterruptedBit;
-              LockSupport.park(this);
-            }
-          } else {
-            Thread.yield();
-          }
-          state = get();
-        }
-        if (restoreInterruptedBit) {
-          currentThread.interrupt();
+        waitForInterrupt(currentThread);
+      }
+      if (run) {
+        if (error == null) {
+          // The cast is safe because of the `run` and `error` checks.
+          afterRanInterruptiblySuccess(uncheckedCastNullableTToT(result));
+        } else {
+          afterRanInterruptiblyFailure(error);
         }
+      }
+    }
+  }
+
+  private void waitForInterrupt(Thread currentThread) {
+    /*
+     * If someone called cancel(true), it is possible that the interrupted bit hasn't been set yet.
+     * Wait for the interrupting thread to set DONE. (See interruptTask().) We want to wait so that
+     * the interrupting thread doesn't interrupt the _next_ thing to run on this thread.
+     *
+     * Note: We don't reset the interrupted bit, just wait for it to be set. If this is a thread
+     * pool thread, the thread pool will reset it for us. Otherwise, the interrupted bit may have
+     * been intended for something else, so don't clear it.
+     */
+    boolean restoreInterruptedBit = false;
+    int spinCount = 0;
+    // Interrupting Cow Says:
+    //  ______
+    // < Spin >
+    //  ------
+    //        \   ^__^
+    //         \  (oo)\_______
+    //            (__)\       )\/\
+    //                ||----w |
+    //                ||     ||
+    Runnable state = get();
+    Blocker blocker = null;
+    while (state instanceof Blocker || state == PARKED) {
+      if (state instanceof Blocker) {
+        blocker = (Blocker) state;
+      }
+      spinCount++;
+      if (spinCount > MAX_BUSY_WAIT_SPINS) {
         /*
-         * TODO(cpovirk): Clear interrupt status here? We currently don't, which means that an
-         * interrupt before, during, or after runInterruptibly() (unless it produced an
-         * InterruptedException caught above) can linger and affect listeners.
+         * If we have spun a lot, just park ourselves. This will save CPU while we wait for a slow
+         * interrupting thread. In theory, interruptTask() should be very fast, but due to
+         * InterruptibleChannel and JavaLangAccess.blockedOn(Thread, Interruptible), it isn't
+         * predictable what work might be done. (e.g., close a file and flush buffers to disk). To
+         * protect ourselves from this, we park ourselves and tell our interrupter that we did so.
          */
+        if (state == PARKED || compareAndSet(state, PARKED)) {
+          // Interrupting Cow Says:
+          //  ______
+          // < Park >
+          //  ------
+          //        \   ^__^
+          //         \  (oo)\_______
+          //            (__)\       )\/\
+          //                ||----w |
+          //                ||     ||
+          // We need to clear the interrupted bit prior to calling park and maintain it in case we
+          // wake up spuriously.
+          restoreInterruptedBit = Thread.interrupted() || restoreInterruptedBit;
+          LockSupport.park(blocker);
+        }
+      } else {
+        Thread.yield();
       }
-      if (run) {
-        afterRanInterruptibly(result, error);
-      }
+      state = get();
+    }
+    if (restoreInterruptedBit) {
+      currentThread.interrupt();
     }
+    /*
+     * TODO(cpovirk): Clear interrupt status here? We currently don't, which means that an interrupt
+     * before, during, or after runInterruptibly() (unless it produced an InterruptedException
+     * caught above) can linger and affect listeners.
+     */
   }
 
   /**
@@ -145,13 +167,20 @@ public final void run() {
    * Do interruptible work here - do not complete Futures here, as their listeners could be
    * interrupted.
    */
+  @ParametricNullness
   abstract T runInterruptibly() throws Exception;
 
   /**
    * Any interruption that happens as a result of calling interruptTask will arrive before this
    * method is called. Complete Futures here.
    */
-  abstract void afterRanInterruptibly(@Nullable T result, @Nullable Throwable error);
+  abstract void afterRanInterruptiblySuccess(@ParametricNullness T result);
+
+  /**
+   * Any interruption that happens as a result of calling interruptTask will arrive before this
+   * method is called. Complete Futures here.
+   */
+  abstract void afterRanInterruptiblyFailure(Throwable error);
 
   /**
    * Interrupts the running task. Because this internally calls {@link Thread#interrupt()} which can
@@ -162,29 +191,59 @@ final void interruptTask() {
     // in this CAS, there's no risk of interrupting the wrong thread or interrupting a thread that
     // isn't currently executing this task.
     Runnable currentRunner = get();
-    if (currentRunner instanceof Thread && compareAndSet(currentRunner, INTERRUPTING)) {
-      // Thread.interrupt can throw aribitrary exceptions due to the nio InterruptibleChannel API
-      // This will make sure that tasks don't get stuck busy waiting.
-      // Some of this is fixed in jdk11 (see https://bugs.openjdk.java.net/browse/JDK-8198692) but
-      // not all.  See the test cases for examples on how this can happen.
-      try {
-        ((Thread) currentRunner).interrupt();
-      } finally {
-        Runnable prev = getAndSet(DONE);
-        if (prev == PARKED) {
-          LockSupport.unpark((Thread) currentRunner);
+    if (currentRunner instanceof Thread) {
+      Blocker blocker = new Blocker(this);
+      blocker.setOwner(Thread.currentThread());
+      if (compareAndSet(currentRunner, blocker)) {
+        // Thread.interrupt can throw arbitrary exceptions due to the nio InterruptibleChannel API
+        // This will make sure that tasks don't get stuck busy waiting.
+        // Some of this is fixed in jdk11 (see https://bugs.openjdk.java.net/browse/JDK-8198692) but
+        // not all.  See the test cases for examples on how this can happen.
+        try {
+          ((Thread) currentRunner).interrupt();
+        } finally {
+          Runnable prev = getAndSet(DONE);
+          if (prev == PARKED) {
+            LockSupport.unpark((Thread) currentRunner);
+          }
         }
       }
     }
   }
 
+  /**
+   * Using this as the blocker object allows introspection and debugging tools to see that the
+   * currentRunner thread is blocked on the progress of the interruptor thread, which can help
+   * identify deadlocks.
+   */
+  @VisibleForTesting
+  static final class Blocker extends AbstractOwnableSynchronizer implements Runnable {
+    private final InterruptibleTask<?> task;
+
+    private Blocker(InterruptibleTask<?> task) {
+      this.task = task;
+    }
+
+    @Override
+    public void run() {}
+
+    private void setOwner(Thread thread) {
+      super.setExclusiveOwnerThread(thread);
+    }
+
+    @Override
+    public String toString() {
+      return task.toString();
+    }
+  }
+
   @Override
   public final String toString() {
     Runnable state = get();
-    final String result;
+    String result;
     if (state == DONE) {
       result = "running=[DONE]";
-    } else if (state == INTERRUPTING) {
+    } else if (state instanceof Blocker) {
       result = "running=[INTERRUPTED]";
     } else if (state instanceof Thread) {
       // getName is final on Thread, no need to worry about exceptions
diff --git a/guava/src/com/google/common/util/concurrent/JdkFutureAdapters.java b/guava/src/com/google/common/util/concurrent/JdkFutureAdapters.java
index 1b84302e638d..0b0db4573ae2 100644
--- a/guava/src/com/google/common/util/concurrent/JdkFutureAdapters.java
+++ b/guava/src/com/google/common/util/concurrent/JdkFutureAdapters.java
@@ -24,6 +24,7 @@
 import java.util.concurrent.Future;
 import java.util.concurrent.ThreadFactory;
 import java.util.concurrent.atomic.AtomicBoolean;
+import org.checkerframework.checker.nullness.qual.Nullable;
 
 /**
  * Utilities necessary for working with libraries that supply plain {@link Future} instances. Note
@@ -35,6 +36,7 @@
  */
 @Beta
 @GwtIncompatible
+@ElementTypesAreNonnullByDefault
 public final class JdkFutureAdapters {
   /**
    * Assigns a thread to the given {@link Future} to provide {@link ListenableFuture} functionality.
@@ -49,11 +51,12 @@ public final class JdkFutureAdapters {
    * ListenableFutureTask}, {@link AbstractFuture}, and other utilities over creating plain {@code
    * Future} instances to be upgraded to {@code ListenableFuture} after the fact.
    */
-  public static <V> ListenableFuture<V> listenInPoolThread(Future<V> future) {
+  public static <V extends @Nullable Object> ListenableFuture<V> listenInPoolThread(
+      Future<V> future) {
     if (future instanceof ListenableFuture) {
       return (ListenableFuture<V>) future;
     }
-    return new ListenableFutureAdapter<V>(future);
+    return new ListenableFutureAdapter<>(future);
   }
 
   /**
@@ -76,12 +79,13 @@ public static <V> ListenableFuture<V> listenInPoolThread(Future<V> future) {
    *
    * @since 12.0
    */
-  public static <V> ListenableFuture<V> listenInPoolThread(Future<V> future, Executor executor) {
+  public static <V extends @Nullable Object> ListenableFuture<V> listenInPoolThread(
+      Future<V> future, Executor executor) {
     checkNotNull(executor);
     if (future instanceof ListenableFuture) {
       return (ListenableFuture<V>) future;
     }
-    return new ListenableFutureAdapter<V>(future, executor);
+    return new ListenableFutureAdapter<>(future, executor);
   }
 
   /**
@@ -93,8 +97,8 @@ public static <V> ListenableFuture<V> listenInPoolThread(Future<V> future, Execu
    * <p>If the delegate future is interrupted or throws an unexpected unchecked exception, the
    * listeners will not be invoked.
    */
-  private static class ListenableFutureAdapter<V> extends ForwardingFuture<V>
-      implements ListenableFuture<V> {
+  private static class ListenableFutureAdapter<V extends @Nullable Object>
+      extends ForwardingFuture<V> implements ListenableFuture<V> {
 
     private static final ThreadFactory threadFactory =
         new ThreadFactoryBuilder()
@@ -146,22 +150,19 @@ public void addListener(Runnable listener, Executor exec) {
 
         // TODO(lukes): handle RejectedExecutionException
         adapterExecutor.execute(
-            new Runnable() {
-              @Override
-              public void run() {
-                try {
-                  /*
-                   * Threads from our private pool are never interrupted. Threads from a
-                   * user-supplied executor might be, but... what can we do? This is another reason
-                   * to return a proper ListenableFuture instead of using listenInPoolThread.
-                   */
-                  getUninterruptibly(delegate);
-                } catch (Throwable e) {
-                  // ExecutionException / CancellationException / RuntimeException / Error
-                  // The task is presumably done, run the listeners.
-                }
-                executionList.execute();
+            () -> {
+              try {
+                /*
+                 * Threads from our private pool are never interrupted. Threads from a
+                 * user-supplied executor might be, but... what can we do? This is another reason
+                 * to return a proper ListenableFuture instead of using listenInPoolThread.
+                 */
+                getUninterruptibly(delegate);
+              } catch (Throwable e) {
+                // ExecutionException / CancellationException / RuntimeException / Error
+                // The task is presumably done, run the listeners.
               }
+              executionList.execute();
             });
       }
     }
diff --git a/guava/src/com/google/common/util/concurrent/ListenableFuture.java b/guava/src/com/google/common/util/concurrent/ListenableFuture.java
index 98e31ed37466..a8d9dd4de5f9 100644
--- a/guava/src/com/google/common/util/concurrent/ListenableFuture.java
+++ b/guava/src/com/google/common/util/concurrent/ListenableFuture.java
@@ -18,6 +18,7 @@
 import java.util.concurrent.Executor;
 import java.util.concurrent.Future;
 import java.util.concurrent.RejectedExecutionException;
+import org.checkerframework.checker.nullness.qual.Nullable;
 
 /**
  * A {@link Future} that accepts completion listeners. Each listener has an associated executor, and
@@ -99,8 +100,24 @@
  * @author Nishant Thakkar
  * @since 1.0
  */
+/*
+ * Some of the annotations below were added after we released our separate
+ * com.google.guava:listenablefuture:1.0 artifact. (For more on that artifact, see
+ * https://github.com/google/guava/releases/tag/v27.0) This means that the copy of ListenableFuture
+ * in com.google.guava:guava differs from the "frozen" copy in the listenablefuture artifact. This
+ * could in principle cause problems for some users. Still, we expect that the benefits of the
+ * nullness annotations in particular will outweigh the costs. (And it's worth noting that we have
+ * released multiple ListenableFuture.class files that are not byte-for-byte compatible even from
+ * the beginning, thanks to using different `-source -target` values for compiling our `-jre` and
+ * `-android` "flavors.")
+ *
+ * (We could consider releasing a listenablefuture:1.0.1 someday. But we would want to look into how
+ * that affects users, especially users of the Android Gradle Plugin, since the plugin developers
+ * put in a special hack for us: https://issuetracker.google.com/issues/131431257)
+ */
 @DoNotMock("Use the methods in Futures (like immediateFuture) or SettableFuture")
-public interface ListenableFuture<V> extends Future<V> {
+@ElementTypesAreNonnullByDefault
+public interface ListenableFuture<V extends @Nullable Object> extends Future<V> {
   /**
    * Registers a listener to be {@linkplain Executor#execute(Runnable) run} on the given executor.
    * The listener will run when the {@code Future}'s computation is {@linkplain Future#isDone()
diff --git a/guava/src/com/google/common/util/concurrent/ListenableFutureTask.java b/guava/src/com/google/common/util/concurrent/ListenableFutureTask.java
index eccc4d320b17..678a6c671a46 100644
--- a/guava/src/com/google/common/util/concurrent/ListenableFutureTask.java
+++ b/guava/src/com/google/common/util/concurrent/ListenableFutureTask.java
@@ -41,7 +41,9 @@
  * @since 1.0
  */
 @GwtIncompatible
-public class ListenableFutureTask<V> extends FutureTask<V> implements ListenableFuture<V> {
+@ElementTypesAreNonnullByDefault
+public class ListenableFutureTask<V extends @Nullable Object> extends FutureTask<V>
+    implements ListenableFuture<V> {
   // TODO(cpovirk): explore ways of making ListenableFutureTask final. There are some valid reasons
   // such as BoundedQueueExecutorService to allow extends but it would be nice to make it final to
   // avoid unintended usage.
@@ -56,8 +58,8 @@ public class ListenableFutureTask<V> extends FutureTask<V> implements Listenable
    * @param callable the callable task
    * @since 10.0
    */
-  public static <V> ListenableFutureTask<V> create(Callable<V> callable) {
-    return new ListenableFutureTask<V>(callable);
+  public static <V extends @Nullable Object> ListenableFutureTask<V> create(Callable<V> callable) {
+    return new ListenableFutureTask<>(callable);
   }
 
   /**
@@ -70,15 +72,16 @@ public static <V> ListenableFutureTask<V> create(Callable<V> callable) {
    *     ListenableFutureTask.create(runnable, null)}
    * @since 10.0
    */
-  public static <V> ListenableFutureTask<V> create(Runnable runnable, @Nullable V result) {
-    return new ListenableFutureTask<V>(runnable, result);
+  public static <V extends @Nullable Object> ListenableFutureTask<V> create(
+      Runnable runnable, @ParametricNullness V result) {
+    return new ListenableFutureTask<>(runnable, result);
   }
 
   ListenableFutureTask(Callable<V> callable) {
     super(callable);
   }
 
-  ListenableFutureTask(Runnable runnable, @Nullable V result) {
+  ListenableFutureTask(Runnable runnable, @ParametricNullness V result) {
     super(runnable, result);
   }
 
@@ -89,6 +92,7 @@ public void addListener(Runnable listener, Executor exec) {
 
   @CanIgnoreReturnValue
   @Override
+  @ParametricNullness
   public V get(long timeout, TimeUnit unit)
       throws TimeoutException, InterruptedException, ExecutionException {
 
diff --git a/guava/src/com/google/common/util/concurrent/ListenableScheduledFuture.java b/guava/src/com/google/common/util/concurrent/ListenableScheduledFuture.java
index 77fa5f7fc69b..f6e5d9f9e1ec 100644
--- a/guava/src/com/google/common/util/concurrent/ListenableScheduledFuture.java
+++ b/guava/src/com/google/common/util/concurrent/ListenableScheduledFuture.java
@@ -14,9 +14,9 @@
 
 package com.google.common.util.concurrent;
 
-import com.google.common.annotations.Beta;
 import com.google.common.annotations.GwtCompatible;
 import java.util.concurrent.ScheduledFuture;
+import org.checkerframework.checker.nullness.qual.Nullable;
 
 /**
  * Helper interface to implement both {@link ListenableFuture} and {@link ScheduledFuture}.
@@ -24,6 +24,7 @@
  * @author Anthony Zana
  * @since 15.0
  */
-@Beta
 @GwtCompatible
-public interface ListenableScheduledFuture<V> extends ScheduledFuture<V>, ListenableFuture<V> {}
+@ElementTypesAreNonnullByDefault
+public interface ListenableScheduledFuture<V extends @Nullable Object>
+    extends ScheduledFuture<V>, ListenableFuture<V> {}
diff --git a/guava/src/com/google/common/util/concurrent/ListenerCallQueue.java b/guava/src/com/google/common/util/concurrent/ListenerCallQueue.java
index ee6b5b94c964..ed8c9065ac93 100644
--- a/guava/src/com/google/common/util/concurrent/ListenerCallQueue.java
+++ b/guava/src/com/google/common/util/concurrent/ListenerCallQueue.java
@@ -53,6 +53,7 @@
  * #dispatch} is expected to be called concurrently, it is idempotent.
  */
 @GwtIncompatible
+@ElementTypesAreNonnullByDefault
 final class ListenerCallQueue<L> {
   // TODO(cpovirk): consider using the logger associated with listener.getClass().
   private static final Logger logger = Logger.getLogger(ListenerCallQueue.class.getName());
@@ -123,7 +124,7 @@ public void dispatch() {
 
   /**
    * A special purpose queue/executor that dispatches listener events serially on a configured
-   * executor. Each event event can be added and dispatched as separate phases.
+   * executor. Each event can be added and dispatched as separate phases.
    *
    * <p>This class is very similar to {@link SequentialExecutor} with the exception that events can
    * be added without necessarily executing immediately.
diff --git a/guava/src/com/google/common/util/concurrent/ListeningExecutorService.java b/guava/src/com/google/common/util/concurrent/ListeningExecutorService.java
index 469eb6757a09..83ea759f8e74 100644
--- a/guava/src/com/google/common/util/concurrent/ListeningExecutorService.java
+++ b/guava/src/com/google/common/util/concurrent/ListeningExecutorService.java
@@ -23,6 +23,7 @@
 import java.util.concurrent.Future;
 import java.util.concurrent.RejectedExecutionException;
 import java.util.concurrent.TimeUnit;
+import org.checkerframework.checker.nullness.qual.Nullable;
 
 /**
  * An {@link ExecutorService} that returns {@link ListenableFuture} instances. To create an instance
@@ -36,13 +37,14 @@
     "Use TestingExecutors.sameThreadScheduledExecutor, or wrap a real Executor from "
         + "java.util.concurrent.Executors with MoreExecutors.listeningDecorator")
 @GwtIncompatible
+@ElementTypesAreNonnullByDefault
 public interface ListeningExecutorService extends ExecutorService {
   /**
    * @return a {@code ListenableFuture} representing pending completion of the task
    * @throws RejectedExecutionException {@inheritDoc}
    */
   @Override
-  <T> ListenableFuture<T> submit(Callable<T> task);
+  <T extends @Nullable Object> ListenableFuture<T> submit(Callable<T> task);
 
   /**
    * @return a {@code ListenableFuture} representing pending completion of the task
@@ -56,7 +58,8 @@ public interface ListeningExecutorService extends ExecutorService {
    * @throws RejectedExecutionException {@inheritDoc}
    */
   @Override
-  <T> ListenableFuture<T> submit(Runnable task, T result);
+  <T extends @Nullable Object> ListenableFuture<T> submit(
+      Runnable task, @ParametricNullness T result);
 
   /**
    * {@inheritDoc}
@@ -77,7 +80,7 @@ public interface ListeningExecutorService extends ExecutorService {
    * @throws NullPointerException if any task is null
    */
   @Override
-  <T> List<Future<T>> invokeAll(Collection<? extends Callable<T>> tasks)
+  <T extends @Nullable Object> List<Future<T>> invokeAll(Collection<? extends Callable<T>> tasks)
       throws InterruptedException;
 
   /**
@@ -100,7 +103,7 @@ <T> List<Future<T>> invokeAll(Collection<? extends Callable<T>> tasks)
    * @throws NullPointerException if any task is null
    */
   @Override
-  <T> List<Future<T>> invokeAll(
+  <T extends @Nullable Object> List<Future<T>> invokeAll(
       Collection<? extends Callable<T>> tasks, long timeout, TimeUnit unit)
       throws InterruptedException;
 }
diff --git a/guava/src/com/google/common/util/concurrent/ListeningScheduledExecutorService.java b/guava/src/com/google/common/util/concurrent/ListeningScheduledExecutorService.java
index 6410e83f8482..25185b91a454 100644
--- a/guava/src/com/google/common/util/concurrent/ListeningScheduledExecutorService.java
+++ b/guava/src/com/google/common/util/concurrent/ListeningScheduledExecutorService.java
@@ -21,6 +21,7 @@
 import java.util.concurrent.Callable;
 import java.util.concurrent.ScheduledExecutorService;
 import java.util.concurrent.TimeUnit;
+import org.checkerframework.checker.nullness.qual.Nullable;
 
 /**
  * A {@link ScheduledExecutorService} that returns {@link ListenableFuture} instances from its
@@ -32,6 +33,7 @@
  * @since 10.0
  */
 @GwtIncompatible
+@ElementTypesAreNonnullByDefault
 public interface ListeningScheduledExecutorService
     extends ScheduledExecutorService, ListeningExecutorService {
 
@@ -50,14 +52,16 @@ default ListenableScheduledFuture<?> schedule(Runnable command, Duration delay)
 
   /** @since 15.0 (previously returned ScheduledFuture) */
   @Override
-  <V> ListenableScheduledFuture<V> schedule(Callable<V> callable, long delay, TimeUnit unit);
+  <V extends @Nullable Object> ListenableScheduledFuture<V> schedule(
+      Callable<V> callable, long delay, TimeUnit unit);
 
   /**
    * Duration-based overload of {@link #schedule(Callable, long, TimeUnit)}.
    *
    * @since 29.0
    */
-  default <V> ListenableScheduledFuture<V> schedule(Callable<V> callable, Duration delay) {
+  default <V extends @Nullable Object> ListenableScheduledFuture<V> schedule(
+      Callable<V> callable, Duration delay) {
     return schedule(callable, toNanosSaturated(delay), TimeUnit.NANOSECONDS);
   }
 
diff --git a/guava/src/com/google/common/util/concurrent/Monitor.java b/guava/src/com/google/common/util/concurrent/Monitor.java
index dcdd7b66a13a..d01c6faa2aee 100644
--- a/guava/src/com/google/common/util/concurrent/Monitor.java
+++ b/guava/src/com/google/common/util/concurrent/Monitor.java
@@ -17,7 +17,6 @@
 import static com.google.common.base.Preconditions.checkNotNull;
 import static com.google.common.util.concurrent.Internal.toNanosSaturated;
 
-import com.google.common.annotations.Beta;
 import com.google.common.annotations.GwtIncompatible;
 import com.google.common.primitives.Longs;
 import com.google.errorprone.annotations.concurrent.GuardedBy;
@@ -27,7 +26,7 @@
 import java.util.concurrent.locks.Condition;
 import java.util.concurrent.locks.ReentrantLock;
 import java.util.function.BooleanSupplier;
-import org.checkerframework.checker.nullness.qual.Nullable;
+import javax.annotation.CheckForNull;
 
 /**
  * A synchronization abstraction supporting waiting on arbitrary boolean conditions.
@@ -200,9 +199,9 @@
  * @author Martin Buchholz
  * @since 10.0
  */
-@Beta
 @GwtIncompatible
 @SuppressWarnings("GuardedBy") // TODO(b/35466881): Fix or suppress.
+@ElementTypesAreNonnullByDefault
 public final class Monitor {
   // TODO(user): Use raw LockSupport or AbstractQueuedSynchronizer instead of ReentrantLock.
   // TODO(user): "Port" jsr166 tests for ReentrantLock.
@@ -303,7 +302,6 @@ public final class Monitor {
    *
    * @since 10.0
    */
-  @Beta
   public abstract static class Guard {
 
     @Weak final Monitor monitor;
@@ -314,7 +312,7 @@ public abstract static class Guard {
 
     /** The next active guard */
     @GuardedBy("monitor.lock")
-    @Nullable
+    @CheckForNull
     Guard next;
 
     protected Guard(Monitor monitor) {
@@ -341,6 +339,7 @@ protected Guard(Monitor monitor) {
    * A linked list threaded through the Guard.next field.
    */
   @GuardedBy("lock")
+  @CheckForNull
   private Guard activeGuards = null;
 
   /**
@@ -820,7 +819,7 @@ public boolean tryEnterIf(Guard guard) {
    * @throws InterruptedException if interrupted while waiting
    */
   public void waitFor(Guard guard) throws InterruptedException {
-    if (!((guard.monitor == this) & lock.isHeldByCurrentThread())) {
+    if (!((guard.monitor == this) && lock.isHeldByCurrentThread())) {
       throw new IllegalMonitorStateException();
     }
     if (!guard.isSatisfied()) {
@@ -850,7 +849,7 @@ public boolean waitFor(Guard guard, Duration time) throws InterruptedException {
   @SuppressWarnings("GoodTime") // should accept a java.time.Duration
   public boolean waitFor(Guard guard, long time, TimeUnit unit) throws InterruptedException {
     final long timeoutNanos = toSafeNanos(time, unit);
-    if (!((guard.monitor == this) & lock.isHeldByCurrentThread())) {
+    if (!((guard.monitor == this) && lock.isHeldByCurrentThread())) {
       throw new IllegalMonitorStateException();
     }
     if (guard.isSatisfied()) {
@@ -867,7 +866,7 @@ public boolean waitFor(Guard guard, long time, TimeUnit unit) throws Interrupted
    * currently occupying this monitor.
    */
   public void waitForUninterruptibly(Guard guard) {
-    if (!((guard.monitor == this) & lock.isHeldByCurrentThread())) {
+    if (!((guard.monitor == this) && lock.isHeldByCurrentThread())) {
       throw new IllegalMonitorStateException();
     }
     if (!guard.isSatisfied()) {
@@ -895,7 +894,7 @@ public boolean waitForUninterruptibly(Guard guard, Duration time) {
   @SuppressWarnings("GoodTime") // should accept a java.time.Duration
   public boolean waitForUninterruptibly(Guard guard, long time, TimeUnit unit) {
     final long timeoutNanos = toSafeNanos(time, unit);
-    if (!((guard.monitor == this) & lock.isHeldByCurrentThread())) {
+    if (!((guard.monitor == this) && lock.isHeldByCurrentThread())) {
       throw new IllegalMonitorStateException();
     }
     if (guard.isSatisfied()) {
diff --git a/guava/src/com/google/common/util/concurrent/MoreExecutors.java b/guava/src/com/google/common/util/concurrent/MoreExecutors.java
index 0cc64ec8d832..90776bc9e69b 100644
--- a/guava/src/com/google/common/util/concurrent/MoreExecutors.java
+++ b/guava/src/com/google/common/util/concurrent/MoreExecutors.java
@@ -51,6 +51,7 @@
 import java.util.concurrent.ThreadPoolExecutor;
 import java.util.concurrent.TimeUnit;
 import java.util.concurrent.TimeoutException;
+import org.checkerframework.checker.nullness.qual.Nullable;
 
 /**
  * Factory and utility methods for {@link java.util.concurrent.Executor}, {@link ExecutorService},
@@ -62,6 +63,7 @@
  * @since 3.0
  */
 @GwtCompatible(emulated = true)
+@ElementTypesAreNonnullByDefault
 public final class MoreExecutors {
   private MoreExecutors() {}
 
@@ -438,14 +440,22 @@ public static ListeningExecutorService newDirectExecutorService() {
    * difficult to reproduce because they depend on timing. For example:
    *
    * <ul>
-   *   <li>A call like {@code future.transform(function, directExecutor())} may execute the function
-   *       immediately in the thread that is calling {@code transform}. (This specific case happens
-   *       if the future is already completed.) If {@code transform} call was made from a UI thread
-   *       or other latency-sensitive thread, a heavyweight function can harm responsiveness.
-   *   <li>If the task will be executed later, consider which thread will trigger the execution --
-   *       since that thread will execute the task inline. If the thread is a shared system thread
-   *       like an RPC network thread, a heavyweight task can stall progress of the whole system or
-   *       even deadlock it.
+   *   <li>When a {@code ListenableFuture} listener is registered to run under {@code
+   *       directExecutor}, the listener can execute in any of three possible threads:
+   *       <ol>
+   *         <li>When a thread attaches a listener to a {@code ListenableFuture} that's already
+   *             complete, the listener runs immediately in that thread.
+   *         <li>When a thread attaches a listener to a {@code ListenableFuture} that's
+   *             <em>in</em>complete and the {@code ListenableFuture} later completes normally, the
+   *             listener runs in the the thread that completes the {@code ListenableFuture}.
+   *         <li>When a listener is attached to a {@code ListenableFuture} and the {@code
+   *             ListenableFuture} gets cancelled, the listener runs immediately in the the thread
+   *             that cancelled the {@code Future}.
+   *       </ol>
+   *       Given all these possibilities, it is frequently possible for listeners to execute in UI
+   *       threads, RPC network threads, or other latency-sensitive threads. In those cases, slow
+   *       listeners can harm responsiveness, slow the system as a whole, or worse. (See also the
+   *       note about locking below.)
    *   <li>If many tasks will be triggered by the same event, one heavyweight task may delay other
    *       tasks -- even tasks that are not themselves {@code directExecutor} tasks.
    *   <li>If many such tasks are chained together (such as with {@code
@@ -453,11 +463,19 @@ public static ListeningExecutorService newDirectExecutorService() {
    *       (In simple cases, callers can avoid this by registering all tasks with the same {@link
    *       MoreExecutors#newSequentialExecutor} wrapper around {@code directExecutor()}. More
    *       complex cases may require using thread pools or making deeper changes.)
+   *   <li>If an exception propagates out of a {@code Runnable}, it is not necessarily seen by any
+   *       {@code UncaughtExceptionHandler} for the thread. For example, if the callback passed to
+   *       {@link Futures#addCallback} throws an exception, that exception will be typically be
+   *       logged by the {@link ListenableFuture} implementation, even if the thread is configured
+   *       to do something different. In other cases, no code will catch the exception, and it may
+   *       terminate whichever thread happens to trigger the execution.
    * </ul>
    *
-   * Additionally, beware of executing tasks with {@code directExecutor} while holding a lock. Since
-   * the task you submit to the executor (or any other arbitrary work the executor does) may do slow
-   * work or acquire other locks, you risk deadlocks.
+   * A specific warning about locking: Code that executes user-supplied tasks, such as {@code
+   * ListenableFuture} listeners, should take care not to do so while holding a lock. Additionally,
+   * as a further line of defense, prefer not to perform any locking inside a task that will be run
+   * under {@code directExecutor}: Not only might the wait for a lock be long, but if the running
+   * thread was holding a lock, the listener may deadlock or break lock isolation.
    *
    * <p>This instance is equivalent to:
    *
@@ -480,8 +498,11 @@ public static Executor directExecutor() {
 
   /**
    * Returns an {@link Executor} that runs each task executed sequentially, such that no two tasks
-   * are running concurrently. Submitted tasks have a happens-before order as defined in the Java
-   * Language Specification.
+   * are running concurrently.
+   *
+   * <p>{@linkplain Executor#execute executed} tasks have a happens-before order as defined in the
+   * Java Language Specification. Tasks execute with the same happens-before order that the function
+   * calls to {@link Executor#execute `execute()`} that submitted those tasks had.
    *
    * <p>The executor uses {@code delegate} in order to {@link Executor#execute execute} each task in
    * turn, and does not create any threads of its own.
@@ -519,7 +540,6 @@ public static Executor directExecutor() {
    *
    * @since 23.3 (since 23.1 as {@code sequentialExecutor})
    */
-  @Beta
   @GwtIncompatible
   public static Executor newSequentialExecutor(Executor delegate) {
     return new SequentialExecutor(delegate);
@@ -610,6 +630,11 @@ public final List<Runnable> shutdownNow() {
     public final void execute(Runnable command) {
       delegate.execute(command);
     }
+
+    @Override
+    public final String toString() {
+      return super.toString() + "[" + delegate + "]";
+    }
   }
 
   @GwtIncompatible // TODO
@@ -625,13 +650,14 @@ private static final class ScheduledListeningDecorator extends ListeningDecorato
 
     @Override
     public ListenableScheduledFuture<?> schedule(Runnable command, long delay, TimeUnit unit) {
-      TrustedListenableFutureTask<Void> task = TrustedListenableFutureTask.create(command, null);
+      TrustedListenableFutureTask<@Nullable Void> task =
+          TrustedListenableFutureTask.create(command, null);
       ScheduledFuture<?> scheduled = delegate.schedule(task, delay, unit);
-      return new ListenableScheduledTask<>(task, scheduled);
+      return new ListenableScheduledTask<@Nullable Void>(task, scheduled);
     }
 
     @Override
-    public <V> ListenableScheduledFuture<V> schedule(
+    public <V extends @Nullable Object> ListenableScheduledFuture<V> schedule(
         Callable<V> callable, long delay, TimeUnit unit) {
       TrustedListenableFutureTask<V> task = TrustedListenableFutureTask.create(callable);
       ScheduledFuture<?> scheduled = delegate.schedule(task, delay, unit);
@@ -643,7 +669,7 @@ public ListenableScheduledFuture<?> scheduleAtFixedRate(
         Runnable command, long initialDelay, long period, TimeUnit unit) {
       NeverSuccessfulListenableFutureTask task = new NeverSuccessfulListenableFutureTask(command);
       ScheduledFuture<?> scheduled = delegate.scheduleAtFixedRate(task, initialDelay, period, unit);
-      return new ListenableScheduledTask<>(task, scheduled);
+      return new ListenableScheduledTask<@Nullable Void>(task, scheduled);
     }
 
     @Override
@@ -652,10 +678,10 @@ public ListenableScheduledFuture<?> scheduleWithFixedDelay(
       NeverSuccessfulListenableFutureTask task = new NeverSuccessfulListenableFutureTask(command);
       ScheduledFuture<?> scheduled =
           delegate.scheduleWithFixedDelay(task, initialDelay, delay, unit);
-      return new ListenableScheduledTask<>(task, scheduled);
+      return new ListenableScheduledTask<@Nullable Void>(task, scheduled);
     }
 
-    private static final class ListenableScheduledTask<V>
+    private static final class ListenableScheduledTask<V extends @Nullable Object>
         extends SimpleForwardingListenableFuture<V> implements ListenableScheduledFuture<V> {
 
       private final ScheduledFuture<?> scheduledDelegate;
@@ -691,7 +717,7 @@ public int compareTo(Delayed other) {
 
     @GwtIncompatible // TODO
     private static final class NeverSuccessfulListenableFutureTask
-        extends AbstractFuture.TrustedFuture<Void> implements Runnable {
+        extends AbstractFuture.TrustedFuture<@Nullable Void> implements Runnable {
       private final Runnable delegate;
 
       public NeverSuccessfulListenableFutureTask(Runnable delegate) {
@@ -707,6 +733,11 @@ public void run() {
           throw Throwables.propagate(t);
         }
       }
+
+      @Override
+      protected String pendingToString() {
+        return "task=[" + delegate + "]";
+      }
     }
   }
 
@@ -726,7 +757,8 @@ public void run() {
    * implementations.
    */
   @GwtIncompatible
-  static <T> T invokeAnyImpl(
+  @ParametricNullness
+  static <T extends @Nullable Object> T invokeAnyImpl(
       ListeningExecutorService executorService,
       Collection<? extends Callable<T>> tasks,
       boolean timed,
@@ -742,7 +774,8 @@ static <T> T invokeAnyImpl(
    */
   @SuppressWarnings("GoodTime") // should accept a java.time.Duration
   @GwtIncompatible
-  static <T> T invokeAnyImpl(
+  @ParametricNullness
+  static <T extends @Nullable Object> T invokeAnyImpl(
       ListeningExecutorService executorService,
       Collection<? extends Callable<T>> tasks,
       boolean timed,
@@ -822,7 +855,7 @@ static <T> T invokeAnyImpl(
    * Submits the task and adds a listener that adds the future to {@code queue} when it completes.
    */
   @GwtIncompatible // TODO
-  private static <T> ListenableFuture<T> submitAndAddQueueListener(
+  private static <T extends @Nullable Object> ListenableFuture<T> submitAndAddQueueListener(
       ListeningExecutorService executorService,
       Callable<T> task,
       final BlockingQueue<Future<T>> queue) {
@@ -967,7 +1000,7 @@ static ExecutorService renamingDecorator(
     checkNotNull(nameSupplier);
     return new WrappingExecutorService(service) {
       @Override
-      protected <T> Callable<T> wrapTask(Callable<T> callable) {
+      protected <T extends @Nullable Object> Callable<T> wrapTask(Callable<T> callable) {
         return Callables.threadRenaming(callable, nameSupplier);
       }
 
@@ -996,7 +1029,7 @@ static ScheduledExecutorService renamingDecorator(
     checkNotNull(nameSupplier);
     return new WrappingScheduledExecutorService(service) {
       @Override
-      protected <T> Callable<T> wrapTask(Callable<T> callable) {
+      protected <T extends @Nullable Object> Callable<T> wrapTask(Callable<T> callable) {
         return Callables.threadRenaming(callable, nameSupplier);
       }
 
diff --git a/guava/src/com/google/common/util/concurrent/NullnessCasts.java b/guava/src/com/google/common/util/concurrent/NullnessCasts.java
new file mode 100644
index 000000000000..a3a914e8970a
--- /dev/null
+++ b/guava/src/com/google/common/util/concurrent/NullnessCasts.java
@@ -0,0 +1,76 @@
+/*
+ * Copyright (C) 2021 The Guava Authors
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file except
+ * in compliance with the License. You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software distributed under the License
+ * is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express
+ * or implied. See the License for the specific language governing permissions and limitations under
+ * the License.
+ */
+
+package com.google.common.util.concurrent;
+
+import com.google.common.annotations.GwtCompatible;
+import javax.annotation.CheckForNull;
+import org.checkerframework.checker.nullness.qual.Nullable;
+
+/** A utility method to perform unchecked casts to suppress errors produced by nullness analyses. */
+@GwtCompatible
+@ElementTypesAreNonnullByDefault
+final class NullnessCasts {
+  /**
+   * Accepts a {@code @Nullable T} and returns a plain {@code T}, without performing any check that
+   * that conversion is safe.
+   *
+   * <p>This method is intended to help with usages of type parameters that have {@linkplain
+   * ParametricNullness parametric nullness}. If a type parameter instead ranges over only non-null
+   * types (or if the type is a non-variable type, like {@code String}), then code should almost
+   * never use this method, preferring instead to call {@code requireNonNull} so as to benefit from
+   * its runtime check.
+   *
+   * <p>An example use case for this method is in implementing an {@code Iterator<T>} whose {@code
+   * next} field is lazily initialized. The type of that field would be {@code @Nullable T}, and the
+   * code would be responsible for populating a "real" {@code T} (which might still be the value
+   * {@code null}!) before returning it to callers. Depending on how the code is structured, a
+   * nullness analysis might not understand that the field has been populated. To avoid that problem
+   * without having to add {@code @SuppressWarnings}, the code can call this method.
+   *
+   * <p>Why <i>not</i> just add {@code SuppressWarnings}? The problem is that this method is
+   * typically useful for {@code return} statements. That leaves the code with two options: Either
+   * add the suppression to the whole method (which turns off checking for a large section of code),
+   * or extract a variable, and put the suppression on that. However, a local variable typically
+   * doesn't work: Because nullness analyses typically infer the nullness of local variables,
+   * there's no way to assign a {@code @Nullable T} to a field {@code T foo;} and instruct the
+   * analysis that that means "plain {@code T}" rather than the inferred type {@code @Nullable T}.
+   * (Even if supported added {@code @NonNull}, that would not help, since the problem case
+   * addressed by this method is the case in which {@code T} has parametric nullness -- and thus its
+   * value may be legitimately {@code null}.)
+   */
+  @SuppressWarnings("nullness")
+  @ParametricNullness
+  static <T extends @Nullable Object> T uncheckedCastNullableTToT(@CheckForNull T t) {
+    return t;
+  }
+
+  /**
+   * Returns {@code null} cast to any type.
+   *
+   * <p>This method is intended to help with usages of type parameters that have {@linkplain
+   * ParametricNullness parametric nullness}. Sometimes, code may receive a null {@code T} but store
+   * a "null sentinel" to take its place. When the time comes to convert it back to a {@code T} to
+   * return to a caller, the code needs to a way to return {@code null} from a method that returns
+   * "plain {@code T}." This API provides that.
+   */
+  @SuppressWarnings({"nullness", "TypeParameterUnusedInFormals", "ReturnMissingNullable"})
+  // The warnings are legitimate. Each time we use this method, we document why.
+  @ParametricNullness
+  static <T extends @Nullable Object> T uncheckedNull() {
+    return null;
+  }
+
+  private NullnessCasts() {}
+}
diff --git a/guava/src/com/google/common/util/concurrent/OverflowAvoidingLockSupport.java b/guava/src/com/google/common/util/concurrent/OverflowAvoidingLockSupport.java
index aa07abfe071a..3038ab7bd004 100644
--- a/guava/src/com/google/common/util/concurrent/OverflowAvoidingLockSupport.java
+++ b/guava/src/com/google/common/util/concurrent/OverflowAvoidingLockSupport.java
@@ -17,19 +17,20 @@
 import static java.lang.Math.min;
 
 import java.util.concurrent.locks.LockSupport;
-import org.checkerframework.checker.nullness.qual.Nullable;
+import javax.annotation.CheckForNull;
 
 /**
  * Works around an android bug, where parking for more than INT_MAX seconds can produce an abort
  * signal on 32 bit devices running Android Q.
  */
+@ElementTypesAreNonnullByDefault
 final class OverflowAvoidingLockSupport {
   // Represents the max nanoseconds representable on a linux timespec with a 32 bit tv_sec
   static final long MAX_NANOSECONDS_THRESHOLD = (1L + Integer.MAX_VALUE) * 1_000_000_000L - 1L;
 
   private OverflowAvoidingLockSupport() {}
 
-  static void parkNanos(@Nullable Object blocker, long nanos) {
+  static void parkNanos(@CheckForNull Object blocker, long nanos) {
     // Even in the extremely unlikely event that a thread unblocks itself early after only 68 years,
     // this is indistinguishable from a spurious wakeup, which LockSupport allows.
     LockSupport.parkNanos(blocker, min(nanos, MAX_NANOSECONDS_THRESHOLD));
diff --git a/guava/src/com/google/common/util/concurrent/ParametricNullness.java b/guava/src/com/google/common/util/concurrent/ParametricNullness.java
new file mode 100644
index 000000000000..a745bf7bb4b8
--- /dev/null
+++ b/guava/src/com/google/common/util/concurrent/ParametricNullness.java
@@ -0,0 +1,52 @@
+/*
+ * Copyright (C) 2021 The Guava Authors
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package com.google.common.util.concurrent;
+
+import static java.lang.annotation.ElementType.FIELD;
+import static java.lang.annotation.ElementType.METHOD;
+import static java.lang.annotation.ElementType.PARAMETER;
+import static java.lang.annotation.RetentionPolicy.RUNTIME;
+
+import com.google.common.annotations.GwtCompatible;
+import java.lang.annotation.Retention;
+import java.lang.annotation.Target;
+
+/**
+ * Marks a "top-level" type-variable usage as the closest we can get to "non-nullable when
+ * non-nullable; nullable when nullable" (like the Android <a
+ * href="https://android.googlesource.com/platform/libcore/+/master/luni/src/main/java/libcore/util/NullFromTypeParam.java">{@code
+ * NullFromTypeParam}</a>).
+ *
+ * <p>Consumers of this annotation include:
+ *
+ * <ul>
+ *   <li>Kotlin, for which it makes the type-variable usage (a) a Kotlin platform type when the type
+ *       argument is non-nullable and (b) nullable when the type argument is nullable. We use this
+ *       to "undo" {@link ElementTypesAreNonnullByDefault}.
+ *   <li><a href="https://developers.google.com/j2objc">J2ObjC</a>
+ *   <li>{@code NullPointerTester}, at least in the Android backport (where the type-use annotations
+ *       {@code NullPointerTester} would need are not available) and in case of <a
+ *       href="https://bugs.openjdk.java.net/browse/JDK-8202469">JDK-8202469</a>
+ * </ul>
+ *
+ */
+@GwtCompatible
+@Retention(RUNTIME)
+@Target({FIELD, METHOD, PARAMETER})
+@javax.annotation.meta.TypeQualifierNickname
+@javax.annotation.Nonnull(when = javax.annotation.meta.When.UNKNOWN)
+@interface ParametricNullness {}
diff --git a/guava/src/com/google/common/util/concurrent/Partially.java b/guava/src/com/google/common/util/concurrent/Partially.java
index c40ab4e007ee..7aa16e776fd5 100644
--- a/guava/src/com/google/common/util/concurrent/Partially.java
+++ b/guava/src/com/google/common/util/concurrent/Partially.java
@@ -32,6 +32,7 @@
  * version.
  */
 @GwtCompatible
+@ElementTypesAreNonnullByDefault
 final class Partially {
   /**
    * The presence of this annotation on an API indicates that the method <i>may</i> be used with the
diff --git a/guava/src/com/google/common/util/concurrent/Platform.java b/guava/src/com/google/common/util/concurrent/Platform.java
index f27bfb383ae0..cfb96a0ad788 100644
--- a/guava/src/com/google/common/util/concurrent/Platform.java
+++ b/guava/src/com/google/common/util/concurrent/Platform.java
@@ -15,13 +15,14 @@
 package com.google.common.util.concurrent;
 
 import com.google.common.annotations.GwtCompatible;
-import org.checkerframework.checker.nullness.qual.Nullable;
+import javax.annotation.CheckForNull;
 
 /** Methods factored out so that they can be emulated differently in GWT. */
 @GwtCompatible(emulated = true)
+@ElementTypesAreNonnullByDefault
 final class Platform {
   static boolean isInstanceOfThrowableClass(
-      @Nullable Throwable t, Class<? extends Throwable> expectedClass) {
+      @CheckForNull Throwable t, Class<? extends Throwable> expectedClass) {
     return expectedClass.isInstance(t);
   }
 
diff --git a/guava/src/com/google/common/util/concurrent/RateLimiter.java b/guava/src/com/google/common/util/concurrent/RateLimiter.java
index ec041d48fe7b..4b8b02554165 100644
--- a/guava/src/com/google/common/util/concurrent/RateLimiter.java
+++ b/guava/src/com/google/common/util/concurrent/RateLimiter.java
@@ -31,7 +31,7 @@
 import java.time.Duration;
 import java.util.Locale;
 import java.util.concurrent.TimeUnit;
-import org.checkerframework.checker.nullness.qual.Nullable;
+import javax.annotation.CheckForNull;
 
 /**
  * A rate limiter. Conceptually, a rate limiter distributes permits at a configurable rate. Each
@@ -94,6 +94,7 @@
 // would mean a maximum rate of "1MB/s", which might be small in some cases.
 @Beta
 @GwtIncompatible
+@ElementTypesAreNonnullByDefault
 public abstract class RateLimiter {
   /**
    * Creates a {@code RateLimiter} with the specified stable throughput, given as "permits per
@@ -214,7 +215,7 @@ static RateLimiter create(
   private final SleepingStopwatch stopwatch;
 
   // Can't be initialized in the constructor because mocks don't call the constructor.
-  private volatile @Nullable Object mutexDoNotUseDirectly;
+  @CheckForNull private volatile Object mutexDoNotUseDirectly;
 
   private Object mutex() {
     Object mutex = mutexDoNotUseDirectly;
diff --git a/guava/src/com/google/common/util/concurrent/Runnables.java b/guava/src/com/google/common/util/concurrent/Runnables.java
index e1ebd2389515..5503f68ae545 100644
--- a/guava/src/com/google/common/util/concurrent/Runnables.java
+++ b/guava/src/com/google/common/util/concurrent/Runnables.java
@@ -24,6 +24,7 @@
  */
 @Beta
 @GwtCompatible
+@ElementTypesAreNonnullByDefault
 public final class Runnables {
 
   private static final Runnable EMPTY_RUNNABLE =
diff --git a/guava/src/com/google/common/util/concurrent/SequentialExecutor.java b/guava/src/com/google/common/util/concurrent/SequentialExecutor.java
index 4fd50b94ee79..d0b600be840e 100644
--- a/guava/src/com/google/common/util/concurrent/SequentialExecutor.java
+++ b/guava/src/com/google/common/util/concurrent/SequentialExecutor.java
@@ -31,6 +31,7 @@
 import java.util.concurrent.RejectedExecutionException;
 import java.util.logging.Level;
 import java.util.logging.Logger;
+import javax.annotation.CheckForNull;
 
 /**
  * Executor ensuring that all Runnables submitted are executed in order, using the provided
@@ -47,6 +48,7 @@
  * restarted by a call to {@link #execute}.
  */
 @GwtIncompatible
+@ElementTypesAreNonnullByDefault
 final class SequentialExecutor implements Executor {
   private static final Logger log = Logger.getLogger(SequentialExecutor.class.getName());
 
@@ -94,10 +96,10 @@ enum WorkerRunningState {
    * execution of tasks will stop until a call to this method is made.
    */
   @Override
-  public void execute(final Runnable task) {
+  public void execute(Runnable task) {
     checkNotNull(task);
-    final Runnable submittedTask;
-    final long oldRunCount;
+    Runnable submittedTask;
+    long oldRunCount;
     synchronized (queue) {
       // If the worker is already running (or execute() on the delegate returned successfully, and
       // the worker has yet to start) then we don't need to start the worker.
@@ -170,7 +172,7 @@ public String toString() {
 
   /** Worker that runs tasks from {@link #queue} until it is empty. */
   private final class QueueWorker implements Runnable {
-    Runnable task;
+    @CheckForNull Runnable task;
 
     @Override
     public void run() {
diff --git a/guava/src/com/google/common/util/concurrent/Service.java b/guava/src/com/google/common/util/concurrent/Service.java
index 3c4c47628dec..dd0c7e6d947a 100644
--- a/guava/src/com/google/common/util/concurrent/Service.java
+++ b/guava/src/com/google/common/util/concurrent/Service.java
@@ -56,6 +56,7 @@
  */
 @DoNotMock("Create an AbstractIdleService")
 @GwtIncompatible
+@ElementTypesAreNonnullByDefault
 public interface Service {
   /**
    * If the service state is {@link State#NEW}, this initiates service startup and returns
@@ -206,61 +207,28 @@ default void awaitTerminated(Duration timeout) throws TimeoutException {
    */
   enum State {
     /** A service in this state is inactive. It does minimal work and consumes minimal resources. */
-    NEW {
-      @Override
-      boolean isTerminal() {
-        return false;
-      }
-    },
+    NEW,
 
     /** A service in this state is transitioning to {@link #RUNNING}. */
-    STARTING {
-      @Override
-      boolean isTerminal() {
-        return false;
-      }
-    },
+    STARTING,
 
     /** A service in this state is operational. */
-    RUNNING {
-      @Override
-      boolean isTerminal() {
-        return false;
-      }
-    },
+    RUNNING,
 
     /** A service in this state is transitioning to {@link #TERMINATED}. */
-    STOPPING {
-      @Override
-      boolean isTerminal() {
-        return false;
-      }
-    },
+    STOPPING,
 
     /**
      * A service in this state has completed execution normally. It does minimal work and consumes
      * minimal resources.
      */
-    TERMINATED {
-      @Override
-      boolean isTerminal() {
-        return true;
-      }
-    },
+    TERMINATED,
 
     /**
      * A service in this state has encountered a problem and may not be operational. It cannot be
      * started nor stopped.
      */
-    FAILED {
-      @Override
-      boolean isTerminal() {
-        return true;
-      }
-    };
-
-    /** Returns true if this state is terminal. */
-    abstract boolean isTerminal();
+    FAILED,
   }
 
   /**
diff --git a/guava/src/com/google/common/util/concurrent/ServiceManager.java b/guava/src/com/google/common/util/concurrent/ServiceManager.java
index e5b468f0a780..5ab95ffa6b74 100644
--- a/guava/src/com/google/common/util/concurrent/ServiceManager.java
+++ b/guava/src/com/google/common/util/concurrent/ServiceManager.java
@@ -51,6 +51,7 @@
 import com.google.common.util.concurrent.Service.State;
 import com.google.errorprone.annotations.CanIgnoreReturnValue;
 import com.google.errorprone.annotations.concurrent.GuardedBy;
+import com.google.j2objc.annotations.J2ObjCIncompatible;
 import com.google.j2objc.annotations.WeakOuter;
 import java.lang.ref.WeakReference;
 import java.time.Duration;
@@ -120,6 +121,7 @@
  * @since 14.0
  */
 @GwtIncompatible
+@ElementTypesAreNonnullByDefault
 public final class ServiceManager implements ServiceManagerBridge {
   private static final Logger logger = Logger.getLogger(ServiceManager.class.getName());
   private static final ListenerCallQueue.Event<Listener> HEALTHY_EVENT =
@@ -263,8 +265,7 @@ public void addListener(Listener listener, Executor executor) {
   @CanIgnoreReturnValue
   public ServiceManager startAsync() {
     for (Service service : services) {
-      State state = service.state();
-      checkState(state == NEW, "Service %s is %s, cannot start it.", service, state);
+      checkState(service.state() == NEW, "Not all services are NEW, cannot start %s", this);
     }
     for (Service service : services) {
       try {
@@ -413,6 +414,20 @@ public ImmutableMap<Service, Long> startupTimes() {
     return state.startupTimes();
   }
 
+  /**
+   * Returns the service load times. This value will only return startup times for services that
+   * have finished starting.
+   *
+   * @return Map of services and their corresponding startup time, the map entries will be ordered
+   *     by startup time.
+   * @since 31.0
+   */
+  @J2ObjCIncompatible
+  public ImmutableMap<Service, Duration> startupDurations() {
+    return ImmutableMap.copyOf(
+        Maps.<Service, Long, Duration>transformValues(startupTimes(), Duration::ofMillis));
+  }
+
   @Override
   public String toString() {
     return MoreObjects.toStringHelper(ServiceManager.class)
@@ -625,9 +640,9 @@ ImmutableMap<Service, Long> startupTimes() {
         // N.B. There will only be an entry in the map if the service has started
         for (Entry<Service, Stopwatch> entry : startupTimers.entrySet()) {
           Service service = entry.getKey();
-          Stopwatch stopWatch = entry.getValue();
-          if (!stopWatch.isRunning() && !(service instanceof NoOpService)) {
-            loadTimes.add(Maps.immutableEntry(service, stopWatch.elapsed(MILLISECONDS)));
+          Stopwatch stopwatch = entry.getValue();
+          if (!stopwatch.isRunning() && !(service instanceof NoOpService)) {
+            loadTimes.add(Maps.immutableEntry(service, stopwatch.elapsed(MILLISECONDS)));
           }
         }
       } finally {
diff --git a/guava/src/com/google/common/util/concurrent/ServiceManagerBridge.java b/guava/src/com/google/common/util/concurrent/ServiceManagerBridge.java
index a9300a616679..7ae430e3d251 100644
--- a/guava/src/com/google/common/util/concurrent/ServiceManagerBridge.java
+++ b/guava/src/com/google/common/util/concurrent/ServiceManagerBridge.java
@@ -26,6 +26,7 @@
  * {@code servicesByState()} to return {@code ImmutableMultimap}.
  */
 @GwtIncompatible
+@ElementTypesAreNonnullByDefault
 interface ServiceManagerBridge {
   ImmutableMultimap<State, Service> servicesByState();
 }
diff --git a/guava/src/com/google/common/util/concurrent/SettableFuture.java b/guava/src/com/google/common/util/concurrent/SettableFuture.java
index a0f47329027b..0a9e194657f8 100644
--- a/guava/src/com/google/common/util/concurrent/SettableFuture.java
+++ b/guava/src/com/google/common/util/concurrent/SettableFuture.java
@@ -33,17 +33,19 @@
  * @since 9.0 (in 1.0 as {@code ValueFuture})
  */
 @GwtCompatible
-public final class SettableFuture<V> extends AbstractFuture.TrustedFuture<V> {
+@ElementTypesAreNonnullByDefault
+public final class SettableFuture<V extends @Nullable Object>
+    extends AbstractFuture.TrustedFuture<V> {
   /**
    * Creates a new {@code SettableFuture} that can be completed or cancelled by a later method call.
    */
-  public static <V> SettableFuture<V> create() {
-    return new SettableFuture<V>();
+  public static <V extends @Nullable Object> SettableFuture<V> create() {
+    return new SettableFuture<>();
   }
 
   @CanIgnoreReturnValue
   @Override
-  public boolean set(@Nullable V value) {
+  public boolean set(@ParametricNullness V value) {
     return super.set(value);
   }
 
diff --git a/guava/src/com/google/common/util/concurrent/SimpleTimeLimiter.java b/guava/src/com/google/common/util/concurrent/SimpleTimeLimiter.java
index 9d0b81bce26a..c6ade6a3a0a5 100644
--- a/guava/src/com/google/common/util/concurrent/SimpleTimeLimiter.java
+++ b/guava/src/com/google/common/util/concurrent/SimpleTimeLimiter.java
@@ -34,6 +34,8 @@
 import java.util.concurrent.Future;
 import java.util.concurrent.TimeUnit;
 import java.util.concurrent.TimeoutException;
+import javax.annotation.CheckForNull;
+import org.checkerframework.checker.nullness.qual.Nullable;
 
 /**
  * A TimeLimiter that runs method calls in the background using an {@link ExecutorService}. If the
@@ -45,6 +47,7 @@
  */
 @Beta
 @GwtIncompatible
+@ElementTypesAreNonnullByDefault
 public final class SimpleTimeLimiter implements TimeLimiter {
 
   private final ExecutorService executor;
@@ -70,32 +73,27 @@ public static SimpleTimeLimiter create(ExecutorService executor) {
 
   @Override
   public <T> T newProxy(
-      final T target,
-      Class<T> interfaceType,
-      final long timeoutDuration,
-      final TimeUnit timeoutUnit) {
+      T target, Class<T> interfaceType, long timeoutDuration, TimeUnit timeoutUnit) {
     checkNotNull(target);
     checkNotNull(interfaceType);
     checkNotNull(timeoutUnit);
     checkPositiveTimeout(timeoutDuration);
     checkArgument(interfaceType.isInterface(), "interfaceType must be an interface type");
 
-    final Set<Method> interruptibleMethods = findInterruptibleMethods(interfaceType);
+    Set<Method> interruptibleMethods = findInterruptibleMethods(interfaceType);
 
     InvocationHandler handler =
         new InvocationHandler() {
           @Override
-          public Object invoke(Object obj, final Method method, final Object[] args)
+          @CheckForNull
+          public Object invoke(Object obj, Method method, @CheckForNull @Nullable Object[] args)
               throws Throwable {
-            Callable<Object> callable =
-                new Callable<Object>() {
-                  @Override
-                  public Object call() throws Exception {
-                    try {
-                      return method.invoke(target, args);
-                    } catch (InvocationTargetException e) {
-                      throw throwCause(e, false /* combineStackTraces */);
-                    }
+            Callable<@Nullable Object> callable =
+                () -> {
+                  try {
+                    return method.invoke(target, args);
+                  } catch (InvocationTargetException e) {
+                    throw throwCause(e, false /* combineStackTraces */);
                   }
                 };
             return callWithTimeout(
@@ -113,7 +111,7 @@ private static <T> T newProxy(Class<T> interfaceType, InvocationHandler handler)
     return interfaceType.cast(object);
   }
 
-  private <T> T callWithTimeout(
+  private <T extends @Nullable Object> T callWithTimeout(
       Callable<T> callable, long timeoutDuration, TimeUnit timeoutUnit, boolean amInterruptible)
       throws Exception {
     checkNotNull(callable);
@@ -143,7 +141,8 @@ private <T> T callWithTimeout(
 
   @CanIgnoreReturnValue
   @Override
-  public <T> T callWithTimeout(Callable<T> callable, long timeoutDuration, TimeUnit timeoutUnit)
+  public <T extends @Nullable Object> T callWithTimeout(
+      Callable<T> callable, long timeoutDuration, TimeUnit timeoutUnit)
       throws TimeoutException, InterruptedException, ExecutionException {
     checkNotNull(callable);
     checkNotNull(timeoutUnit);
@@ -164,7 +163,7 @@ public <T> T callWithTimeout(Callable<T> callable, long timeoutDuration, TimeUni
 
   @CanIgnoreReturnValue
   @Override
-  public <T> T callUninterruptiblyWithTimeout(
+  public <T extends @Nullable Object> T callUninterruptiblyWithTimeout(
       Callable<T> callable, long timeoutDuration, TimeUnit timeoutUnit)
       throws TimeoutException, ExecutionException {
     checkNotNull(callable);
diff --git a/guava/src/com/google/common/util/concurrent/SmoothRateLimiter.java b/guava/src/com/google/common/util/concurrent/SmoothRateLimiter.java
index d4b4aa11ee0c..ca78905908ed 100644
--- a/guava/src/com/google/common/util/concurrent/SmoothRateLimiter.java
+++ b/guava/src/com/google/common/util/concurrent/SmoothRateLimiter.java
@@ -22,6 +22,7 @@
 import java.util.concurrent.TimeUnit;
 
 @GwtIncompatible
+@ElementTypesAreNonnullByDefault
 abstract class SmoothRateLimiter extends RateLimiter {
   /*
    * How is the RateLimiter designed, and why?
diff --git a/guava/src/com/google/common/util/concurrent/Striped.java b/guava/src/com/google/common/util/concurrent/Striped.java
index c9ba77235d5a..2ea61cb3248a 100644
--- a/guava/src/com/google/common/util/concurrent/Striped.java
+++ b/guava/src/com/google/common/util/concurrent/Striped.java
@@ -14,6 +14,8 @@
 
 package com.google.common.util.concurrent;
 
+import static com.google.common.collect.Lists.newArrayList;
+
 import com.google.common.annotations.Beta;
 import com.google.common.annotations.GwtIncompatible;
 import com.google.common.annotations.VisibleForTesting;
@@ -21,7 +23,6 @@
 import com.google.common.base.Preconditions;
 import com.google.common.base.Supplier;
 import com.google.common.collect.ImmutableList;
-import com.google.common.collect.Iterables;
 import com.google.common.collect.MapMaker;
 import com.google.common.math.IntMath;
 import com.google.common.primitives.Ints;
@@ -40,6 +41,7 @@
 import java.util.concurrent.locks.ReadWriteLock;
 import java.util.concurrent.locks.ReentrantLock;
 import java.util.concurrent.locks.ReentrantReadWriteLock;
+import org.checkerframework.checker.nullness.qual.Nullable;
 
 /**
  * A striped {@code Lock/Semaphore/ReadWriteLock}. This offers the underlying lock striping similar
@@ -82,6 +84,7 @@
  */
 @Beta
 @GwtIncompatible
+@ElementTypesAreNonnullByDefault
 public abstract class Striped<L> {
   /**
    * If there are at least this many stripes, we assume the memory usage of a ConcurrentMap will be
@@ -136,26 +139,26 @@ private Striped() {}
    * @return the stripes corresponding to the objects (one per each object, derived by delegating to
    *     {@link #get(Object)}; may contain duplicates), in an increasing index order.
    */
-  public Iterable<L> bulkGet(Iterable<?> keys) {
-    // Initially using the array to store the keys, then reusing it to store the respective L's
-    final Object[] array = Iterables.toArray(keys, Object.class);
-    if (array.length == 0) {
+  public Iterable<L> bulkGet(Iterable<? extends Object> keys) {
+    // Initially using the list to store the keys, then reusing it to store the respective L's
+    List<Object> result = newArrayList(keys);
+    if (result.isEmpty()) {
       return ImmutableList.of();
     }
-    int[] stripes = new int[array.length];
-    for (int i = 0; i < array.length; i++) {
-      stripes[i] = indexFor(array[i]);
+    int[] stripes = new int[result.size()];
+    for (int i = 0; i < result.size(); i++) {
+      stripes[i] = indexFor(result.get(i));
     }
     Arrays.sort(stripes);
     // optimize for runs of identical stripes
     int previousStripe = stripes[0];
-    array[0] = getAt(previousStripe);
-    for (int i = 1; i < array.length; i++) {
+    result.set(0, getAt(previousStripe));
+    for (int i = 1; i < result.size(); i++) {
       int currentStripe = stripes[i];
       if (currentStripe == previousStripe) {
-        array[i] = array[i - 1];
+        result.set(i, result.get(i - 1));
       } else {
-        array[i] = getAt(currentStripe);
+        result.set(i, getAt(currentStripe));
         previousStripe = currentStripe;
       }
     }
@@ -177,8 +180,8 @@ public Iterable<L> bulkGet(Iterable<?> keys) {
      * be garbage collected after locking them, ending up in a huge mess.
      */
     @SuppressWarnings("unchecked") // we carefully replaced all keys with their respective L's
-    List<L> asList = (List<L>) Arrays.asList(array);
-    return Collections.unmodifiableList(asList);
+    List<L> asStripes = (List<L>) result;
+    return Collections.unmodifiableList(asStripes);
   }
 
   // Static factories
@@ -203,14 +206,7 @@ static <L> Striped<L> custom(int stripes, Supplier<L> supplier) {
    * @return a new {@code Striped<Lock>}
    */
   public static Striped<Lock> lock(int stripes) {
-    return custom(
-        stripes,
-        new Supplier<Lock>() {
-          @Override
-          public Lock get() {
-            return new PaddedLock();
-          }
-        });
+    return custom(stripes, PaddedLock::new);
   }
 
   /**
@@ -221,14 +217,7 @@ public Lock get() {
    * @return a new {@code Striped<Lock>}
    */
   public static Striped<Lock> lazyWeakLock(int stripes) {
-    return lazy(
-        stripes,
-        new Supplier<Lock>() {
-          @Override
-          public Lock get() {
-            return new ReentrantLock(false);
-          }
-        });
+    return lazy(stripes, () -> new ReentrantLock(false));
   }
 
   private static <L> Striped<L> lazy(int stripes, Supplier<L> supplier) {
@@ -245,15 +234,8 @@ private static <L> Striped<L> lazy(int stripes, Supplier<L> supplier) {
    * @param permits the number of permits in each semaphore
    * @return a new {@code Striped<Semaphore>}
    */
-  public static Striped<Semaphore> semaphore(int stripes, final int permits) {
-    return custom(
-        stripes,
-        new Supplier<Semaphore>() {
-          @Override
-          public Semaphore get() {
-            return new PaddedSemaphore(permits);
-          }
-        });
+  public static Striped<Semaphore> semaphore(int stripes, int permits) {
+    return custom(stripes, () -> new PaddedSemaphore(permits));
   }
 
   /**
@@ -264,15 +246,8 @@ public Semaphore get() {
    * @param permits the number of permits in each semaphore
    * @return a new {@code Striped<Semaphore>}
    */
-  public static Striped<Semaphore> lazyWeakSemaphore(int stripes, final int permits) {
-    return lazy(
-        stripes,
-        new Supplier<Semaphore>() {
-          @Override
-          public Semaphore get() {
-            return new Semaphore(permits, false);
-          }
-        });
+  public static Striped<Semaphore> lazyWeakSemaphore(int stripes, int permits) {
+    return lazy(stripes, () -> new Semaphore(permits, false));
   }
 
   /**
@@ -283,7 +258,7 @@ public Semaphore get() {
    * @return a new {@code Striped<ReadWriteLock>}
    */
   public static Striped<ReadWriteLock> readWriteLock(int stripes) {
-    return custom(stripes, READ_WRITE_LOCK_SUPPLIER);
+    return custom(stripes, ReentrantReadWriteLock::new);
   }
 
   /**
@@ -294,25 +269,8 @@ public static Striped<ReadWriteLock> readWriteLock(int stripes) {
    * @return a new {@code Striped<ReadWriteLock>}
    */
   public static Striped<ReadWriteLock> lazyWeakReadWriteLock(int stripes) {
-    return lazy(stripes, WEAK_SAFE_READ_WRITE_LOCK_SUPPLIER);
+    return lazy(stripes, WeakSafeReadWriteLock::new);
   }
-
-  private static final Supplier<ReadWriteLock> READ_WRITE_LOCK_SUPPLIER =
-      new Supplier<ReadWriteLock>() {
-        @Override
-        public ReadWriteLock get() {
-          return new ReentrantReadWriteLock();
-        }
-      };
-
-  private static final Supplier<ReadWriteLock> WEAK_SAFE_READ_WRITE_LOCK_SUPPLIER =
-      new Supplier<ReadWriteLock>() {
-        @Override
-        public ReadWriteLock get() {
-          return new WeakSafeReadWriteLock();
-        }
-      };
-
   /**
    * ReadWriteLock implementation whose read and write locks retain a reference back to this lock.
    * Otherwise, a reference to just the read lock or just the write lock would not suffice to ensure
@@ -435,10 +393,10 @@ public int size() {
    */
   @VisibleForTesting
   static class SmallLazyStriped<L> extends PowerOfTwoStriped<L> {
-    final AtomicReferenceArray<ArrayReference<? extends L>> locks;
+    final AtomicReferenceArray<@Nullable ArrayReference<? extends L>> locks;
     final Supplier<L> supplier;
     final int size;
-    final ReferenceQueue<L> queue = new ReferenceQueue<L>();
+    final ReferenceQueue<L> queue = new ReferenceQueue<>();
 
     SmallLazyStriped(int stripes, Supplier<L> supplier) {
       super(stripes);
@@ -458,7 +416,7 @@ public L getAt(int index) {
         return existing;
       }
       L created = supplier.get();
-      ArrayReference<L> newRef = new ArrayReference<L>(created, index, queue);
+      ArrayReference<L> newRef = new ArrayReference<>(created, index, queue);
       while (!locks.compareAndSet(index, existingRef, newRef)) {
         // we raced, we need to re-read and try again
         existingRef = locks.get(index);
diff --git a/guava/src/com/google/common/util/concurrent/ThreadFactoryBuilder.java b/guava/src/com/google/common/util/concurrent/ThreadFactoryBuilder.java
index f09ed4e71721..de7236369d25 100644
--- a/guava/src/com/google/common/util/concurrent/ThreadFactoryBuilder.java
+++ b/guava/src/com/google/common/util/concurrent/ThreadFactoryBuilder.java
@@ -16,6 +16,7 @@
 
 import static com.google.common.base.Preconditions.checkArgument;
 import static com.google.common.base.Preconditions.checkNotNull;
+import static java.util.Objects.requireNonNull;
 
 import com.google.common.annotations.GwtIncompatible;
 import com.google.errorprone.annotations.CanIgnoreReturnValue;
@@ -25,6 +26,10 @@
 import java.util.concurrent.Executors;
 import java.util.concurrent.ThreadFactory;
 import java.util.concurrent.atomic.AtomicLong;
+import javax.annotation.CheckForNull;
+import org.checkerframework.checker.formatter.qual.ConversionCategory;
+import org.checkerframework.checker.formatter.qual.Format;
+import org.checkerframework.checker.formatter.qual.FormatMethod;
 
 /**
  * A ThreadFactory builder, providing any combination of these features:
@@ -45,12 +50,13 @@
  */
 @CanIgnoreReturnValue
 @GwtIncompatible
+@ElementTypesAreNonnullByDefault
 public final class ThreadFactoryBuilder {
-  private String nameFormat = null;
-  private Boolean daemon = null;
-  private Integer priority = null;
-  private UncaughtExceptionHandler uncaughtExceptionHandler = null;
-  private ThreadFactory backingThreadFactory = null;
+  @CheckForNull private @Format({ConversionCategory.INT}) String nameFormat = null;
+  @CheckForNull private Boolean daemon = null;
+  @CheckForNull private Integer priority = null;
+  @CheckForNull private UncaughtExceptionHandler uncaughtExceptionHandler = null;
+  @CheckForNull private ThreadFactory backingThreadFactory = null;
 
   /** Creates a new {@link ThreadFactory} builder. */
   public ThreadFactoryBuilder() {}
@@ -66,7 +72,7 @@ public ThreadFactoryBuilder() {}
    *     "rpc-pool-1"}, {@code "rpc-pool-2"}, etc.
    * @return this for the builder pattern
    */
-  public ThreadFactoryBuilder setNameFormat(String nameFormat) {
+  public ThreadFactoryBuilder setNameFormat(@Format({ConversionCategory.INT}) String nameFormat) {
     String unused = format(nameFormat, 0); // fail fast if the format is bad or null
     this.nameFormat = nameFormat;
     return this;
@@ -148,21 +154,22 @@ public ThreadFactory build() {
   // Split out so that the anonymous ThreadFactory can't contain a reference back to the builder.
   // At least, I assume that's why. TODO(cpovirk): Check, and maybe add a test for this.
   private static ThreadFactory doBuild(ThreadFactoryBuilder builder) {
-    final String nameFormat = builder.nameFormat;
-    final Boolean daemon = builder.daemon;
-    final Integer priority = builder.priority;
-    final UncaughtExceptionHandler uncaughtExceptionHandler = builder.uncaughtExceptionHandler;
-    final ThreadFactory backingThreadFactory =
+    @Format({ConversionCategory.INT}) String nameFormat = builder.nameFormat;
+    Boolean daemon = builder.daemon;
+    Integer priority = builder.priority;
+    UncaughtExceptionHandler uncaughtExceptionHandler = builder.uncaughtExceptionHandler;
+    ThreadFactory backingThreadFactory =
         (builder.backingThreadFactory != null)
             ? builder.backingThreadFactory
             : Executors.defaultThreadFactory();
-    final AtomicLong count = (nameFormat != null) ? new AtomicLong(0) : null;
+    AtomicLong count = (nameFormat != null) ? new AtomicLong(0) : null;
     return new ThreadFactory() {
       @Override
       public Thread newThread(Runnable runnable) {
         Thread thread = backingThreadFactory.newThread(runnable);
         if (nameFormat != null) {
-          thread.setName(format(nameFormat, count.getAndIncrement()));
+          // requireNonNull is safe because we create `count` if (and only if) we have a nameFormat.
+          thread.setName(format(nameFormat, requireNonNull(count).getAndIncrement()));
         }
         if (daemon != null) {
           thread.setDaemon(daemon);
@@ -178,6 +185,7 @@ public Thread newThread(Runnable runnable) {
     };
   }
 
+  @FormatMethod
   private static String format(String format, Object... args) {
     return String.format(Locale.ROOT, format, args);
   }
diff --git a/guava/src/com/google/common/util/concurrent/TimeLimiter.java b/guava/src/com/google/common/util/concurrent/TimeLimiter.java
index 600c6cf58f5d..0245fec3ca87 100644
--- a/guava/src/com/google/common/util/concurrent/TimeLimiter.java
+++ b/guava/src/com/google/common/util/concurrent/TimeLimiter.java
@@ -25,6 +25,7 @@
 import java.util.concurrent.ExecutionException;
 import java.util.concurrent.TimeUnit;
 import java.util.concurrent.TimeoutException;
+import org.checkerframework.checker.nullness.qual.Nullable;
 
 /**
  * Imposes a time limit on method calls.
@@ -36,6 +37,7 @@
 @Beta
 @DoNotMock("Use FakeTimeLimiter")
 @GwtIncompatible
+@ElementTypesAreNonnullByDefault
 public interface TimeLimiter {
 
   /**
@@ -144,7 +146,8 @@ default <T> T newProxy(T target, Class<T> interfaceType, Duration timeout) {
    */
   @SuppressWarnings("GoodTime") // should accept a java.time.Duration
   @CanIgnoreReturnValue
-  <T> T callWithTimeout(Callable<T> callable, long timeoutDuration, TimeUnit timeoutUnit)
+  <T extends @Nullable Object> T callWithTimeout(
+      Callable<T> callable, long timeoutDuration, TimeUnit timeoutUnit)
       throws TimeoutException, InterruptedException, ExecutionException;
 
   /**
@@ -164,7 +167,7 @@ <T> T callWithTimeout(Callable<T> callable, long timeoutDuration, TimeUnit timeo
    * @since 28.0
    */
   @CanIgnoreReturnValue
-  default <T> T callWithTimeout(Callable<T> callable, Duration timeout)
+  default <T extends @Nullable Object> T callWithTimeout(Callable<T> callable, Duration timeout)
       throws TimeoutException, InterruptedException, ExecutionException {
     return callWithTimeout(callable, toNanosSaturated(timeout), TimeUnit.NANOSECONDS);
   }
@@ -190,7 +193,7 @@ default <T> T callWithTimeout(Callable<T> callable, Duration timeout)
    */
   @SuppressWarnings("GoodTime") // should accept a java.time.Duration
   @CanIgnoreReturnValue
-  <T> T callUninterruptiblyWithTimeout(
+  <T extends @Nullable Object> T callUninterruptiblyWithTimeout(
       Callable<T> callable, long timeoutDuration, TimeUnit timeoutUnit)
       throws TimeoutException, ExecutionException;
 
@@ -213,8 +216,8 @@ <T> T callUninterruptiblyWithTimeout(
    * @since 28.0
    */
   @CanIgnoreReturnValue
-  default <T> T callUninterruptiblyWithTimeout(Callable<T> callable, Duration timeout)
-      throws TimeoutException, ExecutionException {
+  default <T extends @Nullable Object> T callUninterruptiblyWithTimeout(
+      Callable<T> callable, Duration timeout) throws TimeoutException, ExecutionException {
     return callUninterruptiblyWithTimeout(
         callable, toNanosSaturated(timeout), TimeUnit.NANOSECONDS);
   }
diff --git a/guava/src/com/google/common/util/concurrent/TimeoutFuture.java b/guava/src/com/google/common/util/concurrent/TimeoutFuture.java
index af30d1f0a445..ed8a7bfdbe70 100644
--- a/guava/src/com/google/common/util/concurrent/TimeoutFuture.java
+++ b/guava/src/com/google/common/util/concurrent/TimeoutFuture.java
@@ -24,6 +24,7 @@
 import java.util.concurrent.ScheduledFuture;
 import java.util.concurrent.TimeUnit;
 import java.util.concurrent.TimeoutException;
+import javax.annotation.CheckForNull;
 import org.checkerframework.checker.nullness.qual.Nullable;
 
 /**
@@ -34,8 +35,9 @@
  * interrupted and cancelled if it times out.
  */
 @GwtIncompatible
-final class TimeoutFuture<V> extends FluentFuture.TrustedFuture<V> {
-  static <V> ListenableFuture<V> create(
+@ElementTypesAreNonnullByDefault
+final class TimeoutFuture<V extends @Nullable Object> extends FluentFuture.TrustedFuture<V> {
+  static <V extends @Nullable Object> ListenableFuture<V> create(
       ListenableFuture<V> delegate,
       long time,
       TimeUnit unit,
@@ -71,16 +73,16 @@ static <V> ListenableFuture<V> create(
    * write-barriers).
    */
 
-  private @Nullable ListenableFuture<V> delegateRef;
-  private @Nullable ScheduledFuture<?> timer;
+  @CheckForNull private ListenableFuture<V> delegateRef;
+  @CheckForNull private ScheduledFuture<?> timer;
 
   private TimeoutFuture(ListenableFuture<V> delegate) {
     this.delegateRef = Preconditions.checkNotNull(delegate);
   }
 
   /** A runnable that is called when the delegate or the timer completes. */
-  private static final class Fire<V> implements Runnable {
-    @Nullable TimeoutFuture<V> timeoutFutureRef;
+  private static final class Fire<V extends @Nullable Object> implements Runnable {
+    @CheckForNull TimeoutFuture<V> timeoutFutureRef;
 
     Fire(TimeoutFuture<V> timeoutFuture) {
       this.timeoutFutureRef = timeoutFuture;
@@ -152,13 +154,14 @@ public synchronized Throwable fillInStackTrace() {
   }
 
   @Override
+  @CheckForNull
   protected String pendingToString() {
     ListenableFuture<? extends V> localInputFuture = delegateRef;
     ScheduledFuture<?> localTimer = timer;
     if (localInputFuture != null) {
       String message = "inputFuture=[" + localInputFuture + "]";
       if (localTimer != null) {
-        final long delay = localTimer.getDelay(TimeUnit.MILLISECONDS);
+        long delay = localTimer.getDelay(TimeUnit.MILLISECONDS);
         // Negative delays look confusing in an error message
         if (delay > 0) {
           message += ", remaining delay=[" + delay + " ms]";
diff --git a/guava/src/com/google/common/util/concurrent/TrustedListenableFutureTask.java b/guava/src/com/google/common/util/concurrent/TrustedListenableFutureTask.java
index 3a607c5b615f..929c9fb1ea23 100644
--- a/guava/src/com/google/common/util/concurrent/TrustedListenableFutureTask.java
+++ b/guava/src/com/google/common/util/concurrent/TrustedListenableFutureTask.java
@@ -21,6 +21,7 @@
 import java.util.concurrent.Callable;
 import java.util.concurrent.Executors;
 import java.util.concurrent.RunnableFuture;
+import javax.annotation.CheckForNull;
 import org.checkerframework.checker.nullness.qual.Nullable;
 
 /**
@@ -30,15 +31,17 @@
  * performance reasons.
  */
 @GwtCompatible
-class TrustedListenableFutureTask<V> extends FluentFuture.TrustedFuture<V>
+@ElementTypesAreNonnullByDefault
+class TrustedListenableFutureTask<V extends @Nullable Object> extends FluentFuture.TrustedFuture<V>
     implements RunnableFuture<V> {
 
-  static <V> TrustedListenableFutureTask<V> create(AsyncCallable<V> callable) {
-    return new TrustedListenableFutureTask<V>(callable);
+  static <V extends @Nullable Object> TrustedListenableFutureTask<V> create(
+      AsyncCallable<V> callable) {
+    return new TrustedListenableFutureTask<>(callable);
   }
 
-  static <V> TrustedListenableFutureTask<V> create(Callable<V> callable) {
-    return new TrustedListenableFutureTask<V>(callable);
+  static <V extends @Nullable Object> TrustedListenableFutureTask<V> create(Callable<V> callable) {
+    return new TrustedListenableFutureTask<>(callable);
   }
 
   /**
@@ -50,8 +53,9 @@ static <V> TrustedListenableFutureTask<V> create(Callable<V> callable) {
    *     result, consider using constructions of the form: {@code ListenableFuture<?> f =
    *     ListenableFutureTask.create(runnable, null)}
    */
-  static <V> TrustedListenableFutureTask<V> create(Runnable runnable, @Nullable V result) {
-    return new TrustedListenableFutureTask<V>(Executors.callable(runnable, result));
+  static <V extends @Nullable Object> TrustedListenableFutureTask<V> create(
+      Runnable runnable, @ParametricNullness V result) {
+    return new TrustedListenableFutureTask<>(Executors.callable(runnable, result));
   }
 
   /*
@@ -61,7 +65,7 @@ static <V> TrustedListenableFutureTask<V> create(Runnable runnable, @Nullable V
    * <p>{@code volatile} is required for j2objc transpiling:
    * https://developers.google.com/j2objc/guides/j2objc-memory-model#atomicity
    */
-  private volatile InterruptibleTask<?> task;
+  @CheckForNull private volatile InterruptibleTask<?> task;
 
   TrustedListenableFutureTask(Callable<V> callable) {
     this.task = new TrustedFutureInterruptibleTask(callable);
@@ -73,7 +77,7 @@ static <V> TrustedListenableFutureTask<V> create(Runnable runnable, @Nullable V
 
   @Override
   public void run() {
-    InterruptibleTask localTask = task;
+    InterruptibleTask<?> localTask = task;
     if (localTask != null) {
       localTask.run();
     }
@@ -89,7 +93,7 @@ protected void afterDone() {
     super.afterDone();
 
     if (wasInterrupted()) {
-      InterruptibleTask localTask = task;
+      InterruptibleTask<?> localTask = task;
       if (localTask != null) {
         localTask.interruptTask();
       }
@@ -99,8 +103,9 @@ protected void afterDone() {
   }
 
   @Override
+  @CheckForNull
   protected String pendingToString() {
-    InterruptibleTask localTask = task;
+    InterruptibleTask<?> localTask = task;
     if (localTask != null) {
       return "task=[" + localTask + "]";
     }
@@ -121,17 +126,19 @@ final boolean isDone() {
     }
 
     @Override
+    @ParametricNullness
     V runInterruptibly() throws Exception {
       return callable.call();
     }
 
     @Override
-    void afterRanInterruptibly(V result, Throwable error) {
-      if (error == null) {
-        TrustedListenableFutureTask.this.set(result);
-      } else {
-        setException(error);
-      }
+    void afterRanInterruptiblySuccess(@ParametricNullness V result) {
+      TrustedListenableFutureTask.this.set(result);
+    }
+
+    @Override
+    void afterRanInterruptiblyFailure(Throwable error) {
+      setException(error);
     }
 
     @Override
@@ -164,12 +171,13 @@ ListenableFuture<V> runInterruptibly() throws Exception {
     }
 
     @Override
-    void afterRanInterruptibly(ListenableFuture<V> result, Throwable error) {
-      if (error == null) {
-        setFuture(result);
-      } else {
-        setException(error);
-      }
+    void afterRanInterruptiblySuccess(ListenableFuture<V> result) {
+      setFuture(result);
+    }
+
+    @Override
+    void afterRanInterruptiblyFailure(Throwable error) {
+      setException(error);
     }
 
     @Override
diff --git a/guava/src/com/google/common/util/concurrent/UncaughtExceptionHandlers.java b/guava/src/com/google/common/util/concurrent/UncaughtExceptionHandlers.java
index c0c26006e1fd..a1add8bcbb30 100644
--- a/guava/src/com/google/common/util/concurrent/UncaughtExceptionHandlers.java
+++ b/guava/src/com/google/common/util/concurrent/UncaughtExceptionHandlers.java
@@ -29,6 +29,7 @@
  * @since 8.0
  */
 @GwtIncompatible
+@ElementTypesAreNonnullByDefault
 public final class UncaughtExceptionHandlers {
   private UncaughtExceptionHandlers() {}
 
diff --git a/guava/src/com/google/common/util/concurrent/UncheckedExecutionException.java b/guava/src/com/google/common/util/concurrent/UncheckedExecutionException.java
index c6c57d3b71d8..713f4a69e78d 100644
--- a/guava/src/com/google/common/util/concurrent/UncheckedExecutionException.java
+++ b/guava/src/com/google/common/util/concurrent/UncheckedExecutionException.java
@@ -15,7 +15,7 @@
 package com.google.common.util.concurrent;
 
 import com.google.common.annotations.GwtCompatible;
-import org.checkerframework.checker.nullness.qual.Nullable;
+import javax.annotation.CheckForNull;
 
 /**
  * Unchecked variant of {@link java.util.concurrent.ExecutionException}. As with {@code
@@ -33,22 +33,29 @@
  * @since 10.0
  */
 @GwtCompatible
+@ElementTypesAreNonnullByDefault
 public class UncheckedExecutionException extends RuntimeException {
+  /*
+   * Ideally, this class would have exposed only constructors that require a non-null cause. We
+   * might try to move in that direction, but there are complications. See
+   * https://github.com/jspecify/nullness-checker-for-checker-framework/blob/61aafa4ae52594830cfc2d61c8b113009dbdb045/src/main/java/com/google/jspecify/nullness/NullSpecTransfer.java#L789
+   */
+
   /** Creates a new instance with {@code null} as its detail message. */
   protected UncheckedExecutionException() {}
 
   /** Creates a new instance with the given detail message. */
-  protected UncheckedExecutionException(@Nullable String message) {
+  protected UncheckedExecutionException(@CheckForNull String message) {
     super(message);
   }
 
   /** Creates a new instance with the given detail message and cause. */
-  public UncheckedExecutionException(@Nullable String message, @Nullable Throwable cause) {
+  public UncheckedExecutionException(@CheckForNull String message, @CheckForNull Throwable cause) {
     super(message, cause);
   }
 
   /** Creates a new instance with the given cause. */
-  public UncheckedExecutionException(@Nullable Throwable cause) {
+  public UncheckedExecutionException(@CheckForNull Throwable cause) {
     super(cause);
   }
 
diff --git a/guava/src/com/google/common/util/concurrent/UncheckedTimeoutException.java b/guava/src/com/google/common/util/concurrent/UncheckedTimeoutException.java
index 04fddf451d52..8e30fca37fd1 100644
--- a/guava/src/com/google/common/util/concurrent/UncheckedTimeoutException.java
+++ b/guava/src/com/google/common/util/concurrent/UncheckedTimeoutException.java
@@ -15,7 +15,7 @@
 package com.google.common.util.concurrent;
 
 import com.google.common.annotations.GwtIncompatible;
-import org.checkerframework.checker.nullness.qual.Nullable;
+import javax.annotation.CheckForNull;
 
 /**
  * Unchecked version of {@link java.util.concurrent.TimeoutException}.
@@ -24,18 +24,19 @@
  * @since 1.0
  */
 @GwtIncompatible
+@ElementTypesAreNonnullByDefault
 public class UncheckedTimeoutException extends RuntimeException {
   public UncheckedTimeoutException() {}
 
-  public UncheckedTimeoutException(@Nullable String message) {
+  public UncheckedTimeoutException(@CheckForNull String message) {
     super(message);
   }
 
-  public UncheckedTimeoutException(@Nullable Throwable cause) {
+  public UncheckedTimeoutException(@CheckForNull Throwable cause) {
     super(cause);
   }
 
-  public UncheckedTimeoutException(@Nullable String message, @Nullable Throwable cause) {
+  public UncheckedTimeoutException(@CheckForNull String message, @CheckForNull Throwable cause) {
     super(message, cause);
   }
 
diff --git a/guava/src/com/google/common/util/concurrent/Uninterruptibles.java b/guava/src/com/google/common/util/concurrent/Uninterruptibles.java
index 0ce6f1ad3018..09ace92fae75 100644
--- a/guava/src/com/google/common/util/concurrent/Uninterruptibles.java
+++ b/guava/src/com/google/common/util/concurrent/Uninterruptibles.java
@@ -18,7 +18,6 @@
 import static com.google.common.util.concurrent.Internal.toNanosSaturated;
 import static java.util.concurrent.TimeUnit.NANOSECONDS;
 
-import com.google.common.annotations.Beta;
 import com.google.common.annotations.GwtCompatible;
 import com.google.common.annotations.GwtIncompatible;
 import com.google.common.base.Preconditions;
@@ -35,6 +34,7 @@
 import java.util.concurrent.TimeoutException;
 import java.util.concurrent.locks.Condition;
 import java.util.concurrent.locks.Lock;
+import org.checkerframework.checker.nullness.qual.Nullable;
 
 /**
  * Utilities for treating interruptible operations as uninterruptible. In all cases, if a thread is
@@ -45,6 +45,7 @@
  * @since 10.0
  */
 @GwtCompatible(emulated = true)
+@ElementTypesAreNonnullByDefault
 public final class Uninterruptibles {
 
   // Implementation Note: As of 3-7-11, the logic for each blocking/timeout
@@ -78,7 +79,6 @@ public static void awaitUninterruptibly(CountDownLatch latch) {
    */
   @CanIgnoreReturnValue // TODO(cpovirk): Consider being more strict.
   @GwtIncompatible // concurrency
-  @Beta
   public static boolean awaitUninterruptibly(CountDownLatch latch, Duration timeout) {
     return awaitUninterruptibly(latch, toNanosSaturated(timeout), TimeUnit.NANOSECONDS);
   }
@@ -119,7 +119,6 @@ public static boolean awaitUninterruptibly(CountDownLatch latch, long timeout, T
    * @since 28.0
    */
   @GwtIncompatible // concurrency
-  @Beta
   public static boolean awaitUninterruptibly(Condition condition, Duration timeout) {
     return awaitUninterruptibly(condition, toNanosSaturated(timeout), TimeUnit.NANOSECONDS);
   }
@@ -180,7 +179,6 @@ public static void joinUninterruptibly(Thread toJoin) {
    * @since 28.0
    */
   @GwtIncompatible // concurrency
-  @Beta
   public static void joinUninterruptibly(Thread toJoin, Duration timeout) {
     joinUninterruptibly(toJoin, toNanosSaturated(timeout), TimeUnit.NANOSECONDS);
   }
@@ -232,7 +230,9 @@ public static void joinUninterruptibly(Thread toJoin, long timeout, TimeUnit uni
    * @throws CancellationException if the computation was cancelled
    */
   @CanIgnoreReturnValue
-  public static <V> V getUninterruptibly(Future<V> future) throws ExecutionException {
+  @ParametricNullness
+  public static <V extends @Nullable Object> V getUninterruptibly(Future<V> future)
+      throws ExecutionException {
     boolean interrupted = false;
     try {
       while (true) {
@@ -270,9 +270,9 @@ public static <V> V getUninterruptibly(Future<V> future) throws ExecutionExcepti
    */
   @CanIgnoreReturnValue
   @GwtIncompatible // java.time.Duration
-  @Beta
-  public static <V> V getUninterruptibly(Future<V> future, Duration timeout)
-      throws ExecutionException, TimeoutException {
+  @ParametricNullness
+  public static <V extends @Nullable Object> V getUninterruptibly(
+      Future<V> future, Duration timeout) throws ExecutionException, TimeoutException {
     return getUninterruptibly(future, toNanosSaturated(timeout), TimeUnit.NANOSECONDS);
   }
 
@@ -297,8 +297,9 @@ public static <V> V getUninterruptibly(Future<V> future, Duration timeout)
   @CanIgnoreReturnValue
   @GwtIncompatible // TODO
   @SuppressWarnings("GoodTime") // should accept a java.time.Duration
-  public static <V> V getUninterruptibly(Future<V> future, long timeout, TimeUnit unit)
-      throws ExecutionException, TimeoutException {
+  @ParametricNullness
+  public static <V extends @Nullable Object> V getUninterruptibly(
+      Future<V> future, long timeout, TimeUnit unit) throws ExecutionException, TimeoutException {
     boolean interrupted = false;
     try {
       long remainingNanos = unit.toNanos(timeout);
@@ -373,7 +374,6 @@ public static <E> void putUninterruptibly(BlockingQueue<E> queue, E element) {
    * @since 28.0
    */
   @GwtIncompatible // concurrency
-  @Beta
   public static void sleepUninterruptibly(Duration sleepFor) {
     sleepUninterruptibly(toNanosSaturated(sleepFor), TimeUnit.NANOSECONDS);
   }
@@ -411,7 +411,6 @@ public static void sleepUninterruptibly(long sleepFor, TimeUnit unit) {
    * @since 28.0
    */
   @GwtIncompatible // concurrency
-  @Beta
   public static boolean tryAcquireUninterruptibly(Semaphore semaphore, Duration timeout) {
     return tryAcquireUninterruptibly(semaphore, toNanosSaturated(timeout), TimeUnit.NANOSECONDS);
   }
@@ -436,7 +435,6 @@ public static boolean tryAcquireUninterruptibly(
    * @since 28.0
    */
   @GwtIncompatible // concurrency
-  @Beta
   public static boolean tryAcquireUninterruptibly(
       Semaphore semaphore, int permits, Duration timeout) {
     return tryAcquireUninterruptibly(
@@ -481,7 +479,6 @@ public static boolean tryAcquireUninterruptibly(
    * @since 30.0
    */
   @GwtIncompatible // concurrency
-  @Beta
   public static boolean tryLockUninterruptibly(Lock lock, Duration timeout) {
     return tryLockUninterruptibly(lock, toNanosSaturated(timeout), TimeUnit.NANOSECONDS);
   }
@@ -521,7 +518,6 @@ public static boolean tryLockUninterruptibly(Lock lock, long timeout, TimeUnit u
    *
    * @since 30.0
    */
-  @Beta
   @GwtIncompatible // concurrency
   public static void awaitTerminationUninterruptibly(ExecutorService executor) {
     // TODO(cpovirk): We could optimize this to avoid calling nanoTime() at all.
@@ -534,7 +530,6 @@ public static void awaitTerminationUninterruptibly(ExecutorService executor) {
    *
    * @since 30.0
    */
-  @Beta
   @GwtIncompatible // concurrency
   public static boolean awaitTerminationUninterruptibly(
       ExecutorService executor, Duration timeout) {
@@ -547,7 +542,6 @@ public static boolean awaitTerminationUninterruptibly(
    *
    * @since 30.0
    */
-  @Beta
   @GwtIncompatible // concurrency
   @SuppressWarnings("GoodTime")
   public static boolean awaitTerminationUninterruptibly(
diff --git a/guava/src/com/google/common/util/concurrent/WrappingExecutorService.java b/guava/src/com/google/common/util/concurrent/WrappingExecutorService.java
index 217e0a770fee..5a3c3927a6b9 100644
--- a/guava/src/com/google/common/util/concurrent/WrappingExecutorService.java
+++ b/guava/src/com/google/common/util/concurrent/WrappingExecutorService.java
@@ -29,6 +29,7 @@
 import java.util.concurrent.Future;
 import java.util.concurrent.TimeUnit;
 import java.util.concurrent.TimeoutException;
+import org.checkerframework.checker.nullness.qual.Nullable;
 
 /**
  * An abstract {@code ExecutorService} that allows subclasses to {@linkplain #wrapTask(Callable)
@@ -42,6 +43,7 @@
  */
 @CanIgnoreReturnValue // TODO(cpovirk): Consider being more strict.
 @GwtIncompatible
+@ElementTypesAreNonnullByDefault
 abstract class WrappingExecutorService implements ExecutorService {
   private final ExecutorService delegate;
 
@@ -53,23 +55,20 @@ protected WrappingExecutorService(ExecutorService delegate) {
    * Wraps a {@code Callable} for submission to the underlying executor. This method is also applied
    * to any {@code Runnable} passed to the default implementation of {@link #wrapTask(Runnable)}.
    */
-  protected abstract <T> Callable<T> wrapTask(Callable<T> callable);
+  protected abstract <T extends @Nullable Object> Callable<T> wrapTask(Callable<T> callable);
 
   /**
    * Wraps a {@code Runnable} for submission to the underlying executor. The default implementation
    * delegates to {@link #wrapTask(Callable)}.
    */
   protected Runnable wrapTask(Runnable command) {
-    final Callable<Object> wrapped = wrapTask(Executors.callable(command, null));
-    return new Runnable() {
-      @Override
-      public void run() {
-        try {
-          wrapped.call();
-        } catch (Exception e) {
-          throwIfUnchecked(e);
-          throw new RuntimeException(e);
-        }
+    Callable<Object> wrapped = wrapTask(Executors.callable(command, null));
+    return () -> {
+      try {
+        wrapped.call();
+      } catch (Exception e) {
+        throwIfUnchecked(e);
+        throw new RuntimeException(e);
       }
     };
   }
@@ -79,7 +78,8 @@ public void run() {
    *
    * @throws NullPointerException if any element of {@code tasks} is null
    */
-  private <T> ImmutableList<Callable<T>> wrapTasks(Collection<? extends Callable<T>> tasks) {
+  private <T extends @Nullable Object> ImmutableList<Callable<T>> wrapTasks(
+      Collection<? extends Callable<T>> tasks) {
     ImmutableList.Builder<Callable<T>> builder = ImmutableList.builder();
     for (Callable<T> task : tasks) {
       builder.add(wrapTask(task));
@@ -94,7 +94,7 @@ public final void execute(Runnable command) {
   }
 
   @Override
-  public final <T> Future<T> submit(Callable<T> task) {
+  public final <T extends @Nullable Object> Future<T> submit(Callable<T> task) {
     return delegate.submit(wrapTask(checkNotNull(task)));
   }
 
@@ -104,31 +104,33 @@ public final Future<?> submit(Runnable task) {
   }
 
   @Override
-  public final <T> Future<T> submit(Runnable task, T result) {
+  public final <T extends @Nullable Object> Future<T> submit(
+      Runnable task, @ParametricNullness T result) {
     return delegate.submit(wrapTask(task), result);
   }
 
   @Override
-  public final <T> List<Future<T>> invokeAll(Collection<? extends Callable<T>> tasks)
-      throws InterruptedException {
+  public final <T extends @Nullable Object> List<Future<T>> invokeAll(
+      Collection<? extends Callable<T>> tasks) throws InterruptedException {
     return delegate.invokeAll(wrapTasks(tasks));
   }
 
   @Override
-  public final <T> List<Future<T>> invokeAll(
+  public final <T extends @Nullable Object> List<Future<T>> invokeAll(
       Collection<? extends Callable<T>> tasks, long timeout, TimeUnit unit)
       throws InterruptedException {
     return delegate.invokeAll(wrapTasks(tasks), timeout, unit);
   }
 
   @Override
-  public final <T> T invokeAny(Collection<? extends Callable<T>> tasks)
+  public final <T extends @Nullable Object> T invokeAny(Collection<? extends Callable<T>> tasks)
       throws InterruptedException, ExecutionException {
     return delegate.invokeAny(wrapTasks(tasks));
   }
 
   @Override
-  public final <T> T invokeAny(Collection<? extends Callable<T>> tasks, long timeout, TimeUnit unit)
+  public final <T extends @Nullable Object> T invokeAny(
+      Collection<? extends Callable<T>> tasks, long timeout, TimeUnit unit)
       throws InterruptedException, ExecutionException, TimeoutException {
     return delegate.invokeAny(wrapTasks(tasks), timeout, unit);
   }
diff --git a/guava/src/com/google/common/util/concurrent/WrappingScheduledExecutorService.java b/guava/src/com/google/common/util/concurrent/WrappingScheduledExecutorService.java
index 4ab700fde574..48f23c12c7cb 100644
--- a/guava/src/com/google/common/util/concurrent/WrappingScheduledExecutorService.java
+++ b/guava/src/com/google/common/util/concurrent/WrappingScheduledExecutorService.java
@@ -20,6 +20,7 @@
 import java.util.concurrent.ScheduledExecutorService;
 import java.util.concurrent.ScheduledFuture;
 import java.util.concurrent.TimeUnit;
+import org.checkerframework.checker.nullness.qual.Nullable;
 
 /**
  * An abstract {@code ScheduledExecutorService} that allows subclasses to {@linkplain
@@ -31,6 +32,7 @@
  */
 @CanIgnoreReturnValue // TODO(cpovirk): Consider being more strict.
 @GwtIncompatible
+@ElementTypesAreNonnullByDefault
 abstract class WrappingScheduledExecutorService extends WrappingExecutorService
     implements ScheduledExecutorService {
   final ScheduledExecutorService delegate;
@@ -46,7 +48,8 @@ public final ScheduledFuture<?> schedule(Runnable command, long delay, TimeUnit
   }
 
   @Override
-  public final <V> ScheduledFuture<V> schedule(Callable<V> task, long delay, TimeUnit unit) {
+  public final <V extends @Nullable Object> ScheduledFuture<V> schedule(
+      Callable<V> task, long delay, TimeUnit unit) {
     return delegate.schedule(wrapTask(task), delay, unit);
   }
 
diff --git a/guava/src/com/google/common/xml/ElementTypesAreNonnullByDefault.java b/guava/src/com/google/common/xml/ElementTypesAreNonnullByDefault.java
new file mode 100644
index 000000000000..b4fb4e3fe470
--- /dev/null
+++ b/guava/src/com/google/common/xml/ElementTypesAreNonnullByDefault.java
@@ -0,0 +1,41 @@
+/*
+ * Copyright (C) 2021 The Guava Authors
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package com.google.common.xml;
+
+import static java.lang.annotation.ElementType.FIELD;
+import static java.lang.annotation.ElementType.METHOD;
+import static java.lang.annotation.ElementType.PARAMETER;
+import static java.lang.annotation.ElementType.TYPE;
+import static java.lang.annotation.RetentionPolicy.RUNTIME;
+
+import com.google.common.annotations.GwtCompatible;
+import java.lang.annotation.Retention;
+import java.lang.annotation.Target;
+import javax.annotation.Nonnull;
+import javax.annotation.meta.TypeQualifierDefault;
+
+/**
+ * Marks all "top-level" types as non-null in a way that is recognized by Kotlin. Note that this
+ * unfortunately includes type-variable usages, so we also provide {@link ParametricNullness} to
+ * "undo" it as best we can.
+ */
+@GwtCompatible
+@Retention(RUNTIME)
+@Target(TYPE)
+@TypeQualifierDefault({FIELD, METHOD, PARAMETER})
+@Nonnull
+@interface ElementTypesAreNonnullByDefault {}
diff --git a/guava/src/com/google/common/xml/ParametricNullness.java b/guava/src/com/google/common/xml/ParametricNullness.java
new file mode 100644
index 000000000000..e4e5d12f0e3b
--- /dev/null
+++ b/guava/src/com/google/common/xml/ParametricNullness.java
@@ -0,0 +1,52 @@
+/*
+ * Copyright (C) 2021 The Guava Authors
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package com.google.common.xml;
+
+import static java.lang.annotation.ElementType.FIELD;
+import static java.lang.annotation.ElementType.METHOD;
+import static java.lang.annotation.ElementType.PARAMETER;
+import static java.lang.annotation.RetentionPolicy.RUNTIME;
+
+import com.google.common.annotations.GwtCompatible;
+import java.lang.annotation.Retention;
+import java.lang.annotation.Target;
+
+/**
+ * Marks a "top-level" type-variable usage as the closest we can get to "non-nullable when
+ * non-nullable; nullable when nullable" (like the Android <a
+ * href="https://android.googlesource.com/platform/libcore/+/master/luni/src/main/java/libcore/util/NullFromTypeParam.java">{@code
+ * NullFromTypeParam}</a>).
+ *
+ * <p>Consumers of this annotation include:
+ *
+ * <ul>
+ *   <li>Kotlin, for which it makes the type-variable usage (a) a Kotlin platform type when the type
+ *       argument is non-nullable and (b) nullable when the type argument is nullable. We use this
+ *       to "undo" {@link ElementTypesAreNonnullByDefault}.
+ *   <li><a href="https://developers.google.com/j2objc">J2ObjC</a>
+ *   <li>{@code NullPointerTester}, at least in the Android backport (where the type-use annotations
+ *       {@code NullPointerTester} would need are not available) and in case of <a
+ *       href="https://bugs.openjdk.java.net/browse/JDK-8202469">JDK-8202469</a>
+ * </ul>
+ *
+ */
+@GwtCompatible
+@Retention(RUNTIME)
+@Target({FIELD, METHOD, PARAMETER})
+@javax.annotation.meta.TypeQualifierNickname
+@javax.annotation.Nonnull(when = javax.annotation.meta.When.UNKNOWN)
+@interface ParametricNullness {}
diff --git a/guava/src/com/google/common/xml/XmlEscapers.java b/guava/src/com/google/common/xml/XmlEscapers.java
index a477217740da..33241f3f3299 100644
--- a/guava/src/com/google/common/xml/XmlEscapers.java
+++ b/guava/src/com/google/common/xml/XmlEscapers.java
@@ -14,7 +14,6 @@
 
 package com.google.common.xml;
 
-import com.google.common.annotations.Beta;
 import com.google.common.annotations.GwtCompatible;
 import com.google.common.escape.Escaper;
 import com.google.common.escape.Escapers;
@@ -38,8 +37,8 @@
  * @author David Beaumont
  * @since 15.0
  */
-@Beta
 @GwtCompatible
+@ElementTypesAreNonnullByDefault
 public class XmlEscapers {
   private XmlEscapers() {}
 
diff --git a/guava/src/com/google/thirdparty/publicsuffix/PublicSuffixPatterns.java b/guava/src/com/google/thirdparty/publicsuffix/PublicSuffixPatterns.java
index f091be78a0be..c987065e4647 100644
--- a/guava/src/com/google/thirdparty/publicsuffix/PublicSuffixPatterns.java
+++ b/guava/src/com/google/thirdparty/publicsuffix/PublicSuffixPatterns.java
@@ -30,7 +30,7 @@
  * determining whether a given domain name is an effective top-level domain (public suffix).
  *
  * <p>Because this class is used in GWT, the data members are stored in a space-efficient manner.
- * {@see TrieParser}.
+ * See {@link TrieParser}.
  *
  * @since 16.0
  */
@@ -42,7 +42,7 @@ private PublicSuffixPatterns() {}
   /** If a hostname is contained as a key in this map, it is a public suffix. */
   public static final ImmutableMap<String, PublicSuffixType> EXACT =
       TrieParser.parseTrie(
-          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+          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gro?lim?oc?pooc?ten?vog??n??t!.&a46oa0fz--nx?b&82wrzc--nx?ulc??emag?gro?l&im?ru,?moc!.reliamym,?t&en?opsgolb,?ude?v&di?og?ta0cu--nx??zibe?業商?織組?路網???z!.&ca?gro?lim?oc?vog????x&a!.&cm,eb,gg,s&e,u,?tac,ue,yx,?t??c!.&hta,ofni,vog???e&d&ef?nay??ma!nab??rof?s??ilften?jt?m!.&bog?gro?moc?t&en?opsgolb,?ude??g?ma2ibgy--nx??o&b!x??f?rex??rbgn--nx?s!.vog??x&am&jt?kt??x???y&4punu--nx?7rr03--nx?a&d!i&loh?rfkcalb??ot!.emyfilauqerp,??g?lp?p!ila??rot?ssin?wdaorb??b!.&duolcym,fo?hcetaidem,lim?moc!.topsgolb,?vog??ab?gur??c!.&ca?dtl?gro?lim?m&oc!.&ecrofelacs.j,topsgolb,??t??orp?s&egolke?serp??ten?vog?zib??amrahp?nega??d&dadog?uts??e&kcoh?ltneb?n&dys?om?rotta??snikcm??g!.&eb,gro?moc?oc?ten?ude?vog??olonhcet!.oc,?rene??hpargotohp?id?k!.&gro?moc?ten?ude??s??l!.&clp?d&em?i??gro?hcs?moc?ten?ude?vog??f?imaf!nacirema??l&a?il??ppus??m!.&eman?gro?lim?moc?t&en?opsgolb,?ude?vog?zib??edaca!.laiciffo,?ra??n&a&ffit?pmoc??os??o&j?s??p!.&gro?lim?moc?pooc?ten?ude?vog???r&e&corg?grus?llag?viled??lewej?otcerid?tnuoc?uxul??s!.&gro?lim?moc?ten?ude?vog??pil??t&efas?i&c?ledif?n&ifx?ummoc!.&bdnevar,gon,murofym,???r&ahc?uces??srevinu??laer?r&ap!.oby,?eporp??uaeb??u!.&bug?gro?lim?moc!.topsgolb,?ten?ude??b!tseb???van!dlo??xes??z&a!.&eman?gro?lim?moc?o&fni?rp??pp?t&en?ni??ude?vog?zib???b!.&az,gro?jsg,moc?ten?ude?vog???c!.&4e,inum.duolc.&rsu,tlf,?m&laer,urtnecatem.motsuc,?oc,topsgolb,??d!.&cos?gro?lop?m&oc?t??ossa?t&en?ra??ude?vog???ib!.&duolcsd,e&ht-rof,mos-rof,rom-rof,?izoj,nafamm,p&i&-on,fles,?ohbew,tfym,?retteb-rof,snd&nyd,uolc,?xro,?g??k!.&duolcj,gro?lim?moc?t&en?ropeletzak.saapu,?ude?vog???m!.&ca?gro?lim?oc?ten?ude?v&da?og????n!.&asq-irom--nx?ca?gro?htlaeh?i&r&c?o&am?ām???wi!k???keeg?l&im?oohcs??neg?oc!.topsgolb,?t&en?nemailrap?vog???a!niflla???rawhcs?s!.&ca?gro?oc???t!.&c&a?s??e&m?n??ibom?l&etoh?im??o&c?fni?g??ro?vt???u!.&gro?moc?oc?ten??rwon??yx!.&e&nozlacol,tisgolb,?gnitfarc,otpaz,??zub??λε?υε?авксом?брс!.&гро?до?ка?р&бо?п!у?????г&б?ро??дкм?зақ?итед?килотак?леб?мок?н&йално?ом??рку?сур!.&арамас,бпс,гро,зиб,ичос,ксм,м&ок,ырк,?рим,я,??тйас?фр?юе?յահ?לארשי?םוק?اي&روس?سيلم?ناتيروم??بر&ع?غملا??ة&كبش?ي&دوعسلا?روس??یدوعسلا??ت&ا&راما?لاصتا??را&ب?ڀ?ھب???ر&ئازجلا?ازاب?صم?طق??سنوت?عقوم?قارع?ك&تيب?يلوثاك??موك?ن&ا&تس&كاپ?کاپ??دوس?ر&يا?یا??مع?يلعلا??درالا?ميلا?ي&رحبلا?طسلف???ه&ارمه?يدوعسلا??وكمارا?يبظوبا?ۃیدوعسلا?टेन?त&राभ?ोराभ??नठगंस?मॉक?्मतराभ?ত&রাভ?ৰাভ??ালংাব?ਤਰਾਭ?તરાભ?ତରାଭ?ாயித்நஇ?ைக்ஙலஇ?்ரூப்பக்ஙிச?్తరాభ?ತರಾಭ?ംതരാഭ?ාකංල?มอค?ยทไ!.&จิกรุธ?ต็นเ?ร&ก์คงอ?าหท??ลาบฐัร?าษกึศ???ວາລ?ეგ?なんみ?アトス?トンイポ?ドウラク?ムコ?ル&グーグ?ーセ??ン&ゾマア?ョシッァフ??业企?东广?乐娱?亚基诺?你爱我?信中?务政?动移?博微?卦八?厅餐?司公?品食?善慈?团集?国中?國中?址网?坡加新?城商?尚时?山佛?店&商?网?酒大里嘉??府政?康健?息信?戏游?拉里格香?拿大?教主天?机手?构机!织组??标商?歌谷?浦利飞?港香!.&人個?司公?府政?絡網?織組?育教???湾台?灣&台?臺??物购?界世?益公?看点?科盈訊電?站网?籍書?线在?络网?网文中?聘招?販通?逊马亚?通联?里嘉?锡马淡?門澳?门澳?闻新?電家?국한?넷닷?성삼?컴닷??");
 
   /**
    * If a hostname is not a key in the EXCLUDE map, and if removing its leftmost component results
@@ -50,7 +50,7 @@ private PublicSuffixPatterns() {}
    */
   public static final ImmutableMap<String, PublicSuffixType> UNDER =
       TrieParser.parseTrie(
-          "ac.vedwa,d&b?uolc.&etiso&isnes,tnegam,?iaznab,rehcnar-no,scitats,??e&b.lrusnart,d.ecapsrebu,noz.notirt,t&atse.etupmoc,is.hsmroftalp,??gp?h&c.tenerif:.cvs,,k?trae.sppad:.zzb,,?k&c?f?nil.bewd,rowten.secla,u.hcs??ln.lrusnart,m&j?m?oc.&duolcmeaeboda.ved,edonil.recnalabedon,ico-remotsuc:.&ico,pco,sco,?,mme0,s&t&cejboedonil,nemelepiuq,?wanozama.&1-etupmoc,ble,etupmoc,??t&neyoj.snc,opsppa.r,???n&c.moc.swanozama.&ble,etupmoc,?ur.edoc,?o&c.pato,i.&duolciaznab.sdraykcab,elacsnoom,oir-no,reniatnoceruza,s&3k-no,olots,?xcq.sys,y5s,??p&j.&a&mahokoy?yogan??ebok?i&adnes?kasawak??oroppas?uhsuykatik??n?pa.knalfhtron,?r&b.mon?e??s&edoc.owo,w.rosivda,?t&a.&ofnistro.&nednuk,xe,?smcerutuf:.&ni,xe,?,?en.&cimonotpyrc,hvo.&gnitsoh,saapbew,???u&e.lrusnart,r.onijym.&gni&dnal,tsoh,?murtceps,spv,??ved.&erahbew,gts,lcl,yawetag,?z&c.murtnecatem.duolc,yx.tibelet,??");
+          "ac.vedwa,d&b?i.ym.ssr,uolc.&etiso&isnes,tnegam,?iaznab,rehcnar-no,scitats,??e&b.lrusnart,d.&ecapsrebu,yksurf,?noz.notirt,t&atse.etupmoc,is.&areduolc,hsmroftalp,tst,???g&oog.tnetnocresu,p??h&c.tenerif:.cvs,,k?trae.sppad:.zzb,,?k&c?f?nil.bewd,rowten.secla,u.hcs??ln.lrusnart,m&j?m?oc.&duolcmeaeboda.ved,edonil.recnalabedon,ico-remotsuc:.&ico,pco,sco,?,lrihwyap,mme0,osseccandcved,s&ecapsnaecolatigid,t&cejbo&edonil,rtluv,?nemelepiuq,?wanozama.&1-etupmoc,ble,etupmoc,??t&neyoj.snc,opsppa.r,???n&c.moc.swanozama.&ble,etupmoc,?ur.edoc,?o&c.pato,i.&duolciaznab.sdraykcab,elacsnoom,oir-no,reniatnoceruza,s&3k-no,olots,?xcq.sys,y5s,??p&j.&a&mahokoy?yogan??ebok?i&adnes?kasawak??oroppas?uhsuykatik??n?pa.&knalfhtron,repoleved,tegeb,??r&b.mon?e??s&edoc.owo,noitulos.rehid,w.rosivda,?t&a.&ofnistro.&nednuk,xe,?smcerutuf:.&ni,xe,?,?en.&cimonotpyrc,hvo.&gnitsoh,saapbew,???u&e.lrusnart,r.onijym.&gni&dnal,tsoh,?murtceps,spv,??ved.&e&gats&gts,lcl,?rahbew,?gts,lcl,yawetag,?z&c.murtnecatem.duolc,yx.tibelet,??");
 
   /**
    * The elements in this map would pass the UNDER test, but are known not to be public suffixes and
diff --git a/guava/src/com/google/thirdparty/publicsuffix/TrieParser.java b/guava/src/com/google/thirdparty/publicsuffix/TrieParser.java
index dd7778040ef2..89cdadd3da04 100644
--- a/guava/src/com/google/thirdparty/publicsuffix/TrieParser.java
+++ b/guava/src/com/google/thirdparty/publicsuffix/TrieParser.java
@@ -36,7 +36,7 @@ static ImmutableMap<String, PublicSuffixType> parseTrie(CharSequence encoded) {
     while (idx < encodedLen) {
       idx += doParseTrieToBuilder(Queues.<CharSequence>newArrayDeque(), encoded, idx, builder);
     }
-    return builder.build();
+    return builder.buildOrThrow();
   }
 
   /**
diff --git a/pom.xml b/pom.xml
index 13c549ef092d..ab81fb618d0e 100644
--- a/pom.xml
+++ b/pom.xml
@@ -6,7 +6,7 @@
   <modelVersion>4.0.0</modelVersion>
   <groupId>com.google.guava</groupId>
   <artifactId>guava-parent</artifactId>
-  <version>30.1.1-jre</version>
+  <version>31.1-jre</version>
   <packaging>pom</packaging>
   <name>Guava Maven Parent</name>
   <description>Parent for guava artifacts</description>
@@ -14,27 +14,15 @@
   <properties>
     <!-- Override this with -Dtest.include="**/SomeTest.java" on the CLI -->
     <test.include>%regex[.*.class]</test.include>
-    <truth.version>1.1</truth.version>
-    <!--
-      Upgrading to 1.19 breaks things: Animal Sniffer reports a problem with the
-      use of ClassValue in FuturesGetChecked, even though we've added a
-      suppression annotation.
-
-      The problem might be
-      https://github.com/mojohaus/animal-sniffer/issues/131.
-
-      We could probably work around this with a different suppression strategy,
-      perhaps (untested):
-
-      <ignores><ignore>com.google.common.util.concurrent.FuturesGetChecked$GetCheckedTypeValidatorHolder$ClassValueValidator</ignore></ignores>
-
-      But upgrading doesn't really buy us much, as far as I know. (1.19 does
-      check test code in addition to prod code, but I don't think we care.)
-    -->
-    <animal.sniffer.version>1.18</animal.sniffer.version>
+    <truth.version>1.1.2</truth.version>
+    <checker-framework.version>3.32.0</checker-framework.version>
+    <animal.sniffer.version>1.20</animal.sniffer.version>
     <maven-javadoc-plugin.version>3.1.0</maven-javadoc-plugin.version>
+    <!-- Empty for all JDKs but 9-12 -->
+    <maven-javadoc-plugin.additionalJOptions></maven-javadoc-plugin.additionalJOptions>
     <maven-source-plugin.version>3.2.1</maven-source-plugin.version>
     <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
+    <test.add.opens></test.add.opens>
   </properties>
   <issueManagement>
     <system>GitHub Issues</system>
@@ -68,13 +56,15 @@
     </developer>
   </developers>
   <ciManagement>
-    <system>Travis CI</system>
-    <url>https://travis-ci.org/google/guava</url>
+    <system>GitHub Actions</system>
+    <url>https://github.com/google/guava/actions</url>
   </ciManagement>
   <modules>
     <module>guava</module>
     <module>guava-bom</module>
+<!-- Disable Google Web Toolkit - we don't need and has build problems.
     <module>guava-gwt</module>
+ -->
     <module>guava-testlib</module>
     <module>guava-tests</module>
   </modules>
@@ -167,7 +157,7 @@
           <artifactId>animal-sniffer-maven-plugin</artifactId>
           <version>${animal.sniffer.version}</version>
           <configuration>
-            <annotations>com.google.common.util.concurrent.IgnoreJRERequirement</annotations>
+            <checkTestClasses>true</checkTestClasses>
             <signature>
               <groupId>org.codehaus.mojo.signature</groupId>
               <artifactId>java18</artifactId>
@@ -199,6 +189,7 @@
             </additionalOptions>
             <linksource>true</linksource>
             <source>8</source>
+            <additionalJOption>${maven-javadoc-plugin.additionalJOptions}</additionalJOption>
           </configuration>
           <executions>
             <execution>
@@ -236,7 +227,7 @@
             <runOrder>alphabetical</runOrder>
             <!-- Set max heap for tests. -->
             <!-- Catch dependencies on the default locale by setting it to hi-IN. -->
-            <argLine>-Xmx4g -Duser.language=hi -Duser.country=IN</argLine>
+            <argLine>-Xmx1536M -Duser.language=hi -Duser.country=IN ${test.add.opens}</argLine>
           </configuration>
         </plugin>
         <plugin>
@@ -274,12 +265,23 @@
       <dependency>
         <groupId>org.checkerframework</groupId>
         <artifactId>checker-qual</artifactId>
-        <version>3.30.0</version>
+        <version>${checker-framework.version}</version>
+      </dependency>
+      <dependency>
+        <groupId>org.checkerframework</groupId>
+        <artifactId>checker-util</artifactId>
+        <version>${checker-framework.version}</version>
+      </dependency>
+      <dependency>
+        <groupId>org.checkerframework</groupId>
+        <artifactId>checker-qual</artifactId>
+        <version>${checker-framework.version}</version>
+        <classifier>sources</classifier>
       </dependency>
       <dependency>
         <groupId>com.google.errorprone</groupId>
         <artifactId>error_prone_annotations</artifactId>
-        <version>2.5.1</version>
+        <version>2.11.0</version>
       </dependency>
       <dependency>
         <groupId>com.google.j2objc</groupId>
@@ -295,19 +297,19 @@
       <dependency>
         <groupId>org.easymock</groupId>
         <artifactId>easymock</artifactId>
-        <version>4.2</version>
+        <version>4.3</version>
         <scope>test</scope>
       </dependency>
       <dependency>
         <groupId>org.mockito</groupId>
         <artifactId>mockito-core</artifactId>
-        <version>3.6.28</version>
+        <version>3.9.0</version>
         <scope>test</scope>
       </dependency>
       <dependency>
         <groupId>com.google.jimfs</groupId>
         <artifactId>jimfs</artifactId>
-        <version>1.1</version>
+        <version>1.2</version>
         <scope>test</scope>
       </dependency>
       <dependency>
@@ -399,5 +401,45 @@
           </plugins>
       </build>
     </profile>
+    <profile>
+      <!--
+          Passes JDK 11-12-specific `no-module-directories` flag to Javadoc tool,
+          which is required to make symbol search work correctly in the generated
+          pages.
+
+          This flag does not exist on 9-10 and 13+ (https://bugs.openjdk.java.net/browse/JDK-8215582).
+
+          Consider removing it once our release and test scripts are migrated to a recent JDK (17+).
+       -->
+      <id>javadocs-jdk11-12</id>
+      <activation>
+        <jdk>[11,13)</jdk>
+      </activation>
+      <properties>
+        <maven-javadoc-plugin.additionalJOptions>--no-module-directories</maven-javadoc-plugin.additionalJOptions>
+      </properties>
+    </profile>
+    <profile>
+      <id>open-jre-modules</id>
+      <activation>
+        <jdk>[9,]</jdk>
+      </activation>
+      <properties>
+        <!--
+            Some tests need reflective access to the internals of these packages. It is only the
+            tests themselves and not the code being tested that needs that access, though there's no
+            obvious way to ensure that.
+
+            We could consider arranging things so that only the tests we know need this would get
+            the add-opens. Right now that doesn't seem worth the effort, though.
+        -->
+        <test.add.opens>
+          --add-opens java.base/java.lang=ALL-UNNAMED
+          --add-opens java.base/java.util=ALL-UNNAMED
+          --add-opens java.base/java.util.concurrent.locks=ALL-UNNAMED
+          --add-opens java.base/sun.security.jca=ALL-UNNAMED
+        </test.add.opens>
+      </properties>
+    </profile>
   </profiles>
 </project>

From bafbf636c5cbe7f4eac55973dd7c4e5fc38d9b21 Mon Sep 17 00:00:00 2001
From: Mark Roberts <markro@cs.washington.edu>
Date: Wed, 12 Apr 2023 11:57:58 -0700
Subject: [PATCH 07/21] fix typo

---
 guava/src/com/google/common/base/Preconditions.java | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/guava/src/com/google/common/base/Preconditions.java b/guava/src/com/google/common/base/Preconditions.java
index 5ffc756bf58a..9f9e6e176ca4 100644
--- a/guava/src/com/google/common/base/Preconditions.java
+++ b/guava/src/com/google/common/base/Preconditions.java
@@ -553,7 +553,7 @@ public static void checkState(
       boolean expression,
       /*
        * TODO(cpovirk): Consider removing @CheckForNull here, as we've done with the other methods'
-       * errorMessageTemplate parameters: It it unlikely that callers intend for their string
+       * errorMessageTemplate parameters: It is unlikely that callers intend for their string
        * template to be null (though we do handle that case gracefully at runtime). I've left this
        * one as it is because one of our users has defined a wrapper API around Preconditions,
        * declaring a checkState method that accepts a possibly null template. So we'd need to update

From 852c05c6cc60a82913f26b3ac8307ef5b66926c3 Mon Sep 17 00:00:00 2001
From: Mark Roberts <markro@cs.washington.edu>
Date: Wed, 12 Apr 2023 16:19:16 -0700
Subject: [PATCH 08/21] add signedness annotations

---
 .../com/google/common/cache/LocalCache.java   | 12 ++++++----
 .../src/com/google/common/io/ByteStreams.java |  9 ++++----
 .../common/io/CountingOutputStream.java       |  7 ++++--
 .../io/LittleEndianDataInputStream.java       |  2 ++
 .../google/common/primitives/Booleans.java    | 14 +++++++----
 .../com/google/common/primitives/Bytes.java   | 23 +++++++++++--------
 .../com/google/common/primitives/Chars.java   | 16 +++++++++----
 .../com/google/common/primitives/Doubles.java | 14 ++++++-----
 .../com/google/common/primitives/Floats.java  | 14 ++++++-----
 .../primitives/ImmutableDoubleArray.java      | 12 ++++++----
 .../common/primitives/ImmutableIntArray.java  | 23 ++++++++++++-------
 .../common/primitives/ImmutableLongArray.java | 18 ++++++++++-----
 .../com/google/common/primitives/Ints.java    | 21 +++++++++++------
 .../com/google/common/primitives/Longs.java   | 20 ++++++++++------
 .../common/primitives/ParseRequest.java       |  2 ++
 .../com/google/common/primitives/Shorts.java  | 23 +++++++++++--------
 .../common/primitives/UnsignedBytes.java      | 11 +++++++++
 .../common/primitives/UnsignedInteger.java    |  7 ++++++
 .../common/primitives/UnsignedInts.java       | 12 +++++++++-
 .../common/primitives/UnsignedLong.java       |  2 ++
 .../common/primitives/UnsignedLongs.java      |  8 ++++---
 21 files changed, 184 insertions(+), 86 deletions(-)

diff --git a/guava/src/com/google/common/cache/LocalCache.java b/guava/src/com/google/common/cache/LocalCache.java
index 56e32c8f97d6..56353772fc89 100644
--- a/guava/src/com/google/common/cache/LocalCache.java
+++ b/guava/src/com/google/common/cache/LocalCache.java
@@ -86,6 +86,9 @@
 import java.util.logging.Level;
 import java.util.logging.Logger;
 import org.checkerframework.checker.nullness.qual.Nullable;
+import org.checkerframework.checker.signedness.qual.PolySigned;
+import org.checkerframework.checker.signedness.qual.Signed;
+import org.checkerframework.framework.qual.AnnotatedFor;
 
 /**
  * The concurrent hash map implementation built by {@link CacheBuilder}.
@@ -97,6 +100,7 @@
  * @author Bob Lee ({@code com.google.common.collect.MapMaker})
  * @author Doug Lea ({@code ConcurrentHashMap})
  */
+@AnnotatedFor({"signedness"})
 @SuppressWarnings({
   "GoodTime", // lots of violations (nanosecond math)
   "nullness", // too much trouble for the payoff
@@ -4528,8 +4532,8 @@ public void clear() {
     // https://code.google.com/p/android/issues/detail?id=36519 / http://r.android.com/47508
 
     @Override
-    public Object[] toArray() {
-      return toArrayList(this).toArray();
+    public @PolySigned Object[] toArray(LocalCache<K,V>.AbstractCacheSet<T> this) {
+      return (@PolySigned Object[]) toArrayList(this).toArray();
     }
 
     @Override
@@ -4616,8 +4620,8 @@ public boolean contains(Object o) {
     // https://code.google.com/p/android/issues/detail?id=36519 / http://r.android.com/47508
 
     @Override
-    public Object[] toArray() {
-      return toArrayList(this).toArray();
+    public @PolySigned Object[] toArray(LocalCache<K,V>.Values this) {
+      return (@PolySigned Object[]) toArrayList(this).toArray();
     }
 
     @Override
diff --git a/guava/src/com/google/common/io/ByteStreams.java b/guava/src/com/google/common/io/ByteStreams.java
index 16e1dcc14ed5..cb388e82e1b1 100644
--- a/guava/src/com/google/common/io/ByteStreams.java
+++ b/guava/src/com/google/common/io/ByteStreams.java
@@ -43,17 +43,17 @@
 import java.util.ArrayDeque;
 import java.util.Arrays;
 import java.util.Deque;
+import java.util.Queue;
+import javax.annotation.CheckForNull;
 import org.checkerframework.checker.index.qual.GTENegativeOne;
 import org.checkerframework.checker.index.qual.IndexOrHigh;
 import org.checkerframework.checker.index.qual.LTEqLengthOf;
 import org.checkerframework.checker.index.qual.LTLengthOf;
 import org.checkerframework.checker.index.qual.LessThan;
 import org.checkerframework.checker.index.qual.NonNegative;
-import org.checkerframework.checker.signedness.qual.PolySigned;
-import java.util.Deque;
-import java.util.Queue;
-import javax.annotation.CheckForNull;
 import org.checkerframework.checker.nullness.qual.Nullable;
+import org.checkerframework.checker.signedness.qual.PolySigned;
+import org.checkerframework.framework.qual.AnnotatedFor;
 
 /**
  * Provides utility methods for working with byte arrays and I/O streams.
@@ -62,6 +62,7 @@
  * @author Colin Decker
  * @since 1.0
  */
+@AnnotatedFor({"signedness"})
 @GwtIncompatible
 @ElementTypesAreNonnullByDefault
 public final class ByteStreams {
diff --git a/guava/src/com/google/common/io/CountingOutputStream.java b/guava/src/com/google/common/io/CountingOutputStream.java
index b2ca17c5f7a8..f74effab0f00 100644
--- a/guava/src/com/google/common/io/CountingOutputStream.java
+++ b/guava/src/com/google/common/io/CountingOutputStream.java
@@ -23,6 +23,8 @@
 import org.checkerframework.checker.index.qual.IndexOrHigh;
 import org.checkerframework.checker.index.qual.LTLengthOf;
 import org.checkerframework.checker.index.qual.NonNegative;
+import org.checkerframework.checker.signedness.qual.PolySigned;
+import org.checkerframework.framework.qual.AnnotatedFor;
 
 /**
  * An OutputStream that counts the number of bytes written.
@@ -30,6 +32,7 @@
  * @author Chris Nokleberg
  * @since 1.0
  */
+@AnnotatedFor({"signedness"})
 @GwtIncompatible
 @ElementTypesAreNonnullByDefault
 public final class CountingOutputStream extends FilterOutputStream {
@@ -51,13 +54,13 @@ public long getCount() {
   }
 
   @Override
-  public void write(byte[] b, @IndexOrHigh("#1") int off, @NonNegative @LTLengthOf(value = "#1", offset = "#2 - 1") int len) throws IOException {
+  public void write(@PolySigned byte[] b, @IndexOrHigh("#1") int off, @NonNegative @LTLengthOf(value = "#1", offset = "#2 - 1") int len) throws IOException {
     out.write(b, off, len);
     count += len;
   }
 
   @Override
-  public void write(int b) throws IOException {
+  public void write(@PolySigned int b) throws IOException {
     out.write(b);
     count++;
   }
diff --git a/guava/src/com/google/common/io/LittleEndianDataInputStream.java b/guava/src/com/google/common/io/LittleEndianDataInputStream.java
index 361b409c1e21..a48c81c3cf9e 100644
--- a/guava/src/com/google/common/io/LittleEndianDataInputStream.java
+++ b/guava/src/com/google/common/io/LittleEndianDataInputStream.java
@@ -30,6 +30,7 @@
 import org.checkerframework.checker.index.qual.IndexOrHigh;
 import org.checkerframework.checker.index.qual.LTLengthOf;
 import org.checkerframework.checker.index.qual.NonNegative;
+import org.checkerframework.framework.qual.AnnotatedFor;
 
 /**
  * An implementation of {@link DataInput} that uses little-endian byte ordering for reading {@code
@@ -42,6 +43,7 @@
  * @author Keith Bottner
  * @since 8.0
  */
+@AnnotatedFor({"signedness"})
 @Beta
 @GwtIncompatible
 @ElementTypesAreNonnullByDefault
diff --git a/guava/src/com/google/common/primitives/Booleans.java b/guava/src/com/google/common/primitives/Booleans.java
index 46b21c240b69..c59285877a3f 100644
--- a/guava/src/com/google/common/primitives/Booleans.java
+++ b/guava/src/com/google/common/primitives/Booleans.java
@@ -41,8 +41,10 @@
 import org.checkerframework.checker.index.qual.HasSubsequence;
 import org.checkerframework.checker.index.qual.LessThan;
 import org.checkerframework.checker.nullness.qual.Nullable;
+import org.checkerframework.checker.signedness.qual.Signed;
 import org.checkerframework.checker.signedness.qual.UnknownSignedness;
 import org.checkerframework.common.value.qual.MinLen;
+import org.checkerframework.framework.qual.AnnotatedFor;
 
 /**
  * Static utility methods pertaining to {@code boolean} primitives, that are not already found in
@@ -54,6 +56,7 @@
  * @author Kevin Bourrillion
  * @since 1.0
  */
+@AnnotatedFor({"signedness"})
 @GwtCompatible
 @ElementTypesAreNonnullByDefault
 public final class Booleans {
@@ -433,18 +436,19 @@ public Boolean get(@IndexFor("this") int index) {
     }
 
     @Override
+    @SuppressWarnings("signedness:cast.unsafe")
     public boolean contains(@CheckForNull @UnknownSignedness Object target) {
       // Overridden to prevent a ton of boxing
       return (target instanceof Boolean)
-          && Booleans.indexOf(array, (Boolean) target, start, end) != -1;
+          && Booleans.indexOf(array, (@Signed Boolean) target, start, end) != -1;
     }
 
     @Override
-    @SuppressWarnings("lowerbound:return")
+    @SuppressWarnings("signedness:cast.unsafe")
     public @IndexOrLow("this") int indexOf(@CheckForNull @UnknownSignedness Object target) {
       // Overridden to prevent a ton of boxing
       if (target instanceof Boolean) {
-        int i = Booleans.indexOf(array, (Boolean) target, start, end);
+        int i = Booleans.indexOf(array, (@Signed Boolean) target, start, end);
         if (i >= 0) {
           return i - start;
         }
@@ -453,11 +457,11 @@ public boolean contains(@CheckForNull @UnknownSignedness Object target) {
     }
 
     @Override
-    @SuppressWarnings("lowerbound:return")
+    @SuppressWarnings("signedness:cast.unsafe")
     public @IndexOrLow("this") int lastIndexOf(@CheckForNull @UnknownSignedness Object target) {
       // Overridden to prevent a ton of boxing
       if (target instanceof Boolean) {
-        int i = Booleans.lastIndexOf(array, (Boolean) target, start, end);
+        int i = Booleans.lastIndexOf(array, (@Signed Boolean) target, start, end);
         if (i >= 0) {
           return i - start;
         }
diff --git a/guava/src/com/google/common/primitives/Bytes.java b/guava/src/com/google/common/primitives/Bytes.java
index d8df5407f606..0abcee6587ed 100644
--- a/guava/src/com/google/common/primitives/Bytes.java
+++ b/guava/src/com/google/common/primitives/Bytes.java
@@ -39,7 +39,10 @@
 import org.checkerframework.checker.index.qual.HasSubsequence;
 import org.checkerframework.checker.index.qual.LessThan;
 import org.checkerframework.checker.nullness.qual.Nullable;
+import org.checkerframework.checker.signedness.qual.Signed;
+import org.checkerframework.checker.signedness.qual.UnknownSignedness;
 import org.checkerframework.common.value.qual.MinLen;
+import org.checkerframework.framework.qual.AnnotatedFor;
 
 /**
  * Static utility methods pertaining to {@code byte} primitives, that are not already found in
@@ -55,6 +58,7 @@
  */
 // TODO(kevinb): how to prevent warning on UnsignedBytes when building GWT
 // javadoc?
+@AnnotatedFor({"signedness"})
 @GwtCompatible
 @ElementTypesAreNonnullByDefault
 public final class Bytes {
@@ -294,17 +298,18 @@ public Byte get(@IndexFor("this") int index) {
     }
 
     @Override
-    public boolean contains(@CheckForNull Object target) {
+    @SuppressWarnings("signedness:cast.unsafe")
+    public boolean contains(@CheckForNull @UnknownSignedness Object target) {
       // Overridden to prevent a ton of boxing
-      return (target instanceof Byte) && Bytes.indexOf(array, (Byte) target, start, end) != -1;
+      return (target instanceof Byte) && Bytes.indexOf(array, (@Signed Byte) target, start, end) != -1;
     }
 
     @Override
-    @SuppressWarnings("index:return")
-    public @IndexOrLow("this") int indexOf(@CheckForNull Object target) {
+    @SuppressWarnings("signedness:cast.unsafe")
+    public @IndexOrLow("this") int indexOf(@CheckForNull @UnknownSignedness Object target) {
       // Overridden to prevent a ton of boxing
       if (target instanceof Byte) {
-        int i = Bytes.indexOf(array, (Byte) target, start, end);
+        int i = Bytes.indexOf(array, (@Signed Byte) target, start, end);
         if (i >= 0) {
           return i - start;
         }
@@ -313,11 +318,11 @@ public boolean contains(@CheckForNull Object target) {
     }
 
     @Override
-    @SuppressWarnings("index:return")
-    public @IndexOrLow("this") int lastIndexOf(@CheckForNull Object target) {
+    @SuppressWarnings("signedness:cast.unsafe")
+    public @IndexOrLow("this") int lastIndexOf(@CheckForNull @UnknownSignedness Object target) {
       // Overridden to prevent a ton of boxing
       if (target instanceof Byte) {
-        int i = Bytes.lastIndexOf(array, (Byte) target, start, end);
+        int i = Bytes.lastIndexOf(array, (@Signed Byte) target, start, end);
         if (i >= 0) {
           return i - start;
         }
@@ -346,7 +351,7 @@ public List<Byte> subList(@IndexOrHigh("this") int fromIndex, @IndexOrHigh("this
     }
 
     @Override
-    public boolean equals(@CheckForNull Object object) {
+    public boolean equals(@CheckForNull @UnknownSignedness Object object) {
       if (object == this) {
         return true;
       }
diff --git a/guava/src/com/google/common/primitives/Chars.java b/guava/src/com/google/common/primitives/Chars.java
index 42af35791d77..28462e915977 100644
--- a/guava/src/com/google/common/primitives/Chars.java
+++ b/guava/src/com/google/common/primitives/Chars.java
@@ -42,8 +42,11 @@
 import org.checkerframework.checker.index.qual.HasSubsequence;
 import org.checkerframework.checker.index.qual.LessThan;
 import org.checkerframework.checker.nullness.qual.Nullable;
+import org.checkerframework.checker.signedness.qual.Signed;
+import org.checkerframework.checker.signedness.qual.UnknownSignedness;
 import org.checkerframework.common.value.qual.IntRange;
 import org.checkerframework.common.value.qual.MinLen;
+import org.checkerframework.framework.qual.AnnotatedFor;
 
 /**
  * Static utility methods pertaining to {@code char} primitives, that are not already found in
@@ -58,6 +61,7 @@
  * @author Kevin Bourrillion
  * @since 1.0
  */
+@AnnotatedFor({"signedness"})
 @GwtCompatible(emulated = true)
 @ElementTypesAreNonnullByDefault
 public final class Chars {
@@ -315,6 +319,7 @@ public static char[] concat(char[]... arrays) {
    * use a shared {@link java.nio.ByteBuffer} instance, or use {@link
    * com.google.common.io.ByteStreams#newDataOutput()} to get a growable buffer.
    */
+  @SuppressWarnings("signedness:return")
   @GwtIncompatible // doesn't work
   public static byte[] toByteArray(char value) {
     return new byte[] {(byte) (value >> 8), (byte) value};
@@ -342,7 +347,7 @@ public static char fromByteArray(byte @MinLen(Chars.BYTES)[] bytes) {
    *
    * @since 7.0
    */
-  @SuppressWarnings("index") // https://github.com/typetools/checker-framework/issues/2540
+  @SuppressWarnings("signedness:cast.unsafe")
   @GwtIncompatible // doesn't work
   public static char fromBytes(byte b1, byte b2) {
     return (char) ((b1 << 8) | (b2 & 0xFF));
@@ -447,6 +452,7 @@ public static char[] toArray(Collection<Character> collection) {
       return ((CharArrayAsList) collection).toCharArray();
     }
 
+    @SuppressWarnings("signedness:assignment")
     Object[] boxedArray = collection.toArray();
     int len = boxedArray.length;
     char[] array = new char[len];
@@ -567,7 +573,7 @@ public Character get(@IndexFor("this") int index) {
     }
 
     @Override
-    public boolean contains(@CheckForNull Object target) {
+    public boolean contains(@CheckForNull @UnknownSignedness Object target) {
       // Overridden to prevent a ton of boxing
       return (target instanceof Character)
           && Chars.indexOf(array, (Character) target, start, end) != -1;
@@ -575,7 +581,7 @@ public boolean contains(@CheckForNull Object target) {
 
     @Override
     @SuppressWarnings("lowerbound:return")
-    public @IndexOrLow("this") int indexOf(@CheckForNull Object target) {
+    public @IndexOrLow("this") int indexOf(@CheckForNull @UnknownSignedness Object target) {
       // Overridden to prevent a ton of boxing
       if (target instanceof Character) {
         int i = Chars.indexOf(array, (Character) target, start, end);
@@ -588,7 +594,7 @@ public boolean contains(@CheckForNull Object target) {
 
     @Override
     @SuppressWarnings("lowerbound:return")
-    public @IndexOrLow("this") int lastIndexOf(@CheckForNull Object target) {
+    public @IndexOrLow("this") int lastIndexOf(@CheckForNull @UnknownSignedness Object target) {
       // Overridden to prevent a ton of boxing
       if (target instanceof Character) {
         int i = Chars.lastIndexOf(array, (Character) target, start, end);
@@ -620,7 +626,7 @@ public List<Character> subList(@IndexOrHigh("this") int fromIndex, @IndexOrHigh(
     }
 
     @Override
-    public boolean equals(@CheckForNull Object object) {
+    public boolean equals(@CheckForNull @UnknownSignedness Object object) {
       if (object == this) {
         return true;
       }
diff --git a/guava/src/com/google/common/primitives/Doubles.java b/guava/src/com/google/common/primitives/Doubles.java
index 25002829d719..c4d7c5581a4d 100644
--- a/guava/src/com/google/common/primitives/Doubles.java
+++ b/guava/src/com/google/common/primitives/Doubles.java
@@ -48,7 +48,10 @@
 import org.checkerframework.checker.index.qual.HasSubsequence;
 import org.checkerframework.checker.index.qual.LessThan;
 import org.checkerframework.checker.nullness.qual.Nullable;
+import org.checkerframework.checker.signedness.qual.Signed;
+import org.checkerframework.checker.signedness.qual.UnknownSignedness;
 import org.checkerframework.common.value.qual.MinLen;
+import org.checkerframework.framework.qual.AnnotatedFor;
 
 /**
  * Static utility methods pertaining to {@code double} primitives, that are not already found in
@@ -60,6 +63,7 @@
  * @author Kevin Bourrillion
  * @since 1.0
  */
+@AnnotatedFor({"signedness"})
 @GwtCompatible(emulated = true)
 @ElementTypesAreNonnullByDefault
 public final class Doubles extends DoublesMethodsForWeb {
@@ -584,15 +588,14 @@ public Spliterator.OfDouble spliterator() {
     }
 
     @Override
-    public boolean contains(@CheckForNull Object target) {
+    public boolean contains(@CheckForNull @UnknownSignedness Object target) {
       // Overridden to prevent a ton of boxing
       return (target instanceof Double)
           && Doubles.indexOf(array, (Double) target, start, end) != -1;
     }
 
     @Override
-    @SuppressWarnings("lowerbound:return")
-    public @IndexOrLow("this") int indexOf(@CheckForNull Object target) {
+    public @IndexOrLow("this") int indexOf(@CheckForNull @UnknownSignedness Object target) {
       // Overridden to prevent a ton of boxing
       if (target instanceof Double) {
         int i = Doubles.indexOf(array, (Double) target, start, end);
@@ -604,8 +607,7 @@ public boolean contains(@CheckForNull Object target) {
     }
 
     @Override
-    @SuppressWarnings("lowerbound:return")
-    public @IndexOrLow("this")int lastIndexOf(@CheckForNull Object target) {
+    public @IndexOrLow("this")int lastIndexOf(@CheckForNull @UnknownSignedness Object target) {
       // Overridden to prevent a ton of boxing
       if (target instanceof Double) {
         int i = Doubles.lastIndexOf(array, (Double) target, start, end);
@@ -637,7 +639,7 @@ public List<Double> subList(@IndexOrHigh("this") int fromIndex, @IndexOrHigh("th
     }
 
     @Override
-    public boolean equals(@CheckForNull Object object) {
+    public boolean equals(@CheckForNull @UnknownSignedness Object object) {
       if (object == this) {
         return true;
       }
diff --git a/guava/src/com/google/common/primitives/Floats.java b/guava/src/com/google/common/primitives/Floats.java
index 629892fbfa4e..2bcd0a84b963 100644
--- a/guava/src/com/google/common/primitives/Floats.java
+++ b/guava/src/com/google/common/primitives/Floats.java
@@ -46,7 +46,10 @@
 import org.checkerframework.checker.index.qual.HasSubsequence;
 import org.checkerframework.checker.index.qual.LessThan;
 import org.checkerframework.checker.nullness.qual.Nullable;
+import org.checkerframework.checker.signedness.qual.Signed;
+import org.checkerframework.checker.signedness.qual.UnknownSignedness;
 import org.checkerframework.common.value.qual.MinLen;
+import org.checkerframework.framework.qual.AnnotatedFor;
 
 /**
  * Static utility methods pertaining to {@code float} primitives, that are not already found in
@@ -58,6 +61,7 @@
  * @author Kevin Bourrillion
  * @since 1.0
  */
+@AnnotatedFor({"signedness"})
 @GwtCompatible(emulated = true)
 @ElementTypesAreNonnullByDefault
 public final class Floats extends FloatsMethodsForWeb {
@@ -571,14 +575,13 @@ public Float get(@IndexFor("this") int index) {
     }
 
     @Override
-    public boolean contains(@CheckForNull Object target) {
+    public boolean contains(@CheckForNull @UnknownSignedness Object target) {
       // Overridden to prevent a ton of boxing
       return (target instanceof Float) && Floats.indexOf(array, (Float) target, start, end) != -1;
     }
 
     @Override
-    @SuppressWarnings("lowerbound:return")
-    public @IndexOrLow("this") int indexOf(@CheckForNull Object target) {
+    public @IndexOrLow("this") int indexOf(@CheckForNull @UnknownSignedness Object target) {
       // Overridden to prevent a ton of boxing
       if (target instanceof Float) {
         int i = Floats.indexOf(array, (Float) target, start, end);
@@ -590,8 +593,7 @@ public boolean contains(@CheckForNull Object target) {
     }
 
     @Override
-    @SuppressWarnings("lowerbound:return")
-    public @IndexOrLow("this") int lastIndexOf(@CheckForNull Object target) {
+    public @IndexOrLow("this") int lastIndexOf(@CheckForNull @UnknownSignedness Object target) {
       // Overridden to prevent a ton of boxing
       if (target instanceof Float) {
         int i = Floats.lastIndexOf(array, (Float) target, start, end);
@@ -623,7 +625,7 @@ public List<Float> subList(@IndexOrHigh("this") int fromIndex, @IndexOrHigh("thi
     }
 
     @Override
-    public boolean equals(@CheckForNull Object object) {
+    public boolean equals(@CheckForNull @UnknownSignedness Object object) {
       if (object == this) {
         return true;
       }
diff --git a/guava/src/com/google/common/primitives/ImmutableDoubleArray.java b/guava/src/com/google/common/primitives/ImmutableDoubleArray.java
index 665bc539d18c..62437e86230a 100644
--- a/guava/src/com/google/common/primitives/ImmutableDoubleArray.java
+++ b/guava/src/com/google/common/primitives/ImmutableDoubleArray.java
@@ -46,7 +46,10 @@
 import org.checkerframework.checker.index.qual.HasSubsequence;
 import org.checkerframework.checker.index.qual.LessThan;
 import org.checkerframework.checker.nullness.qual.Nullable;
+import org.checkerframework.checker.signedness.qual.Signed;
+import org.checkerframework.checker.signedness.qual.UnknownSignedness;
 import org.checkerframework.dataflow.qual.Pure;
+import org.checkerframework.framework.qual.AnnotatedFor;
 
 /**
  * An immutable array of {@code double} values, with an API resembling {@link List}.
@@ -98,6 +101,7 @@
  *
  * @since 22.0
  */
+@AnnotatedFor({"signedness"})
 @Beta
 @GwtCompatible
 @Immutable
@@ -543,17 +547,17 @@ public Double get(@IndexFor("this") int index) {
     }
 
     @Override
-    public boolean contains(@CheckForNull Object target) {
+    public boolean contains(@CheckForNull @UnknownSignedness Object target) {
       return indexOf(target) >= 0;
     }
 
     @Override
-    public @GTENegativeOne int indexOf(@CheckForNull Object target) {
+    public @GTENegativeOne int indexOf(@CheckForNull @UnknownSignedness Object target) {
       return target instanceof Double ? parent.indexOf((Double) target) : -1;
     }
 
     @Override
-    public @GTENegativeOne int lastIndexOf(@CheckForNull Object target) {
+    public @GTENegativeOne int lastIndexOf(@CheckForNull @UnknownSignedness Object target) {
       return target instanceof Double ? parent.lastIndexOf((Double) target) : -1;
     }
 
@@ -575,7 +579,7 @@ public Spliterator<Double> spliterator() {
      * therefore i is an index for parent.array
      */
     @SuppressWarnings("upperbound:array.access.unsafe.high") // index incremented in for-each over list of same length
-    public boolean equals(@CheckForNull Object object) {
+    public boolean equals(@CheckForNull @UnknownSignedness Object object) {
       if (object instanceof AsList) {
         AsList that = (AsList) object;
         return this.parent.equals(that.parent);
diff --git a/guava/src/com/google/common/primitives/ImmutableIntArray.java b/guava/src/com/google/common/primitives/ImmutableIntArray.java
index 939c6bd5ec38..46b5a127e346 100644
--- a/guava/src/com/google/common/primitives/ImmutableIntArray.java
+++ b/guava/src/com/google/common/primitives/ImmutableIntArray.java
@@ -46,7 +46,10 @@
 import org.checkerframework.checker.index.qual.HasSubsequence;
 import org.checkerframework.checker.index.qual.LessThan;
 import org.checkerframework.checker.nullness.qual.Nullable;
+import org.checkerframework.checker.signedness.qual.Signed;
+import org.checkerframework.checker.signedness.qual.UnknownSignedness;
 import org.checkerframework.dataflow.qual.Pure;
+import org.checkerframework.framework.qual.AnnotatedFor;
 
 /**
  * An immutable array of {@code int} values, with an API resembling {@link List}.
@@ -98,6 +101,7 @@
  *
  * @since 22.0
  */
+@AnnotatedFor({"signedness"})
 @Beta
 @GwtCompatible
 @Immutable
@@ -538,18 +542,21 @@ public Integer get(@IndexFor("this") int index) {
     }
 
     @Override
-    public boolean contains(@CheckForNull Object target) {
-      return indexOf(target) >= 0;
+    @SuppressWarnings("signedness:cast.unsafe")
+    public boolean contains(@CheckForNull @UnknownSignedness Object target) {
+      return indexOf((@Signed Integer) target) >= 0;
     }
 
     @Override
-    public @GTENegativeOne int indexOf(@CheckForNull Object target) {
-      return target instanceof Integer ? parent.indexOf((Integer) target) : -1;
+    @SuppressWarnings("signedness:cast.unsafe")
+    public @GTENegativeOne int indexOf(@CheckForNull @UnknownSignedness Object target) {
+      return target instanceof Integer ? parent.indexOf((@Signed Integer) target) : -1;
     }
 
     @Override
-    public @GTENegativeOne int lastIndexOf(@CheckForNull Object target) {
-      return target instanceof Integer ? parent.lastIndexOf((Integer) target) : -1;
+    @SuppressWarnings("signedness:cast.unsafe")
+    public @GTENegativeOne int lastIndexOf(@CheckForNull @UnknownSignedness Object target) {
+      return target instanceof Integer ? parent.lastIndexOf((@Signed Integer) target) : -1;
     }
 
     @Override
@@ -570,7 +577,7 @@ public Spliterator<Integer> spliterator() {
      * therefore i is an index for parent.array
      */
     @SuppressWarnings("upperbound:array.access.unsafe.high") // index incremented in for-each over list of same length
-    public boolean equals(@CheckForNull Object object) {
+    public boolean equals(@CheckForNull @UnknownSignedness Object object) {
       if (object instanceof AsList) {
         AsList that = (AsList) object;
         return this.parent.equals(that.parent);
@@ -610,7 +617,7 @@ public String toString() {
    * values as this one, in the same order.
    */
   @Override
-  public boolean equals(@CheckForNull Object object) {
+  public boolean equals(@CheckForNull @UnknownSignedness Object object) {
     if (object == this) {
       return true;
     }
diff --git a/guava/src/com/google/common/primitives/ImmutableLongArray.java b/guava/src/com/google/common/primitives/ImmutableLongArray.java
index 62373067221e..aca0b470dd8a 100644
--- a/guava/src/com/google/common/primitives/ImmutableLongArray.java
+++ b/guava/src/com/google/common/primitives/ImmutableLongArray.java
@@ -46,7 +46,10 @@
 import org.checkerframework.checker.index.qual.HasSubsequence;
 import org.checkerframework.checker.index.qual.LessThan;
 import org.checkerframework.checker.nullness.qual.Nullable;
+import org.checkerframework.checker.signedness.qual.Signed;
+import org.checkerframework.checker.signedness.qual.UnknownSignedness;
 import org.checkerframework.dataflow.qual.Pure;
+import org.checkerframework.framework.qual.AnnotatedFor;
 
 /**
  * An immutable array of {@code long} values, with an API resembling {@link List}.
@@ -98,6 +101,7 @@
  *
  * @since 22.0
  */
+@AnnotatedFor({"signedness"})
 @Beta
 @GwtCompatible
 @Immutable
@@ -540,18 +544,20 @@ public Long get(@IndexFor("this") int index) {
     }
 
     @Override
-    public boolean contains(@CheckForNull Object target) {
+    public boolean contains(@CheckForNull @UnknownSignedness Object target) {
       return indexOf(target) >= 0;
     }
 
     @Override
-    public @GTENegativeOne int indexOf(@CheckForNull Object target) {
-      return target instanceof Long ? parent.indexOf((Long) target) : -1;
+    @SuppressWarnings("signedness:cast.unsafe")
+    public @GTENegativeOne int indexOf(@CheckForNull @UnknownSignedness Object target) {
+      return target instanceof Long ? parent.indexOf((@Signed Long) target) : -1;
     }
 
     @Override
-    public @GTENegativeOne int lastIndexOf(@CheckForNull Object target) {
-      return target instanceof Long ? parent.lastIndexOf((Long) target) : -1;
+    @SuppressWarnings("signedness:cast.unsafe")
+    public @GTENegativeOne int lastIndexOf(@CheckForNull @UnknownSignedness Object target) {
+      return target instanceof Long ? parent.lastIndexOf((@Signed Long) target) : -1;
     }
 
     @Override
@@ -572,7 +578,7 @@ public Spliterator<Long> spliterator() {
      * therefore i is an index for parent.array
      */
     @SuppressWarnings("upperbound:array.access.unsafe.high") // index incremented in for-each over list of same length
-    public boolean equals(@CheckForNull Object object) {
+    public boolean equals(@CheckForNull @UnknownSignedness Object object) {
       if (object instanceof AsList) {
         AsList that = (AsList) object;
         return this.parent.equals(that.parent);
diff --git a/guava/src/com/google/common/primitives/Ints.java b/guava/src/com/google/common/primitives/Ints.java
index 2a0b096d519b..d20896f6d0b4 100644
--- a/guava/src/com/google/common/primitives/Ints.java
+++ b/guava/src/com/google/common/primitives/Ints.java
@@ -46,8 +46,11 @@
 import org.checkerframework.checker.index.qual.HasSubsequence;
 import org.checkerframework.checker.index.qual.LessThan;
 import org.checkerframework.checker.nullness.qual.Nullable;
+import org.checkerframework.checker.signedness.qual.Signed;
+import org.checkerframework.checker.signedness.qual.UnknownSignedness;
 import org.checkerframework.common.value.qual.IntRange;
 import org.checkerframework.common.value.qual.MinLen;
+import org.checkerframework.framework.qual.AnnotatedFor;
 
 /**
  * Static utility methods pertaining to {@code int} primitives, that are not already found in either
@@ -59,6 +62,7 @@
  * @author Kevin Bourrillion
  * @since 1.0
  */
+@AnnotatedFor({"signedness"})
 @GwtCompatible(emulated = true)
 @ElementTypesAreNonnullByDefault
 public final class Ints extends IntsMethodsForWeb {
@@ -625,16 +629,18 @@ public Spliterator.OfInt spliterator() {
     }
 
     @Override
-    public boolean contains(@CheckForNull Object target) {
+    @SuppressWarnings("signedness:cast.unsafe")
+    public boolean contains(@CheckForNull @UnknownSignedness Object target) {
       // Overridden to prevent a ton of boxing
-      return (target instanceof Integer) && Ints.indexOf(array, (Integer) target, start, end) != -1;
+      return (target instanceof Integer) && Ints.indexOf(array, (@Signed Integer) target, start, end) != -1;
     }
 
     @Override
-    public @IndexOrLow("this") int indexOf(@CheckForNull Object target) {
+    @SuppressWarnings("signedness:cast.unsafe")
+    public @IndexOrLow("this") int indexOf(@CheckForNull @UnknownSignedness Object target) {
       // Overridden to prevent a ton of boxing
       if (target instanceof Integer) {
-        int i = Ints.indexOf(array, (Integer) target, start, end);
+        int i = Ints.indexOf(array, (@Signed Integer) target, start, end);
         if (i >= 0) {
           return i - start;
         }
@@ -643,10 +649,11 @@ public boolean contains(@CheckForNull Object target) {
     }
 
     @Override
-    public @IndexOrLow("this")int lastIndexOf(@CheckForNull Object target) {
+    @SuppressWarnings("signedness:cast.unsafe")
+    public @IndexOrLow("this")int lastIndexOf(@CheckForNull @UnknownSignedness Object target) {
       // Overridden to prevent a ton of boxing
       if (target instanceof Integer) {
-        int i = Ints.lastIndexOf(array, (Integer) target, start, end);
+        int i = Ints.lastIndexOf(array, (@Signed Integer) target, start, end);
         if (i >= 0) {
           return i - start;
         }
@@ -675,7 +682,7 @@ public List<Integer> subList(@IndexOrHigh("this") int fromIndex, @IndexOrHigh("t
     }
 
     @Override
-    public boolean equals(@CheckForNull Object object) {
+    public boolean equals(@CheckForNull @UnknownSignedness Object object) {
       if (object == this) {
         return true;
       }
diff --git a/guava/src/com/google/common/primitives/Longs.java b/guava/src/com/google/common/primitives/Longs.java
index 516077674ef7..66f440e98d0d 100644
--- a/guava/src/com/google/common/primitives/Longs.java
+++ b/guava/src/com/google/common/primitives/Longs.java
@@ -44,9 +44,11 @@
 import org.checkerframework.checker.index.qual.HasSubsequence;
 import org.checkerframework.checker.index.qual.LessThan;
 import org.checkerframework.checker.signedness.qual.Signed;
+import org.checkerframework.checker.signedness.qual.UnknownSignedness;
 import org.checkerframework.checker.nullness.qual.Nullable;
 import org.checkerframework.common.value.qual.IntRange;
 import org.checkerframework.common.value.qual.MinLen;
+import org.checkerframework.framework.qual.AnnotatedFor;
 
 /**
  * Static utility methods pertaining to {@code long} primitives, that are not already found in
@@ -58,6 +60,7 @@
  * @author Kevin Bourrillion
  * @since 1.0
  */
+@AnnotatedFor({"signedness"})
 @GwtCompatible
 @ElementTypesAreNonnullByDefault
 public final class Longs {
@@ -725,16 +728,18 @@ public Spliterator.OfLong spliterator() {
     }
 
     @Override
-    public boolean contains(@CheckForNull Object target) {
+    @SuppressWarnings("signedness:cast.unsafe")
+    public boolean contains(@CheckForNull @UnknownSignedness Object target) {
       // Overridden to prevent a ton of boxing
-      return (target instanceof Long) && Longs.indexOf(array, (Long) target, start, end) != -1;
+      return (target instanceof Long) && Longs.indexOf(array, (@Signed Long) target, start, end) != -1;
     }
 
     @Override
-    public @IndexOrLow("this") int indexOf(@CheckForNull Object target) {
+    @SuppressWarnings("signedness:cast.unsafe")
+    public @IndexOrLow("this") int indexOf(@CheckForNull @UnknownSignedness Object target) {
       // Overridden to prevent a ton of boxing
       if (target instanceof Long) {
-        int i = Longs.indexOf(array, (Long) target, start, end);
+        int i = Longs.indexOf(array, (@Signed Long) target, start, end);
         if (i >= 0) {
           return i - start;
         }
@@ -743,10 +748,11 @@ public boolean contains(@CheckForNull Object target) {
     }
 
     @Override
-    public @IndexOrLow("this") int lastIndexOf(@CheckForNull Object target) {
+    @SuppressWarnings("signedness:cast.unsafe")
+    public @IndexOrLow("this") int lastIndexOf(@CheckForNull @UnknownSignedness Object target) {
       // Overridden to prevent a ton of boxing
       if (target instanceof Long) {
-        int i = Longs.lastIndexOf(array, (Long) target, start, end);
+        int i = Longs.lastIndexOf(array, (@Signed Long) target, start, end);
         if (i >= 0) {
           return i - start;
         }
@@ -775,7 +781,7 @@ public List<Long> subList(@IndexOrHigh("this") int fromIndex, @IndexOrHigh("this
     }
 
     @Override
-    public boolean equals(@CheckForNull Object object) {
+    public boolean equals(@CheckForNull @UnknownSignedness Object object) {
       if (object == this) {
         return true;
       }
diff --git a/guava/src/com/google/common/primitives/ParseRequest.java b/guava/src/com/google/common/primitives/ParseRequest.java
index 7ba27d99aaaf..83ac23d270dc 100644
--- a/guava/src/com/google/common/primitives/ParseRequest.java
+++ b/guava/src/com/google/common/primitives/ParseRequest.java
@@ -16,8 +16,10 @@
 
 import com.google.common.annotations.GwtCompatible;
 import org.checkerframework.common.value.qual.IntRange;
+import org.checkerframework.framework.qual.AnnotatedFor;
 
 /** A string to be parsed as a number and the radix to interpret it in. */
+@AnnotatedFor({"signedness"})
 @GwtCompatible
 @ElementTypesAreNonnullByDefault
 final class ParseRequest {
diff --git a/guava/src/com/google/common/primitives/Shorts.java b/guava/src/com/google/common/primitives/Shorts.java
index b1ee5794903b..20218988ce2b 100644
--- a/guava/src/com/google/common/primitives/Shorts.java
+++ b/guava/src/com/google/common/primitives/Shorts.java
@@ -43,8 +43,11 @@
 import org.checkerframework.checker.index.qual.HasSubsequence;
 import org.checkerframework.checker.index.qual.LessThan;
 import org.checkerframework.checker.nullness.qual.Nullable;
+import org.checkerframework.checker.signedness.qual.Signed;
+import org.checkerframework.checker.signedness.qual.UnknownSignedness;
 import org.checkerframework.common.value.qual.IntRange;
 import org.checkerframework.common.value.qual.MinLen;
+import org.checkerframework.framework.qual.AnnotatedFor;
 
 /**
  * Static utility methods pertaining to {@code short} primitives, that are not already found in
@@ -56,6 +59,7 @@
  * @author Kevin Bourrillion
  * @since 1.0
  */
+@AnnotatedFor({"signedness"})
 @GwtCompatible(emulated = true)
 @ElementTypesAreNonnullByDefault
 public final class Shorts extends ShortsMethodsForWeb {
@@ -617,18 +621,19 @@ public Short get(@IndexFor("this") int index) {
     }
 
     @Override
-    public boolean contains(@CheckForNull Object target) {
+    @SuppressWarnings("signedness:cast.unsafe")
+    public boolean contains(@CheckForNull @UnknownSignedness Object target) {
       // Overridden to prevent a ton of boxing
-      return (target instanceof Short) && Shorts.indexOf(array, (Short) target, start, end) != -1;
+      return (target instanceof Short) && Shorts.indexOf(array, (@Signed Short) target, start, end) != -1;
     }
 
 
     @Override
-    @SuppressWarnings("lowerbound:return")
-    public @IndexOrLow("this") int indexOf(@CheckForNull Object target) {
+    @SuppressWarnings("signedness:cast.unsafe")
+    public @IndexOrLow("this") int indexOf(@CheckForNull @UnknownSignedness Object target) {
       // Overridden to prevent a ton of boxing
       if (target instanceof Short) {
-        int i = Shorts.indexOf(array, (Short) target, start, end);
+        int i = Shorts.indexOf(array, (@Signed Short) target, start, end);
         if (i >= 0) {
           return i - start;
         }
@@ -637,11 +642,11 @@ public boolean contains(@CheckForNull Object target) {
     }
 
     @Override
-    @SuppressWarnings("lowerbound:return")
-    public @IndexOrLow("this") int lastIndexOf(@CheckForNull Object target) {
+    @SuppressWarnings("signedness:cast.unsafe")
+    public @IndexOrLow("this") int lastIndexOf(@CheckForNull @UnknownSignedness Object target) {
       // Overridden to prevent a ton of boxing
       if (target instanceof Short) {
-        int i = Shorts.lastIndexOf(array, (Short) target, start, end);
+        int i = Shorts.lastIndexOf(array, (@Signed Short) target, start, end);
         if (i >= 0) {
           return i - start;
         }
@@ -670,7 +675,7 @@ public List<Short> subList(@IndexOrHigh("this") int fromIndex, @IndexOrHigh("thi
     }
 
     @Override
-    public boolean equals(@CheckForNull Object object) {
+    public boolean equals(@CheckForNull @UnknownSignedness Object object) {
       if (object == this) {
         return true;
       }
diff --git a/guava/src/com/google/common/primitives/UnsignedBytes.java b/guava/src/com/google/common/primitives/UnsignedBytes.java
index b4048cd74a99..71e19885841f 100644
--- a/guava/src/com/google/common/primitives/UnsignedBytes.java
+++ b/guava/src/com/google/common/primitives/UnsignedBytes.java
@@ -35,6 +35,7 @@
 import org.checkerframework.checker.signedness.qual.Unsigned;
 import org.checkerframework.common.value.qual.IntRange;
 import org.checkerframework.common.value.qual.MinLen;
+import org.checkerframework.framework.qual.AnnotatedFor;
 import sun.misc.Unsafe;
 
 /**
@@ -52,6 +53,7 @@
  * @author Louis Wasserman
  * @since 1.0
  */
+@AnnotatedFor({"signedness"})
 @GwtIncompatible
 @ElementTypesAreNonnullByDefault
 public final class UnsignedBytes {
@@ -230,6 +232,7 @@ public static String toString(@Unsigned byte x, @IntRange(from=2, to=36) int rad
    *     Byte#parseByte(String)})
    * @since 13.0
    */
+  @SuppressWarnings("signedness:return")
   @Beta
   @CanIgnoreReturnValue
   public static @Unsigned byte parseUnsignedByte(String string, @IntRange(from=2, to=36) int radix) {
@@ -375,6 +378,11 @@ public sun.misc.Unsafe run() throws Exception {
       }
 
       @Override
+      @SuppressWarnings({
+        "signedness:argument",
+        "signedness:return",
+        "signedness:shift.unsigned"
+      })
       public int compare(@Unsigned byte[] left, @Unsigned byte[] right) {
         int stride = 8;
         int minLength = Math.min(left.length, right.length);
@@ -468,6 +476,7 @@ public String toString() {
     }
   }
 
+  @SuppressWarnings("signedness:return")
   private static @PolySigned byte flip(@PolySigned byte b) {
     return (byte) (b ^ 0x80);
   }
@@ -488,6 +497,7 @@ public static void sort(@Unsigned byte[] array) {
    *
    * @since 23.1
    */
+  @SuppressWarnings("signedness:argument")
   public static void sort(@Unsigned byte[] array, @IndexOrHigh("#1") int fromIndex, @IndexOrHigh("#1") int toIndex) {
     checkNotNull(array);
     checkPositionIndexes(fromIndex, toIndex, array.length);
@@ -517,6 +527,7 @@ public static void sortDescending(@Unsigned byte[] array) {
    *
    * @since 23.1
    */
+  @SuppressWarnings("signedness:argument")
   public static void sortDescending(@Unsigned byte[] array, @IndexOrHigh("#1") int fromIndex, @IndexOrHigh("#1") int toIndex) {
     checkNotNull(array);
     checkPositionIndexes(fromIndex, toIndex, array.length);
diff --git a/guava/src/com/google/common/primitives/UnsignedInteger.java b/guava/src/com/google/common/primitives/UnsignedInteger.java
index 518cc02e6f66..29a7095e2a2c 100644
--- a/guava/src/com/google/common/primitives/UnsignedInteger.java
+++ b/guava/src/com/google/common/primitives/UnsignedInteger.java
@@ -29,6 +29,7 @@
 import org.checkerframework.checker.nullness.qual.Nullable;
 import org.checkerframework.common.value.qual.IntRange;
 import org.checkerframework.common.value.qual.PolyValue;
+import org.checkerframework.framework.qual.AnnotatedFor;
 
 /**
  * A wrapper class for unsigned {@code int} values, supporting arithmetic operations.
@@ -43,6 +44,7 @@
  * @author Louis Wasserman
  * @since 11.0
  */
+@AnnotatedFor({"signedness"})
 @GwtCompatible(emulated = true)
 @ElementTypesAreNonnullByDefault
 public final class UnsignedInteger extends Number implements Comparable<UnsignedInteger> {
@@ -118,6 +120,7 @@ public static UnsignedInteger valueOf(String string) {
    * @throws NumberFormatException if the string does not contain a parsable unsigned {@code int}
    *     value
    */
+  @SuppressWarnings("signedness:argument")
   public static UnsignedInteger valueOf(String string, @IntRange(from=2, to=36) int radix) {
     return fromIntBits(UnsignedInts.parseUnsignedInt(string, radix));
   }
@@ -160,6 +163,7 @@ public UnsignedInteger times(UnsignedInteger val) {
    * @throws ArithmeticException if {@code val} is zero
    * @since 14.0
    */
+  @SuppressWarnings("signedness:argument")
   public UnsignedInteger dividedBy(UnsignedInteger val) {
     return fromIntBits(UnsignedInts.divide(value, checkNotNull(val).value));
   }
@@ -170,6 +174,7 @@ public UnsignedInteger dividedBy(UnsignedInteger val) {
    * @throws ArithmeticException if {@code val} is zero
    * @since 14.0
    */
+  @SuppressWarnings("signedness:argument")
   public UnsignedInteger mod(UnsignedInteger val) {
     return fromIntBits(UnsignedInts.remainder(value, checkNotNull(val).value));
   }
@@ -224,6 +229,7 @@ public BigInteger bigIntegerValue() {
    * other}.
    */
   @Override
+  @SuppressWarnings("signedness:argument")
   public int compareTo(UnsignedInteger other) {
     checkNotNull(other);
     return compare(value, other.value);
@@ -254,6 +260,7 @@ public String toString() {
    * {@code radix < Character.MIN_RADIX} or {@code radix > Character.MAX_RADIX}, the radix {@code
    * 10} is used.
    */
+  @SuppressWarnings("signedness:argument")
   public String toString(@IntRange(from=2, to=36) int radix) {
     return UnsignedInts.toString(value, radix);
   }
diff --git a/guava/src/com/google/common/primitives/UnsignedInts.java b/guava/src/com/google/common/primitives/UnsignedInts.java
index 2cde48586ddf..c1eb66a0b77e 100644
--- a/guava/src/com/google/common/primitives/UnsignedInts.java
+++ b/guava/src/com/google/common/primitives/UnsignedInts.java
@@ -32,6 +32,7 @@
 import org.checkerframework.checker.signedness.qual.Unsigned;
 import org.checkerframework.checker.signedness.qual.UnknownSignedness;
 import org.checkerframework.checker.signedness.qual.SignedPositive;
+import org.checkerframework.framework.qual.AnnotatedFor;
 
 /**
  * Static utility methods pertaining to {@code int} primitives that interpret values as
@@ -54,6 +55,7 @@
  * @author Louis Wasserman
  * @since 11.0
  */
+@AnnotatedFor({"signedness"})
 @Beta
 @GwtCompatible
 @ElementTypesAreNonnullByDefault
@@ -62,6 +64,7 @@ public final class UnsignedInts {
 
   private UnsignedInts() {}
 
+  @SuppressWarnings("signedness:return")
   static @PolySigned int flip(@PolySigned int value) {
     return value ^ Integer.MIN_VALUE;
   }
@@ -77,6 +80,7 @@ private UnsignedInts() {}
    * @return a negative value if {@code a} is less than {@code b}; a positive value if {@code a} is
    *     greater than {@code b}; or zero if they are equal
    */
+  @SuppressWarnings("signedness:argument")
   public static int compare(@Unsigned int a, @Unsigned int b) {
     return Ints.compare(flip(a), flip(b));
   }
@@ -100,7 +104,9 @@ public static int compare(@Unsigned int a, @Unsigned int b) {
    *     2<sup>32</sup>
    * @since 21.0
    */
-  public static @Unsigned int checkedCast(@IntRange(from = 0, to = (2L << 32) - 1) long value) {
+  // (long value) was originally annotated (@IntRange(from = 0, to = (2L << 32) - 1) long value)
+  // but that caused too many checker warnings.
+  public static @Unsigned int checkedCast(long value) {
     checkArgument((value >> Integer.SIZE) == 0, "out of range: %s", value);
     return (int) value;
   }
@@ -132,6 +138,7 @@ public static int compare(@Unsigned int a, @Unsigned int b) {
    *     the array according to {@link #compare}
    * @throws IllegalArgumentException if {@code array} is empty
    */
+  @SuppressWarnings("signedness:comparison.unsignedlhs")
   public static @Unsigned int min(@Unsigned int @MinLen(1)... array) {
     checkArgument(array.length > 0);
     int min = flip(array[0]);
@@ -152,6 +159,7 @@ public static int compare(@Unsigned int a, @Unsigned int b) {
    *     in the array according to {@link #compare}
    * @throws IllegalArgumentException if {@code array} is empty
    */
+  @SuppressWarnings("signedness:comparison.unsignedlhs")
   public static @Unsigned int max(@Unsigned int @MinLen(1)... array) {
     checkArgument(array.length > 0);
     int max = flip(array[0]);
@@ -237,6 +245,7 @@ public static void sort(@Unsigned int[] array) {
    *
    * @since 23.1
    */
+  @SuppressWarnings("signedness:argument")
   public static void sort(@Unsigned int[] array, @IndexOrHigh("#1") int fromIndex, @IndexOrHigh("#1") int toIndex) {
     checkNotNull(array);
     checkPositionIndexes(fromIndex, toIndex, array.length);
@@ -266,6 +275,7 @@ public static void sortDescending(@Unsigned int[] array) {
    *
    * @since 23.1
    */
+  @SuppressWarnings("signedness:argument")
   public static void sortDescending(@Unsigned int[] array, @IndexOrHigh("#1") int fromIndex, @IndexOrHigh("#1") int toIndex) {
     checkNotNull(array);
     checkPositionIndexes(fromIndex, toIndex, array.length);
diff --git a/guava/src/com/google/common/primitives/UnsignedLong.java b/guava/src/com/google/common/primitives/UnsignedLong.java
index e1643ca76905..848d355fde80 100644
--- a/guava/src/com/google/common/primitives/UnsignedLong.java
+++ b/guava/src/com/google/common/primitives/UnsignedLong.java
@@ -28,6 +28,7 @@
 import org.checkerframework.checker.signedness.qual.Unsigned;
 import org.checkerframework.common.value.qual.IntRange;
 import org.checkerframework.common.value.qual.PolyValue;
+import org.checkerframework.framework.qual.AnnotatedFor;
 
 /**
  * A wrapper class for unsigned {@code long} values, supporting arithmetic operations.
@@ -43,6 +44,7 @@
  * @author Colin Evans
  * @since 11.0
  */
+@AnnotatedFor({"signedness"})
 @GwtCompatible(serializable = true)
 @ElementTypesAreNonnullByDefault
 public final class UnsignedLong extends Number implements Comparable<UnsignedLong>, Serializable {
diff --git a/guava/src/com/google/common/primitives/UnsignedLongs.java b/guava/src/com/google/common/primitives/UnsignedLongs.java
index 09fcf1559d21..8a49347c3c40 100644
--- a/guava/src/com/google/common/primitives/UnsignedLongs.java
+++ b/guava/src/com/google/common/primitives/UnsignedLongs.java
@@ -420,11 +420,13 @@ private ParseOverflowDetection() {}
     static final int @MinLen(Character.MAX_RADIX + 1)[] maxValueMods = new int[Character.MAX_RADIX + 1];
     static final int @MinLen(Character.MAX_RADIX + 1)[] maxSafeDigits = new int[Character.MAX_RADIX + 1];
 
-    static {
+     // Unfortunately, cannot suppress a static initializer.
+     // @SuppressWarnings("signedness:cast.unsafe")
+     static {
       BigInteger overflow = new BigInteger("10000000000000000", 16);
       for (@IntRange(from=2, to=36) int i = Character.MIN_RADIX; i <= Character.MAX_RADIX; i++) {
-        maxValueDivs[i] = divide(MAX_VALUE, i);
-        maxValueMods[i] = (int) remainder(MAX_VALUE, i);
+        maxValueDivs[i] = (@Signed long) divide(MAX_VALUE, i);
+        maxValueMods[i] = (@Signed int) remainder(MAX_VALUE, i);
         maxSafeDigits[i] = overflow.toString(i).length() - 1;
       }
     }

From 43baa237c0aeab88ee6f82899e8a0392b4595643 Mon Sep 17 00:00:00 2001
From: Michael Ernst <mernst@cs.washington.edu>
Date: Fri, 14 Apr 2023 09:10:16 -0700
Subject: [PATCH 09/21] Reduce diffs with upstream, improve indentation

---
 .../com/google/common/base/MoreObjects.java   |  1 -
 .../src/com/google/common/base/Splitter.java  |  1 -
 .../com/google/common/cache/LongAdder.java    |  1 -
 .../google/common/collect/EnumMultiset.java   | 12 +++++------
 .../common/collect/LinkedHashMultiset.java    | 20 +++++++++----------
 .../src/com/google/common/io/ByteStreams.java |  1 -
 .../common/primitives/UnsignedLongs.java      | 12 +++++------
 7 files changed, 22 insertions(+), 26 deletions(-)

diff --git a/guava/src/com/google/common/base/MoreObjects.java b/guava/src/com/google/common/base/MoreObjects.java
index 400f56b082ac..865a9366ec17 100644
--- a/guava/src/com/google/common/base/MoreObjects.java
+++ b/guava/src/com/google/common/base/MoreObjects.java
@@ -21,7 +21,6 @@
 import java.lang.reflect.Array;
 import java.util.Arrays;
 import java.util.Collection;
-import java.util.logging.Logger;
 import java.util.Map;
 import java.util.OptionalDouble;
 import java.util.OptionalInt;
diff --git a/guava/src/com/google/common/base/Splitter.java b/guava/src/com/google/common/base/Splitter.java
index b9a7be2e6daa..1a3cacca25e6 100644
--- a/guava/src/com/google/common/base/Splitter.java
+++ b/guava/src/com/google/common/base/Splitter.java
@@ -30,7 +30,6 @@
 import java.util.stream.Stream;
 import java.util.stream.StreamSupport;
 import javax.annotation.CheckForNull;
-
 import org.checkerframework.checker.index.qual.GTENegativeOne;
 import org.checkerframework.checker.index.qual.IndexOrHigh;
 import org.checkerframework.checker.index.qual.LTEqLengthOf;
diff --git a/guava/src/com/google/common/cache/LongAdder.java b/guava/src/com/google/common/cache/LongAdder.java
index 1ca392e81bfe..ba9e72029c85 100644
--- a/guava/src/com/google/common/cache/LongAdder.java
+++ b/guava/src/com/google/common/cache/LongAdder.java
@@ -17,7 +17,6 @@
 import java.io.ObjectOutputStream;
 import java.io.Serializable;
 import java.util.concurrent.atomic.AtomicLong;
-
 import org.checkerframework.common.value.qual.PolyValue;
 
 /**
diff --git a/guava/src/com/google/common/collect/EnumMultiset.java b/guava/src/com/google/common/collect/EnumMultiset.java
index 8e5136baa877..623fed762782 100644
--- a/guava/src/com/google/common/collect/EnumMultiset.java
+++ b/guava/src/com/google/common/collect/EnumMultiset.java
@@ -322,11 +322,11 @@ private void readObject(ObjectInputStream stream) throws IOException, ClassNotFo
   @GwtIncompatible // Not needed in emulated source
   private static final long serialVersionUID = 0;
 
-@Pure
-@Override
-public boolean contains(@Nullable Object arg0) { return super.contains(arg0); }
+  @Pure
+  @Override
+  public boolean contains(@Nullable Object arg0) { return super.contains(arg0); }
 
-@Pure
-@Override
-public boolean containsAll(Collection<?> arg0) { return super.containsAll(arg0); }
+  @Pure
+  @Override
+  public boolean containsAll(Collection<?> arg0) { return super.containsAll(arg0); }
 }
diff --git a/guava/src/com/google/common/collect/LinkedHashMultiset.java b/guava/src/com/google/common/collect/LinkedHashMultiset.java
index 2122918b53e2..d4a046816ab4 100644
--- a/guava/src/com/google/common/collect/LinkedHashMultiset.java
+++ b/guava/src/com/google/common/collect/LinkedHashMultiset.java
@@ -106,17 +106,17 @@ private void readObject(ObjectInputStream stream) throws IOException, ClassNotFo
   @GwtIncompatible // not needed in emulated source
   private static final long serialVersionUID = 0;
 
-@Pure
-@Override
-public boolean contains(@Nullable Object arg0) { return super.contains(arg0); }
+  @Pure
+  @Override
+  public boolean contains(@Nullable Object arg0) { return super.contains(arg0); }
 
-@Override
-public int count(@Nullable Object arg0) { return super.count(arg0); }
+  @Override
+  public int count(@Nullable Object arg0) { return super.count(arg0); }
 
-@Override
-public int remove(@Nullable Object arg0, int arg1) { return super.remove(arg0, arg1); }
+  @Override
+  public int remove(@Nullable Object arg0, int arg1) { return super.remove(arg0, arg1); }
 
-@Pure
-@Override
-public boolean containsAll(Collection<?> arg0) { return super.containsAll(arg0); }
+  @Pure
+  @Override
+  public boolean containsAll(Collection<?> arg0) { return super.containsAll(arg0); }
 }
diff --git a/guava/src/com/google/common/io/ByteStreams.java b/guava/src/com/google/common/io/ByteStreams.java
index cb388e82e1b1..3a9b900f7f4b 100644
--- a/guava/src/com/google/common/io/ByteStreams.java
+++ b/guava/src/com/google/common/io/ByteStreams.java
@@ -42,7 +42,6 @@
 import java.nio.channels.WritableByteChannel;
 import java.util.ArrayDeque;
 import java.util.Arrays;
-import java.util.Deque;
 import java.util.Queue;
 import javax.annotation.CheckForNull;
 import org.checkerframework.checker.index.qual.GTENegativeOne;
diff --git a/guava/src/com/google/common/primitives/UnsignedLongs.java b/guava/src/com/google/common/primitives/UnsignedLongs.java
index 8a49347c3c40..579da3f08314 100644
--- a/guava/src/com/google/common/primitives/UnsignedLongs.java
+++ b/guava/src/com/google/common/primitives/UnsignedLongs.java
@@ -25,11 +25,11 @@
 import java.util.Arrays;
 import java.util.Comparator;
 import org.checkerframework.checker.index.qual.IndexOrHigh;
-import org.checkerframework.common.value.qual.IntRange;
-import org.checkerframework.common.value.qual.MinLen;
-import org.checkerframework.checker.signedness.qual.Signed;
 import org.checkerframework.checker.signedness.qual.PolySigned;
+import org.checkerframework.checker.signedness.qual.Signed;
 import org.checkerframework.checker.signedness.qual.Unsigned;
+import org.checkerframework.common.value.qual.IntRange;
+import org.checkerframework.common.value.qual.MinLen;
 import org.checkerframework.framework.qual.AnnotatedFor;
 
 /**
@@ -420,9 +420,9 @@ private ParseOverflowDetection() {}
     static final int @MinLen(Character.MAX_RADIX + 1)[] maxValueMods = new int[Character.MAX_RADIX + 1];
     static final int @MinLen(Character.MAX_RADIX + 1)[] maxSafeDigits = new int[Character.MAX_RADIX + 1];
 
-     // Unfortunately, cannot suppress a static initializer.
-     // @SuppressWarnings("signedness:cast.unsafe")
-     static {
+    // Unfortunately, cannot suppress a static initializer.
+    // @SuppressWarnings("signedness:cast.unsafe")
+    static {
       BigInteger overflow = new BigInteger("10000000000000000", 16);
       for (@IntRange(from=2, to=36) int i = Character.MIN_RADIX; i <= Character.MAX_RADIX; i++) {
         maxValueDivs[i] = (@Signed long) divide(MAX_VALUE, i);

From 547e599bda0842f58296dcb78d9dd3495d5794d4 Mon Sep 17 00:00:00 2001
From: Michael Ernst <mernst@cs.washington.edu>
Date: Fri, 14 Apr 2023 11:57:41 -0700
Subject: [PATCH 10/21] Add justifications for warning suppressions

---
 .../common/primitives/UnsignedInts.java       | 20 +++++++++----------
 1 file changed, 10 insertions(+), 10 deletions(-)

diff --git a/guava/src/com/google/common/primitives/UnsignedInts.java b/guava/src/com/google/common/primitives/UnsignedInts.java
index c1eb66a0b77e..eed54ad34d51 100644
--- a/guava/src/com/google/common/primitives/UnsignedInts.java
+++ b/guava/src/com/google/common/primitives/UnsignedInts.java
@@ -26,12 +26,12 @@
 import org.checkerframework.checker.index.qual.IndexOrHigh;
 import org.checkerframework.checker.index.qual.NonNegative;
 import org.checkerframework.checker.index.qual.Positive;
-import org.checkerframework.common.value.qual.IntRange;
-import org.checkerframework.common.value.qual.MinLen;
 import org.checkerframework.checker.signedness.qual.PolySigned;
-import org.checkerframework.checker.signedness.qual.Unsigned;
-import org.checkerframework.checker.signedness.qual.UnknownSignedness;
 import org.checkerframework.checker.signedness.qual.SignedPositive;
+import org.checkerframework.checker.signedness.qual.UnknownSignedness;
+import org.checkerframework.checker.signedness.qual.Unsigned;
+import org.checkerframework.common.value.qual.IntRange;
+import org.checkerframework.common.value.qual.MinLen;
 import org.checkerframework.framework.qual.AnnotatedFor;
 
 /**
@@ -64,7 +64,7 @@ public final class UnsignedInts {
 
   private UnsignedInts() {}
 
-  @SuppressWarnings("signedness:return")
+  @SuppressWarnings("signedness:return") // https://github.com/typetools/checker-framework/issues/5773
   static @PolySigned int flip(@PolySigned int value) {
     return value ^ Integer.MIN_VALUE;
   }
@@ -80,7 +80,7 @@ private UnsignedInts() {}
    * @return a negative value if {@code a} is less than {@code b}; a positive value if {@code a} is
    *     greater than {@code b}; or zero if they are equal
    */
-  @SuppressWarnings("signedness:argument")
+  @SuppressWarnings("signedness:argument") // comparison of bit-flipped values
   public static int compare(@Unsigned int a, @Unsigned int b) {
     return Ints.compare(flip(a), flip(b));
   }
@@ -104,7 +104,7 @@ public static int compare(@Unsigned int a, @Unsigned int b) {
    *     2<sup>32</sup>
    * @since 21.0
    */
-  // (long value) was originally annotated (@IntRange(from = 0, to = (2L << 32) - 1) long value)
+  // "(long value)" was originally "(@IntRange(from = 0, to = (2L << 32) - 1) long value)"
   // but that caused too many checker warnings.
   public static @Unsigned int checkedCast(long value) {
     checkArgument((value >> Integer.SIZE) == 0, "out of range: %s", value);
@@ -138,7 +138,7 @@ public static int compare(@Unsigned int a, @Unsigned int b) {
    *     the array according to {@link #compare}
    * @throws IllegalArgumentException if {@code array} is empty
    */
-  @SuppressWarnings("signedness:comparison.unsignedlhs")
+  @SuppressWarnings("signedness:comparison.unsignedlhs") // comparison of bit-flipped values
   public static @Unsigned int min(@Unsigned int @MinLen(1)... array) {
     checkArgument(array.length > 0);
     int min = flip(array[0]);
@@ -159,7 +159,7 @@ public static int compare(@Unsigned int a, @Unsigned int b) {
    *     in the array according to {@link #compare}
    * @throws IllegalArgumentException if {@code array} is empty
    */
-  @SuppressWarnings("signedness:comparison.unsignedlhs")
+  @SuppressWarnings("signedness:comparison.unsignedlhs") // comparison of bit-flipped values
   public static @Unsigned int max(@Unsigned int @MinLen(1)... array) {
     checkArgument(array.length > 0);
     int max = flip(array[0]);
@@ -245,7 +245,7 @@ public static void sort(@Unsigned int[] array) {
    *
    * @since 23.1
    */
-  @SuppressWarnings("signedness:argument")
+  @SuppressWarnings("signedness:argument") // comparison of bit-flipped values
   public static void sort(@Unsigned int[] array, @IndexOrHigh("#1") int fromIndex, @IndexOrHigh("#1") int toIndex) {
     checkNotNull(array);
     checkPositionIndexes(fromIndex, toIndex, array.length);

From 6d179dd6a8d7aa31eed761927906601cb2813f7c Mon Sep 17 00:00:00 2001
From: Mark Roberts <markro49@users.noreply.github.com>
Date: Wed, 26 Apr 2023 15:30:05 -0700
Subject: [PATCH 11/21] fix 'cannot override' warnings - part 1 (#70)

Co-authored-by: Michael Ernst <mernst@cs.washington.edu>
---
 guava/pom.xml                                 |  2 +-
 guava/src/com/google/common/base/Present.java |  4 +-
 .../com/google/common/cache/LocalCache.java   | 42 +++++------
 .../google/common/collect/AbstractBiMap.java  |  3 +-
 .../collect/AbstractMapBasedMultimap.java     | 25 ++++---
 .../common/collect/AbstractMultimap.java      |  5 +-
 .../common/collect/AbstractMultiset.java      |  7 +-
 .../common/collect/AbstractNavigableMap.java  |  3 +-
 .../google/common/collect/AbstractTable.java  |  7 +-
 .../google/common/collect/Collections2.java   | 17 +++--
 .../google/common/collect/CompactHashMap.java | 17 ++---
 .../google/common/collect/CompactHashSet.java |  6 +-
 .../common/collect/CompactLinkedHashMap.java  |  5 +-
 .../common/collect/CompactLinkedHashSet.java  |  3 +-
 .../common/collect/DescendingMultiset.java    |  3 +-
 .../common/collect/ForwardingCollection.java  | 17 ++---
 .../google/common/collect/ForwardingMap.java  |  9 ++-
 .../common/collect/ForwardingMultiset.java    |  3 +-
 .../google/common/collect/ForwardingSet.java  |  3 +-
 .../common/collect/ImmutableAsList.java       |  4 +-
 .../google/common/collect/ImmutableBiMap.java |  5 +-
 .../common/collect/ImmutableCollection.java   | 13 ++--
 .../google/common/collect/ImmutableList.java  | 15 ++--
 .../google/common/collect/ImmutableMap.java   | 17 +++--
 .../common/collect/ImmutableMapEntrySet.java  |  3 +-
 .../common/collect/ImmutableMultimap.java     |  7 +-
 .../common/collect/ImmutableMultiset.java     |  9 ++-
 .../google/common/collect/ImmutableSet.java   |  3 +-
 .../common/collect/ImmutableSetMultimap.java  |  3 +-
 .../common/collect/LinkedHashMultiset.java    |  3 +-
 .../src/com/google/common/collect/Lists.java  |  7 +-
 guava/src/com/google/common/collect/Maps.java | 75 ++++++++++---------
 .../com/google/common/collect/Multimaps.java  | 15 ++--
 .../com/google/common/collect/Multisets.java  | 15 ++--
 .../common/collect/RegularImmutableBiMap.java |  5 +-
 .../common/collect/RegularImmutableList.java  |  9 ++-
 .../common/collect/RegularImmutableMap.java   |  7 +-
 .../collect/RegularImmutableSortedSet.java    |  5 +-
 .../common/collect/RegularImmutableTable.java |  4 +-
 guava/src/com/google/common/collect/Sets.java | 36 +++++----
 .../google/common/collect/Synchronized.java   | 61 ++++++++-------
 .../common/graph/AbstractBaseGraph.java       |  6 +-
 .../AbstractDirectedNetworkConnections.java   |  4 +-
 .../google/common/graph/AbstractNetwork.java  |  4 +-
 .../graph/DirectedGraphConnections.java       |  8 +-
 .../google/common/graph/EdgesConnecting.java  |  4 +-
 .../google/common/graph/IncidentEdgeSet.java  |  6 +-
 .../google/common/graph/MapIteratorCache.java |  4 +-
 .../common/graph/MultiEdgesConnecting.java    |  4 +-
 .../common/hash/HashingOutputStream.java      |  7 +-
 .../common/io/FileBackedOutputStream.java     |  7 +-
 .../io/LittleEndianDataOutputStream.java      |  9 ++-
 .../reflect/MutableTypeToInstanceMap.java     |  7 +-
 .../AbstractListeningExecutorService.java     |  9 ++-
 .../concurrent/ForwardingExecutorService.java | 13 ++--
 .../ForwardingListeningExecutorService.java   |  5 +-
 .../concurrent/ListeningExecutorService.java  |  9 ++-
 .../ListeningScheduledExecutorService.java    |  3 +-
 .../common/util/concurrent/MoreExecutors.java |  3 +-
 .../concurrent/WrappingExecutorService.java   | 13 ++--
 .../WrappingScheduledExecutorService.java     |  3 +-
 61 files changed, 354 insertions(+), 276 deletions(-)

diff --git a/guava/pom.xml b/guava/pom.xml
index 5f2854e01b5c..e93151f8e12b 100644
--- a/guava/pom.xml
+++ b/guava/pom.xml
@@ -344,7 +344,7 @@
       <plugin>
         <groupId>org.apache.maven.plugins</groupId>
         <artifactId>maven-help-plugin</artifactId>
-        <version>3.1.0</version>
+        <version>3.1.1</version>
         <executions>
           <execution>
             <id>show-profiles</id>
diff --git a/guava/src/com/google/common/base/Present.java b/guava/src/com/google/common/base/Present.java
index 4e62da29e93b..9620877523df 100644
--- a/guava/src/com/google/common/base/Present.java
+++ b/guava/src/com/google/common/base/Present.java
@@ -21,6 +21,8 @@
 import java.util.Set;
 import javax.annotation.CheckForNull;
 
+import org.checkerframework.checker.nullness.qual.NonNull;
+
 /** Implementation of an {@link Optional} containing a reference. */
 @GwtCompatible
 @ElementTypesAreNonnullByDefault
@@ -70,7 +72,7 @@ public Set<T> asSet() {
   }
 
   @Override
-  public <V> Optional<V> transform(Function<? super T, V> function) {
+  public <V extends @NonNull Object> Optional<V> transform(Function<? super T, V> function) {
     return new Present<>(
         checkNotNull(
             function.apply(reference),
diff --git a/guava/src/com/google/common/cache/LocalCache.java b/guava/src/com/google/common/cache/LocalCache.java
index 56353772fc89..7bdaf3a89a5d 100644
--- a/guava/src/com/google/common/cache/LocalCache.java
+++ b/guava/src/com/google/common/cache/LocalCache.java
@@ -87,8 +87,7 @@
 import java.util.logging.Logger;
 import org.checkerframework.checker.nullness.qual.Nullable;
 import org.checkerframework.checker.signedness.qual.PolySigned;
-import org.checkerframework.checker.signedness.qual.Signed;
-import org.checkerframework.framework.qual.AnnotatedFor;
+import org.checkerframework.checker.signedness.qual.UnknownSignedness;
 
 /**
  * The concurrent hash map implementation built by {@link CacheBuilder}.
@@ -100,7 +99,6 @@
  * @author Bob Lee ({@code com.google.common.collect.MapMaker})
  * @author Doug Lea ({@code ConcurrentHashMap})
  */
-@AnnotatedFor({"signedness"})
 @SuppressWarnings({
   "GoodTime", // lots of violations (nanosecond math)
   "nullness", // too much trouble for the payoff
@@ -3705,7 +3703,7 @@ public ReferenceEntry<K, V> poll() {
 
     @Override
     @SuppressWarnings("unchecked")
-    public boolean remove(Object o) {
+    public boolean remove(@UnknownSignedness Object o) {
       ReferenceEntry<K, V> e = (ReferenceEntry<K, V>) o;
       ReferenceEntry<K, V> previous = e.getPreviousInWriteQueue();
       ReferenceEntry<K, V> next = e.getNextInWriteQueue();
@@ -3717,7 +3715,7 @@ public boolean remove(Object o) {
 
     @Override
     @SuppressWarnings("unchecked")
-    public boolean contains(Object o) {
+    public boolean contains(@UnknownSignedness Object o) {
       ReferenceEntry<K, V> e = (ReferenceEntry<K, V>) o;
       return e.getNextInWriteQueue() != NullEntry.INSTANCE;
     }
@@ -3844,7 +3842,7 @@ public ReferenceEntry<K, V> poll() {
 
     @Override
     @SuppressWarnings("unchecked")
-    public boolean remove(Object o) {
+    public boolean remove(@UnknownSignedness Object o) {
       ReferenceEntry<K, V> e = (ReferenceEntry<K, V>) o;
       ReferenceEntry<K, V> previous = e.getPreviousInAccessQueue();
       ReferenceEntry<K, V> next = e.getNextInAccessQueue();
@@ -3856,7 +3854,7 @@ public boolean remove(Object o) {
 
     @Override
     @SuppressWarnings("unchecked")
-    public boolean contains(Object o) {
+    public boolean contains(@UnknownSignedness Object o) {
       ReferenceEntry<K, V> e = (ReferenceEntry<K, V>) o;
       return e.getNextInAccessQueue() != NullEntry.INSTANCE;
     }
@@ -3957,7 +3955,7 @@ public int size() {
   }
 
   @Override
-  public @Nullable V get(@Nullable Object key) {
+  public @Nullable V get(@Nullable @UnknownSignedness Object key) {
     if (key == null) {
       return null;
     }
@@ -3984,7 +3982,7 @@ V get(K key, CacheLoader<? super K, V> loader) throws ExecutionException {
   // Only becomes available in Java 8 when it's on the interface.
   // @Override
   @Override
-  public @Nullable V getOrDefault(@Nullable Object key, @Nullable V defaultValue) {
+  public @Nullable V getOrDefault(@Nullable @UnknownSignedness Object key, @Nullable V defaultValue) {
     V result = get(key);
     return (result != null) ? result : defaultValue;
   }
@@ -4143,7 +4141,7 @@ void refresh(K key) {
   }
 
   @Override
-  public boolean containsKey(@Nullable Object key) {
+  public boolean containsKey(@Nullable @UnknownSignedness Object key) {
     // does not impact recency ordering
     if (key == null) {
       return false;
@@ -4153,7 +4151,7 @@ public boolean containsKey(@Nullable Object key) {
   }
 
   @Override
-  public boolean containsValue(@Nullable Object value) {
+  public boolean containsValue(@Nullable @UnknownSignedness Object value) {
     // does not impact recency ordering
     if (value == null) {
       return false;
@@ -4247,7 +4245,7 @@ public void putAll(Map<? extends K, ? extends V> m) {
   }
 
   @Override
-  public V remove(@Nullable Object key) {
+  public V remove(@Nullable @UnknownSignedness Object key) {
     if (key == null) {
       return null;
     }
@@ -4256,7 +4254,7 @@ public V remove(@Nullable Object key) {
   }
 
   @Override
-  public boolean remove(@Nullable Object key, @Nullable Object value) {
+  public boolean remove(@Nullable @UnknownSignedness Object key, @Nullable @UnknownSignedness Object value) {
     if (key == null || value == null) {
       return false;
     }
@@ -4532,8 +4530,8 @@ public void clear() {
     // https://code.google.com/p/android/issues/detail?id=36519 / http://r.android.com/47508
 
     @Override
-    public @PolySigned Object[] toArray(LocalCache<K,V>.AbstractCacheSet<T> this) {
-      return (@PolySigned Object[]) toArrayList(this).toArray();
+    public @PolySigned Object[] toArray() {
+      return toArrayList(this).toArray();
     }
 
     @Override
@@ -4574,12 +4572,12 @@ public Iterator<K> iterator() {
     }
 
     @Override
-    public boolean contains(Object o) {
+    public boolean contains(@UnknownSignedness Object o) {
       return LocalCache.this.containsKey(o);
     }
 
     @Override
-    public boolean remove(Object o) {
+    public boolean remove(@UnknownSignedness Object o) {
       return LocalCache.this.remove(o) != null;
     }
   }
@@ -4612,7 +4610,7 @@ public boolean removeIf(Predicate<? super V> filter) {
     }
 
     @Override
-    public boolean contains(Object o) {
+    public boolean contains(@UnknownSignedness Object o) {
       return LocalCache.this.containsValue(o);
     }
 
@@ -4620,8 +4618,8 @@ public boolean contains(Object o) {
     // https://code.google.com/p/android/issues/detail?id=36519 / http://r.android.com/47508
 
     @Override
-    public @PolySigned Object[] toArray(LocalCache<K,V>.Values this) {
-      return (@PolySigned Object[]) toArrayList(this).toArray();
+    public @PolySigned Object[] toArray() {
+      return toArrayList(this).toArray();
     }
 
     @Override
@@ -4644,7 +4642,7 @@ public boolean removeIf(Predicate<? super Entry<K, V>> filter) {
     }
 
     @Override
-    public boolean contains(Object o) {
+    public boolean contains(@UnknownSignedness Object o) {
       if (!(o instanceof Entry)) {
         return false;
       }
@@ -4659,7 +4657,7 @@ public boolean contains(Object o) {
     }
 
     @Override
-    public boolean remove(Object o) {
+    public boolean remove(@UnknownSignedness Object o) {
       if (!(o instanceof Entry)) {
         return false;
       }
diff --git a/guava/src/com/google/common/collect/AbstractBiMap.java b/guava/src/com/google/common/collect/AbstractBiMap.java
index d52dc61ae022..79c3338eee16 100644
--- a/guava/src/com/google/common/collect/AbstractBiMap.java
+++ b/guava/src/com/google/common/collect/AbstractBiMap.java
@@ -37,6 +37,7 @@
 import java.util.function.BiFunction;
 import javax.annotation.CheckForNull;
 import org.checkerframework.checker.nullness.qual.Nullable;
+import org.checkerframework.checker.nullness.qual.PolyNull;
 import org.checkerframework.dataflow.qual.Pure;
 import org.checkerframework.dataflow.qual.SideEffectFree;
 import org.checkerframework.framework.qual.AnnotatedFor;
@@ -304,7 +305,7 @@ public Iterator<V> iterator() {
     }
 
     @Override
-    public @Nullable Object[] toArray() {
+    public @PolyNull Object[] toArray() {
       return standardToArray();
     }
 
diff --git a/guava/src/com/google/common/collect/AbstractMapBasedMultimap.java b/guava/src/com/google/common/collect/AbstractMapBasedMultimap.java
index 4c5a0f0418fb..257f7376af25 100644
--- a/guava/src/com/google/common/collect/AbstractMapBasedMultimap.java
+++ b/guava/src/com/google/common/collect/AbstractMapBasedMultimap.java
@@ -46,6 +46,7 @@
 import java.util.function.BiConsumer;
 import javax.annotation.CheckForNull;
 import org.checkerframework.checker.nullness.qual.Nullable;
+import org.checkerframework.checker.signedness.qual.UnknownSignedness;
 
 /**
  * Basic implementation of the {@link Multimap} interface. This class represents a multimap as a map
@@ -401,7 +402,7 @@ public int size() {
     }
 
     @Override
-    public boolean equals(@CheckForNull Object object) {
+    public boolean equals(@CheckForNull @UnknownSignedness Object object) {
       if (object == this) {
         return true;
       }
@@ -525,7 +526,7 @@ public boolean addAll(Collection<? extends V> collection) {
     }
 
     @Override
-    public boolean contains(@CheckForNull Object o) {
+    public boolean contains(@CheckForNull @UnknownSignedness Object o) {
       refreshIfEmpty();
       return delegate.contains(o);
     }
@@ -548,7 +549,7 @@ public void clear() {
     }
 
     @Override
-    public boolean remove(@CheckForNull Object o) {
+    public boolean remove(@CheckForNull @UnknownSignedness Object o) {
       refreshIfEmpty();
       boolean changed = delegate.remove(o);
       if (changed) {
@@ -833,13 +834,13 @@ public V remove(int index) {
     }
 
     @Override
-    public int indexOf(@CheckForNull Object o) {
+    public int indexOf(@CheckForNull @UnknownSignedness Object o) {
       refreshIfEmpty();
       return getListDelegate().indexOf(o);
     }
 
     @Override
-    public int lastIndexOf(@CheckForNull Object o) {
+    public int lastIndexOf(@CheckForNull @UnknownSignedness Object o) {
       refreshIfEmpty();
       return getListDelegate().lastIndexOf(o);
     }
@@ -985,7 +986,7 @@ public Spliterator<K> spliterator() {
     }
 
     @Override
-    public boolean remove(@CheckForNull Object key) {
+    public boolean remove(@CheckForNull @UnknownSignedness Object key) {
       int count = 0;
       Collection<V> collection = map().remove(key);
       if (collection != null) {
@@ -1007,7 +1008,7 @@ public boolean containsAll(Collection<?> c) {
     }
 
     @Override
-    public boolean equals(@CheckForNull Object object) {
+    public boolean equals(@CheckForNull @UnknownSignedness Object object) {
       return this == object || this.map().keySet().equals(object);
     }
 
@@ -1357,13 +1358,13 @@ protected Set<Entry<K, Collection<V>>> createEntrySet() {
     // The following methods are included for performance.
 
     @Override
-    public boolean containsKey(@CheckForNull Object key) {
+    public boolean containsKey(@CheckForNull @UnknownSignedness Object key) {
       return Maps.safeContainsKey(submap, key);
     }
 
     @Override
     @CheckForNull
-    public Collection<V> get(@CheckForNull Object key) {
+    public Collection<V> get(@CheckForNull @UnknownSignedness Object key) {
       Collection<V> collection = Maps.safeGet(submap, key);
       if (collection == null) {
         return null;
@@ -1385,7 +1386,7 @@ public int size() {
 
     @Override
     @CheckForNull
-    public Collection<V> remove(@CheckForNull Object key) {
+    public Collection<V> remove(@CheckForNull @UnknownSignedness Object key) {
       Collection<V> collection = submap.remove(key);
       if (collection == null) {
         return null;
@@ -1447,12 +1448,12 @@ public Spliterator<Entry<K, Collection<V>>> spliterator() {
       // The following methods are included for performance.
 
       @Override
-      public boolean contains(@CheckForNull Object o) {
+      public boolean contains(@CheckForNull @UnknownSignedness Object o) {
         return Collections2.safeContains(submap.entrySet(), o);
       }
 
       @Override
-      public boolean remove(@CheckForNull Object o) {
+      public boolean remove(@CheckForNull @UnknownSignedness Object o) {
         if (!contains(o)) {
           return false;
         }
diff --git a/guava/src/com/google/common/collect/AbstractMultimap.java b/guava/src/com/google/common/collect/AbstractMultimap.java
index 2f69ff380e07..a86679037683 100644
--- a/guava/src/com/google/common/collect/AbstractMultimap.java
+++ b/guava/src/com/google/common/collect/AbstractMultimap.java
@@ -32,6 +32,7 @@
 import java.util.Spliterators;
 import javax.annotation.CheckForNull;
 import org.checkerframework.checker.nullness.qual.Nullable;
+import org.checkerframework.checker.signedness.qual.UnknownSignedness;
 import org.checkerframework.dataflow.qual.Pure;
 import org.checkerframework.dataflow.qual.SideEffectFree;
 import org.checkerframework.framework.qual.AnnotatedFor;
@@ -157,7 +158,7 @@ public int hashCode() {
 
     @Pure
     @Override
-    public boolean equals(@CheckForNull Object obj) {
+    public boolean equals(@CheckForNull @UnknownSignedness Object obj) {
       return Sets.equalsImpl(this, obj);
     }
   }
@@ -222,7 +223,7 @@ public int size() {
 
     @Pure
     @Override
-    public boolean contains(@CheckForNull Object o) {
+    public boolean contains(@CheckForNull @UnknownSignedness Object o) {
       return AbstractMultimap.this.containsValue(o);
     }
 
diff --git a/guava/src/com/google/common/collect/AbstractMultiset.java b/guava/src/com/google/common/collect/AbstractMultiset.java
index 4d9559b04938..ab0e5d5d13a9 100644
--- a/guava/src/com/google/common/collect/AbstractMultiset.java
+++ b/guava/src/com/google/common/collect/AbstractMultiset.java
@@ -28,6 +28,7 @@
 import java.util.Set;
 import javax.annotation.CheckForNull;
 import org.checkerframework.checker.nullness.qual.Nullable;
+import org.checkerframework.checker.signedness.qual.UnknownSignedness;
 import org.checkerframework.dataflow.qual.Pure;
 import org.checkerframework.dataflow.qual.SideEffectFree;
 import org.checkerframework.framework.qual.AnnotatedFor;
@@ -60,7 +61,7 @@ public boolean isEmpty() {
 
   @Pure
   @Override
-  public boolean contains(@CheckForNull Object element) {
+  public boolean contains(@CheckForNull @UnknownSignedness Object element) {
     return count(element) > 0;
   }
 
@@ -80,7 +81,7 @@ public int add(@ParametricNullness E element, int occurrences) {
 
   @CanIgnoreReturnValue
   @Override
-  public final boolean remove(@CheckForNull Object element) {
+  public final boolean remove(@CheckForNull @UnknownSignedness Object element) {
     return remove(element, 1) > 0;
   }
 
@@ -216,7 +217,7 @@ Set<Entry<E>> createEntrySet() {
    */
   @Pure
   @Override
-  public final boolean equals(@CheckForNull Object object) {
+  public final boolean equals(@CheckForNull @UnknownSignedness Object object) {
     return Multisets.equalsImpl(this, object);
   }
 
diff --git a/guava/src/com/google/common/collect/AbstractNavigableMap.java b/guava/src/com/google/common/collect/AbstractNavigableMap.java
index 47048d06ac49..962105f16ea7 100644
--- a/guava/src/com/google/common/collect/AbstractNavigableMap.java
+++ b/guava/src/com/google/common/collect/AbstractNavigableMap.java
@@ -26,6 +26,7 @@
 import java.util.SortedMap;
 import javax.annotation.CheckForNull;
 import org.checkerframework.checker.nullness.qual.Nullable;
+import org.checkerframework.checker.signedness.qual.UnknownSignedness;
 
 /**
  * Skeletal implementation of {@link NavigableMap}.
@@ -39,7 +40,7 @@ abstract class AbstractNavigableMap<K extends @Nullable Object, V extends @Nulla
 
   @Override
   @CheckForNull
-  public abstract V get(@CheckForNull Object key);
+  public abstract V get(@CheckForNull @UnknownSignedness Object key);
 
   @Override
   @CheckForNull
diff --git a/guava/src/com/google/common/collect/AbstractTable.java b/guava/src/com/google/common/collect/AbstractTable.java
index 99a121590654..8b4cc00468e7 100644
--- a/guava/src/com/google/common/collect/AbstractTable.java
+++ b/guava/src/com/google/common/collect/AbstractTable.java
@@ -27,6 +27,7 @@
 import java.util.Spliterator;
 import javax.annotation.CheckForNull;
 import org.checkerframework.checker.nullness.qual.Nullable;
+import org.checkerframework.checker.signedness.qual.UnknownSignedness;
 
 /**
  * Skeletal, implementation-agnostic implementation of the {@link Table} interface.
@@ -134,7 +135,7 @@ Set<Cell<R, C, V>> createCellSet() {
   @WeakOuter
   class CellSet extends AbstractSet<Cell<R, C, V>> {
     @Override
-    public boolean contains(@CheckForNull Object o) {
+    public boolean contains(@CheckForNull @UnknownSignedness Object o) {
       if (o instanceof Cell) {
         Cell<?, ?, ?> cell = (Cell<?, ?, ?>) o;
         Map<C, V> row = Maps.safeGet(rowMap(), cell.getRowKey());
@@ -146,7 +147,7 @@ public boolean contains(@CheckForNull Object o) {
     }
 
     @Override
-    public boolean remove(@CheckForNull Object o) {
+    public boolean remove(@CheckForNull @UnknownSignedness Object o) {
       if (o instanceof Cell) {
         Cell<?, ?, ?> cell = (Cell<?, ?, ?>) o;
         Map<C, V> row = Maps.safeGet(rowMap(), cell.getRowKey());
@@ -217,7 +218,7 @@ public Spliterator<V> spliterator() {
     }
 
     @Override
-    public boolean contains(@CheckForNull Object o) {
+    public boolean contains(@CheckForNull @UnknownSignedness Object o) {
       return containsValue(o);
     }
 
diff --git a/guava/src/com/google/common/collect/Collections2.java b/guava/src/com/google/common/collect/Collections2.java
index fc9e534c7929..d87f94314ea3 100644
--- a/guava/src/com/google/common/collect/Collections2.java
+++ b/guava/src/com/google/common/collect/Collections2.java
@@ -40,6 +40,9 @@
 import java.util.function.Consumer;
 import javax.annotation.CheckForNull;
 import org.checkerframework.checker.nullness.qual.Nullable;
+import org.checkerframework.checker.nullness.qual.PolyNull;
+import org.checkerframework.checker.signedness.qual.PolySigned;
+import org.checkerframework.checker.signedness.qual.UnknownSignedness;
 import org.checkerframework.dataflow.qual.Pure;
 import org.checkerframework.framework.qual.AnnotatedFor;
 
@@ -161,7 +164,7 @@ public void clear() {
 
     @Pure
     @Override
-    public boolean contains(@CheckForNull Object element) {
+    public boolean contains(@CheckForNull @UnknownSignedness Object element) {
       if (safeContains(unfiltered, element)) {
         @SuppressWarnings("unchecked") // element is in unfiltered, so it must be an E
         E e = (E) element;
@@ -204,7 +207,7 @@ public void forEach(Consumer<? super E> action) {
     }
 
     @Override
-    public boolean remove(@CheckForNull Object element) {
+    public boolean remove(@CheckForNull @UnknownSignedness Object element) {
       return contains(element) && unfiltered.remove(element);
     }
 
@@ -237,14 +240,14 @@ public int size() {
     }
 
     @Override
-    public @Nullable Object[] toArray() {
+    public @PolyNull @PolySigned Object[] toArray(FilteredCollection<@PolyNull @PolySigned E> this) {
       // creating an ArrayList so filtering happens once
       return Lists.newArrayList(iterator()).toArray();
     }
 
     @Override
-    @SuppressWarnings("nullness") // b/192354773 in our checker affects toArray declarations
-    public <T extends @Nullable Object> T[] toArray(T[] array) {
+    @SuppressWarnings("nullness:return")
+    public <T extends @Nullable @UnknownSignedness Object> T[] toArray(T[] array) {
       return Lists.newArrayList(iterator()).toArray(array);
     }
 
@@ -508,7 +511,7 @@ public Iterator<List<E>> iterator() {
     }
 
     @Override
-    public boolean contains(@CheckForNull Object obj) {
+    public boolean contains(@CheckForNull @UnknownSignedness Object obj) {
       if (obj instanceof List) {
         List<?> list = (List<?>) obj;
         return isPermutation(inputList, list);
@@ -635,7 +638,7 @@ public Iterator<List<E>> iterator() {
     }
 
     @Override
-    public boolean contains(@CheckForNull Object obj) {
+    public boolean contains(@CheckForNull @UnknownSignedness Object obj) {
       if (obj instanceof List) {
         List<?> list = (List<?>) obj;
         return isPermutation(inputList, list);
diff --git a/guava/src/com/google/common/collect/CompactHashMap.java b/guava/src/com/google/common/collect/CompactHashMap.java
index 86359674c09b..454cc0cfb4c9 100644
--- a/guava/src/com/google/common/collect/CompactHashMap.java
+++ b/guava/src/com/google/common/collect/CompactHashMap.java
@@ -708,8 +708,7 @@ class KeySetView extends Maps.KeySet<K, V> {
     }
 
     @Override
-    //public @PolySigned Object[] toArray(CompactHashMap<@PolySigned K, @PolySigned V>.KeySetView this) {
-    public @Nullable Object[] toArray() {
+    public @PolyNull @PolySigned Object[] toArray(CompactHashMap<@PolyNull @PolySigned K, @PolyNull @PolySigned V>.KeySetView this) {
       if (needsAllocArrays()) {
         return new Object[0];
       }
@@ -721,7 +720,7 @@ class KeySetView extends Maps.KeySet<K, V> {
 
     @Override
     @SuppressWarnings("nullness") // b/192354773 in our checker affects toArray declarations
-    public <T extends @Nullable Object> T[] toArray(T[] a) {
+    public <T extends @Nullable @UnknownSignedness Object> T[] toArray(@PolyNull T[] a) {
       if (needsAllocArrays()) {
         if (a.length > 0) {
           @Nullable Object[] unsoundlyCovariantArray = a;
@@ -736,7 +735,7 @@ class KeySetView extends Maps.KeySet<K, V> {
     }
 
     @Override
-    public boolean remove(@CheckForNull Object o) {
+    public boolean remove(@CheckForNull @UnknownSignedness Object o) {
       Map<K, V> delegate = delegateOrNull();
       return (delegate != null)
           ? delegate.keySet().remove(o)
@@ -834,7 +833,7 @@ public Spliterator<Entry<K, V>> spliterator() {
     }
 
     @Override
-    public boolean contains(@CheckForNull Object o) {
+    public boolean contains(@CheckForNull @UnknownSignedness Object o) {
       Map<K, V> delegate = delegateOrNull();
       if (delegate != null) {
         return delegate.entrySet().contains(o);
@@ -847,7 +846,7 @@ public boolean contains(@CheckForNull Object o) {
     }
 
     @Override
-    public boolean remove(@CheckForNull Object o) {
+    public boolean remove(@CheckForNull @UnknownSignedness Object o) {
       Map<K, V> delegate = delegateOrNull();
       if (delegate != null) {
         return delegate.entrySet().remove(o);
@@ -971,7 +970,7 @@ public boolean isEmpty() {
   }
 
   @Override
-  public boolean containsValue(@CheckForNull Object value) {
+  public boolean containsValue(@CheckForNull @UnknownSignedness Object value) {
     Map<K, V> delegate = delegateOrNull();
     if (delegate != null) {
       return delegate.containsValue(value);
@@ -1031,7 +1030,7 @@ public Spliterator<V> spliterator() {
     }
 
     @Override
-    public @Nullable Object[] toArray() {
+    public @PolyNull @PolySigned Object[] toArray() {
       if (needsAllocArrays()) {
         return new Object[0];
       }
@@ -1043,7 +1042,7 @@ public Spliterator<V> spliterator() {
 
     @Override
     @SuppressWarnings("nullness") // b/192354773 in our checker affects toArray declarations
-    public <T extends @Nullable Object> T[] toArray(T[] a) {
+    public <T extends @Nullable @UnknownSignedness Object> T[] toArray(@PolyNull T[] a) {
       if (needsAllocArrays()) {
         if (a.length > 0) {
           @Nullable Object[] unsoundlyCovariantArray = a;
diff --git a/guava/src/com/google/common/collect/CompactHashSet.java b/guava/src/com/google/common/collect/CompactHashSet.java
index 88f62adf7b2c..ff74fd3131b6 100644
--- a/guava/src/com/google/common/collect/CompactHashSet.java
+++ b/guava/src/com/google/common/collect/CompactHashSet.java
@@ -47,6 +47,7 @@
 import java.util.function.Consumer;
 import javax.annotation.CheckForNull;
 import org.checkerframework.checker.nullness.qual.Nullable;
+import org.checkerframework.checker.nullness.qual.PolyNull;
 import org.checkerframework.checker.signedness.qual.PolySigned;
 import org.checkerframework.checker.signedness.qual.UnknownSignedness;
 
@@ -629,8 +630,7 @@ public boolean isEmpty() {
   }
 
   @Override
-  //public @PolySigned Object[] toArray(CompactHashSet<@PolySigned E> this) {
-  public @Nullable Object[] toArray() {
+  public @PolyNull @PolySigned Object[] toArray(CompactHashSet<@PolyNull @PolySigned E> this) {
     if (needsAllocArrays()) {
       return new Object[0];
     }
@@ -641,7 +641,7 @@ public boolean isEmpty() {
   @CanIgnoreReturnValue
   @Override
   @SuppressWarnings("nullness") // b/192354773 in our checker affects toArray declarations
-  public <T extends @Nullable Object> T[] toArray(T[] a) {
+  public <T extends @Nullable @UnknownSignedness Object> T[] toArray(T[] a) {
     if (needsAllocArrays()) {
       if (a.length > 0) {
         a[0] = null;
diff --git a/guava/src/com/google/common/collect/CompactLinkedHashMap.java b/guava/src/com/google/common/collect/CompactLinkedHashMap.java
index 97b3a4b1c3b9..00926dabe9c8 100644
--- a/guava/src/com/google/common/collect/CompactLinkedHashMap.java
+++ b/guava/src/com/google/common/collect/CompactLinkedHashMap.java
@@ -31,6 +31,7 @@
 import java.util.Spliterators;
 import javax.annotation.CheckForNull;
 import org.checkerframework.checker.nullness.qual.Nullable;
+import org.checkerframework.checker.nullness.qual.PolyNull;
 
 /**
  * CompactLinkedHashMap is an implementation of a Map with insertion or LRU iteration order,
@@ -244,7 +245,7 @@ Set<K> createKeySet() {
     @WeakOuter
     class KeySetImpl extends KeySetView {
       @Override
-      public @Nullable Object[] toArray() {
+      public @PolyNull Object[] toArray() {
         return ObjectArrays.toArrayImpl(this);
       }
 
@@ -267,7 +268,7 @@ Collection<V> createValues() {
     @WeakOuter
     class ValuesImpl extends ValuesView {
       @Override
-      public @Nullable Object[] toArray() {
+      public @PolyNull Object[] toArray() {
         return ObjectArrays.toArrayImpl(this);
       }
 
diff --git a/guava/src/com/google/common/collect/CompactLinkedHashSet.java b/guava/src/com/google/common/collect/CompactLinkedHashSet.java
index c1d813cdb435..05a4e3e60961 100644
--- a/guava/src/com/google/common/collect/CompactLinkedHashSet.java
+++ b/guava/src/com/google/common/collect/CompactLinkedHashSet.java
@@ -28,6 +28,7 @@
 import java.util.Spliterators;
 import javax.annotation.CheckForNull;
 import org.checkerframework.checker.nullness.qual.Nullable;
+import org.checkerframework.checker.nullness.qual.PolyNull;
 
 /**
  * CompactLinkedHashSet is an implementation of a Set, which a predictable iteration order that
@@ -233,7 +234,7 @@ int adjustAfterRemove(int indexBeforeRemove, int indexRemoved) {
   }
 
   @Override
-  public @Nullable Object[] toArray() {
+  public @PolyNull Object[] toArray() {
     return ObjectArrays.toArrayImpl(this);
   }
 
diff --git a/guava/src/com/google/common/collect/DescendingMultiset.java b/guava/src/com/google/common/collect/DescendingMultiset.java
index 7db0fbbd4916..bad3cf09e841 100644
--- a/guava/src/com/google/common/collect/DescendingMultiset.java
+++ b/guava/src/com/google/common/collect/DescendingMultiset.java
@@ -24,6 +24,7 @@
 import java.util.Set;
 import javax.annotation.CheckForNull;
 import org.checkerframework.checker.nullness.qual.Nullable;
+import org.checkerframework.checker.nullness.qual.PolyNull;
 
 /**
  * A skeleton implementation of a descending multiset. Only needs {@code forwardMultiset()} and
@@ -151,7 +152,7 @@ public Iterator<E> iterator() {
   }
 
   @Override
-  public @Nullable Object[] toArray() {
+  public @PolyNull Object[] toArray() {
     return standardToArray();
   }
 
diff --git a/guava/src/com/google/common/collect/ForwardingCollection.java b/guava/src/com/google/common/collect/ForwardingCollection.java
index f8c7e86d4008..11e71fc04b5d 100644
--- a/guava/src/com/google/common/collect/ForwardingCollection.java
+++ b/guava/src/com/google/common/collect/ForwardingCollection.java
@@ -23,6 +23,9 @@
 import java.util.Iterator;
 import javax.annotation.CheckForNull;
 import org.checkerframework.checker.nullness.qual.Nullable;
+import org.checkerframework.checker.nullness.qual.PolyNull;
+import org.checkerframework.checker.signedness.qual.PolySigned;
+import org.checkerframework.checker.signedness.qual.UnknownSignedness;
 import org.checkerframework.dataflow.qual.Pure;
 import org.checkerframework.framework.qual.AnnotatedFor;
 
@@ -68,7 +71,6 @@ public Iterator<E> iterator() {
 
   @Pure
   @Override
-  @SuppressWarnings("index:override.return")
   public int size() {
     return delegate().size();
   }
@@ -88,7 +90,7 @@ public boolean isEmpty() {
   @Pure
   @Override
   @SuppressWarnings("nullness:argument")
-  public boolean contains(@CheckForNull Object object) {
+  public boolean contains(@CheckForNull @UnknownSignedness Object object) {
     return delegate().contains(object);
   }
 
@@ -101,13 +103,12 @@ public boolean add(@ParametricNullness E element) {
   @CanIgnoreReturnValue
   @Override
   @SuppressWarnings("nullness:argument")
-  public boolean remove(@CheckForNull Object object) {
+  public boolean remove(@CheckForNull @UnknownSignedness Object object) {
     return delegate().remove(object);
   }
 
   @Pure
   @Override
-  @SuppressWarnings("nullness") // Suppressed due to the containsAll method in Collection
   public boolean containsAll(Collection<?> collection) {
     return delegate().containsAll(collection);
   }
@@ -120,7 +121,6 @@ public boolean addAll(Collection<? extends E> collection) {
 
   @CanIgnoreReturnValue
   @Override
-  @SuppressWarnings("nullness") // Suppressed due to the containsAll method in Collection
   public boolean retainAll(Collection<?> collection) {
     return delegate().retainAll(collection);
   }
@@ -131,15 +131,14 @@ public void clear() {
   }
 
   @Override
-  @SuppressWarnings("nullness") // Suppressed due to annotations of toArray
-  public @Nullable Object[] toArray() {
+  public @PolyNull @PolySigned Object[] toArray(ForwardingCollection<@PolyNull @PolySigned E> this) {
     return delegate().toArray();
   }
 
   @CanIgnoreReturnValue
   @Override
-  @SuppressWarnings("nullness") // b/192354773 in our checker affects toArray declarations
-  public <T extends @Nullable Object> T[] toArray(T[] array) {
+  @SuppressWarnings("nullness:return")
+  public <T extends @Nullable @UnknownSignedness Object> T[] toArray(T[] array) {
     return delegate().toArray(array);
   }
 
diff --git a/guava/src/com/google/common/collect/ForwardingMap.java b/guava/src/com/google/common/collect/ForwardingMap.java
index 319027c4440c..73856b92746c 100644
--- a/guava/src/com/google/common/collect/ForwardingMap.java
+++ b/guava/src/com/google/common/collect/ForwardingMap.java
@@ -26,6 +26,7 @@
 import java.util.Set;
 import javax.annotation.CheckForNull;
 import org.checkerframework.checker.nullness.qual.Nullable;
+import org.checkerframework.checker.signedness.qual.UnknownSignedness;
 import org.checkerframework.dataflow.qual.Pure;
 import org.checkerframework.dataflow.qual.SideEffectFree;
 import org.checkerframework.framework.qual.AnnotatedFor;
@@ -88,7 +89,7 @@ public boolean isEmpty() {
   @Override
   @SuppressWarnings("nullness:argument") // Suppressed due to annotations on remove in Java.Map
   @CheckForNull
-  public V remove(@CheckForNull Object key) {
+  public V remove(@CheckForNull @UnknownSignedness Object key) {
     return delegate().remove(key);
   }
 
@@ -100,21 +101,21 @@ public void clear() {
   @Pure
   @Override
   @SuppressWarnings("nullness:argument") // Suppressed due to annotations on containsKey in Java.Map
-  public boolean containsKey(@CheckForNull Object key) {
+  public boolean containsKey(@CheckForNull @UnknownSignedness Object key) {
     return delegate().containsKey(key);
   }
 
   @Pure
   @Override
   @SuppressWarnings("nullness:argument") // Suppressed due to annotations on containsValue in Java.Map
-  public boolean containsValue(@CheckForNull Object value) {
+  public boolean containsValue(@CheckForNull @UnknownSignedness Object value) {
     return delegate().containsValue(value);
   }
 
   @Override
   @SuppressWarnings("nullness:argument") // Suppressed due to annotations on get in Java.Map
   @CheckForNull
-  public V get(@CheckForNull Object key) {
+  public V get(@CheckForNull @UnknownSignedness Object key) {
     return delegate().get(key);
   }
 
diff --git a/guava/src/com/google/common/collect/ForwardingMultiset.java b/guava/src/com/google/common/collect/ForwardingMultiset.java
index 72bc3cf6406f..5d6a7d04dbd3 100644
--- a/guava/src/com/google/common/collect/ForwardingMultiset.java
+++ b/guava/src/com/google/common/collect/ForwardingMultiset.java
@@ -25,6 +25,7 @@
 import java.util.Set;
 import javax.annotation.CheckForNull;
 import org.checkerframework.checker.nullness.qual.Nullable;
+import org.checkerframework.checker.signedness.qual.UnknownSignedness;
 import org.checkerframework.dataflow.qual.Pure;
 import org.checkerframework.dataflow.qual.SideEffectFree;
 import org.checkerframework.framework.qual.AnnotatedFor;
@@ -94,7 +95,7 @@ public Set<Entry<E>> entrySet() {
 
   @Pure
   @Override
-  public boolean equals(@CheckForNull Object object) {
+  public boolean equals(@CheckForNull @UnknownSignedness Object object) {
     return object == this || delegate().equals(object);
   }
 
diff --git a/guava/src/com/google/common/collect/ForwardingSet.java b/guava/src/com/google/common/collect/ForwardingSet.java
index fd9496276929..857e7fb98b91 100644
--- a/guava/src/com/google/common/collect/ForwardingSet.java
+++ b/guava/src/com/google/common/collect/ForwardingSet.java
@@ -23,6 +23,7 @@
 import java.util.Set;
 import javax.annotation.CheckForNull;
 import org.checkerframework.checker.nullness.qual.Nullable;
+import org.checkerframework.checker.signedness.qual.UnknownSignedness;
 import org.checkerframework.dataflow.qual.Pure;
 import org.checkerframework.framework.qual.AnnotatedFor;
 
@@ -63,7 +64,7 @@ protected ForwardingSet() {}
 
   @Pure
   @Override
-  public boolean equals(@CheckForNull Object object) {
+  public boolean equals(@CheckForNull @UnknownSignedness Object object) {
     return object == this || delegate().equals(object);
   }
 
diff --git a/guava/src/com/google/common/collect/ImmutableAsList.java b/guava/src/com/google/common/collect/ImmutableAsList.java
index c39747931796..19edf62415c7 100644
--- a/guava/src/com/google/common/collect/ImmutableAsList.java
+++ b/guava/src/com/google/common/collect/ImmutableAsList.java
@@ -23,6 +23,8 @@
 import java.io.Serializable;
 import javax.annotation.CheckForNull;
 
+import org.checkerframework.checker.signedness.qual.UnknownSignedness;
+
 /**
  * List returned by {@link ImmutableCollection#asList} that delegates {@code contains} checks to the
  * backing collection.
@@ -37,7 +39,7 @@ abstract class ImmutableAsList<E> extends ImmutableList<E> {
   abstract ImmutableCollection<E> delegateCollection();
 
   @Override
-  public boolean contains(@CheckForNull Object target) {
+  public boolean contains(@CheckForNull @UnknownSignedness Object target) {
     // The collection's contains() is at least as fast as ImmutableList's
     // and is often faster.
     return delegateCollection().contains(target);
diff --git a/guava/src/com/google/common/collect/ImmutableBiMap.java b/guava/src/com/google/common/collect/ImmutableBiMap.java
index 6bf472c586c2..64e5b77786c1 100644
--- a/guava/src/com/google/common/collect/ImmutableBiMap.java
+++ b/guava/src/com/google/common/collect/ImmutableBiMap.java
@@ -33,6 +33,7 @@
 import java.util.stream.Collectors;
 import javax.annotation.CheckForNull;
 import org.checkerframework.checker.nullness.qual.Nullable;
+import org.checkerframework.checker.signedness.qual.UnknownSignedness;
 import org.checkerframework.dataflow.qual.SideEffectFree;
 import org.checkerframework.framework.qual.AnnotatedFor;
 
@@ -643,10 +644,10 @@ Object writeReplace() {
   }
 
 @Override
-public boolean containsKey(@Nullable Object arg0) { return super.containsKey(arg0); }
+public boolean containsKey(@Nullable @UnknownSignedness Object arg0) { return super.containsKey(arg0); }
 
 @Override
-public boolean containsValue(@Nullable Object arg0) { return super.containsValue(arg0); }
+public boolean containsValue(@Nullable @UnknownSignedness Object arg0) { return super.containsValue(arg0); }
 
 @Override
 public boolean equals(@Nullable Object arg0) { return super.equals(arg0); }
diff --git a/guava/src/com/google/common/collect/ImmutableCollection.java b/guava/src/com/google/common/collect/ImmutableCollection.java
index 7261dca60387..ae6e5873a9c7 100644
--- a/guava/src/com/google/common/collect/ImmutableCollection.java
+++ b/guava/src/com/google/common/collect/ImmutableCollection.java
@@ -35,6 +35,9 @@
 import javax.annotation.CheckForNull;
 import org.checkerframework.checker.nullness.qual.NonNull;
 import org.checkerframework.checker.nullness.qual.Nullable;
+import org.checkerframework.checker.nullness.qual.PolyNull;
+import org.checkerframework.checker.signedness.qual.PolySigned;
+import org.checkerframework.checker.signedness.qual.UnknownSignedness;
 import org.checkerframework.dataflow.qual.Pure;
 import org.checkerframework.framework.qual.AnnotatedFor;
 
@@ -193,7 +196,7 @@ public Spliterator<E> spliterator() {
   private static final Object[] EMPTY_ARRAY = {};
 
   @Override
-  public final @Nullable Object[] toArray() {
+  public final @PolyNull @PolySigned Object[] toArray() {
     return toArray(EMPTY_ARRAY);
   }
 
@@ -211,8 +214,8 @@ public Spliterator<E> spliterator() {
    * require its own suppression, since it is also unsound. toArray(T[]) is just a mess from a
    * nullness perspective. The signature below at least has the virtue of being relatively simple.
    */
-  @SuppressWarnings("nullness")
-  public final <T extends @Nullable Object> T[] toArray(T[] other) {
+  @SuppressWarnings({"nullness:return", "nullness:assignment"})
+  public final <T extends @Nullable @UnknownSignedness Object> T[] toArray(T[] other) {
     checkNotNull(other);
     int size = size();
 
@@ -253,7 +256,7 @@ int internalArrayEnd() {
 
   @Pure
   @Override
-  public abstract boolean contains(@CheckForNull Object object);
+  public abstract boolean contains(@CheckForNull @UnknownSignedness Object object);
 
   /**
    * Guaranteed to throw an exception and leave the collection unmodified.
@@ -279,7 +282,7 @@ public final boolean add(E e) {
   @Deprecated
   @Override
   @DoNotCall("Always throws UnsupportedOperationException")
-  public final boolean remove(@CheckForNull Object object) {
+  public final boolean remove(@CheckForNull @UnknownSignedness Object object) {
     throw new UnsupportedOperationException();
   }
 
diff --git a/guava/src/com/google/common/collect/ImmutableList.java b/guava/src/com/google/common/collect/ImmutableList.java
index 58f15602dd67..7ec268d28276 100644
--- a/guava/src/com/google/common/collect/ImmutableList.java
+++ b/guava/src/com/google/common/collect/ImmutableList.java
@@ -48,6 +48,7 @@
 import javax.annotation.CheckForNull;
 import org.checkerframework.checker.nullness.qual.NonNull;
 import org.checkerframework.checker.nullness.qual.Nullable;
+import org.checkerframework.checker.signedness.qual.UnknownSignedness;
 import org.checkerframework.dataflow.qual.Pure;
 import org.checkerframework.framework.qual.AnnotatedFor;
 
@@ -436,18 +437,18 @@ public void forEach(Consumer<? super E> consumer) {
   }
 
   @Override
-  public int indexOf(@CheckForNull Object object) {
+  public int indexOf(@CheckForNull @UnknownSignedness Object object) {
     return (object == null) ? -1 : Lists.indexOfImpl(this, object);
   }
 
   @Pure
   @Override
-  public int lastIndexOf(@CheckForNull Object object) {
+  public int lastIndexOf(@CheckForNull @UnknownSignedness Object object) {
     return (object == null) ? -1 : Lists.lastIndexOfImpl(this, object);
   }
 
   @Override
-  public boolean contains(@CheckForNull Object object) {
+  public boolean contains(@CheckForNull @UnknownSignedness Object object) {
     return indexOf(object) >= 0;
   }
 
@@ -655,18 +656,18 @@ public ImmutableList<E> reverse() {
     }
 
     @Override
-    public boolean contains(@CheckForNull Object object) {
+    public boolean contains(@CheckForNull @UnknownSignedness Object object) {
       return forwardList.contains(object);
     }
 
     @Override
-    public int indexOf(@CheckForNull Object object) {
+    public int indexOf(@CheckForNull @UnknownSignedness Object object) {
       int index = forwardList.lastIndexOf(object);
       return (index >= 0) ? reverseIndex(index) : -1;
     }
 
     @Override
-    public int lastIndexOf(@CheckForNull Object object) {
+    public int lastIndexOf(@CheckForNull @UnknownSignedness Object object) {
       int index = forwardList.indexOf(object);
       return (index >= 0) ? reverseIndex(index) : -1;
     }
@@ -695,7 +696,7 @@ boolean isPartialView() {
   }
 
   @Override
-  public boolean equals(@CheckForNull Object obj) {
+  public boolean equals(@CheckForNull @UnknownSignedness Object obj) {
     return Lists.equalsImpl(this, obj);
   }
 
diff --git a/guava/src/com/google/common/collect/ImmutableMap.java b/guava/src/com/google/common/collect/ImmutableMap.java
index 6b192baa73dc..2664d9583017 100644
--- a/guava/src/com/google/common/collect/ImmutableMap.java
+++ b/guava/src/com/google/common/collect/ImmutableMap.java
@@ -54,6 +54,7 @@
 import org.checkerframework.checker.nullness.qual.MonotonicNonNull;
 import org.checkerframework.checker.nullness.qual.NonNull;
 import org.checkerframework.checker.nullness.qual.Nullable;
+import org.checkerframework.checker.signedness.qual.UnknownSignedness;
 import org.checkerframework.dataflow.qual.Pure;
 import org.checkerframework.dataflow.qual.SideEffectFree;
 import org.checkerframework.framework.qual.AnnotatedFor;
@@ -919,7 +920,7 @@ public final void replaceAll(BiFunction<? super K, ? super V, ? extends V> funct
   @Override
   @DoNotCall("Always throws UnsupportedOperationException")
   @CheckForNull
-  public final V remove(@CheckForNull Object o) {
+  public final V remove(@CheckForNull @UnknownSignedness Object o) {
     throw new UnsupportedOperationException();
   }
 
@@ -932,7 +933,7 @@ public final V remove(@CheckForNull Object o) {
   @Deprecated
   @Override
   @DoNotCall("Always throws UnsupportedOperationException")
-  public final boolean remove(@CheckForNull Object key, @CheckForNull Object value) {
+  public final boolean remove(@CheckForNull @UnknownSignedness Object key, @CheckForNull @UnknownSignedness Object value) {
     throw new UnsupportedOperationException();
   }
 
@@ -957,20 +958,20 @@ public boolean isEmpty() {
 
   @Pure
   @Override
-  public boolean containsKey(@CheckForNull Object key) {
+  public boolean containsKey(@CheckForNull @UnknownSignedness Object key) {
     return get(key) != null;
   }
 
   @Pure
   @Override
-  public boolean containsValue(@CheckForNull Object value) {
+  public boolean containsValue(@CheckForNull @UnknownSignedness Object value) {
     return values().contains(value);
   }
 
   // Overriding to mark it Nullable
   @Override
   @CheckForNull
-  public abstract V get(@CheckForNull Object key);
+  public abstract V get(@CheckForNull @UnknownSignedness Object key);
 
   /**
    * @since 21.0 (but only since 23.5 in the Android <a
@@ -979,7 +980,7 @@ public boolean containsValue(@CheckForNull Object value) {
    */
   @Override
   @CheckForNull
-  public final V getOrDefault(@CheckForNull Object key, @CheckForNull V defaultValue) {
+  public final V getOrDefault(@CheckForNull @UnknownSignedness Object key, @CheckForNull V defaultValue) {
     /*
      * Even though it's weird to pass a defaultValue that is null, some callers do so. Those who
      * pass a literal "null" should probably just use `get`, but I would expect other callers to
@@ -1122,13 +1123,13 @@ ImmutableSet<K> createKeySet() {
     }
 
     @Override
-    public boolean containsKey(@CheckForNull Object key) {
+    public boolean containsKey(@CheckForNull @UnknownSignedness Object key) {
       return ImmutableMap.this.containsKey(key);
     }
 
     @Override
     @CheckForNull
-    public ImmutableSet<V> get(@CheckForNull Object key) {
+    public ImmutableSet<V> get(@CheckForNull @UnknownSignedness Object key) {
       V outerValue = ImmutableMap.this.get(key);
       return (outerValue == null) ? null : ImmutableSet.of(outerValue);
     }
diff --git a/guava/src/com/google/common/collect/ImmutableMapEntrySet.java b/guava/src/com/google/common/collect/ImmutableMapEntrySet.java
index 6f5503af5c11..5eb3853e62ff 100644
--- a/guava/src/com/google/common/collect/ImmutableMapEntrySet.java
+++ b/guava/src/com/google/common/collect/ImmutableMapEntrySet.java
@@ -24,6 +24,7 @@
 import java.util.function.Consumer;
 import javax.annotation.CheckForNull;
 import org.checkerframework.checker.nullness.qual.Nullable;
+import org.checkerframework.checker.signedness.qual.UnknownSignedness;
 
 /**
  * {@code entrySet()} implementation for {@link ImmutableMap}.
@@ -89,7 +90,7 @@ public int size() {
   }
 
   @Override
-  public boolean contains(@CheckForNull Object object) {
+  public boolean contains(@CheckForNull @UnknownSignedness Object object) {
     if (object instanceof Entry) {
       Entry<?, ?> entry = (Entry<?, ?>) object;
       V value = map().get(entry.getKey());
diff --git a/guava/src/com/google/common/collect/ImmutableMultimap.java b/guava/src/com/google/common/collect/ImmutableMultimap.java
index cb79fd7ce8f0..b98dc2c9fbca 100644
--- a/guava/src/com/google/common/collect/ImmutableMultimap.java
+++ b/guava/src/com/google/common/collect/ImmutableMultimap.java
@@ -42,6 +42,7 @@
 import java.util.function.BiConsumer;
 import javax.annotation.CheckForNull;
 import org.checkerframework.checker.nullness.qual.Nullable;
+import org.checkerframework.checker.signedness.qual.UnknownSignedness;
 import org.checkerframework.dataflow.qual.Pure;
 import org.checkerframework.dataflow.qual.SideEffectFree;
 import org.checkerframework.framework.qual.AnnotatedFor;
@@ -580,7 +581,7 @@ public int size() {
 
     @Pure
     @Override
-    public boolean contains(@CheckForNull Object object) {
+    public boolean contains(@CheckForNull @UnknownSignedness Object object) {
       if (object instanceof Entry) {
         Entry<?, ?> entry = (Entry<?, ?>) object;
         return multimap.containsEntry(entry.getKey(), entry.getValue());
@@ -661,7 +662,7 @@ ImmutableMultiset<K> createKeys() {
   @WeakOuter
   class Keys extends ImmutableMultiset<K> {
     @Override
-    public boolean contains(@CheckForNull Object object) {
+    public boolean contains(@CheckForNull @UnknownSignedness Object object) {
       return containsKey(object);
     }
 
@@ -756,7 +757,7 @@ private static final class Values<K, V> extends ImmutableCollection<V> {
     }
 
     @Override
-    public boolean contains(@CheckForNull Object object) {
+    public boolean contains(@CheckForNull @UnknownSignedness Object object) {
       return multimap.containsValue(object);
     }
 
diff --git a/guava/src/com/google/common/collect/ImmutableMultiset.java b/guava/src/com/google/common/collect/ImmutableMultiset.java
index 6ba1a8f69392..34d3ba9be2c9 100644
--- a/guava/src/com/google/common/collect/ImmutableMultiset.java
+++ b/guava/src/com/google/common/collect/ImmutableMultiset.java
@@ -37,6 +37,7 @@
 import java.util.stream.Collector;
 import javax.annotation.CheckForNull;
 import org.checkerframework.checker.nullness.qual.Nullable;
+import org.checkerframework.checker.signedness.qual.UnknownSignedness;
 import org.checkerframework.dataflow.qual.Pure;
 import org.checkerframework.dataflow.qual.SideEffectFree;
 import org.checkerframework.framework.qual.AnnotatedFor;
@@ -268,7 +269,7 @@ public ImmutableList<E> asList() {
   }
 
   @Override
-  public boolean contains(@CheckForNull Object object) {
+  public boolean contains(@CheckForNull @UnknownSignedness Object object) {
     return count(object) > 0;
   }
 
@@ -340,7 +341,7 @@ int copyIntoArray(@Nullable Object[] dst, int offset) {
 
   @Pure
   @Override
-  public boolean equals(@CheckForNull Object object) {
+  public boolean equals(@CheckForNull @UnknownSignedness Object object) {
     return Multisets.equalsImpl(this, object);
   }
 
@@ -395,7 +396,7 @@ public int size() {
 
     @Pure
     @Override
-    public boolean contains(@CheckForNull Object o) {
+    public boolean contains(@CheckForNull @UnknownSignedness Object o) {
       if (o instanceof Entry) {
         Entry<?> entry = (Entry<?>) o;
         if (entry.getCount() <= 0) {
@@ -611,7 +612,7 @@ E get(int index) {
     }
 
     @Override
-    public boolean contains(@CheckForNull Object object) {
+    public boolean contains(@CheckForNull @UnknownSignedness Object object) {
       return delegate.contains(object);
     }
 
diff --git a/guava/src/com/google/common/collect/ImmutableSet.java b/guava/src/com/google/common/collect/ImmutableSet.java
index 964a873e3a4d..359c92a34acb 100644
--- a/guava/src/com/google/common/collect/ImmutableSet.java
+++ b/guava/src/com/google/common/collect/ImmutableSet.java
@@ -44,6 +44,7 @@
 import javax.annotation.CheckForNull;
 import org.checkerframework.checker.nullness.qual.NonNull;
 import org.checkerframework.checker.nullness.qual.Nullable;
+import org.checkerframework.checker.signedness.qual.UnknownSignedness;
 import org.checkerframework.dataflow.qual.Pure;
 import org.checkerframework.framework.qual.AnnotatedFor;
 
@@ -318,7 +319,7 @@ boolean isHashCodeFast() {
 
   @Pure
   @Override
-  public boolean equals(@CheckForNull Object object) {
+  public boolean equals(@CheckForNull @UnknownSignedness Object object) {
     if (object == this) {
       return true;
     }
diff --git a/guava/src/com/google/common/collect/ImmutableSetMultimap.java b/guava/src/com/google/common/collect/ImmutableSetMultimap.java
index e76767dc0b1f..af1e91ebf6c3 100644
--- a/guava/src/com/google/common/collect/ImmutableSetMultimap.java
+++ b/guava/src/com/google/common/collect/ImmutableSetMultimap.java
@@ -41,6 +41,7 @@
 import java.util.stream.Stream;
 import javax.annotation.CheckForNull;
 import org.checkerframework.checker.nullness.qual.Nullable;
+import org.checkerframework.checker.signedness.qual.UnknownSignedness;
 import org.checkerframework.dataflow.qual.SideEffectFree;
 import org.checkerframework.framework.qual.AnnotatedFor;
 
@@ -536,7 +537,7 @@ private static final class EntrySet<K, V> extends ImmutableSet<Entry<K, V>> {
     }
 
     @Override
-    public boolean contains(@CheckForNull Object object) {
+    public boolean contains(@CheckForNull @UnknownSignedness Object object) {
       if (object instanceof Entry) {
         Entry<?, ?> entry = (Entry<?, ?>) object;
         return multimap.containsEntry(entry.getKey(), entry.getValue());
diff --git a/guava/src/com/google/common/collect/LinkedHashMultiset.java b/guava/src/com/google/common/collect/LinkedHashMultiset.java
index d4a046816ab4..17f020783dfa 100644
--- a/guava/src/com/google/common/collect/LinkedHashMultiset.java
+++ b/guava/src/com/google/common/collect/LinkedHashMultiset.java
@@ -24,6 +24,7 @@
 import java.util.Collection;
 import java.util.LinkedHashMap;
 import org.checkerframework.checker.nullness.qual.Nullable;
+import org.checkerframework.checker.signedness.qual.UnknownSignedness;
 import org.checkerframework.dataflow.qual.Pure;
 import org.checkerframework.framework.qual.AnnotatedFor;
 
@@ -108,7 +109,7 @@ private void readObject(ObjectInputStream stream) throws IOException, ClassNotFo
 
   @Pure
   @Override
-  public boolean contains(@Nullable Object arg0) { return super.contains(arg0); }
+  public boolean contains(@Nullable @UnknownSignedness Object arg0) { return super.contains(arg0); }
 
   @Override
   public int count(@Nullable Object arg0) { return super.count(arg0); }
diff --git a/guava/src/com/google/common/collect/Lists.java b/guava/src/com/google/common/collect/Lists.java
index 79a2100b0258..9a704e003ac1 100644
--- a/guava/src/com/google/common/collect/Lists.java
+++ b/guava/src/com/google/common/collect/Lists.java
@@ -51,6 +51,7 @@
 import java.util.function.Predicate;
 import javax.annotation.CheckForNull;
 import org.checkerframework.checker.nullness.qual.Nullable;
+import org.checkerframework.checker.signedness.qual.UnknownSignedness;
 import org.checkerframework.dataflow.qual.Pure;
 import org.checkerframework.framework.qual.AnnotatedFor;
 
@@ -753,12 +754,12 @@ private static final class StringAsImmutableList extends ImmutableList<Character
     }
 
     @Override
-    public int indexOf(@CheckForNull Object object) {
+    public int indexOf(@CheckForNull @UnknownSignedness Object object) {
       return (object instanceof Character) ? string.indexOf((Character) object) : -1;
     }
 
     @Override
-    public int lastIndexOf(@CheckForNull Object object) {
+    public int lastIndexOf(@CheckForNull @UnknownSignedness Object object) {
       return (object instanceof Character) ? string.lastIndexOf((Character) object) : -1;
     }
 
@@ -1166,7 +1167,7 @@ public E set(int index, @ParametricNullness E element) {
     }
 
     @Override
-    public boolean contains(@CheckForNull Object o) {
+    public boolean contains(@CheckForNull @UnknownSignedness Object o) {
       return backingList.contains(o);
     }
 
diff --git a/guava/src/com/google/common/collect/Maps.java b/guava/src/com/google/common/collect/Maps.java
index 90785d0cba4c..a8b1eaf72b62 100644
--- a/guava/src/com/google/common/collect/Maps.java
+++ b/guava/src/com/google/common/collect/Maps.java
@@ -72,6 +72,9 @@
 import java.util.stream.Collector;
 import javax.annotation.CheckForNull;
 import org.checkerframework.checker.nullness.qual.Nullable;
+import org.checkerframework.checker.nullness.qual.PolyNull;
+import org.checkerframework.checker.signedness.qual.PolySigned;
+import org.checkerframework.checker.signedness.qual.UnknownSignedness;
 import org.checkerframework.dataflow.qual.Pure;
 import org.checkerframework.dataflow.qual.SideEffectFree;
 import org.checkerframework.framework.qual.AnnotatedFor;
@@ -939,19 +942,19 @@ public int size() {
     }
 
     @Override
-    public boolean containsKey(@CheckForNull Object key) {
+    public boolean containsKey(@CheckForNull @UnknownSignedness Object key) {
       return backingSet().contains(key);
     }
 
     @Override
     @CheckForNull
-    public V get(@CheckForNull Object key) {
+    public V get(@CheckForNull @UnknownSignedness Object key) {
       return getOrDefault(key, null);
     }
 
     @Override
     @CheckForNull
-    public V getOrDefault(@CheckForNull Object key, @CheckForNull V defaultValue) {
+    public V getOrDefault(@CheckForNull @UnknownSignedness Object key, @CheckForNull V defaultValue) {
       if (Collections2.safeContains(backingSet(), key)) {
         @SuppressWarnings("unchecked") // unsafe, but Javadoc warns about it
         K k = (K) key;
@@ -963,7 +966,7 @@ public V getOrDefault(@CheckForNull Object key, @CheckForNull V defaultValue) {
 
     @Override
     @CheckForNull
-    public V remove(@CheckForNull Object key) {
+    public V remove(@CheckForNull @UnknownSignedness Object key) {
       if (backingSet().remove(key)) {
         @SuppressWarnings("unchecked") // unsafe, but Javadoc warns about it
         K k = (K) key;
@@ -1108,13 +1111,13 @@ public Comparator<? super K> comparator() {
 
     @Override
     @CheckForNull
-    public V get(@CheckForNull Object key) {
+    public V get(@CheckForNull @UnknownSignedness Object key) {
       return getOrDefault(key, null);
     }
 
     @Override
     @CheckForNull
-    public V getOrDefault(@CheckForNull Object key, @CheckForNull V defaultValue) {
+    public V getOrDefault(@CheckForNull @UnknownSignedness Object key, @CheckForNull V defaultValue) {
       if (Collections2.safeContains(set, key)) {
         @SuppressWarnings("unchecked") // unsafe, but Javadoc warns about it
         K k = (K) key;
@@ -1554,7 +1557,7 @@ public Iterator<Entry<K, V>> iterator() {
     // See java.util.Collections.UnmodifiableEntrySet for details on attacks.
 
     @Override
-    public Object[] toArray() {
+    public @PolySigned Object[] toArray() {
       /*
        * standardToArray returns `@Nullable Object[]` rather than `Object[]` but only because it can
        * be used with collections that may contain null. This collection never contains nulls, so we
@@ -1567,13 +1570,13 @@ public Object[] toArray() {
 
     @Override
     @SuppressWarnings("nullness") // b/192354773 in our checker affects toArray declarations
-    public <T extends @Nullable Object> T[] toArray(T[] array) {
+    public <T extends @Nullable @UnknownSignedness Object> T[] toArray(T[] array) {
       return standardToArray(array);
     }
 
   @Pure
   @Override
-  public boolean contains(@Nullable Object arg0) { return super.contains(arg0); }
+  public boolean contains(@Nullable @UnknownSignedness Object arg0) { return super.contains(arg0); }
 
   @Pure
   @Override
@@ -1591,7 +1594,7 @@ static class UnmodifiableEntrySet<K extends @Nullable Object, V extends @Nullabl
 
     @Pure
     @Override
-    public boolean equals(@CheckForNull Object object) {
+    public boolean equals(@CheckForNull @UnknownSignedness Object object) {
       return Sets.equalsImpl(this, object);
     }
 
@@ -1749,7 +1752,7 @@ public V putIfAbsent(K key, V value) {
     }
 
     @Override
-    public boolean remove(@Nullable Object key, @Nullable Object value) {
+    public boolean remove(@Nullable @UnknownSignedness Object key, @Nullable @UnknownSignedness Object value) {
       throw new UnsupportedOperationException();
     }
 
@@ -2219,13 +2222,13 @@ public int size() {
     }
 
     @Override
-    public boolean containsKey(@CheckForNull Object key) {
+    public boolean containsKey(@CheckForNull @UnknownSignedness Object key) {
       return fromMap.containsKey(key);
     }
 
     @Override
     @CheckForNull
-    public V2 get(@CheckForNull Object key) {
+    public V2 get(@CheckForNull @UnknownSignedness Object key) {
       return getOrDefault(key, null);
     }
 
@@ -2233,7 +2236,7 @@ public V2 get(@CheckForNull Object key) {
     @SuppressWarnings("unchecked")
     @Override
     @CheckForNull
-    public V2 getOrDefault(@CheckForNull Object key, @CheckForNull V2 defaultValue) {
+    public V2 getOrDefault(@CheckForNull @UnknownSignedness Object key, @CheckForNull V2 defaultValue) {
       V1 value = fromMap.get(key);
       if (value != null || fromMap.containsKey(key)) {
         // The cast is safe because of the containsKey check.
@@ -2246,7 +2249,7 @@ public V2 getOrDefault(@CheckForNull Object key, @CheckForNull V2 defaultValue)
     @SuppressWarnings("unchecked")
     @Override
     @CheckForNull
-    public V2 remove(@CheckForNull Object key) {
+    public V2 remove(@CheckForNull @UnknownSignedness Object key) {
       return fromMap.containsKey(key)
           // The cast is safe because of the containsKey check.
           ? transformer.transformEntry((K) key, uncheckedCastNullableTToT(fromMap.remove(key)))
@@ -2963,13 +2966,13 @@ public void putAll(Map<? extends K, ? extends V> map) {
 
     @Pure
     @Override
-    public boolean containsKey(@CheckForNull Object key) {
+    public boolean containsKey(@CheckForNull @UnknownSignedness Object key) {
       return unfiltered.containsKey(key) && apply(key, unfiltered.get(key));
     }
 
     @Override
     @CheckForNull
-    public V get(@CheckForNull Object key) {
+    public V get(@CheckForNull @UnknownSignedness Object key) {
       V value = unfiltered.get(key);
       return ((value != null) && apply(key, value)) ? value : null;
     }
@@ -2982,7 +2985,7 @@ public boolean isEmpty() {
 
     @Override
     @CheckForNull
-    public V remove(@CheckForNull Object key) {
+    public V remove(@CheckForNull @UnknownSignedness Object key) {
       return containsKey(key) ? unfiltered.remove(key) : null;
     }
 
@@ -3006,7 +3009,7 @@ private static final class FilteredMapValues<
     }
 
     @Override
-    public boolean remove(@CheckForNull Object o) {
+    public boolean remove(@CheckForNull @UnknownSignedness Object o) {
       Iterator<Entry<K, V>> entryItr = unfiltered.entrySet().iterator();
       while (entryItr.hasNext()) {
         Entry<K, V> entry = entryItr.next();
@@ -3047,14 +3050,14 @@ public boolean retainAll(Collection<?> collection) {
     }
 
     @Override
-    public @Nullable Object[] toArray() {
+    public @Nullable @PolySigned Object[] toArray() {
       // creating an ArrayList so filtering happens once
       return Lists.newArrayList(iterator()).toArray();
     }
 
     @Override
     @SuppressWarnings("nullness") // b/192354773 in our checker affects toArray declarations
-    public <T extends @Nullable Object> T[] toArray(T[] array) {
+    public <T extends @Nullable @UnknownSignedness Object> T[] toArray(T[] array) {
       return Lists.newArrayList(iterator()).toArray(array);
     }
   }
@@ -3086,7 +3089,7 @@ Set<K> createKeySet() {
     @Pure
     @Override
     @SuppressWarnings("unchecked")
-    public boolean containsKey(@CheckForNull Object key) {
+    public boolean containsKey(@CheckForNull @UnknownSignedness Object key) {
       return unfiltered.containsKey(key) && keyPredicate.apply((K) key);
     }
   }
@@ -3179,7 +3182,7 @@ class KeySet extends Maps.KeySet<K, V> {
       }
 
       @Override
-      public boolean remove(@CheckForNull Object o) {
+      public boolean remove(@CheckForNull @UnknownSignedness Object o) {
         if (containsKey(o)) {
           unfiltered.remove(o);
           return true;
@@ -3198,20 +3201,20 @@ public boolean retainAll(Collection<?> collection) {
       }
 
       @Override
-      public @Nullable Object[] toArray() {
+      public @PolyNull @PolySigned Object[] toArray() {
         // creating an ArrayList so filtering happens once
         return Lists.newArrayList(iterator()).toArray();
       }
 
       @Override
       @SuppressWarnings("nullness") // b/192354773 in our checker affects toArray declarations
-      public <T extends @Nullable Object> T[] toArray(T[] array) {
+      public <T extends @Nullable @UnknownSignedness Object> T[] toArray(T[] array) {
         return Lists.newArrayList(iterator()).toArray(array);
       }
 
     @Pure
     @Override
-    public boolean contains(@Nullable Object arg0) { return super.contains(arg0); }
+    public boolean contains(@Nullable @UnknownSignedness Object arg0) { return super.contains(arg0); }
     }
   }
 
@@ -3388,12 +3391,12 @@ public boolean isEmpty() {
 
     @Override
     @CheckForNull
-    public V get(@CheckForNull Object key) {
+    public V get(@CheckForNull @UnknownSignedness Object key) {
       return filteredDelegate.get(key);
     }
 
     @Override
-    public boolean containsKey(@CheckForNull Object key) {
+    public boolean containsKey(@CheckForNull @UnknownSignedness Object key) {
       return filteredDelegate.containsKey(key);
     }
 
@@ -3405,7 +3408,7 @@ public V put(@ParametricNullness K key, @ParametricNullness V value) {
 
     @Override
     @CheckForNull
-    public V remove(@CheckForNull Object key) {
+    public V remove(@CheckForNull @UnknownSignedness Object key) {
       return filteredDelegate.remove(key);
     }
 
@@ -3662,7 +3665,7 @@ public V putIfAbsent(K key, V value) {
     }
 
     @Override
-    public boolean remove(@Nullable Object key, @Nullable Object value) {
+    public boolean remove(@Nullable @UnknownSignedness Object key, @Nullable @UnknownSignedness Object value) {
       throw new UnsupportedOperationException();
     }
 
@@ -4071,12 +4074,12 @@ public boolean isEmpty() {
     }
 
     @Override
-    public boolean contains(@CheckForNull Object o) {
+    public boolean contains(@CheckForNull @UnknownSignedness Object o) {
       return map().containsKey(o);
     }
 
     @Override
-    public boolean remove(@CheckForNull Object o) {
+    public boolean remove(@CheckForNull @UnknownSignedness Object o) {
       if (contains(o)) {
         map().remove(o);
         return true;
@@ -4263,7 +4266,7 @@ public void forEach(Consumer<? super V> action) {
     }
 
     @Override
-    public boolean remove(@CheckForNull Object o) {
+    public boolean remove(@CheckForNull @UnknownSignedness Object o) {
       try {
         return super.remove(o);
       } catch (UnsupportedOperationException e) {
@@ -4318,7 +4321,7 @@ public boolean isEmpty() {
     }
 
     @Override
-    public boolean contains(@CheckForNull Object o) {
+    public boolean contains(@CheckForNull @UnknownSignedness Object o) {
       return map().containsValue(o);
     }
 
@@ -4343,7 +4346,7 @@ public void clear() {
     }
 
     @Override
-    public boolean contains(@CheckForNull Object o) {
+    public boolean contains(@CheckForNull @UnknownSignedness Object o) {
       if (o instanceof Entry) {
         Entry<?, ?> entry = (Entry<?, ?>) o;
         Object key = entry.getKey();
@@ -4359,7 +4362,7 @@ public boolean isEmpty() {
     }
 
     @Override
-    public boolean remove(@CheckForNull Object o) {
+    public boolean remove(@CheckForNull @UnknownSignedness Object o) {
       /*
        * `o instanceof Entry` is guaranteed by `contains`, but we check it here to satisfy our
        * nullness checker.
diff --git a/guava/src/com/google/common/collect/Multimaps.java b/guava/src/com/google/common/collect/Multimaps.java
index 88c1aff76042..91d43b0db445 100644
--- a/guava/src/com/google/common/collect/Multimaps.java
+++ b/guava/src/com/google/common/collect/Multimaps.java
@@ -58,6 +58,7 @@
 import java.util.stream.Stream;
 import javax.annotation.CheckForNull;
 import org.checkerframework.checker.nullness.qual.Nullable;
+import org.checkerframework.checker.signedness.qual.UnknownSignedness;
 import org.checkerframework.dataflow.qual.Pure;
 import org.checkerframework.dataflow.qual.SideEffectFree;
 import org.checkerframework.framework.qual.AnnotatedFor;
@@ -1788,7 +1789,7 @@ public int size() {
     }
 
     @Override
-    public boolean contains(@CheckForNull Object element) {
+    public boolean contains(@CheckForNull @UnknownSignedness Object element) {
       return multimap.containsKey(element);
     }
 
@@ -1856,7 +1857,7 @@ public int size() {
     }
 
     @Override
-    public boolean contains(@CheckForNull Object o) {
+    public boolean contains(@CheckForNull @UnknownSignedness Object o) {
       if (o instanceof Map.Entry) {
         Map.Entry<?, ?> entry = (Map.Entry<?, ?>) o;
         return multimap().containsEntry(entry.getKey(), entry.getValue());
@@ -1865,7 +1866,7 @@ public boolean contains(@CheckForNull Object o) {
     }
 
     @Override
-    public boolean remove(@CheckForNull Object o) {
+    public boolean remove(@CheckForNull @UnknownSignedness Object o) {
       if (o instanceof Map.Entry) {
         Map.Entry<?, ?> entry = (Map.Entry<?, ?>) o;
         return multimap().remove(entry.getKey(), entry.getValue());
@@ -1922,7 +1923,7 @@ public Collection<V> apply(@ParametricNullness K key) {
       }
 
       @Override
-      public boolean remove(@CheckForNull Object o) {
+      public boolean remove(@CheckForNull @UnknownSignedness Object o) {
         if (!contains(o)) {
           return false;
         }
@@ -1936,13 +1937,13 @@ public boolean remove(@CheckForNull Object o) {
     @SuppressWarnings("unchecked")
     @Override
     @CheckForNull
-    public Collection<V> get(@CheckForNull Object key) {
+    public Collection<V> get(@CheckForNull @UnknownSignedness Object key) {
       return containsKey(key) ? multimap.get((K) key) : null;
     }
 
     @Override
     @CheckForNull
-    public Collection<V> remove(@CheckForNull Object key) {
+    public Collection<V> remove(@CheckForNull @UnknownSignedness Object key) {
       return containsKey(key) ? multimap.removeAll(key) : null;
     }
 
@@ -1957,7 +1958,7 @@ public boolean isEmpty() {
     }
 
     @Override
-    public boolean containsKey(@CheckForNull Object key) {
+    public boolean containsKey(@CheckForNull @UnknownSignedness Object key) {
       return multimap.containsKey(key);
     }
 
diff --git a/guava/src/com/google/common/collect/Multisets.java b/guava/src/com/google/common/collect/Multisets.java
index afb5bf67ba47..2fbcd54abafe 100644
--- a/guava/src/com/google/common/collect/Multisets.java
+++ b/guava/src/com/google/common/collect/Multisets.java
@@ -46,6 +46,7 @@
 import java.util.stream.Collector;
 import javax.annotation.CheckForNull;
 import org.checkerframework.checker.nullness.qual.Nullable;
+import org.checkerframework.checker.signedness.qual.UnknownSignedness;
 import org.checkerframework.dataflow.qual.Pure;
 import org.checkerframework.dataflow.qual.SideEffectFree;
 import org.checkerframework.framework.qual.AnnotatedFor;
@@ -187,7 +188,7 @@ public boolean addAll(Collection<? extends E> elementsToAdd) {
     }
 
     @Override
-    public boolean remove(@CheckForNull Object element) {
+    public boolean remove(@CheckForNull @UnknownSignedness Object element) {
       throw new UnsupportedOperationException();
     }
 
@@ -425,7 +426,7 @@ static int inferDistinctElements(Iterable<?> elements) {
 
     return new ViewMultiset<E>() {
       @Override
-      public boolean contains(@CheckForNull Object element) {
+      public boolean contains(@CheckForNull @UnknownSignedness Object element) {
         return multiset1.contains(element) || multiset2.contains(element);
       }
 
@@ -556,7 +557,7 @@ protected Entry<E> computeNext() {
     // TODO(lowasser): consider making the entries live views
     return new ViewMultiset<E>() {
       @Override
-      public boolean contains(@CheckForNull Object element) {
+      public boolean contains(@CheckForNull @UnknownSignedness Object element) {
         return multiset1.contains(element) || multiset2.contains(element);
       }
 
@@ -1004,7 +1005,7 @@ public void clear() {
     }
 
     @Override
-    public boolean contains(@CheckForNull Object o) {
+    public boolean contains(@CheckForNull @UnknownSignedness Object o) {
       return multiset().contains(o);
     }
 
@@ -1022,7 +1023,7 @@ public boolean isEmpty() {
     public abstract Iterator<E> iterator();
 
     @Override
-    public boolean remove(@CheckForNull Object o) {
+    public boolean remove(@CheckForNull @UnknownSignedness Object o) {
       return multiset().remove(o, Integer.MAX_VALUE) > 0;
     }
 
@@ -1037,7 +1038,7 @@ abstract static class EntrySet<E extends @Nullable Object>
     abstract Multiset<E> multiset();
 
     @Override
-    public boolean contains(@CheckForNull Object o) {
+    public boolean contains(@CheckForNull @UnknownSignedness Object o) {
       if (o instanceof Entry) {
         /*
          * The GWT compiler wrongly issues a warning here.
@@ -1056,7 +1057,7 @@ public boolean contains(@CheckForNull Object o) {
     // GWT compiler warning; see contains().
     @SuppressWarnings("cast")
     @Override
-    public boolean remove(@CheckForNull Object object) {
+    public boolean remove(@CheckForNull @UnknownSignedness Object object) {
       if (object instanceof Multiset.Entry) {
         Entry<?> entry = (Entry<?>) object;
         Object element = entry.getElement();
diff --git a/guava/src/com/google/common/collect/RegularImmutableBiMap.java b/guava/src/com/google/common/collect/RegularImmutableBiMap.java
index ed7c4fd1e5b4..f4928f3af2d5 100644
--- a/guava/src/com/google/common/collect/RegularImmutableBiMap.java
+++ b/guava/src/com/google/common/collect/RegularImmutableBiMap.java
@@ -35,6 +35,7 @@
 import java.util.function.Consumer;
 import javax.annotation.CheckForNull;
 import org.checkerframework.checker.nullness.qual.Nullable;
+import org.checkerframework.checker.signedness.qual.UnknownSignedness;
 import org.checkerframework.framework.qual.AnnotatedFor;
 
 /**
@@ -145,7 +146,7 @@ private static void checkNoConflictInValueBucket(
 
   @Override
   @CheckForNull
-  public V get(@CheckForNull Object key) {
+  public V get(@CheckForNull @UnknownSignedness Object key) {
     return RegularImmutableMap.get(key, keyTable, mask);
   }
 
@@ -220,7 +221,7 @@ public void forEach(BiConsumer<? super V, ? super K> action) {
 
     @Override
     @CheckForNull
-    public K get(@CheckForNull Object value) {
+    public K get(@CheckForNull @UnknownSignedness Object value) {
       if (value == null || valueTable == null) {
         return null;
       }
diff --git a/guava/src/com/google/common/collect/RegularImmutableList.java b/guava/src/com/google/common/collect/RegularImmutableList.java
index 9d4a5ba48ae1..e1dc4a467306 100644
--- a/guava/src/com/google/common/collect/RegularImmutableList.java
+++ b/guava/src/com/google/common/collect/RegularImmutableList.java
@@ -21,6 +21,7 @@
 import java.util.Spliterator;
 import java.util.Spliterators;
 import org.checkerframework.checker.nullness.qual.Nullable;
+import org.checkerframework.checker.signedness.qual.UnknownSignedness;
 import org.checkerframework.dataflow.qual.Pure;
 import org.checkerframework.dataflow.qual.SideEffectFree;
 import org.checkerframework.framework.qual.AnnotatedFor;
@@ -98,17 +99,17 @@ public Spliterator<E> spliterator() {
   // TODO(lowasser): benchmark optimizations for equals() and see if they're worthwhile
 
 @Override
-public boolean contains(@Nullable Object arg0) { return super.contains(arg0); }
+public boolean contains(@Nullable @UnknownSignedness Object arg0) { return super.contains(arg0); }
 
 @Pure
 @Override
-public boolean equals(@Nullable Object arg0) { return super.equals(arg0); }
+public boolean equals(@Nullable @UnknownSignedness Object arg0) { return super.equals(arg0); }
 
 @Override
-public int indexOf(@Nullable Object arg0) { return super.indexOf(arg0); }
+public int indexOf(@Nullable @UnknownSignedness Object arg0) { return super.indexOf(arg0); }
 
 @Override
-public int lastIndexOf(@Nullable Object arg0) { return super.lastIndexOf(arg0); }
+public int lastIndexOf(@Nullable @UnknownSignedness Object arg0) { return super.lastIndexOf(arg0); }
 
 @SideEffectFree
 @Override
diff --git a/guava/src/com/google/common/collect/RegularImmutableMap.java b/guava/src/com/google/common/collect/RegularImmutableMap.java
index ccbf7c32ed44..22e92b314f1f 100644
--- a/guava/src/com/google/common/collect/RegularImmutableMap.java
+++ b/guava/src/com/google/common/collect/RegularImmutableMap.java
@@ -33,6 +33,7 @@
 import java.util.function.BiConsumer;
 import javax.annotation.CheckForNull;
 import org.checkerframework.checker.nullness.qual.Nullable;
+import org.checkerframework.checker.signedness.qual.UnknownSignedness;
 import org.checkerframework.dataflow.qual.Pure;
 import org.checkerframework.dataflow.qual.SideEffectFree;
 import org.checkerframework.framework.qual.AnnotatedFor;
@@ -259,7 +260,7 @@ static class BucketOverflowException extends Exception {}
 
   @Override
   @CheckForNull
-  public V get(@CheckForNull Object key) {
+  public V get(@CheckForNull @UnknownSignedness Object key) {
     return get(key, table, mask);
   }
 
@@ -333,7 +334,7 @@ K get(int index) {
     }
 
     @Override
-    public boolean contains(@CheckForNull Object object) {
+    public boolean contains(@CheckForNull @UnknownSignedness Object object) {
       return map.containsKey(object);
     }
 
@@ -417,7 +418,7 @@ Object readResolve() {
 
   @Pure
   @Override
-  public boolean containsValue(@Nullable Object arg0) {
+  public boolean containsValue(@Nullable @UnknownSignedness Object arg0) {
     return super.containsValue(arg0);
   }
 
diff --git a/guava/src/com/google/common/collect/RegularImmutableSortedSet.java b/guava/src/com/google/common/collect/RegularImmutableSortedSet.java
index 4872f5faddb8..fce26bcc1d5c 100644
--- a/guava/src/com/google/common/collect/RegularImmutableSortedSet.java
+++ b/guava/src/com/google/common/collect/RegularImmutableSortedSet.java
@@ -30,6 +30,7 @@
 import java.util.function.Consumer;
 import javax.annotation.CheckForNull;
 import org.checkerframework.checker.nullness.qual.Nullable;
+import org.checkerframework.checker.signedness.qual.UnknownSignedness;
 import org.checkerframework.dataflow.qual.Pure;
 import org.checkerframework.dataflow.qual.SideEffectFree;
 import org.checkerframework.framework.qual.AnnotatedFor;
@@ -101,7 +102,7 @@ public int size() {
 
   @Pure
   @Override
-  public boolean contains(@CheckForNull Object o) {
+  public boolean contains(@CheckForNull @UnknownSignedness Object o) {
     try {
       return o != null && unsafeBinarySearch(o) >= 0;
     } catch (ClassCastException e) {
@@ -178,7 +179,7 @@ int copyIntoArray(@Nullable Object[] dst, int offset) {
 
   @Pure
   @Override
-  public boolean equals(@CheckForNull Object object) {
+  public boolean equals(@CheckForNull @UnknownSignedness Object object) {
     if (object == this) {
       return true;
     }
diff --git a/guava/src/com/google/common/collect/RegularImmutableTable.java b/guava/src/com/google/common/collect/RegularImmutableTable.java
index 337f123b698d..b7ec63f04596 100644
--- a/guava/src/com/google/common/collect/RegularImmutableTable.java
+++ b/guava/src/com/google/common/collect/RegularImmutableTable.java
@@ -26,6 +26,8 @@
 import java.util.Set;
 import javax.annotation.CheckForNull;
 
+import org.checkerframework.checker.signedness.qual.UnknownSignedness;
+
 /**
  * An implementation of {@link ImmutableTable} holding an arbitrary number of cells.
  *
@@ -56,7 +58,7 @@ Cell<R, C, V> get(int index) {
     }
 
     @Override
-    public boolean contains(@CheckForNull Object object) {
+    public boolean contains(@CheckForNull @UnknownSignedness Object object) {
       if (object instanceof Cell) {
         Cell<?, ?, ?> cell = (Cell<?, ?, ?>) object;
         Object value = RegularImmutableTable.this.get(cell.getRowKey(), cell.getColumnKey());
diff --git a/guava/src/com/google/common/collect/Sets.java b/guava/src/com/google/common/collect/Sets.java
index 9ea921ca1705..c99290590c14 100644
--- a/guava/src/com/google/common/collect/Sets.java
+++ b/guava/src/com/google/common/collect/Sets.java
@@ -54,6 +54,9 @@
 import java.util.stream.Stream;
 import javax.annotation.CheckForNull;
 import org.checkerframework.checker.nullness.qual.Nullable;
+import org.checkerframework.checker.nullness.qual.PolyNull;
+import org.checkerframework.checker.signedness.qual.PolySigned;
+import org.checkerframework.checker.signedness.qual.UnknownSignedness;
 import org.checkerframework.dataflow.qual.Pure;
 import org.checkerframework.framework.qual.AnnotatedFor;
 
@@ -613,7 +616,7 @@ public final boolean add(@ParametricNullness E e) {
     @Deprecated
     @Override
     @DoNotCall("Always throws UnsupportedOperationException")
-    public final boolean remove(@CheckForNull Object object) {
+    public final boolean remove(@CheckForNull @UnknownSignedness Object object) {
       throw new UnsupportedOperationException();
     }
 
@@ -763,7 +766,7 @@ public Stream<E> parallelStream() {
       }
 
       @Override
-      public boolean contains(@CheckForNull Object object) {
+      public boolean contains(@CheckForNull @UnknownSignedness Object object) {
         return set1.contains(object) || set2.contains(object);
       }
 
@@ -861,7 +864,7 @@ public boolean isEmpty() {
       }
 
       @Override
-      public boolean contains(@CheckForNull Object object) {
+      public boolean contains(@CheckForNull @UnknownSignedness Object object) {
         return set1.contains(object) && set2.contains(object);
       }
 
@@ -934,7 +937,7 @@ public boolean isEmpty() {
       }
 
       @Override
-      public boolean contains(@CheckForNull Object element) {
+      public boolean contains(@CheckForNull @UnknownSignedness Object element) {
         return set1.contains(element) && !set2.contains(element);
       }
     };
@@ -1004,7 +1007,7 @@ public boolean isEmpty() {
       }
 
       @Override
-      public boolean contains(@CheckForNull Object element) {
+      public boolean contains(@CheckForNull @UnknownSignedness Object element) {
         return set1.contains(element) ^ set2.contains(element);
       }
     };
@@ -1136,7 +1139,7 @@ private static class FilteredSet<E extends @Nullable Object> extends FilteredCol
     }
 
     @Override
-    public boolean equals(@CheckForNull Object object) {
+    public boolean equals(@CheckForNull @UnknownSignedness Object object) {
       return equalsImpl(this, object);
     }
 
@@ -1440,7 +1443,7 @@ protected Collection<List<E>> delegate() {
     }
 
     @Override
-    public boolean contains(@CheckForNull Object object) {
+    public boolean contains(@CheckForNull @UnknownSignedness Object object) {
       if (!(object instanceof List)) {
         return false;
       }
@@ -1459,7 +1462,7 @@ public boolean contains(@CheckForNull Object object) {
     }
 
     @Override
-    public boolean equals(@CheckForNull Object object) {
+    public boolean equals(@CheckForNull @UnknownSignedness Object object) {
       // Warning: this is broken if size() == 0, so it is critical that we
       // substitute an empty ImmutableSet to the user in place of this
       if (object instanceof CartesianSet) {
@@ -1559,7 +1562,7 @@ public int size() {
     }
 
     @Override
-    public boolean contains(@CheckForNull Object o) {
+    public boolean contains(@CheckForNull @UnknownSignedness Object o) {
       Integer index = inputSet.get(o);
       return index != null && (mask & (1 << index)) != 0;
     }
@@ -1595,7 +1598,7 @@ protected Set<E> get(final int setBits) {
     }
 
     @Override
-    public boolean contains(@CheckForNull Object obj) {
+    public boolean contains(@CheckForNull @UnknownSignedness Object obj) {
       if (obj instanceof Set) {
         Set<?> set = (Set<?>) obj;
         return inputSet.keySet().containsAll(set);
@@ -1604,7 +1607,7 @@ public boolean contains(@CheckForNull Object obj) {
     }
 
     @Override
-    public boolean equals(@CheckForNull Object obj) {
+    public boolean equals(@CheckForNull @UnknownSignedness Object obj) {
       if (obj instanceof PowerSet) {
         PowerSet<?> that = (PowerSet<?>) obj;
         return inputSet.keySet().equals(that.inputSet.keySet());
@@ -1664,7 +1667,7 @@ public static <E> Set<Set<E>> combinations(Set<E> set, final int size) {
     }
     return new AbstractSet<Set<E>>() {
       @Override
-      public boolean contains(@CheckForNull Object o) {
+      public boolean contains(@CheckForNull @UnknownSignedness Object o) {
         if (o instanceof Set) {
           Set<?> s = (Set<?>) o;
           return s.size() == size && index.keySet().containsAll(s);
@@ -1710,7 +1713,7 @@ protected Set<E> computeNext() {
             final BitSet copy = (BitSet) bits.clone();
             return new AbstractSet<E>() {
               @Override
-              public boolean contains(@CheckForNull Object o) {
+              public boolean contains(@CheckForNull @UnknownSignedness Object o) {
                 Integer i = index.get(o);
                 return i != null && copy.get(i);
               }
@@ -2123,13 +2126,14 @@ public Iterator<E> iterator() {
     }
 
     @Override
-    public @Nullable Object[] toArray() {
+    @SuppressWarnings("nullness:return")
+    public @PolyNull @PolySigned Object[] toArray(Sets.DescendingSet<@PolyNull @PolySigned E> this) {
       return standardToArray();
     }
 
     @Override
-    @SuppressWarnings("nullness") // b/192354773 in our checker affects toArray declarations
-    public <T extends @Nullable Object> T[] toArray(T[] array) {
+    @SuppressWarnings("nullness:return")
+    public <T extends @Nullable @UnknownSignedness Object> T[] toArray(@PolyNull T[] array) {
       return standardToArray(array);
     }
 
diff --git a/guava/src/com/google/common/collect/Synchronized.java b/guava/src/com/google/common/collect/Synchronized.java
index 1089c9e99ad2..29b201415ef8 100644
--- a/guava/src/com/google/common/collect/Synchronized.java
+++ b/guava/src/com/google/common/collect/Synchronized.java
@@ -48,7 +48,11 @@
 import java.util.function.UnaryOperator;
 import java.util.stream.Stream;
 import javax.annotation.CheckForNull;
+import org.checkerframework.checker.nullness.qual.KeyFor;
 import org.checkerframework.checker.nullness.qual.Nullable;
+import org.checkerframework.checker.nullness.qual.PolyNull;
+import org.checkerframework.checker.signedness.qual.PolySigned;
+import org.checkerframework.checker.signedness.qual.UnknownSignedness;
 import org.checkerframework.dataflow.qual.Pure;
 import org.checkerframework.dataflow.qual.SideEffectFree;
 import org.checkerframework.framework.qual.AnnotatedFor;
@@ -160,7 +164,7 @@ public void clear() {
 
     @Pure
     @Override
-    public boolean contains(@CheckForNull Object o) {
+    public boolean contains(@CheckForNull @UnknownSignedness Object o) {
       synchronized (mutex) {
         return delegate().contains(o);
       }
@@ -216,7 +220,7 @@ public void forEach(Consumer<? super E> action) {
     }
 
     @Override
-    public boolean remove(@CheckForNull Object o) {
+    public boolean remove(@CheckForNull @UnknownSignedness Object o) {
       synchronized (mutex) {
         return delegate().remove(o);
       }
@@ -252,15 +256,16 @@ public int size() {
     }
 
     @Override
-    public @Nullable Object[] toArray() {
+    @SuppressWarnings("nullness:return")
+    public @PolyNull @PolySigned Object[] toArray() {
       synchronized (mutex) {
         return delegate().toArray();
       }
     }
 
     @Override
-    @SuppressWarnings("nullness") // b/192354773 in our checker affects toArray declarations
-    public <T extends @Nullable Object> T[] toArray(T[] a) {
+    @SuppressWarnings("nullness:return")
+    public <T extends @Nullable @UnknownSignedness Object> T[] toArray(@PolyNull T[] a) {
       synchronized (mutex) {
         return delegate().toArray(a);
       }
@@ -288,7 +293,7 @@ Set<E> delegate() {
 
     @Pure
     @Override
-    public boolean equals(@CheckForNull Object o) {
+    public boolean equals(@CheckForNull @UnknownSignedness Object o) {
       if (o == this) {
         return true;
       }
@@ -417,7 +422,7 @@ public E get(int index) {
 
     @Pure
     @Override
-    public int indexOf(@CheckForNull Object o) {
+    public int indexOf(@CheckForNull @UnknownSignedness Object o) {
       synchronized (mutex) {
         return delegate().indexOf(o);
       }
@@ -425,7 +430,7 @@ public int indexOf(@CheckForNull Object o) {
 
     @Pure
     @Override
-    public int lastIndexOf(@CheckForNull Object o) {
+    public int lastIndexOf(@CheckForNull @UnknownSignedness Object o) {
       synchronized (mutex) {
         return delegate().lastIndexOf(o);
       }
@@ -479,7 +484,7 @@ public List<E> subList(int fromIndex, int toIndex) {
 
     @Pure
     @Override
-    public boolean equals(@CheckForNull Object o) {
+    public boolean equals(@CheckForNull @UnknownSignedness Object o) {
       if (o == this) {
         return true;
       }
@@ -589,7 +594,7 @@ public Set<Multiset.Entry<E>> entrySet() {
 
     @Pure
     @Override
-    public boolean equals(@CheckForNull Object o) {
+    public boolean equals(@CheckForNull @UnknownSignedness Object o) {
       if (o == this) {
         return true;
       }
@@ -1023,7 +1028,7 @@ public Collection<V> getValue() {
     // See Collections.CheckedMap.CheckedEntrySet for details on attacks.
 
     @Override
-    public @Nullable Object[] toArray() {
+    public @PolyNull @PolySigned Object[] toArray() {
       synchronized (mutex) {
         /*
          * toArrayImpl returns `@Nullable Object[]` rather than `Object[]` but only because it can
@@ -1037,8 +1042,8 @@ public Collection<V> getValue() {
     }
 
     @Override
-    @SuppressWarnings("nullness") // b/192354773 in our checker affects toArray declarations
-    public <T extends @Nullable Object> T[] toArray(T[] array) {
+    //@SuppressWarnings("nullness") // b/192354773 in our checker affects toArray declarations
+    public <T extends @Nullable @UnknownSignedness Object> T[] toArray(T[] array) {
       synchronized (mutex) {
         return ObjectArrays.toArrayImpl(delegate(), array);
       }
@@ -1046,7 +1051,7 @@ public Collection<V> getValue() {
 
     @Pure
     @Override
-    public boolean contains(@CheckForNull Object o) {
+    public boolean contains(@CheckForNull @UnknownSignedness Object o) {
       synchronized (mutex) {
         return Maps.containsEntryImpl(delegate(), o);
       }
@@ -1062,7 +1067,7 @@ public boolean containsAll(Collection<?> c) {
 
     @Pure
     @Override
-    public boolean equals(@CheckForNull Object o) {
+    public boolean equals(@CheckForNull @UnknownSignedness Object o) {
       if (o == this) {
         return true;
       }
@@ -1072,7 +1077,7 @@ public boolean equals(@CheckForNull Object o) {
     }
 
     @Override
-    public boolean remove(@CheckForNull Object o) {
+    public boolean remove(@CheckForNull @UnknownSignedness Object o) {
       synchronized (mutex) {
         return Maps.removeEntryImpl(delegate(), o);
       }
@@ -1126,7 +1131,7 @@ public void clear() {
 
     @Pure
     @Override
-    public boolean containsKey(@CheckForNull Object key) {
+    public boolean containsKey(@CheckForNull @UnknownSignedness Object key) {
       synchronized (mutex) {
         return delegate().containsKey(key);
       }
@@ -1134,7 +1139,7 @@ public boolean containsKey(@CheckForNull Object key) {
 
     @Pure
     @Override
-    public boolean containsValue(@CheckForNull Object value) {
+    public boolean containsValue(@CheckForNull @UnknownSignedness Object value) {
       synchronized (mutex) {
         return delegate().containsValue(value);
       }
@@ -1142,7 +1147,7 @@ public boolean containsValue(@CheckForNull Object value) {
 
     @SideEffectFree
     @Override
-    public Set<Map.Entry<K, V>> entrySet() {
+    public Set<Map.Entry<@KeyFor({"this"}) K, V>> entrySet() {
       synchronized (mutex) {
         if (entrySet == null) {
           entrySet = set(delegate().entrySet(), mutex);
@@ -1160,7 +1165,7 @@ public void forEach(BiConsumer<? super K, ? super V> action) {
 
     @Override
     @CheckForNull
-    public V get(@CheckForNull Object key) {
+    public V get(@CheckForNull @UnknownSignedness Object key) {
       synchronized (mutex) {
         return delegate().get(key);
       }
@@ -1169,7 +1174,7 @@ public V get(@CheckForNull Object key) {
     @Pure
     @Override
     @CheckForNull
-    public V getOrDefault(@CheckForNull Object key, @CheckForNull V defaultValue) {
+    public V getOrDefault(@CheckForNull @UnknownSignedness Object key, @CheckForNull V defaultValue) {
       synchronized (mutex) {
         return delegate().getOrDefault(key, defaultValue);
       }
@@ -1271,7 +1276,7 @@ public void replaceAll(BiFunction<? super K, ? super V, ? extends V> function) {
 
     @Override
     @CheckForNull
-    public V remove(@CheckForNull Object key) {
+    public V remove(@CheckForNull @UnknownSignedness Object key) {
       synchronized (mutex) {
         return delegate().remove(key);
       }
@@ -1279,7 +1284,7 @@ public V remove(@CheckForNull Object key) {
 
     @Pure
     @Override
-    public boolean remove(@CheckForNull Object key, @CheckForNull Object value) {
+    public boolean remove(@CheckForNull @UnknownSignedness Object key, @CheckForNull @UnknownSignedness Object value) {
       synchronized (mutex) {
         return delegate().remove(key, value);
       }
@@ -1456,7 +1461,7 @@ private static class SynchronizedAsMap<K extends @Nullable Object, V extends @Nu
 
     @Override
     @CheckForNull
-    public Collection<V> get(@CheckForNull Object key) {
+    public Collection<V> get(@CheckForNull @UnknownSignedness Object key) {
       synchronized (mutex) {
         Collection<V> collection = super.get(key);
         return (collection == null) ? null : typePreservingCollection(collection, mutex);
@@ -1487,7 +1492,7 @@ public Collection<Collection<V>> values() {
 
     @Pure
     @Override
-    public boolean containsValue(@CheckForNull Object o) {
+    public boolean containsValue(@CheckForNull @UnknownSignedness Object o) {
       // values() and its contains() method are both synchronized.
       return values().contains(o);
     }
@@ -1518,14 +1523,14 @@ Collection<V> transform(Collection<V> from) {
   //Suppressed due to annotations on toArray
   @SuppressWarnings("nullness")
   @Override
-  public @Nullable Object[] toArray() { return super.toArray(); }
+  public @Nullable @PolySigned Object[] toArray() { return super.toArray(); }
 
   @SuppressWarnings("nullness")
   @Override public <T> T[] toArray(T[] arg0) { return super.toArray(arg0); }
 
   @Pure
   @Override
-  public boolean contains(@Nullable Object arg0) { return super.contains(arg0); }
+  public boolean contains(@Nullable @UnknownSignedness Object arg0) { return super.contains(arg0); }
 
   @SuppressWarnings("nullness")
   @Pure
@@ -1533,7 +1538,7 @@ Collection<V> transform(Collection<V> from) {
   public boolean containsAll(Collection<?> arg0) { return super.containsAll(arg0); }
 
   @Override
-  public boolean remove(@Nullable Object arg0) { return super.remove(arg0); }
+  public boolean remove(@Nullable @UnknownSignedness Object arg0) { return super.remove(arg0); }
 
   @SuppressWarnings("nullness")
   @Override
diff --git a/guava/src/com/google/common/graph/AbstractBaseGraph.java b/guava/src/com/google/common/graph/AbstractBaseGraph.java
index 797468b7aa92..63ddcec1bde9 100644
--- a/guava/src/com/google/common/graph/AbstractBaseGraph.java
+++ b/guava/src/com/google/common/graph/AbstractBaseGraph.java
@@ -31,6 +31,8 @@
 import java.util.Set;
 import javax.annotation.CheckForNull;
 
+import org.checkerframework.checker.signedness.qual.UnknownSignedness;
+
 /**
  * This class provides a skeletal implementation of {@link BaseGraph}.
  *
@@ -76,7 +78,7 @@ public int size() {
       }
 
       @Override
-      public boolean remove(@CheckForNull Object o) {
+      public boolean remove(@CheckForNull @UnknownSignedness Object o) {
         throw new UnsupportedOperationException();
       }
 
@@ -85,7 +87,7 @@ public boolean remove(@CheckForNull Object o) {
       // Graph<LinkedList>.
       @SuppressWarnings("unchecked")
       @Override
-      public boolean contains(@CheckForNull Object obj) {
+      public boolean contains(@CheckForNull @UnknownSignedness Object obj) {
         if (!(obj instanceof EndpointPair)) {
           return false;
         }
diff --git a/guava/src/com/google/common/graph/AbstractDirectedNetworkConnections.java b/guava/src/com/google/common/graph/AbstractDirectedNetworkConnections.java
index ac452d4d610a..4b221bfbc58f 100644
--- a/guava/src/com/google/common/graph/AbstractDirectedNetworkConnections.java
+++ b/guava/src/com/google/common/graph/AbstractDirectedNetworkConnections.java
@@ -33,6 +33,8 @@
 import java.util.Set;
 import javax.annotation.CheckForNull;
 
+import org.checkerframework.checker.signedness.qual.UnknownSignedness;
+
 /**
  * A base implementation of {@link NetworkConnections} for directed networks.
  *
@@ -80,7 +82,7 @@ public int size() {
       }
 
       @Override
-      public boolean contains(@CheckForNull Object obj) {
+      public boolean contains(@CheckForNull @UnknownSignedness Object obj) {
         return inEdgeMap.containsKey(obj) || outEdgeMap.containsKey(obj);
       }
     };
diff --git a/guava/src/com/google/common/graph/AbstractNetwork.java b/guava/src/com/google/common/graph/AbstractNetwork.java
index d6bf4c36c6fe..363fb4393dbc 100644
--- a/guava/src/com/google/common/graph/AbstractNetwork.java
+++ b/guava/src/com/google/common/graph/AbstractNetwork.java
@@ -37,6 +37,8 @@
 import java.util.Set;
 import javax.annotation.CheckForNull;
 
+import org.checkerframework.checker.signedness.qual.UnknownSignedness;
+
 /**
  * This class provides a skeletal implementation of {@link Network}. It is recommended to extend
  * this class rather than implement {@link Network} directly.
@@ -91,7 +93,7 @@ public int size() {
           // Network<LinkedList>.
           @SuppressWarnings("unchecked")
           @Override
-          public boolean contains(@CheckForNull Object obj) {
+          public boolean contains(@CheckForNull @UnknownSignedness Object obj) {
             if (!(obj instanceof EndpointPair)) {
               return false;
             }
diff --git a/guava/src/com/google/common/graph/DirectedGraphConnections.java b/guava/src/com/google/common/graph/DirectedGraphConnections.java
index 0feb973f3f79..dc6021c5c726 100644
--- a/guava/src/com/google/common/graph/DirectedGraphConnections.java
+++ b/guava/src/com/google/common/graph/DirectedGraphConnections.java
@@ -42,6 +42,8 @@
 import java.util.concurrent.atomic.AtomicBoolean;
 import javax.annotation.CheckForNull;
 
+import org.checkerframework.checker.signedness.qual.UnknownSignedness;
+
 /**
  * An implementation of {@link GraphConnections} for directed graphs.
  *
@@ -263,7 +265,7 @@ public int size() {
         }
 
         @Override
-        public boolean contains(@CheckForNull Object obj) {
+        public boolean contains(@CheckForNull @UnknownSignedness Object obj) {
           return adjacentNodeValues.containsKey(obj);
         }
       };
@@ -314,7 +316,7 @@ public int size() {
       }
 
       @Override
-      public boolean contains(@CheckForNull Object obj) {
+      public boolean contains(@CheckForNull @UnknownSignedness Object obj) {
         return isPredecessor(adjacentNodeValues.get(obj));
       }
     };
@@ -364,7 +366,7 @@ public int size() {
       }
 
       @Override
-      public boolean contains(@CheckForNull Object obj) {
+      public boolean contains(@CheckForNull @UnknownSignedness Object obj) {
         return isSuccessor(adjacentNodeValues.get(obj));
       }
     };
diff --git a/guava/src/com/google/common/graph/EdgesConnecting.java b/guava/src/com/google/common/graph/EdgesConnecting.java
index 797970ba29c1..4c7aa9fc5dcf 100644
--- a/guava/src/com/google/common/graph/EdgesConnecting.java
+++ b/guava/src/com/google/common/graph/EdgesConnecting.java
@@ -25,6 +25,8 @@
 import java.util.Map;
 import javax.annotation.CheckForNull;
 
+import org.checkerframework.checker.signedness.qual.UnknownSignedness;
+
 /**
  * A class to represent the set of edges connecting an (implicit) origin node to a target node.
  *
@@ -59,7 +61,7 @@ public int size() {
   }
 
   @Override
-  public boolean contains(@CheckForNull Object edge) {
+  public boolean contains(@CheckForNull @UnknownSignedness Object edge) {
     E connectingEdge = getConnectingEdge();
     return (connectingEdge != null && connectingEdge.equals(edge));
   }
diff --git a/guava/src/com/google/common/graph/IncidentEdgeSet.java b/guava/src/com/google/common/graph/IncidentEdgeSet.java
index ac94b65779d4..e46cbc5c3ce1 100644
--- a/guava/src/com/google/common/graph/IncidentEdgeSet.java
+++ b/guava/src/com/google/common/graph/IncidentEdgeSet.java
@@ -20,6 +20,8 @@
 import java.util.Set;
 import javax.annotation.CheckForNull;
 
+import org.checkerframework.checker.signedness.qual.UnknownSignedness;
+
 /**
  * Abstract base class for an incident edges set that allows different implementations of {@link
  * AbstractSet#iterator()}.
@@ -35,7 +37,7 @@ abstract class IncidentEdgeSet<N> extends AbstractSet<EndpointPair<N>> {
   }
 
   @Override
-  public boolean remove(@CheckForNull Object o) {
+  public boolean remove(@CheckForNull @UnknownSignedness Object o) {
     throw new UnsupportedOperationException();
   }
 
@@ -51,7 +53,7 @@ public int size() {
   }
 
   @Override
-  public boolean contains(@CheckForNull Object obj) {
+  public boolean contains(@CheckForNull @UnknownSignedness Object obj) {
     if (!(obj instanceof EndpointPair)) {
       return false;
     }
diff --git a/guava/src/com/google/common/graph/MapIteratorCache.java b/guava/src/com/google/common/graph/MapIteratorCache.java
index 05cdde8c3f12..a1c2a9d85ddf 100644
--- a/guava/src/com/google/common/graph/MapIteratorCache.java
+++ b/guava/src/com/google/common/graph/MapIteratorCache.java
@@ -27,6 +27,8 @@
 import java.util.Set;
 import javax.annotation.CheckForNull;
 
+import org.checkerframework.checker.signedness.qual.UnknownSignedness;
+
 /**
  * A map-like data structure that wraps a backing map and caches values while iterating through
  * {@link #unmodifiableKeySet()}. By design, the cache is cleared when this structure is mutated. If
@@ -131,7 +133,7 @@ public int size() {
       }
 
       @Override
-      public boolean contains(@CheckForNull Object key) {
+      public boolean contains(@CheckForNull @UnknownSignedness Object key) {
         return containsKey(key);
       }
     };
diff --git a/guava/src/com/google/common/graph/MultiEdgesConnecting.java b/guava/src/com/google/common/graph/MultiEdgesConnecting.java
index 620f986a555a..141b97f76201 100644
--- a/guava/src/com/google/common/graph/MultiEdgesConnecting.java
+++ b/guava/src/com/google/common/graph/MultiEdgesConnecting.java
@@ -26,6 +26,8 @@
 import java.util.Map.Entry;
 import javax.annotation.CheckForNull;
 
+import org.checkerframework.checker.signedness.qual.UnknownSignedness;
+
 /**
  * A class to represent the set of edges connecting an (implicit) origin node to a target node.
  *
@@ -65,7 +67,7 @@ protected E computeNext() {
   }
 
   @Override
-  public boolean contains(@CheckForNull Object edge) {
+  public boolean contains(@CheckForNull @UnknownSignedness Object edge) {
     return targetNode.equals(outEdgeToNode.get(edge));
   }
 }
diff --git a/guava/src/com/google/common/hash/HashingOutputStream.java b/guava/src/com/google/common/hash/HashingOutputStream.java
index a96f9e2e991b..544abd9b04e8 100644
--- a/guava/src/com/google/common/hash/HashingOutputStream.java
+++ b/guava/src/com/google/common/hash/HashingOutputStream.java
@@ -22,6 +22,7 @@
 import java.io.OutputStream;
 import org.checkerframework.checker.index.qual.LTLengthOf;
 import org.checkerframework.checker.index.qual.NonNegative;
+import org.checkerframework.checker.signedness.qual.PolySigned;
 
 /**
  * An {@link OutputStream} that maintains a hash of the data written to it.
@@ -50,15 +51,15 @@ public HashingOutputStream(HashFunction hashFunction, OutputStream out) {
   }
 
   @Override
-  public void write(int b) throws IOException {
+  public void write(@PolySigned int b) throws IOException {
     hasher.putByte((byte) b);
     out.write(b);
   }
 
-  @SuppressWarnings("override.param.invalid")//FilterOutputStream#write() should be annotated as
+  //@SuppressWarnings("override.param.invalid")//FilterOutputStream#write() should be annotated as
   // void write(byte b[], @NonNegative @LTLengthOf(value = "#1",offset = "#3 - 1") int off, @NonNegative @LTLengthOf(value = "#1",offset = "#2 - 1") int len)
   @Override
-  public void write(byte[] bytes, @NonNegative @LTLengthOf(value = "#1",offset = "#3 - 1") int off, @NonNegative @LTLengthOf(value = "#1",offset = "#2 - 1") int len) throws IOException {
+  public void write(@PolySigned byte[] bytes, @NonNegative @LTLengthOf(value = "#1",offset = "#3 - 1") int off, @NonNegative @LTLengthOf(value = "#1",offset = "#2 - 1") int len) throws IOException {
     hasher.putBytes(bytes, off, len);
     out.write(bytes, off, len);
   }
diff --git a/guava/src/com/google/common/io/FileBackedOutputStream.java b/guava/src/com/google/common/io/FileBackedOutputStream.java
index 61a020e4e58e..422b3c2132e0 100644
--- a/guava/src/com/google/common/io/FileBackedOutputStream.java
+++ b/guava/src/com/google/common/io/FileBackedOutputStream.java
@@ -33,6 +33,7 @@
 import org.checkerframework.checker.index.qual.LTLengthOf;
 import org.checkerframework.checker.index.qual.NonNegative;
 import org.checkerframework.checker.nullness.qual.Nullable;
+import org.checkerframework.checker.signedness.qual.PolySigned;
 
 /**
  * An {@link OutputStream} that starts buffering to a byte array, but switches to file buffering
@@ -196,18 +197,18 @@ public synchronized void reset() throws IOException {
   }
 
   @Override
-  public synchronized void write(int b) throws IOException {
+  public synchronized void write(@PolySigned int b) throws IOException {
     update(1);
     out.write(b);
   }
 
   @Override
-  public synchronized void write(byte[] b) throws IOException {
+  public synchronized void write(@PolySigned byte[] b) throws IOException {
     write(b, 0, b.length);
   }
 
   @Override
-  public synchronized void write(byte[] b, @IndexOrHigh("#1") int off, @NonNegative @LTLengthOf(value = "#1", offset = "#2 - 1") int len) throws IOException {
+  public synchronized void write(@PolySigned byte[] b, @IndexOrHigh("#1") int off, @NonNegative @LTLengthOf(value = "#1", offset = "#2 - 1") int len) throws IOException {
     update(len);
     out.write(b, off, len);
   }
diff --git a/guava/src/com/google/common/io/LittleEndianDataOutputStream.java b/guava/src/com/google/common/io/LittleEndianDataOutputStream.java
index f913fa2592b9..30420bd12d01 100644
--- a/guava/src/com/google/common/io/LittleEndianDataOutputStream.java
+++ b/guava/src/com/google/common/io/LittleEndianDataOutputStream.java
@@ -18,14 +18,15 @@
 import com.google.common.annotations.GwtIncompatible;
 import com.google.common.base.Preconditions;
 import com.google.common.primitives.Longs;
-import org.checkerframework.checker.index.qual.IndexOrHigh;
-import org.checkerframework.checker.index.qual.LTLengthOf;
-import org.checkerframework.checker.index.qual.NonNegative;
 import java.io.DataOutput;
 import java.io.DataOutputStream;
 import java.io.FilterOutputStream;
 import java.io.IOException;
 import java.io.OutputStream;
+import org.checkerframework.checker.index.qual.IndexOrHigh;
+import org.checkerframework.checker.index.qual.LTLengthOf;
+import org.checkerframework.checker.index.qual.NonNegative;
+import org.checkerframework.checker.signedness.qual.PolySigned;
 
 /**
  * An implementation of {@link DataOutput} that uses little-endian byte ordering for writing {@code
@@ -53,7 +54,7 @@ public LittleEndianDataOutputStream(OutputStream out) {
   }
 
   @Override
-  public void write(byte[] b, @IndexOrHigh("#1") int off, @NonNegative @LTLengthOf(value = "#1", offset = "#2 - 1") int len) throws IOException {
+  public void write(@PolySigned byte[] b, @IndexOrHigh("#1") int off, @NonNegative @LTLengthOf(value = "#1", offset = "#2 - 1") int len) throws IOException {
     // Override slow FilterOutputStream impl
     out.write(b, off, len);
   }
diff --git a/guava/src/com/google/common/reflect/MutableTypeToInstanceMap.java b/guava/src/com/google/common/reflect/MutableTypeToInstanceMap.java
index 9542e0a7ed51..fe6a25759aff 100644
--- a/guava/src/com/google/common/reflect/MutableTypeToInstanceMap.java
+++ b/guava/src/com/google/common/reflect/MutableTypeToInstanceMap.java
@@ -28,6 +28,9 @@
 import java.util.Set;
 import javax.annotation.CheckForNull;
 import org.checkerframework.checker.nullness.qual.Nullable;
+import org.checkerframework.checker.nullness.qual.PolyNull;
+import org.checkerframework.checker.signedness.qual.PolySigned;
+import org.checkerframework.checker.signedness.qual.UnknownSignedness;
 
 /**
  * A mutable type-to-instance map. See also {@link ImmutableTypeToInstanceMap}.
@@ -137,7 +140,7 @@ public Iterator<Entry<K, V>> iterator() {
         }
 
         @Override
-        public Object[] toArray() {
+        public @PolyNull @PolySigned Object[] toArray() {
           /*
            * standardToArray returns `@Nullable Object[]` rather than `Object[]` but only because it
            * can be used with collections that may contain null. This collection is a collection of
@@ -151,7 +154,7 @@ public Object[] toArray() {
 
         @Override
         @SuppressWarnings("nullness") // b/192354773 in our checker affects toArray declarations
-        public <T extends @Nullable Object> T[] toArray(T[] array) {
+        public <T extends @Nullable @UnknownSignedness Object> T[] toArray(T[] array) {
           return standardToArray(array);
         }
       };
diff --git a/guava/src/com/google/common/util/concurrent/AbstractListeningExecutorService.java b/guava/src/com/google/common/util/concurrent/AbstractListeningExecutorService.java
index fd5c5c911533..85586939f3bc 100644
--- a/guava/src/com/google/common/util/concurrent/AbstractListeningExecutorService.java
+++ b/guava/src/com/google/common/util/concurrent/AbstractListeningExecutorService.java
@@ -21,6 +21,7 @@
 import java.util.concurrent.Callable;
 import java.util.concurrent.RunnableFuture;
 import org.checkerframework.checker.nullness.qual.Nullable;
+import org.checkerframework.checker.signedness.qual.UnknownSignedness;
 
 /**
  * Abstract {@link ListeningExecutorService} implementation that creates {@link ListenableFuture}
@@ -42,14 +43,14 @@ public abstract class AbstractListeningExecutorService extends AbstractExecutorS
 
   /** @since 19.0 (present with return type {@code ListenableFutureTask} since 14.0) */
   @Override
-  protected final <T extends @Nullable Object> RunnableFuture<T> newTaskFor(
+  protected final <T extends @Nullable @UnknownSignedness Object> RunnableFuture<T> newTaskFor(
       Runnable runnable, @ParametricNullness T value) {
     return TrustedListenableFutureTask.create(runnable, value);
   }
 
   /** @since 19.0 (present with return type {@code ListenableFutureTask} since 14.0) */
   @Override
-  protected final <T extends @Nullable Object> RunnableFuture<T> newTaskFor(Callable<T> callable) {
+  protected final <T extends @Nullable @UnknownSignedness Object> RunnableFuture<T> newTaskFor(Callable<T> callable) {
     return TrustedListenableFutureTask.create(callable);
   }
 
@@ -59,13 +60,13 @@ public ListenableFuture<?> submit(Runnable task) {
   }
 
   @Override
-  public <T extends @Nullable Object> ListenableFuture<T> submit(
+  public <T extends @Nullable @UnknownSignedness Object> ListenableFuture<T> submit(
       Runnable task, @ParametricNullness T result) {
     return (ListenableFuture<T>) super.submit(task, result);
   }
 
   @Override
-  public <T extends @Nullable Object> ListenableFuture<T> submit(Callable<T> task) {
+  public <T extends @Nullable @UnknownSignedness Object> ListenableFuture<T> submit(Callable<T> task) {
     return (ListenableFuture<T>) super.submit(task);
   }
 }
diff --git a/guava/src/com/google/common/util/concurrent/ForwardingExecutorService.java b/guava/src/com/google/common/util/concurrent/ForwardingExecutorService.java
index ed78b8685694..4da0683b6bae 100644
--- a/guava/src/com/google/common/util/concurrent/ForwardingExecutorService.java
+++ b/guava/src/com/google/common/util/concurrent/ForwardingExecutorService.java
@@ -26,6 +26,7 @@
 import java.util.concurrent.TimeUnit;
 import java.util.concurrent.TimeoutException;
 import org.checkerframework.checker.nullness.qual.Nullable;
+import org.checkerframework.checker.signedness.qual.UnknownSignedness;
 
 /**
  * An executor service which forwards all its method calls to another executor service. Subclasses
@@ -52,26 +53,26 @@ public boolean awaitTermination(long timeout, TimeUnit unit) throws InterruptedE
   }
 
   @Override
-  public <T extends @Nullable Object> List<Future<T>> invokeAll(
+  public <T extends @Nullable @UnknownSignedness Object> List<Future<T>> invokeAll(
       Collection<? extends Callable<T>> tasks) throws InterruptedException {
     return delegate().invokeAll(tasks);
   }
 
   @Override
-  public <T extends @Nullable Object> List<Future<T>> invokeAll(
+  public <T extends @Nullable @UnknownSignedness Object> List<Future<T>> invokeAll(
       Collection<? extends Callable<T>> tasks, long timeout, TimeUnit unit)
       throws InterruptedException {
     return delegate().invokeAll(tasks, timeout, unit);
   }
 
   @Override
-  public <T extends @Nullable Object> T invokeAny(Collection<? extends Callable<T>> tasks)
+  public <T extends @Nullable @UnknownSignedness Object> T invokeAny(Collection<? extends Callable<T>> tasks)
       throws InterruptedException, ExecutionException {
     return delegate().invokeAny(tasks);
   }
 
   @Override
-  public <T extends @Nullable Object> T invokeAny(
+  public <T extends @Nullable @UnknownSignedness Object> T invokeAny(
       Collection<? extends Callable<T>> tasks, long timeout, TimeUnit unit)
       throws InterruptedException, ExecutionException, TimeoutException {
     return delegate().invokeAny(tasks, timeout, unit);
@@ -103,7 +104,7 @@ public void execute(Runnable command) {
   }
 
   @Override
-  public <T extends @Nullable Object> Future<T> submit(Callable<T> task) {
+  public <T extends @Nullable @UnknownSignedness Object> Future<T> submit(Callable<T> task) {
     return delegate().submit(task);
   }
 
@@ -113,7 +114,7 @@ public Future<?> submit(Runnable task) {
   }
 
   @Override
-  public <T extends @Nullable Object> Future<T> submit(
+  public <T extends @Nullable @UnknownSignedness Object> Future<T> submit(
       Runnable task, @ParametricNullness T result) {
     return delegate().submit(task, result);
   }
diff --git a/guava/src/com/google/common/util/concurrent/ForwardingListeningExecutorService.java b/guava/src/com/google/common/util/concurrent/ForwardingListeningExecutorService.java
index fe25b867af4c..06f29e91556c 100644
--- a/guava/src/com/google/common/util/concurrent/ForwardingListeningExecutorService.java
+++ b/guava/src/com/google/common/util/concurrent/ForwardingListeningExecutorService.java
@@ -18,6 +18,7 @@
 import com.google.errorprone.annotations.CanIgnoreReturnValue;
 import java.util.concurrent.Callable;
 import org.checkerframework.checker.nullness.qual.Nullable;
+import org.checkerframework.checker.signedness.qual.UnknownSignedness;
 
 /**
  * A listening executor service which forwards all its method calls to another listening executor
@@ -40,7 +41,7 @@ protected ForwardingListeningExecutorService() {}
   protected abstract ListeningExecutorService delegate();
 
   @Override
-  public <T extends @Nullable Object> ListenableFuture<T> submit(Callable<T> task) {
+  public <T extends @Nullable @UnknownSignedness Object> ListenableFuture<T> submit(Callable<T> task) {
     return delegate().submit(task);
   }
 
@@ -50,7 +51,7 @@ public ListenableFuture<?> submit(Runnable task) {
   }
 
   @Override
-  public <T extends @Nullable Object> ListenableFuture<T> submit(
+  public <T extends @Nullable @UnknownSignedness Object> ListenableFuture<T> submit(
       Runnable task, @ParametricNullness T result) {
     return delegate().submit(task, result);
   }
diff --git a/guava/src/com/google/common/util/concurrent/ListeningExecutorService.java b/guava/src/com/google/common/util/concurrent/ListeningExecutorService.java
index 83ea759f8e74..7674103d7eaf 100644
--- a/guava/src/com/google/common/util/concurrent/ListeningExecutorService.java
+++ b/guava/src/com/google/common/util/concurrent/ListeningExecutorService.java
@@ -24,6 +24,7 @@
 import java.util.concurrent.RejectedExecutionException;
 import java.util.concurrent.TimeUnit;
 import org.checkerframework.checker.nullness.qual.Nullable;
+import org.checkerframework.checker.signedness.qual.UnknownSignedness;
 
 /**
  * An {@link ExecutorService} that returns {@link ListenableFuture} instances. To create an instance
@@ -44,7 +45,7 @@ public interface ListeningExecutorService extends ExecutorService {
    * @throws RejectedExecutionException {@inheritDoc}
    */
   @Override
-  <T extends @Nullable Object> ListenableFuture<T> submit(Callable<T> task);
+  <T extends @Nullable @UnknownSignedness Object> ListenableFuture<T> submit(Callable<T> task);
 
   /**
    * @return a {@code ListenableFuture} representing pending completion of the task
@@ -58,7 +59,7 @@ public interface ListeningExecutorService extends ExecutorService {
    * @throws RejectedExecutionException {@inheritDoc}
    */
   @Override
-  <T extends @Nullable Object> ListenableFuture<T> submit(
+  <T extends @Nullable @UnknownSignedness Object> ListenableFuture<T> submit(
       Runnable task, @ParametricNullness T result);
 
   /**
@@ -80,7 +81,7 @@ public interface ListeningExecutorService extends ExecutorService {
    * @throws NullPointerException if any task is null
    */
   @Override
-  <T extends @Nullable Object> List<Future<T>> invokeAll(Collection<? extends Callable<T>> tasks)
+  <T extends @Nullable @UnknownSignedness Object> List<Future<T>> invokeAll(Collection<? extends Callable<T>> tasks)
       throws InterruptedException;
 
   /**
@@ -103,7 +104,7 @@ public interface ListeningExecutorService extends ExecutorService {
    * @throws NullPointerException if any task is null
    */
   @Override
-  <T extends @Nullable Object> List<Future<T>> invokeAll(
+  <T extends @Nullable @UnknownSignedness Object> List<Future<T>> invokeAll(
       Collection<? extends Callable<T>> tasks, long timeout, TimeUnit unit)
       throws InterruptedException;
 }
diff --git a/guava/src/com/google/common/util/concurrent/ListeningScheduledExecutorService.java b/guava/src/com/google/common/util/concurrent/ListeningScheduledExecutorService.java
index 25185b91a454..2d91771ed770 100644
--- a/guava/src/com/google/common/util/concurrent/ListeningScheduledExecutorService.java
+++ b/guava/src/com/google/common/util/concurrent/ListeningScheduledExecutorService.java
@@ -22,6 +22,7 @@
 import java.util.concurrent.ScheduledExecutorService;
 import java.util.concurrent.TimeUnit;
 import org.checkerframework.checker.nullness.qual.Nullable;
+import org.checkerframework.checker.signedness.qual.UnknownSignedness;
 
 /**
  * A {@link ScheduledExecutorService} that returns {@link ListenableFuture} instances from its
@@ -52,7 +53,7 @@ default ListenableScheduledFuture<?> schedule(Runnable command, Duration delay)
 
   /** @since 15.0 (previously returned ScheduledFuture) */
   @Override
-  <V extends @Nullable Object> ListenableScheduledFuture<V> schedule(
+  <V extends @Nullable @UnknownSignedness Object> ListenableScheduledFuture<V> schedule(
       Callable<V> callable, long delay, TimeUnit unit);
 
   /**
diff --git a/guava/src/com/google/common/util/concurrent/MoreExecutors.java b/guava/src/com/google/common/util/concurrent/MoreExecutors.java
index 90776bc9e69b..f7f356c29183 100644
--- a/guava/src/com/google/common/util/concurrent/MoreExecutors.java
+++ b/guava/src/com/google/common/util/concurrent/MoreExecutors.java
@@ -52,6 +52,7 @@
 import java.util.concurrent.TimeUnit;
 import java.util.concurrent.TimeoutException;
 import org.checkerframework.checker.nullness.qual.Nullable;
+import org.checkerframework.checker.signedness.qual.UnknownSignedness;
 
 /**
  * Factory and utility methods for {@link java.util.concurrent.Executor}, {@link ExecutorService},
@@ -657,7 +658,7 @@ public ListenableScheduledFuture<?> schedule(Runnable command, long delay, TimeU
     }
 
     @Override
-    public <V extends @Nullable Object> ListenableScheduledFuture<V> schedule(
+    public <V extends @Nullable @UnknownSignedness Object> ListenableScheduledFuture<V> schedule(
         Callable<V> callable, long delay, TimeUnit unit) {
       TrustedListenableFutureTask<V> task = TrustedListenableFutureTask.create(callable);
       ScheduledFuture<?> scheduled = delegate.schedule(task, delay, unit);
diff --git a/guava/src/com/google/common/util/concurrent/WrappingExecutorService.java b/guava/src/com/google/common/util/concurrent/WrappingExecutorService.java
index 5a3c3927a6b9..55631ca668df 100644
--- a/guava/src/com/google/common/util/concurrent/WrappingExecutorService.java
+++ b/guava/src/com/google/common/util/concurrent/WrappingExecutorService.java
@@ -30,6 +30,7 @@
 import java.util.concurrent.TimeUnit;
 import java.util.concurrent.TimeoutException;
 import org.checkerframework.checker.nullness.qual.Nullable;
+import org.checkerframework.checker.signedness.qual.UnknownSignedness;
 
 /**
  * An abstract {@code ExecutorService} that allows subclasses to {@linkplain #wrapTask(Callable)
@@ -94,7 +95,7 @@ public final void execute(Runnable command) {
   }
 
   @Override
-  public final <T extends @Nullable Object> Future<T> submit(Callable<T> task) {
+  public final <T extends @Nullable @UnknownSignedness Object> Future<T> submit(Callable<T> task) {
     return delegate.submit(wrapTask(checkNotNull(task)));
   }
 
@@ -104,32 +105,32 @@ public final Future<?> submit(Runnable task) {
   }
 
   @Override
-  public final <T extends @Nullable Object> Future<T> submit(
+  public final <T extends @Nullable @UnknownSignedness Object> Future<T> submit(
       Runnable task, @ParametricNullness T result) {
     return delegate.submit(wrapTask(task), result);
   }
 
   @Override
-  public final <T extends @Nullable Object> List<Future<T>> invokeAll(
+  public final <T extends @Nullable @UnknownSignedness Object> List<Future<T>> invokeAll(
       Collection<? extends Callable<T>> tasks) throws InterruptedException {
     return delegate.invokeAll(wrapTasks(tasks));
   }
 
   @Override
-  public final <T extends @Nullable Object> List<Future<T>> invokeAll(
+  public final <T extends @Nullable @UnknownSignedness Object> List<Future<T>> invokeAll(
       Collection<? extends Callable<T>> tasks, long timeout, TimeUnit unit)
       throws InterruptedException {
     return delegate.invokeAll(wrapTasks(tasks), timeout, unit);
   }
 
   @Override
-  public final <T extends @Nullable Object> T invokeAny(Collection<? extends Callable<T>> tasks)
+  public final <T extends @Nullable @UnknownSignedness Object> T invokeAny(Collection<? extends Callable<T>> tasks)
       throws InterruptedException, ExecutionException {
     return delegate.invokeAny(wrapTasks(tasks));
   }
 
   @Override
-  public final <T extends @Nullable Object> T invokeAny(
+  public final <T extends @Nullable @UnknownSignedness Object> T invokeAny(
       Collection<? extends Callable<T>> tasks, long timeout, TimeUnit unit)
       throws InterruptedException, ExecutionException, TimeoutException {
     return delegate.invokeAny(wrapTasks(tasks), timeout, unit);
diff --git a/guava/src/com/google/common/util/concurrent/WrappingScheduledExecutorService.java b/guava/src/com/google/common/util/concurrent/WrappingScheduledExecutorService.java
index 48f23c12c7cb..391601499ac8 100644
--- a/guava/src/com/google/common/util/concurrent/WrappingScheduledExecutorService.java
+++ b/guava/src/com/google/common/util/concurrent/WrappingScheduledExecutorService.java
@@ -21,6 +21,7 @@
 import java.util.concurrent.ScheduledFuture;
 import java.util.concurrent.TimeUnit;
 import org.checkerframework.checker.nullness.qual.Nullable;
+import org.checkerframework.checker.signedness.qual.UnknownSignedness;
 
 /**
  * An abstract {@code ScheduledExecutorService} that allows subclasses to {@linkplain
@@ -48,7 +49,7 @@ public final ScheduledFuture<?> schedule(Runnable command, long delay, TimeUnit
   }
 
   @Override
-  public final <V extends @Nullable Object> ScheduledFuture<V> schedule(
+  public final <V extends @Nullable @UnknownSignedness Object> ScheduledFuture<V> schedule(
       Callable<V> task, long delay, TimeUnit unit) {
     return delegate.schedule(wrapTask(task), delay, unit);
   }

From 9272ee0247115421e346e17890bdbbf8a87bed40 Mon Sep 17 00:00:00 2001
From: Mark Roberts <markro49@users.noreply.github.com>
Date: Thu, 27 Apr 2023 07:13:24 -0700
Subject: [PATCH 12/21] add suppression justifications (#69)

Co-authored-by: Michael Ernst <mernst@cs.washington.edu>
---
 .../common/io/CountingOutputStream.java       |  3 +-
 .../google/common/primitives/Booleans.java    | 10 ++---
 .../com/google/common/primitives/Bytes.java   | 42 ++++++++++---------
 .../com/google/common/primitives/Chars.java   | 21 +++++-----
 .../common/primitives/ImmutableIntArray.java  |  7 +++-
 .../common/primitives/ImmutableLongArray.java |  7 +++-
 .../com/google/common/primitives/Ints.java    | 12 +++---
 .../com/google/common/primitives/Longs.java   | 16 +++----
 .../com/google/common/primitives/Shorts.java  | 13 +++---
 .../common/primitives/UnsignedBytes.java      | 17 ++++----
 .../common/primitives/UnsignedInteger.java    | 18 ++++----
 .../common/primitives/UnsignedInts.java       |  5 ++-
 .../common/primitives/UnsignedLongs.java      | 20 ++++-----
 13 files changed, 105 insertions(+), 86 deletions(-)

diff --git a/guava/src/com/google/common/io/CountingOutputStream.java b/guava/src/com/google/common/io/CountingOutputStream.java
index f74effab0f00..d5f64435a3c9 100644
--- a/guava/src/com/google/common/io/CountingOutputStream.java
+++ b/guava/src/com/google/common/io/CountingOutputStream.java
@@ -24,6 +24,7 @@
 import org.checkerframework.checker.index.qual.LTLengthOf;
 import org.checkerframework.checker.index.qual.NonNegative;
 import org.checkerframework.checker.signedness.qual.PolySigned;
+import org.checkerframework.checker.signedness.qual.UnknownSignedness;
 import org.checkerframework.framework.qual.AnnotatedFor;
 
 /**
@@ -60,7 +61,7 @@ public void write(@PolySigned byte[] b, @IndexOrHigh("#1") int off, @NonNegative
   }
 
   @Override
-  public void write(@PolySigned int b) throws IOException {
+  public void write(@UnknownSignedness int b) throws IOException {
     out.write(b);
     count++;
   }
diff --git a/guava/src/com/google/common/primitives/Booleans.java b/guava/src/com/google/common/primitives/Booleans.java
index c59285877a3f..4f00141fbe52 100644
--- a/guava/src/com/google/common/primitives/Booleans.java
+++ b/guava/src/com/google/common/primitives/Booleans.java
@@ -30,16 +30,16 @@
 import java.util.List;
 import java.util.RandomAccess;
 import javax.annotation.CheckForNull;
+import org.checkerframework.checker.index.qual.HasSubsequence;
 import org.checkerframework.checker.index.qual.IndexFor;
 import org.checkerframework.checker.index.qual.IndexOrHigh;
 import org.checkerframework.checker.index.qual.IndexOrLow;
 import org.checkerframework.checker.index.qual.LTEqLengthOf;
 import org.checkerframework.checker.index.qual.LTLengthOf;
+import org.checkerframework.checker.index.qual.LessThan;
 import org.checkerframework.checker.index.qual.NonNegative;
 import org.checkerframework.checker.index.qual.Positive;
 import org.checkerframework.checker.index.qual.SubstringIndexFor;
-import org.checkerframework.checker.index.qual.HasSubsequence;
-import org.checkerframework.checker.index.qual.LessThan;
 import org.checkerframework.checker.nullness.qual.Nullable;
 import org.checkerframework.checker.signedness.qual.Signed;
 import org.checkerframework.checker.signedness.qual.UnknownSignedness;
@@ -436,7 +436,7 @@ public Boolean get(@IndexFor("this") int index) {
     }
 
     @Override
-    @SuppressWarnings("signedness:cast.unsafe")
+    @SuppressWarnings("signedness:cast.unsafe") // CF bug? Boolean should always be @Signed
     public boolean contains(@CheckForNull @UnknownSignedness Object target) {
       // Overridden to prevent a ton of boxing
       return (target instanceof Boolean)
@@ -444,7 +444,7 @@ public boolean contains(@CheckForNull @UnknownSignedness Object target) {
     }
 
     @Override
-    @SuppressWarnings("signedness:cast.unsafe")
+    @SuppressWarnings("signedness:cast.unsafe") // CF bug? Boolean should always be @Signed
     public @IndexOrLow("this") int indexOf(@CheckForNull @UnknownSignedness Object target) {
       // Overridden to prevent a ton of boxing
       if (target instanceof Boolean) {
@@ -457,7 +457,7 @@ public boolean contains(@CheckForNull @UnknownSignedness Object target) {
     }
 
     @Override
-    @SuppressWarnings("signedness:cast.unsafe")
+    @SuppressWarnings("signedness:cast.unsafe") // CF bug? Boolean should always be @Signed
     public @IndexOrLow("this") int lastIndexOf(@CheckForNull @UnknownSignedness Object target) {
       // Overridden to prevent a ton of boxing
       if (target instanceof Boolean) {
diff --git a/guava/src/com/google/common/primitives/Bytes.java b/guava/src/com/google/common/primitives/Bytes.java
index 0abcee6587ed..1db3e9f36500 100644
--- a/guava/src/com/google/common/primitives/Bytes.java
+++ b/guava/src/com/google/common/primitives/Bytes.java
@@ -28,21 +28,23 @@
 import java.util.List;
 import java.util.RandomAccess;
 import javax.annotation.CheckForNull;
+import org.checkerframework.checker.index.qual.HasSubsequence;
 import org.checkerframework.checker.index.qual.IndexFor;
 import org.checkerframework.checker.index.qual.IndexOrHigh;
 import org.checkerframework.checker.index.qual.IndexOrLow;
 import org.checkerframework.checker.index.qual.LTEqLengthOf;
 import org.checkerframework.checker.index.qual.LTLengthOf;
+import org.checkerframework.checker.index.qual.LessThan;
 import org.checkerframework.checker.index.qual.NonNegative;
 import org.checkerframework.checker.index.qual.Positive;
 import org.checkerframework.checker.index.qual.SubstringIndexFor;
-import org.checkerframework.checker.index.qual.HasSubsequence;
-import org.checkerframework.checker.index.qual.LessThan;
 import org.checkerframework.checker.nullness.qual.Nullable;
+import org.checkerframework.checker.signedness.qual.PolySigned;
 import org.checkerframework.checker.signedness.qual.Signed;
 import org.checkerframework.checker.signedness.qual.UnknownSignedness;
 import org.checkerframework.common.value.qual.MinLen;
 import org.checkerframework.framework.qual.AnnotatedFor;
+import org.checkerframework.framework.qual.CFComment;
 
 /**
  * Static utility methods pertaining to {@code byte} primitives, that are not already found in
@@ -73,7 +75,7 @@ private Bytes() {}
    * @param value a primitive {@code byte} value
    * @return a hash code for the value
    */
-  public static int hashCode(byte value) {
+  public static int hashCode(@UnknownSignedness byte value) {
     return value;
   }
 
@@ -84,7 +86,7 @@ public static int hashCode(byte value) {
    * @param target a primitive {@code byte} value
    * @return {@code true} if {@code array[i] == target} for some value of {@code i}
    */
-  public static boolean contains(byte[] array, byte target) {
+  public static boolean contains(@PolySigned byte[] array, @PolySigned byte target) {
     for (byte value : array) {
       if (value == target) {
         return true;
@@ -101,12 +103,12 @@ public static boolean contains(byte[] array, byte target) {
    * @return the least index {@code i} for which {@code array[i] == target}, or {@code -1} if no
    *     such index exists.
    */
-  public static @IndexOrLow("#1") int indexOf(byte[] array, byte target) {
+  public static @IndexOrLow("#1") int indexOf(@PolySigned byte[] array, @PolySigned byte target) {
     return indexOf(array, target, 0, array.length);
   }
 
   // TODO(kevinb): consider making this public
-  private static @IndexOrLow("#1") @LessThan("#4") int indexOf(byte[] array, byte target, @IndexOrHigh("#1") int start, @IndexOrHigh("#1") int end) {
+  private static @IndexOrLow("#1") @LessThan("#4") int indexOf(@PolySigned byte[] array, @PolySigned byte target, @IndexOrHigh("#1") int start, @IndexOrHigh("#1") int end) {
     for (int i = start; i < end; i++) {
       if (array[i] == target) {
         return i;
@@ -126,7 +128,7 @@ public static boolean contains(byte[] array, byte target) {
    * @param target the array to search for as a sub-sequence of {@code array}
    */
   @SuppressWarnings("substringindex:return") // https://github.com/kelloggm/checker-framework/issues/206, 207 and 208
-  public static @LTEqLengthOf("#1") @SubstringIndexFor(value = "#1", offset = "#2.length - 1") int indexOf(byte[] array, byte[] target) {
+  public static @LTEqLengthOf("#1") @SubstringIndexFor(value = "#1", offset = "#2.length - 1") int indexOf(@PolySigned byte[] array, @PolySigned byte[] target) {
     checkNotNull(array, "array");
     checkNotNull(target, "target");
     if (target.length == 0) {
@@ -153,12 +155,12 @@ public static boolean contains(byte[] array, byte target) {
    * @return the greatest index {@code i} for which {@code array[i] == target}, or {@code -1} if no
    *     such index exists.
    */
-  public static @IndexOrLow("#1") int lastIndexOf(byte[] array, byte target) {
+  public static @IndexOrLow("#1") int lastIndexOf(@PolySigned byte[] array, @PolySigned byte target) {
     return lastIndexOf(array, target, 0, array.length);
   }
 
   // TODO(kevinb): consider making this public
-  private static @IndexOrLow("#1") @LessThan("#4") int lastIndexOf(byte[] array, byte target, @IndexOrHigh("#1") int start, @IndexOrHigh("#1") int end) {
+  private static @IndexOrLow("#1") @LessThan("#4") int lastIndexOf(@PolySigned byte[] array, @PolySigned byte target, @IndexOrHigh("#1") int start, @IndexOrHigh("#1") int end) {
     for (int i = end - 1; i >= start; i--) {
       if (array[i] == target) {
         return i;
@@ -181,7 +183,7 @@ public static boolean contains(byte[] array, byte target) {
    * range of length array.length in result.
    */
   @SuppressWarnings("upperbound:argument") // sum of lengths
-  public static byte[] concat(byte[]... arrays) {
+  public static @PolySigned byte[] concat(@PolySigned byte[]... arrays) {
     int length = 0;
     for (byte[] array : arrays) {
       length += array.length;
@@ -208,7 +210,7 @@ public static byte[] concat(byte[]... arrays) {
    * @return an array containing the values of {@code array}, with guaranteed minimum length {@code
    *     minLength}
    */
-  public static byte[] ensureCapacity(byte[] array, @NonNegative int minLength, @NonNegative int padding) {
+  public static @PolySigned byte[] ensureCapacity(@PolySigned byte[] array, @NonNegative int minLength, @NonNegative int padding) {
     checkArgument(minLength >= 0, "Invalid minLength: %s", minLength);
     checkArgument(padding >= 0, "Invalid padding: %s", padding);
     return (array.length < minLength) ? Arrays.copyOf(array, minLength + padding) : array;
@@ -227,7 +229,7 @@ public static byte[] ensureCapacity(byte[] array, @NonNegative int minLength, @N
    * @throws NullPointerException if {@code collection} or any of its elements is null
    * @since 1.0 (parameter was {@code Collection<Byte>} before 12.0)
    */
-  public static byte[] toArray(Collection<? extends Number> collection) {
+  public static <T extends Number> @PolySigned byte[] toArray(Collection<@PolySigned T> collection) {
     if (collection instanceof ByteArrayAsList) {
       return ((ByteArrayAsList) collection).toByteArray();
     }
@@ -254,13 +256,15 @@ public static byte[] toArray(Collection<? extends Number> collection) {
    * @param backingArray the array to back the list
    * @return a list view of the array
    */
-  public static List<Byte> asList(byte... backingArray) {
+  public static List<@PolySigned Byte> asList(@PolySigned byte... backingArray) {
     if (backingArray.length == 0) {
       return Collections.emptyList();
     }
     return new ByteArrayAsList(backingArray);
   }
 
+  @CFComment({"signedness: A non-generic container class permits only signed values.",
+              "Clients must suppress warnings when storing unsigned values."})
   @GwtCompatible
   private static class ByteArrayAsList extends AbstractList<Byte>
       implements RandomAccess, Serializable {
@@ -298,18 +302,18 @@ public Byte get(@IndexFor("this") int index) {
     }
 
     @Override
-    @SuppressWarnings("signedness:cast.unsafe")
+    @SuppressWarnings("signedness:cast.unsafe") // non-generic container class
     public boolean contains(@CheckForNull @UnknownSignedness Object target) {
       // Overridden to prevent a ton of boxing
-      return (target instanceof Byte) && Bytes.indexOf(array, (@Signed Byte) target, start, end) != -1;
+      return (target instanceof Byte) && Bytes.indexOf(array, (Byte) target, start, end) != -1;
     }
 
     @Override
-    @SuppressWarnings("signedness:cast.unsafe")
+    @SuppressWarnings("signedness:cast.unsafe") // non-generic container class
     public @IndexOrLow("this") int indexOf(@CheckForNull @UnknownSignedness Object target) {
       // Overridden to prevent a ton of boxing
       if (target instanceof Byte) {
-        int i = Bytes.indexOf(array, (@Signed Byte) target, start, end);
+        int i = Bytes.indexOf(array, (Byte) target, start, end);
         if (i >= 0) {
           return i - start;
         }
@@ -318,11 +322,11 @@ public boolean contains(@CheckForNull @UnknownSignedness Object target) {
     }
 
     @Override
-    @SuppressWarnings("signedness:cast.unsafe")
+    @SuppressWarnings("signedness:cast.unsafe") // non-generic container class
     public @IndexOrLow("this") int lastIndexOf(@CheckForNull @UnknownSignedness Object target) {
       // Overridden to prevent a ton of boxing
       if (target instanceof Byte) {
-        int i = Bytes.lastIndexOf(array, (@Signed Byte) target, start, end);
+        int i = Bytes.lastIndexOf(array, (Byte) target, start, end);
         if (i >= 0) {
           return i - start;
         }
diff --git a/guava/src/com/google/common/primitives/Chars.java b/guava/src/com/google/common/primitives/Chars.java
index 28462e915977..5f7e3fe5bba3 100644
--- a/guava/src/com/google/common/primitives/Chars.java
+++ b/guava/src/com/google/common/primitives/Chars.java
@@ -31,22 +31,25 @@
 import java.util.List;
 import java.util.RandomAccess;
 import javax.annotation.CheckForNull;
+import org.checkerframework.checker.index.qual.HasSubsequence;
 import org.checkerframework.checker.index.qual.IndexFor;
 import org.checkerframework.checker.index.qual.IndexOrHigh;
 import org.checkerframework.checker.index.qual.IndexOrLow;
 import org.checkerframework.checker.index.qual.LTEqLengthOf;
 import org.checkerframework.checker.index.qual.LTLengthOf;
+import org.checkerframework.checker.index.qual.LessThan;
 import org.checkerframework.checker.index.qual.NonNegative;
 import org.checkerframework.checker.index.qual.Positive;
 import org.checkerframework.checker.index.qual.SubstringIndexFor;
-import org.checkerframework.checker.index.qual.HasSubsequence;
-import org.checkerframework.checker.index.qual.LessThan;
 import org.checkerframework.checker.nullness.qual.Nullable;
 import org.checkerframework.checker.signedness.qual.Signed;
+import org.checkerframework.checker.signedness.qual.SignednessGlb;
 import org.checkerframework.checker.signedness.qual.UnknownSignedness;
+import org.checkerframework.checker.signedness.qual.Unsigned;
 import org.checkerframework.common.value.qual.IntRange;
 import org.checkerframework.common.value.qual.MinLen;
 import org.checkerframework.framework.qual.AnnotatedFor;
+import org.checkerframework.framework.qual.CFComment;
 
 /**
  * Static utility methods pertaining to {@code char} primitives, that are not already found in
@@ -319,9 +322,9 @@ public static char[] concat(char[]... arrays) {
    * use a shared {@link java.nio.ByteBuffer} instance, or use {@link
    * com.google.common.io.ByteStreams#newDataOutput()} to get a growable buffer.
    */
-  @SuppressWarnings("signedness:return")
+  @SuppressWarnings("signedness:return") // the bytes are bit patterns
   @GwtIncompatible // doesn't work
-  public static byte[] toByteArray(char value) {
+  public static @SignednessGlb byte[] toByteArray(char value) {
     return new byte[] {(byte) (value >> 8), (byte) value};
   }
 
@@ -347,9 +350,9 @@ public static char fromByteArray(byte @MinLen(Chars.BYTES)[] bytes) {
    *
    * @since 7.0
    */
-  @SuppressWarnings("signedness:cast.unsafe")
+  @SuppressWarnings("signedness:cast.unsafe") // the bytes are bit patterns
   @GwtIncompatible // doesn't work
-  public static char fromBytes(byte b1, byte b2) {
+  public static char fromBytes(@SignednessGlb byte b1, @SignednessGlb byte b2) {
     return (char) ((b1 << 8) | (b2 & 0xFF));
   }
 
@@ -452,8 +455,8 @@ public static char[] toArray(Collection<Character> collection) {
       return ((CharArrayAsList) collection).toCharArray();
     }
 
-    @SuppressWarnings("signedness:assignment")
-    Object[] boxedArray = collection.toArray();
+    @SuppressWarnings("signedness:assignment") // chars are always unsigned
+    @Unsigned Object[] boxedArray = collection.toArray();
     int len = boxedArray.length;
     char[] array = new char[len];
     for (int i = 0; i < len; i++) {
@@ -580,7 +583,6 @@ public boolean contains(@CheckForNull @UnknownSignedness Object target) {
     }
 
     @Override
-    @SuppressWarnings("lowerbound:return")
     public @IndexOrLow("this") int indexOf(@CheckForNull @UnknownSignedness Object target) {
       // Overridden to prevent a ton of boxing
       if (target instanceof Character) {
@@ -593,7 +595,6 @@ public boolean contains(@CheckForNull @UnknownSignedness Object target) {
     }
 
     @Override
-    @SuppressWarnings("lowerbound:return")
     public @IndexOrLow("this") int lastIndexOf(@CheckForNull @UnknownSignedness Object target) {
       // Overridden to prevent a ton of boxing
       if (target instanceof Character) {
diff --git a/guava/src/com/google/common/primitives/ImmutableIntArray.java b/guava/src/com/google/common/primitives/ImmutableIntArray.java
index 46b5a127e346..d6034f703fc1 100644
--- a/guava/src/com/google/common/primitives/ImmutableIntArray.java
+++ b/guava/src/com/google/common/primitives/ImmutableIntArray.java
@@ -37,19 +37,20 @@
 import org.checkerframework.checker.index.qual.EnsuresLTLengthOf;
 import org.checkerframework.checker.index.qual.EnsuresLTLengthOfIf;
 import org.checkerframework.checker.index.qual.GTENegativeOne;
+import org.checkerframework.checker.index.qual.HasSubsequence;
 import org.checkerframework.checker.index.qual.IndexFor;
 import org.checkerframework.checker.index.qual.IndexOrHigh;
 import org.checkerframework.checker.index.qual.IndexOrLow;
 import org.checkerframework.checker.index.qual.LTLengthOf;
+import org.checkerframework.checker.index.qual.LessThan;
 import org.checkerframework.checker.index.qual.NonNegative;
 import org.checkerframework.checker.index.qual.SameLen;
-import org.checkerframework.checker.index.qual.HasSubsequence;
-import org.checkerframework.checker.index.qual.LessThan;
 import org.checkerframework.checker.nullness.qual.Nullable;
 import org.checkerframework.checker.signedness.qual.Signed;
 import org.checkerframework.checker.signedness.qual.UnknownSignedness;
 import org.checkerframework.dataflow.qual.Pure;
 import org.checkerframework.framework.qual.AnnotatedFor;
+import org.checkerframework.framework.qual.CFComment;
 
 /**
  * An immutable array of {@code int} values, with an API resembling {@link List}.
@@ -521,6 +522,8 @@ public List<Integer> asList() {
     return new AsList(this);
   }
 
+  @CFComment({"signedness: A non-generic container class permits only signed values.",
+              "Clients must suppress warnings when storing unsigned values."})
   static class AsList extends AbstractList<Integer> implements RandomAccess, Serializable {
     private final @SameLen("this") ImmutableIntArray parent;
 
diff --git a/guava/src/com/google/common/primitives/ImmutableLongArray.java b/guava/src/com/google/common/primitives/ImmutableLongArray.java
index aca0b470dd8a..42ad0565ced4 100644
--- a/guava/src/com/google/common/primitives/ImmutableLongArray.java
+++ b/guava/src/com/google/common/primitives/ImmutableLongArray.java
@@ -37,19 +37,20 @@
 import org.checkerframework.checker.index.qual.EnsuresLTLengthOf;
 import org.checkerframework.checker.index.qual.EnsuresLTLengthOfIf;
 import org.checkerframework.checker.index.qual.GTENegativeOne;
+import org.checkerframework.checker.index.qual.HasSubsequence;
 import org.checkerframework.checker.index.qual.IndexFor;
 import org.checkerframework.checker.index.qual.IndexOrHigh;
 import org.checkerframework.checker.index.qual.IndexOrLow;
 import org.checkerframework.checker.index.qual.LTLengthOf;
+import org.checkerframework.checker.index.qual.LessThan;
 import org.checkerframework.checker.index.qual.NonNegative;
 import org.checkerframework.checker.index.qual.SameLen;
-import org.checkerframework.checker.index.qual.HasSubsequence;
-import org.checkerframework.checker.index.qual.LessThan;
 import org.checkerframework.checker.nullness.qual.Nullable;
 import org.checkerframework.checker.signedness.qual.Signed;
 import org.checkerframework.checker.signedness.qual.UnknownSignedness;
 import org.checkerframework.dataflow.qual.Pure;
 import org.checkerframework.framework.qual.AnnotatedFor;
+import org.checkerframework.framework.qual.CFComment;
 
 /**
  * An immutable array of {@code long} values, with an API resembling {@link List}.
@@ -523,6 +524,8 @@ public List<Long> asList() {
     return new AsList(this);
   }
 
+  @CFComment({"signedness: A non-generic container class permits only signed values.",
+              "Clients must suppress warnings when storing unsigned values."})
   static class AsList extends AbstractList<Long> implements RandomAccess, Serializable {
     private final @SameLen("this") ImmutableLongArray parent;
 
diff --git a/guava/src/com/google/common/primitives/Ints.java b/guava/src/com/google/common/primitives/Ints.java
index d20896f6d0b4..701873437bc7 100644
--- a/guava/src/com/google/common/primitives/Ints.java
+++ b/guava/src/com/google/common/primitives/Ints.java
@@ -34,23 +34,24 @@
 import java.util.Spliterator;
 import java.util.Spliterators;
 import javax.annotation.CheckForNull;
+import org.checkerframework.checker.index.qual.HasSubsequence;
 import org.checkerframework.checker.index.qual.IndexFor;
 import org.checkerframework.checker.index.qual.IndexOrHigh;
 import org.checkerframework.checker.index.qual.IndexOrLow;
 import org.checkerframework.checker.index.qual.LTEqLengthOf;
 import org.checkerframework.checker.index.qual.LTLengthOf;
+import org.checkerframework.checker.index.qual.LessThan;
 import org.checkerframework.checker.index.qual.NonNegative;
 import org.checkerframework.checker.index.qual.PolyLowerBound;
 import org.checkerframework.checker.index.qual.Positive;
 import org.checkerframework.checker.index.qual.SubstringIndexFor;
-import org.checkerframework.checker.index.qual.HasSubsequence;
-import org.checkerframework.checker.index.qual.LessThan;
 import org.checkerframework.checker.nullness.qual.Nullable;
 import org.checkerframework.checker.signedness.qual.Signed;
 import org.checkerframework.checker.signedness.qual.UnknownSignedness;
 import org.checkerframework.common.value.qual.IntRange;
 import org.checkerframework.common.value.qual.MinLen;
 import org.checkerframework.framework.qual.AnnotatedFor;
+import org.checkerframework.framework.qual.CFComment;
 
 /**
  * Static utility methods pertaining to {@code int} primitives, that are not already found in either
@@ -191,7 +192,6 @@ public static boolean contains(int[] array, int target) {
    * @param array the array to search for the sequence {@code target}
    * @param target the array to search for as a sub-sequence of {@code array}
    */
-  @SuppressWarnings("substringindex:return")
   public static @LTEqLengthOf("#1") @SubstringIndexFor(value = "#1", offset="#2.length - 1") int indexOf(int[] array, int[] target) {
     checkNotNull(array, "array");
     checkNotNull(target, "target");
@@ -588,6 +588,8 @@ public static List<Integer> asList(int... backingArray) {
     return new IntArrayAsList(backingArray);
   }
 
+  @CFComment({"signedness: A non-generic container class permits only signed values.",
+              "Clients must suppress warnings when storing unsigned values."})
   @GwtCompatible
   private static class IntArrayAsList extends AbstractList<Integer>
       implements RandomAccess, Serializable {
@@ -636,7 +638,7 @@ public boolean contains(@CheckForNull @UnknownSignedness Object target) {
     }
 
     @Override
-    @SuppressWarnings("signedness:cast.unsafe")
+    @SuppressWarnings("signedness:cast.unsafe") // non-generic container class
     public @IndexOrLow("this") int indexOf(@CheckForNull @UnknownSignedness Object target) {
       // Overridden to prevent a ton of boxing
       if (target instanceof Integer) {
@@ -649,7 +651,7 @@ public boolean contains(@CheckForNull @UnknownSignedness Object target) {
     }
 
     @Override
-    @SuppressWarnings("signedness:cast.unsafe")
+    @SuppressWarnings("signedness:cast.unsafe") // non-generic container class
     public @IndexOrLow("this")int lastIndexOf(@CheckForNull @UnknownSignedness Object target) {
       // Overridden to prevent a ton of boxing
       if (target instanceof Integer) {
diff --git a/guava/src/com/google/common/primitives/Longs.java b/guava/src/com/google/common/primitives/Longs.java
index 66f440e98d0d..af6699bd81b3 100644
--- a/guava/src/com/google/common/primitives/Longs.java
+++ b/guava/src/com/google/common/primitives/Longs.java
@@ -33,22 +33,23 @@
 import java.util.Spliterator;
 import java.util.Spliterators;
 import javax.annotation.CheckForNull;
+import org.checkerframework.checker.index.qual.HasSubsequence;
 import org.checkerframework.checker.index.qual.IndexFor;
 import org.checkerframework.checker.index.qual.IndexOrHigh;
 import org.checkerframework.checker.index.qual.IndexOrLow;
 import org.checkerframework.checker.index.qual.LTEqLengthOf;
 import org.checkerframework.checker.index.qual.LTLengthOf;
+import org.checkerframework.checker.index.qual.LessThan;
 import org.checkerframework.checker.index.qual.NonNegative;
 import org.checkerframework.checker.index.qual.Positive;
 import org.checkerframework.checker.index.qual.SubstringIndexFor;
-import org.checkerframework.checker.index.qual.HasSubsequence;
-import org.checkerframework.checker.index.qual.LessThan;
+import org.checkerframework.checker.nullness.qual.Nullable;
 import org.checkerframework.checker.signedness.qual.Signed;
 import org.checkerframework.checker.signedness.qual.UnknownSignedness;
-import org.checkerframework.checker.nullness.qual.Nullable;
 import org.checkerframework.common.value.qual.IntRange;
 import org.checkerframework.common.value.qual.MinLen;
 import org.checkerframework.framework.qual.AnnotatedFor;
+import org.checkerframework.framework.qual.CFComment;
 
 /**
  * Static utility methods pertaining to {@code long} primitives, that are not already found in
@@ -162,7 +163,6 @@ public static boolean contains(long[] array, long target) {
    * @param array the array to search for the sequence {@code target}
    * @param target the array to search for as a sub-sequence of {@code array}
    */
-  @SuppressWarnings("substringindex:return")
   public static @LTEqLengthOf("#1") @SubstringIndexFor(value = "#1", offset="#2.length - 1") int indexOf(long[] array, long[] target) {
     checkNotNull(array, "array");
     checkNotNull(target, "target");
@@ -686,6 +686,8 @@ public static List<Long> asList(long... backingArray) {
     return new LongArrayAsList(backingArray);
   }
 
+  @CFComment({"signedness: A non-generic container class permits only signed values.",
+              "Clients must suppress warnings when storing unsigned values."})
   @GwtCompatible
   private static class LongArrayAsList extends AbstractList<Long>
       implements RandomAccess, Serializable {
@@ -728,14 +730,14 @@ public Spliterator.OfLong spliterator() {
     }
 
     @Override
-    @SuppressWarnings("signedness:cast.unsafe")
+    @SuppressWarnings("signedness:cast.unsafe") // non-generic container class
     public boolean contains(@CheckForNull @UnknownSignedness Object target) {
       // Overridden to prevent a ton of boxing
       return (target instanceof Long) && Longs.indexOf(array, (@Signed Long) target, start, end) != -1;
     }
 
     @Override
-    @SuppressWarnings("signedness:cast.unsafe")
+    @SuppressWarnings("signedness:cast.unsafe") // non-generic container class
     public @IndexOrLow("this") int indexOf(@CheckForNull @UnknownSignedness Object target) {
       // Overridden to prevent a ton of boxing
       if (target instanceof Long) {
@@ -748,7 +750,7 @@ public boolean contains(@CheckForNull @UnknownSignedness Object target) {
     }
 
     @Override
-    @SuppressWarnings("signedness:cast.unsafe")
+    @SuppressWarnings("signedness:cast.unsafe") // non-generic container class
     public @IndexOrLow("this") int lastIndexOf(@CheckForNull @UnknownSignedness Object target) {
       // Overridden to prevent a ton of boxing
       if (target instanceof Long) {
diff --git a/guava/src/com/google/common/primitives/Shorts.java b/guava/src/com/google/common/primitives/Shorts.java
index 20218988ce2b..44368c1bab60 100644
--- a/guava/src/com/google/common/primitives/Shorts.java
+++ b/guava/src/com/google/common/primitives/Shorts.java
@@ -32,22 +32,23 @@
 import java.util.List;
 import java.util.RandomAccess;
 import javax.annotation.CheckForNull;
+import org.checkerframework.checker.index.qual.HasSubsequence;
 import org.checkerframework.checker.index.qual.IndexFor;
 import org.checkerframework.checker.index.qual.IndexOrHigh;
 import org.checkerframework.checker.index.qual.IndexOrLow;
 import org.checkerframework.checker.index.qual.LTEqLengthOf;
 import org.checkerframework.checker.index.qual.LTLengthOf;
+import org.checkerframework.checker.index.qual.LessThan;
 import org.checkerframework.checker.index.qual.NonNegative;
 import org.checkerframework.checker.index.qual.Positive;
 import org.checkerframework.checker.index.qual.SubstringIndexFor;
-import org.checkerframework.checker.index.qual.HasSubsequence;
-import org.checkerframework.checker.index.qual.LessThan;
 import org.checkerframework.checker.nullness.qual.Nullable;
 import org.checkerframework.checker.signedness.qual.Signed;
 import org.checkerframework.checker.signedness.qual.UnknownSignedness;
 import org.checkerframework.common.value.qual.IntRange;
 import org.checkerframework.common.value.qual.MinLen;
 import org.checkerframework.framework.qual.AnnotatedFor;
+import org.checkerframework.framework.qual.CFComment;
 
 /**
  * Static utility methods pertaining to {@code short} primitives, that are not already found in
@@ -584,6 +585,8 @@ public static List<Short> asList(short... backingArray) {
     return new ShortArrayAsList(backingArray);
   }
 
+  @CFComment({"signedness: A non-generic container class permits only signed values.",
+              "Clients must suppress warnings when storing unsigned values."})
   @GwtCompatible
   private static class ShortArrayAsList extends AbstractList<Short>
       implements RandomAccess, Serializable {
@@ -621,7 +624,7 @@ public Short get(@IndexFor("this") int index) {
     }
 
     @Override
-    @SuppressWarnings("signedness:cast.unsafe")
+    @SuppressWarnings("signedness:cast.unsafe") // non-generic container class
     public boolean contains(@CheckForNull @UnknownSignedness Object target) {
       // Overridden to prevent a ton of boxing
       return (target instanceof Short) && Shorts.indexOf(array, (@Signed Short) target, start, end) != -1;
@@ -629,7 +632,7 @@ public boolean contains(@CheckForNull @UnknownSignedness Object target) {
 
 
     @Override
-    @SuppressWarnings("signedness:cast.unsafe")
+    @SuppressWarnings("signedness:cast.unsafe") // non-generic container class
     public @IndexOrLow("this") int indexOf(@CheckForNull @UnknownSignedness Object target) {
       // Overridden to prevent a ton of boxing
       if (target instanceof Short) {
@@ -642,7 +645,7 @@ public boolean contains(@CheckForNull @UnknownSignedness Object target) {
     }
 
     @Override
-    @SuppressWarnings("signedness:cast.unsafe")
+    @SuppressWarnings("signedness:cast.unsafe") // non-generic container class
     public @IndexOrLow("this") int lastIndexOf(@CheckForNull @UnknownSignedness Object target) {
       // Overridden to prevent a ton of boxing
       if (target instanceof Short) {
diff --git a/guava/src/com/google/common/primitives/UnsignedBytes.java b/guava/src/com/google/common/primitives/UnsignedBytes.java
index 71e19885841f..ef7d0d977bf0 100644
--- a/guava/src/com/google/common/primitives/UnsignedBytes.java
+++ b/guava/src/com/google/common/primitives/UnsignedBytes.java
@@ -232,14 +232,14 @@ public static String toString(@Unsigned byte x, @IntRange(from=2, to=36) int rad
    *     Byte#parseByte(String)})
    * @since 13.0
    */
-  @SuppressWarnings("signedness:return")
+  @SuppressWarnings("signedness:cast") // if statement guarantees all is ok
   @Beta
   @CanIgnoreReturnValue
   public static @Unsigned byte parseUnsignedByte(String string, @IntRange(from=2, to=36) int radix) {
     int parse = Integer.parseInt(checkNotNull(string), radix);
     // We need to throw a NumberFormatException, so we have to duplicate checkedCast. =(
     if (parse >> Byte.SIZE == 0) {
-      return (byte) parse;
+      return (@Unsigned byte) parse;
     } else {
       throw new NumberFormatException("out of range: " + parse);
     }
@@ -379,9 +379,8 @@ public sun.misc.Unsafe run() throws Exception {
 
       @Override
       @SuppressWarnings({
-        "signedness:argument",
-        "signedness:return",
-        "signedness:shift.unsigned"
+        "signedness:argument",       // getLong guarantees lw and rw are ok
+        "signedness:shift.unsigned"  // doing tricky math with shifts
       })
       public int compare(@Unsigned byte[] left, @Unsigned byte[] right) {
         int stride = 8;
@@ -476,9 +475,9 @@ public String toString() {
     }
   }
 
-  @SuppressWarnings("signedness:return")
+  //@SuppressWarnings("signedness:return") // https://github.com/typetools/checker-framework/issues/5773
   private static @PolySigned byte flip(@PolySigned byte b) {
-    return (byte) (b ^ 0x80);
+    return (@PolySigned byte) (b ^ 0x80);
   }
 
   /**
@@ -497,7 +496,7 @@ public static void sort(@Unsigned byte[] array) {
    *
    * @since 23.1
    */
-  @SuppressWarnings("signedness:argument")
+  @SuppressWarnings("signedness:argument") // sorting byte-flipped values
   public static void sort(@Unsigned byte[] array, @IndexOrHigh("#1") int fromIndex, @IndexOrHigh("#1") int toIndex) {
     checkNotNull(array);
     checkPositionIndexes(fromIndex, toIndex, array.length);
@@ -527,7 +526,7 @@ public static void sortDescending(@Unsigned byte[] array) {
    *
    * @since 23.1
    */
-  @SuppressWarnings("signedness:argument")
+  @SuppressWarnings("signedness:argument") // sorting byte-flipped values
   public static void sortDescending(@Unsigned byte[] array, @IndexOrHigh("#1") int fromIndex, @IndexOrHigh("#1") int toIndex) {
     checkNotNull(array);
     checkPositionIndexes(fromIndex, toIndex, array.length);
diff --git a/guava/src/com/google/common/primitives/UnsignedInteger.java b/guava/src/com/google/common/primitives/UnsignedInteger.java
index 29a7095e2a2c..ab608301b7e1 100644
--- a/guava/src/com/google/common/primitives/UnsignedInteger.java
+++ b/guava/src/com/google/common/primitives/UnsignedInteger.java
@@ -27,6 +27,7 @@
 import org.checkerframework.checker.index.qual.NonNegative;
 import org.checkerframework.checker.index.qual.Positive;
 import org.checkerframework.checker.nullness.qual.Nullable;
+import org.checkerframework.checker.signedness.qual.UnknownSignedness;
 import org.checkerframework.common.value.qual.IntRange;
 import org.checkerframework.common.value.qual.PolyValue;
 import org.checkerframework.framework.qual.AnnotatedFor;
@@ -71,7 +72,7 @@ private UnsignedInteger(int value) {
    *
    * @since 14.0
    */
-  public static UnsignedInteger fromIntBits(int bits) {
+  public static UnsignedInteger fromIntBits(@UnknownSignedness int bits) {
     return new UnsignedInteger(bits);
   }
 
@@ -120,7 +121,7 @@ public static UnsignedInteger valueOf(String string) {
    * @throws NumberFormatException if the string does not contain a parsable unsigned {@code int}
    *     value
    */
-  @SuppressWarnings("signedness:argument")
+  @SuppressWarnings("signedness:argument") // parseUnsignedInt guarantees value fits in int
   public static UnsignedInteger valueOf(String string, @IntRange(from=2, to=36) int radix) {
     return fromIntBits(UnsignedInts.parseUnsignedInt(string, radix));
   }
@@ -163,7 +164,7 @@ public UnsignedInteger times(UnsignedInteger val) {
    * @throws ArithmeticException if {@code val} is zero
    * @since 14.0
    */
-  @SuppressWarnings("signedness:argument")
+  @SuppressWarnings("signedness:argument") // 'divide' guarantees result fits in int
   public UnsignedInteger dividedBy(UnsignedInteger val) {
     return fromIntBits(UnsignedInts.divide(value, checkNotNull(val).value));
   }
@@ -174,7 +175,7 @@ public UnsignedInteger dividedBy(UnsignedInteger val) {
    * @throws ArithmeticException if {@code val} is zero
    * @since 14.0
    */
-  @SuppressWarnings("signedness:argument")
+  @SuppressWarnings("signedness:argument") // 'remainder' guarantees result fits in int
   public UnsignedInteger mod(UnsignedInteger val) {
     return fromIntBits(UnsignedInts.remainder(value, checkNotNull(val).value));
   }
@@ -187,14 +188,14 @@ public UnsignedInteger mod(UnsignedInteger val) {
    * will be equal to {@code this - 2^32}.
    */
   @Override
-  @SuppressWarnings("cast.unsafe")
+  @SuppressWarnings("value:cast.unsafe") // Unknown int to PolyValue int is ok
   public @PolyValue int intValue(@PolyValue UnsignedInteger this) {
     return (@PolyValue int) value;
   }
 
   /** Returns the value of this {@code UnsignedInteger} as a {@code long}. */
   @Override
-  @SuppressWarnings("cast.unsafe")
+  @SuppressWarnings("value:cast.unsafe") // Unknown long to PolyValue long is ok
   public @PolyValue long longValue(@PolyValue UnsignedInteger this) {
     return (@PolyValue long) toLong(value);
   }
@@ -204,7 +205,6 @@ public UnsignedInteger mod(UnsignedInteger val) {
    * primitive conversion from {@code int} to {@code float}, and correctly rounded.
    */
   @Override
-  @SuppressWarnings("cast.unsafe")
   public @PolyValue float floatValue(@PolyValue UnsignedInteger this) {
     return longValue();
   }
@@ -229,7 +229,7 @@ public BigInteger bigIntegerValue() {
    * other}.
    */
   @Override
-  @SuppressWarnings("signedness:argument")
+  @SuppressWarnings("signedness:argument") // value(s) are actually unsigned
   public int compareTo(UnsignedInteger other) {
     checkNotNull(other);
     return compare(value, other.value);
@@ -260,7 +260,7 @@ public String toString() {
    * {@code radix < Character.MIN_RADIX} or {@code radix > Character.MAX_RADIX}, the radix {@code
    * 10} is used.
    */
-  @SuppressWarnings("signedness:argument")
+  @SuppressWarnings("signedness:argument") // value is actually unsigned
   public String toString(@IntRange(from=2, to=36) int radix) {
     return UnsignedInts.toString(value, radix);
   }
diff --git a/guava/src/com/google/common/primitives/UnsignedInts.java b/guava/src/com/google/common/primitives/UnsignedInts.java
index eed54ad34d51..95faca193b2b 100644
--- a/guava/src/com/google/common/primitives/UnsignedInts.java
+++ b/guava/src/com/google/common/primitives/UnsignedInts.java
@@ -106,9 +106,10 @@ public static int compare(@Unsigned int a, @Unsigned int b) {
    */
   // "(long value)" was originally "(@IntRange(from = 0, to = (2L << 32) - 1) long value)"
   // but that caused too many checker warnings.
+  @SuppressWarnings("signedness:cast.unsafe") // checkArgument guarantees value fits in Unsigned int
   public static @Unsigned int checkedCast(long value) {
     checkArgument((value >> Integer.SIZE) == 0, "out of range: %s", value);
-    return (int) value;
+    return (@Unsigned int) value;
   }
 
   /**
@@ -275,7 +276,7 @@ public static void sortDescending(@Unsigned int[] array) {
    *
    * @since 23.1
    */
-  @SuppressWarnings("signedness:argument")
+  @SuppressWarnings("signedness:argument") // sorting bit-flipped values
   public static void sortDescending(@Unsigned int[] array, @IndexOrHigh("#1") int fromIndex, @IndexOrHigh("#1") int toIndex) {
     checkNotNull(array);
     checkPositionIndexes(fromIndex, toIndex, array.length);
diff --git a/guava/src/com/google/common/primitives/UnsignedLongs.java b/guava/src/com/google/common/primitives/UnsignedLongs.java
index 579da3f08314..296567390189 100644
--- a/guava/src/com/google/common/primitives/UnsignedLongs.java
+++ b/guava/src/com/google/common/primitives/UnsignedLongs.java
@@ -69,7 +69,7 @@ private UnsignedLongs() {}
    * longs, that is, {@code a <= b} as unsigned longs if and only if {@code flip(a) <= flip(b)} as
    * signed longs.
    */
-  @SuppressWarnings("signedness:return")
+  @SuppressWarnings("signedness:return") // https://github.com/typetools/checker-framework/issues/5773
   private static @PolySigned long flip(@PolySigned long a) {
     return a ^ Long.MIN_VALUE;
   }
@@ -85,7 +85,7 @@ private UnsignedLongs() {}
    * @return a negative value if {@code a} is less than {@code b}; a positive value if {@code a} is
    *     greater than {@code b}; or zero if they are equal
    */
-  @SuppressWarnings("signedness:argument")
+  @SuppressWarnings("signedness:argument") // comparison of bit-flipped values
   public static int compare(@Unsigned long a, @Unsigned long b) {
     return Longs.compare(flip(a), flip(b));
   }
@@ -98,7 +98,7 @@ public static int compare(@Unsigned long a, @Unsigned long b) {
    *     the array according to {@link #compare}
    * @throws IllegalArgumentException if {@code array} is empty
    */
-  @SuppressWarnings("signedness:comparison")
+  @SuppressWarnings("signedness:comparison.unsignedlhs") // comparison of bit-flipped values
   public static @Unsigned long min(@Unsigned long @MinLen(1)... array) {
     checkArgument(array.length > 0);
     long min = flip(array[0]);
@@ -119,7 +119,7 @@ public static int compare(@Unsigned long a, @Unsigned long b) {
    *     in the array according to {@link #compare}
    * @throws IllegalArgumentException if {@code array} is empty
    */
-  @SuppressWarnings("signedness:comparison")
+  @SuppressWarnings("signedness:comparison.unsignedlhs") // comparison of bit-flipped values
   public static @Unsigned long max(@Unsigned long @MinLen(1)... array) {
     checkArgument(array.length > 0);
     long max = flip(array[0]);
@@ -206,7 +206,7 @@ public static void sort(@Unsigned long[] array) {
    *
    * @since 23.1
    */
-  @SuppressWarnings("signedness:argument")
+  @SuppressWarnings("signedness:argument") // sorting bit-flipped values
   public static void sort(@Unsigned long[] array, @IndexOrHigh("#1") int fromIndex, @IndexOrHigh("#1") int toIndex) {
     checkNotNull(array);
     checkPositionIndexes(fromIndex, toIndex, array.length);
@@ -236,7 +236,7 @@ public static void sortDescending(@Unsigned long[] array) {
    *
    * @since 23.1
    */
-  @SuppressWarnings("signedness:argument")
+  @SuppressWarnings("signedness:argument") // sorting bit-flipped values
   public static void sortDescending(@Unsigned long[] array, @IndexOrHigh("#1") int fromIndex, @IndexOrHigh("#1") int toIndex) {
     checkNotNull(array);
     checkPositionIndexes(fromIndex, toIndex, array.length);
@@ -259,7 +259,7 @@ public static void sortDescending(@Unsigned long[] array, @IndexOrHigh("#1") int
    * @param divisor the divisor (denominator)
    * @throws ArithmeticException if divisor is 0
    */
-  @SuppressWarnings("signedness:comparison")
+  @SuppressWarnings("signedness:comparison.unsignedlhs") // testing for large unsigned values
   public static @Unsigned long divide(@Unsigned long dividend, @Unsigned long divisor) {
     if (divisor < 0) { // i.e., divisor >= 2^63:
       if (compare(dividend, divisor) < 0) {
@@ -280,7 +280,7 @@ public static void sortDescending(@Unsigned long[] array, @IndexOrHigh("#1") int
      * floor(floor(x)/i) == floor(x/i) for any real x and integer i != 0. The proof is not quite
      * trivial.
      */
-    @SuppressWarnings("signedness:operation")
+    @SuppressWarnings("signedness:operation.unsignedlhs") // '>>> 1' guarantees divide ok
     long quotient = ((dividend >>> 1) / divisor) << 1;
     long rem = dividend - quotient * divisor;
     return quotient + (compare(rem, divisor) >= 0 ? 1 : 0);
@@ -297,7 +297,7 @@ public static void sortDescending(@Unsigned long[] array, @IndexOrHigh("#1") int
    * @throws ArithmeticException if divisor is 0
    * @since 11.0
    */
-  @SuppressWarnings("signedness:comparison")
+  @SuppressWarnings("signedness:comparison.unsignedlhs") // testing for large unsigned values
   public static @Unsigned long remainder(@Unsigned long dividend, @Unsigned long divisor) {
     if (divisor < 0) { // i.e., divisor >= 2^63:
       if (compare(dividend, divisor) < 0) {
@@ -318,7 +318,7 @@ public static void sortDescending(@Unsigned long[] array, @IndexOrHigh("#1") int
      * that floor(floor(x)/i) == floor(x/i) for any real x and integer i != 0. The proof is not
      * quite trivial.
      */
-    @SuppressWarnings("signedness:operation")
+    @SuppressWarnings("signedness:operation.unsignedlhs") // '>>> 1' guarantees divide ok
     long quotient = ((dividend >>> 1) / divisor) << 1;
     long rem = dividend - quotient * divisor;
     return rem - (compare(rem, divisor) >= 0 ? divisor : 0);

From 82031ab79e147f6123bacea1051489d8ffe1699f Mon Sep 17 00:00:00 2001
From: Michael Ernst <mernst@cs.washington.edu>
Date: Sun, 14 May 2023 10:43:49 -0700
Subject: [PATCH 13/21] Avoid long lines

---
 guava/src/com/google/common/primitives/Booleans.java     | 5 ++++-
 guava/src/com/google/common/primitives/Bytes.java        | 5 ++++-
 guava/src/com/google/common/primitives/Chars.java        | 5 ++++-
 guava/src/com/google/common/primitives/Doubles.java      | 9 ++++++---
 guava/src/com/google/common/primitives/Floats.java       | 9 ++++++---
 .../google/common/primitives/ImmutableDoubleArray.java   | 9 ++++++---
 .../com/google/common/primitives/ImmutableIntArray.java  | 5 ++++-
 .../com/google/common/primitives/ImmutableLongArray.java | 5 ++++-
 guava/src/com/google/common/primitives/Ints.java         | 5 +++++
 guava/src/com/google/common/primitives/Longs.java        | 5 ++++-
 guava/src/com/google/common/primitives/Shorts.java       | 5 ++++-
 11 files changed, 51 insertions(+), 16 deletions(-)

diff --git a/guava/src/com/google/common/primitives/Booleans.java b/guava/src/com/google/common/primitives/Booleans.java
index 4f00141fbe52..2f16b2414d9f 100644
--- a/guava/src/com/google/common/primitives/Booleans.java
+++ b/guava/src/com/google/common/primitives/Booleans.java
@@ -412,7 +412,10 @@ private static class BooleanArrayAsList extends AbstractList<Boolean>
     }
 
     @SuppressWarnings(
-            "index") // these three fields need to be initialized in some order, and any ordering leads to the first two issuing errors - since each field is dependent on at least one of the others
+        "index" // these three fields need to be initialized in some order, and any ordering
+    // leads to the first two issuing errors - since each field is dependent on
+    // at least one of the others
+    )
     BooleanArrayAsList(boolean @MinLen(1)[] array, @IndexFor("#1") @LessThan("#3") int start, @IndexOrHigh("#1") int end) {
       this.array = array;
       this.start = start;
diff --git a/guava/src/com/google/common/primitives/Bytes.java b/guava/src/com/google/common/primitives/Bytes.java
index 1db3e9f36500..833297e7ddcf 100644
--- a/guava/src/com/google/common/primitives/Bytes.java
+++ b/guava/src/com/google/common/primitives/Bytes.java
@@ -278,7 +278,10 @@ private static class ByteArrayAsList extends AbstractList<Byte>
     }
 
     @SuppressWarnings(
-            "index") // these three fields need to be initialized in some order, and any ordering leads to the first two issuing errors - since each field is dependent on at least one of the others
+        "index" // these three fields need to be initialized in some order, and any ordering
+    // leads to the first two issuing errors - since each field is dependent on
+    // at least one of the others
+    )
     ByteArrayAsList(byte @MinLen(1)[] array, @IndexFor("#1") @LessThan("#3") int start, @IndexOrHigh("#1") int end) {
       this.array = array;
       this.start = start;
diff --git a/guava/src/com/google/common/primitives/Chars.java b/guava/src/com/google/common/primitives/Chars.java
index 5f7e3fe5bba3..d1f1f412be3f 100644
--- a/guava/src/com/google/common/primitives/Chars.java
+++ b/guava/src/com/google/common/primitives/Chars.java
@@ -552,7 +552,10 @@ private static class CharArrayAsList extends AbstractList<Character>
     }
 
     @SuppressWarnings(
-            "index") // these three fields need to be initialized in some order, and any ordering leads to the first two issuing errors - since each field is dependent on at least one of the others
+        "index" // these three fields need to be initialized in some order, and any ordering
+    // leads to the first two issuing errors - since each field is dependent on
+    // at least one of the others
+    )
     CharArrayAsList(char @MinLen(1)[] array, @IndexFor("#1") @LessThan("#3") int start, @IndexOrHigh("#1") int end) {
       this.array = array;
       this.start = start;
diff --git a/guava/src/com/google/common/primitives/Doubles.java b/guava/src/com/google/common/primitives/Doubles.java
index c4d7c5581a4d..e0b020ae1dc5 100644
--- a/guava/src/com/google/common/primitives/Doubles.java
+++ b/guava/src/com/google/common/primitives/Doubles.java
@@ -37,16 +37,16 @@
 import java.util.Spliterator;
 import java.util.Spliterators;
 import javax.annotation.CheckForNull;
+import org.checkerframework.checker.index.qual.HasSubsequence;
 import org.checkerframework.checker.index.qual.IndexFor;
 import org.checkerframework.checker.index.qual.IndexOrHigh;
 import org.checkerframework.checker.index.qual.IndexOrLow;
 import org.checkerframework.checker.index.qual.LTEqLengthOf;
 import org.checkerframework.checker.index.qual.LTLengthOf;
+import org.checkerframework.checker.index.qual.LessThan;
 import org.checkerframework.checker.index.qual.NonNegative;
 import org.checkerframework.checker.index.qual.Positive;
 import org.checkerframework.checker.index.qual.SubstringIndexFor;
-import org.checkerframework.checker.index.qual.HasSubsequence;
-import org.checkerframework.checker.index.qual.LessThan;
 import org.checkerframework.checker.nullness.qual.Nullable;
 import org.checkerframework.checker.signedness.qual.Signed;
 import org.checkerframework.checker.signedness.qual.UnknownSignedness;
@@ -559,7 +559,10 @@ private static class DoubleArrayAsList extends AbstractList<Double>
     }
 
     @SuppressWarnings(
-            "index") // these three fields need to be initialized in some order, and any ordering leads to the first two issuing errors - since each field is dependent on at least one of the others
+        "index" // these three fields need to be initialized in some order, and any ordering
+    // leads to the first two issuing errors - since each field is dependent on
+    // at least one of the others
+    )
     DoubleArrayAsList(double @MinLen(1)[] array, @IndexFor("#1") @LessThan("#3") int start, @IndexOrHigh("#1") int end) {
       this.array = array;
       this.start = start;
diff --git a/guava/src/com/google/common/primitives/Floats.java b/guava/src/com/google/common/primitives/Floats.java
index 2bcd0a84b963..c9c4a301f653 100644
--- a/guava/src/com/google/common/primitives/Floats.java
+++ b/guava/src/com/google/common/primitives/Floats.java
@@ -35,16 +35,16 @@
 import java.util.List;
 import java.util.RandomAccess;
 import javax.annotation.CheckForNull;
+import org.checkerframework.checker.index.qual.HasSubsequence;
 import org.checkerframework.checker.index.qual.IndexFor;
 import org.checkerframework.checker.index.qual.IndexOrHigh;
 import org.checkerframework.checker.index.qual.IndexOrLow;
 import org.checkerframework.checker.index.qual.LTEqLengthOf;
 import org.checkerframework.checker.index.qual.LTLengthOf;
+import org.checkerframework.checker.index.qual.LessThan;
 import org.checkerframework.checker.index.qual.NonNegative;
 import org.checkerframework.checker.index.qual.Positive;
 import org.checkerframework.checker.index.qual.SubstringIndexFor;
-import org.checkerframework.checker.index.qual.HasSubsequence;
-import org.checkerframework.checker.index.qual.LessThan;
 import org.checkerframework.checker.nullness.qual.Nullable;
 import org.checkerframework.checker.signedness.qual.Signed;
 import org.checkerframework.checker.signedness.qual.UnknownSignedness;
@@ -551,7 +551,10 @@ private static class FloatArrayAsList extends AbstractList<Float>
     }
 
     @SuppressWarnings(
-            "index") // these three fields need to be initialized in some order, and any ordering leads to the first two issuing errors - since each field is dependent on at least one of the others
+        "index" // these three fields need to be initialized in some order, and any ordering
+    // leads to the first two issuing errors - since each field is dependent on
+    // at least one of the others
+    )
     FloatArrayAsList(float @MinLen(1)[] array, @IndexFor("#1") @LessThan("#3") int start, @IndexOrHigh("#1") int end) {
       this.array = array;
       this.start = start;
diff --git a/guava/src/com/google/common/primitives/ImmutableDoubleArray.java b/guava/src/com/google/common/primitives/ImmutableDoubleArray.java
index 62437e86230a..9d138bbf0a2b 100644
--- a/guava/src/com/google/common/primitives/ImmutableDoubleArray.java
+++ b/guava/src/com/google/common/primitives/ImmutableDoubleArray.java
@@ -37,14 +37,14 @@
 import org.checkerframework.checker.index.qual.EnsuresLTLengthOf;
 import org.checkerframework.checker.index.qual.EnsuresLTLengthOfIf;
 import org.checkerframework.checker.index.qual.GTENegativeOne;
+import org.checkerframework.checker.index.qual.HasSubsequence;
 import org.checkerframework.checker.index.qual.IndexFor;
 import org.checkerframework.checker.index.qual.IndexOrHigh;
 import org.checkerframework.checker.index.qual.IndexOrLow;
 import org.checkerframework.checker.index.qual.LTLengthOf;
+import org.checkerframework.checker.index.qual.LessThan;
 import org.checkerframework.checker.index.qual.NonNegative;
 import org.checkerframework.checker.index.qual.SameLen;
-import org.checkerframework.checker.index.qual.HasSubsequence;
-import org.checkerframework.checker.index.qual.LessThan;
 import org.checkerframework.checker.nullness.qual.Nullable;
 import org.checkerframework.checker.signedness.qual.Signed;
 import org.checkerframework.checker.signedness.qual.UnknownSignedness;
@@ -399,7 +399,10 @@ private ImmutableDoubleArray(double[] array) {
   }
 
   @SuppressWarnings(
-          "index") // these three fields need to be initialized in some order, and any ordering leads to the first two issuing errors - since each field is dependent on at least one of the others
+      "index" // these three fields need to be initialized in some order, and any ordering
+  // leads to the first two issuing errors - since each field is dependent on
+  // at least one of the others
+  )
   private ImmutableDoubleArray(double[] array, @IndexOrHigh("#1") @LessThan("#3 + 1") int start, @IndexOrHigh("#1") int end) {
     this.array = array;
     this.start = start;
diff --git a/guava/src/com/google/common/primitives/ImmutableIntArray.java b/guava/src/com/google/common/primitives/ImmutableIntArray.java
index d6034f703fc1..68ae29933350 100644
--- a/guava/src/com/google/common/primitives/ImmutableIntArray.java
+++ b/guava/src/com/google/common/primitives/ImmutableIntArray.java
@@ -397,7 +397,10 @@ private ImmutableIntArray(int[] array) {
   }
 
   @SuppressWarnings(
-          "index") // these three fields need to be initialized in some order, and any ordering leads to the first two issuing errors - since each field is dependent on at least one of the others
+      "index" // these three fields need to be initialized in some order, and any ordering
+  // leads to the first two issuing errors - since each field is dependent on
+  // at least one of the others
+  )
   private ImmutableIntArray(int[] array, @IndexOrHigh("#1") @LessThan("#3 + 1") int start, @IndexOrHigh("#1") int end) {
     this.array = array;
     this.start = start;
diff --git a/guava/src/com/google/common/primitives/ImmutableLongArray.java b/guava/src/com/google/common/primitives/ImmutableLongArray.java
index 42ad0565ced4..5612c751340b 100644
--- a/guava/src/com/google/common/primitives/ImmutableLongArray.java
+++ b/guava/src/com/google/common/primitives/ImmutableLongArray.java
@@ -399,7 +399,10 @@ private ImmutableLongArray(long[] array) {
   }
 
   @SuppressWarnings(
-          "index") // these three fields need to be initialized in some order, and any ordering leads to the first two issuing errors - since each field is dependent on at least one of the others
+      "index" // these three fields need to be initialized in some order, and any ordering
+  // leads to the first two issuing errors - since each field is dependent on
+  // at least one of the others
+  )
   private ImmutableLongArray(long[] array, @IndexOrHigh("#1") int start, @IndexOrHigh("#1") int end) {
     this.array = array;
     this.start = start;
diff --git a/guava/src/com/google/common/primitives/Ints.java b/guava/src/com/google/common/primitives/Ints.java
index 701873437bc7..683e4f47300e 100644
--- a/guava/src/com/google/common/primitives/Ints.java
+++ b/guava/src/com/google/common/primitives/Ints.java
@@ -602,6 +602,11 @@ private static class IntArrayAsList extends AbstractList<Integer>
       this(array, 0, array.length);
     }
 
+    @SuppressWarnings(
+        "index" // these three fields need to be initialized in some order, and any ordering
+    // leads to the first two issuing errors - since each field is dependent on
+    // at least one of the others
+    )
     @SuppressWarnings("index:assignment") // these three fields need to be initialized in some order, and any ordering leads to the first two issuing errors - since each field is dependent on at least one of the others
     IntArrayAsList(int @MinLen(1)[] array, @IndexFor("#1") @LessThan("#3") int start, @IndexOrHigh("#1") int end) {
       this.array = array;
diff --git a/guava/src/com/google/common/primitives/Longs.java b/guava/src/com/google/common/primitives/Longs.java
index af6699bd81b3..32082d8aba6b 100644
--- a/guava/src/com/google/common/primitives/Longs.java
+++ b/guava/src/com/google/common/primitives/Longs.java
@@ -701,7 +701,10 @@ private static class LongArrayAsList extends AbstractList<Long>
     }
 
     @SuppressWarnings(
-            "index") // these three fields need to be initialized in some order, and any ordering leads to the first two issuing errors - since each field is dependent on at least one of the others
+        "index" // these three fields need to be initialized in some order, and any ordering
+    // leads to the first two issuing errors - since each field is dependent on
+    // at least one of the others
+    )
     LongArrayAsList(long @MinLen(1)[] array, @IndexFor("#1") @LessThan("#3") int start, @IndexOrHigh("#1") int end) {
       this.array = array;
       this.start = start;
diff --git a/guava/src/com/google/common/primitives/Shorts.java b/guava/src/com/google/common/primitives/Shorts.java
index 44368c1bab60..306369758f82 100644
--- a/guava/src/com/google/common/primitives/Shorts.java
+++ b/guava/src/com/google/common/primitives/Shorts.java
@@ -600,7 +600,10 @@ private static class ShortArrayAsList extends AbstractList<Short>
     }
 
     @SuppressWarnings(
-            "index") // these three fields need to be initialized in some order, and any ordering leads to the first two issuing errors - since each field is dependent on at least one of the others
+        "index" // these three fields need to be initialized in some order, and any ordering
+    // leads to the first two issuing errors - since each field is dependent on
+    // at least one of the others
+    )
     ShortArrayAsList(short @MinLen(1)[] array, @IndexFor("#1") @LessThan("#3") int start, @IndexOrHigh("#1") int end) {
       this.array = array;
       this.start = start;

From 936ac0653b5f55e2b93c84ea689980a7b338ccc3 Mon Sep 17 00:00:00 2001
From: Michael Ernst <mernst@cs.washington.edu>
Date: Sun, 14 May 2023 11:10:39 -0700
Subject: [PATCH 14/21] Be more explicit about running with a locally-built
 Checker Framework

---
 README-typetools.md | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/README-typetools.md b/README-typetools.md
index 686bc55b429b..62dec84f125b 100644
--- a/README-typetools.md
+++ b/README-typetools.md
@@ -13,7 +13,10 @@ To create file `guava/target/guava-HEAD-jre-SNAPSHOT.jar`:
 (cd guava && mvn -B package -Dmaven.test.skip=true -Danimal.sniffer.skip=true)
 ```
 
-To use a locally-built Checker Framework, add `-P checkerframework-local`,
+To use a locally-built Checker Framework:
+```
+(cd guava && mvn -B package -Dmaven.test.skip=true -Danimal.sniffer.skip=true -P checkerframework-local)
+```
 or change `guava/pom.xml`.
 
 

From 246c8ce32967d931714c153d1a719b3b1971b89d Mon Sep 17 00:00:00 2001
From: Mark Roberts <markro49@users.noreply.github.com>
Date: Sun, 14 May 2023 14:01:54 -0700
Subject: [PATCH 15/21] More `@SuppressionWarnings` cleanup

---
 .../com/google/common/cache/LongAdder.java    | 24 +++++++++---------
 .../common/collect/ForwardingCollection.java  |  3 ++-
 .../src/com/google/common/hash/LongAdder.java | 25 +++++++++----------
 .../google/common/primitives/Booleans.java    |  4 +--
 .../com/google/common/primitives/Bytes.java   | 18 ++++++-------
 .../com/google/common/primitives/Chars.java   |  2 --
 .../common/primitives/ImmutableIntArray.java  |  5 ++--
 .../com/google/common/primitives/Ints.java    |  5 ++--
 .../com/google/common/primitives/Shorts.java  |  1 -
 .../common/primitives/UnsignedBytes.java      |  6 ++---
 .../common/primitives/UnsignedInteger.java    |  2 +-
 .../common/primitives/UnsignedLong.java       | 15 +++++------
 .../common/util/concurrent/AtomicDouble.java  |  4 ++-
 13 files changed, 56 insertions(+), 58 deletions(-)

diff --git a/guava/src/com/google/common/cache/LongAdder.java b/guava/src/com/google/common/cache/LongAdder.java
index ba9e72029c85..e296b8f3747d 100644
--- a/guava/src/com/google/common/cache/LongAdder.java
+++ b/guava/src/com/google/common/cache/LongAdder.java
@@ -158,31 +158,31 @@ public String toString() {
    *
    * @return the sum
    */
+  @SuppressWarnings("override.return")  // superclass Number requires @PolyValue, but that is unverifiable and unlikely to be useful to clients
   @Override
-  @SuppressWarnings("cast.unsafe")
-  public @PolyValue long longValue(@PolyValue LongAdder this) {
-    return (@PolyValue long) sum();
+  public long longValue() {
+    return sum();
   }
 
   /** Returns the {@link #sum} as an {@code int} after a narrowing primitive conversion. */
+  @SuppressWarnings("override.return")  // superclass Number requires @PolyValue, but that is unverifiable and unlikely to be useful to clients
   @Override
-  @SuppressWarnings("cast.unsafe")
-  public @PolyValue int intValue(@PolyValue LongAdder this) {
-    return (@PolyValue int) sum();
+  public int intValue() {
+    return (int) sum();
   }
 
   /** Returns the {@link #sum} as a {@code float} after a widening primitive conversion. */
+  @SuppressWarnings("override.return")  // superclass Number requires @PolyValue, but that is unverifiable and unlikely to be useful to clients
   @Override
-  @SuppressWarnings("cast.unsafe")
-  public @PolyValue float floatValue(@PolyValue LongAdder this) {
-    return (@PolyValue float) sum();
+  public float floatValue() {
+    return (float) sum();
   }
 
   /** Returns the {@link #sum} as a {@code double} after a widening primitive conversion. */
+  @SuppressWarnings("override.return")  // superclass Number requires @PolyValue, but that is unverifiable and unlikely to be useful to clients
   @Override
-  @SuppressWarnings("cast.unsafe")
-  public @PolyValue double doubleValue(@PolyValue LongAdder this) {
-    return (@PolyValue double) sum();
+  public double doubleValue() {
+    return (double) sum();
   }
 
   private void writeObject(ObjectOutputStream s) throws IOException {
diff --git a/guava/src/com/google/common/collect/ForwardingCollection.java b/guava/src/com/google/common/collect/ForwardingCollection.java
index 11e71fc04b5d..55f8c7651fb3 100644
--- a/guava/src/com/google/common/collect/ForwardingCollection.java
+++ b/guava/src/com/google/common/collect/ForwardingCollection.java
@@ -22,6 +22,7 @@
 import java.util.Collection;
 import java.util.Iterator;
 import javax.annotation.CheckForNull;
+import org.checkerframework.checker.index.qual.NonNegative;
 import org.checkerframework.checker.nullness.qual.Nullable;
 import org.checkerframework.checker.nullness.qual.PolyNull;
 import org.checkerframework.checker.signedness.qual.PolySigned;
@@ -71,7 +72,7 @@ public Iterator<E> iterator() {
 
   @Pure
   @Override
-  public int size() {
+  public @NonNegative int size() {
     return delegate().size();
   }
 
diff --git a/guava/src/com/google/common/hash/LongAdder.java b/guava/src/com/google/common/hash/LongAdder.java
index 0eaaf7ec7875..ab6ac0795536 100644
--- a/guava/src/com/google/common/hash/LongAdder.java
+++ b/guava/src/com/google/common/hash/LongAdder.java
@@ -17,7 +17,6 @@
 import java.io.Serializable;
 import java.util.concurrent.atomic.AtomicLong;
 import org.checkerframework.common.value.qual.MinLen;
-import org.checkerframework.common.value.qual.PolyValue;
 
 /**
  * One or more variables that together maintain an initially zero {@code long} sum. When updates
@@ -159,31 +158,31 @@ public String toString() {
    *
    * @return the sum
    */
+  @SuppressWarnings("override.return")  // superclass Number requires @PolyValue, but that is unverifiable and unlikely to be useful to clients
   @Override
-  @SuppressWarnings("cast.unsafe")
-  public @PolyValue long longValue(@PolyValue LongAdder this) {
-    return (@PolyValue long)sum();
+  public long longValue() {
+    return sum();
   }
 
   /** Returns the {@link #sum} as an {@code int} after a narrowing primitive conversion. */
+  @SuppressWarnings("override.return")  // superclass Number requires @PolyValue, but that is unverifiable and unlikely to be useful to clients
   @Override
-  @SuppressWarnings("cast.unsafe")
-  public @PolyValue int intValue(@PolyValue LongAdder this) {
-    return (@PolyValue int) sum();
+  public int intValue() {
+    return (int) sum();
   }
 
   /** Returns the {@link #sum} as a {@code float} after a widening primitive conversion. */
+  @SuppressWarnings("override.return")  // superclass Number requires @PolyValue, but that is unverifiable and unlikely to be useful to clients
   @Override
-  @SuppressWarnings("cast.unsafe")
-  public @PolyValue float floatValue(@PolyValue LongAdder this) {
-    return (@PolyValue float) sum();
+  public float floatValue() {
+    return (float) sum();
   }
 
   /** Returns the {@link #sum} as a {@code double} after a widening primitive conversion. */
+  @SuppressWarnings("override.return")  // superclass Number requires @PolyValue, but that is unverifiable and unlikely to be useful to clients
   @Override
-  @SuppressWarnings("cast.unsafe")
-  public @PolyValue double doubleValue(@PolyValue LongAdder this) {
-    return (@PolyValue double) sum();
+  public double doubleValue() {
+    return (double) sum();
   }
 
   private void writeObject(ObjectOutputStream s) throws IOException {
diff --git a/guava/src/com/google/common/primitives/Booleans.java b/guava/src/com/google/common/primitives/Booleans.java
index 2f16b2414d9f..4b4dc5b3250a 100644
--- a/guava/src/com/google/common/primitives/Booleans.java
+++ b/guava/src/com/google/common/primitives/Booleans.java
@@ -447,10 +447,10 @@ public boolean contains(@CheckForNull @UnknownSignedness Object target) {
     }
 
     @Override
-    @SuppressWarnings("signedness:cast.unsafe") // CF bug? Boolean should always be @Signed
     public @IndexOrLow("this") int indexOf(@CheckForNull @UnknownSignedness Object target) {
       // Overridden to prevent a ton of boxing
       if (target instanceof Boolean) {
+        @SuppressWarnings("signedness:cast.unsafe") // https://github.com/typetools/checker-framework/pull/5862
         int i = Booleans.indexOf(array, (@Signed Boolean) target, start, end);
         if (i >= 0) {
           return i - start;
@@ -460,10 +460,10 @@ public boolean contains(@CheckForNull @UnknownSignedness Object target) {
     }
 
     @Override
-    @SuppressWarnings("signedness:cast.unsafe") // CF bug? Boolean should always be @Signed
     public @IndexOrLow("this") int lastIndexOf(@CheckForNull @UnknownSignedness Object target) {
       // Overridden to prevent a ton of boxing
       if (target instanceof Boolean) {
+        @SuppressWarnings("signedness:cast.unsafe") // https://github.com/typetools/checker-framework/pull/5862
         int i = Booleans.lastIndexOf(array, (@Signed Boolean) target, start, end);
         if (i >= 0) {
           return i - start;
diff --git a/guava/src/com/google/common/primitives/Bytes.java b/guava/src/com/google/common/primitives/Bytes.java
index 833297e7ddcf..5c7bb7135059 100644
--- a/guava/src/com/google/common/primitives/Bytes.java
+++ b/guava/src/com/google/common/primitives/Bytes.java
@@ -75,8 +75,9 @@ private Bytes() {}
    * @param value a primitive {@code byte} value
    * @return a hash code for the value
    */
+  @SuppressWarnings("signedness:cast.unsafe") // UnknownSignedness byte to Signed int is ok for hashing
   public static int hashCode(@UnknownSignedness byte value) {
-    return value;
+    return (@Signed int) value;
   }
 
   /**
@@ -182,15 +183,15 @@ public static boolean contains(@PolySigned byte[] array, @PolySigned byte target
    * pos is increased the same way as length, so pos points to a valid
    * range of length array.length in result.
    */
-  @SuppressWarnings("upperbound:argument") // sum of lengths
+  @SuppressWarnings("signedness:enhancedfor")
   public static @PolySigned byte[] concat(@PolySigned byte[]... arrays) {
     int length = 0;
     for (byte[] array : arrays) {
       length += array.length;
     }
-    byte[] result = new byte[length];
+    @PolySigned byte[] result = new byte[length];
     int pos = 0;
-    for (byte[] array : arrays) {
+    for (@PolySigned byte[] array : arrays) {
       System.arraycopy(array, 0, result, pos, array.length);
       pos += array.length;
     }
@@ -229,14 +230,15 @@ public static boolean contains(@PolySigned byte[] array, @PolySigned byte target
    * @throws NullPointerException if {@code collection} or any of its elements is null
    * @since 1.0 (parameter was {@code Collection<Byte>} before 12.0)
    */
+  @SuppressWarnings("signedness:return") // Signed byte to PolySigned byte is ok
   public static <T extends Number> @PolySigned byte[] toArray(Collection<@PolySigned T> collection) {
     if (collection instanceof ByteArrayAsList) {
       return ((ByteArrayAsList) collection).toByteArray();
     }
 
-    Object[] boxedArray = collection.toArray();
+    @PolySigned Object[] boxedArray = collection.toArray();
     int len = boxedArray.length;
-    byte[] array = new byte[len];
+    @PolySigned byte[] array = new byte[len];
     for (int i = 0; i < len; i++) {
       // checkNotNull for GWT (do not optimize)
       array[i] = ((Number) checkNotNull(boxedArray[i])).byteValue();
@@ -256,6 +258,7 @@ public static boolean contains(@PolySigned byte[] array, @PolySigned byte target
    * @param backingArray the array to back the list
    * @return a list view of the array
    */
+  @SuppressWarnings({"signedness:argument", "signedness:return"}) // non-generic container class
   public static List<@PolySigned Byte> asList(@PolySigned byte... backingArray) {
     if (backingArray.length == 0) {
       return Collections.emptyList();
@@ -305,14 +308,12 @@ public Byte get(@IndexFor("this") int index) {
     }
 
     @Override
-    @SuppressWarnings("signedness:cast.unsafe") // non-generic container class
     public boolean contains(@CheckForNull @UnknownSignedness Object target) {
       // Overridden to prevent a ton of boxing
       return (target instanceof Byte) && Bytes.indexOf(array, (Byte) target, start, end) != -1;
     }
 
     @Override
-    @SuppressWarnings("signedness:cast.unsafe") // non-generic container class
     public @IndexOrLow("this") int indexOf(@CheckForNull @UnknownSignedness Object target) {
       // Overridden to prevent a ton of boxing
       if (target instanceof Byte) {
@@ -325,7 +326,6 @@ public boolean contains(@CheckForNull @UnknownSignedness Object target) {
     }
 
     @Override
-    @SuppressWarnings("signedness:cast.unsafe") // non-generic container class
     public @IndexOrLow("this") int lastIndexOf(@CheckForNull @UnknownSignedness Object target) {
       // Overridden to prevent a ton of boxing
       if (target instanceof Byte) {
diff --git a/guava/src/com/google/common/primitives/Chars.java b/guava/src/com/google/common/primitives/Chars.java
index d1f1f412be3f..a53bb8a6caff 100644
--- a/guava/src/com/google/common/primitives/Chars.java
+++ b/guava/src/com/google/common/primitives/Chars.java
@@ -350,7 +350,6 @@ public static char fromByteArray(byte @MinLen(Chars.BYTES)[] bytes) {
    *
    * @since 7.0
    */
-  @SuppressWarnings("signedness:cast.unsafe") // the bytes are bit patterns
   @GwtIncompatible // doesn't work
   public static char fromBytes(@SignednessGlb byte b1, @SignednessGlb byte b2) {
     return (char) ((b1 << 8) | (b2 & 0xFF));
@@ -455,7 +454,6 @@ public static char[] toArray(Collection<Character> collection) {
       return ((CharArrayAsList) collection).toCharArray();
     }
 
-    @SuppressWarnings("signedness:assignment") // chars are always unsigned
     @Unsigned Object[] boxedArray = collection.toArray();
     int len = boxedArray.length;
     char[] array = new char[len];
diff --git a/guava/src/com/google/common/primitives/ImmutableIntArray.java b/guava/src/com/google/common/primitives/ImmutableIntArray.java
index 68ae29933350..5d983e2bcd56 100644
--- a/guava/src/com/google/common/primitives/ImmutableIntArray.java
+++ b/guava/src/com/google/common/primitives/ImmutableIntArray.java
@@ -548,9 +548,8 @@ public Integer get(@IndexFor("this") int index) {
     }
 
     @Override
-    @SuppressWarnings("signedness:cast.unsafe")
     public boolean contains(@CheckForNull @UnknownSignedness Object target) {
-      return indexOf((@Signed Integer) target) >= 0;
+      return indexOf(target) >= 0;
     }
 
     @Override
@@ -623,7 +622,7 @@ public String toString() {
    * values as this one, in the same order.
    */
   @Override
-  public boolean equals(@CheckForNull @UnknownSignedness Object object) {
+  public boolean equals(@CheckForNull Object object) {
     if (object == this) {
       return true;
     }
diff --git a/guava/src/com/google/common/primitives/Ints.java b/guava/src/com/google/common/primitives/Ints.java
index 683e4f47300e..906dcc3325f4 100644
--- a/guava/src/com/google/common/primitives/Ints.java
+++ b/guava/src/com/google/common/primitives/Ints.java
@@ -607,7 +607,6 @@ private static class IntArrayAsList extends AbstractList<Integer>
     // leads to the first two issuing errors - since each field is dependent on
     // at least one of the others
     )
-    @SuppressWarnings("index:assignment") // these three fields need to be initialized in some order, and any ordering leads to the first two issuing errors - since each field is dependent on at least one of the others
     IntArrayAsList(int @MinLen(1)[] array, @IndexFor("#1") @LessThan("#3") int start, @IndexOrHigh("#1") int end) {
       this.array = array;
       this.start = start;
@@ -636,7 +635,7 @@ public Spliterator.OfInt spliterator() {
     }
 
     @Override
-    @SuppressWarnings("signedness:cast.unsafe")
+    @SuppressWarnings("signedness:cast.unsafe") // non-generic container class
     public boolean contains(@CheckForNull @UnknownSignedness Object target) {
       // Overridden to prevent a ton of boxing
       return (target instanceof Integer) && Ints.indexOf(array, (@Signed Integer) target, start, end) != -1;
@@ -657,7 +656,7 @@ public boolean contains(@CheckForNull @UnknownSignedness Object target) {
 
     @Override
     @SuppressWarnings("signedness:cast.unsafe") // non-generic container class
-    public @IndexOrLow("this")int lastIndexOf(@CheckForNull @UnknownSignedness Object target) {
+    public @IndexOrLow("this") int lastIndexOf(@CheckForNull @UnknownSignedness Object target) {
       // Overridden to prevent a ton of boxing
       if (target instanceof Integer) {
         int i = Ints.lastIndexOf(array, (@Signed Integer) target, start, end);
diff --git a/guava/src/com/google/common/primitives/Shorts.java b/guava/src/com/google/common/primitives/Shorts.java
index 306369758f82..8c0b53195f47 100644
--- a/guava/src/com/google/common/primitives/Shorts.java
+++ b/guava/src/com/google/common/primitives/Shorts.java
@@ -633,7 +633,6 @@ public boolean contains(@CheckForNull @UnknownSignedness Object target) {
       return (target instanceof Short) && Shorts.indexOf(array, (@Signed Short) target, start, end) != -1;
     }
 
-
     @Override
     @SuppressWarnings("signedness:cast.unsafe") // non-generic container class
     public @IndexOrLow("this") int indexOf(@CheckForNull @UnknownSignedness Object target) {
diff --git a/guava/src/com/google/common/primitives/UnsignedBytes.java b/guava/src/com/google/common/primitives/UnsignedBytes.java
index ef7d0d977bf0..4167cd664ce0 100644
--- a/guava/src/com/google/common/primitives/UnsignedBytes.java
+++ b/guava/src/com/google/common/primitives/UnsignedBytes.java
@@ -64,7 +64,7 @@ private UnsignedBytes() {}
    *
    * @since 10.0
    */
-  @SuppressWarnings("cast.unsafe") // https://github.com/kelloggm/checker-framework/issues/149
+  @SuppressWarnings("value:cast.unsafe") // https://github.com/kelloggm/checker-framework/issues/149
   public static final @Unsigned byte MAX_POWER_OF_TWO = (byte) 0x80;
 
   /**
@@ -72,7 +72,7 @@ private UnsignedBytes() {}
    *
    * @since 13.0
    */
-  @SuppressWarnings("cast.unsafe") // https://github.com/kelloggm/checker-framework/issues/149
+  @SuppressWarnings("value:cast.unsafe") // https://github.com/kelloggm/checker-framework/issues/149
   public static final @Unsigned byte MAX_VALUE = (byte) 0xFF;
 
   private static final int UNSIGNED_MASK = 0xFF;
@@ -475,7 +475,7 @@ public String toString() {
     }
   }
 
-  //@SuppressWarnings("signedness:return") // https://github.com/typetools/checker-framework/issues/5773
+  @SuppressWarnings("signedness:cast.unsafe") // https://github.com/typetools/checker-framework/issues/5773
   private static @PolySigned byte flip(@PolySigned byte b) {
     return (@PolySigned byte) (b ^ 0x80);
   }
diff --git a/guava/src/com/google/common/primitives/UnsignedInteger.java b/guava/src/com/google/common/primitives/UnsignedInteger.java
index ab608301b7e1..888031d4ae2f 100644
--- a/guava/src/com/google/common/primitives/UnsignedInteger.java
+++ b/guava/src/com/google/common/primitives/UnsignedInteger.java
@@ -72,6 +72,7 @@ private UnsignedInteger(int value) {
    *
    * @since 14.0
    */
+  @SuppressWarnings("signedness:argument") // @UnknownSignedness doesn't matter
   public static UnsignedInteger fromIntBits(@UnknownSignedness int bits) {
     return new UnsignedInteger(bits);
   }
@@ -121,7 +122,6 @@ public static UnsignedInteger valueOf(String string) {
    * @throws NumberFormatException if the string does not contain a parsable unsigned {@code int}
    *     value
    */
-  @SuppressWarnings("signedness:argument") // parseUnsignedInt guarantees value fits in int
   public static UnsignedInteger valueOf(String string, @IntRange(from=2, to=36) int radix) {
     return fromIntBits(UnsignedInts.parseUnsignedInt(string, radix));
   }
diff --git a/guava/src/com/google/common/primitives/UnsignedLong.java b/guava/src/com/google/common/primitives/UnsignedLong.java
index 848d355fde80..af72b5d55ca7 100644
--- a/guava/src/com/google/common/primitives/UnsignedLong.java
+++ b/guava/src/com/google/common/primitives/UnsignedLong.java
@@ -98,7 +98,7 @@ public static UnsignedLong valueOf(@NonNegative long value) {
    * @throws IllegalArgumentException if {@code value} is negative or {@code value >= 2^64}
    */
   @CanIgnoreReturnValue
-  @SuppressWarnings("signedness:cast.unsafe")
+  @SuppressWarnings("signedness:cast.unsafe") // checkArgument guarantees value fits in Unsigned long
   public static UnsignedLong valueOf(BigInteger value) {
     checkNotNull(value);
     checkArgument(
@@ -183,9 +183,9 @@ public UnsignedLong mod(UnsignedLong val) {
 
   /** Returns the value of this {@code UnsignedLong} as an {@code int}. */
   @Override
-  @SuppressWarnings("return")
+  @SuppressWarnings("cast.unsafe") // Unsigned long to Signed int is function intention
   public @PolyValue int intValue(@PolyValue UnsignedLong this) {
-    return (int) value;
+    return (@PolyValue @Signed int) value;
   }
 
   /**
@@ -196,18 +196,19 @@ public UnsignedLong mod(UnsignedLong val) {
    * will be equal to {@code this - 2^64}.
    */
   @Override
-  @SuppressWarnings("return")
+  @SuppressWarnings("cast.unsafe") // Unsigned long to Signed long is function intention
   public @PolyValue long longValue(@PolyValue UnsignedLong this) {
-    return value;
+    return (@PolyValue @Signed long) value;
   }
 
   /**
    * Returns the value of this {@code UnsignedLong} as a {@code float}, analogous to a widening
    * primitive conversion from {@code long} to {@code float}, and correctly rounded.
    */
+  @Override
   @SuppressWarnings({
     "signedness:comparison", // unsigned compare
-    "value:return" // forDigit
+    "value:return" // bit manipulation preserves value from integral to float
   })
   public @PolyValue float floatValue(@PolyValue UnsignedLong this) {
     if (value >= 0) {
@@ -225,7 +226,7 @@ public UnsignedLong mod(UnsignedLong val) {
   @Override
   @SuppressWarnings({
     "signedness:comparison", // unsigned compare
-    "value:return" // forDigit
+    "value:return" // bit manipulation preserves value from integral to double
   })
   public @PolyValue double doubleValue(@PolyValue UnsignedLong this) {
     if (value >= 0) {
diff --git a/guava/src/com/google/common/util/concurrent/AtomicDouble.java b/guava/src/com/google/common/util/concurrent/AtomicDouble.java
index cdd63a8b86b9..2a0c09e51f3c 100644
--- a/guava/src/com/google/common/util/concurrent/AtomicDouble.java
+++ b/guava/src/com/google/common/util/concurrent/AtomicDouble.java
@@ -62,6 +62,7 @@
 public class AtomicDouble extends Number implements java.io.Serializable {
   private static final long serialVersionUID = 0L;
 
+  // This is not a long integral value, but the bit pattern for a double value.
   private transient volatile long value;
 
   private static final AtomicLongFieldUpdater<AtomicDouble> updater =
@@ -86,7 +87,8 @@ public AtomicDouble() {
    *
    * @return the current value
    */
-  public final double get() {
+  @SuppressWarnings("value:return") // bit manipulation of double representation
+  public final @PolyValue double get(@PolyValue AtomicDouble this) {
     return longBitsToDouble(value);
   }
 

From 3a914ca877d75c29ec6e4fc00b52e7d90eb9eccf Mon Sep 17 00:00:00 2001
From: Michael Ernst <mernst@alum.mit.edu>
Date: Tue, 30 May 2023 08:53:30 -0700
Subject: [PATCH 16/21] Use the same Checker Framework configuration for all
 JDKs >= 9 (#73)

Co-authored-by: Werner Dietl <wdietl@gmail.com>
---
 guava/pom.xml | 25 ++-----------------------
 1 file changed, 2 insertions(+), 23 deletions(-)

diff --git a/guava/pom.xml b/guava/pom.xml
index e93151f8e12b..3f1babf56d38 100644
--- a/guava/pom.xml
+++ b/guava/pom.xml
@@ -397,30 +397,9 @@
       </dependencies>
     </profile>
     <profile>
-      <id>jdk11</id>
+      <id>jdk9plus</id>
       <activation>
-        <jdk>11</jdk>
-      </activation>
-      <build>
-        <plugins>
-          <plugin>
-            <groupId>org.apache.maven.plugins</groupId>
-            <artifactId>maven-compiler-plugin</artifactId>
-            <configuration>
-              <fork>true</fork>
-              <maxmem>6000m</maxmem>
-              <compilerArgs combine.children="append">
-                <arg>-J--add-opens=jdk.compiler/com.sun.tools.javac.comp=ALL-UNNAMED</arg>
-              </compilerArgs>
-            </configuration>
-          </plugin>
-        </plugins>
-      </build>
-    </profile>
-    <profile>
-      <id>jdk17</id>
-      <activation>
-        <jdk>[16,)</jdk>
+        <jdk>[9,)</jdk>
       </activation>
       <build>
         <plugins>

From e03b45dae44541804487e6c77d59ac6b5140879a Mon Sep 17 00:00:00 2001
From: Mark Roberts <markro49@users.noreply.github.com>
Date: Tue, 30 May 2023 11:35:20 -0700
Subject: [PATCH 17/21] Fixes for 'cannot override' messages, plus signedness
 annotations (#72)

Co-authored-by: Michael Ernst <mernst@cs.washington.edu>
---
 android/pom.xml                               |   2 +-
 guava/pom.xml                                 |   2 +-
 guava/src/com/google/common/base/Objects.java |   3 +-
 .../common/base/PairwiseEquivalence.java      |   2 +-
 guava/src/com/google/common/base/Present.java |   8 +-
 guava/src/com/google/common/base/Utf8.java    |   1 -
 .../com/google/common/cache/LocalCache.java   |  10 +-
 .../google/common/collect/AbstractBiMap.java  |  28 +++--
 .../collect/AbstractMapBasedMultimap.java     |  17 +--
 .../collect/AbstractMapBasedMultiset.java     |   4 +-
 .../common/collect/AbstractMultimap.java      |   2 +-
 .../common/collect/AbstractNavigableMap.java  |  11 +-
 .../AbstractSortedKeySortedSetMultimap.java   |   1 +
 .../google/common/collect/AbstractTable.java  |   2 +-
 .../common/collect/ArrayListMultimap.java     |   5 +-
 .../com/google/common/collect/ArrayTable.java |  12 ++-
 .../common/collect/CollectPreconditions.java  |  11 +-
 .../google/common/collect/Collections2.java   |   7 +-
 .../google/common/collect/CompactHashMap.java |   5 +-
 .../google/common/collect/CompactHashSet.java |   1 -
 .../common/collect/CompactLinkedHashMap.java  |  13 ++-
 .../common/collect/CompactLinkedHashSet.java  |   6 +-
 .../collect/ConcurrentHashMultiset.java       |  20 ++--
 .../DescendingImmutableSortedMultiset.java    |   4 +-
 .../common/collect/DescendingMultiset.java    |   3 +-
 .../com/google/common/collect/EnumBiMap.java  |   5 +-
 .../google/common/collect/EnumHashBiMap.java  |   3 +-
 .../google/common/collect/EnumMultiset.java   |   4 +-
 .../google/common/collect/EvictingQueue.java  |   4 +-
 .../common/collect/FilteredEntryMultimap.java |   9 +-
 .../common/collect/FilteredKeyMultimap.java   |   5 +-
 .../collect/FilteredMultimapValues.java       |   3 +-
 .../common/collect/ForwardingCollection.java  |   2 +-
 .../google/common/collect/ForwardingMap.java  |   5 +-
 .../common/collect/ForwardingMultimap.java    |   5 +-
 .../common/collect/ForwardingMultiset.java    |   3 +-
 .../collect/ForwardingNavigableMap.java       |   5 +-
 .../common/collect/ForwardingSortedMap.java   |   5 +-
 .../common/collect/ForwardingTable.java       |   3 +-
 .../com/google/common/collect/HashBiMap.java  |  22 ++--
 .../google/common/collect/HashMultiset.java   |   4 +-
 .../google/common/collect/ImmutableBiMap.java |   5 +-
 .../common/collect/ImmutableCollection.java   |   2 +-
 .../common/collect/ImmutableEnumMap.java      |   3 +-
 .../google/common/collect/ImmutableMap.java   |  20 ++--
 .../common/collect/ImmutableMultimap.java     |   7 +-
 .../common/collect/ImmutableSortedMap.java    |  16 +--
 .../common/collect/ImmutableSortedSet.java    |   5 +-
 .../google/common/collect/ImmutableTable.java |   3 +-
 .../com/google/common/collect/Iterators.java  |   3 +-
 .../collect/JdkBackedImmutableMultiset.java   |   4 +-
 .../common/collect/LinkedHashMultimap.java    |   4 +-
 .../common/collect/LinkedHashMultiset.java    |   3 +-
 .../common/collect/LinkedListMultimap.java    |   7 +-
 .../src/com/google/common/collect/Lists.java  |   6 +-
 .../common/collect/MapMakerInternalMap.java   |  38 ++++---
 guava/src/com/google/common/collect/Maps.java | 101 +++++++++---------
 .../common/collect/MinMaxPriorityQueue.java   |   4 +-
 .../com/google/common/collect/Multimap.java   |   5 +-
 .../com/google/common/collect/Multimaps.java  |  14 +--
 .../com/google/common/collect/Multisets.java  |  13 +--
 .../collect/MutableClassToInstanceMap.java    |  12 ++-
 .../google/common/collect/ObjectArrays.java   |   7 +-
 .../common/collect/RegularImmutableMap.java   |   5 +-
 .../collect/RegularImmutableMultiset.java     |   4 +-
 .../RegularImmutableSortedMultiset.java       |   4 +-
 guava/src/com/google/common/collect/Sets.java |   2 +-
 .../collect/SingletonImmutableBiMap.java      |   7 +-
 .../collect/StandardRowSortedTable.java       |   7 +-
 .../google/common/collect/StandardTable.java  |  54 +++++-----
 .../google/common/collect/Synchronized.java   |  39 +++----
 .../src/com/google/common/collect/Table.java  |   3 +-
 .../src/com/google/common/collect/Tables.java |   5 +-
 .../google/common/collect/TreeBasedTable.java |   7 +-
 .../google/common/collect/TreeMultimap.java   |   1 +
 .../google/common/collect/TreeMultiset.java   |   4 +-
 .../google/common/collect/TreeRangeMap.java   |  14 +--
 .../google/common/graph/MapIteratorCache.java |   2 +-
 .../google/common/io/ByteArrayDataOutput.java |   3 +-
 .../src/com/google/common/io/ByteStreams.java |   2 +-
 .../com/google/common/net/InetAddresses.java  |   5 -
 .../common/primitives/UnsignedBytes.java      |   2 -
 .../reflect/MutableTypeToInstanceMap.java     |   3 +-
 .../common/util/concurrent/AtomicLongMap.java |   3 +-
 pom.xml                                       |   2 +-
 85 files changed, 418 insertions(+), 309 deletions(-)

diff --git a/android/pom.xml b/android/pom.xml
index 40e437cebfd9..4e58c263d16b 100644
--- a/android/pom.xml
+++ b/android/pom.xml
@@ -15,7 +15,7 @@
     <!-- Override this with -Dtest.include="**/SomeTest.java" on the CLI -->
     <test.include>%regex[.*.class]</test.include>
     <truth.version>1.1.2</truth.version>
-    <checker-framework.version>3.32.0</checker-framework.version>
+    <checker-framework.version>3.34.0</checker-framework.version>
     <animal.sniffer.version>1.20</animal.sniffer.version>
     <maven-javadoc-plugin.version>3.1.0</maven-javadoc-plugin.version>
     <!-- Empty for all JDKs but 9-12 -->
diff --git a/guava/pom.xml b/guava/pom.xml
index 3f1babf56d38..7e495d6b2162 100644
--- a/guava/pom.xml
+++ b/guava/pom.xml
@@ -91,7 +91,7 @@
     <dependency>
       <groupId>org.checkerframework</groupId>
       <artifactId>checker</artifactId>
-      <version>3.32.0</version>
+      <version>3.34.0</version>
     </dependency>
   </dependencies>
   <build>
diff --git a/guava/src/com/google/common/base/Objects.java b/guava/src/com/google/common/base/Objects.java
index c63ebc02487a..13bc37f797a1 100644
--- a/guava/src/com/google/common/base/Objects.java
+++ b/guava/src/com/google/common/base/Objects.java
@@ -18,6 +18,7 @@
 import java.util.Arrays;
 import javax.annotation.CheckForNull;
 import org.checkerframework.checker.nullness.qual.Nullable;
+import org.checkerframework.checker.signedness.qual.PolySigned;
 import org.checkerframework.dataflow.qual.Pure;
 import org.checkerframework.framework.qual.AnnotatedFor;
 
@@ -53,7 +54,7 @@ private Objects() {}
    * <p><b>Note for Java 7 and later:</b> This method should be treated as deprecated; use {@link
    * java.util.Objects#equals} instead.
    */
-  public static boolean equal(@CheckForNull Object a, @CheckForNull Object b) {
+  public static boolean equal(@CheckForNull @PolySigned Object a, @CheckForNull @PolySigned Object b) {
     return a == b || (a != null && a.equals(b));
   }
 
diff --git a/guava/src/com/google/common/base/PairwiseEquivalence.java b/guava/src/com/google/common/base/PairwiseEquivalence.java
index 74be27fd7c6f..64b438bb9f1a 100644
--- a/guava/src/com/google/common/base/PairwiseEquivalence.java
+++ b/guava/src/com/google/common/base/PairwiseEquivalence.java
@@ -22,7 +22,7 @@
 
 @GwtCompatible(serializable = true)
 @ElementTypesAreNonnullByDefault
-final class PairwiseEquivalence<E, T extends @Nullable E> extends Equivalence<Iterable<T>>
+final class PairwiseEquivalence<E, T extends E> extends Equivalence<Iterable<T>>
     implements Serializable {
   final Equivalence<E> elementEquivalence;
 
diff --git a/guava/src/com/google/common/base/Present.java b/guava/src/com/google/common/base/Present.java
index 9620877523df..20ab94a2c2ec 100644
--- a/guava/src/com/google/common/base/Present.java
+++ b/guava/src/com/google/common/base/Present.java
@@ -39,12 +39,12 @@ public boolean isPresent() {
   }
 
   @Override
-  public T get() {
+  public @NonNull T get() {
     return reference;
   }
 
   @Override
-  public T or(T defaultValue) {
+  public @NonNull T or(T defaultValue) {
     checkNotNull(defaultValue, "use Optional.orNull() instead of Optional.or(null)");
     return reference;
   }
@@ -56,7 +56,7 @@ public Optional<T> or(Optional<? extends T> secondChoice) {
   }
 
   @Override
-  public T or(Supplier<? extends T> supplier) {
+  public @NonNull T or(Supplier<? extends T> supplier) {
     checkNotNull(supplier);
     return reference;
   }
@@ -67,7 +67,7 @@ public T orNull() {
   }
 
   @Override
-  public Set<T> asSet() {
+  public Set<@NonNull T> asSet() {
     return Collections.singleton(reference);
   }
 
diff --git a/guava/src/com/google/common/base/Utf8.java b/guava/src/com/google/common/base/Utf8.java
index b8087be6990f..8a42a25dea1e 100644
--- a/guava/src/com/google/common/base/Utf8.java
+++ b/guava/src/com/google/common/base/Utf8.java
@@ -144,7 +144,6 @@ public static boolean isWellFormed(byte[] bytes, @IndexOrHigh("#1") int off, @No
   }
 
   @SuppressWarnings({
-    "value:cast.unsafe", // https://github.com/kelloggm/checker-framework/issues/149
     "upperbound:unary.increment",
     "upperbound:array.access.unsafe.high" // https://github.com/kelloggm/checker-framework/issues/158
   })
diff --git a/guava/src/com/google/common/cache/LocalCache.java b/guava/src/com/google/common/cache/LocalCache.java
index 7bdaf3a89a5d..7dd0e9ccc509 100644
--- a/guava/src/com/google/common/cache/LocalCache.java
+++ b/guava/src/com/google/common/cache/LocalCache.java
@@ -85,7 +85,9 @@
 import java.util.function.Predicate;
 import java.util.logging.Level;
 import java.util.logging.Logger;
+import org.checkerframework.checker.nullness.qual.KeyFor;
 import org.checkerframework.checker.nullness.qual.Nullable;
+import org.checkerframework.checker.nullness.qual.PolyNull;
 import org.checkerframework.checker.signedness.qual.PolySigned;
 import org.checkerframework.checker.signedness.qual.UnknownSignedness;
 
@@ -4215,14 +4217,14 @@ public V compute(K key, BiFunction<? super K, ? super @Nullable V, ? extends V>
   }
 
   @Override
-  public V computeIfAbsent(K key, Function<? super K, ? extends V> function) {
+  public @PolyNull V computeIfAbsent(K key, Function<? super K, ? extends @PolyNull V> function) {
     checkNotNull(key);
     checkNotNull(function);
     return compute(key, (k, oldValue) -> (oldValue == null) ? function.apply(key) : oldValue);
   }
 
   @Override
-  public V computeIfPresent(K key, BiFunction<? super K, ? super V, ? extends V> function) {
+  public @PolyNull V computeIfPresent(K key, BiFunction<? super K, ? super V, ? extends @PolyNull V> function) {
     checkNotNull(key);
     checkNotNull(function);
     return compute(key, (k, oldValue) -> (oldValue == null) ? null : function.apply(k, oldValue));
@@ -4298,7 +4300,7 @@ void invalidateAll(Iterable<?> keys) {
   @RetainedWith @Nullable Set<K> keySet;
 
   @Override
-  public Set<K> keySet() {
+  public Set<@KeyFor({"this"}) K> keySet() {
     // does not impact recency ordering
     Set<K> ks = keySet;
     return (ks != null) ? ks : (keySet = new KeySet());
@@ -4317,7 +4319,7 @@ public Collection<V> values() {
 
   @Override
   @GwtIncompatible // Not supported.
-  public Set<Entry<K, V>> entrySet() {
+  public Set<Entry<@KeyFor({"this"}) K, V>> entrySet() {
     // does not impact recency ordering
     Set<Entry<K, V>> es = entrySet;
     return (es != null) ? es : (entrySet = new EntrySet());
diff --git a/guava/src/com/google/common/collect/AbstractBiMap.java b/guava/src/com/google/common/collect/AbstractBiMap.java
index 79c3338eee16..2461e956cf30 100644
--- a/guava/src/com/google/common/collect/AbstractBiMap.java
+++ b/guava/src/com/google/common/collect/AbstractBiMap.java
@@ -36,11 +36,15 @@
 import java.util.Set;
 import java.util.function.BiFunction;
 import javax.annotation.CheckForNull;
+import org.checkerframework.checker.nullness.qual.KeyFor;
 import org.checkerframework.checker.nullness.qual.Nullable;
 import org.checkerframework.checker.nullness.qual.PolyNull;
+import org.checkerframework.checker.signedness.qual.PolySigned;
+import org.checkerframework.checker.signedness.qual.UnknownSignedness;
 import org.checkerframework.dataflow.qual.Pure;
 import org.checkerframework.dataflow.qual.SideEffectFree;
 import org.checkerframework.framework.qual.AnnotatedFor;
+import org.checkerframework.framework.qual.CFComment;
 
 /**
  * A general-purpose bimap implementation using any two backing {@code Map} instances.
@@ -116,7 +120,7 @@ void setInverse(AbstractBiMap<V, K> inverse) {
 
   @Pure
   @Override
-  public boolean containsValue(@CheckForNull Object value) {
+  public boolean containsValue(@CheckForNull @UnknownSignedness Object value) {
     return inverse.containsKey(value);
   }
 
@@ -169,7 +173,7 @@ private void updateInverseMap(
   @CanIgnoreReturnValue
   @Override
   @CheckForNull
-  public V remove(@CheckForNull Object key) {
+  public V remove(@CheckForNull @UnknownSignedness Object key) {
     return containsKey(key) ? removeFromBothMaps(key) : null;
   }
 
@@ -235,7 +239,7 @@ public BiMap<V, K> inverse() {
 
   @SideEffectFree
   @Override
-  public Set<K> keySet() {
+  public Set<@KeyFor({"this"}) K> keySet() {
     Set<K> result = keySet;
     return (result == null) ? keySet = new KeySet() : result;
   }
@@ -253,7 +257,7 @@ public void clear() {
     }
 
     @Override
-    public boolean remove(@CheckForNull Object key) {
+    public boolean remove(@CheckForNull @UnknownSignedness Object key) {
       if (!contains(key)) {
         return false;
       }
@@ -304,14 +308,15 @@ public Iterator<V> iterator() {
       return Maps.valueIterator(entrySet().iterator());
     }
 
+    @CFComment("signedness: is same as signedness of V, which this method doesn't know")
     @Override
-    public @PolyNull Object[] toArray() {
+    public @PolyNull @PolySigned Object[] toArray(ValueSet this) {
       return standardToArray();
     }
 
     @Override
     @SuppressWarnings("nullness") // bug in our checker's handling of toArray signatures
-    public <T extends @Nullable Object> T[] toArray(T[] array) {
+    public <T extends @Nullable @UnknownSignedness Object> T[] toArray(T[] array) {
       return standardToArray(array);
     }
 
@@ -326,7 +331,7 @@ public String toString() {
 
   @SideEffectFree
   @Override
-  public Set<Entry<K, V>> entrySet() {
+  public Set<Entry<@KeyFor({"this"}) K, V>> entrySet() {
     Set<Entry<K, V>> result = entrySet;
     return (result == null) ? entrySet = new EntrySet() : result;
   }
@@ -404,7 +409,7 @@ public void clear() {
     }
 
     @Override
-    public boolean remove(@CheckForNull Object object) {
+    public boolean remove(@CheckForNull @UnknownSignedness Object object) {
       /*
        * `o instanceof Entry` is guaranteed by `contains`, but we check it here to satisfy our
        * nullness checker.
@@ -431,8 +436,9 @@ public Iterator<Entry<K, V>> iterator() {
 
     // See java.util.Collections.CheckedEntrySet for details on attacks.
 
+    @CFComment("signedeness: is same as V, which this method does not know")
     @Override
-    public Object[] toArray() {
+    public @PolyNull @PolySigned Object[] toArray() {
       /*
        * standardToArray returns `@Nullable Object[]` rather than `Object[]` but only because it can
        * be used with collections that may contain null. This collection never contains nulls, so we
@@ -445,13 +451,13 @@ public Object[] toArray() {
 
     @Override
     @SuppressWarnings("nullness") // bug in our checker's handling of toArray signatures
-    public <T extends @Nullable Object> T[] toArray(T[] array) {
+    public <T extends @Nullable @UnknownSignedness Object> T[] toArray(T[] array) {
       return standardToArray(array);
     }
 
     @Pure
     @Override
-    public boolean contains(@CheckForNull Object o) {
+    public boolean contains(@CheckForNull @UnknownSignedness Object o) {
       return Maps.containsEntryImpl(delegate(), o);
     }
 
diff --git a/guava/src/com/google/common/collect/AbstractMapBasedMultimap.java b/guava/src/com/google/common/collect/AbstractMapBasedMultimap.java
index 257f7376af25..a9a4525f7b61 100644
--- a/guava/src/com/google/common/collect/AbstractMapBasedMultimap.java
+++ b/guava/src/com/google/common/collect/AbstractMapBasedMultimap.java
@@ -45,6 +45,7 @@
 import java.util.Spliterator;
 import java.util.function.BiConsumer;
 import javax.annotation.CheckForNull;
+import org.checkerframework.checker.nullness.qual.KeyFor;
 import org.checkerframework.checker.nullness.qual.Nullable;
 import org.checkerframework.checker.signedness.qual.UnknownSignedness;
 
@@ -178,7 +179,7 @@ public int size() {
   }
 
   @Override
-  public boolean containsKey(@CheckForNull Object key) {
+  public boolean containsKey(@CheckForNull @UnknownSignedness Object key) {
     return map.containsKey(key);
   }
 
@@ -1375,7 +1376,7 @@ public Collection<V> get(@CheckForNull @UnknownSignedness Object key) {
     }
 
     @Override
-    public Set<K> keySet() {
+    public Set<@KeyFor({"this"}) K> keySet() {
       return AbstractMapBasedMultimap.this.keySet();
     }
 
@@ -1510,13 +1511,13 @@ public Comparator<? super K> comparator() {
 
     @Override
     @ParametricNullness
-    public K firstKey() {
+    public @KeyFor("this") K firstKey() {
       return sortedMap().firstKey();
     }
 
     @Override
     @ParametricNullness
-    public K lastKey() {
+    public @KeyFor("this") K lastKey() {
       return sortedMap().lastKey();
     }
 
@@ -1541,7 +1542,7 @@ public SortedMap<K, Collection<V>> tailMap(@ParametricNullness K fromKey) {
     // returns a SortedSet, even though returning a Set would be sufficient to
     // satisfy the SortedMap.keySet() interface
     @Override
-    public SortedSet<K> keySet() {
+    public SortedSet<@KeyFor({"this"}) K> keySet() {
       SortedSet<K> result = sortedKeySet;
       return (result == null) ? sortedKeySet = createKeySet() : result;
     }
@@ -1659,7 +1660,7 @@ public NavigableMap<K, Collection<V>> descendingMap() {
     }
 
     @Override
-    public NavigableSet<K> keySet() {
+    public NavigableSet<@KeyFor({"this"}) K> keySet() {
       return (NavigableSet<K>) super.keySet();
     }
 
@@ -1669,12 +1670,12 @@ NavigableSet<K> createKeySet() {
     }
 
     @Override
-    public NavigableSet<K> navigableKeySet() {
+    public NavigableSet<@KeyFor({"this"}) K> navigableKeySet() {
       return keySet();
     }
 
     @Override
-    public NavigableSet<K> descendingKeySet() {
+    public NavigableSet<@KeyFor({"this"}) K> descendingKeySet() {
       return descendingMap().navigableKeySet();
     }
 
diff --git a/guava/src/com/google/common/collect/AbstractMapBasedMultiset.java b/guava/src/com/google/common/collect/AbstractMapBasedMultiset.java
index b754e864e697..629816124d93 100644
--- a/guava/src/com/google/common/collect/AbstractMapBasedMultiset.java
+++ b/guava/src/com/google/common/collect/AbstractMapBasedMultiset.java
@@ -36,7 +36,9 @@
 import java.util.Set;
 import java.util.function.ObjIntConsumer;
 import javax.annotation.CheckForNull;
+import org.checkerframework.checker.index.qual.NonNegative;
 import org.checkerframework.checker.nullness.qual.Nullable;
+import org.checkerframework.checker.signedness.qual.UnknownSignedness;
 import org.checkerframework.dataflow.qual.Pure;
 import org.checkerframework.dataflow.qual.SideEffectFree;
 import org.checkerframework.framework.qual.AnnotatedFor;
@@ -254,7 +256,7 @@ public void remove() {
   }
 
   @Override
-  public int count(@CheckForNull Object element) {
+  public @NonNegative int count(@CheckForNull @UnknownSignedness Object element) {
     Count frequency = Maps.safeGet(backingMap, element);
     return (frequency == null) ? 0 : frequency.get();
   }
diff --git a/guava/src/com/google/common/collect/AbstractMultimap.java b/guava/src/com/google/common/collect/AbstractMultimap.java
index a86679037683..933a4a0bd374 100644
--- a/guava/src/com/google/common/collect/AbstractMultimap.java
+++ b/guava/src/com/google/common/collect/AbstractMultimap.java
@@ -55,7 +55,7 @@ public boolean isEmpty() {
 
   @Pure
   @Override
-  public boolean containsValue(@CheckForNull Object value) {
+  public boolean containsValue(@CheckForNull @UnknownSignedness Object value) {
     for (Collection<V> collection : asMap().values()) {
       if (collection.contains(value)) {
         return true;
diff --git a/guava/src/com/google/common/collect/AbstractNavigableMap.java b/guava/src/com/google/common/collect/AbstractNavigableMap.java
index 962105f16ea7..973b533d9dc7 100644
--- a/guava/src/com/google/common/collect/AbstractNavigableMap.java
+++ b/guava/src/com/google/common/collect/AbstractNavigableMap.java
@@ -25,6 +25,7 @@
 import java.util.Set;
 import java.util.SortedMap;
 import javax.annotation.CheckForNull;
+import org.checkerframework.checker.nullness.qual.KeyFor;
 import org.checkerframework.checker.nullness.qual.Nullable;
 import org.checkerframework.checker.signedness.qual.UnknownSignedness;
 
@@ -68,7 +69,7 @@ public Entry<K, V> pollLastEntry() {
 
   @Override
   @ParametricNullness
-  public K firstKey() {
+  public @KeyFor("this") K firstKey() {
     Entry<K, V> entry = firstEntry();
     if (entry == null) {
       throw new NoSuchElementException();
@@ -79,7 +80,7 @@ public K firstKey() {
 
   @Override
   @ParametricNullness
-  public K lastKey() {
+  public @KeyFor("this") K lastKey() {
     Entry<K, V> entry = lastEntry();
     if (entry == null) {
       throw new NoSuchElementException();
@@ -154,17 +155,17 @@ public SortedMap<K, V> tailMap(@ParametricNullness K fromKey) {
   }
 
   @Override
-  public NavigableSet<K> navigableKeySet() {
+  public NavigableSet<@KeyFor({"this"}) K> navigableKeySet() {
     return new Maps.NavigableKeySet<>(this);
   }
 
   @Override
-  public Set<K> keySet() {
+  public Set<@KeyFor({"this"}) K> keySet() {
     return navigableKeySet();
   }
 
   @Override
-  public NavigableSet<K> descendingKeySet() {
+  public NavigableSet<@KeyFor({"this"}) K> descendingKeySet() {
     return descendingMap().navigableKeySet();
   }
 
diff --git a/guava/src/com/google/common/collect/AbstractSortedKeySortedSetMultimap.java b/guava/src/com/google/common/collect/AbstractSortedKeySortedSetMultimap.java
index 676936f0578e..c2a0d06bd96b 100644
--- a/guava/src/com/google/common/collect/AbstractSortedKeySortedSetMultimap.java
+++ b/guava/src/com/google/common/collect/AbstractSortedKeySortedSetMultimap.java
@@ -21,6 +21,7 @@
 import java.util.Set;
 import java.util.SortedMap;
 import java.util.SortedSet;
+import org.checkerframework.checker.nullness.qual.KeyFor;
 import org.checkerframework.checker.nullness.qual.Nullable;
 
 /**
diff --git a/guava/src/com/google/common/collect/AbstractTable.java b/guava/src/com/google/common/collect/AbstractTable.java
index 8b4cc00468e7..934a6adb6c3c 100644
--- a/guava/src/com/google/common/collect/AbstractTable.java
+++ b/guava/src/com/google/common/collect/AbstractTable.java
@@ -61,7 +61,7 @@ public Set<C> columnKeySet() {
   }
 
   @Override
-  public boolean containsValue(@CheckForNull Object value) {
+  public boolean containsValue(@CheckForNull @UnknownSignedness Object value) {
     for (Map<C, V> row : rowMap().values()) {
       if (row.containsValue(value)) {
         return true;
diff --git a/guava/src/com/google/common/collect/ArrayListMultimap.java b/guava/src/com/google/common/collect/ArrayListMultimap.java
index 67e33bbabaef..524fb40e9280 100644
--- a/guava/src/com/google/common/collect/ArrayListMultimap.java
+++ b/guava/src/com/google/common/collect/ArrayListMultimap.java
@@ -30,6 +30,7 @@
 import java.util.List;
 import java.util.Map;
 import org.checkerframework.checker.nullness.qual.Nullable;
+import org.checkerframework.checker.signedness.qual.UnknownSignedness;
 import org.checkerframework.dataflow.qual.Pure;
 import org.checkerframework.framework.qual.AnnotatedFor;
 
@@ -180,10 +181,10 @@ private void readObject(ObjectInputStream stream) throws IOException, ClassNotFo
 public boolean containsEntry(@Nullable Object arg0, @Nullable Object arg1) { return super.containsEntry(arg0, arg1); }
 
 @Override
-public boolean containsKey(@Nullable Object arg0) { return super.containsKey(arg0); }
+public boolean containsKey(@Nullable @UnknownSignedness Object arg0) { return super.containsKey(arg0); }
 
 @Override
-public boolean containsValue(@Nullable Object arg0) { return super.containsValue(arg0); }
+public boolean containsValue(@Nullable @UnknownSignedness Object arg0) { return super.containsValue(arg0); }
 
 @Override
 public boolean equals(@Nullable Object arg0) { return super.equals(arg0); }
diff --git a/guava/src/com/google/common/collect/ArrayTable.java b/guava/src/com/google/common/collect/ArrayTable.java
index 1fce76244954..34c7dc758f33 100644
--- a/guava/src/com/google/common/collect/ArrayTable.java
+++ b/guava/src/com/google/common/collect/ArrayTable.java
@@ -38,7 +38,9 @@
 import java.util.Set;
 import java.util.Spliterator;
 import javax.annotation.CheckForNull;
+import org.checkerframework.checker.nullness.qual.KeyFor;
 import org.checkerframework.checker.nullness.qual.Nullable;
+import org.checkerframework.checker.signedness.qual.UnknownSignedness;
 
 /**
  * Fixed-size {@link Table} implementation backed by a two-dimensional array.
@@ -197,7 +199,7 @@ private ArrayMap(ImmutableMap<K, Integer> keyIndex) {
     }
 
     @Override
-    public Set<K> keySet() {
+    public Set<@KeyFor({"this"}) K> keySet() {
       return keyIndex.keySet();
     }
 
@@ -263,13 +265,13 @@ Spliterator<Entry<K, V>> entrySpliterator() {
     // TODO(lowasser): consider an optimized values() implementation
 
     @Override
-    public boolean containsKey(@CheckForNull Object key) {
+    public boolean containsKey(@CheckForNull @UnknownSignedness Object key) {
       return keyIndex.containsKey(key);
     }
 
     @CheckForNull
     @Override
-    public V get(@CheckForNull Object key) {
+    public V get(@CheckForNull @UnknownSignedness Object key) {
       Integer index = keyIndex.get(key);
       if (index == null) {
         return null;
@@ -291,7 +293,7 @@ public V put(K key, @ParametricNullness V value) {
 
     @Override
     @CheckForNull
-    public V remove(@CheckForNull Object key) {
+    public V remove(@CheckForNull @UnknownSignedness Object key) {
       throw new UnsupportedOperationException();
     }
 
@@ -429,7 +431,7 @@ public boolean containsRow(@CheckForNull Object rowKey) {
   }
 
   @Override
-  public boolean containsValue(@CheckForNull Object value) {
+  public boolean containsValue(@CheckForNull @UnknownSignedness Object value) {
     for (@Nullable V[] row : array) {
       for (V element : row) {
         if (Objects.equal(value, element)) {
diff --git a/guava/src/com/google/common/collect/CollectPreconditions.java b/guava/src/com/google/common/collect/CollectPreconditions.java
index c649b03233e3..38ebfe94ab8e 100644
--- a/guava/src/com/google/common/collect/CollectPreconditions.java
+++ b/guava/src/com/google/common/collect/CollectPreconditions.java
@@ -20,13 +20,16 @@
 
 import com.google.common.annotations.GwtCompatible;
 import com.google.errorprone.annotations.CanIgnoreReturnValue;
+import org.checkerframework.checker.index.qual.NonNegative;
+import org.checkerframework.checker.index.qual.Positive;
+import org.checkerframework.checker.signedness.qual.UnknownSignedness;
 
 /** Precondition checks useful in collection implementations. */
 @GwtCompatible
 @ElementTypesAreNonnullByDefault
 final class CollectPreconditions {
 
-  static void checkEntryNotNull(Object key, Object value) {
+  static void checkEntryNotNull(@UnknownSignedness Object key, @UnknownSignedness Object value) {
     if (key == null) {
       throw new NullPointerException("null key in entry: null=" + value);
     } else if (value == null) {
@@ -35,7 +38,7 @@ static void checkEntryNotNull(Object key, Object value) {
   }
 
   @CanIgnoreReturnValue
-  static int checkNonnegative(int value, String name) {
+  static int checkNonnegative(@NonNegative int value, String name) {
     if (value < 0) {
       throw new IllegalArgumentException(name + " cannot be negative but was: " + value);
     }
@@ -43,14 +46,14 @@ static int checkNonnegative(int value, String name) {
   }
 
   @CanIgnoreReturnValue
-  static long checkNonnegative(long value, String name) {
+  static long checkNonnegative(@NonNegative long value, String name) {
     if (value < 0) {
       throw new IllegalArgumentException(name + " cannot be negative but was: " + value);
     }
     return value;
   }
 
-  static void checkPositive(int value, String name) {
+  static void checkPositive(@Positive int value, String name) {
     if (value <= 0) {
       throw new IllegalArgumentException(name + " must be positive but was: " + value);
     }
diff --git a/guava/src/com/google/common/collect/Collections2.java b/guava/src/com/google/common/collect/Collections2.java
index d87f94314ea3..19c3955ec2fe 100644
--- a/guava/src/com/google/common/collect/Collections2.java
+++ b/guava/src/com/google/common/collect/Collections2.java
@@ -42,6 +42,7 @@
 import org.checkerframework.checker.nullness.qual.Nullable;
 import org.checkerframework.checker.nullness.qual.PolyNull;
 import org.checkerframework.checker.signedness.qual.PolySigned;
+import org.checkerframework.checker.signedness.qual.Signed;
 import org.checkerframework.checker.signedness.qual.UnknownSignedness;
 import org.checkerframework.dataflow.qual.Pure;
 import org.checkerframework.framework.qual.AnnotatedFor;
@@ -107,7 +108,7 @@ private Collections2() {}
    * Delegates to {@link Collection#contains}. Returns {@code false} if the {@code contains} method
    * throws a {@code ClassCastException} or {@code NullPointerException}.
    */
-  static boolean safeContains(Collection<?> collection, @CheckForNull Object object) {
+  static boolean safeContains(Collection<?> collection, @CheckForNull @UnknownSignedness Object object) {
     checkNotNull(collection);
     try {
       return collection.contains(object);
@@ -247,7 +248,7 @@ public int size() {
 
     @Override
     @SuppressWarnings("nullness:return")
-    public <T extends @Nullable @UnknownSignedness Object> T[] toArray(T[] array) {
+    public <T extends @Nullable @UnknownSignedness Object> T[] toArray(@PolyNull T[] array) {
       return Lists.newArrayList(iterator()).toArray(array);
     }
 
@@ -351,7 +352,7 @@ static boolean containsAllImpl(Collection<?> self, Collection<?> c) {
   }
 
   /** An implementation of {@link Collection#toString()}. */
-  static String toStringImpl(final Collection<?> collection) {
+  static String toStringImpl(final Collection<? extends @Signed Object> collection) {
     StringBuilder sb = newStringBuilderForCollection(collection.size()).append('[');
     boolean first = true;
     for (Object o : collection) {
diff --git a/guava/src/com/google/common/collect/CompactHashMap.java b/guava/src/com/google/common/collect/CompactHashMap.java
index 454cc0cfb4c9..73a33d09cea7 100644
--- a/guava/src/com/google/common/collect/CompactHashMap.java
+++ b/guava/src/com/google/common/collect/CompactHashMap.java
@@ -51,6 +51,7 @@
 import java.util.function.BiFunction;
 import java.util.function.Consumer;
 import javax.annotation.CheckForNull;
+import org.checkerframework.checker.nullness.qual.KeyFor;
 import org.checkerframework.checker.nullness.qual.Nullable;
 import org.checkerframework.checker.nullness.qual.PolyNull;
 import org.checkerframework.checker.signedness.qual.PolySigned;
@@ -693,7 +694,7 @@ public void replaceAll(BiFunction<? super K, ? super V, ? extends V> function) {
   @CheckForNull private transient Set<K> keySetView;
 
   @Override
-  public Set<K> keySet() {
+  public Set<@KeyFor({"this"}) K> keySet() {
     return (keySetView == null) ? keySetView = createKeySet() : keySetView;
   }
 
@@ -803,7 +804,7 @@ public void forEach(BiConsumer<? super K, ? super V> action) {
   @CheckForNull private transient Set<Entry<K, V>> entrySetView;
 
   @Override
-  public Set<Entry<K, V>> entrySet() {
+  public Set<Entry<@KeyFor({"this"}) K, V>> entrySet() {
     return (entrySetView == null) ? entrySetView = createEntrySet() : entrySetView;
   }
 
diff --git a/guava/src/com/google/common/collect/CompactHashSet.java b/guava/src/com/google/common/collect/CompactHashSet.java
index ff74fd3131b6..5b0c11f4566f 100644
--- a/guava/src/com/google/common/collect/CompactHashSet.java
+++ b/guava/src/com/google/common/collect/CompactHashSet.java
@@ -681,7 +681,6 @@ public void trimToSize() {
   }
 
   @Override
-  @SuppressWarnings("signedness:argument")
   public void clear() {
     if (needsAllocArrays()) {
       return;
diff --git a/guava/src/com/google/common/collect/CompactLinkedHashMap.java b/guava/src/com/google/common/collect/CompactLinkedHashMap.java
index 00926dabe9c8..cd7edf5b33d6 100644
--- a/guava/src/com/google/common/collect/CompactLinkedHashMap.java
+++ b/guava/src/com/google/common/collect/CompactLinkedHashMap.java
@@ -32,6 +32,9 @@
 import javax.annotation.CheckForNull;
 import org.checkerframework.checker.nullness.qual.Nullable;
 import org.checkerframework.checker.nullness.qual.PolyNull;
+import org.checkerframework.checker.signedness.qual.PolySigned;
+import org.checkerframework.checker.signedness.qual.UnknownSignedness;
+import org.checkerframework.framework.qual.CFComment;
 
 /**
  * CompactLinkedHashMap is an implementation of a Map with insertion or LRU iteration order,
@@ -244,14 +247,15 @@ public Spliterator<Entry<K, V>> spliterator() {
   Set<K> createKeySet() {
     @WeakOuter
     class KeySetImpl extends KeySetView {
+      @CFComment("signedness: is same as K, which this method doesn't know")
       @Override
-      public @PolyNull Object[] toArray() {
+      public @PolyNull @PolySigned Object[] toArray() {
         return ObjectArrays.toArrayImpl(this);
       }
 
       @Override
       @SuppressWarnings("nullness") // b/192354773 in our checker affects toArray declarations
-      public <T extends @Nullable Object> T[] toArray(T[] a) {
+      public <T extends @Nullable @UnknownSignedness Object> T[] toArray(T[] a) {
         return ObjectArrays.toArrayImpl(this, a);
       }
 
@@ -267,14 +271,15 @@ public Spliterator<K> spliterator() {
   Collection<V> createValues() {
     @WeakOuter
     class ValuesImpl extends ValuesView {
+      @CFComment("signedness: is same as V, which this method doesn't know")
       @Override
-      public @PolyNull Object[] toArray() {
+      public @PolyNull @PolySigned Object[] toArray() {
         return ObjectArrays.toArrayImpl(this);
       }
 
       @Override
       @SuppressWarnings("nullness") // b/192354773 in our checker affects toArray declarations
-      public <T extends @Nullable Object> T[] toArray(T[] a) {
+      public <T extends @Nullable @UnknownSignedness Object> T[] toArray(T[] a) {
         return ObjectArrays.toArrayImpl(this, a);
       }
 
diff --git a/guava/src/com/google/common/collect/CompactLinkedHashSet.java b/guava/src/com/google/common/collect/CompactLinkedHashSet.java
index 05a4e3e60961..d3d7b7cb5174 100644
--- a/guava/src/com/google/common/collect/CompactLinkedHashSet.java
+++ b/guava/src/com/google/common/collect/CompactLinkedHashSet.java
@@ -29,6 +29,8 @@
 import javax.annotation.CheckForNull;
 import org.checkerframework.checker.nullness.qual.Nullable;
 import org.checkerframework.checker.nullness.qual.PolyNull;
+import org.checkerframework.checker.signedness.qual.PolySigned;
+import org.checkerframework.checker.signedness.qual.UnknownSignedness;
 
 /**
  * CompactLinkedHashSet is an implementation of a Set, which a predictable iteration order that
@@ -234,13 +236,13 @@ int adjustAfterRemove(int indexBeforeRemove, int indexRemoved) {
   }
 
   @Override
-  public @PolyNull Object[] toArray() {
+  public @PolyNull @PolySigned Object[] toArray(CompactLinkedHashSet<@PolyNull @PolySigned E> this) {
     return ObjectArrays.toArrayImpl(this);
   }
 
   @Override
   @SuppressWarnings("nullness") // b/192354773 in our checker affects toArray declarations
-  public <T extends @Nullable Object> T[] toArray(T[] a) {
+  public <T extends @Nullable @UnknownSignedness Object> T[] toArray(T[] a) {
     return ObjectArrays.toArrayImpl(this, a);
   }
 
diff --git a/guava/src/com/google/common/collect/ConcurrentHashMultiset.java b/guava/src/com/google/common/collect/ConcurrentHashMultiset.java
index 05db19689fb5..4f4761454f34 100644
--- a/guava/src/com/google/common/collect/ConcurrentHashMultiset.java
+++ b/guava/src/com/google/common/collect/ConcurrentHashMultiset.java
@@ -42,10 +42,15 @@
 import java.util.concurrent.ConcurrentMap;
 import java.util.concurrent.atomic.AtomicInteger;
 import javax.annotation.CheckForNull;
+import org.checkerframework.checker.index.qual.NonNegative;
 import org.checkerframework.checker.nullness.qual.Nullable;
+import org.checkerframework.checker.nullness.qual.PolyNull;
+import org.checkerframework.checker.signedness.qual.PolySigned;
+import org.checkerframework.checker.signedness.qual.UnknownSignedness;
 import org.checkerframework.dataflow.qual.Pure;
 import org.checkerframework.dataflow.qual.SideEffectFree;
 import org.checkerframework.framework.qual.AnnotatedFor;
+import org.checkerframework.framework.qual.CFComment;
 
 /**
  * A multiset that supports concurrent modifications and that provides atomic versions of most
@@ -142,7 +147,7 @@ public static <E> ConcurrentHashMultiset<E> create(ConcurrentMap<E, AtomicIntege
    * @return the nonnegative number of occurrences of the element
    */
   @Override
-  public int count(@CheckForNull Object element) {
+  public @NonNegative int count(@CheckForNull @UnknownSignedness Object element) {
     AtomicInteger existingCounter = Maps.safeGet(countMap, element);
     return (existingCounter == null) ? 0 : existingCounter.get();
   }
@@ -169,13 +174,13 @@ public int size() {
    */
 
   @Override
-  public Object[] toArray() {
+  public @PolyNull @PolySigned Object[] toArray(ConcurrentHashMultiset<@PolyNull @PolySigned E> this) {
     return snapshot().toArray();
   }
 
   @Override
   @SuppressWarnings("nullness") // b/192354773 in our checker affects toArray declarations
-  public <T extends @Nullable Object> T[] toArray(T[] array) {
+  public <T extends @Nullable @UnknownSignedness Object> T[] toArray(T[] array) {
     return snapshot().toArray(array);
   }
 
@@ -471,7 +476,7 @@ public boolean containsAll(Collection<?> collection) {
       }
 
       @Override
-      public boolean remove(@CheckForNull Object object) {
+      public boolean remove(@CheckForNull @UnknownSignedness Object object) {
         return object != null && Collections2.safeRemove(delegate, object);
       }
 
@@ -576,14 +581,15 @@ ConcurrentHashMultiset<E> multiset() {
      * answer, which ours does not.
      */
 
+    @CFComment("signedness: is same as E, which this method doesn't know")
     @Override
-    public Object[] toArray() {
+    public @PolyNull @PolySigned Object[] toArray() {
       return snapshot().toArray();
     }
 
     @Override
     @SuppressWarnings("nullness") // b/192354773 in our checker affects toArray declarations
-    public <T extends @Nullable Object> T[] toArray(T[] array) {
+    public <T extends @Nullable @UnknownSignedness Object> T[] toArray(T[] array) {
       return snapshot().toArray(array);
     }
 
@@ -608,7 +614,7 @@ private List<Multiset.Entry<E>> snapshot() {
 
   @Pure
   @Override
-  public boolean remove(@Nullable Object arg0) { return super.remove(arg0); }
+  public boolean remove(@Nullable @UnknownSignedness Object arg0) { return super.remove(arg0); }
   }
 
   /** @serialData the ConcurrentMap of elements and their counts. */
diff --git a/guava/src/com/google/common/collect/DescendingImmutableSortedMultiset.java b/guava/src/com/google/common/collect/DescendingImmutableSortedMultiset.java
index 181731cc4896..dd0a25df6c97 100644
--- a/guava/src/com/google/common/collect/DescendingImmutableSortedMultiset.java
+++ b/guava/src/com/google/common/collect/DescendingImmutableSortedMultiset.java
@@ -16,6 +16,8 @@
 
 import com.google.common.annotations.GwtIncompatible;
 import javax.annotation.CheckForNull;
+import org.checkerframework.checker.index.qual.NonNegative;
+import org.checkerframework.checker.signedness.qual.UnknownSignedness;
 
 /**
  * A descending wrapper around an {@code ImmutableSortedMultiset}
@@ -33,7 +35,7 @@ final class DescendingImmutableSortedMultiset<E> extends ImmutableSortedMultiset
   }
 
   @Override
-  public int count(@CheckForNull Object element) {
+  public @NonNegative int count(@CheckForNull @UnknownSignedness Object element) {
     return forward.count(element);
   }
 
diff --git a/guava/src/com/google/common/collect/DescendingMultiset.java b/guava/src/com/google/common/collect/DescendingMultiset.java
index bad3cf09e841..6481eb06305e 100644
--- a/guava/src/com/google/common/collect/DescendingMultiset.java
+++ b/guava/src/com/google/common/collect/DescendingMultiset.java
@@ -25,6 +25,7 @@
 import javax.annotation.CheckForNull;
 import org.checkerframework.checker.nullness.qual.Nullable;
 import org.checkerframework.checker.nullness.qual.PolyNull;
+import org.checkerframework.checker.signedness.qual.PolySigned;
 
 /**
  * A skeleton implementation of a descending multiset. Only needs {@code forwardMultiset()} and
@@ -152,7 +153,7 @@ public Iterator<E> iterator() {
   }
 
   @Override
-  public @PolyNull Object[] toArray() {
+  public @PolyNull @PolySigned Object[] toArray(DescendingMultiset<@PolyNull @PolySigned E> this) {
     return standardToArray();
   }
 
diff --git a/guava/src/com/google/common/collect/EnumBiMap.java b/guava/src/com/google/common/collect/EnumBiMap.java
index 858d925fbfac..7eff19d7c977 100644
--- a/guava/src/com/google/common/collect/EnumBiMap.java
+++ b/guava/src/com/google/common/collect/EnumBiMap.java
@@ -27,6 +27,7 @@
 import java.util.EnumMap;
 import java.util.Map;
 import org.checkerframework.checker.nullness.qual.Nullable;
+import org.checkerframework.checker.signedness.qual.UnknownSignedness;
 import org.checkerframework.dataflow.qual.Pure;
 import org.checkerframework.framework.qual.AnnotatedFor;
 
@@ -145,8 +146,8 @@ private void readObject(ObjectInputStream stream) throws IOException, ClassNotFo
 
 @Pure
 @Override
-public boolean containsValue(@Nullable Object arg0) { return super.containsValue(arg0); }
+public boolean containsValue(@Nullable @UnknownSignedness Object arg0) { return super.containsValue(arg0); }
 
 @Override
-public @Nullable V remove(@Nullable Object arg0) { return super.remove(arg0); }
+public @Nullable V remove(@Nullable @UnknownSignedness Object arg0) { return super.remove(arg0); }
 }
diff --git a/guava/src/com/google/common/collect/EnumHashBiMap.java b/guava/src/com/google/common/collect/EnumHashBiMap.java
index ef791afa2994..960575542679 100644
--- a/guava/src/com/google/common/collect/EnumHashBiMap.java
+++ b/guava/src/com/google/common/collect/EnumHashBiMap.java
@@ -29,6 +29,7 @@
 import java.util.Map;
 import javax.annotation.CheckForNull;
 import org.checkerframework.checker.nullness.qual.Nullable;
+import org.checkerframework.checker.signedness.qual.UnknownSignedness;
 import org.checkerframework.dataflow.qual.Pure;
 import org.checkerframework.framework.qual.AnnotatedFor;
 
@@ -140,5 +141,5 @@ private void readObject(ObjectInputStream stream) throws IOException, ClassNotFo
 
 @Pure
 @Override
-public boolean containsValue(@Nullable Object arg0) { return super.containsValue(arg0); }
+public boolean containsValue(@Nullable @UnknownSignedness Object arg0) { return super.containsValue(arg0); }
 }
diff --git a/guava/src/com/google/common/collect/EnumMultiset.java b/guava/src/com/google/common/collect/EnumMultiset.java
index 623fed762782..7421f222c48c 100644
--- a/guava/src/com/google/common/collect/EnumMultiset.java
+++ b/guava/src/com/google/common/collect/EnumMultiset.java
@@ -33,7 +33,9 @@
 import java.util.NoSuchElementException;
 import java.util.function.ObjIntConsumer;
 import javax.annotation.CheckForNull;
+import org.checkerframework.checker.index.qual.NonNegative;
 import org.checkerframework.checker.nullness.qual.Nullable;
+import org.checkerframework.checker.signedness.qual.UnknownSignedness;
 import org.checkerframework.dataflow.qual.Pure;
 import org.checkerframework.framework.qual.AnnotatedFor;
 
@@ -130,7 +132,7 @@ public int size() {
   }
 
   @Override
-  public int count(@CheckForNull Object element) {
+  public @NonNegative int count(@CheckForNull @UnknownSignedness Object element) {
     // isActuallyE checks for null, but we check explicitly to help nullness checkers.
     if (element == null || !isActuallyE(element)) {
       return 0;
diff --git a/guava/src/com/google/common/collect/EvictingQueue.java b/guava/src/com/google/common/collect/EvictingQueue.java
index 5667dfa8c054..0932a44ca95f 100644
--- a/guava/src/com/google/common/collect/EvictingQueue.java
+++ b/guava/src/com/google/common/collect/EvictingQueue.java
@@ -27,6 +27,8 @@
 import java.util.ArrayDeque;
 import java.util.Collection;
 import java.util.Queue;
+import org.checkerframework.checker.nullness.qual.PolyNull;
+import org.checkerframework.checker.signedness.qual.PolySigned;
 
 /**
  * A non-blocking queue which automatically evicts elements from the head of the queue when
@@ -127,7 +129,7 @@ public boolean addAll(Collection<? extends E> collection) {
   }
 
   @Override
-  public Object[] toArray() {
+  public @PolyNull @PolySigned Object[] toArray(EvictingQueue<@PolyNull @PolySigned E> this) {
     /*
      * If we could, we'd declare the no-arg `Collection.toArray()` to return "Object[] but elements
      * have the same nullness as E." Since we can't, we declare it to return nullable elements, and
diff --git a/guava/src/com/google/common/collect/FilteredEntryMultimap.java b/guava/src/com/google/common/collect/FilteredEntryMultimap.java
index de946a215f42..9165711f059f 100644
--- a/guava/src/com/google/common/collect/FilteredEntryMultimap.java
+++ b/guava/src/com/google/common/collect/FilteredEntryMultimap.java
@@ -35,6 +35,7 @@
 import java.util.Set;
 import javax.annotation.CheckForNull;
 import org.checkerframework.checker.nullness.qual.Nullable;
+import org.checkerframework.checker.signedness.qual.UnknownSignedness;
 
 /**
  * Implementation of {@link Multimaps#filterEntries(Multimap, Predicate)}.
@@ -96,7 +97,7 @@ public boolean apply(@ParametricNullness V value) {
   }
 
   @Override
-  public boolean containsKey(@CheckForNull Object key) {
+  public boolean containsKey(@CheckForNull @UnknownSignedness Object key) {
     return asMap().get(key) != null;
   }
 
@@ -169,7 +170,7 @@ boolean removeEntriesIf(Predicate<? super Entry<K, Collection<V>>> predicate) {
   @WeakOuter
   class AsMap extends ViewCachingAbstractMap<K, Collection<V>> {
     @Override
-    public boolean containsKey(@CheckForNull Object key) {
+    public boolean containsKey(@CheckForNull @UnknownSignedness Object key) {
       return get(key) != null;
     }
 
@@ -237,7 +238,7 @@ public boolean retainAll(Collection<?> c) {
         }
 
         @Override
-        public boolean remove(@CheckForNull Object o) {
+        public boolean remove(@CheckForNull @UnknownSignedness Object o) {
           return AsMap.this.remove(o) != null;
         }
       }
@@ -303,7 +304,7 @@ class ValuesImpl extends Maps.Values<K, Collection<V>> {
         }
 
         @Override
-        public boolean remove(@CheckForNull Object o) {
+        public boolean remove(@CheckForNull @UnknownSignedness Object o) {
           if (o instanceof Collection) {
             Collection<?> c = (Collection<?>) o;
             Iterator<Entry<K, Collection<V>>> entryIterator =
diff --git a/guava/src/com/google/common/collect/FilteredKeyMultimap.java b/guava/src/com/google/common/collect/FilteredKeyMultimap.java
index 68fad75b1445..0351fdcc0f78 100644
--- a/guava/src/com/google/common/collect/FilteredKeyMultimap.java
+++ b/guava/src/com/google/common/collect/FilteredKeyMultimap.java
@@ -32,6 +32,7 @@
 import java.util.Set;
 import javax.annotation.CheckForNull;
 import org.checkerframework.checker.nullness.qual.Nullable;
+import org.checkerframework.checker.signedness.qual.UnknownSignedness;
 
 /**
  * Implementation of {@link Multimaps#filterKeys(Multimap, Predicate)}.
@@ -70,7 +71,7 @@ public int size() {
   }
 
   @Override
-  public boolean containsKey(@CheckForNull Object key) {
+  public boolean containsKey(@CheckForNull @UnknownSignedness Object key) {
     if (unfiltered.containsKey(key)) {
       @SuppressWarnings("unchecked") // k is equal to a K, if not one itself
       K k = (K) key;
@@ -197,7 +198,7 @@ protected Collection<Entry<K, V>> delegate() {
 
     @Override
     @SuppressWarnings("unchecked")
-    public boolean remove(@CheckForNull Object o) {
+    public boolean remove(@CheckForNull @UnknownSignedness Object o) {
       if (o instanceof Entry) {
         Entry<?, ?> entry = (Entry<?, ?>) o;
         if (unfiltered.containsKey(entry.getKey())
diff --git a/guava/src/com/google/common/collect/FilteredMultimapValues.java b/guava/src/com/google/common/collect/FilteredMultimapValues.java
index ecbfab2a1d11..89480018dea1 100644
--- a/guava/src/com/google/common/collect/FilteredMultimapValues.java
+++ b/guava/src/com/google/common/collect/FilteredMultimapValues.java
@@ -27,6 +27,7 @@
 import java.util.Map.Entry;
 import javax.annotation.CheckForNull;
 import org.checkerframework.checker.nullness.qual.Nullable;
+import org.checkerframework.checker.signedness.qual.UnknownSignedness;
 
 /**
  * Implementation for {@link FilteredMultimap#values()}.
@@ -59,7 +60,7 @@ public int size() {
   }
 
   @Override
-  public boolean remove(@CheckForNull Object o) {
+  public boolean remove(@CheckForNull @UnknownSignedness Object o) {
     Predicate<? super Entry<K, V>> entryPredicate = multimap.entryPredicate();
     for (Iterator<Entry<K, V>> unfilteredItr = multimap.unfiltered().entries().iterator();
         unfilteredItr.hasNext(); ) {
diff --git a/guava/src/com/google/common/collect/ForwardingCollection.java b/guava/src/com/google/common/collect/ForwardingCollection.java
index 55f8c7651fb3..80eeb3cab410 100644
--- a/guava/src/com/google/common/collect/ForwardingCollection.java
+++ b/guava/src/com/google/common/collect/ForwardingCollection.java
@@ -139,7 +139,7 @@ public void clear() {
   @CanIgnoreReturnValue
   @Override
   @SuppressWarnings("nullness:return")
-  public <T extends @Nullable @UnknownSignedness Object> T[] toArray(T[] array) {
+  public <T extends @Nullable @UnknownSignedness Object> T[] toArray(@PolyNull T[] array) {
     return delegate().toArray(array);
   }
 
diff --git a/guava/src/com/google/common/collect/ForwardingMap.java b/guava/src/com/google/common/collect/ForwardingMap.java
index 73856b92746c..30715bf76b4a 100644
--- a/guava/src/com/google/common/collect/ForwardingMap.java
+++ b/guava/src/com/google/common/collect/ForwardingMap.java
@@ -25,6 +25,7 @@
 import java.util.Map;
 import java.util.Set;
 import javax.annotation.CheckForNull;
+import org.checkerframework.checker.nullness.qual.KeyFor;
 import org.checkerframework.checker.nullness.qual.Nullable;
 import org.checkerframework.checker.signedness.qual.UnknownSignedness;
 import org.checkerframework.dataflow.qual.Pure;
@@ -133,7 +134,7 @@ public void putAll(Map<? extends K, ? extends V> map) {
 
   @SideEffectFree
   @Override
-  public Set<K> keySet() {
+  public Set<@KeyFor({"this"}) K> keySet() {
     return delegate().keySet();
   }
 
@@ -145,7 +146,7 @@ public Collection<V> values() {
 
   @SideEffectFree
   @Override
-  public Set<Entry<K, V>> entrySet() {
+  public Set<Entry<@KeyFor({"this"}) K, V>> entrySet() {
     return delegate().entrySet();
   }
 
diff --git a/guava/src/com/google/common/collect/ForwardingMultimap.java b/guava/src/com/google/common/collect/ForwardingMultimap.java
index cd29727fbe8c..a72f94b74f44 100644
--- a/guava/src/com/google/common/collect/ForwardingMultimap.java
+++ b/guava/src/com/google/common/collect/ForwardingMultimap.java
@@ -24,6 +24,7 @@
 import java.util.Set;
 import javax.annotation.CheckForNull;
 import org.checkerframework.checker.nullness.qual.Nullable;
+import org.checkerframework.checker.signedness.qual.UnknownSignedness;
 import org.checkerframework.dataflow.qual.Pure;
 import org.checkerframework.dataflow.qual.SideEffectFree;
 import org.checkerframework.framework.qual.AnnotatedFor;
@@ -70,13 +71,13 @@ public boolean containsEntry(@CheckForNull Object key, @CheckForNull Object valu
 
   @Pure
   @Override
-  public boolean containsKey(@CheckForNull Object key) {
+  public boolean containsKey(@CheckForNull @UnknownSignedness Object key) {
     return delegate().containsKey(key);
   }
 
   @Pure
   @Override
-  public boolean containsValue(@CheckForNull Object value) {
+  public boolean containsValue(@CheckForNull @UnknownSignedness Object value) {
     return delegate().containsValue(value);
   }
 
diff --git a/guava/src/com/google/common/collect/ForwardingMultiset.java b/guava/src/com/google/common/collect/ForwardingMultiset.java
index 5d6a7d04dbd3..85680eeb50ae 100644
--- a/guava/src/com/google/common/collect/ForwardingMultiset.java
+++ b/guava/src/com/google/common/collect/ForwardingMultiset.java
@@ -24,6 +24,7 @@
 import java.util.Iterator;
 import java.util.Set;
 import javax.annotation.CheckForNull;
+import org.checkerframework.checker.index.qual.NonNegative;
 import org.checkerframework.checker.nullness.qual.Nullable;
 import org.checkerframework.checker.signedness.qual.UnknownSignedness;
 import org.checkerframework.dataflow.qual.Pure;
@@ -65,7 +66,7 @@ protected ForwardingMultiset() {}
   protected abstract Multiset<E> delegate();
 
   @Override
-  public int count(@CheckForNull Object element) {
+  public @NonNegative int count(@CheckForNull @UnknownSignedness Object element) {
     return delegate().count(element);
   }
 
diff --git a/guava/src/com/google/common/collect/ForwardingNavigableMap.java b/guava/src/com/google/common/collect/ForwardingNavigableMap.java
index c32468da1d21..f54ac5bf9554 100644
--- a/guava/src/com/google/common/collect/ForwardingNavigableMap.java
+++ b/guava/src/com/google/common/collect/ForwardingNavigableMap.java
@@ -27,6 +27,7 @@
 import java.util.SortedMap;
 import java.util.function.BiFunction;
 import javax.annotation.CheckForNull;
+import org.checkerframework.checker.nullness.qual.KeyFor;
 import org.checkerframework.checker.nullness.qual.Nullable;
 
 /**
@@ -353,7 +354,7 @@ public void remove() {
   }
 
   @Override
-  public NavigableSet<K> navigableKeySet() {
+  public NavigableSet<@KeyFor({"this"}) K> navigableKeySet() {
     return delegate().navigableKeySet();
   }
 
@@ -374,7 +375,7 @@ public StandardNavigableKeySet() {
   }
 
   @Override
-  public NavigableSet<K> descendingKeySet() {
+  public NavigableSet<@KeyFor({"this"}) K> descendingKeySet() {
     return delegate().descendingKeySet();
   }
 
diff --git a/guava/src/com/google/common/collect/ForwardingSortedMap.java b/guava/src/com/google/common/collect/ForwardingSortedMap.java
index 6fe8bb2563bf..2d1b3eaa77ac 100644
--- a/guava/src/com/google/common/collect/ForwardingSortedMap.java
+++ b/guava/src/com/google/common/collect/ForwardingSortedMap.java
@@ -24,6 +24,7 @@
 import java.util.NoSuchElementException;
 import java.util.SortedMap;
 import javax.annotation.CheckForNull;
+import org.checkerframework.checker.nullness.qual.KeyFor;
 import org.checkerframework.checker.nullness.qual.Nullable;
 import org.checkerframework.dataflow.qual.SideEffectFree;
 import org.checkerframework.framework.qual.AnnotatedFor;
@@ -75,7 +76,7 @@ public Comparator<? super K> comparator() {
 
   @Override
   @ParametricNullness
-  public K firstKey() {
+  public @KeyFor("this") K firstKey() {
     return delegate().firstKey();
   }
 
@@ -86,7 +87,7 @@ public SortedMap<K, V> headMap(@ParametricNullness K toKey) {
 
   @Override
   @ParametricNullness
-  public K lastKey() {
+  public @KeyFor("this") K lastKey() {
     return delegate().lastKey();
   }
 
diff --git a/guava/src/com/google/common/collect/ForwardingTable.java b/guava/src/com/google/common/collect/ForwardingTable.java
index 4fcb858b725f..ef9897cd3744 100644
--- a/guava/src/com/google/common/collect/ForwardingTable.java
+++ b/guava/src/com/google/common/collect/ForwardingTable.java
@@ -23,6 +23,7 @@
 import java.util.Set;
 import javax.annotation.CheckForNull;
 import org.checkerframework.checker.nullness.qual.Nullable;
+import org.checkerframework.checker.signedness.qual.UnknownSignedness;
 
 /**
  * A table which forwards all its method calls to another table. Subclasses should override one or
@@ -84,7 +85,7 @@ public boolean containsRow(@CheckForNull Object rowKey) {
   }
 
   @Override
-  public boolean containsValue(@CheckForNull Object value) {
+  public boolean containsValue(@CheckForNull @UnknownSignedness Object value) {
     return delegate().containsValue(value);
   }
 
diff --git a/guava/src/com/google/common/collect/HashBiMap.java b/guava/src/com/google/common/collect/HashBiMap.java
index 51d6e0cf3265..f7969134ef3c 100644
--- a/guava/src/com/google/common/collect/HashBiMap.java
+++ b/guava/src/com/google/common/collect/HashBiMap.java
@@ -41,7 +41,9 @@
 import java.util.function.BiConsumer;
 import java.util.function.BiFunction;
 import javax.annotation.CheckForNull;
+import org.checkerframework.checker.nullness.qual.KeyFor;
 import org.checkerframework.checker.nullness.qual.Nullable;
+import org.checkerframework.checker.signedness.qual.UnknownSignedness;
 import org.checkerframework.dataflow.qual.Pure;
 import org.checkerframework.dataflow.qual.SideEffectFree;
 import org.checkerframework.framework.qual.AnnotatedFor;
@@ -262,7 +264,7 @@ private BiEntry<K, V> seekByValue(@CheckForNull Object value, int valueHash) {
   }
 
   @Override
-  public boolean containsKey(@CheckForNull Object key) {
+  public boolean containsKey(@CheckForNull @UnknownSignedness Object key) {
     return seekByKey(key, smearedHash(key)) != null;
   }
 
@@ -278,7 +280,7 @@ public boolean containsKey(@CheckForNull Object key) {
    */
   @Pure
   @Override
-  public boolean containsValue(@CheckForNull Object value) {
+  public boolean containsValue(@CheckForNull @UnknownSignedness Object value) {
     return seekByValue(value, smearedHash(value)) != null;
   }
 
@@ -409,7 +411,7 @@ private void rehashIfNecessary() {
   @CanIgnoreReturnValue
   @Override
   @CheckForNull
-  public V remove(@CheckForNull Object key) {
+  public V remove(@CheckForNull @UnknownSignedness Object key) {
     BiEntry<K, V> entry = seekByKey(key, smearedHash(key));
     if (entry == null) {
       return null;
@@ -481,7 +483,7 @@ public void remove() {
   }
 
   @Override
-  public Set<K> keySet() {
+  public Set<@KeyFor({"this"}) K> keySet() {
     return new KeySet();
   }
 
@@ -502,7 +504,7 @@ K output(BiEntry<K, V> entry) {
     }
 
     @Override
-    public boolean remove(@CheckForNull Object o) {
+    public boolean remove(@CheckForNull @UnknownSignedness Object o) {
       BiEntry<K, V> entry = seekByKey(o, smearedHash(o));
       if (entry == null) {
         return false;
@@ -617,7 +619,7 @@ public void clear() {
     }
 
     @Override
-    public boolean containsKey(@CheckForNull Object value) {
+    public boolean containsKey(@CheckForNull @UnknownSignedness Object value) {
       return forward().containsValue(value);
     }
 
@@ -642,7 +644,7 @@ public K forcePut(@ParametricNullness V value, @ParametricNullness K key) {
 
     @Override
     @CheckForNull
-    public K remove(@CheckForNull Object value) {
+    public K remove(@CheckForNull @UnknownSignedness Object value) {
       BiEntry<K, V> entry = seekByValue(value, smearedHash(value));
       if (entry == null) {
         return null;
@@ -660,7 +662,7 @@ public BiMap<K, V> inverse() {
     }
 
     @Override
-    public Set<V> keySet() {
+    public Set<@KeyFor({"this"}) V> keySet() {
       return new InverseKeySet();
     }
 
@@ -670,7 +672,7 @@ private final class InverseKeySet extends Maps.KeySet<V, K> {
       }
 
       @Override
-      public boolean remove(@CheckForNull Object o) {
+      public boolean remove(@CheckForNull @UnknownSignedness Object o) {
         BiEntry<K, V> entry = seekByValue(o, smearedHash(o));
         if (entry == null) {
           return false;
@@ -801,5 +803,5 @@ private void readObject(ObjectInputStream stream) throws IOException, ClassNotFo
   private static final long serialVersionUID = 0;
 
 @SideEffectFree
-public Set<Map.Entry<K, V>> entrySet() { return super.entrySet(); }
+public Set<Map.Entry<@KeyFor({"this"}) K, V>> entrySet() { return super.entrySet(); }
 }
diff --git a/guava/src/com/google/common/collect/HashMultiset.java b/guava/src/com/google/common/collect/HashMultiset.java
index 13bf36977824..7250d0da5559 100644
--- a/guava/src/com/google/common/collect/HashMultiset.java
+++ b/guava/src/com/google/common/collect/HashMultiset.java
@@ -22,7 +22,9 @@
 import java.io.ObjectInputStream;
 import java.io.ObjectOutputStream;
 import java.util.HashMap;
+import org.checkerframework.checker.index.qual.NonNegative;
 import org.checkerframework.checker.nullness.qual.Nullable;
+import org.checkerframework.checker.signedness.qual.UnknownSignedness;
 import org.checkerframework.framework.qual.AnnotatedFor;
 
 /**
@@ -100,7 +102,7 @@ private void readObject(ObjectInputStream stream) throws IOException, ClassNotFo
 public boolean contains(@Nullable Object arg0) { return super.contains(arg0); }
 
 @Override
-public int count(@Nullable Object arg0) { return super.count(arg0); }
+public @NonNegative int count(@Nullable @UnknownSignedness Object arg0) { return super.count(arg0); }
 
 @Override
 public int remove(@Nullable Object arg0, int arg1) { return super.remove(arg0, arg1); }
diff --git a/guava/src/com/google/common/collect/ImmutableBiMap.java b/guava/src/com/google/common/collect/ImmutableBiMap.java
index 64e5b77786c1..8e6799c15127 100644
--- a/guava/src/com/google/common/collect/ImmutableBiMap.java
+++ b/guava/src/com/google/common/collect/ImmutableBiMap.java
@@ -32,6 +32,7 @@
 import java.util.stream.Collector;
 import java.util.stream.Collectors;
 import javax.annotation.CheckForNull;
+import org.checkerframework.checker.nullness.qual.KeyFor;
 import org.checkerframework.checker.nullness.qual.Nullable;
 import org.checkerframework.checker.signedness.qual.UnknownSignedness;
 import org.checkerframework.dataflow.qual.SideEffectFree;
@@ -654,9 +655,9 @@ Object writeReplace() {
 
 @SideEffectFree
 @Override
-public ImmutableSet<Map.Entry<K, V>> entrySet() { return super.entrySet(); }
+public ImmutableSet<Map.Entry<@KeyFor({"this"}) K, V>> entrySet() { return super.entrySet(); }
 
 @SideEffectFree
 @Override
-public ImmutableSet<K> keySet() { return super.keySet(); }
+public ImmutableSet<@KeyFor({"this"}) K> keySet() { return super.keySet(); }
 }
diff --git a/guava/src/com/google/common/collect/ImmutableCollection.java b/guava/src/com/google/common/collect/ImmutableCollection.java
index ae6e5873a9c7..646d813ab3c4 100644
--- a/guava/src/com/google/common/collect/ImmutableCollection.java
+++ b/guava/src/com/google/common/collect/ImmutableCollection.java
@@ -215,7 +215,7 @@ public Spliterator<E> spliterator() {
    * nullness perspective. The signature below at least has the virtue of being relatively simple.
    */
   @SuppressWarnings({"nullness:return", "nullness:assignment"})
-  public final <T extends @Nullable @UnknownSignedness Object> T[] toArray(T[] other) {
+  public final <T extends @Nullable @UnknownSignedness Object> T[] toArray(@PolyNull T[] other) {
     checkNotNull(other);
     int size = size();
 
diff --git a/guava/src/com/google/common/collect/ImmutableEnumMap.java b/guava/src/com/google/common/collect/ImmutableEnumMap.java
index d1e10f97d0b9..dceddb34ed20 100644
--- a/guava/src/com/google/common/collect/ImmutableEnumMap.java
+++ b/guava/src/com/google/common/collect/ImmutableEnumMap.java
@@ -25,6 +25,7 @@
 import java.util.Spliterator;
 import java.util.function.BiConsumer;
 import javax.annotation.CheckForNull;
+import org.checkerframework.checker.signedness.qual.UnknownSignedness;
 
 /**
  * Implementation of {@link ImmutableMap} backed by a non-empty {@link java.util.EnumMap}.
@@ -70,7 +71,7 @@ public int size() {
   }
 
   @Override
-  public boolean containsKey(@CheckForNull Object key) {
+  public boolean containsKey(@CheckForNull @UnknownSignedness Object key) {
     return delegate.containsKey(key);
   }
 
diff --git a/guava/src/com/google/common/collect/ImmutableMap.java b/guava/src/com/google/common/collect/ImmutableMap.java
index 2664d9583017..8c6dc760a7df 100644
--- a/guava/src/com/google/common/collect/ImmutableMap.java
+++ b/guava/src/com/google/common/collect/ImmutableMap.java
@@ -51,9 +51,11 @@
 import java.util.stream.Collector;
 import java.util.stream.Collectors;
 import javax.annotation.CheckForNull;
+import org.checkerframework.checker.nullness.qual.KeyFor;
 import org.checkerframework.checker.nullness.qual.MonotonicNonNull;
 import org.checkerframework.checker.nullness.qual.NonNull;
 import org.checkerframework.checker.nullness.qual.Nullable;
+import org.checkerframework.checker.nullness.qual.PolyNull;
 import org.checkerframework.checker.signedness.qual.UnknownSignedness;
 import org.checkerframework.dataflow.qual.Pure;
 import org.checkerframework.dataflow.qual.SideEffectFree;
@@ -838,7 +840,7 @@ public final V replace(K key, V value) {
   @Deprecated
   @Override
   @DoNotCall("Always throws UnsupportedOperationException")
-  public final V computeIfAbsent(K key, Function<? super K, ? extends V> mappingFunction) {
+  public final @PolyNull V computeIfAbsent(K key, Function<? super K, ? extends @PolyNull V> mappingFunction) {
     throw new UnsupportedOperationException();
   }
 
@@ -851,8 +853,8 @@ public final V computeIfAbsent(K key, Function<? super K, ? extends V> mappingFu
   @Deprecated
   @Override
   @DoNotCall("Always throws UnsupportedOperationException")
-  public final V computeIfPresent(
-      K key, BiFunction<? super K, ? super V, ? extends V> remappingFunction) {
+  public final @PolyNull V computeIfPresent(
+      K key, BiFunction<? super K, ? super V, ? extends @PolyNull V> remappingFunction) {
     throw new UnsupportedOperationException();
   }
 
@@ -865,8 +867,8 @@ public final V computeIfPresent(
   @Deprecated
   @Override
   @DoNotCall("Always throws UnsupportedOperationException")
-  public final V compute(
-      K key, BiFunction<? super K, ? super @Nullable V, ? extends V> remappingFunction) {
+  public final @PolyNull V compute(
+      K key, BiFunction<? super K, ? super @Nullable V, ? extends @PolyNull V> remappingFunction) {
     throw new UnsupportedOperationException();
   }
 
@@ -879,8 +881,8 @@ public final V compute(
   @Deprecated
   @Override
   @DoNotCall("Always throws UnsupportedOperationException")
-  public final V merge(
-      K key, V value, BiFunction<? super V, ? super V, ? extends V> remappingFunction) {
+  public final @PolyNull V merge(
+      K key, V value, BiFunction<? super V, ? super V, ? extends @PolyNull V> remappingFunction) {
     throw new UnsupportedOperationException();
   }
 
@@ -1023,7 +1025,7 @@ public final V getOrDefault(@CheckForNull @UnknownSignedness Object key, @CheckF
    */
   @SideEffectFree
   @Override
-  public ImmutableSet<Entry<K, V>> entrySet() {
+  public ImmutableSet<Entry<@KeyFor({"this"}) K, V>> entrySet() {
     ImmutableSet<Entry<K, V>> result = entrySet;
     return (result == null) ? entrySet = createEntrySet() : result;
   }
@@ -1038,7 +1040,7 @@ public ImmutableSet<Entry<K, V>> entrySet() {
    */
   @SideEffectFree
   @Override
-  public ImmutableSet<K> keySet() {
+  public ImmutableSet<@KeyFor({"this"}) K> keySet() {
     ImmutableSet<K> result = keySet;
     return (result == null) ? keySet = createKeySet() : result;
   }
diff --git a/guava/src/com/google/common/collect/ImmutableMultimap.java b/guava/src/com/google/common/collect/ImmutableMultimap.java
index b98dc2c9fbca..98c381205e24 100644
--- a/guava/src/com/google/common/collect/ImmutableMultimap.java
+++ b/guava/src/com/google/common/collect/ImmutableMultimap.java
@@ -41,6 +41,7 @@
 import java.util.Spliterator;
 import java.util.function.BiConsumer;
 import javax.annotation.CheckForNull;
+import org.checkerframework.checker.index.qual.NonNegative;
 import org.checkerframework.checker.nullness.qual.Nullable;
 import org.checkerframework.checker.signedness.qual.UnknownSignedness;
 import org.checkerframework.dataflow.qual.Pure;
@@ -496,13 +497,13 @@ boolean isPartialView() {
 
   @Pure
   @Override
-  public boolean containsKey(@CheckForNull Object key) {
+  public boolean containsKey(@CheckForNull @UnknownSignedness Object key) {
     return map.containsKey(key);
   }
 
   @Pure
   @Override
-  public boolean containsValue(@CheckForNull Object value) {
+  public boolean containsValue(@CheckForNull @UnknownSignedness Object value) {
     return value != null && super.containsValue(value);
   }
 
@@ -667,7 +668,7 @@ public boolean contains(@CheckForNull @UnknownSignedness Object object) {
     }
 
     @Override
-    public int count(@CheckForNull Object element) {
+    public @NonNegative int count(@CheckForNull @UnknownSignedness Object element) {
       Collection<V> values = map.get(element);
       return (values == null) ? 0 : values.size();
     }
diff --git a/guava/src/com/google/common/collect/ImmutableSortedMap.java b/guava/src/com/google/common/collect/ImmutableSortedMap.java
index 1985f78d4c71..edcfcf46ba89 100644
--- a/guava/src/com/google/common/collect/ImmutableSortedMap.java
+++ b/guava/src/com/google/common/collect/ImmutableSortedMap.java
@@ -41,7 +41,9 @@
 import java.util.stream.Collector;
 import java.util.stream.Collectors;
 import javax.annotation.CheckForNull;
+import org.checkerframework.checker.nullness.qual.KeyFor;
 import org.checkerframework.checker.nullness.qual.Nullable;
+import org.checkerframework.checker.signedness.qual.UnknownSignedness;
 import org.checkerframework.dataflow.qual.Pure;
 import org.checkerframework.dataflow.qual.SideEffectFree;
 import org.checkerframework.framework.qual.AnnotatedFor;
@@ -814,7 +816,7 @@ boolean isPartialView() {
   /** Returns an immutable set of the mappings in this map, sorted by the key ordering. */
   @SideEffectFree
   @Override
-  public ImmutableSet<Entry<K, V>> entrySet() {
+  public ImmutableSet<Entry<@KeyFor({"this"}) K, V>> entrySet() {
     return super.entrySet();
   }
 
@@ -873,7 +875,7 @@ ImmutableMap<K, V> map() {
   /** Returns an immutable sorted set of the keys in this map. */
   @SideEffectFree
   @Override
-  public ImmutableSortedSet<K> keySet() {
+  public ImmutableSortedSet<@KeyFor({"this"}) K> keySet() {
     return keySet;
   }
 
@@ -909,12 +911,12 @@ public Comparator<? super K> comparator() {
   }
 
   @Override
-  public K firstKey() {
+  public @KeyFor("this") K firstKey() {
     return keySet().first();
   }
 
   @Override
-  public K lastKey() {
+  public @KeyFor("this") K lastKey() {
     return keySet().last();
   }
 
@@ -1138,12 +1140,12 @@ public ImmutableSortedMap<K, V> descendingMap() {
   }
 
   @Override
-  public ImmutableSortedSet<K> navigableKeySet() {
+  public ImmutableSortedSet<@KeyFor({"this"}) K> navigableKeySet() {
     return keySet;
   }
 
   @Override
-  public ImmutableSortedSet<K> descendingKeySet() {
+  public ImmutableSortedSet<@KeyFor({"this"}) K> descendingKeySet() {
     return keySet.descendingSet();
   }
 
@@ -1178,5 +1180,5 @@ Object writeReplace() {
   private static final long serialVersionUID = 0;
 
 @Pure
-public boolean containsValue(@Nullable Object arg0) { return super.containsValue(arg0); }
+public boolean containsValue(@Nullable @UnknownSignedness Object arg0) { return super.containsValue(arg0); }
 }
diff --git a/guava/src/com/google/common/collect/ImmutableSortedSet.java b/guava/src/com/google/common/collect/ImmutableSortedSet.java
index 844c729400e9..ab5f583e8238 100644
--- a/guava/src/com/google/common/collect/ImmutableSortedSet.java
+++ b/guava/src/com/google/common/collect/ImmutableSortedSet.java
@@ -41,6 +41,7 @@
 import java.util.stream.Collector;
 import javax.annotation.CheckForNull;
 import org.checkerframework.checker.nullness.qual.Nullable;
+import org.checkerframework.checker.signedness.qual.UnknownSignedness;
 import org.checkerframework.dataflow.qual.SideEffectFree;
 import org.checkerframework.framework.qual.AnnotatedFor;
 
@@ -580,11 +581,11 @@ public ImmutableSortedSet<E> build() {
     }
   }
 
-  int unsafeCompare(Object a, @CheckForNull Object b) {
+  int unsafeCompare(@UnknownSignedness Object a, @CheckForNull @UnknownSignedness Object b) {
     return unsafeCompare(comparator, a, b);
   }
 
-  static int unsafeCompare(Comparator<?> comparator, Object a, @CheckForNull Object b) {
+  static int unsafeCompare(Comparator<?> comparator, @UnknownSignedness Object a, @CheckForNull @UnknownSignedness Object b) {
     // Pretend the comparator can compare anything. If it turns out it can't
     // compare a and b, we should get a CCE or NPE on the subsequent line. Only methods
     // that are spec'd to throw CCE and NPE should call this.
diff --git a/guava/src/com/google/common/collect/ImmutableTable.java b/guava/src/com/google/common/collect/ImmutableTable.java
index 033c271e6f69..85f20642cb90 100644
--- a/guava/src/com/google/common/collect/ImmutableTable.java
+++ b/guava/src/com/google/common/collect/ImmutableTable.java
@@ -34,6 +34,7 @@
 import java.util.stream.Collector;
 import javax.annotation.CheckForNull;
 import org.checkerframework.checker.nullness.qual.Nullable;
+import org.checkerframework.checker.signedness.qual.UnknownSignedness;
 
 /**
  * A {@link Table} whose contents will never change, with many other important properties detailed
@@ -381,7 +382,7 @@ public boolean contains(@CheckForNull Object rowKey, @CheckForNull Object column
   }
 
   @Override
-  public boolean containsValue(@CheckForNull Object value) {
+  public boolean containsValue(@CheckForNull @UnknownSignedness Object value) {
     return values().contains(value);
   }
 
diff --git a/guava/src/com/google/common/collect/Iterators.java b/guava/src/com/google/common/collect/Iterators.java
index ea9a4193183c..039917402e49 100644
--- a/guava/src/com/google/common/collect/Iterators.java
+++ b/guava/src/com/google/common/collect/Iterators.java
@@ -49,6 +49,7 @@
 import java.util.Queue;
 import javax.annotation.CheckForNull;
 import org.checkerframework.checker.nullness.qual.Nullable;
+import org.checkerframework.checker.signedness.qual.UnknownSignedness;
 import org.checkerframework.dataflow.qual.Pure;
 import org.checkerframework.framework.qual.AnnotatedFor;
 
@@ -178,7 +179,7 @@ public static int size(Iterator<?> iterator) {
 
   /** Returns {@code true} if {@code iterator} contains {@code element}. */
   @Pure
-  public static boolean contains(Iterator<?> iterator, @CheckForNull Object element) {
+  public static boolean contains(Iterator<?> iterator, @CheckForNull @UnknownSignedness Object element) {
     if (element == null) {
       while (iterator.hasNext()) {
         if (iterator.next() == null) {
diff --git a/guava/src/com/google/common/collect/JdkBackedImmutableMultiset.java b/guava/src/com/google/common/collect/JdkBackedImmutableMultiset.java
index faf22b343121..9debeff6d22e 100644
--- a/guava/src/com/google/common/collect/JdkBackedImmutableMultiset.java
+++ b/guava/src/com/google/common/collect/JdkBackedImmutableMultiset.java
@@ -21,6 +21,8 @@
 import java.util.Collection;
 import java.util.Map;
 import javax.annotation.CheckForNull;
+import org.checkerframework.checker.index.qual.NonNegative;
+import org.checkerframework.checker.signedness.qual.UnknownSignedness;
 
 /**
  * An implementation of ImmutableMultiset backed by a JDK Map and a list of entries. Used to protect
@@ -62,7 +64,7 @@ private JdkBackedImmutableMultiset(
   }
 
   @Override
-  public int count(@CheckForNull Object element) {
+  public @NonNegative int count(@CheckForNull @UnknownSignedness Object element) {
     return delegateMap.getOrDefault(element, 0);
   }
 
diff --git a/guava/src/com/google/common/collect/LinkedHashMultimap.java b/guava/src/com/google/common/collect/LinkedHashMultimap.java
index 62b358bcadcf..5583f2844662 100644
--- a/guava/src/com/google/common/collect/LinkedHashMultimap.java
+++ b/guava/src/com/google/common/collect/LinkedHashMultimap.java
@@ -42,7 +42,9 @@
 import java.util.Spliterators;
 import java.util.function.Consumer;
 import javax.annotation.CheckForNull;
+import org.checkerframework.checker.nullness.qual.KeyFor;
 import org.checkerframework.checker.nullness.qual.Nullable;
+import org.checkerframework.checker.signedness.qual.UnknownSignedness;
 import org.checkerframework.dataflow.qual.SideEffectFree;
 import org.checkerframework.framework.qual.AnnotatedFor;
 
@@ -525,7 +527,7 @@ private void rehashIfNecessary() {
 
     @CanIgnoreReturnValue
     @Override
-    public boolean remove(@CheckForNull Object o) {
+    public boolean remove(@CheckForNull @UnknownSignedness Object o) {
       int smearedHash = Hashing.smearedHash(o);
       int bucket = smearedHash & mask();
       ValueEntry<K, V> prev = null;
diff --git a/guava/src/com/google/common/collect/LinkedHashMultiset.java b/guava/src/com/google/common/collect/LinkedHashMultiset.java
index 17f020783dfa..18192831e65c 100644
--- a/guava/src/com/google/common/collect/LinkedHashMultiset.java
+++ b/guava/src/com/google/common/collect/LinkedHashMultiset.java
@@ -23,6 +23,7 @@
 import java.io.ObjectOutputStream;
 import java.util.Collection;
 import java.util.LinkedHashMap;
+import org.checkerframework.checker.index.qual.NonNegative;
 import org.checkerframework.checker.nullness.qual.Nullable;
 import org.checkerframework.checker.signedness.qual.UnknownSignedness;
 import org.checkerframework.dataflow.qual.Pure;
@@ -112,7 +113,7 @@ private void readObject(ObjectInputStream stream) throws IOException, ClassNotFo
   public boolean contains(@Nullable @UnknownSignedness Object arg0) { return super.contains(arg0); }
 
   @Override
-  public int count(@Nullable Object arg0) { return super.count(arg0); }
+  public @NonNegative int count(@Nullable @UnknownSignedness Object arg0) { return super.count(arg0); }
 
   @Override
   public int remove(@Nullable Object arg0, int arg1) { return super.remove(arg0, arg1); }
diff --git a/guava/src/com/google/common/collect/LinkedListMultimap.java b/guava/src/com/google/common/collect/LinkedListMultimap.java
index 14daed163c6b..a2fcff1e7c60 100644
--- a/guava/src/com/google/common/collect/LinkedListMultimap.java
+++ b/guava/src/com/google/common/collect/LinkedListMultimap.java
@@ -43,6 +43,7 @@
 import java.util.function.Consumer;
 import javax.annotation.CheckForNull;
 import org.checkerframework.checker.nullness.qual.Nullable;
+import org.checkerframework.checker.signedness.qual.UnknownSignedness;
 import org.checkerframework.dataflow.qual.Pure;
 import org.checkerframework.dataflow.qual.SideEffectFree;
 import org.checkerframework.framework.qual.AnnotatedFor;
@@ -612,13 +613,13 @@ public boolean isEmpty() {
 
   @Pure
   @Override
-  public boolean containsKey(@CheckForNull Object key) {
+  public boolean containsKey(@CheckForNull @UnknownSignedness Object key) {
     return keyToKeyList.containsKey(key);
   }
 
   @Pure
   @Override
-  public boolean containsValue(@CheckForNull Object value) {
+  public boolean containsValue(@CheckForNull @UnknownSignedness Object value) {
     return values().contains(value);
   }
 
@@ -757,7 +758,7 @@ public boolean contains(@CheckForNull Object key) { // for performance
       }
 
       @Override
-      public boolean remove(@CheckForNull Object o) { // for performance
+      public boolean remove(@CheckForNull @UnknownSignedness Object o) { // for performance
         return !LinkedListMultimap.this.removeAll(o).isEmpty();
       }
     }
diff --git a/guava/src/com/google/common/collect/Lists.java b/guava/src/com/google/common/collect/Lists.java
index 9a704e003ac1..8e4983d8756a 100644
--- a/guava/src/com/google/common/collect/Lists.java
+++ b/guava/src/com/google/common/collect/Lists.java
@@ -996,7 +996,7 @@ static int hashCodeImpl(List<?> list) {
   }
 
   /** An implementation of {@link List#equals(Object)}. */
-  static boolean equalsImpl(List<?> thisList, @CheckForNull Object other) {
+  static boolean equalsImpl(List<?> thisList, @CheckForNull @UnknownSignedness Object other) {
     if (other == checkNotNull(thisList)) {
       return true;
     }
@@ -1034,7 +1034,7 @@ static boolean equalsImpl(List<?> thisList, @CheckForNull Object other) {
   }
 
   /** An implementation of {@link List#indexOf(Object)}. */
-  static int indexOfImpl(List<?> list, @CheckForNull Object element) {
+  static int indexOfImpl(List<?> list, @CheckForNull @UnknownSignedness Object element) {
     if (list instanceof RandomAccess) {
       return indexOfRandomAccess(list, element);
     } else {
@@ -1067,7 +1067,7 @@ private static int indexOfRandomAccess(List<?> list, @CheckForNull Object elemen
   }
 
   /** An implementation of {@link List#lastIndexOf(Object)}. */
-  static int lastIndexOfImpl(List<?> list, @CheckForNull Object element) {
+  static int lastIndexOfImpl(List<?> list, @CheckForNull @UnknownSignedness Object element) {
     if (list instanceof RandomAccess) {
       return lastIndexOfRandomAccess(list, element);
     } else {
diff --git a/guava/src/com/google/common/collect/MapMakerInternalMap.java b/guava/src/com/google/common/collect/MapMakerInternalMap.java
index 3725d9723b00..89e99f9d0c37 100644
--- a/guava/src/com/google/common/collect/MapMakerInternalMap.java
+++ b/guava/src/com/google/common/collect/MapMakerInternalMap.java
@@ -47,7 +47,12 @@
 import java.util.concurrent.atomic.AtomicInteger;
 import java.util.concurrent.atomic.AtomicReferenceArray;
 import java.util.concurrent.locks.ReentrantLock;
+import org.checkerframework.checker.nullness.qual.KeyFor;
 import org.checkerframework.checker.nullness.qual.Nullable;
+import org.checkerframework.checker.nullness.qual.PolyNull;
+import org.checkerframework.checker.signedness.qual.PolySigned;
+import org.checkerframework.checker.signedness.qual.UnknownSignedness;
+import org.checkerframework.framework.qual.CFComment;
 
 /**
  * The concurrent hash map implementation built by {@link MapMaker}.
@@ -1430,7 +1435,7 @@ V get(Object key, int hash) {
       }
     }
 
-    boolean containsKey(Object key, int hash) {
+    boolean containsKey(@UnknownSignedness Object key, int hash) {
       try {
         if (count != 0) { // read-volatile
           E e = getLiveEntry(key, hash);
@@ -1448,7 +1453,7 @@ boolean containsKey(Object key, int hash) {
      * MapMakerInternalMap#containsValue} directly.
      */
     @VisibleForTesting
-    boolean containsValue(Object value) {
+    boolean containsValue(@UnknownSignedness Object value) {
       try {
         if (count != 0) { // read-volatile
           AtomicReferenceArray<E> table = this.table;
@@ -2334,7 +2339,7 @@ public int size() {
   }
 
   @Override
-  public V get(@Nullable Object key) {
+  public V get(@Nullable @UnknownSignedness Object key) {
     if (key == null) {
       return null;
     }
@@ -2355,7 +2360,7 @@ E getEntry(@Nullable Object key) {
   }
 
   @Override
-  public boolean containsKey(@Nullable Object key) {
+  public boolean containsKey(@Nullable @UnknownSignedness Object key) {
     if (key == null) {
       return false;
     }
@@ -2364,7 +2369,7 @@ public boolean containsKey(@Nullable Object key) {
   }
 
   @Override
-  public boolean containsValue(@Nullable Object value) {
+  public boolean containsValue(@Nullable @UnknownSignedness Object value) {
     if (value == null) {
       return false;
     }
@@ -2428,7 +2433,7 @@ public void putAll(Map<? extends K, ? extends V> m) {
 
   @CanIgnoreReturnValue
   @Override
-  public V remove(@Nullable Object key) {
+  public V remove(@Nullable @UnknownSignedness Object key) {
     if (key == null) {
       return null;
     }
@@ -2438,7 +2443,7 @@ public V remove(@Nullable Object key) {
 
   @CanIgnoreReturnValue
   @Override
-  public boolean remove(@Nullable Object key, @Nullable Object value) {
+  public boolean remove(@Nullable @UnknownSignedness Object key, @Nullable @UnknownSignedness Object value) {
     if (key == null || value == null) {
       return false;
     }
@@ -2477,7 +2482,7 @@ public void clear() {
   transient @Nullable Set<K> keySet;
 
   @Override
-  public Set<K> keySet() {
+  public Set<@KeyFor({"this"}) K> keySet() {
     Set<K> ks = keySet;
     return (ks != null) ? ks : (keySet = new KeySet());
   }
@@ -2493,7 +2498,7 @@ public Collection<V> values() {
   transient @Nullable Set<Entry<K, V>> entrySet;
 
   @Override
-  public Set<Entry<K, V>> entrySet() {
+  public Set<Entry<@KeyFor({"this"}) K, V>> entrySet() {
     Set<Entry<K, V>> es = entrySet;
     return (es != null) ? es : (entrySet = new EntrySet());
   }
@@ -2698,12 +2703,12 @@ public boolean isEmpty() {
     }
 
     @Override
-    public boolean contains(Object o) {
+    public boolean contains(@UnknownSignedness Object o) {
       return MapMakerInternalMap.this.containsKey(o);
     }
 
     @Override
-    public boolean remove(Object o) {
+    public boolean remove(@UnknownSignedness Object o) {
       return MapMakerInternalMap.this.remove(o) != null;
     }
 
@@ -2732,7 +2737,7 @@ public boolean isEmpty() {
     }
 
     @Override
-    public boolean contains(Object o) {
+    public boolean contains(@UnknownSignedness Object o) {
       return MapMakerInternalMap.this.containsValue(o);
     }
 
@@ -2744,8 +2749,9 @@ public void clear() {
     // super.toArray() may misbehave if size() is inaccurate, at least on old versions of Android.
     // https://code.google.com/p/android/issues/detail?id=36519 / http://r.android.com/47508
 
+    @CFComment("qualifers depend on V, which this method doesn't know")
     @Override
-    public Object[] toArray() {
+    public @PolyNull @PolySigned Object[] toArray() {
       return toArrayList(this).toArray();
     }
 
@@ -2764,7 +2770,7 @@ public Iterator<Entry<K, V>> iterator() {
     }
 
     @Override
-    public boolean contains(Object o) {
+    public boolean contains(@UnknownSignedness Object o) {
       if (!(o instanceof Entry)) {
         return false;
       }
@@ -2779,7 +2785,7 @@ public boolean contains(Object o) {
     }
 
     @Override
-    public boolean remove(Object o) {
+    public boolean remove(@UnknownSignedness Object o) {
       if (!(o instanceof Entry)) {
         return false;
       }
@@ -2809,7 +2815,7 @@ private abstract static class SafeToArraySet<E> extends AbstractSet<E> {
     // https://code.google.com/p/android/issues/detail?id=36519 / http://r.android.com/47508
 
     @Override
-    public Object[] toArray() {
+    public @PolyNull @PolySigned Object[] toArray(SafeToArraySet<@PolyNull @PolySigned E> this) {
       return toArrayList(this).toArray();
     }
 
diff --git a/guava/src/com/google/common/collect/Maps.java b/guava/src/com/google/common/collect/Maps.java
index a8b1eaf72b62..d9c111bb1612 100644
--- a/guava/src/com/google/common/collect/Maps.java
+++ b/guava/src/com/google/common/collect/Maps.java
@@ -71,6 +71,7 @@
 import java.util.function.Consumer;
 import java.util.stream.Collector;
 import javax.annotation.CheckForNull;
+import org.checkerframework.checker.nullness.qual.KeyFor;
 import org.checkerframework.checker.nullness.qual.Nullable;
 import org.checkerframework.checker.nullness.qual.PolyNull;
 import org.checkerframework.checker.signedness.qual.PolySigned;
@@ -78,6 +79,7 @@
 import org.checkerframework.dataflow.qual.Pure;
 import org.checkerframework.dataflow.qual.SideEffectFree;
 import org.checkerframework.framework.qual.AnnotatedFor;
+import org.checkerframework.framework.qual.CFComment;
 
 /**
  * Static utility methods pertaining to {@link Map} instances (including instances of {@link
@@ -1035,7 +1037,7 @@ public Comparator<? super K> comparator() {
     }
 
     @Override
-    public Set<K> keySet() {
+    public Set<@KeyFor({"this"}) K> keySet() {
       return removeOnlySortedSet(backingSet());
     }
 
@@ -1056,13 +1058,13 @@ public SortedMap<K, V> tailMap(@ParametricNullness K fromKey) {
 
     @Override
     @ParametricNullness
-    public K firstKey() {
+    public @KeyFor("this") K firstKey() {
       return backingSet().first();
     }
 
     @Override
     @ParametricNullness
-    public K lastKey() {
+    public @KeyFor("this") K lastKey() {
       return backingSet().last();
     }
   }
@@ -1153,7 +1155,7 @@ Iterator<Entry<K, V>> descendingEntryIterator() {
     }
 
     @Override
-    public NavigableSet<K> navigableKeySet() {
+    public NavigableSet<@KeyFor({"this"}) K> navigableKeySet() {
       return removeOnlyNavigableSet(set);
     }
 
@@ -1556,8 +1558,10 @@ public Iterator<Entry<K, V>> iterator() {
 
     // See java.util.Collections.UnmodifiableEntrySet for details on attacks.
 
+    @CFComment({"signedness: is not applicable te `Entry` objects, which are the elements of the array",
+            "nullness: the receiver is a collection of non-null `Entry` objects"})
     @Override
-    public @PolySigned Object[] toArray() {
+    public Object[] toArray() {
       /*
        * standardToArray returns `@Nullable Object[]` rather than `Object[]` but only because it can
        * be used with collections that may contain null. This collection never contains nulls, so we
@@ -1636,6 +1640,7 @@ protected A doBackward(B b) {
       return convert(bimap.inverse(), b);
     }
 
+    @SuppressWarnings("signedness:argument")  // diagnostic output
     private static <X, Y> Y convert(BiMap<X, Y> bimap, X input) {
       Y output = bimap.get(input);
       checkArgument(output != null, "No non-null mapping present for input: %s", input);
@@ -1768,26 +1773,26 @@ public V replace(K key, V value) {
     }
 
     @Override
-    public V computeIfAbsent(
-        K key, java.util.function.Function<? super K, ? extends V> mappingFunction) {
+    public @PolyNull V computeIfAbsent(
+        K key, java.util.function.Function<? super K, ? extends @PolyNull V> mappingFunction) {
       throw new UnsupportedOperationException();
     }
 
     @Override
-    public V computeIfPresent(
-        K key, BiFunction<? super K, ? super V, ? extends V> remappingFunction) {
+    public @PolyNull V computeIfPresent(
+        K key, BiFunction<? super K, ? super V, ? extends @PolyNull V> remappingFunction) {
       throw new UnsupportedOperationException();
     }
 
     @Override
-    public V compute(
-        K key, BiFunction<? super K, ? super @Nullable V, ? extends V> remappingFunction) {
+    public @PolyNull V compute(
+        K key, BiFunction<? super K, ? super @Nullable V, ? extends @PolyNull V> remappingFunction) {
       throw new UnsupportedOperationException();
     }
 
     @Override
-    public V merge(
-        K key, V value, BiFunction<? super V, ? super V, ? extends V> remappingFunction) {
+    public @PolyNull V merge(
+        K key, V value, BiFunction<? super V, ? super V, ? extends @PolyNull V> remappingFunction) {
       throw new UnsupportedOperationException();
     }
 
@@ -2262,7 +2267,7 @@ public void clear() {
     }
 
     @Override
-    public Set<K> keySet() {
+    public Set<@KeyFor({"this"}) K> keySet() {
       return fromMap.keySet();
     }
 
@@ -2312,7 +2317,7 @@ public Comparator<? super K> comparator() {
 
     @Override
     @ParametricNullness
-    public K firstKey() {
+    public @KeyFor("this") K firstKey() {
       return fromMap().firstKey();
     }
 
@@ -2323,7 +2328,7 @@ public SortedMap<K, V2> headMap(@ParametricNullness K toKey) {
 
     @Override
     @ParametricNullness
-    public K lastKey() {
+    public @KeyFor("this") K lastKey() {
       return fromMap().lastKey();
     }
 
@@ -2361,7 +2366,7 @@ public K ceilingKey(@ParametricNullness K key) {
     }
 
     @Override
-    public NavigableSet<K> descendingKeySet() {
+    public NavigableSet<@KeyFor({"this"}) K> descendingKeySet() {
       return fromMap().descendingKeySet();
     }
 
@@ -2429,7 +2434,7 @@ public K lowerKey(@ParametricNullness K key) {
     }
 
     @Override
-    public NavigableSet<K> navigableKeySet() {
+    public NavigableSet<@KeyFor({"this"}) K> navigableKeySet() {
       return fromMap().navigableKeySet();
     }
 
@@ -3050,7 +3055,7 @@ public boolean retainAll(Collection<?> collection) {
     }
 
     @Override
-    public @Nullable @PolySigned Object[] toArray() {
+    public @PolyNull @PolySigned Object[] toArray(FilteredMapValues<@PolyNull @PolySigned K, V> this) {
       // creating an ArrayList so filtering happens once
       return Lists.newArrayList(iterator()).toArray();
     }
@@ -3232,7 +3237,7 @@ SortedMap<K, V> sortedMap() {
     }
 
     @Override
-    public SortedSet<K> keySet() {
+    public SortedSet<@KeyFor({"this"}) K> keySet() {
       return (SortedSet<K>) super.keySet();
     }
 
@@ -3286,14 +3291,14 @@ public Comparator<? super K> comparator() {
 
     @Override
     @ParametricNullness
-    public K firstKey() {
+    public @KeyFor("this") K firstKey() {
       // correctly throws NoSuchElementException when filtered map is empty.
       return keySet().iterator().next();
     }
 
     @Override
     @ParametricNullness
-    public K lastKey() {
+    public @KeyFor("this") K lastKey() {
       SortedMap<K, V> headMap = sortedMap();
       while (true) {
         // correctly throws NoSuchElementException when filtered map is empty.
@@ -3350,7 +3355,7 @@ public Comparator<? super K> comparator() {
     }
 
     @Override
-    public NavigableSet<K> navigableKeySet() {
+    public NavigableSet<@KeyFor({"this"}) K> navigableKeySet() {
       return new Maps.NavigableKeySet<K, V>(this) {
         @Override
         public boolean removeAll(Collection<?> collection) {
@@ -3423,7 +3428,7 @@ public void clear() {
     }
 
     @Override
-    public Set<Entry<K, V>> entrySet() {
+    public Set<Entry<@KeyFor({"this"}) K, V>> entrySet() {
       return filteredDelegate.entrySet();
     }
 
@@ -3681,26 +3686,26 @@ public V replace(K key, V value) {
     }
 
     @Override
-    public V computeIfAbsent(
-        K key, java.util.function.Function<? super K, ? extends V> mappingFunction) {
+    public @PolyNull V computeIfAbsent(
+        K key, java.util.function.Function<? super K, ? extends @PolyNull V> mappingFunction) {
       throw new UnsupportedOperationException();
     }
 
     @Override
-    public V computeIfPresent(
-        K key, BiFunction<? super K, ? super V, ? extends V> remappingFunction) {
+    public @PolyNull V computeIfPresent(
+        K key, BiFunction<? super K, ? super V, ? extends @PolyNull V> remappingFunction) {
       throw new UnsupportedOperationException();
     }
 
     @Override
-    public V compute(
-        K key, BiFunction<? super K, ? super @Nullable V, ? extends V> remappingFunction) {
+    public @PolyNull V compute(
+        K key, BiFunction<? super K, ? super @Nullable V, ? extends @PolyNull V> remappingFunction) {
       throw new UnsupportedOperationException();
     }
 
     @Override
-    public V merge(
-        K key, V value, BiFunction<? super V, ? super V, ? extends V> remappingFunction) {
+    public @PolyNull V merge(
+        K key, V value, BiFunction<? super V, ? super V, ? extends @PolyNull V> remappingFunction) {
       throw new UnsupportedOperationException();
     }
 
@@ -3715,17 +3720,17 @@ public NavigableMap<K, V> descendingMap() {
     }
 
     @Override
-    public Set<K> keySet() {
+    public Set<@KeyFor({"this"}) K> keySet() {
       return navigableKeySet();
     }
 
     @Override
-    public NavigableSet<K> navigableKeySet() {
+    public NavigableSet<@KeyFor({"this"}) K> navigableKeySet() {
       return Sets.unmodifiableNavigableSet(delegate.navigableKeySet());
     }
 
     @Override
-    public NavigableSet<K> descendingKeySet() {
+    public NavigableSet<@KeyFor({"this"}) K> descendingKeySet() {
       return Sets.unmodifiableNavigableSet(delegate.descendingKeySet());
     }
 
@@ -3837,7 +3842,7 @@ abstract static class ViewCachingAbstractMap<
     @CheckForNull private transient Set<Entry<K, V>> entrySet;
 
     @Override
-    public Set<Entry<K, V>> entrySet() {
+    public Set<Entry<@KeyFor({"this"}) K, V>> entrySet() {
       Set<Entry<K, V>> result = entrySet;
       return (result == null) ? entrySet = createEntrySet() : result;
     }
@@ -3845,7 +3850,7 @@ public Set<Entry<K, V>> entrySet() {
     @CheckForNull private transient Set<K> keySet;
 
     @Override
-    public Set<K> keySet() {
+    public Set<@KeyFor({"this"}) K> keySet() {
       Set<K> result = keySet;
       return (result == null) ? keySet = createKeySet() : result;
     }
@@ -3881,7 +3886,7 @@ Spliterator<Entry<K, V>> entrySpliterator() {
     }
 
     @Override
-    public Set<Entry<K, V>> entrySet() {
+    public Set<Entry<@KeyFor({"this"}) K, V>> entrySet() {
       return new EntrySet<K, V>() {
         @Override
         Map<K, V> map() {
@@ -3920,7 +3925,7 @@ public void clear() {
    * NullPointerException}.
    */
   @CheckForNull
-  static <V extends @Nullable Object> V safeGet(Map<?, V> map, @CheckForNull Object key) {
+  static <V extends @Nullable Object> V safeGet(Map<?, V> map, @CheckForNull @UnknownSignedness Object key) {
     checkNotNull(map);
     try {
       return map.get(key);
@@ -3957,12 +3962,12 @@ static boolean safeContainsKey(Map<?, ?> map, @CheckForNull Object key) {
   }
 
   /** An admittedly inefficient implementation of {@link Map#containsKey}. */
-  static boolean containsKeyImpl(Map<?, ?> map, @CheckForNull Object key) {
+  static boolean containsKeyImpl(Map<?, ?> map, @CheckForNull @UnknownSignedness Object key) {
     return Iterators.contains(keyIterator(map.entrySet().iterator()), key);
   }
 
   /** An implementation of {@link Map#containsValue}. */
-  static boolean containsValueImpl(Map<?, ?> map, @CheckForNull Object value) {
+  static boolean containsValueImpl(Map<?, ?> map, @CheckForNull @UnknownSignedness Object value) {
     return Iterators.contains(valueIterator(map.entrySet().iterator()), value);
   }
 
@@ -4007,7 +4012,7 @@ static boolean containsValueImpl(Map<?, ?> map, @CheckForNull Object value) {
   }
 
   /** An implementation of {@link Map#equals}. */
-  static boolean equalsImpl(Map<?, ?> map, @CheckForNull Object object) {
+  static boolean equalsImpl(Map<?, ?> map, @CheckForNull @UnknownSignedness Object object) {
     if (map == object) {
       return true;
     } else if (object instanceof Map) {
@@ -4440,13 +4445,13 @@ public Comparator<? super K> comparator() {
 
     @Override
     @ParametricNullness
-    public K firstKey() {
+    public @KeyFor("this") K firstKey() {
       return forward().lastKey();
     }
 
     @Override
     @ParametricNullness
-    public K lastKey() {
+    public @KeyFor("this") K lastKey() {
       return forward().firstKey();
     }
 
@@ -4530,7 +4535,7 @@ public NavigableMap<K, V> descendingMap() {
     @CheckForNull private transient Set<Entry<K, V>> entrySet;
 
     @Override
-    public Set<Entry<K, V>> entrySet() {
+    public Set<Entry<@KeyFor({"this"}) K, V>> entrySet() {
       Set<Entry<K, V>> result = entrySet;
       return (result == null) ? entrySet = createEntrySet() : result;
     }
@@ -4554,20 +4559,20 @@ public Iterator<Entry<K, V>> iterator() {
     }
 
     @Override
-    public Set<K> keySet() {
+    public Set<@KeyFor({"this"}) K> keySet() {
       return navigableKeySet();
     }
 
     @CheckForNull private transient NavigableSet<K> navigableKeySet;
 
     @Override
-    public NavigableSet<K> navigableKeySet() {
+    public NavigableSet<@KeyFor({"this"}) K> navigableKeySet() {
       NavigableSet<K> result = navigableKeySet;
       return (result == null) ? navigableKeySet = new NavigableKeySet<>(this) : result;
     }
 
     @Override
-    public NavigableSet<K> descendingKeySet() {
+    public NavigableSet<@KeyFor({"this"}) K> descendingKeySet() {
       return forward().navigableKeySet();
     }
 
diff --git a/guava/src/com/google/common/collect/MinMaxPriorityQueue.java b/guava/src/com/google/common/collect/MinMaxPriorityQueue.java
index 181b3fbb50b3..fe3412d552ee 100644
--- a/guava/src/com/google/common/collect/MinMaxPriorityQueue.java
+++ b/guava/src/com/google/common/collect/MinMaxPriorityQueue.java
@@ -44,6 +44,8 @@
 import java.util.Queue;
 import javax.annotation.CheckForNull;
 import org.checkerframework.checker.nullness.qual.Nullable;
+import org.checkerframework.checker.nullness.qual.PolyNull;
+import org.checkerframework.checker.signedness.qual.PolySigned;
 
 /**
  * A double-ended priority queue, which provides constant-time access to both its least element and
@@ -911,7 +913,7 @@ public void clear() {
   }
 
   @Override
-  public Object[] toArray() {
+  public @PolyNull @PolySigned Object[] toArray(MinMaxPriorityQueue<@PolyNull @PolySigned E> this) {
     Object[] copyTo = new Object[size];
     System.arraycopy(queue, 0, copyTo, 0, size);
     return copyTo;
diff --git a/guava/src/com/google/common/collect/Multimap.java b/guava/src/com/google/common/collect/Multimap.java
index cb30feb1e05b..ca898c64d70d 100644
--- a/guava/src/com/google/common/collect/Multimap.java
+++ b/guava/src/com/google/common/collect/Multimap.java
@@ -30,6 +30,7 @@
 import java.util.function.BiConsumer;
 import javax.annotation.CheckForNull;
 import org.checkerframework.checker.nullness.qual.Nullable;
+import org.checkerframework.checker.signedness.qual.UnknownSignedness;
 import org.checkerframework.dataflow.qual.Pure;
 import org.checkerframework.framework.qual.AnnotatedFor;
 
@@ -189,14 +190,14 @@ public interface Multimap<K extends @Nullable Object, V extends @Nullable Object
    * key}.
    */
   @Pure
-  boolean containsKey(@CompatibleWith("K") @CheckForNull Object key);
+  boolean containsKey(@CompatibleWith("K") @CheckForNull @UnknownSignedness Object key);
 
   /**
    * Returns {@code true} if this multimap contains at least one key-value pair with the value
    * {@code value}.
    */
   @Pure
-  boolean containsValue(@CompatibleWith("V") @CheckForNull Object value);
+  boolean containsValue(@CompatibleWith("V") @CheckForNull @UnknownSignedness Object value);
 
   /**
    * Returns {@code true} if this multimap contains at least one key-value pair with the key {@code
diff --git a/guava/src/com/google/common/collect/Multimaps.java b/guava/src/com/google/common/collect/Multimaps.java
index 91d43b0db445..170acebc69eb 100644
--- a/guava/src/com/google/common/collect/Multimaps.java
+++ b/guava/src/com/google/common/collect/Multimaps.java
@@ -57,6 +57,8 @@
 import java.util.stream.Collector;
 import java.util.stream.Stream;
 import javax.annotation.CheckForNull;
+import org.checkerframework.checker.index.qual.NonNegative;
+import org.checkerframework.checker.nullness.qual.KeyFor;
 import org.checkerframework.checker.nullness.qual.Nullable;
 import org.checkerframework.checker.signedness.qual.UnknownSignedness;
 import org.checkerframework.dataflow.qual.Pure;
@@ -1140,13 +1142,13 @@ public int size() {
 
     @Pure
     @Override
-    public boolean containsKey(@CheckForNull Object key) {
+    public boolean containsKey(@CheckForNull @UnknownSignedness Object key) {
       return map.containsKey(key);
     }
 
     @Pure
     @Override
-    public boolean containsValue(@CheckForNull Object value) {
+    public boolean containsValue(@CheckForNull @UnknownSignedness Object value) {
       return map.containsValue(value);
     }
 
@@ -1539,7 +1541,7 @@ public void clear() {
     }
 
     @Override
-    public boolean containsKey(@CheckForNull Object key) {
+    public boolean containsKey(@CheckForNull @UnknownSignedness Object key) {
       return fromMultimap.containsKey(key);
     }
 
@@ -1799,7 +1801,7 @@ public Iterator<K> iterator() {
     }
 
     @Override
-    public int count(@CheckForNull Object element) {
+    public @NonNegative int count(@CheckForNull @UnknownSignedness Object element) {
       Collection<V> values = Maps.safeGet(multimap.asMap(), element);
       return (values == null) ? 0 : values.size();
     }
@@ -1948,7 +1950,7 @@ public Collection<V> remove(@CheckForNull @UnknownSignedness Object key) {
     }
 
     @Override
-    public Set<K> keySet() {
+    public Set<@KeyFor({"this"}) K> keySet() {
       return multimap.keySet();
     }
 
@@ -2259,7 +2261,7 @@ SetMultimap<K, V> filterFiltered(
     return new FilteredEntrySetMultimap<>(multimap.unfiltered(), predicate);
   }
 
-  static boolean equalsImpl(Multimap<?, ?> multimap, @CheckForNull Object object) {
+  static boolean equalsImpl(Multimap<?, ?> multimap, @CheckForNull @UnknownSignedness Object object) {
     if (object == multimap) {
       return true;
     }
diff --git a/guava/src/com/google/common/collect/Multisets.java b/guava/src/com/google/common/collect/Multisets.java
index 2fbcd54abafe..5a4fddfa5287 100644
--- a/guava/src/com/google/common/collect/Multisets.java
+++ b/guava/src/com/google/common/collect/Multisets.java
@@ -45,6 +45,7 @@
 import java.util.function.ToIntFunction;
 import java.util.stream.Collector;
 import javax.annotation.CheckForNull;
+import org.checkerframework.checker.index.qual.NonNegative;
 import org.checkerframework.checker.nullness.qual.Nullable;
 import org.checkerframework.checker.signedness.qual.UnknownSignedness;
 import org.checkerframework.dataflow.qual.Pure;
@@ -366,7 +367,7 @@ Iterator<Entry<E>> entryIterator() {
     }
 
     @Override
-    public int count(@CheckForNull Object element) {
+    public @NonNegative int count(@CheckForNull @UnknownSignedness Object element) {
       int count = unfiltered.count(element);
       if (count > 0) {
         @SuppressWarnings("unchecked") // element is equal to an E
@@ -436,7 +437,7 @@ public boolean isEmpty() {
       }
 
       @Override
-      public int count(@CheckForNull Object element) {
+      public @NonNegative int count(@CheckForNull @UnknownSignedness Object element) {
         return Math.max(multiset1.count(element), multiset2.count(element));
       }
 
@@ -498,7 +499,7 @@ protected Entry<E> computeNext() {
 
     return new ViewMultiset<E>() {
       @Override
-      public int count(@CheckForNull Object element) {
+      public @NonNegative int count(@CheckForNull @UnknownSignedness Object element) {
         int count1 = multiset1.count(element);
         return (count1 == 0) ? 0 : Math.min(count1, multiset2.count(element));
       }
@@ -572,7 +573,7 @@ public int size() {
       }
 
       @Override
-      public int count(@CheckForNull Object element) {
+      public @NonNegative int count(@CheckForNull @UnknownSignedness Object element) {
         return multiset1.count(element) + multiset2.count(element);
       }
 
@@ -635,7 +636,7 @@ protected Entry<E> computeNext() {
     // TODO(lowasser): consider making the entries live views
     return new ViewMultiset<E>() {
       @Override
-      public int count(@CheckForNull Object element) {
+      public @NonNegative int count(@CheckForNull @UnknownSignedness Object element) {
         int count1 = multiset1.count(element);
         return (count1 == 0) ? 0 : Math.max(0, count1 - multiset2.count(element));
       }
@@ -884,7 +885,7 @@ public String toString() {
   }
 
   /** An implementation of {@link Multiset#equals}. */
-  static boolean equalsImpl(Multiset<?> multiset, @CheckForNull Object object) {
+  static boolean equalsImpl(Multiset<?> multiset, @CheckForNull @UnknownSignedness Object object) {
     if (object == multiset) {
       return true;
     }
diff --git a/guava/src/com/google/common/collect/MutableClassToInstanceMap.java b/guava/src/com/google/common/collect/MutableClassToInstanceMap.java
index f0c54718382d..becc14055508 100644
--- a/guava/src/com/google/common/collect/MutableClassToInstanceMap.java
+++ b/guava/src/com/google/common/collect/MutableClassToInstanceMap.java
@@ -29,8 +29,13 @@
 import java.util.Set;
 import java.util.Spliterator;
 import javax.annotation.CheckForNull;
+import org.checkerframework.checker.nullness.qual.KeyFor;
 import org.checkerframework.checker.nullness.qual.Nullable;
+import org.checkerframework.checker.nullness.qual.PolyNull;
+import org.checkerframework.checker.signedness.qual.PolySigned;
+import org.checkerframework.checker.signedness.qual.UnknownSignedness;
 import org.checkerframework.framework.qual.AnnotatedFor;
+import org.checkerframework.framework.qual.CFComment;
 
 /**
  * A mutable class-to-instance map backed by an arbitrary user-provided map. See also {@link
@@ -100,7 +105,7 @@ public B setValue(B value) {
   }
 
   @Override
-  public Set<Entry<Class<? extends B>, B>> entrySet() {
+  public Set<Entry<@KeyFor({"this"}) Class<? extends B>, B>> entrySet() {
     return new ForwardingSet<Entry<Class<? extends B>, B>>() {
 
       @Override
@@ -125,8 +130,9 @@ Entry<Class<? extends B>, B> transform(Entry<Class<? extends B>, B> from) {
         };
       }
 
+      @CFComment("cannot write type qualifiers on receiver that is an anonymous class")
       @Override
-      public Object[] toArray() {
+      public @PolyNull @PolySigned Object[] toArray() {
         /*
          * standardToArray returns `@Nullable Object[]` rather than `Object[]` but only because it
          * can be used with collections that may contain null. This collection is a collection of
@@ -140,7 +146,7 @@ public Object[] toArray() {
 
       @Override
       @SuppressWarnings("nullness") // b/192354773 in our checker affects toArray declarations
-      public <T extends @Nullable Object> T[] toArray(T[] array) {
+      public <T extends @Nullable @UnknownSignedness Object> T[] toArray(T[] array) {
         return standardToArray(array);
       }
     };
diff --git a/guava/src/com/google/common/collect/ObjectArrays.java b/guava/src/com/google/common/collect/ObjectArrays.java
index f229ee379b0a..bf5b40fcb717 100644
--- a/guava/src/com/google/common/collect/ObjectArrays.java
+++ b/guava/src/com/google/common/collect/ObjectArrays.java
@@ -25,6 +25,7 @@
 import java.util.Arrays;
 import java.util.Collection;
 import org.checkerframework.checker.nullness.qual.Nullable;
+import org.checkerframework.checker.signedness.qual.PolySigned;
 import org.checkerframework.framework.qual.AnnotatedFor;
 
 /**
@@ -211,12 +212,12 @@ static void swap(Object[] array, int i, int j) {
   }
 
   @CanIgnoreReturnValue
-  static Object[] checkElementsNotNull(Object... array) {
+  static @PolySigned Object[] checkElementsNotNull(@PolySigned Object... array) {
     return checkElementsNotNull(array, array.length);
   }
 
   @CanIgnoreReturnValue
-  static Object[] checkElementsNotNull(Object[] array, int length) {
+  static @PolySigned Object[] checkElementsNotNull(@PolySigned Object[] array, int length) {
     for (int i = 0; i < length; i++) {
       checkElementNotNull(array[i], i);
     }
@@ -226,7 +227,7 @@ static Object[] checkElementsNotNull(Object[] array, int length) {
   // We do this instead of Preconditions.checkNotNull to save boxing and array
   // creation cost.
   @CanIgnoreReturnValue
-  static Object checkElementNotNull(Object element, int index) {
+  static @PolySigned Object checkElementNotNull(@PolySigned Object element, int index) {
     if (element == null) {
       throw new NullPointerException("at index " + index);
     }
diff --git a/guava/src/com/google/common/collect/RegularImmutableMap.java b/guava/src/com/google/common/collect/RegularImmutableMap.java
index 22e92b314f1f..a55923f518d6 100644
--- a/guava/src/com/google/common/collect/RegularImmutableMap.java
+++ b/guava/src/com/google/common/collect/RegularImmutableMap.java
@@ -32,6 +32,7 @@
 import java.util.IdentityHashMap;
 import java.util.function.BiConsumer;
 import javax.annotation.CheckForNull;
+import org.checkerframework.checker.nullness.qual.KeyFor;
 import org.checkerframework.checker.nullness.qual.Nullable;
 import org.checkerframework.checker.signedness.qual.UnknownSignedness;
 import org.checkerframework.dataflow.qual.Pure;
@@ -424,13 +425,13 @@ public boolean containsValue(@Nullable @UnknownSignedness Object arg0) {
 
   @SideEffectFree
   @Override
-  public ImmutableSet<Map.Entry<K, V>> entrySet() {
+  public ImmutableSet<Map.Entry<@KeyFor({"this"}) K, V>> entrySet() {
     return super.entrySet();
   }
 
   @SideEffectFree
   @Override
-  public ImmutableSet<K> keySet() {
+  public ImmutableSet<@KeyFor({"this"}) K> keySet() {
     return super.keySet();
   }
 
diff --git a/guava/src/com/google/common/collect/RegularImmutableMultiset.java b/guava/src/com/google/common/collect/RegularImmutableMultiset.java
index 026919e0d5cf..4e0cecdc13fd 100644
--- a/guava/src/com/google/common/collect/RegularImmutableMultiset.java
+++ b/guava/src/com/google/common/collect/RegularImmutableMultiset.java
@@ -25,7 +25,9 @@
 import java.util.Arrays;
 import java.util.Collection;
 import javax.annotation.CheckForNull;
+import org.checkerframework.checker.index.qual.NonNegative;
 import org.checkerframework.checker.nullness.qual.Nullable;
+import org.checkerframework.checker.signedness.qual.UnknownSignedness;
 
 /**
  * Implementation of {@link ImmutableMultiset} with zero or more elements.
@@ -157,7 +159,7 @@ boolean isPartialView() {
   }
 
   @Override
-  public int count(@CheckForNull Object element) {
+  public @NonNegative int count(@CheckForNull @UnknownSignedness Object element) {
     @Nullable ImmutableEntry<?>[] hashTable = this.hashTable;
     if (element == null || hashTable.length == 0) {
       return 0;
diff --git a/guava/src/com/google/common/collect/RegularImmutableSortedMultiset.java b/guava/src/com/google/common/collect/RegularImmutableSortedMultiset.java
index 4b7ba87427ac..94499933cb39 100644
--- a/guava/src/com/google/common/collect/RegularImmutableSortedMultiset.java
+++ b/guava/src/com/google/common/collect/RegularImmutableSortedMultiset.java
@@ -24,6 +24,8 @@
 import java.util.Comparator;
 import java.util.function.ObjIntConsumer;
 import javax.annotation.CheckForNull;
+import org.checkerframework.checker.index.qual.NonNegative;
+import org.checkerframework.checker.signedness.qual.UnknownSignedness;
 
 /**
  * An immutable sorted multiset with one or more distinct elements.
@@ -89,7 +91,7 @@ public Entry<E> lastEntry() {
   }
 
   @Override
-  public int count(@CheckForNull Object element) {
+  public @NonNegative int count(@CheckForNull @UnknownSignedness Object element) {
     int index = elementSet.indexOf(element);
     return (index >= 0) ? getCount(index) : 0;
   }
diff --git a/guava/src/com/google/common/collect/Sets.java b/guava/src/com/google/common/collect/Sets.java
index c99290590c14..bb4bea7a1ed8 100644
--- a/guava/src/com/google/common/collect/Sets.java
+++ b/guava/src/com/google/common/collect/Sets.java
@@ -1770,7 +1770,7 @@ static int hashCodeImpl(Set<?> s) {
   }
 
   /** An implementation for {@link Set#equals(Object)}. */
-  static boolean equalsImpl(Set<?> s, @CheckForNull Object object) {
+  static boolean equalsImpl(Set<?> s, @CheckForNull @UnknownSignedness Object object) {
     if (s == object) {
       return true;
     }
diff --git a/guava/src/com/google/common/collect/SingletonImmutableBiMap.java b/guava/src/com/google/common/collect/SingletonImmutableBiMap.java
index c5fb2b29892a..1e76ef710735 100644
--- a/guava/src/com/google/common/collect/SingletonImmutableBiMap.java
+++ b/guava/src/com/google/common/collect/SingletonImmutableBiMap.java
@@ -24,6 +24,7 @@
 import com.google.j2objc.annotations.RetainedWith;
 import java.util.function.BiConsumer;
 import javax.annotation.CheckForNull;
+import org.checkerframework.checker.signedness.qual.UnknownSignedness;
 
 /**
  * Implementation of {@link ImmutableMap} with exactly one entry.
@@ -54,7 +55,7 @@ private SingletonImmutableBiMap(K singleKey, V singleValue, ImmutableBiMap<V, K>
 
   @Override
   @CheckForNull
-  public V get(@CheckForNull Object key) {
+  public V get(@CheckForNull @UnknownSignedness Object key) {
     return singleKey.equals(key) ? singleValue : null;
   }
 
@@ -69,12 +70,12 @@ public void forEach(BiConsumer<? super K, ? super V> action) {
   }
 
   @Override
-  public boolean containsKey(@CheckForNull Object key) {
+  public boolean containsKey(@CheckForNull @UnknownSignedness Object key) {
     return singleKey.equals(key);
   }
 
   @Override
-  public boolean containsValue(@CheckForNull Object value) {
+  public boolean containsValue(@CheckForNull @UnknownSignedness Object value) {
     return singleValue.equals(value);
   }
 
diff --git a/guava/src/com/google/common/collect/StandardRowSortedTable.java b/guava/src/com/google/common/collect/StandardRowSortedTable.java
index bea5b7bb3a86..91c223d363b8 100644
--- a/guava/src/com/google/common/collect/StandardRowSortedTable.java
+++ b/guava/src/com/google/common/collect/StandardRowSortedTable.java
@@ -27,6 +27,7 @@
 import java.util.SortedMap;
 import java.util.SortedSet;
 import javax.annotation.CheckForNull;
+import org.checkerframework.checker.nullness.qual.KeyFor;
 
 /**
  * Implementation of {@code Table} whose iteration ordering across row keys is sorted by their
@@ -94,7 +95,7 @@ SortedMap<R, Map<C, V>> createRowMap() {
   @WeakOuter
   private class RowSortedMap extends RowMap implements SortedMap<R, Map<C, V>> {
     @Override
-    public SortedSet<R> keySet() {
+    public SortedSet<@KeyFor({"this"}) R> keySet() {
       return (SortedSet<R>) super.keySet();
     }
 
@@ -110,12 +111,12 @@ public Comparator<? super R> comparator() {
     }
 
     @Override
-    public R firstKey() {
+    public @KeyFor("this") R firstKey() {
       return sortedBackingMap().firstKey();
     }
 
     @Override
-    public R lastKey() {
+    public @KeyFor("this") R lastKey() {
       return sortedBackingMap().lastKey();
     }
 
diff --git a/guava/src/com/google/common/collect/StandardTable.java b/guava/src/com/google/common/collect/StandardTable.java
index 06defb0eb847..eafda57f98bd 100644
--- a/guava/src/com/google/common/collect/StandardTable.java
+++ b/guava/src/com/google/common/collect/StandardTable.java
@@ -45,6 +45,8 @@
 import java.util.Spliterator;
 import java.util.Spliterators;
 import javax.annotation.CheckForNull;
+import org.checkerframework.checker.nullness.qual.KeyFor;
+import org.checkerframework.checker.signedness.qual.UnknownSignedness;
 
 /**
  * {@link Table} implementation backed by a map that associates row keys with column key / value
@@ -102,7 +104,7 @@ public boolean containsRow(@CheckForNull Object rowKey) {
   }
 
   @Override
-  public boolean containsValue(@CheckForNull Object value) {
+  public boolean containsValue(@CheckForNull @UnknownSignedness Object value) {
     return value != null && super.containsValue(value);
   }
 
@@ -343,14 +345,14 @@ void maintainEmptyInvariant() {
     }
 
     @Override
-    public boolean containsKey(@CheckForNull Object key) {
+    public boolean containsKey(@CheckForNull @UnknownSignedness Object key) {
       updateBackingRowMapField();
       return (key != null && backingRowMap != null) && Maps.safeContainsKey(backingRowMap, key);
     }
 
     @Override
     @CheckForNull
-    public V get(@CheckForNull Object key) {
+    public V get(@CheckForNull @UnknownSignedness Object key) {
       updateBackingRowMapField();
       return (key != null && backingRowMap != null) ? Maps.safeGet(backingRowMap, key) : null;
     }
@@ -368,7 +370,7 @@ public V put(C key, V value) {
 
     @Override
     @CheckForNull
-    public V remove(@CheckForNull Object key) {
+    public V remove(@CheckForNull @UnknownSignedness Object key) {
       updateBackingRowMapField();
       if (backingRowMap == null) {
         return null;
@@ -474,18 +476,18 @@ public V put(R key, V value) {
 
     @Override
     @CheckForNull
-    public V get(@CheckForNull Object key) {
+    public V get(@CheckForNull @UnknownSignedness Object key) {
       return StandardTable.this.get(key, columnKey);
     }
 
     @Override
-    public boolean containsKey(@CheckForNull Object key) {
+    public boolean containsKey(@CheckForNull @UnknownSignedness Object key) {
       return StandardTable.this.contains(key, columnKey);
     }
 
     @Override
     @CheckForNull
-    public V remove(@CheckForNull Object key) {
+    public V remove(@CheckForNull @UnknownSignedness Object key) {
       return StandardTable.this.remove(key, columnKey);
     }
 
@@ -543,7 +545,7 @@ public void clear() {
       }
 
       @Override
-      public boolean contains(@CheckForNull Object o) {
+      public boolean contains(@CheckForNull @UnknownSignedness Object o) {
         if (o instanceof Entry) {
           Entry<?, ?> entry = (Entry<?, ?>) o;
           return containsMapping(entry.getKey(), columnKey, entry.getValue());
@@ -552,7 +554,7 @@ public boolean contains(@CheckForNull Object o) {
       }
 
       @Override
-      public boolean remove(@CheckForNull Object obj) {
+      public boolean remove(@CheckForNull @UnknownSignedness Object obj) {
         if (obj instanceof Entry) {
           Entry<?, ?> entry = (Entry<?, ?>) obj;
           return removeMapping(entry.getKey(), columnKey, entry.getValue());
@@ -626,12 +628,12 @@ private class KeySet extends Maps.KeySet<R, V> {
       }
 
       @Override
-      public boolean contains(@CheckForNull Object obj) {
+      public boolean contains(@CheckForNull @UnknownSignedness Object obj) {
         return StandardTable.this.contains(obj, columnKey);
       }
 
       @Override
-      public boolean remove(@CheckForNull Object obj) {
+      public boolean remove(@CheckForNull @UnknownSignedness Object obj) {
         return StandardTable.this.remove(obj, columnKey) != null;
       }
 
@@ -653,7 +655,7 @@ private class Values extends Maps.Values<R, V> {
       }
 
       @Override
-      public boolean remove(@CheckForNull Object obj) {
+      public boolean remove(@CheckForNull @UnknownSignedness Object obj) {
         return obj != null && removeFromColumnIf(Maps.<V>valuePredicateOnEntries(equalTo(obj)));
       }
 
@@ -703,7 +705,7 @@ public int size() {
     }
 
     @Override
-    public boolean remove(@CheckForNull Object obj) {
+    public boolean remove(@CheckForNull @UnknownSignedness Object obj) {
       if (obj == null) {
         return false;
       }
@@ -758,7 +760,7 @@ public boolean retainAll(Collection<?> c) {
     }
 
     @Override
-    public boolean contains(@CheckForNull Object obj) {
+    public boolean contains(@CheckForNull @UnknownSignedness Object obj) {
       return containsColumn(obj);
     }
   }
@@ -820,7 +822,7 @@ Map<R, Map<C, V>> createRowMap() {
   @WeakOuter
   class RowMap extends ViewCachingAbstractMap<R, Map<C, V>> {
     @Override
-    public boolean containsKey(@CheckForNull Object key) {
+    public boolean containsKey(@CheckForNull @UnknownSignedness Object key) {
       return containsRow(key);
     }
 
@@ -828,14 +830,14 @@ public boolean containsKey(@CheckForNull Object key) {
     @SuppressWarnings("unchecked")
     @Override
     @CheckForNull
-    public Map<C, V> get(@CheckForNull Object key) {
+    public Map<C, V> get(@CheckForNull @UnknownSignedness Object key) {
       // requireNonNull is safe because of the containsRow check.
       return containsRow(key) ? row((R) requireNonNull(key)) : null;
     }
 
     @Override
     @CheckForNull
-    public Map<C, V> remove(@CheckForNull Object key) {
+    public Map<C, V> remove(@CheckForNull @UnknownSignedness Object key) {
       return (key == null) ? null : backingMap.remove(key);
     }
 
@@ -864,7 +866,7 @@ public int size() {
       }
 
       @Override
-      public boolean contains(@CheckForNull Object obj) {
+      public boolean contains(@CheckForNull @UnknownSignedness Object obj) {
         if (obj instanceof Entry) {
           Entry<?, ?> entry = (Entry<?, ?>) obj;
           return entry.getKey() != null
@@ -875,7 +877,7 @@ public boolean contains(@CheckForNull Object obj) {
       }
 
       @Override
-      public boolean remove(@CheckForNull Object obj) {
+      public boolean remove(@CheckForNull @UnknownSignedness Object obj) {
         if (obj instanceof Entry) {
           Entry<?, ?> entry = (Entry<?, ?>) obj;
           return entry.getKey() != null
@@ -902,19 +904,19 @@ private class ColumnMap extends ViewCachingAbstractMap<C, Map<R, V>> {
     @SuppressWarnings("unchecked")
     @Override
     @CheckForNull
-    public Map<R, V> get(@CheckForNull Object key) {
+    public Map<R, V> get(@CheckForNull @UnknownSignedness Object key) {
       // requireNonNull is safe because of the containsColumn check.
       return containsColumn(key) ? column((C) requireNonNull(key)) : null;
     }
 
     @Override
-    public boolean containsKey(@CheckForNull Object key) {
+    public boolean containsKey(@CheckForNull @UnknownSignedness Object key) {
       return containsColumn(key);
     }
 
     @Override
     @CheckForNull
-    public Map<R, V> remove(@CheckForNull Object key) {
+    public Map<R, V> remove(@CheckForNull @UnknownSignedness Object key) {
       return containsColumn(key) ? removeColumn(key) : null;
     }
 
@@ -924,7 +926,7 @@ public Set<Entry<C, Map<R, V>>> createEntrySet() {
     }
 
     @Override
-    public Set<C> keySet() {
+    public Set<@KeyFor({"this"}) C> keySet() {
       return columnKeySet();
     }
 
@@ -953,7 +955,7 @@ public int size() {
       }
 
       @Override
-      public boolean contains(@CheckForNull Object obj) {
+      public boolean contains(@CheckForNull @UnknownSignedness Object obj) {
         if (obj instanceof Entry) {
           Entry<?, ?> entry = (Entry<?, ?>) obj;
           if (containsColumn(entry.getKey())) {
@@ -965,7 +967,7 @@ public boolean contains(@CheckForNull Object obj) {
       }
 
       @Override
-      public boolean remove(@CheckForNull Object obj) {
+      public boolean remove(@CheckForNull @UnknownSignedness Object obj) {
         /*
          * `o instanceof Entry` is guaranteed by `contains`, but we check it here to satisfy our
          * nullness checker.
@@ -1011,7 +1013,7 @@ private class ColumnMapValues extends Maps.Values<C, Map<R, V>> {
       }
 
       @Override
-      public boolean remove(@CheckForNull Object obj) {
+      public boolean remove(@CheckForNull @UnknownSignedness Object obj) {
         for (Entry<C, Map<R, V>> entry : ColumnMap.this.entrySet()) {
           if (entry.getValue().equals(obj)) {
             removeColumn(entry.getKey());
diff --git a/guava/src/com/google/common/collect/Synchronized.java b/guava/src/com/google/common/collect/Synchronized.java
index 29b201415ef8..ac28cb325f27 100644
--- a/guava/src/com/google/common/collect/Synchronized.java
+++ b/guava/src/com/google/common/collect/Synchronized.java
@@ -48,6 +48,7 @@
 import java.util.function.UnaryOperator;
 import java.util.stream.Stream;
 import javax.annotation.CheckForNull;
+import org.checkerframework.checker.index.qual.NonNegative;
 import org.checkerframework.checker.nullness.qual.KeyFor;
 import org.checkerframework.checker.nullness.qual.Nullable;
 import org.checkerframework.checker.nullness.qual.PolyNull;
@@ -536,7 +537,7 @@ Multiset<E> delegate() {
     }
 
     @Override
-    public int count(@CheckForNull Object o) {
+    public @NonNegative int count(@CheckForNull @UnknownSignedness Object o) {
       synchronized (mutex) {
         return delegate().count(o);
       }
@@ -666,7 +667,7 @@ public boolean containsKey(@CheckForNull Object key) {
 
     @Pure
     @Override
-    public boolean containsValue(@CheckForNull Object value) {
+    public boolean containsValue(@CheckForNull @UnknownSignedness Object value) {
       synchronized (mutex) {
         return delegate().containsValue(value);
       }
@@ -1043,7 +1044,7 @@ public Collection<V> getValue() {
 
     @Override
     //@SuppressWarnings("nullness") // b/192354773 in our checker affects toArray declarations
-    public <T extends @Nullable @UnknownSignedness Object> T[] toArray(T[] array) {
+    public <T extends @Nullable @UnknownSignedness Object> T[] toArray(@PolyNull T[] array) {
       synchronized (mutex) {
         return ObjectArrays.toArrayImpl(delegate(), array);
       }
@@ -1189,7 +1190,7 @@ public boolean isEmpty() {
 
     @SideEffectFree
     @Override
-    public Set<K> keySet() {
+    public Set<@KeyFor({"this"}) K> keySet() {
       synchronized (mutex) {
         if (keySet == null) {
           keySet = set(delegate().keySet(), mutex);
@@ -1230,31 +1231,31 @@ public V replace(K key, V value) {
     }
 
     @Override
-    public V computeIfAbsent(K key, Function<? super K, ? extends V> mappingFunction) {
+    public @PolyNull V computeIfAbsent(K key, Function<? super K, ? extends @PolyNull V> mappingFunction) {
       synchronized (mutex) {
         return delegate().computeIfAbsent(key, mappingFunction);
       }
     }
 
     @Override
-    public V computeIfPresent(
-        K key, BiFunction<? super K, ? super V, ? extends V> remappingFunction) {
+    public @PolyNull V computeIfPresent(
+        K key, BiFunction<? super K, ? super V, ? extends @PolyNull V> remappingFunction) {
       synchronized (mutex) {
         return delegate().computeIfPresent(key, remappingFunction);
       }
     }
 
     @Override
-    public V compute(
-        K key, BiFunction<? super K, ? super @Nullable V, ? extends V> remappingFunction) {
+    public @PolyNull V compute(
+        K key, BiFunction<? super K, ? super @Nullable V, ? extends @PolyNull V> remappingFunction) {
       synchronized (mutex) {
         return delegate().compute(key, remappingFunction);
       }
     }
 
     @Override
-    public V merge(
-        K key, V value, BiFunction<? super V, ? super V, ? extends V> remappingFunction) {
+    public @PolyNull V merge(
+        K key, V value, BiFunction<? super V, ? super V, ? extends @PolyNull V> remappingFunction) {
       synchronized (mutex) {
         return delegate().merge(key, value, remappingFunction);
       }
@@ -1356,7 +1357,7 @@ public Comparator<? super K> comparator() {
     }
 
     @Override
-    public K firstKey() {
+    public @KeyFor("this") K firstKey() {
       synchronized (mutex) {
         return delegate().firstKey();
       }
@@ -1370,7 +1371,7 @@ public SortedMap<K, V> headMap(K toKey) {
     }
 
     @Override
-    public K lastKey() {
+    public @KeyFor("this") K lastKey() {
       synchronized (mutex) {
         return delegate().lastKey();
       }
@@ -1470,7 +1471,7 @@ public Collection<V> get(@CheckForNull @UnknownSignedness Object key) {
 
     @SideEffectFree
     @Override
-    public Set<Map.Entry<K, Collection<V>>> entrySet() {
+    public Set<Map.Entry<@KeyFor({"this"}) K, Collection<V>>> entrySet() {
       synchronized (mutex) {
         if (asMapEntrySet == null) {
           asMapEntrySet = new SynchronizedAsMapEntries<>(delegate().entrySet(), mutex);
@@ -1523,7 +1524,7 @@ Collection<V> transform(Collection<V> from) {
   //Suppressed due to annotations on toArray
   @SuppressWarnings("nullness")
   @Override
-  public @Nullable @PolySigned Object[] toArray() { return super.toArray(); }
+  public @PolyNull @PolySigned Object[] toArray(SynchronizedAsMapValues<@PolyNull @PolySigned V> this) { return super.toArray(); }
 
   @SuppressWarnings("nullness")
   @Override public <T> T[] toArray(T[] arg0) { return super.toArray(arg0); }
@@ -1726,7 +1727,7 @@ public K ceilingKey(K key) {
     @CheckForNull transient NavigableSet<K> descendingKeySet;
 
     @Override
-    public NavigableSet<K> descendingKeySet() {
+    public NavigableSet<@KeyFor({"this"}) K> descendingKeySet() {
       synchronized (mutex) {
         if (descendingKeySet == null) {
           return descendingKeySet = Synchronized.navigableSet(delegate().descendingKeySet(), mutex);
@@ -1824,14 +1825,14 @@ public K lowerKey(K key) {
     }
 
     @Override
-    public Set<K> keySet() {
+    public Set<@KeyFor({"this"}) K> keySet() {
       return navigableKeySet();
     }
 
     @CheckForNull transient NavigableSet<K> navigableKeySet;
 
     @Override
-    public NavigableSet<K> navigableKeySet() {
+    public NavigableSet<@KeyFor({"this"}) K> navigableKeySet() {
       synchronized (mutex) {
         if (navigableKeySet == null) {
           return navigableKeySet = Synchronized.navigableSet(delegate().navigableKeySet(), mutex);
@@ -2186,7 +2187,7 @@ public boolean containsColumn(@CheckForNull Object columnKey) {
     }
 
     @Override
-    public boolean containsValue(@CheckForNull Object value) {
+    public boolean containsValue(@CheckForNull @UnknownSignedness Object value) {
       synchronized (mutex) {
         return delegate().containsValue(value);
       }
diff --git a/guava/src/com/google/common/collect/Table.java b/guava/src/com/google/common/collect/Table.java
index 3c9e7ec7a471..7821450634f7 100644
--- a/guava/src/com/google/common/collect/Table.java
+++ b/guava/src/com/google/common/collect/Table.java
@@ -26,6 +26,7 @@
 import java.util.Set;
 import javax.annotation.CheckForNull;
 import org.checkerframework.checker.nullness.qual.Nullable;
+import org.checkerframework.checker.signedness.qual.UnknownSignedness;
 
 /**
  * A collection that associates an ordered pair of keys, called a row key and a column key, with a
@@ -92,7 +93,7 @@ boolean contains(
    *
    * @param value value to search for
    */
-  boolean containsValue(@CompatibleWith("V") @CheckForNull Object value);
+  boolean containsValue(@CompatibleWith("V") @CheckForNull @UnknownSignedness Object value);
 
   /**
    * Returns the value corresponding to the given row and column keys, or {@code null} if no such
diff --git a/guava/src/com/google/common/collect/Tables.java b/guava/src/com/google/common/collect/Tables.java
index 9c58611d41b5..151d4693213e 100644
--- a/guava/src/com/google/common/collect/Tables.java
+++ b/guava/src/com/google/common/collect/Tables.java
@@ -39,6 +39,7 @@
 import java.util.stream.Collector;
 import javax.annotation.CheckForNull;
 import org.checkerframework.checker.nullness.qual.Nullable;
+import org.checkerframework.checker.signedness.qual.UnknownSignedness;
 
 /**
  * Provides static methods that involve a {@code Table}.
@@ -261,7 +262,7 @@ public boolean containsRow(@CheckForNull Object rowKey) {
     }
 
     @Override
-    public boolean containsValue(@CheckForNull Object value) {
+    public boolean containsValue(@CheckForNull @UnknownSignedness Object value) {
       return original.containsValue(value);
     }
 
@@ -751,7 +752,7 @@ Table<R, C, V> synchronizedTable(Table<R, C, V> table) {
     return Synchronized.table(table, null);
   }
 
-  static boolean equalsImpl(Table<?, ?, ?> table, @CheckForNull Object obj) {
+  static boolean equalsImpl(Table<?, ?, ?> table, @CheckForNull @UnknownSignedness Object obj) {
     if (obj == table) {
       return true;
     } else if (obj instanceof Table) {
diff --git a/guava/src/com/google/common/collect/TreeBasedTable.java b/guava/src/com/google/common/collect/TreeBasedTable.java
index 9ef210a54a62..96c2802e46bd 100644
--- a/guava/src/com/google/common/collect/TreeBasedTable.java
+++ b/guava/src/com/google/common/collect/TreeBasedTable.java
@@ -32,6 +32,7 @@
 import java.util.SortedSet;
 import java.util.TreeMap;
 import javax.annotation.CheckForNull;
+import org.checkerframework.checker.nullness.qual.KeyFor;
 
 /**
  * Implementation of {@code Table} whose row keys and column keys are ordered by their natural
@@ -190,7 +191,7 @@ private class TreeRow extends Row implements SortedMap<C, V> {
     }
 
     @Override
-    public SortedSet<C> keySet() {
+    public SortedSet<@KeyFor({"this"}) C> keySet() {
       return new Maps.SortedKeySet<>(this);
     }
 
@@ -231,7 +232,7 @@ public SortedMap<C, V> tailMap(C fromKey) {
     }
 
     @Override
-    public C firstKey() {
+    public @KeyFor("this") C firstKey() {
       updateBackingRowMapField();
       if (backingRowMap == null) {
         throw new NoSuchElementException();
@@ -240,7 +241,7 @@ public C firstKey() {
     }
 
     @Override
-    public C lastKey() {
+    public @KeyFor("this") C lastKey() {
       updateBackingRowMapField();
       if (backingRowMap == null) {
         throw new NoSuchElementException();
diff --git a/guava/src/com/google/common/collect/TreeMultimap.java b/guava/src/com/google/common/collect/TreeMultimap.java
index b8b9d5d26888..1451bfdac995 100644
--- a/guava/src/com/google/common/collect/TreeMultimap.java
+++ b/guava/src/com/google/common/collect/TreeMultimap.java
@@ -31,6 +31,7 @@
 import java.util.SortedSet;
 import java.util.TreeMap;
 import java.util.TreeSet;
+import org.checkerframework.checker.nullness.qual.KeyFor;
 import org.checkerframework.checker.nullness.qual.Nullable;
 import org.checkerframework.dataflow.qual.Pure;
 import org.checkerframework.dataflow.qual.SideEffectFree;
diff --git a/guava/src/com/google/common/collect/TreeMultiset.java b/guava/src/com/google/common/collect/TreeMultiset.java
index cd5e1d6c1921..62815d67da69 100644
--- a/guava/src/com/google/common/collect/TreeMultiset.java
+++ b/guava/src/com/google/common/collect/TreeMultiset.java
@@ -39,7 +39,9 @@
 import java.util.NoSuchElementException;
 import java.util.function.ObjIntConsumer;
 import javax.annotation.CheckForNull;
+import org.checkerframework.checker.index.qual.NonNegative;
 import org.checkerframework.checker.nullness.qual.Nullable;
+import org.checkerframework.checker.signedness.qual.UnknownSignedness;
 import org.checkerframework.dataflow.qual.Pure;
 import org.checkerframework.framework.qual.AnnotatedFor;
 
@@ -245,7 +247,7 @@ static int distinctElements(@CheckForNull AvlNode<?> node) {
   }
 
   @Override
-  public int count(@CheckForNull Object element) {
+  public @NonNegative int count(@CheckForNull @UnknownSignedness Object element) {
     try {
       @SuppressWarnings("unchecked")
       E e = (E) element;
diff --git a/guava/src/com/google/common/collect/TreeRangeMap.java b/guava/src/com/google/common/collect/TreeRangeMap.java
index 60e7bf3df874..01922c11bff0 100644
--- a/guava/src/com/google/common/collect/TreeRangeMap.java
+++ b/guava/src/com/google/common/collect/TreeRangeMap.java
@@ -40,7 +40,9 @@
 import java.util.Set;
 import java.util.function.BiFunction;
 import javax.annotation.CheckForNull;
+import org.checkerframework.checker.nullness.qual.KeyFor;
 import org.checkerframework.checker.nullness.qual.Nullable;
+import org.checkerframework.checker.signedness.qual.UnknownSignedness;
 
 /**
  * An implementation of {@code RangeMap} based on a {@code TreeMap}, supporting all optional
@@ -340,13 +342,13 @@ private final class AsMapOfRanges extends IteratorBasedAbstractMap<Range<K>, V>
     }
 
     @Override
-    public boolean containsKey(@CheckForNull Object key) {
+    public boolean containsKey(@CheckForNull @UnknownSignedness Object key) {
       return get(key) != null;
     }
 
     @Override
     @CheckForNull
-    public V get(@CheckForNull Object key) {
+    public V get(@CheckForNull @UnknownSignedness Object key) {
       if (key instanceof Range) {
         Range<?> range = (Range<?>) key;
         RangeMapEntry<K, V> rangeMapEntry = entriesByLowerBound.get(range.lowerBound);
@@ -642,13 +644,13 @@ public String toString() {
     class SubRangeMapAsMap extends AbstractMap<Range<K>, V> {
 
       @Override
-      public boolean containsKey(@CheckForNull Object key) {
+      public boolean containsKey(@CheckForNull @UnknownSignedness Object key) {
         return get(key) != null;
       }
 
       @Override
       @CheckForNull
-      public V get(@CheckForNull Object key) {
+      public V get(@CheckForNull @UnknownSignedness Object key) {
         try {
           if (key instanceof Range) {
             @SuppressWarnings("unchecked") // we catch ClassCastExceptions
@@ -682,7 +684,7 @@ public V get(@CheckForNull Object key) {
 
       @Override
       @CheckForNull
-      public V remove(@CheckForNull Object key) {
+      public V remove(@CheckForNull @UnknownSignedness Object key) {
         V value = get(key);
         if (value != null) {
           // it's definitely in the map, so the cast and requireNonNull are safe
@@ -716,7 +718,7 @@ private boolean removeEntryIf(Predicate<? super Entry<Range<K>, V>> predicate) {
       public Set<Range<K>> keySet() {
         return new Maps.KeySet<Range<K>, V>(SubRangeMapAsMap.this) {
           @Override
-          public boolean remove(@CheckForNull Object o) {
+          public boolean remove(@CheckForNull @UnknownSignedness Object o) {
             return SubRangeMapAsMap.this.remove(o) != null;
           }
 
diff --git a/guava/src/com/google/common/graph/MapIteratorCache.java b/guava/src/com/google/common/graph/MapIteratorCache.java
index a1c2a9d85ddf..d8ac2adc571b 100644
--- a/guava/src/com/google/common/graph/MapIteratorCache.java
+++ b/guava/src/com/google/common/graph/MapIteratorCache.java
@@ -102,7 +102,7 @@ final V getWithoutCaching(Object key) {
     return backingMap.get(key);
   }
 
-  final boolean containsKey(@CheckForNull Object key) {
+  final boolean containsKey(@CheckForNull @UnknownSignedness Object key) {
     return getIfCached(key) != null || backingMap.containsKey(key);
   }
 
diff --git a/guava/src/com/google/common/io/ByteArrayDataOutput.java b/guava/src/com/google/common/io/ByteArrayDataOutput.java
index 16660deae704..a42621905897 100644
--- a/guava/src/com/google/common/io/ByteArrayDataOutput.java
+++ b/guava/src/com/google/common/io/ByteArrayDataOutput.java
@@ -20,6 +20,7 @@
 import org.checkerframework.checker.index.qual.IndexOrHigh;
 import org.checkerframework.checker.index.qual.LTLengthOf;
 import org.checkerframework.checker.index.qual.NonNegative;
+import org.checkerframework.checker.signedness.qual.PolySigned;
 
 /**
  * An extension of {@code DataOutput} for writing to in-memory byte arrays; its methods offer
@@ -38,7 +39,7 @@ public interface ByteArrayDataOutput extends DataOutput {
   void write(byte b[]);
 
   @Override
-  void write(byte b[], @IndexOrHigh("#1") int off, @NonNegative @LTLengthOf(value = "#1", offset = "#2 - 1") int len);
+  void write(@PolySigned byte b[], @IndexOrHigh("#1") int off, @NonNegative @LTLengthOf(value = "#1", offset = "#2 - 1") int len);
 
   @Override
   void writeBoolean(boolean v);
diff --git a/guava/src/com/google/common/io/ByteStreams.java b/guava/src/com/google/common/io/ByteStreams.java
index 3a9b900f7f4b..febaebd1d036 100644
--- a/guava/src/com/google/common/io/ByteStreams.java
+++ b/guava/src/com/google/common/io/ByteStreams.java
@@ -551,7 +551,7 @@ public void write(byte[] b) {
     }
 
     @Override
-    public void write(byte[] b, @IndexOrHigh("#1") int off, @NonNegative @LTLengthOf(value = "#1", offset = "#2 - 1") int len) {
+    public void write(@PolySigned byte[] b, @IndexOrHigh("#1") int off, @NonNegative @LTLengthOf(value = "#1", offset = "#2 - 1") int len) {
       try {
         output.write(b, off, len);
       } catch (IOException impossible) {
diff --git a/guava/src/com/google/common/net/InetAddresses.java b/guava/src/com/google/common/net/InetAddresses.java
index 9881c803e1f3..8d7db9fe72ec 100644
--- a/guava/src/com/google/common/net/InetAddresses.java
+++ b/guava/src/com/google/common/net/InetAddresses.java
@@ -773,7 +773,6 @@ public static TeredoInfo getTeredoInfo(Inet6Address ip) {
    * @param ip {@link Inet6Address} to be examined for ISATAP address format
    * @return {@code true} if the argument is an ISATAP address
    */
-  @SuppressWarnings("value:cast.unsafe") // ip address should probably be unsigned bytes
   public static boolean isIsatapAddress(Inet6Address ip) {
 
     // If it's a Teredo address with the right port (41217, or 0xa101)
@@ -873,7 +872,6 @@ public static Inet4Address getEmbeddedIPv4ClientAddress(Inet6Address ip) {
    * @return {@code true} if the argument is a valid "mapped" address
    * @since 10.0
    */
-  @SuppressWarnings("value:cast.unsafe") // ip address should probably be unsigned bytes
   public static boolean isMappedIPv4Address(String ipString) {
     byte[] bytes = ipStringToBytes(ipString);
     if (bytes != null && bytes.length == 16) {
@@ -1096,7 +1094,6 @@ public static InetAddress fromLittleEndianByteArray(byte[] addr) throws UnknownH
    * @throws IllegalArgumentException if InetAddress is at the beginning of its range
    * @since 18.0
    */
-  @SuppressWarnings("value:cast.unsafe") // ip address should probably be unsigned bytes
   public static InetAddress decrement(InetAddress address) {
     byte[] addr = address.getAddress();
     int i = addr.length - 1;
@@ -1120,7 +1117,6 @@ public static InetAddress decrement(InetAddress address) {
    * @throws IllegalArgumentException if InetAddress is at the end of its range
    * @since 10.0
    */
-  @SuppressWarnings("value:cast.unsafe") // ip address should probably be unsigned bytes
   public static InetAddress increment(InetAddress address) {
     byte[] addr = address.getAddress();
     int i = addr.length - 1;
@@ -1143,7 +1139,6 @@ public static InetAddress increment(InetAddress address) {
    *     ffff:ffff:ffff:ffff:ffff:ffff:ffff:ffff for IPv6
    * @since 10.0
    */
-  @SuppressWarnings("value:cast.unsafe") // ip address should probably be unsigned bytes
   public static boolean isMaximum(InetAddress address) {
     byte[] addr = address.getAddress();
     for (byte b : addr) {
diff --git a/guava/src/com/google/common/primitives/UnsignedBytes.java b/guava/src/com/google/common/primitives/UnsignedBytes.java
index 4167cd664ce0..0db9995e4856 100644
--- a/guava/src/com/google/common/primitives/UnsignedBytes.java
+++ b/guava/src/com/google/common/primitives/UnsignedBytes.java
@@ -64,7 +64,6 @@ private UnsignedBytes() {}
    *
    * @since 10.0
    */
-  @SuppressWarnings("value:cast.unsafe") // https://github.com/kelloggm/checker-framework/issues/149
   public static final @Unsigned byte MAX_POWER_OF_TWO = (byte) 0x80;
 
   /**
@@ -72,7 +71,6 @@ private UnsignedBytes() {}
    *
    * @since 13.0
    */
-  @SuppressWarnings("value:cast.unsafe") // https://github.com/kelloggm/checker-framework/issues/149
   public static final @Unsigned byte MAX_VALUE = (byte) 0xFF;
 
   private static final int UNSIGNED_MASK = 0xFF;
diff --git a/guava/src/com/google/common/reflect/MutableTypeToInstanceMap.java b/guava/src/com/google/common/reflect/MutableTypeToInstanceMap.java
index fe6a25759aff..49fc55419f8d 100644
--- a/guava/src/com/google/common/reflect/MutableTypeToInstanceMap.java
+++ b/guava/src/com/google/common/reflect/MutableTypeToInstanceMap.java
@@ -27,6 +27,7 @@
 import java.util.Map;
 import java.util.Set;
 import javax.annotation.CheckForNull;
+import org.checkerframework.checker.nullness.qual.KeyFor;
 import org.checkerframework.checker.nullness.qual.Nullable;
 import org.checkerframework.checker.nullness.qual.PolyNull;
 import org.checkerframework.checker.signedness.qual.PolySigned;
@@ -102,7 +103,7 @@ public void putAll(Map<? extends TypeToken<? extends B>, ? extends B> map) {
   }
 
   @Override
-  public Set<Entry<TypeToken<? extends B>, B>> entrySet() {
+  public Set<Entry<@KeyFor({"this"}) TypeToken<? extends B>, B>> entrySet() {
     return UnmodifiableEntry.transformEntries(super.entrySet());
   }
 
diff --git a/guava/src/com/google/common/util/concurrent/AtomicLongMap.java b/guava/src/com/google/common/util/concurrent/AtomicLongMap.java
index 456b3aceb1ac..3774e744fca8 100644
--- a/guava/src/com/google/common/util/concurrent/AtomicLongMap.java
+++ b/guava/src/com/google/common/util/concurrent/AtomicLongMap.java
@@ -30,6 +30,7 @@
 import java.util.function.LongBinaryOperator;
 import java.util.function.LongUnaryOperator;
 import javax.annotation.CheckForNull;
+import org.checkerframework.checker.signedness.qual.UnknownSignedness;
 
 /**
  * A map containing {@code long} values that can be atomically updated. While writes to a
@@ -276,7 +277,7 @@ private Map<K, Long> createAsMap() {
   }
 
   /** Returns true if this map contains a mapping for the specified key. */
-  public boolean containsKey(Object key) {
+  public boolean containsKey(@UnknownSignedness Object key) {
     return map.containsKey(key);
   }
 
diff --git a/pom.xml b/pom.xml
index ab81fb618d0e..088202ecbc52 100644
--- a/pom.xml
+++ b/pom.xml
@@ -15,7 +15,7 @@
     <!-- Override this with -Dtest.include="**/SomeTest.java" on the CLI -->
     <test.include>%regex[.*.class]</test.include>
     <truth.version>1.1.2</truth.version>
-    <checker-framework.version>3.32.0</checker-framework.version>
+    <checker-framework.version>3.34.0</checker-framework.version>
     <animal.sniffer.version>1.20</animal.sniffer.version>
     <maven-javadoc-plugin.version>3.1.0</maven-javadoc-plugin.version>
     <!-- Empty for all JDKs but 9-12 -->

From b5332324b6d5f780520f40daba5294117252dee9 Mon Sep 17 00:00:00 2001
From: Mark Roberts <markro49@users.noreply.github.com>
Date: Sun, 4 Jun 2023 14:52:14 -0700
Subject: [PATCH 18/21] Add index annotations to fix cannot override warnings

---
 .../src/com/google/common/base/Splitter.java  | 16 ++++++-------
 .../com/google/common/cache/LocalCache.java   | 13 ++++++-----
 .../collect/AbstractIndexedListIterator.java  |  5 ++--
 .../collect/AbstractMapBasedMultimap.java     |  9 ++++----
 .../collect/AbstractMapBasedMultiset.java     |  2 +-
 .../common/collect/AbstractMultimap.java      |  3 ++-
 .../common/collect/AbstractMultiset.java      |  3 ++-
 .../google/common/collect/AbstractTable.java  |  5 ++--
 .../com/google/common/collect/ArrayTable.java |  3 ++-
 .../google/common/collect/CartesianList.java  |  5 ++--
 .../google/common/collect/Collections2.java   |  9 ++++----
 .../google/common/collect/CompactHashMap.java |  3 ++-
 .../google/common/collect/CompactHashSet.java |  3 ++-
 .../collect/ConcurrentHashMultiset.java       |  4 ++--
 .../common/collect/DenseImmutableTable.java   |  3 ++-
 .../DescendingImmutableSortedMultiset.java    |  2 +-
 .../collect/DescendingImmutableSortedSet.java |  3 ++-
 .../common/collect/DescendingMultiset.java    |  3 ++-
 .../common/collect/EmptyContiguousSet.java    |  3 ++-
 .../google/common/collect/EnumMultiset.java   |  2 +-
 .../common/collect/FilteredEntryMultimap.java |  5 ++--
 .../collect/FilteredMultimapValues.java       |  3 ++-
 .../google/common/collect/ForwardingMap.java  |  3 ++-
 .../com/google/common/collect/HashBiMap.java  |  5 ++--
 .../common/collect/ImmutableAsList.java       |  3 ++-
 .../common/collect/ImmutableEnumMap.java      |  3 ++-
 .../common/collect/ImmutableEnumSet.java      |  3 ++-
 .../google/common/collect/ImmutableList.java  |  5 ++--
 .../google/common/collect/ImmutableMap.java   |  3 ++-
 .../common/collect/ImmutableMapEntrySet.java  |  3 ++-
 .../common/collect/ImmutableMapKeySet.java    |  3 ++-
 .../common/collect/ImmutableMapValues.java    |  3 ++-
 .../common/collect/ImmutableMultimap.java     |  6 ++---
 .../common/collect/ImmutableMultiset.java     |  5 ++--
 .../common/collect/ImmutableRangeMap.java     |  3 ++-
 .../common/collect/ImmutableRangeSet.java     |  7 +++---
 .../common/collect/ImmutableSetMultimap.java  |  3 ++-
 .../common/collect/ImmutableSortedMap.java    |  3 ++-
 .../common/collect/IndexedImmutableSet.java   |  3 ++-
 .../collect/JdkBackedImmutableBiMap.java      |  5 ++--
 .../common/collect/JdkBackedImmutableMap.java |  3 ++-
 .../collect/JdkBackedImmutableMultiset.java   |  2 +-
 .../common/collect/JdkBackedImmutableSet.java |  3 ++-
 .../common/collect/LinkedHashMultimap.java    |  3 ++-
 .../common/collect/LinkedListMultimap.java    | 17 +++++++-------
 .../src/com/google/common/collect/Lists.java  | 23 ++++++++++---------
 .../common/collect/MapMakerInternalMap.java   |  9 ++++----
 guava/src/com/google/common/collect/Maps.java | 17 +++++++-------
 .../common/collect/MinMaxPriorityQueue.java   |  3 ++-
 .../com/google/common/collect/Multimaps.java  |  8 +++----
 .../com/google/common/collect/Multiset.java   |  3 ++-
 .../com/google/common/collect/Multisets.java  |  6 ++---
 .../common/collect/RegularContiguousSet.java  |  3 ++-
 .../common/collect/RegularImmutableBiMap.java |  5 ++--
 .../common/collect/RegularImmutableList.java  |  3 ++-
 .../common/collect/RegularImmutableMap.java   |  7 +++---
 .../collect/RegularImmutableMultiset.java     |  3 ++-
 .../common/collect/RegularImmutableSet.java   |  3 ++-
 .../RegularImmutableSortedMultiset.java       |  3 ++-
 .../collect/RegularImmutableSortedSet.java    |  3 ++-
 .../common/collect/RegularImmutableTable.java |  5 ++--
 guava/src/com/google/common/collect/Sets.java | 19 +++++++--------
 .../collect/SingletonImmutableBiMap.java      |  3 ++-
 .../collect/SingletonImmutableList.java       |  3 ++-
 .../common/collect/SingletonImmutableSet.java |  3 ++-
 .../google/common/collect/StandardTable.java  | 11 +++++----
 .../google/common/collect/Synchronized.java   |  4 ++--
 .../collect/TransformedListIterator.java      |  5 ++--
 .../google/common/collect/TreeMultiset.java   |  2 +-
 .../google/common/collect/TreeRangeMap.java   |  5 ++--
 .../google/common/collect/TreeRangeSet.java   |  7 +++---
 .../common/graph/AbstractBaseGraph.java       |  3 ++-
 .../AbstractDirectedNetworkConnections.java   |  3 ++-
 .../google/common/graph/AbstractNetwork.java  |  3 ++-
 .../graph/DirectedGraphConnections.java       |  7 +++---
 .../DirectedMultiNetworkConnections.java      |  3 ++-
 .../google/common/graph/EdgesConnecting.java  |  3 ++-
 .../google/common/graph/IncidentEdgeSet.java  |  3 ++-
 .../google/common/graph/MapIteratorCache.java |  3 ++-
 .../UndirectedMultiNetworkConnections.java    |  3 ++-
 .../AbstractNonStreamingHashFunction.java     |  2 +-
 .../google/common/hash/Fingerprint2011.java   |  3 ++-
 guava/src/com/google/common/hash/Funnels.java |  4 +++-
 .../common/hash/HashingOutputStream.java      |  5 ++--
 .../com/google/common/io/BaseEncoding.java    | 10 ++++----
 .../com/google/common/net/PercentEscaper.java |  4 +++-
 86 files changed, 252 insertions(+), 177 deletions(-)

diff --git a/guava/src/com/google/common/base/Splitter.java b/guava/src/com/google/common/base/Splitter.java
index 1a3cacca25e6..cc606763956c 100644
--- a/guava/src/com/google/common/base/Splitter.java
+++ b/guava/src/com/google/common/base/Splitter.java
@@ -154,12 +154,12 @@ public static Splitter on(final CharMatcher separatorMatcher) {
           public SplittingIterator iterator(Splitter splitter, final CharSequence toSplit) {
             return new SplittingIterator(splitter, toSplit) {
               @Override
-              @GTENegativeOne int separatorStart(@NonNegative int start) {
+              @GTENegativeOne @LTEqLengthOf("toSplit") int separatorStart(@NonNegative int start) {
                 return separatorMatcher.indexIn(toSplit, start);
               }
 
               @Override
-              @NonNegative int separatorEnd(@NonNegative int separatorPosition) {
+              @IndexOrHigh("toSplit") int separatorEnd(@NonNegative int separatorPosition) {
                 return separatorPosition + 1;
               }
             };
@@ -186,7 +186,7 @@ public static Splitter on(final @MinLen(1) String separator) {
           public SplittingIterator iterator(Splitter splitter, CharSequence toSplit) {
             return new SplittingIterator(splitter, toSplit) {
               @Override
-              public @GTENegativeOne int separatorStart(@NonNegative int start) {
+              public @GTENegativeOne @LTEqLengthOf("toSplit") int separatorStart(@NonNegative int start) {
                 int separatorLength = separator.length();
 
                 positions:
@@ -202,7 +202,7 @@ public SplittingIterator iterator(Splitter splitter, CharSequence toSplit) {
               }
 
               @Override
-              public @NonNegative int separatorEnd(@NonNegative int separatorPosition) {
+              public @IndexOrHigh("toSplit") int separatorEnd(@NonNegative int separatorPosition) {
                 return separatorPosition + separator.length();
               }
             };
@@ -238,12 +238,12 @@ public SplittingIterator iterator(final Splitter splitter, CharSequence toSplit)
             final CommonMatcher matcher = separatorPattern.matcher(toSplit);
             return new SplittingIterator(splitter, toSplit) {
               @Override
-              public @GTENegativeOne int separatorStart(@NonNegative int start) {
+              public @GTENegativeOne @LTEqLengthOf("toSplit") int separatorStart(@NonNegative int start) {
                 return matcher.find(start) ? matcher.start() : -1;
               }
 
               @Override
-              public @NonNegative int separatorEnd(@NonNegative int separatorPosition) {
+              public @IndexOrHigh("toSplit") int separatorEnd(@NonNegative int separatorPosition) {
                 return matcher.end();
               }
             };
@@ -295,13 +295,13 @@ public static Splitter fixedLength(final @Positive int length) {
           public SplittingIterator iterator(final Splitter splitter, CharSequence toSplit) {
             return new SplittingIterator(splitter, toSplit) {
               @Override
-              public @GTENegativeOne int separatorStart(@NonNegative int start) {
+              public @GTENegativeOne @LTEqLengthOf("toSplit") int separatorStart(@NonNegative int start) {
                 int nextChunkStart = start + length;
                 return (nextChunkStart < toSplit.length() ? nextChunkStart : -1);
               }
 
               @Override
-              public @NonNegative int separatorEnd(@NonNegative int separatorPosition) {
+              public @IndexOrHigh("toSplit") int separatorEnd(@NonNegative int separatorPosition) {
                 return separatorPosition;
               }
             };
diff --git a/guava/src/com/google/common/cache/LocalCache.java b/guava/src/com/google/common/cache/LocalCache.java
index 7dd0e9ccc509..3ab2652d63ec 100644
--- a/guava/src/com/google/common/cache/LocalCache.java
+++ b/guava/src/com/google/common/cache/LocalCache.java
@@ -85,6 +85,7 @@
 import java.util.function.Predicate;
 import java.util.logging.Level;
 import java.util.logging.Logger;
+import org.checkerframework.checker.index.qual.NonNegative;
 import org.checkerframework.checker.nullness.qual.KeyFor;
 import org.checkerframework.checker.nullness.qual.Nullable;
 import org.checkerframework.checker.nullness.qual.PolyNull;
@@ -919,7 +920,7 @@ public Object poll() {
         }
 
         @Override
-        public int size() {
+        public @NonNegative int size() {
           return 0;
         }
 
@@ -3728,7 +3729,7 @@ public boolean isEmpty() {
     }
 
     @Override
-    public int size() {
+    public @NonNegative int size() {
       int size = 0;
       for (ReferenceEntry<K, V> e = head.getNextInWriteQueue();
           e != head;
@@ -3867,7 +3868,7 @@ public boolean isEmpty() {
     }
 
     @Override
-    public int size() {
+    public @NonNegative int size() {
       int size = 0;
       for (ReferenceEntry<K, V> e = head.getNextInAccessQueue();
           e != head;
@@ -3952,7 +3953,7 @@ long longSize() {
   }
 
   @Override
-  public int size() {
+  public @NonNegative int size() {
     return Ints.saturatedCast(longSize());
   }
 
@@ -4514,7 +4515,7 @@ public Entry<K, V> next() {
 
   abstract class AbstractCacheSet<T> extends AbstractSet<T> {
     @Override
-    public int size() {
+    public @NonNegative int size() {
       return LocalCache.this.size();
     }
 
@@ -4586,7 +4587,7 @@ public boolean remove(@UnknownSignedness Object o) {
 
   final class Values extends AbstractCollection<V> {
     @Override
-    public int size() {
+    public @NonNegative int size() {
       return LocalCache.this.size();
     }
 
diff --git a/guava/src/com/google/common/collect/AbstractIndexedListIterator.java b/guava/src/com/google/common/collect/AbstractIndexedListIterator.java
index abb3960b261e..b4872137b70d 100644
--- a/guava/src/com/google/common/collect/AbstractIndexedListIterator.java
+++ b/guava/src/com/google/common/collect/AbstractIndexedListIterator.java
@@ -21,6 +21,7 @@
 import com.google.common.annotations.GwtCompatible;
 import java.util.ListIterator;
 import java.util.NoSuchElementException;
+import org.checkerframework.checker.index.qual.NonNegative;
 import org.checkerframework.checker.nullness.qual.Nullable;
 
 /**
@@ -83,7 +84,7 @@ public final E next() {
   }
 
   @Override
-  public final int nextIndex() {
+  public final @NonNegative int nextIndex() {
     return position;
   }
 
@@ -102,7 +103,7 @@ public final E previous() {
   }
 
   @Override
-  public final int previousIndex() {
+  public final @NonNegative int previousIndex() {
     return position - 1;
   }
 }
diff --git a/guava/src/com/google/common/collect/AbstractMapBasedMultimap.java b/guava/src/com/google/common/collect/AbstractMapBasedMultimap.java
index a9a4525f7b61..fca4a436dded 100644
--- a/guava/src/com/google/common/collect/AbstractMapBasedMultimap.java
+++ b/guava/src/com/google/common/collect/AbstractMapBasedMultimap.java
@@ -45,6 +45,7 @@
 import java.util.Spliterator;
 import java.util.function.BiConsumer;
 import javax.annotation.CheckForNull;
+import org.checkerframework.checker.index.qual.NonNegative;
 import org.checkerframework.checker.nullness.qual.KeyFor;
 import org.checkerframework.checker.nullness.qual.Nullable;
 import org.checkerframework.checker.signedness.qual.UnknownSignedness;
@@ -397,7 +398,7 @@ void addToMap() {
     }
 
     @Override
-    public int size() {
+    public @NonNegative int size() {
       refreshIfEmpty();
       return delegate.size();
     }
@@ -891,12 +892,12 @@ public V previous() {
       }
 
       @Override
-      public int nextIndex() {
+      public @NonNegative int nextIndex() {
         return getDelegateListIterator().nextIndex();
       }
 
       @Override
-      public int previousIndex() {
+      public @NonNegative int previousIndex() {
         return getDelegateListIterator().previousIndex();
       }
 
@@ -1381,7 +1382,7 @@ public Collection<V> get(@CheckForNull @UnknownSignedness Object key) {
     }
 
     @Override
-    public int size() {
+    public @NonNegative int size() {
       return submap.size();
     }
 
diff --git a/guava/src/com/google/common/collect/AbstractMapBasedMultiset.java b/guava/src/com/google/common/collect/AbstractMapBasedMultiset.java
index 629816124d93..10f52a9edafd 100644
--- a/guava/src/com/google/common/collect/AbstractMapBasedMultiset.java
+++ b/guava/src/com/google/common/collect/AbstractMapBasedMultiset.java
@@ -191,7 +191,7 @@ int distinctElements() {
 
   @Pure
   @Override
-  public int size() {
+  public @NonNegative int size() {
     return Ints.saturatedCast(size);
   }
 
diff --git a/guava/src/com/google/common/collect/AbstractMultimap.java b/guava/src/com/google/common/collect/AbstractMultimap.java
index 933a4a0bd374..6b09265972eb 100644
--- a/guava/src/com/google/common/collect/AbstractMultimap.java
+++ b/guava/src/com/google/common/collect/AbstractMultimap.java
@@ -31,6 +31,7 @@
 import java.util.Spliterator;
 import java.util.Spliterators;
 import javax.annotation.CheckForNull;
+import org.checkerframework.checker.index.qual.NonNegative;
 import org.checkerframework.checker.nullness.qual.Nullable;
 import org.checkerframework.checker.signedness.qual.UnknownSignedness;
 import org.checkerframework.dataflow.qual.Pure;
@@ -217,7 +218,7 @@ public Spliterator<V> spliterator() {
     }
 
     @Override
-    public int size() {
+    public @NonNegative int size() {
       return AbstractMultimap.this.size();
     }
 
diff --git a/guava/src/com/google/common/collect/AbstractMultiset.java b/guava/src/com/google/common/collect/AbstractMultiset.java
index ab0e5d5d13a9..d7f0015136a9 100644
--- a/guava/src/com/google/common/collect/AbstractMultiset.java
+++ b/guava/src/com/google/common/collect/AbstractMultiset.java
@@ -27,6 +27,7 @@
 import java.util.Iterator;
 import java.util.Set;
 import javax.annotation.CheckForNull;
+import org.checkerframework.checker.index.qual.NonNegative;
 import org.checkerframework.checker.nullness.qual.Nullable;
 import org.checkerframework.checker.signedness.qual.UnknownSignedness;
 import org.checkerframework.dataflow.qual.Pure;
@@ -194,7 +195,7 @@ public Iterator<Entry<E>> iterator() {
     }
 
     @Override
-    public int size() {
+    public @NonNegative int size() {
       return distinctElements();
     }
   }
diff --git a/guava/src/com/google/common/collect/AbstractTable.java b/guava/src/com/google/common/collect/AbstractTable.java
index 934a6adb6c3c..95cb55180f0c 100644
--- a/guava/src/com/google/common/collect/AbstractTable.java
+++ b/guava/src/com/google/common/collect/AbstractTable.java
@@ -26,6 +26,7 @@
 import java.util.Set;
 import java.util.Spliterator;
 import javax.annotation.CheckForNull;
+import org.checkerframework.checker.index.qual.NonNegative;
 import org.checkerframework.checker.nullness.qual.Nullable;
 import org.checkerframework.checker.signedness.qual.UnknownSignedness;
 
@@ -174,7 +175,7 @@ public Spliterator<Cell<R, C, V>> spliterator() {
     }
 
     @Override
-    public int size() {
+    public @NonNegative int size() {
       return AbstractTable.this.size();
     }
   }
@@ -228,7 +229,7 @@ public void clear() {
     }
 
     @Override
-    public int size() {
+    public @NonNegative int size() {
       return AbstractTable.this.size();
     }
   }
diff --git a/guava/src/com/google/common/collect/ArrayTable.java b/guava/src/com/google/common/collect/ArrayTable.java
index 34c7dc758f33..3c9411776d3d 100644
--- a/guava/src/com/google/common/collect/ArrayTable.java
+++ b/guava/src/com/google/common/collect/ArrayTable.java
@@ -38,6 +38,7 @@
 import java.util.Set;
 import java.util.Spliterator;
 import javax.annotation.CheckForNull;
+import org.checkerframework.checker.index.qual.NonNegative;
 import org.checkerframework.checker.nullness.qual.KeyFor;
 import org.checkerframework.checker.nullness.qual.Nullable;
 import org.checkerframework.checker.signedness.qual.UnknownSignedness;
@@ -216,7 +217,7 @@ K getKey(int index) {
     abstract V setValue(int index, @ParametricNullness V newValue);
 
     @Override
-    public int size() {
+    public @NonNegative int size() {
       return keyIndex.size();
     }
 
diff --git a/guava/src/com/google/common/collect/CartesianList.java b/guava/src/com/google/common/collect/CartesianList.java
index 4c31b12998e5..beaa71675113 100644
--- a/guava/src/com/google/common/collect/CartesianList.java
+++ b/guava/src/com/google/common/collect/CartesianList.java
@@ -23,6 +23,7 @@
 import java.util.ListIterator;
 import java.util.RandomAccess;
 import javax.annotation.CheckForNull;
+import org.checkerframework.checker.index.qual.NonNegative;
 
 /**
  * Implementation of {@link Lists#cartesianProduct(List)}.
@@ -117,7 +118,7 @@ public ImmutableList<E> get(int index) {
     return new ImmutableList<E>() {
 
       @Override
-      public int size() {
+      public @NonNegative int size() {
         return axes.size();
       }
 
@@ -136,7 +137,7 @@ boolean isPartialView() {
   }
 
   @Override
-  public int size() {
+  public @NonNegative int size() {
     return axesSizeProduct[0];
   }
 
diff --git a/guava/src/com/google/common/collect/Collections2.java b/guava/src/com/google/common/collect/Collections2.java
index 19c3955ec2fe..868b9f69ea5e 100644
--- a/guava/src/com/google/common/collect/Collections2.java
+++ b/guava/src/com/google/common/collect/Collections2.java
@@ -39,6 +39,7 @@
 import java.util.Spliterator;
 import java.util.function.Consumer;
 import javax.annotation.CheckForNull;
+import org.checkerframework.checker.index.qual.NonNegative;
 import org.checkerframework.checker.nullness.qual.Nullable;
 import org.checkerframework.checker.nullness.qual.PolyNull;
 import org.checkerframework.checker.signedness.qual.PolySigned;
@@ -230,7 +231,7 @@ public boolean removeIf(java.util.function.Predicate<? super E> filter) {
 
     @Pure
     @Override
-    public int size() {
+    public @NonNegative int size() {
       int size = 0;
       for (E e : unfiltered) {
         if (predicate.apply(e)) {
@@ -326,7 +327,7 @@ public boolean removeIf(java.util.function.Predicate<? super T> filter) {
     }
 
     @Override
-    public int size() {
+    public @NonNegative int size() {
       return fromCollection.size();
     }
   }
@@ -497,7 +498,7 @@ private static <E> int calculateSize(
     }
 
     @Override
-    public int size() {
+    public @NonNegative int size() {
       return size;
     }
 
@@ -624,7 +625,7 @@ private static final class PermutationCollection<E> extends AbstractCollection<L
     }
 
     @Override
-    public int size() {
+    public @NonNegative int size() {
       return IntMath.factorial(inputList.size());
     }
 
diff --git a/guava/src/com/google/common/collect/CompactHashMap.java b/guava/src/com/google/common/collect/CompactHashMap.java
index 73a33d09cea7..9c15a2aecd33 100644
--- a/guava/src/com/google/common/collect/CompactHashMap.java
+++ b/guava/src/com/google/common/collect/CompactHashMap.java
@@ -51,6 +51,7 @@
 import java.util.function.BiFunction;
 import java.util.function.Consumer;
 import javax.annotation.CheckForNull;
+import org.checkerframework.checker.index.qual.NonNegative;
 import org.checkerframework.checker.nullness.qual.KeyFor;
 import org.checkerframework.checker.nullness.qual.Nullable;
 import org.checkerframework.checker.nullness.qual.PolyNull;
@@ -960,7 +961,7 @@ public V setValue(@ParametricNullness V value) {
   }
 
   @Override
-  public int size() {
+  public @NonNegative int size() {
     Map<K, V> delegate = delegateOrNull();
     return (delegate != null) ? delegate.size() : size;
   }
diff --git a/guava/src/com/google/common/collect/CompactHashSet.java b/guava/src/com/google/common/collect/CompactHashSet.java
index 5b0c11f4566f..7b10c5a4e8d6 100644
--- a/guava/src/com/google/common/collect/CompactHashSet.java
+++ b/guava/src/com/google/common/collect/CompactHashSet.java
@@ -46,6 +46,7 @@
 import java.util.Spliterators;
 import java.util.function.Consumer;
 import javax.annotation.CheckForNull;
+import org.checkerframework.checker.index.qual.NonNegative;
 import org.checkerframework.checker.nullness.qual.Nullable;
 import org.checkerframework.checker.nullness.qual.PolyNull;
 import org.checkerframework.checker.signedness.qual.PolySigned;
@@ -619,7 +620,7 @@ public void forEach(Consumer<? super E> action) {
   }
 
   @Override
-  public int size() {
+  public @NonNegative int size() {
     Set<E> delegate = delegateOrNull();
     return (delegate != null) ? delegate.size() : size;
   }
diff --git a/guava/src/com/google/common/collect/ConcurrentHashMultiset.java b/guava/src/com/google/common/collect/ConcurrentHashMultiset.java
index 4f4761454f34..665c4e115e74 100644
--- a/guava/src/com/google/common/collect/ConcurrentHashMultiset.java
+++ b/guava/src/com/google/common/collect/ConcurrentHashMultiset.java
@@ -160,7 +160,7 @@ public static <E> ConcurrentHashMultiset<E> create(ConcurrentMap<E, AtomicIntege
    */
   @Pure
   @Override
-  public int size() {
+  public @NonNegative int size() {
     long sum = 0L;
     for (AtomicInteger value : countMap.values()) {
       sum += value.get();
@@ -602,7 +602,7 @@ private List<Multiset.Entry<E>> snapshot() {
 
   @Pure
   @Override
-  public int size() { return super.size(); }
+  public @NonNegative int size() { return super.size(); }
 
   @Pure
   @Override
diff --git a/guava/src/com/google/common/collect/DenseImmutableTable.java b/guava/src/com/google/common/collect/DenseImmutableTable.java
index 9de77c57f213..9c20b45089a2 100644
--- a/guava/src/com/google/common/collect/DenseImmutableTable.java
+++ b/guava/src/com/google/common/collect/DenseImmutableTable.java
@@ -22,6 +22,7 @@
 import com.google.j2objc.annotations.WeakOuter;
 import java.util.Map;
 import javax.annotation.CheckForNull;
+import org.checkerframework.checker.index.qual.NonNegative;
 import org.checkerframework.checker.nullness.qual.Nullable;
 
 /** A {@code RegularImmutableTable} optimized for dense data. */
@@ -114,7 +115,7 @@ ImmutableSet<K> createKeySet() {
     }
 
     @Override
-    public int size() {
+    public @NonNegative int size() {
       return size;
     }
 
diff --git a/guava/src/com/google/common/collect/DescendingImmutableSortedMultiset.java b/guava/src/com/google/common/collect/DescendingImmutableSortedMultiset.java
index dd0a25df6c97..f8c9b0c7bbf3 100644
--- a/guava/src/com/google/common/collect/DescendingImmutableSortedMultiset.java
+++ b/guava/src/com/google/common/collect/DescendingImmutableSortedMultiset.java
@@ -52,7 +52,7 @@ public Entry<E> lastEntry() {
   }
 
   @Override
-  public int size() {
+  public @NonNegative int size() {
     return forward.size();
   }
 
diff --git a/guava/src/com/google/common/collect/DescendingImmutableSortedSet.java b/guava/src/com/google/common/collect/DescendingImmutableSortedSet.java
index 88c7d6b5cca0..be03268fa17e 100644
--- a/guava/src/com/google/common/collect/DescendingImmutableSortedSet.java
+++ b/guava/src/com/google/common/collect/DescendingImmutableSortedSet.java
@@ -18,6 +18,7 @@
 
 import com.google.common.annotations.GwtIncompatible;
 import javax.annotation.CheckForNull;
+import org.checkerframework.checker.index.qual.NonNegative;
 
 /**
  * Skeletal implementation of {@link ImmutableSortedSet#descendingSet()}.
@@ -40,7 +41,7 @@ public boolean contains(@CheckForNull Object object) {
   }
 
   @Override
-  public int size() {
+  public @NonNegative int size() {
     return forward.size();
   }
 
diff --git a/guava/src/com/google/common/collect/DescendingMultiset.java b/guava/src/com/google/common/collect/DescendingMultiset.java
index 6481eb06305e..e57fa6c88c8a 100644
--- a/guava/src/com/google/common/collect/DescendingMultiset.java
+++ b/guava/src/com/google/common/collect/DescendingMultiset.java
@@ -23,6 +23,7 @@
 import java.util.NavigableSet;
 import java.util.Set;
 import javax.annotation.CheckForNull;
+import org.checkerframework.checker.index.qual.NonNegative;
 import org.checkerframework.checker.nullness.qual.Nullable;
 import org.checkerframework.checker.nullness.qual.PolyNull;
 import org.checkerframework.checker.signedness.qual.PolySigned;
@@ -140,7 +141,7 @@ public Iterator<Entry<E>> iterator() {
       }
 
       @Override
-      public int size() {
+      public @NonNegative int size() {
         return forwardMultiset().entrySet().size();
       }
     }
diff --git a/guava/src/com/google/common/collect/EmptyContiguousSet.java b/guava/src/com/google/common/collect/EmptyContiguousSet.java
index 50d7b126a27a..095d981de8a2 100644
--- a/guava/src/com/google/common/collect/EmptyContiguousSet.java
+++ b/guava/src/com/google/common/collect/EmptyContiguousSet.java
@@ -19,6 +19,7 @@
 import java.util.NoSuchElementException;
 import java.util.Set;
 import javax.annotation.CheckForNull;
+import org.checkerframework.checker.index.qual.NonNegative;
 
 /**
  * An empty contiguous set.
@@ -44,7 +45,7 @@ public C last() {
   }
 
   @Override
-  public int size() {
+  public @NonNegative int size() {
     return 0;
   }
 
diff --git a/guava/src/com/google/common/collect/EnumMultiset.java b/guava/src/com/google/common/collect/EnumMultiset.java
index 7421f222c48c..2ca1e895ca1c 100644
--- a/guava/src/com/google/common/collect/EnumMultiset.java
+++ b/guava/src/com/google/common/collect/EnumMultiset.java
@@ -127,7 +127,7 @@ int distinctElements() {
   }
 
   @Override
-  public int size() {
+  public @NonNegative int size() {
     return Ints.saturatedCast(size);
   }
 
diff --git a/guava/src/com/google/common/collect/FilteredEntryMultimap.java b/guava/src/com/google/common/collect/FilteredEntryMultimap.java
index 9165711f059f..becc1ddaccf8 100644
--- a/guava/src/com/google/common/collect/FilteredEntryMultimap.java
+++ b/guava/src/com/google/common/collect/FilteredEntryMultimap.java
@@ -34,6 +34,7 @@
 import java.util.Map.Entry;
 import java.util.Set;
 import javax.annotation.CheckForNull;
+import org.checkerframework.checker.index.qual.NonNegative;
 import org.checkerframework.checker.nullness.qual.Nullable;
 import org.checkerframework.checker.signedness.qual.UnknownSignedness;
 
@@ -288,7 +289,7 @@ public boolean retainAll(Collection<?> c) {
         }
 
         @Override
-        public int size() {
+        public @NonNegative int size() {
           return Iterators.size(iterator());
         }
       }
@@ -393,7 +394,7 @@ public Iterator<Multiset.Entry<K>> iterator() {
         }
 
         @Override
-        public int size() {
+        public @NonNegative int size() {
           return FilteredEntryMultimap.this.keySet().size();
         }
 
diff --git a/guava/src/com/google/common/collect/FilteredMultimapValues.java b/guava/src/com/google/common/collect/FilteredMultimapValues.java
index 89480018dea1..de500e326bff 100644
--- a/guava/src/com/google/common/collect/FilteredMultimapValues.java
+++ b/guava/src/com/google/common/collect/FilteredMultimapValues.java
@@ -26,6 +26,7 @@
 import java.util.Iterator;
 import java.util.Map.Entry;
 import javax.annotation.CheckForNull;
+import org.checkerframework.checker.index.qual.NonNegative;
 import org.checkerframework.checker.nullness.qual.Nullable;
 import org.checkerframework.checker.signedness.qual.UnknownSignedness;
 
@@ -55,7 +56,7 @@ public boolean contains(@CheckForNull Object o) {
   }
 
   @Override
-  public int size() {
+  public @NonNegative int size() {
     return multimap.size();
   }
 
diff --git a/guava/src/com/google/common/collect/ForwardingMap.java b/guava/src/com/google/common/collect/ForwardingMap.java
index 30715bf76b4a..149b205a4c3c 100644
--- a/guava/src/com/google/common/collect/ForwardingMap.java
+++ b/guava/src/com/google/common/collect/ForwardingMap.java
@@ -25,6 +25,7 @@
 import java.util.Map;
 import java.util.Set;
 import javax.annotation.CheckForNull;
+import org.checkerframework.checker.index.qual.NonNegative;
 import org.checkerframework.checker.nullness.qual.KeyFor;
 import org.checkerframework.checker.nullness.qual.Nullable;
 import org.checkerframework.checker.signedness.qual.UnknownSignedness;
@@ -76,7 +77,7 @@ protected ForwardingMap() {}
   @Pure
   @Override
   @SuppressWarnings("index:overriding.return")
-  public int size() {
+  public @NonNegative int size() {
     return delegate().size();
   }
 
diff --git a/guava/src/com/google/common/collect/HashBiMap.java b/guava/src/com/google/common/collect/HashBiMap.java
index f7969134ef3c..6e2ecd5fffa1 100644
--- a/guava/src/com/google/common/collect/HashBiMap.java
+++ b/guava/src/com/google/common/collect/HashBiMap.java
@@ -41,6 +41,7 @@
 import java.util.function.BiConsumer;
 import java.util.function.BiFunction;
 import javax.annotation.CheckForNull;
+import org.checkerframework.checker.index.qual.NonNegative;
 import org.checkerframework.checker.nullness.qual.KeyFor;
 import org.checkerframework.checker.nullness.qual.Nullable;
 import org.checkerframework.checker.signedness.qual.UnknownSignedness;
@@ -434,7 +435,7 @@ public void clear() {
   }
 
   @Override
-  public int size() {
+  public @NonNegative int size() {
     return size;
   }
 
@@ -609,7 +610,7 @@ BiMap<K, V> forward() {
     }
 
     @Override
-    public int size() {
+    public @NonNegative int size() {
       return size;
     }
 
diff --git a/guava/src/com/google/common/collect/ImmutableAsList.java b/guava/src/com/google/common/collect/ImmutableAsList.java
index 19edf62415c7..f3dfdecaa372 100644
--- a/guava/src/com/google/common/collect/ImmutableAsList.java
+++ b/guava/src/com/google/common/collect/ImmutableAsList.java
@@ -23,6 +23,7 @@
 import java.io.Serializable;
 import javax.annotation.CheckForNull;
 
+import org.checkerframework.checker.index.qual.NonNegative;
 import org.checkerframework.checker.signedness.qual.UnknownSignedness;
 
 /**
@@ -46,7 +47,7 @@ public boolean contains(@CheckForNull @UnknownSignedness Object target) {
   }
 
   @Override
-  public int size() {
+  public @NonNegative int size() {
     return delegateCollection().size();
   }
 
diff --git a/guava/src/com/google/common/collect/ImmutableEnumMap.java b/guava/src/com/google/common/collect/ImmutableEnumMap.java
index dceddb34ed20..163a9c723422 100644
--- a/guava/src/com/google/common/collect/ImmutableEnumMap.java
+++ b/guava/src/com/google/common/collect/ImmutableEnumMap.java
@@ -25,6 +25,7 @@
 import java.util.Spliterator;
 import java.util.function.BiConsumer;
 import javax.annotation.CheckForNull;
+import org.checkerframework.checker.index.qual.NonNegative;
 import org.checkerframework.checker.signedness.qual.UnknownSignedness;
 
 /**
@@ -66,7 +67,7 @@ Spliterator<K> keySpliterator() {
   }
 
   @Override
-  public int size() {
+  public @NonNegative int size() {
     return delegate.size();
   }
 
diff --git a/guava/src/com/google/common/collect/ImmutableEnumSet.java b/guava/src/com/google/common/collect/ImmutableEnumSet.java
index aefeba2b619f..3468009804ad 100644
--- a/guava/src/com/google/common/collect/ImmutableEnumSet.java
+++ b/guava/src/com/google/common/collect/ImmutableEnumSet.java
@@ -24,6 +24,7 @@
 import java.util.Spliterator;
 import java.util.function.Consumer;
 import javax.annotation.CheckForNull;
+import org.checkerframework.checker.index.qual.NonNegative;
 import org.checkerframework.checker.nullness.qual.Nullable;
 import org.checkerframework.dataflow.qual.Pure;
 import org.checkerframework.framework.qual.AnnotatedFor;
@@ -86,7 +87,7 @@ public void forEach(Consumer<? super E> action) {
   }
 
   @Override
-  public int size() {
+  public @NonNegative int size() {
     return delegate.size();
   }
 
diff --git a/guava/src/com/google/common/collect/ImmutableList.java b/guava/src/com/google/common/collect/ImmutableList.java
index 7ec268d28276..b83219680929 100644
--- a/guava/src/com/google/common/collect/ImmutableList.java
+++ b/guava/src/com/google/common/collect/ImmutableList.java
@@ -46,6 +46,7 @@
 import java.util.function.UnaryOperator;
 import java.util.stream.Collector;
 import javax.annotation.CheckForNull;
+import org.checkerframework.checker.index.qual.NonNegative;
 import org.checkerframework.checker.nullness.qual.NonNull;
 import org.checkerframework.checker.nullness.qual.Nullable;
 import org.checkerframework.checker.signedness.qual.UnknownSignedness;
@@ -492,7 +493,7 @@ class SubList extends ImmutableList<E> {
     }
 
     @Override
-    public int size() {
+    public @NonNegative int size() {
       return length;
     }
 
@@ -685,7 +686,7 @@ public E get(int index) {
     }
 
     @Override
-    public int size() {
+    public @NonNegative int size() {
       return forwardList.size();
     }
 
diff --git a/guava/src/com/google/common/collect/ImmutableMap.java b/guava/src/com/google/common/collect/ImmutableMap.java
index 8c6dc760a7df..36cc47e8e3fe 100644
--- a/guava/src/com/google/common/collect/ImmutableMap.java
+++ b/guava/src/com/google/common/collect/ImmutableMap.java
@@ -51,6 +51,7 @@
 import java.util.stream.Collector;
 import java.util.stream.Collectors;
 import javax.annotation.CheckForNull;
+import org.checkerframework.checker.index.qual.NonNegative;
 import org.checkerframework.checker.nullness.qual.KeyFor;
 import org.checkerframework.checker.nullness.qual.MonotonicNonNull;
 import org.checkerframework.checker.nullness.qual.NonNull;
@@ -1115,7 +1116,7 @@ private final class MapViewOfValuesAsSingletonSets
       extends IteratorBasedImmutableMap<K, ImmutableSet<V>> {
 
     @Override
-    public int size() {
+    public @NonNegative int size() {
       return ImmutableMap.this.size();
     }
 
diff --git a/guava/src/com/google/common/collect/ImmutableMapEntrySet.java b/guava/src/com/google/common/collect/ImmutableMapEntrySet.java
index 5eb3853e62ff..2329d2eb52d0 100644
--- a/guava/src/com/google/common/collect/ImmutableMapEntrySet.java
+++ b/guava/src/com/google/common/collect/ImmutableMapEntrySet.java
@@ -23,6 +23,7 @@
 import java.util.Spliterator;
 import java.util.function.Consumer;
 import javax.annotation.CheckForNull;
+import org.checkerframework.checker.index.qual.NonNegative;
 import org.checkerframework.checker.nullness.qual.Nullable;
 import org.checkerframework.checker.signedness.qual.UnknownSignedness;
 
@@ -85,7 +86,7 @@ ImmutableList<Entry<K, V>> createAsList() {
   abstract ImmutableMap<K, V> map();
 
   @Override
-  public int size() {
+  public @NonNegative int size() {
     return map().size();
   }
 
diff --git a/guava/src/com/google/common/collect/ImmutableMapKeySet.java b/guava/src/com/google/common/collect/ImmutableMapKeySet.java
index d10ee10e7a8f..e41a1942d158 100644
--- a/guava/src/com/google/common/collect/ImmutableMapKeySet.java
+++ b/guava/src/com/google/common/collect/ImmutableMapKeySet.java
@@ -24,6 +24,7 @@
 import java.util.Spliterator;
 import java.util.function.Consumer;
 import javax.annotation.CheckForNull;
+import org.checkerframework.checker.index.qual.NonNegative;
 
 /**
  * {@code keySet()} implementation for {@link ImmutableMap}.
@@ -41,7 +42,7 @@ final class ImmutableMapKeySet<K, V> extends IndexedImmutableSet<K> {
   }
 
   @Override
-  public int size() {
+  public @NonNegative int size() {
     return map.size();
   }
 
diff --git a/guava/src/com/google/common/collect/ImmutableMapValues.java b/guava/src/com/google/common/collect/ImmutableMapValues.java
index 702191c6499d..f23f510212cc 100644
--- a/guava/src/com/google/common/collect/ImmutableMapValues.java
+++ b/guava/src/com/google/common/collect/ImmutableMapValues.java
@@ -25,6 +25,7 @@
 import java.util.Spliterator;
 import java.util.function.Consumer;
 import javax.annotation.CheckForNull;
+import org.checkerframework.checker.index.qual.NonNegative;
 
 /**
  * {@code values()} implementation for {@link ImmutableMap}.
@@ -42,7 +43,7 @@ final class ImmutableMapValues<K, V> extends ImmutableCollection<V> {
   }
 
   @Override
-  public int size() {
+  public @NonNegative int size() {
     return map.size();
   }
 
diff --git a/guava/src/com/google/common/collect/ImmutableMultimap.java b/guava/src/com/google/common/collect/ImmutableMultimap.java
index 98c381205e24..12eec7742bf8 100644
--- a/guava/src/com/google/common/collect/ImmutableMultimap.java
+++ b/guava/src/com/google/common/collect/ImmutableMultimap.java
@@ -576,7 +576,7 @@ boolean isPartialView() {
 
     @Pure
     @Override
-    public int size() {
+    public @NonNegative int size() {
       return multimap.size();
     }
 
@@ -679,7 +679,7 @@ public ImmutableSet<K> elementSet() {
     }
 
     @Override
-    public int size() {
+    public @NonNegative int size() {
       return ImmutableMultimap.this.size();
     }
 
@@ -778,7 +778,7 @@ int copyIntoArray(@Nullable Object[] dst, int offset) {
 
     @Pure
     @Override
-    public int size() {
+    public @NonNegative int size() {
       return multimap.size();
     }
 
diff --git a/guava/src/com/google/common/collect/ImmutableMultiset.java b/guava/src/com/google/common/collect/ImmutableMultiset.java
index 34d3ba9be2c9..041184afbb84 100644
--- a/guava/src/com/google/common/collect/ImmutableMultiset.java
+++ b/guava/src/com/google/common/collect/ImmutableMultiset.java
@@ -36,6 +36,7 @@
 import java.util.function.ToIntFunction;
 import java.util.stream.Collector;
 import javax.annotation.CheckForNull;
+import org.checkerframework.checker.index.qual.NonNegative;
 import org.checkerframework.checker.nullness.qual.Nullable;
 import org.checkerframework.checker.signedness.qual.UnknownSignedness;
 import org.checkerframework.dataflow.qual.Pure;
@@ -390,7 +391,7 @@ Entry<E> get(int index) {
 
     @Pure
     @Override
-    public int size() {
+    public @NonNegative int size() {
       return elementSet().size();
     }
 
@@ -622,7 +623,7 @@ boolean isPartialView() {
     }
 
     @Override
-    public int size() {
+    public @NonNegative int size() {
       return entries.size();
     }
   }
diff --git a/guava/src/com/google/common/collect/ImmutableRangeMap.java b/guava/src/com/google/common/collect/ImmutableRangeMap.java
index e1979ab65fe9..f2d69a2932ad 100644
--- a/guava/src/com/google/common/collect/ImmutableRangeMap.java
+++ b/guava/src/com/google/common/collect/ImmutableRangeMap.java
@@ -35,6 +35,7 @@
 import java.util.function.Function;
 import java.util.stream.Collector;
 import javax.annotation.CheckForNull;
+import org.checkerframework.checker.index.qual.NonNegative;
 import org.checkerframework.checker.nullness.qual.Nullable;
 
 /**
@@ -353,7 +354,7 @@ public ImmutableRangeMap<K, V> subRangeMap(final Range<K> range) {
     ImmutableList<Range<K>> subRanges =
         new ImmutableList<Range<K>>() {
           @Override
-          public int size() {
+          public @NonNegative int size() {
             return len;
           }
 
diff --git a/guava/src/com/google/common/collect/ImmutableRangeSet.java b/guava/src/com/google/common/collect/ImmutableRangeSet.java
index f279aae0c56b..073707a48573 100644
--- a/guava/src/com/google/common/collect/ImmutableRangeSet.java
+++ b/guava/src/com/google/common/collect/ImmutableRangeSet.java
@@ -38,6 +38,7 @@
 import java.util.Set;
 import java.util.stream.Collector;
 import javax.annotation.CheckForNull;
+import org.checkerframework.checker.index.qual.NonNegative;
 
 /**
  * A {@link RangeSet} whose contents will never change, with many other important properties
@@ -338,7 +339,7 @@ private final class ComplementRanges extends ImmutableList<Range<C>> {
     }
 
     @Override
-    public int size() {
+    public @NonNegative int size() {
       return size;
     }
 
@@ -468,7 +469,7 @@ private ImmutableList<Range<C>> intersectRanges(final Range<C> range) {
     } else {
       return new ImmutableList<Range<C>>() {
         @Override
-        public int size() {
+        public @NonNegative int size() {
           return length;
         }
 
@@ -557,7 +558,7 @@ private final class AsSet extends ImmutableSortedSet<C> {
     @CheckForNull private transient Integer size;
 
     @Override
-    public int size() {
+    public @NonNegative int size() {
       // racy single-check idiom
       Integer result = size;
       if (result == null) {
diff --git a/guava/src/com/google/common/collect/ImmutableSetMultimap.java b/guava/src/com/google/common/collect/ImmutableSetMultimap.java
index af1e91ebf6c3..9cf1ee0b5c16 100644
--- a/guava/src/com/google/common/collect/ImmutableSetMultimap.java
+++ b/guava/src/com/google/common/collect/ImmutableSetMultimap.java
@@ -40,6 +40,7 @@
 import java.util.stream.Collector;
 import java.util.stream.Stream;
 import javax.annotation.CheckForNull;
+import org.checkerframework.checker.index.qual.NonNegative;
 import org.checkerframework.checker.nullness.qual.Nullable;
 import org.checkerframework.checker.signedness.qual.UnknownSignedness;
 import org.checkerframework.dataflow.qual.SideEffectFree;
@@ -546,7 +547,7 @@ public boolean contains(@CheckForNull @UnknownSignedness Object object) {
     }
 
     @Override
-    public int size() {
+    public @NonNegative int size() {
       return multimap.size();
     }
 
diff --git a/guava/src/com/google/common/collect/ImmutableSortedMap.java b/guava/src/com/google/common/collect/ImmutableSortedMap.java
index edcfcf46ba89..d008faa8ebb6 100644
--- a/guava/src/com/google/common/collect/ImmutableSortedMap.java
+++ b/guava/src/com/google/common/collect/ImmutableSortedMap.java
@@ -41,6 +41,7 @@
 import java.util.stream.Collector;
 import java.util.stream.Collectors;
 import javax.annotation.CheckForNull;
+import org.checkerframework.checker.index.qual.NonNegative;
 import org.checkerframework.checker.nullness.qual.KeyFor;
 import org.checkerframework.checker.nullness.qual.Nullable;
 import org.checkerframework.checker.signedness.qual.UnknownSignedness;
@@ -788,7 +789,7 @@ public final ImmutableSortedMap<K, V> buildKeepingLast() {
 
   @Pure
   @Override
-  public int size() {
+  public @NonNegative int size() {
     return valueList.size();
   }
 
diff --git a/guava/src/com/google/common/collect/IndexedImmutableSet.java b/guava/src/com/google/common/collect/IndexedImmutableSet.java
index 20dfacbab86a..05bd8b127d59 100644
--- a/guava/src/com/google/common/collect/IndexedImmutableSet.java
+++ b/guava/src/com/google/common/collect/IndexedImmutableSet.java
@@ -22,6 +22,7 @@
 import com.google.common.annotations.GwtIncompatible;
 import java.util.Spliterator;
 import java.util.function.Consumer;
+import org.checkerframework.checker.index.qual.NonNegative;
 import org.checkerframework.checker.nullness.qual.Nullable;
 
 @GwtCompatible(emulated = true)
@@ -68,7 +69,7 @@ boolean isPartialView() {
       }
 
       @Override
-      public int size() {
+      public @NonNegative int size() {
         return IndexedImmutableSet.this.size();
       }
 
diff --git a/guava/src/com/google/common/collect/JdkBackedImmutableBiMap.java b/guava/src/com/google/common/collect/JdkBackedImmutableBiMap.java
index f126fdea3baf..5a8b1d3c3b78 100644
--- a/guava/src/com/google/common/collect/JdkBackedImmutableBiMap.java
+++ b/guava/src/com/google/common/collect/JdkBackedImmutableBiMap.java
@@ -24,6 +24,7 @@
 import com.google.j2objc.annotations.WeakOuter;
 import java.util.Map;
 import javax.annotation.CheckForNull;
+import org.checkerframework.checker.index.qual.NonNegative;
 import org.checkerframework.checker.nullness.qual.Nullable;
 
 /**
@@ -66,7 +67,7 @@ private JdkBackedImmutableBiMap(
   }
 
   @Override
-  public int size() {
+  public @NonNegative int size() {
     return entries.size();
   }
 
@@ -99,7 +100,7 @@ boolean isPartialView() {
     }
 
     @Override
-    public int size() {
+    public @NonNegative int size() {
       return entries.size();
     }
   }
diff --git a/guava/src/com/google/common/collect/JdkBackedImmutableMap.java b/guava/src/com/google/common/collect/JdkBackedImmutableMap.java
index 222c4deb8ae5..8f1d78819e92 100644
--- a/guava/src/com/google/common/collect/JdkBackedImmutableMap.java
+++ b/guava/src/com/google/common/collect/JdkBackedImmutableMap.java
@@ -25,6 +25,7 @@
 import java.util.Map;
 import java.util.function.BiConsumer;
 import javax.annotation.CheckForNull;
+import org.checkerframework.checker.index.qual.NonNegative;
 import org.checkerframework.checker.nullness.qual.Nullable;
 
 /**
@@ -95,7 +96,7 @@ static <K, V> ImmutableMap<K, V> create(
   }
 
   @Override
-  public int size() {
+  public @NonNegative int size() {
     return entries.size();
   }
 
diff --git a/guava/src/com/google/common/collect/JdkBackedImmutableMultiset.java b/guava/src/com/google/common/collect/JdkBackedImmutableMultiset.java
index 9debeff6d22e..82472963f5a8 100644
--- a/guava/src/com/google/common/collect/JdkBackedImmutableMultiset.java
+++ b/guava/src/com/google/common/collect/JdkBackedImmutableMultiset.java
@@ -87,7 +87,7 @@ boolean isPartialView() {
   }
 
   @Override
-  public int size() {
+  public @NonNegative int size() {
     return Ints.saturatedCast(size);
   }
 }
diff --git a/guava/src/com/google/common/collect/JdkBackedImmutableSet.java b/guava/src/com/google/common/collect/JdkBackedImmutableSet.java
index c00167713cc9..6423792fab69 100644
--- a/guava/src/com/google/common/collect/JdkBackedImmutableSet.java
+++ b/guava/src/com/google/common/collect/JdkBackedImmutableSet.java
@@ -17,6 +17,7 @@
 import com.google.common.annotations.GwtCompatible;
 import java.util.Set;
 import javax.annotation.CheckForNull;
+import org.checkerframework.checker.index.qual.NonNegative;
 
 /**
  * ImmutableSet implementation backed by a JDK HashSet, used to defend against apparent hash
@@ -52,7 +53,7 @@ boolean isPartialView() {
   }
 
   @Override
-  public int size() {
+  public @NonNegative int size() {
     return delegateList.size();
   }
 }
diff --git a/guava/src/com/google/common/collect/LinkedHashMultimap.java b/guava/src/com/google/common/collect/LinkedHashMultimap.java
index 5583f2844662..61c029a88b61 100644
--- a/guava/src/com/google/common/collect/LinkedHashMultimap.java
+++ b/guava/src/com/google/common/collect/LinkedHashMultimap.java
@@ -42,6 +42,7 @@
 import java.util.Spliterators;
 import java.util.function.Consumer;
 import javax.annotation.CheckForNull;
+import org.checkerframework.checker.index.qual.NonNegative;
 import org.checkerframework.checker.nullness.qual.KeyFor;
 import org.checkerframework.checker.nullness.qual.Nullable;
 import org.checkerframework.checker.signedness.qual.UnknownSignedness;
@@ -468,7 +469,7 @@ public void forEach(Consumer<? super V> action) {
     }
 
     @Override
-    public int size() {
+    public @NonNegative int size() {
       return size;
     }
 
diff --git a/guava/src/com/google/common/collect/LinkedListMultimap.java b/guava/src/com/google/common/collect/LinkedListMultimap.java
index a2fcff1e7c60..7499a24ea2b8 100644
--- a/guava/src/com/google/common/collect/LinkedListMultimap.java
+++ b/guava/src/com/google/common/collect/LinkedListMultimap.java
@@ -42,6 +42,7 @@
 import java.util.Set;
 import java.util.function.Consumer;
 import javax.annotation.CheckForNull;
+import org.checkerframework.checker.index.qual.NonNegative;
 import org.checkerframework.checker.nullness.qual.Nullable;
 import org.checkerframework.checker.signedness.qual.UnknownSignedness;
 import org.checkerframework.dataflow.qual.Pure;
@@ -412,12 +413,12 @@ public Node<K, V> previous() {
     }
 
     @Override
-    public int nextIndex() {
+    public @NonNegative int nextIndex() {
       return nextIndex;
     }
 
     @Override
-    public int previousIndex() {
+    public @NonNegative int previousIndex() {
       return nextIndex - 1;
     }
 
@@ -561,12 +562,12 @@ public V previous() {
     }
 
     @Override
-    public int nextIndex() {
+    public @NonNegative int nextIndex() {
       return nextIndex;
     }
 
     @Override
-    public int previousIndex() {
+    public @NonNegative int previousIndex() {
       return nextIndex - 1;
     }
 
@@ -725,7 +726,7 @@ public List<V> get(@ParametricNullness final K key) {
     return new AbstractSequentialList<V>() {
       @Pure
       @Override
-      public int size() {
+      public @NonNegative int size() {
         KeyList<K, V> keyList = keyToKeyList.get(key);
         return (keyList == null) ? 0 : keyList.count;
       }
@@ -742,7 +743,7 @@ Set<K> createKeySet() {
     @WeakOuter
     class KeySetImpl extends Sets.ImprovedAbstractSet<K> {
       @Override
-      public int size() {
+      public @NonNegative int size() {
         return keyToKeyList.size();
       }
 
@@ -789,7 +790,7 @@ List<V> createValues() {
     @WeakOuter
     class ValuesImpl extends AbstractSequentialList<V> {
       @Override
-      public int size() {
+      public @NonNegative int size() {
         return size;
       }
 
@@ -840,7 +841,7 @@ List<Entry<K, V>> createEntries() {
     @WeakOuter
     class EntriesImpl extends AbstractSequentialList<Entry<K, V>> {
       @Override
-      public int size() {
+      public @NonNegative int size() {
         return size;
       }
 
diff --git a/guava/src/com/google/common/collect/Lists.java b/guava/src/com/google/common/collect/Lists.java
index 8e4983d8756a..3e3df72119cb 100644
--- a/guava/src/com/google/common/collect/Lists.java
+++ b/guava/src/com/google/common/collect/Lists.java
@@ -50,6 +50,7 @@
 import java.util.concurrent.CopyOnWriteArrayList;
 import java.util.function.Predicate;
 import javax.annotation.CheckForNull;
+import org.checkerframework.checker.index.qual.NonNegative;
 import org.checkerframework.checker.nullness.qual.Nullable;
 import org.checkerframework.checker.signedness.qual.UnknownSignedness;
 import org.checkerframework.dataflow.qual.Pure;
@@ -331,7 +332,7 @@ private static class OnePlusArrayList<E extends @Nullable Object> extends Abstra
 
     @Pure
     @Override
-    public int size() {
+    public @NonNegative int size() {
       return IntMath.saturatedAdd(rest.length, 1);
     }
 
@@ -361,7 +362,7 @@ private static class TwoPlusArrayList<E extends @Nullable Object> extends Abstra
 
     @Pure
     @Override
-    public int size() {
+    public @NonNegative int size() {
       return IntMath.saturatedAdd(rest.length, 2);
     }
 
@@ -566,7 +567,7 @@ public void clear() {
 
     @Pure
     @Override
-    public int size() {
+    public @NonNegative int size() {
       return fromList.size();
     }
 
@@ -654,7 +655,7 @@ public T remove(int index) {
 
     @Pure
     @Override
-    public int size() {
+    public @NonNegative int size() {
       return fromList.size();
     }
 
@@ -703,7 +704,7 @@ public List<T> get(int index) {
 
     @Pure
     @Override
-    public int size() {
+    public @NonNegative int size() {
       return IntMath.divide(list.size(), size, RoundingMode.CEILING);
     }
 
@@ -781,7 +782,7 @@ public Character get(int index) {
     }
 
     @Override
-    public int size() {
+    public @NonNegative int size() {
       return string.length();
     }
   }
@@ -800,7 +801,7 @@ public Character get(int index) {
     }
 
     @Override
-    public int size() {
+    public @NonNegative int size() {
       return sequence.length();
     }
   }
@@ -889,7 +890,7 @@ public T get(int index) {
     }
 
     @Override
-    public int size() {
+    public @NonNegative int size() {
       return forwardList.size();
     }
 
@@ -940,7 +941,7 @@ public T next() {
         }
 
         @Override
-        public int nextIndex() {
+        public @NonNegative int nextIndex() {
           return reversePosition(forwardIterator.nextIndex());
         }
 
@@ -955,7 +956,7 @@ public T previous() {
         }
 
         @Override
-        public int previousIndex() {
+        public @NonNegative int previousIndex() {
           return nextIndex() - 1;
         }
 
@@ -1172,7 +1173,7 @@ public boolean contains(@CheckForNull @UnknownSignedness Object o) {
     }
 
     @Override
-    public int size() {
+    public @NonNegative int size() {
       return backingList.size();
     }
   }
diff --git a/guava/src/com/google/common/collect/MapMakerInternalMap.java b/guava/src/com/google/common/collect/MapMakerInternalMap.java
index 89e99f9d0c37..68a1ef15c1b7 100644
--- a/guava/src/com/google/common/collect/MapMakerInternalMap.java
+++ b/guava/src/com/google/common/collect/MapMakerInternalMap.java
@@ -47,6 +47,7 @@
 import java.util.concurrent.atomic.AtomicInteger;
 import java.util.concurrent.atomic.AtomicReferenceArray;
 import java.util.concurrent.locks.ReentrantLock;
+import org.checkerframework.checker.index.qual.NonNegative;
 import org.checkerframework.checker.nullness.qual.KeyFor;
 import org.checkerframework.checker.nullness.qual.Nullable;
 import org.checkerframework.checker.nullness.qual.PolyNull;
@@ -2329,7 +2330,7 @@ public boolean isEmpty() {
   }
 
   @Override
-  public int size() {
+  public @NonNegative int size() {
     Segment<K, V, E, S>[] segments = this.segments;
     long sum = 0;
     for (int i = 0; i < segments.length; ++i) {
@@ -2693,7 +2694,7 @@ public Iterator<K> iterator() {
     }
 
     @Override
-    public int size() {
+    public @NonNegative int size() {
       return MapMakerInternalMap.this.size();
     }
 
@@ -2727,7 +2728,7 @@ public Iterator<V> iterator() {
     }
 
     @Override
-    public int size() {
+    public @NonNegative int size() {
       return MapMakerInternalMap.this.size();
     }
 
@@ -2795,7 +2796,7 @@ public boolean remove(@UnknownSignedness Object o) {
     }
 
     @Override
-    public int size() {
+    public @NonNegative int size() {
       return MapMakerInternalMap.this.size();
     }
 
diff --git a/guava/src/com/google/common/collect/Maps.java b/guava/src/com/google/common/collect/Maps.java
index d9c111bb1612..93c138921ca7 100644
--- a/guava/src/com/google/common/collect/Maps.java
+++ b/guava/src/com/google/common/collect/Maps.java
@@ -71,6 +71,7 @@
 import java.util.function.Consumer;
 import java.util.stream.Collector;
 import javax.annotation.CheckForNull;
+import org.checkerframework.checker.index.qual.NonNegative;
 import org.checkerframework.checker.nullness.qual.KeyFor;
 import org.checkerframework.checker.nullness.qual.Nullable;
 import org.checkerframework.checker.nullness.qual.PolyNull;
@@ -939,7 +940,7 @@ Collection<V> createValues() {
     }
 
     @Override
-    public int size() {
+    public @NonNegative int size() {
       return backingSet().size();
     }
 
@@ -1160,7 +1161,7 @@ Iterator<Entry<K, V>> descendingEntryIterator() {
     }
 
     @Override
-    public int size() {
+    public @NonNegative int size() {
       return set.size();
     }
 
@@ -2222,7 +2223,7 @@ static class TransformedEntriesMap<
     }
 
     @Override
-    public int size() {
+    public @NonNegative int size() {
       return fromMap.size();
     }
 
@@ -3385,7 +3386,7 @@ Iterator<Entry<K, V>> descendingEntryIterator() {
     }
 
     @Override
-    public int size() {
+    public @NonNegative int size() {
       return filteredDelegate.size();
     }
 
@@ -3876,7 +3877,7 @@ abstract static class IteratorBasedAbstractMap<
           K extends @Nullable Object, V extends @Nullable Object>
       extends AbstractMap<K, V> {
     @Override
-    public abstract int size();
+    public abstract @NonNegative int size();
 
     abstract Iterator<Entry<K, V>> entryIterator();
 
@@ -4069,7 +4070,7 @@ public void forEach(Consumer<? super K> action) {
     }
 
     @Override
-    public int size() {
+    public @NonNegative int size() {
       return map().size();
     }
 
@@ -4316,7 +4317,7 @@ public boolean retainAll(Collection<?> c) {
     }
 
     @Override
-    public int size() {
+    public @NonNegative int size() {
       return map().size();
     }
 
@@ -4341,7 +4342,7 @@ abstract static class EntrySet<K extends @Nullable Object, V extends @Nullable O
     abstract Map<K, V> map();
 
     @Override
-    public int size() {
+    public @NonNegative int size() {
       return map().size();
     }
 
diff --git a/guava/src/com/google/common/collect/MinMaxPriorityQueue.java b/guava/src/com/google/common/collect/MinMaxPriorityQueue.java
index fe3412d552ee..61a5336714d8 100644
--- a/guava/src/com/google/common/collect/MinMaxPriorityQueue.java
+++ b/guava/src/com/google/common/collect/MinMaxPriorityQueue.java
@@ -43,6 +43,7 @@
 import java.util.PriorityQueue;
 import java.util.Queue;
 import javax.annotation.CheckForNull;
+import org.checkerframework.checker.index.qual.NonNegative;
 import org.checkerframework.checker.nullness.qual.Nullable;
 import org.checkerframework.checker.nullness.qual.PolyNull;
 import org.checkerframework.checker.signedness.qual.PolySigned;
@@ -252,7 +253,7 @@ private MinMaxPriorityQueue(Builder<? super E> builder, int queueSize) {
   }
 
   @Override
-  public int size() {
+  public @NonNegative int size() {
     return size;
   }
 
diff --git a/guava/src/com/google/common/collect/Multimaps.java b/guava/src/com/google/common/collect/Multimaps.java
index 170acebc69eb..6bb6bdb7e357 100644
--- a/guava/src/com/google/common/collect/Multimaps.java
+++ b/guava/src/com/google/common/collect/Multimaps.java
@@ -1196,7 +1196,7 @@ public void remove() {
 
         @Pure
         @Override
-        public int size() {
+        public @NonNegative int size() {
           return map.containsKey(key) ? 1 : 0;
         }
       };
@@ -1786,7 +1786,7 @@ int distinctElements() {
     }
 
     @Override
-    public int size() {
+    public @NonNegative int size() {
       return multimap.size();
     }
 
@@ -1854,7 +1854,7 @@ abstract static class Entries<K extends @Nullable Object, V extends @Nullable Ob
     abstract Multimap<K, V> multimap();
 
     @Override
-    public int size() {
+    public @NonNegative int size() {
       return multimap().size();
     }
 
@@ -1892,7 +1892,7 @@ static final class AsMap<K extends @Nullable Object, V extends @Nullable Object>
     }
 
     @Override
-    public int size() {
+    public @NonNegative int size() {
       return multimap.keySet().size();
     }
 
diff --git a/guava/src/com/google/common/collect/Multiset.java b/guava/src/com/google/common/collect/Multiset.java
index 501428797803..5739414ff974 100644
--- a/guava/src/com/google/common/collect/Multiset.java
+++ b/guava/src/com/google/common/collect/Multiset.java
@@ -31,6 +31,7 @@
 import java.util.function.Consumer;
 import java.util.function.ObjIntConsumer;
 import javax.annotation.CheckForNull;
+import org.checkerframework.checker.index.qual.NonNegative;
 import org.checkerframework.checker.nullness.qual.Nullable;
 import org.checkerframework.checker.signedness.qual.UnknownSignedness;
 import org.checkerframework.dataflow.qual.Pure;
@@ -102,7 +103,7 @@ public interface Multiset<E extends @Nullable Object> extends Collection<E> {
    * multiset, which is given by {@code entrySet().size()}.
    */
   @Override
-  int size();
+  @NonNegative int size();
 
   /**
    * Returns the number of occurrences of an element in this multiset (the <i>count</i> of the
diff --git a/guava/src/com/google/common/collect/Multisets.java b/guava/src/com/google/common/collect/Multisets.java
index 5a4fddfa5287..3d656cb9d0dd 100644
--- a/guava/src/com/google/common/collect/Multisets.java
+++ b/guava/src/com/google/common/collect/Multisets.java
@@ -568,7 +568,7 @@ public boolean isEmpty() {
       }
 
       @Override
-      public int size() {
+      public @NonNegative int size() {
         return IntMath.saturatedAdd(multiset1.size(), multiset2.size());
       }
 
@@ -1029,7 +1029,7 @@ public boolean remove(@CheckForNull @UnknownSignedness Object o) {
     }
 
     @Override
-    public int size() {
+    public @NonNegative int size() {
       return multiset().entrySet().size();
     }
   }
@@ -1198,7 +1198,7 @@ public int compare(Entry<?> entry1, Entry<?> entry2) {
   private abstract static class ViewMultiset<E extends @Nullable Object>
       extends AbstractMultiset<E> {
     @Override
-    public int size() {
+    public @NonNegative int size() {
       return linearTimeSizeImpl(this);
     }
 
diff --git a/guava/src/com/google/common/collect/RegularContiguousSet.java b/guava/src/com/google/common/collect/RegularContiguousSet.java
index 787606eb1f81..a9db661d6ffa 100644
--- a/guava/src/com/google/common/collect/RegularContiguousSet.java
+++ b/guava/src/com/google/common/collect/RegularContiguousSet.java
@@ -25,6 +25,7 @@
 import java.io.Serializable;
 import java.util.Collection;
 import javax.annotation.CheckForNull;
+import org.checkerframework.checker.index.qual.NonNegative;
 
 /**
  * An implementation of {@link ContiguousSet} that contains one or more elements.
@@ -147,7 +148,7 @@ public C get(int i) {
   }
 
   @Override
-  public int size() {
+  public @NonNegative int size() {
     long distance = domain.distance(first(), last());
     return (distance >= Integer.MAX_VALUE) ? Integer.MAX_VALUE : (int) distance + 1;
   }
diff --git a/guava/src/com/google/common/collect/RegularImmutableBiMap.java b/guava/src/com/google/common/collect/RegularImmutableBiMap.java
index f4928f3af2d5..d07e079d6e90 100644
--- a/guava/src/com/google/common/collect/RegularImmutableBiMap.java
+++ b/guava/src/com/google/common/collect/RegularImmutableBiMap.java
@@ -34,6 +34,7 @@
 import java.util.function.BiConsumer;
 import java.util.function.Consumer;
 import javax.annotation.CheckForNull;
+import org.checkerframework.checker.index.qual.NonNegative;
 import org.checkerframework.checker.nullness.qual.Nullable;
 import org.checkerframework.checker.signedness.qual.UnknownSignedness;
 import org.checkerframework.framework.qual.AnnotatedFor;
@@ -186,7 +187,7 @@ boolean isPartialView() {
   }
 
   @Override
-  public int size() {
+  public @NonNegative int size() {
     return entries.length;
   }
 
@@ -204,7 +205,7 @@ public ImmutableBiMap<V, K> inverse() {
   private final class Inverse extends ImmutableBiMap<V, K> {
 
     @Override
-    public int size() {
+    public @NonNegative int size() {
       return inverse().size();
     }
 
diff --git a/guava/src/com/google/common/collect/RegularImmutableList.java b/guava/src/com/google/common/collect/RegularImmutableList.java
index e1dc4a467306..e35b40c42f3c 100644
--- a/guava/src/com/google/common/collect/RegularImmutableList.java
+++ b/guava/src/com/google/common/collect/RegularImmutableList.java
@@ -20,6 +20,7 @@
 import com.google.common.annotations.VisibleForTesting;
 import java.util.Spliterator;
 import java.util.Spliterators;
+import org.checkerframework.checker.index.qual.NonNegative;
 import org.checkerframework.checker.nullness.qual.Nullable;
 import org.checkerframework.checker.signedness.qual.UnknownSignedness;
 import org.checkerframework.dataflow.qual.Pure;
@@ -46,7 +47,7 @@ class RegularImmutableList<E> extends ImmutableList<E> {
 
   @Pure
   @Override
-  public int size() {
+  public @NonNegative int size() {
     return array.length;
   }
 
diff --git a/guava/src/com/google/common/collect/RegularImmutableMap.java b/guava/src/com/google/common/collect/RegularImmutableMap.java
index a55923f518d6..6ca142d36ee1 100644
--- a/guava/src/com/google/common/collect/RegularImmutableMap.java
+++ b/guava/src/com/google/common/collect/RegularImmutableMap.java
@@ -32,6 +32,7 @@
 import java.util.IdentityHashMap;
 import java.util.function.BiConsumer;
 import javax.annotation.CheckForNull;
+import org.checkerframework.checker.index.qual.NonNegative;
 import org.checkerframework.checker.nullness.qual.KeyFor;
 import org.checkerframework.checker.nullness.qual.Nullable;
 import org.checkerframework.checker.signedness.qual.UnknownSignedness;
@@ -302,7 +303,7 @@ public void forEach(BiConsumer<? super K, ? super V> action) {
   }
 
   @Override
-  public int size() {
+  public @NonNegative int size() {
     return entries.length;
   }
 
@@ -345,7 +346,7 @@ boolean isPartialView() {
     }
 
     @Override
-    public int size() {
+    public @NonNegative int size() {
       return map.size();
     }
 
@@ -386,7 +387,7 @@ public V get(int index) {
     }
 
     @Override
-    public int size() {
+    public @NonNegative int size() {
       return map.size();
     }
 
diff --git a/guava/src/com/google/common/collect/RegularImmutableMultiset.java b/guava/src/com/google/common/collect/RegularImmutableMultiset.java
index 4e0cecdc13fd..1169e124de4b 100644
--- a/guava/src/com/google/common/collect/RegularImmutableMultiset.java
+++ b/guava/src/com/google/common/collect/RegularImmutableMultiset.java
@@ -26,6 +26,7 @@
 import java.util.Collection;
 import javax.annotation.CheckForNull;
 import org.checkerframework.checker.index.qual.NonNegative;
+import org.checkerframework.checker.index.qual.NonNegative;
 import org.checkerframework.checker.nullness.qual.Nullable;
 import org.checkerframework.checker.signedness.qual.UnknownSignedness;
 
@@ -177,7 +178,7 @@ boolean isPartialView() {
   }
 
   @Override
-  public int size() {
+  public @NonNegative int size() {
     return size;
   }
 
diff --git a/guava/src/com/google/common/collect/RegularImmutableSet.java b/guava/src/com/google/common/collect/RegularImmutableSet.java
index b0d970f66766..7b79268e4f5a 100644
--- a/guava/src/com/google/common/collect/RegularImmutableSet.java
+++ b/guava/src/com/google/common/collect/RegularImmutableSet.java
@@ -21,6 +21,7 @@
 import java.util.Spliterator;
 import java.util.Spliterators;
 import javax.annotation.CheckForNull;
+import org.checkerframework.checker.index.qual.NonNegative;
 import org.checkerframework.checker.nullness.qual.Nullable;
 import org.checkerframework.dataflow.qual.Pure;
 import org.checkerframework.framework.qual.AnnotatedFor;
@@ -72,7 +73,7 @@ public boolean contains(@CheckForNull Object target) {
   }
 
   @Override
-  public int size() {
+  public @NonNegative int size() {
     return elements.length;
   }
 
diff --git a/guava/src/com/google/common/collect/RegularImmutableSortedMultiset.java b/guava/src/com/google/common/collect/RegularImmutableSortedMultiset.java
index 94499933cb39..cdb7e7151aa2 100644
--- a/guava/src/com/google/common/collect/RegularImmutableSortedMultiset.java
+++ b/guava/src/com/google/common/collect/RegularImmutableSortedMultiset.java
@@ -25,6 +25,7 @@
 import java.util.function.ObjIntConsumer;
 import javax.annotation.CheckForNull;
 import org.checkerframework.checker.index.qual.NonNegative;
+import org.checkerframework.checker.index.qual.NonNegative;
 import org.checkerframework.checker.signedness.qual.UnknownSignedness;
 
 /**
@@ -97,7 +98,7 @@ public Entry<E> lastEntry() {
   }
 
   @Override
-  public int size() {
+  public @NonNegative int size() {
     long size = cumulativeCounts[offset + length] - cumulativeCounts[offset];
     return Ints.saturatedCast(size);
   }
diff --git a/guava/src/com/google/common/collect/RegularImmutableSortedSet.java b/guava/src/com/google/common/collect/RegularImmutableSortedSet.java
index fce26bcc1d5c..7ac7d0fed4ed 100644
--- a/guava/src/com/google/common/collect/RegularImmutableSortedSet.java
+++ b/guava/src/com/google/common/collect/RegularImmutableSortedSet.java
@@ -29,6 +29,7 @@
 import java.util.Spliterator;
 import java.util.function.Consumer;
 import javax.annotation.CheckForNull;
+import org.checkerframework.checker.index.qual.NonNegative;
 import org.checkerframework.checker.nullness.qual.Nullable;
 import org.checkerframework.checker.signedness.qual.UnknownSignedness;
 import org.checkerframework.dataflow.qual.Pure;
@@ -96,7 +97,7 @@ public void forEach(Consumer<? super E> action) {
   }
 
   @Override
-  public int size() {
+  public @NonNegative int size() {
     return elements.size();
   }
 
diff --git a/guava/src/com/google/common/collect/RegularImmutableTable.java b/guava/src/com/google/common/collect/RegularImmutableTable.java
index b7ec63f04596..0b71914ead32 100644
--- a/guava/src/com/google/common/collect/RegularImmutableTable.java
+++ b/guava/src/com/google/common/collect/RegularImmutableTable.java
@@ -26,6 +26,7 @@
 import java.util.Set;
 import javax.annotation.CheckForNull;
 
+import org.checkerframework.checker.index.qual.NonNegative;
 import org.checkerframework.checker.signedness.qual.UnknownSignedness;
 
 /**
@@ -48,7 +49,7 @@ final ImmutableSet<Cell<R, C, V>> createCellSet() {
   @WeakOuter
   private final class CellSet extends IndexedImmutableSet<Cell<R, C, V>> {
     @Override
-    public int size() {
+    public @NonNegative int size() {
       return RegularImmutableTable.this.size();
     }
 
@@ -83,7 +84,7 @@ final ImmutableCollection<V> createValues() {
   @WeakOuter
   private final class Values extends ImmutableList<V> {
     @Override
-    public int size() {
+    public @NonNegative int size() {
       return RegularImmutableTable.this.size();
     }
 
diff --git a/guava/src/com/google/common/collect/Sets.java b/guava/src/com/google/common/collect/Sets.java
index bb4bea7a1ed8..9b771f387586 100644
--- a/guava/src/com/google/common/collect/Sets.java
+++ b/guava/src/com/google/common/collect/Sets.java
@@ -53,6 +53,7 @@
 import java.util.stream.Collector;
 import java.util.stream.Stream;
 import javax.annotation.CheckForNull;
+import org.checkerframework.checker.index.qual.NonNegative;
 import org.checkerframework.checker.nullness.qual.Nullable;
 import org.checkerframework.checker.nullness.qual.PolyNull;
 import org.checkerframework.checker.signedness.qual.PolySigned;
@@ -716,7 +717,7 @@ public final void clear() {
     return new SetView<E>() {
       @Pure
       @Override
-      public int size() {
+      public @NonNegative int size() {
         int size = set1.size();
         for (E e : set2) {
           if (!set1.contains(e)) {
@@ -848,7 +849,7 @@ public Stream<E> parallelStream() {
       }
 
       @Override
-      public int size() {
+      public @NonNegative int size() {
         int size = 0;
         for (E e : set1) {
           if (set2.contains(e)) {
@@ -921,7 +922,7 @@ public Stream<E> parallelStream() {
       }
 
       @Override
-      public int size() {
+      public @NonNegative int size() {
         int size = 0;
         for (E e : set1) {
           if (!set2.contains(e)) {
@@ -986,7 +987,7 @@ public E computeNext() {
       }
 
       @Override
-      public int size() {
+      public @NonNegative int size() {
         int size = 0;
         for (E e : set1) {
           if (!set2.contains(e)) {
@@ -1415,7 +1416,7 @@ static <E> Set<List<E>> create(List<? extends Set<? extends E>> sets) {
       ImmutableList<List<E>> listAxes =
           new ImmutableList<List<E>>() {
             @Override
-            public int size() {
+            public @NonNegative int size() {
               return axes.size();
             }
 
@@ -1557,7 +1558,7 @@ public E next() {
     }
 
     @Override
-    public int size() {
+    public @NonNegative int size() {
       return Integer.bitCount(mask);
     }
 
@@ -1578,7 +1579,7 @@ private static final class PowerSet<E> extends AbstractSet<Set<E>> {
     }
 
     @Override
-    public int size() {
+    public @NonNegative int size() {
       return 1 << inputSet.size();
     }
 
@@ -1736,7 +1737,7 @@ protected E computeNext() {
               }
 
               @Override
-              public int size() {
+              public @NonNegative int size() {
                 return size;
               }
             };
@@ -1745,7 +1746,7 @@ public int size() {
       }
 
       @Override
-      public int size() {
+      public @NonNegative int size() {
         return IntMath.binomial(index.size(), size);
       }
 
diff --git a/guava/src/com/google/common/collect/SingletonImmutableBiMap.java b/guava/src/com/google/common/collect/SingletonImmutableBiMap.java
index 1e76ef710735..fdc6d3d9bbdd 100644
--- a/guava/src/com/google/common/collect/SingletonImmutableBiMap.java
+++ b/guava/src/com/google/common/collect/SingletonImmutableBiMap.java
@@ -24,6 +24,7 @@
 import com.google.j2objc.annotations.RetainedWith;
 import java.util.function.BiConsumer;
 import javax.annotation.CheckForNull;
+import org.checkerframework.checker.index.qual.NonNegative;
 import org.checkerframework.checker.signedness.qual.UnknownSignedness;
 
 /**
@@ -60,7 +61,7 @@ public V get(@CheckForNull @UnknownSignedness Object key) {
   }
 
   @Override
-  public int size() {
+  public @NonNegative int size() {
     return 1;
   }
 
diff --git a/guava/src/com/google/common/collect/SingletonImmutableList.java b/guava/src/com/google/common/collect/SingletonImmutableList.java
index c0d388e821d9..3a840b5aad7e 100644
--- a/guava/src/com/google/common/collect/SingletonImmutableList.java
+++ b/guava/src/com/google/common/collect/SingletonImmutableList.java
@@ -22,6 +22,7 @@
 import com.google.common.base.Preconditions;
 import java.util.Collections;
 import java.util.Spliterator;
+import org.checkerframework.checker.index.qual.NonNegative;
 import org.checkerframework.checker.nullness.qual.Nullable;
 import org.checkerframework.dataflow.qual.Pure;
 import org.checkerframework.dataflow.qual.SideEffectFree;
@@ -62,7 +63,7 @@ public Spliterator<E> spliterator() {
   }
 
   @Override
-  public int size() {
+  public @NonNegative int size() {
     return 1;
   }
 
diff --git a/guava/src/com/google/common/collect/SingletonImmutableSet.java b/guava/src/com/google/common/collect/SingletonImmutableSet.java
index cbfcee3560f7..2de73aa7101e 100644
--- a/guava/src/com/google/common/collect/SingletonImmutableSet.java
+++ b/guava/src/com/google/common/collect/SingletonImmutableSet.java
@@ -20,6 +20,7 @@
 import com.google.common.base.Preconditions;
 import com.google.errorprone.annotations.concurrent.LazyInit;
 import javax.annotation.CheckForNull;
+import org.checkerframework.checker.index.qual.NonNegative;
 import org.checkerframework.checker.nullness.qual.Nullable;
 import org.checkerframework.dataflow.qual.Pure;
 import org.checkerframework.framework.qual.AnnotatedFor;
@@ -47,7 +48,7 @@ final class SingletonImmutableSet<E> extends ImmutableSet<E> {
 
   @Pure
   @Override
-  public int size() {
+  public @NonNegative int size() {
     return 1;
   }
 
diff --git a/guava/src/com/google/common/collect/StandardTable.java b/guava/src/com/google/common/collect/StandardTable.java
index eafda57f98bd..175b92bdc385 100644
--- a/guava/src/com/google/common/collect/StandardTable.java
+++ b/guava/src/com/google/common/collect/StandardTable.java
@@ -45,6 +45,7 @@
 import java.util.Spliterator;
 import java.util.Spliterators;
 import javax.annotation.CheckForNull;
+import org.checkerframework.checker.index.qual.NonNegative;
 import org.checkerframework.checker.nullness.qual.KeyFor;
 import org.checkerframework.checker.signedness.qual.UnknownSignedness;
 
@@ -390,7 +391,7 @@ public void clear() {
     }
 
     @Override
-    public int size() {
+    public @NonNegative int size() {
       updateBackingRowMapField();
       return (backingRowMap == null) ? 0 : backingRowMap.size();
     }
@@ -524,7 +525,7 @@ public Iterator<Entry<R, V>> iterator() {
       }
 
       @Override
-      public int size() {
+      public @NonNegative int size() {
         int size = 0;
         for (Map<C, V> map : backingMap.values()) {
           if (map.containsKey(columnKey)) {
@@ -700,7 +701,7 @@ public Iterator<C> iterator() {
     }
 
     @Override
-    public int size() {
+    public @NonNegative int size() {
       return Iterators.size(iterator());
     }
 
@@ -861,7 +862,7 @@ public Map<C, V> apply(R rowKey) {
       }
 
       @Override
-      public int size() {
+      public @NonNegative int size() {
         return backingMap.size();
       }
 
@@ -950,7 +951,7 @@ public Map<R, V> apply(C columnKey) {
       }
 
       @Override
-      public int size() {
+      public @NonNegative int size() {
         return columnKeySet().size();
       }
 
diff --git a/guava/src/com/google/common/collect/Synchronized.java b/guava/src/com/google/common/collect/Synchronized.java
index ac28cb325f27..c3a8b4a2b141 100644
--- a/guava/src/com/google/common/collect/Synchronized.java
+++ b/guava/src/com/google/common/collect/Synchronized.java
@@ -250,7 +250,7 @@ public boolean removeIf(Predicate<? super E> filter) {
     }
 
     @Override
-    public int size() {
+    public @NonNegative int size() {
       synchronized (mutex) {
         return delegate().size();
       }
@@ -1292,7 +1292,7 @@ public boolean remove(@CheckForNull @UnknownSignedness Object key, @CheckForNull
     }
 
     @Override
-    public int size() {
+    public @NonNegative int size() {
       synchronized (mutex) {
         return delegate().size();
       }
diff --git a/guava/src/com/google/common/collect/TransformedListIterator.java b/guava/src/com/google/common/collect/TransformedListIterator.java
index 66b42e4c6048..094f2ab1221a 100644
--- a/guava/src/com/google/common/collect/TransformedListIterator.java
+++ b/guava/src/com/google/common/collect/TransformedListIterator.java
@@ -19,6 +19,7 @@
 import com.google.common.annotations.GwtCompatible;
 import com.google.common.base.Function;
 import java.util.ListIterator;
+import org.checkerframework.checker.index.qual.NonNegative;
 import org.checkerframework.checker.nullness.qual.Nullable;
 
 /**
@@ -51,12 +52,12 @@ public final T previous() {
   }
 
   @Override
-  public final int nextIndex() {
+  public final @NonNegative int nextIndex() {
     return backingIterator().nextIndex();
   }
 
   @Override
-  public final int previousIndex() {
+  public final @NonNegative int previousIndex() {
     return backingIterator().previousIndex();
   }
 
diff --git a/guava/src/com/google/common/collect/TreeMultiset.java b/guava/src/com/google/common/collect/TreeMultiset.java
index 62815d67da69..3e2561d7d564 100644
--- a/guava/src/com/google/common/collect/TreeMultiset.java
+++ b/guava/src/com/google/common/collect/TreeMultiset.java
@@ -233,7 +233,7 @@ private long aggregateAboveRange(Aggregate aggr, @CheckForNull AvlNode<E> node)
 
   @Pure
   @Override
-  public int size() {
+  public @NonNegative int size() {
     return Ints.saturatedCast(aggregateForEntries(Aggregate.SIZE));
   }
 
diff --git a/guava/src/com/google/common/collect/TreeRangeMap.java b/guava/src/com/google/common/collect/TreeRangeMap.java
index 01922c11bff0..f4c0ccf459af 100644
--- a/guava/src/com/google/common/collect/TreeRangeMap.java
+++ b/guava/src/com/google/common/collect/TreeRangeMap.java
@@ -40,6 +40,7 @@
 import java.util.Set;
 import java.util.function.BiFunction;
 import javax.annotation.CheckForNull;
+import org.checkerframework.checker.index.qual.NonNegative;
 import org.checkerframework.checker.nullness.qual.KeyFor;
 import org.checkerframework.checker.nullness.qual.Nullable;
 import org.checkerframework.checker.signedness.qual.UnknownSignedness;
@@ -360,7 +361,7 @@ public V get(@CheckForNull @UnknownSignedness Object key) {
     }
 
     @Override
-    public int size() {
+    public @NonNegative int size() {
       return entriesByLowerBound.size();
     }
 
@@ -748,7 +749,7 @@ public boolean retainAll(Collection<?> c) {
           }
 
           @Override
-          public int size() {
+          public @NonNegative int size() {
             return Iterators.size(iterator());
           }
 
diff --git a/guava/src/com/google/common/collect/TreeRangeSet.java b/guava/src/com/google/common/collect/TreeRangeSet.java
index 7ba71139eb96..308992f804ba 100644
--- a/guava/src/com/google/common/collect/TreeRangeSet.java
+++ b/guava/src/com/google/common/collect/TreeRangeSet.java
@@ -31,6 +31,7 @@
 import java.util.Set;
 import java.util.TreeMap;
 import javax.annotation.CheckForNull;
+import org.checkerframework.checker.index.qual.NonNegative;
 
 /**
  * An implementation of {@link RangeSet} backed by a {@link TreeMap}.
@@ -436,7 +437,7 @@ protected Entry<Cut<C>, Range<C>> computeNext() {
     }
 
     @Override
-    public int size() {
+    public @NonNegative int size() {
       if (upperBoundWindow.equals(Range.all())) {
         return rangesByLowerBound.size();
       }
@@ -627,7 +628,7 @@ protected Entry<Cut<C>, Range<C>> computeNext() {
     }
 
     @Override
-    public int size() {
+    public @NonNegative int size() {
       return Iterators.size(entryIterator());
     }
 
@@ -860,7 +861,7 @@ protected Entry<Cut<C>, Range<C>> computeNext() {
     }
 
     @Override
-    public int size() {
+    public @NonNegative int size() {
       return Iterators.size(entryIterator());
     }
   }
diff --git a/guava/src/com/google/common/graph/AbstractBaseGraph.java b/guava/src/com/google/common/graph/AbstractBaseGraph.java
index 63ddcec1bde9..3cecb5dc6fbe 100644
--- a/guava/src/com/google/common/graph/AbstractBaseGraph.java
+++ b/guava/src/com/google/common/graph/AbstractBaseGraph.java
@@ -31,6 +31,7 @@
 import java.util.Set;
 import javax.annotation.CheckForNull;
 
+import org.checkerframework.checker.index.qual.NonNegative;
 import org.checkerframework.checker.signedness.qual.UnknownSignedness;
 
 /**
@@ -73,7 +74,7 @@ public UnmodifiableIterator<EndpointPair<N>> iterator() {
       }
 
       @Override
-      public int size() {
+      public @NonNegative int size() {
         return Ints.saturatedCast(edgeCount());
       }
 
diff --git a/guava/src/com/google/common/graph/AbstractDirectedNetworkConnections.java b/guava/src/com/google/common/graph/AbstractDirectedNetworkConnections.java
index 4b221bfbc58f..8d2d1450cea8 100644
--- a/guava/src/com/google/common/graph/AbstractDirectedNetworkConnections.java
+++ b/guava/src/com/google/common/graph/AbstractDirectedNetworkConnections.java
@@ -33,6 +33,7 @@
 import java.util.Set;
 import javax.annotation.CheckForNull;
 
+import org.checkerframework.checker.index.qual.NonNegative;
 import org.checkerframework.checker.signedness.qual.UnknownSignedness;
 
 /**
@@ -77,7 +78,7 @@ public UnmodifiableIterator<E> iterator() {
       }
 
       @Override
-      public int size() {
+      public @NonNegative int size() {
         return IntMath.saturatedAdd(inEdgeMap.size(), outEdgeMap.size() - selfLoopCount);
       }
 
diff --git a/guava/src/com/google/common/graph/AbstractNetwork.java b/guava/src/com/google/common/graph/AbstractNetwork.java
index 363fb4393dbc..ab002bfd0e19 100644
--- a/guava/src/com/google/common/graph/AbstractNetwork.java
+++ b/guava/src/com/google/common/graph/AbstractNetwork.java
@@ -37,6 +37,7 @@
 import java.util.Set;
 import javax.annotation.CheckForNull;
 
+import org.checkerframework.checker.index.qual.NonNegative;
 import org.checkerframework.checker.signedness.qual.UnknownSignedness;
 
 /**
@@ -84,7 +85,7 @@ public EndpointPair<N> apply(E edge) {
           }
 
           @Override
-          public int size() {
+          public @NonNegative int size() {
             return AbstractNetwork.this.edges().size();
           }
 
diff --git a/guava/src/com/google/common/graph/DirectedGraphConnections.java b/guava/src/com/google/common/graph/DirectedGraphConnections.java
index dc6021c5c726..8d72a786f859 100644
--- a/guava/src/com/google/common/graph/DirectedGraphConnections.java
+++ b/guava/src/com/google/common/graph/DirectedGraphConnections.java
@@ -42,6 +42,7 @@
 import java.util.concurrent.atomic.AtomicBoolean;
 import javax.annotation.CheckForNull;
 
+import org.checkerframework.checker.index.qual.NonNegative;
 import org.checkerframework.checker.signedness.qual.UnknownSignedness;
 
 /**
@@ -260,7 +261,7 @@ protected N computeNext() {
         }
 
         @Override
-        public int size() {
+        public @NonNegative int size() {
           return adjacentNodeValues.size();
         }
 
@@ -311,7 +312,7 @@ protected N computeNext() {
       }
 
       @Override
-      public int size() {
+      public @NonNegative int size() {
         return predecessorCount;
       }
 
@@ -361,7 +362,7 @@ protected N computeNext() {
       }
 
       @Override
-      public int size() {
+      public @NonNegative int size() {
         return successorCount;
       }
 
diff --git a/guava/src/com/google/common/graph/DirectedMultiNetworkConnections.java b/guava/src/com/google/common/graph/DirectedMultiNetworkConnections.java
index bd0e546f26e3..3f2195fca519 100644
--- a/guava/src/com/google/common/graph/DirectedMultiNetworkConnections.java
+++ b/guava/src/com/google/common/graph/DirectedMultiNetworkConnections.java
@@ -31,6 +31,7 @@
 import java.util.Map;
 import java.util.Set;
 import javax.annotation.CheckForNull;
+import org.checkerframework.checker.index.qual.NonNegative;
 
 /**
  * An implementation of {@link NetworkConnections} for directed networks with parallel edges.
@@ -96,7 +97,7 @@ private Multiset<N> successorsMultiset() {
   public Set<E> edgesConnecting(N node) {
     return new MultiEdgesConnecting<E>(outEdgeMap, node) {
       @Override
-      public int size() {
+      public @NonNegative int size() {
         return successorsMultiset().count(node);
       }
     };
diff --git a/guava/src/com/google/common/graph/EdgesConnecting.java b/guava/src/com/google/common/graph/EdgesConnecting.java
index 4c7aa9fc5dcf..c2f4055b5b90 100644
--- a/guava/src/com/google/common/graph/EdgesConnecting.java
+++ b/guava/src/com/google/common/graph/EdgesConnecting.java
@@ -25,6 +25,7 @@
 import java.util.Map;
 import javax.annotation.CheckForNull;
 
+import org.checkerframework.checker.index.qual.NonNegative;
 import org.checkerframework.checker.signedness.qual.UnknownSignedness;
 
 /**
@@ -56,7 +57,7 @@ public UnmodifiableIterator<E> iterator() {
   }
 
   @Override
-  public int size() {
+  public @NonNegative int size() {
     return getConnectingEdge() == null ? 0 : 1;
   }
 
diff --git a/guava/src/com/google/common/graph/IncidentEdgeSet.java b/guava/src/com/google/common/graph/IncidentEdgeSet.java
index e46cbc5c3ce1..793996e70846 100644
--- a/guava/src/com/google/common/graph/IncidentEdgeSet.java
+++ b/guava/src/com/google/common/graph/IncidentEdgeSet.java
@@ -20,6 +20,7 @@
 import java.util.Set;
 import javax.annotation.CheckForNull;
 
+import org.checkerframework.checker.index.qual.NonNegative;
 import org.checkerframework.checker.signedness.qual.UnknownSignedness;
 
 /**
@@ -42,7 +43,7 @@ public boolean remove(@CheckForNull @UnknownSignedness Object o) {
   }
 
   @Override
-  public int size() {
+  public @NonNegative int size() {
     if (graph.isDirected()) {
       return graph.inDegree(node)
           + graph.outDegree(node)
diff --git a/guava/src/com/google/common/graph/MapIteratorCache.java b/guava/src/com/google/common/graph/MapIteratorCache.java
index d8ac2adc571b..4d9e67ad471c 100644
--- a/guava/src/com/google/common/graph/MapIteratorCache.java
+++ b/guava/src/com/google/common/graph/MapIteratorCache.java
@@ -27,6 +27,7 @@
 import java.util.Set;
 import javax.annotation.CheckForNull;
 
+import org.checkerframework.checker.index.qual.NonNegative;
 import org.checkerframework.checker.signedness.qual.UnknownSignedness;
 
 /**
@@ -128,7 +129,7 @@ public K next() {
       }
 
       @Override
-      public int size() {
+      public @NonNegative int size() {
         return backingMap.size();
       }
 
diff --git a/guava/src/com/google/common/graph/UndirectedMultiNetworkConnections.java b/guava/src/com/google/common/graph/UndirectedMultiNetworkConnections.java
index 6caac3b715dd..e151ed3ee580 100644
--- a/guava/src/com/google/common/graph/UndirectedMultiNetworkConnections.java
+++ b/guava/src/com/google/common/graph/UndirectedMultiNetworkConnections.java
@@ -31,6 +31,7 @@
 import java.util.Map;
 import java.util.Set;
 import javax.annotation.CheckForNull;
+import org.checkerframework.checker.index.qual.NonNegative;
 
 /**
  * An implementation of {@link NetworkConnections} for undirected networks with parallel edges.
@@ -76,7 +77,7 @@ private Multiset<N> adjacentNodesMultiset() {
   public Set<E> edgesConnecting(N node) {
     return new MultiEdgesConnecting<E>(incidentEdgeMap, node) {
       @Override
-      public int size() {
+      public @NonNegative int size() {
         return adjacentNodesMultiset().count(node);
       }
     };
diff --git a/guava/src/com/google/common/hash/AbstractNonStreamingHashFunction.java b/guava/src/com/google/common/hash/AbstractNonStreamingHashFunction.java
index 8f9e3db01012..19a44a3bb11b 100644
--- a/guava/src/com/google/common/hash/AbstractNonStreamingHashFunction.java
+++ b/guava/src/com/google/common/hash/AbstractNonStreamingHashFunction.java
@@ -84,7 +84,7 @@ public HashCode hashString(@MinLen(1) CharSequence input, Charset charset) {
   }
 
   @Override
-  public abstract HashCode hashBytes(byte[] input, @NonNegative @LTLengthOf(value = "#1", offset = "#3 - 1") int off, @LTLengthOf(value = "#1", offset = "#2 - 1") int len);
+  public abstract HashCode hashBytes(byte[] input, @NonNegative @LTLengthOf(value = "#1", offset = "#3 - 1") int off, @NonNegative @LTLengthOf(value = "#1", offset = "#2 - 1") int len);
 
   @Override
   public HashCode hashBytes(ByteBuffer input) {
diff --git a/guava/src/com/google/common/hash/Fingerprint2011.java b/guava/src/com/google/common/hash/Fingerprint2011.java
index 1b01e0092418..89172f7d6694 100644
--- a/guava/src/com/google/common/hash/Fingerprint2011.java
+++ b/guava/src/com/google/common/hash/Fingerprint2011.java
@@ -8,6 +8,7 @@
 import static java.lang.Long.rotateRight;
 
 import com.google.common.annotations.VisibleForTesting;
+import org.checkerframework.checker.index.qual.NonNegative;
 
 /**
  * Implementation of Geoff Pike's fingerprint2011 hash function. See {@link Hashing#fingerprint2011}
@@ -45,7 +46,7 @@ public HashCode hashBytes(byte[] input, int off, int len) {
   }
 
   @Override
-  public int bits() {
+  public @NonNegative int bits() {
     return 64;
   }
 
diff --git a/guava/src/com/google/common/hash/Funnels.java b/guava/src/com/google/common/hash/Funnels.java
index e7020f1ebf0c..db88736065a0 100644
--- a/guava/src/com/google/common/hash/Funnels.java
+++ b/guava/src/com/google/common/hash/Funnels.java
@@ -16,10 +16,12 @@
 
 import com.google.common.annotations.Beta;
 import com.google.common.base.Preconditions;
+import java.io.IOException;
 import java.io.OutputStream;
 import java.io.Serializable;
 import java.nio.charset.Charset;
 import javax.annotation.CheckForNull;
+import org.checkerframework.checker.index.qual.IndexOrHigh;
 import org.checkerframework.checker.index.qual.LTLengthOf;
 import org.checkerframework.checker.index.qual.NonNegative;
 import org.checkerframework.checker.nullness.qual.Nullable;
@@ -268,7 +270,7 @@ public void write(byte @MinLen(1)[] bytes) {
     }
 
     @Override
-    public void write(@PolySigned byte[] bytes, @NonNegative @LTLengthOf(value = "#1", offset = "#3 - 1") int off, @NonNegative @LTLengthOf(value = "#1", offset = "#2 - 1") int len) {
+    public void write(@PolySigned byte[] bytes, @IndexOrHigh({"#1"}) int off, @LTLengthOf(value={"#1"}, offset={"#2 - 1"}) @NonNegative int len) throws IOException {
       sink.putBytes(bytes, off, len);
     }
 
diff --git a/guava/src/com/google/common/hash/HashingOutputStream.java b/guava/src/com/google/common/hash/HashingOutputStream.java
index 544abd9b04e8..b68261fff097 100644
--- a/guava/src/com/google/common/hash/HashingOutputStream.java
+++ b/guava/src/com/google/common/hash/HashingOutputStream.java
@@ -20,6 +20,7 @@
 import java.io.FilterOutputStream;
 import java.io.IOException;
 import java.io.OutputStream;
+import org.checkerframework.checker.index.qual.IndexOrHigh;
 import org.checkerframework.checker.index.qual.LTLengthOf;
 import org.checkerframework.checker.index.qual.NonNegative;
 import org.checkerframework.checker.signedness.qual.PolySigned;
@@ -56,10 +57,8 @@ public void write(@PolySigned int b) throws IOException {
     out.write(b);
   }
 
-  //@SuppressWarnings("override.param.invalid")//FilterOutputStream#write() should be annotated as
-  // void write(byte b[], @NonNegative @LTLengthOf(value = "#1",offset = "#3 - 1") int off, @NonNegative @LTLengthOf(value = "#1",offset = "#2 - 1") int len)
   @Override
-  public void write(@PolySigned byte[] bytes, @NonNegative @LTLengthOf(value = "#1",offset = "#3 - 1") int off, @NonNegative @LTLengthOf(value = "#1",offset = "#2 - 1") int len) throws IOException {
+  public void write(@PolySigned byte[] bytes, @IndexOrHigh({"#1"}) int off, @LTLengthOf(value={"#1"}, offset={"#2 - 1"}) @NonNegative int len) throws IOException {
     hasher.putBytes(bytes, off, len);
     out.write(bytes, off, len);
   }
diff --git a/guava/src/com/google/common/io/BaseEncoding.java b/guava/src/com/google/common/io/BaseEncoding.java
index c85b78a6349e..3e7d5450c90b 100644
--- a/guava/src/com/google/common/io/BaseEncoding.java
+++ b/guava/src/com/google/common/io/BaseEncoding.java
@@ -36,8 +36,10 @@
 import java.io.Writer;
 import java.util.Arrays;
 import javax.annotation.CheckForNull;
+import org.checkerframework.checker.index.qual.GTENegativeOne;
 import org.checkerframework.checker.index.qual.IndexFor;
 import org.checkerframework.checker.index.qual.IndexOrHigh;
+import org.checkerframework.checker.index.qual.LTEqLengthOf;
 import org.checkerframework.checker.index.qual.LTLengthOf;
 import org.checkerframework.checker.index.qual.NonNegative;
 import org.checkerframework.checker.nullness.qual.Nullable;
@@ -745,7 +747,7 @@ public InputStream decodingStream(Reader reader) {
         boolean hitPadding = false;
 
         @Override
-        public int read() throws IOException {
+        public @GTENegativeOne int read() throws IOException {
           while (true) {
             int readChar = reader.read();
             if (readChar == -1) {
@@ -779,7 +781,7 @@ public int read() throws IOException {
         }
 
         @Override
-        public int read(byte[] buf, int off, int len) throws IOException {
+        public @GTENegativeOne @LTEqLengthOf({"#1"}) int read(byte[] buf, @IndexOrHigh({"#1"}) int off, @LTLengthOf(value={"#1"}, offset={"#2 - 1"}) @NonNegative int len) throws IOException {
           // Overriding this to work around the fact that InputStream's default implementation of
           // this method will silently swallow exceptions thrown by the single-byte read() method
           // (other than on the first call to it), which in this case can cause invalid encoded
@@ -1005,7 +1007,7 @@ static Reader ignoringReader(Reader delegate, String toIgnore) {
     checkNotNull(toIgnore);
     return new Reader() {
       @Override
-      public int read() throws IOException {
+      public @GTENegativeOne int read() throws IOException {
         int readChar;
         do {
           readChar = delegate.read();
@@ -1014,7 +1016,7 @@ public int read() throws IOException {
       }
 
       @Override
-      public int read(char[] cbuf, int off, int len) throws IOException {
+      public @GTENegativeOne @LTEqLengthOf({"#1"}) int read(char[] cbuf, @IndexOrHigh({"#1"}) int off, @LTLengthOf(value={"#1"}, offset={"#2 - 1"}) @NonNegative int len) throws IOException {
         throw new UnsupportedOperationException();
       }
 
diff --git a/guava/src/com/google/common/net/PercentEscaper.java b/guava/src/com/google/common/net/PercentEscaper.java
index 92901473123c..2d06b5bb0a1a 100644
--- a/guava/src/com/google/common/net/PercentEscaper.java
+++ b/guava/src/com/google/common/net/PercentEscaper.java
@@ -19,6 +19,8 @@
 import com.google.common.annotations.GwtCompatible;
 import com.google.common.escape.UnicodeEscaper;
 import javax.annotation.CheckForNull;
+import org.checkerframework.checker.index.qual.IndexOrHigh;
+import org.checkerframework.checker.index.qual.NonNegative;
 
 /**
  * A {@code UnicodeEscaper} that escapes some set of Java characters using a UTF-8 based percent
@@ -125,7 +127,7 @@ private static boolean[] createSafeOctets(String safeChars) {
    * escaper from ~760ns to ~400ns as measured by {@link CharEscapersBenchmark}.
    */
   @Override
-  protected int nextEscapeIndex(CharSequence csq, int index, int end) {
+  protected @IndexOrHigh("#1") int nextEscapeIndex(CharSequence csq, @IndexOrHigh("#1") int index, @IndexOrHigh("#1") int end) {
     checkNotNull(csq);
     for (; index < end; index++) {
       char c = csq.charAt(index);

From 1b6f8cfc32c1bce4bdcb4880fa72c2b84568557b Mon Sep 17 00:00:00 2001
From: Mark Roberts <markro49@users.noreply.github.com>
Date: Thu, 8 Jun 2023 07:10:54 -0700
Subject: [PATCH 19/21] Add sign annotations

---
 guava/pom.xml                                 |  2 +-
 guava/src/com/google/common/base/Absent.java  |  3 ++-
 .../com/google/common/base/CaseFormat.java    |  3 ++-
 .../src/com/google/common/base/Converter.java |  7 ++++---
 guava/src/com/google/common/base/Enums.java   |  3 ++-
 .../com/google/common/base/Equivalence.java   |  5 +++--
 .../common/base/FunctionalEquivalence.java    |  3 ++-
 .../src/com/google/common/base/Functions.java | 13 +++++++------
 .../src/com/google/common/base/Optional.java  |  3 ++-
 .../common/base/PairwiseEquivalence.java      |  3 ++-
 .../com/google/common/base/Predicates.java    | 19 ++++++++++---------
 guava/src/com/google/common/base/Present.java |  3 ++-
 .../src/com/google/common/base/Suppliers.java |  5 +++--
 .../google/common/cache/CacheBuilderSpec.java |  3 ++-
 .../com/google/common/cache/CacheStats.java   |  3 ++-
 .../com/google/common/cache/LocalCache.java   |  2 +-
 .../collect/AbstractMapBasedMultimap.java     |  6 +++---
 .../common/collect/AbstractMapEntry.java      |  3 ++-
 .../common/collect/AbstractMultimap.java      |  4 ++--
 .../common/collect/AbstractMultiset.java      |  2 +-
 .../common/collect/AbstractRangeSet.java      |  3 ++-
 .../google/common/collect/AbstractTable.java  |  2 +-
 .../common/collect/ByFunctionOrdering.java    |  3 ++-
 .../google/common/collect/CartesianList.java  |  7 ++++---
 .../common/collect/ComparatorOrdering.java    |  3 ++-
 .../common/collect/CompoundOrdering.java      |  3 ++-
 .../collect/ConcurrentHashMultiset.java       |  6 +++---
 .../src/com/google/common/collect/Count.java  |  3 ++-
 guava/src/com/google/common/collect/Cut.java  | 11 ++++++-----
 .../common/collect/DenseImmutableTable.java   |  3 ++-
 .../collect/DescendingImmutableSortedSet.java |  3 ++-
 .../common/collect/DescendingMultiset.java    |  3 ++-
 .../common/collect/EmptyContiguousSet.java    |  7 ++++---
 .../google/common/collect/EnumMultiset.java   |  2 +-
 .../common/collect/ExplicitOrdering.java      |  3 ++-
 .../common/collect/FilteredEntryMultimap.java |  4 ++--
 .../collect/FilteredKeySetMultimap.java       |  5 +++--
 .../collect/FilteredMultimapValues.java       |  2 +-
 .../collect/ForwardingConcurrentMap.java      |  3 ++-
 .../google/common/collect/ForwardingList.java |  9 +++++----
 .../google/common/collect/ForwardingMap.java  |  2 +-
 .../common/collect/ForwardingMapEntry.java    |  3 ++-
 .../common/collect/ForwardingMultimap.java    |  2 +-
 .../common/collect/ForwardingMultiset.java    |  2 +-
 .../google/common/collect/ForwardingSet.java  |  2 +-
 .../common/collect/ForwardingTable.java       |  2 +-
 .../google/common/collect/GeneralRange.java   |  3 ++-
 .../com/google/common/collect/HashBiMap.java  |  4 ++--
 .../google/common/collect/HashMultiset.java   |  2 +-
 .../common/collect/ImmutableEnumMap.java      |  2 +-
 .../common/collect/ImmutableEnumSet.java      |  7 ++++---
 .../google/common/collect/ImmutableList.java  |  2 +-
 .../google/common/collect/ImmutableMap.java   |  4 ++--
 .../common/collect/ImmutableMapEntrySet.java  |  2 +-
 .../common/collect/ImmutableMapKeySet.java    |  3 ++-
 .../common/collect/ImmutableMapValues.java    |  3 ++-
 .../common/collect/ImmutableMultiset.java     |  4 ++--
 .../common/collect/ImmutableRangeMap.java     |  3 ++-
 .../common/collect/ImmutableRangeSet.java     |  3 ++-
 .../google/common/collect/ImmutableSet.java   |  2 +-
 .../common/collect/ImmutableSortedAsList.java |  7 ++++---
 .../common/collect/ImmutableSortedMap.java    |  4 ++--
 .../com/google/common/collect/Interners.java  |  3 ++-
 .../collect/JdkBackedImmutableBiMap.java      |  3 ++-
 .../common/collect/JdkBackedImmutableMap.java |  3 ++-
 .../common/collect/JdkBackedImmutableSet.java |  3 ++-
 .../collect/LexicographicalOrdering.java      |  3 ++-
 .../common/collect/LinkedHashMultimap.java    |  2 +-
 .../common/collect/LinkedListMultimap.java    |  2 +-
 .../google/common/collect/MapDifference.java  |  5 +++--
 .../common/collect/MapMakerInternalMap.java   |  2 +-
 guava/src/com/google/common/collect/Maps.java | 12 ++++++------
 .../com/google/common/collect/Multimap.java   |  2 +-
 .../com/google/common/collect/Multimaps.java  |  2 +-
 .../com/google/common/collect/Multiset.java   |  4 ++--
 .../com/google/common/collect/Multisets.java  |  2 +-
 .../common/collect/NullsFirstOrdering.java    |  3 ++-
 .../common/collect/NullsLastOrdering.java     |  3 ++-
 .../src/com/google/common/collect/Range.java  |  3 ++-
 .../com/google/common/collect/RangeMap.java   |  3 ++-
 .../com/google/common/collect/RangeSet.java   |  3 ++-
 .../common/collect/RegularContiguousSet.java  |  7 ++++---
 .../common/collect/RegularImmutableBiMap.java |  4 ++--
 .../common/collect/RegularImmutableList.java  |  2 +-
 .../collect/RegularImmutableMultiset.java     |  2 +-
 .../common/collect/RegularImmutableSet.java   |  5 +++--
 .../common/collect/ReverseOrdering.java       |  3 ++-
 guava/src/com/google/common/collect/Sets.java |  6 +++---
 .../collect/SingletonImmutableList.java       |  9 +++++----
 .../common/collect/SingletonImmutableSet.java |  7 ++++---
 .../google/common/collect/Synchronized.java   | 16 ++++++++--------
 .../src/com/google/common/collect/Table.java  |  4 ++--
 .../src/com/google/common/collect/Tables.java |  2 +-
 .../google/common/collect/TreeBasedTable.java |  3 ++-
 .../google/common/collect/TreeMultiset.java   |  2 +-
 .../google/common/collect/TreeRangeMap.java   |  4 ++--
 .../google/common/collect/TreeRangeSet.java   | 17 +++++++++--------
 .../google/common/eventbus/Subscriber.java    |  3 ++-
 .../common/eventbus/SubscriberRegistry.java   |  3 ++-
 .../google/common/graph/AbstractGraph.java    |  3 ++-
 .../google/common/graph/AbstractNetwork.java  |  2 +-
 .../common/graph/AbstractValueGraph.java      |  3 ++-
 .../graph/DirectedGraphConnections.java       |  6 +++---
 .../com/google/common/graph/ElementOrder.java |  3 ++-
 .../com/google/common/graph/EndpointPair.java |  7 ++++---
 guava/src/com/google/common/graph/Graph.java  |  3 ++-
 .../src/com/google/common/graph/Network.java  |  3 ++-
 .../com/google/common/graph/ValueGraph.java   |  3 ++-
 .../com/google/common/hash/BloomFilter.java   |  3 ++-
 .../common/hash/BloomFilterStrategies.java    |  3 ++-
 guava/src/com/google/common/hash/Funnels.java |  5 +++--
 .../src/com/google/common/hash/HashCode.java  |  3 ++-
 guava/src/com/google/common/hash/Hasher.java  |  3 ++-
 guava/src/com/google/common/hash/Hashing.java |  3 ++-
 .../common/hash/Murmur3_128HashFunction.java  |  3 ++-
 .../common/hash/Murmur3_32HashFunction.java   |  3 ++-
 .../google/common/hash/SipHashFunction.java   |  3 ++-
 .../com/google/common/io/BaseEncoding.java    |  5 +++--
 .../com/google/common/math/PairedStats.java   |  3 ++-
 guava/src/com/google/common/math/Stats.java   |  3 ++-
 .../com/google/common/net/HostAndPort.java    |  3 ++-
 .../com/google/common/net/HostSpecifier.java  |  3 ++-
 .../google/common/net/InternetDomainName.java |  3 ++-
 .../src/com/google/common/net/MediaType.java  |  3 ++-
 .../google/common/primitives/Booleans.java    |  2 +-
 .../com/google/common/primitives/Bytes.java   |  2 +-
 .../com/google/common/primitives/Chars.java   |  2 +-
 .../com/google/common/primitives/Doubles.java |  2 +-
 .../com/google/common/primitives/Floats.java  |  2 +-
 .../primitives/ImmutableDoubleArray.java      |  4 ++--
 .../common/primitives/ImmutableIntArray.java  |  4 ++--
 .../common/primitives/ImmutableLongArray.java |  4 ++--
 .../com/google/common/primitives/Ints.java    |  2 +-
 .../com/google/common/primitives/Longs.java   |  2 +-
 .../com/google/common/primitives/Shorts.java  |  2 +-
 .../common/primitives/UnsignedInteger.java    |  2 +-
 .../common/primitives/UnsignedLong.java       |  3 ++-
 .../reflect/AbstractInvocationHandler.java    |  3 ++-
 .../com/google/common/reflect/ClassPath.java  |  5 +++--
 .../com/google/common/reflect/Invokable.java  |  3 ++-
 .../com/google/common/reflect/Parameter.java  |  3 ++-
 .../google/common/reflect/TypeParameter.java  |  3 ++-
 .../google/common/reflect/TypeResolver.java   |  3 ++-
 .../com/google/common/reflect/TypeToken.java  |  3 ++-
 .../src/com/google/common/reflect/Types.java  |  9 +++++----
 pom.xml                                       |  2 +-
 146 files changed, 326 insertions(+), 236 deletions(-)

diff --git a/guava/pom.xml b/guava/pom.xml
index 7e495d6b2162..c017817f67ae 100644
--- a/guava/pom.xml
+++ b/guava/pom.xml
@@ -91,7 +91,7 @@
     <dependency>
       <groupId>org.checkerframework</groupId>
       <artifactId>checker</artifactId>
-      <version>3.34.0</version>
+      <version>3.35.0</version>
     </dependency>
   </dependencies>
   <build>
diff --git a/guava/src/com/google/common/base/Absent.java b/guava/src/com/google/common/base/Absent.java
index 65035ae8221b..b880c34cca9e 100644
--- a/guava/src/com/google/common/base/Absent.java
+++ b/guava/src/com/google/common/base/Absent.java
@@ -23,6 +23,7 @@
 import org.checkerframework.checker.nullness.qual.NonNull;
 import org.checkerframework.checker.nullness.qual.Nullable;
 import org.checkerframework.checker.nullness.qual.RequiresNonNull;
+import org.checkerframework.checker.signedness.qual.UnknownSignedness;
 import org.checkerframework.framework.qual.AnnotatedFor;
 
 /** Implementation of an {@link Optional} not containing a reference. */
@@ -89,7 +90,7 @@ public boolean equals(@CheckForNull Object object) {
   }
 
   @Override
-  public int hashCode() {
+  public int hashCode(@UnknownSignedness Absent<T> this) {
     return 0x79a31aac;
   }
 
diff --git a/guava/src/com/google/common/base/CaseFormat.java b/guava/src/com/google/common/base/CaseFormat.java
index 5957b92fb075..4a2bc40973cd 100644
--- a/guava/src/com/google/common/base/CaseFormat.java
+++ b/guava/src/com/google/common/base/CaseFormat.java
@@ -24,6 +24,7 @@
 import org.checkerframework.checker.index.qual.IndexOrHigh;
 import org.checkerframework.checker.index.qual.LTEqLengthOf;
 import org.checkerframework.checker.nullness.qual.Nullable;
+import org.checkerframework.checker.signedness.qual.UnknownSignedness;
 import org.checkerframework.common.value.qual.ArrayLen;
 
 /**
@@ -200,7 +201,7 @@ public boolean equals(@CheckForNull Object object) {
     }
 
     @Override
-    public int hashCode() {
+    public int hashCode(@UnknownSignedness StringConverter this) {
       return sourceFormat.hashCode() ^ targetFormat.hashCode();
     }
 
diff --git a/guava/src/com/google/common/base/Converter.java b/guava/src/com/google/common/base/Converter.java
index 6c16bcaf5934..bfac3a4eac7d 100644
--- a/guava/src/com/google/common/base/Converter.java
+++ b/guava/src/com/google/common/base/Converter.java
@@ -29,6 +29,7 @@
 import javax.annotation.CheckForNull;
 import org.checkerframework.checker.nullness.qual.Nullable;
 import org.checkerframework.checker.nullness.qual.PolyNull;
+import org.checkerframework.checker.signedness.qual.UnknownSignedness;
 
 /**
  * A function from {@code A} to {@code B} with an associated <i>reverse</i> function from {@code B}
@@ -369,7 +370,7 @@ public boolean equals(@CheckForNull Object object) {
     }
 
     @Override
-    public int hashCode() {
+    public int hashCode(@UnknownSignedness ReverseConverter<A, B> this) {
       return ~original.hashCode();
     }
 
@@ -446,7 +447,7 @@ public boolean equals(@CheckForNull Object object) {
     }
 
     @Override
-    public int hashCode() {
+    public int hashCode(@UnknownSignedness ConverterComposition<A, B, C> this) {
       return 31 * first.hashCode() + second.hashCode();
     }
 
@@ -572,7 +573,7 @@ public boolean equals(@CheckForNull Object object) {
     }
 
     @Override
-    public int hashCode() {
+    public int hashCode(@UnknownSignedness FunctionBasedConverter<A, B> this) {
       return forwardFunction.hashCode() * 31 + backwardFunction.hashCode();
     }
 
diff --git a/guava/src/com/google/common/base/Enums.java b/guava/src/com/google/common/base/Enums.java
index 16359ce5028d..319132a8bcaa 100644
--- a/guava/src/com/google/common/base/Enums.java
+++ b/guava/src/com/google/common/base/Enums.java
@@ -27,6 +27,7 @@
 import java.util.WeakHashMap;
 import javax.annotation.CheckForNull;
 import org.checkerframework.checker.nullness.qual.Nullable;
+import org.checkerframework.checker.signedness.qual.UnknownSignedness;
 import org.checkerframework.framework.qual.AnnotatedFor;
 
 /**
@@ -141,7 +142,7 @@ public boolean equals(@CheckForNull Object object) {
     }
 
     @Override
-    public int hashCode() {
+    public int hashCode(@UnknownSignedness StringConverter<T> this) {
       return enumClass.hashCode();
     }
 
diff --git a/guava/src/com/google/common/base/Equivalence.java b/guava/src/com/google/common/base/Equivalence.java
index 4e2e89886a2a..12228dfb2527 100644
--- a/guava/src/com/google/common/base/Equivalence.java
+++ b/guava/src/com/google/common/base/Equivalence.java
@@ -22,6 +22,7 @@
 import java.util.function.BiPredicate;
 import javax.annotation.CheckForNull;
 import org.checkerframework.checker.nullness.qual.Nullable;
+import org.checkerframework.checker.signedness.qual.UnknownSignedness;
 
 /**
  * A strategy for determining whether two instances are considered equivalent, and for computing
@@ -267,7 +268,7 @@ public boolean equals(@CheckForNull Object obj) {
 
     /** Returns the result of {@link Equivalence#hash(Object)} applied to the wrapped reference. */
     @Override
-    public int hashCode() {
+    public int hashCode(@UnknownSignedness Wrapper<T> this) {
       return equivalence.hash(reference);
     }
 
@@ -340,7 +341,7 @@ public boolean equals(@CheckForNull Object obj) {
     }
 
     @Override
-    public int hashCode() {
+    public int hashCode(@UnknownSignedness EquivalentToPredicate<T> this) {
       return Objects.hashCode(equivalence, target);
     }
 
diff --git a/guava/src/com/google/common/base/FunctionalEquivalence.java b/guava/src/com/google/common/base/FunctionalEquivalence.java
index 4383f4f36c1a..aabaddbb9ed0 100644
--- a/guava/src/com/google/common/base/FunctionalEquivalence.java
+++ b/guava/src/com/google/common/base/FunctionalEquivalence.java
@@ -21,6 +21,7 @@
 import java.io.Serializable;
 import javax.annotation.CheckForNull;
 import org.checkerframework.checker.nullness.qual.Nullable;
+import org.checkerframework.checker.signedness.qual.UnknownSignedness;
 
 /**
  * Equivalence applied on functional result.
@@ -67,7 +68,7 @@ public boolean equals(@CheckForNull Object obj) {
   }
 
   @Override
-  public int hashCode() {
+  public int hashCode(@UnknownSignedness FunctionalEquivalence<F, T> this) {
     return Objects.hashCode(function, resultEquivalence);
   }
 
diff --git a/guava/src/com/google/common/base/Functions.java b/guava/src/com/google/common/base/Functions.java
index 6797932b150a..9916c7ec11b5 100644
--- a/guava/src/com/google/common/base/Functions.java
+++ b/guava/src/com/google/common/base/Functions.java
@@ -23,6 +23,7 @@
 import java.util.Map;
 import javax.annotation.CheckForNull;
 import org.checkerframework.checker.nullness.qual.Nullable;
+import org.checkerframework.checker.signedness.qual.UnknownSignedness;
 import org.checkerframework.dataflow.qual.Pure;
 import org.checkerframework.framework.qual.AnnotatedFor;
 
@@ -173,7 +174,7 @@ public boolean equals(@CheckForNull Object o) {
 
     @Pure
     @Override
-    public int hashCode() {
+    public int hashCode(@UnknownSignedness FunctionForMapNoDefault<K, V> this) {
       return map.hashCode();
     }
 
@@ -218,7 +219,7 @@ public boolean equals(@CheckForNull Object o) {
 
     @Pure
     @Override
-    public int hashCode() {
+    public int hashCode(@UnknownSignedness ForMapWithDefault<K,V> this) {
       return Objects.hashCode(map, defaultValue);
     }
 
@@ -278,7 +279,7 @@ public boolean equals(@CheckForNull Object obj) {
 
     @Pure
     @Override
-    public int hashCode() {
+    public int hashCode(@UnknownSignedness FunctionComposition<A, B, C> this) {
       return f.hashCode() ^ g.hashCode();
     }
 
@@ -331,7 +332,7 @@ public boolean equals(@CheckForNull Object obj) {
 
     @Pure
     @Override
-    public int hashCode() {
+    public int hashCode(@UnknownSignedness PredicateFunction<T> this) {
       return predicate.hashCode();
     }
 
@@ -383,7 +384,7 @@ public boolean equals(@CheckForNull Object obj) {
 
     @Pure
     @Override
-    public int hashCode() {
+    public int hashCode(@UnknownSignedness ConstantFunction<E> this) {
       return (value == null) ? 0 : value.hashCode();
     }
 
@@ -434,7 +435,7 @@ public boolean equals(@CheckForNull Object obj) {
     }
 
     @Override
-    public int hashCode() {
+    public int hashCode(@UnknownSignedness SupplierFunction<F, T> this) {
       return supplier.hashCode();
     }
 
diff --git a/guava/src/com/google/common/base/Optional.java b/guava/src/com/google/common/base/Optional.java
index 0b9a5cf993c4..8700b4977b55 100644
--- a/guava/src/com/google/common/base/Optional.java
+++ b/guava/src/com/google/common/base/Optional.java
@@ -26,6 +26,7 @@
 import org.checkerframework.checker.nullness.qual.NonNull;
 import org.checkerframework.checker.nullness.qual.Nullable;
 import org.checkerframework.checker.nullness.qual.PolyNull;
+import org.checkerframework.checker.signedness.qual.UnknownSignedness;
 import org.checkerframework.framework.qual.AnnotatedFor;
 import org.checkerframework.framework.qual.Covariant;
 
@@ -314,7 +315,7 @@ public java.util.Optional<T> toJavaUtil() {
    * hash code unspecified, unlike the Java 8 equivalent.
    */
   @Override
-  public abstract int hashCode();
+  public abstract int hashCode(@UnknownSignedness Optional<T> this);
 
   /**
    * Returns a string representation for this instance.
diff --git a/guava/src/com/google/common/base/PairwiseEquivalence.java b/guava/src/com/google/common/base/PairwiseEquivalence.java
index 64b438bb9f1a..ac24f82aa6fd 100644
--- a/guava/src/com/google/common/base/PairwiseEquivalence.java
+++ b/guava/src/com/google/common/base/PairwiseEquivalence.java
@@ -19,6 +19,7 @@
 import java.util.Iterator;
 import javax.annotation.CheckForNull;
 import org.checkerframework.checker.nullness.qual.Nullable;
+import org.checkerframework.checker.signedness.qual.UnknownSignedness;
 
 @GwtCompatible(serializable = true)
 @ElementTypesAreNonnullByDefault
@@ -64,7 +65,7 @@ public boolean equals(@CheckForNull Object object) {
   }
 
   @Override
-  public int hashCode() {
+  public int hashCode(@UnknownSignedness PairwiseEquivalence<E, T> this) {
     return elementEquivalence.hashCode() ^ 0x46a3eb07;
   }
 
diff --git a/guava/src/com/google/common/base/Predicates.java b/guava/src/com/google/common/base/Predicates.java
index dc2548ad6192..c6f219597f80 100644
--- a/guava/src/com/google/common/base/Predicates.java
+++ b/guava/src/com/google/common/base/Predicates.java
@@ -27,6 +27,7 @@
 import java.util.regex.Pattern;
 import javax.annotation.CheckForNull;
 import org.checkerframework.checker.nullness.qual.Nullable;
+import org.checkerframework.checker.signedness.qual.UnknownSignedness;
 import org.checkerframework.dataflow.qual.Pure;
 import org.checkerframework.framework.qual.AnnotatedFor;
 
@@ -330,7 +331,7 @@ public boolean apply(@ParametricNullness T t) {
 
     @Pure
     @Override
-    public int hashCode() {
+    public int hashCode(@UnknownSignedness NotPredicate<T> this) {
       return ~predicate.hashCode();
     }
 
@@ -375,7 +376,7 @@ public boolean apply(@ParametricNullness T t) {
 
     @Pure
     @Override
-    public int hashCode() {
+    public int hashCode(@UnknownSignedness AndPredicate<T> this) {
       // add a random number to avoid collisions with OrPredicate
       return components.hashCode() + 0x12472c2c;
     }
@@ -421,7 +422,7 @@ public boolean apply(@ParametricNullness T t) {
 
     @Pure
     @Override
-    public int hashCode() {
+    public int hashCode(@UnknownSignedness OrPredicate<T> this) {
       // add a random number to avoid collisions with AndPredicate
       return components.hashCode() + 0x053c91cf;
     }
@@ -473,7 +474,7 @@ public boolean apply(@CheckForNull Object o) {
 
     @Pure
     @Override
-    public int hashCode() {
+    public int hashCode(@UnknownSignedness IsEqualToPredicate this) {
       return target.hashCode();
     }
 
@@ -518,7 +519,7 @@ public boolean apply(@ParametricNullness T o) {
 
     @Pure
     @Override
-    public int hashCode() {
+    public int hashCode(@UnknownSignedness InstanceOfPredicate<T> this) {
       return clazz.hashCode();
     }
 
@@ -556,7 +557,7 @@ public boolean apply(Class<?> input) {
     }
 
     @Override
-    public int hashCode() {
+    public int hashCode(@UnknownSignedness SubtypeOfPredicate this) {
       return clazz.hashCode();
     }
 
@@ -607,7 +608,7 @@ public boolean equals(@CheckForNull Object obj) {
 
     @Pure
     @Override
-    public int hashCode() {
+    public int hashCode(@UnknownSignedness InPredicate<T> this) {
       return target.hashCode();
     }
 
@@ -648,7 +649,7 @@ public boolean equals(@CheckForNull Object obj) {
 
     @Pure
     @Override
-    public int hashCode() {
+    public int hashCode(@UnknownSignedness CompositionPredicate<A, B> this) {
       return f.hashCode() ^ p.hashCode();
     }
 
@@ -677,7 +678,7 @@ public boolean apply(CharSequence t) {
     }
 
     @Override
-    public int hashCode() {
+    public int hashCode(@UnknownSignedness ContainsPatternPredicate this) {
       // Pattern uses Object.hashCode, so we have to reach
       // inside to build a hashCode consistent with equals.
 
diff --git a/guava/src/com/google/common/base/Present.java b/guava/src/com/google/common/base/Present.java
index 20ab94a2c2ec..60eef32d8398 100644
--- a/guava/src/com/google/common/base/Present.java
+++ b/guava/src/com/google/common/base/Present.java
@@ -22,6 +22,7 @@
 import javax.annotation.CheckForNull;
 
 import org.checkerframework.checker.nullness.qual.NonNull;
+import org.checkerframework.checker.signedness.qual.UnknownSignedness;
 
 /** Implementation of an {@link Optional} containing a reference. */
 @GwtCompatible
@@ -89,7 +90,7 @@ public boolean equals(@CheckForNull Object object) {
   }
 
   @Override
-  public int hashCode() {
+  public int hashCode(@UnknownSignedness Present<T> this) {
     return 0x598df91c + reference.hashCode();
   }
 
diff --git a/guava/src/com/google/common/base/Suppliers.java b/guava/src/com/google/common/base/Suppliers.java
index 4056f260f5f3..4b12eae90f45 100644
--- a/guava/src/com/google/common/base/Suppliers.java
+++ b/guava/src/com/google/common/base/Suppliers.java
@@ -25,6 +25,7 @@
 import java.util.concurrent.TimeUnit;
 import javax.annotation.CheckForNull;
 import org.checkerframework.checker.nullness.qual.Nullable;
+import org.checkerframework.checker.signedness.qual.UnknownSignedness;
 import org.checkerframework.framework.qual.AnnotatedFor;
 
 /**
@@ -79,7 +80,7 @@ public boolean equals(@CheckForNull Object obj) {
     }
 
     @Override
-    public int hashCode() {
+    public int hashCode(@UnknownSignedness SupplierComposition<F, T> this) {
       return Objects.hashCode(function, supplier);
     }
 
@@ -315,7 +316,7 @@ public boolean equals(@CheckForNull Object obj) {
     }
 
     @Override
-    public int hashCode() {
+    public int hashCode(@UnknownSignedness SupplierOfInstance<T> this) {
       return Objects.hashCode(instance);
     }
 
diff --git a/guava/src/com/google/common/cache/CacheBuilderSpec.java b/guava/src/com/google/common/cache/CacheBuilderSpec.java
index 3e5c1786c1c0..b8447a38a001 100644
--- a/guava/src/com/google/common/cache/CacheBuilderSpec.java
+++ b/guava/src/com/google/common/cache/CacheBuilderSpec.java
@@ -31,6 +31,7 @@
 import javax.annotation.CheckForNull;
 import org.checkerframework.checker.formatter.qual.FormatMethod;
 import org.checkerframework.checker.nullness.qual.Nullable;
+import org.checkerframework.checker.signedness.qual.UnknownSignedness;
 
 /**
  * A specification of a {@link CacheBuilder} configuration.
@@ -237,7 +238,7 @@ public String toString() {
   }
 
   @Override
-  public int hashCode() {
+  public int hashCode(@UnknownSignedness CacheBuilderSpec this) {
     return Objects.hashCode(
         initialCapacity,
         maximumSize,
diff --git a/guava/src/com/google/common/cache/CacheStats.java b/guava/src/com/google/common/cache/CacheStats.java
index 8307e942a818..4ed0854314be 100644
--- a/guava/src/com/google/common/cache/CacheStats.java
+++ b/guava/src/com/google/common/cache/CacheStats.java
@@ -23,6 +23,7 @@
 import com.google.common.base.Objects;
 import java.util.concurrent.Callable;
 import javax.annotation.CheckForNull;
+import org.checkerframework.checker.signedness.qual.UnknownSignedness;
 
 /**
  * Statistics about the performance of a {@link Cache}. Instances of this class are immutable.
@@ -271,7 +272,7 @@ public CacheStats plus(CacheStats other) {
   }
 
   @Override
-  public int hashCode() {
+  public int hashCode(@UnknownSignedness CacheStats this) {
     return Objects.hashCode(
         hitCount, missCount, loadSuccessCount, loadExceptionCount, totalLoadTime, evictionCount);
   }
diff --git a/guava/src/com/google/common/cache/LocalCache.java b/guava/src/com/google/common/cache/LocalCache.java
index 3ab2652d63ec..c9462c62a5c6 100644
--- a/guava/src/com/google/common/cache/LocalCache.java
+++ b/guava/src/com/google/common/cache/LocalCache.java
@@ -4487,7 +4487,7 @@ public boolean equals(@Nullable Object object) {
     }
 
     @Override
-    public int hashCode() {
+    public int hashCode(@UnknownSignedness WriteThroughEntry this) {
       // Cannot use key and value equivalence
       return key.hashCode() ^ value.hashCode();
     }
diff --git a/guava/src/com/google/common/collect/AbstractMapBasedMultimap.java b/guava/src/com/google/common/collect/AbstractMapBasedMultimap.java
index fca4a436dded..16f9cadc337e 100644
--- a/guava/src/com/google/common/collect/AbstractMapBasedMultimap.java
+++ b/guava/src/com/google/common/collect/AbstractMapBasedMultimap.java
@@ -413,7 +413,7 @@ public boolean equals(@CheckForNull @UnknownSignedness Object object) {
     }
 
     @Override
-    public int hashCode() {
+    public int hashCode(@UnknownSignedness WrappedCollection this) {
       refreshIfEmpty();
       return delegate.hashCode();
     }
@@ -1015,7 +1015,7 @@ public boolean equals(@CheckForNull @UnknownSignedness Object object) {
     }
 
     @Override
-    public int hashCode() {
+    public int hashCode(@UnknownSignedness KeySet this) {
       return map().keySet().hashCode();
     }
   }
@@ -1407,7 +1407,7 @@ public boolean equals(@CheckForNull Object object) {
     }
 
     @Override
-    public int hashCode() {
+    public int hashCode(@UnknownSignedness AsMap this) {
       return submap.hashCode();
     }
 
diff --git a/guava/src/com/google/common/collect/AbstractMapEntry.java b/guava/src/com/google/common/collect/AbstractMapEntry.java
index 1a370dc1a648..5819710f3c5a 100644
--- a/guava/src/com/google/common/collect/AbstractMapEntry.java
+++ b/guava/src/com/google/common/collect/AbstractMapEntry.java
@@ -21,6 +21,7 @@
 import java.util.Map.Entry;
 import javax.annotation.CheckForNull;
 import org.checkerframework.checker.nullness.qual.Nullable;
+import org.checkerframework.checker.signedness.qual.UnknownSignedness;
 import org.checkerframework.dataflow.qual.Pure;
 import org.checkerframework.framework.qual.AnnotatedFor;
 
@@ -65,7 +66,7 @@ public boolean equals(@CheckForNull Object object) {
 
   @Pure
   @Override
-  public int hashCode() {
+  public int hashCode(@UnknownSignedness AbstractMapEntry<K, V> this) {
     K k = getKey();
     V v = getValue();
     return ((k == null) ? 0 : k.hashCode()) ^ ((v == null) ? 0 : v.hashCode());
diff --git a/guava/src/com/google/common/collect/AbstractMultimap.java b/guava/src/com/google/common/collect/AbstractMultimap.java
index 6b09265972eb..db5a67f88e80 100644
--- a/guava/src/com/google/common/collect/AbstractMultimap.java
+++ b/guava/src/com/google/common/collect/AbstractMultimap.java
@@ -153,7 +153,7 @@ public Spliterator<Entry<K, V>> spliterator() {
   class EntrySet extends Entries implements Set<Entry<K, V>> {
     @Pure
     @Override
-    public int hashCode() {
+    public int hashCode(@UnknownSignedness EntrySet this) {
       return Sets.hashCodeImpl(this);
     }
 
@@ -270,7 +270,7 @@ public boolean equals(@CheckForNull Object object) {
    */
   @Pure
   @Override
-  public int hashCode() {
+  public int hashCode(@UnknownSignedness AbstractMultimap<K, V> this) {
     return asMap().hashCode();
   }
 
diff --git a/guava/src/com/google/common/collect/AbstractMultiset.java b/guava/src/com/google/common/collect/AbstractMultiset.java
index d7f0015136a9..4266d7a318b1 100644
--- a/guava/src/com/google/common/collect/AbstractMultiset.java
+++ b/guava/src/com/google/common/collect/AbstractMultiset.java
@@ -229,7 +229,7 @@ public final boolean equals(@CheckForNull @UnknownSignedness Object object) {
    */
   @Pure
   @Override
-  public final int hashCode() {
+  public final int hashCode(@UnknownSignedness AbstractMultiset<E> this) {
     return entrySet().hashCode();
   }
 
diff --git a/guava/src/com/google/common/collect/AbstractRangeSet.java b/guava/src/com/google/common/collect/AbstractRangeSet.java
index d112a11f1814..69a93db47e11 100644
--- a/guava/src/com/google/common/collect/AbstractRangeSet.java
+++ b/guava/src/com/google/common/collect/AbstractRangeSet.java
@@ -16,6 +16,7 @@
 
 import com.google.common.annotations.GwtIncompatible;
 import javax.annotation.CheckForNull;
+import org.checkerframework.checker.signedness.qual.UnknownSignedness;
 
 /**
  * A skeletal implementation of {@code RangeSet}.
@@ -91,7 +92,7 @@ public boolean equals(@CheckForNull Object obj) {
   }
 
   @Override
-  public final int hashCode() {
+  public final int hashCode(@UnknownSignedness AbstractRangeSet<C> this) {
     return asRanges().hashCode();
   }
 
diff --git a/guava/src/com/google/common/collect/AbstractTable.java b/guava/src/com/google/common/collect/AbstractTable.java
index 95cb55180f0c..97ce8fbeffcf 100644
--- a/guava/src/com/google/common/collect/AbstractTable.java
+++ b/guava/src/com/google/common/collect/AbstractTable.java
@@ -240,7 +240,7 @@ public boolean equals(@CheckForNull Object obj) {
   }
 
   @Override
-  public int hashCode() {
+  public int hashCode(@UnknownSignedness AbstractTable<R, C, V> this) {
     return cellSet().hashCode();
   }
 
diff --git a/guava/src/com/google/common/collect/ByFunctionOrdering.java b/guava/src/com/google/common/collect/ByFunctionOrdering.java
index f72238380ed1..27f57d45cfc4 100644
--- a/guava/src/com/google/common/collect/ByFunctionOrdering.java
+++ b/guava/src/com/google/common/collect/ByFunctionOrdering.java
@@ -24,6 +24,7 @@
 import java.io.Serializable;
 import javax.annotation.CheckForNull;
 import org.checkerframework.checker.nullness.qual.Nullable;
+import org.checkerframework.checker.signedness.qual.UnknownSignedness;
 import org.checkerframework.dataflow.qual.Pure;
 import org.checkerframework.framework.qual.AnnotatedFor;
 
@@ -65,7 +66,7 @@ public boolean equals(@CheckForNull Object object) {
 
   @Pure
   @Override
-  public int hashCode() {
+  public int hashCode(@UnknownSignedness ByFunctionOrdering<F, T> this) {
     return Objects.hashCode(function, ordering);
   }
 
diff --git a/guava/src/com/google/common/collect/CartesianList.java b/guava/src/com/google/common/collect/CartesianList.java
index beaa71675113..e14fb959fae2 100644
--- a/guava/src/com/google/common/collect/CartesianList.java
+++ b/guava/src/com/google/common/collect/CartesianList.java
@@ -24,6 +24,7 @@
 import java.util.RandomAccess;
 import javax.annotation.CheckForNull;
 import org.checkerframework.checker.index.qual.NonNegative;
+import org.checkerframework.checker.signedness.qual.UnknownSignedness;
 
 /**
  * Implementation of {@link Lists#cartesianProduct(List)}.
@@ -69,7 +70,7 @@ private int getAxisIndexForProductIndex(int index, int axis) {
   }
 
   @Override
-  public int indexOf(@CheckForNull Object o) {
+  public int indexOf(@CheckForNull @UnknownSignedness Object o) {
     if (!(o instanceof List)) {
       return -1;
     }
@@ -91,7 +92,7 @@ public int indexOf(@CheckForNull Object o) {
   }
 
   @Override
-  public int lastIndexOf(@CheckForNull Object o) {
+  public int lastIndexOf(@CheckForNull @UnknownSignedness Object o) {
     if (!(o instanceof List)) {
       return -1;
     }
@@ -142,7 +143,7 @@ boolean isPartialView() {
   }
 
   @Override
-  public boolean contains(@CheckForNull Object object) {
+  public boolean contains(@CheckForNull @UnknownSignedness Object object) {
     if (!(object instanceof List)) {
       return false;
     }
diff --git a/guava/src/com/google/common/collect/ComparatorOrdering.java b/guava/src/com/google/common/collect/ComparatorOrdering.java
index e021ddb90fec..d0df4a70bca9 100644
--- a/guava/src/com/google/common/collect/ComparatorOrdering.java
+++ b/guava/src/com/google/common/collect/ComparatorOrdering.java
@@ -23,6 +23,7 @@
 import java.util.Comparator;
 import javax.annotation.CheckForNull;
 import org.checkerframework.checker.nullness.qual.Nullable;
+import org.checkerframework.checker.signedness.qual.UnknownSignedness;
 import org.checkerframework.dataflow.qual.Pure;
 import org.checkerframework.framework.qual.AnnotatedFor;
 
@@ -59,7 +60,7 @@ public boolean equals(@CheckForNull Object object) {
 
   @Pure
   @Override
-  public int hashCode() {
+  public int hashCode(@UnknownSignedness ComparatorOrdering<T> this) {
     return comparator.hashCode();
   }
 
diff --git a/guava/src/com/google/common/collect/CompoundOrdering.java b/guava/src/com/google/common/collect/CompoundOrdering.java
index e8732b015ee5..63690d37219c 100644
--- a/guava/src/com/google/common/collect/CompoundOrdering.java
+++ b/guava/src/com/google/common/collect/CompoundOrdering.java
@@ -22,6 +22,7 @@
 import java.util.Comparator;
 import javax.annotation.CheckForNull;
 import org.checkerframework.checker.nullness.qual.Nullable;
+import org.checkerframework.checker.signedness.qual.UnknownSignedness;
 import org.checkerframework.dataflow.qual.Pure;
 import org.checkerframework.framework.qual.AnnotatedFor;
 
@@ -68,7 +69,7 @@ public boolean equals(@CheckForNull Object object) {
 
   @Pure
   @Override
-  public int hashCode() {
+  public int hashCode(@UnknownSignedness CompoundOrdering<T> this) {
     return Arrays.hashCode(comparators);
   }
 
diff --git a/guava/src/com/google/common/collect/ConcurrentHashMultiset.java b/guava/src/com/google/common/collect/ConcurrentHashMultiset.java
index 665c4e115e74..2a9a016bdef2 100644
--- a/guava/src/com/google/common/collect/ConcurrentHashMultiset.java
+++ b/guava/src/com/google/common/collect/ConcurrentHashMultiset.java
@@ -466,7 +466,7 @@ protected Set<E> delegate() {
       }
 
       @Override
-      public boolean contains(@CheckForNull Object object) {
+      public boolean contains(@CheckForNull @UnknownSignedness Object object) {
         return object != null && Collections2.safeContains(delegate, object);
       }
 
@@ -610,7 +610,7 @@ private List<Multiset.Entry<E>> snapshot() {
 
   @Pure
   @Override
-  public boolean contains(@Nullable Object arg0) { return super.contains(arg0); }
+  public boolean contains(@Nullable @UnknownSignedness Object arg0) { return super.contains(arg0); }
 
   @Pure
   @Override
@@ -634,7 +634,7 @@ private void readObject(ObjectInputStream stream) throws IOException, ClassNotFo
   private static final long serialVersionUID = 1;
 
 @Override
-public boolean contains(@Nullable Object arg0) { return super.contains(arg0); }
+public boolean contains(@Nullable @UnknownSignedness Object arg0) { return super.contains(arg0); }
 
 @Pure
 @Override
diff --git a/guava/src/com/google/common/collect/Count.java b/guava/src/com/google/common/collect/Count.java
index 7aa555080135..0b819a3b5272 100644
--- a/guava/src/com/google/common/collect/Count.java
+++ b/guava/src/com/google/common/collect/Count.java
@@ -17,6 +17,7 @@
 import com.google.common.annotations.GwtCompatible;
 import java.io.Serializable;
 import javax.annotation.CheckForNull;
+import org.checkerframework.checker.signedness.qual.UnknownSignedness;
 
 /**
  * A mutable value of type {@code int}, for multisets to use in tracking counts of values.
@@ -55,7 +56,7 @@ public int getAndSet(int newValue) {
   }
 
   @Override
-  public int hashCode() {
+  public int hashCode(@UnknownSignedness Count this) {
     return value;
   }
 
diff --git a/guava/src/com/google/common/collect/Cut.java b/guava/src/com/google/common/collect/Cut.java
index 21fe5ff2dd9f..88fbbc8797c2 100644
--- a/guava/src/com/google/common/collect/Cut.java
+++ b/guava/src/com/google/common/collect/Cut.java
@@ -21,6 +21,7 @@
 import java.io.Serializable;
 import java.util.NoSuchElementException;
 import javax.annotation.CheckForNull;
+import org.checkerframework.checker.signedness.qual.UnknownSignedness;
 
 /**
  * Implementation detail for the internal structure of {@link Range} instances. Represents a unique
@@ -107,7 +108,7 @@ public boolean equals(@CheckForNull Object obj) {
 
   // Prevent "missing hashCode" warning by explicitly forcing subclasses implement it
   @Override
-  public abstract int hashCode();
+  public abstract int hashCode(@UnknownSignedness Cut<C> this);
 
   /*
    * The implementation neither produces nor consumes any non-null instance of type C, so
@@ -200,7 +201,7 @@ public int compareTo(Cut<Comparable<?>> o) {
     }
 
     @Override
-    public int hashCode() {
+    public int hashCode(@UnknownSignedness BelowAll this) {
       return System.identityHashCode(this);
     }
 
@@ -291,7 +292,7 @@ public int compareTo(Cut<Comparable<?>> o) {
     }
 
     @Override
-    public int hashCode() {
+    public int hashCode(@UnknownSignedness AboveAll this) {
       return System.identityHashCode(this);
     }
 
@@ -379,7 +380,7 @@ C greatestValueBelow(DiscreteDomain<C> domain) {
     }
 
     @Override
-    public int hashCode() {
+    public int hashCode(@UnknownSignedness BelowValue<C> this) {
       return endpoint.hashCode();
     }
 
@@ -469,7 +470,7 @@ Cut<C> canonical(DiscreteDomain<C> domain) {
     }
 
     @Override
-    public int hashCode() {
+    public int hashCode(@UnknownSignedness AboveValue<C> this) {
       return ~endpoint.hashCode();
     }
 
diff --git a/guava/src/com/google/common/collect/DenseImmutableTable.java b/guava/src/com/google/common/collect/DenseImmutableTable.java
index 9c20b45089a2..4abf1eb81c76 100644
--- a/guava/src/com/google/common/collect/DenseImmutableTable.java
+++ b/guava/src/com/google/common/collect/DenseImmutableTable.java
@@ -24,6 +24,7 @@
 import javax.annotation.CheckForNull;
 import org.checkerframework.checker.index.qual.NonNegative;
 import org.checkerframework.checker.nullness.qual.Nullable;
+import org.checkerframework.checker.signedness.qual.UnknownSignedness;
 
 /** A {@code RegularImmutableTable} optimized for dense data. */
 @GwtCompatible
@@ -121,7 +122,7 @@ ImmutableSet<K> createKeySet() {
 
     @Override
     @CheckForNull
-    public V get(@CheckForNull Object key) {
+    public V get(@CheckForNull @UnknownSignedness Object key) {
       Integer keyIndex = keyToIndex().get(key);
       return (keyIndex == null) ? null : getValue(keyIndex);
     }
diff --git a/guava/src/com/google/common/collect/DescendingImmutableSortedSet.java b/guava/src/com/google/common/collect/DescendingImmutableSortedSet.java
index be03268fa17e..235812e9d6c6 100644
--- a/guava/src/com/google/common/collect/DescendingImmutableSortedSet.java
+++ b/guava/src/com/google/common/collect/DescendingImmutableSortedSet.java
@@ -19,6 +19,7 @@
 import com.google.common.annotations.GwtIncompatible;
 import javax.annotation.CheckForNull;
 import org.checkerframework.checker.index.qual.NonNegative;
+import org.checkerframework.checker.signedness.qual.UnknownSignedness;
 
 /**
  * Skeletal implementation of {@link ImmutableSortedSet#descendingSet()}.
@@ -36,7 +37,7 @@ final class DescendingImmutableSortedSet<E> extends ImmutableSortedSet<E> {
   }
 
   @Override
-  public boolean contains(@CheckForNull Object object) {
+  public boolean contains(@CheckForNull @UnknownSignedness Object object) {
     return forward.contains(object);
   }
 
diff --git a/guava/src/com/google/common/collect/DescendingMultiset.java b/guava/src/com/google/common/collect/DescendingMultiset.java
index e57fa6c88c8a..cec800966835 100644
--- a/guava/src/com/google/common/collect/DescendingMultiset.java
+++ b/guava/src/com/google/common/collect/DescendingMultiset.java
@@ -27,6 +27,7 @@
 import org.checkerframework.checker.nullness.qual.Nullable;
 import org.checkerframework.checker.nullness.qual.PolyNull;
 import org.checkerframework.checker.signedness.qual.PolySigned;
+import org.checkerframework.checker.signedness.qual.UnknownSignedness;
 
 /**
  * A skeleton implementation of a descending multiset. Only needs {@code forwardMultiset()} and
@@ -160,7 +161,7 @@ public Iterator<E> iterator() {
 
   @Override
   @SuppressWarnings("nullness") // b/192354773 in our checker affects toArray declarations
-  public <T extends @Nullable Object> T[] toArray(T[] array) {
+  public <T extends @Nullable @UnknownSignedness Object> T[] toArray(@PolyNull T[] array) {
     return standardToArray(array);
   }
 
diff --git a/guava/src/com/google/common/collect/EmptyContiguousSet.java b/guava/src/com/google/common/collect/EmptyContiguousSet.java
index 095d981de8a2..af2397fc0fa5 100644
--- a/guava/src/com/google/common/collect/EmptyContiguousSet.java
+++ b/guava/src/com/google/common/collect/EmptyContiguousSet.java
@@ -20,6 +20,7 @@
 import java.util.Set;
 import javax.annotation.CheckForNull;
 import org.checkerframework.checker.index.qual.NonNegative;
+import org.checkerframework.checker.signedness.qual.UnknownSignedness;
 
 /**
  * An empty contiguous set.
@@ -81,7 +82,7 @@ ContiguousSet<C> tailSetImpl(C fromElement, boolean fromInclusive) {
   }
 
   @Override
-  public boolean contains(@CheckForNull Object object) {
+  public boolean contains(@CheckForNull @UnknownSignedness Object object) {
     return false;
   }
 
@@ -123,7 +124,7 @@ public String toString() {
   }
 
   @Override
-  public boolean equals(@CheckForNull Object object) {
+  public boolean equals(@CheckForNull @UnknownSignedness Object object) {
     if (object instanceof Set) {
       Set<?> that = (Set<?>) object;
       return that.isEmpty();
@@ -138,7 +139,7 @@ boolean isHashCodeFast() {
   }
 
   @Override
-  public int hashCode() {
+  public int hashCode(@UnknownSignedness EmptyContiguousSet<C> this) {
     return 0;
   }
 
diff --git a/guava/src/com/google/common/collect/EnumMultiset.java b/guava/src/com/google/common/collect/EnumMultiset.java
index 2ca1e895ca1c..022ccde06600 100644
--- a/guava/src/com/google/common/collect/EnumMultiset.java
+++ b/guava/src/com/google/common/collect/EnumMultiset.java
@@ -326,7 +326,7 @@ private void readObject(ObjectInputStream stream) throws IOException, ClassNotFo
 
   @Pure
   @Override
-  public boolean contains(@Nullable Object arg0) { return super.contains(arg0); }
+  public boolean contains(@Nullable @UnknownSignedness Object arg0) { return super.contains(arg0); }
 
   @Pure
   @Override
diff --git a/guava/src/com/google/common/collect/ExplicitOrdering.java b/guava/src/com/google/common/collect/ExplicitOrdering.java
index 695903654481..8f6454b6c01d 100644
--- a/guava/src/com/google/common/collect/ExplicitOrdering.java
+++ b/guava/src/com/google/common/collect/ExplicitOrdering.java
@@ -21,6 +21,7 @@
 import java.util.List;
 import javax.annotation.CheckForNull;
 import org.checkerframework.checker.nullness.qual.Nullable;
+import org.checkerframework.checker.signedness.qual.UnknownSignedness;
 import org.checkerframework.dataflow.qual.Pure;
 import org.checkerframework.framework.qual.AnnotatedFor;
 
@@ -65,7 +66,7 @@ public boolean equals(@CheckForNull Object object) {
 
   @Pure
   @Override
-  public int hashCode() {
+  public int hashCode(@UnknownSignedness ExplicitOrdering<T> this) {
     return rankMap.hashCode();
   }
 
diff --git a/guava/src/com/google/common/collect/FilteredEntryMultimap.java b/guava/src/com/google/common/collect/FilteredEntryMultimap.java
index becc1ddaccf8..f76c2ab90f4d 100644
--- a/guava/src/com/google/common/collect/FilteredEntryMultimap.java
+++ b/guava/src/com/google/common/collect/FilteredEntryMultimap.java
@@ -182,7 +182,7 @@ public void clear() {
 
     @Override
     @CheckForNull
-    public Collection<V> get(@CheckForNull Object key) {
+    public Collection<V> get(@CheckForNull @UnknownSignedness Object key) {
       Collection<V> result = unfiltered.asMap().get(key);
       if (result == null) {
         return null;
@@ -195,7 +195,7 @@ public Collection<V> get(@CheckForNull Object key) {
 
     @Override
     @CheckForNull
-    public Collection<V> remove(@CheckForNull Object key) {
+    public Collection<V> remove(@CheckForNull @UnknownSignedness Object key) {
       Collection<V> collection = unfiltered.asMap().get(key);
       if (collection == null) {
         return null;
diff --git a/guava/src/com/google/common/collect/FilteredKeySetMultimap.java b/guava/src/com/google/common/collect/FilteredKeySetMultimap.java
index e492a5c1dea9..22b4028142f9 100644
--- a/guava/src/com/google/common/collect/FilteredKeySetMultimap.java
+++ b/guava/src/com/google/common/collect/FilteredKeySetMultimap.java
@@ -22,6 +22,7 @@
 import java.util.Set;
 import javax.annotation.CheckForNull;
 import org.checkerframework.checker.nullness.qual.Nullable;
+import org.checkerframework.checker.signedness.qual.UnknownSignedness;
 
 /**
  * Implementation of {@link Multimaps#filterKeys(SetMultimap, Predicate)}.
@@ -69,12 +70,12 @@ Set<Entry<K, V>> createEntries() {
 
   class EntrySet extends Entries implements Set<Entry<K, V>> {
     @Override
-    public int hashCode() {
+    public int hashCode(@UnknownSignedness EntrySet this) {
       return Sets.hashCodeImpl(this);
     }
 
     @Override
-    public boolean equals(@CheckForNull Object o) {
+    public boolean equals(@CheckForNull @UnknownSignedness Object o) {
       return Sets.equalsImpl(this, o);
     }
   }
diff --git a/guava/src/com/google/common/collect/FilteredMultimapValues.java b/guava/src/com/google/common/collect/FilteredMultimapValues.java
index de500e326bff..5954d651e677 100644
--- a/guava/src/com/google/common/collect/FilteredMultimapValues.java
+++ b/guava/src/com/google/common/collect/FilteredMultimapValues.java
@@ -51,7 +51,7 @@ public Iterator<V> iterator() {
   }
 
   @Override
-  public boolean contains(@CheckForNull Object o) {
+  public boolean contains(@CheckForNull @UnknownSignedness Object o) {
     return multimap.containsValue(o);
   }
 
diff --git a/guava/src/com/google/common/collect/ForwardingConcurrentMap.java b/guava/src/com/google/common/collect/ForwardingConcurrentMap.java
index 2d8445e04ef9..e3dc0ee2e259 100644
--- a/guava/src/com/google/common/collect/ForwardingConcurrentMap.java
+++ b/guava/src/com/google/common/collect/ForwardingConcurrentMap.java
@@ -21,6 +21,7 @@
 import java.util.concurrent.ConcurrentMap;
 import javax.annotation.CheckForNull;
 import org.checkerframework.checker.nullness.qual.Nullable;
+import org.checkerframework.checker.signedness.qual.UnknownSignedness;
 import org.checkerframework.framework.qual.AnnotatedFor;
 
 /**
@@ -61,7 +62,7 @@ public V putIfAbsent(K key, V value) {
   @CanIgnoreReturnValue
   @Override
   @SuppressWarnings("nullness:argument")
-  public boolean remove(@CheckForNull Object key, @CheckForNull Object value) {
+  public boolean remove(@CheckForNull @UnknownSignedness Object key, @CheckForNull @UnknownSignedness Object value) {
     return delegate().remove(key, value);
   }
 
diff --git a/guava/src/com/google/common/collect/ForwardingList.java b/guava/src/com/google/common/collect/ForwardingList.java
index 13865bf50926..d20eb3624c2e 100644
--- a/guava/src/com/google/common/collect/ForwardingList.java
+++ b/guava/src/com/google/common/collect/ForwardingList.java
@@ -25,6 +25,7 @@
 import java.util.ListIterator;
 import javax.annotation.CheckForNull;
 import org.checkerframework.checker.nullness.qual.Nullable;
+import org.checkerframework.checker.signedness.qual.UnknownSignedness;
 import org.checkerframework.dataflow.qual.Pure;
 import org.checkerframework.dataflow.qual.SideEffectFree;
 import org.checkerframework.framework.qual.AnnotatedFor;
@@ -87,14 +88,14 @@ public E get(int index) {
   @Pure
   @Override
   @SuppressWarnings("nullness:argument")
-  public int indexOf(@CheckForNull Object element) {
+  public int indexOf(@CheckForNull @UnknownSignedness Object element) {
     return delegate().indexOf(element);
   }
 
   @Pure
   @Override
   @SuppressWarnings("nullness:argument")
-  public int lastIndexOf(@CheckForNull Object element) {
+  public int lastIndexOf(@CheckForNull @UnknownSignedness Object element) {
     return delegate().lastIndexOf(element);
   }
 
@@ -130,13 +131,13 @@ public List<E> subList(int fromIndex, int toIndex) {
 
   @Pure
   @Override
-  public boolean equals(@CheckForNull Object object) {
+  public boolean equals(@CheckForNull @UnknownSignedness Object object) {
     return object == this || delegate().equals(object);
   }
 
   @Pure
   @Override
-  public int hashCode() {
+  public int hashCode(@UnknownSignedness ForwardingList<E> this) {
     return delegate().hashCode();
   }
 
diff --git a/guava/src/com/google/common/collect/ForwardingMap.java b/guava/src/com/google/common/collect/ForwardingMap.java
index 149b205a4c3c..295f31dfd02d 100644
--- a/guava/src/com/google/common/collect/ForwardingMap.java
+++ b/guava/src/com/google/common/collect/ForwardingMap.java
@@ -159,7 +159,7 @@ public boolean equals(@CheckForNull Object object) {
 
   @Pure
   @Override
-  public int hashCode() {
+  public int hashCode(@UnknownSignedness ForwardingMap<K, V> this) {
     return delegate().hashCode();
   }
 
diff --git a/guava/src/com/google/common/collect/ForwardingMapEntry.java b/guava/src/com/google/common/collect/ForwardingMapEntry.java
index c1f6cf19ef84..a8fec1c83229 100644
--- a/guava/src/com/google/common/collect/ForwardingMapEntry.java
+++ b/guava/src/com/google/common/collect/ForwardingMapEntry.java
@@ -23,6 +23,7 @@
 import java.util.Map.Entry;
 import javax.annotation.CheckForNull;
 import org.checkerframework.checker.nullness.qual.Nullable;
+import org.checkerframework.checker.signedness.qual.UnknownSignedness;
 import org.checkerframework.dataflow.qual.Pure;
 import org.checkerframework.framework.qual.AnnotatedFor;
 
@@ -90,7 +91,7 @@ public boolean equals(@CheckForNull Object object) {
 
   @Pure
   @Override
-  public int hashCode() {
+  public int hashCode(@UnknownSignedness ForwardingMapEntry<K, V> this) {
     return delegate().hashCode();
   }
 
diff --git a/guava/src/com/google/common/collect/ForwardingMultimap.java b/guava/src/com/google/common/collect/ForwardingMultimap.java
index a72f94b74f44..735ff22e4131 100644
--- a/guava/src/com/google/common/collect/ForwardingMultimap.java
+++ b/guava/src/com/google/common/collect/ForwardingMultimap.java
@@ -165,7 +165,7 @@ public boolean equals(@CheckForNull Object object) {
 
   @Pure
   @Override
-  public int hashCode() {
+  public int hashCode(@UnknownSignedness ForwardingMultimap<K, V> this) {
     return delegate().hashCode();
   }
 }
diff --git a/guava/src/com/google/common/collect/ForwardingMultiset.java b/guava/src/com/google/common/collect/ForwardingMultiset.java
index 85680eeb50ae..2a3191724ca3 100644
--- a/guava/src/com/google/common/collect/ForwardingMultiset.java
+++ b/guava/src/com/google/common/collect/ForwardingMultiset.java
@@ -102,7 +102,7 @@ public boolean equals(@CheckForNull @UnknownSignedness Object object) {
 
   @Pure
   @Override
-  public int hashCode() {
+  public int hashCode(@UnknownSignedness ForwardingMultiset<E> this) {
     return delegate().hashCode();
   }
 
diff --git a/guava/src/com/google/common/collect/ForwardingSet.java b/guava/src/com/google/common/collect/ForwardingSet.java
index 857e7fb98b91..16d0e135ff86 100644
--- a/guava/src/com/google/common/collect/ForwardingSet.java
+++ b/guava/src/com/google/common/collect/ForwardingSet.java
@@ -70,7 +70,7 @@ public boolean equals(@CheckForNull @UnknownSignedness Object object) {
 
   @Pure
   @Override
-  public int hashCode() {
+  public int hashCode(@UnknownSignedness ForwardingSet<E> this) {
     return delegate().hashCode();
   }
 
diff --git a/guava/src/com/google/common/collect/ForwardingTable.java b/guava/src/com/google/common/collect/ForwardingTable.java
index ef9897cd3744..969118d81f2c 100644
--- a/guava/src/com/google/common/collect/ForwardingTable.java
+++ b/guava/src/com/google/common/collect/ForwardingTable.java
@@ -151,7 +151,7 @@ public boolean equals(@CheckForNull Object obj) {
   }
 
   @Override
-  public int hashCode() {
+  public int hashCode(@UnknownSignedness ForwardingTable<R, C, V> this) {
     return delegate().hashCode();
   }
 }
diff --git a/guava/src/com/google/common/collect/GeneralRange.java b/guava/src/com/google/common/collect/GeneralRange.java
index 3d7256ff811f..f99fafa0ae15 100644
--- a/guava/src/com/google/common/collect/GeneralRange.java
+++ b/guava/src/com/google/common/collect/GeneralRange.java
@@ -26,6 +26,7 @@
 import java.util.Comparator;
 import javax.annotation.CheckForNull;
 import org.checkerframework.checker.nullness.qual.Nullable;
+import org.checkerframework.checker.signedness.qual.UnknownSignedness;
 
 /**
  * A generalized interval on any ordering, for internal use. Supports {@code null}. Unlike {@link
@@ -252,7 +253,7 @@ && getUpperBoundType().equals(r.getUpperBoundType())
   }
 
   @Override
-  public int hashCode() {
+  public int hashCode(@UnknownSignedness GeneralRange<T> this) {
     return Objects.hashCode(
         comparator,
         getLowerEndpoint(),
diff --git a/guava/src/com/google/common/collect/HashBiMap.java b/guava/src/com/google/common/collect/HashBiMap.java
index 6e2ecd5fffa1..fe19cdb936f5 100644
--- a/guava/src/com/google/common/collect/HashBiMap.java
+++ b/guava/src/com/google/common/collect/HashBiMap.java
@@ -287,7 +287,7 @@ public boolean containsValue(@CheckForNull @UnknownSignedness Object value) {
 
   @Override
   @CheckForNull
-  public V get(@CheckForNull Object key) {
+  public V get(@CheckForNull @UnknownSignedness Object key) {
     return Maps.valueOrNull(seekByKey(key, smearedHash(key)));
   }
 
@@ -626,7 +626,7 @@ public boolean containsKey(@CheckForNull @UnknownSignedness Object value) {
 
     @Override
     @CheckForNull
-    public K get(@CheckForNull Object value) {
+    public K get(@CheckForNull @UnknownSignedness Object value) {
       return Maps.keyOrNull(seekByValue(value, smearedHash(value)));
     }
 
diff --git a/guava/src/com/google/common/collect/HashMultiset.java b/guava/src/com/google/common/collect/HashMultiset.java
index 7250d0da5559..20edf8de93eb 100644
--- a/guava/src/com/google/common/collect/HashMultiset.java
+++ b/guava/src/com/google/common/collect/HashMultiset.java
@@ -99,7 +99,7 @@ private void readObject(ObjectInputStream stream) throws IOException, ClassNotFo
   private static final long serialVersionUID = 0;
 
 @Override
-public boolean contains(@Nullable Object arg0) { return super.contains(arg0); }
+public boolean contains(@Nullable @UnknownSignedness Object arg0) { return super.contains(arg0); }
 
 @Override
 public @NonNegative int count(@Nullable @UnknownSignedness Object arg0) { return super.count(arg0); }
diff --git a/guava/src/com/google/common/collect/ImmutableEnumMap.java b/guava/src/com/google/common/collect/ImmutableEnumMap.java
index 163a9c723422..e7ad26df0ede 100644
--- a/guava/src/com/google/common/collect/ImmutableEnumMap.java
+++ b/guava/src/com/google/common/collect/ImmutableEnumMap.java
@@ -78,7 +78,7 @@ public boolean containsKey(@CheckForNull @UnknownSignedness Object key) {
 
   @Override
   @CheckForNull
-  public V get(@CheckForNull Object key) {
+  public V get(@CheckForNull @UnknownSignedness Object key) {
     return delegate.get(key);
   }
 
diff --git a/guava/src/com/google/common/collect/ImmutableEnumSet.java b/guava/src/com/google/common/collect/ImmutableEnumSet.java
index 3468009804ad..eee1bf09a3dc 100644
--- a/guava/src/com/google/common/collect/ImmutableEnumSet.java
+++ b/guava/src/com/google/common/collect/ImmutableEnumSet.java
@@ -26,6 +26,7 @@
 import javax.annotation.CheckForNull;
 import org.checkerframework.checker.index.qual.NonNegative;
 import org.checkerframework.checker.nullness.qual.Nullable;
+import org.checkerframework.checker.signedness.qual.UnknownSignedness;
 import org.checkerframework.dataflow.qual.Pure;
 import org.checkerframework.framework.qual.AnnotatedFor;
 
@@ -93,7 +94,7 @@ public void forEach(Consumer<? super E> action) {
 
   @Pure
   @Override
-  public boolean contains(@CheckForNull Object object) {
+  public boolean contains(@CheckForNull @UnknownSignedness Object object) {
     return delegate.contains(object);
   }
 
@@ -114,7 +115,7 @@ public boolean isEmpty() {
 
   @Pure
   @Override
-  public boolean equals(@CheckForNull Object object) {
+  public boolean equals(@CheckForNull @UnknownSignedness Object object) {
     if (object == this) {
       return true;
     }
@@ -133,7 +134,7 @@ boolean isHashCodeFast() {
 
   @Pure
   @Override
-  public int hashCode() {
+  public int hashCode(@UnknownSignedness ImmutableEnumSet<E> this) {
     int result = hashCode;
     return (result == 0) ? hashCode = delegate.hashCode() : result;
   }
diff --git a/guava/src/com/google/common/collect/ImmutableList.java b/guava/src/com/google/common/collect/ImmutableList.java
index b83219680929..1da52b5225cd 100644
--- a/guava/src/com/google/common/collect/ImmutableList.java
+++ b/guava/src/com/google/common/collect/ImmutableList.java
@@ -702,7 +702,7 @@ public boolean equals(@CheckForNull @UnknownSignedness Object obj) {
   }
 
   @Override
-  public int hashCode() {
+  public int hashCode(@UnknownSignedness ImmutableList<E> this) {
     int hashCode = 1;
     int n = size();
     for (int i = 0; i < n; i++) {
diff --git a/guava/src/com/google/common/collect/ImmutableMap.java b/guava/src/com/google/common/collect/ImmutableMap.java
index 36cc47e8e3fe..f827546e1a1c 100644
--- a/guava/src/com/google/common/collect/ImmutableMap.java
+++ b/guava/src/com/google/common/collect/ImmutableMap.java
@@ -1143,7 +1143,7 @@ boolean isPartialView() {
     }
 
     @Override
-    public int hashCode() {
+    public int hashCode(@UnknownSignedness ImmutableMap<K, V>.MapViewOfValuesAsSingletonSets this) {
       // ImmutableSet.of(value).hashCode() == value.hashCode(), so the hashes are the same
       return ImmutableMap.this.hashCode();
     }
@@ -1191,7 +1191,7 @@ public boolean equals(@CheckForNull Object object) {
 
   @Pure
   @Override
-  public int hashCode() {
+  public int hashCode(@UnknownSignedness ImmutableMap<K, V> this) {
     return Sets.hashCodeImpl(entrySet());
   }
 
diff --git a/guava/src/com/google/common/collect/ImmutableMapEntrySet.java b/guava/src/com/google/common/collect/ImmutableMapEntrySet.java
index 2329d2eb52d0..fec6d1525a6d 100644
--- a/guava/src/com/google/common/collect/ImmutableMapEntrySet.java
+++ b/guava/src/com/google/common/collect/ImmutableMapEntrySet.java
@@ -112,7 +112,7 @@ boolean isHashCodeFast() {
   }
 
   @Override
-  public int hashCode() {
+  public int hashCode(@UnknownSignedness ImmutableMapEntrySet<K, V> this) {
     return map().hashCode();
   }
 
diff --git a/guava/src/com/google/common/collect/ImmutableMapKeySet.java b/guava/src/com/google/common/collect/ImmutableMapKeySet.java
index e41a1942d158..ef845fdf3529 100644
--- a/guava/src/com/google/common/collect/ImmutableMapKeySet.java
+++ b/guava/src/com/google/common/collect/ImmutableMapKeySet.java
@@ -25,6 +25,7 @@
 import java.util.function.Consumer;
 import javax.annotation.CheckForNull;
 import org.checkerframework.checker.index.qual.NonNegative;
+import org.checkerframework.checker.signedness.qual.UnknownSignedness;
 
 /**
  * {@code keySet()} implementation for {@link ImmutableMap}.
@@ -57,7 +58,7 @@ public Spliterator<K> spliterator() {
   }
 
   @Override
-  public boolean contains(@CheckForNull Object object) {
+  public boolean contains(@CheckForNull @UnknownSignedness Object object) {
     return map.containsKey(object);
   }
 
diff --git a/guava/src/com/google/common/collect/ImmutableMapValues.java b/guava/src/com/google/common/collect/ImmutableMapValues.java
index f23f510212cc..cfa905e7d2ea 100644
--- a/guava/src/com/google/common/collect/ImmutableMapValues.java
+++ b/guava/src/com/google/common/collect/ImmutableMapValues.java
@@ -26,6 +26,7 @@
 import java.util.function.Consumer;
 import javax.annotation.CheckForNull;
 import org.checkerframework.checker.index.qual.NonNegative;
+import org.checkerframework.checker.signedness.qual.UnknownSignedness;
 
 /**
  * {@code values()} implementation for {@link ImmutableMap}.
@@ -70,7 +71,7 @@ public Spliterator<V> spliterator() {
   }
 
   @Override
-  public boolean contains(@CheckForNull Object object) {
+  public boolean contains(@CheckForNull @UnknownSignedness Object object) {
     return object != null && Iterators.contains(iterator(), object);
   }
 
diff --git a/guava/src/com/google/common/collect/ImmutableMultiset.java b/guava/src/com/google/common/collect/ImmutableMultiset.java
index 041184afbb84..001c0e72764d 100644
--- a/guava/src/com/google/common/collect/ImmutableMultiset.java
+++ b/guava/src/com/google/common/collect/ImmutableMultiset.java
@@ -348,7 +348,7 @@ public boolean equals(@CheckForNull @UnknownSignedness Object object) {
 
   @Pure
   @Override
-  public int hashCode() {
+  public int hashCode(@UnknownSignedness ImmutableMultiset<E> this) {
     return Sets.hashCodeImpl(entrySet());
   }
 
@@ -411,7 +411,7 @@ public boolean contains(@CheckForNull @UnknownSignedness Object o) {
 
     @Pure
     @Override
-    public int hashCode() {
+    public int hashCode(@UnknownSignedness EntrySet this) {
       return ImmutableMultiset.this.hashCode();
     }
 
diff --git a/guava/src/com/google/common/collect/ImmutableRangeMap.java b/guava/src/com/google/common/collect/ImmutableRangeMap.java
index f2d69a2932ad..b6cc0fa8e638 100644
--- a/guava/src/com/google/common/collect/ImmutableRangeMap.java
+++ b/guava/src/com/google/common/collect/ImmutableRangeMap.java
@@ -37,6 +37,7 @@
 import javax.annotation.CheckForNull;
 import org.checkerframework.checker.index.qual.NonNegative;
 import org.checkerframework.checker.nullness.qual.Nullable;
+import org.checkerframework.checker.signedness.qual.UnknownSignedness;
 
 /**
  * A {@link RangeMap} whose contents will never change, with many other important properties
@@ -387,7 +388,7 @@ public ImmutableRangeMap<K, V> subRangeMap(Range<K> subRange) {
   }
 
   @Override
-  public int hashCode() {
+  public int hashCode(@UnknownSignedness ImmutableRangeMap<K, V> this) {
     return asMapOfRanges().hashCode();
   }
 
diff --git a/guava/src/com/google/common/collect/ImmutableRangeSet.java b/guava/src/com/google/common/collect/ImmutableRangeSet.java
index 073707a48573..5e87614609ba 100644
--- a/guava/src/com/google/common/collect/ImmutableRangeSet.java
+++ b/guava/src/com/google/common/collect/ImmutableRangeSet.java
@@ -39,6 +39,7 @@
 import java.util.stream.Collector;
 import javax.annotation.CheckForNull;
 import org.checkerframework.checker.index.qual.NonNegative;
+import org.checkerframework.checker.signedness.qual.UnknownSignedness;
 
 /**
  * A {@link RangeSet} whose contents will never change, with many other important properties
@@ -644,7 +645,7 @@ ImmutableSortedSet<C> tailSetImpl(C fromElement, boolean inclusive) {
     }
 
     @Override
-    public boolean contains(@CheckForNull Object o) {
+    public boolean contains(@CheckForNull @UnknownSignedness Object o) {
       if (o == null) {
         return false;
       }
diff --git a/guava/src/com/google/common/collect/ImmutableSet.java b/guava/src/com/google/common/collect/ImmutableSet.java
index 359c92a34acb..ad804eea3b61 100644
--- a/guava/src/com/google/common/collect/ImmutableSet.java
+++ b/guava/src/com/google/common/collect/ImmutableSet.java
@@ -334,7 +334,7 @@ && hashCode() != object.hashCode()) {
 
   @Pure
   @Override
-  public int hashCode() {
+  public int hashCode(@UnknownSignedness ImmutableSet<E> this) {
     return Sets.hashCodeImpl(this);
   }
 
diff --git a/guava/src/com/google/common/collect/ImmutableSortedAsList.java b/guava/src/com/google/common/collect/ImmutableSortedAsList.java
index ba11b193932f..19d6908c5dfb 100644
--- a/guava/src/com/google/common/collect/ImmutableSortedAsList.java
+++ b/guava/src/com/google/common/collect/ImmutableSortedAsList.java
@@ -19,6 +19,7 @@
 import java.util.Comparator;
 import java.util.Spliterator;
 import javax.annotation.CheckForNull;
+import org.checkerframework.checker.signedness.qual.UnknownSignedness;
 
 /**
  * List returned by {@code ImmutableSortedSet.asList()} when the set isn't empty.
@@ -50,7 +51,7 @@ public Comparator<? super E> comparator() {
   @GwtIncompatible // ImmutableSortedSet.indexOf
   // TODO(cpovirk): consider manual binary search under GWT to preserve O(log N) lookup
   @Override
-  public int indexOf(@CheckForNull Object target) {
+  public int indexOf(@CheckForNull @UnknownSignedness Object target) {
     int index = delegateCollection().indexOf(target);
 
     // TODO(kevinb): reconsider if it's really worth making feeble attempts at
@@ -63,12 +64,12 @@ public int indexOf(@CheckForNull Object target) {
 
   @GwtIncompatible // ImmutableSortedSet.indexOf
   @Override
-  public int lastIndexOf(@CheckForNull Object target) {
+  public int lastIndexOf(@CheckForNull @UnknownSignedness Object target) {
     return indexOf(target);
   }
 
   @Override
-  public boolean contains(@CheckForNull Object target) {
+  public boolean contains(@CheckForNull @UnknownSignedness Object target) {
     // Necessary for ISS's with comparators inconsistent with equals.
     return indexOf(target) >= 0;
   }
diff --git a/guava/src/com/google/common/collect/ImmutableSortedMap.java b/guava/src/com/google/common/collect/ImmutableSortedMap.java
index d008faa8ebb6..adc7e11deedd 100644
--- a/guava/src/com/google/common/collect/ImmutableSortedMap.java
+++ b/guava/src/com/google/common/collect/ImmutableSortedMap.java
@@ -804,7 +804,7 @@ public void forEach(BiConsumer<? super K, ? super V> action) {
 
   @Override
   @CheckForNull
-  public V get(@CheckForNull Object key) {
+  public V get(@CheckForNull @UnknownSignedness Object key) {
     int index = keySet.indexOf(key);
     return (index == -1) ? null : valueList.get(index);
   }
@@ -868,7 +868,7 @@ ImmutableMap<K, V> map() {
 
     @Pure
     @Override
-    public boolean contains(@Nullable Object arg0) { return super.contains(arg0); }
+    public boolean contains(@Nullable @UnknownSignedness Object arg0) { return super.contains(arg0); }
     }
     return isEmpty() ? ImmutableSet.<Entry<K, V>>of() : new EntrySet();
   }
diff --git a/guava/src/com/google/common/collect/Interners.java b/guava/src/com/google/common/collect/Interners.java
index 10ae2746332b..cb44bc1990a5 100644
--- a/guava/src/com/google/common/collect/Interners.java
+++ b/guava/src/com/google/common/collect/Interners.java
@@ -23,6 +23,7 @@
 import com.google.common.collect.MapMaker.Dummy;
 import com.google.common.collect.MapMakerInternalMap.InternalEntry;
 import javax.annotation.CheckForNull;
+import org.checkerframework.checker.signedness.qual.UnknownSignedness;
 
 /**
  * Contains static methods pertaining to instances of {@link Interner}.
@@ -175,7 +176,7 @@ public E apply(E input) {
     }
 
     @Override
-    public int hashCode() {
+    public int hashCode(@UnknownSignedness InternerFunction<E> this) {
       return interner.hashCode();
     }
 
diff --git a/guava/src/com/google/common/collect/JdkBackedImmutableBiMap.java b/guava/src/com/google/common/collect/JdkBackedImmutableBiMap.java
index 5a8b1d3c3b78..e2c2720910f6 100644
--- a/guava/src/com/google/common/collect/JdkBackedImmutableBiMap.java
+++ b/guava/src/com/google/common/collect/JdkBackedImmutableBiMap.java
@@ -26,6 +26,7 @@
 import javax.annotation.CheckForNull;
 import org.checkerframework.checker.index.qual.NonNegative;
 import org.checkerframework.checker.nullness.qual.Nullable;
+import org.checkerframework.checker.signedness.qual.UnknownSignedness;
 
 /**
  * Implementation of ImmutableBiMap backed by a pair of JDK HashMaps, which have smartness
@@ -107,7 +108,7 @@ boolean isPartialView() {
 
   @Override
   @CheckForNull
-  public V get(@CheckForNull Object key) {
+  public V get(@CheckForNull @UnknownSignedness Object key) {
     return forwardDelegate.get(key);
   }
 
diff --git a/guava/src/com/google/common/collect/JdkBackedImmutableMap.java b/guava/src/com/google/common/collect/JdkBackedImmutableMap.java
index 8f1d78819e92..ac8cd7d64c6b 100644
--- a/guava/src/com/google/common/collect/JdkBackedImmutableMap.java
+++ b/guava/src/com/google/common/collect/JdkBackedImmutableMap.java
@@ -27,6 +27,7 @@
 import javax.annotation.CheckForNull;
 import org.checkerframework.checker.index.qual.NonNegative;
 import org.checkerframework.checker.nullness.qual.Nullable;
+import org.checkerframework.checker.signedness.qual.UnknownSignedness;
 
 /**
  * Implementation of ImmutableMap backed by a JDK HashMap, which has smartness protecting against
@@ -102,7 +103,7 @@ static <K, V> ImmutableMap<K, V> create(
 
   @Override
   @CheckForNull
-  public V get(@CheckForNull Object key) {
+  public V get(@CheckForNull @UnknownSignedness Object key) {
     return delegateMap.get(key);
   }
 
diff --git a/guava/src/com/google/common/collect/JdkBackedImmutableSet.java b/guava/src/com/google/common/collect/JdkBackedImmutableSet.java
index 6423792fab69..80a99ed7cc29 100644
--- a/guava/src/com/google/common/collect/JdkBackedImmutableSet.java
+++ b/guava/src/com/google/common/collect/JdkBackedImmutableSet.java
@@ -18,6 +18,7 @@
 import java.util.Set;
 import javax.annotation.CheckForNull;
 import org.checkerframework.checker.index.qual.NonNegative;
+import org.checkerframework.checker.signedness.qual.UnknownSignedness;
 
 /**
  * ImmutableSet implementation backed by a JDK HashSet, used to defend against apparent hash
@@ -43,7 +44,7 @@ E get(int index) {
   }
 
   @Override
-  public boolean contains(@CheckForNull Object object) {
+  public boolean contains(@CheckForNull @UnknownSignedness Object object) {
     return delegate.contains(object);
   }
 
diff --git a/guava/src/com/google/common/collect/LexicographicalOrdering.java b/guava/src/com/google/common/collect/LexicographicalOrdering.java
index 91fc7bf7241c..f0c78d7e272f 100644
--- a/guava/src/com/google/common/collect/LexicographicalOrdering.java
+++ b/guava/src/com/google/common/collect/LexicographicalOrdering.java
@@ -22,6 +22,7 @@
 import java.util.Iterator;
 import javax.annotation.CheckForNull;
 import org.checkerframework.checker.nullness.qual.Nullable;
+import org.checkerframework.checker.signedness.qual.UnknownSignedness;
 
 /** An ordering which sorts iterables by comparing corresponding elements pairwise. */
 @GwtCompatible(serializable = true)
@@ -66,7 +67,7 @@ public boolean equals(@CheckForNull Object object) {
   }
 
   @Override
-  public int hashCode() {
+  public int hashCode(@UnknownSignedness LexicographicalOrdering<T> this) {
     return elementOrder.hashCode() ^ 2075626741; // meaningless
   }
 
diff --git a/guava/src/com/google/common/collect/LinkedHashMultimap.java b/guava/src/com/google/common/collect/LinkedHashMultimap.java
index 61c029a88b61..66eafbeaea0a 100644
--- a/guava/src/com/google/common/collect/LinkedHashMultimap.java
+++ b/guava/src/com/google/common/collect/LinkedHashMultimap.java
@@ -474,7 +474,7 @@ public void forEach(Consumer<? super V> action) {
     }
 
     @Override
-    public boolean contains(@CheckForNull Object o) {
+    public boolean contains(@CheckForNull @UnknownSignedness Object o) {
       int smearedHash = Hashing.smearedHash(o);
       for (ValueEntry<K, V> entry = hashTable[smearedHash & mask()];
           entry != null;
diff --git a/guava/src/com/google/common/collect/LinkedListMultimap.java b/guava/src/com/google/common/collect/LinkedListMultimap.java
index 7499a24ea2b8..680b9e61d08c 100644
--- a/guava/src/com/google/common/collect/LinkedListMultimap.java
+++ b/guava/src/com/google/common/collect/LinkedListMultimap.java
@@ -754,7 +754,7 @@ public Iterator<K> iterator() {
 
       @Pure
       @Override
-      public boolean contains(@CheckForNull Object key) { // for performance
+      public boolean contains(@CheckForNull @UnknownSignedness Object key) { // for performance
         return containsKey(key);
       }
 
diff --git a/guava/src/com/google/common/collect/MapDifference.java b/guava/src/com/google/common/collect/MapDifference.java
index 4ff4e9cc6f91..d6f2f0b4947b 100644
--- a/guava/src/com/google/common/collect/MapDifference.java
+++ b/guava/src/com/google/common/collect/MapDifference.java
@@ -21,6 +21,7 @@
 import java.util.Map;
 import javax.annotation.CheckForNull;
 import org.checkerframework.checker.nullness.qual.Nullable;
+import org.checkerframework.checker.signedness.qual.UnknownSignedness;
 import org.checkerframework.dataflow.qual.Pure;
 import org.checkerframework.framework.qual.AnnotatedFor;
 
@@ -85,7 +86,7 @@ public interface MapDifference<K extends @Nullable Object, V extends @Nullable O
    */
   @Pure
   @Override
-  int hashCode();
+  int hashCode(@UnknownSignedness MapDifference<K, V> this);
 
   /**
    * A difference between the mappings from two maps with the same key. The {@link #leftValue} and
@@ -116,6 +117,6 @@ interface ValueDifference<V extends @Nullable Object> {
      */
     @Pure
     @Override
-    int hashCode();
+    int hashCode(@UnknownSignedness ValueDifference<V> this);
   }
 }
diff --git a/guava/src/com/google/common/collect/MapMakerInternalMap.java b/guava/src/com/google/common/collect/MapMakerInternalMap.java
index 68a1ef15c1b7..b4b1c8bc7a61 100644
--- a/guava/src/com/google/common/collect/MapMakerInternalMap.java
+++ b/guava/src/com/google/common/collect/MapMakerInternalMap.java
@@ -2664,7 +2664,7 @@ public boolean equals(@Nullable Object object) {
     }
 
     @Override
-    public int hashCode() {
+    public int hashCode(@UnknownSignedness WriteThroughEntry this) {
       // Cannot use key and value equivalence
       return key.hashCode() ^ value.hashCode();
     }
diff --git a/guava/src/com/google/common/collect/Maps.java b/guava/src/com/google/common/collect/Maps.java
index 93c138921ca7..84859e95644e 100644
--- a/guava/src/com/google/common/collect/Maps.java
+++ b/guava/src/com/google/common/collect/Maps.java
@@ -706,7 +706,7 @@ && entriesInCommon().equals(other.entriesInCommon())
 
     @Pure
     @Override
-    public int hashCode() {
+    public int hashCode(@UnknownSignedness MapDifferenceImpl<K, V> this) {
       return Objects.hashCode(
           entriesOnlyOnLeft(), entriesOnlyOnRight(), entriesInCommon(), entriesDiffering());
     }
@@ -772,7 +772,7 @@ public boolean equals(@CheckForNull Object object) {
 
     @Pure
     @Override
-    public int hashCode() {
+    public int hashCode(@UnknownSignedness ValueDifferenceImpl<V> this) {
       return Objects.hashCode(left, right);
     }
 
@@ -1562,7 +1562,7 @@ public Iterator<Entry<K, V>> iterator() {
     @CFComment({"signedness: is not applicable te `Entry` objects, which are the elements of the array",
             "nullness: the receiver is a collection of non-null `Entry` objects"})
     @Override
-    public Object[] toArray() {
+    public @PolyNull @PolySigned Object[] toArray() {
       /*
        * standardToArray returns `@Nullable Object[]` rather than `Object[]` but only because it can
        * be used with collections that may contain null. This collection never contains nulls, so we
@@ -1575,7 +1575,7 @@ public Object[] toArray() {
 
     @Override
     @SuppressWarnings("nullness") // b/192354773 in our checker affects toArray declarations
-    public <T extends @Nullable @UnknownSignedness Object> T[] toArray(T[] array) {
+    public <T extends @Nullable @UnknownSignedness Object> T[] toArray(@PolyNull T[] array) {
       return standardToArray(array);
     }
 
@@ -1605,7 +1605,7 @@ public boolean equals(@CheckForNull @UnknownSignedness Object object) {
 
     @Pure
     @Override
-    public int hashCode() {
+    public int hashCode(@UnknownSignedness UnmodifiableEntrySet<K, V> this) {
       return Sets.hashCodeImpl(this);
     }
   }
@@ -1658,7 +1658,7 @@ public boolean equals(@CheckForNull Object object) {
     }
 
     @Override
-    public int hashCode() {
+    public int hashCode(@UnknownSignedness BiMapConverter<A, B> this) {
       return bimap.hashCode();
     }
 
diff --git a/guava/src/com/google/common/collect/Multimap.java b/guava/src/com/google/common/collect/Multimap.java
index ca898c64d70d..07d9364a1dc2 100644
--- a/guava/src/com/google/common/collect/Multimap.java
+++ b/guava/src/com/google/common/collect/Multimap.java
@@ -397,5 +397,5 @@ default void forEach(BiConsumer<? super K, ? super V> action) {
    */
   @Pure
   @Override
-  int hashCode();
+  int hashCode(@UnknownSignedness Multimap<K, V> this);
 }
diff --git a/guava/src/com/google/common/collect/Multimaps.java b/guava/src/com/google/common/collect/Multimaps.java
index 6bb6bdb7e357..9a7fec20152f 100644
--- a/guava/src/com/google/common/collect/Multimaps.java
+++ b/guava/src/com/google/common/collect/Multimaps.java
@@ -1282,7 +1282,7 @@ Map<K, Collection<V>> createAsMap() {
 
     @Pure
     @Override
-    public int hashCode() {
+    public int hashCode(@UnknownSignedness MapMultimap<K, V> this) {
       return map.hashCode();
     }
 
diff --git a/guava/src/com/google/common/collect/Multiset.java b/guava/src/com/google/common/collect/Multiset.java
index 5739414ff974..cfa3adf164a4 100644
--- a/guava/src/com/google/common/collect/Multiset.java
+++ b/guava/src/com/google/common/collect/Multiset.java
@@ -327,7 +327,7 @@ interface Entry<E extends @Nullable Object> {
      */
     @Pure
     @Override
-    int hashCode();
+    int hashCode(@UnknownSignedness Entry<E> this);
 
     /**
      * Returns the canonical string representation of this entry, defined as follows. If the count
@@ -378,7 +378,7 @@ default void forEachEntry(ObjIntConsumer<? super E> action) {
    */
   @Pure
   @Override
-  int hashCode();
+  int hashCode(@UnknownSignedness Multiset<E> this);
 
   /**
    * {@inheritDoc}
diff --git a/guava/src/com/google/common/collect/Multisets.java b/guava/src/com/google/common/collect/Multisets.java
index 3d656cb9d0dd..c6a46509dbe3 100644
--- a/guava/src/com/google/common/collect/Multisets.java
+++ b/guava/src/com/google/common/collect/Multisets.java
@@ -864,7 +864,7 @@ public boolean equals(@CheckForNull Object object) {
      */
     @Pure
     @Override
-    public int hashCode() {
+    public int hashCode(@UnknownSignedness AbstractEntry<E> this) {
       E e = getElement();
       return ((e == null) ? 0 : e.hashCode()) ^ getCount();
     }
diff --git a/guava/src/com/google/common/collect/NullsFirstOrdering.java b/guava/src/com/google/common/collect/NullsFirstOrdering.java
index cceac05c539c..52e968a8fd13 100644
--- a/guava/src/com/google/common/collect/NullsFirstOrdering.java
+++ b/guava/src/com/google/common/collect/NullsFirstOrdering.java
@@ -20,6 +20,7 @@
 import java.io.Serializable;
 import javax.annotation.CheckForNull;
 import org.checkerframework.checker.nullness.qual.Nullable;
+import org.checkerframework.checker.signedness.qual.UnknownSignedness;
 import org.checkerframework.dataflow.qual.Pure;
 import org.checkerframework.framework.qual.AnnotatedFor;
 
@@ -83,7 +84,7 @@ public boolean equals(@CheckForNull Object object) {
 
   @Pure
   @Override
-  public int hashCode() {
+  public int hashCode(@UnknownSignedness NullsFirstOrdering<T> this) {
     return ordering.hashCode() ^ 957692532; // meaningless
   }
 
diff --git a/guava/src/com/google/common/collect/NullsLastOrdering.java b/guava/src/com/google/common/collect/NullsLastOrdering.java
index f80b33a6fcbf..d2f3cce7220f 100644
--- a/guava/src/com/google/common/collect/NullsLastOrdering.java
+++ b/guava/src/com/google/common/collect/NullsLastOrdering.java
@@ -20,6 +20,7 @@
 import java.io.Serializable;
 import javax.annotation.CheckForNull;
 import org.checkerframework.checker.nullness.qual.Nullable;
+import org.checkerframework.checker.signedness.qual.UnknownSignedness;
 import org.checkerframework.dataflow.qual.Pure;
 import org.checkerframework.framework.qual.AnnotatedFor;
 
@@ -83,7 +84,7 @@ public boolean equals(@CheckForNull Object object) {
 
   @Pure
   @Override
-  public int hashCode() {
+  public int hashCode(@UnknownSignedness NullsLastOrdering<T> this) {
     return ordering.hashCode() ^ -921210296; // meaningless
   }
 
diff --git a/guava/src/com/google/common/collect/Range.java b/guava/src/com/google/common/collect/Range.java
index 2a5d464dc2a8..661ae742ab18 100644
--- a/guava/src/com/google/common/collect/Range.java
+++ b/guava/src/com/google/common/collect/Range.java
@@ -29,6 +29,7 @@
 import java.util.NoSuchElementException;
 import java.util.SortedSet;
 import javax.annotation.CheckForNull;
+import org.checkerframework.checker.signedness.qual.UnknownSignedness;
 
 /**
  * A range (or "interval") defines the <i>boundaries</i> around a contiguous span of values of some
@@ -684,7 +685,7 @@ public boolean equals(@CheckForNull Object object) {
 
   /** Returns a hash code for this range. */
   @Override
-  public int hashCode() {
+  public int hashCode(@UnknownSignedness Range<C> this) {
     return lowerBound.hashCode() * 31 + upperBound.hashCode();
   }
 
diff --git a/guava/src/com/google/common/collect/RangeMap.java b/guava/src/com/google/common/collect/RangeMap.java
index 99e7b97d5ee9..69d6edcb2fcb 100644
--- a/guava/src/com/google/common/collect/RangeMap.java
+++ b/guava/src/com/google/common/collect/RangeMap.java
@@ -26,6 +26,7 @@
 import java.util.function.BiFunction;
 import javax.annotation.CheckForNull;
 import org.checkerframework.checker.nullness.qual.Nullable;
+import org.checkerframework.checker.signedness.qual.UnknownSignedness;
 
 /**
  * A mapping from disjoint nonempty ranges to non-null values. Queries look up the value associated
@@ -189,7 +190,7 @@ void merge(
 
   /** Returns {@code asMapOfRanges().hashCode()}. */
   @Override
-  int hashCode();
+  int hashCode(@UnknownSignedness RangeMap<K, V> this);
 
   /** Returns a readable string representation of this range map. */
   @Override
diff --git a/guava/src/com/google/common/collect/RangeSet.java b/guava/src/com/google/common/collect/RangeSet.java
index 79fbab159fa5..e420003ea3ce 100644
--- a/guava/src/com/google/common/collect/RangeSet.java
+++ b/guava/src/com/google/common/collect/RangeSet.java
@@ -20,6 +20,7 @@
 import java.util.NoSuchElementException;
 import java.util.Set;
 import javax.annotation.CheckForNull;
+import org.checkerframework.checker.signedness.qual.UnknownSignedness;
 
 /**
  * A set comprising zero or more {@linkplain Range#isEmpty nonempty}, {@linkplain
@@ -268,7 +269,7 @@ default void removeAll(Iterable<Range<C>> ranges) {
 
   /** Returns {@code asRanges().hashCode()}. */
   @Override
-  int hashCode();
+  int hashCode(@UnknownSignedness RangeSet<C> this);
 
   /**
    * Returns a readable string representation of this range set. For example, if this {@code
diff --git a/guava/src/com/google/common/collect/RegularContiguousSet.java b/guava/src/com/google/common/collect/RegularContiguousSet.java
index a9db661d6ffa..afd0417697d7 100644
--- a/guava/src/com/google/common/collect/RegularContiguousSet.java
+++ b/guava/src/com/google/common/collect/RegularContiguousSet.java
@@ -26,6 +26,7 @@
 import java.util.Collection;
 import javax.annotation.CheckForNull;
 import org.checkerframework.checker.index.qual.NonNegative;
+import org.checkerframework.checker.signedness.qual.UnknownSignedness;
 
 /**
  * An implementation of {@link ContiguousSet} that contains one or more elements.
@@ -154,7 +155,7 @@ public C get(int i) {
   }
 
   @Override
-  public boolean contains(@CheckForNull Object object) {
+  public boolean contains(@CheckForNull @UnknownSignedness Object object) {
     if (object == null) {
       return false;
     }
@@ -203,7 +204,7 @@ public Range<C> range(BoundType lowerBoundType, BoundType upperBoundType) {
   }
 
   @Override
-  public boolean equals(@CheckForNull Object object) {
+  public boolean equals(@CheckForNull @UnknownSignedness Object object) {
     if (object == this) {
       return true;
     } else if (object instanceof RegularContiguousSet) {
@@ -217,7 +218,7 @@ public boolean equals(@CheckForNull Object object) {
 
   // copied to make sure not to use the GWT-emulated version
   @Override
-  public int hashCode() {
+  public int hashCode(@UnknownSignedness RegularContiguousSet<C> this) {
     return Sets.hashCodeImpl(this);
   }
 
diff --git a/guava/src/com/google/common/collect/RegularImmutableBiMap.java b/guava/src/com/google/common/collect/RegularImmutableBiMap.java
index d07e079d6e90..d9cf279d9b78 100644
--- a/guava/src/com/google/common/collect/RegularImmutableBiMap.java
+++ b/guava/src/com/google/common/collect/RegularImmutableBiMap.java
@@ -177,7 +177,7 @@ boolean isHashCodeFast() {
   }
 
   @Override
-  public int hashCode() {
+  public int hashCode(@UnknownSignedness RegularImmutableBiMap<K, V> this) {
     return hashCode;
   }
 
@@ -259,7 +259,7 @@ boolean isHashCodeFast() {
       }
 
       @Override
-      public int hashCode() {
+      public int hashCode(@UnknownSignedness InverseEntrySet this) {
         return hashCode;
       }
 
diff --git a/guava/src/com/google/common/collect/RegularImmutableList.java b/guava/src/com/google/common/collect/RegularImmutableList.java
index e35b40c42f3c..89b5b29705db 100644
--- a/guava/src/com/google/common/collect/RegularImmutableList.java
+++ b/guava/src/com/google/common/collect/RegularImmutableList.java
@@ -118,7 +118,7 @@ public Spliterator<E> spliterator() {
 
 @Pure
 @Override
-public int hashCode() { return super.hashCode(); }
+public int hashCode(@UnknownSignedness RegularImmutableList<E> this) { return super.hashCode(); }
 
 @Pure
 @Override
diff --git a/guava/src/com/google/common/collect/RegularImmutableMultiset.java b/guava/src/com/google/common/collect/RegularImmutableMultiset.java
index 1169e124de4b..7408f5ec9f7c 100644
--- a/guava/src/com/google/common/collect/RegularImmutableMultiset.java
+++ b/guava/src/com/google/common/collect/RegularImmutableMultiset.java
@@ -194,7 +194,7 @@ Entry<E> getEntry(int index) {
   }
 
   @Override
-  public int hashCode() {
+  public int hashCode(@UnknownSignedness RegularImmutableMultiset<E> this) {
     return hashCode;
   }
 }
diff --git a/guava/src/com/google/common/collect/RegularImmutableSet.java b/guava/src/com/google/common/collect/RegularImmutableSet.java
index 7b79268e4f5a..a3cd41631285 100644
--- a/guava/src/com/google/common/collect/RegularImmutableSet.java
+++ b/guava/src/com/google/common/collect/RegularImmutableSet.java
@@ -23,6 +23,7 @@
 import javax.annotation.CheckForNull;
 import org.checkerframework.checker.index.qual.NonNegative;
 import org.checkerframework.checker.nullness.qual.Nullable;
+import org.checkerframework.checker.signedness.qual.UnknownSignedness;
 import org.checkerframework.dataflow.qual.Pure;
 import org.checkerframework.framework.qual.AnnotatedFor;
 
@@ -56,7 +57,7 @@ final class RegularImmutableSet<E> extends ImmutableSet.CachingAsList<E> {
 
   @Pure
   @Override
-  public boolean contains(@CheckForNull Object target) {
+  public boolean contains(@CheckForNull @UnknownSignedness Object target) {
     @Nullable Object[] table = this.table;
     if (target == null || table.length == 0) {
       return false;
@@ -122,7 +123,7 @@ boolean isPartialView() {
 
   @Pure
   @Override
-  public int hashCode() {
+  public int hashCode(@UnknownSignedness RegularImmutableSet<E> this) {
     return hashCode;
   }
 
diff --git a/guava/src/com/google/common/collect/ReverseOrdering.java b/guava/src/com/google/common/collect/ReverseOrdering.java
index 0f1ab8456783..fe6d7bec74cf 100644
--- a/guava/src/com/google/common/collect/ReverseOrdering.java
+++ b/guava/src/com/google/common/collect/ReverseOrdering.java
@@ -23,6 +23,7 @@
 import java.util.Iterator;
 import javax.annotation.CheckForNull;
 import org.checkerframework.checker.nullness.qual.Nullable;
+import org.checkerframework.checker.signedness.qual.UnknownSignedness;
 import org.checkerframework.dataflow.qual.Pure;
 import org.checkerframework.framework.qual.AnnotatedFor;
 
@@ -96,7 +97,7 @@ public <E extends T> E max(Iterable<E> iterable) {
 
   @Pure
   @Override
-  public int hashCode() {
+  public int hashCode(@UnknownSignedness ReverseOrdering<T> this) {
     return -forwardOrder.hashCode();
   }
 
diff --git a/guava/src/com/google/common/collect/Sets.java b/guava/src/com/google/common/collect/Sets.java
index 9b771f387586..f4d6f0175934 100644
--- a/guava/src/com/google/common/collect/Sets.java
+++ b/guava/src/com/google/common/collect/Sets.java
@@ -1145,7 +1145,7 @@ public boolean equals(@CheckForNull @UnknownSignedness Object object) {
     }
 
     @Override
-    public int hashCode() {
+    public int hashCode(@UnknownSignedness FilteredSet<E> this) {
       return hashCodeImpl(this);
     }
   }
@@ -1474,7 +1474,7 @@ public boolean equals(@CheckForNull @UnknownSignedness Object object) {
     }
 
     @Override
-    public int hashCode() {
+    public int hashCode(@UnknownSignedness CartesianSet<E> this) {
       // Warning: this is broken if size() == 0, so it is critical that we
       // substitute an empty ImmutableSet to the user in place of this
 
@@ -1617,7 +1617,7 @@ public boolean equals(@CheckForNull @UnknownSignedness Object obj) {
     }
 
     @Override
-    public int hashCode() {
+    public int hashCode(@UnknownSignedness PowerSet<E> this) {
       /*
        * The sum of the sums of the hash codes in each subset is just the sum of
        * each input element's hash code times the number of sets that element
diff --git a/guava/src/com/google/common/collect/SingletonImmutableList.java b/guava/src/com/google/common/collect/SingletonImmutableList.java
index 3a840b5aad7e..cb99bb68de2c 100644
--- a/guava/src/com/google/common/collect/SingletonImmutableList.java
+++ b/guava/src/com/google/common/collect/SingletonImmutableList.java
@@ -24,6 +24,7 @@
 import java.util.Spliterator;
 import org.checkerframework.checker.index.qual.NonNegative;
 import org.checkerframework.checker.nullness.qual.Nullable;
+import org.checkerframework.checker.signedness.qual.UnknownSignedness;
 import org.checkerframework.dataflow.qual.Pure;
 import org.checkerframework.dataflow.qual.SideEffectFree;
 import org.checkerframework.framework.qual.AnnotatedFor;
@@ -85,14 +86,14 @@ boolean isPartialView() {
   }
 
 @Pure
-public boolean contains(@Nullable Object arg0) { return super.contains(arg0); }
+public boolean contains(@Nullable @UnknownSignedness Object arg0) { return super.contains(arg0); }
 
 @Pure
-public boolean equals(@Nullable Object arg0) { return super.equals(arg0); }
+public boolean equals(@Nullable @UnknownSignedness Object arg0) { return super.equals(arg0); }
 
 @Pure
-public int indexOf(@Nullable Object arg0) { return super.indexOf(arg0); }
+public int indexOf(@Nullable @UnknownSignedness Object arg0) { return super.indexOf(arg0); }
 
 @Pure
-public int lastIndexOf(@Nullable Object arg0) { return super.lastIndexOf(arg0); }
+public int lastIndexOf(@Nullable @UnknownSignedness Object arg0) { return super.lastIndexOf(arg0); }
 }
diff --git a/guava/src/com/google/common/collect/SingletonImmutableSet.java b/guava/src/com/google/common/collect/SingletonImmutableSet.java
index 2de73aa7101e..50bdde7afcfd 100644
--- a/guava/src/com/google/common/collect/SingletonImmutableSet.java
+++ b/guava/src/com/google/common/collect/SingletonImmutableSet.java
@@ -22,6 +22,7 @@
 import javax.annotation.CheckForNull;
 import org.checkerframework.checker.index.qual.NonNegative;
 import org.checkerframework.checker.nullness.qual.Nullable;
+import org.checkerframework.checker.signedness.qual.UnknownSignedness;
 import org.checkerframework.dataflow.qual.Pure;
 import org.checkerframework.framework.qual.AnnotatedFor;
 import org.checkerframework.checker.nullness.qual.Nullable;
@@ -54,7 +55,7 @@ final class SingletonImmutableSet<E> extends ImmutableSet<E> {
 
   @Pure
   @Override
-  public boolean contains(@CheckForNull Object target) {
+  public boolean contains(@CheckForNull @UnknownSignedness Object target) {
     return element.equals(target);
   }
 
@@ -81,7 +82,7 @@ int copyIntoArray(@Nullable Object[] dst, int offset) {
 
   @Pure
   @Override
-  public final int hashCode() {
+  public int hashCode(@UnknownSignedness SingletonImmutableSet<E> this) {
     return element.hashCode();
   }
 
@@ -92,5 +93,5 @@ public String toString() {
   }
 
 @Pure
-public boolean equals(@Nullable Object arg0) { return super.equals(arg0); }
+public boolean equals(@Nullable @UnknownSignedness Object arg0) { return super.equals(arg0); }
 }
diff --git a/guava/src/com/google/common/collect/Synchronized.java b/guava/src/com/google/common/collect/Synchronized.java
index c3a8b4a2b141..2fbec1c64a9e 100644
--- a/guava/src/com/google/common/collect/Synchronized.java
+++ b/guava/src/com/google/common/collect/Synchronized.java
@@ -305,7 +305,7 @@ public boolean equals(@CheckForNull @UnknownSignedness Object o) {
 
     @Pure
     @Override
-    public int hashCode() {
+    public int hashCode(@UnknownSignedness SynchronizedSet<E> this) {
       synchronized (mutex) {
         return delegate().hashCode();
       }
@@ -496,7 +496,7 @@ public boolean equals(@CheckForNull @UnknownSignedness Object o) {
 
     @Pure
     @Override
-    public int hashCode() {
+    public int hashCode(@UnknownSignedness SynchronizedList<E> this) {
       synchronized (mutex) {
         return delegate().hashCode();
       }
@@ -606,7 +606,7 @@ public boolean equals(@CheckForNull @UnknownSignedness Object o) {
 
     @Pure
     @Override
-    public int hashCode() {
+    public int hashCode(@UnknownSignedness SynchronizedMultiset<E> this) {
       synchronized (mutex) {
         return delegate().hashCode();
       }
@@ -659,7 +659,7 @@ public boolean isEmpty() {
 
     @Pure
     @Override
-    public boolean containsKey(@CheckForNull Object key) {
+    public boolean containsKey(@CheckForNull @UnknownSignedness Object key) {
       synchronized (mutex) {
         return delegate().containsKey(key);
       }
@@ -810,7 +810,7 @@ public boolean equals(@CheckForNull Object o) {
 
     @Pure
     @Override
-    public int hashCode() {
+    public int hashCode(@UnknownSignedness SynchronizedMultimap<K, V> this) {
       synchronized (mutex) {
         return delegate().hashCode();
       }
@@ -1322,7 +1322,7 @@ public boolean equals(@CheckForNull Object o) {
 
     @Pure
     @Override
-    public int hashCode() {
+    public int hashCode(@UnknownSignedness SynchronizedMap<K, V> this) {
       synchronized (mutex) {
         return delegate().hashCode();
       }
@@ -1918,7 +1918,7 @@ public boolean equals(@CheckForNull Object obj) {
     }
 
     @Override
-    public int hashCode() {
+    public int hashCode(@UnknownSignedness SynchronizedEntry<K, V> this) {
       synchronized (mutex) {
         return delegate().hashCode();
       }
@@ -2320,7 +2320,7 @@ public Map<R, V> apply(Map<R, V> t) {
     }
 
     @Override
-    public int hashCode() {
+    public int hashCode(@UnknownSignedness SynchronizedTable<R, C, V> this) {
       synchronized (mutex) {
         return delegate().hashCode();
       }
diff --git a/guava/src/com/google/common/collect/Table.java b/guava/src/com/google/common/collect/Table.java
index 7821450634f7..5fe7202b0e1d 100644
--- a/guava/src/com/google/common/collect/Table.java
+++ b/guava/src/com/google/common/collect/Table.java
@@ -125,7 +125,7 @@ V get(
    * its cell view, as returned by {@link #cellSet}.
    */
   @Override
-  int hashCode();
+  int hashCode(@UnknownSignedness Table<R, C, V> this);
 
   // Mutators
 
@@ -285,6 +285,6 @@ interface Cell<
      * e.getColumnKey(), e.getValue())}.
      */
     @Override
-    int hashCode();
+    int hashCode(@UnknownSignedness Cell<R, C, V> this);
   }
 }
diff --git a/guava/src/com/google/common/collect/Tables.java b/guava/src/com/google/common/collect/Tables.java
index 151d4693213e..0c994ea521fc 100644
--- a/guava/src/com/google/common/collect/Tables.java
+++ b/guava/src/com/google/common/collect/Tables.java
@@ -188,7 +188,7 @@ public boolean equals(@CheckForNull Object obj) {
     }
 
     @Override
-    public int hashCode() {
+    public int hashCode(@UnknownSignedness AbstractCell<R, C, V> this) {
       return Objects.hashCode(getRowKey(), getColumnKey(), getValue());
     }
 
diff --git a/guava/src/com/google/common/collect/TreeBasedTable.java b/guava/src/com/google/common/collect/TreeBasedTable.java
index 96c2802e46bd..a99deaf0c229 100644
--- a/guava/src/com/google/common/collect/TreeBasedTable.java
+++ b/guava/src/com/google/common/collect/TreeBasedTable.java
@@ -33,6 +33,7 @@
 import java.util.TreeMap;
 import javax.annotation.CheckForNull;
 import org.checkerframework.checker.nullness.qual.KeyFor;
+import org.checkerframework.checker.signedness.qual.UnknownSignedness;
 
 /**
  * Implementation of {@code Table} whose row keys and column keys are ordered by their natural
@@ -286,7 +287,7 @@ void maintainEmptyInvariant() {
     }
 
     @Override
-    public boolean containsKey(@CheckForNull Object key) {
+    public boolean containsKey(@CheckForNull @UnknownSignedness Object key) {
       return rangeContains(key) && super.containsKey(key);
     }
 
diff --git a/guava/src/com/google/common/collect/TreeMultiset.java b/guava/src/com/google/common/collect/TreeMultiset.java
index 3e2561d7d564..2b3bd07940b6 100644
--- a/guava/src/com/google/common/collect/TreeMultiset.java
+++ b/guava/src/com/google/common/collect/TreeMultiset.java
@@ -1108,7 +1108,7 @@ private void readObject(ObjectInputStream stream) throws IOException, ClassNotFo
   private static final long serialVersionUID = 1;
 
 @Pure
-public boolean contains(@Nullable Object arg0) { return super.contains(arg0); }
+public boolean contains(@Nullable @UnknownSignedness Object arg0) { return super.contains(arg0); }
 
 public boolean containsAll(Collection<?> arg0) { return super.containsAll(arg0); }
 
diff --git a/guava/src/com/google/common/collect/TreeRangeMap.java b/guava/src/com/google/common/collect/TreeRangeMap.java
index f4c0ccf459af..bde057238026 100644
--- a/guava/src/com/google/common/collect/TreeRangeMap.java
+++ b/guava/src/com/google/common/collect/TreeRangeMap.java
@@ -633,7 +633,7 @@ public boolean equals(@CheckForNull Object o) {
     }
 
     @Override
-    public int hashCode() {
+    public int hashCode(@UnknownSignedness SubRangeMap this) {
       return asMapOfRanges().hashCode();
     }
 
@@ -815,7 +815,7 @@ public boolean equals(@CheckForNull Object o) {
   }
 
   @Override
-  public int hashCode() {
+  public int hashCode(@UnknownSignedness TreeRangeMap<K, V> this) {
     return asMapOfRanges().hashCode();
   }
 
diff --git a/guava/src/com/google/common/collect/TreeRangeSet.java b/guava/src/com/google/common/collect/TreeRangeSet.java
index 308992f804ba..d82f5423a914 100644
--- a/guava/src/com/google/common/collect/TreeRangeSet.java
+++ b/guava/src/com/google/common/collect/TreeRangeSet.java
@@ -32,6 +32,7 @@
 import java.util.TreeMap;
 import javax.annotation.CheckForNull;
 import org.checkerframework.checker.index.qual.NonNegative;
+import org.checkerframework.checker.signedness.qual.UnknownSignedness;
 
 /**
  * An implementation of {@link RangeSet} backed by a {@link TreeMap}.
@@ -109,12 +110,12 @@ protected Collection<Range<C>> delegate() {
     }
 
     @Override
-    public int hashCode() {
+    public int hashCode(@UnknownSignedness AsRanges this) {
       return Sets.hashCodeImpl(this);
     }
 
     @Override
-    public boolean equals(@CheckForNull Object o) {
+    public boolean equals(@CheckForNull @UnknownSignedness Object o) {
       return Sets.equalsImpl(this, o);
     }
   }
@@ -338,13 +339,13 @@ public Comparator<? super Cut<C>> comparator() {
     }
 
     @Override
-    public boolean containsKey(@CheckForNull Object key) {
+    public boolean containsKey(@CheckForNull @UnknownSignedness Object key) {
       return get(key) != null;
     }
 
     @Override
     @CheckForNull
-    public Range<C> get(@CheckForNull Object key) {
+    public Range<C> get(@CheckForNull @UnknownSignedness Object key) {
       if (key instanceof Cut) {
         try {
           @SuppressWarnings("unchecked") // we catch CCEs
@@ -634,7 +635,7 @@ protected Entry<Cut<C>, Range<C>> computeNext() {
 
     @Override
     @CheckForNull
-    public Range<C> get(@CheckForNull Object key) {
+    public Range<C> get(@CheckForNull @UnknownSignedness Object key) {
       if (key instanceof Cut) {
         try {
           @SuppressWarnings("unchecked")
@@ -652,7 +653,7 @@ public Range<C> get(@CheckForNull Object key) {
     }
 
     @Override
-    public boolean containsKey(@CheckForNull Object key) {
+    public boolean containsKey(@CheckForNull @UnknownSignedness Object key) {
       return get(key) != null;
     }
   }
@@ -746,13 +747,13 @@ public Comparator<? super Cut<C>> comparator() {
     }
 
     @Override
-    public boolean containsKey(@CheckForNull Object key) {
+    public boolean containsKey(@CheckForNull @UnknownSignedness Object key) {
       return get(key) != null;
     }
 
     @Override
     @CheckForNull
-    public Range<C> get(@CheckForNull Object key) {
+    public Range<C> get(@CheckForNull @UnknownSignedness Object key) {
       if (key instanceof Cut) {
         try {
           @SuppressWarnings("unchecked") // we catch CCE's
diff --git a/guava/src/com/google/common/eventbus/Subscriber.java b/guava/src/com/google/common/eventbus/Subscriber.java
index 71ee197c9b25..42f7e93032eb 100644
--- a/guava/src/com/google/common/eventbus/Subscriber.java
+++ b/guava/src/com/google/common/eventbus/Subscriber.java
@@ -22,6 +22,7 @@
 import java.lang.reflect.Method;
 import java.util.concurrent.Executor;
 import javax.annotation.CheckForNull;
+import org.checkerframework.checker.signedness.qual.UnknownSignedness;
 
 /**
  * A subscriber method on a specific object, plus the executor that should be used for dispatching
@@ -101,7 +102,7 @@ private SubscriberExceptionContext context(Object event) {
   }
 
   @Override
-  public final int hashCode() {
+  public final int hashCode(@UnknownSignedness Subscriber this) {
     return (31 + method.hashCode()) * 31 + System.identityHashCode(target);
   }
 
diff --git a/guava/src/com/google/common/eventbus/SubscriberRegistry.java b/guava/src/com/google/common/eventbus/SubscriberRegistry.java
index 46e982016c55..c9df205fa76a 100644
--- a/guava/src/com/google/common/eventbus/SubscriberRegistry.java
+++ b/guava/src/com/google/common/eventbus/SubscriberRegistry.java
@@ -47,6 +47,7 @@
 import java.util.concurrent.ConcurrentMap;
 import java.util.concurrent.CopyOnWriteArraySet;
 import javax.annotation.CheckForNull;
+import org.checkerframework.checker.signedness.qual.UnknownSignedness;
 
 /**
  * Registry of subscribers to a single event bus.
@@ -254,7 +255,7 @@ private static final class MethodIdentifier {
     }
 
     @Override
-    public int hashCode() {
+    public int hashCode(@UnknownSignedness MethodIdentifier this) {
       return Objects.hashCode(name, parameterTypes);
     }
 
diff --git a/guava/src/com/google/common/graph/AbstractGraph.java b/guava/src/com/google/common/graph/AbstractGraph.java
index 9402be5d9360..4deb3aab45e1 100644
--- a/guava/src/com/google/common/graph/AbstractGraph.java
+++ b/guava/src/com/google/common/graph/AbstractGraph.java
@@ -18,6 +18,7 @@
 
 import com.google.common.annotations.Beta;
 import javax.annotation.CheckForNull;
+import org.checkerframework.checker.signedness.qual.UnknownSignedness;
 
 /**
  * This class provides a skeletal implementation of {@link Graph}. It is recommended to extend this
@@ -47,7 +48,7 @@ && nodes().equals(other.nodes())
   }
 
   @Override
-  public final int hashCode() {
+  public final int hashCode(@UnknownSignedness AbstractGraph<N> this) {
     return edges().hashCode();
   }
 
diff --git a/guava/src/com/google/common/graph/AbstractNetwork.java b/guava/src/com/google/common/graph/AbstractNetwork.java
index ab002bfd0e19..0dc773b6fa4e 100644
--- a/guava/src/com/google/common/graph/AbstractNetwork.java
+++ b/guava/src/com/google/common/graph/AbstractNetwork.java
@@ -275,7 +275,7 @@ && nodes().equals(other.nodes())
   }
 
   @Override
-  public final int hashCode() {
+  public final int hashCode(@UnknownSignedness AbstractNetwork<N, E> this) {
     return edgeIncidentNodesMap(this).hashCode();
   }
 
diff --git a/guava/src/com/google/common/graph/AbstractValueGraph.java b/guava/src/com/google/common/graph/AbstractValueGraph.java
index 5b8e520c35e8..f4e00829c2fa 100644
--- a/guava/src/com/google/common/graph/AbstractValueGraph.java
+++ b/guava/src/com/google/common/graph/AbstractValueGraph.java
@@ -25,6 +25,7 @@
 import java.util.Optional;
 import java.util.Set;
 import javax.annotation.CheckForNull;
+import org.checkerframework.checker.signedness.qual.UnknownSignedness;
 
 /**
  * This class provides a skeletal implementation of {@link ValueGraph}. It is recommended to extend
@@ -134,7 +135,7 @@ && nodes().equals(other.nodes())
   }
 
   @Override
-  public final int hashCode() {
+  public final int hashCode(@UnknownSignedness AbstractValueGraph<N, V> this) {
     return edgeValueMap(this).hashCode();
   }
 
diff --git a/guava/src/com/google/common/graph/DirectedGraphConnections.java b/guava/src/com/google/common/graph/DirectedGraphConnections.java
index 8d72a786f859..e58a772970aa 100644
--- a/guava/src/com/google/common/graph/DirectedGraphConnections.java
+++ b/guava/src/com/google/common/graph/DirectedGraphConnections.java
@@ -95,7 +95,7 @@ public boolean equals(@CheckForNull Object that) {
       }
 
       @Override
-      public int hashCode() {
+      public int hashCode(@UnknownSignedness Pred<N> this) {
         // Adding the class hashCode to avoid a clash with Succ instances.
         return Pred.class.hashCode() + node.hashCode();
       }
@@ -116,7 +116,7 @@ public boolean equals(@CheckForNull Object that) {
       }
 
       @Override
-      public int hashCode() {
+      public int hashCode(@UnknownSignedness Succ<N> this) {
         // Adding the class hashCode to avoid a clash with Pred instances.
         return Succ.class.hashCode() + node.hashCode();
       }
@@ -465,7 +465,7 @@ public void removePredecessor(N node) {
   @SuppressWarnings("unchecked")
   @Override
   @CheckForNull
-  public V removeSuccessor(Object node) {
+  public V removeSuccessor(@UnknownSignedness Object node) {
     checkNotNull(node);
     Object previousValue = adjacentNodeValues.get(node);
     Object removedValue;
diff --git a/guava/src/com/google/common/graph/ElementOrder.java b/guava/src/com/google/common/graph/ElementOrder.java
index b5985a280b86..24a0c1de65a9 100644
--- a/guava/src/com/google/common/graph/ElementOrder.java
+++ b/guava/src/com/google/common/graph/ElementOrder.java
@@ -29,6 +29,7 @@
 import java.util.Comparator;
 import java.util.Map;
 import javax.annotation.CheckForNull;
+import org.checkerframework.checker.signedness.qual.UnknownSignedness;
 
 /**
  * Used to represent the order of elements in a data structure that supports different options for
@@ -174,7 +175,7 @@ public boolean equals(@CheckForNull Object obj) {
   }
 
   @Override
-  public int hashCode() {
+  public int hashCode(@UnknownSignedness ElementOrder<T> this) {
     return Objects.hashCode(type, comparator);
   }
 
diff --git a/guava/src/com/google/common/graph/EndpointPair.java b/guava/src/com/google/common/graph/EndpointPair.java
index fe2397c6b97b..2b939077bdec 100644
--- a/guava/src/com/google/common/graph/EndpointPair.java
+++ b/guava/src/com/google/common/graph/EndpointPair.java
@@ -25,6 +25,7 @@
 import com.google.common.collect.UnmodifiableIterator;
 import com.google.errorprone.annotations.Immutable;
 import javax.annotation.CheckForNull;
+import org.checkerframework.checker.signedness.qual.UnknownSignedness;
 
 /**
  * An immutable pair representing the two endpoints of an edge in a graph. The {@link EndpointPair}
@@ -142,7 +143,7 @@ public final UnmodifiableIterator<N> iterator() {
    * nodeU().hashCode() + nodeV().hashCode()}.
    */
   @Override
-  public abstract int hashCode();
+  public abstract int hashCode(@UnknownSignedness EndpointPair<N> this);
 
   private static final class Ordered<N> extends EndpointPair<N> {
     private Ordered(N source, N target) {
@@ -182,7 +183,7 @@ public boolean equals(@CheckForNull Object obj) {
     }
 
     @Override
-    public int hashCode() {
+    public int hashCode(@UnknownSignedness Ordered<N> this) {
       return Objects.hashCode(source(), target());
     }
 
@@ -242,7 +243,7 @@ public boolean equals(@CheckForNull Object obj) {
     }
 
     @Override
-    public int hashCode() {
+    public int hashCode(@UnknownSignedness Unordered<N> this) {
       return nodeU().hashCode() + nodeV().hashCode();
     }
 
diff --git a/guava/src/com/google/common/graph/Graph.java b/guava/src/com/google/common/graph/Graph.java
index 5dc0e71faf6d..291fbed8efe3 100644
--- a/guava/src/com/google/common/graph/Graph.java
+++ b/guava/src/com/google/common/graph/Graph.java
@@ -21,6 +21,7 @@
 import java.util.Collection;
 import java.util.Set;
 import javax.annotation.CheckForNull;
+import org.checkerframework.checker.signedness.qual.UnknownSignedness;
 
 /**
  * An interface for <a
@@ -299,5 +300,5 @@ public interface Graph<N> extends BaseGraph<N> {
    * <p>A reference implementation of this is provided by {@link AbstractGraph#hashCode()}.
    */
   @Override
-  int hashCode();
+  int hashCode(@UnknownSignedness Graph<N> this);
 }
diff --git a/guava/src/com/google/common/graph/Network.java b/guava/src/com/google/common/graph/Network.java
index c700d3378de6..ea3195acf6bd 100644
--- a/guava/src/com/google/common/graph/Network.java
+++ b/guava/src/com/google/common/graph/Network.java
@@ -21,6 +21,7 @@
 import java.util.Optional;
 import java.util.Set;
 import javax.annotation.CheckForNull;
+import org.checkerframework.checker.signedness.qual.UnknownSignedness;
 
 /**
  * An interface for <a
@@ -426,5 +427,5 @@ public interface Network<N, E> extends SuccessorsFunction<N>, PredecessorsFuncti
    * <p>A reference implementation of this is provided by {@link AbstractNetwork#hashCode()}.
    */
   @Override
-  int hashCode();
+  int hashCode(@UnknownSignedness Network<N, E> this);
 }
diff --git a/guava/src/com/google/common/graph/ValueGraph.java b/guava/src/com/google/common/graph/ValueGraph.java
index a13e87eb9833..230e248ed05d 100644
--- a/guava/src/com/google/common/graph/ValueGraph.java
+++ b/guava/src/com/google/common/graph/ValueGraph.java
@@ -21,6 +21,7 @@
 import java.util.Optional;
 import java.util.Set;
 import javax.annotation.CheckForNull;
+import org.checkerframework.checker.signedness.qual.UnknownSignedness;
 
 /**
  * An interface for <a
@@ -361,5 +362,5 @@ public interface ValueGraph<N, V> extends BaseGraph<N> {
    * <p>A reference implementation of this is provided by {@link AbstractValueGraph#hashCode()}.
    */
   @Override
-  int hashCode();
+  int hashCode(@UnknownSignedness ValueGraph<N, V> this);
 }
diff --git a/guava/src/com/google/common/hash/BloomFilter.java b/guava/src/com/google/common/hash/BloomFilter.java
index e7e6ba96f403..601e08300a29 100644
--- a/guava/src/com/google/common/hash/BloomFilter.java
+++ b/guava/src/com/google/common/hash/BloomFilter.java
@@ -40,6 +40,7 @@
 import org.checkerframework.checker.index.qual.NonNegative;
 import org.checkerframework.checker.index.qual.Positive;
 import org.checkerframework.checker.nullness.qual.Nullable;
+import org.checkerframework.checker.signedness.qual.UnknownSignedness;
 import org.checkerframework.common.value.qual.IntRange;
 
 /**
@@ -296,7 +297,7 @@ public boolean equals(@CheckForNull Object object) {
   }
 
   @Override
-  public int hashCode() {
+  public int hashCode(@UnknownSignedness BloomFilter<T> this) {
     return Objects.hashCode(numHashFunctions, funnel, strategy, bits);
   }
 
diff --git a/guava/src/com/google/common/hash/BloomFilterStrategies.java b/guava/src/com/google/common/hash/BloomFilterStrategies.java
index 662a41890904..e20b398082c5 100644
--- a/guava/src/com/google/common/hash/BloomFilterStrategies.java
+++ b/guava/src/com/google/common/hash/BloomFilterStrategies.java
@@ -24,6 +24,7 @@
 import java.util.concurrent.atomic.AtomicLongArray;
 import javax.annotation.CheckForNull;
 import org.checkerframework.checker.nullness.qual.Nullable;
+import org.checkerframework.checker.signedness.qual.UnknownSignedness;
 import org.checkerframework.common.value.qual.IntRange;
 import org.checkerframework.common.value.qual.MinLen;
 
@@ -314,7 +315,7 @@ public boolean equals(@CheckForNull Object o) {
     }
 
     @Override
-    public int hashCode() {
+    public int hashCode(@UnknownSignedness LockFreeBitArray this) {
       // TODO(lowasser): avoid allocation here
       return Arrays.hashCode(toPlainArray(data));
     }
diff --git a/guava/src/com/google/common/hash/Funnels.java b/guava/src/com/google/common/hash/Funnels.java
index db88736065a0..62b3525b1d90 100644
--- a/guava/src/com/google/common/hash/Funnels.java
+++ b/guava/src/com/google/common/hash/Funnels.java
@@ -26,6 +26,7 @@
 import org.checkerframework.checker.index.qual.NonNegative;
 import org.checkerframework.checker.nullness.qual.Nullable;
 import org.checkerframework.checker.signedness.qual.PolySigned;
+import org.checkerframework.checker.signedness.qual.UnknownSignedness;
 import org.checkerframework.common.value.qual.MinLen;
 
 /**
@@ -122,7 +123,7 @@ public boolean equals(@CheckForNull Object o) {
     }
 
     @Override
-    public int hashCode() {
+    public int hashCode(@UnknownSignedness StringCharsetFunnel this) {
       return StringCharsetFunnel.class.hashCode() ^ charset.hashCode();
     }
 
@@ -209,7 +210,7 @@ public boolean equals(@CheckForNull Object o) {
     }
 
     @Override
-    public int hashCode() {
+    public int hashCode(@UnknownSignedness SequentialFunnel<E> this) {
       return SequentialFunnel.class.hashCode() ^ elementFunnel.hashCode();
     }
   }
diff --git a/guava/src/com/google/common/hash/HashCode.java b/guava/src/com/google/common/hash/HashCode.java
index 1e9b85a23e3f..d8e6fd470529 100644
--- a/guava/src/com/google/common/hash/HashCode.java
+++ b/guava/src/com/google/common/hash/HashCode.java
@@ -29,6 +29,7 @@
 import org.checkerframework.checker.index.qual.NonNegative;
 import org.checkerframework.checker.index.qual.SameLen;
 import org.checkerframework.checker.nullness.qual.Nullable;
+import org.checkerframework.checker.signedness.qual.UnknownSignedness;
 import org.checkerframework.common.value.qual.ArrayLenRange;
 import org.checkerframework.common.value.qual.IntRange;
 import org.checkerframework.common.value.qual.MinLen;
@@ -403,7 +404,7 @@ public final boolean equals(@CheckForNull Object object) {
    * probably not what you want to use.
    */
   @Override
-  public final int hashCode() {
+  public final int hashCode(@UnknownSignedness HashCode this) {
     // If we have at least 4 bytes (32 bits), just take the first 4 bytes. Since this is
     // already a (presumably) high-quality hash code, any four bytes of it will do.
     if (bits() >= 32) {
diff --git a/guava/src/com/google/common/hash/Hasher.java b/guava/src/com/google/common/hash/Hasher.java
index 91674eb2b0d6..ca606ce17635 100644
--- a/guava/src/com/google/common/hash/Hasher.java
+++ b/guava/src/com/google/common/hash/Hasher.java
@@ -22,6 +22,7 @@
 import java.nio.ByteBuffer;
 import java.nio.charset.Charset;
 import org.checkerframework.checker.nullness.qual.Nullable;
+import org.checkerframework.checker.signedness.qual.UnknownSignedness;
 
 /**
  * A {@link PrimitiveSink} that can compute a hash code after reading the input. Each hasher should
@@ -141,5 +142,5 @@ public interface Hasher extends PrimitiveSink {
    */
   @Override
   @Deprecated
-  int hashCode();
+  int hashCode(@UnknownSignedness Hasher this);
 }
diff --git a/guava/src/com/google/common/hash/Hashing.java b/guava/src/com/google/common/hash/Hashing.java
index de6f309c5f41..5c0d6789c978 100644
--- a/guava/src/com/google/common/hash/Hashing.java
+++ b/guava/src/com/google/common/hash/Hashing.java
@@ -32,6 +32,7 @@
 import org.checkerframework.checker.index.qual.NonNegative;
 import org.checkerframework.checker.index.qual.Positive;
 import org.checkerframework.checker.nullness.qual.Nullable;
+import org.checkerframework.checker.signedness.qual.UnknownSignedness;
 import org.checkerframework.common.value.qual.IntRange;
 import org.checkerframework.common.value.qual.MinLen;
 
@@ -723,7 +724,7 @@ public boolean equals(@CheckForNull Object object) {
     }
 
     @Override
-    public int hashCode() {
+    public int hashCode(@UnknownSignedness ConcatenatedHashFunction this) {
       return Arrays.hashCode(functions);
     }
   }
diff --git a/guava/src/com/google/common/hash/Murmur3_128HashFunction.java b/guava/src/com/google/common/hash/Murmur3_128HashFunction.java
index 762cc90ccc05..724fec48334c 100644
--- a/guava/src/com/google/common/hash/Murmur3_128HashFunction.java
+++ b/guava/src/com/google/common/hash/Murmur3_128HashFunction.java
@@ -34,6 +34,7 @@
 import javax.annotation.CheckForNull;
 import org.checkerframework.checker.index.qual.NonNegative;
 import org.checkerframework.checker.nullness.qual.Nullable;
+import org.checkerframework.checker.signedness.qual.UnknownSignedness;
 
 /**
  * See MurmurHash3_x64_128 in <a href="http://smhasher.googlecode.com/svn/trunk/MurmurHash3.cpp">the
@@ -82,7 +83,7 @@ public boolean equals(@CheckForNull Object object) {
   }
 
   @Override
-  public int hashCode() {
+  public int hashCode(@UnknownSignedness Murmur3_128HashFunction this) {
     return getClass().hashCode() ^ seed;
   }
 
diff --git a/guava/src/com/google/common/hash/Murmur3_32HashFunction.java b/guava/src/com/google/common/hash/Murmur3_32HashFunction.java
index 308ec8dc7db3..3386ddc7d70a 100644
--- a/guava/src/com/google/common/hash/Murmur3_32HashFunction.java
+++ b/guava/src/com/google/common/hash/Murmur3_32HashFunction.java
@@ -43,6 +43,7 @@
 import org.checkerframework.checker.index.qual.LTLengthOf;
 import org.checkerframework.checker.index.qual.NonNegative;
 import org.checkerframework.checker.nullness.qual.Nullable;
+import org.checkerframework.checker.signedness.qual.UnknownSignedness;
 import org.checkerframework.common.value.qual.MinLen;
 
 /**
@@ -105,7 +106,7 @@ public boolean equals(@CheckForNull Object object) {
   }
 
   @Override
-  public int hashCode() {
+  public int hashCode(@UnknownSignedness Murmur3_32HashFunction this) {
     return getClass().hashCode() ^ seed;
   }
 
diff --git a/guava/src/com/google/common/hash/SipHashFunction.java b/guava/src/com/google/common/hash/SipHashFunction.java
index a854db188ff2..ab94b0cf0191 100644
--- a/guava/src/com/google/common/hash/SipHashFunction.java
+++ b/guava/src/com/google/common/hash/SipHashFunction.java
@@ -27,6 +27,7 @@
 import javax.annotation.CheckForNull;
 import org.checkerframework.checker.index.qual.NonNegative;
 import org.checkerframework.checker.nullness.qual.Nullable;
+import org.checkerframework.checker.signedness.qual.UnknownSignedness;
 
 /**
  * {@link HashFunction} implementation of SipHash-c-d.
@@ -93,7 +94,7 @@ public boolean equals(@CheckForNull Object object) {
   }
 
   @Override
-  public int hashCode() {
+  public int hashCode(@UnknownSignedness SipHashFunction this) {
     return (int) (getClass().hashCode() ^ c ^ d ^ k0 ^ k1);
   }
 
diff --git a/guava/src/com/google/common/io/BaseEncoding.java b/guava/src/com/google/common/io/BaseEncoding.java
index 3e7d5450c90b..01f58a29d32a 100644
--- a/guava/src/com/google/common/io/BaseEncoding.java
+++ b/guava/src/com/google/common/io/BaseEncoding.java
@@ -44,6 +44,7 @@
 import org.checkerframework.checker.index.qual.NonNegative;
 import org.checkerframework.checker.nullness.qual.Nullable;
 import org.checkerframework.checker.signedness.qual.PolySigned;
+import org.checkerframework.checker.signedness.qual.UnknownSignedness;
 import org.checkerframework.common.value.qual.ArrayLen;
 import org.checkerframework.common.value.qual.MinLen;
 
@@ -567,7 +568,7 @@ public boolean equals(@CheckForNull Object other) {
     }
 
     @Override
-    public int hashCode() {
+    public int hashCode(@UnknownSignedness Alphabet this) {
       return Arrays.hashCode(chars);
     }
   }
@@ -892,7 +893,7 @@ public boolean equals(@CheckForNull Object other) {
     }
 
     @Override
-    public int hashCode() {
+    public int hashCode(@UnknownSignedness StandardBaseEncoding this) {
       return alphabet.hashCode() ^ Objects.hashCode(paddingChar);
     }
   }
diff --git a/guava/src/com/google/common/math/PairedStats.java b/guava/src/com/google/common/math/PairedStats.java
index 31ab9b71966f..d6f16b0ca4bf 100644
--- a/guava/src/com/google/common/math/PairedStats.java
+++ b/guava/src/com/google/common/math/PairedStats.java
@@ -29,6 +29,7 @@
 import java.nio.ByteBuffer;
 import java.nio.ByteOrder;
 import javax.annotation.CheckForNull;
+import org.checkerframework.checker.signedness.qual.UnknownSignedness;
 
 /**
  * An immutable value object capturing some basic statistics about a collection of paired double
@@ -234,7 +235,7 @@ public boolean equals(@CheckForNull Object obj) {
    * including the floating point values. See the note on {@link #equals} for details.
    */
   @Override
-  public int hashCode() {
+  public int hashCode(@UnknownSignedness PairedStats this) {
     return Objects.hashCode(xStats, yStats, sumOfProductsOfDeltas);
   }
 
diff --git a/guava/src/com/google/common/math/Stats.java b/guava/src/com/google/common/math/Stats.java
index e7ecc97350ca..f1647481247d 100644
--- a/guava/src/com/google/common/math/Stats.java
+++ b/guava/src/com/google/common/math/Stats.java
@@ -38,6 +38,7 @@
 import java.util.stream.LongStream;
 import javax.annotation.CheckForNull;
 import org.checkerframework.checker.nullness.qual.Nullable;
+import org.checkerframework.checker.signedness.qual.UnknownSignedness;
 import org.checkerframework.common.value.qual.MinLen;
 
 /**
@@ -441,7 +442,7 @@ && doubleToLongBits(min) == doubleToLongBits(other.min)
    * including the floating point values. See the note on {@link #equals} for details.
    */
   @Override
-  public int hashCode() {
+  public int hashCode(@UnknownSignedness Stats this) {
     return Objects.hashCode(count, mean, sumOfSquaresOfDeltas, min, max);
   }
 
diff --git a/guava/src/com/google/common/net/HostAndPort.java b/guava/src/com/google/common/net/HostAndPort.java
index a27eb65ff3ba..225f14ea1ac6 100644
--- a/guava/src/com/google/common/net/HostAndPort.java
+++ b/guava/src/com/google/common/net/HostAndPort.java
@@ -26,6 +26,7 @@
 import com.google.errorprone.annotations.Immutable;
 import java.io.Serializable;
 import javax.annotation.CheckForNull;
+import org.checkerframework.checker.signedness.qual.UnknownSignedness;
 
 /**
  * An immutable representation of a host and port.
@@ -293,7 +294,7 @@ public boolean equals(@CheckForNull Object other) {
   }
 
   @Override
-  public int hashCode() {
+  public int hashCode(@UnknownSignedness HostAndPort this) {
     return Objects.hashCode(host, port);
   }
 
diff --git a/guava/src/com/google/common/net/HostSpecifier.java b/guava/src/com/google/common/net/HostSpecifier.java
index c57f3d97593c..a8bcfbc72b66 100644
--- a/guava/src/com/google/common/net/HostSpecifier.java
+++ b/guava/src/com/google/common/net/HostSpecifier.java
@@ -20,6 +20,7 @@
 import java.net.InetAddress;
 import java.text.ParseException;
 import javax.annotation.CheckForNull;
+import org.checkerframework.checker.signedness.qual.UnknownSignedness;
 
 /**
  * A syntactically valid host specifier, suitable for use in a URI. This may be either a numeric IP
@@ -152,7 +153,7 @@ public boolean equals(@CheckForNull Object other) {
   }
 
   @Override
-  public int hashCode() {
+  public int hashCode(@UnknownSignedness HostSpecifier this) {
     return canonicalForm.hashCode();
   }
 
diff --git a/guava/src/com/google/common/net/InternetDomainName.java b/guava/src/com/google/common/net/InternetDomainName.java
index d71a9d5c3c6c..fc68bbc62ec8 100644
--- a/guava/src/com/google/common/net/InternetDomainName.java
+++ b/guava/src/com/google/common/net/InternetDomainName.java
@@ -31,6 +31,7 @@
 import com.google.thirdparty.publicsuffix.PublicSuffixType;
 import java.util.List;
 import javax.annotation.CheckForNull;
+import org.checkerframework.checker.signedness.qual.UnknownSignedness;
 
 /**
  * An immutable well-formed internet domain name, such as {@code com} or {@code foo.co.uk}. Only
@@ -638,7 +639,7 @@ public boolean equals(@CheckForNull Object object) {
   }
 
   @Override
-  public int hashCode() {
+  public int hashCode(@UnknownSignedness InternetDomainName this) {
     return name.hashCode();
   }
 }
diff --git a/guava/src/com/google/common/net/MediaType.java b/guava/src/com/google/common/net/MediaType.java
index a713d0b17ae5..b66e7773c237 100644
--- a/guava/src/com/google/common/net/MediaType.java
+++ b/guava/src/com/google/common/net/MediaType.java
@@ -44,6 +44,7 @@
 import java.util.Map;
 import java.util.Map.Entry;
 import javax.annotation.CheckForNull;
+import org.checkerframework.checker.signedness.qual.UnknownSignedness;
 
 /**
  * Represents an <a href="http://en.wikipedia.org/wiki/Internet_media_type">Internet Media Type</a>
@@ -1144,7 +1145,7 @@ public boolean equals(@CheckForNull Object obj) {
   }
 
   @Override
-  public int hashCode() {
+  public int hashCode(@UnknownSignedness MediaType this) {
     // racy single-check idiom
     int h = hashCode;
     if (h == 0) {
diff --git a/guava/src/com/google/common/primitives/Booleans.java b/guava/src/com/google/common/primitives/Booleans.java
index 4b4dc5b3250a..3ea13c9103aa 100644
--- a/guava/src/com/google/common/primitives/Booleans.java
+++ b/guava/src/com/google/common/primitives/Booleans.java
@@ -514,7 +514,7 @@ public boolean equals(@CheckForNull @UnknownSignedness Object object) {
     }
 
     @Override
-    public int hashCode() {
+    public int hashCode(@UnknownSignedness BooleanArrayAsList this) {
       int result = 1;
       for (int i = start; i < end; i++) {
         result = 31 * result + Booleans.hashCode(array[i]);
diff --git a/guava/src/com/google/common/primitives/Bytes.java b/guava/src/com/google/common/primitives/Bytes.java
index 5c7bb7135059..4079eae3c3a1 100644
--- a/guava/src/com/google/common/primitives/Bytes.java
+++ b/guava/src/com/google/common/primitives/Bytes.java
@@ -379,7 +379,7 @@ public boolean equals(@CheckForNull @UnknownSignedness Object object) {
     }
 
     @Override
-    public int hashCode() {
+    public int hashCode(@UnknownSignedness ByteArrayAsList this) {
       int result = 1;
       for (int i = start; i < end; i++) {
         result = 31 * result + Bytes.hashCode(array[i]);
diff --git a/guava/src/com/google/common/primitives/Chars.java b/guava/src/com/google/common/primitives/Chars.java
index a53bb8a6caff..d7154f447bd2 100644
--- a/guava/src/com/google/common/primitives/Chars.java
+++ b/guava/src/com/google/common/primitives/Chars.java
@@ -649,7 +649,7 @@ public boolean equals(@CheckForNull @UnknownSignedness Object object) {
     }
 
     @Override
-    public int hashCode() {
+    public int hashCode(@UnknownSignedness CharArrayAsList this) {
       int result = 1;
       for (int i = start; i < end; i++) {
         result = 31 * result + Chars.hashCode(array[i]);
diff --git a/guava/src/com/google/common/primitives/Doubles.java b/guava/src/com/google/common/primitives/Doubles.java
index e0b020ae1dc5..a9af81b38025 100644
--- a/guava/src/com/google/common/primitives/Doubles.java
+++ b/guava/src/com/google/common/primitives/Doubles.java
@@ -663,7 +663,7 @@ public boolean equals(@CheckForNull @UnknownSignedness Object object) {
     }
 
     @Override
-    public int hashCode() {
+    public int hashCode(@UnknownSignedness DoubleArrayAsList this) {
       int result = 1;
       for (int i = start; i < end; i++) {
         result = 31 * result + Doubles.hashCode(array[i]);
diff --git a/guava/src/com/google/common/primitives/Floats.java b/guava/src/com/google/common/primitives/Floats.java
index c9c4a301f653..146fd575ae67 100644
--- a/guava/src/com/google/common/primitives/Floats.java
+++ b/guava/src/com/google/common/primitives/Floats.java
@@ -649,7 +649,7 @@ public boolean equals(@CheckForNull @UnknownSignedness Object object) {
     }
 
     @Override
-    public int hashCode() {
+    public int hashCode(@UnknownSignedness FloatArrayAsList this) {
       int result = 1;
       for (int i = start; i < end; i++) {
         result = 31 * result + Floats.hashCode(array[i]);
diff --git a/guava/src/com/google/common/primitives/ImmutableDoubleArray.java b/guava/src/com/google/common/primitives/ImmutableDoubleArray.java
index 9d138bbf0a2b..aeed1095e7e2 100644
--- a/guava/src/com/google/common/primitives/ImmutableDoubleArray.java
+++ b/guava/src/com/google/common/primitives/ImmutableDoubleArray.java
@@ -607,7 +607,7 @@ public boolean equals(@CheckForNull @UnknownSignedness Object object) {
 
     // Because we happen to use the same formula. If that changes, just don't override this.
     @Override
-    public int hashCode() {
+    public int hashCode(@UnknownSignedness AsList this) {
       return parent.hashCode();
     }
 
@@ -649,7 +649,7 @@ private static boolean areEqual(double a, double b) {
 
   /** Returns an unspecified hash code for the contents of this immutable array. */
   @Override
-  public int hashCode() {
+  public int hashCode(@UnknownSignedness ImmutableDoubleArray this) {
     int hash = 1;
     for (int i = start; i < end; i++) {
       hash *= 31;
diff --git a/guava/src/com/google/common/primitives/ImmutableIntArray.java b/guava/src/com/google/common/primitives/ImmutableIntArray.java
index 5d983e2bcd56..95fa420a958e 100644
--- a/guava/src/com/google/common/primitives/ImmutableIntArray.java
+++ b/guava/src/com/google/common/primitives/ImmutableIntArray.java
@@ -607,7 +607,7 @@ public boolean equals(@CheckForNull @UnknownSignedness Object object) {
 
     // Because we happen to use the same formula. If that changes, just don't override this.
     @Override
-    public int hashCode() {
+    public int hashCode(@UnknownSignedness AsList this) {
       return parent.hashCode();
     }
 
@@ -643,7 +643,7 @@ public boolean equals(@CheckForNull Object object) {
 
   /** Returns an unspecified hash code for the contents of this immutable array. */
   @Override
-  public int hashCode() {
+  public int hashCode(@UnknownSignedness ImmutableIntArray this) {
     int hash = 1;
     for (int i = start; i < end; i++) {
       hash *= 31;
diff --git a/guava/src/com/google/common/primitives/ImmutableLongArray.java b/guava/src/com/google/common/primitives/ImmutableLongArray.java
index 5612c751340b..941a4ca5dc62 100644
--- a/guava/src/com/google/common/primitives/ImmutableLongArray.java
+++ b/guava/src/com/google/common/primitives/ImmutableLongArray.java
@@ -609,7 +609,7 @@ public boolean equals(@CheckForNull @UnknownSignedness Object object) {
 
     // Because we happen to use the same formula. If that changes, just don't override this.
     @Override
-    public int hashCode() {
+    public int hashCode(@UnknownSignedness AsList this) {
       return parent.hashCode();
     }
 
@@ -645,7 +645,7 @@ public boolean equals(@CheckForNull Object object) {
 
   /** Returns an unspecified hash code for the contents of this immutable array. */
   @Override
-  public int hashCode() {
+  public int hashCode(@UnknownSignedness ImmutableLongArray this) {
     int hash = 1;
     for (int i = start; i < end; i++) {
       hash *= 31;
diff --git a/guava/src/com/google/common/primitives/Ints.java b/guava/src/com/google/common/primitives/Ints.java
index 906dcc3325f4..bd4a49b7c8a8 100644
--- a/guava/src/com/google/common/primitives/Ints.java
+++ b/guava/src/com/google/common/primitives/Ints.java
@@ -709,7 +709,7 @@ public boolean equals(@CheckForNull @UnknownSignedness Object object) {
     }
 
     @Override
-    public int hashCode() {
+    public int hashCode(@UnknownSignedness IntArrayAsList this) {
       int result = 1;
       for (int i = start; i < end; i++) {
         result = 31 * result + Ints.hashCode(array[i]);
diff --git a/guava/src/com/google/common/primitives/Longs.java b/guava/src/com/google/common/primitives/Longs.java
index 32082d8aba6b..2bfc3f7bb570 100644
--- a/guava/src/com/google/common/primitives/Longs.java
+++ b/guava/src/com/google/common/primitives/Longs.java
@@ -807,7 +807,7 @@ public boolean equals(@CheckForNull @UnknownSignedness Object object) {
     }
 
     @Override
-    public int hashCode() {
+    public int hashCode(@UnknownSignedness LongArrayAsList this) {
       int result = 1;
       for (int i = start; i < end; i++) {
         result = 31 * result + Longs.hashCode(array[i]);
diff --git a/guava/src/com/google/common/primitives/Shorts.java b/guava/src/com/google/common/primitives/Shorts.java
index 8c0b53195f47..9370fcebeec6 100644
--- a/guava/src/com/google/common/primitives/Shorts.java
+++ b/guava/src/com/google/common/primitives/Shorts.java
@@ -701,7 +701,7 @@ public boolean equals(@CheckForNull @UnknownSignedness Object object) {
     }
 
     @Override
-    public int hashCode() {
+    public int hashCode(@UnknownSignedness ShortArrayAsList this) {
       int result = 1;
       for (int i = start; i < end; i++) {
         result = 31 * result + Shorts.hashCode(array[i]);
diff --git a/guava/src/com/google/common/primitives/UnsignedInteger.java b/guava/src/com/google/common/primitives/UnsignedInteger.java
index 888031d4ae2f..96fc1cbaefbc 100644
--- a/guava/src/com/google/common/primitives/UnsignedInteger.java
+++ b/guava/src/com/google/common/primitives/UnsignedInteger.java
@@ -236,7 +236,7 @@ public int compareTo(UnsignedInteger other) {
   }
 
   @Override
-  public int hashCode() {
+  public int hashCode(@UnknownSignedness UnsignedInteger this) {
     return value;
   }
 
diff --git a/guava/src/com/google/common/primitives/UnsignedLong.java b/guava/src/com/google/common/primitives/UnsignedLong.java
index af72b5d55ca7..edcc662c564d 100644
--- a/guava/src/com/google/common/primitives/UnsignedLong.java
+++ b/guava/src/com/google/common/primitives/UnsignedLong.java
@@ -25,6 +25,7 @@
 import org.checkerframework.checker.index.qual.NonNegative;
 import org.checkerframework.checker.nullness.qual.Nullable;
 import org.checkerframework.checker.signedness.qual.Signed;
+import org.checkerframework.checker.signedness.qual.UnknownSignedness;
 import org.checkerframework.checker.signedness.qual.Unsigned;
 import org.checkerframework.common.value.qual.IntRange;
 import org.checkerframework.common.value.qual.PolyValue;
@@ -258,7 +259,7 @@ public int compareTo(UnsignedLong o) {
 
   @Override
   @SuppressWarnings("signedness:argument")
-  public int hashCode() {
+  public int hashCode(@UnknownSignedness UnsignedLong this) {
     return Longs.hashCode(value);
   }
 
diff --git a/guava/src/com/google/common/reflect/AbstractInvocationHandler.java b/guava/src/com/google/common/reflect/AbstractInvocationHandler.java
index ff921959db39..c79aa90970ff 100644
--- a/guava/src/com/google/common/reflect/AbstractInvocationHandler.java
+++ b/guava/src/com/google/common/reflect/AbstractInvocationHandler.java
@@ -20,6 +20,7 @@
 import java.util.Arrays;
 import javax.annotation.CheckForNull;
 import org.checkerframework.checker.nullness.qual.Nullable;
+import org.checkerframework.checker.signedness.qual.UnknownSignedness;
 
 /**
  * Abstract implementation of {@link InvocationHandler} that handles {@link Object#equals}, {@link
@@ -120,7 +121,7 @@ public boolean equals(@CheckForNull Object obj) {
    * delegate to this method. Subclasses can override this method to provide custom equality.
    */
   @Override
-  public int hashCode() {
+  public int hashCode(@UnknownSignedness AbstractInvocationHandler this) {
     return super.hashCode();
   }
 
diff --git a/guava/src/com/google/common/reflect/ClassPath.java b/guava/src/com/google/common/reflect/ClassPath.java
index 627532f8408e..20333d39fef9 100644
--- a/guava/src/com/google/common/reflect/ClassPath.java
+++ b/guava/src/com/google/common/reflect/ClassPath.java
@@ -50,6 +50,7 @@
 import java.util.jar.Manifest;
 import java.util.logging.Logger;
 import javax.annotation.CheckForNull;
+import org.checkerframework.checker.signedness.qual.UnknownSignedness;
 
 /**
  * Scans the source of a {@link ClassLoader} and finds all loadable classes and resources.
@@ -272,7 +273,7 @@ final File getFile() {
     }
 
     @Override
-    public int hashCode() {
+    public int hashCode(@UnknownSignedness ResourceInfo this) {
       return resourceName.hashCode();
     }
 
@@ -559,7 +560,7 @@ public boolean equals(@CheckForNull Object obj) {
     }
 
     @Override
-    public int hashCode() {
+    public int hashCode(@UnknownSignedness LocationInfo this) {
       return home.hashCode();
     }
 
diff --git a/guava/src/com/google/common/reflect/Invokable.java b/guava/src/com/google/common/reflect/Invokable.java
index e6d3b6c53f7f..f0df59fb2255 100644
--- a/guava/src/com/google/common/reflect/Invokable.java
+++ b/guava/src/com/google/common/reflect/Invokable.java
@@ -33,6 +33,7 @@
 import java.util.Arrays;
 import javax.annotation.CheckForNull;
 import org.checkerframework.checker.nullness.qual.Nullable;
+import org.checkerframework.checker.signedness.qual.UnknownSignedness;
 
 /**
  * Wrapper around either a {@link Method} or a {@link Constructor}. Convenience API is provided to
@@ -221,7 +222,7 @@ public boolean equals(@CheckForNull Object obj) {
   }
 
   @Override
-  public int hashCode() {
+  public int hashCode(@UnknownSignedness Invokable<T, R> this) {
     return member.hashCode();
   }
 
diff --git a/guava/src/com/google/common/reflect/Parameter.java b/guava/src/com/google/common/reflect/Parameter.java
index c3c46eca9d08..6b796f0d36fe 100644
--- a/guava/src/com/google/common/reflect/Parameter.java
+++ b/guava/src/com/google/common/reflect/Parameter.java
@@ -24,6 +24,7 @@
 import java.lang.reflect.AnnotatedType;
 import javax.annotation.CheckForNull;
 import org.checkerframework.checker.nullness.qual.Nullable;
+import org.checkerframework.checker.signedness.qual.UnknownSignedness;
 
 /**
  * Represents a method or constructor parameter.
@@ -140,7 +141,7 @@ public boolean equals(@CheckForNull Object obj) {
   }
 
   @Override
-  public int hashCode() {
+  public int hashCode(@UnknownSignedness Parameter this) {
     return position;
   }
 
diff --git a/guava/src/com/google/common/reflect/TypeParameter.java b/guava/src/com/google/common/reflect/TypeParameter.java
index 69cd8291a909..ec969a1b11fa 100644
--- a/guava/src/com/google/common/reflect/TypeParameter.java
+++ b/guava/src/com/google/common/reflect/TypeParameter.java
@@ -19,6 +19,7 @@
 import java.lang.reflect.Type;
 import java.lang.reflect.TypeVariable;
 import javax.annotation.CheckForNull;
+import org.checkerframework.checker.signedness.qual.UnknownSignedness;
 
 /**
  * Captures a free type variable that can be used in {@link TypeToken#where}. For example:
@@ -55,7 +56,7 @@ protected TypeParameter() {
   }
 
   @Override
-  public final int hashCode() {
+  public final int hashCode(@UnknownSignedness TypeParameter<T> this) {
     return typeVariable.hashCode();
   }
 
diff --git a/guava/src/com/google/common/reflect/TypeResolver.java b/guava/src/com/google/common/reflect/TypeResolver.java
index 32517eb8782f..063e7fd6f44c 100644
--- a/guava/src/com/google/common/reflect/TypeResolver.java
+++ b/guava/src/com/google/common/reflect/TypeResolver.java
@@ -35,6 +35,7 @@
 import java.util.Set;
 import java.util.concurrent.atomic.AtomicInteger;
 import javax.annotation.CheckForNull;
+import org.checkerframework.checker.signedness.qual.UnknownSignedness;
 
 /**
  * An object of this class encapsulates type mappings from type variables. Mappings are established
@@ -556,7 +557,7 @@ static final class TypeVariableKey {
     }
 
     @Override
-    public int hashCode() {
+    public int hashCode(@UnknownSignedness TypeVariableKey this) {
       return Objects.hashCode(var.getGenericDeclaration(), var.getName());
     }
 
diff --git a/guava/src/com/google/common/reflect/TypeToken.java b/guava/src/com/google/common/reflect/TypeToken.java
index fea1d53a2fab..0f93c7972798 100644
--- a/guava/src/com/google/common/reflect/TypeToken.java
+++ b/guava/src/com/google/common/reflect/TypeToken.java
@@ -48,6 +48,7 @@
 import java.util.Map;
 import java.util.Set;
 import javax.annotation.CheckForNull;
+import org.checkerframework.checker.signedness.qual.UnknownSignedness;
 
 /**
  * A {@link Type} with generics.
@@ -838,7 +839,7 @@ public boolean equals(@CheckForNull Object o) {
   }
 
   @Override
-  public int hashCode() {
+  public int hashCode(@UnknownSignedness TypeToken<T> this) {
     return runtimeType.hashCode();
   }
 
diff --git a/guava/src/com/google/common/reflect/Types.java b/guava/src/com/google/common/reflect/Types.java
index ef7dd5ad2c42..3f271994ef49 100644
--- a/guava/src/com/google/common/reflect/Types.java
+++ b/guava/src/com/google/common/reflect/Types.java
@@ -46,6 +46,7 @@
 import java.util.concurrent.atomic.AtomicReference;
 import javax.annotation.CheckForNull;
 import org.checkerframework.checker.nullness.qual.Nullable;
+import org.checkerframework.checker.signedness.qual.UnknownSignedness;
 import org.checkerframework.common.value.qual.MinLen;
 
 /**
@@ -239,7 +240,7 @@ public String toString() {
     }
 
     @Override
-    public int hashCode() {
+    public int hashCode(@UnknownSignedness GenericArrayTypeImpl this) {
       return componentType.hashCode();
     }
 
@@ -301,7 +302,7 @@ public String toString() {
     }
 
     @Override
-    public int hashCode() {
+    public int hashCode(@UnknownSignedness ParameterizedTypeImpl this) {
       return (ownerType == null ? 0 : ownerType.hashCode())
           ^ argumentsList.hashCode()
           ^ rawType.hashCode();
@@ -435,7 +436,7 @@ public String toString() {
     }
 
     @Override
-    public int hashCode() {
+    public int hashCode(@UnknownSignedness TypeVariableImpl<D> this) {
       return genericDeclaration.hashCode() ^ name.hashCode();
     }
 
@@ -500,7 +501,7 @@ public boolean equals(@CheckForNull Object obj) {
     }
 
     @Override
-    public int hashCode() {
+    public int hashCode(@UnknownSignedness WildcardTypeImpl this) {
       return lowerBounds.hashCode() ^ upperBounds.hashCode();
     }
 
diff --git a/pom.xml b/pom.xml
index 088202ecbc52..d2bd1be264c1 100644
--- a/pom.xml
+++ b/pom.xml
@@ -15,7 +15,7 @@
     <!-- Override this with -Dtest.include="**/SomeTest.java" on the CLI -->
     <test.include>%regex[.*.class]</test.include>
     <truth.version>1.1.2</truth.version>
-    <checker-framework.version>3.34.0</checker-framework.version>
+    <checker-framework.version>3.35.0</checker-framework.version>
     <animal.sniffer.version>1.20</animal.sniffer.version>
     <maven-javadoc-plugin.version>3.1.0</maven-javadoc-plugin.version>
     <!-- Empty for all JDKs but 9-12 -->

From 8e11911bcca51be2dac3fa292dac8b3c24c7ff85 Mon Sep 17 00:00:00 2001
From: Werner Dietl <wdietl@gmail.com>
Date: Mon, 9 Oct 2023 08:56:34 -0400
Subject: [PATCH 20/21] Use EISOP artifacts

---
 android/guava/pom.xml |  2 +-
 android/pom.xml       |  6 +++---
 guava-gwt/pom.xml     |  2 +-
 guava-testlib/pom.xml |  2 +-
 guava-tests/pom.xml   |  2 +-
 guava/pom.xml         | 14 +++++++-------
 pom.xml               |  8 ++++----
 typecheck.sh          |  5 ++---
 8 files changed, 20 insertions(+), 21 deletions(-)

diff --git a/android/guava/pom.xml b/android/guava/pom.xml
index 39611d4c9e3b..3ecf9bfbb95b 100644
--- a/android/guava/pom.xml
+++ b/android/guava/pom.xml
@@ -32,7 +32,7 @@
       <artifactId>jsr305</artifactId>
     </dependency>
     <dependency>
-      <groupId>org.checkerframework</groupId>
+      <groupId>io.github.eisop</groupId>
       <artifactId>checker-qual</artifactId>
     </dependency>
     <dependency>
diff --git a/android/pom.xml b/android/pom.xml
index 4e58c263d16b..b43ded2c27a4 100644
--- a/android/pom.xml
+++ b/android/pom.xml
@@ -267,17 +267,17 @@
         <version>3.0.2</version>
       </dependency>
       <dependency>
-        <groupId>org.checkerframework</groupId>
+        <groupId>io.github.eisop</groupId>
         <artifactId>checker-qual</artifactId>
         <version>${checker-framework.version}</version>
       </dependency>
       <dependency>
-        <groupId>org.checkerframework</groupId>
+        <groupId>io.github.eisop</groupId>
         <artifactId>checker-util</artifactId>
         <version>${checker-framework.version}</version>
       </dependency>
       <dependency>
-        <groupId>org.checkerframework</groupId>
+        <groupId>io.github.eisop</groupId>
         <artifactId>checker-qual</artifactId>
         <version>${checker-framework.version}</version>
         <classifier>sources</classifier>
diff --git a/guava-gwt/pom.xml b/guava-gwt/pom.xml
index f392a31e0192..73cb3b2e3f0d 100644
--- a/guava-gwt/pom.xml
+++ b/guava-gwt/pom.xml
@@ -104,7 +104,7 @@
       <scope>test</scope>
     </dependency>
     <dependency>
-      <groupId>org.checkerframework</groupId>
+      <groupId>io.github.eisop</groupId>
       <artifactId>checker-qual</artifactId>
     </dependency>
   </dependencies>
diff --git a/guava-testlib/pom.xml b/guava-testlib/pom.xml
index 19ce18a6049d..f667228227a7 100644
--- a/guava-testlib/pom.xml
+++ b/guava-testlib/pom.xml
@@ -19,7 +19,7 @@
       <artifactId>jsr305</artifactId>
     </dependency>
     <dependency>
-      <groupId>org.checkerframework</groupId>
+      <groupId>io.github.eisop</groupId>
       <artifactId>checker-qual</artifactId>
     </dependency>
     <dependency>
diff --git a/guava-tests/pom.xml b/guava-tests/pom.xml
index b7728d8b1b13..e0936a447c15 100644
--- a/guava-tests/pom.xml
+++ b/guava-tests/pom.xml
@@ -26,7 +26,7 @@
       <artifactId>jsr305</artifactId>
     </dependency>
     <dependency>
-      <groupId>org.checkerframework</groupId>
+      <groupId>io.github.eisop</groupId>
       <artifactId>checker-qual</artifactId>
     </dependency>
     <dependency>
diff --git a/guava/pom.xml b/guava/pom.xml
index c017817f67ae..124ffe1c9162 100644
--- a/guava/pom.xml
+++ b/guava/pom.xml
@@ -61,11 +61,11 @@
       <artifactId>jsr305</artifactId>
     </dependency>
     <dependency>
-      <groupId>org.checkerframework</groupId>
+      <groupId>io.github.eisop</groupId>
       <artifactId>checker-qual</artifactId>
     </dependency>
     <dependency>
-      <groupId>org.checkerframework</groupId>
+      <groupId>io.github.eisop</groupId>
       <artifactId>checker-util</artifactId>
     </dependency>
     <dependency>
@@ -83,15 +83,15 @@
        -P checkerframework-local -->
     <!-- Not needed; appears above.
     <dependency>
-      <groupId>org.checkerframework</groupId>
+      <groupId>io.github.eisop</groupId>
       <artifactId>checker-qual</artifactId>
       <version>2.5.5</version>
     </dependency>
     -->
     <dependency>
-      <groupId>org.checkerframework</groupId>
+      <groupId>io.github.eisop</groupId>
       <artifactId>checker</artifactId>
-      <version>3.35.0</version>
+      <version>3.34.0-eisop1</version>
     </dependency>
   </dependencies>
   <build>
@@ -381,14 +381,14 @@
       <id>checkerframework-local</id>
       <dependencies>
         <dependency>
-          <groupId>org.checkerframework</groupId>
+          <groupId>io.github.eisop</groupId>
           <artifactId>checker-qual</artifactId>
           <version>0.0.0</version>
           <scope>system</scope>
           <systemPath>${CHECKERFRAMEWORK}/checker/dist/checker-qual.jar</systemPath>
         </dependency>
         <dependency>
-          <groupId>org.checkerframework</groupId>
+          <groupId>io.github.eisop</groupId>
           <artifactId>checker</artifactId>
           <version>0.0.0</version>
           <scope>system</scope>
diff --git a/pom.xml b/pom.xml
index d2bd1be264c1..9a977e781694 100644
--- a/pom.xml
+++ b/pom.xml
@@ -15,7 +15,7 @@
     <!-- Override this with -Dtest.include="**/SomeTest.java" on the CLI -->
     <test.include>%regex[.*.class]</test.include>
     <truth.version>1.1.2</truth.version>
-    <checker-framework.version>3.35.0</checker-framework.version>
+    <checker-framework.version>3.34.0-eisop1</checker-framework.version>
     <animal.sniffer.version>1.20</animal.sniffer.version>
     <maven-javadoc-plugin.version>3.1.0</maven-javadoc-plugin.version>
     <!-- Empty for all JDKs but 9-12 -->
@@ -263,17 +263,17 @@
         <version>3.0.2</version>
       </dependency>
       <dependency>
-        <groupId>org.checkerframework</groupId>
+        <groupId>io.github.eisop</groupId>
         <artifactId>checker-qual</artifactId>
         <version>${checker-framework.version}</version>
       </dependency>
       <dependency>
-        <groupId>org.checkerframework</groupId>
+        <groupId>io.github.eisop</groupId>
         <artifactId>checker-util</artifactId>
         <version>${checker-framework.version}</version>
       </dependency>
       <dependency>
-        <groupId>org.checkerframework</groupId>
+        <groupId>io.github.eisop</groupId>
         <artifactId>checker-qual</artifactId>
         <version>${checker-framework.version}</version>
         <classifier>sources</classifier>
diff --git a/typecheck.sh b/typecheck.sh
index c41441aecd5b..bf3252eb7adb 100755
--- a/typecheck.sh
+++ b/typecheck.sh
@@ -13,11 +13,10 @@ set -e
 # If variable is set or directory exists, assume the Checker Framework is built.
 # Don't re-build because we might use wrong arguments (e.g., downloadjdk).
 if [ -z "${CHECKERFRAMEWORK}" ] && [ ! -d "../checker-framework/" ] ; then
-  (cd .. && git clone --depth 1 https://github.com/typetools/checker-framework.git)
+  (cd .. && git clone --depth 1 https://github.com/eisop/checker-framework.git)
   CHECKERFRAMEWORK=$(cd ../checker-framework/ >/dev/null 2>&1 && pwd -P)
   export CHECKERFRAMEWORK
-  # This also builds annotation-tools and jsr308-langtools
-  (cd "${CHECKERFRAMEWORK}" && checker/bin-devel/build.sh downloadjdk)
+  (cd "${CHECKERFRAMEWORK}" && checker/bin-devel/build.sh)
 fi
 
 # As of 7/27/2019, there are only annotations for:

From b701f07614692a0613cfc05c7cdee4c6f4ed99ac Mon Sep 17 00:00:00 2001
From: Werner Dietl <wdietl@gmail.com>
Date: Mon, 9 Oct 2023 10:26:05 -0400
Subject: [PATCH 21/21] Update version number

---
 android/pom.xml | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/android/pom.xml b/android/pom.xml
index b43ded2c27a4..429f85db9522 100644
--- a/android/pom.xml
+++ b/android/pom.xml
@@ -15,7 +15,7 @@
     <!-- Override this with -Dtest.include="**/SomeTest.java" on the CLI -->
     <test.include>%regex[.*.class]</test.include>
     <truth.version>1.1.2</truth.version>
-    <checker-framework.version>3.34.0</checker-framework.version>
+    <checker-framework.version>3.34.0-eisop1</checker-framework.version>
     <animal.sniffer.version>1.20</animal.sniffer.version>
     <maven-javadoc-plugin.version>3.1.0</maven-javadoc-plugin.version>
     <!-- Empty for all JDKs but 9-12 -->